JPH02218871A - Radial piston pump - Google Patents

Abstract

PURPOSE:To prevent the temperature increase of a device by controlling an eccentric member to automatically reduce the discharge of a pump when the discharge side pressure becomes a set value or more in a one capable of varying the moving stroke of a plunger according to the eccentric amount of the eccentric member. CONSTITUTION:In a variable capacity plunger pump 12, a plurality of plungers radially provided around a ring eccentric member mounted on a driving shaft are reciprocally moved by the rotation of the eccentric member to discharge a fluid. The discharge can be varied by regulating the eccentric amount of the eccentric members by the movement of an eccentricity regulating piston 21. In this case, a cutoff valve 13 closed when the discharge pressure becomes a set value or more is connected between a pump discharge opening 12b and an oil chamber 22 pressing the eccentricity regulating piston 21. An unload valve 14 leaking the pressure of the oil chamber 22 when the discharge pressure becomes a pressure operating the cutoff valve 13 or more is connected between the oil chamber 22 and a drain port PD connected to an oil tank.

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 plunger 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.

With conventional radial piston pumps like this, even when the load operated by the pressure oil discharged from the pump reaches the end of the process and only maintains that state, the discharge volume does not automatically decrease. The problem is that almost the entire amount of high-pressure oil discharged from the pump is relieved while maintaining a constant pressure, and the heat generated by this causes the temperature of the entire device to rise, and also wastes energy. was there.

In view of the above-mentioned problems, the present invention provides a radial system that automatically reduces the pump discharge amount when the pump discharge pressure reaches a certain set value, thereby preventing the temperature rise of the device and the waste of energy. The purpose is to provide piston pumps.

[Means to solve the problem]

In order to solve the above-mentioned problem, the invention of claim 1 is such that the reciprocating stroke of the plunger is varied in accordance with the eccentricity of the eccentric member moved by the movement of the eccentricity adjusting piston, and the amount of oil discharged by the plunger is varied. In a radial piston pump, the discharge side that discharges pressure oil by the reciprocating movement of the plunger is connected between the oil chamber that presses the eccentric adjustment piston, and is normally in communication so that the pressure on the discharge side is equal to or higher than a set value. and an unload valve that releases the pressure oil in the oil chamber when the pressure on the discharge side exceeds the pressure at which the shutoff valve operates. be done.

The invention of claim 2 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 and that is provided with respect to the shaft. an eccentric adjusting piston that is driven to move in an eccentric radial direction; a biasing member provided on the shaft that urges the eccentric ring in a direction opposite to the driving direction of the eccentric adjusting piston; and an axial position of the eccentric ring; A plurality of plungers provided radially in a radial direction and reciprocated by the rotation of the eccentric ring are connected between a discharge side that discharges pressure oil by the reciprocating movement of the plungers and an oil chamber that presses the eccentric adjustment piston. , a cutoff valve that is normally in communication and operates to shut off when the pressure on the discharge side exceeds a set value, and a cutoff valve that operates when the pressure on the discharge side exceeds the pressure at which the cutoff valve operates. It is configured with an unload valve that releases pressure oil in the oil chamber.

[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.

The shutoff valve communicates and guides pressure oil to the oil chamber when the discharge pressure from the plunger is low, but operates to shut off the flow when the discharge pressure exceeds a set value.

The unload valve releases the pressure oil in the oil chamber when the pressure becomes higher after the shutoff valve is activated, and causes the eccentric adjustment piston to move and contract.

As the eccentric adjustment piston contracts and moves, the amount of eccentricity of the eccentric ring decreases, and the amount of discharge by the plunger decreases.

〔Example〕

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

FIG. 5 is a hydraulic circuit diagram of a radial piston pump l 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 cutting off pressure oil to the oil chamber 22, and a drain valve 13 for supplying or shutting off pressure oil to the oil chamber 22;
It consists of an unload valve 14 that releases air to D, etc.

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
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 and the pilot flow path 13c of the shutoff valve 13 is connected to the discharge port 12b, and between the oil chamber 22 and the Drainbow PD connected to the oil tank Unload valve 14 is connected, unload valve 1
The No. 4 pilot flow path 14c is connected to the discharge port 12b. In addition, a throttle valve 15°1 for preventing chuckling 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 PD through the unload valve 14, and the eccentric adjustment piston 21 contracts and moves.

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 31 rotationally driven by a shaft 31, an eccentric ring 32 provided to rotate integrally with the shaft 31 and movable in a radial direction relative to the shaft 31, and an eccentric ring 32 provided radially in 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 6-2 to close the valve seat 63, and the hard ball 6I.
It has a balance piston 64 that pushes the valve open when the pressure in the pilot flow path 14c becomes higher than a set value.

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 paper in FIG. 1 with respect to the unload valve 14 shown in FIG. 1. Furthermore, in FIG. 3, the housing cap 7 of the radial piston pump l shown in FIG.
0 and the housing 71 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 mounted on the plunger pump shaft portion 31a in radially opposite directions. It is set facing. 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 32f.
and a needle bearing 3 attached to the outer peripheral surface of the eccentric ring member 32a.
2b.

The housing 71 is provided with holes 76 for radial plunger attachment at a plurality of locations equally divided in the circumferential direction, and a plunger block 77 is attached to each of the plunger attachment holes 76.

In the plunger block 77, the above-mentioned L Tough' plunger 33 is inserted into a cylindrical plunger chamber 79 connected to the check valve 35.
It is configured to be biased outward (in the axial direction of the shaft 31) by.

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 plunger 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 12b. Discharges pressure oil to.

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 outer 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 951 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 70a 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 when the pressure in the pilot flow path 14c becomes higher than the pressure set by the compression spring 52, The balance piston 64 moves to the right in FIG. 1 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 no longer supplied to the oil chamber 22.

After that, the pressure further increases and when it reaches the set pressure of the unload valve 14, the unload valve 14 is activated and the pressure oil in the oil chamber 22 flows out from the oil path P2 to the drainbaugh PD via the oil path 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 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.

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.

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-described embodiment, the gear pump 11, plunger pump 12, cutoff valve 13, unload valve 14, mechanical seal device 51, shaft 31, housing cap 70
The structure, shape, size, material, etc. of each part such as the housing 71 can be made into various things other than those described above.

〔Effect of the invention〕

According to the present invention, when the discharge pressure of the pump reaches a certain set value, the discharge amount of the pump is automatically reduced, thereby preventing a rise in temperature of the device and wasting energy.

[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. FIG. 4 is a diagram schematically showing the structure of the radial piston pump according to the present invention, and FIG. 5 is a hydraulic circuit diagram of the radial piston pump according to the present invention. be. DESCRIPTION OF SYMBOLS 1... Radial piston pump, 12b... Discharge port (discharge side), 13... Shutoff valve, 14... Unload valve, 31... Shaft, 21... Eccentricity adjusting piston, 22... ...Oil chamber, 32...Eccentric ring (eccentric member)
, 33... plunger, 34... compression spring (biasing member).

Claims (2)

[Claims] (1) In a radial piston pump in which the reciprocating stroke of a plunger is varied according to the eccentricity of an eccentric member moved by the movement of an eccentric adjustment piston, and the amount of oil discharged by the plunger is varied, the pressure is increased by the reciprocating movement of the plunger. A shutoff valve is connected between a discharge side that discharges oil and an oil chamber that presses the eccentric adjustment piston, is normally in communication, and operates to shut off when the pressure on the discharge side exceeds a set value. and an unload valve that releases pressure oil in the oil chamber when the pressure on the discharge side exceeds the pressure at which the shutoff valve operates. (2) An eccentric ring provided to rotate integrally with a rotationally driven shaft and movable in a radial direction with respect to the shaft; and a radius at which the eccentric ring provided on the shaft is eccentric with respect to the shaft. an eccentric adjustment piston that is driven to move in a direction; a biasing member that is provided on the shaft and that biases the eccentric ring in a direction opposite to the direction in which the eccentric adjustment piston is driven; A plurality of plungers provided in the holder and reciprocated by the rotation of the eccentric ring are connected between a discharge side that discharges pressure oil by the reciprocating movement of the plungers and an oil chamber that presses the eccentric adjustment piston, and are normally in communication. and a shutoff valve that operates to shut off when the pressure on the discharge side exceeds a set value, and a pressure in the oil chamber that operates when the pressure on the discharge side exceeds the pressure at which the shutoff valve operates. A radial piston pump characterized by having an unload valve for releasing oil.