JP6644152B2 - Liquid level detecting device, heat pump system and liquid level detecting method - Google Patents

Description

  The present invention relates to a liquid level detection device, a heat pump system, and a liquid level detection method.

  2. Description of the Related Art There is known a technology for detecting a liquid level using a difference in physical property values (density, heat capacity, heat transfer coefficient, etc.) between a liquid and a gas. For example, Patent Literature 1 discloses a liquid level detection device using a resistor whose resistance value changes according to temperature. The liquid level detection device disclosed in Patent Document 1 disposes a resistor in a container in which a liquid is stored, heats the resistor, and then lowers the temperature of the resistor by a predetermined temperature difference. Based on the required heat release time, it is determined whether the surrounding material of the resistor is liquid or gas. At this time, the influence of the surrounding temperature is suppressed by using the temperature immediately before heating the resistor as a reference value of the temperature when heating the resistor.

JP 2004-37303 A

  However, the characteristics of individual resistors vary depending on individual differences of the resistors. Therefore, the method disclosed in Patent Literature 1 has a problem that the accuracy of detection is reduced due to such variation.

  The present invention has been made to solve the above-described problem, and has as its object to provide a liquid level detection device and the like that can detect a liquid level with high accuracy.

In order to achieve the above object, the liquid level detection device according to the present invention is
A first temperature sensor and a second temperature sensor different from the first temperature sensor, a liquid level detection device that detects a liquid level of a liquid contained in a container disposed therein,
After performing the first heat treatment for heating the first temperature sensor, said first performs a second heat treatment for heating the temperature sensor again, third heating the second temperature sensor Heating control means for executing a fourth heat treatment for heating the second temperature sensor again after the heat treatment ,
A first heating time taken until a first temperature is a temperature of the first temperature sensor in said first heat treatment is a temperature difference increases the provision of the first in the second heat treatment a second heating time the temperature required to make the temperature difference increases in the provision, the difference between, or the first rise of the first temperature for a time defined in the first heat treatment is increased Detecting the liquid level based on at least one of a value and a second increase value in which the first temperature has increased during the predetermined time in the second heat treatment , A third heating time required for the second temperature, which is the temperature of the second temperature sensor, to rise by the prescribed temperature difference in the third heat treatment, and the second heating time in the fourth heat treatment. Temperature required for the temperature of the specified temperature difference to rise 4 or the third heating value in which the second temperature has increased during the prescribed time in the third heating treatment, and the prescribed value in the fourth heating treatment. A liquid level detecting means for detecting the liquid level based on at least one of a difference between the second temperature and a fourth increase value during the time .

  In the present invention, after performing the first heating process of heating the temperature sensor disposed inside the container, the liquid level detection device performs the second heating process of heating the temperature sensor again, and performs the first heating process. A first heating time required for the temperature of the temperature sensor to increase by a specified temperature difference in the heating process, a second heating time required for the temperature to increase by a specified temperature difference in the second heating process, Or a first rise value in which the temperature rises during a prescribed time in the first heat treatment, and a second rise value in which the temperature rises during a prescribed time in the second heat treatment. , The liquid level of the liquid stored in the container is detected on the basis of at least one of the differences. Therefore, according to the present invention, the liquid level can be detected with high accuracy.

The figure which shows the structure of the air-conditioning system which concerns on Embodiment 1. Diagram showing the configuration of the compressor Enlarged sectional view of the liquid level sensor according to the first embodiment. FIG. 2 is a block diagram showing a hardware configuration of the liquid level detection device according to the first embodiment. Block diagram showing the functional configuration of the liquid level detection device FIG. 7 is a diagram showing a change in temperature of the resistor sensor according to the first embodiment. Flow chart showing the flow of a liquid level detection process executed by the liquid level detection device Flow chart showing the flow of the liquid level determination process Enlarged sectional view of a liquid level sensor according to Embodiment 2. FIG. 10 is a diagram showing a transition of the temperature of the resistor sensor in the second embodiment. FIG. 14 is a diagram showing a relationship between the temperature at the time of heating the resistor sensor and the ambient temperature in the third embodiment. Enlarged sectional view of a liquid level sensor according to Embodiment 4.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts have the same reference characters allotted. Note that items that are not particularly described in the second, third, and fourth embodiments are the same as those in the first embodiment.

(Embodiment 1)
<Configuration of air conditioning system>
FIG. 1 shows an air conditioning system 40 functioning as a heat pump system according to Embodiment 1 of the present invention. The air-conditioning system 40 is a facility for air-conditioning an air-conditioning area 45 which is a space to be air-conditioned. Air conditioning refers to adjusting the temperature, humidity, cleanliness, airflow, and the like of air in a space to be air-conditioned, and specifically includes heating, cooling, dehumidifying, humidifying, and air purifying. The air conditioning system 40 is installed in, for example, a detached house, an apartment house, a facility, a building, a factory, or the like, and operates by receiving power supply from a not-shown commercial power supply, a power generation facility, a power storage facility, or the like.

The air conditioning system 40 is a heat pump type air conditioner using, for example, CO ₂ (carbon dioxide) or HFC (hydrofluorocarbon) as a refrigerant. The air conditioning system 40 includes an indoor unit 41 installed indoors and an outdoor unit 42 installed outdoors. The indoor unit 41 and the outdoor unit 42 are connected via a refrigerant circuit 50 through which a refrigerant flows and a communication line 103.

  The indoor unit 41 includes an indoor heat exchanger 55, an indoor blower 57, and an indoor unit control unit 101. The outdoor unit 42 includes the compressor 1, a four-way valve 52, an outdoor heat exchanger 53, an expansion valve 54, an outdoor blower 56, and an outdoor unit control unit 100. The refrigerant circuit 50 circularly connects the compressor 1, the four-way valve 52, the outdoor heat exchanger 53, the expansion valve 54, and the indoor heat exchanger 55. Thus, a heat pump (refrigeration cycle) is configured.

  The compressor 1 compresses the refrigerant flowing through the refrigerant circuit 50 to increase the temperature and pressure of the refrigerant. The compressor 1 circulates the refrigerant circuit 50 (heat pump) by discharging the compressed refrigerant to the four-way valve 52. The compressor 1 includes an inverter circuit capable of changing a capacity (a delivery amount per unit) according to a driving frequency. The compressor 1 changes the capacity according to a control value instructed from the outdoor unit control unit 100.

  The four-way valve 52 is installed on the discharge side of the compressor 1. The four-way valve 52 allows the refrigerant discharged from the compressor 1 to flow into the outdoor heat exchanger 53 when the air conditioning system 40 performs the cooling operation, and discharges the refrigerant from the compressor 1 when the air conditioning system 40 performs the heating operation. The direction in which the refrigerant flows in the refrigerant circuit 50 is switched so that the refrigerant flowing into the indoor heat exchanger 55 flows.

  The outdoor heat exchanger 53 exchanges heat between cold and hot heat supplied by the refrigerant flowing through the refrigerant circuit 50 and outdoor air. When the outdoor blower 56 starts the blowing operation, a negative pressure is generated inside the outdoor unit 42 to suck in outdoor air. The sucked air is supplied to the outdoor heat exchanger 53, and after being heat-exchanged by the outdoor heat exchanger 53, is blown out outdoors. The expansion valve 54 is provided between the indoor heat exchanger 55 and the outdoor heat exchanger 53. The opening of the expansion valve 54 is adjusted so that the refrigerant decompresses and expands. The expansion valve 54 is, for example, an electronic expansion valve whose opening can be variably controlled.

  The indoor heat exchanger 55 exchanges heat between cold and hot heat supplied from the refrigerant flowing through the refrigerant circuit 50 and air in the air conditioning area 45. The air heat exchanged by the indoor heat exchanger 55 is supplied to the air conditioning area 45 as conditioned air. Thereby, the air conditioning area 45 is cooled and heated. When starting the blowing operation, the indoor blower 57 generates a negative pressure inside the indoor unit 41 and sucks the air in the air conditioning area 45. The sucked air is supplied to the indoor heat exchanger 55, heat-exchanged by the indoor heat exchanger 55, and then blown out to the air conditioning area 45. As the amount of heat exchange between the refrigerant and the air in the indoor heat exchanger 55 increases, the cooling capacity or the heating capacity of the air conditioning system 40 increases. The cooling capacity and the heating capacity are adjusted by changing the frequency of the compressor 1.

  Although not shown, the outdoor unit control unit 100 and the indoor unit control unit 101 each include a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a communication interface, and a readable and writable nonvolatile semiconductor. It has a memory and the like. In the outdoor unit control unit 100 and the indoor unit control unit 101, the CPU controls the outdoor unit 42 and the indoor unit 41 by executing a control program stored in the ROM while using the RAM as a work memory.

  The outdoor unit control unit 100 and the indoor unit control unit 101 are connected by a communication line 103, cooperate with each other by transmitting and receiving various signals via the communication line 103, and control the entire air conditioning system 40. More specifically, the outdoor unit control unit 100 controls the drive frequency of the compressor 1, the switching of the four-way valve 52, the rotation speed of the outdoor blower 56, and the opening of the expansion valve 54. The indoor unit control unit 101 controls the rotation speed of the indoor blower 57. As described above, the outdoor unit control unit 100 and the indoor unit control unit 101 output operation commands to various devices according to the operation commands given to the air conditioning system 40. Note that the communication line 103 may be a wired, wireless, or other communication medium.

  The indoor unit control unit 101 sends and receives various signals to and from the remote controller 102. A user inputs an operation command to the air conditioning system 40 by operating the remote controller 102. As the operation command, for example, a command to switch between operation and stop, a command to switch the operation mode (cooling, heating, dehumidification, humidification, moisturization, air cleaning or air blowing, etc.), a command to switch the target temperature, a command to switch the target humidity, a flow rate Switching command, wind direction switching command, timer switching command, and the like. The air conditioning system 40 starts operation according to the input operation command.

<Configuration of compressor 1>
Next, a configuration of the compressor 1 provided in the outdoor unit 42 will be described with reference to FIG. The compressor 1 is a device that compresses a refrigerant by various compression methods such as a rotary type, a screw type, and a scroll type. As shown in FIG. 2, the compressor 1 includes a suction pipe 2 for sucking a refrigerant, a discharge pipe 3 for discharging a refrigerant, a compression mechanism 4 which is a mechanism for compressing the refrigerant, and an electric motor for driving the compressor 1. 5, a shell 9 accommodating the compression mechanism 4 and the electric motor 5 therein, and a liquid level sensor 10 for detecting a liquid level.

  The suction pipe 2 sucks the gaseous refrigerant (hereinafter, referred to as “gas refrigerant”) supplied from the outdoor heat exchanger 53 or the indoor heat exchanger 55 through the refrigerant circuit 50 into the shell 9. The compression mechanism 4 is driven by the rotational force of the rotor of the electric motor 5 and compresses the gas refrigerant sucked by the suction pipe 2. The discharge pipe 3 discharges the high-pressure and high-temperature gas refrigerant compressed by the compression mechanism 4 from the inside of the shell 9 to the four-way valve 52.

  The oil 7 is stored in the lower part of the shell 9. The oil 7 is lubricating oil (also referred to as refrigerating machine oil) for lubricating the compression mechanism 4. The oil 7 is supplied to the compression mechanism 4 through an oil pump (not shown) in order to reduce friction when the compression mechanism 4 compresses the refrigerant.

  When the compressor 1 is stopped when the outside air temperature is low, the gas refrigerant in the shell 9 partially condenses into a liquid refrigerant (hereinafter, referred to as “liquid refrigerant”). Therefore, the gas refrigerant, the liquid refrigerant, and the oil 7 exist in the shell 9. The liquid refrigerant in the shell 9 may be present more than the oil 7 when the compressor 1 is started. Since a part of the liquid refrigerant is dissolved in the oil 7, when the amount of the liquid refrigerant changes, the amount of the oil 7 also changes. If the oil 7 in the shell 9 is too much, the motor 5 is filled with the oil 7 and the efficiency is reduced. If the amount of the oil 7 in the shell 9 is too small, the oil cannot be supplied to the compression mechanism 4, so that the friction of the compression mechanism 4 increases and causes a failure. If the amount of the liquid refrigerant is too large, the compression mechanism 4 may be insufficiently lubricated and may be broken. For this reason, it is necessary to control the amount of the oil 7 in the shell 9 to an appropriate amount. For this purpose, the level of the oil 7 is adjusted by installing the liquid level sensor 10 in the shell 9 and grasping the height of the oil level 6 by the liquid level sensor 10.

  The liquid level sensor 10 is a sensor having a function of detecting a liquid level (liquid level) of the liquid, and detects an oil level 6 formed at a lower portion of the compressor 1. The shell 9 functions as a container containing the oil 7 as a liquid whose liquid level is detected by the liquid level sensor 10.

  FIG. 3 shows an enlarged sectional view of the liquid level sensor 10. The left side of FIG. 3 shows the appearance of the liquid level sensor 10 viewed from a first direction (x direction) on a horizontal plane. The right side of FIG. 3 is the second direction (y-direction) on the horizontal plane, and shows the appearance of the liquid level sensor 10 viewed from inside the shell 9. As shown in FIG. 3, the liquid level sensor 10 includes a pair of terminals 11 through which electricity flows, and a resistor sensor 12 provided before the terminals 11. The resistor sensor 12 is disposed at a position protruding toward the inside of the shell 9 so as to contact the oil 7.

  The resistor sensor 12 is a temperature sensor that includes a temperature measuring resistor and utilizes the fact that the resistance value changes with temperature. The resistor sensor 12 is, for example, an NTC (Negative Temperature Coefficient) sensor or a PTC (Positive Temperature Coefficient) sensor. The NTC sensor is a sensor having a negative temperature coefficient whose resistance decreases as the temperature increases. The PTC sensor is a sensor having a positive temperature coefficient whose resistance increases as the temperature rises.

  The resistor sensor 12 self-heats by applying electricity, and determines whether its surroundings are liquid or gas based on the temperature response at that time. The resistor sensor 12 has a certain relationship between its own heat (temperature) when it generates heat and its resistance value. For example, when the resistor sensor 12 is a PTC sensor, a proportional relationship is established between its own temperature and its resistance value. When the resistor sensor 12 is an NTC sensor, an inversely proportional relationship is established between its own temperature and its resistance.

<Configuration of Liquid Level Detection Device 100 (Outdoor Unit Control Unit 100)>
Next, a configuration of an outdoor unit control unit 100 (hereinafter, referred to as “liquid level detection device 100”) functioning as a liquid level detection device according to Embodiment 1 will be described. The liquid level detecting device 100 detects the oil level 6 of the oil 7 stored in the shell 9 of the compressor 1. As shown in FIG. 4, the liquid level detection device 100 includes an arithmetic circuit (control unit) 31, a clock unit 32, a power supply circuit 33, a storage unit 34, and a communication interface 35. These components are connected via a bus 39.

  The control unit (arithmetic circuit) 31 includes a CPU, a ROM, a RAM, and the like, and performs overall control of the liquid level detection device 100. The CPU can also be called a central processing unit, a central processing unit, a processor, a microprocessor, a microcomputer, a DSP (Digital Signal Processor), or the like. In the control unit 31, the CPU reads out programs and data stored in the ROM, and executes various operations using the RAM as a work area.

  The clock unit 32 is a clock device that includes an RTC (Real Time Clock) and continues clocking even while the power of the liquid level detection device 100 is off.

  The power supply circuit 33 generates electric power required to heat the resistor sensor 12 and supplies the electric power to the liquid level sensor 10. The power supply circuit 33 is connected to the liquid level sensor 10 via a power line for supplying power to the liquid level sensor 10. The power supply circuit 33 causes a current to flow through the resistor sensor 12 by applying a voltage between the terminals 11 at both ends of the resistor sensor 12 to cause the resistor sensor 12 to generate heat.

  The storage unit 34 is a nonvolatile semiconductor memory such as a flash memory, an EPROM (Erasable Programmable ROM) or an EEPROM (Electrically Erasable Programmable ROM), and plays a role as a so-called secondary storage device (auxiliary storage device). . The storage unit 34 stores various programs and data used by the control unit 31 to perform various processes, and various data generated or acquired by the control unit 31 performing various processes.

  The storage unit 34 stores a temperature table 36. The temperature table 36 is a table showing the correspondence between the resistance value of the resistor sensor 12 and the temperature. In accordance with the resistor sensor 12 installed in the compressor 1, a temperature table 36 suitable for the resistor sensor 12 is prepared in advance and stored in the storage unit 34.

  The communication interface 35 is an interface for communicating with the indoor unit control unit 101 and the remote controller 102 via the communication line 103. The communication interface 35 receives an operation command for the outdoor unit 42 or a command for changing the drive frequency of the compressor 1 from the indoor unit control unit 101 and the remote controller 102. In addition, the communication interface 35 transmits liquid level detection information, status information of the outdoor unit 42, and the like to the indoor unit control unit 101 and the remote controller 102.

  Next, a functional configuration of the liquid level detection device 100 will be described with reference to FIG. As shown in FIG. 5, the liquid level detection device 100 functionally includes a heating control unit 110, a temperature acquisition unit 120, a liquid level detection unit 130, an information output unit 140, and a heat pump control unit 150. Prepare. Each of these functions is realized by software, firmware, or a combination of software and firmware. The software and firmware are described as programs and stored in the ROM or the storage unit 34. Then, the control unit (arithmetic circuit) 31 implements each function by executing a program stored in the ROM or the storage unit 34. Note that a system including the liquid level detection device 100 and the liquid level sensor 10 is referred to as a liquid level detection system 200.

  The heating control unit 110 executes a first heating process of heating the resistor sensor 12 disposed inside the shell 9 and then executes a second heating process of heating the resistor sensor 12 again. More specifically, the heating control unit 110 supplies power to the liquid level sensor 10 via the power supply circuit 33, and applies a voltage between the terminals 11 of the liquid level sensor 10. Thereby, the heating control unit 110 heats the resistor sensor 12. The heating control unit 110 is realized by the control unit 31 cooperating with the clock unit 32 and the power supply circuit 33.

  The temperature acquiring unit 120 acquires the temperature of the resistor sensor 12 while the heating control unit 110 is heating the resistor sensor 12. More specifically, the temperature acquisition unit 120 measures the voltage applied between the terminals 11 of the liquid level sensor 10 by the power supply circuit 33 and the current flowing between the terminals 11. Then, the temperature acquisition unit 120 calculates the resistance value of the resistor sensor 12 by dividing the obtained voltage value by the current value. After calculating the resistance value, the temperature obtaining unit 120 obtains the temperature of the resistor sensor 12 by referring to the temperature table 36 stored in the storage unit 34 and calculating the temperature corresponding to the calculated resistance value. . The temperature acquisition unit 120 is realized by the control unit 31 cooperating with the power supply circuit 33 and the storage unit 34.

  FIG. 6 shows a transition of the temperature of the resistor sensor 12 when the resistor sensor 12 is heated by the heating control unit 110. 6, the horizontal axis represents time, and the vertical axis represents the temperature detected by the resistor sensor 12. The heating control unit 110 executes the heating process illustrated in FIG. 6 while referring to the temperature of the resistor sensor 12 acquired by the temperature acquisition unit 120.

  More specifically, the heating control unit 110 starts the first heating process at time t1 (0) when the temperature of the resistor sensor 12 is the first temperature T1. The first temperature T1 is a temperature of the resistor sensor 12 in a steady state. In the first heating process, the heating control unit 110 heats the resistor sensor 12 until the temperature of the resistor sensor 12 increases by a predetermined temperature difference ΔT. Then, at time t1 (1) at which the temperature of the resistor sensor 12 reaches the second temperature T2 (= T1 + ΔT), the heating control unit 110 stops heating the resistor sensor 12 and ends the first heating process. I do. The heating control unit 110 uses the timer 32 to measure the time Δt1 (= t1 (1) −t1 (0)) required for the temperature of the resistor sensor 12 to rise by the specified temperature difference ΔT in the first heating process. It is measured and stored in the RAM as the first heating time.

  When the first heat treatment is completed, the temperature of the resistor sensor 12 decreases. The heating control unit 110 starts the second heating process at time t2 (0) after the temperature of the resistor sensor 12 has decreased to the first temperature T1. In the second heating process, the heating control unit 110 heats the resistor sensor 12 again until the temperature of the resistor sensor 12 increases by a predetermined temperature difference ΔT. Then, at time t2 (1) at which the temperature of the resistor sensor 12 reaches the second temperature T2, the heating control unit 110 stops heating the resistor sensor 12 and ends the second heating process. The heating control unit 110 measures the time Δt2 (= t2 (1) −t2 (0)) required for the temperature of the resistor sensor 12 to rise by the specified temperature difference ΔT in the second heating process by the timer unit 32. It is measured and stored in the RAM as the second heating time.

  The heating control unit 110 thus intermittently repeats the heating process of the resistor sensor 12 until the temperature of the resistor sensor 12 rises from the first temperature T1 by the specified temperature difference ΔT. Thereby, heating control section 110 acquires heating times Δt1, Δt2,... Required for the temperature of resistor element sensor 12 to rise by temperature difference ΔT in each heating process. The specified temperature difference ΔT is, for example, 5 degrees or 10 degrees, and is stored in the ROM or the storage unit 34 in advance.

  Returning to the description of the functional configuration of the liquid level detection device 100 shown in FIG. The liquid level detection unit 130 determines the first heating time Δt1 required for the temperature of the resistor sensor 12 to rise by the specified temperature difference ΔT in the first heating process, and the resistance sensor 12 in the second heating process. The liquid level is detected based on a difference between the second heating time Δt2 required for the temperature of the second heating element to rise by the specified temperature difference ΔT. The liquid level detection unit 130 is realized by the control unit 31.

  More specifically, when the substance around the resistor sensor 12 is not changed as a liquid or a gas, the heating time for increasing the temperature of the resistor sensor 12 by the temperature difference ΔT does not change. Therefore, the difference between the first heating time Δt1 and the second heating time Δt2 becomes small. On the other hand, when the material around the resistor sensor 12 changes from liquid to gas or from gas to liquid, the heating time changes. Generally, a liquid has a larger heat capacity than a gas. Therefore, when the material around the resistor sensor 12 is a liquid, the resistance of the resistor sensor 12 is larger than when the material around the resistor sensor 12 is a gas. The time required for the temperature of No. 12 to rise by the temperature difference ΔT becomes relatively long. Therefore, by comparing the first heating time Δt1 and the second heating time Δt2, it is possible to detect whether or not the state of the substance around the resistor sensor 12 has changed between liquid and gas. it can.

  For example, when the second heating time Δt2 is longer than the first heating time Δt1 by a first threshold time or more, the oil level 6 in the shell 9 rises between the first heat treatment and the second heat treatment. Thus, it can be determined that the substance around the resistor sensor 12 has changed from gas to liquid. Therefore, the liquid level detection unit 130 determines whether the second heating time Δt2 is longer than the first heating time Δt1 by a first threshold time or more, and determines that the second heating time Δt2 is equal to the first heating time Δt2. If it is greater than Δt1 by the first threshold time or more, it is detected that the oil level 6 has risen above the position of the resistor sensor 12.

  Conversely, when the second heating time Δt2 is shorter than the first heating time Δt1 by a second threshold time or more, the oil level 6 in the shell 9 falls between the first heating processing and the second heating processing. Thus, it can be determined that the substance around the resistor sensor 12 has changed from a liquid to a gas. Therefore, the liquid level detection unit 130 determines whether the second heating time Δt2 is shorter than the first heating time Δt1 by a second threshold time or more, and determines whether the second heating time Δt2 is equal to the first heating time Δt2. When it is smaller than Δt1 by the second threshold time or more, it is detected that the oil level 6 has dropped below the position of the resistor sensor 12.

  In addition, the liquid level detection unit 130 determines that neither of the above cases, that is, the second heating time Δt2 is smaller than the time obtained by adding the first threshold time to the first heating time Δt1, and the first heating time If it is longer than the time obtained by subtracting the second threshold time from Δt1, it is detected that the oil level 6 has not changed beyond the position of the resistor sensor 12. Note that the first threshold time and the second threshold time may be the same or different. The first threshold time and the second threshold time are preset and stored in the ROM or the storage unit 34.

  The information output unit 140 outputs information indicating an abnormality when the liquid level detected by the liquid level detection unit 130 satisfies a specific condition. The specific condition is a predetermined condition that is satisfied when the amount of the oil 7 in the shell 9 is abnormal. For example, when the resistor sensor 12 is disposed at a height corresponding to the lower limit value allowed as the amount of the oil 7 in the shell 9, a specific condition is that the liquid level is The condition is satisfied when it is detected that the position has dropped below the position. On the other hand, when the resistor sensor 12 is disposed at a height corresponding to the upper limit value allowed as the amount of the oil 7 in the shell 9, a specific condition is that the liquid level is The condition is satisfied when it is detected that the sensor 12 has risen above the position of the sensor 12. Alternatively, the specific condition may be satisfied when the phenomenon that the liquid level falls below or rises above the position of the resistor sensor 12 occurs for a longer time than a predetermined time or more frequently than a predetermined frequency. .

  When the liquid level satisfies a specific condition, the information output unit 140 outputs information indicating that an abnormality has occurred to the remote controller 102 or a remote monitoring device such as an external information processing device. Alternatively, the information output unit 140 may store a flag that can be confirmed by the service provider in the RAM or the storage unit 34 as an error signal. The information output unit 140 is realized by the control unit 31 cooperating with the communication interface 35 or the storage unit 34 or the like.

  The heat pump controller 150 controls the heat pump according to the liquid level detected by the liquid level detector 130. For example, when it is detected that the liquid level has dropped below the position of the resistor sensor 12, or the phenomenon that the liquid level has dropped below the position of the resistor sensor 12 is longer than a predetermined time, or a predetermined time has elapsed. If the frequency is higher than the predetermined frequency, the heat pump control unit 150 lowers the drive frequency of the compressor 1. This is because if the compressor 1 is operated at a high frequency when the amount of the oil 7 in the shell 9 is insufficient, a high load is applied to the compressor 1 and the possibility of the compressor 1 being broken is high. In the above case, the heat pump control unit 150 opens the valve of the oil return circuit from the oil separator (not shown) so that the oil 7 discharged from the compressor 1 to the refrigerant circuit and the oil separator is opened. Is collected early. The heat pump control unit 150 is realized by the control unit 31 cooperating with the communication interface 35.

  The flow of the liquid level detection process executed in the liquid level detection device 100 configured as described above will be described with reference to the flowchart shown in FIG.

  The liquid level detection process shown in FIG. 7 is periodically executed at a preset cycle in a state where power is supplied to the liquid level detection device 100. The liquid level detection process is also executed when an instruction is input from the user via the remote controller 102.

  When the liquid level detection process starts, the control unit 31 starts heating the resistor sensor 12 (step S1). More specifically, the control unit 31 supplies electric power to the liquid level sensor 10 via the power supply circuit 33 to flow electricity to the resistor sensor 12. Thereby, the control unit 31 starts a first heating process for heating the resistor sensor 12. In the example of FIG. 6, at time t1 (0) when the temperature of the resistor sensor 12 is the first temperature T1, the control unit 31 starts the first heating process. At this time, the control unit 31 starts time measurement by the time measurement unit 32.

  When the first heating process is started, the control unit 31 determines whether or not the temperature of the resistor sensor 12 has increased by a specified temperature difference ΔT (step S2). More specifically, the control unit 31 functions as the temperature acquisition unit 120 while heating the resistor sensor 12, and calculates the resistance value from the voltage value and the current value of the resistor sensor 12. Then, the control unit 31 refers to the temperature table 36 and converts the calculated resistance value into a temperature. As described above, while heating the resistor sensor 12, the control unit 31 monitors the temperature and determines whether or not the specified temperature difference ΔT has been reached from the start of heating.

  If the temperature of the resistor sensor 12 has not risen by the specified temperature difference ΔT (step S2; NO), the control unit 31 keeps the process at step S2 and continues the first heating process. On the other hand, when the temperature of the resistor sensor 12 rises by the specified temperature difference ΔT (Step S2; YES), the control unit 31 stops supplying power to the liquid level sensor 10, thereby causing the The heating is stopped (step S3). In the example of FIG. 6, the control unit 31 stops heating the resistor sensor 12 at time t1 (1) when the temperature of the resistor sensor 12 is the second temperature T2, and ends the first heating process. At this time, the control unit 31 ends the timing by the timing unit 32.

  When the first heating process is completed, the control unit 31 stores the time Δt1 from the start time to the end time measured by the timer 32 in the RAM as the first heating time (step S4).

  After ending the first heating time and decreasing the temperature of the resistor sensor 12 to the first temperature T1, the controller 31 restarts heating of the resistor sensor 12 (step S5). More specifically, the control unit 31 supplies electric power to the liquid level sensor 10 via the power supply circuit 33 to flow electricity to the resistor sensor 12. Thereby, the control unit 31 starts the second heating process of heating the resistor sensor 12. In the example of FIG. 6, at time t2 (0) when the temperature of the resistor sensor 12 is the first temperature T1, the control unit 31 starts the second heating process. At this time, the control unit 31 starts time measurement by the time measurement unit 32.

  When the second heating process is started, the control unit 31 determines whether or not the temperature of the resistor sensor 12 has increased by a specified temperature difference ΔT (step S6). More specifically, the control unit 31 functions as the temperature acquisition unit 120 while heating the resistor sensor 12, and calculates the resistance value from the voltage value and the current value of the resistor sensor 12. Then, the control unit 31 refers to the temperature table 36 and converts the calculated resistance value into a temperature. As described above, while heating the resistor sensor 12, the control unit 31 monitors the temperature and determines whether or not the specified temperature difference ΔT has been reached from the start of heating.

  If the temperature of the resistor sensor 12 has not risen by the specified temperature difference ΔT (step S6; NO), the control unit 31 stops the process at step S6 and continues the first heating process. On the other hand, when the temperature of the resistor sensor 12 rises by the specified temperature difference ΔT (Step S6; YES), the control unit 31 stops supplying power to the liquid level sensor 10, thereby causing the resistor sensor 12 to stop operating. The heating is stopped (Step S7). In the example of FIG. 6, the control unit 31 stops heating the resistor sensor 12 at time t2 (1) when the temperature of the resistor sensor 12 is the second temperature T2, and ends the second heating process. At this time, the control unit 31 ends the timing by the timing unit 32.

  When the second heating process is completed, the control unit 31 stores the time Δt2 from the start time to the end time measured by the clock unit 32 in the RAM as the second heating time (step S8). The control unit 31 functions as the heating control unit 110 in steps S1 to S8 in which such two heating processes are performed.

  When the first heating process and the second heating process are completed, the control unit 31 executes a liquid level determination process based on the first heating time Δt1 and the second heating time Δt2 (step S9). ). More specifically, the control unit 31 determines whether the oil level 6 in the shell 9 has risen or fallen below the position where the resistor sensor 12 is provided. In step S9, the control unit 31 functions as the liquid level detection unit 130. The details of the liquid level determination process in step S9 will be described with reference to the flowchart shown in FIG.

  When the determination process of the liquid level in FIG. 8 starts, the control unit 31 determines whether or not the second heating time Δt2 is equal to or longer than a time obtained by adding the first threshold time to the first heating time Δt1 ( Step S91). As a result of the determination, if the second heating time Δt2 is equal to or longer than the time obtained by adding the first threshold time to the first heating time Δt1 (step S91; YES), the first heating process is switched to the second heating process. In the meantime, the material around the resistor sensor 12 has changed from gas to liquid. Therefore, the controller 31 detects that the liquid level has risen from the position of the resistor sensor 12 (step S92).

  On the other hand, when the second heating time Δt2 is not longer than the time obtained by adding the first threshold time to the first heating time Δt1 (step S91; NO), the control unit 31 then proceeds to the second heating time Δt2. It is determined whether the heating time Δt2 is equal to or less than the time obtained by subtracting the second threshold from the first heating time Δt1 (step S93). If the result of the determination is that the second heating time Δt2 is equal to or less than the time obtained by subtracting the second threshold value from the first heating time Δt1 (step S93; YES), from the first heating process to the second heating process During this time, the material around the resistor sensor 12 changes from a liquid to a gas. Therefore, the controller 31 detects that the liquid level has dropped below the position of the resistor sensor 12 (step S94).

  Further, when the second heating time Δt2 is not shorter than the time obtained by subtracting the second threshold time from the first heating time Δt1 (step S93; NO), the time from the first heating processing to the second heating processing In addition, the substance around the resistor sensor 12 does not change as a liquid or a gas. Therefore, the controller 31 detects that the liquid level has not changed (step S95). Thus, the liquid level determination process in FIG. 8 is completed.

  Returning to the liquid level detection processing in FIG. When determining the liquid level in step S9, the control unit 31 executes a process according to the detection result (step S10). More specifically, when the liquid level satisfies a specific condition, the control unit 31 transmits information indicating that an abnormality has occurred to the remote controller 102 or a remote monitoring device such as an external information processing device. Output to When it is detected that the amount of the oil 7 in the shell 9 is insufficient due to the liquid level, the control unit 31 lowers the drive frequency of the compressor 1 or temporarily closes the valve of the oil return circuit. Open it wide. In step S10, the control unit 31 functions as the information output unit 140 or the heat pump control unit 150.

  Thus, the liquid level detection processing in FIG. 7 ends. The liquid level detecting device 100 grasps the amount of the oil 7 in the shell 9 by executing the liquid level detecting process from step S1 to step S10 as needed.

  As described above, the liquid level detecting device 100 according to the first embodiment heats the resistor sensor 12 whose resistance value changes according to the temperature twice, and performs the resistance sensor 12 in the two heating processes. The oil level 6 of the oil 7 stored in the shell 9 is detected based on the difference in the heating time required until the temperature of the oil rises by the specified temperature difference ΔT. As described above, by heating one resistor sensor 12 twice and comparing the heating times of the two times, it is possible to eliminate the influence of the individual difference of each sensor as compared with the case where a plurality of sensors are used. . Therefore, according to liquid level detecting apparatus 100 according to Embodiment 1, oil level 6 can be detected with high accuracy.

(Embodiment 2)
Next, a second embodiment of the present invention will be described.

  FIG. 9 shows an enlarged cross-sectional view of the liquid level sensor 10a according to the second embodiment. The left side of FIG. 9 illustrates the appearance of the liquid level sensor 10a as viewed from a first direction (x direction) on a horizontal plane. The right side of FIG. 9 is the second direction (y-direction) on the horizontal plane, and shows the appearance of the liquid level sensor 10 a as viewed from inside the shell 9. As shown in FIG. 9, the liquid level sensor 10 a includes three terminals 11 for passing electricity, and a first resistor sensor 12 a and a second resistor sensor 12 b provided at the ends of the three terminals 11. Prepare. That is, two resistor sensors 12a and 12b are arranged inside the shell 9. The configurations other than the liquid level sensor 10a in the compressor 1 and the air conditioning system 40 are the same as those in the first embodiment.

  The first resistor sensor 12a and the second resistor sensor 12b are the same sensors as the resistor sensor 12 in the first embodiment, respectively. Specifically, the first resistance sensor 12a and the second resistance sensor 12b generate heat by applying electricity, respectively, and use the fact that the resistance value changes according to the temperature. A sensor and a second temperature sensor.

  As shown in FIG. 9, the first resistor sensor 12 a and the second resistor sensor 12 b are horizontally arranged at a position protruding toward the inside of the shell 9 so as to be able to contact the oil 7. Have been. In other words, the first resistor sensor 12a and the second resistor sensor 12b are installed at the same height. Therefore, when the first resistor sensor 12a is in contact with the oil 7, the second resistor sensor 12b is also in contact with the oil 7.

  The liquid level detecting device 100 detects the oil level 6 inside the shell 9 of the compressor 1 using the liquid level sensor 10a including the two resistor sensors 12a and 12b. The hardware configuration of liquid level detecting apparatus 100 is the same as that of the first embodiment. Further, in the functional configuration of the liquid level detecting device 100, the description of the same parts as in the first embodiment will be omitted, and the parts different from the first embodiment will be described.

  After performing the first heating process of heating the first resistor sensor 12a, the heating control unit 110 performs the second heating process of heating the first resistor sensor 12a again. Further, after performing the third heating process of heating the second resistor sensor 12b, the heating control unit 110 executes the fourth heating process of heating the second resistor sensor 12b again. More specifically, the heating control unit 110 supplies power to the liquid level sensor 10 via the power supply circuit 33 to heat not only the first resistor sensor 12a but also the second resistor sensor 12b. I do.

  The temperature acquisition unit 120 determines the first temperature, which is the temperature of the first resistance sensor 12a, while the heating control unit 110 is heating the first resistance sensor 12a, And the second temperature which is the temperature of the second resistor sensor 12b during the heating of the resistor sensor 12b. The method for acquiring the temperature is the same as in the first embodiment. More specifically, the temperature acquisition unit 120 calculates a resistance value from the voltage value and the current value for each of the two resistor sensors 12a and 12b, and converts the resistance value into a temperature with reference to the temperature table 36. I do.

  FIG. 10 shows a transition of the temperature of the two resistor sensors 12a and 12b when the two resistor sensors 12a and 12b are heated by the heating control unit 110. In FIG. 10, the solid line represents the transition of the temperature of the first resistor sensor 12a, and the dashed line represents the transition of the temperature of the second resistor sensor 12b.

  The first heating process and the second heating process performed on the first resistor sensor 12a are the same as those in the first embodiment. More specifically, the heating control unit 110 starts the first heating process at the time t1 (0), and the time t1 (1) at which the temperature of the first resistor sensor 12a increases by a predetermined temperature difference ΔT. Until then, the first resistor sensor 12a is heated. After that, the heating control unit 110 starts the second heating process at time t2 (0), and performs the first heating process until time t2 (1) at which the temperature of the first resistor sensor 12a increases by a predetermined temperature difference ΔT. Is heated.

  The heating procedure in the third heating process and the fourth heating process performed on the second resistor sensor 12b is the same as the first heating process and the second heating process. However, the third heat treatment and the fourth heat treatment are executed at a different timing from the first heat treatment and the second heat treatment.

  More specifically, at time t1 ′ (0) after executing the first heating process and before starting the second heating process, the heating control unit 110 performs the third heating process. To start. In the third heating process, the heating control unit 110 heats the second resistor sensor 12b until time t1 '(1) at which the temperature of the second resistor sensor 12b rises by the specified temperature difference ΔT. After that, the heating control unit 110 starts the fourth heat treatment at time t2 '(0) after the start of the second heat treatment. In the fourth heating process, the heating control unit 110 heats the second resistor sensor 12b until time t2 '(1) at which the temperature of the second resistor sensor 12b rises by the specified temperature difference ΔT.

  More specifically, the heating control unit 110 starts the third heating process after ending the first heating process, and executes the second heating process after ending the third heating process. Further, the heating control unit 110 starts the fourth heating process after the second heating process is completed. As described above, when the heating of one of the two resistor sensors 12a and 12b is stopped, the heating control unit 110 heats the other resistor sensor.

  The liquid level detector 130 detects the liquid level of each of the two resistor sensors 12a and 12b that are alternately heated in this way. More specifically, the liquid level detection unit 130 determines the first heating time Δt1 required for the temperature of the first resistor sensor 12a to rise by a predetermined temperature difference ΔT in the first heating process, and the second heating time Δt1. The liquid level is detected based on the difference between the second heating time Δt2 required until the specified temperature difference ΔT rises in the heat treatment of the above. In addition, the liquid level detection unit 130 determines the third heating time Δt1 ′ required until the temperature of the second resistor sensor 12b rises by the specified temperature difference ΔT in the third heating process, and the fourth heating process , The liquid level is detected based on the difference between the fourth heating time Δt2 ′ required until the specified temperature difference ΔT rises.

  More specifically, the liquid level detection unit 130 determines whether the first heating time Δt1 is longer than the second heating time Δt2 by a first threshold time or more, and that the third heating time Δt1 ′ is longer than the fourth heating time Δt1 ′. When it is longer than the time Δt2 ′ by the first threshold time or more, it is detected that the liquid level has risen above the positions of the two resistor sensors 12a and 12b. In addition, the information output unit 140 determines that the first heating time Δt1 is shorter than the second heating time Δt2 by a second threshold time or more, and that the third heating time Δt1 ′ is longer than the fourth heating time Δt2 ′. When it is shorter than the second threshold time, it is detected that the liquid level has dropped below the positions of the two resistor sensors 12a and 12b. Note that the information output unit 140 and the heat pump control unit 150 execute processing according to the detection result by the liquid level detection unit 130, as in the first embodiment.

  As described above, the liquid level detection device 100 according to the second embodiment alternately heats the two resistor sensors 12a and 12b arranged in the shell 9 in the horizontal direction, and the two resistor sensors 12a and 12b are alternately heated. The oil level 6 in the shell 9 is detected based on the heating time obtained alternately from the sensors 12a and 12b. By using the two resistor sensors 12a and 12b in this way, the period of the liquid level detection can be reduced to half as compared with the case where only one resistor sensor 12 is used. As a result, the frequency of liquid level detection can be increased, so that it is possible to quickly respond to a sudden change in the liquid level. In addition, erroneous detection can be reduced.

  Note that three or more resistor sensors 12 can be arranged in the horizontal direction. N (N is a natural number) resistor sensors 12 are arranged in a horizontal direction inside the shell 9, and the heating level of each of the resistor sensors 12 is shifted to sequentially detect the liquid level, thereby obtaining one resistor. Compared to the case where only the body sensor 12 is used, the cycle of liquid level detection can be reduced to 1 / N.

(Embodiment 3)
Next, a third embodiment of the present invention will be described.

  In the second embodiment, the heating control unit 110 alternately heats the two resistor sensors 12a and 12b disposed in the shell 9 in the horizontal direction. In contrast, in the third embodiment, the heating control unit 110 intermittently heats only the first resistor sensor 12a, does not heat the second resistor sensor 12b, and The temperature of 12b is used as the ambient temperature.

  FIG. 11 shows a relationship between the temperature at the time of heating the resistor sensors 12a and 12b and the ambient temperature. As shown in FIG. 11, the temperature at the time of heating the resistor sensors 12a and 12b changes depending on the ambient temperature. Further, the temperature characteristics during heating differ depending on whether the surrounding substance is a liquid or a gas. Therefore, in order to accurately determine whether the substance surrounding the heated first resistor sensor 12a is a liquid or a gas, it is necessary to consider the surrounding temperature.

  In order to solve this, in the liquid level detection device 100 according to the third embodiment, the liquid level detection unit 130 determines the temperature of the second resistor sensor 12b that is not heated, that is, according to the ambient temperature. The first threshold time and the second threshold time are corrected. The first threshold time and the second threshold time are thresholds used when the liquid level detection unit 130 executes the determination processing from the difference between the first heating time Δt1 and the second heating time Δt2. The temperature of the unheated second resistor sensor 12b is acquired by the temperature acquisition unit 120, similarly to the temperature of the heated first resistor sensor 12a.

  More specifically, as shown in FIG. 11, as the surrounding temperature increases, the difference in temperature between when the surrounding substance is a liquid and when the surrounding substance is a gas decreases. Therefore, the liquid level detection unit 130 corrects the first threshold time and the second threshold time to be shorter when the ambient temperature is high than when the ambient temperature is low.

  As described above, by detecting the ambient temperature on one of the two resistor sensors 12a and 12b, the gas-liquid determination process by the liquid level detection unit 130 can be corrected. As a result, erroneous detection of the liquid level can be reduced. Further, even when the ambient temperature changes rapidly, the liquid level can be detected with high accuracy.

(Embodiment 4)
Next, a fourth embodiment of the present invention will be described.

  FIG. 12 shows an enlarged sectional view of a liquid level sensor 10b according to the fourth embodiment. The left side of FIG. 12 shows the appearance of the liquid level sensor 10b as viewed from a first direction (x direction) on a horizontal plane. The right side of FIG. 12 is the second direction (y-direction) on the horizontal plane, and shows the appearance of the liquid level sensor 10 b as viewed from the inside of the shell 9. As shown in FIG. 12, the liquid level sensor 10 b includes four terminals 11 for passing electricity, and a first resistor sensor 12 c and a second resistor sensor 12 d provided at the ends of the four terminals 11. Prepare. That is, two resistor sensors 12c and 12d are arranged inside the shell 9. The configurations other than the liquid level sensor 10b in the compressor 1 and the air conditioning system 40 are the same as those in the first embodiment.

  The first resistor sensor 12c and the second resistor sensor 12d are the same sensors as the resistor sensors 12, 12a, and 12b in the first and second embodiments, respectively. More specifically, the first resistor sensor 12c and the second resistor sensor 12d generate heat by applying electricity, respectively, and use the fact that the resistance value changes depending on the temperature. A sensor and a second temperature sensor.

  As shown in FIG. 12, the first resistor sensor 12c and the second resistor sensor 12d are arranged in the vertical direction at positions protruding toward the inside of the shell 9 so as to be able to contact the oil 7. Have been. In other words, the first resistor sensor 12c and the second resistor sensor 12d are installed at different heights. The second resistor sensor 12d is arranged at a position lower than the first resistor sensor 12c.

  The liquid level detection device 100 detects the oil level 6 inside the shell 9 of the compressor 1 using the liquid level sensor 10b including the two resistor sensors 12c and 12d. The hardware configuration of liquid level detecting apparatus 100 is the same as that of the first embodiment. Further, in the functional configuration of the liquid level detecting device 100, the description of the same parts as in the first embodiment will be omitted, and the parts different from the first embodiment will be described.

  The temperature acquisition unit 120 acquires a first temperature that is the temperature of the first resistor sensor 12c and a second temperature that is the temperature of the second resistor sensor 12d. The method for acquiring the temperature is the same as in the first embodiment. More specifically, the temperature acquisition unit 120 calculates a resistance value from the voltage value and the current value for each of the two resistor sensors 12c and 12d, and converts the resistance value into a temperature with reference to the temperature table 36. I do.

  During the operation of the compressor 1, the high-temperature gas refrigerant returns, so that a temperature difference may occur between the gas refrigerant and the oil at the bottom of the compressor 1. Therefore, the liquid and the gas may be distinguished only by comparing the temperatures of the liquid and the gas without heating the resistor sensors 12c and 12d. That is, when the heating control unit 110 is not heating the first resistor sensor 12c and the second resistor sensor 12d, the temperatures of the first resistor sensor 12c and the second resistor sensor 12d are equal to these temperatures. It depends on whether the surroundings are liquid or gas. In particular, when a liquid or gas having a large temperature difference from the inside of the shell 9 flows into the inside of the shell 9, the temperature difference between the liquid and the gas is large. Therefore, in such a case, it is detected whether or not the liquid level is between the two resistor sensors 12c, 12d by comparing the temperatures of the two resistor sensors 12c, 12d arranged at different heights. can do.

  Therefore, when the heating control unit 110 is not heating the first resistor sensor 12c and the second resistor sensor 12d, the liquid level detecting unit 130 sets the temperature of the first resistor sensor 12c to the second resistor sensor 12c. It is determined whether the temperature is higher than the temperature of the resistor sensor 12d by a specified value or more. As a result of the determination, when the temperature of the first resistor sensor 12c is higher than the temperature of the second resistor sensor 12d by a specified value or more, the liquid level detection unit 130 sets the liquid level to the first resistor sensor 12c and the second resistor sensor. It is detected that it is between the second resistor sensor 12d. This prescribed value is set in advance and stored in the ROM or the storage unit 34.

  On the other hand, when the heating control unit 110 is not heating the first resistor sensor 12c and the second resistor sensor 12d, the temperature of the first resistor sensor 12c becomes lower than the second resistor sensor 12d. If the temperature is not higher than the specified temperature by a specified value or more, the liquid level cannot be detected from the temperature difference between the two resistor sensors 12c and 12d. In this case, the heating control unit 110 heats the first resistor sensor 12c and the second resistor sensor 12d.

  More specifically, the heating control unit 110 performs the first heating process and the second heating process on the first resistor sensor 12c, and performs the third heating process on the second resistor sensor 12d. A heat treatment and a fourth heat treatment are performed. These first to fourth heat treatments are the same as those described in the second embodiment. However, it is not necessary to heat the first resistor sensor 12c and the second resistor sensor 12d alternately as in the second embodiment. The timing of each heat treatment can be freely set.

  The liquid level detecting unit 130 detects a liquid level for each of the two resistor sensors 12c and 12d. More specifically, the liquid level detection unit 130 determines the first heating time Δt1 required for the temperature of the first resistor sensor 12c to rise by a predetermined temperature difference ΔT in the first heating process, and the second heating time Δt1. The liquid level is detected based on the difference between the second heating time Δt2 required until the specified temperature difference ΔT rises in the heat treatment of the above. In addition, the liquid level detection unit 130 determines the third heating time Δt1 ′ required until the temperature of the second resistor sensor 12d rises by the specified temperature difference ΔT in the third heating process, and the fourth heating process , The liquid level is detected based on the difference between the fourth heating time Δt2 ′ required until the specified temperature difference ΔT rises. Since the two resistor sensors 12c and 12d are arranged at different heights in the vertical direction, the liquid level detection unit 130 can detect the liquid level at two points.

  More specifically, when the first heating time Δt1 is longer than the second heating time Δt2 by a first threshold time or more, the liquid level detecting unit 130 determines that the liquid level is equal to the position of the first resistor sensor 12c. It is detected that it has risen. In addition, the information output unit 140 determines that the first heating time Δt1 is shorter than the second heating time Δt2 by a second threshold time or more, and that the third heating time Δt1 ′ is the fourth heating time. When it is larger than Δt2 ′ by the first threshold time or more, it is detected that the liquid level is between the first resistor sensor 12c and the second resistor sensor 12d. Further, when the third heating time Δt1 ′ is shorter than the fourth heating time Δt2 ′ by a second threshold time or more, the information output unit 140 determines that the liquid level is lower than the position of the second resistor sensor 12d. Is detected. Note that the information output unit 140 and the heat pump control unit 150 execute processing according to the detection result by the liquid level detection unit 130, as in the first embodiment.

  As described above, the liquid level detecting device 100 according to the fourth embodiment detects the liquid level using the two resistor sensors 12c and 12d arranged at different heights inside the shell 9. If the temperature difference between the two resistive sensors 12c and 12d during non-heating is equal to or greater than a specified value, the liquid level can be detected without heating the two resistive sensors 12c and 12d. Thus, since the heating time can be reduced, power consumption can be reduced, and an energy saving effect can be obtained.

  Note that three or more resistor sensors 12 may be arranged at different heights. By providing the resistor sensors 12 at a number of different heights, the range in which the liquid level can be detected can be increased.

  When a plurality of resistor sensors 12 are used as in the second, third, and fourth embodiments, abnormality or deterioration of each sensor is determined by comparing the respective temperatures, resistance values, or responses at the time of heating. Can be found. In addition, an error of each sensor due to aged deterioration can be corrected using a deviation from an average value of a plurality of sensors.

(Modification)
Although the embodiments of the present invention have been described above, various modifications and applications are possible in practicing the present invention.

  For example, in the above embodiment, the air conditioning system 40 has been described as an example of the heat pump system according to the present invention. However, the heat pump system according to the present invention is not limited to the air conditioning system 40, and may be a refrigeration system or a hot water supply system as long as the compressor 1 compresses refrigerant and circulates the heat pump.

  Further, the liquid level detection device 100 according to the present invention is not limited to detecting the oil level 6 in the compressor 1 in the heat pump system, but may be any device that detects the liquid level of the liquid stored in the container. The present invention can be applied to any device, equipment, system, or the like. The liquid whose liquid level is detected may be water or various organic solvents. For example, as another example of use in a heat pump system, the liquid level detecting device 100 according to the present invention can be used for detecting a liquid level in an accumulator or a liquid reservoir. In this case, the liquid level detecting device 100 detects the liquid level between the gas refrigerant and the liquid refrigerant.

  In the above embodiment, the outdoor unit controller 100 functions as the liquid level detecting device 100 according to the present invention. However, in the present invention, devices other than the outdoor unit control unit 100, such as the indoor unit control unit 101 or the remote controller 102, may function as the liquid level detection device 100. In addition, a HEMS (Home Energy Management System) controller capable of integrally controlling each device in the house where the heat pump system is installed may function as the liquid level detection device 100, or may be a wide area such as the Internet. A server connected to the heat pump system via the network may function as the liquid level detection device 100.

  In the above embodiment, the resistor sensor 12 whose resistance changes according to the temperature functions as a temperature sensor. However, in the present invention, any sensor may be used as long as the temperature sensor is disposed inside the container and can measure its own temperature when heated by the heating control unit 110. good. For example, the temperature sensor does not need to have both a function as an element that generates heat and a function as an element that detects temperature as in the case of the resistor sensor 12. That is, an element (heating body) that generates heat may be provided separately from the temperature sensor.

  In the above embodiment, the heating control unit 110 controls the start and the end of the heating process of the resistor sensor 12 with reference to the temperature obtained from the resistance value of the resistor sensor 12. However, the resistance value can be used as it is instead of the temperature. For example, when the resistor sensor 12 is a PTC sensor, the resistance value is proportional to the temperature. Therefore, the same tendency can be obtained even if the ordinate of FIG. 6 is represented by a resistance value. Even if the resistor sensor 12 is an NPC sensor, the same tendency can be obtained by reversing the sign. Therefore, the heating control unit 110 can control the start and the end of the heating process of the resistor sensor 12 with reference to the resistance value of the resistor sensor 12.

  In the above-described embodiment, the liquid level detection unit 130 detects the liquid level based on the heating time until the temperature T of the resistor sensor 12 increases from the first temperature T1 by the specified temperature difference ΔT. . However, the liquid level detection unit 130 starts measuring time after a certain time has elapsed after the start of heating and the temperature of the resistor sensor 12 has risen, and continues heating until the temperature rises by a specified temperature difference ΔT from that time. The liquid level may be detected based on time. In particular, depending on the operation state of the heat pump, the initial temperature of the resistor sensor 12 may not be constant. Even in such a case, gas-liquid can be determined with high accuracy by measuring the heating time based on the specified temperature difference ΔT.

  In the above embodiment, the liquid level detection unit 130 detects the liquid level based on the heating time required until the temperature of the resistor sensor 12 increases by the specified temperature difference ΔT. However, the relationship between temperature and time may be reversed. More specifically, the liquid level detection unit 130 determines a first rising value in which the temperature of the resistor sensor 12 has risen during a specified time in the first heating process and a specified time in the second heating process. The liquid level may be detected based on the difference between the second rise value in which the temperature of the resistor sensor 12 has risen during the period. The prescribed time is, for example, 5 seconds or 10 seconds, and is stored in the ROM or the storage unit 34 in advance. In other words, the liquid level detection unit 130 detects the liquid level based on at least one of the difference between the first heating time and the second heating time or the difference between the first rising value and the second rising value. The surface level can be detected.

  The temperature rising during the same heating time is higher for gases than for liquids. Therefore, the liquid level detection unit 130 determines whether the second rising value is smaller than the first rising value by the first threshold value or more, and determines that the second rising value is the first rising value smaller than the first rising value. Is smaller than the threshold value, it is detected that the oil level 6 has risen above the position of the resistor sensor 12. The liquid level detection unit 130 also determines whether the second rise value is greater than the first rise value by a first threshold or more, and determines that the second rise value is the first rise value greater than the first rise value. Is larger than the threshold value, it is detected that the oil level 6 has dropped below the position of the resistor sensor 12. In addition, in neither of these cases, the liquid level detection unit 130 detects that the oil level 6 has not changed beyond the position of the resistor sensor 12. Then, in each of the above cases, the information output unit 140 outputs output information indicating a detection result by the liquid level detection unit 130. The first threshold and the second threshold are set in advance and stored in the ROM or the storage unit 34.

  In the second, third, and fourth embodiments, the relationship between the temperature and the time is reversed, and the liquid level detecting unit 130 sets the liquid level based on the difference between the first rise value and the second rise value. It may be detected. In this case, in the second embodiment, the liquid level detection unit 130 determines the third rising value in which the temperature of the second resistor sensor 12b has risen during the prescribed time in the third heating process, and the fourth rising value. The liquid level is detected based on a difference between a fourth rise value in which the temperature of the second resistor sensor 12b has risen during a predetermined time in the heat treatment. In the third embodiment, liquid level detecting section 130 corrects the first threshold value and the second threshold value according to the temperature around resistor sensor 12 being heated by heating control section 110. In the fourth embodiment, when the heating control unit 110 is not heating the two resistor sensors 12c and 12d, the liquid level detecting unit 130 sets the temperature of the first resistor sensor 12c to the second resistor sensor. If the temperature is not higher than the temperature of 12d by the specified value or more, the liquid level is set based on the difference between the first rise value and the second rise value or the difference between the third rise value and the fourth rise value. Detect.

  In the above-described embodiment, in the control unit 31 of the liquid level detection device 100, the CPU executes the program stored in the ROM or the storage unit 34, and thereby the heating control unit 110, the temperature acquisition unit 120, the liquid level detection unit 130 , The information output unit 140 and the heat pump control unit 150. However, in the present invention, the control unit 31 may be dedicated hardware. The dedicated hardware is, for example, a single circuit, a composite circuit, a programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. When the control unit 31 is dedicated hardware, the function of each unit may be realized by individual hardware, or the function of each unit may be realized by a single piece of hardware.

  In addition, a part of the function of each unit may be realized by dedicated hardware, and the other part may be realized by software or firmware. As described above, the control unit 31 can realize each of the above functions by hardware, software, firmware, or a combination thereof.

  By applying an operation program that defines the operation of the liquid level detecting device 100 according to the present invention to a computer such as an existing personal computer or an information terminal device, the computer functions as the liquid level detecting device 100 according to the present invention. It is also possible.

  The distribution method of such a program is arbitrary. For example, a computer-readable recording medium such as a CD-ROM (Compact Disk ROM), a DVD (Digital Versatile Disk), an MO (Magneto Optical Disk), or a memory card is used. The program may be stored in a medium and distributed, or may be distributed via a communication network such as the Internet.

  The present invention is capable of various embodiments and modifications without departing from the broad spirit and scope of the invention. Further, the above-described embodiment is for describing the present invention, and does not limit the scope of the present invention. That is, the scope of the present invention is shown not by the embodiments but by the claims. Various modifications made within the scope of the claims and equivalents thereof are considered to be within the scope of the present invention.

  INDUSTRIAL APPLICATION This invention can be employ | adopted suitably for a heat pump system etc.

Reference Signs List 1 compressor, 2 suction pipe, 3 discharge pipe, 4 compression mechanism, 5 motor, 6 oil level, 7 oil, 9 shell, 10, 10a, 10b liquid level sensor, 11 terminals, 12, 12a, 12b, 12c, 12d Resistor sensor, 31 control unit (arithmetic circuit), 32 clock unit, 33 power supply circuit, 34 storage unit, 35 communication interface, 36 temperature table, 39 bus, 40 air conditioning system, 41 indoor unit, 42 outdoor unit, 45 air conditioning area , 50 refrigerant circuit, 52 four-way valve, 53 outdoor heat exchanger, 54 expansion valve, 55 indoor heat exchanger, 56 outdoor blower, 57 indoor blower, 100 liquid level detection device (outdoor unit control unit), 101 indoor unit control unit , 102 remote controller, 103 communication line, 104 display unit, 110 heating control unit, 120 temperature acquisition unit, 130 liquid level detection unit, 14 Information output unit, 150 a heat pump control unit, 200 liquid level sensing system

Claims (16)

A first temperature sensor and a second temperature sensor different from the first temperature sensor, a liquid level detection device that detects a liquid level of a liquid contained in a container disposed therein,
After performing the first heat treatment for heating the first temperature sensor, said first performs a second heat treatment for heating the temperature sensor again, third heating the second temperature sensor Heating control means for executing a fourth heat treatment for heating the second temperature sensor again after the heat treatment ,
A first heating time taken until a first temperature is a temperature of the first temperature sensor in said first heat treatment is a temperature difference increases the provision of the first in the second heat treatment a second heating time the temperature required to make the temperature difference increases in the provision, the difference between, or the first rise of the first temperature for a time defined in the first heat treatment is increased Detecting the liquid level based on at least one of a value and a second increase value in which the first temperature has increased during the predetermined time in the second heat treatment , A third heating time required for the second temperature, which is the temperature of the second temperature sensor, to rise by the prescribed temperature difference in the third heat treatment, and the second heating time in the fourth heat treatment. Temperature required for the temperature of the specified temperature difference to rise 4, or a third rise value in which the second temperature has risen during the prescribed time in the third heat treatment, and the prescribed value in the fourth heat treatment. A liquid level detection unit that detects the liquid level based on at least one of a difference between the second temperature and a fourth increase value during the time .
Liquid level detection device. The liquid level detection unit detects the liquid level based on the difference between the first heating time and the second heating time,
The liquid level detecting device according to claim 1. The liquid level detection unit detects the liquid level based on the difference between the first rise value and the second rise value,
The liquid level detecting device according to claim 1. The liquid level detection unit may be configured to determine that the second heating time is longer than the first heating time by a first threshold time or more, or that the second rising value is the first rising time greater than the first rising time. When the liquid level is smaller than the threshold value, it is detected that the liquid level has risen above the position of the first temperature sensor.
The liquid level detecting device according to claim 1. The liquid level detection unit corrects the first threshold time or the first threshold according to a temperature around the first temperature sensor,
The liquid level detecting device according to claim 4. The liquid level detection unit may be configured to determine that the second heating time is shorter than the first heating time by a second threshold time or more, or that the second rise value is a second rise time smaller than the first rise time. When it is larger than the threshold of, it is detected that the liquid level has dropped below the position of the first temperature sensor,
The liquid level detecting device according to claim 1. The liquid level detection unit corrects the second threshold time or the second threshold according to a temperature around the first temperature sensor,
The liquid level detecting device according to claim 6. The first temperature sensor and the second temperature sensor are arranged side by side in a horizontal direction,
The heating control means may start the third heating process after the first heating process is started and before the second heating process is started, and may perform the fourth heating process. Is started after starting the second heat treatment,
The liquid level detecting device according to claim 1 . The second temperature sensor is disposed at a position lower than the first temperature sensor,
The liquid level detecting device according to claim 1 . The liquid level sensing means, said heating control means in the case that is not heated and said second temperature sensor and the first temperature sensor, the first temperature is the specified value or higher than the second temperature If high, detecting that the liquid level is between the first temperature sensor and the second temperature sensor;
The liquid level detecting device according to claim 9 . The liquid level sensing means, said heating control means in the case that is not heated and said second temperature sensor and the first temperature sensor, the first temperature is the specified value or higher than the second temperature If not high, the difference between the first heating time and the second heating time, the difference between the third heating time and the fourth heating time, the first rise value and the second The liquid level is detected based on at least one of the difference between the rising value and the third rising value and the fourth rising value,
The liquid level detecting device according to claim 10 . It said first temperature sensor is Ri first resistor sensor der whose resistance value changes in response to the first temperature,
The second temperature sensor is Ru second resistor sensor der whose resistance value changes in response to the second temperature,
Fluid level sensing apparatus according to any one of claims 1 to 11. When the liquid level satisfies a specific condition, further comprises an information output unit that outputs information indicating an abnormality,
Fluid level sensing apparatus according to any one of claims 1 to 12. A liquid level detection device according to any one of claims 1 to 13 ,
A compressor including a compression mechanism that compresses a refrigerant and circulates a heat pump, and the container that stores oil for lubricating the compression mechanism as the liquid,
Heat pump system. The liquid level detection device,
Heat pump control means for controlling the heat pump according to the liquid level, further comprising:
The heat pump system according to claim 14 . A first temperature sensor and a second temperature sensor different from the first temperature sensor are arranged inside a container containing a liquid,
After performing the first heat treatment for heating the first temperature sensor, and performing a second heat treatment for heating the first temperature sensor again,
After performing a third heating process of heating the second temperature sensor, performing a fourth heating process of heating the second temperature sensor again,
A first heating time taken until a first temperature is a temperature of the first temperature sensor in said first heat treatment is a temperature difference increases the provision of the first in the second heat treatment a second heating time the temperature required to make the temperature difference increases in the provision, the difference between, or the first rise of the first temperature for a time defined in the first heat treatment is increased Detecting a liquid level of the liquid based on at least one of a value of the first temperature and a second increase value of the first temperature during the predetermined time in the second heat treatment. And
A third heating time required for the second temperature, which is the temperature of the second temperature sensor, to rise by the prescribed temperature difference in the third heating process, and the second heating time in the fourth heating process. And the fourth heating time required until the temperature of the third temperature increases by the specified temperature difference, or the third temperature in which the second temperature is increased during the specified time in the third heat treatment. The liquid level is detected based on at least one of a difference between a rising value of the second temperature and a fourth rising value of the second temperature during the predetermined time in the fourth heat treatment. Do
Liquid level detection method.

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