JP4456506B2 - Engine driven heat pump - Google Patents

Description

  The present invention relates to a technology of an engine-driven heat pump having a function of suppressing refrigerant stagnation in a compressor.

  A compressor provided in an air conditioner, a refrigerator, a chilled water machine, a dehumidifier, or the like is filled with refrigerant in the system together with a refrigerant as a lubricating oil for performing a compression process for lubrication. Generally, as the refrigerating machine oil, a mineral oil or a synthetic oil having a property of being mutually soluble with the refrigerant is selected. There is a difference in the solubility of the refrigerant in the refrigerating machine oil depending on the type, pressure, and temperature of the refrigerant, but the solubility increases as the temperature or pressure increases.

  The refrigerant stagnation means that the liquid refrigerant is dissolved in the oil sump in the stopped compressor. At this time, as described above, when the oil temperature is low, the ratio of the refrigerant dissolved in the refrigerating machine oil increases. Usually, since the compressor is installed in the outdoor unit of the air conditioner, the ambient temperature of the compressor is low when the outdoor air is left for a while under low conditions, and the refrigerating machine oil in the oil reservoir inside the compressor is It is low temperature. Here, with the passage of time, the liquid refrigerant dissolves in the refrigeration oil in the oil sump.

  The compressor in the refrigerant stagnation state described above generates the following problems at the time of startup. That is, starting the compressor while a large amount of the refrigerant liquid is dissolved in the refrigerating machine oil in the oil reservoir inside the compressor causes the compressor to undergo liquid compression, resulting in excessive shaft torque and failure of the compressor. Furthermore, when a large amount of refrigerant liquid is started while being dissolved in the refrigerating machine oil in the oil reservoir inside the compressor, intense bubbling occurs such that the dissolved refrigerant liquid suddenly vaporizes and the oil boils (oil forming phenomenon). At this time, a large amount of refrigerating machine oil is discharged at a time, resulting in a defective compressor lubricating oil, leading to a compressor failure.

Here, in order to prevent the above-described refrigerant stagnation, a heater is provided in the compressor and the heater is turned on when the compressor stop time is longer than a certain value, or when the temperature of the compressor and the suction pipe is less than a certain temperature. The technology of an air conditioner characterized by starting operation while being energized is known (see Patent Document 1). On the other hand, for the purpose of ensuring the durability of the entire multi-compressor system, in an air conditioner equipped with a plurality of compressors, on average, the load at the time of startup is not biased to a specific compressor. The technique of the air conditioning apparatus provided with the control apparatus to bear is publicly known (refer patent document 2).
JP-A-8-261571 JP-A-7-198213

  The problem to be solved by the present invention is to suppress the stagnation of the refrigerant in the engine-driven heat pump in which the engine and the compressor are housed in the engine room. This is to prevent the oil from rising due to the forming phenomenon and excessive bearing torque due to liquid compression.

  For example, after an air conditioner equipped with an engine-driven heat pump has been installed and the engine has been stopped for a long period of time when the outside air temperature is low, the compressor provided in the air conditioner has an ambient temperature of Since it is low, the refrigerant is stagnation. For example, an air conditioner equipped with an engine-driven heat pump may be constructed by connecting a plurality of indoor units with one large-capacity outdoor unit. At this time, the outdoor unit is provided with a plurality of compressors for one engine. Here, in the case where only some indoor units are operated without operating all the connected indoor units (light load operation), some of the compressors provided in the outdoor units are not operated and some of the compression is performed. Operate only the machine. At this time, the compressor that has been stopped for a long time at a low ambient temperature is in the refrigerant stagnation state. Here, as described above, starting the refrigerant stagnation compressor causes oil rising due to an oil forming phenomenon or excessive bearing torque due to liquid compression, which causes a compressor failure.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

According to claim 1, in an engine-driven heat pump in which an engine and two compressors are housed in an engine room and a ventilation fan is provided in the engine room, only one of the compressors is driven during heating operation. By stopping the ventilation fan when the temperature of the chamber is lower than a predetermined temperature, the temperature in the engine chamber is increased by engine waste heat , and refrigerant stagnation in the stopped compressor is suppressed , and the compressor has an oil sump In the case where the stop time of the two compressors exceeds a predetermined time, the compressor having the oil sump is driven first .

  As effects of the present invention, the following effects can be obtained.

According to claim 1, in an engine-driven heat pump in which an engine and two compressors are housed in an engine room and a ventilation fan is provided in the engine room, only one of the compressors is driven during heating operation. By stopping the ventilation fan when the temperature of the chamber is lower than a predetermined temperature, the temperature in the engine chamber is increased by engine waste heat , and refrigerant stagnation in the stopped compressor is suppressed , and the compressor has an oil sump When the stop time of the two compressors exceeds a predetermined time, the compressor having the oil sump is driven first. By starting the compressor from a large number of compressors, it is possible to prevent oil from rising and to prevent the compressor from malfunctioning.

  Next, embodiments of the invention will be described.

  FIG. 1 is a refrigerant circuit diagram of an embodiment according to the present invention.

  FIG. 2 is a simplified diagram of oil dilution with respect to elapsed time.

  FIG. 3 is a refrigerant circuit diagram of another embodiment according to the present invention.

  FIG. 4 is a simplified diagram of changes in pressure when the compressor is started with respect to elapsed time.

  First, a refrigerant circuit configuration of an engine-driven heat pump having an engine room 43 provided with two compressors 2a and 2b and one engine 22 in the outdoor unit 40 will be described with reference to FIG.

  The engine-driven heat pump is connected to the compressors 2a and 2b that obtain power from the engine 22 as a driving source and compresses the refrigerant, and is connected to the discharge side of the compressors 2a and 2b, and switches the refrigerant flow during cooling and heating. The four-way valve 3, the outdoor heat exchanger 4 to which refrigerant is supplied from the compressors 2a and 2b through the four-way valve 3 during cooling, and the refrigerant from the compressors 2a and 2b through the four-way valve 3 during heating It has an indoor heat exchanger 5, an outdoor heat exchanger 4 and an outdoor heat exchanger expansion valve 6 disposed between the indoor heat exchangers 5, and uses a refrigerant cycle composed of these. is there. The four-way valve 3 is composed of an electromagnetic switching valve, and is connected to a control device 30 serving as a control means, and is switched in the case of heating, cooling, defrosting, etc. by operation of the operation means 31.

  The compressors 2a and 2b suck and compress gas refrigerant from the suction side, and discharge high-temperature and high-pressure gas refrigerant. On the other hand, the four-way valve 3 is connected to the discharge side of the compressors 2a and 2b via a path 9 constituting a discharge line. The path 9 separates refrigeration oil contained in the gas refrigerant. An oil separator 8 for returning to the suction side of the compressor 2 is provided. That is, the gas refrigerant discharged from the compressor 2 flows into the four-way valve 3 through the oil separator 8 and is guided in a predetermined direction by the four-way valve 3. Further, since the gas refrigerant sucked into the compressors 2a and 2b is also guided by the four-way valve 3, the refrigerant suction side of the compressors 2a and 2b and the four-way valve 3 are connected by a path 10 constituting a suction line. .

  The four-way valve 3 is connected to one end side of the indoor heat exchanger 5, and the refrigerant liquid receiver 7 is connected to the other end side of the indoor heat exchanger 5. Similarly, the outdoor heat exchanger 4 is connected to the four-way valve 3, and the outdoor heat exchanger expansion valve 6 is connected to a path 13 connecting the outdoor heat exchanger 4 and the indoor heat exchanger 5. Is provided.

  The engine room 43 includes two compressors 2 a and 2 b, an engine 22, and a ventilation fan 19. The power of the engine 22 is connected so as to be transmitted to the two compressors 2a and 2b by a belt-type power transmission mechanism 23 including a pulley, a belt and the like. However, the power transmission mechanism is not limited and may be a chain type or a gear type. Here, the control means 30 can connect / disconnect the transmission power of each compressor 2a or 2b by the separate electromagnetic clutch 21a or 21b. The electromagnetic clutch 21a or 21b is disposed between the drive shaft of the compressor 2a or 2b and the pulley. Moreover, the control means 30 can turn on / off the heater 25a or 25b which can heat the oil sump inside a compressor. Further, the engine room 43 is provided with a temperature sensor 24 for measuring the ambient temperature in the engine room and connected to the control means 30.

  Here, the heating operation according to the present invention will be described using the refrigerant circuit of FIG. The description of the cooling operation is omitted here.

  During the heating operation, the high-temperature and high-pressure gas refrigerant compressed and discharged by the compressors 2 a and 2 b is sent to the indoor heat exchanger 5 through the four-way valve 3, and the indoor heat exchanger 5 It is condensed by releasing heat to the indoor air blown by 18, and this condensation heat is released into the indoor air and warms the indoor air. Here, the refrigerant changes from gas to liquid. Then, the liquefied refrigerant flows into the liquid refrigerant receiver 7 from the liquid refrigerant receiver inlet 19a through the check valve 15, reaches the outdoor expansion valve 6 from the liquid refrigerant receiver outlet 19b, and this outdoor expansion valve 6. In this state, the pressure is suddenly reduced and is easily evaporated, and is led to the outdoor heat exchanger 4. This outdoor heat exchanger 4 becomes an evaporator, and the refrigerant takes heat of evaporation from the outdoor air, and a part of the refrigerant changes from liquid to gas. The refrigerant evaporated through the outdoor heat exchanger 4 passes through the path 10 via the four-way valve 3 and is sucked and compressed by the compressors 2a and 2b and then discharged again.

  Now, examples according to the present invention will be described. In this embodiment, the operation of the air conditioner when the outside air temperature is low, that is, the heating operation is described for the purpose of suppressing the refrigerant stagnation of the present invention. However, the following embodiments are the same even in the cooling operation. Needless to say.

  During the heating operation when the outside air temperature is low, when the compressor 2a (or 2b) is stopped according to the heating load in the room, the temperature sensor 24 installed in the engine room 43 of the outdoor unit 40 is set with the setting device 32. If the temperature is lower than the predetermined temperature set in, the control means 30 stops the operation of the ventilation fan 19 installed in the engine room 43. As a result, the temperature in the engine room rises due to the waste heat of the engine, and the refrigerant stagnation in the stopped compressor 2a (or 2b) can be suppressed. On the other hand, there is a possibility that the equipment / device in the engine room is deteriorated or damaged due to an abnormal temperature rise. Therefore, if the temperature sensor 24 is higher than the predetermined temperature set by the setting device 31, the control device 30 operates the ventilation fan 19. The abnormal temperature rise of the engine room 43 is prevented.

  Next, during the heating operation when the outside air temperature is lower than the set temperature, when one of the compressors 2a (or 2b) is stopped according to the indoor heating load, it is set by the setting device 32 When the predetermined operation time A elapses, the control means 30 disconnects the clutch 21b (or 21a), stops the operating compressor 2b (or 2a), and connects the other clutch 21a (or 21b). Then, the compressor 2a (or 2b) that has been stopped is operated. Refrigerant stagnation is suppressed by setting the stop time of the compressor 2a (or 2b) to a predetermined time or less.

  Here, the aforementioned predetermined time A will be described with reference to FIG. FIG. 2 simply shows the relationship between the oil dilution and the general elapsed time under a certain temperature and pressure condition. Here, the oil dilution is the ratio of the refrigerating machine oil to the refrigerant and the refrigerating machine oil dissolved in the oil reservoir in the compressor 2a (or 2b) (oil dilution degree [%] = (oil amount [g]). / (Oil amount [g] + refrigerant amount [g])). As shown in FIG. 2, generally, the oil dilution does not become lower after reaching a certain time (point a). That is, if the predetermined time is exceeded under a certain temperature / pressure condition, the refrigerant does not dissolve in the refrigerating machine oil any more. Here, the predetermined time A is obtained experimentally and stored in the memory of the control means 30 as a map.

  Further, during the heating operation when the outside air temperature is lower than the set temperature, when the compressor 2a (or 2b) is stopped according to the indoor heating load, the predetermined time A set by the setting device 32 is set. In the case of exceeding the above, the control means 30 energizes the heater 25a (or 25b) provided separately to the compressor 2a (or 2b) to heat the oil sump of the compressor 2a (or 2b). Refrigerant stagnation is suppressed by heating the refrigerating machine oil accumulated in the oil sump. When the temperature in the engine room 43 exceeds the set temperature, the energization of the heater 25 is stopped.

  Here, out of the two compressors 2a and 2b, the compressor 2a is a compressor without a sump, and the compressor 2b is a compressor with a sump. When the stop time of the two compressors 2a and 2b exceeds the predetermined time A set by the setting device 32, the compressor 2b having a sump is first operated at the time of start-up to prevent oil from rising. .

  Next, an embodiment according to the present invention of an engine-driven heat pump having an engine room 43 provided with one compressor 2 and one engine 22 in the outdoor unit 40 will be described. In addition, about a refrigerant circuit structure and the description at the time of heating operation, it is equivalent to the above-mentioned, and description is abbreviate | omitted. Further, in this embodiment, the operation of the air conditioner when the outside air temperature is low, that is, the heating operation is described because of the problem of suppressing the refrigerant stagnation of the present invention, but the following embodiments are the same even in the cooling operation. Needless to say.

  In the heating operation activation when the outside air temperature is low, when the stop time of the compressor 2 exceeds the predetermined time A set by the setting device 32, the clutch 21 is activated while being connected. That is, since the engine 22 is operated with a load applied immediately after the start, the rapid start-up of the compressor 2 can be suppressed, and the occurrence of oil rising due to an oil forming phenomenon or excessive shaft torque due to liquid compression can be prevented.

  In the heating operation start-up when the outside air temperature is low, when the stop time of the compressor 2 exceeds the predetermined time A set by the setting device 32, the engine 22 is set to the predetermined time B and the predetermined low time set by the setting device 32. Start at the number of revolutions. That is, it is possible to prevent the compressor 2 from starting suddenly, and to prevent the oil rising due to the oil forming phenomenon or the occurrence of excessive shaft torque due to liquid compression.

  If the stop time of the compressor 2 exceeds the predetermined time A set by the setting device 31 at the start of heating operation when the outside air temperature is low, the control device 30 causes the engine to operate for the predetermined time B set by the setting device 32. The power transmitted to the compressor 2 is cut off by the clutch 21. As a result, the engine room 43 rises in temperature due to the exhaust heat of the engine that is in operation and can suppress the stagnation of the refrigerant.

  Here, the predetermined time B described above will be described with reference to FIG. FIG. 4 simply shows the change in pressure at the start of the compressor with respect to the elapsed time. Here, P2 shows the behavior of the high pressure and P1 shows the behavior of the low pressure. Originally, the pressure change with a high-low pressure difference at the same time as the start is represented by a solid line α. On the other hand, a pressure change that suppresses rapid start-up of the compressor 2 in the above-described engine low-speed start-up control or start-up control with the clutch 21 interlocked is represented by a broken line β. Here, the predetermined time B is experimentally obtained as the start control time that can prevent the oil from rising from the compressor, and is stored in the memory of the control means 30 as a map.

The refrigerant circuit figure of one Example which concerns on this invention. The graph which showed the change of the oil dilution with respect to elapsed time. The refrigerant circuit figure of the other Example which concerns on this invention. The graph which showed the pressure change at the time of the compressor starting with respect to elapsed time.

2 Compressor 19 Ventilation fan 21 Clutch 22 Engine 24 Temperature sensor 25 Heater 30 Control device 32 Setting device 43 Engine room

Claims (1)

In an engine-driven heat pump in which an engine and two compressors are housed in an engine room and a ventilation fan is provided in the engine room, only one compressor is driven during heating operation, and the engine room is below a predetermined temperature. In this case, by stopping the ventilation fan, the temperature in the engine room is increased by engine waste heat , and refrigerant stagnation of the stopped compressor is suppressed , and the compressor has an oil sump and no oil sump. An engine-driven heat pump characterized in that when the stop time of the two compressors exceeds a predetermined time, the compressor having the oil sump is driven first .

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