JPH0968165A - Reciprocation compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance reliability and prevent noise of low frequency range from occurring by preventing bias in a bearing caused by a crankshaft. SOLUTION: A crankshaft 6 is supported in a closed vessel by a main bearing 7a of a slip bearing integrally formed with a frame 7 and an auxiliary bearing 19 composed of the same slip bearing as the main bearing 7a. An eccentric part 6a is formed on the upper part of the crankshaft 6 and a compressing element part 3 compresses refrigerant gas by means of the eccentric rotation. A motor part 2 is placed between the main bearing 7a and the auxiliary bearing 19 so as to make the crankshaft 6 rotational. The auxiliary bearing 19 is formed annually and an inner surface 19a thereof has a curved surface like an inner surface of a torus, for instance, and is able to support the crankshaft 6 slidiably by this structure. By the inner surface 19a, the auxiliary bearing 19 has a self aligning function to support the crankshaft 6 even if the crankshaft 6 is inclined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating compressor suitable for use in refrigerators, room air conditioners, etc., and more particularly to a reciprocating compressor capable of improving reliability and reducing noise. Regarding

[0002]

2. Description of the Related Art FIG. 6 is a vertical sectional view showing an example of a conventional reciprocating compressor, in which 1 is a hermetic container, 2 is an electric motor part, and 2a.
Is a stator, 2b is a stator, 3 is a compression element portion, 4 is a spring,
5 is a lubricating oil, 6 is a crankshaft, 6a is an eccentric part, 6c is a vertical hole, 7 is a frame, 7a is a main bearing, 8 is a piston, 9 is a slider, 10 is a cylinder, 11 is a suction valve, and 12 is a valve seat plate. , 13 is a discharge valve, 14 is a cover body, 14a is a discharge chamber, 15 is a discharge pipe, and 17 is a compression chamber.

In FIG. 1, an electric motor unit 2 is provided in a closed container 1.
The compression element 3 and the compression element 3 are connected by a crankshaft 6 and arranged and housed in the vertical direction, and elastically supported by the closed container 1 via a spring 4. The crankshaft 6 is provided integrally with the frame 7 on the inner diameter side of the frame 7, and the inner diameter surface is supported by a main bearing 7a which is a sliding bearing similar to the inner diameter surface of a cylinder.

The compression element 3 is of a reciprocating type called a Scotch-yoke type, and a slider 9 fitted to an eccentric portion 6a formed at the upper end of the crankshaft 6 reciprocally moves integrally. A piston 8 that is included, a cylinder 10 that reciprocates the piston 8, a suction valve 11, a valve seat plate 12, and a discharge valve 13 that are sequentially provided on an end surface of the cylinder 10, a compression chamber 17 and a discharge valve 13 inside the cylinder 10. Discharge chamber 14 formed by a cover body 14 communicating with each other through
a and a discharge pipe 15 extending from the discharge chamber 14a to the outside of the closed container 1.

Lubricating oil 5 is stored in the bottom of the closed container 1, and when the crankshaft 6 rotates, the centrifugal force causes the lubricating oil 5 to go into a vertical hole 6c provided inside the crankshaft 6.
It is sucked up through and is supplied to the main bearing 7a, the eccentric portion 6a, and the like, and is also sprayed from the upper opening of the eccentric portion 6a to the upper space thereof and is supplied to the outer diameter of the piston 8 and the like. In this way, each part is refueled.

The electric motor section 2 is composed of a stator 2a and a rotor 2b, and the stator 2a is fixed to a frame 7, and the rotor 2
b is shrink-fitted to the crankshaft 6.

When the crankshaft 6 is rotated by the electric motor unit 2, the piston 8 reciprocates laterally in the cylinder 10 and moves rightward in the drawing to move the compression chamber 1 in the cylinder 10 to the right.
When the volume of 7 increases, the inside of the compression chamber 17 becomes negative pressure and the suction valve 11 opens. The closed casing 1 is filled with a refrigerant gas from a suction pipe (not shown), and when the suction valve 11 is opened, the refrigerant gas inside the closed container 1 is sucked into the compression chamber 17.

Next, when the piston 8 reaches the bottom dead center and shifts to the left in the drawing, the suction valve 11 closes and the compression chamber 1
The volume of 7 decreases and the pressure of the refrigerant gas rises. When the pressure of the refrigerant gas reaches the discharge pressure, the discharge valve 13 opens, and the refrigerant gas is discharged into the discharge chamber 14a until the piston 8 reaches the top dead center. The discharged refrigerant gas is guided to the outside of the closed container 1 through the discharge pipe 15.

The above-described steps of sucking, compressing and discharging the refrigerant gas are repeated by the rotation of the crankshaft 6.

In the refrigerator using the reciprocating compressor as described above, a CFC12 or other CFC has been used as a refrigerant for the refrigeration cycle. However, due to the problem of ozone layer depletion, a CFC or HCFC refrigerant containing a chlorine element. Its use is being regulated, and alternative refrigerants such as HFC that do not contain chlorine elements that destroy the ozone layer are being studied.

[0011]

By the way, in the above-described operation, the differential pressure between the pressure in the compression chamber 17 and the suction pressure in the closed container 1 is applied to the piston 8 to cause the cylinder 10 to move.
It is considered that a concentrated load F acts in the moving direction of the viston 8 inside, and this load acts on the eccentric portion 6a of the crankshaft 6 via the slider 9 and the main bearing via the journal portion of the crankshaft 6. It acts on 7a. When the suction pressure is considered to be almost constant, this concentrated load increases in proportion to the increase in pressure in the compression chamber 17, and changes with respect to the rotation angle of the crankshaft 6 as shown in FIG. When the pressure of the refrigerant gas reaches the discharge pressure K, it becomes the maximum Fmax.

As described above, the compression element portion 3 receives the unilateral load in which the load F changes from almost 0 to Fmax for each rotation of the crankshaft 6, and in the case of the single-phase induction motor, it takes 1 second. It will be subjected to repeated loads approximately the number of times near the power supply frequency. Further, as the pressure in the compression chamber 17 changes, structural members such as the cylinder 10 and the valve seat plate 12 are repeatedly loaded.

In a reciprocating compressor, the crankshaft 6 is generally supported by a cantilever structure having only a main bearing 7a. Therefore, due to the above-mentioned repeated load, the crankshaft 6
Causes eccentric rotation, and abnormal one-sided contact occurs in the main bearing 7a. In particular, when using an alternative refrigerant, in general, due to the difference in physical properties from the conventionally used CFC,
It is necessary to increase the differential pressure between the suction pressure and the discharge pressure and to increase the pushing amount due to the reduction in refrigerating capacity. As a result, the repeated load applied to the members such as the crankshaft 6 and the frame 7 uses the conventional refrigerant. It has become necessary to consider the fatigue fracture strength of the constituent members more than the case.

In addition, the crankshaft 6 may be bent,
Even when the crankshaft 6 is installed so as to be tilted with respect to the main bearing 7a, abnormal one-sided contact similarly occurs in the main bearing 7a.

As an example of dealing with such an increase in applied load, there is a countermeasure against fatigue fracture strength by improving the material.
That is, as the material used for the compression element portion, gray cast iron is often used, but as an improvement of the material in that case, it is a spheroidal graphite cast iron obtained by spheroidizing the flake graphite in the gray cast iron, and the notch effect is small. It is known that the strength can be improved. However, in this case, the hardness becomes high and the workability is significantly deteriorated. Further, in order to make the graphite spherical, it is necessary to strictly control the manufacturing process such as adding cerium or magnesium.

Incidentally, there are problems such as the occurrence of intergranular cracks as disclosed in JP-A-5-71488, and there is a limit to the choice of surface treatment even after improvement.

Further, when the material is changed to a steel type, there is a case where the structure is greatly changed due to the compatibility with the mating material, and similarly, there is a problem that productivity is lowered.

Furthermore, since the support of the crankshaft 6 is a cantilever structure, the shaft system natural frequency of the compression element portion 3 is 200.
There is a peak at ~ 800 Hz. Further, low frequency sound of 1000 Hz or less is increased due to resonance with electromagnetic vibration generated at an even multiple of the power supply frequency.

An object of the present invention is to provide a reciprocating compressor which solves such a problem, can cope with an increase in load with a simple structure, and can reduce noise. Especially.

[0020]

In order to achieve the above object, the present invention provides a slide bearing as a sub bearing for supporting the crankshaft on the side opposite to the compression element part with respect to the electric motor part, and the outside of the crankshaft is provided. A self-centering function is provided on the inner diameter surface of the slide bearing with which the diameter surface is in contact.

Further, according to the present invention, a slide bearing for supporting the crankshaft is provided on the side opposite to the compression element portion with respect to the electric motor portion, and the slide bearing has a first inner diameter surface in contact with an outer diameter surface of the crankshaft. The bearing member and the second bearing member, which is in contact with the inner diameter surface of the outer diameter surface of the first bearing member and maintains the self-centering function.

Further, according to the present invention, the material of the above sliding bearing is a sintered alloy or a resin material which can be molded.

[0023]

The sub-bearing that supports the lower end of the crankshaft (that is, the sliding bearing) has a self-aligning function, so that the center axis of the sub-bearing is aligned with the center axis of the crankshaft that supports the crankshaft. Take action. Therefore, the crankshaft can take any posture in the sub bearing. Therefore, even if the crankshaft is inclined and assembled, or the crankshaft is deformed during operation, the abnormal centering can be prevented by the self-aligning function.

Further, since the auxiliary bearing is provided, the natural frequency of the compression element portion moves to the high frequency side and moves away from the power supply frequency. As a result, the influence of resonance with electromagnetic vibration and the like is reduced, so that low-frequency sound of 1000 Hz or less can be reduced.

Furthermore, by using a sintered alloy or a resin material that can be used for molding the auxiliary bearing, it is possible to omit high-precision finishing.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a first embodiment of a reciprocating compressor according to the present invention, in which 19 is a sub bearing, 19a is an inner diameter surface, and 20 is a bearing support. The same reference numerals are given and duplicate description is omitted.

In the figure, the vicinity of the lower end of the crankshaft 6 on the opposite side of the electric motor section 2 from the compression element section 3 (opposite compression element section side) is supported by an auxiliary bearing 19 which is a slide bearing. That is, the crankshaft 6 is supported by the main bearing portion 7 a and the sub bearing 19 which are integrated with the frame 7. The sub bearing 19 is attached to the bearing support 20.

The bearing support 20 is a plan view of the bearing support 20 as seen from the side of the electric motor section 2 and is shown in FIG. 2 (a) and section line A in FIG. 2 (a).
As is apparent from FIG. 2B, which is a vertical cross-sectional view (that is, a cross-sectional view similar to FIG. 1) viewed from -A, it projects inward at four corners of the upper end of the wall portion 20a having a substantially rectangular tubular shape. A planar mounting portion 20c is formed, and a plate-shaped holding portion 20d is formed by projecting inward from the lower four sides of the wall portion 20a. These four holding portions 20d form a central portion of the wall portion 20a. Has a structure in which the bearing support portion 20b is held.

Here, the bearing support portion 20b is shown in FIG.
When viewed from below, it has a recessed shape toward the inside of the wall portion 20a, and the flat bearing mounting portion 20e is in the recessed portion.
Is formed and the auxiliary bearing 19 is attached thereto. Further, the crankshaft 6 is provided at the center of the bearing mounting portion 20e.
Slightly larger than the diameter of (Fig. 1) and the auxiliary bearing 19
Crankshaft penetration hole 2 with a diameter smaller than the outer shape of (Fig. 1)
0f is provided.

The bearing support 20 in which the auxiliary bearing 19 is attached to the bearing attachment portion 20e has the attachment portion 20c attached to the lower surface portion of the stator 2a of the electric motor portion 2 so that the electric motor portion 2 can be formed as shown in FIG. Is fixed to the bearing support portion 20b.
The crankshaft 6 penetrates through the crankshaft penetration hole 20f and is supported by the auxiliary bearing 19.

As described above, since the crankshaft 6 is supported by the bearing portion 7a of the frame 7 and the auxiliary bearing 19, the cylinder 1
Even if the above-mentioned repeated load is applied to the crankshaft 6 by the operation of 0, the eccentric rotation of the crankshaft 6 can be suppressed, and the abnormal partial contact of the crankshaft 6 with the bearing portion 7a of the frame 7 does not occur. .

The inner diameter surface 19a of the auxiliary bearing 19 which is in contact with the outer diameter surface of the crankshaft 6 has the same shape as the inner diameter surface of the torus (a toroidal annular body), that is, the centerline of the crankshaft 6. The cross-sectional shape on an arbitrary plane is an arc shape protruding toward the crankshaft 6 side.

Therefore, the posture of the portion of the crankshaft 6 supported by the auxiliary bearing 19 is not uniquely regulated like the portion supported by the cylindrical bearing, but to some extent. Is the degree of freedom. That is, the crankshaft 6
Even if the center axis of the sub-bearing is tilted with respect to the center axis of the sub-bearing 19, the sub-bearing 19 has a self-centering function of normally supporting the crankshaft 6 even when the crankshaft 6 is rotated.

Due to the self-centering function, the crankshaft 6 is mounted in a tilted state in the assembly of the compressor (of course, this tilt is slight), and even if the crankshaft 6 is rotated in such a state, the auxiliary bearing 19 is locked in the crank. The shaft 6 can be normally supported, and even if the rotating crankshaft 6 has a flexure (of course, this flexure is slight), it can be similarly supported. For this reason, the accuracy with respect to the deflection of the crankshaft 6 and the mounting posture is relaxed, and the compressor is easily assembled. In addition, in the sub bearing 19, there is no partial contact of the crankshaft 6.

As described above, in this embodiment, it is possible to prevent the bearing portion 7a of the frame 7 having a cylindrical shape from partially hitting the crankshaft 6, and the auxiliary bearing irrespective of the posture of the crankshaft 6. The crankshaft 6 can be supported by 19, and the reliability and the assemblability can be improved.

The material of the sub bearing 19 is a sintered alloy or a resin material which can be molded. As a result, the secondary bearing 19 does not require high-precision finishing, so that the cost can be reduced.

Further, the natural frequency of the compression element portion 3 moves to the high frequency side and becomes far from the frequency of the power source due to the provision of the sub bearing 19. As a result, the influence of resonance with electromagnetic vibration is reduced, and low-frequency sound of 1000 Hz or less is reduced.

FIG. 3 is a diagram showing such an effect, showing the attenuation characteristic of the sound pressure level which is reduced by providing the auxiliary bearing 19 on the vertical axis and the measured frequency indicated by 1/3 octave on the horizontal axis. ing.

In the figure, 800 Hz and 1000 Hz
Is slightly increased, but at 630 Hz or less, a remarkable noise reduction damping characteristic is exhibited, and the effect of installing the auxiliary bearing 19 is exhibited.

The auxiliary shaft support 20 is made of a steel plate and is formed by high-precision cold plastic working of a steel plate, and can be formed in a short time.

The attachment of the auxiliary shaft support 20 to the stator 2a of the electric motor unit 2 is performed by tightening the coil of the stator 2a of the electric motor unit 2 when the stator 2a of the electric motor unit 2 is fastened to the frame 7 with bolts. Since they are fixed together so as to be wrapped, and in this case, the flat mounting portion 20c that abuts with a large area is provided, it is easy to mount in a stable state.

The sub bearing 19 is attached to the sub bearing portion of the crankshaft 6, and is attached to the bearing attaching portion 20e of the sub shaft supporting portion 20b. Thereafter, the constituent members of the sub bearing 19 are centered, and the sub bearing 19 is fixed to the bearing mounting portion 20e by welding or bolts.

In the first embodiment, the sub bearing 19
The inner diameter surface 19a of the torus is the same as the outer diameter surface of the torus, but the invention is not limited to this. The inner diameter surface 19a is a curved surface along the longitudinal direction of the crankshaft 6 and is located at the axial center of the crankshaft. It may be any curved surface that is convex toward the surface. Further, even if the whole is not a curved surface, only the portion in contact with the crankshaft 6 may be curved and the other portions may be flat. FIG. 4 shows two examples.

FIG. 5 is a vertical sectional view showing a second embodiment of the reciprocating compressor according to the present invention, in which 19 'is an auxiliary bearing, and the portions corresponding to those in FIG. The description will be omitted.

In the figure, the auxiliary bearing 19 'has a double structure and has a surface for supporting the crankshaft 6 and a surface for performing the self-centering function. The other points are similar to those of the first embodiment shown in FIG.

FIG. 6 is a longitudinal sectional view showing the structure of the auxiliary bearing 19 and its two states. 6c is the center line of the crankshaft 6, 19'a and 19'b are bearing members, and 19'a1. Is the inner diameter surface of the bearing member 19'a, and 19'a2 is the bearing member 1
9'a is the outer diameter surface, 19'b1 is the inner diameter surface of the bearing member 19'b, and 19'c is the center line of the bearing member 19'b.
Are assigned the same reference numerals.

In the figure, the sub-bearing 19 'has a double structure in which the bearing member 19'a is arranged on the inner diameter side and the bearing member 19'b is arranged on the inner diameter side. The surface 19′a1 forms a cylindrical inner surface to support the crankshaft 6, and the outer diameter surface 19′a2 forms an outer diameter surface of the torus. Further, the inner diameter surface 19′b1 of the bearing member 19b forms the inner diameter surface of the torus, and this inner diameter surface 19′b1
And the outer diameter surface 19'a2 of the bearing member 19'a have the same curvature and are slidably in contact with each other.

The sub-bearing 19 'is the outer bearing member 1
Up to 9'b is supported by the bearing support portion 20b of the bearing support 20, and even if the state of the bearing member 19'a changes with respect to the bearing member 19'b, the bearing member 19'a supports the bearing. The portion 20b is prevented from hitting.

FIG. 6 (a) shows the state of the sub bearing 19 'when the center line 6c of the crankshaft 6 is aligned with the center line 19'c of the bearing member 19'b. The bearing member 19'a is kept horizontal. The crankshaft 6 rotates by sliding on the inner diameter surface 19'a1 of the bearing member 19'a.

In FIG. 6B, the crankshaft 6 is the bearing member 1.
9'a shows a state in which the central axis 19'c of 9'a is tilted by θ, and in this case, the bearing member 19 '
a is inclined with respect to the bearing member 19′b by the same angle. That is, the outer diameter surface 19′a of the bearing member 19′a that is in contact with each other
2 and the inner peripheral surface 19′b1 of the bearing member 19′b have a self-centering function so that the inner diameter surface 19′a1 of the bearing member 19′a is always parallel to the crankshaft 6. When the crankshaft 6 tilts, the bearing member 19'a tilts with respect to the sub bearing 19'b by the tilt angle.

Thus, also in this embodiment,
The crankshaft 6 can freely change its posture in the sub bearing 19 ', and as with the first embodiment shown in FIG. 1, the assemblability can be improved, and the reliability and noise can be improved. An excellent effect of reduction of

[0052]

As described above, according to the present invention,
Since both ends of the crankshaft are supported by two bearings, even if a repetitive load is applied to the crankshaft by the operation of the compression element part, it is possible to prevent the bearing parts from being unbalanced on the crankshaft. The inclination of the crankshaft during assembly is absorbed to improve the accuracy of coaxiality, and the bending of the lower end of the crankshaft 6 during operation is also absorbed to prevent uneven contact of the crankshaft, thus improving reliability. An excellent effect of reducing noise can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a first embodiment of a reciprocating compressor according to the present invention.

FIG. 2 is a diagram showing details of a bearing support in FIG.

FIG. 3 is a characteristic diagram showing an effect of the embodiment shown in FIG.

FIG. 4 is a cross-sectional view showing another specific example of the sub bearing in FIG.

FIG. 5 is a vertical cross-sectional view showing a second embodiment of the reciprocating compressor according to the present invention.

6 is a diagram showing an example of a state in which the sub bearing in FIG. 5 is in relation to the crankshaft.

FIG. 7 is a vertical sectional view showing an example of a conventional reciprocating compressor.

FIG. 8 is a diagram showing a change in force acting on the piston in FIG.

[Explanation of symbols]

 1 Airtight container 2 Electric motor part 3 Compression element part 4 Spring 5 Lubricating oil 6 Crankshaft 6a Eccentric part 7 Frame 7a Main bearing part 8 Piston 9 Slider 10 Cylinder 11 Suction valve 12 Valve seat plate 13 Discharge valve 14 Cover body 14a Discharge chamber 15 Discharge pipe 17 Compression chamber 19, 19 'Secondary bearing 19a Inner diameter surface 19'a, 19'b Bearing member 19'a1 Inner diameter surface 19'a2 Outer diameter surface 19'b1 Inner diameter surface 20 Secondary shaft support

Claims (9)

[Claims] 1. A reciprocating motion in which an electric motor section and a compression element are connected to each other by a crankshaft in a closed container, and the electric motor section and the compression element are elastically supported by a compression coil spring. In the compressor, a slide bearing that supports a crankshaft is provided on the side opposite to the compression element with respect to the electric motor section, and the slide bearing has an inner diameter surface that contacts the outer diameter surface of the crankshaft and maintains a self-centering function. A reciprocating compressor having: 2. The reciprocating compressor according to claim 1, wherein an inner diameter surface of the slide bearing has substantially the same shape as an inner diameter surface of a torus. 3. The smooth surface according to claim 1, wherein the inner surface of the plain bearing has an arbitrary planar cross-sectional shape including the center line of the crankshaft, the smooth projection protruding toward the crankshaft at least at a portion in contact with the crankshaft. A reciprocating compressor characterized by having a simple curved shape. 4. A reciprocating motion in which an electric motor unit and a compression element are connected to each other by a crankshaft in a closed container, and the electric motor unit and the compression element are elastically supported by a compression coil spring. In the compressor, a slide bearing that supports a crankshaft is provided on the side opposite to the compression element with respect to the electric motor section, and the slide bearing includes a first bearing member whose inner diameter surface is in contact with an outer diameter surface of the crankshaft, A reciprocating compressor, comprising: a second bearing member having an inner diameter surface in contact with an outer diameter surface of the first bearing member to maintain a self-centering function. 5. The outer diameter surface of the first bearing member has substantially the same shape as the inner diameter surface of the torus according to claim 4, and the inner diameter surface of the second bearing member in contact therewith has the outer diameter of the torus. A reciprocating compressor characterized by having a shape that is almost the same as the surface. 6. The reciprocating compressor according to claim 1, wherein the material of the slide bearing is a material that can be molded. 7. The reciprocating compressor according to claim 1, wherein the material of the slide bearing is a sintered alloy. 8. The reciprocating compressor according to claim 1, wherein a material of the slide bearing is a resin material. 9. A reciprocating compressor according to any one of claims 1 to 5, wherein a refrigerant compliant with CFC regulation is used.