KR101658358B1

KR101658358B1 - Air pressure motors

Info

Publication number: KR101658358B1
Application number: KR1020150160107A
Authority: KR
Inventors: 박근조; 김재룡; 박광수
Original assignee: (주)대신테크
Priority date: 2015-11-16
Filing date: 2015-11-16
Publication date: 2016-09-30

Abstract

The present invention relates to a pneumatic motor. More particularly, the present invention relates to a pneumatic motor. More particularly, the present invention relates to a pneumatic motor. More particularly, the present invention relates to a pneumatic motor, To a pneumatic motor.
The present invention relates to a cylinder (10) comprising a cylinder (10), a base (20) fastened to the lower portion of the cylinder (10) to form a closed space, A piston valve 45 for supplying compressed air alternately to the upper portion of the piston and the lower portion of the piston, a valve housing 40 for guiding the piston valve 45, A pneumatic motor having an upper valve 60 and a lower valve 61 for reciprocating in the cylinder and a piston rod 51 penetrating the base and fastened to the piston 50, , Said cylinder (10) having a lip (17) in radial form on its outer surface, said base (20) comprising: a cavity (27) And an external lower valve (61) fastened to an upper end of the concave cavity (27).

Description

Air pressure motors

The present invention relates to a pneumatic motor. More particularly, the present invention relates to a pneumatic motor. More particularly, the present invention relates to a pneumatic motor. More particularly, the present invention relates to a pneumatic motor, To a pneumatic motor.

The pneumatic motor of the present invention is a reciprocating piston type and is used as a power source for driving a high-pressure pump connected to the lower portion while reciprocating the piston up and down with supplied compressed air.

The piston of the pneumatic motor is driven in an upward stroke or a downward stroke while the valve is opened while the intake pipe is switched up and down while being in contact with the poppet valve in the upper valve and the lower valve.

The pneumatic motor sucks compressed air into the cylinder and drives the piston. As the compressed air is instantaneously discharged, moisture in the air is converted into ice around the exhaust pipe. The ice is adhered to the exhaust pipe by continuous driving of the pneumatic motor, and other ice is further adhered to the exhaust pipe to block the exhaust pipe, thereby stopping the operation of the pneumatic motor. Due to the above reasons, the continuous driving time of the pneumatic motor generally does not exceed 2 to 3 hours.

The valve of the pneumatic motor is in contact with the piston, and sometimes the poppet valve is damaged by the piston, and the exhaust pipe and valve may be damaged by the cooling.

Since the upper valve of the pneumatic motor is external and located at the upper part of the opened cylinder, it is easily replaceable. However, since the lower valve of the pneumatic motor is located at the upper end of the base, it is troublesome to disassemble the cylinder and the pneumatic motor in order to replace the lower valve have.

Therefore, there is a need for a technique capable of replacing and replacing the lower valve easily without disassembling the cylinder and the pneumatic motor.

Further, the base of the pneumatic motor guides the piston rod passing through the center portion. However, the long-time driven pneumatic motor has a problem that the base or the pneumatic motor must be replaced due to the friction between the piston rod and the base.

Therefore, it is necessary to improve the durability of the piston rod and the base, and to recycle the base only by exchanging the parts.

1. KR 10-1310083, 'Reciprocating air motor', registration date: 2013.09.12. 2. KR 10-0878643, 'Rubber sleeve circular holding device', registration date: 2009.01.07. 3. KR 10-2013-0133758 A, 'Sleeve / liner assembly and hydraulic hammer using it', Published on: December 31, 2013.

The present invention has been made to solve the above problems,

In order to compensate for the rigidity of the pneumatic motor due to the weight reduction of the cylinder, a lip is added to the outer shape of the cylinder, and a cavity is formed in the base for replacing the lower valve without disassembling the pneumatic motor, and a lower valve It is an object of the present invention to disclose a pneumatic motor.

It is another object of the present invention to disclose a pneumatic motor having a liner provided with an oil reservoir for reducing frictional resistance between a piston rod for reciprocating up and down movement and a base for guiding the piston rod and for easily recycling a damaged liner It is another object of the invention.

The present invention provides a cylinder assembly including a cylinder and a base which is tightened at a lower portion of the cylinder to form a closed space, A piston valve 45 for supplying compressed air supplied to the cylinder to the upper portion of the piston and the lower portion of the piston alternately, a valve housing 40 for guiding the piston valve 45, An upper valve 60 and a lower valve 61 for switching the position of the piston 45 and a piston 50 reciprocating in the cylinder and a piston rod 51 , Characterized in that the cylinder (10) has a lip (17) in the form of a radiation in its outer shape, and the base (20) comprises a cavity (27) recessed on one side of the outer shape; And an external lower valve (61) fastened to the upper end of the concave cavity (27).

The upper valve 60 and the lower valve 61 of the present invention further include a poppet valve 65 that vertically moves in contact with the piston 50; A spring 64 coupled between the poppet valve 65 and the valve cap 62 and returning the poppet valve 65 to its original position; A housing 63b connected to the intake pipe I and the exhaust pipe E while accommodating the spring; A valve cap 62a for fixing the spring 64 and the housing 63a; Wherein the housing (63a) has two channels connecting the intake pipe (I) and the exhaust pipe (E).

The conduit connecting the valve housing 40 of the present invention to the upper valve 61 to the lower valve 61 is composed only of the intake pipe I and the discharge pipe E and is connected to the discharge pipe E And a hole is provided in any one of the one side of the cylinder (10) or one side of the valve housing (40) to discharge the compressed air remaining in the discharge pipe and the closed space to the outside.

In order to reduce the friction between the piston rod and the base of the pneumatic motor, the base 20 of the pneumatic motor also includes a circular liner 28 for guiding the piston rod 51; And at least one oil reservoir (29) at one side of the inner side of the liner (28).

Further, in order to recycle the liner used for a long time, the oil reservoir 29 of the liner is provided with a structure capable of accommodating the sleeve length and thickness to be additionally inserted.

The present invention has the following effects due to the above-mentioned solution.

First, the weight can be reduced by about 30% compared with the conventional one by weight reduction of the cylinder, and the durability has the same effect due to the cylinder added with the lip.

Secondly, when the lower valve 25 is replaced with the cavity 27 formed in the base and the lower valve 25 fastened to the cavity 27, the pneumatic motor can be replaced without disassembly, It can be greatly shortened.

Third, a pneumatic motor having a lighter equipped with an oil reservoir reduces the frictional resistance between the base and the piston rod, and can be reused by adding a sleeve easily after a long period of use, .

1 is a connection state diagram of a pneumatic motor and a high-pressure pump according to the present invention.
2 is a perspective view of a preferred embodiment of the present invention;
3 is a configuration diagram of a pneumatic motor.
4 is a perspective view of the base 20 and the lower valve 25 of the pneumatic motor.
5 is a sectional view of the pneumatic motor of the present invention (A) and the prior art (B).
6 is a sectional view of the upper valve 60 of the present invention (A) and the prior art (B).
Fig. 7 is an operational state diagram of the closing (A) and opening (B) of the upper and lower valves 60 and 61. Fig.
Fig. 8 is a view for comparing the intake pipe and the exhaust pipe of the present invention (A) and the prior art (B). Fig.
9 is a perspective view and a bottom view of the base 20 of the present invention (A) and the prior art (B).
10 is a cross-sectional view of the base 20. Fig.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is a perspective view of a preferred embodiment of the present invention, and Fig. 3 is a configuration diagram of a pneumatic motor. Fig.

The present invention relates to a cylinder (10) comprising a cylinder (10), a base (20) fastened to the lower portion of the cylinder (10) to form a closed space, A piston valve 45 for supplying compressed air alternately to the upper portion of the piston and the lower portion of the piston, a valve housing 40 for guiding the piston valve 45, A pneumatic motor having an upper valve 60 and a lower valve 61 for reciprocating in the cylinder and a piston rod 51 penetrating the base and fastened to the piston 50, , Said cylinder (10) having a lip (17) in radial form on its outer surface, said base (20) comprising: a cavity (27) And an external lower valve (61) fastened to an upper end of the concave cavity (27).

1 shows a pneumatic motor connected to the high-pressure pump 30. However, the pneumatic motor of the present invention can be variously applied by being fastened to various types of accessory devices.

The high-pressure pump 30 is coupled to the piston rod through a connector. The high-pressure pump 30 sucks the transporting paint and the liquid material into the suction port 32, and discharges the high-pressure fluid to the discharge port 33 at a high pressure.

The pneumatic motor is connected to a pipe for supplying compressed air and a suction port (41) of the valve housing (40). The valve housing 40 has a closed cylinder structure and guides the reciprocating motion of the piston valve 45. With the upward and downward switching of the piston valve 45, the compressed air is supplied to the cylinder 10 via the main air line 46. The supplied compressed air moves the piston up and down and drives the high pressure pump 30 connected to the piston rod 51.

With the contraction of the internal space due to the movement of the piston 50, the air on the opposite side of the piston 50 is discharged to the discharge port 16 through the main air path 46.

The base 20 has a plurality of coupling grooves 23 at an upper end thereof and is fastened to the lower end of the cylinder 10 by a base fastening bolt 15.

In addition, the base 20 forms a closed space together with the cylinder 10 fastened to the upper end, and the center portion may have a structure in which the piston rod 51 can penetrate.

It is preferable that the upper end portion includes an insertion groove 24 through which the poppet valve 65 penetrates and the insertion groove 24 has a receiving portion capable of receiving the lower valve 61.

The insertion groove 24 is connected to the valve housing 40 attached to the cylinder side surface through the intake pipe I and the discharge pipe E.

The upper valve 60 and the lower valve 61 are valves for switching the piston valve 45 in the valve housing 40. That is, the compressed air is supplied to the closed space 47 formed in the valve housing 40 so that the piston valve 45 is switched up and down.

The upper valve 60 and the lower valve 61 have a poppet valve 65 and are opened and closed while being in contact with the piston. The poppet valve 65 is opened and closed before the piston 50 reaches the top dead center or the bottom dead center, The poppet valve 65 is opened.

When the poppet valve 65 is opened, the compressed air flowing into the intake pipe I is supplied to the closed space 47 formed in the valve housing 40 via the poppet valve 65.

The compressed air supplied to the closed space 47 moves the piston valve 45 in the opposite direction.

When the piston valve 45 moves, the main air passage 46 is changed to change the moving direction of the piston 50.

After that, the residual air in the closed space formed in the valve housing 40 is discharged to the outside through the residual air discharge pipe and returned to the atmospheric pressure state.

For details of the driving mechanism of the upper valve, refer to KR 10-1310083 (registration date: 2013.09.12, 'Reciprocating air motor') which is registered and registered by the present applicant.

The present invention intends to disclose an improved technique in the prior art to KR 10-1310083 (registration date: 2013.09.12, " reciprocating air motor ") filed and filed by the present applicant.

The present invention has three main objectives.

First, in order to reduce the weight of the cylinder 50%, the cylinder thickness should be made 70% or more thinner than the conventional one.

Second, the shape and structure of the base are changed so that the lower valve 61 can be replaced without disassembling the cylinder and the base.

Third, a method of extending the life of the base that guides the piston rod in the base and reducing the frictional resistance is disclosed.

Fourth, a method of simply assembling or disassembling the pneumatic motor by simplifying parts of the upper valve and the lower valve is disclosed.

In order to satisfy the first object of the present invention, the present invention firstly manufactures a cylinder having a thickness of 70% or more smaller than the conventional one. However, it is preferable that the lip 17 having a constant width in the outer portion of the cylinder and having a thickness of about 1 mm or more larger than the outer diameter of the cylinder is formed radially with respect to the center.

The pneumatic motor is supplied with compressed air of 3 to 7 bar and generates a high force corresponding to the inner diameter of the cylinder and the outer diameter area ratio of the piston rod. The high pressure pump 30 is driven by the high force of the pneumatic motor to transfer the paint and the liquid material.

Therefore, the pressure applied to the cylinder 10 is within 10 bar at maximum, and a thickness of 2 mm or less is sufficient even if the function and safety factor of the pneumatic motor are taken into account. However, as gravity casting is used, the thickness may increase somewhat considering the gradient angle and the formation of the casting material.

In addition, the radial lip 17 has a function as a stiffener that fits a circular cylinder, is stable compared to an eccentrically formed lip, and reinforces the outer wall of the thinned cylinder.

4 is a perspective view of the base 20 and the lower valve 25 of the pneumatic motor. Fig. 5 is a sectional view of the pneumatic motor of the present invention (A) and the prior art (B) A perspective view and a bottom view of the base 20 of the technique (B).

In order to attain the second object of the present invention, the base (20) is characterized by having a cavity (27) concaved on one side thereof.

Referring to FIG. 9B, the pneumatic motor base 20 of the prior art has an outer shape formed in a cylindrical shape, and has an accommodating portion of a lower valve 61 at an upper end thereof.

6B, the conventional upper valve 60 includes a poppet valve 65 reciprocating vertically while being in contact with the piston 50, a spring 64 for returning the poppet valve 65 to its original position, A housing 63b connected to the intake pipe I and the exhaust pipe E while accommodating the spring and a valve cap 62b for fixing the spring 64 and the housing 63b.

If the conventional upper valve 60 is of the external type, the lower valve 61 is embedded in the space formed in the upper end of the base, so that the valve cap 62b does not exist in the constituent elements of the upper valve 60. This is because the base 20 replaces the function of the valve cap 62b.

3 to 5B, in order to replace the lower valve 61 in the prior art pneumatic motor, the housing fastening bolt 13 is first removed and the valve housing 40 is removed. Next, after removing the base fastening bolt 15 to separate the cylinder 10 and the base 20, the lower valve 61 fastened to the upper portion of the base 20 must be replaced and assembled in the reverse order .

That is, in order to replace the built-in lower valve 61, the entire pneumatic motor has to be disassembled.

9A, a cavity 27 is formed at one side of the outer contour of the base 20, and an external bottom valve 61 is provided at the upper end of the concave cavity 27 So that it can be fastened.

The poppet valve (65) of the lower valve (61) projects through the insertion groove (24) of the base (20). The poppet valve 65 vertically moves the poppet valve 65 while contacting the piston so that the intake pipe I and the exhaust pipe E communicate with each other when the piston 50 reaches the top dead center or the bottom dead center Open.

In the present invention, the concave cavity 27 of the base 20 is formed by cutting one side of the cylindrical base 20 of the prior art and replacing it with a base having an accommodating portion capable of accommodating the external lower valve 61 . The above description is preferably included in the scope of the present invention.

4 is a perspective view of the base 20 and the lower valve 61 of the pneumatic motor.

4, the recessed cavity 27 in the outer side of the base 20 and the configuration of the external type lower valve 61 are the same as those of the prior art in which the pneumatic motor has to be disassembled completely in order to replace the lower valve 61 Since only the lower valve 61 assembled in an external shape can be exchanged, it is possible to drastically shorten the working time due to the exchange.

6 is a cross-sectional view of the upper valve 60 of the present invention (A) and the prior art (B), and Fig. 7 is a sectional view of the upper and lower valves 60 And FIG. 8 is a view for comparing the intake pipe and the exhaust pipe of the present invention (A) and the conventional technique (B).

Compressed air is supplied to the cylinder (10) and compressed air is sequentially supplied to the upper portion of the piston and the lower portion of the piston to reciprocate the piston (50).

The piston valve 45 is a switching valve for supplying compressed air alternately to the upper and lower portions of the piston. The piston valve 45 has a function of alternately connecting the main air passage 45 and the exhaust pipe 15.

The compressed air supplied to the intake pipe 41 of the valve housing 40 flows into the cylinder through the main air pipe line 46 connected to the upper portion and the lower portion of the piston by the piston valve 45.

The upper valve 60 and the lower valve 61 correspond to a switch valve for switching the piston valve 45. When the piston 50 reaches the vicinity of the top dead center or the bottom dead center, Thereby supplying compressed air for changing the position of the piston valve 45.

The shape of the piston valve 45 and the intake pipe I connected to the upper valve 60 and the lower valve 61 and the exhaust pipe E are connected to each other.

Compressed air is supplied to the main air passage (45) and the intake pipe (I) at the upper portion or the lower portion of the piston to which the compressed air is supplied. However, the main air pipe is open, and the intake pipe I is kept closed by the poppet valve.

When the piston reaches the top dead center or the bottom dead center and the poppet valve 65 is opened while vertically climbing while contacting the poppet valve 65, the compressed air closed by the poppet valve as shown in Fig. And the exhaust pipe E is connected to the valve housing 40 so that the compressed air flows into the muffle space 47 of the valve housing to move the piston valve 45 to the opposite side .

The intake pipe I is connected to the valve housing 40 and the upper and lower valves 60 and 61 while the intake pipe I is connected to the valve housing 40 and the upper and lower valves 60 and 61, And the exhaust pipe E is connected to a closed space 47 formed at an upper end portion and a lower end portion of the piston valve and the residual gas discharge pipe S is formed at one side portion of the valve housing 40, .

The piston valve 45 moves to the opposite side and switches the connection between the main air passage and the discharge port connected to the cylinder to an upper portion or a lower portion of the piston.

When the supply line of the compressed air is switched to the upper portion or the lower portion of the piston, the piston moves in the opposite direction. As the piston 50 moves, the poppet valve 65 returns to its original state, do.

The compressed air remaining in the closed space 47 and the exhaust pipe E must be decompressed to an atmospheric pressure state for the next stroke.

As in FIG. 5B or FIG. 8B, the prior art has a separate residual air discharge pipe (S) and a discharge port for discharging the residual compressed air.

6B, in the state where the poppet valve 65 is closed in the related art, the exhaust pipe E and the residual air discharge pipe S are opened to discharge the residual compressed air through the outlet opening to the outside.

However, in the present invention, the valve housing (40) has a very small diameter groove on one side. That is, grooves are formed in the closed space 47, and small holes are formed so that compressed air is not temporarily discharged.

It is possible to switch the piston valve 45 by providing the small hole so that the compressed air flowing into the discharge pipe E does not cause any difficulty in switching the position of the piston valve 45, And discharging the remaining compressed air to the outside.

The hole may be formed on one side of the valve housing or on one side of the cylinder connected to the discharge pipe E and the most ideal position is a hole formed in the fastening portion of the cylinder 10 and the valve housing 40 .

This small hole has the effect of excluding the residual air discharge pipe (S) and the discharge port which are used in the prior art.

Therefore, in the present invention, the pipe connecting the valve housing 40 and the upper valve 61 to the lower valve 61 is composed only of the intake pipe I and the discharge pipe E, and is connected to the discharge pipe E A hole is provided at one side of the cylinder 10 or in the valve housing 40 so as to discharge the compressed air remaining in the discharge pipe and the closed space to the outside.

5 to 8, three connecting pipes are required for the upper valve 60 and the lower valve 61 in the prior art and the housing 63B of the upper valve 60 and the lower valve 61, The structure of the cap is complicated.

However, the present invention is characterized by an upper valve 60 and a lower valve 61 having two connecting pipes I and E and a housing 63a connected to the two connecting pipes.

The upper and lower valves 60 and 61 of the present invention include a poppet valve 65 that vertically moves in contact with the piston 50, as shown in FIG. 6A; A spring 64 coupled between the poppet valve 65 and the valve cap 62 and returning the poppet valve 65 to its original position; A housing 63b connected to the intake pipe I and the exhaust pipe E while receiving the spring; a valve cap 62a for fixing the spring 64 and the housing 63a; Wherein the housing (63a) has two channels connecting the intake pipe (I) and the exhaust pipe (E).

As shown in Fig. 6B, the prior art upper and lower valves 60 and 61 have a structure in which the valve gap 62b and the housing 63b are separated from each other, and are located in the narrow and deep accommodating portion, In this case, there is a disadvantage in that the work process and time are very useful.

Accordingly, in order to solve the above problem, the valve cap 62a is changed into a structure to be coupled with the inside of the housing 63a, and a part of the conventional housing 63b and the valve cap 62b are integrated.

In this configuration, the upper and lower valves 60 and 61 are formed in an external shape, and the valve cap and the housing are integrally formed to provide convenience in assembling and exchanging operations.

In the prior art, the intake pipe I is connected to the valve cap 62a and the exhaust pipe E and the residual gas discharge pipe S are connected to each other in the housing. In the present invention, the intake pipe I is connected to the housing 63a, And the exhaust pipe (E) are connected, and there is no residual gas discharge pipe (S).

With the above-described structure, the components of the upper valve 60 and the lower valve 61 are simplified, thereby lowering the height of the upper and lower valves 60 and 61, and a compact pneumatic motor can be realized.

10 is a sectional view of the base 20. Fig.

In order to achieve the third object of the present invention, the base (20) comprises a circular liner (28) for guiding the piston rod (51); And one or more oil reservoirs 29 on one side of the inner side of the liner 28.

In a pneumatic motor driven for a long time in general, the piston rod 51 and the center portion of the base 20 for guiding the piston rod are worn and the piston 50 reciprocates vertically while being shaken. Therefore, the life of the high-pressure pump 30 fastened to the piston rod 51 is also shortened, and the pneumatic motor and the entire base have to be replaced.

The base 20 mainly has four functions. First, the piston is fastened to the bottom of the cylinder to form a closed space to multiply the compression force on the piston. Second, the moving direction of the piston rod passing through the center portion is guided. Third, it has a role of supporting the high pressure pump fastened to the rod. Fourth, it serves as an air connection passage having a lower valve, an air intake pipe, and an air exhaust pipe at one side of the base.

Referring to FIG. 10, the third object of the present invention is to enhance the function of the center portion for guiding the piston rod 51 among the functions of the base 20.

A liner 28 is typically used in a reciprocating piston type where there is a high degree of frictional wear. When wear is severe in the liner 28 in the painting pneumatic motor, it is often the case that a sleeve is inserted into the upper end portion and the lower end portion of the liner, and then a sleeve is added to the inserting portion for reuse.

By applying the method of the present invention, the base 20 of the present invention comprises a circular liner 28 for guiding the piston rod 51; And one or more oil reservoirs 29 at one side of the inner side of the liner 28. The oil reservoir 29 is formed to have a structure capable of accommodating the sleeve length and thickness to be additionally inserted .

The oil reservoir 29 is preferably located at the upper end and the lower end of the liner 28, and is preferably formed at a constant spacing at both ends.

The sleeve means a cylindrical cylinder, and it is preferable to use the same material as the liner 28.

Due to the present invention, the oil reservoir 29 into which the sleeve can be inserted is normally filled with lubricating oil such as grease to reduce the frictional resistance between the piston rod 51 and the liner 28, When the sleeve is added to the upper end portion and the lower end portion, the sleeve can be added and used without additional processing.

In addition, since the liner 28 having the oil reservoir 29 can be reused by adding only a sleeve at a work site, it can be immediately repaired at a work site.

10: cylinder, 12: valve housing gasket, 13: housing fastening bolt,
14: cylinder gasket, 15: base fastening bolt, 16:
17: rib, 20: base, 21: o-ring,
23: fastening groove, 24: insertion groove,
27: concave cavity part, 28: liner, 29: oil storage part,
30: high pressure pump, 31: rod, 32: suction port,
33: discharge port, 40: valve housing, 41: compressed air inlet,
45: Piston valve, 46: Main air passage, 47: Sealed space
50: piston, 51: piston rod,
60: upper valve, 61: lower valve, 62: valve cap,
63: housing 64: spring, 65: poppet valve,
I: intake pipe, E: exhaust pipe, S: residual air

Claims

A cylinder 10 and a base 20 which are connected to a lower portion of the cylinder 10 to form an airtight space and a piston 20 connected to one side of the cylinder 10 and the base 20, A piston valve 45 for alternately supplying compressed air to the lower portion of the piston and a lower portion of the piston, a valve housing 40 for guiding the piston valve 45 and an upper valve (not shown) for switching the position of the piston valve 45 A pneumatic motor having a piston (60) and a lower valve (61), a piston (50) reciprocating in the cylinder, and a piston rod (51) penetrating the base and fastened to the piston (50)
The cylinder (10)
(17) in the form of a radiation in the outer part,
The base (20)
A cavity (27) recessed on one side of the outer contour;
And an external bottom valve (61) fastened to the upper end of the concave cavity (27).

The method according to claim 1,
The upper valve (60) and the lower valve (61)
A poppet valve 65 vertically moving in contact with the piston 50;
A spring 64 coupled between the poppet valve 65 and the valve cap 62 and returning the poppet valve 65 to its original position;
A housing 63b connected to the intake pipe I and the exhaust pipe E while accommodating the spring;
A valve cap 62a for fixing the spring 64 and the housing 63a; Including,
Wherein the housing (63a) has two channels connecting the intake pipe (I) and the exhaust pipe (E).

The method according to claim 1,
The conduit connecting the valve housing 40 and the upper valve 61 to the lower valve 61 comprises only the intake pipe I and the discharge pipe E,
Characterized in that a hole is provided at any one of a side of the cylinder (10) connected to the discharge pipe (E) or a side of the valve housing (40) to discharge the compressed air remaining in the discharge pipe and the closed space to the outside. .

The method according to claim 1,
The base (20)
A circular liner 28 for guiding the piston rod 51;
Further comprising at least one oil reservoir (29) on one side of the inner side of the liner (28).

The method according to claim 4,
The oil reservoir (29)
And is formed to have a structure capable of accommodating the sleeve length and thickness to be additionally inserted.