JPS62194974A - Rear axle steering device for two rear shaft vehicle - Google Patents

Abstract

PURPOSE:To steer a rear axle by connecting a torque rod connected with the both sides of a rear front axle and a rear rear axle with a trunnion bracket through a feeding screw. CONSTITUTION:The output shaft of a motor 33 fixed with a trunnion bracket 20 is constituted of a feeding screw 34 and extended to the both sides of the motor 33. The feeding screw 34 extended forward is engaged with a torque rod 27 on a rear front axle 13 side, and the feeding screw 34 extended rearward is engaged with a torque rod 27 on a rear rear axle 14 side. Said torque rod 27 is transferred by the feeding screw 34 so that the extension and contraction are reversed on the right and left of a vehicle, and steering for two rear axles is performed.

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a one or two-axle steering system for a vehicle with two rear axles, and more particularly to a one- or two-axle steering system for a vehicle in which the two rear axles are suspended by a trunnion suspension system. Summary of the Invention The present invention connects torque rods connected to both sides of a rear-front shaft and a rear-rear shaft to a trunnion bracket via a feed screw, and drives the rear-front shaft by driving the feed screw. And the rear axle is turned to perform steering. ``Conventional technology 1'' Trucks have been widely used in the past to transport various types of cargo.As the carrying load increases, the load applied to the rear axle in particular increases. In order to reduce the load -46, in trucks with large carrying loads, a structure of two rear axles) Δ is adopted.In order to distribute the load to each of these two axles, 1 to 11 runion suspensions are widely used.Problems to be solved by the K inventionHowever, in conventional trucks, both the front and rear axles, which make up the two axes, are configured so that they cannot rotate. The wheels attached to these axles could not be steered. However, the steering stability of the vehicle changes depending on the vehicle speed. Also, the steering stability changes depending on the position of the cargo. In order to improve and maintain constant steering stability, it is preferable to make each of the two rear axles steerable.Roughly, if both rear axles are made steerable, the minimum turning radius can be reduced. It is known that it is possible to reduce the difference between the inner and outer wheels, or to reduce tire wear.The present invention was made in view of these problems, and it improves steering stability. In addition, the rear axle steering system of two-axle vehicles is used to prevent changes in steering stability due to changes in vehicle speed (5), such as the position of the loaded load, and to obtain a certain level of steering stability. [Means for Solving Problem K] The present invention has the following features: (1) The front end and the rear end of a leaf spring supported via a runni A bracket are connected to a rear-front shaft. J3 is installed in a vehicle in which the rear and rear axles are suspended, and both sides of the rear and front axles are connected to the 1 to runner brackets 1 via torque rods, respectively. A torque rod connected to both sides of the shaft J3 and the rear-rear shaft is connected to the I-runion bracket via a feed screw, and the rear-front shaft and the rear-rear shaft are rotated by driving the feed screw. Therefore, according to the present invention, the rear-front shaft J3 is controlled by the feed screw interposed between the trunnion bracket and the torque rod.
This makes it possible to perform steering by turning the front and rear axles respectively. For example, even if the steering stability changes due to changes in vehicle speed or the position of the loaded load, the hydraulic cylinder is activated to counteract this change. By rotating the rear-front axle and the rear-rear axle, it becomes possible to perform steering correction to improve steering stability and to maintain it constant. K Embodiment The present invention will be described below with reference to the illustrated embodiment. FIGS. 2 and 3 show a truck equipped with a rear axle steering device according to a first 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 of the frame 1o. The front end side of the frame 10 is supported by a front shaft 12, and the rear side is supported by a rear-front shaft 13 and a rear-rear shaft 14. Here, the rear-front shaft 13 constitutes a drive shaft, and the rear-rear shaft 14 constitutes a driven shaft or an original shaft. Next, to explain the structure of the suspension of these two rear axles 13 and 14, as shown in FIGS. 4 and 5, trunnion brackets 20 are fixed to each of the left and right frames 1o, and these trunnions 1-run shaft 21 by bracket 20
is attached so as to be perpendicular to the frame 1o. Spring seats 22 are rotatably attached to both ends of the trunnion shirt 1-21. Furthermore, this spring seat 22 has a leaf spring 23 (
J Pol)-24. The rear-front shaft 13 is suspended on the front end of the leaf spring 23 supported in this manner, and the rear-rear shaft 14 is suspended on the rear end. and rear front axis 1
The upper central parts of 3 are connected to each other by V as shown in FIG.
It is connected to a cross member 28 that connects the left and right frames 10 by a pair of torque rods 25 arranged in a letter shape. On the other hand, both sides of the rear and front axle 13 are connected to trunnion brackets 20 through lower torque rods 26 and 27, respectively.
It is now connected to The upper center of the rear axle 14 is also connected to the cross member 28 by a torque rod 25, and the lower side of the rear axle 14 and both sides are connected to the 1-runion bracket 20 by left and right torque rods 26 and 27. It is now connected. Next, the structure of the connection between the torque rods 26, 27 and the trunnion plano knot 20, which are connected to the left and right sides of the axle 13, 14, respectively, will be explained.
An electric motor 33 is fixed to the trunnion bracket 20. As shown in FIG. 1, this motor 33
The output shaft is composed of a feed screw 34 and extends to both sides of the motor 33. The feed screw 34 extending forward is engaged with a female screw hole of a bracket 36 connected to the torque rod 27 on the rear-front shaft 13 side, and the feed screw 34 extending rearward is engaged on the rear-rear shaft 14 side. The torque rod 27 of the bracket 36 is connected to the internal screw hole of the bracket 36. The motor 33 is driven by a drive circuit 45. A drive circuit 45 for driving the motor 33 is controlled by a microcomputer 47. The input side of this microcomputer 47 is a steering angle sensor 4 that detects the steering angle of the steering wheel 48.
9, a vehicle speed sensor 50, a yaw rate sensor 51, and a lateral acceleration sensor 52, respectively. Next, to explain the steering operation of this rear axle steering device configured as described above, the drive U circuit 45 is controlled by a control signal from the microcomputer 47 shown in FIG.
By driving the motor 33 through the motor 33, it is possible to rotationally drive the feed screw 34 that constitutes the output shaft of the motor 33, and thereby the torque rod 26.2
7 can be moved individually. The connections between the left and right motors 33 and the drive circuit 45 are reversed. Therefore, according to such a configuration, the left and right torque rods 26 and 27 corresponding to H are moved by the feed screw 34 so that their expansion and contraction are reversed. Therefore, for example, when moving the bracket 36 connected to the left torque rod 27 forward and moving the bracket 36 connected to the right torque rod 26 backward, the 1!2 front shaft 13 and the rear The rear axle 14 is turned to the right by the same angle, and the two rear axles are thereby steered. And inoculation @
13 and the rear-rear axis 14 are caused by the upper pair of Vs.
This is prevented by the torque rods 25 arranged in a letter shape. To explain in more detail the control for the two-axis steering by the microcomputer 47, as shown in flowchart 1- shown in FIG.
The steering angle of the steering wheel 48 is read by the sensor 49. Next, the vehicle speed is read by the vehicle speed sensor 50, and based on these values, the steering angles of the rear and front axles 13J3 and the rear and rear axles 14 are calculated. The steering angles of the rear-front axle 13 and the rear-rear shaft 14 are roughly read by the steering sensor 53. This actual steering angle is then compared with the steering wheel value. If the total value is larger, the rear axle 13, 14 is further turned and steered. On the other hand, if the total value is smaller, the rear shafts 13 and 14 are returned to their original states. Furthermore, in this rear axle steering system, by steering the rear 2@b according to changes in vehicle speed and load,
I try to maintain stable handling. This operation is shown in Figure 8.

[This is carried out based on the flowchart shown here.] 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 1- is compared with the standard yaw rate, and if the actual yaw rate is outside the standard yaw rate, the rear-front shaft 13 and the rear @14 are moved to the torque rod 26.
．． Steering correction is performed by rotating and turning the feed screw 34 connected to the steering wheel 27. Instead of the steering correction based on the J3 yaw rate, it is also possible to perform the 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 into the four steering angle sensors as J:, and the standard lateral acceleration at this steering angle is calculated. j Now. Then, the actual lateral acceleration obtained by the lateral acceleration sensor 52 is read, and the calculated value and the actual lateral acceleration are compared. If the actual lateral acceleration value is outside the range of the standard lateral acceleration,
The torque rods 26 and 27 are moved by the feed screw 34 to perform steering correction by turning the rear-front shaft 13 and the rear-rear shaft 14. Generally, the yaw rate or lateral acceleration of a vehicle changes depending on the vehicle speed. Furthermore, the steering stability changes depending on the position of the cargo, and furthermore, the vehicle receives lateral forces due to external disturbances such as cross winds and road slopes, which causes the steering stability to change. However, such changes in steering stability can be corrected by steering the rear-front shaft 13 and the rear and rear shafts 14 using the devices shown in FIG. 1, thereby making it 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 two rear axles in this manner, the minimum turning radius can be reduced, the difference between the inner and outer wheels can be reduced, and the wear of the tires on the rear front axle 13 and the rear axle 14 can be particularly reduced. It becomes possible to reduce the amount. Roughly speaking, according to the rear axle steering system according to this embodiment, the rear front axle 13 and the rear axle 14 are turned as a whole, and the rear axle is connected to one shell and two axles 13 and 14. The structure is different from MA construction, in which the steering wheel is rotatably supported by a kingpin for steering. That is, the rear-front shaft 13 and the rear-rear shaft 14 are made movable in the front-rear direction with respect to the leaf spring 23, and the rear-front shaft 13 and the rear-rear shaft 14 can be turned as a whole. Therefore, it is possible to perform rear two-axle steering with a very simple structure, and the number of parts required for this purpose is small, there is almost no increase in weight, and the rear axle steering device is configured very cost-effectively. It becomes possible to do. Next, a second embodiment of the present invention will be explained with reference to FIG. In this second embodiment, parts corresponding to those in the first embodiment shown in FIG. 1 are given the same reference numerals, and
Descriptions of parts with the same configuration will be omitted. The features of this second embodiment include the rear-front shaft 13 and the rear-rear IM 14.
The feed screw 34 for turning the shaft is driven by a hydraulic shaft 35. The hydraulic motor 35 is connected to an oil pump 39 via a switching valve 38, and the oil pump 39 sucks oil from a reservoir 40. and switching valve 38
The spool is moved by an actuator 46, and this actuator 46 is controlled by a microcomputer 47. Furthermore, the connections between the left and right hydraulic motors 35 and the switching valves 38 are reversed. Therefore, by switching the switching valve 38 via the actuator 46 based on instructions from the microcomputer 47, the feed screw 34 is driven by the hydraulic motor 35 on the right side, and the bracket 36 is moved forward, and the bracket 36 on the left side is moved forward. 36 is 1v by the feed screw 34! It will be moved towards As a result, both the rear-front shaft 13 and the rear-rear shaft 14 turn leftward, resulting in rear 2@ steering. Therefore, such an embodiment can also achieve the same effects as the above embodiment. Further, according to this embodiment, since the hydraulic motor 35 is used as the drive source for the feed screw 34, a large driving force can be generated, and the rear axle steering of a vehicle with a large load can be achieved. It becomes possible to do so. K Application Example The present invention has been described above with reference to the illustrated embodiment, but the present invention is not limited to the above embodiment, and various modifications can be made based on the technical idea of the present invention. For example, in the above embodiment, the front and rear torque rods on the left and right sides are moved together by the feed screw 34 that constitutes the output shaft of a common motor 33, 35, but the rear and front shafts 13 and the rear The torque rods respectively connected to the rear shaft 14 may be separately connected to the trunnion bracket via two mutually independent motors and feed screws. According to such a configuration, it becomes possible to steer the rear-front shaft 13 and the rear-rear shaft 14 to different steering angles. [Effects of the Invention] As described above, the present invention connects the torque rods connected to both sides of the rear-front shaft and the rear-rear shaft to the trunnion bracket 1 via a feed screw, and drives the feed screw. The rear shaft and the rear shaft are rotated to perform steering. Therefore, according to the present invention, rear axle steering is possible with a simple configuration, and automatic corrective steering can be performed in response to changes in vehicle speed, load position, or external disturbances. In addition, such rear wheel steering reduces the minimum turning radius, reduces the difference between the outer and inner wheels, and
It becomes possible to reduce tire wear.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a structure for operating a feed screw connected to a torque rod of a rear wheel steering device according to a first embodiment of the present invention, and FIG. 2 is a block diagram of a truck equipped with a rear wheel steering device. A plan view, Figure 3 is a side view of the same, Figure 4 is a side view of the rear two axles of this truck, and Figure 5 is a side view.
The figure is a front view of the same, FIG. 6 is a plan view of the same, FIGS. 7 to 9 are flowcharts showing the operation of rear axle steering, and FIG. 10 is a block diagram of a rear wheel steering device according to a second embodiment. be. Note that the reference numbers used in the drawings are J3, and 10...Frame 13...Rear-front shaft (drive shaft) 14...Rear-rear shaft (driven shaft, base shaft) 20...1-Runion bracket 21. ... Trunnion shaft V 1-23 ... Leaf spring 26.27 ... Torque rod 33 ... Electric motor 34 ... Feed screw 35 ... Hydraulic motor 36 ... Connection bracket 38 ... Switching valve 39...Oil pump 45...Drive circuit 46...Actuator 47...Microcomputer 49...Steering angle sensor 50...Vehicle speed sensor 51...Yaw rate sensor 52...Lateral acceleration It is a sensor.

Claims (1)

[Claims] A rear front shaft and a rear rear shaft are respectively suspended by the front end and rear end of a leaf spring supported via a trunnion bracket, and torque rods are respectively connected to both sides of the rear front shaft and the rear rear shaft. In the vehicle, the trunnion bracket is connected to the trunnion bracket via a feed screw, and the torque rods connected to both sides of the rear front axle and the rear axle are connected to the trunnion bracket via a feed screw, and the feed screw is driven. A rear shaft steering device for a rear two-axle vehicle, characterized in that the rear-front shaft and the rear-rear shaft are turned to perform steering.