JP2005076902A - Compression unit for refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compression unit for a refrigerator that has an appreciable refrigerating capacity by preventing bypassing of working fluid via an oil separator, even during displacement control of a compressor by speed control of a motor. <P>SOLUTION: The oil separator 5 separates oil mixed in helium gas discharged from the compressor 1. The oil held in the oil separator 5 is returned to a low pressure part 16 of the compressor 1 via an oil return passage 25 to cool the motor 14. The oil in an oil sump in a casing 12 of the compressor 1 is pumped up by an oil pump 17 that supplies it to a compression element 13 to cool helium gas increased in temperature by compression in the compression element 13. According to a signal from an oil level sensor 29 for detecting an oil level in the oil separator 5, a valve travel control part 31 controls the travel of a flow control valve 27 in the oil return passage 25. The oil level in the oil separator 5 can be held at a given level to prevent bypassing of helium gas from the oil separator 5 to the compressor 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a compressor unit for a refrigerator.

  Conventionally, as a refrigerator using, for example, helium gas as a working fluid, there is one as shown in FIG. 3 (see Japanese Patent Laid-Open No. 9-32779: Patent Document 1). The compression unit included in the refrigerator separates the compressor 101 that compresses helium gas, the cooler 104 that cools the discharge gas of the compressor 101, and the oil discharged from the compressor 101 together with the helium gas. The oil separator 105 to be recovered is sequentially connected, and the working fluid from the oil separator 105 is supplied to the expander 108 via the adsorber 107. The compressor 101 of the compression unit is a hermetic compressor in which a compression element 113 and a motor 114 are accommodated in a casing 112. The oil accumulated in the casing 112 is pumped up by an oil pump 117 driven by the motor 114, cooled by the cooler 104, and injected into the compression element 113 of the compressor through the injection passage 138. The compressed gas that has been compressed and heated by the compression element 113 is cooled. Further, the oil recovered by the oil separator 105 is returned to the compressor casing 112 through the oil return passage 139 connected to the lower portion of the oil separator 105, and the motor 114 in the casing 112 is returned. Is cooling.

  The oil separator 105 connects an auxiliary oil return passage 196 at a predetermined position higher than a lower part to which the oil return passage 139 is connected, and excess oil is passed through the auxiliary oil return passage 196 to the oil return passage 196. Returning to 139, the oil level does not become higher than the predetermined position.

However, in the conventional compressor unit of the refrigerator, when the rotation speed of the motor 114 is controlled by an inverter to control the capacity of the compressor, the rotation speed of the motor 114 is set to a low rotation speed and a low capacity operation is performed. As a result, the amount of oil discharged from the compression element 113 together with the helium gas decreases. As a result, the oil level of the oil separator 105 falls below the connection position of the auxiliary oil return passage 196, and the helium gas returns into the casing 112 of the compressor via the auxiliary oil return passage 196. Bypass occurs. As a result, there is a problem that the supply amount of helium gas to the expander 108 is reduced and the refrigeration capacity of the refrigerator is reduced.
Japanese Patent Laid-Open No. 9-32779 (FIG. 2)

  Accordingly, an object of the present invention is to provide a refrigerator having a good refrigerating capacity that can prevent bypassing of the working fluid through the oil separator even when the capacity of the compressor is controlled by controlling the rotation speed of the motor. It is to provide a compression unit.

In order to achieve the above object, a compression unit of a refrigerator according to the present invention comprises a compression element that compresses a working fluid, a motor that drives the compression element, a casing that houses the compression element and the motor, and the motor. A compressor having an oil pump that is driven to feed oil accumulated in the casing to at least the compression element;
A rotational speed control unit for controlling the rotational speed of the motor of the compressor;
An oil separator that separates oil from the fluid discharged from the compressor and stores the separated oil inside;
An oil level sensor for detecting the height of the oil level in the oil separator;
An oil return passage for returning oil from the oil separator to the compressor;
A flow control valve provided in the oil return passage;
And a valve opening degree control unit that controls the opening degree of the flow rate control valve so that the oil level detected by the oil level sensor has a predetermined height.

  According to the said structure, the working fluid compressed with the said compression element is discharged from the said compressor with the oil supplied with the said oil pump. The oil discharged from the compressor together with the working fluid is separated by the oil separator. The separated oil is returned from the oil separator to the compressor through the oil return passage. When the rotation speed of the motor is controlled and changed by the rotation speed control unit, the capacity of the oil pump driven by the motor changes, so that the amount of oil discharged from the compressor changes. Therefore, since the amount of oil separated by the oil separator changes, the oil level in the oil separator changes. Here, the opening degree of the flow control valve is controlled by the valve opening degree control unit based on a signal from an oil level sensor that detects the height of the oil level in the oil separator. Thereby, the height of the oil surface in the oil separator is kept at a predetermined height. Therefore, the conventional auxiliary oil return passage is not required, and the disadvantage that the working fluid bypasses to the compressor through the auxiliary oil return passage is reliably prevented. Further, the height of the oil surface of the oil separator is, for example, not less than the height corresponding to the difference between the pressure in the oil separator and the pressure of the compressor part to which the oil return passage is connected. Thus, the disadvantage that the working fluid bypasses to the compressor via the oil return passage is reliably prevented.

  Further, even if the number of revolutions of the motor changes, the oil level of the oil separator is stably maintained at a predetermined height, so that the oil separator is installed within a range in which the capacity of the compressor is controlled. Therefore, the bypass of the working fluid and the oil leakage to the downstream side of the oil separator are effectively prevented. As a result, the refrigerator using this compression unit can exhibit a stable refrigeration capacity in the controlled operating range.

  Moreover, since the compression unit of the said refrigerator can delete the auxiliary oil return path connected to the conventional oil separator, the piping structure of oil can be simplified, As a result, the effort and cost of manufacture can be reduced.

  The compression unit of the refrigerator of one embodiment is characterized in that the oil return passage returns oil to the compression element of the compressor.

  According to the embodiment, the oil in the oil separator is returned to the compression element of the compressor via the oil return passage. Therefore, the working gas compressed by the compression element is efficiently cooled by the oil. Also, the compression element is efficiently lubricated. As a result, a refrigerator provided with this compression unit can obtain a stable refrigeration capacity.

In one embodiment of the compressor unit of the refrigerator, the compressor has a low-pressure portion formed in the casing and filled with fluid sucked by the compressor,
The oil return passage is characterized by returning oil to the low pressure portion of the compressor.

  According to the above embodiment, the oil level of the oil separator is not affected by the pressure difference between the oil separator and the low pressure portion of the compressor, even if the working fluid is easily bypassed through the oil return passage. Is adjusted by the valve opening degree control unit, so that the bypass of the working fluid is effectively prevented. Therefore, the refrigerator provided with this compression unit can obtain a stable refrigerating capacity.

  The compression unit of the refrigerator of one embodiment is characterized in that the oil return passage returns oil to the motor of the compressor.

  According to the embodiment, the oil in the oil separator is returned to the motor of the compressor via the oil return passage. Therefore, since the motor is effectively cooled, the refrigeration capacity of the refrigerator using the compression unit is stabilized, and the refrigeration efficiency is improved.

  Thus, the compression unit of the refrigerator of the present invention is driven by the compression element that compresses the working fluid, the motor that drives the compression element, the casing that houses the compression element and the motor, and the motor. A compressor having at least an oil pump for sending oil accumulated in the casing to the compression element, a rotation speed control unit for controlling the rotation speed of the motor of the compressor, and a fluid discharged from the compressor An oil separator that separates oil and stores the separated oil inside, an oil level sensor that detects the height of the oil level in the oil separator, and the oil separator that supplies oil to the compressor. The opening degree of the flow control valve is controlled so that the oil return passage, the flow control valve provided in the oil return passage, and the oil level detected by the oil level sensor have a predetermined height. And the valve opening degree control unit. Even when the rotation speed is controlled and the capacity of the compressor is controlled, the oil level of the oil separator can be maintained at a predetermined height, so that the bypass of the working fluid through the oil return flow path and the oil Inconveniences such as oil leakage to the downstream side of the separator can be effectively prevented. In addition, since the auxiliary oil return passage connected to the conventional oil separator can be eliminated, the oil piping configuration can be simplified, and as a result, manufacturing effort and cost can be reduced.

  In the compressor unit of the refrigerator according to one embodiment, the oil return passage returns oil to the compression element of the compressor, so that the working gas compressed by the compression element can be efficiently cooled by the oil, and The compression element can be efficiently lubricated. As a result, a refrigerator provided with this compression unit can obtain a stable refrigeration capacity.

  In the compressor unit of the refrigerator according to one embodiment, the compressor has a low-pressure portion filled with fluid sucked by the compressor formed in the casing, and the oil return passage is formed in the low-pressure portion of the compressor. Since the oil is returned, even if the working fluid bypass is likely to occur due to the pressure difference between the oil separator and the low pressure part, the height of the oil level of the oil separator is adjusted by the valve opening control part. The bypass of the working fluid can be effectively prevented. Therefore, the refrigerator provided with this compression unit can obtain a stable refrigerating capacity.

  In the compressor unit of the refrigerator according to an embodiment, the oil return passage returns oil to the motor of the compressor, so that the motor can be effectively cooled. Therefore, the refrigerating capacity of the refrigerator using the compressor unit is improved. It can be stabilized and the refrigeration efficiency can be improved.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

  FIG. 1 is a diagram showing a refrigerator using a compression unit according to the first embodiment of the present invention. The refrigerator includes a compression unit having a compressor 1, a cooler 4, and an oil separator 5, and helium gas as a working fluid compressed by the compressor 1 is expanded by a cryogenic expander 8 so as to be cryogenic. Is what you get.

  The compressor 1 is a sealed type in which a casing 12 contains a scroll-type compression element 13, a variable speed motor 14 that drives the compression element 13, and an oil pump 17 that is driven by the motor 14. This is a compressor.

  The motor 14 is connected to an inverter power supply 15 as a rotation speed control unit, and the motor 14 is driven by controlling the rotation frequency of the motor 14 by controlling the output frequency of the inverter power supply 15. The capacity of the compressor 1 is controlled.

  The oil pump 17 is a positive displacement pump such as a trochoid pump, and pumps up oil from an oil reservoir formed in a lower portion of the casing 12 and supplies the oil to the compression element 13 through an oil passage 19. The helium gas heated to a high temperature by the compression element 13 is cooled by the oil supplied through the oil passage 19.

  The oil passage 19 is provided with a filter 21 and a throttle mechanism 22 including an orifice, and the downstream side of the throttle mechanism 22 passes through the cooler 4.

  The compressor 1 temporarily stores the high-pressure helium gas compressed by the compression element 13 in the high-pressure part 18 formed in the upper part of the casing 12, and through a discharge line 23 communicating with the high-pressure part 18, It discharges to the outside of the compressor 1. Further, a low pressure portion 16 filled with the low pressure helium gas from the expander 8 is formed in the casing 12 of the compressor 1. The compression element 13, the motor 14, and the oil pump 17 are disposed in the low pressure portion 16.

  The discharge line 23 is provided with a cooler 4 for cooling the helium gas discharged from the compressor 1 and an oil separator 5 for separating the oil mixed in the helium gas.

  The oil separator 5 is an oil separator provided in the casing, and separates the oil mixed in the helium gas from the compressor 1 and accumulates the oil in the casing. One end of an oil return passage 25 for returning the accumulated oil to the compressor 1 is connected to the lower part of the casing. The other end of the oil return passage 25 is connected to the low pressure portion 16 in the casing 12 of the compressor 1. The oil return passage 25 is provided with a filter 26 and a flow rate adjusting valve 27. The motor 14 located in the low-pressure part 16 is cooled by the oil supplied to the compressor 1 from the oil separator 5 through the oil return passage 25. Note that the oil returned to the low pressure portion 16 in the oil return passage 25 may be applied to a portion other than the motor 14 to cool or lubricate this portion.

  The casing of the oil separator 5 is provided with an oil level sensor 29 that detects the surface of the oil accumulated inside by ultrasonic waves and detects the height of the oil level from the bottom of the casing.

  The flow rate adjustment valve 27 includes a valve body that is electromagnetically driven, and the opening degree is adjusted by a valve opening degree control unit 31 connected to the oil level sensor 29. That is, the valve opening degree control unit 31 adjusts the valve opening degree of the flow rate adjusting valve 27 so that the oil level of the oil separator detected by the oil level sensor 29 becomes a predetermined height. It is like that.

  An adsorber 7 is provided downstream of the oil separator 5 in the discharge line 23 to capture oil that has not been separated by the oil separator 5. The cryogenic expander 8 is connected downstream of the adsorber 7, and the helium gas that has been expanded by the cryogenic expander 8 to a low pressure is sucked into the compressor 1 via the suction line 24. .

  When the cold heat to be generated by the cryogenic expander 8 is relatively small and the amount of helium gas to be supplied to the expander 8 is relatively small, The output frequency of the compressor 1 is reduced, the rotational speed of the motor 14 of the compressor 1 is reduced, and the capacity of the compressor 1 is reduced. Then, as the rotational speed of the motor 14 decreases, the discharge amount of the oil pump 17 decreases and the flow rate of oil supplied to the compression element 13 decreases. As a result, the amount of oil mixed in the helium gas discharged from the compressor 1 is reduced, so that the amount of oil separated by the oil separator 5 is reduced and the oil level of the oil separator 5 is increased. Decrease. This decrease in the oil level is detected by the oil level sensor 29, and based on a signal from the oil level sensor 29, the opening degree of the flow rate adjusting valve 27 is reduced by the valve opening degree control unit 31. As a result, the flow rate of oil in the oil return passage 25 decreases, and the flow rate of oil supplied from the oil separator 5 to the low pressure portion of the compressor 1 decreases. As a result, the oil level of the oil separator 5 is maintained at a predetermined height. Thus, since the flow rate of the oil return passage 25 is controlled based on the height of the oil surface of the oil separator 5, the oil separator 5 does not require a conventional auxiliary oil return passage. . Therefore, when the compressor operates at a low capacity, the oil level of the oil separator is lower than the connection part of the auxiliary oil return passage, and it is ensured that the inconvenience that helium gas bypasses the compressor from this connection part. Can be prevented.

  The height of the oil level of the oil separator 5 controlled by the valve opening degree control unit 31 is a height corresponding to the difference between the pressure in the oil separator 5 and the pressure in the low pressure part 16 of the compressor. That's it. This ensures that helium gas bypasses the compressor 1 via the oil return passage 25 even when the difference between the pressure in the oil separator 5 and the pressure in the low pressure portion 16 is relatively large. Can be prevented.

  In this way, the compressor unit of the refrigerator of this embodiment can effectively prevent the bypass of helium gas from the oil separator 5 to the compressor 1 even when the compressor 1 is operated at a low capacity. . Therefore, the refrigeration capacity of the refrigerator can be stabilized and the refrigeration efficiency can be improved.

  On the other hand, in the compressor unit of the refrigerator, when the cold heat to be generated by the cryogenic expander 8 is relatively large and the amount of helium gas to be supplied to the expander 8 is relatively large, the inverter power supply 15 The output frequency of the compressor 1 is increased, the number of revolutions of the motor 14 of the compressor 1 is increased, and the capacity of the compressor 1 is increased. Then, as the rotation speed of the motor 14 increases, the discharge amount of the oil pump 17 increases. The oil passage 19 through which the oil from the oil pump 17 flows is made to have a flow rate of a predetermined amount or less by the throttle mechanism 22, but for example, due to a change in viscosity due to a rise in oil temperature, the oil passage 19 May increase in flow rate. As a result, the flow rate of oil supplied to the compression element 13 increases, and the amount of oil mixed in the helium gas discharged from the compressor 1 may increase. In this case, the amount of oil separated by the oil separator 5 increases, and the oil level of the oil separator 5 increases. Then, an increase in the oil level is detected by the oil level sensor 29, and the opening degree of the flow rate adjusting valve 27 is increased by the valve opening degree control unit 31 based on a signal from the oil level sensor 29. The As a result, the flow rate of the oil in the oil return passage 25 increases, and as a result, the oil level of the oil separator 5 is maintained at a predetermined height. Therefore, the problem that the oil level of the oil separator 5 rises abnormally and the oil is sent to the expander 8 is reliably prevented. As described above, the compression unit of the present embodiment reliably holds the oil level of the oil separator 5 at a predetermined height even when the compressor 1 is operated at a high capacity, and the refrigerating capacity of the refrigerator. Can be maintained well.

  Further, since the oil separator 5 can eliminate the auxiliary oil return passage as in the prior art, the oil piping configuration can be simplified, and as a result, manufacturing effort and cost can be reduced.

  Drawing 2 is a figure showing a refrigerator provided with a compression unit of other embodiments.

  The compressor unit of the refrigerator of the present embodiment is that the oil separated from the helium gas by the oil separator 5 is directly supplied to the compressor element 13 of the compressor via the oil return passage 51. Different from the compression unit. Further, the point that the oil pumped up by the oil pump 7 from the oil reservoir located in the lower part in the casing 12 of the compressor is supplied to the motor 14 in the casing 12 through the oil passage 52 is that of the refrigerator of FIG. Different from the compression unit. 2, the same components as those in the compressor unit of the refrigerator shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 2, the compression unit of the refrigerator of the present embodiment connects one end of the oil return passage 51 to the lower part of the casing of the oil separator 5, and the other end of the oil return passage 51 is connected to the lower portion of the casing. It is connected to the compression element 13 of the compressor 1. The oil return passage 51 is provided with a filter 26 and a flow rate adjusting valve 27. The valve opening degree of the flow rate adjusting valve 27 is controlled by the valve opening degree control unit 31 based on the oil level of the oil separator 5 as in the case of the compressor unit of the refrigerator shown in FIG.

  Further, one end of an oil passage 52 is connected to the oil pump 7 provided in the compressor 1, and the other end of the oil passage 52 is connected to the low pressure portion 16 of the compressor. The oil passage 52 is provided with a filter 21 and a throttle mechanism 22. The oil pumped up from the oil reservoir cools the motor 14 located in the low pressure portion 16. The oil supplied from the oil passage 52 to the low pressure part 16 may be applied to other parts other than the motor 14 to cool or lubricate this part.

  One end of the auxiliary passage 53 is connected to the oil passage 52, and the other end of the auxiliary passage 53 is connected to the oil return passage 51. Oil is supplied to the oil return passage 51 in an auxiliary manner from the oil reservoir of the compressor via the auxiliary passage 53. The auxiliary passage 53 is provided with a filter 54 and a throttle mechanism 55 so that the flow rate of the auxiliary passage 53 becomes a predetermined amount or less by the throttle mechanism 55.

  In the compressor unit of the refrigerator of the present embodiment, when controlling the output frequency from the inverter power supply 15 and changing the rotational speed of the motor 14 of the compressor 1 to control the capacity of the compressor 1, Depending on the operating conditions, the amount of oil discharged with the helium gas from the compressor increases or decreases. As a result, the oil level of the oil separator 5 tends to rise or fall. Here, the opening degree of the flow rate adjusting valve 27 of the oil return passage 51 connected to the oil separator 5 is controlled by the valve opening degree control unit 31 based on the height of the oil level of the oil separator 5. The Therefore, regardless of the amount of oil discharged from the compressor 1, the oil level of the oil separator 5 is stably maintained. Therefore, the disadvantage that the oil level of the oil separator as in the prior art is abnormally lowered and the helium gas is bypassed to the compressor via the auxiliary oil return passage is effectively prevented. Further, the problem that the oil level of the oil separator rises abnormally and oil leaks from the oil separator to the expander is prevented.

  The flow rate of the oil return passage 51 that supplies oil to the compression element 13 of the compressor is adjusted according to the height of the oil surface of the oil separator 5 that correlates with the amount of oil discharged from the compression element 13. Is done. Accordingly, both the amount of oil supplied to the compression element 13 and the oil level of the oil separator 5 are adjusted appropriately. As a result, the amount of oil discharged from the compression element 13 and the amount of oil accumulated in the oil separator can be appropriately set within the capacity range in which the compressor 1 is controlled. As a result, the refrigerator The refrigeration capacity can be stabilized over the operation range in which is controlled.

  In the above embodiment, the compression element 13, the motor 14, and the oil pump 17 are arranged in the low pressure portion 16 in the casing 12 of the compressor 1. However, the compression element 13 is compressed in the casing 12 of the compressor. Alternatively, a high-pressure portion filled with high-pressure helium gas may be formed, and the compression element 13 compression element motor 14 and the oil pump 17 may be disposed in the high-pressure portion.

  Further, although helium gas is used as the working fluid of the refrigerator, other fluids other than helium gas may be used.

  Moreover, although the said compression unit connected to the cryogenic expander 8 and comprised the refrigerator, it may connect with the other apparatus which receives supply of a working fluid, and may comprise a refrigerator. The adsorber 7 may be deleted.

  The oil level sensor is not limited to one using ultrasonic waves, and may be another sensor such as one using electromagnetic waves.

It is a figure which shows the refrigerator using the compression unit of 1st Embodiment of this invention. It is a figure which shows a refrigerator provided with the compression unit of other embodiment. It is a figure which shows the refrigerator provided with the conventional compression unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 4 Cooler 5 Oil separator 7 Adsorber 8 Cryogenic expander 12 Casing 13 Compression element 14 Motor 16 Low pressure part 17 Oil pump 19 Oil passage 21 Filter 22 Throttle mechanism 23 Discharge line 24 Suction line 25 Oil return passage 26 Filter 27 Flow control valve 29 Oil level sensor 31 Valve opening control unit

Claims (4)

A compression element (13) that compresses the working fluid, a motor (14) that drives the compression element (13), a casing (12) that houses the compression element (13) and the motor (14), and the motor A compressor (1) having an oil pump (17) driven by (14) and sending at least oil accumulated in the casing (12) to the compression element (13);
A rotational speed control unit (15) for controlling the rotational speed of the motor (14) of the compressor;
An oil separator (5) for separating oil from the fluid discharged from the compressor (1) and storing the separated oil inside;
An oil level sensor (29) for detecting the height of the oil level in the oil separator (5);
An oil return passage (25, 51) for returning oil from the oil separator (5) to the compressor (1);
A flow control valve (27) provided in the oil return passage (25, 51);
A valve opening degree control unit (31) for controlling the opening degree of the flow rate control valve (27) so that the oil level detected by the oil level sensor (29) becomes a predetermined height. A compressor unit for a refrigerator. In the compression unit of the refrigerator according to claim 1,
The compressor unit of the refrigerator, wherein the oil return passage (51) returns oil to the compression element (13) of the compressor. In the compression unit of the refrigerator according to claim 1,
In the compressor (1), a low pressure part (16) filled with the fluid sucked by the compressor (1) is formed in the casing (12),
The compressor unit of the refrigerator, wherein the oil return passage (25) returns oil to the low pressure part (16) of the compressor. In the compression unit of the refrigerator according to claim 1,
The compressor unit of the refrigerator, wherein the oil return passage (25) returns oil to the motor (14) of the compressor.

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