JPH03178882A - Rear wheel steering device of front-rear wheel steering vehicle - Google Patents

Abstract

PURPOSE:To reduce a mechanical maximum movable steering angle degree of a rear wheel in accordance with a car speed by providing the second drive means, which moves the first drive means for turning an eccentric cam member and a shaft member along a moving axial line orthogonal with an axial line, in a housing. CONSTITUTION:When an eccentric cam member 50 is turned for housing by the first drive means 63, a lever member 30, engaged with this eccentric cam member 50 in a position eccentrically placed from a turn axial line, performs a swivel motion about it in accordance with a turn amount of the eccentric cam 50. The swivel motion of this lever member 30 is converted into a linear motion in which an operating rod 20, whose one end is turnably engaged, is moved along an axial line. Then, when a shaft member is moved relatively to the housing along a moving axial line, orthogonally intersecting with the axial line of the operating rod 20, by the second drive member 43, that is, lever ratio of the lever member is in a predetermined value, the operating rod is moved in accordance with this predetermined lever ratio to steer a rear wheel.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a rear wheel steering device for a front and rear wheel steered vehicle that steers the rear wheels of the vehicle in response to the steering operation of the front wheels.

[Prior Art J] Conventionally, various types of rear wheel steering devices for front and rear wheel steered vehicles have been proposed. For example, JP-A-63
Publication No. 207773 discloses a rear wheel steering device that uses one electric motor and a ball screw mechanism for rear wheel steering, and obtains a predetermined rear wheel steering amount by operating the electric motor in response to front wheel steering. It is shown.

[Problems to be Solved by the Invention] However, in the conventional rear wheel steering device using one electric motor, the vehicle speed, the steering direction and amount of steering of the front wheels are electrically detected, Since it is necessary to control the direction and amount of rotation of the electric motor to obtain the steering direction and amount of steering for the rear wheels, extremely high precision control is required. This is because there is no mechanical communication between the front wheels and the rear wheels, and the rear wheels can be steered independently, so if the electric motor goes out of control due to a malfunction in the control system, the rear wheels will be steered by themselves, causing the vehicle to This is because there is a risk of unexpected behavior. For example, when a vehicle is traveling at high speed, if the rear wheels are steered to a large steering angle, the vehicle may spin, causing extremely dangerous vehicle motion.

The purpose of the present invention is to focus on such conventional problems, and to reduce the mechanical maximum movable steering angle amount of the rear wheels according to the vehicle speed,
The object of the present invention is to provide a rear wheel steering device suitable for avoiding the above-mentioned dangerous vehicle movement.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a housing that movably supports an actuation rod that steers a rear wheel during movement along its axis, and a housing that has one end connected to the actuation rod. The engaged lever member moves the housing perpendicularly to the axis! a shaft member that is provided movably along line 1iIII and that engages to give the lever member a rotational axis perpendicular to the axis and the axis of movement; an eccentric cam member that engages in position; a first driving means provided on the housing for rotating the eccentric cam member; and a first driving means provided on the housing for moving the shaft member along a movement axis perpendicular to the axis. A second driving means.

[Function] According to the present invention, when the eccentric cam member is rotated with respect to the housing by the first driving means, the eccentric cam member rotates! The lever member engaged at a position deviated from the l1Jll@ line performs a rocking motion about its rotation axis in accordance with the amount of rotation of the eccentric cam. This swinging motion of the lever member is
One end thereof is converted into a linear motion that moves the rotatably engaged actuating rod along the axis.

At this time, if the shaft member is moved by the second driving means relative to the housing along a movement axis perpendicular to the axis of the actuating rod, in other words, if the lever ratio of the lever member is at a predetermined value, The actuating rod moves in accordance with this predetermined lever ratio, and the rear wheels are steered. Therefore, if the movement of the shaft member is the maximum amount along the line, i.e. if the lever ratio is at the maximum allowable amount, then the maximum displacement of the actuating rod will be given, and if the lever ratio is zero, then the actuating rod will be The displacement of becomes zero. Therefore, for example, if the second drive means is drive-controlled in accordance with the vehicle speed, the maximum mechanically movable steering angle amount of the rear wheels can be reduced in accordance with the vehicle speed.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings.

An embodiment of the present invention is shown in FIGS. 1 and 2'.

In the figure, IO is a housing that is attached to the vehicle body, and has a seventeenth body part 108 and a second body part 10B that is fixed to the first body part + OA. It is provided with a protruding leg cylinder portion (not shown). The leg cylinder has bearing 1
2, 12 to move the actuating rod 20°20 along its axis L1.
It is supported so that it can be moved along. In addition, the second main body part 1
One end of 0B is covered with a lid 10G. The inner ends of the operating rods 20, 20 are connected to the center block 20A in which the engagement holes 20B are provided, and both station ends are connected to tie rods via ball joints (not shown) to steer the rear wheels. ing.

Reference numeral 30 denotes a lever member in which a pin portion 30A drilled at one end thereof is rotatably engaged with an engagement hole 20B provided in the center block 2OA of the actuating rods 20, 20 via a needle bearing 30B. In this embodiment, a slot 30C is formed on the other end side, or a long groove 30D is formed on the back side facing the pin portion 30.

40 is a needle bearing 40 in the long groove 300.
It is a shaft member equipped with a shaft portion 40A that is slidably engaged through B, and a threaded hole 10G is formed in the center.

The threaded hole 40G has a bearing 41 at both ends attached to the first main body 10A of the housing 10 and the screwed body 100, respectively.
．． A screw shaft 42 supported by 41 is screwed together.

The axis of the screw @42 is the same as the working lot 20.20'm mentioned above.
The movement axis L2 is set perpendicular to the line .

This screw @42 is connected to the second motor 43 fixedly attached to the first main body 10A, and the output l of the motor 43 is
It is driven via a gear 44 fixed to the l11438 and a gear 428 integrally formed to the screw shaft 42.

As a result, the lliIh member 40 moves up and down along the movement axes 1 and 2 as the second motor 43 rotates.

Therefore, these, the second motor 43, each gear 44° 42
A and the screw @42 constitute a second driving means.

Further, the axis of the shaft portion 40A of the shaft member 40 is the axis L1 of the aforementioned working loft 20.20 and the movement axis 1 of the shaft member 40.
．． 2, the rotation axis L3 of the lever member 30 is given.

50 is a rotation axis L3 in the slot 30C of the lever member 30.
The eccentric cam member 50 is provided with an eccentric pin 50A that is slidably engaged via a needle bearing 508 at a position offset from the center of the shaft. It is rotatably supported via 51.51.

Furthermore, 60 is a worm wheel that is coupled to the eccentric cam member 50 by press fitting or the like, and is meshed with a worm wheel 62 that is driven by a first motor 63 that is fixed to the second main body portion 10B of the housing IO.

Thus, the first motor 63, the worm binion 62, and the worm wheel 60 constitute a first driving means.

Next, the operation of this embodiment having the above configuration will be explained with reference to FIG.

First, when the second motor 43 rotates the screw shaft 42 via the gears 44 and 42A, the shaft portion 40A of the shaft member 40 that meshes with the screw shaft 42 moves along the axis L2 of movement relative to the housing IO within the long groove 30D of the lever member 30. Move relative to the direction.

In this state of relative movement between the shaft member 40 and the lever member 30, when the worm binion 62 is rotated by the first motor 63, the eccentric cam member 50 is also rotated via the worm wheel 60 that meshes with the worm binion 62. The eccentric pin 50A slides within the slot 30C of the lever member 30.

Then, with the pin portion 30^ at one end, the operating loft 20
．． 20 is connected to the engaging hole 2OB of the central block 20A.
The lever member 30 that is engaged with the lever member 30 swings about the rotation axis L3 of the shaft portion 40A of the shaft member 40.

At this time, the shaft member 40 is driven by the second motor 43.
There is no relative movement between the lever member 30 and the lever member 30, as shown in FIG. 3(A).
As shown in , the center of the pin member 30A and the rotational axis L3 overlap, in other words, the shaft portion 40 with respect to the distance tit ao along the movement axis L2 between the eccentric pin 50A and the shaft portion 40A.
Distance II between A and pin member 30A! When the ratio of td+, that is, the lever ratio d+/do is zero, the circular motion of the eccentric cam 50 slides within the eccentric pin 508 or the slot 30C, and the center of the lever member 30 or pin member 30A, that is, the rotation I
It only swings around the rIIIl line and is not transmitted to the central block 20A. That is, the displacement of the actuating rod 20 is kept at zero.

However, in the above-mentioned state 5, as a result of the movement amount d of the shaft member 40 along the movement axis L2, the above-mentioned lever ratio is in the state of di/do "F 1" as shown in FIG. 3(B). Sometimes, the circular movement of the eccentric bin 50^ results in a movement via the lever member 30 in a direction along the axis RI corresponding to the lever ratio IL/do of the central block 2OA.

Therefore, when this amount of movement d is the maximum allowable amount of movement of the shaft member 40, the maximum lever ratio is obtained and the maximum displacement of the operating wood 20 is obtained.

However, the amount of movement d of the shaft member 40 along the movement axis L2,
If is a predetermined ratio of this maximum allowable movement, then (Ω
The circular movement to the 6-bin 50 is only possible in proportions corresponding to this proportion of the central block 2OA, and therefore of the actuating rod 2.
It is not converted to a displaced position along the zero axis L1.

In this way, the maximum value of the displacement position of the actuating rod 20, that is, the amount of steering angle of the rear wheels, is mechanically limited by changing the lever ratio.

When incorporating the above-mentioned rear wheel steering device into an actual vehicle,
For example, the steering direction and amount of steering of the front wheels may be detected by a steering angle sensor, the vehicle speed may be detected by a vehicle speed sensor, and predetermined control may be performed by a microcomputer or the like. At this time, the second motor 43 is controlled by 1 lilJ to give the maximum amount of steering angle of the rear wheels in accordance with the vehicle speed, and the first motor 63 is controlled to give the maximum amount of steering angle of the rear wheels in accordance with the steering direction and amount of steering of the wheels. , are controlled to provide a predetermined amount of steering angle that is in phase or out of phase. Therefore, if the rotation of the second motor is controlled so that the maximum steering angle amount of the rear wheels, that is, the displacement amount of the actuating rod 20 becomes smaller as the vehicle speed increases, for example, the first motor 6j Even if the control system malfunctions and the first thousandth motor 63 rotates beyond the predetermined amount of steering angle to the rear wheels, the mechanical maximum amount of steering angle of the rear wheels is still limited. Therefore, when driving at high speed, the rear wheels may be steered indiscriminately.1. (It is Ino. Of course, the control system of the 2,000th, 43rd
If it is B, a malfunction in the control system of the 3rd (s, H-) taro 3 is detected, and the lever ratio of the second motor 43 shown in FIG. It is possible to control it so that it returns to the state where it is not present.

[Effect of the invention] As is clear from the above explanation, according to the present invention, the first
The lever member is swung around the rotation axis by the eccentric cam member driven by the drive means, and the lever ratio of the lever member is changed by moving the shaft member along the movement axis and moving the rotation axis by the second drive means. By changing the conversion rate of the operating wood into linear motion, the maximum mechanically movable steering angle of the rear wheels can be reduced in accordance with the vehicle speed, and dangerous vehicle motion can be avoided when driving at high speeds. A rear wheel steering device can be obtained.

[Brief explanation of drawings]

Fig. 1 is a side sectional view showing an embodiment of the present invention, Fig. 2 is a perspective view of the embodiment of the invention excluding the housing, and Fig. 3 is a main part for explaining the operation of the embodiment of the invention. It is a rear view. IO...Housing, 20...Operating rod, 208...Central block, 20B...Engagement hole, 30...Lever member, 30^...Bin part, 30G...Slot , 300...Long groove, 40...Shaft member, 40A...Shaft portion, 42...Screw shaft, 43...Second motor, 50...Eccentric cam member, 50A...Eccentric bin , 60...Worm wheel, 62...Worm binion, 63...First motor...axis line, 1.2...movement axis line, L3...rotation axis line.

Claims (1)

[Scope of Claims] 1) a housing that supports an actuation rod movably along its axis for steering a rear wheel during movement; a lever member having one end engaged with the actuation rod; a shaft member that is movable along a movement axis perpendicular to the axis and engages to provide the lever member with a rotation axis perpendicular to the axis and the movement axis; an eccentric cam member that engages at a position offset from the housing; a first drive means that is provided on the housing and rotates the eccentric cam member; and a first drive means that is provided on the housing that rotates the shaft member on a movement axis perpendicular to the axis. A rear wheel steering device for a front and rear wheel steered vehicle, comprising: a second drive means for moving along the front and rear wheels.