JPS60198382A - Piston pump - Google Patents

Abstract

PURPOSE:To prevent the generation of cavitation by effecting the same function as that of a check valve with the use of the relative movement between a seal and a piston moving the seal. CONSTITUTION:There is provided a blind hole 12 in the center section of a body 11. A nozzle 13 serving the outlet of hydraulic oil is formed at the front end of the hole 12, and an inlet hole 14 is formed at the rear end of the hole 12 in which there is disposed a slidable piston 15 having a small diameter front end for defining a groove together with the body 11. Further there is provided a hole member 18 having a communication hole 16 perpendicular to the axis and a communication hole 17 communicated between the hole 16 and the front end of the hole member 18. This hole member 18 is disposed in the front end section of the piston 15. Further, a seal 19 disposed in the gap between the hole member 18 and the piston 15 serves the same function as that of a check valve in association with the movement of the piston 15 due to the pressure at the hydraulic oil suction side or the pressure in a pump chamber 27 and the friction of the seal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a relatively short stroke piston pump.

[Conventional temporary phase]

In a conventional reciprocating piston pump, a check valve was installed at the tip of the cylinder to supply low-pressure fluid, but this method requires a large cylinder tip and is expensive.
Also, cavitation occurred due to the resistance of the check valve when the piston retreated.

There is also a method that does not provide a check valve and makes a hole at a position set back the stroke distance from the tip of the cylinder, but with this method, when the piston moves forward, the piston does not have an effective stroke until it closes the hole, and when the piston moves backward, the Since the low-pressure liquid cannot flow in until the liquid passes through the hole, there is a drawback that cavity joists occur.

[Purpose of the invention]

The present invention eliminates these drawbacks, and its purpose is to:
Providing a 7c piston pump that moves the piston forward and moves it forward [(By providing a check valve function with relative movement to the cylinder, the size is reduced and the cost is lowered by 7%) and the occurrence of cavity John is prevented. It's about doing.

[Key points of the invention]

The piston pump of the present invention has a main body, which has a hole at the end, a hydraulic fluid outlet nozzle at the tip of the hole, and a hydraulic fluid inlet hole slightly behind this nozzle, and A piston that slides and has a groove at its tip and a small diameter section at the rear following the groove, a communication hole from the outer periphery of the inner diameter of the piston groove to the tip of the piston, and a hole in the main body that can slide. and a seal inserted into the groove of the piston and arranged with gaps on both sides and the inner surface of the piston.
It is a feature.

Hereinafter, the present invention will be explained in terms of one embodiment. The main body 11 has a hole 12 formed in the center.
Near the tip of 2 is a nozzle 13 for the hydraulic fluid outlet. In addition, near the rear end of the hole 12, there is a structure wJ that connects the outer and inner surfaces.
A liquid inlet hole 14 is provided. The piston 15 is slidably inserted into the hole 12, and its tip is machined to have a small diameter.The piston 15 is a hole member in which a communicating hole 16 in a direction perpendicular to the axis and a communicating hole 17 communicating with the tip are formed at the tip. 18 is screwed on. Since the hole 16 of the hole member 18 has a small diameter, it cooperates with the tip of the piston 15 to form a groove, and a liquid-tight and slidable seal 19 is arranged in the hole 12. ing.

Next, the operation of the embodiment described above will be explained. Since the inlet hole 14 is connected to a liquid source (not shown) which has a sufficient amount of hydraulic fluid with a pressure higher than atmospheric pressure, the working grinder is passed from the inlet hole 14 to the outer circumference of the small diameter portion of the piston 15 in the figure. Cypiston 15
It flows into the cylinder chamber 27 of the hole member 18 through the gap 26 between the front surface of the hole member 1B, the outer circumference of the small diameter part of the hole member 1B, and the side surface and inner circumference of the seal 19, and the communicating holes 16 and 17. Here, when the piston 15 is moved forward (moves to the right), the piston 15
When the front surface 30 of the small diameter portion contacts the surface 31 of the seal 19, the connection between the inlet hole 14 and the gap 26, that is, the cylinder chamber 27 is severed. Therefore, as the piston 15 moves further forward, the hydraulic fluid in the cylinder 27 flows through the hole member 18 and the seal 19.
Pressure increases as the pressure increases and the liquid is either injected from the nozzle 13 or flows into the actuator (not shown).

When the piston 15 advances to the end of its stroke, it retreats to the left. At the beginning of retraction, the cylinder chamber 27 maintains a full high pressure, but this pressure rapidly changes to a low pressure when the seal 19 retracts slightly.

Therefore, the sum of the outer circumferential frictional force of the seal 19 and the force acting on the seal 19 due to the hydraulic fluid pressure on the inlet hole 14 side is the cylinder chamber 27
When the pressure becomes thicker than the force acting on the seal 19,
As shown in the figure again, the surfaces 30 and 31 are separated and the hydraulic fluid flows from the inlet hole 14 to the gap 26 and then to the communication hole 16, as described above.
17 and flows into the cylinder i' 27, so no cavity joists occur. Subsequently, when the piston 15 continues to retreat, the rear surface of the groove of the hole member 18 comes into contact with the front surface of the seal 19, so that the seal 19 is pushed by the hole member 18 and returns to the position shown in the figure.

That is, at the stroke start position 1, the piston 15 continues to move with the seal 19 in a state in which no cavities occur in the piston 27 and sufficient liquid is supplied.

In the above description, the hole member 18 is provided on the front surface of the small diameter portion of the piston 15.
Although the hole member 18 may be integrated with the piston 15, in this case, the seal 19f may be divided into two parts, inserted into the piston 15, and then tightened with a bolt (not shown). .

〔Effect of the invention〕

As explained above, the piston pump of the present invention has a stop hole in the main body, a nozzle that serves as an outlet for the hydraulic fluid at the tip of the hole, and an inlet hole for the hydraulic fluid behind the nozzle. Then, a piston having a tip VC@ and a small diameter portion following this groove is inserted into the hole of the main body, and a seal whose outer periphery is in contact with the hole of the main body is inserted into the groove. Hoko 1/l! The pistons were arranged with a gap between them, and the piston had a hole that communicated from the part that contacted the inside of the seal to the tip.

With this construction, when the piston moves forward, the seal contacts the front surface of the groove of the piston, and the cylinder chamber in front of the piston is disconnected from the inlet hole, resulting in high pressure. - When moving backward, the seal comes into contact with the rear surface of the piston groove, contrary to when moving forward, and the cylinder chamber communicates with the inlet hole, so the hydraulic fluid flows into the cylinder chamber without generating gearvitation. As described above, in the present invention, since the piston and the seal are designed to perform the reverse valve function, there is no need for a separate check valve, and there is an advantage that the shape is small and the cost is low.

[Brief explanation of the drawing]

The figure is a sectional view of one embodiment of the present invention. 11... Main body, 12... Hole, 13... Nozzle, 1
4...Artificial hole, 15...Piston, 16.17...
・4 holes, 19...Seal

Claims (1)

[Claims] A stopper hole is provided at the tip of the main body, which has a nozzle for the outlet of the hydraulic fluid and an inlet hole for the hydraulic fluid at a position slightly behind the nozzle. A piston having a small diameter portion at the rear following the groove and the groove;
The piston has a communication hole extending from the outer periphery of the inner groove to the tip end of the piston, and is slidably inserted into the hole of the main body, and is arranged with gaps on both sides and a circular surface with respect to the groove of the piston. A piston pump consisting of a cylinder and a cylinder.