Rotary expansible chamber devices – Working member has planetary or planetating movement – Helical working member – e.g. – scroll
Reexamination Certificate
2000-07-13
2001-12-25
Denion, Thomas (Department: 3748)
Rotary expansible chamber devices
Working member has planetary or planetating movement
Helical working member, e.g., scroll
C418S055200, C418S055600
Reexamination Certificate
active
06332762
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a scroll-type fluid displacement apparatus, and more particularly, to a scroll-type fluid compressor having improved scroll members.
2. Description of Related Art
Scroll-type fluid displacement apparatus, which having a fixed scroll member and an orbiting scroll member, are known in the art. Referring to
FIG. 5
, a known scroll-type fluid displacement apparatus is shown in the form of scroll-type compressor unit
50
. Compressor unit
50
includes cup-shaped casing
1
, front housing
2
, orbiting scroll member
10
and fixed scroll member
11
. Front housing
2
is funnel-shaped and is fixed to the open side of cup shaped casing
1
by a plurality of screws (not shown).
Annular sleeve
2
a
projects from the center portion of front housing
2
. Drive shaft
3
penetrates annular sleeve
2
a
and reaches the inside of cup-shaped casing
1
. Drive shaft
3
is rotatably supported by annular sleeve
2
a
through bearings
4
and
5
. Drive apparatus
6
is secured on the projecting part of drive shaft
3
, which projects from front housing
2
. Drive apparatus
6
comprises pulley
7
and electromagnetic clutch
8
. An external driving force (not shown) rotates pulley
7
, and a transmission device (not shown) transmits the driving force of the external driving force. Pulley
7
is rotatably supported by the projecting part of housing
2
. Electromagnetic clutch
8
transmits a rotating force of pulley
7
to drive shaft
3
, or disconnects a rotating force of pulley
7
from drive shaft
3
.
Orbiting scroll member
10
and fixed scroll member
11
are disposed in cup-shaped casing
1
. Fixed scroll member
11
is disposed in the bottom portion of cup-shaped casing
1
, and orbiting scroll member
10
, which interfits with fixed scroll member
11
, is disposed in the open side of cup-shaped casing
1
. Fixed scroll member
11
is secured on cup-shaped casing
1
by a plurality of screws
25
, which thread from the outside of the bottom portion of cup-shaped casing
1
.
Orbiting scroll member
10
comprises first end plate
13
and first spiral element
14
, which is formed on first end plate
13
. Orbiting scroll member
10
is eccentrically connected to drive shaft
3
. Therefore, orbiting scroll member
10
is driven in an orbital motion by the rotation of drive shaft
3
in cup-shaped casing
1
.
Fixed scroll member
11
comprises second end plate
16
and second spiral element
17
, which is formed on second end plate
16
. Discharge chamber
12
is defined by the bottom of the inner surface of cup-shaped casing
1
and second end plate
16
. Discharge port
15
is formed in the central part of second end plate
16
. Reed valve
20
, which is plate-shaped, is formed to be movable on discharge port
15
between a closed position and an open position. Valve retainer
21
is formed on reed valve
20
to limit the open movement to a predetermined amount or degree.
Second end plate
16
isolates two chambers in cup-shaped casing
1
, discharge chamber
12
and suction chamber
23
. Orbiting scroll member
10
is disposed in suction chamber
23
, which sucks refrigerant gas from the outside. First spiral element
14
of orbiting scroll
10
and second spiral element
17
of fixed scroll member
11
interfit at a predetermined angular offset.
The side wall part of cup-shaped casing
1
has inlet port
31
, which sucks refrigerant gas, and outlet port
32
, which discharges compressed fluid. Outlet port
32
communicates discharge chamber
12
with the outside of the compressor.
In this structure of a scroll-type fluid displacement apparatus, when a driving force is transmitted from an external drive source, e.g., an engine of a vehicle, via drive apparatus
6
, drive shaft
3
is rotated, and orbiting scroll member
10
is driven in an orbital motion by the rotation of drive shaft
3
. When orbiting scroll member
10
moves in an orbital motion, the fluid pockets, which are formed between fixed scroll member
11
and orbiting scroll member
10
, move to the center with a consequent reduction in volume. Finally, the fluid pockets move to and are forced through discharge port
15
, and open reed valve
20
. The compressed fluid in the discharge chamber
12
is discharged into a refrigerant circuit (not shown) through outlet port
32
disposed on cup-shaped casing
1
.
Bearing member space
19
is formed around bearing
4
, which is disposed between drive shaft
3
and front housing
2
. Bearing member space
19
communicates with fluid suction space side of orbiting scroll
10
through a hole formed in housing
2
(not shown). Balance weight
26
is fixed to orbiting scroll
10
through eccentric bush
27
.
FIGS. 6
a
to
6
c
depict a plan, cross-sectional view of orbiting scroll member
10
of FIG.
5
. Conventionally, first end plate
13
of orbiting scroll member
10
is formed with a uniform plate thickness throughout. As shown in
FIG. 6
b
, in order to prevent cracks in the central end part of first spiral member
14
, however, the plate thickness of the central part of first end plate
13
tends to be thicker than the rest of end plate
13
. This is because the majority of the stress is concentrated at the collecting portion of the spiral wall of first spiral member
14
and first end plate
13
. For example, a known scroll member is disclosed in Japanese Patent Application JP-A-5-106568.
FIGS. 7
a
to
7
c
depict a plan, cross-sectional view of fixed scroll
11
member of FIG.
5
. Conventionally, second end plate
16
of fixed scroll
11
has a uniform thickness throughout.
In a known scroll-type fluid displacement apparatus, the plate thickness of the central part of first end plate
13
is thicker than the rest of end plate
13
in order to prevent cracks in the central end part of first spiral member
14
. Therefore, there are problems with the increased weight of orbiting scroll member
10
, which causes the weight of a scroll-type fluid apparatus to increase. It is difficult to reduce the weight of fixed scroll member
11
, because second end plate
16
of fixed scroll
11
is formed with a uniform thickness. Therefore, it is difficult to reduce the weight of a scroll-type fluid apparatus.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a scroll-type fluid apparatus, in which cracking in spiral members may be prevented by avoiding, or reducing, the concentration of stress in scroll members.
In an embodiment, a scroll-type fluid displacement apparatus comprises a housing and a fixed and an orbiting scroll and a driving mechanism. The housing has a fluid inlet port and a fluid outlet port. The orbiting scroll member has a first end plate and a first spiral element extending from one side of the first end plate. The fixed scroll member has a second end plate and a second spiral element extending from one side of the second end plate. The first spiral element and second spiral element interfit at an angular and a radial offset to form a plurality of line contacts defining at least one pair of sealed-off fluid pockets. The driving mechanism includes a drive shaft rotatably supported by the housing to effect the orbital motion of the orbiting scroll member by the rotation of the drive shaft to thereby change the volume of the fluid pockets. A second side of a central part of the first end plate of the orbiting scroll member has a recess portion having a plate thickness that is less than the rest of the first end plate.
In another embodiment, a scroll-type fluid displacement apparatus comprises a housing and a fixed and an orbiting scroll and a driving mechanism. The housing has a fluid inlet port and a fluid outlet port. The orbiting scroll member has a first end plate and a first spiral element extending from one side of the first end plate. The fixed scroll member has a second end plate and a second spiral element extending from one side of the second end plate. The first spiral element and second spiral element interfit at an angular and a radial offset to f
Baker & Botts L.L.P.
Denion Thomas
Sanden Corporation
Trieu Theresa
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