JPH0552263U - Radial piston pump - Google Patents

Abstract

(57) [Summary] [Purpose] To increase the maximum flow rate without increasing the pump size. [Configuration] Drive shaft 1 that is rotated by the driving force of an engine or the like
An eccentric cam 2 is provided at the center of the. A suction chamber 5 communicating with the suction passage 4 is formed in a portion of the pump body 3 in which the eccentric cam 2 is housed, and a plurality of cylinders 6 are formed in the equiangular radial direction from the suction chamber 5. A piston 7 is arranged in the cylinder 6, and a piston port 9 that connects the suction chamber 5 and the cylinder chamber 8 is formed on a side surface of the piston 7 at a position where the piston port 9 opens to the suction chamber 5 as the piston 7 reciprocates. Is formed in. A suction passage 16 that connects the suction chamber 5 and the cylinder chamber 8 is provided in the pump body 3,
When the piston port 9 opens and closes with respect to the suction chamber, it is configured to open and close at the same time depending on whether or not the suction passage opening 16a is covered by the side surface of the piston.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 This invention relates to a radial piston pump.

[0002]

[Prior Art]

 Examples of conventional radial piston pumps include those shown in FIGS. 6 to 7 (see, for example, JP-A-58-15770 and JP-A-62-105371).

That is, the eccentric cam 2 is provided in the central portion of the drive shaft 1 that is rotated by the driving force of the engine or the like. In the pump body 3, a suction chamber 5 communicating with the suction passage 4 is formed in a portion in which the eccentric cam 2 is housed, and a plurality of cylinders 6 are formed in the equiangular radial direction from the suction chamber 5.

A piston 7 is disposed in the cylinder 6, and a side wall of the piston 7 is provided with a piston port 9 for communicating the suction chamber 5 and the cylinder chamber 8 with each other as the piston 7 reciprocates. It is formed in a position that opens with respect to.

Further, a discharge port 11 that connects the cylinder chamber 8 and the fluid discharge passage 10 is formed on the side wall of the cylinder chamber 8, and the pressurized fluid discharged from each cylinder chamber 8 through the discharge port 11 is , Is discharged from the outlet port 12. The discharge flow characteristic with respect to the rotation speed is such that the flow rate is discharged in proportion to the displacement volume per rotation up to a certain rotation speed, and at a certain rotation speed or more, a substantially constant flow rate is discharged due to the saturated flow rate characteristic. Has become.

A region above a certain number of rotations is called a limit region, and a region below a certain number of rotations is called an eigenregion.

[0007]

[Problems to be solved by the device]

 However, in such a conventional radial piston pump, if it is desired to widen the proper range and increase the maximum flow rate, lower the piston port position or increase the opening area such as widening the port diameter. Although there are methods, there is a problem that these methods lead to an increase in the size of the piston and an increase in the size of the pump.

The present invention has been made in view of such conventional problems, and provides a radial piston pump capable of expanding the proper range and increasing the maximum flow rate without increasing the pump size. The purpose is to do.

[0009]

[Means for Solving the Problems]

 Therefore, according to the present invention, the piston in the cylinder is reciprocally moved by the eccentric cam rotated by the pump driving force, and the piston port opened on the side surface of the piston moves from the suction chamber to the fluid in the piston stroke region opened to the suction chamber. In a radial piston pump that pressurizes and discharges the fluid that has flowed into the cylinder chamber in the piston stroke region where the piston port closes the suction chamber, the suction passage that connects the suction chamber and the cylinder chamber is provided. The opening provided in the pump body on the cylinder side wall of the suction passage is opened and closed at the same time when the piston port is opened and closed.

[0010]

[Action]

 Simultaneously with opening and closing of the piston port that opens on the side of the piston, a separate suction passage is also opened and closed to suck fluid from the suction chamber into the cylinder chamber.

Therefore, the same effect as when the opening area of the piston port is increased is obtained, and the suction of the fluid is sufficiently performed up to higher rotation, so that the eigen region is widened and the maximum flow rate is increased.

[0012]

【Example】

 Hereinafter, the present invention will be described with reference to the drawings. 1 and 2 are views showing an embodiment of the present invention.

First, the configuration will be described. The same components as those of the related art are designated by the same reference numerals, and detailed description thereof will be omitted.

The piston 7 is pressed against the eccentric cam 2 by a spring 15 and reciprocates in the fixed cylinder 6 of the pump body 3 by the rotation of the eccentric cam 2.

A suction passage 16 that is opened and closed simultaneously when the piston port 9 is opened and closed with respect to the suction chamber 5 is provided in the pump body 3 by opening an opening 16a in the side wall of the cylinder 6 near the piston end 7a. ing. In addition, 13 is a plunger cap, 14 is a retainer, and 18 is a discharge check valve.

Next, the operation will be described. The piston 7 is pressed against the eccentric cam 2 by the spring 15 and reciprocates in the cylinder 6 as the eccentric cam 2 rotates.

In the piston stroke region where the piston 7 approaches the rotation center of the eccentric cam 2 and the suction chamber 5 and the cylinder chamber 8 communicate with each other through the piston port 9 and the suction passage 16, the piston 7 moves from the top dead center to the bottom dead center. During the movement, cavitation occurs in the cylinder chamber 8 due to a sudden pressure drop, and the pressure is almost constant.

Further, the flow rate of the fluid sucked into the cylinder chamber 8 through the piston port 9 and the suction passage 16 depends on the differential pressure between the negative pressure in the cylinder chamber 8 and the pressure in the suction chamber 5, and the piston port 9 And the total cross-sectional area of the opening 16a of the suction passage 16.

By the way, since the differential pressure between the negative pressure in the cylinder chamber 8 and the pressure in the suction chamber 5 is substantially constant in the piston stroke region, the flow rate sucked into the cylinder chamber 8 is the piston port 9 Is approximately proportional to the total opening area of the suction passage 16 and the opening 16a of the suction passage 16.

While the pump driving speed is low, while the suction chamber 5 and the cylinder chamber 8 are in communication with each other by the piston port 9 and the suction passage 16, while the piston 7 is present in the piston region, The inside of 8 is filled with the suction fluid, and the cavitation disappears.

Therefore, the compression of the fluid is started by the movement of the piston 7 from the bottom dead center to the top dead center, and the pressure of the cylinder chamber 8 increases as the opening areas of the piston port 9 and the suction passage opening 16a decrease. After the piston port 9 is closed by the side wall of the cylinder 6 and the suction passage opening 16a is closed by the side surface of the piston 7, the pressure in the cylinder chamber 8 rises sharply and becomes equal to or higher than the working pressure of the discharge check valve 18. The discharge check valve 18 opens, and the fluid that has passed through the fluid discharge passage 10 and the discharge port 11 is discharged from the outlet port 12.

As the driving speed of the pump increases, the opening time of the piston port 9 to the suction chamber 5 and the opening time of the opening 16 a of the suction passage 16 to the cylinder chamber 8, that is, the suction chamber 5 and the cylinder. The communication time with the room 8 becomes shorter.

For this reason, the fluid cannot be sufficiently sucked within the opening time. Therefore, when the driving rotation speed of the pump is higher than a certain rotation speed, even if the piston port 9 and the suction passage opening portion 16a are completely closed, the inside of the cylinder chamber 8 is closed. The cavitations of will not disappear and will remain, and the discharge flow rate per piston stroke will be within the restricted range.

Here, conventionally, since the fluid is sucked from the suction chamber 5 to the cylinder chamber 8 only by the piston port 9, the total suction cross-sectional area is small. Therefore, as indicated by the solid line in FIG. 3, the pump drive rotation speed falls within the limit range at a low rotation speed N ₁ .

On the other hand, according to this embodiment, the suction passage 16 connecting the suction chamber 5 and the cylinder chamber 8 is separately provided, and the piston port 9 opens and closes with respect to the suction chamber 5 and at the same time, the suction passage 16 Since the opening / closing portion 16a is opened / closed depending on whether or not it is covered by the side surface of the reciprocating piston 7, the total cross-sectional area that connects the suction chamber 5 and the cylinder chamber 8 can be changed without changing the size of the piston 7. The same effect can be obtained as when the piston port 9 is enlarged and the opening area of the piston port 9 is increased. Therefore, the suction of the fluid is sufficiently performed up to the higher rotation.

As a result, as shown by the dotted line in FIG. 3, the eigen region is widened and the maximum flow rate is increased, and the limit region is entered at a high rotation speed N ₂ .

4 and 5 show another embodiment of the present invention. In this embodiment, an annular groove 17 which is elongated in the circumferential direction is formed in the wall surface of the cylinder 6 on the piston end 7a side of the intake passage 16 to form an opening.

According to this embodiment, even if the total cross-sectional area of the suction passages is not increased by increasing the number of suction passages 16, the opening (annular groove 17) of the suction passage 16 is effectively moved in the circumferential direction of the piston 7. Since it spreads, it is possible to increase the flow rate sucked into the cylinder chamber 8 through the suction passage 16 as compared with the one embodiment.

[0029]

[Effect of the device]

 As described above, according to the present invention, the eigenvalue can be expanded and the maximum flow rate can be increased.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing an essential part of the same embodiment.

FIG. 3 is a diagram showing a flow rate characteristic of the same embodiment.

FIG. 4 is a sectional view showing another embodiment of the present invention.

FIG. 5 is a sectional view showing a main part of another embodiment of the present invention.

FIG. 6 is a sectional view showing a conventional example.

FIG. 7 is a sectional view showing an essential part of a conventional example.

[Explanation of symbols]

 2 ... Eccentric cam 3 ... Pump body 5 ... Suction chamber 6 ... Cylinder 7 ... Piston 8 ... Cylinder chamber 9 ... Piston port 15 ... Spring 16 ... Suction passage 16a ... Suction passage opening 17 ... Annular groove

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. An eccentric cam rotated by a pump driving force causes a piston in the cylinder to reciprocate, so that a piston port opened on a side surface of the piston moves a fluid from the suction chamber to a piston stroke region in the piston stroke region. In a radial piston pump that sucks into the chamber and pressurizes and discharges the fluid that has flowed into the cylinder chamber in the piston stroke region where the piston port closes to the suction chamber, a suction passage that connects the suction chamber and the cylinder chamber is provided in the pump body. A radial piston pump, characterized in that an opening portion of the suction passage, which is open to a side wall of the cylinder, is opened and closed at the same time when the piston port is opened and closed.