Defroster of refrigerant circuit and rotary compressor

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a defroster of a refrigerant circuit that uses a so-called internal intermediate pressure type two-stage compression rotary compressor, and a rotary compressor used in the refrigerant circuit.

2. Description of the Related Art

In a conventional refrigerant circuit of the aforesaid type, especially in the case of a refrigerant circuit using an internal intermediate pressure type two-stage compression rotary compressor, a refrigerant gas is introduced into a low-pressure chamber of a cylinder through a suction port of a first rotary compressing unit of the rotary compressor, and compressed into an intermediate pressure by a roller and a vane, then discharged from a high-pressure chamber of a cylinder into a hermetic vessel through the intermediary of a discharge port and a discharge muffling chamber. Further, the refrigerant gas of the intermediate pressure in the hermetic vessel is introduced into the low-pressure chamber of the cylinder through the suction port of a second rotary compressing unit, subjected to the second-stage compression by the roller and the vane to become a hot, high-pressure refrigerant gas, and introduced from the high-pressure chamber into a radiator of a gas cooler or the like constituting a refrigerant circuit through the intermediary of the discharge port and the discharge muffling chamber. In the radiator, the hot, high-pressure refrigerant gas radiates heat to effect heating action, and it is throttled by an expansion valve or a decompressor before it enters an evaporator where it absorbs heat to evaporate. After that, the cycle that begins with the suction into the first rotary compressing unit is repeated.

If a refrigerant exhibiting a large difference between high and low pressures, such as carbon dioxide (CO

2

), which is an example of carbonic acid gases, is used with such a rotary compressor, the pressure of the discharged refrigerant reaches 12 MPaG in the second rotary compressing unit wherein it obtained a high pressure, while the pressure thereof goes down to 8 MPaG in the first rotary compressing unit at a lower stage end to provide the intermediate pressure in the hermetic vessel. The suction pressure of the first rotary compressing unit is approximately 4 MPaG.

In the refrigerant circuit using such an internal intermediate pressure type two-stage compression rotary compressor, an evaporator develops frost, and the frost therefore has to be removed. To defrost the evaporator, if a hot refrigerant gas discharged from the second rotary compressing unit is supplied to the evaporator without reducing the pressure thereof by the decompressor (the hot refrigerant gas may be directly supplied to the evaporator or may be passed through the expansion valve or the decompressor without being decompressed therein (with the expansion valve fully open)), the suction pressure of the first rotary compressing unit rises, causing the discharging pressure (intermediate pressure) of the first rotary compressing unit to rise accordingly.

The refrigerant is introduced into the second rotary compressing unit and discharged, while it is not decompressed in the expansion valve. As a result, the discharging pressure of the second rotary compressing unit becomes equal to the suction pressure of the first rotary compressing unit. This leads to the reversion of the discharge pressure (high pressure) and the suction pressure (intermediate pressure) of the second rotary compressing unit.

The pressure reversion mentioned above can be prevented by eliminating the difference between the discharging pressure and the suction pressure in the second rotary compressing unit. This can be accomplished by letting the refrigerant gas of an intermediate pressure discharged from the first rotary compressing unit enter the evaporator without decompressing it, in addition to the refrigerant gas discharged from the second rotary compressing unit.

The vane is subjected to the urging force by a coil spring (a spring member) and the discharging pressure of the second rotary compressing unit as a back pressure. The vane is pressed against the roller mainly by the urging force of the coil spring (spring member) when the rotary compressor starts running, and by the back pressure after it starts running. However, if the refrigerant gases discharged from the first and second rotary compressing units are introduced into the evaporator to defrost the evaporator as described above, the back pressure for pressing the vane against the roller disappears. This leads to a problem in that only the urging force of the coil spring (spring member) remains, and causes the vane to detach from the roller, known as “vane jump”, contributing to deteriorated durability.

The vane attached to the rotary compressor is movably inserted in a slot provided in the radial direction of the cylinder, the vane being movably inserted in the radial direction of the cylinder. At the rear end of the vane (the end adjacent to the hermetic vessel), a spring hole (housing section) that opens to the outside of the cylinder is provided. The coil spring (spring member) is inserted in the spring hole, an O-ring is inserted in the spring hole from an opening in the outside of the cylinder, and the spring hole is closed by a plug (slippage stopper) thereby to prevent the spring from jumping out.

In this case, the plug is subjected to a force in the direction in which the plug is pushed out of the spring hole by the eccentric rotation of the roller. Especially in the case of an internal intermediate pressure type rotary compressor, the pressure in the hermetic vessel becomes lower than the pressure in the cylinder of the second rotary compressing unit. Hence, the difference between the inside pressure and the outside pressure of the cylinder also tends to push the plug out. For this reason, the plug has conventionally been press-fitted into the spring hole to secure it to the cylinder. This, however, has been causing a problem in that the press-fitting deforms the cylinder such that it expands, with a consequent gap between the cylinder and a supporting member or bearing that closes the opening surface of the cylinder. Thus, the air-tightness in the cylinder cannot be secured, resulting in degraded performance of the cylinder.

To solve the problem, if, for example, the outside diameter of the plug is set to be smaller than the inside diameter of the spring hole so as to prevent the deformation of the cylinder (in this case, it is necessary to make an arrangement to prevent the plug from coming off into the hermetic vessel), then the plug would be pushed toward the spring due to the intermediate pressure in the hermetic vessel when the rotary compressor stops and the pressure at the high pressure end in the cylinder drops. As a result, the spring may be crushed and the operation may fail.

As another alternative solution, if, for example, the outside diameter of the plug is set to be larger than the inside diameter of the spring hole to an extent that would not cause the cylinder to deform, then it would be difficult to determine how far the plug should be inserted into the spring hole.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made toward solving the technological problems with the prior art, and it is an object of the invention to restrain a vane from pumping when an evaporator is defrosted in a refrigerant circuit using a so-called internal intermediate pressure type two-stage compression rotary compressor, and to provide a rotary compressor capable of restraining the vane from jumping.

It is another object of the present invention to provide a rotary compressor that has a plug provided at a predetermined position to prevent a spring for urging a vane from coming off, and is capable of preventing the deformation of a cylinder.

To these ends, according one aspect of the present invention, there is provided a defroster in a refrigerant circuit including: a rotary compressor that has a hermetic vessel housing an electromotive unit and first and second rotary compressing units driven by the electromotive unit, discharges a refrigerant gas that has been compressed by the first rotary compressing unit into the hermetic vessel, and further compresses the discharged, intermediate-pressure refrigerant gas by the second rotary compressing unit; a gas cooler into which the refrigerant discharged from the second rotary compressing unit of the rotary compressor flows; a decompressor connected to the outlet end of the gas cooler; and an evaporator connected to the outlet end of the decompressor, the refrigerant from the evaporator being compressed by the first rotary compressing unit, the rotary compressor comprising a cylinder constituting the second rotary compressing unit and a roller that is fitted to an eccentric portion formed in a rotary shaft of the electromotive unit and eccentrically rotates in the cylinder, a vane abutted against the roller to partition the interior of the cylinder into a low-pressure chamber and a high-pressure chamber, a spring for constantly urging the vane toward the roller, and a back pressure chamber for applying the discharge pressure of the second rotary compressing unit to the vane as a back pressure, wherein in order to defrost the evaporator, the defroster introduces the refrigerant gas discharged from the second rotary compressing unit into the evaporator without being decompressed by the decompressor, also introduces the refrigerant gas discharged from the first rotary compressing unit into the evaporator, drives the electromotive unit of the rotary compressor at a predetermined number of revolutions, and sets the inertial force of the vane at the predetermined number of revolutions to be smaller than the urging force of the spring.

According to another aspect of the present invention, there is provided a defroster of a refrigerant circuit including: a rotary compressor that has a hermetic vessel housing an electromotive unit and first and second rotary compressing units driven by the electromotive unit, discharges a refrigerant gas that has been compressed by the first rotary compressing unit into the hermetic vessel, and further compresses the discharged, intermediate-pressure refrigerant gas by the second rotary compressing unit; a gas cooler into which the refrigerant discharged from the second rotary compressing unit of the rotary compressor flows; a decompressor connected to the outlet end of the gas cooler; and an evaporator connected to the outlet end of the decompressor, the refrigerant from the evaporator being compressed by the first rotary compressing unit, the rotary compressor comprising a cylinder constituting the second rotary compressing unit, a roller that is fitted to an eccentric portion formed in a rotary shaft of the electromotive unit and eccentrically rotates in the cylinder, a vane abutted against the roller to partition the interior of the cylinder into a low-pressure chamber and a high-pressure chamber, a spring for constantly urging the vane toward the roller, and a back pressure chamber for applying the discharge pressure of the second rotary compressing unit to the vane as a back pressure, a defroster of the refrigerant circuit that, in order to defrost the evaporator, introduces the refrigerant gas discharged from the second rotary compressing unit into the evaporator without being decompressed by the decompressor, also introduces the refrigerant gas discharged from the first rotary compressing unit into the evaporator, and drives the electromotive unit of the rotary compressor at a number of revolutions at which the inertial force of the vane is smaller than the urging force of the spring.

According to still another aspect of the present invention, there is provided a rotary compressor that includes a hermetic vessel housing an electromotive unit and first and second rotary compressing units driven by the electromotive unit, and is used in a refrigerant circuit that discharges a refrigerant gas that has been compressed by the first rotary compressing unit into the hermetic vessel, and further compresses the discharged, intermediate-pressure refrigerant gas by the second rotary compressing unit, and includes a gas cooler into which the refrigerant discharged from the second rotary compressing unit of the rotary compressor flows, a decompressor connected to the outlet end of the gas cooler, and an evaporator connected to the outlet end of the decompressor, and drives the electromotive unit at a predetermined number of revolutions and introduces the refrigerant gases discharged from the first and second rotary compressing units into the evaporator without decompressing the refrigerant gas when defrosting the evaporator, the rotary compressor including a cylinder for constituting the second rotary compressing unit and a roller that is fitted to an eccentric portion formed in a rotary shaft of the electromotive unit and eccentrically rotates in the cylinder, a vane abutted against the roller to partition the interior of the cylinder into a low-pressure chamber and a high-pressure chamber, a spring for constantly urging the vane toward the roller, and a back pressure chamber for applying the discharge pressure of the second rotary compressing unit to the vane as a back pressure, the inertial force of the vane at the number of revolutions of the electromotive unit when defrosting the evaporator being weaker than the urging force of the spring.

With this arrangement, when the evaporator is defrosted, the refrigerant gas discharged from the second rotary compressing unit and the refrigerant gas discharged from the first rotary compressing unit are introduced into the evaporator without decompressing them. Thus, the inconvenience can be prevented in which the discharge pressure and the suction pressure of the second rotary compressing unit of the rotary compressor are reversed when the evaporator is defrosted.

Especially because the inertial force of the vane at the number of revolutions of the electromotive unit in the evaporator defrosting mode becomes smaller than the urging force of the spring, the inconvenience in which the vane jumps in the second rotary compressing unit in the evaporator defrosting mode can be also avoided. This makes it possible to defrost the evaporator without adversely affecting the durability of the rotary compressor.

According to a further aspect of the present invention, there is provided a rotary compressor that includes a hermetic vessel housing an electromotive unit and first and second rotary compressing units driven by the electromotive unit, and discharges a gas that has been compressed by the first rotary compressing unit into the hermetic vessel, and further compresses the discharged, intermediate-pressure gas by the second rotary compressing unit, the rotary compressor including a cylinder for constituting the second rotary compressing unit and a roller that is fitted to an eccentric portion formed in a rotary shaft of the electromotive unit and eccentrically rotates in the cylinder, a vane abutted against the roller to partition the interior of the cylinder into a low-pressure chamber and a high-pressure chamber, a spring for constantly urging the vane toward the roller, a housing portion for the spring that is formed in the cylinder and opens toward the vane and the hermetic vessel, and a plug provided in the housing portion so that it is positioned at the hermetic vessel end of the spring to seal the housing portion, a retaining portion against which the plug abuts at a predetermined position being formed on the inner wall of the housing portion that is positioned at the spring end of the plug.

Preferably, the outside diameter of the plug of the rotary compressor is set to be larger than the inside diameter of the housing portion to an extent that will not cause the cylinder to deform when the plug is inserted in the housing portion.

Preferably, the outside diameter of the plug of the rotary compressor is set to be smaller than the inside diameter of the housing portion.

Preferably, the retaining portion of the rotary compressor is formed such that the diameter of the inner peripheral wall of the housing portion is reduced so as to form a step on the inner peripheral wall.

Thus, the rotary compressor in accordance with the present invention includes a hermetic vessel housing an electromotive unit and first and second rotary compressing units driven by the electromotive unit, and discharges a gas that has been compressed by the first rotary compressing unit into the hermetic vessel, and further compresses the discharged, intermediate-pressure gas by the second rotary compressing unit, the rotary compressor including a cylinder for constituting the second rotary compressing unit and a roller that is fitted to an eccentric portion formed in a rotary shaft of the electromotive unit and eccentrically rotates in the cylinder, a vane abutted against the roller to partition the interior of the cylinder into a low-pressure chamber and a high-pressure chamber, a spring for constantly urging the vane toward the roller, a housing portion for the spring that is formed in the cylinder and opens toward the vane and the hermetic vessel, and a plug provided in the housing portion so that it is positioned at the hermetic vessel end of the spring to seal the housing portion, a retaining portion against which the plug abuts at a predetermined position being formed on the inner wall of the housing portion that is positioned at the spring end of the plug. Thus, the retaining portion prevents the plug from moving further toward the spring.

With this arrangement, the plug can be retained at a predetermined position. Accordingly, if, for example, the outside diameter of the plug is set to be larger than the inside diameter of the housing portion to an extent that will not cause the cylinder to deform when the plug is inserted in the housing portion, then the plug can be positioned when it is press-fitted into the housing portion while preventing the cylinder from deforming due to the insertion of the plug. This improves the ease of the installation of the plug.

If, for example, the outside diameter of the plug is set to be smaller than the inside diameter of the housing portion, then it is possible to prevent the plug from being inconveniently pushed toward the spring by the intermediate pressure in the hermetic vessel when the rotary compressor stops.

Preferably, the retaining portion is formed by reducing the diameter of the inner peripheral wall of the housing portion to form a stepped portion. This permits the retaining portion to be easily formed in the housing portion of the cylinder, resulting in reduced production cost.

Preferably, the rotary compressing units in the defroster or the rotary compressor of a refrigerant circuit in accordance with the present invention effect compression by using CO

2

gas as the refrigerant.

Preferably, the defroster or the rotary compressor of the refrigerant circuit in accordance with the present invention generates warm water by using the heat radiated from the gas cooler.

Thus, marked advantages are obtained especially when the CO

2

gas is used as the refrigerant. When warm water is produced by making use of the heat from the gas cooler, it becomes possible to convey the heat of the warm water of the gas cooler to the evaporator by the refrigerant. This provides an additional advantage in that the evaporator can be defrosted more quickly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a longitudinal sectional view of a rotary compressor according to an embodiment of the present invention;

FIG. 2

is a front view of the rotary compressor shown in

FIG. 1

;

FIG. 3

is a side view of the rotary compressor shown in

FIG. 1

;

FIG. 4

is another longitudinal sectional view of the rotary compressor shown in

FIG. 1

;

FIG. 5

is still another longitudinal sectional view of the rotary compressor shown in

FIG. 1

;

FIG. 6

is a top sectional view of an electromotive unit of the rotary compressor shown in

FIG. 1

;

FIG. 7

is an enlarged sectional view of a rotary compressing mechanism of the rotary compressor shown in

FIG. 1

;

FIG. 8

is an enlarged sectional view of a vane of a second rotary compressing unit of the rotary compressor shown in

FIG. 1

;

FIG. 9

is a sectional view of a lower supporting member and a lower cover of the rotary compressor shown in

FIG. 1

;

FIG. 10

is a bottom view of the lower supporting member of the rotary compressor shown in

FIG. 1

;

FIG. 11

is a top view of an upper supporting member and an upper cover of the rotary compressor shown in

FIG. 1

;

FIG. 12

is a sectional view of the upper supporting member and the upper cover of the rotary compressor shown in

FIG. 1

;

FIG. 13

is a top view of an intermediate partitioner of the rotary compressor shown in

FIG. 1

;

FIG. 14

is a sectional view taken at the line A—A shown in

FIG. 13

;

FIG. 15

is a top view of an upper cylinder of the rotary compressor shown in

FIG. 1

;

FIG. 16

is a diagram illustrating the fluctuation in the pressure at the suction side of the upper cylinder of the rotary compressor shown in

FIG. 1

;

FIG. 17

is a sectional view illustrating the shape of the joint of a rotary shaft of the rotary compressor shown in

FIG. 1

;

FIG. 18

is a refrigerant circuit diagram of a hot-water supplying apparatus to which the present invention has been applied;

FIG. 19

is a refrigerant circuit diagram of a hot-water supplying apparatus according to another embodiment of the present invention;

FIG. 20

is a refrigerant circuit diagram of a hot-water supplying apparatus according to yet another embodiment of the present invention;

FIG. 21

is a diagram showing the maximum values of the inertial force of a vane and the maximum values of the urging force of a spring at different numbers of revolutions of the electromotive unit of the rotary compressor shown in

FIG. 1

; and

FIG. 22

is an enlarged sectional view of a plug of a second rotary compressing unit of the rotary compressor shown in FIG.

1

.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment in accordance with the present invention will now be described in conjunction with the accompanying drawings. A rotary compressor

10

shown in the drawings is an internal intermediate pressure type multi-stage compression rotary compressor that uses carbon diode (CO

2

) as its refrigerant. The rotary compressor

10

is constructed of a cylindrical hermetic vessel

12

made of a steel plate, an electromotive unit

14

disposed and accommodated at the upper side of the internal space of the hermetic vessel

12

, and a rotary compression mechanism

18

that is disposed under the electromotive unit

14

and constituted by a first rotary compressing unit

32

(1st stage) and a second rotary compressing unit

34

(2nd stage) that are driven by a rotary shaft

16

of the electromotive unit

14

. The height of the rotary compressor

10

of the embodiment is 220 mm (outside diameter being 120 mm), the height of the electromotive unit

14

is about 80 mm (the outside diameter thereof being 110 mm), and the height of the rotary compression mechanism

18

is about 70 mm (the outside diameter thereof being 110 mm). The gap between the electromotive unit

14

and the rotary compression mechanism

18

is about 5 mm. The excluded volume of the second rotary compressing unit

34

is set to be smaller than the excluded volume of the first rotary compressing unit

32

.

The hermetic vessel

12

according to this embodiment is formed of a steel plate having a thickness of 4.5 mm, and has an oil reservoir at its bottom, a vessel main body

12

A for housing the electromotive unit

14

and the rotary compression mechanism

18

, and a substantially bowl-shaped end cap (cover)

12

B for closing the upper opening of the vessel main body

12

A. A round mounting hole

12

D is formed at the center of the top surface of the end cap

12

B, and a terminal (the wire being omitted)

20

for supply power to the electromotive unit

14

is installed to the mounting hole

12

D.

In this case, the end cap

12

B surrounding the terminal

20

is provided with an annular stepped portion

12

C having a predetermined curvature that is formed by molding. The terminal

20

is constructed of a round glass portion

20

A having electrical terminals

139

penetrating it, and a metallic mounting portion

20

B formed around the glass portion

20

A and extends like a jaw aslant downward and outward. The thickness of the mounting portion

20

B is set to 2.4±0.5 mm. The terminal

20

is secured to the end cap

12

B by inserting the glass portion

20

A from below into the mounting hole

12

D to jut it out to the upper side, and abutting the mounting portion

20

B against the periphery of the mounting hole

12

D, then welding the mounting portion

20

B to the periphery of the mounting hole

12

D of the end cap

12

B.

The electromotive unit

14

is formed of a stator

22

annularly installed along the inner peripheral surface of the upper space of the hermetic vessel

12

and a rotor

24

inserted in the stator

22

with a slight gap provided therebetween. The rotor

24

is secured to the rotary shaft

16

that passes through the center thereof and extends in the perpendicular direction.

The stator

22

has a laminate

26

formed of stacked donut-shaped electromagnetic steel plates, and a stator coil

28

wound around the teeth of the laminate

26

by series winding or concentrated winding, as shown in FIG.

6

. As in the case of the stator

22

, the rotor

24

is formed also of a laminate

30

made of electromagnetic steel plates, and a permanent magnet MG is inserted in the laminate

30

.

An intermediate partitioner

36

is sandwiched between the first rotary compressing unit

32

and the second rotary compressing unit

34

. More specifically, the first rotary compressing unit

32

and the second rotary compressing unit

34

are constructed of the intermediate partitioner

36

, a cylinder

38

and a cylinder

40

disposed on and under the intermediate partitioner

36

, upper and lower rollers

46

and

48

that eccentrically rotate in the upper and lower cylinders

38

and

40

with a 180-degree phase difference by being fitted to upper and lower eccentric portions

42

and

44

provided on the rotary shaft

16

, upper and lower vanes

50

(the lower vane being not shown) that abut against the upper and lower rollers

46

and

48

to partition the interiors of the upper and lower cylinders

38

and

40

into low-pressure chambers and high-pressure chambers, as it will be discussed hereinafter, and an upper supporting member

54

and a lower supporting member

56

serving also as the bearings of the rotary shaft

16

by closing the upper open surface of the upper cylinder

38

and the bottom open surface of the lower cylinder

40

.

The upper supporting member

54

and the lower supporting member

56

are provided with suction passages

58

and

60

in communication with the interiors of the upper and lower cylinders

38

and

40

, respectively, through suction ports

161

and

162

, and recessed discharge muffling chambers

62

and

64

. The open portions of the two discharge muffling chambers

62

and

64

are closed by covers. More specifically, the discharge muffling chamber

62

is closed by an upper cover

66

, and the discharge muffling chamber

64

is closed by a lower cover

68

.

In this case, a bearing

54

A is formed upright at the center of the upper supporting member

54

, and a cylindrical bush

122

is installed to the inner surface of the bearing

54

A. Furthermore, a bearing

56

A is formed in a penetrating fashion at the center of the lower supporting member

56

. A cylindrical bush

123

is attached to the inner surface of the bearing

56

A also. These bushes

122

and

123

are made of a material exhibiting good slidability, as it will be discussed hereinafter, and the rotary shaft

16

is retained by a bearing

54

A of the upper supporting member

54

and a bearing

56

A of the lower supporting member

56

through the intermediary of the bushes

122

and

123

.

In this case, the lower cover

68

is formed of a donut-shaped round steel plate, and secured to the lower supporting member

56

from below by main bolts

129

at four points on its peripheral portion. The lower cover

68

closes the bottom open portion of the discharge muffling chamber

64

in communication with the interior of the lower cylinder

40

of the first rotary compressing unit

32

through a discharge port

41

. The distal ends of the main bolts

129

are screwed to the upper supporting members

54

. The inner periphery of the lower cover

68

projects inward beyond the inner surface of the bearing

56

A of the lower supporting member

56

so as to retain the bottom end surface of the bush

123

by the lower cover

68

to prevent it from coming off (FIG.

9

).

FIG. 10

shows the bottom surface of the lower supporting member

56

, reference numeral

128

denoting a discharge valve of the first rotary compressing unit

32

that opens and closes the discharge port

41

in the discharge muffling chamber

64

.

The lower supporting member

56

is formed of a ferrous sintered material (or castings), and its surface (lower surface) to which the lower cover

68

is attached is machined to have a flatness of 0.1 mm or less, then subjected to steaming treatment. The steaming treatment causes the ferrous surface to which the lower cover

68

is attached to an iron oxide surface, so that the pores inside the sintered material are closed, leading to improved sealing performance. This obviates the need for providing a gasket between the lower cover

68

and the lower supporting member

56

.

The discharge muffling chamber

64

and the upper cover

66

at the side adjacent to the electromotive unit

14

in the interior of the hermetic vessel

12

are in communication with each other through a communicating passage

63

, which is a hole passing through the upper and lower cylinders

38

and

40

and the intermediate partitioner

36

(FIG.

4

). In this case, an intermediate discharge pipe

121

is provided upright at the upper end of the communicating passage

63

. The intermediate discharge pipe

121

is directed to the gap between adjoining stator coils

28

and

28

wound around the stator

22

of the electromotive unit

14

located above (FIG.

6

).

The upper cover

66

closes the upper surface opening of the discharge muffling chamber

62

in communication with the interior of the upper cylinder

38

of the second rotary compressing unit

34

through a discharge port

39

, and partitions the interior of the hermetic vessel

12

to the discharge muffling chamber

62

and a chamber adjacent to the electromotive unit

14

. As shown in

FIG. 11

, the upper cover

66

has a thickness of 2 mm or more and 10 mm or less (the thickness being set to the most preferable value, 6 mm, in this embodiment), and is formed of a substantially donut-shaped, circular steel plate having a hole through which the bearing

54

A of the upper supporting member

54

penetrates. With a gasket

124

sandwiched between the upper cover

66

and the upper supporting member

54

, the peripheral portion of the upper cover

66

is secured from above to the upper supporting member

54

by four main bolts

78

through the intermediary of the gasket

124

. The distal ends of the main bolts

78

are screwed to the lower supporting member

56

.

Setting the thickness of the upper cover

66

to such a dimensional range makes it possible to achieve a reduced size, durability that is sufficiently high to survive the pressure of the discharge muffling chamber

62

that becomes higher than that of the interior of the hermetic vessel

12

, and a secured insulating distance from the electromotive unit

14

. Furthermore, an O-ring

126

is provided between the inner periphery of the upper cover

66

and the outer surface of the bearing

54

A (FIG.

12

). The O-ring

126

seals the bearing

54

A so as to provide adequate sealing at the inner periphery of the upper cover

66

. This arrangement makes it possible to prevent gas leakage, increase the volume of the discharge muffling chamber

62

, and obviate the need for installing a C-ring to secure the inner periphery of the upper cover

66

to the bearing

54

A. Reference numeral

127

shown in

FIG. 11

denotes a discharge valve of the second rotary compressing unit

34

that opens and closes the discharge port

39

in the discharge muffling chamber

62

.

The intermediate partitioner

36

that closes the lower open surface of the upper cylinder

38

and the upper open surface of the lower cylinder

40

has a through hole

131

that is located at the position corresponding to the suction side in the upper cylinder

38

and extends from the outer peripheral surface to the inner peripheral surface to establish communication between the outer peripheral surface and the inner peripheral surface thereby to constitute an oil feeding passage, as shown in

FIGS. 13 and 14

. A sealing member

132

is press-fitted to the outer peripheral surface of the through hole

131

to seal the opening in the outer peripheral surface. Furthermore, a communication hole

133

extending upward is formed in the middle of the through hole

131

.

In addition, a communication hole

134

linked to the communication hole

133

of the intermediate partitioner

36

is opened in the suction port

161

(suction side) of the upper cylinder

38

. The rotary shaft

16

has an oil hole

80

oriented perpendicularly to the axial center and horizontal oil feeding holes

82

and

84

(being also formed in the upper and lower eccentric portions

42

and

44

of the rotary shaft

16

) in communication with the oil hole

80

, as shown in FIG.

7

. The opening at the inner peripheral surface side of the through hole

131

of the intermediate partitioner

36

is in communication with the oil hole

80

through the intermediary of the oil feeding holes

82

and

84

.

As it will be discussed hereinafter, the pressure inside the hermetic vessel

12

will be an intermediate pressure, so that it will be difficult to supply oil into the upper cylinder

38

that will have a high pressure due to the second stage. However, the construction of the intermediate partitioner

36

makes it possible to draw up the oil from the oil reservoir at the bottom in the hermetic vessel

12

, lead it up through the oil hole

80

to the oil feeding holes

82

and

84

into the through hole

131

of the intermediate petitioner

36

, and supply the oil to the suction side of the upper cylinder

38

(the suction port

161

) through the communication holes

133

and

134

.

Referring now to

FIG. 16

, L denotes the changes in the pressure at the suction side of the upper cylinder

38

, and P1 denotes the pressure at the inner peripheral surface of the intermediate partitioner

36

. As indicated by L1 in the graph, the pressure, that is, the suction pressure, at the suction side of the upper cylinder

38

becomes lower than the pressure at the inner peripheral surface of the intermediate partitioner

36

due to a suction pressure loss during a suction stroke. During this period of time, oil is supplied from the through hole

131

of the intermediate partitioner

36

and the communication hole

133

into the upper cylinder

38

through the communication hole

134

of the upper cylinder

38

.

As described above, the upper and lower cylinders

38

,

40

, the intermediate partitioners

36

, the upper and lower supporting members

54

,

56

, and the upper and lower covers

66

,

68

are vertically fastened by four main bolts

78

and the main bolts

129

. Furthermore, the upper and lower cylinders

38

,

40

, the intermediate partitioner

36

, and the upper and lower supporting members

54

,

56

are fastened by auxiliary bolts

136

,

136

located outside the main bolts

78

,

129

(FIG.

4

). The auxiliary bolts

136

are inserted from the upper supporting member

54

, and the distal ends thereof are screwed to the lower supporting member

56

.

The auxiliary bolts

136

are positioned in the vicinity of a guide groove

70

(to be discussed later) of the foregoing vane

50

. The addition of the auxiliary bolts

136

,

136

to integrate the rotary compression mechanism

18

secures the sealing performance against an extremely high internal pressure. Moreover, the fastening is effected in the vicinity of the guide groove

70

of the vane

50

, thus making it possible to also prevent the leakage of the high back pressure (the pressure in a back pressure chamber

201

) applied to the vane

50

, as it will be discussed hereinafter.

The upper cylinder

38

incorporates a guide groove

70

accommodating the vane

50

, and an housing portion

70

A for housing a spring

76

positioned outside the guide groove

70

, the housing portion

70

A being opened to the guide groove

70

and the hermetic vessel

12

or the vessel main body

12

A, as shown in FIG.

8

. The spring

76

abuts against the outer end portion of the vane

50

to constantly urge the vane

50

toward the roller

46

. A metallic plug

137

is press-fitted through the opening at the outer side (adjacent to the hermetic vessel

12

) of the housing portion

70

A into the housing portion

70

A for the spring

76

at the end adjacent to the hermetic vessel

12

. The plug

137

functions to prevent the spring

76

from coming off.

In this case, the outside diameter of the plug

137

is set to value that does not cause the upper cylinder

38

to deform when the plug

137

is press-fitted into the housing portion

70

A, while the value is larger than the inside diameter of the housing portion

70

A at the same time. More specifically, in the embodiment, the outside diameter of the plug

137

is designed to be larger than the inside diameter of the housing portion

70

A by 4 μm to 23 μm. An O-ring

138

for sealing the gap between the plug

137

and the inner surface of the housing portion

70

A is attached to the peripheral surface of the plug

137

.

As shown in the enlarged view of

FIG. 22

, at the places of the housing portion

70

A where the ends (inner ends) of the plug

137

adjacent to the spring

76

, a stopper

210

are formed, against which the inner end of the plug

137

abuts when the plug

137

is press-fitted until the outer end of the plug

137

reaches a predetermined position at the opening end (the outer end of the housing portion

70

A) on the outer side (adjacent to the hermetic vessel

12

) of the housing portion

70

A. The stopper

210

is formed when the upper cylinder

38

is machine to form the housing portion

70

A. To form the stopper

210

, the inner peripheral wall of the housing portion

70

A is reduced to make a stepped portion by using a drill for machining a smaller hole for drilling the inner diameter hole of the housing portion

70

A at the inner side (adjacent to the vane

50

).

The outer end of the upper cylinder

38

, that is, the interval between the outer end of the housing portion

70

A and the vessel main body

12

A of the hermetic vessel

12

is set to be smaller than the distance from the O-ring

138

to the outer end of the plug

137

(the end adjacent to the hermetic vessel

12

). The back pressure chamber (not shown) in communication with the guide groove

70

of the vane

50

is subjected to a high pressure, as a back pressure, which is the discharge pressure of the second rotary compressing unit

34

. Hence, the end of the plug

137

adjacent to the spring

76

will have a high pressure, whereas the end thereof adjacent to the hermetic vessel

12

will have an intermediate pressure.

Establishing the aforesaid dimensional relationship between the plug

137

and the housing portion

70

A makes it possible to prevent the problem in that the upper cylinder

38

deforms due to the press-fitting of the plug

137

, and the sealing with respect to the upper supporting member

54

is deteriorated, resulting in degraded performance. Moreover, according to the construction described above, when the plug

137

is press-fitted through the opening on the outer side of the housing portion

70

A until it reaches the predetermined position (when the outer end of the plug

137

reaches the edge of the opening on the outer side of the housing portion

70

A) shown in

FIG. 22

, the plug

137

abuts against the stopper

210

and can no longer be press-fitted, so that the plug

137

can be positioned when it is press-fitted into the housing portion

70

A, permitting easier installation of the plug

137

. Especially because the danger of excessively press-fitting the plug

137

, the deformation of the upper cylinder

38

caused by forcible press-fitting can be prevented.

A coupling portion

90

for coupling the upper and lower eccentric portions

42

and

44

together that are formed integrally with the rotary shaft

16

with a 180-degree phase difference has a non-circular shape, such as a shape like a rugby ball, in order to set its sectional area larger than the round section of the rotary shaft

16

so as to secure rigidity (FIG.

17

). More specifically, the section of the coupling portion

90

for connecting the upper and lower eccentric portions

42

and

44

provided on the rotary shaft

16

is formed to increase its thickness in the direction orthogonal to the eccentric direction of the upper and lower eccentric portions

42

and

44

(refer to the hatched area in FIG.

17

).

Thus, the sectional area of the coupling portion

90

connecting the upper and lower eccentric portions

42

and

44

integrally provided on the rotary shaft

16

increases, so that the sectional secondary moment is increased to enhance the strength or rigidity, leading to higher durability and reliability. Especially when a refrigerant having a high operating pressure is compressed in two stages, the load applied to the rotary shaft

16

will be increased due to the increased difference between the high and low pressures; however, the coupling portion

90

having the larger sectional area with consequent greater strength or rigidity will be able to restrain the rotary shaft

16

from elastically deforming.

In this case, if the center of the upper eccentric portion

42

is denoted as O1, and the center of the lower eccentric portion

44

is denoted as O2, then the center of the arc of the surface of the coupling portion

90

in the eccentric direction of the eccentric portion

42

will be O1, and the center of the arc of the surface of the coupling portion

90

in the eccentric direction of the eccentric portion

44

will be O2. Thus, when chucking the rotary shaft

16

onto a cutting machine to form the upper and lower eccentric portions

42

,

44

and the coupling portion

90

, it is possible to machine the eccentric portion

42

, then to change only the radius to machine one surface of the coupling portion

90

. After that, the chucking position is changed to machine the other surface of the coupling portion

90

, and only the radius is changed to machine the eccentric portion

44

. This will reduce the number of times of re-chucking the rotary shaft

16

, and the productivity can be markedly improved.

In this case, as the refrigerant, the foregoing carbon dioxide (CO

2

), an example of carbonic acid gas, which is a natural refrigerant is used primarily because it is gentle to the earth and less flammable and toxic. For the oil functioning as a lubricant, an existing oil, such as mineral oil, alkylbenzene oil, ether oil, or ester oil is used.

On a side surface of the vessel main body

12

A of the hermetic vessel

12

, sleeves

141

,

142

,

143

, and

144

are respectively fixed by welding at the positions corresponding to the positions of the suction passages

58

and

60

of the upper supporting member

54

and the lower supporting member

56

, the discharge muffling chamber

62

, and the upper side of the upper cover

66

(the position substantially corresponding to the bottom end of the electromotive unit

14

). The sleeves

141

and

142

are vertically adjacent, and the sleeve

143

is located on a substantially diagonal line of the sleeve

141

. The sleeve

144

is located at a position shifted substantially 90 degrees from the sleeve

141

.

One end of a refrigerant introducing pipe

92

for leading a refrigerant gas into the upper cylinder

38

is inserted into the sleeve

141

, and the one end of the refrigerant introducing pipe

92

is in communication with the suction passage

58

of the upper cylinder

38

. The refrigerant introducing pipe

92

passes the upper side of the hermetic vessel

12

and reaches the sleeve

144

, and the other end thereof is inserted in and connected to the sleeve

144

to be in communication with the interior of the hermetic vessel

12

.

Furthermore, one end of a refrigerant introducing pipe

94

for leading a refrigerant gas into the lower cylinder

40

is inserted in and connected to the sleeve

142

, and the one end of the refrigerant introducing pipe

94

is in communication with the suction passage

60

of the lower cylinder

40

. The other end of the refrigerant introducing pipe

94

is connected to the bottom end of an accumulator

146

. A refrigerant discharge pipe

96

is inserted in and connected to the sleeve

143

, and one end of the refrigerant discharge pipe

96

is in communication with the discharge muffling chamber

62

.

The above accumulator

146

is a tank for separating gas from liquid of an introduced refrigerant. The accumulator

146

is installed, through the intermediary of a bracket

148

adjacent to the accumulator, to a bracket

147

adjacent to the hermetic vessel that is secured by welding to the upper side surface of the vessel main body

12

A of the hermetic vessel

12

. The bracket

148

extends upward from the bracket

147

to retain the substantially vertical central portion of the accumulator

146

. In this layout, the accumulator

146

is disposed along the side of the hermetic vessel

12

. The refrigerant introducing pipe

92

is extended out of the sleeve

141

, bent rightward in this embodiment, then routed upward. The bottom end of the accumulator

146

is adjacent to the refrigerant introducing pipe

92

. A refrigerant introducing pipe

94

directed downward from the bottom end of the accumulator

146

is routed such that it reaches the sleeve

42

, bypassing the left side, which is opposite from the bending direction of the refrigerant introducing pipe

92

as observed from the sleeve

141

(FIG.

3

).

More specifically, the refrigerant introducing pipes

92

and

94

in communication with the suction passages

58

and

60

, respectively, of the upper supporting member

38

and the lower supporting member

40

are bent in a horizontally opposite direction as observed from the hermetic vessel

12

. This arrangement restrains the refrigerant introducing pipes

92

and

94

from interfering with each other if the vertical dimension of the accumulator

146

is increased to increase the volume.

Furthermore, collars

151

with which couplers for pipe connection can be engaged are disposed around the outer surfaces of the sleeves

141

,

143

, and

144

. The inner surface of the sleeve

142

is provided with a thread groove

152

for pipe connection. This allows the couplers for test pipes to be easily connected to the collars

151

of the sleeves

141

,

143

, and

144

to carry out an airtightness test in the final inspection in the manufacturing process of the compressor

10

. In addition, the thread groove

152

allows a test pipe to be easily screwed into the sleeve

142

. Especially in the case of the vertically adjoining sleeves

141

and

142

, the sleeve

141

has the collar

151

, while the sleeve

142

has a thread groove

152

, so that test pipes can be connected to the sleeves

141

and

142

in a small space.

FIG. 18

shows a refrigerant circuit of a hot-water supplying apparatus

153

of the embodiment to which the present invention has been applied. The aforesaid rotary compressor

10

partly constitutes the refrigerant circuit of the hot-water supplying apparatus

153

shown in FIG.

18

. More specifically, the refrigerant discharge pipe

96

of the rotary compressor

10

is connected to the inlet of a gas cooler

154

that heats water to produce hot water. The gas cooler

154

is provided on a hot water storage tank (not shown) of the hot-water supplying apparatus

153

. The pipe extending out of the gas cooler

154

reaches the inlet of an evaporator

157

via an expansion valve

156

serving as a decompressing device, and the outlet of the evaporator

157

is connected to the refrigerant introducing pipe

94

. Branched off midway from the refrigerant introducing pipe

92

is a defrost pipe

158

constituting a defrosting circuit, not shown in

FIGS. 2 and 3

, and the defrost pipe

158

is connected to the refrigerant discharge pipe

96

extending to the inlet of the gas cooler

154

via a solenoid valve

159

serving as a passage controller. The accumulator

146

is not shown in FIG.

18

.

The descriptions will now be given of the operation. Reference numeral

202

denotes a controller constructed of a microcomputer in FIG.

18

. The controller

202

controls the number of revolutions of the electromotive unit

14

of the rotary compressor

10

, and also controls the solenoid valve

159

and the expansion valve

156

. For heating operation, the controller

202

closes the solenoid valve

159

. The moment the stator coil

28

of the electromotive unit

14

is energized through the intermediary of the terminal

20

and a wire (not shown) by the controller

202

, the electromotive unit

14

is started and the rotor

24

rotates. This causes the upper and lower rollers

46

and

48

fitted to the upper and lower eccentric portions

42

and

44

provided integrally with the rotary shaft

16

to eccentrically rotate in the upper and lower cylinders

38

and

40

.

Thus, a low-pressure refrigerant gas (1st-stage suction pressure LP: 4 MPaG) that has been introduced into a low-pressure chamber of the lower cylinder

40

from a suction port

162

via the refrigerant introducing pipe

94

and the suction passage

60

formed in the lower supporting member

56

is compressed by the roller

48

and the vane in operation to obtain an intermediate pressure (MP1: 8 MPaG). The refrigerant gas of the intermediate pressure leaves the high-pressure chamber of the lower cylinder

40

, passes through the discharge port

41

, the discharge muffling chamber

64

provided in the lower supporting member

56

, and the communication passage

63

, and is discharged into the hermetic vessel

12

from the intermediate discharge pipe

121

.

At this time, the intermediate discharge pipe

121

is directed toward the gap between the adjoining stator coils

28

and

28

wound around the stator

22

of the electromotive unit

14

thereabove; hence, the refrigerant gas still having a relatively low temperature can be positively supplied toward the electromotive unit

14

, thus restraining a temperature rise in the electromotive unit

14

. At the same time, the pressure inside the hermetic vessel

12

reaches the intermediate pressure (MP1).

The intermediate-pressure refrigerant gas in the hermetic vessel

12

comes out of the sleeve

144

at the above intermediate pressure (MP1), passes through the refrigerant introducing pipe

92

and the suction passage

58

formed in the upper supporting member

54

, and is drawn into the low-pressure chamber (2nd-stage suction pressure being MP2) of the upper cylinder

38

through a suction port

161

. The intermediate-pressure refrigerant gas that has been drawn in is subjected to a second-stage compression by the roller

46

and the vane

50

in operation so as to be turned into a hot high-pressure refrigerant gas (2nd-stage discharge pressure HP: 12 MPaG). The hot high-pressure refrigerant gas leaves the high-pressure chamber, passes through the discharge port

39

, the discharge muffling chamber

62

provided in the upper supporting member

54

, and the refrigerant discharge pipe

96

, and is introduced into the gas cooler

154

. The temperature of the refrigerant at this point has risen to about +100° C. the hot high-pressure refrigerant gas radiates heat from the gas cooler

154

to heat the water in the hot water storing tank to produce hot water of about +90° C.

Meanwhile, the refrigerant itself is cooled in the gas cooler

154

before it leaves the gas cooler

154

. The refrigerant is then decompressed by an expansion valve

156

, drawn into the evaporator

157

where it evaporates, absorbing heat from its surroundings, and passes through the accumulator

146

(not shown in FIG.

18

), and is introduced into the first rotary compressing unit

32

through the refrigerant introducing pipe

94

. This cycle is repeated.

Especially in an environment where the open air temperature is low, such a heating operation causes the evaporator

157

to be frosted. In this case, the controller

202

releases a solenoid valve

159

and fully opens the expansion valve

156

to defrost the evaporator

157

. This causes the intermediate-pressure refrigerant in the hermetic vessel

12

(including a small volume of the high-pressure refrigerant discharged from the second rotary compressing unit

34

) to pass through a defrosting pipe

158

and reach the gas cooler

154

. The temperature of the refrigerant ranges from about +50° C. to about +60° C., so that the refrigerant does not radiate heat in the gas cooler

154

; instead, the refrigerant absorbs heat. Then, the refrigerant leaves the gas cooler

154

, passes through the expansion valve

156

, and reaches the evaporator

157

. This means that a virtually intermediate-pressure refrigerant having a relatively high temperature is substantially directly supplied to the evaporator

157

without being decompressed, thereby heating the evaporator

157

to defrost it. At this time, the heat of hot water is conveyed from the gas cooler

154

to the evaporator

157

by the refrigerant.

When high-pressure refrigerant discharged from the second rotary compressing unit

34

is supplied to the evaporator

157

without decompressing it so as to defrost the evaporator

157

, then the suction pressure of the first rotary compressing unit

32

rises because the expansion valve

156

is fully open, resulting in an increase in the discharge pressure (intermediate pressure) of the first rotary compressing unit

32

. The refrigerant is discharged through the intermediate of the second rotary compressing unit

34

, and since the expansion valve

156

is fully open, the discharge pressure of the second rotary compressing unit

34

becomes equal to the suction pressure of the first rotary compressing unit

32

. As a result, the pressure reversion between the discharge (high pressure) of the second rotary compressing unit

34

and the suction (intermediate pressure) would take place. As described, however, the intermediate-pressure refrigerant gas discharged from the first rotary compressing unit

32

is taken out of the hermetic vessel

12

to defrost the evaporator

157

, so that the reversion between the high pressure and the intermediate pressure can be restrained.

An inertial force Fvi of the vane

50

of the second rotary compressing unit

34

is represented by expression (1) shown below:

Fvi[θ]=−mv·d

2

×[θ]/dt

2

(1)

where mv denotes the mass of the vane

50

. Therefore, the inertial force Fvi of the vane

50

is determined by the mass of the vane

50

and the number of revolutions f of the electromotive unit

14

, and the maximum value thereof increases as the number of revolutions f increases, as shown in FIG.

21

. The maximum value of an urging force (spring force) Fvs of the spring

76

remains substantially constant regardless of the number of revolutions f of the electromotive unit

14

, as shown in FIG.

21

.

Referring to

FIG. 21

, if it is assumed that, until the electromotive unit

14

reaches a number of revolutions fl, for example, the inertial force Fvi of the vane

50

is smaller than the urging force Fvs of the spring

76

, and this relationship is reversed at f1, then the controller

202

controls the number of revolutions f of the electromotive unit

14

of the rotary compressor

10

at the aforesaid f1 or less while the evaporator

157

is being defrosted.

In this case, while the evaporator

157

is being defrosted, the refrigerant gas discharged from the second rotary compressing unit

34

is introduced into the evaporator

157

without decompressing it by the expansion valve

156

as described above, and the refrigerant gas discharged from the first rotary compressing unit

32

into the hermetic vessel

12

is also introduced into the evaporator

157

. This arrangement eliminates the difference between the discharge pressure and the suction pressure of the second rotary compressing unit

34

. Hence, the back pressure from the back pressure chamber

201

is no longer applied to the vane

50

, and the urging force Fvs of the spring

76

will be the only one force that presses the vane

50

against the roller

46

.

Conventionally, if the inertial force Fvi of the vane

50

exceeds the urging force Fvs of the spring

76

, the vane

50

leaves the roller

46

, which is known as the “vane jump.”However, the controller

202

controls the number of revolutions of the electromotive unit

14

at f1 or less while the evaporator

157

is being defrosted, as described above, the inertial force Fvi of the vane

50

will not exceed the urging force Fvs of the spring

76

, thus restraining the deterioration of the durability attributable to the vane jump.

In the above embodiment, the controller

202

controls the number of revolutions of the electromotive unit

14

of the rotary compressor

10

to avoid the vane jump problem while the evaporator

157

is being defrosted. Alternatively, however, if the number of revolutions of the electromotive unit

14

for the defrosting mode is set to a predetermined value beforehand (e.g., about 100 Hz for the hot-water supplying apparatus

153

), then the material or the configuration of the vane

50

of the rotary compressor

10

may be selected or designed such that the inertial force based on the mass mv does not exceed the urging force of the spring

76

at the number of revolutions (100 Hz) in the defrosting mode. Further alternatively, the spring

76

may have an urging force that surpasses the inertial force of the vane

50

at the above number of revolutions.

FIG. 19

shows another refrigerant circuit of the hot-water supplying apparatus

153

to which the present invention has been applied. The components denoted by the same reference numerals in this figure as those shown in

FIG. 18

will have the same or equivalent functions. In this hot-water supplying apparatus

153

is provided with another defrosting pipe

158

A for establishing communication with the piping of the refrigerant discharge pipe

96

, the expansion valve

156

, and the evaporator

157

, the defrosting pipe

158

A being equipped with a solenoid valve

159

A. In this case also, the controller

202

, which is not shown in this figure, controls the rotary compressor

10

, the expansion valve

156

, and the solenoid valves

159

and

159

A.

The heating operation in the foregoing arrangement described above will be the same as that described above, because the two solenoid valves

159

and

159

A are closed. When defrosting the evaporator

157

, both solenoid valves

159

and

159

A are released. This causes the intermediate-pressure refrigerant in the hermetic vessel

12

and a small amount of the high-pressure refrigerant discharged from the second rotary compressing unit

34

to flow to the downstream side of the expansion valve

156

through the defrosting pipes

158

and

158

A, and directly reaches the evaporator

157

without being decompressed. This arrangement also prevents the pressure reversion in the second rotary compressing unit

34

.

FIG. 20

shows still another refrigerant circuit of the hot-water supplying apparatus

153

. In this refrigerant circuit also, the same reference numerals will denote the components having the same functions as those shown in FIG.

18

. In this case also, the rotary compressor

10

, the expansion valve

156

, and the solenoid valve

159

are controlled by the controller

202

, which is not shown in the figure. In this refrigerant circuit, however, the defrosting pipe

158

shown in

FIG. 18

is connected to the pipe between the expansion valve

156

and the evaporator

157

rather than the inlet of the gas cooler

154

. With this arrangement, when the solenoid valve

159

is released, the intermediate-pressure refrigerant in the hermetic vessel

12

flows to the downstream side of the expansion valve

156

and is directly introduced into the evaporator

157

without being decompressed, as in the refrigerant circuit shown in FIG.

19

. This arrangement is advantageous in that the pressure reversion of the second rotary compressing unit

34

that usually takes place in the defrosting mode can be restrained, and the number of solenoid valves can be reduced, as compared with the refrigerant circuit shown in FIG.

19

.

In the embodiments discussed above, the outside diameter of the plug

137

is set to be larger than the inside diameter of the housing portion

70

A to the extent that will not cause the upper cylinder

38

to deform, and the plug

137

is press-fitted into the housing portion

70

A. As an alternative, however, the outside diameter of the plug

137

may be set to be smaller than the inside diameter of the housing portion

70

A and the plug

137

may be gap-fitted into the housing portion

70

A.

The aforesaid dimensional relationship makes it possible to securely prevent the inconvenience in which the upper cylinder

38

deforms with consequent degraded sealing with respect to the upper supporting member

54

, leading to deteriorated performance. Such gap fitting should not cause any functional problems with the plug

138

, because the interval between the upper cylinder

38

and the hermetic vessel

12

is set to be smaller than the distance from the O-ring

138

to the end of the plug

137

that is adjacent to the hermetic vessel

12

, as discussed above. Hence, even when the plug

137

moves in the direction in which it is pushed out of the housing portion

70

A by the high pressure (the back pressure of the vane

50

) at the spring

76

side, the O-ring

138

still remains in the housing portion

70

A to maintain the sealing at the point where the plug

137

abuts against the hermetic vessel

12

and can no longer move.

When the rotary compressor

10

stops, the pressure in the upper cylinder

38

is influenced by the low pressure side through the intermediary of the refrigerant circuit, and lowers down below the intermediate pressure in the hermetic vessel

12

. In such a case, the plug

137

tends to be pushed in toward the spring

76

due to the pressure in the hermetic vessel

12

, the plug

137

abuts against the stopper

210

and cannot move any further toward the spring

76

, thus preventing the problem in that the spring

76

is crushed by the plug

137

that travels.

In the embodiments, the rotary compressor

10

has been used with the refrigerant circuit of the hot-water supplying apparatus

153

; the present invention, however, is not limited thereto. The rotary compressor

10

may alternatively be used for an indoor heater or the like.

As described in detail above, according to the present invention, when defrosting the evaporator, the refrigerant gas discharged from the second rotary compressing unit of the rotary compressor and the refrigerant gas discharged from the first rotary compressing unit are introduced into the evaporator without decompressing them. This prevents the inconvenient reversion of the discharge pressure and the suction pressure of the second rotary compressing unit of the rotary compressor when defrosting the evaporator.

Especially because the inertial force of the vane at the number of revolutions of the electromotive unit when the evaporator is defrosted is smaller than the urging force of the spring, so that the inconvenient vane jump in the second rotary compressing unit can be restrained when defrosting the evaporator. Thus, the evaporator can be defrosted without sacrificing the durability of the rotary compressor.

Moreover, according to the present invention, in a rotary compressor that has a hermetic vessel housing an electromotive unit and first and second rotary compressing units driven by the electromotive unit, discharges a gas that has been compressed by the first rotary compressing unit into the hermetic vessel, and further compresses the discharged, intermediate-pressure gas by the second rotary compressing unit, the rotary compressor including a cylinder constituting the second rotary compressing unit and a roller that is fitted to an eccentric portion formed in a rotary shaft of the electromotive unit and eccentrically rotates in the cylinder, a vane abutted against the roller to partition the interior of the cylinder into a low-pressure chamber and a high-pressure chamber, a spring for constantly urging the vane toward the roller, an housing portion for the spring that is open toward the vane and toward the hermetic vessel, and a plug that is provided in the housing portion and positioned adjacently to the hermetic vessel of the spring, and a plug for sealing the housing portion. The inner wall of the housing portion that is positioned at the spring side of the plug is provided with the stopper against which the plug abuts at a predetermined position, thereby preventing the plug from moving any further toward the spring.

With this arrangement, the plug can be accurately positioned. Accordingly, by setting the outside diameter of the plug to be larger than the inside diameter of the housing portion within the range that will not cause the cylinder to deform when the plug is inserted into the housing portion, the plug can be positioned when press-fitting it without causing the deformation of the cylinder by the insertion of the plug. This leads to easier installation of the plug.

If, for example, the outside diameter of the plug is set to be smaller than the inside diameter of the housing portion, then the inconvenience can be avoided in which the plug is pushed in toward the spring due to the intermediate pressure in the hermetic vessel when the rotary compressor stops.

The stopper is formed by reducing the diameter of the inner peripheral wall of the housing portion so as to form a stepped portion on the inner peripheral wall. This makes it possible to easily form the stopper in the housing portion of the cylinder, leading to reduced production cost.

Especially when a CO

2

gas is used as a refrigerant and the pressure difference is large, the present invention will provide marked advantages for improving the performance of the rotary compressor.

When a gas cooler is used to generate hot water, the heat of the hot water of the gas cooler can be conveyed to an evaporator by means of a refrigerant, permitting the evaporator to be defrosted more quickly.

Number	Date	Country	Kind
2001-353548	Nov 2001	JP
2001-359131	Nov 2001	JP

Number	Name	Date	Kind
6318981	Ebara et al.	Nov 2001	B1
6651458	Ebara et al.	Nov 2003	B1

Defroster of refrigerant circuit and rotary compressor

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

International Classifications

Term Extension

Abstract

Description

Claims

Priority Claims (2)

US Referenced Citations (2)