JP6607776B2 - Reciprocating compressor - Google Patents

Description

  The present invention relates to a reciprocating compressor.

  There exists patent document 1 as background art of this invention. In Patent Document 1, the inside of a cylinder 17 is formed by a disk part 25 provided on the distal end side of a connecting rod 24 and a retainer 28 attached to the disk part 25 and having an outer diameter equal to or smaller than the outer diameter of the disk part 25. The piston 31 that reciprocates while swinging, and the inner circumferential side becomes an annular clamping part 42 that is sandwiched between the disk part 25 and the retainer 28 of the piston 31, and the outer peripheral side faces outward from the clamping part 42 and is on the retainer 28 side. The reciprocating compressor is provided with a lip seal 41 that protrudes to the inner peripheral surface of the cylinder 31 and forms an annular lip portion 43.

JP 2009-243342 A

  In the lip ring (lip seal 41) of the reciprocating compressor in Patent Document 1, at least the diameter in the middle direction between the drive shaft direction and the swing direction is not shorter than the diameter in the swing direction and the drive shaft direction. For this reason, the pressing force generated when the lip ring is assembled with the cylinder core shifted and the inertial force due to the swing act as stress, and uneven wear occurs in the intermediate direction between the drive shaft direction and the swing direction. The life of the ring could not be improved.

  In view of the above, an object of the present invention is to provide a reciprocating compressor that reduces uneven wear of a lip ring and improves the replacement life of the lip ring.

  In order to solve the above problems, for example, the configuration described in the claims is adopted.

  The present invention includes a number of means for solving the above-mentioned problems. For example, a cylinder, a cylinder head provided at an end of the cylinder, and a reciprocating motion while swinging in the cylinder. And a drive shaft that drives the piston, and a lip ring that seals a gap between the cylinder and the piston, and the length from one end to the other end of the lip ring in the swinging direction and the drive shaft The length from one end to the other end in the intermediate direction between the swing direction and the drive shaft direction as viewed from the cylinder head side is shorter than the length from one end to the other end in the direction. A reciprocating compressor is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the reciprocating compressor which reduced the partial wear of the lip ring and improved the exchange lifetime of the lip ring can be provided.

It is an example of the structure of the reciprocating type air compressor in this invention. FIG. 2 is a side sectional view of a main body portion of the reciprocating air compressor in FIG. 1. It is an example of a structure of the piston in this invention. It is an example of the mode of a deformation | transformation of a cylinder at the time of cylinder head assembly | attachment. It is a lip ring shape in Example 1 of this invention. This is the pressing force to the cylinder of the lip ring during swinging. It is a lip ring shape in Example 2 of the present invention. It is a lip ring shape in Example 3 of the present invention. It is an example of the contact to the cylinder of a lip ring at the time of lip ring rocking | fluctuation. It is an example of the contact to the cylinder of a lip ring at the time of lip ring rocking | fluctuation. It is sectional drawing of a lip ring angle | corner R part. It is a lip ring shape in Example 5 of this invention.

  Embodiment 1 of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an outline of a reciprocating compressor according to the present invention, and FIG. 2 shows a sectional view of the reciprocating compressor main body in FIG. In this embodiment, an air compressor that compresses air will be described as an example, but not limited to air, a specific gas such as nitrogen or oxygen may be compressed. Further, a booster compressor that boosts the pressure may be used. As shown in FIG. 1, the reciprocating compressor is composed of an air tank 1, an electric motor 2 mounted on the air tank 1, and a compressor body 3, and the motive power of the electric motor 2 is compressed through a transmission belt 4 and compressed. It is transmitted to the machine body 3. As shown in FIG. 2, the internal structure of the compressor body 3 includes a crank chamber 21, a cylinder 22 projecting vertically from the crank chamber 21, and an air valve provided in the cylinder 22 that opens and closes by reciprocating movement of the piston. 23, a cylinder head 24 provided at the end of the cylinder 22 opposite to the crank chamber 21, a crankshaft 26 as a drive shaft rotatably supported at the center of the crank chamber 21, and a crankshaft 26. It has a piston to be driven. The piston driven by the crankshaft 26 reciprocates in the cylinder 22 from the crank chamber 21 side to the cylinder head 24 side to compress the fluid in the compression chamber 27. The piston is constituted by a connecting rod 25 attached to the crankshaft 26 and a retainer 32 provided at the end of the connecting rod 25. The crankshaft 26 is rotated by the power transmitted through the transmission belt 4 from the electric motor 2 in which the piston portion 25 a that compresses the fluid is constituted by the retainer 32 and the end of the connecting rod 25, so that it is installed in the cylinder 22. The piston portion 25a of the piston thus moved reciprocates in the vertical direction while swinging. As a result, air is sucked from the outside of the cylinder 22 through the air valve 23, compressed and discharged.

  In this embodiment, the drive shaft is the crankshaft 26 and the connecting portion of the crankshaft 26 with the connecting rod 25 is decentered to convert the rotational motion of the drive shaft into the swinging motion of the connecting rod 25. . Not limited to this, the drive shaft itself does not have an eccentric portion, and the rotational motion of the drive shaft may be converted into the eccentric motion of the connecting rod 25 by connecting the drive shaft to a position eccentric from the center of the eccentric member. .

  1 and 2, for the sake of simplification of description, the shape of the air compressor is a single cylinder having only a pair of cylinders 22 and connecting rods 25, but a plurality of cylinders 22 Some air compressors have a connecting rod 25.

  FIG. 3 shows a sectional view of the piston portion 25a of the piston. An annular lip ring 31 that seals between the cylinder 22 and the piston portion 25a of the piston is sandwiched between the connecting rod 25 and the retainer 32, and the piston portion 25a of the piston reciprocates as the crankshaft 26 rotates. Compress. In the compression process of moving the compression chamber 27 from the bottom dead center where the compression chamber 27 is most expanded to the top dead center where the compression chamber 27 is most contracted, the side surface 31a of the lip ring 31 is pressed against the inner peripheral surface of the cylinder 22 by the cylinder internal pressure. The pressure causes the lip ring 31 to expand radially outward, and seals between the cylinder 22 and the piston portion 25a of the connecting rod. Therefore, the sealing performance of the lip ring 31 improves as the pressing force of the lip ring 31 against the cylinder 22 increases. On the other hand, since the amount of wear on the side surface of the lip ring 31 is proportional to the pressing force, in order to prevent the lip ring 31 from being worn, it is necessary to reduce the pressing force while maintaining a certain degree of sealing performance.

  The cylinder head 24 is fastened to the cylinder 22 using fastening bolts 41. At this time, by tightening the cylinder 22 with the fastening bolt 41, the cross section 22a of the cylinder 22 undergoes quaternary deformation in which four crests and four troughs are continuously connected like the cylinder cross section 22b of FIG. In the xy 45 degree direction, which is an intermediate direction between the crankshaft direction and the swinging direction, the cylinder 22 is deformed so that its diameter is reduced, so that the tightening margin of the lip ring 31 is increased and the pressing force is increased.

  A method for reducing the pressing force of the lip ring 31 will be described. In the compression process described above, the pressing force 51 due to the inertia of the connecting rod 25, the pressing force 52 due to the misalignment of the lip ring 31 with the cylinder 22, the internal pressure of the cylinder 22 and the tightening of the lip ring 31 are applied to the lip ring side surface 31a. The pressing force 53 due to the bill works.

  Here, when the lip ring 31 is formed in a circular shape, the pressing force 52 due to misalignment is greatest in the drive shaft direction orthogonal to the swing direction, and the inertial force due to swing is greatest in the swing direction. The sum of these stresses is greatest in the intermediate direction between the drive shaft direction and the swing direction.

  FIG. 5A shows the shape of a conventional lip ring 31. In the top view of the cylinder 22 and the lip ring 31, the crankshaft direction is the x direction and the swing direction is the y direction. In the x direction, the pressing force 51 due to the inertial force of the connecting rod 25 does not work out of the aforementioned pressing forces. However, in the xy 45 degree direction (the intermediate direction between the x direction and the y direction), the increase / decrease in the gap between the lip ring 31 and the cylinder 22 due to the swing is small, and the pressing force 51 due to the inertial force of the connecting rod 25 also acts. In the direction (intermediate direction between the x direction and the y direction), the total pressing force 54 is maximized, and the lip ring 31 is unevenly worn in the xy 45 degree direction 55.

  Here, there is a method of increasing the thickness of the bottom surface of the lip ring 31 as a measure for reducing the stress generated in the lip ring 31. However, the diameter of the lip ring 31 does not increase because the lip ring 31 is tilted by the swing, but the diameter projected from the lip ring 31 in the direction perpendicular to the axis of the cylinder 22 is the swing angle and the thickness of the bottom surface of the lip ring 31. Increase or decrease in proportion to the height. Therefore, as the thickness of the bottom surface of the lip ring 31 increases, the tightening allowance of the lip ring 31 increases and the pressing force in the swinging direction increases. That is, simply increasing the thickness of the bottom surface of the lip ring 31 is not a measure for reducing the stress generated in the lip ring 31, and uneven wear cannot be reduced.

  Therefore, in the lip ring shape of this embodiment shown in FIG. 5B, the outer diameter (length from one end to the other end) D1 of the W portion, which is the xy 45 degree direction, of the lip ring 31 is set in the x direction and the y direction. By reducing the outer diameter (length from one end to the other end) at D0, the pressing force 52, 53 due to misalignment and tightening margin in the xy45 degree direction of the lip ring 31 was relaxed.

  FIG. 6 shows the pressing force 54 to the cylinder 22 of the lip ring 31 in the FEM analysis. In the conventional lip ring shape 31 shown in FIG. 6A, the lip ring 31 is strongly pressed against the cylinder 22, particularly in the direction of xy 45 degrees, by the pressing forces 52 and 53 due to the tightening allowance and misalignment. On the other hand, in the shape of the lip ring 31 of this embodiment shown in FIG. 6B, a sufficient gap in the xy 45 degree direction between the cylinder 22 and the lip ring 31 is secured, and the pressing force 54 (center misalignment and tightening) of the lip ring 31 is secured. By reducing the pressing force 52, 53) due to the margin, the pressing force of the lip ring 31 in the xy 45 degree direction can be reduced.

  According to the present embodiment, by reducing the pressing force applied in the intermediate direction between the swing direction of the lip ring 31 and the drive shaft direction, uneven wear can be reduced and the replacement life of the lip ring 31 can be improved.

  A reciprocating compressor according to a second embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The shape of the lip ring 31 shown in the first embodiment can relieve the pressing force acting on the lip ring 31 and suppress wear, but on the other hand, the recess 22b provided on the outer diameter of the lip ring 31 allows the cylinder 22 A gap is generated between the lip ring 31 and the sealing performance of the lip ring 31 is lowered, resulting in a decrease in discharge performance.

  In this embodiment, the side surface 31a of the lip ring 31 is formed by using an ellipse 71 having a major axis in the crankshaft direction and an ellipse 72 having a major axis in the swinging direction. Of the pressing force acting on the side surface 31a of the lip ring, the pressing force due to the inertial force of the connecting rod 25 increases in proportion to the absolute value of the angle θ from the crankshaft direction to the swinging direction. Decreases in proportion to the absolute value of θ.

  Therefore, by reducing the pressing force applied to the lip ring 31 by reducing the gap between the cylinder 22 and the lip ring 31 by reducing the sealing force by reducing the pressing force applied to the lip ring 31 by reducing the sealing performance. Can be relaxed.

  In addition, the joint part of the ellipse 71 long in the crankshaft direction and the ellipse 72 long in the swinging direction may be smoothly connected.

  Further, like the lip ring 31 shown in FIG. 8, the shape of the lip ring 31 is combined with an arc extending radially outward and an arc extending radially inward in accordance with the deformation of the cylinder 22 when the cylinder head 24 is fastened. Shape. The shape spreads radially outward in the swing direction and crankshaft direction, and has a shape spreading radially inward in the intermediate direction. Thereby, the pressing force accompanying the increase in the tightening margin in the xy 45 degree direction when the cylinder head 24 is fastened can be more effectively reduced.

  As described above, according to the present embodiment, it is possible to reduce the uneven wear and improve the replacement life of the lip ring 31 while alleviating the reduction in the sealing performance of the lip ring 31 as compared with the first embodiment.

  A reciprocating compressor according to Example 3 of the present invention will be described with reference to FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. In the present embodiment, a structure capable of reducing the pressing force by changing the tightening allowance of the lip ring 31 accompanying the swing will be described.

  The projected length D2 of the lip ring outer diameter in the direction perpendicular to the cylinder axis when the lip ring 31 shown in FIG. 9 swings is calculated using the bottom surface thickness t, the lip ring outer diameter D0, and the swing angle β (1) ).

  However, when the tip end side of the side surface 31b in the rocking direction of the lip ring is in contact with the cylinder 22 when the lip ring 31 is expanded radially outward, the side surfaces excluding the bottom surface of the lip ring are as shown in FIG. The cylinder 22 is pressed against and deforms. Therefore, the maximum value D2max of the outer diameter at the time of oscillation is determined by the equation (2) using the bottom surface thickness t and the lip ring outer diameter D0, and the maximum increase amount of the tightening allowance during the compressor operation by the equation (3). ΔD is determined.

  In proportion to the increase in the interference, the pressing force due to the interference increases. In order to reduce the increase in the tightening allowance due to the swing, it is conceivable to reduce the bottom surface thickness. However, if the bottom surface thickness is reduced, the strength is lowered and the replacement life of the lip ring 31 cannot be improved. Therefore, by increasing the radius of curvature R of the outer corner portion of the lip ring shown in FIG. 9, ΔD is reduced and the pressing force due to the increase in the tightening margin is reduced. The maximum projected length D3max of the outer diameter of the lip ring in the direction perpendicular to the cylinder axis when the radius of curvature in the swinging direction is R1 is expressed by equation (4), and when the radius of curvature is 0 according to equation (5). From equation (3), it can be seen that the interference is reduced by ΔD2, and the larger the radius of curvature R is, the more the pressing force can be relaxed.

  On the other hand, in the swinging direction, a pressing force due to the inertial force of the connecting rod 25 acts on the lip ring side surface 31b, so that the lip ring outer corner (the outer peripheral surface of the bent portion between the side surface 31 and the bottom surface of the lip ring 31). When the radius of curvature R is increased, the surface pressure acting on the oscillating direction lip ring side surface 31b increases, and wear due to inertial force increases.

  In view of the above, in this embodiment, as shown in FIG. 11, when the radius of curvature in the swinging direction is R1 and the radius of curvature in the intermediate direction is R2, R2> R1 so that the tightening margin is increased. The pressing force due to can be reduced.

  A reciprocating compressor according to Example 4 of the present invention will be described with reference to FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  The lip ring 31 described in the first, second, and third embodiments has an assembly direction. Therefore, a concave portion is provided at a position that is not point-symmetric, such as a small hole 31c or a notch 31D, in the holding portion that is fixed to the lip ring 31 by the piston 25a and the retainer 32. Further, by providing the retainer 32 with a convex portion that corresponds to the concave shape provided on the lip ring 31 and can be fitted into the concave shape, it is possible to prevent the lip ring 31 from being displaced when assembled. Further, it also functions to prevent the lip ring 31 from being rotated after assembly.

  According to the present embodiment, it is possible to prevent the lip ring 31 from being displaced when assembled, to reduce the pressing force due to the misalignment, and to reduce the uneven wear of the lip ring 31.

  The embodiments described so far are merely examples for carrying out the present invention, and the present invention may be implemented by combining the embodiments 1-4.

DESCRIPTION OF SYMBOLS 1 Air tank 2 Electric motor 3 Compressor body 4 Electric belt 21 Crank chamber 22 Cylinder 22a Cylinder step surface 22b Cylinder cross section 23 after cylinder head tightening Air valve 24 Cylinder head 25 Connecting rod 26 Crankshaft 27 Compression chamber 31 Lip ring 31a Lip ring Side surface 31b Lip ring side surface (swing direction)
32 Retainer 41 Fastening bolt 51 Pushing force due to swinging inertia force 52 Pushing force due to cylinder misalignment 53 Lip ring diameter expansion due to cylinder internal pressure and pushing force due to tightening allowance 54 Total pushing force 55 Uneven wear location 71 Lip in Example 2 Ring theoretical curve 72 Lip ring theoretical curve in Example 2

Claims (10)

A cylinder,
A cylinder head provided at an end of the cylinder;
A piston that reciprocates while swinging in the cylinder;
A drive shaft for driving the piston;
A lip ring that seals a gap between the cylinder and the piston;
The length of the lip ring from one end to the other end in the swing direction and the length from one end to the other end in the drive shaft direction are intermediate between the swing direction and the drive shaft direction when viewed from the cylinder head side. The reciprocating compressor characterized by shortening the length from one end to the other end in the intermediate direction.   The reciprocating compressor according to claim 1, wherein the lip ring has a shape in which an ellipse having a major axis in the swinging direction and an ellipse having a major axis in the drive shaft direction are connected. According to claim 1, characterized in that in the swinging direction and the driving direction of the rippling a shape of a combination of a circular arc extending inner side arc extending outer side in the intermediate direction of the rippling Reciprocating compressor. 2. The curvature radius R <b> 1 in the swing direction and the drive shaft direction is made smaller than the curvature radius R <b> 2 in the intermediate direction at a bent portion between the side surface and the bottom surface of the lip ring. Reciprocating compressor. The lip ring has a hole or notch;
The reciprocating compressor according to claim 1, wherein the piston has a convex portion fitted into the hole or the notch. A cylinder,
A piston that reciprocates while swinging in the cylinder;
An electric motor for driving the piston;
A drive shaft that rotates by the power of the electric motor and reciprocates the piston;
It said piston includes a lip ring which is sandwiched between a retainer attached to the end of the connecting rod and connecting rod attached to the front SL drive shaft, and the connecting rod and the retainer,
The length from one end to the other end in the swing direction of the lip ring and the length from one end to the other end in the drive shaft direction are different from one end to the other in the intermediate direction between the swing direction and the drive shaft direction. A reciprocating compressor characterized in that the length to the end is short. The reciprocating compressor according to claim 6, wherein the lip ring has a shape in which an ellipse having a major axis in the swinging direction and an ellipse having a major axis in the drive shaft direction are connected. Claim 6, characterized in that in the swinging direction and the driving direction of the rippling a shape of a combination of a circular arc extending inner side arc extending outer side in the intermediate direction of the rippling Reciprocating compressor. 7. The curvature radius R <b> 1 in the swing direction and the drive shaft direction is set to be smaller than the curvature radius R <b> 2 in the intermediate direction at a bent portion between a side surface and a bottom surface of the lip ring. Reciprocating compressor. The lip ring has a hole or notch;
The reciprocating compressor according to claim 6, wherein the retainer or the connecting rod has a convex portion that fits into the hole or the notch.

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