A design method for loading box used in tractor test

Abstract

The invention relates to the technical field of vehicle testing, and discloses a design method for a loading compartment for a tractor test, wherein the strain-force relationship of a leaf spring guide arm, a lateral thrust rod and a leaf spring is calibrated; the calibrated parts are loaded on a vehicle, and then the suspension load spectrum is measured during a loading test of the tractor with a hook; a whole vehicle dynamic simulation model of the tractor is established; the state of the tractor with a hook is simulated, and the model is corrected according to the measured force result; the trailer of the model is removed and the loading compartment is modeled, and the length, width and height of the loading compartment are used as variables, and the judgment conditions for the convergence of the loading compartment parameter optimization are set, and the optimization is performed until the loading compartment converges, and the length, width and height of the optimized loading compartment are extracted and the density of the loading compartment is recorded, so as to design the loading compartment; the invention can realize the equivalent design of the loading compartment, effectively improve the credibility of the reliability test of the tractor back compartment loading at the saddle, and avoid abnormal damage to chassis parts due to the inequivalence between the tractor back compartment loading test and the tractor with a hook loading test.

Description

Technical Field

[0001] The invention relates to the technical field of vehicle testing, and in particular to a design method for a loading compartment for a tractor test. Background Art

[0002] Vehicle reliability test is an important method to test vehicle quality. The road surfaces for general tractor reliability test include: test field reinforced roads, mountain roads, and highways. At present, many domestic automobile manufacturers use the method of loading the trunk at the saddle instead of loading the trailer when conducting tractor reliability tests on test field reinforced roads. The main reasons are as follows:

[0003] (1) When testing on reinforced roads at a test site, there are limitations on the site, such as insufficient turning radius and difficulty in turning due to the length of the tractor and trailer. Therefore, some domestic test sites recommend testing with a tractor in the back compartment.

[0004] (2) Testing a tractor with a trailer requires high driving skills from the driver;

[0005] (3) The trailer of the tractor often fails during reliability tests, which leads to longer test time and increased test costs.

[0006] However, the current method of loading the load box at the saddle for testing mainly has the following problems:

[0007] There are great differences in the test results of the two methods of loading with a loading box and loading with a trailer in the reliability test of vehicles, especially the chassis load-bearing parts. Some parts that have been verified to be problem-free many times in the loading test with a trailer have multiple failure problems when tested with a loading box. The main reason is that the loading process generally only considers mass equivalence, that is, ensuring that the loaded mass is basically consistent with the saddle mass of the trailer on the tractor saddle, but does not consider the equivalence of torque and lateral force, and the design of the loading box is rather arbitrary. Summary of the invention

[0008] The object of the present invention is to provide a design method for a loading box for a tractor test, which can realize the equivalent design of the loading box, effectively and significantly improve the credibility of the reliability test of the tractor's trunk loading at the saddle, and at the same time avoid abnormal damage to chassis parts caused by the inequivalence of the tractor trunk loading test and the tractor belt loading test.

[0009] To achieve the above object, the present invention provides a method for designing a loading compartment for a tractor test, which comprises the following steps:

[0010] Step 1: Arrange strain gauges on the leaf spring guide arm, the lateral thrust rod and the leaf spring, and calibrate the strain-force relationship of the leaf spring guide arm, the lateral thrust rod and the leaf spring respectively;

[0011] Step 2: Install the leaf spring guide arm, lateral thrust rod and leaf spring calibrated in step 1 onto the tractor to be tested, and measure the suspension load spectrum of the tractor to be tested during the load test with a hook;

[0012] Step 3, establishing a tractor vehicle dynamics simulation model in the dynamics simulation software;

[0013] Step 4, simulating the state of the tractor with a trailer, and correcting the dynamic simulation model of the tractor according to the actual measured force result of the suspension in step 2;

[0014] Step 5, remove the trailer in the vehicle power simulation model in step 4, digitally model the loading compartment, set the loading compartment on the saddle of the vehicle power simulation model, set the density of the loading compartment, take the length, width and height of the loading compartment as variables, and assign initial values;

[0015] Step 6: Set the convergence judgment conditions for the loading compartment parameter optimization and optimize the length, width and height of the loading compartment:

[0016] Determine whether the loading compartment has converged. If so, proceed to step seven. If not, adjust the length, width, and height of the loading compartment, and re-determine whether the loading compartment has converged until the loading compartment has converged and then proceed to step seven.

[0017] Step 7, extract the length, width, and height data of the optimized loading compartment, and record the set density of the loading compartment;

[0018] Step eight, designing the loading compartment according to the length, width and height of the loading compartment optimized in step seven.

[0019] As a preferred solution of the present invention, in step 1, a strain gauge is arranged on the leaf spring guide arm; the leaf spring guide arm is rotated 90° according to the actual assembly angle position and then fixed on the tooling, a load is applied to the leaf spring guide arm shaft pin, and strain data of the leaf spring guide arm is collected at the same time, so as to obtain the relationship between the suspension X-direction load and strain;

[0020] A strain gauge is arranged on the transverse thrust rod; one end of the transverse thrust rod is fixed to the fixed end, a load is applied to the other end of the transverse thrust rod, and strain data of the transverse thrust rod is collected at the same time to obtain the relationship between the Y-direction load and strain of the suspension;

[0021] A strain gauge is set on the leaf spring, and the air suspension with the leaf spring equipped with the strain gauge is loaded on a tractor. By loading different masses on the trailer towed by the tractor and collecting the strain data of the leaf spring, the relationship between the leaf spring strain and the axle load is obtained, thereby obtaining the relationship between the suspension Z-direction load and strain.

[0022] As a preferred solution of the present invention, the strain gauge on the leaf spring guide arm is arranged at the edge of the leaf spring guide arm along the length direction of the leaf spring guide arm; the strain gauge on the transverse thrust rod is arranged along the length direction of the transverse thrust rod; the strain gauge on the leaf spring is set on the side of the leaf spring close to the axle and arranged along the length direction of the leaf spring.

[0023] As a preferred solution of the present invention, in step 6, the convergence judgment conditions include:

[0024] (1) The primary judgment condition: the deviation between the static axle load Mj of the vehicle model and the actual axle load Mc with the trailer is less than 5%;

[0025] (2) Secondary judgment conditions: the deviation between the fatigue damage value of the lateral thrust rod and the fatigue damage value obtained by actual test is less than 10%, the deviation between the fatigue damage value of the leaf spring and the fatigue damage value obtained by actual test is less than 10%, and the deviation between the fatigue damage value of the leaf spring guide arm and the fatigue damage value obtained by actual test is less than 30%.

[0026] As a preferred solution of the present invention, in step five, the density of the loading chamber is set to the density of stone or the density of iron.

[0027] As a preferred solution of the present invention, when the tractor to be tested has a total of 6 wheels and 4 of them are driving wheels, in step 5, the total mass of the loading compartment is set to 18 tons.

[0028] As a preferred solution of the present invention, in step 2, when collecting the load spectrum, the tractor with trailer to be tested collects typical road load spectrum data at a test site at a specified speed, and the typical road surfaces include twisted roads, washboard roads and Belgian roads.

[0029] Compared with the prior art, the design method of a loading compartment for a tractor test in an embodiment of the present invention has the following beneficial effects:

[0030] The present invention determines the force test scheme and calibration method of the suspension according to the force transmission characteristics of the suspension, ensures the accuracy of the test data, and only needs to perform the force test on the suspension system, without the need for special test equipment such as a six-component force test device, which can greatly reduce the test cost and time; and through the optimization design of the loading box, it is ensured that the forces acting on the saddle by the loading box and the trailer are basically equivalent, which effectively and greatly improves the credibility of the reliability test of the tractor's trunk loading at the saddle, and at the same time avoids abnormal damage to chassis components caused by the inequivalence of the tractor's trunk loading test and the tractor's trailer loading test. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the drawings of the embodiment are briefly introduced below.

[0032] Figure 1is a schematic diagram of a tractor trunk test provided by the present invention;

[0033] Figure 2 It is a structural diagram of the suspension;

[0034] In the figure, 1 is a loading compartment; 2 is a tractor frame; 3 is an axle; 4 is a suspension; 41 is a lateral thrust rod; 42 is a leaf spring guide arm; 43 is a leaf spring; and 44 is an airbag. DETAILED DESCRIPTION

[0035] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0036] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "top", "bottom", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, 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 cannot be understood as a limitation of the present invention. It should be understood that the terms "first", "second", etc. are used in the present invention to describe various information, but such information should not be limited to these terms, which are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, the "first" information may also be referred to as the "second" information, and similarly, the "second" information may also be referred to as the "first" information.

[0037] like Figure 1 to Figure 2 As shown, a design method for a loading compartment for a tractor test in a preferred embodiment of the present invention comprises the following steps:

[0038] Step 1: Arrange strain gauges on the leaf spring guide arm, the lateral thrust rod and the leaf spring, and calibrate the strain-force relationship of the leaf spring guide arm, the lateral thrust rod and the leaf spring respectively;

[0039] Step 2: Install the leaf spring guide arm, lateral thrust rod and leaf spring calibrated in step 1 onto the tractor to be tested, and measure the suspension X, Y and Z load spectra of the tractor to be tested during the load test with a hook;

[0040] Step 3: Establish a whole vehicle dynamic simulation model of the tractor in the dynamic simulation software (the whole vehicle includes the tractor main vehicle and the trailer); wherein the parameters of the whole vehicle dynamic simulation model should be as close as possible to the whole vehicle to be tested in step 2 of the test; the dynamic simulation software is preferably ADAMS software;

[0041] Step 4, simulating the state of the tractor with a trailer, and correcting the dynamic simulation model of the tractor according to the actual measured force result of the suspension in step 2;

[0042] Step 5, remove the trailer in the vehicle power simulation model in step 4, digitally model the loading compartment, set the loading compartment on the saddle of the vehicle power simulation model, set the density of the loading compartment, take the length, width and height of the loading compartment as variables, and assign initial values;

[0043] Step 6: Set the convergence judgment conditions for the loading compartment parameter optimization and optimize the length, width and height of the loading compartment:

[0044] Determine whether the loading compartment has converged. If so, proceed to step seven. If not, adjust the length, width, and height of the loading compartment, and re-determine whether the loading compartment has converged until the loading compartment has converged and then proceed to step seven.

[0045] Step 7, extract the length, width, and height data of the optimized loading compartment, and record the set density of the loading compartment;

[0046] Step 8: Design the loading compartment according to the length, width and height of the loading compartment optimized in step 7. Use the optimized loading compartment to conduct subsequent reliability test of the tractor vehicle to improve the credibility of the reliability test of the tractor loading the back compartment at the saddle (i.e., replacing the trailer loading).

[0047] It should be noted that the airbag 44 in the suspension can only transmit Z-direction load due to its own characteristics, and cannot transmit X-direction load and Y-direction load. Therefore, the leaf spring 43 and the airbag 44 mainly transmit Z-direction force, the lateral thrust rod 41 transmits Y-direction force, and the leaf spring guide arm 42 transmits X-direction force. Through the leaf spring guide arm 42, the lateral thrust rod 41 and the leaf spring 43, the three-direction forces of the suspension can be measured, thereby obtaining the suspension transmission force.

[0048] Exemplarily, in step one, a strain gauge is set on the leaf spring guide arm; the leaf spring guide arm is rotated 90° according to the actual assembly angle position (i.e., the actual assembly angle position of the leaf spring guide arm on the suspension) and then fixed on the tooling (a fixed structure for fixing the leaf spring guide arm), a load is applied to the leaf spring guide arm shaft pin, and strain data of the leaf spring guide arm is collected at the same time, so as to obtain the relationship between the X-axis load and strain of the suspension. The leaf spring guide arm is rotated 90° according to the actual assembly, so that the load can be better applied to the leaf spring guide arm, ensuring the accuracy of the measurement data; a strain gauge is set on the transverse thrust rod; one end of the transverse thrust rod is fixed At the fixed end, a load is applied to the other end of the lateral thrust rod, and the strain data of the lateral thrust rod is collected at the same time to obtain the relationship between the Y-direction load and strain of the suspension; a strain gauge is set on the leaf spring, and the air suspension with the leaf spring equipped with the strain gauge is loaded on the tractor. By loading different masses on the trailer towed by the tractor and collecting the strain data of the leaf spring at the same time, the relationship between the leaf spring strain and the axle load is obtained, thereby obtaining the relationship between the Z-direction load and strain of the suspension; since the torque influence of the loading box is transmitted to the suspension and ultimately manifested as different forces on the left and right force transmission parts of the suspension, the above test method has taken into account the influence of the loading box torque on the suspension.

[0049] Exemplarily, the strain gauge on the leaf spring guide arm is arranged at the edge of the leaf spring guide arm along the length direction of the leaf spring guide arm; the strain gauge on the transverse thrust rod is arranged along the length direction of the transverse thrust rod; the strain gauge on the leaf spring is set on the side of the leaf spring close to the axle and arranged along the length direction of the leaf spring.

[0050] Exemplarily, in step 6, the convergence judgment conditions include:

[0051] (1) Primary judgment condition: The deviation between the static axle load Mj of the vehicle model (the vehicle model is the tractor model with a loading compartment model) and the actual axle load Mc of the tractor with a trailer is less than 5%. The static error (deviation) is the basis and should be the primary judgment condition.

[0052] (2) Secondary judgment conditions: The lateral thrust rod is used as a force transmission component in the Y direction. The deviation between the fatigue damage value of the lateral thrust rod model and the fatigue damage value obtained by the actual test of the lateral thrust rod (i.e., the actual test of the tractor with a trailer) is less than 10%; the leaf spring is used as a force transmission component in the Z direction. The deviation between the fatigue damage value of the leaf spring model and the fatigue damage value obtained by the actual test of the leaf spring (i.e., the actual test of the tractor with a trailer) is less than 10%; the leaf spring guide arm is used as a force transmission component in the X direction. The deviation between the fatigue damage value of the leaf spring guide arm model and the fatigue damage value obtained by the actual test of the leaf spring guide arm (i.e., the actual test of the tractor with a trailer) is less than 30%; since the tractor-backed loading box does not have the traction force of the trailer on the tractor, and this traction force cannot be compensated by the design of the loading box, the convergence judgment condition in the X direction should be more relaxed, that is, the deviation between the fatigue damage value of the leaf spring guide arm and the fatigue damage value obtained by the actual test is larger, and the fatigue damage value of the leaf spring guide arm will be smaller than the fatigue damage value obtained by the actual test; therefore, the Z-direction and Y-direction forces are mainly considered.

[0053] When judging whether the loading compartment has converged, judge in turn whether the primary judgment condition and the secondary judgment condition are met. When both the primary judgment condition and the secondary judgment condition are met, the loading compartment converges and step seven is performed; when the primary judgment condition is not met, the loading compartment does not converge, and the length, width and height of the loading compartment are directly adjusted to continue optimization (that is, first judge whether the primary judgment condition is met and then judge whether the secondary judgment condition is met).

[0054] Exemplarily, in step five, the density of the loading compartment is set to the density of stone or iron. Since the weight block used in the test is stone or iron, the density of the loading compartment in the dynamic simulation software should be set according to the density of iron or stone, and it is necessary to record which specific density is used, so that the loading weight block is consistent with the design in the subsequent actual test, that is, if the simulation model uses iron, then iron is also used for loading in the actual test. The density of iron is usually 7.8 tons / cubic meter, and the density of cement stone is relatively large, which can be measured according to actual conditions, generally 1.25-1.6 tons / cubic meter. In the optimized design, the total mass of the loading compartment should remain unchanged, and only the size of the loading compartment should be changed. Since the force exerted by the loading compartment on the tractor should be as consistent as possible with the force exerted by the trailer, the center of gravity of the loading compartment must be at the saddle to ensure that the front and rear axle loads are basically consistent with those with the trailer.

[0055] For example, when the tractor to be tested has a total of 6 wheels and 4 of them are driving wheels, in step 5, the total mass of the loading compartment is set to 18 tons. According to national requirements, the total weight of a 6X4 tractor (i.e., a tractor with a total of 6 wheels and 4 of them are driving wheels) with a trailer is limited to 49 tons after loading. The mass of the tractor with a trailer is usually 17 tons. When the weight limit is set at 49 tons, the load applied by the trailer to the saddle of the tractor is generally 18 tons. Since the loading compartment acts directly on the saddle, it only needs to load 18 tons to be equivalent to the effect produced by loading 32 tons of mass with the trailer, which can greatly reduce the loading of the test load and reduce the test cost and time.

[0056] Exemplarily, in step 2, when collecting the load spectrum, the tractor with trailer to be tested collects typical road load spectrum data at a test site at a specified speed. The typical roads include twisted roads, washboard roads and Belgian roads. This greatly reduces the test data processing time and simulation optimization time.

[0057] In summary, the present invention determines the force test scheme and calibration method of the suspension according to the force transmission characteristics of the suspension, ensures the accuracy of the test data, and only needs to perform the force test on the suspension system, without the need for special test equipment such as a six-component force test device, which can greatly reduce the test cost and time; and by optimizing the design of the loading box, it is ensured that the forces acting on the saddle by the loading box and the trailer are basically equivalent, which effectively greatly improves the credibility of the reliability test of the tractor's trunk loading at the saddle, and at the same time avoids abnormal damage to chassis components caused by the inequivalence of the tractor's trunk loading test and the tractor's trailer loading test.

[0058] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A method for designing a loading compartment for a tractor test, characterized in that: The following steps are involved: Step 1: Arrange strain gauges on the leaf spring guide arm, the lateral thrust rod and the leaf spring, and calibrate the strain-force relationship of the leaf spring guide arm, the lateral thrust rod and the leaf spring respectively; Step 2: Install the leaf spring guide arm, lateral thrust rod and leaf spring calibrated in step 1 onto the tractor to be tested, and measure the suspension load spectrum of the tractor to be tested during the load test with a hook; Step 3, establishing a tractor vehicle dynamics simulation model in the dynamics simulation software; Step 4, simulating the state of the tractor with a trailer, and correcting the dynamic simulation model of the tractor according to the actual measured force result of the suspension in step 2; Step 5, remove the trailer in the vehicle power simulation model in step 4, digitally model the loading compartment, set the loading compartment on the saddle of the vehicle power simulation model, set the density of the loading compartment, take the length, width and height of the loading compartment as variables, and assign initial values; Step 6: Set the convergence judgment conditions for the loading compartment parameter optimization and optimize the length, width and height of the loading compartment: Determine whether the loading compartment has converged. If so, proceed to step seven. If not, adjust the length, width, and height of the loading compartment, and re-determine whether the loading compartment has converged until the loading compartment has converged and then proceed to step seven. Step 7, extract the length, width, and height data of the optimized loading compartment, and record the set density of the loading compartment; Step eight, designing the loading compartment according to the length, width and height of the loading compartment optimized in step seven.

2. The design method of the loading compartment for tractor testing according to claim 1, characterized in that: In step 1, a strain gauge is set on the leaf spring guide arm; the leaf spring guide arm is rotated 90° according to the actual assembly angle and fixed on the fixture, a load is applied to the leaf spring guide arm shaft pin, and strain data of the leaf spring guide arm is collected at the same time, so as to obtain the relationship between the suspension X-axis load and strain; A strain gauge is arranged on the transverse thrust rod; one end of the transverse thrust rod is fixed to the fixed end, a load is applied to the other end of the transverse thrust rod, and strain data of the transverse thrust rod is collected at the same time to obtain the relationship between the Y-direction load and strain of the suspension; A strain gauge is set on the leaf spring, and the air suspension with the leaf spring equipped with the strain gauge is loaded on a tractor. By loading different masses on the trailer towed by the tractor and collecting the strain data of the leaf spring, the relationship between the leaf spring strain and the axle load is obtained, thereby obtaining the relationship between the suspension Z-direction load and strain.

3. The design method of the loading compartment for tractor testing as claimed in claim 2, characterized in that: The strain gauge on the leaf spring guide arm is arranged at the edge of the leaf spring guide arm along the length direction of the leaf spring guide arm; the strain gauge on the transverse thrust rod is arranged along the length direction of the transverse thrust rod; the strain gauge on the leaf spring is set on the side of the leaf spring close to the axle and arranged along the length direction of the leaf spring.

4. The design method of the loading compartment for tractor testing according to claim 1, characterized in that: In step 6, the convergence judgment conditions include: (1) The primary judgment condition: the deviation between the static axle load Mj of the vehicle model and the actual axle load Mc with the trailer is less than 5%; (2) Secondary judgment conditions: the deviation between the fatigue damage value of the lateral thrust rod and the fatigue damage value obtained by actual test is less than 10%, the deviation between the fatigue damage value of the leaf spring and the fatigue damage value obtained by actual test is less than 10%, and the deviation between the fatigue damage value of the leaf spring guide arm and the fatigue damage value obtained by actual test is less than 30%.

5. The design method of the loading compartment for tractor testing according to claim 1, characterized in that: In step five, the density of the loading compartment is set to the density of stone or the density of iron.

6. The method for designing a loading compartment for a tractor test according to claim 1, characterized in that: When the tractor to be tested has a total of 6 wheels and 4 of them are driving wheels, in step 5, the total mass of the loading compartment is set to 18 tons.

7. The method for designing a loading compartment for a tractor test according to claim 1, characterized in that: In step 2, when collecting the load spectrum, the tractor with trailer to be tested collects typical road load spectrum data at a test site at a specified speed, and the typical road surfaces include twisted roads, washboard roads and Belgian roads.

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