EP2050965A2

EP2050965A2 - Compressor

Info

Publication number: EP2050965A2
Application number: EP08166799A
Authority: EP
Inventors: Hajime Sato; Yoshiyuki Kimata
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Ltd
Priority date: 2007-10-19
Filing date: 2008-10-16
Publication date: 2009-04-22
Also published as: JP2009097485A; EP2050965A3; US20090104060A1

Abstract

A compressor (1) including a hermetic housing (2), a low stage-side compression mechanism (3) and a high stage-side compression mechanism (4) provided in the hermetic housing (2); and an electric motor (21) for driving the low stage-side compression mechanism (3) and the high stage-side compression mechanism (4). The low stage-side compression mechanism (3) is a rotary type compression mechanism, and the high stage-side compression mechanism (4) is a scroll type compression mechanism. The suction shutoff of the scroll type compression mechanism is accomplished when a rotor (34) of the rotary type compression mechanism is at a position (A) corresponding to the bottom dead center, at a position (B) of being rotated through 90 degrees from the bottom dead center, or between the positions (A and B).

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a compressor and, more particularly, to a technique for restraining torque fluctuations of a compressor provided with two compression mechanisms, one of a rotary type compression mechanism and the other of a scroll type compression mechanism.

Description of the Related Art

A compressor provided with two compression mechanisms, one of a rotary type compression mechanism and the other of a scroll type compression mechanism, has been proposed. For example, Japanese Patent Laid-Open No. 5-87074 discloses a two-stage compressor in which an electric motor is provided in a single hermetic housing and two compression mechanisms, each driven by the rotating shaft of the electric motor, are provided; one of these two compression mechanisms is a rotary type compression mechanism and the other is a scroll type compression mechanism; and one of the two compression mechanisms is on the low stage side and the other thereof is on the high stage side. Japanese Patent Laid-Open No. 5-87074 describes that in this two-stage compressor, the low stage-side compression mechanism is preferably of a rotary type. According to this two-stage compressor, the low stage-side compressor compresses gases from a low pressure to an intermediate pressure, and the high stage-side compressor compresses gases from the intermediate pressure to a high pressure. Therefore, the drawback of individual compressor is overcome, and a compressor small in size but high in performance can be provided as compared with the case where a rotary type compression mechanism or a scroll type compression mechanism is used singly to compress gases from a lower pressure to a high pressure.
In order to limit vibrations, it is desirable that the compressor generate small torque fluctuations. The rotary type compression mechanism generates larger torque fluctuations than the scroll type compression mechanism. Japanese Patent Laid-Open No. 5-87074 describes that, by combining the rotary type compression mechanism with the scroll type compression mechanism, the compression ratio can be decreased, so that the torque fluctuations in the rotary type compression mechanism can be reduced. However, a further reduction in torque fluctuations is desired.

SUMMARY OF THE INVENTION

The present invention aims to solve the above technical problem, and, accordingly, an object thereof is to reduce torque fluctuations of a compressor provided with two compression mechanisms, one of a rotary type compression mechanism and the other of a scroll type compression mechanism.
To achieve the above object, the inventors have studied the behavior of torque fluctuations in a rotary type compression mechanism and a scroll type compression mechanism. The study results are shown in FIGS. 12 and 13. FIG. 12 is a graph showing the relationship between the rotation angle β (abscissa) of a rotor of the rotary type compression mechanism and the torque T (ordinate), and FIG. 13 is a graph showing the relationship between the rotation angle β (abscissa) of an orbiting scroll of the scroll type compression mechanism and the torque T (ordinate). From FIGS. 12 and 13, it can be seen that the rotary type compression mechanism generates larger torque fluctuations compared with those generated by the scroll type compression mechanism. The compressor provided with two compression mechanisms, one of the rotary type compression mechanism and the other of the scroll type compression mechanism, generates torque of the sum of the torque in the rotary type compression mechanism and the torque in the scroll type compression mechanism (total torque). Therefore, torque fluctuations larger than the torque fluctuations in the rotary type compression mechanism only, may be generated in the compressor provided with two compression mechanisms. On the other hand, as shown in FIG. 13, for the scroll type compression mechanism, although there is a region in which the torque T is relatively large, there also exists a region in which the torque T is relatively small. Therefore, there is a possibility that the fluctuations in total torque can be made smaller than the torque fluctuations in the rotary type compression mechanism only. Accordingly, the inventors observed the fluctuations in total torque by variously changing the positional relationship between the rotary type compression mechanism and the scroll type compression mechanism in the direction of rotation. As a result, the inventors found that in the case where the rotary type compression mechanism and the scroll type compression mechanism have a specific positional relationship, the fluctuations in total torque can be made smaller than the torque fluctuations in the rotary type compression mechanism only.
The compressor in accordance with the present invention made based on the above-described study result includes a hermetic housing; a low stage-side compression mechanism and a high stage-side compression mechanism provided in the hermetic housing; and an electric motor for driving the low stage-side compression mechanism and the high stage-side compression mechanism, one of the low stage-side compression mechanism and the high stage-side compression mechanism being a rotary type compression mechanism, and the other thereof being a scroll type compression mechanism. In this compressor, the rotary type compression mechanism has a rotor and a blade reciprocating between the top dead center of the blade and the bottom dead center of the blade with the rotation of the rotor while the tip end of the blade is in contact with the rotor; and the suction shutoff of the scroll type compression mechanism is accomplished when the rotor is at a position A corresponding to the bottom dead center, at a position B of being rotated through 90 degrees from the position corresponding to the bottom dead center, or between the positions A and B.
Also, in the case of a two-cylinder rotary type compression mechanism, the suction shutoff of the scroll type compression mechanism is accomplished when the rotor is at a position C of being rotated through -80 degrees from the position corresponding to the bottom dead center, at a position D of being rotated through -100 degrees from the position corresponding to the bottom dead center, or between the positions C and D, or at a position E of being rotated through 80 degrees from the position corresponding to the bottom dead center, at a position F of being rotated through 100 degrees from the position corresponding to the bottom dead center, or between the positions E and F. Thereby, the fluctuations in total torque can be made small.
In the case where the low stage-side compression mechanism is configured by the rotary type compression mechanism, and the high stage-side compression mechanism is configured by the scroll type compression mechanism; and the scroll type compression mechanism has a capacity control mechanism including an exhaust port for refrigerant gas, the suction shutoff is accomplished when the exhaust port is closed by the orbiting scroll of the scroll type compression mechanism.
Torque fluctuations especially pose a problem when the compressor is operated at a low speed, that is, when the compressor is operated while using the capacity control mechanism. For this reason, in the case of the compressor having a capacity control function, the closure of the exhaust port accomplished by the orbiting scroll of the scroll type compression mechanism is regarded as the suction shutoff in the present invention.
According to the present invention, by incorporating the rotary type compression mechanism and the scroll type compression mechanism in the compressor so as to provide a specific positional relationship, the fluctuation amount of total torque can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a construction of a compressor to which the present invention is applied;
FIG. 2 is a plan view showing a construction of a low stage-side compression mechanism (rotary type compression mechanism);
FIG. 3 is a view showing an engagement state of a fixed scroll wrap and an orbiting scroll wrap at timing at which an orbiting scroll is revolved to form a closed compression chamber together with a fixed scroll;
FIGS. 4A to 4D are graphs showing the relationship between a shift angle α between blade bottom dead center and scroll suction shutoff and a torque fluctuation amount;
FIG. 5 is a graph showing the relationship between a shift angle α of 0 to 360 degrees (- 360 degrees) and a difference between the maximum value Tmax and the minimum value Tmin of total torque (Tmax - Tmin);
FIG. 6 is a schematic view showing the relationship between a rotor position and suction shutoff timing;
FIG. 7 is a sectional view showing a portion near a scroll type compression mechanism of a compressor provided with a capacity control mechanism;
FIGS. 8A and 8B are views showing an engagement state of a fixed scroll wrap and an orbiting scroll wrap in a scroll type compression mechanism of a compressor provided with a capacity control mechanism;
FIG. 9 is a sectional view showing a twin rotary type compression mechanism;
FIGS. 10A to 10D are graphs showing the relationship between a shift angle α between blade bottom dead center and scroll suction shutoff and a torque fluctuation amount in the case where a twin rotary type compression mechanism is provided;
FIG. 11 is a graph showing the relationship between a shift angle α of 0 to 360 degrees (- 360 degrees) and a difference between the maximum value Tmax and the minimum value Tmin of total torque (Tmax - Tmin) in the case where a twin rotary type compression mechanism is provided;
FIG. 12 is a graph showing the relationship between the rotation angle of a rotor of a rotary type compression mechanism and the occurring torque; and
FIG. 13 is a graph showing the relationship between the rotation angle of an orbiting scroll of a scroll type compression mechanism and the occurring torque.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will now be described in detail with reference to the accompanying drawings.
FIG. 1 is a sectional view showing the construction of a compressor 1 in this embodiment.
In the compressor 1, a low stage-side compression mechanism 3 is provided in the lower part of a hermetic housing 2, and a high stage-side compression mechanism 4 is provided in the upper part thereof. Also, in the central part of the hermetic housing 2, an electric motor 21 is provided between the low stage-side compression mechanism 3 and the high stage-side compression mechanism 4. The electric motor 21 includes a stator 22 and a rotor 23. The rotor 23 is integrally connected with a crankshaft 24. The lower end part of the crankshaft 24 forms a crankshaft 25 for the low stage-side compression mechanism 3, and the upper end part thereof forms a crankshaft 26 for the high stage-side compression mechanism 4. Also, in the bottom part of the hermetic housing 2, a predetermined amount of lubricating oil 27 is stored. The lubricating oil 27 is fed to predetermined lubrication locations of the low stage-side compression mechanism 3 and the high stage-side compression mechanism 4 via an oil feeding hole 11 formed in the axial direction of the crankshaft 24 by a positive displacement lubrication pump 28 provided in the lower end part of the crankshaft 25.
The low stage-side compression mechanism 3 is configured by a rotary type compression mechanism. As the low stage-side compression mechanism 3, a general rotary type compression mechanism is used which has a cylinder chamber 31, and includes a cylinder body 30 fixed to the hermetic housing 2, an upper bearing 32 and a lower bearing 33 provided on top of and beneath the cylinder body 30, respectively, a rotor 34 fitted in a crank part 25A of the crankshaft 25 and rotated slidingly in the cylinder chamber 31, a discharge cover 36 forming a discharge cavity 35, and a blade 38 (refer to FIG. 2) partitioning the cylinder chamber 31. As shown in FIG. 2, the blade 38 is disposed in a slit 39 formed in the cylinder body 30. The slit 39 is formed along the radial direction of the cylinder body 30 so as to have an approximately uniform width, and one end thereof is open to the cylinder chamber 31. At the other end of the slit 39, a spring S is disposed to press the blade 38 toward the rotor 34. The blade 38 reciprocates along the radial direction with the rotation of the rotor 34 while the tip end thereof is in contact with the outer periphery of the rotor 34. The state in which the tip end of the blade 38 projects farthest in the cylinder chamber 31 is referred to as a bottom dead center, and the state in which the whole of the blade 38 is present within the slit 39 is referred to as a top dead center.
In the low stage-side compression mechanism 3, refrigerant gas sucked into the cylinder chamber 31 via a suction pipe 37 connected to an accumulator, not shown, is compressed to an intermediate pressure by the rotation of the rotor 34, and then is discharged into the discharge cavity 35 and is further discharged into the hermetic housing 2 through a discharge opening provided in the discharge cover 36.
The refrigerant gas having the intermediate pressure discharged into the hermetic housing 2 flows into an upper space of the hermetic housing 2 through an air gap and the like of the electric motor 21, and is sucked into the high stage-side compression mechanism 4.
The high stage-side compression mechanism 4 is configured by a scroll type compression mechanism.
The high stage-side compression mechanism 4 includes a bearing 40 having a bearing part 41 for supporting the crankshaft 26 from the outer periphery thereof and a fixing plate 42 for fixing the bearing 40. The fixing plate 42 is fixed to the hermetic housing 2.
Also, the high stage-side compression mechanism 4 includes a fixed scroll 43 and an orbiting scroll 44 for forming a pair of compression chambers 45 by being engaged with each other with the phase being shifted, a drive bush 46 that connects the orbiting scroll 44 to a crank pin part 26A formed at the shaft end of the crankshaft 26 to revolve the orbiting scroll 44, and an Oldham's ring 47 provided between the orbiting scroll 44 and the bearing 40 to revolve the orbiting scroll 44 while preventing the rotation thereof.
Further, the high stage-side compression mechanism 4 includes a discharge valve 48 provided on the back surface of the fixed scroll 43 and a discharge cover 50 fixed on the back surface of the fixed scroll 43 to form a discharge chamber 49 between the discharge cover 50 and the fixed scroll 43.
In the high stage-side compression mechanism 4, a discharge pipe 51 is connected to the discharge chamber 49, so that the refrigerant gas having been compressed to high temperature and pressure by the procedure described below is discharged to the outside of the compressor 1.
In the high stage-side compression mechanism 4, the refrigerant gas having been compressed to the intermediate pressure by the low stage-side compression mechanism 3 and discharged into the hermetic housing 2 is sucked into the paired compression chambers 45 through a suction opening 52. The paired compression chambers 45 are moved to the center side while the volume thereof is decreased by the revolution of the orbiting scroll 44, and join together to form one compression chamber 45. During this time, the refrigerant gas is compressed from the intermediate pressure to a high pressure (discharge pressure), and is discharged into the discharge chamber 49 through a discharge port 53 formed in the central part of the fixed scroll 43. This high temperature and pressure refrigerant gas is discharged to the outside of the compressor 1 via the discharge pipe 51.
The operation of the compressor 1 constructed as described above is explained.
In the low stage-side compression mechanism 3, a refrigerant gas having a low pressure is sucked into the cylinder chamber 31 from the accumulator, not shown, via the suction pipe 37. This refrigerant gas is compressed to the intermediate pressure by the rotation of the rotor 34 made via the electric motor 21 and the crankshaft 25, and then is discharged into the discharge cavity 35. The refrigerant gas is further discharged from the discharge cavity 35 into the hermetic housing 2 through the discharge opening provided in the discharge cover 36. Thereby, the interior of the hermetic housing 2 is made to have an intermediate-pressure atmosphere, and therefore the electric motor 21 and the lubricating oil 27 are made to have a temperature equivalent to that of the intermediate-pressure refrigerant gas.
The above-mentioned intermediate-pressure refrigerant gas is sucked into the compression chambers 45 of the high stage-side compression mechanism 4 through the suction opening 52 that is open to the hermetic housing 2. In the high stage-side compression mechanism 4, the electric motor 21 is driven, and thereby the orbiting scroll 44 is revolved with respect to the fixed scroll 43 via the crankshaft 26, the crank pin part 26A, and the drive bush 46, by which the refrigerant gas is compressed. Thereby, the intermediate-pressure refrigerant gas is compressed to a high-pressure state, and is discharged into the discharge chamber 49 through the discharge valve 48.
The high temperature and pressure refrigerant gas discharged into the discharge chamber 49 is discharged from the compressor 1 through the discharge pipe 51 connected to the discharge chamber 49.
FIG. 3 is a view showing an engagement state of a wrap 43L of the fixed scroll 43 and a wrap 44L of the orbiting scroll 44 at the moment when the orbiting scroll 44 and the fixed scroll 43 form the closed compression chambers 45. Prior to this moment, the compression chambers 45 are open, so that the refrigerant gas is sucked. However, after this moment, a tip end part 43E of the fixed scroll 43 comes into contact with the outer periphery of the orbiting scroll 44, and a tip end part 44E of the orbiting scroll 44 comes into contact with the outer periphery of the fixed scroll 43, by which the suction of the refrigerant gas is stopped. This state is referred to as a suction shutoff.
The inventors determined the relationship between shift angle α and torque fluctuation amount in the compressor 1 constructed as described above. Some results are shown in FIG. 4. Herein, the shift angle α is defined as described below. When the blade 38 is in a state of bottom dead center in the rotary type compression mechanism and a suction shutoff state is formed in the scroll type compression mechanism, the shift angle α between the rotary type compression mechanism and the scroll type compression mechanism is 0 degree. Also, when suction shutoff is accomplished in the scroll type compression mechanism at a position at which the rotor 34 rotates through 90 degrees from the position corresponding to the bottom dead center, the shift angle α becomes 90 degrees.
FIGS. 4A to 4D are graphs in which the abscissas represent the rotation angle β of the rotary type compression mechanism and the scroll type compression mechanism, and the ordinates represent torque T. FIGS. 4A to 4D show results when the shift angle α is 0 degree, 90 degrees, 180 degrees, and 270 degrees, respectively. Also, in FIGS. 4A to 4D, the chain line (alternate long and short dash line) indicates the torque T of the rotary type compression mechanism only, the dotted line indicates the torque T of the scroll type compression mechanism only, and the solid line indicates the total of the torque T of the rotary type compression mechanism and the torque T of the scroll type compression mechanism.
As shown in FIGS. 4A to 4D, in both the rotary type compression mechanism and the scroll type compression mechanism, the torque T fluctuates according to the rotation angle β, and in particular, the torque of the rotary type compression mechanism fluctuates greatly. Also, from FIGS. 4A to 4D, it can be seen that the fluctuation amount of total torque differs depending on the shift angle α. Since this total torque is applied to the crankshaft 24 of the compressor 1, the torque fluctuations indicated by the solid line are required to be small. Therefore, a difference between the maximum value Tmax and the minimum value Tmin of the total torque indicated by the solid line (Tmax - Tmin) was determined in the range of the shift angle α of 0 to 360 degrees (-360 degrees). The result is shown in FIG. 5. For the rotation angle β in the rotary type compression mechanism, the position of the rotor 34 at the time when the blade 38 is at the top dead center is set at 0 degree.
From FIG. 5, it can be seen that the torque fluctuation amount can be made small in the range of the shift angle α of 0 to 90 degrees. This is because a portion in which the torque T of the rotary type compression mechanism is large and a portion in which the torque T of the scroll type compression mechanism is small, cancel each other out. Based on this result, as shown in FIG. 6, in the present invention, the rotary type compression mechanism and the scroll type compression mechanism are fixed to the crankshaft 24 (25, 26) so that the suction shutoff of scroll type compression mechanism is accomplished when the rotor 34 is at a position A corresponding to the bottom dead center of the blade 38, at a position B of being rotated through 90 degrees from the position corresponding to the bottom dead center, or between the positions A and B. By adopting this configuration, the torque fluctuation amount of the compressor 1 can be made small.
Also, by adopting this configuration, noise generated from the compressor 1 can be reduced. That is to say, in the rotary type compression mechanism, loudest noise is generated when the blade 38 comes to the top dead center (rotation angle 0 degree). This is caused by the closure of a discharge valve (not shown) of the rotary type compression mechanism. Also, in the scroll type compression mechanism, loud noise is generated at the suction shutoff time. This is because the fixed scroll 43 and the orbiting scroll 44 come into contact with each other. Therefore, if the suction shutoff is accomplished in the scroll type compression mechanism when the blade 38 comes to the top dead center in the rotary type compression mechanism, the generated noise becomes remarkable. However, in the compressor 1, the suction shutoff is not accomplished in the scroll type compression mechanism when the blade 38 comes to the top dead center in the rotary type compression mechanism. Therefore, the compressor 1 is effective in reducing noise.
Further, the discharge timing of refrigerant gas in the rotary type compression mechanism is in the range from the vicinity of 180 degrees of the rotation angle β (corresponding to the bottom dead center) to 360 degrees thereof. By adopting the above-described configuration, the scroll type compression mechanism can suck refrigerant gas discharged from the rotary type compression mechanism, so that degradation in performance caused by pressure pulsation can be restrained.
Capacity control is sometimes carried out according to the operation status of refrigeration system, air conditioner, or the like. For example, in the case of refrigeration system, in the operation status in which the refrigerated state is maintained, the load of the scroll type compression mechanism decreases considerably as compared with the operation status in which goods are cooled to a desired temperature and refrigerated. Therefore, at the time of low-load operation, capacity control is sometimes carried out. Specifically, the discharge rate from the discharge port is controlled by drawing the refrigerant gas being compressed from the compression chamber. The drawn refrigerant gas is supplied again to the suction side of the scroll type compression mechanism.
FIG. 7 is a sectional view showing a portion near the scroll type compression mechanism of a compressor 100 provided with a capacity control mechanism. Like the compressor 1, the compressor 100 includes the low stage-side compression mechanism 3 which is a rotary type compression mechanism and the like. As shown in FIG. 7, the fixed scroll 43 is formed with an exhaust port 60 for capacity control. Corresponding to this exhaust port 60, a check valve 61 is disposed on the back surface of the fixed scroll 43. At the time of capacity control, the refrigerant gas in a process of being compressed in the compression chamber 45 is exhausted via the exhaust port 60, the check valve 61, and a capacity control pipe 62. In FIG.7, the same symbols as those in FIG. 1 denote the same elements as those of the compressor 1 shown in FIG. 1.
In the case of the compressor 100 provided with the above-described capacity control function, at the time of suction shutoff in the compressor 1, since the exhaust port 60 communicates with the compression chamber 45 as shown in FIG. 8A, substantially, the suction shutoff is not achieved. When the revolution of the orbiting scroll 44 proceeds, the exhaust port 60 is closed by a wrap vertex part of the orbiting scroll 44 as shown in FIG. 8B. The suction shutoff in the compressor 100 having the capacity control function is accomplished at the moment when the exhaust port 60 is closed. Torque fluctuations pose a problem especially when the compressor 100 is operated at a low speed, that is, when the compressor 100 is operated while the capacity control is carried out. For this reason, the suction shutoff in the compressor 100 having the capacity control function is accomplished at the moment when the exhaust port 60 is closed.
As the compressor 1 shown in FIG. 1, an example in which the rotary type compression mechanism has a single cylinder (single rotary) has been shown. However, the present invention can be applied to a compressor 200 in which the rotary type compression mechanism is configured so as to have two cylinders (twin rotary) as shown in FIG. 9 and other portions are configured as those of the compressor 1 shown in FIG. 1. The twin rotary is provided with two cylinder bodies 30a and 30b, and the cylinder body 30a has a cylinder chamber 31a and the cylinder body 30b has a cylinder chamber 31b. In the cylinder chamber 31a, a rotor 34a is disposed, and in the cylinder chamber 31b, a rotor 34b is disposed. The refrigerant gas sucked into the cylinder chambers 31a and 31b via suction pipes 37a and 37b connected to the accumulator, respectively, is compressed by the rotations of the rotors 34a and 34b. A mechanism having the cylinder body 30a is referred to as a first rotary, and a mechanism having the cylinder body 30b is referred to as a second rotary. The same symbols as those in FIG. 1 denote the same elements as those of the compressor 1 shown in FIG. 1.
Although not shown in the figure, the blade 38 is disposed in both the first rotary and the second rotary. When the blade of the first rotary is at the bottom dead center, the blade of the second rotary is at the top dead center. Also, when the blade of the first rotary is at the top dead center, the blade of the second rotary is at the bottom dead center. That is, the blades of the first rotary and the second rotary are 180 degrees out of phase.
For the compressor 200 provided with the first rotary and the second rotary as described above, the relationship between the shift angle α and the torque fluctuations has been determined. The results are shown in FIG. 10. FIGS. 10A to 10D are graphs in which the abscissas represent the rotation angle β of the rotary type compression mechanism and the scroll type compression mechanism, and the ordinates represent torque T. FIGS. 10A to 10D show results when the shift angle α is 0 degree, 90 degrees, 180 degrees, and 270 degrees, respectively. Also, in FIGS. 10A to 10D, the chain line (alternate long and short dash line) indicates the torque T of the rotary type compression mechanism (twin rotary) only, the dotted line indicates the torque T of the scroll type compression mechanism only, and the solid line indicates the total of the torque T of the rotary type compression mechanism and the torque T of the scroll type compression mechanism.
From FIGS. 10A to 10D, it can be seen that the fluctuation amount of total torque differs depending on the shift angle α. Therefore, a difference between the maximum value Tmax and the minimum value Tmin of the total torque indicated by the solid line (Tmax - Tmin) was determined in the range of the shift angle α of 0 to 360 degrees (-360 degrees). The result is shown in FIG. 11.
As shown in FIG. 11, at the shift angle α of -80 degrees to -100 degrees or 80 degrees to 100 degrees, the torque difference Tmax - Tmin is small. Therefore, in the case of the twin rotary, the rotary type compression mechanism and the scroll type compression mechanism are fixed to the crankshaft 24 (25, 26) so that the suction shutoff of scroll type compression mechanism is accomplished when the rotor is at a position C of being rotated through -80 degrees from the position corresponding to the bottom dead center, at a position D of being rotated through -100 degrees from the position corresponding to the bottom dead center, or between the positions C and D, or at a position E of being rotated through 80 degrees from the position corresponding to the bottom dead center, at a position F of being rotated through 100 degrees from the position corresponding to the bottom dead center, or between the positions E and F.
The above is an explanation of the embodiment of the present invention. The present invention is not limited to the above-described embodiment, and changes can be made appropriately without departing from the spirit and scope of the present invention. For example, in the above-described embodiment, a rotary type compression mechanism is used as the low stage-side compression mechanism 3, and a scroll type compression mechanism is used as the high stage-side compression mechanism 4. However, this configuration can be reversed.

Claims

A compressor comprising:
a hermetic housing (2);

a low stage-side compression mechanism (3) and a high stage-side compression mechanism (4) provided in the hermetic housing (2); and

an electric motor (21) for driving the low stage-side compression mechanism (3) and the high stage-side compression mechanism (4),

one of the low stage-side compression mechanism (3) and the high stage-side compression mechanism (4) being a rotary type compression mechanism, and the other thereof being a scroll type compression mechanism, characterized in that

the rotary type compression mechanism has a rotor (34) and a blade (38) reciprocating between a top dead center of the blade and a bottom dead center of the blade with the rotation of the rotor while the tip end thereof is in contact with the rotor; and

a suction shutoff of the scroll type compression mechanism is accomplished when the rotor (34) is at a position A corresponding to the bottom dead center, at a position B of being rotated through 90 degrees from the position corresponding to the bottom dead center, or between the positions A and B.
The compressor according to claim 1, wherein
the rotary type compression mechanism has a single cylinder.
The compressor according to claim 1 or 2, wherein
the low stage-side compression mechanism (3) is configured by the rotary type compression mechanism, and

the high stage-side compression mechanism (4) is configured by the scroll type compression mechanism.
The compressor according to claim 3, wherein
the scroll type compression mechanism has a capacity control mechanism including an exhaust port (60) for refrigerant gas, and

the suction shutoff is accomplished when the exhaust port (60) is closed by an orbiting scroll (44) of the scroll type compression mechanism.
The compressor according to claim 4, wherein
the capacity control mechanism includes at least two exhaust ports.
A compressor comprising:
a hermetic housing (2);

a low stage-side compression mechanism (3) and a high stage-side compression mechanism (4) provided in the hermetic housing (2); and

an electric motor (21) for driving the low stage-side compression mechanism (3) and the high stage-side compression mechanism (4),

one of the low stage-side compression mechanism (3) and the high stage-side compression mechanism (4) being a two-cylinder rotary type compression mechanism, and the other thereof being a scroll type compression mechanism, wherein

the rotary type compression mechanism has a rotor (34a, 34b)and a blade (38) reciprocating between a top dead center and a bottom dead center with the rotation of the rotor (34a, 34b) while the tip end thereof is in contact with the rotor (34a, 34b); and

a suction shutoff of the scroll type compression mechanism is accomplished when the rotor is at a position C of being rotated through -80 degrees from a position corresponding to the bottom dead center, at a position D of being rotated through -100 degrees from the position corresponding to the bottom dead center, or between the positions C and D, or at a position E of being rotated through 80 degrees from the position corresponding to the bottom dead center, at a position F of being rotated through 100 degrees from the position corresponding to the bottom dead center, or between the positions E and F.
The compressor according to claim 6, wherein
the low stage-side compression mechanism (3) is configured by the rotary type compression mechanism, and the high stage-side compression mechanism (4) is configured by the scroll type compression mechanism.
The compressor according to claim 7, wherein
the scroll type compression mechanism has a capacity control mechanism including an exhaust port (60) for refrigerant gas; and

the suction shutoff is accomplished when the exhaust port (60) is closed by an orbiting scroll (44) of the scroll type compression mechanism.