Note: Descriptions are shown in the official language in which they were submitted.
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SPECIFICATION
1. TITLE OF THE INVENTION
SCROLL TYPE FLUID MACHINERY
2. FIELD OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a scroll type
fluid machinery used as a compressor, an expansion machi-
nery and the like.
A radius of revolution variable mechanism for
varying a radius of revolution in a solar motion of a
revolving scroll automatically in accordance with the
variation in gas pressure and a centrifugal force applied
to the revolving scroll of a scroll type compressor has
been disclosed in Japanese Patent Provisional Publication
No. 59-120794 (No. 120794/1984).
In this mechanism, an oscillating bearing 03
is fitted into a slide hole 02 bored on an upper end
surface of a rotary shaft 01 so as to be slidable in
a longitudinal direction but unable to rotate on its
axis, and a pin 05 projecting downward from a central
part of an underside of an end plate 04a of a revolving
scroll 04 is inserted into this oscillating bearing 03
so as to be able to rotate relatively as shown in
Fig. 5 and Fig. 6.
In Fig. 5 and Fig. 6, a spiralwrap 06b set
up on an inner surface of an end plate 06a of a stationary
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scroll 06 is engaged mutually with a spiralwrap04b set up on
an inner surface of the end plate 04a of the revolving
scroll 04 so as to delimit a compression chamber 07.
A numeral 08 denotes a frame, 09 denotes a thrust bearing
for supporting thrust acting on the revolving scroll 04,
010 denotes a bearing for supporting the upper end of
the rotary shaft 01, l denotes a shaft center of a
rotary shaft 01, 02 denotes a center of a pin 05, r
denotes eccentricity between l and 02, and a denotes
an inclination of a slide hole 02 with respect to the
direction of eccentricity.
When the rotary shaft 01 is driven to rotate
by a motor and the like not shown, the rotation is trans-
mitted to the revolving scroll 04 through the slide hole
lS 02, the oscillating bearing 03 and the pin 05. The re-
volving scroll 04 revolves in a solar motion while making
its circular orbit with eccentricity r as a radius in
a state that the rotation on its axis is checked by a
mechanism for checking the rotation on its axis not shown.
As a result, as a gas is suctioned into a compression
chamber 07 and moves toward the center of the spiral
while the compression chamber 07 is reducing the volume
thereof, the gas is compressed gradually and reaches
a central chamber 012, and is discharged therefrom through
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a discharge port 011.
A centrifugal force Fc is applied in an eccentric
direction to the revolving scroll 04 by the revolution in
a solar motion of the revolving scroll 04, and a gas force
Fg acts in a direction which meets at right angles with
the centrifugal force Fc by the gas pressure in the
compression chamber 07. A composite force F of these
centrifugal force Fc and gas force Fg is applied to the
center 2 of the pin 05.
Here, the centrifugal force Fc is expressed
by the following expression (1):
Fc = W r~2 ... (1)
where, W is the weight of the revolving scroll,
r is a radius of revolution in a solar motion
of the revolving scroll,
is a revolving angular velocity of the revolving
scroll,
g is acceleration of gravity.
The composite force F is expressed by the following expression
(2):
F = ~Fg + Fc ... (2)
An angle ~ between the direction of the composite force
F and the eccentric direction is expressed by the following
expression (3):
-- 3
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~ = tan l {Fg/Fc} ... (3)
When the composite force F is applied to the
oscillating bearing 03 through the pin 05, the oscillating
bearing 03 slides in the slide hole 02 along the longi-
tudinal direction thereof by means of a component of
force F' in the longitudinal direction of the slide hole
02 of the composite force F in the direction that the
radius of revolution r in a solar motion increases, and
thewrap04b of the revolving scroll 04 comes in contact
with thewrap06b of the stationary scroll 06 by means
of a contact pressure F".
Besides, the component of force F' of the
composite force F is expressed by the following exp-
ression (4):
F' = Fcos (~ + ~) -- (4)
The contact pressure F" is expressed by the
following expression (5):
F" = F'cos ~=Fcos(~+~) cos~ ... (5)
In above-mentioned conventional scroll type
compressor, the centrifugal force Fc acting on the re-
volving scroll 04 becomes larger in accordance with increase
of revolving angular velocity ~ of the revolving scroll
04 as it is apparent from the expression (1). Then,
when the centrifugal force Fc becomes larger, the angle
~ becomes smaller as it is apparent from the expression (3).
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, . . .
Accordingly, the component of force F' and the contact
pressure F" become larger as it is apparent from the
expressions (4) and (5).
Since the contact pressure F" becomes larger
in proportion to a square of the revolving angular
velocity ~, there has been a problem that the contact
pressure F" becomes excessive at the time of high speed
rotation of the rotary shaft 01, thus increasing wear
and noise of thewraps 04b and 06b.
3. OBJECT AND SUMMARY OF THE INVENTION
It is an object of the present invention which
has been made in view of such points to provide a scroll
type fluid machinery which solves above-mentioned problems.
It is another object of the present invention
to provide a scroll type fluid machinery in which above-
mentioned fluid machinery is improved further.
In order to achieve above-described objects,
the gist of the present invention is as described in
the following items (1) and (2), as follows.
(1) A scroll type fluid machinery in which a sta-
tionary scroll and a revolving scroll in which spiral
wraps are set up at end plates, respectively, are engaged
with each other, a drive bushing is fitted rotatably
into a boss projected at the central part of the outer
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surface of the end plate of the revolving scroll, and
a drive pin projecting from the rotary shaft is fitted
slidably into a slide hole bored in the drive bushing,
characterized in that a counter weight which generates
a centrifugal force having an opposite direction to a
centrifugal force acting on the revolving scroll at the
time of revolving motion in a solar motion thereof is
provided on the drive bushing.
Above-described construction being provided
in the present invention, the counter weight generates
a centrifugal force having an opposite direction to a
centrifugal force acting on the revolving scroll at the
time of revolving motion in a solar motion thereof. Thus,
it is possible to prevent the contact pressure between
the wrapof the revolving scroll and the wrapof the sta-
tionary scroll from becoming excessive notwithstanding
high speed rotation of the rotary shaft.
(2) A scroll type fluid machinery in which a sta-
tionary scroll and a revolving scroll in which spiral
wraps are set up at end plates, respectively, are engaged
with each other, a drive bushing is fitted rotatably
into a boss projected at the central part of the outer
surface of the end plate of the revolving scroll, and
a drive pin projecting from the rotary shaft is fitted
slidably into a slide hole bored in the drive bushing,
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characterlzed ln that a balance welght for balanclng dynamlc
unbalance caused by revolvlng motlon ln a solar motlon of the
revolvlng scroll ls provlded on the drlve bushlng, and an
axlal posltlon of the center of gravlty of the balance welght
ls made to accord wlth the axlal center of the drlve bushlng
substantlally.
Above-descrlbed constructlon belng provlded ln the
present lnventlon, lt ls posslble to prevent the contact
pressure between the wrap of the revolvlng scroll and the wrap
of the statlonary scroll from becomlng excesslve by means of
the actlon of the balance welght, and the moment lncllned
rotatlon of the drlve bushlng based on the centrlfugal force
worklng on the balance welght dlsappears or dlmlnlshes, thus
suppresslng lncllned rotatlon of the drlve bushlng.
In accordance wlth the present lnventlon there ls
provlded, a scroll type fluld machlnery comprlslng a
statlonary scroll and a revolvlng scroll havlng splral wraps
set up at end plates, respectlvely, the splral wraps belng
engaged wlth each other, a drlve bushlng belng fltted
rotatably lnto a boss pro~ected at a central part of an outer
surface of the end plate of sald revolvlng scroll, a drlve pln
pro~ectlng from a rotary shaft belng fltted slldably lnto a
sllde hole bored ln the drlve bushing, a cross sect lon of the
sllde hole havlng a notched clrcular shape and the drlve pln
havlng a notched clrcular shape correspondlng to the shape of
the sllde hole but wlth a smaller clrcumference, both the
sllde hole and drlve pin havlng generally stralght llne
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~'
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21326-167
portlons whlch mate wlth one another, and a balance welght
belng dlrectly attached to the drlve bushlng, the balance
welght balanclng dynamlc unbalance caused by revolvlng motlon
ln a solar motlon of sald revolvlng scroll, and an axlal
posltlon of the center of gravlty of sald balance welght belng
made to substantlally accord wlth the axlal center of sald
drlve bushlng to thereby reduce a moment of lncllned rotatlon
of the drlve bushlng resultlng from centrlfugal force durlng
rotatlon thereof, the generally stralght llne portlons of the
drlve pln sllde along the generally stralght llne portlons of
the sllde hole durlng rotatlon of the revolvlng scroll.
4. BRIEF DESCRIPTION OF THE DRAWINGS
Flg. 1 and Flg.2 show a flrst embodlment of the
present lnventlon, whereln Flg. 1 ls a longltudlnal sectlonal
vlew of a prlnclpal part and Flg. 2 ls a cross-sectlonal vlew
taken along a llne II-II ln Flg. 1.
Flg. 3 and Flg. 4 show a second embodlment of the
present lnventlon, whereln Flg. 3 ls a longltudlnal sectlonal
vlew of a prlnclpal part and Flg. 4 ls a front vlew ln a state
that the revolvlng scroll ls removed.
~,.
~ 7a
,.,, ~
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Fig. 5 and Fig. 6 show an example of a con-
ventional scroll type compressor, wherein Fig. 5 is a
partial longitudinal sectional view and Fig. 6 is a
cross-sectional view taken along a line VI-VI in Fig. 5.
5. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Preferred embodiments of the present invention
will be described in detail illustratively with reference
to the drawings.
The first embodiment:
Fig. 1 and Fig. 2 show first embodiment of
the present invention.
In Fig. 1 and Fig. 2, a stationary scroll 1
consists of an end plate la and a spiralwrap lb set up
on the inner surface thereof. A revolving scroll 2
consists of an end plate 2a and a spiralwrap 2b set up
on the inner surface thereof. These stationary scroll
1 and the revolving scroll 2 are made eccentric from
each other by the radius r of revolution in a solar motion
and engaged with each other as shown in the figures while
shifting the angle by 180, thereby to delimit a plurality
of compression chambers 3 to form point symmetry with
respect to the center of the spiral. A cylindrical boss
4 is projected at the central part of the outer surface
of the end plate 2a of the revolving scroll 2, and a
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drive bushing 5 is fitted rotatably into the boss 4 through
a bearing 6. A slide hole 7 is bored in the drive bushing
5, and a drive pin 9 projecting from an end surface of
a rotary shaft 8 with eccentricity by r from a shaft
center l thereof is fitted into the slide hole 7. The
section of the slide hole 7 is formed into a notched
circle obtained by notching a circle with a straight
line which is inclined in a particular direction as shown
in Fig. 2. Further, the section of the eccentric drive
pin 9 is also formed into a notched circle ~having a dia-
meter smaller than that of above-mentioned notched circle
and having a same configuration as the notched circle.
Thus, a straight line portion 9a of the drive pin 9 comes
in contact along a straight line portion 7a of the slide
hole 7, and thus, the drive pin 9 may slide therealong
and move in all directions within a range of a clearance
between the inner peripheral surface of the slide hole 7
and the outer peripheral surface of the pin 9.
Further, a counter weight 10 is attached fixedly
to the drive bushing 5, and the counter weight 10 generates
a centrifugal force in a direction opposite to that of
a centrifugal force acting on the revolving scroll 2
at the time of revolution in a solar motion thereof.
When the rotary shaft 8 is rotated, the driving
force is transmitted to the drive bushing 5 from the
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.
straight line portion 9a of the drive pin 9 through the
straight line portion 7a of the slide hole 7, and trans-
mitted further to the revolving scroll 2 through the
bearing 6 and the boss 4. Thus, the revolving scroll
2 revolves in a solar motion while making a circular
orbit with the eccentricity r as a radius and with the
shaft center l of the rotary shaft 8 as the center.
Then, the gas taken into the compression chambers 3 is
compressed gradually and reaches a central chamber I1
as the compression chambers 3 move toward the center
of the spiral while reducing volumes thereof, and is
discharged therefrom through a discharge port 12.
Now, with the revolution in a motion of the
revolving scroll 2, an unbalanced weight consisting of
the revolving scroll 2, the boss 4, the bearing 6 and
the drive bushing 5 generates a centrifugal force toward
the eccentric direction with respect to the shaft center
l of the rotary shaft 8 and the center 02 of the drive
bushing 5, but a centrifugal force in a direction opposite
to that of above-mentioned centrifugal force is generated
at the same time in the counter weight 10.
Thus, it is possible to make a force which
presses the side surface of the spiral wrap2b of the
revolving scroll 2 against the side surface of the spiral
wraplb of the stationary scroll 1, viz., the contact
-- 10 --
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,, ~
pressure constant irrespective of the number of rotation
of the rotary shaft 8.
Thus, since a counter weight which generates
a centrifugal force in a direction opposite to that of
the centrifugal force acting on the revolving scroll
at the time of revolution in a solar motion thereof is
provided on the drive bushing, it is possible to prevent
the contact pressure between the wrapof the revolving
scroll and thewrapof the stationary scroll from becoming
excessive even at the time of high speed rotation of
the rotary shaft.
As a result, abnormal wear of thewrapcan be
prevented. Therefore, it is possible to prevent lowering
of performance of a scroll type fluid machinery as well
as to extend the life thereof.
The second embodiment:
In the scroll type fluid machinery shown in
Fig. 1 of the above-described first embodiment, the axial
position of the center of gravity G of the balance weight
10 is located at a iower part in an axial direction of
the drive bushing 5, and the drive bushing 5 and the
balance weight 10 are just placed so as to slide on the
upper end surface of the rotary shaft 8 and the eccentric
drive pin 9 is just fitted into the slide hole 7 slidably.
Therefore, the balance weight 10 and the drive bushing 5
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formed in one body therewith are rotated inclining clockwise
in Fig. 1 by the centrifugal force F acting on the center
of gravity of the balance weight 10 at the time of revolution
in a solar motion of the revolving scroll 2. As a result,
there have been such problems that offset working is
produced on the rotary bearing 6 and the lower end surface
of the drive bushing 5 also works on the upper end face
of the rotary shaft 8 in an offset manner.
The present invention also provides a scroll
type fluid machinery in which above-described problems
are solved.
Fig. 3 and Fig. 4 show a second embodiment
of the present invention.
As shown in Fig. 3 and Fig. 4, the axial posi-
tion of the center of gravity G of the balance weight 10
is made to almost accord with the center in an axial
direction of the drive bushing 5 by increasing the
thickness in a vertical direction of the balance weight 10.
Other construction is almost similar to those
shown in Fig. 1 and Fig. 2, and same symbols are assigned
to corresponding members.
At the time of revolution in a solar motion
of the revolving scroll 2, the drive bushing 5 and the
balance weight 10 fixed thereto also revolves in a solar
motion with above-mentioned revolving motion, and a
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centrifugal force F acts on the balance weight 10 at
the center of gravity G. Since the axial position of
the center of gravity G is in accord with the center
in an axial direction of the drive bushing 5 substan-
tially, however, the moment of inclined rotation of the
drive bushing 5 based on the centrifugal force F dis-
appears or reduces remarkably.
In the present invention, the axial position
of the center of gravity of the balance weight is made
to accord substantially with the axial center of the
drive bushing as described above. Thus, the moment of
inclined rotation of the drive bushing based on the
centrifugal force acting on the balance weight disappears
or reduces, thus suppressing inclined rotation of the
drive bushing.
As a result, it is possible to prevent offset
working of a rotary bearing which supports the drive bush-
ing and offset working of the end surface of the drive
bushing against the end surface of the rotary shaft so
as to prevent abnormal wear and damages caused by above-
mentioned offset working, thereby to improve reliability
of a scroll type fluid machinery.
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