JP2007282318A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air conditioner which can surely cut off energization to an inverter when a high-voltage switch is in operation by using a relay contact, without imposing a burden on the relay contact, and thereby can extend the life of a relay. <P>SOLUTION: When the high-voltage switch 20 is operated and released, the drive of the inverter 4 is stopped. After the drive is stopped, the constantly opened contact 31a of the relay 31 in an energization passage to the inverter 4 is released. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an air conditioner including a high pressure switch that operates in accordance with a high pressure of a refrigeration cycle.

  In an air conditioner equipped with a compressor, an outdoor heat exchanger, a decompressor, a refrigeration cycle that circulates refrigerant by connecting piping, and an inverter that outputs driving power to the compressor motor, A high-pressure switch connected to an AC power supply is attached to the high-pressure side piping of the cycle, and a relay contact that is de-energized in accordance with the operation of the high-voltage switch is inserted into the energization path to the inverter (for example, patent) Reference 1).

That is, when the high pressure of the refrigeration cycle rises abnormally and the high pressure switch operates, the energization to the relay is interrupted, the relay contact is opened, and the energization to the inverter is interrupted. Thereby, the operation of the compressor is stopped, and the piping and equipment of the refrigeration cycle are protected.
Japanese Patent Laid-Open No. 3-5673

  A large current required for the operation of the compressor flows through the current path to the inverter. When the high pressure is abnormally increased, the energization path through which the large current flows is suddenly interrupted by the relay contact, which places a heavy burden on the relay contact. This adversely affects the life of the relay.

  For this reason, it is conceivable to detect the operation of the high-voltage switch and stop driving the inverter before the relay is opened. However, since the high-voltage switch is connected to the AC power supply, the relay is opened and the AC power supply is zero-crossed. You have to distinguish the difference. For this reason, a certain amount of time is required to detect the operation of the high-voltage switch, and it is difficult to stop the drive of the inverter before the relay is opened.

  Also, there is a method in which the high voltage switch is connected to a DC power source, the operation of the high voltage switch is detected by the control circuit and the drive of the inverter is stopped, and then the relay inserted in the current path from the control circuit to the inverter is disconnected. However, if the control circuit fails, there is a possibility that the relay will not be disconnected even if the high-voltage switch operates.

  In view of the above, the present invention takes the above-mentioned circumstances into consideration, and can cut off the energization to the inverter at the time of the high-voltage switch operation reliably by the relay contact and can be executed without imposing a burden on the relay contact. Thus, an object of the present invention is to provide an air conditioner that can improve the life of the relay.

  The invention according to claim 1 includes a compressor, an outdoor heat exchanger, a decompressor, a refrigeration cycle that pipes the indoor heat exchanger and circulates the refrigerant, and is connected to a commercial AC power source, and drives the motor of the compressor An inverter that outputs electric power, an inrush current limiting resistance element that is inserted into a current path between the commercial AC power source and the inverter, a normally open contact that is connected in parallel with the resistance element, and a DC drive A relay having a coil, switch means inserted in the energizing path for the coil of the relay, and a high pressure inserted in the energizing path for the coil of the relay and operating and opening when the high pressure of the refrigeration cycle rises abnormally A switch, detection means for detecting the operation of the high-voltage switch, turning on the switch means with a predetermined time delay from turning on the commercial AC power, and driving the inverter As well as start, during operation detection of the detection means, and a control means for stopping the driving of the inverter.

  According to the air conditioner of the present invention, it is possible to cut off the energization to the inverter during the operation of the high pressure switch with the relay contact and without imposing a burden on the relay contact. Therefore, energization can be reliably interrupted during the operation of the high-voltage switch, and the life of the relay can be improved.

  [1] A first embodiment of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, a reactor 2 is inserted into a current path from a commercial AC power supply 1 to an inverter 4, and a resistance element for limiting an inrush current, such as a positive temperature coefficient thermistor (hereinafter referred to as PTC) 3, is inserted. Has been. The PTC 3 limits the current so that an inrush current does not flow through the inverter 4 when the commercial AC power supply 1 is turned on.

  The inverter 4 includes a rectifier circuit 5 that rectifies the voltage of the commercial AC power supply 1 and a switching circuit 6 that converts an output voltage (DC voltage) of the rectifier circuit 5 into an AC voltage having a predetermined frequency by switching. . The output of the inverter 4 is supplied as drive power to the compressor motor 10 connected to the terminal 7.

  The compressor motor 10 is accommodated in the compressor 11. A four-way valve 12, an outdoor heat exchanger 13, an expansion valve 14, and an indoor heat exchanger 15 are sequentially connected to the compressor 11 by piping to constitute a refrigeration cycle. That is, at the time of cooling, the refrigerant discharged from the compressor 11 flows in the direction of the solid line arrow, the outdoor heat exchanger 13 functions as a condenser, and the indoor heat exchanger 15 functions as an evaporator. During heating, the four-way valve 12 is switched so that the refrigerant discharged from the compressor 11 flows in the direction of the wavy arrow in the figure, the outdoor heat exchanger 15 functions as a condenser, and the outdoor heat exchanger 13 functions as an evaporator. .

  A normally closed high pressure switch 20 is attached to the high pressure side pipe of the refrigeration cycle. The high pressure switch 20 operates and opens when the high pressure at a predetermined location in the refrigeration cycle abnormally increases.

  On the other hand, a DC power supply circuit 8 is connected to the commercial AC power supply 1. The DC power supply circuit 8 outputs a DC voltage 5V and a DC voltage 12V necessary for the operation of the control circuit. One end of the coil 31c of the relay 31 is connected to the positive terminal to which the DC voltage 12V is applied via the high voltage switch 20, and the other end of the coil 31c is connected between the collector and the emitter of the NPN transistor 33, for example. Grounded. In other words, the high voltage switch 20 and the collector and emitter of the transistor 33 are inserted into the current path of the DC voltage 12V to the coil 31c of the relay 31.

  The relay 31 includes a normally open contact 31a and a DC-driven coil 31c. A normally open contact 31a of the relay 31 is connected in parallel to the PTC 3. A freewheeling diode D is connected between the two ends of the coil 31c so as to be in a direction opposite to the DC voltage.

  A DC voltage of 5 V is applied between the base and emitter of the transistor 33 via a resistor 34, and the collector and emitter of an NPN transistor 35 are connected between the base and emitter of the transistor 33. The base of the transistor 35 is connected to the MCU 40 via the resistor 36.

  In addition, an operation detection circuit 29 including a series circuit of resistors 37 and 38 is connected to an energization path between the high-voltage switch 20 and the coil 31 c of the relay 31. The operation detection circuit 29 outputs a voltage generated in the resistor 38, outputs a voltage of a predetermined level (logic “1” signal) when the high-voltage switch 20 is not operating, and the high-voltage switch 20 operates to be opened. In this case, the output becomes zero (logic “0” signal).

  The MCU 40 operates with a DC voltage of 5 V applied via the resistor 41. A data storage memory (EEPROM) 42 is connected to the MCU 40. The MCU 40 includes main control means for driving and controlling the inverter 4, relay control means for driving and controlling the relay 31, and detection means for detecting the operation of the high-voltage switch 20 from the output of the operation detection circuit 29.

Among these, the main control means and the relay control means have the control means (1) and (2) based on mutual linkage.
(1) Control means for turning on the transistor 33 and starting driving the inverter 4 with a predetermined time (several seconds) delay after the commercial AC power supply 1 is turned on (= application of a DC voltage of 5 V).
(2) Control means for stopping the drive of the inverter 4 when detecting the operation of the detection means.

The operation will be described.
When the commercial AC power source 1 is turned on (operation start), a current flows from the commercial AC power source 1 through the PTC 3 to the inverter 4. In this case, the current flowing by the resistance of the PTC 3 is limited, and an excessive inrush current does not flow to the inverter 4.

  The MCU 40 turns on the transistor 35 when the commercial AC power supply 1 is turned on. When the transistor 35 is turned on, the transistor 33 is turned off, and the energization path for the coil 31c of the relay 31 is interrupted. Thus, energization through the PTC 3 is performed as described above by keeping the normally open contact 31a of the relay 31 open.

  A few seconds after the commercial AC power supply 1 is turned on, the MCU 40 turns off the transistor 35 and drives the inverter 4. When the transistor 35 is turned off, the transistor 33 is turned on, and an energization path for the coil 31c of the relay 31 is formed. Thereby, the normally open contact 31a of the relay 31 is closed.

  When the normally open contact 31a is closed, most of the current flows on the normally open contact 31a side, and no current flows on the PTC 3 side having resistance. Thus, a current sufficient for driving the inverter 4 flows.

Next, the operation when the high pressure of the refrigeration cycle abnormally rises will be described with reference to the time chart of FIG.
When the high pressure of the refrigeration cycle rises abnormally, the high pressure switch 20 operates and opens. When the high-voltage switch 20 is operated and opened, the energization to the coil 31c of the relay 31 is cut off. However, a current flows between the coil 31c of the relay 31 and the return diode D, and the normally open contact 31a is opened from the energization cut-off. There is a time delay of about 10msec before opening. That is, even when the high-voltage switch 20 is operated and opened, the normally open contact 31a is not immediately opened, and energization from the commercial AC power source 1 to the inverter 4 through the normally open contact 31a continues.

  On the other hand, in the operation detection circuit 39 that detects the operation of the high-voltage switch 20, simultaneously with the operation of the high-voltage switch 20, the input signal from the operation detection circuit 39 to the MCU 40 switches from logic “1” to logic “0”. The MCU 40 monitors the input signal from the operation detection circuit 39 (including noise removal processing), confirms that the input signal has definitely changed to logic “0”, and stops driving the inverter 4. This drive stop timing can be executed in 10 msec or less, and can be executed before the timing at which the normally open contact 31a of the relay 31 opens.

  When the drive of the inverter 4 is stopped, the current flowing to the inverter 4 through the normally open contact 31a is greatly reduced. In this state, the normally open contact 31a is opened (energization cut off), so that the burden on the normally open contact 31a at the time of opening is extremely small. Therefore, the life of the relay 31 is improved.

  Even if the operation detection circuit 39 or the MCU 40 fails and the drive of the inverter 4 cannot be stopped, the high voltage switch 20 and the coil 31c of the relay 31 are connected in series. Is securely shut off and safe. In this case, when the normally open contact 31a is opened, a current flows through the PTC 3 to the inverter 4 side. However, because of the resistance of the PTC 3, a current sufficient to continuously drive the inverter 4 does not flow, and thus the inverter 4 continues to be driven. It is safe.

[2] A second embodiment will be described.
As shown in FIG. 3, one end of a coil 31c that is DC driven of a relay (first relay) 31 is connected to a positive terminal to which a DC voltage of 12 V is applied via a normally open contact 32a of the relay (second relay) 32. The other end of the coil 31c is grounded via the collector and emitter of the transistor 33. That is, the normally open contact 32 a of the relay 32 and the collector and emitter of the transistor 33 are inserted into the energization path for the coil 31 c of the relay 31.

  The relay 32 includes a normally open contact 32a and a DC-driven coil 32c. A freewheeling diode D is connected between the two ends of the coil 32c so as to be in the opposite direction to the DC voltage.

  Further, one end of the coil 32c of the relay 32 is connected to the positive terminal to which the DC voltage 12V is applied via the high voltage switch 20, and the other end of the coil 32c is grounded. That is, the high voltage switch 20 is inserted into the energization path for the coil 32 c of the relay 32. In this case, a terminal plate 9 is provided for connecting the high voltage switch 20.

  An operation detection circuit 39 is connected to the energization path between the high voltage switch 20 and the coil 32c.

The main control means and the relay control means of the MCU 40 have the control means (11) and (12) based on mutual linkage.
(11) Control means for turning on the transistor 33 and starting driving the inverter 4 with a predetermined time (several seconds) delay after the commercial AC power supply 1 is turned on (= application of a DC voltage of 5 V).
(12) Control means for stopping the drive of the inverter 4 when the operation of the detection means in the MCU 40 is detected.
Other configurations are the same as those of the first embodiment. Therefore, the description is omitted.

The operation when the high pressure of the refrigeration cycle abnormally rises will be described with reference to the time chart of FIG.
When the high pressure of the refrigeration cycle rises abnormally, the high pressure switch 20 operates and opens. When the high voltage switch 20 is operated and opened, the energization to the coil 32c of the relay 32 is cut off. However, the coil 32c of the relay 32 and the return diode D are turned off by 10msec until the normally open contact 32a is opened after the energization is cut off. About a time delay occurs. That is, even if the high-voltage switch 20 is operated and opened, the normally open contact 32a is not immediately opened. Therefore, the energization of the coil 31c of the relay 31 continues and the normally open contact 31a is not opened. To the inverter 4 through the normally open contact 31a continues.

  Thereafter, when the normally open contact 32a is opened, the energization to the coil 31c of the relay 31 is cut off, but by the coil 31c of the relay 31 and the return diode D, 10 msec from when the energization is cut off until the normally open contact 31a is opened. About a time delay occurs. That is, even if the normally open contact 32a of the relay 32 is opened, the normally open contact 31a of the relay 31 is not immediately opened, and energization through the normally open contact 31a from the commercial AC power supply 1 to the inverter 4 continues. It will be.

  However, the operation of the high voltage switch 20 is detected by the operation detection circuit 39, and simultaneously with the operation of the high voltage switch 20, the input signal from the operation detection circuit 39 to the MCU 40 is switched from logic "1" to logic "0". The MCU 40 monitors the input signal from the operation detection circuit 39 (including noise removal processing), and stops driving the inverter 4 when it is confirmed that the input signal is surely logic “0”. This drive stop timing is earlier than the timing at which the normally open contact 31a of the relay 31 opens.

  When the drive of the inverter 4 is stopped, the current flowing to the inverter 4 through the normally open contact 31a is greatly reduced. In this state, the normally open contact 31a is opened (energization cut off), so that the burden on the normally open contact 31a at the time of opening is extremely small. Therefore, the life of the relay 31 is greatly improved.

  Moreover, since there is a two-stage time delay (up to 20 msec) due to the two relays 31 and 32 from when the high-voltage switch 20 operates until the normally open contact 31a of the relay 31 opens, for some reason, the MCU 40 Even if the drive stop of the inverter 4 is slightly delayed, there is a high possibility that the normally open contact 31a will be opened later than the drive stop timing, and the reliability with respect to the improvement of the life of the relay 31 is improved.

[3] A third embodiment will be described.
As shown in FIG. 5, an inrush current limiting resistor 50 is provided in a current path between the commercial AC power supply 1 and the inverter 4 via a normally open contact 51 a of a relay (first relay) 51 instead of the PTC 3. Is inserted. The relay 51 includes a normally open contact 51a and a DC-driven coil 51c. A freewheeling diode D is connected between the both ends of the coil 51c so as to be in the opposite direction to the DC voltage.

  The normally open contact 31a of the relay (second relay) 31 is connected in parallel with the series circuit of the resistor 50 and the normally open contact 51a.

  Furthermore, one end of each of the coils 31 c and 51 c of the relays 31 and 51 is connected to the positive terminal to which the DC voltage 12 V is applied via the normally open contact 32 a of the relay (third relay) 32. The other end of the coil 31 c is grounded via the collector and emitter of the transistor (second switch means) 33. The other end of the coil 51 c is grounded through the collector and emitter of an NPN transistor (first switch means) 52.

  A DC voltage of 5 V is applied between the base and emitter of the transistor 33 via a resistor 34, and the collector and emitter of an NPN transistor 35 are connected between the base and emitter of the transistor 33. The base of the transistor 35 is connected to the output terminal A of the MCU 40 via the resistor 36.

  A DC voltage of 5 V is applied between the base and emitter of the transistor 52 via a resistor 53, and the collector and emitter of an NPN transistor 54 are connected between the base and emitter of the transistor 52. The base of the transistor 54 is connected to the output terminal B of the MCU 40 via the resistor 55.

  A display unit 43 is connected to the MCU 40.

The main control unit and the relay control unit of the MCU 40 have the control units (21) and (22) based on mutual linkage.
(21) Control means for turning on the transistor 52 when the commercial AC power supply 1 is turned on (= application of a DC voltage of 5 V), and then turning on the transistor 33 with a predetermined time delay and starting driving the inverter 4.

  (22) Control means for stopping the drive of the inverter 4 when the operation of the detection means in the MCU 40 is detected.

  Other configurations are the same as those of the second embodiment. Therefore, the description is omitted.

Next, the operation will be described with reference to the time chart of FIG.
The MCU 40 turns off the transistor 54 when the commercial AC power supply 1 is turned on (operation start). If the transistor 54 is off, the transistor 52 is turned on, and an energization path for the coil 51c of the relay 51 is formed. Thereby, the normally open contact 51a of the relay 51 is closed.

  At the same time, the MCU 40 turns on the transistor 35. When the transistor 35 is turned on, the transistor 33 is turned off, and the energization path for the coil 31c of the relay 31 is interrupted. Thereby, the normally open contact 31a of the relay 31 maintains an open state.

  Thus, the normally open contact 51a is closed and the normally open contact 31a is kept open, so that a current flows from the commercial AC power source 1 to the inverter 4 through the resistor 50 and the normally open contact 51a. In this case, the inrush current does not flow through the inverter 4 due to the resistance of the resistor 50.

  A few seconds after the commercial AC power supply 1 is turned on, the MCU 40 turns off the transistor 35 and drives the inverter 4. When the transistor 35 is turned off, the transistor 33 is turned on, and an energization path for the coil 31c of the relay 31 is formed. Thereby, the normally open contact 31a of the relay 31 is closed.

  When the normally open contact 31a is closed, most of the current flows on the normally open contact 31a side, and no current flows on the resistor 50 side. Thus, a current sufficient for driving the inverter 4 flows.

  Shortly after closing the normally open contact 31a, the MCU 40 turns on the transistor 54. When the transistor 54 is turned on, the transistor 52 is turned off, and the energization path for the coil 51c of the relay 51 is interrupted. Thereby, the normally open contact 51a of the relay 51 is opened. By this opening, the energization path through the resistor 50 is interrupted.

Next, a case where the high pressure of the refrigeration cycle has abnormally increased will be described.
When the high pressure of the refrigeration cycle rises abnormally, the high pressure switch 20 operates and opens. When the high voltage switch 20 is operated and opened, the energization to the coil 32c of the relay 32 is cut off. However, the coil 32c of the relay 32 and the return diode D are turned off by 10msec until the normally open contact 32a is opened after the energization is cut off. About a time delay occurs. That is, even if the high-voltage switch 20 is operated and opened, the normally open contact 32a is not immediately opened. Therefore, the energization of the coil 31c of the relay 31 continues and the normally open contact 31a is not opened. To the inverter 4 through the normally open contact 31a continues.

  Thereafter, when the normally open contact 32a is opened, the energization to the coil 31c of the relay 31 is cut off, but by the coil 31c of the relay 31 and the return diode D, 10 msec from when the energization is cut off until the normally open contact 31a is opened. About a time delay occurs. That is, even if the normally open contact 32a of the relay 32 is opened, the normally open contact 31a of the relay 31 is not immediately opened, and energization through the normally open contact 31a from the commercial AC power supply 1 to the inverter 4 continues. It will be.

  However, the operation of the high voltage switch 20 is detected by the operation detection circuit 39, and simultaneously with the operation of the high voltage switch 20, the input signal from the operation detection circuit 39 to the MCU 40 is switched from logic "1" to logic "0". The MCU 40 monitors the input signal from the operation detection circuit 39 and stops driving the inverter 4 when it is confirmed that the input signal is logic “0”. This drive stop timing is earlier than the timing at which the normally open contact 31a of the relay 31 opens.

  When the drive of the inverter 4 is stopped, the current flowing to the inverter 4 through the normally open contact 31a is greatly reduced. In this state, the normally open contact 31a is opened (energization cut off), so that the burden on the normally open contact 31a at the time of opening is extremely small. Therefore, the life of the relay 31 is greatly improved.

  In addition, when the MCU 40 confirms that the input signal from the operation detection circuit 39 is logic “0”, the MCU 40 writes data indicating that an abnormal increase in the high pressure has occurred in the memory 42, and the abnormal increase in the high pressure has occurred. A message to the effect is displayed on the display unit 43.

  Also in the third embodiment, there is a two-stage time delay due to the mechanical characteristics of the two relays 31 and 32 from when the high-voltage switch 20 operates until the normally-open contact 31a of the relay 31 opens. Therefore, even if the drive stop of the inverter 4 by the MCU 40 is delayed for some reason, there is a high possibility that the normally open contact 31a opens after the drive stop timing, and the reliability for improving the life of the relay 31 is improved. To do.

  In addition, this invention is not limited to said each embodiment, A various deformation | transformation implementation is possible in the range which does not change a summary.

It is a figure which shows the structure of 1st Embodiment. The time chart for demonstrating the effect | action of 1st Embodiment. It is a figure which shows the structure of 2nd Embodiment. The time chart for demonstrating the effect | action of 2nd Embodiment. It is a figure which shows the structure of 3rd Embodiment. The time chart for demonstrating the effect | action of 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Commercial AC power source, 3 ... PTC, 4 ... Inverter, 10 ... Compressor motor, 11 ... Compressor, 13 ... Outdoor heat exchanger, 15 ... Indoor heat exchanger, 20 ... High pressure switch, 31, 32, 51 ... Relay, 31a, 32a, 51a ... Normally open contact, 33 ... NPN transistor (switch means), 40 ... MCU, 52 ... NPN transistor (switch means)

Claims (3)

A refrigeration cycle in which a refrigerant is circulated by connecting a compressor, an outdoor heat exchanger, a decompressor, and an indoor heat exchanger;
An inverter connected to a commercial AC power source and outputting driving power to the motor of the compressor;
A resistance element for inrush current limiting inserted into an energization path between the commercial AC power source and the inverter;
A relay having a normally open contact and a DC drive coil connected in parallel with the resistive element;
Switch means inserted into the energization path for the coil of the relay;
A high-pressure switch that is inserted into the energization path for the coil of the relay and that operates and opens when the high-pressure pressure of the refrigeration cycle rises abnormally;
Detecting means for detecting the operation of the high-pressure switch;
Control means for turning on the switch means and starting driving the inverter with a predetermined time delay from turning on the commercial AC power supply, and stopping the driving of the inverter when the operation of the detecting means is detected;
An air conditioner comprising: A refrigeration cycle in which a refrigerant is circulated by connecting a compressor, an outdoor heat exchanger, a decompressor, and an indoor heat exchanger;
An inverter connected to a commercial AC power source and outputting driving power to the motor of the compressor;
A resistance element for inrush current limiting inserted into an energization path between the commercial AC power source and the inverter;
A first relay having a normally open contact and a DC drive coil connected in parallel with the resistive element;
Switch means inserted into an energization path for the coil of the first relay;
A second relay having a normally open contact and a DC drive coil inserted into a current path to the coil of the first relay;
A high-pressure switch that is inserted into an energization path to the coil of the second relay and that is activated and opened when the high-pressure pressure of the refrigeration cycle rises abnormally;
Detecting means for detecting the operation of the high-pressure switch;
Control means for turning on the switch means and starting driving the inverter with a predetermined time delay from turning on the commercial AC power supply, and stopping the driving of the inverter when the operation of the detecting means is detected;
An air conditioner comprising: A refrigeration cycle in which a refrigerant is circulated by connecting a compressor, an outdoor heat exchanger, a decompressor, and an indoor heat exchanger;
An inverter connected to a commercial AC power source and outputting driving power to the motor of the compressor;
A first relay having a normally open contact and a DC drive coil;
An inrush current limiting resistor inserted into a current path between the commercial AC power source and the inverter via a normally open contact of the first relay;
A second relay having a normally open contact and a DC drive coil connected in parallel with a series circuit of the resistor and the normally open contact;
First switch means inserted into the energization path for the coil of the first relay;
A second switch means inserted into an energizing path for the coil of the second relay;
A third relay having a normally open contact and a DC drive coil inserted into a current path for the coil of the first relay and the coil of the second relay;
A high-pressure switch that is inserted into an energization path for the coil of the third relay and that is activated and opened when the high-pressure pressure of the refrigeration cycle is abnormally increased;
Detecting means for detecting the operation of the high-pressure switch;
When the commercial AC power is turned on, the first switch means is turned on, and then the second switch means is turned on with a predetermined time delay, and then the inverter is started to be driven. Control means for stopping the driving of
An air conditioner comprising:

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