JPH08247565A - Heat pump multi system - Google Patents

Abstract

(57) [Summary] [Object] To provide a heat pump multi-system capable of preventing an increase in noise on the user side during a stop during heating operation, even if control is performed to obtain an appropriate refrigerant flow rate. [Configuration] When configured as an air conditioner, a control unit 22 that changes the opening of the stop room electric expansion valve EV _{y at} a minute opening in proportion to the change of the opening of the driving room electric expansion valve EV _x during heating operation. To provide. The control means 22 controls the indoor heat exchanger 8 while the opening of the stopped room electric expansion valve EV _y is stopped.
The limit opening degree Q _x that can prevent the liquid pool at is changed as the lower limit. An opening degree command output unit 23 that outputs an opening degree command signal to each of the electric expansion valves EV _{1 to} EV ₃ is provided, and the limit opening degree Q _x takes into consideration the error existing in each of the electric expansion valves EV _{1 to} EV _3. , opening command signal _{P x} which can ensure a critical angle _{Q x}
Set as.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pump multi-system in which a plurality of heat exchangers on the heat source side can be connected to a heat exchanger on the heat source side.

[0002]

2. Description of the Related Art Generally, in a heat pump multi-system in which a plurality of heat exchangers on the use side can be connected to a heat exchanger on the heat source side, liquid pipes and gas pipes connected to the heat exchanger on the heat source side are generally used. , A plurality of liquid branch pipes and gas branch pipes corresponding to the number of connectable heat exchangers on the use side are connected, and solenoid valves are provided on each of these branch pipes. Was opening and closing. However, because the solenoid valve has a structure that switches between fully open and fully closed, the utilization side heat exchanger has a cooling expansion mechanism and a check valve that bypasses this expansion mechanism, and a heat source side heat exchanger side. It was necessary to provide an expansion mechanism for heating and a check valve that bypasses this expansion mechanism. Further, in the heat exchanger on the use side, which is stopped during the heating operation, there is a risk that refrigerant will leak from the solenoid valve provided on the gas branch pipe and accumulate, so it is necessary to provide a bypass circuit to remove this refrigerant to the low pressure side. However, there is a problem that the refrigerant circuit becomes complicated, which is one of the causes of increasing the cost.

As a solution to this problem, there is a heat pump multi-system described in Japanese Patent Publication No. 3-20666. FIG. 1 is a diagram showing a refrigerant circulation system in an embodiment in which the present invention is configured as an air conditioner. The above conventional example configured as an air conditioner will be described with reference to this figure. As shown in the figure, the air conditioner includes a compressor 1, a four-way switching valve 2, an outdoor heat exchanger 3 functioning as a heat source side heat exchanger, a liquid pipe 4, and a plurality of liquids branched from the liquid pipe 4. One outdoor unit A provided with a branch pipe 5, a gas pipe 6, and a plurality of gas branch pipes 7 branched from the gas pipe 6, and an indoor heat exchanger 8 functioning as a use side heat exchanger.
An indoor fan 9 and a plurality of indoor units B connected in parallel between the liquid branch pipe 5 and the gas branch pipe 7 via a plurality of connecting pipes C. And the heating operation in which the refrigerant is circulated from the indoor heat exchanger 8 to the outdoor heat exchanger 3 by switching the four-way switching valve 2 to which the discharge pipe 11 and the suction pipe 16 of the compressor 1 are connected, The cooling operation in which the refrigerant is circulated from the outdoor heat exchanger 3 to the indoor heat exchanger can be switched. Further, in the air conditioner, the plurality of liquid branch pipes 5 are provided with electric expansion valves EV _{1 to} EV ₃ whose opening degree can be adjusted from the fully closed state to an arbitrary opening degree by a pulse motor, and the liquid pipes 4 are connected to each other. Is provided with a superheat control valve EV _{4 including an} electric expansion valve. And the liquid pipe 4 between the electric expansion valve _EV 1 _{~EV 3} and superheat control valve EV ₄ is receiver 10 is provided. In the figure, 12 and 13 are closing valves, 14 is an accumulator, and 15 is an outdoor fan.

In the air conditioner having the above structure, the electric expansion valve EV ₁ provided corresponding to the operating indoor unit B
To EV ₃ (hereinafter, referred to as a driver's room electric expansion valve EV _x ) is adjusted to an opening according to the number of operating units, and the electric expansion valve E provided corresponding to the stopped indoor unit B is installed.
The openings of V _{1 to} EV ₃ (hereinafter, referred to as stop room electric expansion valve EV _y ) are adjusted to be fully closed during cooling and to have a predetermined small opening during heating. Also, the superheat control valve EV
_The valve ₄ is fully opened during cooling and is opened to a predetermined constant opening during heating. By controlling the electric expansion valves EV _{1 to} EV ₃ in this manner, it is possible to prevent the liquid pool from being generated in the indoor heat exchanger 8 that is stopped, and
The superheat degree of the low-pressure gas refrigerant on the outlet side of the indoor heat exchanger 8 during operation can be controlled during cooling, and the supercooling degree of the high-pressure liquid refrigerant on the outlet side during heating can be controlled.
Further, by providing the superheat control valve EV ₄ , the superheat of the low pressure gas refrigerant in the outdoor heat exchanger 3 during heating can be controlled. With these actions, in the air conditioner, it is possible to simplify the refrigerant circuit and reduce the number of parts, while improving the air conditioning capacity and appropriately distributing the refrigerant.

[0005]

However, in order to obtain a more appropriate refrigerant flow rate of the system, in the conventional air conditioner, the condensing temperature of the indoor heat exchanger 8, the refrigerant temperature near the outlet side thereof, and the compressor 1 are used. A plurality of thermistors for detecting the discharge gas temperature, etc. are provided, and target discharge gas temperature control, cab target supercooling control, heat exchange isothermal control, etc. are performed based on the temperature detected by each of these thermistors. . Therefore, the electric expansion valves EV _{1 to} EV _{3 are}
The opening is thus being controlled in response to changes in load or the like, the proper degree of opening of the stop room electric expansion valve EV _y during heating for opening of the operating room electric expansion valve EV _x These control When the temperature is controlled to increase beyond the range, the indoor heat exchanger 8 that is stopped does not undergo supercooling and is decompressed as it is in the two-phase flow to increase the refrigerant gas flow velocity sound, which causes noise. There was a problem.

The present invention has been made in order to solve the above-mentioned conventional drawbacks, and an object thereof is to perform a heating operation on a user side in a stopped state even if a control for obtaining an appropriate refrigerant flow rate is performed. It is an object of the present invention to provide a heat pump multi-system capable of preventing an increase in noise during use.

[0007]

Therefore, in the heat pump multi-system according to claim 1, a plurality of use side heat exchangers 8 can be connected in parallel to the heat source side heat exchanger 3, and the plurality of use side heat exchangers. 8 through which the refrigerant is circulated from the utilization side heat exchanger 8 to the heat source side heat exchanger 3 through a plurality of liquid branch pipes 5 provided corresponding to the electric expansion valve E.
V _{1 to} EV ₃ are provided, and the electric expansion valves EV _{1 to} EV ₃ are provided corresponding to the stopped use side heat exchanger 8 so as to prevent liquid pooling in the stopped use side heat exchanger 8. A heat pump multi that performs a heating operation by opening the valves to a small opening degree and changing the opening degrees of the electric expansion valves EV _{1 to} EV ₃ provided corresponding to the operating side heat exchanger 8 during operation according to the situation. In the system, the opening degrees of the electric expansion valves EV _{1 to} EV ₃ provided corresponding to the stopped use side heat exchanger 8 are
It is characterized in that a control means 22 for changing the electric expansion valves EV _{1 to} EV ₃ provided corresponding to the operating side heat exchanger 8 is provided.

Further, in the heat pump multi-system of claim 2, the control means 22 has the use side heat exchanger 8 which is stopped.
The opening degree of the electric expansion valves EV _{1 to} EV ₃ provided corresponding to the above is changed with the limit opening degree Q _x that can prevent the pooling of the utilization side heat exchanger 8 being stopped as the lower limit. I am trying.

Further, in the heat pump multi-system according to the _{third aspect} , the opening degree command output means 23 for outputting a command signal corresponding to the opening degree to each of the electric expansion valves EV _{1 to} EV ₃ .
Is provided, and the limit opening Q _x is equal to each of the electric expansion valves EV _{1 to} E _1.
Any of the electric expansion valves EV ₁ provided corresponding to the stopped use side heat exchanger 8 in consideration of the opening degree error existing in V ₃
It is characterized in that it is set as a command signal P _x including the above-mentioned opening degree error so that the opening degree can be secured for EV ₃ to EV ₃ .

[0010]

In the heat pump multi-system according to the above-mentioned claim 1, even if the opening degree of the electric expansion valves EV _{1 to} EV ₃ provided corresponding to the operating side heat exchanger 8 is decreased, the heat pump multi-system is stopped accordingly. Since the opening degrees of the electric expansion valves EV _{1 to} EV ₃ provided corresponding to the use side heat exchanger 8 also decrease, a two-phase flow is generated at the outlet side of the stopped use side heat exchanger 8. Can be suppressed. Therefore, it is possible to prevent an increase in noise on the user side while stopped. In addition, electric expansion valves EV _{1 to} EV provided corresponding to the operating side heat exchanger 8
_The heat exchanger 8 on the use side which is stopped as the opening degree of ₃ increases
Since the opening degrees of the electric expansion valves EV _{1 to} EV ₃ provided corresponding to the above also increase, it is possible to prevent the occurrence of liquid pool in the usage-side heat exchanger 8 that is stopped.

Further, in the heat pump multi-system according to the second aspect, regardless of the opening degree of the electric expansion valves EV _{1 to} EV ₃ provided corresponding to the operating heat exchanger 8 on the operating side, the user side heat when stopped It is possible to ensure the circulation of the refrigerant in the exchanger 8. Therefore, it is possible to reliably prevent the liquid pool while preventing an increase in noise in the usage-side heat exchanger 8 while stopped.

Further, in the heat pump multi-system of the third aspect, since the error existing in each of the electric expansion valves EV _{1 to} EV ₃ is taken into consideration, even if there is a variation in each of the electric expansion valves EV _{1 to} EV ₃ , the circulation of the refrigerant. Can be secured. Therefore, it is possible to perform control that can reliably prevent the liquid pool.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, specific embodiments in which the heat pump multi-system of the present invention is constructed as an air conditioner will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a refrigerant circulation system of the air conditioner. A conventional example with respect to switching between the heating operation in which the refrigerant is circulated from the indoor heat exchanger 8 to the outdoor heat exchanger 3 by switching the configuration of the refrigerant circuit and the four-way switching valve 2 and the cooling operation in which the refrigerant is circulated vice versa Since it is the same as the above, detailed description thereof is omitted here to avoid duplication of description. In the figure, reference numeral 21 is a microcomputer including an input / output interface, a memory, and a CPU for controlling these. This microcomputer 21 controls the electric expansion valve EV in the driver's cab during heating operation.
Control means 22 for performing control for changing the opening degree of the stop room electric expansion valve EV _y according to the situation so that the opening degree of the stop room electric expansion valve EV _y changes in accordance with the change of the opening degree of _x , and this control means. Opening degree command output means 2 that outputs an opening degree instruction signal composed of a pulse signal to each of the electric expansion valves EV _x and EV _y that are operated by a pulse motor in response to a signal from 22.
3 and 3.

FIG. 2 shows the correlation between the opening of the operating room electric expansion valve EV _x and the stop room electric expansion valve EV _y during heating operation and the noise in the room where the indoor heat exchanger 8 is stopped. It is a figure. As shown in the figure, the indoor noise is proportional to the ratio of the opening degrees of the driving room electric expansion valve EV _x and the stop room electric expansion valve EV _y . This is because the amount of heat exchange in the indoor heat exchanger 8 during stop is almost constant due to natural heat dissipation, and therefore the opening degree of the stop room electric expansion valve EV _y relative to the opening degree of the operating room electric expansion valve EV _x is This is because if the ratio is constant, the refrigerant state in front of the stopped room electric expansion valve EV _y will also be constant. The ratio gradually increases, that is, as it goes toward the arrow N shown in the figure, the refrigerant state in front of the stop room electric expansion valve EV _y becomes a two-phase flow, and the indoor noise tends to increase. On the other hand, the ratio is gradually smaller, that is, the refrigerant flow rate in the stop room electric expansion valve EV _y decreases as it goes toward the arrow F, and the liquid tends to accumulate in the indoor heat exchanger 8. Therefore, there is a trade-off between the reduction of noise and the avoidance of liquid pool, but when the indoor noise is set to about 25 dB, both are properly balanced and good results are obtained. However, if the openings of both electric expansion valves EV _x and EV _y are reduced in accordance with the straight line indicating the room noise of 25 dB in FIG. 2, a sufficient refrigerant flow amount cannot be secured in the stop room electric expansion valve EV _y, and the liquid pool is accumulated. It will start to occur. Therefore, the opening degree of the stop chamber electric expansion valve EV _y that can secure a sufficient refrigerant flow rate without such a liquid pool is set as the limit opening degree Q _x . And the electric cab expansion valve E
Even _if the opening degree of V _x becomes smaller than R _{x in the} figure, the opening degree of the stop chamber electric expansion valve EV _y is set to the lower limit of the limit opening Q _x , and the control is not made smaller than this. Therefore, the control means 22 controls the electric expansion valve E in the cab.
The opening degree of V _{x and} the opening degree of the stopped room EV _y are controlled along the line passing through the points A, B, and C in FIG.

By the way, each of the above-mentioned electric expansion valves EV _{1 to} EV ₃
Is configured so that the opening degree can be adjusted from a fully closed state to an arbitrary opening degree by using a pulse motor that rotates a fixed angle with one pulse. FIG. 3 shows a generally commercially available electric expansion valve. When used, each electric expansion valve EV _{1 to} EV
₃ shows the relationship between the number of pulses of the opening degree command signal input to ₃ and the valve opening degree. As shown in the figure, although there is a substantially proportional relationship between the number of pulses and the valve opening, there is a variation having a certain width with respect to the standard value. Therefore, in the opening degree command output means 23 that outputs the opening degree command signal to the electric expansion valves EV _{1 to} EV ₃ , the control means 22 has the limit opening degree Q _x and the electric expansion valves EV _{1 to} EV ₃ .
_In the case of controlling to open any one of the valve Nos. 3 and 3, the electric expansion valves EV ₁ to EV ₁ that respond to the opening command signal having the number of pulses corresponding to P _x in FIG. Also for the EV ₃ , an opening degree command signal composed of the number of pulses capable of ensuring the limit opening degree Q _x is output. In the figure, the limit opening Q _x is about 0.3.
Although it is shown as the valve opening degree of (Nm ³ / h), it is needless to say that it is not limited to such a value in other embodiments.

In the air conditioner configured as described above, during heating operation, the opening degree of the stop room electric expansion valve EV _y opened to a small opening degree is proportional to the opening degree of the driving room electric expansion valve EV _x. The control means 22 is provided to control so as to change. Therefore, the state of the refrigerant in front of the stop room electric expansion valve EV _y is constant and no two-phase flow is generated, so that it is possible to prevent an increase in room noise, and at the same time, to open the operating room electric expansion valve EV _x . There is no possibility that the opening degree of the stopped room electric expansion valve EV _y becomes too small as compared with the degree and the liquid pool is generated in the indoor heat exchanger 8. Further, since the opening degree of the stop room electric expansion valve EV _y is changed with the limit opening degree Q _x as the lower limit, it is possible to ensure the circulation of the refrigerant in the indoor heat exchanger 8 during the stop, and thus to reliably collect the liquid pool. Can be prevented. Further, in response to the control in which the stop room electric expansion valve EV _y is set to the limit opening Q _x by the control means 22, the opening instruction output means 23 outputs an opening instruction signal composed of the pulse number P _{x in} consideration of an error. Therefore, each of the electric expansion valves EV _{1 to} EV
Even if there is a variation in ₃ , the above-mentioned limit opening Q _x can be secured, and the liquid pool can be reliably prevented.

Although the specific embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the present invention. For example, in this embodiment, an example in which it is configured as an air conditioner has been shown, but it may be applied to other heat pump multi-systems having a heat exchanger for hot water supply, bath heating, etc. as a heat exchanger on the other side.

[0019]

According to the heat pump multi-system of the above-mentioned claim 1, even if the opening degree of the electric expansion valve provided corresponding to the operating heat exchanger in operation is reduced, the operating heat in the stopped state is accordingly reduced. Since the opening degree of the electric expansion valve provided corresponding to the exchanger is also reduced, it is possible to suppress the generation of the two-phase flow on the outlet side of the utilization side heat exchanger which is stopped.
Therefore, it is possible to prevent an increase in noise on the user side while stopped. Further, as the opening degree of the electric expansion valve provided corresponding to the operating side heat exchanger in operation increases, the opening degree of the electric expansion valve provided corresponding to the stopped operating side heat exchanger also increases. Therefore, it is possible to prevent the liquid pool from being generated in the utilization side heat exchanger that is stopped.

Further, in the heat pump multi-system according to the second aspect of the invention, regardless of the opening degree of the electric expansion valve provided corresponding to the operating side heat exchanger in operation, the flow of the refrigerant in the stopping side heat exchanger is stopped. Can be secured. Therefore, it is possible to reliably prevent the liquid pool while preventing an increase in noise in the usage side heat exchanger that is stopped.

Further, in the heat pump multi-system according to the third aspect, since the error existing in each electric expansion valve is taken into consideration, it becomes possible to secure the circulation of the refrigerant even if there is a variation in each electric expansion valve. Therefore, it is possible to perform control that can reliably prevent the liquid pool.

[Brief description of drawings]

FIG. 1 is a refrigerant circulation system diagram in an embodiment in which the present invention is configured as an air conditioner.

FIG. 2 is a characteristic diagram showing the relationship between the opening degree of the electric expansion valve and room noise in the above embodiment.

FIG. 3 is an opening characteristic diagram of the electric expansion valve in the above embodiment.

[Explanation of symbols]

3 outdoor heat exchanger 5 liquid branch pipe 8 indoor heat exchanger 22 the control means 23 opening command output means Q _x limit opening P _x opening command signal EV ₁ ~EV ₃ electric expansion valve

Claims (3)

[Claims] 1. A plurality of use side heat exchangers (8) can be connected in parallel to a heat source side heat exchanger (3), and the heat source side heat exchangers (3) are provided corresponding to the plurality of use side heat exchangers (8). Refrigerant is circulated from the utilization side heat exchanger (8) to the heat source side heat exchanger (3) through the plurality of liquid branch pipes (5), and the electric expansion valve (EV _{1 is connected to the} plurality of liquid branch pipes (5). ~ EV ₃ ) respectively, and an electric expansion valve (EV ₁ ) provided corresponding to the stopped use side heat exchanger (8) so as to prevent pooling in the stopped use side heat exchanger (8). ~EV ₃₎ while opening the small opening degree, in accordance with the opening degree of the electronic expansion valve provided corresponding to the usage-side heat exchanger during operation _{(8) (EV 1 ~EV 3} ) the situation In a heat pump multi-system that performs heating operation by changing it, it is provided corresponding to the stopped heat exchanger (8) on the use side. Electric expansion valve opening degree of the _(EV 1 _{~EV 3),} in response to changes in the electric expansion valve provided corresponding to the usage-side heat exchanger during operation _{(8) (EV 1 ~EV 3} ) change was A heat pump multi-system comprising a control means (22) for controlling the heat pump. 2. The electric expansion valve (E), wherein the control means (22) is provided so as to correspond to a stopped use side heat exchanger (8).
The opening degree of V _{1 to} EV ₃ ) is changed with a limit opening degree (Q _x ) that can prevent liquid pooling of the utilization side heat exchanger (8) being stopped as a lower limit. Heat pump multi system. _3. The opening degree command output means (23) for outputting a command signal according to the opening degree of each of the electric expansion valves (EV _{1 to} EV ₃ ) is provided, and the limit opening degree (Q _x ) is provided. , taking into account the degree of opening errors existing in the electric expansion valve _(EV 1 ~EV _3), one of the electric expansion valve provided corresponding to the usage-side heat exchanger in the stop (8) (EV ₁ ~ The heat pump multi-system according to claim 2, wherein a command signal (P _x ) including the opening error is set so that the opening can be secured even for EV ₃ ).