JP5069952B2 - AIR CONDITIONER AND CONTROL METHOD FOR AIR CONDITIONER - Google Patents

Description

  The present invention relates to an air conditioner, and more particularly, to an air conditioner that performs an air conditioning operation by driving a compressor by an engine, and a control method for the air conditioner.

Conventionally, a gas heat pump type air conditioner is known in which a compressor is driven by an engine using natural gas or the like as a fuel to perform air conditioning operations such as cooling operation and heating operation. Among this type of gas heat pump type air conditioner, there is one in which an engine is detachably connected to a compressor via a clutch (see, for example, Patent Document 1).
JP 2001-263765 A

By the way, when the engine is stopped along with the operation stop of the conventional air conditioner, the engine is stopped by stopping the fuel supply to the engine while the engine is connected to the compressor via the clutch. It was.
However, when the engine is stopped by the above method in a state where a load is applied to the compressor, the engine may suddenly stop together with the compressor due to the load of the compressor, generating a loud sound or vibration.

  This invention is made | formed in view of the situation mentioned above, and suppresses the sound and vibration at the time of stopping a compressor and an engine in the air conditioning apparatus which drives a compressor with an engine and performs an air-conditioning driving | operation.

In order to solve the above problems, an air conditioner of the present invention includes a clutch that connects a compressor driven by an engine to the engine so as to be able to contact and separate, a fuel cutoff valve that shuts off a fuel supply to the engine, When the compressor is driven by the engine and a signal instructing to stop the compressor and the engine is input, the clutch is driven to disconnect the compressor from the engine, and the engine rotation Multiplying the number by the first coefficient, multiplying the refrigerant suction pressure by the second coefficient, and subtracting the value obtained by the multiplication from a certain constant, respectively, so that the engine blow-off can be avoided. The valve operation timing is calculated. When the operation timing is positive, the operation timing is calculated. When the operation timing is negative, the operation timing is calculated. As the operation timing a preset value as the shortest time, and a control unit for interrupting the fuel supply to the engine by operating the fuel shut-off valve, wherein the control unit instructs the stop of the compressor The engine load when a signal to be input is input, and the compressor and the engine are separated by the clutch according to the detected load, and then the fuel supply to the engine is performed by the fuel cutoff valve. It is characterized by changing the time until blocking .
According to this configuration, when a signal instructing to stop the compressor is input, the compressor is disconnected from the engine, and then the fuel supply to the engine is cut off. The engine stops in the released state. For this reason, the engine is shut off naturally without being affected by the load of the compressor, and the compressor is quickly stopped by the load for compressing the refrigerant.
Thereby, since the engine is not suddenly stopped together with the compressor as in the conventional case, it is possible to suppress sound and vibration when the engine is stopped. By preventing the engine from suddenly stopping, it is possible to improve the life and reliability of the refrigerant piping and the engine accessory parts, and the number of parts can be reduced by eliminating the need for vibration countermeasure parts.

In addition, by changing the time from when the compressor is disconnected from the engine until the fuel supply to the engine is cut off, depending on the engine load when a signal to stop the compressor is input, The time during which the engine operates after the load from the compressor is eliminated can be adjusted according to the engine load.
In the above air conditioner, when the compressor and the engine are disconnected by the clutch in a state where a large load is applied to the compressor, the engine is suddenly released from the large load. When the fuel is continuously supplied after the load is released, the rotational speed rapidly increases as the load is suddenly reduced, and so-called blow-up occurs. If the engine speed rises excessively due to blowing up, there are concerns about the impact on engine durability and the generation of noise. According to the above configuration, by changing the time from release of the load by the clutch to fuel cutoff according to the engine load, for example, when the engine load is high, the time to fuel cutoff is shortened. Can be avoided. As a result, it is possible to avoid a sudden change in the rotational speed when the engine is stopped, to ensure the durability and reliability of each part including the engine, and to prevent the generation of excessive noise.

The said structure WHEREIN: The said control part is good also as a structure which detects the load of the said engine based on the rotation speed of the said engine when the signal which instruct | indicates the stop of the said compressor is input.
In the above configuration, the air conditioner includes a pressure sensor that detects a pressure on the suction side of the compressor, and the control unit detects a load of the engine based on a detection value of the pressure sensor. It is good also as a structure.

According to another aspect of the present invention, there is provided an air conditioner including: a clutch that connects a compressor driven by an engine to the engine so as to be able to contact and separate; and a fuel cutoff valve that shuts off a fuel supply to the engine. When the compressor is driven by the engine and a signal instructing to stop the compressor and the engine is input, the clutch is driven to disconnect the compressor from the engine. The fuel capable of avoiding engine blow-up by multiplying the number of revolutions by a first coefficient, multiplying the refrigerant suction pressure by a second coefficient, and subtracting values obtained by the multiplication from certain constants, respectively. The operation timing of the shut-off valve is calculated. When the operation timing is positive, the operation timing is calculated. When the operation timing is negative, the operation timing is calculated. A preset value as the shortest time as the operation timing, said fuel cutoff valve is operated to cut off the fuel supply to the engine, load of the engine when the signal for instructing the stop of the compressor is input In accordance with the detected load, the time from when the compressor and the engine are separated by the clutch until the fuel supply to the engine is shut off by the fuel shut-off valve is changed. Provided is a method for controlling an air conditioner.
According to this method, when a signal instructing to stop the compressor is input, the compressor is disconnected from the engine, and then the fuel supply to the engine is cut off. The engine is stopped in the released state, the engine is cut off naturally without being affected by the load of the compressor, and the compressor is quickly stopped by the load for compressing the refrigerant. Therefore, since the engine is not suddenly stopped together with the compressor, the noise and vibration when the engine is stopped can be suppressed, and the life and reliability of the refrigerant piping and the engine accessory parts can be improved. By eliminating the need for parts, the number of parts can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the sound and vibration at the time of stopping a compressor and an engine can be suppressed in the air conditioning apparatus which drives a compressor with an engine and performs an air-conditioning driving | operation.

Embodiments of the present invention will be described below with reference to the drawings.
In FIG. 1, schematic structure of the air conditioning apparatus 1 which concerns on this Embodiment is shown. An air conditioner 1 shown in FIG. 1 is a gas heat pump type air conditioner in which compressors 31a and 31b are driven by an engine 40 using fuel gas as fuel, and includes a plurality of indoor units 2 and a single outdoor unit. 3.
The indoor unit 2 includes an indoor heat exchanger 22 and a blower 23 that blows air to the indoor heat exchanger 22, and cools and heats the conditioned room.

The outdoor unit 3 includes compressors 31a and 31b, an electromagnetic four-way valve 32, a plate heat exchanger 34, an outdoor heat exchanger 36, a blower 37 that blows air to the outdoor heat exchanger 36, and the like. . The two compressors 31a and 31b included in the outdoor unit 3 are connected to the engine 40 through electromagnetic clutches 38a and 38b, respectively, so as to be able to contact and separate.
The compressor 31a and the compressor 31b are preferably compressors having different capacities. In this case, since the compressors 31a and 31b having different capacities can be independently connected to the engine 40 by the clutches 38a and 38b, a compressor having an appropriate processing capacity can be selected and operated according to the air conditioning load. The COP (Coefficient of Performance) of the air conditioner 1 can be improved.

  The indoor heat exchanger 22, the compressors 31a and 31b, the four-way valve 32, the plate heat exchanger 34, the outdoor heat exchanger 36 and the like constitute a refrigerant circuit of the air conditioner 1, and the indoor unit 2 and the outdoor unit 3 are The refrigerant pipe 70 is connected.

  The outdoor unit 3 includes an engine 40 that drives the compressors 31a and 31b, an exhaust gas heat exchanger 51 that exchanges heat between the cooling water of the engine 40 and the exhaust gas, in addition to the components constituting the refrigerant circuit described above. , A thermostat 52, an electric three-way valve 53, an electric cooling water pump 54, and the like, which constitute a cooling water circuit. An exhaust pipe 51a is connected to the exhaust gas heat exchanger 51 via a drain filter (not shown), and a cooling water tank (not shown) is connected to the cooling water pump 54 via a pipe (not shown). Has been.

  The outdoor unit 3 includes a central control device 60 that drives and controls the four-way valve 32, the three-way valve 53, the blower 37, and the like via control lines (not shown). The central control device 60 includes a CPU (not shown), an input / output interface, a ROM, a RAM, a timer counter, and the like, as well as operation and stop of the engine 40, the engine 40 and the compressor 31a by the clutches 38a and 38b, The engine control part 60a which controls the connection state etc. with 31b is provided.

The input / output interface of the central controller 60 is provided in a cooling water pipe 82 between the engine 40 and the thermostat 52, and is attached to a water temperature sensor 61 that detects the temperature of the cooling water of the engine 40 and the outdoor heat exchanger 36. The heat exchange temperature sensor 62 for detecting the surface temperature of the radiation fins (not shown) of the outdoor heat exchanger 36, the outdoor air temperature sensor 63 attached to the outer wall surface of the outdoor unit 3, and the engine rotation for detecting the rotational speed of the engine 40 A number sensor 44 and a pressure sensor 76 for detecting the pressure on the suction side of the compressors 31a and 31b are connected.
The central control device 60 is connected to a control unit (not shown) on the indoor unit 2 side, and sends / receives signals to / from the control unit to set the air conditioning set by the control unit or the like. The four-way valve 32, the three-way valve 53, and the like are switched so as to operate, and each part of the air conditioner 1 is controlled so that the temperature in each room becomes the air conditioning set temperature.

  When the central controller 60 determines that the compressor 31 needs to be driven, such as when the room temperature does not reach the air conditioning set temperature, a thermo-on signal, that is, a compressor operation start signal is sent to the engine control unit 60a. Input from the control device 60. Here, the central control device 60 selects one or both of the compressors 31a and 31b in order to obtain an appropriate processing capacity according to the air conditioning load, and sends a control signal instructing to drive the selected compressor. To the engine controller 60a. The engine control unit 60a transmits an engine 40 control signal according to the input control signal, drives the starter STR, and starts the engine 40. Further, the engine control unit 60a supplies a control signal and a drive current to a clutch connected to the compressor selected by the central controller 60 among the clutches 38a and 38b, and drives the clutch to switch on the electromagnet. The power of the engine 40 is transmitted to the compressor selected from among the compressors 31a and 31b.

  When the central controller 60 determines that the drive of the compressor 31 needs to be stopped, for example, the room temperature exceeds the air conditioning set temperature, a thermo-off signal, that is, a compressor stop instruction signal is sent to the engine controller 60a. Entered. When the compressor stop instruction signal is input from the central controller 60, the engine control unit 60a stops the compressor that is being driven, so that the drive current to the clutch in the connected state of the clutches 38a and 38b is reduced. Stop the supply and disconnect the clutch. As a result, the compressors 31a and 31b are stopped while the engine 40 continues to operate. Note that the engine control unit 60a drives the clutches 38a and 38b, so that, for example, only one of the compressors can be stopped while both the compressors 31a and 31b are in operation.

  In addition, when stopping the air conditioning operation, a compressor stop instruction signal is input from the central controller 60 to the engine controller 60a. Here, the compressor stop instruction signal output by the central controller 60 is a signal instructing to stop all of the operating compressor and the engine 40. When this compressor stop instruction signal is input, the engine control unit 60a executes a process of stopping the engine 40 together with the compressors 31a and 31b during operation. This process will be described later.

  In the air conditioner 1 configured as described above, when the heating operation is started, the refrigerant that flows from the refrigerant pipe 70 to the outdoor unit 3 side flows into the outdoor heat exchanger 36 through the expansion valve 35 of the outdoor unit 3. Then, it evaporates in the outdoor heat exchanger 36 and flows into the plate heat exchanger 34 via the refrigerant pipe 71, the four-way valve 32, and the refrigerant pipe 72, and is heated by the cooling water to be sucked into the compressors 31a and 31b. Reach side conduit. The plate heat exchanger 34 is a double-pipe heat exchanger in which cooling water passes around the refrigerant pipe, and the outdoor heat exchanger 36 is connected to the refrigerant pipe and the cooling water pipe via plate fins. It becomes the composition. The high-temperature refrigerant discharged from the compressors 31 a and 31 b flows into the indoor heat exchanger 22 on the indoor unit 2 side via the refrigerant pipe 74, the four-way valve 32, and the refrigerant pipe 70 and is blown by the blower 23. After heat exchange is performed on the room air, the room air is heated, and then flows again from the refrigerant pipe 70 to the outdoor unit 3 side.

  On the other hand, in the air conditioner 1, when the cooling operation is started, the refrigerant discharged from the compressors 31a and 31b flows from the refrigerant pipe 74 through the four-way valve 32 into the refrigerant pipe 71 and enters the outdoor heat exchanger 36. It flows in and is condensed. The condensed liquid refrigerant flows through the refrigerant pipe 70, passes through the expansion valve 21, and flows into the indoor heat exchanger 22 on the indoor unit 2 side. The refrigerant expanded by the expansion valve 21 evaporates in the indoor heat exchanger 22, performs heat exchange on the indoor air blown by the blower 23, cools it, and then returns from the refrigerant pipe 70 to the outdoor unit 3 side again. Inflow. The refrigerant that has flowed into the outdoor unit 3 reaches the suction-side pipelines of the compressors 31a and 31b via the four-way valve 32, the refrigerant pipe 72, and the refrigerant pipe 73.

In addition, the refrigerant flowing through the refrigerant circuit exchanges heat with the cooling water of the engine 40 during the heating operation. That is, the cooling water discharged from the cooling water pump 54 flows into the exhaust gas heat exchanger 51 via the cooling water pipe 81 and is heat exchanged with the exhaust gas of the engine 40, and then the cooling water path of the engine 40. Flow into. Cooling water that has become high temperature by cooling the engine 40 passes through the outdoor heat exchanger 36 via the cooling water pipe 82, the thermostat 52, and the cooling water pipe 83, and then the cooling water pipe 84, the three-way valve 53, the cooling It passes through the water pipe 85 and flows into the plate heat exchanger 34. In the plate heat exchanger 34, heat is exchanged between the cooling water and the refrigerant, and the refrigerant is heated by the heat of the cooling water. Thereafter, the cooling water is recirculated to the cooling water pump 54 via the cooling water pipe 86 and the cooling water pipe 87.
When the temperature of the cooling water is low, such as immediately after the engine 40 is started, the cooling water is sent to the bypass pipe 88 by the thermostat 52 and circulated through the bypass pipe 88 until the temperature rises to an appropriate temperature.

Next, a schematic configuration around the engine 40 will be described with reference to FIG.
As described above, the engine 40 is detachably connected to the compressors 31a and 31b by the electromagnetic clutches 38a and 38b, respectively, and the power of the engine 40 is transmitted to the compressors 31a and 31b. The compressors 31a and 31b driven by the engine 40 compress the refrigerant, and various air conditioning operations such as the heating operation and the cooling operation described above are performed.
A pulley 41 is attached to the output shaft 40a of the engine 40, and a belt 42 is stretched between the pulley 41 and the pulleys 43a and 43b. The pulleys 43a and 43b are connected to the input shafts 310a and 310b of the compressors 31a and 31b via the clutches 38a and 38b, respectively. It is transmitted to the shafts 310a and 310b.

  The engine 40 is a gas engine operated using gas as fuel. The high-pressure fuel gas supplied from the gas line passes through the fuel cutoff valve 95 and is supplied to the zero governor (pressure governor) 96. The high-pressure gas is adjusted to atmospheric pressure by the zero governor 96 and supplied to the fuel adjustment valve 93. The fuel adjustment valve 93 is a valve that adjusts the amount of fuel supplied to the engine 40 under the control of the engine control unit 60a. The fuel gas adjusted by the fuel adjustment valve 93 is mixed with the air taken from the outside via the air cleaner 97 and supplied to the throttle adjustment valve 94. The throttle adjustment valve 94 controls the amount of air-fuel mixture (fuel / air mixture) fed into the engine 40 in accordance with the required rotational speed and required load of the engine 40. The air-fuel mixture that has passed through the throttle adjustment valve 94 is supplied to the engine 40 via the fuel supply pipe 91. The fuel shut-off valve 95 is a valve that is arranged in two and operates two valves simultaneously. As will be described later, when a control signal instructing fuel shut-off is input from the engine control unit 60a, the fuel shut-off valve 95 Shut off the fuel.

In the air conditioner 1, when the engine 40 is stopped, the engine control unit 60a drives the clutches 38a and 39b and the fuel cutoff valve 95 in response to a compressor stop instruction signal from the central control device 60. . Here, when both the clutches 38a and 38b are disconnected and disconnected at the timing of stopping the engine 40, the engine control unit 60a transmits a control signal to the fuel cutoff valve 95, and the fuel is cut off. The fuel supply is shut off by the shut-off valve 95.
Further, when any one or more of the clutches 38a and 38b are connected at the timing when the engine 40 is to be stopped, the engine control unit 60a drives and disconnects the clutches 38a and 38b. A control signal is transmitted to the cutoff valve 95 and the fuel supply is shut off by the fuel cutoff valve 95.

Conventionally, the engine 40 has been stopped by shutting off the fuel supply in a state where loads by the compressors 31a and 31b are connected. In this state, the engine 40 is stopped together with the compressors 31a and 31b by the loads of the compressors 31a and 31b. As a result, the engine 40 was suddenly stopped, and sound and vibration were generated along with the sudden stop.
However, as in the present embodiment, when the engine 40 is stopped, the clutches 38a and 38b are driven to disconnect the compressors 31a and 31b from the engine 40, and then the fuel shut-off valve 95 is operated to supply fuel to the engine 40. If the supply is cut off, both the engine 40 and the compressors 31a and 31b naturally stop when the engine 40 is stopped, so that the sudden stop does not occur and the sound and vibration can be greatly suppressed. Further, in the air conditioner 1 according to the present embodiment, the time from when the clutch 38a, 38b is disconnected by the engine control unit 60a until the fuel supply is shut off by the fuel cutoff valve 95 varies according to the load of the engine 40. It is also possible to make it. Here, the load of the engine 40 is detected by the engine speed sensor 44 and the pressure sensor 76 on the suction side of the compressor.

Hereinafter, the processing when the engine is stopped will be described in detail.
FIG. 3 is a flowchart showing processing when the engine is stopped.
First, the engine control unit 60a waits until a stop instruction signal (thermo-off signal) is input to the compressors 31a and 31b (step S1: No). When the stop instruction signal is input (step S1: Yes), the engine control unit 60a checks whether either one or both of the clutches 38a and 38b are connected (step S2).
Here, when either or both of the clutches 38a and 38b are connected (step S2: Yes), the engine control unit 60a refers to the detection values of the engine speed sensor 44 and the pressure sensor 76 (step S3). ).

Then, the engine control unit 60a obtains a value corresponding to the load of the engine 40 based on the detection value referenced in step S3, and obtains the operation timing A of the fuel cutoff valve 95 based on the value (step S4). This operation timing A is the time from when the clutches 38a and 38b are disconnected until the fuel is shut off by the fuel shut-off valve 95. The engine control unit 60a calculates the operation timing A by a predetermined arithmetic expression, for example, as shown in the following expression (1).
A = 2− (engine speed) × 0.0005− (refrigerant suction pressure) × 0.4 (1)
Here, the unit of the operation timing A is second, the unit of the engine speed is the number of revolutions per minute (rpm), and the unit of the refrigerant suction pressure is MPa. The above equation (1) is appropriately changed according to the type and characteristics of the refrigerant and the engine.
In addition, when the value of the operation timing A calculated by the above equation (1) becomes a negative value, the engine control unit 60a does not use the value calculated by the above equation (1) and the shortest of the operation timing A. The operation timing A is a value set in advance as time.

Thereafter, the engine control unit 60a disconnects the clutches 38a and 38b (step S5), and starts counting the timer simultaneously with the release of the clutches 38a and 38b (step S6).
The engine control unit 60a determines whether or not the count value B of the timer has increased to the value of the operation timing A of the fuel cutoff valve 95 calculated in step S4 (step S7), and the count value B is determined to be the fuel cutoff valve 95. Is reached (step S7: Yes), the fuel cutoff valve 95 is operated to cut off the fuel supply to the engine 40 (step S8). As a result, the engine 40 is stopped.

When the count value B of the timer is smaller than the value of the operation timing A of the fuel cutoff valve 95 (step S7: No), the engine control unit 60a increases the count value B to the value of the operation timing A of the fuel cutoff valve 95. Wait until
On the other hand, when both the clutches 38a and 38b are not connected in step S2 and the engine is operating (step S2: No), the engine control unit 60a operates the fuel cutoff valve 95 to connect to the engine 40. The fuel supply is shut off (step S8), and the engine 40 is stopped.

  As described above, according to the embodiment to which the present invention is applied, the engine control unit 60a of the air conditioner is configured so that when the signal instructing the stop of the compressors 31a and 31b is input, the compressor 31a, 31b is disconnected from the engine 40 by the clutches 38a and 38b, and then the connection between the engine 40 and the compressors 31a and 31b is released in order to control the fuel cutoff valve 95 to shut off the fuel supply to the engine 40. Since the engine 40 is stopped in the state, the sound and vibration when the engine is stopped can be suppressed.

  Further, the engine control unit 60a detects the load of the engine 40 when a signal instructing the stop of the compressors 31a and 31b is input, and the compressors 31a and 31b and the engine 40 are connected according to the detected load. Since the operation timing A, which is the time until the fuel supply to the engine 40 is shut off by the fuel shut-off valve 95, is changed after the disconnection, the time that the engine 40 continues to operate after the load is lost is set as the load of the engine 40. Since it can be adjusted accordingly, engine blow-up can be avoided.

Further, the engine control unit 60a can detect the load of the engine 40 based on the number of revolutions of the engine 40 when a signal instructing to stop the compressors 31a and 31b is input, and the compressors 31a and 31b. The load of the engine 40 may be detected based on the detection value of the pressure sensor 76 when a signal instructing the stop of the compressors 31a and 31b is input using the pressure sensor 76 that detects the pressure on the suction side of the compressor. it can.
Furthermore, the engine control unit 60a can detect the load of the engine 40 using both the rotational speed of the engine 40 and the detected values of the pressure sensor 76.

In the above-described embodiment, the time from when the clutches 38a and 38b are driven to disconnect the compressors 31a and 31b from the engine 40 until the fuel supply is shut off by the fuel cutoff valve 95 is defined as the load of the engine 40. It was changed accordingly. According to this control, the operation of the clutches 38a and 38b and the stop of the engine 40 are ensured in order by providing a time margin between the operation timing of the clutches 38a and 38b and the stop timing of the engine 40. Can be executed. Therefore, even if the precision of the clutches 38a and 38b and the fuel cutoff valve 95 is low, the operation can be surely performed, and there is an advantage that each device can be surely protected. Further, if the value of the operation timing A is not extremely large, the increase in fuel consumption due to the delay of the stop timing of the engine 40 is slight.
However, the present invention is not limited to this. For example, in order to perform simpler control, the engine 49 is stopped after a predetermined time has elapsed after the clutches 38a and 38b are disconnected. You may let them. Hereinafter, this case will be described.

  FIG. 4 is a flowchart showing another example of processing when the engine is stopped in the embodiment to which the present invention is applied. In the process shown in FIG. 4, the engine control unit 60a disconnects the compressors 31a and 31b and the engine 40 by the clutches 38a and 38b, and then the fuel cutoff valve 95 within a predetermined time determined in advance through experiments or the like. The fuel supply to the engine 40 is shut off.

In the process shown in FIG. 4, the engine control unit 60a waits until a stop instruction signal (thermo-off signal) is input to the compressors 31a and 31b (step S11: No). When the stop instruction signal is input (step S11: Yes), the engine control unit 60a checks whether either one or both of the clutches 38a and 38b are connected (step S12).
Here, when either one or both of the clutches 38a and 38b are connected (step S12: Yes), the engine control unit 60a disconnects the clutches 38a and 38b (step S13), and releases the clutches 38a and 38b. At the same time, the timer starts counting (step S14).

Then, the engine control unit 60a determines whether or not the count value B of the timer has increased to a preset value of the operation timing A of the fuel cutoff valve 95 (step S15).
Here, when the count value B reaches the value of the operation timing A (step S15: Yes), the engine control unit 60a operates the fuel cutoff valve 95 to shut off the fuel supply to the engine 40 (step S16).
When the count value B is smaller than the value of the operation timing A (step S15: No), the engine control unit 60a waits until the count value B reaches the value of the operation timing A of the fuel cutoff valve 95.
If both the clutches 38a and 38b are not connected in step S12 and the engine is in operation (step S12: No), the engine control unit 60a operates the fuel cutoff valve 95 to supply fuel to the engine 40. Supply is interrupted (step S16), and the engine 40 is stopped.

According to the process shown in FIG. 4, the time from when the clutches 38a and 38b are driven and the compressors 31a and 31b are disconnected from the engine 40 to when the fuel supply is cut off is set as a fixed time in advance. Thus, it is not necessary for the engine control unit 60a to perform arithmetic processing, load detection, or the like when the engine 40 is stopped. For this reason, there is an advantage that the engine can be stopped quickly and there is no need to provide a processing unit for detecting the load, etc., and the engine 40 and the compressors 31a and 31b have a simplified operation and configuration. The sound and vibration when stopping can be suppressed.
The value of the operation timing A in this case is a short time (small value) so as to prevent blow-up when the loads on the compressors 31a and 31b are high, but the clutches 38a and 38b and the fuel shut-off valve 95 are highly accurate. As long as the operation can be performed reliably, it is possible to achieve a practically sufficient working effect.

In addition, the said embodiment is one aspect to which this invention is applied, and of course, this invention is not limited to the said embodiment. For example, in the above-described embodiment, the air conditioner 1 including a plurality of indoor units 2 has been described as an example. However, the number of indoor units 2 is not particularly limited, and one outdoor unit 3 is included. On the other hand, one indoor unit 2 may be connected. Further, for example, in the above-described embodiment, the fuel cutoff valve 95 that shuts off the fuel supply to the engine 40 is provided, and the fuel cutoff valve 95 is operated to stop the engine 40. For example, the fuel adjustment valve 93 that adjusts the fuel supplied to the engine 40 may be configured to shut off the fuel. Moreover, in the said embodiment, although it was set as the structure provided with the cooling water circuit containing the plate heat exchanger 34 etc. which heat-exchange the cooling water and refrigerant | coolant of the engine 40, the structure which concerns on each part of this cooling water circuit is arbitrary. is there.
Furthermore, although the engine control unit 60a has been described as a configuration that realizes the timer function in the above-described embodiment, for example, another microcomputer may function as a timer. The engine 40 may use a gas such as natural gas as fuel. It is not limited to the engine to be used, and it may be operable with gasoline, light oil, or heavy oil as fuel, and it is needless to say that other detailed configurations can be arbitrarily changed.

It is a figure which shows the refrigerant circuit and cooling water circuit which show an example of the air conditioning apparatus which concerns on embodiment to which this invention is applied. It is a figure which shows the structure around the engine with which the air conditioning apparatus which concerns on embodiment is provided. It is a flowchart which shows the process at the time of the engine stop which concerns on embodiment. It is a flowchart which shows the process at the time of the engine stop as another example of embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Indoor unit 3 Outdoor unit 22 Indoor heat exchanger 31a, 31b Compressor 32 Four-way valve 34 Plate heat exchanger 36 Outdoor heat exchanger 38a, 38b Clutch 40 Engine 40a Output shaft 44 Engine speed sensor 51 Exhaust gas Heat exchanger 60 Central controller 60a Engine controller 76 Pressure sensor 91 Fuel supply pipe 93 Fuel adjustment valve 95 Fuel shut-off valve

Claims (4)

A clutch for connecting a compressor driven by the engine to the engine in a detachable manner;
A fuel cutoff valve for shutting off fuel supply to the engine;
When the compressor is driven by the engine and a signal instructing to stop the compressor and the engine is input, the clutch is driven to disconnect the compressor from the engine, and the engine rotation Multiplying the number by the first coefficient, multiplying the refrigerant suction pressure by the second coefficient, and subtracting the value obtained by the multiplication from a certain constant, respectively, so that the engine blow-off can be avoided. When the operation timing is positive, the operation timing is positive, and when the operation timing is negative, when the operation timing is negative, the value set in advance as the shortest time of the operation timing is used as the operation timing. A controller that operates to shut off the fuel supply to the engine ,
The control unit detects a load of the engine when a signal instructing to stop the compressor is input, and after separating the compressor and the engine by the clutch according to the detected load, An air conditioner that changes a time until the fuel supply to the engine is shut off by the fuel shut-off valve . The air conditioner according to claim 1 , wherein
The control unit detects a load of the engine based on a rotational speed of the engine when a signal instructing to stop the compressor is input;
An air conditioner characterized by. The air conditioner according to claim 1 or 2 ,
A pressure sensor for detecting the pressure on the suction side of the compressor;
The controller detects a load of the engine based on a detection value of the pressure sensor;
An air conditioner characterized by. Controlling an air conditioner comprising: a clutch that connects a compressor driven by the engine to the engine so as to be able to contact and separate; and a fuel cutoff valve that shuts off fuel supply to the engine;
When the compressor is driven by the engine and a signal instructing to stop the compressor and the engine is input, the clutch is driven to disconnect the compressor from the engine, and the engine rotation Multiplying the number by the first coefficient, multiplying the refrigerant suction pressure by the second coefficient, and subtracting the value obtained by the multiplication from a certain constant, respectively, so that the engine blow-off can be avoided. When the operation timing is positive, the operation timing is positive, and when the operation timing is negative, when the operation timing is negative, the value set in advance as the shortest time of the operation timing is used as the operation timing. wherein d when it is operated to cut off the fuel supply to the engine, a signal for instructing stop of the compressor is input Detecting a load of the gin in response to the detected load and disconnect said said compressor engine by the clutch, by the fuel shut-off valve Ru changing the time to be cut off the fuel supply to the engine thing,
A control method for an air conditioner.

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