GB2167131A

GB2167131A - Scroll-type rotary fluid-machine

Info

Publication number: GB2167131A
Application number: GB8429203A
Authority: GB
Inventors: Seiichi Sakamoto
Original assignee: Sanden Corp
Current assignee: Sanden Corp
Priority date: 1984-11-19
Filing date: 1984-11-19
Publication date: 1986-05-21
Also published as: SE8405889L; GB8429203D0; AU3575084A; FR2574866A1; SE457903B; SE8405889D0; DE3442620A1

Abstract

The machine may be compressor and has a drive shaft 13 supported by a bearing 30 lodged in an end plate 11 of a housing 10 and carrying a seal assembly 20, which is accommodated by an annular sleeve 17 projecting from the said plate. <IMAGE>

Description

SPECIFICATION Scroll type fluid displacement apparatus This invention relates to a fluid displacement apparatus, and more particularly, to an improve drive shaft supporting mechanism for use in a scroll type fluid displacement apparatus.

Scroll type fluid displacement apparatus are well known in the prior arts. For example, U.S. Patent No. 801,182 issued to Creux discloses basic construction which includes a pair of scrolls each having a circular end plate and a spiroidal or involute spiral element. These scrolls are maintained angularly and radially offset so that both spiral elements interfit to make a plurality of line contacts between spiral curved surfaces thereby to seal off and define at least one pair of fluid pockets. The relative orbital motion of the two scrolls shifts the line contact along the spiral curved surfaces and, therefore, the fluid pockets change in volume. The volume of the fluid pocket increases or decreases dependent on the direction of the orbital motion. Therefore, the scroll type fluid displacement apparatus is applicable to compress, expand or pump fluids.

Typically,a drive shaft receives and transmits a rotary driving force from an external power source. The drive shaft is rotatably supported by a bearing means disposed within a housing. In particularly, as shown in U.S. Patent No. 4,435,136, the drive shaft is rotatable supported by the two bearing means disposed within the housing.

Referring to Fig. 1, such drive shaft supporting construction will be described. A drive shaft 13' has a disk shaped portion 15' at its inner end portion and is rotatably supported by a first bearing means 19' disposed within an annular sleeve 17' projecting from a front end surface of front end plate 11'. Disk shaped portion 15' is also rotatably supported by a second bearing means 16' disposed within an opening 111' formed in the center portion of front end plate 11'. A drive pin or crank pin (not shown) axially projects from end surface of disk shaped portion 15', and is radially offset from the center of drive shaft 13'. The drive pin is connected to a bushing 271' and an orbiting scroll 26' is rotatably supported on bushing 271' through a radial bearing 272'. The orbiting scroll 26' is also connected to a rotation preventing/thrust bearing means 28'.Therefore, orbiting scroll 26' is allowed to undergo the orbital motion by the rotation of drive shaft 13'.

In the above described drive shaft supporting construction, the distance between the first and second bearings 16' and 19' should be made longer to improve the durability of these bearings 16', 19' due to reduce the load acting on the two bearings. Thus, a shaft seal assembly 20' should be assembled on drive shaft 13' to placed between the first and second bearings for reducing the axial length of the compressor. On the other hand, the shaft seal assembly should be assembled on drive shaft 13' for achieving the desorption to enabling the repair it. But, the shaft seal assembly is placed between the two bearings, the repairing of shaft seal assembly is complicated, and achieving of easy desorption of shaft seal assembly could not done with simple construction.Furthermore, since one of the bearing 19' should be placed on outside of shaft seal assembly 20', those bearing 19' is provide with grease seal mechanism.

It is a primary object of this invention to provide a scroll type fluid displacement apparatus with an improved desorption of a shaft seal assembly while held the durability of the bearing which supports the drive shaft.

It is another object of this invention to provide a scroll type fluid displacement apparatus wherein the assembly of the apparatus is simplified by reducing the constructing parts.

It is still another object of this invention to provide a scroll type fluid displacement apparatus which accomplishes the above described objects, is simple in construction and production.

A scroll type fluid displacement apparatus according to this invention includes a housing having a front end plate. A fixed scroll member is fixedly disposed within the housing and has a circular end plate from which a first wrap extends. An orbiting scroll has a circular end plate from which a second wrap extends.

The first and second wraps interfit at an angularly and radially offset to make a plurality of line contacts to define at least one pair of sealed off fluid pocket. A driving mechanism is operatively connected to the orbiting scroll to effect the orbital motion of the orbiting scroll. A rotation preventing mechanism is also connected to the orbiting scroll for preventing the rotation of orbiting scroll to thereby changes the volume of the fluid pockets. The front end plate comprises a front end plate portion in which an opening is formed for penetrating a drive shaft, and an annular sleeve portion extends from a front end surface of the front end plate portion for surrounding the drive shaft to define a shaft seal cavity. The drive shaft is rotatably supported by the front end plate through a double acting angular ball bearing disposed in the opening of front end plate portion.A shaft seal assembly is assembled on the drive shaft to placed axially outwardly portion of the bearing and placed in the shaft seal cavity of sleeve.

Further objects, features and other aspects of this invention will be understood from the following the detailed description of preferred embodiment of this invention with reference to the annexed drawings.

Figure 1 is a vertical sectional view of a prior compressor unit.

Figure 2 is a vertical sectional view of a scroll type fluid compressor according to one embodiment of this invention.

Figure 3 is a vertical sectional view of a main portion of a bearing fastening construction according to another embodiment of this invention.

Referring to Fig. 2, a scroll type fluid displacement apparatus in accordance with the present invention, in particular a scroll type fluid compressor unit 1, is shown. The compressor unit 1 includes a housing 10 comprising a front end plate 11 and a cup shaped casing 12 which is attached to an end surface of front end plate 11. An opening 111 is formed in the center of front end plate 11 for penetration or passage of a drive shaft 13.

An annular projection 112 which is concentric with opening 111 is formed on rear end surface of front end plate 11 to face cup shaped casing 12. An outer peripheral surface of annular projection 112 extends into an inner wall of the opening of cup shaped casing 12.

Thus, the opening of cup shaped casing 12 is covered by front end plate 11. An O-ring 14 is placed between the outer peripheral surface of annular projection 112 and the inner wall of cup shaped casing 12 to seal the mating surfaces of front end plate 11 and cup shaped casing 12.

An annular sleeve 17 projects from the front end surface of front end plate 11 to surround drive shaft 13 and define a shaft seal cavity. In the embodiment shown in Fig.

2, sleeve 17 is formed integral with front end plate 11 to achieve easy production and assembly of the compressor unit.

Drive shaft 13 has a disk shaped portion 15 at its inner end which is rotatably supported by front end plate 11 through an double acting angular ball bearing 30 located within opening 111 of front end plate 11. An outer end surface of outer race of angular ball bearing 30 is fitted against a step portion 171 formed on the inner wall surface of sleeve 17 and calking is performed on the outer peripherai portion of opening 111 to prevent the axial movement of angular ball bearing 30. As shown in Fig. 3, snap ring 31 may be disposed in the inner wall of opening 111 to fitted against the inner end surface of outer race of angular ball bearing 30 to prevent the axial movement of angular ball bearing 30. A shaft seal assembly 20 is assembled on drive shaft 13 within the shaft seal cavity of sleeve 17.

Drive shaft 13 is coupled to an electromagnetic clutch 23 which comprises a pulley 231 rotatably supported on the outer peripheral portion of sleeve 17, an electromagnetic coil 232 fixedly disposed within an annular cavity of pulley 231 and an armature plate 233 elastically supported on the outer end portion of drive shaft 13. Thus, drive shaft 13 is driven by an external power source (e.g., the engine of an automobile) through electromagnetic clutch 23.

A number of elements are located within an inner chamber of cup shaped casing 12 including a fixed scroll 25, an orbiting scroll 26, a driving mechanism for orbiting scroll and a rotation preventing/thrust bearing device 28 for orbiting scroll 26. The inner chamber of cup shaped casing 12 is formed between the inner wall of cup shaped casing 12 and front end plate 11.

Fixed scroll 25 includes circular end plate 251 and a wrap or involute spiral element 252 affixed to or extending from a side surface of circular end plate 251. Circular end plate 251 is also formed with a plurality of legs 253 axially projecting from its other side surface thereof. An axial end surface of each hegs 253 is fitted against the inner surface of a bottom plate portion 121 of cup shaped casing 12 and fixed in cup shaped casing 12 by screws (not shown) which screw into legs 253 from the outside of bbttom plate portion 121. Circular end plate 251 of fixed scroll 25 partitions the inner chamber of cup-shaped casing into rear chamber 32 having legs 253 and front chamber 33 in which spiral element 252 of fixed scroll 25 is located.A sealing member 34 is disposed within circumferential groove of circular end plate 251 for sealing the inner wall of cup shaped casing 12 and outer peripheral surface of circular end plate 251.

Orbiting scroll 26, which is disposed in front chamber 33, includes a circular end plate 261 and a wrap or spiral element 262 affixed to or extending from a side surface of circular end plate 261. Both spiral elements 252, 262 interfit at an angular offset of 180 and at a predetermined radial offset. The spiral elements define at least a pair of fluid pockets between their interfitting surfaces. Orbiting scroll 26 is connected to the driving mechanism and rotation preventing/thrust bearing device 28 to effect the orbital motion of orbiting scroll 26 by the rotation of drive shaft 13.

A crank pin or drive pin (not shown) projects axially inwardly from an end surface of disk shaped portion 15 and is radially offset from the center of drive shaft 13. Circular end plate 261 of orbiting scroll 26 is provided with a tubular boss 263 projecting axially outwardly from the end surface opposite to the side from which spiral element 262 extends.

Axial bushing 271 is fitted into boss 263, and is rotatably supported therein by a bearing 272. An eccentric hole (not shown) is formed in bushing 271 radially offset from the center of bushing 271. The drive pin is fitted into the eccentric hole, therefore bushing 271 is driven by the rotation of drive pin. The spiral element of orbiting scroll 26 is thus pushed against the spiral element of fixed scroll 25 due to the moment created between the driving point and the reaction force acting point of the pressurized gas to secure the line contacts and effect radial sealing.

Rotation preventing/thrust bearing device 28 is placed between the inner end surface of front end plate 11 and the end surface of circular end plate 261 which faces the inner end surface of front end plate 11. Rotation preventing/thrust bearing device 28 includes a fixed ring 281, which is fastened against the axial end surface of annular projection 112, orbiting ring 282, which is fastened against the end surface of circular end plate 261 by a fastening device, and a bearing element, such as a plurality of spherical balls 283. Both rings 281 and 282 have a plurality of indentations 284 and 285 and one of spherical balls 283 is retained between each of these indentations 284 and 285. Therefore, the rotation of orbiting scroll 26 is prevented by balls 283, which interact with the edges of indentations 284 and 285 to prevent rotation.Also, these balls 283 carry the axial thrust load from orbiting scroll 26. Therefore, orbiting scroll 26 orbits while maintaining its angular orientation to fixed scroll 25.

As the orbiting scroll 26 orbits, the line contacts between spiral elements 252 and 262 shift toward the center of spiral elements along the surfaces of the spiral element. The fluid pockets. defined by the line contacts between spiral elements 252, 262 move toward the center with consequent reduction of volume, to thereby compress the fluid in the fluid pockets. Therefore, fluid or refrigerant gas introduced into front chamber 33 from an external fluid circuit through a fluid inlet port (not shown) mounted on the cup shaped casing 12 is taken into the fluid pockets formed at the outer portion of the spiral elements 252, 262.

As orbiting scroll 26 orbits, the fluid in fluid pockets is compressed as the pockets move toward the center of the spiral element.

Finally, the compressed fluid is discharged into rear chamber 32, and thereafter, the fluid is discharged to the external fluid circuit through a fluid outlet port (not shown) formed on cup shaped casing 12.

As mention above, the drive shaft is rotatably supported by the bearing, such as double acting angular ball bearing which is disposed within the opening of front end plate, and the shaft seal assembly is located within the shaft seal cavity of the sleeve which is placed outwardly from the angular ball bearing. Therefore, the construction for drive shaft supporting mechanism can be made simple and reduce the member of the parts. Furthermore, repair of the shaft seal assembly is easily done, only remove the armature plate.

This invention have been described in detail in connection with preferred embodiments thereof, but these embodiments are merely example only and this invention is not to be considered as restricted thereto. It will be easily understood by these skill in the art that the variations and modifications can be easily made within the scope of this inventions as defined by the appended claims.

Claims

1. In a scroll type fluid displacement apparatus including a housing having a front end plate, a fixed scroll fixedly disposed within the housing and including a circular end plate from which a first wrap extends, an orbiting scroll including a circular end plate from which a second wrap extends, said first and second wrap interfitting at an angular and radial offset to form a plurality of line contacts to define at least one pair of sealed off fluid pockets, a driving mechanism operatively connected to said orbiting scroll to effect the orbital motion of said orbiting scroll and a rotation preventing means for preventing the rotating motion of said orbiting scroll to thereby changes the volume of the fluid pockets, the improvement comprising said driving mechanism including a drive shaft which penetrates said-front end plate and is rotatably supported by a bearing disposed within a opening of said front end plate, said front end plate has an annular sleeve projecting from an axial end surface thereof for surrounding said drive shaft and define a shaft seal cavity and a shaft seal cavity assembled on said drive shaft within the shaft seal cavity of said annular sleeve.

2. The scroll type fluid displacement apparatus of claim 1 wherein said bearing is double acting angular bearing.

3. The scroll type fluid displacement apparatus of claim 1 wherein said annular sleeve is formed integral with said front end plate.

4. A scroll type fluid displacement apparatus comprising: a housing having a front end plate; a drive shaft; said front end plate comprising a front end plate portion in which is formed an opening through which said drive shaft extends, and an annular sleeve portion extending from a front end surface of said front end plate portion for surrounding said drive shaft to define a shaft seal cavity, said annular sleeve portion being formed integral with said front end plate portion; a fixed scroll fixedly disposed relative to said housing and having a circular end plate from which a first wrap extends into the interior of said housing; an orbiting scroll having a circular end plate from which a second wrap extends, and said first and second wraps interfitting at an angular and radial offset to make a plurality of line contacts to define at least one pair of sealed off fluid pockets; ; driving means including said drive shaft extending through said front end plate and rotatably supported thereby for effecting the orbital motion of said orbiting scroll by the rotation of said drive shaft whereby said fluid pockets change volume by the orbital motion of said orbiting scroll; a bearing being disposed within said opening of said front end plate portion for rotatably supporting said drive shaft; a shaft seal assembly assembled on said drive shaft within the shaft seal cavity of said sleeve portion and outwardly of said bearing.

5. The scroll type fluid displacement apparatus of claim 4 wherein said bearing comprises a double acting angular ball bearing.

6. A scroll type fluid displacement apparatus constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.