JPS63193030A - Method for inspecting four-wheel steering characteristic of vehicle - Google Patents

Abstract

PURPOSE:To accurately and rapidly inspect the characteristics of a steering apparatus, by a method wherein front wheels are reciprocally turned left and right so as to pass the position where the steering angle thereof becomes zero and it is inspected whether the center of the play zone of rear wheels coincides with the zero position of the steering angle of the front wheels. CONSTITUTION:A steering wheel is reciprocally operated left and right centering around the horizontal direction thereof to turn front wheels by about + or -3 deg.. Hereupon, since rear wheels are also turned, the steering angles of the front and rear wheels are measured. In this measurement, a car speed signal maximizing a steering ratio is inputted to a controller. When the results of measurement are shown so that the steering angle of the rear wheels is shown on a vertical axis and that of the front wheels is shown on a horizontal axis, a locus having definite hysteresis is obtained. Herein a play zone (a part where a locus curve becomes almost horizontal) wherein the rear wheels are not steered with respect to the steering of the front wheels is generated. Hereupon, the steering angles alpha1, alpha2 of the front wheels when the play zone is generated are read by a comparing inspection means to inspect whether the meridian of the steering angles alpha1, alpha2 becomes zero and a rear wheel steering means is adjusted so that the meridian becomes zero. By this method, steering sensation can be improved.

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 specifically, relates to a method 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 both the front and rear wheels has recently been proposed.
It has been investigated.

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.

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 not steered in a range where the front wheels are steered small. It can be seen that there is a need for a four-wheel steering system that steers the rear wheels in the same direction, but 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. It has been proposed to perform variable control to improve maneuverability, driving stability, etc. 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 steering ratio are varied by 1tlJm depending on the vehicle speed.

(Problem to be solved by the invention) In a conventional vehicle that steers only two wheels, the front wheels are steered proportionally to the operation of the steering wheel, so the horizontal position of the steering wheel and the straight direction of the front wheels are However, in a four-wheel steering system, the front wheels are steered proportionally in response to steering wheel operations, but the rear wheels are steered proportionally depending on the steering angle of the front wheels and the vehicle speed. Since steering is performed based on the rudder characteristics, conventional adjustments alone do not adequately test the steering characteristics of the rear wheels relative to the front wheels, and there is a problem in that the running stability of the vehicle cannot be fully guaranteed if left as is. . In particular, if the front wheel steering angle is zero and the rear wheel steering angle is not also zero, the direction of the rear wheels will deviate from the predetermined direction in response to the operation of the steering link wheel, and the steering feeling will be affected. There is a problem that it may be damaged. In addition, in order to improve driving stability, there is a dead zone where the front wheels are steered but the rear wheels are not steered near the position where the front wheel steering angle is zero and the rear wheel steering angle is zero. However, in this case, setting the dead zone and the front wheel turning angle becomes a problem.

(Means for Solving the Problems) In view of the above-mentioned problems, the present invention aims to solve the above-mentioned problems by providing a method for accurately and quickly testing the characteristics of a four-wheel steering system. As a means for that purpose, the inspection method of the present invention causes the front wheels to be steered by operating a steering wheel, etc., and the vehicle is steered according to the steering angle of the front wheels at this time and the steering of the front wheels. The system measures the steering angle of the rear wheels, detects the change characteristics of the steering angle of the rear wheels relative to the steering angle of the front wheels, and tests whether or not this characteristic corresponds to the characteristic specified in A. . In particular, in the present invention, taking into consideration the dead zone set near the position where the front wheel steering angle is zero and the rear wheel steering angle is also zero, it is possible to The purpose of the present invention is to provide a method that can accurately test whether the wheel steering angle is also zero, and for this reason, in the present invention, the front wheels are reciprocated left and right through the position where the wheel steering angle is zero. The vehicle is steered and the steering angles of the front wheels and rear wheels are measured at this time, and it is checked whether the center of the dead zone detected by the measurement approximately coincides with the position where the front wheel steering angle becomes zero. That's what I do.

(Function) According to the above method, the steering characteristics of the rear wheels relative to the front wheels can be detected accurately and quickly, and the steering characteristics of the rear wheels relative to the front wheels can be detected accurately and quickly, and near the position where the front wheels are turned to zero, that is, the position where the front wheels are facing in the straight-ahead direction. Since it is possible to reliably check whether the center of the dead zone that occurs when the front wheels are steered coincides with the position where the front wheel steering angle is zero, it is possible to reliably check whether the center of the dead zone that occurs when the front wheels are steered coincides with the position where the front wheel steering angle becomes zero. It is possible to check whether the rear wheels follow the direction of the operation and are steered correctly, and the four-wheel steering system is adjusted according to this test to adjust the direction of the steering wheel to the left or right. It is possible to improve the feeling of four-wheel steering when operating.

(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 lb 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 according to the operation of a steering wheel 3.
is steered by rear wheel steering means 10. The steering 1 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 the amount of steering, 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. At this time, in the vicinity of the position where the steering angles of the front wheels 1a, lb and the rear wheels 2a, 2b are both zero, even if the front wheels 1a, lb are steered, the rear wheels 2'a, 2'
The structure is such that there is a dead zone in which the wheel b is not steered. Note that the transmission bodies 5a and 5b are connected via a connecting means 6, and these transmission bodies 5a and 5b are connected to the front wheels 1a and 1b.
It may be a shaft that mechanically transmits the steering of the front wheels 1a, 1b to the rear wheel steering means 10 (or a cable that transmits the steering of the front wheels 1a, 1b 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 operate the steering wheel 3 and adjust the front wheel steering wheel m4.
The left and right front wheels 1a, Ib are steered by the steering wheel, and the steering angles of the front wheels 1a, 1b2 are simultaneously measured. When the front wheels 1a, 1b are steered in this way, the steering of the front wheels 1a, lb is carried out by the transmission bodies '5a, 5b connected by the coupling means 6.
is transmitted to the rear wheel steering means 10 via the rear wheel steering means 1.
0 steers the rear wheels 2a, 2b according to the amount of steering of the front wheels 1a, 1b, the vehicle speed, etc., so the rear wheels 2a, 2b at this time
Also measure the steering angle. Then, the rear wheels 2a, 2 with respect to the steering angles of the front wheels 1a, Ib obtained by these measurements are calculated.
If the change characteristics of the steering angle in b are expressed on orthogonal coordinates with the front wheel steering angle on the horizontal axis and the rear wheel steering angle on the vertical axis, when the front wheel steering angle becomes zero, the rear wheel steering angle also changes. However, near the position where both become zero, a dead zone appears where the rear wheels are not steered with respect to the front wheels being steered.

Therefore, it is checked whether the midpoint of this dead zone corresponds to the position where the front wheel turning angle becomes zero. In this test, if the center of the dead zone does not coincide with the zero position of the front wheel steering angle, the four-wheel steering system is adjusted so that the center of the dead zone coincides with the zero position.

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 explain the toe-in adjustment of the 'yJ rear wheels and the characteristic test of this giM in a vehicle equipped with this system. The specific method and apparatus for carrying out this will be explained.

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 meshes with a first pinion 3a formed at the lower end of the steering wheel 3, and tie rods 4b, 4b connected to both ends of this rod 4a. Tie rod 4b, 4b
It consists of knuckles 4c, 4c connected to the outer ends of the front wheel steering rod 4 in response to the operation of the steering wheel 3.
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 formed with a second rack that engages with a second pinion 5C provided at the front end of the rotation transmission shaft (transmission body) 5a.
When is moved in the vehicle width direction, the rotation transmission shaft 5a is simultaneously rotated via the second and nion 5c. 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, and the rear wheels are adjusted according to the steering phase and 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, 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 knuckle 17°11 supports the rear wheel 2b in a steerable manner, and the movement of the rear wheel steering rod 15 in the vehicle width direction allows the rear wheel 2b to be steered.
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 and 13b divided by the piston 12,
A hydraulic actuator consisting of 14b is attached. The left and right hydraulic chambers 13a, 13 of this hydraulic actuator
b is a hydraulic line 39a from the control valve 38.
, 39b are connected, and a hydraulic actuator is actuated by the hydraulic pressure supplied from the control valve 38 to move the rear wheel steering rod 15 in the vehicle width direction, thereby steering the rear wheels. In addition, the control valve 38
Hydraulic oil in a tank 35 is pressurized and supplied to the tank 35 by a pump 36. This control valve 38 is constructed of a known spool valve type, and includes a cylindrical valve housing 38a integrally connected to the rear wheel steering rod 15 via an arm 15a, and this valve housing 38a.
The hydraulic actuator is configured to move the valve housing 38a together with the rear wheel steering rod 15 in accordance with the movement of the spool valve 38i1 in the vehicle width direction. Hydraulic pressure is selectively supplied to the hydraulic chambers 13a and 13b. 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.

In this case, the neutral return springs 14a, 14b bias and hold the rear wheel steering rod 15 so that the rear wheel steering angle becomes zero;
b is precompressed and placed in the left and right hydraulic chambers 13a and 13b, so when moving the rear wheel steering rod 15 from a state where the rear wheel steering angle is zero to the right or left (when moving the rear wheel to the right or left) (in the case of steering the vehicle), the rear wheel steering rod 15 is not moved in the vehicle width direction unless the oil pressure in either the left or right hydraulic chambers 13a, 13b reaches a predetermined value or higher. Therefore, at a position where the rear wheel steering angle is zero (at this time, the front wheel steering angle is also zero), there is a dead zone in which the rear wheels are not steered within a predetermined range of the front wheel steering angle even if the front wheels are steered. will occur.

The hydraulic lines 39a and 39b are connected to a normally open fail-safe solenoid valve 37 via hydraulic lines 37a and 37b, respectively, and the solenoid 37C of this valve 37 is energized to open the valve 3.
When 7 is opened, both hydraulic chambers 1 of the hydraulic actuator
The oil pressures in 3a and 13b become equal, and the neutral return spring 1
The piston 12 is positioned at the neutral position by the urging force of the rear wheels 2a and 14b, and the steering angle of the rear wheels 2a and 2b is always zero.
A fail-safe mechanism is activated that sets the steering characteristics of the vehicle to a two-wheel steering state.

The movement of the spool valve 38b in the vehicle width direction is caused by the variable steering ratio mechanism 20 receiving rotation from the rotation transmission shaft 5b.
The variable steering ratio mechanism 2
0 will be explained using FIG. This steering ratio variable mechanism 2
0 is equipped with a swinging arm 22 whose base end is swingably supported by a U-shaped holder 21 via a support pin 22a, and the holder 21 is attached to a casing (not shown) fixed to the vehicle body with the above-mentioned spool valve. It is rotatably supported via a support shaft 21a having a rotation axis z2 perpendicular to the movement axis 9J1 of 38b. The support bin 22a of the swing arm 22 has both axes 9
. and the movement axis 9Js of the spool valve 38b.
The inclination angle formed by the movement axis 9. The angle of inclination made with respect to a plane perpendicular to s (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
3a is slidably supported by the rotation imparting arm 24 via a ball joint 23C. This rotation imparting arm 24 is aligned with the axis of movement! Support shaft 24 on top
It consists of a large-diameter bevel gear rotatably supported via a bevel gear, and a bevel gear 5d attached to the rear end of the rotation transmission shaft 5b is meshed with the bevel gear, and the steering wheel 3
The rotation is transmitted to the rotation imparting arm 24. Therefore, the rotation arm 24 and the connecting rod 23 rotate about the movement axis 9J1 by an amount corresponding to the rotation angle of the spooling wheel 3, and the swing arm 22 swings around the support bin 22a accordingly. When the axis of the bin 22a coincides with the movement axis 9J1 of the spool pulp 38b, the ball joint 23a at the tip of the swing arm 22 only swings on the reference plane, and the spool pulp 38b Although it is held stationary, the axis of the bottle 22a is the moving axis 2! If the swing locus plane of the swing arm 22 is deviated from the reference plane by tilting to This displacement is transmitted to the spool pulp 38b via the connecting rod 24, and the spool pulp 38b moves along the axis of movement! Move along 2,1. 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, lb, 2a, 2b. Further, the support shaft 21a of the holder 21 is controlled by a stepping motor 26.
A steering ratio sensor 21 comprising 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 determined.

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, When the phase is opposite, the steering ratio is maximum and the vehicle speed is 30? CIl
/H, two-wheel steering is in the zero phase state, and the vehicle speed is 12
This is done so that the steering ratio is maximized with the same phase at 0/m/H.

Next, a device for testing the four-wheel steering characteristics of a vehicle having a four-wheel steering device 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 40 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; This front wheel static tester 4
1, a front wheel guide 43 that guides the left and right front wheels, a rear wheel static tester 45 that measures the toe-in angle, steering angle, etc. of the rear wheels, and a rear wheel guide that guides the left and right rear wheels to the rear wheel static tester 45. 47 are arranged in a line as shown in the figure, and the front and rear wheels are guided by the front and rear wheel guides 43 and 47, respectively, by transporting the vehicle in the direction of the arrow to perform a front and single wheel static tester. 41.45
It is designed to be positioned above the Note that this device 40 includes a signal sending means 105 that sends a fail signal, a vehicle speed signal, etc. to the vehicle to be inspected, and a comparative test that compares the four-wheel steering characteristics measured by the device 40 with preset basic characteristics. It has means 100. For this purpose, 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 comparative inspection means 100, and a line 105a having a connector 105b connected to the vehicle controller is connected to the signal sending means 105. It is connected.

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. The front wheel angle measuring means 60 has a measuring plate 61 that abuts the tire side of the front wheel, and the measuring plate 61 is brought into contact with the tire side surface of the front wheel placed on the turntable 50 by movement by the tester moving means 10. At the same time, the inclination of this measuring plate 61 is measured 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 in the front and rear directions, and movable in the front direction.
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 580 of 8 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
6.56, the notches 56a, 56a sandwich 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 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. In this state, the measurement plate 61 is rotatable around the ball joint 62a, but the compression spring 63a is attached to the frame 65.
, tension spring 63b and link 63c, it is held vertically as shown in the figure. In addition,
The measuring plate 61 is held in an upright state when no external force is applied to it. When the measuring plate 61 receives an external force, the measuring plate 61 is held in an upright state by the deformation of the link 63c of the springs 63a and 63b. 61 is rotated around the ball joint 62a in response to external force. For this reason,
When the measuring plate 61 is brought into contact with the side surface of the tire of the front wheel, the measuring plate 61 is tilted according to the inclination of the tire, so by measuring the inclination of this measuring plate, the toe-in angle, steering angle, and camber angle of the front wheel can be determined. 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 85. This displacement measuring device 64 has a probe 64a that projects forward and is movable back and forth, and is attached to the left, right, and above the ball joint 62a, as shown in FIG. 12. This probe 64a comes into contact with contact dust 61a fixed to the measurement plate 61 when the measurement plate 61 comes into contact with the side surface of the tire, and when the measurement plate 61 is inclined, each Since there is a difference in the amount of movement of the probe 64a in the longitudinal direction (the amount of movement in the longitudinal direction within the displacement measuring device 64), the toe-in angle, steering angle, camber angle, etc. can be detected from this difference. 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 devices 64 arranged on the left and right sides of the ball joint 62a, and the average value of the above-mentioned mountain radius 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 devices 64 disposed on the left and right sides of the ball joint 62a are sufficient. In addition, these displacement measuring devices 64
etc. are covered by 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 idle rods 72, 72 and these guide rods 72. A transport rod 74 extending back and forth in the darkness of γ2 is supported.

On each guide rod 72 are two guide legs 67, -6 fixed to the lower surface of the frame 65 of the front wheel angle measuring means 60.
1 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. Furthermore, a thread is formed on the outer periphery of the transport rod 74, and a threaded bush 668 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 7 attached to its end.
5a meshes with a second sprocket T5c mounted on the shaft of the motor 7B via a chain 75b, and by rotationally driving the motor 16 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 7 of the tester moving means 10 is
1 has two limit switches 73 separated in the front and back direction.
73 is attached to the frame 65 of the front wheel angle detection means 60, and a pair of switch plates 68 and 66 facing the limit switch 73 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 measuring means 60, and the forward and backward movement position of the front wheel angle measuring 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 is comprised of a full float type turntable 150, a rear wheel angle measuring means 160, and a tester moving means 110. There is. 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. These have a slightly different shape from the front wheel turntable 50, but their functions and essential structures are the same, so a description thereof will be omitted. On the other hand, the rotating shaft 1 extending downward from the table 153
54 has a smaller downward extension than the rotating shaft 54 of the front wheel table 53 (and has a square section 1 at its lower end).
54a, but no encoder for detecting the rotation of this shaft is attached.

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°. In addition, 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 rotating shaft 154 in the front and rear.
The two wheel retaining plates 156, 156 are normally pushed apart by a spring 157, but the two wheel retaining plates 156 are pushed by respective cylinders 158, 158 disposed at the front and rear.
．． The rotating shaft 154 is held fixed by the square cross-sectional portion 154a being held between the rotating shafts 156. A rear wheel angle measuring means 160 for measuring the toe-in angle, steering angle, etc. of the rear wheels, and a tester moving means 170 for moving the rear wheel angle measuring means 160 in the vehicle width direction (horizontal direction).
Since the function and essential structure are the same as those of the front wheel static tester 41, the explanation thereof 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. Jin's 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 having guide grooves 90a for guiding the vehicle towards the vehicle, and these guide bodies 90.90 are movable in the vehicle width direction (left and right direction). In addition, guide plates 91,91 which are opened in the tangential direction in a diagonal shape are installed in order to correctly guide the front wheels into the guide groove 90a. The kudzu frames 96 and 97 facing the outer surfaces of both guide bodies 90 and 90 have a rotatable first frame extending to the right in the figure.
An arm 92a and a second arm 92b are attached, and both arms 92a, 92b are connected by a first connecting rod 93. Further, as shown in the figure, the first arm 92a is connected to the guide body 90 that supports the right front wheel by a second connecting rod 95, and the second arm 92b is connected to the frame 97 facing the outer surface of the guide body 90 that supports the left front wheel. For installation, a third arm 92c extending forward (to the left in the figure) from the section is rotatably attached integrally with the second arm 92b, and this third arm 92c is attached to a third connecting rod as shown in the figure. It is connected by 94 to a guide body 90 that supports the left front wheel. For this reason, the first connecting rod 93 is connected to the cylinder (
(not shown) etc., both guide bodies 90, 90 can be moved in opposite directions in the vehicle width direction, so that even if the front wheels have different treads, they can be moved in the vehicle width direction. The distance between both guide bodies 90,90 can be adjusted.

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 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 full-float turntables, if an external force is applied to the car body in the horizontal direction, the turntables are forced to move the car body, 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, it is possible to reduce the weight of the vehicle that is applied to the tires placed on the turntable, thereby reducing the deformation of the tires and reducing the load on the turntable. is made small so that the turntable can 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 extending each cylinder 59, 158, 158 of the
, 154, the fifth one is placed on this device 140.
The vehicle is transported in the six directions of arrows from the right side of the figure, and the front wheels 1a,
lb and rear wheels 2a and 2b are placed on front and rear wheel static testers 41 and 45, respectively. Next, the head 101a of the lifter 48, 49 is moved upward, and the side sill portion of the vehicle body is lifted by the head 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 shafts 54, 154 by the shaft holding plates 56, 56 and 156, 156, and the tables 53, 153 are 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 angle measuring means 60, 160 of the front wheel and rear wheel static testers 41, 45
The toe-in angle is measured with Although the wheel steering means are connected, a detailed explanation of the adjustment method thereof will be omitted. The toe-in adjustment referred to here is
This includes not only so-called toe-in adjustment of the wheels, but also adjustment in the toe-out direction.

After the above-mentioned toe-in adjustment, the four-wheel steering characteristics are inspected. This adjustment of the four-wheel steering characteristics is performed by measuring and inspecting the relationship between the steering angles of the front wheels 1a and lb and the steering angles of the rear wheels 2a and 2b as the steering wheel 3 is operated. is carried out, but here,
Only the method for testing four-wheel steering characteristics related to the method of the present invention will be described.

For this inspection, the steering wheel 3 is reciprocated left and right around its horizontal direction, and the front wheels 1a, 1b are
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°. As the front wheels are steered, the rear wheels 2a and 2b are also steered, so the characteristics are tested by measuring the steering angles of the front and rear wheels at this time. In order to facilitate the measurement of the rudder, it is preferable to input a vehicle speed signal that maximizes the steering ratio to the controller 33. Therefore, the connector 105b of the signal sending means 105 is connected to the controller 33 instead of the vehicle speed sensor 34 of the vehicle to be inspected, and this signal sending means 1
A vehicle speed signal (vehicle speed signal corresponding to a vehicle speed of 0 KIR/H or 1201 m/H) that maximizes the steering ratio is sent to the controller 33 from 05 to the line 105a.

The steering angles of the front and rear wheels when the front wheels are steered by operating the steering wheel under the above conditions are measured by the angle measuring means 60, 160 of the front and rear wheel static tester 41.45. 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. Here, in the vehicle using the four-wheel steering means shown in FIGS. 2 and 3, since the neutral return springs 14a and 14b are precompressed as described above, the rear wheels 2a
, 2b from the straight-ahead position @ (position where the steering angle is zero) to either the left or right direction, the dead zone in which the rear wheels are not steered relative to the front wheels (front wheel steering in the graph) A section where the trajectory curve is almost horizontal near where the angle becomes zero) occurs, but the position of this dead zone may have shifted to the left or right on the graph. The amount of steering of the rear wheels to the left and right is different and the steering feeling is impaired. Therefore, for example, the comparative inspection means 100 reads the front wheel turning angles α1°α2 when this dead zone occurs, and reads both turning angles α1°α2. It is checked whether the median value of α2 is zero, and the rear wheel steering means is adjusted so that the center value is zero.

In addition, when hysteresis occurs due to backlash and other factors as described above, depending on the steering direction, the adjustment of the rear wheel steering angle when the front wheel steering angle is zero can be adjusted to the right and left of the front wheels. If the adjustment is made based on steering in one of the directions, the steering angle of the rear wheels will deviate when steering in the other direction, and running stability will be impaired.
0, it is detected whether the curve β representing the midpoint of both trajectories passes through the origin on the graph. That is, it is checked whether the trajectory curve obtained by steering to the right and the trajectory curve obtained by steering to the left are approximately point symmetrical with respect to the origin, and the curve β is set so that it passes through the origin. Adjust the rear wheel steering means.

In the above, a method for inspecting four-wheel steering characteristics was explained using as an example a vehicle having an electro-hydraulic four-wheel steering system 411 that controls its steering ratio and steering phase according to the 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.

(Effects of the Invention) As explained above, according to the present invention, the front wheels are reciprocated left and right through a position where the steering angle becomes zero, and the steering angles of the front wheels and rear wheels at this time are This method measures whether the center of the dead zone detected by the measurement approximately coincides with the position where the front wheel steering angle becomes zero, so the steering link in a vehicle with a four-wheel steering system is It can be inspected to see if the rear wheels follow the steering wheel in the left/right direction and are steered correctly.The four-wheel steering system can be adjusted according to this inspection, and the steering wheel can be steered to the left or right. It is possible to improve the feeling of four-wheel steering when operating.

[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. Fig. 13 is a front view showing the turntable for the rear wheels, Fig. 14 is a plan view showing the front wheel guide, Fig. 15 is a sectional view showing the beam cover, Fig. 16 is a It is a graph which shows an example of the measurement result of the rear wheel steering angle change with respect to the front wheel steering angle. 4... Front wheel steering means 6... Connection means 10...
- Rear wheel steering means 14a, T4b... Neutral return spring 20... Steering ratio variable mechanism 26... Stepping motor 21... 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, 1
70... Tester moving means Fig. 1 Fig. 4 Fig. 9 Q O7 Fig. 12 Fig. 14 So'tIC%jzD Fig. 16

Claims (1)

[Scope of Claims] 1) Consisting of a front wheel steering means for steering the front wheels and a rear wheel steering means for steering the rear wheels in accordance with the steering of the front wheels, the front wheel steering angle is zero. 4-wheel steering characteristics of a vehicle having a 4-wheel steering system configured to create a dead zone in which the rear wheels are not steered even if the front wheels are steered near the position where the rear wheel steering angle is also zero. This is an inspection method in which the front wheels are steered back and forth to the left and right through a position where the steering angle becomes zero, and the steering angles of the front and rear wheels at this time are measured, and the steering angles of the front wheels and rear wheels are measured. A method for inspecting four-wheel steering characteristics of a vehicle, comprising inspecting whether the center of a dead zone substantially coincides with a position where a front wheel turning angle is zero.