JPH07217601A - Liquid pressure source device - Google Patents

Abstract

PURPOSE:To facilitate regulating operation of discharging pressure of a liquid pressure pump which is soaked in operating liquid. CONSTITUTION:A tank 1 for reserving operating liquid is provided, and an electrically driven motor 13 and a discharging liquid pressure pump 15 which is driven by the electrically driven motor 13 and discharges the operating liquid with its discharge quantity capable of being changed are provided by soaking them in operating liquid which is reserved in the tank 1. The main valve 31 of a pressure control valve which is operated to suppress discharging pressure to a set pressure level is provided in the liquid pressure pump 15, the main valve 31 is connected to a relief valve 26 which is provided in the tank 1, and a regulating screw 27 for setting discharging pressure of the liquid pressure pump 15 is provided outside of the tank 1 from the relief valve 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic pressure source device having an electric motor and a hydraulic pump driven by the electric motor for sucking and discharging a working liquid, provided by immersing it in a working liquid stored in a tank.

[0002]

2. Description of the Related Art Conventionally, as a hydraulic pressure source device of this type, there is one disclosed in Japanese Patent Laid-Open No. 4-357301. This one stores the working liquid in a tank with an opening at the top,
An electric motor and a hydraulic pump driven by the electric motor to suck and discharge the working liquid are provided in a tank so as to be immersed in the working liquid stored, and a discharge port for supplying the working liquid discharged by the hydraulic pump to the outside and an external device. An upper plate on which a manifold provided with a return port for returning the working liquid used in step 1 to the tank is fixed is placed on the opening of the tank to close the opening of the tank.

[0003]

However, as a hydraulic pump of a hydraulic pressure source device, for example, Japanese Utility Model Publication No. 55-161 is used.
As disclosed in Japanese Patent Publication No. 49, a swash plate as a discharge amount changing member, an operation piston for operating the discharge amount changing member, and a pressure control valve for operating the operation piston are provided, and the discharge pressure of the hydraulic pump is adjusted to a pressure. A hydraulic pump that can change the discharge amount, such as changing the discharge amount by operating the operating piston with the pressure control valve, is often used so as to suppress the set pressure determined according to the spring force of the pressure regulating spring of the control valve. There is. However, if such a hydraulic pump is installed in a state where it is immersed in the working liquid inside the tank together with the electric motor, in order to set the discharge pressure to a predetermined pressure, remove the upper plate and place a hand in the working liquid through the opening of the tank. Therefore, the pressure control valve of the hydraulic pump has to be operated, and there is a problem that the adjusting operation for setting the discharge pressure to a predetermined pressure is difficult.

The present invention solves such a problem and provides a hydraulic pressure source device capable of facilitating the adjusting operation of the discharge pressure of a hydraulic pump provided by being immersed in a working liquid. The purpose is to

[0005]

Therefore, according to the present invention, in claim 1, there is provided a tank for storing the working liquid, and an electric motor and a liquid which is driven by the electric motor to change the discharge amount of the working liquid. A pressure pump and a tank are provided so as to be immersed in the working liquid for storage.The hydraulic pump has a discharge amount changing member for changing the discharge amount, an operating piston for operating the discharging amount changing member, and an operating piston. In a hydraulic pressure source device equipped with a pressure control valve that operates so as to suppress the discharge pressure to a set pressure, the pressure control valve is a main valve provided in the body of the hydraulic pump, and the main valve is separated from the inside of the tank. And a pilot valve attached to the tank at the main valve, the main valve having a supply passage connected to the pump discharge passage to supply the working liquid, an output passage connected to the operation piston, and a discharge passage for the drain. Hydraulic pump The valve body is movably accommodated in the valve hole formed in the main body of the valve so that the output passage is selectively connected to the supply passage and the discharge passage. A pressing chamber that presses the body in the direction in which the output passage communicates with the supply passage and a spring chamber in which a spring that presses the valve body in the direction in which the output passage communicates with the discharge passage are installed are formed. A passage for guiding the working liquid from the valve through the throttle is provided, and a connecting portion for connecting the spring chamber to the outside is provided.The pilot valve is adjusted in the valve body by the turning operation of the adjusting screw. The valve body is pressed by the spring force of the pressure spring in a direction to close the inlet and outlet passages and is pressed by the pressure in the inlet passage in a direction to open the inlet and outlet passages. If the pressing force exceeds the spring force of the pressure regulating spring, the inlet and outlet Between configured as a relief valve which communicates, and a connecting portion of the spring chamber of the inlet passage and the main valve of the pilot valve are connected to one another through pipes, the pilot valve mounting location of the tank has a through hole communicating the tank and out,
The valve body of the pilot valve is attached to a mounting portion so that the operating end of the adjusting screw is exposed to the outside of the tank through the through hole and the through hole is closed inside the tank.

Further, in the second aspect, in addition to the configuration of the first aspect, the operating end of the adjusting screw of the pilot valve is made to project outward from the outer surface of the tank where the through hole opens.

Furthermore, in the third aspect, in addition to the structure of the first aspect, the operating end of the adjusting screw of the pilot valve is positioned inside the tank outer surface where the through hole opens.

Further, in the fourth aspect, in addition to the constitution of the first, second or third aspect, a pressure gauge for detecting the pump discharge pressure is installed outside the tank.

[0009]

According to the structure described in claim 1 of the present invention, when the discharge pressure is lower than the set pressure set by the adjusting screw, the pressure control valve is supplied to the spring chamber through the passage provided with the throttle. The working fluid that has flowed in is prevented from being discharged to the tank by the relief valve, so the valve body of the pressure control valve moves to the position where the output passage communicates with the discharge passage due to the spring force of the spring installed in the spring chamber. A discharge amount of the working liquid is discharged. And
When the discharge pressure reaches the pressure set by the adjusting screw, the working liquid in the spring chamber of the pressure control valve is discharged from the relief valve to the tank, so the valve body of the pressure control valve acts based on the differential pressure generated before and after the throttle. Moves the output passage to a position communicating with the supply passage against the spring force of the spring, supplies the working liquid in the supply passage to the operation piston from the output passage, and operates the discharge amount changing member to discharge the hydraulic pump. The discharge pressure is suppressed to the pressure set by the adjusting screw. This set pressure can be adjusted by rotating the adjusting screw of the pilot valve, and the operating end of the adjusting screw of the pilot valve is exposed outside the tank.
It is possible to perform the adjusting operation without removing the upper plate of the tank and putting the hand in the working liquid, and to easily adjust the discharge pressure of the hydraulic pump provided by being immersed in the working liquid.

According to the second aspect of the invention, in adjusting the discharge pressure of such a hydraulic pump, the operating end of the adjusting screw protruding outward from the outer surface of the tank is rotated from the outer side of the tank. You can do that.

According to the third aspect of the invention, the discharge pressure of the hydraulic pump is adjusted by rotating the operating end of the adjusting screw located inside the outer surface of the tank. You can

Further, according to the structure of claim 4,
Such a work of adjusting the discharge pressure of the hydraulic pump can be performed while monitoring the pump discharge pressure with a pressure gauge installed outside the tank.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, reference numeral 1 denotes a tank, which is formed into a rectangular parallelepiped box shape having an upper opening and is provided with a working liquid capable of being stored therein. L1 is the liquid level of the working liquid. 2 is L
Both ends are placed on the upper ends of the side plates 3A, 3B facing each other of the tank 1 by a plate member formed in a letter shape. Reference numeral 4 denotes an upper plate included in the tank 1, which is composed of an upper plate 4A and an upper plate (not shown) provided on the back of the upper plate 4A. The upper plate 4 is in front of the plate member 2 partitioned by the plate member 2 in the direction perpendicular to the plane of FIG. The opening is closed by the upper plate 4A, and the opening at the back of the plate member 2 is closed by an unillustrated upper plate. A packing 5 is provided between the upper surface of the plate member 2 and the upper plate 4. Reference numerals 6A and 6B denote receiving plates fixed to the inner surfaces of the side plates 3A and 3B of the tank 1 by welding, and vibration-proof rubbers 7A and 7B are attached to the upper surfaces thereof. Reference numeral 8 denotes a holding frame, which has a horizontal mounting portion 9 and suspension portions 10A and 10B standing upright at both ends of the mounting portion 9.
B has mounting pieces 11A and 11B fixed to the upper end thereof so as to project in a direction orthogonal to the paper surface. The holding frame 8 is provided with a vibration-proof rubber 7 at the protruding ends of the mounting pieces 11A and 11B.
The mounting portion 9 is placed in the working liquid stored in the tank 1 by being placed on the A and 7B and fixed by the mounting screws 12A and 12B.

Reference numeral 13 denotes an electric motor, which is mounted on the mounting portion 9 of the holding frame 8, fixed by mounting screws 14A and 14B, and immersed in the working liquid. Reference numeral 15 denotes a hydraulic pump which is driven by the electric motor 13 and discharges the working liquid in a changeable manner. The hydraulic pump 15 is a swash plate type variable displacement piston pump, which is connected to the electric motor 13 and immersed in the working liquid. Reference numeral 16 is an adjusting bolt for adjusting the maximum discharge amount of the hydraulic pump 15.
Reference numeral 17 denotes a suction pipe connected to the hydraulic pump 15, and a strainer 18 is provided at the tip. Reference numeral 19 is a discharge pipe formed by using a hose which is a flexible pipe and joints, and one end of which is a hydraulic pump 15
And the other end is connected to the lower part of the manifold 20 fixed to the upper plate 4, and the working liquid discharged from the hydraulic pump 15 is introduced into the manifold 20. The manifold 20 is provided in the tank 1 at a position above the liquid surface of the working liquid to be stored. Reference numeral 21 denotes a return pipe, which is provided so as to hang from the lower surface of the manifold 20 and whose tip is immersed in the working liquid for storage in the tank 1. Reference numeral 22 is a discharge port, and 23 is a return port, which are provided above the manifold 20 so as to be connected to an external hydraulic device (not shown). The manifold 20 has a discharge pipe 19 and a discharge port 2
2 and a return pipe 21 and a return port 23 are provided to communicate with each other. A drain pipe 24 is fixed to the side plate 3C of the tank 1 above the liquid level L1 of the working liquid, one end of which is immersed in the working liquid and the other end of which is connected to the hydraulic device. A pressure gauge 25 detects the discharge pressure of the hydraulic pump 15, and is provided on the upper surface of the manifold 20 outside the tank 1.

Reference numeral 26 is a relief valve serving as a pilot valve of the pressure control valve, which is fixedly mounted on the lower surface of the plate member 2, and a rod-shaped adjusting screw 27 is projected from the relief valve 26 to the outside of the tank 1 to rotate the adjusting screw 27. The discharge pressure of the hydraulic pump 15 is changeable by a dynamic operation. Reference numeral 28 denotes a tubular member externally fitted to the adjusting screw 27, and 29 denotes a nut member screwed to the adjusting screw 27. The nut member 29 is brought into contact with the tubular member 28 to rotate the adjusting screw 27. Block the adjustment screw 27
It is provided so as to fix the set pressure obtained by the turning operation. The adjusting screw 27 is provided so as to increase the set pressure by rotating the adjusting screw 27 to the right when the tank 1 is viewed from above in FIG. Reference numeral 30 is a hose that is a flexible pipe that connects the main valve 31 of the pressure control valve provided in the hydraulic pump 15 and the inlet port of the relief valve 26. 32A and 32B are drain pipes using a hose, and the drain pipe 32A has one end connected to the outlet port of the relief valve 26 and the other end connected to a T-shaped joint 33 provided in the hydraulic pump 15, and The drain pipe 32B has one end connected to the joint 33 and the other end connected to the inlet port 35 of the cooler 34 provided on the upper plate 4 of the tank 1, and the working liquid discharged from the outlet port of the relief valve 26. Is introduced into the cooler 34 together with the drain discharged from the hydraulic pump 15.
The cooler 34 is formed by bending an inner hollow straight pipe 36 into a U-shape over a number of layers and forming an inlet port 35 and an outlet port 37 at both ends of the pipe 36. Is equipped with a fan 39 that is driven by an electric motor 38 (see FIG. 2) and blows air toward the pipe. The pipe 36 is housed in the frame 40, and the fan 39 is fixed to the frame 40 so that the pipe 36 flows. The liquid is provided so as to be cooled by the air blown by the fan 39. Reference numeral 41 denotes a drain pipe, which is provided so as to hang down from the outlet port 37 of the cooler 34 and has its tip immersed in the working liquid stored in the tank 1. Reference numeral 42 is a partition plate, and 43 is a fuel filler port.

The hydraulic pump 15 will be described in detail with reference to FIGS. 3 and 4. Reference numeral 44 denotes a hollow housing main body, and an end cover 45 is fixed to one side surface thereof to form a main body 46. Reference numeral 47 denotes a main shaft rotatably supported inside the housing main body 44,
A cylinder block 49 is rotatably supported together via a spline portion 48 formed in the middle thereof. Fifty
Is a large number of pistons provided on the cylinder block 49 so as to be capable of reciprocating with a predetermined stroke.
Are installed respectively. 52 is the housing body 4
4, a swash plate serving as a discharge amount changing member that is swingably provided within a range of a constant inclination angle, and shoes 51 attached to the tip of the piston 50 are in contact with each other. Reference numeral 53 denotes a back surface of the swash plate on the side where the shoes 51 come into contact, and the housing body 4.
A spring interposed between the inner surface of the swash plate 4 and the inner surface of the slab 4 gives a spring force to maximize the inclination angle of the swash plate 52. Then, when the main shaft 47 is driven and the cylinder block 49 is rotated with the tilt angle of the swash plate 52 being maximized, the piston 50 reciprocates to obtain the maximum discharge amount, and the maximum discharge amount is the forward / backward movement of the adjusting bolt 17. Can be adjusted by changing the maximum tilt angle of the swash plate.

Reference numeral 54 is a guide member projecting from the end cover 45 into the housing main body 44, reference numeral 55 is an operation piston externally fitted to the guide member 54 so as to be slidable in the axial direction.
2 and the working chamber 56 is formed on the back side. Reference numeral 57 is a pump discharge passage, and 58 is a pump suction passage. The main valve 31 of the pressure control valve that supplies the working liquid to the working chamber 56 of the operation piston 55 is the end cover 4 that constitutes the main body 46.
5, a valve hole composed of a small diameter hole 59 and a large diameter hole 60 connected to the small diameter hole 59 is passed through. The small-diameter hole 59 has a supply passage 61 connected to the pump discharge passage 57 for supplying the working liquid, an output passage 62 connected to the working chamber 56 of the operating piston 55, and a discharge passage 63 for draining, which are axially spaced from each other. The plug member 64A closes the opening at one end. 65
Is a valve body axially movably fitted in the small diameter hole 59. A pressing chamber 66 communicating with the supply passage 61 is formed in the small diameter hole 59 at the end of the plug member 64 side, and the output passage 62 is formed by the axial movement. Is located between the opening of the supply path 61 and the opening of the output path 6
A switching land 67A positioned between the opening portion of No. 2 and the opening portion of the discharge passage 63 is formed in the intermediate portion, and the guide land 67B is provided at the end of the valve hole 59 that is continuous with the large diameter hole 60.
Is formed. The working liquid pressure in the pressing chamber 66 acts on the valve body 65 so as to press the output passage 62 in the direction of communicating with the supply passage 61. The valve body 6 in the large diameter hole 60.
5, the spring receiving member 68 abutting on the guide land 67B of 5,
The spring force is applied to the valve element 65 via the spring receiving member 68 and the output path 6
The spring chamber 69 is formed in the large-diameter hole 60 by accommodating the spring 68 that gives 2 to the discharge path 63. 64
B is a lid member for closing the large-diameter hole 60, and 70 is a nut member for fixing the lid member 64B screwed.

The pressing chamber 66 and the spring chamber 69 are provided with a throttle hole 71 provided in the valve body 65, a bottomed communication hole 72 opened at the end face of the guide land 67B, and a through hole 7 penetrating the spring receiving member 68.
3 are connected by a series of passages with a diaphragm (formed by the diaphragm hole 71) formed therebetween. Therefore, the working liquid from the supply passage 61, which is guided to the spring chamber 69 through the throttle hole 71, acts on the valve body 65 so as to press the output passage 62 in the spring chamber 69 in the direction communicating with the discharge passage 63. There is. 74
Is a connection portion provided with a screw portion on the outer opening side of the lid member 69,
The hose 30 is connected.

Referring to FIG. 5, the relief valve 26 will be described. Reference numeral 76 is a valve body, which is formed in a rectangular parallelepiped shape and has screws 77A,
It is fixed to the lower surface of the plate member 2 by 77B and provided inside the tank. The valve body 76 has an insertion hole 78 and a communication hole 78.
A valve hole 79 having a smaller diameter is continuously provided, and one end of each hole 78, 79 is opened. Reference numeral 80 denotes a spring receiver, which is a main body 81
And a head portion 82, the main body portion 81 is provided in the valve hole 79 so as to be vertically movable, the head portion 82 is provided in the insertion hole 78 so as to be vertically movable, and the head portion 82 of the insertion hole 78 is provided. Bottom 8
It is provided so as to come into contact with 3 and stop downward movement.
Reference numeral 84 denotes a lid member, which is provided so as to close one end opening of the insertion hole 78. The adjusting screw 27 contacts the spring receiver 80,
The lid member 84 is screwed into a female screw threaded to be projected to the outside of the tank, and has a tool engaging portion 27A at the projecting end which serves as an operating end for rotating operation. Reference numeral 85 is a poppet valve body, and valve hole 79
It is installed in the inside so that it can move up and down, and it moves downward to move the valve hole 7
It is provided so as to abut on a valve seat 86 formed in the lower part of 9. 87 is an inlet passage, which is provided on one end opening side of the valve hole 79,
Connection part 74 of main valve 31 and hose 30 provided for hydraulic pump
Are connected with. A first flow passage 88 is provided so that the working liquid in the inlet passage 87 flows into the valve hole 79. An outlet passage 89 is provided on the side surface of the valve body 76,
A is to be connected. Reference numeral 91 is a pressure adjusting spring, and the valve hole 7
9 is provided between the spring receiver 80 and the poppet valve body 85, and is provided so that the poppet valve body 85 is seated on the valve seat with a spring force corresponding to the movement of the adjusting screw 27 and the spring receiver 81 accompanying the rotation operation. ing. When the pressure of the working liquid flowing from the inlet passage 87 is smaller than the spring force of the pressure adjusting spring 91, the poppet valve body 85 sits on the valve seat 86 and prevents the working liquid from the inlet passage 87 from being discharged to the tank. However, when the pressure of the working liquid is larger than the spring force of the pressure adjusting spring 91, the working liquid is separated from the valve seat 86 and the working liquid in the inlet port passage is discharged to the outlet passage 89. Reference numeral 92 denotes an O-ring, which prevents the hydraulic fluid in the valve hole 79 from flowing out to the insertion hole 78. Then, the valve body 76 is provided with the adjusting screw 27 protruding from the through hole 93 penetrating the plate member 2 and the upper plate 4, and the through hole 9 is formed.
3 is attached to the plate member 2 so as to close the inside of the tank.

Next, the operation of this structure will be described. When the hydraulic pump 15 is driven by the electric motor 13, the working liquid stored in the tank 1 is sucked by the hydraulic pump 15 through the suction pipe 17, flows through the discharge port 22 through the discharge pipe 19, and is supplied to an external hydraulic device (not shown). The working liquid returned from this hydraulic device flows through the return pipe 21 through the return port 23 and flows back into the tank 1.

At this time, when the load on the hydraulic pump 15 increases, the discharge pressure rises, and the discharge pressure is adjusted by the adjusting screw 27.
When the set pressure set by is reached, the working liquid introduced into the spring chamber 69 after the throttle hole 71 flows through the pipe 30, flows through the cooler 34 from the relief valve 26, and is discharged to the tank 1. Therefore, the working liquid before the throttle hole 71 in the pressing chamber 66 that acts on the end surface of the valve body 65 on the right side of the switching land 23A and the working liquid after the throttle hole 71 that acts on the end surface of the guide land 67B in the spring chamber 69. To the pressure of 71
A differential pressure is generated by the throttling action of the valve body 65, and the valve body 65 moves leftward to a position where the output passage 62 is switched to the supply passage 61 and communicates against the spring force of the spring 68 by the acting force based on this differential pressure. The working liquid in the passage 61 flows through the output passage 62 and is supplied to the working chamber 56. For this reason, the operating piston 55 has the action chamber 56.
The spring 68 by the acting force based on the pressure of the working liquid supplied to
The inclination angle of the discharge amount changing member 52 is reduced against the spring force of the discharge amount, and the discharge amount is reduced. When the discharge pressure decreases due to the decrease in the discharge amount, discharge by the relief valve 26 is blocked, the liquid pressures of the pressure chamber 66 and the spring chamber 69 become the same pressure, and the spring 68
The spring force causes the valve body 65 to move to a position where the output passage 62 communicates with the discharge passage 63, and the liquid in the working chamber 56 of the operating piston 54 flows from the output passage 62 through the discharge passage 63 and is discharged to the low pressure side. The amount changing member 52 increases the inclination angle by the spring force of the spring 53, increases the discharge amount, and allows the discharge pressure to increase, whereby the discharge pressure of the hydraulic pump 15 is adjusted by the adjusting screw 27. The set pressure that is determined by the spring force of is not exceeded.

In order to increase the set pressure, after loosening the nut member 29, a tool such as a spanner is used for the tool engaging portion 27.
Engage with A and rotate the adjusting screw 27 to the right when viewed from above in FIG. By this operation, the spring force of the pressure regulating spring 91 provided in the relief valve 26 for seating the poppet valve body 85 on the valve seat 86 is increased. Therefore, the pressure of the working liquid in the spring hole 59 is increased and the discharge pressure is gradually increased. Since this discharge pressure is displayed on the pressure gauge 25, the pressure gauge 25
The rotation of the adjusting screw 27 is stopped when the discharge pressure reaches the pressure to be obtained, and the nut 29 is tightened again to complete the operation for increasing the set pressure.

On the contrary, in order to reduce the set pressure, the adjusting screw 27 is turned to the left as viewed from above in FIG. By this operation, the spring force for seating the poppet valve body 85 of the pressure regulating spring 91 of the relief valve 26 on the valve seat 86 is reduced, and the discharge pressure gradually decreases accordingly. Therefore, while reading the pressure gauge 25, the discharge pressure is reduced. The rotation of the adjusting screw 27 is stopped when the pressure reaches the pressure to be obtained.

With this operation, when the set pressure is changed and adjusted, the discharge pressure can be monitored by the pressure gauge 25.
The discharge pressure of the hydraulic pump can be adjusted correctly and quickly.

Further, since the adjustment operation can be performed without the work of removing the upper plate 4 as in the conventional case,
It does not take time and the adjustment operation becomes easy.

Then, the adjusting screw 27 of the relief valve 26
Since the tool engaging portion 27A projects from the through hole 93 to the outside of the tank 1, the tool is easily engaged and operated during the turning operation, and the through hole 93 is
Since the relief valve 26 is closed by the valve body 76, foreign matter such as dust is prevented from entering the tank 1 from the outside.

Further, since the hose, which is a flexible tube, is used for the pipe between the relief valve 26 and the main valve 31, the hose can be bent depending on the connection point, and bending work when using a steel pipe, for example, can be performed. Piping connections are easily made in the tank 1 which is unnecessary and limited. Since the relief valve 76, which serves as the pilot valve of the pressure control valve, is separated from the hydraulic pump 15,
The relief valve 26 and the hydraulic pump 15 may be provided with a single pipe. For example, in the case where the conventional 3-port type pressure control valve is separated from the pump body, two pipes are provided between the pressure control valve and the hydraulic pump. This requires a book pipe, and compared to this, the pipe is small and simple. Further, since the relief valve 26 is provided inside the tank 1, the device becomes smaller in size as compared with the case where the relief valve 26 is provided outside the tank 1, and liquid leakage occurs from the relief valve 26, for example, the connecting portion of the pump 30. However, since the leaked liquid is returned to the working liquid stored in the tank 1, the outside of the tank is not contaminated.

FIG. 5 shows another embodiment of the relief valve. The same members as those of the embodiment are designated by the same reference numerals, and different points will be described. An adjusting screw 27 for setting the discharge pressure is provided in the relief valve 26. Provided in the lid member 84 by being screwed into the lid member 84,
The adjusting screw 27 is formed with a tool engaging portion 27A formed of a hole through which a tool such as a hexagon wrench can be inserted, and the tool engaging portion 27A is arranged inside the tank outer surface opening of the through hole 93 of the tank. Then, it is exposed to the outside of the tank through the through hole 93.

In this case, since the turning operation of the adjusting screw is carried out by inserting the tool into the tool engaging portion 27A through the through hole 93, the degree of freedom of operation is slightly restricted as compared with the previous embodiment. A compact device can be obtained by reducing the number of protrusions protruding outside the tank 1. The through hole 93 may be closed by a lid 94 except when necessary, as shown by an imaginary line.

In one embodiment, the discharge amount changing member 52
Although the swash plate type variable displacement piston pump having the swash plate is shown, it goes without saying that a variable displacement vane pump having a cam ring as the discharge amount changing member may be used.

[0031]

As described above, in the hydraulic pressure source device according to the first aspect of the present invention, the discharge pressure of the hydraulic pump is adjusted by operating the adjusting screw of the pilot valve at the operating end exposed to the outside of the tank. Since it can be adjusted, the discharge pressure of the hydraulic pump can be adjusted without removing the upper plate, and the adjustment operation can be facilitated. Since the pilot valve that is separated from the main valve in the pressure control valve of the hydraulic pump is a relief valve, the piping between the hydraulic pump and the relief valve is reduced, and the piping work is facilitated. Since the through hole that exposes the operating end of the adjusting screw to the outside of the tank is closed from the inside of the tank by the valve body of the relief valve, foreign matter from the outside does not contaminate the working liquid in the tank. Since this pilot valve is provided in the tank, the device does not become large, and even if leakage occurs at the pilot valve piping connection,
The outside of the tank can be prevented from being contaminated by this.

Further, in the apparatus according to the second aspect, since the operating end of the pilot valve adjusting screw projects out of the tank,
In addition to facilitating the turning operation of the adjusting screw, in the device according to claim 3, since the operating end of the adjusting screw does not project outside the tank, a small device having a small number of protruding parts from the tank can be obtained. By providing the pressure gauge as in claim 4, the discharge pressure of the hydraulic pump can be adjusted while monitoring the discharge pressure with the pressure gauge, so that the desired discharge pressure can be obtained correctly and quickly.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a hydraulic pressure source device showing an embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram of a hydraulic pressure source device.

FIG. 3 is a vertical cross-sectional view of a swash plate type variable displacement piston pump as a variable displacement hydraulic pump applied to a hydraulic pressure source device.

FIG. 4 is an enlarged cross-sectional view taken along the line BB of FIG.

FIG. 5 is a vertical sectional view of a relief valve applied to a hydraulic pressure source device.

FIG. 6 is a longitudinal sectional view of a relief valve showing another embodiment.

[Explanation of symbols]

 1 tank 13 electric motor 15 hydraulic pump 25 pressure gauge 26 pilot valve 27 adjusting screw 27A operation end 30 piping 31 main valve 52 discharge amount changing member 55 operation piston 57 pump discharge passage 59, 60 valve hole 61 supply passage 62 output passage 63 discharge Road 65 Valve body 66 Pressing chamber 68 Spring 69 Spring chamber 71 Restrictor 74 Connection portion 91 Pressure adjusting spring 93 Through hole

Claims (4)

[Claims] 1. A tank provided with a working liquid is provided, and an electric motor and a hydraulic pump driven by the electric motor to change the discharge amount of the working liquid are provided in the tank by immersing the working liquid in the tank. The hydraulic pump includes a discharge amount changing member for changing the discharge amount, an operation piston for operating the discharge amount changing member, and a pressure control valve for operating the operation piston to keep the discharge pressure at a set pressure. In the hydraulic pressure source device, the pressure control valve is formed by a main valve provided in the main body of the hydraulic pump and a pilot valve which is separated from the main valve and is attached to the tank inside the tank. Is the output passage to the valve hole formed in the body of the hydraulic pump, which is connected to the supply passage for supplying the working liquid by connecting to the pump discharge passage, the output passage for connecting to the operating piston, and the discharge passage for the drain. To the supply path and discharge path The valve body is movably accommodated so as to pass therethrough, and at both ends of the valve body of the valve hole, a pressure chamber that presses the valve body in the direction in which the output passage communicates with the supply passage by the pressure of the working liquid introduced from the supply passage, and the output passage. And a spring chamber in which a spring that presses the valve element in a direction leading to the discharge passage are installed, and a passage for guiding the working liquid from the supply passage to the spring chamber through a throttle is provided, and the spring chamber is externally provided. The pilot valve is pressed in the valve body in the direction closing the inlet passage and the outlet passage by the spring force of the pressure adjusting spring adjusted by the turning operation of the adjusting screw. , Has a valve body that is pushed by the pressure in the inlet passage in a direction to open the inlet and outlet passages, and communicates between the inlet and the outlet passage when the valve body pressing force due to the pressure in the inlet passage becomes larger than the spring force of the pressure adjusting spring. Relief valve And a connecting portion of the spring chamber passage and the main valve are connected to one another through pipes, the pilot valve mounting location of the tank has a through hole communicating the tank and out,
A hydraulic pressure source device, wherein a valve body of a pilot valve is mounted at a mounting portion so that an operating end of an adjusting screw is exposed to the outside of a tank through a through hole and the through hole is closed inside the tank. 2. The operation end of the adjusting screw of the pilot valve is projected outward from the tank outer surface where the through hole opens.
The hydraulic pressure source device according to. 3. The hydraulic pressure source device according to claim 1, wherein the operating end of the adjusting screw of the pilot valve is located inside the tank outer surface where the through hole opens. 4. The hydraulic pressure source device according to claim 1, wherein a pressure gauge for detecting a pump discharge pressure is installed outside the tank.