JPH0525353Y2 - - Google Patents

Description

[Detailed description of the invention] 〓Field of industrial application〓 The present invention relates to a rear axle steering system for an automobile, and particularly relates to a rear axle steering system for a vehicle in which the rear axle is suspended by a suspension spring consisting of a leaf spring. .

〓Summary of the invention〓 This invention supports one end of a leaf spring that suspends the rear axle so that it can slide in the front and rear direction, and
One end of the leaf spring is connected to the vehicle body via an actuator, and the actuator rotates the rear axle via the leaf spring to perform steering.

〓Conventional technology〓 Trucks have been widely used in the past to transport various types of cargo. As suspension devices for rear axles that are subject to particularly large loads, suspension devices made of leaf springs are widely used. Such a suspension device has a simple structure, can withstand a large load, and is highly durable.

〓Problems to be solved by the invention〓 However, in conventional trucks with leaf suspensions, the rear axle is fixed to the suspension spring, and the leaf spring is attached to a predetermined position on the frame. I was getting used to it. Therefore, such a rear axle cannot turn, and the wheels attached to this axle cannot be steered. A structure that allows the rear wheels to turn around a kingpin in the same way as the front wheels in order to improve steering and maneuverability is heavy and expensive. In addition, in the case of a double tire such as a truck, it is difficult to adopt it due to space considerations.

The present invention was developed in view of these problems, and is a rear axle steering system that uses a simple structure to enable rear wheel steering, improves steering stability, and increases maneuverability. The purpose is to provide a device.

〓Means for solving the problem〓 The present invention provides a vehicle in which the rear axle is suspended by a suspension spring consisting of a leaf spring, in which the intersecting angle of the rear axle with respect to the leaf spring can be changed. The rear shaft is attached to the leaf spring via a permitting member that allows rotation in the yaw direction, supports the leaf spring so as to be movable in the front-rear direction, and connects one end of the leaf spring via an actuator. A rear axle steering system for an automobile, characterized in that the rear axle is connected to a vehicle body, and left and right actuators move left and right leaf springs in opposite directions, thereby turning the rear axle to perform steering. It is related to the device.

〓Operation〓 When the left and right leaf springs are moved in opposite directions by the left and right actuators, the intersecting angle of the rear shaft attached to the left and right leaf springs through the respective allowable members changes with respect to the leaf springs. It is rotated in the yaw direction, thereby steering the rear axle.

〓Example〓 The present invention will be described below with reference to an illustrated example.
2 and 3 show a truck equipped with a rear axle steering device according to an embodiment of the present invention, and this truck is equipped with a pair of left and right frames 10 constituting its framework. A cab 11 is supported on the front end side. The front end side of the frame 10 is supported by a front shaft 12, and the rear side is supported by a rear shaft 13. Note that the rear shaft 13 is composed of a drive shaft and is driven by an engine.

Next, the structure of the suspension of the rear axle 13 consisting of this drive shaft will be explained. As shown in FIGS. 4 and 5, the rear axle 13 is suspended by a suspension spring consisting of a leaf spring 20. It's getting old. leaf spring 20
is supported at its front end by a center pin 22 of a front bracket 21 attached to the frame 10. On the other hand, leaf spring 20
The rear end portion of is supported by a shackle 23.
A shackle 23 is rotatably supported by a rear bracket 24.

A front bracket 21 having an eye pin 22 that is engaged with the front end of the leaf spring 20.
is frame 1, as shown in FIGS. 5 and 6.
It is supported so as to be slidable in the front and rear directions by a slide guide 25 that is fixedly attached to the slide guide 25 . This allows the spring 20 to be supported so as to be movable in the front and back direction. A square tubular rubber bush 27 is interposed between the leaf spring 20 and the axle 13, and the axle 13 is connected to the axle 13 by a connecting bolt 28 via the rubber bush 27.
is coupled to the leaf spring 20. Note that the rubber bush 27 makes it possible to change the intersection angle of the rear shaft 13 with respect to the leaf spring 20.
It allows rotation in the yaw direction, and constitutes the permitting member of the present invention. Furthermore, the axle 13 is connected to the frame 10 by a pair of torque rods 26. As shown in FIG. 4, these torque rods 26 are connected to approximately the center of the axle 13, are arranged in a V-shape, and are connected to the frame 10 at their front ends.

It is also possible to adopt the structure shown in FIG. 7 instead of the structure shown in FIG. 6 as a structure for slidably supporting the front bracket 21 with respect to the frame 10 in the longitudinal direction. That is, only the lower end of the front bracket 21 is supported by the slide guide 25, the rollers 30 are arranged so as to contact the upper surface of the front bracket 21, and the rollers 30 are supported on the frame 10 by the brackets 29. You may also do so. According to such a structure, the front bracket 21 can be moved more easily, and the energy required for turning can be reduced.

In addition, the rubber bush 27 disposed between the axle 13 and the leaf spring 20 has a cylindrical structure as shown in FIGS. 8 and 9 instead of a square cylinder as shown in FIG. You may also use something. This rubber bushing 27 includes an inner ring 31 and an outer ring 32, and further has recesses 33 formed at the front and rear.
By using such a rubber bush 27, the rotational movement of the axle 13 relative to the leaf spring 20, that is, the movement of the axle 13 in the yaw direction is facilitated. In other words, for example, if the leaf spring 20 on the left side of the vehicle is moved forward and the leaf spring 20 on the right side is moved backward, the axle 13 will rotate around the center of the vehicle, but the leaf spring 20 will move in the front and rear direction. The axle 13 changes from a perpendicular state to an inclined state, and its movement becomes easier.

Next, a structure for moving the front bracket 21 connected to the front end of the leaf spring 20 will be explained. As shown in FIG. 1, the front bracket 21 is connected to a piston rod 35. The piston rod 35 is further connected to a piston 36, which is disposed within a hydraulic cylinder 37.
The hydraulic cylinder 37 is adapted to be connected to the frame 10. The hydraulic cylinder 37 is connected to a switching valve 38, and further connected to an oil pump 39 and a reservoir 40 via the switching valve 38.

The actuator 46 for switching the spool of the switching valve 38 is operated by a microcomputer 47.
It has come to be controlled by The input side of this microcomputer 47 includes a steering angle sensor 49 that detects the steering angle of the steering wheel 48, a vehicle speed sensor 50, and a yaw rate sensor 5.
1 and a lateral acceleration sensor 52, respectively.

Next, to explain the steering operation of this rear axle steering system configured as described above, the switching valve 38 is controlled via the actuator 46 by a control signal from the microcomputer 47 shown in FIG.
By moving the spool, oil pressurized by the oil pump 39 can be supplied to the front or rear chamber of the piston 36 of the hydraulic cylinder 37, thereby making it possible to move the piston 36. It becomes possible.

Then, by pushing out the piston rod 35 of one of the left and right hydraulic cylinders 37, for example, the left hydraulic cylinder 37, and retracting the piston rod 35 of the right hydraulic cylinder 37, these hydraulic cylinders 37 are moved to the leaf spring 20. are moved in the front-back direction, respectively, and it becomes possible to turn the rear shaft 13 to the left via the pair of left and right leaf springs 20. As a result, the rear axle 13 is steered. At this time, the rear shaft 13 rotates in the yaw direction by a small angle with respect to the leaf spring 20, but this rotation in the yaw direction is permitted by the rubber bush 27. Further, lateral displacement of the rear shaft 13 is prevented by a pair of torque rods 26 arranged in a V-shape on the upper side.

This rear shaft 13 is controlled by a microcomputer 47.
To explain the control for steering in more detail, as shown in the flowchart shown in FIG. 10, the microcomputer 47 reads the steering angle of the steering wheel 48 using the sensor 49. Next, the vehicle speed is read by the vehicle speed sensor 50, and the steering angle of the rear axle 13 is calculated based on these values. Further, based on the stroke of the piston rod 35 of the hydraulic cylinder 37, the steering angle of the rear shaft 13 is read by the stroke sensor 53. This actual steering angle is then compared with the calculated value. If the calculated value is larger, the rear shaft 13 is further turned and steered. On the other hand, if the calculated value is smaller, the rear shaft 13 is rotated in the returning direction.

Furthermore, in this rear axle steering system, the rear axle 13 is steered in response to changes in vehicle speed and load, thereby improving and maintaining stable steering performance. This operation is performed based on the flowchart shown in FIG. The microcomputer 47 reads the steering angle of the steering wheel 48 and calculates a standard yaw rate according to this steering angle. Furthermore, the microcomputer 47 reads the yaw rate, that is, the angular velocity of yawing, using the yaw rate sensor 51. Then, this actual yaw rate is compared with the standard yaw rate, and if the actual yaw rate is outside the range of the standard yaw rate, the rear axle 13 is moved to the leaf spring 20.
The steering correction is performed by turning the steering wheel by means of a hydraulic cylinder 37 connected to the steering wheel.

Note that instead of steering correction using yaw rate, the first
It is also possible to perform steering correction based on the detection of lateral acceleration as shown in the flowchart shown in FIG. In this case, the steering angle of the steering wheel 48 is read by the steering angle sensor 49, and the standard lateral acceleration at this steering angle is calculated. Then, the actual lateral acceleration obtained by the lateral acceleration sensor 52 is read, and the calculated value is compared with the actual lateral acceleration. If the actual lateral acceleration value is outside the range of the standard lateral acceleration, the front bracket 21 is moved by the hydraulic cylinder 37 connected to the leaf spring 20, and the steering is corrected by turning the rear shaft 13. .

Generally, the yaw rate or lateral acceleration of a vehicle changes depending on the vehicle speed. In addition, the steering stability changes depending on the position of the cargo, and furthermore, the vehicle receives lateral forces due to external disturbances such as crosswinds and road slopes, which changes the steering stability. It turns out. However, such a change in maneuverability occurs when the rear axle 1
3 by the device shown in FIG. 1, it is possible to maintain a certain level of steering stability. Therefore, such a vehicle can improve maneuverability, especially at medium and high speeds.
Furthermore, by steering the rear axle 13 in this manner, the minimum turning radius can be reduced, and the difference between the inner and outer wheels can be reduced. It becomes possible to reduce wear.

Furthermore, according to the rear axle steering device according to this embodiment,
The rear axle 13 to which the rear wheels are attached is rotated as a whole, and has a different structure from the front wheel steering mechanism, in which the rear wheels are rotatably supported by a kingpin for steering. . That is, a rubber bush 27 is interposed between the rear shaft 13 and the leaf spring 20, and a front bracket 21 that supports the front end of the leaf spring 20 is provided.
By moving the rear shaft 13 in the front-rear direction,
The whole can be rotated. Therefore, it is possible to steer the rear axle 13 with a very simple structure, the number of parts is small, the weight hardly increases, and the rear axle steering is very advantageous in terms of cost. It becomes possible to provide the device.

Next, a second embodiment of the present invention will be described with reference to FIG. Note that in this second embodiment, the first
Parts corresponding to those in the first embodiment shown in the figures are given the same reference numerals, and descriptions of parts having the same configuration will be omitted. The feature of this second embodiment is that a geared motor 60 and a feed screw 6 are used as means for moving the front bracket 21 that supports the front end of the leaf spring 20 in the front and back direction.
1 is used. The output shaft of a geared motor 60 attached to a frame constituting the vehicle body is configured as a feed screw 61, and is adapted to engage with a female screw hole 63 of a bracket 62 connected to the front bracket 21. The geared motor 60 is connected to the microcomputer 4.
It is designed to be driven by a drive circuit 64 controlled by 7. In this embodiment as well, the left and right geared motors 60 are connected to the drive circuit 64 so as to rotate in opposite directions.

Therefore, by driving the left and right geared motors 60 via the drive circuit 64 based on instructions from the microcomputer 47, for example, the right bracket 21 moves forward and the left bracket 21 moves backward. I will have to move. As a result, the rear shaft 13 turns to the left via the leaf spring 20, and rear shaft steering is performed. Therefore, even in such an embodiment, it is possible to achieve the same effects as in the above embodiment. Furthermore, according to this embodiment, the rear shaft 13 can be steered simply by driving the geared motor 60 by the drive circuit 64, so that means for generating hydraulic pressure is not required.

〓Application example〓 The present invention has been described above with reference to an illustrated embodiment.
The present invention is not limited to the above embodiments, and various modifications can be made based on the technical idea of the present invention. For example, the present invention can be applied to a vehicle in which the rear axle is suspended by a suspension spring consisting of a combination of a leaf spring and an air spring.
It can also be used in vehicles in which the front end or rear end of the vehicle is connected to the frame by an air spring. Further, the rear end portion of the leaf spring 20 may be supported by a sliding seat instead of the shaft 23. Furthermore, in the second embodiment, the geared motor 60 that drives the feed screw may be replaced with a hydraulic motor. Furthermore, although the means for allowing mutual movement between the leaf spring and the axle is constituted by a rubber bush in the above embodiment, it may also be a pin joint.

〓Effects of the invention〓 As described above, the present invention is able to connect the rear shaft to the leaf spring through a permitting member that allows the intersection angle of the rear shaft to the leaf spring to be changed and allows the rear shaft to rotate in the yaw direction. At the same time, one end of the leaf spring is connected to the vehicle body via an actuator, and the left and right actuators move the left and right leaf springs in opposite directions. The rear axle rotates to perform steering.

Therefore, it is possible to configure the rear axle steering mechanism with a simple configuration and a small number of parts, and there is almost no increase in weight, providing a trailing steering device that is very advantageous in terms of cost. It becomes possible to do so.

By steering the rear axle with such a rear axle steering device, it is possible to improve the steering stability of the vehicle and the maneuverability of the vehicle.

In addition, since the axle is attached to the leaf spring through the permissible member, the connection between the axle and the leaf spring is ensured, which results in an extremely safe rear axle steering system. It becomes possible to provide

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a structure for moving the front bracket of a rear axle steering device according to a first embodiment of the present invention, FIG. 2 is a plan view of a truck equipped with this rear axle steering device, and FIG. The figure is the same side view, 4th
The figure is a plan view showing the suspension device on the rear side of this truck, FIG. 5 is a side view of the same, FIG. 6 is a longitudinal sectional view showing the support structure of the front bracket, and FIG. 7 is a front bracket according to a modified example. 8 is a front view of a modified rubber bushing, FIG. 9 is a sectional view taken along the line ~ in FIG. 8, and FIGS. 10 to 12 show the operation of this rear shaft steering device. Flowchart, FIG. 13 is a block diagram showing the structure of movement of the front bracket of the rear axle steering system according to the second embodiment. In addition, in the symbols used in the drawings, 10...frame, 13...rear shaft (drive shaft), 20...leaf spring, 21...front bracket, 22
...Eye pin, 23...Shackle, 24...Rear bracket, 25...Slide guide, 26...
...Torque closed, 27...Rubber bush, 28
...Connection bolt, 37...Hydraulic cylinder, 60...
...It is a geared motor.

Claims (1)

[Claims for Utility Model Registration] In a vehicle in which a rear axle is suspended by a suspension spring consisting of a leaf spring, an intersecting angle of the rear axle with respect to the leaf spring can be changed, and the rear axle is It is attached to the leaf spring through a permitting member that allows rotation in the yaw direction, supports the leaf spring so as to be movable in the longitudinal direction, and connects one end of the leaf spring to the vehicle body via an actuator, so that the leaf spring can be rotated from side to side. A rear shaft steering device for an automobile, characterized in that the left and right leaf springs are moved in opposite directions by an actuator, thereby turning the rear shaft to perform steering.