JPS6325270B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a defrosting device for a heating and cooling system, and aims to simplify the refrigeration cycle and improve defrosting efficiency.

Conventionally, there are various types of defrosting devices for heating and cooling systems. FIG. 1 shows a conventional embodiment.

Figure 1 shows a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, a check valve 4, a heating capillary tube 5, a cooling/heating capillary tube 6, an indoor heat exchanger 7, a four-way valve 2, and an accumulator. 8. During cooling operation, refrigerant flows sequentially as shown by solid line arrows in the figure and returns to the compressor 1, and during heating operation, refrigerant flows as shown by broken line arrows in the figure. Furthermore, the defrosting control device has a frost detection device that detects the state of frost formation during heating operation, and in response to the signal from the frost detection device, cooling operation is performed and the electromagnetic switch 9 shown in the figure is opened to increase the amount of refrigerant. As shown by the dashed-dotted line arrow in the figure, a refrigeration cycle is constructed in which the defrosting capillary reach tube 10 is bypassed to the accumulator 8, and a device for stopping indoor and outdoor blowers is also provided. Perform frost operation.

With such a configuration, an electromagnetic switch 9, a capillary reach tube 10, a branch pipe, etc. are required for defrosting, which increases costs, increases installation space, and deteriorates quality due to an increase in the number of parts. This had the disadvantage that management, services, etc. were complicated.

The present invention includes a compressor, a heating/cooling switching valve, an outdoor heat exchanger,
A refrigeration circuit is constructed by connecting a throttling device and an indoor heat exchanger in a ring, and a forward and reverse flow type thermoelectric expansion valve is used as the throttling device, and a detection device for detecting frost formation, and the outdoor heat exchanger and A detection device that detects the refrigerant state such as the refrigerant temperature of each of the indoor heat exchangers, and a cooling operation based on the signal from the frost detection device, and a detection value of the refrigerant state detection device of the outdoor heat exchanger. Correspondingly, calculate the refrigerant state of the indoor heat exchanger that maximizes the output of the compressor.
A state setting section to be set compares a set value of this state setting section with a detected value of a refrigerant state detection device of the indoor heat exchanger, and controls the opening degree of the thermoelectric expansion valve so that both values match. The above-mentioned drawbacks of the conventional art are improved by providing a control device having an opening degree control section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIGS. 2 to 4 of the accompanying drawings showing one embodiment thereof.

In Fig. 2, 12 is a compressor, 13 is a four-way valve, 14 is an outdoor heat exchanger, 15 is a forward-reverse flow type thermoelectric expansion valve, 16 is an indoor heat exchanger, and 17 is an accumulator, which are arranged in a ring. A refrigeration cycle is constructed by connecting the 18 is an outdoor blower, 19 is an indoor blower, 20 is a thermistor provided in the outdoor heat exchanger 14, 21 is a thermistor provided in the indoor heat exchanger 16, 22 is a suction part of the compressor 12, and 23 is the compressor 12 is a thermistor provided in the suction part 22, 24 is the thermistor 20, 2
This is a control device that controls the opening degree of the thermoelectric expansion valve 15 based on electrical resistance values of 1 and 22, and switches between cooling operation, heating operation, and defrosting operation.

Next, the control circuit will be explained with reference to FIG.
In the same figure, 25 is a microcomputer,
Compressor 12, indoor/outdoor blower 19, 18, four-way valve 1
In addition to the operation control of 3, thermistors 20, 21, 2
3 controls the voltage applied to the thermoelectric expansion valve 15. 26 is an operation switch for the compressor 12, 27 is an electromagnetic switch for the compressor 12, 28 is a speed change switch for the indoor blower 19, 29 is an electromagnetic switch for the indoor blower, 30 is a heating/cooling switch, 31
3 is an electromagnetic switch for a four-way valve, 32 is an electromagnetic switch for an outdoor blower, and 33 is a V-F converter, which converts the voltage from the thermistors 20, 21, and 23 into a frequency and sends it to the microcomputer 25. 34, 35,
36 is a fixed resistor for each thermistor 20, 21, 23, and 37 is a device that converts a signal from the microcomputer 25 into a voltage and applies it to the thermoelectric expansion valve 15.

Next, the operation of this control circuit will be briefly explained. During the cooling operation, the operation switch 26 of the compressor 12 is turned on, and the electromagnetic switch 27 is turned on, so that the compressor 12 is turned on.
is operated, and the speed change switch 2 of the indoor fan 19 is turned on.
8 is turned on, the one corresponding to the speed change switch 28 in the electromagnetic switch 29 is turned on, and the indoor blower 19 is operated, and the cooling/heating switch 30 for the four-way valve is not turned on, and the electromagnetic switch for the four-way valve is turned on. 31 doesn't fit. As a result, the four-way valve 13 is on the cooling side, and the electromagnetic switch 32 for the outdoor blower is turned on. The microcomputer 25 also receives the signals from the thermistors 20, 21, and 23 that have come in via the V-F converter 33, calculates the temperature of each thermistor, and further calculates the temperature difference between the thermistor 21 and thermistor 23. The voltage applied to the thermoelectric expansion valve 15 is controlled by comparing it with a preset value and changing the signal sent to the voltage conversion device 37. In other words, if the value obtained by subtracting the temperature of the thermistor 21 from the temperature of the thermistor 23 is smaller than the set value, the refrigerant flow rate is too large, so a signal is sent to reduce the valve opening of the thermoelectric expansion valve 15. , conversely, thermistors 23 and 21
If the temperature difference is large, a signal is issued to increase the valve opening of the thermoelectric expansion valve 15.

Also, during heating operation, the cooling/heating switch 30 for the four-way valve is turned on, so the electromagnetic switch 31 for the four-way valve is turned on.
is turned on, and the four-way valve 13 is switched to the warm return side. The thermistor 21 replaces the thermistor 20 during cooling operation, and other operations are the same as during cooling. Next, the time of defrosting will be explained. When the temperature of the thermistor 20 falls below the value set for starting defrosting, the microcomputer 25 issues a signal to start defrosting operation. As a result, the electromagnetic switch 29 of the indoor blower is not turned on at all, and the electromagnetic switch 32 of the outdoor blower is also not turned on. Furthermore, since the electromagnetic switch 31 of the four-way valve 13 is not turned on, the four-way valve 13 is switched to the cooling side and performs cooling operation. In addition, the microcomputer 25 calculates the output of the compressor 12 from the temperatures of the thermistor 20 and thermistor 21, and uses a voltage converter to control the opening degree of the thermoelectric expansion valve 15 so that the output of the compressor 12 is maximized. 37. As is well known, for any given condensing temperature, the output of a compressor decreases if the vapor temperature is too low or too high, and there is a maximum evaporation temperature (and therefore compression ratio). The microcomputer 25 is provided with a circuit for calculating an evaporation temperature at which the output of the compressor 12 becomes approximately maximum for each condensation temperature during defrosting. The control method is to calculate and set the evaporation temperature using the microcomputer 25 from the temperature of the thermistor 20 (condensation temperature), and control the opening degree of the thermoelectric expansion valve 15 so that the temperature of the thermistor 21 matches this set value. Defrosting operation is performed and thermistor 2
When the temperature of 0 becomes equal to or higher than the temperature set for ending defrosting, the microcomputer 25 issues a signal to end defrosting, that is, a signal to return to heating operation, and normal heating operation is performed.

Next, we will discuss the structure of the thermoelectric expansion valve 15 in the fourth section.
The explanation will be explained with reference to the figure. Thermoelectric expansion valve 15 consists of a valve part 40 and a valve drive part 41. Valve part 40
consists of a valve frame 42 and a valve body 43. The valve frame 42 is provided with a valve seat 44 and has an inflow port 45 and an outflow port 46 through which fluid flows in and out.
Refrigerant pipes 47 and 48 are connected to the refrigerant pipes 5 and 46, respectively. The valve body 43 consists of two connected upper and lower members 49, 50.
Passages 51 and 52 are formed therein to communicate the outflow port 46 side with the inside of the valve driving portion 41. Between both passages 51 and 52, refrigerant flows from passage 52 to passage 51.
A check valve 53 is provided to prevent the water from flowing towards the water. Note that the valve body 43 is provided in a hole 54 formed in the valve frame 42 so as to be vertically slidable. On the other hand, the valve driving portion 41 forms a sealed space 57 with the upper casing 55, the lower casing 56, and the valve frame 42. Two bimetals 58 and 59 are housed in this space 57, and both bimetals 58 and 59 have spacers 60 and 60 at both ends.
They are arranged in parallel via 61. Then, holes 62 and 63 are bored in the center of both bimetals 58 and 59,
A support pin 64 fixed to the center of the inner surface of the upper casing 55 is inserted into the hole 62 of the upper bimetal 58 from above, and a pin portion 65 formed at the upper end of the valve body 43 is inserted into the hole 63 of the lower bimetal 59 from below. By inserting, both bimetals 58 and 59 are supported in the space 57. Note that the valve body 43 is always urged upward by a spring 67 via the seat 66. Reference numeral 68 denotes an electric heater that forcibly heats the upper bimetal 58, and is wound around the upper bimetal 58. 69 and 70 are terminals connected to both ends of the electric heater 68, and are connected to the upper casing 55.
It is installed through the. Bimetal 5 on top of this
8 is forcibly heated by an electric heater 68, thereby deforming so that both ends thereof move upward (in the direction of arrow A in the figure).

Therefore, when the electric heater 68 is energized, the upper bimetal 58 is deformed, and the spring 67 pushes up the valve body 43 to open the space between the valve seat 44 and the lower end of the valve body 43. In other words, the valve is opened. The degree of opening of the valve in this case is adjusted by the amount of power, that is, the voltage, applied to the electric heater 68. That is, when a large amount of electric power is passed through the upper bimetal 58, the upper bimetal 58 deforms greatly, and the opening degree of the valve increases. Conversely, when the electric power to the electric heater 68 is small, the amount of deformation of the upper bimetal 58 is small and the opening degree of the valve is small. Note that the lower bimetal 59 deforms under the influence of the temperature of the refrigerant flowing into the space 57 from the sliding surface between the hole 54 and the valve body 43 and the ambient air temperature.
This is a bimetal for load condition compensation. Further, this thermoelectric expansion valve 15 is a forward and reverse flow type expansion valve,
The refrigerant flows from the inflow boat 45 and flows through the constriction formed between the valve body 43 and the valve seat 44 to the outflow port 46, and vice versa. It is also possible to flow in from the inflow port 46 and out through the inflow port 45 through a constriction formed between the valve body 43 and the valve seat portion 44 . In this case, due to the shape of the valve, the flow resistance of the refrigerant is slightly smaller when the refrigerant flows from the inflow port 45 to the outflow port 46, as long as the degree of restriction is the same, compared to when the refrigerant flows in the opposite direction. Note that when the pressure on the inflow port 45 side becomes high and the pressure on the outflow port 46 side becomes low, a part of the refrigerant will
The refrigerant flows into the space 57 from the sliding surface between the valve body 43 and the hole 54, and the refrigerant flows through the passages 51, 52.
It flows to the outflow port 46 through the check valve 53 and does not accumulate in the space 57. Conversely, when the pressure on the outflow port 46 side becomes higher than that on the inflow port 45 side, the check valve 53 closes and almost no refrigerant flows into the space 57.

Next, the operation of this embodiment will be explained. First, cooling operation will be explained.

The refrigerant exiting the compressor 12 passes through a four-way valve 13 to an outdoor heat exchanger 14, a forward and reverse flow type thermoelectric expansion valve 15,
The air flows through the indoor heat exchanger 16 and the four-way valve 13 in sequence as shown by the solid line arrow in FIG. 2, and returns to the compressor 12 via the accumulator 17. Further, the thermoelectric expansion valve 15 is controlled by the control device 24 so that the temperature difference between the thermistor 23 and the thermistor 21 is constant (that is, the degree of superheat of the refrigerant in the suction section 22 is constant).

In other words, the refrigerant flow rate is too large and the thermistor 23
If the temperature difference between the thermoelectric expansion valve 15 and the thermistor 21 is smaller than the set value, control is performed to reduce the refrigerant flow rate by reducing the voltage applied to the thermoelectric expansion valve 15 and reducing the valve opening. If the temperature difference is too high, the temperature difference between the thermistors 23 and 21 is controlled to a set value by increasing the valve opening and thereby increasing the refrigerant flow rate.

On the other hand, during heating operation, the refrigerant leaving the compressor 12 passes through the four-way valve 13 to the indoor heat exchanger 16, the forward and reverse flow type thermoelectric expansion valve 15, the outdoor heat exchanger 14, and the four-way valve 13.
2, and returns to the compressor 12 via the accumulator 17 as indicated by the broken line arrows in FIG. Furthermore, the thermoelectric expansion valve 15 includes a thermistor 23 and a thermistor 20.
It is controlled in the same way as during cooling operation so that the temperature difference between the two is constant.

Next, the defrosting operation will be explained. During heating operation, when the amount of heat absorbed by the outdoor heat exchanger 14 decreases due to a drop in the outdoor temperature, etc., the evaporation pressure decreases and the thermistor 2
The temperature at zero also decreases. When the amount of heat absorbed becomes below a certain value, frost begins to form on the outdoor heat exchanger 14, the temperature of the thermistor 20 becomes below the defrosting start setting value, and the control device 24 issues a signal to start defrosting. This signal stops the indoor and outdoor blowers 19 and 18, and the four-way valve 1
3 is switched to the cooling side. In other words, a defrosting operation is performed, which is a refrigeration cycle during cooling when the blower is stopped.

When defrosting operation is started, thermoelectric expansion valve 15 is controlled by thermistors 20 and 21. From the thermistor 20, the microcomputer 25 calculates and sets the evaporation temperature, controls the valve opening of the thermoelectric expansion valve 15 so that the temperature of the thermistor 21 becomes the set value, and when defrosting, the outdoor thermal condensation temperature is controlled. The output of the compressor 12, which is the main heat source for the amount of heat supplied to the converter 14, is controlled to be maximized.

That is, when the temperature of the thermistor 21 is higher than the set value, the compression ratio is increased by reducing the voltage applied to the thermoelectric expansion valve 15, reducing the refrigerant flow rate, and reducing the evaporation pressure. When the temperature is lower than the set value, the voltage applied to the thermoelectric expansion valve 15 is increased to reduce the compression ratio, thereby maintaining the compression ratio constant and always maximizing the output of the compressor 12. Therefore, the defrosting time can be shortened.

When the frost or ice melts and the temperature of the thermistor 20 becomes higher than the defrost end setting value, the control device 24
will issue a signal to end defrosting and normal heating operation will resume.

Furthermore, as another embodiment, the same effect can be obtained by using a thermoelectric expansion valve of an energized closed type with forward and reverse flow, that is, a thermoelectric expansion valve whose valve opening decreases as the applied voltage increases.

Furthermore, instead of controlling the opening degree of the thermoelectric expansion valve 15 so that the output of the compressor 12 is maximized during defrosting operation, since the condensing pressure is almost constant during defrosting, the evaporation pressure is kept constant. A similar effect can also be obtained by controlling the opening degree of the thermoelectric expansion valve 15 to maintain the same value.

As is clear from the above description, the defrosting control device for the air conditioning system according to the present invention has a refrigeration circuit in which an outdoor heat exchanger, a throttling device, and an indoor heat exchanger are connected to a compressor in an annular manner via a cooling/heating switching valve. and uses a forward and reverse flow type thermoelectric expansion valve as a throttling device, and further detects refrigerant conditions such as refrigerant temperature of each of the outdoor heat exchanger and the indoor heat exchanger when frost formation is detected. a detection device; and the indoor heat exchanger performs cooling operation based on a signal from the frost detection device, and maximizes the output of the compressor in response to a detected value of the refrigerant state detection device of the outdoor heat exchanger. A state setting unit that calculates and sets the refrigerant state of the thermoelectric converter compares the set value of this state setting unit with the detected value of the refrigerant state detection device of the indoor heat exchanger, and adjusts the thermoelectric type so that the two values match. By providing a control device with an opening control unit that controls the opening of the expansion valve, costs can be reduced by eliminating the need for a bypass circuit with an electromagnetic switch, etc., as in the past for defrosting operation. At the same time, it has great advantages, such as reducing the installation space and making quality control, maintenance inspection, etc. easier.

[Brief explanation of the drawing]

Fig. 1 is a schematic refrigeration cycle configuration diagram showing a conventional example, Fig. 2 is a schematic refrigeration cycle configuration diagram of an air conditioning system equipped with a defrosting control device according to an embodiment of the present invention, and Fig. 3 is a schematic refrigeration cycle configuration diagram of the same defrosting control device. FIG. 4 is a schematic cross-sectional view of a forward and reverse flow type thermoelectric expansion valve in the defrosting control device. 12...Compressor, 13...Four-way valve, 14...Outdoor heat exchanger, 15...Forward and reverse flow type thermoelectric expansion valve,
16... Indoor heat exchanger, 20, 21, 23... Thermistor, 24... Control device for thermoelectric expansion valve.

Claims (1)

[Claims] 1. A refrigeration circuit is constructed by connecting a compressor, a cooling/heating switching valve, an outdoor heat exchanger, a throttling device, and an indoor heat exchanger in a ring, and a forward-reverse flow type thermoelectric expansion valve is used as the throttling device. a detection device for detecting refrigerant conditions such as the refrigerant temperature of each of the outdoor heat exchanger and the indoor heat exchanger; a state setting unit that calculates and sets a refrigerant state of the indoor heat exchanger in which the output of the compressor is maximized in accordance with a detection value of a refrigerant state detection device of the outdoor heat exchanger; A control device is provided that has an opening degree control unit that compares a set value with a detected value of a refrigerant state detection device of the indoor heat exchanger and controls the opening degree of the thermoelectric expansion valve so that both values match. Defrost control device for heating and cooling equipment.