JP7010786B2 - Compressor - Google Patents

Description

The present invention relates to a compressor.

The compressor of Patent Document 1 is set so that the annular lubrication groove 23e recessed in the piston is exposed from the notch 7c at the bottom dead center of the piston, so that the compressor dies during the suction process. Lubricating oil is supplied from the notch to the lubrication groove, and an oil film is formed between the lubrication groove and the cylinder bore to improve the sealing performance during compression (0025, FIG. 3).

Japanese Unexamined Patent Publication No. 2006-283770

Since the pressure from the compressed refrigerant is applied to the oil film, the piston during compression receives the reaction force from the oil film. However, in the compressor of Patent Document 1, only the upper part of the oil supply groove 23e of the piston is notched at the bottom dead center. It is exposed through the portion 7c, and the other portions are inserted into the cylinder bore. Therefore, after shifting from the suction step to the compression step, the oil film is not formed in the notch portion until the entire circumference of the oil supply groove enters the cylinder bore by moving toward the top dead center. Then, the reaction force of the oil film applied to the piston becomes an imbalance in which the upper side of the piston is small and the lower side is large, and the combined force of the reaction force acts in the direction of swinging the piston in the vertical direction.

The vertical runout of the piston increases the vibration of the entire compressor, leading to an increase in noise. Further, when the runout becomes excessive, wear may occur between each member such as the piston and the cylinder bore, the connecting rod for transmitting the driving force to the piston, the piston pin, and the shaft. Abrasion causes heat loss, which causes deterioration of compressor performance and may impair the reliability of the compressor.

The present invention made in view of the above circumstances is
A cylinder with a cylinder bore provided with a cylindrical void,
A piston that reciprocates in the gap is provided.
A compressor in which lubricating oil is supplied between the cylinder bore and the piston.
The cylinder bore is characterized by having a first notch and a second notch facing each other across the gap.

The vertical sectional view of 1 closed type electric compressor of Example 1. FIG. FIG. 3 is a cross-sectional view of a main part when the piston of the first embodiment is located near the bottom dead center of the compression process. FIG. 2 is a schematic view showing the oil film reaction force applied to the piston during compression in the AA cross-sectional view of FIG. FIG. 6 is a schematic cross-sectional view of a main part showing the relationship between the position of the cylinder bore notch and the oil film at the position near the bottom dead center of the piston of the first embodiment. As a comparative example, a cross-sectional view of a main part when a piston having no lower notch is located near the bottom dead center of the compression process. Schematic diagram showing the oil film reaction force applied to the piston during compression for the A'-A'cross section of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The downward direction in this embodiment may be the same as the direction of gravitational acceleration or may be the same as the other directions.

FIG. 1 is a vertical sectional view of the closed electric compressor of the first embodiment. The cylinder block 2 provided in the closed container 1 integrally forms the bearing portion 2a and the cylinder bore 2b, and the piston 3 reciprocates in the cylinder bore 2b to form a compression element. The cylinder bore 2b has a cylindrical void in which the piston 3 slides, and the piston 3 has a substantially cylindrical shape.

An electric element is configured by a stator 4 fixed to a cylinder block 2 and a rotor 5 connected to an electric motor, and power is transmitted to the compression element by rotating a crankshaft 7 fixed to the rotor 5. The crankshaft 7 has a crankpin 7a at a position eccentric from the center of rotation, and the crankpin 7a and the piston 3 are rotatably connected by a conrod 8 and a piston pin 9, and the rotational motion of the crankshaft 7 is transferred to the piston 3. Converts to reciprocating motion.

The upper notch 2c having a substantially U-shape on the upper surface provided on the upper part of the cylinder bore 2b penetrates to the upper wall of the cylinder block 2, and the piston 3 inserted into the cylinder bore 2b and the connecting rod 8 inserted into the crankpin 7a in advance at the time of assembly. Each part is assembled by inserting the piston pin 9 from the upper notch 2c.

The crankshaft 7 has an internal lubrication passage, and uses centrifugal force due to rotation to suck up the lubricating oil stored in the closed container 1 upward, and similarly in the spout at the upper part of the crankpin 7a and in the connecting rod 8. Lubricating oil is supplied from the formed lubrication passage to the compression element.

The tip of the cylinder bore 2b is sealed by a valve plate 6 having a refrigerant inlet and outlet and a valve that regulates the refrigerant flow at each path port, and a lubricating oil is used between the piston 3 and the cylinder bore 2b. It is sealed and the refrigerant flows through the refrigerant path port of the valve plate 6 during suction and compression.

During low-speed rotation, the centrifugal force due to rotation becomes smaller, so the amount of lubricating oil sucked up by the crankshaft 7 becomes smaller, the amount of lubricating oil supplied to the compression element decreases, and the seal between the piston 3 and the cylinder bore 2b becomes smaller. Due to the reduced property, the refrigerant tends to leak during compression. Therefore, it is desired to improve the sealing property.

FIG. 2 is a cross-sectional view of a main part when the piston 3 of this embodiment is located near the bottom dead center of the compression process. FIG. 3 is a sectional view taken along the line AA of FIG. 2, which is a schematic view showing the oil film reaction force applied to the piston 3 during compression.
One or more annular refueling grooves 31 are recessed on the outer periphery of the piston 3 so as to be lined up in the axial direction (reciprocating direction) of the piston 3. The refueling groove 31 is provided at a position different in the axial direction from the position of the center of rotation of the piston 3, the position of the piston pin 9 in this embodiment. In this embodiment, it is provided at a position on the top dead center side of the rotation center position.
The cylinder bore 2b is provided with a cylindrical gap in which the piston 3 reciprocates. The cylinder bore 2b has two notches 2c and 2d facing each other with the center of the gap in the axial direction. When the notch portions 2c and 2d are located on the upper side and the lower side of the cylinder bore 2b, the piston pin 9 can be easily inserted through the upper notch portion 2c, and the lubricating oil supplied from the ejection port can easily reach.

At the bottom dead center where the piston 3 is most pulled out from the cylinder bore 2b, the upper portion of the refueling groove 31 is exposed via the upper notch 2c of the cylinder bore 2b. Further, the lower portion of the oil supply groove 31 is exposed via the lower notch portion 2d of the cylinder bore 2b.

Lubricating oil ejected from the upper part of the crankpin 7a is applied to the upper part of the oil supply groove 31 through the upper notch 2c, and is transmitted to the entire circumference of the oil supply groove 31 to be supplied. Further, when the piston 3 is pushed into the cylinder bore 2b during compression, the lubrication groove 31 completely enters the cylinder bore 2b, and the lubricating oil is held by the inner wall of the cylinder bore 2b and the lubrication groove 31, so that the lubricating oil is held at low speed rotation. Even with a small amount of lubricating oil supplied, high sealing performance between the piston 3 and the cylinder bore 2b can be maintained.

The lubricating oil supplied to the oil supply groove 31 forms an oil film in the gap between the piston 3 and the cylinder bore 2b, and receives the pressure of the compressed refrigerant by the oil film to suppress the leakage of the refrigerant to the low pressure side. That is, during compression, the oil film receives pressure from the compressed refrigerant, which is also transmitted to the piston 3 as an oil film reaction force.

At the bottom dead center, a part of the lubrication groove 31 is exposed from the cylinder bore 2b via the upper notch 2c or the lower notch 2d. When a plurality of lubrication grooves 31 are provided, it is preferable that the upper portions of all the lubrication grooves 31 are exposed from the cylinder bore 2b at the bottom dead center in order to supply the lubricating oil to all the lubrication grooves 31. That is, among the oil supply grooves 31a closest to the top dead center side, it is preferable that the upper portion of the groove end portion 32b on the bottom dead center side is exposed from each of the upper notch portion 2c and the lower notch portion 2d at the bottom dead center. Since the reaction force is generated by the lubricating oil stored in the lubrication groove 31a being sandwiched between the cylinder bore 2b and the piston 3, the compression process is mainly performed at the rear end of the lubrication groove 31 in the moving direction (that is, bottom dead center). It is produced by the lubricating oil present at the end 32b) on the point side.

In this embodiment, the lower notch 2d is provided at a position substantially point-symmetrical to the upper notch 2c around the center of the cylinder bore 2b in the axial view of the piston 3. Therefore, the oil film 10 formed between the piston 3 and the cylinder bore 2b by the lubricating oil stored in the oil supply groove 31 in the compression process near the bottom dead center and the oil film reaction force thereof become substantially symmetrical with respect to the axis center of the piston 3. The overturning moment acting on the piston 3 (the moment that rotates around the center of gravity of the piston in the radial view of the piston 3) can be suppressed. The three-dimensional structure of the piston 3 can be, for example, plane-symmetrical.

The upper notch portion 2c and the lower notch portion 2d can exist at substantially the same position in the axial position of the piston 3, respectively. That is, the length of the refueling groove 31 exposed through the upper notch 2c and the length of the refueling groove 31 exposed through the lower notch 2d can be substantially the same.
Specifically, considering two virtual straight lines passing through the inner peripheral end of the upper notch 2c and the center of the cylinder bore 2b in the axial direction, in the region sandwiched between these two straight lines. , There is a lower notch 2d. It is most preferable that the lower notch portion 2d extends over the entire area within this region and does not exist outside the region, but it is effective even when it is substantially present in only a part of this region.

From the viewpoint of workability, it is considered that the position of the lower notch portion 2d is not completely symmetrical with respect to the upper notch portion 2c. If there is a difference in the axial position between the upper notch 2c and the lower notch 2d, the lubricating oil stored in the oil supply groove 31 when the compression process progresses forms an oil film 10 between the piston 3 and the cylinder bore 2b and the oil film 10 thereof. There may be a moment when the oil film reaction force becomes vertically asymmetric. However, at least, by setting the positional relationship in which the lower portion of the refueling groove 31 is exposed from the lower notch 2d at the bottom dead center, the lubricating oil stored in the refueling groove 31 of the portion exposed from the lower notch 2d flows out from the refueling groove 31. Then, the overturning moment due to the vertical asymmetry of the oil film reaction force can be suppressed until the lubrication groove 31 is filled with the lubricating oil supplied from the upper notch portion 2c again.

Further, the sealing property between the piston 3 and the cylinder bore 2b is required not only at the time of compression but also at the time of suction. By improving the sealing property at the time of suction, the fluid noise of the refrigerant can be suppressed by flowing the refrigerant through an appropriate route, and the density of the refrigerant gas can be increased, which leads to the improvement of performance. Further, if the sealing is insufficient at the time of suction, the lubricating oil enters the cylinder bore 2b together with the leaked refrigerant, and the lubricating oil is mixed in the compressed and discharged refrigerant, which causes a decrease in the cooling power of the refrigeration cycle. ..

FIG. 4 is a cross-sectional view of a main part showing the relationship between the position of the notch portion of the cylinder bore 2b and the oil film 10 in the vicinity of the bottom dead center of the suction step of this embodiment. Since the piston 3 moves toward the bottom dead center during suction, if the end 32 on the top dead center side of the oil supply groove 31 is exposed from the cylinder bore 2b, no reaction force is generated and the piston 3 is located inside the cylinder bore 2b. If so, a reaction force may occur.

In this embodiment, as shown in FIG. 4, of the refueling grooves 31a closest to the top dead center, the end portion 32a on the top dead center side has the upper notch 2c and the lower notch 2d even at the bottom dead center. It is set not to be exposed from. With such a positional relationship, the lubricating oil always stored in the oil supply groove 31a in the suction step forms an oil film between the piston 3 and the cylinder bore 2b, and the sealing property can be maintained.

Since the exposed amount of the lubrication groove 31a in the upper notch 2c affects the supply amount of the lubricating oil to the lubrication groove 31a, when it is prioritized to secure the supply amount of the lubricating oil, the end portion 32a is the upper notch. It is also conceivable to set it so that it is exposed from 2c. For example, by providing a long axial dimension of the lubrication groove 31a, the end portion 32a is located in the cylinder bore 2b while the other portion of the lubrication groove 31a is formed. It is also possible to expose it.

On the other hand, since the lubricating oil stored in the oil supply groove 31 flows downward through the groove 31, when the refrigerant leaks from the lower notch 2d because the seal by the oil film cannot be maintained, it enters the cylinder bore 2b together with the refrigerant. Since the amount of lubricating oil that leaks in is also large, preventing the end portion 32a from coming out of the lower notch portion 2d has a great effect of suppressing the amount of lubricating oil mixed in the discharged refrigerant.

Comparative example

As a comparative example, FIG. 5 is a cross-sectional view of a main part when the piston 3 having no lower notch 2d is located near the bottom dead center of the compression process, and FIG. 6 is a compression view of the A'-A'cross section of FIG. It is a schematic diagram which showed the oil film reaction force sometimes applied to a piston 3.

In the case of the comparative example, in the compression step near the bottom dead center, the oil supply groove 31 is only exposed from the cylinder bore 2b on the upper notch 2c side, so that the oil film 10 covers the entire circumference except the upper notch 2c. Is formed in.

Then, since the oil film reaction force applied to the piston 3 is generated asymmetrically as shown in FIG. 6, the combined force of the oil film reaction force acts to rotate the piston 3 in the radial direction and rotates it with respect to the axis of the piston 3. Overturning moment is applied.

Since the oil film reaction force and the overturning moment become larger at high speed rotation, it becomes a bigger problem when the compressor has a high maximum rotation speed as a product specification.

1 Closed container 2 Cylinder block 2a Bearing part 2b Cylinder bore 2c Upper notch part (1st notch part)
2d lower notch (second notch)
3 Piston 4 Stator 5 Rotor 6 Valve plate 7 Crankshaft 7a Crankpin 8 Conrod 9 Piston pin 10 Oil film 31 Refueling groove 31a Refueling groove closest to top dead center 32a Refueling groove closest to top dead center on the top dead center side End 32b The end of the refueling groove closest to the top dead center on the bottom dead center side

Claims (4)

A cylinder with a cylinder bore provided with a cylindrical void,
A piston that reciprocates in the gap is provided.
A compressor in which lubricating oil is supplied between the cylinder bore and the piston.
The cylinder bore has a first notch and a second notch facing each other across the gap .
The piston has an annular refueling groove and has an annular refueling groove.
At the bottom dead center of the piston, the refueling groove
A portion exposed from the cylinder bore through the first notch, and a portion exposed from the cylinder bore.
A portion exposed from the cylinder bore through the second notch, and a portion exposed from the cylinder bore.
It has a portion facing the cylinder bore and
Of the refueling groove exposed through the first notch or the second notch.
The end on the top dead center side of the portion located on the first notch side in the circumferential direction is located on the top dead center side of the first notch at the bottom dead center of the piston, and / or. ,
The end portion on the top dead center side of the portion located on the second notch side in the circumferential direction is characterized in that it is located on the top dead center side of the second notch portion at the bottom dead center of the piston. Compressor. The compressor according to claim 1, wherein either one of the first notch and the second notch is located on the side opposite to the direction of gravitational acceleration with respect to the void. In a cross-sectional view of the piston in the reciprocating direction, one of the second notches is located in a region sandwiched by two virtual straight lines substantially passing through the end of the first notch and the center of the gap. The compressor according to claim 1 or 2 , wherein the unit fits. In a cross-sectional view in the reciprocating direction of the piston, the entire second notch portion is located in a region sandwiched by two virtual straight lines substantially passing through each of the end portion of the first notch portion and the center of the gap. The compressor according to claim 1 or 2 , wherein the compressor fits in the compressor.

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