JP2721088B2 - Backhoe hydraulic operation structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a construction in which hydraulic oil from a main hydraulic pump is supplied to a boom cylinder through a main control valve and an oil supply passage, and hydraulic oil from a sub hydraulic pump is supplied to the boom cylinder. A sub-control valve that joins a road; and a hydraulic operation structure of a backhoe in which each of the control valves is configured to be a hydraulic pilot operation type.

[0002]

2. Description of the Related Art In the above-mentioned hydraulic operating structure of a backhoe, conventionally, a configuration is adopted in which hydraulic oil from the sub-hydraulic pump is supplied only to a raising operation side oil supply passage of a boom cylinder via a sub-control valve, and a main control valve There has been a configuration in which the auxiliary control valve is operated in conjunction with the lifting operation to increase the operating force of the boom raising operation.

[0003]

The above-mentioned conventional structure has a problem that the backhoe apparatus itself excavates the earth and sand by a backhoe apparatus, scoops the earth and sand by a bucket, and loads it on a transport vehicle or the like. The weight of the oil and the load of the earth and sand add to it, so if the oil pressure is set to a large value in advance in consideration of such a load, the same oil pressure will be applied even when the boom is lowered. Since the lowering speed becomes too fast due to the operation and the operation becomes difficult, the pressure oil from the two pumps is combined and supplied only in the case of the ascending operation in which a large load is applied. However, this type of backhoe may be used to perform asphalt splitting work, soil crushing work, etc. In such a case, a pile body is attached instead of the bucket of the backhoe device, The above operation is performed by lowering the boom cylinder using
In the above-mentioned conventional structure, when the boom cylinder is lowered, only the pressure oil from one pump is supplied, so that the boom lowering speed becomes slow and the sufficient crushing function and the pressure reducing function cannot be exhibited. was there. In the case of the structure in which the hydraulic control valve is directly operated by the operation lever via the link mechanism, the hydraulic cylinder is quickly responded to the operation of the lever of the hydraulic cylinder, so that it is relatively easy to make a shocking descent in the above-described operation. However, when the hydraulic control valve is of a hydraulic pilot operation type, there is a disadvantage that it is difficult to perform a delicate operation because a response delay of the hydraulic cylinder with respect to the lever operation occurs. An object of the present invention is to eliminate the above disadvantages.

[0004]

According to a feature of the present invention, in the backhoe hydraulic operation structure described at the beginning, the first joint flow path is connected from the sub control valve in conjunction with the boom raising operation of the main control valve. And a second oil supply passage for lowering from the sub-control valve via a second joint passage in conjunction with the boom lowering operation of the main control valve. And pressurized oil from the sub-control valve to the second merging passage.
It is characterized in that a switching valve operable to switch between a state in which the pressure oil is supplied to the oil supply path and a state in which the pressure oil is discharged is provided.

[0005]

When performing an operation such as asphalt splitting, the boom is lowered by setting the switching valve to a state in which the pressure oil from the sub-control valve is supplied to the lowering second oil supply passage. And the hydraulic oil of the first hydraulic pump and the hydraulic oil of the second hydraulic pump are supplied to the boom cylinder in a merged state, so that the descent speed of the boom can be increased, and a sufficient impact function can be exerted. Splits can be made effectively. Also, when performing a normal excavation work such as earth and sand, by setting the switching valve to a pressure oil draining state, it is unnecessary to perform an operation only to lower the boom to a position close to the ground with no load. The boom can be prevented from descending quickly.

[0006]

Therefore, the lowering speed of the boom can be selectively used between a high speed state and a low speed state in accordance with the type of work, and the hydraulic pilot operation type having a relatively slow response to the lever operation is provided. In addition, it is possible to efficiently perform operations such as asphalt splitting, and at the time of ordinary earth and sand excavation work, prevent the boom descent speed from becoming too high unexpectedly and prevent the deterioration of maneuverability. Can be prevented.

[0007]

Embodiments will be described below with reference to the drawings. FIG.
Shows the backhoe. This backhoe mounts a swivel 3 that can be swiveled around a vertical axis by a swivel motor M3 on a traveling machine base 2 provided with left and right crawler traveling devices 1 and 1 driven by traveling motors M1 and M2,
A steering unit 4 and a driving unit 5 are provided on the swivel base 3, and a backhoe device 7 is connected to an end of the swivel base 3 via a swing bracket 6 that can be driven and swung by a swing cylinder CY <b> 1 so as to be swingably stored. Dozer cylinder C in front of machine base 2
A dozer device 8 is provided so as to be able to vertically move and swing by Y2. The control section 4 is configured by mounting and supporting a driver's seat 10 on a driving section hood 9 and a control post 11 standing upright from the swivel 3 in front of the driver's seat 10.
The driver's seat 10 is configured to be slidable in the front-rear direction according to the physique of the driver, and the steering post 11 is also configured to be slidable in the front-back direction. That is, as shown in FIG. 2, a pair of front and rear spring ball type slide support portions 12 are provided on the lower surface side of the swivel table 3 on the left and right sides, and an engagement groove 13 is formed at a lower end portion of the steering post 11. 14 is supported by the slide support portion 12 so as to be slidable back and forth. The rail portion 14 is configured so as to form a deep groove concave portion at which the spring ball 12a is engaged and positioned at a predetermined interval, and position the rail portion 14. As shown in FIG. 3, the support 16 of the sunshade 15 that covers the control section 4 is configured so that the grease gun 17 is internally supported by the elastic support 18 and is closed by the lid 19. The backhoe device 7 is configured such that the boom 20, the arm 21, and the bucket 22 are pivotally connected to each other, and each of them is swingably driven by a boom cylinder CY3, an arm cylinder CY4, and a bucket cylinder CY5 to perform excavation work. As shown in FIG. 4, the tip of the bucket 22 where the excavation claw 23 is formed is formed in an arc shape in a plan view so that the center claw 23 bites in first and a large excavation force is obtained. is there. Next, the hydraulic operating structure of the backhoe will be described. FIG. 1 shows a hydraulic circuit structure.
Hydraulic oil from the first hydraulic pump P1 (an example of a sub hydraulic pump) is supplied to the left traveling motor hydraulic control valve V1, the boom cylinder speed increasing auxiliary control valve V2, and the arm cylinder hydraulic control valve V3.
And the hydraulic oil from the second hydraulic pump P2 (an example of a main hydraulic pump) is supplied to the hydraulic control valve V for the right traveling motor.
4. The main control valve V5 for the boom cylinder, the hydraulic control valve V6 for the bucket, and the hydraulic oil of the third hydraulic pump P3 is supplied to the hydraulic control valve V7 for the swing motor, the hydraulic control valve V8 for the swing cylinder, and the hydraulic control for the dozer cylinder. A hydraulic circuit is configured to supply each of the valves V9, and each of the pumps P1, P2, P3
The control valves corresponding to the above are respectively configured as center bypass type multiple valves. Further, each of the speed increasing sub-control valve V2, the arm cylinder hydraulic control valve V3, the boom cylinder main control valve V5, the bucket hydraulic control valve V6, and the swing motor hydraulic control valve V7 of the boom cylinder CY3 is It is configured to be a pilot operated type, and is configured to be switched by a pair of left and right operation levers 24, 24 disposed above the steering post 11 via hydraulic pilot operation valves. Then, in conjunction with the boom raising operation of the main control valve V5, the first joint flow path Q
1 to join the pressurized oil to the first oil supply passage L1 for ascending, and in conjunction with the boom lowering operation of the main control valve V5, from the sub control valve V3 via the second merging passage Q2. A state in which pressure oil is joined to the second oil supply passage for lowering L2, and a state in which the pressure oil from the sub control valve V2 is supplied to the second oil supply passage for lowering L2 to the second joint passage Q2; An electromagnetic two-position switching valve 25 that can be operated to switch to a state in which oil is drained is interposed. The switching valve 25 is biased by a spring toward the hydraulic oil drainage side, and is driven to be excited based on the operation of an operation switch SW disposed on the control unit 4 to lower the hydraulic oil to a second pressure oil.
It is configured to switch to a state of supplying to the oil supply passage L2. Therefore, when the work such as asphalt splitting is performed, the state is switched to the supply state, and the sub control valve V2 and the main control valve are switched via the hydraulic pilot operation valve Vp based on the operation of the operation lever 24 for operating the boom. V5 is switched to the same operation direction, and the hydraulic oil of the first hydraulic pump P1 and the hydraulic oil of the second hydraulic pump P2 are combined and supplied to the boom cylinder CY3 in each of the raising and lowering operations of the boom 20, and the operating speed is increased. It can be set to a state.
If the switching valve 25 is set to the oil drain side, the boom 20
The two pumps are joined only at the time of the upward operation, and only the pressure oil of the second hydraulic pump 2 is supplied at the time of the downward operation.

[Alternative Embodiment 1] The switching valve 25 may be configured to switch by depressing a foot pedal that is biased back, instead of using an electromagnetic valve.

[Second Embodiment] As shown in FIG. 6, the switching valve 25 may be interposed in a center bypass passage L3 of the third hydraulic pump 3 as a sub-hydraulic pump. In this case, the switching valve 25 is connected to the operation lever 2.
It is necessary to cooperate so as to be switched only when the lowering operation of the boom 20 of No. 4 is performed.

[0010] In the claims, reference numerals are provided to facilitate comparison with the drawings, but the present invention is not limited to the configuration of the attached drawings by the entry.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram

FIG. 2 is a cross-sectional view of a control section post support section.

FIG. 3 is a sectional view of a column.

FIG. 4 is a perspective view of a bucket.

FIG. 5 is a side view of the backhoe.

FIG. 6 is a hydraulic circuit diagram of another embodiment.

[Explanation of symbols]

 25 Switching valve CY3 Boom cylinder L1 First oil supply path L2 Second oil supply path P2 Main hydraulic pump Q1 First merge flow path Q2 Second merge flow path V2 Secondary control valve V5 Main control valve

Claims (1)

(57) [Claims] 1. A hydraulic system for supplying hydraulic oil from a main hydraulic pump (P2) to a boom cylinder (CY3) through a main control valve (V5) and an oil supply passage, and hydraulic oil from a sub hydraulic pump. And a sub-control valve (V2) for causing the control valve (V2) to join the oil supply path, and the control valves (V2) and (V5)
Is a hydraulic operating structure of a backhoe, which is configured as a hydraulic pilot operation type, and interlocks with the boom raising operation of the main control valve (V5) from the sub control valve (V2) to the first junction flow path (Q1). Through the first oil supply passage (L1) for ascending, and the main control valve (V
5) In conjunction with the boom lowering operation of 5), the auxiliary control valve (V
2) through the second junction (Q2) through the second oil supply passage (L2) for lowering to join the pressure oil, and from the sub-control valve (V2) to the second junction (Q2). The hydraulic operating structure of the backhoe having a switching valve (25) operable to switch between a state in which the pressure oil is supplied to the second oil supply passage for lowering (L2) and a state in which the pressure oil is drained.