JPH04123984A - Rear-wheel steering system for truck, etc. - Google Patents

Abstract

PURPOSE:To improve the extent of steering stability at time of running at high speed by supporting a central part of a rear axle housing pivotally on a top part of a V-shape radius rod, and suspending each spot at both ends on an undercarriage frame via a laminated sparing gear constituted so as to make sprung load act in the suspending direction. CONSTITUTION:A top part of a V-shaped upper radius rod 54 set up along a center line in the longitudinal direction of a car body is pivotally attached to the upper side of a differential casing 58 installed in the central part of a rear axle housing 16 via a ball joint unit 56, and both leg ends of he housing 16 is pivotally attached to a side rail 12 of an undercarriage frame 10. This rear axle housing 16 is steered and rotated by a hydraulic cylinder unit 76 via a lower radius rod 66. In addition, each of laminated spring gears 20, 28 are interposed between the rear axle housing 16 and the undercarriage frame 10, and the spring gear 20 is connected to the frame 10 of its longitudinal end so as to make sprung load act in the suspending direction each via a rocker link 22.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rear wheel steering device for a vehicle, particularly a truck.

(Prior Art) In recent years, various four-wheel steering systems and devices have been proposed in which rear wheels are steered in conjunction with front wheel steering in order to improve steering stability during high-speed driving.

However, all conventional four-wheel steering devices are related to vehicles in which the front and rear wheels are independently suspended, mostly passenger cars, and vehicles in which the rear wheels are supported within a rigid shaft tube or rear axle housing. In particular, a four-wheel steering device such as an L-rack that uses double tires on the rear wheels has not yet been proposed.

(Problems to be Solved by the Invention) The present invention provides a novel and useful rear wheel that can improve the steering stability during high-speed running in a truck or the like in which the rear wheel is supported by both end portions of the rear axle housing in the vehicle RLJ direction. The object of the present invention is to provide a steering device.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a chassis frame, a rear axle housing that supports rear wheels at both ends in the vehicle width direction, and an interposed body between the rear axle housing and the chassis frame. The laminated leaf spring device is arranged along the center line in the longitudinal direction of the vehicle body, and its apex is pivotally connected to the center portion of the rear axle housing in the vehicle width direction, and the free end portions of both legs are respectively pivotally connected to the chassis frame. a pair of left and right lower radius rods, which are arranged approximately symmetrically on both sides of the longitudinal center line of the vehicle body and whose respective ends are pivotally connected to the rear axle housing; They are respectively connected to the other ends of the radius rods, and are activated when the vehicle is steered to drive the left and right lower lanois rods in opposite directions, thereby moving the rear axle housing songs above.
It is equipped with a pair of rear wheel steering actuators that rotate around the apex pivot point of the three-way radius rod, and the above-mentioned stacked leaf spring device suspends the sprung load at its front and rear ends via swing links, respectively. The trunk is connected to the chassis frame so as to act in the direction, and the rear axle housing and the stacked leaf spring device are connected so as to be relatively rotatable around a pin or pivot provided in the vertical direction. This paper proposes a rear wheel steering system for vehicles such as the following.

(Function) According to the present invention, the rear axle housing has its center portion in the vehicle width direction pivoted to the apex portion of the figure-7-shaped upper radius rod, and the vicinity of both ends in the vehicle direction directed to the chassis frame by air springs. Since it is suspended, it can rotate around the apex pivot point of the upper Lanoas rod, in other words, it becomes possible to steer the rear wheels. The steering movement of the rear axle howsong is controlled by a pair of rear wheel steering actuators that operate in opposite directions a pair of left and right lower and sear slots whose respective ends are pivotally connected to the rear axle howsong.

In addition, the front and rear ends of the stacked leaf spring device are connected to the chassis frame via swing links, so that the spring load acts in the hanging direction, so the rear axle howsong is placed in the neutral position when driving straight. Furthermore, since the rear axle housing and the stacked leaf spring device are connected to the periphery of the pin or pivot so that they can rotate relative to each other, both ends of the stacked leaf spring device can be easily held during steering. Displacement in the width direction of the vehicle is reduced, allowing smooth steering.

(Example) Examples of the present invention will be specifically described below with reference to the accompanying drawings. Reference numeral 10 in the figure is a chassis frame of a vehicle such as a truck, which includes a pair of left and right sight rails 12 extending in the longitudinal direction of the vehicle body, and a pair of sight rails 12 extending in the vehicle width direction. It is composed of a plurality of cross members 14.

Reference numeral 16 denotes a main leaf spring pivotally mounted at both end portions in the vehicle width direction to support the double tires 18. As clearly shown in the sectional view of FIG. 3, the lower ends of the links 22 are pivotally connected to brackets 28 by pins 26, and the brackets 28 are fixed to the sight rails 12 of the chassis frame 10.

A helper spring 30 is disposed above the main leaf spring 20 and whose front and rear end portions slide into contact with a helper toe 32 mounted on the sight rail 12 when the vehicle load exceeds a set load.

As clearly shown in the enlarged exploded view of FIG. 4, the upper surface of the end of the rear axle housing 16, which faces the lower surface of the main leaf spring 20, is made of a highly wear-resistant material such as a high-Mn steel plate. A plate 34 is fixed by welding or the like, and a fitting hole 36 having a diameter d2 is bored in the sliding plate 34. An upper substrate 38 is interposed between the sliding plate 34 and the lower surface of the main leaf spring 20.
A sliding plate 40 similar to the sliding plate 34 is fixed to the lower surface of the sliding plate 8, and a pin or pivot 42 that fits into the fitting hole 36 is arranged downward in the center of the sliding plate 40. has been done.

A rubber bushing 44 is fixed to the outer periphery of the pin 42, and the outer diameter d1 of the rubber bushing core is equal to or smaller than the inner diameter d2 of the fitting hole 36. Further, a lower base plate 46 is disposed below the rear axle housing 16 and cooperates with the upper base plate 38, and a rubber node 48 is fixed by baking to the upper surface of the lower base plate.

Between the upper substrate 38 and the lower substrate 46, a plurality of (usually 4) spacers 50 made of .
By inserting and tightening the U-bolt 52 into the spacer 50, the required compressive force is applied to the rubber pad 48, and while the sliding plates 34 and 40 are brought into pressure contact, the rear axle housing 16 is moved to the main leak j7°. 20 and Hertz 9 leaf spring 30. (In the illustrated embodiment, the stacked leaf spring device for rear wheel suspension is composed of a main leaf spring 20 and a helper leaf spring 30.
7 spring 30 may be omitted. ) An upper radius rod 54 having a figure 7 planar shape is disposed between the sight rails 12 of the chassis frame 10 along the center line in the longitudinal direction of the vehicle body, and the apex of the radius rod is connected to a pole joint device 56 (or The rear axle housing 16 is
The free ends of both legs of the rod are connected to the chassis frame 10 via pole joint devices 60 (or equivalent rubber buttress type joint devices), respectively.
It is pivotally connected to the sight rail 12 (or crossmenu 14) of the.

As clearly shown in the side view of FIG. 2, brackets 62 are fixed to the side surfaces of the rear axle housing 16 near both ends in the vehicle width direction by welding or the like.
2, one ends of a pair of left and right lower radius rods 66 are pivotally connected to each other via a pole joint device 64 (or an equivalent rubber bushing one-type joint device). The other end of each lower radius rod 66 is pivotally connected via a pin 74 to the lower end of an actuating rod 72 which is pivotally supported by a pin member O to a bracket 68 fixed to the web or side wall of the site rail 12. There is. Further, a piston shaft 78 of a hydraulic cylinder device 76 forming a pair of left and right rear wheel steering actuators is pivotally connected to the upper end of the operating lever 72 by a pin 80, and a cylinder 82 of the hydraulic cylinder device is connected to the above-mentioned cylinder by a pin 84. It is pivoted to the web or sidewall of the sight rail 12.

The specific construction of the pole joint devices 56, 60 and 64 is illustrated in FIGS. 6 and 7. First, in FIG. 6, reference numeral 86 indicates one member that causes relative rotational displacement, that is, the upper radius rod 54 or the lower radius rod 66, and 88 indicates the other member, that is, the rear axle housing 16 or the bracket 62. The other member 88 supports a shaft 92 having a spherical member 90, and the one member 86 supports a ball seat 94 that abuts the spherical member 90. With this configuration, one member 86 can freely rotate relative to the other member 88 within a plane perpendicular to the axis of the shaft 92 and within a plane including the coaxial line.

Further, in the pole joint device shown in FIG. 7, a housing 100 for accommodating the ball head 98 of the pole stud 96 is formed on one member 86, that is, the upper radius rod 54 or the upper radius rod 66. 1
Ball seats 102 and 104 that abut the ball head 98 are interposed within the ball head 98, and the gill stud 96 is fixed to the other member 88, that is, the rear axle housing 16 or the bracket 62. With this configuration as well, one member 86 can freely rotate relative to the other member 88 within a plane perpendicular to the axis of Solstad 96 and within a plane including the coaxial line.

Furthermore, FIG. 8 shows a rubber bush type joint device which is functionally almost the same as the ball joint device described above. A rubber bushing 106 is fixed by firing to the end of one member 86 similar to that shown in FIG. 6, and a spherical member 9o is fixed by firing to the inner periphery of the rubber bushing 106 at the same time. A shaft 92 supported by the other member 88 similar to the above is inserted through the spherical member 9o. Also in this configuration, relative rotation is allowed between the one member 86 and the other member 88 in a plane perpendicular to the axis of the shaft 92 and in a plane including the axis.

Finally, FIG. 9 is a conceptual diagram of a device for controlling the operation of the rear wheel steering actuator 76.

In the figure, reference numeral 108 is a steering angle sensor of the optical pulse non-contact type that is installed on the steering shaft 110 to detect the steering angle, 112 is a vehicle speed sensor, 114 is a yaw rate sensor, and 116 is a steering angle signal from the steering angle sensor 108. A controller 120 is a hydraulic pump that receives a vehicle speed signal from the vehicle speed sensor 112 and a turning signal from the yaw rotation sensor 1140 to control the control valve 118 that operates the rear wheel steering actuator 76.

When the vehicle is traveling at high speed, when the steering wheel 122 is operated and the front wheels 124 are steered, a steering angle signal from the steering angle sensor 108, a vehicle speed signal from the vehicle speed sensor 112, and a turning signal from the yaw rate sensor 1]4 are output. The controller 116 that receives this outputs a drive signal to the control valve 118, thereby operating the control valve. The high pressure hydraulic oil discharged from the hydraulic pump 120 by the operation of the control valve 118 is supplied to the pair of rear wheel steering actuators 76 .
The actuators operate in opposite directions, that is, when one of the left and right actuators expands, the other actuator contracts.

When steering the rear wheels for the purpose of improving steering stability when the vehicle is running at high speed, the rear wheels 18 are usually steered by a small steering angle, for example, about 1 to 5 degrees, in the same direction as the steering direction of the front wheels 124. . However, in connection with the steering of the front wheels 124, the rear wheels 18 are first steered by a slight angle in the opposite direction to the steering direction of the front wheels 124, and after an instant, the rear wheels 18 are steered by a slight angle in the same direction as the steering direction of the front wheels 124. It is also possible to employ a rear wheel steering system that steers the vehicle.

In the above configuration, the cylinder 82 of the hydraulic cylinder device 76 forming the rear wheel steering actuator has a built-in stopper that limits the extension and contraction strokes of the piston shaft 78, and when the hydraulic cylinder device 76 is actuated, the stopper causes the rear axle housing 1 That is, the rear wheel 18 is provided so that it can be correctly steered by a preset small steering angle of 1 to 5 degrees, for example, 1 degree, and when the hydraulic cylinder device 76 is at rest, the built-in neutral spring is activated. Alternatively, by hydraulically locking (applying equal hydraulic pressure to both chambers of the piston to fix the piston in the neutral position), the piston shaft 78 is fixed in the neutral position, and the rear axle housing 16, that is, the rear wheel 18, is fixed in the neutral position. It is maintained in a straight line state with zero angle.1. Tenon leaf spring 20
Since both ends act in the hanging direction, there is an advantage that the rear axle housing 16 can be easily maintained neutrally.

When the front wheels 124 are steered while the vehicle is running at high speed, the control valve 118 is activated by a command from the controller 116 as described above.
is activated, causing the pair of rear wheel steering actuators 76 to operate in opposite directions. Piston shaft 7 of each actuator
The actuating levers 72 connected at one end to each of the actuating levers 8 rotate in opposite directions, and the lower radius rod 66 connected to the other end of the actuating lever 72 is driven toward the rear of the vehicle body. As a result, as shown in the schematic plan view of FIG. 5, the rear axle housing 16 rotates around the apex of the upper radius rod 540 forming a figure 7 shape by a set steering angle of 1 degree, for example, in either the left or right direction. This results in improved steering stability during high-speed steering in a manner well known in the art. When the rear axle housing 16 rotates for steering, the sliding plate 34t is fixed to the upper side of the rear axle housing, and the sliding plate 34t is fixed to the lower side of the upper base plate 38, which is fixed to the non-leaf spring 20 side. The sliding plate 4 rotates relatively around the tortoise, pin or pivot 42 with deformation in the radial direction of the rubber pusher 44, and is pressed against the lower surface of the rear axle housing 16 in a compressed state. The rubber knot 48 flexibly generates shearing deformation during the relative rotation between the lower base plate 46 fixed to the non-leaf spring 20 side and the rear axle housing 16, so that the chassis frame 10
The steering rotation of the rear axle housing 16 relative to the rear axle housing 16 is performed extremely smoothly.

Further, when the vehicle is traveling straight or turning during steering, the rear axle housing 16 moves up and down with respect to the chassis frame 10, of course, while the leaf springs 20 and 30 receive loads, and at this time, the rear axle housing 16
are the upper radius rod 54 and the lower radius rod 66
Performs parallel link movement up and down. Furthermore, the upper radius rod 54 is connected to the ball joint devices 56 and 60 (
The lower radius rod 66 is pivotally connected to the rear axle how song 16 and the undercarriage frame 10 by means of a similar pole/button type joint device).
Since it is pivotally connected to the rear axle housing 16 by a joint device 64 (or a rubber bush type joint device with the same effect), even if the rear axle housing 16 tilts from side to side or rolls when traveling on uneven roads or when turning, , its displacement is not hindered.

In addition, in the above embodiment, a vehicle with one rear axle is illustrated, but in the case of a vehicle with two rear axles, a rear wheel steering device similar to that described above may be provided on both the rear front axle and the rear axle. It will be done. Furthermore, in vehicles with two rear axles, one of the rear axles is often configured as a dead axle that does not transmit driving force, but the steering device itself is substantially the same as the case of the drive wheels illustrated.

(Effects of the Invention) As mentioned above, the vehicle rear wheel steering device according to the present invention includes a chassis frame, a rear axle housing that supports the rear wheels at both ends in the vehicle width direction, and a combination of the rear axle housing and the chassis frame. a stacked plate spring device interposed therebetween; the chassis frame is disposed along the longitudinal center line of the vehicle body, and its apex is pivotally connected to the center portion of the rear axle housing in the vehicle width direction; and the chassis frame is the free end portion of both legs. Upper radius rods having a figure 7 planar shape are pivotally connected to the upper radius rods, and a pair of left and right lower radius rods are arranged approximately symmetrically on both sides of the center line in the longitudinal direction of the vehicle body, and one end of the husband is pivotally connected to the rear axle housing. The radius rod is connected to the other end of the lower radius rod, and is actuated when the vehicle is steered to drive the left and right lower radius rods in front and back opposite directions to move the rear axle housing around the pivot point of the apex of the upper radius rod. A pair of rear wheel steering actuators are provided for rotation, and the stacked leaf spring device is connected to the chassis frame at its front and rear ends through swing links, respectively, so that a sprung load acts in a hanging direction. and the rear axle housing and the stacked leaf spring device are connected so as to be relatively rotatable around a vertically disposed pin or pivot, and the rear axle housing and the stacked leaf spring device are connected so as to be relatively rotatable around a vertically disposed pin or pivot, and the rear axle housing and the stacked leaf spring device are This is industrially useful because it can improve steering stability during driving.

Figure 2 is a side view of the rear wheel steering device shown in Figure 1, Figure 3 is a sectional view taken along the line ■-■ in Figure 2, and Figure 4 shows the rear axle housing and stacked plate in Figure 2. Fig. 5 is an enlarged exploded view of the connection part with the device, and Fig. 5 is a schematic plan view showing the behavior of the rear axle housing during rear wheel steering, Fig. 6 and Fig. 7.
The figures are cross-sectional views showing the specific structures of the ball joint devices 56, 60, and 64 in the apparatus shown in FIGS. 1 and 2, and FIG. 8 is the ball joint device shown in FIGS. 6 and 7. FIG. 9 is a sectional view of a rubber bush type joint device having substantially the same effect as the joint device, and a schematic configuration diagram of an operation control device for the rear wheel steering actuator set in FIG. 1.

10... Chassis frame, 12... Sight rail, 1
6... Rear axle housing, 20... Main leaf ring, 30... Helper leaf ring,
54... Upper radius rod, 56, 6Q and 64.
... Pole joint device, 66 ... Lower radius rod, 72 ... Actuation lever 76 ... Rear wheel steering actuator.

size fart

Claims (1)

[Claims] An undercarriage frame, a rear axle housing that supports the rear wheels at both ends in the vehicle width direction, a stacked leaf spring device interposed between the rear axle housing and the undercarriage frame, and a stacked leaf spring device arranged along the longitudinal center line of the vehicle body. an upper radius rod having a V-shaped planar shape, whose apex is pivotally connected to the center portion of the rear axle housing in the vehicle width direction, and whose free ends of both legs are pivotally connected to the chassis frame; A pair of left and right lower radius rods are arranged approximately symmetrically on both sides, and one end of each is pivotally connected to the rear axle housing, and each of the lower radius rods is connected to the other end of the lower radius rod, and is activated when the vehicle is steered. a pair of rear wheel steering actuators that drive the rear axle housing in front and rear opposite directions and rotate the rear axle housing around the apex pivot point of the upper radius rod; The rear axle housing and the stacked leaf spring device are connected to the chassis frame via a swinging link so that a sprung load acts in the hanging direction, and the rear axle housing and the stacked leaf spring device are arranged around a pin or pivot that is disposed in the vertical direction. A rear wheel steering device for a truck or the like, characterized in that the rear wheels are connected to each other so that they can rotate relative to each other.