JPH04118875U - Vehicle rear wheel steering device - Google Patents

Abstract

(57) [Summary] (with amendments) [Purpose] To improve the steering stability of vehicles equipped with a rigid rear axle housing during high-speed driving, to reduce the size and weight of the rear wheel steering actuator, and to further improve the minimum ground clearance. Ensure high. [Structure] The rear end apexes of an upper radius rod 26 and a lower radius rod 34, each having a V-shaped planar shape, are pivotally attached to the upper and lower surfaces of the rear axle housing 16, and the front ends of both legs of the rods are pivoted to the chassis frame 10. wear. Arrange the upper and lower radius rods to form a parallel link mechanism. Rear wheel steering actuators 60 are respectively connected near both ends of the rear axle housing, and when the front wheels are steered during high-speed running, the rear wheel steering actuators are operated in opposite directions to slightly rotate the steering angle.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to a rear wheel steering system for vehicles, particularly trucks.

0002

[Conventional technology]

In order to improve steering stability when the vehicle is running at high speeds, it is linked to the steering of the front wheels. Various four-wheel steering systems and devices have been proposed in which the rear wheels are steered by . However, conventional four-wheel steering systems are not suitable for vehicles where the front and rear wheels are independently suspended. The rear wheel is supported by a rigid axle tube or rear axle housing. Four-wheel steering systems for vehicles such as trucks, especially those with double tires on the rear wheels. No location has been proposed yet.

0003

[Problem that the idea aims to solve]

This invention is based on a truck in which the rear wheels are supported by both ends of the rear axle housing in the vehicle width direction. Improves steering stability during high-speed running on racks, etc., and is small and lightweight. The actuator enables rear wheel steering and ensures sufficient ground clearance. The purpose is to provide a rear wheel steering device that allows be.

0004

[Means to solve the problem]

This invention was devised to achieve the above purpose, and is It supports the rear wheels and is suspended on the chassis frame via a suspension spring device. The rear axle housing is located along the center line in the longitudinal direction of the vehicle body, and its apex is The differential gear installed in the center of the rear axle housing in the width direction of the vehicle. The free ends of both legs are attached to the chassis frame. An upper radius rod with a V-shaped planar shape and an upper radius rod that are pivotally connected to each other. from the pivot point on the top surface of the differential casing to the front of the vehicle. Pivotally attached to the bottom surface of the ferential casing via a rubber bush type joint device. a connecting member, one end of which is rotatable on a horizontal shaft provided on the connecting member, and the other end is rotatable in the axial direction. The planar shape is slidably connected to the chassis frame and the other end is pivoted to the chassis frame. is a bar-shaped lower radius rod, and each output end is mounted on the chassis frame above. The above rear axle housing is installed on both sides of the center line in the longitudinal direction of the vehicle body, and It operates when steering both cars at high speed, and the same rear axle housing is moved above the above. A pair of wheels rotated around a vertical steering axis passing through the pivot center of the horizontal radius rod. A rear wheel steering device for a vehicle, comprising a rear wheel steering actuator. This is what we propose.

[0005]

[Effect]

According to the present invention, the rear axle housing supports the rear wheels at both ends in the vehicle width direction. The top surface of the differential casing is located in the center of the vehicle width direction. and an upper radial whose one end is pivotally connected to the lower surface and which cooperate to form a substantially parallel link mechanism. It is connected to the chassis frame via the ass rod and lower radius rod. , passes through the center of the upper radius rod pivot on the top surface of the differential casing. It can rotate around a longitudinal steering axis. Also the lower radius rod above is from the pivot point of the upper radius rod on the top surface of the differential casing. It is pivotally attached to the lower surface of the casing at the front by a rubber bush type joint device. It is rotatably connected to the horizontal shaft on the connecting member and slidably in the axial direction, so the maximum In addition to being able to avoid a reduction in low ground clearance, the above-mentioned connecting member is a rubber bush type. A cruciform joint that has a joint device and a horizontal axis, and is flexible in the longitudinal direction of the vehicle body. As a result, smooth movement around the steering axis of the rear axle housing is achieved. Rotation is allowed. Preferably approximately symmetrical positions on both sides of the center line in the longitudinal direction of the vehicle body of the rear axle housing. The output ends of a pair of rear wheel steering actuators are connected to the During steering, a pair of actuators operate in opposite directions, causing the rear An axle housing rotates about the longitudinal steering axis. In addition, rear ac The front housing is placed above the differential casing in the center of the vehicle width direction. The upper radius rod and lower radius rod Since it is connected to the arm, the wind-up torque during sudden starts and sudden braking is reduced upwards. and the lower radius rod, and the rear wheel steering actuator has almost no Therefore, the actuator can be made small and lightweight.

[0006]

【Example】

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The code 10 in the figure is A chassis frame of a vehicle such as a rack, which has a pair of left and right sides that extend in the front and back direction of the vehicle body. The rail 12 extends in the width direction of the vehicle and has both ends fixed to the left and right side rails 12. It is composed of a plurality of cross members 14. 16 is both ends in the width direction 20 is a rigid rear axle housing that supports double tires 18, and 20 is the same rear axle housing. Attach fasteners such as U-bolts 22 to the upper side near both ends of the vehicle width direction of the vehicle housing 16. Therefore, the attached spring support member 24 has a hat-shaped side surface. The above-mentioned spring support is disposed at the front and rear of the axle housing 16 across the end thereof. A well-known device interposed between the holding member 20 and the side rail 12 of the chassis frame 10 It is an air spring. 26 is arranged along the center line of the chassis frame 10 in the longitudinal direction of the vehicle body and has a planar shape. is a V-shaped upper radius rod, and the apex of the radius rod is a bow. the flexible joint device 28 or the rubber bushing type flexible joint device (detailed structure thereof). The structure will be explained in detail later. ) through the center part of the rear axle housing 16. It is pivotally mounted on the top surface of the differential casing 30 provided in the The free ends of both legs of the pad are each fitted with a ball joint device 32 or a rubber bush type. It is pivotally connected to the side rail 12 of the chassis frame 10 via a flexible joint device. Ru. The lower part of the upper radius rod 26 has a V-shaped or bar-shaped planar shape (Fig. In the embodiment shown, the former is illustrated) A lower radius rod 34 is disposed, and As clearly shown in FIG. 4, one end of the connecting member 36 extends in the width direction of the vehicle. A metal bushing 40 is attached to the horizontal shaft 38 so that it can rotate freely around the axis and slide in the axial direction. Connected for free movement. The connecting member 36 is a rubber bush type flexible joint device. The ball on the lower surface of the differential casing 30 is connected to the It is attached to the front part of the vehicle body from the joint device 28. In addition, the above downward radial The other end of the ass rod 34 is a ball joint device 44 or a rubber bush type flexible joint. It is pivotally connected to the chassis frame 10 via a joint device. This is well shown in Figure 3. As shown, the differential casing 30 is a funnel-shaped convergence toward the front of the vehicle. shape, the connecting member 36 and the rubber bush type flexible joint device 4 2 is placed directly below the ball joint device 28 of the upper radius rod 26. The reduction in ground clearance can be avoided compared to the upper radius rod. 26 and the lower radius rod 34 constitute a substantially parallel link mechanism in a vertical plane. It is arranged so that

[0007] In particular, as shown well in FIG. 3, the width of the rear axle housing 16 A bracket 46 is provided along with the spring support member 20 on the lower surface near both ends in the direction. They are fastened and fixed together by the U-bolts 22, and the bracket 46 has a ball joint. A pair of left and right actuating rods are connected to each other via a rubber bush type flexible joint device 48 or a rubber bush type flexible joint device. One end of the head 50 is pivotally mounted. The other end of each actuating rod 50 is connected to the side rail. It is pivoted by a pin 54 to a bracket 52 fixed to the web or side wall of the wall 12. The operating levers 56 are pivotally connected to the lower ends of the operating levers 56 by pins 58, respectively. Furthermore, the above At the upper end of the operating lever 56, there is a hydraulic pressure that forms a pair of left and right rear wheel steering actuators. A piston shaft 62 of the cylinder device 60 is pivotally connected by a pin 64, and the piston shaft 62 of the cylinder device 60 is The cylinder 66 of the tuator is connected to the web or the side rail 12 by means of a pin 68. It is pivoted to the side wall.

[0008] An example of the specific configuration of the ball joint devices 28, 32, 44, and 48 is shown in FIG. It is shown. Reference numeral 70 in the figure indicates one of the members that rotates relative to each other, that is, the above-mentioned upper radius slot. rod 26, lower radial slot 34 or actuating rod 50, and 72 represents the other part. materials, namely the differential casing 30 and the mounting bracket of the chassis frame 10. The bracket 46 is shown. The other member 72 includes a spherical member 74. A shaft 76 is supported, and the one member 70 has a bolt that abuts against the spherical member 74. A roll seat 78 is supported. With this configuration, one member 70 is connected to the other member 70. In a plane perpendicular to the axis of the shaft 76 with respect to the member 72 and in a plane including the coaxial line, respectively. It can rotate relatively. FIG. 6 also shows the rubber bush type flexible joint device 42 and the bow. A substantially equivalent joint device used in place of the joint devices 28, 32, 44 and 48. Int device is shown. One member 80 similar to FIG. 5, for example the upper radius The ass rod 26, the connecting member 36, the lower radius rod 34, or the actuating rod 50 82 is the other member, such as the differential casing 30 and the chassis fin. The mounting bracket of the frame 10 or said bracket 46 is shown. One of the above A rubber bush 84 is baked and fixed to the end of the member 80, and the inner periphery of the rubber bush 84 is fixed to the end of the member 80. At the same time, a hollow cylindrical metal bush 86 is fixed by baking. The metal button above A pivot shaft 88 supported by the other member 82 is inserted through the shoe 86 . This structure Due to the configuration, one member 80 is perpendicular to the axis of the pivot 88 relative to the other member 82. can freely rotate within a plane, and one member 80 can be rotated freely in the other member 82. On the other hand, within a plane including the axis of the pivot 88, the rubber bush 84 can be elastically deformed. relative rotation (relative rotation within a small angular range required in this invention). , and furthermore, due to the bending of the rubber bush 84, one part is moved against the pivot 88. The member 80 is allowed to be relatively displaced in the left-right direction in the figure.

[0009] Next, FIG. 7 shows a conceptual diagram of a control device for operating the rear wheel steering actuator 60. FIG. The reference numeral 90 in the figure is inserted into the steering shaft 92 to control the steering angle. For example, a light pulse non-contact type steering angle sensor is used for detection, 94 is a vehicle speed sensor, and 96 is a steering angle sensor. 98 is a steering angle signal from a steering angle sensor 90 and a vehicle speed from a vehicle speed sensor 94. The rear wheel steering actuator 6 receives the signal and the turning signal of the yaw rate sensor 96. 102 is a hydraulic pump. Ru. In this control device, when the vehicle is traveling at high speed, the steering link wheel When the wheel 104 is operated and the front wheels 106 are steered, the steering angle signal from the steering angle sensor 90 is The controller receives the vehicle speed signal from the vehicle speed sensor 94 and the turning signal from the yaw rate sensor 96. The controller 98 issues a drive signal to the control valve 100 to operate the control valve. control The high pressure hydraulic fluid discharged from the hydraulic pump 102 by the operation of the valve 100 is The rudder actuator 60 is supplied to the rudder actuator 60, and the actuator 60 rotates in the left and right opposite directions, i.e. When either the left or right actuator extends, the other actuator contracts. It works like this. A case where the rear wheels are steered to improve steering stability when the vehicle is running at high speeds. When the rear wheels 18 are steered in the same direction as the front wheels 106, the rear wheels 18 are usually steered by a slight angle, for example, 1 to 5 degrees. It is steered to some extent. However, in connection with the steering of the front wheels 106, first the steering of the front wheels 106 The rear wheels 18 are steered by a slight angle in the opposite direction, and after an instant, the rear wheels 18 are turned to the front wheels 10. Adopt other rear wheel steering systems, such as steering at a slight angle in the same direction as No. 6. It is also possible.

0010 In the above configuration, the hydraulic cylinder device 60 forming the rear wheel steering actuator The cylinder 66 has a stroke that limits the extension and retraction strokes of the piston shaft 62. A built-in stopper prevents the rear actuator from operating when the hydraulic cylinder device 60 is activated. The rear housing 16, that is, the rear wheel 18, has a preset slight steering angle of 1 to 5 degrees, for example, 1 degree. The hydraulic cylinder device 60 is provided so that the hydraulic cylinder device 60 can be steered correctly. When stopped, it is locked by the actuation of a built-in neutral spring or hydraulically (the piston (by applying equal hydraulic pressure to both chambers of the piston and fixing the same piston in the neutral position) Therefore, the piston shaft 62 is fixed at the neutral position, and the rear axle housing 16, that is, the piston shaft 62 is fixed at the neutral position. The rear wheels 18 are maintained in a straight-ahead state with zero steering angle. When the front wheels 106 are steered while the vehicle is running at high speed, the controller The control valve 100 is actuated by the command 98, and the pair of rear wheel steering actuators 60 are in opposite directions as shown by the solid and dotted arrows in the schematic diagram of Figure 2. Operate. The actuating lever has one end connected to the piston shaft 62 of each actuator. The bars 56 rotate in opposite directions, and an actuator connected to the other end of one actuating lever 56 The actuating rod 50 that becomes the output end of the tuator is pulled toward the front of the vehicle, and the other actuating lever The operating rod 50 connected to the other end of the -56 is driven toward the rear of the vehicle body. As a result, The rear axle housing 16 is located at the top of the V-shaped upper radius rod 26. The vertical steering axis O-O passing through the center of the provided ball joint device 28 (Fig. (Refer to 3) The steering is performed by rotating the set steering angle, for example, by one degree in either direction to the left or right. As a result, handling stability at high speeds is improved in a manner well known in the art. At this time, the lower radius rod 34 is placed on the lower surface of the differential casing 30. The horizontal axis of the connecting member 36 pivotally supported via the rubber bush type flexible joint device 42 38, the center of the joint device 42 is aligned with the steering axis O. Although the rubber bush 84 is located at a distance from the -O toward the front of the vehicle, Due to elastic deformation, the rear axle housing 16 can be smoothly steered by a small angle. be called. The rotation of the rear axle housing 16 around the steering axis O-O is not shown in the figure. In the case of the embodiment, since the suspension spring is the air spring 24, The rubber diaphragm 108 (see Fig. 3) bends freely in the horizontal direction. The process is extremely smooth. Also, a suspension can be used instead of the air spring 24 mentioned above. When a leaf spring is used as a spring ring, the leaf spring and leaf spring are A rubber pad or the like is interposed between the leaf spring and the axle housing 16. The rear axle housing 16 moves horizontally within the range of the above set steering angle. What is necessary is just to configure it so that it can be relatively displaced. In addition, it is possible to prevent damage to the undercarriage frame 10 that occurs while the vehicle is traveling straight or while turning during steering. The vertical movement of the rear axle housing 16 is caused by the air spring 24 receiving the load. At this time, the rear axle housing 16 is placed in the upper radius slot. Parallel link movement is performed up and down by the rod 26 and the lower radius rod 34. Furthermore , the upper radius rod 26 and the lower radius rod 34 are each a ball joint. The rear Differential casing 30 and chassis frame 10 of the axle housing Since the rear axle housing is pivotally connected to the The left and right tilting of the tag 16 is not hindered. Furthermore, the rear axle housing 16 is connected to the upper radius rod 26 and the lower radius rod 26. Since it is connected to the chassis frame 10 by the radius rod 34, sudden starts and The windup torque that occurs during braking and sudden braking is applied to the upper radius rod 26 and the lower radius rod 26. It is largely carried by the radius rod 34. Therefore, the rear wheel steering actuator The motor 60 is a small and lightweight hydraulic cylinder with virtually no wind-up torque acting on it. device can be safely employed. Further, the lower radius rod 34 is The link installed on the bottom surface of the differential casing in front of the steering axis O-O. Since it is pivotally connected to the coupling member 36, it is possible to It is possible to avoid a reduction in low ground clearance and prevent deterioration of rough terrain driving performance. stomach. In addition, in the above embodiment, a vehicle with one rear axle is illustrated, but a vehicle with two rear axles is used. In both cases, the same rear wheel steering device as above is provided on both the rear front axle and the rear rear axle. Ru. In addition, in vehicles with two rear axles, one of the rear axles is often a dead axle that does not transmit driving force. However, the steering device itself is substantially the same as the drive wheel case described above. It is.

[0011]

[Effect of the idea]

As described above, the vehicle rear wheel steering device according to the present invention has rear wheels at both ends in the vehicle width direction. The rear suspension is supported by the chassis frame via a suspension spring device. The axle housing is arranged along the center line in the longitudinal direction of the vehicle body, with its apex above Differential lock installed in the center of the rear axle housing in the width direction The free ends of both legs are pivoted to the upper surface of the chassis frame, respectively. The upper radius rod has a V-shaped planar shape, and the upper radius rod from the pivot point on the top surface of the differential casing to the front of the vehicle. The connection is pivotally connected to the lower surface of the Rental casing via a rubber bush type joint device. a connecting member, and one end of which is rotatably slidable in the axial direction on a horizontal shaft provided on the connecting member. The planar shape is a V-shape or a rod, which is movably connected and whose other end is pivotally connected to the chassis frame. A lower radius rod with a shape of It is installed on both sides of the center line of the rear axle housing in the longitudinal direction of the vehicle. It operates when steering while driving at high speed, and moves the rear axle housing to the above-mentioned upper rack. A pair of rear wheels that rotate around a vertical steering axis that passes through the pivot center of the Zias rod. The steering actuator is characterized by a rigid rear axle tube, i.e., a rear steering actuator. Improves steering stability during high-speed driving of trucks etc. equipped with axle housings. In addition to achieving a smaller and lighter rear wheel steering actuator, , it is possible to avoid a reduction in the minimum ground clearance, which is useful in practice.

[Brief explanation of drawings]

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

FIG. 2 is a schematic plan view of the rear wheel steering device shown in FIG. 1.

FIG. 3 is a side view of the rear wheel steering device shown in FIG. 1.

4 is a sectional view of a connecting portion between a lower radius rod and a differential casing in FIG. 1. FIG.

5 is a sectional view showing an example of a ball joint device in the rear wheel steering device shown in FIG. 1. FIG.

6 is a sectional view showing another example of the rubber bush type flexible joint device in the rear wheel steering device shown in FIG. 1. FIG.

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

[Explanation of symbols]

10 Chassis frame 16 Rear axle housing 18 Rear wheel 26 Upper radius rod 34 Lower radius rod 60 Rear wheel steering actuator

Claims (1)

[Scope of utility model registration request] 1. A rear axle housing that supports a rear wheel at both ends in the vehicle width direction and is suspended from a chassis frame via a suspension spring device, and a rear axle housing that is disposed along a longitudinal center line of the vehicle body and whose apex is connected to the rear axle housing. an upper radius rod having a V-shaped planar shape, which is pivotally connected to the upper surface of the differential casing provided in the center portion of the housing in the vehicle width direction, and whose free ends of both legs are respectively pivotally connected to the chassis frame; a connecting member pivotally connected to the bottom surface of the differential casing at the front of the vehicle from the pivot point on the top surface of the differential casing of the radius rod via a rubber bush type joint device;
A lower radius rod having one end rotatably connected to the horizontal axis provided on the connecting member and slidably in the axial direction, and the other end pivotally connected to the chassis frame and having a V-shaped or rod-shaped planar shape. are mounted on the chassis frame, and have their output ends mounted on both sides of the center line in the longitudinal direction of the vehicle body of the rear axle housing, and are activated when the vehicle is steered at high speed to connect the rear axle housing to the pivot point of the upper radius rod. A rear wheel steering device for a vehicle, comprising: a pair of rear wheel steering actuators that rotate around a longitudinal steering axis passing through the center of arrival.