Heat medium circulation type heating heat pump device

Abstract

To provide a heat medium circulation type heating heat pump device that can more reliably detect dropout of a temperature sensor for detecting the discharge temperature of a compressor by using an existing temperature sensor in the heat medium circulation type heating heat pump device.SOLUTION: A heat medium circulation type heating heat pump 1 includes: a refrigeration cycle 5 comprising a compressor 11, a first heat exchanger 13, an expansion valve 15, and a second heat exchanger 16; a use-side apparatus 27; a heat medium flow passage 58 that connects the first heat exchanger 13 of the refrigeration cycle 5 and the use-side apparatus 27 to allow a heat medium to circulate; a discharge temperature sensor 42 that is provided in piping on the discharge side of the compressor 11 for detecting a discharge temperature; a refrigerant outlet side temperature sensor 43 for detecting the temperature of a refrigerant after heat exchange which flows out from the first heat exchanger 13; and a control unit 29 that, when a difference obtained by subtracting the temperature of the refrigerant after heat exchange from the discharge temperature is smaller than a predetermined temperature value after elapse of a predetermined waiting time from start-up of the compressor 11, determines that the discharge temperature sensor 42 drops out from the piping on the discharge side of the compressor 11, and stops the compressor 11.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment according to the present invention relates to a heat medium circulation type heat pump device. [Background technology]

[0002] In a refrigeration system equipped with a heat pump refrigeration cycle, if the discharge pressure of the compressor becomes high above a predetermined value, there is a risk that the refrigeration cycle components such as the compressor will break down. Therefore, the discharge pressure of the compressor is detected by a pressure sensor and the compressor is stopped in advance. However, a pressure sensor is expensive and needs to be connected to the refrigeration cycle, which makes it difficult to manufacture and complicates the cycle configuration. Therefore, a refrigeration system is known in which, although there is a slight time delay due to a temperature response delay, when the discharge temperature of the compressor, which is basically approximately proportional to the discharge pressure of the compressor, becomes a predetermined temperature or higher, it is determined that the discharge pressure of the compressor has abnormally increased and the operation of the compressor is stopped. In such a refrigeration system, the discharge temperature of the compressor is generally detected by a discharge temperature sensor such as a thermistor attached to the discharge pipe of the compressor. However, the discharge temperature sensor is attached and detached to the outer periphery of the cylindrical discharge pipe, and is mechanically fixed by a clip or the like so that it can be thermally conducted from the discharge pipe. For this reason, there is a risk that this temperature sensor will fall off the discharge pipe due to vibration or disturbance. If the sensor falls off the discharge pipe, the discharge temperature of the compressor cannot be detected, and the abnormally high pressure state cannot be correctly determined. For this reason, it has been considered to provide an abnormality processing means for the refrigeration system that determines whether the discharge temperature sensor has fallen off. If the difference between the detection value of the discharge temperature sensor at the start of the compressor and the detection value of the discharge temperature sensor a predetermined time after the start is equal to or less than a predetermined temperature, this abnormality processing means detects the discharge temperature sensor as falling off and causes the refrigeration system to stop abnormally. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-99543 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional refrigeration devices detect the detachment of the discharge temperature sensor based on the detection value of the discharge temperature sensor and its change over time. However, if the discharge temperature sensor falls off, it falls near the compressor. Therefore, the detected temperature of the discharge temperature sensor is affected by the temperature rise of the compressor surface due to the operation of the compressor. Therefore, even if the discharge temperature sensor falls off, the detected temperature of the discharge temperature sensor rises due to the temperature rise of the compressor, and depending on the ambient temperature of the discharge temperature sensor before the compressor starts, i.e., the outside air temperature, the position where the discharge temperature sensor fell off, and the temperature rise of the compressor, the detachment of the discharge temperature sensor cannot be detected, which may cause a breakdown of the refrigeration cycle parts.

[0005] Therefore, an object of the present invention is to provide a heat medium circulation type heating heat pump device that can more reliably detect the loss of a discharge temperature sensor that detects the discharge temperature of the compressor by using an existing temperature sensor in the heat medium circulation type heating heat pump device. [Means for solving the problem]

[0006] In order to solve the above problems, a heat medium circulation type heating heat pump device according to an embodiment of the present invention has a compressor, a first heat exchanger, a throttling device, and a second heat exchanger. The refrigerant discharged from the compressor is circulated through a refrigerant pipe in the order of the first heat exchanger, the expansion device, and the second heat exchanger. a refrigeration cycle having a heat exchanger and a utilization side device, the first heat exchanger of the refrigeration cycle being connected to the utilization side device; The utilization side device is provided with a refrigerant heated by heat exchange with the refrigerant in the first heat exchanger. A medium flow path for circulating a heat medium and a discharge side of the compressor The refrigerant Installed in the piping The compressor a discharge temperature sensor for detecting a discharge temperature of the heat-exchanged gas flowing out of the first heat exchanger; The above The compressor is provided with a first heat exchanger outlet side temperature sensor that detects the temperature of the refrigerant, and a control unit that stops the compressor when a difference between the discharge temperature and the refrigerant temperature after the heat exchange is smaller than a predetermined temperature value after a predetermined standby time has elapsed since the compressor is started. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram of a heat medium circulation type heat pump device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a TH diagram of the heat medium circulation type heating heat pump device according to the embodiment of the present invention. [Diagram 3] 4 is a graph showing an example of a temperature transition from before and after the start of the heat medium circulation type heat pump device according to the embodiment of the present invention to immediately before stable operation. [Figure 4] 10 is a graph showing another example of a temperature transition from before and after the start of the heat medium circulation type heat pump device according to the embodiment of the present invention to immediately before stable operation. [Diagram 5] 4 is a control flowchart relating to a discharge temperature sensor executed by the heat medium circulation type heat pump device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of a heat medium circulation type heating heat pump device according to the present invention will be described with reference to Fig. 1 to Fig. 5. In addition, the same reference numerals are used to denote the same or corresponding configurations in the multiple drawings.

[0009] FIG. 1 is a block diagram of a heat medium circulation type heat pump device according to an embodiment of the present invention.

[0010] As shown in FIG. 1, a heat medium circulation type heating heat pump device 1 according to this embodiment includes a heat source unit 2 that exchanges heat between a circulating refrigerant and outside air and between the circulating refrigerant and the circulating heat medium, and a load unit 3 that circulates and utilizes the heat medium heated by the heat source unit 2.

[0011] In the following description, the heat medium circulation type heating heat pump device 1 will be simply referred to as the "heat pump device 1".

[0012] The heat source unit 2 includes a refrigeration cycle 5. The refrigeration cycle 5 includes a compressor 11, a four-way valve 12, a first heat exchanger 13, an expansion valve 15 as a throttling device, a second heat exchanger 16, and refrigerant piping 17 that sequentially connects the compressor 11, the four-way valve 12, the first heat exchanger 13, the expansion valve 15, and the second heat exchanger 16. The refrigeration cycle 5 circulates a refrigerant through the compressor 11, the four-way valve 12, the first heat exchanger 13, the expansion valve 15, and the second heat exchanger 16 via the refrigerant piping 17. The refrigerant circulating through the refrigeration cycle 5 is, for example, R410A or R32.

[0013] When the heat medium is heated, the refrigeration cycle 5 sets the flow direction of the refrigerant flowing through the refrigerant pipe 17 so that the first heat exchanger 13 functions as a condenser and the second heat exchanger 16 functions as an evaporator. That is, the refrigeration cycle 5 switches the four-way valve 12 so that the refrigerant circulates in the order of the compressor 11, the four-way valve 12, the first heat exchanger 13, the expansion valve 15, the first heat exchanger 13, the four-way valve 12, and the compressor 11.

[0014] The compressor 11 includes a high-pressure container, a compression mechanism housed in the high-pressure container, and a DC brushless motor housed in the high-pressure container for driving the compression mechanism. The compressor 11 compresses and pressurizes the refrigerant with the compression mechanism, and discharges the refrigerant in a high-temperature, high-pressure state. The compressor 11 can change its operating frequency by known inverter control. By increasing the rotation speed of the compressor 11, the amount of heat transferred to the high-temperature portion increases, and by decreasing the rotation speed, the amount of heat transferred to the high-temperature portion decreases.

[0015] The first heat exchanger 13 is also called a water heat exchanger. The first heat exchanger 13 exchanges heat between the refrigerant circulating through the heat source unit 2 and the heat medium circulating through the load unit 3.

[0016] The expansion valve 15 is, for example, an electronic expansion valve (Pulse Motor Valve: PMV). The opening degree of the expansion valve 15 is adjusted according to the state of the refrigeration cycle. The expansion valve 15 is provided in series in the refrigerant pipe 17 between the first heat exchanger 13 and the second heat exchanger 16. The expansion valve 15 reduces the pressure of the refrigerant to allow the refrigerant to flow out in a low-temperature and low-pressure state.

[0017] The second heat exchanger 16 is also called an air heat exchanger. The second heat exchanger 16 exchanges heat between the refrigerant in the refrigerant pipe 17 and the atmosphere of the second heat exchanger 16, which is usually the outside air.

[0018] The heat source unit 2 also includes a blower fan 21 that is installed near the second heat exchanger 16 to draw in air from the second heat exchanger 16 side and blow out the outside air after heat exchange in the second heat exchanger 16, a plurality of temperature sensors that detect the temperatures of each part of the refrigeration cycle 5, a three-phase inverter device 25 that is connected to a commercial AC power source E and drives the DC brushless motor of the compressor 11 at a variable speed, a controller 26 which is an input device that accepts operations by a user, a display unit 28 that displays the settings and operating states as operating conditions of the heat source unit 2 and the user side equipment 27, and a control unit 29 that controls the operation of the heat source unit 2 and the user side equipment 27 based on the operation of the controller 26.

[0019] The multiple temperature sensors provided in various parts include a suction temperature sensor 41 provided in the refrigerant piping 17 on the suction side of the compressor 11 to detect the temperature TS of the refrigerant sucked into the compressor 11, a discharge temperature sensor 42 attached to the refrigerant piping 17 on the discharge side of the compressor 11 as in the conventional manner and removably attached with a clip or the like to detect the temperature TD of the refrigerant discharged from the compressor 11, a refrigerant outlet side temperature sensor 43 provided in the refrigerant piping 17 to detect the temperature TC (condensation temperature) of the refrigerant after heat exchange flowing out of the first heat exchanger 13, a refrigerant temperature sensor 45 provided in the second heat exchanger 16 to detect the temperature TE (evaporation temperature) of the refrigerant circulating through the second heat exchanger 16, and an outside air temperature sensor 46 to detect the outside air temperature TO.

[0020] The outside air temperature sensor 46 is provided in the second heat exchanger 16. The outside air temperature sensor 46 is disposed upstream of the second heat exchanger 16 in the blowing direction of the blower fan 21 in order to accurately detect the outside air temperature.

[0021] It should be noted that the heat source unit 2 is not provided with a pressure sensor for detecting the pressure of the refrigerant circulating in the refrigeration cycle 5.

[0022] The load unit 3 includes a first heat exchanger 13 shared by the load unit 3 and the heat source unit 2, a user-side device such as a hot water tank 51, and a user-side heat exchanger 52 that performs heat exchange between the liquid (hot water) in the hot water tank 51 and the heat medium after heat exchange in the first heat exchanger 13.

[0023] The heat medium circuit is a closed circuit. The heat medium circuit includes a circulation pump 53 for circulating the heat medium, a constant flow rate valve 55 for keeping the circulating flow rate of the heat medium constant, a check valve 56 for preventing backflow of the heat medium, a hot water tank 51, a flow meter 57, and a heat medium flow path 58 for circulating water as a heat medium by connecting the first heat exchanger 13. The heat medium is generally water, but antifreeze may be used to prevent freezing.

[0024] A user of the heat pump device 1 inputs a desired set temperature in the load unit 3 from the controller 26. The heat medium circulation type heating heat pump device 1 is used to constantly maintain liquid such as hot water in the hot water tank 51 to be used outside in the load unit 3 at a high temperature. For this reason, the set temperature of the heat medium set in the controller 26 is determined by the request of the hot water user. This set temperature is, for example, 40°C to 60°C, which is higher than the set temperature of an air conditioner intended for heating.

[0025] The circulation pump 53 circulates the heat medium between the first heat exchanger 13 and the user-side device 27 when in operation. The circulation pump 53, the constant flow valve 55, the check valve 56, and the flow meter 57 may be provided in the heat medium flow path 58 on the load unit 3 side, or may be provided in the heat medium flow path 58 on the heat source unit 2 side. If the refrigerant circulating through the refrigerant pipe 17 is at a higher temperature than the heat medium circulating through the heat medium flow path 58, the heat medium is heated in the first heat exchanger 13, heats the water in the hot water tank 51 in the user-side heat exchanger 52 (radiator), radiates heat, and is returned to the first heat exchanger 13.

[0026] The heat medium flow path 58 includes pipe joints 59, 59. These pipe joints 59, 59 connect the heat source unit 2 and the load unit 3 in a detachable manner.

[0027] In order to control the temperature of the heat medium, the heat source unit 2 is provided with a heat medium inlet temperature sensor 71 provided on the inlet side of the first heat exchanger 13 to detect a temperature TWI of the heat medium flowing into the first heat exchanger 13, and a heat medium outlet temperature sensor 72 provided on the outlet side of the first heat exchanger 13 to detect a temperature TWO of the heat medium flowing out from the first heat exchanger 13. The temperature TWI is the temperature of the heat medium (return water temperature) before heat exchange with the refrigerant of the refrigeration cycle 5 in the first heat exchanger 13, and the temperature TWO is the temperature of the heat medium after heat exchange with the refrigerant of the refrigeration cycle 5 in the first heat exchanger 13.

[0028] The load unit 3 may include a flowmeter 57 that detects the flow rate of the heat medium circulating through the heat medium flow path 58. The circulating flow rate of the heat medium may be detected by the flowmeter 57, or may be a flow rate that is stored in advance corresponding to the rotation speed of the circulating pump 53, may be a flow rate that is set by manual input, or may be a correction value that is corrected when a change occurs during operation at an estimated flow rate.

[0029] The control unit 29 includes hardware resources such as a processor, a memory, and peripheral circuits thereof, etc. The control unit 29 is configured as a computer in which the processor executes various programs to realize information processing by software using the hardware resources.

[0030] Furthermore, the control unit 29 controls the operation of the heat source unit 2 and the operation of the load unit 3 based on an input operation to the controller 26. That is, the control unit 29 controls the operations of the compressor 11, the inverter device 25, the four-way valve 12, the expansion valve 15, and the blower fan 21 based on an input operation by the user via the controller 26.

[0031] Furthermore, the control unit 29 controls the operation stop and rotation speed of the compressor 11, the direction of the four-way valve 12, the opening degree of the expansion valve 15, and the operation stop and rotation speed of the blower fan 21 based on one or more of the temperature detection values ​​of each part by the suction temperature sensor 41, the discharge temperature sensor 42, the refrigerant outlet side temperature sensor 43, the refrigerant temperature sensor 45, the outside air temperature sensor 46, the heat medium inlet temperature sensor 71, and the heat medium outlet temperature sensor 72, and the circulation flow rate of the heat medium detected or calculated. For example, the rotation speed of the compressor 11, i.e., the output frequency of the inverter device 25, is determined according to the difference between the detected temperature of the heat medium outlet temperature sensor 72 and the set temperature of the heat medium set by the controller 26. In addition, the condensation temperature, which is the detected temperature of the refrigerant outlet side temperature sensor 43, is used to prevent the refrigeration cycle components such as the first heat exchanger from becoming abnormally high pressure. That is, when the condensation temperature, which is the detected temperature of the refrigerant outlet side temperature sensor 43, exceeds a predetermined value, for example, 65°C, the rotation speed of the compressor 11 is reduced.

[0032] In addition, in order to remove frost formed in the second heat exchanger 16 during the operation of heating the heat medium in the first heat exchanger 13, the refrigeration cycle 5 performs a defrosting operation by switching the flow direction of the refrigerant flowing through the refrigerant pipe 17 by the four-way valve 12. When performing the defrosting operation, the heat pump device 1 reverses the four-way valve 12 to generate a refrigerant flow in the refrigeration cycle 5 in a direction opposite to the refrigerant flow that heats the heat medium. That is, the refrigeration cycle 5 causes the refrigerant to flow through the compressor 11, the four-way valve 12, the second heat exchanger 16, the expansion valve 15, the first heat exchanger 13, the four-way valve 12, and the compressor 11 in this order. During this defrosting operation, the second heat exchanger 16 functions as a condenser, and the first heat exchanger 13 functions as an evaporator. The second heat exchanger 16, which functions as a condenser, melts the frost attached to its surface.

[0033] In addition, for warm regions where defrosting operation is not required, the refrigeration cycle 5 may be dedicated to heating water without the four-way valve 12. In this case, the discharge side of the compressor 11 is connected to the first heat exchanger 13 via the refrigerant piping 17, and the suction side of the compressor 11 is connected to the second heat exchanger 16 via the refrigerant piping 17.

[0034] FIG. 2 is a TH diagram when the operation of the refrigeration cycle 5 of the heat medium circulation type heating heat pump device according to the embodiment of the present invention is stable.

[0035] As shown in FIG. 2, in the refrigeration cycle 5 of the heat pump device 1 according to this embodiment, when a heat medium is to be heated, the refrigerant is compressed from point A to point B by the compressor 11, the heat medium is heated in the first heat exchanger 13 acting as a condenser and the refrigerant is caused to release heat from point B to point C, the refrigerant is adiabatically expanded from point C to point D by the expansion valve 15, and the refrigerant is caused to absorb heat from point D to point A by the second heat exchanger 16 acting as an evaporator.

[0036] During this process, the suction temperature sensor 41 of the heat source unit 2 detects the refrigerant temperature TS at point A, the discharge temperature sensor 42 detects the refrigerant temperature TD at point B, the refrigerant outlet temperature sensor 43 detects the refrigerant temperature TC at point C, and the refrigerant temperature sensor 45 detects the refrigerant temperature TE at point D.

[0037] The temperature TD at point B is the temperature of the refrigerant immediately after it is discharged from the compressor 11. The temperature (vertical axis) and enthalpy (horizontal axis) at point B are both the highest in the refrigeration cycle 5. The temperature TC at point C is the temperature of the refrigerant after it has passed through the first heat exchanger 13 (that is, a condenser and a water heat exchanger). Due to heat transfer from the refrigerant circulating through the refrigeration cycle 5 to the heat medium circulating through the load unit 3, the temperature and enthalpy of point C are lower than those of point B. In other words, when the operation of the refrigeration cycle 5 is stable, the relationship (temperature TD)>(temperature TC) holds.

[0038] Here, when the discharge temperature sensor 42 falls off, the temperature TD detected by the discharge temperature sensor 42 moves to point A'. The temperature of point A', that is, the temperature TD detected by the fallen discharge temperature sensor 42, is not the actual temperature of the refrigerant discharged from the compressor 11, but substantially corresponds to the outside air temperature. In general, the outside air temperature is lower than the temperature of the refrigerant immediately after it is discharged from the compressor 11. Therefore, when the operation of the refrigeration cycle 5 is stable, it is possible to determine that the discharge temperature sensor 42 has fallen off from the discharge pipe by detecting the relationship (temperature TD)<(temperature TC). Therefore, it is found that using the detected temperature TC of the refrigerant temperature sensor 43 is effective in inexpensively detecting the fall-off of the discharge temperature sensor 42 by using a temperature sensor already provided in the refrigeration cycle 5.

[0039] However, particularly in the case of the heat medium circulation type heating heat pump device 1, other than when the refrigeration cycle 5 is stable, for example, in a transitional period immediately after the start of the refrigeration cycle 5, simply detecting the relationship (temperature TD)<(temperature TC) may result in a false determination that the discharge temperature sensor 42 has fallen off, and this needs to be addressed.

[0040] In FIG. 3, the time on the horizontal axis is set to zero when the compressor starts operating, and an example of temperature transition from immediately before the start of the heat medium circulation type heat pump apparatus according to the embodiment of the present invention to immediately before stable operation is shown.

[0041] As shown in Fig. 3, immediately after the start of the refrigeration cycle 5, the temperature TD of the refrigerant immediately after it is discharged from the compressor 11 may be lower than the temperature TC of the refrigerant after it has passed through the first heat exchanger 13 (solid line arrow area F in Fig. 3). In other words, whether the discharge temperature sensor 42 has fallen off or not, in the solid line arrow area F immediately after the start of the refrigeration cycle 5, the temperature relationship of (temperature TD) < (temperature TC) appears. Such a temperature relationship is a problem specific to the heat medium circulation type heating heat pump device 1, in which, under a situation in which the temperature of the heat medium circulating in the load unit 3 is higher than the temperature of the refrigerant circulating in the refrigeration cycle 5, heat is transferred from the heat medium circulating in the load unit 3 in the first heat exchanger 13 to the refrigerant that starts circulating in the refrigeration cycle 5 by the start of the compressor 11, and the refrigerant is warmed by the heat medium.

[0042] Therefore, if the relationship (temperature TD)<(temperature TC) is simply detected in the solid arrow region F immediately after the start of the refrigeration cycle 5, it may be erroneously determined that the discharge temperature sensor 42 has fallen off.

[0043] Therefore, the control unit 29 of the heat pump device 1 according to this embodiment determines whether or not the discharge temperature sensor 42 has fallen off from the piping on the discharge side of the compressor 11 after a predetermined standby time has elapsed since the compressor 11 was started. This allows the control unit 29 to more accurately determine whether or not the discharge temperature sensor 42 has fallen off.

[0044] FIG. 4 is a graph showing another example of temperature transition from immediately before the start of the heat medium circulation type heating heat pump apparatus according to the embodiment of the present invention to immediately before stable operation, with the time on the horizontal axis being set to zero when the compressor starts operating, as in FIG.

[0045] The heat pump device 1 of the example shown in Fig. 4 has a wider operating temperature range, i.e., a wider range of outside air temperatures in the environment in which the heat pump device 1 is installed, than the heat pump device 1 of the example shown in Fig. 3. Note that the heat pump device 1 of the example shown in Fig. 4 has a wider range of outside air temperatures in the environment in which the heat pump device 1 is installed on the low temperature side. In Fig. 4, for reference, an example of the detected temperature of the discharge temperature sensor 42 when the discharge temperature sensor 42 falls off the discharge pipe is shown by a dashed dotted line G.

[0046] As in the example of Figure 3, in the solid arrow region F immediately after the start of the refrigeration cycle 5, the temperature TD of the refrigerant immediately after being discharged from the compressor 11 is lower than the temperature TC of the refrigerant after passing through the first heat exchanger 13.

[0047] In addition to the problem of erroneous judgment specific to the above-mentioned heat medium circulation type heating heat pump device, as shown in Fig. 4, it can be seen that the duration of the temperature relationship (temperature TD) < (temperature TC) immediately after the start of the refrigeration cycle 5 varies depending on the environment in which the heat pump device 1 is installed. In the example of Fig. 4, in which the outside air temperature of the usage environment is wider toward the low temperature side compared to the example of Fig. 3, the area F indicated by the solid arrow is expanded, that is, the duration of the temperature relationship (temperature TD) < (temperature TC) is prolonged.

[0048] Therefore, regardless of the operating temperature range of the heat pump device 1 (temperature conditions of the installation environment) or the capacity of the refrigeration cycle 5, if a "predetermined standby time" is set after the compressor 11 is started, there is a risk that the relationship (temperature TD) < (temperature TC) will be detected after the standby time has elapsed, and the discharge temperature sensor 42 will be erroneously determined to have fallen off, regardless of whether the discharge temperature sensor 42 has fallen off or not.

[0049] Therefore, the control unit 29 of the heat pump device 1 according to this embodiment determines whether or not the discharge temperature sensor 42 has fallen off from the piping on the discharge side of the compressor 11 based on the difference between the discharge temperature TD and the temperature TC of the refrigerant after heat exchange, after a predetermined standby time has elapsed since the compressor 11 was started. This allows the control unit 29 to accurately and quickly determine whether or not the discharge temperature sensor 42 has fallen off, regardless of the operating temperature range (temperature conditions of the installation environment) or the capacity of the refrigeration cycle 5.

[0050] The control using the discharge temperature sensor executed by the heat medium circulation type heat pump device according to the embodiment of the present invention will be described with reference to the flowchart of Fig. 5. In the following description, each step S* in the flow chart will be represented by S*.

[0051] The control unit 29 of the heat pump device 1 according to this embodiment starts control based on the discharge temperature sensor. First, the control unit 29 starts the compressor 11 and starts measuring the operation time of the compressor 11 at the same time. Next, in order to protect against abnormal high pressure, it is determined whether the detection temperature TD of the discharge temperature sensor 42 exceeds a judgment value set for detecting high pressure abnormality, for example, 125°C (S0). If the detection temperature TD exceeds the judgment value (YES in S0), the control unit 29 determines that the compressor 11 has reached a high pressure abnormality, and executes control to protect the compressor 11 (S8). This protection control is, for example, various controls to reduce the load on the compressor, including control to reduce the frequency of the output of the inverter device 25 to be driven, control to open the opening degree of the expansion valve 15, or control to stop the compressor 11.

[0052] If the detected temperature TD does not exceed the judgment value (NO in S0), the compressor continues to operate, and the process proceeds to S1 and subsequent steps for determining whether the discharge temperature sensor has fallen off. Note that high pressure abnormalities in the compressor 11 are often caused by a temporary increase in load due to the surrounding environment. Therefore, if the load is reduced, the compressor 11 can continue to operate. Also, if the compressor 11 is stopped and then restarted, the surrounding environment may change and the compressor may be able to continue operating without reaching abnormally high pressure, so there is no need to immediately prohibit operation.

[0053] The control unit 29 judges whether a predetermined standby time has elapsed since the compressor 11 was started (S1). If the judgment in S1 is negative, that is, if the predetermined standby time has not elapsed since the compressor 11 was started (No in S1), the control unit 29 initializes (sets to zero) the time measurement of the dropout determination timer (S2), ends the dropout determination control of the discharge temperature sensor, and returns to the start. The dropout determination timer is a separate timer from the timer that measures the operating time of the compressor 11.

[0054] If the determination in S1 is positive, that is, if a predetermined standby time has elapsed since the compressor 11 was started (Yes in S1), the control unit 29 determines whether or not the difference obtained by subtracting the temperature TC of the refrigerant after heat exchange from the discharge temperature TD (discharge temperature TD) - (temperature TC of the refrigerant after heat exchange) is smaller than a predetermined temperature value (S3). Note that the method of determining the predetermined temperature value in this step will be described later.

[0055] If the judgment in S3 is negative, that is, if (discharge temperature TD) - (refrigerant temperature after heat exchange TC) ≧ (predetermined temperature value) (No in S3), the timing of the drop-out determination timer is initialized (set to zero) (S2) and the process returns to the beginning (S0).

[0056] If the determination in S3 is positive, that is, if (discharge temperature TD) - (refrigerant temperature after heat exchange TC) < (predetermined temperature value) (Yes in S3), the control unit 29 determines whether the drop-out determination timer is equal to or longer than a predetermined erroneous detection prevention time (S4). The erroneous detection prevention time is set to prevent and avoid erroneous determination when instantaneous noise occurs in the output of sensors including the discharge temperature sensor 42. The erroneous detection prevention time is set to, for example, 10 seconds.

[0057] If the judgment in S4 is negative, that is, if the elapsed time on the drop-off determination timer is shorter than the predetermined erroneous detection prevention time (No in S4), the control unit 29 starts or continues timing on the drop-off determination timer (S5) and returns to the beginning.

[0058] If the determination in S4 is positive, that is, if the time elapsed on the dropout determination timer is equal to or greater than the predetermined erroneous detection prevention time (Yes in S4), the control unit 29 determines that the discharge temperature sensor 42 has fallen off (S6), that is, determines that a state in which normal detection of the discharge temperature TD is impossible, and stops the compressor 11 to protect the refrigeration cycle equipment, stops the heat pump device 1, and further displays an abnormality that the discharge temperature sensor 42 has fallen off on the display unit 28, and ends the control for determining whether the discharge temperature sensor has fallen off (S7). After S7, operation of the heat pump device 1 is prohibited until a serviceman completes repairing the dropout of the discharge temperature sensor 42 and resets the heat pump device 1.

[0059] If the compressor 11 is operated with the outside air temperature at 2 degrees Celsius and the discharge temperature sensor 42 removed, there is a risk that the pressure Pd of the refrigerant discharged from the compressor 11 will deviate from the operating range of the compressor 11 approximately 1200 seconds (20 minutes) after the compressor 11 is started (the point of the maximum allowable pressure Pmax in FIG. 3). The pressure Pmax corresponds to approximately 125°C when converted into the discharge temperature TD. If the outside air temperature becomes higher than 2 degrees Celsius, the pressure Pd of the refrigerant discharged from the compressor 11 will become even higher. This will shorten the time required for the pressure Pd of the refrigerant discharged from the compressor 11 to deviate from the operating range of the compressor 11.

[0060] Furthermore, the duration of temperature TD<temperature TC is longer when the compressor 11 is started when the outside air temperature is -10 degrees Celsius than when the compressor 11 is started when the outside air temperature is 2 degrees Celsius (FIGS. 3 and 4). That is, the duration of temperature TD<temperature TC, in other words, the period during which a temperature relationship that may lead to an erroneous determination that the discharge temperature sensor 42 has fallen off after the compressor 11 is started, becomes apparent, the lower the outside air temperature is, the longer it becomes.

[0061] Therefore, while it is preferable that the specified waiting time in step S1 is shorter than 1200 seconds from the start of the compressor 11, if the specified waiting time is set to an extremely short time, there is a risk that the discharge temperature sensor 42 will be erroneously detected as falling off based on the temperature relationship of (temperature TD) < (temperature TC).

[0062] Furthermore, when the compressor 11 is started up when the outside air temperature is minus 10 degrees Celsius, the temperature difference between (temperature TD) and (temperature TC) is approximately minus 20 degrees (FIG. 4). Furthermore, the determination of the dropout of the discharge temperature sensor 42 can be confirmed earlier by detecting (temperature TD) - (temperature TC) < (judgment margin M) rather than by simply detecting the magnitude relationship between (temperature TD) and (temperature TC). In other words, the "judgment margin M" in (temperature TD) - (temperature TC) < (judgment margin M) has the effect of shortening the period of erroneous judgment of the dropout of the discharge temperature sensor 42 immediately after the start of the compressor 11 (solid line arrow α in FIG. 4). This "judgment margin M" corresponds to the temperature difference between (temperature TD) and (temperature TC) in S3 of the control flow chart in FIG. 5.

[0063] Therefore, the predetermined waiting time in S1 is set to 600 seconds (10 minutes), which is half of the above 1200 seconds, assuming that the high pressure rise speed is fast. At the time of 600 seconds, it is necessary to set the predetermined temperature value in S3, that is, the judgment margin M, so that the discharge temperature sensor dropout detection can be performed reliably, in other words, so as to prevent erroneous detection. Therefore, under the condition that the outside air temperature is the lowest in the operable range and the water temperature in the hot water tank 51 is high, that is, under the condition that the set temperature set by the controller 26 is set to the highest value, a value slightly higher than the temperature difference (temperature TD)-(temperature TC) at the time 600 seconds after the compressor 11 starts operating is set as the predetermined temperature value. Based on this idea, the inventors have found that in the heat medium circulation type heating heat pump device 1 that can operate even at low outside air temperatures, the predetermined waiting time in S1 can be shortened and erroneous judgment of the discharge temperature sensor 42 dropout can be avoided by setting the judgment margin M to minus 10 degrees. Here, in the heat medium circulation type heating heat pump device 1, the predetermined temperature value, i.e., the judgment margin M, needs to be a negative value. By setting it in this way, the predetermined waiting time can be shortened and erroneous judgment of the detachment of the discharge temperature sensor 42 can be avoided.

[0064] In other words, the specified waiting time in S1 and the specified temperature value in S3 vary depending on the capacity of the refrigeration cycle 5 and the specifications required for the load unit 3, but the inventors have confirmed that by setting the specified waiting time to 600 seconds and the specified temperature value in S3 to minus 10 degrees, it is possible to accommodate a wide range of capacities of the refrigeration cycle 5 and specifications required for the load unit 3.

[0065] The notification in S7 and S8 is not limited to notifying an error by light on the display unit 28, but may be by sound, such as a speaker. In other words, it is sufficient for the control unit 29 to be provided with an alarm that notifies an error by at least one of sound and light.

[0066] Furthermore, when the control unit 29 determines that the discharge temperature sensor 42 has fallen off the piping on the discharge side of the compressor 11 (S6), it prohibits restarting the compressor 11 until a serviceman repairs it, attaches the discharge temperature sensor 42, and resets the control unit 29. On the other hand, in S0, after the detected temperature TD of the discharge temperature sensor 42 exceeds the judgment value and the compressor 11 is stopped, the compressor 11 may be automatically restarted after a predetermined time. After that, if a high pressure abnormality is detected repeatedly multiple times in a short period of time, for example, three or more times in two hours, it may be possible to prohibit further restarting of the compressor 11 and to issue an abnormality alert.

[0067] As described above, the heat medium circulation type heating heat pump device 1 according to this embodiment judges that the discharge temperature sensor 42 has fallen off from the piping on the discharge side of the compressor 11 and stops the compressor 11 when the difference obtained by subtracting the refrigerant temperature TC after the heat exchange from the discharge temperature TD is smaller than a predetermined temperature value after a predetermined standby time has elapsed since the compressor 11 was started. Therefore, the heat medium circulation type heating heat pump device 1 can widely accommodate both the capacity of the refrigeration cycle 5 and the specifications required for the load unit 3, and can reliably determine whether the discharge temperature sensor 42 has fallen off at an early stage. In addition, the heat pump device 1 reliably determines that the discharge temperature sensor 42 has fallen off at an early stage before the pressure reaches an abnormal high pressure and stops the compressor 11, thereby reliably preventing the refrigerant pressure Pd from deviating from the operating range of the compressor 11 without providing a pressure sensor.

[0068] Furthermore, when the heat medium circulation type heating heat pump device 1 according to this embodiment determines that the discharge temperature sensor 42 has fallen off from the piping on the discharge side of the compressor 11, it notifies the user of the error by at least one of sound and light. Therefore, the heat pump device 1 can quickly and reliably determine that the discharge temperature sensor 42 has fallen off, and can easily let the user know that the discharge temperature sensor 42 has fallen off.

[0069] Furthermore, when the heat pump device 1 according to this embodiment determines that the discharge temperature sensor 42 has fallen off from the piping on the discharge side of the compressor 11, it prohibits restarting of the compressor 11. Therefore, the heat pump device 1 can quickly and reliably determine that the discharge temperature sensor 42 has fallen off, and can reliably prevent the refrigerant pressure Pd from deviating from the operating range of the compressor 11 due to operation of the compressor 11 with the discharge temperature sensor 42 falling off.

[0070] Therefore, the heat pump device 1 according to this embodiment can more reliably detect the detachment of the discharge temperature sensor 42 that detects the discharge temperature TD of the compressor 11 by using an existing temperature sensor in the heat medium circulation type heating heat pump device 1.

[0071] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0072] 1...heat medium circulation type heating heat pump device, 2...heat source unit, 3...load unit, 5...refrigeration cycle, 11...compressor, 13...first heat exchanger, 15...expansion valve, 16...second heat exchanger, 17...refrigerant piping, 21...blower fan, 25...inverter device, 26...controller, 27...usage side equipment, 28...display unit, 29...control unit, 41...suction temperature sensor, 42...discharge temperature sensor, 43...refrigerant outlet side temperature sensor, 45...refrigerant temperature sensor, 52...usage side heat exchanger.

Claims

1. a refrigeration cycle including a compressor, a first heat exchanger, a throttling device, and a second heat exchanger, in which a refrigerant discharged from the compressor is circulated through a refrigerant pipe in this order through the first heat exchanger, the throttling device, and the second heat exchanger; A user device; a medium flow path that connects the first heat exchanger of the refrigeration cycle to the utilization side device and circulates a heat medium heated by heat exchange with the refrigerant in the first heat exchanger through the utilization side device; a discharge temperature sensor provided in the refrigerant pipe on the discharge side of the compressor to detect a discharge temperature of the compressor; a first heat exchanger outlet side temperature sensor that detects a temperature of the refrigerant after heat exchange flowing out of the first heat exchanger; and a control unit that stops the compressor when a difference obtained by subtracting the refrigerant temperature after the heat exchange from the discharge temperature is smaller than a predetermined temperature value after a predetermined standby time has elapsed since the compressor is started.

2. 2. The heat medium circulation type heating heat pump device according to claim 1, further comprising an alarm that notifies an error by at least one of sound and light when a difference obtained by subtracting the refrigerant temperature after the heat exchange from the discharge temperature is smaller than a predetermined temperature value after a predetermined standby time has elapsed since the compressor is started.

3. The heat medium circulation type heating heat pump apparatus according to claim 1 or 2, wherein after the compressor is stopped, restart of the compressor is prohibited.

4. The heat medium circulation type heat pump device according to claim 1 , wherein the control unit stops the compressor when the discharge temperature detected by the discharge temperature sensor is equal to or higher than a predetermined value.

5. The compressor further includes an inverter device for variably driving the compressor, The heat medium circulation type heating heat pump device according to claim 1 , wherein the control unit reduces an output frequency of the inverter device when the discharge temperature detected by the discharge temperature sensor is equal to or higher than a predetermined value.

6. The heat medium circulation type heat pump apparatus according to claim 1 , wherein the predetermined temperature value is a negative value.

Images