Test bench method and device for simulating brake fluid state of whole vehicle continuously descending long slope

Abstract

The present application relates to a kind of bench test method and device for simulating the brake fluid state of whole vehicle continuous downhill braking;Including: test initial setting;Environment bin temperature is set to 30-50 DEG C, cooling air temperature is set to 30-50 DEG C, cooling air speed is set to 50-90 km / h;Brake disc heating;Brake disc temperature keeps;Timing to test end, brake disc temperature is always kept between 580-620 DEG C, whether brake fluid temperature exceeds brake fluid boiling point temperature in the whole process of test;The present application fully identifies whether there is user use risk after mountain continuous driving in the stage of bench test, saves the test cost of whole vehicle, avoids test personnel safety risk, simultaneously moves the development risk detection forward.

Description

Technical Field

[0001] This invention belongs to the field of automotive testing technology and relates to a bench test method and apparatus for simulating the brake fluid state of a vehicle continuously descending a long slope. Background Technology

[0002] Currently, the braking industry lacks bench testing methods to determine whether brake fluid boiling occurs after continuous driving in mountainous areas, potentially affecting user safety. The only existing methods rely on whole-vehicle testing, which involves testing brake fluid temperature and pedal feel after prolonged downhill driving to assess the rationality of the vehicle's braking system design and whether continuous use in mountainous conditions could lead to brake fluid boiling. However, whole-vehicle testing is expensive and poses potential risks to the personal safety of test drivers.

[0003] Patent document CN108167270A pertains to a method for bleeding brake hydraulic lines, specifically an automatic bleeding device and method for the hydraulic system of an electro-hydraulic brake test bench. This device includes a front brake wheel cylinder, a test bench body, a transparent hose, a rear brake wheel cylinder, a vehicle electronic stability system, a master brake cylinder, a reservoir, an electromechanical brake booster, a support, a brake pedal, an adjustable seat, a signal acquisition and transmission platform, a PC, hydraulic lines for the master brake cylinder, a two-position two-way solenoid valve, a caliper disc brake, and hydraulic lines for the brake wheel cylinders. This invention uses a camera to capture the state of brake fluid being discharged from the transparent hose, and after identification and processing, automatically determines the completion time of bleeding. The ECU of the electromechanical brake booster controls the rotation of the motor, simulating the operation of pressing and releasing the pedal. This automatic bleeding control is more precise, efficient, convenient, and thorough, solving problems such as time-consuming and laborious brake bleeding processes, incomplete bleeding, and brake fluid corrosion of operators.

[0004] The aforementioned patent discloses an exhaust device and corresponding exhaust operation method for a hydraulic system of electro-hydraulic braking, which is of little relevance to this application.

[0005] Patent document CN210153280U discloses a brake fluid filling and discharging machine circulating filling device, including a confluencer, a two-position two-way valve, a two-position three-way valve, and a valve body. The upper end of the confluencer is sealed and connected to the four reservoirs of the brake fluid filling and discharging machine through pipelines. The valve body is fixedly connected to the lower end of the confluencer. The two-position two-way valve and the two-position three-way valve are embedded inside the valve body. The two ends of the two-position two-way valve are connected to the confluencer and the two-position three-way valve, respectively. One end of the two-position three-way valve is connected to the two-position two-way valve, and the other two ends are connected to the first and second guide holes on the valve body, respectively. The first guide hole on the valve body is sealed and connected to the brake fluid storage cylinder inside the brake fluid filling and discharging machine through a pipeline, and the second guide hole is sealed and connected to the waste fluid tank through a pipeline. This utility model modifies the original brake fluid filling and discharging machine, realizes the connection between the four reservoirs of the brake fluid filling and discharging machine and the brake fluid storage cylinder, and sets two working modes through the valve system: venting of the test bench brake system and venting of the whole vehicle brake system.

[0006] The aforementioned patent discloses a method for installing brake fluid on a test bench, which is not very relevant to this application.

[0007] Patent document CN201034995Y discloses a dual-chamber, dual-circuit brake fluid performance simulation test master cylinder. The cylinder contains two sets of pistons, piston cups, and a return spring. The cylinder body has inlets and outlets corresponding to the two sets of pistons and piston cups, and a return buffer spring connects the two sets of pistons and piston cups. The key feature is that the two inlets on the cylinder body are connected to the two outlets on an inlet connector. The two outlets on the inlet connector are connected within the inlet connector and then connected to an external inlet. Similarly, the two outlets on the cylinder body are connected to the two inlets on an outlet connector. The two inlets on the outlet connector are connected within the outlet connector and then connected to an external outlet. The inlet and outlet connectors can simultaneously distribute the test fluid through a single inlet to both chambers within the cylinder body and collect the test fluid from the two outlets into a single outlet for discharge, without altering the original brake fluid performance simulation test bench structure or ensuring a constant piston stroke.

[0008] The aforementioned patent describes a brake master cylinder form that simulates the flow performance of brake fluid, which is of little relevance to this application. Summary of the Invention

[0009] This invention proposes a method and device for detecting brake fluid temperature after simulating continuous long downhill driving by a user on a test bench. The purpose is to fully identify whether the vehicle braking system design has user risks after continuous driving in mountainous areas during the test bench stage, save vehicle testing costs, avoid safety risks for test personnel, and move the detection of development risks forward.

[0010] This test method can also be applied to the selection of friction materials and to make a horizontal comparison of brake fluid temperature.

[0011] It should be noted that in this paper, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0012] Moreover, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0013] To solve the above-mentioned technical problems, the present invention is implemented using the following technical solution:

[0014] A bench test method for simulating the brake fluid condition of a vehicle continuously descending a long slope includes the following steps:

[0015] Step 1, Initial setup for the experiment;

[0016] The ambient temperature was set to 30℃-50℃, the cooling air temperature was set to 30℃-50℃, the cooling air speed was set to 50km / h-90km / h, and the test inertia was set to the full load condition of the vehicle.

[0017] The brake caliper and brake disc are clamped onto the test fixture inside the environmental chamber;

[0018] A hydraulic sensor is connected to the bleed screw of the brake caliper, and the oil inlet of the brake caliper is connected to the hydraulic system of the test bench via a hose.

[0019] When the brake disc temperature is the same as the ambient chamber temperature, begin the next test.

[0020] Step 2, brake disc heating;

[0021] ① Drive the test bench to make the brake disc rotate at V1;

[0022] ② Apply hydraulic pressure to the brake caliper through the hydraulic system of the test bench, so that the brake caliper generates a braking torque equivalent to the deceleration of the whole vehicle of 0.6g on the brake disc. When the speed of the brake disc is lower than 3km / h, stop the hydraulic input of the test bench.

[0023] ③Referring to the vehicle's actual maximum acceleration capability, increase the brake disc speed to V1 again within the corresponding time; repeat steps ①②③ above until the brake disc temperature reaches T;

[0024] Step 3: Maintain brake disc temperature;

[0025] Timing begins when the brake disc temperature first reaches T, and the brake disc speed is adjusted to V2 to maintain uniform rotation. The brake disc temperature is monitored in real time. Whenever the brake disc temperature drops below 580℃, hydraulic pressure is applied to the brake caliper through the test bench hydraulic system, causing the brake caliper to generate a braking torque equivalent to 0.3g deceleration of the entire vehicle on the brake disc. When the brake disc temperature reaches T again, the test bench hydraulic input is stopped. Throughout the above process, the brake disc speed is maintained at V2.

[0026] Step 4, the experiment ends;

[0027] Throughout the test, the brake disc temperature remained between 580-620℃. During the entire test, the brake fluid temperature was monitored to ensure it did not exceed the boiling point of the brake fluid.

[0028] Furthermore, the test bench brake fluid storage container is an insulated container with a volume adjustable in the range of 1-3L; a temperature thermocouple is provided 1mm below the brake disc friction surface.

[0029] Furthermore, the test inertia is used to simulate the load state of a whole vehicle during road testing;

[0030] The ambient temperature of the environmental chamber is adjustable to simulate the highest ambient temperature during actual use by the user.

[0031] Furthermore, the brake disc speed V1 is selected within the range of 80-120 km / h.

[0032] Furthermore, the brake disc speed V2 is selected within the range of 50-70 km / h.

[0033] Furthermore, the brake disc temperature T ranges from 600℃ to 630℃.

[0034] Furthermore, the thickness of the friction material is the maximum usable thickness indicated on the drawing plus 1 mm, simulating the lower limit of the heat capacity of the friction pad during user use;

[0035] The wheel was selected from the sample with the smallest opening area to simulate the worst heat dissipation environment among all configurations of this model.

[0036] A bench test apparatus for simulating the brake fluid state of a vehicle continuously descending a long slope includes a test bench, a hydraulic system, an environmental chamber, brake calipers, and brake discs;

[0037] The test bench is covered with an environmental chamber and is equipped with a hydraulic system.

[0038] The brake calipers and brake discs are clamped onto the test fixtures inside the environmental chamber;

[0039] A hydraulic sensor is connected to the bleed screw of the brake caliper, and the oil inlet of the brake caliper is connected to the hydraulic system of the test bench via a hose.

[0040] Furthermore, the hydraulic system is supplied with liquid from a bench brake fluid storage container;

[0041] A temperature sensor is installed inside the brake fluid storage container on the test bench.

[0042] A temperature thermocouple is installed under the friction surface of the brake disc.

[0043] Furthermore, the brake disc thickness is the maximum usable thickness indicated on the drawing, simulating the lower limit of the brake disc's heat capacity during user operation.

[0044] Compared with the prior art, the beneficial effects of the present invention are:

[0045] This invention innovatively simulates the brake fluid state under long downhill driving conditions of a vehicle on a test bench.

[0046] This invention utilizes a test bench brake fluid supply device and an adjustable-capacity sealed heat-insulating device to simulate the volume of a real vehicle's brake fluid reservoir. This avoids the temperature transfer caused by the non-sealed and large-capacity brake fluid supply device of conventional test benches, thereby avoiding the adverse consequences of distorted brake fluid temperature test results.

[0047] This invention fully identifies whether the vehicle braking system design poses a risk to user use after continuous driving in mountainous areas, saves on vehicle testing costs, avoids safety risks for test personnel, and moves the development risk detection forward. Attached Figure Description

[0048] The invention will now be further described with reference to the accompanying drawings:

[0049] Figure 1 This is a flowchart of a bench test method for simulating the brake fluid state of a vehicle continuously descending a long slope, as described in this invention.

[0050] Figure 2 This is a framework diagram of a bench test method for simulating the brake fluid state of a vehicle continuously descending a long slope, as described in this invention. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0052] The described embodiments are some, but not all, of the embodiments of the present invention. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0053] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. The embodiments of this invention will now be described in detail with reference to the accompanying drawings.

[0054] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0055] The present invention will now be described in detail with reference to the accompanying drawings:

[0056] This invention innovatively proposes a method for simulating the brake fluid state under long downhill driving conditions of a whole vehicle on a test bench.

[0057] By employing a test procedure based on the transformation of the road spectrum of a long downhill test of a whole vehicle, the risk of brake fluid boiling under continuous long downhill driving conditions was fully simulated.

[0058] See Figure 1 , Figure 2 A bench test method for simulating the brake fluid condition of a vehicle continuously descending a long slope includes:

[0059] Step 1: Experimental conditions;

[0060] An inertial test bench with an environmental chamber is used to simulate the load conditions of a whole vehicle during road testing;

[0061] The cooling fan speed setting simulates the heat dissipation and ventilation conditions during a long downhill slope.

[0062] The ambient temperature is adjustable to simulate the highest ambient temperature during actual use by the user;

[0063] The bench brake fluid supply device is a special sealed insulated container with adjustable capacity, used to simulate the actual total amount of brake fluid in the vehicle's brake lines. In order to deliberately enhance the intensity of the bench test, the container has been insulated to prevent rapid temperature exchange with the environment.

[0064] A temperature sensor is installed at the bleed screw of the brake caliper to simulate the temperature of the brake fluid in the brake actuator.

[0065] Step 2: Sample selection for the test;

[0066] The thickness of the brake disc is the maximum usable thickness indicated on the drawing, simulating the lower limit of the brake disc's heat capacity during user operation;

[0067] The thickness of the friction material is the maximum usable thickness indicated on the drawing plus 1mm, simulating the lower limit of the heat capacity of the friction pad during user use;

[0068] The wheel is selected from the sample with the smallest opening area;

[0069] Brake calipers, bearings, and steering knuckles can be made using brand new samples.

[0070] Step 3: Experimental procedure setup;

[0071] This invention employs a test procedure based on the transformation of road spectrum from a long downhill test of a whole vehicle to fully simulate the risk of brake fluid boiling under continuous long downhill driving conditions.

[0072] ① Vehicle Test Data Basis: According to statistics from the vehicle testing department and road test suppliers, a certain mountainous area in China features a continuous 20-kilometer downhill section, the longest continuous downhill mileage in the country. On this section, a road test supplier collected road profile data from multiple domestic OEMs and various vehicle models. The vehicles were fully loaded, and the drivers continuously maintained their brake pedals to ensure the vehicle speed did not exceed the requirements of this section. The test took approximately 50 minutes. During this continuous 50-minute downhill run, the highest brake disc temperature for all tested vehicles reached 600℃. To enhance the simulation of bench testing, the duration of the continuous downhill run was set to 1 hour and 15 minutes.

[0073] ② Test procedure, see [link / reference] Figure 1 :

[0074] First, initial setup of the experiment

[0075] The ambient temperature is set to (30-50)℃, the cooling air temperature is set to (30-50)℃, and the cooling air speed is set to (50-90)km / h; the ambient temperature can be adjusted to 40℃, the cooling air temperature can be adjusted to 40℃, and the air speed can be converted to 70km / h.

[0076] The brake caliper and brake disc are clamped onto the test fixture inside the environmental chamber; a hydraulic sensor is connected to the bleed screw of the brake caliper, and the brake caliper oil inlet is connected to the test bench hydraulic system via a hose; the test bench brake fluid storage container is an insulated container with a volume adjustable in the range of 1-3L and equipped with a temperature sensor; a temperature thermocouple is embedded 1mm below the friction surface of the brake disc, and the next step of the test begins when the temperature of the brake disc is the same as the temperature of the environmental chamber.

[0077] Second, brake disc heating.

[0078] This invention can change the vehicle speed and deceleration used for heating operations in the test procedure.

[0079] The brake disc warming operation procedure is as follows: ① Drive the test bench to make the brake disc speed reach V1 (V1 can be selected within the range of 80-120km / h); ② Apply hydraulic pressure to the brake caliper through the hydraulic system of the test bench to generate a braking torque equivalent to the vehicle's 0.6g deceleration on the brake disc. When the brake disc speed is lower than 3km / h, stop the hydraulic input of the test bench; ③ Referring to the actual maximum acceleration capability of the vehicle, increase the brake disc speed back to V1 within the corresponding time; Repeat the above steps ①②③ until the brake disc temperature reaches T (600℃≤T≤630℃); Alternatively, the brake disc can be warmed to 620℃ using a fixed brake warming operation. The fixed brake warming operation is: 70km / h, braking torque corresponding to 0.3g deceleration, constant torque drag braking.

[0080] Third, brake disc temperature maintenance (simulation of brake disc temperature during continuous long downhill descent).

[0081] Timing begins when the brake disc temperature first reaches T, and the brake disc speed is adjusted to V2 (V2 can be selected within the range of 50-70 km / h) and kept at a constant speed. The brake disc temperature is monitored in real time. Whenever the brake disc temperature drops below 580℃, hydraulic pressure is applied to the brake caliper through the test bench hydraulic system to generate a braking torque equivalent to the vehicle's deceleration of 0.3g. When the brake disc temperature reaches T again, the test bench hydraulic input is stopped.

[0082] 4. The experiment ends.

[0083] The test was conducted at 1 hour and 15 minutes (based on the actual driving time during a continuous long downhill driving condition in a certain region of China, for example, timed to 1 hour). The brake disc temperature remained between 580-620℃ throughout the test. The brake fluid temperature was monitored throughout the test to ensure it did not exceed the boiling point of the brake fluid.

[0084] This invention utilizes a test bench brake fluid supply device and a sealed, heat-insulating appliance with adjustable capacity to simulate the volume of a real vehicle's brake fluid reservoir. This avoids the temperature transfer caused by the non-sealed and large-capacity brake fluid supply device of conventional test benches, which leads to distorted brake fluid temperature test results.

[0085] A bench test apparatus for simulating the brake fluid state of a vehicle continuously descending a long slope includes a test bench, a hydraulic system, an environmental chamber, brake calipers, and brake discs;

[0086] The test bench is covered with an environmental chamber and is equipped with a hydraulic system.

[0087] The brake calipers and brake discs are clamped onto the test fixtures inside the environmental chamber;

[0088] A hydraulic sensor is connected to the bleed screw of the brake caliper, and the oil inlet of the brake caliper is connected to the hydraulic system of the test bench via a hose.

[0089] The test bench hydraulic system is supplied with fluid from the test bench brake fluid storage container;

[0090] A temperature sensor is installed inside the brake fluid storage container on the test bench.

[0091] A temperature thermocouple is installed under the friction surface of the brake disc.

[0092] The brake disc thickness is the maximum usable thickness indicated on the drawing, simulating the lower limit of the brake disc's heat capacity during user operation.

[0093] The above-mentioned test apparatus was used for testing:

[0094] Initial test settings: ambient temperature set at 30℃-50℃, cooling air temperature set at 30℃.

[0095] -50℃, cooling air speed set to 50km / h-90km / h; test inertia set to full vehicle load condition;

[0096] Test inertia, used to simulate the load conditions of a full vehicle during road testing;

[0097] The ambient temperature is adjustable to simulate the highest ambient temperature during actual use by the user.

[0098] The brake calipers and brake discs are clamped onto the test fixtures inside the environmental chamber;

[0099] A hydraulic sensor is connected to the bleed screw of the brake caliper, and the oil inlet of the brake caliper is connected to the hydraulic system of the test bench via a hose.

[0100] The test bench brake fluid storage container is an insulated container with an adjustable volume of 1-3L;

[0101] A temperature thermocouple is installed 1 mm below the friction surface of the brake disc.

[0102] Brake disc temperature rises;

[0103] Brake disc temperature maintained;

[0104] Throughout the test, the brake disc temperature remained between 580-620℃. During the entire test, the brake fluid temperature was monitored to ensure it did not exceed the boiling point of the brake fluid.

[0105] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be included within the scope of protection of the present invention. Furthermore, all content not described in detail in this specification is prior art known to those skilled in the art.

Claims

1. A bench test method for simulating the brake fluid condition of a vehicle continuously descending a long slope, characterized in that, Includes the following steps: Step 1, Initial setup for the experiment; The ambient temperature was set to 30℃-50℃, the cooling air temperature was set to 30℃-50℃, the cooling air speed was set to 50km / h-90km / h, and the test inertia was set to the full load condition of the vehicle. The brake caliper and brake disc are clamped onto the test fixture inside the environmental chamber; a hydraulic sensor is connected to the brake caliper bleed screw, and the brake caliper oil inlet is connected to the test bench hydraulic system via a hose. When the brake disc temperature is the same as the ambient chamber temperature, begin the next test. Step 2, brake disc heating; ① Drive the test bench to make the brake disc rotate at V1; ② Apply hydraulic pressure to the brake caliper through the hydraulic system of the test bench, so that the brake caliper generates a braking torque equivalent to the deceleration of the whole vehicle of 0.6g on the brake disc. When the speed of the brake disc is lower than 3km / h, stop the hydraulic input of the test bench. ③Referring to the vehicle's actual maximum acceleration capability, increase the brake disc speed to V1 again within the corresponding time; repeat steps ①②③ above until the brake disc temperature reaches T; Step 3: Maintain brake disc temperature; Timing begins when the brake disc temperature first reaches T, and the brake disc speed is adjusted to V2 to maintain uniform rotation. The brake disc temperature is monitored in real time. Whenever the brake disc temperature drops below 580℃, hydraulic pressure is applied to the brake caliper through the test bench hydraulic system, causing the brake caliper to generate a braking torque equivalent to 0.3g deceleration of the entire vehicle on the brake disc. When the brake disc temperature reaches T again, the test bench hydraulic input is stopped. Throughout the above process, the brake disc speed is maintained at V2. Step 4, the experiment ends; Throughout the test, the brake disc temperature remained between 580-620℃. During the entire test, the brake fluid temperature was monitored to ensure it did not exceed the boiling point of the brake fluid.

2. The bench test method for simulating the brake fluid state of a vehicle continuously descending a long slope according to claim 1, characterized in that: The test bench brake fluid storage container is an insulated container with an adjustable volume of 1-3L; a temperature thermocouple is installed 1mm below the brake disc friction surface.

3. The bench test method for simulating the brake fluid state of a vehicle continuously descending a long slope according to claim 1, characterized in that: The test inertia is used to simulate the load state of the whole vehicle during road testing; The ambient temperature of the environmental chamber is adjustable to simulate the highest ambient temperature during actual use by the user.

4. The bench test method for simulating the brake fluid state of a vehicle continuously descending a long slope according to claim 1, characterized in that: The brake disc speed V1 is selected within the range of 80-120 km / h.

5. The bench test method for simulating the brake fluid state of a vehicle continuously descending a long slope according to claim 1, characterized in that: The brake disc speed V2 is selected within the range of 50-70 km / h.

6. The bench test method for simulating the brake fluid state of a vehicle continuously descending a long slope according to claim 1, characterized in that: The brake disc temperature T ranges from 600℃ to 630℃.

7. The bench test method for simulating the brake fluid state of a vehicle continuously descending a long slope according to claim 1, characterized in that: The thickness of the friction material is the maximum usable thickness indicated on the drawing plus 1mm, simulating the lower limit of the heat capacity of the friction pad during user use; The wheel was selected from the sample with the smallest opening area to simulate the worst heat dissipation environment among all configurations of the vehicle.

8. The test apparatus for a bench test method simulating the brake fluid state of a vehicle continuously descending a long slope as described in claim 1, characterized in that: Includes test bench, hydraulic system, environmental chamber, brake caliper, and brake disc; The test bench is covered with an environmental chamber and is equipped with a hydraulic system. The brake calipers and brake discs are clamped onto the test fixtures inside the environmental chamber; A hydraulic sensor is connected to the bleed screw of the brake caliper, and the oil inlet of the brake caliper is connected to the hydraulic system of the test bench via a hose.

9. The testing apparatus according to claim 8, characterized in that: The hydraulic system is supplied with fluid from a bench brake fluid storage container; A temperature sensor is installed inside the brake fluid storage container on the test bench. A temperature thermocouple is installed under the friction surface of the brake disc.

10. The testing apparatus according to claim 9, characterized in that: The brake disc thickness is the maximum usable thickness indicated on the drawing, simulating the lower limit of the brake disc's heat capacity during user operation.

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