JPH0338471A - Steering angle slow change mechanism - Google Patents

Abstract

PURPOSE:To enable natural four-wheel steering without a feeling of physical disorder by providing a cam groove on one of the end portion of a long lever connected to an input shaft and the end portion of a short lever connected to an output shaft, and providing a flexible driven arm on the other thereof, and engaging a pin connected to the forward end of the driven arm with the cam groove. CONSTITUTION:Even if an input lever 61 of an input shaft 14 is turned in connection with the handle operation, a pin 64 mounted on the forward end of a driven am 63 id just moved along a cam groove 65a, and output lever 65 of an output shaft 9 is not turned. When the turning angle of the input lever 61 exceeds a designated value, the pin 64 of the driven arm 63 is brought into contact with the end edge 65b of the cam groove 65a, and the output lever 65 is drawn by the pin 64 and turned with the flexion of the driven arm 63. The driven arm 63 is bent with respect to the input lever 61, so that the output lever 65 is slowly started behind input lever 61, and the rate of change of the turning angle of the output lever 65 gradually approaches that of the input lever 61. Accordingly, natural four-wheel steering without a sudden change can be accomplished.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a four-wheel steering vehicle in which the rear wheels are not steered when the steering angle is less than a predetermined value, and when the steering angle exceeds a predetermined value, the rear wheels are steered and the steering angle ratio ( This invention relates to a gradually changing steering angle ratio IJ structure in which the ratio of the rear wheel steering angle to the IiJ wheel steering angle is gradually increased from O.

[Conventional technology]

The present applicant has proposed, in Japanese Patent Application No. 63-218180, a steering angle ratio 6 control mechanism for a four-wheel steering vehicle, as shown by the broken line in FIG.
The application was filed for a system in which the front wheels are steered but the rear wheels are not, and the width of this dead zone increases as the vehicle speed increases. According to this steering angle ratio control mechanism, when driving at low speeds, even a slight turn of the steering wheel causes the rear wheels to be relatively largely steered in the opposite phase to the front wheels, demonstrating tight turning ability, while when driving at medium speeds, normal steering wheel turning In the angular range the rear wheels are hardly steered, and at high speeds the rear wheels are not steered at all.

[Problems to be Solved by the Invention] However, even with the above-mentioned steering angle ratio 111110 mechanism, when the steering angle from the straight-ahead position of the steering wheel exceeds a predetermined value (dead zone), the rear wheels are suddenly steered. As a result, the vehicle body behaves unnaturally, giving the driver a sense of discomfort.

In view of the above-mentioned problems, an object of the present invention is to gradually shift the operation of the rear wheel steering mechanism from a state where the rear wheels are not steered to a state where the rear wheels are gently steered to a steady state as the steering wheel turning angle increases. The object of the present invention is to provide a steering angle ratio gradual change mechanism.

[Means for Solving the Problems] In order to achieve the above object, the configuration of the present invention includes a system that controls an input shaft linked to a steering wheel and a rear wheel steering actuator.
lJt [l The output shafts connected to the valves are arranged parallel to each other, and a cam groove is formed on one end of the long lever connected to the input shaft and a short lever connected to the output shaft, and a cam groove is provided on the other side. Each is equipped with a driven arm, and the driven arm is 1) J! i! A bottle connected to the tip of the cam groove is engaged with the cam groove.

[Function] Even if the input lever 61 of the input shaft 14 is rotated in connection with the handle operation, the pin 64 at the tip of the driven arm 63 does not fit into the cam groove 6.
5a, the output lever 6 of the output shaft 9
5 is not rotated. When the rotation angle of the input lever 61 exceeds a predetermined value, the pin 64 of the driven arm 63 hits the edge 65b of the cam groove 65a, and the pin 64 is bent while the driven arm 63 is bent.
, the output lever 65 is rotated.

As a result of the driven arm 63 bending relative to the input lever 61, the output lever 65 is activated slowly behind the input lever 61, and the rate of change in the rotation angle of the output lever 65 is equal to the input lever 61.
gradually approaches that of .

Therefore, if the steering angle from the straight-ahead position of the steering wheel is less than a predetermined value, the rear wheels will not be steered, and if it exceeds a predetermined value, the steering angle ratio will gradually increase from 0, achieving natural four-wheel steering without sudden changes. .

[Embodiment of the Invention] FIG. 3 is a schematic diagram of a four-wheel steered vehicle equipped with a steering angle ratio gradual change mechanism according to the present invention. A four-wheel steering vehicle has a steering angle ratio gradual change mechanism A that transmits the rotation of an input shaft 14 interlocked with an output shaft 16 of a front wheel steering mechanism 15 to a control valve B in relation to the vehicle speed, and a steering angle ratio gradual change mechanism A that transmits rotation of an input shaft 14 that is interlocked with an output shaft 16 of a front wheel steering mechanism 15 to a rear wheel steering actuator C. It includes a servo III control valve B that fraudulently controls the hydraulic circuit, and a rear wheel steering actuator C that drives the rear wheels 51. The front wheel steering mechanism 15 is connected to the steering shaft 2
For example, when the handle 26a of the 6 is turned to the right, the arm 17 of the output shaft 16 rotates, the link 18 is pulled forward, the knuckle arm 22 is rotated clockwise about the support shaft 19, and the front wheel 20 is rotated. deflected to the right. Although only the right front wheel 20 is shown in FIG. 3, the knuckle arm of the left front wheel is operatively connected to the knuckle arm 22 of the right front wheel 20 by a tie rod 21. An arm 25 of the output shaft 16 and an arm 24 of the input shaft 14 are connected together by a link 23.

The steering angle ratio gradual change mechanism A according to the present invention includes an input lever 61 supported by a spline on the input shaft 14 so as to be slidable in the axial direction, and an output lever 6 fixedly supported on the output shaft (drive shaft of the control valve B).
5, and the pin 64 of the driven arm 63 bendably connected to the input lever 61 is connected to the cam groove 6 provided in the output lever 65.
5a. Both end edges of the cam groove 65a are inclined with respect to the axis of the output shaft 9. That is, as the bin 64 moves to the left, the range of movement becomes narrower. The output shaft 9 is positioned by a neutral return spring (not shown) so that the pin 64 is located at the center of the cam groove 65a when the handle 26a is in the straight forward position as shown in FIG.

The tip of the tfi1m lever 27, which is connected to the shaft 28 and extends upward, is engaged with an annular groove provided on the outer peripheral surface of the boss portion 12 of the input lever 61. Wheel 2 rotatably supported on the vehicle body side
A rod of an actuator 30 is connected to a lever 29 extending downward from the lever 8 . The actuator 30 is formed by fitting a piston 38 into a cylinder 37 in a well-known manner, and a rod protruding from the piston 38 is connected to the lever 29.

The amount of oil in the left end chamber of the cylinder 37 decreases as the vehicle speed increases, and when the piston 38 is returned to the left by the force of the spring, the boss portion 12 slides to the right and the bottle 64 moves into the cam groove 6.
Move to the wide part of 5a.

FIG. 1 is a front view of the steering angle ratio gradual change mechanism according to the present invention, viewed from the output shaft side end. An input lever 61 is spline-coupled to the input shaft 14, and a fan-shaped output lever 65 is coupled to the output shaft 9. An arc-shaped cam groove 65a is formed at the end edge of the output lever 65, and the width of this groove (the length from the left edge to the right edge 65b) is equal to the axis of the output shaft 9 as shown in FIG. Varies with respect to direction. The input lever 61 is longer than the output lever 65, and a driven arm 63 is connected to its tip by a pin 62. A pin 64 coupled to an end of the driven arm 63 is projected into the cam groove 65a and can be engaged with an edge 65b of the cam groove 65a.

As shown in FIG. 2, the driven arm 63 is biased by a neutral return spring 68 so as to be aligned with the input lever 61 in the neutral position. The neutral return spring 68 has an intermediate portion connected to the pin 62.
The hook is rotated by a pin 67 connected to the input lever 61, and both ends are locked to both side edges of the driven arm 63.

As shown in FIG. 3, the control valve B is a four-bottom neutral position open type directional control valve, and a neutral return spring (not shown) is installed inside the valve body 32 (hatching is omitted for ease of understanding). )
A spool 35 fitted so as to be able to move in the axial direction against the force of the threaded shaft 33 is coupled by the connecting means 34 so as to be able to move in the axial direction together with the screw shaft 33 . The right end of the screw shaft 33 is the output shaft 9
The lead is screwed into a large screw hole 31 formed at the end of the lead. The driven shaft 3 is spline-fitted into a spline hole 36 formed at the left end of the screw shaft 33 . When the spool 35 moves along with the rotation of the output shaft 9, pressure oil flows from the hydraulic pump 7 through 1!5! ! 53. 54 is supplied to one side,
Oil in the other pipe is returned to oil tank 8 via pipe 6.

The pipes 53 and 54 are the end chambers 42 of the rear wheel steering actuator C,
44. In the rear wheel steering actuator C, a piston 41 is fitted into a cylinder 45 to define end chambers 42 and 44, and a tie rod 47 coupled to the piston 41 projects outward from both end chambers of the cylinder 45. tie rod 47
is returned to the neutral position by the force of the return spring 43 housed in the end chambers 42 and 44, and holds the rear wheel 51 in the straight-ahead position. Both ends of the tie rod 47 are connected to a knuckle arm 49 via auxiliary rods 48, respectively. A knuckle arm 49 that supports the rear wheel 51 is rotatably supported on the vehicle body by a vertical support shaft 50. The movement of the tie rod 47 is transmitted to the lever 2 connected to the aforementioned driven shaft 3 via a remote cable (push-pull cable) 52 extending from the connecting member 46.

Next, the operation of the steering angle ratio gradual change Ill structure according to the present invention will be explained. In FIG. 3, for example, when the steering wheel 26a is turned to the right, the output shaft 16 of the front wheel steering mechanism 15 is rotated, the link 18 is pulled forward, and the knuckle arm 22 is moved to the support shaft 1.
9 in a clockwise direction, and the front wheel 20 is deflected to the right. At the same time, the rotation of the output shaft 16 causes the arm 25, link 23, and I! 24 to the input shaft 14 to the steering angle ratio gradual change mechanism. When the vehicle speed is below a predetermined value, the steering wheel 26a
When the turning angle (front wheel steering angle) exceeds a predetermined value, the rotation of the input lever 61 is transmitted to the output lever 65 via the pin 64 of the driven arm 63 and the cam groove 65a.

When the input lever 61 is rotated counterclockwise together with the input shaft 14 from the neutral position shown by the solid line in FIG. 1, the pin 64 of the driven arm 63 moves along the cam groove 658, and the pin 64 When the input shaft 61 hits the edge 65b of the groove 65a, the rotation of the input shaft 61 is transmitted to the output lever 65 via the pin 64 of the driven arm 63.

However, the arcuate movement locus of the end edge 65b of the cam groove 65a or the bottle 64 approaches the arcuate movement locus of the pin 62 of the input lever 61 (because the input lever 61 is longer than the output lever 65). Therefore, the driven arm 63 bends with respect to the input lever 61 using the pin 62 as a fulcrum.

For this reason, the output lever 6 is delayed in rotation of the input lever 61.
5 begins to rotate slowly, and when the driven arm 63 is bent at a substantially right angle to the input lever 61, the output lever 65 is rotated in response to the input lever 61. In other words, when the pin 64 engages with the edge 65b of the cam groove 65a, the ratio of the rotation angle of the output lever 65 to the rotation angle of the input lever 61 (this becomes the steering angle ratio) gradually increases.
As shown by the curved part of the solid line al in Fig. 4, the steering angle ratio is O.
The rear wheel steering angle gradually increases from then on, and eventually the rear wheel steering angle increases almost in proportion to the front wheel steering angle.

When the output shaft 9 is rotated, the spool 35 moves to the right together with the screw shaft 33, and pressure oil flows from the hydraulic pump 7 through the pipe 5 and the control valve B1 pipe 53 to the end chamber of the rear wheel steering actuator C. 42. Tie rod 4 along with piston 41
7 is pushed to the right, the knuckle arm 49 is rotated counterclockwise around the support shaft 50, and the rear wheel 51 is moved to the left (front wheel 2
0 and the opposite phase>. In this way, the vehicle's ability to turn in a tight corner while traveling at low speeds is exhibited. The oil in the end chamber 44 is returned to the oil tank 8 via the pipe 54 and the control valve B1 pipe 6.

When the vehicle speed increases, the actuator 30 moves the input lever 61 and the pin 64 of the driven arm 63 to the third position relative to the input shaft 14.
Pushed to the right in the figure, the pin 64 moves to the wide part of the cam groove 658, and the rear wheel steering angle changes along line a2 in FIG.

Note that when the steering wheel 26a is turned to the left, as in the case described above, as the turning angle of the steering wheel 26a increases and the dead zone is exceeded, the control valve 8 is slowly activated by the steering angle ratio gradual change mechanism A, and the input shaft 14 The input lever 61 rotates clockwise in FIG.
The engine 41 is driven to the left, and the rear wheel 51 is deflected to the right.

The rear wheel steering actuator C starts slowly, and the steering angle ratio gradually increases from O.

The embodiment shown in FIG. 5 has a cam groove 71a connected to the input lever 71, a driven arm 73 connected to the output lever 75 by a pin 72, and a pin 74 connected to the end of the driven arm 73, contrary to the previously described embodiment. is engaged with the cam groove 71a. The cam groove 71a is similar to the cam groove 65a shown in FIG.

[Effects of the Invention] As described above, the present invention has an input shaft linked to a steering wheel and an output shaft connected to a control valve that controls a rear wheel steering actuator that are arranged parallel to each other, and a long lever connected to the input shaft. One end of a short lever connected to the end and the output shaft is provided with a cam groove, and the other end is provided with a bendable driven arm, and a pin connected to the tip of the driven arm is engaged with the cam groove. When the turning angle of the steering wheel is less than a predetermined value, the rear wheels are not steered, and when the turning angle exceeds a predetermined value, the output lever is turned with the bending of the driven arm in response to the rotation of the input lever linked to the steering wheel operation. is delayed and rotates slowly, and the steering angle ratio gradually increases from 0. Therefore, since the rear wheel steering actuator is slowly activated by the control valve connected to the output shaft, natural four-wheel steering without any discomfort can be obtained.

[Brief explanation of drawings]

FIG. 1 is a front view of the steering angle ratio gradual change mechanism according to the present invention, FIG. 2 is a front view showing the main parts of the steering angle ratio gradual change mechanism, and FIG. 3 is the steering angle ratio gradual change mechanism of the present invention. 4 is a diagram showing the steering angle characteristics of the steering angle ratio gradual change mechanism, and FIG. 5 is a diagram showing the steering angle ratio gradual change mechanism according to the second embodiment of the present invention. FIG. 3 is a front view of the mechanism. A: Steering angle ratio gradual change mechanism B: 1lJIll valve C: Rear wheel steering actuator 9: Output shaft 14: Input shaft 61.
71: Input lever 63.73: Followed arm 64.74:
Bin 65.75 + output lever 65a, 71a: cam groove

Claims (1)

[Claims] An input shaft that is linked to the steering wheel and an output shaft that is connected to a control valve that controls the rear wheel steering actuator are arranged parallel to each other, with the end of a long lever connected to the input shaft and the end of a short lever connected to the output shaft. A steering angle ratio gradual change mechanism is provided with a cam groove on one side and a bendable driven arm on the other side, and a pin connected to the tip of the driven arm is engaged with the cam groove.