JPH0737925B2 - 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.

(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 steered 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 steered from the lateral direction. Since force is applied, there is no phase shift from the steering wheel steering, and the posture of the vehicle can be kept almost on the tangent of the turning circle, and for example, lane changes during high-speed running 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.

(Problems to be Solved by the Invention) 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 respectively placed on rotatable turntables, and the steering wheel is operated. The front wheels are steered by the steering wheel, and the steering angle of the front wheels and the steering angle of the rear wheels that are steered according to the steering of the front wheels are measured to measure and inspect the steering characteristics of the rear wheels with respect to the front wheels. However, the tire of each wheel placed on the turntable is deformed due to the weight of the vehicle body, and this deformation becomes large due to the lateral load due to this turning when the wheel is turned,
There is a problem that a measurement error of the turning angle may occur. When the steering angle device is contacted with the side portion of the tire by a touch sensor that detects the steering angle of the wheel, the measured value of the touch sensor influences the deformation of the tire. There is a problem of receiving. Furthermore, the load on the turntable rotation support increases as the turntable receives all the weight of the vehicle body through the wheels.
There is a problem that the force required to rotate the turntable also increases.

(Means for Solving the Problems) The present invention provides an inspection device capable of reducing the load applied to the tire in view of the problem of the deformation of the tire mounted on the turntable due to the vehicle weight as described above. In order to solve the above problems, the inspection apparatus of the present invention is configured as follows as a means therefor. That is,
This device consists of a front wheel turntable in which the left and right front wheels are steerably supported, a rear wheel turntable in which the left and right rear wheels are steerably supported, and a front wheel turntable that measures the steered angle of the front wheels. Steering angle measuring means, rear wheel steering angle measuring means for measuring the turning angle of the rear wheels, and the vehicle body with the left and right front and rear wheels of the vehicle mounted on the front wheel turntable and the rear wheel turntable, respectively. It consists of a lifter that lifts,
The lifter lifts the vehicle body to reduce the ground contact force of the tires of the front and rear wheels.

(Operation) When the inspection device having the above-mentioned configuration is used, when the front and rear wheels are steered to inspect the four-wheel steering characteristics of the vehicle, the grounding force of the front and rear wheels to the turntable, that is, from the front and rear wheels Since the weight of the vehicle body applied to the turntable is light, the amount of deformation of the tires of the front and rear wheels is small, and the deformation of the tires during steering is also small. For this reason,
When the steering angle is measured by the touch sensor, the sensor is less affected by the deformation of the tire, and the error in the measured value is also small. Furthermore, since the load on the turntable is small, the force required to rotate the turntable is reduced, and the steering can be smoothly performed.

(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 for 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 rear. It is adapted to be steered by the 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 the characteristic inspection of the above-mentioned four-wheel steering system will be briefly described. To perform this characteristic inspection, first, the front wheels 1a, 1b and the rear wheels 2a, 2b are placed on rotatable turntables, respectively, and the vehicle body of this vehicle is lifted by a lifter. The lifting force of the lifter at this time is
It is necessary to ensure that each wheel does not separate from the turntable and that a sufficient grounding force can be secured to rotate the turntable as the wheels are steered, and that the load applied from the wheels to the turntable is as small as possible. desirable.
Thereafter, the steering wheel is operated to steer the front wheels, and at the same time, the steered angles of the front wheels 1a and 1b2 are measured.
When the front wheels 1a, 1b are steered in this manner, the front wheels 1a, 1b
The steering of 1b is transmitted to the rear wheel steering means 10 via the transmission bodies 5a, 5b connected by the connecting means 6, and the rear wheel steering means 10 is responsive to the steering amount of the front wheels 1a, 1b and the vehicle speed. Since the rear wheels 2a, 2b are steered, the steering angles of the rear wheels 2a, 2b at this time are also measured.
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 a knuckle arm that is steerably supported, and the rear wheels 2a, 2b are steered by moving the rear wheel steering rod 15 in the vehicle width direction. . This rear wheel steering rod 15 is a cylinder fixed to the vehicle body and automatically supporting the rear wheel steering rod 15 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. Is equipped with a spool valve 38b, which follows the movement of the spool valve 38b in the vehicle width direction and moves the valve housing 38a together with the rear wheel steering rod 15 in order to move the hydraulic chambers 13a, 13b of the hydraulic actuator. The hydraulic pressure 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 _two axes l ₁ and l ₂ and extends in a direction orthogonal to the rotation axis l ₂ and rotates the holder 21 around the support shaft 21a rotation axis l ₂ ). By rotating the support pin 22a at the tip end thereof and the moving axis l ₁ of the spool valve 38b, the swing locus surface of the swing arm 22 around the support pin 22a becomes the moving axis l _1. The angle of inclination with respect to a plane orthogonal to (hereinafter referred to as a reference plane) is changed.

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 joint 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 swung, and the axis of the pin 22a coincides with the moving axis l ₁ of the spool valve 38b, the ball joint 23a at the tip of the swing arm 22 only swings on the reference plane, and the spool valve 38b Is held stationary, but the axis of the pin 22a is inclined with respect to the movement axis l ₁ and the swing arm 2
If the rocking locus plane of 2 is displaced from the reference plane, this pin 22a
The ball joint 23a is displaced in the left-right direction in FIG. 3 in accordance with the swing of the swing arm 22 around the center of the swing arm 22, and this displacement is transmitted to the spool valve 38b via the connecting rod 24, and the spool valve 38b Move along the movement axis l ₁ . That is, even if the swing angle of the swing arm 22 about the axis of the support pin 22a is the same, the spool valve
The horizontal displacement of 38b is determined by the inclination angle of the pin 22a, that is, the holder.
It changes with the change of the rotation angle of 21.

Then, in order 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 shaft 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 27 composed of a potentiometer as a turning ratio detecting means for detecting the rotation angle of the sector gear 25a corresponding to the actual turning ratio controlled by the stepping motor 26. Is 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. The vehicle is transported in the direction of arrow A and the front and rear wheels are guided by the front wheel and rear wheel guides 43 and 47, respectively. It is designed to be positioned above the wheel static testers 41, 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.

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 full-float type turntable 50 that is mounted on a support base 41a and supports the front wheels so that they can be steered and move left and right and front and rear, and the tires of the front wheels placed on the turntable 50. Front wheel angle measuring means 60 for contacting the side surface to measure the toe-in angle, steered angle, etc. of the front wheels, and a tester moving means mounted on the support base 41a for moving the front wheel angle measuring means 60 in the vehicle width direction. Composed of 70 and. 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 tester moving means is provided.
By touching the measuring plate 61 to the side surface of the tire of the front wheel placed on the turntable 50 by the movement by 70 and measuring the inclination of the measuring plate 61 to measure the toe-in angle and the steering angle, It is configured.

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 ball 52a supports the table 53 so as to be rotatable and movable in the front, rear, left, and right directions. This table
Reference numeral 53 denotes a front wheel placed on and supported by the front wheel 53. Front and rear guides 53a, 53a for positioning the front wheel in the front-rear direction are provided, and the front wheel abuts on the inner surface of the front wheel in the width (left-right) direction. Left and right guide plates 53b for positioning
Is provided. Further, a rotary shaft 54 extending downward from the center thereof is attached to the table 53, and an encoder 55 for detecting a rotation angle of the table 53 is attached to a lower end of the rotary shaft 55. Table on frame 51 above
Conveyor plate to smoothly convey the front wheels to 53
51b and 51b are attached with the table 53 sandwiched in the front and back. Further, on the frame 51, shaft holding plates 56, 56 are disposed so as to face each other so as to sandwich the rotary layer 54 in the front and back and to be movable in the front and back. The shaft holding plates 56, 56 have a central portion 58a in the frame 51. Each of them is connected to an upper end of an arm 58 rotatably attached to the. The lower end 58c of the arm 58 is the cylinder 59
Are connected to both ends of the cylinder 59, and the arm 58 is rotated by the expansion and contraction of the cylinder 59 to move the shaft holding plate 56 back and forth.
6 approach each other and move away from each other when contracted. FIG. 8A is a cross-sectional view of the shaft holding plates 56, 56 and the rotary shaft 54 taken along arrows VIII-VIII, and as can be seen from this figure, the end portions of the shaft holding plates 56, 56 facing each other. Is provided with a notch 56a in the shape of a right triangle, and a portion 54a of the rotary shaft 54 facing the notch 56a has a square cross section in conformity with the notch. Therefore, the cylinder 59
When the shaft holding plates 56, 56 are extended and the shaft holding plates 56, 56 approach, the cuts 56a, 5
6a holds the square portion 54a and holds the rotating shaft 54 in a fixed manner. Therefore, in the above state, the table 53 also
53a is fixed and held with the front and rear facing.

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 joint 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 maintained when no external force acts on the measurement plate 61, and when the measurement plate 61 receives an external force, the springs 63a and 63b are bent and 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. A difference occurs in the amount of movement of the probe 64a in the front-back direction (the amount of movement in the displacement measuring device 64 in the front-back direction).
The steering angle, camber angle, etc. can be detected. Specifically, 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 the displacement measuring device 64 arranged on the left and right of the ball joint 62a, and the average value of both the movement amounts. The camber angle can be measured from the amount of movement of the displacement measuring device 64 arranged above the ball joint 62a. Therefore, if only the toe-in angle is adjusted and the steering angle is measured as in the present invention, the ball joint
Only two displacement measuring devices 64 arranged on the left and right sides of 62a may be used.
The displacement measuring device 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 fixed to 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 74 extending forward and backward between the guide rods 72, 72. Is 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 test 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 push 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 above limit is set on the frame 65 of the front wheel angle detecting means 60. A pair of switch plates 68, 68 facing the switch 73
Is attached to the switch plate 68 and limit switch.
When the limit switch 73 is actuated by the contact of 73, the motor
The drive control of 76 is performed so that 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 front wheel static tester 45 will be described next. Similarly to the front wheel static tester 41, the rear wheel static tester 45 is composed of a pair of left and right testers, and each tester is a full-float type turntable 150, a rear wheel angle measuring means 160 composed of a touch type sensor, and a tester moving means 170.
It consists of and. As shown in FIG. 13, the turntable 150 includes a frame 151, a plurality of bearings (not shown) attached to the frame 151, and a table 153 supported by the bearings so as to be rotatable and movable back and forth and left and right. Although these have a slightly different shape from the front wheel turntable 50, their functions and essential structures are the same, and therefore their explanations are omitted. on the other hand,
The rotation shaft 154 extending downward from the table 153 has a smaller downward extension amount than the rotation shaft 54 of the front wheel table 53, and the rotation of this shaft is detected only by the square cross section 154a at the lower end thereof. No encoder is installed. 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-rear angle measuring means 60 performs accurate measurement, and the encoder 55 is used to measure the angle exceeding the above range, but the steering angle of the rear wheels is ± in the straight direction. 5
This is because the angle is within the range of °, so that the rear wheel angle measuring means 160 alone can sufficiently perform the measurement. The rotary shaft 154
A pair of shaft holding plates 156, 156 are arranged so as to sandwich the square cross section 154a at the lower end of the front and rear, and both shaft holding plates 156, 156 are arranged.
Is normally pushed and spread by a spring 157, but the rotary shaft 154 is fixedly held by being pushed by the cylinders 158, 158 arranged in front and rear and being held by the shaft holding plates 156, 156 to hold the square section 154a. It is supposed to be done. 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 same as those of the front wheel static tester 41. Since the function and the essential structure are the same, the description thereof will be omitted.

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, the guide plates 91, 91 opened rearward in a "H" shape in order to correctly guide the front wheel to the guide groove 90a.
Is installed. Frames 96 and 97 facing the outer surface sides of both guide bodies 90 and 90 are attached with a rotatable first arm 92a and second arm 92b extending rightward in the figure, and both arms 92a and 92b. Are connected by a first connecting rod 93. The first arm 92a is connected to the guide body 90 supporting the right front wheel by the second connecting rod 95 as shown in the figure, and the second arm 92b is attached to the frame 97 facing the outer surface of the guide body 90 supporting the left front wheel. A third arm 92c extending forward (left side in the drawing) from the mounting portion of is attached to the second arm 92b so as to be rotatable together.
Is connected to a guide body 90 supporting the left front wheel by a third connecting rod 94 as shown. Therefore, if the first connecting rod 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. Even if the treads are different, both guide bodies should be fitted to this tread.
You can adjust the distance between 0 and 90.

Further, lifters 48 and 49 for raising and supporting the vehicle body are arranged in front of and behind the front wheel guide 43 (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 the front and rear wheels are placed on the full-float type turntable, when the 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 a horizontal external force 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, the cylinders 59, 158 and 158 of the front wheel turntable 50 and the rear wheel turntable 150 are extended to extend the shaft holding plates 56, 56 and 1
After the rotary shafts 54, 154 are fixedly held by 56, 156, the vehicle is transported onto the device 40 from the right side in the drawing in FIG. 5 in the direction of arrow A, and the front and rear wheel guides 43, 47 guide the front wheels 1a, 1b and the rear wheels. The wheels 2a and 2b are placed on the front and rear wheel static testers 41 and 45, respectively. Next, the head 101a of the lifters 48, 49 is moved upward to raise the side sill portion of the vehicle body by the head 10a to reduce the load from the front and rear wheels to the turntables 50, 150, and to hold the vehicle body in the horizontal direction of the vehicle body by an external force. To move to. 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. Next, the cylinders 59, 158, 158 of the front wheel turntable 50 and the rear wheel turntable 150 are contracted to release the fixed holding of the rotary shafts 54, 154 by the shaft holding plates 56, 56 and 156, 156, and the tables 53, 153 are 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, each toe-in measurement is performed by the angle measuring means 60 and 160 composed of the touch type sensors of the front and rear wheel static testers 41 and 45, and the toe-in is performed 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. 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 (they are steered in the same phase). The steering angle gradually decreases 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, the desired basic characteristics are set in advance for each of the special 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 steering wheel 3 is reciprocated leftward and rightward about its horizontal direction, and the front wheels 1a, 1b are steered back and forth within a certain range centered on its straight traveling 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 replaced with a vehicle speed sensor of the vehicle to be inspected and connected to the controller 33, and a 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 and rear wheels when the front wheels are steered by operating the steering wheel under the above conditions is determined 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 the vertical axis representing the rear wheel steering angle and the horizontal axis representing the front wheel steering angle, 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 based on the steering of either the right or left direction of the front wheels. Since the steered angle of the rear wheels is deviated to impair the running stability, in the present invention, in the comparative inspection means 100 which receives the 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.

(Effects of the Invention) As described above, according to the present invention, a front wheel turntable in which left and right front wheels are steerably supported and a rear wheel turntable in which left and right rear wheels are steerably supported, respectively. The table, the front wheel turning angle measurement position for measuring the front wheel turning angle, the rear wheel turning angle measuring means for measuring the rear wheel turning angle, and the front and rear turntables for the left and right wheels of the vehicle. The front and rear wheels of the vehicle have lifters for lifting the vehicle body, and the lifter raises the vehicle body to reduce the ground contact force of the tires of the front and rear wheels. When the front and rear wheels are steered to inspect the characteristics, the grounding force of the front and rear wheels to the turntable, that is, the weight of the vehicle body applied to the turntable from the front and rear wheels is reduced, and The amount of deformation of the tires of the rear wheels is small, and the deformation of the tires during steering is also small. Therefore, this sensor is less likely to be affected by the deformation of the tire when the steering angle is measured by the touch sensor, and the error in the measured value is also small.
Furthermore, since the load on the turntable is small, the force required to rotate the turntable is reduced, and the steering can be smoothly performed.

[Brief description of drawings]

FIG. 1 is a plan view schematically showing a four-wheel steering system of a vehicle, FIG. 2 is a plan schematic view of the above-mentioned four-wheel steering value, and FIG. 3 is a perspective schematic view showing a turning ratio variable mechanism, FIG. 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 A front sectional view and a side view showing a turntable for the front wheels, FIG. 8A is a sectional view showing the turntable along the arrow VIII-VIII, and FIGS. 10 to 12 show front wheel angle measuring means and tester moving means. Front view, plan view and side view, FIG. 13 is a front view showing a rear wheel turntable, FIG. 14 is a front 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 measurement results of changes in the rear-wheel steering angle with respect to the front-wheel steering. . 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 device for inspecting the four-wheel steering characteristics of a vehicle having a four-wheel steering device adapted to steer the rear wheels according to the turning of the front wheels, wherein the left and right front wheels are supported so that they can be steered freely. The front-wheel turntable, the rear-wheel turntable in which the left and right rear wheels are steerably supported, the front-wheel turning angle measuring means for measuring the front-wheel turning angle, and the rear-wheel turning angle The rear wheel turning angle measuring means for measuring, and a lifter for lifting the vehicle body of the vehicle while the left and right front and rear wheels of the vehicle are respectively placed on the front wheel turntable and the rear wheel turntable,
A four-wheel steering characteristic inspection device for a vehicle, characterized in that the grounding force of the tires of the front and rear wheels is reduced by lifting the vehicle body by the lifter.