JPH039086A - Variable delivery type pump - Google Patents

Abstract

PURPOSE:To reduce an exciting force and a noise level by keeping a kidney port eccentric about the center of a cylinder toward a trailing side, making the kidney port continuous to an intake port during the stroke where the cylinder near a piston bottom dead center becomes continuous to a delivery port. CONSTITUTION:A piston 3 so coupled into a cylinder 2 as to be freely slidable, gives reciprocal motion with the turn of a cylinder block 21. Concurrently, a kidney port 27 continuous to the cylinder 2 becomes continuous respectively to the intake and delivery ports 12 and 11 of a valve plate 8 with the rotation of the cylinder block 21. In this case, the kidney port 27 is so positioned as to be eccentric by the predetermined amount of (e) toward a trailing side in the progress of the cylinder block 21. In addition, the kidney port 27 is made directly continuous to the intake port 12 with the piston 3 at the bottom dead center, and further continuous to the delivery port 11 via a V-notch 13.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a variable displacement pump with reduced noise level.

<Prior Art> Conventionally, this type of variable displacement pump has been manufactured using the pumps of No. 5.6.
There is something like the one shown in Figure 7 (Utility Model No. 63156476
Publication No.). This variable displacement pump has cylinder block 1
A piston 3 is slidably fitted into a cylinder 2 provided in the cylinder 2, and this cylinder block l is rotated by a shaft 5,
The piston 3 is reciprocated by a stroke controlled by the swash plate 6, and a kidney port 7 communicating with the cylinder 2 is provided concentrically with the cylinder 2 as shown in FIG.
The kidney port 7 is alternately connected to a discharge port 11 and a suction port 12 provided on the valve plate 8 as the cylinder block l rotates (in FIG. Therefore, when this high pressure fluid is guiding the high pressure fluid on the discharge port 11 side into the cylinder 2 through the V notch 13, the cylinder 2
does not communicate with the suction port 12 side, and the cylinder 2
However, there was a problem in that the pressure rise inside the pump could not be slowed down sufficiently, and the reduction of the excitation force and noise was still insufficient.

Therefore, an object of the present invention is to make it possible to release high-pressure fluid introduced into the cylinder from the discharge port side near the bottom dead center to the suction port side by considering the positional relationship between the cylinder and the kidney port. Near the dead center, when the inside of the cylinder communicates with the suction port, it also communicates with the discharge port, making the pressure change inside the cylinder extremely gradual, reducing the excitation force and reducing noise. The purpose of the present invention is to provide a variable displacement pump that obtains the desired results.

<Means for Solving the Problems> In order to achieve the above object, the variable displacement pump of the first invention has nine cylinders 2 and kidney bows 1 and 7 which are rotatably driven by a shaft, or for simplicity, one ). A V-notch 13 extending from the discharge port 13 toward the bottom dead center BDP is provided on the valve plate 8, and high-pressure fluid is gradually introduced into the piston cylinder 2 through the V-notch 13 near the bottom dead center BDP when the suction stroke shifts to the discharge stroke. By guiding the pressure to the cylinder 2, pressure changes within the cylinder 2 are made gentler, the excitation force is reduced, and noise is reduced. Similarly, at the V-notch 14 near the top dead center TDP, high-pressure fluid is also gradually released to the suction port 12 side through the V-notch 14, thereby eliminating sudden pressure fluctuations in the cylinder 2 and reducing the excitation force. We are also trying to keep the noise low.

<Problems to be Solved by the Invention> However, in the conventional variable displacement pump described in item 1, the V-notch! 3.14 is provided to reduce the excitation force by gradually introducing high-pressure fluid into the cylinder through the V-notch 13 near the bottom dead center BDP. A slidably provided piston is reciprocated as the cylinder block rotates, and a kidney port communicating with the cylinder is connected to a suction port and a discharge port provided on the valve plate as the cylinder block rotates. In the variable displacement pump, the kidney port is eccentric to the trailing side (the opposite side in the direction of movement) with respect to the center of the cylinder, and the kidney port is placed under the piston. The present invention is characterized in that the kidney port is communicated with the suction port during the discharge stroke when the cylinder near the dead center communicates with the discharge port.

Further, the variable displacement pump of the second invention reciprocates a piston that is slidably provided in a cylinder of a cylinder block that is rotatably driven by a shaft, and reciprocates with the rotation of the cylinder block. In a variable displacement pump in which a kidney port communicating with a cylinder is communicated with a suction port and a discharge port provided on a valve plate as the cylinder block rotates, the kidney port is connected to a cylinder indicated by -1-. of the piston, eccentric to the trailing side with respect to the center of the piston.
The present invention is characterized in that the kidney port is communicated with the discharge port during the suction stroke in which the cylinder near the binary point communicates with the suction port.

Further, it is desirable to provide the valve plate (1) with a V-notch extending from at least one of the discharge port (6) or the suction port (13), located near the dead center (13), and communicating with the kidney port.

<Operation> In the first invention, in the discharge stroke near the bottom dead center of the piston, high-pressure fluid is guided into the cylinder from the discharge port side, but the kidney port eccentric to the cylinder center causes the high-pressure fluid to flow inside the cylinder. A portion of the fluid is discharged to the suction port side.

In this way, some of the fluid within the cylinder chamber is released to the suction port side, so that the pressure within the cylinder increases extremely slowly, reducing the excitation force and reducing noise.

Further, in the second invention, only the different parts of the kidney port and the cylinder will be explained for suction near the two-dimensional point.

As shown in FIG. 1, the kidney port 27 is installed in the cylinder block 2I with an eccentric amount e (J eccentricity) toward the trailing side with respect to the advancing direction of the cylinder block 2 shown by the arrow with respect to the center of the cylinder 2. The width of this kidney port 27 in the longitudinal direction is larger than the diameter of the cylinder 2 and extends to both sides of the cylinder 2.The state shown in FIG. 1 shows the state in which the piston 3 is at the bottom dead center BDP. and
The kidney port 27 directly communicates with the suction port 12,
It also communicates with the discharge port 11 through a V-notch I3. Therefore, near the bottom dead center BDT (see Fig. 6) when the piston 3 moves from the suction stroke to the discharge stroke, there is an inflow flow rate of Qin into the cylinder 2 through the V notch I3, and from the kidney bow 1-27 to the suction port I2. There is an outflow flow rate of Q out to Q out and a displacement volume of the piston 3 of dVs/dt. If the bulk elastic modulus of the fluid is 1, and the pressure inside the ring 2 is P, then at the stroke of the cylinder 2, the kidney bone 1 is eccentric to the trailing side through the center of the cylinder, so the cylinder At the time when the cylinder communicates with the suction port side, it communicates with the discharge port side through the kidney port, so the pressure within the cylinder decreases extremely slowly, the excitation force is reduced, and the noise is reduced.

In addition, when a notch is provided that extends from the discharge port or suction port near the dead center, this V notch gradually guides the high-pressure fluid from the discharge port into the cylinder.
Alternatively, the high-pressure fluid in the cylinder is gradually discharged to the suction port by the V-notch, and in addition to the effect of the eccentric kidney port described above, pressure changes in the cylinder are further moderated, and noise is reduced.

<Example> Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

This invention differs from the conventional example shown in FIGS. 5 and 67 only in the positional relationship between the cylinder and the kidney port, but otherwise has the same structure as the conventional example shown in -1-. The continuity formula of the field below is F
[Taking into account the contraction f1, the following equation (1) is obtained.

Here, as mentioned above, ■ ・Cylinder bore internal volume Qin ・Inflow flow rate Qout ・Outflow flow rate K ・Bulk elasticity coefficient P PressureAs is clear from this formula (1), the pressure change dP/dt in the cylinder 2 is calculated by the formula The presence of the outflow flow rate Qout in (1) makes it small. In other words, it becomes more gradual. Further, the inflow flow rate Qin is reduced by the throttling effect of the V-notch 13. In this way, the pressure change dP/dt
is the outflow flow ff1Qo due to the eccentricity of the kidney port 27.
Due to the existence of uL and the notch 13, the inflow flow rate Q
Since in itself is small, the increase in pressure by 1 can be made gradual. By the way, cylinder 2 is at bottom dead center B.
I) In the state where the fluid in the discharge port 11 is guided into the cylinder 2 through the notch 13 on the discharge side past II), the kidney port 27 communicates with the suction port 12 and all of the fluid in the cylinder 2 is introduced. suction port 12
By releasing the pressure to the side, the pressure inside the cylinder 2 rises more slowly. Experimental data on the change in pressure inside the cylinder 2 at this time is shown in FIG. 2 in comparison with the conventional example.

From FIG. 2, it can be seen that the pressure rise in this embodiment is much more gradual than in the conventional example shown in FIG. 5.6.

In addition, this variable displacement pump has a piston 2 shown in FIG.
Kidney port 2 in the vicinity of the two points T I) P
The leading side of the kidney port 27 is connected to the notch 14, and the trailing side of the kidney port 27 is connected to the discharge port 12.
As a result, the pressure within the cylinder 2 decreases gradually, the excitation force is reduced, and noise is reduced. This was proven from the experimental data shown in FIG. The pressure drop in the cylinder of this embodiment shown by the solid line in FIG. 3 is slower than that of the conventional example shown by the broken line.

<Effects of the Invention> As is clear from the above, according to the present invention, the kidney port is eccentrically moved toward the railing side with respect to the center of the cylinder, and the kidney port is sucked in during the discharge stroke near the bottom dead center of the piston. Even if the inside of the cylinder is connected to the discharge port, the inside of this cylinder is connected to the suction port side through the kidney port, so that a part of the fluid inside the cylinder can escape to the suction port side. Therefore, with the simple and inexpensive configuration of simply shifting the phase of the kidney port, the pressure rise inside the cylinder near bottom dead center becomes gradual, the excitation force is reduced, and noise can be significantly reduced. .

Further, according to the present invention, the kidney port is eccentric to the trailing side with respect to the center of the cylinder, and the kidney port is communicated with the discharge port during the suction stroke near the top dead center of the piston, so that the inside of the cylinder is connected to the suction port. Even if they are connected, high-pressure fluid is fed into the cylinder from the discharge port, so in this example, the V-notch 13 can be easily moved by simply shifting the phase of the kidney port.
14 (in addition to the J-loop, the kidney ports 27 extend to both sides of the cylinder 2 and are installed eccentrically toward the tray link side with respect to the center of the cylinder 2), so in addition to the effect of the notch, In the pressure transition region between the top dead center and the bottom dead center of the piston, the pressure in the cylinder rises and falls slowly, and the excitation force is significantly reduced, making it possible to significantly reduce noise. It is.

FIG. 4 shows another embodiment of the invention. In this cylinder block 31, the kidney port 37 is connected to the cylinder 2.
Eccentricity e('' set (J) on the trailing side with respect to the center of
ing. In Example 1 of Fig. 1, kidney
Ports 27 (extending on both sides of cylinder 2, but in this embodiment kidney ports 37 extend only on the trailing side of the cylinder) operate as in FIG.

Although FIG. 4 shows only one kidney port 37 and one cylinder 2 to simplify the drawing, there are actually nine of each.

With an inexpensive configuration, the pressure drop in the cylinder near the top dead center becomes gradual, the excitation force is reduced, and noise can be significantly reduced.

Further, according to the present invention, in addition to making the kidney port eccentric to the trailing side, the valve is provided with a notch that extends from at least one of the discharge port or the suction port and communicates with the kidney port near the dead center. Therefore, it has the function of gradually guiding high-pressure fluid into the cylinder from the discharge port through this hole, or gradually discharging the high-pressure fluid inside the cylinder to the suction port.
In addition to the eccentricity of the kidney port mentioned above, the increase or decrease in pressure inside the cylinder can be made more gradual, thereby reducing the excitation force and significantly reducing noise.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the main part of an embodiment of the present invention, FIGS. 2 and 3 are characteristic diagrams of the present invention and a conventional example showing pressure changes in the cylinder with respect to the rotation angle of the cylinder block, and FIG. 4 5 is a cross-sectional view of a shilling block according to another embodiment of the present invention, FIG.
Figure (J: Front view of conventional Hartz plate, Figure 7 (j: Cross-sectional view of the conventional variable displacement pump), 127 cylinder, 3 screws, 8 Hartz plate, 11 discharge. Port, 12 Suction port, +3.I,!, -V nonoji, 2131 Knolling block, 27 Kidney bow 1.

Claims (3)

[Claims] (1) A piston (3) slidably provided in a cylinder of a cylinder block rotationally driven by a shaft is caused to reciprocate as the cylinder block rotates, and communicates with the cylinder (2). Kidney port (2)
7, 37) are connected to a suction port (12) and a discharge port (11) provided in a valve plate (8) as the cylinder block rotates, the kidney Ports (27, 37) are connected to the above cylinder (2).
), and the cylinder near the bottom dead center of the piston (3) is eccentric to the trailing side with respect to the center of the discharge port (1
1) A variable displacement pump characterized in that the kidney ports (27, 37) are communicated with the suction port (12) during the discharge stroke communicating with the pump. (2) A piston (3) slidably provided in a cylinder of a cylinder block rotationally driven by a shaft is caused to reciprocate as the cylinder block rotates, and communicates with the cylinder (2). Kidney port (2)
7, 37) are connected to a suction port (12) and a discharge port (11) provided in a valve plate (8) as the cylinder block rotates, the kidney Ports (27, 37) are connected to the above cylinder (2).
) in the suction stroke in which the cylinder (2) near the top dead center of the piston (3) communicates with the suction port (12), the kidney port (27, 37) A variable displacement pump characterized in that the pump is configured to communicate with a discharge port (11). (3) In the variable displacement pump according to claim 1 or 2, the discharge port (
11) or the suction port (12), and extends from at least one of the kidney ports (27, 37) near the dead center.
A variable displacement pump equipped with V-notches (13, 14) that communicate with the