Car Maintenance Basics

Chapter 11 Project Five Automobile Testing Equipment (1)
[-] engine testing equipment

learning purpose

Knowledge goal:

Learn about the types of automotive engine testing equipment.

Master the basic knowledge of automotive engine testing equipment.

Master the use of automobile engine testing equipment.

Skill Goal:
Automobile engine testing equipment will be used to test the engine.

Proficiency in operating automotive engine testing equipment.

Gain the skills to perform car repairs using car repair equipment.

Under the guidance of relevant knowledge, understand the basic knowledge and technical requirements of commonly used equipment for automotive engine testing.Under the guidance of the work order task, the engine testing equipment can be used for engine testing.By learning and mastering the operation skills of automobile engine testing equipment, record and archive the completed work, and consciously maintain safe operation and 5S work requirements.

related information
[-]. Engine no-load dynamometer
The no-load dynamometer can be made into a single-function portable dynamometer, and can be combined with other test instruments to become a desktop engine comprehensive tester.The method of using the no-load dynamometer is as follows:

1. Instrument self-calibration and preheating

According to the instruction manual, the instrument is preheated for 0.5h, and then performs self-calibration (the panel diagram is shown in Figure 5-1).Turn the counting check knob 1 to the "check" position, and the pointer on the left time (T) meter will swing once for 1s.Turn the knob 1 to the "test" position, turn the knob 3 to the "self-calibration" position, and then slowly turn the "simulation speed" knob 2, and notice that the pointer of the speed () gauge slowly deflects to the right (simulation increases the speed).When the pointer deflects to the position of the starting speed of 1000r/min, the door control indicator light will be on.Continue to increase the simulated speed to n = 2800r/min, the "Le" meter will indicate the acceleration time to indicate the speed of the simulated speed.Press the "Reset" button, the hands of the instrument will return to zero, and the door control indicator light will go out, indicating that the instrument is adjusted normally.Otherwise, trim the heart 2 potentiometer.

2. Preheat the engine and install the speed sensor
Warm up the engine to normal operating temperature (85-95°C) and allow the engine to idle at normal speed.Put the transmission in neutral, and then connect the two wiring cards of the speed sensor of the instrument to the low-voltage terminal of the distributor and the iron line respectively.

3. Measure acceleration time

The operator quickly depresses the accelerator pedal to the bottom in the cab, and the engine speed suddenly rises.When the pointer of the "T" meter shows the acceleration time (or power), the accelerator pedal should be released immediately, and the engine should not be idling at high speed for a long time.Write down the reading and reset the instrument to zero.The operation was repeated three times, and the readings were averaged.

A pocket-sized no-load dynamometer with a telescopic antenna that can receive ignition pulse signals when the engine is running without any wired connection to the engine.When in use, hold the dynamometer by hand, just pull out the telescopic antenna facing the side of the engine, and the engine suddenly accelerates to run, and the acceleration time and rotational speed can be measured remotely.Then turn over the dynamometer and check the power and time comparison table of the main models printed on the back of the shell to know the power of the engine.Many no-load dynamometers are also equipped with sensors for detecting diesel engines in order to detect the power of diesel engines.

[-]. Engine sealing test equipment

1. Cylinder pressure gauge

The cylinder pressure gauge is shown in Figure 5-2.Because the cylinder pressure gauge detects the compression pressure of the cylinder, it has the advantages of low price, light and handy instrument, strong practicability and convenient detection, so it is widely used in automobile maintenance enterprises.Its usage is as follows:

The engine is running normally, so that the water temperature reaches above 75C.After shutdown, remove the air filter, blow off the dust and dirt around the spark plugs or fuel injectors with compressed air, then remove all the spark plugs or fuel injectors, and place them in the order of the cylinders.For gasoline engines, the high-voltage wire of the central electrode of the distributor should also be unplugged and reliably grounded to prevent electric shock and fire. Then insert the rubber joint of the cylinder pressure gauge into the spark plug hole of the cylinder under test, and press it tightly.Put the throttle valve and choke valve in the fully open position, use the starter to rotate the crankshaft for 52-3s (not less than four compression strokes), and stop the rotation after the pointer of the pressure gauge head indicates and maintains the maximum pressure.Take down the cylinder pressure gauge, write down the reading, and press the one-way valve to make the pointer of the pressure gauge return to zero.Measure each cylinder sequentially according to the above method, and the number of measurements for each cylinder shall not be less than twice.

2. Crankcase blow-by gas measuring instrument

The LQC-H crankcase blow-by gas measuring instrument is shown in Figure 5-3.Its usage is as follows:

①Turn on the power switch, and pre-adjust the detector according to the requirements of the instrument manual.

②Seal the crankcase, that is, block the oil gauge opening, crankcase ventilation inlet and outlet, etc., and insert the sampling probe into the oil filling port.

③Start the engine, and after it runs stably, the indicated value of the meter in the instrument box is the blow-by gas volume of the engine crankcase at this speed.

The amount of blow-by gas in the crankcase is not only related to the technical condition of the engine cylinder piston group, but also related to the engine speed and load.Therefore, when testing, the engine should be loaded, the throttle valve is fully open (or the maximum fuel supply of the diesel engine), and the test is performed at the maximum speed (the amount of blow-by gas is the largest at this time).The engine loading can be realized on the chassis dynamometer. The loading device of the dynamometer can easily load the engine through the drum, the driving wheel and the transmission system. run at high speed.Therefore, the crankcase blow-by gas volume detector can be used to detect the crankcase blow-by gas volume under various working conditions.

[-]. Endoscopy
Automotive electronic endoscope (Figure 5-4) is an electronic endoscope specially designed for the automotive maintenance industry, mainly used for detection and diagnosis of automotive engines, cylinders, gearboxes, differentials, fuel pipes, engines, mufflers, and delivery systems , Water tank, fuel tank carbon deposition, blockage, wear and so on.When a car engine fails, the original diagnosis method is to judge the problem of the cylinder based on experience and listening to the sound. The specific cylinder needs to be disassembled to determine it; The fuel injector can directly inspect the carbon deposits and foreign objects inside the cylinder as shown in Figure 5-4, which improves work efficiency, reduces repair costs, and avoids repeated disassembly and assembly of parts. damage caused.

It has the characteristics of small and portable, clear image, thin diameter, swingable head, video recording and storage, and connection with computer.At the same time, with the help of corresponding image processing software, call at any time, slow down, partially zoom in, and interpret specific image frames to create electronic maintenance files, which serve as a powerful basis for charging and avoiding consumer disputes.

[-]. Engine tachometer
The digital flash tachometer is shown in Figure 5-5.Its usage is as follows:

① Make an eye-catching mark on the measured object away from the axis.

②Insert the socket of the flashlight cable into the socket of the instrument.

③ Turn on the power and preheat for 5 minutes to stabilize the frequency.And do not turn on the flash.

④ Self-calibration of the instrument according to the instruction manual.

⑤ According to the rotational speed range of the measured object, gradually reduce the flash frequency from high speed until a single stroboscopic image appears.If necessary, use 2 times the frequency to check whether there is a double stroboscopic image, that is, the stroboscopic image presents 2 stroboscopic points.

⑥When the strobe image moves slowly to the left and right, it means that the flash frequency is not equal to the rotational speed of the measured object.If the flash frequency is lower than the rotational speed of the object, the moving direction of the stroboscopic image is the same as the rotational direction of the object, and the frequency can be fine-tuned until the flash frequency is equal to the rotational speed of the rotating object, and a single stroboscopic image is obtained.

[-]. Engine Comprehensive Performance Analyzer

Kinder K100-B Engine Comprehensive Performance Analyzer is shown in Figure 5-6, it can collect ignition, fuel injection, and electronic control system sensor waveforms in real time.Through the analysis of the sensor waveform, the sensor fault can be accurately diagnosed.Through the analysis of the ignition waveform, it is possible to diagnose the failure of various components such as the spark plug, high-voltage line, and ignition ring of the ignition system, and also analyze the failure points of the air intake system and the fuel system, providing a scientific synthesis for the technical status and fault diagnosis of the vehicle. Basis for Performance Analyzer.

task implementation
According to the guidance of the work order, complete the operation of the common equipment used in automobile maintenance equipment.In the process of task implementation, they will learn the operating procedures and maintenance methods of automobile maintenance equipment, and implement them in groups to complete the work within the specified time.

[-]. Tool preparation

Tip: Before implementing the homework, each group should prepare the materials and tools needed for this learning task according to the table below.

Data, number of names of tools Data, number of names of tools
One engine training bench One engine comprehensive analyzer

One set of common tools for engine no-load dynamometer

Engine cylinder pressure gauge set

[-]. Technical standards and requirements
① All operations meet the requirements for safe operation.

②All operations conform to the operating procedures of automobile maintenance equipment.

③ Safety accidents are not allowed during the operation.

[-]. The work to be done

1. Test the power of the engine with a no-load dynamometer

For the operation steps, refer to the content in the relevant knowledge, and record the test data.

2. Use the cylinder pressure gauge to measure the cylinder pressure. For the operation steps, refer to the equipment instruction manual and fill in the table below.

3. For the operation steps of the engine comprehensive performance analyzer, please refer to the relevant instructions.

① Please point out how many main functions does the decoder used have?
② What is the practical significance of the dynamic data stream read by the decoder for the maintenance of the automotive electronic control system?
[-]. Training report

The use method and operation steps of no-load dynamometer, cylinder pressure gauge, engine comprehensive performance analyzer and other equipment.

learning assessment
[-]. Self-evaluation

1. Summary What are the main testing equipment for automobile engines?

2. Please write down your experience of this learning task.

3. Self-evaluation of the learning environment (including dress, learning attitude, mastery of knowledge and skills, completion of work pages, etc.).

[-]. Group evaluation

Evaluation status of serial number evaluation items
Good to bad

1 team spirit
2 Whether learning is proactive
3 The situation of obeying the work arrangement

4 Use of tools and instruments
5. Tool finishing and site cleaning
[-]. Teacher Evaluation

Evaluation status of serial number evaluation items
Good to bad

1 Attendance
2 dressing situation

3 classroom order
4 Whether learning is proactive
5. Fill out the learning task book

6 Use of tools and instruments
7. Tool finishing and site cleaning
Second chassis testing equipment

Learn
Knowledge goal:

Learn about the types of automotive chassis testing equipment.

Master the basic knowledge of automobile chassis testing equipment.

Master the use of automobile chassis testing equipment.

Skill Goal:
Can operate automobile chassis testing equipment.

Can use four-wheel aligner.

Under the guidance of relevant knowledge, understand the basic knowledge and technical requirements of automobile chassis testing equipment.Under the guidance of the work order task, the automobile chassis inspection equipment can be used to inspect the automobile.By learning and mastering the operation skills of automobile chassis testing equipment, record and archive the completed work, and consciously maintain safe operation and 5S work requirements.

Related Knowledge Steering System Testing Equipment

The steering force-steering angle detector of the automobile steering wheel is shown in Figure 5-7.The method of use is as follows: when measuring, align the steering parameter measuring instrument with the center of the steering wheel under test,

Adjust the length of the telescopic claws on the three connecting forks, connect and fix them with the steering wheel.Turn the steering wheel, and the steering force is transmitted to the steering wheel under test through the base plate, torque sensor, and connecting fork, so that the steering wheel turns to realize the steering of the car.At this time, the torque sensor converts the steering torque into an electrical signal, and the photoelectric device connected to the inner end of the positioning rod converts the change of the rotation angle into an electrical signal.These two electrical signals are automatically completed by the microcomputer for data collection, corner coding, calculation, analysis, storage, display and printing.Therefore, the measuring instrument can measure not only the steering force of the steering wheel, but also the amount of free rotation of the steering wheel.

[-]. Suspension system testing equipment

1. Suspension steering system clearance tester
Suspension steering system gap tester is shown in Figure 5-8.

①The front axle of the car is placed on the test board of the suspension device and the steering clearance tester, and the two front wheels are parked in the middle of the two test boards.

②The driver of the car firmly steps on the brake pedal and holds the steering wheel firmly.The under-vehicle inspector presses the "front and rear direction movement" button on the upper test board of the flashlight switch to make the suspension device and the steering system move forward and backward repeatedly at a certain frequency.

③The inspector under the vehicle presses the “left and right movement” button on the test board on the flashlight switch to make the suspension device and the steering system move left and right repeatedly at a certain frequency.

④ The inspector under the vehicle presses the “move in front left and rear right (diagonal)” keys or the “move in front right and rear left (diagonal)” keys on the test board on the flashlight switch to make the suspension device and The steering system repeatedly moves in front left and rear right (diagonal) directions or moves in front right and rear left (diagonal) directions at a certain frequency.

⑤ When the front axle of the car is tested for the above moving direction, the inspector under the car should always pay attention to observe, and touch the car wheel and brake floor, steering knuckle king pin, longitudinal and horizontal tie rod ball joint pin, independent suspension with hands Record the gaps at the swing arm, the U-shaped bolts of the relevant suspension, the steel plate pins, the steering drop arm and the fixing of the steering gear, and make adjustments or repairs as necessary.

⑥The driver loosens the steering wheel and the brake pedal, drives the front axle down and the rear axle up, and uses the same method to detect the gap between the rear axle suspension device and the steering system on the test board.

⑦ After the detection is completed, turn off the flashlight switch and the main power supply of the electric control box.

2. Automobile suspension device test bench
The vehicle suspension device test bench is shown in Figure 5-9.Its usage is as follows:

When testing, drive the car onto the support platform, start the test program, and drive the motor to drive the eccentric mechanism to vibrate the entire car surface system.After the excitation reaches a stable forced vibration with an angular frequency of Kiss for a few seconds, the power supply of the drive motor is disconnected, and then the energy storage flywheel performs frequency sweep excitation with the initial frequency as the angular frequency of Kiss.Since the natural frequency of the wheel parked on the platform is between 0 and [-], the frequency sweep excitation of the energy storage flywheel can always make the vehicle's platform system resonate.While disconnecting the power supply of the driving motor, start the sampling test device, record the data and waveform, and then analyze, process and evaluate.

[-]. Wheel alignment testing equipment

The four-wheel aligner is shown in Figure 5-10.Its usage is as follows:

1. Basic requirements for inspected vehicles

When testing the alignment of the front wheels of a car, the vehicle to be checked shall meet the following requirements:
① The air pressure and tread wear of the front and rear tires are basically the same.

②The components of the front and rear suspension systems are in good condition and not loose.

③The steering system is properly adjusted and not loose.

④ Front and rear shock absorbers have good performance and no oil leakage.

⑤ The difference between the front and rear height of the vehicle and the standard value is not greater than 5mm.

⑥The braking system is normal.

2. Preparation before testing
① Drive the car onto the lifting platform, hold up the four wheels, and lift the car by 0.5m (the first lift).

②Hold up the appropriate parts of the body and lift the car until the wheels can rotate freely (the second lift).

③Remove each wheel and check the tire wear.

④ Check the tire pressure, inflate or deflate if it does not meet the standard.

⑤ Do the dynamic balance of the wheel.After the dynamic balance is completed, the wheels are assembled.

⑥ Check the height of the vehicle body, check the height of the four corners of the vehicle body and the technical condition of the shock absorber. If the body is not level, level it first; at the same time, check whether the steering system and suspension are loose. If they are loose, fasten or replace parts first.

3. Detection steps

① Install the sensor bracket on the rim, then install the sensor (positioning correction head) on the bracket, and adjust according to the regulations in the instruction manual.

②Start the machine and enter the test program, and enter the model and production year of the car being checked.

③Rim deformation compensation.The steering wheel is located in the straight-ahead position, so that each wheel rotates once, and the deformation error of the rim can be input into the computer.

④Reduce the second lift to make the wheels fall on the platform, and press the front and rear of the car down 4-5 times to make it bounce under pressure.Depress the brake pedal with the brake lock to put the car under the brakes.

⑤Turn the steering wheel to the left until the computer makes an "OK" sound, and enter the left turn angle; then turn the steering wheel to the right until the computer makes an "OK" sound, and enter the right turn angle.

⑥Turn the steering wheel back upright, the toe-in and camber values ​​of the rear wheels will be displayed on the computer screen, adjust the steering wheel, and lock the steering wheel with the steering wheel lock so that it cannot rotate.

⑦ Adjust the level of the positioning correction head installed on the four wheels to the horizontal line. At this time, the values ​​of caster angle, kingpin inclination angle, steering wheel camber angle and toe-in of the steering wheel are displayed on the computer screen.

⑧Adjust caster angle, camber angle and toe-in. The adjustment method can be carried out according to the prompts on the computer screen.If the problem still cannot be solved after adjustment, the relevant parts should be replaced and a second pressure bounce should be performed.Turn the steering wheel left and right, press down the body repeatedly, and observe whether the value on the screen changes. If the value changes, it should be adjusted again.

⑨If no problem is found in the second inspection, the part that was loosened during adjustment should be tightened.

⑩Remove the alignment correction head and bracket, conduct a road test, and check the four-wheel alignment detection and adjustment effect.

[-]. Side slip test bench
The sideslip test bench is shown in Figure 5-11.Its usage is as follows:

Different models and specifications of sideslip test benches have different usage methods, so be sure to read the instruction manual carefully before use.Usually, the sideslip test bench is used as follows:
1. Preparation before measurement
① Before the test bench is used, the test bench should be checked, and it can be used only after all parts work normally.

② The inspected vehicle should also be inspected, and the tire pressure must be checked to meet the regulations, in case the left and right tire pressures are not equal to cause the car to deviate and affect the measurement.For the surface of the tire, remove the stones and dirt in the pattern, keep the tread dry, and prevent the tire from sliding on the side skateboard.

2. Measurement steps
① Pull out the locking pin of the side slide and turn on the power.

②The car drives straight along the test bench at a low speed (4km/h).

③ When the wheel to be tested passes through the test bench completely, read the maximum indication value of the indicator (pay attention to the side slip direction, "N" means the wheel is slipping outward, and "OUT" means slipping inward).

④ After the test is completed, cut off the power supply and plug in the locking pin of the side slide.

[-]. Wheel balance testing equipment

(End of this chapter)