VACUUM MACHINE, COMPRESSOR, AND PISTON

Abstract

A vacuum machine includes: a crankcase; a cylinder body fixed to the crankcase; a cylinder head fixed to a distal end of the cylinder body; and a piston reciprocating within the cylinder body, wherein the piston includes: a piston rod; a piston head fixed to a distal end of the piston rod and defining a chamber in cooperation with the cylinder body and the cylinder head; and a check valve arranged within a space formed between the piston rod and the piston head, the piston rod and the piston head each includes a through-hole communicating with the space, and the check valve is elastically deformable within the space so as to open and close one of the through holes of the piston rod and the piston head.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2014-171862, filed on Aug. 26, 2014, and the prior Japanese Patent Application No. 2014-171875, filed on Aug. 26, 2014, the entire contents of which are incorporated herein by reference.

BACKGROUND

(i) Technical Field

The present invention relates to a vacuum machine, a compressor, and a piston.

(ii) Related Art

There are known a vacuum machine and a compressor in which a piston reciprocates. In some cases, a distal end of the piston is formed with a through-hole, and a check valve opening and closing this through-hole is fixed to a piston. This check valve is repeatedly and elastically deformed to open and close the through-hole in conjunction with the reciprocation of the piston. Japanese Patent Application Publication No. 2008-95700 discloses a related device.

When such a check valve is greatly elastically deformed repeatedly, the durability of the check valve might deteriorate. Also, when the check valve is deformed greatly, it might be plastically deformed to exceed its elastic limit, so that the through-hole cannot be closed adequately.

SUMMARY

According to an aspect of the present invention, there is provided a vacuum machine including: a crankcase; a cylinder body fixed to the crankcase; a cylinder head fixed to a distal end of the cylinder body; and a piston reciprocating within the cylinder body, wherein the piston includes: a piston rod; a piston head fixed to a distal end of the piston rod and defining a chamber in cooperation with the cylinder body and the cylinder head; and a check valve arranged within a space formed between the piston rod and the piston head, the piston rod and the piston head each includes a through-hole communicating with the space, and the check valve is elastically deformable within the space so as to open and close one of the through holes of the piston rod and the piston head.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a vacuum machine;

FIG. 2 is a side view of the vacuum machine;

FIG. 3 is a rear view of the vacuum machine;

FIG. 4 is a partial enlarged view of FIG. 3;

FIG. 5 is a partially sectional view of a vacuum machine according to a comparative example;

FIG. 6 is front view of a compressor;

FIG. 7 is a rear view of the compressor;

FIG. 8 is a partially enlarged view of FIG. 7; and

FIG. 9 is a partially sectional view of a compressor according to a comparative example.

DETAILED DESCRIPTION

FIGS. 1, 2, and 3 are front, side, and rear views of a vacuum machine A, respectively. Additionally, FIGS. 1 and 3 illustrate a partial section. The vacuum machine A includes: four cylinders 10a to 10d; a crankcase 20 to which the four cylinders 10a to 10d are fixed; and a motor M arranged on an upper portion of the crankcase 20. The cylinders 10a to 10d are fixed around the crankcase 20. The cylinder 10a includes: a cylinder body 12a fixed to the crankcase 20; and a cylinder head 15a fixed to the cylinder body 12a. A partition plate 14a intervenes between the cylinder body 12a and the cylinder head 15a. Likewise, the cylinders 10b to 10d include cylinder bodies 12b to 12d and cylinder heads 15b to 15d, respectively. Between the cylinder bodies 12b to 12d and the cylinder heads 15b to 15d, partition plates 14b to 14d intervene, respectively. The partition plates 14a to 14d are examples of partition wall portions. The cylinder 10a and the like and the crankcase 20 are made of metal such as aluminum with good heat radiation. A nozzle N is fixed to the crankcase 20. The nozzle N exhausts air introduced into the crankcase 20 to the outside. Also, apertures Hal and Hat are provided in the cylinder head 15a. Likewise, apertures Hb1, Hb2, Hc1, Hc2, Hd1, and Hd2 are provided in the cylinder heads 15b to 15d, respectively.

The motor M illustrated in FIG. 2 includes coils not illustrated, a rotor 40, a stator not illustrated, and a printed circuit board PB. The stator is fixed to the crankcase 20. Around the stator, plural coils are wound. The coils are electrically connected to the printed circuit board PB. The stator is excited by energizing the coils. The rotor 40 includes a rotational shaft 42, a yoke 44, and one or more permanent magnets not illustrated. The rotational shaft 42 is rotatably supported by plural bearings arranged within the crankcase 20. The yoke 44 is fixed to the rotational shaft 42, and the yoke 44 rotates with the rotational shaft 42. The yoke 44 has a substantially cylindrical shape, and is made of metal. One or more plural permanent magnets are fixed to an internal circumferential surface of the yoke 44. The permanent magnet faces an outer circumferential surface of the stator. The stator is excited by energizing the coils. Thus, the magnetic attractive force and the magnetic repulsive force exert between the permanent magnet and the stator. This magnetic force causes the rotor 40 to rotate. Thus, the motor M is a motor of an outer rotor type in which the rotor 40 rotates.

A fan F is fixed to the yoke 44 of the rotor 40, and rotates with the rotor 40. Thus, the crankcase 20 and the cylinders 10a to 10d are cooled. Also, an increase in temperature depending on friction of moveable portions can be suppressed.

Next, the internal structure of the cylinder 10a will be described. As illustrated in FIG. 3, the cylinder body 12a is fixed to an outer peripheral wall of the crankcase 20 to communicate with a hole formed in the outer peripheral wall of the crankcase 20. Also, the cylinder head 15a is fixed to a distal end of the cylinder body 12a through the partition plate 14a. A chamber 13a is formed in the cylinder body 12a. The chamber 13a is defined by the cylinder body 12a, a distal end of the piston Pa, and the partition plate 14a. The piston Pa reciprocates in conjunction with the rotation of the motor M, so a capacity of the chamber 13a increases and decreases. A proximal end of the piston Pa is located within the crankcase 20, and is coupled with the rotational shaft 42 receiving rotary power through a bearing from the motor M. Specifically, the proximal end of the piston Pa is coupled at the eccentric position with respect to the central position of the rotational shaft 42, and the piston Pa reciprocates in conjunction with the one-way rotation of the rotational shaft 42. Pistons not illustrated and moving within the other cylinders 10b to 10d are provided therewithin, respectively. As for these pistons, positional phases are shifted at intervals of 90 degrees. These pistons reciprocate to introduce air into the cylinders 10a to 10d and the crankcase 20 through the aperture Ha1, Hb1, Hc1, and Hd1, which exhausts air from the nozzle N.

Next, the inner structure of the cylinder 10a will be described in detail. FIG. 4 is a partially enlarged view of FIG. 3. The cylinder head 15a includes: rooms 18a and 19a partitioned from each other; and the apertures Hal and Ha2 respectively communicating with the rooms 18a and 19a. The partition plate 14a is formed with a hole portion 16a communicating the room 18a with the chamber 13a. Note that the partition plate 14a is not formed with a through-hole communicating the room 19a and the chamber 13a. However, the through-hole communicating the room 19a with the chamber 13a may be formed and sealed.

A check valve V1 is fixed to the partition plate 14a. The check valve V1 allows air to flow into the chamber 13a through the hole portion 16a from the room 18a, but restricts air from flowing reversely. The check valve V1 is fixed to an inner surface of the partition plate 14a facing the piston head 25a by a screw S1. A proximal end of the check valve V1 is fixed to the partition plate 14a by the screw S1, a distal end of the check valve V1 is a free end, and the check valve V1 is elastically deformed to open and close the hole portion 16a. The check valve V1 is elastically deformed by a difference in inner pressure between the chamber 13a and the room 18a, so the hole portion 16a is opened and closed. The check valve Vi is arranged within the chamber 13a. The check valve V1 is made of metal such as a stainless steel, but is not limited to this.

The piston Pa includes: a piston rod 21a having a proximal end coupled with the rotational shaft 42; and a piston head 25a fixed to a distal end of the piston rod 21a by a screw not illustrated. A sealing ring C is sandwiched between the piston rod 21a and the piston head 25a. The sealing ring C seals between the piston Pa and an inner side surface of the cylinder body 12a, and is made of material such as fluoric resin with a good self-lubrication property.

A space SP is formed between the distal end of the piston rod 21a and the piston head 25a.

Specifically, a recess portion 23a is formed in the distal end of the piston rod 21a, and a stepped portion 24a is formed around the recess portion 23a. The piston head 25a is fitted into and fixed to the stepped portion 24a. A through-hole 26a communicating with the space SP is formed in the piston head 25a. A through-hole 22a communicating with the space SP is formed in the piston rod 21a.

A check valve V2 is fixed to an inner surface, of the piston head 25a facing the recess portion 23a of the piston rod 21a, by a screw S2. The screw S2 is an example of a fixation member. A proximal end of the check valve V2 is fixed to the piston head 25a by the screw S2, a distal end of the check valve V2 is a free end, and the check valve V2 is elastically deformed to open and close the through-hole 26a. The check valve V2 is elastically deformed by a difference in inner pressure between the chamber 13a and the crankcase 20, so the through-hole 26a is opened and closed. The check valve V2 is provided within the space SP and is elastically deformable therewithin. The check valve V2 permits air to flow into the crankcase 20 through the through-hole 26a, the space SP, and the through-hole 22a from the chamber 13a, but restricts air from reversely flowing. The check valve V2 is made of metal such as stainless steel, but is not limited to this. The check valve V2 is a member that has a plate shape having a certain thickness so as to be elastically deformable.

When the reciprocation of the piston Pa causes the capacity of the chamber 13a to increase from the minimum to the maximum, air is introduced into the room 18a through the aperture Ha1 from the outside, and the distal end of the check valve V1 is elastically deformed to be bent away from the hole portion 16a, which opens the hole portion 16a. Thus, air is introduced into the chamber 13a. When the capacity of the chamber 13a decreases from the maximum to the minimum, the distal end of the check valve V2 is elastically deformed to be bent away from the through-hole 26a and opens the through-hole 26a, which introduces air from the chamber 13a to the crankcase 20 through the through-hole 26a, the space SP, and the through-hole 22a. Additionally, at this time, the check valve V1 is kept closing the hole portion 16a by the inner pressure of the chamber 13a. In this way, air is introduced into the crankcase 20 through the chamber 13a from the outside by the reciprocation of the piston Pa. Note that the pistons respectively arranged within the cylinders 10b to 10d have the similar structure. Thus, air is introduced in the crankcase 20 from the outside by the reciprocation of these pistons.

As illustrated in FIG. 4, the check valve V2 is arranged between the distal end of the piston rod 21a and the piston head 25a. Thus, when the distal end of the check valve V2 is elastically deformed to be bent away from the through-hole 26a, the distal end of the check valve V2 abuts with a bottom surface of the recess portion 23a, so that the check valve V2 is restricted from being further elastically deformed. Thus, the maximum amount of the elastic deformation of the check valve V2 is restricted to a certain amount. For example, when the great elastic deformation is repeated in such a check valve V2, the durability of the check valve might deteriorates. Also, when the check valve is deformed greatly, it might be plastically deformed to exceed its elastic limit, so that the through-hole cannot be closed adequately. Thus, the performance of the check valve might deteriorate. In the present embodiment, the check valve V2 is arranged between the piston rod 21a and the piston head 25a, and the elastic deformation amount is restricted by the piston rod 21a. This can suppress the deterioration in the performance of the check valve V2 caused by a too large amount of the elastic deformation.

Also, the through-hole 22a releases the screw S2 fixing the check valve V2 to the piston head 25a. Specifically, the through-hole 22a is formed coaxially with the screw S2 so as not to interfere with a head portion of the screw S2 protruding to the space SP. Thus, regardless of the protruding amount of the screw S2, the thickness of the space SP can be designed. Therefore, for example, the thickness of the space SP can be designed smaller than that of the head portion of the screw S2, and the total thickness of the distal end of the piston rod 21a and the piston head 25a can be designed small.

Also, the through-hole 26a is formed a such a position as to release the head portion of the screw S1 protruding into the chamber 13a. Therefore, the screw S1 avoids interfering with the piston head 25a. Thus, even if the head portion of the screw S1 protrudes into the chamber 13a, the through-hole 26a releases the head portion of the screw S1, so the minimum of the capacity of the chamber 13a can be small as much as possible, thereby ensuring the ratio of the maximum to the minimum of the capacity of the chamber 13a. This can further introduce air into the crankcase 20. The screw S1 is an example of a cylinder side fixation member.

Next, a description will be given of a vacuum machine X according to a comparative example having structure different from the vacuum machine A. FIG. 5 is a partially sectional view of the vacuum machine X according to the comparative example, and FIG. 5 corresponds to FIG. 4. Additionally, similar components are designated with similar reference numerals and a duplicated description of those components will be omitted. The cylinder 10x includes a cylinder body 12x, a partition plate 14x, a cylinder head 15x. A check valve V1x, arranged within a room 18x and fixed to an outer surface of the partition plate 14x by a screw not illustrated, permits air to pass to a chamber 13x through a hole portion 16x from the room 18x, but restricts air from passing reversely. The check valve V2x, arranged within the chamber 13x and fixed to an inner surface of the partition plate 14x by a screw not illustrated, permits air to pass to a room 19x through a hole portion 17x from chamber 13x, but restricts air from passing reversely. A piston Px includes a piston rod 21x, a piston head 25x, and a sealing ring Cx. A space is not provided between the piston rod 21x and the piston head 25x.

Air is introduced into the chamber 13x through an aperture Hx1, the room 18x, and the hole portion 16x by the reciprocation of the piston Px, and air is exhausted outside from the chamber 13x through the hole portion 17x, the room 19x, and an aperture Hx2. In the vacuum machine X, air is not introduced into the crankcase 20x. Thus, most of the flowing passage of air is the rooms 18x and 19x of the cylinder head 15x located at the outer side of the vacuum machine X. For this reason, there is a certain limit to a decrease in leak of sound of air flowing. In the vacuum machine A according to the present embodiment, air flows through the crankcase 20 as illustrated in FIG. 4. This can suppress sound of air flowing through the crankcase 20 from being leaked, and can suppress the noise. Also, in the vacuum machine A according to the present embodiment, air flows from the narrow space chamber 13a to the wide space crankcase 20, so the noise is suppressed by the operation similar to car mufflers.

Also, in a case where the vacuum machine X according to the comparative example has plural pairs of the cylinder body, the cylinder head, and the piston, it is considered that a passage for meeting air exhausted from the cylinder heads is provided outside the crankcase 20x. However, in the vacuum machine A according to the present embodiment, air introduced from the cylinder heads 15a to 15d are met within the crankcase 20. For this reason, a special passage for meeting air is not needed. Thus, as for the vacuum machine A according to the present embodiment, an increase in the number of parts is suppressed, and an increase in size of the device is also suppressed.

Also, in the vacuum machine X according to the comparative example, air does not flow in the crankcase 20x. In the vacuum machine A according to the present embodiment, air flows through the crankcase 20 and is exhausted outside from the nozzle N. Thus, the crankcase 20 can be cooled, and the heat degradation in parts of the crankcase 20 can be suppressed.

Next, a compressor A′ according to the present embodiment will be described. FIGS. 6 and 7 are front and rear views of the compressor A′, respectively. FIG. 6 corresponds to FIG. 1, and FIG. 7 corresponds to FIG. 3. Additionally, similar components are designated with similar reference numerals and a duplicated description of those components will be omitted. Unlike the vacuum machine A, in the compressor A′, air is introduced into the crankcase 20 through the nozzle N.

FIG. 8 is a partially enlarged view of FIG. 7. A partition plate 14a′ is formed with a hole portion 16a′ communicating the room 19a with the chamber 13a. The partition plate 14a′ is not formed with a through-hole communicating the room 18a with the chamber 13a, but may be formed with a through-hole communicating the room 18a with the chamber 13a, and this through-hole may be sealed.

A check valve V1′ is fixed to the partition plate 14a′. The check valve V1′ permits air to flow to the room 19a through the hole portion 16a′ from the chamber 13a, but restrict air from flowing reversely. The check valve V1′ is fixed to an outer surface, of the partition plate 14a′ facing the cylinder head 15a, by a screw S1′. The screw S1′ and the hole portion 16a′ are arranged in the central axis direction of the rotational shaft 42. Thus, the check valve V1′ is fixed to the partition plate 14a′ in such a posture that the central axis direction of the rotational shaft 42 is the longer direction. A proximal end of the check valve V1′ is fixed to the partition plate 14a′ by the screw S1′, a distal end of the check valve V1′ is a free end, and the check valve V1′ is elastically deformed so as to open and close the hole portion 16a′. The check valve V1′ is elastically deformed by a difference in inner pressure between the chamber 13a and a room 19a, so the hole portion 16a′ is opened and closed. The check valve V1′ is provided within the room 19a.

A piston Pa′ includes: a piston rod 21a′; a piston head 25a′ fixed to a distal end of the piston rod 21a′ by a screw not illustrated; and a seal ring C′ sandwiched between the piston rod 21a′ and the piston head 25a′. The check valve V2′ is fixed to a bottom surface, of the recess portion 23a of the piston rod 21a′ facing the piston head 25a′, by a screw S2′. The screw S2′ is an example of a fixation member. A proximal end of the check valve V2′ is fixed to the piston rod 21a′ by the screw S2′, a distal end of the check valve V2′ is a free end, and the check valve V2′ is elastically deformed to open and close the through-hole 22a. The check valve V2′ is elastically deformed by a difference in inner pressure between the chamber 13a and the crankcase 20, so that through-hole 22a is opened and closed. The check valve V2′ is provided and is elastically deformable within the space SP. The check valve V2′ permits air to flow into the crankcase 20 through the through-hole 26a, the space SP, and the through-hole 22a from the chamber 13a, but restrict air from flowing reversely.

When the capacity of the chamber 13a is increased from the minimum by the reciprocation of the piston Pa′, the distal end of the check valve V2′ is elastically deformed to be bent away from the through-hole 22a, which opens the through-hole 22a. Thus, air introduced into the crankcase 20 through the nozzle N is introduced into the chamber 13a through the through-hole 22a, the space SP, and the through-hole 26a. When the capacity of the chamber 13a decreases from the maximum, the distal end of the check valve V1′ is elastically deformed to be bent away from the hole portion 16a′, which opens the hole portion 16a′. Thus, air is introduced into the room 19a from the chamber 13a, and is exhausted from the aperture Ha2.

When the distal end of the check valve V2′ is elastically deformed to be bent away from the through-hole 22a, the distal end of the check valve V2′ abuts with an inner surface of the piston head 25a′, so that the check valve V2′ is restricted from being further elastically deformed. Thus, the maximum amount of the elastic deformation of the check valve V2′ is restricted to a certain amount. This can suppress the deterioration in the performance of the check valve V2′ caused by a too large amount of the elastic deformation.

Also, the through-hole 26a releases the screw S2′ fixing the check valve V2′. Specifically, the through-hole 26a is formed coaxially with the screw S2′ so as not to interfere with a head portion of the screw S2′ protruding to the space SP. Therefore, for example, the thickness of the space SP can be designed smaller than that of the head portion of the screw S2′, and the total thickness of the distal end of the piston rod 21a′ and the piston head 25a′ can be designed small.

Also, the through-hole 26a is formed at such a position as to release a lower end portion of the screw S1′ protruding into the chamber 13a in accordance with the reciprocation of the piston Pa′. Therefore, the screw S1′ avoids interfering with the piston head 25a. Thus, the minimum of the capacity of the chamber 13a can be small as much as possible, thereby exhausting the large amount of air from the crankcase 20. The screw S1′ is an example of a cylinder side fixation member.

Next, a description will be given of a compressor X′ according to a comparative example having structure different from the compressor A′. FIG. 9 is a partially sectional view of the compressor X′ according to the comparative example. FIG. 9 is the partially sectional view of a side view of the compressor X′, and illustrates the compressor X′ when viewed along the cross section parallel with a rotational shaft. An upper portion of the compressor X′ is located at the left side of FIG. 9, and the bottom side is located at the right side of FIG. 9. Additionally, similar components are designated with similar reference numerals and a duplicated description of those components will be omitted. A cylinder 10x′ includes a cylinder body 12x′, a partition plate 14x′, and a cylinder head 15x′. A check valve V1x′, arranged within a room 19x′ and fixed to an outer surface of the partition plate 14x′ by a screw not illustrated, permits air to pass to a chamber 19x′ through a hole portion 17x′ from the room 13x′, but restricts air from passing reversely. A check valve V2x′, arranged within the chamber 13x′ and fixed to an outer surface of the piston head 25x′ by a screw S2x′, permits air to pass to a chamber 13x′ from a crankcase 20x′, but restricts air from flowing reversely. The piston Px′ includes a piston rod 21x′,a piston head 25x′, and a seal ring Cx′. The space is not provided between the piston rod 21x′ and the piston head 25x′. Through-holes 22x′ are 26x′ directly communicate with each other.

Air is introduced into the chamber 13x′ through the through-holes 22x′ and 26x′ from the crankcase 20x′ by the reciprocation of the piston Px′, and air is exhausted outside from an aperture Hx2′ through the hole portion 17x′ and the room 19x′. As illustrated in FIG. 9, the check valve V2x′ is fixed to the outer surface of the piston head 25x′. Thus, when a capacity of the chamber 13x′ increases, a distal end of the check valve V2x′ is elastically deformed to be bent away from the through-hole 26x′. At this time, the amount of the elastic deformation of the check valve V2x′ cannot be restricted. Thus, the amount of the elastic of deformation of the check valve V2x′ might be large, and the performance might deteriorate.

Also, the check valve V2x′ is elastically deformed such that its distal end abuts with an inner surface of the partition plate 14x′, so that contact noise might be made. In particular, when the piston Px′ reciprocates at high speed, the amount of the elastic deformation of the check valve V2x′ increases and the distal end of the check valve V2x′ abuts with the inner surface of the partition plate 14x′ in accordance with the reciprocation of the piston Px′, which might increases the noise. In the compressor A′ according to the present embodiment, the maximum amount of the elastic deformation of the check valve V2′ is restricted to be a certain amount, which can also suppress an increase in the contact noise of the piston head 25a′ and the check valve V2′.

Also, the check valve V2x′ is fixed to the outer surface of the piston head 25x′ facing the inner surface of the partition plate 14x′. Therefore, in consideration of a position, a size, and a shape of the check valve V2x′, a shape of an inner surface of the partition plate 14x′ facing the check valve V2x′ has to be designed. In contrast, in the compressor A′ according to the present embodiment, the check valve V2′ is arranged between the piston head 25a′ and the piston rod 21a′, so the check valve V2′ does not abut with the partition plate 14a′. Thus, regardless of a position, a size, and a shape of the check valve V2′, the shape of the inner surface of the partition plate 14a′ can be designed. Accordingly, the freedom degree of the design of the partition plate 14a′ improves.

While the exemplary embodiments of the present invention have been illustrated in detail, the present invention is not limited to the above-mentioned embodiments, and other embodiments, variations and modifications may be made without departing from the scope of the present invention.

The vacuum machine A and the compressor A′ according to the present embodiment each has four pairs of the cylinders 10a to 10d and pistons, but are not limited to these. The vacuum machine and the compressor each may have only one pair, two pairs, or three pairs of the cylinders and pistons, and may have five or more pairs of the cylinders and pistons.

The vacuum machine A according to the present embodiment functions as a compressor, when an object product is connected to the nozzle N that exhausts air. The compressor A′ according to the present embodiment functions as a vacuum machine, when an object product is connected to the nozzle N that intakes air.

Note that, in the present embodiment, subject matters of additional notes to be described later are supported. The subject matters of the additional notes will be explained below.

There is known a vacuum machine in which a capacity of a chamber increases depending on reciprocation of a piston within a cylinder body fixed to a crankcase and in which air is sent from an intake room to an exhaust room through this chamber. Japanese Patent Application Publication No. 2008-95700 discloses a related device.

The cylinder head is arranged in the outside of the crankcase, and air flows to the exhaust room through the chamber from the intake room in the cylinder head. In this way, a flowing passage of air is mainly located at the outside of the crankcase, so that there is a certain limit to a decrease in leak of sound of air flowing.

According to an aspect of following additional notes, there are provided a vacuum machine and a compressor in which noise is restricted.

(additional note 1)

1. A vacuum machine or a compressor comprising:

a crankcase;

a cylinder body fixed to the crankcase;

a cylinder head fixed to a distal end of the cylinder body; and

a piston reciprocating within the cylinder body,

wherein

the piston includes:

• • a piston rod; a piston head fixed to a distal end of the piston rod and defining a chamber in cooperation with the cylinder body and the cylinder head; and
  • a check valve arranged within a space formed between the piston rod and the piston head,

the piston rod and the piston head each includes a through-hole communicating with the space, and

the check valve is elastically deformed within the space so as to open and close the through-hole of the piston rod or the piston head, permits air to flow from one of the chamber and the crankcase to the other one of the chamber and the crankcase through the through-holes of the piston rod and the piston head and the space, and restrict air from flowing to the other one of the chamber and the crankcase from the one of the chamber and the crankcase.

(additional note 2)

2. The vacuum machine or the compressor of additional note 1 comprising a plural pairs of the cylinder body, the cylinder head, and the piston.

Claims

1. A vacuum machine comprising: a crankcase;a cylinder body fixed to the crankcase;a cylinder head fixed to a distal end of the cylinder body;and a piston reciprocating within the cylinder body,wherein the piston includes: a piston rod; a piston head fixed to a distal end of the piston rod and defining a chamber in cooperation with the cylinder body and the cylinder head; anda check valve arranged within a space formed between the piston rod and the piston head,the piston rod and the piston head each includes a through-hole communicating with the space, andthe check valve is elastically deformable within the space so as to open and close one of the through holes of the piston rod and the piston head.

2. The vacuum machine of claim 1, wherein the check valve abuts with the one of the piston rod and the piston head to close the one of the through holes of the piston rod and the piston head, and is elastically deformed away from the one of the through holes of the piston rod and the piston head and closer to the other one of the through holes of the piston rod and the piston head to open the one of the through holes of the piston rod and the piston head.

3. The vacuum machine of claim 1, wherein the check valve is fixed to the one of the piston rod and the piston head by a fixation member, andthe other one of the through-holes of the piston rod and the piston head releases the fixation member.

4. The vacuum machine of claim 1, wherein the cylinder head includes a partition wall portion defining the chamber in cooperation with the piston head,the partition wall portion is formed with a communication hole communicating with the chamber, an opening and closing member opening and closing the communication hole being fixed to the partition wall portion by a cylinder side fixation member, andthe through-hole of the piston head releases the cylinder side fixation member projecting in the chamber in accordance with reciprocation of the piston head.

5. A compressor comprising: a crankcase;a cylinder body fixed to the crankcase;a cylinder head fixed to a distal end of the cylinder body;and a piston reciprocating within the cylinder body,wherein the piston includes: a piston rod; a piston head fixed to a distal end of the piston rod and defining a chamber in cooperation with the cylinder body and the cylinder head; anda check valve arranged within a space formed between the piston rod and the piston head,the piston rod and the piston head each includes a through-hole communicating with the space, andthe check valve is elastically deformable within the space so as to open and close one of the through holes of the piston rod and the piston head.

6. The compressor of claim 5, wherein the check valve abuts with the one of the piston rod and the piston head to close the one of the through holes of the piston rod and the piston head, and is elastically deformed away from the one of the through holes of the piston rod and the piston head and closer to the other one of the through holes of the piston rod and the piston head to open the one of the through holes of the piston rod and the piston head.

7. The compressor of claim 5, wherein the check valve is fixed to the one of the piston rod and the piston head by a fixation member, andthe other one of the through-holes of the piston rod and the piston head releases the fixation member.

8. The compressor of claim 5, wherein the cylinder head includes a partition wall portion defining the chamber in cooperation with the piston head,the partition wall portion is formed with a communication hole communicating with the chamber, an opening and closing member opening and closing the communication hole being fixed to the partition wall portion by a cylinder side fixation member, andthe through-hole of the piston head releases the cylinder side fixation member projecting in the chamber in accordance with reciprocation of the piston head.

9. A piston comprising: a piston rod;a piston head fixed to a distal end of the piston rod; anda check valve arranged within a space formed between the piston rod and the piston head,wherein the piston rod and the piston head each includes a through-hole communicating with the space, andthe check valve is elastically deformable within the space so as to open and close one of the through holes of the piston rod and the piston head.