JPH0156351B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an air conditioner using an electrically operated refrigerant control valve, and in particular to an air conditioner using an electrically operated refrigerant control valve. This invention relates to a flow rate control device.

(Prior art) Conventional refrigerant flow control for air conditioners is generally performed by, for example, controlling the valve opening of a temperature-sensitive automatic expansion valve so that the degree of superheating of the refrigerant in the evaporator remains constant. is automatically adjusted. (Published by the Japan Refrigeration Association, Refrigeration and Air Conditioning Handbook New Edition 4th Edition Basic Edition, p. 472, Figures 11 and 25, published on May 30, 1980) This constant superheating control allows heat exchange when the evaporation temperature is given. The capacity of the compressor is fixed-value control, so if you want to perform fine-grained capacity control to maintain a constant room temperature in cases where the air conditioning load fluctuates widely, you must first perform capacity control on the compressor side. Normally, the results are reflected on the heat exchanger side.

However, this requires installing an unloader mechanism in the compressor or controlling the rotation of the compressor motor using an inverter, etc., which requires a device with a complicated structure, which increases costs and requires complicated control. Nakatsuta.

On the other hand, there is another type of refrigerant flow rate control that automatically adjusts the valve opening of the subcooling control valve so that the degree of subcooling of the refrigerant in the condenser remains constant (Jikkosho
46-26920), but this also has the same problem.

Therefore, from the viewpoint of improving room temperature controllability, an electrically operated refrigerant control valve is used as a refrigerant flow control means, that is, an electrically operated expansion valve is used during cooling.
During heating, each of the refrigerant control valves functions as a supercooling control valve, and the opening degree of the refrigerant control valve is proportionally controlled using the set temperature and the temperature of the air sucked into the user-side coil as control input elements so that the room temperature remains constant. One possible method is to do so.

An electrically operated refrigerant control valve is an expansion valve that has an electric device such as a stepping motor or an electromagnetic plunger as a driving element and can adjust the valve opening according to the amount of electricity input. It is thought that its popularity will increase in the future because the temperature can be easily adjusted.

(Problems to be Solved by the Invention) However, with this electrically actuated refrigerant control valve, when trying to perform efficient operation by maximizing the heat exchange capacity of the user coil, The state of the refrigerant at the outlet often becomes moist during cooling operation and fluffy during heating operation, resulting in unfavorable operational results.

Note that the above-mentioned "wetness" includes not only a state in which the refrigerant is in a gas-liquid mixed state but also a state in which the degree of superheat is lower than a predetermined value (for example, 5° C.). Furthermore, the above-mentioned "flash" includes not only the gas-liquid mixed state of the refrigerant but also the state where the degree of supercooling is lower than a predetermined value (for example, 5° C.).

This is because the method of controlling the amount of refrigerant based on the difference between the set temperature and the suction temperature operates the opening degree of the refrigerant control valve according to the required capacity, so the heat exchange processing capacity does not exceed the required capacity. For example, in the case of cooling operation, if the set value is set quite low, the refrigerant control valve will operate to supply refrigerant in excess of its processing capacity, and in this case, it will cause damp operation. means state.

However, as is well known, when the outlet of the user-side coil is in a wet region or a flash region, the cooling capacity or heating capacity is almost constant and the valve opening degree is controlled, which is meaningless in terms of capacity adjustment.

On the other hand, if the coil on the user side becomes damp (in the case of cooling), to prevent damp compression at the compressor suction section,
On the contrary, it was necessary to add a hot gas bypass circuit and use a compressor operating capacity control mechanism.
This not only increases the cost of the device, but also causes significant disadvantages in terms of control reliability and energy saving.

On the other hand, it is similarly undesirable to bring the user-side coil into a flashing state at the outlet during heating operation, as this may result in refrigerant gas being mixed into the liquid pipe, resulting in an increase in the discharge pressure.

In order to solve these problems, the present invention has been made to solve the above-mentioned drawbacks, and it is an object of the present invention to determine the state of the refrigerant at the outlet of the coil on the user side depending on the temperature as well as the temperature of the fluid such as air or water. When cooling, the outlet is always close to the boundary with the wet and dry conditions, or during heating, the outlet is sealed close to the boundary with the flash. By controlling the opening degree of the operating refrigerant control valve, the outlet of the coil on the user side is kept in an appropriate refrigerant state, thereby improving room temperature controllability while achieving low cost and energy savings. It is something to do.

(Means for Solving the Problems) The present invention, as shown in the block diagram in FIG. The refrigerant flow control device of the harmonizer is connected in series to the user-side coil 3 and interposed in the liquid pipe, and the above-mentioned electrically operated refrigerant control valve 4 is connected, and the control for controlling the valve opening of the electrically operated refrigerant control valve 4 is performed. It is composed of the system,
This control system includes a fluid temperature setting means 5 for determining the temperature of a fluid such as air or water, a fluid temperature detection means 6, a first refrigerant temperature detection means 7, a second refrigerant temperature detection means 8, and a valve opening means. It is formed by a temperature calculation means 9, a temperature difference check means 10, a valve opening degree correction means 11, and an output device 12.

As described above, the electrically operated refrigerant control valve 4 is a valve that has an electric device such as a pulse motor as a driving element and adjusts the valve opening according to the amount of electricity.

On the other hand, regarding each element of the control system, first, the fluid temperature setting means 5 is a setting device having a variable resistance such as a potentiometer, and is used to electrically set the reference value T _S of the desired fluid temperature during cooling or heating. It is formed so that it can be set by changing the amount (voltage).

The fluid temperature may be the temperature of air or water flowing into the utilization side coil 3, or the temperature of air or water flowing out.

On the other hand, the fluid temperature detection means 6 is a resistance circuit having a temperature-sensitive resistor such as a thermistor whose resistance value changes with a change in temperature as a detection element. It is arranged at a position where the temperature T _A of the air or blown air can be detected, and is formed so that the temperature _TA of the suction air or blown air can be output as a change in the amount of electricity (voltage).

In the case of water, the temperature of the inlet water pipe or the outlet water pipe to the user-side coil 3 may be detected.

Next, the first refrigerant temperature detection means 7 includes a temperature-sensitive resistor such as a thermistor at a position where it can detect the refrigerant temperature T _O on the refrigerant outflow side of the user side coil 3, and generates an amount of electricity corresponding to the refrigerant temperature TO. (voltage), and is formed so that it can detect the refrigerant temperature T _O in an overheated state during cooling and in a subcooled state during heating after completing heat exchange with the fluid.

The second refrigerant temperature detection means 8 includes a temperature-sensitive resistor such as a thermistor installed on the refrigerant inflow side of the user coil 3 or in the middle of the coil so that the refrigerant temperature can be detected. Therefore, the refrigerant temperature T _R at the time of evaporation or condensation and phase change from liquid to gas or from gas to liquid can be detected.

The valve opening calculation means 9 is composed of a calculation device consisting of a subtractor and a multiplier, etc., and the fluid temperature setting means 5
and the output of the fluid temperature detection means 6 as input signals, calculate the temperature difference between the fluid temperature T _A and the fluid temperature reference value T _S , and set the valve opening to a value proportional to the temperature difference. A can be calculated, and the unit valve opening degree ΔA can be further subtracted from this valve opening degree A by an external command.

Next, the temperature difference checking means 10 is composed of an arithmetic device including a subtractor and a comparator, and receives the output of the first refrigerant temperature detection means 7 and the output of the second refrigerant temperature detection means 8 as input signals, respectively. , the temperature difference between the two types of refrigerant temperatures T _O and T _R , that is, the temperature corresponding to the degree of superheating during cooling and the degree of subcooling during heating, is calculated and compared with a predetermined value △T, and this predetermined value △ When T is larger, an aperture command signal is transmitted.

The valve opening degree correction means 11 receives the output of the temperature difference checking means 10, that is, the throttle command signal, as an input signal, and when this input signal is received, the valve opening degree calculation means 9 is instructed to perform the calculation. A circuit is formed to issue a command to further subtract an opening degree of about 2% from the unit valve opening degree ΔA, for example, the fully open valve opening degree, to the valve opening degree A.

Finally, the output device 12 consists of an output amplifier, and the result calculated by the valve opening calculation means 11 is A-△A.
generates an output corresponding to the A-
The output circuit is formed to be able to maintain the valve opening at ΔA.

(Function) The refrigerant flow rate control device having the above-mentioned means periodically synchronizes the valve opening calculating means 9, the temperature difference checking means 10, and the valve opening correcting means 11,
The refrigerant control valve 4 calculates the valve opening, checks the temperature difference, and corrects the valve opening so that the refrigerant state at the outlet of the user side coil 3 is always maintained close to the wet region of the dry region during cooling. On the other hand, during heating, the valve opening is adjusted so that the state of the refrigerant at the outlet of the user-side coil 3 is always maintained close to the flash area of the liquid seal area.

At that time, the valve opening calculation means 9 naturally determines the valve opening so that the user side coil 3 is maintained at an appropriate degree of superheating during cooling and at an appropriate degree of subcooling during heating. , and when the temperature difference checking means 10 checks the wet state (during cooling) or the flashing state (during heating), the valve opening correction means 1
Since the valve 1 issues a command to reduce the valve opening by the unit valve opening △A, the refrigerant control valve 4 is slightly throttled, returning the wet state or flash state to the appropriate degree of superheating or supercooling. The valve opening degree is automatically adjusted to

(Embodiment 1) FIG. 2 is a refrigeration circuit diagram of a two-chamber cooling air conditioner according to an embodiment of the present invention, and shows an indoor cooling system equipped with a compressor 1 and an outdoor coil 2 serving as a heat source side coil. In contrast to the outer unit, two indoor units are connected in series with an air-type indoor coil 3 serving as a utilization side coil and an electrically actuated refrigerant control valve (hereinafter referred to as an expansion valve) 4 connected to the liquid pipe. 13 and are connected in parallel via a gas pipe 14.

Each indoor unit has three temperature detection sensors (hereinafter referred to as sensors) each consisting of a temperature-sensitive resistor.
The pulse motor 1, which is a driving element of the expansion valve 4, receives signals from T ₁ , T ₂ , T ₃ and the sensors T ₁ to _{T 3} .
The sensor T ₁ is arranged at the air suction part of the indoor coil 3 to detect the temperature T _A of the suction air, and the sensor T ₂ acts as an evaporator. Indoor coil 3
The sensor T ₃ is attached to the outlet pipe at the refrigerant outflow side of the indoor coil 3 to detect the refrigerant temperature T _O after completing heat exchange with the suction air. It is designed to detect the evaporation temperature T _R of the refrigerant.

On the other hand, the controller C controls the fluid temperature (room temperature)
Setting means 5, fluid temperature (room temperature) detection means 6 associated with sensor _T1 , first refrigerant temperature detection means 7 associated with sensor _T2 , second refrigerant temperature detection associated with sensor _T3 . means 8, valve opening calculation means 9,
Temperature difference checking means 10, valve opening correction means 11, and output device 12 that outputs output to pulse motor 15.
Each of these components 5 to 9, 12
The content of is as described above, so the explanation will be omitted.The temperature difference is calculated and compared with a predetermined value, for example, 5℃.If the temperature difference is 5℃ or less, an aperture command signal is issued, and if it is larger than 5℃, the aperture command signal is issued. It is configured to issue an opening command signal, and is inactive during a transient operation period at the time of start-up, and is configured to perform a temperature difference check periodically during steady operation, for example, every few tens of seconds. .

Next, the valve opening correction means 11 is operated in conjunction with the temperature difference checking means 10.
When the throttle command signal is received, the valve opening calculation means 9 calculates the calculated valve opening A and the unit valve opening △.
Issue a command to perform the subtraction A-△A of A, and
When receiving the opening command signal, only when the opening of the expansion valve 4 has been corrected, a command is issued to add the unit valve opening ΔA to the current valve opening.

Next, the mode of controlling the opening degree of the valve 4 by the controller C will be explained below with reference to the flow chart shown in FIG.

The room temperature reference value T _S is set in advance by the room temperature setting means 5, and the controller C starts the controlled operation (a).

During the startup transition period from when the compressor 1 is started until stable cooling operation is performed by the indoor coil 3, the valve opening calculation means 9 uses the valve opening correction means 1.
Since the correction command signal from 1 has not been input (b), calculations are performed to obtain the predetermined valve opening degree (A = K _P T _A - T _S , where K _P is a proportionality constant), and according to this result, By outputting an output from the output device 12 (e), the expansion valve 4 is opened to its valve opening degree A.

Thereafter, when steady operation is reached, an operation command is issued by, for example, a timer (f), and both means 10 and 11 operate synchronously.

First, the temperature difference check means 10 compares the current temperature difference with a predetermined value ΔT, for example, 5°C (g), and if the comparison result is T _O −T _R ≦ΔT, this means that the indoor coil 3 This indicates that the damp operating condition is reached at the exit of the valve, so a throttle command signal is issued.

Thus, from the valve opening correction means 11, △A → △A
+△A _O (where △A _O ; correction value, for example, a signal corresponding to a unit valve opening of 2% opening (ratio to full open) is emitted (H), whereby the valve opening calculating means 9 A calculation is performed to subtract the unit valve opening degree ΔA from the current valve opening degree, and the calculation result is output (d).

Therefore, the output device 12 provides an output to the pulse motor 15 so that the valve opening is obtained by subtracting the unit valve opening ΔA based on the calculation result.
The expansion valve 4 is throttled by 2%.

After that, in response to the timer issuing commands every few tens of seconds, the sequence of operations (g) → (ch) → (d) → (e) is repeated until T _O −T _R > △T. Periodically perform stepwise reduction in steps of 2% until the condition is changed to T _O −T _R ＞△
When an opening command signal is output from the temperature difference checking means 10 due to the temperature being T, the valve opening degree correction means 1
1 detects this while the unit valve opening △A is subtracted even once and the valve opening is corrected.
If T _O −T _R >ΔT, the output device 12 outputs an output (nu) that opens the expansion valve 4 every unit valve opening (2% opening).

In this way, the expansion valve 4 opens at a value corresponding to the valve opening degree A=K _P T _A −T _S ) and returns to the initial state in which the correction value ΔA is not subtracted.

In this way, the refrigerant flow rate of the indoor coil 3 is controlled so that the coil outlet is operated on the side closer to the wet side of the dry area.

(Embodiment 2) Fig. 4 is a refrigeration circuit diagram of a two-chamber type air conditioner for heating and cooling according to an embodiment of the present invention, and the outdoor unit includes a four-way selector valve 16 and an expansion valve 1 exclusively for heating operation.
7 is added to the device shown in the second figure to serve both as air-conditioning and heating.

Note that 18 is the inlet of the expansion valve 17 during cooling;
It is a check valve that can short-circuit the outlet.

This illustrated device has a sensor T ₄ in addition to the sensors T ₁ , T ₂ , and T ₃ in the indoor unit,
This is related to the controller C as an input element, and the sensor T ₁ is arranged at the air intake part of the indoor coil 3 to detect the intake air temperature T _A , and the sensor T ₂ is arranged at the air intake part of the indoor coil 3 to detect the intake air temperature T A. The sensors T ₁ and T ₂ are attached to the ends of the coil tubes, which are the refrigerant outflow side and the refrigerant inflow side during heating, to detect the refrigerant temperature T _O during cooling operation, that is, the degree of superheat. It has the same function as the example shown.

Next, the sensor _T3 is attached to the middle point of the coil and is a dual-purpose sensor for cooling and heating, which can detect the evaporation temperature T _R =T _E during cooling and the condensation temperature T _R =T _C during heating. By performing the cooling/heating switching operation within the controller C, a connection with the circuit is established so that the detection level changes at the same time.

On the other hand, the sensor T ₄ is attached to the coil tube end which is the refrigerant outflow side during heating and the refrigerant inflow side during cooling of the indoor coil 3 to detect the refrigerant temperature T _O during heating operation, that is, the degree of subcooling. ing.

As is clear from the above explanation, during cooling operation, the sensors T ₁ , T ₂ , and T ₃ are connected to the controller C, and the operating mode in that case is exactly the same as the above explanation based on FIG. , during heating operation, sensors T ₁ , T ₃ , and T ₄ are connected to controller C,
Its operating mode is as shown in FIG.

In FIG. 5, the temperature difference check by the temperature difference check means 10 indicates that the temperature difference between T _R (corresponding to the refrigerant temperature T _C at the time of condensation) and T _O (supercooling temperature after heat exchange is completed) is a predetermined value △T. The only difference is to compare whether it is larger or smaller than , and other operating modes are performed in the same manner as during cooling, and as a result, the refrigerant outflow side end of the indoor coil 3 is close to the flash area of the liquid seal area. Valve opening control is performed mainly on the throttle side of the expansion valve 4 so that it is always maintained stably on the throttle side.

The embodiments described above show both cases for cooling only and cases for both heating and cooling, but it is natural that examples for use only for heating can also be considered, and these are also naturally included as examples of the present invention. It is something that

In addition, in the above embodiment, the valve opening degree of the expansion valve (refrigerant control valve) is controlled according to the difference between the intake air temperature of the indoor coil 3 as the user side coil and the reference value of the room temperature. However, instead of this, the valve opening degree of the refrigerant control valve 4 may be controlled according to the difference between the temperature of the air blown from the utilization side coil and the reference value of the blown air.

In addition to air, the fluid that exchanges heat in the user-side coil may be water. Therefore, it can be applied not only to chillers dedicated to cooling, but also to heat pump type chillers.

Furthermore, in the above embodiments, the multi-room air conditioner in which a plurality of indoor units are connected to one outdoor unit was explained, especially when a plurality of indoor units are connected to a single outdoor unit. In an air conditioner made of a This is because it is particularly effective.

However, the present invention can also be applied to a separate type air conditioner in which one indoor unit is connected to one outdoor unit, and can also be applied to an integrated type air conditioner instead of a separate type.

(Effects of the Invention) The present invention adjusts the state of the refrigerant at the refrigerant outflow side of the utilization side coil 3 to an appropriate minimum degree of superheat that does not cause liquid return to the compressor 1 during cooling. In addition, during heating, by controlling the valve opening degree of the electrically operated refrigerant control valve 4, the user side Since this method directly controls the flow rate of the refrigerant flowing into the coil 3, it is possible to utilize almost 100% of the heat exchange capacity of the coil 3 on the user side, and it is also safe by suppressing the occurrence of dampness and flashing. This results in high efficiency and efficient operation.

Furthermore, there is no need to provide a capacity control mechanism for the compressor 1 or a hot gas bypass device to eliminate moisture intake, which simplifies the circuit configuration, reduces equipment costs, and allows for efficient operation. By doing so, it is possible to improve energy conservation.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram clearly showing the configuration of the present invention, FIGS. 2 and 3 are refrigeration circuit diagrams and flow diagrams showing operating modes according to an example of the present invention, and FIGS. 4 and 5
The figure is a refrigeration circuit diagram and a flow diagram showing an operation mode according to an example of the present invention. 1... Compressor, 2... Heat source side coil, 3... User side coil, 4... Electrically operated refrigerant control valve, 5...
Fluid temperature setting means, 6...Fluid temperature detection means, 7
...First refrigerant temperature detection means, 8...Second refrigerant temperature detection means, 9...Valve opening calculation means, 10...Temperature difference checking means, 11...Valve opening correction means, 12
...Output device.

Claims (1)

[Claims] 1 Compressor 1, heat source side coil 2, user side coil 3
In an air conditioner formed by a refrigeration circuit equipped with a refrigeration circuit, the valve opening degree is adjusted according to the amount of electricity, and an electric actuator connected in series to the user side coil 3 and interposed in the liquid pipe A refrigerant control valve 4, a fluid temperature setting means 5 for setting a reference value T _S of the temperature of the fluid with which heat exchange is performed by the use side coil 3, and a fluid temperature detecting means 6 for detecting the temperature T _A of the fluid. , refrigerant temperature T _O at the refrigerant outflow side of the user side coil 3,
That is, the first refrigerant temperature detection means 7 detects the temperature of the refrigerant after completing the heat exchange with the fluid, and the refrigerant temperature detecting means 7 detects the temperature of the refrigerant after completing the heat exchange with the fluid. refrigerant temperature
a second refrigerant temperature detection means 8 for detecting T _R ; and a temperature of the fluid detected by the fluid temperature detection means 6.
Valve opening calculating means 9 for determining the temperature difference between T _A and the reference value T _S set by the fluid temperature setting means 5, and calculating a valve opening A having a value proportional to the temperature difference; The temperature difference between the refrigerant temperature T _O detected by the refrigerant temperature detection means 7 and the refrigerant temperature T _R detected by the second refrigerant temperature detection means 8 is determined, and this is compared with a predetermined value ΔT. Temperature difference checking means 10 transmits an aperture command signal when .
In response to the aperture command signal from the temperature difference checking means 10, the valve opening calculation means 9 further subtracts a unit valve opening ΔA from the calculated valve opening A.
and an output device 12 that controls the valve opening of the electrically operated refrigerant control valve 4 based on the calculation result of the valve opening calculation means 9. Refrigerant flow control device for conditioner. 2 The user side coil 3 acts as an evaporator, and the first
The refrigerant temperature detection means 7 detects the temperature of the low-pressure refrigerant gas at the refrigerant outflow side of the utilization side coil 3, and
The refrigerant temperature detecting means 8 detects the temperature of the low-pressure refrigerant at the refrigerant inlet side or intermediate portion of the user-side coil 3, and the temperature difference checking means 10 detects the degree of superheating of the refrigerant in the user-side coil 3. A refrigerant flow rate control device for an air conditioner according to claim 1, wherein the refrigerant flow rate control device is operated. 3 The user side coil 3 acts as a condenser, and the first
The refrigerant temperature detection means 7 detects the temperature of the high-pressure refrigerant liquid at the refrigerant outflow side of the usage-side coil 3, and the second refrigerant temperature detection means 8 detects the temperature of the high-pressure refrigerant at the refrigerant distribution intermediate part of the usage-side coil 3. The refrigerant flow rate control device for an air conditioner according to claim 1, wherein heating operation is performed by the temperature difference checking means 10 detecting the degree of subcooling of the refrigerant in the utilization side coil 3.