JPH0564057U - Rear wheel steering system such as truck - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To provide a rear wheel steering device having a simple structure, small size and light weight, and excellent durability in a truck or the like. [Structure] A chassis frame 10, a rear axle housing 16 supporting rear wheels at both ends in the vehicle width direction, a leaf spring device 20 interposed therebetween, and an apex portion of the rear axle housing 16 pivoted to a central portion in the vehicle width direction. The upper radius rod 60, which has both free ends of which are pivotally attached to the chassis frame 10, and a pair of left and right lower radius rods 72 arranged substantially symmetrically on both sides of the longitudinal centerline of the vehicle body.
It is provided with a pair of rear wheel steering actuators 82 that are activated when the vehicle is steered to rotate the rear axle housing 16. The leaf spring device 20 has both front and rear ends thereof connected to the chassis frame 10 via shackle links 22 and 26 capable of swinging, respectively, and an intermediate portion in the front-rear direction thereof has a shallow U-shaped upper and lower portions. The rear axle housing 16 is connected via a rubber pad 42.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a rear wheel steering device for a truck or the like.

[0002]

[Prior Art]

 Recently, 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 traveling. However, steering of the rear wheels such as a truck in which the rear wheels are supported by the rigid axle tube or both ends of the rear axle housing in the vehicle width direction and the rear axle housing is suspended on the chassis frame via the leaf spring device is not possible. As described above, the rear axle housing itself, whose both ends in the vehicle width direction are connected to the chassis frame via the leaf spring device, is rotated around the center of rotation on the longitudinal center line of the vehicle body during steering. However, various technically difficult problems occur. Conventionally, in order to enable the rear axle housing to rotate around the center of rotation when steering the rear wheels, it is frictionally slid with respect to a leaf spring support bracket that supports the stack leaf spring device with respect to the chassis frame. The structure to allow it has already been proposed. However, with this proposed structure, the entire large and heavy leaf spring assembly must be frictionally slid forward and backward when the rear axle housing is turned, so the leaf spring support bracket on the chassis frame side. There is a problem that the sliding surface is significantly worn, the hydraulic cylinder device for steering becomes large, and the related devices such as the hydraulic control valve and the hydraulic power source become large in size, and the cost becomes high.

[0003]

[Problems to be solved by the device]

 The present invention is a rear wheel steering device having a simple structure, low cost, and excellent durability, which can improve the steering stability at high speed traveling in a truck or the like in which the rear wheels are supported at both ends of the rear axle housing in the vehicle width direction. It is intended to provide.

[0004]

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 a space between the rear axle housing and the chassis frame. The leaf spring device is installed along the longitudinal center line of the vehicle body and one end of the leaf spring device is pivotally attached to the central portion of the rear axle housing in the vehicle width direction and the other end is attached to the chassis frame. The upper radius rods pivotally attached to each other, the pair of left and right lower radius rods pivotally attached to the rear axle housing, and the other ends of the lower radius rods pivotally attached to the rear axle housing at one end of each of the upper and lower radius rods arranged substantially symmetrically with respect to each other. And the left and right lower radius rods are driven in the front-rear opposite direction by operating when the vehicle is steered to move the rear axle housing to the upper radius. One end of the saddle is provided with a pair of rear wheel steering actuators that rotate around a pivot point, and the above-mentioned weight leaf spring device is mounted on the chassis via shackle links that can swing both front and rear ends thereof. A truck or the like characterized in that it is connected to the frame, and an intermediate portion in the front-rear direction is connected to the rear axle housing via upper and lower shallow U-shaped rubber pads that sandwich the rear axle housing from above and below. It proposes a rear wheel steering device.

[0005]

【Example】

 Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. Reference numeral 10 in the drawing denotes a chassis frame of a vehicle such as a truck, and a pair of left and right side rails 12 extending in the front-rear direction of the vehicle body, and both side rails 12 extending in the vehicle width direction fixed to the left and right side rails 12 described above. And a plurality of cross members 14. 16 is a rear axle housing supporting double tires 18 at both ends in the vehicle width direction, and 20 is 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 shackle link. It is a main leaf spring (lap spring device) pivotally attached to the lower end of 26 by a pin 28.

As best shown in the enlarged cross-sectional view of FIG. 3, the lower end of the first shackle link 22 is pivotally attached to a front shackle bracket 32 by a pin 30, and the bracket 32 is attached to the chassis frame 10. It is fixed to the side rail 12. The second shackle link 26 is pivotally attached to the rear shackle bracket 36 by a pin 34 at the upper end thereof, as shown in the enlarged cross-sectional view of FIG. 4, and the bracket 36 is attached to the chassis frame 10. It is fixed to the side rail 12 of. Therefore, the sprung load of the vehicle body acts on the front end of the main leaf spring 20 through the first shackle link 22 in the hanging direction, while the rear end of the main leaf spring 20 has the second end. Through the shackle link 26, the sprung load acts in such a manner that it is supported under the load. Reference numeral 38 denotes a helper leaf spring which is disposed above the main leaf spring 20 and whose front and rear end portions are slidably contacted with the helper topper 40 mounted on the side rail 12 when the load of the vehicle is equal to or more than a set load. ..

Rubber pad members 42 shown in an enlarged perspective view of FIG. 5 are arranged 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 is mounted on the upper rubber pad member 42, and a lower rubber pad member 42 is mounted on the lower support member 46. A spacer 48 is interposed between the upper support member 44 and the lower support member 46, and a pair of front and rear U bolts 50 arranged in the front-rear intermediate portion of the main leaf spring 20 and the helper leaf spring 38 By inserting the upper and lower support members 44 and 46 and the pipe-shaped spacer 48 and tightening the nut 52, both end portions of the rear axle housing 16 are respectively inserted through the rubber pad members 42 and the main leaf spring 20 and the helper. It is connected to the leaf spring 38.

The rubber pad member 42 has a pair of steel plate backings 54 and 56 each having a shallow U-shaped cross section, and a shallow U-shape that is interposed between the backings 54 and 56 and baked and fixed. It is composed of a rubber pad 58. Since the spacer 48 having a predetermined length is interposed between the upper and lower support members 44 and 46 when the U bolt 50 is tightened as described above, the rubber pad 58 has a predetermined compression force. Is working. (In the illustrated embodiment, the leaf spring device for suspension of the rear wheels is composed of the main leaf spring 20 and the helper leaf spring 38, but the helper leaf spring 38 may be omitted.)

Between the side rails 12 of the chassis frame 10, an upper radius rod 60 having a V-shaped planar shape is arranged along the centerline in the vehicle front-rear direction, and the apex portion of the radius rod has a ball joint device 62. (Or a rubber bush type joint device of the same effect), the upper end of a differential casing 64 provided in the central portion of the rear axle housing 16 is pivotally attached, and the free ends of both legs of the rod are respectively ball-shaped. It is pivotally attached to the side rail 12 (or the cross member 14) of the chassis frame 10 via a joint device 66 (or a rubber bush type joint device having the same effect).

As shown in the side view of FIG. 2, brackets 68 are fixed to the lower side surfaces of the rear axle housing 16 near both ends in the vehicle width direction by welding or the like, and a ball joint device 70 is attached to the bracket 68. One end of a pair of left and right lower radius rods 72 is pivotally attached via (or a rubber bush type joint device having the same effect). The other end of each lower radius rod 72 is pivotally attached via a pin 80 to the lower end of an operating lever 78 pivotally supported by a pin 76 on a bracket 74 fixed to the web or side wall of the side rail 12. Further, a piston shaft 84 of a hydraulic cylinder device 82 forming a pair of left and right rear wheel steering actuators is pivotally attached to the upper end of the operating lever 78 by a pin 86, and a cylinder 88 of the hydraulic cylinder device is attached by a pin 90 to the above. It is pivotally supported on the web or side wall of the side rail 12.

An example of a specific configuration of the ball joint devices 62, 66 and 70 is shown in FIG. Reference numeral 92 in the drawing denotes one member that causes relative rotational displacement, that is, the upper radius rod 60 or the lower radius rod 72, and 94 denotes the other member, that is, the rear axle housing 16 or the bracket 68. The other member 94 supports a shaft 98 having a spherical member 96, and the one member 92 supports a ball seat 100 that abuts the spherical member 96. With this configuration, one member 92 can freely rotate with respect to the other member 94 in a plane orthogonal to the axis of the shaft 98 and in a plane including a coaxial line.

Finally, FIG. 8 is a conceptual configuration diagram of an apparatus for controlling the operation of the rear wheel steering actuator 82. In the figure, reference numeral 102 is, for example, a light pulse non-contact type steering angle sensor mounted on a steering shaft 104 to detect a steering angle, 106 is a vehicle speed sensor, 108 is a yaw rate sensor, and 110 is a steering angle signal of the steering angle sensor 102. The controller 114 receives the vehicle speed signal of the vehicle speed sensor 106 and the turning signal of the yaw rate sensor 108 to control the control valve 112 that operates the rear wheel steering actuator 82, and 114 is a hydraulic pump. When the steering wheel 116 is operated and the front wheels 118 are steered while the vehicle is traveling at high speed, the steering angle signal of the steering angle sensor 102, the vehicle speed signal of the vehicle speed sensor 106, and the turning signal of the yaw rate sensor 108 are received. The controller 110 sends a drive signal to the control valve 112, which operates the control valve. The high-pressure hydraulic oil discharged from the hydraulic pump 114 is supplied to the pair of rear wheel steering actuators 82 by the operation of the control valve 112, and when the actuators 82 extend in the left and right directions, that is, when one of the left and right actuators extends, the other The actuator operates so as to contract.

When the rear wheels are steered for the purpose of improving steering stability when the vehicle is traveling at high speed, the rear wheels 18 usually have a small steering angle, for example, 1 to 5 degrees in the same direction as the front wheels 118. Steered to a degree. However, in relation to the steering of the front wheels 118, the rear wheels 18 are first steered by a slight angle in the opposite direction to the steering direction of the front wheels 118, and after a moment, the rear wheels 18 are slightly moved in the same direction as the steering directions of the front wheels 118. It is also possible to adopt other rear-wheel steering systems such as angle steering.

When the front wheels 118 are steered while the vehicle is traveling at high speed, the control valve 112 operates according to the command from the controller 110 as described above, and the pair of rear wheel steering actuators 82 operate in mutually opposite directions. .. The actuating levers 78, one end of which is connected to the piston shaft 84 of each actuator, rotate in opposite directions, and the lower radius rod 72 that is connected to the other end of one of the actuating levers 78 is pulled toward the front of the vehicle body, The lower radius rod 72 connected to the other end of the operating lever 78 is driven rearward of the vehicle body. As a result, as shown in the schematic plan view of FIG. 7, the rear axle housing 16 is rotated around the apex of the V-shaped upper radius rod 60 at a set steering angle, for example, 1 ° in either the left or right direction. Since the vehicle is moved and steered, the steering stability during high speed traveling is improved in a manner well known in the art. When the rear axle housing 16 is rotated for steering, it forms a shallow U-shape inside 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 58 is given a proper pre-compression in advance, the rubber pad 58 causes a flexible shear deformation so that the rear axle housing 16 can smoothly rotate relative to the leaf spring devices 20 and 38. You can Therefore, the capacity of the hydraulic cylinder device 82 and the capacities of the related valve device and pressure oil source are larger than those of the conventional device in which the leaf spring device as a whole is frictionally slid in the front-rear direction of the vehicle body when steering the rear wheels. Can be made smaller, and the entire hydraulic system can be made smaller, lighter, and cheaper. Further, the leaf spring devices 20 and 38 for suspension of the rear axle, the shackle links 22 and 26, the shackle brackets 32 and 36, and the like can be mostly shared with those for a normal vehicle of the same type that does not perform rear wheel steering. Therefore, also from this point, there is an advantage that the manufacturing cost can be reduced. Further, there is no member that causes significant wear like the leaf spring support member in the above-described conventional structure in which the front and rear ends of the leaf spring device are frictionally slid against the chassis frame to support the rear axle housing. The rubber pad 58 that clamps the upper and lower sides has a shallow U-shape, and when the rear wheel is steered, the front and rear legs cause compressive deformation and cooperate with the upper and lower flat parts, so that the rubber pad is excessively deformed. Since it does not exist, it has the advantage of excellent durability.

Further, the vertical movement of the rear axle housing 16 with respect to the chassis frame 10 during the straight traveling of the vehicle and the turning traveling during steering is, of course, performed such that the leaf spring devices 20 and 38 receive the load. The housing 16 performs a parallel link movement up and down by the upper radius rod 60 and the lower radius rod 72. Further, the upper radius rod 60 is pivotally attached to the rear axle housing 16 and the chassis frame 10 by ball joint devices 62 and 66 (or a rubber bush type joint device of the same effect), and the lower radius rod 72 is similar to the ball joint device 70 ( Or a rubber bush type joint device having the same effect), the rear axle housing 16 is pivotally attached to the rear axle housing 16. Therefore, even if the rear axle housing 16 tilts left or right or rolls when traveling on a bumpy road or turning, the displacement of Is not hindered.

Further, in the case of this embodiment, as shown in FIGS. 3 and 4, the sprung load of the vehicle is suspended at the front end of the main leaf spring 20 via the first shackle link 22. Since the rear end portion is arranged so as to act in the lower supporting direction via the second shackle link 26, the sprung load returns the rear axle housing 16 to the neutral position during the steering operation. This has the additional advantage of making it easier to maintain the steering angle.

In the above embodiment, a vehicle having a single rear axle is illustrated, but in the case of a vehicle having two rear axles, the same rear wheels as those described above are used for both the rear front axle and the rear rear axle. A steering device is provided. Further, in a rear two-axle vehicle, one of the rear axles is often constructed as a dead axle that does not transmit driving force, but the steering device itself is substantially equivalent to the case of the exemplified drive wheels.

[0018]

[Effect of the device]

 As described above, the rear wheel steering system according to the present invention comprises a chassis frame, a rear axle housing supporting rear wheels at both ends in the vehicle width direction, and an interposition between the rear axle housing and the chassis frame. The stacked leaf spring device is arranged along the longitudinal center line of the vehicle body, and one end thereof is pivotally attached to the central portion in the vehicle width direction of the rear axle housing and the other end is pivotally attached to the chassis frame. Upper radius rod, a pair of left and right lower radius rods which are arranged substantially symmetrically on both sides of the longitudinal center line of the vehicle body and have one end pivotally attached to the rear axle housing, and the other end of the lower radius rod. When the vehicle is steered, the lower left and right radial rods are driven in the opposite directions to move the rear axle housing to the upper radial rods. A pair of rear wheel steering actuators that rotate around a pivot point are provided, and the leaf spring device is connected to the chassis frame through shackle links that are swingable at both front and rear ends thereof. A truck having a rigid rear axle housing, characterized in that its front-rear intermediate portion is connected to the rear axle housing via upper and lower shallow U-shaped rubber pads that sandwich the rear axle housing from above and below. A structure that can improve steering stability during high-speed driving such as a simple structure, small size and light weight, low manufacturing cost, and excellent durability can be provided, which is practically useful.

[Brief description of drawings]

FIG. 1 is a plan view of an essential part showing an embodiment of the present invention.

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

3 is a cross-sectional view of a mounting portion of a front end portion of the main leaf spring shown in FIG. 2 to a chassis frame.

FIG. 4 is a cross-sectional view of a mounting portion of the rear end portion of the main leaf spring to the chassis frame.

FIG. 5 is an enlarged perspective view of a rubber pad member interposed in a connecting portion between the main leaf spring and the rear axle housing.

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

FIG. 7 is a schematic plan view showing the behavior of the rear axle housing when steering the rear wheels.

8 is a schematic configuration diagram of an operation control device for a rear wheel steering actuator in FIG.

[Explanation of symbols]

 10 Undercarriage Frame 12 Side Rail 16 Rear Axle Housing 20 Main Leaf Spring (Layered Spring Device) 22 First Shackle Link 26 Second Shackle Link 42 Rubber Pad Member 60 Upper Radius Rod 72 Lower Radius Rod 82 Rear Wheel Steering Actuator

Claims (1)

[Scope of utility model registration request] 1. A chassis frame, a rear axle housing which supports rear wheels at both ends in the vehicle width direction, a leaf spring device interposed between the rear axle housing and the chassis frame, and a longitudinal centerline of the vehicle body. Upper radius rods, one end of which is pivotally attached to the central portion of the rear axle housing in the vehicle width direction and the other end of which is pivotally attached to the chassis frame, respectively, and which are substantially symmetrical on both sides of the longitudinal centerline of the vehicle body. And a pair of left and right lower radius rods pivotally attached to the rear axle housing and the other ends of the lower radius rods, respectively,
The vehicle includes a pair of rear wheel steering actuators that are activated when the vehicle is steered to drive the left and right lower radius rods in opposite front and rear directions to rotate the rear axle housing around one end pivot point of the upper radius rod. The leaf spring device is connected to the chassis frame via shackle links that can swing both front and rear ends thereof,
A rear wheel steering device for a truck or the like, wherein an intermediate portion in the front-rear direction is connected to the rear axle housing via upper and lower shallow U-shaped rubber pads that sandwich the rear axle housing from above and below.