JP2008101559A - Scroll compressor and refrigeration cycle using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely inject refrigerant into a compression chamber to improve performance of a compressor in a gas injection cycle. <P>SOLUTION: A scroll compressor 40 comprises: a fixed scroll 7 in which a spiral lap 7b is stood on a head plate 7a; a swirl scroll 8 opposed to the fixed scroll and rotatably disposed; and a back pressure chamber disposed to a back surface of the swirl scroll, and intermediate in pressure between discharge pressure and suction pressure. In the swirl scroll, a spiral lap 8b is stood on the head plate 8a. A plurality of compression chambers 13 are formed between the lap of the fixed scroll and the lap of the swirl scroll. A pipe 1 for injecting gaseous refrigerant in the back pressure chamber, is provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a scroll compressor, and more particularly to a scroll compressor suitable for a refrigeration cycle.

  Patent Document 1 describes the use of a gas injection cycle in order to improve the performance of the refrigeration cycle. As described in this publication, in a refrigeration cycle using a gas injection cycle, two decompression devices are disposed in the decompression unit, and a gas-liquid separator is disposed between the two decompression devices. Then, a gas refrigerant having an intermediate pressure (injection pressure) that does not contribute to the heat absorption capability generated in the evaporation process is taken out from the gas-liquid separator, and the taken out gas refrigerant is injected (injected) into the compression chamber of the compressor. Since the refrigerant guided to the compressor is compressed from the intermediate pressure, the work of the compressor is reduced. As a result, the performance of the refrigeration cycle can be improved, and the pressure loss in the evaporator is reduced because the injection gas does not pass through the evaporator.

  There are various methods for gas injection. In the scroll compressor described in Patent Document 1, one injection port is provided in the fixed scroll to inject the refrigerant. Furthermore, the position of the injection port is determined so that the gas refrigerant can be sequentially and intermittently supplied to two compression chambers having different sealed volumes, and the supply time thereof is relatively long. At that time, the injection port position is determined so that the injected gas refrigerant does not flow out to the suction side, and if there is only one injection port, the gas refrigerant can be reliably injected into the compression chamber.

  Another example of refrigerant injection is described in Patent Document 2. In the scroll compressor described in this publication, liquid refrigerant is injected into the back pressure chamber instead of gas injection. Since the low-temperature liquid refrigerant is guided from the back pressure chamber to the compression chamber, an increase in the discharge temperature is suppressed, and as a result, an increase in the temperature of the motor windings, lubricating oil, and the like can be suppressed. Here, since the injection into the back pressure chamber is performed without directly injecting into the compression chamber, the force for pressing the orbiting scroll against the fixed scroll is ensured even when the ratio of the suction pressure and the discharge pressure is large.

JP 2003-120555 A JP-A-5-26188

  In the scroll compressor, the pressure in the compression chamber varies with the orbiting motion of the orbiting scroll. In the scroll compressor described in Patent Document 1, since there is one injection port, the injection amount may be extremely reduced due to pressure fluctuations in the compression chamber depending on the phase (position) of the orbiting scroll. In the worst case where the injection amount is reduced, the refrigerant flows backward from the compression chamber to the injection port.

  In a refrigeration cycle having an injection cycle, the refrigerant may be operated without being injected into the compressor depending on the operating conditions. In this case, the injection port provided in the fixed scroll becomes a dead volume that does not contribute to compression. And when the part becomes a low pressure according to the turning of the orbiting scroll, the re-expansion loss increases and the compressor efficiency decreases.

  Further, when the gas refrigerant is injected into the compression chamber, the pressure in the compression chamber increases, and the axial force for separating the orbiting scroll and the fixed scroll from each other increases. As a result, a gap is generated between the tooth tip and the tooth bottom of both the turning and fixed scroll wraps, the sealing performance of the compression chamber is deteriorated, and the efficiency of the compressor is reduced.

  In the scroll compressor described in the above-mentioned patent document 2, by injecting liquid refrigerant into the back pressure chamber, an increase in discharge temperature can be suppressed and an increase in the pulling force between the orbiting scroll and the fixed scroll can be suppressed. However, in gas injection, it was possible to reduce the amount of work of the compressor by separating a gas refrigerant that does not contribute to the heat absorption capability, but such an effect cannot be expected in liquid injection.

  Also in liquid injection, if the pressure in the compression chamber fluctuates, the injection amount may be extremely reduced, or the refrigerant may flow backward from the compression chamber to the injection pipe through the back pressure chamber. The scroll compressor described in Patent Document 2 employs differential pressure lubrication, and therefore, when injected into the back pressure chamber, the amount of lubrication to a sliding portion such as a bearing decreases. In the differential pressure lubrication, since there is no pump for lubrication as described below, it is difficult to increase the amount of lubrication.

  Here, in the differential pressure lubrication, the lubricating oil stored in the bottom of the hermetic container of the hermetic compressor is used to slide the bearings and the like using the differential pressure between the discharge pressure and the back pressure chamber pressure (back pressure). Supply to the department. When the back pressure is reduced, the lubricating oil in the atmosphere of the discharge pressure flows into the back pressure chamber through the sliding portion such as a bearing, and the back pressure is maintained. In this differential pressure lubrication, when injected into the back pressure chamber, the amount of lubricating oil flowing into the back pressure chamber decreases, and the amount of lubrication to the sliding portion such as the bearing decreases.

  The present invention has been made in view of the above-mentioned problems of the prior art, and is to reliably inject a refrigerant into a compression chamber and to prevent backflow of the injection refrigerant. Another object of the present invention is to reliably inject refrigerant and improve the performance of the compressor. Still another object of the present invention is to suppress a reduction in the performance of the compressor when the refrigerant is not injected. The present invention aims to achieve at least one of these objects.

  In order to achieve the above object, a feature of the present invention is that a scroll compressor having a back pressure chamber for pressing the orbiting scroll against the fixed scroll is formed on the back side of the orbiting scroll. An injection pipe for injecting a gaseous refrigerant having a pressure intermediate between the discharge pressure and the suction pressure is provided.

  And in this feature, liquid refrigerant having substantially the same pressure may be mixed in the gaseous refrigerant to be injected, and it has a shaft that drives the orbiting scroll, and this shaft has a through-hole formed in its axial center. A lubricating oil pump may be provided at the lower end of the shaft, and the sliding portion of the scroll compressor may be forcibly lubricated.

  Another feature of the present invention that achieves the above object is that the fixed scroll having a spiral wrap standing on the end plate, the orbiting scroll that is pivotably provided facing the fixed scroll, and the back of the orbiting scroll are provided. It has a back pressure chamber that is an intermediate pressure between the discharge pressure and the suction pressure, and in the orbiting scroll, a spiral wrap is erected on the end plate, and there are a plurality of spaces between the fixed scroll wrap and the orbiting scroll wrap. In the scroll compressor forming the compression chamber, a circuit for injecting a gaseous refrigerant is provided in the back pressure chamber.

  In this feature, the injection circuit may inject a liquid refrigerant in addition to the gaseous refrigerant, and has an airtight container that accommodates the orbiting scroll and the fixed scroll, and is provided at the center of the rear surface of the orbiting scroll. Means for forming a first space having a pressure close to the discharge pressure, providing means for guiding the lubricating oil stored in the bottom of the sealed container to the first space, and leaking the lubricating oil from the first space to the back pressure chamber In addition, a means for returning most of the lubricating oil in the first space to the bottom of the sealed container without mixing with the compressed gas in the sealed container may be provided.

  Further, in the above feature, a communication path is formed at the tooth tip of the outermost peripheral wrap of the fixed scroll, and the back pressure chamber is adjusted according to the difference between the suction pressure or the compression chamber pressure introduced through the communication path and the pressure of the back pressure chamber. A back pressure adjusting valve that allows the fluid in the pressure chamber to escape to the suction chamber or the compression chamber via the communication path may be provided to adjust the pressure in the back pressure chamber, and the back pressure chamber and the compression chamber, or the back pressure chamber, A back pressure hole communicating with the suction chamber may be formed in the end plate of the orbiting scroll to adjust the pressure of the back pressure chamber, and the back pressure chamber and the compression chamber or the back pressure chamber and the suction chamber are intermittently connected. A communicating back pressure hole may be formed on the end plate of the orbiting scroll to adjust the pressure in the back pressure chamber.

  Still another feature of the present invention that achieves the above object is that a compressor, a switching valve, a first heat exchanger, a first pressure reducing valve, a gas-liquid separator, a second pressure reducing valve, and a second heat exchanger are sequentially connected by piping. In the refrigeration cycle, the compressor has a back pressure chamber for pressing the orbiting scroll against the fixed scroll on the back side of the orbiting scroll, and the discharge pressure and suction pressure of the scroll compressor are formed in the back pressure chamber. An injection pipe for injecting a gaseous refrigerant at an intermediate pressure is provided, and the gas-liquid separator and the injection pipe of the compressor are connected.

  According to the present invention, the gas refrigerant or the liquid-gas mixed refrigerant is reliably injected into the compressor even when the pressure in the compression chamber fluctuates, so that the performance of the refrigeration cycle is improved. In addition, since the injection refrigerant does not flow backward from the compression chamber, a check valve in the injection pipe becomes unnecessary. Furthermore, it is possible to suppress a reduction in the efficiency of the compressor when the refrigerant is not injected.

  Hereinafter, an embodiment of a refrigeration cycle according to the present invention and a scroll compressor used therefor will be described with reference to the drawings. FIG. 1 shows a system diagram of a refrigeration cycle 50 having an injection cycle. FIG. 1 shows a refrigeration cycle 50 of an air conditioner. The air conditioner switches between a cooling operation cycle and a heating operation cycle by a switching valve 41. Hereinafter, the refrigeration cycle 50 will be described for the cooling operation. In the cooling operation, the switching valve 41 is switched as shown by a solid line in FIG. 1, and the refrigerant flows in the direction of the arrow.

  The refrigeration cycle 50 includes a scroll compressor 40 that compresses refrigerant, a switching valve 41 that switches the flow direction of the discharge gas of the scroll compressor 40, a first heat exchanger 42 that functions as a condenser, and the first heat. The first and second expansion valves 43 and 45 for reducing the pressure of the refrigerant condensed in the exchanger 42, the gas-liquid separator 44 disposed between the first and second expansion valves 43 and 45, and the second expansion valve 45 And a second heat exchanger 46 for evaporating the decompressed refrigerant, and these devices are connected by piping in order.

An injection pipe 47 is connected to the gas-liquid separator 44. One end of the injection pipe 47 is connected to the scroll compressor 40. In the injection pipe 47, the gas refrigerant separated by the gas-liquid separator 44 from the gas-liquid mixed refrigerant compressed by the compressor 40 and condensed by the first heat exchanger 42 circulates. A check valve 48 is provided in the middle of the injection pipe 47. The compressor 40, the first heat exchanger 42, the first pressure reducing valve 43, the gas-liquid separator 44, the injection pipe 47, and the like form an injection cycle.
The 1st heat exchanger 42 is arrange | positioned at the outdoor side, outdoor air is ventilated by the outdoor fan which is not shown in figure, and heat-exchanges with outdoor air forcibly. The first expansion valve 43 and the second expansion valve 45 are expanded by reducing the refrigerant pressure in two stages in any of the cooling and heating cycles. The first expansion valve 43 and the second expansion valve 45 have variable valve openings and are controlled by a control device (not shown).

The gas-liquid separator 44 provided between the first expansion valve 43 and the second expansion valve 45 separates the liquid refrigerant and the gas refrigerant contained in the refrigerant expanded by the first expansion valve 43 or the second expansion valve 45. To do. Then, the liquid refrigerant is sent out to the second expansion valve 45 and the gas refrigerant is sent out to the injection pipe 47. Since the refrigerant in the gas-liquid separator 44 is expanded by the first expansion valve 43 and depressurized, it is an intermediate pressure between the discharge pressure and the suction pressure of the compressor 40. The second heat exchanger 46 is a heat exchanger disposed on the indoor side, and is forcibly exchanged with room air by an indoor fan (not shown).

The operation of the refrigeration cycle 50 configured in this manner and shown in the present embodiment will be described in detail below. The high-temperature and high-pressure gas refrigerant compressed by the scroll compressor 40 is sent to the first heat exchanger 42 through the switching valve 41 and exchanges heat with the outdoor air sent from the outdoor fan by the first heat exchanger 42. To dissipate heat and condense. The condensed refrigerant is sent to the first expansion valve 43, and is reduced to an intermediate pressure that is lower than the discharge pressure of the scroll compressor 40 and higher than the suction pressure of the scroll compressor 40. Then, it becomes a gas-liquid two-phase wet refrigerant and is sent to the gas-liquid separator 44. The wet refrigerant is separated into a liquid refrigerant and a gas refrigerant by the gas-liquid separator 44.
The gas refrigerant separated by the gas-liquid separator 44 passes through the injection pipe 47 and the check valve 48 and is injected into the back pressure chamber of the scroll compressor 40 described later. In the scroll compressor 40, it flows into the compression chamber from the back pressure chamber. Therefore, in the cooling operation cycle, since the gas refrigerant separated by the gas-liquid separator 44 is compressed from the intermediate pressure by the compressor 40, the work amount of the scroll compressor 40 is reduced, and the efficiency of the refrigeration cycle can be improved. .

  The reason is that even if the gas refrigerant is expanded to a low pressure and led to the second heat exchanger 46, it does not contribute to the heat absorption capability generated in the evaporation process of the second heat exchanger 46 acting as an evaporator. This is because, in this embodiment, since the latent heat absorption when the liquid refrigerant evaporates and changes into a gas refrigerant is used, only the liquid refrigerant is necessary for the evaporator, and no gas refrigerant is necessary. Accordingly, the refrigerant is not expanded to a low pressure such as the suction pressure of the compressor 40, but is expanded to an intermediate pressure, and the gasified portion in that state is led to the compression chamber in the middle of compression. Since the intermediate-pressure gas refrigerant is compressed by the compressor 40, power for compressing the gas refrigerant from a low pressure such as a suction pressure to an intermediate pressure is saved. Furthermore, since the separated gas refrigerant does not pass through the second heat exchanger 46, the pressure loss in the second heat exchanger 46 can be reduced.

  On the other hand, the liquid refrigerant separated by the gas-liquid separator 44 is sent to the second expansion valve 45 and further depressurized to become a low-temperature low-pressure gas-liquid two-phase wet refrigerant. The wet refrigerant exchanges heat with the indoor air blown by the indoor fan in the second heat exchanger 46 to absorb heat and vaporize. As a result, it becomes a gas refrigerant and flows into the suction side of the scroll compressor 40. The gas refrigerant sent from the second heat exchanger 46 is mixed with the gas refrigerant injected into the compression chamber in the middle of compression formed in the scroll compressor 40 and compressed. Then, it is compressed to a predetermined pressure by the scroll compressor 40 and sent to the first heat exchanger 42 as a high-temperature and high-pressure refrigerant gas.

  The above is the action of each device during the cooling operation cycle. During the heating operation cycle, the switching valve 41 is switched as shown by the broken line in FIG. 1, and the refrigerant flows in the direction opposite to the arrow in the figure. . In this case, the first heat exchanger 42 functions as an evaporator, and the second heat exchanger 46 functions as a condenser. The refrigerant depressurized by the second pressure reducing valve 45 flows into the gas-liquid separator 44.

Details of the scroll compressor 40 used in this injection cycle will be described with reference to FIGS. FIG. 2 is a longitudinal sectional view of an embodiment of the scroll compressor according to the present invention. The fixed scroll 7 is in a cylindrical shape so as to surround a wrap 7b, a mirror plate 7a formed in a disc shape, a wrap 7b erected in a spiral shape on the mirror plate 7a, and an outer peripheral side of the mirror plate 7a. And a formed support portion 7d. The surface of the end plate 7a on which the wrap 7b is erected forms a tooth bottom 7c. The support portion 7d is formed on the outer peripheral portion of the fixed scroll 7, and the support portion 7d is fixed to the frame 17 with a bolt or the like. The peripheral edge portion of the frame 17 fixed by the support portion 7d and integrated with the fixed scroll 7 is fixed to the case 9 by welding or the like.

  The orbiting scroll 8 disposed to face the fixed scroll 7 is held in the frame 17 so as to be orbitable. The orbiting scroll 8 has a disc-shaped end plate 8a, a spiral wrap 8b provided upright on the end plate 8a, and a boss 8d provided at the center of the rear surface of the end plate 8a. Similar to the fixed scroll 7, the surface of the end plate 8a on which the wrap 8b is formed forms a tooth bottom 8c. A portion of the orbiting scroll 8 that is on the outer diameter side of the portion where the wrap 8 b is formed and that is in contact with the tooth end side end surface of the fixed scroll 7 forms an end plate surface 8 e of the orbiting scroll 8.

  The case 9 is a hermetically sealed container, and houses a scroll portion having the fixed scroll 7 and the orbiting scroll 8 in the upper portion, and a motor 16 that drives the orbiting scroll 8 in the lower portion. Lubricating oil 39 is stored at the bottom of the case 9. A rotor 16 a of the motor 16 is attached to the shaft 10 that drives the orbiting scroll 8. The shaft 10 is rotatably provided on the frame 17 and is coaxial with the axis of the fixed scroll 7. A crank 10a is provided at the tip of the shaft 10, and a boss portion 8d of the orbiting scroll 8 is rotatably attached to the crank 10a via an orbiting bearing 11.

The axis of the orbiting scroll 8 is eccentric from the axis of the fixed scroll 7 by a predetermined distance δ. The wrap 8b of the orbiting scroll 8 is overlapped with the wrap 7b of the fixed scroll 7 while being changed by a predetermined angle in the circumferential direction. An Oldham ring 12 is attached to the back side of the orbiting scroll 8 so that the orbiting scroll 8 does not rotate with respect to the fixed scroll 7 but relatively moves.

  When the wrap 8b of the orbiting scroll 8 and the wrap 7b of the fixed scroll 7 are combined and the orbiting scroll 8 is orbited, a plurality of compression chambers 13 are formed between the two wraps 7b and 8b. The compression chamber 13 has a crescent shape, and the volume continuously decreases as the compression chamber 13 moves to the center. In the case of a so-called asymmetric wrap, a plurality of compression chambers 13 are formed on the inner wall surface side and the outer wall surface side of the wrap 8b of the orbiting scroll 8, as shown in FIG. It is the turning outer line side compression chamber 13b.

  A suction portion 38 is formed at the outer diameter side end portion of the wrap 7 b of the fixed scroll 7. A suction port 14 that is a blind hole is formed from the opposite side of the fixed scroll 7 from the surface on which the wrap 7b is formed. The suction port 14 guides the refrigerant from the second heat exchanger 46 to the scroll unit during the cooling operation cycle. The suction portion 38 is formed with a blind hole from the lap surface so that the groove depth gradually changes to a position corresponding to the suction port 14 and communicates with a part of the suction port 14 at its end. The suction part 38 moderates a change in the flow direction of the refrigerant sucked from the suction port 14.

A space formed by the wrap 7 b of the fixed scroll 7 and the wrap 8 b of the orbiting scroll 8 opened to the suction portion 38 is referred to as a suction chamber 20. The suction chamber 20 is a space in the middle of sucking the refrigerant from the second heat exchanger 46 during the cooling operation cycle and from the first heat exchanger 42 during the heating operation cycle. When the phase of the orbiting motion of the orbiting scroll 8 advances, the suction port 14 side is closed by the two scroll wraps 7b and 8b, and the compression chamber 13 is changed. In the vicinity of the spiral center of the end plate 7a of the fixed scroll 7, a discharge port 15 is formed as a through hole. The discharge port 15 communicates with the innermost compression chamber 13.

  The operation of the scroll compressor of this embodiment configured as described above will be described below. When the motor 16 rotationally drives the shaft 10, the rotation is transmitted to the orbiting scroll 8 via the orbiting bearing 11 held by the crank 10 a portion of the shaft 10. Thereby, the orbiting scroll 8 orbits around the axis of the fixed scroll 7 with the orbiting radius of the distance δ. At this time, the protrusion formed on the Oldham ring 12 is moved in the groove formed on the back side of the orbiting scroll 8 so that the orbiting scroll 8 does not rotate.

  As the orbiting scroll 8 orbits, the compression chamber 13 formed between the fixed and orbiting wraps 7b and 8b continuously moves to the center. At the same time, the volume of the compression chamber 13 is continuously reduced. Due to the movement of the orbiting scroll 8, the refrigerant sucked from the suction port 14 is sequentially compressed in each compression chamber 13. The compressed refrigerant is discharged from the discharge port 15. The refrigerant discharged from the discharge port 15 passes through the outer peripheral portion of the fixed scroll 7 in the case 9, and then passes from the discharge pipe 6 attached to the side portion of the case 9 to the lower portion of the scroll portion to the outside of the compressor 40. It is sent to the switching valve 41.

  A positive displacement or centrifugal oil supply pump 21 is attached to the lower end of the shaft 10. When the shaft 10 rotates, the oil pump 21 also rotates, and the lubricating oil 39 stored in the bottom of the case 9 is sucked from the lubricating oil suction port 25 provided in the oil pump case 22. The lubricating oil 39 sucked by the oil pump 21 is guided from the discharge port 29 of the oil pump through the through hole 3 formed in the shaft portion of the shaft 10 to the respective portions of the scroll compressor 40 through the axially extending through hole 3.

  Part of the lubricating oil 39 guided to the upper part is in the first space 33 formed by the frame 17 and the shaft 10, the orbiting scroll 8, and the collar-like orbiting boss member 34 provided on the boss portion 8 d of the orbiting scroll 8. Inflow. A horizontal hole 24 extending in the radial direction is formed in the lower part of the shaft 10, and a part of the lubricating oil 39 is ejected from the horizontal hole 24 to lubricate the auxiliary bearing 23 that rotatably supports the lower part of the shaft 10. Return to the reservoir of the lubricating oil 39 at the bottom of the case 9.

  A lateral hole 4 extending in the radial direction is formed in the upper part of the shaft 10 and facing the main bearing 5, and a part of the lubricating oil 39 is ejected from the lateral hole 4 to lubricate the main bearing 5. The lubricating oil 39 that has lubricated the main bearing 5 flows into the first space 33. The lubricating oil 39 that reaches the upper part of the crank 10 a of the shaft 10 through the vertically extending through hole 3 lubricates the swivel bearing 11 and then flows into the first space 33. Here, oil supply grooves 27 and 28 having a sufficiently wider groove width than the bearing gaps of the bearings 5 and 11 are formed in the shaft 10. Since the oil supply grooves 27 and 28 are wide, the flow resistance when the lubricating oil 39 passes through the main bearing 5 and the slewing bearing 11 is small, and a pressure gradient is almost generated between the upper and lower ends of the bearings 5 and 11. Absent. Therefore, the refrigerant dissolved in the lubricating oil 39 can be prevented from foaming under reduced pressure, and high bearing reliability can be obtained.

  Most of the lubricating oil flowing into the first space 33 falls to the bottom of the case 9 through the oil drain hole 26a and the oil drain pipe 26b formed in the frame 17. At this time, since the outlet of the oil drain pipe 26b is brought close to the inner wall surface of the case 9 and the outlet position is formed so that the lubricating oil 39 flows downward, the lubricating oil 39 is mixed with the discharge gas and taken out of the machine. It is suppressed. As a result, it is possible to prevent the lubricating oil 39 in the compression chamber 13 from being extremely reduced and impairing the reliability of the compressor 40.

  Among the remaining lubricating oil 39 flowing into the first space 33, the minimum lubricating oil necessary for lubricating the Oldham ring 12 and the compression chamber 13 and sealing the compression chamber 13 is located above the main bearing 5. It flows into the back pressure chamber 18 from an oil leakage means provided between the upper end surface of the seal member 32 located at the end and the end surface of the swivel boss member 34. Here, the back pressure chamber 18 is a space formed between the back side of the orbiting scroll 8 and the frame 17.

  By the way, in the scroll compressor 40, the fixed scroll 7 and the orbiting scroll 8 are arranged to face each other, and when the orbiting scroll 8 orbits, the volumes of the plurality of compression chambers 13 formed between the orbiting and fixed wraps 7b and 8b. Decreases sequentially. Due to the compression action in the scroll compressor 40, an axial force (hereinafter referred to as a pulling force) is generated in the fixed scroll 7 and the orbiting scroll 8. When the fixed and orbiting scrolls 7 and 8 are pulled apart, the tooth tip of the wrap 7b and the tooth bottom of the orbiting scroll 8 of the fixed scroll 7 and the tooth tip of the wrap 8b and the tooth bottom of the fixed scroll 7 of the orbiting scroll 8 are separated. A gap is generated between them, the sealing property of the compression chamber 13 is deteriorated, and the efficiency of the compressor is lowered.

  Therefore, a back pressure chamber 18 serving as a pressure (intermediate pressure) between the discharge pressure and the suction pressure of the compressor 40 is formed on the back side of the end plate 8a of the orbiting scroll 8. When the intermediate pressure is applied as the back pressure of the orbiting scroll 8, the orbiting scroll 8 is pressed toward the fixed scroll 7 to cancel the pulling force. At the same time, an attractive force is generated between the orbiting scroll 8 and the fixed scroll 7.

  However, if the attractive force is too large, the thrust force acting between the orbiting scroll 8 and the fixed scroll 7 increases, and the sliding friction between the tooth tips and the tooth bottoms of both wraps 7b, 8b increases. Therefore, the attractive force is adjusted to an appropriate magnitude. In order to adjust the attractive force, that is, the back pressure, a back pressure hole 35 is formed in the end plate 8a of the orbiting scroll 8 as shown in FIG.

  The back pressure hole 35 is a communication passage that communicates the back pressure chamber 18 and the compression chamber 13. When the back pressure increases, the fluid in the back pressure chamber 18 automatically escapes to the compression chamber 13 according to the pressure difference between the back pressure chamber 18 and the compression chamber 13, and the back pressure is maintained at an appropriate value. On the other hand, when the back pressure becomes low, the fluid in the compression chamber 13 flows into the back pressure chamber 18 to increase the back pressure and maintain the back pressure at an appropriate value.

  The seal member 32 has a ring shape and is inserted into an annular groove 31 formed in the frame 17 together with a wave spring (not shown). The seal member 32 partitions the first space 33 that is the discharge pressure of the compressor 40 and the back pressure chamber 18 that is an intermediate pressure between the suction pressure and the discharge pressure of the compressor 40. As the oil leakage means, a plurality of holes 30 are formed in the turning boss member 34 so as to extend in the axial direction. When the orbiting scroll 8 orbits, the plurality of holes 30 move on the circumference with the seal member 32 interposed therebetween, and the openings thereof alternately face the first space 33 and the back pressure chamber 18. As a result, the lubricating oil 39 in the first space 33 is transferred to the back pressure chamber 18.

  The amount of oil supplied to the back pressure chamber 18 can be freely adjusted by changing the number of the plurality of holes 30 formed in the turning boss member 34 and the diameter and depth of each hole 30. When the back pressure increases, the lubricating oil 39 flowing into the back pressure chamber 18 flows into the compression chamber 13 through the back pressure hole 35 formed in the end plate 8 a of the orbiting scroll 8. Then, when the orbiting scroll 8 is turned, the revolving scroll 8 moves to the center of the orbiting scroll 8 and is discharged from the discharge port 15. Part of the lubricating oil 39 discharged from the discharge port 15 flows out of the machine from the discharge pipe 6. The remaining lubricating oil 39 is separated from the refrigerant and stored in the bottom of the case 9.

  The position of the back pressure hole 35 described above is set as follows. A back pressure hole 35 is formed in the end plate 8 a of the orbiting scroll 8. At that time, the back pressure hole 35 is positioned so that the pressure at the back pressure hole 35 portion of the compression chamber 13 formed with the turning of the orbiting scroll 8 becomes a value close to a predetermined back pressure value. FIG. 3 shows an example of the back pressure hole 35. The pressure in the back pressure hole 35 of the compression chamber 13 is the pressure in the swirling outer line side compression chamber 13b.

  Since the pressure in the orbiting outer line side compression chamber 13 b varies while the orbiting scroll 8 makes one revolution, the average pressure during one revolution becomes the pressure in the back pressure hole 35 of the compression chamber 13. FIG. 4 shows the relationship between the turning angle of the orbiting scroll 8 and the pressure in the compression chamber 13. The horizontal axis is the crank angle corresponding to the turning angle of the orbiting scroll 8. As the orbiting scroll 8 orbits, the pressure in the orbiting outer line side compression chamber 13b increases from the suction pressure to the discharge pressure as indicated by the line ABC in the figure. On the other hand, the pressure in the swivel extension side compression chamber 13a rises as indicated by a line A-D-E-C in the figure.

  At this time, since the position of the compression chamber 13 moves to the center along with the turning of the orbiting scroll 8, the back pressure hole 35 may not be included in the compression chamber 13. Therefore, only when the compression chamber 13 includes the back pressure hole 35, that is, only in the opening section, the pressure of the line FG, which is the pressure of the turning outer line side compression chamber 13 b, acts on the back pressure hole 35. The back pressure hole 35 is formed so that the average pressure of the line FG is balanced with the back pressure acting on the back pressure chamber 18.

  Since the pressure on the compression chamber 13 side of the back pressure hole 35 fluctuates as indicated by the line FG as described above, the refrigerant flows in a certain crank angle range during the turning of the orbiting scroll 8. The pressure chamber 18 changes from the compression chamber 13 to the compression chamber 13 and from a compression chamber 13 to the back pressure chamber 18 in a certain crank angle range. The flow of the refrigerant that reciprocates through the back pressure hole 35 causes a so-called respiratory loss. Therefore, in order to reduce this breathing loss, the back pressure hole 35 is intermittently connected to the back pressure chamber 18 and the compression chamber 13.

  An example in which the back pressure hole 35 is intermittently communicated with the back pressure chamber and the compression chamber will be described with reference to FIGS. 5 and 6. FIG. 5 is an enlarged longitudinal sectional view showing a portion around the back pressure hole 35 in the scroll compressor 40 shown in FIG. FIG. 6 is a cross-sectional view of the end plate 8a, which is the tooth bottom surface of the orbiting scroll 8, and shows only the fixed scroll 7 and the orbiting scroll 8. FIG. A back pressure hole 35 having a U-shaped cross-section is formed in the end plate 8a of the orbiting scroll 8 and a communication groove 36 formed on the surface of the fixed scroll 7 on the side of the wrap 7b and extending obliquely outward from the radial direction to the inner diameter side. Show.

  The communication groove 36 constitutes a part of the back pressure chamber 18. When the orbiting scroll 8 makes one revolution, the opening 35a on the back pressure chamber 18 side of the back pressure hole 35 follows a locus indicated by a circle 37 in FIG. At this time, the back pressure chamber 18 and the compression chamber 13 communicate with each other only during a crank angle range during one revolution, specifically, while the opening 35 a of the back pressure hole 35 faces the communication groove 36. In the other range of the crank angle, the opening 35a of the back pressure hole 35 is closed by the surface 7e of the fixed scroll 7 on the lap 7b side, and the back pressure chamber 18 and the compression chamber 13 are shut off. Since the back pressure chamber 18 and the compression chamber 13 are intermittently communicated, the length of the line FG in the compression curve shown in FIG. 4 is shortened, and the pressure fluctuation can be suppressed.

  Next, the structure as the compressor 40 used for an injection cycle is demonstrated using FIG. An injection pipe 1 is provided through the case 9 so as to communicate with the back pressure chamber 18. The end of the injection pipe 1 is connected to the injection pipe 47 shown in FIG.

  In the scroll compressor 40 configured as described above, the gas refrigerant separated by the gas-liquid separator 44 is injected into the back pressure chamber 18. The injected gas refrigerant flows into the compression chamber 13 through the back pressure hole 35 together with the lubricating oil that has traveled through the shaft 10 from the lubricating oil reservoir at the bottom of the case 9 and reached the back pressure chamber 18. To do. As described above, since the back pressure hole 35 is intermittently communicated with the back pressure chamber 18 and the compression chamber 13, the pressure fluctuation on the compression chamber 13 side from which the gas refrigerant flows out from the back pressure chamber 18 is reduced. , Breathing loss is also reduced. As a result, it is possible to reduce respiratory loss and increase the amount of injection as compared with the case where the gas refrigerant is directly injected into the compression chamber 13.

  When the injection amount of the gas refrigerant increases, the power for compressing the gas refrigerant that does not contribute to the heat absorption capability in the evaporator from a low pressure to an intermediate pressure can be greatly reduced. Conventionally, it has been difficult to inject all of the separated gas refrigerant due to pressure loss due to respiratory loss and flow path resistance, and some of the gas refrigerant has been compressed via an evaporator. In this embodiment, since the injection amount is increased, such useless compression can be avoided.

  Since the gas refrigerant separated by the gas-liquid separator 44 does not pass through the second heat exchanger 46, the pressure loss in the second heat exchanger 46 can be reduced. Further, since the influence of the pressure fluctuation on the compression chamber 13 side where the gas refrigerant flows out is suppressed to be small, the injection pressure can be set to a pressure higher than the maximum pressure at which the gas refrigerant flows out. As a result, it is possible to prevent the gas refrigerant from flowing back from the compression chamber 13 through the back pressure chamber 18 to the injection pipe 47, and the check valve 48 serving as a noise source during the injection cycle is unnecessary.

  In the conventional method of directly injecting the refrigerant gas into the compression chamber 13, the pressure in the compression chamber 13 is increased by the injection of the refrigerant gas, so that the revolving scroll 8 is separated from the fixed scroll 7 as compared with the case where the injection is not performed. There was a risk that the force would increase and the efficiency of the compressor would decrease.

  On the other hand, according to the present embodiment, the gas refrigerant is caused to flow into the back pressure chamber 18 and the pressure of the gas refrigerant is slightly reduced due to the pressure loss when passing through the back pressure hole 35. Flow into. As a result, the pulling force increases and the pressing force also increases, so that it is possible to prevent a reduction in efficiency of the compressor 40 due to the separation of the fixed and turning scrolls 7 and 8.

  In the conventional method of directly injecting into the compression chamber 13, the space on the compression chamber 13 side formed by the injection port and the check valve becomes a dead volume that does not contribute to compression when operated without injection, and is re-expanded. There was a risk of loss. According to the present embodiment, since no injection port is required, a dead volume does not occur, and the efficiency of the compressor 40 does not decrease even if the operation is performed without injection. Further, according to the present embodiment, the lubricating oil 39 is supplied to the main bearing 5 and the slewing bearing 11 by the oil supply pump. Therefore, even if the refrigerant gas is injected into the back pressure chamber 18, the amount of oil supplied to the bearing sliding portion does not decrease.

  In the above embodiment, the gas refrigerant separated by the gas-liquid separator 44 is injected into the back pressure chamber 18, but some liquid refrigerant may be injected into the back pressure chamber 18 in addition to the gas refrigerant. When liquid refrigerant is also injected, low-temperature liquid refrigerant flows into the compression chamber 13 via the back pressure chamber 18, so that the compression chamber 13 is cooled and the discharge temperature of the refrigerant gas discharged from the discharge port 15 is increased. Can be lowered. As a result, temperature rises of the motor windings and lubricating oil can be suppressed.

  Another embodiment of the scroll compressor 40 according to the present invention will be described with reference to FIGS. FIG. 7 is a vertical cross-sectional view of the scroll compressor 40, and FIG. 8 is an enlarged vertical cross-sectional view showing a back pressure adjusting valve 2 part included in the scroll compressor 40. This embodiment differs from the embodiment shown in FIG. 2 in that the oil supply to the bearing portion is a differential pressure oil supply performed by the pressure difference between the discharge pressure and the back pressure, and the back pressure hole is replaced by a back pressure hole. The back pressure is adjusted by using the pressure regulating valve 2.

  The differential pressure oil supply structure will be described. The lubricating oil 39 is stored in a lubricating oil reservoir 39a at the bottom of the case 9, and the atmospheric pressure in the lubricating oil reservoir 39a is a discharge pressure. On the other hand, the pressure in the back pressure chamber 18 is lower than the discharge pressure. Therefore, the lubricating oil 39 stored in the lubricating oil reservoir 39a has a through hole 3 formed in the axial center portion of the shaft 10 due to the pressure difference between the atmospheric pressure in the lubricating oil reservoir 39a and the pressure in the back pressure chamber 18. And flows into the back pressure chamber 18.

At this time, a part of the lubricating oil 39 opens to a portion of the shaft 10 facing the main bearing 5 and lubricates the main bearing 5 through the lateral hole 4 extending in the radial direction in the shaft 10. After the main bearing 5 is lubricated, the back pressure chamber 18 is reached. The remaining lubricating oil 39 reaches the upper part of the crank 10 a of the shaft 10 through the through hole 3, lubricates the swivel bearing 11 and flows into the back pressure chamber 18. When passing through the main bearing 5 and the slewing bearing 11, the lubricating oil 39 is throttled because the bearing gap is small, and flows into the back pressure chamber 18 at a pressure lower than the discharge pressure.

  When the back pressure of the lubricating oil 39 flowing into the back pressure chamber 18 increases, the back pressure adjusting valve 2 provided in the communication passage to the suction chamber 20 or the compression chamber 13 opens. Since the back pressure regulating valve 2 is opened, the lubricating oil 39 flows from the back pressure chamber 18 into the suction chamber 20 or the compression chamber 13 and is discharged from the discharge port 15 through the compression chamber 13.

Next, the configuration and operation of the back pressure adjusting valve 2 will be described. A stepped hole extending in the axial direction is formed from the back side so that the valve body 2a of the back pressure regulating valve 2 can be accommodated outside the wrap 7b of the fixed scroll 7. On the other hand, a hole is formed from the back pressure chamber 18 side at a position corresponding to the stepped hole. The hole on the back pressure chamber 18 side forms a lower space 2 d communicating with the back pressure chamber 18.

A hole that communicates the stepped hole and the back pressure chamber 18 side is formed obliquely on the side of the stepped hole. The back pressure chamber 18 side end portion of the obliquely formed hole is connected to a communication path 2 f that is a groove formed on the surface of the fixed scroll 7 on the lap 7 b side. The space 2e formed by the stepped hole and the oblique hole communicates with the suction chamber 20 or the compression chamber 13 through the communication path 2f. A valve body 2a is arranged on the upper surface of the lower space 2d so that the space can be closed. The valve body 2a is pressed to the lower space 2d side by a spring 2b fixed to the lower part of the member 2c fitted into the stepped hole.

Therefore, the valve body 2a has a force generated by the pressure of the lower space 2d communicating with the back pressure chamber 18 and the force generated by the pressure of the suction chamber 20 or the compression chamber 13 transmitted to the space 2e via the communication passage 2f, and the spring. When it becomes higher than the total pressing force of 2b, it moves upward. Then, the lower space 2d and the space 2e are communicated. That is, the back pressure adjusting valve 2 releases the fluid in the back pressure chamber 18 to the suction chamber 20 or the compression chamber 13 when the pressure in the back pressure chamber 18 becomes higher than a preset value.

Also in the structure having the back pressure adjusting two valves, the gas refrigerant injected into the back pressure chamber 18 through the injection pipe 47 is combined with the lubricating oil that has reached the back pressure chamber 18. Then, it flows into the suction chamber 20 or the compression chamber 13 through the back pressure regulating valve 2. Therefore, also in the present embodiment, the back pressure regulating valve 2 intermittently connects the back pressure chamber 18 and the suction chamber 20 or the compression chamber 13, so that the pressure in the back pressure chamber 18 is the suction chamber 20 or the compression chamber 13. The pressure is almost constant without being influenced by the pressure fluctuation on the side, and good injection with little respiratory loss can be realized.

  Further, according to the present embodiment, it is possible to reduce the breathing loss and increase the injection amount as compared with the case where the gas refrigerant is directly injected into the compression chamber 13, and prevent the gas refrigerant from flowing back into the injection pipe 47. The check valve 48 is unnecessary, and the gas refrigerant flows into the back pressure chamber 18 and then passes through the back pressure regulating valve 2, and there is a pressure loss at that time, so that the embodiment shown in FIG. For the same reason, the pressing force increases as well as the separation force between the fixed and orbiting scrolls 7 and 8, which prevents the volumetric efficiency from being lowered, so there is no need for a conventional injection port, so there is no dead volume and no injection. There is an effect that the efficiency of the compressor does not decrease during operation.

  In this embodiment, since the lubricating oil 39 is supplied to the main bearing 5 and the slewing bearing 11 by the differential pressure between the discharge pressure and the back pressure, the amount of gas refrigerant flowing into the back pressure chamber 18 due to the injection is large. Accordingly, the amount of lubricating oil flowing into the back pressure chamber 18 via the bearing is reduced accordingly. That is, when injection is not performed, the flow of fluid flowing out from the back pressure chamber can be regarded as the flow of lubricating oil from the oil reservoir at the bottom of the case, but when injected, the flow of injection gas is added to the flow of lubricating oil. As a result, when the flow rate of the fluid from the back pressure chamber 18 is constant, the amount of lubricating oil decreases.

  Therefore, the pressing force of the spring 2b of the back pressure adjustment valve 2 is reduced. When the pressing force of the spring 2b is small, the amount of fluid that escapes from the back pressure chamber 18 to the suction chamber 20 or the compression chamber 13 increases. The injection pressure is adjusted so that the amount of lubricating oil flowing into the back pressure chamber 18 is approximately the same as when the back pressure chamber 18 is not injected. Thereby, reduction of the amount of oil supply to a bearing part can be avoided. Similar to the embodiment shown in FIG. 2, not only the gas refrigerant but also a gas refrigerant containing a liquid refrigerant may be injected.

1 is a system diagram of a refrigeration cycle according to the present invention. It is a longitudinal section of one example of a scroll compressor concerning the present invention. It is a top view of the compression chamber formed by the turning scroll and fixed scroll which the scroll compressor shown in FIG. 2 has. It is a graph explaining the change of the pressure in the compression chamber of the scroll compressor shown in FIG. It is a detailed longitudinal cross-sectional view of the back pressure hole formed in the scroll compressor shown in FIG. It is a top view of the back pressure hole formed in the scroll compressor shown in FIG. It is a longitudinal cross-sectional view of the other Example of the scroll compressor based on this invention. It is a longitudinal cross-sectional view of the back pressure regulating valve which the scroll compressor shown in FIG. 2 or FIG. 7 has.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection pipe 2 Back pressure adjustment valve 7 Fixed scroll 8 Orbiting scroll 13 Compression chamber 18 Back pressure chamber 35 Back pressure hole 40 Scroll compressor 50 Refrigeration cycle

Claims (11)

  In the scroll compressor in which a back pressure chamber for pressing the orbiting scroll against the fixed scroll is formed on the back side of the orbiting scroll, the gas pressure of the intermediate pressure between the discharge pressure and the suction pressure of the scroll compressor is formed in the back pressure chamber. A scroll compressor comprising an injection pipe for injecting a refrigerant.   The scroll compressor according to claim 1, wherein a liquid refrigerant having substantially the same pressure is mixed in the gaseous refrigerant to be injected.   The shaft has a shaft for driving the orbiting scroll, and the shaft has a through hole formed in an axial center portion thereof, and a lubricating oil pump is provided at the lower end of the shaft to forcibly lubricate the sliding portion of the scroll compressor. The scroll compressor according to claim 1.   A fixed scroll in which a spiral wrap is erected on the end plate, a revolving scroll that is opposed to the fixed scroll and is turnable, and a back that is an intermediate pressure between the discharge pressure and the suction pressure on the back of the revolving scroll. A scroll compressor in which a spiral wrap is erected on an end plate in the orbiting scroll, and a plurality of compression chambers are formed between the fixed scroll wrap and the orbiting scroll wrap. A scroll compressor comprising a circuit for injecting a gaseous refrigerant in a back pressure chamber.   The scroll compressor according to claim 4, wherein the injection circuit injects a liquid refrigerant in addition to the gaseous refrigerant.   A sealed container that accommodates the orbiting scroll and the fixed scroll has a first space that is close to the discharge pressure at the center of the back surface of the orbiting scroll, and the lubricating oil stored in the bottom of the sealed container is the first. Means for guiding the oil into the space, and means for leaking the lubricating oil from the first space to the back pressure chamber, and mixing most of the lubricating oil in the first space with the compressed gas in the sealed container. 5. The scroll compressor according to claim 4, further comprising means for returning to the bottom of the closed container.   The scroll compressor according to claim 6, wherein the injection circuit injects a liquid refrigerant in addition to a gaseous refrigerant.   A communication passage is formed at the tooth tip of the outermost peripheral wrap of the fixed scroll, and the fluid in the back pressure chamber is determined according to the difference between the suction pressure introduced through the communication passage or the pressure of the compression chamber and the pressure of the back pressure chamber. 5. The scroll compressor according to claim 4, wherein a back pressure adjusting valve is provided to release the air to the suction chamber or the compression chamber through the communication path, and the pressure of the back pressure chamber is adjusted.   5. A back pressure hole for communicating the back pressure chamber and the compression chamber or the back pressure chamber and the suction chamber is formed in the end plate of the orbiting scroll to adjust the pressure of the back pressure chamber. Scroll compressor described in 1.   The pressure of the back pressure chamber is adjusted by forming a back pressure hole in the end plate of the orbiting scroll for intermittently communicating the back pressure chamber and the compression chamber or the back pressure chamber and the suction chamber. 4. The scroll compressor according to 4.   In a refrigeration cycle in which a compressor, a switching valve, a first heat exchanger, a first pressure reducing valve, a gas-liquid separator, a second pressure reducing valve, and a second heat exchanger are sequentially connected by piping, the compressor is defined in claim 1. A refrigerating cycle, wherein the gas-liquid separator is connected to an injection pipe of the compressor.

Images