CN100478567C - Sealed type compressor - Google Patents

Abstract

The invention provides a compressor increased in efficiency by reducing sliding loss. 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.

Description

hermetic compressor

technical field

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

Background technique

In a hermetic compressor having a reciprocating piston, a structure is used in which a crankshaft and a piston are connected by a connecting rod, and the motion of a rotary shaft in rotary motion is converted into reciprocating motion. Among them, as a connection structure between a piston and a connecting rod, a structure connected by a radial bearing as described in Patent Document 1 is known.

In the structure of patent document 1, a piston pin is used for the connection part of a piston and a connecting rod, and the bearing structure which forms this piston pin as a shaft connects both.

In addition, as another connecting structure of the piston and the connecting rod, there is known a so-called ball joint (ball joint) structure connected by a spherical bearing as in Patent Document 2 and Patent Document 3. As a structure for connecting by forming a ball joint structure, there is known a structure formed by plastically working an inner spherical surface provided on a piston, as disclosed in Patent Document 2. Also, 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 cut off together, the outer spherical part of the connecting rod is inserted into the inner spherical part of the piston, and the piston is rotated to connect the connecting rod and the piston.

In addition, in Patent Document 2, both or one of nitriding treatment and manganese phosphate coating treatment are performed on the spherical surface receiver of the ball joint structure, and high-carbon chromium steel is used for the spherical surface. Patent Document 4 shows an example of sinter-molding pistons connected by a ball joint.

[Patent Document 1] Japanese Unexamined Patent Publication No. 2004-27969

[Patent Document 2] Japanese Patent Laid-Open No. 2003-214343

[Patent Document 3] Japanese Unexamined Patent Publication No. 2003-184751

[Patent Document 4] Japanese Patent Application Laid-Open No. 64-69862

In the above-mentioned conventional example, in Patent Document 1, the piston and the connecting rod are connected by a piston pin, but this connection structure uses the piston pin inserted on the piston side as a shaft portion, and has a bearing portion on the connecting rod side. Therefore, if the shaft on the piston side is inserted toward the bearing on the connecting rod side, a problem related to sliding may arise. That is, the sliding portion between the piston pin and the connecting rod becomes localized, and at this time, the contact surface pressure between the two also becomes too large, which may also cause a decrease in reliability due to wear of the sliding portion or the like. In Patent Document 1, the supply of lubricating oil is stabilized to improve the reliability, but the localization itself of the sliding part due to the bearing structure is not solved.

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 system. According to the connection of the ball joint method, there is no problem of sliding and abrasion between the piston pin and the connecting rod as in Patent Document 1.

In the structure of Patent Document 2, since the ball seat provided on the piston is molded by plastic working, the above-mentioned problems do not occur, but the sliding between the piston and the connecting rod may cause problems. That is, in order to ensure the connected state, the ball seat part is processed in the direction of closing, so the passage for supplying the lubricating oil to the connecting part becomes narrow, and the lubricating oil may not flow sufficiently. Therefore, the flow of lubricating oil into and out of the connecting portion cannot be ensured sufficiently, which may cause temperature rise and damage of the spherical bearing portion.

On the other hand, the structure in Patent Document 3 has a planar portion in which a part of the spherical portion of the connecting rod is cut away, and after inserting the spherical portion of the connecting rod into the ball seat on the piston side, the spherical portion is rotated. Link the two. This structure can secure a space for supplying lubricating oil, but if the spherical portion and the piston rotate relatively, there will be a problem of disconnection of the connection. Therefore, in Patent Document 3, there is a rotation restricting member to prevent the release of the connection. However, in the rotation restricting member having the structure shown in FIG. possibility. 13 and 15, since the brake is only held by the frictional force, the frictional force changes when the force of the piston rotation acts during operation, and there is a possibility that the brake of the connecting rod will come off.

Also, as in Patent Document 2, when a high-carbon chromium steel material is used for the spherical surface (ball), since the hardness of the high-carbon chromium steel material is high, a problem arises in workability. That is, materials that are not only high in wear resistance but also excellent in workability are sought. In addition, when such a material with high hardness is used, in Patent Document 2, it is difficult to integrally mold the connecting rod due to the problem of workability. Therefore, in order to make the shape of the spherical surface to be connected with the piston close to a perfect circle, it is necessary to separately form the rod portion and the spherical portion and then connect them. At this time, there is a case where the production efficiency is lowered.

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. Therefore, not only loss is likely to occur on the sliding surface of the piston, but also the reliability caused by the progress of wear may be caused. decrease.

Contents of the invention

The present invention is made to solve the problems caused by the above-mentioned conventional examples, and its object is to provide a hermetic compressor of a ball joint type in which a piston and a rod are connected by a spherical bearing to ensure reliability or reduce sliding loss. Compressor for increased efficiency.

In order to achieve the above object, the hermetic compressor of the present invention accommodates the compression mechanism and the motor in an airtight container, and uses a connecting rod to connect the crankshaft and the piston driven by the motor through a ball joint structure. In said hermetic compressor,

The ball joint structure of the present invention is composed of an inner spherical surface provided on the piston, a spherical part provided on the connecting rod, and a rotation restricting part which is a member different from the piston and the connecting rod. relative rotation of the connecting rods.

In addition, in order to achieve the above object, the hermetic compressor of the present invention accommodates a compression mechanism and a motor in an airtight container, and the hermetic compressor has: a crankshaft that transmits rotational force from the motor; a piston that is on the side of the crankshaft open and has an inner spherical surface in the opening; and a connecting rod, one end of which is a spherical body connected to the inner spherical surface, the other end is a bearing portion connected to the crankshaft, and has a rod connecting the two ends, the inner spherical surface The center angle of the circular arc in the horizontal direction is larger than the central angle of the circular arc in the vertical direction, the spherical part has a small-sized part having a size smaller than the opening size in the horizontal direction of the inner spherical surface, and the inner spherical surface and the The spherical parts are connected by a ball joint structure, and in the hermetic compressor,

There are two rotation restricting parts at a position facing the small size part, and the two rotation restricting parts restrict relative rotation between the connecting rod and the piston,

The rotation restricting portion is mounted on the piston, and during the relative rotation, can come into contact with the small-sized portion of the spherical portion, and the small-sized portion is formed by flat portions parallel to each other, so that the flat surface The dimension between the portions has: the same dimension as the portion having a dimension smaller than the diameter of the arc, the two rotation restricting portions are formed in a convex shape having a planar shape facing the planar portion, in In a state where the link is mounted, the flat surface portion provided on the spherical portion of the link is arranged to face the two rotation restricting portions.

In addition, in the hermetic compressor described above, the small-sized portion is formed by mutually parallel planar portions such that a dimension between the planar portions has the same dimension as that of a portion having a dimension smaller than the diameter of the arc, The rotation restricting portion is formed in a convex shape having a planar shape facing the planar portion.

In addition, 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.

In addition, these elastic portions and rotation restricting portions are provided as part of a single-member anti-seismic member having an extension portion extending toward the inner peripheral surface inside the opening of the piston, and the end portion of the extension portion is inserted into the It is held in the groove provided on the inner peripheral surface of the piston.

In addition, the outer peripheral surface of the elastic portion in contact with the inner peripheral surface of the piston is curved, and the elastic portion is a spring member having a shape along the inner peripheral surface of the piston.

In addition, the elastic portion and the rotation restricting portion are arranged on both sides of the upper and lower sides of the connecting rod, the dimension between the upper rotation restricting portion and the lower rotation restricting portion is larger than the small size portion, and the elastic portion is These rotation restricting portions generate a force in a direction to clamp the spherical portion.

In addition, there are a plurality of spring members constituting the elastic portion, and the spring members are constituted by springs arranged in the circumferential direction on the inner peripheral surface of the piston.

In addition, the upper elastic portion and the rotation restricting portion are connected to the lower elastic portion and the rotation restricting portion by the support portion, and these elastic portions, the rotation restricting portion, and the support portion are constituted by a single member.

In addition, the extension part of the anti-dropping member is provided on the support part.

In addition, in order to achieve the above object, the ball joint structure of the present invention is composed of an inner spherical surface provided on the piston and a spherical part provided on the connecting rod,

The inner spherical surface and the spherical portion are formed of an iron-based sintered material that has been sealed with an oxide film.

Furthermore, the inner spherical surface and the spherical portion are formed of an iron-based sintered material further subjected to a nitriding treatment, or the spherical portion is formed of an iron-based sintered material subjected to a sealing treatment and a nitriding treatment with an oxide film.

In addition, in any one of the hermetic compressors described above, the rotation restricting portion has a hardness greater than a surface hardness of the spherical portion.

In addition, the connecting rod is calculated by Vickers hardness, and the inner hardness is lower than the hardness of the part close to the surface.

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

According to the present invention, it is possible to provide a compressor in which the sliding loss of the ball joint portion can be reduced and the efficiency can be improved.

Description of drawings

Fig. 1 is a longitudinal sectional view of a hermetic compressor according to an embodiment of the present invention;

Fig. 2 is a detailed view of the inner structure of the piston;

Fig. 3 is the A-A sectional view of Fig. 2;

Fig. 4 is the B-B sectional view of Fig. 2;

Figure 5 is a perspective view of the connecting rod;

Fig. 6 is a perspective view of the anti-off component;

Fig. 7 is a perspective view showing an assembled state of a piston and a connecting rod;

Fig. 8 is a diagram showing a state in which the spherical portion of the link is in contact with the rotation restricting portion;

Fig. 9 is a cross-sectional view of the linking part of the connecting rod and the piston;

Fig. 10 is a perspective view of an anti-off part provided with an extension part at the supporting part;

Fig. 11 is a longitudinal sectional view of the linking part of the connecting rod and the piston;

Fig. 12 is the wear test result of piston material and connecting rod material;

Fig. 13 is the hardness measurement result of piston material and connecting rod material;

Fig. 14 is a measurement result showing the relationship between the depth and the hardness of the piston material and the connecting rod material.

In the figure,

1-cylinder; 2-connecting rod; 2a-ball part; 2a'-interface; 4-piston; 4a-piston inner spherical surface; 4c-groove; 7-crankshaft; 10b-second elastic part; 10c-support part; 10d-rotation restricting part; 10d'-convex part; 10e-extension part.

Detailed ways

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 this embodiment is a reciprocating compressor. The piston 4 reciprocates in the cylinder 1 to form a compression mechanism. The cylinder 1 is integrally formed by the bearing part 1a and the frame 1b disposed in the airtight container. The lower part of the frame 1b is provided with a stator 5 and a rotor 6 constituting a motor as a motor, and a crank pin 7a is provided at a position eccentric from the rotation center of the crankshaft 7 .

The crankshaft 7 extends upward from the lower portion of the frame 1b through the bearing portion 1a of the frame, and the crank pin 7a is provided on the upper side of 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 the connecting rod 2 , and the piston 4 reciprocates via the crank pin 7 a and the connecting rod 2 .

That is, the hermetic compressor of this embodiment presupposes a structure in which a compression mechanism such as cylinder 1 and piston 4 and electric parts such as an electric motor are accommodated in an airtight container, and rotational force from the electric motor is transmitted through crankshaft 7 . The connection structure between the connecting rod 2 and the piston 4 will be described later. The piston 4 is opened on the side of the crankshaft 7 and has an inner spherical surface in the opening.

The piston 4 will be described below with reference to FIGS. 2 to 4 . FIG. 2 is a detailed view of the inner structure of the piston 4, and is a view of the piston 4 viewed from the crankshaft 7 side. The piston 4 of this embodiment is open on the side of the crankshaft 7, and has an inner spherical surface 4a on the inner side of the opening. FIG. 3 is a sectional view along A-A of FIG. 2 , and FIG. 4 is a sectional view along B-B of FIG. 2 .

As mentioned above, FIG. 2 is a view of the piston 4 viewed from the crankshaft 7 side. When the piston 4 is attached to the hermetic compressor, the vertical direction in FIG. 2 coincides with that of the hermetic compressor in FIG. 1 . In addition, the left-right direction in FIG. 2 is a horizontal direction connecting the front side and the back side in FIG. 1 . Therefore, FIG. 3 is a diagram showing a state in which a section on a horizontal plane, that is, an A-A section is viewed from the upper side or a lower side of the piston 4, and FIG. state diagram. In addition, in FIG. 3 , the lower side in the figure is the inner side of the piston 4 , and in FIG. 4 , the right side in the figure is the inner side of the piston 4 .

The inner spherical surface 4a of the piston 4, as will be described later, constitutes a bearing structure for accommodating the outer spherical surface of the spherical body provided at the front end of the connecting rod 2, and is formed at an angle of 180° or greater in the A-A section. The shape of the outer spherical surface surrounding the connecting rod 2. Therefore, the outer spherical surface of the connecting rod 2 is surrounded and held by the inner spherical surface 4 a of the piston 4 , and the connecting rod 2 and the piston 4 are connected. On the other hand, in the cross section B-B, the outer spherical surface of the connecting rod 2 is surrounded by an angle of 180° or less, so that the sliding area in the cross section B-B is smaller than that in the cross section A-A.

Then, since the central angle of the circular arc in the horizontal direction (A-A cross section) of the inner spherical surface 4a is formed to be larger than the central angle of the circular arc in the vertical direction (B-B cross section), a sliding area is formed in the vertical direction. Small cross section ball joint structure. Therefore, the lubricating oil is easily circulated, and the lubricating oil circulation path itself is also shortened, and the lubricating oil flows into and out of the connecting portion easily, thereby reducing wear and the like due to sliding. In addition, since the concave portion exists on the inner side of the inner spherical surface 4a, the sliding surface can be further reduced.

In addition, as is clear from FIGS. 2 to 4 , there is a space above or/and below the inner spherical surface 4 a located on the back side of the inner peripheral portion of the piston 4 , and the anti-slip member 10 is arranged in this space. The detachment preventing member 10 and its mounting state will be described later.

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

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

The portion where a part of the spherical body is cut off forms a small portion smaller than the outer diameter of the spherical body, and the connecting rod 2 and the piston 4 are connected by the small portion. The connection of both will be described later. In this embodiment, the small-sized portion is formed by mutually parallel planar portions, and the dimension between the two planar portions becomes the size of the small-sized portion smaller than the outer diameter of the sphere (ie, the diameter of the arc).

Therefore, since the spherical portion 2a has a flat surface on one side and the other side, even if the piston 4 and the connecting rod 2 are connected, the flow path of the lubricating oil is short, and since the lubricating oil flows easily, it is formed A structure that can supply lubricating oil to sliding parts.

To connect the connecting rod 2 and the piston 4, a flat surface portion provided on the spherical portion 2a of the connecting rod 2 is used. As shown in Figure 3, the inner spherical surface 4a of the piston 4 is formed into a shape that surrounds the spherical portion 2a of the connecting rod 2 at an angle greater than or equal to 180°, and the opening size L of the inner spherical surface 4a in the A-A section becomes smaller than that of the spherical portion 2a. The size of the outer diameter. On the other hand, the dimension between the two planar portions of the spherical portion 2a is set to be smaller than the opening dimension L of the inner spherical surface 4a. The part of the opening size L is a gap for inserting the spherical part of the connecting rod 2, and the above-mentioned small size part means a part smaller than the opening size L. As shown in FIG.

In this embodiment, two planar portions provided on the spherical body portion 2a are provided substantially in parallel, whereby the two planar 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 relatively rotated to connect them. In addition, in this embodiment, the structure in which two flat parts are provided on the spherical part 2a is formed, but it is not necessarily limited to this, and a size part smaller than the opening size L of the inner spherical surface 4a may also be provided on the spherical part 2a and beyond. Link the two.

The connecting rod 2 and the piston 4 connected in this way will not fall off because the opening size of the inner spherical surface 4a is smaller than the outer diameter of the spherical portion 2a if there is no relative rotation between the two, and the sliding portion can be reduced.

However, if the two are relatively rotated due to some action such as impact, the connection between the connecting rod 2 and the piston 4 will be released. Therefore, in this embodiment, an anti-loosening member 10 is provided to prevent the connection from being disconnected.

The anti-dropping member 10 will be described with reference to FIGS. 6 and 7 . FIG. 6 is a perspective view of the anti-separation member 10 of this embodiment, and FIG. 7 is a perspective view showing a state in which the anti-separation member 10 is assembled and connected to the piston 4 and the connecting rod 2 . In addition, the anti-off member 10 of this embodiment is formed into a shape that also functions as a rotation restricting member that prevents relative rotation between the connecting rod 2 and the piston 4, and one of its characteristics is that it is not only fixed on the connecting rod 2 side, but also fixed on the connecting rod 2 side. Fixed on piston 4 side.

When installing the rotation restricting member, it is possible to fix on the side of the piston 4 and the side of the connecting rod 2 as in the present embodiment, but the method of fixing to the side of the piston 4 is adopted in the present embodiment as described above. In the operating state of the hermetic compressor, the rotational motion of the crankshaft 7 is converted into the reciprocating motion of the piston 4 via the connecting rod 2 to compress the refrigerant in the cylinder 1 . That is, in the reciprocating compressor, with respect to the reciprocating motion of the piston 4, the connecting rod 2 performs a compound motion of the direction of the reciprocating motion of the piston 4 and the direction perpendicular thereto. Therefore, when the rotation restricting member is provided on the side of the piston 4, compared with the case where the rotation restricting member is provided on the side of the connecting rod 2, the fixing is less likely to be disconnected, and reliability can be improved.

In addition, while the piston 4 reciprocates one cycle, the relative positional relationship between the piston 4 and the connecting rod 2 is constantly changing. Here, if the rotation restricting member is provided on the connecting rod 2 side, the position of the rotation restricting member inside the opening of the piston 4 is constantly changed, and the sliding surface tends to increase. Since the increase of the sliding surface can also cause abnormal noise, there is a problem that reliability and quality are also easily reduced. In this embodiment, since the rotation restricting member is provided on the side of the piston 4, these various problems are solved.

As shown in FIG. 6 , the anti-off component 10 of this embodiment has: a first elastic portion 10a, a second elastic portion 10b, a support portion 10c connecting the two elastic portions, and a rotation limiting mechanism for limiting the relative rotation of the connecting rod 2 . Section 10d. In each of these parts, the first elastic portion 10a and the second elastic portion 10b are in contact with the inner peripheral portion of the opening of the piston 4, and the retaining member 10 is supported by elastic force. The state in which the detachment preventing member 10 is attached to the connecting rod 2 and the piston 4 will be described later.

The rotation restricting portion 10d is a portion that forms walls for restricting relative rotation between the connecting rod 2 and the piston 4, and these walls are provided to face each other. In the state where the link 2 is mounted, the flat surface portion provided on the spherical body portion 2a of the link 2 is arranged to face each rotation restricting portion 10d. In this embodiment, since the flat portion is formed to have a size smaller than the opening dimension L of the inner spherical surface 4a provided on the spherical portion 2a, the rotation restricting portion 10d has a substantially flat portion, and the two facing sides The rotation restricting portions 10d are arranged substantially in 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 anti-removal member 10 is attached, the force of the first elastic portion 10a pressing the inner peripheral portion 4b of the piston 4 is generated, and the anti-removal member 10 is fixed inside the opening of the piston 4 by frictional force. Similarly, the second elastic portion 10b is brought into contact with the inner peripheral portion 4b, and the anti-seismic member 10 is firmly fixed inside the opening of the piston 4 . Then, both the elastic parts 10a and 10b generate a force in the direction of sandwiching the spherical part 2a with respect to the rotation restricting part 10d.

By fixing the detachment preventing member 10 in this way, the piston 4 rotates in the cylinder 1, and even if the connecting rod 2 and the piston 4 rotate relative to each other, the connecting rod 2 does not reach the position where it falls off from the piston 4 . The reason is that the distance between the rotation limiting portions 10d facing each other is smaller than the outer diameter of the spherical portion 2a, so if the connecting rod 2 and the piston 4 are to rotate relatively, the outer spherical surface of the spherical portion 2a must contact the rotation limiting portion 10d so that Rotation is restricted.

In addition, in this embodiment, the rotation restricting part 10d forming the wall is fixed by the first elastic part 10a and the second elastic part 10b which are spring structures. Even when 2a collides, excessive deformation of both can be prevented. In addition, when attaching the retaining member 10, deformation of the inner spherical surface 4a of the piston 4 or the spherical portion 2a of the connecting rod 2 can be avoided, and a ball joint structure can be realized.

In addition, since the rotation restricting portion 10d is only formed with a wall, it does not slide against the connecting rod 2 in the normal operating state of the compressor. Therefore, it is possible to suppress loss and generation of abnormal noise due to friction between the two.

In addition, since a plurality of spring members constituting the elastic parts 10a and 10b are arranged in the circumferential direction of the inner peripheral surface of the piston, not only the mounted state of the rotation restricting part 10d can be stably maintained, but also the mounting of the anti-loosening part 10 can be improved. ease. Furthermore, since the elastic portions 10a, 10b are formed in a curved shape along the inner peripheral surface 4b of the piston 4, the rotation restricting portion 10d can be held more stably.

In addition, the upper elastic portion 10a and the rotation restricting portion 10d are connected to the lower elastic portion 10b and the rotation restricting portion 10d by the support portion 10c, because these elastic portions 10a, 10b, and the rotation restricting portion are constituted by one member. 10d and the support portion 10c, therefore, it is possible to maintain the mounting state and improve the ease of mounting.

Fig. 8 is a diagram showing a state where the spherical portion 2a of the link 2 is in contact with the rotation restricting portion 10d, Fig. 8(a) is a front view showing the contact state, and Fig. 8(b) is a perspective view at the time of contact. When the connecting rod 2 and the piston 4 rotate relatively, the spherical part 2a contacts the rotation restricting part 10d. At this time, the rotation restricting portion 10d serves as a wall, and prevents the piston 4 from coming off the connecting rod 2 by restricting excessive rotation. In addition, since the rotation restricting part 10d is elastically supported by the elastic parts 10a and 10b, even if the connecting rod 2 and the piston 4 rotate rapidly, the impact when the spherical part 2a collides with the rotation restricting part 10d is reduced, preventing damaged.

As shown in FIG. 8 , the rotation restricting portion 10 d of this embodiment is formed in a convex shape on the side of the spherical body 2 , and the convex portion 10 d ′ enters an opening on the upper side of the inner spherical surface 4 a of the piston 4 . In addition, the opening on the lower side of the inner spherical surface 4a is also equipped with the anti-removal member 10 so that the convex portion enters, similarly to the upper side. The effect of having such a rotation restricting portion 10d is as follows.

If the rotation restricting part 10d does not have the above-mentioned convex part 10d' but has the same planar shape as a whole, when the relative rotation of the piston 4 and the connecting rod 2 occurs, the first contact with the rotation restricting part 10d is a sphere. The boundary portion 2a' between the arc portion of the portion 2a and the flat portion. Since this portion corresponds to the ridgeline between the arc and the plane, if it collides strongly with the rotation restricting portion 10d, the rotation restricting portion 10d or the boundary portion 2a' may be damaged. In addition, if the rotation restricting portion 10d has a simple planar shape, there is another problem that deformation is likely to occur when contacting.

In the present embodiment, these problems are solved by forming a structure having the convex shape portion 10d'. However, only the convex portion 10d' contributes to the improvement of the strength of the rotation restricting part 10d, but the boundary part 2a' collides with the rotation restricting part 10d first depending on the shape and height. Therefore, the convex shape part 10d' of this embodiment is formed so that it may contact the flat part of the spherical part 2a initially when the piston 4 and the connecting rod 2 rotate relatively. As a specific structure, it is set such that the width of the planar portion of the link ball portion 2a facing the convex portion 10d' is larger than the width of the upper end portion of the convex portion 10d'.

Therefore, by enabling the rotation restricting portion 10d to be in contact with the flat portion, which is a small portion of the spherical portion 2a, not only the strength of the rotation restricting portion 10d but also the overall strength of the anti-off member 10 can be improved, and the risk of damage caused by collisions and the like can be reduced. The damage of connecting rod 2.

In addition, as shown in FIG. 8, the convex portion 10d' is not a structure to close the gap between the spherical portion 2a and the retaining member 10, but to provide a space therebetween to ensure a gap for the inflow and outflow of lubricating oil.

In addition, in this structure, the 1st elastic part 10a and the 2nd elastic part 10b are connected by the support part 10c, and the distance between rotation restricting part 10d, 10d is maintained. The support portion 10 c mutually connects the near sides of both rotation restricting portions, but may cause a problem when colliding with the spherical portion 2 a on the link 2 side. That is, if the rotational force acting in the axial direction of the piston 4 is excessively applied, the spherical portion 2a of the connecting rod 2 may contact and collide with the rotation restricting portion 10d, and the elastic portion 10a or 10b is pressed in, causing the rotation restricting portion 10d In the case of the phenomenon that the inside is open.

At this time, since the above-mentioned relationship between the retaining member 10 and the connecting rod 2 cannot be completely maintained, the retaining member 10 is easily detached from the piston 4 . Therefore, the fall-off preventing member 10 is fixed inside the piston 4 as follows.

FIG. 9 is a cross-sectional view of the connection portion between the connecting rod 2 and the piston 4, and this cross-section corresponds to the A-A cross-section in 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. 9 . The retaining member 10 in this example has an extension portion 10e extending from the support portion 10c toward the inner peripheral surface side of the piston 4 . The end portion of the extension portion 10e is formed by bending toward the opening side of the piston 4, and the direction of the bending may be opposite to that of the elastic portions 10a, 10b. That is, with respect to the elastic portions 10a, 10b located farther inside the piston 4 than the support portion 10c, the end portion of the extension portion 10e is bent toward the opening side of the piston 4 . In addition, it is not particularly limited as long as the curved shape satisfies the above-mentioned conditions and the end portion of the extension portion 10 e is inserted into the groove 4 c provided on the inner peripheral surface of the piston 4 .

In addition, in the state where the end portion of the extension portion 10e is inserted into the groove 4c, since the front end portion of the extension portion 10e is in contact with the shoulder of the groove 4c, depending on the relationship between the curved shape of the extension portion 10e and the falling direction of the fall-off prevention member 10, , the front end portion of the extension portion 10e serves as a support, and it is possible to suppress falling off from the piston 4 . On the other hand, if the end part of the extension part 10e is press-fitted to the position of the groove 4c when attaching the anti-removal member 10, both can be easily engaged, and the attachability can also be improved. Therefore, even when a force acts in a direction in which the detachment preventing member 10 is detached from the piston 4 , this can be suppressed, and detachment of the connection between the piston 4 and the connecting rod 2 can be prevented.

FIG. 10 is a perspective view of the drop-off prevention member 10 in which the extension part 10e is provided on the support part 10c. As shown in the figure, the extension part 10e is provided at the exact middle position between the two rotation restricting parts 10d. The extension part 10e has elastic force similarly to the elastic parts 10a and 10b, and applies elastic force to the inner peripheral surface of the piston 4 while being pressed into the opening of the piston 4 when the anti-slip member 10 is attached. When the extension part 10e is bent and pressed into the position of the groove 4c, the front end part of the extension part 10e is inserted into the groove 4c.

When the front end of the extension part 10e is inserted into the groove 4c and the retaining member 10 is attached to the piston 4, the extension part 10e does not need to apply elastic force to the inner peripheral surface of the piston 4 in the groove 4c. However, in this embodiment, even in the state where the anti-slip member 10 is attached, it is attached so as to apply elastic force to the inner peripheral surface of the piston 4 . By attaching the anti-seismic member 10 in this way, it is possible to effectively prevent the anti-seismic member 10 from falling off from the piston 4 .

The above example shows the case where the extension part 10e is provided on the support part 10c, and the end part of the extension part 10e engages with the groove 4c. A diagram of an example of an extension 10e. FIG. 10 is a longitudinal cross-sectional view of the connection portion of the connecting rod 2 and the piston 4 in this example, and this cross-section corresponds to the B-B cross-section in FIG. 2 in a state where both are connected.

In these examples, since the end of the extension 10e is inserted into the groove 4c, the extension 10e engages with the groove 4c even when a force acts on the direction in which the anti-loosening member 10 falls off from the piston 4, and the end of the extension 10e By serving as a support, it is possible to suppress the fall-off prevention member 10 from the piston 4 . Therefore, the connected state of the connecting rod 2 and the piston 4 can be maintained, and a structure contributing to ensuring reliability can be formed.

In addition, in the example of FIG. 11, since the elastic part 10a, 10b has the extension part 10e, it plays the following role. In this example, since the first elastic portion 10a and the second elastic portion 10b are disposed at positions facing the rotation restricting portion 10d with the spherical portion 2a of the connecting rod 2 interposed therebetween, from the center side in the piston 4 toward the On the outside of the piston 4, the spherical portion 2a, the rotation restricting portion 10d, the first elastic portion 10a (or the second elastic portion 10b), the extension portion 10e, and the groove 4c are arranged in this order. Therefore, even if the spherical portion 2a collides with the rotation restricting portion 10d, a force in the direction of disengaging the extension portion 10e from the groove 4c is less likely to act, thereby making it possible to form a structure in which the retaining member 10 is less likely to fall off.

Hereinafter, while showing another example of these embodiments, the results of studies on the effects of these structures will be described. Here, a case where the radius of the spherical portion 2 a of the ball joint structure is 6.495 mm and the radius of the inner spherical surface 4 a is 6.505 mm will be described as an example. In addition, in the ball joint structure, when the diameter of the spherical part 2a is smaller than the diameter of the inner spherical surface 4a on the side of the piston 4, needless to say, the lubricating oil flows in and out through the gap part caused by the difference in diameter, and the two parts are separated. Lubrication between. In addition, since the center positions of the two do not always exist at the same position, a recess is provided in the innermost part of the piston 4 in particular (see FIG. 9 , FIG. 11 , etc.). The recess functions as a lubricating oil reservoir. For example, as shown in FIG. 9 or 11 , a supply hole for lubricating oil may be provided inside the connecting rod 2 to communicate with the recess.

In addition, as the angle of the inner spherical surface 4 a in the cross section shown in FIG. 3 , an angle θ41 from the axis of the piston 4 is set to 97°, and an angle θ42 shown in FIG. 4 is set to 34°. By specifying θ41 and θ42 in this way, compared with the A-A section, the flow path of the lubricating oil in the B-B section is shortened by about 1/3, and compared with the case where the inner spherical surface 4a is set at 97° over the entire surface, an approximately A structure that triples the amount of lubricating oil flowing through the ball joint structure.

In addition, the groove 4 c provided on the inner peripheral surface of the piston 4 is formed into a rectangle having a width of 1 mm and a depth of 1 mm, and is uniformly provided in an annular shape on the inner periphery of the piston 4 .

When a ball joint structure having such a specific structure is used in a hermetic compressor, the ball joint structure does not come off and good slidability can be maintained. This result was the same for the anti-slip member shown in FIGS. 9 and 10 and the anti-slip member shown in FIG. 11 , and it was confirmed that having each of the above-mentioned structures contributes to the improvement of the efficiency and reliability of the compressor.

As described above, according to each of the embodiments of the present invention, it is possible to easily assemble without deforming the inner spherical surface and the outer spherical surface of the ball joint structure. Furthermore, by cutting away a portion of the inner ball side and the outer ball side of the ball joint mechanism, the sliding area is reduced, and the movement of lubricating oil is facilitated.

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

In addition, since the disconnection of the ball joint structure can be suppressed, it is possible to provide a highly reliable hermetic compressor.

Next, the materials of the piston 4 and the connecting rod 2 constituting the ball joint mechanism section 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 iron-based sintered material sealed with an oxide film. Specifically, after the sintering of the raw material powder, it is processed into an appropriate shape, and the pores inside and on the surface are sealed by the oxide film formed on the surface of the pores by steam treatment, so that the lubricating oil film is not easy to pass through the pores and be blocked. discharge. As will be described later, the oxide of the plugging portion formed by steam treatment also has the effect of increasing the strength of the sintered material.

FIG. 12 shows the results of a sliding test performed on the materials used for the piston 4 and the connecting rod 2 using a ring on block friction tester. In this test, the sliding speed is set to 1.01m/s, and the test load is 123.5N. The sliding test used sintered material 1 and sintered material 2, and the carbon content of each of these sintered materials is different (see the * column of FIG. 12). The combination of the rotating piece and the fixed piece includes the case where the oxide film treatment with water vapor is performed, and also includes the case where the nitriding treatment is performed. As a combination of the rotating piece and the fixed piece, each of No. 1 to No. 5 The combination was tested and 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, which used sintered materials in which only the stationary piece was oxidized, the amount of wear on the rotating piece was large. On the other hand, in No. 3, No. 4, and No. 5, which used sintered materials in which both the rotating piece and the stationary piece were oxidized, the results that the amount of wear was small were obtained. According to this result, the amount of wear can be suppressed to a small amount by using the sintered material sealed with water vapor for the piston 4 and the connecting rod 2 .

Fig. 13 shows the results of the Rockwell B scale apparent hardness measurement of the sintered material. Comparing the combination of materials with less wear in Figure 12, it can be seen that, calculated on the Rockwell B scale, the hardness of the rotating piece is equal to or higher than that of the fixed piece by about 10. According to this combination, it is possible to reduce the amount of wear of the connecting rod 2 which is likely to cause problems due to wear.

From the results of these FIG. 12 and FIG. 13 , as the material of the piston 4 and the connecting rod 2 , a sintered material subjected to oxide film treatment was used.

As a more specific example, an oxide-coated Fe-Cu-C-based sintered material is used as the material for the piston 4, and an oxide-coated Fe-Cu-C-based sintered material is used as the material for the connecting rod 2. , using these pistons 4 and connecting rods 2, a hermetic compressor as shown in FIG. 1 was fabricated. The hermetic compressor was operated for 30 days at an operating speed of 4,900 rpm and an output pressure of 1.6 MPa. No abnormal wear occurred in the ball joint structure and good sliding properties were maintained.

As a second example, a hermetic compressor was manufactured in which an oxide-coated Fe-Cu-C sintered material was used as the material for the piston 4, and an oxide-coated sintered material was used as the material for the connecting rod 2. and nitriding-treated Fe-Cu-C sintered material, operated for 30 days at a rotation speed of 4900 revolutions per minute and an output pressure of 1.6Mpa. No abnormal wear occurred in the ball joint structure. The result of maintaining good sliding properties.

As a third example, a hermetic compressor was manufactured in which a Fe-Cu-C sintered material subjected to oxide film treatment and nitriding treatment was used as the material of the piston 4, and a material of the connecting rod 2 was used. The Fe-Cu-C sintered material treated with oxide film and nitriding was operated for 30 days at an operating speed of 4900 revolutions per minute and an output pressure of 1.6Mpa. In this case, the ball joint structure also Abnormal wear did not occur, and the result was obtained that good sliding properties could be maintained.

These three examples are examined below. Fig. 14 is a measurement result showing the relationship between the depth and the hardness of the piston material and the connecting rod material. As shown in the figure, the horizontal axis represents the depth from the surface of each material, and the vertical axis represents the Vickers hardness HV, thereby showing the relationship between the depth and hardness of the material. As an example (A) of the sintered material 1, the following material is used: a material in which the pores inside and on the surface are sealed by an oxide film formed on the surface of the pores by steam treatment after sintering is further implemented. nitriding treatment. The example (B) shows a material that has been subjected to nitriding treatment instead of oxide film treatment, and the example (C) shows an example that has been subjected to oxide film treatment but not nitriding treatment.

In addition, the example (α) of the sintered material 2 is a material subjected to oxide film treatment and nitriding treatment, and the example (β) shows an example in which an oxide film treatment was performed but no nitriding treatment was performed. These nitriding treatments are performed by general gas salt bath nitriding at a nitriding treatment temperature of about 500 to 600°C.

As can be seen from FIG. 14 , the hardness increases when the nitriding treatment is further performed on the material on which the oxide film has been formed by the water vapor treatment. Therefore, it is preferable that the sintered material used for the connecting rod 2 is sealed with steam and then nitrided. At this time, the sintered material that has been nitrided may be used for the piston 4 (the third example above), but the piston 4 may not be nitrided (the second example above) in order to prevent the surfaces from being made of the same material.

On the other hand, when nitriding treatment is performed without steam sealing treatment, as shown in FIG. 14 , the sintered material is hardened to the inside through the micropores in the sintered material, and the material as a whole becomes brittle. Therefore, a decrease in reliability is likely to occur due to breakage of the connecting rod 2 or the like.

In the present embodiment, the part close to the surface maintains sufficient hardness to ensure wear resistance, but the inner hardness is lower than the part close to the surface in terms of Vickers hardness, and the connecting rod 2 having excellent toughness is obtained. Therefore, a hermetic compressor excellent in reliability can be provided by performing nitriding treatment after the sealing treatment by steam treatment.

In addition, the same effects can be expected by performing carburizing treatment or sulfurizing and nitriding treatment instead of the above-mentioned nitriding treatment.

In order to carry out the surface treatment as described above, the following dimensional considerations are required in manufacturing. That is, when manufacturing the connecting rod 2, firstly, the raw material powder is sintered and processed into an appropriate shape. At this time, it is necessary to make the diameter of the portion of the connecting rod 2 that becomes the spherical portion 2 a smaller than the diameter of the inner spherical surface 4 a of the completed piston 4 . Conversely, it is necessary to make the diameter of the portion of the piston 4 that becomes the inner spherical surface 4 a larger than the diameter of the spherical portion 2 a of the connecting rod 2 when completed. Thereafter, steam treatment or the like is performed so that the diameter of the spherical body portion 2a is increased by a corresponding amount and the diameter of the inner spherical surface 4a is decreased by a corresponding amount.

Next, the fall-off preventing member 10 will be described. The connecting rod 2 achieves further improvement in reliability by making the surface hardness smaller than that of the detachment preventing member 10 . As shown in FIG. 8 , the portion where the ball portion 2 a of the connecting rod 2 is in contact with the anti-loosening member 10 is a plane portion provided on the ball portion 2 a, and the plane portion does not slide with the inner spherical surface 4 a of the piston 4 in a normal operating state. part. Therefore, even if the flat portion is worn to some extent, the sliding relationship with the piston 4 does not change greatly.

On the other hand, the anti-slip member 10 is worn due to contact with the spherical portion 2a, and when the thickness of the rotation restricting portion 10d becomes thin, the anti-separation member 10 is damaged, and the connection between the piston 4 and the connecting rod 2 may be released. In this case, the function as the hermetic compressor is damaged, which causes the failure. In the present embodiment, reliability improvement is achieved by using SUS301-1/4H having a hardness higher than the surface hardness of the connecting rod 2 for the fall-off preventing member 10 .

During the actual operation of the hermetic compressor of the present embodiment described above, care must be taken not to increase the temperature of the sliding portion. The reason is that an excessive rise in the temperature of the sliding portion promotes wear, resulting in a decrease in reliability. In particular, in the case of the present example using a surface-treated sintered material, the temperature of the sliding portion during operation was kept at 150° C. or lower in order to prevent a decrease in reliability caused by an excessive temperature rise. The same test as the above-mentioned first to third examples was conducted, and after the operation, when the temperature of the sliding part was kept at 150°C or lower, abnormal wear did not occur in the ball joint structure, and good sliding properties were obtained. result.

In addition, the lubricating oil used in actual operation will be described. As in the above-mentioned embodiments, in order to maintain an oil film on the surface of the piston 4 and the connecting rod 2 using the sintered material subjected to the sealing treatment (oxidation film treatment) or nitriding treatment with water vapor, as lubricating oil, used in Ester-based synthetic oils with good adsorption on the surface of the nitrided film are more effective. In order to maintain the oil film of lubricating oil supplied to the sliding part, sealing treatment is necessary. Using ester-based synthetic oil with good affinity with the nitride film will not only reduce sliding loss, but also suppress abnormal wear.

As an example, when hydrocarbon-based R600a (isobutane) was used as the refrigerant and ester-based synthetic oil was used as the lubricating oil, abnormal wear did not occur in the ball joint structure and good sliding properties were maintained. In addition, even if a mixture of mineral oil and ester-based synthetic oil is used as lubricating oil, good sliding properties can be maintained, and higher reliability can be obtained compared to the case where only mineral oil is used as lubricating oil.

According to the above-described embodiments, since abnormal wear of the inner spherical surface and the outer spherical surface of the ball joint structure can be suppressed, long-term reliability of the hermetic compressor can be ensured. In addition, it is also possible to reduce the sliding loss during the operation of the hermetic compressor, and as a result, it contributes to the improvement of the efficiency of the hermetic compressor. Therefore, a highly reliable hermetic compressor suitable for power saving can be provided.

Claims (8)

1. a closed compressor is taken in compressing mechanism and motor in seal container, and described closed compressor has: bent axle, and its conduction is from the rotating force of described motor; Piston, it is at this crankshaft side opening and have inner ball surface in this opening; And connecting rod, the one end is the spheroid portion that is connected with described inner ball surface, the other end is the bearing portion that is connected with described bent axle, and has a bar portion that connects these two ends, described inner ball surface forms the central angle of circular arc of substantially horizontal greater than the central angle of the circular arc of vertical direction, and described spheroid portion has the small size portion of size less than the opening size of the substantially horizontal of described inner ball surface, and described inner ball surface and described spheroid portion link by the ball-and-socket joint structure, sealing formula compressor is characterised in that

Have two rotation limitation part with position that described small size portion faces mutually, described two rotation limitation part limit the relative rotation between described connecting rod and the described piston,

This rotation limitation part is installed in described piston, and when described relative rotation, can contact with described small size portion,

Described small size portion is formed by the planar surface portion that is parallel to each other, and the size between this planar surface portion is had: with the identical size of described part that has less than the size of the diameter of circular arc,

Described two rotation limitation part form the convex form with plane shape of facing mutually with described planar surface portion, and under the state that described connecting rod has been installed, the planar surface portion that is arranged at the spheroid portion of described connecting rod is faced configuration mutually with described two rotation limitation part.

2. closed compressor according to claim 1 is characterized in that,

Have spring section between the inner peripheral surface in the opening of described rotation limitation part and described piston, described rotation limitation part is kept by the elastic force from described spring section.

3. closed compressor according to claim 2 is characterized in that,

Described spring section and described rotation limitation part are set up as the part of the anticreep parts that are made of single part, these anticreep parts have the extension part that the inner peripheral surface in the opening of piston extends, and the end of described extension part is held by entering in the groove that is located at described inner peripheral surface.

4. closed compressor according to claim 2 is characterized in that,

Described spring section is a spring members as follows, that is, its outer circumferential face that contacts with the inner peripheral surface of described piston is the curved surface shape and is shape along described inner peripheral surface.

5. closed compressor according to claim 3 is characterized in that,

Described spring section and described rotation limitation part are configured in the top of described connecting rod and the both sides of below, the rotation limitation part of top and the size between the rotation limitation part of below are greater than described small size portion, and described spring section is to described rotation limitation part generation power on the direction of the described spheroid of clamping portion.

6. closed compressor according to claim 4 is characterized in that,

Have a plurality of described spring members, and described spring members is made of the spring on the Zhou Fangxiang of the inner peripheral surface that is configured in described piston.

7. closed compressor according to claim 5 is characterized in that,

Have support, described support connect above spring section and the rotation limitation part with below spring section and the rotation limitation part between, constitute these spring section, rotate limitation part and support by single part.

8. closed compressor according to claim 7 is characterized in that,

Described extension part is arranged at described support.

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