Thermal balance test method for automobile retarder

Abstract

The invention discloses a thermal balance test method for an automobile retarder, which mainly utilizes a drum test bench provided with an environment bin to formulate a thermal balance test process for the automobile retarder, can accurately and efficiently test the thermal balance of the automobile retarder, and provides reliable data support for research, development and improvement of the retarder. The method specifically comprises the following steps of: pre-deploying temperature sensing devices such as an environment and retarder cooling liquid, and setting a test boundary condition; after a test environment, equipment and a vehicle are prepared based on a test boundary condition, a slope road spectrum is utilized to carry out a continuous long slope descending working condition test and a limit downhill working condition test. According to the invention, the test is carried out based on the actual vehicle use scene and the technical standard in the industry, and the test focus is focused on the heat dissipation capability of the retarder in the long-time and large-load use scene in combination with the road spectrum capable of covering various ramp working conditions, so that the auxiliary braking performance and the service life of the retarder can be effectively guaranteed through the test scheme, and the test efficiency is improved. Therefore, the safety of drivers and passengers is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of automobile testing technology, and in particular to a method for testing thermal equilibrium of an automobile retarder. BACKGROUND

[0002] An automobile retarder plays a key role in the braking process of a vehicle, especially when driving down a long downhill slope, the frequency of using the retarder is very high. During the working process of the automobile retarder, a large amount of heat is generated, causing the temperature of the retarder to rise. If the heat cannot be dissipated in time, not only will the braking efficiency of the retarder be reduced, but in severe cases, brake failure may occur, endangering driving safety.

[0003] The existing test method only tests the maximum braking performance of the retarder, the test distance is short, and the scene of driving down a long downhill slope cannot be simulated. Moreover, the retarder has different braking gears and constant speed braking gears, and the existing method cannot comprehensively test the thermal equilibrium of the automobile retarder, and cannot meet the needs of in-depth research and optimization of the performance of the retarder in the automobile industry.

[0004] To be specific, the current vehicle braking test specification of domestic vehicle manufacturers mainly comes from GB 12676-2014 "Technical Requirements and Test Methods for Braking Systems of Commercial Vehicles and Trailers", which mentions testing using a retarder in 5.1.6 Type II working conditions, with the following requirements:

[0005] ① The braking performance should be tested under full load conditions.

[0006] ② Ensure that the full load vehicle drives down a 6% slope at an average speed of 30 km / h for 6 km.

[0007] ③ For vehicles whose energy is only absorbed by engine braking, the average speed is allowed to deviate by ±5 km / h, and the transmission gear should ensure that the vehicle drives down a 6% slope at a stable speed close to 30 km / h.

[0008] However, when designing the existing test method according to the above standard, at least the following defects are found:

[0009] (1) The retarder is used to assist in the vehicle braking test, and the braking performance test of the retarder is not carried out independently, and the heat balance capability of the retarder heat dissipation system is not concerned.

[0010] (2) The test working condition is single, and the working condition (driving down a 6% slope at an average speed of 30 km / h for 6 km) cannot fully represent the downhill working condition, and the scene of driving down a long downhill slope at high speed is not considered. SUMMARY

[0011] In view of the above, the present application aims to provide a method for testing the thermal equilibrium of an automobile retarder to solve the aforementioned technical problems.

[0012] The technical solutions adopted by the present application are as follows:

[0013] The present application provides a kind of automobile retarder thermal equilibrium test method, wherein includes:

[0014] Pre-configure several temperature sensors on the vehicle to be measured, at least including ambient temperature sensor and retarder coolant temperature sensor;

[0015] According to the set test boundary condition, trigger environment warehouse and drum test bench readiness;

[0016] Using pre-constructed slope road spectrum, carry out continuous long downhill working condition test and limit downhill working condition test, wherein the slope road spectrum includes a plurality of slope setting values based on actual mountainous road configuration;And, test process includes: using the temperature feedback of retarder coolant to preheat;Set different slope values and target speed values for testing until the temperature of retarder coolant reaches the given equilibrium state.

[0017] In at least one possible implementation, the continuous long downhill working condition includes:

[0018] According to the given speed trigger vehicle to be measured to run, preheat retarder coolant;

[0019] After preheating, start retarder, and set retarder gear to the given constant speed gear;

[0020] According to no more than the first target speed and the first slope value, simulate continuous downhill driving until the temperature of retarder coolant reaches the equilibrium state, then close the retarder;

[0021] According to the given speed and 0 slope value, drive until the temperature of retarder coolant reaches the equilibrium state, then start the retarder again and set the retarder gear to the constant speed gear;

[0022] According to no more than the second target and the second slope value, simulate continuous downhill driving until the temperature of retarder coolant reaches the equilibrium state, then close the retarder.

[0023] In at least one possible implementation, the limit downhill working condition test includes:

[0024] According to the given speed trigger vehicle to be measured to run, preheat retarder coolant;

[0025] After preheating, start retarder, and set retarder gear to the given maximum gear;

[0026] simulate the limit downhill driving according to the third target vehicle speed and the third slope value until the temperature of the retarder coolant reaches a balanced state, and the retarder is closed; and

[0027] During the test, if it is detected that the actual vehicle speed increases by more than the first threshold value, the vehicle speed is reduced to not more than the third target vehicle speed by braking; and if it is detected that the actual vehicle speed decreases by more than the second threshold value, the retarder gear position is lowered by one gear and the test is continued.

[0028] In at least one possible implementation, the test method further comprises:

[0029] According to the predetermined engine speed limit value and the target vehicle speed value, the gear position of the gearbox is calculated;

[0030] The calculation result of the gear position of the gearbox is taken as the highest gear position corresponding to the engine speed limit value and the target vehicle speed value under the current test condition;

[0031] The highest gear position is taken as one of the initial test parameters for each test condition, and after the retarder is started, it is detected whether the engine speed is maintained at the engine speed limit value;

[0032] If not, the gear position of the gearbox is recalculated to adjust the test parameters under the corresponding test condition.

[0033] In at least one possible implementation, the test boundary conditions include the maximum temperature value of the environmental chamber and the maximum loading parameter of the drum test bench.

[0034] In at least one possible implementation, the test boundary conditions further include setting the vehicle-mounted air conditioner to start the external circulation, adjust to the lowest refrigeration temperature, and turn on the maximum air volume.

[0035] Compared with the prior art, the main design concept of the present application is to use a drum test bench configured with an environmental chamber to develop a test procedure for the thermal equilibrium of a vehicle retarder, which can accurately and efficiently test the thermal equilibrium of the vehicle retarder and provide reliable data support for the research and development and improvement of the retarder. Specifically, sensor devices for detecting the temperature of the test environment and the retarder coolant are deployed in advance, and test boundary conditions are set; after the test environment, equipment, and vehicle are prepared based on the test boundary conditions, continuous long downhill test conditions and limit downhill test conditions are carried out using a slope road spectrum. The present application carries out tests based on actual driving scenarios and industry technical standards, and focuses on the heat dissipation capacity of the retarder in long-time and high-load use scenarios by combining the pre-constructed road spectrum covering various slope conditions, which can effectively guarantee the auxiliary braking performance and service life of the retarder, and thus guarantee the safety of the driver and passengers. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to make the objects, technical solutions and advantages of the present application clearer, the following further describes the present application with reference to the accompanying drawings, in which:

[0037] Figure 1 A schematic diagram of the automobile retarder thermal equilibrium test method provided by the embodiment of the present application. DETAILED DESCRIPTION

[0038] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, in which the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be interpreted as a limitation on the present application.

[0039] The present application proposes an embodiment of an automobile retarder thermal equilibrium test method, specifically as shown in Figure 1 , which includes:

[0040] Step S1, a plurality of temperature sensors are configured in advance on the vehicle to be tested, including at least an ambient temperature sensor and a retarder coolant (retarder inlet and outlet water) temperature sensor;

[0041] In addition to the above-mentioned sensors, temperature sensors can also be deployed at specific parts such as radiator inlet and outlet water, windward, fan, etc. and connected with the data acquisition system and the upper computer via wiring harness. In actual operation, it also includes checking the transmission state of each temperature sensor signal and CAN bus signal in advance to ensure normal testing.

[0042] Step S2, according to the set test boundary conditions, trigger the environment chamber and the drum test bench to be ready;

[0043] In actual operation, it includes heating the environment chamber according to the predetermined ambient temperature, such as 35℃, and setting the drum test bench to load according to the full load working condition of the vehicle. In addition, this step can also include preparing the state of the vehicle to be tested, which mainly includes setting the vehicle-mounted air conditioner to: start the external circulation, adjust to the lowest refrigeration temperature, and turn on the maximum air volume.

[0044] Step S3, using the pre-constructed slope road spectrum, continuous long downhill working condition test and extreme downhill working condition test are carried out, wherein the slope road spectrum includes a plurality of slope setting values based on the actual mountain road configuration; and the test process includes: using the temperature feedback of the retarder coolant for preheating; setting different slope values and target speed values for testing until the temperature of the retarder coolant reaches the predetermined equilibrium state.

[0045] Therefore, for the specific test links of the above two working conditions, for example:

[0046] First, continuous long downhill working condition:

[0047] ① The vehicle is preheated at 80±2km / h to the steady state of the retarder coolant temperature;

[0048] ② The retarder is opened, the retarder gear is located in the constant speed gear, and the vehicle is continuously driven downhill on a 3% slope at a speed not higher than 70±2km / h until the retarder coolant reaches the equilibrium state, and the retarder is closed;

[0049] ③ The slope is adjusted to 0%, and the vehicle is driven at 80±2km / h until the retarder coolant temperature stabilizes;

[0050] ④ The retarder is opened, the retarder gear is located in the constant speed gear, and the vehicle is continuously driven downhill on a 5% slope at a speed not higher than 40±2km / h until the retarder coolant reaches the equilibrium state, and the retarder is closed.

[0051] For the continuous long downhill working condition test, it is also necessary to supplement that the gearbox should not be placed in the neutral position, and the clutch pedal should not be depressed.

[0052] Second, extreme downhill working condition:

[0053] ① The vehicle is preheated at 80±2km / h to the steady state of the retarder coolant temperature;

[0054] ② The retarder is opened, the retarder gear is sequentially increased to the maximum gear (cannot be directly placed in the maximum gear), and the vehicle is continuously driven downhill on a 7% slope at a speed not higher than 30±2km / h, until the retarder coolant reaches the equilibrium state, and the retarder is closed.

[0055] For the extreme downhill working condition test, it is also necessary to supplement that if the vehicle speed increases by more than 5km / h, the brake pedal can be depressed to stabilize the vehicle speed at the test speed; if the vehicle speed decreases by more than 5km / h, the retarder gear is lowered by one gear for testing.

[0056] Finally, it can be pointed out that for the above two working conditions, first, after opening the retarder, the engine speed is preferably investigated to see if it remains at a predetermined engine speed limit, such as 1500±50r / min; second, further, according to the engine speed limit and the target vehicle speed value, the gearbox gear is calculated; the gearbox gear calculation result is used as the highest gear corresponding to the engine speed limit and the target vehicle speed value in the current test working condition,

[0057] The gearbox gear calculation formula involved here is as follows:

[0058] i o =2πr×3.6×n / V×i g

[0059] In the formula, i o : transmission gear ratio; n: engine speed (unit: r / min); r: tire rolling radius (unit: m); i g : main reducer speed ratio; V: vehicle speed (unit: km / h).

[0060] That is, under the constraint of the highest value of the transmission gear, it is continuously detected whether the engine speed meets the requirements during the test, and if not, the transmission gear can be recalculated to adjust the test parameters under the corresponding test condition.

[0061] To sum up, the main design concept of the application is to use a drum test bench equipped with an environmental chamber to develop a heat balance test process for automobile retarders, which can accurately and efficiently test the heat balance of automobile retarders and provide reliable data support for the research and development and improvement of retarders. Specifically, sensor devices for detecting the temperature of the test environment and the retarder coolant are deployed in advance, and test boundary conditions are set; after the test environment, equipment and vehicle are prepared based on the test boundary conditions, continuous long downhill working condition tests and extreme downhill working condition tests are carried out using a slope road spectrum. The application carries out tests based on actual driving scenarios and industry technical standards, and focuses on the heat dissipation capacity of the retarder in long-time and high-load use scenarios by combining the pre-constructed road spectrum that can cover various slope working conditions. The test scheme can effectively guarantee the auxiliary braking performance and service life of the retarder, and thus guarantee the safety of the driver and passengers.

[0062] In the embodiments of the application, if the expression of the position is mentioned, it is based on the relative concept of the embodiments, and in addition, "at least one" means one or more, and "multiple" means two or more. The "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the cases of A alone, A and B together, and B alone. Wherein A and B can be singular or plural. The character " / " generally represents that the front and rear associated objects are in an "or" relationship. "At least one of the following" and the like means any combination of these items, including any combination of single or multiple items. For example, at least one of a, b and c can represent: a, b, c, a and b, a and c, b and c, or a and b and c, wherein a, b and c can be single or multiple.

[0063] The above detailed description of the embodiments shown in the drawings illustrates the structure, features and effects of the present application, but the above is only a preferred embodiment of the present application, and it should be noted that the technical features involved in the above embodiments and preferred modes can be reasonably combined and matched into various equivalent schemes by those skilled in the art without departing from or changing the design idea and technical effects of the present application; therefore, the present application is not limited to the implementation range shown in the drawings, and any changes or modifications made in accordance with the concept of the present application, or equivalent embodiments with equivalent changes, shall be within the scope of protection of the present application.

Claims

1. A method of testing thermal equilibrium of an automotive retarder, characterized by, The application relates to a test method for a vehicle retarder, and belongs to the technical field of vehicle testing. The application comprises the following steps: A plurality of temperature sensors are arranged on a vehicle to be tested in advance, including at least an ambient temperature sensor and a retarder coolant temperature sensor; According to a set test boundary condition, an ambient chamber and a drum test bench are triggered to be ready; A pre-constructed slope road spectrum is used to carry out continuous long-slope working condition tests and limit down-slope working condition tests, wherein the slope road spectrum comprises a plurality of slope setting values based on actual mountain road configurations; Moreover, the test process comprises the following steps: preheating is carried out by using the temperature feedback of the retarder coolant; 2. The automotive retarder heat balance test method according to claim 1, characterized in that, Different slope values and target vehicle speed values are set for tests until the temperature of the retarder coolant reaches a given equilibrium state. The continuous long-slope working condition comprises the following steps: The vehicle to be tested is triggered to run at a given vehicle speed, and the retarder coolant is preheated; After preheating is completed, the retarder is started, and the retarder gear is set to a given constant speed gear; Continuous downhill driving is simulated at a first target vehicle speed and a first slope value, and the retarder is stopped after the temperature of the retarder coolant reaches an equilibrium state; The vehicle is driven at a given vehicle speed and a 0 slope value until the temperature of the retarder coolant reaches an equilibrium state, then the retarder is started again and the retarder gear is set to the constant speed gear; 3. The automotive retarder heat balance test method of claim 1, wherein, Continuous downhill driving is simulated at a second target vehicle speed and a second slope value, and the retarder is stopped after the temperature of the retarder coolant reaches an equilibrium state. The limit down-slope working condition test comprises the following steps: The vehicle to be tested is triggered to run at a given vehicle speed, and the retarder coolant is preheated; After preheating is completed, the retarder is started, and the retarder gear is set to a given maximum gear; Limit downhill driving is simulated at a third target vehicle speed and a third slope value, and the retarder is stopped after the temperature of the retarder coolant reaches an equilibrium state; and 4. The automotive retarder heat balance test method of claim 1, wherein, During the test, if the actual vehicle speed is detected to increase by more than a first threshold value, the vehicle speed is reduced to not more than the third target vehicle speed by braking; and if the actual vehicle speed is detected to decrease by more than a second threshold value, the retarder gear is lowered by one gear and the test is continued. The test method further comprises the following steps: According to a given engine speed limit value and the target vehicle speed value, the gear of a gearbox is calculated; The calculation result of the gear of the gearbox is used as the highest gear corresponding to the engine speed limit value and the target vehicle speed value under the current test working condition; The highest gear is used as one of the initial test parameters for each working condition test, and after the retarder is started, whether the engine speed is kept at the engine speed limit value is detected; 5. The automotive retarder heat balance test method according to any one of claims 1 to 4, characterized in that, If not, the gear of the gearbox is recalculated to adjust the test parameters under the corresponding test working condition.

6. The automotive retarder heat balance test method according to claim 5, characterized in that, The test boundary condition comprises a maximum temperature value of the ambient chamber and a maximum loading parameter of the drum test bench. The test boundary condition further comprises setting a vehicle-mounted air conditioner to start external circulation, to the lowest refrigeration temperature and to the maximum air volume.

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