JPH0330218Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application The present invention relates to a power steering device for facilitating steering operations when a working machine is attached to the front or rear.

(b) Prior Art In the power steering system for agricultural tractors, the technology for adjusting the steering force according to the load applied to the steering wheel is known as described in Japanese Utility Model Application Publication No. 57-55669. .

(c) Problems to be solved by the invention When working with a front loader attached to the front of a tractor, the front loader and the objects carried in its bucket put a load on the front wheels, making it difficult to turn the handle. It is. Furthermore, if a heavy object such as a trencher is attached to the rear of the tractor, the front part will lift up, causing the problem that the handlebar operation will be too light. Therefore, if it is too heavy, you will get tired easily and will be late to avoid danger, and if it is too light, you will turn the steering wheel too much. In particular, when driving on the road with a working machine attached, the higher the speed, the more danger is likely to occur.

The present invention provides a hydraulic cylinder and a pressure sensor as a means for detecting the load applied to the front wheels, and enables longitudinal and horizontal control of the aircraft body using the hydraulic cylinder.

(d) Means for solving the problem The problems to be solved by this invention are as described above.
Next, means for solving the problem will be explained.

In agricultural tractors, front axle 2
A hydraulic cylinder 17 is interposed between 6 and this machine,
The pressure of the hydraulic cylinder 17 is detected by a pressure sensor 18.
The electromagnetic flow control valve 14 is detected by the controller 24 based on the signal from the pressure sensor 18.
a, 14b are opened and closed to control the steering force of the hydraulic cylinder 15 of the power steering mechanism according to the load applied to the front wheels, and a tilt sensor 23 is provided to detect the longitudinal tilting of the aircraft body, The hydraulic cylinder 17 is expanded and contracted in response to a signal from the sensor 23, and the aircraft is controlled horizontally in the longitudinal direction.

(e) Embodiment The purpose of the present invention is as described above, and the structure of the present invention will be explained based on the structure of the embodiment shown in the attached drawings.

Fig. 1 is a side view of the entire agricultural tractor equipped with a front loader, Fig. 2 is a side view of the power steering system, Fig. 3 is a plan view of the front axle, Fig. 4 is a front view, and Fig. 5 is a hydraulic circuit diagram.

Figure 1 shows a front loader A mounted as a front mounting device, in which the arm 3 and bucket 4 are rotated by hydraulic cylinders 6 and 7 by operating the operating lever 1 on the side of the handle 2. be. When the front loader A is attached to the front of an agricultural tractor in this way, when the bucket 4 scoops up dirt, etc., the load on the front wheels 5 increases, and the entire machine tilts forward.
The steering wheel becomes harder to turn and the center of gravity moves forward. Therefore, if you drive while lifting the vehicle, the steering wheel becomes difficult to turn, which can easily lead to a dangerous situation.

The power steering device of the present invention eliminates such problems and has a second configuration.
3 and 4, a hydraulic pump 10 is provided at the front end of the engine 8 inside the bonnet 9, and a hydraulic oil tank 11 is provided above the hydraulic pump 10, which is connected through an oil supply pipe 12. This hydraulic oil is converted into pressurized oil by a hydraulic pump 10 from a hydraulic oil tank 11 via an oil supply pipe 12, and the pressurized oil is sent from a high-pressure pipe 13 to a control valve 14 at the base of the handle 2.

The control valve 14 switches the oil supply to change the rotation of the handle 2 into extension or contraction of the hydraulic cylinder 15, and controls the front axle 26.
The weight when turning the handle 2 is kept constant regardless of the load applied to the handle 2.

A hydraulic cylinder 15 is fixedly mounted on the front axle bracket 19, and a knuckle arm 16 is pivotally connected to the tip of a piston rod 15a of the hydraulic cylinder 15 to rotate the wheel. Between the front axle bracket 19 and the center pin 20 is a hydraulic cylinder 17 that raises and lowers the front of the machine.
, and the front axle 26 is connected to the links 21 and 2.
It is supported like a pantograph at 1, 22, 22,
It can be rotated left and right around the center pin 20.

The center pin 20 is vertically slidable on the rail portion 19a of the front axle bracket 19. Therefore, when the hydraulic cylinder 17 is expanded or contracted, the front part of the machine moves up and down. The load applied to the front axle 26 is detected by a pressure sensor 18 provided on the rod portion of the hydraulic cylinder 17, and the hydraulic cylinder 15 is controlled by the controller 24 so that the steering wheel turns at a constant level.

Further, when the machine is tilted forward or backward by a tilt sensor 23 provided on the machine, a controller 24 operates a hydraulic cylinder 17 to control the machine to maintain it horizontally.

To explain these controls with reference to the hydraulic circuit diagram shown in FIG. 5, when a load is applied to the front wheels by a front loader or the like, an output is output from the pressure sensor 18 to the controller 24, and the controller 24 controls the electromagnetic flow control valves 14a, 14
(b), the force feedback is controlled by transmitting radio waves proportional to the load.

In other words, when a large load is applied to the front wheels, the steering wheel is controlled so that it becomes easier to turn the steering wheel, and when the load becomes smaller, the steering wheel becomes heavier.

On the other hand, the tilt sensor 23 installed in the machine detects the front and rear tilt, and if the machine is tilted forward, the controller 2
4, actuate the solenoid 25a of the switching valve 25 to extend the hydraulic cylinder 17, lift the front part of the tractor so that it is horizontal as a whole, and conversely tilt it backwards, actuate the solenoid 25b of the switching valve 25 to extend the hydraulic cylinder 17. The cylinder 17 is reduced to lower the front part of the tractor so that it becomes horizontal as a whole.

(F) Effect As described above, when a working machine such as a front loader is attached to the front or a working machine such as a trencher is attached to the rear, the load on the front axle increases or decreases, causing the load on the front axle to increase or decrease. Although it leans back,
At that time, the controller uses the outputs of the pressure sensor and tilt sensor to reduce the force feedback if the load is large and it is difficult to turn the steering wheel, making it easier to turn, or vice versa, if the rear wheel is heavy and the front wheel is under less load. In such cases, the control is performed so that the steering wheel can always be rotated with a constant force by increasing the force feedback so that the steering wheel does not turn too easily. Also, if a load is applied to the front part and the aircraft tilts forward, the hydraulic cylinder in the front axle will extend and the entire aircraft will become horizontal. Conversely, if the front part starts to rise, the hydraulic cylinder will contract and the aircraft will become horizontal. It is controlled by

(g) Effects Since the present invention is constructed as described above, it has the following effects.

First, the operator can always operate with a constant steering force even if the work equipment is attached to the front or rear and a load is applied to the front or rear.

Secondly, even if the machine is tilted forward or backward, the hydraulic cylinder can be operated to level it, so even if the machine is not able to rise sufficiently because it is tilted backwards, the front side will go down, causing the machine to rise and create a ridge when turning. There was no longer any need to destroy things like this.

Third, it has become possible to achieve stable driving while driving on the road with the work equipment attached.

[Brief explanation of the drawing]

Fig. 1 is a side view of the entire agricultural tractor equipped with a front loader, Fig. 2 is a side view of the power steering system, Fig. 3 is a plan view of the front axle, Fig. 4 is a front view, and Fig. 5 is a hydraulic circuit diagram. 14... Control valve, 15... Power steering hydraulic cylinder, 17... Horizontal control hydraulic cylinder, 18... Pressure sensor, 24...
…controller.

Claims (1)

[Scope of utility model registration request] In agricultural tractors, front axle 2
A hydraulic cylinder 17 is interposed between 6 and this machine,
The pressure of the hydraulic cylinder 17 is detected by a pressure sensor 18.
The electromagnetic flow control valve 14 is detected by the controller 24 based on the signal from the pressure sensor 18.
a, 14b are opened and closed to control the steering force of the hydraulic cylinder 15 of the power steering mechanism according to the load applied to the front wheels, and a tilt sensor 23 is provided to detect the longitudinal tilting of the aircraft body, A power steering device characterized in that the hydraulic cylinder 17 is expanded or contracted in response to a signal from a sensor 23 to control the aircraft longitudinally and horizontally.