JP2010007483A - Reciprocating hermetic compressor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the reliability of a sliding surface by reducing sliding resistance between a connecting rod and a crankshaft in a reciprocating hermetic compressor. <P>SOLUTION: This reciprocating hermetic compressor comprises a piston, the connecting rod, and the crankshaft. The piston side end of the connecting rod is connected to the piston through a spherical seat. A cylindrical through-hole is formed at the crankshaft side end of the connecting rod. The crankshaft comprises a cylindrical eccentric section which is fitted into the through-hole of the connecting rod. The connection section between the crankshaft side end of the connecting rod and the eccentric section of the crankshaft has a portion which is larger in gap toward the opening of the through-hole. An arcuate shape according to the center-to-center distance of the connecting rod may be provided to the inner wall of the through-hole. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a reciprocating hermetic compressor used in a refrigerator / freezer such as a household refrigerator or a showcase.

  In a reciprocating hermetic compressor, an electric motor and a compression mechanism are housed in a hermetic container (see Patent Document 1). The compression mechanism has an eccentric part that rotates eccentrically at the upper end of the crankshaft supported by the frame. The piston that reciprocates in the cylinder is connected to the eccentric portion via a connecting rod.

In some reciprocating hermetic compressors, a connecting rod and a piston are connected via a ball joint. Since this structure uses a spherical seat for the connecting part, even if an error occurs between the axis of the frame, that is, the journal part of the crankshaft and the axis of the cylinder that controls the reciprocation of the piston, the spherical seat By freely swinging and aligning, the reciprocating motion of the piston is not hindered and can be moved smoothly.
Japanese Patent Publication No. 2-36794

  However, in the reciprocating compressor using the ball joint as described above, the sliding reliability of the connecting portion between the connecting rod and the eccentric portion of the crankshaft is poor, and the compression resistance is large, so the compression efficiency may be reduced. is there. In particular, a connecting rod using a ball joint is likely to be inclined, and is in an edge contact at a connecting portion, so that slidability is likely to be reduced.

  An object of the present invention is to improve the sliding reliability of a connecting portion between a connecting rod and an eccentric portion of a crankshaft in a reciprocating hermetic compressor employing a ball joint for connecting a piston and a connecting rod. And

  In order to solve the above-described problems, in the present invention, the connecting portion between the inner diameter portion of the connecting rod and the eccentric portion of the crankshaft is shaped so as to reduce the contact stress.

  For example, the reciprocating hermetic compressor of the present invention includes a piston, a connecting rod, and a crankshaft. The end of the connecting rod on the piston side is connected to the piston via a spherical seat. A cylindrical through hole is provided at an end of the connecting rod on the crankshaft side. The crankshaft includes a cylindrical eccentric portion, and the eccentric portion is fitted in the through hole. There is a portion where the gap between the end of the connecting rod on the crankshaft side and the eccentric portion of the crankshaft becomes larger as it is closer to the opening of the through hole.

  In the processing of the inner wall of the through-hole, when the inner diameter diameter direction is the x-axis direction and the inner diameter longitudinal direction is the z-axis direction, A curved surface can be imparted to the inner wall of the through hole of the connecting rod by cutting the grindstone in the axial direction.

  According to the present invention, in a reciprocating hermetic compressor that employs a ball joint for connecting a piston and a connecting rod, the sliding reliability of the connecting portion between the connecting rod and the eccentric portion of the crankshaft is improved. Can do.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of a reciprocating hermetic compressor. FIG. 2 is a schematic view of the periphery of the connecting rod 2. FIGS. 3A and 3B are diagrams showing the operation of the connecting rod 2 when reversing the reciprocating motion. The reciprocating hermetic compressor used in the refrigeration cycle is placed in a hermetic container (pressure chamber) 12. An electric motor 16 and a compression mechanism unit 17 are provided. The electric motor 16 and the compression mechanism portion 17 are supported by the frame 4. The electric motor 16 includes a rotor 9 and a stator 11. The compression mechanism unit 17 includes a piston 1, a cylinder 5, a crankshaft 8, a connecting rod 2, and the like.

  The piston 1 is reciprocally installed in a cylinder 5 installed on the frame 4. The piston 1 includes a spherical seat 1a. The spherical seat 1a is formed of a spherical surface that is recessed and opened toward the connecting rod 2 side.

  The crankshaft 8 is supported by the frame 4. A cylindrical eccentric portion 3 is provided at the upper end of the crankshaft 8.

  The connecting rod 2 includes a rod member 2b, a spherical portion 2a coupled to one end of the rod member 2b, and a ring portion 2c coupled to the other end of the rod member 2b.

  The spherical body portion 2 a is fitted into the spherical seat 1 a of the piston 1 and constitutes a ball joint 14. By this ball joint 14, the piston 1 can be reciprocated with respect to the cylinder 5.

  The ring portion 2c has a cylindrical through hole 2h. The eccentric portion 3 of the crankshaft 8 is fitted into the through hole 2h. The eccentric part 3 can slide with respect to the inner diameter part (inner wall part of the through hole 2h) 3d. The ring portion 2 c is rotatable around the cylindrical axis of the eccentric portion 3.

  The rotational force of the electric motor 16 composed of the stator 11 and the rotor 9 attached to the sealed container 12 via the spring 10 is transmitted to the crankshaft 8, and the piston 1 is moved by the eccentric portion 3 at the upper end via the connecting rod 2. A reciprocating motion is performed in the cylinder 5.

  A cylinder head 7 is attached to the cylinder 5 via a valve plate 6. In synchronization with the reciprocating motion of the piston 1, a valve (not shown) opens and closes to compress the fluid guided from the outside of the hermetic container 12.

  Sliding between the piston 1 and the cylinder 5, between the connecting rod 2 and the eccentric part 3, between the crankshaft 8 and the bearing part of the frame 4, or between the spherical seat 1a and the spherical part 2a The part is lubricated by lubricating oil (not shown) stored in the sealed container 12 when the compressor is in operation.

  Lubricating oil is pumped from the lower part of the hermetic container 12 through an oil supply hole (not shown) formed continuously in the crankshaft 8 over the entire length of the shaft, and supplied to the sliding portion. ing. For pumping up the lubricating oil, there are a method of forcibly adding a trochoid pump and a method of supplying oil by operating the rotational force of the crankshaft 8 as a centrifugal pump. In this embodiment, a centrifugal pump is used.

  As described above, the connecting rod 2 and the piston 1 are connected via the ball joint 14. Therefore, even if an error occurs between the axis of the journal of the frame 4, that is, the crankshaft 8, and the axis of the cylinder 5 that controls the reciprocation of the piston 1, the spherical seat 1a freely swings and aligns. As a result, the reciprocating motion of the piston 1 is not disturbed and moves smoothly.

  In such a reciprocating compressor, it is important to reduce the sliding resistance of all parts that move relatively in order to improve the reliability of the sliding portion and to increase the efficiency of the compressor.

  However, in the compressor using the spherical seat, the sliding reliability is poor at the portion where the connecting rod 2 and the eccentric portion 3 of the crankshaft 8 are in contact with each other, and the efficiency of the compressor is reduced due to the large sliding resistance. May end up. This will be specifically described below.

  In the reciprocating compressor using the spherical seat, the inner diameter portion 2d of the connecting rod 2 moves in the state shown in FIG. 3 when the reciprocating motion of the piston is reversed. That is, it reciprocates in the vertical direction X in the figure by a dimension determined by the inclination of the shaft center (manufacturing error) and the eccentric amount of the crankshaft 8.

  FIG. 4 is a diagram for explaining that the connecting rod 2 receives a couple due to the fitting clearance between the connecting rod 2 and the eccentric portion 3.

  Since the lubricating oil is not supplied when the reciprocating compressor is stopped, the connecting rod 2 is indicated by an arrow E in the drawing due to gravity within the range of the fitting clearance for assembly as shown in FIG. Leaning in the direction of the couple. In particular, due to the difference in weight between the spherical portion 2a and the ring portion 2c, the balance is lost and the inclination tends to increase.

  At the start of operation, the edge of the inner diameter portion 2d of the connecting rod 2 is in contact with the eccentric portion 3 of the crankshaft 8 as shown in FIG. 4, and the edge portion slides until the lubricating oil is supplied at the start of operation. It will be.

  During normal operation, since the lubricating oil is supplied to the fitting portion (between the eccentric portion 3 and the inner diameter portion 2d) and an oil film is formed, the edge does not contact. However, at the time of reversing the piston, that is, at the top dead center and the bottom dead center of the piston, the direction of the force applied to the rod is reversed, so that edge contact may occur or the lubricating oil film may be interrupted. When the reciprocating motion of the piston is reversed, an excessive force is generated in the fitting portion, the sliding resistance is increased, and the efficiency of the compressor may be reduced or the sliding surface may be seized.

  For this reason, in a reciprocating compressor using a spherical seat, the sliding portion between the eccentric portion 3 of the crankshaft 8 and the inner diameter portion 2d of the connecting rod 2 causes abnormal wear, resulting in deterioration of performance, There may be a problem that the motor stops.

  Therefore, in the embodiment to which the present invention is applied, the shape of the sliding portion is configured so that the contact stress is reduced, thereby solving this problem.

  Specifically, in the embodiment to which the present invention is applied, the connection portion between the ring portion 2c of the connecting rod 2 and the eccentric portion 3 of the crankshaft 8 is closer to the opening portion of the through hole h of the ring portion 2c. The gap is increased.

  Specific examples will be described below.

<First embodiment>
FIG. 5 is a schematic view of the periphery of the connecting rod 2. As shown in the figure, the inner diameter portion 2d of the ring portion 2c of the connecting rod 2 (the inner wall portion of the through hole 2h) is a curved surface having a circular cross section (a cross section by a plane including the cylindrical axis). That is, the inner diameter portion 2d of the connecting rod 2 has a larger inner diameter as it is closer to the opening of the through hole 2h.

The curved surface is
R = LD / 2
L: Distance between the center of the spherical part 2a (the center of the spherical seat 1c) and the center of the inner diameter part 2d of the ring part 2c D: The radius of curvature is smaller than an arc having a radius determined by the diameter of the inner diameter part 2d of the ring part 2c. . Note that L can be a distance between the center of the spherical portion 2a and the center of the inner diameter portion 2d of the thickest portion near the center of the ring portion 2c. D can be the diameter of the thickest portion near the center of the ring portion 2c.

  Specifically, the diameter of the eccentric portion 3 of the crankshaft 8 and the diameter of the inner diameter portion 2d near the center of the ring portion 2c of the connecting rod 2 are each 14 mm, and the length of the inner diameter portion 2d (the length of the through hole 2h) ) Was set to 14 mm, and R (curvature radius) of the arc shape of the inner diameter portion 2d was set to 33 mm.

  The compressor using the connecting rod 2 has a higher reliability of the sliding portion than the compressor using the connecting rod (see FIG. 4) in which the arc shape is not given to the inner diameter portion 2d. The efficiency of the machine was also good.

<Manufacturing method>
A method for forming the inner diameter portion 2d of the ring portion 2c of the connecting rod 2 shown in FIG. 5 will be described with reference to FIG.

  In this forming method ((A) to (C)), the connecting rod 2 is gripped and rotated by a chuck mechanism (not shown) that rotates around the inner diameter portion 2d. On the other hand, the grindstone 13 that similarly rotates is pressed against the inner diameter portion 2d of the connecting rod 2 and ground. At this time, unlike general internal grinding, grinding is performed by tilting the grindstone axis by θ with respect to the cutting direction.

According to this method, as shown in FIG. 6, it is possible to process the inner diameter with a curved shape corresponding to the inclination angle θ. In this method, assuming that the arc shape of the inner diameter portion 2d of the connecting rod 2 is R (z), the arc that can be machined with the diameter of the grindstone being ρ, the inner diameter dimension of the connecting rod 2 being R ₀ , and the inclination angle of the grindstone axis being θ. Shape is radius of curvature R (z) = ρ + ((R ₀ −ρ) ² + z ² tan ² θ) ^1/2
Can be expressed as

  FIG. 7 shows an example of the relationship between the arc shape that can be machined when the grindstone diameter is 12 mm and the diameter of the inner diameter portion 2d of the connecting rod 2 is 14 mm, and the position of the inner diameter portion 2d. That is, according to this method, it is possible to set a necessary arc shape simply by inclining the grindstone shaft, and it is possible to easily produce a connecting rod having a desired arc shape. In addition, the manufacturing method and assembly procedure of components other than the connecting rod are as known.

<Second embodiment>
FIG. 8 is a schematic view of the periphery of the connecting rod 2 according to the second embodiment. In this embodiment, the eccentric portion 3 of the crankshaft 8 has a barrel shape in which the central portion swells. That is, the eccentric portion 3 has a smaller outer diameter as it is closer to the opening of the through hole 2h. By carrying out like this, in the fitting part of the ring part 2c and the eccentric part 3, a clearance gap can become large, so that it is close to an opening part.

Specifically, the outer diameter part of the eccentric part 3 (cylindrical part constituted by the outer wall of the eccentric part 3) has a curved surface whose cross section (cross section by a plane including the cylindrical axis) has an arc shape. ,
R = LD / 2
L: Distance between the center of the spherical portion 2a (spherical seat 1a) and the center of the inner diameter portion 2d of the ring portion 2c. D: The radius of curvature is smaller than an arc having a radius determined by the diameter of the inner diameter portion 2d of the ring portion 2c. Note that L can be a distance between the center of the spherical portion 2a and the center of the inner diameter portion 2d of the thickest portion near the center of the ring portion 2c. D can be the diameter of the thickest portion near the center of the ring portion 2c.

  The reciprocating compressor using the crankshaft 8 provided with the eccentric portion 3 has high sliding reliability and good compressor efficiency, as in the first embodiment.

<Third embodiment>
FIG. 9 is a sectional view of the connecting rod 2 according to the third embodiment. In this embodiment, a groove 2e for refueling is provided in the inner diameter portion 2d of the ring portion 2c of the connecting rod 2. The groove 2e is a ring-shaped recess formed along the inner wall substantially at the center of the inner diameter portion 2d of the ring portion 2c. Even in such a case, it is desirable to avoid edge contact between the inner diameter portion 2 c and the eccentric portion 3. However, slightly different from the first embodiment, the center of the arc-shaped R to be applied to the inner diameter portion 2d is shifted in the direction parallel to the cylindrical axis by 1/2 of the groove width W in accordance with the width of the groove 2e. Position. In the example of FIG. 9, the cross-sectional arc of the inner diameter portion 2 c above the groove 2 e is shifted from the center O of the spherical portion 2 a by the center Ou of the curvature radius by W / 2 on the upper side. Further, the cross-sectional arc of the inner diameter portion 2c below the groove 2e has a center of curvature Od shifted from the center O of the spherical portion 2a by W / 2 on the lower side. The range of the radius of curvature is the same as that in the first embodiment.

  The compressor using the connecting rod 8 has a higher reliability of the sliding portion as compared with a compressor using a conventional connecting rod that does not have an arc shape while providing an oil supply groove on the inner diameter portion. The compressor efficiency was also good.

  The present invention has been described with reference to several embodiments. In addition, this invention is not limited to the said Example, A various deformation | transformation is possible.

  For example, the first embodiment (or the third embodiment) and the second embodiment may be combined. That is, a curved surface having a circular arc shape in section may be formed in the inner diameter portion 2d of the ring portion 2c, and a curved surface having a circular arc shape in cross section may also be formed in the eccentric portion 3 of the crankshaft 8. Even in this case, edge contact between the inner diameter portion 2d and the eccentric portion 3 can be effectively avoided.

  Further, the curved surface applied to the inner diameter portion 2d and the eccentric portion 3 does not have to be a strict arc shape. The inner diameter portion 2d may have a shape in which the inner diameter is gradually increased toward the opening direction of the through hole 2h. For example, the cross section may have a tapered shape with rounded corners. In the eccentric part 3, what is necessary is just the shape which made the outer diameter gradually small toward the opening direction of the through-hole 2h. For example, the cross section may have a tapered shape with rounded corners.

  The present invention is a technique for improving the sliding reliability of a reciprocating compressor using a spherical seat at a low cost, and is applicable not only to refrigerators and freezers but also to similar products in general.

Sectional drawing of a reciprocating type hermetic compressor. Schematic around the connecting rod. The figure explaining the movement state of a connecting rod. The figure which shows the contact state of a connecting rod. The block diagram of a 1st Example. The figure which shows the manufacturing method of a connecting rod internal-diameter part. The figure which shows the relationship between a grindstone axis inclination angle and the circular arc shape of the internal diameter part of a connecting rod. The block diagram of the 2nd Example. The block diagram of a 3rd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Piston 1a ... Spherical seat 2 ... Connecting rod 2a ... Spherical part 2b ... Rod member 2c ... Ring part 2d ... Inner diameter part 2h ... Through hole 8 ... Crankshaft 3 ... Eccentric part 4 ... Frame 5 ... Cylinder 6 ... Valve plate 7 ... Cylinder head 8 ... Crankshaft 9 ... Rotor 10 ... Spring 11 ... Stator 12 ... Pressure chamber 13 ... Processing tool (grinding stone)
14 ... Ball joint part

Claims (9)

A piston, a connecting rod and a crankshaft;
The piston side end of the connecting rod is connected to the piston via a spherical seat,
At the end of the connecting rod on the crankshaft side, there is a cylindrical through hole,
The crankshaft includes a cylindrical eccentric portion, and the eccentric portion is fitted in the through hole,
The connecting portion between the crankshaft side end portion of the connecting rod and the eccentric portion of the crankshaft has a portion in which a gap becomes larger as it is closer to the opening portion of the through hole. Reciprocating hermetic compressor. The reciprocating hermetic compressor according to claim 1,
A reciprocating hermetic compressor, wherein an end of the connecting rod on the crankshaft side has a portion in which the inner diameter of the through hole becomes larger as it is closer to the opening of the through hole. A reciprocating hermetic compressor according to claim 1 or 2,
The eccentric portion has a portion whose outer diameter is smaller as it is closer to the opening of the through hole.
This is a reciprocating hermetic compressor. A reciprocating hermetic compressor according to any one of claims 1 to 3,
The reciprocating hermetic compressor, wherein an inner wall of the through hole has a curved surface having a circular cross section. A reciprocating hermetic compressor according to claim 4,
A groove is formed in the inner wall of the through hole,
The reciprocating hermetic compressor, wherein the curved surface has an arc shape centered on a radius of curvature at a position shifted according to the width of the groove. A reciprocating hermetic compressor according to any one of claims 1 to 5,
The eccentric portion is
A reciprocating hermetic compressor comprising a curved surface having a circular cross section. A reciprocating hermetic compressor according to claim 4,
The curved surface of the inner wall of the through hole is
R = LD / 2
(However, L is the distance between the center of the spherical seat and the center of the inner diameter part of the through hole at the crankshaft side end, and D is the diameter of the inner diameter part)
A curved surface having a smaller radius of curvature than an arc of a radius determined by
This is a reciprocating hermetic compressor. A reciprocating hermetic compressor according to claim 6,
The curved surface of the eccentric part of the crankshaft is
R = LD / 2
(However, L is the distance between the center of the spherical seat and the center of the inner diameter part of the through hole at the crankshaft side end, and D is the diameter of the inner diameter part)
A reciprocating hermetic compressor having a curved surface having a smaller radius of curvature than an arc of a radius determined by It is a manufacturing method of the reciprocating type hermetic compressor according to claim 2,
In the processing of the inner wall of the through hole at the end of the connecting rod on the crankshaft side,
Connecting rod by cutting the grindstone in the x-axis direction while tilting the grindstone axis in the y-axis direction orthogonal to the x and z-axis when the inner diameter diameter direction is the x-axis direction and the inner diameter longitudinal direction is the z-axis direction A method of manufacturing a reciprocating hermetic compressor, wherein a curved surface is formed on the inner wall of the through hole.

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