JP2942902B2 - Air-driven pump - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-driven pump used as a hydraulic pressure generator in a portable hydraulic jack or the like.

[Conventional technology]

An air-driven pump, which generates a high-pressure oil source or the like by driving a piston by air pressure, is useful as a device that exerts a booster function in a pressure system by operating a piston having a different pressure receiving area. Supply / discharge control is required.

FIG. 3 is a longitudinal sectional view showing such a conventional air-driven pump, and FIG. 2 is a side view showing the arrangement of the valve housing. Reference numeral 1 denotes a cylinder tube, on which a piston 2 having a piston ring 3 is slidably provided. Further, the piston 2 separates the first cylinder chamber C and the second cylinder chamber D. A pilot air pressure control plunger 4 is mounted on one side of the piston 2 in a sealed state by an O-ring 5, and a hydraulic pressure generating plunger 7 is mounted on the other side of the piston 2 via a spacer 6. The plungers 4 and 7 move integrally with the piston 2. A return spring 10 is disposed between the piston 2 and the cylinder cap 11 on the side where the hydraulic pressure generating plunger 7 is mounted via a plate 9 having a cushion rubber 8.

Reference numeral 12 denotes a nut portion of the pump housing, which is fixed to the cylinder cap 11 by a lock nut 13, and a plunger 7 for generating hydraulic pressure is inserted into a central chamber portion thereof in a sliding state by an O-ring 14, a backup ring 15, and a bush 16. It is. Reference numeral 17 denotes a cap nut for holding a seal portion such as the bush 16 and 18 denotes a pin for fixing the return spring 10.

On the other hand, the control plunger 4 is inserted through a central hole of a valve housing 19 which is fixed to the other end of the cylinder tube 1 by an O-ring 20 in a sealed state. The housing 19 is provided with a poppet 21 in parallel with the position where the pilot air pressure control plunger 4 is inserted, and the tip of a valve shaft 23 supporting the valve seat 22 is attached to the housing 19.
It faces a first cylinder chamber C formed between the inner wall and the piston 2. Therefore, when the valve seat 22 moves to the valve opening position away from the valve seat 24, the valve shaft 23 is caused to enter the stroke area of the piston 2. Further, in the housing 19, an air supply port P communicating with the first cylinder chamber C and an exhaust port T '(see FIG. 2) communicating with the first cylinder chamber C via the poppet 21 are provided. is there.

A space in the valve housing 19 facing the tip of the pilot air pressure control plunger 4 is defined as a pilot chamber a which is communicated with the poppet chamber a 'of the poppet 21 through the passage d. A pilot port e communicating with the pilot chamber a is provided with a pilot air pressure control plunger 4.
An exhaust port b is opened in the center hole wall for sliding the plunger through which the pilot port e moves, and a passage is formed through the poppet 21 to the exhaust port T '.

 Next, the operation will be described.

Now, when air pressure is sent from the intake port P into the first cylinder chamber C, the piston 2 moves to the left. The plungers 4 and 7 move in conjunction with this, and the plunger 7 for generating hydraulic pressure to the hydraulic chamber in the pump housing 12A.
, The hydraulic oil in the chamber is compressed.

At the same time, when the other pilot air pressure control plunger 4 moves, the pilot port e comes out of the sliding hole of the valve housing 19 and reaches the first cylinder chamber C, and the air pressure in the first cylinder chamber C is reduced to the port. e is introduced into the poppet chamber a 'through the pilot chamber a and the passage d. Then, the poppet 21 a is pressurized by the poppet chamber a ′.
The valve shaft 23 is pushed leftward to move, and the valve seat 22 that has been in the open state in close contact with the valve seat 24 is separated from the valve seat 24 to open. As a result, the first cylinder chamber C communicates with the exhaust port T 'through the gap of the valve shaft 23,
Is released into the atmosphere.

When the air pressure in the first cylinder chamber C is released, the piston 2 is pushed rightward by the expansion pressure of the return spring 10 to move and return. In this process, the pilot 2 provided on the pilot air pressure control plunger 4 is provided. When the port e passes through the exhaust port b, the air pressure in the poppet chamber a 'is released through the passage d, the pilot chamber a, the pilot port e, the exhaust port and the gap between the poppet valve shaft 23 and the exhaust port T'.
Discharged from

In the death point region of the piston return operation by the return spring 10, the piston 2 comes into contact with the tip of the valve shaft 23 which has protruded into the stroke region when the valve is opened, and pushes it to the right. For this reason, the valve seat 22 integrated with the valve shaft 23 is
The poppet 21 pressed against 24 is reclosed. Thereafter, by repeating such an operation, the pressurizing operation of the hydraulic chamber with the check valve by the hydraulic pressure generating plunger 7 is continuously performed.

By the way, at the beginning of the return stroke of the piston 2, the air in the first cylinder chamber C is discharged from the small-diameter exhaust port T 'by the opening of the valve seat 22 from the valve seat 24 due to the sliding of the poppet 21. However, at the time of discharge, the exhaust port T '
Loud exhaust noise. For this reason, a sound-absorbing element for suppressing noise has been mounted on the exhaust port T 'so that the noise is suppressed to a level that does not cause annoyance.

[Problems to be solved by the invention]

Since the conventional air-driven pump is configured as described above, if the silencing element is attached to the exhaust port T 'to prevent exhaust noise as described above, the airflow resistance will increase, and the first cylinder chamber will increase. There is a problem that a back pressure is generated in C, the return operation of the piston 2 is delayed, and the number of operations is reduced.

The present invention has been made in view of the conventional problems as described above, and has a high efficiency in which exhaust noise can be suppressed to a sufficiently low level and the operating speed of a piston can be maintained at a sufficiently high level. It is an object of the present invention to provide a type of air-driven pump.

[Means for solving the problem]

In order to achieve the above object, a means of the present invention comprises a piston movably inserted into a cylinder tube, a first cylinder chamber and a second cylinder chamber separated by a piston in the cylinder tube, A plunger for generating hydraulic pressure and a plunger for controlling pilot air pressure connected to both sides of the cylinder, a spring for returning a piston disposed in the second cylinder chamber, an air supply port connected to the first cylinder chamber, and a cylinder. An exhaust port provided in the tube and connected to the atmosphere side, a poppet selectively communicating or blocking the first cylinder chamber with the exhaust port, a poppet chamber provided on the back of the poppet, and a pilot air pressure control plunger -Driven pump provided with a pilot port for selectively opening and closing the poppet chamber to the first cylinder chamber or the exhaust port In the above, an air passage connecting the exhaust port to the second cylinder chamber, an exhaust passage connecting the second cylinder chamber to the atmosphere, and a silencing element provided in the middle of the exhaust passage are provided. It is a feature.

[Action]

Since the air passage in the present invention connects the first cylinder chamber and the second cylinder chamber through the exhaust port, the exhaust pressure from the first cylinder chamber is balanced on both sides of the piston. The exhaust pressure is kept at the second level even if a noise reduction element is attached to the end of the exhaust passage communicating with the second cylinder chamber so as not to be affected.
Therefore, the exhaust noise can be suppressed to a sufficiently low level.

(Example of the invention)

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2. The air-driven pump according to this embodiment includes a piston 2 movably inserted into a cylinder tube 1, a first cylinder chamber C and a second cylinder chamber D separated by the piston 2 in the cylinder tube 1. A hydraulic pressure generating plunger 7 and a pilot air pressure controlling plunger 4 connected to both sides of the piston 2, a piston return spring 10 disposed in the second cylinder chamber D,
An air supply port P connected to the first cylinder chamber C, an exhaust port provided in the cylinder tube 1 and connected to the atmosphere,
A poppet 21 for selectively communicating or shutting off the first cylinder chamber C with the exhaust port, a poppet chamber provided on the back of the poppet 21, and a poppet chamber provided on the plunger 4 for pilot air pressure control, and A pilot port e for selectively opening and closing the chamber C or the exhaust port is provided. Further, this air-driven pump is not provided in an air passage 32 connecting the exhaust port and the second cylinder chamber D, an exhaust passage 33 connecting the second cylinder chamber D and the atmosphere, and in the middle of the exhaust passage 33. A muffling element 34 is provided. This will be described in detail above. In FIG. 1, T ₁ is a vent port communicating with a pilot port b, an outer peripheral gap of the valve shaft 23 and an exhaust port T ′, and R is an intake port formed in the cylinder tube 1, which is separated by a piston 2. And penetrates into and out of the second cylinder chamber D. 31 is the cylinder tube 1
In hermetically mounted ventilation covers the outer peripheral surface side of, in the ventilation cover 31 is an air passage 32 communicating with the vent T ₁ and inlet R. 33 is pump housing 12
An exhaust passage formed in A, one end of which opens into the second cylinder chamber D, and the other end opens outward from the outer periphery of the pump housing 12A as shown in FIG. And
At the exhaust end 33a, which is an opening to the outside, a silencing element 34 for silencing exhaust noise is provided with a snap ring 35.
It is attached interchangeably by. In addition, it is optional to use a push nut instead of the snap ring 35 as necessary. In addition, the same components as those shown in FIG. 3 are denoted by the same reference numerals, and redundant description will be omitted.

 Next, the operation will be described.

First, when air pressure is sent from the intake port P to the first cylinder chamber C, the piston 2 moves to the left. The plungers 4 and 7 move in conjunction with this, and the plunger 7 for generating hydraulic pressure to the hydraulic chamber in the pump housing 12A.
, The hydraulic oil in the chamber is compressed. At the same time, when the other pilot air pressure control plunger 4 moves, the pilot port e comes out of the sliding hole of the valve housing 19 and reaches the first cylinder chamber C, and the air pressure in the first cylinder chamber C is reduced to the port. e is introduced into the poppet chamber a 'through the pilot chamber a and the passage d. Then, the valve shaft 23 of the poppet 21 is pushed to the left by the pressurization of the poppet chamber a 'and moves, and the valve seat 22 which has been in close contact with the valve seat 24 and is in the closed state is moved from the valve seat 24. The valve is opened. As a result, the first cylinder chamber C is
The air pressure in the first cylinder chamber C is released to the atmosphere via an exhaust passage described later, communicating with the exhaust port T 'through a gap 23.

When the air pressure in the first cylinder chamber C is released, the piston 2 is pushed rightward by the expansion pressure of the return spring 10 to move and return. In this process, the pilot 2 provided on the pilot air pressure control plunger 4 is provided. When the port e passes through the exhaust port b, the air pressure in the poppet chamber a 'is released through the passage d, the pilot chamber a, the pilot port e, the exhaust port and the gap between the poppet valve shaft 23 and the exhaust port T'.
Discharged from

On the other hand, the first cylinder chamber C is provided with the valve shaft 23 of the poppet 21.
Through the outer peripheral portion outlet T as described above 'when communicating with the air pressure in the first cylinder chamber C is, the exhaust port T' vent T ₁ which communicates with and thereto, the vent cover 31 The air is once introduced into the second cylinder chamber D through the separated air passage 32 and the intake port R. The air pressure introduced into the second cylinder chamber D is further discharged out of the cylinder tube 1 through an exhaust passage 33 and a silencing element 34 provided in the pump housing 12A. As described above, when the air pressure in the first cylinder chamber C is exhausted, the air is once sent into the second cylinder chamber D via the air passage 32, so that the air pressures on both sides of the piston 2 are balanced, and the exhaust end Even if the muffling element 34 is provided in the portion 33a, the piston 2 can be returned lightly and quickly by only the repulsive force of the return spring 10 without being affected by the back pressure. As a result, there is an advantage that the number of pump operations increases and the hydraulic discharge amount increases. Further, since the air pressure from the exhaust port T 'enters the second cylinder chamber D having a large volume, the exhaust pressure is temporarily reduced, and the exhaust passage 33 is maintained in a state where the exhaust pressure is reduced. Exhaust gas to the outside of the cylinder tube 1, exhaust noise is inevitably reduced. Therefore, by using the silencing element 34 in combination, the generation of exhaust noise can be suppressed to an extremely low level.

〔The invention's effect〕

 According to the present invention, the following effects are obtained.

(1) Since the exhaust port is connected to the second cylinder chamber via the air passage, the exhaust pressure exhausted from the first cylinder chamber temporarily increases through the exhaust port and the air passage. The exhaust pressure is reduced because it is discharged to the exhaust passage, and the exhaust pressure in the exhaust passage is also reduced, so that exhaust noise can be suppressed to a low level. In addition, a silencing element is provided in the middle of the exhaust port, so the noise is reduced Is further improved.

(2) Similarly, since the first cylinder chamber and the second cylinder chamber are in communication with the exhaust port via the air passage during the exhaust operation, the internal pressures of both chambers are balanced, and are affected by the internal pressure of the first cylinder chamber. The piston can be returned to the original neutral position only by the return force of the return spring without any return, the return operation is quick and light, and the pump operation cycle can be accelerated to increase the hydraulic discharge amount.

[Brief description of the drawings]

1 is a longitudinal sectional view showing an air-driven pump according to an embodiment of the present invention, FIG. 2 is a cut-away view of a main part of a pump housing in FIG. 1, and a longitudinal sectional view showing a conventional air-driven pump shown in FIG. FIG. 4 is a side view of the air-driven pump shown in FIG. 1 ... Cylinder tube, 2 ... Piston, 4 ... Plunger for pilot air pressure control, 7 ... Plunger for hydraulic pressure generation, 10 ... Return spring, 21 ... Poppet, 22
... valve seat, 32 ... air passage, 34 ... silencing element, C ... first cylinder chamber, D ... second cylinder chamber, P ... air supply port, b ... pilot passage, T ' ……exhaust port.

Claims (1)

(57) [Claims] 1. A piston movably inserted into a cylinder tube, a first cylinder chamber and a second cylinder chamber separated by a piston in the cylinder tube, and a hydraulic pressure generator provided on both sides of the piston. Plunger and pilot air pressure control plunger, a piston return spring disposed in the second cylinder chamber, an air supply port connected to the first cylinder chamber, and a cylinder tube connected to the atmosphere. A poppet chamber for selectively communicating or blocking the first cylinder chamber with the exhaust port, a poppet chamber provided on the back of the poppet, and a poppet chamber provided on the plunger for pilot air pressure control. An air-driven pump provided with a pilot port for selectively opening and closing a cylinder chamber or an exhaust port of the exhaust port and the second cylinder. Air-driven pump, wherein an air passage connecting the door, and an exhaust passage which connects the second cylinder chamber and the atmosphere, in that a and silencer elements provided in an intermediate portion of an exhaust passage.