JP2021110274A - Compressor, piston, and connecting rod - Google Patents

Abstract

To provide a compressor, a piston and a connecting rod, which have a structure in which a rocking piston made of resin is fixed by screwing, and can suppress loosening of screws due to creep deformation of the resin.SOLUTION: In a compressor 10, a piston 33 is a rocking type that reciprocates in a cylinder 22 while rocking with rotation of a crankshaft 24, in which at least an outer peripheral surface 33a contacting an inner peripheral side of the cylinder 22 and an upper surface 33c on a valve plate 26 side are made of a wear-resistant resin. The piston has female screw holes 41c opened to a crankcase 21 side on an end side that is fixed to a connecting rod 32 side, and the outer peripheral surface 33a is a spherical surface having a diameter smaller than the diameter of the cylinder 22.SELECTED DRAWING: Figure 3B

Description

The present invention relates to compressors, pistons, and connecting rods.

As an example of a multi-stage compressor that can handle high pressure, Patent Document 1 describes a multi-stage compressor in which a low-pressure compressor and a high-pressure compressor are connected, and swings in the cylinder of the low-pressure compressor. A locking piston that is movable and slidable, and a locking piston that is swingable and slidable in the cylinder of the high-pressure compressor are provided, and the locking piston of the high-pressure compressor swings. It is stated that the angle was made smaller than the swing angle of the locking piston of the low pressure compressor.

Japanese Unexamined Patent Publication No. 2015-132267

Conventionally, in a reciprocating compressor that compresses a fluid, a normal piston system in which a bearing is provided at the end of the connecting rod on the compression chamber side and the piston is supported by the bearing so as to swing, and the connecting rod are compressed. There is a swing piston system in which a piston that does not have a bearing on the chamber side and is integrated with a connecting rod has a seal ring that elastically deforms to seal the compressed fluid.

Compared to the normal piston method, the latter swing piston method has a simpler structure because it does not have bearings or piston pins, there are no design restrictions due to the bearing temperature, and the reciprocating mass can be reduced. It has many merits such as.

In such a swinging piston, as described in Patent Document 1, a structure in which the piston is screwed to the connecting rod from the seat surface side may be adopted.

However, in this screwed structure, since the metal part is exposed on the upper surface of the piston which is the seating surface, there is a problem that the heat of compression is transferred to the connecting rod side via the part. If the heat of compression is transferred to the connecting rod side, there is a concern that the lubrication state of the large end bearing may deteriorate, so different measures are required.

On the other hand, as a result of diligent studies by the present inventors, in the swing piston method, the piston is made of a resin having excellent wear resistance or the like, and the outer peripheral surface of the piston is a spherical surface having a diameter smaller than the diameter of the cylinder. I came up with the idea.

According to this structure, even in a reciprocating compressor having a long piston stroke and a large tilt angle (swing angle) of the connecting rod, the gap between the outer peripheral surface of the piston and the inner wall surface of the cylinder is maintained to be minute, which makes it smooth. It was clarified that the effect of being slidable can be obtained.

However, even in such a structure, since the resin serving as the bearing surface directly receives the axial force accompanying the fastening of the screws, there is room for improving the loosening of the screws due to the creep deformation of the piston made of the resin. It has been clarified by the examination by the present inventors that there is a problem.

In particular, during compressor operation, the upper surface of the piston is exposed to a high temperature by the heat of compression, so that creep deformation progresses rapidly. Then, once the screw is loosened, the piston rattles due to the reciprocating inertial force and the frictional force with the cylinder, which may cause a problem that the screw breaks or the piston breaks in a chain.

This damage mode may eventually interfere with the operation of the compressor, such as breaking the connecting rod and breaking the crankcase, so countermeasures are indispensable.

As a part of such resin creep countermeasures, it is conceivable to select a resin material having excellent creep resistance. However, such resins are generally expensive. Since the piston, which is a sliding component in the above structure, needs to be replaced regularly due to wear, the cost increase directly leads to an increase in the burden on the user. Therefore, it is desirable to take simpler and cheaper measures.

The present invention provides a compressor, a piston, and a connecting rod capable of suppressing loosening of a screw due to creep deformation of a resin in a structure in which a swinging piston made of resin is screwed and fixed.

The present invention includes a plurality of means for solving the above problems. For example, a piston that reciprocates in a cylinder, a valve plate that closes an end of the cylinder, and the piston are supported. A conrod, a crank shaft that applies a rotational force to the end of the conrod, and a crank case that rotatably supports the crank shaft are provided, and the piston swings in the cylinder as the crank shaft rotates. The piston is a swing type that reciprocates while reciprocating, and the piston has at least a surface in contact with the inner peripheral side of the cylinder and a surface on the valve plate side made of a resin having abrasion resistance, and the conrod. The end side fixed to the side has a female screw hole opened on the crank case side, and the outer peripheral surface of the piston is a spherical surface having a diameter smaller than the diameter of the cylinder. do.

According to the present invention, in a structure in which a resin swing piston is screwed and fixed, loosening of a screw due to creep deformation of the resin can be suppressed. Issues, configurations and effects other than those mentioned above will be clarified by the description of the following examples.

It is a figure which shows the structural example of the whole compressor in Example 1 of this invention. It is a figure which shows the structural example of the compressor main body in Example 1. FIG. It is a figure which shows the structural example of the piston in Example 1. FIG. It is a figure which shows the cross-sectional composition example of the piston in Example 1. FIG. It is a figure which shows the other cross-sectional composition example of the piston in Example 1. FIG. It is a figure which shows the example of the cross-sectional structure of the piston in Example 2 of this invention.

Examples of the compressor, piston, and connecting rod of the present invention will be described below with reference to the drawings.

First, the compressor of the present invention can be applied to various compressors that can adopt the swing piston method among compressors that compress various fluids such as air and refrigerant, and the types, models, and uses thereof are particularly limited. Not done.

<Example 1>
Example 1 of the compressor, piston, and connecting rod of the present invention will be described with reference to FIGS. 1 to 4.

First, the overall configuration of the compressor of this embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic view of the compressor according to the first embodiment. Further, FIG. 2 is a diagram showing the internal structure of the compressor main body 1 in FIG. 1.

The compressor 10 shown in FIG. 1 includes a compressor main body 1, an electric motor 2 for driving the compressor main body 1, and a tank 3 for storing the fluid discharged by the compressor main body 1.

The compressor body 1 compresses fluid, and as shown in FIG. 2, the internal structure thereof is a crankcase 21, a cylinder 22 protruding vertically from the crankcase 21, and an end portion of the cylinder 22. It has a valve plate 26 that closes (upper end), a cylinder head 23, and a crankcase 21 that rotatably supports the crankshaft 24 in the center.

In the compressor main body 1, the crankshaft 24 in the crankcase 21 rotates to give a rotational force to one end side of the connecting rod 32, and the piston 33 installed in the cylinder 22 reciprocates in the vertical direction, resulting in a reciprocation. The fluid is sucked from the outside of the cylinder 22, compressed, and discharged to the tank 3.

In FIGS. 1 and 2, for simplification of the description, the compressor shape is a one-cylinder one-stage compressor having only one pair of pistons and cylinders, but a plurality of pistons in series or radially with respect to the crankshaft. -It may be a compressor having a cylinder.

In the compressor main body 1, the crankshaft 24 is arranged and fixed on the tank 3 in a state of being arranged parallel to the rotation shaft of the electric motor 2. Further, a compressor pulley 4 is fixed to the crankshaft 24, and a motor pulley 5 is fixed to the rotating shaft of the motor 2. The compressor pulley 4 attached to the compressor main body 1 has blades, and the cooling air is generated toward the compressor main body 1 as it rotates, thereby promoting heat dissipation of the compressor main body 1.

A transmission belt 6 for transmitting power between the compressor pulley 4 and the motor pulley 5 is wound around the compressor pulley 4 and the motor pulley 5. As a result, according to the rotation of the electric motor 2, the crankshaft 24 of the compressor main body 1 is rotationally driven via the electric motor pulley 5, the transmission belt 6, and the compressor pulley 4, and the compressor main body 1 compresses the fluid.

In FIG. 1, for simplification of the description, the compressor main body 1 is connected to the electric motor 2 via a transmission belt 6, but the crankshaft 24 of the compressor main body 1 and the rotation shaft of the electric motor 2 are cupped. The two may be integrated by directly joining them using a coupling means such as a ring.

Next, the peripheral structure of the piston will be described with reference to FIG. The piston 33 shown in FIG. 2 is a swing piston type in which the piston 33 is integrally formed with the connecting rod 32. In this method, as the crankshaft 24 rotates, the piston 33 reciprocates while swinging in the cylinder 22.

Next, the detailed structure of the piston 33 and the connecting rod 32 will be described with reference to FIGS. 3A to 4. FIG. 3A is a diagram showing a configuration example of the piston, FIG. 3B is a diagram showing a cross-sectional configuration example of the piston, and FIG. 4 is a diagram showing another cross-sectional configuration example of the piston.

The piston 33 shown in FIGS. 3A and 3B is a separate component from the connecting rod 32 that supports the piston 33, and has at least an outer peripheral surface 33a that contacts the inner peripheral side of the cylinder 22 and an upper surface 33c on the valve plate 26 side. It is composed of a resin having abrasion resistance. In this embodiment, the piston 33 is made of a resin having excellent wear resistance except for the piston insert 41 described later.

Examples of the resin material having excellent wear resistance include those using polytetrafluoroethylene (PTFE) as the main body of the piston 33. Further, when the coefficient of thermal expansion is taken into consideration, examples of the resin material of the piston 33 include polyether sulfone (PES) and the like.

Further, the outer peripheral surface 33a of the piston 33 is a spherical surface having a diameter slightly smaller than the diameter on the inner peripheral side of the cylinder 22.

A convex portion 33e is formed on the outer peripheral portion of the surface of the piston 33 on the connecting rod 32 side, and has a structure of fitting with the convex portion 32d of the connecting rod 32.

Further, the piston 33 is molded with a piston insert 41 made of a metal such as an aluminum alloy embedded therein. The piston insert 41 has a shape in which the edge portion 41a bites into the circumferential direction of the piston 33 so that the piston 33 does not come out even when a pulling load is applied to the cylinder head 23 side due to a reciprocating inertial force or a frictional force. It has become.

The piston insert 41 is formed with one or more female screw holes 41c opened on the crankcase 21 side, which is the end side fixed to the connecting rod 32 side, and two in this embodiment, with respect to the connecting rod 32. It is fastened (fixed) with a screw 35 from the crankcase 21 side in a direction orthogonal to the crankshaft 24.

Corresponding to this, in the present embodiment, in the connecting rod 32 shown in FIGS. 3A and 3B, a hole 32c for the screw 35 is provided at a portion of the seating surface supporting the piston 33 that coincides with the female screw hole 41c. Have.

As shown in FIG. 3B, the piston insert 41 of this embodiment has a dish shape with the cylinder head 23 side at the bottom, and the seating surface of the connecting rod 32 is also recessed in the center of the dish shape of the piston insert 41. A recess 32b is formed at the corresponding position. Due to this structure, a hollow portion 41b is formed between the lower surface of the piston insert 41 and the upper surface of the connecting rod 32. The surface of the hollow portion 41b on the valve plate 26 side is covered with the piston insert 41.

The piston 33 uses a piston ring 34 as a seal ring for sealing the compressed gas, and the piston ring 34 is fitted with a certain gap with respect to the ring (annular) groove 33b provided on the outer peripheral surface 33a of the piston 33. ing. The piston ring 34 and the ring groove 33b may not be used.

In this embodiment, the case where the female screw holes 41c of the piston insert 41 are provided at two locations in the direction orthogonal to the crankshaft 24 is described, but the present invention is not limited to this arrangement. For example, a plurality of them may be provided side by side in the direction of the crankshaft 24, and at least one or more may be provided in an oblique direction with respect to the crankshaft 24.

However, considering the direction of the moment when the piston 33 tries to peel off the piston 33 due to the frictional force between the outer peripheral surface 33a and the cylinder inner wall surface 22a when the piston 33 descends, the female screw hole 41c is in the direction orthogonal to the crankshaft 24. It is possible to reduce the pulling force applied to the screw 35 by providing two or more places in the screw 35.

Further, regarding the shape of the piston insert 41, the case where the piston insert 41 has a dish shape with the cylinder head 23 side at the bottom is described in this embodiment, but as in the piston 33A shown in FIG. 4, an insert nut made of metal is described. It may be only 42. Also in this insert nut 42, two or more female screw holes 42c are arranged in a direction orthogonal to the crankshaft 24, and the insert nut 42 is fixed to the connecting rod 32A from the crankcase 21 side with a screw 35.

In this case, it is possible to use a commercially available insert nut, which is cost effective, and the manufacturing process can be simplified by a method such as driving the insert nut after resin molding.

In the case of the form shown in FIG. 4, when the hollow portion 41b as shown in FIG. 3B is formed in order to reduce the reciprocating mass, the resin itself constituting the piston 33 exerts a gas load during the reciprocating movement. It is desirable to take some measures in terms of ensuring strength, as it will be received.

Also in the form shown in FIG. 4, the piston 33A is made of a wear-resistant resin except for the insert nut 42.

Further, as shown in FIGS. 3B and 4, the female screw hole 41c of the piston insert 41 and the female screw hole 42c of the insert nut 42 are provided parallel to the axial direction of the cylinder 22, but the present invention is limited to this arrangement. is not it. For example, the female screw hole can be arranged so as to be inclined with respect to the central axis of the cylinder 22.

Next, the effect of this embodiment will be described.

The pistons 33 and 33A of the first embodiment of the present invention described above are of a swing type that reciprocates while swinging in the cylinder 22 as the crankshaft 24 rotates, and at least on the inner peripheral side of the cylinder 22. The outer peripheral surface 33a in contact with the cylinder and the upper surface 33c on the valve plate 26 side are made of a wear-resistant resin, and on the end side fixed to the connecting rod 32 side, a female screw hole 41c opened on the crankcase 21 side, It has 42c, and the outer peripheral surface 33a is a spherical surface having a diameter smaller than the diameter of the cylinder 22.

As a result, the axial force of the screw 35 that fixes the piston 33 to the connecting rod 32 is received by the seating surface 32a of the connecting rod 32, so that problems such as loosening due to creep deformation of the resin do not occur in fastening and fixing with the screw 35. can do. Therefore, in the swing piston method, the effect of smooth sliding is obtained by maintaining a minute gap between the outer peripheral surfaces of the pistons 33 and 33A and the inner wall surface of the cylinder 22, and the resin creep countermeasure is simplified. Moreover, it can be taken at low cost. From these effects, the compressor can be operated stably for a long time.

Further, inside the pistons 33 and 33A, a piston insert 41 or an insert nut 42 having female screw holes 41c and 42c is provided, and the piston insert 41 or the insert nut 42 is screwed from the crankcase 21 side with respect to the connecting rod 32. Since it is fixed by 35, the resin pistons 33 and 33A can be firmly fixed to the connecting rod 32 by the piston insert 41 or the insert nut 42, so that more stable operation can be performed.

Further, the piston insert 41 or the insert nut 42 is made of metal, and the pistons 33 and 33A are made of resin except for the piston insert 41 or the insert nut 42, so that the pistons 33 and 33A are made of resin with respect to the connecting rod 32. It can be fixed more firmly and smooth sliding motion is possible.

Further, since two or more female screw holes 41c and 42c are arranged in the direction orthogonal to the crankshaft 24, the pistons 33 and 33A formed on the spherical surface are stably fixed to the connecting rod 32 in the circumferential direction. This makes it possible to fix the connecting rod 32 more firmly, so that more stable operation can be performed.

Further, since the female screw holes 41c and 42c are arranged so as to be inclined with respect to the central axis of the cylinder 22, a wide space for the tool to enter can be secured in the tightening work of the screw 35, so that the assembling property can be improved. ..

Further, since the hollow portion 41b is formed between the piston 33 and the connecting rod 32, the mass of the reciprocating portion including the piston 33 can be reduced, so that the compressor body vibrates due to the reciprocating inertial force. Can be improved.

Further, since the surface of the hollow portion 41b on the valve plate 26 side is covered with the piston insert 41, the piston 33 can be held from the inside by the piston insert 41, and when the hollow portion 41b is formed. However, it is possible to reduce the amount of deformation such as shrinkage of the piston 33 during molding and expansion due to compression heat during operation.

Further, since the piston insert 41 has an edge portion 41a extending in the circumferential direction of the piston 33, the piston insert 41 receives a pulling load on the cylinder head 23 side due to reciprocating inertial force or frictional force. Can be prevented from coming out of the piston 33, so that the piston 33 can be more stably fixed to the connecting rod 32.

<Example 2>
The compressor, piston, and connecting rod of Example 2 of the present invention will be described with reference to FIG. The same reference numerals are shown in the same configurations as in the first embodiment, and the description thereof will be omitted. The same applies to the following examples. FIG. 5 is a diagram showing a cross-sectional configuration example of the piston in the second embodiment.

This embodiment has a configuration in which the material cost of the piston is further reduced as compared with the first embodiment. This will be described below with reference to FIG.

In the first embodiment, as shown in FIG. 3B, the entire periphery of the piston insert 41 or the insert nut 42 is made of a resin having excellent wear resistance. However, resin materials that are excellent in wear resistance and are used especially for sliding / sealing parts of compressors are generally expensive, including PTFE, and are as much as possible in consideration of the user's burden as the above-mentioned periodic replacement parts. It is desired to reduce the volume.

When considering the function of the piston for each part, the sliding performance is required only for the outer peripheral surface that slides with the inner wall surface 22a of the cylinder, and for the other parts, the heat insulating property is particularly provided on the upper surface 33c. Just do it.

Therefore, in this embodiment, as shown in FIG. 5, the piston 33B is a separate part from the piston cover 43 forming the surface on the valve plate 26 side and the piston cover 43, and is an outer peripheral surface of the piston 33B. It has a structure having an outer peripheral portion 45 constituting 45a.

The piston cover 43 is made of an inexpensive resin having excellent heat resistance, such as phenol resin, unlike the outer peripheral surface 45a made of a resin having wear resistance. As the resin constituting the outer peripheral surface 45a, it is desirable to use the same material as the resin constituting the piston 33 of the first embodiment described above.

Of the piston 33B, a piston insert 44 made of metal having a female screw hole 43c provided on the surface on the crankcase 21 side is cast inside the piston cover 43, and the piston insert 44 is on the crankcase 21 side. The surface of the piston 33B is screwed to the connecting rod 32 so as to sandwich the convex portion 33e on the inner peripheral surface of the piston 33B.

Also in this embodiment, the piston insert 44 has a dish shape with the cylinder head 23 side at the bottom, and the seating surface of the connecting rod 32 also has a recess 32b at a position corresponding to the center recess of the dish shape of the piston insert 44. Is formed, and the hollow portion 43b is formed.

The surface of the hollow portion 43b on the valve plate 26 side is covered with the piston insert 44.

The axial force of the screw 35 works to tighten the center 33d of the piston 33, but in this structure, a much wider pressure receiving area can be secured than when simply fixing with the screw 35, so that creep deformation is greatly reduced. It is possible to prevent the screw 35 from loosening.

Other configurations and operations are substantially the same as those of the compressor, piston, and connecting rod of the first embodiment described above, and details will be omitted.

Also in the compressor provided with the piston 33B having the piston cover 43 forming the surface on the valve plate 26 side of the second embodiment of the present invention and the outer peripheral portion 45 forming the outer peripheral surface 45a, the above-described embodiment is also performed. The same effect as that of the compressor of Example 1 can be obtained.

Further, a piston insert 44 having a female screw hole 43c is provided inside the piston cover 43, and the piston insert 44 is fixed to the connecting rod 32 from the crankcase 21 side with a screw 35. Since the resin piston 33B can be firmly fixed to the connecting rod 32 by the insert 44, more stable operation can be performed.

Further, the piston insert 44 is made of metal, the piston cover 43 is made of a heat-resistant resin, and the outer peripheral portion 45 is made of a wear-resistant resin, which makes it expensive to wear. It is possible to reduce the volume of the excellent resin, and it is possible to obtain the merit that the cost of the entire piston 33B can be suppressed as compared with the first embodiment.

<Others>
The present invention is not limited to the above examples, and includes various modifications. The above-mentioned examples have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations.

It is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

1 ... Compressor body 2 ... Electric 3 ... Tank 4 ... Compressor pulley 5 ... Electric pulley 6 ... Transmission belt 10 ... Compressor 21 ... Crank case 22 ... Cylinder 22a ... Cylinder inner wall surface 23 ... Cylinder head 24 ... Crankshaft 26 ... Valve plate 32, 32A ... Conrod 32a ... Seat surface 32b ... Recessed portion 32c ... Hole 32d ... Convex portion 33, 33A, 33B ... Piston 33a ... Outer peripheral surface 33b ... Ring groove 33c ... Top surface 33d ... Center 33e ... Convex portion 34 ... Piston ring 35 ... Screw 41 ... Piston insert 41a ... Edge 41b ... Hollow part 41c ... Female screw hole 42 ... Insert nut 42c ... Female screw hole 43 ... Piston cover 43b ... Hollow part 43c ... Female screw hole 44 ... Piston insert 45 ... Outer circumference 45a ... Outer circumference surface

Claims (13)

A piston that reciprocates in the cylinder and
A valve plate that closes the end of the cylinder,
The connecting rod that supports the piston and
A crankshaft that applies a rotational force to the end of the connecting rod,
A crankcase that rotatably supports the crankshaft, and
The piston is a swing type that reciprocates while swinging in the cylinder as the crankshaft rotates.
The piston
At least, the surface in contact with the inner peripheral side of the cylinder and the surface on the valve plate side are made of a resin having wear resistance, and the end side fixed to the connecting rod side is on the crankcase side. It has an open female screw hole and
A compressor characterized in that the outer peripheral surface of the piston is a spherical surface having a diameter smaller than the diameter of the cylinder. In the compressor according to claim 1,
An insert having the female screw hole is provided inside the piston.
A compressor characterized in that the insert is fixed to the connecting rod from the crankcase side with a screw. In the compressor according to claim 2,
The insert is made of metal
A compressor characterized in that the piston is made of the resin except for the insert. In the compressor according to claim 1,
The compressor is characterized by having a piston cover forming a surface on the valve plate side and an outer peripheral portion forming the outer peripheral surface. In the compressor according to claim 4,
An insert having the female screw hole is provided inside the piston cover.
A compressor characterized in that the insert is fixed to the connecting rod from the crankcase side with a screw. In the compressor according to claim 5,
The insert is made of metal
The piston cover is made of a heat-resistant resin.
A compressor characterized in that the outer peripheral portion is made of the wear-resistant resin. In the compressor according to claim 1,
A compressor characterized in that two or more female screw holes are arranged in a direction orthogonal to the crankshaft. In the compressor according to claim 1,
A compressor characterized in that the female screw holes are arranged so as to be inclined with respect to the central axis of the cylinder. In the compressor according to claim 2 or 5,
A compressor characterized in that a hollow portion is formed between the piston and the connecting rod. In the compressor according to claim 9,
A compressor characterized in that the surface of the hollow portion on the valve plate side is covered with the insert. In the compressor according to claim 2,
The compressor is characterized in that the insert has an edge extending in the circumferential direction of the piston. A swing-type piston that reciprocates while swinging in the cylinder as the crankshaft rotates.
At least, the surface in contact with the inner peripheral side of the cylinder and the surface on the valve plate side are made of a wear-resistant resin.
The end side fixed to the connecting rod side has a female screw hole opened on the crankcase side.
A piston characterized in that the outer peripheral surface is a spherical surface having a diameter smaller than the diameter of the cylinder. A connecting rod having a seat surface for supporting the piston according to claim 12 and a hole for a screw at a position corresponding to the female screw hole on the seat surface.

Images