JP2023157663A - heat source unit - Google Patents

Abstract

To detect a state that there is no flow in a used fluid in a heat exchanger.SOLUTION: A heat source unit according to an embodiment includes: a compressor which compresses a refrigerant; a heater which heats the compressor; a first heat exchanger which conducts heat exchange between the refrigerant and a used fluid; a first temperature sensor installed at the first heat exchanger; a second temperature sensor installed at a portion of the first heat exchanger where a heat quantity received through heat radiation from the heater is different from that of the first temperature sensor; and a controller which prohibits actuation of the compressor based on a difference between detection temperatures of the first and second temperature sensors.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to a heat source unit.

A heat pump type heat source unit is known in which a compressor, an evaporator, an expansion valve, and a condenser are connected through refrigerant piping, and the refrigerant is circulated between these devices. The condenser constitutes the heat dissipation part of the heat source unit, and the evaporator, which is the cooling part, absorbs heat from air or other fluid. Here, the condenser exchanges heat between the refrigerant and the utilized fluid (for example, water), and releases the heat absorbed by the evaporator to the utilized fluid. The heated utilization fluid (eg, hot water) is supplied to an external device to be heated. Both the condenser and the evaporator are generally configured as heat exchangers. There are also heat source units that can perform both heating and cooling by reversing the refrigeration cycle, allowing the evaporator and condenser to be interchanged to cool the fluid to be used and supply cold water to an external device.

In such a heat source unit, a pump is installed on the external device side, and the pump is driven to circulate or circulate the utilized fluid between the external device and the heat source unit. External devices can be used in various ways, such as heat exchangers for heat radiation or heat absorption for cooling and heating indoor rooms, and hot water tanks.

Here, there is a technique in which a pump interlock mechanism is installed in the heat source unit to prohibit the operation of the compressor under the condition that the pump that circulates or distributes the fluid to be used in the external device is stopped. This prevents the evaporator from freezing or placing an excessive load on the entire heat source unit (Patent Document 1).

Japanese Patent Application Publication No. 10-078266

However, even when the pump is stopped, if a short circuit occurs in the terminals of the pump interlock mechanism for some reason, the prohibition of operation may be unintentionally canceled. Further, due to a failure of the pump itself, the pump may be stopped even when the pump is energized. Furthermore, in the piping that circulates the fluid used between the heat source unit and external equipment, scale may gradually accumulate inside the pipe over the course of long-term use, resulting in clogging of the piping. In this case, the pump Even if the pump is operated, the fluid does not flow, and even if a signal indicating that the pump is operating is received at the terminal of the pump interlock mechanism, the fluid may not actually flow. In order to avoid this situation, if you try to directly detect the flow rate of the fluid flowing through the piping between the heat source unit and the external device, you will need to add special parts such as a flow rate sensor, which will increase the number of parts. I end up.

Therefore, an object of the present invention is to provide a heat source unit that does not rely on a so-called pump interlock mechanism, suppresses an increase in the number of parts, and can accurately detect that the fluid to be used is not flowing. do.

A heat source unit according to an embodiment of the present invention includes a compressor that compresses a refrigerant, a heater that heats the compressor, a first heat exchanger that exchanges heat between the refrigerant and a fluid to be used, and a first heat exchanger that performs heat exchange between the refrigerant and the fluid to be used. a first temperature sensor installed in the first heat exchanger, a second temperature sensor installed at a location where the amount of heat received by heat radiation from the heater is different from that of the first temperature sensor, and the first and second temperature sensors. A controller that prohibits starting of the compressor based on a difference in temperature detected by the sensor.

FIG. 1 is a schematic diagram showing the overall configuration of a heat source unit according to an embodiment of the present invention. It is a schematic diagram which shows the electrical connection relationship of the compressor and its peripheral equipment in a heat source unit same as the above. FIG. 3 is a plan view showing the positional relationship of internal devices when the casing of the heat source unit is viewed from above. It is an elevational view showing the positional relationship of internal devices when the housing of the heat source unit same as the above is viewed from the side. 3 is a flowchart showing the contents of a basic control routine of a heat source unit. It is a flowchart which shows the content of compressor start-up control in the routine same as the above. It is a graph showing changes in the inlet liquid temperature Twi, the outlet liquid temperature Two, and the temperature difference ΔTw when the power supply to the heater is cut off in a state where there is no flow of the fluid to be used. It is a graph showing changes in the inlet liquid temperature Twi, the outlet liquid temperature Two, and the temperature difference ΔTw when a state in which there is no flow of the fluid to be used is maintained after energization of the heater is started. It is a graph showing changes in the inlet liquid temperature Twi, the outlet liquid temperature Two, the temperature difference ΔTw, and the flow rate Rcw of the utilized fluid when water flow is started from a state where there is no flow of the utilized fluid.

Embodiments of the present invention will be described below with reference to the drawings.

The configuration of the heat source unit (hereinafter simply referred to as "heat source unit") U shown in FIG. 1 will be described with reference to FIGS. 2 to 4 as appropriate.

In this embodiment, the heat source unit U constitutes a heat pump type refrigeration cycle device, and cools or heats the utilized fluid that is circulated between a cooling/heating device or a hot water storage device (not shown) configured as an external device. Is possible. Although water is generally used as the fluid to be used, brine can also be used for purposes such as anti-freezing. The refrigerant is, for example, R410A, R32 refrigerant or a CO ₂ refrigerant containing carbon dioxide (CO ₂ ). In this embodiment, water is used as the fluid to be used. In FIG. 1, solid arrows indicate the flow of refrigerant during the generation of cold water, which supplies the fluid to be used after cooling, that is, cold water, to an external device. Dotted arrows indicate the flow of refrigerant during generation of hot water to supply hot water.

The heat source unit U includes a compressor 1, a first heat exchanger 2, a second heat exchanger 3, a four-way valve 4, and an expansion valve 5 as main components, and fluidly connects these components. , a refrigerant pipe 6 is provided for circulating refrigerant between these components. These compressor 1, first heat exchanger 2, second heat exchanger 3, four-way valve 4, expansion valve 5, and refrigerant pipe 6 are housed inside the casing C. The casing C is installed outdoors, and as shown in FIGS. 3 and 4, it consists of a high-strength metal case made of a box-shaped sheet metal or the like, and has a part on the side for ventilation to the second heat exchanger 3. An opening is provided.

The compressor 1 is, for example, an internal high-pressure hermetic rotary compressor that compresses refrigerant, raises the pressure, and discharges the compressor. The compressor 1 includes a closed pressure-resistant container made of iron as its outer shell, and a rotary compression mechanism is housed inside the container. Lubricating oil for lubricating the compression mechanism is stored in the lower part of this closed container. The operating frequency of the compressor 1 can be changed by known inverter control. However, the operating frequency does not necessarily need to be changeable, and the compressor 1 may be operated at a constant speed using a commercial frequency.

A heater 7 is arranged around the outer periphery of the compressor 1 so as to be able to heat the compressor 1, specifically, to be able to transfer heat to the inside of the compressor 1. For example, a belt heater or a cord heater can be applied to the heater 7. The compressor 1 can be heated and kept warm by wrapping the belt heater 7 around the outer periphery of the compressor 1 and arranging an appropriate heat insulating material around it. The heat generated by the heater 7 is transmitted to the inside of the compressor 1, and heats the lubricating oil that is stored inside and lubricates the compression mechanism inside the compressor 1, thereby reducing its viscosity even when the compressor 1 is stopped. properly maintain it.

The first heat exchanger 2 exchanges heat between the refrigerant and the fluid to be used. The first heat exchanger 2 is, for example, a coil-type water-refrigerant heat exchanger, in which a pipe 2a through which the refrigerant flows and a pipe (hereinafter referred to as "water pipe") 2b through which the fluid to be used flows are each formed in a coil shape, It has a structure in which these tubes 2a and 2b are joined or welded together. Note that the first heat exchanger 2 is not limited to a coil type heat exchanger, and may also be a plate type heat exchanger in which a plurality of thin plates are stacked and the refrigerant and the fluid to be used alternately flow in the gaps between adjacent plates. May be used. For the sake of explanation, FIG. 1 simplifies the piping structure, and shows the pipes 2a through which the refrigerant inside the first heat exchanger 2 flows and the water pipes 2b through which the utilization fluid flows, respectively, by thick dotted lines.

Here, as shown in FIGS. 3 and 4, the housing C that houses the components of the heat source unit U is provided with piping joints j1 and j2 at the inlet and outlet of the fluid to be used, respectively, on the back side thereof. It is being The fluid to be used is introduced into the heat source unit U from the inlet side piping p1 extending from an external device via the inlet piping joint j1, and flows into the water pipe 2b inside the first heat exchanger 2. The utilized fluid after heat exchange with the refrigerant exits the water pipe 2b and is discharged from the first heat exchanger 2, that is, the heat source unit U, via the outlet pipe joint j2. The utilization fluid that has exited the heat source unit U is supplied to an external device via the outlet side piping p2. FIG. 1 shows the flow of the utilized fluid by thick arrows.

The second heat exchanger 3 performs heat exchange between the refrigerant and air, for example, outside air. The second heat exchanger 3 is, for example, a fin-and-tube type air refrigerant heat exchanger, and includes a tube 31 made of a copper pipe and a plurality of fins 32 made of a thin aluminum plate (FIG. 3). The second heat exchanger 3 further includes a fan F and a motor M serving as a drive source thereof, and the fan F forcibly forms a flow of air (outside air) along the surface of the fins 32 so that the tubes 31 Promotes the exchange of heat between the refrigerant flowing inside and the air.

As shown in FIG. 3, the inside of the casing C is divided into a blower room A and a machine room B on the left and right sides by a partition plate 9 that extends in the vertical direction. The fan F and the second heat exchanger 3 are housed in the blower room A, and the side surface of the casing C facing the second heat exchanger 3 is provided with an opening for ventilation. On the other hand, the machine room B houses refrigeration cycle devices other than the fan F and the second heat exchanger 3, specifically, the compressor 1, the first heat exchanger 2, the four-way valve 4, and the like. The partition plate 9 is formed of sheet metal or the like, and is attached to the casing C so that rainwater or the like that has entered the blower room A through the opening or the like does not enter the machine room B. Furthermore, the outer shell including the partition plate 9 and the top plate 10 (FIG. 4) of the casing C prevents rainwater or the like from directly entering the machine room B from the outside. The compressor 1 and the first heat exchanger 2 are arranged close to each other inside the machine room B.

The four-way valve 4 switches the flow path of the refrigerant discharged by the compressor 1 between when cold water is generated and when hot water is generated. When cold water is generated, the four-way valve 4 sets the flow path of the refrigerant in the direction from the four-way valve 4 toward the second heat exchanger 3 . Thereby, the refrigerant that has exited the four-way valve 4 passes through the second heat exchanger 3 and then flows into the first heat exchanger 2. On the other hand, when generating hot water, the refrigerant flow path is switched from the four-way valve 4 to the first heat exchanger 2. Thereby, the refrigerant that has exited the four-way valve 4 passes through the first heat exchanger 2 and then flows into the second heat exchanger 3.

The expansion valve 5 adjusts the pressure of the refrigerant exiting the condenser (for example, the second heat exchanger 3 that functions as a condenser when generating cold water) by the action of an orifice, and reduces the pressure drop due to flow resistance. This adjusts the pressure of the refrigerant heading toward the evaporator (for example, the first heat exchanger 2 that functions as an evaporator when generating cold water). As the expansion valve 5, for example, a stepping motor-driven electronic expansion valve can be used.

The refrigerant pipe 6 connects the compressor 1, the first heat exchanger 2, the second heat exchanger 3, the four-way valve 4, and the expansion valve 5 so that the refrigerant can flow therebetween. In this embodiment, the refrigerant pipe 6 can be roughly divided into a first refrigerant pipe 6a connected to the compressor 1 and the four-way valve 4, and a second refrigerant pipe 6a connected to the four-way valve 4 and the second heat exchanger 3. pipe 6b, a third refrigerant pipe 6c connected to the second heat exchanger 3 and the expansion valve 5, a fourth refrigerant pipe 6d connected to the expansion valve 5 and the first heat exchanger 2, a first heat exchanger 2 and the four-way valve 4, and a sixth refrigerant pipe 6f connected to the four-way valve 4 and the compressor 1.

When cold water is generated, the four-way valve 4 connects the inlet 4a and the first outlet 4b, and also connects the second outlet 4c and the outlet 4d. Switching of the flow paths in the four-way valve 4 is performed by controlling a pilot valve (not shown). When cold water is generated, the second heat exchanger 3 located upstream with respect to the flow of refrigerant operates as a condenser or a heat radiator, and the first heat exchanger 2 located downstream acts as an evaporator or heat absorber. operate as a division. The refrigerant discharged from the compressor 1 heads to the second heat exchanger 3 via the four-way valve 4, receives the action of the expansion valve 5, passes through the first heat exchanger 2, and then passes through the four-way valve 4. It returns to the compressor 1 via.

On the other hand, when generating hot water, the four-way valve 4 switches the connection destination of the inflow port 4a to the second outflow port 4c and switches the connection destination of the outflow port 4d to the first outflow port 4b under the control of the pilot valve. . When generating hot water, the first heat exchanger 2 located upstream with respect to the flow of refrigerant operates as a condenser or a heat radiator, and the second heat exchanger 3 located downstream acts as an evaporator or heat absorber. operate as a division. The refrigerant discharged from the compressor 1 heads to the first heat exchanger 2 via the four-way valve 4, receives the action of the expansion valve 5, passes through the second heat exchanger 3, and then passes through the four-way valve 4. It returns to the compressor 1 via.

In addition to the above, the heat source unit U includes a controller 101, an inlet temperature sensor 111, an outlet temperature sensor 112, an operation switch 113, and a display device 114 as components of a control system. This embodiment further includes a relay 115 for energizing the heater, which will be described later. The controller 101 includes a control circuit including an inverter circuit and a microcomputer, and may be placed in the machine room B, or, for example, by being supported by the partition plate 9, the controller 101 can be installed in a case spanning the machine room B and the blower room A. It may be placed in the upper part of the body C.

As shown in FIGS. 1 and 4, the inlet temperature sensor 111 detects the temperature Twi of the fluid flowing into the first heat exchanger 2, specifically, the water pipe 2b of the first heat exchanger 2. It is something. The inlet temperature sensor 111 is, for example, a thermistor, and is arranged at the inlet of the fluid to be used into the first heat exchanger 2 . In this embodiment, the inlet temperature sensor 111 is a first relay pipe that connects the first heat exchanger 2 and the inlet pipe joint 111, and more specifically, It is located close to 2.

The outlet temperature sensor 112 detects the temperature Two of the fluid flowing out from the first heat exchanger 2, specifically, the water pipe 2b of the first heat exchanger 2. Similar to the inlet temperature sensor 111, a thermistor can be used for the outlet temperature sensor 112, and is disposed at the outlet of the fluid to be used with respect to the first heat exchanger 2. In this embodiment, the outlet temperature sensor 112 is a second relay pipe that connects the first heat exchanger 2 and the outlet pipe joint 112, and more specifically, It is installed at a location close to 2 (Figure 3). The inlet temperature sensor 111 and the outlet temperature sensor 112 are arranged in the machine room B together with the first heat exchanger 2.

The operation switch 113 is a switch that instructs the heat source unit U to operate and stop. The operation switch 113 is, for example, a push button switch, and is operated by the user.

The display device 114 displays the operating state of the heat source unit U, and is installed on the outside of the casing C, so that the user can check the displayed content and operate the display device 114. In this embodiment, the display devices 114 are connected to the controller 101 so that they can communicate with each other. Further, the display device 114 includes an operation panel in addition to a display section, and the operation switch 113 is incorporated into the operation panel and formed integrally with the display device 114.

The controller 101 inputs the detection signals output from the inlet temperature sensor 111 and the outlet temperature sensor 112, and also inputs various operation signals from the operation switch 113 and the display device 114, and controls the compressor 1 and the belt heater 7. Control behavior.

Referring to the circuit diagram of FIG. 2, the compressor 1 is connected to a commercial AC power source 11 via a rectifier 12, a capacitor 13, and an inverter 14, and is configured such that the operating frequency, that is, the rotation speed can be changed by the inverter 14. has been done. Here, the heat source unit U is always supplied with power from the commercial AC power supply 11 unless an upstream breaker (not shown) is shut off, so the controller 101 and the display device 114 are operated from the power supply 11. When power is supplied, the control operation can be continued at all times regardless of whether or not the operation switch 113 is operated on or off.

The belt heater 7 is connected in parallel with a rectifier 12 to a power source 11, and a relay 115 is installed in a circuit that connects the belt heater 7 to the power source 11. The relay 115 operates in response to a command signal from the controller 101, and closes the circuit in response to an ON command from the controller 101 to energize and operate the belt heater 7, and opens the circuit in response to an OFF command from the controller 101. , the power supply to the belt heater 7 is cut off, and the heating operation of the belt heater 7 is stopped. The on/off control of the belt heater 7 will be explained in detail later with reference to the flowchart shown in FIG.

Furthermore, referring to FIGS. 3 and 4, the inlet temperature sensor 111 and the outlet temperature sensor 112 are arranged at different heights. Specifically, the outlet temperature sensor 112 is located above the inlet temperature sensor 111.

More specifically, the compressor 1 is placed on the back side of the first heat exchanger 2, and the inlet temperature sensor 111 is placed on the introduction side opening of the water passage 2b on the front side of the first heat exchanger 2. It is arranged at an adjacent inlet portion, and is arranged at a height close to the lowest part of the installation area of the belt heater 7 on the outer periphery of the compressor 1. On the other hand, the outlet temperature sensor 112 is disposed on the front side of the first heat exchanger 2 at the outlet adjacent to the discharge side opening of the water passage 2b, and is further located than the top of the installation area of the belt heater 7. placed in a high position. The installation area of the belt heater 7 refers to the range of the outer periphery of the compressor 1 surrounded by the belt heater 7, and FIG. 4 schematically shows this with a chain double-dashed line.

In this embodiment, the machine room B inside the housing C where the compressor 1 and the first heat exchanger 2 are arranged, and the blower room A where the second heat exchanger 3 and the fan F are arranged are separated by a partition plate. separated by 9. Here, the machine room B is airtight to some extent, and while the compressor 1 is operating, a part of the air generated by the fan F may be flowed into the machine room B to cool the inverter 14. , While the compressor 1 is stopped, that is, while the refrigeration cycle is stopped, the fan F is also stopped, so almost no outside air flows into the machine room B.

Thereby, the inlet temperature sensor 111 and the outlet temperature sensor 112, that is, the inlet part of the first heat exchanger 2 where the inlet temperature sensor 111 is arranged and the first heat exchanger 2 where the outlet temperature sensor 112 is arranged. There is a difference in the amount of heat received by convective heat transfer using the belt heater 7 as a heat source, and the amount of heat received by the outlet temperature sensor 112 is larger than the amount of heat received by the inlet temperature sensor 111. In FIG. 4, the difference in height between the inlet temperature sensor 111 and the outlet temperature sensor 112 is indicated by the symbol Δh.

Returning to FIG. 1, the controller 101 inputs various signals output from the inlet temperature sensor 111, the outlet temperature sensor 112, and the operation switch 113, and sends them to the compressor 1, belt heater 7, display device 114, and relay 115. A command signal is output to the target.

In this embodiment, the operation of the heat source unit U is avoided under conditions where there is no flow of the fluid to be used, especially when the pump provided in the external device is stopped, and specifically, the startup of the compressor 1 is prohibited. do. The method will be explained based on the flowcharts shown in FIGS. 5 and 6.

The controller 101 starts the control according to the routine shown in FIGS. 5 and 6 in accordance with the ON operation of the operation switch 113 by the user, and thereafter repeatedly executes the control according to the routine shown in FIGS. 5 and 6 until the operation switch 113 is turned OFF.

In S101, it is determined whether the operation switch 113 of the heat source unit U is in an on state, in other words, whether or not the operation switch 113 has been turned on. If it is in the on state, the process advances to S102; if it is not in the on state, that is, if it is in the off state, the process advances to S106, regardless of whether the compressor 1 is in operation or stopped. The compressor 1 is brought to a stopped state. Next, the process advances to S102, and after activating the belt heater 7, this routine is repeated. In this way, even while the heat source unit U is stopped, the belt heater 7 continues to be energized, so the compressor 1 is always maintained at an appropriate temperature. Thereby, when the operation switch 113 is turned on, the compressor 1 can be started immediately and the operation of the heat source unit U can be started.

In S102, the temperature of the used fluid detected by the inlet temperature sensor 111 (hereinafter referred to as "inlet liquid temperature") Twi and the temperature of the used fluid detected by the outlet temperature sensor 112 (hereinafter referred to as "outlet liquid temperature") are determined. Two) is read, and the process moves to the next step S103.

In S103, the drive frequency Fcmp of the compressor 1 is set. The setting of the driving frequency Fcmp is based on, for example, the difference between the inlet liquid temperature Twi or the outlet liquid temperature Two and the target temperature, the amount of change in this difference over time, and the like.

In S104, it is determined whether or not the drive frequency Fcmp set in S103 is 0, that is, whether there is a condition for stopping the compressor 1. For example, if the inlet liquid temperature Twi becomes higher than the target temperature, the drive frequency Fcmp becomes 0 and the compressor 1 is stopped. If the drive frequency Fcmp is 0 (YES in S104), the process proceeds to S105, and if it is not 0 (NO in S104), the process proceeds to S106.

In S105, it is determined whether the drive frequency Fcmp set in the previous routine, that is, the previous routine, was 0. In other words, following the previous routine, this routine also determines whether the compressor 1 is stopped by determining whether the drive frequency Fcmp is 0. If the drive frequency Fcmp set in the previous routine is 0, the control in the current routine is ended and the process returns to the initial start. If it is not 0, it is assumed that the drive frequency Fcmp has become 0 in this routine, and the process advances to S107. Note that in the first routine immediately after the operation is turned on (first YES in S101), the previous value of Fcmp is set to "0" as its initial value.

In S106, it is determined whether the drive frequency Fcmp set in the previous routine was 0. In other words, by determining whether the driving frequency Fcmp, which was 0 in the previous routine, is no longer 0 in the current routine, it is determined whether or not the compressor 1 is being started. If the drive frequency Fcmp set in the previous routine is 0 (YES in S106), it is necessary to start the compressor 1 and the process advances to S109; if it is not 0 (NO in S106), the process continues until the current routine. Since the compressor 1 has already been started and the compressor 1 is in operation, the process advances to S110.

In S107, the compressor 1 is stopped. Then, at the same time or almost simultaneously, the belt heater 7 is energized in the subsequent S1208 to start the heating operation of the belt heater 7, thereby heating the compressor 1 which is currently stopped.

On the other hand, in S109, compressor startup control shown in FIG. 6 is executed. In this embodiment, the compressor startup control compares a temperature difference ΔTw corresponding to the difference between the detection signal of the inlet temperature sensor 111 and the detection signal of the outlet temperature sensor 112 with a predetermined temperature ΔTsl when starting the compressor 1. However, when the temperature difference ΔTw is greater than or equal to a predetermined value ΔTsl, the control is configured to prohibit starting the compressor 1. The predetermined value ΔTsl is set as a temperature within a range of approximately 3 to 5°C.

In S110, the compressor 1 is operated at the drive frequency Fcmp.

In the compressor startup control, in S201 of the flowchart shown in FIG. 6, the temperature difference ΔTw between the inlet liquid temperature Twi and the outlet liquid temperature Two is calculated, and it is determined whether the temperature difference ΔTw is greater than or equal to a predetermined value ΔTsl. judge. If the temperature difference ΔTw is greater than or equal to the predetermined value ΔTsl (YES in S201), it is determined that there is no flow of the fluid to be used in the first heat exchanger 2, and the process proceeds to S202, leaving the compressor 1 stopped. maintain. On the other hand, if it is less than the predetermined value ΔTsl (NO in S201), it is determined that the flow of the fluid to be used is occurring normally in the first heat exchanger 2, and the process proceeds to S209, where the compressor 1 is turned off. to start. In other words, when the compressor 1 is stopped, if the flow of the utilization fluid has already occurred normally in the first heat exchanger 2, the inlet liquid temperature Twi and the outlet liquid temperature Two will change due to heat transfer from the utilization fluid. Since the temperature of the fluid used is almost the same, it is judged to be normal.

S203 and subsequent steps subsequent to S202 are steps for confirming whether or not it is certain that there is no flow of utilization fluid in the first heat exchanger 2, and determining and displaying an abnormality.

In S203, it is determined whether a predetermined time has elapsed since the driving frequency Fcmp of the compressor 1 became 0, in other words, whether the state in which the temperature difference ΔTw is equal to or greater than the predetermined value ΔTsl continues for a predetermined time. Determine whether or not. If the predetermined time has elapsed (YES in S203), the process advances to S204; if the predetermined time has not elapsed (NO in S203), the process bypasses the processes after S204 and returns to the basic control routine shown in FIG. After finishing control by the routine, repeat the basic routine. This is because the accurate state of the fluid to be used cannot be detected from the inlet liquid temperature Twi and the outlet liquid temperature Two until after the compressor 1 has stopped for a certain period of time.

In S204, 1 is added to the count value CNT (CNT=CNT+1).

In S205, it is determined whether the count value CNT after addition has reached a predetermined value a. In other words, by determining whether or not a situation in which the temperature difference ΔTw is equal to or greater than the predetermined value ΔTsl continues for a predetermined period of time has occurred consecutively the number of times determined by the predetermined value a. This avoids erroneous judgments due to temporary events. If the predetermined value a has been reached (YES in S205), the process advances to S206, and if it has not reached the predetermined value (NO in S205), the process bypasses the processes after S206 and returns to the basic control routine. The value a is preferably about 3 to 5.

In S206, a determination is made that there is no flow of fluid in the first heat exchanger 2 (hereinafter referred to as "abnormality determination"), and the user is prompted to recognize that an abnormality has occurred. Perform display or notification. For example, the display section of the display device 114 is turned on to indicate the occurrence of an abnormality.

In subsequent S207, it is determined whether a reset operation has been performed by the user. If the reset operation has been performed (YES in S207), the process advances to S208, and if the reset operation has not been performed (NO in S207), the display indicating the occurrence of an abnormality continues. In other words, until the reset operation is performed, the determination in S207 is repeated and the activation of the compressor 1 is suspended. The reset operation can be performed, for example, by installing a reset button on the operation panel of the display device 114. The user's reset operation is performed by checking the operating status of the pump provided in the external device and the presence or absence of clogging in the piping inside the first heat exchanger 2 or the piping of the external device, and then confirming that there is no problem. It will be implemented if confirmed by

In S208, the abnormality determination is canceled, the display indicating the occurrence of an abnormality, etc. is stopped, the process returns to the basic routine, and the compressor 1 is enabled to operate.

In S209, the compressor 1 is started and operated at the drive frequency Fcmp set in S104 of the basic routine shown in FIG. In S210 following S209, heating of the compressor 1 is no longer necessary due to the start of operation of the compressor 1, so the power supply to the belt heater 7 is turned off, and the process returns to the basic routine shown in FIG. 5.

In order to reduce power consumption, the belt heater 7 is turned off after starting the compressor 1 (S210), but it may be continued to operate to compensate for the heat generated by the compressor 1 itself. In this case, the heat source unit U is always energized as long as it is connected to the power source 11, and the belt heater 7 continues to heat the compressor 1.

Figures 7 to 9 show examples of changes in the inlet liquid temperature Twi and the outlet liquid temperature Two in order to compare temperature changes in different situations. 7 is a graph showing changes in the inlet liquid temperature Twi, the outlet liquid temperature Two, and the temperature difference ΔTw in the case where the energization to 7 is cut off.

On the other hand, FIG. 8 shows the inlet liquid temperature Twi and the outlet liquid temperature Two in the case where the pump is stopped continuously after energization to the belt heater 7 is started and a state where there is no flow in the fluid to be used is maintained. and a graph showing changes in temperature difference ΔTw.

FIG. 9 shows the inlet liquid temperature Twi, the outlet liquid temperature Two, and the temperature difference ΔTw when the pump is started from a state where there is no flow of the utilized fluid and the circulation of the utilized fluid through the first heat exchanger 2 is started. and a graph showing changes in the flow rate Rcw of the fluid to be used.

In each of FIGS. 7 to 9, the dotted line indicates the inlet liquid temperature Twi, the solid line indicates the outlet liquid temperature Two, and the two-dot chain line indicates the temperature between the inlet liquid temperature Twi and the outlet liquid temperature Two. The difference ΔTw is shown. Furthermore, in FIG. 9, a fine dotted line indicates the flow rate Rcw of the fluid to be used.

In this embodiment, the first heat exchanger 2 and the compressor 1 are provided close to each other in the machine room B inside the casing C of the heat source unit U (FIG. 3), and Since the outlet of the fluid to be used for the exchanger 2 is provided above the inlet (FIG. 4), the outlet temperature sensor 112 is located above the inlet temperature sensor 111, and uses the belt heater 7 as a heat source. The amount of heat received through convective heat transfer is large. Therefore, if there is no other thermal influence, or if it exists, it can be considered that it is sufficiently small, the outlet liquid temperature Two, which is the temperature detected by the outlet temperature sensor 112, is the temperature detected by the inlet temperature sensor 111. The temperature becomes higher than the inlet liquid temperature Twi. In this embodiment, the temperature difference ΔTw is calculated as the difference obtained by subtracting the inlet liquid temperature Twi from the outlet liquid temperature Two (Two−Twi>0).

Here, referring to FIG. 7, if the belt heater 7 is de-energized and left in a state where there is no flow of the fluid to be used, that is, a state where the flow rate Rcw of the fluid to be used is 0 [L/min], the inlet The partial liquid temperature Twi and the outlet liquid temperature Two tend to approach each other over time and eventually converge to a temperature close to the outside air.

On the other hand, referring to FIG. 8, if the pump is stopped continuously after the belt heater 7 is energized and the fluid to be used remains in a state where there is no flow, the inlet liquid temperature Twi will be lower than the outside temperature. On the other hand, the outlet liquid temperature Two rises to exceed the temperature of the outside air, and a temperature difference ΔTw occurs between the outlet liquid temperature Two and the inlet liquid temperature Twi, and the temperature difference ΔTw is It expands over time and eventually tends to converge while maintaining a certain difference.

Furthermore, referring to FIG. 9, when the belt heater 7 is operated in a state where there is no flow of the fluid to be used and a temperature difference ΔTw is formed between the inlet liquid temperature Twi and the outlet liquid temperature Two, the belt heater 7 If the pump is started at time t0 to start the circulation of the fluid to be used through the first heat exchanger 2 while keeping it in operation, the water flow, that is, after the start of the circulation of the fluid to be used, the time will be The temperature difference ΔTw decreases over time, and tends to converge to 0 [° C.] or its vicinity after a certain amount of time has passed.

In this way, when the belt heater 7 is operated in a state where there is no flow of the fluid to be used, the air around the compressor 1 is warmed by the heat released by the belt heater 7, and the atmospheric temperature inside the machine room B increases. Along with this, the outlet temperature sensor 112 in the upper part of the machine room B and its installation location are also warmed mainly by convective heat transfer. Since there is no flow in the utilized fluid and the utilized fluid stagnates before and after the first heat exchanger 2, the amount of heat received from the belt heater 7 is retained at the outlet temperature sensor 112 and its installation location, and the outlet temperature sensor 112 and its installation location increases, reaching a temperature higher than the outside air. On the other hand, the inlet temperature sensor 111 and its installation location at the bottom of the machine room B are located near the bottom of the installation area of the belt heater 7, so they are not affected by the heat radiation from the belt heater 7. Maintain a temperature close to outside air.

On the other hand, if there is a flow of the utilized fluid in the first heat exchanger 2 while the compressor 1 is stopped, both the inlet temperature sensor 111 and the outlet temperature sensor 112 will have a large amount of heat transferred from the utilized fluid in terms of heat capacity. The effect of heat radiation from the belt heater 7 becomes relatively small. As a result, the inlet liquid temperature Twi detected by the inlet temperature sensor 111 and the outlet liquid temperature Two detected by the outlet temperature sensor 112 approach the temperature of the fluid to be used and become substantially the same temperature. Then, the temperature difference ΔTw between the outlet liquid temperature Two and the inlet liquid temperature Twi decreases to 0° C. or a temperature close to this, and becomes smaller than the set value ΔTsl.

The heat source unit U according to this embodiment has the above configuration. The effects obtained by this embodiment will be described below.

According to the present embodiment, when the belt heater 7 is operated, attention is paid to the transition of the temperature difference ΔTw between the inlet liquid temperature Twi and the outlet liquid temperature Two. By detecting the temperature difference ΔTw from the liquid temperature Two and comparing the temperature difference ΔTw with a preset value ΔTsl, it can be determined that there is no flow in the fluid to be used, for example, the pump of an external device has stopped. It is possible to make a determination without relying on an external input that informs the user of this, a so-called pump interlock mechanism. Furthermore, it is not necessary to add special parts such as a flow rate sensor for detecting the flow of the fluid to be used, and it is possible to suppress or reduce the number of parts.

Therefore, by making it a condition for starting the compressor 1 that there is no corresponding difference between the temperatures Twi and Two detected by the inlet temperature sensor 111 and the outlet temperature sensor 112, there is no flow in the fluid to be used. Prohibiting the start-up of the compressor 1 under these conditions, those without a pump interlock mechanism do not rely on this, while those equipped with a pump interlock mechanism supplement this, The heat source unit U can be more appropriately protected.

Furthermore, by adjusting a predetermined value ΔTsl to be compared with the temperature difference ΔTw, it is possible to check that although there is a flow in the fluid to be used, the flow rate Rcw is extremely small, for example, if there is a leak in the pipes p1 and p2 of the fluid to be used. It is possible to determine whether there are any problems, such as whether the

As described above, according to the present embodiment, the compressor 1 can be started under conditions where there is no flow in the utilized fluid or the flow rate is extremely small even if there is a flow, without depending on the so-called pump interlock mechanism. It is possible to protect the equipment of the heat source unit U from freezing and excessive load.

The inlet temperature sensor 111 and the outlet temperature sensor 112 are essential sensors for various controls of the heat source unit U, and by utilizing such existing parts, the heat source can be adjusted without adding new parts. It is possible to protect the entire unit U.

Furthermore, according to the present embodiment, the outlet of the fluid to be used for the first heat exchanger 2 is disposed above the inlet, and the amount of heat that the outlet or outlet temperature sensor 112 receives due to heat radiation from the belt heater 7 is reduced. By arranging the temperature sensor 111 to be larger than the amount of heat received by the inlet or inlet temperature sensor 111, it is possible to clearly distinguish the value that the temperature difference ΔTw should take between when there is a flow in the fluid to be used and when there is no flow. Become.

In the above description, by arranging the outlet temperature sensor 112 above the inlet temperature sensor 111, the inlet temperature sensor 111 and the outlet temperature sensor 112 are able to transfer heat by convection using the belt heater 7 as a heat source. The structure is designed to create a difference in the amount of heat received.

The cause of the difference in the amount of heat received by the inlet temperature sensor 111 and the outlet temperature sensor 112 is not limited to this. A difference may be caused in the amount of heat received by thermal radiation. For example, by arranging the outlet temperature sensor 112 closer to the belt heater 7 than the inlet temperature sensor 111, the inlet temperature sensor 111 receives the amount of heat that the outlet temperature sensor 112 receives due to thermal radiation from the belt heater 7. It is made larger than the amount of heat.

The arrangement is not limited to an arrangement that increases the amount of heat received by the outlet temperature sensor 112, but may be an arrangement that increases the amount of heat received by the inlet temperature sensor 111. For example, the inlet temperature sensor 111 may be placed above the outlet temperature sensor 112, or the inlet temperature sensor 111 may be placed closer to the compressor 1 or the belt heater 7 than the outlet temperature sensor 112. . In short, the amount of heat received from the belt heater 7 may be made different between the two sensors 111 and 112.

Furthermore, the amount of heat received by the inlet temperature sensor 111 and the outlet temperature sensor 112 is not limited to convection heat transfer and heat radiation, but may be influenced by heat conduction from the belt heater 7. In other words, since there is no substantial flow in the fluid used, the difference in the amount of heat received by the inlet temperature sensor 111 and the outlet temperature sensor 112 is not eliminated by the heat removed by the fluid used, and can be detected as a temperature difference ΔTw. It is good if you are in a certain situation.

In the above explanation, the case where it is applied to an air-cooled heat source unit U has been explained, but it is also possible to apply it to a water-cooled heat source unit, and in this case, not only the first heat exchanger 2 but also the second The heat exchanger 3 also becomes a water-refrigerant heat exchanger, and the fan F becomes unnecessary. Furthermore, the partition plate 7 inside the case C is not necessary, and the compressor 1, the first heat exchanger 2, the second heat exchanger 3, and other refrigeration cycle parts are housed in a single space inside the case C. be done.

Although not specified in the above description, the heat source unit U may or may not be provided with a pump interlock mechanism. The pump interlock mechanism detects the operating state of the pump and prohibits the compressor 1 from operating or starting when the pump is stopped. By providing a pump interlock mechanism, it is possible to achieve a superimposed failsafe. In particular, if there is a leak or blockage in the piping for the fluid being used, and the pump is operating but there is no substantial flow of the fluid being used, the pump may be operating and depending on the pump interlock mechanism, the compressor 1 may be closed. Although the operation cannot be prohibited, this embodiment can deal with this problem.

Furthermore, in the above explanation, it is assumed that the four-way valve 4 is installed in the heat source unit U and can supply cold water or hot water to an external device, but the four-way valve 4 is not limited to this. 4, it is also possible to configure the heat source unit U as a cold water generation device or a hot water generation device. In the thermoelectric unit U configured as a cold water generation device, the first heat exchanger 2 functions as an evaporator, and the second heat exchanger 3 functions as a condenser. On the other hand, in the thermoelectric unit U configured as a hot water generation device, the first heat exchanger 2 functions as a condenser, and the second heat exchanger 3 functions as an evaporator.

Furthermore, the system to which the heat source unit U is applied may have a circulation type configuration in which the fluid to be used is circulated between the system and an external device, or may have an open type configuration. For example, while receiving a supply of a utilization fluid such as water from an external device, the first heat exchanger 2 cools or heats the utilization fluid, and then supplies the cooled or heated utilization fluid to the external device. The adjusted fluid is used in an external device, used for other purposes, or used for heat recovery, and then discarded.

The concepts that can be derived from the above description are summarized below.
(1) A compressor that compresses refrigerant;
a heater arranged around the outer periphery of the compressor to be able to heat the compressor;
a first heat exchanger that exchanges heat between the refrigerant and the fluid to be used;
a casing that houses the compressor and the first heat exchanger;
a first temperature sensor installed at the inlet of the utilization fluid to the first heat exchanger;
a second temperature sensor installed at an outlet portion of the utilization fluid, the amount of heat received by heat radiation from the heater being different from that at the inlet portion with respect to the first heat exchanger;
Detection signals output from the first temperature sensor and the second temperature sensor are acquired, and when the heater is activated, a temperature difference corresponding to the difference between the detection signal of the first temperature sensor and the detection signal of the second temperature sensor is obtained. a controller that prohibits starting of the compressor when is equal to or greater than a predetermined value.
(2) The heat source unit according to claim 1, wherein the heater is a belt heater wrapped around the compressor.
(3) The inlet section and the outlet section receive different amounts of heat from the heater due to their disposed heights or distances from the heater being different from each other, according to (1) or (2) above. heat source unit.
(4) The heat source unit according to any one of (1) to (3) above, wherein the amount of heat received by the outlet section due to heat radiation from the heater is larger than the amount of heat received by the inlet section.
(5) The heat source unit according to any one of (1) to (4) above, wherein the fluid to be used is water.
(6) an expansion valve;
a second heat exchanger;
further comprising a refrigerant pipe arranged to be able to circulate the refrigerant between the compressor, the first heat exchanger, the expansion valve, and the second heat exchanger,
The first heat exchanger is configured to be able to cool the utilization fluid by heat exchange with the refrigerant,
The heat source unit according to any one of (1) to (5), wherein the second heat exchanger is configured to be able to release heat from the refrigerant after cooling the utilization fluid.
(7) The casing includes a partition plate that partitions the inside thereof,
The heat source unit according to any one of (1) to (6) above, wherein the compressor and the first heat exchanger are housed in the same space partitioned by the partition plate.
(8) a compressor that compresses a refrigerant, a heater that heats the compressor, a first heat exchanger that exchanges heat between the refrigerant and the fluid to be used, and provided in the first heat exchanger, a first temperature sensor and a second temperature sensor each receiving a different amount of heat due to heat radiation from the heater, and a controller that prohibits starting of the compressor based on a difference in detected temperatures of the first and second temperature sensors; A heat source unit equipped with

Although several embodiments of the invention have been described, these embodiments are presented by way of example only 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, changes, etc. can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention, as well as within the scope of the invention described in the claims and its equivalents.

U... Heat source unit, C... Housing, blower room A, machine room B, 1... Compressor, 2... First heat exchanger, 3... Second heat exchanger, 7... Belt heater, 9... Partition plate, p1 ...Inlet side piping, p2...Outlet side piping, 11...Power source, 101...Controller, 111...Inlet temperature sensor, 112...Outlet temperature sensor, 113...Operation switch, 115...Relay.

Claims (8)

a compressor that compresses refrigerant;
a heater that heats the compressor;
a first heat exchanger that exchanges heat between the refrigerant and the fluid to be used;
a first temperature sensor installed in the first heat exchanger;
a second temperature sensor installed in the first heat exchanger at a location where the amount of heat received by heat radiation from the heater is different from that of the first temperature sensor;
a controller that prohibits starting of the compressor based on a difference in temperature detected by the first and second temperature sensors;
A heat source unit equipped with a compressor that compresses refrigerant;
a heater arranged around the outer periphery of the compressor to be able to heat the compressor;
a first heat exchanger that exchanges heat between the refrigerant and the fluid to be used;
a casing that houses the compressor and the first heat exchanger;
a first temperature sensor installed at the inlet of the utilization fluid to the first heat exchanger;
a second temperature sensor installed at an outlet portion of the utilization fluid, the amount of heat received by heat radiation from the heater being different from that at the inlet portion with respect to the first heat exchanger;
Detection signals output from the first temperature sensor and the second temperature sensor are acquired, and when the heater is activated, a temperature difference corresponding to the difference between the detection signal of the first temperature sensor and the detection signal of the second temperature sensor is obtained. is a predetermined value or more, a controller that prohibits starting of the compressor;
A heat source unit equipped with The heat source unit according to claim 2, wherein the heater is a belt heater wrapped around the compressor. 3. The heat source unit according to claim 2, wherein the inlet part and the outlet part receive different amounts of heat from the heater because they are arranged at different heights or at different distances from the heater. The heat source unit according to claim 4, wherein the outlet section is located above the inlet section or closer to the heater. The heat source unit according to claim 1, wherein the utilization fluid is water. an expansion valve;
a second heat exchanger;
further comprising a refrigerant pipe arranged to be able to circulate the refrigerant between the compressor, the first heat exchanger, the expansion valve, and the second heat exchanger,
The first heat exchanger is configured to be able to cool the utilization fluid by heat exchange with the refrigerant,
The heat source unit according to any one of claims 1 to 6, wherein the second heat exchanger is configured to be able to release heat from the refrigerant after cooling the utilization fluid. The casing includes a partition plate that partitions the inside of the casing,
The heat source unit according to claim 2, wherein the compressor and the first heat exchanger are housed in the same space partitioned by the partition plate.

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