JPS63201550A - Inspecting device for four-wheel steering characteristic of vehicle - Google Patents

Abstract

PURPOSE:To accurately and speedily measure variation characteristics of the steering angle of the rear wheels to the steering of the front wheels by mounting the front and rear wheels on a full-float type turntable, and smoothing their steering. CONSTITUTION:The wheels are carried onto device 40 as shown by A to mount the front wheels 1a and 1b, and rear wheels 2a and 2b on front-wheel and rear-wheel static testers 41 and 45. The heads of lifters 48 and 49 are moved up to elevate sole bar parts of the vehicle body, thereby reducing the load from the front and rear wheels to turntables 50 and 150 and also preventing the vehicle body from moving horizontally. Then the cylinders of the front-wheel and rear-wheel turntables 50 and 150 are contracted to release a rotary shaft from being held and fixed by a shaft holding plate and also places the table 53 in a full-float state. In this state, angle measuring means 6 and 160 consisting of touch sensor of front-wheel and rear-wheel static testers 41 and 45 measure toe-in angles, which are adjusted to specific values.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention enables the rear wheels to be steered in response to the front wheels being steered by operating the steering wheel4.
The present invention relates to a vehicle having a wheel steering device, and more particularly to a device for inspecting the characteristics of this four-wheel steering device.

(Prior technology) Conventionally, four-wheeled vehicles were typically steered by steering only the front wheels using the steering wheel, but steering only the front wheels could cause the rear wheels to skid depending on the driving situation, or the turning radius Problems have been pointed out in terms of maneuverability and steering, such as the limited ability to make small turns, and in light of this, a four-wheel steering system that steers the rear wheels as well as the front wheels has recently been proposed and researched. There is.

In other words, with a four-wheel steering system, when driving at relatively high speeds, if the rear wheels are steered in the same direction as the front wheels (this is called in-phase steering), lateral forces are applied to the front and rear wheels at the same time. Since this is added, there is no phase lag from the steering wheel steering, and the vehicle's attitude can be maintained almost on the tangent to the turning circle, allowing smooth lane changes, for example, when driving at high speeds. Also, if the rear wheels are steered in the opposite direction to the front wheels when driving at very low speeds (this is called reverse phase steering), the direction of the vehicle can be changed significantly, which is convenient for parallel parking or parking in a garage.

Furthermore, considering that the front wheels are not steered significantly at relatively high speeds, and the front wheels are steered significantly when driving at relatively low speeds, the rear wheels are also steered within the range where the front wheels are steered small. It can be seen that a four-wheel steering system is required that steers the rear wheels in the same direction and steers the rear wheels in the opposite direction when turning a large amount.

For this reason, we have provided a mechanism that can arbitrarily variably control the ratio of the steering angle of the rear wheels to the steering angle of the front wheels, that is, the steering ratio, and adjust the steering ratio according to vehicle speed, front wheel steering angle, etc. Variable control! It has been proposed to improve Im-ability and driving stability. For example, as disclosed in Japanese Unexamined Patent Publication No. 61-108070, there is a four-wheel steering system that variably controls the steering phase and steering ratio depending on the vehicle speed.

In conventional vehicles that steer only two wheels, the front wheels are steered proportionally to the operation of the steering wheel, so it was only necessary to adjust the horizontal position of the steering wheel and the straight direction of the front wheels. In a steering system, the front wheels are steered proportionally in response to steering wheel operations, but the rear wheels are steered based on steering characteristics determined by the front wheel steering angle and vehicle speed. However, with only the conventional adjustment, there is insufficient inspection of the steering characteristics of the rear wheels relative to the front wheels, and there is a problem in that the driving stability of the vehicle cannot be sufficiently guaranteed if left as is. Therefore, the present applicant can measure the steering angles of the front wheels and the rear wheels to inspect the steering characteristics of the rear wheels relative to the steering of the front wheels, that is, the steering characteristics of the four-wheel steering system. This paper proposes an inspection device and method.

(Problem to be Solved by the Invention) In this case, in order to measure the steering angles of the front wheels and rear wheels, the front wheels and the rear wheels are respectively placed on rotatable turntables, and the steering wheel is operated. The steering angle of the front wheels and the steering angle of the rear wheels that are steered in accordance with the steering of the front wheels are measured to measure and inspect the steering characteristics of the rear wheels relative to the front wheels. However, in order to smoothly steer the wheels placed on the turntable, a full-float type turntable is often used, which is rotatable and movable back and forth and left and right. . In this case, the steering of the front and rear wheels is smooth and it is easy to measure their steering angles, but if a lateral external force is accidentally applied to the vehicle, the vehicle body will move in the direction of this external force. There is a problem in that the vehicle body is easily moved, and the measurement of the steering angle becomes incorrect due to this movement of the vehicle body. In addition, conventional two-wheel steering vehicles also suffer from problems similar to the above, such as lateral movement of the vehicle during testing using a roller-type automobile testing machine and horizontal movement of the vehicle during testing using a toe-in testing machine. In response to these problems,
- Preventing the movement of the vehicle by clamping the skirts on both sides of the vehicle body as disclosed in Publication No. 47682, or by clamping the bumper of the vehicle body as disclosed in Publication No. 58-56964. It is made to be.

(Means for Solving the Problems) The present invention provides for horizontal movement of a vehicle when inspecting the steering characteristics of a four-wheel steering system with the front and rear wheels placed on the full-float turntable as described above. In view of the problem of the influence of In addition, there is a full-float type front wheel turntable that is supported so as to be movable back and forth, and a full-float type rear wheel turntable that is supported so that the left and right rear wheels are steerable and movable back and forth. It has a front wheel steering angle measuring means for measuring the steering angle and a rear wheel steering angle measuring means for measuring the steering angle of the rear wheels. The vehicle body fixing means is provided to fix and hold the vehicle body in a state in which each wheel is supported and prevent the vehicle body from moving even when a lateral external force is applied to the vehicle body.

(Function) When using the above-configured inspection device, the front and rear wheels are placed on a full-float turntable that can be steered and moved forward, backward, left, and right, so both the front and rear wheels can be steered smoothly. This not only makes it possible to accurately and quickly measure the changing characteristics of the rear wheel turning angle relative to the front wheel turning, but also allows the vehicle body fixing means to hold the vehicle body even when a horizontal external force is applied to the vehicle. Since the movement of the vehicle body is prevented, the vehicle body does not move due to this external force, and the steering angle can be measured accurately.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described based on 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 a front wheel steering means 4 according to the operation of a steering wheel 3, and rear wheels 2a and 2b are steered by a front wheel steering means 4 in accordance with the operation of a steering wheel 3.
is steered by rear wheel steering means 10. The steering amount of the front wheel steering means 4 is transmitted to the rear wheel steering means 10 via transmission bodies 5a and 5b, and the steering phase and steering ratio are adjusted according to this steering amount, vehicle speed, etc. variable controlled,
Based on these steering phases and steering ratios, the rear wheels 2a and 2b are controlled to be steered by the rear wheel steering means 10, so that four-wheel steering is performed. Note that the transmitting bodies 5a, 5b are connected via a connecting means 6, but the transmitting bodies 5a, 5b are
b may be a shaft that mechanically transmits the steering of the front wheels la, Ib to the rear wheel steering means 10;
It may be something like a cable for transmitting the steering of Ib as an electrical signal.

First, a method for testing the characteristics of the four-wheel steering system will be briefly described. To perform this characteristic test, first, the front wheels 1a, 1b and the rear wheels 2a, 2b are placed on a full-float turntable that is rotatable and movable back and forth and left and right, and the body of the vehicle is fixed to the body. Fixed and held by means. Thereafter, the steering wheel is operated to turn the front wheels, and at the same time, the turning angles of the front wheels 1a and 1b2 are measured. 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 coupling means 6, and The steering means 10 steers the rear wheels 2a according to the steering m of the front wheels 1a, Ib, the vehicle speed, etc.
, 2b, the steering angles of the rear wheels 2a and 2b at this time are also measured. Based on these measurements, front wheel 1
The change characteristics of the turning angles of rear wheels 2a and 2b with respect to the turning angles of wheels a and 1b are detected, and this characteristic is compared and contrasted with a preset basic characteristic to determine whether or not it matches this basic characteristic. inspect. Note that if the above-mentioned measured characteristics do not match the basic characteristics, the four-wheel steering system is adjusted so that the desired characteristics are obtained.

Generally speaking, characteristic tests are carried out as described above, but below we will show a specific example of a four-wheel steering system, as well as a detailed explanation of toe-in adjustment of the front and rear wheels of a vehicle equipped with this system and a characteristic test of this system. A method and apparatus for this purpose will be described.

FIG. 2 is a schematic plan view showing an example of a four-wheel steering device.

The front wheel steering means 4 includes a front wheel steering rod 4a having a first rack that engages with a first rack formed at the lower end of the steering wheel 3, and tie rods 4b, 4b connected to both ends of the rod 4a. , tie rod 4b, 4b
knuckles 4C, 4c connected to the outer ends of the front wheel steering rods 4 and 4c.
a is moved in the vehicle width direction, and this movement causes the tie rod 4b,
4b to the knuckles 4C, 4c, and the front wheels 1a,
1b is steered. Further, the front wheel steering rod 4a is provided with a second shaft provided at the front end of the rotation transmission shaft (transmission body) 5a
A second rack is formed with which the binion 5C engages,
The front wheel steering rod 4 is controlled by operating the steering wheel 3.
When a is moved in the vehicle width direction, the second and union 5C are moved at the same time.
The rotation transmission shaft 5a is rotated via. This rotation is transmitted to the variable steering ratio mechanism 20 of the rear wheel steering means 10 via the coupling means 6 and the other transmission shaft 5b,
The rear wheels are steered as described below in accordance with the steering phase and steering ratio adjusted here.

On the other hand, the rear wheel steering means 10 includes a rear wheel steering rod 15 extending in the vehicle width direction, a tie rod 16.16 connected to both ends of the rod 15, and a tie rod 16.1.
a rear wheel 2a having a knuckle arm connected to the outer end of the rear wheel 2a;
The knuckles 11 and 17 support the rear wheels 2b in a steerable manner, and the movement of the rear wheel steering rod 15 in the width direction of the vehicle steers the rear wheels 2b.
A and 2b are steered. The rear wheel steering rod 15 includes a cylinder 11 that is fixed to the vehicle body and supports the rear wheel steering rod 15 so as to be movable in the vehicle width direction, and a cylinder 11 that divides the inner space of the cylinder 11 into two.
A piston 12 is fixedly attached to the cylinder 5 and is slidable inside the cylinder 11.
and a neutral return spring 14a disposed within the left and right hydraulic chambers 13a, 13b divided by the piston 12.
, 14b is attached. The left and right hydraulic pressure of this hydraulic actuator 'J13a,
13b is the hydraulic line 3 from the control valve 38.
9a and 39b are connected, and the control valve 3
The hydraulic actuator is actuated by the hydraulic pressure supplied from B, and the rear wheel steering rod 15 is moved in the vehicle width direction, thereby steering the rear wheels. Note that the hydraulic oil in the tank 35 is pressurized by a pump 36 and supplied to the control valve 38 . This control valve 38 is constructed of a known spool valve type, and includes a cylindrical valve housing 38a that is integrally connected to the rear wheel steering rod 15 via an arm 15a, and a cylindrical valve housing 38a that is fitted into the valve housing 38a. The hydraulic chamber 13a of the hydraulic actuator is configured to move the valve housing 38a together with the rear wheel steering rod 15 following the movement of the spool valve 38b in the vehicle width direction. , 13b are selectively supplied with hydraulic pressure. That is, by moving the spool valve 38b in the vehicle width direction, the rear wheel steering rod 15 is moved following the spool valve 38b, and the rear wheels are steered.

The hydraulic lines 39a and 39b are connected to a normally closed fail-safe solenoid valve 37 via hydraulic lines 37a and 37b, respectively.
When opened, both hydraulic chambers 13 of the hydraulic actuator
The oil pressures in a and 13b become equal, and the neutral return spring 14a
, 14b causes the piston 12 to be positioned at the neutral position, and a fail-safe mechanism is activated in which the steering angle of the rear wheels 2a and 2b is always zero, and the steering characteristics of the vehicle are in a two-wheel steering state. There is.

The movement of the spool valve 38b in the vehicle width direction is caused by the variable steering ratio tfi1 receiving rotation from the rotation transmission shaft 5b.
This variable steering ratio mechanism 20 will be explained with reference to FIG. 3. This variable steering ratio mechanism 20 has a base end attached to a U-shaped holder 21 and a support bin 22a.
A swing arm 22 is swingably supported through the swing arm 22,
The holder 21 is rotatably supported by a casing (not shown) fixed to the vehicle body via a support shaft 21a having a rotation axis 9Jz perpendicular to the movement axis z1 of the spool valve 38b. The support bin 22a of the swing arm 22 is located at the intersection of both axes of 1.9Jz and extends in a direction perpendicular to the rotation wheel refill 2, and rotates the holder 21 around the rotation axis 9, 2) of the support shaft 21a. By rotating the support bottle 22a at the tip and the movement axis 9 of the spool valve 38b,
．． s, that is, the swinging locus plane of the swinging arm 22 centered on the support bin 22a is the movement axis 9. The angle of inclination made with respect to a plane perpendicular to x (hereinafter referred to as a reference plane) is changed.

Further, one end of a connecting rod 23 is connected to the tip of the swing arm 22 via a ball joint 23a, and the other end of the connecting rod 23 is connected to a spool valve 38b and the like via a ball joint 23b. The spool valve 38b is connected to the end thereof, and is adapted to displace the spool valve 38b in the left-right direction in accordance with the displacement of the tip end of the swing arm 22 in the left-right direction in FIG. 3 as the swing arm 22 swings.

The connecting rod 23 has its ball joint 2
It is slidably supported by the rotation imparting arm 24 via a ball joint 230 at a portion close to 3a. The rotation imparting arm 24 is comprised of a large diameter bevel gear rotatably supported on the moving shaft l119Jl via a support shaft 24a, and the bevel gear is attached to a bevel gear attached to the rear end of the rotation transmission shaft 5b. 5d are engaged 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 around the movement axis by an amount corresponding to the rotation angle of the spooling wheel 3, and accordingly, the swing arm 22 rotates around the support pin 22a. When the pin 22a is swung, when the axis of the pin 22a coincides with the movement axis 9, 1 of the spool pulp 38b, the swiveling arm 2
The pole joint 23a at the 2nd tip only swings on the reference plane, and the spool pulp 38b is held stationary, but the axis of the bin 22a is inclined with respect to the movement axis 9Jl and the swinging trajectory of the swinging arm 22 is changed. If the surface deviates from the reference plane,
As the swing arm 22 swings about the pin 22a, the ball joint 23a is displaced in the left-right direction in FIG. 3, and this displacement is transmitted to the spool pulp 38b via the connecting rod 24. Spool pulp 38
b moves along the movement axis 9J1. That is, even if the swing angle of the swing arm 22 about the axis of the support bin 22a is the same, the displacement of the spool pulp 38b in the left-right direction is due to the change in the tilt angle of the bin 22a, that is, the rotation angle of the holder 21. It changes accordingly.

In order to change the rotation angle of this holder 21,
A sector gear 25a as a worm wheel is attached to the support shaft 21a of the holder 21.
A worm gear 25b is meshed with a. A bevel gear 25C is installed on the shaft of this worm gear 25b,
A bevel gear 25d mounted on the output shaft of a stepping motor 26 as an actuator is meshed with this bevel gear 25c, and by operating the stepping motor 26 and rotating the sector gear 25a, The tilt angle is changed to control the steering angle of the rear wheels 2a, 2b, that is, the steering ratio and steering phase of the front and rear wheels 1a, 1b, 2a, 2b. Further, on the support shaft 21a of the holder 21, a steering ratio sensor consisting of a potentiometer is provided as a steering ratio detection means for detecting the rotation angle of the sector gear 25a corresponding to the actual steering ratio controlled by the stepping motor 26. 27 are provided.

Control of the steering ratio and steering phase by the stepping motor 26 is performed by a controller 33 that receives a vehicle speed signal from a vehicle speed sensor 34 and receives power from a battery 31. For example, as shown in FIG. 4, when the vehicle speed is zero, With the opposite phase, the steering ratio becomes maximum and the vehicle speed reaches 307/H.
When , two-wheel steering is in the zero phase state, and the vehicle speed is 120/
The steering ratio is maximized with the same phase at 1 m/H.

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

FIG. 5 is a plan view showing an inspection device 14G for toe-in adjustment and four-wheel steering characteristic inspection, and this device 40
includes a front wheel static tester 41 that measures the toe-in angle, steering angle, etc. of the front wheels, a front wheel guide 43 that guides the left and right front wheels to the front wheel static tester 41, and a front wheel guide 43 that measures the toe-in angle, steering angle, etc. of the rear wheels. As shown in the figure, a rear wheel static tester 45 and a rear wheel guide 41 for guiding the left and right rear wheels to the rear wheel static tester 45 are arranged in a line as shown in the figure. The front and rear wheels are conveyed and guided by the front and rear wheel guides 43 and 47, respectively, to the front and rear wheel static tester 41.
．． 45. Note that this device 40 includes a signal sending means 105 for sending a vehicle speed signal etc. to the vehicle to be inspected, and a comparison testing means 100 for comparing the four-wheel steering characteristics measured by the device 40 with preset basic characteristics. have.

For this reason, lines 100a to 100d into which the measured values of the steering angles of the front and rear wheels are input are connected to the comparison inspection means 100.
A line 105a having a connector 105b connected to a vehicle controller is connected to the signal sending means 105.

FIG. 6 is a front view showing the front wheel static tester 41 in detail along the arrow Vl-Vl, and FIG. 7 is a detailed plan view of the static tester 41.

As can be seen from the figure, this static tester 41 consists of a pair of testers that are symmetrical on the left and right in order to measure the toe-in angle and steering angle of the left and right front wheels. are given the same number and only one will be explained. The static tester 41 includes a full-float turntable 50 that is mounted on a support stand 41a and supports the front wheels so that they can be steered and moved left and right and back and forth, and the tires of the front wheels that are placed on the turntable 50. a front wheel angle measuring means 60 that measures the toe-in angle, steering angle, etc. of the front wheels by coming into contact with the side surface; and the support stand 4.
The tester moving means 70 is mounted on the front wheel angle measuring means 1a and moves the front wheel angle measuring means 60 in the vehicle width direction. This front wheel angle measuring means 60 has a measuring plate 61 that comes into contact with the tire side surface of the front wheel, and is moved by the tester moving means 70 to bring the measuring plate 61 into contact with the side surface of the front wheel tire placed on the turntable 50. It also includes a touch sensor that measures the inclination of this measuring plate 61 to measure the toe-in angle and steering angle.

Here, the turntable 50 is shown in detail in FIGS. 8 and 9, and the structure of the turntable 50 will be described. This turntable 50 has a frame 51 made up of a plurality of members fixed to a support base 41a, and a plurality of bearings 52 are fixedly arranged on the upper surface of this frame 51 in line on the same circumference. The bearing 52 has a rotatable ball 52a, and the table 53 is supported by the ball 52a so as to be rotatable and movable back and forth and left and right. This table 53 supports the front wheel by placing it thereon, and is provided with front and rear guides 53a, 53a for positioning the front wheel in the front and rear direction.
Left and right guide plates 53b are provided that abut against the inner surface of the front wheel to position the front wheel in the width (left and right) direction.

Further, a rotating shaft 54 extending downward from the center of the table 53 is attached to the table 53, and an encoder 55 for detecting the rotation angle of the table 53 is attached to the lower end of the rotating shaft 55. The frame 51 has a transport plate 51 for smoothly transporting the front wheels to the table 53.
b, 51b are attached with the table 53 sandwiched between the front and back. Furthermore, a shaft holding plate 5 is provided on the frame 51, facing the rotating shaft 54 so as to sandwich it in the front and back, and also movable back and forth.
6.56 are disposed, and the center portion 58a of each shaft holding plate 56.56 is connected to the upper end of an arm 58 rotatably attached to the frame 51, respectively. Arm 5
The lower end 58c of the cylinder 59 is connected to both ends of the cylinder 59, and as the cylinder 59 expands and contracts, the arm 58 is rotated and the shaft holding plate 56 is moved back and forth. The two wheel retaining plates 56,56 move toward each other and move away from each other when retracted. FIG. 8A shows a cross section of the two wheel holding plates 56, 56 and the rotating shaft 54 along the arrows ■-■, and as can be seen from this figure,
A notch 56a in the shape of a right triangle is provided at the mutually opposing ends of the shaft holding plates 56,56, and a portion 54a of the rotating shaft 54 facing this notch 56a has a square cross section matching the above notch. ing.

Therefore, the cylinder 59 is extended and the both wheel holding plates 5
6.58, the notches 56a, 56a clamp the square portion 54a and hold the rotating shaft 54 fixedly.

Therefore, in the above state, the table 53 also
It is fixed and held in a state where a is facing forward and backward.

Next, the structures of the front wheel angle measuring means 60 and the tester moving means 70 will be explained using FIGS. 10 to 12. The front wheel angle measuring means 60, which is a touch type sensor, extends forward to a frame 65 and has a support shaft 62 attached thereto, and a measuring plate 61 is rotatably attached to the front end of the support shaft 62 via a ball joint 62a. ing. In this state, the measuring plate 61 is rotatable about the ball joint 62a, but is held vertically upright with respect to the frame 65 by the compression spring 63a1, the tension spring 63b, and the link 63c as shown in the figure. Note that the measuring plate 61 is held in an upright state when no external force acts on the measuring plate 61, and when the measuring plate 61 receives an external force, the spring 6
The measurement plate 61 is rotated around the ball joint 62a in response to external force due to the deflection of the links 3a and 63b and the deformation of the link 63c. Therefore, when the measuring plate 61 is brought into contact with the side surface of the tire of the front wheel, the measuring plate 61 will be tilted according to the inclination of the tire, so if the inclination of this measuring plate is measured, the toe-in angle of the front wheel and the steering angle can be determined. , camber angle, etc. can be measured. In order to measure the inclination angle of this measuring plate 61, three displacement measuring devices 64 are attached to the frame 65. This displacement measuring device 64 has a probe 64a that protrudes forward and is movable back and forth.
As shown in the figure, they are attached to the left, right, and above the ball joint 62a. This probe pro 48 is adapted to abut against an abutting seat 61a fixed to the measuring plate 61 when the measuring plate 61 abuts against the side surface of the tire.
When the measuring plate 61 is tilted, there will be a difference in the longitudinal movement M (the amount of longitudinal movement within the displacement measuring device 64) of each probe 64a, and this difference will determine the toe-in angle, steering angle, and camber angle. etc. can be detected.

Specifically, the toe-in angle and the steering angle can be measured from the difference in the amount of movement of the probes 64a of the displacement measuring instruments 64 arranged on the left and right sides of the ball joint 62a, and the average value of both the amounts of movement can be measured. The camber angle can be measured from the amount of movement of the displacement measuring device 64 disposed above the ball joint 62a. Therefore, if only the adjustment of the toe-in angle and the measurement of the steering angle are performed as in the present invention, only the two displacement measuring instruments 64 disposed on the left and right sides of the ball joint 62a are sufficient. Note that these displacement measuring devices 64 and the like are covered with a cover 60a as shown by the two-dot chain 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 freely movable in the front and rear direction. explain. The tester moving means 70 has a frame 71 fixed on the support base 41a, and a pair of left and right guide rods 72, 72 extending back and forth by the frame 71, and a transport rod extending back and forth between these guide rods 72, 72. 74 is supported.

On each guide rod 72 are 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 into each other, so that the front wheel angle measuring means 60 is supported by the tester moving means 70 so as to be movable back and forth. Further, the transport rod 74 is threaded on its outer periphery, and a threaded bush 66a of the transport leg 66 fixed to the lower surface of the frame 65 of the front wheel angle measuring means 60 is threadedly engaged with the transport rod 74. . The transport rod 74 is rotatably supported by the frame 71 and has a first sprocket 75 attached to its end.
a is engaged with a second sprocket 75c mounted on the shaft of a motor 76 via a chain 75b, and by rotationally driving the motor 76 and rotating the transport rod 74, the front wheel angle is adjusted via the transport legs 66. The entire measuring means 60 can be moved back and forth. In order to set the forward and backward movement position at this time, the frame 71 of the tester moving means 70
There are two limit switches 73.7 separated in the front and back direction.
3 is attached to the frame 65 of the front wheel angle detection means 60, and a pair of switch plates 68, 68 facing the limit switch 13 are attached to the frame 65 of the front wheel angle detection means 60. The drive control of the motor 76 is performed by the operation of the front wheel angle detecting means 60, and the forward and backward movement position of the front wheel angle detecting means 60 is determined.

Although the front wheel static tester 41 has been described above, the rear wheel static tester 45 will now be described. Similar to the front wheel static tester 41, the rear wheel static tester 45 also consists of a pair of left and right testers, and each tester includes a full float type turntable 150, a rear wheel angle measuring means 160 consisting of a touch sensor, and a tester moving means 170. It is composed of. As shown in FIG. 13, the turntable 150 includes a frame 151,
It has a plurality of bearings (not shown) attached to a 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 their shapes are different, their functions and essential structures are the same, so their explanations will be omitted. On the other hand, the rotary shaft 154 extending downward from the table 153 has fewer openings for downward extension than the rotary shaft 54 of the table 53 for the front wheels, and only has a square cross section 154a at its lower end, which allows rotation of this shaft. No encoder is installed to detect this. This is because the steering angle of the front wheels in a four-wheel steered vehicle is large, so the front wheel angle measuring means 60 alone cannot measure the steering angle. is measured with high accuracy by the front wheel angle measuring means 60, and angles exceeding the above range are measured by the encoder 55. However, the steering angle of the rear wheels is ± around the straight direction. This is because the rear wheel angle can be sufficiently measured only by the rear wheel angle measuring means 160 since it is within the range of 5°. Note that the rotating 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 in the front and rear. Both wheel retaining plates 156, 15 are pushed by each cylinder 158, 158
The rotation shaft 154 is held fixed by the square cross-sectional portion 154a being held between the two members 6.

The rear wheel angle measuring means 160 for measuring the toe-in angle, steering 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 (horizontal direction) are different from those of the front wheel static tester 41. Since the functions and essential structures are the same, their explanation will be omitted.

Next, the front wheel guide 43 and rear wheel guide 47 that guide the front wheel and the rear wheel to the front wheel static tester 41 and the rear wheel static tester 45, respectively, will be explained. 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. This front wheel guide 43 connects the left and right front wheels to static testers 41, respectively.
It has a pair of guide bodies 90, 90 each having a guide groove 90a for guiding the guide bodies 90, 90.
is movable in the vehicle width direction (left/right direction). In addition, guide plates 91.91 that open toward the rear in a "V" shape are attached to correctly guide the front wheels to the guide groove 90a. A first arm 92a and a second arm 92b which extend to the right in the figure and are rotatable are attached to frames 96 and 97 facing the outer surfaces of both guide bodies 90 and 90, and both arms 92a and 92b. are connected by a first connecting rod 93. Further, as shown in the figure, the first arm 92a is connected to a guide body 90 km that supports the right front wheel by a second connecting rod 95, and the second arm 92b is connected to a frame 97 that faces the outer surface of the guide body 90 that supports the left front wheel. The third arm 92 that extends forward (to the left in the figure) from the
The third arm 92C is connected to a guide body 90 supporting the left front wheel by a third connecting rod 94, as shown in the figure. Therefore, by moving the first connecting rod 93 in the vehicle width direction using a cylinder (not shown) or the like, both guide bodies 90 and 90 can be moved in opposite directions in the vehicle width direction, thereby allowing the front wheel Even if the treads of the two guide bodies 90 and 90 are different, the distance between the guide bodies 90 and 90 can be adjusted according to the treads.

Further, lids 48 and 49 for lifting and supporting the vehicle body are provided before and after the front wheel guide 43 (see FIG. 5). As shown in FIG. 15, which shows a cross section taken along the arrow xv-xv in FIG. The rod 101 can freely protrude upward, and the head 1 has a groove 101b at its upper end.
01a is installed.

Therefore, when the zero end 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 full-float turntables, if an external force is applied to the car body in the horizontal direction, the turntables will be moved and the car body will be pushed, causing inaccurate measurements by the front and rear wheel angle measuring means. However, by lifting and supporting the vehicle body using 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 vehicle body mth applied to the tires placed on the turntable can be reduced. This reduces the deformation of the tire, and when measuring the turning angle using the touch sensor, this sensor is less affected by the deformation of the tire, so the error in the measured value is also reduced. The load on the turntable is reduced, allowing the turntable to rotate smoothly.

A second method for testing the four-wheel steering characteristics of a vehicle equipped with a four-wheel steering device using the testing device 40 as described above.
The explanation will be given by taking the four-wheel steering vehicle shown in the figure as an example. first,
Front wheel turntable 50 and rear wheel turntable 15
The rotating shaft 54 is extended by the shaft holding plates 56, 56 and 156, 156.
, 154, the vehicle is conveyed onto this device 40 in the six directions of arrows from the right side of the figure in FIG.
Front wheels 1a, 1 by front wheel and rear wheel guides 43.47
b and rear wheels 2a and 2b are placed on front and rear wheel static testers 41 and 45, respectively. Next, the heads 101a of the lifters 48 and 49 are moved upward, and the side sills of the vehicle body are lifted by the heads 101a.
The load on the turntables 50, 150 from the front and rear wheels is reduced, and the vehicle body is held to prevent horizontal movement of the vehicle body due to external force.

The lifting force of the vehicle body by the lifters 48, 49 is set so that a load sufficient to allow the tables 53, 153 to rotate smoothly in response to steering of the front wheels and rear wheels is left on the tables 53, 153. Next, the front wheel turntable 5
0 and each cylinder 59 of the rear wheel turntable 150,
158, 158 are contracted to release the fixed holding of the rotating shaft 54.154 by the shaft holding plates 56.56 and 156.156, and the table 53.153 is brought into a fully floating state.

From this state, toe-in adjustment of the front wheels and rear wheels is first performed. This toe-in adjustment is performed separately for the front and rear wheels with the front and rear wheel steering means 4.10 disconnected from the connection means 6. In this case, the toe-in angle is measured by the angle measuring means 60, 160 consisting of touch sensors of the front and rear wheel static testers 41, 45, with the front and rear wheels facing straight ahead and the steering wheel facing horizontally. The toe-in angle is adjusted to a predetermined value, and then the front wheel and rear wheel steering means are connected by the connecting means 6, but a detailed explanation of the adjustment method will be omitted.

Note that the toe-in adjustment herein includes not only so-called toe-in adjustment of the wheels but also adjustment in the toe-out direction.

After the toe-in adjustment described above, the four-wheel steering characteristics are inspected. Adjustment of this four-wheel steering characteristic is based on the steering angles of the front wheels ia and ib and the rear wheels 2a and 2a,
2b to measure and inspect the relationship with the steering angle,
The specific inspection method will be explained below.

First, a simulated vehicle speed signal (for example, vehicle speed 1201
f! A vehicle speed signal corresponding to R/H is sent out. When the front wheels 1a and 1b are steered by operating the steering wheel 3 in this state, the rear wheels 2a and 2b are also steered in the same phase, so the front and rear wheel static tester 41 measures the steering angles of these front and rear wheels. , 45. The graph in FIG. 16 shows an example of the relationship between the front wheel turning angle and the rear wheel turning angle measured in this manner. 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 shows the steering of the rear wheels and front wheels to the right. There is. As you can see from this graph, when the front wheels are steered to the right, the rear wheels are also steered to the right (steered in the same phase), and this change in the steering angle of the rear wheels gradually decreases, and steering is not performed at a predetermined steering angle (maximum right steering angle) of 01 or more. The same is true when the front wheels are steered to the left, and the rear wheels are in the same phase and the maximum left steering angle θ2
The steering wheel is steered while gradually reducing the change until the end.

Next, a simulated vehicle speed signal (for example, a vehicle speed signal corresponding to vehicle speed 30b/H) that sets the steering phase to zero phase is transmitted from the signal transmitting means 105 to the controller 33 via the line 105a. Even if the front wheels 1a, 1b are steered by operating the steering wheel 3 in this state, the rear wheels 2a, 2b
should be held at zero phase and not steered. The steering angles of these front and rear wheels are measured by front wheel and rear wheel static testers 41 and 45, and the 17th example shows an example of the relationship between the front wheel steering angle and the rear wheel steering angle measured in this way. This is a graph of the figure. As you can see from this graph,
When the front wheels are steered to the right, the rear wheels are hardly steered;
Extremely small steering angle θ1 due to dimensional errors, etc. Only θ2 occurs.

Further, a simulated vehicle speed signal (for example, a vehicle speed of 0 KI,
A vehicle speed signal corresponding to R/H is sent out.

In this state, operate the steering wheel 3 to rotate the front wheel 1a.
, 1b are steered, the rear wheels 2a, 2b are steered in opposite phases, so the front and rear wheel static testers 41, 45 measure the steering angles of these front and rear wheels. 1 of the relationship between the front wheel steering angle and the rear wheel steering angle measured in this way.
An example is shown in the graph of FIG. As you can see from this graph, when the front wheels are steered to the right, the rear wheels are accordingly steered to the left (steered in the opposite phase), and this change in the steering angle of the rear wheels gradually decreases, and steering is not performed at a predetermined steering angle (maximum left steering angle) of 01 or more. The same holds true when the front wheels are steered to the left, and the rear wheels are steered in the opposite phase and with the change gradually becoming smaller up to the maximum right-hand steered angle θ2.

In addition, in the measurement of the steering angle of the front wheels and rear wheels by the static testers 41 and 45, the steering angle of the front wheel is determined by the touch sensor in the range where the steering angle is small (in the range of ±5 degrees). The angle is measured by the angle measuring means 60, and angles exceeding this range are measured by the encoder (rotation angle detector) 55 attached to the lower end of the rotating shaft 54 of the turntable 50. On the other hand, the rear wheel steering angle is measured by the touch. Rear wheel angle measuring means 16 consisting of a type sensor
Measured by 0.

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 when various vehicle speed signals are input, which are measured as described above, The comparative inspection means 100 compares the measured characteristics with the basic characteristics to determine whether the measured characteristics are within the required range of the basic characteristics and the maximum steering angles θl and θ2.
It is checked whether or not the steering characteristic is within a predetermined range as a basic characteristic set in advance, and if it does not meet the basic characteristic, the steering characteristic is adjusted to match this.

Next, an example of another inspection method according to the present invention will be explained.

For this inspection, the steering wheel 3 is reciprocated left and right around its horizontal direction, and the front wheels 1a, Ib
The vehicle is steered reciprocally within a predetermined range around its straight forward direction. In this case, the front wheel turning angle range may be a small range, for example, in this example, about ±3°. At this time, highly accurate steering angle measurement is performed by the front wheel angle measuring means 60 consisting of a touch type sensor. By steering this front wheel, the rear wheel 2
Since a and 2b are also steered, the characteristics are tested by measuring the steering angles of the front and rear wheels at this time.In order to make it easier to measure the steering of the rear wheels compared to the steering of the front wheels, Preferably, a vehicle speed signal that maximizes the steering ratio is input to the controller 33. Therefore, the connector 10 of the signal sending means 105
5b is connected to the controller 33 in place of the vehicle speed sensor of the vehicle to be inspected, and a vehicle speed signal (vehicle speed 0KIR/H or 1207 to /H) that maximizes the steering ratio is sent from the signal sending means 105 via the line 105a. A corresponding vehicle speed signal) is sent to the controller 33.

An angle measuring means 60 consisting of a touch type sensor of a front wheel and rear wheel static tester 41 to 45 measures the turning angle of the front wheels and rear wheels when the front wheels are turned by operating the steering wheel under the above conditions. 160.

When an example of this measurement result is expressed with the vertical axis showing the rear wheel steering angle and the horizontal axis showing the front wheel steering angle, a trajectory with a certain hysteresis is shown as a solid line in the graph of Fig. 16. can get. The reason why a trajectory 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, if the rear wheel steering angle is adjusted when the front wheel steering angle is zero, it is not possible to adjust the rear wheel steering angle based on either the rightward or leftward steering of the front wheels. Therefore, in the present invention, in the comparison inspection means 100 that receives the measurement signal, the curve β representing the midpoint of both trajectories is set to the origin on the graph. I am trying to check whether it passes or not. Of course, it is checked whether the trajectory curve obtained by steering to the right and the trajectory curve obtained by steering to the left are substantially point-to-image with the origin as the center. Then, the rear wheel steering means is adjusted so that the curve β passes through the origin.

In the vehicle using the four-wheel steering means shown in FIGS. 2 and 3, the neutral return springs 14a and 14b are precompressed, so the rear wheels 2a and 2b are moved to the straight-ahead position (the steering angle is When steering from the zero position) to either the left or right, there is a dead zone where the rear wheels are not steered when the front wheels are steered (in the graph, the trajectory curve is approximately (horizontal part) occurs. Therefore, for example, the front wheel steering angle α when this dead zone occurs is
! .

Read α2, both steering angles α1. It may be checked whether the median value of α2 is zero, that is, whether both dead zones are point symmetrical with respect to the origin.

In addition, in this example, a method for inspecting four-wheel steering characteristics was explained using an example of a vehicle having an electro-hydraulic four-wheel steering mechanism that controls its steering ratio and steering phase according to vehicle speed. The invention is not limited to this, and the same applies to vehicles 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 in accordance with the steering of the front wheels. It is.

In addition, the inspection device and method according to the present invention are not limited to the inspection shown in this example, but can also be used for various types of four-wheel inspection, such as inspection of the operation of a fail-safe mechanism, inspection of changes in rear wheel steering angle in response to changes in vehicle speed, etc. Used to test steering characteristics.

(Effects of the Invention) As explained above, according to the present invention, there is provided a turntable for front wheels in which the left and right front wheels are each supported so as to be steerable and movable back and forth, and the left and right rear wheels are respectively steerable and supported so as to be movable back and forth. It has a rear wheel turntable supported to be movable left and right, a front wheel steering angle measuring means for measuring the steering angle of the front wheels, and a rear wheel steering angle measuring means for measuring the steering angle of the rear wheels. The vehicle body is fixedly held with the left and right front and rear wheels of the vehicle supported by the front and rear turntables, respectively, to prevent the vehicle body from moving even if a lateral external force is applied to the vehicle body. Since the vehicle body is configured with a means for fixing the vehicle body, both the front and rear wheels supported by the turntable can be smoothly steered, and the change characteristics of the turning angle of the rear wheels relative to the turning of the front wheels can be accurately controlled. Not only can measurements be made quickly, but even if a horizontal external force is applied to the vehicle, the vehicle body fixing means can prevent the vehicle body from moving, so this external force will not cause the vehicle body to move, and the vehicle will not be able to steer. It becomes possible to measure angles accurately.

[Brief explanation of the drawing]

Fig. 1 is a plan view schematically showing a four-wheel steering system for a vehicle, Fig. 2 is a schematic plan view of the four-wheel steering system, Fig. 3 is a schematic perspective view showing a variable steering ratio mechanism, and Fig. 4 is a schematic plan view of the four-wheel steering system. is a graph showing the relationship between vehicle speed and steering angle, Fig. 5 is a plan view showing the testing device, Figs. 6 and 7 are front and plan views of the front wheel static tester, and Figs. 8 and 9 are A front cross-sectional view and a side view showing the turntable for the front wheels; FIG. 8A is a cross-sectional view showing the turntable along arrows ■-■; FIGS. 10 to 12 show the front wheel angle measuring means and the tester moving means. Figure 13 is a front view showing the turntable for the rear wheels, Figure 14 is a plan view showing the front wheel guide, Figure 15 is a sectional view showing the beam cover, Figure 16 is from FIG. 19 is a graph that does not show an example of measurement results of changes in rear wheel turning angle with respect to front wheel turning. 4... Front wheel steering means 6... Connection means 10...
- Rear wheel steering means 14a, 14b... Application 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 so, iso... Turntable Go, 160... Angle measuring means 70.1
70... Tester moving means Fig. 1 Fig. 4 Fig. 9 COO7 3<D Fig. 12 Fig. 14

Claims (1)

[Claims] (1) A device for inspecting the four-wheel steering characteristics of a vehicle having a four-wheel steering device that steers the rear wheels in response to the steering of the front wheels, the left and right front wheels being able to be steered freely in the front, back, left and right directions. Measuring the steering angle of a full-float front wheel turntable that is movably supported, a full-float rear turntable that supports left and right rear wheels so that they can be steered, and movable back and forth, left and right, respectively. a front wheel steering angle measuring means for measuring the steering angle of the rear wheels, a rear wheel steering angle measuring means for measuring the steering angle of the rear wheels, and a state in which the left and right front and rear wheels of the vehicle are respectively supported by the front wheel turntable and the rear wheel turntable. and a vehicle body fixing means for fixing and holding the vehicle body.