JP3558416B2 - Pump discharge pressure pulsation reduction mechanism - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a mechanism for reducing pulsation of pump pressure in a plurality of pumps having different discharge pressure phases, such as two flows per cylinder block or a dual pump.
[0002]
[Prior art]
Mechanisms for reducing the pulsation of the discharge pressure of the pump include an expansion cavity type, a Helmholtz resonance type, and a branch pipe type. For example, in the expansion cavity type, the diameter of a part of the discharge side pipe is enlarged to increase the capacity of the pipe, and the pressure pulsation due to pressure loss and turbulence caused by suddenly expanding the flow of fluid flowing through the expansion part is smoothed. I am trying to do it. Similarly, the Helmholtz resonance type and the branch pipe type change the capacity of the pipeline in the discharge side pipeline to resonate or smooth the pressure pulsation by utilizing the phase delay.
[0003]
[Problems to be solved by the invention]
However, in the expansion cavity type, the diameter of a part of the discharge-side pipe is increased to increase the capacity of the pipe, and a sudden increase in the flow of the fluid flowing through the expansion section causes a pressure loss and a disturbance in the flow of the fluid. Since pressure pulsations are smoothed, it is necessary to rapidly expand the flow and recover the flow after expansion, and also require a structure in which the casing has pressure resistance as a pressure vessel to handle high pressures Therefore, it must be relatively large and strong. Further, there is a problem that the efficiency of the pump to be discharged becomes low because the pressure loss of the fluid is utilized. Further, in the Helmholtz resonance type or the branch pipe type, since the resonance is performed by changing the capacity of the pipeline in the discharge side pipeline or a phase delay is used, the pulsation frequency is relatively narrow. There is a problem that there is no effect of reducing the pulsation only in the band, and since it is installed in the piping, extra mounting members and joints are required, and a wide piping space is required.
[0004]
In particular, if these pulsation absorbing mechanisms are applied to a pump having two discharge pressure characteristics, such as a one-cylinder block two-flow type or a dual pump, it is necessary to install them in each discharge system. The installation space is also required, and it is inevitable that the pump becomes larger and heavier.
[0005]
An object of the present invention is to reduce the pulsation of the discharge pressure of a pump having two different discharge pressure characteristics, in particular, to provide a reduction mechanism built in the pump body and to reduce the size of the piping without requiring piping space.
[0006]
[Means for Solving the Problems]
The first invention is a first cylinder block 2 flow type pump with two different discharge pressure characteristic phases, and two discharge ports discharge pressure having different phases provided on the port block of the pump is introduced, the A cylinder communicated with the discharge port through a passage and two pressure absorbing chambers defined through a free piston housed in the cylinder are built in the pump body, and pressure absorption at both end surfaces of the free piston is performed. The discharge pressures having different phases are introduced into the chamber through the passages.
[0007]
In a second aspect based on the first aspect, a spring for urging the free piston in one direction is interposed.
[0008]
According to a third aspect of the present invention, in the first aspect, two free pistons are interposed in the cylinder, a compression spring is interposed between the free pistons, and a phase is provided in each of the pressure absorbing chambers defined by the free pistons. Different discharge pressures are introduced.
[0009]
[Action]
In the first aspect of the invention, the pump discharge pressure of the two different systems having position phase is introduced into each of the pressure absorbing chamber which is defined by the free piston from the discharge port. Since the phases of the discharge pressures are different from each other, such as when the discharge pressure of one pressure absorption chamber rises and the discharge pressure of the other decreases, the free piston moves in accordance with these pressure differences, and the free piston always moves to the high pressure side. To increase the volume of the pressure absorption chamber. In this way, the expansion of the volume of the pressure absorbing chamber communicating with the discharge port having the higher discharge pressure mitigates the absorption peak of the discharge pressure, and these are alternately repeated, whereby the pulsation of the pump discharge pressure is reduced. Reduced.
[0010]
Since the volume of each pressure absorbing chamber expands and contracts reciprocally, it is sufficient to provide only one cylinder and a free piston to absorb the pressure pulsation of the discharge pressure of two systems having different phases. The pump can be built in the pump body without taking up a large occupied space in the section, and it is possible to avoid an increase in the size and weight of the pump.
[0011]
According to the second aspect of the present invention, since a spring for urging the free piston in one direction is interposed, the responsiveness of the free piston is adjusted by the spring, and a discharge pressure pulsation matching at least one of the discharge pressure characteristics is exhibited. The vibration and the like of the free piston are suppressed by the spring, and the collision noise can be reduced.
[0012]
In the third invention, since two free pistons are interposed in the cylinder and a compression spring is interposed between the free pistons, the responsiveness of the two free pistons to the discharge pressure is adjusted by the spring, and the discharge pressure is reduced. The rise can be made smooth, and the vibration and the like of the free piston can be individually suppressed to reduce the collision noise.
[0013]
【Example】
1 to 4 show an embodiment of the present invention. FIG. 1 is an overall sectional view of the present invention, and FIG. 2 is an enlarged sectional view.
[0014]
This embodiment is an example in which the present invention is applied to a single cylinder block / two-flow type swash plate type piston pump. A cylinder block 3 that rotates integrally with a shaft 2 is provided in a casing 1. In the cylinder block 3, two systems of a plurality of pistons 4 and cylinders 5 are arranged at equal intervals on different circles around the shaft 2 respectively.
[0015]
When the cylinder block 3 rotates via the shaft 2 which is rotated by the power of a motor or the like, each piston 4 reciprocates in the cylinder 5 while abutting on the thrust plate on the swash plate 6, and the hydraulic oil Is supplied / discharged via a valve plate 7, and hydraulic oils having different phases of discharge pressures P 1 and P 2 to pistons 4 respectively provided on the inner peripheral side and the outer peripheral side to respective discharge ports 9 a and 9 b provided in a port block 8. Is discharged.
[0016]
FIG. 2 is an enlarged cross-sectional view of the port block 8 of the piston pump. Oil compressed by reciprocating motion of each piston 4 passes through inner and outer discharge holes 11a and 11b formed in the valve plate 7 through passages 12a and 12b. It is discharged to each port 9a, 9b via 12b.
[0017]
A cylinder 15 is formed in a part of the port block 8, and a free piston 16 is slidably fitted in the cylinder 15, and defines pressure absorption chambers 14a and 14b on both sides thereof. Note that one end of the cylinder 15 is sealed by a plug 18 via a sealing material 17. The pressure transmitting passages 13a, 13b branched from the passages 12a, 12b are connected to the two pressure absorbing chambers 14a, 14b of the cylinder 15, and the end surfaces of the free piston 16 are connected to the discharge ports 9a, 9b. The discharge pressure acts.
[0018]
Oil leakage from the gap between the free piston 16 and the cylinder 15 flows through the drain hole 19 to the low pressure side.
[0019]
The configuration is as described above, and the operation will be described next.
[0020]
The piston 4 disposed on the inner peripheral side of the cylinder block 3 and the piston 4 disposed on the outer peripheral side reciprocate with different phases, and accordingly discharge hydraulic oil with different discharge pressures P1 and P2. I do. This situation is shown in FIG.
[0021]
The discharge pressures P1 and P2 are guided to the pressure absorbing chambers 14a and 14b of the cylinder 15, and move the free piston 16 according to the pressure difference. When the discharge pressure P1 is higher than the discharge pressure P2, the free piston 16 strokes upward in the drawing to increase the volume of the absorption chamber 14a. On the other hand, when the discharge pressure P2 becomes higher than the discharge pressure P1, the free piston 16 moves in the opposite direction to increase the volume of the pressure absorbing chamber 14b.
[0022]
In other words, the free piston 16 receives the higher pressure of the discharge pressure P1 and the discharge pressure P2 having different phases, and strokes, thereby increasing the volume of the pressure absorption chamber 14a or the pressure absorption chamber 14b. Therefore, the peak of the discharge pressure on the high pressure side is absorbed and alleviated by the expansion of the volume, and the pressure pulsation is smoothed.
[0023]
In this case, since the pressure absorption chambers 14a and 14b are reciprocally expanded and contracted by guiding the discharge pressures of two systems having different phases to the same cylinder 15, the volume required for pulsation absorption has a single discharge characteristic. It may be the same as that applied to the pump, and eventually the total volume can be small, and the pressure pulsation can be reduced efficiently, which also contributes to downsizing of the pump.
[0024]
Next, a second embodiment will be described. As shown in FIG. 3, a cylinder 22 is formed in the port block 8, and a free piston 20 slidable on the cylinder 22 is provided on one side by a spring 21. It is urged toward the pressure absorbing chamber 14b.
[0025]
The pressure absorption chamber 14b side of the cylinder 22 is sealed with a plug 18 via sealing materials 17 and 26. The pressure absorbing chambers 14a and 14b are communicated with each other via pressure transmitting passages 13a and 13b branched from the passages 12a and 12b, respectively. The pressure absorbing chambers 14a and 14b at the end faces of the free piston 20 have ports 9a and 9b, respectively. 9b, the discharge pressure P1 and the discharge pressure P2 act.
[0026]
Accordingly, the discharge pressure P1 of the piston 4 disposed on the inner peripheral side of the cylinder block 3 acting on the pressure absorbing chamber 14a becomes higher than the discharge pressure P2 of the piston 4 disposed on the outer peripheral side acting on the pressure absorption chamber 14b. When the acting force of the spring 21 is further exceeded, the free piston 20 strokes, increasing the volume of the pressure absorbing chamber 14a. Thereby, the pressure pulsation of the discharge pressure P1 is absorbed. Conversely, when the discharge pressure P2 becomes larger than the discharge pressure P1, the free piston 20 moves quickly in the opposite direction, and also absorbs the pressure pulsation of the discharge pressure P2. I do.
[0027]
In this case, the spring 21 suppresses the vibration and the like of the free piston 20 and can reduce the collision noise.
[0028]
Further, in the third embodiment, as shown in FIG. 4, the free piston 20 in the second embodiment is separated into two free pistons 30, 31, and a compression spring 21 is provided between the free piston 30 and the free piston 31. It is interposed.
[0029]
When the discharge pressure P1 acting on the pressure absorbing chamber 14a and the discharge pressure P2 acting on the pressure absorbing chamber 14b are extremely low, the free pistons 30, 31 are urged toward the pressure absorbing chambers 14a, 14b by the force of the spring 21. Thus, a certain gap is maintained between the free pistons 30 and 31, but when the discharge pressures P1 and P2 exceed the spring 21 force, the free pistons 30 and 31 integrally stroke. In this case, when the discharge pressure P1 becomes higher than P2, the free piston 30 moves while pressing the free piston 31, and increases the volume of the pressure absorbing chamber 14a.
[0030]
When the discharge pressure P2 acting on the pressure absorbing chamber 14b becomes higher than the discharge pressure P1 acting on the other pressure absorbing chamber 14a, the free piston 31 increases the volume of the pressure absorbing chamber 14b while pushing the free piston 30. Thus, in the same manner as described above, the pulsation of the pump discharge pressure of the two systems having different phases is absorbed and reduced.
[0031]
In the embodiment of the present invention, the pulsation reducing mechanism is applied to a pump that outputs two systems of discharge pressures having different phases to one cylinder block. Even when a plurality of pumps are used, the pulsation reduction mechanism of the present invention can be applied to the pulsation reduction of a pump in which the pump discharge pressures are output in different phases.
[0032]
【The invention's effect】
According to the first invention, the pump discharge pressure of the two different systems having position phase, when the discharge pressure of one of the pressure absorbing chamber is increased, so that the other discharge pressure decreases, the discharge pressure of the phase Are different from each other, the free piston moves in accordance with these pressure differences, and always enlarges the volume of the pressure absorption chamber on the high pressure side. Thus, the pressure communicating with the discharge port having the higher discharge pressure is increased. the volume expansion of the absorption chamber, the peak of the discharge pressure is absorbed alleviated, by which they are alternately repeated, the pulsation of the pump ejection discharge pressure is effectively reduced, especially the volume of the pressure absorbing chamber is reciprocally scaling since, to absorb the pressure pulsations of the two different systems of discharge pressure phases, it is only provided with one cylinder and the free piston, without taking a large space occupied by the part, such as the for the pump casing, the pump It is possible to built the body, such as size and large weight of the pump can be avoided.
[0033]
According to the second aspect of the present invention, since the spring for urging the free piston in one direction is interposed, the response of the free piston is adjusted by the spring, and the effect of absorbing the discharge pressure pulsation matching at least one of the discharge pressure characteristics is achieved. , And vibration of the free piston is suppressed by the spring, so that the collision noise can be reduced.
[0034]
According to the third aspect, since two free pistons are interposed in the cylinder and a compression spring is interposed between the free pistons, the responsiveness of the two free pistons to the discharge pressure is adjusted by the spring, and the discharge is adjusted. The rise of the pressure is smoothed, and the vibration of the free piston is individually suppressed, so that the collision noise can be reduced.
[Brief description of the drawings]
FIG. 1 is an overall sectional view showing an embodiment of the present invention.
FIG. 2 is an enlarged sectional view of the same.
FIG. 3 is an enlarged sectional view of the second embodiment.
FIG. 4 is an enlarged sectional view of the third embodiment.
FIG. 5 is an explanatory diagram showing discharge pressure characteristics of two pumps at different phases.
[Explanation of symbols]
Reference Signs List 1 casing 2 shaft 3 cylinder block 4 piston 5 cylinder 6 swash plate 7 valve plate 8 port block 9a discharge port 9b discharge port 11a discharge hole 11b discharge hole 12a passage 12b passage 13a pressure transmission passage 13b pressure transmission passage 14a pressure absorption chamber 14b pressure Absorption chamber 15 Cylinder 16 Free piston 20 Free piston 21 Spring 30 Free piston 31 Free piston P1 Discharge pressure P2 Discharge pressure

Claims (3)

In one cylinder block 2 flow type pump with two different discharge pressure characteristic phases, through the two discharge ports discharge pressure having different phases provided on the port block of the pump is introduced, the passage from the discharge port different and communicated with the cylinder, via a free piston which is accommodated in the cylinder and two pressure absorbing chamber which is defined, with each via the passage to the pressure-absorbing chamber opposite end faces of the free piston phase Te A pump discharge pressure pulsation reduction mechanism built into the pump body that introduces discharge pressure. The pump discharge pressure pulsation reduction mechanism according to claim 1, further comprising a spring for urging the free piston in one direction. 2. The cylinder according to claim 1, wherein two free pistons are interposed in the cylinder, a compression spring is interposed between the free pistons, and discharge pressures having different phases are respectively introduced into the pressure absorbing chambers defined by the respective free pistons. A pulsation reduction mechanism for the pump discharge pressure.

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