JPH02218872A - Radial piston pump - Google Patents

Abstract

PURPOSE:To simplify the structure and achieve the miniaturization by reciprocally moving a plurality of plungers radially provided around an eccentric ring by the rotation of the eccentric ring, and moving the eccentric ring in the radial direction against an energizing member by an eccentricity regulating piston. CONSTITUTION:A variable capacity plunger pump 12 has an eccentric ring 32 mounted on a shaft 31 rotated by a motor 3 in such a manner as to be movable in the radial direction, and a plurality of plungers 33 radially provided around it are reciprocally moved by the rotation of the eccentric ring 32. Hence, a pressure oil sucked in a plunger chamber 79 through a check valve 36 is pressurized and then discharged through a check valve 35. The eccentric ring 32 is moved in the radial direction against a compression spring 34 by the movement of the eccentricity regulating piston 21 to regulate the eccentric amount of the eccentric ring 32, whereby the discharge can be varied. The eccentricity regulating piston 21 has the pressure receiving area set in such a manner that the piston is protruded during the pressure oil flowing into an oil chamber 22.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable displacement radial piston pump.

[Conventional technology and its problems]

Conventionally, variable discharge volume radial piston pumps (radial plunge medium pumps) have been used as high-pressure hydraulic pumps.
is often used.

In conventional radial piston pumps with variable discharge volume, multiple oil chambers are formed radially around the circumferential surface of a rotationally driven shaft, and the tip of a plunger that is inserted into each oil chamber and can reciprocate in the radial direction is attached to the casing. slides along the inner peripheral surface of
The casing is configured to be eccentrically moved relative to the shaft by a hydraulic cylinder.

However, in such conventional radial piston pumps, the oil chamber was provided in the shaft, so switching valves and check valves for switching the oil path were also built into the shaft, making the shaft structure complicated. It was not possible to increase the number of blocks (the number of oil chambers and plungers), and it was not possible to increase the rotation speed of the shaft to increase the flow rate.

Furthermore, since it is difficult to process the inner circumferential surface of the casing with high precision, there is a limit to its use as a high-pressure pump, and the pump as a whole has to be large in size to support and move the casing.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a variable displacement radial piston pump that is small and suitable for high pressure.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides an eccentric ring that is provided to rotate integrally with a rotationally driven shaft and to be movable in a radial direction with respect to the shaft, and an eccentric ring that is provided on the shaft. an eccentric adjustment piston that drives the eccentric ring to move in a radial direction eccentric to the shaft; a biasing member provided on the shaft that biases the eccentric ring in a direction opposite to the direction in which the eccentric adjustment piston is driven; A plurality of plungers are arranged radially in the radial direction at the axial position of the ring and are reciprocated by the rotation of the eccentric ring.

[For production]

The eccentric adjustment piston moves so as to protrude radially outward in accordance with the amount of pressure oil that has flowed into the oil chamber.

The eccentric ring is adjusted by the protruding movement of the eccentric adjustment piston.
Move in the direction that increases the amount of eccentricity with respect to the shaft.

The biasing member moves the eccentric ring in a direction where the amount of eccentricity decreases when the pressure oil in the oil chamber decreases, or assists in this movement.

The plunger is reciprocated by the rotation of the eccentric ring,
The amount of oil discharged from the eccentric ring is varied depending on the amount of eccentricity of the eccentric ring.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 is a hydraulic circuit diagram of the radial piston pump 1 according to the present invention.

In FIG. 5, the radial piston pump 1 includes a gear pump 11 for low pressure and a plunger pump 12 for high pressure, which are arranged coaxially with each other, an eccentric adjustment piston 21 for variably adjusting the discharge amount of the plunger pump 12, and an eccentric adjustment piston. 21, a shutoff valve 13 for supplying or shutting off pressure oil to the oil chamber 22, and a drain port for draining the pressure oil in the oil chamber 22)P
It is composed of an unload valve 14 for releasing the water to D, and the like.

The suction port 11a of the gear pump 11 is connected to the suction boat PI, and oil is sucked from an external oil tank.
b is connected to the suction port 12a of the plunger pump 12,
The discharge port 12b of the plunger pump 12 is an output boat PO.
It is connected to the.

In addition, the discharge port 12b of the plunger pump 12 and the oil chamber 22
The above-mentioned shutoff valve 13 is connected between the shutoff valve 13, the pilot flow path 13c of the shutoff valve 13 is connected to the discharge port 12b, and the drain boat PD connected to the oil chamber 22 and the oil tank is connected to the Unload valve 14 is connected, unload valve 1
The No. 4 pilot flow path 14c is connected to the discharge port 12b. Note that a throttle valve 15°1 for preventing chattering is provided on the high pressure side of the unload valve 14 and the pilot flow path 14c.
6 is provided.

When the motor 3 rotates, the gear pump 11 and plunger pump 12 rotate simultaneously, and pressure oil from the gear pump 11 is supplied to the plunger pump 12. The pressure oil discharged from the discharge port 12b of the plunger pump 12 is
) In addition to being sent to the outside from the PO, it also flows into the oil chamber 22 through the shutoff valve 13.

The discharge amount of the plunger pump 12 is determined by the amount of movement of the eccentric adjustment piston 21, which projects according to the amount of oil flowing into the oil chamber 22. When the pressure at the discharge port 12b becomes higher than a certain level, the pilot flow path 13C switches the shutoff valve 13 to block the flow of pressure oil from the discharge port 12b into the oil chamber 22.

When the pressure at the discharge port 12b further increases, the unload valve 14 is operated by the pilot flow path 14c, and the oil chamber 22
The pressure oil flows out from the drain boat PD through the unload valve 14, and the eccentric adjustment piston 21 contracts.

The displacement of the eccentric adjustment piston 21 causes the discharge amount of the plunger pump 12 to decrease.

FIG. 4 is a diagram schematically showing the structure of the radial piston pump 1.

In FIG. 4, the plunger pump 12 is connected to the motor 3.
A shaft 3I rotationally driven by a shaft 3I, an eccentric ring 32 provided to rotate integrally with the shaft 31 and movable in the radial direction with respect to the shaft 31, and an eccentric ring 32 provided radially in the radial direction at an axial position of the eccentric ring 32. A plurality of plungers 33, 33, .
The above-mentioned eccentric adjustment piston 21
drives the eccentric ring 32 to move eccentrically in the radial direction with respect to the shaft 31, and the compression spring 34 biases the eccentric ring 32 in a direction opposite to the direction in which the eccentric adjustment piston 21 is driven. Note that the eccentric adjustment piston 21 is connected to the discharge port 12.
The pressure receiving area of the eccentric ring 32 is determined so that it always protrudes while the pressure oil from b is flowing into the oil chamber 22, and the eccentric ring 32 maintains a slight eccentricity even when the eccentric adjustment piston 21 is most contracted. A small amount can be obtained from the discharge port 12b.

A mechanical seal device 51 including a compression spring 52, a balance piston 53, and the like is provided on the end surface 31c of the shaft 31 for supplying and discharging pressure oil to the oil chamber 22.

The shutoff valve 13 has a piston 42 that moves so as to close a valve seat 44 with a hard ball 43 when the biasing force of the compression spring 41 becomes greater.

Note that the biasing force of the compression spring 41 can be adjusted by an adjustment screw member 46, which will be described later.

The unload valve 14 includes a hard ball 61 that is normally biased by a compression spring 62 to close the valve seat 63, and a hard ball 61 that is pushed when the pressure in the pilot flow path 14c" becomes higher than a set value. It has a balance piston 64 that opens.

FIG. 1 is a cross-sectional front view of a radial piston pump 1 according to the present invention, FIG. 2 is a cross-sectional front view showing a part of the radial piston pump 1 shown in FIG. FIG. 2 is an exploded view of the main parts of the radial piston pump 1. FIG.

Note that FIG. 2 is a cross-sectional view of a position above the unload valve 14 shown in the lower right portion of FIG. 1 on the plane of the paper. That is, the cutoff valve 13 shown in FIG. 2 is provided above the plane of the drawing in FIG. 1 with respect to the unload valve I4 shown in FIG. Furthermore, in FIG. 3, the housing cap 70, housing 71, etc. of the radial piston pump l shown in FIG. 1 are omitted.

In these figures, the shaft 31 is connected to the housing 71
A ball bearing 72 and a bearing receiver are rotatably supported via a member 73 and a needle bearing 74 in a shaft hole 71a provided in the motor 3.
It is rotationally driven by a rotating shaft 3a. housing 71
An annular oil passage 75 communicating with the discharge port 12b of the plunger pump 12 is formed between the bearing member 73 and the bearing member 73.

The shaft 31 is provided with a plunger pump shaft portion 31a to which the eccentric ring 32 is attached, and the above-mentioned eccentric adjustment piston 21 and compression spring 34 are attached to the plunger pump shaft portion 31a with radial pressure. are placed facing in the opposite direction. The eccentric ring 32 has a sliding hole 32d into which the width across flats of the plunger pump shaft portion 31a is slidably fitted, a spring bearing portion 32e, and a piston bearing portion 32.
It is composed of an eccentric ring member 32a with an angle f, and a needle bearing 32b attached to the outer peripheral surface of the eccentric ring member 32a.

In the housing 71, holes 76 are formed for mounting a plunger in the radial direction at a plurality of locations equally divided in the circumferential direction, and a plunger block 77 is attached to each hole 76 for mounting a plunger in the radial direction.

In the plunger block 77, the plunger 33 described above is inserted into a cylindrical plunger chamber 79 connected to the check valves 35 and 36, and the plunger 33 is urged outward (in the axial direction of the shaft 31) by a compression spring 78. It is composed of

When pressure oil flows into the oil chamber 22 and the eccentric adjustment piston 21 moves, the eccentric ring 32 moves upward in FIG. 1 against the biasing force of the compression spring 34, and the amount of eccentricity of the eccentric ring 32 increases. Become. As the shaft 31 rotates in this state, each plunger 33 reciprocates, sucks pressure oil into the plunge chamber 79 via the check valve 36, and transfers pressure oil from the plunger chamber 79 via the check valve 35 to the discharge port. Pressure oil is discharged to 12b.

The shaft 31 is provided with a gear attachment portion 31b for attaching the gear pump 11, and an inner rotor 81 is attached to the gear attachment portion 31b so as to rotate together with the key 84. As the inner rotor 81 rotates, the inner rotor 82, which is slidably and rotatably attached to the housing cap 70, also rotates, thereby sucking in oil from the suction port 11a and discharging it from the discharge port 11b.

The shaft 31 is provided with an oil passage 85 that extends in the axial direction and communicates with the oil chamber 22, and is open to the end face 31c.
The above-mentioned mechanical seal device 51 is provided on this end surface 31c.

The mechanical seal device 51 performs a sealing action when the balance piston 53 comes into pressure contact with the end surface 31c. In the state where the balance piston 53 is in pressure contact with the end surface 31c, the balance piston 53
The pressure-receiving area of the end face on the right side of the figure is slightly larger than or almost equal to the pressure-receiving area of the inner circumferential face on the left side, and is caused by the biasing force of the compression spring 52 or the pushing force due to this and the pressure oil flowing into the piston chamber 54. The pressure contact force is generated by this.

Note that 80 is a thrust collar and 83 is a pump holding member.

The unload valve 14 includes a collar 65, a presser screw member 66, and a valve hole 7Oa formed in the housing cap 70.
and the above-mentioned hard ball 61, valve seat 63, balance piston 64
Normally, the hard ball 61 is biased by the compression spring 52 to close the valve seat 63, but if the pressure in the pilot flow path 14C becomes higher than the set pressure by the compression spring 52, The balance piston 64 moves to the right in the figure to release the hard ball 61 away from the valve seat 63.

In addition, by rotating the adjustment screw part 68 provided on the cap 67 screwed with the presser screw member 66, the hard ball 6
The strength with which 1 is pressed against the valve seat 63 is adjusted, thereby adjusting the set pressure for starting unloading.

In FIG. 2, the shutoff valve 13 is connected to the housing cap 7.
A presser screw member 45 is screwed into the valve hole 70b formed in the valve hole 70b, and the aforementioned compression spring 41 is inserted into the presser screw member 45.
, a piston 42, and a valve seat 44 are attached, and the biasing force of the compression spring 41 is adjusted by rotating the adjustment screw member 46, and the pressure at which the cutoff valve 13 operates is adjusted. 47 is a compression spring that biases the hard ball 43.

Next, the operation of the radial piston pump 1 configured as described above will be explained.

When the shaft 31 rotates due to the rotation of the motor 3,
The gear pump 11 supplies low pressure oil to the suction port 12a of the plunger pump 12. The plunger pump 12 pressurizes low pressure oil to a high pressure and discharges it from the discharge port 12b. Pressure oil discharged from the discharge port 12b flows through the oil passage 75 and the oil passage P1.
, the shutoff valve 13, the oil passage P2, the piston chamber 54, the mechanical seal device 51, and the oil passage 85 before flowing into the oil chamber 22.

As a result, the eccentric adjustment piston 21 protrudes and moves to eccentrically move the eccentric ring 32 to the maximum eccentric position, and the discharge amount of the plunger pump 12 becomes large (steady state).

When the discharge pressure of the plunger pump 12 increases due to stopping the movement of the load connected to the output boat PO of the plunger pump 12 and reaches the set pressure of the cutoff valve 13, the cutoff valve 13 is activated and the oil passage P1 and the oil passage P2, and the pressure oil from the discharge port 12b is not supplied to the oil chamber 22.

Thereafter, when the pressure further increases and reaches the set pressure of the unload valve 14, the unload valve 14 is operated and the pressure oil in the oil chamber 22 flows out from the oil passage P2 to the drain boat PD via the oil passage P3. As a result, the eccentric adjustment piston 21 moves to contract, and the discharge amount of the plunger pump 12 becomes extremely small (cut-off state).

When the flow rate increases due to load movement or the like and the discharge pressure from the discharge port 12b decreases, the cutoff valve 13 and the unload valve 14 return to the non-operating state, and the eccentric adjustment piston 21 moves to protrude again, thereby increasing the pressure of the plunger pump 12. Operation returns to steady state.

According to the above-mentioned embodiment, since the plunger block 77 having the plunger 33 is attached to the housing 71, it is possible to increase the number of plunger blocks 77 to increase the discharge amount and obtain pressure oil without pulsation. can. In addition, since the shaft 31 is only equipped with the eccentric adjustment piston 21, etc., the structure of the shaft 31 is simple and compact, and the overall structure can be made compact, and the shaft 31 can be rotated at high speed. The amount of discharge can be increased.

In addition, since the diameter of the eccentric ring member 32a is smaller than that of the conventional one, and the outer circumferential surface of the eccentric ring member 32a only needs to be machined with high precision, the eccentric ring member 32a can be easily machined, making it suitable for high-pressure radial pistons. It is possible to set it as pump 1.

According to the embodiment described above, when the load operated by the pressure oil discharged from the plunger pump 12 reaches the end of the process and stops, the discharge amount of the plunger pump 12 is automatically reduced, and thereby the radial piston pump 1 Alternatively, it is possible to prevent a rise in temperature of the hydraulic system and waste of energy, and it is also possible to prevent deterioration of pressure oil and equipment due to rise in temperature. Furthermore, since temperature rise is prevented, the cooling device can be made smaller and cost can be reduced.

In the above embodiment, the discharge port 11b of the gear pump 11
A low-pressure output port may be provided for outputting low-pressure oil from. In that case, a relief valve with an appropriate pressure may be connected to the low pressure output port.

In the above embodiment, the gear pump 11, plunger pump 12, cutoff valve 13, unload valve 14, mechanical seal device 51, shaft 31, housing cap 7
0. The structure, shape, size, material, etc. of each part of the housing 71 and the like may be various other than those described above.

〔Effect of the invention〕

According to the present invention, the plunger is attached to a housing, etc., and the eccentric adjustment piston is simply attached to the shaft, so the structure of the shaft is simple and compact, and the overall structure can be made compact. At the same time, the shaft can be rotated at high speed to increase the discharge amount.

Furthermore, since the diameter of the eccentric ring is smaller than that of conventional ones and the eccentric ring can be easily machined, the radial piston pump can be made suitable for high pressure applications.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional front view of a radial piston pump according to the present invention, FIG. 2 is a cross-sectional front view showing a part of the radial piston pump of FIG. Figure 4 is a diagram schematically showing the structure of the radial piston pump according to the present invention, and Figure 5 is a hydraulic circuit diagram of the radial piston pump according to the present invention. It is. ■... Radial piston pump, 21... Eccentric adjustment piston, 31... Shaft, 32... Eccentric ring, 33... Plunger, 34... Compression spring (biasing member).

Claims (1)

[Claims] (1) An eccentric ring provided to rotate integrally with a rotationally driven shaft and movable in a radial direction with respect to the shaft; and an eccentric ring provided on the shaft to make the eccentric ring eccentric with respect to the shaft. an eccentric adjustment piston that is driven to move in a radial direction; a biasing member that is provided on the shaft and that biases the eccentric ring in a direction opposite to the driving direction of the eccentric adjustment piston; A radial piston pump comprising a plurality of plungers arranged radially and reciprocated by the rotation of the eccentric ring.