JPS60243379A - Variable displacement pump - Google Patents

Abstract

PURPOSE:To permit to regulate reduction of noise during operation by a method wherein a valve device, regulating the opening degree for communicating an unit pump chamber under sealed period with the pump chamber under suction or delivery period among the plurality of pump chambers whose displacements are changed continuously, is provided in the pump. CONSTITUTION:A swash plate type piston pump 1 is provided with a plurality of pump chamber 4, whose displacements are varied by the reciprocating motion of a piston 5, slidingly contacted with a rotary swash plate 8 at one end thereof, in accordance with the revolving motion about a rotary shaft 2. The slant angle of a swash plate 8 is controlled by a delivery amount control mechanism including an operating piston 11 while the delivery control mechanism is controlled by a pressure control valve 18 into a direction wherein the difference of displacement becomes zero when a delivery pressure has arrived at a set cut-off pressure. In this case, the valve device 27, being operated by a control hydraulic pressure operating the operating piston 11 which comes from an oil path 23 through the oil path 26, is provided and the control of opening and closing of the communications between the pump chambers 4 may be effected by the valve device 27 through a port plate 12.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a variable displacement pump, and particularly to noise reduction thereof. This invention relates to a hydraulic variable displacement pump that has been improved to reduce hydraulic pressure.

[Prior art]

In order to measure the noise reduction of a hydraulic variable displacement pump, multiple unit pump chambers whose volume changes as they orbit around the rotation axis cause rapid pressure changes in each sealed section between top dead center and bottom dead center. In order to avoid this, the pressure should be gradually changed between the suction section and the discharge section, which are separated by these sealed sections.
It is shown in the publication No.-42882.

In other words, in a conventional variable displacement pump of this type, an extraction port for relaxing pressure changes is provided on the rotating swash plate side so that the degree of pressure relaxation changes according to changes in the discharge amount, and the pressure changes depending on the angle of the swash plate. The opening degree of this extraction port is made to change.

[Problems to be solved]

By the way, when you change the pump rotation speed in a variable displacement pump like this, for example, the gradient of pressure change between the top and bottom dead center changes due to the change in rotation speed, so as the rotation speed increases, the pressure changes suddenly. On the other hand, the one disclosed in the above-mentioned publication has no corresponding irregularity, and inevitably has the disadvantage that it generates a lot of noise when used at a rotation speed other than the determined rotation speed, especially at a high rotation speed. In addition, with this product, it is possible to optimally set both the noise reduction at the maximum tilting angle of the swash plate and the noise reduction at full cut-off (swash plate tilting angle Σ0), but once the pump is set, it is possible to set the noise reduction during use. Replace parts to change settings! fA
There is no choice but to make adjustments to reduce the noise when the pump is discharging at a constant discharge pressure, which is not always at the optimum setting. There is also a drawback that there is no.

[Summary of the invention]

In order to eliminate these five drawbacks of the conventional ones, the present invention provides a valve that has a function of replacing the extraction port for alleviating pressure changes when the pump is operated by the control pressure of the pump itself for controlling the pump discharge pressure. A device is attached to the valve device, and the valve device is designed to control the opening/closing degree of communication between the unit pump chamber in the sealed section and the unit pump chamber in the suction or discharge section immediately before or immediately before the valve device is operated. This provides a variable displacement pump that operates at a preset communication opening when not in operation, and by adjusting the communication opening using the manual of the ERI valve device, the optimal state for noise reduction can be achieved at the operating speed. It is designed to be able to respond to changes and to always provide optimal low-noise operation.

That is, a plurality of unit pump chambers whose volume changes as they orbit around the rotation axis; A boat defining, for one revolution, each sealed section at a top dead center and a bottom dead center for the unit pump chamber, and a suction section communicating with a pump suction boat and a discharge section communicating with a pump discharge boat, which are separated from each other by these sealed sections. Plate: A discharge amount control function that gives the unit pump chamber a minimum volume at the top dead center and a maximum volume at the bottom dead center, and changes the volume difference of the unit pump chamber between the top and bottom dead centers; and a pump discharge pressure. a pressure control mechanism that operates the discharge amount control mechanism in a direction in which the volume difference becomes zero when the pump reaches a preset cutoff pressure; Accordingly, in a variable displacement pump equipped with minute oil guiding means provided at the end portion of each sealed section of the boat plate so as to gradually communicate with the unit pump chamber in the immediately following suction or discharge section, In the first invention of the present application, the pressure control mechanism is operated together with the discharge amount control mechanism, and the unit pump chamber before the area and the suction or discharge immediately after the area that opens in the suction or discharge zone immediately after each sealed zone are operated together with the discharge rate control mechanism. It must have a valve device that controls the opening and closing of communication with the unit pump chamber within the section, and whose degree of communication opening during operation can be adjusted. The characteristics include the boat angle of each sealed section of the boat plate and the maximum volume difference of the oil guiding means. If the design is such that the noise value is minimized in the given state (maximum discharge amount state), lc.

The pressure change in the unit pump chamber in one or both of the sealed sections on the top dead center or bottom dead center side can be alleviated to a desired degree of change that can be manually adjusted in a state that provides a minimum volume difference (full cutoff state). Yes ↓ 5.

Further, in the second invention of the present application, the pressure control mechanism operates together with the discharge amount control mechanism, and the unit pump chamber and each of the sealed sections before opening to the immediately following suction or discharge section in each sealed section. It is characterized by having a valve device which opens and closes communication with the unit pump chamber in the discharge or suction section immediately before the boat plate, and whose degree of communication opening when not in operation can be adjusted. The boat angle of each sealed section of The pressure change in the unit pump chamber in one or both of the sealed sections can be alleviated to a desired degree of change that can be manually adjusted in a state where the maximum volume difference is given (maximum discharge amount state).

〔Example〕

To show an embodiment in which the great invention is applied to a swash plate type piston pump, FIG. 1 shows an embodiment of the first invention, in which the variable displacement pump (1) is a well-known swash plate type piston pump,
Cylinder lock +3 rotated by rotating shaft (2)
1 has a plurality of cylinder chambers (4) facing in the axial direction, and a piston (51) is inserted into each of the cylinder chambers (4).The piston (5) has a universal joint at the end. The slip shoe (61), which is formally connected to the slip shoe (6), is pivotally supported by the hitot (7) on the rotating shaft (21) and is supported in contact with the rotating swash plate T81.

The rotating swash plate (8) is supported by a yoke (10) elastically biased by a spring (9) at the lower part thereof, and the yoke (10) is elastically biased by a spring (9).
0) The tilting angle of the swash plate (8) can be changed by tilting the swash plate (8) against the spring (9) using the V-operated piston (11). Therefore, when the swash plate (8) is tilted, the rotating shaft (21 pieces) is rotated, and the cylinder block [3] is moved around the rotating shaft together with the piston (5).

The stroke of the piston (5) changes as it rotates, and the kneading causes the volume of the cylinder chamber (4) to change as it rotates. The other end of the cylinder block (31) is supported by a non-rotating boat plate (i2),
This boat brake) (12) is for each cylinder chamber (4)
and pump suction boat) (13) and discharge boat (1
For convenience of explanation, the valve plate between the cylinder block (3) and the cylinder block (3) is shown as a valve plate between the cylinder block (3) and the cylinder chamber (3). For 4),
Top dead center (T side closed section (CT), bottom dead center (BL side closed section (CB), and these closed sections (CT) (CB)
A suction section fsl and a discharge section (D) are defined, and the suction section fs+ has a suction port (15) communicating with the suction port (13), and the discharge section () has a discharge port (14). ) are each formed in an arcuate shape. The yoke (1CI) and the swash plate tilting mechanism as the main body constitute a discharge amount control mechanism, which controls the minimum volume at the top dead center mountain with respect to the cylinder chamber (41) and the maximum volume at the bottom dead center (marked). It is well known that the discharge amount is changed by changing the volume and changing the tilt angle of the swash plate, that is, by changing the volume difference of the cylinder chamber (4) between the top and bottom dead centers.Yoke (,1 ()) The retraction piston (11), which is tilted against the Y spring (9), has its rear end regulated by a maximum discharge amount adjustment screw (17), and has a pressure control at its tail end. The reduced pump discharge pressure applied through the pressure control section (18) is applied to the spool ( When the discharge pressure acting on the spool (20) reaches the cut-off pressure set by the spring (22) whose spring force is adjusted by the maximum discharge pressure adjustment screw (21), the spool (20) acts against the spring (22). An oil passage (
23)'la0: Open, part of the pump discharge pressure acts on the tail end of the piston (11X/), thereby causing the piston (
11) is tilted in the direction in which the yoke (10) l&the volume difference approaches zero. (stand up) Now, in the boat play (12) shown on the right side of Figure 1, the block boat position of the cylinder chamber (41) in the sealed section tCT) (CB) is indicated by the broken line (4a) (4
b), in which case the block boat has just entered the closed section. From this time until the tip of the block boat moves clockwise on the boat plate and begins to open to the suction port (15) or the discharge port (16), the cylinder is closed in the top dead center side closed section (CT). 11 The pressure in the chamber (4) gradually decreases to the suction port (15).
The pressure will drop to 5, and the closed section on the bottom dead center side (CB
), the pressure inside the cylinder chamber (4) gradually increases to the discharge port (1).
6) are provided with minute oil guide passages or oil guide holes (24, 25) such as V-groove notches, respectively. The changes in cross-sectional area and length of the Kowara oil guide holes (24) and (25) in the circumferential direction and the length of the sealed section (boat angle) are as follows:
Depending on how the pump is used, it is predetermined in advance that the pump noise will be at its lowest at either the maximum discharge volume, the full cut-off state, or a certain point in between. It is fixedly set to only that state, and even if one state is satisfied, the noise may become higher in the other.

According to the present invention, in the improved pump, for example, the sealed section on the top dead center side is shown in FIG. 1, and the sealed section on the bottom dead center side is shown in FIG. 2. A valve device (27) that operates by guiding control pressure to operate the operating piston (11) Y through the oil path (26) Y is provided.

This valve device I (27) is operated simultaneously when the operating piston (11) h is operated by the pressure control unit (18).

The cylinder chamber (4) in the closed section (CT) or (CB) is connected to the suction port (15) in the suction section +81 immediately after it.
) or discharge section (before opening to the discharge port (16) of It controls the opening and closing of communication with the cylinder chamber (4) in the section, and the degree of communication opening can be set by manual adjustment separately for when the valve device (27) is inactive and when it is activated. That is, in FIG. 1 or 2.

The valve device (27) has a spool (60 mm) whose stroke is regulated by adjustment screws (28) and (29) at both ends, and the spool [
30] G1 has large diameter portions (31) (32) on both end sides and a small diameter portion (33) in the middle, between the large diameter portion (31) on the tip side and one adjustment screw (28) Oil road (26
) is introduced into the oil chamber between the large diameter part (62) on the tail end side and the other adjustment screw (29), and the pressure oil is introduced into the small diameter part (33) at the driving end. A tapered portion (32a) is formed at the shoulder of the side large diameter portion (62) to form a small diameter portion (36).
A pair of bows (34) and (35) in the aperture control section (66) are formed.

(34) is the suction port (15) in Figure 1.
In Fig. 2, the connection to the discharge port (16) is t'l=
HO) (65) is a boat brake)
4), and the opening (69) in front of the oil guide hole (25) in the bottom dead center side sealed section (CB) in Fig. 2.
) are open to each. The spool (60) has an oil path (
26), the control pressure comes into contact with one of the adjustment screws (28) by the return spring (g) in the non-operating state, and therefore the throttle control section (36) opens at this time. The opening degree can be manually set from zero (closed) to a desired opening degree using an adjustment screw (28). When control pressure arrives in the oil path (26), the spool (30)
The tail end of 9X is brought into contact with the aperture control section (
36) can be manually set using the other adjustment screw (29).

In the embodiment of the first invention of the present application having this simple configuration, in the pressure-flow characteristic of the pump shown in FIG. 3, until the discharge pressure reaches the cut-off pressure, the control section (
) & one of the adjustment screws (28) to open at the opening set, or if the set opening is zero, it is closed, so for example boat play) (12) will be at its optimum value when the discharge volume is at its maximum. If the pump is designed for the When changing the setting of the amount, similar setting adjustment is possible by manual adjustment of the adjusting screw (28). When the cut-off pressure is reached, the spool (30
) moves and the control part (36) opens at the opening set by another adjustment screw (29). By properly adjusting this opening, the oil guide hole (24) or By changing the effect of (25) using the parallel control unit (66), the optimum state of noise reduction can be obtained even in the cut-off state with the same boat plate. It can be manually adjusted while making actual measurements.

Figure 4 shows the pressure change in the cylinder chamber at full cut-off, where the solid line indicates the case where the valve device (27) is not equipped with Y, and the broken line on the top dead center side indicates the lower pressure in the case of the embodiment shown in Figure 1. The broken line on the dead center side corresponds to the embodiment shown in FIG.

FIG. 5 and FIG. 6 show the main parts of the embodiment of the second invention of the present application, and when FIG. 5 is applied to the top dead center side sealed section,
The application to the sealed section on the bottom dead center side is not shown in FIG. 6, and the same reference numerals are given to the same parts as in FIGS. 1 and 2, respectively.

The differences in Figures 5 and 6 from Figure 1 and Figure 2 are that the boat angle of the boat brake (12) and the oil guide holes (24) and (25) are at their lowest level in the full cut-off state. Designed to generate noise and valve equipment (27)
is normal oven type (spring (37) is on the opposite side)
The opening (68) in front of the oil guide hole (24) + 7) in the closed section (CT) on the top dead center side of the boat plate (12) is connected to the throttle control part (36) of the valve device (27). & connected to the discharge port (16), or the opening (39) in front of the bottom dead center side sealed section (C3)
is connected to the suction port (15) via the throttle control part (36)Y of the valve device (27), and the other is that the first
There is not much difference from those in Fig. and Fig. 2. Also in FIGS. 5 and 6, the adjustment screw (28) is used to adjust the opening during discharge, and the adjustment screw (29) is used to adjust the opening during full cut-off.

In the embodiment of the second invention of the present application having this elaborate configuration, the pressure-flow rate characteristics of the pump shown in FIG.

The valve device (27
) is the aperture control part (36) Y one adjusting screw (28)
It opens at the opening degree set by this adjustment screw (
1. By adjusting the speed of the pump, no matter what rotation speed the pump is driven at, the optimum condition for noise reduction can be obtained. The adjustment screw (28) can also be used to change the setting of the maximum discharge amount. When the cut-off pressure is reached, the spool (30) moves to the left in the figure using the hydraulic pressure from the oil passage (26), and the control section (36)'& throttles.

At this time, the aperture opening degree of the control unit (66) is determined using another adjustment screw (
29), and can also be set to close the control unit (36). Therefore, what is the effect of the oil guide hole (24) or (25) at the time of cut-off by adjusting the adjustment screw (29)? Since it can be changed, the Bonn 7' at different rotation speeds
During the ffi operation, it is possible to set the optimal state for noise reduction at cut-off by adjusting the adjustment screw (29), and the kneading device can also be manually adjusted while actually operating it and actually measuring the noise.

Figure 7 shows the pressure change in the cylinder chamber at maximum discharge (maximum swash plate inclination). In the case of the embodiment, the broken line on the bottom dead center side corresponds to the embodiment of FIG. 6, respectively.

In each of the embodiments shown in Fig. 1 #2-5.6 above, the spring (37) of the °C valve device (27) is connected to the spool (30 )v It was explained as a weak spring that is only used to return to the initial position, but by properly designing this spring (37) and the opening degree that corresponds to the change in control pressure from cutoff to full cutoff. It is also possible to change the aperture control port (36) to 5 to control the opening.

Furthermore, as an example of the use of the valve device (27), it is also unthinkable to reduce the noise of a constant discharge pump by reducing the discharge pressure and operating the valve device (27)Y.

In addition, in the above embodiment, the case was described where the design was based on the maximum discharge amount of the boat plater or the condition of the boat plate (1 full cut-off), but it was designed with the intermediate discharge amount condition as the base thread. Needless to say, it's a good thing.

[Effects of the Invention] As described above, in the variable displacement pump of the first invention of the present application, the pressure control mechanism for controlling the pump discharge pressure is operated in conjunction with the pump discharge rate control mechanism, and the The opening/closing side (goods) that communicates between the unit pump chamber before opening in the suction or discharge section and the unit pump chamber in the suction or discharge section immediately after the above, and the degree of communication opening during operation is adjusted and set. Because it has a valve device made possible,
The port angle of each sealed section of the boat plate as the valve board of each unit pump chamber is designed to minimize the noise value in the state where the oil introducing means is given the maximum volume difference (maximum discharge amount state). Even if the pressure changes in the unit pump chamber in one or both of the closed sections on the top dead center or bottom dead center side, the desired degree of change can be adjusted manually in the state that provides the minimum volume (full cut-off state). can be relieved,
Further, in the variable displacement pump of the second invention, the pressure control mechanism for controlling the pump discharge pressure similarly operates together with the pump discharge rate control mechanism, and opens in each sealed section to the immediately following suction or discharge section. A valve device that opens and closes communication between the previous unit pump chamber and the unit pump chamber in the discharge or suction section immediately before each of the sealed sections, and the degree of communication opening when not in operation can be adjusted. Therefore, the boat angle of each sealed section of the boat plate as a valve board of each unit pump chamber and the conduction means are set such that the noise value is minimized in a state (full cut-off state) that provides a minimum volume difference, for example. Even if the design is designed to
Therefore, the first and second inventions can reduce noise at either maximum spitting or full cut-off, which is determined by the design of the boat plate. Independently from the other state, the noise reduction effect can be manually adjusted to suit the pump rotation speed, discharge flow rate, and pressure.

Furthermore, manual adjustment of the stiffness can be carried out while actually measuring the noise under the operating conditions of the pump.

[Brief explanation of drawings]

Fig. 1 is a block diagram schematically showing the embodiment of the first invention 0), Fig. 2 is a block diagram showing the main parts of another embodiment, and Fig. 6 is a block diagram schematically showing the embodiment of the first invention.
The figure is a diagram showing an example of the pressure-flow characteristics of a variable volume pump.
FIG. 4 is a diagram showing the change in pressure inside the unit pump at full cut-off in the embodiments shown in FIGS. 1 and 2; FIG. 5 is a configuration M schematically showing the main part of the embodiment of the second invention; 6th
The figure is also a configuration diagram of the main part showing another implementation f9jl'i,
FIG. 7 is a diagram showing the change in pressure inside the unit pump at the maximum tilt angle of the swash plate in Example 1 shown in FIGS. 5 and 6. FIG. (1), variable displacement pump, +41 cylinder chamber (unit piston chamber), (10): swash plate, (11): operating piston, (12): port plate, (15C suction port,
(16): Discharge port, (18): Pressure control valve - (24)
(25): Oil guide groove (hole), C26): Oil passage, (27):
Valve device, (28) (29): Adjustment knob, (3 [1)
: :x Full, (36): Aperture h Ila section - (
3B) (39): Opening. Agent Patent Attorney Sanro Kimura

Claims (1)

[Claims] (1) A plurality of unit pump chambers whose volume changes with orbital movement around the rotation axis; non-rotationally arranged between these unit pump chambers and the pump suction/discharge boat; A boat plate defining, for a unit pump chamber, each sealed section at a top dead center and a bottom dead center, and a suction section communicating with a pump suction boat and a discharge/discharge section communicating with a pump discharge boat, which are separated from each other by these sealed sections; a discharge amount control mechanism that gives the unit pump chamber a minimum volume at the top dead center and a maximum volume at the bottom dead center, and changes the volume difference of the unit pump chamber between the top and bottom dead centers; a pressure control mechanism that operates the discharge amount side (goods) mechanism in a direction in which the volume difference becomes zero when a preset cutoff pressure is reached; a unit pump chamber located within the sealed section; A variable capacity variable capacity valve equipped with minute oil guiding means provided at the end of each sealed section of the boat plate to gradually communicate with the unit pump chamber in the suction or discharge section immediately after the rotation. In the pump. The units in the pump chamber and the units in the suction or discharge section immediately after are operated together with the discharge 1' control mechanism by the pressure control mechanism and open to the immediately following suction or discharge section within each sealed section. A variable displacement pump, characterized in that it has a valve device which controls the opening and closing of a V communicating with the inside of the pump chamber, and whose degree of communication opening during operation is rotated to adjust the setting (21. a plurality of unit pump chambers that change; non-rotationally arranged between these unit pump chambers and pump suction/discharge boats; each sealed section, and a boat plate separated from each other by these sealed sections and defining a suction section leading to a pump suction boat and a discharge section leading to a pump discharge boat; a discharge electric control mechanism that gives a maximum volume at the bottom dead center and changes the volume difference of the unit pump chamber between the top and bottom dead centers; when the pump discharge pressure reaches a preset cutoff pressure; a pressure control mechanism that operates the discharge amount control mechanism in a direction in which the volume difference becomes zero; a unit pump chamber located within the sealed section; In the variable capacity pump, the pressure control mechanism controls the discharge amount control mechanism and the boat plate 0. 11. In each sealed section, the unit pump chamber before opening in the suction or discharge section immediately after the sealed section and the unit pump chamber in the discharge or suction section immediately before each sealed section are opened and closed in communication with each other. With. A variable displacement pump characterized by having a valve device whose communication opening degree when the pump is not in operation can be adjusted.