JP3140215B2 - Cooling / heating mixed engine driven heat pump system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mixed cooling / heating system in which a plurality of indoor units can be operated simultaneously for cooling and the others for heating simultaneously by a heat pump driven by an engine.

[0002]

2. Description of the Related Art A so-called cooling / heating mixed type in which a plurality of indoor units are connected to a single outdoor unit and a part of a plurality of rooms is simultaneously cooled and another is heated by a single system. In a multi-system, the load varies from room to room, and the capacity of the air-cooled heat exchanger of the outdoor unit as a condenser or an evaporator must be adjusted accordingly. This type of system known at present is a system that drives the compressor with an electric motor, responds to this by controlling the rotation speed of the compressor and the fan at a high level, and as a condenser required for cooling. The difference between the maximum capacity of the evaporator required for heating and the maximum capacity of the evaporator required for heating and the appropriate capacity for mixed operation is large. In addition to the above-mentioned control, the air-cooled heat exchanger is divided into three parts with different capacities. Attempts have also been made to change these combinations with solenoid valves to accommodate the required imbalance in cooling / heating capacity.

[0003]

However, in the above-mentioned prior art, the control becomes very complicated and the configuration of the system becomes complicated in order to perform appropriate capacity adjustment.
Furthermore, when the operation is performed with the rotation speed of the fan extremely reduced, there is a problem that the operation is easily affected by the wind and the installation location, and it has been difficult to appropriately cope with a wide range of operation. The present invention has been made in view of such a problem, and has been made to control the cooling / heating capacity in a well-balanced manner by utilizing the cooling water of a driving engine peculiar to an engine-driven heat pump system.

[0004]

According to the present invention, there is provided an engine-driven heat pump system capable of simultaneously operating a part of a plurality of indoor units for cooling and the other for heating simultaneously. By providing an auxiliary heat exchanger that heats the refrigerant by exchanging heat between the refrigerant and the engine cooling water for driving, and using only the auxiliary heat exchanger as the evaporator of the outdoor unit during the operation mainly performed by heating. The operation is performed with the capacity of the evaporator lowered. In order to adjust the capacity of the auxiliary heat exchanger as an evaporator, the refrigerant flow rate of the auxiliary heat exchanger is adjusted, the heat exchange area between the refrigerant and the engine cooling water for driving is adjusted, or the auxiliary heat exchange is performed. Means such as adjusting the flow rate of the driving engine cooling water supplied to the vessel are possible.

[0005]

The auxiliary heat exchanger heats the refrigerant by the cooling water of the driving engine, and acts as an evaporator having a small capacity. The capacity required as an evaporator when operating mainly in heating is equivalent to the difference between the capacity required as an evaporator for an indoor unit being heated and the capacity required as a condenser for an indoor unit being cooled. Therefore, the capacity as an evaporator may be small, and by using an auxiliary heat exchanger, it is possible to easily cope with an operation mainly performed by heating.

[0006]

[Basic Embodiment] Next, the illustrated embodiment will be described. FIG. 1 shows a refrigerant circuit according to a basic embodiment of the present invention. 1 is an indoor unit, 2 is an outdoor unit, and a plurality of indoor units 1, 1... Are connected to one outdoor unit 2 through a high-pressure gas pipe 3, a liquid pipe 4, and a low-pressure gas pipe 5, and one system is provided. Of the system. Indoor unit 1 is heat exchanger 1
a, which includes an electronic expansion valve 1b, and in which the flow of the refrigerant is switched to cooling or heating by the refrigerant branch controller 6. In the figure, three indoor units 1 are shown,
The cooling unit is used for heating, and the other two units are used for heating.

The outdoor unit 2 includes an engine 11 and a compressor 1
2 is a system for driving the air conditioner, 13 is an air-cooled first heat exchanger, 14 is an air-cooled second heat exchanger, 15 is an auxiliary heat exchanger, 16 is an electronic expansion valve, and 17 is an accumulator. ,
18 is a receiver, 19 is an exhaust heat exchanger of the engine 11,
20 is a radiator of the engine 11, 21 is a control unit, 22
Is a cooling water pump. In addition, solenoid valves are inserted at various points in the refrigerant circuit as shown. Auxiliary heat exchanger 1
Reference numeral 5 denotes a sub-evaporator for heating the refrigerant by the cooling water of the engine 11, and as shown in FIG.
a has a double pipe structure in which a coolant pipe 15b penetrates concentrically through the cooling water pipe 15a.
a, and heat exchange is performed with the refrigerant passing through the refrigerant pipe 15b.

The control unit 21 opens and closes each solenoid valve according to the cooling / heating capacity demand obtained from the on / off signals of the indoor units 1, 1... And the temperature of the engine cooling water which is the heat source of the refrigerant. In addition to switching the path of the refrigerant flowing through the auxiliary heat exchanger 14 and the auxiliary heat exchanger 15 to make an optimal combination for controlling the heat exchange capacity, the engine 11, that is, the suction pressure and the discharge pressure of the compressor 12 are set to the optimal operation state. The number of rotations of the compressor 12 is controlled, and the frequency of the fans 13a and 14a of each heat exchanger and the opening of the electronic expansion valve 16 are controlled. The dashed line in FIG. 1 exemplifies a signal line, 25 is a temperature sensor for detecting the temperature of the cooling water of the engine 11, 26 is a temperature sensor for detecting the refrigerant temperature at the outlet of the auxiliary heat exchanger 15, and 27 and 28. Are pressure sensors for detecting the suction pressure and the discharge pressure of the compressor 12, respectively.

Next, the normal heating-main operation state is the A mode, and the cooling / heating capacity demand is unbalanced and the heat exchange capacity of the outdoor unit 2 may be relatively large, or the cooling water temperature is low. A basic control procedure for setting the operation state to the B mode will be described. In FIG. 1, the bold line shows a circuit in which the refrigerant flows, and this figure
4 is not used, and is in the A mode in which the refrigerant flows only in the auxiliary heat exchanger 15. In the B mode, the auxiliary heat exchanger 15 is not used as shown in FIG.

FIG. 4 shows a procedure of an operation mode selection subroutine. First, the operation signal of each indoor unit 1 is input, and the total cooling demand and the total heating demand are compared. If the heating demand is small, the cooling main mode is controlled. On the other hand, when the heating demand is equal to or greater than the cooling demand, the process proceeds to the heating main mode, and when the difference is equal to or less than the reference value C1, the cooling water temperature Tw1 detected by the sensor 25 is equal to or greater than the reference value C2. In some cases, the mode proceeds to the A mode, and otherwise, the mode proceeds to the B mode. In the case of the A mode, first, the flag is checked. If the flag is 0, the mode is not changed. If the flag is 1, the superheat target value in the auxiliary heat exchanger 15 and the initial value of the rotation speed of the compressor 12 in the A mode are set. The flag is set to 0, the solenoid valves are set so that the refrigerant path is in the state shown in FIG. 1, and the flow proceeds to the suction / discharge pressure control routine A of the compressor 12 shown in FIG. Similarly B
In the case of the mode, first, the flag is checked. If the flag is 1, the mode is not changed. If the flag is 0, the initial value of the frequency of the fan 13a and the rotation speed of the compressor 12 in the B mode is set and the flag is set to 1. Each solenoid valve is set such that the refrigerant path is in the state shown in FIG. 3, and the process proceeds to the suction / discharge pressure control routine B of the compressor 12 shown in FIG.

FIG. 5 shows an example of a general control procedure in the routine A.
The suction pressure and the discharge pressure of the compressor 12 detected in steps 7 and 28 are sequentially inputted, and the data is set. Then, by calculating the time series deviation vector and calculating the PID control amount, the control vector corresponding to the number of rotations of the compressor and the degree of superheat of the auxiliary heat exchanger for achieving the control target of the suction pressure and the discharge pressure is read. Calculate the weighting factor,
The PID control amount is multiplied by each weight coefficient to determine the final rotation speed of the compressor 12 and the degree of superheat of the auxiliary heat exchanger. The degree of superheat is detected at the outlet temperature of the auxiliary heat exchanger 15.

FIG. 6 shows an example of a general control procedure in the above-mentioned routine B.
The suction pressure and the discharge pressure of the compressor 12 detected in steps 7 and 28 are sequentially inputted, and the data is set. Then, by calculating the time series deviation vector and calculating the PID control amount, the control vector corresponding to the number of rotations of the compressor and the frequency of the fan for achieving the control target of the suction pressure and the discharge pressure is read, and the weight coefficient is further calculated. And PI
The D control amount is multiplied by each weight coefficient to determine the final rotation speed of the compressor 12 and the frequency of the fan 13a.

[0013]

[0014]

Other Embodiments In order to obtain a predetermined degree of superheat which is targeted in the above-described embodiment, it is necessary to control the amount of superheat of the refrigerant in the auxiliary heat exchanger 15. Hereinafter, embodiments of this control will be described. First, an embodiment corresponding to claim 2 in which the capacity as an evaporator is controlled by adjusting the flow rate of the refrigerant flowing through the auxiliary heat exchanger 15 will be described. When the operation is mainly performed by heating, the liquid-phase refrigerant returns from the liquid pipe 4 to the outdoor unit 2 and passes through the electronic expansion valve 16 to the auxiliary heat exchanger 15.
Therefore, the flow rate is adjusted by controlling the electronic expansion valve 16, and FIG. 7 shows an example thereof. Here, a temperature sensor 31 is provided on the inlet side of the auxiliary heat exchanger 15 to detect the degree of superheat SH (= Tout−Tin) from the inlet temperature Tin and the outlet temperature Tout of the refrigerant, and the control unit 21 controls the electronic expansion valve 16. are doing. The engine cooling water is, for example, about 80 ° C., while the auxiliary heat exchanger 1
Since the temperature of the refrigerant flowing into 5 is about 0 ° C., the degree of superheat can be controlled in this range, and the degree of superheat increases as the flow rate decreases.

Further, since the refrigerant evaporation temperature in the auxiliary heat exchanger 15 has a fixed relationship with the refrigerant inlet temperature Tin, the electronic vaporization temperature is adjusted so that the refrigerant evaporation temperature in the auxiliary heat exchanger 15 becomes a target value depending on the inlet temperature. The refrigerant flow rate may be controlled by the expansion valve 16. Furthermore, a predetermined degree of superheat can be obtained by controlling the suction pressure of the compressor 12 to a predetermined target value, so that the electronic expansion valve 16 is controlled according to the suction pressure detected by the pressure sensor 27. Is also good. By such control, in the embodiment, the superheat amount of the refrigerant can be controlled appropriately and in a wide range, and the fan needs to operate at a very low speed as in the case of the conventional fan frequency control. It does not cause problems such as being sensitive and easily affected by wind.

In order to control the capacity of the auxiliary heat exchanger 15 as an evaporator, the heat exchange area between the refrigerant and the engine cooling water in the auxiliary heat exchanger 15 is adjusted. You can also. FIG. 8 shows an example thereof, wherein (a) shows a case where a plurality of auxiliary heat exchangers 15 are installed in parallel and a bypass line 32 is provided, and these flow paths are appropriately opened and closed by a solenoid valve 33 according to the outlet temperature of the refrigerant. In the configuration (b), a plurality of auxiliary heat exchangers 15 are arranged in series, and a bypass line 32 is provided for each of them, and these flow paths are appropriately opened and closed by a three-way valve 34 according to the outlet temperature of the refrigerant. It was made. Therefore, as the number of auxiliary heat exchangers 15 used increases, the control range becomes wider, and it becomes easier to perform appropriate superheat control. A pressure sensor 3 for detecting the refrigerant pressure at the outlet of the auxiliary heat exchanger as necessary.
5, and the detection result can be used for control. Further, instead of separately providing the plurality of auxiliary heat exchangers 15 as shown in FIG. 8, for example, an integrated structure in which a plurality of refrigerant pipes 15b having different thicknesses are provided in the cooling water pipe 15a may be employed.

Further, the capacity of the auxiliary heat exchanger 15 as an evaporator can be controlled by adjusting the flow rate of the supplied engine cooling water. FIG. 9 shows an example of this, in which a bypass line 37 is provided in the flow path of the cooling water supplied to the auxiliary heat exchanger 15 and the pressure sensor 27 is provided.
The bypass line 37 is opened and closed by the solenoid valve 38 in accordance with the suction pressure detected in step (1), and the cooling water flow rate is controlled so that the refrigerant evaporation temperature in the auxiliary heat exchanger 15 becomes the target value.
The cooling water flow rate can be adjusted by, for example, changing the rotation speed of the cooling water pump 22 by frequency control or the like.

[0018]

As is apparent from the above description, the present invention provides an auxiliary heat exchanger for exchanging heat between a refrigerant and driving engine cooling water in a mixed cooling / heating engine driving heat pump system. In addition, when the operation is mainly performed by heating, only the auxiliary heat exchanger is used as a device corresponding to the evaporator of the outdoor unit, so that the operation is performed with the capacity of the evaporator reduced.
Therefore, the refrigerant can be heated by utilizing the cooling water of the driving engine specific to the engine-driven heat pump system during the heating-main operation in which the capacity as the evaporator may be small. It is possible to perform stable and wide-ranging control without being affected by the wind or the installation location, and it is possible to make use of the cooling water of the driving engine to compensate for the lack of the heating capacity.

[Brief description of the drawings]

FIG. 1 is a refrigerant circuit diagram of a basic embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an auxiliary heat exchanger of the embodiment.

FIG. 3 is a diagram showing a main part of the refrigerant circuit of the embodiment.

FIG. 4 is a flowchart showing a control procedure of the embodiment.

FIG. 5 is a flowchart showing a control procedure.

FIG. 6 is a flowchart showing a control procedure.

FIG. 7 is a schematic diagram showing a configuration of another embodiment.

FIG. 8 is a schematic diagram showing a configuration of another embodiment.

FIG. 9 is a schematic diagram showing a configuration of still another embodiment.

Continuation of front page (72) Inventor Tomoki Hayashi 1-32 Chaya-cho, Kita-ku, Osaka-shi Yanmar Diesel Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) F25B 27/02 F25B 29/00 361 F24F 5/00

Claims (4)

(57) [Claims] An engine-driven heat pump system capable of simultaneously operating a part of a plurality of indoor units for cooling and another for heating, wherein heat is exchanged between a refrigerant and engine cooling water for driving. Providing an auxiliary heat exchanger that heats the refrigerant, and using only the auxiliary heat exchanger as the evaporator of the outdoor unit during operation mainly for heating, to reduce the capacity of the evaporator and to operate. A mixed cooling / heating type engine driven heat pump system characterized by the following features. 2. The cooling / heating mixed engine driven heat pump system according to claim 1, wherein the capacity as an evaporator is controlled by adjusting the flow rate of the refrigerant in the auxiliary heat exchanger. 3. The cooling / heating mixture according to claim 1, wherein the capacity as an evaporator is controlled by adjusting a heat exchange area between the refrigerant and the driving engine cooling water in the auxiliary heat exchanger. Type engine driven heat pump system. 4. A mixed cooling / heating engine driven heat pump according to claim 1, wherein the capacity as an evaporator is controlled by adjusting the flow rate of the driving engine cooling water supplied to the auxiliary heat exchanger. system.