JPS6280168A - Rear axle steering device for automobile with rear double axles - Google Patents

Abstract

PURPOSE:To make possible to steer rear axles of a vehicle such as, for example, a two rear axle type truck, with a simple arrangement, by forming fluid chambers in each of couplings provided at both ends of each of torque rods for supporting the rear axles, and by feeding and discharging fluid into and from the fluid chambers to change the effective length of the torque rod. CONSTITUTION:In a rear axle steering device in which front rear and rear rear axles of a vehicle such as a truck or the like, are suspended from both ends of leaf springs, and both ends of the front rear and rear rear axles are coupled to a vehicle body through the intermediary of torque rods 26, respectively, ring-like couplings 33, 34 are provided at both ends of each torque rod 26, and are fitted therein with rubber bushings 35 each having its center section oscillatably supporting a connecting pin 37. Further, a pair of hydraulic chambers 41, 42 are formed in each rubber bushing 35 at positions on an axial extension of the torque rod 26, symmetrically with each other with respective to the center of the bushing, and therefore, the effective length L between the couplings 33, 34 is changed by feeding and discharging fluid into and from the hydraulic chambers 41, 42 through a change-over valve 38 to steer the rear axle.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a rear axle steering device for a two-axle rear vehicle, and particularly relates to a rear axle steering device for a rear two-axle vehicle. The present invention relates to a rear axle steering device for a rear two-axle vehicle in which a rear front axle and a rear axle are respectively suspended.

KSummary of the Invention The present invention provides a fluid chamber in at least one rubber bushing of the connecting portions at both ends of a torque rod that connects both sides of a rear-front axle and a rear-rear axle with the vehicle body, and a fluid chamber is provided in the rubber bushing of at least one of the connecting portions at both ends of a torque rod that connects both sides of a rear-front axle and a rear-rear axle with the vehicle body. The effective length between the connecting portions at both ends is changed by supplying or discharging the fuel, thereby turning the rear-front shaft and the rear-rear shaft to perform steering.

K. Prior Art Trucks have been widely used in the past to transport various types of cargo. As the load on the truck increases, the load applied to the rear axle in particular increases. In order to reduce the load applied to one axle, trucks with large payloads are now adopting a structure with two rear axles. Trunnion suspensions are widely used to distribute the load to each of the two rear axles.

[Problems to be solved by invention K] However, in conventional trucks, both the rear front axle and the rear axle, which constitute the two rear axles, are configured so that they cannot turn, and the wheels attached to these axles cannot rotate. was unable to steer the vehicle. However, the maneuverability of a vehicle changes depending on the vehicle speed. Alternatively, the maneuverability changes depending on the position of the cargo. Therefore, in order to maintain constant steering stability, it is preferable to make each of the two rear axles steerable. After 2
It is known that if both axles are made steerable, it is possible to reduce the minimum turning radius, reduce the difference between the inner and outer wheels, or reduce tire wear.

The present invention has been made in view of these problems, and is designed to prevent changes in steering stability due to changes in vehicle speed, the position of the live load, etc., and to obtain a certain level of steering stability. 2
The object of the present invention is to provide a rear shaft steering device for an axle.

Means for Solving Problem K] The present invention suspends a rear front axle and a rear axle by the front end and rear end of a leaf spring supported via a trunnion bracket, and In a vehicle in which both sides of the front axle and the rear axle are connected to the vehicle body via torque rods, a fluid chamber is provided in at least one rubber bushing of the connecting portions at both ends of the torque rod, The effective length between the connecting portions at both ends is changed by supplying or discharging fluid into the fluid chamber, thereby turning the rear-front shaft and the rear-rear shaft to perform steering.

Therefore, according to the present invention, by supplying or discharging fluid into the fluid chamber provided in the rubber bush of the torque rod, the effective length of both ends of the torque rod is changed, and the torque rod is connected. It becomes possible to perform steering by turning the rear-front axle and the rear-rear axle.

K Example] The present invention will be explained below with reference to an illustrated embodiment.

2 and 3 show a truck equipped with a rear wheel 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-front shaft 13 and a rear-rear shaft 14. Here, the rear and front axles 13 constitute a driving shaft, and the rear and rear axles 14 constitute a driven wheel or a base shaft.

Next, the structure of the suspension of these two rear axles 132.14 will be explained. As shown in FIGS. 4 and 5, trunnion brackets 20 are fixed to each of the left and right frames 10, and these trunnions The bracket 20 allows the trunnion shaft 21 to be mounted perpendicular to the frame 10.

Spring seats 22 are rotatably attached to both ends of the trunnion shaft 21, respectively. Furthermore, this spring seat 22 supports a leaf spring 23 that constitutes a suspension spring via a U bolt 24.

The rear-front shaft 13 is suspended on the front end of the leaf spring 23 supported in this way, 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 shafts 130 are connected to the trunnion brackets 20 through the 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 on both sides is connected to the trunnion bracket 20 by left and right torque rods 26, 27. It has become so.

To explain in more detail the torque rods 26 and 27 that connect these to the vehicle body at both ends of the rear and front @13 and the contact @14, as shown in FIG. Ring-shaped connecting portions 33 and 34 are formed at both ends, respectively. These connections 33, 34 have circular openings in their centers and receive rubber bushings 35. A joint ring 36 is supported on the center side of the rubber bush 35, and supports the connecting pin 37 so as to be swingable.

Inside the rubber bush 35, a pair of hydraulic chambers 41, 42 are provided symmetrically with respect to the center at positions on the axial extension of the torque rods 26, 27. These hydraulic chambers 41, 42 are connected to the switching valve 38 via an oil conduit. The switching valve 38 is further connected to three oil pumps and a reservoir 40.

An actuator 46 for switching the spool of the switching valve 38 is controlled by a microcomputer 47. The input side of the microcomputer 47 is connected to a steering angle sensor 49 that detects the steering angle of the steering wheel 48, a vehicle speed sensor 50, a yaw rate sensor 51, a lateral acceleration sensor 52, and a stroke sensor 53. There is.

In the above configuration, the rear-front shaft 13 and the rear-rear shaft 1
4 to the frame 10 via trunnion brackets 20 at both ends thereof.
As shown in FIG. 1, hydraulic chambers 41 and 42 are provided in the left and right connecting portions 33 and 34, respectively. Therefore, pressurized oil is supplied to the hydraulic chamber 41 of the left connecting portion 33 and the hydraulic chamber 41 of the right connecting portion 34, respectively.

When the oil is discharged from the hydraulic chambers 42 of the coupling parts 33 and 34, the joint rings 36 engaged with the coupling bottle 37 move in a direction away from each other.
This increases the distance between the centers of the connections al 133.34 and causes the torque rods 26.27 to extend. On the other hand, by supplying oil into the hydraulic chamber 42 of the coupling part 33.34 and discharging oil from the other hydraulic chamber 41, the distance between the centers of the coupling part 33.34 is shortened. and a pair of left and right torque rods 26.
By lengthening one of the torque rods 27, for example, the left torque rod 26, and shortening the right torque rod 27, it is possible to turn the axle to which these torque rods 26, 27 are connected to the right. , this results in steering of the rear axle. In this embodiment, the rear-front shaft 13 and the rear-rear shaft 14 are each independently steered. Also, the rear front axis 13
Lateral displacement of the rear shaft 14 is prevented by a pair of upper torque rods 25 disposed in an upper V-shape.

The control for the two-axis steering by the microcomputer 47 will be explained in more detail.As shown in the flowchart shown in FIG. 6, 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 and front axles 13 is calculated using these values.

Furthermore, the steering angle of the rear and front shafts 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-front shaft 13 is further turned and steered.

On the other hand, if the S1 calculated value is smaller, the rear-front axis 1
3 in the direction of return.

The microcomputer 47 also performs such control for the eleventh axis 14. That is, the steering angle of the rear axle 14 is calculated, and the actual steer angle of the rear axle 14 is read. Then, the calculated value is compared with the actual steering angle, and if the calculated value is larger, the rear axle 14 is further steered, whereas if the calculated value is smaller, the rear axle 14 is further steered. I'm trying to get it back. Therefore, by such control, the rear-front axle 13 and the rear-rear axle 14 are respectively steered to steering angles corresponding to the vehicle speed.

Furthermore, this rear axle steering system maintains constant steering stability by steering the two rear axles in response to changes in vehicle speed and load.

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-front axle 13 and the rear-rear axle 14 are connected to the torque rods 26.
Steering correction is performed by supplying or discharging oil to hydraulic chambers 41, 42 provided at 7.

Note that instead of the steering correction based on the yaw rate, it is also possible to perform the steering correction quickly upon detection of the 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 lateral acceleration is read by the Henry-52 (the actual lateral acceleration that is passed), and a comparison is made between the above calculated p value and the actual lateral acceleration. If the value exists,
The torque rods 26 and 27 are expanded and contracted by the hydraulic cylinders 37 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. In addition, the steering stability changes depending on the position of the cargo, and furthermore, the vehicle receives lateral forces due to 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 independently steering the rear-front axle 13 and the rear-rear shaft 14 using the devices shown in FIG. 1, making it possible to maintain a constant level of steering stability. Become. 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.

Although the present invention has been described above with reference to the illustrated embodiment, 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 hydraulic chambers 41, 42 are provided at the connecting portions 33, 34 at both ends of the torque rod 26, 27, respectively. may be provided. This reduces the change in the effective length between the connecting portions 33 and 34 to half that of the above embodiment, but such a configuration can also be used if the steering angle is small.

Effects of the Invention] As described above, the present invention provides a fluid chamber in at least one rubber bushing of the connecting portions at both ends of the torque rod,
By supplying or discharging fluid to or from the fluid chamber, the effective length between the connecting portions at both ends is changed, thereby steering the vehicle while avoiding turning the rear-front shaft and the rear-rear shaft. 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 vehicle speed, cargo position, or disturbance. Furthermore, such rear axle steering makes it possible to reduce the minimum turning radius, reduce the difference between the inner and outer wheels, and reduce the amount of tire wear.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an I-structure for changing the effective length of the connecting portion of the torque rod of a rear axle steering device according to an embodiment of the present invention, and FIG. 2 is a plan view of a truck equipped with the rear axle steering device. Fig. 3 is a side view of the same, Fig. 4 is a side view showing the suspension device of the rear two axles of this truck, Fig. 5 is a front view of the same, and Figs. 6 to 8 show the operation of rear axle steering. The flow chart shown in FIG. 9 is a plan view showing a suspension device for two rear axles. In addition, in the symbols used in the drawings, 10... Frame 13... Rear front @ (drive shaft) 14... Rear @ (driven shaft, main shaft) 20... Trunnion bracket 21... Trunnion shaft 23...Leaf spring 26.27...Torque rond 33.34...Connection part 35...Rubber bush 36...Joint ring 37...Connection pin 38...Switching valve 39... Oil pumps 41, 42...Hydraulic chamber 46...Actuator 47...Microcomputer 49...Steering angle sensor 50...Vehicle speed sensor 51...Yaw rate sensor 52...Lateral acceleration 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 a vehicle in which a fluid chamber is provided in at least one rubber bush of the connecting portions at both ends of the torque rod, and by supplying or discharging fluid into the fluid chamber, the connection between the connecting portions at both ends is 1. A rear shaft steering device for a rear two-axle vehicle, characterized in that the effective length of the rear shaft is changed, thereby turning the rear-front shaft and the rear-rear shaft to perform steering.