JPH11230646A - Engine driven heat pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable continuous heating and defrosting by using a plurality of compressors and prevent heating efficiency from decreasing during the continuous heating and defrosting due to piping resistance and the like on an indoor heat exchanger side resulting from an increase in the number of stories of a building and the like. SOLUTION: A refrigeration cycle wherein cooling and heating are switched by switching a four-way valve 4 is provided with a plurality of compressors 2a and 2b. This refrigeration cycle separately forms during defrosting a defrosting circuit for introducing a discharged refrigerant of one compressor 2a to an outdoor heat exchanger 7 by means of a first defrosting bypass circuit 21 and a heating circuit for introducing a discharged refrigerant of the other compressor 2b into an indoor heat exchanger 5 to be returned by a second defrosting bypass circuit 22. According to this arrangement, defrosting and heating are performed and a heating effect is improved independently of the intensity of piping resistance of the indoor heat exchanger 5 side due to an increase in the number of stories of a building and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to defrosting during a heating operation in an engine driven heat pump.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 6-265242 discloses a technique for performing defrosting during a heating operation using an engine-driven heat pump.
The technology disclosed in Japanese Patent Laid-Open Publication No. H10-26095 is known. This technology is
When defrosting frost on the outdoor heat exchanger during the heating operation, defrosting is performed without stopping indoor heating by the indoor heat exchanger, and two refrigerants discharged from one compressor are used. This is a technique in which one of the branched refrigerants is guided to an outdoor heat exchanger to perform defrosting, and the other branched refrigerant is guided to an indoor heat exchanger for heating. The refrigerant that has passed through the heat exchanger is heated by the refrigerant heater and then returned to the compressor.

[0003]

As shown in FIG. 4, a two-compartment compressor employing a plurality of compressors 2a and 2b for the purpose of achieving both high performance and energy saving as well as employing the above-described continuous heating and defrosting technology. There is a one-cycle engine driven heat pump. However, in recent years, the length of the pipes on the indoor heat exchanger 5 side tends to be long, and the height difference tends to be large due to the rise of buildings and the like. Due to these tendencies, the pipe resistance on the indoor heat exchanger 5 side increases, and in the case of continuous heating and defrosting, the first defrost bypass circuit 21 with a small pipe resistance (refrigerant circulation circuit to the outdoor heat exchanger 7). A large amount of refrigerant flows to the second defrost bypass circuit 22 (the indoor heat exchanger 5) having a large pipe resistance.
The amount of the refrigerant circulating to the refrigerant circuit decreases, and the heating effect at the time of continuous heating and defrosting is reduced.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to enable continuous heating and defrosting by using a plurality of compressors, and to improve piping resistance and the like during continuous heating and defrosting. An object of the present invention is to provide an engine-driven heat pump that does not have a problem that the heating effect is weakened by the heat.

[0005]

The engine driven heat pump of the present invention employs the following technical means. [Means of Claim 1] By doing as in Claim 1,
During continuous heating and defrosting, the high-temperature and high-pressure gas refrigerant discharged from one of the compressors directly flows into the outdoor heat exchanger via the first defrost bypass circuit, so that the frost adhering to the outdoor heat exchanger is removed. Is melted in a short time by the heat radiation of the high-temperature refrigerant.

At this time, the high-temperature and high-pressure gas refrigerant discharged from the other compressor flows directly into the indoor heat exchanger and radiates heat in the indoor heat exchanger, so that continuous heating during defrosting is effectively performed. Will be The refrigerant radiated by the indoor heat exchanger is
After merging with the refrigerant radiated by the outdoor heat exchanger through the second defrost bypass circuit, the refrigerant is heated by the refrigerant heater and returned to the plurality of compressors, so that the high-temperature and high-pressure gas refrigerant is always discharged from the plurality of compressors. it can.

As described above, the defrost circuit by one compressor (the circuit that passes through the first defrost bypass circuit and the outdoor heat exchanger)
And a heating circuit by the other compressor (the indoor heat exchanger and the second
(A circuit that passes through the defrost bypass circuit) is formed separately, so even if the length of the piping on the indoor heat exchanger side becomes long or the height difference becomes large due to the rise of buildings, indoor heat exchange The defrosting operation and the heating operation are performed simultaneously regardless of the magnitude of the pipe resistance on the vessel side. That is, according to the present invention, continuous heating defrosting can be performed using a plurality of compressors, and there is no problem that the heating effect is weakened by pipe resistance or the like during continuous heating defrosting.

[0008] According to the second aspect of the present invention, the plurality of compressors are operated and the engine is operated at a high rotational speed, so that the outdoor heat exchanger and the indoor heat exchanger can be operated. The amount of heat supplied increases. At this time, by operating the blower fan for indoor heating at a low rotation speed, the amount of refrigerant radiated in the room can be suppressed and used for defrosting, so that the defrosting time can be shortened. Further, by stopping the blower fan of the outdoor unit, it is possible to prevent the refrigerant flowing through the outdoor heat exchanger from being released by means other than the defrost due to the low-temperature outdoor airflow, thereby reducing the defrosting time. That is, by adopting this claim 2, a decrease in the heating capacity is suppressed,
In addition, there is an effect of reducing the defrosting time.

[0009]

Next, embodiments of the present invention will be described based on examples and modifications. 1 to 3 are drawings for explaining an embodiment employing the present invention, and FIG. 1 is a refrigerant circuit diagram showing a configuration of an engine driven heat pump.

First, the overall configuration will be described with reference to FIG. A plurality of compressors 2a driven by the engine 1,
2b (one compressor 2a and the other compressor 2b), an oil separator 3 for separating oil in the refrigerant, a four-way valve 4 for switching the flow path of the refrigerant discharged from the plurality of compressors 2a, 2b, The indoor heat exchanger 5 which functions as an evaporator and functions as a condenser during heating, the decompression device on the side of the indoor heat exchanger 5 (hereinafter referred to as the indoor decompression device 6), functions as a condenser during cooling and functions as an evaporator during heating. The outdoor heat exchanger 7, a decompression device (hereinafter referred to as an outdoor decompression device 8) on the side of the outdoor heat exchanger 7, a refrigerant heater 9 for heating the refrigerant with cooling water (warm water) of the engine 1, and a gas-liquid separation of the refrigerant. Accumulator 1 for extracting gas refrigerant
0 are connected by a refrigerant pipe to form a basic refrigeration cycle. The one compressor 2a and the other compressor 2b are each provided with a check valve B1
, B2 downstream.

In the above-described refrigeration cycle, one of the compressors 2
a first defrost bypass circuit 21 which is branched from the outdoor side pressure reducing device 8 and the outdoor heat exchanger 7 and is branched off from the discharge side of a and the point A on the upstream side of the check valve B1. ing. The first defrosting bypass circuit 21 is provided with a first defrosting solenoid valve 11 (first on-off valve) that opens the circuit 21 by energization.
Is provided.

In the above refrigeration cycle, a second defrost bypass connected to a point B between the outdoor heat exchanger 7 and the refrigerant heater 9 separated from the downstream side of the indoor decompression device 6. A circuit 22 is provided. The second defrost bypass circuit 22 includes a second defrost solenoid valve 12 (second on-off valve) that opens when the circuit 22 is energized, an auxiliary pressure reducing device 13, and refrigerant from the outdoor heat exchanger 7. A check valve 14 for preventing the inflow of the fluid is provided. Note that reference numeral 15 in FIG. 1 denotes an indoor fan (blower fan of the indoor heat exchanger 5), and reference numeral 16 denotes an indoor fan.
Is an outdoor fan (blower fan of the outdoor heat exchanger 7).

On the other hand, the circulation circuit of the engine coolant flows from the engine 1 through a thermostat 17 to a radiator 18.
And a circuit returning to the engine 1 through the refrigerant heater 9 through the thermostat 17 from the engine 1.
And a circuit returning to

FIG. 2 is an electric circuit diagram for executing the cooling, heating, and defrosting operation modes in the engine driven heat pump. This electric circuit controls the energization of the four-way valve 4, the first defrosting solenoid valve 11, the second defrosting solenoid valve 12, the indoor fan 15, and the outdoor fan 16 provided in the refrigeration cycle, and performs each operation mode. The main switch 31 is connected to and disconnected from the power supply D. Four-way valve 4, first defrosting solenoid valve 11, second defrosting solenoid valve 12,
Each of the indoor fan 15 and the outdoor fan 16 is connected to the main switch 31 via relay contacts r1 to r5 connected in parallel, and each of the relay contacts r1 to r5 has five relays controlled by the control circuit 30. R1 to R5
Is opened and closed by The control circuit 30 is connected to a main switch 31 via a changeover switch 32 having a cooling contact C and a heating contact H, and detects a switching state of the changeover switch 32 and a frost that detects frost formation on the outdoor heat exchanger 7. According to the detection output of the sensor 33, the above five relays R
1 to R5 are energized.

[Operation of the Embodiment] When the main switch 31 is turned on, an electromagnetic clutch (not shown) is used according to the air conditioning load.
Operates to start the operation of the refrigeration cycle. When the air conditioning load is small, one compressor 2a and the other compressor 2a
When the air conditioning load is large, one compressor 2a and the other compressor 2b operate simultaneously, and the simultaneous operation will be described as an example.

<Heating operation> In a state where the changeover switch 32 is set to the heating contact H and the frost sensor 33 does not detect frost on the outdoor heat exchanger 7, the control circuit 30
Turns on the relays R1, R4, R5 and relays R2, R3
Is not energized. Thereby, the relay contacts r1, r4, r
5 is closed and the relay contacts r2 and r3 are opened. As a result, the four-way valve 4 is switched to the heating side, the first and second solenoid valves 11 and 12 for defrosting are closed, and the indoor fan 15 and the outdoor fan 16 operate at the normal rotation speed.

Explaining the flow of the refrigerant during the heating operation, the high-temperature and high-pressure refrigerant discharged from the plurality of compressors 2a and 2b merges through the check valves B1 and B2, respectively, and passes through the oil separator 3. After separating the oil when
It enters the indoor heat exchanger 5 via the four-way valve 4. Indoor heat exchanger 5
The refrigerant is radiated and condensed by the air blown into the room,
Heat from the heat is blown into the room to heat the room. The refrigerant that has exited the indoor heat exchanger 5 is decompressed by the indoor decompression device 6 and the outdoor decompression device 8, evaporates in the outdoor heat exchanger 7, and absorbs heat from the engine cooling water in the refrigerant heater 9. ,
After gas-liquid separation by the accumulator 10 through the four-way valve 4, the gas refrigerant is sucked into the plurality of compressors 2a and 2b.

On the other hand, the cooling water of the engine 1
After passing through the thermostat 17, the heat is exchanged with the refrigerant in the refrigerant heater 9, cooled, and returned to the engine 1. When the temperature of the cooling water rises due to an increase in the load of the refrigeration cycle or the like and becomes equal to or higher than the set temperature of the thermostat 17, the thermostat 17 operates to flow the cooling water to the radiator 18 side, and the radiator 18 radiates heat. .

<Defrosting Operation> If the frost sensor 33 detects frost formation on the outdoor heat exchanger 7 during the above-mentioned heating operation, the control circuit 30 energizes the relays R2 and R3, and turns on the relays R4 and R4.
Turn off the power to R5. As a result, the relay contacts r2, r3
Is closed and the relay contacts r4 and r5 are opened. As a result, the first and second solenoid valves 11 and 12 for defrosting are opened, and the indoor fan 1 is opened.
5 operates at the minimum number of revolutions by energization through the resistor R,
The outdoor fan 16 stops. Further, the engine 1 operates at the maximum rotation speed with the throttle (not shown) fully opened.

The flow of the refrigerant during the heating operation will be described.
The high-temperature and high-pressure refrigerant discharged from the one compressor 2a flows from the point A of the branch portion to the first defrost bypass circuit 21 as shown by the dashed arrow, passes through the first defrost electromagnetic valve 11, and is discharged outside the room. Enter the heat exchanger 7. The high-temperature and high-pressure refrigerant dissolves frost formed on the outdoor heat exchanger 7. At this time, the refrigerant condenses. The refrigerant that has exited the outdoor heat exchanger 7 merges with the refrigerant from the second defrost bypass circuit 22 at the point B at the junction, absorbs heat from the engine cooling water in the refrigerant heater 9, and connects with the four-way valve 4. It is sucked into the plurality of compressors 2a and 2b via the accumulator 10.

The high-temperature and high-pressure refrigerant discharged from the other compressor 2b is supplied to the oil separator 3 as shown by a solid line arrow.
, And enters the indoor heat exchanger 5 via the four-way valve 4.
In the indoor heat exchanger 5, the refrigerant is radiated and condensed by the air blown into the room, and heat generated by the radiated heat is blown into the room to heat the room. The refrigerant that has exited the indoor heat exchanger 5 is decompressed by the indoor decompression device 6, flows to the second defrost bypass circuit 22, passes through the second defrost electromagnetic valve 12, and is decompressed by the auxiliary decompression device 13. The refrigerant thus cooled passes through the check valve 14 and merges with the refrigerant from the outdoor heat exchanger 7 at a point B at the junction. Note that the cooling water of the engine 1 circulates in the same manner as in the above-described heating operation.

The control of the defrosting operation by the control circuit 30 will be described with reference to the flowchart of FIG. The frost sensor 33 determines whether or not the outdoor heat exchanger 7 is frosted (step S1). If it is frosted, first,
The second solenoid valves 11 and 12 for defrosting are opened to flow the refrigerant to the first and second bypass circuits 21 and 22 for defrosting, the outdoor fan 16 is stopped, and the indoor fan 15 is operated at the minimum rotation speed. Then, the engine 1 is operated at the maximum rotational speed, and a defrosting operation for simultaneously operating the plurality of compressors 2a and 2b is executed (step S2).

Next, it is determined by the frost sensor 33 whether or not the frost of the outdoor heat exchanger 7 has melted (step S3).
If it is determined that it has not melted, the flow returns to step S2 to continue the defrosting operation, and if it is determined that it has melted, the flow proceeds to step S4 of the normal heating operation. If it is determined in step S1 that no frost has formed, the operation proceeds directly to the heating operation in step S4.

<Cooling operation> When the changeover switch 32 is set to the cooling contact C, the control circuit 30 operates the relay R4,
R5 is energized, and relays R1, R2, R3 are not energized.
As a result, the relay contacts r4 and r5 are closed, and the relay contacts r1, r2 and r3 are opened. As a result, the four-way valve 4 is switched to the cooling side, the first and second solenoid valves 11 and 12 for defrosting are closed, and the indoor fan 15 and the outdoor fan 16 operate at the normal rotation speed.

Explaining the flow of the refrigerant during the cooling operation, the high-temperature and high-pressure refrigerant discharged from the plurality of compressors 2a and 2b pass through the check valves B1 and B2, respectively, and join together. It enters the outdoor heat exchanger 7 via the valve 4 and the refrigerant heater 9. In the outdoor heat exchanger 7, the refrigerant radiates heat to outside air and condenses. The refrigerant that has exited the outdoor heat exchanger 7 is decompressed by the outdoor decompression device 8 and the indoor decompression device 6, absorbs heat from the air blown into the room by the indoor heat exchanger 5, and cools the room. The refrigerant that has absorbed and evaporated in the indoor heat exchanger 5 is vapor-liquid separated by the accumulator 10 through the four-way valve 4, and then the gas refrigerant is sucked into the plurality of compressors 2a and 2b.

On the other hand, the cooling water of the engine 1 returns to the engine 1 through the thermostat 17 and the refrigerant heater 9, but since the heat exchange is not performed in the refrigerant heater 9, the temperature of the cooling water gradually increases, and the temperature of the thermostat 17 is reduced. When the temperature becomes equal to or higher than the set temperature, the thermostat 17 operates and the cooling water flows to the radiator 18, and the radiator 18 radiates heat and returns to the engine 1 in a cycle.

The operations of the four-way valve 4, the first and second defrosting solenoid valves 11, 12, the indoor fan 15, and the outdoor fan 16 in each of the cooling, heating, and defrosting operations described above are summarized in the following table. Like one.

[Table 1]

[Effects of the Embodiment] In the engine-driven heat pump of this embodiment, during the defrosting operation, the high-temperature and high-pressure gas refrigerant discharged from one compressor 2a passes through the first defrost bypass circuit 21. The refrigerant directly flows into the outdoor heat exchanger 7 and melts the frost adhering to the outdoor heat exchanger 7 in a short time, and the high-temperature and high-pressure gas refrigerant discharged from the other compressor 2b is directly cooled by the indoor heat exchanger. 5, the heat is radiated by the indoor heat exchanger 5, so that continuous heating at the time of defrosting is effectively performed. For this reason, the indoor blowing temperature can be maintained high even during defrosting, and the comfort of the indoor user is enhanced.

During the defrosting operation, one of the compressors 2a
, And a heating circuit by the other compressor 2b are separately formed, so that the length of the piping on the indoor heat exchanger 5 side becomes longer or the height difference becomes larger due to the rise of buildings and the like. However, the defrosting operation and the heating operation are simultaneously performed regardless of the magnitude of the pipe resistance on the indoor heat exchanger 5 side. That is, the engine-driven heat pump according to the present embodiment can perform continuous heating defrost, and does not have a problem that the heating effect is weakened by pipe resistance or the like during continuous heating defrost.

[Modification] In the above embodiment, an example was shown in which the first and second defrosting solenoid valves 11 and 12 were closed during the heating operation. 2 The defrosting electromagnetic valve 12 may be opened. Further, the refrigerant heater 9 of the above embodiment uses the engine cooling water as a heat source, but a heat source generated directly or indirectly by driving the engine 1 (for example, a heater that generates heat by power supply of an alternator). Etc.) may be used.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram showing a configuration of an engine-driven heat pump (Example).

FIG. 2 is an electric circuit diagram of an engine drive heat pump (Example).

FIG. 3 is a flowchart illustrating defrosting operation control (embodiment).

FIG. 4 is a refrigerant circuit diagram showing a configuration of an engine-driven heat pump (conventional example).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2a One compressor 2b The other compressor 4 Four-way valve (refrigerant flow direction switching means) 5 Indoor heat exchanger 7 Outdoor heat exchanger 9 Refrigerant heater 11 First defrosting solenoid valve (First on-off valve) 12) Second electromagnetic valve for defrost (second on-off valve) 15 Indoor fan (Blower fan of indoor heat exchanger) 16 Outdoor fan (Blower fan of outdoor heat exchanger) 21 First defrost bypass circuit 22 Second Defrost bypass circuit

Claims (2)

[Claims] An engine-driven heat pump that performs a heating operation and a cooling operation by switching and flowing refrigerant from a plurality of compressors driven by an engine to an indoor heat exchanger side and an outdoor heat exchanger side. A first defrost bypass circuit for flowing the refrigerant discharged from one of the compressors to the upstream side during the heating operation of the outdoor heat exchanger; and opening and closing the first defrost bypass circuit. A first on-off valve, and a second filter that flows the refrigerant discharged from the other one of the plurality of compressors and passed through the indoor heat exchanger to a downstream side during the heating operation of the outdoor heat exchanger. A frost bypass circuit; a second on-off valve for opening and closing the second defrost bypass circuit; and a downstream side provided during a heating operation of the outdoor heat exchanger, the outdoor heat exchanger and the second defrost. Passed through the bypass circuit for And a refrigerant heater for heating, the first during the defrosting operation, engine driven heat pump, characterized in that opening the second on-off valve. 2. The engine-driven heat pump according to claim 1, wherein a blowing fan of said indoor heat exchanger is operated at a low rotation speed during a defrosting operation, and a blowing fan of said outdoor heat exchanger is stopped. An engine-driven heat pump characterized by operating the engine and operating the engine at a high rotational speed.