Information
-
Patent Grant
-
6641373
-
Patent Number
6,641,373
-
Date Filed
Friday, February 22, 200222 years ago
-
Date Issued
Tuesday, November 4, 200320 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Freay; Charles G.
- Solak; Timothy P.
Agents
-
CPC
-
US Classifications
Field of Search
US
- 417 310
- 417 4103
- 418 93
- 418 268
-
International Classifications
- F04B4900
- F04B1700
- F01C100
-
Abstract
To provide a gas compressor in which saving of power as well as improved compression performance and durability are attained by enabling reduction of vane back pressure without degrading the projectability of the vanes upon starting operation of the compressor. Scoop grooves and a high pressure supply hole are arranged so as to be spaced apart from each other, and the interval therebetween is set to an interval sufficient to ensure that a vane groove is communicated with neither the scoop grooves nor the high pressure supply hole while the vane groove moves apart from the scoop grooves toward the high pressure supply hole. Further, if there has occurred a reversed pressure relationship between a suction chamber (low-pressure chamber) and a discharge chamber (high-pressure chamber), a pressure control valve is actuated upon starting operation of the compressor to interconnect the scoop groove with the suction chamber side.
Description
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 passage in an opened state, whereas when the pressure in the scoop groove has risen to exceed the pressure in the suction chamber, the valve body is pushed back into close contact with the hole having a shape of a circular truncated cone due to a pressure difference to thereby set the communication passage in a closed state.
For the pressure control valve described above, there may be adopted an alternative 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 arranged 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 biasing means that constantly biases the valve body in a direction to move the valve body away from the hole having a shape of the circular truncated cone, in which when the pressure in the suction chamber becomes 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 passage in an opened state, whereas when the pressure in the scoop groove has risen to exceed the pressure in the suction chamber, the valve body is pushed back into close contact with the hole having a shape of a circular truncated cone due to a pressure difference to thereby set the communication passage in a closed state.
For the pressure control valve described above, there may be adopted an alternative 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 arranged 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; a width extending means for partially extending a width of a minute gap between the valve body and the communication passage; and a biasing means that constantly biases the valve body in a direction to move the valve body away from the hole having a shape of the circular truncated cone, in which when the pressure in the suction chamber becomes 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 passage in an opened state, whereas when the pressure in the scoop groove has risen to exceed the pressure in the suction chamber, the valve body is pushed back into close contact with the hole having a shape of a circular truncated cone due to a pressure difference to thereby set the communication passage in a closed state.
According to the present invention, the following may be adopted as constituting the width extending means: 1) means for extending the width of the minute gap in an upper region thereof, out of the entire area of the minute gap; 2) means for extending the width of the minute gap at several locations; 3) a groove formed on an inner wall of the communication passage along a direction of movement of the valve body; 4) a groove formed on an outer peripheral surface of the valve body; and so on.
According to the present invention, a biasing force applied by the biasing means may be set to be greater than an adhesive force of an oil film to adhere the valve body to the hole having a shape of a circular truncated cone.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a cross sectional view of a gas compressor according to one embodiment of the present invention.
FIG. 2
is a diagram for explaining the positional relationship between a vane groove and a scoop groove in the gas compressor shown in FIG.
1
.
FIG. 3
is an explanatory view of a pressure control valve built in the gas compressor shown in FIG.
1
.
FIG. 4
is a graph indicating the results of a comparison test of vane back pressure between the gas compressor of the present invention shown in
FIG. 1 and a
conventional gas compressor.
FIG.
5
A and
FIG. 5B
are an explanatory views showing another embodiment of the pressure control valve according to the present invention,
FIG. 5A
is a cross sectional view of the pressure control valve and
FIG. 5B
is a cross sectional view of
5
A taken along a line B—B.
FIG.
6
A and
FIG. 6B
are an explanatory views showing another embodiment of the pressure control valve according to the present invention,
FIG. 6A
is a cross sectional view of the pressure control valve and
FIG. 6B
is a cross sectional view of
6
A taken along a line B—B.
FIG.
7
A and
FIG. 7B
are an explanatory views showing another embodiment of the pressure control valve according to the present invention,
FIG. 7A
is a cross sectional view of the pressure control valve and
FIG. 7B
is a cross sectional view of
7
A taken along a line B—B.
FIG.
8
A and
FIG. 8B
are an explanatory views showing another embodiment of the pressure control valve according to the present invention,
FIG. 8A
is a cross sectional view of the pressure control valve and
FIG. 8B
is a cross sectional view of
8
A taken along a line B—B.
FIG.
9
A and
FIG. 9B
are an explanatory views showing another embodiment of the pressure control valve according to the present invention,
FIG. 9A
is cross sectional view showing an operation for opening the pressure control valve and
FIG. 9B
is cross sectional view showing an operation for closing the pressure control valve.
FIG. 10
is a cross sectional view of the conventional gas compressor.
FIG. 11
is a cross sectional view of
FIG. 10
taken along a line B—B.
FIG. 12
is a view for explaining the positional relationship between a vane groove and a scoop groove in the conventional gas compressor shown in FIG.
10
.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Hereinafter, an embodiment of a gas compressor according to the present invention will be described in detail with reference to
FIG. 1
to FIG.
9
. Note that, portions thereof that are identical to those of the conventional structure will be described using FIG.
11
.
The gas compressor of the present embodiment has a structure in which, as shown in
FIG. 1
, a compression mechanism portion
2
is accommodated in a compressor case
1
having one open end, and a front head
3
is attached to the one open end of the compressor case
1
.
The compression mechanism portion
2
includes a cylinder
4
whose inner periphery is elliptical, and side blocks
5
and
6
are attached to both end surfaces of the cylinder
4
. Also, a rotor
7
is disposed within the cylinder
4
. The rotor
7
is rotatably disposed therein by means of a rotor shaft
8
that is provided integrally with an axial center thereof, and bearings
9
and
10
of the side blocks
5
and
6
which support the rotor shaft
8
.
Turning to
FIG. 11
for further description, five slit-like vane grooves
11
are cut out on the outer peripheral surface of the rotor
7
and vanes
12
are fitted in each of these vane grooves
11
. Each of the vanes
12
slides within the vane groove
11
and is disposed in such a way as to project from the outer peripheral surface of the rotor
7
toward an inner peripheral surface of the cylinder
4
.
The interior of the cylinder
4
is partitioned into a plurality of small chambers each being defined by an inner wall of the cylinder
4
, inner surfaces of the side blocks
5
and
6
, the outer peripheral surface of the rotor
7
and both side surfaces on the tip end side of the vanes
12
. Each of the thus partitioned small chambers constitutes a compression chamber
13
. The volume of the compression chamber
13
alternately increases and decreases as the rotor
7
rotates in a direction indicated by an arrow in the drawing. Refrigerant gas in a suction chamber
14
, which is a low-pressure chamber, is thus sucked in due to the volume variations to be compressed and discharged into a discharge chamber
15
side as a high-pressure chamber.
That is, when a volume change of the compression chamber
13
occurs, low-pressure refrigerant gas in the suction chamber
14
is sucked into the compression chamber
13
during an increase phase of the volume, through a suction port of the side block
5
(not shown in the drawing), and a suction passage
4
a
in the cylinder
4
and a suction port
6
a
of the side block
6
. Then, when the volume of the compression chamber
13
starts to decrease, compression of the refrigerant within the compression chamber
13
is started due to the effect of the volume decrease. Thereafter, when the volume of the compression chamber
13
approaches the minimum volume, a reed valve
17
of a cylinder discharge hole
16
that is located near short diameter portion of the cylinder ellipse is opened due to the pressure of the compressed high-pressure refrigerant gas. Thus, the high-pressure refrigerant gas within the compression chamber
13
is discharged into a discharge chamber
18
formed in the outside of the cylinder through the cylinder discharge hole
16
, and is further introduced to the discharge chamber
15
side from the discharge chamber
18
via an oil separator
19
and the like.
Oil used for lubrication and the like is contained in a form of mist within the high-pressure refrigerant gas discharged into the discharge chamber
18
. Such oil components of the high-pressure refrigerant gas are separated and captured when the refrigerant gas passes through the oil separator
19
, and are dropped onto an oil pool
20
located at the bottom portion of the discharge chamber
15
and pooled therein.
The pressure of the high-pressure refrigerant gas that is discharged into the discharge chamber
15
acts on the oil pool
20
described above, so that oil reserved in the oil pool
20
on which this discharge pressure Pd acts is forcedly supplied to the rear-side bearing
10
through an oil hole
21
formed in the rear-side side block
6
. Then, the oil is decompressed upon passage of the clearance of the bearing
10
, and the decompressed oil flows into a rear-side scoop groove
23
to be supplied therefrom. Further, due to the pressure acting thereupon, the oil in the oil pool
20
is also forcedly supplied to the front-side bearing
9
through an oil hole
21
formed in the cylinder
4
and an oil hole
21
formed in the front-side side block
5
. Then, the oil is decompressed upon passage of the clearance of the bearing
9
, and the decompressed oil flows into a front-side scoop groove
22
to be supplied therefrom.
The rear-side scoop groove
23
is formed on a surface of the rear-side side block
6
which opposes the cylinder, whereas the front-side scoop groove
22
is formed on a surface of the front-side side block
5
which opposes the cylinder. Further, these two scoop grooves
22
,
23
are both formed so as to oppose and communicate with a bottom portion of the vane groove
11
during suction and compression of the refrigerant gas. While the bottom portion of the vane groove
11
and the scoop grooves
22
,
23
are thus being communicated with each other, low-pressure oil is supplied from the scoop grooves
22
,
23
into the bottom portion of the vane groove
11
as back pressure. Note that, in this embodiment, the shape of the scoop grooves
22
,
23
formed is a sector. The bottom portion of the vane groove
11
communicates with the scoop grooves
22
,
23
within an angular range of from θ
1
to θ
2
, with θ
1
being an angle at which a spread of the sector starts (scoop groove starting angle) and θ
2
being an angle at which the spread of the sector ends (scoop groove ending angle).
Further, a high pressure supply hole
24
is formed on a surface of the rear-side side block
6
which opposes the cylinder. The high pressure supply hole
24
is formed such that it communicates with a bottom portion of the vane groove
11
at a time immediately before discharge of the high-pressure refrigerant gas. While the bottom portion of the vane groove
11
and the high pressure supply hole
24
are thus being communicated with each other, oil having a higher pressure than that supplied to the scoop grooves
22
,
23
is supplied from the high pressure supply hole
24
into the bottom portion of the vane groove
11
as vane back pressure.
Here, as the oil having a pressure higher than that supplied from the scoop grooves
22
,
23
, oil having a pressure equivalent to the discharge pressure Pd is used. This oil having a pressure equivalent to the discharge pressure Pd is adapted to be introduced directly to the high pressure supply hole
24
from the oil hole
21
of the read-side side block
6
without passing through clearance of the bearing
10
.
As shown in
FIG. 2
, the scoop grooves
22
,
23
and the high pressure supply hole
24
are disposed independently and separately while being spaced apart from each other. The space therebetween is set to an interval sufficient to ensure that the vane groove
11
is communicated with neither the scoop grooves
22
,
23
nor the high pressure supply hole
24
while the vane groove
11
moves apart from the scoop grooves
22
,
23
toward the high pressure supply hole
24
, that is, while the suction and compression process of the refrigerant gas is being shifted to the discharge process.
As noted above, in the gas compressor according to this embodiment, while the vane groove
11
moves apart from the scoop grooves
22
,
23
toward the high pressure supply hole
24
, the vane groove
11
is communicated with neither the scoop grooves
22
,
23
nor the high pressure supply hole
24
. Therefore, it is possible to obviate the risk that high-pressure oil, that is, oil having a pressure equivalent to the discharge pressure Pd, flows from the high pressure supply hole
24
side into the scoop grooves
22
,
23
side through the vane groove
11
during a steady operation of the compressor, which in turn prevents oil pressure within the scoop grooves from rising due to the high-pressure oil thus flowing thereto and a resulting increase of the vane back pressure. Also, abrasion of the vanes
12
is lessened and power required for operating the gas compressor can be reduced as well.
Further, in the gas compressor according to this embodiment, during the suction and compression process of the refrigerant gas, only an appropriate level of vane back pressure applied by the reduced-pressure oil and centrifugal force generated due to rotation of the rotor
7
act on the vanes
12
within the vane groove
11
, thereby preventing excessive increase of force for urging the vanes
12
toward an inner wall of the cylinder
4
. Since abrasion of the vanes
12
is lessened, durability of the apparatus is also improved.
Further, in the case where the non-interconnecting structure such as described above is adopted, when the stopped position of the vane groove
11
at least one of five upon stopping the operation of the gas compressor is located between the scoop groove
22
and the high pressure supply hole
24
as shown in
FIG. 2
, the bottom portion of the vane groove
11
is communicated with neither the scoop groove
22
nor the high pressure supply hole
24
. Therefore, the vane back pressure at the bottom portion of the vane groove
11
can be maintained at a relatively high level during the stoppage of the gas compressor operation, and projectability of the vanes
12
upon restarting the operation of the gas compressor can be also improved.
Note that, when there is adopted the non-interconnecting structure described above, that is, the structure in which the high pressure supply hole
24
and scoop grooves
22
,
23
are prevented from being communicated with each other via the vane groove
11
while the vane groove
11
moves apart from the scoop grooves
22
,
23
toward the high pressure supply hole
24
, there may be a fear that the projectability of the vanes
12
at the time of starting the compressor is degraded. That case is all of vane groove
11
communicated with scoop grooves
22
,
23
when during the stoppage of the gas compressor operation. The projectability of the vanes
12
is particularly degraded if there exists a reversed relationship among the pressures in the suction chamber
14
(low-pressure chamber), the discharge chamber
15
(high-pressure chamber), and the scoop grooves
22
,
23
, that is, if the pressure in the suction chamber
14
has become higher than those in the discharge chamber
15
(high-pressure chamber) and the scoop grooves
22
,
23
. The reasons for this are as follows: 1) since increase in the oil pressure due to high-pressure oil flowing thereto does not occur not only in the steady operation of the compressor but also at the time of starting the operation thereof, the oil pressure within the scoop grooves
22
,
23
cannot readily rise upon starting the operation of the compressor; and 2) since the pressure of the refrigerant gas sucked into the compression chamber
13
from the suction chamber
14
is relatively high and this relatively high suction pressure Ps acts upon the tip of the vanes
12
, the vanes
12
are pushed back into the vane groove
11
.
Accordingly, for the purpose of improving the projectability of the vanes
12
at the time of starting the operation of the compressor, a pressure control valve
50
(FBC) is provided in the gas compressor according to this embodiment, as shown in FIG.
1
.
As shown in
FIG. 3
, the pressure control valve
50
shown in
FIG. 1
includes a communication passage
51
communicating the suction chamber
14
with the scoop groove
22
with each other, and a hole
52
having a shape of a circular truncated cone is arranged on a way of the communication passage
51
as a valve seat portion. The hole
52
having a shape of a circular truncated cone is formed such that, of both open ends thereof, a small-diameter open end
52
a
on the top portion side of the circular truncated cone is communicated with the suction chamber
14
side, and a large-diameter open end
52
b
on the bottom portion side of the circular truncated cone is communicated with the scoop groove
22
side.
There may be conceived various means for forming the communication passage
51
described above; in the pressure control valve
50
of this embodiment, a structure is adopted such that, in a through hole
53
piercing from-the suction chamber
14
to the scoop groove
22
, a cylindrical bush
54
having a length substantially equal to that of the through hole
53
is disposed and the entirety of a cylinder hollow hole
54
a
of the cylindrical bush
54
is used as the communication passage
51
. In the cylindrical bush
54
according to this structure, the cylinder hollow hole
54
a
is divided into two parts, namely a large-diameter hole
54
a
-
1
constituting a part thereof, and a small-diameter hole
54
a
-
2
constituting the front portion thereof located past the area of the large-diameter hole
54
a
-
1
. Further, the hole
52
having a shape of a circular truncated cone is formed at the bottom portion of the large-diameter hole
54
a
-
1
and a valve body
55
having a shape of a steel ball, such as a ball valve, is movably received in the large-diameter hole
54
a
-
1
.
The pressure control valve
50
shown in
FIG. 3
having the structure described above is actuated when there exists the aforementioned reversed pressure relationship at the time of starting the operation of the compressor. When the pressure control valve
50
is actuated, the scoop groove
23
and the suction chamber
14
are communicated with each other only at the time of starting the operation of the compressor.
That is, in the pressure control valve
50
shown in
FIG. 3
, when the pressure in the suction chamber
14
becomes higher than the pressures in the discharge chamber
15
and in the scoop grooves
22
,
23
, the valve body
55
is moved away from the valve seat portion, that is, the hole
52
having a shape of a circular truncated cone due to a pressure difference thus produced, whereby the communication path
51
is set in an open state. On the other hand,when the pressures in the discharge chamber
15
and the scoop grooves
22
,
23
have risen to exceed the pressure in the suction chamber
14
, the valve body
55
is pushed back into tight contact with the hole (valve seat portion)
52
having a shape of a circular truncated cone, whereby the communication passage
51
is set in a closed state.
Therefore, in the gas compressor according to this embodiment, even if there exists a reversed relationship among the pressures in the suction chamber
14
, the discharge chamber
15
, and the scoop grooves
22
,
23
at the time of starting the operation of the compressor, the pressure control valve
50
is actuated to allow a relatively high pressure to be introduced from the suction chamber
14
into the scoop groove
23
side via a communication passage
26
. Therefore, the pressure in the scoop groove
23
and the vane back pressure can readily rise, thereby attaining improved projectability of the vanes
12
at the time of starting the operation of the compressor.
FIG. 4
illustrates results of a comparison test between the vane back pressure in the gas compressor of the present invention (apparatus of the present invention) and that in the conventional gas compressor (conventional apparatus) shown in FIG.
10
. As is apparent from the results of the comparison test, it has been found that the vane back pressure can be reduced in the apparatus of the present invention as compared with the conventional apparatus.
A pressure control valve
50
shown in
FIGS. 5A
5
B may also be employed instead of the pressure control valve
50
shown in FIG.
3
.
Although a minute gap G having a size that is at least required to allow movement of the valve body
55
is formed between the valve body
55
and the communication passage
51
in each of the pressure control valves
50
shown in FIG.
3
and
FIGS. 5A
5
B, the pressure control valve
50
of
FIGS. 5A
5
B is different from the pressure control valve
50
of
FIG. 3
in that a groove
56
is formed on the inner wall of the communication passage
51
as a means for partially expanding the minute gap G. The groove
56
on the inner wall of the communication passage is formed along the direction of movement of the valve body
55
, and functions as a means for breaking off an oil film formed about the periphery of the valve body
55
.
As regards the gas compressor shown in
FIG. 1
, there may be a case where the oil that lubricates within the compressor during operation of the compressor for effecting lubrication remains within the communication passage
51
of the pressure control valve
50
even after stopping an operation of the compressor. However, when the pressure control valve
50
shown in
FIGS. 5A
5
B is adopted, a phenomenon such that the communication passage
51
of the pressure control valve
50
is blocked by a film of the residual oil becomes less likely to occur. This is because oil can readily flow out of the communication passage
51
to the outside since the groove
56
formed on the inner wall of the communication passage
51
serves as an outflow passage for the oil. When oil remains within the communication passage
51
, an oil film is formed about the periphery of the valve body
55
of the pressure control valve
50
. However, the continuity of such an oil film is broken off by means of the groove
56
formed on the inner wall of the communication passage
51
. Therefore, operational responsivity of the valve body
55
is improved, and a phenomenon such that the valve body
55
is stuck due to the oil film formed about the periphery of the valve body
55
becomes less likely to occur.
To attain the oil film breaking effect of the groove
56
, the groove
56
to be formed on the inner wall of the communication passage may be formed in a given part of the entire minute gap G between the valve body
55
and the communication passage
51
. In the pressure control valve
50
shown in
FIGS. 5A
5
B, there is adopted a structure in which the groove
56
on the inner wall of the communication passage is formed specifically in the upper region of the minute gap G as a whole. This is to minimize the possibility that the oil film breaking effect of the groove
56
wears off. That is, as regards the distribution state of oil within the entire minute gap G, the oil is more likely to remain in the lower region of the minute gap G due to its own weight. Thus, if the groove
56
on the inner wall of the communication passage is formed in the lower region of the minute gap G, the gap
56
can become filled up with the oil relatively quickly, and therefore there is a strong possibility that the oil film breaking effect of the groove
56
will wear off. On the other hand, if the groove
56
on the inner wall of the communication passage is formed in the upper region of the minute gap G, the oil is less likely to be accumulated in the groove
56
and therefore the oil film breaking effect of the groove
56
can be sustained permanently.
In the pressure control valve
50
shown in
FIGS. 5A
5
B, only one groove
56
is formed on the inner wall of the communication passage
51
as a means for partially expanding the minute gap G. However, as shown in
FIGS. 6A
6
B, a plurality of such grooves
56
may be formed radially on the inner wall of the communication passage
51
as means for expanding the minute gap G at several locations.
When there exists only one groove
56
on the inner wall of the communication passage
51
as shown in
FIG. 5A
, it is required that the groove
56
be properly arranged in the upper region of the minute gap G in order that the oil film breaking effect of the groove
56
be effectively exhibited. However, with a structure in which a plurality of the grooves
56
are formed radially on the inner wall of the communication passage
51
as shown in
FIG. 6A
, since at least one of the grooves
56
is arranged proximal to the upper region of the minute gap G, the intended function of the groove
56
, namely the oil film breaking function thereof, can be attained in a stable manner even without performing a strict control of the arrangement positions.
In the pressure control valve
50
shown in
FIGS. 3
,
5
A
5
B, and
6
A
6
B, there is adopted a structure in which almost the entirety of the communication passage is constituted by the cylindrical bush
54
. However, a structure of the communication passage
51
such as shown in
FIG. 7A
may alternatively be adopted.
That is, in a pressure control valve
50
shown in
FIGS. 7A
7
B, there is adopted a structure such that, in a through hole
53
piercing from the suction chamber
14
to the scoop groove
22
, a short cylindrical bush
54
having a length half which is about that of the through hole
53
is disposed, and the communication passage
51
is constituted of a cylinder hollow hole
54
a
of this cylindrical bush
54
and a front portion of the through hole
53
located beyond the cylindrical bush
54
. Further, in this structure of the communication passage
51
, the open end of the cylindrical bush
54
is cut out in a bowl-like shape to form a hole
52
having a shape of a circular truncated cone. Also, of both open ends
52
a
,
52
b
of the hole
52
having a circular truncated cone, a valve body
55
disposed within the communication passage
51
is located on the side of the open end
52
b
having a large diameter, and may be fitted into the hole
52
having a shape of a circular truncated cone from this position.
Also in the case of the pressure control valve
50
shown in
FIGS. 7A
7
B, a minute gap G is formed between the valve body
55
and the communication passage
51
and a groove
56
is provided as a means for partially expanding this minute gap G. Due to the aforementioned structure of the communication passage
51
, the groove
56
is formed on an inner surface of the through hole
53
in the front portion thereof past the cylindrical bush
54
. Note that, as in the aforementioned embodiments, the groove
56
is formed along the direction of movement of the valve body
55
and functions as a means for breaking off an oil film formed about the periphery of the valve body
55
.
The valve body
55
having a shape of a steel ball is adopted in the pressure control valve
50
shown in
FIGS. 3
, and
5
A
5
B to
7
A
7
B. However, a structure of the valve body
55
such as shown in
FIGS. 8A
8
B may alternatively be adopted.
A valve body
55
shown in
FIGS. 8A
8
B has a configuration such that a sealing surface of a circular cone shape is formed at the tip end portion thereof. When adopting such a valve body
55
including a sealing surface of a circular cone shape, although it is possible to form a groove
56
as width extending means on an inner wall of a communication passage
51
, the groove
56
may be formed on an outer peripheral surface of the valve body
55
as shown in
FIGS. 8A
8
B. With this structure, the width of the minute gap G can be extended by means of the groove
56
thus formed on the outer peripheral surface of the valve body
56
, thereby making it possible to attain the same effect as those obtained in the aforementioned embodiments. Moreover, there is an additional advantage such that generation of burrs, which is usually observed when performing processing to form the groove within the hole, can be obviously avoided and thus the need to perform a control with respect to foreign matters such as burrs is eliminated.
In the pressure control valve
50
shown in
FIGS. 5A
5
B through
8
A
8
B, there is adopted a structure in which the oil film formed about the periphery of the valve body
55
is broken off by means of the groove
56
(width extending means) in order to avoid occurrence of a phenomenon such that the communication passage
51
is blocked or the valve body
55
is stuck (adheres) to the hole
52
due to the oil film. However, as a measure against such sticking (adhering) phenomenon, a structure such as shown in
FIGS. 9A
9
B, for example, may be adopted in addition to the above structure.
A pressure control valve
50
shown in
FIGS. 9A
9
B is different from that shown in
FIGS. 5A
5
B and so on in that a coil spring
58
is provided as a biasing means within the communication passage
51
. This coil spring
58
is disposed within the communication passage
51
and is adapted to constantly bias the valve body
55
in a direction for moving the valve body
55
away from the hole
52
having a shape of a circular truncated cone (i.e., in a direction to open the communication passage
51
). Further, the biasing force of the coil spring
58
is set to be greater than the adhesive force of the oil film for sticking the valve body
55
to the hole
52
having a shape of a circular truncated cone.
With the pressure control valve
50
of
FIGS. 9A
9
B having the coil spring
58
as described above, if the pressure in the suction chamber
14
is lower than the pressure in the scoop groove
22
, as shown in
FIG. 9B
, due to the pressure difference between the both chambers
14
,
22
, the valve body
55
is pushed into the hole
52
having a shape of the circular truncated cone while resisting the biasing force of the coil spring
58
to thereby close the communication passage
51
. If, however, the pressure relationship between the both chambers
14
,
22
is reversed, as shown in
FIG. 9A
, due to the pressure difference between the both chambers
14
,
22
produced by the reversion of the pressures and the biasing force of the coil spring
58
, the valve body
55
is moved apart from the hole
52
having a shape of a circular truncated cone to thereby open the communication passage
51
.
Also, in the pressure control valve
50
shown in
FIGS. 9A
9
B, when the pressures in the scoop groove
22
and the suction chamber
14
are equal to each other, the valve body
55
overcomes the adhesive force of the oil film due to the biasing force of the coil spring
58
and thus moves apart from the hole
52
having a shape of a circular truncated cone. Thus, it is possible to effectively prevent a phenomenon such that the valve body
55
adheres to the hole
52
having a shape of a circular truncated cone due to the oil film when such equality between the pressures exist. Therefore, with the pressure control valve
50
shown in the drawing, when the pressure within the suction chamber
14
becomes even slightly higher than the pressure within the scoop groove
22
, the valve body
55
can quickly respond to the slight pressure reversion phenomenon to immediately equalize the pressures between the both chambers
22
,
14
.
Note that, in the pressure control valve according to the aforementioned embodiments, there is adopted a structure in which it includes either the width extending means (groove
56
) or the biasing means (coil spring
58
). However, the pressure control valve of this kind may also be constructed so as to include both the width extending means and the biasing means.
Further, although the coil spring
58
is adopted as the biasing means in the aforementioned embodiments, the biasing means of this kind is not limited to the coil spring. An elastic member having the same function as that of the coil spring may alternatively be adopted.
In the gas compressor according to the present invention, when arranging the scoop groove and the high pressure supply hole so as to be spaced apart from each other as described above, 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 while it moves apart from the scoop groove toward the high pressure supply hole side. Thus, since the vane groove is communicated with neither of the scoop groove and the high pressure supply hole while it moves apart from the scoop groove toward the high pressure supply hole, high pressure supply oil does not flow into the scoop grooves side from the high-pressure hole side through the vane groove during a steady operation of the compressor, thereby preventing an increase in the oil pressure within the scoop groove due to the high-pressure oil flowing thereto and a resulting increase in the vane back pressure. Therefore, abrasion of the vanes is lessened and thus the durability of the apparatus is improved, and the power required for operating the gas compressor of this kind is reduced (i.e., power saving is realized) and therefore saving is realized in terms of fuel consumption.
Further, in the case where the non-interconnecting structure such as described above is adopted, when the stopped position of the vane groove upon stopping the operation of the gas compressor is located between the scoop groove and the high pressure supply hole, the bottom portion of the vane groove is communicated with neither the scoop groove nor the high pressure supply hole. Thus, the vane back pressure at the bottom portion of the vane groove can be maintained at a relatively high level during the stoppage of the operation of the gas compressor. In this way, the projectability of the vanes upon starting the operation of the gas compressor can be improved also by adopting the non-interconnecting structure.
Further, in the gas compressor according to the present invention, there is provided a pressure control valve that acts to interconnect the scoop groove with the low-pressure chamber side when there exists the reversed pressure relationship between the low-pressure chamber and the high-pressure chamber as described above. Thus, even if, for example, such reversed pressure relationship exists at the time of starting the operation of the gas compressor, since the pressure control valve acts to introduce a relatively high pressure gas from the low-pressure chamber into the scoop groove through the communication passage, the pressure within the scoop groove and the vane back pressure can readily rise upon starting the operation of the compressor. Thus, projectability of the vanes upon starting the operation of the compressor is improved, and therefore there is attained enhanced starting performance of the gas compressor. Accordingly, no wasteful consumption of power occurs at the time of starting the operation of the compressor, which also contribute to savings in terms of power and fuel consumption.
Claims
- 1. 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 formed on an outer peripheral surface of the rotor and which is arranged so as to be projectable from the 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 block, the rotor, and the vanes, which alternately increases and decreases in volume as the rotor rotates, and sucks in a refrigerant gas in a low-pressure chamber due to the volume variation to compress and then discharge 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 refrigerant 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 refrigerant gas and from which a vane back pressure having a pressure higher than 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 a 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.
- 2. A gas compressor according to claim 1, wherein:the pressure control valve comprises: 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 in 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 width extending means for partially extending a width of a minute gap between the valve body and the communication passage; and when the pressure in the suction chamber has become higher than the pressure in the scoop groove, the valve body is set in the communication passage in an opened state, whereas when the pressure in the scoop groove has risen to exceed the pressure in the suction chamber, the valve body is set in the communication passage in a closed state.
- 3. A gas compressor according to claim 2, wherein the width extending means extends the width of the minute gap in an upper region thereof, out of the entire area of the minute gap.
- 4. A gas compressor according to claim 2, wherein the width extending means extends the gap of the minute gap at several locations.
- 5. A gas compressor according to claim 2, wherein the width extending means is constituted by a groove formed on an inner wall of the communication passage along a direction of movement of the valve body.
- 6. A gas compressor according to claim 2, wherein the width extending means is constituted by a groove formed on an outer peripheral surface of the valve body.
- 7. A gas compressor according to claim 1, wherein the pressure control valve comprises: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 in the communication passage; a valve body which is movably disposed within the communication passage, and which is formed such that it fits into the hole having a shape of a circular truncated cone; and biasing means that constantly biases the valve body in a direction to move the valve body away from the hole having a shape of a circular truncated cone; and when the pressure in the suction chamber has become higher than the pressure in the scoop groove, the valve body is set in the communication passage in an opened state, whereas when the pressure in the scoop groove has risen to exceed the pressure in the suction chamber, the valve body is set in the communication passage in a closed state.
- 8. A gas compressor according to claim 7, wherein a biasing force applied by the biasing means is greater than an adhesive force of an oil film that adheres the valve body to the hole having a shape of a circular truncated cone.
- 9. A gas compressor according to claim 1, wherein the pressure control valve comprises: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 in the communication passage; a valve body which is movably disposed within the communication passage, and which is formed such that it fits into the hole having a shape of a circular truncated cone; width extending means for partially extending a width of a minute gap between the valve body and the communication passage; and biasing means that constantly biases the valve body in a direction to move the valve body away from the hole having a shape of a circular truncated cone; and when the pressure in the suction chamber has become higher than the pressure in the scoop groove, the valve body is set the communication passage in an opened state, whereas when the pressure in the scoop groove has risen to exceed the pressure in the suction chamber, the valve body is set in the communication passage in a closed state.
- 10. A gas compressor according to claim 9, wherein the width extending means extends the width of the minute gap in an upper region thereof, out of the entire area of the minute gap.
- 11. A gas compressor according to claim 9, wherein the width extending means extends the gap of the minute gap at several locations.
- 12. A gas compressor according to claim 9, wherein the width extending means is constituted by a groove formed on an inner wall of the communication passage along a direction of movement of the valve body.
- 13. A gas compressor according to claim 9, wherein the width extending means is constituted by a groove formed on an outer peripheral surface of the valve body.
- 14. A gas compressor according to claim 9, wherein a biasing force applied by the biasing means is greater than an adhesive force of an oil film that adheres the valve body to the hole having a shape of a circular truncated cone.
Priority Claims (2)
Number |
Date |
Country |
Kind |
2001-055133 |
Feb 2001 |
JP |
|
2002-014726 |
Jan 2002 |
JP |
|
US Referenced Citations (8)