WO2014168117A1 - Heat pump unit and heat pump unit operation method - Google Patents

Abstract

This heat pump unit (200) is provided with the following: a circulation path (210) in which a heat medium circulates; a compressor (230) that has an accommodation space (R) for accommodating a lubrication oil supplied to a compressor mechanism (232, 234), and that insulates and compresses the heat medium so as to elevate the temperature thereof; a condenser (240) that condenses the heat medium; an expansion valve (260) that reduces the pressure of and expands the heat medium; an evaporator (220) that vaporizes the heat medium; and a control unit (280) that controls the driving of the compressor and the degree of opening of the expansion valve. The control unit is configured so that, upon receiving an instruction for stopping the compression operation of the compressor, the control unit makes the degree of opening of the expansion valve smaller so as to maintain the height of the liquid surface of the lubrication oil accommodated in the accommodation space at at least a threshold value determined in advance, and stops the operation of the compressor after the expansion valve has completely closed.

Description

HEAT PUMP UNIT AND HEAT PUMP UNIT OPERATION METHOD

The present invention relates to a heat pump unit and a method for operating the heat pump unit.
This application claims priority based on Japanese Patent Application No. 2013-082117 for which it applied to Japan on April 10, 2013, and uses the content here.

Conventionally, a compressor that adiabatically compresses and heats a heat medium circulating in a circulation path, a condenser that condenses the heat medium by cooling the heat medium heated by the compressor, and a heat medium condensed by the condenser 2. Description of the Related Art A heat pump unit is known that includes an expansion valve that cools by decompressing and cooling an evaporator, and an evaporator that vaporizes the heat medium by heating the heat medium cooled by the expansion valve. Such a heat pump unit is used in various fields such as a refrigerator, a freezer, an air conditioner, and a water heater.

When stopping the operation of such a heat pump unit, for example, when the drive of the compressor is stopped without closing the expansion valve, the liquid heat medium remains in the evaporator. In this case, when the operation of the heat pump unit is started next, the liquid heat medium remaining in the evaporator is directly introduced into the compressor, which may cause a malfunction.

Therefore, when stopping the operation of the heat pump unit having an expansion valve that can be controlled on and off, a technique is disclosed in which the expansion valve is fully closed at one time before the drive of the compressor is stopped (see, for example, Patent Document 1). ).

Japanese Unexamined Patent Publication No. 2001-165511

Lubricating oil is supplied to the compression mechanism constituting the compressor. When the compressor adiabatically compresses the heat medium in the heat pump unit, the heat medium may be dissolved in the lubricating oil. In this case, when the expansion valve is fully closed at a time while the compressor is driven using the technique of Patent Document 1, the pressure in the compressor is rapidly reduced, and the heat medium dissolved in the lubricating oil is foamed. there's a possibility that.

When the heat medium is foamed, the apparent viscosity of the lubricating oil is lowered, and the oil film of the lubricating oil is not sufficiently formed in the compression mechanism, and the wear of the compression mechanism is promoted, and the compressor may be damaged.

An object of the present invention is to provide a heat pump unit and a heat pump unit operating method capable of suppressing foaming of a heat medium contained in lubricating oil and preventing damage to the compressor when the compressor is stopped. It is.

In order to solve the above problems, in the first aspect of the present invention, the heat pump unit has a circulation path through which the heat medium circulates, a compression mechanism, and a storage space for storing lubricating oil supplied to the compression mechanism. And a compressor that adiabatically compresses the heat medium circulating in the circulation path and raises the temperature, and a heat medium that is provided downstream of the compressor in the circulation path and cools the heat medium heated by the compressor to condense the heat medium A condenser, an expansion valve provided downstream of the condenser in the circulation path and decompressing and cooling the heat medium condensed by the condenser; and provided downstream of the expansion valve in the circulation path and cooled by the expansion valve. An evaporator that evaporates the heat medium by heating the heat medium, and a controller that controls the drive of the compressor and the opening of the expansion valve to control the circulation amount of the heat medium in the circulation path. Further, when the control unit receives an instruction to stop the compression operation of the heat medium by the compressor, the level of the lubricating oil stored in the storage space is equal to or higher than a threshold set in advance in the compressor. In order to maintain the value of the expansion valve, the opening of the expansion valve is reduced, the expansion valve is fully closed and the flow of the heat medium into the compressor through the expansion valve is shut off, and then the heat medium is compressed by the compressor. Is configured to stop.

In the second aspect of the present invention, in the heat pump unit of the first aspect, the control unit opens the expansion valve so that the rate of change of the opening degree of the expansion valve is maintained at a predetermined first value. By reducing the degree, the height of the level of the lubricating oil stored in the storage space is maintained at a value equal to or higher than the threshold value.

In the third aspect of the present invention, in the heat pump unit of the first aspect, the control unit opens the expansion valve so that the rate of decrease in the pressure of the accommodation space is maintained at a predetermined second value. The height of the liquid level of the lubricating oil stored in the storage space is maintained at a value equal to or higher than the threshold value by reducing the value of.

In the fourth aspect of the present invention, in the heat pump unit according to any one of the first to third aspects, the control unit fully heats the expansion valve, and then the heat in which the pressure in the accommodation space is contained in the lubricating oil. The compression operation of the heat medium by the compressor is continued until the pressure becomes lower than the pressure corresponding to the predetermined concentration of the medium, and the pressure in the housing space corresponds to the predetermined concentration of the heat medium contained in the lubricating oil. When the pressure is lower than the pressure, the compression operation of the heat medium by the compressor is stopped.

In order to solve the above-mentioned problem, in a fifth aspect of the present invention, the operation method of the heat pump unit includes a circulation path through which a heat medium circulates, a compression mechanism, and a storage space for storing lubricating oil supplied to the compression mechanism. And a compressor that adiabatically compresses and heats the heat medium circulating in the circulation path, and a heat medium that is provided downstream of the compressor in the circulation path and cools the heat medium heated by the compressor A condenser that condenses the refrigerant, an expansion valve that is provided downstream of the condenser in the circulation path, cools the heat medium condensed by the condenser by decompression, and is provided downstream of the expansion valve in the circulation path. And an evaporator that evaporates the heat medium by heating the heat medium cooled by the heat pump unit. In this operation method, when an instruction to stop the compression operation of the heat medium by the compressor is received, the liquid level of the lubricating oil accommodated in the accommodation space is equal to or higher than a threshold set in advance in the compressor. To maintain the value, reduce the expansion valve opening, fully close the expansion valve to shut off the flow of heat medium to the compressor through the expansion valve, and then stop the heat medium compression operation by the compressor To do.

According to the present invention, when the compressor is stopped, foaming of the heat medium contained in the lubricating oil can be suppressed and damage to the compressor can be prevented.

It is a conceptual diagram for demonstrating a vacuum cleaning apparatus. It is a figure for demonstrating the structure of a compressor. It is a flowchart for demonstrating the flow of a process of the operating method of a heat pump unit.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

Conventionally, heat pump units are installed in various electric devices such as refrigerators, freezers, air conditioners, and water heaters. In recent years, a vacuum cleaning apparatus for cleaning a workpiece (object to be processed) under reduced pressure using a vapor of a hydrocarbon-based cleaning agent has been developed, and a heat pump unit is also used in this vacuum cleaning apparatus. The workpiece refers to, for example, an industrial product, and the vacuum cleaning apparatus cleans the workpiece and removes contaminants attached to the workpiece. In the present embodiment, a vacuum cleaning apparatus will be described as an example of an apparatus provided with a heat pump unit.

(Vacuum cleaning device 100)
FIG. 1 is a conceptual diagram (block diagram) for explaining the vacuum cleaning apparatus 100. In FIG. 1, the flow of the hydrocarbon-based cleaning agent is indicated by a solid line arrow, the flow of the heat medium is indicated by a broken line arrow, and the signal flow is indicated by a one-dot chain line arrow. As shown in FIG. 1, the vacuum cleaning apparatus 100 includes a vacuum container 104 in which a cleaning chamber 102 is provided. The vacuum container 104 has an opening (not shown), and the opening can be opened and closed by an opening / closing door (not shown). Therefore, when cleaning the workpiece W, the opening / closing door is opened, the workpiece W is loaded into the cleaning chamber 102 from the opening, the workpiece W is placed on the mounting portion 108, and the opening / closing door is closed to close the workpiece W. Wash. Thereafter, the opening / closing door is opened again, and the work W is carried out from the opening.

In the cleaning chamber 102, a shower unit 110 is provided. The steam chamber 150 is connected to the shower unit 110 through the steam supply pipe 114, the condensation chamber 120, the condensed cleaning agent supply pipe 122, the cleaning agent storage section 124, and the condensed cleaning agent supply pipe 126 in this order.

Further, the cleaning chamber 102 is provided with a steam supply unit 130. The steam supply unit 130 is communicated with the steam chamber 150 via the steam supply pipe 114.

The steam chamber 150 includes a heater 152 and a condenser 240, and the hydrocarbon-based cleaning agent (solvent) is heated to, for example, about 80 to 140 ° C, preferably about 120 ° C, and the steam of the hydrocarbon-based cleaning agent. (Hereinafter simply referred to as “steam”). The steam generated in the steam chamber 150 is introduced into the condensing chamber 120 through the steam supply pipe 114 or supplied to the cleaning chamber 102 through the steam supply unit 130. The steam supplied to the cleaning chamber 102 by the steam supply unit 130 is condensed by adhering to the workpiece W. The heating mechanism by the condenser 240 will be described in detail later.

The type of the hydrocarbon-based cleaning agent is not particularly limited, but it is desirable to use a third petroleum cleaning agent from the viewpoint of safety. For example, normal paraffin-type, isoparaffin-type, naphthene-type, and aromatic-type hydrocarbon-type detergents can be mentioned. Specifically, Teclean N20, Clean Sol G, Daphne (registered trademark) solvent or the like called a cleaning solvent may be used as a cleaning agent for third petroleums.

The condensation chamber 120 includes an evaporator 220. The vapor introduced into the condensation chamber 120 is cooled by the evaporator 220 and condensed into a liquid hydrocarbon-based cleaning agent (hereinafter simply referred to as “condensed cleaning agent”). The condensed cleaning agent is stored in the cleaning agent storage unit 124 through the condensed cleaning agent supply pipe 122 and then supplied to the cleaning chamber 102 through the condensed cleaning agent supply pipe 126 and the shower unit 110. The cooling mechanism by the evaporator 220 will be described in detail later.

The condensed cleaning agent supplied from the shower unit 110 and cleaning the workpiece W, and the condensed cleaning agent supplied from the vapor supply unit 130 and condensed in the workpiece W are passed through the used cleaning agent introduction pipe 128. It is again introduced into the steam chamber 150. The used cleaning agent introduction pipe 128 introduced into the steam chamber 150 becomes steam by being heated again by the heater 152 and the condenser 240 described above. As described above, the cleaning agent includes the steam chamber 150, the steam supply pipe 114, the condensation chamber 120, the condensed cleaning agent supply pipe 122, the cleaning agent storage section 124, the condensed cleaning agent supply pipe 126, the shower section 110, and the cleaning chamber 102. The used cleaning agent introduction pipe 128 is circulated.

Further, a vacuum pump (not shown) is connected to the cleaning chamber 102 and the steam chamber 150. This vacuum pump depressurizes the inside of the vacuum vessel 104 (cleaning chamber 102) to a predetermined pressure (for example, 6 kPa) by evacuation (initial vacuum) in a depressurization step before starting the cleaning of the workpiece W. Furthermore, a pipe (not shown) for opening the cleaning chamber 102 to the atmosphere is connected to the cleaning chamber 102. This pipe is provided with an air release valve capable of shutting off the atmosphere and the cleaning chamber 102. In the unloading process after the cleaning process and the drying process of the workpiece W are completed, the cleaning chamber 102 is opened to the atmosphere and is largely discharged. Return to atmospheric pressure.

(Heat pump unit 200)
The heat pump unit 200 includes a circulation path 210 (indicated by 210a to 210f in FIG. 1), an evaporator 220, a compressor 230, a condenser 240, an intermediate heat exchanger 250, an expansion valve 260, and pressure measurement. A unit 270 and a control unit 280 are included. In the heat pump unit 200, the heat medium circulates in the circulation path 210 as shown by the broken arrows in FIG. 1, and the evaporator 220, the intermediate heat exchanger 250, the compressor 230, and the like provided in the circulation path 210, It is again introduced into the evaporator 220 through the condenser 240, the intermediate heat exchanger 250, and the expansion valve 260. The type of the heat medium is not particularly limited, but is a CFC-based heat medium (for example, R-245fa (1) that is liquid at room temperature and atmospheric pressure and can use the latent heat of the heat medium in the evaporator 220. 1,1,3,3-pentafluoropropane)). The normal temperature is, for example, 25 ° C.

The evaporator 220 is disposed downstream of the expansion valve 260 in the circulation path 210. The evaporator 220 condenses (cools) the steam into a condensed cleaning agent by performing heat exchange between the heat medium and the hydrocarbon-based cleaning agent steam introduced from the steam chamber 150 in the condensation chamber 120. At the same time, the heat medium is heated and vaporized. That is, when heated by the evaporator 220, the heat medium becomes a gas (indicated by G in FIG. 1). The heat medium heated by the evaporator 220 is further heated by the intermediate heat exchanger 250. The heating mechanism by the intermediate heat exchanger 250 will be described in detail later.

The compressor 230 is constituted by, for example, a reciprocating compressor (reciprocating compressor), and has a compression mechanism and a storage space for storing lubricating oil supplied to the compression mechanism, and is heated by the intermediate heat exchanger 250. The heat medium is adiabatically compressed and further heated. That is, the compressor 230 heats the heat medium by adiabatically compressing it. A specific configuration of the compressor 230 will be described in detail later.

The condenser 240 is disposed downstream of the compressor 230 in the circulation path 210. The condenser 240 heats the hydrocarbon-based cleaning agent by performing heat exchange between the heat medium heated (heated up) by the compressor 230 and the liquid hydrocarbon-based cleaning agent in the vapor chamber 150. As a result, a hydrocarbon-based cleaning agent vapor is generated and the heat medium is cooled and condensed. By being cooled by the condenser 240, the heat medium is in a gas-liquid mixed state (indicated by G and L in FIG. 1).

The intermediate heat exchanger 250 has a heat medium flowing through the circulation paths 210a and 210b (between the evaporator 220 and the compressor 230) and heat flowing through the circulation paths 210d and 210e (between the condenser 240 and the expansion valve 260). Heat exchange with the medium. The heat medium heated by the evaporator 220 and flowing through the circulation path 210a may not be completely vaporized but may be a gas-liquid mixed fluid. In this case, if the heat medium in the liquid state is introduced into the compressor 230, there is a possibility that a problem occurs in the compressor 230.

Therefore, the configuration including the intermediate heat exchanger 250 heats the heat medium flowing through the circulation path 210a to a temperature higher than the saturation temperature thereof, thereby introducing the heat medium introduced into the compressor 230 (circulation through the circulation path 210b). It is possible to ensure that the heat medium is only gas. As a result, it is possible to avoid a situation in which a problem occurs in the compressor 230.

The expansion valve 260 is a valve that causes a pressure drop of the fluid. The expansion valve 260 is provided downstream of the condenser 240 and further expands the heat medium condensed (cooled) by the condenser 240 under reduced pressure for further cooling. By being cooled by the expansion valve 260, the heat medium becomes a liquid (indicated by L in FIG. 1). The heat medium cooled in the expansion valve 260 is again introduced into the evaporator 220 through the circulation path 210f.

The pressure measurement part 270 measures the pressure of the gas part in the accommodating space mentioned later in the compressor 230. FIG.

The control unit 280 is composed of a semiconductor integrated circuit including a CPU (Central Processing Unit), reads out programs and parameters for operating the CPU from the ROM, and cooperates with the RAM as a work area and other electronic circuits. The entire heat pump unit 200 is managed and controlled. In the present embodiment, the control unit 280 controls the drive amount (drive) of the compressor 230 and the opening degree of the expansion valve 260 based on the pressure measured by the pressure measurement unit 270 to circulate the heat medium in the circulation path 210. Control the amount.

As described above, the heat medium may dissolve in the lubricating oil contained in the compressor 230. Hereinafter, the effect | action which a heat medium melt | dissolves in the lubricating oil accommodated in the compressor 230 is demonstrated using FIG.

FIG. 2 is a diagram for explaining the configuration of the compressor 230. In FIG. 2, the flow of the heat medium is indicated by solid arrows, the flow of the lubricating oil is indicated by white arrows, and the lubricating oil is indicated by gray filling. As shown in FIG. 2, the piston (compression mechanism) 232 of the compressor 230 is connected to a drive shaft (compression mechanism) 234, and when the drive shaft 234 is rotationally driven by a motor (not shown), the piston 232 is Reciprocating motion is performed with respect to the compression chamber 236 (cylinder). Note that a drive device other than a motor may be used to rotationally drive the drive shaft 234. When the piston 232 is positioned near its bottom dead center, the heat medium is introduced from the circulation path 210b into the compression chamber 236 via the inlet 238a of the compressor 230. The heat medium introduced into the compression chamber 236 is compressed by the compression operation of the piston 232, and then sent out from the outlet 238b to the circulation path 210c when the piston 232 is positioned near its top dead center.

As shown in FIG. 2, a storage space R for storing lubricating oil (for example, POE (polyol ester)) is formed inside the compressor 230, and the lubricating oil stored in the storage space R is The oil is supplied to the oil passage 312 of the drive shaft 234 by the lubricating oil pump 310. The lubricating oil supplied to the oil passage 312 passes through an oil passage (not shown) of the piston 232 and is supplied to the outer peripheral surface of the piston 232. Further, the lubricating oil accommodated in the accommodating space R is supplied to the connecting portion of the piston 232 and the drive shaft 234, the outer peripheral surface of the piston 232, and the inner peripheral surface of the compression chamber 236 (cylinder) by the spreading unit 320. In this way, the lubricating oil is supplied to the outer peripheral surface of the piston 232 and the inner peripheral surface of the compression chamber 236, so that the friction coefficient between the piston 232 and the compression chamber 236 is reduced, and the wear of the piston 232 and the compression chamber 236 is reduced. Reduced.

As described above, since the heat medium is introduced into the compression chamber 236 of the heat pump unit 200 and the lubricating oil is supplied to the inner peripheral surface of the compression chamber 236, the heat medium is dissolved in the lubricating oil in the compression chamber 236. There is a case. In this case, the lubricating oil circulates in the circulation path 210 in a state where the heat medium is dissolved, that is, the compression operation of the compressor 230 is continued in a state where the heat medium is dissolved in the lubricating oil.

As described above, when the operation of the heat pump unit 200 is stopped, if the driving of the compressor 230 is stopped without closing the expansion valve 260, there is a possibility that a liquid heat medium remains in the evaporator 220. In this state, when the operation of the heat pump unit 200 is started next, the liquid heat medium remaining in the evaporator 220 is introduced into the compressor 230 as it is, and the compressor 230 may cause a malfunction. On the other hand, when the heat pump unit 200 is stopped, if the expansion valve 260 is fully closed at a time while the compressor 230 is driven in order to avoid the liquid heat medium remaining in the evaporator 220, the compressor The pressure in the housing space R of 230 may drop rapidly, and the heat medium dissolved in the lubricating oil of the compressor 230 may foam and damage the compressor 230. For example, the heat medium bubbles may reach the compression chamber 236.

In particular, the heat medium used in the heat pump unit 200 of the vacuum cleaning apparatus 100 is lubricated more than the heat medium used in the heat pump unit of a refrigerator, a freezer, an air conditioner, a water heater, etc. (hereinafter referred to as “home appliance device”). It is easy to dissolve in oil. Specifically, in order for the vacuum cleaning apparatus 100 to generate the vapor of the hydrocarbon-based cleaning agent, it is necessary to heat the hydrocarbon-based cleaning agent to a high temperature such as about 80 ° C. to 140 ° C., for example. Therefore, the boiling point of the heat medium used for the heat pump unit 200 of the vacuum cleaning apparatus 100 is higher than that of the heat medium used for the home appliance or general industry heat pump unit. For example, the compressor inlet temperature of a heat medium used in a heat pump unit of a home appliance is about 30 ° C., the compressor outlet temperature is about 60 ° C., and the heat medium compressor used in a heat pump unit for general industry. The inlet temperature is about 90 ° C, and the compressor outlet temperature is about 110 ° C. On the other hand, the temperature of the inlet 238a (heat medium passing through the circulation path 210b) of the heat medium compressor 230 used in the heat pump unit 200 of the vacuum cleaning apparatus 100 is about 100 ° C. to 110 ° C. The temperature of the outlet 238b (heat medium passing through the circulation path 210c) is about 140 ° C.

Such a heat medium having a relatively high boiling point generally has a higher solubility in the lubricating oil of the compressor 230 constituting the heat pump unit 200 than a heat medium having a relatively low boiling point. More specifically, the heat medium used in the heat pump unit of the home appliance is only about a few percent dissolved in the lubricating oil of the compressor, but the heat medium used in the heat pump unit 200 of the vacuum cleaning device 100 is compressed. About 20% may be dissolved in the lubricating oil of the machine 230. Therefore, in the compressor 230 of the heat pump unit 200 of the vacuum cleaning device 100, foaming of the heat medium becomes more conspicuous than the compressor of the heat pump unit of the household electrical appliance, and the compressor 230 is damaged due to a decrease in the liquid level LH of the lubricating oil. Is likely. Since foaming of the heat medium is caused by vaporization of the liquid heat medium, when the heat medium in the lubricating oil is vaporized, the liquid level LH of the lubricating oil is lowered. When the liquid level LH decreases and the amount of lubricating oil necessary for lubrication between the connecting portion of the piston 232 and the drive shaft 234 and between the outer peripheral surface of the piston 232 and the inner peripheral surface of the compression chamber 236 cannot be secured, The wear of the compressor is accelerated, and the compressor 230 may be damaged.

Therefore, when the compressor 230 is stopped, the control unit 280 adjusts the opening degree of the expansion valve 260 to suppress foaming of the heat medium in the accommodation space R of the compressor 230. Hereinafter, stop control of the compressor 230 by the control unit 280 will be described.

(Stop control of compressor 230)
When the control unit 280 receives an instruction to stop the heat pump unit 200, that is, an instruction to stop the compression operation of the heat medium by the compressor 230, the control unit 280 receives the lubricant oil stored in the storage space R of the compressor 230. The opening degree of the expansion valve 260 is reduced so that the height of the liquid level LH does not become less than a threshold value preset in the compressor 230. In other words, the control unit 280 opens the opening of the expansion valve 260 so that the height of the liquid level LH of the lubricating oil stored in the storage space R maintains a value equal to or higher than a threshold value set in advance in the compressor 230. Keep it small. The threshold value preset in the compressor 230 is the height of the level of the lubricating oil required for lubrication between the connecting portion of the piston 232 and the drive shaft 234 and between the outer peripheral surface of the piston 232 and the inner peripheral surface of the compression chamber 236. Is the lower limit of. For this reason, the appropriate lubrication with respect to the structural member of the compressor 230 can be maintained by maintaining the height of the liquid level LH of the lubricating oil at a value equal to or higher than the threshold value. Note that an instruction to stop the heat pump unit 200 may be input to the control unit 280 by an operator via an input device or the like, or may be received from another control device or the like.

The control unit 280 reduces the opening of the expansion valve 260 so that the height of the liquid level LH of the lubricating oil stored in the storage space R of the compressor 230 does not become less than a threshold value preset in the compressor 230. For example, the following four means may be mentioned.

(Opening adjustment 1 of the expansion valve 260 by the controller 280)
The control unit 280 reduces the opening degree of the expansion valve 260 so that the change rate of the opening degree of the expansion valve 260 is maintained at a predetermined first value, so that the lubrication accommodated in the accommodation space R is maintained. The height of the oil level LH should not be less than the threshold value. When the opening when the expansion valve 260 is fully open is 100%, the first value is, for example, 3% / min.

(Opening adjustment 2 of the expansion valve 260 by the control unit 280)
The control unit 280 reduces the opening of the expansion valve 260 so that the pressure decrease rate of the storage space R measured by the pressure measurement unit 270 is maintained at a predetermined second value. The height of the liquid level LH of the lubricating oil accommodated in the space R is prevented from becoming less than the threshold value. The second value is, for example, a decreasing rate of (10% of the pressure during normal operation of the compressor 230) / min or less. Therefore, when the pressure during normal operation of the compressor 230 is, for example, 500 kPa, the second value is 50 kPa / min.

(Opening adjustment 3 of the expansion valve 260 by the control unit 280)
The compressor 230 is provided with a liquid level gauge, and the control unit 280 is configured such that the height of the liquid level LH of the lubricating oil stored in the storage space R of the compressor 230 is less than a threshold set in the compressor 230 in advance. In order to prevent this, the opening of the expansion valve 260 is reduced. For the liquid level meter, for example, an existing technology such as an optical sensor or an image processing apparatus can be used.

(Opening adjustment 4 of the expansion valve 260 by the control unit 280)
The compressor 230 is equipped with a device for measuring the amount of bubbles (the amount of bubbles due to foaming of the heat medium), and the control unit 280 determines that the amount of bubbles generated in the storage space R of the compressor 230 is greater than or equal to a predetermined amount. In order to avoid this, the opening degree of the expansion valve 260 is reduced. The predetermined amount is the upper limit of the amount of bubbles that can maintain the lubrication (lubrication using the lubricating oil) between the connecting portion of the piston 232 and the drive shaft 234 and between the outer peripheral surface of the piston 232 and the inner peripheral surface of the compression chamber 236. Value. As an apparatus for measuring the amount of bubbles, for example, an existing technique such as a void ratio meter, an optical sensor, an image processing apparatus, or the like can be used.

Based on the values described in the opening degree adjustments 1 to 4 described above, by reducing the opening degree of the expansion valve 260, the height of the liquid level LH of the lubricating oil housed in the housing space R of the compressor 230 is reduced. It is possible to prevent the compressor 230 from becoming less than a preset threshold value. In addition, since the liquid level LH of lubricating oil will fall if the foaming amount (vaporization amount) of a heat medium increases as mentioned above, there exists a correlation between both. For this reason, by maintaining the height of the liquid level LH of the lubricating oil stored in the storage space R at a value equal to or higher than a preset threshold value, the amount of foaming of the heat medium (the amount of foaming per unit time) is increased. It can be suppressed to a certain value or less, and therefore, rapid foaming of the heat medium can be prevented.

Therefore, before the driving of the compressor 230 is stopped, the pressure in the accommodation space R can be gradually lowered, and foaming of the heat medium dissolved in the lubricating oil can be suppressed. Therefore, a situation in which the apparent viscosity of the lubricating oil is reduced can be avoided, and a sufficient oil film of the lubricating oil can be formed on the sliding members such as the piston 232, the drive shaft 234, and the compression chamber 236. As a result, it is possible to avoid a situation in which the sliding member is worn and the compressor 230 is damaged.

The control unit 280 fully closes the expansion valve 260 to block the flow of the heat medium into the compressor 230 through the expansion valve 260, and then the pressure in the accommodation space R measured by the pressure measurement unit 270 is in the lubricating oil. The compression operation of the heat medium by the compressor 230 is maintained until the pressure becomes lower than a pressure corresponding to a predetermined concentration of the heat medium contained (hereinafter referred to as “equivalent pressure”). The equivalent pressure is, for example, 40 kPa (Abs).

Thus, since the control unit 280 stops the driving of the compressor 230 after the expansion valve 260 is fully closed, it is possible to prevent the liquid heat medium from remaining in the evaporator 220. As a result, when the control unit 280 starts to operate the heat pump unit 200 next time, the liquid heat medium is not introduced into the compressor 230, so that the compressor 230 can be prevented from being damaged.

In addition, after the expansion valve 260 is fully closed, the control unit 280 maintains (continues) the compression operation of the heat medium by the compressor 230 until the pressure in the accommodation space R measured by the pressure measurement unit 270 becomes less than the equivalent pressure. By doing so, the heat medium dissolved in the lubricating oil can be vaporized. Therefore, the heat medium can be removed from the lubricating oil, and the foaming of the heat medium in the lubricating oil, that is, the decrease in the liquid level LH of the lubricating oil is suppressed when the operation of the heat pump unit 200 is started next. Is possible.

(Operation method of heat pump unit 200)
Subsequently, an operation method of the heat pump unit 200, in particular, a stop method will be described. FIG. 3 is a flowchart for explaining the processing flow of the operation method of the heat pump unit 200. The stop control of the heat pump unit 200 is a process performed when the heat pump unit 200 is in operation.

When control unit 280 receives an instruction to stop the compression operation of the heat medium by compressor 230 in response to an operation input by the operator (YES in step S410), control unit 280 is accommodated in accommodation space R of compressor 230. The opening degree of the expansion valve 260 is decreased so that the height of the liquid level LH of the lubricating oil does not become less than the threshold value A preset in the compressor 230 (step S412).

Subsequently, the control unit 280 determines whether or not the expansion valve 260 is fully closed (step S414). If the expansion valve 260 is not fully closed (NO in step S414), the process of step S412 is continued. Step S414 is executed again.

On the other hand, when expansion valve 260 is fully closed (YES in step S414), control unit 280 determines whether or not the pressure in housing space R of compressor 230 measured by pressure measurement unit 270 is less than the equivalent pressure. Is determined (step S416). When the pressure in the accommodation space R is not less than the equivalent pressure (NO in step S416), the control unit 280 maintains the drive of the compressor 230 and executes step 416 again. When the pressure in the accommodation space R becomes less than the equivalent pressure (YES in step S416), the control unit 280 stops driving the compressor 230 (step S418).

As described above, according to the heat pump unit 200 and the operation method of the heat pump unit 200 according to the present embodiment, foaming of the heat medium contained in the lubricating oil can be suppressed when the compressor 230 is stopped. It becomes possible to prevent the compressor 230 from being damaged.

The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such embodiments. Those skilled in the art will be able to conceive various changes and modifications within the scope of the claims, and these naturally belong to the technical scope of the present invention.

For example, in the above-described embodiment, the heat pump unit 200 constituting the vacuum cleaning apparatus 100 has been described as an example, but the apparatus on which the heat pump unit 200 is mounted is not limited. For example, even in a heat pump unit mounted on various electric devices such as a refrigerator, a freezer, an air conditioner, and a water heater, the heat medium may be dissolved in the lubricating oil of the compressor. Therefore, the operation method of the heat pump unit 200 and the heat pump unit 200 according to the present invention can be applied to the above-described electric devices and the like.

Further, in the above-described embodiment, the control unit 280 fully closes the expansion valve 260 and then the heat medium generated by the compressor 230 until the pressure in the accommodation space R measured by the pressure measurement unit 270 becomes less than the equivalent pressure. The configuration for maintaining the compression operation has been described. However, the compression operation of the heat medium by the compressor 230 may be maintained for a time expected to be less than the corresponding pressure after the expansion valve 260 is fully closed. This time may be set in advance by experiments or the like.

In the above-described embodiment, the configuration in which the heat pump unit 200 includes the intermediate heat exchanger 250 has been described, but the intermediate heat exchanger 250 may not be provided. Even when the intermediate heat exchanger 250 is not provided, when the compressor 230 is stopped, foaming of the heat medium contained in the lubricating oil can be suppressed, and damage to the compressor 230 can be prevented. .

In the above-described embodiment, the vacuum cleaning apparatus 100 in which the cleaning with the condensed cleaning agent supplied from the shower unit 110 and the cleaning with the steam supplied from the steam supply unit 130 are performed in the cleaning chamber 102 has been described. However, for example, an immersion chamber may be provided in the vacuum container 104 below the cleaning chamber 102, and the workpiece W may be cleaned by immersing the workpiece W in the immersion chamber.

Specifically, in the immersion chamber, an amount of hydrocarbon-based cleaning agent (liquid) that can completely immerse the workpiece W is stored, and a heater for heating the hydrocarbon-based cleaning agent is provided. ing. Further, an intermediate door is provided between the cleaning chamber 102 and the immersion chamber, and the intermediate door is configured so that the cleaning chamber 102 and the immersion chamber communicate with each other or the communication is blocked. Yes. Note that the hydrocarbon-based cleaning agent stored in the immersion chamber includes the condensed cleaning agent supplied from the shower unit 110 and the condensed cleaning agent supplied from the cleaning agent storage unit 124 via the condensed cleaning agent supply pipe 126. Either one or both. Further, in this case, an elevating device is provided in the placement unit 108, and the placement unit 108 is configured to be movable in the vertical direction. Therefore, the workpiece W is moved from the cleaning chamber 102 to the immersion chamber by driving the lifting device in a state where the intermediate door is opened and the cleaning chamber 102 and the immersion chamber are communicated, or the workpiece W is moved to the immersion chamber. The workpiece W is cleaned by moving it to the cleaning chamber 102.

In addition, each process of the operating method of the heat pump unit of this specification does not necessarily need to process in time series along the order described as a flowchart, and may include the process by parallel or a subroutine.

The present invention can be used for the heat pump unit and the operation method of the heat pump unit.

200 heat pump unit 210 circulation path 220 evaporator 230 compressor 232 piston (compression mechanism)
234 Drive shaft (compression mechanism)
240 Condenser 260 Expansion Valve 270 Pressure Measurement Unit 280 Control Unit R Storage Space

Claims (7)

A circulation path through which the heat medium circulates;
A compressor having a compression mechanism and a storage space for storing lubricating oil supplied to the compression mechanism, and adiabatically compressing and heating the heat medium circulating in the circulation path;
A condenser that is provided downstream of the compressor in the circulation path and that condenses the heat medium by cooling the heat medium heated by the compressor;
An expansion valve that is provided downstream of the condenser in the circulation path and cools the heat medium condensed by the condenser by decompressing and expanding;
An evaporator provided downstream of the expansion valve in the circulation path and evaporating the heat medium by heating the heat medium cooled by the expansion valve;
A controller that controls the drive of the compressor and the opening of the expansion valve to control the circulation amount of the heat medium in the circulation path;
With
When the control unit receives an instruction to stop the compression operation of the heat medium by the compressor,
The opening of the expansion valve is reduced so that the level of the lubricating oil stored in the storage space maintains a value equal to or higher than a threshold value preset in the compressor,
A heat pump unit configured to stop the compression operation of the heat medium by the compressor after the expansion valve is fully closed to block the flow of the heat medium to the compressor through the expansion valve. The control unit reduces the opening of the expansion valve so that the rate of change of the opening of the expansion valve is maintained at a predetermined first value, so that the lubricating oil stored in the storage space The heat pump unit according to claim 1, wherein the liquid level is maintained at a value equal to or higher than the threshold value. The control unit reduces the opening of the expansion valve so that the rate of decrease in the pressure of the storage space is maintained at a predetermined second value, so that the lubricating oil stored in the storage space is reduced. The heat pump unit according to claim 1, which is configured to maintain the height of the liquid level at a value equal to or higher than the threshold value. The control unit, after fully closing the expansion valve, until the pressure in the accommodation space becomes less than a pressure corresponding to a predetermined concentration of the heat medium contained in the lubricating oil. When the compression operation of the heat medium is continued, and the pressure in the housing space becomes less than a pressure corresponding to a predetermined concentration of the heat medium contained in the lubricating oil, the compression operation of the heat medium by the compressor is performed. The heat pump unit according to claim 1, wherein the heat pump unit is configured to stop. The control unit, after fully closing the expansion valve, until the pressure in the accommodation space becomes less than a pressure corresponding to a predetermined concentration of the heat medium contained in the lubricating oil. When the compression operation of the heat medium is continued, and the pressure in the housing space becomes less than a pressure corresponding to a predetermined concentration of the heat medium contained in the lubricating oil, the compression operation of the heat medium by the compressor is performed. The heat pump unit according to claim 2, wherein the heat pump unit is configured to stop. The control unit, after fully closing the expansion valve, until the pressure in the accommodation space becomes less than a pressure corresponding to a predetermined concentration of the heat medium contained in the lubricating oil. When the compression operation of the heat medium is continued, and the pressure in the housing space becomes less than a pressure corresponding to a predetermined concentration of the heat medium contained in the lubricating oil, the compression operation of the heat medium by the compressor is performed. The heat pump unit according to claim 3, wherein the heat pump unit is configured to stop. A circulation path through which the heat medium circulates;
A compressor having a compression mechanism and a storage space for storing lubricating oil supplied to the compression mechanism, and adiabatically compressing and heating the heat medium circulating in the circulation path;
A condenser that is provided downstream of the compressor in the circulation path and that condenses the heat medium by cooling the heat medium heated by the compressor;
An expansion valve that is provided downstream of the condenser in the circulation path and cools the heat medium condensed by the condenser by decompressing and expanding;
An evaporator provided downstream of the expansion valve in the circulation path and evaporating the heat medium by heating the heat medium cooled by the expansion valve;
A method of operating a heat pump unit comprising
When receiving an instruction to stop the compression operation of the heat medium by the compressor,
The opening of the expansion valve is reduced so that the level of the lubricating oil stored in the storage space maintains a value equal to or higher than a threshold value preset in the compressor,
A method of operating a heat pump unit, wherein the expansion valve is fully closed and the flow of the heat medium into the compressor through the expansion valve is shut off, and then the compression operation of the heat medium by the compressor is stopped.

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