JPH09137777A - Reciprocating compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a problem such as abrasion of a push rod so as to improve durability and the service life by arranging a maximum stroke restricting part for restricting the maximum stroke of an unload piston by abutting on the bottom part side of an unload cylinder on the unload piston of an unload mechanism. SOLUTION: In an unload mechanism 32, air pressure from an outside is supplied into an air chamber 39 so as to push-move an unload piston 35, and the abutting surface 37 thereof abuts on the bottom surface 33B in an installing part 33 so as to restrict the displacement of the unload piston 35. The valve plate 15 of an intake valve is push-moved by the projection part 40A of a push rod 40 so as to hold the intake valve in an opening condition. The unload piston 35 consists of a piston part 36 and a large diameter part 37, the outer diameter of the large diameter part 37 is enlarged more than the inner diameter of the cylinder part 34A of the cover body 34, and also the lower side surface of the large diameter part 37 is formed as an abutting surface 37B, and thereby, the maximum stroke of the unload piston 35 is restricted so as to reduce the surface pressure at the time of contact.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating compressor suitably used, for example, as an air compressor.
The present invention relates to a reciprocating compressor having an unload mechanism for controlling a load operation and an unload operation.

[0002]

2. Description of the Related Art An air compressor will be described as an example of a reciprocating compressor according to the prior art with reference to FIGS.

[0003] In the drawing, reference numeral 1 denotes a cylinder formed in a substantially cylindrical shape, and an upper end 1A of the cylinder 1 has a valve seat plate 3 to be described later.
The cylinder head 7 is fixed by bolts or the like (not shown).

Further, the upper end 1A of the cylinder 1 has
A step portion 2 as a stopper portion is formed on the inner peripheral side thereof, and the step portion 2 is configured to regulate the valve opening degree of a suction valve 13 described later.

Reference numeral 3 denotes a valve seat plate provided on the upper end portion 1A of the cylinder 1. The valve seat plate 3 is formed as a substantially rectangular flat plate and is compressed into the cylinder 1 together with a piston 11 described later. It defines chamber 4. The valve seat plate 3 has a compression chamber 4
A suction hole 5 and a discharge hole 6 are formed so as to communicate with
As shown in FIG. 8, the suction hole 5 has a substantially oval shape or “8”.
It is formed as a V-shaped through hole. A pair of receiving portions 5 projecting inward in the radial direction are provided at the center of the suction hole 5.
A and 5A are provided, and each receiving portion 5A regulates the maximum stroke of the unload piston 21 described later.

Reference numeral 7 denotes a cylinder head mounted on the cylinder 1 via a valve seat plate 3, and the cylinder head 7 has a suction chamber 8 and a discharge chamber 9 between the valve seat plate 3 and the cylinder head 7. A partition wall 7A is formed to define the and. A suction port 7B and a discharge port (not shown) are formed in the cylinder head 7, the suction port 7B communicates with the suction hole 5 through the suction chamber 8, and the discharge port through the discharge chamber 9. It communicates with the discharge hole 6. Further, a mounting portion 10 to which an unload mechanism 19 described later is mounted is formed on the suction chamber 8 side.

Here, the mounting portion 10 is located above the suction hole 5 and is provided in the cylinder head 7 in a cylindrical shape with a bottom. The bottom portion of the mounting portion 10 is sucked so as to communicate with the suction chamber 8. An insertion hole 10A is formed above the hole 5.

Reference numeral 11 denotes a piston slidably fitted in the cylinder 1. The piston 11 is connected to a crankshaft (not shown) via a connecting rod 12, and the crankshaft is connected to an electric motor or the like. By being rotated by the drive source, the piston 11 reciprocates in the cylinder 1 via the piston ring 11A and the rider ring 11B. Then, in the suction stroke of the piston 11, the suction valve 13 is opened and the suction chamber 8
Side air is sucked into the compression chamber 4, the suction valve 13 is closed in the discharge stroke (compression stroke), and the discharge valve 16 described later is opened, so that the compressed air flows from the compression chamber 4 into the discharge chamber 9. Is discharged.

Reference numeral 13 denotes a suction valve mounted on the lower surface side (compression chamber 4 side) of the valve seat plate 3 to open and close the suction hole, and the suction valve 13 has a short bolt 14 at the base end side thereof. Seat plate 3
The valve plate 15 is fixed to the lower surface of the valve plate and has a free end on the front end side. The valve plate 15 is formed of a thin plate having a spring property. The valve plate 15 of the suction valve 13 is the piston 1
1 reciprocates, separates from and seats on the lower surface of the valve seat plate 3,
Is connected to and cut off from the compression chamber 4 through the suction hole 5. Further, when the suction valve 13 is opened, the front end side of the valve plate 15 contacts the step portion 2 of the cylinder 1, so that the valve opening (lift amount) of the suction valve 13 is regulated.

Reference numeral 16 denotes a discharge chamber 9 for opening and closing the discharge hole 6.
The discharge valve is positioned inside and is attached to the upper surface side of the valve seat plate 3. The discharge valve 16 has a base end side with a bolt 17 or the like.
The valve plate 18 is fixedly attached to the discharge hole 6. The valve plate 18 has a free end and extends to the periphery of the discharge hole 6.

Reference numeral 19 denotes an unloading mechanism located above the suction hole 5 and attached to the mounting portion 10 of the cylinder head 7. The unloading mechanism 19 is, as shown in FIG. The unload piston 21 and the push rod 25 are included.

Reference numeral 20 denotes a lid body screwed to the attachment portion 10 in order to cover the upper opening of the attachment portion 10.
Is composed of a cylindrical cylinder portion 20A forming an unload cylinder together with the mounting portion 10 and a plate-shaped lid portion 20B formed on the upper side of the cylinder portion 20A.
A connection hole 20C for connecting an air conduit (not shown) is provided at the center of the.

Reference numeral 21 denotes an unload piston arranged in the mounting portion 10, and the unload piston 21 is slidably fitted in the cylinder portion 20A of the lid body 20 and inside the cylinder portion 20A. An air chamber 22 is defined between it and the lid portion 20B. An annular recess 21A is formed on the outer peripheral side of the unload piston 21, and an O-ring 23 that hermetically seals between the cylinder portion 20A and the unload piston 21 is mounted in the annular recess 21A. .

Reference numeral 24 designates the unload piston 21 and the air chamber 2
The urging spring 24 is always urged toward the second side. The urging spring 24 is formed of a coil spring and is arranged around the push rod 25. And the biasing spring 2
4, the upper end side is in contact with the unload piston 21, and the lower end side is in contact with the bottom side in the mounting portion 10.

Reference numeral 25 denotes a push rod integrally formed on one end side (lower end side) of the unload piston 21.
The push rod 25 is formed as a stepped rod,
The tip (lower end) side projects into the suction chamber 8 through the insertion hole 10A of the mounting portion 10. The tip end surface of the push rod 25 is in contact with the receiving portion 5A.
5A, a small-diameter convex portion 25B extending in the axial direction is integrally formed at the center of the corresponding contact surface 25A.

Here, the unload mechanism 19 supplies an air pressure (compressed air) into the air chamber 22 from an external compressed air source (not shown) through the air conduit or the like, thereby unloading the piston 21. Is pushed downward against the urging spring 24, and the contact surface 25A of the push rod 25 moves the suction hole 5
By contacting each of the receiving portions 5A, the stroke ends and the displacement of the unload piston 21 is regulated. Then, at this time, the convex portion 25 of the push rod 25
B forcibly pushes the valve plate 15 of the suction valve 13 toward the step portion 2 and holds the suction valve 13 in the open state, thereby continuing the unload operation of the compressor.

When the supply of the air pressure is stopped, the unload piston 21 is pushed back toward the air chamber 22 by the urging spring 24, and the convex portion 25B of the push rod 25 is formed.
Is pushed upward and separated from the valve plate 15, so that the valve plate 15 of the suction valve 13 can be seated on and seated on the valve seat plate 3.

Reference numerals 26 and 27 denote gaskets, which are mounted on the upper and lower surfaces of the valve seat plate 3 and serve as sealing members that hermetically seal between the cylinder head 7 and the cylinder 1.

In the air compressor of the prior art constructed as described above, the crankshaft is rotationally driven by the drive source (not shown) such as an electric motor during the load operation to reciprocate the piston 11 in the cylinder 1. External air is sucked in from the suction port 7B via, for example, an air filter (not shown), and this air flows from the suction chamber 8 into the compression chamber 4 via the suction hole 5 when the suction valve 13 is opened. Is sucked in. And
While the air in the compression chamber 4 is compressed by the piston 11,
The valve plate 18 of each discharge valve 16 is opened by pushing upward, and compressed air is discharged from each discharge hole 6 to the discharge chamber 9.

In this case, in the suction stroke in which the piston 11 reciprocates in the cylinder 1, the discharge valve 16 closes and the suction valve 1
3 is opened, the suction valve 13 is closed and the discharge valve 16 is opened in the discharge stroke, so that compressed air is sequentially discharged into the discharge chamber 9 according to the opening and closing of the discharge valve 16. , Is stored in an air tank (neither is shown) connected to the discharge port via an air conduit or the like.

[0021]

By the way, in the above-mentioned prior art, when the unloading mechanism 19 is operated during the unloading operation of the compressor, the contact surface 2 of the push rod 25 is changed.
Since 5A contacts the receiving portions 5A, 5A of the suction hole 5 to regulate the stroke end (maximum stroke) of the unload piston 21, the following problems occur.

That is, the suction hole 5 formed in the valve seat plate 3 is shown in FIG.
As shown in, when the contact surface 25A of the push rod 25 is in contact with each receiving portion 5A of the suction hole 5, the contact area between the two is very small.
The surface pressure at the time of contact increases, and the contact surface 25A of the push rod 25 and the like are quickly worn. Further, at this time, each receiving portion 5A of the valve seat plate 3 is also worn out, so that each receiving portion 5A
If the distance between them increases, in the worst case, the tip end side of the push rod 25 fits into the suction hole 5 and cannot be removed.

Further, since the receiving portions 5A, 5A are projectingly provided in the suction hole 5, the respective receiving portions 5A during the suction stroke of the compressor.
Becomes suction resistance, leading to a reduction in compression efficiency, and
Contact surface 25A of push rod 25 and receiving portions 5A, 5A
There is a problem that it is difficult to block the noise when and are in contact with each other.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention can reliably control the maximum stroke of the unload piston, and can solve the problems such as wear of the push rod and also have durability. It is an object of the present invention to provide a reciprocating compressor that can surely improve the life and the life and can significantly reduce noise, suction resistance, and the like.

[0025]

In order to solve the above-mentioned problems, the present invention provides a cylinder, a piston reciprocally provided in the cylinder, a piston mounted on the cylinder, and a suction chamber inside. A cylinder head having a discharge chamber formed therein, a suction valve for connecting and blocking the suction chamber of the cylinder head to and from the inside of the cylinder, and an unload provided on the cylinder head for forcibly opening the suction valve. It is applied to a reciprocating compressor composed of a mechanism.

The features of the configuration adopted by the present invention are as follows.
The unload mechanism includes an unload cylinder provided in the cylinder head in a cylindrical shape with a bottom, and an unload cylinder having an insertion hole communicating with the suction chamber on the bottom side, and slidably inserted into the unload cylinder. With the unloading piston fitted,
A push rod provided on the unload piston and protruding into the suction chamber through an insertion hole of the unload cylinder to push the suction valve at the tip side; and a unload cylinder provided on the unload cylinder. And a drive means for driving the unload piston in a cylinder, wherein the unload piston is provided with a maximum stroke regulating portion for regulating a maximum stroke of the unload piston by abutting on a bottom side of the unload cylinder. There is something.

With this configuration, the maximum stroke of the unload piston can be restricted on the bottom side of the unload cylinder, so that the contact area with the unload piston on the bottom side of the unload cylinder can be increased. Wear of the unload piston can be prevented by reducing the contact surface pressure.

[0028]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in the embodiment (hereinafter, referred to as an example) of the present invention, the same components as those of the above-described conventional technique are designated by the same reference numerals, and the description thereof will be omitted.

FIGS. 1 to 3 show a first embodiment of the present invention.

In the figure, reference numeral 31 denotes a suction hole formed in the valve seat plate 3, and although the suction hole 31 is formed in substantially the same manner as the suction hole 5 described in the prior art, the suction hole shown in FIG. The receiving portions 5A and the like of the hole 5 are eliminated, and the suction hole 31 is formed, for example, in an oval shape or a circular shape.

Reference numeral 32 denotes an unloading mechanism used in this embodiment. The unloading mechanism 32 is similar to the unloading mechanism 19 described in the prior art, and has a mounting portion 33 and a lid 3 which will be described later.
4, unload piston 35 and push rod 40
The unload piston 35 and the like of the unload mechanism 32 are located above the suction hole 31 and are mounted in the mounting portion 33 of the cylinder head 7.

Reference numeral 33 denotes a mounting portion integrally provided on the cylinder head 7. The mounting portion 33 is formed in a cylindrical shape having a bottom substantially like the mounting portion 10 described in the prior art, and the bottom side thereof will be described later. Insertion hole 33A into which the push rod 40 of FIG.
Are formed.

Reference numeral 34 denotes a lid body screwed to the attachment portion 33 so as to cover the upper opening of the attachment portion 33.
Comprises a cylindrical cylinder portion 34A that forms an unload cylinder together with the mounting portion 33, and a plate-shaped lid portion 34B formed on the upper side of the cylinder portion 34A.
A connection hole 34C for connecting an air conduit (not shown) is provided at the center of the.

Reference numeral 35 denotes an unload piston arranged in the mounting portion 33, and the unload piston 35 is
It is composed of a piston portion 36 slidably fitted in the cylinder portion 34A, and a large diameter portion 37 integrally formed on the lower end side (one end side) of the piston portion 36 via a small diameter connecting portion 36A. The large-diameter portion 37 is integrally formed at its upper end side with an annular flange portion 37A that projects outward in the radial direction. An annular recess 36B is formed on the outer peripheral side of the piston portion 36 of the unload piston 35, and an O-ring as a sealing member that hermetically seals between the cylinder portion 34A and the piston portion 36 inside the annular recess 36B. 38 is attached.

Here, the large diameter portion 37 of the unload piston 35 is formed in a stepped columnar shape having an outer diameter larger than the inner diameter of the cylinder portion 34A, and the flange portion 37A serves as a spring bearing for a biasing spring 41 described later, The upper surface is the cylinder part 3
It is possible to contact the lower end side of 4A. Also, the large diameter portion 3
As shown in FIG. 2, the lower side surface of 7 serves as an abutment surface 37B as a maximum stroke restriction portion formed in an annular shape around the base end side of the push rod 40, and the corresponding abutment surface 37B is the attachment portion 3B.
The maximum stroke (stroke end) of the unload piston 35 is regulated by abutting against the bottom surface 33B in the inside 3.

Reference numeral 39 denotes an air chamber located inside the cylinder portion 34A of the lid 34 and defined between the lid portion 34B and the piston portion 36. The air chamber 39 is the unload piston 35.
Of the unloading piston 35 by supplying air pressure from the connection hole 34C side of the lid 34.
Is urged downward against a biasing spring 41, which will be described later, as shown in FIG.

40 is one end side (lower end side) of the large diameter portion 37.
The push rod 40 is formed as a stepped rod, and the tip (lower end) side thereof projects into the suction chamber 8 through the insertion hole 33A of the mounting portion 33. A small-diameter convex portion 40A extending in the axial direction is integrally formed at the center of the tip end surface of the push rod 40.

Reference numeral 41 designates the unload piston 35 for the air chamber 3
9 shows a biasing spring constantly biased toward the 9 side, the biasing spring 41 being formed by a coil spring,
Is arranged around. The upper end of the biasing spring 41 is in contact with the flange portion 37A of the large diameter portion 37, and the lower end thereof is in contact with the bottom surface 33B in the mounting portion 33.

Here, the unloading mechanism 32 supplies an air pressure (compressed air) into the air chamber 39 from an external compressed air source (not shown) through the air conduit or the like, thereby unloading the piston 35. Is pressed downward against the urging spring 41, and the contact surface 37B of the unload piston 35 contacts the bottom surface 33B in the mounting portion 33, thereby becoming the stroke end and the unload piston 35 is displaced. Regulated. Then, at this time, the convex portion 40A of the push rod 40 forcibly pushes the valve plate 15 of the suction valve 13 toward the stepped portion 2 and holds the suction valve 13 in the open state, whereby the compressor is closed. Continue the unload operation of.

When the supply of the air pressure is stopped, the unload piston 35 is pushed back toward the air chamber 39 by the biasing spring 41, and the convex portion 40A of the push rod 40 is pushed.
Is pushed upward and separated from the valve plate 15, so that the valve plate 15 of the suction valve 13 can be seated on and seated on the valve seat plate 3.

The air compressor according to this embodiment is constructed as described above, and its basic compression operation is not different from that of the prior art.

However, according to this embodiment, the unloading mechanism 32 is provided in the cylinder head 7 in the shape of a cylinder with a bottom, and the mounting portion 3 is formed with the insertion hole 33A on the bottom side.
3, a lid 34 that constitutes an unload cylinder together with the mounting portion 33, an unload piston 35 whose upper end side is slidably fitted in a cylinder portion 34A of the lid 34,
A push rod 40 integrally formed as a stepped rod on the lower end side of the unload piston 35, and the lid 3
In the fourth cylinder portion 34A, there is an air chamber 39 as a driving means for driving the unload piston 35.

The unload piston 35 is composed of a piston portion 36 and a large diameter portion 37, the outer diameter of the large diameter portion 37 is made larger than the inner diameter of the cylinder portion 34A of the lid 34, and the large diameter portion is formed. An annular contact surface 37B that contacts the bottom surface 33B of the mounting portion 33 is provided on the lower side surface of 37 to limit the maximum stroke of the unload piston 35.

As a result, during the unloading operation of the compressor, the unloading mechanism 32 is operated and the unloading piston 35
At the end of the stroke (maximum stroke position), the contact surface 37B of the unload piston 35 becomes the bottom surface 33 of the mounting portion 33.
When abutting on B, the contact area between the two can be increased, and the surface pressure at the time of contact can be effectively reduced.

Therefore, according to the present embodiment, the tip end side of the push rod 40 is not worn as in the prior art, the wear of the unload piston 35 can be prevented, and the durability and life of the unload mechanism 32 as a whole are improved. The compressor can be extended, and the reliability of the compressor can be improved.

Further, the suction hole 3 is different from that of the prior art.
Since the shape of 1 can be simplified and the hole diameter can be increased, the suction resistance in the suction stroke of the compressor can be reduced and the compression efficiency can be increased. Further, the contact surface 37 that restricts the stroke of the unload piston 35
Since B and the like are stored in the mounting portion 33 of the cylinder head 7, the mounting portion 33 and the like effectively insulate noise from the unload piston 35 that occurs when the load operation and the unload operation are repeated. Therefore, noise can be surely reduced.

Next, FIG. 4 shows a second embodiment of the present invention. In this embodiment, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. To do. However, the feature of this embodiment resides in that the annular washer 51 is replaceably provided on the bottom surface 33B of the mounting portion 33.

Here, the washer 51 arranged on the bottom surface 33B of the mounting portion 33 comes into contact with the contact surface 37B of the unload piston 35 during the unloading operation of the compressor, so that the stroke end (maximum Stroke) is regulated.

Thus, in this embodiment having the above-described structure, it is possible to obtain substantially the same operation and effect as in the first embodiment. However, particularly in this embodiment, the unloading operation of the compressor is performed. Since the abutment surface 37B of the piston 35 abuts the washer 51, the maximum stroke of the unload piston 35 is restricted.
The wear of the contact surface 37B of No. 5 and the bottom surface 33B of the mounting portion 33 can be reliably prevented, the reliability and durability of the device can be improved, and a long-term operation can be compensated by replacing the washer 51. .

Next, FIG. 5 shows a third embodiment of the present invention. In this embodiment, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. To do. However, the feature of this embodiment resides in that a hollow hole 61 having a cylindrical shape with a bottom is bored from the central portion on the upper side of the unload piston 35 to the lower end side of the large diameter portion 37.

Thus, in this embodiment having the above-described structure, it is possible to obtain substantially the same effect as that of the first embodiment. However, in this embodiment, a hollow hole 61 is formed in the unload piston 35. Since it is provided, the unload piston 3
5 can be reduced in weight, and the contact surface 37B of the unloading piston 35 is attached to the mounting portion 3 at the start of unloading operation.
The impact at the time of contacting the bottom surface 33B of No. 3 can be reduced, and the contact surface 37B and the bottom surface 33B can be prevented from being worn, so that the life of the device can be extended.

In each of the above embodiments, the case where the driving means for driving the unload piston 35 is configured to supply the air pressure to the air chamber 39 has been described.
The present invention is not limited to this, for example, high pressure gas other than air may be supplied, and the unload piston 35
An electromagnetic actuator or the like may be adopted as the driving means of the above.

Further, in each of the above-mentioned embodiments, an air compressor has been described as an example of the reciprocating compressor, but the present invention is not limited to this, and for example, a compressor or a vacuum pump for compressing a gas other than air. It can also be widely applied to etc.

[0054]

As described in detail above, according to the present invention, the unloading mechanism is provided in the cylinder head in the shape of a bottomed cylinder, and has an insertion hole communicating with the suction chamber on the bottom side. An unload cylinder, an unload piston slidably inserted into the unload cylinder, and an insertion of the unload cylinder provided on the unload piston to push the suction valve at the tip side. The unload piston comprises a push rod projecting into the suction chamber through a hole, and a drive means provided in the unload cylinder and driving the unload piston in the unload cylinder. Since the maximum stroke regulating part that regulates the maximum stroke of the unload piston is provided by contacting the bottom side of the cylinder, It is possible to increase the contact area between the bottom side of the maximum stroke restricting portion and unload cylinder for regulating the maximum stroke of the unloading piston when,
The contact surface pressure can be reduced to prevent wear of the unload piston, and it is possible to prevent problems such as the push rod fitting into the suction hole, improving the reliability and durability of the device and extending its life. it can.

Further, for example, since the suction hole and the like can be enlarged, the suction resistance can be reduced and the compression efficiency can be improved. Since the maximum stroke regulating portion of the unload piston contacts the bottom side of the unload cylinder to regulate the maximum stroke of the unload piston, noise from the unload piston during repeated load operation and unload operation, etc. Can be shut off by an unload cylinder.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an unloading mechanism and the like of an air compressor according to a first embodiment of the present invention.

2 is an enlarged sectional view of the contact surface of the unload piston and the push rod in the direction of arrows II-II in FIG.

FIG. 3 is a vertical sectional view similar to FIG. 1, showing a state in which an unload mechanism is operated.

FIG. 4 is a vertical sectional view showing an unload mechanism and the like of an air compressor according to a second embodiment of the present invention.

FIG. 5 is a vertical sectional view showing an unload mechanism and the like of an air compressor according to a third embodiment of the present invention.

FIG. 6 is a vertical cross-sectional view showing an air compressor according to the related art.

7 is a longitudinal sectional view showing an enlarged unload mechanism and the like in FIG.

FIG. 8 is a sectional view taken in the direction of arrows VIII-VIII in FIG.

[Explanation of symbols]

 1 Cylinder 7 Cylinder Head 8 Suction Chamber 9 Discharge Chamber 11 Piston 13 Suction Valve 31 Suction Hole 32 Unload Mechanism 33 Mounting Part (Unload Cylinder) 33A Insertion Hole 33B Bottom 34 Lid 34A Cylinder 35 Unload Piston 36 Piston 37 Large diameter part 37B Abutment surface (maximum stroke restriction part) 39 Air chamber (driving means) 40 Push rod 41 Bias spring 51 Washer 61 Hollow hole

Claims (1)

[Claims] 1. A cylinder, a piston reciprocally provided in the cylinder, and mounted on the cylinder,
A cylinder head in which a suction chamber and a discharge chamber are formed, a suction valve for connecting and blocking the suction chamber of the cylinder head to the inside of the cylinder, and the cylinder head for forcibly opening the suction valve. In a reciprocating compressor composed of an unload mechanism provided, the unload mechanism is:
An unload cylinder provided in the cylinder head in the form of a cylinder with a bottom and having an insertion hole communicating with the suction chamber on the bottom side, and an unload piston slidably fitted in the unload cylinder. A push rod provided on the unload piston and protruding into the suction chamber through an insertion hole of the unload cylinder to push the suction valve on the tip side; A maximum stroke restricting portion for restricting the maximum stroke of the unload piston by contacting the unload piston with the bottom side of the unload cylinder, the drive means driving the unload piston in the unload cylinder. A reciprocating compressor characterized by being provided with.