CN100516518C - hermetic compressor - Google Patents

Abstract

The invention provides a hermetic compressor has stability, high performance and high reliability, ball articulated device with lower friction loss made up of connecting rod and interlink structure of piston. The hermetic compressor of this invention including: hermetic vessel and a compress unit in the hermetic vessel, electromotion unit and a winch device transmits rotating force of the electromotion unit to the compress unit, the compress unit comprising cylinder and piston doing reciprocating motion in the cylinder, the winch device has a connecting rod connects with the piston, a ball set on the connecting rod ball articulated with ball connecting hole set on the piston rotating and gliding freely, and lubricating oil feeded to the ball articulated gliding part, characterized in one of the piston, the connecting rod is alloy which major component is iron, material surface layer hardness of the other one is more than 1.5 times in Vickers hardness relative to that of the alloy which major component is iron.

Description

hermetic compressor

technical field

The present invention relates to a hermetic compressor used in refrigerators, air conditioners, etc., and more particularly to a hermetic compressor with a reciprocating piston.

Background technique

Conventionally, as a ball joint structure on a piston and a connecting rod of a compressor, it is known that a spherical receiving hole (ball receiving hole) and a ball are implemented on both sides or one of them as in JP-A-2003-214343 (Patent Document 1). Nitriding treatment and manganese phosphate treatment, and the structure using high-carbon chromium steel on the spherical surface.

However, the configuration of Patent Document 1 (Patent Document 1: JP-A-2003-214343) has the following problems.

In the structure of Patent Document 1, the high-carbon chromium steel material used on the spherical surface has high hardness and is difficult to process. Also, the passage of lubricating oil supplied to spherical bearings (balls and ball receiving holes) which is a ball joint structure becomes the contact surface of the piston and cylinder when the piston is pulled from the cylinder and narrows the gap constituting the passage of lubricating oil.

There is a possibility that lubricating oil cannot flow sufficiently due to this gap alone, and thus the temperature of the spherical bearing (balls and ball receiving holes) may rise and damage may occur.

Also, in the hermetic compressor, after the container, that is, the box, is inserted into the internal mechanism, it is sealed by welding.

As a result, molten spray during welding, that is, spatter particles are inevitably mixed in and remain in the container. It is known that if the remaining splash particles are mixed into the circulating oil and enter the sliding part, the surface of the sliding part is damaged, and seizure occurs, causing wear or seizure.

In addition, if the grinding powder generated on each sliding surface is also mixed into the lubricating oil, and especially enters into the narrow sliding part such as the ball joint, it will cause wear or adhesion similar to the particles, and the reliability of the compressor will be significantly reduced. Spend.

Contents of the invention

The present invention was made in view of the above-mentioned conventional problems, and its purpose is to connect the piston and the connecting rod with spherical bearings, supply lubricating oil sufficiently, and improve the performance and reliability of the compressor by using a material with high wear resistance.

The present invention is a hermetic compressor, which has a connecting rod connected with a piston, a ball arranged on the connecting rod and a ball receiving hole arranged on the piston are freely rotatable and slidingly hinged by the earth, and the sliding part of the ball hinge is lubricated The oil supply is characterized in that one of the piston and the connecting rod is an alloy material mainly composed of iron, and the other material is a material harder than the hardness of the surface layer of the alloy material mainly composed of iron.

According to the present invention, the wear of the ball joint can be reduced, and a highly reliable compressor can be obtained.

Next, the present invention will be described in more detail.

The present invention is characterized in that one of the piston and the connecting rod is an alloy material mainly composed of iron, and the other material is a material having a hardness 1.5 times or more of the Vickers hardness of the alloy material mainly composed of iron.

Furthermore, in the present invention, lubricating oil is supplied through the oil supply port inside the connecting rod provided on the ball joint, and an oil film is formed on the contact surface (ball and ball receiving hole) between the piston and the connecting rod to reduce the oil loss. friction, and improve efficiency, and reduce the solid contact between the piston and the connecting rod through the oil film, so that the wear reliability can be improved.

In addition, in order to improve the formability of the inner spherical surface of the ball receiving hole, it is preferable to use iron-based sintered material on the side of the piston. On the one hand, the connecting rod is preferably made of sintered material for forming and processing the outer spherical surface of the ball and forming the oil supply port, but sintered material can also be used in combination in consideration of wear durability.

In order to compress the gas by using the rotational force from the crank pin as a reciprocating force, the iron-based sintered material must have sufficient strength for the piston, the connecting rod, or both, and the density of the iron-based sintered material must be 6.6g/cm ³ above.

In order to provide sufficient oil supply and effectively form an oil film, the sintered material used in the assembly of the ball joint must be made higher density.

After sintering the raw material powder, it is processed into a suitable shape and subjected to steam treatment, and the oxide film formed on the surface of the cavity seals the internal and surface cavities, and makes it difficult for the lubricating oil film to be discharged through the cavities. The oxide of the plugging part treated by water vapor has the effect of preventing adhesive wear while improving the strength of the sintered material.

Since a large load may be temporarily applied to the ball joint due to the operating conditions of refrigerant compression, one surface is nitrided so that the same materials do not contact each other even if solid contact occurs on the friction surface. Vulcanization or vulcanization, or as a mixed layer of these, different materialization is performed.

In the lubricating oil supplied to the sliding parts (balls and ball receiving holes), abrasive particles generated by the running-in operation at the beginning of use in the compressor or temporary high-load operation or splashed particles when the casing is sealed are mixed. Grinding powder, because the work-hardened layer on the surface of the sliding part (ball and ball receiving hole) on the softer side falls off or the falling off grinding powder deforms in the gap between the sliding surface, so its hardness becomes 1.5 times that of the raw material times to 2 times.

In the sliding part (ball and ball receiving hole), by making the surface hardness of the harder side more than 1.5 times that of the softer side, the surface of the harder side material is prevented from becoming rough, and the grinding edge makes the harder side The surface deformed edge of the soft material is discharged out of the friction surface through rotation or flow driven by lubricating oil.

Also, since the softer material is ground by the surface shape of the harder material after the mill powder is discharged, it is possible to restore a surface similar to the smooth shape before the mill powder is formed and discharged.

From the perspective of improving compression efficiency, the gap between the sliding part (ball and ball receiving hole) during normal operation should not exceed 10 microns at most, and the size of the particles generated in the gap or entering together with the lubricating oil is about It is less than 10 microns. Therefore, in order to prevent the harder material from being deformed and worn by the rotating particles, ensure that the effective depth of the surface diffusion treatment is more than twice the size of the surface particles.

Splash particles are formed by solidification of the melted iron box material in the space when the box is welded. They are roughly spherical and have a Vickers hardness of about 800. Although it is also possible to improve the welding method or install a filter on the oil supply path, the filter also reduces the oil supply efficiency and deteriorates the lubrication. Therefore, in order to prevent damage to the ball joint due to flying particles, it is preferable to further increase the hardness of the harder side.

Iron-based materials increase hardness and improve wear resistance by quenching, but since the surface is made of metal, when combined with iron-based sintered materials, it is easy to cause adhesion with the target material. By further nitriding or carburizing the surface to increase hardness, and further making it non-metallized to prevent deformation and wear caused by bonding and grinding with the target material. Sulfide treatment is also effective in demetallization. These diffusion treatments may also be combined appropriately. In the diffusion treatment, in order to maintain the internal hardness after quenching, it is necessary to be able to temper at a temperature higher than the diffusion treatment temperature.

In order for the lubricating oil used on the structure of the present invention to firmly maintain the oil film, it is suitable to use ester synthetic oil with good adsorption force on the surface of iron-based sintered materials and nitriding or carburizing or vulcanization. Even if mineral oil and ester oil are mixed, ester molecules can selectively adhere to the surface of the sliding part and prevent solid contact.

In order to maintain the oil film of the lubricating oil supplied, sealing treatment is required. However, by filling the unavoidably remaining cavities with lubricating oil, even when the cavities are exposed to the surface due to wear, the filled lubricating oil can prevent metal contact at the worn part and prevent wear.

In addition, in the compressor having the connecting structure of the piston and the connecting rod, the present invention adopts a ball joint structure in which the connecting structure (ball and ball receiving hole) does not fall off, and further makes a structure in which lubricating oil is supplied from the inside of the connecting rod. .

According to the present invention, it can be an effective hermetic compressor when compressing non-chlorinated refrigerants such as isobutane refrigerant and R134a, which do not have an anti-wear effect by the refrigerant itself.

According to the above configuration, a ball joint mechanism with good lubricity can be configured, and the performance and reliability of the hermetic compressor 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 diagram showing the inner structure of the piston according to the embodiment of the present invention.

Fig. 3 is an A-A sectional view of Fig. 1 related to an embodiment of the present invention.

Fig. 4 is a B-B sectional view of Fig. 1 related to an embodiment of the present invention.

Fig. 5 is a perspective view of a link related to the embodiment of the present invention.

Fig. 6 is a perspective view of the backstop related to the embodiment of the present invention.

Fig. 7 is a diagram showing an assembled state of a piston and a connecting rod according to the embodiment of the present invention.

Fig. 8 is a diagram showing an assembled state of a piston and a connecting rod according to an embodiment of the present invention with a backstop added.

9 is a cross-sectional view showing the relationship between the piston, the connecting rod and the backstop according to another embodiment of the present invention.

Fig. 10 is a perspective view of a backstop related to another embodiment of the present invention.

11 is a sectional view of a crankshaft and a crankshaft bearing according to another embodiment of the present invention.

Fig. 12 is a graph showing the results of wear tests of piston materials and connecting rod materials according to Examples of the present invention.

Fig. 13 is a graph showing the results of hardness measurement of sintered materials according to Examples of the present invention.

Fig. 14 is a graph showing the results of hardness measurement of various steel materials according to Examples of the present invention.

Fig. 15 is a graph showing the results of wear tests of the piston material and the connecting rod material according to the examples of the present invention.

1-cylinder, 4-piston, 2-connecting rod, 2a-ball, 4a-ball receiving hole

Detailed ways

Hereinafter, each embodiment will be described respectively with reference to the drawings.

In Fig. 1, it is shown that the piston 4 combined with the crankshaft 7a through the connecting rod 2 reciprocates in the piston 1 of the compression unit integrally formed with the bearing part 1a and the frame 1b in the closed container to form an applicable version of the compression unit. Invented reciprocating hermetic compressor.

A stator 5 and a rotor 6 constituting an electric motor, which is an electric unit, are attached to the lower portion of the frame 1b. A crankshaft 7a is provided at a position eccentric from the rotation center of the rotor shaft 7 of the rotor 6 .

The rotor shaft 7 penetrates and is attached to the bearing portion 1a of the frame 1b. The rotor shaft 7 is directly connected to the rotor 6 , and the rotation of the rotor shaft 7 (here, clockwise rotation) causes the piston 4 to reciprocate by means of the connecting rod 2 .

The crankshaft 7a including the rotor shaft 7 and the connecting rod 2 are referred to as a crank mechanism.

The piston of the compression unit will be described in detail below with reference to FIG. 2 , FIG. 3 , and FIG. 4 .

FIG. 2 is a view showing the inside of the piston 4 viewed from the rotor shaft 7, and has a ball receiving portion (inner spherical surface) 4a. Fig. 3 is a cross-sectional view along line A-A of Fig. 2 . Fig. 4 is a B-B sectional view of Fig. 2 .

Although the ball receiving portion (inner spherical surface) 4a of the piston is in the shape of wrapping the tip of the ball (outer spherical surface) 2a of the connecting rod 2 at an angle of 180 degrees or more in the A-A section, it is only 180 degrees in the B-B section. The following angles enclose the shape of the ball (outer spherical surface) 2a of the link 2.

Therefore, since the B-B section has a ball joint structure whose sliding area is smaller than that of the A-A section, and the path through which the lubricating oil passes is shorter, the lubricating oil can flow easily and the lubricating oil can be sufficiently supplied.

The connecting rod will be described below based on FIG. 5 .

FIG. 5 is a perspective view of the connecting rod 2 . The connecting rod 2 is composed of a ball (outer spherical surface) 2a inserted into the ball receiving hole (inner spherical surface) 4a of the piston 4, a crank bearing part 2b inserted into the crankshaft 7a, and a rod part 2c connecting the ball (outer spherical surface) 2a and the crank bearing part 2b. constitute.

The oil supply hole 2d is provided so as to pass through the interior of the ball (outer spherical surface) 2a and the rod portion 2c. Lubricating oil flows through the oil supply hole 2d and is supplied from the crank bearing portion 2b to the sliding portion of the ball (outer spherical surface) 2a.

In addition, the ball (outer spherical surface) 2a has the same structure as the ball receiving hole (inner spherical surface) 4a of the piston 4, in which a part of the spherical surface is notched. Therefore, the path through which the lubricating oil passes is short, the lubricating oil is facilitated to flow, and the lubricating oil can be sufficiently supplied.

Next, the backstop will be described with reference to FIG. 6 , FIG. 7 and FIG. 8 .

Fig. 6 is a perspective view showing a backstop. Fig. 7 is a perspective view of a state in which the backstop is assembled on the ball joint structure. FIG. 8( a ) is a view of the backstop assembled as a ball joint structure viewed from the side of the crankshaft bearing. Fig. 8(b) is the same perspective view as Fig. 7 in which the viewing angle is changed.

Before describing the backstop, the ball (outer spherical surface) of the connecting rod and the ball receiving hole (inner spherical surface) of the piston will be additionally described.

The ball (outer spherical surface) 2 a symmetrically has a pair of flat surfaces 2 c formed along the length direction of the connecting rod 2 .

The ball receiving hole (inner spherical surface) 4a has a pair of insertion cutouts 4b formed to be equal to or slightly larger than the thickness and width between the two flat surfaces 2c. The width of the insertion incision 4b is L. As shown in FIG. The piston 4 has a pair of substantially semicircular holding recesses 4c outside the pair of insertion cutouts 4b.

The piston 4 has a circular hole 4f larger than the ball receiving hole (inner spherical surface) 4a in front of the position where the ball receiving hole (inner spherical surface) 4a is formed. That is, the ball receiving hole (inner spherical surface) 4a is formed so as to fall into the center bottom of the circular hole 4f.

An oil reservoir 4d is formed on the center bottom of the ball receiving hole (inner spherical surface) 4a. Lubricating oil supplied through the oil supply hole 2d stays on the oil storage portion 4d. The sliding surface between the ball receiving hole (inner spherical surface) 4a and the ball (outer spherical surface) 2a is sufficiently wetted by the lubricating oil remaining there, and normal operation is performed.

By inserting the ball (outer spherical surface) 2a into the ball receiving hole (inner spherical surface) 4a and turning the ball (outer spherical surface) 2a so that the flat surface 2c enters the insertion cutout 4b, the ball receiving hole (inner spherical surface) 4a and ball (outer spherical surface) 2a normally slide the anti-falling of the ball joint that the mode combines.

The backstop 10 prevents the ball (outer spherical surface) 2a hinged by the ball from falling out of the ball receiving hole (inner spherical surface) 4a, and prevents the ball (outer spherical surface) 2a from returning.

The backstop 10 has a pair of fitting legs 10a inserted into a pair of holding recesses 4c provided on the piston 4, and a connecting portion 10b straddling the pair of fitting legs 10a. The pair of fitting legs 10a has a flat plate portion 10a1 and two arc portions 10a2 bent outward from both ends of the flat plate portion 10a1 and extending close to each other while drawing an arc.

Further, at the center of the flat plate portion 10a1, there is a recessed portion 10a3 provided to be recessed inward and joined to the flat surface 2c of the ball (outer spherical surface) 2a. The backstop 10 is formed by bending a steel plate, and is made of a springy metal plate including a steel plate or a phosphor bronze plate.

As shown in FIGS. 7 and 8 , the backstop 10 is installed on the piston 4 . The backstop 10 inserted through the circular hole 4f of the piston 4 is held by inserting the fitting leg 10a into the holding recess 4c. Since the two arcuate portions 10a2 are flexibly fitted into the holding concave portion 4c by virtue of elasticity, the fitting leg 10a is less likely to come off.

By using the backstop 10 provided with the arc portion 10a2 having such elasticity, the ball joint structure can be assembled without deforming the ball receiving hole (inner spherical surface) 4a of the piston 4 and the ball (outer spherical surface) 2a of the connecting rod 2, And constitute a ball hinge structure with excellent sliding properties.

In a state where the backstop 10 is mounted on the piston 4, the concave portion 10a3 of the flat plate portion 10a1 is coupled with the flat surface 2c of the ball (outer spherical surface) 2a. Therefore, the rotation of the ball (outer spherical surface) 2a in the direction of releasing the engagement between the flat surface 2c and the recessed portion 10a3 is prevented. By preventing the rotation, the ball joint in which the ball (outer spherical surface) 2a and the ball receiving hole (inner spherical surface) 4a are combined can be held without falling off.

The rotation of the ball (outer spherical surface) 2a with respect to the ball receiving hole (inner spherical surface) 4a is a rotational motion such as the swing of the shaft portion 2c of the link 2 .

Other embodiments of the backstop will be described below with reference to FIG. 9 and FIG. 10 .

This backstop 10 is characterized in that, as shown in FIG. 10 , locking claws 10c are provided on the connecting portion 10b. As for other parts, it has the same structure as the above-mentioned backstop.

The piston 4, as shown in FIG. 9, is characterized in that an annular locking groove 4g is provided in the circular hole 4f, and other parts have the same structure as the above-mentioned piston.

The engagement of the locking claw 10c with the locking groove 4g prevents the backstop 10 from falling out of the circular hole 4f. Since the locking of the locking claw 10c is added to the holding by the elasticity of the two circular arc portions 10a2, the backstop 10 is held more reliably.

Next, another embodiment related to the supply of lubricating oil will be described with reference to FIG. 11 .

The crankshaft 7a has an oil flow hole 110 for lubricating oil extending in the axial direction and an oil flow hole 111 penetrating toward the outer periphery. In addition, the crankshaft bearing portion 2b has an annular oil groove 112 on the sliding surface. An oil supply hole 2 d is formed in communication with the oil groove 112 .

In the crank bearing portion 2b, lubricating oil flowing through the oil flow hole 110 is supplied through the oil flow hole 111 and the oil groove 112, and wets the sliding surface of the crank bearing portion 2b and the crankshaft 7a. Since the lubricating oil in the oil groove 112 is also injected into the oil supply hole 2d, the sliding surface between the ball receiving hole (inner spherical surface) 4a and the ball (outer spherical surface) 2a is also wetted.

Since the oil groove 112 constituting the oil reservoir is provided in the crank bearing portion 2b, the supply of lubricating oil to the sliding surface between the crank bearing portion 2b and the crankshaft 7a is smoothly performed. Also, since the oil supply hole 2d communicates with the oil groove 112 constituting the oil reservoir, the supply of lubricating oil to the sliding surface between the ball receiving hole (inner spherical surface) 4a and the ball (outer spherical surface) 2a is carried out smoothly. .

Next, materials used to secure the reliability of the structural ball joint suitable for sufficient supply of lubricating oil will be described.

FIG. 12 shows the results of a sliding test of the materials used for the piston 4 and the connecting rod 2 by a ring block friction tester.

This test is carried out in lubricating oil, the sliding speed is set at 1.01m/s and the test load is set at 123.5N. From the test results, it was confirmed that when the sintered material 4 in which the sealing process was not performed on the material of the connecting rod 2 and only the sealing process was performed on the material of the piston 4 was used, the amount of wear was large.

The reason for this is that the oil film cannot be formed because the holes are not sealed. On the one hand, in the case of using cast iron without voids or sintered material with sealing treatment on both sides, there is a tendency that the material of the connecting rod 2 will be less worn, and the material of the connecting rod 2 can meet the necessary requirements. critical amount of wear.

However, it was found that the wear of the material of the piston 4 also increased. In the case of the same sintered material, when combining the sintered material 4SN nitrided on the material of the connecting rod 2 and the sintered material 8S of the material of the unnitrided piston 4, although the material of the nitrided connecting rod 2 The wear threshold was not exceeded, but increased wear of the material of the non-nitrided piston 4 resulted.

In the case of nitriding both sides, no matter which side wear has increased. In the target material A3 and the sintered material 8S, which were hardened by the following heat treatment (treatment condition 103) on the die steel, the material of the connecting rod 2 and the material of the piston 4 both had improved wear resistance, and did not Wear threshold exceeded. Through these tests and experimental studies, it was found that the ratio of the hardness of the surfaces of the materials combined greatly affects the improvement in wear resistance.

Fig. 13 shows the results of surface hardness measurement of the sintered material. The ratio of the surface hardness of the sintered material 4SN to that of the sintered material 8S is about 1.4 times, and it can be presumed that the wear critical value shown in FIG. 12 can be satisfied by increasing the hardness ratio.

Table 1

Treatment conditions and hardness measurement results of quenched and nitrided steel materials for molds

processing number Quenching temperature Tempering temperature Nitriding method Nitriding temperature The average temperature of the surface layer The average temperature inside the material 101 1030℃ 200℃ Gas carbonitriding method 575°C HV750 HV500 103 1030℃ 520°C Gas carbonitriding method 575°C HV760 HV550 104 1030℃ 520°C Liquid nitriding method 480°C HV900 HV680

Table 1 summarizes the treatment conditions and hardness measurement results of the steel quenched and nitrided materials for molds related to the examples of the present invention.

Table 1 shows the surface layer and internal hardness of the target materials A1, A3, and A4 that were subjected to heat treatment and nitriding treatment using cold-rolled die steel equivalent to SKD11 in JIS in order to further increase the hardness ratio The measurement results.

It is known that increasing the quenching temperature increases the surface hardness, and lowering the nitriding temperature increases the hardness of both the surface layer and the inside. Furthermore, it is known that if the material with the highest hardness (target material A4) is used, the hardness ratio can be approximately tripled, and as shown in FIG. .

Since increasing the hardness of the target material means increasing the processing difficulty at the same time, the study of the target material was carried out in view of the processability. Based on the target materials A1, A3, and A4 in Table 1, the SCM415 material (surface nitriding hardened steel) in JIS was used, and the target materials B6 and B8 were produced by nitriding and high-frequency induction heating and quenching.

The results of the wear test in combination with the sintered material 8S under the same conditions as in FIG. 12 are shown in FIG. 15 .

From this result, it can be seen that when the ratio of the hardness of the surface layer is 1.5 times or more, desired durability can be obtained with respect to normal wear.

As described above, if the various embodiments of the present invention are applied, abnormal wear does not occur on the ball receiving hole (inner spherical surface) 4a and the ball (outer spherical surface) 2a of the ball joint structure, so that the sealing performance of the hermetic compressor can be ensured. Long-term reliability, and the efficiency of the hermetic compressor can be improved by reducing the sliding loss during the operation of the hermetic compressor.

In addition, using object materials B6 and B8, respectively combining them with sintered material 8S, the sliding test was repeatedly performed by a ring block friction tester in the same manner as in FIG. 12 . The repeated test was carried out in the lubricating oil mixed with the spatter welding slag during welding of low carbon steel adjusted to an average particle size of 10 microns, the sliding speed was set at 1.01m/s and the test load was set at 123.5N, and the short-term test.

Observation of the friction surface after the test showed that although abrasive wear marks, which were scars caused by splashed particles, were observed on the surface of the subject material B6, almost no abrasive wear marks were observed on the surface of the subject material B8.

From the above results, it was decided to use a sintered material that was steam-treated and sealed as the material for the piston 4, and a material that was steam-treated and then nitrided on the sintered material as the material for the connecting rod 2. Die steel is quenched and then nitrided below the tempering temperature after high-temperature tempering.

(Embodiment 1)

First, a sintered material of Fe-Cu(1-2%)-C(0.7-1.0%) subjected to sealing treatment by steam treatment was used as the material of the piston 4, and it was used as the connecting rod 2. The material used in the compressor is an iron-based alloy.

The iron-based alloy is a smelting material, in which Cr(11-13 wt%)-Mo(0.8-1.2 wt%)-Mn(0.3-0.6 wt%)-C(0.6-1.6 wt%) and other components including The iron alloy of the remaining element iron was quenched at 1010°C to 1040°C, tempered twice at 520°C for 2 hours, and nitriding was performed in a salt bath at 480°C for 90 minutes.

In the refrigeration cycle equipped with this hermetic compressor, isobutane was sealed as a refrigerant and ester oil was sealed as a lubricating oil, and the operation speed was 4900 revolutions per minute and the discharge pressure was 1.6Mpa. After 30 days, as a result, no wear occurred on the ball joint structure, and the result was obtained that good lubricity could be maintained.

In addition, a similar test was carried out in which the discharge pressure was increased to 2.0 MPa. As a result, abnormal wear did not occur on the ball joint structure, and good characteristics could be maintained.

In addition, a compressor in which splash particles were added to lubricating oil at 10 times the upper limit of the management was manufactured, and it was operated under the same conditions for 5 days. As a result, the rotation did not stop and the operation was stable. No abnormal wear other than minor scratches.

Claims (20)

1. A hermetic compressor comprising a closed container, a compression unit accommodated in the closed container, an electric unit, and a crank mechanism for transmitting the rotational force of the electric unit to the compression unit, The compression unit has a cylinder and a piston reciprocating in the cylinder, The crank mechanism has a connecting rod connected to the piston, The ball provided on the connecting rod and the ball receiving hole provided on the piston are freely rotatable and slidably jointed by the earth, and the sliding part of the ball joint is supplied with lubricating oil, and it is characterized in that, One of the piston and the connecting rod is an alloy material mainly composed of iron, The hardness of the other material is 1.5 times or more in Vickers hardness with respect to the hardness of the surface layer of the alloy material mainly composed of iron. 2. The hermetic compressor according to claim 1, characterized in that, The alloy material mainly composed of iron is a sintered material, and the density of the sintered material is 6.6 g/cm3 or above. 3. The hermetic compressor according to claim 2, characterized in that, The sintered material is sealed through the oxide film. 4. The hermetic compressor according to claim 3, characterized in that, The sealing treatment is a sealing treatment of cavities remaining in the sintered material by steam treatment after molding and cutting of the piston or the connecting rod. 5. The hermetic compressor according to claim 1, characterized in that, In the other material, any one of nitriding treatment, carbonization treatment, carburizing treatment, and sulfurizing and nitriding treatment is applied to the surface diffusion treatment on the front surface or the sliding portion. 6. The hermetic compressor according to claim 5, characterized in that, The nitride layer or sulfide layer or the mixed layer of sulfide and nitride formed by the surface diffusion treatment is a surface hardened layer, and the range of forming the hardness of 1.5 times or more from the outermost surface is at least 20 microns or more. 7. The hermetic compressor according to claim 5, characterized in that, The surface diffusion treatment is a surface diffusion treatment performed below the tempering temperature of the material. 8. The hermetic compressor according to claim 1, characterized in that, The lubricating oil is an ester lubricating oil or a lubricating oil mixed with an ester lubricating oil and mineral oil. 9. The hermetic compressor according to claim 2, characterized in that, Ester lubricating oil or lubricating oil mixed with ester lubricating oil and mineral oil fills and impregnates the cavities remaining on the sintered material. 10. The hermetic compressor according to claim 1, characterized in that, The refrigerant compressed in the cylinder is designated as isobutane. 11. The hermetic compressor according to claim 1, characterized in that, As the refrigerant compressed in the cylinder, a non-chlorine refrigerant such as R134a having compatibility with ester lubricating oil is used. 12. The hermetic compressor according to claim 1, characterized in that, There is an oil supply hole longitudinally penetrating through the connecting rod and connected to one side of the sliding portion of the ball. 13. A hermetic compressor comprising a closed container, a compression unit accommodated in the closed container, an electric unit, and a crank mechanism for transmitting the rotational force of the electric unit to the compression unit, The compression unit has a cylinder and a piston reciprocating in the cylinder, The crank mechanism has a connecting rod connected to the piston, The ball provided on the connecting rod and the ball receiving hole provided on the piston are freely rotatable and slidably jointed by the earth, and the sliding part of the ball joint is supplied with lubricating oil, and it is characterized in that, The ball symmetrically has a pair of flat faces formed along the length direction of the link, The ball receiving hole has a pair of cutouts for insertion formed equal to or slightly larger than the thickness between the two flat surfaces, The ball inserted into the ball receiving hole is rotated so that the flat surface enters the insertion cutout to form a ball joint detachment prevention, One of the piston and the connecting rod is an alloy material mainly composed of iron, The hardness of the other material is 1.5 times or more in Vickers hardness with respect to the hardness of the surface layer of the alloy material mainly composed of iron. 14. A hermetic compressor comprising a closed container, a compression unit accommodated in the closed container, an electric unit, and a crank mechanism for transmitting the rotational force of the electric unit to the compression unit, The compression unit has a cylinder and a piston reciprocating in the cylinder, The crank mechanism has a connecting rod connected to the piston, The ball provided on the connecting rod and the ball receiving hole provided on the piston are freely rotatable and slidably jointed by the earth, and the sliding part of the ball joint is supplied with lubricating oil, and it is characterized in that, The ball symmetrically has a pair of flat faces formed along the length direction of the link, The ball receiving hole has a pair of insertion cutouts formed to be equal to or slightly larger than the thickness between the two flat surfaces, The ball inserted into the ball receiving hole is rotated so that the flat surface enters the insertion cutout to form a ball joint detachment prevention, The piston has a pair of substantially semicircular holding recesses on the outside of the pair of insertion cutouts, a backstop that prevents the ball inserted into the ball receiving hole from rotating in a direction of falling out, The backstop has a pair of embedded legs inserted into the pair of holding recesses and a connecting portion straddling the pair of embedded legs, One of the piston and the connecting rod is an alloy material mainly composed of iron, The hardness of the other material is 1.5 times or more in Vickers hardness with respect to the hardness of the surface layer of the alloy material mainly composed of iron. 15. The hermetic compressor according to claim 14, characterized in that, The pair of fitting legs includes a flat plate portion and two arc portions bent outward from both ends of the flat plate portion and extending close to each other while drawing arcs. 16. The hermetic compressor of claim 15, wherein: The insertion leg has a recessed portion provided inwardly at the center of the flat plate portion and joined to the flat surface of the ball. 17. The hermetic compressor of claim 14, wherein: The connecting portion of the backstop has locking claws that are locked with locking grooves provided on the piston. 18. The hermetic compressor of claim 14, wherein: The backstop is formed from a metal plate including steel plate. 19. A hermetic compressor comprising a closed container, a compression unit accommodated in the closed container, an electric unit, and a crank mechanism for transmitting the rotational force of the electric unit to the compression unit, The compression unit has a cylinder and a piston reciprocating in the cylinder, The crank mechanism has a connecting rod connected to the piston, The ball provided on the connecting rod and the ball receiving hole provided on the piston are freely rotatable and slidably jointed by the earth, and the sliding part of the ball joint is supplied with lubricating oil, and it is characterized in that, the connecting rod has a crankshaft bearing disposed on the opposite side of the ball, The crank mechanism has a crankshaft provided on one side of the electric unit and a crankshaft bearing provided on the end of the connecting rod on the opposite side of the ball to rotatably support the crankshaft, The crankshaft bearing has an annular oil groove on the sliding surface, The connecting rod has an oil supply hole communicating from the oil groove to the side of the sliding portion of the ball, One of the piston and the connecting rod is an alloy material mainly composed of iron, The hardness of the other material is 1.5 times or more in Vickers hardness with respect to the hardness of the surface layer of the alloy material mainly composed of iron. 20. A hermetic compressor comprising a closed container, a compression unit accommodated in the closed container, an electric unit, and a crank mechanism for transmitting the rotational force of the electric unit to the compression unit, The compression unit has a cylinder and a piston reciprocating in the cylinder, The crank mechanism has a connecting rod connected to the piston, The ball provided on the connecting rod and the ball receiving hole provided on the piston are freely rotatable and slidably jointed by the earth, and the sliding part of the ball joint is supplied with lubricating oil, and it is characterized in that, The ball receiving hole has an oil reservoir at its bottom One of the piston and the connecting rod is an alloy material mainly composed of iron, The hardness of the other material is 1.5 times or more in Vickers hardness with respect to the hardness of the surface layer of the alloy material mainly composed of iron.

Images