WO2004001304A1

WO2004001304A1 - Engine heat pump

Info

Publication number: WO2004001304A1
Application number: PCT/JP2003/007232
Authority: WO
Inventors: Jirou Fukudome
Original assignee: Yanmar Co., Ltd.
Priority date: 2002-06-20
Filing date: 2003-06-06
Publication date: 2003-12-31
Also published as: AU2003241975A1; JP2004020153A

Abstract

An engine heat pump, comprising a main compressor (2) driven by an engine, an indoor heat exchanger (8), an outdoor heat exchanger (5), an expansion valve (23) for the indoor heat exchanger, an expansion valve (21) for the outdoor heat exchanger, an engine waste heat recovery device (6) installed parallel with the outdoor heat exchanger, an expansion valve (22) for the engine waste heat recovery device, and an auxiliary compressor (3), wherein the auxiliary compressor compresses refrigerant passed through the engine waste heat recovery device at the time of heating and the refrigerant discharged from the auxiliary compressor is merged with refrigerant discharged from the main compressor, and the volumetric capacity of the auxiliary compressor is reduced less than that of the main compressor.

Description

Description Engine heat pump Technical field

The present invention relates to a device configuration of an engine heat pump, and more particularly, to a technique for minimizing a compression work of a compressor and improving energy efficiency in a full load region. Background art

In an engine heat pump, during heating, the refrigerant is compressed by a compressor and discharged as a high-temperature, high-pressure refrigerant gas, radiated by an indoor heat exchanger, and then expanded by an expansion valve so that the refrigerant temperature is lower than the outside air temperature. There is a heating cycle in which the temperature is lowered, the heat is absorbed by an outdoor heat exchanger, evaporated and vaporized, and then sucked into a compressor.

In this heating cycle, the outdoor heat exchanger evaporates the refrigerant by absorbing heat from the outside air and draws the low-temperature, low-pressure refrigerant gas into the compressor.The temperature of the refrigerant supplied to the outdoor heat exchanger is lower than the outside air temperature. As for the heat exchange. The compressor compresses the refrigerant again and discharges it as a high-temperature and high-pressure refrigerant gas.

Regarding the configuration of the engine heat pump that performs the heating cycle as described above, Japanese Patent Application Laid-Open No. 62-293630 discloses an outdoor heat exchanger that evaporates a refrigerant at an outside temperature, and an engine cooling water It discloses a configuration in which an engine waste heat recovery unit that evaporates by the heat of the air is provided in parallel. The outdoor heat exchanger and the engine waste heat recovery device respectively suck the evaporated refrigerant into separate compressors of the same capacity.

As described above, in the conventional engine heat pump equipped with two combinations of the heat exchanger and the compressor, the refrigerant is circulated to both the outdoor heat exchanger and the engine waste heat recovery unit in the normal heating operation state. On the other hand, in a low load operation state where the required heating capacity is low, the heating capacity can be set lower by circulating the coolant only in the outdoor heat exchanger without circulating the coolant in the engine waste heat recovery unit. As a result, the room temperature can be adjusted with low load operation by continuous operation, instead of intermittent operation that repeatedly starts and stops the engine. I'm trying.

The Mollier diagram (vertical axis: pressure, horizontal axis: specific enthalpy) of the heating cycle of the engine heat pump in the above configuration is as shown in Figure 16. In this conventional configuration, two heating cycles 10 and 20 are performed by two sets of the heat exchanger and the compressor. The term “compression work” refers to the ratio of the compression required by each compressor to increase the refrigerant pressure to the discharge pressure.

First, in the heating cycle 10, in the compression section AB, the compressor performs a compression work AW 1 on the refrigerant having a unit mass flow rate, and in the condensation section BC, heat is released by condensing the refrigerant in the indoor heat exchanger. In the expansion section CD, the refrigerant is expanded by the expansion valve to make the refrigerant liquid lower in pressure and temperature than the outside temperature line G, and in the evaporation section DA, the refrigerant is removed from the outside air by the outdoor heat exchanger. The refrigerant is evaporated by heat absorption.

Similarly, for the heating cycle 20, the refrigerant is evaporated by absorbing the exhaust heat of the engine in the engine waste heat recovery unit via the evaporation section EF, and the compression work 2 is performed by the compressor. .

However, in the above-described conventional engine heat pump, the only difference is whether the refrigerant is circulated to the engine waste heat recovery unit depending on the level of the load, and the compressors are operated in two different heating cycles 10 and 20 respectively. No study has been made on reducing the compression work AW 1 and AW 2 of the car.

This reduction in compression work AW 1 · Δ · 2 is directly linked to the reduction in fuel consumption of the engine that drives the compressor. The coefficient of performance during heating operation (heating capacity / (fuel consumption + electricity consumption) It is also important from the viewpoint of improving

Therefore, to study the reduction of the compression work AW1 · ΔΥ2 per unit mass flow rate, the outdoor work heat exchanger was used for the compression work AW1 in the heating cycle 10 of the refrigerant passing through the outdoor heat exchanger. Since the refrigerant must be kept at a lower temperature and lower pressure than the outside temperature line G because the refrigerant evaporates depending on the temperature, the heating cycle 10 cannot be changed and the compression work ZW 1 cannot be reduced. .

On the other hand, in the compression work 2 in the cooling heating cycle 20 via the engine waste heat recovery unit, the refrigerant is evaporated by the temperature of the engine cooling water. It is sufficient that EF is lower temperature and lower pressure than the engine coolant temperature line H. Therefore, it is conceivable to reduce the compression work AW2 by setting the line of the evaporation section EF to a higher position (increase the refrigerant pressure). However, the conventional engine heat pump has a volume capacity of a compressor that performs a heating cycle 20 passing through an engine waste heat recovery unit (a refrigerant suction volume (or discharge) per cycle (one revolution) of a rotating body provided in the compressor). Volume)) is the same as the volume capacity of the compressor that performs the heating cycle 10 that passes through the outdoor heat exchanger, and the refrigerant suction pressure of the compressor that performs the heating cycle 20 is reduced more than necessary. The EF line was moved away from the engine cooling water temperature line H, and sometimes tended to be lower than the outside temperature line G (evaporation section E 'F'). Disclosure of the invention

An object of the present invention is to focus on the volume capacity of each compressor corresponding to an outdoor heat exchanger and an engine waste heat recovery device, and to maintain the refrigerant suction pressure in the compressor as high as possible. To reduce the work of compressing the refrigerant due to the pressure.

In order to achieve this object, the present invention provides a main compressor driven by an engine, an indoor heat exchanger, an outdoor heat exchanger, an expansion valve for an indoor heat exchanger, an expansion valve for an outdoor heat exchanger, and an outdoor heat exchanger. An engine waste heat recovery unit, an expansion valve for the engine waste heat recovery unit, and an auxiliary compressor are provided in parallel, and the auxiliary compressor compresses the refrigerant that has passed through the engine waste heat recovery unit during heating. In an engine heat pump configured to combine refrigerant discharged from the auxiliary compressor with refrigerant discharged from the main compressor, the volume capacity of the auxiliary compressor is smaller than that of the main compressor.

Thus, in accordance with the auxiliary compressor having a reduced volumetric capacity, the evaporation pressure in the engine waste heat exchanger is maintained at a higher pressure than when evaporating at ambient temperature, and the compression work in the auxiliary compressor is reduced. However, the total compression work can be reduced as compared with the case where the whole amount is evaporated at the outside temperature and compressed, contributing to energy saving. The auxiliary compressor with a reduced volume capacity can be configured smaller than that of the main compressor, and it is easy to secure the installation space inside the package of the engine heat pump. It is also possible to increase the number of auxiliary compressors and to configure them.

In the engine heat pump, the auxiliary compressor may have a volume capacity of the main compressor. And a predetermined ratio of the total capacity of the auxiliary compressor.

As a result, the main compressor performs compression work for the majority of the circulating refrigerant amount, and prevents a decrease in the suction pressure of the refrigerant to the auxiliary compressor, thereby reducing the compression work by the auxiliary compressor. And the driving power (kW) can be reduced.

In the engine heat pump, the difference between the suction pressure of the auxiliary compressor and the discharge pressure of the main compressor is kept within a predetermined range.

As a result, the compression work of the auxiliary compressor is suppressed, and the compression work of the entire engine heat pump can be reduced.

In the engine heat pump, the main compressor and the suction line of the auxiliary compressor are connected by an on-off valve.

As a result, both compressors can draw in refrigerant from the outdoor heat exchanger and the engine waste heat recovery unit, so that the outdoor heat exchanger and the engine waste heat recovery unit can be used even when performing heating operation with either compressor alone. Can be used as evaporator. An auxiliary compressor can be used even during cooling.

Further, in the engine heat pump, the auxiliary compressor is driven by an electric motor.

As a result, the degree of freedom of the layout of the auxiliary compressor in the outdoor unit is wide, and the controller can control the rotation speed and the compression ratio of the auxiliary compressor alone independently of the main compressor.

In addition, in the engine heat pump, at the time of heating and at a low load, the auxiliary compressor of the two compressors is operated alone and the outdoor heat exchanger of the two heat exchangers is operated alone. Of the two compressors, the main compressor is operated independently, and the outdoor heat exchanger and the engine waste heat recovery unit are operated. At high load, both the compressors are operated and the outdoor heat exchanger and the engine waste heat recovery unit are operated. Activate the collector.

This enables optimal operation according to the load, improves energy efficiency, and responds to demands for high heating capacity.

Further, in the engine heat pump, at the time of startup, the auxiliary compressor alone is operated among the two compressors.

This prevents liquid refrigerant from being drawn into the main compressor during startup. Can be. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a refrigerant circuit diagram of the engine heat pump of the present invention.

FIG. 2 is a block diagram of control devices for an engine heat pump.

FIG. 3 is a Mollier diagram of a heating cycle of the engine heat pump according to the configuration of the present invention.

FIG. 4 is a graph showing the relationship between the volumetric capacity ratio of the auxiliary compressor and the driving power / refrigerant evaporation pressure.

FIG. 5 is a table showing an example of a numerical combination of a volume capacity ratio and a volume capacity.

FIG. 6 is a flowchart when the refrigerant temperature is adjusted by controlling the opening of the expansion valve.

FIG. 7 is a flow chart when the refrigerant pressure is adjusted by controlling the opening of the B-Peng Zhang valve and controlling the rotation speed of the compressor.

FIG. 8 is a refrigerant circuit diagram showing a refrigerant flow when the air conditioning load during heating is low.

FIG. 9 is a refrigerant circuit diagram when the air conditioning load is a medium load during heating.

FIG. 10 is a refrigerant circuit diagram when the air conditioning load is high during heating. FIG. 11 is a refrigerant circuit diagram showing a refrigerant flow when the air-conditioning load during cooling is a low / medium load.

FIG. 12 is a refrigerant circuit diagram when the air conditioning load during cooling is high. FIG. 13 is a graph showing the level of the air conditioning load according to the present invention.

FIG. 14 is a refrigerant circuit diagram showing a refrigerant flow in a pumping operation.

FIG. 15 is a graph showing the relationship between the operation time and the auxiliary compressor and engine speed in the pumping operation.

FIG. 16 is a Mollier diagram of a heating cycle of an engine heat pump in a conventional configuration. BEST MODE FOR CARRYING OUT THE INVENTION

The outdoor unit 1 shown in Fig. 1 is installed outside a room that requires air conditioning, and has a main compressor 2, an auxiliary compressor 3, an engine 4, an outdoor heat exchanger 5, and an outdoor heat exchanger. The engine is equipped with an engine waste heat recovery device 6 and the like provided in parallel with 5.

The main compressor 2 is configured to drive an internal rotating body by an engine 4. On the other hand, the auxiliary compressor 3 supplies a commercial power supply 40 to the electric motor, and drives the internal rotating body by the electric motor. That is, the auxiliary compressor 3 is configured as an electric compressor, and has a layout in an outdoor unit. The degree of freedom is high.

On the other hand, the indoor unit 7 is installed in a room requiring air conditioning, and includes an indoor heat exchanger 8 and the like. Although not shown, a plurality of indoor units 7 may be provided.

Then, the outdoor unit 1 and the indoor unit 7 are connected by the refrigerant line 9, the refrigerant is circulated in the refrigerant line 9, and the flow direction is changed by the four-way valve 24. Or a heating cycle.

In the refrigerant line 9, an expansion valve 21 for an outdoor heat exchanger, an expansion valve 22 for an engine waste heat recovery unit, and an expansion valve 2 for an indoor heat exchanger Three are provided.

In the refrigerant line 9, a supply pipe 20a is connected to the discharge port 2a of the main compressor 2, and a supply pipe 30a is connected to the discharge port 3a of the auxiliary compressor 3. The other side of the supply pipe 30a is connected to a connection point 35 upstream of the four-way valve 24 of the supply pipe 20a. As a result, the refrigerant discharged from the main compressor 2 and the auxiliary compressor 3 merges and is supplied to the indoor unit 7 via the four-way valve 24 during heating.

Further, in the refrigerant line 9, the four-way valve 24 and the suction port 2b of the main compressor 2 are connected by a return pipe 2Ob, and the port on the outlet side of the engine waste heat recovery unit 6 is connected to an auxiliary port. The suction port 3 b of the compressor 3 is connected by a return pipe 3 Ob, and the two return pipes 20 b · 30 b are connected by a bypass pipe 33 provided with an electromagnetic on-off valve 34. Further, the engine 4 and the engine waste heat recovery unit 6 are connected by a cooling water pipe 14, and the exhaust heat of the engine 4 is transmitted to the refrigerant passing through the engine waste heat recovery unit 6. And In the cooling water pipe 10, reference numeral 11 denotes a thermostat, and reference numeral 12 denotes a cooling water pump.

FIG. 2 shows a configuration of a detection device, a control device, and the like for controlling the operation of the engine heat pump of the present invention. The controller 25, which is a control device, has a temperature sensor 41 that detects the refrigerant temperature difference at the entrance and exit of the outdoor heat exchanger 5, a temperature sensor 42 that detects the refrigerant temperature difference at the entrance and exit of the engine waste heat recovery unit 6, and the room Temperature sensor 43 for detecting the refrigerant temperature difference at the entrance and exit of the heat exchanger 8, thermostat 11 1, pressure sensor 51 for detecting the discharge pressure of the main compressor 2, pressure sensor for detecting the suction pressure of the auxiliary compressor 3. One and two are connected. The controller 25 opens the expansion valve 21 for the outdoor heat exchanger, the expansion valve 22 for the engine waste heat recovery unit, the expansion valve 23 for the indoor heat exchanger, and the solenoid on-off valve 3 4 based on the detection results of these detection devices. Adjust the degree. Further, the controller 25 also controls the start and stop of the engine 4 (main compressor 2) and the auxiliary compressor 3.

Since the auxiliary compressor 3 is driven by an electric motor, it does not require direct power supply from the engine, and the controller 25 controls the rotation speed of the auxiliary compressor 3 independently of the main compressor 2 · The compression ratio can be controlled.

A heating cycle performed by the engine heat pump configured as described above will be described. As shown in FIG. 1, the refrigerant compressed by the main compressor 2 and the auxiliary compressor 3 joins at the connection point 35, is sent to the indoor heat exchanger 8 via the four-way valve 24, and After being radiated and condensed by the heat exchanger 8, it is expanded by the expansion valve 21 for the outdoor heat exchanger and the expansion valve 22 for the engine waste heat recovery unit, and absorbed by the outdoor heat exchanger 5 and the engine waste heat recovery unit 6, respectively. After being evaporated and evaporated, it is sucked by the main compressor 2 and the auxiliary compressor 3, and is compressed by these compressors 2 and 3 and then discharged again.

Explaining the cooling cycle, the refrigerant compressed by the main compressor 2 and the auxiliary compressor 3 joins at the connection point 35, and is sent to the outdoor heat exchanger 5 via the four-way valve 24. After being radiated and condensed by the outdoor heat exchanger 5, the heat is condensed by the indoor heat exchanger expansion valve 23, absorbed by the indoor heat exchanger 8 and evaporated, and then the main compressor 2 or the bypass It is sucked into the auxiliary compressor 3 through the pipe 33 and compressed by these compressors 2 and 3. After that, the cycle of discharging again is repeated.

Next, the relationship between the volume capacities of the main compressor 2 and the auxiliary compressor 3 in the engine heat pump configured as described above will be described.

In the engine heat pump of the present invention, the volumetric capacity V3 of the auxiliary compressor 3 as shown in the table of FIG. 5 is smaller than the volumetric capacity V2 of the main compressor 2, and the refrigerant suction pressure P of the auxiliary compressor 3 3 to reduce the compression work AW2 (Fig. 3). As a result, during heating, as shown in the Mollier diagram shown in Fig. 3, the evaporating section EF can be set at a high pressure position to reduce the compression work AW2 (narrow the width of the compression work Δ "\ ¥ 2). You can.

In other words, by maintaining the evaporation pressure at a higher pressure than when evaporating a part of the refrigerant at ambient temperature and reducing the compression work AW2 of the refrigerant, it is possible to evaporate the entire amount at ambient temperature and compress it. Thus, the total compression work (AW1 + AW2) can be reduced.

The volume capacity V2'V3 here is the refrigerant suction volume (ccZ cycle) per one cycle (rotation) of the rotating body provided in each of the compressors 2 and 3.

The preferred volume capacity for reducing this compression work AW2 is the volume capacity ratio E (%), that is, the total volume capacity V 2 of the main compressor 2 and the volume capacity V 3 of the auxiliary compressor 3 The ratio can be determined based on the ratio of the volume capacity V3 of the auxiliary compressor 3 to the product capacity.

CE (%) = V3 / (V2 + V3) X 100

In the graph of Fig. 4, the horizontal axis represents the volume capacity ratio E (%), the left vertical axis represents the driving power (kW) of the auxiliary compressor 3, and the right vertical axis represents the refrigerant evaporation pressure (MPa). %) As 50, 25, 10, and 8, the driving power (kW) of the auxiliary compressor 3 and the refrigerant evaporation pressure P 6 of the engine waste heat recovery unit 6 and the outdoor heat exchanger 5 respectively. It shows the measurement result of P 5 (MPa).

For comparison, the refrigerant evaporation pressures P 6 and P 5 (MPa) in the case of an engine heat pump without the auxiliary compressor 3 are also shown.

The table in Fig. 5 shows one of the combinations of the values of the volume capacity V 2 · V 3 (c cZ cycle) of the main compressor 2 and the auxiliary compressor 3 corresponding to the volume capacity ratio () in the above graph. This shows an example, and also shows the ratio of the corresponding refrigerant mass flow rate F1 (kg / min) of the main compressor 2 and the corresponding refrigerant mass flow rate F2 (kg / min) of the auxiliary compressor 3. I have.

Explaining the graph of FIG. 4, the driving power (kW) (bar graph) of the auxiliary compressor 3 rapidly decreases when the volume capacity ratio E (%) is changed from 50% to 25%, and the volume capacity ratio E ( %) To 10%. When the volumetric capacity ratio E (%) is set to 10% or less, the suction pressure P 3 of the auxiliary compressor 3 becomes excessive, and the difference between the discharge pressure and the suction pressure becomes extremely small. The compression stroke at does not hold.

The fluctuation in the driving power (kW) of the auxiliary compressor 3 follows that the refrigerant evaporation pressure P 6 (MPa) in the engine waste heat recovery unit 6 is increasing, and the volume capacity ratio E (%) Is in the range of 10% to 25%, the main compressor 2 performs the compression work AW1 for the majority of the circulating refrigerant amount, and the refrigerant evaporation pressure P 6 (MPa) is high, and the auxiliary compressor Since the suction pressure P3 of 3 is high, the evaporating section EF shown in Fig. 3 increases, the compression work 2 is reduced, and the driving power (kW) is reduced.

On the other hand, when the volumetric capacity ratio E (%) is further reduced from 10%, the refrigerant evaporation pressure P 6 (MPa) becomes excessively large, and the compression process in the auxiliary compressor 3 cannot be realized. From the above relationship, by setting the volumetric capacity ratio E (%) from 10% to 25%, a decrease in the suction pressure P3 of the refrigerant into the auxiliary compressor 3 is prevented, and the compression work AW2 is reduced. It can be said that the driving power (kW) can be reduced. An example in which the volume capacity ratio E (%) is set to 10% to 25% is one of the preferred embodiments, and the volume capacity ratio E (%) is set to a predetermined ratio suitable for each device configuration. Doing so does not depart from the inventive concept.

Further, in the above configuration, the volume capacity V 3 of the auxiliary compressor 3 is set smaller than the volume capacity V 2 of the main compressor 2, and the device can be configured to be small. Since it is easy to secure the installation space inside the facility, it is possible to add and configure the existing equipment design.

Next, a configuration for reducing the compression work AW1 and AW2 by controlling the opening degrees of the outdoor heat exchanger expansion valve 21 and the engine waste heat recovery unit expansion valve 22 will be described. This configuration is the configuration shown in FIG. 1, in which the temperature of the secondary side is detected by the temperature sensor 41 in the flow of the refrigerant in the outdoor heat exchanger 5 during heating, and the engine waste heat recovery unit 6 The temperature on the downstream side is detected by the temperature sensor 42, and the detection results are recognized by the controller 25.The controller 25 controls the expansion valve 21 for the outdoor heat exchanger and the expansion valve for the engine waste heat recovery unit. By controlling the opening of 22, the suction pressure of the main compressor 2 and the auxiliary compressor 3 is adjusted, and the compression work AW 1 · AW 2 (FIG. 3) is reduced.

In the above configuration, the controller 25 as shown in the flowchart of FIG. 6 includes a refrigerant temperature Δ Τ 1 (° C.) at the entrance and exit of the outdoor heat exchanger 5 and a refrigerant temperature difference Δ Τ at the entrance and exit of the engine waste heat recovery unit 6. 2 (° C), and when the refrigerant temperature differences Δ Τ 1 and Δ Τ 2 (° C) are each a predetermined positive value, it is recognized that the refrigerant is evaporating, and the refrigerant temperature As long as the difference Δ Δ 1 ΔΔ CC 2 CC) maintains a predetermined positive value, the degree of opening of the expansion valve 21 for the outdoor heat exchanger and the expansion valve 22 for the engine waste heat recovery unit is increased, and the refrigerant pressure is increased. It is to prevent the decrease.

In other words, the opening of the expansion valve 21 for the outdoor heat exchanger and the expansion valve 22 for the engine waste heat recovery unit are not made unnecessarily small, so that the refrigerant can evaporate. The pressure of the refrigerant is prevented from dropping as far as it does not occur. Then, in the present embodiment, a predetermined value α (> 0) (° C) is set in order to prevent a liquid back.

In this way, the suction pressure of the refrigerant of the main compressor 2 and the auxiliary compressor 3 can be adjusted, the suction pressure can be kept as high as possible, and the compression work AW 1 · AW 2 can be reduced.

Further, in addition to the above configuration, at the time of heating, the discharge pressure P 2 of the main compressor 2 is detected by the pressure sensor 51, and the suction pressure P 3 of the auxiliary compressor 3 is similarly detected by the pressure sensor 152. The controller 25 recognizes these detection results, and the controller 25 sets the discharge pressure P 2 and sets the rotation speed R of the main compressor 2 in order to exhibit the desired air-conditioning capacity. By controlling the rotation speed R 2 of the auxiliary compressor 3 while controlling the pressure 1, the pressure difference Δ の between the suction pressure P 3 and the discharge pressure P 2 is kept within a predetermined range.

The predetermined range of the pressure difference Δ いう here means that the compression process in the auxiliary compressor 3 It is a range that is greater than or equal to the minimum value that holds, and is near the minimum value.

In the above configuration, as shown in the flowchart of FIG. 7, when the pressure difference ΔΡ is within a predetermined range, that is, when the pressure difference Δ 差 is smaller than the target value, the suction pressure P 3 is high, and the auxiliary compressor 3 has a small compression work. △ Since energy-efficient operation by W2 is possible, increasing the rotation speed of the auxiliary compressor 3 and increasing the refrigerant suction amount of the auxiliary compressor 3 allows more refrigerant to increase energy efficiency. Compression can be performed with good operation (Step 701).

On the other hand, when the pressure difference Δ より is larger than the target value, the suction pressure P 3 is low, and the auxiliary compressor 3 is in a state where the operation with low energy efficiency is performed by the large compression work AW 2. By reducing the number of revolutions of the compressor 3 and reducing the refrigerant suction amount of the auxiliary compressor 3, the auxiliary compressor 3 is prevented from operating with poor energy efficiency (step 720).

On the other hand, when the pressure difference Δ 一致 matches the target value, the state is on the boundary of whether or not the energy efficiency is good, so that the rotation speed of the auxiliary compressor 3 is maintained.

Then, while maintaining the rotation speed of the auxiliary compressor 3, the pressure in the condensation section BC in the Mollier diagram (FIG. 3), that is, the P2 target value, is compared (Step 70). 3) If the discharge pressure P 2 is smaller than the target value P 2, the number of revolutions R 1 of the main compressor 2 is increased, and the discharge pressure P 2 is increased to the pressure of the condensing section BC to cool the air. On the other hand, if the discharge pressure P 2 is larger than the target value P 2, energy wasted due to excessive compression in the main compressor 2 should be prevented. The number of revolutions R1 of 2 is decreased (step 705).

In this way, the compression work of the auxiliary compressor 3 can be suppressed and the compression work of the entire engine heat pump can be reduced while exhibiting the desired air conditioning capacity as the engine heat pump.

Next, in the configuration of the engine heat pump described above, energy efficiency is improved by controlling the operation of the main compressor 2 and the auxiliary compressor 3 according to the size of the air conditioning load, and the control of the opening and closing of the solenoid on-off valve 34. The configuration to be achieved will be described.

As shown in FIGS. 8 to 10, this control is performed during heating, when the air conditioning load is low, the auxiliary compressor 3 of both compressors is operated alone, Of these compressors, the outdoor heat exchanger operates independently.At medium loads, the main compressor of both compressors operates independently, and the outdoor heat exchanger and the engine waste heat recovery unit operate at high loads. The unit is operated and the outdoor heat exchanger and the engine waste heat recovery unit are operated. On the other hand, during cooling, as shown in Fig. 11, when the air-conditioning load is low to medium, the auxiliary compressor operates independently and the outdoor heat exchanger operates independently. Operate the unit and operate the outdoor heat exchanger independently.

As shown in Fig. 13, the level of the air conditioning load mentioned above generally ranges from 0% to 15% when the air conditioning load (%) of the engine heat pump is low, and from 15% to 60%. Is treated as medium load, and the range from 60% to 100% is treated as high load.

For the above configuration, first, the operation during heating will be described in detail. When the air conditioning load is low, as shown in Fig. 8, the controller 25 completely stops the expansion valve 22 for the engine waste heat recovery unit. At the same time, the solenoid on-off valve 3 4 is opened, and the engine 4 and the main compressor 2 are stopped, while the auxiliary compressor 3 is driven, so that the refrigerant absorbs heat in the outdoor heat exchanger 5 and evaporates. After that, it is sucked into the auxiliary compressor 3 through the bypass pipe 33, compressed and discharged by the auxiliary compressor 3, radiates heat in the indoor heat exchanger 8, and condenses. As described above, in low load operation with a low required heating capacity, a small amount of compression work is performed only by the auxiliary compressor 3, so that compared to the case where the engine 4 is driven to operate the main compressor 2, Energy-efficient heating operation can be performed. During heating, when the air conditioning load is medium, as shown in Fig. 9, the controller 25 opens the expansion valve 22 for the engine waste heat recovery unit and the solenoid on-off valve 34, and furthermore, the engine 4 To start the main compressor 2 and stop the auxiliary compressor 3, the refrigerant absorbs heat in both the outdoor heat exchanger 5 and the engine waste heat recovery unit 6 and evaporates. After that, the refrigerant that has passed through the outdoor heat exchanger 5 is drawn into the main compressor 2, and similarly, the refrigerant that passed through the engine waste heat recovery unit 6 is drawn into the main compressor 2 through the bypass pipe 33, and The air is compressed and discharged by the main compressor 2, and is discharged and condensed in the indoor heat exchanger 8. As described above, in the medium load operation in which the required heating capacity is intermediate, the compression work of the maximum capacity is performed from the middle in the main compressor 2 only by the main compressor 2 without driving the auxiliary compressor 3. In addition, the main compressor 2 can perform an energy-efficient heating operation. During heating, when the air-conditioning load is high, as shown in Fig. 10, the controller 25 opens the engine waste heat recovery unit expansion valve 22 and completely closes the solenoid on-off valve 34. When the engine 4 is started to drive the main compressor 2 and the auxiliary compressor 3 is driven, the refrigerant absorbed and evaporated in the outdoor heat exchanger 5 is transferred to the main compressor 2 and the engine waste heat The refrigerant that has absorbed heat in the recovery unit 6 and evaporated evaporates into the auxiliary compressor 3, passes through independent flow paths, and is sucked into separate compressors. After being compressed and discharged, and joined at the connection point 35, the heat is radiated and condensed by the indoor heat exchanger 8. As described above, in a high-load operation with a high required heating capacity, both the main compressor 2 and the auxiliary compressor 3 are driven to perform a large-capacity compression work so that it is possible to meet a demand for a high heating capacity. I have.

When both the main compressor 2 and the auxiliary compressor 3 are driven as described above, the opening degrees of the outdoor heat exchanger expansion valve 21 and the engine waste heat recovery expansion valve 22 described above must be adjusted. By doing so, compression work AW 1.2 can be reduced.

On the other hand, as for the operation during cooling, as shown in Fig. 11, when the air-conditioning load is low to medium, the controller 25 completes the expansion valve 22 for engine waste heat recovery unit and the solenoid on-off valve 34. When the auxiliary compressor 3 is stopped and the engine 4 and the main compressor 2 are driven, the refrigerant dissipates heat in the outdoor heat exchanger 5 and condenses, and then expands for the indoor heat exchanger. It is expanded by the valve 23, absorbed and evaporated in the indoor heat exchanger 8, sucked into the main compressor 2, compressed by the main compressor 2 and discharged. As described above, in the operation from low load power to middle load where the required cooling capacity is low or intermediate, energy-efficient cooling operation is performed only with the main compressor 2 without driving the auxiliary compressor 3. be able to.

At the time of cooling, when the load is high, as shown in FIG. 12, the controller 25 opens the solenoid on-off valve 34 from the operation state between the low load and the medium load, and sets the auxiliary compressor 3 Then, the auxiliary compressor 3 compensates for the compression work of the main compressor 2, and both compressors perform large-capacity compression work. In this way, by supplying the refrigerant to the auxiliary compressor 3 and performing the compression work, it is possible to meet the demand for a high required cooling capacity.

Next, the pumping operation performed by the engine heat pump with the above configuration is explained. I will tell.

In the pumping operation, the main compressor is used for a predetermined time when the engine heat pump is started.

By operating the auxiliary compressor 3 alone and operating independently while keeping the 2 stopped, the auxiliary compressor alone is operated, and the residual liquid refrigerant in the outdoor heat exchanger 5 or the engine waste heat recovery device 6 is pumped up. When the main compressor 2 is started, the suction of the residual liquid soot into the main compressor 2 is prevented.

The pumping operation is performed during both heating and cooling. When the pumping operation is described, as shown in FIGS. 14 and 15, the controller 25 generates the outdoor heat. While the expansion valve 21 for the exchanger and the expansion valve 22 for the engine waste heat recovery unit are completely closed, the expansion valve 23 for the indoor heat exchanger is fully opened, and the electromagnetic switching valve 34 is fully opened. Then, without starting the engine 4, the start of the auxiliary compressor 3 is started, and the residual liquid refrigerant in the outdoor heat exchanger 5 and the engine waste heat recovery unit 6 is sucked, that is, pumped.

The time for which the auxiliary compressor 3 is operated independently can be set arbitrarily.

(In this embodiment, it is two minutes (Fig. 15).) After that, the engine 4 is started, the main compressor 2 and the auxiliary compressor 3 are operated together, and then the auxiliary compressor 3 is stopped. Then, only the main compressor 2 is operated. Then, a predetermined time (in this embodiment, four minutes) from the start of the independent operation of the auxiliary compressor 3 to the stop of the auxiliary compressor 3 is set as a pumping operation, and is executed when the engine heat pump is started. When the main compressor 2 is started, the suction of the residual liquid refrigerant into the main compressor 2 can be prevented. Industrial applicability

By applying the above configuration to the engine heat pump, the compression work of the compressor can be minimized, and the energy efficiency can be improved over the entire load range.

Claims

Scope of request Main compressor driven (2), indoor heat exchanger (8), outdoor heat exchanger (5), expansion valve for indoor heat exchanger (23), expansion valve for outdoor heat exchanger (2) 1), an engine waste heat recovery unit (6), an expansion valve for an engine waste heat recovery unit (22), and an auxiliary compressor (3) provided in parallel with the outdoor heat exchanger. An engine heat pump configured to compress the refrigerant that has passed through the engine waste heat recovery unit during heating, and to combine the refrigerant discharged from the auxiliary compressor with the refrigerant discharged from the main compressor. An engine heat pump wherein the volume capacity of the auxiliary compressor is smaller than that of the main compressor.

2. The engine heat pump according to claim 1, wherein the volume capacity of the auxiliary compressor is a predetermined ratio of the total capacity of the main compressor and the auxiliary compressor.

3. The engine heat pump according to claim 2, wherein a difference between a suction pressure of the auxiliary compressor and a discharge pressure of the main compressor falls within a predetermined range.

4. The engine heat according to claim 2, wherein the suction line of the main compressor and the suction line of the auxiliary compressor can be communicated via an on-off valve (34). pump.

5. The engine heat pump according to claim 2, wherein the auxiliary compressor is driven by an electric motor.

6. During heating, when the load is low, the auxiliary compressor among the two compressors is operated alone, and the outdoor heat exchanger among the heat exchangers is operated alone. Among the compressors, the main compressor alone is operated and the outdoor heat exchanger and the engine waste heat recovery unit are operated. At a high load, both the compressors are operated and the outdoor heat exchanger and the Claim 5 characterized by operating the engine waste heat recovery unit The described engine heat pump.

7. The engine heat pump according to claim 5, wherein at the time of starting, the auxiliary compressor is operated independently of the two compressors.