JPH0737928B2 - Vehicle 4-wheel steering characteristic inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention has made it possible to steer the rear wheels in response to steering of the front wheels by operating the steering wheel.
The present invention relates to a vehicle having a wheel steering device, and more particularly to a device for inspecting the characteristics of the four-wheel steering device.

(Prior Art) Conventionally, in steering a four-wheel vehicle, only the front wheels were normally steered by a steering wheel. However, if only the front wheels are steered, side slippage may occur in the rear wheels or the turning radius depending on the driving situation. However, there is a problem in terms of maneuverability and steerability, such as the fact that there is a limit to the effect of small turns, and in view of this point, a four-wheel steering system has recently been proposed that steers both the front wheels and the rear wheels.
Being researched.

That is, in a four-wheel steering system, if the rear wheels are steered in the same direction as the steering direction of the front wheels when traveling at a relatively high speed (this is referred to as in-phase steering), the front and rear wheels are simultaneously subjected to lateral force. Because of the addition of the steering wheel, there is no phase shift from the steering wheel steering, and the posture of the vehicle can be maintained almost on the tangent of the turning circle, and for example, lane changes during high-speed traveling can be performed smoothly. Further, when the rear wheels are steered in the opposite direction to the steered direction of the front wheels at the time of extremely low speed traveling (this is referred to as antiphase steering), the direction of the vehicle can be greatly changed, which is convenient for parallel parking and garage parking.

Considering that the front wheels are not steered largely at relatively high speeds, and that the front wheels are largely steered when traveling at relatively low speeds, the rear wheels are also steered in the range where the front wheels are steered small. It can be seen that a four-wheel steering device that steers the rear wheels in the opposite direction is required when the steering wheels are steered in the same direction and largely steered.

For this reason, a mechanism that can arbitrarily and variably control the ratio of the steered angle of the rear wheels to the steered angle of the front wheels, that is, the steered ratio, is provided. It has been proposed to variably control the vehicle to improve maneuverability and running stability. For example, as disclosed in Japanese Unexamined Patent Publication No. 61-108070, there is a four-wheel steering system in which the steering phase and the steering ratio are variably controlled according to the vehicle speed.

In a conventional vehicle that steers only two wheels, the front wheels are steered in proportion to the operation of the steering wheel, so it was sufficient to adjust the horizontal position of the steering wheel and the straight traveling direction of the front wheels. In the steering system, the front wheels are steered in proportion to the operation of the steering wheel, but the rear wheels are steered based on the steering characteristics that are determined according to the steering angle of the front wheels and the vehicle speed. However, there is a problem that the inspection of the steering characteristics of the rear wheels with respect to the front wheels is insufficient only by the conventional adjustment, and the running stability of the vehicle cannot be sufficiently ensured as it is. Therefore, from the above, the present applicant can inspect the steering characteristics of the rear wheels with respect to the steering of the front wheels by measuring the steering angles of the front wheels and the rear wheels, that is, the steering characteristics of the four-wheel steering system. In this way, the inspection device and method are proposed.

In this case, in order to measure the steered angles of the front wheels and the rear wheels, the front wheels and the rear wheels are placed on rotatable turntables, and the steering wheel is operated to steer the front wheels. The turning angle of the front wheels and the turning angle of the rear wheels that are steered according to the turning of the front wheels are measured to measure and inspect the turning characteristics of the rear wheels with respect to the front wheels. In order to smoothly steer the wheels placed on it, a full-float type that is freely rotatable and movable back and forth and left and right is often used.

(Problems to be Solved by the Invention) When a square wheel of a measurement vehicle is placed on such a full-float type turntable, the turntable can move so as to match the turning center of each wheel. However, a means for measuring the turning angle of each wheel mounted on the turntable (for example, the measuring plate is brought into contact with the side of the tire to measure the inclination of the measuring plate to measure the turning angle). Since the touch sensor) is positioned corresponding to the initial position of the turntable, when the turntable is moved as described above, the measuring means should be displaced from the wheels on the turntable. Therefore, there is a possibility that an error may occur in the measurement by this measuring means.
In addition, as an example of moving the full float type turntable, there is a case that the wheelbase of the vehicle has a dimensional variation, which may cause the turntable to move in the front-rear direction.

(Means for Solving Problems) The present invention, when a full-float type turntable is used, is directed to a turning angle measuring unit and a turntable on the turntable by the front-back movement of the turntable caused by the dimensional variation of the wheel base. In view of the problem of the front-rear position deviation from the wheels of the vehicle, it is intended to solve the above problem by providing an inspection device that corrects the front-rear position deviation so as to accurately measure the steering angle. As a means therefor, the inspection device of the present invention is provided with position detecting means for detecting the front-rear position of the wheel supported on the full float type turntable, and at the position of the wheel detected by the position detecting means. Accordingly, position adjusting means for performing front-rear position alignment with respect to the wheel of the turning angle measuring means for measuring the turning angle of the wheel is provided. It

(Operation) When the inspection device having the above-mentioned configuration is used, the wheel placed on the full-float type turntable is moved together with the turntable due to the dimensional variation of the wheel base and the turning angle of the wheel is measured. When there is a positional deviation in the front-rear direction with respect to the turning angle measuring means, the position deviation is detected by the position detecting means that detects the front-rear position of the wheel, and the position is detected according to the detected positional deviation. Since the adjusting means aligns the turning angle measuring means with respect to the wheels in the front-rear direction, the turning angle measuring means is always located at the correct position with respect to the wheels, and the measured turning angle is also accurate.

(Examples) Hereinafter, preferred examples of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view schematically showing a four-wheel steering system of a vehicle, in which front wheels 1a and 1b are steered by front wheel steering means 4 in response to an operation of steering wheel 3, and rear wheels 2a and 2b are It is adapted to be steered by the rear wheel steering means 10. In this rear wheel steering means 10, the steering amount of the front wheel steering means 4 is transmitted to the transmission bodies 5a, 5b.
The steering phase and the steering ratio are variably controlled according to the steering amount, the vehicle speed, etc.
The rear wheel steering means 10 controls the steering of the rear wheels 2a and 2b on the basis of the steering ratio to perform four-wheel steering.
The transmission bodies 5a, 5b are connected via the connection means 6, but the transmission bodies 5a, 5b are shafts for mechanically transmitting the steering of the front wheels 1a, 1b to the rear wheel steering means 10. Alternatively, it may be a cable for transmitting the steering of the front wheels 1a, 1b as an electric signal.

Here, first, a method for performing a characteristic inspection of the above-described four-wheel steering device will be schematically described. In order to perform this characteristic inspection, first, the front wheels 1a, 1b and the rear wheels 2a, 2b are placed on rotatable turntables respectively, and then the steering wheel is operated to steer the front wheels, At the same time this front wheel 1
Measure the steered angles of a, 1b2. When the front wheels 1a, 1b are steered in this way, the steering of the front wheels 1a, 1b is transmitted to the rear wheel steering means 10 via the transmission bodies 5a, 5b connected by the connection means 6, and the rear wheel rotations are performed. The rudder means 10 steers the rear wheels 2a, 2b in accordance with the steering amount of the front wheels 1a, 1b, the vehicle speed, etc., so that the steered angles of the rear wheels 2a, 2b at this time are also measured. In this case, the turntable supporting the rear wheels 2a, 2b is a full-float type turntable that is rotatable and movable back and forth and left and right, and position detecting means for detecting the front and rear positions of the rear wheels 2a and 2b is used. In addition to being provided, position adjusting means for moving the touch type sensor for measuring the steering angle of the rear wheels 2a, 2b back and forth is provided, and the rear wheel 2 detected by the position detecting means is provided.
The front and rear positions of the touch sensor are adjusted by the position adjusting means in accordance with the front and rear positions of a and 2b so that the rear wheel steering angle can be accurately measured by the touch sensor. Then, by these measurements, the change characteristic of the turning angle of the rear wheels 2a, 2b with respect to the turning angle of the front wheels 1a, 1b is detected, and this characteristic is compared and contrasted with a preset basic characteristic, Check for a match. If the measured characteristic does not match the basic characteristic, the four-wheel steering system is adjusted so that the desired characteristic can be obtained.

In general, the characteristic inspection is performed as described above. A specific example of the four-wheel steering device will be shown below, and the toe-in adjustment of front and rear wheels in a vehicle having this device and the characteristic inspection of the device will be performed. Method and apparatus will be described.

FIG. 2 is a schematic plan view showing an example of a four-wheel steering system.
The front wheel steering means 4 includes a front wheel steering rod 4a having a first rack that meshes with a first pinion 3a formed at a lower end of the steering wheel 3, and tie rods 4b and 4b connected to both ends of the rod 4a. Steering wheel 3 consisting of knuckles 4c and 4c connected to the outer ends of tie rods 4b and 4b.
The front wheel steering rod 4a is moved in the vehicle width direction in response to the operation of the knuckles 4c, 4c via the tie rods 4b, 4b.
The front wheels 1a and 1b are steered. Further, the front wheel steering rod 4a is formed with a second rack with which a second pinion 5c provided at the front end of the rotation transmission shaft (transmission body) 5a meshes, and the front wheel steering rod 4a is operated by operating the steering wheel 3. When is moved in the vehicle width direction, the rotation transmitting shaft 5a is simultaneously rotated via the second pinion 5c. This rotation is transmitted to the steering ratio variable mechanism 20 of the rear wheel steering means 10 via the connecting means 6 and the other transmission shaft 5b, and the rear wheels are moved in accordance with the steering phase and the steering ratio adjusted here. It is steered as described below.

On the other hand, the rear wheel steering means 10 includes a rear wheel steering rod 15 extending in the vehicle width direction, tie rods 16 and 16 connected to both ends of the rod 15, and external ends of the tie rods 16 and 16. The rear wheels 2a, 2b are steered by the knuckles 17, 17 that support the rear wheels 2a, 2b with the knuckle arm that is steerably supported and the rear wheel steering lock 15 moves in the vehicle width direction. . The rear wheel steering rod 15 is a cylinder fixed to the vehicle body and supporting the rear wheel steering rod 15 movably in the vehicle width direction.
11, a piston 12 that divides the internal space of the cylinder 11 into two parts, is fixed to the rear wheel steering rod 15, and is slidable inside the cylinder 11, and inside the left and right hydraulic chambers 13a and 13b that are defined by the piston 12. A hydraulic actuator composed of the neutral return springs 14a and 14b arranged in the is attached. Hydraulic lines 39a and 39b from the control valve 38 are connected to the left and right hydraulic chambers 13a and 13b of the hydraulic actuator, and the hydraulic actuator is actuated by the hydraulic pressure supplied from the control valve 38 so that the rear wheel steering rod 15 has a vehicle width direction. The rear wheels are steered. The hydraulic oil in the tank 35 is pressurized and supplied to the control valve 38 by the pump 36. The control valve 38 is of a known spool valve type, and has a cylindrical valve housing 38a integrally connected to the rear wheel steering rod 15 via an arm 15a, and is fitted in the valve housing 38a. And a spool valve 38b mounted therein.The hydraulic chamber 13a of the hydraulic actuator is arranged to move the valve housing 38a together with the rear wheel steering rod 15 in accordance with the movement of the spool valve 38b in the vehicle width direction. Supply of hydraulic pressure to 13b is selectively controlled. That is, by moving the spool valve 38b in the vehicle width direction, the spool valve 38b follows the spool valve 38b and the rear wheel steering rod 1
5 is moved and the rear wheels are steered.

The hydraulic lines 39a and 39b are respectively the hydraulic lines 37
It is connected to the normally-closed fail-safe solenoid valve 37 via a and 37b.
When 37c is energized and this valve 37 is opened, the hydraulic pressures in both hydraulic chambers 13a and 13b of the hydraulic actuator become equal, and the piston 12 is positioned in the neutral position by the biasing force of the neutral return springs 14a and 14b, and the rear wheel A fail-safe mechanism works so that the steering angles of 2a and 2b are always zero and the steering characteristics of the vehicle are in a two-wheel steering state.

The movement of the spool valve 38b in the vehicle width direction is performed by the turning ratio variable mechanism 20 which receives the rotation from the rotation transmission shaft 5b.
A description will be given in combination with the drawings. The turning ratio varying mechanism 20 includes a swing arm 22 whose base end is slidably supported by a U-shaped holder 21 via a support pin 22a, and the holder 21 is a casing fixed to the vehicle body (not shown). Above) spool valve 38b
Is rotatably supported via a support shaft 21a having a rotation axis l ₂ orthogonal to the movement axis l ₁ . The support pin 22a of the swing arm 22 is located at the intersection of the axes l ₁ and l ₂ and the rotation axis l ₂
It extends in a direction perpendicular to
By rotating about (rotation axis l ₂ ), the tilt angle formed between the support pin 22a at the tip and the movement axis l ₁ of the spool valve 38b, that is, the swing of the swing arm 22 about the support pin 22a. It is configured to change the inclination angle formed with respect to a plane (hereinafter, referred to as a reference plane) whose movement locus plane is orthogonal to the movement axis l ₁ .

Also, a ball joint is attached to the tip of the swing arm 22.
One end of the connecting rod 23 is connected to the other end of the connecting rod 23 via 23a, and the other end of the connecting rod 23 is connected to the other end of the spool valve 38b via a ball joint 23b. The spool valve 38b is displaced in the left-right direction in accordance with the displacement of the tip of the arm 22 in the left-right direction in FIG.

The connecting rod 23 has its ball point 23a.
Is supported slidably on the rotation imparting arm 24 via a ball joint 23c at a position close to the position. The rotation imparting arm 24 is composed of a large-diameter bevel gear rotatably supported on the moving axis l ₁ via a support shaft 24a, and the bevel gear has a bevel gear attached to the rear end of the rotation transmission shaft 5b. The gear 5d is meshed with each other, and the rotation of the steering wheel 3 is transmitted to the rotation imparting arm 24. Therefore, the rotation imparting arm 24 and the connecting rod 23 rotate about the moving axis l _{1 by} an amount corresponding to the rotation angle of the steering wheel 3, and the swinging arm 22 moves around the support pin 22a accordingly. When the pin 22a is oscillated and the axis of the pin 22a coincides with the moving axis l ₁ of the spool valve 38b, the pole joint 23a at the tip of the oscillating arm 22 only oscillates on the reference plane, and the spool valve 38b Is held stationary, but if the axis of the pin 22a is tilted with respect to the movement axis l _{1 and} the swing locus surface of the swing arm 22 deviates from the reference plane, the swing arm 22 centered around this pin 22a 3, the pole joint 23a is displaced in the left-right direction in FIG. 3, and this displacement is caused by the spool valve 38 via the connecting rod 24.
is transmitted to b, the spool valve 38b is moved along the movement axis l _1. That is, even if the swinging angle of the swinging arm 22 about the axis of the support pin 22a is the same, the displacement of the spool valve 38b in the left-right direction causes a change in the tilt angle of the pin 22a, that is, the rotation angle of the holder 21. It changes with it.

To change the rotation angle of the holder 21, a sector gear 25a as a worm wheel is attached to the support shaft 21a of the holder 21, and a worm gear 25b is meshed with the sector gear 25a. A bevel gear 25c is mounted on the shaft of the worm gear 25b, and a bevel gear 25d mounted on the output side of a stepping motor 26 as an actuator is meshed with the bevel gear 25c. By rotating the sector gear 25a, the inclination angle of the holder 21 with respect to the reference plane can be changed.
The steering angle of 2a, 2b, that is, the steering ratio and the steering phase of front and rear wheels 1a, 1b, 2a, 2b are controlled. Further, on the support shaft 21a of the holder 21, a turning ratio sensor including a potentiometer as a turning ratio detecting means for detecting the turning angle of the sector gear 25a corresponding to the actual turning ratio controlled by the stepping motor 26. 27 are provided.

The control of the turning ratio and the turning phase by the stepping motor 26 is performed by a controller 33 which receives a vehicle speed signal from a vehicle speed sensor 34 and is supplied with power from a battery 31. For example, as shown in FIG. 4, when the vehicle speed is zero. The steering ratio is maximized in the opposite phase, the two-wheel steering state is achieved in the zero phase when the vehicle speed is 30 km / h, and the steering ratio is maximized in the same phase when the vehicle speed is 120 km / h.

Next, an apparatus for inspecting the four-wheel steering characteristics of a vehicle having the above-described four-wheel steering apparatus will be shown, and its structure and characteristic inspection method will be described.

FIG. 5 is a plan view showing an inspection device 40 for toe-in adjustment and four-wheel steering characteristic inspection. This device 40 includes a front wheel static tester 41 for measuring front wheel toe-in angle, steered angle, etc. A front wheel guide 43 that guides the left and right front wheels to the front wheel static tester 41, a rear wheel static tester 45 that measures the rear wheel toe-in angle, a steering angle, etc., and a rear wheel static tester 45 that guides the left and right rear wheels. The rear wheel guide 47 and the rear wheel guide 47 are arranged side by side in a line as shown in the figure, and the vehicle is transported in the direction of arrow A to use the front and rear wheels as guides by the front wheel and rear wheel guides 43 and 47, respectively. It is designed to be positioned above the static testers 41 and 45. The device 40 includes a signal sending means 105 for sending a vehicle speed signal and the like to a vehicle to be inspected and a comparison inspection means 100 for comparing the four-wheel steering characteristic measured by the device 40 with a preset basic characteristic. Have
Therefore, the lines 100a to 100d for inputting the steering angle measurement values of the front and rear wheels are connected to the comparison inspection means 100, and the connector 105 connected to the controller of the vehicle is connected to the signal transmission means 105.
A line 105a having b is connected. Further, on the measuring plate 161 of the rear wheel angle measuring means 160 which constitutes the rear wheel static tester 45, position detecting means 169 for detecting the front and rear position of the rear wheel is attached to the front end thereof. The position detecting means 169 is, for example, a non-contact limit switch, which detects the front end of the rear wheel and detects the front and rear positions thereof.

A front view of FIG. 6 shows the front wheel static tester 41 in detail along arrow VI-VI, and a detailed plan view of this static tester 41 is FIG. The static tester 41 consists of a pair of left and right testers that are line-symmetrical in order to measure the toe-in angle and steered angle of the left and right front wheels, as shown in the figure. Are given the same numbers, and only one of them will be described. The static tester 41 includes a turntable 50 mounted on a support base 41a for supporting the front wheels so that the front wheels can be steered, and a toe-in angle of the front wheels which is brought into contact with the tire side surface of the front wheels placed on the turntable 50. A front wheel angle measuring means 60 for measuring a steering angle and the like, and a tester moving means 70 mounted on the support base 41a for moving the front wheel angle measuring means 60 in the vehicle width direction. The front wheel angle measuring means 60 has a measuring plate 61 which comes into contact with the tire side surface of the front wheel, and the measuring plate 61 is brought into contact with the tire side surface of the front wheel placed on the turntable 50 by the movement by the tester moving means 70. At the same time, it is configured by a touch sensor that measures the inclination of the measuring plate 61 to measure the toe-in angle and the steered angle.

The turntable 50 will now be described in detail with reference to FIGS. 8 and 9 and the structure of the turntable 50 will be described. The turntable 50 has a frame 51 made of a plurality of members fixedly mounted on the support base 41a, and a plurality of bearings 52 are fixedly mounted on the upper surface of the frame 51 side by side on the same circumference. The bearing 52 has a rotatable ball 52a, and the table 53 is rotatably supported by the ball 52a. The table 53 supports the front wheels by placing it on the table 53, and is provided with front and rear guides 53a, 53a for positioning the front wheels in the front-rear direction. Left and right guide plates 53b for positioning in the) direction are provided. Further, a rotary shaft 54 extending downward from the center of the table 53 and rotatably supported by the frame 51 via a radial bearing 51a is attached.
Encoder that detects the rotation angle of the table 53 at the lower end of 55
55 is installed. Table 53 on the frame 51
Plate 51 for smooth transportation of front wheels to
b and 51b are attached with the table 53 sandwiched in the front and back.

Next, the structures of the front wheel angle measuring means 60 and the tester moving means 70 will be described with reference to FIGS. 10 to 12. The front wheel angle measuring means 60 composed of a touch type sensor has a support shaft 62 attached to the frame 65 extending forward and a measurement plate 61 rotatably attached to the front end of the support shaft 62 via a ball joint 62a. There is. In this state, the measuring plate 61 is rotatable around the ball point 62a, but is held vertically with respect to the frame 65 by the compression spring 63a, the tension spring 63b and the link 63c as shown in the figure. It is to be noted that such an upright state is held when no external force acts on the measuring plate 61, and when the measuring plate 61 receives an external force, it is bent by the springs 63a and 63b or the link 63c is deformed. The measuring plate 61 is rotated around the ball joint 62a according to an external force. Therefore, when the measurement plate 61 is brought into contact with the tire side surface of the front wheel, the measurement plate 61 is tilted according to the tire inclination.Therefore, if the measurement plate inclination is measured, the toe-in angle and the steering angle of the front wheel are measured. , The camber angle, etc. can be measured. In order to measure the inclination angle of the measuring plate 61, three displacement measuring devices 64 are attached to the frame 65. The displacement measuring device 64 has a probe 64a which projects forward and is movable back and forth, and is mounted on the left and right and above the ball joint 62a as shown in FIG. The probe 64a comes into contact with the contact seat 61a fixed to the measurement plate 61 when the measurement plate 61 is in contact with the side surface of the tire. Since there is a difference in the amount of movement of the probe 64a in the front-rear direction (the amount of movement in the displacement measuring instrument 64 in the front-rear direction), the toe-in angle, the turning angle, the camber angle, etc. can be detected from this difference. Specifically, the displacement measuring devices 6 arranged on the left and right of the ball point 62a.
The toe-in angle and the steered angle can be measured from the difference between the front and rear movement amounts of the probe 64a of 4, and the displacement measuring device 64 arranged above the average value of the both movement amounts and the ball point 62a.
The camber angle can be measured based on the moving amount of. Therefore, if only the toe-in angle is adjusted and the steering angle is measured as in the present invention, only the two displacement measuring devices 64 arranged on the left and right sides of the ball joint 62a may be used. In addition,
These displacement measuring devices 64 and the like are covered with a cover 60a as shown by a chain double-dashed line in FIG.

The front wheel angle measuring means 60 having the above structure is supported by the tester moving means 70 via the frame 65 so as to be movable in the front-rear direction. Regarding the structure of the tester moving means 70 and the support of the front wheel angle measuring means 60 by the structure explain. The tester moving means 70 has a frame 71 fixedly mounted on the support base 41a, and a pair of left and right guide rods 72, 72 extending forward and backward by the frame 71 and a transport rod extending forward and backward between the guide rods 72, 72. 74 are supported. Two guide legs 67, 67 fixed to the lower surface of the frame 65 of the front wheel angle measuring means 60 are slidably fitted on the respective guide rods 72, whereby the front wheel angle measuring means 60 is It is supported by tester moving means 70 so as to be movable back and forth. Further, a screw is formed on the outer periphery of the transport rod 74, and the screw bush 66a of the transport leg 66 fixedly mounted on the lower surface of the frame 65 of the front wheel angle measuring means 60 is screw-engaged with the transport rod 74. There is. The transport rod 74 is rotatably supported by the frame 71, and the first sprocket 75a attached to the end of the transport rod 74 meshes with the second sprocket 75c attached to the shaft of the motor 76 via the chain 75b. By rotating the transport rod 74 by driving the motor 76, the entire front wheel angle measuring means 60 can be moved back and forth via the transport leg 66. In order to set the front and rear movement positions at this time, two limit switches 73, 73 spaced apart in the front and rear direction are attached to the frame 71 of the tester moving means 70, and the frame 65 of the front wheel angle detecting means 60 has the above-mentioned structure. A pair of switch plates 68, 6 facing the limit switch 73
8 is attached, the drive control of the motor 76 is performed by the operation of the limit switch 73 by the contact between the switch plate 68 and the limit switch 73, and the front wheel angle measuring means 60 is moved and positioned forward and backward.

Although the front wheel static tester 41 has been described above, the rear wheel static tester 45 will be described next. The rear wheel static tester 45 is also composed of a pair of left and right testers, and each tester is a full-float type turntable 150 that is rotatable and movable front, rear, left and right, rear wheel angle measuring means 160 composed of a touch type sensor, and a tester. It is composed of moving means 170. Turntable 150 is the 13th
As shown in the figure, a bearing made up of a frame 151 and a plurality of balls attached to the frame 151 (not shown, but the same as the bearing 52 of the front wheel turntable 50).
And a table 153 supported by the bearing, the rotary shaft 154 extending downward from the table 153 has a smaller downward extension amount than the rotary shaft 54 of the table 53 for the front wheels, and A square cross section 154a is at the lower end.
There is no encoder attached to detect the rotation of this axis. This is because the steered angle of the front wheels in a four-wheel steered vehicle is large, and the steered angle cannot be measured only by the front wheel angle measuring means 60. The front wheel angle measuring means 60 performs accurate measurement, and the encoder 55 measures the angle exceeding the above range, but the steering angle of the rear wheel is ± ± Since it is within the range of 5 °, the rear wheel angle measuring means
This is because 160 alone is sufficient for measurement. However, unlike the rotary shaft 154 of the table 153 in the rear wheel turntable 150, the rotary shaft 54 of the front wheel turntable 50 is rotatably supported by the frame 51 via the radial bearing 51a. There is no bearing support. Therefore, the table 153 is supported not only by the rotation of the front wheel turntable 50 but also by the bearing of a plurality of balls corresponding to the bearing 52 of the front wheel turntable 50. Here, an arrow XIII is attached to the lower end of the rotary shaft 154.
A square sectional view 154a is formed as shown in FIG. 13A showing a section taken along the line -XIII, and a pair of shaft holding plates 156, 156 are arranged so as to sandwich the square sectional portion 154a in the front and rear. These two shaft holding plates 156,156 are usually springs 1.
Although it is pushed outward by the 57, both shaft holding plates 156,1
When 56 is pressed, the square cross section 154a will be
It is held by the notches 156a and 156a of 156 and 156, and the rotary shaft 15
4 is fixedly held. The rear wheel angle measuring means 160 for measuring the toe-in angle, the turning angle, etc. of the rear wheels and the tester moving means 170 for moving the rear wheel angle measuring means 160 in the vehicle width direction (left and right direction) are the front wheel static tester 41.
Since the function and the essential structure are the same as in the case of 1, the description thereof will be omitted.

However, as shown in FIG. 5, the measuring plate 161 of the rear wheel angle measuring means 160 is provided with position detecting means 169 for detecting the front-rear position of the rear wheel placed on the turntable 150 at the front end thereof. In addition, the tester moving means 170 is a support base 41a.
It is attached via a position adjusting means (not shown). This position adjusting means supports the rear wheel angle measuring means 160 and the tester moving means 170 so as to be movable in the front-rear direction with respect to the support base 41a, and detects the rear wheel on the turntable 150 detected by the position detecting means 169. The rear wheel angle measuring means 160 and the tester moving means 170 are moved back and forth so that the center of the measuring plate 161 of the rear wheel angle measuring means 160 coincides with the center position for position adjustment.

Next, a front wheel guide that guides the front wheel and the rear wheel to the front wheel static tester 41 and the rear wheel static tester 45, respectively.
The 43 and the rear wheel guide 47 will be described. Since both guides 43 and 47 have the same shape, the front wheel guide 43 is shown in FIG. 14 and will be described based on this. The front wheel guide 43 has a pair of guide bodies 90, 90 each having a guide groove 90a for guiding the left and right front wheels toward the static tester 41, and these guide bodies 90, 90 are in the vehicle width direction (left and right direction). It is freely movable to. In addition, guide plates 91, 91 that are opened rearward in a "C" shape are attached to the guide groove 90a so as to guide the front wheel properly. Frames 96 and 97 facing the outer side surfaces of both guide bodies 90 and 90 are provided with rotatable first and second arms 92a and 92b extending rightward in the drawing.
Both arms 92a and 92b are connected by a first connecting rod 93. The first arm 92a is connected to the guide body 90 that supports the right front wheel by the second connecting rod 95 as shown in the figure, and is a frame that faces the outer surface of the guide body 90 that supports the left front wheel.
97 is forward from the mounting portion of the second arm 92b (left side in the figure)
A third arm 92c extending to the second arm 92b is rotatably attached integrally with the second arm 92b. The third arm 92c is attached to a guide body 90 that supports the left front wheel by a third connecting rod 94 as shown in the drawing. It is connected. Therefore, the first connecting rod
If 93 is moved in the vehicle width direction by a cylinder (not shown) or the like, both guide bodies 90, 90 can be moved in opposite directions in the vehicle width direction, and even if the treads of the front wheels are different, Both guides 90,90 according to the tread
The distance can be adjusted.

Further, lifters 48 and 49 for raising and supporting the front and rear bodies of the front wheel guide 43 are provided (see FIG. 5). As shown in FIG. 15 showing a cross section taken along the arrow XV-XV in FIG. 5, this lifter comprises a frame 105 and a cylinder 102 fixed to the frame 105 and extending vertically.
The rod 101 of 02 is projectable upward and has a groove 1 at its upper end.
A head 101a having 01b is attached. Therefore, when the rod 101 of the cylinder 102 is extended upward, the groove 101b of the head 101a receives the side sill of the vehicle body and lifts the vehicle body. When front and rear wheels are placed on the full float type and turntable, respectively, when external force is applied to the vehicle body in the horizontal direction, the turntable is moved and the vehicle body is moved, and the measurement by the front wheel and rear wheel angle measuring means becomes inaccurate. However, by supporting the vehicle body by raising it by the lifter, it is possible to prevent the vehicle body from being moved even when an external force in the horizontal direction is applied to the vehicle body. Furthermore, by lifting the vehicle body with the lifter, the weight of the vehicle body added to the tire placed on the turntable can be reduced. As a result, the deformation of the tire is reduced, and when measuring the turning angle by the touch sensor, this sensor is less affected by the deformation of the tire, and the error in the measured value is also reduced. The load is reduced and the turntable can be rotated smoothly.

A method of inspecting the four-wheel steering characteristics of a vehicle equipped with a four-wheel steering device using the above-described inspection device 40 will be described by taking the four-wheel steering vehicle shown in FIG. 2 as an example. First, after extending the cylinders 158, 158 of the rear wheel turntable 150 and fixing the rotary shaft 154 by the shaft holding plates 156, 156,
The vehicle is conveyed onto the device 40 from the right side in FIG. 5 in the direction of arrow A, and the front and rear wheel guides 43 and 47 are used to move the front wheels 1a and 1b and the rear wheels 2a and 2b to the front and rear wheel static testers, respectively. Place on top of 41,45. Then, the heads 101a of the lifters 48 and 49 are moved upward to move the heads 101a.
By a, the side sill portion of the vehicle body is lifted to reduce the load from the front and rear wheels to the turntables 50 and 150, and the vehicle body is held to prevent the vehicle body from moving in the horizontal direction due to an external force. The lifting force of the vehicle body by the lifters 48, 49 is set so that the table 53, 153 has a load enough to smoothly rotate the tables 53, 153 in accordance with the turning of the front wheels and the rear wheels. Then, the cylinders 158, 158 of the rear wheel turntable 150 are contracted to rotate the shafts by the shaft holding plates 156, 156.
The fixed holding of 154 is released and the table 153 is brought into a full float state.

From this state, first, the toe-in adjustment of the front wheels and the rear wheels is performed. This toe-in adjustment is performed by steering means for the front and rear wheels.
The front and rear wheels are separately carried out in a state where the connection of the connecting means 6 of 4, 10 is released. In this case, the toe-in angle is measured by the angle measuring means 60,160 composed of the touch type sensors of the front and rear wheel static testers 41,45, and the toe-in angle is measured with the front and rear wheels facing straight and the steering wheel facing horizontally. The angle is adjusted to have a predetermined value, and then the front wheel and the rear wheel steering means are connected by the connecting means 6, but the description of the specific adjusting method will be omitted. However, when adjusting the toe-in of the rear wheel, the position detecting means 169 detects the front-back position of the rear wheel placed on the turntable 150, and in accordance with this, the measuring plate 161 of the rear-wheel angle measuring means 160 is placed at the center of the rear wheel. The position adjusting means adjusts the front-rear position of the rear wheel angle measuring means 160 so that the centers coincide with each other. Therefore, even if there are variations in the dimensions of the wheel base, the center position of the rear wheel and the measurement plate 161
The center position of the vehicle is accurately aligned, and the measurement of the toe-in angle by the rear wheel angle measurement means 160 and the measurement of the rear wheel steering angle described below are accurate. The toe-in adjustment here includes not only so-called wheel toe-in adjustment but also adjustment in the toe-out direction.

After the toe-in adjustment, the four-wheel steering characteristic is inspected. The adjustment of the four-wheel steering characteristics is performed by measuring and inspecting the relationship between the steered angles of the front wheels 1a, 1b and the rear wheels 2a, 2b associated with the operation of the steering wheel 3. A specific inspection method will be described.

First, a simulated vehicle speed signal (for example, a vehicle speed signal corresponding to a vehicle speed of 120 Km / H) is sent from the signal sending means 105 to the controller 33 via the line 105a so that the turning phase is the same phase and the turning ratio is maximized. To do. In this state, operating the steering wheel 3 to steer the front wheels 1a, 1b, the rear wheels 2a, 2b
The steering angles of these front and rear wheels are also measured by the front and rear wheel static testers 41 and 45 because they are steered in the same phase. The graph of FIG. 16 shows an example of the relationship between the front wheel steering angle and the rear wheel steering angle measured in this way. In this graph, the vertical axis shows the rear wheel steering angle, the horizontal axis shows the front wheel steering angle, and the upper side of the vertical axis and the right side of the horizontal axis show the steering of the rear wheels and the front wheels to the right. There is. As can be seen from this graph, when the front wheels are steered to the right, the rear wheels are steered to the right accordingly (to the same phase). Is gradually reduced and the steering angle is not steered beyond a predetermined steering angle (right maximum steering angle) θ ₁ . The same applies to the case where the front wheels are steered to the left, and the rear wheels are steered in the same phase and gradually decreasing the change to the left maximum steering angle θ ₂ .

Next, a simulated vehicle speed signal (for example, a vehicle speed signal corresponding to a vehicle speed of 30 Km / H) is sent from the signal sending means 105 to the controller 33 via the line 105a so as to make the steering phase zero phase. In this state, operate the steering wheel 3 to move the front wheels.
Even if the 1a and 1b are steered, the rear wheels 2a and 2b should be kept in the zero phase and not steered. The steered angles of these front and rear wheels are measured by the front and rear wheel static testers 41 and 45, and FIG. 17 shows an example of the relationship between the steered angles of the front wheels and the steered wheels of the rear wheels thus measured. Is a graph of. As can be seen from this graph, when the front wheels are steered to the right, the rear wheels are hardly steered, and only very small steerings θ ₁ and θ ₂ occur due to dimensional errors and the like.

Furthermore, a simulated vehicle speed signal (for example, a vehicle speed signal corresponding to a vehicle speed of 0 Km / H) is sent from the signal sending means 105 to the controller 33 via the line 105a so that the turning phase is reversed and the turning ratio is maximized. To do. In this state, operating the steering wheel 3 to steer the front wheels 1a, 1b, the rear wheels 2a, 2b
Is steered in the opposite phase, the steered angles of these front and rear wheels are measured by the front and rear wheel static testers 41, 45. The graph of FIG. 18 shows an example of the relationship between the front wheel turning angle and the rear wheel turning angle thus measured. As can be seen from this graph, when the front wheels are steered to the right, the rear wheels are accordingly steered to the left (to the opposite phase). Is gradually reduced and the steering angle is not steered beyond a predetermined steering angle (left maximum steering angle) θ ₁ . The same applies to the case where the front wheels are steered to the left, and the rear wheels are steered in the opposite phase while gradually reducing the change to the right-side maximum steering angle θ ₂ .

In the measurement of the steered angles of the front wheels and the rear wheels by the static testers 41 and 45, the steered angle of the front wheels is a front wheel composed of a touch type sensor in the range where the steered angle is small (± 5 ° range). The angle is measured by the angle measuring means 60, and the angle exceeding this range is measured by the encoder (rotation angle detector) 55 attached to the lower end of the rotary shaft 54 of the turntable 50, while the rear wheel steering angle is touched. It is measured by the rear wheel angle measuring means 160 composed of a linear sensor.

Measured as described above, when various vehicle speed signals are input, desired basic characteristics are set in advance for each of the characteristics of the rear wheel steering angle change corresponding to the front wheel steering angle, The comparison inspection means 100 compares the characteristics measured by the above-described measurements with the basic characteristics to determine whether the measured characteristics fall within the required range of the basic characteristics, and the maximum turning angles θ ₁ and θ ₂
Is checked whether it is within a predetermined range as a preset basic characteristic, and if it does not match the basic characteristic, the steering characteristic is adjusted to match it.

Next, an example of another inspection method according to the present invention will be described.
For this inspection, the steer rig wheel 3 is reciprocated leftward and rightward about its horizontal direction, and the front wheels 1a, 1b are steered back and forth within a predetermined range centered on its straight ahead direction. In this case, the front wheel steering angle range may be a small range, for example,
In this example, it is about ± 3 °. At this time, the front wheel angle measuring means 60 composed of a touch type sensor measures the steering angle with high accuracy. Since the rear wheels 2a, 2b are also steered by the steering of the front wheels, the steering angle of the front and rear wheels at this time is measured to perform the characteristic inspection. It is preferable to input a vehicle speed signal that maximizes the turning ratio to the controller 33 so that the rudder can be easily measured. Therefore, the connector 105b of the signal transmission means 105 is connected to the controller 33 instead of the vehicle speed sensor of the vehicle to be inspected, and the vehicle speed signal (vehicle speed) that maximizes the turning ratio is transmitted from the signal transmission means 105 via the line 105a. A vehicle speed signal corresponding to 0 km / h or 120 km / h) is sent to the controller 33.

The steering angle of the front wheels and the rear wheels when the front wheels are steered by operating the steering wheel under the above conditions is measured by the angle measuring means 60,160 consisting of the touch type sensors of the front and rear wheel static testers 41,45. taking measurement. When one example of the measurement results is shown by showing the rear wheel turning angle on the vertical axis and the front wheel turning angle on the horizontal axis, as shown by the solid line in the graph of FIG. can get. The reason why the locus having hysteresis is obtained is that there is backlash in the connection system between the front wheel steering means and the rear wheel steering means. In this case, the adjustment of the rear-wheel steering angle when the front-wheel steering angle is zero is adjusted based on either the right or left steering of the front wheels. Since the steered angle of the rear wheels is deviated and the running stability is impaired, in the present invention, in the comparative inspection means 100 receiving the above measurement signal, the curve β representing the midpoint of both loci is the origin on the graph. I try to inspect whether or not it passes. That is, it is inspected whether or not the trajectory curve obtained by turning the steering wheel to the right and the trajectory curve obtained by turning the steering wheel to the left are substantially point-symmetrical with respect to the origin. Then, the rear wheel steering means is adjusted so that the curve β passes through the origin.

In addition, in the vehicle using the four-wheel steering means shown in FIGS. 2 and 3, the neutral return springs 14a, 14b are pre-compressed, so that the rear wheels 2a, 2b are in the straight traveling position (the steering angle is When the steering wheel is steered to the left or right from the zero position, the trailing curve is almost zero in the dead zone where the rear wheels are not steered relative to the steered front wheels (the front wheel steering angle in the graph is zero). (Horizontal part) occurs. Therefore, for example, the front wheel steering angles α ₁ and α ₂ when this dead zone occurs are read, and whether or not the median value of both the steering angles α ₁ and α ₂ becomes zero, that is, both dead zones are centered around the origin. You may make it inspect whether it is a point object.

In this example, the method for inspecting the four-wheel steering characteristics has been described with reference to a vehicle having an electrohydraulic four-wheel steering mechanism that controls the turning ratio and the turning phase according to the vehicle speed. The invention is not limited to this, and the same applies to a vehicle having a mechanical mechanism that mechanically transmits the steering of the front wheels to the rear wheels and controls the steering of the rear wheels according to the steering of the front wheels. Is.

Further, the inspection device and method according to the present invention are not limited to the inspection shown in the present example, and various types of four wheels such as an inspection of the operation of the fail-safe mechanism and an inspection of the change of the rear wheel steering angle corresponding to the change of the vehicle speed can be performed. Used for inspection of steering characteristics.

(Effect of the Invention) As described above, according to the present invention, the position detecting means for detecting the front and rear position of the wheel supported on the full float type turntable is provided, and the position detecting means detects the position. Since the position adjusting means for adjusting the front and rear position of the turning angle measuring means for measuring the turning angle of the wheel according to the position of the wheel is provided, it is mounted on the full float type turntable. When the placed wheel is moved together with the turntable due to the dimensional variation of the wheel base, etc., and is located in front of and behind the turning angle measuring means for measuring the turning angle of this wheel, The position deviation is detected by the position detecting means for detecting the front and rear positions of the wheels, and the turning angle measuring hand is detected by the position adjusting means according to the detected position deviation. Since the front-rear position alignment with respect to the wheel of the step is performed, the steered angle measuring means can be always positioned at the correct position with respect to the wheel, and the measured steered angle becomes accurate.

[Brief description of drawings]

FIG. 1 is a plan view schematically showing a four-wheel steering system for a vehicle, FIG. 2 is a plan schematic view of the four-wheel steering system, and FIG. 3 is a perspective schematic view showing a turning ratio varying mechanism. Is a graph showing the relationship between the vehicle speed and the turning angle, FIG. 5 is a plan view showing the inspection device, FIGS. 6 and 7 are front views and plan views of the front wheel static tester, and FIGS. 8 and 9 are Front sectional view and side view showing a front wheel turntable, FIGS. 10 to 12 are front views, plan views and side views showing front wheel angle measuring means and tester moving means, and FIG. 13 is a rear wheel turntable. A front view showing the table, FIG. 13A is a sectional view showing the turntable along the arrow XIII-XIII, FIG. 14 is a plan view showing a front wheel guide, FIG. 15 is a sectional view showing a lifter, and FIG. FIG. 19 is a graph showing an example of the measurement results of the change in the rear wheel steering angle with respect to the front wheel steering. is there. 4 ... Front wheel steering means, 6 ... Connecting means 10 ... Rear wheel steering means, 14a, 14b ... Neutral return spring 20 ... Steering ratio variable mechanism, 26 ... Stepping motor 27 ... Steering ratio sensor , 33 …… Controller 34 …… Vehicle speed sensor, 38 …… Control valve 40 …… Inspection device, 41,45 …… Static tester 43,47 …… Guide, 48,49 …… Lifter 50,150 …… Turntable, 60,160… … Angle measuring means 70,170 …… Tester moving means

Claims (1)

[Claims] 1. A front wheel turntable in which left and right front wheels are steerably supported, a rear wheel turntable in which left and right rear wheels are steerably supported, and before the steering angle of the front wheels is measured. In a four-wheel steering characteristic inspection device comprising a wheel turning angle measuring means and a rear wheel turning angle measuring means for measuring a turning angle of a rear wheel, one of the front and rear wheel turntables is rotatable and A full-float type turntable that is movable back and forth and left and right, and is provided with position detection means for detecting the front and back positions of wheels supported on the turntable, and at the position of the wheels detected by the position detection means. Accordingly, position adjusting means for performing front-rear position adjustment of the front wheel or rear wheel steering angle measuring means for measuring the steering angle of the wheel with respect to the wheel is provided. 4 wheel steering characteristic inspection device for vehicles.