JPH0737927B2 - Vehicle 4-wheel steering characteristic inspection device - Google Patents

Description

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

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

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

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

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

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

(Problems to be Solved by the Invention) In this case, in order to measure the steered angles of the front wheels and the rear wheels, the front wheels and the rear wheels are respectively placed on rotatable turntables, and the steering wheel is operated. The front wheels are steered by the steering wheel, and the steering angle of the front wheels and the steering angle of the rear wheels that are steered according to the steering of the front wheels are measured to measure and inspect the steering characteristics of the rear wheels with respect to the front wheels. Done.
However, in this case, it is necessary for an inspector to operate the steering wheel each time, and it is difficult to automate the measurement of the steering characteristics.

(Means for Solving Problems) In view of the problem of automation of measurement in the case where the front wheels are steered by operating the steering wheel, the present invention automatically steers the front wheels. An object of the present invention is to solve the above problems by providing an inspection device capable of automatically performing a characteristic inspection of wheel steering.
It is constructed as follows. That is, this device includes a front wheel turntable on which the left and right front wheels are mounted so that they can be steered, a rear wheel turntable on which the left and right rear wheels are mounted, and the steering angle of the front wheels. Front wheel turning angle measuring means for measuring the front wheel, rear wheel turning angle measuring means for measuring the turning angle of the rear wheels, and rotating means for rotating the front wheel turntable. The front wheels placed on this table are rotated to steer, and the steered angles of the front wheels and rear wheels at this time are measured by the front wheel steered angle measuring means and the rear wheel steered angle measuring means. It is configured to inspect the property.

(Operation) By using the above inspection device, the front wheels are steered by rotating the front wheel turntable on which the front wheels are placed by the rotating means, and the steering angles of the front wheels and the rear wheels at this time are respectively changed. The steering characteristics of the rear wheels with respect to the front wheels are measured and inspected by measuring the steering angles of the front and rear wheels. In this case, the steering of the front wheels is performed by the rotating means, and the steering wheel must be operated. Therefore, it becomes easy to automate the measurement and inspection of the steering characteristics.

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

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

Here, first, a method for performing a characteristic inspection of the above-described four-wheel steering device will be schematically described. In order to perform this characteristic inspection, first, the front wheels 1a, 1b and the rear wheels 2a, 2b are placed on rotatable turntables, respectively, and at this time, the front wheel turntable on which the front wheels 1a, 1b are placed is mounted. The rotation means rotates the front wheels to steer them, and at the same time, the steered angles of the front wheels 1a and 1b2 are measured. In this way, when the front wheels 1a, 1b are steered,
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 connecting means 6, and the rear wheel steering means 10 controls the steering amount and vehicle speed of the front wheels 1a, 1b. Since the rear wheels 2a, 2b are steered according to the above, the steering angles of the rear wheels 2a, 2b at this time are also measured. And by these measurements, the front wheels 1a, 1b
The change characteristic of the steered angle of the rear wheels 2a, 2b with respect to the steered angle is detected, and this characteristic is compared and compared with a preset basic characteristic, and it is inspected whether or not the basic characteristic is met. If the measured characteristic does not match the basic characteristic, the four-wheel steering system is adjusted so that the desired characteristic can be obtained. In this case, the operation of the inspection device can be easily automated by automating the operation of the rotating means and the measurement of the turning angle by the front wheel and rear wheel turning angle measuring means.

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

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

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

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

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

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

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

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

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

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

FIG. 5 is a plan view showing an inspection device 40 for toe-in adjustment and four-wheel steering characteristic inspection. This device 40 includes a front wheel static tester 41 for measuring front wheel toe-in angle, steered angle, etc. The front wheel guide 43 that guides the left and right front wheels to the front wheel static tester 41, the rear wheel static tester 45 that measures the toe-in angle, the steering angle, etc. of the rear wheel, and the left and right rear wheels on the rear wheel static tester 45. Rear wheel guide to guide
47 and 47 are arranged side by side in a line as shown in the figure, and the vehicle is transported in the direction of arrow A and the front and rear wheels are guided by the front and rear wheel guides 43 and 47, respectively. It is designed to be positioned above 41,45. The device 40 includes a signal sending means 105 for sending a vehicle speed signal and the like to the vehicle to be inspected and the device 4.
It has a comparison inspection means 100 for comparing the four-wheel steering characteristic measured by 0 with a preset basic characteristic. Therefore, the comparison inspection means 100 is connected to the lines 100a to 100d to which the measured values of the turning angles of the front and rear wheels are connected, and the signal transmission means 10
A line 105a having a connector 105b connected to the controller of the vehicle is connected to the line 5.

A front view of FIG. 6 shows the front wheel static tester 41 in detail along arrow VI-VI, and a detailed plan view of this static tester 41 is FIG. The static tester 41 consists of a pair of left and right testers that are line-symmetrical in order to measure the toe-in angle and steered angle of the left and right front wheels, as shown in the figure. Are given the same numbers, and only one of them will be described. The static tester 41 includes a full float type turntable 50 mounted on a support base 41a for supporting the front wheels so that the front wheels can be steered and moved left and right and front and rear, and the front wheels placed on the turntable 50 have tires. Front wheel angle measuring means 60 for contacting the side surface to measure the toe-in angle, steered angle, etc. of the front wheels, and a tester moving means mounted on the support base 41a for moving the front wheel angle measuring means 60 in the vehicle width direction. Composed of 70 and. The front wheel angle measuring means 60 has a measuring plate 61 that comes into contact with the tire side surface of the front wheel, and the tester moving means 70
By a touch sensor that abuts a measurement plate 61 on the tire side surface of the front wheels placed on the turntable 50 by moving the measurement table 61 and measures the inclination of the measurement plate 61 to measure the toe-in angle and the steering angle. Has been done.

The turntable 50 will now be described in detail with reference to FIGS. 8 and 9 and the structure of the turntable 50 will be described. The turntable 50 has a frame 51 made of a plurality of members fixedly mounted on the support base 41a, and a plurality of bearings 52 are fixedly mounted on the upper surface of the frame 51 side by side on the same circumference. The bearing 52 has a rotatable ball 52a, and the ball 52a supports the table 53 so as to be rotatable and movable in the front, rear, left, and right directions. This table
Reference numeral 53 denotes a front wheel placed on and supported by the front wheel 53. Front and rear guides 53a, 53a for positioning the front wheel in the front-rear direction are provided, and the front wheel abuts on the inner surface of the front wheel in the width (left-right) direction. Left and right guide plates 53b for positioning
Is provided. Further, a rotary shaft 54 extending downward from the center thereof is attached to the table 53, and an encoder 55 for detecting a rotation angle of the table 53 is attached to a lower portion of the rotary shaft 55. Further, a driven gear 54b that rotates integrally with the rotating shaft 54 is attached to the lower side of the encoder 55, and the driven gear 54b meshes with a drive gear 82 that is rotationally driven by a motor 81 as a rotating means. This motor 81 is supported by a support plate 83 which is movable integrally with the table 53 in the front-rear direction and left-right direction, but is prevented from rotating.
The table 54 can be rotated by rotating 54. As a result, the front wheels placed on the table 53 can be moved to the motor without operating the steering wheel.
It becomes possible to steer by driving 81. Conveyor plates 51b and 51b for smoothly conveying the front wheels to the table 53 are mounted on the frame 51.
It is attached with the front and back sandwiched. In addition, frame 51
Are provided with shaft holding plates 56, 56 which are opposed to each other so as to sandwich the rotary shaft 54 in the front-back direction and are movable in the front-back direction. The center parts 58a of the shaft-holding plates 56, 56 are rotatable around the frame 51. Are respectively connected to the upper ends of the arms 58 attached to the. The lower end 58c of the arm 58 is connected to both ends of the cylinder 59, and the arm 58 is rotated by the expansion and contraction of the cylinder 59 to move the shaft holding plate 56 back and forth.
Both shaft holding plates 56, 56 move closer to each other when 59 extends, and move away from each other when contracting. FIG. 8A is a cross-sectional view of the shaft holding plates 56, 56 and the rotary shaft 54 taken along the arrows VIII-VIII.
Right-angled triangular notches 56a are provided at the ends facing each other, and a portion 54a of the rotating shaft 54 facing the notches 56a has a square cross section in conformity with the notches. Therefore, when the cylinder 59 is extended and the two shaft holding plates 56, 56 approach each other, the cuts 56a, 56a become square-shaped portions 54a.
To hold the rotary shaft 54 in a fixed manner. Therefore, in the above state, the table 53 is also fixedly held with the front-rear guide 53 facing forward and backward.

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

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

Although the front wheel static tester 41 has been described above, the rear wheel static tester 45 will be described next. Similarly to the front wheel static tester 41, the rear wheel static tester 45 is composed of a pair of left and right testers, and each tester is a full-float type turntable 150, a rear wheel angle measuring means 160 composed of a touch type sensor, and a tester moving means 170.
It consists of and. As shown in FIG. 13, the turntable 150 includes a frame 151, a plurality of bearings (not shown) attached to the frame 151, and a table 153 supported by the bearings so as to be rotatable and movable back and forth and left and right. Although these have a slightly different shape from the front wheel turntable 50, their functions and essential structures are the same, and therefore their explanations are omitted. on the other hand,
The rotation shaft 154 extending downward from the table 153 has a smaller downward extension amount than the rotation shaft 54 of the front wheel table 53, and the rotation of this shaft is detected only by the square cross section 154a at the lower end thereof. No encoder is installed. This is because the steered angle of the front wheels in a four-wheel steered vehicle is large, and the steered angle cannot be measured only by the front wheel angle measuring means 60. The front wheel angle measuring means 60 performs accurate measurement, and the encoder 55 measures the angle exceeding the above range, but the steering angle of the rear wheel is ± ± 5
This is because the angle is within the range of °, so that the rear wheel angle measuring means 160 alone can sufficiently perform the measurement. The rotary shaft 154
A pair of shaft holding plates 156, 156 are arranged so as to sandwich the square cross section 154a at the lower end of the front and rear, and both shaft holding plates 156, 156 are arranged.
Is normally pushed and spread by a spring 157, but the rotary shaft 154 is fixedly held by being pushed by the cylinders 158, 158 arranged in front and rear and being held by the shaft holding plates 156, 156 to hold the square section 154a. It is supposed to be done. The rear wheel angle measuring means 160 for measuring the toe-in angle, the turning angle, etc. of the rear wheels and the tester moving means 170 for moving the rear wheel angle measuring means 160 in the vehicle width direction (left and right direction) are the same as those of the front wheel static tester 41. Since the function and the essential structure are the same, the description thereof will be omitted.

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

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

A method of inspecting the four-wheel steering characteristics of a vehicle equipped with a four-wheel steering device using the above-described inspection device 40 will be described by taking the four-wheel steering vehicle shown in FIG. 2 as an example. First, the cylinders 59, 158 and 158 of the front wheel turntable 50 and the rear wheel turntable 150 are extended to extend the shaft holding plates 56, 56 and 1
After the rotary shafts 54, 154 are fixedly held by 56, 156, the vehicle is transported onto the device 40 from the right side in the drawing in FIG. 5 in the direction of arrow A, and the front and rear wheel guides 43, 47 guide the front wheels 1a, 1b and the rear wheels. The wheels 2a and 2b are placed on the front and rear wheel static testers 41 and 45, respectively. Next, the heads 101a of the lifters 48, 49 are moved upward to raise the side sill portion of the vehicle body by the heads 101a to reduce the load from the front and rear wheels to the turntables 50, 150, and to hold the vehicle body in the horizontal direction of the vehicle body by an external force. To move to.
The lifting force of the vehicle body by the lifters 48, 49 is set so that a load to the extent that the tables 53, 153 are smoothly rotated by the steering of the front wheels and the rear wheels is left on the tables 53, 153. Next, the cylinders 59, 158, 158 of the front wheel turntable 50 and the rear wheel turntable 150 are contracted to release the fixed holding of the rotary shafts 54, 154 by the shaft holding plates 56, 56 and 156, 156, and the tables 53, 153 are brought into a full float state.

From this state, first, the toe-in adjustment of the front wheels and the rear wheels is performed. This toe-in adjustment is performed by steering means for the front and rear wheels.
The front and rear wheels are separately carried out in a state where the connection of the connecting means 6 of 4, 10 is released. In this case, the angle measuring means 6 consisting of the touch type sensors of the front wheels and the rear wheels static testers 41, 45
The toe-in angle is measured by 0,160, and the toe-in angle is adjusted to a predetermined value when the front and rear wheels face straight and the steering wheel faces horizontally.
After that, the front wheel and the rear wheel steering means are connected by the connecting means 6, but the description of the specific adjusting method will be omitted. The toe-in adjustment mentioned here includes not only so-called wheel and toe-in adjustment but also adjustment in the toe-out direction.

After the toe-in adjustment, the four-wheel steering characteristic is inspected. The adjustment of the four-wheel steering characteristics is performed by driving the motor 81 and rotating the table 53 in the full-float type turntable 50 for the front wheels to steer the front wheels placed on the table 53 and the front wheels 1a at this time. , 1b and the rolling axis angles of the rear wheels 2a, 2b are measured and inspected. A specific inspection method will be described below.

First, a simulated vehicle speed signal (for example, a vehicle element signal corresponding to a vehicle speed of 120 Km / H) is sent from the signal sending means 105 to the controller 33 via the line 105a so that the turning phase is the same and the turning ratio is maximized. To do. In this state, when the motor 81 of the turntable 50 is driven to steer the front wheels 1a, 1b, the rear wheels 2a, 1b
Since 2b is also steered in the same phase, the steered angles of these front and rear wheels are measured by the front and rear wheel static testers 41, 45. The graph of FIG. 16 shows an example of the relationship between the front wheel steering angle and the rear wheel steering angle measured in this way. In this graph, the vertical axis shows the rear wheel steering angle, the horizontal axis shows the front wheel steering angle, and the upper side of the vertical axis and the right side of the horizontal axis show the steering of the rear wheels and the front wheels to the right. There is. As can be seen from this graph, when the front wheels are steered to the right, the rear wheels are steered to the right accordingly (to the same phase). Is gradually decreased and the steering angle is not steered beyond a predetermined steering angle (right maximum steering angle) θ ₁ . The same applies to the case where the front wheels are steered to the left, and the rear wheels are steered in the same phase and gradually decreasing the change to the left maximum steering angle θ ₂ .

Next, a simulated vehicle speed signal (for example, a vehicle speed signal corresponding to a vehicle speed of 30 Km /) is sent from the signal sending means 105 to the controller 33 via the line 105a so that the steering phase becomes zero phase. Even if the motor 81 of the turntable 50 is driven to steer the front wheels 1a and 1b in this state, the rear wheels 2a and 2b should be kept in the zero phase and not steered. The steered angles of these front and rear wheels are measured by the front and rear wheel static testers 41, 45, and an example of the relationship between the steered angles of the front wheels and the steered wheels of the rear wheels thus measured is shown in FIG. Is a graph of. As you can see from this graph, if you steer the front wheels to the right,
The rear wheels are hardly steered, and only very small steered θ ₁ and θ ₂ are generated due to dimensional errors and the like.

Furthermore, a simulated vehicle speed signal (for example, a vehicle speed signal corresponding to a vehicle speed of 0 Km / H) is sent from the signal sending means 105 to the controller 33 via the line 105a so that the turning phase is reversed and the turning ratio is maximized. To do. Turntable 50 in this state
When the front wheel 1a, 1b is steered by driving the motor 81 of, the rear wheels 2a, 2b are steered in opposite phases, so the steered angles of these front and rear wheels are determined by the front and rear wheel static testers 41, 45. taking measurement. The graph of FIG. 18 shows an example of the relationship between the front wheel turning angle and the rear wheel turning angle thus measured.
As can be seen from this graph, when the front wheels are steered to the right, the rear wheels are accordingly steered to the left (to the opposite phase). Is gradually reduced and the steering angle is not steered beyond a predetermined steering angle (left maximum steering angle) θ ₁ .

The same applies to the case where the front wheels are steered to the left, and the rear wheels are steered in the opposite phase while gradually reducing the change to the right-side maximum steering angle θ ₂ .

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

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

Next, an example of another inspection method according to the present invention will be described.
For this inspection, the motor 81 of the turntable 50 is driven to reciprocally steer the front wheels 1a, 1b within the predetermined steered angle range around the straight traveling direction. In this case, the front wheel turning angle range may be a small range, for example, about ± 3 ° in this example. At this time, the front wheel angle measuring means 60 composed of a touch type sensor measures the steering angle with high accuracy. Since the rear wheels 2a, 2b are also steered by the steering of the front wheels, the steering angle of the front and rear wheels at this time is measured to perform the characteristic inspection. It is preferable to input a vehicle speed signal that maximizes the turning ratio to the controller 33 so that the rudder can be easily measured. Therefore, the connector 105b of the signal transmission means 105 is connected to the controller 33 instead of the vehicle speed sensor of the vehicle to be inspected, and the vehicle speed signal (vehicle speed) that maximizes the turning ratio is transmitted from the signal transmission means 105 via the line 105a. A vehicle speed signal corresponding to 0 km / h or 120 km / h) is sent to the controller 33.

The steering angle of the front wheels and the rear wheels when the front wheels are steered by driving the motor 81 under the conditions as described above is determined by the angle measuring means 60,160 composed of the touch type sensors of the front and rear wheel static testers 41,45. taking measurement. An example of this measurement result
When the rear wheel steering angle is shown on the vertical axis and the front wheel steering angle is shown on the horizontal axis, a locus having a certain hysteresis is obtained as shown by the solid line in the graph of FIG. The reason why the locus having hysteresis is obtained is that there is backlash in the connection system between the front wheel steering means and the rear wheel steering means. In this case, the adjustment of the rear-wheel steering angle when the front-wheel steering angle is zero is adjusted based on either the right or left steering of the front wheels. Since the steered angle of the rear wheels is deviated and the running stability is impaired, in the present invention, in the comparative inspection means 100 receiving the above measurement signal, the curve β representing the midpoint of both loci is the origin on the graph. I try to inspect whether or not it passes. That is, it is inspected whether or not the trajectory curve obtained by turning the steering wheel to the right and the trajectory curve obtained by turning the steering wheel to the left are substantially point-symmetrical with respect to the origin. Then, the rear wheel steering means is adjusted so that the curve β passes through the origin.

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

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

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

(Effects of the Invention) As described above, according to the inspection device of the present invention, the front and rear turntables for the front and rear wheels, on which the left and right front wheels and the left and right rear wheels are mounted so that they can be steered respectively, are provided. Front wheel and rear wheel turning angle measuring means for respectively measuring the turning angles of the front wheels, and rotating means for rotating the front wheel turntable. The rotating means rotates the front wheel turntable and mounts it on this table. The front wheels are steered, and the steering angles of the front wheels and the rear wheels at this time are measured by the front wheel steering angle measuring means and the rear wheel steering angle measuring means to inspect the steering characteristics. Therefore, it is not necessary to operate the steering wheel in order to steer the front wheels, and it suffices to drive the rotating means, which facilitates automation of measurement and inspection of the steering characteristics.

[Brief description of drawings]

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

Claims (1)

[Claims] 1. A device for inspecting the four-wheel steering characteristics of a vehicle having a four-wheel steering device adapted to steer the rear wheels according to the turning of the front wheels, wherein the left and right front wheels are mounted so as to be steerable. Front wheel turntables, rear wheel turntables on which the left and right rear wheels can be steered freely, front wheel turning angle measuring means for measuring the front wheel turning angle, and rear wheel turning A rear wheel turning angle measuring means for measuring an angle, and a rotating means for rotating the front wheel turntable. The front wheel is placed on the table by the rotation of the front wheel turntable by the rotating means. The steering characteristic is inspected by measuring the steering angles of the front wheels and the rear wheels at this time by the front wheel steering angle measuring means and the rear wheel steering angle measuring means. Wheel steering characteristic inspection device.