A vehicle test method for the maximum boost pressure of a brake vacuum booster

Abstract

The present invention is a method for testing the maximum boosting pressure of a brake vacuum booster on a whole vehicle. The method includes: First, ensuring that the engine of the test vehicle is normal, the pipelines are normal, the vehicle vacuum sensor, the master cylinder pressure sensor, and the CAN bus signal are normal; Second, connecting the CAN bus signal acquisition device, starting the engine, observing the change of the vacuum sensor signal. After the vacuum signal stabilizes again, starting the device to record the CAN signal and preparing to start the test; Third, when the brake pedal is depressed, the vacuum gradually decreases, and during the process of releasing the brake pedal, the vacuum gradually increases. Continuing to release the brake pedal will cause the vacuum to suddenly decrease. Record the lowest level of the vacuum at this moment and the corresponding master cylinder pressure level. The present invention can measure the maximum boosting pressure of the vacuum booster on the whole vehicle by using the existing CAN bus signal on the vehicle without connecting additional pedal force sensors and brake pressure sensors, thereby improving the test efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of automobiles, and specifically relates to a method for testing the maximum boost pressure of a brake vacuum booster on a whole vehicle. Background Art

[0002] At present, the braking systems of passenger cars generally adopt vacuum servo-assisted hydraulic systems. Among them, the technical parameters of the brake vacuum booster have a great influence on the performance of the braking system, and the maximum boost pressure of the vacuum booster is closely related to the braking efficiency level. During test development and problem-solving, it is often necessary to measure the maximum boost pressure of the vacuum booster on the whole vehicle; usually, when testing the maximum boost pressure of the vacuum booster on the whole vehicle, it is necessary to add a pedal force sensor and a brake pressure sensor to the test vehicle, which requires professional test equipment, affects the test efficiency, and reduces the work mobility. Summary of the Invention

[0003] To solve the above problems, the present invention provides a method for testing the maximum boost pressure of a brake vacuum booster on a whole vehicle, which can measure the maximum boost pressure of the vacuum booster on the whole vehicle by using the existing CAN bus signals on the vehicle without connecting additional pedal force sensors and brake pressure sensors, thereby improving the test efficiency.

[0004] The technical solution of the present invention is described in conjunction with the accompanying drawings as follows:

[0005] A method for testing the maximum boost pressure of a brake vacuum booster on a whole vehicle includes the following steps:

[0006] Step 1: Test preparation;

[0007] Step 2: Test;

[0008] Step 3: Post-test processing.

[0009] Further, the specific method of the first step is as follows:

[0010] Determine that the engine of the test vehicle is normal; determine that the pipeline is normal; determine that the whole vehicle vacuum sensor, master cylinder pressure sensor and CAN bus signal are normal.

[0011] Further, determining that the engine of the test vehicle is normal includes determining that the engine of the test vehicle can start and run normally, there is no engine fault alarm on the whole vehicle, and there is no abnormal noise and vibration when the engine is running.

[0012] Further, determining that the pipeline is normal includes determining that the pipeline connection between the vacuum booster and the engine is normal, without blockage or air leakage.

[0013] Further, the signals of the master cylinder pressure sensor and the CAN bus signal are normally read through a data acquisition device.

[0014] Further, the specific method of step two is as follows:

[0015] Connect the CAN bus signal acquisition device, start the engine, wait for 1 min until the signal of the vacuum degree sensor in the vacuum chamber of the vacuum booster is stable, step on the brake pedal and then release the pedal, observe the change of the signal of the vacuum degree sensor, and start the device to record the CAN signal after the vacuum degree signal is stable again, and prepare to start the test.

[0016] Further, the specific method of the test is as follows:

[0017] 1) Step on the brake pedal and wait for 5 s, then slowly and smoothly release the brake pedal;

[0018] 2) Wait for 2 s after the pedal returns to the initial position, step on the brake pedal again, and slowly and smoothly release the brake pedal again without waiting;

[0019] 3) Repeat step 2);

[0020] 4) Steps 1), 2), and 3) form a working cycle. Adjust the waiting time after stepping on the brake pedal and after the pedal returns to the initial position in each step, and repeat 1 to 2 working cycles.

[0021] Further, during the test process, it is necessary to record the vacuum degree and the master cylinder pressure signal of the entire test process to ensure that the two signals of the vacuum degree and the master cylinder pressure signal are on the same time axis.

[0022] Further, the specific method of step three is as follows:

[0023] When stepping on the brake pedal, the vacuum degree gradually decreases. During the process of releasing the brake pedal, the vacuum degree gradually increases. Continuing to release the brake pedal, the vacuum degree will suddenly decrease. Record the lowest level of the vacuum degree and the corresponding master cylinder pressure level at this moment. The master cylinder pressure at this time is the maximum boosting pressure of the vacuum booster at a specific vacuum degree level.

[0024] Further, record the vacuum degrees and the corresponding master cylinder pressures that meet the conditions that when stepping on the brake pedal, the vacuum degree gradually decreases, during the process of releasing the brake pedal, the vacuum degree gradually increases, and continuing to release the brake pedal, the vacuum degree will suddenly decrease in step 2), and draw the boosting characteristics of the vacuum booster to predict the maximum boosting level of the booster under various vacuum degree conditions.

[0025] The beneficial effects of the present invention are as follows:

[0026] The present invention can measure the maximum boosting pressure of the vacuum booster on the whole vehicle by using the existing CAN bus signal on the vehicle without connecting additional pedal force sensors and brake pressure sensors, thereby improving the test efficiency. Description of the Drawings

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for the embodiments will be briefly introduced below. It should be understood that the following accompanying drawings only show some embodiments of the present invention, and therefore should not be regarded as a limitation of the scope. For those of ordinary skill in the art, without creative efforts, other related accompanying drawings can also be obtained based on these drawings.

[0028] Figure 1 It is a schematic flow chart of the present invention;

[0029] Figure 2 It is a schematic diagram of Step 1 in the present invention;

[0030] Figure 3 It is a schematic diagram of Step 2 in the present invention;

[0031] Figure 4 It is a schematic diagram of the test data of the present invention. Detailed implementation manners

[0032] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. In addition, it should be noted that for the sake of convenience of description, only parts related to the present invention rather than all structures are shown in the accompanying drawings.

[0033] In the present invention, unless otherwise clearly specified and defined, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through other features therebetween.

[0034] Moreover, the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature is at a higher horizontal level than the second feature.

[0035] The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature is at a lower horizontal level than the second feature.

[0036] In the description of this embodiment, the orientation or positional relationships such as "above", "below", "left" and "right" are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of description and simplifying the operations, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for distinction in description and do not have special meanings.

[0037] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0038] Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0039] Refer to Figure 1 , a vehicle test method for the maximum boost pressure of a brake vacuum booster, comprising the following steps:

[0040] Refer to Figure 2 , Step 1, test preparation;

[0041] The specific method is as follows:

[0042] Determine that the engine of the test vehicle is normal;

[0043] Determining that the engine of the test vehicle is normal includes determining that the engine of the test vehicle can start and run normally, the whole vehicle has no engine fault alarm, and there is no abnormal noise and vibration when the engine is running.

[0044] Determine that the pipeline is normal;

[0045] Determining that the pipeline is normal includes determining that the pipeline connection between the vacuum booster and the engine is normal, without blockage, air leakage, etc.

[0046] Determine that the signals of the vehicle vacuum sensor, master cylinder pressure sensor and CAN bus are normal.

[0047] The signals of the master cylinder pressure sensor and the CAN bus signal are read normally through the data acquisition device.

[0048] Step 2, test;

[0049] The specific method is as follows:

[0050] Connect the CAN bus signal acquisition device, start the engine, wait for 1 minute until the signal of the vacuum chamber vacuum sensor of the vacuum booster is stable, step on the brake pedal and then release the pedal, observe the change of the vacuum sensor signal, and start the device to record the CAN signal after the vacuum signal is stable again, and prepare to start the test.

[0051] Refer to Figure 3 , the specific method of the test is as follows:

[0052] 1) Press the brake pedal and wait for 5 s, then slowly and smoothly release the brake pedal;

[0053] 2) After the pedal returns to the initial position, wait for 2 s, then press the brake pedal again. Without waiting, slowly and smoothly release the brake pedal again;

[0054] 3) Repeat step 2);

[0055] 4) Steps 1), 2), and 3) form one working cycle. Adjust the waiting time when pressing the brake pedal and after the pedal returns to the initial position in each step, and repeat 1 to 2 working cycles.

[0056] During the test process, record the vacuum degree and the master cylinder pressure signal of the entire test process to ensure that the two signals of the vacuum degree and the master cylinder pressure signal are on the same time axis.

[0057] Step 3. Post-test processing.

[0058] The specific method is as follows:

[0059] When the brake pedal is pressed, the vacuum degree gradually decreases. During the process of releasing the brake pedal, the vacuum degree gradually increases. When the brake pedal continues to be released, the vacuum degree will suddenly decrease. Record the lowest level of the vacuum degree and the corresponding master cylinder pressure level at this moment. The master cylinder pressure at this time is the maximum boosting pressure of the vacuum booster at a specific vacuum degree level.

[0060] Record the vacuum degrees and the corresponding master cylinder pressures that meet the conditions that when the brake pedal is pressed, the vacuum degree gradually decreases, during the process of releasing the brake pedal, the vacuum degree gradually increases, and when the brake pedal continues to be released, the vacuum degree will suddenly decrease in step 2), and plot the boosting characteristics of the vacuum booster to predict the maximum boosting level of the booster under various vacuum degree conditions.

[0061] The vacuum booster uses the pressure difference between the vacuum environment and the atmospheric environment on both sides of the booster diaphragm in its cavity to generate an additional thrust to help the driver control the braking hydraulic pressure. One side of the booster diaphragm, the vacuum chamber, is connected to the engine intake manifold, and its vacuum degree is provided by the engine. The atmospheric chamber on the other side of the booster diaphragm is connected to the vacuum chamber when not braking and is separated from the external atmosphere. When braking, the atmospheric chamber is separated from the vacuum chamber, and as the driver's pedal force increases, the atmosphere gradually enters. The internal air pressure level is related to the driver's pedal force; when the atmospheric chamber is filled with the atmosphere, the pressure difference between the two sides of the booster diaphragm is the largest, and at this time, the vacuum booster generates the maximum boosting pressure.

[0062] The boosting pressure level of the vacuum booster is related to the braking pedal force level. The greater the input pedal force, the more air enters the atmosphere from the atmospheric chamber, and the greater the boosting pressure. After reaching the maximum boosting pressure, even if the pedal force is increased further, since the atmospheric chamber is already filled with air, the pressure difference across the boosting diaphragm will not increase anymore. The increase in the vacuum booster pressure will only be affected by the increase in the pedal force and will no longer be related to the air pressure in the rear chamber of the booster. Usually, to measure the maximum boosting pressure, it is necessary to collect the braking pedal force signal simultaneously and determine the maximum boosting pressure of the booster by judging the relationship between the change level of the boosting pressure and the pedal force level.

[0063] During the process of releasing the braking pedal under conditions higher than the maximum boosting pressure, before the maximum boosting pressure, the vacuum chamber and the atmospheric chamber are still isolated. The vacuum degree in the vacuum chamber will gradually increase as the pedal retracts. When approaching the maximum boosting position, if the pedal force is further reduced, the vacuum chamber will be connected to the atmospheric chamber, and the gas will flow from the atmospheric chamber of the booster to the vacuum chamber. This will significantly cause the air pressure in the vacuum chamber of the booster to increase (the vacuum degree to decrease), and at the same time, the air pressure in the vacuum chamber will have an opposite change gradient. The maximum boosting pressure is the master cylinder pressure corresponding to the conversion of the air pressure in the vacuum chamber. See Figure 4 , where the curve with large fluctuations is the hydraulic pressure of the vacuum booster, and the curve with small fluctuations is the vacuum degree of the vacuum chamber of the vacuum booster.

[0064] The present invention can measure the maximum boosting pressure of the vacuum booster on the vehicle using the existing CAN bus signal in the vehicle without connecting additional pedal force sensors and braking pressure sensors, thereby improving the test efficiency.

[0065] The preferred embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the protection scope of the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, any person skilled in the art within the technical scope disclosed by the present invention can make equivalent substitutions or changes according to the technical solution and inventive concept of the present invention. These simple variations all fall within the protection scope of the present invention.

[0066] In addition, it should be noted that, in the case of no contradiction, the various specific technical features described in the above specific embodiments can be combined in any suitable manner. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0067] Furthermore, any arbitrary combination can be made between various different embodiments of the present invention as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A vehicle test method for the maximum boost pressure of a brake vacuum booster, characterized in that, It includes the following steps: Step 1: Test preparation; Step 2: Test; Step 3: Post-test processing; The specific method of Step 2 is as follows: Connect the CAN bus signal acquisition device, start the engine, wait for 1 min until the signal of the vacuum degree sensor in the vacuum chamber of the vacuum booster is stable, step on the brake pedal and then release it, observe the change of the signal of the vacuum degree sensor, and start the device to record the CAN signal after the vacuum degree signal is stable again, and prepare to start the test; The specific method of the test is as follows: 1) Step on the brake pedal and wait for 5 s, then slowly and smoothly release the brake pedal; 2) Wait for 2 s after the pedal returns to the initial position, step on the brake pedal again, and slowly and smoothly release the brake pedal without waiting; 3) Repeat Step 2; 4) Steps 1), 2), and 3) are one working cycle. Adjust the waiting time after stepping on the brake pedal and after the pedal returns to the initial position in each step, and repeat 1 to 2 working cycles; The specific method of Step 3 is as follows: When stepping on the brake pedal, the vacuum degree gradually decreases, and when releasing the brake pedal, the vacuum degree gradually increases. Continuing to release the brake pedal, the vacuum degree will suddenly decrease. Record the lowest level of the vacuum degree and the corresponding master cylinder pressure level at this moment. The master cylinder pressure at this time is the maximum boosting pressure of the vacuum booster at a specific vacuum degree level.

2. The vehicle test method for the maximum boost pressure of a brake vacuum booster according to claim 1, characterized in that, The specific method of Step 1 is as follows: Ensure that the engine of the test vehicle is normal; ensure that the pipeline is normal; ensure that the vehicle vacuum degree sensor, master cylinder pressure sensor, and CAN bus signal are normal.

3. A vehicle test method for the maximum boost pressure of a brake vacuum booster according to claim 2, characterized in that Ensuring that the engine of the test vehicle is normal includes ensuring that the engine of the test vehicle can start and run normally, there is no engine fault alarm on the whole vehicle, and there is no abnormal noise and vibration when the engine is running.

4. A vehicle test method for the maximum boost pressure of a brake vacuum booster according to claim 2, characterized in that, Ensuring that the pipeline is normal includes ensuring that the pipeline connection between the vacuum booster and the engine is normal, without blockage or air leakage.

5. A method for testing the maximum boost pressure of a vehicle's brake vacuum booster according to claim 2, characterized in that, The signals of the master cylinder pressure sensor and the CAN bus signal are normally read through the data acquisition device.

6. A vehicle test method for the maximum boost pressure of a brake vacuum booster according to claim 1, characterized in that During the test process, it is necessary to record the vacuum degree and the master cylinder pressure signal of the whole test process to ensure that the two signals of the vacuum degree and the master cylinder pressure signal are on the same time axis.

7. A vehicle test method for the maximum boost pressure of a brake vacuum booster according to claim 1, characterized in that Record the vacuum degree and the corresponding master cylinder pressure that meet the conditions that when stepping on the brake pedal, the vacuum degree gradually decreases, when releasing the brake pedal, the vacuum degree gradually increases, and when continuing to release the brake pedal, the vacuum degree will suddenly decrease in Step 2), and draw the boosting characteristics of the vacuum booster to predict the maximum boosting level of the booster under various vacuum degree conditions.

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