CN110761976A

CN110761976A - Compressor with a compressor housing having a plurality of compressor blades

Info

Publication number: CN110761976A
Application number: CN201910131027.7A
Authority: CN
Inventors: 铃木遵自; 铃木启爱; 永田修平
Original assignee: Hitachi Global Life Solutions Inc
Current assignee: Meizhi Weiling application parts (Thailand) Co.,Ltd.
Priority date: 2018-07-27
Filing date: 2019-02-20
Publication date: 2020-02-07
Anticipated expiration: 2039-02-20
Also published as: CN110761976B; JP7010786B2; JP2020016203A

Abstract

The invention provides a compressor with excellent reliability. The compressor is provided with: a cylinder tube having a cylinder liner provided with a cylindrical void; and a piston reciprocating in the gap, and supplying lubricating oil between the cylinder liner and the piston, wherein in the compressor, the cylinder liner has a first notch portion and a second notch portion facing each other with the gap therebetween.

Description

Compressor with a compressor housing having a plurality of compressor blades

Technical Field

The present invention relates to a compressor.

Background

In the compressor of patent document 1, the annular oil supply groove 23e provided in a recessed manner in the piston is set in a positional relationship in which it is exposed from the notch portion 7c at the bottom dead center of the piston, so that at the time of the suction step, lubricating oil is supplied from the notch portion to the oil supply groove at the bottom dead center, and an oil film is formed between the oil supply groove and the cylinder liner, thereby improving the sealing performance at the time of compression (paragraph 0025, fig. 3).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2006-283770

Disclosure of Invention

Problems to be solved by the invention

Since the oil film is applied with pressure from the compressed refrigerant, the piston during compression receives a reaction force from the oil film, and in the compressor of patent document 1, only the upper portion of the oil supply groove 23e of the piston is exposed through the notch portion 7c at the bottom dead center, and the other portion enters the cylinder liner. Therefore, after the transition from the suction step to the compression step, an oil film cannot be formed in the notch portion until the oil supply groove enters the cylinder liner over the entire circumference by moving toward the top dead center. Then, the reaction force of the oil film applied to the piston becomes unbalanced in which the upper side of the piston is small and the lower side is large, and the resultant force of the reaction forces acts in a direction in which the piston vibrates in the vertical direction.

The up-and-down vibration of the piston increases the vibration of the entire compressor, resulting in an increase in noise. Further, if the vibration is too large, abrasion of each member such as the piston, the cylinder liner, the link transmitting the operating force to the piston, the piston pin, and the shaft occurs. The wear causes heat loss, which causes a reduction in the performance of the compressor, and also has a problem of deteriorating the reliability of the compressor.

Means for solving the problems

In view of the above circumstances, the present invention is a compressor including: a cylinder tube having a cylinder liner provided with a cylindrical void; and a piston reciprocating in the gap, and supplying lubricating oil between the cylinder liner and the piston, wherein the cylinder liner has a first notch portion and a second notch portion facing each other with the gap therebetween.

Drawings

Fig. 1 is a longitudinal sectional view of a hermetic motor compressor of embodiment 1.

Fig. 2 is a main part sectional view of the piston of embodiment 1 at a position near the bottom dead center of the compression step.

Fig. 3 is a schematic diagram showing an oil film reaction force applied to the piston at the time of compression in the section a-a of fig. 2.

Fig. 4 is a schematic cross-sectional view of a main portion showing a relationship between a position of a cylinder bore notch portion and an oil film when the piston of example 1 is at a position near the bottom dead center in the suction step.

Fig. 5 is a main part sectional view of a piston having no undercut portion as a comparative example at a position near the bottom dead center in the compression step.

Fig. 6 is a schematic diagram showing an oil film reaction force acting on the piston at the time of compression with respect to the section a '-a' of fig. 5.

Description of the symbols

1-a closed container, 2-a cylinder block, 2 a-a bearing portion, 2 b-a cylinder liner, 2 c-an upper notch portion (first notch portion), 2 d-a lower notch portion (second notch portion), 3-a piston, 4-a stator, 5-a rotor, 6-a valve plate, 7-a crankshaft, 7 a-a crank pin, 8-a link rod, 9-a piston pin, 10-an oil film, 31-an oil supply groove, 31 a-an oil supply groove closest to an upper dead center, 32 a-an end portion on a side of the upper dead center in the oil supply groove closest to the upper dead center, and 32 b-an end portion on a side of the lower dead center in the oil supply groove closest to the upper dead center.

Detailed Description

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

[ example 1 ]

Fig. 1 is a longitudinal sectional view of the hermetic motor compressor of embodiment 1. A bearing portion 2a and a cylinder liner 2b are integrally formed in a cylinder block 2 provided in the closed casing 1, and a piston 3 reciprocates in the cylinder liner 2b to constitute a compression element. The cylinder liner 2b has a cylindrical gap in which the piston 3 slides, and the piston 3 has a substantially cylindrical shape.

The stator 4 fixed to the cylinder block 2 and the rotor 5 connected to the motor constitute an electric element, and power is transmitted to the compression element by rotating a crankshaft 7 fixed to the rotor 5. The crankshaft 7 has a crank pin 7a at a position offset from the rotation center, and the crank pin 7a and the piston 3 are rotatably connected by a link 8 and a piston pin 9, and the rotational motion of the crankshaft 7 is converted into the reciprocating motion of the piston 3.

An upper notch 2c provided in an upper portion of the cylinder liner 2b and having a substantially U-shape in plan view penetrates the upper wall of the cylinder block 2, and when assembling, the piston pin 9 is inserted from the upper notch 2c into the piston 3 inserted in the cylinder liner 2b in advance and the link 8 inserted into the crank pin 7a, and the respective members are assembled.

The crankshaft 7 has an oil supply passage therein, draws up the lubricant oil accumulated in the closed casing 1 upward by centrifugal force of rotation, and supplies the lubricant oil to the compression element from an outlet port at the upper portion of the crankpin 7a and the oil supply passage similarly formed in the link 8.

The cylinder liner 2b has a suction port and a discharge port for refrigerant and valves for regulating the flow of refrigerant at the respective passage ports at the tip thereof, and is closed by a valve plate 6, and the piston 3 and the cylinder liner 2b are sealed by lubricating oil, so that refrigerant flows through the refrigerant passage ports of the valve plate 6 during suction and compression of refrigerant.

When the engine rotates at a low speed, the centrifugal force of the rotation is small, so that the amount of lubricant drawn by the crankshaft 7 is small, the amount of lubricant supplied to the compression element is reduced, the sealing performance between the piston 3 and the cylinder liner 2b is reduced, and the refrigerant is likely to leak during compression. Therefore, improvement in sealing property is desired.

Fig. 2 is a main portion sectional view of the piston 3 of the present embodiment at a position near the bottom dead center of the compression step. Fig. 3 is a schematic view showing an oil film reaction force applied to the piston 3 at the time of compression in the section a-a of fig. 2. One or more annular oil supply grooves 31 are provided in the outer periphery of the piston 3 so as to be aligned and recessed in the axial direction (reciprocating direction) of the piston 3. The oil supply groove 31 is provided at another position in the axial direction with respect to the rotation center position of the piston 3, i.e., the position of the piston pin 9 in the present embodiment. In the present embodiment, the rotation center position is set closer to the top dead center side than the rotation center position.

The cylinder liner 2b is provided with a cylindrical gap through which the piston 3 reciprocates. The cylinder liner 2b has two

cutout portions

2c and 2d facing each other with the center of the gap therebetween in an axial view. The

cutout portions

2c and 2d are preferably located above and below the cylinder liner 2b, because the piston pin 9 can be easily inserted through the cutout portion 2c on the upper side, and the lubricating oil supplied from the discharge port can be easily reached.

At the bottom dead center where the piston 3 is maximally drawn out from the cylinder liner 2b, the upper portion of the oil supply groove 31 is exposed through the upper cutout portion 2c of the cylinder liner 2 b. Further, the lower portion of the oil supply groove 31 is exposed through the lower cutout portion 2d of the cylinder liner 2 b.

The lubricant oil discharged from the upper portion of the crank pin 7a is supplied to the upper portion of the oil supply groove 31 through the upper cutout portion 2c, and is transferred and supplied to the oil supply groove 31 over the entire circumference. Further, when the piston 3 is pushed into the cylinder liner 2b during compression, the oil supply groove 31 completely enters the cylinder liner 2b, and the lubricating oil is retained by the inner wall of the cylinder liner 2b and the oil supply groove 31, whereby the sealing property between the piston 3 and the cylinder liner 2b can be maintained high even at a small amount of lubricating oil supplied during low-speed rotation.

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

At the bottom dead center, a part of the oil supply groove 31 is exposed from the cylinder liner 2b via the upper cutout portion 2c or the lower cutout portion 2 d. When a plurality of oil supply grooves 31 are provided, it is preferable that all the oil supply grooves 31 be exposed from the cylinder liner 2b at the top of the bottom dead center in order to supply the lubricating oil to all the oil supply grooves 31. That is, the upper portion of the bottom-dead-center-side groove end portion 32b in the oil supply groove 31a near the top dead center is preferably exposed from the upper cutout portion 2c and the lower cutout portion 2d at the bottom dead center. The reaction force is generated by the lubricating oil that has accumulated in the oil supply groove 31a being sandwiched between the cylinder liner 2b and the piston 3, and therefore, is mainly generated by the lubricating oil that is present at the rear end (i.e., the end portion 32b on the bottom dead center side) in the oil supply groove 31 in the moving direction in the compression step.

In the present embodiment, the lower cutout portion 2d is provided at a position substantially point-symmetrical to the upper cutout portion 2c around the center of the cylinder liner 2b in the axial view of the piston 3. Therefore, the oil film 10 formed between the piston 3 and the cylinder liner 2b by the lubricating oil accumulated in the oil supply groove 31 in the compression step near the bottom dead center and the reaction force of the oil film are substantially symmetrical with respect to the axial center of the piston 3, and the overturning moment acting on the piston 3 (the moment rotating around the center of gravity of the piston in the radial direction of the piston 3) can be suppressed. The three-dimensional structure of the piston 3 can be, for example, plane-symmetrical.

The upper cutout portion 2c and the lower cutout portion 2d can be located at substantially the same position in the axial direction of the piston 3. That is, the length of the oil supply groove 31 exposed through the upper cutout portion 2c and the length of the oil supply groove 31 exposed through the lower cutout portion 2d can be substantially the same.

Specifically, when two imaginary straight lines passing through the inner peripheral end of the upper cutout portion 2c and the center of the axial visual field of the cylinder liner 2b are considered, the lower cutout portion 2d exists in a region sandwiched by the two straight lines. The lower cutout 2d is most preferably not present outside the area over the entire area in the area, but can be effective even when substantially present only in a part of the area.

From the viewpoint of workability, it is considered that the position of the lower cutout portion 2d is not completely symmetrical with respect to the upper cutout portion 2 c. If there is a difference in the axial positions of the upper cutout portion 2c and the lower cutout portion 2d, there is a possibility that the lubricating oil accumulated in the oil supply groove 31 will be at an instant when the oil film 10 formed between the piston 3 and the cylinder liner 2b and the reaction force of the oil film are vertically asymmetric during the compression step. However, by adopting the positional relationship in which at least the lower portion of the oil supply groove 31 is exposed from the lower cutout portion 2d at the bottom dead center, the lubricating oil accumulated in the oil supply groove 31 at the portion exposed from the lower cutout portion 2d flows out from the oil supply groove 31, and before the oil supply groove 31 is filled again with the lubricating oil supplied from the upper cutout portion 2c, the overturning moment due to the vertical asymmetry of the oil film reaction force can be suppressed.

Further, the sealing property between the piston 3 and the cylinder liner 2b is necessary 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 sound of the refrigerant can be suppressed by flowing the refrigerant through an appropriate path, and in addition, the density of the refrigerant gas can be increased, leading to an improvement in performance. Further, if the sealing is insufficient at the time of suction, the lubricating oil enters the cylinder liner 2b together with the leaked refrigerant, and the lubricating oil is mixed into the refrigerant discharged by compression, which becomes a factor of reducing the cooling power of the refrigeration cycle.

Fig. 4 is a main part cross-sectional view showing the relationship between the oil film 10 and the position of the notch portion of the liner 2b near the bottom dead center in the suction step of the present embodiment. At the time of intake, the piston 3 moves to the bottom dead center side, and when the end portion 32 on the top dead center side in the oil supply groove 31 is exposed from the cylinder liner 2b, a reaction force is not generated, and when the end portion is positioned in the cylinder liner 2b, a reaction force may be generated.

In the present embodiment, as shown in fig. 4, the top dead center side end portion 32a of the oil supply groove 31a closest to the top dead center side is set so as not to be exposed from the upper cutout portion 2c and the lower cutout portion 2d at the bottom dead center. By adopting such a positional relationship, the lubricating oil accumulated in the oil supply groove 31a in the suction step forms an oil film between the piston 3 and the cylinder liner 2b at all times, and the sealing performance can be maintained.

Since the amount of the oil supply groove 31a exposed at the upper cutout portion 2c affects the amount of the lubricant supplied to the oil supply groove 31a, when priority is given to ensuring the amount of the lubricant supplied, it is conceivable that the end portion 32a is set to be exposed from the upper cutout portion 2c, or that the end portion 32a is positioned in the cylinder liner 2b and the other portions of the oil supply groove 31a are exposed by setting the axial dimension of the oil supply groove 31a to be long, for example.

On the other hand, since the lubricating oil accumulated in the oil supply groove 31 flows downward along the groove 31, when the refrigerant leaks due to failure to maintain the oil film seal, the amount of the lubricating oil leaking into the cylinder liner 2b together with the refrigerant increases in the notched portion 2d, and therefore, the effect of preventing the end portion 32a from being exposed to the notched portion 2d is large in suppressing the amount of the lubricating oil mixed into the discharged refrigerant.

[ COMPARATIVE EXAMPLE ]

Fig. 5 is a main portion cross-sectional view of a comparative example in which the piston 3 without the undercut portion 2d is located near the bottom dead center in the compression step, and fig. 6 is a schematic view showing an oil film reaction force applied to the piston 3 during compression with respect to the section a '-a' of fig. 5.

In the case of the comparative example, in the compression step near the bottom dead center, only the oil supply groove 31 is exposed from the liner 2b on the side of the upper cutout portion 2c, and therefore the oil film 10 is formed on the entire circumference except for the upper cutout portion 2 c.

Then, the oil film reaction force applied to the piston 3 is generated asymmetrically as in fig. 6, and therefore, the resultant force of the oil film reaction forces acts to rotate the piston 3 in the radial field of view, and a tilting moment that rotates the piston 3 is applied to the shaft.

The oil film reaction force and the overturning moment are larger at the time of high-speed rotation, and therefore, the problem becomes larger when the maximum rotation speed is high as the product specification of the compressor.

Claims

1. A compressor is provided with:

a cylinder tube having a cylinder liner provided with a cylindrical gap; and

a piston reciprocating in the gap,

lubricating oil is supplied between the cylinder liner and the piston,

the above-mentioned compressor is characterized in that,

the cylinder liner has a first cutout portion and a second cutout portion that face each other with the gap therebetween.

2. The compressor of claim 1,

either one of the first cutout portion and the second cutout portion is located on the opposite side of the gap from the direction of gravitational acceleration.

3. Compressor according to claim 1 or 2,

the piston has an annular oil supply groove,

the oil supply groove includes, at a bottom dead center of the piston:

a portion exposed from the cylinder liner through the first cutout portion;

a portion exposed from the cylinder liner through the second cutout portion; and

and a portion opposed to the cylinder liner.

4. The compressor of claim 3,

in the above-mentioned oil-supplying tank,

an end portion on a top dead center side of a portion located on the first cutout portion side in the circumferential direction is located on the top dead center side of the first cutout portion at a bottom dead center of the piston, and/or

An end portion on the top dead center side of a portion located on the second cutout portion side in the circumferential direction is located on the top dead center side of the second cutout portion at the bottom dead center of the piston.

5. The compressor according to any one of claims 1 to 4,

in a cross-sectional view of the piston in a reciprocating direction, a part of the second cutout portion falls into a region sandwiched by two imaginary straight lines passing through an end portion of the first cutout portion and a center of the gap, respectively.

6. The compressor according to any one of claims 1 to 4,

in a cross-sectional view of the piston in the reciprocating direction, the entire second cutout portion falls into a region sandwiched by two imaginary straight lines passing through the end of the first cutout portion and the center of the gap, respectively.