JPH0239425B2 - - Google Patents

Description

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

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

In such a rear dual axle type truck, running stability is improved, but when turning, the rear wheel attached to the last axle skids, causing significant wear on the rear tire. Axial type trucks tend to have a relatively large minimum turning radius compared to regular trucks.

In addition, in such a rear two-axis type truck,
If the rear wheel attached to the last axle is self-steering, the minimum turning radius of the truck can be reduced and significant wear on the rear tires can be prevented, but running stability at high speeds is impaired. . In other words, when the front wheels attached to the frontmost axle are steered by the front steering, they are not steered in proportion to the front steering angle, but in proportion to the magnitude of the lateral acceleration. There was a risk that the truck would oversteer.

The purpose and problem of this invention is to reduce the turning radius during low-speed driving, alleviate tire skidding, and prevent significant tire wear to improve turning performance. When driving, it improves driving stability, makes turning safer, and
To provide a steering system used in a rear two-axle type vehicle, which simplifies the steering control system and stabilizes the control.

In relation to the above-mentioned objects and problems, a steering system for use in a rear two-axle vehicle according to the present invention is arranged at the front of the rear two-axle vehicle, and includes a front wheel axle that rotatably supports the front wheels. a front steering wheel for steering, a hydraulic actuator and a control valve disposed at the rear of the vehicle, and for steering a rear wheel axle that is swingably connected to the rear axle and rotatably supports the rear wheels; A pulse motor drives the rear steering and its control valve, and when the vehicle is driven at low speeds, a pulse motor that steers the rear wheel axle in relation to its front wheel axle is used. When traveling at a high speed, if the front wheel axle is within a predetermined steering angle, then the wheel axle is fixed in a straight line, and if the front wheel axle exceeds the predetermined steering angle, then the It incorporates a predetermined turning pattern that steers the wheel axle relative to its front wheel axle and then locks the wheel axle in a straight line when the vehicle is traveling at high speeds. , the input side is electrically connected to the vehicle speed sensor and the steering amount sensor of the front steering wheel, and the output side is electrically connected to the pulse motor, and the signals from the vehicle speed sensor and the steering amount sensor are connected electrically to the steering amount sensor of the vehicle. A steering state in which a signal is output by matching the pattern, and the pulse motor is driven by the output signal to follow the turning pattern.
either fixed or steered based on a predetermined amount of steering, or a control unit that controls the control valve where the wheel axle is then placed in the fixed state. It is in.

An important convenience and benefit obtained by the steering system for use in a rear two-axle vehicle of the present invention so constructed is that its control unit is capable of transmitting signals from its vehicle speed sensor and steering amount sensor to its steering system. A signal is output in accordance with the turning pattern, and the output signal drives the pulse motor and causes the control valve to switch valves, so when the two-axle vehicle turns at low speed, the wheel axle The vehicle is steered in relation to its front wheel axle, the turning radius of the vehicle can be reduced, and the skidding of the tires is reduced, especially the skidding of the rear wheels of the last axle is extremely reduced, resulting in significant wear of the tires. is prevented, and the turning performance is improved, and when the vehicle turns at medium speed, if the front wheel axle is within a predetermined steering angle, the wheel axle is then fixed in a straight-ahead state, and when the front wheel axle exceeds the predetermined steering angle, the wheel axle is then steered in relation to the front wheel axle, reducing skidding of the tire and preventing significant wear of the tire; Safe turning is now possible, the turning performance is improved, and driving stability is improved accordingly.In particular, as the rear wheels skid during turning is extremely reduced, the rear and front axles are The distance between the axle and the last axle can be increased,
Even when driving on rough roads, the axle is prevented from slipping, the load is applied equally to both axles, the design conditions for equalizing the ground load are relaxed, and vehicle design is facilitated. When turning at high speed, the wheel axles are then fixed in a straight line, avoiding the tendency of the vehicle to oversteer, making the turning safer and thus improving driving stability. It is in.

From the above, it is certain that the present invention is useful as a steering device for rear two-axle type vehicles, such as heavy trucks, rough terrain trucks, large buses, etc.
Are suitable.

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

1 and 2 show front wheel axles 14, 15, rear front wheel axles 57, 58, and rear wheel axles 29, 30.
10 schematically shows a specific example 10 of the steering system of the present invention applied to a rear twin-axle bus 50 equipped with a rear twin-axle bus 50.

This steering system 10 includes a linkage type power steering device 21 and a bus 5 of the steering system 10.
A front steering wheel 11 is disposed in front of the vehicle 0 and steers front wheel axles 14 and 15 rotatably supporting front wheels 59 and 60 in accordance with the operation of a steering wheel 19, a hydraulic actuator 36, and a control. - equipped with a valve 44 and arranged at the rear of the bus 50, and
A rear wheel 65, which is swingably connected to the last axle 53,
66 rotatably supported by the rear wheel axle 29, 3
0, a pulse motor 45 that drives the control valve 44, and a rear wheel steering wheel connected to the front wheel axles 14, 15 when the bus 50 is running at low speed. When the bus 50, which steers the axles 29 and 30, is running at medium speed, the front wheel axle 1
When the front wheel axles 14, 15 are within a predetermined steering angle, the wheel axles 29, 30 are fixed straight ahead, and when the front wheel axles 14, 15 exceed the predetermined steering angle, the wheel axles 29, 30 are fixed straight ahead. 30 to its front wheel axle 1
4, 15, and
When the bus 50 travels at high speed, it incorporates a predetermined turning pattern (not shown) that fixes the wheel axles 29 and 30 in a straight-ahead state, and the vehicle speed sensor 41 of the bus 50 and The input side is electrically connected to the steering amount sensor 42 of the front steering 11, and the output side is electrically connected to the pulse motor 45, and the signals from the vehicle speed sensor 41 and the steering amount sensor 42 are applied to the turning pattern. A signal is output after comparison, and the pulse motor 45 is driven by the output signal, and the steering state follows the turning pattern, and the state is fixed or steered based on a predetermined steering amount. or the wheel axle 2 in a fixed state.
9 and 30, and a control unit 40 for controlling the control valve 44 thereof.

That is, in the rear two-axle bus 50, the rear front wheel axles 57, 58 supporting the wheels 61, 62, 63, 64 of the rear front axle 54 are connected to an engine (not shown) mounted at the rear of the bus 50. ), and the front wheel axles 14, 15 rotatably supporting the front wheels 59, 60 are steered by the power steering device 21 in accordance with the operation of the steering wheel 19, When the vehicle 50 travels at low speed, the rear wheel 65 of the last axle 53,
66 rotatably supported by the rear wheel axle 29, 3
0 is steered in relation to its front wheel axles 14, 15 obtained by comparing the turning pattern, and when the bus 50 travels at a medium speed, its front wheel axles 14, 15 are steered in relation to the predetermined position. If the steering angle is within the predetermined steering angle, then the wheel axles 29, 30 are fixed straight ahead, and if the front wheel axles 14, 15 exceed the predetermined steering angle, then the wheel axles 29, 30 are fixed straight ahead. 30 is steered in relation to its front wheel axles 14, 15 obtained by comparing the turning pattern, and furthermore, when the bus 50 travels at high speed, the wheel axles 29, 30 are then steered in a straight-ahead state. Manufactured where it is fixed.

The front steering 11 is connected to the front wheel axle 1
4, 15, and tie rod arm 16,
King pins 24 and 25 are provided at both ends of a front axle beam 52 located in front of the front frame 51 of the bus 50.
A pair of knuckles 12 and 13 rotatably attached to each other via a tie rod 1 that connects the ends of the tie rod arms 16 and 17 to each other.
8. A linkage type power steering device 21 equipped with a control valve, which controls the operating force of the steering wheel 19.
a coupling mechanism 22 connecting the steering shaft 20 and its control valve so as to transmit power to the valve; a coupling mechanism 22 that is integrally formed with the knuckle 13 so as to drive the knuckle 13; It is comprised of a link lever 23 connected to the operating rod end of the power cylinder 21, a hydraulic pressure supply source (not shown) for the power steering device 21, and the like.

The front steering wheel 11 is configured to be substantially the same as the steering wheel applied to existing buses.
The explanation of the component parts will be omitted.

Of course, the front wheels 5 are attached to the front wheel axles 14 and 15.
9 and 60 are attached respectively.

Therefore, by operating the steering wheel 19, the power steering device 21 rotates the knuckles 12, 13 in the same direction, the front wheel axles 14, 15 are steered, and the front wheels 59, 60 are steered. The angle can be changed.

Of course, the power steering device 21 is
Although the linkage type is described above, it is also possible to use an integral type or a semi-integral type.

Then the wheels 61, 62, 63, 6 of the front axle 54
The rear front wheel axles 57 and 58 supporting the bus 50 are disposed near the rear of the chassis frame 51 of the bus 50, and are driven by an engine (not shown) mounted on the bus 50. It is composed of

The rear steering wheel 26 is connected to the rear wheel axle 29,3.
0, and tie rod arms 31 and 32, respectively, and the chassis frame 5 of the bus 50.
1, that is, the rear front wheel axle 5 mentioned above.
King pins 34, 35 are installed at both ends of the rear axle beam 53, which is located behind 7, 58.
A pair of knuckles 27, 28 rotatably attached to each other via a tie rod 3 connecting the ends of the tie rod arms 31, 32 to each other.
3, a hydraulic actuator 36 for driving the tie rod 33, and a control valve 44 for the hydraulic actuator 36.

The actuator 36 is a hydraulic cylinder,
A cylinder 37, a fixed rod 38 fixed substantially orthogonally to one end of the cylinder 37, a piston (not shown) fitted in the cylinder bore of the cylinder 37 so as to be able to reciprocate, and one end of the rod 38. It is made up of an operating rod 39 which 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 has a pair of ports 67, 6 on its side near one end, respectively communicating with cylinder chambers (not shown) on either side of the piston.
It has 8.

The actuator 36 configured in this way is
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 includes a tandem center type pump port 69 with a spool and a pair of hydraulic ports 70 and 71, and is operated by a pulse motor 45 to be described later. The spool is configured to slide to switch the flow of pressure oil from its pump port 69 to its hydraulic ports 70, 71.

Therefore, the pump port 69 of the control valve 44 receives oil via the hydraulic piping 46.
The hydraulic ports 70, 71 are connected to a pump (not shown), and the actuator 36 is connected to a pair of ports 67, 71 via hydraulic piping 47, 48.
68 respectively. Of course, the oil pump is driven by the engine mounted on the bus 50.

The pulse motor 45 is of the linear type and slides the spool of its control valve 44 to switch the flow of pressure oil from its pump port 69 to its hydraulic ports 70, 71.
It is attached to the control valve 44. Of course, the pulse motor 45 may be of a rotary type instead of a linear type, as long as it slides the spool in response to a signal from a 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 one side, and in response to the movement of the spool, the actuator 36 is driven.
As a result, the above-mentioned knuckles 27 and 28 rotate in the same direction, and then the wheel axles 29 and 30 are steered,
The rear wheel 6 was then attached to the wheel axles 29, 30.
The rudder angles of 5 and 66 can be changed.

The control unit 40 controls the front wheel axles 14 and 1 within a predetermined steering angle when the bus 50 is running at a low speed and when the bus 50 is running at a medium speed.
The vehicle speed sensor 41 and Steering amount sensor 42
The input side is electrically connected to the vehicle speed sensor 41 and the steering amount sensor 42, and the output side is electrically connected to the pulse motor 45. , its vehicle speed sensor 41 and steering amount sensor 4
The signal from 2 is compared with the turning pattern and a signal is output, and the pulse motor 45 is driven by the output signal, and the steering state according to the turning pattern is fixed based on a predetermined steering amount. the control valve 44 to then place the wheel axles 29, 30 either in the steered or steered state or in the fixed state;
It was mainly assembled from input and output circuits, arithmetic circuits, memory circuits, control circuits, and power supply circuits.

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 is connected to a speed meter cable (not shown) of the bus 50. ,
Moreover, it is 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.
0 at a predetermined position, and is electrically connected to the input circuit of the control unit 48.

Of course, the steering amount sensor 42 is desirably one that has high resolution as a rotation sensor, consumes little power, and generates a reliable and large signal as an output. A semiconductor type is used.

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

Therefore, the control unit 40
When the bus 50 is running at low speed, the signals from the vehicle speed sensor 41 and the steering amount sensor 42 are compared with the turning pattern, and a signal is output, and the pulse motor 45 is driven by the output signal, and the turning pattern is adjusted. Therefore, the control valve 44 is then controlled to steer the wheel axles 29, 30 to follow the front wheel axles 14, 15, and when the bus 50 is running at medium speed, the front wheel axles 14, 15 is within a predetermined steering angle, the hydraulic actuator 3 then fixes the wheel axles 29 and 30 in a straight-ahead state.
The control valve 44 is controlled to lock the piston of the vehicle 6 at a substantially neutral position, and when the front wheel axles 14, 15 exceed a predetermined steering angle, the signals from the vehicle speed sensor 41 and the steering amount sensor 42 are controlled. A signal is output by comparing the signal with the turning pattern, and the output signal drives the pulse motor 45, and the wheel axles 29, 30 then follow the front wheel axles 14, 15 according to the turning pattern. Furthermore, when the bus 50 is traveling at high speed, the hydraulic actuator 36's piston is set to a position where the wheel axles 29 and 30 are fixed in a straight-line state, that is, the piston of the hydraulic actuator 36 is set to approximately neutral position. The control valve 44 is controlled to lock into position.

Of course, the control unit 40 stores the predetermined turning pattern based on the Atsukerman system in a memory circuit, and adjusts the running speed of the bus 50 based on the turning pattern.
The steering direction and steering angle of the rear wheel axles 29, 30 in the rear steering wheel 26 are determined according to the rotation speed, rotation direction, and rotation angle of the steering shaft 20 in the front steering wheel 11.

Next, to describe the running of the two-axle bus 50 to which the above-mentioned steering system 10 is applied, when the bus 50 is running, a signal from the vehicle speed sensor 41 is always input to the control unit 40. .

When the bus 50 is running at a low speed and the front wheel axles 14, 15 are steered by operating the steering wheel 19, the steering amount sensor 42 detects the rotational speed, rotational direction, etc. of the steering shaft 20. Then, the rotation angle is detected and an output signal is sent to its control unit 40.

The control unit 40 drives the pulse motor 45 and controls the control valve 44 according to the output signal based on the pre-stored turning pattern, and as a result,
The actuator 36 is driven, and the rear
The steering wheel 26 then steers the wheel axles 29, 30.

Now, when the front steering wheel 11 is steered to the left in order to turn the bus 50 to the left, the rear steering wheel 26 is turned to the right at a predetermined steering angle so as to reduce the turning radius. is steered by.

Therefore, the turning radius of the bus 50 when traveling at low speed becomes smaller, and the rear steering wheel 2
Significant wear on the rear wheels 65 and 66 on the 6 side is prevented,
Improves turning performance.

Further, when the bus 50 is traveling at a medium speed, if the front wheel axles 14 and 15 are steered at a relatively small steering angle, that is, within a predetermined steering angle, the rear steering wheel 26 will be used to control the rear wheels. The shafts 29 and 30 are fixed in a straight running state, in other words, are placed in a fixed state, ensuring running stability,
When the front wheel axles 14, 15 are steered at a relatively large steering angle, that is, beyond a predetermined steering angle, the rear steering wheel 26 then turns the front wheel axles 14, 15, tire wear is reduced, the turning radius is reduced, and turning performance is improved.

Further, when the bus 50 is traveling at high speed, the control unit 40 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 steering wheel 26 then holds the wheel axles 29, 30 in a fixed state.

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

As understood from the above, the steering system used in the rear two-axle vehicle of the present invention is arranged at the front of the rear two-axle vehicle and steers the front wheel axle that rotatably supports the front wheels. A rear steering wheel is provided with a front steering wheel, a hydraulic actuator, and a control valve, and is located at the rear of the vehicle, and is swingably connected to the rear axle to steer the rear wheel axle that rotatably supports the rear wheels. A pulse motor that drives the steering and its control valves in relation to its front wheel axle when the vehicle is being driven at low speeds and subsequently steers the wheel axles when the vehicle is being driven at medium speeds. When driving, when the front wheel axle is within a predetermined steering angle, the wheel axle is fixed straight ahead, and when the front wheel axle exceeds the predetermined steering angle, the wheel axle is fixed. a predetermined turning pattern in which the vehicle is steered relative to its front wheel axle, and which subsequently locks the wheel axle in a straight line when the vehicle is traveling at high speed; The input side is electrically connected to the vehicle speed sensor and the front steering steering amount sensor, and the output side is electrically connected to the pulse motor, and the signals from the vehicle speed sensor and the steering amount sensor are connected to the turning pattern. A steering state in which a signal is output after comparison, and the pulse motor is driven by the output signal to follow the turning pattern.
either fixed or steered based on a predetermined amount of steering, or a control unit that controls the control valve where the wheel axle is then placed in the fixed state. Therefore, in the steering system used in a two-axle vehicle according to the present invention, when the vehicle turns at low speed, the control unit uses the signals from the vehicle speed sensor and the steering amount sensor to By matching the pattern to obtain an output signal and driving the pulse motor with the output signal, the rear wheels of the last axle are steered in relation to the front wheels, thereby reducing the turning radius of the vehicle; The skidding of the tires of the vehicle is reduced, especially the skidding of the rear wheels of the last axle is extremely reduced, significant wear of the tires is prevented, turning performance is improved, and the vehicle is able to drive at medium speeds. If the steering angle of the front wheel axle is within a predetermined angle when turning at If so, the wheel axle is then steered in relation to its front wheel axle;
In other words, the rear wheels are steered in relation to the front wheels, which reduces tire skidding, prevents significant wear on the tires, enables safe turns, and improves turning performance and driving. Stability is improved and rear wheels skidding when turning is extremely reduced, allowing for a longer distance between the rear and front axles and the last axle.Even when driving on rough roads, the axles are prevented from slipping and the load is evenly distributed between both sides. The design conditions for ensuring that the ground load is uniformly applied to the shaft at all times have been relaxed, and the control system that enables such steering has been simplified and the control of that steering has been stabilized.
Vehicle design is facilitated, and furthermore, when the vehicle is running at high speed, its last axle and rear wheels are kept stationary, improving running stability, and when the vehicle is running at high speed and turning. The tendency of the vehicle to oversteer is avoided when
Turning becomes safer, and it is useful and practical for heavy trucks, rough terrain trucks, large buses, etc.

As mentioned above, from the specific examples of the present invention explained with reference to the drawings, those who have ordinary knowledge in the technical field to which this invention pertains will understand the following:
Various design modifications and changes can be easily made, and furthermore, the content of this invention is essential to the realization of the invention that accomplishes the task of the invention,
It is derived from the technical essence of the invention, which is the nature of the invention, and can be easily replaced by an embodiment that is objectively recognized as incorporating it.

[Brief explanation of drawings]

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, 1
2,13...Natsukuru, 14,15...Front wheel axle, 26...Rear steering, 27,28...
...Natsukuru, 29,30...Rear wheel axle, 36...
Hydraulic actuator, 40... Control unit, 41... Vehicle speed sensor, 42... Steering amount sensor, 44... Control valve, 45...
Pulse motor, 50... rear two-shaft bus.

Claims (1)

[Scope of Claims] 1. A front steering wheel disposed at the front of a rear two-axle type vehicle, which steers a front wheel axle that rotatably supports the front wheels, and a hydraulic actuator and a control valve. placed at the rear, and
a rear steering wheel that steers the rear wheel axle that is swingably connected to the last axle and rotatably supports the rear wheels; a pulse motor that drives the control valve; and a pulse motor that drives the control valve. When the vehicle is traveling at medium speed, if the front wheel axle is within a predetermined steering angle, then the wheel axle is steered in relation to the front wheel axle. is fixed in a straight line, and when the front wheel axle exceeds the predetermined steering angle, the wheel axle is then steered in relation to the front wheel axle, and the vehicle is driven at high speed. In this case, a predetermined turning pattern is built in that will then fix the wheel axle in a straight-line state, and the input side is input to the vehicle's vehicle speed sensor and its front steering steering amount sensor, and the output is output to its pulse motor. The two sides are electrically connected, and the signals from the vehicle speed sensor and steering amount sensor are compared with the turning pattern to output a signal, and the output signal is used to drive the pulse motor to follow the turning pattern. a control valve that controls the control valve to subsequently place the wheel axle in a fixed steering state, either fixed or steered relative to a predetermined amount of steering, or in a fixed state; Steering system used in rear two-axle vehicles, including units.