JPS5995351A - Capacity control refrigerating circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention uses a reversible expansion valve as an expansion valve in a refrigeration cycle in which capacity control of a compressor is variable using an inverter or the like, and the amount of Sys-74 heat can be adjusted arbitrarily using an electronic signal. This invention relates to a capacity control refrigeration circuit that can be set.

FIG. 1 is a schematic diagram showing a refrigerant flow path to a conventional expansion valve. In Figure 1 of Figure 1, 1 company expansion valves and 2 to 5 are each check valves. The direction is shown by a solid line.

In FIG. 1, the flow direction of the refrigerant flowing into the expansion valve l is defined.

By the way, conventionally, a temperature-type automatic expansion valve is used as an expansion valve in this type of refrigeration cycle, but suit 4
By touching the thermosensitive cylinder to the piping that controls the amount of heat,
The response is slow because temperature changes are converted to pressure changes. For this reason, it is not possible to follow sudden changes in load and compression operation capacity, and has the disadvantage of being prone to liquid puddles and hunting.

In addition, since the flow of refrigerant is unidirectional, in devices that perform cooling and heating such as heat pumps, the direction of flow of refrigerant is reversed, so a circuit that keeps the direction of refrigerant input to the expansion valve constant is required. It was necessary to form.

Furthermore, since the amount of superheat is not directly detected, such as through a thermosensor that is activated by the expansion of gas or liquid, the amount of superheat can be controlled at will to suit the operating conditions of the air conditioner. It was impossible to do so.

In addition, conventional electric expansion valves that detect the amount of superheat as a control signal detect the temperature at the evaporator inlet or intermediate part (Te) and the compressor inlet temperature (Ti). The superheat amount (SH) is SH= Ti
-Te, but there is a pressure drop at the evaporator inlet, middle part, and compressor inlet.

It has been impossible to accurately detect the amount of superheat because the amount of this decrease varies depending on the air conditions and the operating capacity of the compressor. Furthermore, some systems have installed a pressure sensor and a temperature sensor at the inlet of the compressor to detect the amount of superheat, but this has the disadvantage that the pressure sensor is expensive.

Therefore, in this invention, the throttling operation of the expansion valve can be performed in the same way even if the direction of refrigerant inflow is reversed, and when controlling the capacity of the compressor, it is not limited to constant superheat, but can be controlled at any time. An object of the present invention is to provide a capacity control refrigeration circuit equipped with a controller that can detect the amount of soot/mother heat and control the opening degree of an expansion valve so that the amount of soot/mother heat can be changed.

Embodiments of the capacity control refrigeration circuit of the present invention will be described below with reference to the drawings. FIG. 2 is a circuit diagram of a refrigeration cycle according to one embodiment. In this FIG. 2, A indicates an indoor unit, and B indicates an outdoor unit.

First, in the outdoor unit (B), 11 is a compressor whose capacity can be controlled. This compressor 11 is connected to an outdoor heat exchanger 13 through a four-way valve 12 for switching between air conditioning and heating.

This outdoor heat exchanger 13 includes a distributor 14a,
14b to the electric reversible expansion valve 15, the electric reversible expansion valve 15 is connected to the indoor side of the indoor/outdoor unit A,
It is connected to a heat exchanger 16.

The indoor heat exchanger 16 is connected to an accumulator 17 through the four-way valve 12, and the accumulator 17 is connected to the compressor 11.

Near the refrigerant suction side of this compressor 11, there is a
A pressure sensor 19 is also provided.

The temperature sensor 18 detects the suction temperature of the refrigerant of the compressor 11, and its detection output is sent to the controller 20. Further, the pressure sensor 19 detects the suction pressure of the refrigerant of the compressor 11, and the detected output is also sent to the controller 20 (1).

The controller 20 receives these detection outputs and controls the opening and closing of the electric reversible expansion valve 15.

Next, the operation of the capacity control refrigeration circuit of the present invention configured as above will be explained. The high-temperature, high-pressure refrigerant gas compressed by the compressor 11 flows into the outdoor heat exchanger 13 during cooling operation through the four-way valve 12, and the refrigerant liquid condensed and liquefied there passes through distributors 14a and 14b and is then supplied with electricity. The refrigerant liquid reaches the reversible expansion valve 15 and adiabatically expands to become a low-pressure, low-temperature two-phase refrigerant υ.In the indoor heat exchanger 16, the refrigerant liquid absorbs heat from the surroundings and evaporates, becoming a gas and opening the four-way valve 12. and flows into the accumulator 17.

From there, the refrigerant gas passes through the suction pipe and is sucked into the compressor 11, where the refrigerant is compressed and circulated through the system again.

The pressure P of this suction refrigerant is detected by the pressure sensor 19, the temperature T is detected by the temperature sensor 18, and the controller 20
sent to.

In the controller 20, superheat is detected from these two detection outputs.
The amount SH is calculated, and an expansion valve opening signal is sent to the electric expansion valve 15 in accordance with the value of the superheat amount.

In the capacity control refrigeration circuit configured in this manner, during heating operation, the flow path of the four-way valve 12 is switched υ, and the flow path of the compressor 1 is switched.
The high-temperature, high-pressure refrigerant gas compressed in step 1 flows into the indoor heat exchanger 16 via the four-way valve 12, is liquefied into a low-temperature, high-pressure refrigerant liquid, and flows into the electric reversible expansion valve 15 from the opposite direction.
The refrigerant expands into a low-temperature, low-pressure two-phase refrigerant and passes through the distributor 14.
a, 14b, evaporates in the outdoor heat exchanger 13, enters the accumulator 17 again via the four-way valve 12, and enters the compressor 1.
1 is inhaled.

By making the inlet and outlet of the electric reversible expansion valve reversible in this way, the refrigeration circuit itself can be simplified and its reliability can be improved.

Also, capacity characteristics and efficiency during heating operation (cop~EER)
) is shown in Figure 3. FIG. 3 shows the relationship between the heating capacity Q and the superheat amount SH, and the relationship between the coefficient of performance COP and the superheat amount SH.

As can be seen from FIG. 3, the amount of superheat, which maximizes the heating capacity Q, and the amount of super heat, which maximizes the heating capacity Q, do not match and differ. For example, if you want to raise the room temperature quickly by giving priority to heating capacity, increase the amount of super heat, and when the room temperature approaches the set temperature, give priority to performance efficiency COP and increase the amount of super heat to save energy. Comfort and energy savings can be achieved by controlling the size of the space.

As described above, according to the capacity control refrigeration circuit of the present invention,
The pressure and temperature of the refrigerant at the inlet of the compressor are detected, and the value of the system superheat amount is calculated based on the detection signal.The opening of the air-type reversible expansion valve is controlled based on the calculation result, and the compression is performed during heating operation. The high-temperature, high-pressure refrigerant gas compressed by the machine flows into the indoor heat exchanger, where it is liquefied into a low-temperature, high-pressure refrigerant liquid, which flows into the electric reversible expansion valve from the opposite direction.
Since the phase refrigerant is expanded, energy-saving operation is possible.
It will also be possible to improve controllability, such as driving with comfort in mind.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a conventional liquid path for refrigerant to an expansion valve, Fig. 2 is a refrigeration circuit diagram showing an embodiment of the capacity control refrigeration circuit of the present invention, and Fig. 3 is a diagram of a high volume control refrigeration circuit. It is a characteristic curve diagram of heating capacity and coefficient of performance for super heat. DESCRIPTION OF SYMBOLS 11... Compressor, 12... Four-way valve, 13... Outdoor heat exchanger, 14a, 14b... Distributor, 15... Electric reversible expansion valve, 16... Indoor heat exchanger 17...Accumulator, 18...Temperature sensor, 19...Pressure sensor, 20...Controller. Agent Makoto Kuzuno - Fig. 1 Fig. 2 Fig. 3 Fig. 3 '1) 1 - Director-General of the Agency 1, Indication of matter f'l fll; IG (j, 1982)
-205015 No. 2 Zuko Akira's 21 (4, Volume control refrigeration circuit 3, 'f'mountain' 1.) 5, Claims column 6 of the symmetrical specification of the amendment, Contents of the amendment (1) Specification 7. List of Attached Documents (1) Amended Claims 1 or more 2 Claims: Capacity controllable compressor, outdoor heat exchanger , in a refrigeration circuit having an indoor heat exchanger, a four-way valve for switching between air conditioning and heating, and an accumulator, means for detecting the total amount of superheat of the refrigerant at the inlet of the compressor, and issuing a command based on the amount of superheat detected by the means. 1. A capacity control refrigeration circuit characterized by comprising: a controller for generating air, and an electric expansion valve that can adjust the opening degree of the expansion valve based on commands from the controller and has a reversible opening/outlet of a cold.

Claims (1)

[Claims] In a refrigeration circuit having a capacity controllable compressor, an outdoor heat exchanger, an indoor heat exchanger, a four-way valve for switching between air conditioning and heating, and an accumulator, means for detecting the amount of superheat of the refrigerant at the inlet of the compressor. and a controller that issues a command based on the amount of superheat detected by this means; and a controller that can adjust the opening degree of the expansion valve based on the command of the controller, and that also controls the amount of heat exchanger from the compressor to the indoor heat exchanger during heating operation. 1. A capacity control refrigeration circuit characterized by comprising a reversible electric expansion valve at an inlet and outlet through which high-temperature, high-pressure refrigerant gas flows in the opposite direction.