JP2005343245A - Fully hydraulic power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fully hydraulic power steering device to be applied to a civil engineering vehicle such as a wheel loader etc. capable of correcting the steering wheel position properly even if an excessive force is applied to a steering cylinder. <P>SOLUTION: The fully hydraulic power steering device is composed of an orbit roll 2, the steering cylinder 3, a hydraulic pump 4, a steering wheel angle sensor 5, a steering angle sensor 6, a solenoid valve 7, and a controller 8, and in particular, characterized by that the solenoid valve 7 is installed on the primary side of the orbit roll 2, which allows the working oil from the pump 4 to be fed to the steering cylinder 3 via the orbit roll 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an improvement in a fully hydraulic power steering device applied to an earthwork vehicle such as a wheel loader.

In general, in an earthwork vehicle such as a large wheel loader, an all-hydraulic power steering apparatus including a pilot (flow amplifier) control system is employed to reduce an operation force.
However, this type has a problem that the position of the handle, that is, the position of the knob provided on the handle changes due to a small amount of oil leakage due to the total hydraulic type, and it is very difficult to operate.
For this reason, this type of all-hydraulic power steering apparatus is known that includes a correction device for correcting the handle position (see Patent Documents 1 to 14).

Japanese Utility Model Publication No. 53-72344 Japanese Utility Model Publication No.59-140967 Japanese Utility Model Publication No. 60-102173 Japanese Patent Publication No. 4-24270 JP-A 61-205557 JP-A-10-100916 JP-A-10-119797 Japanese Patent Application Laid-Open No. 10-111983 Japanese Patent Laid-Open No. 10-111984 JP-A-10-181626 Japanese Patent Laid-Open No. 11-235982 JP 2000-168603 A JP 2003-11841 A JP 2003-327150 A

However, all of them attempt to correct the handle position by providing a solenoid valve between the orbit roll, which is the secondary side of the orbit roll, and the steer cylinder, and adjusting the hydraulic oil acting on the steer cylinder.
However, when a strong force is applied to the steering cylinder and its internal pressure increases, there is a problem that the stroke and movement of the steering cylinder become unstable and accurate correction cannot be performed.
In particular, in earthwork vehicles such as large wheel loaders, the so-called body refraction (articulate) type that refracts the vehicle body and turns the wheel is used, so that excessive force is easily applied to the steer cylinder. It was written.

  The present invention has been devised in view of the above-mentioned problems and has been devised to solve this problem. The problem is that the steering wheel position can be accurately corrected even if an excessive force is applied to the steering cylinder. The present invention provides a fully hydraulic power steering apparatus.

  The all-hydraulic power steering apparatus of the present invention basically supplies an orbit roll operated by a steering wheel, a steer cylinder for turning a wheel, and supplies hydraulic oil to the steer cylinder via the orbit roll. Hydraulic pump, a steering angle sensor for detecting the steering angle, a steering angle sensor for detecting the steering angle, and the hydraulic oil from the hydraulic pump is provided on the primary side of the orbit roll via the orbit roll. Thus, the present invention is characterized by comprising a solenoid valve that can be replenished to the steering cylinder, and a controller that controls the solenoid valve based on the steering angle from the steering angle sensor and the steering angle from the steering angle sensor.

When the orbit roll is operated by operating the handle, the hydraulic oil supplied from the hydraulic pump to the steer cylinder via the orbit roll is controlled. For this reason, the steering cylinder is actuated in response to the steering operation, and the wheels are turned.
When hydraulic oil leaks from the orbit roll to the steering cylinder, the steering angle of the wheel and the steering wheel angle shift.
At this time, the steering wheel angle is detected by the steering wheel angle sensor, the steering angle is detected by the steering angle sensor, and these signals are input to the controller. In the controller, a signal for converging these deviations to zero based on the steering wheel angle and the steering angle is output to the solenoid valve. For this reason, the solenoid valve is controlled so as to replenish hydraulic oil from the hydraulic pump by the amount of oil leakage to the steer cylinder via the orbit roll. Therefore, the steering wheel angle and the steering angle are properly maintained, and the steering wheel position is not shifted.
The solenoid is provided on the primary side of the orbit roll so that the hydraulic oil from the hydraulic pump is replenished to the steer cylinder, so even if excessive force acts on the store cylinder, the steer cylinder can be operated reliably. Handle position can be corrected accurately.

  It is preferable to provide a steering valve that is pilot-controlled by an orbit roll and to control the steering cylinder by using this steering valve. In this way, the steering operation can be performed with a much smaller operating force, and the operator's fatigue can be greatly reduced.

According to the present invention, the following excellent effects can be achieved.
(1) Consists of an orbit roll, a steer cylinder, a hydraulic pump, a handle angle sensor, a steer angle sensor, a solenoid valve, and a controller. Since the steering cylinder can be replenished via the roll, the steering wheel position can be accurately corrected even if an excessive force is applied to the steering cylinder.
(2) A solenoid valve is provided on the primary side of the orbit roll so that hydraulic oil from the hydraulic pump can be supplied to the steer cylinder via the orbit roll. It is reasonable and does not cause cost increases.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a hydraulic circuit diagram showing a basic structure of an all-hydraulic power steering apparatus of the present invention.

  The all-hydraulic power steering apparatus 1 is composed of an orbit roll 2, a steer cylinder 3, a hydraulic pump 4, a handle angle sensor 5, a steer angle sensor 6, a solenoid valve 7, and a controller 8, and includes a wheel loader and the like. Applies to earthworking vehicles.

  The earth-moving vehicle is not shown in the figure, but the front and rear vehicle bodies provided so as to be able to bend around the vertical axis, the front and rear wheels provided so as to be able to rotate around the horizontal axis on each vehicle body, and the left and right bodies that refract the front and rear vehicle bodies. A pair of steer cylinders 3 is provided, and a so-called vehicle body refraction (articulate) type is employed in which the steer cylinder 3 turns the vehicle body by bending the vehicle body.

The orbit roll 2 is operated by a handle 9. In this example, the orbit roll 2 includes a valve unit 10 and a metering unit 11 that are operated by the rotation of the handle 9. The handle 9 includes a knob for improving operability and a handle shaft connected to the valve unit 10. The valve unit 10 has a function of supplying an oil amount proportional to the amount of rotation of the handle 9 to the steer cylinder 3 and is a 7-port 3-position switching valve. Two ports on the secondary side are the metering unit 11. It is connected to the.
The orbit roll 2 includes ports T, P, P ′, A, and B. The port T is connected to the tank 12, and a check valve 13 is interposed between the port T and the port P. It is installed.

  The steer cylinder 3 is for turning the wheel. In this example, the steering cylinder 3 is a pair of left and right that turns the wheel by refracting the front and rear bodies, and includes a rod chamber and a tail chamber. It is a dynamic type. The rod chamber and tail chamber of each steer cylinder 3 are connected to ports A and B of the orbit roll 2 via check valves 14. The check valve 14 includes a throttle valve connected in parallel thereto.

  The hydraulic pump 4 is for supplying hydraulic oil to the steering cylinder 3 via the orbit roll 2. In this example, the hydraulic pump 4 is driven by a prime mover (engine), and the suction side is connected to the tank 12. In addition, the discharge side is connected to the port P and the port P ′ of the orbit roll 2, respectively. A relief valve 15 is interposed between the discharge side of the hydraulic pump 4 and the tank 12.

  The handle angle sensor 5 is for detecting the handle angle. In this example, the handle angle sensor 5 is provided in the vicinity of the handle shaft, detects the rotation angle (handle angle) from the neutral position, and outputs a signal corresponding to this. It is supposed to be output.

  The steer angle sensor 6 is for detecting the steer angle. In this example, the steer angle sensor 6 is provided in the vicinity of the piston rod of one of the steer cylinders 3 and moves from the neutral position (steer angle zero position) (steer angle). A signal corresponding to the detected angle is output.

  The solenoid valve 7 is provided on the primary side of the orbit roll 2 and can supply hydraulic oil from the hydraulic pump 4 to the steer cylinder 3 via the orbit roll 2. In this example, the 2-port 2-position electromagnetic disconnection is performed. A throttle valve 16 and a check valve 17 are provided between the discharge side of the hydraulic pump 4 and the port P ′ of the orbit roll 2 and are provided in series on the secondary side thereof. Contains.

  The controller 8 controls the solenoid valve 7 based on the steering wheel angle from the steering wheel angle sensor 5 and the steering angle from the steering angle sensor 6. In this example, the steering wheel angle and the tearing based on the signal from the steering wheel angle sensor 5 are controlled. The deviation from the steering angle based on the signal from the angle sensor 6 is calculated, and the solenoid valve 7 is controlled so that the deviation converges to zero.

Next, the operation will be described based on such a configuration.
When the operator operates the handle 9 to operate the orbit roll 2, the hydraulic fluid supplied from the hydraulic pump 4 to the steer cylinder 3 via the orbit roll 2 is controlled. For this reason, the steering cylinder 3 is actuated in response to the steering operation, and the wheels are turned by bending the front and rear vehicle bodies.
When hydraulic oil from the orbit roll 2 to the steer cylinder 3 leaks, the steer angle of the wheel and the handle angle of the handle 9 are shifted.
At this time, the steering wheel angle is detected by the steering wheel angle sensor 5, the steering angle is detected by the steering angle sensor 6, and these signals are input to the controller 8. In the controller 8, a signal for converging these deviations to zero based on the steering wheel angle and the steering angle is output to the solenoid valve 7. For this reason, the solenoid valve 7 is switched to the communication position, and the hydraulic oil from the hydraulic pump 4 leaks to the steer cylinder 3 through the solenoid valve 7 → the throttle valve 16 → the check valve 17 → the orbit roll 2. To be replenished. Therefore, the steering wheel angle and the steering angle are properly maintained, and the steering wheel position is not shifted.

  Since the solenoid valve 7 is provided on the primary side of the orbit roll 2 and hydraulic oil from the hydraulic pump 4 is supplied to the steer cylinder 3, the steer cylinder 3 can be securely connected even when excessive force is applied to the steer cylinder 3. The handle position can be accurately corrected.

Next, a second example of the present invention will be described with reference to FIG.
FIG. 2 is a hydraulic circuit diagram showing a specific structure of the all hydraulic power steering device of the present invention.
In the second example, a steering valve 18 that is pilot-controlled by the orbit roll 2 is provided, and the steering cylinder 3 is controlled by the steering valve 18, so that a so-called pilot (flow amplifier) control system is adopted. , A flow control valve 19 for diverting the hydraulic oil to the steering and cargo handling is provided.
The steering valve 18 includes a main steering valve 19, a flow control valve 20, an appropriate number of pressure control valves 21, a check valve 22 and a throttle valve 23, and ports P1, P2, PB, T, Pa, Pb, A and B are provided.

Two main pumps 24 are provided at the ports P1 and P2 of the steering valve 18, a valve for cargo handling (not shown) is provided at the port PB, and a port A of the orbit roll 2 is provided via the cushion valve 25 at the ports Pa and Pb. , B, the port T, the tank 12 and the ports A, B are connected to the rod chamber and the tail chamber of the steering cylinder 3 via a check valve 14 including a throttle valve, respectively.
Since such a system is a pilot control system, the steering operation can be performed with a smaller operating force, and the operator's fatigue can be greatly reduced.

In the above example, the steer cylinder 3 turns the wheel by refracting the vehicle body. However, the steer cylinder 3 is not limited to this, and may be one that turns the wheel directly like a normal vehicle, for example. good.
In the previous example, the steer cylinder 3 was two double-acting cylinders, but the present invention is not limited to this. For example, a single double-rod double-acting cylinder may be used.
In the second example, the steer valve 18 is provided with the flow control valve 19, but may be connected to a main pump dedicated to steer, for example, by omitting this.

1 is a hydraulic circuit diagram showing a basic structure of an all hydraulic power steering device of the present invention. 1 is a hydraulic circuit diagram showing a specific structure of an all hydraulic power steering device of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... All hydraulic power steering apparatus, 2 ... Orbit roll, 3 ... Steer cylinder, 4 ... Hydraulic pump, 5 ... Handle angle sensor, 6 ... Steer angle sensor, 7 ... Solenoid valve, 8 ... Controller, 9 ... Handle, 10 ... Valve unit, 11 ... Metering unit, 12 ... Tank, 13 ... Check valve, 14 ... Check valve, 15 ... Relief valve, 16 ... Throttle valve, 17 ... Check valve, 18 ... Steer valve, 19 ... Main Steer valve, 20 ... flow control valve, 21 ... pressure control valve, 22 ... check valve, 23 ... throttle valve, 24 ... main pump, 25 ... cushion valve.

Claims (2)

  An orbit roll operated by a handle, a steer cylinder for turning wheels, a hydraulic pump for supplying hydraulic oil to the steer cylinder via the orbit roll, and a handle angle sensor for detecting the handle angle A steering angle sensor for detecting the steering angle, a solenoid valve provided on the primary side of the orbit roll and capable of supplying hydraulic oil from the hydraulic pump to the steering cylinder via the orbit roll, and a steering angle sensor. An all-hydraulic power steering apparatus comprising a controller that controls a solenoid valve based on a steering angle and a steering angle from a steering angle sensor. 2. The all-hydraulic power steering apparatus according to claim 1, wherein a steering valve that is pilot-controlled by an orbit roll is provided, and the steering cylinder is controlled by the steering valve.

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