JPH05195560A - Hydraulic controller for backhoe - Google Patents

Abstract

PURPOSE:To prevent the de-stabilizing of the attitude of a backhoe device due to the change of the attitude of a boom at the attitude of the housing of the backhoe device by returning a main control valve to a neutral position and bringing a sub-control valve to the state of pressure-oil supply when a hydraulic cylinder reaches a section near a stroke end in the lifting-side operation of the boom. CONSTITUTION:When a housing switch SW is worked, a controller 12 supplies a main control valve V1 and a sub-control valve V2 with currents respectively, and a boom is elevated and operated at fixed speed. When the boom exceeds a specified position near to a stroke end, the controller 12 stops current supply to the sub-control valve V2, and a deceleration control means A gradually reduces supply currents to the main control valve V1 according to specified control characteristics, and decelerates and controls the lifting speed of the boom. When the boom reaches the stroke end, a hydraulic control means B stops current supply to the main control valve V1 while feeding the sub-control valve V2 with minimum currents in deceleration control for a fixed period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a main control valve for supplying and discharging pressure oil to a double-acting hydraulic cylinder for vertically swinging a boom in a backhoe device, and a pressure oil supply passage side for raising operation of the hydraulic cylinder. And a sub-control valve for controlling the supply of pressure oil only, and swinging the boom upward so that the position of the center of gravity of the backhoe device can be moved to the inside of the machine beyond the point vertically above the swing pivot of the boom. The present invention relates to a backhoe hydraulic control device in which a moving range is set.

[0002]

2. Description of the Related Art In the hydraulic control device for a backhoe described above, conventionally, both the main control valve and the sub control valve are set to be in a pressure oil supply state in accordance with a lever operation on only a boom raising operation side. It is configured so that a large amount of oil pressure can be obtained by confluently supplying pressure oil from two pumps when the load is increased due to the weight of the backhoe device itself and the weight of excavated soil, etc. During that time, the hydraulic control valve is always set to the pressure oil supply operation position, and the descending operation side oil chamber to which the pressure oil is not supplied is in communication with the hydraulic tank [for example, JP-A-3-63329 and JP-A-3-63329]. No. 2-289726].

[0003]

The backhoe is constructed so that the backhoe device can be stored inside the machine body rather than the outer end of the swivel base so that the maximum swivel diameter can be reduced. However, as described above, the center of gravity of the backhoe device is configured to be movable toward the inside of the aircraft with respect to the pivot of the boom. As a result, the boom cylinder receives a load in the direction extending from the downward load to the opposite side, a vacuum state appears inside the cylinder, and the backhoe device itself may fluctuate slightly back and forth, which makes the posture unstable. There was a flaw. The present invention aims to eliminate the above-mentioned problems.

[0004]

A characteristic configuration of the present invention is that in the hydraulic control device for a backhoe described at the beginning, when the hydraulic cylinder reaches the vicinity of a stroke end in the upward operation of the boom, the main control is performed. It is provided with hydraulic control means for controlling the valve to return to the neutral position and controlling the sub control valve to the pressure oil supply state.

[0005]

[Operation] The hydraulic cylinder reaches the stroke end,
When the center of gravity of the backhoe moves beyond the vertical upper point of the boom pivot to the inside of the aircraft, the main control valve is controlled to return to the neutral position, and the oil chambers on both sides for double-action are blocked by the control valves. In this state, pressure oil is supplied through the sub control valve in such a closed state. As a result, in the hydraulic cylinder, pressure oil is supplied to the ascending operation side oil chamber while the outlets of both sides of the hydraulic chamber are blocked, and the hydraulic piston is pressed to operate, so that the backhoe device can be prevented from fluctuating. The pressure oil from the sub control valve is drained to the tank via the relief valve.

[0006]

Therefore, although the turning radius can be suppressed to a small value, the sub-control valve for increasing the speed of the boom raising operation is effectively used, and the change in the attitude of the boom is caused in the retracted attitude of the backhoe. It has become possible to prevent the posture of the backhoe device from becoming unstable.

[0007]

Embodiments will be described below with reference to the drawings. Figure 5
Shows the backhoe. This backhoe is equipped with a hydraulic motor M for turning on a traveling machine base 2 equipped with a crawler traveling device 1.
The swivel base 3 is mounted on the swivel base 3 so that the swivel base 3 can be freely swiveled around the axis of ordinate, and the backhoe device 4 is connected to the swivel base 3.
The travel base 2 is provided with a dozer device 5. The backhoe device 4 pivotally connects an arm 7 and a bucket 8 to a boom 6 that is pivotally supported on the swivel 3 about a horizontal axis so that the arm 6 and the bucket 8 are pivotally supported, and each of them is a boom cylinder 15, an arm cylinder 16, and a bucket. The cylinder 17 is driven and rocked to perform excavation work. Also, boom 6
Is divided into a base end portion 6a, an intermediate portion 6b, and a tip end portion 6c, which are pivotally connected to each other about a longitudinal axis, and a base end portion 6a and a tip end portion 6c are linked to each other by a link 9 parallel to the intermediate portion 6b. The bucket 8 is configured to be movable in the left-right direction while maintaining a parallel posture by pivotally connecting the intermediate portion 6b with the offset cylinder 18 and swinging the intermediate portion 6b.
Is stored on the swivel base 3 laterally offset with respect to the boom base end portion 6a, so that the swinging fulcrum of the boom 6 can be operated so that the maximum swing diameter can be reduced [see FIG. 6]. The ascending side swinging movement range of the boom 6 is set so that the center of gravity of the backhoe device 4 can move to the inside of the machine body beyond the vertically upper point.

The boom cylinder 15, the arm cylinder 16, and the bucket cylinder 1 as hydraulic actuators.
Each of the turning hydraulic motor M and the turning hydraulic motor M is configured to be controlled and operated by a pair of left and right operation levers 11 which are provided on a control unit 10 provided on the turning base 3 and which are capable of cross swing operation. More specifically, as shown in FIG. 1, each of the cylinders 1
5, 16 and 17 and the turning motor M are configured to control the hydraulic flow rate by the electromagnetic proportional flow rate control valve V, respectively, and the operation amount of each operation lever 11 in each operation direction is controlled by four potentiometers PM1 to PM4. The control device 12 is configured to detect and control the current supply amount to each electromagnetic proportional flow control valve V based on the detected manipulated variable. In the pressure oil supply circuit for the boom cylinder 15, as shown in FIG. 3, the main control valve V1 for supplying and discharging the reciprocating pressure oil from the first hydraulic pump 13 to the double-acting boom cylinder 15 and the boom 6 are used. And a sub-control valve V2 that joins and supplies the pressure oil from the second hydraulic pump 14 only to the pressure oil supply path on the ascending side, and when the boom cylinder 15 is operating on the ascending side, the first and second When the hydraulic oils of the hydraulic pumps 13 and 14 are jointly supplied, for example, when a large weight is applied such as lifting the excavated earth and sand in a posture in which the backhoe device 4 is projected to the outside of the machine, a large hydraulic pressure acts. It is configured as follows. The control device 12 controls the backhoe device 4 in accordance with the manual operation of the storage switch SW.
From the excavation posture that the
The storage is automatically controlled toward the storage posture on the swivel base 3. Boom base end portion 6a, intermediate portion 6b,
Each of the arm 7 and the bucket 8 is provided with potentiometers PM5 to PM8 for detecting a relative swing angle at pivotal fulcrums of the arm 7 and the outputs of the potentiometers PM5 to PM8 are input to the controller 12, and the storage switch is provided. SW
When is pressed and operated, the hydraulic cylinders 15 to 18 are automatically controlled so that the outputs of the attitude detecting potentiometers PM5 to PM8 become the values of the preset storage state. At this time, the bucket 8 is controlled so as to always maintain a horizontal posture. Then, in the automatic storage operation as described above, in the deceleration control means A for decelerating the operation speed of the boom cylinder 15 toward the stroke end, and in the upward operation of the boom 6, the boom cylinder 15 reaches the vicinity of the stroke end. And a hydraulic control means B for controlling the main control valve V1 to return to the neutral position and controlling the sub control valve V2 in a pressure oil supply state in a control program format. That is, the control device 12
Executes the control as follows. As shown in FIG. 2, when the storage switch SW is operated, the main control valve V1
Then, current is supplied to each of the sub control valve V2 to raise the boom 6 at a predetermined speed [steps 1 and 2]. When the boom 6 crosses a predetermined position near the stroke end,
As shown in FIG. 4, the current supply to the sub control valve V2 is stopped, and the supply current to the main control valve V1 is gradually reduced according to a preset control characteristic to control the boom ascending speed to be decelerated [step 3]. ~ 5]. When the stroke end is reached, the current supply to the main control valve V1 is stopped, and the minimum current in the deceleration control is applied to the sub control valve V2 until the operation of the driving lever of another hydraulic actuator, for example, the swing motor M is completed. Is supplied [steps 6 to 10]. Then, the above control is repeated until it is reset [step 11].

It should be noted that although reference numerals are given in the claims for facilitating the comparison with the drawings, the present invention is not limited to the configuration of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a control block diagram.

[Fig. 2] Control flowchart

[Fig.3] Boom cylinder drive hydraulic circuit diagram

[Fig. 4] Control characteristic diagram

FIG. 5: Side view of backhoe

FIG. 6 is a side view of the backhoe in the retracted posture.

[Explanation of symbols]

 4 Backhoe device 6 Boom 15 Hydraulic cylinder B Hydraulic control means V1 Main control valve V2 Sub control valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yutaro Morishita 64 Ishizukita-machi, Sakai City, Osaka Prefecture Kubota Sakai Factory Co., Ltd.

Claims (1)

[Claims] 1. A double-acting hydraulic cylinder (15) for vertically swinging a boom (6) of a backhoe device (4).
A main control valve (V1) that supplies and discharges pressure oil to and from the boom, and a sub-control valve (V2) that controls the supply of pressure oil only to the pressure oil supply passage side for raising the hydraulic cylinder (15). 6) The backhoe having a rising-side swing movement range of the boom (6) set so that the center of gravity of the backhoe device (4) can be moved to the inside of the machine body beyond a point vertically above the swinging pivot. Of the hydraulic cylinder (1) in the upward operation of the boom (6).
When 5) approaches the stroke end, a hydraulic control means (B) is provided for controlling the main control valve (V1) to return to the neutral position and controlling the sub control valve (V2) to the pressure oil supply state. Backhoe hydraulic control device.