JP2006220074A - Crank mechanism and compressor or pump using the crank mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crank mechanism improved in life and maintainability by compact structure and a compressor or a pump using the crank mechanism. <P>SOLUTION: This crank mechanism comprises a crankshaft 2, a crank web 3 fitted to at least one end of the crankshaft 2 and rotatable integrally with the crankshaft 2, a crank pin 4 fitted to the crank web 3 and revolving around the crank pin 2, a crank pin roller 5 rotatably fitted to the crank pin 4, a rectangular cross head 6 in which an oblong hole groove 8a in which the crank pin roller 5 is fitted is formed, and a frame 9 reciprocatingly and linearly guiding the cross head 6. The crank mechanism is characterized in that the revolving motion of the crank pin 4 and the reciprocating and linearly motion of the cross head 6 are converted to each other through the oblong hole groove 8a. The compressor or the pump uses the crank mechanism. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a crank mechanism and a compressor or pump using the crank mechanism.

In general, a crank mechanism is used as a mechanism for converting a rotary motion into a reciprocating motion. For example, as a crank mechanism used in a prime mover or the like, a crank shaft that conventionally performs a rotary motion as shown in FIGS. A configuration including 81, a connecting rod 82, and a crosshead 83 that reciprocates is widely used (Patent Document 1). Further, as shown in FIG. 8, the cross head 83 generally has an arc shape.
JP 2002-174131 A (FIG. 1)

However, the conventional method using a connecting rod requires high processing accuracy such as a large end portion and a small end portion, and not only the production cost is high, but also the maintenance cost due to uneven wear due to the structure is excessive, In addition, since the weight balance of the rotating part tends to be biased, the balance weight is increased and the inertia torque is increased. Therefore, there is a problem that the load acting on each member is increased and the life is shortened. Further, if the balance weight is excessive, there is a possibility that a large accident such as falling off of the balance weight may occur due to loosening or breakage of the bolt fixing the balance weight.
Furthermore, when rotating motion is converted into reciprocating motion via a connecting rod, precession occurs due to the structure, and the maximum speed of the reciprocating motion component is generated not before 90 ° of the crank angle. There is also a problem that the acceleration of the moving parts is increased and the valve timing is adversely affected.

  Therefore, the present invention achieves mutual conversion between rotational motion and reciprocating linear motion while reducing manufacturing cost and space saving with a compact configuration, improving life and high reliability. In addition, an object is to provide a crank mechanism with good maintainability, and a compressor or a pump using the crank mechanism.

  According to a first aspect of the present invention, there is provided a crankshaft, a crank web provided at least on one end side of the crankshaft and capable of rotating integrally with the crankshaft, and installed on the crank web, around the crankshaft. A crank mechanism comprising a crankpin that revolves, a crosshead formed with a slotted slot into which the crankpin is fitted, and a frame that guides the crosshead so that it can reciprocate linearly. The revolving motion of the crank pin and the reciprocating linear motion of the cross head are converted to each other through the groove.

In this way, by attaching a crankpin to a crank web that rotates integrally with the crankshaft, by fitting the crankpin into a slot in a long hole formed in the crosshead and revolving around the crankshaft, The crosshead can be directly reciprocated linearly, and conversely, the reciprocating linear motion of the crosshead can be converted into the rotational motion of the crankshaft.
With this configuration, the crank mechanism according to the present invention eliminates the connecting rod. Therefore, by eliminating the connecting rod with high processing difficulty, the production cost can be reduced,
Space-saving can be achieved and the installation area can be reduced by downsizing the rotation direction of the crankshaft. Also, by reducing the weight of the eccentric rotating part, it is possible to reduce or eliminate the balance weight, and to prevent the rocking movement of the cross head due to the rocking movement of the connecting rod. Therefore, wear of each sliding surface can be reduced, the burden on each member can be reduced, damage to the member can be prevented, life can be improved, and reliability can be increased.
Further, by eliminating the connecting rod, it is possible to eliminate the adverse effects due to precession, and to convert the reciprocating speed of the crosshead relative to the rotation angle of the crankshaft into a sine curve.

  The invention according to claim 2 is the crank mechanism according to claim 1, wherein a crankpin roller is rotatably mounted on the crankpin, and a slot of a long hole formed in the crosshead is provided. The width corresponding to the diameter of the crankpin roller is formed to have a length capable of reciprocating sliding by performing the revolving motion while rolling while the crankpin roller is fitted. Features.

  In this way, a crankpin roller was attached to the crankpin, and it was configured to slide and slide with the side surface of the slot of the long hole formed in the crosshead so that the crosshead reciprocates linearly. Therefore, the frictional resistance of the sliding surface can be reduced, wear can be reduced, and smooth operation can be ensured.

  A third aspect of the present invention is the crank mechanism according to the first or second aspect, wherein the crosshead is formed of a rectangular flat plate, and the frame includes the crosshead via a guide roller. The guide roller is slidably guided in the direction of the reciprocating linear motion, and the guide roller is attached to the cross head or the frame so as to guide the upper and lower end surfaces or the left and right side surfaces of the cross head in the reciprocating direction. It is characterized by being installed.

In this way, the cross head is formed of a rectangular flat plate, so that the accuracy control is easier and the manufacturing cost can be reduced and the maintenance can be reduced compared to the conventional arc head (see FIGS. 7 and 8). Also excellent in properties.
In addition, since the guide roller is provided and the sliding surface between the frame and the cross head is guided by rolling, the sliding resistance can be reduced, and damage such as wear and seizure of the sliding surface can be prevented. .

The invention according to claim 4 is the crank mechanism according to claim 3, wherein the frame that slides with the guide roller that guides the vertical direction of the crosshead or the sliding surface of the crosshead is reinforced. A member is provided.
Here, in this specification, the “reinforcing member” refers to a member whose strength and hardness are improved. In addition to a member whose surface hardness is increased by heat treatment or the like, a surface treatment such as a sheet-like liner or thermal spraying is used. Members are also included.

  Thus, by providing a reinforcing member on the sliding surface of the frame or the cross head that slides with the guide roller, the toughness as a structural member is ensured while improving the surface strength of the sliding surface. Can do. Therefore, damage to the sliding surface due to rolling of the guide roller can be prevented without impairing the rigidity of the frame and the cross head, and maintenance and life are improved.

  The invention according to claim 5 is the crank mechanism according to claims 1 to 4, wherein the cross head includes a reinforcing member that reinforces a side surface of the slot of the elongated hole. .

  As described above, the cross head includes a reinforcing member that reinforces the sliding surface between the crank pin and the crank pin roller formed on the end surface of the elongated hole, thereby improving load resistance, wear resistance, and the like. The sliding surface that is required can be made of a high-strength material, and the lifetime of the sliding surface is improved and the maintainability is improved while reducing the cost.

  A sixth aspect of the present invention is a compressor or pump having the crank mechanism according to any one of the first to fifth aspects, wherein the cross head is coupled in a direction in which the crosshead linearly moves. The piston rod, the piston connected to the piston rod, and the piston are reciprocally accommodated, and pressure chambers are formed in front and rear in the sliding direction of the piston, respectively, and communicate with the pressure chamber from the outside. And a cylinder in which a communication hole is formed.

  Thus, by using the crank mechanism according to any one of claims 1 to 5 for a compressor or a pump, the life is improved, the compression is highly reliable, and the maintenance is good. A machine or pump can be provided.

  The invention according to claim 7 is the compressor or pump according to claim 5, wherein the piston rod connected to the cross head is connected to both sides with respect to the direction of the reciprocating linear motion of the cross head. And the pistons are connected to the pinton rods, respectively.

As described above, the crank mechanism according to the present invention eliminates the connecting rod, so that the piston rod can be connected to both ends of the crosshead. Therefore, the compact structure improves the life, increases the reliability, and also performs maintenance. A highly horizontally opposed compressor or pump can be provided.
In addition, according to the present invention, a horizontally opposed compressor or pump can be configured in the plane of the reciprocating linear motion of the crosshead, so that the crank is compared with the conventional configuration in which two cranks are connected in the direction of the crankshaft. Space can be saved also in the direction of the shaft.

  According to the present invention, the compact configuration achieves mutual conversion between rotational motion and reciprocating linear motion while reducing manufacturing cost and space saving, improving life and increasing reliability. In addition, it is possible to provide a crank mechanism with good maintainability and a compressor or pump using the crank mechanism.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, the best mode for carrying out the invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing a configuration of a crank mechanism according to the present embodiment, FIG. 2 is a front view of the crank mechanism according to the present embodiment, and FIG. 3 is a sectional view taken along line XX in FIG.
Here, for convenience of explanation, the vertical direction and the front-rear direction of the crank mechanism are determined. In FIG. 3, the vertical direction on the figure is the vertical direction of the crank mechanism, the left side is the front on the figure, and the right side is the right side. Is after. The same applies to the case where the present crank mechanism is used for a compressor or a pump, which will be described later, and this direction may be applied to each component.

  As shown in FIGS. 1 to 3, the crank mechanism 1 according to this embodiment includes a rotating crankshaft 2, a crank web 3 that rotates integrally with the crankshaft 2, and an eccentricity to the crank web 3. The crankpin 4 installed in a rotatable manner, a crankpin roller 5 rotatably mounted on the crankpin 4, a reciprocating linear motion (reciprocating motion in the direction A shown in FIG. 2), and the crosshead 6. And a guide roller 11 and 12 for guiding the cross head 6 so as to freely reciprocate linearly.

  As shown in FIGS. 1 and 3, the crankshaft 2 is configured as a stepped round bar having a lock nut 2a on one end side. A crank web 3 to be described later is fixed to the end portion on the one end side with a lock nut 2a so as to be integrally rotatable via a key 2b. On the other hand, a key groove 2c in which a V pulley for driving the crankshaft 2 is mounted is formed at the other end. The crankshaft 2 is rotatably supported on the outer peripheral surface 2d (see FIG. 3) of the crankshaft 2 via a tapered roller bearing 21.

The crank web 3 is formed in a thick ring shape, and a step portion 3a to which the lock nut 2a of the crankshaft 2 is attached is formed on the end surface on the front end side (see FIG. 3). Further, a key groove 3b is formed on the inner peripheral surface, and the crankshaft 2 and the crank web 3 are fixed through a key 2b attached to the key groove 3b (see FIG. 1).
The crank web 3 is formed with a hole 3c through which the crank pin 4 is inserted at a position offset from the rotation center of the crankshaft 2 by a predetermined amount. The hole 3c is provided with a counterbore hole to which the nut 4a is attached. It has been.
The crank web 3 according to the present embodiment corresponds to a conventional crank arm. However, in terms of countermeasures for unbalance of the rotating portion, the rotor is not statically unbalanced but based on the idea of “unbalanced”. Vibration is reduced in consideration of the ratio of the unbalance amount to the total weight. As a result, the balance weight is eliminated and the danger of the balance weight falling off is completely avoided.

  A crankpin roller 5 is rotatably fixed to the distal end side (crosshead 6 side) of the crankpin 4 and a male screw to which the nut 4a is screwed is formed on the other end side. The crankpin roller 5 uses a needle bearing in order to ensure smooth rotation while reducing the weight from the unbalanced idea.

As shown in FIGS. 1 and 2, the crosshead 6 is formed of a rectangular flat plate. In the present embodiment, the vertical direction of the cross head 6 is guided by the guide rollers 11 disposed on the upper and lower end faces of the cross head 6, and the horizontal direction with respect to the reciprocating motion direction is determined from the upper and lower frames 9 b and 9 c to the left and right of the cross head 6. The guide roller 12 is arranged so as to be in contact with the side surface thereof, and is guided so as to reciprocate linearly. The guide rollers 11 and 12 use needle bearings in order to ensure smooth rotation and consider maintainability.
A clearance hole 6a is formed at the center of the cross head 6 so as not to interfere when the crankpin roller 5 slides back and forth (see FIG. 1).
Further, a step portion 6b on which a later-described reinforcing member 8 is installed is formed on the peripheral portion of the escape hole 6a (see FIG. 1), and this step portion 6b corresponds to the position of the mounting bolt 8b of the reinforcing member 8. And the internal thread 6c is formed in the four corners.

The reinforcing member 8 installed in the cross head is formed of a rectangular flat plate, and a central slot is provided with a slotted through hole for guiding the revolving motion of the crankpin roller 5 and converting it into a reciprocating linear motion. 8a is formed.
Therefore, the width of the slot 8a of the long hole corresponds to the diameter of the crankpin roller 5, and the crankpin roller 5 can be configured to have an appropriate clearance so that it can roll along the side surface of the slot 8a of the long hole. Is set. Further, the length of the slot 8a of the elongated hole is determined in accordance with the length of reciprocation as the crankpin roller 5 revolves.
In addition, although the slot 8a of the long hole formed in the reinforcement member 8 is set as the structure arrange | positioned along the direction orthogonal to the reciprocating motion direction of the crosshead 6, it is not limited to this, A crossing It suffices if it is arranged in the direction to be.
Further, since the side surface of the slot 8a of the elongated hole rolls by line contact with the crankpin roller 5, it is necessary to improve the sliding characteristics of this portion. In this embodiment, the reinforcing member 8 is quenched. Processing has been applied. As a result, the crankpin roller 5 is reduced in size and reduced in weight.

As shown in FIG. 3, the frame 9 is configured as a housing that guides and accommodates the crosshead 6 so as to be capable of reciprocating linear movement, and includes a frame body 9a, an upper frame 9b, a lower frame 9c, and a bearing housing 9d. It is configured with.
The frame body 9a is a frame 9a _1, 9a ₂ before and after, the welding structure composed of the rib 9a ₃ Metropolitan coupling the frame 9a _1, 9a ₂ in the front and rear.
The upper and lower frames 9b and 9c are formed of flat plates and are fixed to the frame body 9a so as to cover the upper and lower surfaces of the frame body 9a. Further, a reinforcing member 10 that forms a sliding surface with the outer peripheral surface of the guide roller 11 rotatably installed on the cross head 6 is provided on the upper and lower frames 9b and 9c along the reciprocating direction of the cross head 6. Installed. In the present embodiment, the reinforcing member 10 is a member that has been subjected to a quenching process.
Further, guide rollers 12 for guiding the left and right side surfaces of the cross head 6 with respect to the reciprocating direction of the cross head 6 are provided on the upper and lower frames 9b and 9c. It is installed in the predetermined position which contacts each side surface (refer also to FIG. 1). In addition, a needle bearing is used for the guide roller 12 to ensure smooth rotation, thereby guiding the cross head 6 in the left-right direction with respect to the reciprocating direction.
The bearing housing 9d is fixed to the side plate 9a ₂ of the frame body 9a, through the tapered roller bearings 21, rotatably holds the crankshaft 2, and has a structure which can burden the thrust load.

Next, the operation of the crank mechanism according to the present embodiment will be described with reference to FIGS. 1 to 3. Here, the operation when the rotation of the crankshaft 2 by the crank mechanism 1 is converted into the reciprocating linear motion of the crosshead 6 will be described. Conversely, the reciprocating linear motion of the crosshead 6 is changed to the rotational motion of the crankshaft 2. The same applies to the case of conversion.
A V pulley is coupled to the crankshaft 2 with a key (not shown), and the crankshaft 2 can be rotated by rotating the V pulley with a motor (not shown) via a V belt (not shown). This rotational movement of the crankshaft 2 is transmitted to a crank web 3 that is integrally connected by a key 2b. The crank web 3 is provided with a crank pin 4 at a position eccentric from the center of rotation of the crank shaft 2 by a predetermined amount, and a crank pin roller 5 is rotatably mounted on the crank pin 4. The crankpin roller 5 revolves around the crankshaft 2.
In the present embodiment, as an example, the crankshaft 2 is rotated via a V pulley, but the present invention is not limited to this, and a gear or the like may be used, and the crankshaft 2 is rotated. The present invention can be implemented regardless of the means.

On the other hand, the crosshead 6 is slidably guided by the frame 9 via the guide rollers 11 and 12 in the direction in which the reciprocating linear motion is performed. The cross head 6 has a width corresponding to the diameter of the crank pin roller 5 via a reinforcing member 8 in a direction perpendicular to the direction in which the cross head 6 reciprocates linearly, and the crank pin roller By performing the revolving motion in a state in which 5 is fitted, a slot 8a having a long hole length capable of reciprocating sliding is formed.
Further, the cross head 6 faces the crank web 3 so that the crank pin roller 5 is fitted in a slot 8a having a long hole formed in the reinforcing member 8 disposed on the cross head 6. Has been placed.

Therefore, the slot 8a formed in the cross head 6 through the reinforcing member 8 is formed in a direction orthogonal to the direction of the reciprocating linear motion of the cross head 6, so that the cross head 6 In the direction of linear motion, the crank pin 4 moves constrained by the moving direction. On the other hand, the crosshead 6 does not receive an external force because the slot 8a having the elongated hole is formed in a direction (direction B in FIG. 2) perpendicular to the direction of the reciprocating linear motion.
Therefore, the crosshead 6 reciprocates linearly in the direction of the reciprocating linear motion by the rotational motion of the crankshaft 2.

Then, the compressor using this crank mechanism is demonstrated. The same applies to the case where this crank mechanism is used for a pump, and the crank mechanism itself is the same, so that the description thereof is omitted.
The crank mechanism according to any one of claims 1 to 5 according to the present invention is not limited to a pump or a compressor, and is widely applied to an internal combustion engine, an external combustion engine, and the like. Is possible.

FIG. 4 is a plan view showing a configuration of a compressor using the crank mechanism.
As shown in FIG. 4, the compressor 30 according to the present embodiment includes a crank mechanism 1 according to the embodiment, a piston rod 31 connected to an end surface 6e of the crosshead according to the crank mechanism 1, and the piston rod. A piston 32 connected to the cylinder 31; a cylinder 33 which accommodates the piston 32 so as to be capable of reciprocating linear movement; first and second pressure chambers 34 and 35 formed inside the cylinder; 35 is provided with communication holes 36 and 37 communicating from the outside.
Since the other configuration is well known as the configuration of the compressor or pump, the description thereof is omitted.

The piston rod 31 is configured as a stepped round bar having male screws 31a and 31b formed at both ends. The end on one end side is inserted into the end face 6e of the crosshead and is fixed by a crosshead nut 38.
Since the piston 32 is mounted on the other end side of the piston rod 31, a male screw 31b is formed at the tip of the other end side.

  The piston 32 includes a piston body 32a and a piston cover 32b. The piston main body 32a is formed in a cylindrical shape with a bottom, and a piston cover 32b is fitted so as to cover the end face on the open side. The piston 32 is fixed to the piston rod 31 by screwing the piston nut 39 to the male screw 31 b on the other end side of the piston rod 31 in a state where the piston 32 is inserted into the other end side of the piston rod 31.

The cylinder 33 includes a cylindrical cylinder body 33a that accommodates the piston 32 in a reciprocating manner, a front head 33b, and a rear head 33c. A seal ring 42 and a packing 43 are mounted on the inner peripheral surface of the cylinder body 33a to ensure confidentiality with the piston 32 and smooth sliding.
A front head 33b and a rear head 33c are fixed to the cylinder body 33a via gaskets (not shown), and pressure chambers 34 and 35 are formed in the cylinder body 33a so as to be sealed before and after the piston 32 in the reciprocating direction. The pressure chambers 34 and 35 are respectively formed with communication holes 36 and 37 that communicate with the outside of the cylinder 33.
Therefore, in FIG. 4, if the crosshead 6 moves to the right in the figure, the piston 32 also moves to the right, and air flows from the first communication hole 36 communicating with the first pressure chamber 34. While being introduced, air is discharged from the second communication hole 37 communicating with the second pressure chamber 35. In the present embodiment, the fluid introduced into and discharged from the pressure chambers 34 and 35 has been described as air. However, the present invention is not limited to this, and the present invention is not limited to oil, hydrogen gas, propane gas, and other various types. It can be applied to various fluids such as refrigerants.

Finally, a modification of the crank mechanism according to the present invention will be described.
FIG. 5 is a diagram showing a main configuration of a horizontally opposed compressor or pump using the crank mechanism. As shown in FIG. 5, piston rods 31 are connected to both sides of the crosshead 6 according to the crank mechanism 1, and a cylinder 33 and a piston 32 are respectively formed on the left and right in the figure, so that a horizontally opposed compressor or The pump is configured.

Furthermore, another modified example will be described.
FIG. 6 is a diagram for explaining another modification according to the present invention. In this modification, the cylinder-shaped crankpin 4 and the box-pin two divided by the crankpin roller 5 (see FIG. 1) according to the above-described embodiment are configured so as to embrace the crankpin 4. The slide member 51 and a bearing 41 mounted on the inner peripheral surface side of the slide member 51 are provided.
In the crank mechanism 1 ′ according to this modification, the slide member 51 reciprocally slides on the side surface of the slot 61 formed in the crosshead 6 in accordance with the revolving motion of the crankpin 4, thereby causing the crosshead 6 to move. The reciprocating movement provides the same effect as the crank mechanism 1 (see FIG. 1) according to the above embodiment.

The embodiment that seems to be the best of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and can be implemented with appropriate modifications within the scope of the same technical idea.
For example, in the present embodiment, the crank web is configured as a separate body from the crankshaft and employs a structure that is fitted to the crankshaft via a key, but is not limited thereto. You may comprise integrally.
Furthermore, it is also possible to configure the crankshaft in a cantilever manner and to dispose a crosshead on both sides of the crankshaft with a driven V pulley interposed therebetween.

  In addition, regarding the guide roller that guides the reciprocating slide of the cross head, the vertical guide roller is disposed on the cross head and the left and right guide is disposed on the upper and lower frames. Alternatively, both may be installed on the crosshead. Further, the guide roller is not necessarily installed, and the cross head and the frame may be slid instead of rolling. However, since the centrifugal force in the rotation direction of the crankshaft acts on the vertical guide portion of the crosshead, it is desirable to install a guide roller as in this embodiment.

It is a perspective view which shows the principal part of the structure of the crank mechanism which concerns on this embodiment. It is a front view which shows the principal part of the crank mechanism which concerns on this embodiment. It is XX sectional drawing in FIG. 1 for demonstrating the crank mechanism which concerns on this embodiment. It is a figure which shows the structure of the cylinder part connected with the crank mechanism which concerns on this embodiment. It is a schematic diagram which shows the horizontally opposed compressor etc. which utilized the crank mechanism which concerns on this embodiment. It is a figure which shows the modification of the crank mechanism which concerns on this embodiment. It is sectional drawing which shows the conventional crank mechanism. It is YY sectional drawing of FIG.

DESCRIPTION OF SYMBOLS 1 Crank mechanism 2 Crankshaft 2a Lock nut 2b Key 3 Crank web 4 Crankpin 5 Crankpin roller 6 Crosshead 6a Escape hole 6b Step part 8 Reinforcement member 8a Slotted groove 8b Mounting bolt 9 Frame 10 Reinforcement member 11 Guide roller 12 Guide roller 30 Compressor 31 Piston rod 32 Piston 33 Cylinder 34 First pressure chamber 35 Second pressure chamber 36 First communication hole 37 Second communication hole

Claims (7)

A crankshaft, a crank web provided on at least one end of the crankshaft and capable of rotating integrally with the crankshaft, a crankpin installed on the crankweb and revolving around the crankshaft, and the crankshaft A crosshead in which a slot with a long hole for fitting a pin is formed, and a frame for guiding the crosshead so as to freely reciprocate linearly;
A crank mechanism characterized in that the revolving motion of the crank pin and the reciprocating linear motion of the crosshead are mutually converted through the slot of the elongated hole.   A crankpin roller is rotatably mounted on the crankpin, and a slot in the elongated hole formed in the cross head has a width corresponding to the diameter of the crankpin roller, and the crankpin roller 2. The crank mechanism according to claim 1, wherein the crank mechanism is formed to have a reciprocating sliding length by performing the revolving motion while rolling in a fitted state. The crosshead is composed of a rectangular flat plate,
The frame guides the cross head slidably in the direction of the reciprocating linear motion via a guide roller,
The said guide roller is installed in the said cross head or the said frame so that the up-and-down end surface or right and left side surface of the said cross head may be guided to the said reciprocation direction. The crank mechanism described in 1.   The crank mechanism according to claim 3, wherein a reinforcing member is provided on the frame that slides with the guide roller that guides the vertical direction of the crosshead or the sliding surface of the crosshead.   The crank mechanism according to any one of claims 1 to 4, wherein the cross head includes a reinforcing member that reinforces a side surface of the slot of the elongated hole. It has a crank mechanism given in any 1 paragraph among Claims 1-5,
Furthermore, a piston rod connected in a direction in which the crosshead reciprocates linearly;
A piston connected to the piston rod;
A cylinder in which the piston is reciprocally moved and a pressure chamber is formed in front and back in the sliding direction of the piston, and a communication hole is formed in the pressure chamber.
A compressor or pump comprising:   7. The piston rod connected to the cross head is connected to both sides with respect to the direction of reciprocating linear motion of the cross head, and the piston is connected to the piston rod, respectively. A compressor or pump as described in.

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