EP3037665A1

EP3037665A1 - Hermetic compressor

Info

Publication number: EP3037665A1
Application number: EP14864603.7A
Authority: EP
Inventors: Takamitsu Himeno; Kazuhiko Inoguchi; Takashi Watanabe; Taichi Tateishi; Susumu Matsuda; Yoshiyuki Kimata
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Thermal Systems Ltd
Priority date: 2013-11-19
Filing date: 2014-06-13
Publication date: 2016-06-29
Also published as: JP2015098812A; JP6199708B2; EP3037665A4; WO2015075851A1

Abstract

The present invention prevents damage to a housing in a caulked portion, even if an excessive thrust load occurs in a compression mechanism. A scroll compressor (1) which comprises: the housing (3); the compression mechanism which is accommodated inside the housing (3) ; and a bearing housing (19) which comprises a support section (19d) that receives a thrust load (Fs) occurring due to the action of the compression mechanism, and further comprises a bearing section (19b) that rotatably supports a main shaft (9) which transmits the driving force of a drive source to the compression mechanism. The bearing housing (19) is fixed to the housing (3) by a caulked section (30) at which a plastically deformed portion of the housing (3) is press-fitted into a recess (19a) provided in the bearing housing (19). A deformation-releasing groove (19f) is provided to a surface of the bearing housing (19), said surface opposing the compression mechanism and corresponding to the caulked section (30).

Description

Technical Field

The present invention relates to a hermetic compressor and in particular, to a hermetic compressor in which a member which is referred to as a bearing housing is fixed to a housing by caulking.

Background Art

A hermetic compressor which is used to compress a refrigerant in an air conditioning apparatus and other apparatuses which are provided with a refrigeration cycle is known. The hermetic compressor has a configuration in which, for example, a scroll compression mechanism and an electric motor which is a driving source thereof are accommodated in a housing which forms an outer shell. The scroll compression mechanism compresses a fluid by disposing a fixed scroll and an orbiting scroll, which are provided with spiral wraps, in combination with each other, and gradually reducing the volume of a compression chamber which is formed between the wraps, by revolving the orbiting scroll with respect to the fixed scroll.
In a hermetic compressor, a compression mechanism is fixed to a housing through a bearing housing, and as one type of fixing means, caulking is known (for example, PTL 1 and PTL 2). According to PTL 2, due to higher-speed rotation in an operation of a compression mechanism, in addition to an increase in the pressure specifications of a refrigerant in a hermetic compressor, a load of a portion fixing a bearing housing increases, and thus, to that end, caulking is effective. PTL 2 proposes a fixing structure in which an engagement margin having sufficient strength with respect to a high-pressure refrigerant is formed by providing a caulked section obtained by plastically deforming a housing, at a plurality of locations. A bearing housing has a function to receive a thrust load occurring due to an operation of a compression mechanism and a function to rotatably support a main shaft which transmits a drive force of a driving source to a compression mechanism.

Citation List

Patent Literature

[PTL 1] Japanese Patent No. 3567237
[PTL 2] Japanese Unexamined Patent Application Publication No. 2008-128036

Summary of Invention

Technical Problem

As described above, fixing is performed by caulking, whereby it is possible to obtain high fixing strength. However, if an excessive thrust load acts on the bearing housing from the compression mechanism, deformation occurs in the bearing housing in which caulking is provided. For example, as shown in Fig. 7, in a case where a bearing housing 119 which supports a compression mechanism is fixed to a housing 103 by caulking 130, it is confirmed that there is a concern that the housing 103 may be damaged due to a large load acting on a corner portion O of the housing 103 from an opening edge of a recess 119a formed in the bearing housing 119.
Therefore, the present invention has been made based on such a technical problem and has an object to prevent damage to a housing in a caulked section, even if an excessive thrust load occurs in a compression mechanism, in a hermetic compressor in which a bearing housing is fixed to the housing by caulking.

Solution to Problem

Under such an object, according to the present invention, there is provided a hermetic compressor including: a housing which forms an outer shell hermetically sealed with respect to the outside; a compression mechanism which is accommodated in the housing; and a bearing housing which is provided with a support section that receives a thrust load occurring due to an operation of the compression mechanism, and a bearing section that rotatably supports a main shaft which transmits a drive force of a driving source to the compression mechanism, in which the bearing housing is fixed to the housing by caulking in which a plastically deformed portion of the housing is pressed-fitted into a recess which is provided in the bearing housing, and the bearing housing has a deformation-releasing groove provided at a position corresponding to the caulking and in a surface on the side facing the compression mechanism.
According to the present invention, even if an excessive thrust load acts on the bearing housing, a portion further toward the inner periphery side than the deformation-releasing groove, is preferentially deformed, whereby the thrust load is prevented from being transmitted to the caulking which is located further toward the outer periphery side than the deformation-releasing groove. Therefore, it is possible to prevent an opening edge of the recess of the bearing housing from damaging the housing at a caulked section.
In the hermetic compressor according to the present invention, it is preferable that an opening edge of the recess which is provided in the bearing housing is R-machined, because it is possible to prevent local stress from occurring in the housing due to receiving a load from the opening edge of the recess.
In the hermetic compressor according to the present invention, it is preferable that the recess which is provided in the bearing housing is formed in a tapered shape which is tapered toward an inner part from an opening edge, because a large press-fit margin of the housing which is fastened to the recess can be obtained.
According to the present invention, in response to the occurrence of an especially excessive thrust load, a self-aligning mechanism can be interposed between the recess and the plastically deformed portion of the housing.
According to this hermetic compressor, even if the thrust load acts, whereby deformation occurs in the bearing housing, the self-aligning mechanism functions, thereby absorbing the deformation, and therefore, it is possible to prevent damage to the housing.

Advantageous Effects of Invention

According to the present invention, even if an excessive thrust load acts on the bearing housing, it is possible to prevent the opening edge of the recess of the bearing housing from damaging the housing at the caulked section.

Brief Description of Drawings

Fig. 1 is a partial cross-sectional view showing a scroll compressor of a first embodiment.
Figs. 2(a) to 2(c) are diagrams showing a procedure of forming a caulked section in the scroll compressor of Fig. 1.
Figs. 3(a) and 3(b) are diagrams describing an operation and an effect in the scroll compressor of Fig. 1.
Figs. 4(a) and 4(b) are diagrams showing examples of a deformation-releasing groove in the scroll compressor of Fig. 1.
Figs. 5(a) and 5(b) are diagrams showing preferred forms of a caulked section of the scroll compressor of Fig. 1.
Figs. 6(a) and 6(b) are diagrams showing a caulked section of a second embodiment.
Fig. 7 is a diagram showing a caulked section in a scroll compressor of the related art.

Description of Embodiments

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings. In the embodiments, the present invention will be described taking a scroll compressor as an example of a hermetic compressor.

[First Embodiment]

A scroll compressor 1 according to this embodiment is provided with a housing 3, a fixed scroll 5, an orbiting scroll 7, a main shaft 9, and a rotation-preventing section 11, as shown in Fig. 1, and a bearing housing 19 is fixed to the housing 3 by caulking. Further, in the scroll compressor 1, a deformation-releasing groove 19f which prevents damage from occurring in a caulked section, even if an excessive thrust load is applied, is provided in the bearing housing 19. Hereinafter, after the respective constituent elements of the scroll compressor 1 are described in order, the deformation-releasing groove 19f will be described.
The housing 3 is a hermetically-sealed container in which members configuring a compression mechanism, such as the fixed scroll 5 and the orbiting scroll 7, are accommodated and installed, as shown in Fig. 1. A discharge cover 13, a suction pipe (not shown), a discharge pipe 17, and the bearing housing 19 are provided in the housing 3. The discharge cover 13 is for separating the interior of the housing 3 into a high-pressure chamber HR and a low-pressure chamber LR.
The suction pipe is for leading a low-pressure refrigerant from the outside to the low-pressure chamber LR, and the discharge pipe 17 is for leading a high-pressure refrigerant from the high-pressure chamber HR to the outside. The bearing housing 19 is for supporting the compression mechanism composed of the fixed scroll 5 and the orbiting scroll 7 and rotatably supporting the main shaft 9.
The main shaft 9 is for transmitting a rotational driving force of an electric motor (not shown), which is provided on the lower side of the interior of the housing 3, to the orbiting scroll 7. The main shaft 9 is substantially perpendicularly and rotatably supported in the interior of the housing 3. An eccentric pin 9a which drives the orbiting scroll 7 so as to revolve is provided at an upper end portion of the main shaft 9. The eccentric pin 9a is a columnar member which is provided at a position eccentric by an orbiting revolution radius r of the orbiting scroll 7 from the rotation center of the main shaft 9 on an upper end face of the main shaft 9.
The fixed scroll 5 and the orbiting scroll 7 are for compressing a fluid which has flowed into the low-pressure chamber LR of the housing 3, and then discharging the fluid to the high-pressure chamber HR. The fixed scroll 5 and the orbiting scroll 7 are disposed such that the fixed scroll 5 and the orbiting scroll 7 are respectively disposed on the upper side and the lower side in the interior of the housing 3 and both the scrolls 5 and 7 are engaged with each other.
The fixed scroll 5 is supported on the bearing housing 19 from the lower side through the orbiting scroll 7, thereby being disposed at a fixed position of the housing 3. A discharge port 21 through which the compressed fluid is discharged is provided at the back face center (the upper surface center in Fig. 1) of an end plate 5a of the fixed scroll 5. On the other hand, the orbiting scroll 7 is supported on the bearing housing 19 so as to be able to revolve with respect to the fixed scroll 5. A boss 23 into which the eccentric pin 9a of the main shaft 9 is inserted is provided at the back face center (the lower surface center in Fig. 1) of an end plate 7a of the orbiting scroll 7. Similarly, in the back face of the end plate 7a, a recessed portion 25 in which a ring 27 of the rotation-preventing section 11 is disposed is formed on a circle having a predetermined radius from the center of the orbiting scroll 7. The recessed portion 25 is formed in a substantially circular shape when viewed from the main shaft 9 side.
The bearing housing 19 is a substantially annular member which is supported on the housing 3 by a caulked section 30.
The bearing housing 19 is provided with a bearing section 19b which is located on the inner periphery side and rotatably supports the main shaft 9, a fixed section 19c which is located on the outer periphery side and faces the housing 3, a support section 19d which is provided further toward the outer periphery side than the bearing section 19b and supports the orbiting scroll 7, and a connecting section 19e which connects the fixed section 19c and the support section 19d, as shown in Fig. 3(a).
The bearing housing 19 supports the orbiting scroll 7 in a vertical direction at the support section 19d, and therefore, if a refrigerant is compressed between the orbiting scroll 7 and the fixed scroll 5, the support section 19d receives a thrust load Fs. In this embodiment, the caulked section 30 is provided at a plurality of locations, whereby even if the bearing housing 19 receives an excessive thrust load Fs, the bearing housing 19 can take the load. In addition, in this embodiment, the deformation-releasing groove 19f is formed in the bearing housing 19 such that, even if the bearing housing 19 receives an excessive thrust load, the housing 3 is prevented from being damaged due to receiving a local load from the bearing housing 19. The deformation-releasing groove 19f will be described in more detail along with the caulked section 30 which will be described later.
In the scroll compressor 1 having the configuration described above, a plurality of caulked sections 30 disposed at regular intervals, for example, 120-degree intervals, in a circumferential direction are formed at proper places of the side face of the compression mechanism in order to fix the bearing housing 19 accommodated in the housing 3.
The caulked section 30 is formed by fitting a portion of the housing 3 into a recess 19a formed by recessing a portion of the bearing housing 19, as shown in Fig. 2(c). The recess 19a is formed in advance, as shown in Fig. 2 (a). After the recess 19a is covered with the housing 3, as shown in Fig. 2(b), the caulked section 30 is formed by plastically deforming a portion of the housing 3 in a recessed portion shape by pressing a punch 40 so as to drive it toward the recess 19a from the outside of the housing 3, as shown in Fig. 2(c).
When forming the caulked section 30, it is preferable that an inner diameter d of the recess 19a and an outer diameter D of the punch 40 are set to the same dimension (d=D), as shown in Fig. 2. Then, the housing 3 pressed by a protrusion of the punch 40 is plastically deformed, thereby entering into the recess 19a and being engaged with the bearing housing 19 side, whereby the length of an engagement margin can be secured, and therefore, it is possible to obtain sufficient caulking strength.
If the caulked sections 30 having sufficient strength in this method are formed at an equal pitch in the circumferential direction at a plurality of locations, it is possible to reliably fix the bearing housing 19 by the caulked sections 30 with an engagement margin having sufficient strength formed therein, even with respect to the housing 3 with a plate thickness increased for coping with a high-pressure refrigerant.
Further, when forming the caulked section 30 between the housing 3 and the bearing housing 19, it is preferable to plastically deform a location corresponding to the caulked section 30, of the housing 3, by heating (for example, in a range of 700°C to 800°C) the location, because workability can be greatly improved.
In the scroll compressor 1, in response to the formation of the caulked section 30, the deformation-releasing groove 19f is formed along the circumferential direction in the bearing housing 19, as shown in Figs. 1, 3, and 4. The deformation-releasing groove 19f is formed in the upper surface of the connecting section 19e, that is, the surface on the side facing the compression mechanism composed of the fixed scroll 5 and the orbiting scroll 7, of the connecting section 19e.
In the bearing housing 19, as shown in Fig. 3(a), the support section 19d which receives the thrust load Fs serves as a point of action Pa and the caulked section 30 serves as a fulcrum Ps. Therefore, a bending moment M in a clockwise direction in the drawing occurs in the bearing housing 19 with the caulked section 30 as the fulcrum Ps. At this time, the deformation-releasing groove 19f is provided in a range of a line segment connecting the fulcrum Ps and the point of action Pa and on the side to which the thrust load Fs is applied, with the line segment as a boundary.
As described above, in the bearing housing 19 which is provided with the deformation-releasing groove 19f, an excessive thrust load Fs is assumed to act on the support section 19d. Then, as shown in Fig. 3(b), the portion further toward the inner periphery side than the deformation-releasing groove 19f is deformed, whereby the thrust load Fs is prevented from being transmitted to the caulked section 30 which is located further toward the outer periphery side than the deformation-releasing groove 19f. Therefore, a corner portion of the recess 19a of the bearing housing 19 can be prevented from damaging the housing 3 at the caulked section 30.
The deformation-releasing groove 19f can be formed in the form of a ring connected continuously in the circumferential direction, as shown in Fig. 4(a), and can also be formed to be divided into a plurality of sections in the circumferential direction, as shown in Fig. 4(b). In any case, the deformation-releasing groove 19f needs to be provided corresponding to the caulked section 30. Here, the expression, corresponding to the caulked section 30, refers to the deformation-releasing groove 19f being formed to overlap a line segment connecting each of the caulked sections 30 and the center of the bearing housing 19. If so, it is possible to obtain the above-described effect of preventing the thrust load Fs from being transmitted to the caulked section 30.
Further, the deformation-releasing groove 19f has been thus far described as having an arc shape in a plan view. However, the present invention is not limited thereto, and as long as the effect of preventing the thrust load Fs from being transmitted to the caulked section 30 is exhibited, a shape in a plan view does not matter. For example, the deformation-releasing groove 19f may be formed in a straight line shape and may be formed in a chevron shape peaking toward the outer periphery side.
The deeper the depth of the deformation-releasing groove 19f, the more easily the portion on the inner periphery side is deformed. However, since the strength of the bearing housing 19 decreases, it is desirable to select a depth taking into account these two factors. As one guideline, a range of about 1/10 to 2/10 of the wall thickness of a portion (in this embodiment, the connecting section 19e) in which the deformation-releasing groove 19f is provided is set as a reference. It is favorable if the width of the deformation-releasing groove 19f is also set according to the same guideline. For example, it is possible to set the wall thickness of the bearing housing 19 (the wall thickness of the portion in which the deformation-releasing groove 19f is provided) to be in a range of 10 mm to 20 mm. In a case where the wall thickness of the bearing housing 19 is 10 mm, it is favorable if the depth of the deformation-releasing groove 19f is set to be in a range of 1 mm to 2 mm and the width is set to be in a range of about 1 mm to 2 mm. Further, in a case where the wall thickness of the bearing housing 19 is 20 mm, it is favorable if the depth of the deformation-releasing groove 19f is set to be in a range of 2 mm to 4 mm and the width is set to be in a range of about 2 mm to 4 mm.
Elements which are preferable to adopt in the first embodiment will be described with reference to Fig. 5.
First, as shown in Fig. 5(a), by performing R-machining on an opening edge of the recess 19a of the bearing housing 19, it is possible to more reliably prevent stress concentration from occurring in the housing 3. It is preferable that a radius of curvature in the R-machining is set to be greater than or equal to 1 mm in order to reduce stress concentration.
Further, the same effect as in the R-machining can also be obtained by chamfering.
Next, the shape of the recess 19a will be described. As shown in Fig. 5(b), it is preferable to machine the recess 19a in a tapered shape which is tapered toward the inner part of the recess 19a from the opening edge. If it approaches the inner part of the recess 19a, the opening diameter becomes narrower, and therefore, a large press-fit margin of the housing 3 which is fastened to the recess 19a can be obtained. Therefore, it is possible to increase fastening force between the bearing housing 19 and the housing 3 in the caulked section 30, and therefore, fixation by the caulked section 30 can be more reliably made.
A preferred range is present in the degree of the inclination of the taper, and thus, if the diameter of the opening edge of the recess 19a is set to be φD and the diameter of the inner part side is set to be φd, according to the following expression, the effect due to the formation of the taper becomes remarkable. $ϕd \leq 0.998 \times ϕD$

[Second Embodiment]

Next, a second embodiment of the present invention will be described with reference to Fig. 6. The second embodiment corresponds to a case where a thrust load is larger. In addition, in the following, description will be made with a focus on differences from the first embodiment, and the same elements as those in the first embodiment are denoted by the same reference numerals in Fig. 6.
In the second embodiment, a self-aligning bearing 50 is interposed in the caulked section 30.
The self-aligning bearing 50 is provided with an inner ring 51, an outer ring 53, a rolling element 55 which is provided between the inner ring 51 and the outer ring 53, and a cage (not shown), as shown in Fig. 6(a). The self-aligning bearing 50 has an alignment property that the axes of the inner ring 51, the rolling element 55, and the cage can freely rotate around the bearing center, because the raceway surface of the outer ring 53 is a spherical surface and the center of curvature coincides with the bearing center. In general, an allowable aligning angle is in a range of about 0.07 radians to 0.12 radians (a range of 4 degrees to 7 degrees).
The self-aligning bearing 50 is interposed between the recess 19a and a plastically deformed portion of the housing 3 with the inner ring 51 provided to radially face the housing 3 side and the outer ring 53 provided to radially face the bearing housing 19 side, as shown in Fig. 6.
In order to provide the self-aligning bearing 50 at the caulked section 30, after the caulked section 30 is formed in the same manner as the first embodiment, caulking is released. Then, after machining for enlarging the opening diameter of the bearing housing 19 so as to be able to press-fit the self-aligning bearing 50 therein is performed, the self-aligning bearing 50 is assembled to be interposed between the housing 3 and the bearing housing 19.
According to the caulked section 30 of the second embodiment, even if a very large thrust load acts, whereby deformation occurs in the bearing housing 19, the self-aligning bearing 50 functions, thereby absorbing the deformation, as shown in Fig. 6(b), and therefore, it is possible to prevent damage to the housing 3.
In addition, the self-aligning bearing 50 shown in the second embodiment may be applied to the caulked section 30 of the hermetic compressor shown in the first embodiment.
The present invention has been described above based on the embodiments. However, it is possible to make a choice between the configurations mentioned in the above embodiments or appropriately change the configurations to other configurations as long as it does not depart from the scope of the present invention.
For example, in the above, the scroll compressor has been described as an example of the hermetic compressor. However, it is also possible to apply the present invention to a scroll compression mechanism part of a hermetic compressor which is provided with both a rotary compression mechanism and a scroll compression mechanism as a compression mechanism.
Further, the structure of the bearing housing 19 is arbitrary as long as it has a function to support a thrust load occurring due to an operation of a compression mechanism and a function to slidably support a main shaft which transmits a drive force of a driving source to a compression mechanism.

Reference Signs List

1: scroll compressor
3: housing
5: fixed scroll
5a: end plate
7: orbiting scroll
7a: end plate
9: main shaft
9a: eccentric pin
11: rotation-preventing section
13: discharge cover
17: discharge pipe
19: bearing housing
19a: recess
19b: bearing section
19c: fixed section
19d: support section
19e: connecting section
19f: deformation-releasing groove
21: discharge port
23: boss
25: recessed portion
27: ring
30: caulked section
40: punch
50: self-aligning bearing
51: inner ring
53: outer ring
55: rolling element
D: outer diameter
d: inner diameter
Fs: thrust load
HR: high-pressure chamber
LR: low-pressure chamber
M: moment

Claims

A hermetic compressor comprising:
a housing which forms an outer shell hermetically sealed with respect to the outside;

a compression mechanism which is accommodated in the housing; and

a bearing housing which is provided with a support section that receives a thrust load occurring due to an operation of the compression mechanism, and a bearing section that slidably supports a main shaft which transmits a drive force of a driving source to the compression mechanism,

wherein the bearing housing is fixed to the housing by caulking in which a plastically deformed portion of the housing is pressed-fitted into a recess which is provided in the bearing housing, and

the bearing housing has a deformation-releasing groove provided at a position corresponding to the caulking and in a surface on the side facing the compression mechanism.
The hermetic compressor according to Claim 1, wherein an opening edge of the recess which is provided in the bearing housing is R-machined.
The hermetic compressor according to Claim 1 or 2, wherein the recess which is provided in the bearing housing is formed in a tapered shape which is tapered toward an inner part from an opening edge.
The hermetic compressor according to any one of Claims 1 to 3, wherein the recess which is provided in the bearing housing is formed in an outer periphery-side face of the bearing housing.
The hermetic compressor according to any one of Claims 1 to 4, wherein the bearing housing is a substantially annular member,
the bearing section is located on the inner periphery side of the bearing housing, and
the support section is located further at an outer periphery than the bearing section.
The hermetic compressor according to Claim 5, wherein the bearing housing is further provided with a fixed section and a connecting section,
the fixed section is located on the outer periphery side of the bearing housing and faces the housing, and
the connecting section is provided so as to connect the fixed section and the support section.
The hermetic compressor according to Claim 6, wherein the deformation-releasing groove is provided in the connecting section of the bearing housing.
The hermetic compressor according to Claim 7, wherein the deformation-releasing groove is provided in an upper surface of the connecting section.
The hermetic compressor according to Claim 1, wherein a self-aligning mechanism is interposed between the recess and the plastically deformed portion of the housing.
The hermetic compressor according to any one of Claims 1 to 9, wherein the hermetic compressor is a scroll compressor, and
the compression mechanism includes an orbiting scroll and a fixed scroll.
The hermetic compressor according to Claim 10, wherein the support section of the bearing housing supports the orbiting scroll in a vertical direction.
A hermetic compressor comprising:
a housing which forms an outer shell hermetically sealed with respect to the outside;

a compression mechanism which is accommodated in the housing; and

a bearing housing which is provided with a support section that receives a thrust load occurring due to an operation of the compression mechanism, and a bearing section that slidably supports a main shaft which transmits a drive force of a driving source to the compression mechanism,

wherein the bearing housing is fixed to the housing by caulking in which a plastically deformed portion of the housing is pressed-fitted into a recess which is provided in the bearing housing, and

a self-aligning mechanism is interposed between the recess and the plastically deformed portion of the housing.