Prevention against shifting of tip seal of scroll compressor

A prevention against shifting of tip seal of a scroll compressor with a pair of stationary scroll and swirl scroll provided with spiral laps projectingly on an inside of end plates engaged with each other for sucking in a gas from a suction port and discharging a compressed gas from a discharge port, wherein a tip seal groove is formed on the laps provided projectingly on said pair of scrolls, a tip seal is disposed in the tip seal groove, which comprises providing a fixing means for preventing a discharge port side end portion of the tip seal disposed in said tip seal groove from shifting to a suction port side from a discharge port side along said tip seal groove, thereby preventing a leakage of a lap nose on the discharge port side.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a prevention against shifting of a tip 
seal mounted on a scroll compressor. 
2. Description of the Prior Art 
A prior art given in FIG. 10 to FIG. 12 is known as common in this kind of 
apparatus. 
In the drawings, 1 denotes a stationary scroll, 1a denotes an end plate of 
the stationary scroll 1, 1b denotes a lap formed vertically and swirlingly 
on an inside 1c of the end plate 1a, 2 denotes a swirl scroll provided 
opposite to the stationary scroll 1, 2a denotes an end plate of the swirl 
scroll 2, 2b denotes a lap formed vertically and swirlingly on an inside 
2c of the end plate 2a, and an arrangement is such that the scrolls 1, 2 
are paired to face each other, the laps 1b and 2b are then engaged with 
each other, the stationary scroll 1 is fixed on a frame 3, and the swirl 
scroll 2 is swirled on an eccentric part 4a of a crankshaft 4 or a driving 
shaft. A reference numeral 5 denotes a needle bearing, the crankshaft 4 is 
supported on bearings 6, 7 fixed on the frame 3, 8 denotes a balance 
weight mounted on the crankshaft 4, 9 denotes a suction port of air or a 
gas to compress which is provided on the stationary scroll 1, and 10 
denotes a discharge port of a compressed air. A reference numeral 11 
denotes a tip seal, which is made, for example, of an elastic material 
having a self-lubricating efficiency and formed swirlingly. A reference 
numeral 12 denotes a nose portion of the tip seal 11, 13 denotes a spiral 
tip seal groove provided on the nose portion 12 longitudinally of the laps 
1b, 2b, and the tip seal 11 is fitted in the tip seal groove 13. A 
reference character 13a denotes a bottom portion of the groove 13. 
A reference numeral 15 denotes an oil feed port for feeding oil to the 
bearings for lubrication and cooling. The frame 3 is mounted in such 
manner as will cover the scrolls 1, 2 so as not to allow a lubricting oil 
fed from the oil feed port 15 to leak externally. 
In consideration of an elongation due to thermal expansion, the tip seal 11 
is shortened by l from the length of the tip seal groove 13. A reference 
character 11a denotes a discharge port side end portion of the tip seal 
11, and 11b denotes a suction port side end portion of the tip seal 11. 
In the above-described construction, a gas pocket P working as a 
compression chamber is formed between the the laps 1b, 2b mated to face 
each other and the end plates 1a, 2a by facing the stationary scroll 1 and 
the swirl scroll 2 provided projectingly from the end plates 1a, 2a 
respectively each other, the air is sucked in from the suction port 9 by 
moving the swirl scroll 2 round a central axis of the stationary scroll 1, 
and a compressed air is discharged into the gas pocket P (FIG. 3) formed 
according as the swirl scroll 2 is moved as above from the discharge port 
10. 
In the tip seal of a prior art scroll compressor, the construction is such 
that the tip seal 11 is fitted in the nose portion 12 of the laps 1b, 2b 
of the stationary scroll 1 and the swirl scroll 2, and both the scrolls 1, 
2 are kept facing each other, then the nose portion 12 of the tip seal 11 
is pressed onto the insides 1c, 2c of the end plates 1a, 2a of both the 
scrolls 1, 2, thereby preventing leakage from the nose portion 12 of the 
laps 1b, 2b. 
However, in the prior art scroll compressor, since the tip seal 11 is kept 
shorter in length than the tip seal groove 13 in consideration of an 
elongation due to temperature rise arising according to an operation of 
the compressor, the tip seal 11 contracts due to a temperature drop or a 
discharge pressure applied on a discharge side end portion of the tip seal 
11 and moves from the side of discharge port 10 to the side of suction 
port 9 along the tip seal groove 13, thus leaving a suction side end 
portion of the tip seal crushed. Thus, the tip seal will never revert from 
the contraction despite an actuation of the compressor to temperature 
rise. Consequently, the tip seal is not present on the side of discharge 
port 10, and a sealing between the gas pocket on a high pressure side and 
the gas pocket on a low pressure side cannot be realized at a nose of the 
laps 1a, 1b. 
SUMMARY OF THE INVENTION 
The invention has been done to settle the problem pointed out as above, and 
its object is to provide a prevention against shifting of tip seal of a 
scroll compressor, which comprises a fixing means for preventing the 
discharge port side end portion of a tip seal disposed in a tip seal 
groove from shifting to a suction port side from a discharge port side 
along the tip seal groove, thereby preventing a leakage of a lap nose on 
the discharge port side. 
Now, therefore, in a prevention against shifting of tip seal of a scroll 
compressor relating to the invention, a fixing means for regulating a 
shift of the discharge port side end portion of a tip seal disposed in a 
tip seal groove formed on a lap from a discharge port side to a suction 
port side along the tip seal groove is provided, therefore a leakage of a 
lap nose on the discharge port side can be prevented to attain the 
aforementioned object. 
According to such construction, since a shift of the discharge port side 
end portion of the tip seal disposed in the tip seal groove from a 
discharge port side to a suction port side in the tip seal groove is 
regulated, a leakage of the lap nose on the discharge port side can be 
prevented effectively.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
One embodiment of a prevention against shifting of tip seal of a scroll 
compressor relating to the invention will now be described with reference 
to FIG. 1 to FIG. 4. 
Reference characters 1 to 15 represent the parts like or corresponding to 
the prior art one, for which no further description will be given 
repeatedly hereunder. 
FIG. 1 is a longitudinal sectional view of a prevention against shifting of 
tip seal of a scroll compressor which is given in one embodiment of the 
invention; FIG. 2 is a front sectional view of a scroll compressor to 
which the prevention against shifting of tip seal given in one embodiment 
of the invention is applied; FIG. 3 is a side sectional view of the 
scroll; FIG. 4 is a side view showing a state wherein the tip seal is 
disposed in a tip seal groove. 
A reference numeral 16 denotes a discharge port side end portion of the tip 
seal groove 13, and 17 denotes a suction port side end portion thereof. A 
reference numeral 18 denotes a pin for preventing the discharge port side 
end portion 11a of the tip seal 11 from shifting to a suction port side 
from a discharge port side along the tip seal groove 13 in the state where 
the tip seal 11 is disposed in the tip seal groove 13, and 19, 20 denote 
pin holes for fitting the pin 18 therein, of which the pin hole 19 is 
perforated in the tip seal 11, while the pin hole 20 is perforated in the 
bottom portion 13a of the lap 13. 
According to the above-described construction, the gas pocket working as a 
compression chamber will be constructed by the laps 1b, 2b and the insides 
1c, 2c of the end plate 1a, 2a from facing both the scrolls 1, 2 each 
other, therefore when the crank-shaft 4 is rotated, the swirl scroll 2 
revolves round a center line of the stationary scroll 1 to suck in a gas 
or air, for example, from the suction port 9, and a compressed air is 
discharged from the discharge port 10 provided at a central portion of the 
stationary scroll 1. 
In this case, temperature of both the scrolls 1, 2 rises according to a 
temperature rise of the compressed air, and the tip seal 11 disposed in 
the tip seal groove 13 formed on the laps 1b, 2b of the scrolls 1, 2 
expands on heat. The tip seal 11 contracts by temperature drop or 
discharge pressure applied on a discharge side end portion of the tip seal 
at the time of shutdown of the scroll compressor, shifts from the side of 
discharge port 10 to the side of suction port 9 along the tip seal groove, 
and thus a suction side end portion of the tip seal is left crushed. 
Consequently, the tip seal will not revert from the contraction despite 
restart-up of the compressor to temperature rise. Further, since the 
contraction of the tip seal 11 begins from the suction port side end 
portion 11b, the discharge port side end portion 11a of the tip seal 11 
shifts toward the suction port side end portion along the tip seal groove 
13. 
The tip seal 11 of this kind is made shorter in length than the tip seal 
groove 13 by an elongation l due to thermal expansion, therefore it will 
never come out of the tip seal groove 13 despite elongation due to thermal 
expansion. 
However, there takes place a clearance between the insides 1c, 2c of the 
end plates 1a, 2a of both the scrolls 1, 2 and athe bottom portion 13a of 
the tip seal groove 13 by a space whereat the nose portion 12 of the laps 
1b, 2b on the discharge port side shifts to the suction port side of the 
tip seal 11 from the discharge port side end portion 11a of the tip seal 
11 disposed in the tip seal groove 13 shifting to the suction port side 
from the discharge port side, thus allowing a compressed air of high 
pressure to leak a low-pressure side therefrom. The leakage may 
deteriorate a compression efficiency of the scroll compressor and thus is 
to exert a big influence, needless to say, on a performance of this kind 
of apparatus. 
In one embodiment of the invention, since the tip seal 11 has the pin 18 
fitted in the bottom portion 13a of the laps 1b, 2b through the pin hole 
20 perforated in the tip seal groove 13 at the discharge side end portion 
11a, the discharge port side end portion 11a of the tip seal 11 will never 
shift to the suction port side, and no clearance will result from the 
shifting, therefore a leakage at the nose portion 12 of the laps 1b, 2b 
can be prevented. 
According to the prevention against shifting of tip seal of a scroll 
compressor given in one embodiment of the invention, the tip seal is 
pinned on a bottom portion of the tip seal groove at the discharge port 
side end portion so as not to allow the discharge port side end portion of 
the tip seal disposed in the tip seal groove formed on the laps to shift 
from the discharge port side to the suction side along the tip seal 
groove, therefore the discharge port side end portion of the tip seal is 
controlled for shifting from an area on the discharge port side to the 
suction port side due to thermal contraction, force based on a pressure 
difference to work on the tip seal end portions on the discharge port side 
and the suction port side, centrifugal force due to a swirling action of 
the swirl scroll and so forth, and a leakage from a high-pressure side to 
a low-pressure side can be prevented at a lap nose on the discharge port 
side. 
According to one embodiment of the invention, furthermore, there is an 
effect ensured such that a prevention against shifting of tip seal of a 
scroll compressor may be obtained at a moderate cost through a simple 
structure. 
In one embodiment of the invention, the pin holes 19, 20 are provided on 
the tip seal and the tip seal groove respectively at the discharge port 
side end portion 11a of the tip seal 11, and the discharge port side end 
portion 11a of the tip seal 11 is fixed not to shift to the suction side 
by fitting the pin 18 slidably up and down in the pin holes 19, 20, 
however, a similar effect will be obtainable from bonding the discharge 
port side end portion 11a of the tip seal to the bottom portion 13a of the 
tip seal groove 13 as shown in FIG. 5. 
Further, instead of arranging the fixing means given in the aforementioned 
embodiment, the discharge port side end portion 11a of the tip seal 11 and 
the discharge port side end portion 16 of the tip seal groove 13 may be 
enlarged and so formed as shown in FIG. 6, or the discharge port side end 
portions 11a, 16 may be contracted partly in section and so formed as a 
deformed swelling as shown in FIG. 7 with the tip seal force fit therein. 
FIG. 8a and FIG. 8b are a side view and a longitudinal sectional view 
showing another embodiment each. As shown in the embodiment, a similar 
effect will be obtainable from locking the discharge port side end portion 
11a of the tip seal 11 on the bottom portion 13a of the tip seal groove 13 
with a screw 21 lockable in the through pin hole 20 instead of the pin 18 
in the aforementioned one embodiment. 
FIG. 9a and FIG. 9b are a side view and a longitudinal sectional view 
showing a further embodiment each. As shown in the embodiment, instead of 
the blind pin hole 20 representing another embodiment employing the 
locking means such as screw or the like including the pin in the 
aforementioned one embodiment, a pin hole 22 is perforated through in the 
tip seal 11, therefore when the tip seal 11 is disposed in the tip seal 
groove 13, first the tip seal 11 is fitted in the tip seal groove 13, and 
then the pin 18 will be inserted in the pin hole 22, thus facilitating the 
assembling work. 
Then, the tip seal is trapezoidal, semicircular or the like in section and 
hence is not necessarily limited to rectangle. Further, the tip seal may 
be inserted loosely in the tip seal groove. 
As described above, according to the invention, a prevention against 
shifting of tip seal of a scroll compressor wherein a leakage of the lap 
nose on a discharged port side is prevented and thus a performance of the 
scroll compressor can be enhanced may be provided by providing a fixing 
means so as not to allow a discharge port side end portion of the tip seal 
disposed in a tip seal groove formed on the lap to shift from the 
discharge port side to the suction port side along the tip seal groove.