JP2756299B2 - Vehicle suspension rigidity measurement method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a method for measuring vehicle suspension stiffness characteristics, and more particularly to a vehicle suspension stiffness characteristic measurement for measuring suspension spring stiffness which is one of the basic characteristics of a vehicle. It is about the method.

[Conventional technology]

The vehicle wheels and the vehicle body are connected by a suspension, and the rigidity characteristics thereof are important factors that greatly affect the vibration, riding comfort, and maneuverability of the vehicle. Therefore, various measurements are performed using the characteristics of the suspension as basic vehicle characteristics.

When performing this kind of measurement, since it is extremely troublesome and practically impossible to perform the measurement by actually driving the vehicle, the same state as the actual running state is formed without actually running the vehicle. Various measurements are taken. As an apparatus for forming such a state similar to the actual running state, the left and right wheels of the vehicle are placed on a load table at the floor position of the vehicle basic characteristic measuring device, and the vehicle body is fixed to the ground. There is a so-called bump / re-band vehicle basic characteristic measuring device which moves up and down four wheels of a vehicle by a load table.

By the way, when measuring the suspension rigidity characteristics, it is a condition that the wheel is completely separated from the load table on the rib band side. As a method for detecting that the wheel has completely left the load table, there is a method in which a vertical load is monitored by a sensor, and when the output thereof becomes zero, it is determined that the wheel has left. . However, even if the load is actually zero, the output voltage is not guaranteed to be zero even if the load is actually zero, including the piezoelectric load sensor generally used in this kind of vehicle basic characteristic measuring device. For example, even if the wheels are away, if the wheel is drifted to the compression side, the force table will be driven in the downward direction forever, so that it cannot be used practically.

Therefore, conventionally, it is determined that the wheel is separated from the load table after the extreme lower target displacement point is set and sufficiently lowered.

[Problems to be solved by the invention]

By the way, in the measurement of the suspension rigidity characteristics, the range of the load sensor needs to be 500 kgf or more per one sensor, and the obtained measurement value must have an error within ± several kgf. In addition, it is necessary to take several minutes for the cycle of applying a force to the wheels to measure the suspension stiffness characteristics.

On the other hand, when using the piezoelectric load sensor,
It is difficult to hold the measured value for a long time due to easy charge outflow, and generally the fluctuation of static value, that is, the drift characteristic is poor. To guarantee the measurement, it is necessary to reset the load sensor to zero immediately before the measurement.

In this type of measurement, it is necessary to minimize the amount of displacement after the wheel is separated from the load table in order to reduce the time required for the measurement.

However, in the method of confirming that the wheel has separated from the load table as described above, the distance that the wheel separates from the load table is large, and the time that the wheel is separated is long, so that the wheel is actually reset to zero and then reset. There is a problem that it takes time before the load is applied, and the error generated during this time becomes so large that it cannot be ignored.

Accordingly, the present invention has been made in consideration of the above-described conventional problems, and has been made in view of the above-described conventional problems. The task is to provide a method.

[Means for solving the problem]

In order to solve the above-mentioned problems, a method of measuring vehicle suspension stiffness characteristics according to the present invention comprises: placing a vehicle wheel on a load table at a floor position of a vehicle basic characteristic measuring device; and fixing a vehicle body to the ground. A method in which the wheel is moved up and down by a load table, and the rigidity of the suspension is measured based on the load detected by the vertical load detector and the displacement detected by the vertical displacement detector. Before moving up and down, the force table at the floor position where the wheels of the vehicle are mounted is lowered by a predetermined amount, and a change in the output of the vertical load detector is monitored for each drop, and the change is monitored. When the value becomes equal to or less than a predetermined value, the output of the vertical load detector is reset after the force table is further lowered by a predetermined amount.

(Operation)

In the above procedure, before the wheels are moved up and down by the load table, the load table at the floor position on which the wheels of the vehicle are mounted is lowered by a predetermined amount, and the output of the vertical load detector is output at each drop. Is monitored, and when the change becomes a predetermined value or less, the output of the vertical load detector is reset after the force table is further lowered by a predetermined amount, so that the vertical load detector drifts. Can be reliably detected without detaching the wheel from the load table without lowering the load table far away from the wheel, and resetting the output of the vertical load detector under favorable conditions. The vehicle suspension stiffness can be accurately measured thereafter.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a mechanical portion of a vehicle basic characteristic measuring device used in carrying out the method of the present invention. The measuring device shown in the drawing is a seesaw having a platform which is flush with the left and right wheels of a vehicle as a test object. It employs a force-applying device. Since the force applying devices on which the front wheels and the rear wheels are respectively mounted have the same configuration, only one of them is shown in the figure.

The force applying device has a platform 13 having an intermediate portion supported on a bearing frame 12 fixed to the upper end of an elevating shaft 11 guided vertically by a guide (not shown) so as to swing left and right. A vertical displacement detector 12a is provided on the support portion, and a swing (roll) angle detector 12b is provided on the support portion. Below the left and right intermediate portion of the platform 13, upper and lower actuators 15 for driving the platform 13 in the vertical direction are respectively connected. Each actuator 15 is a hydraulic motor 15 servo-controlled by a servo valve.
a, and a pair of screw jacks 15b driven by the hydraulic motor 15a.
Is provided with a vertical displacement detector 15c.

Above the left and right intermediate part of the platform 13, a vertical moving frame 16 is provided via a piezoelectric vertical load detector (not shown). A longitudinally movable frame 18 movably guided is provided, and a left and right movable frame 19 guided movably in the left and right direction by a static pressure bearing is provided on the longitudinally movable frame 18. A force table (pad) 20 rotatably guided by a static pressure bearing is provided on the left and right moving frame 19, and a wheel of a vehicle as a test object is mounted on the force table 20.

The load table 20 is connected to the longitudinal frame 18 and the lateral frame 19 in the longitudinal direction and the lateral direction, respectively, and moves together with the longitudinal frame 18 according to the longitudinal movement. It moves right and left together according to.

The platform 13 is also hydraulically controlled by a servo valve (not shown), and a front / rear actuator 21 for driving the front / rear moving frame 18 in the left / right direction via a piezoelectric front / rear load detector (not shown) and a hydraulic control by a servo valve (not shown). A left / right actuator 22 for driving the left / right moving frame 19 in the left / right direction via a piezoelectric left / right load detector (not shown) and a wheel alignment measuring device 23 are provided. A rotation actuator 24, which is hydraulically controlled by a servo valve (not shown) and drives the force table 20 in a rotational direction via a piezoelectric torque detector (not shown), is connected to the force table 20.

Note that reference numeral 21a denotes a longitudinal displacement detector that detects displacement of the longitudinal frame 18, 22a denotes a lateral displacement detector that detects displacement of the lateral frame 19, and the rotation angle of the load table 20 is a rotation (not shown). The angle is detected by an angle detector. Further, the vehicle having the left and right wheels mounted on the load table 20 at the floor position is fixed to the ground by a fixing device (not shown).

The wheel alignment measuring device 23 has a sensor for detecting a steer angle, a camber angle, a caster angle, and the like of the tire, and outputs a measurement signal thereof.

FIG. 2 is a block diagram showing a circuit configuration of the basic characteristic measuring device. In FIG. 2, reference numeral 200 denotes a control device including a CPU, and the control device 200 includes a display device 20 such as a CRT.
1, floppy disk 202, printer 203, keyboard 2
04 and two input / output circuits 205 and 205 'are connected. The input / output circuit 205 is an actuator 15 for the left wheel, and the input / output circuit 205 'is an actuator 1 for the right wheel.
5 is provided for each, the input / output circuit 205
D / A converter 205a, A / D converter 205b and 205c
205 'is a D / A converter 205'a, A / D converters 205'b and 205'
c.

A / D converters 205b and 205'b are connected to displacement amplifiers 206 and 20.
Vertical displacement detector 12a input through 6 'respectively
Is converted into a digital displacement signal and input to the control device 200. A / D converters 205c and 205'c
Converts an analog load signal from the vertical load detector input via the load amplifiers 207 and 207 'into a digital load signal and inputs the digital load signal to the control device 200. The D / A converters 205a and 205'a convert the digital displacement target signal or the digital load target signal output by the control device 200 into an analog signal, and input the analog signal as a reference signal to the servo amplifiers 208 and 208 '. An analog displacement signal or an analog load signal is input to the feedback inputs of the servo amplifiers 208 and 208 ′ via the changeover switches 209 and 209 ′ which are switched by a control signal from the control device 200, and the output thereof is a reference signal and an analog load signal. The difference signal from the feedback signal is output,
This is supplied to the vertical actuator 15 as a control signal.

Next, when an embodiment of the vehicle suspension stiffness measuring method according to the present invention is carried out using the basic characteristic measuring device having the above-described configuration, the flowchart shown in FIG. This will be described below with reference to FIG.

In measuring the vehicle suspension stiffness, the left and right wheels of the vehicle are placed on the load table 20 at the floor of the vehicle basic characteristic measuring device, and the vehicle body is fixed to the ground.
After that, the operation of the control device 200 is started, and in step S1, the changeover switch 20
A control signal is sent to 9 and 209 'to set the control to displacement control. Subsequently, the process proceeds to step S2, where the force table 20 is lowered by a predetermined amount ΔD. Controller 200 for this reads a displacement signal D from the displacement detector 12a, and outputs from the displacement signal D ₁ read the less the predetermined amount [Delta] D to (D-ΔD) = D ₂ becomes displacement signal as the target signal .

Proceeding to step S3, where reading a load signal F ₁ from the load detector, the difference between the load signal F ₁ and the normal load F ₀ read the (F ₀ -F _1), i.e. the force table 20 Is changed by a predetermined amount ΔD. Then, it is determined whether the load difference obtained in step S3 (F ₀ -F ₁₎ is less than a predetermined value ΔF at step S4. The predetermined value ΔF is an extremely small value including 0, and is set by operating the keyboard 204 before the measurement is started, and is stored in the floppy disk 202, for example.

When the determination in step S4 is NO, that is, when the load change is larger than ΔF, the process returns to step S2, and the current displacement signal
A displacement signal obtained by subtracting ΔD from D ₂ (D ₂ −ΔD) is output as a target signal, and the force table 20 is further lowered by ΔD. Thereafter, the load difference becomes equal to or less than the predetermined value ΔF, and step S4
Steps S2 to S4 described above are repeatedly executed until the determination in step S2 becomes YES.

Determination is YES, that the load difference of the step S4 proceeds to step S5 when it becomes less than a predetermined value [Delta] F, where the time displacement signal D _n from the predetermined amount N · [Delta] D of (N is an arbitrary integer)
And outputs as the target signal to the displacement signal (D _n -N · ΔD) obtained by subtracting, lowering the pressure force table 20 only N · [Delta] D. Thereafter, the process proceeds to step S6, where a reset signal is output to the load amplifiers 207 and 207 '. With this reset signal, the load amplifiers 207 and 207 'are reset, the drift and the like of the piezoelectric load detector are cleared, and the output signal is surely set to 0 when the load is 0.

Subsequently, after waiting for T (several seconds) in step S7, the process proceeds to step S8, where the displacement signal is transmitted to the standard load F _0.
Set the signal corresponding to the displacement position at
Is raised to the standard load position, and the operation for vehicle suspension rigidity measurement, which is the original measurement, is started. The waiting in step S7 is for stabilization, but there is no problem if it is not provided.

The operation described above is summarized as shown in FIG.

(Effect)

As described above, according to the present invention, the wheels of the vehicle are placed on the load table at the floor position of the vehicle basic characteristic measuring device, and the wheels are moved up and down by the load table after the vehicle body is fixed to the ground. Before, the load table at the floor position where the wheels of the vehicle are placed is lowered by a predetermined amount, and a change in the output of the vertical load detector is monitored at each drop, and the change is equal to or less than a predetermined value. When the load table is further lowered by a predetermined amount, the output of the vertical load detector is reset, so that even if the vertical load detector includes a drift that has not been reset, the load table can be reset. Can be reliably detected without greatly lowering the force table, and resetting of the output of the vertical load detector can be performed under favorable conditions. Tanks suspension stiffness measurement can be performed accurately.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a mechanism of a basic characteristic measuring device used in the method of the present invention, FIG. 2 is a block diagram showing a circuit configuration of the basic characteristic measuring device used in the method of the present invention, and FIG. FIG. 4 is a flowchart showing the work performed by the control device in FIG. 2, and FIG. 4 is an explanatory diagram showing an example of the method of the present invention. 20 ... force table, 200 ... control device, 207, 207 '...
Load amplifier, 12a ... Vertical displacement detector.

Claims (1)

(57) [Claims] A vehicle wheel is mounted on a load table located on a floor surface of a vehicle basic characteristic measuring device, and the vehicle body is fixed to the ground. A method of measuring the stiffness of a suspension based on a load detected by a load detector and a displacement detected by a vertical displacement detector, wherein a floor surface on which a vehicle wheel is mounted before moving the wheel up and down by a load table. The force table at the position is lowered by a predetermined amount by a predetermined amount, and a change in the output of the vertical load detector is monitored at each drop. When the change becomes equal to or less than a predetermined value, the force table is further increased by a predetermined amount. A method for measuring a vehicle suspension stiffness, comprising: resetting an output of the vertical load detector after descending.