EP0916845A2

EP0916845A2 - Seal for a compressor casing

Info

Publication number: EP0916845A2
Application number: EP98120328A
Authority: EP
Inventors: Shigemi c/o Sanden Corporation Shimizu; Kiyoshi c/o Sanden Corporation Miyazawa
Original assignee: Sanden Corp
Current assignee: Sanden Corp
Priority date: 1997-11-17
Filing date: 1998-10-27
Publication date: 1999-05-19
Also published as: EP0916845A3; CN1217432A; JPH11148459A

Abstract

A sealing structure of compressor that can prevent the occurrence of "biting" of a rectangular cross-section sealing member is disclosed. The sealing structure comprises a front housing, terminal surface of a housing, and a sealing member disposed in a circular groove having substantially a rectangular cross-section. By providing a space for absorbing the deformation of the sealing member formed when the front housing is mounted on the housing, the "biting" of the deformation of the sealing member between the front housing and the housing can be effectively eliminated:

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a refrigerator compressor used for an air conditioning system, and, more particularly, to a sealing structure for a refrigerant compressor.

2. Description of the Related Art

Referring to Fig. 1, a general structure of a wobble plate-type compressor is shown. The body of compressor 1 includes front housing 22, housing 21, valve plate assembly 3, and cylinder head 23. Front housing 22 is mounted to the left side (in the figure) terminal surface of housing 21 by a plurality of bolts (not shown). Drive shaft 4 is supported by needle bearing 25, which is provided within a hole bored through the center part of front housing 22. Rotor 5, which has an oblique surface at one end, is fixedly connected to drive shaft 4. Rotor 5 rotatably engages front housing 22 via thrust bearing 26. Wobble plate 6 engages the oblique surface of rotor 5 via thrust bearing 62. The central part of wobble plate 6 is fixed with bevel gear 61, in which a central part spherical hole 61a is bored, with which sphere 73 engages slidably. The opposite surface of sphere 73 engages spherical hole 72a, which is bored at a central part of bevel gear part 72 of fixed gear 7.
Cylinder block 24 is formed on the right side (in the figure) of housing 21. A plurality of cylinder bores 24a are provided equiangularly around the central axis. Central through hole 24b, which is bored at the center of the cylinder block 24, accomodates shaft part 71 of fixed gear 7. Shaft part 71 is slidable in the axial direction, but is prohibited from rotating around the axis by a key (not shown). Spring 74 is accommodated within accommodation hole 71a, which is bored at a central part of shaft part 71 of fixed gear 7. Spring 74 is always pushing on fixed gear 7, sphere 73, and bevel gear 61 with the wobble plate 6 fixed to it, to the oblique surface of rotor 5. Crank chamber 10 is formed in the space within housing 21, which accommodates rotor 5 and wobble plate 6.
Within each cylinder bore 24a, a piston 8 is slidable accommodated. Each piston 8 is connected to wobble plate 6 by piston rod 9.
Cylinder head 23 is mounted, via valve plate assembly 3, on cylinder block 24 by bolts 27. By this structure, suction chamber 23a and discharge chamber 23b are formed within cylinder head 23.
Compressor 1 operates as follows. Drive shaft 4 is driven to rotate by an external source, causing rotor 5 to rotate. Through the rotation of the oblique surface of rotor 5, wobble plate 6 wobbles. Since some part of bevel gear 61 always engages some part of bevel gear part 72 of fixed gear 7, any spinning of wobble plate 6 with respect to the central axis is prohibited. The axial component of the wobbling motion of wobble plate 6 is transferred to piston 8 via piston rod 9, causing the pistons to reciprocate within their respective cylinder bores 24a.
Compressor 1 is connected to a refrigerant circuit (not shown), which is filled with refrigerant gas and lubrication oil. In general, compressor 1 has a route through which suction chamber 23a communicates with crank chamber 10. Further, when compressor 1 starts to operate, refrigerant gas enters crank chamber 10 through a slight gap between piston 8 and cylinder bore 24a. As a result, the pressure P1 of the refrigerant gas in crank chamber 10 increases from about 1 kg/cm² to about 10 kg/cm². On the other hand, the atmospheric pressure P0 outside compressor 1 is about 0 kg/cm², so that the relationship between the pressure in crank chamber 10 and the atmosphere is P1>P0.
If there is any leakage of refrigerant gas, refrigerant gas and lubricating oil leak out of crank chamber 10 to the atmosphere due to the pressure differential. The refrigerating capability of the refrigerant circuit decreases as the leakage progresses, finally decreasing to a neglible level. Similarly, because lubrication oil also leaks, the lubrication of the compressor is decreased. Therefore, it is necessary to provide a sealing structure to prohibit any leakage of refrigerant gas from crank chamber 10.
The part enclosed within small circle II in Fig. 1 is the one that requires such a sealing structure.
Fig. 2 is an enlarged view of a conventional structure within small circle II of Fig. 1. Ring-shaped sealing member 28 comprises four surfaces: inner side surface 28A; bottom surface 28B; outer side surface 28C; and upper side surface 28D. Ring-shaped sealing member 28 has a rectangular cross-section in its natural state. Ring-shaped sealing member 28 is made of refrigerant-durable, and lubrication-durable elastic material. Ring-shaped sealing member 28 is accommodated in groove 21e' having a rectangular cross-section and is provided in the terminal surface of housing 21. Groove 21e' comprises inner side inner side wall 21A, bottom 21B, and outer side wall 21C. It is known to dispose the sealing surfaces at outer side, when the inner pressure, namely the crank chamber pressure P1, is greater than the atmospheric pressure P0 outside compressor 1. That is, in accordance with this practice, a seal is usually disposed so that three sealing surfaces can be formed, one of which is formed by the contact of the upper surface 28D of the sealing member 28 and the bottom (in the figure) surface 22D of the front housing 22, the other one of which is formed by the contact of the outer side surface 28C of the sealing member 28 and the outer side wall 21C of the groove 21e', the remaining being formed by the contact of the bottom surface 28B of the sealing member 28 and the bottom 21B of the groove 21e'. In other words, the inner and outer radius of the sealing member 28 are designed such that, along entire circle of the groove 21e', the inner side surface 28A does not touch the inner side wall 21A of the groove 21e', and, at the same time, the outer side surface 28C of the sealing member 28 is in contact with the outer side wall 21C of the groove 21e'.
The thickness d of the sealing member 28 in its natural state is designed to be slightly greater than the depth h of groove 21e'. Accordingly, when front housing 22 is mounted on the terminal surface of housing 21, sealing member 28 will be "squashed" to form the above-mentioned three contact surfaces. Of the deformation of the sealing member 28 made by this "squashing," the deformation of the inner side surface 28A, i.e., an inward bulging, is not restricted, and is accommodated within the empty space been inner surface 28A of sealing member 28 and inner side wall 21A of groove 21e'. On the other hand, for the reason of design mentioned above, outer side surface 28C almost touches outer side wall 21C of groove 21e' from the beginning. So, the deformation of outer side surface 28C of sealing member 28, namely the outward bulging of the outer side surface 28C, is inhibited by outer side wall 21C of groove 21e'.
When front house 22 is mounted on the terminal surface of housing 21, occasionally edge X, which is the corner between outer side surface 28C and upper surface 28D of sealing member 28, is not pushed into groove 21e', but is instead "bulges out" between front house 22 and housing 21 and is "bitten," or caught, therebetween. The "biting" of edge X of sealing member 28, of which a thickness reaches about 0.1 mm, is major cause of the leak from the crank chamber that may be fatal to the compressor. The "biting" occurs randomly, making it practically unpredictable. Therefore, with the current sealing structure, it has been impossible to effectively eliminate the occurrence of the "biting."
If an O-ring having a circular cross-section instead of a rectangular cross-section, mentioned above, is used as the sealing member, the "biting" problem may be easily resolved. An O-ring with a circular cross-section, however, is very expensive, since it must be made individually by a molding process. A sealing member with rectangular cross-section is inexpensive, because it may be made in large quantities by slicing a thin tubular material.
Thus, it has been long desired to improve the sealing structure of compressor to resolve the biting problem, while continuing to use the inexpensive sealing member that has a rectangular cross-section.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a sealing structure of compressor which can prevent the occurrence of "biting" the sealing member. Specifically, it is the object of the present invention to provide a sealing structure for compressor which effectively prevents the sealing member having a rectangular cross-section from being "bitten" when the front housing is mounted on the housing.
According to one embodiment of the present invention, a space which can absorb the deformation of the edge of the sealing member which would be otherwise "bitten," is provided at the fringe of the outer side wall of the groove that accommodates the sealing member. This absorbing space is formed by chamfering the fringe of the outer side wall of the groom. By this device, the deformation of the outer upper edge of the sealing member, which would be otherwise "bitten" between the front housing and the housing, will be absorbed into this absorbing space, so that the occurrence of "biting" can be effectively suppressed.
According to another embodiment of the present invention, the surface of the outer side wall of the groove is tapered so that the whole deformation of the outer side surface part of the sealing member is accommodated therein. That is, the edge of the sealing member is let to move to downward direction when the sealing member is "squashed" by the front housing, so that the deformation of the edge of the sealing member will not be yielded. Thus, the occurrence of "biting" can be effectively suppressed.
According to further embodiment of the present invention, accommodating space for the deformation of the outer side surface part of the scaling member is provided on the front housing surface at the location of the edge of the sealing member. By this device, even if some deformation of the sealing member may be yielded, such deformation will be accommodated and confined within this space, so that the occurrence of "biting" can be effectively suppressed.
Other objects, features, and advantages of this invention will be understood from the following detailed description of preferred embodiments with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a cross-section of a wobble-type compressor according to the conventional art.
Fig. 2 is an enlarged view of the circle II of Fig. 1.
Fig. 3 is a partial cross-section of a sealing structure according to the first embodiment of the present invention.
Fig. 4 is a partial cross-section of a sealing structure according to the second embodiment of the present invention.
Fig. 5 is a partial cross-section of a sealing structure according to the third embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to Figs. 3 to 5, three embodiments of the present invention are shown. In all three figures, the front housing is denoted by numeral 22, the housing by 21, and the sealing member by 28. Further, sealing member 28 has four surfaces 28A, 28B, 28C and 28D, as discussed above. The grooves are each denoted by numerals 21a, 21c, and 21e. The walls and bottom comprising the grooves 21a, 21c, and 21e are denoted 21A', 21B', 21C', 21A'', 21B'', 21C'', 21A''', 21B''', and 21C'''.
Referring to Fig. 3, a sealing structure of compressor according to a first embodiment of the present invention is shown. Sealing member 28, which has a rectangular cross-section in its natural state, is disposed in groove 21a of the terminal surface in housing 21. The upper part of outer wall 21C', of groove 21a is chamfered to form surface 21b. The amount of chamfering may vary in relation to the depth of groove 21a. For example, if the depth of groove 21a is 1 mm, then chamfered surface 21b may extend about 0.3 mm in the vertical direction of the figure, with about 45 degrees inclination of the chamfering. By this chamfering, a space is afforded to accommodate edge X of sealing member 28; specifically, to accommodate the "bulging" of the outer side surface part of sealing member 28. That is, as sealing member 28 is "squashed" by front housing 22, the bulging of edge X will be allowed to occupy the area created by surface 21b, but will not occupy the gap between front housing 22 and housing 21. Therefore, the "biting" trouble of sealing member 28 can be effectively eliminated.
Referring to Fig. 4, a sealing structure of compressor according to a second embodiment of the present invention is shown. Sealing member 28, which has a rectangular cross-section in its natural state, in disposed in groove 21c in the terminal surface of housing 21. Outer side wall 21C' of groove 21c is tapered to form sloped surface 21d. The angle of sloped surface 21d, with respect to a vertical direction in the figure, may be about 15 degrees to about 20 degrees. Other angles for sloped surface 21d may also be used. By this tapering, a space for absorbing the entire deformation, or bulging, of sealing member 28, including edge X, is provided. Accordingly, as sealing member 28 is "squashed" by front housing 22, edge X will be forced in the substantially the downward direction, and edge X will not occupy the gap between front housing 22 and housing 21. Therefore, the "biting" trouble of sealing member 28 can be effectively suppressed.
Referring to Fig. 5, a sealing structure of compressor according to a third embodiment of the present invention is shown. Sealing member 28, which has a rectangular cross-section in its natural state, is disposed in groove 21e of terminal surface in housing 21. Shallow groove 22a is prodded at the location of edge X, on bottom surface 22D of front housing 22, such that the inner fringe and outer fringe of the shallow groove 22a straddles the fringe of the outer side wall 21C'. By providing shallow groove 22a, a space is afforded to accommodate the deformation, or bulging, of edge X of sealing member 28, That is, as sealing member 28 is "squashed" by front housing 22, the deformation of edge X will be permitted to enter shallow groove 22a, and will be confined within shallow groove 22a, but will not enter the gap between front housing 22 and housing 21. Therefore, the "biting" trouble of sealing member 28 can be effectively suppressed.
Generally, groove 21e' (Fig. 2), groove 21a (Fig. 3), or groove 21c (Fig. 4), which are provided on the terminal surface of housing 21, are formed using a computer-controlled lathe machine. With reference to Fig. 2, in order to manufacture groove 21e', the bit of the lathe machine is programmed so as to trace a path along vertical inner wall 21A, horizontal bottom 21B, and vertical outer wall 21C. To make a shape of a groove similar to the grooves shown in the Fig. 3 or Fig. 4, is simple, and is possible by a slight modification to the path of the bit. The cost for practicing the present invention is insubstantial. Further, the time required to manufacture the conventional groove 21e' is also insubstantial. The circumstance for manufacturing shallow groove 22a on the bottom surface of front housing 22 is the same. Since there are several parts on front housing 22 which need lathe processing, it will be enough to merely add a little program statements for making shallow groove 22a to the main program.
Thus, the present invention prevents the occurrence of "biting" the sealing member by providing a space for accommodating the deformation of the sealing member. Alternatively, the present invention prevents the occurrence of "biting" of the sealing member by accommodating the entire deformation of the edge side surface of the sealing member to prevent some deformation from being forced out. Therefore, it is possible to effectively suppress the trouble of a sealing member which has rectangular cross-section, and accordingly to suppress effectively the leak failure of compressor, without using a expensive O-ring as a substitute, without incurring any significant additional costs, or any increases in production time.
The present invention has been described with reference to a wobble plate-type compressor. It will be easily understood that the present invention can also be applied to almost very type of compressor that needs effective sealing to prevent leakage, such as slant plate-type compressors, scroll-type compressors, etc.
The invention has been described in detail in connection with the preferred embodiments. These embodiments, however, are merely for example only and the invention is not restricted thereto. It will be understood by those skilled in the art that other variations and modifications can easily be made within the scope of this invention, as defined by the appended claims.

Claims

A sealing structure for a compressor comprising:

a housing;

a front housing that is mounted on a terminal surface of said housing; and

a ring-shaped sealing member disposed in a groove provided on said terminal surface of said housing, said ring-shaped sealing member having a rectangular cross-section;

wherein an upper fringe of an outer side wall of said groove is chamfered in order to absorb a deformation of said ring-shaped sealing member which is generated when said front housing is mounted on said terminal surface of said housing, thereby preventing said edge from being bitten between said terminal surface of said housing and said front housing.
A sealing structure for a compressor comprising:

a housing;

a front housing that is mounted on terminal surface of said housing; and

a ring-shaped sealing member disposed in a groove provided on said terminal surface of said housing, said ring-shaped sealing member having a rectangular cross-section; wherein an outer side wall of said groove is tapered in order to accommodate a deformation of said sealing member which is generated when said front housing is mounted on said terminal surface of said housing, thereby preventing said deformation from being bitten between said terminal surface of said housing and said front housing.
A sealing structure for a compressor comprising:

a housing;

a front housing that is mounted on terminal surface of said housing; and

a ring-shaped sealing member disposed in a groove provided on said terminal surface of said housing, said ring-shaped sealing member having a rectangular cross-section; wherein a shallow groove is provided on said front housing at an upper fringe of an outer side wall of said groove on said terminal surface of said housing, said shallow groove provided in order to accommodate a deformation of said sealing member generated when said front housing is mounted on said terminal surface of said housing and said front housing.