JPS59199372A - Steering system used for rear two-axle type vehicle - Google Patents

Abstract

PURPOSE:To improve the turning performance, as well as the stability in running, by controlling a rear steering on the basis of a vehicle speed and the steering amount of front wheels so that it is put in a steering state according to a prescribed turning pattern or in a fixed state. CONSTITUTION:A steering system has a front steering 11 for front wheels 59 and 60 operated by a steering wheel 19 through the intermediary of a power steering device 21, and a rear steering 26 for rear wheels 65 and 66. The rear steering 26 has, as a driving source, a hydraulic actuator 36 whose output is controlled by a control valve 44, which is opened and closed by a pulse motor 45 controlled by a control unit 40. The control unit 40 receives as an input the respective output of a vehicle sensor 41 and a steering amount sensor 42 detecting the steering amount of the front wheels 59 and 60, and controls a pulse motor 40 to turn the rear wheels 65 and 66 according to a prescribed turning pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steering system used in rear two-axle vehicles such as large trucks, heavy trucks, and rough terrain trucks.

In general, heavy trucks and rough terrain trucks have been constructed with a rear axle as a tandem axle, that is, a rear front axle and a last axle, to reduce the axle load of the truck. Further, in the rear two-axle type truck, either a -shaft drive or a two-shaft drive is adopted, but neither of these two axles is steered and is placed in a fixed state.

In such a rear two-axle type truck pick-up, running stability is improved, but when turning, the rear wheel attached to the last axle may skid, causing significant wear on the tires on the rear wheels. ,
Further, since then, the minimum turning radius of two-axle trucks has tended to be relatively larger than that of normal trucks.

Also, if the rear wheels attached to the last axle of the various rear two-axle trucks are self-steering,
Although the minimum turning radius of the truck can be reduced and significant wear of the rear tires can be prevented, running stability at high speeds is impaired.

In other words, when the front wheel attached to the frontmost axle is steered by the front steering wheel, the front wheel
Since the truck is not steered in proportion to the steering angle but in proportion to the magnitude of lateral acceleration, there is a risk that the truck will oversteer.

The purpose of this invention is to reduce the turning radius when turning at low speeds, alleviate tire skidding, prevent significant tire wear, and improve turning performance when driving at high speeds. The steering system used in rear two-axle vehicles improves running stability and makes turns safer when turning at high speeds1.In addition, it simplifies the steering control system and stabilizes the control. On offer.

Another object of the present invention is to reduce skidding of tires when turning at medium speeds, prevent significant tire wear,
To provide a steering system used in a rear two-axle type vehicle that enables safe turning and improves running stability at medium speeds.

With these problems in mind, the steering system used in the rear two-axle vehicle of the present invention first includes a front steering system that is then placed in front of the two-axle vehicle and that steers the front wheel axle of the front wheel, and and is equipped with a hydraulic actuator and a control pulp for the hydraulic actuator reservoir, and is located behind the last axle.
It is equipped with a rear steering wheel that steers the rear wheel axle, a steering wheel motor that drives its control pulse, a vehicle speed sensor, and a steering amount sensor placed on the front steering wheel.
In relation to steering, it has a built-in nine predetermined turns for turning the wheel axle, and the pulse motor is driven according to the signals from the vehicle speed sensor and the steering amount sensor to adjust the turning turns. Steering status according to 4 turns,
(Con) so that the wheel axle is then in either a fixed state.

- Le Pal 7' All controls consist of a control unit.

Further, the steering system used in the rear two-axle type vehicle of the present invention steers the rear wheel axle in relation to the front wheel axle during low speed driving, and furthermore, as the driving speed increases, the steering system steers the rear wheel axle in relation to the front wheel axle. After that, the steering ratio of the wheel axle is reduced and the tendency of amplifier steering is strengthened.Front steering is then placed at the front of a two-axle type vehicle and steers the front wheel axle of the front wheel, and the rear steering wheel of the vehicle a rear wheel shaft for steering the rear wheel axle for the rear wheel of the last axle; A predetermined turn A? comprising a pulse motor, a vehicle speed sensor, and a steering amount sensor disposed on its front steering, and associated with said front steering, after which the wheel axle is to be steered. The pulse motor is driven according to the signals from the vehicle speed sensor and the steering amount sensor, and the steering state according to the turning pattern, the fixed state, and the fixed state are determined based on the predetermined steering amount. and a control unit which controls its control valves so that the wheel axle is then placed in either a steered or steered state.

The important advantages provided by the steering system for use in the rear two-axle vehicle of the present invention constructed as such are as follows:
When a rear two-axle type vehicle turns at low speed, the rear wheels of the last axle are steered according to signals from the vehicle speed sensor and the steering amount sensor according to a predetermined turning pattern, so that the turning of the vehicle is controlled. If the radius is small, the tires of the vehicle have very little side slippage, especially the rear wheels on the last axle, significant tire wear is prevented and turning performance is improved. Also, when the vehicle is running at high speed, the last axle and rear wheels are in a fixed state, so running stability is improved, and
When the vehicle is turned at high speeds, the tendency of the vehicle to oversteer is avoided, making the turn safer; and when the vehicle is turned at medium speeds, the tendency of the front wheel axle to When the steering angle is within a predetermined angle, the rear wheel axle is kept in a fixed state, and when the steering angle of the front wheel axle exceeds the predetermined angle, the wheel axle is then steered in relation to the front wheel axle. Therefore, the skidding of the rear wheels is reduced, significant wear of the tires is prevented, and safe turning is possible.In this way, turning performance and running stability are improved, and skidding of the rear wheels when turning is reduced. Since the distance between the front and rear axles and the last axle can be increased, even when driving on rough roads,
This prevents the wheels from slipping and distributes the load evenly on both axles.
The design conditions to always equalize the ground load have been relaxed,
Vehicle design becomes easier.

Therefore, this invention certainly applies to rear two-axle vehicles,
For example, heavy trucks, rough terrain trucks.

It is useful and suitable as a steering device for large buses, etc.

Hereinafter, preferred specific examples of the steering system used in the rear two-axle vehicle according to the present invention will be described with reference to the drawings.

Figures 1 and 2 show the frontmost axle 14.15 and the rear front axle 57.
．． 58. 10 schematically shows a specific example 10 of the steering system of the present invention applied to a rear two-axle bus 50 having a rear axle 29, 30.

This steering system 10 is arranged in front of the rear two-axle bus 50, and includes a linkage type power steering device 2.
1, a front steering wheel 11 for steering the front wheel axle 14.15 of the front wheel 59.60 by operation of the steering wheel 19, and a hydraulic actuator located at the rear of the bus 50. control valve 4 for 36 and its actuator 36
4 and steering the rear wheel axle 29.30 for the rear wheels 65.66 of the rearmost axle 53;
No' to drive that control valve 44? Luz
A motor 45 and a vehicle speed sensor 41. and a steering amount sensor 42 disposed on the front steering wheel 11, and in connection with the front steering wheel 11, it incorporates a predetermined turning angle for subsequently steering the wheel axle 29,30. , its vehicle speed sensor 41. In response to the signal from the steering amount sensor 42, the motor 45 is driven and the control is performed so that the wheel axle 29. The control unit 40 controls a valve 44.

That is, the rear two-axle bus 50 to which the steering system used for the rear two-axle vehicle of the present invention is applied has front wheel axles 57 .
58 is driven by an engine (not shown) mounted at the rear of the bus 50, and the front wheel axle 14.15 for the front wheels 59.60 is connected to the steering wheel 1.
Furthermore, when the bus 50 travels at low speed, the rear wheel axle 29.30 for the rear wheels 65.66 of the last axle 53 follows a predetermined turning pattern and the front wheel axle 14. Steered in connection with 15;
Further, when the path 50 travels at high speed, the wheel axles 29, 30 are configured to be held in a fixed state thereafter.

The front steering 11 has a front wheel axle of 14°15,
and a tie rod arm 16.17, each rotatably mounted via a king pin 24.25 at each end of a front axle beam 52 located forward of the chassis frame 51 of its path 50. A pair of knuckles attached 12.13. That tie rod
Tie rods 18 connecting the arms 16, 17 ends to each other
, linkage type power valve with control valve.
Steering device 21, its steering wheel 1
The steering shaft 20 and its control valve are connected to each other so as to transmit the operating force of the steering shaft 20 to its convex control valve.
A connecting mechanism 22 connecting the valve to the knuckle 13 is formed integrally with the knuckle 13 so as to drive the knuckle 13, and is connected to the operating rod end of the power cylinder in the i9 war steering device 21. Link·
The lever 23 includes a hydraulic power supply source (not shown) for the power steering device 21, and so on.

Its front steering 11 is configured substantially identically to the steering applied to the existing path;
A description of the components of the front steering wheel 11 will be omitted.

Of course, the first front wheel axle 14.15 has a front wheel of 59°60
are attached to each.

Therefore, upon operation of the steering wheel 19, the power steering device 21 causes the knuckles 12, 13 to rotate in the same direction, causing the front wheel axle 14 to rotate.
．． 15 is steered, and the steering angles of its front wheels 59, 60 are changed.

Of course, although the four-wheel steering device 21 has been described as a linkage type device, it is also possible to use an integral type or semi-integral type.

The rear front axle wheels 61, 62, 63, 64 and the front wheel axle 57.58 are connected to the chassis frame 51 in its path 50.
It is arranged at a position near the rear of the path 50, and is configured to be driven by an engine (not shown) mounted on the path 50.

The rear steering 26 steers the rear wheel axles 29, 30 and tie rod arms 31, 32,
Rotating via king bins 34 and 35 at both ends of the rear axle beam 53 located at the rear of the chassis frame 51 of the path 50, that is, also at the rear of the front wheel axle 57 and 58 mentioned above. Possibly 1. a pair of attached knuckles 27, 28, a tie rod 33 connecting the ends of the tie rod arms 31 and 32 to each other;
Hydraulic actuator 3 that drives the tie rod 33
6, and a control valve 44 for the hydraulic actuator 36.

The actuator 36 consists of one hydraulic cylinder), a connecting rod 38 fixed to one end of the cylinder 37 so as to be substantially perpendicular to it, and a piston fitted in the cylinder 37 so as to be able to reciprocate and slide. (not shown), and an operating rod 39 whose one end can be taken in and out from the other end of the cylinder 37 and whose other end is connected to the piston.

Of course, the cylinder 37 is provided with a pair of ports 67, 68 on one side, each communicating with a cylinder chamber (not shown) on either side of the piston.

The actuator 36 configured in this way is (-(7
) The operating rod 39 end is rotatably connected to the rear axle beam 53, and the connecting rod 38 end is rotatably connected to the tie rod 33.

The control valve 44 is disposed on its rear axle beam 53 and is of the tandem center type with a flow valve, and is provided with a pump port 69 and a pair of hydraulic ports 70, 71, respectively, which will be described later. /eRus・
The motor 45 is configured to slide the spool to switch the flow of pressure oil from the pump port 69 to the hydraulic port 70,71.

Accordingly, the pump port 69 of the control valve 44 is connected to an oil pump (not shown) via the hydraulic line 46, and the hydraulic port 70.71 is
Its actuator 36 via hydraulic piping 47', 48
are connected to a pair of ports 67 and 68, respectively.

Of course, the oil pump is driven by the engine mounted on the bus 50.

The iE Lux motor 45 is of the linear type and has controls for controlling the spool of the pulp 44 and for switching the flow of pressure oil from its pump port 69 to its hydraulic port 70,71. It is attached to the control valve 44. Of course, the i4 Luss motor 45 may be of a rotary type in addition to the linear type, as long as it slides its spool in response to a signal from the control unit 40, which will be described later. .

Therefore, if the pulse motor 45 is driven,
The spool of the control valve 44 is slid to either side, and in response to the movement of the spool, the actuator 36 is actuated, resulting in the above-mentioned knuckle 2.
7.28 rotates in the same direction, then the wheel axle 29.30
is steered, and then the steering angles of the rear wheels 65, 66 attached to the wheel axles 29, 30 are changed.

The control unit 40 includes a vehicle speed sensor 41 and a steering amount sensor 42 disposed around the steering shaft 20 in the front steering wheel 11, and in relation to the front steering wheel 11, the steering wheel The vehicle speed sensor 4 incorporates a predetermined turning pattern for steering the shaft 29,30.
1. Drive the four-wheel motor 45 according to the signal from the steering amount sensor 42, and control it so that the wheel axle 29° 30 is then placed in either the steering state or the fixed state according to the turning pattern. It controls the group 44 and mainly consists of an input and output circuit, an arithmetic circuit, a memory circuit, a control circuit, and a power supply circuit.

The vehicle speed sensor 41 is configured to detect the traveling speed of the bus 50 and send an electrical signal according to the speed, and connects the speed meter cable (not shown) of the bus 50 to the speedometer cable (not shown). ) and electrically connected to the input circuit of the control unit 40.

The steering amount sensor 42 detects the rotation speed, rotation direction, and rotation angle of the steering shaft 20 in the above-mentioned front steering 11. and its control unit 4
It is electrically connected to the input circuit of No. 8.

Of course, it is preferable that the steering amount sensor 42 has high resolution as a rotation sensor, consumes little power, and generates a reliable and large signal as an output. Semiconductor-type devices equipped with such devices are used.

Further, the above-mentioned pulse motor 45 is driven in accordance with a signal from the control unit 40.
Of course, it is electrically connected to the output circuit of the control unit 40.

Therefore, the control unit 40 always inputs the signal from the vehicle speed sensor 41, and when the /s'1 vehicle 50 is traveling at low speed, inputs the signal from the steering amount sensor 42, and performs a predetermined turning turn. Then wheel axle 2 according to
The control valve 44 is controlled so that the 9.80 is steered following its front wheel axle 14.15, and when the nose 50 is running at high speed, the wheel axle 29.30 is then steered. The control valve 44 is configured to hold the actuator 36 fixed, in other words, to lock the piston of the actuator 36 in a substantially neutral position.
control.

Of course, the control unit 40 stores a predetermined turning pattern based on the Atsukerman system in a memory circuit, and adjusts the running speed of the bus 50 and the steering angle of the front steering wheel 11 based on the turning pattern. Rear steering 26 depending on shaft 200 rotation speed 9 rotation direction and rotation angle
The steering direction and steering angle of the rear wheel axle 29, 30 are determined.

Next, we will discuss the running of the two-axle bus 500 to which the above-mentioned steering system IO is applied. When the bus 50 is running, a signal from the vehicle speed sensor 41 is constantly input to the control unit 40.

When the bus 50 is running at low speed, the steering
When the front wheel axle 14.15 is steered by operating the wheel 19, the steering amount sensor 42 detects the rotation speed, one rotation direction, and rotation angle of the steering shaft zO, and sends an output signal to its control unit). Send to 40.

The control unit 40 controls the steering wheel O motor 45tJllL and the control pulp 44 in response to the output signal based on the pre-stored turning number of turns.As a result, the actuator 36 is driven and the rear steering wheel 26 The rear wheel axle 29,30 of is steered.

For example, if the front steering wheel is steered to the left in order to turn the bus 50 to the left,
The rear steering wheel 26 is steered to the right at a predetermined steering angle to reduce the turning radius.

Therefore, when the bus 50 is running at low speed, the turning radius is small, and the rear wheel 65 on the rear steering 26 side
, 66 is prevented, and turning performance is improved.

Further, when the bus 50 is traveling at high speed, the control 6 unit 4o controls the control valve 44 in accordance with the output signal from the vehicle speed sensor 41, and moves the piston in the actuator 36 to a substantially neutral position. to lock.

That is, the rear wheel axles 29, 30 of the rear steering wheel 26 are held fixed.

Therefore, the running stability of the bus 50 at high speeds is improved, and safe turning is possible by steering the front steering wheel 11.

Furthermore, when the bus 50 is traveling at a medium speed, the rear wheel axle 29.30 of the rear steering z6 in the specific example 10 described above is adjusted when the steering angle of the front wheel axle 14.15 is within a predetermined angle. , is placed in a fixed state and is preferably configured to be steered with respect to its front wheel axle 14.15 if the steering angle of its front wheel axle 14.15 exceeds a predetermined angle.

If so configured, when the bus 50 is running at medium speed and the front wheel axle 14.15 is steered within a relatively small steering angle, ie within a predetermined steering angle, then the wheel axle 29. 30 is placed in a fixed state to ensure running stability.

Also, when the bus 50 is running at medium speed, the front wheel axle 14.
If 15 is steered through a relatively large steering angle, ie beyond a predetermined steering angle, then the wheel axle 29.30 is steered in relation to its front wheel axle 14.15, resulting in less tire wear. Also, the turning radius is small, and the turning performance is improved.

As mentioned above, when compared with the steering systems that have already been proposed and used, the steering system used in the dual-axle vehicle of the present invention has a front steering system, a rear steering system, and a rear steering system. a pulse motor driving a control pulse for a hydraulic actuator in the control unit, the front steering of which is configured to steer the front wheel axle of the front wheel reservoir, and
The rear steering is configured to include a hydraulic actuator and a control valve for the actuator to steer a rear wheel axle for a rear wheel of the last axle, and the control unit includes a vehicle speed sensor, and a steering amount sensor disposed on the front steering wheel, and a predetermined turning pattern for subsequently steering the wheel axle in relation to the front steering wheel, and a vehicle speed sensor; The iE Lus motor is driven in response to a signal from the steering amount sensor, and the wheel axle is then placed in either a steered state or a fixed state in accordance with the turning/turn.
The control unit also includes a vehicle speed sensor and a steering amount sensor disposed on the front steering wheel, and in connection with the front steering wheel, the control unit includes a vehicle speed sensor and a steering amount sensor disposed on the front steering wheel, and in connection with the front steering wheel, a predetermined amount of the wheel axle is then steered. It has a built-in turning A' turn, and drives its Norse Motor according to the signals from its vehicle speed sensor and steering amount sensor.
The wheel axle is configured to change the steering state according to the turning pattern, the fixed state, and the fixed or steered state based on a predetermined amount of steering. Therefore, when a rear dual-axle vehicle turns at low speed, the rear wheels of the last axle are steered according to the signals from the vehicle rate sensor and the steering amount sensor according to a predetermined turning pattern, and the vehicle's The turning radius can be made smaller, and the tires of the vehicle are less likely to skid, especially when the rear axle is
The side slippage of the rear wheels is extremely small, which prevents significant wear on the tires and improves turning performance.Also, when the vehicle is running at high speed, the rear axle and rear wheels are in a fixed state. The driving stability is improved, and
When the vehicle is turned at high speeds, the tendency of the vehicle to oversteer is avoided, making the turn safer; and when the vehicle is turned at medium speeds, its front wheel axle If the steering angle of the front wheel axle is within a predetermined angle, then the wheel axle is placed in a fixed state, and if the steering angle of the front wheel axle exceeds the predetermined angle, the subsequent wheel axle is placed in a fixed state in relation to the front wheel axle. When the wheels are steered, the skidding of the tires is reduced, significant wear of the tires is prevented, and safe turning is possible. Since side slippage is extremely reduced, the distance between the rear and front axles and the last axle can be increased, and even when driving on rough roads, 1. Wheel slippage is prevented, the load is applied evenly to both axles, the design conditions for always maintaining an equal ground load are relaxed, and the control system that makes such steering possible is simplified. Steering control is stabilized and vehicle design becomes easier.

As mentioned above, from the specific examples of the present invention explained with reference to the drawings, various modifications and changes will be easily made by those who have ordinary knowledge in the technical field to which this invention pertains. Furthermore, the structure of this invention can be easily replaced with an embodiment essentially the same as this invention that satisfies essentially the same problems as that invention and achieves the same effects as this invention. Let's do it.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a specific example of a steering system used in a rear two-axle vehicle of the present invention applied to a rear two-axle bus, and FIG. 2 is a steering system shown in FIG. 1. FIG. 2 is a schematic diagram showing a control system of a hydraulic actuator in FIG. 10... Steering system used in rear two-axle type vehicle, 11... Front steering, 12.13...
- Knuckle, 14.15... Front wheel axle, 26... Rear steering, 27.28... Knuckle, 29° 30... Rear wheel axle, 36... Hydraulic actuator,
40... Control unit), 41... Vehicle speed sensor, 42... Steering amount sensor, 44... Control O/L/B, 45... A' Lux motor, 50...
... Rear two axes! path. To figure 1, figure 2 L'l I-j

Claims (2)

[Claims] (1) A front steering wheel located at the front of a rear two-axle type vehicle to steer the front wheel axle of the front wheel, and a hydraulic actuator and a control system for the hydraulic actuator located at the rear of the vehicle.
A rear steering wheel that is equipped with a valve and that steers the rear wheel axle for the rear wheel of the last axle, a sonocontrol motor that drives the valve, a vehicle speed sensor, and a steering wheel that is located on the front steering wheel. and a built-in predetermined number of turns for subsequently steering the wheel axle in connection with the front steering, and in response to signals from the vehicle speed sensor and the steering amount sensor. A control unit that drives a pulse motor and controls its control valve so that the wheel axle is then put into either a steered state or a fixed state according to its turning pattern. steering system. (2) A front steering located at the front of a rear two-axle type vehicle to steer the front wheel axle of the front wheel, and a hydraulic actuator and a control system for the hydraulic actuator located at the rear of the vehicle.
A rear steering wheel that is equipped with a valve and that steers the rear wheel axle for the rear wheel of the last axle, a pulse motor that moves the sonocontrol valve, a vehicle speed sensor, and a steering amount located on the front steering wheel. the pulse motor in response to signals from the vehicle speed sensor and the steering amount sensor; and then set the wheel axle in either a fixed or steered state based on a steering state according to the turning angle, a fixed state, and a predetermined steering amount, A steering system used in rear two-axle vehicles that includes a control unit that controls its control pulp.