JP2007064199A - Hermetically sealed compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compressor increased in efficiency by reducing sliding loss. <P>SOLUTION: In this hermetically sealed compressor, compression elements and electric elements are stored in a hermetically sealed container, and a crankshaft 7 driven by the electric elements is connected to a piston 4 through a connecting rod 2 by a ball joint structure. The ball joint structure comprises an inner spherical surface 4a formed on the piston 4, a spherical body part 2a formed on the connecting rod 2, and a rotation restriction part 10d formed separately from the piston 4 and the connecting rod 2. The rotation restriction part 10d is installed on the piston 4 side but the connecting rod 2 side to restrict the relative rotation of the piston 4 and the connecting rod 2. A ferrous sintered material sealed by an oxide film is used for the piston 4 and the connecting rod 2. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hermetic compressor used for a refrigerator, a room air conditioner, and the like, and more particularly, to a hermetic compressor having a reciprocating piston.

  In a hermetic compressor having a reciprocating piston, a structure is used in which the crankshaft and the piston are connected by a connecting rod to change the rotational movement of the shaft into a reciprocating movement. Among these, as a connecting structure of the piston and the connecting rod, a structure connected by a radial bearing as described in Patent Document 1 is known.

  In Patent Document 1, a piston pin is used for a connecting portion between a piston and a connecting rod, and both are connected as a bearing structure in which the piston pin serves as a shaft.

  As another connection structure of the piston and the connecting rod, a so-called ball joint structure connected by a spherical bearing as in Patent Document 2 and Patent Document 3 is known. As what is connected as a ball joint structure, the structure which shape | molded the inner spherical surface provided in a piston by plastic working like patent document 2 is known. Further, in Patent Document 3, a part of the inner spherical surface of the piston and a part of the outer spherical surface of the connecting rod are both deleted, and after inserting the outer spherical part of the connecting rod into the inner spherical part of the piston, The piston is connected.

  Further, in Patent Document 2, a spherical bearing of a ball joint structure is subjected to nitriding treatment and / or manganese phosphate treatment, and a high carbon chromium steel material is used for the spherical surface. Patent Document 4 shows an example in which a piston connected by a ball joint type is formed by sintering.

JP 2004-27969 A JP 2003-214343 A Japanese Patent Laid-Open No. 2003-184751 JP-A 64-69862

  Among the above-described conventional examples, Patent Document 1 uses a piston pin to connect a piston and a connecting rod. This connecting structure has a piston pin inserted on the piston side as a shaft portion and a bearing portion on the connecting rod side. is doing. Therefore, when the piston side shaft is inclined and inserted into the connecting rod side bearing, there may be a problem with respect to sliding. That is, the sliding portion between the piston pin and the connecting rod becomes local, and at this time, the contact surface pressure between the two becomes excessive, so that the reliability may be lowered due to wear of the sliding portion. In Patent Document 1, the supply of lubricating oil is stabilized to improve the reliability, but it does not solve the localization itself of the sliding portion caused by the bearing structure.

  On the other hand, Patent Document 2 and Patent Document 3 adopt a structure in which a piston and a connecting rod are connected by a ball joint method. According to the ball joint connection, sliding and wear between the piston pin and the connecting rod do not cause a problem as in Patent Document 1.

  In Patent Document 2, since the ball seat provided on the piston is molded by plastic working, the above-described problem does not occur, but the sliding between the piston and the connecting rod may cause a problem. In other words, in order to secure the connected state, the ball seat portion is processed in the closing direction, so that the passage of the lubricating oil supplied to the connecting portion becomes narrow and the lubricating oil may not flow sufficiently. Therefore, inflow and outflow of the lubricating oil to the connecting portion cannot be sufficiently secured, and there is a possibility that the temperature of the spherical bearing portion is increased and damaged.

  On the other hand, Patent Document 3 has a structure having a flat portion obtained by cutting a part of the spherical portion of the connecting rod, and the two are connected by rotating the spherical portion of the connecting rod after inserting the spherical portion on the piston side. . Although this configuration can secure a space for supplying the lubricating oil, there is a problem that the connection is released when the spherical portion rotates relative to the piston. Therefore, in Patent Document 3, a rotation restricting member is provided to prevent the release of the connection. For example, in the rotation restricting member having the structure shown in FIG. 12 of Patent Document 2, the stopper, which is the rotation restricting member, slides between the piston and the piston. May move and generate noise. Further, in the structure of FIGS. 13 and 15, since the stopper is held only by the frictional force, the frictional force changes when the force of rotating the piston is applied during operation, and the connecting rod stopper can come off. There is sex.

  In addition, when a high carbon chrome steel material is used for the spherical surface (ball) as in Patent Document 2, there is a problem in workability because the hardness of the high carbon chrome steel material is high. That is, a material that has not only high wear resistance but also excellent workability has been demanded. In addition, when such a hard material is used, in Patent Document 2, it is difficult to integrally form the connecting rod due to workability problems. Therefore, in order to make the shape of the spherical surface serving as the coupling portion with the piston close to a perfect circle, a step of separately forming the rod portion and the sphere portion and then connecting them is necessary. At this time, the production efficiency may be reduced.

  On the other hand, if the spherical portion and the rod portion are formed integrally, it is difficult to maintain the accuracy of the spherical portion, so that not only the loss on the sliding surface of the piston is likely to occur, but also the reliability decreases due to the progress of wear. There was a fear.

  The present invention is intended to solve the above-described problems that may occur in the conventional example. In a ball joint type hermetic compressor in which a piston and a rod are connected by a spherical bearing, reliability is ensured or sliding loss is achieved. An object of the present invention is to provide a compressor with improved efficiency by reducing the above.

In order to achieve the above object, a hermetic compressor in which a compression element and an electric element are housed in a hermetic container, and a crankshaft and a piston driven by the electric element are connected with a ball joint structure by a connecting rod,
The ball joint structure of the present invention includes an inner spherical surface provided in the piston, a sphere portion provided in the connecting rod, and a rotation restricting portion that is a separate member from the piston and the connecting rod, and the rotation restricting portion is attached to the piston, The relative rotation with the connecting rod was restricted.

In order to achieve the above object, according to the present invention, a compression element and an electric element are housed in a hermetically sealed container, and a crankshaft that transmits a rotational force from the electric element is opened to the crankshaft side. A piston having an inner spherical surface, and a connecting rod having a spherical portion connected to the inner spherical surface as one end and a bearing portion connected to the crankshaft as the other end and a rod portion connecting these both ends, the inner spherical surface comprising The central angle of the horizontal arc is formed larger than the central angle of the vertical arc, and the spherical portion has a small size portion that is smaller than the horizontal opening size of the inner spherical surface. A hermetic compressor in which the sphere part is connected with a ball joint structure,
Provided with a rotation restricting portion for restricting relative rotation between the connecting rod and the piston at a position facing the small dimension portion,
The rotation restricting portion is attached to the piston, and can be brought into contact with the small dimension portion of the spherical body portion during the relative rotation.

  In the above-described hermetic compressor, the small dimension part is formed by plane parts parallel to each other, and the dimension between the plane parts has the same dimension as a part having a dimension smaller than the diameter of the arc, The rotation restricting portion has a convex shape having a planar shape facing the planar portion.

  Further, an elastic portion is provided between the rotation restricting portion and the inner peripheral surface in the opening of the piston, and the rotation restricting portion is held by an elastic force from the elastic portion.

  The elastic portion and the rotation restricting portion are provided as a part of a retaining member constituted by one member, and the retaining member extends toward the inner peripheral surface in the opening of the piston. The end portion of the extending portion is held by entering the groove provided on the inner peripheral surface of the piston.

  The elastic portion is a spring member having a curved outer peripheral surface that abuts the inner peripheral surface of the piston, and a shape that follows the inner peripheral surface of the piston.

  Further, the elastic part and the rotation restricting part are disposed on both upper and lower sides of the connecting rod, and the dimension between the upper rotation restricting part and the lower rotation restricting part is larger than the small dimension part, The part generates force in the direction of sandwiching the sphere part with respect to these rotation restricting parts.

  Moreover, the spring member which comprises an elastic part shall be comprised with the spring arrange | positioned in multiple numbers by the circumferential direction of the internal peripheral surface of a piston.

  Further, the elastic part and the rotation restricting part located above and the elastic part and the rotation restricting part located below are connected by a support part, and the elastic part, the rotation restricting part and the support part are formed as one member. It was supposed to be composed.

  Further, the extending portion of the retaining member is provided on the support portion.

Furthermore, in order to achieve the above object, the ball joint structure of the present invention includes an inner spherical surface provided in the piston and a sphere portion provided in the connecting rod.
The inner spherical surface and the spherical portion were made of an iron-based sintered material in which a sealing treatment was performed with an oxide film.

  Then, the inner spherical surface and the sphere portion were made of an iron-based sintered material that was further nitrided, or the sphere portion was made of an iron-based sintered material that had been sealed and nitrided with an oxide film.

  Moreover, in any of the above-described hermetic compressors, the hardness of the rotation restricting portion is larger than the surface hardness of the spherical portion.

  The connecting rod is Vickers hardness, and the internal hardness is lower than the portion close to the surface.

  In addition, a hydrocarbon refrigerant is used as the refrigerant compressed by the compression element, and an ester synthetic oil is used as the lubricating oil.

  ADVANTAGE OF THE INVENTION According to this invention, the sliding loss of a ball joint part can be reduced and the compressor which improved the efficiency can be provided.

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

  FIG. 1 is a longitudinal sectional view of a hermetic compressor according to an embodiment of the present invention. The hermetic compressor of the present embodiment is a reciprocating compressor in which a piston 4 reciprocates in a cylinder 1 formed integrally with a bearing 1a and a frame 1b provided in a hermetic container to constitute a compression element. It is. At the lower part of the frame 1b, a stator 5 and a roller 6 constituting an electric motor are provided as electric elements, and a crankpin 7a is provided at a position eccentric from the rotation center of the crankshaft 7.

  The crankshaft 7 extends through the bearing portion 1a of the frame and extends from the lower portion to the upper portion of the frame 1b, and the crankpin 7a is provided so as to be positioned above the frame 1b. The lower part of the crankshaft 7 is directly connected to the rotor 6, and the crankshaft 7 is rotated by the power of the electric motor. The crank pin 7 a and the piston 4 are connected by a connecting rod 2, and the piston 4 reciprocates via the crank pin 7 a and the connecting rod 2.

  That is, in the hermetic compressor of this embodiment, a compression element such as a cylinder 1 and a piston 4 and an electric element such as an electric motor are housed in a hermetic container, and the rotational force from the electric element is transmitted by the crankshaft 7. The configuration is assumed. Although the connection structure of the connecting rod 2 and the piston 4 will be described later, the piston 4 opens toward the crankshaft 7 and has an inner spherical surface in the opening.

  Next, the piston 4 will be described with reference to FIGS. FIG. 2 is a detailed view of the inner structure of the piston 4 and is a view of the piston 4 as viewed from the crankshaft 7 side. The piston 4 of the present embodiment opens on the crankshaft 7 side, and has an inner spherical surface 4a on the back side inside the opening. 3 is a cross-sectional view taken along line AA in FIG. 2, and FIG. 4 is a cross-sectional view taken along line BB in FIG.

  2 is a view of the piston 4 as viewed from the crankshaft 7 side as described above. When the piston 4 is attached to the hermetic compressor, the vertical direction of FIG. 2 is the vertical direction of the hermetic compressor in FIG. Match the vertical direction. 2 is a horizontal direction connecting the near side and the far side in FIG. Therefore, FIG. 3 shows a state in which the AA cross section which is a horizontal cross section is viewed from the upper side or the lower side of the piston 4, and FIG. 4 shows the BB cross section which is a vertical cross section of the piston 4. It shows the state seen from the left side or the right side. 3, the lower side in the figure is the back side of the piston 4, and the right side in FIG. 4 is the back side of the piston 4.

  As will be described later, the inner spherical surface 4a of the piston 4 constitutes a bearing structure that receives the outer spherical surface of the spherical portion provided at the tip of the connecting rod 2, and the outer spherical surface of the connecting rod 2 is 180 ° in the AA cross section. The shape is wrapped at the above angle. Accordingly, the outer spherical surface of the connecting rod 2 is held by the inner spherical surface 4a of the piston 4, and the connecting rod 2 and the piston 4 are connected. On the other hand, the BB cross section has a shape that wraps the outer spherical surface of the connecting rod 2 at an angle of 180 ° or less, and the BB cross section has a structure with a smaller sliding area than the AA cross section.

  Thus, since the center angle of the circular arc in the horizontal direction (AA cross section) of the inner spherical surface 4a is formed larger than the center angle of the circular arc in the vertical direction (BB cross section), it slides in the vertical direction. The ball joint structure has a cross-section with a small area. Accordingly, the lubricating oil can easily pass through, and the route through which the lubricating oil passes is shortened, the lubricating oil can easily flow into and out of the connecting portion, and wear due to sliding can be reduced. Moreover, since there is a concave portion on the inner side of the inner spherical surface 4a, the sliding surface can be made smaller.

As apparent from FIGS. 2 to 4, a space exists above and / or below the inner spherical surface 4 a located on the inner side of the inner peripheral portion of the piston 4, and a retaining member is provided in this space. 10 is disposed. The retaining member 10 and its attached state will be described later.

  Next, the connecting rod 2 connected to the piston 4 will be described with reference to FIG. The connecting rod 2 of this embodiment has a structure having a rod part 2c that connects a spherical part 2a connected to the inner spherical surface 4a of the piston 4 as one end and a bearing part connected to the crankshaft 7 as the other end. FIG. 5 is a perspective view of the connecting rod 2 having this structure.

As shown in the figure, the connecting rod 2 includes a spherical body portion 2a inserted into the inner spherical surface 4a of the piston 4, a radial bearing portion 2b inserted into the crankpin 7a, and a rod portion connecting the spherical body portion 2a and the radial bearing portion 2b. 2c, and the outer spherical surface of the sphere part 2a has a structure in which a part of the sphere is cut away.

  The part of the sphere that is partly cut out is a small dimension part that is smaller than the outer diameter dimension of the sphere, and the connecting rod 2 and the piston 4 are connected using this small dimension part. The connection between the two will be described later. In this embodiment, the small dimension portion is formed by plane portions parallel to each other, and the dimension between the two plane portions is smaller than the outer diameter dimension of the sphere (ie, the diameter of the arc) and the dimension of the small dimension portion. Become.

  Thus, since it has the structure which has a plane part on the one side and the other side of the outer spherical surface 2a, even if the piston 4 and the connecting rod 2 are connected, the path through which the lubricating oil passes is short, and the lubricating oil easily flows. It becomes a structure which can supply lubricating oil to a sliding part.

  In connecting the connecting rod 2 and the piston 4, a plane portion provided on the outer spherical surface 2 a of the connecting rod 2 is used. As shown in FIG. 3, the inner spherical surface 4 a of the piston 4 is shaped to wrap the outer spherical surface 2 a of the connecting rod 2 at an angle of 180 ° or more, and the opening dimension L of the inner spherical surface 4 a in the AA cross section is that of the outer spherical surface 2 a. The dimension is smaller than the outer diameter. On the other hand, the dimension between the two flat portions of the outer spherical surface 2a is set smaller than the opening dimension L of the inner spherical surface 4a. The part with the opening dimension L is a gap for inserting the spherical body part of the connecting rod 2, and the above-mentioned small dimension part shows a part smaller than the opening dimension L.

  In this embodiment, the two plane portions provided on the outer spherical surface 2a are provided substantially in parallel, and both plane portions can be inserted into the opening of the inner spherical surface 4a. After the connecting rod 2 is inserted into the inner spherical surface 4a of the piston 4, the connecting rod 2 and the piston 4 are rotated relative to each other so that they are connected. In the present embodiment, the outer spherical surface 2a is provided with two flat portions. However, the present invention is not necessarily limited to this, and the dimension is smaller than the opening dimension L of the inner spherical surface 4a so that the two can be connected. What is necessary is just to provide a part in the outer spherical surface 2a.

  The connecting rod 2 and the piston 4 connected in this way do not come out because the opening size of the inner spherical surface 4a is smaller than the outer diameter of the spherical body portion 2a unless both of them rotate relative to each other. Can be reduced.

  However, if the two are relatively rotated by some action such as impact, the connection between the connecting rod 2 and the piston 4 is released. Therefore, in this embodiment, the retaining member 10 is provided to prevent the disconnection. .

  The retaining member 10 will be described with reference to FIGS. 6 and 7. FIG. 6 is a perspective view of the retaining member 10 according to the present embodiment, and FIG. 7 is a perspective view showing a state of the piston 4 and the connecting rod 2 in which the retaining member 10 is assembled and connected. The retaining member 10 of this embodiment has a shape that also functions as a rotation restricting member that prevents relative rotation between the connecting rod 2 and the piston 4, and is fixed to the piston 4 side, not the connecting rod 2 side. Is one of the features.

  In order to provide the rotation restricting member, a method of fixing to the piston 4 side as in this embodiment and a method of fixing to the connecting rod 2 side are conceivable, but in this embodiment, a method of fixing to the piston 4 side as described above. It was adopted. In the operating state of the hermetic compressor, the rotational movement of the crankshaft 7 is converted into the reciprocating movement of the piston 4 via the connecting rod 2 to compress the refrigerant in the cylinder 1. That is, in the reciprocating compressor, the piston 4 reciprocates, whereas the connecting rod 2 performs a combined movement in the direction perpendicular to the reciprocating direction of the piston 4. Therefore, when the rotation restricting member is provided on the piston 4 side, the fixing is less likely to be released than when the rotation restricting member is provided on the connecting rod 2 side, and the reliability can be improved.

  Further, the relative positional relationship between the piston 4 and the connecting rod 2 always changes during one cycle in which the piston 4 reciprocates. Here, when the rotation restricting member is provided on the connecting rod 2 side, the position of the rotation restricting member is always changed inside the opening of the piston 4, and the sliding surface is likely to increase. Since an increase in the sliding surface can cause abnormal noise, there is a problem that the quality is liable to deteriorate as well as reliability. In the present embodiment, a rotation restricting member is provided on the piston 4 side to solve these problems.

  As shown in FIG. 6, a retaining member (and a rotation restricting member; the same applies hereinafter) 10 of the present embodiment includes a first elastic portion 10a, a second elastic portion 10b, a support portion 10c that connects these elastic portions, and a connecting rod. The rotation restricting portion 10d for restricting the relative rotation of the two is provided. Among these components, the first elastic portion 10a and the second elastic portion 10b are in contact with the inner peripheral portion inside the opening of the piston 4, and the retaining member 10 is supported by the elastic force. The state in which the retaining member 10 is attached to the piston 4 together with the connecting rod 2 will be described later.

  The rotation restricting portion 10d forms walls for restricting the connecting rod 2 and the piston 4 when the connecting rod 2 and the piston 4 are to rotate relatively, and these walls are provided to face each other. In a state in which the connecting rod 2 is attached, the plane portion provided on the spherical body portion 2a of the connecting rod 2 and the respective rotation restricting portions 10d are arranged to face each other. In the present embodiment, since the dimension portion smaller than the opening dimension L of the inner spherical surface 4a provided in the spherical body portion 2a is formed by the flat portion, the rotation restricting portion 10d has a substantially flat portion, and each other Both opposing rotation restricting portions 10d are provided so as to be substantially parallel. The shape of the rotation restricting portion 10d will be described later.

  FIG. 7 is a perspective view showing a state in which the retaining member 10 is attached. When the retaining member 10 is attached, the first elastic portion 10 a generates a force that pushes the inner peripheral portion 4 b of the piston 4, and the retaining member 10 is fixed inside the opening of the piston 4 by a frictional force. Similarly, the second elastic portion is also brought into contact with the inner peripheral portion 4 b, and the retaining member 10 is firmly fixed inside the opening of the piston 4. Thus, both the elastic parts 10a and 10b shall generate | occur | produce force in the direction which pinches | interposes the spherical body part 2a with respect to the rotation control part 10d.

  When the retaining member 10 is fixed in this manner, the piston 4 rotates within the cylinder 1, and even if the connecting rod 2 and the piston 4 try to rotate relative to each other, the connecting rod 2 does not reach the position where it can be removed from the piston 4. There can be no configuration. Because the distance between the rotation restricting portions 10d facing each other is smaller than the outer diameter of the spherical portion 2a, when the connecting rod 2 and the piston 4 try to rotate relatively, the outer spherical surface of the spherical portion 2a becomes the rotation restricting portion 10d. This is because the rotation is restricted by always contacting.

In this embodiment, since the rotation restricting portion 10d forming the wall is fixed by the first elastic portion 10a and the second elastic portion 10b having a spring structure, the rotation restricting portion 10d and the spherical portion 2a of the connecting rod 2 Even if they collide, excessive deformation of both can be prevented. Further, when the retaining member 10 is attached, a ball joint structure can be realized without deforming the inner spherical surface 4a of the piston 4 or the spherical portion 2a of the connecting rod 2.

  Further, since the rotation restricting portion 10d merely forms a wall, it does not slide with the connecting rod 2 in the normal operation state of the compressor. Therefore, it is possible to suppress loss due to friction between the two and generation of abnormal noise.

  Furthermore, since a plurality of spring members constituting the elastic portions 10a and 10b are arranged in the circumferential direction of the inner peripheral surface of the piston, the attachment state of the rotation restricting portion 10d can be stably maintained. In addition, the ease of attaching the retaining member 10 is improved. In addition, since the elastic portions 10a and 10b have curved surfaces along the inner peripheral surface 4b of the piston 4, the rotation restricting portion 10d can be further stably held.

Further, the elastic part 10a and the rotation restricting part 10d located above and the elastic part 10b and the rotation restricting part 10d located below are connected by a support part 10c. These elastic parts 10a and 10b, the rotation restricting part Since the part 10d and the support part 10c are comprised by one member, the maintenance of an attachment state and the improvement of the ease of attachment can be aimed at.

  8A and 8B are views showing a state in which the spherical body portion 2a of the connecting rod 2 is in contact with the rotation restricting portion 10d. FIG. 8A is a front view showing the contact state, and FIG. 8B is a perspective view at the time of contact. It is. When the connecting rod 2 and the piston 4 rotate relatively, the spherical body portion 2a comes into contact with the rotation restricting portion 10d. At this time, the rotation restricting portion 10d serves as a wall to restrict excessive rotation, thereby preventing the piston 4 from coming off the connecting rod 2. Further, since the rotation restricting portion 10d is elastically supported by the elastic portions 10a and 10b, even when the connecting rod 2 and the piston 4 are suddenly rotated, the spherical portion 2a collides with the rotation restricting portion 10d. Reduces the impact and prevents damage.

  As shown in FIG. 8, the rotation restricting portion 10d of this embodiment has a convex shape on the spherical body portion 2 side, and the convex shape portion 10d 'enters the opening on the upper side of the inner spherical surface 4a of the piston 4. It has become. Further, the retaining member 10 is attached so that the lower opening of the inner spherical surface 4a also includes the convex portion as in the upper side. The operation of providing such a rotation restricting portion 10d is as follows.

  If the rotation restricting portion 10d does not have the convex shape portion 10d 'as described above and has a uniform planar shape as a whole, when the relative rotation between the piston 4 and the connecting rod 2 occurs, the rotation restricting portion 10d and the rotation restricting portion 10d first. The abutting portion is a boundary portion 2a 'between the arc portion of the spherical portion 2a and the flat portion. Since this portion corresponds to an arc and a flat ridgeline, there is a case where the rotation restricting portion 10d and the boundary portion 2a ′ may be damaged if they collide with the rotation restricting portion 10d vigorously. Further, if the rotation restricting portion 10d has a simple planar shape, there is a problem that deformation is likely to occur at the time of contact.

  In the present embodiment, these problems are solved by the configuration having the convex portion 10d '. However, merely providing the convex shape portion 10d ′ contributes to improving the strength of the rotation restricting portion 10d, but the boundary portion 2a ′ first collides with the rotation restricting portion 10d depending on the shape and height. Therefore, the convex portion 10d ′ of the present embodiment is first brought into contact with the flat portion of the spherical body portion 2a when the piston 4 and the connecting rod 2 are rotated relative to each other. As a specific configuration, the width of the flat portion of the connecting rod sphere 2a facing the convex portion 10d 'is set to be larger than the width of the upper end portion of the convex portion 10d'.

  As described above, since the rotation restricting portion 10d can be brought into contact with the flat portion which is the small size portion of the spherical body portion 2a, only the strength of the rotation restricting portion 10d and eventually the retaining member 10 can be improved. Instead, damage to the connecting rod 2 due to collision or the like can also be reduced.

  As shown in FIG. 8, the convex portion 10d 'does not close the space between the spherical body portion 2a and the retaining member 10, but a space is provided between the two so that the lubricating oil flows in and out. To secure a gap for.

  In this structure, the first elastic portion 10a and the second elastic portion 10b are connected by the support portion 10c, and the distance between the rotation restricting portions 10d and 10d is maintained. Although the support part 10c has connected the near side of both rotation control parts mutually, a problem may arise when it collides with the spherical body part 2a by the side of the connecting rod 2. FIG. That is, when the rotational force in the axial direction of the piston 4 acts excessively, the spherical body portion 2a of the connecting rod 2 and the rotation restricting portion 10d come into contact with each other and collide with each other, the elastic portion 10a or 10b is pushed in, and both rotation restricting portions 10d A phenomenon that the back side opens may occur.

  At this time, since the relationship between the retaining member 10 and the connecting rod 2 as described above cannot be maintained, the retaining member 10 is easily detached from the piston 4. Therefore, the retaining member 10 is fixed inside the piston 4 with the following configuration.

  FIG. 9 is a cross-sectional view of a connecting portion between the connecting rod 2 and the piston 4, and this cross section corresponds to the AA cross section of FIG. 2 in a state where both are connected. The shape of the retaining member 10 and the shape of the piston 4 will be described with reference to FIG. The retaining member 10 in this example includes an extending portion 10e extending from the support portion 10c to the inner peripheral surface side of the piston 4. The end portion of the extending portion 10e is formed by being bent toward the opening side of the piston 4, and the bending direction may be opposite to the elastic portions 10a and 10b. That is, the end of the extending portion 10e is bent toward the opening side of the piston 4 with respect to the elastic portions 10a and 10b located on the back side in the piston 4 from the support portion 10c. The bent shape is not particularly limited as long as it satisfies the above conditions and is inserted into the groove 4c provided on the inner peripheral surface of the piston 4 at the end of the extending portion 10e.

  In addition, when the end portion of the extending portion 10e is inserted into the groove 4c, the distal end portion of the extending portion 10e is in contact with the stepped portion of the groove 4c. From the relationship of the direction in which 10 is pulled out, the distal end portion of the extending portion 10e serves as a support and can be prevented from falling off the piston 4. On the other hand, when attaching the retaining member 10, if the end of the extending portion 10 e is pushed to the position of the groove 4 c, both can be easily engaged and the attachment property can be improved. Therefore, even when a force is applied in the direction in which the retaining member 10 is detached from the piston 4, this can be suppressed and the connection between the piston 4 and the connecting rod 2 can be prevented from being disconnected.

  FIG. 10 is a perspective view of the retaining member 10 in which the extending portion 10e is provided on the support portion 10c. As shown in the drawing, the extending portion 10e is provided at a position exactly in the middle of both rotation restricting portions 10d. The extending portion 10e also has an elastic force like the elastic portions 10a and 10b. When the retaining member 10 is attached, the extending portion 10e is in a state of being pushed into the opening of the piston 4 with respect to the inner peripheral surface of the piston 4. Give elastic force. When the extending portion 10e is bent and pushed to the position of the groove 4c, the distal end portion of the extending portion 10e is inserted into the groove 4c.

  When the distal end of the extending portion 10e is inserted into the groove 4c and the retaining member 10 is attached to the piston 4, it is not necessary for the extending portion 10e to give elastic force to the inner peripheral surface of the piston 4 in the groove 4c. . However, in this embodiment, even when the retaining member 10 is attached, it is attached so as to apply an elastic force to the inner peripheral surface of the piston 4. By attaching the retaining member 10 in this way, it is possible to effectively prevent the retaining member 10 from falling off the piston 4.

  In the above-described example, the extending portion 10e is provided in the support portion 10c, and the end portion of the extending portion 10e is engaged with the groove 4c, but FIG. 11 shows the inner peripheral surface of the piston 4 on the elastic portions 10a and 10b. The example provided with the extending | stretching part 10e extended | stretched to the side is shown. FIG. 10 is a longitudinal sectional view of a connecting portion between the connecting rod 2 and the piston 4 in this example, and this section corresponds to the BB section in FIG. 2 in a state where both are connected.

  In these examples, since the end portion of the extending portion 10e is inserted into the groove 4c, the extending portion 10e and the groove 4c are engaged even when a force acts in the direction in which the retaining member 10 is removed from the piston 4. In combination, the end portion of the extending portion 10e serves as a support, and the retaining member 10 can be prevented from falling off the piston 4. Therefore, the connecting state of the connecting rod 2 and the piston 4 is maintained, and it can be set as the structure which contributes to ensuring reliability.

  Moreover, in the example of FIG. 11, since the extending | stretching part 10e is provided in the elastic parts 10a and 10b, there exist the following effects. In this example, the first elastic portion 10a and the second elastic portion 10b are arranged at positions facing each other with the spherical body portion 2a of the connecting rod 2 and the rotation restricting portion 10d interposed therebetween. The spherical body 2a, the rotation restricting portion 10d, the first elastic portion 10a (or the second elastic portion 10b), the extending portion 10e, and the groove 4c are located in this order. Therefore, even if the spherical portion 2a collides with the rotation restricting portion 10d, the force in the direction in which the extension portion 10e and the groove 4c are disengaged is unlikely to work, and the retaining member 10 can be prevented from falling off.

Hereinafter, the result of having examined the effect of these structures is mentioned, showing the further example of these Examples. Here, a case where the radius of the spherical body portion 2a of the ball joint structure is 6.495 mm and the radius of the inner spherical surface 4a is 6.505 mm will be described as an example. In the ball joint structure, it goes without saying that the diameter of the spherical portion 2a is smaller than the diameter of the inner spherical surface 4a on the piston 4 side, and the lubricating oil flows in and out of the gap portion caused by the difference in diameter, Lubrication between both members is performed. Moreover, since the center position of both does not always exist in the same position, the recessed part is especially provided in the innermost part of the inside of piston 4 (refer FIG. 9, FIG. 11, etc.). This concave portion also functions as an oil reservoir for lubricating oil. For example, as shown in FIGS. 9 and 11, a lubricating oil supply hole may be provided inside the connecting rod 2 to communicate with the concave portion.

Further, as the angle of the inner spherical surface 4a in the cross section shown in FIG. 3, the angle θ41 from the axis of the piston 4 was 97 °, and the angle θ42 shown in FIG. 4 was 34 °. By defining θ41 and θ42 in this way, the route through which the lubricating oil passes in the BB cross section is shortened by about し て compared to the AA cross section, and the inner spherical surface 4a is set to 97 ° over the entire surface. Compared to the case, the amount of lubricating oil flowing through the ball joint structure was increased about three times.

  Further, the groove 4c provided on the inner peripheral surface of the piston 4 is a rectangle having a width of 1 mm and a depth of 1 mm, and is provided uniformly in a ring shape on the inner periphery of the piston 4.

  When the ball joint structure having such a specific structure was used for a hermetic compressor, the ball joint structure was not detached, and good slidability could be maintained. This result is the same for the retaining member as shown in FIGS. 9 and 10 and the retaining member as shown in FIG. 11. It was confirmed that it contributed to the improvement of the property.

  As described above, according to each embodiment of the present invention, assembly can be easily performed without deforming the inner spherical surface and the outer spherical surface of the ball joint structure. In addition, the sliding area is reduced by notching part of the inner sphere side and the outer sphere side of the ball joint mechanism portion, and the lubricating oil can be easily moved.

  Accordingly, it is possible to reduce the sliding loss during operation of the hermetic compressor and contribute to the improvement of the efficiency, and to suppress the noise and the like due to the occurrence of abnormal noise.

  Moreover, since the connection release of the ball joint structure can be suppressed, a hermetic compressor having high reliability can be provided.

  Next, the materials of the piston 4 and the connecting rod 2 constituting the ball joint mechanism will be described. In this embodiment, the spherical portion 2a serving as the sliding portion of the ball joint and the inner spherical surface 4a of the piston 4 are made of an iron-based sintered material sealed with an oxide film. Specifically, after sintering the raw material powder, the shape is appropriately processed, and steam treatment is performed to seal internal and surface vacancies with an oxide film generated on the vacancy surface, and the lubricating oil film passes through the vacancies. It is designed not to be easily discharged. As will be described later, the oxide in the sealing portion by the water vapor treatment also has an effect of improving the strength of the sintered material.

  FIG. 12 shows the results of a sliding test performed on a material used for the piston 4 and the connecting rod 2 using a ring-on-block friction tester. In this test, the sliding speed was 1.01 m / s and the test load was 123.5 N. In the sliding test, the sintered material 1 and the sintered material 2 are used, and these sintered materials have different carbon contents (see the * column in FIG. 12). The combination of the rotating piece and the fixed piece includes those subjected to an oxide film treatment with water vapor and those subjected to nitriding treatment, and each combination of No. 1 to No. 5 as a combination of the rotating piece and the fixed piece. The amount of wear was measured.

  From the test results shown in the figure, it can be seen that in No. 1 and No. 2 in which only the fixed piece is subjected to the oxide film treatment, the rotating piece has a large amount of wear. On the other hand, No.3, No.4, and No.5 using a sintered material in which both the rotating piece and the fixed piece were subjected to the oxide film treatment resulted in a small amount of wear. From this result, it can be said that the amount of wear can be reduced by using a sintered material sealed with water vapor for the piston 4 and the connecting rod 2.

  FIG. 13 shows the results of measuring the apparent hardness of the Rockwell B scale of the sintered material. In comparison with the combination of materials with a small amount of wear in FIG. 12, it can be seen that the hardness of the rotating piece is equivalent or about 10 higher on the Rockwell B scale than the hardness of the fixed piece. According to such a combination, it is possible to reduce the amount of wear of the connecting rod 2 that is likely to cause problems due to wear.

  Based on the results of FIG. 12 and FIG. 13, a material obtained by performing an oxide film treatment on the sintered material is used as the material of the piston 4 and the connecting rod 2.

  As a more specific example, an Fe-Cu-C-based sintered material that has been subjected to an oxide film treatment is used as the material of the piston 4, and an Fe-Cu-C-based material that has been subjected to an oxide film treatment as the material of the connecting rod 2 Using a sintered material, a hermetic compressor as shown in FIG. 1 was manufactured using these piston 4 and connecting rod 2. When the hermetic compressor was operated at 4900 rpm for 30 days at a discharge pressure of 1.6 MPa, abnormal wear did not occur in the ball joint structure, and good slidability could be maintained. It was.

  As a second example, an Fe-Cu-C sintered material subjected to an oxide film treatment is used as the material of the piston 4, and an Fe-Cu-C system subjected to an oxide film treatment and a nitriding treatment as the material of the connecting rod 2 A hermetic compressor using sintered material was manufactured and operated for 30 days at an operating speed of 4900 rpm and a discharge pressure of 1.6 MPa. Abnormal wear did not occur in the ball joint structure, and good sliding performance was achieved. The result which can maintain mobility was obtained.

  As a third example, Fe-Cu-C sintered material subjected to oxide film treatment and nitriding treatment is used as the material of the piston 4, and Fe-Cu subjected to oxide film treatment and nitriding treatment as the material of the connecting rod 2 is used. -A sealed compressor using a C-based sintered material was manufactured and operated at 4900 rpm for 30 days at a discharge pressure of 1.6 MPa. Even in this case, abnormal wear was observed in the ball joint structure. It did not occur, and good slidability was maintained.

  Consider these three examples below. FIG. 14 shows measurement results showing the relationship between the depth and hardness of the piston material and connecting rod material. As shown in the figure, the relationship between the depth of the material and the hardness is shown with the depth from the surface of each material as the horizontal axis and the Vickers hardness HV as the vertical axis. As an example of the sintered material 1 (A), nitriding treatment was further applied to a material in which internal and surface vacancies were sealed by an oxide film generated on the vacancy surface by performing steam treatment after sintering. Something is used. (B) shows an example in which nitriding treatment is performed without performing an oxide film treatment, and (C) example shows an example in which an oxide film treatment is performed and no nitriding treatment is performed.

  In addition, the (α) example of the sintered material 2 is obtained by performing an oxide film treatment and a nitriding treatment, and the (β) example shows an example in which the oxide film treatment is performed and the nitriding treatment is not performed. These nitriding treatments were performed by general gas soft nitriding at a nitriding treatment temperature of about 500 to 600 ° C.

  As can be seen from FIG. 14, the hardness is improved by further nitriding the oxide film produced by the water vapor treatment. Therefore, it is desirable to use a sintered material that is sealed with water vapor and further nitrided for the connecting rod 2. At this time, a sintered material subjected to nitriding treatment may be used for the piston 4 (the above third example), but the piston 4 is nitrided to avoid the surfaces of the same material type. It is not necessary to perform a process (the above second example).

  On the other hand, when the nitriding treatment is performed without performing the sealing treatment with water vapor, as shown in FIG. 14, the inside is cured through the micropores in the sintered material, and the whole material becomes brittle. Therefore, the reliability is likely to be lowered due to the breakage of the connecting rod 2 or the like.

  In this example, the portion close to the surface retains sufficient hardness to ensure wear resistance, but the internal hardness is lower than the portion close to the surface by Vickers hardness, and the connecting rod has excellent toughness. 2 is obtained. Therefore, the nitriding treatment is performed after the sealing treatment is performed by the steam treatment, and this makes it possible to provide a hermetic compressor having excellent reliability.

  Note that the same effect can be expected when carburizing or nitronitriding is performed instead of the above nitriding.

  In order to perform the surface treatment as described above, the following dimensional considerations are necessary in manufacturing. That is, when manufacturing the connecting rod 2, the shape is first processed appropriately after the raw material powder is sintered. At this time, it is necessary to make the diameter of the part which becomes the spherical body part 2a of the connecting rod 2 smaller than the diameter of the inner spherical surface 4a of the piston 4 at the time of completion. On the other hand, the diameter of the portion that becomes the inner spherical surface 4a of the piston 4 needs to be larger than the diameter of the spherical portion 2a of the connecting rod 2 at the time of completion. Thereafter, steam treatment or the like is performed, and the diameter of the spherical portion 2a is increased by that amount, and the diameter of the inner spherical surface 4a is decreased.

  Next, the retaining member 10 will be described. The connecting rod 2 can be further improved in reliability by making the surface hardness smaller than that of the retaining member 10. As shown in FIG. 8, the portion of the connecting rod 2 where the spherical portion 2a abuts against the retaining member 10 is a flat portion provided on the spherical portion 2a, and this flat portion is the surface of the piston 4 in a normal operation state. It is not a portion that slides with the inner spherical surface 4a. Accordingly, even if the flat portion is worn by a slight amount, there is no significant change in the sliding relationship with the piston 4.

  On the other hand, when the retaining member 10 is worn by contact with the spherical portion 2a and the thickness of the rotation restricting portion 10d is reduced, the retaining member 10 is damaged and the connection between the piston 4 and the connecting rod 2 is released. There is a case. At this time, the function as the hermetic compressor is impaired, causing failure. In the present embodiment, the retaining member 10 uses SUS301-1 / 4H having a hardness higher than the surface hardness of the connecting rod 2 to improve the reliability.

  When the hermetic compressor of the present embodiment described above is actually operated, care must be taken so that the temperature of the sliding portion does not become too high. This is because an excessive increase in the temperature of the sliding part leads to accelerated wear, resulting in a decrease in reliability. In particular, in the case of the present embodiment using the sintered material subjected to the surface treatment, the temperature of the sliding portion during operation is set to 150 ° C. or less in order to prevent a decrease in reliability due to an excessive increase in temperature. When the same kind of test as in the first to third examples was performed and the operation was performed, when the temperature of the sliding portion was set to 150 ° C. or lower, abnormal wear did not occur in the ball joint structure, and good sliding was achieved. The result which can maintain mobility was obtained.

  Further, the lubricating oil used in actual operation will be described. In order to retain the oil film on the surfaces of the piston 4 and the connecting rod 2 using a sintered material subjected to sealing treatment (oxide film treatment) or nitriding treatment with water vapor as in the above embodiment, as a lubricating oil, It is effective to use an ester-based synthetic oil having a good adsorption power on the surface of the nitride film. Sealing treatment is indispensable for retaining the oil film of the lubricating oil supplied to the sliding part, and using ester-based synthetic oil that is compatible with the nitride film not only reduces sliding loss but also causes abnormal wear. Can be suppressed.

  As an example, if hydrocarbon-based R600a (isobutane) is used as the refrigerant and ester-based synthetic oil is used as the lubricant, abnormal wear does not occur in the ball joint structure, and good slidability can be maintained. Obtained. In addition, even if mineral oil and ester synthetic oil were mixed and used as the lubricating oil, good slidability was maintained, and high reliability could be obtained as compared with the case where only the mineral oil was used as the lubricating oil.

  According to the above-described embodiment, the abnormal wear occurring on the inner spherical surface and the outer spherical surface of the ball joint structure can be suppressed, so that the long-term reliability of the hermetic compressor is ensured. In addition, the sliding loss during the operation of the hermetic compressor is reduced, and as a result, the efficiency of the hermetic compressor is improved. Therefore, it is possible to provide a hermetic compressor with high reliability and suitable for power saving.

1 is a longitudinal sectional view of a hermetic compressor according to an embodiment of the present invention. Detailed view of the inner structure of the piston. AA sectional drawing of FIG. BB sectional drawing of FIG. The perspective view of a connecting rod. The perspective view of a retaining member. The perspective view which shows the assembly state of a piston and a connecting rod. The figure which showed the state which the spherical body part of the connecting rod contacted the rotation control part. The cross-sectional view of the connection part of a connecting rod and a piston. The perspective view of the retaining member which provided the extending | stretching part in the support part. The longitudinal cross-sectional view of the connection part of a connecting rod and a piston. Wear test results of piston material and connecting rod material. Hardness measurement result of piston material and connecting rod material. Measurement results showing the relationship between the depth and hardness of the piston material and connecting rod material.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cylinder, 2 ... Connecting rod, 2a ... Sphere part, 2a '... Boundary part, 4 ... Piston, 4a ... Inner spherical surface of piston, 4c ... Groove, 7 ... Crankshaft, 10 ... Stopping, 10a ... 1st elastic part DESCRIPTION OF SYMBOLS 10b ... 2nd elastic part, 10c ... Support part, 10d ... Rotation restricting part, 10d '... Convex-shaped part, 10e ... Extending part.

Claims (16)

In a hermetic compressor in which a compression element and an electric element are housed in a hermetic container, and a crankshaft and a piston driven by the electric element are connected by a ball joint structure by a connecting rod.
The ball joint structure includes an inner spherical surface provided in the piston, a spherical portion provided in the connecting rod, and a rotation restricting portion which is a separate member from the piston and the connecting rod, and the rotation restricting portion is attached to the piston. A hermetic compressor that restricts relative rotation with the connecting rod. A compression element and an electric element are housed in an airtight container, a crankshaft that transmits the rotational force from the electric element, a piston that opens to the crankshaft side and has an inner spherical surface, and is connected to the inner spherical surface And a connecting rod having a rod portion that connects both ends of the bearing portion connected to the crankshaft, and the inner spherical surface has a horizontal arc whose central angle is a vertical arc. The spherical portion has a small size portion that is smaller than the horizontal opening size of the inner spherical surface, and the inner spherical surface and the spherical portion are connected by a ball joint structure. A hermetic compressor,
A rotation restricting portion for restricting relative rotation between the connecting rod and the piston at a position facing the small dimension portion;
The rotation restricting portion is attached to the piston, and is capable of contacting the small dimension portion during the relative rotation.   3. The hermetic compressor according to claim 2, wherein the small dimension part is formed by plane parts parallel to each other, and the dimension between the plane parts has the same dimension as the part having a dimension smaller than the diameter of the arc. And the said rotation control part was made into the convex shape which has the planar shape part which opposes the said planar part, The hermetic compressor characterized by the above-mentioned.   4. The hermetic compressor according to claim 2, wherein an elastic portion is provided between the rotation restricting portion and an inner peripheral surface in the opening of the piston, and the rotation restricting portion is caused by an elastic force from the elastic portion. A hermetic compressor characterized by being held.   5. The hermetic compressor according to claim 4, wherein the elastic portion and the rotation restricting portion are provided as a part of a retaining member configured by one member, and the retaining member is an opening of the piston. A hermetic compressor having an extending portion extending toward an inner peripheral surface, and being held by an end portion of the extending portion entering a groove provided on the inner peripheral surface.   6. The hermetic compressor according to claim 4, wherein the elastic portion is a spring member having a curved outer peripheral surface in contact with an inner peripheral surface of the piston and a shape along the inner peripheral surface. A hermetic compressor.   6. The hermetic compressor according to claim 5, wherein the elastic portion and the rotation restricting portion are disposed on both upper and lower sides of the connecting rod, and a dimension between the upper rotation restricting portion and the lower rotation restricting portion. Is larger than the small dimension part, and the elastic part generates a force in a direction of sandwiching the spherical part with respect to the rotation restricting part.   8. The hermetic compressor according to claim 6, wherein the spring member includes a plurality of springs arranged in a circumferential direction of the inner circumferential surface of the piston.   8. The hermetic compressor according to claim 7, further comprising: a support portion connecting between the elastic portion and the rotation restricting portion located above and the elastic portion and the rotation restricting portion located below, and the elastic portion and the rotation restricting portion. A hermetic compressor in which the part and the support part are made of one member.   The hermetic compressor according to claim 9, wherein the extending portion is provided in the support portion. In a hermetic compressor in which a compression element and an electric element are housed in a hermetic container, and a crankshaft and a piston driven by the electric element are connected by a ball joint structure by a connecting rod.
The ball joint structure is composed of an inner spherical surface provided on the piston and a spherical body portion provided on the connecting rod,
A hermetic compressor characterized in that the inner spherical surface and the spherical body portion are an iron-based sintered material whose pores are sealed with an oxide film.   The hermetic compressor according to claim 11, wherein the spherical portion is an iron-based sintered material that has been subjected to sealing treatment and nitriding treatment with an oxide film.   The hermetic compressor according to claim 12, wherein the inner spherical surface is an iron-based sintered material that is further nitrided. An iron-based sintered material sealed with an oxide film is used for the inner spherical surface, and an iron-based sintered material subjected to sealing treatment and nitriding treatment with an oxide film is used for the sphere,
The hermetic compressor according to any one of claims 1 to 10, wherein a hardness of the rotation restricting portion is larger than a surface hardness of the spherical portion.   The hermetic compressor according to any one of claims 11 to 14, wherein the connecting rod has a Vickers hardness and an inner hardness is lower than a portion close to the surface. 15. The hermetic compressor according to claim 11, wherein a hydrocarbon-based refrigerant is used as the refrigerant compressed by the compression element, and an ester-based synthetic oil is used as the lubricating oil.

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