Patent Description:
There has been known a refrigeration system including an indoor unit and an outdoor unit, and configured to cause heat exchange with use of a refrigerant to condition air or execute refrigeration. The refrigeration system needs to execute protection behavior when the refrigerant leaks out of the refrigeration system.

For example, <CIT> discloses determination of whether or not a refrigerant leaks in accordance with a measurement value of a refrigerant detector installed in an indoor unit. Upon determination that the refrigerant leaks, the number of revolutions of an indoor fan may be controlled to be larger than the maximum number of revolutions during normal operation, or a compressor mounted on an outdoor unit may be stopped.

A refrigeration system is also known from <CIT>, <CIT>, and <CIT>.

Conventionally, an indoor control device configured to control an indoor unit and an outdoor control device configured to control an outdoor unit are connected by a transmission line (communication line), to enable transmission and reception of information. The outdoor control device has been conventionally notified of any abnormality of the indoor unit via the transmission line to stop a compressor or the like mounted to the outdoor unit.

In order to enhance safety of a refrigeration system including a plurality of devices (e.g. an indoor unit and an outdoor unit), after abnormality is detected in a first device (e.g. the indoor unit), it is necessary to more quickly notify, of the abnormality, a second device (e.g. the outdoor unit) different from the first device.

It is an object of the present invention to provide a refrigeration system configured to notify abnormality more quickly.

When the protection board is provided separately from the control board, protection behavior can be executed more reliably even when the control board has abnormality.

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

When a first indoor unit <NUM> or a second indoor unit <NUM> comes into an abnormal state in a refrigeration system <NUM> according to an embodiment, a first cable <NUM> and a second cable <NUM> used as communication lines are short-circuited to achieve quicker notification of the abnormal state to a different device (e.g. an outdoor unit <NUM>) connected to the first cable <NUM> and the second cable <NUM>.

<FIG> is a diagram schematically depicting a configuration of the refrigeration system <NUM> according to the embodiment of the present invention.

<FIG> is a diagram schematically depicting an internal configuration of the first indoor unit <NUM> according to the embodiment of the present invention.

<FIG> is a diagram schematically depicting an internal configuration of the second indoor unit <NUM> according to the embodiment of the present invention.

<FIG> is a diagram schematically depicting an internal configuration of the outdoor unit <NUM> according to the embodiment of the present invention.

The refrigeration system <NUM> is configured to cause heat exchange with use of a refrigerant. Examples of the refrigeration system <NUM> include an air conditioner configured to adjust temperature in an indoor space, a refrigeration apparatus configured to refrigerate to store food or the like, and a cold storage apparatus configured to cool to store food and the like. The present embodiment representatively refers to the refrigeration system <NUM> functioning as an air conditioner.

The refrigeration system <NUM> includes the first indoor unit <NUM>, the second indoor unit <NUM>, the outdoor unit <NUM>, a refrigerant pipe <NUM>, the first cable <NUM>, and the second cable <NUM>. The first indoor unit <NUM> exemplifies a "first device " according to the present disclosure. The second indoor unit <NUM> exemplifies a "second device " according to the present disclosure. The outdoor unit <NUM> exemplifies the "second device " according to the present disclosure. The refrigeration system <NUM> may further include an indoor unit other than the first indoor unit <NUM> and the second indoor unit <NUM>.

The first indoor unit <NUM> has a function of adjusting temperature in an indoor space S11. Examples of the first indoor unit <NUM> include an indoor unit of a ceiling embedded type. The first indoor unit <NUM> includes a case <NUM> to be described later, which is disposed in a ceiling space S12 positioned above the indoor space S11. The first indoor unit <NUM> may of a ceiling pendent type, a floorstanding type, or a wall mounted type. In this case, the case <NUM> is disposed in the indoor space S11.

The second indoor unit <NUM> has a function of adjusting temperature in an indoor space S21. The indoor space S21 is positioned in a room different from the indoor space S11. Examples of the second indoor unit <NUM> include an indoor unit of a ceiling embedded type. The second indoor unit <NUM> includes a case <NUM> to be described later, which is disposed in a ceiling space S22 positioned above the indoor space S21. The second indoor unit <NUM> may of a ceiling pendent type, a floorstanding type, or a wall mounted type. In this case, the case <NUM> is disposed in the indoor space S21.

The outdoor unit <NUM> is disposed in an outdoor space S31.

The refrigerant pipe <NUM> allows circulation of a refrigerant. The refrigerant pipe <NUM> connects a heat exchanger <NUM> to be described later in the first indoor unit <NUM>, a heat exchanger <NUM> to be described later in the second indoor unit <NUM>, and a heat exchanger <NUM> to be described later in the outdoor unit <NUM>, to allow the refrigerant to circulate in the heat exchangers <NUM>, <NUM>, and <NUM>.

The first cable <NUM> and the second cable <NUM> electrically connect the first indoor unit <NUM>, the second indoor unit <NUM>, and the outdoor unit <NUM>. Each of the first cable <NUM> and the second cable <NUM> has a function of a communication line communicably connecting the first indoor unit <NUM>, the second indoor unit <NUM>, and the outdoor unit <NUM>.

Specifically, the first indoor unit <NUM> transmits a communication signal to each of the first cable <NUM> and the second cable <NUM> to communicate with the second indoor unit <NUM> and the outdoor unit <NUM>. The second indoor unit <NUM> transmits a communication signal to each of the first cable <NUM> and the second cable <NUM> to communicate with the first indoor unit <NUM> and the outdoor unit <NUM>. The outdoor unit <NUM> transmits a communication signal to each of the first cable <NUM> and the second cable <NUM> to communicate with the first indoor unit <NUM> and the second indoor unit <NUM>.

As depicted in <FIG>, the first cable <NUM> has an outer region <NUM> and three inner regions <NUM>, <NUM>, and <NUM>. The outer region <NUM> has connection among first terminals <NUM>, <NUM>, and <NUM> to be described later. The three inner regions <NUM>, <NUM>, and <NUM> have connection between the first terminals <NUM>, <NUM>, and <NUM> and control boards <NUM>, <NUM>, and <NUM> to be described later.

As depicted in <FIG>, the second cable <NUM> has an outer region <NUM> and three inner regions <NUM>, <NUM>, and <NUM>. The outer region <NUM> has connection among second terminals <NUM>, <NUM>, and <NUM> to be described later. The three inner regions <NUM>, <NUM>, and <NUM> have connection between the second terminals <NUM>, <NUM>, and <NUM> and the control boards <NUM>, <NUM>, and <NUM> to be described later.

The present embodiment provides two cables (the first cable <NUM> and the second cable <NUM>) serving as communication lines. There may alternatively be provided three or more cables as communication lines. In this case, appropriate two out of the three or more cables will be referred to as the first cable <NUM> and the second cable <NUM>.

The first indoor unit <NUM> includes an operation unit <NUM>, a control board <NUM>, a protection board <NUM>, a terminal block <NUM>, the case <NUM>, a remote controller <NUM>, and a sensor <NUM>. The case <NUM> accommodates part of the operation unit <NUM>, the control board <NUM>, the protection board <NUM>, and the terminal block <NUM>.

The remote controller <NUM> and the sensor <NUM> are disposed outside the case <NUM>. The remote controller <NUM> and the sensor <NUM> are disposed in the indoor space S11 in the present embodiment. Alternatively, the sensor <NUM> may be disposed in the ceiling space S12 or in the case <NUM>.

The remote controller <NUM> is wiredly or wirelessly connected to the control board <NUM> and the protection board <NUM>. The remote controller <NUM> includes a display unit <NUM> and an input unit <NUM>. The display unit <NUM> includes an LED, a liquid crystal panel, and the like. The display unit <NUM> displays, to a user, states (e.g. current set temperature, airflow volume, airflow direction, details of an error occurring in the refrigeration system <NUM>) of the refrigeration system <NUM> in accordance with a command from a control unit <NUM> or a control circuit <NUM> to be described later. The input unit <NUM> includes a button operated by a user to set temperature, airflow volume, airflow direction, or the like. Upon receipt of input by a user, the input unit <NUM> transmits the input to the control board <NUM> or the protection board <NUM>.

The operation unit <NUM> includes a fan <NUM>, a heat exchanger <NUM>, a display unit <NUM>, a first ventilator (not depicted), and a first shutoff valve (not depicted). The case <NUM> accommodates the fan <NUM> and the heat exchanger <NUM>. The case <NUM> accommodates the display unit <NUM> in a state where a user of the indoor space S11 can see display. The first ventilator and the first shutoff valve are disposed outside the case <NUM>.

The fan <NUM> imports air in the indoor space S11 into the case <NUM>, and supplies the indoor space S11 with air (conditioned air) obtained through heat exchange caused by the heat exchanger <NUM> in the case <NUM>. The heat exchanger <NUM> is exemplarily of a cross-fin tube type. The heat exchanger <NUM> is connected with the refrigerant pipe <NUM>.

The display unit <NUM> includes an LED, a liquid crystal panel, and the like, and is configured to display the states of the refrigeration system <NUM> to a user. For example, the display unit <NUM> may light a green LED in order to indicate normal operation, or may flicker a yellow LED in order to indicate an error of the refrigeration system <NUM>. The display unit <NUM> may further display a state of the first indoor unit <NUM> in the liquid crystal panel.

The first ventilator (not depicted) is configured to discharge air in the indoor space S11 into the outdoor space S31, and includes a fan. The first ventilator is exemplarily provided on a wall separating the indoor space S11 and the outdoor space S31.

The first shutoff valve (not depicted) is configured to control circulation in the refrigerant pipe <NUM> upstream of the heat exchanger <NUM> or the like. The first shutoff valve is opened constantly, and allow the refrigerant to flow into the heat exchanger <NUM> via the refrigerant pipe <NUM>. When the first shutoff valve closes, the heat exchanger <NUM> is separated from the refrigerant pipe <NUM> to stop a flow of the refrigerant from the refrigerant pipe <NUM> into the first indoor unit <NUM>. The first shutoff valve is provided in the ceiling space S12 or the like.

The terminal block <NUM> is a component connecting the first cable <NUM> and the second cable <NUM> to each component in the case <NUM>. The terminal block <NUM> includes the first terminal <NUM> and the second terminal <NUM>. The first terminal <NUM> is connected with the first cable <NUM>. The second terminal <NUM> is connected with the second cable <NUM>.

The control board <NUM> is configured to control normal behavior of the first indoor unit <NUM>, and includes the control unit <NUM> and a communication unit <NUM>. The control board <NUM> is equipped with an arithmetic device such as a microprocessor, and a storage device such as a memory IC. Each of the control unit <NUM> and the communication unit <NUM> is embodied when the arithmetic device reads a program preliminarily stored in the storage device.

The control board <NUM> is connected with the first cable <NUM> and the second cable <NUM>. Specifically, the first cable <NUM> (the inner region <NUM>) is connected between the first terminal <NUM> and the control board <NUM>, and the second cable <NUM> (the inner region <NUM>) is connected between the second terminal <NUM> and the control board <NUM>. The communication unit <NUM> receives communication signals flowing in the first cable <NUM> and the second cable <NUM>.

The control unit <NUM> controls behavior of the operation unit <NUM> in accordance with the preliminarily stored program and information inputted through the communication unit <NUM>. The control unit <NUM> controls the number of revolutions of the fan <NUM>, display on the display unit <NUM>, and the like. The control unit <NUM> also controls display on the display unit <NUM> of the remote controller <NUM>.

The communication unit <NUM> communicates with a different device (e.g. the second indoor unit <NUM> or the outdoor unit <NUM>) included in the refrigeration system <NUM>. The communication unit <NUM> converts a communication signal constituted by a potential difference between the first cable <NUM> and the second cable <NUM> to a digital signal, and transmits, to the control unit <NUM>, the digital signal as information inputted through a different device. The communication unit <NUM> further converts the digital signal outputted from the control unit <NUM> to a communication signal and transmits the communication signal to the first cable <NUM> and the second cable <NUM>.

The protection board <NUM> is provided separately from the control board <NUM>, and is configured to control behavior for protection of the first indoor unit <NUM>. The protection board <NUM> includes the first circuit <NUM> and a fourth circuit <NUM>. Each of the first circuit <NUM> and the fourth circuit <NUM> does not include any arithmetic device such as a microprocessor, and is constituted only by hardware.

The first circuit <NUM> is configured to short-circuit the first cable <NUM> and the second cable <NUM> upon detection of abnormality in the first indoor unit <NUM>. The first circuit <NUM> includes an abnormality detection circuit <NUM>, and a short circuit <NUM>.

The abnormality detection circuit <NUM> is configured to detect abnormality relevant to refrigerant leakage. The abnormality detection circuit <NUM> is electrically connected to the sensor <NUM>, the short circuit <NUM>, and the control circuit <NUM>. The abnormality detection circuit <NUM> detects abnormality relevant to refrigerant leakage in accordance with a detection signal of the sensor <NUM>. The sensor <NUM> will be described later in terms of its configuration.

Examples of abnormality relevant to refrigerant leakage include refrigerant leakage from the refrigerant pipe <NUM>, trouble of the sensor <NUM> configured to detect refrigerant leakage, and a life cycle of the sensor <NUM>. The abnormality detection circuit <NUM> detecting abnormality relevant to refrigerant leakage transmits a predetermined electric signal to each of the short circuit <NUM> and control circuit <NUM>.

The short circuit <NUM> includes a cable <NUM>, a cable <NUM>, and a switch <NUM>. The cable <NUM> has a first end connected to the first terminal <NUM>, and a second end connected to a first side of the switch <NUM>. The first end of the cable <NUM> may alternatively be connected the inner region <NUM> of the first cable <NUM>. The cable <NUM> has a first end connected to the second terminal <NUM>, and a second end connected to a second side of the switch <NUM>. The first end of the cable <NUM> may alternatively be connected the inner region <NUM> of the second cable <NUM>. In such a configuration, the switch <NUM> is connected parallelly to the first cable <NUM> and the second cable <NUM> via the cable <NUM> and the cable <NUM>.

The switch <NUM> is constantly in an opened state. When the abnormality detection circuit <NUM> detects abnormality relevant to refrigerant leakage, a predetermined electric signal is transmitted from the abnormality detection circuit <NUM> to the short circuit <NUM>. The switch <NUM> is turned from the opened state into a connected state in accordance with the predetermined electric signal. The first cable <NUM> and the second cable <NUM> are thus electrically connected to each other via the cable <NUM>, the switch <NUM>, and the cable <NUM> by electrical resistance lower than a normal level (the first cable <NUM> and the second cable <NUM> are short-circuited by the short circuit <NUM>).

Each of the cable <NUM> and the cable <NUM> may include a resistive element having low resistance. Also in such a configuration, the first cable <NUM> and the second cable <NUM> are short-circuited when the switch <NUM> is turned into the connected state. The present disclosure refers to "short-circuit" including a case where the first cable <NUM> and the second cable <NUM> are electrically connected by electrical resistance substantially equal to zero, and a case where the first cable <NUM> and the second cable <NUM> are electrically connected via the resistive element having low resistance. In any one of the cases, large current, which does not flow upon normal communication, flows between the first cable <NUM> and the second cable <NUM>.

The fourth circuit <NUM> is configured to start protection behavior for the first indoor unit <NUM> when the first cable <NUM> and the second cable <NUM> are short-circuited. The fourth circuit <NUM> includes a short-circuit detection circuit <NUM>, and a control circuit <NUM>.

The short-circuit detection circuit <NUM> is configured to detect short-circuit between the first cable <NUM> and the second cable <NUM>. The short-circuit detection circuit <NUM> has a first end connected to the cable <NUM> and a second end connected to the cable <NUM>. Alternatively in the short-circuit detection circuit <NUM>, the first end may be connected to the inner region <NUM> of the first cable <NUM> and the second end may be connected to the inner region <NUM> of the second cable <NUM>. Furthermore, the short-circuit detection circuit <NUM> is electrically connected to the control circuit <NUM>.

The short-circuit detection circuit <NUM> is exemplarily configured to detect a potential difference between the first cable <NUM> and the second cable <NUM>. When the potential difference is less than a predetermined lower limit value continuously for a predetermined time period (e.g. longer than a <NUM> V output time period of a normal communication signal), the short-circuit detection circuit <NUM> assumes that the first cable <NUM> and the second cable <NUM> are short-circuited and transmits a predetermined electric signal to the control circuit <NUM>.

The short-circuit detection circuit <NUM> may alternatively be configured to detect a current value of at least one of the first cable <NUM> and the second cable <NUM> (as an overcurrent detection circuit). In this case, the short-circuit detection circuit <NUM> includes a current sensor inserted to at least one of the first cable <NUM> and the second cable <NUM>. When the current sensor detects a current value exceeding a predetermined upper limit value, the short-circuit detection circuit <NUM> assumes that the first cable <NUM> and the second cable <NUM> are short-circuited and transmits a predetermined electric signal to the control circuit <NUM>.

The control circuit <NUM> is electrically connected to the operation unit <NUM>. When the short-circuit detection circuit <NUM> detects short-circuit between the first cable <NUM> and the second cable <NUM>, a predetermined electric signal is transmitted from the short-circuit detection circuit <NUM> to the control circuit <NUM>. When the control circuit <NUM> receives the predetermined electric signal, the control circuit <NUM> controls the operation unit <NUM>, and causes the operation unit <NUM> to execute protection behavior against abnormality.

The protection behavior to be executed by the operation unit <NUM> includes abnormality inhibiting behavior and abnormality notifying behavior. The abnormality inhibiting behavior includes behavior for recovering the refrigeration system <NUM> from an abnormal state to a normal state or preventing further deterioration of the abnormal state of the refrigeration system <NUM>. The abnormality notifying behavior includes behavior for notifying a user of abnormality of the refrigeration system <NUM>.

The abnormality inhibiting behavior includes rotating the fan <NUM> so as to have the maximum number of revolutions. The abnormality inhibiting behavior further includes operating the first ventilator (not depicted) so as to have the maximum airflow volume. Such behavior causes any leaked refrigerant to spread quickly so as to prevent local increase in refrigerant concentration. Rotation of the fan <NUM> or behavior of the first ventilator may be continued for a preset time period or the like, or may be continued until the abnormality detection circuit <NUM> detects no more abnormality.

When the abnormality inhibiting behavior includes rotation of the fan <NUM> or behavior of the first ventilator, the abnormality inhibiting behavior may further include stopping reception of any input from the input unit <NUM> of the remote controller <NUM>. In this case, any input to the input unit <NUM> will not be transmitted to the control unit <NUM>. This behavior avoids a situation where other protection behavior such as rotating the fan <NUM> is stopped earlier before the preset time period elapses.

When stopping reception of any input from the input unit <NUM>, the display unit <NUM> of the remote controller <NUM> may display "unable to input" or the like when a user presses the button of the input unit <NUM> in order to notify the user that the input is invalid.

The abnormality inhibiting behavior includes closing the first shutoff valve (not depicted) provided on the refrigerant pipe <NUM>. Such behavior stops the flow of the refrigerant from the refrigerant pipe <NUM> into the first indoor unit <NUM>, for inhibition of further refrigerant leakage.

The abnormality notifying behavior includes display of refrigerant leakage on the display unit <NUM> by means of light or sound. In this case, the LED in the display unit <NUM> may be flickered in a color (e.g. yellow or red) different from a color during normal operation, the liquid crystal panel in the display unit <NUM> may display refrigerant leakage by means of letters, or a speaker included in the display unit <NUM> may output alert sound.

The abnormality notifying behavior includes display of refrigerant leakage on the display unit <NUM> of the remote controller <NUM> by means of light or sound. Such behavior can achieve notification of refrigerant leakage to a user.

The sensor <NUM> is configured to detect refrigerant leakage. The sensor <NUM> is electrically connected to the abnormality detection circuit <NUM>. The sensor <NUM> is configured to detect refrigerant concentration or the like, and transmits the refrigerant concentration thus detected as a detection signal to the abnormality detection circuit <NUM>. For example, the detection signal of the sensor <NUM> exceeding a predetermined upper limit value indicates that the refrigerant leaks to exceed prescribed concentration. When the abnormality detection circuit <NUM> receives such a detection signal exceeding the predetermined upper limit value from the sensor <NUM>, the abnormality detection circuit <NUM> detects abnormality of refrigerant leakage.

The detection signal of the sensor <NUM> less than a predetermined lower limit value (e.g. the value of the detection signal of the sensor <NUM> is zero) continuously for a predetermined time period indicates that the sensor <NUM> is in trouble and does not have correct output. When the abnormality detection circuit <NUM> receives such a detection signal less than the predetermined lower limit value from the sensor <NUM> (or receives no detection signal), the abnormality detection circuit <NUM> detects trouble of the sensor <NUM>.

The sensor <NUM> may be configured to directly detect refrigerant concentration, or may be configured to indirectly detect refrigerant concentration. Examples of the sensor <NUM> configured to indirectly detect refrigerant concentration include a carbon dioxide sensor and an oxygen concentration sensor. Upon refrigerant leakage, gas normally contained in the air has concentration relatively decreased due to increase in refrigerant concentration in the air. Decrease in concentration of the gas normally contained in the air is detected by the sensor <NUM>, to achieve indirect detection of increase in refrigerant concentration.

When the sensor <NUM> is configured to detect oxygen concentration, the sensor <NUM> transmits the oxygen concentration thus detected as a detection signal to the abnormality detection circuit <NUM>. For example, the detection signal of the sensor <NUM> less than the predetermined lower limit value indicates that oxygen is less than prescribed concentration, so that it is estimated that the refrigerant leaks to exceed the prescribed concentration. When the abnormality detection circuit <NUM> receives such a detection signal less than the predetermined lower limit value from the sensor <NUM> (oxygen concentration sensor), the abnormality detection circuit <NUM> detects abnormality of refrigerant leakage.

The sensor <NUM> may alternatively be a pressure sensor provided on the refrigerant pipe <NUM>. The sensor <NUM> detects refrigerant pressure in the refrigerant pipe <NUM>, and transmits the pressure thus detected as a detection signal to the abnormality detection circuit <NUM>. Refrigerant pressure in the refrigerant pipe <NUM> decreases upon refrigerant leakage. In an exemplary case where the detection signal of the sensor <NUM> is less than the predetermined lower limit value, the abnormality detection circuit <NUM> detects abnormality of refrigerant leakage assuming that a refrigerant exceeding predetermined volume leaks from the refrigerant pipe <NUM>.

The abnormality detection circuit <NUM> may optionally be provided therein with a counter. The counter is configured to count an electrification time period between the sensor <NUM> and the abnormality detection circuit <NUM>, and record an integrated value of the electrification time period. When the integrated value exceeds a predetermined upper limit value, the abnormality detection circuit <NUM> detects abnormality assuming that the sensor <NUM> has reached the life cycle due to aged deterioration. The predetermined upper limit value may be set shorter than the actual life cycle of the sensor <NUM> due to aged deterioration for safety. When the aged sensor <NUM> is replaced with a new sensor <NUM>, the integrated value of the electrification time period is reset on the counter of the abnormality detection circuit <NUM>.

The second indoor unit <NUM> includes an operation unit <NUM>, a control board <NUM>, a protection board <NUM>, a terminal block <NUM>, the case <NUM>, a remote controller <NUM>, and a sensor <NUM>. These components are configured similarly to the operation unit <NUM>, the control board <NUM>, the protection board <NUM>, the terminal block <NUM>, the case <NUM>, the remote controller <NUM>, and the sensor <NUM> in the first indoor unit <NUM>. The second indoor unit <NUM> will not be described repeatedly where appropriate in terms of components configured similarly to the components of the first indoor unit <NUM>.

The remote controller <NUM> and the sensor <NUM> are disposed in the indoor space S21 in the present embodiment. Alternatively, the sensor <NUM> may be disposed in the ceiling space S22 or in the case <NUM>.

The remote controller <NUM> includes a display unit <NUM> and an input unit <NUM>. The display unit <NUM> and the input unit <NUM> are configured similarly to the display unit <NUM> and the input unit <NUM>, respectively.

The operation unit <NUM> includes a fan <NUM>, a heat exchanger <NUM>, a display unit <NUM>, a second ventilator (not depicted), and a second shutoff valve (not depicted). These components are configured similarly to the fan <NUM>, the heat exchanger <NUM>, the display unit <NUM>, the first ventilator (not depicted), and the first shutoff valve (not depicted).

The fan <NUM> imports air in the indoor space S21 into the case <NUM>, and supplies the indoor space S21 with air (conditioned air) obtained through heat exchange caused by the heat exchanger <NUM> in the case <NUM>. The second ventilator (not depicted) is configured to discharge air in the indoor space S21 into the outdoor space S31, and includes a fan. The second ventilator is exemplarily provided on a wall separating the indoor space S21 and the outdoor space S31. The second shutoff valve is provided in the ceiling space S22 or the like.

The terminal block <NUM> includes the first terminal <NUM> and the second terminal <NUM>. These components are configured similarly to the first terminal <NUM> and the second terminal <NUM>.

The control board <NUM> is configured to control normal behavior of the second indoor unit <NUM>, and includes a control unit <NUM> and a communication unit <NUM>. These components are configured similarly to the control unit <NUM> and the communication unit <NUM>. The control board <NUM> is connected with the first cable <NUM> and the second cable <NUM>. Specifically, the first cable <NUM> (the inner region <NUM>) is connected between the first terminal <NUM> and the control board <NUM>, and the second cable <NUM> (the inner region <NUM>) is connected between the second terminal <NUM> and the control board <NUM>. The communication unit <NUM> communicates with a different device (e.g. the first indoor unit <NUM> or the outdoor unit <NUM>) included in the refrigeration system <NUM>.

The protection board <NUM> includes a third circuit <NUM> and a second circuit <NUM>. Each of the third circuit <NUM> and the second circuit <NUM> is constituted only by hardware. The third circuit <NUM> is configured similarly to the first circuit <NUM>, and the second circuit <NUM> is configured similarly to the fourth circuit <NUM>.

The third circuit <NUM> includes an abnormality detection circuit <NUM>, and a short circuit <NUM>. The short circuit <NUM> includes a cable <NUM>, a cable <NUM>, and a switch <NUM>. These components are configured similarly to the abnormality detection circuit <NUM>, the short circuit <NUM>, the cable <NUM>, the cable <NUM>, and the switch <NUM>.

The second circuit <NUM> is configured to start protection behavior for the second indoor unit <NUM> when the first cable <NUM> and the second cable <NUM> are short-circuited. The second circuit <NUM> includes a short-circuit detection circuit <NUM>, and a control circuit <NUM>. These components are configured similarly to the short-circuit detection circuit <NUM> and the control circuit <NUM>.

The outdoor unit <NUM> includes an operation unit <NUM>, a control board <NUM>, a protection board <NUM>, a terminal block <NUM>, and a case <NUM>. These components are configured similarly to the operation unit <NUM>, the control board <NUM>, the protection board <NUM>, the terminal block <NUM>, and the case <NUM> in the first indoor unit <NUM>. The outdoor unit <NUM> will not be described repeatedly where appropriate in terms of components configured similarly to the components of the first indoor unit <NUM>.

The operation unit <NUM> includes a fan <NUM>, a heat exchanger <NUM>, and a third shutoff valve (not depicted). These components are configured similarly to the fan <NUM>, the heat exchanger <NUM>, and the first shutoff valve (not depicted). The operation unit <NUM> further includes a compressor <NUM> configured to compress a refrigerant. The compressor <NUM> is connected to the refrigerant pipe <NUM>.

The fan <NUM> imports air in the outdoor space S31 into the case <NUM>, and discharges, to the outdoor space S31, air obtained through heat exchange caused by the heat exchanger <NUM> in the case <NUM>. The third shutoff valve is provided in the case <NUM> or the like.

The control board <NUM> is configured to control normal behavior of the outdoor unit <NUM>, and includes a control unit <NUM> and a communication unit <NUM>. These components are configured similarly to the control unit <NUM> and the communication unit <NUM>. The control board <NUM> is connected with the first cable <NUM> and the second cable <NUM>. Specifically, the first cable <NUM> (the inner region <NUM>) is connected between the first terminal <NUM> and the control board <NUM>, and the second cable <NUM> (the inner region <NUM>) is connected between the second terminal <NUM> and the control board <NUM>. The communication unit <NUM> communicates with a different device (e.g. the first indoor unit <NUM> or the second indoor unit <NUM>) included in the refrigeration system <NUM>.

The protection board <NUM> includes a second circuit <NUM>. The second circuit <NUM> is constituted only by hardware. The second circuit <NUM> is configured similarly to the fourth circuit <NUM>.

The second circuit <NUM> is configured to start protection behavior for the outdoor unit <NUM> when the first cable <NUM> and the second cable <NUM> are short-circuited. The second circuit <NUM> includes a short-circuit detection circuit <NUM>, and a control circuit <NUM>.

The short-circuit detection circuit <NUM> is configured to detect short-circuit between the first cable <NUM> and the second cable <NUM>. The short-circuit detection circuit <NUM> has a first end connected to the inner region <NUM> and a second end connected to the inner region <NUM>. Furthermore, the short-circuit detection circuit <NUM> is electrically connected to the control circuit <NUM>.

The short-circuit detection circuit <NUM> is exemplarily configured to detect a potential difference between the first cable <NUM> and the second cable <NUM>. When the potential difference is less than a predetermined lower limit value continuously for a predetermined time period, the short-circuit detection circuit <NUM> assumes that the first cable <NUM> and the second cable <NUM> are short-circuited and transmits a predetermined electric signal to the control circuit <NUM>.

The short-circuit detection circuit <NUM> may alternatively be configured to detect a current value of at least one of the first cable <NUM> and the second cable <NUM> (as an overcurrent detection circuit). When the current value exceeds a predetermined upper limit value, the short-circuit detection circuit <NUM> assumes that the first cable <NUM> and the second cable <NUM> are short-circuited and transmits a predetermined electric signal to the control circuit <NUM>.

The protection behavior to be executed by the operation unit <NUM> includes abnormality inhibiting behavior. The abnormality inhibiting behavior includes behavior for recovering the refrigeration system <NUM> from an abnormal state to a normal state or preventing further deterioration of the abnormal state of the refrigeration system <NUM>.

The abnormality inhibiting behavior includes stopping the compressor <NUM>. The abnormality inhibiting behavior further includes closing the third shutoff valve (not depicted). Such behavior stops refrigerant circulation in the refrigerant pipe <NUM>, for inhibition of further refrigerant leakage.

The abnormality inhibiting behavior further includes interlocking the outdoor unit <NUM> after stopping the compressor <NUM> and closing the third shutoff valve. In this case, the compressor <NUM> is not activated and the third shutoff valve is not opened in the outdoor unit <NUM> unless a predetermined input condition is satisfied. Such behavior prevents unintended restart of the compressor <NUM> and the like during continuation of the abnormal state such as refrigerant leakage.

Described with appropriate reference to <FIG> is a protection method in the refrigeration system <NUM>.

<FIG> is a flowchart exemplifying a protection method in the refrigeration system <NUM>.

Initially described is behavior of the first indoor unit <NUM>.

Assume an exemplary case where the refrigerant leaks from a portion of the refrigerant pipe <NUM> connected with the first indoor unit <NUM> (e.g. a joint of the pipe) into the ceiling space S12 and the indoor space S11. In this case, the sensor <NUM> initially detects the refrigerant and transmits a detection signal to the abnormality detection circuit <NUM>. When the detection signal exceeds the predetermined upper limit value, the abnormality detection circuit <NUM> detects abnormality relevant to refrigerant leakage assuming that the refrigerant leaks to exceed the prescribed concentration, and transmits a predetermined electric signal to the short circuit <NUM> and the control circuit <NUM> (abnormality detection step ST <NUM>).

The switch <NUM> is turned from the opened state into the connected state when the short circuit <NUM> receives the predetermined electric signal from the abnormality detection circuit <NUM>. This leads to short-circuit between the first cable <NUM> and the second cable <NUM> (short-circuiting step ST22).

The short-circuit detection circuit <NUM> subsequently detects short-circuit between the first cable <NUM> and the second cable <NUM>, and transmits a predetermined electric signal to the control circuit <NUM> (short-circuit detection step ST23).

When the control circuit <NUM> receives the predetermined electric signal, the control circuit <NUM> causes the operation unit <NUM> to execute protection behavior against abnormality (protection behavior step ST24).

The control circuit <NUM> may cause the operation unit <NUM> to execute protection behavior against abnormality at any earlier timing when receiving the predetermined electric signal from the abnormality detection circuit <NUM> or when receiving the predetermined electric signal from the short-circuit detection circuit <NUM>. Such a configuration enables execution of protection behavior step ST24 readily after abnormality detection step ST21 in the first indoor unit <NUM> having abnormality. Accordingly, short-circuit step ST22 and short-circuit detection step ST23 can be skipped for quicker start of protection behavior against abnormality.

Described next is behavior of the second indoor unit <NUM>.

The second indoor unit <NUM> is connected to the first cable <NUM> and the second cable <NUM>. If the first cable <NUM> and the second cable <NUM> are short-circuited at first time t1 in short-circuit step ST22, the short-circuit detection circuit <NUM> in the second indoor unit <NUM> detects short-circuit between the first cable <NUM> and the second cable <NUM> at second time t2 after the first time t1, and transmits a predetermined electric signal to the control circuit <NUM> (short-circuit detection step ST31).

When the control circuit <NUM> receives the predetermined electric signal, the control circuit <NUM> causes the operation unit <NUM> to execute protection behavior against abnormality (protection behavior step ST32).

Described next is behavior of the outdoor unit <NUM>.

The outdoor unit <NUM> is connected to the first cable <NUM> and the second cable <NUM>. If the first cable <NUM> and the second cable <NUM> are short-circuited at the first time t1 in short-circuit step ST22, the short-circuit detection circuit <NUM> in the outdoor unit <NUM> detects short-circuit between the first cable <NUM> and the second cable <NUM> at the second time t2 after the first time t1, and transmits a predetermined electric signal to the control circuit <NUM> (short-circuit detection step ST41).

When the control circuit <NUM> receives the predetermined electric signal, the control circuit <NUM> causes the operation unit <NUM> to execute protection behavior against abnormality (protection behavior step ST42).

Described hereinafter is a conventional protection method. When abnormality relevant to refrigerant leakage occurs and the first indoor unit <NUM> detects the abnormality, the first indoor unit <NUM> conventionally transmits a communication signal to the first cable <NUM> and the second cable <NUM> serving as communication lines, to notify the second indoor unit <NUM> and the outdoor unit <NUM> of the abnormality.

More specifically, when abnormality such as refrigerant leakage is detected in the first indoor unit <NUM>, the abnormality detection circuit <NUM> transmits, to the control unit <NUM>, an electric signal for abnormality notification. The control unit <NUM> generates a predetermined digital signal (e.g. an error code) for abnormality notification to a different device (e.g. each of the second indoor unit <NUM> and the outdoor unit <NUM>), and transmits the digital signal to the communication unit <NUM>. The communication unit <NUM> converts the digital signal to a communication signal and transmits the communication signal to the first cable <NUM> and the second cable <NUM>.

In the second indoor unit <NUM>, the communication unit <NUM> converts the communication signal received from each of the first cable <NUM> and the second cable <NUM> to a digital signal, and transmits, to the control unit <NUM>, the digital signal thus converted. The control unit <NUM> analyzes the digital signal thus received, to determine a type of the error (refrigerant leakage in this exemplary case) and cause the operation unit <NUM> to execute protection behavior.

As described above, according to the conventional protection method, abnormality is notified from the abnormality detection circuit <NUM> in the first indoor unit <NUM> to the control unit <NUM> in the second indoor unit <NUM> via the control unit <NUM>, the communication unit <NUM>, the first cable <NUM> and the second cable <NUM>, and the communication unit <NUM> in the mentioned order. Accordingly, both a device having detected abnormality (e.g. the first indoor unit <NUM>) and a device notified of abnormality (e.g. the second indoor unit <NUM>) need processing (signal generation or analysis) in the control units <NUM> and <NUM> and signal conversion in the communication units <NUM> and <NUM>. Such processing includes calculation in the arithmetic device such as a microprocessor, so that abnormality notification from one device to another device takes a time period like about one minute.

In contrast, in the refrigeration system <NUM> according to the present embodiment, the first indoor unit <NUM> includes the short circuit <NUM> that short-circuits the first cable <NUM> and the second cable <NUM> serving as communication lines when the abnormality detection circuit <NUM> detects abnormality. When the short-circuit detection circuits <NUM> and <NUM> in the second indoor unit <NUM> and the outdoor unit <NUM> detects short-circuit, the control circuits <NUM> and <NUM> cause the operation units <NUM> and <NUM> to execute protection behavior.

Such a series of behavior does not include calculation such as generation of an error code or conversion of a communication signal. Abnormality is notified in accordance with a simple standard regarding whether or not there is a predetermined electric signal. It accordingly shortens, to <NUM> seconds or less, the time period from abnormality detection by the abnormality detection circuit <NUM> in the first indoor unit <NUM> to start of protection behavior by the operation units <NUM> and <NUM>, enabling quicker abnormality notification than the conventional case.

In the refrigeration system <NUM>, the protection board <NUM> is provided separately from the control board <NUM>. Such a configuration enables more reliable protection behavior even when the control board <NUM> has any abnormality. The control unit <NUM> of the control board <NUM> may be configured to be communicable with each component (e.g. the control circuit <NUM>) of the protection board <NUM>. In this case, the control board <NUM> and the protection board <NUM> are provided separately from each other. When the protection board <NUM> has any abnormality, the control board <NUM> can thus detect the abnormality of the protection board <NUM> in accordance with incommunicability with the protection board <NUM>. When the control board <NUM> detects abnormality of the protection board <NUM>, the control unit <NUM> causes the operation unit <NUM> to execute protection behavior, and notifies a different device (e.g. the second indoor unit <NUM>) of the abnormality via the communication unit <NUM>.

Provision of the control board <NUM> and the protection board <NUM> separately from each other enables protection behavior by the operation unit <NUM> and abnormality notification to a different device even if any of the control board <NUM> and the protection board <NUM> has abnormality. This enhances reliability of protection behavior and abnormality notification in the refrigeration system <NUM>.

<FIG> is a flowchart exemplifying a protection method in the refrigeration system <NUM> according to a modification example.

<FIG> relates to a case where the first indoor unit <NUM> detects abnormality. <FIG> relates to a case where the second indoor unit <NUM> detects abnormality.

Initially described is behavior of the second indoor unit <NUM>.

Assume an exemplary case where the refrigerant leaks from a portion of the refrigerant pipe <NUM> connected with the second indoor unit <NUM> (e.g. a joint of the pipe) into the ceiling space S22 and the indoor space S21. In this case, the sensor <NUM> initially detects the refrigerant and transmits a detection signal to the abnormality detection circuit <NUM>. When the detection signal exceeds the predetermined upper limit value, the abnormality detection circuit <NUM> detects abnormality of the second indoor unit <NUM> assuming that the refrigerant leaks to exceed the prescribed concentration, and transmits a predetermined electric signal to the short circuit <NUM> and the control circuit <NUM> (abnormality detection step ST <NUM>).

The switch <NUM> is turned from the opened state into the connected state when the short circuit <NUM> receives the predetermined electric signal from the abnormality detection circuit <NUM>. This leads to short-circuit between the first cable <NUM> and the second cable <NUM> (short-circuiting step ST34).

The short-circuit detection circuit <NUM> subsequently detects short-circuit between the first cable <NUM> and the second cable <NUM>, and transmits a predetermined electric signal to the control circuit <NUM> (short-circuit detection step ST35).

When the control circuit <NUM> receives the predetermined electric signal, the control circuit <NUM> causes the operation unit <NUM> to execute protection behavior against abnormality (protection behavior step ST36).

The control circuit <NUM> may cause the operation unit <NUM> to execute protection behavior against abnormality at any earlier timing when receiving the predetermined electric signal from the abnormality detection circuit <NUM> or when receiving the predetermined electric signal from the short-circuit detection circuit <NUM>. Such a configuration enables execution of protection behavior step ST36 readily after abnormality detection step ST33 in the second indoor unit <NUM> having abnormality. Accordingly, short-circuit step ST34 and short-circuit detection step ST35 can be skipped for quicker start of protection behavior against abnormality.

Described next is behavior of the first indoor unit <NUM>.

The first indoor unit <NUM> is connected to the first cable <NUM> and the second cable <NUM>. If the first cable <NUM> and the second cable <NUM> are short-circuited at first time t3 in short-circuit step ST34, the short-circuit detection circuit <NUM> in the first indoor unit <NUM> detects short-circuit between the first cable <NUM> and the second cable <NUM> at second time t4 after the first time t3, and transmits a predetermined electric signal to the control circuit <NUM> (short-circuit detection step ST31).

When the control circuit <NUM> receives the predetermined electric signal, the control circuit <NUM> causes the operation unit <NUM> to execute protection behavior against abnormality (protection behavior step ST25).

The outdoor unit <NUM> is connected to the first cable <NUM> and the second cable <NUM>. If the first cable <NUM> and the second cable <NUM> are short-circuited at the first time t3 in short-circuit step ST34, the short-circuit detection circuit <NUM> in the outdoor unit <NUM> detects short-circuit between the first cable <NUM> and the second cable <NUM> at the second time t4 after the first time t3, and transmits a predetermined electric signal to the control circuit <NUM> (short-circuit detection step ST43).

When the control circuit <NUM> receives the predetermined electric signal, the control circuit <NUM> causes the operation unit <NUM> to execute protection behavior against abnormality (protection behavior step ST44.

As described above, even when the second indoor unit <NUM> has abnormality, the first indoor unit <NUM> and the outdoor unit <NUM> can be notified of abnormality more quickly by short-circuiting the first cable <NUM> and the second cable <NUM> serving as communication lines.

The protection board <NUM> in the outdoor unit <NUM> according to the above embodiment includes the second circuit <NUM> configured to cause the operation unit <NUM> to execute protection behavior upon detection of short-circuit. The protection board <NUM> may further include a third circuit <NUM> configured to short-circuit the first cable <NUM> and the second cable <NUM> upon detection of abnormality.

<FIG> is a diagram schematically depicting an outdoor unit 40a according to a modification example. The outdoor unit 40a is different from the outdoor unit <NUM> according to the above embodiment in that the outdoor unit 40a includes the third circuit <NUM> and a sensor <NUM>. The sensor <NUM> is configured similarly to the sensors <NUM> and <NUM>, and is exemplarily configured to detect concentration of a refrigerant leaking in the outdoor unit 40a. The third circuit <NUM> includes an abnormality detection circuit <NUM>, and a short circuit <NUM>.

The abnormality detection circuit <NUM> is configured similarly to the abnormality detection circuits <NUM> and <NUM>, and is electrically connected to the sensor <NUM>. When the abnormality detection circuit <NUM> detects any abnormality of the outdoor unit 40a in accordance with a detection signal of the sensor <NUM>, the abnormality detection circuit <NUM> transmits a predetermined electric signal to each of the short circuit <NUM> and control circuit <NUM>.

The short circuit <NUM> is configured similarly to the short-circuits <NUM> and <NUM>, and includes cables <NUM> and <NUM>, and a switch <NUM>. The cables <NUM> and <NUM> are connected to the first terminal <NUM> and the second terminal <NUM>, respectively. The switch <NUM> is turned from the opened state into the connected state when the short circuit <NUM> receives the predetermined electric signal from the abnormality detection circuit <NUM>. This leads to short-circuit of the first cable <NUM> and the second cable <NUM>.

Such a configuration enables quicker notification of abnormality in the outdoor unit 40a to the first indoor unit <NUM> and the second indoor unit <NUM>. In this case, the outdoor unit 40a may function as the "first device" according to the present disclosure.

<FIG> is a diagram schematically depicting a configuration of a refrigeration system 10a according to a modification example. When the first indoor unit <NUM> comes into the abnormal state in the refrigeration system 10a, the first cable <NUM> and the second cable <NUM> used as communication lines are short-circuited to achieve quicker notification of the abnormal state to a different device (e.g. the remote controller <NUM>) connected to the first cable <NUM> and the second cable <NUM>.

The refrigeration system 10a includes the first indoor unit <NUM>, the second indoor unit <NUM>, the outdoor unit <NUM> (not depicted in <FIG>), the refrigerant pipe <NUM> (not depicted in <FIG>), the first cable <NUM>, the second cable <NUM>, and a plurality of remote controllers 80a, 80b, and 80c. Each of the remote controllers 80a, 80b, and 80c will be simply called the "remote controller <NUM>" when the remote controllers 80a, 80b, and 80c are not particularly distinguished from one another. According to the present modification example, the first indoor unit <NUM> exemplifies the "first device", and the remote controller <NUM> exemplifies the "second device".

The remote controllers 80a and 80b are wiredly connected to the indoor units <NUM> and <NUM> one by one. Specifically, the remote controller 80a is communicably connected to the first indoor unit <NUM> via an outer region <NUM> of the first cable <NUM> and an outer region <NUM> of the second cable <NUM>. The remote controller 80b is communicably connected to the second indoor unit <NUM> via the outer region <NUM> of the first cable <NUM> and the outer region <NUM> of the second cable <NUM>. For example, the remote controller 80a is disposed in the indoor space S11 (<FIG>), and the second remote controller 80b is disposed in the indoor space S21 (<FIG>).

The single remote controller 80c is multiply and wiredly connected to the plurality of indoor units <NUM> and <NUM>, and is also referred to as a centralized control device. Specifically, the remote controller 80c is communicably connected to the first indoor unit <NUM> and the second indoor unit <NUM> via an outer region <NUM> of the first cable <NUM> and an outer region <NUM> of the second cable <NUM>. For example, the remote controller 80c is disposed in a space (e.g. a machine chamber) different from the indoor space S11 and the indoor space S21.

<FIG> is a diagram schematically depicting an internal configuration of the remote controller 80a. The remote controller 80a includes a control board <NUM>, a protection board <NUM>, a terminal block <NUM>, a case <NUM>, and a sensor <NUM>. These components are configured similarly to the control board <NUM>, the protection board <NUM>, the terminal block <NUM>, the case <NUM>, and the sensor <NUM> in the first indoor unit <NUM>. The remote controller 80a will not be described repeatedly where appropriate in terms of components configured similarly to the components of the first indoor unit <NUM>.

The remote controller 80a further includes an operation unit <NUM>. The operation unit <NUM> includes a display unit <NUM> configured to display various contents to a user, and an input unit <NUM> configured to receive input from a user. The display unit <NUM> includes a display and a speaker, and displays various contents in accordance with a command from a control unit <NUM> and a control circuit <NUM> to be described later. The input unit <NUM> receives input for control of the first indoor unit <NUM>. For example, the input unit <NUM> includes a button operated by a user to set temperature, airflow volume, airflow direction, or the like. Upon receipt of input by a user, the input unit <NUM> transmits the input to the control unit <NUM> to be described later.

The control board <NUM> is configured to control normal behavior of the remote controller 80a, and includes the control unit <NUM> and a communication unit <NUM>. These components are configured similarly to the control unit <NUM> and the communication unit <NUM>. The control board <NUM> is connected with the first cable <NUM> and the second cable <NUM>. Specifically, the first cable <NUM> (an inner region <NUM>) is connected between a first terminal <NUM> and the control board <NUM>, and the second cable <NUM> (an inner region <NUM>) is connected between a second terminal <NUM> and the control board <NUM>. The communication unit <NUM> communicates with a different device (e.g. the first indoor unit <NUM>) included in the refrigeration system 10a.

The second circuit <NUM> is configured to start protection behavior for the remote controller 80a when the first cable <NUM> and the second cable <NUM> are short-circuited. The second circuit <NUM> includes a short-circuit detection circuit <NUM>, and the control circuit <NUM>. These components are configured similarly to the short-circuit detection circuit <NUM> and the control circuit <NUM>.

When the short-circuit detection circuit <NUM> detects short-circuit between the first cable <NUM> and the second cable <NUM> and the control circuit <NUM> receives the predetermined electric signal, the control circuit <NUM> controls the operation unit <NUM> to execute protection behavior against abnormality. The protection behavior to be executed by the operation unit <NUM> includes abnormality notifying behavior. The abnormality notifying behavior according to the present modification example includes display of refrigerant leakage on the display unit <NUM> by means of light or sound. Such behavior can achieve notification of refrigerant leakage to a user.

The terminal block <NUM> includes the first terminal <NUM> and the second terminal <NUM>. These components are configured similarly to the first terminal <NUM> and the second terminal <NUM>. The outer region <NUM> of the first cable <NUM> electrically connects the first terminal <NUM> and the first terminal <NUM> (<FIG>), and the outer region <NUM> of the second cable <NUM> electrically connects the second terminal <NUM> and the second terminal <NUM> (<FIG>).

The remote controller 80b is different from the remote controller 80a in that the remote controller 80b includes the input unit <NUM> for control of the second indoor unit <NUM>. The remaining components are configured similarly to the components of the remote controller 80a and will thus not be described repeatedly.

The remote controller 80c includes the input unit <NUM> for control of the first indoor unit <NUM> and the second indoor unit <NUM>. The remote controller 80c does not include the third circuit <NUM> or the sensor <NUM>, and the short-circuit detection circuit <NUM> is electrically connected to the inner region <NUM> and the inner region <NUM>. The remote controller 80c is different from the remote controller 80a in these points. The remaining components are configured similarly to the components of the remote controller 80a and will thus not be described repeatedly.

Description is made next to behavior of the refrigeration system 10a. When the abnormality detection circuit <NUM> detects any abnormality in accordance with a detection signal of the sensor <NUM> in the first indoor unit <NUM> (<FIG>), the short circuit <NUM> short-circuits the first cable <NUM> and the second cable <NUM>. This leads to short-circuit of the outer region <NUM> and the outer region <NUM>. This also leads to short-circuit of the outer region <NUM> and the outer region <NUM>. Accordingly, the short-circuit detection circuit <NUM> in the remote controller <NUM> detects short-circuit, and the control circuit <NUM> causes the operation unit <NUM> to execute protection behavior. For example, the display unit <NUM> generates buzzer sound in order to notify a user of abnormality relevant to refrigerant leakage.

As described above, when the first indoor unit <NUM> (exemplifying the first device) detects abnormality relevant to refrigerant leakage, the remote controller <NUM> (exemplifying the second device) detects the abnormality by detecting short-circuit of the first cable <NUM> and the second cable <NUM>, for quicker protection behavior.

The remote controller <NUM> may alternatively detect abnormality relevant to refrigerant leakage in the present modification example. Specifically, when the abnormality detection circuit <NUM> detects abnormality in accordance with a detection signal of the sensor <NUM> in the remote controller 80a, the short circuit <NUM> short-circuits the first cable <NUM> and the second cable <NUM>. Accordingly, the short-circuit detection circuit <NUM> in the first indoor unit <NUM> detects short-circuit, and the control circuit <NUM> causes the operation unit <NUM> to execute protection behavior.

In this case, the remote controller <NUM> functions as the "first device", the third circuit <NUM> functions as the "first circuit", and the second circuit <NUM> functions as the "fourth circuit" according to the present disclosure. The first indoor unit <NUM> functions as the "second device", and the first circuit <NUM> functions as the "third circuit" according to the present disclosure. In this manner, the remote controller <NUM> and the first indoor unit <NUM> have both the function as the "first device" and the function as the "second device" according to the present disclosure.

According to the above modification example, the remote controller 80c (centralized control device) is communicably connected to the first indoor unit <NUM> and the second indoor unit <NUM> via the first cable <NUM> and the second cable <NUM>. However, the remote controller 80c should not be limited thereto in terms of its connection mode. For example, the remote controller 80c may alternatively be communicably connected to a plurality of outdoor units <NUM> (e.g. a first outdoor unit <NUM> and a second outdoor unit <NUM>) via the first cable <NUM> and the second cable <NUM>. In this case, if abnormality relevant to refrigerant leakage is detected in the first outdoor unit <NUM> and the first cable <NUM> and the second cable <NUM> are short-circuited, the remote controller 80c detects short-circuit of the first cable <NUM> and the second cable <NUM>, and causes the operation unit <NUM> to execute protection behavior.

The refrigerant pipe <NUM> according to the above embodiment causes refrigerant circulation to both the first device (e.g. the first indoor unit <NUM>) and the second device (e.g. the second indoor unit <NUM>). However, the refrigerant pipe <NUM> does not necessarily need to cause refrigerant circulation to both the first device and the second device, and may alternatively cause refrigerant circulation only in the first device or the second device.

For example, in the refrigeration system 10a (<FIG>) according to the modification example, the refrigerant pipe <NUM> is not connected with the remote controller <NUM>. In an exemplary case where the remote controller <NUM> functions as the second device, the refrigerant pipe <NUM> accordingly needs to cause refrigerant circulation only in the first device (e.g. the first indoor unit <NUM>), without need to cause refrigerant circulation to both the first device and the second device.

<FIG> is a diagram schematically depicting the first cable <NUM> and the second cable <NUM> according to a modification example.

According to the above embodiment, the first indoor unit <NUM> (exemplifying the first device), the second indoor unit <NUM> (exemplifying the second device), and the outdoor unit <NUM> (exemplifying the second device) are directly connected via the first cable <NUM> and the second cable <NUM>, without insertion of any other device. However, the first cable <NUM> and the second cable <NUM> have only to electrically connect the first indoor unit <NUM>, the second indoor unit <NUM>, and the outdoor unit <NUM>, without need to directly connect the first indoor unit <NUM>, the second indoor unit <NUM>, and the outdoor unit <NUM>.

For example, the first indoor unit <NUM> and the second indoor unit <NUM> may interpose a device D1 (e.g. an amplifier circuit) as depicted in <FIG>, to divide the first cable <NUM> into two cables in a first region 61a and a second region 61b, and divide the second cable <NUM> to two cables in a first region 71a and a second region 71b.

The first indoor unit <NUM>, the second indoor unit <NUM>, and the outdoor unit <NUM> may interpose a device D2 (e.g. a branching circuit) therebetween as depicted in <FIG>, to branch the first cable <NUM> and the second cable <NUM>. In this case, the first cable <NUM> may be divided into three cables in a first region 61c connecting from the device D1 to the first indoor unit <NUM>, a second region 61d connecting from the device D2 to the second indoor unit <NUM>, and a third region 61e connecting from the device D2 to the outdoor unit <NUM>. The second cable <NUM> may be divided into three cables in a first region 71c connecting from the device D2 to the first indoor unit <NUM>, a second region 71d connecting from the device D2 to the second indoor unit <NUM>, and a third region 71e connecting from the device D2 to the outdoor unit <NUM>.

Furthermore, the first cable <NUM> and the second cable <NUM> have only to have two poles, without need to be physically divided into two cables. For example, the first cable <NUM> and the second cable <NUM> may be collectively provided as a single cable.

The protection board <NUM> according to the above embodiment includes the first circuit <NUM> and the fourth circuit <NUM>. Alternatively, the protection board <NUM> may not include the fourth circuit <NUM>. In this case, the abnormality detection circuit <NUM> in the first circuit <NUM> may be electrically connected to the control unit <NUM>, so as to transmit a predetermined electric signal to the control unit <NUM> upon abnormality detection.

The protection board <NUM> according to the above embodiment is accommodated in the case <NUM>. The protection board <NUM> may alternatively be disposed outside the case <NUM>. In this case, the protection board <NUM> may be accommodated in a second case (not denoted) provided separately from the case <NUM> and disposed in the ceiling space S12. The second case may accommodate, in addition to the protection board <NUM>, the sensor <NUM> or the like. Similarly, the protection boards <NUM> and <NUM> may alternatively be disposed outside the cases <NUM> and <NUM>, respectively.

The control circuit <NUM> may alternatively determine contents of protection behavior in accordance with whether or not the control circuit <NUM> receives a predetermined electric signal from the abnormality detection circuit <NUM>. For example, when the control circuit <NUM> receives the predetermined electric signal from each of the short-circuit detection circuit <NUM> and the abnormality detection circuit <NUM>, the first indoor unit <NUM> itself has abnormality. Accordingly, the control circuit <NUM> executes protection behavior including both abnormality inhibiting behavior (e.g. rotating the fan <NUM> to have the maximum number of revolutions), and abnormality notifying behavior (e.g. flickering the LED on the display unit <NUM>).

In a different exemplary case where the control circuit <NUM> receives a predetermined electric signal from the short-circuit detection circuit <NUM> but does not receive any predetermined electric signal from the abnormality detection circuit <NUM>, the second indoor unit <NUM> has abnormality whereas the first indoor unit <NUM> itself has no abnormality. When the first indoor unit <NUM> and the second indoor unit <NUM> are disposed in different chambers as in the above embodiment, abnormality inhibiting behavior is not highly necessary in the first indoor unit <NUM> even if the second indoor unit <NUM> has refrigerant leakage. Furthermore, a user may feel uncomfortable with abnormality inhibiting behavior of rotating the fan <NUM> to have the maximum number of revolutions in the first indoor unit <NUM> or the like.

If the control circuit <NUM> receives the predetermined electric signal from the short-circuit detection circuit <NUM> but does not receive any predetermined electric signal from the abnormality detection circuit <NUM>, the control circuit <NUM> may thus cause the operation unit <NUM> to execute only abnormality notifying behavior without executing abnormality inhibiting behavior.

In the refrigeration system <NUM> thus configured, protection behavior including both abnormality inhibiting behavior and abnormality notifying behavior can be executed in a device having abnormality (e.g. the second indoor unit <NUM>), whereas protection behavior including only abnormality notifying behavior can be executed in a device having no abnormality (e.g. the first indoor unit <NUM>). This can inhibit a user of the first indoor unit <NUM> from feeling uncomfortable as well as can more quickly notify the user of abnormality of the refrigeration system <NUM>. The outdoor unit <NUM> may execute abnormality inhibiting behavior even if the outdoor unit <NUM> itself does not have any abnormality.

The refrigerant pipe <NUM> according to the above embodiment directly connects the first indoor unit <NUM> and the second indoor unit <NUM>. However, the refrigerant pipe <NUM> has only to function to cause refrigerant circulation to the first indoor unit <NUM> and the second indoor unit <NUM>, and the refrigerant pipe <NUM> may not directly connect the first indoor unit <NUM> and the second indoor unit <NUM>. For example, the first indoor unit <NUM> and the second indoor unit <NUM> may interpose different indoor unit (or outdoor unit) or a branching unit configured to branch the refrigerant pipe <NUM>, so that the refrigerant pipe <NUM> is connected to the first indoor unit <NUM> and the second indoor unit <NUM> via the different indoor unit or the like. In this case, the refrigerant pipe <NUM> is not provided between the first indoor unit <NUM> and the second indoor unit <NUM>. However, the refrigerant pipe <NUM> can cause refrigerant circulation to the first indoor unit <NUM> and the second indoor unit <NUM> via the different indoor unit. Similarly, the refrigerant pipe <NUM> has only to function to cause refrigerant circulation to the first indoor unit <NUM> and the outdoor unit <NUM>, and the refrigerant pipe <NUM> may not directly connect the first indoor unit <NUM> and the outdoor unit <NUM>.

At least parts of the embodiments described above may be appropriately combined with each other.

When the protection board <NUM>, <NUM> is provided separately from the control board <NUM>, <NUM>, protection behavior can be executed more reliably even when the control board <NUM>, <NUM> has any abnormality.

Claim 1:
A refrigeration system (<NUM>, 10a) comprising:
a first device (<NUM>, <NUM>);
a second device (<NUM>, <NUM>, <NUM>, <NUM>) communicably connected to the first device (<NUM>, <NUM>) via a first cable (<NUM>) and a second cable (<NUM>); and
a refrigerant pipe (<NUM>) configured to cause refrigerant circulation to the first device (<NUM>, <NUM>) or the second device (<NUM>, <NUM>, <NUM>, <NUM>), wherein
the first device (<NUM>, <NUM>) includes a first circuit (<NUM>, <NUM>) configured to short-circuit the first cable (<NUM>) and the second cable (<NUM>) upon detection of abnormality relevant to refrigerant leakage, and
the second device (<NUM>, <NUM>, <NUM>, <NUM>) includes a second circuit (<NUM>, <NUM>, <NUM>, <NUM>) configured to start protection behavior against abnormality when the first cable (<NUM>) and the second cable (<NUM>) are short-circuited.