AIR CONDITIONING SYSTEM

Abstract

A DC power supply (110, 210) generates a supply voltage, which is a DC voltage. A communication circuit (130, 230) can be operated by the supply voltage generated by the DC power supply (110, 210). The communication circuit (130, 230) communicates with another communication circuit (130, 230) using a communication method involving a radio frequency signal via a communication line. The communication line is a core wire (301, 302) enclosed in a cable (300) with a shield (303). The shield (303) is connected at both ends of the cable (300) to an earth connection of the communication circuit (130, 230).

Description

Technical area

[0001] The present disclosure relates to an air conditioning system. background

[0002] Recent sophisticated control and advanced analysis techniques using sampling data have increased communication traffic in air conditioning systems. To respond to this increased communication traffic, the communication method between air conditioning systems can be changed to one that enables high-speed communication. For example, Patent Literature 1 describes an air conditioning system in which an indoor unit and an outdoor unit communicate using a communication method using orthogonal frequency division multiplexing (OFDM).

[0003] When two air conditioning systems have parallel communication lines, crosstalk can occur. This can be caused by capacitive coupling due to stray capacitance between the communication lines or by inductive coupling due to mutual induction. Crosstalk can cause information sent from one air conditioning system to be inadvertently received by another air conditioning system that is not the intended destination. Such crosstalk is more likely to occur with higher-frequency signals used for communication. BibliographyPatent literature

[0004] Patent Literature 1: Unexamined Japanese Patent Application Publication No. 2019-152426 Summary of the inventionTechnical problem

[0005] However, Patent Literature 1 does not describe a technique for reducing such crosstalk. In other words, in the air conditioning system described in Patent Literature 1, crosstalk may occur during communication between air conditioners using radio frequency (RF) signals. Therefore, techniques for reducing crosstalk during communication between air conditioners using RF signals are expected.

[0006] In response to the above problem, an object of the present disclosure is to provide an air conditioning system that reduces crosstalk in communication between air conditioning systems using RF signals. Solution to the task

[0007] To achieve the above-mentioned object, an air conditioning system according to one aspect of the present disclosure includes a plurality of air conditioners and a communication line connecting the plurality of air conditioners. Each of the plurality of air conditioners includes a DC power supply for generating a power supply voltage that is a DC voltage, and a communication circuit operable by the power supply voltage generated by the DC power supply. The communication circuit communicates with another communication circuit by a communication method using a radio frequency signal via the communication line. The communication line is a core wire included in a cable having a shield. The shield is connected to a ground of the communication circuit at two ends of the cable. Advantageous effects of the invention

[0008] In the structure according to the above aspect of the present disclosure, the communication line connecting the plurality of air conditioners is the core wire included in the cable including the shield. The shield is connected to the ground of the communication circuit at both ends of the cable. Thus, the air conditioning system according to the above aspect of the present disclosure can reduce crosstalk in communication between the air conditioners using RF signals. Short description of the drawings Fig. 1 is a block diagram of an air conditioning system according to Embodiment 1; Fig. 2 is a block diagram of an outdoor unit in Embodiment 1; Fig. 3 is a diagram of a refrigerant system in Embodiment 1, illustrating the connections between the devices included in the refrigerant system; Fig. Figure 4 is a diagram of a cable illustrating the connections; Fig. Figure 5 is a diagram describing crosstalk reduction; Fig. 6 is a diagram of a refrigerant system in Embodiment 2, illustrating the connections between the devices included in the refrigerant system; Fig. 7 is a schematic diagram of a DC power supply in Embodiment 3; and Fig. 8 is a schematic diagram of a DC power supply in Embodiment 4. Description of the embodiments

[0009] The embodiments of the present disclosure will be described in detail below with reference to the drawings. In the drawings, like reference numerals denote like or corresponding components. Embodiment 1

[0010] Fig. 1 is a block diagram of an air conditioning system 2000 according to Embodiment 1. The air conditioning system 2000 conditions air within, for example, a building, an apartment building, a residential building, or a factory. The air conditioning system 2000 includes a plurality of refrigerant systems 1000 and a transmission path 40 that interconnects the plurality of refrigerant systems 1000. The air conditioning system 2000 may include any number of refrigerant systems 1000 as needed. In the present embodiment, the air conditioning system 2000 includes at least two refrigerant systems 1000, or more specifically, a refrigerant system 1000A and a refrigerant system 1000B. The refrigerant system 1000A and the refrigerant system 1000B are collectively referred to as refrigerant systems 1000.

[0011] The transmission path 40 enables high-speed baseband communication and is compatible with, for example, Ethernet (registered trademark). The transmission path 40 connects outdoor units 100 included in the multiple refrigerant systems 1000. The communication speed of the baseband communication using the transmission path 40 is, for example, 100 Mbps. The transmission path 40 forms a local area network (LAN).

[0012] Each refrigerant system 1000 is a unit for conditioning indoor air. The refrigerant system 1000 includes an outdoor unit 100, at least one indoor unit 200, and a transfer path 30 connecting the outdoor unit 100 and the indoor unit 200. The refrigerant system 1000 may include any number of indoor units 200 as needed. In the present embodiment, the refrigerant system 1000A includes an outdoor unit 100A, an indoor unit 200A, and a transfer path 30A. The refrigerant system 1000B includes an outdoor unit 100B, an indoor unit 200B, and a transfer path 30B.

[0013] Air conditioners included in the same refrigerant system 1000 are connected to a refrigerant line (not shown) to supply and receive refrigerant from each other. The air conditioners included in the same refrigerant system 1000 are also connected to the transmission path 30 to communicate with each other. The outdoor unit 100A and the outdoor unit 100B are collectively referred to as the outdoor units 100. The indoor unit 200A and the indoor unit 200B are collectively referred to as the indoor units 200. The outdoor units 100 and the indoor units 200 are collectively referred to as the air conditioners. The transmission path 30A and the transmission path 30B are collectively referred to as the transmission paths 30.

[0014] Each outdoor unit 100 is a system installed outdoors for conditioning indoor air. Indoor air conditioning refers to adjusting, for example, the temperature, humidity, and cleanliness of the indoor air. The outdoor unit 100 communicates with the indoor unit 200 via transmission path 30. The outdoor unit 100 circulates a refrigerant between the outdoor unit 100 and the indoor unit 200 through a refrigerant line (not shown). The outdoor unit 100 is an example of an air conditioning system.

[0015] The structure of the outdoor unit 100 will be described with reference to Fig. 2 described. Fig. Figure 2 mainly illustrates components of the outdoor unit 100 used for communication. As shown in Fig. 2, the outdoor unit 100 comprises a control unit 11, a memory 12, a first communicator 13 and a second communicator 14.

[0016] The control unit 11 includes a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and a real-time clock (RCT). The CPU, also called a central processing device, central arithmetic device, processor, microprocessor, microcomputer, or digital signal processor (DSP), functions as a central arithmetic processing unit that performs processing and arithmetic operations to control the outdoor unit 100. In the control unit 11, the CPU reads programs and data stored in the ROM and centrally controls the outdoor unit 100 using the RAM as a work area. The RTC, for example, is an integrated circuit with a clock function. The CPU can determine the current date and time based on the time information read from the RTC.

[0017] Memory 12 includes a non-volatile semiconductor memory, such as a flash memory, an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM), which serves as auxiliary memory. Memory 12 stores programs and data used by control unit 11 to execute various processes. Memory 12 also stores data generated or acquired by control unit 11 through various processes.

[0018] The first communicator 13 communicates with other outdoor units 100 via the transmission path 40, as controlled by the control unit 11. The first communicator 13 includes a communication interface for connecting to the transmission path 40. The first communicator 13 includes, for example, a LAN card compatible with Ethernet (registered trademark).

[0019] The second communicator 14 communicates with the indoor unit 200 via the transmission path 30, as controlled by the control unit 11. The second communicator 14 communicates with the indoor unit 200 via the transmission path 30 using a communication method using radio frequency (RF) signals. For example, the second communicator 14 communicates with the indoor unit 200 using a multi-carrier transmission method. In a multi-carrier transmission method, signals are superimposed on subcarriers with multiple frequency spectra that do not interfere with each other. A typical multi-carrier transmission method is orthogonal frequency division multiplexing (OFDM). The RF signal can have a frequency greater than or equal to 1 MHz. In the present embodiment, the RF signal has a frequency of several to several tens of megahertz. The second communicator 14 includes a communication interface for connecting to the transmission path 30.

[0020] The indoor unit 200 is an indoor air conditioning device installed indoors. The indoor unit 200 supplies conditioned air to indoor spaces. Conditioned air conditions indoor air and is typically heated or cooled air. Heated air heats an indoor space and has a temperature higher than the indoor air temperature. Cooled air cools the indoor space and has a temperature lower than the indoor air temperature.

[0021] The indoor unit 200 includes a control unit (not shown), a memory (not shown), and a communicator (not shown). The control unit has substantially the same structure as the control unit 11. The memory has substantially the same structure as the memory 12. The communicator has substantially the same structure as the second communicator 14. The indoor unit 200 is an example of an air conditioner.

[0022] In each refrigerant system 1000, the transmission path 30 connects the outdoor unit 100 and the indoor unit 200. The transmission path 30 includes a communication line through which the outdoor unit 100 and the indoor unit 200 communicate. For example, if the refrigerant system 1000 includes multiple indoor units 200, the transmission path 30 connects the indoor units 200 in parallel with the outdoor unit 100.

[0023] Transmission path 30A in refrigerant system 1000A and transmission path 30B in refrigerant system 1000B, which are arranged in parallel close to each other, may experience crosstalk, in which a signal from one transmission path 30A propagates to another transmission path 30A. Crosstalk is more likely to occur with the RF signal used for communication at a higher frequency. Crosstalk typically results from, for example, capacitive coupling caused by stray capacitance, inductive coupling caused by mutual induction, or radio wave radiation. Crosstalk in the process of identifying the network configuration can lead to misidentification of the network configuration.

[0024] For example, in the identification process performed in the refrigerant system 1000A, the outdoor unit 100A determines that the indoor unit 200A is included in the refrigerant system 1000A. More specifically, the outdoor unit 100A sends an identification signal via the transmission path 30A. After receiving the identification signal, the indoor unit 200A sends a response signal including the address of the indoor unit 200A to the outdoor unit 100A via the transmission path 30A. The outdoor unit 100A determines that the indoor unit 200A that sent the response signal is included in the refrigerant system 1000A.

[0025] In one example, crosstalk may cause the identification signal to be transmitted to indoor unit 200B via transmission path 30A and transmission path 30B. In this case, indoor unit 200B outputs a response signal including the address of indoor unit 200B to transmission path 30B. Through crosstalk, the response signal may then be transmitted to outdoor unit 100A via transmission path 30B and transmission path 30A. In this case, outdoor unit 100A mistakenly determines that indoor unit 200B, which transmitted the response signal, is included in refrigerant system 100A.

[0026] Therefore, in the present embodiment, a cable including a shield is used as the transmission path 30 to reduce crosstalk. The connections between the devices in the refrigerant system 1000 will be described below with reference to Fig. 3 described.

[0027] The outdoor unit 100 includes a DC power supply 110, a control circuit 120, a communication circuit 130, a terminal block 140, and a metal housing 150. The indoor unit 200 includes a DC power supply 210, a control circuit 220, a communication circuit 230, a terminal block 240, and a metal housing 250. The outdoor unit 100 and the indoor unit 200 are connected to each other via a cable 300. The outdoor unit 100 and the indoor unit 200 are powered by an external power supply 400. In the present embodiment, the external power supply 400 is a commercial power supply that provides a single-phase alternating current (AC) power supply of 200 V. The external power supply 400 is an example of an external power supply.

[0028] The DC power supply 110 generates a DC voltage, which is a power supply voltage, from the power supplied by the external power supply 400. This power supply voltage is used to operate the control circuit 120 and the communication circuit 130. This power supply voltage is Fig. 3 as DC. The DC power supply 110 applies the generated power supply voltage to a power supply terminal 111 and a ground terminal 112. The power supply terminal 111 is a terminal to which the power supply voltage generated by the DC power supply 110 is applied. The ground terminal 112 is a terminal set to a ground potential, which is a reference potential for the operation of the circuit.

[0029] The DC power supply 110 converts the AC power supplied by the external power supply 400 into DC power and outputs the power supply voltage. The DC power supply 110 includes an AC-DC converter (not shown) for converting AC power into DC power. The AC-DC converter (not shown) includes, for example, a diode bridge rectifier (not shown), an input capacitor (not shown), a switching element (not shown), a control circuit (not shown), a fast recovery diode (not shown), and an output capacitor (not shown). The DC power supply 110 is an example of a DC power supply.

[0030] The control circuit 120 controls the communication circuit 130 to perform various communication processes. For example, the control circuit 120 generates a communication command to be transmitted from the communication circuit 130 to the indoor unit 200 and provides the generated communication command to the communication circuit 130. The control circuit 120 also detects a communication command received by the communication circuit 130 from the indoor unit 200 and analyzes the received communication command. The control circuit 120 is powered by the power supplied by the DC power supply 110. In other words, the control circuit 120 is connected to the power supply terminal 111 and the ground terminal 112 and operates with the power supplied via the power supply terminal 111 and the ground terminal 112.The control circuit 120 includes, for example, a CPU (not shown), a ROM (not shown), and a RAM (not shown). The control circuit 120 is associated with the control unit 11.

[0031] The communication circuit 130 communicates with the indoor unit 200 as controlled by the control circuit 120. For example, the communication circuit 130 transmits the communication command generated by the control circuit 120 to the indoor unit 200 via the cable 300. For example, the communication circuit 130 modulates the carrier wave with a baseband signal associated with the communication command to be transmitted and applies the resulting RF signal between two core wires in the cable 300. The RF signal is a differential signal applied between the two core wires. The carrier wave and the RF signal can each have a frequency greater than or equal to 1 MHz. In the present embodiment, the carrier wave and the RF signal each have a frequency of several to several tens of megahertz.

[0032] The communication circuit 130 receives the communication command from the indoor unit 200 via the cable 300 and provides the received communication command to the control circuit 120. For example, the communication circuit 130 demodulates the RF signal applied between the two core wires in the cable 300 and detects the baseband signal corresponding to the received communication command.

[0033] The communication circuit 130 operates with the power supply voltage generated by the DC power supply 110. In other words, the communication circuit 130 is connected to the power supply terminal 111 and the ground terminal 112 and operates with the power supply voltage applied via the power supply terminal 111 and the ground terminal 112. The communication circuit 130 includes, for example, a communication driver integrated circuit (IC) and a communication interface, such as a pulse transformer. The communication circuit 130 belongs to the second communicator 14. The communication circuit 130 is an example of a communication circuit.

[0034] The terminal block 140 connects the cable 300, which serves as the transmission path 30, to the outdoor unit 100. The terminal block 140 includes a terminal 141, a terminal 142 and a terminal 143. The structure and connections of the cable 300 are described below with reference to Fig. 4 described.

[0035] Cable 300 is used, for example, for power supply and communication. Cable 300 is a two-core shielded cable and includes a core wire 301, a core wire 302, a shield 303, an insulator 311, an insulator 312, and an insulator 313. Core wire 301 and core wire 302 each transmit electrical power or electrical signals, for example, and are each made of copper or aluminum, for example.

[0036] The shield 303 serves as a cover and shield for the core wire 301 and the core wire 302. In other words, the shield 303 prevents noise radiated from an outside space from entering the core wire 301 and the core wire 302. The shield 303 also prevents noise from the core wire 301 and the core wire 302 from radiating to the outside space. The shield 303 is formed of copper or aluminum, for example. The insulator 311 serves to cover the core wire 301. The insulator 312 serves to cover the core wire 302. The insulator 313 serves to cover the shield 303. The insulator 311, the insulator 312, and the insulator 313 are each made of, for example, a vinyl chloride resin.

[0037] The core wire 301 has one end connected to terminal 141. The terminal 141 is connected to the communication circuit 130. Thus, the core wire 301 has one end connected to the communication circuit 130. One end of the core wire 302 is connected to the terminal 142. The terminal 142 is connected to the communication circuit 130. Thus, the end of the core wire 302 is connected to the communication circuit 130. One end of the shield 303 is connected to the terminal 143. The terminal 143 is connected to the ground terminal 112.

[0038] The other end of the core wire 301 is connected to a terminal 241. The terminal 241 is connected to the communication circuit 230. Thus, the other end of the core wire 301 is connected to the communication circuit 230. The other end of the core wire 302 is connected to a terminal 242. The terminal 242 is connected to the communication circuit 230. Thus, the other end of the core wire 302 is connected to the communication circuit 230. The other end of the shield 303 is connected to a terminal 243. The terminal 243 is connected to the ground terminal 212.

[0039] Thus, the cable 300 includes a shield, the core wire 301 and the core wire 302 used for communication between the outdoor unit 100 and the indoor unit 200, and the shield 303 for shielding the core wire 301 and the core wire 302. The cable 300 is a cable, such as a vinyl-insulated, vinyl-covered shielded cable for microphones (MVVS) or a vinyl-insulated, vinyl-covered shielded cable for control purposes (CVVS). When the refrigerant system 1000 includes a plurality of indoor units 200, the cable 300 connects the terminal blocks 240 in the plurality of indoor units 200 to each other.

[0040] The metal housing 150 is formed from metal. The metal housing 150 shields the circuits housed therein from the outside. The metal housing 150 houses the control circuit 120, the communication circuit 130, and the terminal block 140. As shown in Fig. 4, the metal housing 150 also houses an uncovered portion 321 at one end of the cable 300. The uncovered portion 321 is a portion at the end of the cable 300 that includes the core wire 301 and the core wire 302 uncovered with the shield 303.

[0041] The metal housing 150 has openings, each of which has a length sufficiently shorter than the wavelength of the RF signal used for communication. In other words, the metal housing 150 does not have any openings longer than a length threshold corresponding to the wavelength of the RF signal used for communication. The length threshold can, for example, be less than or equal to 1 / 100 of the wavelength of the RF signal. The metal housing 150 has various openings through which wires can pass to connect the interior and exterior of the metal housing 150. For each of these openings, the longest section has a length less than or equal to the aforementioned length threshold.

[0042] For example, the metal housing 150 has an opening 151 through which the cable 300 passes. The longest part of the opening 151 has a length less than or equal to the above-mentioned length threshold. As described above, the metal housing 150 has only the opening 151 as an opening, which is sufficiently shorter than the wavelength of the RF signal. Thus, radio waves radiated from the terminal block 140 and the uncovered portion 321 during the transmission of the RF signal are blocked by the metal housing 150. This reduces the crosstalk caused by the radio wave radiation.

[0043] The DC power supply 210 generates the supply voltage, which is a DC voltage, from the power supplied by the external power supply 400. This supply voltage is used to operate the control circuit 220 and the communication circuit 230. The DC power supply 210 applies the generated supply voltage to a power supply terminal 211 and a ground terminal 212. The power supply terminal 211 is a terminal to which the supply voltage generated by the DC power supply 210 is applied. The ground terminal 212 is a terminal set to the ground potential as a reference potential for the operation of the circuit. The DC power supply 210 has substantially the same structure as the DC power supply 110. The DC power supply 210 is an example of the DC power supply.

[0044] The control circuit 220 controls the communication circuit 230 to perform various communication processes. For example, the control circuit 220 generates a communication command to be transmitted from the communication circuit 230 to the outdoor unit 100 and provides the generated communication command to the communication circuit 230. The control circuit 220 also detects a communication command received by the communication circuit 230 from the outdoor unit 100 and analyzes the received communication command. The control circuit 220 is powered by the power supply generated by the DC power supply 210. In other words, the control circuit 220 is connected to the power supply terminal 211 and the ground terminal 212 and operates with the power supply voltage applied via the power supply terminal 211 and the ground terminal 212.The control circuit 220 has essentially the same structure as the control circuit 120.

[0045] The communication circuit 230 communicates with the outdoor unit 100 as controlled by the control circuit 220. For example, the communication circuit 230 transmits the communication command generated by the control circuit 220 to the outdoor unit 100 via the cable 300. For example, the communication circuit 230 modulates the carrier wave with a baseband signal associated with the communication command to be transmitted and applies the resulting RF signal between two core wires in the cable 300.

[0046] The communication circuit 230 receives the communication command from the outdoor unit 100 via the cable 300 and provides the received communication command to the control circuit 220. For example, the communication circuit 230 demodulates the RF signal applied between the two core wires in the cable 300 and detects the baseband signal corresponding to the received communication command.

[0047] The communication circuit 230 operates with the power supply voltage generated by the DC power supply 210. In other words, the communication circuit 230 is connected to the power supply terminal 211 and the ground terminal 212 and operates with the power supply voltage applied via the power supply terminal 211 and the ground terminal 212. The communication circuit 230 has substantially the same structure as the communication circuit 130. The communication circuit 230 is an example of the communication circuit.

[0048] The terminal block 240 connects the cable 300 serving as the transmission path 30 to the indoor unit 200. The terminal block 240 includes the terminal 241, the terminal 242, and the terminal 243. As described above, the other end of the core wire 301 is connected to the communication circuit 230 via the terminal 241. The other end of the core wire 302 is connected to the communication circuit 230 via the terminal 242. The other end of the shield 303 is connected to the ground terminal 212 via the terminal 243.

[0049] The metal housing 250 is formed from metal. The metal housing 250 shields the circuits housed therein from the outside. The metal housing 250 houses the control circuit 220, the communication circuit 230, and the terminal block 240. As shown in Fig. 4, the metal housing 250 also accommodates an uncovered portion 322 at the other end of the cable 300. The uncovered portion 322 is a portion at the other end of the cable 300 in which the core wire 301 and the core wire 302 are not covered with the shield 303.

[0050] The metal housing 250 has no opening longer than the length threshold. The metal housing 250 has various openings through which wires pass to connect the interior and exterior of the metal housing 250. For each of these openings, the longest part has a length less than or equal to the aforementioned length threshold. For example, the metal housing 250 has an opening 251 through which the cable 300 passes. The longest part of the opening 251 has a length less than or equal to the aforementioned length threshold.

[0051] As described above, the metal housing 250 has only the opening 251 as an opening, which is sufficiently shorter than the wavelength of the RF signal. Thus, radio waves radiated from the terminal block 240 and the uncovered part 322 during RF signal transmission are blocked by the metal housing 250. This reduces the crosstalk caused by the radio wave radiation.

[0052] Crosstalk is reduced as described below. Crosstalk results, for example, from capacitive coupling caused by electrostatic induction based on stray capacitance, inductive coupling caused by electromagnetic induction based on mutual induction, or radio wave radiation. Stray capacitance refers to the stray capacitance between the core wire 301 and another core wire or between the core wire 302 and another core wire. Mutual inductance refers to the mutual inductance between the core wire 301 and another core wire or between the core wire 302 and another core wire. Another core wire refers to a core wire that includes the transmission path 30 in another cooling system 1000.

[0053] If the core wire 301 and the core wire 302 are not covered with the shield 303, capacitive coupling may occur between the core wire 301 and another core wire or between the core wire 302 and another core wire during RF signal transmission due to electrostatic induction based on stray capacitance. This may cause the RF signal to be transferred from the core wire 301 or 302 to the other core wire. In addition, electromagnetic induction based on mutual induction may cause inductive coupling between the core wire 301 and another core wire or between the core wire 302 and another core wire. This may also cause the RF signal to be transferred from the core wire 301 or 302 to the other core wire. Radio wave radiation may also cause the RF signal to be transferred from the core wire 301 or 302 to the other core wire.

[0054] In the present embodiment, the core wire 301 and the core wire 302 are covered with the shield 303, and the shield 303 is connected to the ground. Thus, the shield 303, which functions as an electrostatic shield, blocks the electric field during the transmission of the RF signal and reduces the transmission of the RF signal caused by capacitive coupling. The shield 303, which also functions as an electromagnetic shield, blocks the magnetic field during the transmission of the RF signal, thus reducing the transmission of the RF signal caused by inductive coupling. The shield 303, which functions as an electromagnetic shield, also blocks radio waves during the transmission of the RF signal, thus reducing the transmission of the RF signal caused by radio wave radiation.

[0055] The reduction in the transmission of the RF signal due to inductive coupling when the communication circuit 130 in the outdoor unit 100 transmits the RF signal to the communication circuit 230 in the indoor unit 200 will be described below with reference to Fig. 5 described.

[0056] When the communication circuit 130 transmits the RF signal to the communication circuit 230, a transmission current It1 flows in the core wire 301 from the communication circuit 130 to the communication circuit 230. While the transmission current It1 flows in the core wire 301, a noise current In1 is generated in a part of the shield 303 facing the core wire 301. The noise current In1 flows to the ground of the communication circuit 130, which is connected to one end of the shield 303.

[0057] The transmission current It1 flows in the core wire 301 in a direction opposite to the direction in which the noise current In1 flows in the shield 303. Thus, the magnetic field generated by the transmission current It1 and the magnetic field generated by the noise current In1 cancel each other out. This reduces crosstalk caused by inductive coupling between the transmission paths 30. For example, when the outdoor unit 100A transmits the RF signal to the indoor unit 200A via the transmission path 30A, no strong magnetic field is generated in a space outside the transmission path 30A. Thus, no inductive coupling occurs between the transmission path 30A and the transmission path 30B, and no RF signal propagates from the transmission path 30A to the transmission path 30B.

[0058] When the communication circuit 130 transmits the RF signal to the communication circuit 230, a transmission current It2 flows in the core wire 302 from the communication circuit 230 to the communication circuit 130, in addition to the transmission current It1 flowing in the core wire 301 from the communication circuit 130 to the communication circuit 230. The same as described above for the transmission current It1 applies to the transmission current It2. In other words, when the transmission current It2 flows in the core wire 301, a noise current In2 is generated in a part of the shield 303 facing the core wire 302. The noise current In2 flows to the ground of the communication circuit 130, which is connected to one end of the shield 303.

[0059] The transmission current It2 flows in the core wire 302 in a direction opposite to the direction in which the interference current In2 flows in the shield 303. Thus, the magnetic field generated by the transmission current It2 and the magnetic field generated by the interference current In2 cancel each other out. This reduces the crosstalk caused by the inductive coupling between the transmission paths 30.

[0060] In the above example, communication circuit 130 transmits the RF signal to communication circuit 230. The same as described above applies to an example in which communication circuit 230 transmits the RF signal to communication circuit 130. More specifically, a noise current generated by a transmission current flowing from communication circuit 230 to communication circuit 130 flows to ground communication circuit 230, thereby reducing crosstalk caused by inductive coupling between transmission paths 30.

[0061] In the present embodiment, the core wire 301 and the core wire 302 in the cable 300, which includes the shield 303, serve as the communication lines connecting the multiple air conditioners, and the shield 303 is connected to the grounds at both ends of the cable 300. This reduces electrostatic and inductive coupling between the transmission paths 30 and reduces crosstalk to air conditioners not connected to the cable 300. Thus, the structure according to the present embodiment can reduce crosstalk in communication between air conditioners using RF signals.

[0062] In the present embodiment, the metal housing 150, which has no opening longer than the threshold length, accommodates the terminal block 140 and the exposed portion 321 of the cable 300, and the metal housing 250, which has no opening longer than the threshold length, accommodates the terminal block 240 and the exposed portion 322 of the cable 300. The structure according to the present embodiment can reduce crosstalk caused by the radiation of radio waves from the terminal block 140, the terminal block 240, the exposed portion 321, and the exposed portion 322. Embodiment 2

[0063] In Embodiment 1, one end of the shield 303 is directly connected to the ground of the communication circuit 130, and the other end of the shield 303 is directly connected to the ground of the communication circuit 230. In the present embodiment, one end of the shield 303 is indirectly connected to the ground of the communication circuit 130, and the other end of the shield 303 is indirectly connected to the ground of the communication circuit 230. The same components and functions as in Embodiment 1 are not described or are only briefly described.

[0064] As in Fig. As shown in Figure 6, a refrigerant system 1001 according to the present embodiment includes an outdoor unit 101, an indoor unit 201, and the cable 300 serving as the transmission path 30. The outdoor unit 101 includes the DC power supply 110, the control circuit 120, the communication circuit 130, the terminal block 140, the metal casing 150, and a capacitor 160. The indoor unit 201 includes the DC power supply 210, the control circuit 220, the communication circuit 230, the terminal block 240, the metal casing 250, and a capacitor 260.

[0065] Also in the present embodiment, the control circuit 120 and the communication circuit 130 are connected to the power supply terminal 111 and the ground terminal 112 and operate with the power supply voltage applied via the power supply terminal 111 and the ground terminal 112. The control circuit 220 and the communication circuit 230 are connected to the power supply terminal 211 and the ground terminal 212 and operate with the power supply applied via the power supply terminal 211 and the ground terminal 212.

[0066] In the present embodiment, the shield 303 is grounded at two ends of the cable 300. Specifically, one end of the shield 303 is connected to the terminal 143, which is grounded via the metal shell 150 to be grounded. The other end of the shield 303 is connected to the terminal 243, which is grounded via the metal shell 250 to be grounded. When the metal shell 150 and the metal shell 250 are larger, the metal shell 150 and the metal shell 250 do not need to be grounded and can each serve as a ground.

[0067] In the present embodiment, at each of the two ends of cable 300, the impedance between the ground and the earth at an RF signal frequency is less than or equal to a predetermined impedance threshold. The impedance threshold is a value that does not significantly attenuate a signal or noise. In other words, in the present embodiment, a signal or noise of the above frequency can pass between the ground and the earth without significant attenuation.

[0068] In the present embodiment, the ground at each of the two ends of the cable 300 is grounded via a capacitor having a capacitance greater than or equal to a capacitance threshold to connect the ground and the ground with a low impedance at the above frequency. More specifically, at one end of the cable 300, the ground of the communication circuit 130 is grounded via the capacitor 160 having a capacitance greater than or equal to the capacitance threshold. At the other end of the cable 300, the ground of the communication circuit 230 is grounded via the capacitor 260 having a capacitance greater than or equal to the capacitance threshold. The capacitance threshold is a threshold value associated with the frequency of the RF signal described above. The capacitance threshold is larger when the frequency of the RF signal described above is lower. The capacitance threshold is, for example, 1000 pF.

[0069] In the present embodiment, the impedance between one end of the shield 303 and the ground of the communication circuit 130 is low at the above-mentioned frequency. Therefore, a noise current generated by a transmission current flowing from the communication circuit 130 to the communication circuit 230 flows to the ground of the communication circuit 130, thereby reducing crosstalk caused by capacitive coupling, inductive coupling, or radio wave radiation.

[0070] The impedance between the other end of the shield 303 and the ground of the communication circuit 230 at the above frequency is also low. Therefore, a noise current generated by a transmission current flowing from the communication circuit 230 to the communication circuit 130 flows to the ground of the communication circuit 230, thereby reducing crosstalk caused by capacitive coupling, inductive coupling, or radio wave radiation.

[0071] In the present embodiment, the ground of communication circuit 130 and the ground are connected via capacitor 160, and the ground of communication circuit 230 and the ground are connected via capacitor 260. Capacitor 160 and capacitor 260 each function as a Y capacitor. In other words, capacitor 160 causes the common-mode noise generated in cable 300 to flow to the ground to prevent the common-mode noise from flowing to communication circuit 130. Capacitor 260 causes the common-mode noise generated in cable 300 to flow to the ground to prevent the common-mode noise from flowing to communication circuit 230.

[0072] In the present embodiment, as described above, the shield 303 is grounded at both ends of the cable 300, and at each of the two ends of the cable 300, the impedance between the ground and the ground at the frequency of the RF signal is less than or equal to the predetermined impedance threshold. Thus, the structure according to the present embodiment can reduce crosstalk while simultaneously reducing common-mode noise. Embodiment 3

[0073] In Embodiment 1, the noise flowing to other devices via the external power supply 400 is not described. In the present embodiment, a technique for reducing the noise flowing to other devices via the external power supply 400 is described. The noise refers to noise associated with communication using RF signals, such as noise generated in the transmission path 30. The noise is associated with, for example, the noise current In1 or the noise current In2 flowing in the shield 303. The same components and functions as in Embodiments 1 and 2 are not described or are described only briefly.

[0074] As in Fig. 7, a DC power supply 110A in the present embodiment includes the power supply terminal 111, the ground terminal 112, a terminal 113, a terminal 114, an AC-DC converter 115, and a filter circuit 500.

[0075] The power supply terminal 111 is a terminal to which the output power supply voltage 110A is applied. The ground terminal 112 is a terminal to which the ground potential of the power supply 110A is applied. The terminal 113 is connected to one end of the external power supply 400. The terminal 114 is connected to the other end of the external power supply 400. The AC-DC converter 115 converts the AC supplied from the external power supply 400 to DC via the filter circuit 500.

[0076] The filter circuit 500 removes RF waves and is located between the external power supply 400 and the output parts of the DC power supply 110A. The output parts of the DC power supply 110A belong to the power supply terminal 111 and the ground terminal 112. The filter circuit 500 reduces the propagation of RF components from the external power supply 400 to the AC-to-DC converter 115 and reduces the propagation of RF components from the AC-to-DC converter 115 to the external power supply 400. Thus, the filter circuit 500 attenuates the noise flowing from the transmission path 30 via the AC-to-DC converter 115 to the external power supply 400. The filter circuit 500 is an example of a filter circuit.

[0077] The filter circuit 500 includes a terminal 511, a terminal 512, a terminal 513, a terminal 521, a terminal 522, a terminal 523, a resistor 531, a capacitor 532, a common-mode coil 540, a capacitor 551, a capacitor 552, and a capacitor 553. The terminal 511 and the terminal 512 are input terminals. The terminal 521 and the terminal 522 are output terminals. The terminal 513 and the terminal 523 are grounded via the metal housing 150.

[0078] Resistor 531 is a discharge resistor connected between lines. Capacitor 532 and capacitor 551 are each connected between lines, primarily to attenuate normal-mode noise. Capacitor 552 and capacitor 553 are each connected between a line and ground to attenuate common-mode noise.

[0079] The common-mode coil 540 comprises a core made of a magnetic material with copper wires wound around the core in the same phase. This cancels out the magnetic fluxes of the currents flowing in the two coils, creating a large inductance while preventing core saturation. The common-mode coil 540 comprises a coil 541 located on one line and a coil 542 located on another line.

[0080] In the present embodiment, the noise generated during communication using RF signals is attenuated when it passes through the filter circuit 500. Thus, in the present embodiment, the noise flowing to other devices via the external power supply 400 is reduced. The other devices refer to devices connected to the external power supply 400, except for a target device including the DC power supply 110A. For example, if the target device is the outdoor unit 100A, other devices include, for example, the outdoor unit 100B, the indoor unit 200A, and the indoor unit 200B. Embodiment 4

[0081] In Embodiment 3, the filter circuit 500 is located closer to the external power supply 400 than the AC-DC converter 115. In the present embodiment, the AC-DC converter 115 is located closer to the external power supply 400 than the filter circuit 500. The same components and functions as in Embodiments 1 to 3 are not described or are only briefly described.

[0082] As in Fig. 8, the DC power supply 110B in the present embodiment includes the power supply terminal 111, the ground terminal 112, the terminal 113, the terminal 114, the AC-DC converter 115, and the filter circuit 500. In the DC power supply 110B, the AC-DC converter 115 is located closer to the external power supply 400 than the filter circuit 500.

[0083] In other words, the AC-DC converter 115 is connected to terminal 113, terminal 114, terminal 511, and terminal 512, converts the AC power supplied through terminal 113 and terminal 114 into DC power, and supplies the resulting DC power to the filter circuit 500 via terminal 511 and terminal 512. The terminal 521 in the filter circuit 500 and the power supply terminal 111 are connected to each other. The terminal 522 in the filter circuit 500 and the ground terminal 112 are connected to each other. The filter circuit 500 attenuates noise flowing from the transmission path 30 to the external power supply 400 through the AC-DC converter 115.

[0084] In the present embodiment, the noise generated during communication using RF signals is attenuated as it passes through the filter circuit 500. Thus, in the present embodiment, the noise flowing to other devices via the external power supply 400 is reduced. Modifications

[0085] The above-described embodiments of the present disclosure may be modified or applied in various forms to implement the present disclosure. In the present disclosure, the components, functions, and operations described in the above embodiments may be selectively used as needed. In the present disclosure, other components, functions, and operations may also be used in addition to the components, functions, and operations described above. The components, functions, and operations described in the above embodiments may be combined as needed.

[0086] In Embodiment 1, crosstalk is reduced by connecting the shield 303 in the cable 300 to the ground in each of the outdoor unit 100 and the indoor unit 200. In a refrigerant system 1000 including a plurality of indoor units 200, crosstalk can be reduced by connecting the shield 303 in the cable 300 to the ground in each of the plurality of indoor units 200.

[0087] In Embodiment 1, the transmission path 30 is used only for communication. The transmission path 30 can also be used for power supply in addition to communication. For example, the outdoor unit 100 can supply the power supply voltage generated by the DC power supply 110 to the indoor unit 200 via the core wire 301 and the core wire 302 in the cable 300. The indoor unit 200 can supply the voltage generated by the DC power supply 210 to the outdoor unit 100 via the core wire 301 and the core wire 302.

[0088] In Embodiment 1, the outdoor unit 100 and the indoor unit 200 communicate with each other using RF signals for a multi-carrier transmission method. The outdoor unit 100 and the indoor unit 200 may communicate with each other using RF signals for a transmission method other than a multi-carrier transmission method.

[0089] In Embodiment 1, a foil shield is used as the shield 303 in the cable 300. A mesh shield can be used as the shield 303 in the cable 300. In this case, the mesh size can be sufficiently smaller than the wavelength of the RF signal. For example, the mesh size can be less than or equal to the length threshold described above and, for example, 1 / 100 of the wavelength of the RF signal. This reduces the leakage of electric fields, magnetic fields, or radio waves through gaps in the shield 303, thereby reducing crosstalk due to capacitive coupling, inductive coupling, or radio wave radiation.

[0090] In Embodiments 3 and 4, the filter circuit 500 is located inside the power supply 110A or the power supply 110B. The filter circuit 500 may be located outside the power supply 110A or the power supply 110B. In Embodiments 3 and 4, the filter circuit 500 is located near one end of the power supply 110A or the power supply 110B. The filter circuit 500 may be located near both ends of the power supply 110A or both ends of the power supply 110B.

[0091] The filter circuit 500 may be a circuit different from the circuit described in Embodiments 3 and 4. For example, the filter circuit 500 may include the terminal 511, the terminal 512, the terminal 513, the terminal 521, the terminal 522, the terminal 523, and the common-mode coil 540, and may not include the resistor 531, the capacitor 532, the capacitor 551, the capacitor 552, or the capacitor 553.

[0092] The foregoing describes some exemplary embodiments for purposes of explanation. Although specific embodiments have been presented in the foregoing discussion, those skilled in the art will recognize that changes may be made in form and detail without departing from the general spirit and scope of the invention. Accordingly, the DESCRIPTION and drawings are to be regarded in an illustrative rather than a restrictive sense. This detailed description, therefore, is not to be taken in a limiting sense, and the scope of the invention is defined only by the claims to which it belongs, along with the full range of equivalents to which such claims are entitled. Industrial applicability

[0093] The method according to one or more embodiments of the present disclosure is applicable to an air conditioning system comprising an outdoor unit and an indoor unit. List of reference symbols 11 Control unit 12 storage 13 first communicator 14 second communicator 30, 30A, 30B, 40 transmission path 100, 100A, 100B, 101 outdoor unit 110, 110A, 110B, 210 DC power supply 111, 211 power connection 112, 212 113, 114, 141, 142, 143, 241, 242, 243, 511, 512, 513, 521, earth connection 522, 523 connection 115 AC-DC converters 120, 220 control circuit 130, 230 communication circuit 140, 240 terminal block 150, 250 metal housing 151, 251 Opening 160, 260, 532, 551, 552, 553 capacitor 200, 200A, 200B, 201 indoor unit 300 cables 301, 302 core wire 303 Shielding 311, 312, 313 Insulator 321, 322 Uncovered part 400 external power supply 500 filter circuit 531 resistance 540 common mode coil 541, 542 coil 1000, 1000A, 1000B, 1001 refrigerant system 2000 air conditioning system QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2019-152426

[0004]

Claims

[1] An air conditioning system comprising: a variety of air conditioning systems; and a communication line connecting the plurality of air conditioning units, whereby Each of the variety of air conditioning systems includes a DC power supply for generating a power supply voltage which is a DC voltage, and a communication circuit operable with the power supply voltage generated by the DC power supply, the communication circuit communicates with another communication circuit using a communication method using a radio frequency signal via the communication line, the communication line is a core wire contained in a cable with a shield, and the shield at each of two ends of the cable is connected to a ground of the communication circuit. [2] Air conditioning system according to claim 1, wherein the shielding is earthed at both ends of the cable and at each of the two ends of the cable, an impedance between the ground of the communication circuit and an earth at a frequency of the radio frequency signal is less than or equal to a predetermined impedance threshold. [3] The air conditioning system according to claim 2, wherein at each of the two ends of the cable, the ground of the communication circuit is grounded via a capacitor having a capacitance greater than or equal to a capacitance threshold associated with the frequency of the radio frequency signal. [4] An air conditioning system according to any one of claims 1 to 3, wherein each of said plurality of air conditioning units comprises: a terminal block for connecting the communication line to the communication circuit and a metal housing that houses the terminal block and a part of the cable in which the core wire is not covered by the shield, and the metal housing does not have an opening longer than a length threshold corresponding to a wavelength of the radio frequency signal. [5] Air conditioning system according to one of claims 1 to 4, wherein the DC power supply generates the power supply voltage from the power supplied by an external power supply and each of the plurality of air conditioners includes a filter circuit for removing a radio frequency wave between the external power supply and an output portion of the DC power supply. [6] Air conditioning system according to one of claims 1 to 5, wherein the radio frequency signal has a frequency greater than or equal to 1 MHz.

Images