Method for testing strength of hybrid vehicle type transmission system

Abstract

The invention discloses a method for testing the strength of a hybrid vehicle type transmission system, which comprises the following steps of: 1, preparing: turning off a driving assistance system, and selecting an HEV / port mode as a driving mode; a transmission shaft test step: carrying out a linear acceleration cycle working condition test, a left-turn acceleration cycle working condition test and a right-turn acceleration cycle working condition test; after the transmission shaft testing step is completed, whether functional damage occurs to strongly-related parts of a transmission system or not and whether key torque attenuation is qualified or not are checked; a differential testing step: carrying out a left-turn cycle working condition test, a right-turn cycle working condition test and a work condition test around 8; after the differential testing step is completed, whether functional damage occurs to strongly-related parts of the transmission system or not and whether key torque attenuation is qualified or not are checked. According to the invention, when the vehicle transmission system strong correlation component reaches a predetermined working state, the impact damage resistance of the transmission system strong correlation component can be tested, and the design defects of the transmission system strong correlation component are exposed.

Description

Technical Field

[0001] The present invention relates to the field of vehicle testing, and in particular to a method for testing the strength of a hybrid vehicle transmission system. Background Art

[0002] With the continuous development of automobile technology, the ways of providing driving force for vehicles have also become diversified. At present, hybrid models are driven by the engine and motor in series and parallel. Due to the high speed and large output torque of the motor, the strength requirements of the transmission system are also very high. At present, the testing of transmission system components mainly relies on two aspects. On the one hand, it relies on the comprehensive vehicle test of the automobile company itself, and on the other hand, it relies on the bench durability test of the transmission system supplier. The superposition of these two test methods can verify the fatigue life and durability of the transmission system, which can generally meet the design and development of transmission system samples. However, since the strength verification of the transmission system parts is limited to simulation tests, it is impossible to imitate the structural strength of the transmission system parts under various extreme driving conditions. Once the strong related parts of the transmission system fail due to structural strength, the vehicle will break down, and in severe cases, it will cause vehicle safety accidents.

[0003] Therefore, it is necessary to develop a standardized test method to test the transmission system strength of hybrid vehicles. Summary of the invention

[0004] The purpose of the present invention is to provide a hybrid vehicle transmission system strength testing method to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: A method for testing the strength of a hybrid vehicle transmission system, 1. comprising the steps of: turning off the driving assistance system, and selecting the HEV / sport mode as the driving mode;

[0006] Drive shaft test steps: Carry out straight-line acceleration cycle test, left-turn acceleration cycle test and right-turn acceleration cycle test;

[0007] After completing the transmission shaft test steps, check whether there is functional damage to the transmission system's strongly related parts and whether the key torque attenuation is qualified;

[0008] Differential test steps: Carry out left-turn cycle test, right-turn cycle test and figure-8 test;

[0009] After completing the differential test steps, check whether there is functional damage to the transmission system's strongly related parts and whether the key torque attenuation is qualified;

[0010] Standard ramp and acceleration tests: carry out ramp start test, ramp climbing test, ramp reverse slope test, asphalt pavement acceleration test;

[0011] After completing the standard ramp and acceleration tests, check whether there is any functional damage to the strongly related parts of the transmission system and whether the key torque attenuation is qualified.

[0012] Preferably, the vehicle is kept fully loaded during the transmission shaft test and the differential test;

[0013] Standard ramp and acceleration tests, the vehicle is tested in both half-load and full-load states.

[0014] Preferably, the linear acceleration cycle test comprises the following steps: the wheels are aligned, the vehicle is put into D gear, and the vehicle is accelerated from a stationary state to more than 80 km / h with the throttle opening of 100%, and a cyclic operation is performed;

[0015] The left turn acceleration cycle test includes the following steps: turn the wheel fully to the left, engage the D gear, accelerate from a stationary state to more than 30 km / h with the throttle opening 100%, and perform a cyclic operation;

[0016] The right turn acceleration cycle test includes the following steps: turn the wheel fully to the right, engage the D gear, and accelerate from a stationary state to over 30 km / h with the throttle opening at 100%, and perform a cyclic operation.

[0017] Preferably, 4. the left turn cycle test comprises the following steps: engaging the D gear, starting the vehicle, accelerating along a circular path with the throttle opening at 100% until the steering degree is insufficient, then releasing the accelerator pedal, decelerating to a stop, and performing a cyclic operation;

[0018] The right turn cycle test includes the following steps: put the vehicle into D gear, start the vehicle, and accelerate along a circular path with a radius of 10m with the throttle opening at 100% until the steering degree is insufficient, then release the accelerator pedal and decelerate to stop, and perform the cycle operation;

[0019] The figure-8 working condition test includes the following steps: setting a first circular path and a second circular path that intersect, shifting the vehicle into the D gear, and driving along the first circular path to the intersection of the first circular path and the second circular path;

[0020] Then turn left at maximum acceleration, drive along the semi-second circular path, drive to the deceleration point of the second circular path with the throttle opening at 100%, release the accelerator pedal and decelerate, turn left and continue driving along the second circular path;

[0021] After driving to the intersection of the first circular path and the second circular path again, turn right with maximum acceleration, drive along the first circular path, drive to the deceleration point of the first circular path with the throttle opening of 100%, release the accelerator pedal and decelerate. Completing the above steps is a small cycle, and the cycle operation is performed.

[0022] Preferably, a high-low attachment docking test is also included: including a forward four-wheel passing test, shifting into D gear, driving on a friction road surface at a low speed, driving close to the high-low attachment dividing line for about 10 minutes, accelerating the four wheels at full throttle to pass the dividing line, then releasing the accelerator pedal to slow down to a stop, and performing a cyclic operation;

[0023] For the forward single-side wheel passing test, shift into D gear, drive the two wheels on one side on the friction road surface at a low speed, and when driving close to the high and low attachment dividing line, accelerate the two wheels on one side to pass the dividing line at full throttle, then release the accelerator pedal to slow down to a stop, and repeat the operation in a cycle;

[0024] Reverse four-wheel pass test, shift into R gear, drive at a low speed on a friction road surface, and when you are close to the high and low attachment dividing line, accelerate the four wheels to pass the dividing line at full throttle, then release the accelerator pedal to slow down to a stop, and repeat the operation;

[0025] For the reverse single-wheel pass test, shift into R gear, drive at a low speed on a friction road surface. When you drive close to the high and low attachment dividing line, accelerate with full throttle to pass both wheels on one side through the dividing line, then release the accelerator pedal to slow down to a stop, and repeat the operation.

[0026] Preferably, the hill start test includes the following steps: the vehicle is stopped at the bottom of the slope, then the vehicle is shifted to the D gear and driven to the middle of the slope, the foot brake is applied to stop the vehicle, and the vehicle is confirmed to be completely stopped without slipping, and then a user is simulated to start the vehicle in a stable manner, and finally the vehicle is accelerated to the top of the slope at full throttle, and several cycles are performed;

[0027] The ramp climbing test includes the following steps: the vehicle stops at the bottom of the slope, then shifts to D gear and drives to the middle of the slope, brakes the vehicle to stop, and makes sure that the vehicle is completely stopped without slipping, then simulates a user starting in a stable manner, and finally accelerates to the top of the slope at full throttle for several cycles;

[0028] The ramp reverse test includes the following steps: the vehicle stops at the bottom of the slope, then shifts to R gear and drives to the middle of the slope, brakes the vehicle to stop, and makes sure that the vehicle is completely stopped without slipping, then simulates a user starting in a stable manner, and finally accelerates to the top of the slope at full throttle for several cycles;

[0029] Completion of the above 4 cycles is counted as one large cycle, and a total of 20 large cycles are carried out.

[0030] Preferably, the hill start test is carried out on a 14% to 16% slope and a 18% to 20% slope, the slope ramp climbing test is carried out on a 30% slope, and the slope reverse slope test is carried out on a 20% slope.

[0031] Preferably, the asphalt pavement accelerated test includes:

[0032] Forward acceleration test: engage D gear, apply foot brake, throttle opening 100%, then release the brake pedal and accelerate to more than 130km / h at full throttle;

[0033] Reverse acceleration test: engage R gear, apply foot brake, throttle opening 100%, then release the brake pedal, accelerate to maximum speed at full throttle, and repeat several cycles.

[0034] Preferably, the preparation step further comprises:

[0035] Vehicle model selection: choose the model with the largest fully loaded mass, and the tire / rim combination with the largest inertia;

[0036] Vehicle status confirmation: whether the transmission system parts and chassis parts are in compliance with the design definition;

[0037] Whether the tire cold restart pressure meets the technical requirements of the vehicle;

[0038] Whether the vehicle's four-wheel alignment parameters meet the technical requirements.

[0039] Preferably, professionals are organized to conduct subjective evaluation before and after the test. The subjective evaluation items include the noise when the vehicle is stationary; the vehicle's performance in turning, U-turning, braking, and straight driving; the noise when the vehicle is fully turned, the clutch performance; the vibration during driving; and the vibration noise of each gear.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The present invention provides a hybrid vehicle transmission system strength testing method, which can test the impact damage resistance of the vehicle transmission system's strongly related components when the components reach a predetermined working state, expose the design deficiencies of the transmission system's strongly related components, and make adjustments and avoid them in the vehicle model development stage; simulate the worst user use scenarios, verify the reliability and durability of the transmission system, and ensure that the vehicle will not fail in extremely harsh environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 : Transmission system strength test flow chart;

[0043] Figure 2 : Subjective evaluation form for transmission system strength test;

[0044] Figure 3 : Vehicle loading method;

[0045] Figure 4 : Schematic diagram of transmission shaft test;

[0046] Figure 5 : Schematic diagram of differential test;

[0047] Figure 6 : Schematic diagram of high and low attachment docking test;

[0048] Figure 7 : Schematic diagram of standard hill start test. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] Please refer to the figure, this embodiment provides a hybrid vehicle transmission system strength test method, the transmission system strength test requires to be carried out according to the test process, see the attached Figure 1 ; Professionals are organized to conduct subjective evaluation before and after the test. For details of the evaluation form, please see the attached Figure 2 .

[0051] The transmission test mainly verifies the hybrid box, clutch device, flywheel, motor and transmission shaft. The load requirement before the test is full load. The specific loading method is shown in Figure 3. The driving assistance system is required to be turned off, and the driving mode is required to select HEV / sport mode. ① Straight line cycle: The vehicle is put into D gear, and accelerates from a stationary state to more than 80km / h with the throttle opening 100%, and performs several cycles. The specific operation method is shown in Figure 4 ② Left turn cycle: Turn the wheel fully to the left, shift into D gear, and accelerate from a stationary state to over 30km / h with the throttle opening at 100%, and perform several cycles. For details on the operation method, see Figure 4 ③Right turn cycle: Turn the wheel fully to the right, shift into D gear, and accelerate from a stationary state to over 30km / h with the throttle opening at 100%, and perform several cycles. For details on the operation method, see Figure 4 ④ The above three cycles are counted as one large cycle, and a total of three large cycles are carried out; ⑤ After each large cycle, check the lift to ensure that the transmission system's strong related parts are not functionally damaged, and the key torque attenuation cannot exceed the technical requirements.

[0052] The differential test is mainly to verify the hybrid case, differential, motor and drive shaft. The test load requirement is full load. For details on the specific loading method, please refer to the attached Figure 3, the driving assistance system is required to be turned off, and the driving mode is selected as HEV / sport mode. ① Left turn cycle: Put the vehicle in D gear, start the vehicle, and accelerate along a circle with a radius of 10m. When the throttle opening is 100%, accelerate until the steering degree is seriously insufficient, suddenly release the accelerator pedal, decelerate to stop, and perform several cycles. For detailed operation methods, see Figure 5 ②Right turn cycle: Put the vehicle in D gear, start the vehicle, and accelerate along a circle with a radius of 10m with the throttle opening at 100% until the steering degree is seriously insufficient. Suddenly release the accelerator pedal and decelerate to stop. Repeat several cycles. For detailed operation methods, see Figure 5 . ③ Figure-8 test: Put the vehicle in D gear, drive along the first circular path with a radius of 9m to the intersection of the first circular path and the second circular path, then pass through with maximum acceleration (preferably accelerate to 30km / h), turn left, and drive along the second circular path with a radius of 9m with the throttle opening of 100% to the deceleration point of the second circular path, release the accelerator pedal, and decelerate to an appropriate speed. Turn left and continue driving along the second circular path to the intersection of the first circular path and the second circular path, then pass through with maximum acceleration (preferably accelerate to 30km / h), turn right, and drive along the first circular path with a radius of 9m with the throttle opening of 100% to the deceleration point of the first circular path, release the accelerator pedal, and decelerate to an appropriate speed. Completing the above steps is a small cycle, and several cycles are carried out in total. For specific operations, see . Figure 5 ④ The above three cycles are counted as one large cycle, and a total of 100 large cycles are carried out. ⑤ During the test, the gearbox oil temperature is monitored and the oil temperature is required to be between 80℃ and 120℃; ⑥ After completing every 10 large cycles, the lift is used to check that the transmission system's strong related parts cannot have functional damage and the key torque attenuation cannot exceed the technical requirements.

[0053] The high and low attachment docking test verifies the hybrid box, differential, motor, and drive shaft. The test load requirement is full load. For details on the specific loading method, see the attached Figure 3 , the driving assistance system is required to be turned off, and the driving mode is selected as HEV / sport mode. ① Forward four-wheel pass test, put the car in D gear, drive at a speed of 20km / h on a road with an adhesion system of u≈0.15, and drive to about 10m away from the high and low adhesion dividing line. Full throttle acceleration is used to pass the dividing line, and then the accelerator pedal is released to slow down to a stop. Repeat several cycles. For detailed operations, see Figure 6 ② Forward single-side wheel passing test, shift into D gear, and drive on both sides of the road at a speed of about 20km / h on the road surface with a friction coefficient u≈0.15 in the adhesion system. When the distance to the high and low adhesion dividing line is about 10m, fully accelerate the two wheels on one side through the dividing line, then release the accelerator pedal to slow down to a stop, and repeat several cycles. For detailed operation, see Figure 6③ Reverse four-wheel pass test, shift into R gear, drive at a speed of about 20km / h on a road with an adhesion system friction coefficient u≈0.15, and when the distance to the high and low adhesion dividing line is about 10m, accelerate the four wheels through the dividing line at full throttle, then release the accelerator pedal to slow down to a stop, and repeat several cycles. For detailed operation, see Figure 6 ④ Reverse one-side wheel passing test, shift into R gear, drive at a speed of about 20km / h on a road with an adhesion system friction coefficient u≈0.15, and when the distance to the high and low adhesion dividing line is about 10m, fully accelerate one side of the two wheels through the dividing line, then release the accelerator pedal to slow down to a stop, and repeat several cycles. For specific operations, see Figure 6 ⑤ The above 4 cycles are counted as one large cycle, and a total of 10 large cycles are carried out. ⑥ After completing every 5 large cycles, check the transmission system's strong related parts on the lift to ensure that there is no functional damage, and the key torque attenuation cannot exceed the technical requirements. It is required that there is no abnormal sound during driving.

[0054] The standard ramp and acceleration tests are mainly used to verify the hybrid box and motor. The test load is divided into two forms: half load and full load. For details on the specific loading method, please refer to the attached Figure 3 , the driving assistance system is required to be turned off, and the driving mode is selected as HEV / sport mode. ① 14%~16% slope start: the vehicle stops at the bottom of the slope, then shifts to D gear and drives to the middle of the slope, stops with the foot brake, and makes sure that the vehicle is completely stopped and there is no slipping, then simulates the user to start in a stable manner. Finally, accelerate to the top of the slope with full throttle, and perform several cycles. For specific operations, see Figure 7 ②18%~20% slope start: Stop the vehicle at the bottom of the slope, then shift to D gear and drive to the middle of the slope, brake to stop, make sure the vehicle is completely stopped and there is no slipping, simulate the user to start smoothly. Finally, accelerate to the top of the slope with full throttle, and perform several cycles. For detailed operations, see Figure 7 ③ Maximum slope climbing (30% slope is recommended): Stop the vehicle at the bottom of the slope, then shift to D gear and drive to the middle of the slope, brake to stop, make sure the vehicle is completely stopped and there is no slipping, simulate the user to start smoothly. Finally, accelerate to the top of the slope with full throttle, and perform several cycles. For detailed operations, see Figure 7 ④ Maximum slope reverse slope (20% slope is recommended): the vehicle stops at the bottom of the slope, then shift to R gear and drive to the middle of the slope, brake to stop, make sure the vehicle is completely stopped and there is no slipping, simulate the user to start smoothly. Finally, accelerate to the top of the slope with full throttle, and perform several cycles. For specific operations, see Figure 7⑤ The completion of the above 4 cycles is counted as one large cycle, and a total of 20 large cycles are carried out. ⑥ Forward acceleration test on asphalt pavement: engage D gear, apply foot brake, throttle opening 100%, then release the brake pedal, accelerate to more than 130km / h at full throttle, and perform several cycles. ⑦ Reverse acceleration test on asphalt pavement: engage R gear, apply foot brake, throttle opening 100%, then release the brake pedal, accelerate to maximum speed at full throttle, and perform several cycles. ⑧ After the test is completed, check the lift to ensure that the strongly related parts of the transmission system cannot have functional damage, and the key torque attenuation cannot exceed the technical requirements.

[0055] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A hybrid vehicle transmission system strength test method, characterized in that: The preparation steps include: turning off the driving assistance system and selecting the HEV / sport mode for driving mode; Drive shaft test steps: Carry out straight-line acceleration cycle test, left-turn acceleration cycle test and right-turn acceleration cycle test; After completing the transmission shaft test steps, check whether there is functional damage to the transmission system's strongly related parts and whether the key torque attenuation is qualified; Differential test steps: Carry out left-turn cycle test, right-turn cycle test and figure-8 test; After completing the differential test steps, check whether there is functional damage to the transmission system's strongly related parts and whether the key torque attenuation is qualified; Standard ramp and acceleration tests: carry out ramp start test, ramp climbing test, ramp reverse slope test, asphalt pavement acceleration test; After completing the standard ramp and acceleration tests, check whether there is any functional damage to the strongly related parts of the transmission system and whether the key torque attenuation is qualified.

2. A hybrid vehicle transmission system strength testing method according to claim 1, characterized in that: The vehicle was kept fully loaded during the drive shaft test and differential test; Standard ramp and acceleration tests, the vehicle is tested in both half-load and full-load states.

3. A hybrid vehicle transmission system strength testing method according to claim 1, characterized in that: The straight-line acceleration cycle test includes the following steps: the wheels are aligned, the vehicle is put into D gear, and the vehicle is accelerated from a stationary state to more than 80 km / h with the throttle opening 100%, and the cycle operation is performed; The left turn acceleration cycle test includes the following steps: turn the wheel fully to the left, engage the D gear, accelerate from a stationary state to more than 30 km / h with the throttle opening 100%, and perform a cyclic operation; The right turn acceleration cycle test includes the following steps: turn the wheel fully to the right, engage the D gear, and accelerate from a stationary state to over 30 km / h with the throttle opening at 100%, and perform a cyclic operation.

4. A hybrid vehicle transmission system strength testing method according to claim 1, characterized in that: The left turn cycle test includes the following steps: put the vehicle into D gear, start the vehicle, and accelerate along a circular path with the throttle opening at 100% until the steering degree is insufficient, then release the accelerator pedal, decelerate to stop, and perform a cyclic operation; The right turn cycle test includes the following steps: put the vehicle into D gear, start the vehicle, and accelerate along a circular path with a radius of 10m with the throttle opening at 100% until the steering degree is insufficient, then release the accelerator pedal and decelerate to stop, and perform the cycle operation; The figure-8 working condition test includes the following steps: setting a first circular path and a second circular path that intersect, shifting the vehicle into the D gear, and driving along the first circular path to the intersection of the first circular path and the second circular path; Then turn left at maximum acceleration, drive along the semi-second circular path, drive to the deceleration point of the second circular path with the throttle opening at 100%, release the accelerator pedal and decelerate, turn left and continue driving along the second circular path; After driving to the intersection of the first circular path and the second circular path again, turn right with maximum acceleration, drive along the first circular path, drive to the deceleration point of the first circular path with the throttle opening of 100%, release the accelerator pedal and decelerate. Completing the above steps is a small cycle, and the cycle operation is performed.

5. The hybrid vehicle transmission system strength testing method according to claim 1, characterized in that: It also includes high and low attachment docking test: including forward four-wheel passing test, put the car in D gear, drive on friction road surface at low speed, drive to near high and low attachment dividing line for about 1 hour, accelerate the four wheels through the dividing line at full throttle, then release the accelerator pedal to slow down to stop, and repeat the operation; For the forward single-side wheel passing test, shift into D gear, drive the two wheels on one side on the friction road surface at a low speed, and when driving close to the high and low attachment dividing line, accelerate the two wheels on one side to pass the dividing line at full throttle, then release the accelerator pedal to slow down to a stop, and repeat the operation in a cycle; Reverse four-wheel pass test, shift into R gear, drive at a low speed on a friction road surface, and when you are close to the high and low attachment dividing line, accelerate the four wheels to pass the dividing line at full throttle, then release the accelerator pedal to slow down to a stop, and repeat the operation; For the reverse single-wheel pass test, shift into R gear, drive at a low speed on a friction road surface. When you drive close to the high and low attachment dividing line, accelerate with full throttle to pass both wheels on one side through the dividing line, then release the accelerator pedal to slow down to a stop, and repeat the operation.

6. A hybrid vehicle transmission system strength testing method according to claim 1, characterized in that: The hill start test includes the following steps: the vehicle stops at the bottom of the slope, then shifts to D gear and drives to the middle of the slope, brakes the vehicle to stop, and makes sure that the vehicle is completely stopped without slipping, simulates a user starting the vehicle in a stable manner, and finally accelerates to the top of the slope at full throttle for several cycles; The ramp climbing test includes the following steps: the vehicle stops at the bottom of the slope, then shifts to D gear and drives to the middle of the slope, brakes the vehicle to stop, and makes sure that the vehicle is completely stopped without slipping, then simulates a user starting in a stable manner, and finally accelerates to the top of the slope at full throttle for several cycles; The ramp reverse test includes the following steps: the vehicle stops at the bottom of the slope, then shifts to R gear and drives to the middle of the slope, brakes the vehicle to stop, and makes sure that the vehicle is completely stopped without slipping, then simulates a user starting in a stable manner, and finally accelerates to the top of the slope at full throttle for several cycles; Completion of the above 4 cycles is counted as one large cycle, and a total of 20 large cycles are carried out.

7. A hybrid vehicle transmission system strength testing method according to claim 6, characterized in that: The hill start test is carried out on a 14% to 16% slope and a 18% to 20% slope. The slope climbing test is carried out on a 30% slope. The slope reverse slope test is carried out on a 20% slope.

8. The hybrid vehicle transmission system strength testing method according to claim 1 is characterized by: Asphalt pavement accelerated testing includes: Forward acceleration test: engage D gear, apply foot brake, throttle opening 100%, then release the brake pedal and accelerate to more than 130km / h at full throttle; Reverse acceleration test: engage R gear, apply foot brake, throttle opening 100%, then release the brake pedal, accelerate to maximum speed at full throttle, and repeat several cycles.

9. A hybrid vehicle transmission system strength testing method according to claim 1, characterized in that: The preparation steps also include: Vehicle model selection: choose the model with the largest fully loaded mass, and the tire / rim combination with the largest inertia; Vehicle status confirmation: whether the transmission system parts and chassis parts are in compliance with the design definition; Whether the tire cold restart pressure meets the technical requirements of the vehicle; Whether the vehicle's four-wheel alignment parameters meet the technical requirements.

10. A hybrid vehicle transmission system strength testing method according to claim 9, characterized in that: Professional personnel are organized to conduct subjective evaluations before and after the test. The subjective evaluation items include the noise when the vehicle is stationary; the vehicle's performance in turning, U-turning, braking, and straight driving; the noise when the vehicle is fully turned, the clutch performance; the vibration during driving; and the vibration noise of each gear.

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