JP5903595B2 - Ultra-low temperature refrigeration equipment - Google Patents

Description

  The present invention relates to an ultra-low temperature refrigeration apparatus including an oil separator having a simple configuration that can reliably return the oil to the compressor when the oil level separated from the refrigerant gas exceeds the required level. The present invention relates to a technique for obtaining good lubrication of a scroll compressor.

  The scroll compressor accommodates an electric element of an electric motor configuration and a scroll compression element driven by the electric element in a hermetic container, and the scroll compression element is a fixed scroll in which a spiral wrap is erected on the surface of the end plate And an orbiting scroll that is disposed to face the fixed scroll and has a spiral wrap standing on the surface of the end plate, and orbits as the rotating shaft of the electric element rotates.

  Further, in this scroll compressor, the wrap of the fixed scroll and the wrap of the orbiting scroll are eccentric from each other, and a compression space confined by meshing by mutual contact is formed on this eccentric direction line. The compression space is gradually reduced from the outside to the inside by the orbiting motion of the orbiting scroll accompanying the rotation of the rotating shaft of the electric element, thereby forming a low pressure chamber, an intermediate pressure chamber, and a high pressure chamber. The refrigerant gas sucked into the refrigerant gas suction port from the suction pipe communicating with the outer peripheral portion of the refrigerant to the low pressure chamber is compressed in the low pressure chamber, the intermediate pressure chamber, and the high pressure chamber in order, and communicated with the high pressure chamber. It is the structure which discharges from the discharge port formed in the part.

  In this way, the refrigerant compressed by the scroll compressor and discharged from the discharge port is condensed by the condenser, the liquid refrigerant decompressed and expanded by the expansion valve is evaporated by the evaporator, and the refrigerant circulation returns to the scroll compressor again. In the refrigeration system that configures the circuit, the internal low-pressure scroll compressor is employed, and the scroll compression is achieved by injecting a part of the liquid refrigerant that has exited the condenser from the compression space of the scroll compression element into the intermediate pressure chamber. Some control the discharge gas temperature of the machine (see Patent Document 1).

  As described above, when the refrigerant is compressed by the scroll compressor, a part of the lubricating oil in the scroll compressor is discharged in a state of being mixed in the gas refrigerant and enters the refrigerant circulation circuit constituting the refrigeration apparatus. In particular, the refrigerant evaporation temperature in an evaporator into which refrigerant decompressed and expanded by an expansion valve is introduced by a refrigeration apparatus including a scroll compressor is a temperature range of −40 ° C. or lower, which is an ultra-low temperature range, for example, −40 ° C. to −60. When an ultra-low temperature refrigeration apparatus of about 0 ° C. is configured, the refrigerant circulation amount in the refrigerant circuit constituting the refrigeration apparatus decreases due to the throttling effect of the expansion valve. For this reason, the amount of refrigerant gas sucked into the entrance of the compression space of the scroll compression element is reduced, and the amount of lubricating oil contained in the refrigerant gas is also reduced along with this. This results in poor lubrication of the scroll compression element.

  In addition, as described above, when the amount of oil in the refrigerant gas decreases and the supply of lubricating oil to the scroll compression element is insufficient, the fixed scroll wrap and the swing scroll wrap forming the compression space are provided. The amount of oil required to seal the meshing part due to sliding contact with each other is insufficient, and it becomes difficult to form an oil film necessary for this part of the seal. Cause a decline.

  When a liquid injection circuit for supplying a part of the liquid refrigerant to the intermediate pressure portion of the scroll compression element is provided as in Patent Document 1 in order to suppress the temperature rise of the scroll compression element portion, the liquid to be liquid injected The refrigerant also causes the oil in the intermediate pressure chamber in the compression space to flow, and there is a concern that the oil lubrication of this scroll compression element will be insufficient.

  As described above, when an refrigeration apparatus having an ultra-low temperature of about −40 ° C. to −60 ° C. is configured, a decrease in the amount of oil sucked with a decrease in the amount of refrigerant gas sucked into the entrance of the compression space of the scroll compression element; Insufficient oil lubrication of the scroll compression element is a concern due to the lack of oil in the intermediate pressure chamber caused by the liquid refrigerant to be liquid injected.

  By the way, in the case where a liquid injection circuit for supplying a part of the liquid refrigerant to the intermediate pressure portion of the scroll compression element and supplying the liquid refrigerant is provided, as described above, the liquid refrigerant to be liquid-injected causes the intermediate pressure chamber of the compression space to There is a risk that a lot of oil will be washed away. For this reason, a refrigeration apparatus provided with an oil separator in place of the liquid injection circuit has also been proposed (see, for example, Patent Document 2).

JP 2011-047383 A JP 2011-33209 A

  According to such a refrigeration apparatus, when a large amount of oil is mixed in the refrigerant gas discharged from the scroll compressor, the oil can be effectively recovered. Thereby, it may be possible to compensate for a decrease in the amount of oil suction accompanying a decrease in the amount of refrigerant gas sucked into the entrance of the compression space of the scroll compression element.

  However, as described above, in the case of configuring an ultra-low temperature refrigeration apparatus, it is preferable to provide a liquid injection circuit, and in the case of a configuration in which this is not provided, there is a concern about an increase in the temperature of the scroll compression element section. The However, on the other hand, there is an urgent need for development of a means for fundamentally solving the problem caused by the installation of this circuit, that is, the oil shortage due to the oil flow from the intermediate pressure chamber caused by the liquid refrigerant to be liquid injected. .

  In view of these points, the present invention employs an internal low-pressure scroll compressor to form an ultra-low temperature refrigeration apparatus. When there is a liquid injection circuit that supplies to the intermediate pressure part of the compressor and an oil separator that recovers the mixed oil in the refrigerant gas discharged from the scroll compressor, friction occurs in the scroll part due to insufficient lubrication of the scroll compression element An object of the present invention is to provide an ultra-low temperature refrigeration apparatus including a scroll compressor suitable for use in ultra-low temperature refrigeration.

The ultra-low temperature refrigeration apparatus according to claim 1 of the present invention includes:
An electric element and a scroll compression element driven by the electric element are accommodated in a hermetic container, a lower space of the scroll compression element in the hermetic container is a low pressure chamber, and the upper part of the scroll compression element in the hermetic container The space is used as a discharge pressure space for refrigerant gas compressed by the scroll compression element, and the discharge pressure space is discharged from the discharge port while compressing the refrigerant gas sucked from the suction pipe communicating with the scroll compression element by the scroll compression element. A scroll compressor that discharges the refrigerant gas discharged to the outside of the sealed container,
The discharged refrigerant gas passes through a condenser and a receiver tank that stores liquid refrigerant, and after evaporating liquid refrigerant decompressed and expanded by an expansion valve using an evaporator, returns to the scroll compression element from the suction pipe again. Forming a circulation circuit,
An oil separator is installed on the refrigerant circuit in which the refrigerant gas discharged from the scroll compression element of the compressor is sent to the condenser outside the sealed container,
An oil return circuit for returning oil stored in the oil separator into the sealed container;
A part of the liquid refrigerant accumulated in the receiver tank or a part of the liquid refrigerant obtained by supercooling the refrigerant exiting the receiver tank with a supercooler is supplied to the compression chamber of the low pressure part or the intermediate pressure part of the scroll compression element. An oil injection circuit for supplying the oil separated from the refrigerant by the oil separator to the compression chamber of the low pressure part or the intermediate pressure part of the scroll compression element,
A low pressure sensor for detecting the internal pressure of the low pressure chamber is provided, and the control unit calculates the correlation between the pressure of the refrigerant and the enthalpy based on the output signal from the low pressure chamber, and calculates the correlation of the low pressure chamber. When the internal temperature is lower than the predetermined value, the solenoid valve provided in the oil injection circuit is opened, and the oil is compressed until the internal temperature of the low pressure chamber reaches the predetermined temperature. In an ultra-low temperature refrigeration system that cools to an ultra-low temperature of −40 ° C. or less supplied to a room,
The oil separator is
The refrigerant gas discharged from the scroll compression element is installed on a refrigerant circuit that is sent out of the sealed container,
A container that is long in the vertical direction,
Oil separating means installed on the upper side in the container;
A refrigerant delivery pipe for delivering the refrigerant gas separated by the oil separation means to the outside of the container;
A float that rises and falls according to the amount of oil separated and dropped by the oil separating means and stored in the bottom of the container;
A float valve that operates when the float rises above a predetermined level set in advance;
When the liquid level of the oil stored in the bottom of the container exceeds a predetermined level, the float valve is opened, and the oil stored in the bottom of the container is sucked and sent to the outside of the container. An oil return pipe for returning oil,
Further, the tip of the oil injection circuit is connected to the lowermost part in the container.

  According to the cryogenic refrigeration apparatus according to claim 1 of the present invention, in addition to the oil return circuit having the oil separator, the oil separated from the refrigerant by the oil separator is used as the compression chamber of the low pressure part or the intermediate pressure part of the scroll compression element. An oil injection circuit is provided for supplying the oil to the compression chamber of the low-pressure part or the intermediate-pressure part of the scroll compression element via the oil injection circuit. Therefore, even if a large amount of oil in the intermediate pressure chamber of the compression space is caused to flow by the liquid refrigerant that is liquid-injected, the oil is supplied simultaneously from the oil injection circuit. There is an advantage that generation can be suppressed.

According to the cryogenic refrigeration apparatus according to claim 1 of the present invention, the float and the float type valve are provided in the oil separator, and when the amount of oil stored in the oil separator exceeds a predetermined value, the oil return pipe is Since the oil can be automatically collected in the sealed container, there is an advantage that the oil supply automation can be realized simply and at low cost.

It is explanatory drawing which shows the refrigerant circuit used for the ultra-low temperature freezing apparatus which concerns on embodiment of this invention. It is sectional drawing which shows the ultra-low temperature compressor used for the refrigerant circuit. (A) is sectional drawing which shows the oil separator etc. which are used for the refrigerant circuit, (B) is the top view. (A) to (C) is an explanatory view showing the operation of the refrigerant circuit provided in the scroll compressor of the present embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a refrigerant circuit 1 constituting a refrigerant circuit used in the ultra-low temperature refrigeration apparatus according to the present embodiment. The refrigerant circuit 1 includes a strainer 2 for removing foreign matters such as sludge, and a liquid refrigerant. (Liquid refrigerant, the same shall apply hereinafter) for storing and gasifying, and a scroll-type ultra-low temperature compressor (hereinafter referred to as “low temperature / low pressure” gas refrigerant (a gaseous refrigerant, the same shall apply hereinafter)). Oil called lubricating oil contained in the high-temperature and high-pressure refrigerant discharged from the compressor 100 and separated and stored, and returned to the compressor 100 via an oil return circuit 23 described later. A separator 5, a heat exchanger 6 that acts as a condenser, a receiver tank 7 that stores liquid refrigerant that has flowed out of the heat exchanger 6, and a supercooler 8 that is installed integrally with the heat exchanger 6. A filter dryer 9 for removing moisture contained in the refrigerant, and a moisture indicator 10 for moisture detection, but are sequentially pipe connection.

  The refrigerant circuit 1 further includes a liquid injection circuit 21, an oil injection circuit 22, an oil return circuit 23, and a control unit 24, which will be described in detail later. In FIG. 1, reference numeral 25 denotes a low pressure sensor, and 26 denotes a high pressure sensor.

  The refrigerant circuit 1 on the outdoor side is connected to a pressure reducing device 13 such as an expansion valve and a heat exchanger 14 acting as an evaporator via an inter-unit piping 11 and 12 in an annular shape. It constitutes the refrigeration cycle. In FIG. 1, reference numeral 15 denotes a cooling fan that blows air to the heat exchanger 6 and the subcooler 8.

  Although the details of the compressor 100 will be described later, the compressor 100 is composed of a scroll-type ultra-low temperature compressor. As shown in FIG. 2, the fixed scroll 114 of the scroll compression element 102 provided in the upper part of the hermetic container 101 has a liquid. The end of the injection circuit 21 is connected. In addition, the cover 127 that is discharged by deflecting the flow of the refrigerant gas discharged upward from the discharge hole 113 that is a discharge port of the compressor 100 to the side of the cover 127 is in the vicinity of an outlet (not shown) that is opened in the upper wall. In addition, a temperature detector 60 is accommodated at the tip of the pipe P that penetrates the upper wall.

  The oil separator 5 separates oil mixed in the refrigerant gas discharged from the scroll compression element from the refrigerant gas. Further, particularly in the oil separator 5 of the present invention, as shown in FIG. 3, when the amount of oil separated and stored in the bottom of the container 5A of the oil separator 5 exceeds a predetermined level set in advance. In order to detect the liquid level of the oil mechanically and automatically and return it to the bottom side inside the closed container 141 of the compressor 100, a float type oil separator is used.

  As shown in FIG. 3, the float type oil separator 5 of the present embodiment includes an oil separating means 51 installed on the upper side in the container 5A, and refrigerant gas separated by the oil separating means 51 from the upper part of the container 5A. An outflow pipe 1B constituting a refrigerant delivery pipe that sends out to the outside, a float 52 that rises and falls according to the level of oil separated and dropped by the oil separation means 51 and stored in the bottom of the container 5A, and the float 52 are preset. A float type valve 53 that opens when it rises above the predetermined level, an oil pipe 54 that is connected to the float type valve 53 and is pulled out from the upper part of the container 5A, and a tip part of the oil pipe 54 And an oil return circuit 23 that constitutes an oil return pipe for oil return to which the base end portion is connected.

  The oil separating means 51 is composed of a filter formed in a substantially cylindrical shape by a perforated plate or the like. An upper portion of the filter is provided with an inflow pipe 1A (which constitutes a part of the refrigerant circuit 1) penetrating the filter lid and the container 5A, and the end portion of the inflow pipe 1A communicates with the inside of the filter. ing. Furthermore, the base end part of the outflow pipe 1B is attached to the upper part of the filter in a state of penetrating the container 5A, and the outflow pipe 1B and the inside of the filter communicate with each other.

  In the oil separation means 51, when the high-temperature and high-pressure refrigerant gas compressed and discharged by the compressor 100 flows into the filter from the upper part through the inflow pipe 1A, it diffuses in the radial direction and passes from the inside of the filter to the outside of the filter. . The refrigerant gas inflow operation is performed using the difference between the pressure on the compression portion side of the high pressure portion provided in the scroll of the compressor 100 and the pressure in the container 5 </ b> A of the oil separator 5. The refrigerant gas that has passed through the filter flows into the suction side of the heat exchanger 6 after flowing in from the proximal end portion of the outflow pipe 1B installed on the upper side in the container 5A.

  On the other hand, the refrigerant gas sews through the holes of the perforated plate while colliding with the perforated plate, and the oil separated from the refrigerant gas adheres to the filter surface and travels to the bottom of the container 5A by its own weight in the course of such collision and friction. Dropped (dripped).

  The float 52 rotates so that the vertical position fluctuates in conjunction with the upward / downward displacement operation of the oil level stored in the bottom of the container 5A. The float valve 53 opens and closes according to the rotation of the float 52. In other words, when the oil level rises to a predetermined level set in advance, the float valve 53 is mechanically interlocked with the raising operation. Then, the valve is configured to open.

  The oil pipe 54 is disposed so as to communicate between the float type valve 53 installed at the lower part in the container 5A and the outside on the upper side of the container 5A, and the pressure inside the container 5A and the sealing of the compressor 100 are sealed. Using the difference with the pressure of the low pressure chamber 112 in the container 141, the oil stored in the bottom of the container 5A is sucked and discharged to the outside of the container 5A. Since the oil pipe 54 is installed in such an arrangement, when a small amount of oil is stored in the lower part of the container 5A, the oil can be supplied from the oil return circuit 23, and the closed oil pipe No oil is discharged from 54.

  The oil return circuit 23 has a terminal portion connected to the tip of the oil pipe 54 and a terminal portion connected to the bottom side in the hermetic container 101 of the compressor 100. Is supplied to the bottom of the hermetic container 101 of the compressor 100 only when a predetermined amount or more is stored. Therefore, as described above, when a small amount of oil is stored in the lower portion of the container 5A, the oil can be supplied only from the oil injection circuit 22.

  The liquid injection circuit 21 is installed to cool the compression space 125 by the liquid refrigerant that has been cooled or supercooled when detecting a temperature rise in the compression space 125 that constitutes the high-pressure compression chamber of the compressor 100. Yes. The liquid injection circuit 21 outputs a part of the liquid refrigerant (or a part of the liquid refrigerant accumulated in the receiver tank 7) supercooled by the supercooler 8 after leaving the receiver tank 7 to the compressor 100. The scroll compression element is supplied to a compression space 125 constituting a compression chamber of a low pressure portion or an intermediate pressure portion.

  As shown in FIG. 2, the liquid injection circuit 21 of the present embodiment includes a low-pressure unit that constitutes a compression chamber of a scroll compression element of the compressor 100, part of the liquid refrigerant supercooled by the supercooler 8, Of the compression space 125 consisting of the three chambers of the intermediate pressure portion and the high pressure portion, the compression space 125 is fed into the compression space 125 of the intermediate pressure portion. Further, the liquid injection circuit 21 of the present embodiment is provided with a service valve 21S, a strainer 21C, a first electromagnetic valve 21A, a solenoid 21D, and the like. In the liquid injection circuit 21 having such a configuration, the temperature of the refrigerant gas discharged upward from the discharge hole 113 is detected by the temperature detection unit 60, and when the detected temperature exceeds a predetermined set temperature, the solenoid 21D is turned on and the first is detected. The amount of opening of the solenoid valve 21A is controlled, and the supercooled refrigerant is sent into the compression space 125, which is a compression chamber.

As described above, the temperature detection unit 60 is housed in the distal end portion of the pipe P that penetrates the upper wall of the sealed container 101 and the cover 127 shown in FIG. 1, and the refrigerant gas discharged upward from the discharge hole 113. Detect temperature. The temperature information detected by the temperature detection unit 60 is output to the control unit 24. The control unit 24, based on this temperature information, for example, when the temperature at an outlet not shown exceeds a predetermined temperature, 1 the third control signal I ₃ for operating the solenoid 21D is outputted to the first control signal I ₁ of the solenoid valve 21A open is output.

  The oil injection circuit 22 uses the oil separated from the refrigerant by the oil separator 5 into which the refrigerant discharged after being discharged out of the scroll of the compressor 100 flows into the compression space 125 of the low pressure portion or the intermediate pressure portion of the scroll compression element 102. This supply is performed when the refrigerant evaporation temperature of the evaporator falls below a predetermined temperature.

  That is, when the evaporation temperature of the refrigerant becomes an extremely low temperature, for example, −40 ° C. or less, the circulation amount of the refrigerant decreases due to an increase in the throttle amount in the decompression device 13, and at the same time, the refrigerant is mixed in the refrigerant. The amount of oil circulation is also reduced. Therefore, the oil separated from the refrigerant by the oil separator 5 and sent out through the oil injection circuit 22 is merged with the refrigerant liquid sent out to the downstream side of the liquid injection circuit 21, thereby the compressor. The oil for lubrication is simultaneously supplied to the compression space 125 of the low pressure part or the intermediate pressure part of 100 scroll compression elements. In the present embodiment, as described above, the tip of the liquid injection circuit 21 (at the same time, the oil injection circuit 22 is the same) is connected to the compression space 125 of the intermediate pressure portion of the scroll compression element 102. Then, you may connect with the compression space 125 of the low voltage | pressure part of the scroll compression element 102. FIG.

  The oil injection circuit 22 of the present embodiment is connected between the bottom (particularly, the lowermost part) of the oil separator 5 shown in FIG. 3 and the discharge side of the solenoid 21D of the liquid injection circuit 21, and a capillary tube 22A, A second electromagnetic valve 22B is provided.

  Thus, since the tip of the oil injection circuit 22 is connected to the bottom of the oil separator 5, particularly the lowest part, the amount of oil stored in the bottom of the oil separator 5 in the container 5 </ b> A is small. However, the oil can be supplied to the compression space 125 of the low pressure part or the intermediate pressure part of the scroll compression element of the compressor 100. In other words, unlike the oil return circuit 23, as long as the oil is stored in the bottom of the container 5A of the oil separator 5 regardless of the amount of oil stored in the bottom of the container 5A, the oil injection It can be supplied from the circuit 22 to the compression space 125 of the scroll compression element 102 of the compressor 100.

  The capillary tube 22A allows the oil separated from the refrigerant by the oil separator 5 to pass through a passage in which the inside of the tube is extremely narrow, thereby preventing an excessive supply of oil passing through the tube, and a constantly stable flow rate. Take control.

The second electromagnetic valve 22B is controlled to be opened by the control unit 24. That is, the control unit 24 detects the internal temperature of the low-pressure chamber 112 via a pressure signal from the low-pressure sensor 25 that detects the internal pressure of the low-pressure chamber 112 of the compressor 100, and this temperature falls below a predetermined set value. happens when, for outputting a second control signal I ₂ and the third control signal I ₃ for on-operation of the solenoid 21D valve opening of the second solenoid valve 22B. As a result, by supplying oil to the compression space 125 of the intermediate pressure portion of the scroll compression element 102 of the compressor 100 together with the refrigerant on the liquid injection circuit 21 side, the oil that is deficient in the scroll compression space 125 is reduced. Replenishment is made to prevent burning on the scroll.

  As for the detection method for detecting the internal temperature of the low pressure chamber 112 of the compressor 100 from the pressure information from the low pressure sensor 25, the refrigerant pressure P (saturation pressure, absolute pressure) and enthalpy stored in the control unit 24 are used. Temperature detection is performed because the temperature corresponding to the detected pressure value is calculated based on the PH diagram (that is, the Mollier diagram) indicating the correlation with H.

  The oil return circuit 23 collects the oil separated from the refrigerant by the oil separator 5 into the sealed container 101 of the compressor 100, and the oil is stored in the bottom of the oil separator 5 in a predetermined amount or more as described above. At the time, the bottom of the sealed container 101 is refueled.

  The control unit 24 is connected to the temperature detection unit 60 accommodated at the tip of the pipe P that passes through the upper wall of the sealed container 101 and the cover 127, and the output is connected to the solenoid 21D of the liquid injection circuit 21 and the second output. 1 It is connected to the solenoid valve 21A. The control unit 24 is also connected to a low pressure sensor 25 that detects the internal pressure of the low pressure chamber 112 of the compressor 100 and has an output connected to the second electromagnetic valve 22B of the oil injection circuit 22. Has been.

Next, the scroll compressor 100 provided in the refrigerant circuit 1 according to the present embodiment will be described in detail.
In FIG. 2, the scroll compressor 100 is of an internal low pressure type, and includes a vertical cylindrical sealed container 101 made of a steel plate. The sealed container 101 includes a container main body 101A having a vertically long cylindrical shape, an end cap 101B (upper in the figure) and a bottom cap 101C (in the figure) each having a substantially bowl shape fixed by welding to both ends (upper and lower ends) of the container main body 101A. (Lower part in the figure). Hereinafter, the end cap 101B side and the bottom cap 101C side of the sealed container 101 will be described below.

  In the sealed container 101, an electric element 103 as a driving means is stored on the lower side, and a scroll compression element 102 driven by a rotating shaft 105 of the electric element 103 is stored on the upper side. An upper support frame 104 (main frame) is accommodated between the scroll compression element 102 and the electric element 103 in the hermetic container 101. The upper support frame 104 has a bearing portion 106 and a boss accommodating portion 122 in the center. And are formed.

  This bearing portion 106 is for pivotally supporting the tip (upper end) side of the rotating shaft 105 and is formed to project downward from the center of one surface (lower surface) of the upper support frame 104. Yes. The boss accommodating portion 122 is for accommodating a boss 124 of a swing scroll 115 described later, and is formed by recessing the center of the other surface (upper surface) of the upper support frame 104 downward. Yes.

  A lower support frame 107 (bearing plate) is accommodated in the sealed container 101 below the electric element 103, and a bearing 108 is formed at the center of the lower support frame 107. This bearing 108 is for supporting the end (lower end) side of the rotating shaft 105 and is formed to project downward from the center of one surface (lower surface) of the lower support frame 107. . A space below the lower support frame 107, that is, a bottom portion in the sealed container 101 is an oil sump 162 in which lubricating oil for lubricating the scroll compression element 102 and the like is stored.

  An eccentric shaft 123 is formed at the tip (upper end) of the rotating shaft 105. The eccentric shaft 123 is provided so that the center thereof is eccentric from the axis of the rotary shaft 105, and the swing scroll 115 can be driven to swing on the boss 124 of the swing scroll 115 via a slide bush and a swing bearing (not shown). Has been inserted.

  The scroll compression element 102 includes a fixed scroll 114 and a swing scroll 115. The fixed scroll 114 includes a circular end plate 116, an involute erection erected on one surface (lower surface) of the end plate 116, or a spiral wrap 117 having a curve similar thereto, A peripheral wall 118 erected so as to surround the periphery of the wrap 117, and protruded around the peripheral wall 118 (the other surface side (upper side) of the peripheral wall 118). A flange 119 that is shrink-fitted on the inner surface is integrally formed.

  In the fixed scroll 114, the flange 119 is shrink-fitted and fixed to the inner surface of the container body 101A, and the refrigerant gas compressed by the scroll compression element 102 is placed in the center of the end plate 116 (the center of the fixed scroll 114). A discharge hole 113 communicating with a discharge pressure space 111 (muffler chamber) formed in the upper side of the sealed container 101 is formed. The fixed scroll 114 has the wrap 117 protruding downward.

  The electric element 103 includes a stator 150 fixed to the hermetic container 101 and a rotor 152 that is disposed inside the stator 150 and rotates within the stator 150. A rotating shaft 105 is fitted at the center. The stator 150 is formed of a laminated body in which a plurality of electromagnetic steel plates are laminated, and has a stator winding 151 wound around a tooth portion of the laminated body. The rotor 152 is also formed of a laminate of electromagnetic steel plates, like the stator 150.

  An oil passage 105A is formed in the rotation shaft 105 along the axial direction of the rotation shaft 105. The oil passage 105A includes a suction port 161 located at the lower end of the rotation shaft 105, and the suction passage The port 161 is immersed in the lubricating oil stored in the oil sump 162 and opened in the lubricating oil. The oil passage 105 </ b> A is formed with an oil supply port for supplying lubrication at a position corresponding to each bearing. With this configuration, when the rotating shaft 105 rotates, the lubricating oil stored in the oil sump 162 is transferred to the rotating shaft 105. The oil passage 105A enters from the suction port 161 and is pumped upward. Then, the pumped-up lubricating oil is supplied to each bearing and the sliding portion of the scroll compression element 102 through each oil supply port.

  The airtight container 101 is compressed by a refrigerant suction pipe 145 for introducing a refrigerant into a lower space 112 (hereinafter referred to as a low pressure chamber 112) in the airtight container 101, and a scroll compression element 102, A refrigerant discharge pipe 146 for discharging the refrigerant discharged from the discharge hole 113 to the upper discharge pressure space 111 in the sealed container 101 through a discharge muffler chamber 128 described later is provided. In this embodiment, the refrigerant suction pipe 145 is welded and fixed to the side surface of the container body 101A of the sealed container 101, and the refrigerant discharge pipe 146 is fixed to the side surface of the end cap 101B by welding.

  On the other hand, in the configuration of the present embodiment, the upper surface 130 (the surface opposite to the wrap 117) of the end plate 116 of the fixed scroll 114 is configured to face the discharge pressure space 111 formed on the upper side in the sealed container 101. . On the upper surface 130 of the end plate 116 of the fixed scroll 114, a discharge valve (not shown) connected to the discharge hole 113 and a plurality of release valves are provided adjacent to the discharge valve (the discharge valve and the release valve). Neither is shown). The release valve is provided to prevent overcompression of the refrigerant, and communicates with the compression space 125 in the compression process via a release port (not shown).

  A cover 127 screwed to the fixed scroll 114 is provided in the discharge pressure space 111 on the upper side of the sealed container 101. At the center of the lower surface of the cover 127, a discharge muffler chamber 128 is formed that is recessed from the fixed scroll 114 side toward the discharge pressure space 111 and forms a muffler chamber together with the discharge pressure space 111. The discharge muffler chamber 128 communicates with the discharge hole 113, and although not shown, the discharge muffler chamber 128 and the discharge pressure space 111 in the upper side of the sealed container 101 are connected through a gap provided between the cover 127 and the fixed scroll 114. Are communicating.

  Specifically, when the refrigerant pressure in the compression process reaches the discharge pressure before reaching the discharge hole 113, the release valve is opened, and the refrigerant in the compression space 125 is discharged to the outside through the release port. Become.

  The rocking scroll 115 is a scroll that revolves with respect to the fixed scroll 114 that is shrink-fitted and fixed to the inner surface of the container main body 101A as described above. The disk-shaped end plate 120 and one surface (upper side) A spiral wrap 121 having an involute shape or a curve approximated thereto, and the above-mentioned boss 124 protruding from the other surface (lower surface) of the end plate 120. It consists of and. The oscillating scroll 115 is arranged so that the protruding direction of the wrap 121 is upward and the wrap 121 is rotated 180 degrees to the wrap 117 of the fixed scroll 114 so as to face each other. 125 is formed.

  That is, the wrap 121 of the orbiting scroll 115 is opposed to the wrap 117 of the fixed scroll 114 and meshes so that the front end surfaces of both wraps 121 and 117 are in contact with the bottom surfaces (end plate 116 and end plate 120). In addition, the orbiting scroll 115 is fitted to an eccentric shaft 123 that is eccentric from the axis of the rotary shaft 105. For this reason, the compression space 125 creates a plurality of spaces in which the two spiral wraps 121 and 117 are decentered from each other and are in contact with each other on the line in the eccentric direction, and each of these spaces is a compression chamber (low pressure portion, A plurality of compression spaces such as an intermediate pressure portion and a high pressure portion).

  The fixed scroll 114 has a flange 119 provided around the peripheral wall 118 fixed to the upper support frame 104 via a plurality of bolts (not shown). The swing scroll 115 is supported on the upper support frame 104 by an Oldham ring 148 and an Oldham mechanism 149 including an Oldham key. Thus, the orbiting scroll 115 is configured to perform a turning motion without rotating with respect to the fixed scroll 114.

  Since the orbiting scroll 115 revolves eccentrically with respect to the fixed scroll 114, the eccentric direction and contact position of the two spiral wraps 117 and 121 move while rotating, and the compression chamber is compressed from the outside to the inside. It gradually shrinks while moving toward the space 125. The low-pressure refrigerant gas that first enters from the outer compression space 125 and is confined in the low-pressure portion gradually moves inward while being adiabatically compressed, passes through an intermediate pressure (intermediate pressure portion), and finally reaches the central portion (high-pressure portion). When it reaches, it becomes a high-temperature and high-pressure refrigerant gas. The refrigerant gas is sent out to the discharge pressure space 111 through the discharge hole 113 formed at the center of the fixed scroll 114 and the discharge muffler chamber 128.

  In the cover 127 (inside the plate pressure of the cover 127), the liquid refrigerant in the receiver tank 7 (see FIG. 1) is returned to the intermediate pressure portion of the scroll compression element 102 and evaporated to cool the compressed gas. A liquid injection passage 144 (corresponding to the liquid injection circuit 21 of the present invention) for carrying out is formed (shown in FIG. 2).

  The liquid injection passage 144 branches in the cover 127 and is connected to injection holes 141 and 142 described later. The liquid injection passage 144 is connected to a pipe 140 formed of a hollow tube. One end of the pipe 140 is press-fitted into the liquid injection passage 144 of the cover 127 and the other end is a sleeve 139. Is fixed to the end cap 101B by welding.

  Further, the above-described injection holes 141 and 142 communicating with the liquid injection passage 144 are formed through the end plate 116 of the fixed scroll 114 in the vertical direction. The lower side of both the injection holes 141 and 142 (the swinging scroll 115 side) opens to the wrap 117 and 121 side, and the intermediate pressure portion of the scroll compression element 102 (the discharge hole 113 formed at the center of the fixed scroll 114). The intermediate pressure portion communicates immediately before reaching the same compression space 125 or in the vicinity thereof. The pipe 140 is attached across the end cap 101B and the cover 127, and the liquid injection circuit 21 from the receiver tank 7 shown in FIG. 1 is connected to the connection pipe 147 connected to the pipe 140, so that the liquid injection passage is provided. 144 is formed.

  The one injection hole 141 is formed at a position shifted from the other injection hole 142 by 180 degrees with reference to the center of the fixed scroll 114 as shown in FIGS. One injection hole 141 is formed on the outer side of the wrap 117 erected on the fixed scroll 114 (the high compression chamber formed on the inner side of the wrap 121 of the swing scroll 115, that is, on the compression space side of the high pressure portion). The other injection hole 142 is formed inside the wrap 117 erected on the fixed scroll 114 (a high compression chamber formed outside the wrap 121 of the swing scroll 115, that is, the compression space side of the high pressure portion). Yes.

Next, the operation of this embodiment will be described.
First, the operation of the scroll compression element 102 in the compressor 100, particularly the compressed gas cooling operation will be described. Here, although details will be described later, when the controller 24 detects that the discharged refrigerant temperature has exceeded a predetermined temperature via the temperature detector 60, the controller performs the following steps. Under the control of 24, the liquid refrigerant in the receiver tank 7 is returned to the intermediate pressure portion of the scroll compression element 102 via the liquid injection circuit 21, and evaporated to cool the compressed gas.

  Here, for convenience of explanation, it is assumed that the orbiting scroll 115 is first positioned near the final compression stroke. At that time, the injection holes 141 and 142 are completely closed by the wrap 121 of the orbiting scroll 115 (first step; see FIG. 4A).

  When the orbiting scroll 115 revolves, both the injection holes 141 and 142 closed by the wrap 121 of the orbiting scroll 115 are positioned immediately before opening to the intermediate pressure portion (compression space 125) ( Second step; see FIG. 4B). At this time, the discharge of the high-temperature and high-pressure refrigerant gas from the high-pressure portion (compression space 125) to the discharge hole 113 is completed or is in a state immediately before the end.

  Further, as the orbiting scroll 115 revolves, the wrap 121 of the orbiting scroll 115 is separated from both the injection holes 141 and 142, and the both injection holes 141 and 142 are opened to the intermediate pressure portion (compression space 125). (Third step; see FIG. 4C). At this time, the liquid refrigerant in the receiver tank 7 returns to the compression space 125 of the intermediate pressure portion of the scroll compression element 102 via the liquid injection circuit 21 and evaporates to cool the compressed gas. Then, when the orbiting scroll 115 further revolves, it returns and repeats the (first step), (second step), and (third step). In this way, the cooling operation for the high-temperature and high-pressure compressed gas is performed using the evaporating action of the liquid refrigerant sent from the receiver tank 7 through the liquid injection circuit 21.

  Next, the ultra-low temperature refrigeration apparatus according to the present embodiment includes the oil return circuit 23 as described above. Therefore, when the refrigerant discharged from the sealed container 141 (see FIG. 2) flows into the oil separation means 51 of the oil separator 5 through the inflow pipe 1A shown in FIG. 3, only the oil mixed in the refrigerant is separated. It is stored at the bottom in the container 5A.

  When the amount of stored oil gradually increases and the float 52 for detecting the oil level at the bottom of the oil separator 5 is detected to exceed a required level, the float valve 53 is opened. As a result, oil is sucked into the oil return circuit 23 through the float valve 53 and the oil pipe 54 that are opened.

  Thereby, the oil flowing out from the oil separator 5 through the oil pipe 54 is supplied to the oil sump at the inner bottom portion of the sealed container 101 via the oil return circuit 23, and the oil shortage in the oil sump 162 can be solved. On the other hand, the refrigerant from which the oil has been separated and removed by the oil separation means 51 shown in FIG. 3 is sent from the outflow pipe 1B to the heat exchanger 6 shown in FIG. 1 to be condensed.

  Therefore, according to the present embodiment, the oil is returned to the inside of the compressor 100 through the oil return circuit 23 that communicates between the oil separator 5 and the lower portion of the compressor 100, and thus is generated in the compression space 125. Oil shortage can be resolved.

In addition, the present embodiment includes a liquid injection circuit 21. In the scroll type ultra-low temperature compressor 100, the control unit 24 detects that the temperature detection unit 60 has risen above a predetermined set temperature. Control the operation. Then, the solenoid 21D is turned on by the third control signal I ₃ to be output from the control unit 24, the first control signal I ₁ opens the first electromagnetic valve 21A, the liquid refrigerant is subcooled in subcooler 8 A part is supplied to the compression space 125 of the intermediate pressure part (or low pressure part) of the scroll compression element via the liquid injection circuit 21 to suppress the temperature rise of the scroll compression element.

  In this case, when the detected temperature exceeds the set temperature by the control operation of the control unit 24 performed according to the detected temperature of the temperature detecting unit 60, that is, when the temperature difference from the detected temperature is large, the flow rate of the liquid refrigerant is large and the detection is performed. When the temperature difference from the temperature is small, the flow rate of the liquid refrigerant by the first electromagnetic valve 21A is adjusted so that the flow rate of the liquid refrigerant decreases. The supply of the liquid refrigerant to the compression space 125 of the intermediate pressure portion (or low pressure portion) of the scroll compression element is in the supercooler 8 than the compression space 125 of the low pressure portion (or intermediate pressure portion) of the scroll compression element. This is performed by the pressure difference due to the high pressure. This suppresses the temperature rise of the scroll compression element.

  Moreover, the ultra-low temperature refrigeration apparatus according to the present embodiment is operated at an ultra-low temperature of −40 ° C. or lower, for example, −60 ° C., and includes the oil injection circuit 22 as described above. Therefore, based on the output signal from the low pressure sensor 25 (see FIG. 1) that detects the internal pressure of the low pressure chamber 112 (see FIG. 2) in the sealed container 141 of the compressor 100, the pressure of the refrigerant stored by the control unit 24. The temperature is detected by calculating the temperature corresponding to the detected pressure value based on the PH diagram (that is, the Mollier diagram) indicating the correlation between P (saturation pressure, absolute pressure) and enthalpy H.

  When the detected internal temperature of the low-pressure chamber 112 inside the sealed container 141 is lower than a predetermined value, the second electromagnetic valve 22B is opened by a control signal from the control unit 24. Therefore, the oil from the bottom of the oil separator 5 that is adjusted so that the flow rate is sent out almost constant amount through the capillary tube 22A provided in the oil injection circuit 22 passes through the opened second electromagnetic valve 22B. . The oil after passing through the second electromagnetic valve 22B is supplied to the compression space 125 of the intermediate pressure portion of the scroll compression element 2 through a common pipe where the oil injection circuit 22 and the liquid injection circuit 21 merge. This oil supply operation is performed until the internal temperature of the low-pressure chamber 112 rises and reaches a predetermined temperature.

  Thereby, the temperature increase of the scroll compression element is suppressed by the supercooled refrigerant supply by the liquid injection circuit 21, and at the same time, the oil shortage of the scroll compression element is eliminated by the oil supply by the oil injection circuit 22 and the scroll operation is performed. This maintains the lubrication.

Therefore, according to the oil separator 5 of the present embodiment, when the amount of oil stored in the oil separator 5 exceeds a predetermined level, the differential pressure is used automatically to the inner bottom portion of the sealed container 141 of the compressor 100. It can be recovered. That is, when oil is stored at a predetermined level or more in the inner bottom portion of the container 5A of the oil separator 5, it is possible to reliably and automatically automate oil collection to the inner bottom portion of the sealed container 141 of the compressor 100 at a low cost.
In addition, an ultra-low temperature refrigeration apparatus including the oil separator 5 that can reliably and automatically realize oil recovery simply and at low cost can be provided.

In addition, this invention is not limited to the said embodiment, A various deformation | transformation implementation is possible in the range which does not deviate from the summary as described in a claim.
For example, in this embodiment, the temperature detection related to the oil injection circuit 22 is calculated by the control unit 24 based on the internal pressure of the low pressure chamber R in the hermetic container 141 of the compressor 100 based on the pressure detection of the low pressure sensor 25. Although it is a structure, it is not limited to this in particular. For example, the structure which measures the refrigerant | coolant temperature of an evaporator directly may be sufficient. Moreover, the refrigerant | coolant evaporation temperature by the ultra-low temperature freezing apparatus of this invention is predetermined temperature below -40 degreeC, Comprising: Although it sets to -40 degreeC or -45 degreeC in this embodiment, it is not limited to this temperature in particular.

  Furthermore, in the present embodiment, the refrigerant after passing through the supercooler 8 is configured to be sent to the compression space 125 of the intermediate pressure portion of the scroll compression element of the compressor 100 via the liquid injection circuit 21. Not limited to this. That is, for example, as shown by a broken line in FIG. 1, this liquid injection circuit 21 ′ is placed between the discharge side of the receiver tank 7 and the compression space of the intermediate pressure portion (or low pressure portion) of the scroll compression element of the compressor 100. It may be installed.

  Further, in the present embodiment, the oil separator 5 that can realize oil recovery automatically and reliably at low cost is provided in the ultra-low temperature refrigeration apparatus. In the present invention, this oil separator is particularly used in the ultra-low temperature type refrigeration apparatus. It is not necessary to equip with limitation, and you may equip with a general freezing apparatus normally.

1 Refrigerant circuit (refrigerant circulation circuit)
1A Inflow pipe 1B Outflow pipe 11, 12 Inter-unit piping 13 Pressure reducing device (expansion valve)
14 Heat exchanger (evaporator)
2 Strainer 21 Liquid Injection Circuit 21A First Solenoid Valve 21D Solenoid 22 Oil Injection Circuit 22B Second Solenoid Valve 23 Oil Return Circuit (Oil Return Pipe)
24 control unit 25 low pressure sensor 3 accumulator 100 compressor (scroll type ultra-low temperature compressor)
102 Scroll compression element 103 Electric element 105 Rotating shaft 105A Oil passage 111 Discharge pressure space 112 Low pressure chamber 113 Discharge hole (discharge port)
114 Fixed scroll 115 Swing scroll 117, 121 Lap 125 Compression space (intermediate pressure part, low pressure part; compression chamber)
128 Discharge muffler chamber 141 Sealed container 142 Cover 162 Oil sump 5 Oil separator 5A Container 51 Oil separation means 52 Float 53 Float type valve 54 Oil pipe 6 Heat exchanger (condenser)
60 Temperature detector 7 Receiver tank 8 Supercooler P Pipe

Claims (1)

An electric element and a scroll compression element driven by the electric element are accommodated in a hermetic container, a lower space of the scroll compression element in the hermetic container is a low pressure chamber, and the upper part of the scroll compression element in the hermetic container The space is used as a discharge pressure space for refrigerant gas compressed by the scroll compression element, and the discharge pressure space is discharged from the discharge port while compressing the refrigerant gas sucked from the suction pipe communicating with the scroll compression element by the scroll compression element. A scroll compressor that discharges the refrigerant gas discharged to the outside of the sealed container,
The discharged refrigerant gas passes through a condenser and a receiver tank that stores liquid refrigerant, and after evaporating liquid refrigerant decompressed and expanded by an expansion valve using an evaporator, returns to the scroll compression element from the suction pipe again. Forming a circulation circuit,
An oil separator is installed on the refrigerant circuit in which the refrigerant gas discharged from the scroll compression element of the compressor is sent to the condenser outside the sealed container,
An oil return circuit for returning oil stored in the oil separator into the sealed container;
A part of the liquid refrigerant accumulated in the receiver tank or a part of the liquid refrigerant obtained by supercooling the refrigerant exiting the receiver tank with a supercooler is supplied to the compression chamber of the low pressure part or the intermediate pressure part of the scroll compression element. An oil injection circuit for supplying the oil separated from the refrigerant by the oil separator to the compression chamber of the low pressure part or the intermediate pressure part of the scroll compression element,
A low pressure sensor for detecting the internal pressure of the low pressure chamber is provided, and the control unit calculates the correlation between the pressure of the refrigerant and the enthalpy based on the output signal from the low pressure chamber, and calculates the correlation of the low pressure chamber. When the internal temperature is lower than the predetermined value, the solenoid valve provided in the oil injection circuit is opened, and the oil is compressed until the internal temperature of the low pressure chamber reaches the predetermined temperature. In an ultra-low temperature refrigeration system that cools to an ultra-low temperature of −40 ° C. or less supplied to a room,
The oil separator is
The refrigerant gas discharged from the scroll compression element is installed on a refrigerant circuit that is sent out of the sealed container,
A container that is long in the vertical direction,
Oil separating means installed on the upper side in the container;
A refrigerant delivery pipe for delivering the refrigerant gas separated by the oil separation means to the outside of the container;
A float that rises and falls according to the amount of oil separated and dropped by the oil separating means and stored in the bottom of the container;
A float valve that operates when the float rises above a predetermined level set in advance;
When the liquid level of the oil stored in the bottom of the container exceeds a predetermined level, the float valve is opened, and the oil stored in the bottom of the container is sucked and sent to the outside of the container. An oil return pipe for returning oil,
And the tip of the oil injection circuit is connected to the lowest part in the container
An ultra-low temperature refrigeration apparatus.

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