Pumps – With condition responsive pumped fluid control – Pressure responsive relief or bypass valve
Reexamination Certificate
2002-02-22
2003-11-04
Freay, Charles G. (Department: 3746)
Pumps
With condition responsive pumped fluid control
Pressure responsive relief or bypass valve
C417S410300, C418S268000
Reexamination Certificate
active
06641373
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a gas compressor of a vane rotary type for use in a car air conditioner system, and more particularly to a gas compressor in which vane back pressure can be reduced without degrading projectability of the vanes upon starting operation of the compressor.
2. Description of the Related Art
Conventionally, as shown in FIG.
10
and
FIG. 11
, in a gas compressor of such a vane rotary type, the interior of a cylinder
4
is partitioned into a plurality of small chambers by being defined by the cylinder
4
, side blocks
5
and
6
, a rotor
7
, and vanes
12
. Each of the thus partitioned small chambers functions as a compression chamber
13
for executing compression of a refrigerant gas.
That is, the volume of each compression chamber
13
alternately increases and decreases as the rotor
7
rotates, and a refrigerant gas in a suction chamber
14
is sucked up and compressed due to the variations in the volume and then discharged into a discharge chamber
15
side. In the course of such suction, compression, and discharge of the refrigerant gas, the vanes
12
slide within a vane groove
11
of the rotor
7
and is projected from the outer peripheral surface of the rotor
7
toward the inner peripheral surface of the cylinder
4
.
Also, during the process of suction and compression, oil having a pressure lower than a discharge pressure Pd of the refrigerant gas is supplied as vane back pressure from scoop grooves
22
,
23
of the front-side side block
5
and the rear-side side block
6
into the bottom portion of the vane groove
11
. Then, the vanes
12
is pushed onto the inner peripheral surface of the cylinder
4
due to this vane back pressure and a centrifugal force generated by the rotation of the rotor
7
.
Note that, when the process shifts from the compression of the refrigerant gas to discharge thereof, the pressure in the compression chamber
13
increases due to the pressure of the compressed refrigerant gas, and the increased pressure acts to push back the vanes
12
into the vane groove
11
so that the vanes
12
are moved away from the inner peripheral surface of the cylinder
4
. To avoid this problem, the bottom portion of the vane groove
11
communicates with a high pressure supply hole
24
of the rear-side side block
6
at a time immediately before the discharge of the refrigerant gas, and then high-pressure oil having a pressure equivalent to the discharge pressure Pd is supplied as vane back pressure from the high pressure supply hole
24
into the bottom portion of the vane groove
11
.
However, in the conventional gas compressor as described above, although the scoop grooves
22
,
23
and the high pressure supply hole
24
are arranged separately from each other, as shown in
FIG. 12
, the scoop grooves
22
,
23
and the high pressure supply hole
24
are communicated with each other via the vane groove
11
during the time when the vane groove
11
moves apart from the scoop grooves
22
,
23
toward the high pressure supply hole
24
side. Thus, high-pressure oil flows into the scoop grooves
22
,
23
side from the high pressure supply hole
24
via the vane groove
11
, and the oil pressures within the scoop grooves
22
,
23
are thus likely to increase. Therefore, the vane back pressure can readily rise upon starting the operation of the compressor, and the projectability of the vanes
12
is thus improved. However, during a steady operation of the compressor, the vane back pressure becomes excessively high, which results in such problems that not only is abrasion of the vanes
12
increased but also the power required for operating the compressor is increased.
The present invention has been made in view of the above problems, and therefore an object thereof is to provide a gas compressor in which power saving as well as improved compression performance and durability are attained by enabling reduction of the vane back pressure without degrading the projectability of the vanes upon starting the operation of the compressor.
SUMMARY OF THE INVENTION
In order to attain the above object, according to the present invention, there is provided a gas compressor comprising: a cylinder having side blocks attached to its end surface; a rotor rotatably disposed within the cylinder; vanes which slide within a vane groove that is formed on an outer peripheral surface of the rotor and which is arranged so as to be projectable from an outer peripheral surface of the rotor toward an inner peripheral surface of the cylinder; a compression chamber constituted by a small chamber that is partitioned off and defined in the interior of the cylinder by the cylinder, the side blocks, the rotor, and the vanes, which alternately increases and decreases in volume as the rotor rotates, and sucks in and compress a refrigerant gas in a low-pressure chamber due to the volume variation and then discharges it into a high-pressure chamber side; a scoop groove with which a bottom portion of the vane groove communicates during a suction and compression process of the coolant gas, and from which a vane back pressure is supplied into the bottom portion of the vane groove; a high pressure supply hole with which the bottom portion of the vane groove communicates at a time immediately before discharge of the coolant gas, and from which a vane back pressure having a pressure higher than that of the vane back pressure supplied from the scoop groove is supplied into the bottom portion of the vane groove; and a pressure control valve which interconnects the scoop groove with the low-pressure chamber side when there has occurred a reversed pressure relationship between the low-pressure chamber and the high-pressure chamber, wherein the scoop groove and the high pressure supply hole are arranged so as to be spaced apart from each other, and an interval therebetween is set to an interval sufficient to ensure that the vane groove is communicated with neither the scoop groove nor the high pressure supply hole during the time when the vane groove moves apart from the scoop groove toward the high pressure supply hole.
Therefore, since the present invention adopts the above structure, the vane groove is communicated with neither of the scoop groove and the high pressure supply hole during the time when it moves apart from the scoop groove toward the high pressure supply hole. Thus, it is possible to prevent a situation such that high-pressure oil flows into the scoop groove side from the high pressure supply hole side through the vane groove during a steady operation of the compressor. Further, when the operation of the compression is started, if there exists a reversed pressure relationship between the high-pressure chamber and the low-pressure chamber, the pressure control valve is actuated to introduce a relatively high pressure gas from the low-pressure chamber into the scoop groove side through the communication passage, thereby attaining an effect that the pressure within the scoop groove and the vane back pressure can readily rise upon starting the operation of the compressor.
According to the present invention, for the pressure control valve described above, there may be adopted a structure such that the pressure control valve includes: a communication passage communicating the suction chamber with the scoop groove; a hole having a shape of a circular truncated cone, which is arranged as a valve seat portion on a way of the communication passage; a valve body which is movably disposed within the communication passage and which is formed such that it may be fitted into the hole having a shape of a circular truncated cone; and a width extending means for partially extending a width of a minute gap between the valve body and the communication passage, in which when the pressure in the suction chamber has become higher than the pressure in the scoop groove, the valve body is moved apart from the hole having a shape of a circular truncated cone due to a pressure difference to thereby set the communication
Adams & Wilks
Freay Charles G.
Seiko Instruments Inc.
Solak Timothy P.
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