JP2800611B2 - Rear wheel steering device for trucks - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear wheel steering device for a truck or the like.

[0002]

2. Description of the Related Art In recent years, various four-wheel steering systems and devices have been proposed in which the rear wheels are steered in conjunction with the steering of the front wheels in order to improve the steering stability during high-speed running. Conventionally, in a truck in which a rear wheel is supported on both ends of a rigid axle tube or a rear axle housing in a vehicle width direction and the rear axle housing is suspended on a chassis frame via a leaf spring device, the rear axle housing itself is used. The applicant has already proposed a rear-wheel steering device that rotates around a center of rotation provided on a center line in the vehicle longitudinal direction. (JP-A-4-
No. 123984)

In the above-mentioned rear wheel steering device, the rear axle housing is configured to rotate around the center of a ball joint device disposed at the apex of one end of a V-shaped upper radius rod during turning. Since the other end of the V-shaped upper radius rod is pivotally connected to the chassis frame via the same ball joint device, the structure is slightly complicated and the manufacturing cost is high, so the structure is simplified. It is desirable to reduce the manufacturing cost.

[0004] In the above-mentioned proposed rear wheel steering device, the rear axle housing is pivoted around the center of a ball joint device disposed at the apex of the upper radius rod at the time of steering, so that the rear axle housing is disposed laterally of the chassis frame. Since a pair of left and right hydraulic cylinder devices that operate opposite to each other are provided, there is a problem that the hydraulic cylinder device is structurally complicated including the pressure oil piping and the manufacturing cost and weight increase. Since the longitudinal force acts on the device, the hydraulic cylinder device must withstand not only the steering operation force of the rear wheels but also the above-described longitudinal force when traveling straight ahead, which further increases the size and weight and price. There is.

According to the present invention, a rear axle housing is supported at both ends in the vehicle width direction of a rear axle housing, and the rear axle housing is simple, inexpensive and lightweight in a truck or the like mounted on a chassis frame via a leaf spring device. It is an object of the present invention to provide a simple rear wheel steering device.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and comprises a chassis frame, a rear axle housing supporting rear wheels at both ends in a vehicle width direction,
Left and right leaf spring devices interposed between the rear axle housing and the chassis frame and extending in the vehicle front-rear direction, respectively, are disposed extending along the vehicle width direction line, and one end thereof is provided in the vehicle width of the rear axle housing. A lateral rod pivotally attached to the center portion in the direction and the other end pivotally attached to the chassis frame, respectively, and are disposed substantially symmetrically on both sides of a longitudinal centerline of the vehicle body, and each end is pivotally attached to the rear axle housing. A pair of left and right lower radius rods, a pair of left and right L-shaped levers pivotally supported on the chassis frame and having one ends pivotally attached to the other ends of the lower radius rods, respectively, are disposed extending in the vehicle width direction. A connecting rod whose both ends are pivotally connected to the other ends of the left and right L-shaped levers respectively, and which is supported by the chassis frame and connected to one of the L-shaped levers for high-speed running The left and right lower radius rods are driven in the opposite directions by rotating the other L-shaped lever through the same L-shaped lever and the connecting rod in response to the steering and steering of the vehicle in the above, and the rear axle housing is moved. A rear wheel steering actuator for rotating the lateral rod around the one end pivot point, and the leaf spring device is provided with a shackle link capable of swinging both front and rear ends thereof. A truck which is connected to a chassis frame and has an intermediate portion in the front-rear direction connected to the rear axle housing via upper and lower shallow U-shaped rubber pads sandwiching the rear axle housing from above and below. Etc. are proposed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. In the drawing, reference numeral 10 denotes a chassis frame of a vehicle such as a truck, which includes a pair of left and right side rails 12 extending in the vehicle longitudinal direction and a plurality of side rails extending in the vehicle width direction and having both ends fixed to the left and right side rails 12. And four cross members 14. Reference numeral 16 denotes a rear axle housing that supports a rear wheel 18 with a double tire at both ends in the vehicle width direction. Reference numeral 20 denotes a front end of which is pivotally attached to an upper end of a first shackle link 22 by a pin 24 and a rear end of which is a second Is a main leaf spring pivotally connected to a lower end of the shackle link 26 by a pin 28.

The first shackle link 22 has its lower end pivotally attached to a front shackle bracket 32 by a pin 30, and the bracket 32 is fixed to the side rail 12 of the chassis frame 10. The upper end of the second shackle link 26 is pivotally attached to a rear shackle bracket 36 by a pin 34, and the bracket 36 is fixed to the side rail 12 of the chassis frame 10. Therefore, the sprung load of the vehicle body acts on the front end of the main leaf spring 20 via the first shackle link 22 in the suspension direction, while the rear end of the main leaf spring 20 has the second shackle link. Via 26, it acts in such a way that the sprung load is supported. Reference numeral 38 denotes a helper leaf spring that is disposed above the main leaf spring 20 and that has front and rear ends thereof slidably in contact with a helper stopper 40 mounted on the side rail 12 when the load of the vehicle is equal to or greater than a set load. .

A rubber pad member 42, which is well shown in an enlarged side view of FIG. 5, is disposed on the upper side surface and the lower side surface of the rear axle housing 16 near both ends in the vehicle width direction. An upper support member 44 having an inverted U-shaped side surface is mounted on the upper rubber pad member 42, and a lower rubber pad member 42 is mounted on a lower support member 46 having a U-shaped side surface. Have been. A pair of front and rear U-bolts 48 disposed in the front-rear direction intermediate portion of the main leaf spring 20 and the helper leaf spring 38 are inserted through the upper and lower support members 44 and 46 so that a nut 50 is formed.
By tightening the rear axle housing 1
6 are connected to the main leaf spring 20 and the helper leaf spring 3 via rubber pad members 42, respectively.
8 or a leaf spring device for rear wheel suspension.

The rubber pad member 42 has a pair of U-shaped steel back plates 52 and 54 each having a shallow U-shaped cross-section in the vehicle longitudinal direction, and a pair of steel back plates 52 and 54 sandwiched and fixed by baking. And a shallow U-shaped rubber pad 56. A pair of front and rear ear portions 58 project from the back metal 54 of the rubber pad member 42 on the side in contact with the rear axle housing 16, and the ear portions 58 are fixed to the front and rear side surfaces of the rear axle housing 16 by welding or the like. It is fixed to the projection 60 by a bolt 62.

When the U-bolt 48 is tightened as described above, the length of the legs that contact the upper and lower support members 44 and 46 is set to a predetermined length in advance. Is applied with a predetermined compression force. (Note that, in the illustrated embodiment, the leaf spring device for rear wheel suspension includes the main leaf spring 20 and the helper leaf spring 38, but the helper leaf spring 38 may be omitted.)

A lateral rod 64 is disposed above the rear axle housing 16 and extends in the vehicle width direction. One end of the lateral rod 64 is provided with a ball joint device 66 (or a rubber bush joint device having the same effect). A differential casing 68 provided at a substantially central portion in the vehicle width direction of the rear axle housing 16 via
The other end of the lateral rod 64 is pivotally connected to the side rail 12 of the chassis frame 10 via a ball joint device 70 (or an equivalent rubber bush type joint device).

As shown in the side views of FIGS. 2 and 5, a bracket 72 is fixed to an upper portion of the rear axle housing 16 near both ends in the vehicle width direction by welding or the like. Device 7
One end of a pair of left and right lower radius rods 76 is pivotally connected via a joint 4 (or an equivalent rubber bush type joint device). The other end of each lower radius rod 76 has a pair of left and right L-shaped levers 82 whose pivots are pivotally supported by a pivot 80 or a ball joint device, respectively, on a columnar bracket 78 fixed to the web or side wall of the side rail 12.
At the inner end of a lateral arm extending in the vehicle width direction via a ball joint device 84 (or a rubber bush type joint device having the same effect). Further, at the other end of the L-shaped lever 82, that is, at the rear end of a vertical arm extending in the vehicle longitudinal direction, both ends of a connecting rod 86 extending in the vehicle width direction are respectively connected to a ball joint device 88 (or the same effect). (A rubber bush type joint device).

One of the pair of L-shaped levers 82, for example, the left L-shaped lever 82 in the illustrated embodiment,
In a vertical arm extending in the front-rear direction of the vehicle body, a piston shaft 92 of a hydraulic cylinder device 90 forming a rear-wheel steering actuator is provided at an intermediate portion between the pivot 80 and the ball joint device 88 with a ball joint device 94 (or the same effect). Rubber bush type joint device). Further, a cylinder 96 of the hydraulic cylinder device 90 is supported by the bracket 78 on the chassis frame 10 via a ball joint device 98 (or a rubber bush type joint device having the same effect).

The ball joint devices 66, 70, 7
Examples of specific configurations of 4, 84, 88, 94 and 98 are illustrated in FIG. In the figure, reference numeral 100 denotes one member that causes relative rotational displacement, for example, the above-described lateral rod 64,
Lower radius rod 76, bracket 72, connecting rod 86, piston shaft 92 and hydraulic cylinder 96
Reference numeral 102 denotes a ball seat support formed on the other member, for example, the chassis frame 10, the L-shaped lever 82, and the differential case 68. The shaft 106 having the spherical member 104 is supported by the one member 100, and the ball seat 108 slidably contacting the spherical member 104 is supported by the other member 102. With this configuration, one member 100 can freely rotate in the plane perpendicular to the axis of the shaft 106 and in the plane including the coaxial line within the angle ranges set respectively with respect to the other member 102.

FIG. 7 is a conceptual block diagram of a device for controlling the operation of the rear wheel steering actuator 90. Symbol 1 in the figure
Reference numeral 10 denotes a light pulse non-contact type steering angle sensor which is disposed on the steering shaft 112 to detect a steering angle.
14 is a vehicle speed sensor, 116 is a yaw rate sensor, 118
Is the steering angle signal of the steering angle sensor 110 and the vehicle speed sensor 114
Is a controller that receives the vehicle speed signal and the turning signal of the yaw rate sensor 116 to control the control valve 120 that operates the rear wheel steering actuator 90, and 122 is a hydraulic pump.

When the steering wheel 124 is operated and the front wheels 126 are steered while the vehicle is running at high speed, the steering angle signal of the steering angle sensor 110 and the vehicle speed sensor 11
The controller 118 which receives the vehicle speed signal of No. 4 and the turning signal of the yaw rate sensor 116 issues a drive signal to the control valve 120 to operate the control valve. The high-pressure hydraulic oil discharged from the hydraulic pump 122 by the operation of the control valve 120 is supplied to the rear wheel steering actuator 90, and the actuator 90 expands or contracts according to the steering direction of the front wheel 126. When the rear wheels are steered to improve the steering stability during high-speed running of the vehicle, the rear wheels 18 are normally 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 126. .

When the front wheels 126 are steered during high-speed running of the vehicle, the control valve 120 is operated by the command of the controller 118 as described above, and the rear-wheel steering actuator 90 is extended or contracted. For example, when the actuator 90 extends, the left L-shaped lever 8 in FIG.
2 rotates clockwise around the pivot 80, and the left lower radius rod 76 connected to the lever is pulled to the rear of the vehicle body. At the same time, the left L-shaped lever 82
The right L-shaped lever 82 connected via a connecting rod 86 rotates clockwise around the pivot 80, and the lower right radius rod 7 connected to the lever is connected to the right L-shaped lever 82.
6 is driven forward of the vehicle body. As a result, the rear axle housing 16 revolves around the center of the ball joint device 66 at one end of the lateral rod 64, and steering stability during high-speed running is improved in a manner well known in the art.

When turning the rear axle housing 16 for steering, a shallow U-shape in the rubber pad member 42 interposed between the vicinity of both ends in the vehicle width direction of the rear axle housing 16 and the leaf spring devices 20 and 38. Since the rubber pad 56 having a shape is preliminarily given an appropriate pre-compression, the rubber pad 56 flexibly generates a shearing deformation so that the leaf spring device 20 can be used.
And 38, the rear axle housing 16 can rotate relatively smoothly.

According to the structure of the present invention, a V-shaped upper radius rod is used instead of the previously proposed structure.
That a simple rod-shaped lateral rod 64 is used;
Since only one hydraulic cylinder device 90, that is, a rear-wheel steering actuator is used instead of the pair of left and right hydraulic cylinder devices, there is an advantage that the structure is extremely simple and the manufacturing cost and weight can be reduced.

A pair of left and right lower radius rods 76 are connected to a pair of corresponding L-shaped levers 82, and the left and right L-shaped levers 82 are connected to a single connecting rod 86.
, The longitudinal acting force generated at the time of sudden braking, sudden starting, etc. is carried by the connecting rod 86 as a pulling force or a compressive force, and does not substantially act on the rear wheel steering actuator 90. Therefore, the size and weight of the actuator can be reduced.

Furthermore, the left and right lower radius rods 76 are pivotally mounted via brackets 72 to the uppermost part of the rear axle housing 16, as best shown in FIGS. 4 and 5, in particular. By driving and braking torques at the time of sudden braking and sudden starting, etc., are carried on the front and rear shackle links 22 and 26 of the leaf spring device 20, they act on the L-shaped lever 82 and the connecting rod 86 via the lower radius rod 76. Since the force can be reduced, the diameter of these rods can be reduced, and the brackets 72 and 78 can be simplified, there is an advantage that further reduction in weight and manufacturing cost can be achieved.

In this embodiment, the sprung load of the vehicle is such that the front end of the main leaf spring 20
The first shackle link 22 acts in the suspension direction, and the rear end portion is arranged so as to act in the lower support direction via the second shackle link 26. Rear axle housing 16
Is returned to the neutral position, and there is an additional advantage that the steering angle can be easily maintained.

In the above-described embodiment, a vehicle having one rear axle is illustrated. However, in the case of a vehicle having two rear axles, the same rear wheel steering as described above is applied to both the rear front axle and the rear rear axle. An apparatus is provided. In a rear two-axle vehicle, 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 illustrated drive wheels.

[0025]

As described above, the rear wheel steering apparatus such as a truck according to the present invention comprises a chassis frame, a rear axle housing supporting rear wheels at both ends in a vehicle width direction, the rear axle housing and the chassis frame. Left and right leaf spring devices extending in the vehicle front-rear direction, respectively, and are disposed extending in the vehicle width direction, and one end thereof is pivotally attached to the center portion of the rear axle housing in the vehicle width direction. A lateral rod with the other end pivotally attached to the chassis frame,
A pair of left and right lower radius rods which are disposed substantially symmetrically on both sides of the front-rear direction center line of the vehicle body and have one ends pivotally mounted on the rear axle housing, and one end of the lower radius rod pivotally supported on the chassis frame. A pair of left and right L-shaped levers pivotally attached to the other end, connecting rods extending in the vehicle width direction and having both ends pivotally attached to the other ends of the left and right L-shaped levers, respectively; The L-shaped lever is supported by the chassis frame and connected to one of the L-shaped levers, and the other L-shaped lever is rotated through the L-shaped lever and the connecting rod in response to steering and steering of the vehicle during high-speed running. The rear left and right lower radius rods are thereby driven in opposite directions to rotate the rear axle housing around the one end pivot point of the lateral rod. A steering actuator is provided, the above-mentioned leaf spring device is connected to the chassis frame via shackle links capable of swinging the front and rear ends thereof, and the intermediate portion in the front-rear direction is connected to the rear axle housing. The rear axle housing is connected to the rear axle housing via upper and lower rubber pads having a shallow U-shape sandwiched from above and below, so that it is possible to provide a simple, inexpensive and lightweight rear wheel steering device. It is informative.

[Brief description of the drawings]

FIG. 1 is a main part plan view showing a first embodiment of the present invention.

FIG. 2 is a side view of the rear wheel steering device shown in FIG.

FIG. 3 is a cross-sectional view taken along a line III-III in FIG. 2 and viewed in a direction indicated by an arrow.

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2 and viewed in the direction of the arrow.

FIG. 5 is an enlarged side view showing, in an enlarged manner, a connection portion between the leaf spring device and the rear axle housing shown in FIG. 2;

FIG. 6 is a sectional view showing a specific structure of the ball joint device in FIGS. 1 and 2;

FIG. 7 is a schematic configuration diagram of an operation control device of the rear wheel steering actuator in FIG. 1;

[Explanation of symbols]

 Reference Signs List 10 chassis frame 12 side rail 16 rear axle housing 20 main leaf spring (laminated leaf spring device) 22 shear link 26 shear link 42 rubber pad member 64 lateral rod 76 lower radius rod 82 L-shaped lever 86 connecting rod 90 rear wheel steering actuator

Claims (1)

(57) [Claims] 1. A chassis frame, a rear axle housing supporting rear wheels at both ends in a vehicle width direction, and left and right leaf springs interposed between the rear axle housing and the chassis frame and extending in the vehicle longitudinal direction, respectively. A device, a lateral rod extending in the vehicle width direction, one end of which is pivotally connected to a central portion of the rear axle housing in the vehicle width direction and the other end of which is pivotally connected to the chassis frame; A pair of left and right lower radius rods, which are disposed substantially symmetrically on both sides of the center line and have one ends pivotally connected to the rear axle housing, respectively, are pivotally supported on the chassis frame, and each end is pivotally connected to the other end of the lower radius rod. A pair of left and right L-shaped levers attached to each other, extending in the vehicle width direction, and connecting both ends thereof to the other ends of the left and right L-shaped levers. A rod and one of the L-shaped levers supported by the chassis frame and connected to one of the L-shaped levers via the same L-shaped lever and the connecting rod in response to steering and steering of the vehicle during high-speed running; A rear wheel steering actuator for driving the left and right lower radius rods in opposite directions by rotating the rear axle housing about the one end pivot point of the lateral rod. The above-mentioned leaf spring device is connected to the chassis frame via shackle links that can swing at both front and rear ends thereof, and a middle part in the front-rear direction is a shallow U-shape that sandwiches the rear axle housing from above and below. Rear wheels, such as trucks, connected to the rear axle housing via upper and lower rubber pads forming Rudder system.