JP4599190B2 - Flow rate adjusting device and air conditioner - Google Patents

Description

  The present invention relates to returning lubricating oil separated from a refrigerant to a compressor included in an air conditioner.

  An air conditioner is widely used to appropriately adjust the temperature and humidity of air in a house, a building, and other internal spaces. From the compressor provided in the air conditioner, lubricating oil for lubricating the compressor flows into the interior of each device such as a pipe of an air conditioner and a condenser together with the refrigerant. For this reason, the refrigerant | coolant discharged from the compressor is guide | induced to an oil separator, and lubricating oil is isolate | separated from a refrigerant | coolant here. Then, the separated lubricating oil is returned to the compressor. In Patent Document 1, in order to make the temperature of the lubricating oil appropriate, the compressor is based on the pressure difference between the refrigerant pressure at the compressor outlet and the refrigerant pressure at the compressor inlet and the lubricating oil temperature. A technique for controlling the flow rate of the lubricating oil to be returned to is disclosed.

JP-A-6-74579

  However, the technique disclosed in Patent Document 1 can appropriately maintain the temperature of the lubricating oil, but does not consider the amount of lubricating oil discharged from the compressor together with the refrigerant. As a result, when the operating state of the compressor changes, the amount of lubricating oil returned to the compressor becomes excessive or excessive.

  This invention is made in view of the above, Comprising: The flow regulating device and air conditioner which can return the suitable quantity of lubricating oil according to the driving | running state of the compressor with which an air conditioner is equipped to a compressor The purpose is to provide.

To solve the above problems and achieve the object, flow control device according to the present invention separates the compressors, the lubricating oil contained in the refrigerant discharged is compressed by the compressor from the refrigerant It is disposed between the oil separator, according to the refrigerant circulation amount parameter regarding circulation amount of the refrigerant discharged from the compressor increases, increasing the flow rate of lubricating oil returning from the oil separator to the compressor a that flow amount adjusting device, and the pressure of the refrigerant at the outlet of the compressor, based on the differential pressure parameter related to the pressure difference between the pressure of the refrigerant at the inlet of the compressor, to the compressor from the oil separator The flow rate of the lubricating oil to be returned is kept constant, and the differential pressure parameter is determined by a difference between a refrigerant pressure at the outlet of the compressor and a refrigerant pressure at the inlet of the compressor, Oil separation Characterized Sekidea Rukoto of the reciprocal of the viscosity of the lubricating oil returned to the compressor from.

This flow rate adjusting device is applied to an air conditioner, and adjusts the flow rate of lubricating oil separated from the refrigerant by an oil separator and returned to the compressor. The flow rate adjusting device increases the flow rate of the lubricating oil returned from the oil separator to the compressor as the refrigerant circulation amount parameter related to the circulation amount of the refrigerant discharged from the compressor increases. Accordingly, in consideration of the amount of lubricating oil discharged from the compressor together with the refrigerant, an appropriate amount of lubricating oil corresponding to the operating state of the compressor can be returned to the compressor. Further, the flow rate adjusting device operates so as to keep the flow rate of the lubricating oil returned from the oil separator to the compressor based on the differential pressure parameter. As a result, when the differential pressure between the refrigerant pressure at the compressor outlet and the refrigerant pressure at the compressor inlet is small, the amount of oil returned to the compressor is ensured to suppress insufficient lubrication. it can. And when the said differential pressure | voltage is large, it can suppress that an excess oil returns to a compressor, and can reduce a possibility that oil compression will generate | occur | produce. Further, the differential pressure parameter includes a high / low differential pressure obtained by a difference between a refrigerant pressure at the outlet of the compressor and a refrigerant pressure at the inlet of the compressor, and lubrication returned from the oil separator to the compressor. The product is preferably the product of the reciprocal of the viscosity of the oil. Thus, by considering the viscosity μ of the oil, a more preferable oil return flow rate can be set for the operating state of the compressor.

  Here, it is preferable that the refrigerant circulation amount parameter is a product of the number of rotations of the compressor and the pressure of the refrigerant at the inlet of the compressor. As described above, if the refrigerant circulation amount parameter includes the rotation speed of the compressor and the pressure at the inlet of the compressor, the operation state of the compressor is considered in consideration of the rotation speed of the compressor and the density of the refrigerant. A more suitable amount of lubricating oil can be returned.

  The flow regulating device according to the present invention is the flow regulating device according to the present invention, comprising a plurality of fluid throttle means and a plurality of flow path opening / closing means, wherein the fluid throttle means are connected in parallel to each other, and The path opening / closing means is connected in series to each of the fluid throttle means.

  Since the flow rate adjusting device includes the configuration of the flow rate adjusting device, the same operation and effect as the flow rate adjusting device are achieved. Further, the flow rate adjusting device includes fluid throttle means connected in parallel and flow path opening / closing means arranged in series with each fluid throttle means. Accordingly, the flow rate adjusting device can be configured with a relatively simple configuration. Further, by providing a plurality of fluid throttle means in parallel, a fluid throttle means having a fixed opening (for example, a capillary) can be used. As a result, since it is not necessary to use a fluid throttle means with a variable opening, the cost of the flow rate adjusting device can be reduced.

  The flow rate adjusting device according to the present invention is characterized in that, in the flow rate adjusting device, when the operation of the compressor is in a transient state, the flow rate of lubricating oil returned from the oil separator to the compressor is maximized. And

  Since the flow rate adjusting device includes the configuration of the flow rate adjusting device, the same operation and effect as the flow rate adjusting device are achieved. Further, the flow rate adjusting device is returned to the compressor at the time of transition such as when the compressor is started or when the rotation speed of the compressor is rapidly increased to rapidly increase the refrigerant circulation amount. Set the lubricating oil flow rate to the maximum. As a result, a sufficient amount of lubricating oil is returned to the compressor, and insufficient lubrication of the compressor during the transition can be avoided.

  The flow rate adjusting device according to the present invention is characterized in that, in the flow rate adjusting device, when the compressor stops, the flow rate of lubricating oil returned from the oil separator to the compressor is set to zero. .

  Since the flow rate adjusting device includes the configuration of the flow rate adjusting device, the same operation and effect as the flow rate adjusting device are achieved. Further, the flow rate adjusting device sets the flow rate of the lubricating oil returned from the oil separator to the compressor to 0 when the compressor stops. Thereby, after the compressor is stopped, the amount of lubricating oil in the compressor can be prevented from increasing more than necessary, so that it is possible to suppress a decrease in the durability of the compressor due to oil compression.

  The flow rate adjusting device according to the next aspect of the present invention is the flow rate adjusting device, wherein the flow rate is changed when the flow rate of the lubricating oil returned from the oil separator to the compressor is increased; When the flow rate of the lubricating oil returned to the machine is decreased, the timing for changing the flow rate is different.

  Since the flow rate adjusting device includes the configuration of the flow rate adjusting device, the same operation and effect as the flow rate adjusting device are achieved. Further, the flow rate adjusting device varies the way of changing the flow rate of the lubricating oil returned from the oil separator to the compressor depending on the path of the change. Thereby, since it is possible to suppress the frequent switching operation of the flow rate, it is possible to suppress a decrease in durability of the flow rate adjustment device.

  The air conditioner according to the present invention includes a compressor that compresses and discharges a refrigerant, an oil separator that separates lubricating oil contained in the refrigerant discharged from the compressor from the refrigerant, and the flow rate adjusting device. A condenser that condenses and liquefies the refrigerant discharged from the compressor, an expansion valve that decompresses and expands the refrigerant liquefied by the condenser to form a low-temperature and low-pressure liquid refrigerant, and a low temperature that passes through the expansion valve And an evaporator for exchanging heat between the low-pressure liquid refrigerant and the air.

  Since this air conditioner adjusts the amount of lubricating oil returned to the compressor by the flow rate adjusting device, it is possible to return an appropriate amount of lubricating oil to the compressor according to the operating state of the compressor included in the air conditioning device. it can.

  The flow control device and the air conditioner according to the present invention can return an appropriate amount of lubricating oil to the compressor according to the operating state of the compressor included in the air conditioner.

  Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to the best mode for carrying out the invention. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or that are substantially the same. In the following, a so-called multi-type air conditioner that drives a plurality of indoor units will be described as an example, but the application target of the present invention is not limited thereto.

  The flow rate adjusting device according to this embodiment is disposed between the compressor and the oil separator, and serves as a refrigerant circulation amount parameter relating to the circulation amount of the refrigerant discharged from the compressor, and the refrigerant parameter increases. Therefore, it is characterized in that the flow rate of the lubricating oil returned from the oil separator to the compressor is increased.

  Here, the flow rate of the lubricating oil refers to the amount of lubricating oil that returns to the compressor per unit time, or the amount of lubricating oil that returns to the compressor within a predetermined time. When the lubricant flows continuously, the amount of lubricant that returns to the compressor depends on the amount of lubricant that returns to the compressor per unit time, even if the amount of lubricant returns to the compressor within a predetermined time. You may compare by the quantity. On the other hand, when the average amount of lubricating oil returning to the compressor within a predetermined time is changed by changing the valve opening time within a predetermined time using, for example, an on-off valve, the flow of the lubricating oil is intermittent. Become. In such a case, the amount of lubricant returning to the compressor is compared by the amount of lubricant returning to the compressor within a predetermined time, rather than by the amount of lubricant returning to the compressor per unit time. It is better to do.

FIG. 1 is a conceptual diagram showing a configuration of an air conditioner according to this embodiment. FIG. 1 shows a refrigerant circuit of an air conditioner (hereinafter referred to as air conditioner) 1 according to this embodiment. The air conditioner 1 is a so-called multi-type air conditioner including an outdoor unit 3 and a plurality of indoor units 2 ₁ and 2 ₂ to which a refrigerant is supplied from the outdoor unit 3. The air conditioner 1 includes two indoor units 2 ₁ and 2 ₂ , but the number of indoor units is not limited to two. Each of the indoor units 2 ₁ and 2 ₂ and the outdoor unit 3 are connected to each other through operation valves 49 ₁ and 49 ₂ provided in the outdoor unit 3. The operation valves 49 ₁ and 49 ₂ are fixed fully open after the indoor units 2 ₁ and 2 ₂ and the outdoor unit 3 are connected.

Each indoor unit 2 ₁ , 2 ₂ is provided with an indoor unit heat exchanger (condenser or evaporator) 2H ₁ , 2H ₂ , and a cooling electromagnetic expansion valve (expansion valve) 35 ₁ , 35 _2. Yes. The opening degree of the electromagnetic expansion valves 35 ₁ and 35 ₂ for cooling is adjusted according to the operating conditions of the indoor units 2 ₁ and 2 ₂ . For example, when the indoor units 2 ₁ and 2 ₂ are in cooling operation, the opening degree of the electromagnetic expansion valves 35 ₁ and 35 ₂ for cooling is adjusted for cooling. In the indoor unit heat exchangers 2H ₁ and 2H ₂ , the refrigerant sent from the outdoor unit 3 and the indoor air in which the indoor units 2 ₁ and 2 ₂ are installed exchange heat, and the temperature of the indoor air And adjust the humidity.

The outdoor unit 3 includes a compressor 30, an outdoor unit heat exchanger (condenser or evaporator) 32, a four-way valve 33, an accumulator 36, an oil separator 37, and a heating electromagnetic expansion valve (expansion valve). 38. Although the outdoor unit 3 of the air conditioner 1 according to this embodiment includes one compressor 30, the number of the compressors 30 included in the outdoor unit is not limited, and the outdoor unit 3 includes a plurality of compressors. A machine 30 may be provided. The refrigerant circulates in each component. The opening degree of the heating electromagnetic expansion valve 38 is adjusted according to the operating conditions of the indoor units 2 ₁ and 2 ₂ . For example, when heating each indoor unit 2 ₁ , 2 ₂ , the opening degree of the heating electromagnetic expansion valve 38 is adjusted for heating.

The compressor 30 compresses the refrigerant vapor sent via the accumulator 36 from the indoor unit heat exchangers 2H ₁ , 2H ₂ or the outdoor unit heat exchanger 32, and the pressure and temperature of the refrigerant vapor are reduced. Raise. The refrigerant discharged from the outlet (hereinafter referred to as compressor outlet) 30o of the compressor 30 is sent to the four-way valve 33 after the compressor lubricating oil (hereinafter referred to as oil) is separated by the oil separator 37, and from here to the outdoor It is sent to the machine heat exchanger 32 or the indoor unit heat exchangers 2H ₁ and 2H ₂ .

  The compressor 30 is driven by a gas engine 31 which is compressor driving means. The compressor driving means is not limited to the gas engine 31. The compressor 30 may be of a compressor driving means integrated type having a compressor driving means inside. The rotational speed (hereinafter referred to as compressor rotational speed) Nc of the compressor 30 is detected by a rotational speed sensor 42 which is a compressor rotational speed detection means. Here, as the rotation speed sensor 42, for example, an optical sensor can be used.

  In the vicinity of the compressor outlet 30o of the compressor 30, a compressor outlet pressure sensor 43, which is a compressor outlet pressure detecting means for detecting a refrigerant pressure (hereinafter referred to as compressor outlet pressure) Po at the outlet of the compressor, is provided. ing. The compressor outlet pressure sensor 43 only needs to be able to detect the pressure of the refrigerant at the compressor outlet 30o of the compressor 30. If this purpose can be achieved, the installation location of the compressor outlet pressure sensor 43 is not limited.

  The inlet (hereinafter referred to as accumulator inlet) 36i of the accumulator 36 is provided with a compressor inlet pressure sensor 41 which is a compressor inlet pressure detecting means for detecting a refrigerant pressure (hereinafter referred to as compressor inlet pressure) Pi at the outlet of the compressor. It has been. The compressor inlet pressure sensor 41 only needs to be able to detect the refrigerant pressure at the inlet (hereinafter referred to as compressor inlet) 30i of the compressor 30. Therefore, as long as this purpose can be achieved, the installation location of the compressor inlet pressure sensor 41 does not matter. .

  The refrigerant discharged from the compressor 30 is introduced into the oil separator 37. Then, the oil contained in the refrigerant is separated in the oil separator 37. The oil separated from the refrigerant is once stored in the oil separator 37 and then returned to the compressor 30. Here, the temperature of the oil returned to the compressor 30 is detected by an oil temperature sensor 44 that is an oil temperature detecting means. Returning the oil separated from the refrigerant to the compressor 30 in this way is called oil return. In returning oil, the flow rate adjusting device 50 adjusts the flow rate of oil returned from the oil separator 37 to the compressor 30 (hereinafter referred to as oil return flow rate). The operation of the flow control device 50 is controlled by the flow control device 20. The flow rate adjusting means according to this embodiment includes a flow rate adjusting device 50 and a flow rate control device 20. The configurations of the flow rate adjusting device 50 and the flow rate control device 20 will be described later.

The air conditioner 1 can cause the indoor units 2 ₁ and 2 ₂ to perform cooling or heating operation by switching the four-way valve 33 of the outdoor unit 3. When each of the indoor units 2 ₁ and 2 ₂ is in a cooling operation, the refrigerant is circulated in the direction indicated by the solid line arrow in FIG. At this time, in principle, the opening degree of the heating electromagnetic expansion valve 38 is fully opened, and the opening degree of the cooling electromagnetic expansion valves 35 ₁ , 35 ₂ is adjusted for cooling.

At this time, the outdoor unit heat exchanger 32 functions as a condenser that condenses and liquefies the refrigerant discharged from the compressor. The cooling electromagnetic expansion valves 35 ₁ and 35 ₂ function as expansion valves that depressurize and expand the refrigerant liquefied by the outdoor unit heat exchanger 32 that functions as a condenser. Each indoor heat exchanger 2H _1, 2H ₂ functions between the refrigerant and air passing through the cooling solenoid expansion valve 35 _1, 35 ₂ which functions as an expansion valve as evaporator for heat exchange.

During the cooling operation of each indoor unit 2 ₁ , 2 ₂ , refrigerant vapor generated by absorbing the heat of the indoor air in each indoor unit heat exchanger 2 H ₁ , 2 H ₂ is introduced into the compressor 30. And compressed here. The refrigerant whose pressure and temperature have risen is sent to the outdoor unit heat exchanger 32. The refrigerant vapor sent to the outdoor unit heat exchanger 32 is condensed and liquefied by discarding heat to the outside in the outdoor unit heat exchanger 32. This liquid refrigerant is temporarily stored in the receiver 34.

The liquid refrigerant sent from the receiver 34 to the indoor unit heat exchangers 2H ₁ and 2H ₂ is reduced in pressure by the cooling electromagnetic expansion valves 35 ₁ and 35 ₂ provided in the indoor unit heat exchangers 2H ₁ and 2H _2. A part of the expanded and liquefied refrigerant evaporates to become wet steam. The wet steam is further evaporated to dry steam while taking heat with the indoor unit heat exchangers 2H ₁ and 2H ₂ . The refrigerant in the dry vapor state returns to the outdoor unit 3 side and enters the accumulator 36 through the four-way valve 33. The accumulator 36 removes the liquid refrigerant from the refrigerant and sends the refrigerant in the gas state to the compressor 30.

Since the wet steam refrigerant takes heat at the indoor heat exchanger 2H _1, 2H _2, the temperature of the indoor unit heat exchanger 2H _1, 2H ₂ is lower than the ambient temperature. To the indoor units heat exchanger 2H _1, 2H ₂ by blowing air, by heat exchange between the indoor heat exchanger 2H _1, 2H ₂ and the air, the air temperature was lowered Send it indoors. Thereby, each room can be cooled by each indoor unit 2 ₁ , 2 ₂ installed in each room.

When each indoor unit 2 ₁ , 2 ₂ is operated for heating, the refrigerant is circulated in the direction indicated by the dashed arrow in FIG. At this time, the opening degree of the cooling electromagnetic expansion valves 35 ₁ and 35 ₂ is changed from that for cooling operation to that for heating operation, and the opening degree of the heating electromagnetic expansion valve 38 is adjusted for heating. At this time, the outdoor unit heat exchanger 32 functions as an evaporator that exchanges heat between the refrigerant and the air that have passed through the heating electromagnetic expansion valve 38 that functions as an expansion valve. Each indoor unit heat exchanger 2H ₁ , 2H ₂ functions as a condenser that condenses and liquefies the refrigerant discharged from the compressor 30. The heating electromagnetic expansion valve 38 functions as an expansion valve that decompresses and expands the refrigerant liquefied by the indoor unit heat exchangers 2H ₁ and 2H ₂ functioning as a condenser.

During the heating operation of each indoor unit 2 ₁ , 2 ₂ , the four-way valve 33 is switched to the heating operation. At this time, refrigerant vapor generated by absorbing the heat of the outside air by the outdoor unit heat exchanger 32 is introduced into the compressor 30 and compressed therein. The refrigerant and the pressure and temperature rises is sent to the indoor heat exchanger unit 2H _1, 2H _2. The refrigerant vapor sent to each indoor unit heat exchanger 2H ₁ , 2H ₂ is liquefied by applying heat to the indoor air. The liquefied refrigerant is squeezed and expanded by the heating electromagnetic expansion valve 38, and a part of the liquefied refrigerant is evaporated to become wet steam. The wet steam is sent to the outdoor unit heat exchanger 32, and further evaporates into dry steam while taking heat from the outside air.

The refrigerant vapor sent to each indoor unit heat exchanger 2H ₁ , 2H ₂ heats indoor air and liquefies, and therefore has a higher temperature than indoor air. Heat exchanger for the indoor unit to 2H _1, 2H ₂ by blowing air, by heat exchange between the indoor heat exchanger 2H _1, 2H ₂ and the air, the air temperature was increased Send to each room. Thereby, each room can be heated by each indoor unit 2 ₁ , 2 ₂ installed in each room. Next, the configuration of the flow rate adjusting device 50 will be described.

FIG. 2A is an explanatory diagram of a flow rate adjusting device according to this embodiment. 2-1 connects a plurality of capillaries (fluid throttling means) 51 ₁ , 51 ₂ ... 51 _n having different throttling amounts in parallel with each other. Moreover, the on-off valve 52 ₁ is a flow path opening and closing means, 52 ₂ · · · 52 _n is connected to each of the capillaries 51 _1, 51 ₂ ··· 51 _n series. In this embodiment, each of the capillary 51 _1, 51 oil separator 37 side of the ₂ · · · 51 _n, off valves 52 _1, 52 ₂ ··· 52 _n are connected. Then, the flow rate adjusting device 50 selects the capillary through which oil flows from the oil separator 37 to the compressor 30 by switching the opening and closing of the on-off valves 52 ₁ , 52 ₂ ... 52 _n and adjusts the oil return flow rate. . Incidentally, the opening and closing valve 52 _1, 52 ₂ ··· 52 _n may be connected to each of the capillary 51 _1, 51 compressor 30 side of the ₂ · · · 51 _n.

The opening / closing of the on-off valves 52 ₁ , 52 ₂ ... 52 _n is controlled by the flow control device 20 (FIG. 1). In adjusting the oil return flow rate, a single capillary (for example, capillary 51 ₁ ) may be selected, or a plurality of capillaries may be selected in combination (for example, capillary 51 ₁ and capillary 51 ₂ ). Further, the oil return flow rate may be adjusted by adjusting the opening time of the on-off valve within a predetermined time.

  Here, it is preferable that the oil returned to the compressor 30 removes the dust in the oil by the dust removing means provided closer to the oil separator 37 than the compressor inlet 30i. In this embodiment, a strainer 54 as a dust removing means is provided between the flow rate adjusting device 50 and the oil separator 37. Accordingly, inflow of dust into the compressor 30 can be suppressed, and inflow of dust into the capillary and the on-off valve can be suppressed, so that the possibility of the capillary and the on-off valve being blocked can be extremely reduced.

  FIG. 2B is an explanatory diagram of another configuration example of the flow rate adjusting device according to this embodiment. The flow rate adjusting device 50 a is configured by a flow rate adjusting valve 53. That is, the flow rate adjustment valve 53 is provided between the oil separator 37 and the compressor 30, and the opening degree of the flow rate adjustment valve 53 is adjusted by the flow rate control device 20, thereby adjusting the oil return flow rate to the compressor 30. . A strainer 54 is provided between the flow regulating valve 53 and the oil separator 37 for the above reason. Here, an oil return flow rate to the compressor 30 may be adjusted by providing an opening / closing valve instead of the flow rate adjustment valve 53 and changing the valve opening time within a predetermined time. Next, the flow control device 20 according to this embodiment will be described.

  FIG. 3 is an explanatory diagram showing the configuration of the flow control device according to this embodiment. In the air conditioner 1 according to this embodiment, the oil return flow rate is controlled by the flow rate control device 20 according to this embodiment controlling the operation of the flow rate adjusting device 50. The flow control device 20 includes an operation state determination unit 21, a control parameter calculation unit 22, an oil return flow determination unit 23, an oil return control unit 24, and a storage unit 26. These are connected to the input port 27 and the output port 28. Thereby, the driving | running state determination part 21, the control parameter calculation part 22, the oil return flow rate determination part 23, and the memory | storage part 26 are comprised so that data can be exchanged mutually.

  The input port 27 is connected with a compressor inlet pressure sensor 41, a rotation speed sensor 42, a compressor outlet pressure sensor 43, an oil temperature sensor 44, and other sensors for acquiring information related to oil return control according to this embodiment. Has been. Further, the output port 28 is connected to a control target such as the on-off valves 52A and 52B of the flow rate adjusting device 50. As a result, the control parameter calculation unit 22, the oil return flow rate determination unit 23, etc. acquire information necessary for oil return control according to this embodiment from the various sensors, and based on this information, return information according to this embodiment. Perform oil control.

  The storage unit 26 stores a computer program including a processing procedure of oil return control according to this embodiment and data necessary for controlling the operation of the flow rate adjusting device 50. Here, the storage unit 26 can be configured by a volatile memory such as a RAM (Random Access Memory), a nonvolatile memory such as a flash memory, or a combination thereof. Further, the control parameter calculation unit 22, the oil return flow rate determination unit 23, and the like can be configured by a memory and a CPU.

  The computer program can realize the processing procedure of the control method of the air conditioner according to this embodiment by combining with the computer program already recorded in the operation state determination unit 21 and the oil return flow rate determination unit 23 and the like. There may be. In addition, the flow control device 20 uses dedicated hardware instead of the computer program, and an operation state determination unit 21, a control parameter calculation unit 22, an oil return flow determination unit 23, and an oil return provided in the flow control device 20. The function of the control unit 24 may be realized. Next, a procedure for realizing oil return control according to this embodiment using the flow rate control device 20 will be described. In the following description, please refer to FIGS. 1 and 3 as appropriate.

  FIG. 4 is a flowchart showing the procedure of oil return control according to this embodiment. In the oil return control according to this embodiment, as shown in FIG. 3, the flow rate adjusting device 50 for adjusting the oil return flow rate to the compressor 30 includes a first capillary 50A and a second capillary 50B connected in parallel, The first on-off valve 52A and the second on-off valve 52B are provided on the oil separator 37 side of the first and second capillaries 51A, 51B. In addition, in FIG. 3, although the strainer which is a dust removal means is not provided, you may provide this.

  The throttle amount of the first capillary 51A is larger than the throttle amount of the second capillary 51B. That is, the flow rate of oil flowing through the first capillary 51A is smaller than the flow rate of oil flowing through the second capillary. In principle, the flow rate adjusting device 50 can adjust the oil return flow rate in four stages. That is, when oil does not flow through either of the first and second capillaries 51A and 51B (oil return flow rate = 0), when oil flows only through the first capillary 51A (oil return flow rate = A), the second capillary 51B There are four stages: flowing oil only (oil return flow rate = B) and flowing oil through the first and second capillaries 51A and 51B (oil return flow rate = A + B). Here, the relationship of the oil return flow rate at each stage is A + B> B> A> 0.

  In this embodiment, the first and second on-off valves 52A and 52B are electromagnetic ON-OFF valves. The first and second on-off valves 52 </ b> A and 52 </ b> B are controlled to be opened / closed by a command from the oil return control unit 24 of the flow control device 20. Thereby, the oil return flow rate to the compressor 30 is adjusted. For example, if both the first and second on-off valves 52A and 52B are closed, the oil return flow rate becomes 0, and if only the first on-off valve 52A is opened, the oil return flow rate becomes A. And if only the 2nd on-off valve 52B is opened, the oil return flow rate will be B, and if both the 1st and 2nd on-off valves 52A and 52B are opened, the oil return flow rate will be A + B.

  In executing the oil return control according to this embodiment, the operation state determination unit 21 included in the flow control device 20 determines whether or not the operation state of the air conditioner 1 is in transition (step S101). Here, the time of transition is a case where the operating state of the air conditioner 1 fluctuates rapidly. For example, when the compressor 30 is started up or when the compressor rotational speed Nc of the compressor 30 is suddenly increased to rapidly increase the refrigerant circulation amount, it corresponds to a transient time. In the case where the compressor 30 includes the refrigerant discharge capacity control structure, the case where the refrigerant discharge capacity is switched corresponds to a transition time. Also, switching between cooling and heating corresponds to a transition time.

  During the transition, when the compressor rotation speed Nc of the compressor 30 changes abruptly, particularly when the compressor rotation speed Nc increases rapidly, the amount of oil in the compressor 30 may decrease. As a result, there is a possibility that the sliding portion in the compressor 30 may be insufficiently lubricated. Therefore, when the operating state of the compressor 30 is in a transient state (step S101: Yes), the oil return flow rate is set to the maximum (step S106). In this embodiment, the oil return flow rate determination unit 23 sets the oil return flow rate to the maximum, and based on this set value, the oil return control unit 24 fully opens both the first and second on-off valves 52A and 52B. The maximum oil return flow rate is controlled (step S105). As a result, a sufficient amount of oil is returned to the compressor 30, so that insufficient lubrication of the compressor 30 during the transition can be avoided. Here, whether or not it is in transition is determined to be in transition when, for example, the rotational fluctuation of the compressor rotational speed Nc exceeds a predetermined threshold value.

  When the operation state of the compressor 30 is not in a transient state (step S101: No), the operation state determination unit 21 included in the flow control device 20 determines whether or not the compressor 30 is stopped from the operation state ( Step S102). When the oil is returned from the oil separator 37 to the compressor 30 after the compressor 30 is stopped from the operating state, the amount of oil in the compressor 30 may increase and the compressor 30 may be filled with oil. When the compressor is restarted in this state, the compressor 30 compresses oil (liquid), which may reduce the durability of the compressor 30. In particular, in an air conditioner including a plurality of compressors, when some of the compressors are stopped, a phenomenon in which the amount of oil in the stopped compressors increases significantly appears.

  Therefore, in this embodiment, when the compressor 30 stops from the operating state (step S102: Yes), the oil return flow rate is set to 0 (step S107). In this embodiment, the oil return flow determination unit 23 sets the oil return flow rate to 0, and based on this set value, the oil return control unit 24 fully closes both the first and second on-off valves 52A and 52B. As a result, the oil return flow rate is controlled to be 0 (step S105). Thereby, after the compressor 30 is stopped, the amount of oil in the compressor 30 can be prevented from increasing more than necessary, so that a decrease in the durability of the compressor 30 due to oil compression can be suppressed.

  When it is not when the compressor 30 stops from the operating state (step S102: No), that is, when the operation of the compressor 30 is continued, the oil return flow rate suitable for the operating state of the compressor 30 at that time is used. In order to return oil, the control parameter calculation unit 22 calculates a control parameter (step S103). Here, in this embodiment, the oil return flow rate is determined based on at least the circulation amount of the refrigerant that is discharged from the compressor 30 and circulates in the refrigerant circuit. More specifically, the oil return flow rate is increased as the circulation amount of the refrigerant increases. Thereby, the amount of oil suitable for the operating state of the compressor 30 can be returned.

  In this embodiment, the circulation amount of the refrigerant is represented by a refrigerant circulation amount parameter QQ obtained by the product of the compressor rotation speed Nc and the compressor inlet pressure Pi of the refrigerant. The refrigerant circulation amount parameter QQ is a parameter related to the circulation amount of the refrigerant discharged from the compressor 30 and is a control parameter. If the oil return flow rate is large when the compressor rotational speed Nc is small, excess oil will be returned to the compressor 30, and the durability of the compressor 30 may be reduced by oil compression. On the other hand, if the oil return flow rate is small when the compressor rotational speed Nc is large, the oil in the compressor 30 may be insufficient, leading to insufficient lubrication.

  Since the refrigerant circulation rate parameter QQ includes the compressor rotation speed Nc, if the oil return flow rate is increased as the refrigerant circulation volume parameter QQ increases, an appropriate flow rate from when the compressor rotation speed Nc is small to when it is large. Oil can be returned to the compressor 30. Further, when the compressor inlet pressure Pi included in the refrigerant circulation amount parameter QQ is increased, the refrigerant density is increased. As a result, the amount of oil discharged from the compressor 30 is increased, so that much oil is returned. There is a need. In the refrigerant circulation amount parameter QQ used in this embodiment, the influence of the refrigerant density can be taken into account by the compressor inlet pressure Pi, so that the refrigerant circulation amount can be more accurately reflected and the operation state of the compressor 30 can be reflected. Therefore, a more preferable oil return flow rate can be determined.

  In particular, in an air conditioner including a plurality of compressors, the compressor rotation speed and the refrigerant circulation amount are not proportional to each other. However, considering the influence of the refrigerant density by the compressor inlet pressure Pi, the compressor 30 can be operated. On the other hand, a more preferable oil return flow rate can be set. Furthermore, since the compressor inlet pressure Pi is determined by the outside air temperature, when the air conditioner is used in an environment where the temperature difference between the warm and warm temperatures is large, the operation of the compressor 30 is performed by considering the compressor inlet pressure Pi. A more preferable oil return flow rate can be set for the state.

  In this embodiment, the oil return flow rate may be determined based on at least the refrigerant circulation amount parameter QQ. Furthermore, the product of the pressure difference ΔP (Po−Pi) of the compressor 30 and the inverse of the oil viscosity μ. (ΔP / μ) may be added as a control parameter. Here, ΔP / μ is defined as a differential pressure parameter PP relating to a differential pressure between the refrigerant pressure at the compressor outlet and the refrigerant pressure at the compressor inlet. The high / low differential pressure ΔP is obtained by the difference between the refrigerant compressor outlet pressure Po and the compressor inlet pressure Pi (Po> Pi). Based on the obtained differential pressure parameter PP, the oil return flow rate is increased as the differential pressure parameter PP decreases.

  As the height difference pressure ΔP decreases, the oil becomes less likely to flow through the flow path. Therefore, as the height difference pressure ΔP decreases, the flow rate adjusting device 50 increases the oil return flow rate. In this embodiment, a capillary with a smaller drawing amount is used. For example, from the state where only the first capillary 50A is used, it is switched to only the second capillary 50B, or to both the first and second capillaries 50A and 50B. Moreover, when using a flow regulating valve, the opening degree is enlarged. As a result, when the height difference pressure ΔP is small, the amount of oil returned to the compressor 30 can be secured, and insufficient lubrication can be suppressed.

  On the other hand, the greater the elevation differential pressure ΔP, the easier it is for oil to flow through the flow path. Therefore, as the elevation differential pressure ΔP increases, the flow rate adjusting device 50 decreases the oil return flow rate. In this embodiment, a capillary with a larger drawing amount is used. For example, from the state where the first and second capillaries 50A and 50B are used, switching to only the second capillary 50B or switching to only the first capillary 50A is performed. Moreover, when using a flow regulating valve, the opening degree is made small. As a result, when the height difference pressure ΔP is large, it is possible to suppress the return of excessive oil to the compressor 30 and reduce the possibility of oil compression.

  Thus, the flow rate adjusting device 50 controls the oil return flow rate to be constant based on the differential pressure parameter PP. As a result, the flow rate adjusting device 50 can keep the flow rate of the oil returned from the oil separator 37 to the compressor 30 constant regardless of the magnitude of the differential pressure parameter PP. As a result, an appropriate amount of oil can be returned to the compressor 30 according to the operating conditions of the compressor 30. In addition, a more preferable oil return flow rate can be set with respect to the operating state of the compressor 30 by considering the oil viscosity μ. Next, in this embodiment, a procedure for obtaining the oil return flow rate from the calculated control parameter will be described.

  5-1 is explanatory drawing which shows an example of the oil return flow rate determination map used in order to determine the oil return flow rate in the oil return control which concerns on this Example. In the oil return flow determination map 60, the control parameter is described with the differential pressure parameter PP on the vertical axis and the refrigerant circulation amount parameter QQ on the horizontal axis. Here, the oil return flow rate determination map 60 is stored in the storage unit 26 of the flow rate control device 20.

  When calculating the differential pressure parameter PP, the control parameter calculation unit 22 acquires the compressor outlet pressure Po from the compressor outlet pressure sensor 43 and acquires the compressor inlet pressure Pi from the compressor inlet pressure sensor 41. Based on this, the height difference pressure ΔP is calculated. Further, the control parameter calculation unit 22 obtains the temperature Tc of the oil returned to the compressor 30 from the oil temperature sensor 44 provided in the oil separator 37, and based on this, obtains the viscosity μ of the oil returned to the compressor 30. calculate. Then, a differential pressure parameter PP is calculated from the obtained high / low differential pressure ΔP and viscosity μ.

  Further, the control parameter calculation unit 22 acquires the compressor rotation speed Nc from the rotation speed sensor 42, acquires the compressor inlet pressure Pi from the compressor inlet pressure sensor 41, and sets the refrigerant circulation amount parameter QQ = Nc × Pi. calculate. Here, the compressor inlet pressure Pi included in the refrigerant circulation amount parameter QQ is also used when calculating the differential pressure parameter PP.

  When the control parameter calculation unit 22 calculates the refrigerant circulation amount parameter QQ and the differential pressure parameter PP, the oil return flow rate determination unit 23 converts the refrigerant circulation amount parameter QQ and the differential pressure parameter PP determined by the control parameter calculation unit 22 into the oil return. This is given to the flow rate determination map 60. The oil return flow determination map 60 describes the oil return flow rate corresponding to the differential pressure parameter PP and the refrigerant circulation amount parameter QQ.

In this embodiment, as shown in Figure 5-1, the oil return flow determination map 60, the first oil return flow rate control lines SL ₁ and the second oil return flow rate control line SL _2, the oil return flow rate three stages It is described in. That is, the region defined by the vertical axis and the first oil return flow change line SL ₁ has an oil return flow rate A, and the first oil return flow change line SL ₁ and the second oil return flow change line SL ₂ In the specified region, the oil return flow rate is B. The area defined by the first oil return flow rate control line SL ₁ and the vertical axis the oil return flow rate is A + B. In this way, the oil return flow changes at the first oil return flow rate change line SL ₁ and the second oil return flow rate change line SL ₂ . Here, as described above, A + B>B> A.

For example, the control amount of refrigerant circulation parameters QQ calculated by the parameter calculation unit 22 is QQ _1, when the differential pressure parameter PP is PP _1, coordinates Qr ₁ (QQ ₁ determined by the QQ ₁ and PP _1, The oil return flow rate described in the region where PP ₁ ) exists is the oil return flow rate at this time. The oil return flow rate is B in the oil return flow rate determination map 60 shown in FIG. As described above, when the refrigerant circulation amount parameter QQ and the differential pressure parameter PP are given, the oil return flow rate determination map 60 returns the corresponding oil return flow rate to the oil return flow rate determination unit 23. As a result, the oil return flow rate can be determined according to the refrigerant circulation amount parameter QQ and the differential pressure parameter PP.

  The oil return flow determination unit 23 receives the determined oil return flow rate from the oil return flow determination map 60, and the oil return flow rate is determined (step S104). The oil return control unit 24 controls the flow rate adjusting device 50 so that the determined oil return flow rate is obtained. When the oil return flow rate is B, it is only necessary to return oil using only the second capillary 51B of the flow rate adjusting device 50 (FIG. 3), so the oil return control unit 24 opens only the second on-off valve 52B. Thereby, the oil return flow rate can be controlled so that the oil is returned to the compressor 30 at the oil return flow rate B (step S105).

Here, in the oil return flow determination map 60 shown in FIG. 5A, the region where the oil return flow rate is A has the smallest oil return flow rate. In this region, when a return oil flow rate smaller than the return oil flow rate A is required (for example, a region indicated by C in FIG. 5A), by adjusting the valve opening time of the first on-off valve 52A within a predetermined time. That is, the oil return flow rate can be adjusted to be smaller by controlling the first on-off valve 52A on and off. Also, in the vicinity of the first oil return flow rate change line SL ₁ and the second oil return flow rate change line SL ₂ , by adjusting the valve opening time of the first on-off valve 52A and the second on-off valve 52B for a predetermined time, The oil flow rate can be changed continuously.

  5-2 is explanatory drawing which shows the other example of the return oil flow rate determination map used in order to determine the return oil flow rate in the return oil control which concerns on this Example. When the oil return flow determination map 60 ′ is used to control the oil return flow by the flow rate adjusting device 50 shown in FIG. 2-1, the oil return flow determination map 60 ′ is used to increase the oil return flow. The timing for changing the flow rate and the timing for changing the oil return flow rate when the oil return flow rate is decreased can be made different. That is, hysteresis can be given to the change in the oil return flow rate. This means that the way of changing the oil return flow rate varies depending on the path of the change.

In the oil return flow determination map 60 'shown in Figure 5-2, the first oil return flow rate control line SL ₁ and a second oil return flow rate control line SL _2, and an ideal oil return flow changes line. This oil return flow rate determination map 60 'is a sub first nearer vertical axis than the first oil return flow rate change line SL ₁ in addition to the first oil return flow rate change line SL ₁ and the second oil return flow rate change line SL ₂ . 'and the longitudinal axis toward the sub-second oil return flow rate control line SL ₂ than the second oil return flow rate control line SL _2' oil return flow change line SL ₁ is described. When the oil return flow rate is increased, the oil return flow rate is switched by the first oil return flow rate change line SL ₁ (arrow AB in FIG. 5-2). The oil return flow rate is changed by the oil flow rate change line SL ₁ ′ (arrow AB in FIG. 5-2). That is, in this embodiment, when the oil return flow rate is decreased, the timing for changing the oil return flow rate is shifted to a region where the oil return flow rate is smaller than the timing when the oil return flow rate is changed when the oil return flow rate is increased. To do.

Here, when only the first return oil flow rate change line SL ₁ and the second return oil flow rate change line SL ₂ are described as in the return oil flow rate determination map 60 (FIG. 5-1), the first return oil rate in the vicinity of the flow rate control line SL ₁ and the second oil return flow rate control line SL _2, often the first on-off valve 52A and the second on-off valve 52B is opened and closed. As a result, there is a risk that the durability of the life of the first on-off valve 52A and the like may be reduced. However, if hysteresis is given to the change in the oil return flow as shown in the oil return flow determination map 60 ′, the opening / closing frequency of the first on / off valve 52A and the like can be reduced, so that the durability of the first on / off valve 52A and the like is reduced. Can be suppressed.

FIG. 6 is an explanatory diagram illustrating another example of a return oil flow rate determination map used for determining the return oil flow rate in the return oil control according to this embodiment. This oil return flow rate determination map 60a is used when the oil return flow rate is determined using the flow rate adjusting device 50a shown in FIG. The flow control device 50a is opening OV ₁₁ of the flow control valve 53 as a oil return flow rate corresponding to the combination of the differential pressure parameters PP and the refrigerant circulation amount parameter QQ, OV _kl, etc. are described. Then, when the refrigerant circulation amount parameter QQ and the differential pressure parameter PP calculated by the control parameter calculation unit 22 are given, the oil return flow determination map 60a returns the corresponding oil return flow rate to the oil return flow determination unit 23. It is like that.

For example, when the refrigerant circulation amount parameter calculated by the control parameter calculation unit 22 is QQ ₁ and the differential pressure parameter is PP ₂ , the opening degree of the flow rate adjustment valve 53 corresponding to this is OV ₂₁ . An oil return control unit 24 opens the flow control valve 53 in this opening OV _21. Thereby, the oil return flow rate can be adjusted. Although the opening degree of the flow rate adjusting valve 53 is described discretely, the opening degree of the flow rate adjusting valve 53 that is not described in the oil return flow rate determination map 60a is, for example, linear interpolation or the like using the opening degree on both sides. Can be obtained.

  As described above, in this embodiment, the refrigerant circulation amount parameter relating to the circulation amount of the refrigerant discharged from the compressor is used, and the flow rate of oil returned from the oil separator to the compressor is increased as the refrigerant parameter increases. Thereby, an appropriate amount of oil corresponding to the operating state of the compressor provided in the air conditioner can be returned to the compressor. As a result, it is possible to minimize a decrease in compression efficiency of the compressor while suppressing poor lubrication of the compressor. In particular, when the capacity of the oil sump provided in the compressor is small (for example, a compressor of a type driven by external power), the oil return flow rate is easily affected. An appropriate amount of oil according to the operating state of the compressor can be returned to the compressor. Thereby, the influence of the change in the oil return flow rate can be minimized.

  In addition, since an appropriate amount of oil according to the operating state of the compressor can be returned to the compressor, the amount of oil flowing out to the refrigerant circuit of the air conditioner is minimized, and the entire air conditioner is A decrease in thermal efficiency can be suppressed. Furthermore, since the amount of oil flowing out to the refrigerant circuit of the air conditioner can be suppressed to a minimum, the frequency of so-called oil return operation for returning the oil flowing out into the piping of the air conditioner and each device to the compressor can also be reduced. Therefore, the air conditioning feeling is also improved.

  As described above, the flow rate adjusting device and the air conditioner according to the present invention are useful for the compressor included in the air conditioner, and are particularly suitable for returning the lubricating oil to the compressor included in the air conditioner.

It is a composition conceptual diagram showing the air harmony device concerning this example. It is explanatory drawing which shows the flow volume adjustment apparatus which concerns on this Example. It is explanatory drawing which shows the other structural example of the flow volume adjustment apparatus which concerns on this Example. It is explanatory drawing which shows the structure of the flow control apparatus which concerns on this Example. It is a flowchart which shows the procedure of the oil return control which concerns on this Example. It is explanatory drawing which shows an example of the return flow determination map used in order to determine the return flow in the return control which concerns on this Example. It is explanatory drawing which shows the other example of the return flow determination map used in order to determine the return flow in the return control which concerns on this Example. It is explanatory drawing which shows the other example of the return flow determination map used in order to determine the return flow in the return control which concerns on this Example.

Explanation of symbols

1 Air conditioner (air conditioner)
DESCRIPTION OF SYMBOLS 20 Flow control apparatus 21 Operation state determination part 22 Control parameter calculation part 23 Oil return flow determination part 24 Oil return control part 26 Memory | storage part 30 Compressor 31 Gas engine 37 Oil separator 41 Compressor inlet pressure sensor 42 Rotation speed sensor 43 Compression Machine outlet pressure sensor 44 Oil temperature sensor 50, 50a Flow rate adjusting device 50A First capillary 50B Second capillary 52A First on-off valve 52B Second on-off valve 53 Flow rate adjusting valve 54 Strainer 60, 60 ', 60a Return oil flow rate determination map

Claims (7)

And compressors, is disposed between the oil separator lubricating oil contained in the refrigerant discharged is compressed by the compressor is separated from the refrigerant, to the circulating amount of the refrigerant discharged from the compressor accordance refrigerant circulation amount parameter becomes larger, a Ru flow amount adjusting device increases the flow rate of the lubricating oil from the oil separator back to said compressor,
Based on a differential pressure parameter relating to a differential pressure between the refrigerant pressure at the outlet of the compressor and the refrigerant pressure at the inlet of the compressor, the flow rate of the lubricating oil returning from the oil separator to the compressor is kept constant. To work
The differential pressure parameter includes a high / low differential pressure obtained by a difference between a refrigerant pressure at the compressor outlet and a refrigerant pressure at the compressor inlet, and a lubricant oil returned from the oil separator to the compressor. A flow rate adjusting device characterized by being a product of a reciprocal of viscosity.   2. The flow rate adjusting device according to claim 1, wherein the refrigerant circulation amount parameter is a product of a rotation speed of the compressor and a pressure of the refrigerant at an inlet of the compressor. A plurality of fluid throttle means and a plurality of flow path opening / closing means, wherein the fluid throttle means are connected in parallel to each other, and the flow path opening / closing means is connected in series to each of the fluid throttle means. The flow rate adjusting device according to claim 1 or 2, wherein Wherein when the operation of the compressor is transient time, the flow rate according to any one of claims 1 to 3, wherein the maximum and to Rukoto the flow rate of the lubricating oil returned to the compressor from the oil separator Adjustment device. When said compressor is stopped, the flow rate adjustment device according to any one of claims 1 to 4, characterized that you zero the flow rate of the lubricating oil returned to the compressor from the oil separator . Timing for changing the flow rate when increasing the flow rate of lubricating oil returning from the oil separator to the compressor, and timing for changing the flow rate when decreasing the flow rate of lubricating oil returning from the oil separator to the compressor flow rate control device according to any one of claims 1 to 5, wherein Rukoto varied and. A compressor that compresses and discharges the refrigerant;
  An oil separator for separating lubricating oil contained in the refrigerant discharged from the compressor from the refrigerant;
  A flow rate adjustment device according to any one of claims 1 to 6,
  A condenser for condensing and liquefying the refrigerant discharged from the compressor;
  An expansion valve for depressurizing and expanding the refrigerant liquefied by the condenser;
  An evaporator that exchanges heat between the refrigerant that has passed through the expansion valve and the air;
  An air conditioner comprising:

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