JPH08247104A - Hydraulic control device - Google Patents

Abstract

(57) [Abstract] [Purpose] When a pilot type switching valve is used and the flow rate of oil sent to this pilot oil passage is controlled using an electromagnetic proportional pressure reducing valve, shipping adjustment is facilitated and the oil of the operating oil is used. Ensure reliable operation even if the temperature or type changes. [Constitution] Main valve 1 consisting of pilot type switching valve
Pilot oil passages 32 and 33 for driving the hydraulic cylinder 2 by switching 6 and switching the main valve 16
Is connected to the electromagnetic proportional pressure reducing valves 30 and 31, pressure sensors 37 and 38 are arranged in this pilot oil passage to detect the pilot pressure, and this pressure sensor and the electromagnetic proportional pressure reducing valve are connected to the controller 40 to control the hydraulic pressure. Cylinder 2
The pilot pressure is increased below the critical operating pressure of the hydraulic cylinder except when the hydraulic cylinder 2 is operating, and the pilot pressure is fed back during operation to control to the set control pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic controller for a hydraulic actuator for driving a working machine for agricultural machines such as combine harvesters and tractors and construction machines such as backhoes.

[0002]

2. Description of the Related Art Conventionally, in an agricultural machine such as a combine or a construction machine, an operation such as raising and lowering or turning of a working machine is performed by a hydraulic actuator such as a hydraulic cylinder, and an electromagnetic switching valve or A solenoid for performing a switching operation of these valves is connected to a controller so that the solenoid is operated by an input from a sensor or a lever operation.

[0003]

However, when the pilot type switching valve is used as the switching valve and the flow rate of the oil feeding to the pilot oil passage is controlled by the electromagnetic proportional pressure reducing valve, the main valve is switched. It is necessary to adjust the pilot hydraulic pressure (hereinafter, critical operating pressure) that can be adjusted before shipping, and this shipping adjustment is a very delicate adjustment, and the adjustment takes a long time. In addition, since the operating pressure varies depending on the oil temperature and type of hydraulic oil, an error occurs, and there is hysteresis, so the critical operating pressure is not stable, and the critical operating pressure may change during use, making operation uncertain. There was a chance

[0004]

In order to solve the above problems, the present invention is configured as follows. That is, the hydraulic actuator is driven by switching the main valve consisting of the pilot type switching valve, the pilot oil passage for switching the main valve is connected to the electromagnetic proportional pressure reducing valve, and the pressure sensor is arranged in this pilot oil passage to control the pilot pressure. In addition to detecting, this pressure sensor and the electromagnetic proportional pressure reducing valve are connected to a controller to control the hydraulic actuator, and when the hydraulic actuator is not operating, the pilot pressure is increased below the critical operating pressure of the hydraulic actuator. During operation, the pilot pressure was fed back to control the set control pressure.

[0005]

By using such means, the pilot pressure is constantly detected by the pressure sensor, and when the hydraulic actuator is a hydraulic cylinder, the main valve is switched below the critical operating pressure when the hydraulic cylinder is not expanded or contracted. As described above, when switching the electromagnetic proportional pressure reducing valve to expand and contract the hydraulic cylinder, apply a predetermined current value to the solenoid of the electromagnetic proportional pressure reducing valve in addition to the exciting current at the critical operating pressure to apply the pilot oil passage. The pilot pressure that allows the main valve to be reliably switched to is sent, and the main valve is switched to operate the hydraulic cylinder.

[0006]

An embodiment of the present invention will be described below with reference to the drawings. 1 is an overall side view of the combine, FIG. 2 is a hydraulic circuit diagram for operating a hydraulic cylinder, FIG. 3 is a control block diagram,
FIG. 4 is a control block diagram showing another embodiment of the present invention, and FIG. 5 is a diagram showing the relationship between the exciting current applied to the solenoid of the electromagnetic proportional pressure reducing valve and the pilot pressure.

Referring to FIG. 1, a case where the hydraulic control device of the present invention is applied to a combine lifting device will be described. The combine projects a mowing device C as a working machine in front of the machine body on the crawler type traveling device 20, and C
The threshing device D is arranged in the rear part, the sorting device G is arranged in the lower part of the threshing device D, the straw processing device is arranged in the rear part, the driver's seat H is arranged in the right side, and the engine E is arranged under the driver's seat H. Seat H
A grain tank 9 is provided in the rear part, and the grain after threshing and selection is stored in the grain tank 9. The grain can be discharged by an auger 3, and the auger 3 moves up and down by a hydraulic cylinder 11. be able to.

The reaping device C projects the swarding board 4 at the front end of the reaping frame 5 and erects the raising device 10 at the rear part thereof,
A scraping device, a conveying device, and a cutting blade 6 are arranged at the rear part thereof, and the height of the cutting device C is detected by a sensor 7,
The height is changed by operating the lift lever 1 provided in the driver's seat H or by expanding and contracting the hydraulic cylinder 2 via the controller 40 in response to a signal from the height sensor 7. The height sensor 7 is provided with a contact piece so as to be rotatable, and is composed of a non-contact type ultrasonic sensor or the like.

As shown in FIG. 2, an engine E has a hydraulic circuit configuration for expanding and contracting the hydraulic cylinders 2 and 11.
The hydraulic pumps P1 and P2 are driven by the power from
The hydraulic pump P1 is connected to a relief valve 14 and a throttle 15 that form a flow control circuit 13, and the relief valve 14
Main valve 1 consisting of pilot type switching valve on the secondary side of
6, a pilot type check valve 17, a check valve 21 constituting the speed control circuit 19, a throttle 2
It is connected to a hydraulic cylinder 2 that raises and lowers the harvesting device C via 2. Further, the throttle 15 constituting the flow rate control circuit 13 is connected to the hydraulic cylinder 11 for moving up and down the auger 3 via an electromagnetic switching valve 23, a pilot type check valve 24 and a throttle 25.

The hydraulic pump P2 can be supplied with pressure oil to other hydraulic actuators via the flow rate control circuits 26 and 27, and the flow rate control circuit 27 can be used.
Electromagnetic proportional pressure reducing valves 30 and 31 are connected to the throttle 29. Pilot oil passages 32 and 33 for switching the main valve 16 are connected to the secondary side of the electromagnetic proportional pressure reducing valves 30 and 31, and pressure sensors 37 and 38 are attached to the pilot oil passages 32 and 33, respectively. The pressure is detected. Further, a shuttle valve 34 is interposed between the A port oil passage on the secondary side of the main valve 16 and the oil passage connecting the B port oil passage and the pilot-type check valve 17, and this shuttle valve 34 The secondary side is a relief valve 3
5 is connected to the pilot oil passage 36 to increase the hydraulic pressure when the hydraulic cylinder 2 is extended.

Therefore, when the hydraulic pumps P1 and P2 are driven by the power of the engine E, the hydraulic oil in the transmission case is sucked, and the pressure oil from the hydraulic pump P1 and the relief valve 14 constituting the flow control circuit 13 and the throttle valve are throttled. When the pressure oil from the relief valve 14 is diverted by the pressure control valve 15, the pressure oil is sent to the hydraulic cylinder 2 via the main valve 16, the pilot type check valve 17 and the check valve 21 to be extended when the pressure oil is operated to rise by the control described later. . When the lowering operation is performed, the main valve 16 is switched, the check valve 17 is opened, the hydraulic oil in the hydraulic cylinder 2 is throttled by the variable throttle 22, and the flow rate is limited, so that the check valve 17 and the main valve 16 are opened. Through to the tank and the harvesting device C slowly descends.
In addition, by switching the electromagnetic switching valve 23 to the rising side,
The pressure oil from the throttle 15 is sent to the hydraulic cylinder 11 via the electromagnetic switching valve 23, the check valve 24, and the throttle 25 to extend the hydraulic cylinder 11, and when the lowering operation is performed, the pressure oil in the hydraulic cylinder 11 is reduced to the throttle 25 and the check valve 24. , Is drained to the tank via the electromagnetic switching valve 23, and the hydraulic cylinder 11 is contracted.

The solenoids 30a and 31a of the electromagnetic proportional pressure reducing valves 30 and 31 are connected to the controller 4 via an amplifier 41.
0 and is connected to the solenoid 23a.2 of the electromagnetic switching valve 23.
3b is also connected to the controller 40 via an amplifier, and the controller 40 is also connected to the height sensor 7, the rotation amount detection sensor of the lift lever 1, the rotation amount detection sensor of the lift / rotation lever of the auger 3, and the like. The controller 40 controls the hydraulic actuator.

The exciting current I to the solenoid of the electromagnetic proportional pressure reducing valves 30 and 31 and the electromagnetic proportional pressure reducing valves 30 and 31
As shown in FIG. 5, the pilot pressure P is proportional to the exciting current I and can be expressed as P = kI + d. The exciting current is passed through the electromagnetic proportional pressure reducing valve 30 (or 31) to generate the pilot pressure P. When P exceeds P0 (which is the critical operating pressure), the main valve 16 is switched and pressure oil flows from the primary side to the secondary side to allow the hydraulic cylinder 2 to expand and contract, and the pilot pressure is from P0 to Pmin. Since the operation is unstable, the range from Pmin to Pmax is used as the control region. However, when the electromagnetic proportional pressure reducing valve is manufactured and shipped, there is variation within an allowable range, and the critical operating pressure P0 changes even if the oil temperature or the like changes. For example, if the range from the characteristic a to the characteristic b is within the allowable range at the time of production, in the case of the characteristic a,
The electromagnetic proportional pressure reducing valve can be controlled when the exciting current I1 or less does not operate and the exciting current I3 flows. However, in the case of the characteristic b, the electromagnetic proportional pressure reducing valve may not be operated even if the exciting current I3 is passed.

Therefore, according to the present invention, even when the hydraulic cylinder is not operated, for example, at the time of idling, the electromagnetic proportional pressure reducing valves 30 and 31 are operated and the pilot pressures thereof are detected by the pressure sensors 37 and 38. Is controlled to always be P0 or less, and the characteristic is calculated. That is, k and d in the equation P = kI + d are constantly calculated so that when the hydraulic cylinder is moved up and down, an exciting current that ensures that the pilot pressure is within the range from Pmin to Pmax can be passed. .

Specifically, as shown in FIG. 3, the control signal from the controller 40 is converted into an analog signal by the D / A converter 42, and the analog signal is input to the amplifier 41. An exciting current is passed through 30 (or 31). This exciting current is fed back to the amplifier 41 so that it becomes the set current. That is, a predetermined exciting current (which can be calculated because it is proportional) which is a pilot pressure between Pmin and Pmax is supplied to the exciting current of the critical operating pressure P0. When the electromagnetic proportional pressure reducing valve 30 (or 31) is switched, hydraulic pressure flows in the pilot oil passage 32 (or 32), and the pilot pressure is detected by the pressure sensor 37 (or 38),
The pressure is fed back and controlled to a specified pressure, the main valve 16 is switched, and the pressure oil from the hydraulic pump P1 is sent to the hydraulic cylinder 2.

As another embodiment, as shown in FIG. 4, an exciting current is caused to flow from the controller 40 to the electromagnetic proportional pressure reducing valve 30 (or 31) by pulse width modulation (PWM) control. Can also feed back to the amplifier 41 and also feed back the pilot pressure to switch the main valve 16 with the proper pilot pressure to move the hydraulic cylinder 2 up and down. Although feedback control is shown in this embodiment, feedforward control, PID control, or fuzzy control may be used.

[0017]

Since the present invention is constructed as described above, the following effects can be obtained. That is, since the characteristics of the proportional pressure reducing valve are always calculated, the pilot oil pressure is adjusted so that the pilot pressure can operate the main valve even if the temperature of the hydraulic oil changes or deteriorates. It is possible to feed oil, prevent a response delay, etc., and reliably switch the main valve. In addition, even if there are variations in the characteristics of the proportional pressure reducing valve at the time of shipment or changes in the type of hydraulic oil (product number or grade), the characteristics are calculated, so there is no need to make strict adjustments before shipping. We were able to reduce the adjustment time at the time of shipment.

[Brief description of drawings]

FIG. 1 is an overall side view of a combine.

FIG. 2 is a hydraulic circuit diagram for operating a hydraulic cylinder.

FIG. 3 is a control block diagram.

FIG. 4 is a control block diagram showing another embodiment of the present invention.

FIG. 5 is a diagram showing a relationship between an exciting current applied to a solenoid of an electromagnetic proportional pressure reducing valve and a pilot pressure.

[Explanation of symbols]

 2 Hydraulic cylinder 7 Height sensor 16 Main valve 30/31 Electromagnetic proportional pressure reducing valve 32/33 Pilot oil passage 37/38 Pressure sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Taiji Mizukura 1-32, Chayamachi, Kita-ku, Osaka, Osaka Prefecture Yanmar Agricultural Machinery Co., Ltd. (72) Wataru Nakagawa 1-32, Chaya-machi, Kita-ku, Osaka, Osaka No. Yanmar Agricultural Machinery Co., Ltd. (72) Inventor Ritsuko Kajioka 1-32 Chayamachi, Kita-ku, Osaka City, Osaka Prefecture No. 32 Yanma Agricultural Machinery Co., Ltd. (72) Terumasa Inoue 1-32 Chaya-cho, Kita-ku, Osaka City, Osaka Prefecture No. Yanmar Agricultural Machinery Co., Ltd.

Claims (1)

[Claims] 1. A hydraulic actuator is driven by switching a main valve composed of a pilot type switching valve, a pilot oil passage for switching the main valve is connected to an electromagnetic proportional pressure reducing valve, and a pressure sensor is arranged in this pilot oil passage. In addition to detecting the pilot pressure, the pressure sensor and the electromagnetic proportional pressure reducing valve are connected to a controller to control the hydraulic actuator, and the pilot pressure is equal to or lower than the critical operating pressure of the hydraulic actuator except when the hydraulic actuator is operating. The hydraulic control device is characterized in that the pilot pressure is fed back to control the set control pressure during operation.