INTRODUCTION
Purpose of thesis selection
The study of Automotive Braking, Suspension, and Steering Systems is crucial for engineering students specializing in Automotive Engineering This subject equips learners with essential knowledge about the structure and operating principles of various vehicle components It also enhances practical skills in disassembling and assembling detailed assemblies, enabling students to grasp the functionality of each system Furthermore, this foundational understanding aids in diagnosing vehicle faults effectively, ensuring a comprehensive grasp of automotive systems.
The diverse knowledge presented in books today can make it challenging for students to grasp complex systems like steering, power steering, and suspension To enhance understanding, it is essential for students to engage in both theoretical learning and practical application Utilizing available models in schools facilitates easier access to these subjects, allowing students to connect theory with practice effectively Recognizing this need, we have explored the theories behind steering systems, including electronic and hydraulic power steering, to create practical exercises that enhance learning By employing Bloom's Taxonomy, we aim to develop exercises that enable students to apply their theoretical knowledge directly to hands-on experiences with automotive chassis models.
Target of the research
The project enhances Automotive Engineering Technology students' understanding of electric and hydraulic power steering systems in a chassis workshop Students learn to identify and differentiate between system types, utilize diagnostic software, and understand key parameters of each system This knowledge equips them to effectively troubleshoot issues and self-assess their comprehension using Bloom's cognitive assessment taxonomy.
Objects of research
This lecture focuses on the Toyota Vios electric power steering system and the hydraulic power steering system, providing students with a comprehensive understanding of both theoretical concepts and practical models for easier comprehension.
The method of the research
The article explores the theory and operation of the Toyota Vios electric power steering and hydraulic power steering models It emphasizes the use of Techstream software for analyzing and interpreting various parameters Additionally, it provides exercises aligned with Bloom's taxonomy, focusing on levels such as memory, understanding, application, analysis, and evaluation, to enhance students' problem-solving skills related to the subject matter.
Knowledge of the research
- Structure, function and working principle of each system based on the available model
- How to use the software and read the fault diagnosis
- Search for data and documentation on vehicle systems
- Handle application exercises of each system, assess the level of understanding of students for each type.
Structure of thesis
- Main content section Consists of:
In the introduction, we explore the rationale behind selecting this topic, outline the objectives it aims to achieve, and discuss its limitations Additionally, we highlight the knowledge gained through this exploration and provide an overview of the thesis structure, setting the stage for a comprehensive analysis of the subject matter.
● Chapter 2: Literature review: This chapter presents the theory of steering systems, electronic power steering, hydraulic power steering
● Chapter 3: Building exercise base on model: In this chapter, show how to use the software, operate the model, build a lecture and give exercises to apply
● Chapter 4: Conclusion and recommendation: Give the conclusion of this thesis and suggestions for the topic (edit and hope for future development).
LITERATURE REVIEW
Overview about steering system
The steering system, originating in the 1850s, has undergone continuous improvements over the years to enhance the driving experience for users.
The steering system is a crucial component of a vehicle, responsible for controlling its motion trajectory based on the driver's input by rotating the guide wheels Its primary function is to adjust the direction of the car's movement, whether to change course or maintain a specific direction.
To steer a vehicle, the driver applies rotational force to the steering wheel, which is transmitted to the steering system via the steering shaft This shaft conveys torque to the steering mechanism, amplifying the steering wheel's torque before passing it to the steering rods Finally, these rods transfer the motion from the steering mechanism to the guide wheels, enabling precise vehicle direction adjustments.
2.1.1 The history about steering system
A mechanic by the name of Fitts installed the first power steering system on a car in
1876, but few people are aware of this The following generation was loaded onto a 5-ton capacity Colombian truck
In April 1900, Robert E Twyford from Pittsburgh, Pennsylvania, secured a patent for a mechanical power steering mechanism (patent number 646,477 U.S.), which he implemented in the first all-wheel drive vehicle.
In 1926, engineer Francis W Davis of Pierce-Arrow's truck division developed the first effective power steering system Afterward, he moved to General Motors, where he invented a hydraulic power system, but the company deemed it too costly for commercial production Davis later joined Bendix, a manufacturer of automotive parts.
During World War II, the military sought improved maneuverability for heavy vehicles, leading to the implementation of power steering in armored vehicles and tanks for both the US Army and Great Britain.
Chrysler introduced the first power steering system for a commercial passenger car in
In 1951, Chrysler introduced the Imperial, featuring a power steering system called "Hydraguide," which was based on several expired patents from Davis It wasn't until 1952 that General Motors launched a Cadillac equipped with a power steering system derived from innovations developed by Davis nearly two decades earlier.
NSK installed the first electric power steering system for forklifts in the world in 1986 For Japanese-sold micro automobiles, Koyo Seiko (now JTEKT) and NSK collaborated in
1988 to create the electric power steering system The Honda NSX received a completely direct control system without a clutch in 1990 [1]
Modern vehicles are increasingly equipped with advanced power steering systems to enhance driver experience, and ongoing improvements are expected to maximize their benefits in the future.
2.1.2 Requirements and classification of steering systems
The steering system must satisfy the following requirements:
The steering system should facilitate effortless and smooth turns, especially on narrow and curvy roads, allowing the vehicle to navigate tight spaces with ease.
For optimal steering performance, the steering wheel should be designed to provide a lighter feel at low speeds and a heavier sensation at high speeds, enhancing driver comfort and control.
A smooth return of the steering wheel is essential for driver comfort; after completing a turn, the driver should be able to easily guide the wheel back to its straight position without strain, allowing for a relaxed grip.
To minimize the transmission of bumps from the road surface, it is crucial to ensure proper turning kinematics This prevents wheel slip during turns and mitigates the impact of poor pavement, thereby maintaining steering control and reducing unwanted steering wheel rebound.
The mechanical steering system, first introduced in the 1950s with first-generation cars, has undergone continuous development and improvement Research focuses on enhancing straight motion stability while minimizing the force required on the steering wheel Key advancements ensure optimal rotational dynamics to prevent wheel slippage and maintain dynamic correspondence between the steering drive and suspension guide Additionally, the system effectively mitigates the impact of guide wheels on the steering wheel rim and maintains the motion relationship between the left and right wheels.
The mechanical steering system is comprised of two key components: the steering drive and the steering mechanism The steering mechanism acts as a torque converter, linking the turning angle of the guide wheels to the larger turning angle of the steering wheel Meanwhile, the steering drive transmits motion from the steering mechanism to the guide wheels, allowing them to rotate around the vertical column at varying speeds and angles, thereby preventing slippage during turns.
- The Hydraulic Power Steering - HPS
Hydraulic Power Steering enhances traditional mechanical steering systems by assisting drivers with vehicle control, ultimately improving driving comfort Additionally, it provides an important safety feature by maintaining control in the event of wheel failure, making it a significant advancement in steering technology.
Electric power steering
The electronically controlled power steering system enhances driving by providing auxiliary thrust to assist with steering, particularly during high-speed maneuvers This system reduces the driver's workload by partially taking over vehicle control, making it easier to navigate challenging situations By automatically adjusting to driving conditions, the electronic power steering improves safety for both the driver and other road users.
Figure 2.16 The component of Electric power steering system
Electric power steering systems are available in a variety of installations, depending on the power and power of the vehicle These things create driving stability, smoothness and comfort when driving
The EPSc steering system shares similarities with the traditional EPS steering system, which has been around for many years While the EPS system is primarily found in small cars with minimal power steering, the EPSc system features its power steering motor housed within the vehicle's interior compartment In our study, we focus on a specific model of the EPSc system.
+ Placed in the interior compartment helps to reduce the thermal impact from the engine
+ Compact system and low cost
The EPSp powertrain comprises the electric motor and ECU box situated in the engine compartment, making it susceptible to factors like temperature, installation location, and vibration, unlike the EPSc steering system While the power steering is responsible for rotating the steering shaft of the steering gear, it ultimately controls the rack, which presents limitations in force and torque during steering maneuvers.
+ No noise because the power assist is located outside the interior compartment
+ Need to make sure not to hit the foot space when impacted
+ Limited steering force and torque
The EPSdp steering system features an electric motor located in the rack, which is managed by a series of reduction gears By positioning the booster away from the steering shaft on the same rack, the sensor and actuator can be effectively separated This design allows for an optimal power arrangement, as the main gear ratio operates independently of the steering ratio.
+ Has 10-15% greater efficiency than C-EPS and P-EPS
+ The driving feel of this set-up is better
+ Limited installation space and complicated structure affect the repair
2.2.2 Structure of the electric power steering system
The torque sensor, positioned on the steering shaft, plays a crucial role in the system by detecting the rotation of the torsion bar It calculates the torque acting on the bar through changes in voltage and sends this voltage signal to the EPS ECU This allows the control box to assess the steering wheel's status, including direction and speed of movement, whether it's a sudden or gradual turn.
Figure 2.20 Location of the sensor on the system
• The structure of the torque sensor:
The system features an input shaft linked to the steering wheel (primary shaft) and an output shaft (secondary shaft) also connected to the steering wheel, with a torsion bar mounted between them The input shaft connects to the first generator rotor, which has slots aligned with the second generator, while the third generator's slots are oriented oppositely and connect to the output shaft Additionally, detection and correction coils are installed outside the emitter rotors.
On each coil will be connected to two wires to calculate the torque and then transmit the signal to the engine ECU [5]
Figure 2.21 Torque sensor when disassembled [5]
Figure 2.22 Structure of a torque sensor
• The principle of operation of the sensor:
The detection ring 1, in conjunction with the correction coil, identifies the neutral position of the torsion bar As the steering wheel turns left or right, torque is transmitted through the main steering shaft, causing the torsion bar to twist and altering the positions of detection rings 2 and 3 This twisting results in a phase difference between the two detection rings The emitter coil detects this deviation, producing voltage signals VT1 and VT2, which are approximately equal and proportional to the torque These signals are sent to the EPS ECU, which communicates with the vehicle's ECU via the CAN network protocol to calculate the necessary power steering torque based on vehicle speed and motor drive In the event of a torque sensor failure, the values of VT1 and VT2 will differ.
Figure 2.23 The signal of Torque sensor
The diagram illustrates the relationship between steering wheel position and output voltage, with a central reference point of 2.5V representing the wheel's neutral position When the steering wheel is turned to the right, the necessary voltage for steering torque exceeds 2.5V, while turning to the left results in a voltage below 2.5V.
It is composed of torsion bar, permanent magnet is mounted outside a torsion bar, in the middle there is a HALL sensor and outside is a positioning ring
The steering system operates by applying force to the steering wheel, which causes the torsion bar to rotate and generates a static magnetic field through a permanent magnet This magnetic field is detected by HALL sensors and a positioning ring, which monitor the direction of the steering wheel's rotation and the torque signal The collected data is then transmitted to the ECU for further processing.
The quantity of permanent magnets in EPS systems is influenced by the stiffness of the torsion bar For a torsion bar with a torsion angle of 2 Nm and a tolerance range of ± 10 Nm, a corresponding angle range of ± 5˚ is necessary.
Optical torque sensors measure the relative angular movement at the ends of a torsion bar when torque is applied to the shaft These sensors typically feature two concentric metal encoder discs attached to each end of the torsion bar, which rotate with the shaft Each disc contains a series of windows that allow light to pass through, facilitating the measurement process.
Figure 2.25 Schematic of the optical torque sensor [6]
The torque is determined by measuring the light pattern transmitted through two overlapping discs The "narrow spoke" disc's spokes align with the "wide spoke" disc's windows at zero torque When torque is applied, the torsion bar twists, causing the discs to shift and the spokes to move within the windows This motion is detected by the optical system, where light from an LED creates a shadow of the spoke edges on the receiver.
Figure 2.26 Disc overlap with different torques applied
− Torque sensor without torsion bar (Surface Acoustic Wave Torque Measurement) Includes metal and quartz electrode, RF transceiver, frequency signal processing IC
The measuring principle utilizes a Surface Acoustic Wave (SAW) resonator, which consists of thin metal electrodes coated with quartz on the drive shaft's surface RF transceivers are positioned at both ends of the shaft When torque is applied, it deforms the shaft and the quartz layer, leading to a shift in the resonant frequency This mechanism allows the SAW to function as a frequency-dependent strain gauge The measurement of the resonant frequency difference between transmitted and received signals, along with electronic processing and calibration, accurately indicates the torque transmitted by the shaft.
A DC motor comprises a stator, rotor, main shaft, and reducer, with the reducer consisting of a worm and worm gear The electric motor generates rotor torque, which is transmitted to the reducer and then to the main drive shaft To minimize noise and enhance longevity, the screw is supported by bearings, while the coupling prevents locking of the main drive shaft and reducer in case of engine failure, ensuring the steering system remains functional.
The actuator motor of the electric power steering is responsible for generating power steering depending on the power steering ECU signal and must meet the following requirements:
- The motor must be able to deliver torque and torque without turning the steering wheel
- The motor must have a mechanism to reverse rotation when a fault occurs
- The fluctuations of the motor and torque, the torque directly transferred through the steering wheel to the driver's hand must be handled and adjusted optimally
Figure 2.28 Cross section of DC power steering motor
1.Assistance motor 2.Reducing worm wheel 3.Worm screw
2.2.2.3 EPS ECU central control unit
The power steering ECU, located on the steering shaft, consists of motor control circuits that operate based on a preloaded program It receives voltage signals from both the steering torque sensor and the vehicle speed sensor Upon receiving these signals, the controller calculates the power steering lever value and determines the appropriate steering direction Consequently, the control unit generates an electric current to activate the electric motor in the steering box, enabling it to move the rack to the right or left with the necessary amount of power.
Requirements for power steering ECU: Ensure driving comfort (motor current control function) These functions include:
Hydraulic power steering system
The closed-loop hydraulic power steering system utilizes pressurized hydraulic fluids to adjust the front wheel angles based on the steering input This system comprises valves, a cylinder, a reservoir, a belt-driven hydraulic pump, and a driver control mechanism The rack, connected to a piston within the rack housing, operates through two hydraulic hose rods managed by hydraulic control valves When the driver turns the steering wheel, the hydraulic control valve directs power steering fluid to one side of the cylinder, moving the hydraulic piston and facilitating the desired wheel direction change.
Figure 2.32 The structure of Hydraulic power steering system
2.3.1 The component of the hydraulic power steering system
Power steering pumps are typically located in the engine compartment and are powered by the generator or A/C compressor They are connected to the engine via a belt-pulley system, utilizing an engine belt for operation.
Figure 2.33 The component of Power steering pump
When the engine starts, the drive belt activates the steering pump, causing its vane to rotate and generate a sealed pressure that draws oil from the reservoir The rotor features slots for impeller mounting, and due to the circular shape of the rotor's outer circumference and the oval shape of the cam ring's interior, a gap exists between the rotor and the cam ring.
The impeller creates oil chambers by separating a gap, held against the cam ring's inner surface by centrifugal force Oil pressure acts behind the impeller, forming a seal that prevents leakage during pump pressurization As the rotor rotates, the capacity of the oil chambers continuously fluctuates.
The oil chamber's capacity increases at the suction port, allowing oil from the tank to be drawn into it As oil is sucked into the chamber, the pressure at the discharge port decreases, facilitating the oil's movement through this outlet This suction and discharge cycle occurs with each rotation of the rotor shaft, and with two suction and two discharge ports, oil is efficiently drawn in and expelled twice per rotor rotation.
Figure 2.34 Internal structure of the power steeing pump
4) Pump ring 3,7) High-pressure oil line 6)Rotor 8) Pump vanes
The oil tank supplies power steering oil and can be mounted directly on the pump body or separately When not attached to the pump, it connects via two hoses: one for oil inlet to the power steering pump and another for the return oil pipe.
The tank cap typically includes a level gauge to monitor the oil level When the oil level in the reservoir falls below the standard threshold, the pump may draw in air, leading to operational errors.
Engine speed directly influences the oil flow to the power steering pump, thereby affecting the steering assistance provided to the driver At high speeds, increased oil flow enhances steering response, allowing the driver to maneuver with minimal effort Conversely, at low speeds, greater assistance is necessary to facilitate easier steering This variation in steering force with engine speed can negatively impact vehicle stability and the driver's steering experience.
To ensure a steady oil supply from the pump to the steering gear at any engine speed, the control valve plays a crucial role in regulating this flow.
Figure 2.36 Engine speed sensor type flow control valve
• The operation of flow control valve
+ Low speed: Pump speed from 650RPM to 1250RPM
Figure 2.37 Operating principle of control valve at low speed
At low speeds, the pump's outlet pressure at P1 influences the right side of the flow control valve, while pressure at P2 impacts the left side after traversing the hole As engine speed rises, the pressure differential between P1 and P2 becomes more pronounced.
As the pressure difference between P1 and P2 rises and surpasses the tension of the flow control valve spring, the valve shifts left, allowing oil to flow partially towards the pump's suction side This mechanism ensures a consistent supply of oil to the power steering system.
+ At medium speed: Pump speed from 1250RPM to 2500RPM
Figure 2.38 Operating principle of control valve at medium speed
When the pump speed exceeds 1250 RPM, the oil flow from the supply tank to pump P1 increases, resulting in higher discharge pressure on the control tube's left side, which compresses spring B This compression shifts the control to the right, narrowing the hole and reducing the oil flow, leading to a drop in pressure at P2 As the pressure at P1 rises, the pressure difference between P1 and P2 also increases, prompting the flow control valve to shift left and decrease the oil entering the steering box In summary, when the control tube shifts to the right, the oil flow through the holes diminishes Notably, at high speeds above 2500 RPM, this dynamic becomes even more pronounced.
Figure 2.39 Operating principle of control valve at high speed
When the pump speed exceeds 2500 RPM, the control pipe is pushed to the right by the oil pressure in space P1, resulting in a reduction of the hole size by half Consequently, the pressure P2 is solely influenced by the oil flow through the narrowed openings This action pushes the flow control valve to the left, allowing oil to bypass directly to the suction side and return to the pump, thereby keeping the oil supply to the steering gear box constant at a lower value.
+ Safety valve: Safety valve incorporated in control valve
Figure 2.40 Safety valve located in control valve
When the pressure P2 surpasses the designated limit—such as when the steering wheel is fully turned or the guide wheel is obstructed—the oil pressure rises above normal levels To alleviate this excess pressure, the safety valve activates, allowing oil to flow through the valve to the suction port, thereby reducing pressure within the system.
The hydraulic power steering system employs a rack screw mechanism, featuring a piston that separates the cylinder into two compartments—left and right The rack's movement is facilitated by the increased oil flow from the power steering pump acting on the piston Additionally, an oil seal is positioned above the piston to prevent leakage between the two chambers, while both cylinder heads are equipped with seals to avoid external oil leakage.
BUILDING EXERCISE BASE ON MODEL
The fundamentals of preparing exercises
The Ho Chi Minh University of Technology and Education is a renowned institution known for its excellent facilities and modern educational resources Its innovative teaching models enhance the learning experience, enabling lecturers to effectively deliver lessons while allowing students to easily grasp the knowledge presented in class.
In terms of the various models, the electric power steering system and hydraulic power steering system are included in the Practice of Automotive Braking, Suspension and Steering System
Students with high aspirations have developed theoretical lessons and exercises aligned with learning outcome standards and Bloom's taxonomy This approach enhances their understanding of system structures and working principles, allowing them to grasp lesson objectives and targets more effectively Additionally, it clarifies essential knowledge, making the teaching process more straightforward for lecturers.
What is Bloom?
Bloom’s Taxonomy, created by educational psychologist Benjamin Bloom in 1956, is a framework that classifies intellectual skills and behaviors essential for learning It encompasses six cognitive levels: knowledge, comprehension, application, analysis, synthesis, and evaluation, with complexity increasing from basic recall of information to higher-order evaluation skills.
Bloom’s Taxonomy, developed in 1948 by psychologist Benjamin Bloom and colleagues, was initially designed to classify educational goals for evaluating student performance Over the years, it has been revised and continues to be relevant in education The taxonomy focuses on three main learning domains: cognitive, affective, and psychomotor The cognitive domain emphasizes knowledge recall, intellectual abilities, and skill development; the affective domain addresses changes in attitudes, values, and interests; and the psychomotor domain relates to motor skills However, Bloom’s Taxonomy primarily applies to the cognitive domain, highlighting the importance of intellectual skill acquisition.
Bloom's Taxonomy originally comprised six developmental categories: knowledge, comprehension, application, analysis, synthesis, and evaluation The first level emphasizes knowledge acquisition, where students recall and memorize information The second tier involves classifying, describing, and solving problems based on what they have learned In the analysis phase, students compare and contrast their knowledge with other information, allowing them to question and test it The evaluation stage encourages students to argue, defend, and support their opinions on the information Finally, the synthesis level involves creating new projects, products, or perspectives based on their understanding.
Bloom's Taxonomy is a versatile framework applicable across various grade levels and subjects, enabling teachers to evaluate students based on diverse learning outcomes aligned with educational standards Each level of the taxonomy encompasses specific tasks that guide students through different cognitive processes An engaging activity illustrates how a single image can facilitate the achievement of all levels of Bloom’s Taxonomy To effectively incorporate this framework into lesson planning, educators should articulate their lessons using language that corresponds to each level of the taxonomy.
Toyota Vios electric power steering model
3.3.1 The structure about Toyota Vios electric power steering system
The Toyota Vios electric power steering model has been utilized in chassis practice workshops for an extended period, serving as a valuable teaching tool for lecturers However, many students still face challenges in grasping its structural and operational principles due to theoretical limitations during lectures To address this gap, we aim to provide a comprehensive understanding of the model, including its usage and diagnostic processes We will begin with a theoretical overview followed by practical exercises related to this specific model, enhancing students' learning experience.
Figure 3.2 Toyota Vios electric power steering model
Below is each important part to make up the electric power steering system available on the model
Table 3.1 Table of structural parts of Toyota Vios electric power steering model
Steering wheel Turning the guide wheels
The steering column plays a crucial role in transmitting torque from the steering wheel to the steering mechanism It features a lower section connected to the steering box via an elastic coupling, which effectively reduces vibrations from the road surface, ensuring a smoother driving experience.
Power steering motor Generate power assist from the signal of the EPS ECU sent to
Torque sensor Convert torque into electrical signal to EPS ECU
Dashboard Display the necessary parameters related to the system
EPS ECU Receive signal from the torque sensor and operate the power steering motor
Rackhousing Turn the guide wheel in the direction of steering wheel rotation
As automotive technology advances, vehicle operation often encounters issues, particularly system failures Recognizing the need for effective error testing and resolution, Techstream software was developed This innovative tool addresses contemporary automotive challenges and is designed to facilitate the learning process Techstream provides crucial insights into the electric power steering system, enabling students to easily access and resolve practical exercises.
Techstream software is an advanced automotive diagnostic tool designed specifically for Toyota, Lexus, and Scion vehicles It seamlessly integrates with other diagnostic systems, facilitating efficient car repairs Additionally, the Techstream tester features a multi-language application, enhancing user accessibility This article aims to demonstrate how to utilize Techstream software to effectively connect to the electric power steering system of the Toyota Vios, allowing users to monitor and analyze parameter changes within the system.
- Key features of Techstream test equipment
Techstream test equipment offers advanced features that enable quick identification of car makes and models while efficiently processing vehicle data Its software facilitates automatic connections to the vehicle's electronic systems, enhancing the diagnosis and resolution of any encountered issues.
• Read, detect and clear errors
The Techstream auto diagnostic system is essential for diagnosing vehicle issues, as it can read, check, and erase unnecessary error codes that may lead to malfunctions in the vehicle control system This capability enables technicians to accurately assess problems and provide prompt solutions, ensuring a safer driving experience for car owners.
Figure 3.5 Active test of Techstream
Car data is crucial for users, and Techstream testers enhance this experience by allowing the reading of essential parameters through graphs and numbers for better clarity This functionality enables Techstream diagnostic software to accurately identify the specifications of each vehicle model.
The Techstream software effectively activates safety systems across various car brands, including Toyota, Lexus, and Scion Its advanced capabilities enhance the vehicle control system, allowing for robust and efficient car fault diagnosis.
Techstream test equipment enables users to reset essential car systems, including memory, ABS system regulator, smart key, switch, and electronic steering system This functionality allows for easier and more proactive installation of parts, enhancing the overall user experience.
To get started, it's essential to install the necessary files and ensure you have a cable for connecting the Mongoose or Mini VCI to link the model with your laptop.
In here, we use Mongoose cable to connect:
• Techstream V12.00.127: https://drive.google.com/open?idyecO2aN1Oxgtzl- 1KOLR01DI7fEHMNT
• Driver Mongoose: http://data.oto- hui.com/files/2/qaif06pnnobjen/Driver_mongoose_full_pro_jlr_driver_disk_v_ 1.1.16.zip
Then we proceed with the installation according to the instructions below
Figure 3.6 Folder containing the downloaded file Run as Administrator
We click Next until Finish setup and then we must crack for this:
Copy file MainMenu.exe into file Techstream Follow link here: C:\Program Files (x86) \Toyota Diagnostics\Techstream\Bin
Choose “Replace the file in the destinatio
Figure 3.48 Replace file After that, turn-on Techstream on Desktop
Figure 3.49 Select area Now, we are seeing the display show the area selection, we continue select area Japan
When we choose Japnan area, we will see the background of picture, we Fill in the blanks in the following order:
Next, it will display here
Figure 3.151 Techstream's main interface After that, we click Setup -> Register Techstream Software
Figure 3.152 Register Techstream Software Fill Key in the space: 1111111111111111111111111111111150001511111111
Click OK You will have 5000 days to use this sofware After that, we got to install Driver Mongoose:
Figure 3.54 Folder containing the file Mongoose Let’s run as administrator
Figure 3.155 Proceed to unzip the file
We choose the language is Engilish and then click
We have to install device software and choose the right way and click “next” until the display “finish”
The last step, we need to adjust the driver in Techstream We will choose Setup and then choose VIM Select as the picture below
Figure 3.4 Installed software Done We have installed the software, now ready to use it
After installing the Techstream software, the next step is to connect it to the Toyota Vios model to learn about the system's key parameters Begin by supplying power from the vehicle's battery, then use the Mongoose cable to connect the laptop to the model's DLC3 port.
Figure 3.6 Connect Mongoose cable with model
To begin, switch the lock to the ON position, launch the software, and click on "Connect to vehicle." This will bring up the parameter selection screen, where you should choose the options displayed in the accompanying image.
Figure 3.7 Choose the right vehicle
Once selected, an overview interface of the car's systems will display, allowing us to check for any errors Specifically, for the electric power steering system, navigate to the "Chassis" section and select "EMPS."
Figure 3.8 Parameters of each system After selecting, we continue to select "DATA LIST", the window on the parameters of the electric power steering system will appear as shown below
Figure 3.9 Parameters of the electric power steering system of Toyota Vios
The values listed in the datasheet are crucial parameters for diagnosing the electric power steering system in this model Understanding these numbers is essential for identifying the system's symptoms and providing effective exercises for students to learn.
• When the steering wheel is in the middle position (no steering)
The torque output sensor value shows 3 output signal values: torque sensor 1, torque sensor 2, and Torque sensor 3 The above signals of each torque sensor are in the order 1,
In the central position without steering the wheel, the torque sensor values of 1 and 2 approximate the values of VT1 and VT2 However, when comparing the position of the third transmitter coil to the second, a slight variation in the passing flux occurs, resulting in a minor difference in the reading of Torque sensor 3 due to significant flux changes.
Figure 3.10 The graph shows the torque sensor value when the steering wheel is stationary
• When the steering wheel turns to the left:
Hydraulic power steering model
3.4.1 The structure of the model
The hydraulic power steering model has been a long-standing teaching tool in the workshop, designed to provide students with a detailed understanding of the system's structure, operating principles, and testing methods By using a miniature simulation, learners can effectively grasp the essential components of the model and their functions.
Figure 3.19 Hydraulic power steering models
Figure 3.20 The component of Hydraulic power steering system in model
Table 3.2 Table of structural parts of Hydraulic power steering model
Steering wheel Turning the guide wheels to the left or to the right
Oil tank Contains power steering oil to transfer to the power steering pump and is a place to store return oil
A/C motor It has the function of driving the power steering pump through the belt
Power steering pump The power steering pump helps to provide the necessary oil pressure to the hydraulic power steering system to operate
A/C main switch Power switch of the motor, when the switch is turned on, it will supply power to the motor and rotate the power pump through the drive belt
Rack housing is an essential component of power-assisted steering systems, featuring an oil reservoir that houses a power-assisted piston This piston plays a crucial role in directing the movement of the wheels, responding to the driver's steering input to enhance maneuverability and control.
The emergency button serves as the main switch for the air conditioning unit, allowing for immediate motor shutdown in the event of a problem It is specifically designed for easy activation and deactivation during emergencies.
Pressure Gauge Incoming oil pressure level display, unit (kg/cm2)
Adjust oil valve Close or open the oil line from the reservoir to the power steering pump
3.4.2 Procedure for checking the hydraulic power steering system model
Regularly check the belt tension, as prolonged use can lead to stretching, causing the belt to slip and negatively impacting motor performance To maintain optimal functionality, it's essential to periodically measure the belt tension on this model.
“DENSO belt tension gauge” device
• Standard belt tension value (4A-F, 4A-FE)
• Steps to perform belt tension test:
+ Step 1: Reset the gauge to the value 0 N
To ensure accurate measurement of belt tension, clip the ruler to the center of the belt, avoiding areas near the pulley where tension is high.
+ Step 3: Take the gauge off the belt and see the belt tension value
Figure 3.22 Measured value of the belt on the model
To measure the tension on the belt, we obtained a value of 350N Considering the length of the belt for this model, it remains in good condition compared to the standard value.
- Check the oil level before operation
Before starting the engine, ensure to check the oil level in the tank by opening the oil tank cap If the oil is below the standard level, add more power steering oil, ensuring that the oil is clean and not contaminated.
To ensure optimal performance of your vehicle's power steering system, begin by starting the engine and turning the steering wheel fully to the left and right This action allows the power steering oil to circulate and reach the necessary working level It's important to maintain a minimum oil temperature for effective operation.
• Close the pressure check valve and steer all the way to the right and left
• Check the pressure value displayed on the gauge
For this test, when steering all the way to the left or all the right, the average pressure value must be more than 65kg/cm 2 )
- How to change power steering oil
• We proceed to remove the return line from the tank and drain the oil into the tray
To begin the process, start the car and fully turn the steering wheel to the right and then to the left, allowing the oil to drain from the tray before shutting off the engine.
To effectively change your engine oil, pour fresh oil into the reservoir and start the engine, allowing the old oil to drain from the tray Turn off the engine and repeat this process 2-3 times until all air bubbles in the oil have dissipated.
• Insert the return oil pipe into the tank
To ensure proper oil circulation, start the engine and turn the steering wheel side to side 3-4 times to expel any trapped air from the system Afterward, check the oil tank to confirm that there is no air present.
To initiate the hydraulic power system model, first ensure all necessary requirements are met Begin by powering the motor and switching the A/C main switch to the ON position, which activates the motor and engages the power pump.
To ensure the hot oil reaches the optimal working level, we begin by steering fully to the left and right twice After unlocking the oil control valve, we note that the oil pressure is approximately 22 Kg/cm² while the engine is idling.
When the valve is opened and the steering wheel remains stationary, the pressure gauge indicates that oil pressure rises to approximately 80 Kg/cm² when the steering is fully turned left or right, a level that is considered safe and undamaging.
Figure 3.25 Pressure when the valve is unlocked, and the steering wheel turns all the way to the left or right
Students can effectively self-diagnose issues when the steering oil pressure drops below 65 kg/cm² or when the valve is locked, leveraging the theoretical knowledge they've acquired.
Building Excercise
Figure 3.26 Outcome standards Practice of Automotive Braking, Suspension and Steering
This article utilizes the Bloom cognitive scale and subject output standards to develop exercise forms for two models: the Toyota Vios electric power steering system and the hydraulic power steering system The Bloom scale illustrates the progression of students' understanding, from basic memory recall to higher-order thinking skills, aligning with the specific output requirements of each subject Students are expected to grasp the structure and concepts of each system component By analyzing essential elements, we design suitable exercises that correspond to each lesson's content while adhering to workshop models The exercises are categorized according to the Bloom scale, ensuring a structured approach to learning.
Figure 3.27 The type of exercise corresponds to each level of the Bloom scale
Each exercise level is designed to ensure that students acquire essential knowledge, including understanding structures, presenting operational principles, collaborating effectively in groups for advanced tasks, and applying their knowledge to troubleshoot issues Subsequently, the article outlines methods for developing exercises tailored to each specific level.
Students must understand the structure of the two system models, including the components and their locations, as well as the methods for accessing them The initial exercise will utilize a detailed list of structural images to facilitate this learning.
Figure 3.5.3 Each part of the electric power steering system
Incorporating images into exercises enhances students' understanding of the shapes and positions of components within the power steering system These exercises emphasize identifying the names and locations of each part, providing detailed visuals of both electric and hydraulic power steering systems Students are tasked with naming each component and pinpointing its location within the overall system.
Figure 3.5.4 Sample exercise to learn about the name and function of the part on the system
This exercise focuses on enhancing understanding of a system by having students recall the location and image of each component Participants will fill in the positions of these parts on a comprehensive system overview, promoting better comprehension To elevate the challenge, six arrows will be provided, each linked to a specific part, along with suggested names to reinforce students' grasp of the system's structure An illustration of this exercise is included below.
Figure 3.5.5 Type of exercise to arrange the position of each part on a large system
This article emphasizes the importance of organizing the components of both electric power steering and hydraulic power steering systems to gain a comprehensive understanding of their overall structure By visually examining images of each part, readers can enhance their memory retention, resulting in a longer-lasting recall of the information.
To effectively design this type of exercise, students must first grasp the underlying theory and general structures of the model, allowing them to advance their understanding to a more sophisticated level.
+ Describe the operating principles of each part of the system
To align with the output standards of G4.1 and the Bloom scale, students will engage in an essay exercise that explores the operational principles of each component within the system This foundational task will facilitate a comprehensive understanding of the entire system's functionality and illustrate the interconnectivity of its parts, requiring students to effectively present the operational principles of each segment.
The electric power steering system operates through an electric motor and a torque sensor, which work together to enhance steering performance This system utilizes the torque sensor to detect the driver's steering input and adjusts the motor's output accordingly, providing the necessary assistance By understanding the function of each component, users can grasp the overall operating principle of the electric power steering system Exercises will be provided to reinforce the application and functionality of these parts, summarizing their roles in the system's operation.
For hydraulic power steering system: Presenting the general operating principles of hydraulic power steering system, working principle of rotary pump, direction of oil movement based on control valve image
3.5.4 Apply level and Analyze level
The level of application and analysis will require students to perform and solve problems on the model when encountering failures on the system
To fulfill the requirements of G4.1 and G3.2, exercises should focus on enabling students to utilize models effectively, diagnose real errors within these models, and analyze the underlying causes of these mistakes.
Students engage in practical exercises on the electric power steering system by working in groups to disassemble the torque sensor mechanism They identify the type of torque sensor utilized in the model and use Techstream software to independently read and analyze the parameters, demonstrating how these parameters change during operation.
This section offers various exercises that allow students to engage directly with the model while collaborating in groups, enhancing their teamwork skills Collaborative efforts facilitate debates and generate diverse ideas, leading to a deeper understanding of the system.
Result of Exercise for practice
- Type of exercise of Electric power steering model
Table 3.3 Questionnaire of exercises for students on toyota vios electric power steering model
Content of exercises Output standard
1 Present the general working principle of electric power steering system (EPS)?
2 Which is correct about electronic power steering?
A At low speed, the steering force is higher than normal speed
B At low speed, steering force is lower than normal speed
C At high speed, the steering force is higher than normal speed
D At high speed, the steering force is lower than normal speed
3 State the position and function of the power steering motor?
4 Fill in the components of an electric power steering system
5 Present the concept, requirements and classification of electronic power steering system?
6 State the difference between C-EPS and D-EPS settings
7 Presenting the structure of the torque sensor G4.1 1
8 Based on the voltage and torque graph No 1 and 3, analyze the cause of the voltage difference and why sometimes the difference is large and sometimes the difference is small
9 Compare electric power steering system and hydraulic power steering system?
10 When turning the steering wheel, it feels heavy and powerless, what are the reasons?
11 From the parameters displayed on Techstream, why when turning the steering wheel to the right, the
Torque Sensor Output value is greater than 2.5A and vice versa?
12 Difference between Steering angle sensor and
13 Fill in the blanks in the correct order
• Exercise Group practice exercises at the applied level: Students divide into groups and use Techstream software to measure and record the following parameters
Table 3.4 Practice sheet using Techstream to measure parameters
Parameter Measuring condition Measured value
TRQ1 Output Value Turn the steering wheel to the left
Turn the steering wheel to the right
TRQ2 Output Value Turn the steering wheel to the left
Turn the steering wheel to the right
TRQ3 Output Value Turn the steering wheel to the left
Turn the steering wheel to the right
Motor Actual Current Turn the steering wheel to the left
Turn the steering wheel to the right
Command Value Current Turn the steering wheel to the left
Turn the steering wheel to the right
Motor Terminal Volt (+) Turn the steering wheel to the left
Turn the steering wheel to the right
Motor Terminal Volt (-) Turn the steering wheel to the left
Turn the steering wheel to the right
PIG Power Supply Turn the steering wheel to the left
Turn the steering wheel to the right
IG Power Supply Turn the steering wheel to the left
Turn the steering wheel to the right
- Exercise form of Hydraulic power steering
Table 3.5 Questionnaire of exercises for students on hydraulic power steering model
Content of exercises Output standard
1 State the possible causes when the steering wheel returns slowly
2 The vane pump (power steering pump) makes a noise when turning the steering wheel, what is the cause?
3 Why when starting the engine, the rpm will jump to about 1000 rpm and then back to 700-800 rpm?
4 Driving to the left is heavier than when hitting to the right What is the cause?
5 Students should follow the steps below to test the hydraulic power steering model before operation
6 Fill in the appropriate phrases for each part G4.1 1
7 When and how will the safety valve work? G4.1 2
8 Summarize the steps of the general operating principle of the hydraulic power steering system?
After powering on the model, switch the control knob between "OPEN" and "CLOSE" modes to observe the differences between them Understanding these variations is crucial for grasping the functionality of the device.
After powering on the model, turn the steering wheel fully to the left or right and hold it for 3 to 4 seconds before proceeding with the next steps.
- Observe the change in readings on the pressure gauge and interpret
- If turn the steering wheel all the way to one side and then hold it for 10 to 15 seconds, will there be any harm? Why?
- After answering the above two points, give some advice to the driver to reduce damage to the steering system
11 Basic steps to change the power steering fluid
Why do you need to change the power steering fluid?
12 If on the model, we steer to the left or right, the oil pressure is below 65kg/cm2, what is the reason
13 When the power steering oil in the reservoir is low
So what are the symptoms that the car encounters?
15 Why do small cars (under 7 seats) often use electric power steering, while large trucks use hydraulic power steering?
3.6.2 The reference answers for the above exercises
- Toyota Vios Electronic power steering system model
● Exercise 1 Present the concept, requirements of electric power steering system?
Electronic power steering minimizes the effort required for steering, alleviating driver fatigue during long journeys It enhances safety, particularly at high speeds, by aiding vehicle control in situations like tire blowouts or loss of tire pressure, while also dampening vibrations transferred from the wheels to the steering wheel.
To enhance ride comfort, modern vehicles often utilize wide, low-pressure tires that expand the contact area with the road, necessitating a greater driving force To mitigate steering effort, increasing the gear ratio in the steering mechanism can be beneficial, but this approach demands more steering wheel rotation during turns, making sharp maneuvers challenging Therefore, to maintain responsive steering with minimal effort, the integration of power steering is essential.
Power steering should provide minimal control force on the steering wheel rim to ease the effort required for turning, while still offering sufficient feedback to ensure the driver feels in control.
+ When the power steering system fails, the steering system can still be controlled like a normal mechanical steering system
+ The structure of the power steering system must be simple, easy to take care of, maintain and repair
+ Ability to manually rotate the steering wheel to the original position
● Exercise 2 Compare electric power steering system and hydraulic power steering system?
The Hydraulic Power Steering (HPS) system operates independently from the steering mechanism, requiring a dedicated power source that includes components like hydraulic pumps, cylinders, valves, and oil lines The complexity of designing HPS is significant due to the extensive equipment needed, making it challenging to install in compact vehicles.
The high-precision manufacturing required for hydraulic power steering (HPS) systems is crucial, as any issues can lead to increased driver effort due to fluid resistance Additionally, the reliance on power steering oil presents environmental concerns, particularly during maintenance when oil replacement and repairs can release harmful substances into the environment.
The EPS power steering system features a compact design, consisting of a DC electric motor and an EPS ECU, making it easy to install and highly efficient This system only consumes energy when needed, unlike hydraulic power steering (HPS) systems that operate continuously, even when not required By utilizing clean energy and minimizing waste, the EPS system enhances fuel efficiency for vehicles, presenting a significant improvement over traditional oil power steering systems.
● Exercise 3 Present the general working principle of electric power steering system (EPS)?
Based on the operation of EPS, its working principle is divided into the following 6 steps:
+ Step 1 Power steering will start working when the driver applies force to turn the steering wheel
When force is applied to the steering wheel rim, it causes the torsion bar in the steering gear to twist The torque sensor measures the angle of rotation of the torsion bar and transmits the calculated steering force signals to the ECU.
+ Step 3 From the current torque and steering speed sensor, it will be sent to the EPS ECU
+ Step 4 Based on steering force, movement speed, engine speed, steering angle, steering speed in the ECU The EPS ECU calculates the power required to control the electric motor
+ Step 5 The motor's power steering will act on the steering mechanism with an appropriate power to help the driver rotate the steering wheel gently
● Exercise 4: Presenting the structure of the torque sensor
The system consists of an input shaft connected to the steering wheel and an output shaft linked to the steering mechanism, with a torsion bar connecting the two An induction ring with grooves is mounted on the input shaft, designed to fit with the teeth of a second induction ring Additionally, a third induction ring featuring teeth and grooves is installed on the output shaft Surrounding these induction rings are two coils: a detection coil and a correction coil.
● Exercise 5: State the difference between C-EPS and D-EPS settings
+ C-EPS: The power steering unit is located in the driver's cabin, suitable for cars with a small engine compartment, the power steering motor is located on the steering shaft
+ D-EPS: Power steering is located inside the engine compartment, power steering motor is located right in the steering mechanism, often used on mid-sized cars
● Exercise 6: When turning the steering wheel, it feels heavy, what are the reasons?
+ Damaged torque sensor (cannot measure the force and direction of rotation of the steering wheel, so the signal cannot be sent to the EPS ECU)
+ Power assist motor is damaged (powered but not working)
+ The battery power supply unit has a problem
● Exercise 7: State the position and function of the electric motor
+ Location: located right on the steering shaft
+ Function: receive signals sent back from the ECU, thereby assisting the driver to turn the steering wheel lighter
● Exercise 8: From the parameters displayed on Techstream, why when turning the steering wheel to the right, the Torque Sensor Output value is greater than 2.5A and vice versa?
When the steering wheel is turned to the right, the torsion bar in the steering mechanism rotates, causing a change in position between emitter 2 and emitter 3 In this intermediate position, the voltage measures 2.5A, resulting in a larger gap that allows more magnetic flux to pass through, increasing the voltage above 2.5A Conversely, turning the steering wheel to the left reduces the gap, leading to a voltage drop below 2.5A.
● Exercise 9: Difference between Steering angle sensor and Torque sensor
The layout of the steering system includes the steering angle sensor positioned near the steering wheel rim, while the torque sensor is partially situated on the torsion bar and the output shaft (pinion shaft) To effectively measure torque, the torque sensor must be configured along two axes.
The steering angle sensor measures the position of the steering wheel, while the torque sensor not only monitors the steering input but also detects feedback from the road surface acting on the steering system.
● Exercise 10: Which is correct about electronic power steering?
A At low speed, the steering force is higher than normal speed
B At low speed, steering force is lower than normal speed
C At high speed, the steering force is higher than normal speed
D.At high speed, the steering force is lower than normal speed
Electronic power steering enhances vehicle safety at high speeds by increasing the steering force, which helps prevent driver carelessness This heavier steering response ensures better control, while at lower speeds, a lighter steering force is implemented to provide a more comfortable driving experience.
● Exercise 11: Which signal is not an input signal in the electronic power steering system?
D the input signal of the electric power steering system includes 3 signals: torque sensor, vehicle speed, steering angle
● Exercise 12 Fill in the components of an electric power steering system
Analyzing the voltage and torque graphs reveals that the voltage difference can vary significantly due to factors such as load conditions, motor efficiency, and operational speed When the load on the motor increases, it often results in a larger voltage difference due to the increased torque demand Conversely, under lighter loads, the voltage difference tends to be smaller as the motor operates more efficiently Understanding these variations is crucial for optimizing motor performance and ensuring reliable operation.