JPS5843589B2 - axial plunger pump - Google Patents

Description

[Detailed description of the invention] The present invention relates to an axial plunger pump.

In general, there are two types of axial plunger pumps: oblique shaft type and swash plate type, and these types include constant discharge rate type and variable discharge rate type, respectively.

In each of these pumps, when moving from the suction side to the discharge side, a large amount of noise is generated due to the pressure difference between the suction port and the discharge port, which is not only unpleasant but also poses a pollution problem.

For this reason, one of the noise countermeasures for these pumps is to improve the valve plate.

That is, methods include installing a preload band, a pressure reduction band, and an oil guide groove.

The installation of a precompression zone is a method in which a positive overlapping zone is provided between the suction port and the discharge port, and the pressure inside the cylinder is precompressed until it becomes equal to the discharge pressure before being discharged.

The vacuum zone is an overlapping zone between the discharge port and the suction port, and its purpose is to match the pressure within the cylinder with the pressure at the discharge (suction) port.

According to this method, a significant reduction in noise can be seen at a certain discharge pressure and angle of inclination of the swash plate (slanted shaft), but as the pressure goes beyond that point, the noise actually increases.

Furthermore, the installation of oil guide grooves is a method of converting the above-mentioned positive polymerization into negative polymerization using narrow grooves.

With this method, the range of noise reduction can be expanded compared to the above method, but there is a limit to the range when considering volumetric efficiency and the like.

Furthermore, some axial plunger pumps have a rotating swash plate type in the pond.

In this type, since the cylinder block is fixed, a valve plate is not required, and a check valve is used instead.

For this reason, the pressure inside the cylinder is always discharged (inhaled).
Since the check valve opens only when the pressure is almost the same as the pressure, the noise level is lower than that of the above-mentioned type.

However, with this type, it is generally mechanically troublesome to use a variable capacity type, and often causes an increase in noise.

In addition, each of the above-mentioned pumps does not have good self-priming performance by itself.

The reason is that the port area of the first two is limited;
Another advantage of the latter is that it uses a chinic valve for inhalation.

Regarding the first two cases, a method using a fixed displacement auxiliary pump is sometimes taken as a solution, but in this case, it is necessary to release the excess flow through a low-pressure IJ pump, resulting in power loss and noise generation. Therefore, an object of the present invention is to provide an axial plunger pump that is noiseless and has good self-priming performance in order to solve the above-mentioned conventional drawbacks.

To achieve this object, the present invention is characterized in that the cylinder block is provided with a discharge check valve and a long hole facing in the direction of inclination.

That is, the axial plunger pump according to the present invention incorporates a discharge check valve, which is a characteristic of a rotating swash plate type, into a rotating cylinder block, and discharges after the pressure inside the cylinder becomes equal to the discharge pressure, thereby preventing noise. In order to reduce this and increase the self-priming performance, a slanted long hole provided in the cylinder block is used as a centrifugal pump.

Furthermore, the present invention eliminates the need for a low-pressure IJ, and furthermore, by using a timing port type suction port, it is possible to apply suction pre-pressure. For example, when the cylinder moves from discharge to suction, the pressure inside the cylinder Even if the change is sudden, the centrifugal pump can dampen the vibrations from being transmitted to the suction pipe system.

Next, an example of implementation of the present invention will be described with reference to the drawings.

First, the outline will be explained.

Due to the automatic change of the precompression stroke by the discharge check valve 24, which is the gist of the present invention, the tilting moment of the swash plate 12 becomes larger than that of a general one.

Therefore, it is necessary to increase the operating force of the servo, and the main discharge pressure is reduced by the pressure reducing valve 7 and used for the servo.

Here, when the load is small, a servo auxiliary pump 5 is used.

When the load is large, the auxiliary pump 5 is unloaded by an unload valve to prevent power loss.

Between the cylinder block 17 and port block 3,
A valve plate 32 similar to conventional pumps is included, and this is to prevent tilting moment from occurring in the cylinder block 17 by switching the pressure in the downstream chamber of the check valve.

Compared to conventional valve plates 32, this valve plate 32 does not require consideration of a confinement section, etc., because the volume of the downstream chamber of the check valve remains constant even when the cylinder block rotates. This is because the pressure change occurs only when communicating with the port, and even if the pressure change at this time is large, since the volume is small, it will have little effect on the whole.

In addition, to prevent this tilting moment, the discharge check valve 2
4 is provided coaxially with the piston 19.

The suction port 28 is provided in the thrust plate 20 that makes sliding contact with the shoe 21 at the bottom of the piston.

This thrust plate is open only on the suction stroke side and communicates with a hole on the back side of the swash plate.

On the discharge stroke side, a special thrust bearing is not required because the force of the hydraulic balance is received by the pressure chamber on the back side of the shoe.

Next, the structure and operation will be explained in detail.

A cover 2 is fixed to one end of the body 1, a port block 3 is fixed to the other end of the body 1 via bolts 4, and an auxiliary servo pump 5 is connected to the end of the port block 3.

A servo block 6 containing a servo mechanism, a valve block 9 containing a pressure reducing valve 7 and a shuttle valve 8 are connected above the body 1.

An input shaft 10 rotatably disposed in the center shaft of the body 1 passes through the cover 2 and is rotatably supported by the port block 3 and the center shaft of the auxiliary pump 5.

The interior 11 of the body 1 is hollow, and a swash plate 12 is inserted into the interior 11 so as to be able to freely change the tilt angle.
3 to a connecting member 14, and the connecting member 14 is connected to a servo piston 15 and a link 16 provided in the servo block 6, so that the inclination angle is changed by movement of the servo piston 15.

A cylinder block 17 that rotates together with the input shaft 10 inside the body 1 is attached to the swash plate 1 on the outer periphery of the input shaft 10.
A plurality of cylinders 18 are formed in the axial direction in the cylinder block 17, and a hollow piston 19 is slidably inserted into the cylinder 18. It is connected to a hollow shoe 21, and the suction roll end of the shoe 21 comes into sliding contact with the side surface of a thrust plate 20 fixed to the inside of the swash plate 12.

A check valve 24 is provided at the discharge part of the cylinder 18 so as to be openable and closable.This valve 24 is made up of a check ball 24 pressed against a check seat 22 by a spring 23. It is designed to be discharged to a discharge port through a hole 25 bored in 17.

The interior 26 of the cylinder block 17 is hollow, and the interior is connected to a suction port, which will be described later.

Further, a long hole 27 is bored diagonally in the cylinder block 17, and the long hole 27 communicates the inside 26 of the cylinder block with the inside 11 of the body 1, so that when the cylinder block 17 rotates, the inside 26 of the cylinder block is operated by centrifugal force. Oil is spouted into the inside 11 of the body 1.

Therefore, the elongated hole 27 functions as a centrifugal pump and improves self-priming performance.

The thrust plate 20 has a semicircular suction port 2 on one side.
8 is bored, and the suction port 28 communicates with a suction hole 29 provided in the swash plate 12, and these suction holes 29 and the suction port 28
Hydraulic oil inside the body 11 is sucked into the cylinder 18 from the inside of the shoe 21 and the piston 19 during the suction stroke, and on the discharge side, the eye end of the shoe 21 is separated from the suction port 28 and comes into sliding contact with the side surface of the thrust plate 20. It has become.

(Figures 1 and 2) Next, the port block 3 is provided with an inlet port 30 and a discharge port 31 as shown in Figures 3 and 4.
The inlet 30 opens directly into the cylinder block interior 26.

A valve plate 32 is fixed between the port block 3 and the cylinder block 17, and the cylinder block 17 comes into sliding contact with the left side surface of the valve plate 32.

There are holes 33, 34° 35.36 at the top of the port block 3.
The hole 33 communicates with the discharge port 31 and the hole 34 communicates with the suction port 30, which communicate with the annular groove 58 of the valve block 9 and the liquid chamber 54, respectively.

The hole 35 is for guiding oil from the discharge port 38 of the auxiliary pump 5 to the shuttle valve 8, and the hole 36 is for guiding oil from the discharge port 38 of the auxiliary pump 5 to the shuttle valve 8.
The secondary pressure is communicated to a pilot circuit 43 of an unload relief valve 41 built into the auxiliary pump 5.

The auxiliary pump 5 has a suction port 37 and a discharge port 38, through which the oil from the suction port 37 is discharged to a discharge port 38, which communicates with the shuttle valve 8.

Also, the holes 39 and 40 are the valve holes 42 of the unload relief valve 41.
It leads to both ends.

Next, the shuttle valve 8, as shown in FIG. 8, consists of two double check valves 48a and 48b.

That is, there are four passages a and b in the valve block 9. c and d are bored, and springs 47a and 47 are installed in the two passages a and b.
At b, the check valves 48a and 48b are pressed against the valve seats.

The passage a communicates with the hole 35 of the port block 3, and the passage of the pond communicates with the hole 36 of the port block 3, and each passage a, b has a hole e in the annular groove 58 of the pressure reducing valve 7 shown in FIG. They are connected through each other.

Further, the passage C communicates with the hole 34 of the port block 3 and the liquid chamber 54 of the pressure reducing valve 7, and the passage d communicates the hole 36 of the port block 3 with the liquid chamber 55 of the pressure reducing valve 7.

The pressure reducing valve 7 has a valve hole 51 in the valve block 9, as shown in FIG. 54
, 55, the liquid chamber 54 communicates with the tank side, and the liquid chamber 55
communicates with the hole d of the shuttle valve 8.

In addition, through holes 56 and 57 are bored in the spool 52 in the radial direction, and the through hole 56 communicates with an annular groove 58 of the valve hole 51, and the annular groove 58 is supplied with oil discharged from the cylinder 18. It looks like this.

As shown in FIG. 1, the servo mechanism has a feedback spool 60 slidably inserted into the valve hole 59.
A manual spool 61 is slidably inserted inside.
Feedback spool 60 is connected to link 16 via pin 62.

An annular groove 63 , 64 is formed in the valve hole 59 , and an annular groove 63 , 64 is formed in the valve hole 59 .
communicates with the left liquid chamber 65 of the piston 15, and the annular groove 64 communicates with the right liquid chamber 66, such that the high pressure from the shuttle valve 8 is introduced into the liquid chamber 65 or 66 via these annular grooves 63,64. It has become.

Next, we will discuss the operation.

First, I will explain along the flow of oil.

Oil entering from the suction port 30 is guided into the gap between the rotating cylinder block 11 and the drive shaft 10, that is, into the cylinder block interior 26.

Next, the oil is guided into the interior 11 of the body 1 under dynamic pressure by a centrifugal pump constituted by a plurality of long holes 27 opened radially between each cylinder 18 of the cylinder block 17 .

The oil led into the interior 11 of the body 1 passes through a suction hole 29 formed on the input shaft side of the swash plate 12, which can be tilted under pre-pressure, and a suction port 28 of the thrust plate 20, which also serves as a timing port, to the shoe 21. ．． It enters the cylinder 18 through a hole in the piston 19.

As the cylinder block 17 rotates and the piston 19 enters the discharge stroke, the suction port 28 of the thrust plate 20 is closed and the oil in the cylinder 18 begins to increase in pressure.

At this time, the downstream chamber of the check valve 24 is in communication with the discharge port 31, so the check valve 24 is closed.

When the pressure inside the cylinder 18 increases and becomes slightly higher than the load pressure, the discharge check valve 24 opens and the oil is discharged.

During this time, the cylinder pressure increases smoothly.

When the discharge stroke ends, the pressure inside the cylinder decreases, the check valve 24 closes, and the suction port 28 of the thrust plate 20 closes.
opens, the pressure in the downstream chamber of the check valve 24 is relieved, and the suction stroke begins.

Next, the operation of the servo regulator will be explained. When the load is small and the pressure necessary to drive the servo cannot be obtained, the servo regulator is driven by the auxiliary pump 5 for the servo.

Its operating pressure is set by an internally built relief valve 41.

When the load increases, the servo is driven using its discharge pressure.

However, the maximum pressure is set by the pressure reducing valve 7.

The shuttle valve 8 determines whether the auxiliary servo pump 5 or the main discharge pressure is used.

When the load is large and there is no need to use the auxiliary pump 5, the main discharge pressure that has passed through the pressure reducing valve 7 is guided to the relief valve 41 mentioned above as a pilot pressure, and the auxiliary pump 5 is unloaded to reduce power loss. do.

The above valves and auxiliary pump are installed at the rear of the pump body.

Therefore, only one piping to the servo is required.

The effects obtained by the present invention are as follows.

Although it is a self-priming type, since the elongated hole 27 is incorporated as a centrifugal pump, the self-priming limit is high.

Further, by providing the discharge check valve 24, noise can be reduced and the discharge amount can be varied.

Since the servo uses high voltage, it also has the effect of being able to be made smaller overall.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view of an axial plunger pump according to an embodiment of the present invention. FIG. 2 is a front view of the swash plate and thrust plate. FIG. 3 is a longitudinal side view of the port block. FIG. 4 is a rear view of the valve plate. FIG. 5 is a rear view of the port block. FIG. 6 is a vertical rear view of the auxiliary pump taken along the line ■-■ in FIG. 1. FIG. 7 is an enlarged partially cutaway view of FIG. 6. FIG. 8 is a vertical cross-sectional view taken along the line ■--■ in FIG. 1 of the shuttle valve. FIG. 9 is a vertical cross-sectional view taken along the line ■--■ in FIG. 1 of the pressure reducing valve. FIG. 10 is a hydraulic circuit diagram.

Claims (1)

[Claims] 1 A hollow cylinder block that is integral with the input shaft is rotatably provided inside the body, and a swash plate that can freely change the tilt angle is provided opposite the cylinder block inside the body. The thrust plate is fixed,
A semicircular suction port is bored on one side of the thrust plate, and this suction port communicates with the inside of the body through a suction hole provided in the swash plate.Multiple cylinders are formed in the cylinder block in the axial direction. A hollow piston is slidably inserted into the cylinder, the piston is connected to a hollow shoe, and the suction port end of the shoe slides on the side surface of the thrust plate to open and close the suction port, and the cylinder A check valve is provided in the discharge part of the cylinder block, and opening and closing of the check valve opens and closes the discharge part of the cylinder to the discharge port.Furthermore, the inside of the cylinder block communicates with the suction port, and the cylinder block is bored in a radial direction. An axial plunger pump that communicates with the inside of the body through a slotted hole.