JPS5833500Y2 - air conditioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat pump type air conditioner capable of heating and cooling operation, and particularly relates to improvement of a refrigeration cycle for heating operation.

BACKGROUND ART In recent years, heat pump type air conditioners, which can perform cooling operation and heating operation simply by switching a switch, have been increasingly used.

In Japan's general climate (for example, 0°C in winter and 30"C in summer), the cooling/heating capacity ratio is: cooling capacity is 1, heating capacity is 1.
Approximately 5 is required.

However, when using a compressor whose capacity is not variable,
Generally, the above-mentioned cooling/heating capacity ratio is such that the heating capacity is only about 1.2 for the cooling capacity of 1 due to the design of the refrigeration cycle, and if the capacity of the compressor is matched to the cooling capacity, the heating capacity will be insufficient.

On the other hand, if you match the capacity of the compressor to the heating capacity, the capacity of the compressor will increase too much during the cooling operation, which will not only cause you to get too cold, but will also have a negative impact on your body, as well as 0NOF.
There are inconveniences such as loss of power due to F action and reduced durability of the compressor due to shock at startup due to sudden NOFF action.In addition, conventional auxiliary electric heating equipment is used to compensate for the lack of heating capacity. There are many devices that have

In this case, a relatively small-capacity compressor is sufficient, so there is no problem with efficiency during cooling, but when heating, the input and current increase due to the auxiliary electric heating device, and the power supply capacity must be increased, and safety devices must be installed. There are many parts that need to be replaced, and it is inevitable that the equipment will become larger.

Furthermore, in terms of thermal efficiency, if the value of the auxiliary electric heating device is 1, that of the refrigeration cycle is 2 to 2.5, so the use of the auxiliary electric heating device during heating has a lower thermal efficiency than that of the refrigeration cycle. bad.

Therefore, in order to increase the heating capacity, it may be possible to adopt a gas injection method in which the gas refrigerant separated by the gas-liquid separator during heating is introduced into the cylinder during the compression stroke of the compressor.

However, according to the above-mentioned gas injection method, since the amount of work of the compressor is large, the discharge temperature of the compressor rises, especially during heating overload, and the compressor motor overheats, resulting in burnout of the motor coil. there were.

The present invention was developed based on the above circumstances, and its purpose is to transfer gas refrigerant separated by a gas-liquid separator during heating into a cylinder during the compression stroke of a compressor in order to increase heating capacity. The purpose of the present invention is to provide an air conditioner that employs a gas injection method and that prevents a compressor from overheating during heating overload.

An embodiment of the present invention will be described below based on the drawings.

Figure 1 shows the configuration of the refrigeration cycle.
is a compressor, 2 is a four-way valve, 3 is an outdoor heat exchanger, 4 is a check valve, 5 is a gas-liquid separator, 6 is a capillary tube which is a pressure reducing device, and 7 is an indoor heat exchanger. , these are communicated via refrigerant pipes in the above numerical order to constitute a heat pump type refrigeration cycle.

Further, a branching device 8 is provided between the check valve 4 and the gas-liquid separator 5.

8a is a liquid refrigerant introduction pipe separated by the gas-liquid separator 5, and the liquid refrigerant introduction pipe 8a is connected via an auxiliary expansion valve 9 to a conduction pipe 10.

Further, reference numeral 8b denotes a gas refrigerant introduction pipe separated by the gas-liquid separator 5, and the gas refrigerant introduction pipe 8b is provided with a gas injection circuit 11, which will be described later.

That is, this gas injection circuit 11 introduces the gas refrigerant separated by the gas-liquid separator 5 into the cylinder of the compression stroke of the compressor 1, and one end is connected to the gas refrigerant introduction pipe 8b, and a heating An electromagnetic opening/closing valve 12 is provided with a heat sensing part 12a that senses the discharge side temperature of the compressor 1 during operation, and when this senses a predetermined temperature or higher, it closes during heating overload such as when the outside temperature is high, and is normally open. A gas injection pipe 13 is provided, and the other end thereof communicates with a cylinder (not shown) of the compressor 1.

Generally, as the load on the compressor increases, the discharge temperature of the compressor increases as a result, and the heating overload detection means detects the discharge temperature of the compressor and the outside air temperature.

Furthermore, as the outside temperature increases, the suction pressure of the compressor also increases, and the load on the compressor also increases.

Next, the operation of the above embodiment will be explained.

First, to explain the cooling operation, the refrigerant discharged from the compressor 1 is guided to the outdoor heat exchanger 3 via the four-way valve 2, as shown by the broken line arrow in the figure, and is condensed and liquefied.

Furthermore, it is guided to the indoor heat exchanger 7 via the check valve 4, the gas-liquid separator 5, and the capillary tube 6, and can perform a cooling action by removing the latent heat of vaporization from the air-conditioned room.

At this time, the electromagnetic on-off valve 12 is always closed and the gas injection circuit 11 does not perform any operation.

Next, explaining the heating operation, the refrigerant discharged from the compressor 1 is guided to the indoor heat exchanger 7 via the four-way valve 2 as shown by the solid line arrow in the figure, and the condensed heat is released into the air-conditioned room. A heating effect can be performed.

The condensed refrigerant is led to the gas-liquid separator 5 via the capillary tube 6, and the gas component is separated from the liquid refrigerant.

After separation, the liquid refrigerant is guided from the liquid refrigerant introduction pipe 8a to the conduit pipe 10, further expanded by the auxiliary expansion valve 9, evaporated by the outdoor heat exchanger 3, and sucked into the compressor 1.

On the other hand, the gas refrigerant separated by the gas-liquid separator 5 is guided to the gas injection circuit 11, and is sucked into the cylinder of the compressor 1 during the compression stroke via the electromagnetic on-off valve 12, thereby improving the heating capacity. .

Therefore, the refrigeration cycle in this state can be explained from the Mollier diagram shown in FIG.

That is, the state change in a normal refrigeration cycle is A-B-C
-D, AB represents a compression stroke, BC represents a heat radiation stroke, CD represents an expansion stroke, and DA represents an endothermic stroke.

Therefore, in a normal refrigeration cycle, if loss is ignored, the amount of heat absorbed from the outside air Q1, the amount of work Qcomp of the compressor, and the amount of heat released (heating capacity) Q2 have the following relationship.

Q 2 = Q 1 +Q comp ■
In addition, the state changes of the gas injection cycle (hereinafter referred to as "cass injection cycle") in which the gas refrigerant separated by the gas-liquid separator is introduced into the cylinder during the compression stroke of the compressor 1 are as follows: A-A'~)l' -BC-E-F-G, where A-A"-H'-B is a compression stroke, B-C is a heat radiation stroke, C-E-F-G is an expansion stroke, and G-A is an endothermic stroke. are shown respectively.

That is, the refrigerant is separated into liquid and gas at point E (point F is liquid,
Indicates a hot gas refrigerant.

) Liquid cooling expands at 0 points and 1.

As a result, compared to a normal refrigeration cycle, the amount of heat absorbed from the outside air increases by the enthalpy difference between G and D.

On the other hand, the gas refrigerant separated at point E is guided into the cylinder during the compression stroke.

As a result, the injected gas is the gas at point H, which is lower in temperature than the gas refrigerant in the compression process from point A, so that the gas in the cylinder of compressor 1 is mixed with the gas at point H, which is the gas in the cylinder of compressor 1 at the polygonal line (A'-H' ) It will be cooled at t.

Therefore, in the gas injection cycle, if losses are ignored, the amount of heat absorbed from the outside air is Q1t, and the work of the compressor is Q'
comp, heat radiation amount r heating capacity) Q2' have the following relationship.

Q2' = Q1' + Qc'o m p
■Then, when comparing the [F] formula of a normal refrigeration cycle and the gas injection cycle formula 0, Ql'
>Ql ■', 'The amount of heat absorbed from the outside air increases by the enthalpy difference between G and D.

Also Q'c omp>Qc omp ■°, °
The compressor also does more work to compress the gas refrigerant separated by the gas-liquid separator.

Therefore, from equation (2), Q' 2 >Q 2, and the heating capacity of the gas injection cycle is greater than that of the normal refrigeration cycle.

This improves the capacity of the refrigeration cycle itself, making it more efficient than the electric heater conventionally used as an auxiliary heat source.

The above increase in heating capacity is due to an increase in the amount of gas refrigerant separated by the gas-liquid separator and circulated by the compressor from the heat radiation side.

That is, the heating capacity is expressed as the product of the amount of refrigerant circulating in the refrigeration cycle and the enthalpy difference between the inlet and outlet of the condenser.

The enthalpy at the condenser inlet is the refrigerating temperature of the discharge gas from the compressor (the enthalpy at point B in Figure 2...ignoring the loss, the enthalpy at the condenser inlet is the enthalpy of the discharge gas refrigerant temperature), and the enthalpy at the condenser outlet is the enthalpy at the condenser inlet. is determined by the temperature of the liquid refrigerant at the condenser outlet (enthalpy at point C in Figure 2), so it is safe to assume that the enthalpy at point B and C in Figure 2 in a normal refrigeration cycle and in gas injection are the same.

In addition, during heating operation, if the heat sensing part 12a detects a temperature higher than a predetermined temperature, the electromagnetic on-off valve 12
compressor 1 for gas which is closed and separated by gas-liquid separator 5
This prevents electrical conduction and prevents the compressor 1 from overheating.

As explained above, according to the present invention, in a device equipped with a heat pump type refrigeration cycle, a gas-liquid separator provided between an outdoor heat exchanger and a pressure reducing device, a gas-liquid separator and a compressor are provided. The heating capacity can be increased by providing a gas injection circuit that is connected to the air conditioner via an on-off valve and that guides the gas refrigerant separated by the gas-liquid separator into the cylinder during the compression stroke of the compressor. .

In addition, the on-off valve is closed to prevent the gas refrigerant separated by the gas-liquid separator from being introduced into the cylinder in the compression stroke of the compressor when there is an overload of heating due to high discharge temperature or high outside temperature. This provides effects such as being able to prevent the compressor from overheating.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a block diagram of a refrigeration cycle, and FIG. 2 is a Mollier diagram. DESCRIPTION OF SYMBOLS 1... Compressor, 3... Outdoor heat exchanger, 5... Gas-liquid separator, 6... Ball reduction device, 11... Gas injection circuit.

Claims (1)

[Scope of utility model registration request] In a heat pump type refrigeration cycle in which a compressor, a four-way valve, an outdoor heat exchanger, a pressure reducing device, and an indoor heat exchanger are connected in sequence, a heat pump type refrigeration cycle is installed between the outdoor heat exchanger and the pressure reducing device. A gas-liquid separator connected to the compressor via an on-off valve, and a gas that guides the gas refrigerant separated by the gas-liquid separator into the cylinder during the compression stroke of the compressor. The injection circuit is equipped with an injection circuit that opens and closes to prevent the gas refrigerant separated by the gas-liquid separator from being introduced into the cylinder of the compression stroke of the compressor during heating overload such as when the discharge temperature is high or the outside temperature is high. An air conditioner characterized by closing a valve.