JP2006078146A - Heat pump, floor heating device, and air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To estimate delivery pressure of a compressor and to keep the delivery pressure of the compressor to be a reference value or lower, using only hardware originally disposed in a heat pump without using an expensive component such as a pressure switch. <P>SOLUTION: A current detector 29 for detecting magnitude of a driving current of the compressor is provided. A current control section 28 stores the limit of the driving current in a form of a function varied by rotation speed of the compressor, and, when the driving current exceeds the limit, issues a frequency limit command for restricting the rotation speed of the inverter driving type compressor to a compressor operation frequency determining means 25. Alternatively it issues an opening correcting command for adjusting the opening of the expansion valve in the opening direction to an expansion valve opening determining means 27. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat pump and a floor heating device provided with a heat pump, and an air conditioner, and in particular, control means for preventing a high-load operation of a compressor of the heat pump and controlling the compressor outlet refrigerant temperature to an efficient temperature. It is about.

  A heat pump is a device that extracts heat from a low-temperature heat source by applying compression, condensation, decompression, and evaporation operations to the refrigerant in the refrigerant circuit. In general, the amount of heat taken out by the heat pump is larger than the amount of heat for driving the heat pump (mainly the power of the compressor). Therefore, when the heat pump is used for hot water supply equipment or heating equipment, a large amount of heat can be taken out with a small amount of heat consumption. Therefore, it is less consumption of kerosene than boiling kerosene with a boiler and driving the heat pump with kerosene to obtain heat from a low heat source (usually using outside air as a low heat source) to boil hot water. .

  For this reason, various types of water heaters using heat pumps have been proposed today. For example, Patent Document 1 discloses a method of switching between a refrigerant flow in a refrigerant circuit connected to a compressor and an outdoor heat exchanger, an indoor heat exchanger, a regenerative heat storage tank, and a hot water supply heat exchanger. A multi-function heat pump system that performs cold storage is disclosed.

  In heat pumps, it is required to maximize the ratio (COP: Coefficient of performance) obtained by dividing the amount of heat carried from a low heat source to the object to be heated by the power that drives the heat pump. The refrigerant temperature at the compressor outlet (optimum compressor outlet temperature) is selected, and the temperature of the refrigerant at the compressor outlet is controlled to be kept at the optimum compressor outlet temperature by adjusting the opening of the expansion valve.

  In general, heat pumps use outside air as a low heat source, but the outside air temperature varies greatly depending on the season. As the outside air temperature rises, the refrigerant temperature at the compressor inlet rises, and in order to keep the compressor outlet temperature constant, the refrigerant vapor pressure at the compressor outlet, i.e., the discharge pressure of the compressor, must be increased. Don't be. However, since the discharge pressure of the compressor is limited by the mechanical strength of the compressor, simply controlling the refrigerant temperature at the compressor outlet to the optimum compressor outlet temperature may cause damage to the compressor. End up.

  Patent Document 2 discloses a heat pump type hot water supply that includes a pressure switch at the outlet of the compressor, detects the discharge pressure of the compressor, and lowers the control target of the compressor outlet temperature when the discharge pressure exceeds the reference pressure. An apparatus is disclosed.

JP 11-270920 A JP 2001-263801 A

  However, when the control target of the compressor outlet refrigerant temperature is set low, there is a problem that COP deteriorates. Moreover, since the pressure switch is expensive, there is a problem that providing the pressure switch in the heat pump leads to an increase in cost. Further, from the viewpoint of improving reliability, it is not preferable to increase the number of components.

  Therefore, an object of the present invention is to estimate the discharge pressure of the compressor by using only the hardware originally provided in the heat pump without using expensive parts such as a pressure switch, and to reduce the discharge pressure of the compressor. By maintaining the temperature below the reference value and controlling the refrigerant temperature at the compressor outlet to an efficient temperature, a heat pump that is inexpensive and highly reliable, has a good COP, and a floor heating device and an air conditioner equipped with the heat pump are realized. There is to do.

  The configuration of the heat pump according to the present invention includes an inverter-driven compressor, a hot water refrigerant heat exchanger that cools refrigerant discharged from the inverter-driven compressor, and an expansion valve that depressurizes the refrigerant that has exited the heat exchanger. And an air refrigerant heat exchanger for heating the refrigerant that has exited the expansion valve and returning it to the inverter-driven compressor, and the expansion so that the temperature of the refrigerant at the outlet of the inverter-driven compressor is constant. In the heat pump having a control means for adjusting the opening of the valve, the heat pump includes a current detection unit that detects the magnitude of the drive current of the inverter-driven compressor, and the control means limits the drive current to the inverter-driven type. It is stored in the form of a function that changes according to the rotational speed of the compressor, and when the drive current exceeds the limit, the rotational speed of the inverter-driven compressor is limited or the expansion And adjusting the direction of opening the opening of the valve.

According to this configuration, the discharge pressure is estimated based on the rotation speed and drive current of the inverter-driven compressor, and the rotation speed limit or the expansion valve opening is set so that the discharge pressure does not exceed the limit. Since the opening direction is adjusted, an inexpensive and highly reliable heat pump can be provided.

The floor heating apparatus according to the present invention includes an inverter driven compressor, a hot water refrigerant heat exchanger that cools the refrigerant discharged from the inverter driven compressor with hot water for hot water supply, and the hot water refrigerant heat exchanger. An expansion valve that depressurizes the refrigerant, an air refrigerant heat exchanger that heats the refrigerant exiting the expansion valve with outside air and returns the refrigerant to the inverter-driven compressor, and the refrigerant at the outlet of the inverter-driven compressor In the floor heating apparatus having a floor heating panel that circulates the hot water for hot water supply between the control means for adjusting the opening of the expansion valve so that the temperature of the hot water becomes constant, and the hot water refrigerant heat exchanger, the inverter A current detector for detecting the magnitude of the drive current of the drive compressor, wherein the control means stores the limit of the drive current in the form of a function that changes according to the rotational speed of the inverter drive compressor; , When the drive current exceeds the limit, and adjusting the rotational speed of the inverter-driven compressor limits, or in the direction of opening the opening degree of the expansion valve.

According to this configuration, the discharge pressure is estimated based on the rotation speed and drive current of the inverter-driven compressor, and the rotation speed limit or the expansion valve opening is set so that the discharge pressure does not exceed the limit. Since the opening direction is adjusted, an inexpensive and highly reliable floor heating apparatus can be provided.

The configuration of the air conditioner according to the present invention includes an inverter-driven compressor, a hot water refrigerant heat exchanger that cools a refrigerant discharged from the inverter-driven compressor with hot water for hot water supply, and the heat exchanger that exits the heat exchanger. Between the first expansion valve that decompresses the refrigerant, the air refrigerant heat exchanger that heats the refrigerant that exits the expansion valve with outside air and returns the refrigerant to the inverter-driven compressor, and the hot water refrigerant heat exchanger Floor heating panel that circulates the hot water for hot water supply, branch piping that branches the refrigerant discharged from the inverter-driven compressor, and indoor heat that exchanges heat between the refrigerant flowing from the branch piping and indoor air An exchanger, a second expansion valve for depressurizing the refrigerant exiting the indoor heat exchanger, a pipe for flowing the refrigerant flowing out of the second expansion valve to the air refrigerant heat exchanger, and the inverter drive Compressor outlet In the air conditioner having a control means for adjusting the opening of the expansion valve so that the temperature of the refrigerant in the chamber is constant, the air conditioner includes a current detection unit that detects the magnitude of the drive current of the inverter-driven compressor, The control means stores the limit of the drive current in the form of a function that changes according to the rotation speed of the inverter-driven compressor, and when the drive current exceeds the limit, the rotation speed of the inverter-driven compressor is stored. The restriction or the opening degree of the expansion valve is adjusted in the opening direction.

According to this configuration, since the discharge pressure is estimated and the rotation speed limit or the opening degree of the expansion valve is adjusted to open so that the discharge pressure does not exceed the limit, the air conditioning is inexpensive and reliable. Since the apparatus can be provided and the compressor outlet refrigerant temperature is also constant, efficient heating operation is always possible.

As described above, according to the present invention, the discharge pressure is estimated from the rotation speed of the compressor and the drive current, and the rotation speed limit or the expansion valve opening is opened so that the discharge pressure does not exceed the limit. Since the adjustment is made in the direction, damage to the compressor can be avoided even when the outside air temperature is high or in a high load situation where the set heating temperature is high. In addition, since only the hardware that the heat pump originally has is used without using expensive parts such as pressure switches, a highly reliable heat pump, a floor heating device equipped with a heat pump, and an air conditioner can be realized at low cost. can do.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a circuit diagram of an air conditioner according to an embodiment of the present invention.

  In FIG. 1, 1 is an air conditioner. The air conditioner 1 can switch the cooling mode and the heating mode by switching the flow direction of the refrigerant by the four-way valve 2, and the figure shows the heating mode, that is, the state in which the air conditioner 1 is used as a heater. The air conditioner 1 also includes a floor heating panel 3 through which hot water heated by the heat of the refrigerant circulates, and an indoor unit 4 that directly warms indoor air using the heat of the refrigerant. In FIG. 1, for convenience of explanation, the refrigerant flow is indicated by a broken line, and the hot water flow is indicated by a one-dot chain line.

  First, a circuit related to the floor heating panel 3 will be described. Reference numeral 5 denotes a compressor that is driven by an inverter motor 6 to compress refrigerant vapor, and has a first thermistor 7 that detects the temperature of the refrigerant at its discharge port. The flow of the high-temperature refrigerant exiting the compressor 5 is divided into a flow going to the indoor unit 4 and a flow going to the hot water-refrigerant heat exchanger 9 at the branch pipe 8.

The hot water-refrigerant heat exchanger 9 is a device for exchanging heat between the refrigerant and hot water. The hot water heated by the heat of the refrigerant and exiting the hot water-refrigerant heat exchanger 9 is stored in the water supply tank 10 and circulated. It is sent to the floor heating panel 3 by the pump 11, circulates in the floor heating panel 3, and returns to the hot water-refrigerant heat exchanger 9. In this embodiment, the temperature of the hot water is 40 ° C. at the outlet of the hot water-refrigerant heat exchanger 9, 35 ° C. in the floor heating panel 3, and 30 ° C. when returning to the hot water-refrigerant heat exchanger 9. Designed. The temperature of the refrigerant is designed to be 70 ° C. at the discharge port of the compressor 5, 65 ° C. at the inlet of the hot water-refrigerant heat exchanger 9, and 50 ° C. at the outlet. The refrigerant temperature 70 ° C. at the discharge port of the compressor 5 is a temperature determined so that the combination of the efficiency of the compressor 5 and the hot water-refrigerant heat exchanger 9 is optimized. Reference numeral 12 denotes a second thermistor that detects the temperature of the hot water returned from the floor heating panel 3 to the hot water-refrigerant heat exchanger 8.

  The refrigerant that has exited the hot water-refrigerant heat exchanger 9 is reduced in pressure through the first electronic expansion valve 13 to become a low-temperature liquid, and merges with the refrigerant that has returned from the indoor unit 4 through the merge pipe 14 to the outdoor unit. 15 flows. The outdoor unit 15 is a heat exchanger that performs heat exchange between the refrigerant and outdoor air. The first electronic expansion valve 13 is an expansion valve whose opening degree can be freely adjusted by electronic control, and the discharge pressure of the compressor 5 increases or decreases depending on the opening degree.

  The low-temperature liquid refrigerant that has entered the outdoor unit 15 is heated by the outside air to become vapor, passes through the four-way valve 2, and returns to the compressor 5.

  Next, a circuit related to the indoor unit 4 will be described. The indoor unit 4 is an indoor heat exchanger that exchanges heat between the refrigerant and indoor air, and the high-temperature refrigerant flowing from the branch pipe 8 to the indoor unit 4 is cooled by exchanging heat with the indoor air. The refrigerant is liquefied, depressurized through the second electronic expansion valve 16, becomes low temperature, merges with the refrigerant returned from the hot water-refrigerant heat exchanger 9 through the merge pipe 14, and flows to the outdoor unit 15.

  Here, the control apparatus of the air conditioning apparatus 1 is demonstrated. FIG. 2 is a control block diagram of the air conditioner 1. In FIG. 2, reference numeral 21 denotes a control device for the air conditioner 1. The control device 21 inputs the heating temperature desired by the user, the temperature of the hot water returned from the floor heating panel 3, the temperature of the refrigerant at the discharge port of the compressor 5, and the drive current of the inverter motor 6 for driving the compressor 5. The control device controls the operation of the air conditioner 1 by outputting the operating frequency of the inverter motor 6 and the opening degrees of the first and second electronic expansion valves 13 and 16.

Reference numeral 22 denotes a remote controller. When the user inputs a desired heating temperature to the remote controller 22, the heating temperature is transmitted to the set temperature determination means 23. The set temperature determination means 23 sets a target value (set temperature) of the return hot water temperature (the temperature of the hot water returned from the floor heating panel 3 to the hot water-refrigerant heat exchanger 9) according to the heating temperature, and adjusts the temperature. Tell the control unit 24. The measured value of the return hot water temperature measured by the second thermistor 12 is also input to the temperature control unit 24. The temperature control unit 24 compares the target value (set temperature) with the measured value, and transmits the frequency (operating frequency) instructed to the inverter motor 6 to the compressor operating frequency determining means 25.

Reference numeral 26 denotes a discharge temperature control unit that controls the temperature (discharge temperature) of the refrigerant at the discharge port of the compressor 5. As described above, since the optimum temperature (discharge temperature) of the refrigerant at the discharge port of the compressor 5 is 70 ° C., the discharge temperature control unit 26 causes the discharge temperature measured by the first thermistor 7 to be 70 ° C. In addition, the opening degree of the first and second electronic expansion valves 13 and 16 is increased or decreased. That is, an instruction is given to the expansion valve opening determining means 27 to increase the opening when the discharge temperature is higher than 70 ° C. and to decrease the opening when the discharge temperature is lower than 70 ° C.

  Reference numeral 28 denotes a current control unit. The current control unit 28 stores the limit value of the drive current of the inverter motor 6 in the form of a function of the operation frequency, and when the drive current of the inverter motor 6 exceeds the limit value, the first and second electronic expansion valves 13 are stored. , 16 is opened or the operating frequency of the inverter motor 6 is lowered to reduce the drive current of the inverter motor 6. The current control unit 28 includes a current value from a current detection unit 29 that measures a drive current (actual current) flowing through the inverter motor 6, and a refrigerant temperature (discharge temperature) from the first thermistor 7 to the discharge port of the compressor 5. ), The opening degree of the first and second electronic expansion valves 13 and 16 is input from the expansion valve opening degree determining means 27, and the operating frequency of the inverter motor 6 is input from the compressor operating frequency determining means 25, respectively. Upon receiving these inputs, the current control unit 28 opens a frequency limit command for limiting the operating frequency of the inverter motor 6 to the compressor operating frequency determining means 25 and opens the first and second electronic expansion valves 13 and 16. A degree correction command is output to the expansion valve opening determination means 27, respectively. Details of the control executed by the current control unit 28 will be described later.

  Reference numeral 30 denotes a compressor control unit. The compressor control unit 30 is an inverter that receives an operation frequency command from the compressor operation frequency determining means 25 and supplies current to the inverter motor 6 so as to reach the operation frequency.

  Reference numeral 31 denotes an expansion valve control unit. The expansion valve control unit 31 is a control device that opens and closes the first and second electronic expansion valves 13 and 16 in response to an expansion valve opening command from the expansion valve opening determining means 27.

FIG. 3 is a flowchart illustrating the current control executed by the current control unit 28. Hereinafter, the details of the current control will be described with reference to the step numbers attached to the drawings.

(STEP 1) The drive current (actual current value) of the inverter motor 6 detected by the current detector 29 is compared with the limit current value, and if the actual current value exceeds the limit current value, the process proceeds to STEP 2 and the actual current value If NO is less than the limit current value, the process proceeds to STEP9.
Here, the limit current value is a function that varies depending on the operating frequency of the inverter motor 6. Specifically, the current control unit 28 stores in advance a correspondence table of 12 stages of operation frequencies and the corresponding limit current values, and the current control unit 28 is input from the compressor operation frequency determining means 25. The limiting current value is determined by applying the operation frequency of the inverter motor 6 to the correspondence table.

  The correspondence table is created by experimentally or calculating a drive current value that causes the discharge pressure of the compressor 5 to be a certain value or less for each operating frequency.

(STEP 2) If the calculation cycle has timed up, proceed to STEP 3, and if it has not timed up, end without doing anything.

(STEP 3) The calculation cycle is set to 20 seconds, and the process proceeds to STEP 4.

(STEP 4) If the opening degree of the first and second electronic expansion valves 13 and 16 has reached the upper limit (because the first and second electronic expansion valves 13 and 16 cannot be opened any more), STEP 5 If the opening does not reach the upper limit, the process proceeds to STEP6.

(STEP 5) A frequency limit command for lowering the limit frequency of the inverter motor 6 by 3.3 Hz is given to the compressor operating frequency determining means 25 and the process is terminated (in response to this, the compressor operating frequency determining means 25 determines the operating frequency of the inverter motor). Is given to the compressor control unit 30).

(STEP 6) The refrigerant temperature (discharge temperature) at the outlet of the compressor 5 measured by the first thermistor 7 and the optimum compressor outlet temperature (target temperature = 70 ° C.) are compared, and the discharge temperature is the target temperature. If not, the process proceeds to STEP7, and if the discharge temperature is equal to or higher than the target temperature, the process proceeds to STEP8.

(STEP 7) If the operating frequency of the inverter motor 6 exceeds the lower limit frequency, proceed to STEP 5, and if the operating frequency is equal to or lower than the lower limit frequency, proceed to STEP 8.

(STEP 8) An opening correction command for opening the first and second electronic expansion valves 13 and 16 by 4 pulses is output to the expansion valve opening determining means 27, and the process ends.

(STEP 9) The opening correction command for opening the opening of the first and second electronic expansion valves 13 and 16 is cleared (the opening correction command output in STEP 8 is set to 0), and the process proceeds to STEP 10.

(STEP 10) If the calculation cycle has timed up, proceed to STEP 11, and if it has not timed up, end without doing anything.

(STEP 11) The drive current (actual current) of the inverter motor 6 detected by the current detector 29 is compared with a value obtained by subtracting 0.1 A from the limit current value, and the actual current is (limit current value−0.1 A). If it is above, proceed to STEP12, and if the actual current is less than (limit current value−0.1 A), proceed to STEP13.

(STEP 12) The calculation cycle is set to 20 seconds and the process ends.

(STEP 13) A frequency limit command for raising the limit frequency of the inverter motor by 2 Hz is given to the compressor operating frequency determination means 25, and the process proceeds to STEP 14.

(STEP 14) The calculation cycle is set to 60 seconds and the process ends.

It is a circuit diagram of the air harmony device concerning the example of the present invention of the present invention. It is a control block diagram of the air conditioning apparatus which concerns on the Example of this invention. 4 is a flowchart illustrating current control executed by a current control unit 28.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus 2 Four-way valve 3 Floor heating panel 4 Indoor unit 5 Compressor 6 Inverter motor 7 1st thermistor 8 Branch pipe 9 Hot water-refrigerant heat exchanger 10 Water supply tank 11 Circulation pump 12 2nd thermistor 13 1st Electronic expansion valve 14 merging pipe 15 outdoor unit 16 second electronic expansion valve 21 controller 22 remote controller 23 set temperature determining means 24 temperature control section 25 compressor operating frequency determining means 26 discharge temperature control section 27 expansion valve opening Determining means 28 Current controller 29 Current detector 30 Compressor controller 31 Expansion valve controller

Claims (3)

An inverter-driven compressor, a hot water refrigerant heat exchanger that cools the refrigerant discharged from the inverter-driven compressor, an expansion valve that depressurizes the refrigerant that has exited the heat exchanger, and the expansion valve that has exited the expansion valve An air refrigerant heat exchanger for heating the refrigerant and returning it to the inverter-driven compressor, and a control means for adjusting the opening of the expansion valve so that the temperature of the refrigerant at the outlet of the inverter-driven compressor is constant In a heat pump having
A current detector for detecting the magnitude of the drive current of the inverter-driven compressor; and the control means stores the limit of the drive current in the form of a function that varies depending on the rotational speed of the inverter-driven compressor. When the drive current exceeds the limit, the rotation speed of the inverter-driven compressor is limited or the opening degree of the expansion valve is adjusted to open. An inverter-driven compressor, a hot-water refrigerant heat exchanger that cools the refrigerant discharged from the inverter-driven compressor with hot water for hot water supply, an expansion valve that depressurizes the refrigerant that exits the hot water refrigerant heat exchanger, and An air refrigerant heat exchanger that heats the refrigerant that has exited the expansion valve with outside air and returns the refrigerant to the inverter-driven compressor, and the expansion valve so that the temperature of the refrigerant at the outlet of the inverter-driven compressor is constant In the floor heating apparatus having a floor heating panel for circulating the hot water for hot water supply between the control means for adjusting the opening degree of the hot water refrigerant heat exchanger,
A current detector for detecting the magnitude of the drive current of the inverter-driven compressor; and the control means stores the limit of the drive current in the form of a function that varies depending on the rotational speed of the inverter-driven compressor. When the drive current exceeds the limit, the number of revolutions of the inverter-driven compressor is limited or the opening degree of the expansion valve is adjusted to open. An inverter-driven compressor, a hot water refrigerant heat exchanger that cools the refrigerant discharged from the inverter-driven compressor with hot water for hot water supply, and a first expansion valve that depressurizes the refrigerant that has exited the heat exchanger, An air refrigerant heat exchanger that heats the refrigerant that has exited the expansion valve with outside air and returns the refrigerant to the inverter-driven compressor, and a floor heating panel that circulates the hot water for hot water supply between the hot water refrigerant heat exchanger and A branch pipe for branching the refrigerant discharged from the inverter-driven compressor, an indoor heat exchanger for exchanging heat between the refrigerant flowing from the branch pipe and indoor air, and an outlet from the indoor heat exchanger. A second expansion valve for depressurizing the refrigerant, a pipe for flowing the refrigerant flowing out of the second expansion valve to the air refrigerant heat exchanger, and a temperature of the refrigerant at an outlet of the inverter-driven compressor. Become constant In the air conditioning apparatus having a control means for adjusting the opening of sea urchin said expansion valve,
A current detector for detecting the magnitude of the drive current of the inverter-driven compressor; and the control means stores the limit of the drive current in the form of a function that varies depending on the rotational speed of the inverter-driven compressor. When the drive current exceeds the limit, the rotation speed of the inverter-driven compressor is limited or the opening degree of the expansion valve is adjusted to open.

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