JPH0563699B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heat pump device in which an electric refrigerant flow control valve that controls the refrigerant flow rate by an electric signal is provided in a liquid refrigerant path forming a refrigerant cycle. It is something.

[Prior Art] A compressor that sucks in refrigerant gas, compresses it, and discharges it, a four-way valve that switches the refrigerant circulation direction, a user-side heat exchanger that uses a fluid that has undergone heat exchange with the refrigerant,
A refrigeration cycle is formed by a heat exchanger on the non-use side, etc., which exchanges heat between the refrigerant and a fluid that is not particularly used, and a single device can cool and heat the fluid on the use side. In heat pump devices, which can be switched and used at will, energy savings and improved reliability have been pursued, and recently mechanical expansion valves and capillary tubes that have traditionally been used as means for controlling refrigerant flow rate have been replaced by electric signals. Electric refrigerant flow control valves that enable precise control have come into use.

FIG. 4 is an overall configuration diagram of a conventional heat pump device that controls the flow rate of refrigerant using such an electric flow control valve. In the figure, 1 is a compressor that sucks in, compresses, and discharges refrigerant gas; 1 is a switching valve also called a four-way valve that switches the flow path of the refrigerant gas discharged from the compressor 1, and 3 is a user-side heat exchanger (hereinafter simply referred to as a four-way valve) that exchanges heat between the refrigerant gas delivered from the compressor 1 and the user-side fluid. 4 is a non-use side heat exchanger (hereinafter simply called a heat exchanger) that exchanges heat between the refrigerant gas sent from the compressor 1 and a non-use fluid such as outdoor air. ), 5 is heat exchanger 3 and 4
5a is an electric refrigerant flow control valve (hereinafter simply referred to as flow control valve) that is installed in the refrigerant path connecting the refrigerant and adjusts the refrigerant flow rate so as to change high-pressure refrigerant into cold-pressure refrigerant. An electromagnetic coil that determines the opening degree; 6 is an accumulator that separates liquid refrigerant and gas refrigerant and causes only gas refrigerant to be sucked into the compressor 1;
7 is a fan for feeding the unused fluid to the heat exchanger 4; 21, 22, and 23 are a refrigerant temperature detection device on the usage side, a refrigerant temperature detection device on the unused side, and a suction refrigerant temperature detection device, which are closely fixed to the refrigerant pipes, respectively. A device (hereinafter referred to simply as a temperature detection device), 24 controls the output value of the flow rate control valve 5, that is, the refrigerant, so that the temperature difference is maintained within a certain range based on the detected temperatures of the temperature detection devices 21, 22, and 23. Control valve drive output value calculation means 25 calculates the flow rate, and 25 supplies a current corresponding to the control valve output value to the electromagnetic coil 5a of the flow rate control valve 5 based on the calculation result of the control valve drive output value calculation means 24.
This is a control valve drive output means that adjusts the valve opening degree by controlling the flow. Note that the solid line arrow of the refrigerant feeding path indicates the refrigerant circulation direction during the heating operation for heating the user side fluid, and the dotted line arrow indicates the refrigerant circulation direction during the use side fluid cooling operation.

With the above configuration, during heating operation, the high-temperature, high-pressure gas refrigerant discharged from the compressor 1 is supplied to the heat exchanger 3 via the switching valve 2, and radiates heat to the user-side fluid to heat it and liquefy at the same time. This liquefied refrigerant is depressurized by the flow control valve 5 to become a low-temperature, low-pressure gas-liquid mixed refrigerant, and then flows into the heat exchanger 4 where it absorbs heat from the unused fluid supplied by the fan 7. Vaporize. The gas refrigerant vaporized in this way flows into the accumulator 6 via the switching valve 2, and the remaining liquid refrigerant that has not been completely vaporized in the heat exchanger 4 is separated here, and only the low-pressure gas refrigerant is transferred to the compressor 6.
is inhaled.

In addition, when the temperature of the air as the non-use side fluid is low during heating operation, moisture in the air adheres to the heat exchanger 4 in the form of frost, and when the amount of frost increases, the predetermined heat exchange performance cannot be obtained. It disappears. Therefore, the frost is removed by switching the switching valve 2 for a short time. Perform so-called defrosting operation. During this defrosting operation, the high-temperature, high-pressure gas refrigerant discharged from the compressor 1 is supplied to the heat exchanger 4 via the switching valve 2, and is liquefied at the same time as defrosting by dissipating heat to the frost attached thereto. Thereafter, the refrigerant passes through the flow control valve 5 (at this time, the opening degree of the flow control valve is fully open) in the opposite direction to the above-mentioned path, and then flows into the heat exchanger 3, absorbing heat from the user-side fluid. and vaporize. Further, the vaporized gas refrigerant flows into the accumulator 6 via the switching valve 2 and is then sucked into the compressor 1.

On the other hand, during the cooling operation, the high temperature and high pressure refrigerant gas discharged from the compressor 1 is liquefied in the heat exchanger 4, is depressurized by the flow control valve 5, and is then heat exchanged, just as in the defrosting operation described above. The fluid is cooled and vaporized at the same time by absorbing heat from the usage fluid in the container 3, and returns to the compressor 1 via the switching valve 2 and the accumulator 6.

As described above, in a heat pump device that switches between heating operation and cooling operation as necessary,
Even when the usage side fluid temperature and the non-use side fluid temperature change, it is necessary to adjust the refrigerant flow rate by adjusting the valve opening degree of the flow rate control valve 5 so that the refrigerant returning to the compressor 1 is reliably vaporized.

For this reason, for example, during heating operation, the temperature of the low-pressure gas-liquid mixed refrigerant that has passed through the flow control valve 5 is detected by the temperature detection device 22, while the temperature of the gas refrigerant flowing out from the heat exchanger 4 is detected by the temperature detection device 23. death,
The control valve drive output value calculation means 24 calculates an output value that can suppress the detected temperature difference within a certain range, and the control valve drive output means 25 changes the current flowing through the electromagnetic coil 5a so that the detected temperature difference is within a certain range. I was adjusting the opening.

This means that the refrigerant that has passed through the flow rate control valve 5 is a low-temperature, low-pressure gas-liquid mixed refrigerant, and is in a complete two-phase state, so the refrigerant temperature has reached the saturation temperature of the refrigerant pressure. Further, the refrigerant flowing into the heat exchanger 4 gradually vaporizes and reaches the outlet of the heat exchanger 4 with a pressure drop. Therefore, by assuming the pressure loss of the heat exchanger 4 and detecting the refrigerant temperature with the temperature detection device 23, the amount of superheating of the refrigerant gas at the outlet of the heat exchanger 4 can be determined.
If the temperature difference obtained by the temperature detection devices 22 and 23 is controlled within a certain range, only the low-pressure gas refrigerant having a predetermined amount of superheat can be drawn into the compressor 1.

On the other hand, during cooling operation, the heat exchanger 3 serves as a low-pressure side evaporator, so the refrigerant flow rate is adjusted such that the deviation between the temperature detected by the temperature detection device 21 and the temperature detected by the temperature detector 23 is kept within a certain range. is controlled.

[Problems to be Solved by the Invention] In the conventional heat pump device described above, the amount of superheating of the suction gas refrigerant to the compressor 1 is controlled based on the refrigerant temperature detection value of each part. When the user-side fluid temperature is low, the high pressure becomes low and the temperature detected by the temperature detection device 22 decreases, making the valve opening of the flow rate control valve 5 smaller than necessary. As a result, there was a problem in that the capacity of the compressor 1 was significantly reduced.

In addition, since the amount of superheating of the suction gas refrigerant to the compressor 1 is controlled, the temperature of the fluid on the user side increases,
On the other hand, in high compression ratio operation under conditions where the temperature of the unused fluid has decreased, the temperature of the gas refrigerant discharged from the compressor 1 will rise abnormally, resulting in poor lubrication due to carbonization of the lubricating oil in the compressor 1. There have been problems in that the compressor's life and reliability may be reduced due to overheating of the compressor drive motor.

Furthermore, when the valve opening degree of the flow rate control valve 5 is adjusted according to the detected temperature of the gas refrigerant sucked into the compressor 1, the change in the flow rate of the refrigerant due to the adjustment of the valve opening degree brings about a change in the temperature of the gas refrigerant again. Therefore, there was a problem in that the operation was difficult to stabilize, and the flow rate control valve 5 frequently opened and closed.

This invention was made to solve these problems, and it is possible to maintain a good operating condition of the compressor even when the temperature of the fluid on the user side and the fluid on the non-user side fluctuates, and there is no need for a flow control valve. The purpose of the present invention is to provide a heat pump device that can prevent frequent opening and closing operations, thereby improving the reliability and extending the life of the entire device.

[Means for Solving the Problems] A heat pump device according to the present invention includes a first heat exchanger that forms a refrigeration cycle together with a compressor and exchanges heat between a refrigerant and a fluid on a user side, and a first heat exchanger that exchanges heat between a refrigerant and a fluid on a non-user side. In a heat pump device in which a flow control valve for controlling a liquid refrigerant flow rate is provided in a path connecting a second heat exchanger that exchanges heat between fluids, a first temperature detection for detecting a refrigerant temperature discharged from the compressor. a second temperature detection device that detects the temperature of the fluid on the utilization side, a third temperature detection device that detects the temperature of the fluid on the non-utilization side, and detection of the second and third temperature detection devices. a first calculation means for calculating a control valve drive output reference value for setting the flow rate control valve to a reference opening degree based on the temperature; and a predetermined time immediately after the start of operation, during defrosting, and a predetermined time after the end of defrosting. and a second calculating means for calculating a control valve driving output correction value based on the temperature detected by the first temperature detection device to correct the control valve driving output reference value at a time excluding the temperature detected by the first temperature detecting device. The opening degree of the flow control valve is controlled based on the control valve drive output reference value, and the second calculation means is configured to control the opening degree of the flow control valve based on a control valve driving output reference value, and the second calculation means is configured to control the opening degree of the flow control valve so that the discharge refrigerant temperature of the compressor is delayed by a considerable time with respect to a change in the flow control valve. The correction interval is made longer in anticipation of the change in the value.

[Operation] In the present invention, the first calculation means calculates the control valve drive output reference value based on the usage side fluid temperature and the non-use side fluid temperature detected by the second and third temperature detection devices. By doing so, the valve opening degree is suppressed from becoming smaller than necessary in response to temperature changes in the fluid on the use side or the non-use side, thereby preventing a decrease in compressor performance.

Further, the second calculation means corrects the control valve drive output reference value based on the discharge refrigerant temperature of the compressor detected by the first temperature detection device.
Abnormal heating of the compressor discharge refrigerant temperature is prevented even under a wide range of temperature conditions.

In addition, the control valve output reference value is set to a predetermined time period immediately after the start of operation, during defrosting, and during a predetermined time period after the end of defrosting, so that the refrigerant temperature discharged from the compressor changes relative to the change in the flow rate control valve. Since the correction is performed by increasing the correction interval in anticipation of changes with a considerable time delay, this avoids frequent correction operations and at the same time allows a stable state to be reached in a short time. There is.

[Embodiment] Fig. 1 is an overall configuration diagram of an embodiment of the present invention, in which numerals 1 to 7 are exactly the same as the conventional device shown in Fig. 4, and 11, 12, 1
3 is a utilization side fluid temperature detection device, an unused side fluid temperature detection device, a compressor discharge refrigerant temperature detection device (hereinafter simply referred to as temperature detection device), and 14 is based on the detected temperature of temperature detection devices 11 and 12, Control valve drive output reference value calculation means for calculating the drive output reference value of the flow control valve 5; 15 is a temperature detection device 1;
Control valve drive output correction value calculation means for calculating the drive output correction value of the flow rate control valve 5 based on the detected temperatures of 1, 12, and 13; 16 is a control valve drive output calculation means 1;
4 and control valve drive output means 15 for controlling the valve opening degree of the flow rate control valve 5 by passing a current through the electromagnetic coil 5a such that the drive output value is calculated by the control valve drive output correction value calculation means 15. .

FIG. 2 is a circuit diagram showing the detailed configuration of the main parts of the embodiment shown in FIG.
1, memory 32, input circuit 33 and output circuit 3
4, an A/D converter 35 that converts the temperature detection value input as an analog quantity into a digital quantity and applies it to the input circuit 33;
3 is a pulse generator that applies a pulse signal of the number of pulses corresponding to the output of the output circuit 34 to the electromagnetic coil 5a;
7 is an operation switch for the heat pump device, 38 is a switch for switching the heat pump device between cooling operation and heating operation, and 41, 42, and 43 are temperature detection devices 1.
Resistors 1, 12, and 13 are connected in series to the power source, 44 and 45 are resistors connected to the power source in series with the operating switch 37 and the changeover switch 38, respectively, and 46 is the main body of the control device.

The operation of the refrigeration cycle of the heat pump device configured as described above is the same as that of the conventional device, so a description thereof will be omitted, and the control operation of the flow rate control valve 5 will be mainly explained with reference to the flowchart in FIG. This will be explained below. Note that the flowchart in Figure 3 is based on the second flowchart.
Memory 32 of the microcomputer 30 shown in the figure
This shows the portion of the program stored in the program that controls the flow rate control valve 5.

First, when the operation switch 37 is turned on as a control operation within a predetermined time from the start of operation, a signal indicating the state of the changeover switch 38 is sent to the input circuit 33.
When the input is input and the operation of compressor 1 is started,
The program is executed from step 50 in FIG. In step 50, time is counted from the start of operation, and every 30 seconds the process proceeds to step 51, but otherwise the process proceeds to step 54. Among these, in step 51, temperature detection device 1
User side fluid temperature obtained in 1 and 12 respectively
Read T _W and non-use side fluid temperature T _a , respectively. Then, in steps 52 and 53, the control drive output reference value Q _is of the flow rate control valve 5 and the compressor discharge refrigerant reference temperature T _ds are calculated based on the read fluid temperatures T _W and T _a , respectively. On the other hand, step
At 54, it is determined whether or not the defrosting operation is in progress. If the defrosting operation is in progress, the process proceeds to step 64, and if the defrosting operation is not in progress, the process proceeds to step 55.

Next, in step 55, it is determined whether the fluid temperature T _W on the user side and the fluid temperature T _a on the non-user side are within a preset range, or whether the discharge refrigerant temperature should be corrected to exceed the set range. If so, proceed to step 56. In step 56, the time is counted from the start of operation, and it is determined whether or not it is at the 4-minute increment.If it is determined at step 56 that it is not at the 4-minute increment, step 57 is performed.
The process does not proceed to step 62, and rewriting of the control valve drive output correction value Q _ic is avoided in step 62.

Then, in step 63, the control valve drive output reference value _Qis obtained in step 52 and the control valve drive output correction value _Qic stored in step 62 are added to determine the control valve drive output value _Qi . This control valve drive output value Q _i is applied to the output circuit 34 shown in FIG. 2, and the pulse generator 3 controls the current flowing through the electromagnetic coil 5a of the flow rate control valve 5. Note that if in step 55 the fluid temperature T _W on the user side and the fluid temperature T _a on the non-user side are outside the preset range, the process proceeds to step 62, so the control valve drive output correction value Q _ic is adjusted based on the compressor discharge refrigerant temperature T _d . does not change. This means that when the user-side fluid temperature T _W is not so high during heating operation, the high pressure is low and the compressor discharge refrigerant temperature T _d does not become high, so there is no need to add the control valve drive correction value Q _ic It means that.

Next, as a control operation after a predetermined period of time has elapsed from the start of operation, operations from step 50 to step 56 are performed in the same manner as the control operation within the predetermined period.
Then, the time is counted from the start of the operation, and it is determined whether or not the time is in 4-minute increments, and the process of step 57 is performed every time the time is in 4-minute increments. This step 57
Then, the compressor discharge refrigerant device T _d detected by the temperature detection device 13 is read, and in step 58 this compressor discharge refrigerant temperature T _d is compared with the compressor discharge refrigerant reference temperature T _ds calculated in step 53 above. , when T _d > T _ds +A, that is, the reference temperature
If the actual temperature T _d is higher than T _ds by A°C or more, the process proceeds to step 59, and the flow control valve 5
The control valve drive output correction value _Qic is decreased by C. Here, if the relationship T _d < T _ds + A, the process advances to step 60 and the compressor discharge refrigerant reference temperature T _ds
Furthermore, whether it is lower by B°C or not, that is,
When T _d <T _ds -B, the process proceeds to step 61, where the control valve drive output correction value _Qic is increased by C, and the process proceeds to step 62. Also, the compressor discharge refrigerant temperature T _d
is between (T _ds -B) and (T _ds +A), the process of step 60 is not executed and the control valve driving output correction value Q _ic does not change. Then, in step 62, Q _ic is memorized, and in step 63
Now, add the control valve drive output reference value Q _ic obtained in step 52 and the control valve drive output correction value Q _ic stored in step 62 to determine the control valve drive output value Q _i . Drive output value
Q _i is added to the output circuit 34 shown in FIG.
control the current flowing to the

Next, as a control operation during defrosting, steps 50 to 54 are performed in the same way as each control operation described above, and if it is determined at step 54 that defrosting operation is in progress, the process advances to step 64 and the timer count is reset. Then, in step 65, the control valve drive output value Q _i is set to a constant value D. During defrosting operation, the fluid temperature on the user side
For example, the defrosting time is shortened by setting the valve opening of the flow rate control valve 5 to be maximum, regardless of T _W and _the unused fluid temperature Ta. Also, since the processes in steps 55 to 63 are not executed during defrosting operation, the unstable compressor discharge refrigerant temperature T _d during defrosting
is read to prevent the control valve drive output correction value _Qic from being rewritten. In addition, after defrosting
During this period, the process does not proceed to step 57 based on the judgment in step 56, thereby avoiding rewriting of the control valve drive output correction value Q _ic during unstable operation after the defrosting is completed. Then, in step 66, this control valve drive output value Q _i is added to the output circuit 34 shown in FIG.
A pulse generator 36 controls the current flowing through the electromagnetic coil 5a of the flow control valve 5.

Next, the control operation after the defrosting is completed is the same as the control operation for the predetermined time from the start of operation, steps 50 to 56 and steps 62 to 66, but for 4 minutes after the defrosting is completed, step
The process does not proceed to step 57 based on the judgment in step 56, and rewriting of the control valve drive output correction value Q _ic is avoided during unstable operation after defrosting.

By the way, the function of step 56 not only prevents erroneous correction in the unstable operation range after the end of defrosting, but also prevents correction in the unstable operation range immediately after the start of operation. Furthermore, while the control valve drive output reference value Q _is is rewritten every 30 seconds, the control valve drive output correction value Q _ic based on the compressor discharge refrigerant temperature T _d is rewritten every 4 minutes. This is to prevent unnecessary opening and closing operations of the flow rate control valve 5. That is, since the compressor discharge refrigerant temperature T _d changes with a considerable time delay in response to a change in the flow rate control valve 5, the correction interval is lengthened in consideration of this delay time, thereby reducing frequent correction operations. At the same time, we aim to reach a stable state in a short time.

Note that the calculation cycle of the control valve drive output reference value Q _is and the calculation cycle of the control valve drive output correction value Q _ic are not limited to the above-mentioned 30 seconds and 4 minutes, respectively, but can be changed as appropriate depending on the heating and cooling loads. However, by setting the latter cycle to be much larger than the former, it is possible to prevent the flow rate control valve from opening and closing unnecessarily frequently.

[Effects of the Invention] As is clear from the above description, according to the present invention, the first calculation means calculates the control valve drive output reference value based on the detected utilization side fluid temperature and non-utilization side fluid temperature. Since the calculation is performed, the compressor can be made to respond appropriately to the temperature change of the fluid on the usage side or the fluid on the non-use side, and the operating condition of the compressor can always be maintained in a good condition.

Furthermore, since the second calculation means corrects the control valve drive output reference value based on the detected compressor discharge refrigerant temperature, abnormal overheating of the compressor discharge refrigerant temperature can be prevented, and Even in the case of liquid backup operation, it is possible to detect an abnormal drop in the temperature of the discharged refrigerant and return to normal operation, thereby improving the reliability of the heat pump.

Furthermore, the control valve output reference value is set at a time excluding a predetermined time immediately after the start of operation, during defrosting, and a predetermined time after the end of defrosting, so that the refrigerant temperature discharged from the compressor responds to a change in the flow rate control valve. Since the correction is performed by increasing the correction interval in anticipation of changes with a considerable time delay, this avoids frequent correction operations and at the same time makes it possible to reach a stable state in a short time. can.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of an embodiment of the present invention, Fig. 2 is a circuit diagram showing the detailed configuration of the main part of the embodiment, and Fig. 3 is a flowchart for explaining the operation of the embodiment. , FIG. 4 is an overall configuration diagram of a conventional heat pump device. In the figure, 1 is a compressor, 2 is a switching valve, 3 is a heat exchanger on the use side, 4 is a heat exchanger on the non-use side, 5 is an electric flow control valve, 5a is an electromagnetic coil, 6 is an accumulator, and 11 is a use side heat exchanger. 12 is a side fluid temperature detection device, 13 is a discharge refrigerant temperature detection device. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1 A first heat exchanger that forms a refrigeration cycle with the compressor and exchanges heat between the refrigerant and the fluid on the user side, and a second heat exchanger that exchanges heat between the refrigerant and the fluid on the non-user side.
In the heat pump device, a flow rate control valve for controlling the flow rate of liquid refrigerant is provided in a path connecting the heat exchanger to the heat exchanger.
a second temperature detection device for detecting the temperature of the fluid on the usage side, a third temperature detection device for detecting the temperature of the fluid on the non-utilization side, and a second temperature detection device for detecting the temperature of the fluid on the non-utilization side;
and based on the detected temperature of the third temperature detection device,
a first calculation means for calculating a control valve drive output reference value for setting the flow rate control valve to a reference opening degree; and a time period excluding a predetermined time immediately after the start of operation, a predetermined time during defrosting, and a predetermined time after the end of defrosting. and a second calculation means for calculating a control valve drive output correction value based on the temperature detected by the first temperature detection device to correct the control valve drive output reference value, the corrected control valve drive output being corrected. The opening degree of the flow control valve is controlled by the output reference value, and the second calculation means is configured to control the temperature of the refrigerant discharged from the compressor to change with a considerable time delay with respect to the change in the flow control valve. A heat pump device characterized in that the correction interval is lengthened in anticipation of the