JP3223265B2 - Evaluation method of vehicle underbody characteristics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating underbody characteristics of a vehicle such as a shock absorber.

[0002]

2. Description of the Related Art Shock absorbers for vehicles such as automobiles are required to be inspected periodically because the damping force is deteriorated in accordance with the mileage, aging and the like. Various methods and devices for measuring the damping force have been conventionally proposed. For example, one of the inventors of the present invention has proposed a damping force measuring device which has a simple configuration and can quantitatively grasp the damping characteristics of a shock absorber (Japanese Patent Application No. Hei 0-110,056).
No. 7-31644).

[0003]

However, the shock absorber damping force measuring device has room for improvement as described below. First, when the quality of the shock absorber is determined by this damping force measuring device, the obtained measurement data is compared with the reference value of the vehicle manufacturer, and the determination is required. . Of course, it is necessary to obtain and prepare a reference value data collection as a premise for this comparison. In addition, when comparing the data, it is necessary to provide a data output function such as a memory to an arithmetic output unit or the like in the apparatus.

[0004] The present invention has such has been made in view of the improvement of the conventional device, as unnecessary and reference value data collection vehicle manufacturer, for each wheel of the vehicle under test Shock
It is an object of the present invention to provide a method capable of easily evaluating the characteristics of a test vehicle simply by obtaining characteristic values such as a damping force of a saw and a spring constant of a spring and performing predetermined processing.

[0005]

According to a first aspect of the present invention, there is provided a tester for measuring underbody characteristics of a vehicle, and a damping force of a shock absorber and a spring of each wheel of a vehicle under test using a ground contact load sensor. Characteristic values such as the spring constant of
And determine the vertical load, each of these wheels of characteristic values or, et al., Along with obtaining the difference between right and left front wheels of the left-right difference and the rear wheels of these values, while evaluating the characteristics of the vehicle under test These laterality, wherein each wheel of the characteristic values or, et al., along with obtaining the difference before and after the front and rear wheels of these values, by evaluating the characteristics of the vehicle under test these difference across comprehensively evaluating the characteristics of the vehicle under test And a method for evaluating underbody characteristics of a vehicle.

According to a second aspect of the present invention, a tester for measuring underbody characteristics of a vehicle and a ground contact load sensor are used.
Characteristic values such as the spring constant of the damping force and spring of the shock absorber for each wheel of the test vehicle, and determine the vertical load, each of these wheels characteristic values or, et al., The front wheels of the left-right difference and the rear wheels of these values with obtaining the difference between right and left, while evaluating the characteristics of the vehicle under test these laterality, wherein each wheel of the characteristic values or, et al., along with obtaining the difference before and after each of the front and rear wheels of these values, these difference across And evaluating the characteristics of the vehicle under test comprehensively by evaluating the characteristics of the vehicle under test.

According to a third aspect of the present invention, there is provided a step of obtaining characteristic values such as a damping force of a shock absorber and a spring constant of a spring of each wheel of a test vehicle using a tester for measuring underbody characteristics of the vehicle. , Using a ground load sensor
A step of determining the vertical load of each wheel of the test vehicle, the wheels of the characteristic values or, et al., And obtaining a difference between right and left of each of the front wheel between these values, the wheels of characteristic values or et of Calculating the left and right difference between the rear wheels,
An evaluation of the characteristics of the front wheel and the rear wheel of the vehicle under test based on the left / right difference is obtained by the formula of the left / right difference of each rear wheel / the larger of the left and right characteristic values of the front and rear wheels) × 100. A step of obtaining a total characteristic value of the characteristic values of the left and right wheels of the front and rear wheels; a step of obtaining a total ground contact load of the left and right ground loads of each of the front and rear wheels; / Calculating the front wheel load sharing ratio from the total contact load of the front and rear wheels;
Calculating a rear wheel load sharing ratio from the left and right total contact loads of the rear wheels / the total contact loads of the front and rear wheels; [(A-
B) / A larger value of A and B] × 100 (where A = the total characteristic value of the left and right front wheels /
Front wheel load sharing ratio, B = total left and right characteristic values of the rear wheel / rear wheel load sharing ratio. ) To obtain the evaluation of the characteristics of the test vehicle based on the front-back difference.

According to a fourth aspect of the present invention, the difference between the front and rear wheels is 30% or less, and the difference between the front and rear wheels is ± 3%.
When equal to or less than the 0%, there is the method of evaluating the suspension characteristics of claim 3 Symbol placement of the vehicle and judging characteristic of the test vehicle is good.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a shock absorber damping force measuring device for implementing a method for evaluating underbody characteristics of a vehicle according to the present invention. The damping force measuring device includes a wire type displacement sensor 4 for detecting a relative position between a vehicle body 1 and a wheel 3 connected to a shock absorber 2 to be measured of a vehicle under test, and a grounding load for detecting a grounding load of the wheel 3. A sensor (load cell main body) 6 and an arithmetic output unit 7 for arithmetically processing the detection signals of the wire type displacement sensor 4 and the ground load sensor 6, that is, the characteristic values of each wheel of the vehicle under test, are mainly constituted.

First, a wire type displacement sensor 4 for measuring a relative position between the wheel 3 and the vehicle body 1 has a wire tip portion thereof,
The wire type displacement sensor 4 is attached to the vehicle body 1 near the wheel 3 via a bracket 4a, and the sensor fixing jig 5 of the wire type displacement sensor 4 is fixed to the wheel 3, for example, the axle or the wheel side. A signal corresponding to the relative displacement of 3 is transmitted to the calculation output unit 7 via a cable. Here, the bracket 4a has a structure that can be detachably fixed to the vehicle body 1 by a clamp (fixing means) or a magnet.

On the other hand, the sensor fixing jig portion 5 is also configured as a structure that can be detachably fixed to the wheel 3. For example, FIG.
As shown in the figure, the jig body 50 on which the wire type displacement sensor 4 is fixed is engaged with the wheel 3 on the end side provided with the grip 51 for clamping operation, and the jig body is held on the other end side. Part 50
And a rod 5b, 5c which engages with the wheel 3 on a circumference of a predetermined angle from the rod 5a. If the grip 51 is rotated in a predetermined direction, the rods 5a to 5a 5c, the wire 3 can be supported at almost the position of the axle by holding the wheel 3 and holding the jig body 50 at the three points. , The rods 5a to 5c can be easily removed from the wheel 3.

A grounding load sensor 6 for detecting a grounding load of the wheel 3 uses a load cell body provided between the wheel 3 and a road surface and having a strain gauge 6a. With the ground load sensor 6 disposed on the road surface, the vehicle body 1 of the vehicle under test to be measured is mounted thereon, and the signal is sent to the calculation output unit 7 as a load.

The arithmetic output unit 7 is mainly composed of a microprocessor, an arithmetic program, a memory for storing shock absorber reference value data, and the like.
It is provided with an output unit such as a printer for outputting the calculation result and a display unit such as a CRT, and calculates a displacement x and a displacement speed v of the vehicle body 1 based on a signal from the wire type displacement sensor 4 and a ground load sensor. From the signal of 6, the load displacement Δ
Calculate w.

Next, the measurement of the shock absorber 2 using this damping force measuring device will be described with reference to the flowchart of FIG. First, in step S1, the vehicle body 1 such as a bumper is pushed up and down several times to artificially impart a substantially periodic up and down movement. According to the vertical movement of the vehicle body 1,
The vehicle body 1 is displaced with respect to the wheels 3, and the ground load sensor 6 fluctuates in load according to the vertical movement.

The operation output unit 7 determines in steps S2 and S3
While reading signals from the grounding load sensor 6 and the wire type displacement sensor 4, while continuously measuring the grounding load w and the displacement x of the vehicle body 1, in step S4, the piston of the shock absorber 2 is obtained from the differential value of the displacement x. The speed V is calculated. Then, in step S5, the above steps S2 to S
The damping force is calculated from the contact load w, the displacement x, and the piston speed V obtained in step 4, and in step S6, the calculation result is output to an output unit such as a printer or a display unit of the calculation output unit 7.

The calculation of the damping force of the shock absorber 2 performed in step S5 will be described with reference to FIG. The displacement x of the vehicle body 1 obtained from the detection signal of the wire type displacement sensor 4 is, as shown in FIG. 4 (A), the neutral point (displacement x = 0) of the shock absorber 2 which expands and contracts due to the periodic up and down movement at time t. Cross at ₁ and t ₂ respectively.

On the other hand, the ground load w of the wheel 3 obtained from the detection signal of the ground load sensor 6 is as shown in FIG. 4D, and a phase shift occurs with respect to the displacement x of the vehicle body 1. this is,
The contact load w that fluctuates due to the vertical motion of the vehicle body 1
As shown in FIG. 4B, the change in load according to the spring constant K of the spring supporting the vehicle body 1 is combined with the damping force generated by the shock absorber 2 as shown in FIG. . Here, the load fluctuation due to the spring is
In synchronization with the displacement x of the vehicle body 1, the amount of load variation by the spring is also zero at times t ₁ and t ₂ when the displacement x = 0.

Accordingly, the contact load w of the wheel 3 detected at times t ₁ and t ₂ at which the displacement x crosses the neutral point indicates the damping force of the shock absorber 2 by Fa and F shown in FIG.
b, and one elongation-side damping force Fa and one contraction-side damping force Fb can be obtained for one vertical movement of the vehicle body 1.

The piston speed V differentiated based on the displacement x has a sign corresponding to the expansion and contraction of the shock absorber 2, and as shown in FIG. 5, the piston speed at times t ₁ and t ₂ is Va and Vb in the figure, the damping forces Fa and Fb of the shock absorber 2 are equal to the piston speed V.
It can be obtained as a value corresponding to a and Vb.

The spring constant K of the spring is shown in FIG.
As shown in (A) to (C), from the vehicle body vertical displacement x = a when the vehicle body vertical velocity = piston speed V crosses 0 and the ground contact load w = b, K = b / a [Kg / mm ] Is required. In addition, the spring spring constant K
And the vertical displacement of the vehicle body when a static load is artificially applied to the vehicle body 1 such as a bumper.

FIG. 7 shows another example of the damping force measuring device. The fluid chamber 1 sandwiched between a base table 60 and an upper table 61 in place of the load cell body 6a in place of the ground load sensor 6 is shown.
3 and a pressure sensor section 14 for detecting the pressure of the fluid chamber 13
The rest is the same as in the case of FIG. The fluid chamber 13 is composed of, for example, a piston and a cylinder, and the fluid pressure changes according to the ground contact load of the wheel 3. Therefore, from the pressure receiving area and pressure of the fluid chamber 13, as in the case of FIG. Since the contact load w can be accurately measured, the damping force of the shock absorber 2 can be quantitatively and accurately measured with a simple configuration as in the case of FIG.

As described above, the damping force of the shock absorber 2 and the spring spring constant for one wheel are obtained, but the quality of the values is determined as described above.
It was necessary to judge by comparing with the reference value data of the vehicle manufacturer.

Therefore, in the present invention, first, as shown in FIG.
All three wheels of the vehicle under test _FL, 3_FR, 3_RL, 3
_RRThe characteristic value, for example, the reduction of the shock absorber.
Decay F_FL, F_FR, F_RL, F_RRAnd at the same time
Grounding load w_FL, W_FR, W_RL, W_RRAlso determine these measurements
A predetermined process is performed on the value. Here, the shock absolute
Damping force F_FL, F_FR, F_RL, F_RRThe value of
The value of the decay force Fa is used. Of course, the compression damping force F
The value of b can also be used.

The flow of this process is as shown in the flowchart of FIG. First, in step S11, FIG.
By the wire type displacement sensor 4 of the damping force measuring device of
Each wheel _{3 FL, 3 FR, 3 RL} , 3 damping force of the shock absorber of the _{RR F FL, F FR, F} RL, measuring the F _RR. In step S12, the ground loads _wFL , _wFR , _wRL , and _wRR of the wheels _3FL , _3FR , _3RL , and _3RR are measured by the ground load sensor 6 of the damping force measuring device in FIG. .

Next, in step S13, the operation output unit 7 of the damping force measuring device of FIG. 1, each wheel 3 _FL, 3 _FR,
3 _RL , 3 _RR Shock Absorber Damping Force F _FL , F _FR ,
From F _RL , F _RR , the left-right difference F _FL −F between the front wheels 3 _FL , 3 _FR
Calculate and find _FR . Similarly, in step S14, it calculates the rear wheel 3 _RL, 3 _RR laterality F _RL -F _RR between,
Ask for.

[0026] At step S15, (the front wheels, greater either right and left in each of the rear wheels laterality of each _{F FL -F FR, F RL -F} RR / front wheel 3 _FL, 3 _FR or the rear wheels 3 _RL, 3 _RR Using the equation (1) of (the damping force) × 100 (%), an evaluation of the characteristics of each of the front wheel and the rear wheel of the test vehicle based on the left / right difference is obtained by the calculation. Here, the determination of the quality is good if the left-right difference between the front wheel and the rear wheel is 30% or less.
If it exceeds 30%, it can be determined to be defective.

In step S16, the total left and right damping force F _FL + F _FR , F of the front wheels 3 _FL , 3 _FR or the rear wheels 3 _RL , 3 _RR is obtained.
Calculate and calculate _RL + F _RR . In step S17, the front wheels 3 _FL, 3 _FR or the rear wheels 3 _RL, 3 left and right total vertical load _RR w _FL + w _FR, calculates the w _RL + w _RR, determined.
Next, in step S18, the front wheel load sharing ratio R _WF is calculated from the left and right total ground load w _FL + w _{FR of} the front wheels 3 _FL and 3 _FR / the total ground load w _FL + w _FR + w _RL + w _RR of the front and rear wheels. Ask. Similarly, in step S19, the rear wheel load sharing ratio R _WR is calculated from the left and right total contact loads w _RL + w _{RR of the} rear wheels 3 _RL , 3 _RR / the total contact loads w _FL + w _FR + w _RL + w _{RR of the} front and rear wheels. Calculate and find. Here, the front wheel load distribution ratio R _WF, and a rear wheel load distribution ratio R _WR, by weight distribution between the front and rear by vehicle type, usually R _WF in the case of such FF vehicle
= 60% and R _WR = 40%. Of course, this value
It depends on the model.

In step S20, [(AB) / A or B, whichever is greater] × 10
Equation (2) of 0 (%) is used (where A = total damping force F _FL + F _{FR on} the left and right of the front wheel / front wheel load sharing ratio R _WF ,
B = Right and left side total damping force F _RL + F _RR / rear wheel load sharing ratio R _WR . ), The calculation is used to determine the evaluation of the characteristics of the vehicle under test based on the front-back difference. As a result, the weight distribution before and after the vehicle is taken into account.

That is, in the equation (2), when the front-back difference becomes a plus (+) percentage (%),
The ratio between the characteristic values before and after the load sharing ratio indicates that the degree on the front wheel side is large. On the other hand, if the front-rear difference becomes a negative (-) percentage (%), the ratio of the characteristic value of the rear wheel to the load sharing ratio is larger on the rear wheel side.

For example, the total left and right damping force F of the front wheels_FL
+ F_FR= 120Kg (value of extension damping force Fa)
Left and right total damping force F_RL+ F_RR= 80Kg (reduction on growth side)
The value of the damping force Fa), the weight distribution of the vehicle (front wheel load sharing ratio R)_WF
= 60%, rear wheel load sharing ratio R _WR= 40%), the difference before and after is [[(120 kg / 60%)-(80 kg / 40%)] / (120 kg / 60%)] x 100 (%) = (2 kg /%)-( 2Kg /%) / (2Kg /%) × 100 (%) = 0 (%). That is, the damping force ratio between the front and rear wheels is equal to the weight distribution ratio between the front and rear wheels.
Because they are equal, they are balanced with the weight distribution ratio, and 0 (%)
It becomes. Here, the quality judgment is made based on the front wheel and
If the front-rear difference of the rear wheel is ± 30% or less, it can be said that it is good,
If it exceeds ± 30%, it can be determined to be defective.

In step S21, the evaluation of the vehicle characteristics based on the left-right difference according to equation (1) and the evaluation of the vehicle characteristics based on the front-back difference according to equation (2) are comprehensively determined. That is, FIG.
As shown by a passing area 100 of 0, if the left-right difference between the front and rear wheels is 30% or less and the front-rear difference between the front wheels and the rear wheels is ± 30% or less, the shock absorber characteristics of the vehicle under test are provided. Can be determined to be generally good. In this evaluation, an output unit such as a printer or a display unit of a CRT is driven by the calculation output unit 7 in step S22 and displayed as specific data such as percentage data.

Further, as shown in FIG. 11, a display unit 7 on which display lamps 70a to 70c for pass / fail judgment are arranged.
0 is provided outside the calculation output unit 7 of the damping force measuring device (it may be incorporated in a part of the calculation output unit 7),
When the overall evaluation is unsuccessful, for example, a red (red) display lamp 70a is turned on, and when the overall evaluation is successful, a green (green) display lamp 70c is turned on. When a caution is issued, yellow (yellow) is used. Is turned on. Thereby, the comprehensive judgment result can be determined very quickly. It also greatly improves workability.

In the above embodiment, the evaluation of the characteristics of the vehicle under test based on the front-rear difference is performed for the front wheel total and the rear wheel total. In the present invention, a modified example thereof is shown in FIG. As described above, the difference between the front and rear of the left wheel and the difference between the front and rear of the right wheel can be individually obtained and determined. Further, in this embodiment, the shock absorber damping force is obtained as the characteristic value of each wheel. However, the present invention is not limited to this, and it is also possible to obtain and respond to a spring spring constant. Furthermore, as a tester for measuring the underbody characteristics of a vehicle, besides a shock absorber damping force measuring device, a compliance tester, a wheel alignment tester, and a rolling suspension tester can also be mentioned.

[0034]

As is apparent from the above description, the following excellent effects can be obtained by the method for evaluating underbody characteristics of a vehicle according to the present invention. (1) Using a tester having a relatively simple configuration, for example, a shock absorber damping force measuring device, it is possible to comprehensively evaluate and determine the characteristics based on the left-right difference and the front-rear difference between the front and rear wheels of the vehicle under test. it can. In other words, since it is based on the left and right balance of the front wheels or the rear wheels and the front and rear balance of the front and rear wheels in consideration of the weight distribution of the vehicle body, not only in the case of vehicles such as ordinary passenger cars, but also in the case of sports cars Even when the shock absorber is set to be stiffer as a whole irrespective of the proper weight, it can be applied without any problem because of the evaluation of the front-rear balance. Therefore, there is no need to switch devices as in the case of a soft type vehicle, a sports car type vehicle, and the like, and an extremely convenient general solution evaluation method can be obtained.
Further, as described above, in addition to the left-right balance, the front-rear balance taking into account the weight distribution of the vehicle body is taken into account for evaluation, so that a completely new evaluation method that has not been available in the past can be provided. Of course, the present invention can be applied to other testers who have been struggling in various ways.

(2) It is not particularly necessary to obtain a reference data collection of a vehicle maker and make a comparison at the time of determination, as in the prior art. Of course, as a result, the data comparison work becomes unnecessary. (3) In addition, since it is not necessary to hold the reference value data, it is not particularly necessary to provide a data output function such as a memory in an operation output unit or the like. (4) Further, if the characteristic evaluation of the vehicle under test is performed on a display unit such as a color-coded display lamp, the operator can know visually very simply and quickly.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of a tester for implementing a method of evaluating the underbody characteristics of a vehicle according to the present invention.

FIG. 2 is a schematic explanatory view showing an attached state of a wire type displacement sensor in the tester of FIG.

FIG. 3 is a flowchart showing a state of measurement by the tester of FIG. 1;

4 shows graphs of measurement results of the tester shown in FIG. 1 with respect to time, wherein (A) shows displacement x of the vehicle body, (B) shows load fluctuation caused by a spring, and (C) shows damping force of a shock absorber. (D) shows the grounding load w detected by the load cell.

FIG. 5 is a graph showing the relationship among the displacement x, the contact load w, and the piston speed V in the tester of FIG.

6A and 6B show graphs of measurement results of the tester shown in FIG. 1 with respect to time, in which FIG. 6A shows displacement x of the vehicle body, FIG. 6B shows vertical speed of the vehicle body, and FIG. .

FIG. 7 is a schematic configuration diagram showing an example of another tester for implementing the method of evaluating the underbody characteristics of a vehicle according to the present invention.

FIG. 8 is a schematic explanatory view showing one specific example of a method for evaluating the underbody characteristics of a vehicle according to the present invention.

FIG. 9 is a flowchart showing a state of measurement as one of the specific examples of FIG. 8;

FIG. 10 is a graph showing a state of comprehensive evaluation by the method for evaluating underbody characteristics of a vehicle according to the present invention.

FIG. 11 is a schematic explanatory view of a display unit for showing a state of evaluation by a method for evaluating underbody characteristics of a vehicle according to the present invention.

FIG. 12 is a schematic explanatory view showing another specific example of the method for evaluating the underbody characteristics of a vehicle according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Vehicle body under test 2 Shock absorber 3 Wheel 3 _FL- 3 _FR front wheel 3 _RL- 3 _RR rear wheel 4 Wire-type displacement sensor 5 Wire-type displacement sensor fixing jig part 6 Grounding load sensor 7 Calculation output part 13 Fluid chamber 14 Pressure sensor F _FL -F _FR front wheel characteristic value (shock absorber damping force) F _RL -F _RR rear wheel characteristic value (shock absorber damping force) w _FL -w _FR Front wheel ground contact load w _RL -w _RR front wheel Ground load

Claims (4)

(57) [Claims] A tester for measuring underbody characteristics of a vehicle,
Using the ground load sensor and the ground load sensor, determine the characteristic values such as the shock absorber damping force and the spring constant of the spring of each wheel of the vehicle under test, and the ground load.
Value or al, with determining the left-right difference of the left-right difference and the rear wheel of the front wheels of these values, while evaluating the characteristics of the vehicle under test These laterality, wherein the characteristic value for each wheel, these values By determining the front-back difference between the front and rear wheels, and by evaluating the characteristics of the vehicle under test by these front-back differences,
A method for evaluating underbody characteristics of a vehicle, wherein the characteristics of the vehicle under test are comprehensively evaluated. 2. A tester for measuring underbody characteristics of a vehicle,
Using the ground load sensor and the ground load sensor, determine the characteristic values such as the shock absorber damping force and the spring constant of the spring of each wheel of the vehicle under test, and the ground load.
Value or al, with determining the left-right difference of the left-right difference and the rear wheel of the front wheels of these values, while evaluating the characteristics of the vehicle under test These laterality, wherein the characteristic value for each wheel, these values Determining the front-rear difference of each of the front and rear wheels, and evaluating the characteristics of the vehicle under test based on these front-rear differences, thereby comprehensively evaluating the characteristics of the vehicle under test. How to evaluate characteristics. 3. A step of obtaining characteristic values such as a damping force of a shock absorber and a spring constant of a spring of each wheel of the vehicle under test using a tester for measuring underbody characteristics of the vehicle, and using a grounding load sensor. a step of obtaining a vertical load of each wheel of the test vehicle, the wheels of the characteristic values or, et al., and obtaining a difference between right and left of each of the front wheel between these values, the wheels of characteristic values or al, these And calculating the left / right difference between the rear wheels, and (the left / right difference between the front wheel and the rear wheel / the characteristic value of the left or right of the front wheel and the rear wheel, whichever is larger) × 100. Obtaining an evaluation of the characteristics of each of the front and rear wheels of the vehicle under test based on the left-right difference; obtaining a total characteristic value of the characteristic values of the front and rear wheels on the left and right; Total grounding of grounding load A step of obtaining a load, a step of obtaining a front wheel load sharing ratio from a total ground contact load of the left and right front wheels / a total ground load of the front and rear wheels, A step of obtaining a load sharing ratio; [(AB) / A or B, whichever is larger] × 10
By the equation of 0 (where A = total left / right total characteristic value of the front wheel / front wheel load sharing ratio, B = total left / right total characteristic value of the rear wheel / rear wheel load sharing ratio) Obtaining the evaluation of the characteristics of the vehicle under test. 4. When the left-right difference between the front and rear wheels is 30% or less and the front-rear difference between the front and rear wheels is ± 30% or less, it is determined that the characteristics of the vehicle under test are good. The method for evaluating underbody characteristics of a vehicle according to claim 3.