JPH0686869B2 - Axial piston pump - Google Patents

Description

The present invention relates to a swash plate type axial piston pump.

[Prior Art] An example of a conventional swash plate type axial piston pump
As shown in the longitudinal sectional view of the drawing, reference numeral 1 denotes a cylinder block, which has a plurality of cylinders 2 on the same circumference, and a piston 3 reciprocates in the cylinder 2, and an end surface 4 of the cylinder block is a valve plate. 5 is facing and in contact. The cylinder block 1 rotates integrally with the shaft 7 by means of a spline 6 or a key, but it can move independently in the axial direction. The head of the piston 3 that reciprocates in the cylinder 2 has a slipper 8. Is constantly pushed by the spring to the swash plate 9, and the shaft 7
Supported by 10, 11.

In such a device, when the shaft 7 is rotated around the axis, the cylinder block 1 and the piston 3 also rotate together with the shaft 7, and at that time, the piston 3 is slidingly engaged with the slipper 8, and the slipper 8 is the swash plate 9. As the cylinder block 1 rotates, the piston 3 reciprocates in the cylinder 2 because it slides up.

The axial piston pump uses the movement of the piston 3 to suck the low-pressure working fluid and discharge it to the high-pressure side. On the contrary, the inflow of the high-pressure working fluid causes the piston and the cylinder block to rotate. A motor that outputs rotational torque to the spindle is used very much.

FIG. 3 is a front view of the valve plate 5 for sucking and discharging the fluid. In FIG. 3, 12 is a suction port, 13 is a discharge port, 14 is a cylinder port of the cylinder block 1, and 15 is a conduit. It is connected to the discharge port 13, 16 is the top dead center, 17 is the bottom dead center, and the suction port 12 and the discharge port 13 are respectively the suction port 18 and the discharge port of the pump main body as shown in FIG. It communicates with 19.

FIG. 4 is a development view showing the relationship between the cylinder port 14, the discharge port 13 of the valve plate 5, and the conduit 15. In FIG. 4 (a), the cylinder block 1 rotates in the direction of arrow R and the piston 3 sucks. Near the bottom dead center (hereinafter referred to as BDC) 2a of the so-called piston 3 that shifts from the stroke to the discharge stroke
3 shows the relationship between the cylinder port 14 and the suction port 12 and the discharge port 13 of the valve plate 5, and the valve plate 5 is provided with a conduit 15.

During the cylinder rotation angle θ ₀ until the piston 15 moves from the suction stroke to the discharge stroke near the BDC and the cylinder port 14 opens to the discharge port 13, the suction pressure Pc in the cylinder 2 is increased in the suction port 12. In order to smoothly change the suction pressure P _L from the suction pressure P _L to the pressure P _H in the discharge port 13, an appropriate amount of high-pressure fluid in the discharge port 13 is introduced into the cylinder 2.

FIG. 4 (b) shows a change situation of the internal pressure Pc of the cylinder 2 near BDC, and FIG. 4 (c) shows a change situation of the discharge flow rate q from the cylinder 2 near the same BDC to the discharge port 13 per unit time. .

A curve A in FIG. 3C shows the relationship between the rotation angle θ of the cylinder block 1 and the geometrical discharge flow rate q from the cylinder 2 to the discharge port 13, but the actual discharge amount depends on the compressibility of the working fluid. Therefore, it changes like the curve B.

Explaining this phenomenon at the time of cylinder rotation angle θ = θ ^* , the geometric discharge amount is q ₁ ^* , while the cylinder internal pressure is Pc ^* and has not yet reached the discharge pressure P _H. The q ₂ ^* flows back from the discharge port 13 through the conduit 15 into the cylinder 2 to compress and pressurize the working fluid in the cylinder 2. Such a deviation between the geometric discharge amount and the actual discharge amount continues until the cylinder 2 internal pressure Pc becomes equal to the discharge pressure P _H.

The above is a description of one piston, but the average value of the geometric discharge flow rate when the number of pistons is large to some extent ▲
It is well known that the ratio of the variable flow rate Δq to ▼ is about 2.5% when the number of pistons is 7, about 1.5% when the number of pistons is 9, and about 1.0% when the number of pistons is 11.

On the other hand, the difference between the actual discharge amount (curve B) and the geometric discharge flow rate (curve A) increases as the discharge pressure P _H increases. Therefore, the fluctuation of the actual discharge flow rate is much larger than the above-mentioned geometrical relationship, and this fluctuation of the flow rate induces a pressure fluctuation in the working fluid in the high pressure system (not shown) communicating with the discharge port 13 and causes noise. This causes problems such as an increase and a loss of stability of a load system using the working fluid.

[Problems to be solved by the invention]

The present invention has been proposed in view of such circumstances,
The time fluctuation of the discharge amount of the working fluid becomes small, and as a result, the pressure fluctuation of the discharge fluid becomes small, the piping vibration and the pulsating noise are reduced, and the working fluid having a stable pressure can be discharged to the load system. It is an object to provide a shear piston pump.

[Means for solving problems]

To this end, the present invention is designed so that a swash plate causes a piston to reciprocate in a plurality of axial cylinders bored in a cylinder block that comes into contact with a valve plate having an intake port and a discharge port and engages with a shaft to rotate. In the axial piston pump configured as described above, a throttle and a pressure accumulator are inserted in series in a conduit opening in the sliding surface between the suction port and the discharge port in the vicinity of the bottom dead center of the valve plate. It is characterized in that the fluid in the fluid line is supplied to the same pressure accumulator through the same throttle.

[Work]

In the present invention, the low-pressure working fluid sucked from the suction port in the suction stroke into the cylinder, until the cylinder is opened to the discharge port, the high-pressure fluid in the pressure accumulator flowing through the conduit to the vicinity of the discharge pressure, Can be compressed and pressurized with the desired pressure gradient.

〔Example〕

An embodiment of the present invention will be described with reference to the drawings. FIG. 1A is a development view of the structure, and FIGS. 1B and 1C are diagrams showing the operation.

In FIG. 2A, the same symbols as in FIGS. 2 to 4 indicate the same members as those in FIG. 2, and a pressure accumulator 22 is connected to a high pressure piping system 20 communicating with the discharge port 19 via a throttle valve 21. Then, a conduit 15 that opens on the sliding surface between the suction port 12 and the discharge port 13 near the BDC of the valve plate 5 communicates with the outlet of the pressure accumulator 22.

In such a device, the high pressure working fluid is always stored in the pressure accumulator 22, and if the pressure P _A in the pressure accumulator 22 is higher than the internal pressure Pc of the cylinder 2a, the working fluid is transferred from the pressure accumulator 22 to the cylinder 2a. The pressure in the cylinder 2a rises. However, it is assumed that the pressure accumulator 22 has a capacity such that the fluctuation of the internal pressure P _A during this period is not so large. Therefore accumulator
The fluid flowing from 22 into the cylinder 2a is a high pressure piping system.
The pressure is replenished into the pressure accumulator 22 from the high-pressure piping system 20 via the throttle valve 21 within a range in which the flow rate does not change significantly.

As a result, by appropriately selecting the opening area and timing of the conduit 15 with respect to the cylinder port 14, by the time the cylinder port 14 opens to the discharge port 13 of the valve plate 5, the pressure Pc in the cylinder 2a is close to the discharge pressure P _H. It can be pressed smoothly.

Then, the cylinder 2 near the BDC shown in Fig. 1 (b)
a Change in internal pressure Pc and cylinder 2 shown in Fig. 1 (c)
The change situation of the discharge flow rate q from a to the discharge port 13 is
Unlike the conventional case shown in the figure, since there is no above-mentioned backflow q ₂ ^* from the discharge port 13 to the cylinder 2a at the beginning of the discharge stroke, the discharge flow rate in this case is as shown by the curve C in FIG. 1 (c). The amount of change in the discharge flow rate from the geometrical discharge amount A is reduced by q ₂ ^* .

Therefore, as a result, the pressure fluctuation of the discharged fluid is reduced, the pipe vibration and the pulsating noise are reduced, and the working fluid having a stable pressure can be supplied to the load system.

In the above-mentioned embodiment, the case where the high-pressure working fluid to the pressure accumulator 22 is supplied from the high-pressure piping system 20 has been shown, but the working fluid of the separately placed pressure pump may be used.

〔The invention's effect〕

In short, according to the present invention, the piston is reciprocated by the swash plate in a plurality of axial cylinders bored in the cylinder block which is in contact with the valve plate having the intake port and the discharge port and engages with the shaft to rotate. In the axial piston pump that is made to move, a throttle and a pressure accumulator are inserted in series in a conduit that opens on the sliding surface between the suction port and the discharge port near the bottom dead center of the valve plate, By supplying the fluid of the high-pressure fluid line to the same pressure accumulator through the same throttle, the time fluctuation of the working fluid discharge amount becomes small, and as a result, the pressure fluctuation of the discharge fluid becomes small and the pipe vibration and pulsation noise The present invention provides an axial piston pump capable of discharging a working fluid having a stable pressure with respect to a load system. Therefore, the present invention is extremely useful industrially. A.

[Brief description of drawings]

FIG. 1 shows an embodiment of the axial piston pump of the present invention. FIG. 1 (a) is a development view of the structure, FIG. 1 (b),
(C) is a diagram showing an operation. FIG. 2 is a vertical sectional view of a known axial piston pump,
FIG. 3 is a front view of the above valve plate, FIG. 4 is an explanatory view of the operation of the above valve plate, FIG. 3 (a) is a development view of the structure, and FIG. 3 (b) and FIG. It is a diagram. 1 …… Cylinder block, 2a …… Cylinder, 3 ……
Piston, 4 …… Cylinder block end face, 5 …… Valve plate, 6 …… Spline, 7 …… Shaft, 8 …… Slipper, 9 …… Swash plate, 10,11 …… Bearing, 12 …… Suction port, 13 …… Discharge port, 14 …… Cylinder port, 15…
… Conduit, 16 …… top dead center, 17 …… bottom dead center, 18 …… suction port, 19 …… discharging port, 20 …… high pressure piping system, 21 …… throttle valve, 22 …… accumulator.

Front page continued (72) Inventor Kiyoji Morita 6-16-1 Hikoshima Enoura-cho, Shimonoseki City, Yamaguchi Prefecture Mitsubishi Heavy Industries, Ltd. Shimonoseki Shipyard (72) Inventor Shiro Takayama 6-16-1 Hinoshima-enoura-cho, Shimonoseki City, Yamaguchi Prefecture No. Mitsubishi Heavy Industries Ltd. Shimonoseki Shipyard (56) References Japanese Patent Publication No. 43-1073 (JP, B1) Actual Publication No. 61-28060 (JP, Y2)

Claims (1)

[Claims] 1. A swash plate causes a piston to reciprocate in a plurality of axial cylinders bored in a cylinder block which is in contact with a valve plate having an intake port and a discharge port and engages with a shaft to rotate. In the axial piston pump configured as described above, a throttle and a pressure accumulator are inserted in series in a conduit opening in the sliding surface between the suction port and the discharge port near the bottom dead center of the valve plate, and high pressure fluid An axial piston pump characterized in that the fluid in the line is supplied to the pressure accumulator through the same throttle.