JPS6036844Y2 - Heat pump refrigeration equipment - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a heat pump type refrigeration system that enables pump-down operation during the heating cycle, and is particularly designed to prevent liquid backflow during pump-down operation.

In this type of heat pump type refrigeration equipment, during maintenance inspection or refrigerant replenishment, the outlet side of the liquid receiver is closed with a closing valve while the refrigeration equipment is operated in the heating cycle to receive the refrigerant in the refrigerant circuit. A so-called pump-down operation is performed to collect liquid refrigerant in the container, but at this time, liquid refrigerant also collects in the heat exchanger upstream of the refrigerant receiver, so it is difficult to defrost when pumping down during heating operation, especially in winter. When operation begins, a so-called liquid back phenomenon occurs in which the liquid refrigerant accumulated in the heat exchanger, which acts as a condenser during heating operation and an evaporator during cooling (defrosting) operation, flows directly back to the suction side of the compressor. Since there is a risk of damage to the pump, it is necessary to avoid entering defrost operation during pump down operation.

However, in conventional heat pump refrigeration equipment of this type, no means was provided to prevent defrosting operation during pump-down operation, so the heating cycle was switched to the defrosting cycle during pump-down operation. There was a problem that a liquid back phenomenon occurred and the compressor was damaged.

The present invention was made in order to improve the above-mentioned problems during pump-down operation of conventional heat pump type refrigeration equipment, and the defrost switch circuit in the control electric circuit of the refrigeration equipment is provided with pump-down operation. It is an object of the present invention to provide a heat pump type refrigeration device which prevents liquid back phenomenon during pump down operation by attaching a control member to de-energize the defrosting switch circuit at times. It is.

Hereinafter, the heat pump type refrigeration system of the present invention will be explained using the heat pump type chiller shown in Fig. 1 as an example.
The heat pump chiller shown in the figure has a compressor 1, a four-way switching valve 9
, heat source side heat exchanger 2, parallel circuit 17 of heating expansion valve 5 and check valve 13, closing valve 7, liquid receiver 4, parallel circuit 18 of cooling expansion valve 6 and check valve 14, hot and cold water piping A refrigerant circulation circuit 10 is constructed by sequentially connecting user-side heat exchangers (water heat exchangers) 3 having 8 and 8 in series, and the refrigerant gas discharged from the compressor 1 passes through the four-way switching valve 9. The refrigerant circulation circuit 10 is reversibly circulated through the refrigerant circuit 10, and the four-way switching valve 9 is switched during heating operation to supply high-temperature discharge gas to the heat source side heat exchanger 2 to defrost it. .

This heat pump chiller is controlled by an electric circuit as shown in FIG.

That is, in the electric circuit shown in FIG.
When the heating switch 15a is turned on, the relay 25 is energized via the temperature regulator 24 having the detection part 24a attached to the cold/hot water pipe 8, and its contact 28 is turned on, and the compressor motor 11 and outdoor fan motor are turned on. 12, the compressor 1 and the outdoor fan 27 are operated.

At this time, the solenoid 16 that switches and drives the four-way switching valve 9 is in a de-energized state, and the four-way switching valve 9 is switched during the heating cycle (first
In the refrigerant circuit shown in the figure, the refrigerant flows in the direction indicated by the dashed arrow).

When a predetermined amount of frost forms on the heat source side heat exchanger 2 during heating operation, a defrost switch circuit A consisting of a defrost switch 20, a timer 21, an auxiliary relay 22, and wiring 30.31 is activated.
When the defrost switch 20 is turned on, the auxiliary relay 2
2 and turns on the normally open contact 23.

As a result, when the solenoid 16 is energized, the four-way switching valve 9
is switched to the defrosting cycle (cooling cycle) side, high temperature discharge gas is supplied to the heat source side heat exchanger 2, and defrosting is performed using the heat.

During cooling operation, when the cooling switch 15b is turned ON, the relay 25 and solenoid 16 are energized, and the four-way selector valve 9 is held on the side of the cooling cycle (refrigerant flows in the direction shown by the solid arrow in the refrigerant circuit in Figure 1). At the same time, the compressor motor 11 and the outdoor fan motor 12 are energized.

Next, when performing a pump-down operation in the refrigerant circuit of FIG. A control member 26 (specifically, a manual switch) for de-energizing the defrosting switch circuit A is connected in series to the wiring 30 between the heating switch 15a and the heating switch 15a, and the control member 26 is turned off. By doing so, the defrosting operation auxiliary relay 22 is not energized regardless of whether the defrosting switch 20 is turned on or off.

That is, during pump-down operation, the pressure of the heat source side heat exchanger 2 becomes extremely low, which may cause the defrost switch 20 to turn on. Even in such a case, the control member 26 (manual switch) is turned on in the illustrated refrigerant circuit. ) is opened, the switching from the heating cycle to the defrosting cycle is prevented,
That is, the four-way switching valve 9 does not switch, and therefore, liquid backflow to the compressor 1 due to switching from the heating cycle to the defrosting cycle is prevented.

In the above embodiment, the closing valve 7 was interposed in the piping, but in other embodiments, the heating expansion valve 5 is provided with a closing function, and the heating expansion valve 5 is
The shutoff valve 7 may also be used as the shutoff valve 7. In this case, the shutoff valve 7 becomes unnecessary and the refrigerant circuit becomes simple.

Further, although a manual switch has been described as the control member 26, instead of this, the wiring 30 and the defrosting switch 20 can be connected via a connecting terminal, and the wiring 30 can be directly disconnected from this connecting terminal. It's okay.

In this case, a manual switch is not required. In addition, although the control member 26 has been described as being interposed in the wiring 30, this intervening position is different from the defrosting switch 20 and the auxiliary relay 22.
It may be between the wire 31 or the wiring 31 side.

As is clear from the description of the embodiments above, the heat pump type refrigeration system of the present invention operates the pump in a heating cycle with the closing valve interposed between the heat source side heat exchanger and the liquid receiver closed. In addition to enabling down-operation, a control member is attached to the defrost switch circuit in the control electric circuit of the refrigeration system to de-energize the defrost switch circuit during the pump-down operation. There is no switching from the heating cycle to the defrosting cycle during pump down operation, and therefore there is an effect of reliably preventing liquid backflow to the compressor.

[Brief explanation of drawings]

FIG. 1 is a refrigerant circuit diagram of a heat pump type refrigeration system according to an embodiment of the present invention, and FIG. 2 is an electric circuit diagram for controlling the refrigeration system of FIG. 1. 1...Compressor, 2...Heat source side heat exchanger, 3...Using side heat exchanger, 4...Liquid receiver, 7... ... Closing valve, 9 ... Four-way switching valve, 16 ... Four-way switching valve solenoid, 20 ... Defrost switch, 26 ...・Control components.

Claims (1)

[Scope of utility model registration request] Compressor 1, four-way switching valve 9, heat source side heat exchanger 2, liquid receiver 4
, the user-side heat exchangers 3 are successively connected in series, and during heating operation, the four-way switching valve 9 is switched to supply high-temperature discharge gas to the heat source-side heat exchanger 2, and the heat is used to switch the heat source-side heat exchanger 2. 2, and the heat source side heat exchanger 2
A closing valve 7 is interposed between the liquid receiver 4 and the liquid receiver 4, and by operating in a heating cycle with the closing valve 7 closed, a pump-down operation can be performed in which the refrigerant is stored in the liquid receiver 4. In the heat pump type refrigeration apparatus, a control member 26 is attached to the defrost switch circuit A in the control electric circuit of the heat pump type refrigeration apparatus to de-energize the defrost switch circuit A during the pump down operation. A heat pump type refrigeration system that is characterized by: