JPH05332301A - Structure of operating oil tank in oil pressure generating unit - Google Patents

Abstract

PURPOSE:To miniaturize and make compact an operating oil tank in an oil pressure generating unit by connecting a plunger pump and an operating oil tank to each other through an operating oil supply pipe, making the inside of a pump communicate with the tank through a return pipe, and setting up an air vent subtank so as to be higher than the operating oil tank on the return pipe. CONSTITUTION:A plunger pump 2 is reversibly rotated by a prime mover 25 to pressurize an operating oil to high pressure for derivering it through a discharge opening 16. In this case, the operating oil leaks through the small hole of a piston head and collects in a pump housing 10, and air in the operating oil is discharged, and collected with the leaked operating oil in an upper subtank 28 through an air return pipe 26, and a returning oil 27 is returned into an operating oil tank 3, and bubble-shaped air is discharged outside through an air vent pipe 29. Since the installing position of the operating oil tank 3 can be lowered by the above formation, a bonnet to cover the operating oil tank 3 can be formed low, and in the case of equipping a power working machine with the operating oil tank, an operater can improve his field of view for safely executing work.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic oil tank structure for a hydraulic pressure generating unit mounted on a power excavator or the like.

[0002]

2. Description of the Related Art Conventionally, as a power source for hydraulic equipment such as a hydraulic actuator, there is a hydraulic pressure generating unit b such as an axial plunger pump a as shown in FIG. And the pump body c of the axial plunger pump a
Has a structure in which a rotary cylinder block e and a plunger piston f are housed inside a pump housing d, and a hydraulic oil tank g and a pump main body c are connected by a hydraulic oil supply pipe h.

[0003]

However, in the above-mentioned conventional type, a part of the hydraulic oil leaks from the head portion of the plunger piston f provided inside the pump body c and collects in the pump housing d. It is necessary to return the leaked hydraulic oil to the hydraulic oil tank g side. Therefore, the pump housing d and the hydraulic oil tank g are connected by the return pipes j and k. However, in the pump housing d, not only the leaked hydraulic oil but also the air contained in the hydraulic oil needs to be discharged, so that the hydraulic oil tank g is provided above the pump body c position, and the return pipe j, It was necessary to return the leak hydraulic oil and air to the hydraulic oil tank g side via k.

Therefore, since the hydraulic oil tank is installed high, the height of the machine body is increased especially in a power work machine and the visibility from the driver side is deteriorated.

[0005]

Therefore, in the present invention, the plunger pump and the hydraulic oil tank are connected by a hydraulic oil supply pipe, and the inside of the plunger pump is communicated with the hydraulic oil tank by a return pipe. An operation in a hydraulic pressure generating unit characterized in that an air bleeding sub-tank is provided in the middle of the return pipe, and the height of the sub-tank is set at least higher than the oil surface position on the hydraulic oil tank side. It is intended to provide an oil tank structure.

[0006]

Embodiments of the present invention will be specifically described with reference to the drawings. In FIG. 1, reference numeral 1 is a hydraulic pressure generating unit, and the hydraulic pressure generating unit 1 includes a plunger pump 2 and a hydraulic oil tank 3.
It is composed of The plunger pump 2 and the hydraulic oil tank 3 are connected by a hydraulic oil supply pipe 4.

Reference numeral 5 is an input shaft provided inside the plunger pump 2, 6 is a rotary cylinder block that pivotally mounts a plunger piston 7 in a reciprocating manner, 8 is a piston head fitted to the tip of the plunger piston 7, and 9 is a swash plate. .. The plunger piston 7 and the rotary cylinder block 6 are integrally covered by a pump housing 10 and a pump lid 11 to form a plunger pump body 12. 13 is a retainer that supports the piston head 8, 14 is a ball guide that supports the center of the retainer 13, 15 is a suction port for hydraulic oil, and 16 is a discharge port for hydraulic oil.

Further, 17 is a ball bearing that supports the left side of the input shaft 5, 18 is a lower support pin that supports the lower side surface of the swash plate 9, and 19
Is an upper side support member that supports the upper side of the swash plate 9, and supports the swash plate 9 in an inclined state via a coil spring 20 and a spring float 21.

Reference numeral 22 is a coil spring that presses the rotary cylinder block 7 toward the swash plate 9, and reference numeral 23 is a gear pump that is connected to the rear portion of the pump body 12 and is linked to the input shaft 5 through a joint 24. A prime mover 25 transmits power to the input shaft 5.

Further, in FIG. 1, the plunger pump 2
The inside of the pump housing 10 and the hydraulic oil tank 3 are communicated with each other by a return pipe 26, and a sub tank 28 for venting air from the return oil 27 is provided in the middle of the return pipe 26. Moreover, the mounting height of the sub-tank 28 is set at least higher than the oil surface position of the hydraulic oil tank 3.

Reference numeral 29 is an air vent pipe, and an air cock may be provided at the tip of the air vent pipe 29. The return pipe 26 connected to the hydraulic oil tank 3 side from the sub-tank 28 is communicated with the upper part of the hydraulic oil tank 3 and is located above the oil level of the hydraulic oil 3A in the hydraulic oil tank 3. It is in communication.

A strainer 30 is provided at the base of the hydraulic oil supply pipe 4, and the strainer 30 is located inside the hydraulic oil tank 3. Reference numeral 31 is an opening / closing lid of the hydraulic oil tank 3.

FIG. 3 shows a second embodiment of the hydraulic pressure generating unit 1, in which 32 is a pump housing, and hydraulic oil is supplied between the pump housing 32 and the hydraulic oil tank 33. A hydraulic oil supply pipe 34 is provided, and a first return pipe 35, a second return pipe 36, and a sub tank 37 for bleeding air are provided. 38 is an air bleeding pipe,
Reference numeral 39 is a third return pipe that connects the sub tank 37 and the hydraulic oil tank 33.

A first return pipe 35 and a second return pipe 36 are connected between the pump housing 32 and the sub tank 37.

FIG. 4 is a side view of a backhoe on which the hydraulic pressure generating unit 1 is mounted. In the figure, reference numeral 40 is a swing frame, on which the prime mover 25, the hydraulic pressure generating unit 1, and the hydraulic oil tank 3 are mounted. It is equipped with. 41 is an excavation work unit, 42 is a crawler type traveling device, 43 is a driving operation unit,
44 is a driver's seat, and 45 is a hood that covers the prime mover 25 and the hydraulic oil tank 3.

The embodiment of the present invention is configured as described above, and when the prime mover 25 is started and the plunger pump 2 is rotated, the plunger piston 7 reciprocates with respect to the rotary cylinder block 6 and the hydraulic oil. Is pressurized to a high pressure and discharged from the discharge port 16. In this case, the piston head 8
Hydraulic oil leaks through a small hole 8A provided in the pump housing 10
The air contained in the hydraulic oil is discharged while being accumulated inside.

Therefore, the leaked hydraulic oil and air stored in the rotary cylinder block 6 are stored in the upper sub-tank 28 via the return pipe 26, and the return oil 27 is returned to the hydraulic oil tank 3 and bubbles. The air is discharged to the outside through the air vent pipe 29.

As described above, according to the above-described embodiment, the plunger pump 2 having the rotary cylinder block 6 and the plunger piston 7 and the hydraulic oil tank 3 are connected by the hydraulic oil supply pipe 4, and the rotary cylinder is used. Block 6
And pump housing with plunger piston 7
The inside of 10 and the hydraulic oil tank 3 are connected by a return pipe 26,
Moreover, since the hydraulic oil tank structure of the hydraulic pressure generating unit is provided with the sub-tank 28 for bleeding air in the middle of the return pipe 26 at a position higher than the oil level of the hydraulic oil tank 3, the air in the return oil is Since it is more directly discharged to the outside, and therefore the mounting position of the hydraulic oil tank 3 can be lowered, the bonnet covering the hydraulic oil tank 3 and the like is configured low, for example, when equipped on a power work machine such as a backhoe. The operator has good visibility and can perform work safely.

Further, the entire machine body is made compact and the turning performance of the machine body is improved.

FIGS. 6 and 7 show another embodiment relating to a power working machine such as a backhoe, which is a schematic view of a swing frame of a backhoe for excavation.

In the figure, reference numeral 50 denotes a backhoe turning frame,
It is rotatably mounted on a crawler type traveling device 51.
52 is a step surface formed in a step shape 53 on one side of the revolving frame 50. The step surface 52 is formed within the range of the turning radius R of the turning frame 50. 54 is a bracket for mounting the excavation boom.

Therefore, according to the above embodiment, it is safe because the driver can step up and down the step surface 52 formed in the stepped shape 53 when getting on or off the aircraft.

The inside of the lower side of the step surface 52 can be used as an intake passage of an engine or a tool box.

8 and 9 show another embodiment relating to a power working machine such as a backhoe.
Reference numeral 60 is an operation panel provided on a backhoe body 61, 62 is a driver's seat, and a joystick lever 63 and a lock lever 64 are provided in the front portion. The lock lever 64 is capable of blocking the driver's up-and-down passage 65.

66 is O when the lock lever 64 rotates up and down.
This is a lock lever switch that operates N / OFF. The lock lever switch 66 cuts off the solenoid valve 67 to cut off the hydraulic circuit on the working unit side when the lock lever 64 pivots downward and is cut off. To do.

Reference numeral 68 is a seat sensor provided below the driver's seat 62. When the driver is not seated in the seat 62, the solenoid valve 67 is turned off to turn on the hydraulic circuit on the working unit side. It shuts off. A controller 69 is connected to the lock lever switch 66 and the seat sensor 68, and the controller 69 is connected to the solenoid valve 67. The lock lever switch 66, the seat sensor 68, the controller 69 and the like constitute a safety device 70.

In the above embodiment, when the driver is not seated in the seat 62, the hydraulic circuit on the operating portion side is automatically shut off even if the lock lever 64 is not rotated downward. Therefore, even if the joystick lever 63 is touched unexpectedly, the working unit does not malfunction.

Therefore, in the past, especially in the case of a backhoe or the like, the working portion was a heavy object, and therefore it was dangerous to malfunction, but this malfunction can be reliably prevented.

[0029]

According to the present invention, a plunger pump,
The hydraulic oil tank is connected to the hydraulic oil supply pipe, the inside of the plunger pump and the hydraulic oil tank are connected by a return pipe, and an air bleeding sub-tank is provided in the middle of the return pipe to generate hydraulic pressure. Due to the hydraulic oil tank structure in the unit, the air in the return oil is directly discharged to the outside from the sub tank, and therefore the mounting position of the hydraulic oil tank can be lowered. As a result, the bonnet covering the hydraulic oil tank and the like is made low, and when equipped on a power work machine such as a backhoe, the operator's visibility is good and the work can be performed safely.

Further, the entire machine body is made compact and the turning performance of the machine body is improved.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional side view showing an outline of a hydraulic pressure generation unit according to the present invention.

FIG. 2 is a sectional side view of a plunger pump.

FIG. 3 is a partial cross-sectional side view showing a second embodiment of the hydraulic pressure generating unit according to the present invention.

FIG. 4 is an external view of a power working machine equipped with a hydraulic pressure generating unit according to the present invention.

FIG. 5 is a partial cross-sectional side view showing the outline of a conventional hydraulic pressure generation unit.

FIG. 6 is a schematic plan view showing a swing frame portion of the power working machine.

FIG. 7 is a schematic front view of the same.

FIG. 8 is a side view showing an operating portion of the power working machine.

FIG. 9 is an electric circuit diagram of the safety device.

[Explanation of symbols]

 2 Plunger pump 3 Hydraulic oil tank 4 Hydraulic oil supply pipe 26 Return pipe 28 Sub tank

Claims (1)

[Claims] 1. A plunger pump (2) and a hydraulic oil tank
Connect (3) to the hydraulic oil supply pipe (4), and connect the inside of the plunger pump (2) and the hydraulic oil tank (3) to the return pipe.
(26) communicate with each other, and an air bleeding sub tank (28) is provided in the middle of the return pipe (26), and the sub tank (28)
The hydraulic oil tank structure in the hydraulic pressure generating unit is characterized in that the height of the hydraulic oil tank is set at least higher than the oil level position on the hydraulic oil tank (3) side.