JPS63134378A - Rear wheel steering device for front and rear wheel steering car - Google Patents

Abstract

PURPOSE:To provide an optimum steering angle, by a method wherein, when a rotary shaft is rotated during steering, a conical crank shaft is axially moved by means of an axial feed mechanism simultaneously with rotation of the shaft. CONSTITUTION:With a steering wheel controlled, a rack bar is displaced to steer front wheels. A rotary shaft is rotated by means of a rack bar, and an input shaft 41 in a coupling mechanism A is rotated by one complete turn to rotate a conical crank shaft 42. Simultaneously, the conical crank shaft 42 is axially moved by means of a ball screw mechanism 45. Thereby, a coupling body 43 is rocked along with rotation of the conical shaft 42, and is axial moved along with axial movement of the conical crank shaft 42. Two movement of rocking and axial movement of the coupling body 43 are synthetized to transmit it to an actuating rod 30. This constitution enables rear wheels to be steered in a high reverse phase during low steering of front wheels.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rear wheel steering device for a front and rear wheel steered vehicle capable of steering the rear wheels of the vehicle in conjunction with the steering operation of the front wheels.

[Prior art]

In this type of rear wheel steering device, a rotating shaft that rotates in response to a front wheel steering operation is connected to an operating rod of a rear wheel side steering link mechanism, and the operating rod is moved in the axial direction in response to rotation of the rotating shaft. Conventionally, there has been a device equipped with a coupling mechanism that steers the rear wheels to the same phase side when the front wheels have a small steering angle and to the opposite phase side when the front wheels have a large steering angle. This is proposed in JP-A-61-9374.

However, in the device proposed in the same publication,
The coupling mechanism includes an input shaft that is rotatably assembled to a housing that is assembled to a vehicle body, is connected to the rotation shaft, has an eccentric shaft at a rear end, and is rotated by the rotation shaft; a cylindrical member rotatably assembled on an eccentric shaft and integrally equipped with a pinion at the front and an eccentric cam at the rear;
an internal gear that is fixed to the housing and meshes with the pinion; and an internal gear that is rotatably assembled on the eccentric cam of the cylindrical member and that is slidably guided in the vertical direction by a guide member provided on the actuating rod. The structure includes a slider that transmits the movement of the cam to the actuating rod as a displacement in the axial direction. Therefore, in this device, the two movements of revolution and rotation of the eccentric cam are combined by the rotation of the input shaft and transmitted to the slider, and from the slider to the actuating rod, the left-right movement of the combined movement is transmitted to the slider. Only that signal is transmitted and the rear wheels are steered.

[Problem that the invention seeks to solve]

By the way, in the above-mentioned conventional device, (1) By various combinations of the tooth ratio of the pinion and internal gear and the eccentricity of the eccentric cam, the rear wheel steering angle can be adjusted to suit the characteristics of the vehicle, which differs depending on the vehicle type. Although it is possible to set the wheel steering angle, there are restrictions on manufacturing gears such as modules when setting the gear ratio, so it is not possible to set it steplessly within a limited space. It is difficult to set the optimal rear wheel steering angle that matches the characteristics within a limited space.

■In setting the neutral position where the rear wheel steering angle is zero,
Input shaft axis, eccentric shaft and pinion axis.

The center of the eccentric cam and the center of the internal gear must be placed on the same line in the vertical direction before connecting the eccentric cam and the slider, which requires high manufacturing and assembly accuracy and reduces manufacturing costs. It becomes expensive.

There are problems such as.

[Means for solving problems]

In order to solve this problem, the present invention provides the above-mentioned rear wheel steering device for a front and rear wheel steered vehicle, in which the coupling mechanism is rotatably and axially movably assembled to the housing via a shaft feeding mechanism. a conical crankshaft that is connected to the rotating shaft and has a pin part inclined at a set angle with respect to the axis in the intermediate part and is moved in the axial direction by the shaft feeding mechanism; and a conical crankshaft that is rotatable on the pin part of the conical crankshaft. The rod part is attached to the conical crankshaft and has a rod part extending in the radial direction of the pin part, and the rod part is connected to the actuating rod via a conversion mechanism, and is oscillated by the rotation of the conical crankshaft to rotate the actuating rod. The configuration includes a connecting body that is displaced in the axial direction.

[Action of the invention]

In the rear wheel steering device according to the present invention, when the rotating shaft rotates in accordance with the steering when the front wheels are steered, the conical crankshaft is rotated by the rotating shaft and simultaneously moved in the axial direction by the shaft feeding mechanism. Therefore, the connecting body assembled on the pin portion of the conical crankshaft swings in accordance with the rotation of the conical crankshaft, and also moves in the axial direction in accordance with the axial movement of the conical crankshaft. The two motions, dynamic and axial, are combined and transmitted to the actuating rod via the conversion mechanism. Therefore, the actuating rod is displaced in its axial direction according to the above-mentioned combined movement,
When the front wheels have a small steering angle, the rear wheels are steered in the same phase, and when the front wheels have a large steering angle, the rear wheels are steered to the opposite phase side.

Therefore, in the rear wheel steering device according to the present invention, by appropriately setting the amount of feed per revolution of the conical crankshaft by the shaft feeding mechanism, and by appropriately setting the inclination angle of the bin portion of the conical crankshaft, The axial displacement of the actuating rod obtained by the rotation of the conical crankshaft can be set appropriately, and the rear wheel steering angle relative to the front wheel steering angle can be set in accordance with the characteristics of different vehicles depending on the type of vehicle.

〔Effect of the invention〕

By the way, in the rear wheel steering device according to the present invention, the feed amount by the shaft feed mechanism and the inclination angle of the bin part of the conical crankshaft can be adjusted without being subject to any manufacturing restrictions even within a limited space. Since each can be set steplessly as appropriate, it is possible to extremely easily set the optimum rear wheel steering angle within a limited space to suit the characteristics of different vehicles.

Further, in the rear wheel steering device according to the present invention, in setting the neutral position where the rear wheel steering angle is zero, only the position of the conical crankshaft in the rotational direction with respect to the housing is set at the set position, and then the coupling body is moved to the conversion mechanism. It only needs to be connected to the actuating rod through the connector, and the assemblability is extremely good (it can be manufactured at low cost).

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

1 to 8 show a first embodiment of a rear wheel steering device according to the present invention, and FIG. 5 schematically shows a front and rear wheel steered vehicle equipped with a rear wheel steering device according to the present invention. . In the vehicle shown in FIG. 5, the front wheel side steering link mechanism 10
Rank par 1) that constitutes the steering wheel WS
It is displaced in the left and right direction by the operation of
It is connected via tie rods 14 and 15 to knuckle arms 12 and 13 that give a steering angle to the steering angle. In addition, rack bar 1). Knuckle arm 12/13. Tie rod 14/1
A ball joint is interposed in each of the connecting portions 5. Further, the rear wheel steering device is connected to the rack bar 1) via a rotating shaft 20.

The rotating shaft 20 is divided into four shafts: a main shaft 21, a pair of front and rear intermediate shafts 22, 23, and a pinion shaft 24. ) is connected to. The main shaft 21 is rotatably supported by the vehicle body and extends a predetermined length from the front of the vehicle body toward the rear. Note that the number of divisions of the rotating shaft 20 can be changed as appropriate.

As shown in FIGS. 1 to 5, the rear wheel steering device includes a connecting mechanism A that connects the rotating shaft 20 and the operating rod 30, a link mechanism B that connects the rain rear wheel WR, and a connecting mechanism A. A power steering mechanism C is provided which connects the link mechanism B and assists in the force transmitted from the link mechanism A to the link mechanism B.

The coupling mechanism A includes an input shaft 41. which is attached to a housing H which is attached to the vehicle body. Conical crankshaft 42. It includes a ball screw mechanism, a connecting body 43, and a rotor 44.

The input shaft 41 is rotatably but immovably assembled in the housing H by a pair of bearings 51 and 52, and is connected at its tip to the intermediate shaft 23 of the rotating shaft 20 so as to be integrally rotatable. Inside the rear cylindrical portion 41a, the tip of a conical crankshaft 42 is connected via a ball spline 45 so as to be rotatable therewith and slidable in the axial direction. Note that the ball spline 45 is a known one,
Thereby, the sliding resistance in the axial direction between the input shaft 41 and the conical crankshaft 42 is reduced.

The conical crankshaft 42 has a pin portion 42a inclined at a set angle θ with respect to the axis L1 in the intermediate portion, and is assembled to the housing H via a ball screw mechanism at the rear end 42b. It is rotatable relative to H and movable in the axial direction. The ball screw mechanism is a shaft feeding mechanism that moves the conical crankshaft 42 in the axial direction at a predetermined feed amount when the conical crankshaft 42 rotates, and has a threaded groove 42C formed on the outer periphery of the rear end shaft portion of the conical crankshaft 42.
and a ball nut 4 that is fixed to the housing H and accommodates a large number of balls 46 that are circulated and supplied to the threaded groove 42C inside.
It is composed of 7.

In this embodiment, as is clear from FIG. 5, since the intermediate shaft 20 rotates in the same direction as the steering wheel WS, the ball screw mechanism is a left-handed screw, but the intermediate shaft 20 rotates in the same direction as the steering wheel WS. If the shaft 20 is configured to rotate in the opposite direction to the steering wheel WS,
The ball screw mechanism must be right-handed.

The connecting body 43 is connected to the pin portion 42a of the conical crankshaft 42.
A rod portion 43 is rotatably assembled on the top via a pair of bearings 53 and 54 and extends in the radial direction of the pin portion 42a.
a, and the pole bearing 4 is attached to this rod portion 43a.
8 to the rotor 44. pole bearing 4
8 is slidable with respect to the rod portion 43a, and is installed in a spherical attachment hole 44a provided in the rotor 44 so as to be tiltable. The rotor 44 is a member 44A that can be divided into upper and lower halves connected by four bolts 44C.

44B, and is rotatably assembled to the housing H via a pair of bearings 55 and 56.
It has sector teeth 44b that mesh with rack teeth 30a formed on one side of the actuating rod 30. In addition, both bearings 55.
The play in 56 is due to the holder H attached to the housing H.
It can be eliminated by screwing a (fixed by Rosokunaso 1-Hb).

Therefore, in the above-mentioned coupling mechanism A, ■the input shaft 4
1 is assembled via a ball spline 45 to a conical crankshaft 42, and a connecting body 4 is attached via bearings 53 and 54.
3 and the ball nut 47.

■ Spherical mounting hole 44 provided in the upper member 44A of the rotor 44
Assemble the pole bearing 48 to a.

■The one assembled in the above and the one assembled in the above ■,
The rod portion 43a of the connecting body 43 is fitted into the ball bearing 48 while being combined.

(2) Connect the lower member 44B to the upper member 44A of the rotor 44 with a bolt 44C so that the shaft portions supported by bearings 55 and 56 are coaxial.

■The bearing 52 assembled in the steps up to ■ above.
and the operating condo 30, etc., are assembled into the housing H formed in advance.

(2) After the bearing 56 is assembled and fixed with a snap ring, the bearing 55 is assembled and temporarily tightened with the holder Ha.

■Install the bearing 51 and secure it with a snap ring.

■Place the rear cover He on the ball nut 47 in the neutral position.
The rear cover HC and the ball nut 47 are connected by bolts Hd, and the rear cover HC is connected to the housing H by bolts He.

■Finally, fix the holder Ha with the lock nut Hb and attach the camp Hf to the housing H.

Conical crankshaft 42. Connector 43
．． Rotor 44. Each member such as a ball nut 47 is assembled within the housing H.

The link mechanism B is shown in FIGS. 3 and 5r! ! As shown in J, an actuation rod 30, a relay rod 71 provided through the actuation rod 30, and a tie rod door 2 connected to both left and right ends of the relay rod 71 via ball joints.
．． 73, and knuckle arms 74.75 connected to each tie rod 72.73 via a ball joint, so that the rear rain wheel WR is steered by displacement of the knuckle arms 74.75 in the left-right direction. It has become.

In addition, each end of the housing H and each tie rod 72°73
The insides of the boots 76 and 77, both ends of which are fixed to the ends of the relay rods 76 and 77, are connected by pipes 78 so that the left and right movement of the relay rod 71 is not inhibited.

The relay rod 71 includes a tenth rod 71A that passes through the actuating rod 30 and has both ends protruding from the actuating rod 30, and a second rod 71A that is connected to both left and right ends of the tenth rod 71A by clipping.
0th hand 71B and 30th hand 71C, and each rod door 1B
, 71C locking nuts 71D, 71
'E, its length can be adjusted, and it is supported slidably in the axial direction by bearing bushes 61 and 62 assembled to the housing H.

A socket 71b1 that forms a ball joint with the spherical end 73a of the tie rod 73 is integrally formed at the outer end of the 20th node 71B. Further, a spring 31 and a pair of left and right flanged sleeves 32, 33 are interposed between the relay rod 71 and the actuating rod 130, and the relative axial movement of both rods 30, 71 is elastically controlled by a predetermined amount. It is meant to be transmitted.

The power steering mechanism C assists the force transmitted from the operating rod 30 to the relay rod 71, and the power steering mechanism C
I, power cylinder 02, etc. The control valve C1 is a spool type control valve, and the operating rod 30
The valve sleeve 34 is fitted and fixed therein, and the valve spool 71a1 is formed in a part of the tenth node 71A of the relay rod 71.
The supply board 1-7182 formed in 1 is connected to the 10th node 71
The through hole (not shown) provided in A and the through hole 71b2 provided in the 20th node 71B communicate with the inlet bow 71b3 provided in the 20th node 71B, and the valve spool 71a1
Both discharge ports 1-71a3 formed in the 10th node 71
A through hole provided parallel to and separate from the aforementioned through hole (not shown)
A through hole 71a4 extending radially outward from the end of the same through hole and a through hole 71b4 provided in the 20th node 71B pass through the 20th node 71b4.
It communicates with an outflow boat 71b5 provided in the end 71B. Note that the inflow port 71b3 is connected to the hydraulic pump P, and the outflow port 71b5 is connected to the reservoir T.

On the other hand, the power cylinder C2 includes a cylinder body Hg constructed using a part of the housing H, and a cylinder body Hg constructed using a part of the housing H.
A pair of left and right oil chambers R1 are fitted into the interior so as to be slidable in the axial direction.
, R2, and the piston 71C1 is fixed onto the 30th node 71C of the relay rod 71. The oil chamber R1 on the left side of FIG.
The left port 71a6 in FIG. 3 is formed in the valve spool 71a1 through the through hole 71-85 provided in the zero end 71A.
The oil chamber R2 on the right side of Fig. 3 is connected to the 30th node 7.
It communicates with the right side port 71a8 in FIG. 3 formed in the valve spool 71al through a through hole 71c4 provided in the 1C and a through hole 71a7 provided parallel to and separate from the through hole 71a5 in the tenth tube 71A.

In this embodiment configured as described above, when the steering wheel WS is rotated, the rank par 1) is displaced in the left-right direction, and the front wheels WF are steered. During this steering, the rotating shaft 20 is rotated by the rack par 1), the input shaft 41 in the coupling mechanism A is rotated, the conical crankshaft 42 is rotated, and at the same time it is moved in the axial direction by the ball screw mechanism. Therefore, the connecting body 43 assembled on the pin portion 42a of the conical crankshaft 42 is
As illustrated in FIG. 6 (when the conical crankshaft 42,090 rotations) and FIG. 7 (when the conical crankshaft 42 rotates 180 degrees to the right), the conical crankshaft 42 swings in accordance with the rotation of the conical crankshaft 42, and the conical The ball bearing 48 moves in the axial direction in response to the axial movement of the crankshaft 42, and the two movements of the rocking and axial movement of the connecting body 43 are combined.
and is transmitted to the actuating rod 30 via the rotor 44.

Therefore, the actuating rod 30 moves in the axial direction in response to the above-mentioned combined movement by an amount shown by the solid line in FIG. and the amount of movement obtained by the axial movement of the connecting body 43 shown by the two-dot chain line), and when the front wheel WF has a small steering angle, it moves to the same phase side to a small extent, and the front wheel WF When the steering angle is large, the rear wheels WR are largely steered to the opposite phase side. Note that the movement of the actuating rod 30 is transmitted to the relay rod door 1 via the spring 31 and the like, and also brings about the operation of the power cylinder mechanism C, so that the rear wheel WR is steered while being assisted by the power cylinder mechanism C.

Therefore, in this embodiment, the amount of feed per rotation of the conical crankshaft by the ball screw mechanism (thread groove 42
By appropriately setting the inclination angle θ of the bin portion 42a of the conical crankshaft 42 (determined by the lead of c), the axial direction of the actuating rod 30 obtained by the rotation of the conical crankshaft 42 can be adjusted. The displacement can be set appropriately, and the rear wheel steering angle relative to the front wheel steering angle can be set in accordance with the characteristics of the vehicle, which varies depending on the vehicle type.

By the way, in this embodiment, the feed amount by the above-mentioned ball screw mechanism and the inclination angle θ of the pin portion 42a of the conical crankshaft 42 can be adjusted without being subject to any manufacturing restrictions even within a limited space. Since each can be set steplessly as appropriate, it is possible to extremely easily set the optimum rear wheel steering angle within a limited space to suit the characteristics of different vehicles.

In addition, in this embodiment, in setting the neutral position where the steering angle of the rear wheel is zero, the coupling body 43° ball bearing 48
．． After setting only the rotational direction position of the conical crankshaft 42 with the rotor 44 etc. assembled in advance with respect to the housing H to the set position, the sector teeth 44b of the rotor 44 are engaged (connected) with the rack teeth 30a of the operating rod 30. By the way,
It is extremely easy to assemble and can be manufactured at low cost.

In this embodiment, since the power steering mechanism C is disposed closer to the rear wheel WR than the coupling mechanism A, when the relay rod 71 is pushed in the axial direction by an external force from the rear wheel WR, the control valve C1 is closed. The power cylinder C2 is operated so as to generate a force opposing the external force. Therefore, the external force is canceled and the rear wheel steering device is not operated by the external force.

9 and 10 show a second embodiment of the rear wheel steering device according to the present invention. In this embodiment, a conical crankshaft 42A is connected to the front shaft via a ball screw mechanism. It is assembled to the housing H, and is also rotatably and slidably assembled to the housing H via the bearing bush 59 at the rear shaft portion, and is rotatable and movable in the axial direction with respect to the housing H. It is possible. Further, in this embodiment, the conical crankshaft 42A
is directly connected to the rear intermediate shaft of the rotating shaft 20 (corresponding to the intermediate shaft 23 of the first embodiment), and the intermediate shaft has a spline fitting portion in the intermediate portion that allows axial movement. It is composed of two axes. Since the other configurations are substantially the same as those of the first embodiment, the same reference numerals are given and the explanation thereof will be omitted. Furthermore, since the operation of this second embodiment is substantially the same as that of the first embodiment, a description thereof will be omitted.

(Modification) In the above embodiment, a ball screw mechanism was used as a shaft feeding mechanism that moves the conical crankshaft in the axial direction when the conical crankshaft rotates, but other types of shaft feeding mechanism may be used. , for example, a cam (1) as shown in Figure 1).
A shaft feeding mechanism using a cam follower (a pin provided integrally with the conical crankshaft 42) 81 and a cam follower (a pin provided integrally with the conical crankshaft 42) may also be used.

Further, in the above embodiment, the rotating shaft 20 that rotates in response to the steering operation of the front wheel WF is connected to the rack par 1) of the front wheel side steering link mechanism.
However, the rotating shaft 20 is connected to a steering main shaft that is directly rotated by the steering wheel WS, and the rotating shaft 20 is rotated by the steering main shaft. is also possible.

Further, in the embodiment described above, the actuation rod 30 and the relay rod 71 are configured as separate members so as to be movable relative to each other in the axial direction, and the power steering mechanism C is disposed coaxially with both rods 30 and 71. It is also possible to integrate the rods 30, 71 and eliminate the power steering mechanism C.

[Brief explanation of the drawing]

1 to 8 relate to a first embodiment of the rear wheel steering device according to the present invention, FIG. 1 is an enlarged longitudinal sectional side view taken along line 1-I in FIG. 3, and FIG. 1 is a partially cutaway plan view of the part shown in FIG. 1, FIG. 3 is a longitudinal sectional front view of the rear wheel steering device, FIG. 4 is a plan view of the same, and FIG. 5 is an example of a vehicle equipped with the rear wheel steering device. A schematic plan view, FIGS. 6 and 7 are operational explanatory diagrams of the main parts of the rear wheel steering device, and FIG. 8 shows the rotation angle of the conical crankshaft and the axis of the operating rod obtained by the rear wheel steering device. FIG. 3 is a diagram showing a relationship between directional displacement amounts. 9 and 10 relate to a second embodiment of the rear wheel steering device according to the present invention, FIG. 9 is an enlarged vertical sectional side view of the main part, and FIG. 10 is a cutaway view of the same part. be. Also, the first
) is a partial sectional view showing a modification of the shaft feeding mechanism of the rear wheel steering device according to the present invention. Explanation of symbols 10... Front wheel side steering link mechanism, 20...
Rotating shaft, 30... Operating rod, 30a... Rank tooth, 42... Conical crankshaft, 42a... Pin portion, 42C... Thread groove, 43... Connecting body, 43a...
・Rod part, 44... Rotor, 44b... Sector tooth, 46... Ball, 47... Ball nut, 48...
...Ball bearing, A...Connection mechanism, B...Rear wheel side steering link mechanism, D...Ball screw mechanism (shaft feed mechanism), H...Housing, Ll...Conical crankshaft Axis line, Ws...Steering wheel, W
F...Front wheel, WR...Rear wheel.

Claims (3)

[Claims] (1) A rotating shaft that rotates in response to the steering operation of the front wheels is connected to an operating rod of the rear wheel side steering link mechanism, and the operating rod is displaced in its axial direction in accordance with the rotation of the rotating shaft, thereby steering the front wheels. A rear wheel steering device for a front and rear wheel steered vehicle comprising a coupling mechanism that steers the rear wheels to the same phase side when the steering angle is small and steers the rear wheels to the opposite phase side when the front wheels have a large steering angle. The mechanism is rotatably and axially movably assembled in the housing via a shaft feed mechanism, is connected to the rotating shaft, and has a pin portion inclined at a set angle with respect to the axis in an intermediate portion, and the shaft feed mechanism It has a conical crankshaft that is moved in the axial direction by a mechanism, and a rod part that is rotatably assembled on the pin part of the conical crankshaft and extends in the radial direction of the pin part, and the rod part is used to perform the operation. A rear wheel steering vehicle for a front and rear wheel steering vehicle, characterized in that the connecting body is connected to a rod via a conversion mechanism and swings by rotation of the conical crankshaft to displace the operating rod in its axial direction. Device. (2) A ball screw mechanism in which the shaft feeding mechanism includes a thread groove formed on the outer periphery of the shaft portion of the conical crankshaft, and a ball nut that is fixed to the housing and accommodates balls that are circulated and supplied to the thread groove inside. A rear wheel steering device for a front and rear wheel steered vehicle according to claim 1. (3) The conversion mechanism includes a rotor that is rotatably assembled to the housing and has sector teeth that mesh with rack teeth formed on one side of the actuating rod, and that displaces the actuating rod in its axial direction by rotation. and a ball bearing that is tiltably assembled to the rotor while being fitted onto the rod portion of the connecting body, and rotates the rotor by the swinging of the rod portion. A rear wheel steering device for a front and rear wheel steered vehicle according to claim 1 or 2.