JPS61114067A - Refrigerant flow controller - 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 [Field of Application of the Invention] The present invention relates to a refrigerant flow rate control device, and particularly to a refrigerant flow rate control device suitable for starting a refrigeration cycle of a refrigeration air conditioner or the like.

[Background of the invention]

As a conventional refrigerant flow rate control device in a refrigeration cycle, there is one described in Japanese Patent Publication No. 58-47628.

That is, in a refrigeration cycle in which a compressor, a condenser, an expansion valve whose opening degree can be adjusted by an electric signal, and an evaporator are connected by refrigerant piping, a first temperature sensor provided at the inlet of the evaporator and the evaporator A second temperature sensor installed at the outlet section is used to detect the degree of superheating of the refrigerant at the outlet of the evaporator, and an electric signal is output to control the opening degree of the expansion valve to keep this degree of superheat constant. It controlled the refrigerant flow rate.

Here, the degree of superheating of the refrigerant refers to the difference between the temperature of the gas that has been superheated to a saturation temperature or higher corresponding to the refrigerant pressure at a certain point, and the saturation temperature.

The refrigerant flow rate control device described in Japanese Patent Publication No. 58-47628 utilizes the fact that the temperature of the refrigerant at the evaporator inlet is approximately equal to the saturation temperature corresponding to the refrigerant pressure at the evaporator outlet. The degree of superheat at the outlet of the container is detected.

However, for example, when starting up a refrigeration cycle such as an air conditioner, the pressure of the refrigerant in the refrigeration cycle is balanced, and the temperature of the refrigerant at the evaporator inlet and outlet are almost the same, so If the degree of superheating of the refrigerant is determined from the temperature difference at the outlet, it will be approximately zero.

At this time, the electric signal that controls the valve opening of the expansion valve becomes a negative value proportional to (evaporator outlet superheat degree - superheat degree set value) = (〇 - superheat degree set value), and the expansion valve opens. Controlled in the closing direction.

Therefore, in refrigeration cycles such as those used in car air conditioners, in which the W expansion valve is closed to prevent liquid refrigerant from flowing into the compressor when the air conditioner is stopped, When the air conditioner is started, the expansion valve is controlled in the closing direction, so it remains closed and no refrigerant flows, so the pressure and temperature inside the evaporator decrease.

Since there is no temperature difference between the refrigerant at the evaporator inlet and outlet, the degree of superheat determined as the difference between the temperature at the evaporator outlet and the evaporator inlet is always zero, and the expansion valve continues to close. was there.

Therefore, in the invention described in Japanese Patent Publication No. 58-40628, the control circuit outputs a signal to fully open the expansion valve after stopping the refrigeration cycle, and also restarts the compressor for a certain period of time. However, in this invention, the idea of the present invention as described below was not taken into consideration.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned problems, and when the refrigerant flow rate is controlled by detecting the degree of superheat of the evaporator refrigerant using only a temperature sensor, the expansion valve is The expansion valve can be controlled in the direction of opening, preventing the expansion valve from remaining closed.

The objective is to provide a refrigerant flow rate control device that enables control of refrigerant flow rate according to heat load.

[Summary of the invention]

The configuration of the refrigerant flow rate control device according to the present invention is such that a refrigeration cycle is configured by connecting a compressor, a condenser, an expansion valve whose opening degree can be adjusted by an electric signal, and an evaporator through refrigerant piping, and A first temperature sensor provided at an inlet or an intermediate portion, a second temperature sensor provided at an outlet of the evaporator, and a refrigerant connecting the inlet of the compressor or the evaporator and the compressor. A third temperature sensor provided in the vicinity of the compressor of the piping, a difference in temperature signal between the first temperature sensor and the second temperature sensor, and a difference between the temperature signals of the first temperature sensor and the third temperature sensor. and a control circuit that outputs an electric signal to the expansion valve so as to maintain the difference between each temperature signal with the temperature sensor at a set value, and at the time of starting the refrigeration cycle, the first temperature sensor and the An electric signal is output to the expansion valve in order to maintain the difference between the respective temperature signals with the third temperature sensor at a set value, and after a certain period of time has elapsed, the temperature signals between the first temperature sensor and the third temperature sensor are outputted. An arithmetic and control device is provided in which a control procedure can be set in advance so as to output an electric signal to the expansion valve in order to maintain the difference between each temperature signal from the temperature sensor at a set value.

Additionally, the idea behind developing the present invention is as follows.

When the refrigeration cycle of an air conditioner, etc. is stopped, the temperature of the refrigerant at the evaporator inlet is lowered by the temperature at the compressor inlet or the area near the compressor of the refrigerant piping connecting the evaporator and compressor (hereinafter collectively referred to as the compressor inlet). ) is higher, and the electrical signal that controls the valve opening of the expansion valve when starting the air conditioner is set to (compressor inlet refrigerant temperature - evaporator inlet refrigerant temperature - The idea was to control the refrigerant flow rate at startup as a value proportional to the set value of the degree of superheat.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

First, FIG. 1 is a block diagram of a refrigerant flow rate control device according to an embodiment of the present invention.

In FIG. 1, 1 is a compressor, 2 is a condenser, and 3 is 1!
! An expansion valve whose opening degree can be adjusted by a gas signal, and an evaporator 4 are connected by refrigerant piping to form a refrigeration cycle.

The refrigerant compressed by the compressor 1 to become a high-temperature, high-pressure superheated gas is cooled by the condenser 2, condenses, becomes a high-pressure liquid refrigerant, flows down, is controlled in flow rate by the expansion valve 3, and expands adiabatically. The refrigerant becomes a low-pressure refrigerant and evaporates while taking heat from the outside in the evaporator 4, and the evaporated refrigerant gas is sucked into the compressor 1 again.

5 is a first temperature sensor provided at the inlet or intermediate portion of the evaporator 4 (the inlet in FIG. 1); 6 is a second temperature sensor provided at the outlet of the evaporator 4; 7; A third temperature sensor 9 provided at the inlet of the compressor 1 is a superheat degree calculation circuit, and this superheat degree calculation circuit 9 calculates the respective temperatures of the first temperature sensor 5 and the second temperature sensor 6. The degree of superheat of the refrigerant at the outlet of the evaporator 4 detected as a difference in signals, and the refrigerant at the outlet of the compressor 1 detected as a difference between the temperature signals of the first temperature sensor 5 and the third temperature sensor 7. This is to find the degree of superheat.

10 is a superheat degree setting circuit; 11 is a differential amplifier that calculates the deviation between the superheat degree SH of the refrigerant detected by each temperature sensor and a predetermined superheat degree setting value S.H''; A control calculation circuit 13 determines the valve opening degree of the expansion valve 3 according to the calculation result of the control calculation circuit 12.
A valve drive circuit that outputs an electric signal to the valve drive circuit constitutes a refrigerant flow rate calculation and control device 8 related to the calculation and control device shown by the dashed line.

In the normal operating state of the refrigeration cycle, in order to evaporate just the right amount of refrigerant in the evaporator 4 according to the external heat load, the difference between the temperature signals between the first temperature sensor 5 and the second temperature sensor 6 is determined. The superheat degree SH of the refrigerant at the outlet of the evaporator 4 is determined by the superheat degree calculation circuit 9, and the deviation between this value and a set value SH'' stored in advance in the superheat degree setting circuit 10 is determined by the differential amplifier 11. The control calculation circuit 12 determines the opening degree of the expansion valve 3 according to this deviation, and the valve drive circuit 13
An electric signal is sent to the actuator (not shown) of the expansion valve 3 so that the deviation between SH and SH'' becomes zero.
The valve opening is adjusted to control the refrigerant flow rate.

This is the same as the conventional refrigerant flow rate control device described in Japanese Patent Publication No. 58-47628.

In this embodiment, as already mentioned, the third temperature sensor 7 is also provided at the inlet of the compressor 1, and when the air conditioner etc. is started, the third temperature sensor 7 and the first temperature The refrigerant superheat degree is calculated using the sensor 5.

The operation of the refrigerant flow rate calculation and control device 8 configured as described above will be explained with reference to FIGS. 1 and 2.

FIG. 2 is a flowchart illustrating the operation of the refrigerant flow rate control device shown in FIG. 1.

After starting the air conditioner, etc., measure the time after starting with a timer (not shown), and wait until a certain period of time (8 seconds) has elapsed.
The degree of superheating is calculated using the temperature signals T, , T, of the third temperature sensor 7 provided at the inlet of the compressor 1 and the first temperature sensor 5 provided at the inlet of the evaporator 4. A circuit 9 determines the degree of superheating SH as 5H=T, -T5. This degree of superheating SH
The difference e=sH-8H'' between the set value SH'' set in the superheat degree setting circuit 10 is obtained by the differential amplifier 11, and this signal is processed using the control calculation circuit 12 and the valve drive circuit 13 to calculate the deviation. The electric signal V=f (e) according to e is sent to the expansion valve 3
send to

After a certain period of time S seconds has elapsed, the second
The degree of superheating SH is determined as 5H=T, -T by using the temperature signals T6°T of the temperature sensor 6 and the first temperature sensor 5 provided at the inlet of the evaporator 4, respectively.

After that, the same signal processing as described above is performed.

When refrigerant flow rate control is performed in this way, 1. For example, the compressor 1 of a car air conditioner installed in the engine room of a car.
Since the temperature T7 at the inlet of the evaporator 4 is sufficiently higher than the temperature Ts at the inlet of the evaporator 4 even before the air conditioner is started, the deviation e becomes positive and the expansion valve 3 opens.

After the expansion valve 3 opens and after a certain period of time S seconds, the refrigerant reaches a degree of superheat at the outlet of the evaporator 4, and then the evaporator 4
Since the refrigerant flow rate is controlled using the refrigerant superheat degree signal at the outlet of the refrigerant, the refrigerant flow rate can be controlled without the expansion valve 3 remaining closed when the air conditioner is started.

Next, another embodiment of the present invention will be described with reference to FIGS. 3 and 4.

FIG. 3 is a block diagram of a refrigerant flow rate control device according to another embodiment of the present invention, and FIG. 4 is a flowchart illustrating the operation of the refrigerant flow rate control device of FIG. 3.

In FIGS. 3 and 4, the same reference numerals or symbols as those in FIGS. 1 and 2 are the same parts as in the above-mentioned embodiment, so the explanation thereof will be omitted.

The embodiment shown in FIG. 3 is similar to the filtration heat calculation circuit 9 in the embodiment shown in FIG. Superheat degree setting circuit 10. Differential amplifier 11. The control calculation circuit 12 is replaced with a microcomputer. 8A indicated by a dashed line is a refrigerant flow rate calculation and control device centered on a microcomputer 6. The microcomputer is a CPU 15. Memory unit 16. It is composed of an AD converter 14.

The temperature signal of the evaporator 4 artificial refrigerant detected by the first temperature sensor 5, the temperature signal of the evaporator 4 outlet refrigerant detected by the second temperature sensor 6, and the compression detected by the third temperature sensor 7. The temperature signals of the machine 1 artificial refrigerant are each converted into digital signals by the AD converter 14, and then processed by the CPU 15.

Based on these signals, the CPU 15 controls the memory unit 16.
The degree of superheat is calculated according to the procedure stored in the controller, the deviation from the predetermined set value of the degree of superheat is determined, control calculations are performed, the valve opening degree is determined, and a signal is sent to the valve drive circuit 13A.

With this configuration, the arithmetic operations shown in FIG. 2 can be processed on a program without configuring an arithmetic circuit, so there is no need to provide a separate timer.

FIG. 4 shows the flow of processing when no timer is used.

Microcomputers perform measurement and calculation processing in series, and each processing requires a finite amount of time. Therefore, as shown in FIG. 4, the number of times the routine of superheat degree detection, calculation, deviation calculation, control calculation, and valve control has been performed after startup is counted. In other words, it can be used in place of a timer by determining whether the loop is 8 times or not.

In the above embodiment, an example of refrigerant flow rate control at the time of starting a car air conditioner was explained, but the present invention is not limited to car air conditioners, but can be applied to refrigerant flow rate control in the refrigeration cycle of product equipment that is expected to have the same effect. It is a general-purpose device within the range of control devices.

〔Effect of the invention〕

As described above, according to the present invention, when controlling the refrigerant flow rate by detecting the degree of superheating of the evaporator refrigerant using only the temperature sensor, the expansion valve can be controlled in the direction of opening when the refrigeration cycle is started. , preventing the expansion valve from remaining closed,
A refrigerant flow rate control device that enables control of refrigerant flow rate according to heat load can be provided.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a refrigerant flow rate control device according to an embodiment of the present invention, FIG. 2 is a flowchart explaining the operation of the refrigerant flow rate control device of FIG. 1, and FIG. FIG. 4 is a flowchart illustrating the operation of the refrigerant flow control device of FIG. 3, which is a block diagram of the refrigerant flow control device according to the embodiment.・1... Compressor, 2... Condenser, 3... Expansion valve, 4... Evaporator, 5... First temperature sensor, 6
... second temperature sensor, 7... third temperature sensor,
8, 8A... Refrigerant flow rate calculation control device, 9... Superheat degree calculation circuit, 10... Superheat degree setting circuit, 11... Differential amplifier, 12... Control calculation circuit, 13, 13A.・・・
Valve drive circuit, 14... AD converter, 15... CPU
, 16... memory unit. Rod I (2) No. 31!11

Claims (1)

[Claims] 1. A refrigeration cycle is constructed by connecting a compressor, a condenser, an expansion valve whose opening degree can be adjusted by an electric signal, and an evaporator through refrigerant piping, and a first a second temperature sensor provided at the outlet of the evaporator, and a second temperature sensor provided at the inlet of the compressor or near the compressor of a refrigerant pipe connecting the evaporator and the compressor. The difference between the temperature signals of the third temperature sensor, the first temperature sensor, and the second temperature sensor, and the difference between the temperature signals of the first temperature sensor and the third temperature sensor. and a control circuit that outputs an electric signal to the expansion valve so as to maintain the difference at a set value, and at the time of startup of the refrigeration cycle, the temperature of each of the first temperature sensor and the third temperature sensor An electric signal is output to the expansion valve in order to maintain the difference between the signals at a set value, and after a certain period of time has elapsed, the difference between the temperature signals of the first temperature sensor and the third temperature sensor is determined. 1. A refrigerant flow rate control device comprising an arithmetic and control device capable of setting a control procedure in advance so as to output an electric signal to the expansion valve in order to maintain the expansion valve at a set value.