JP6396679B2 - Overcurrent detection circuit, air conditioner, thermistor mounting structure, and electrical equipment - Google Patents

Description

  The present invention relates to an overcurrent detection circuit, an air conditioner, a thermistor mounting structure, and an electrical device. Note that the electrical device according to the present invention includes at least one of an overcurrent detection circuit and a thermistor mounting structure.

  FIG. 18 shows a configuration example of a main part of a conventional air conditioner. The conventional air conditioner includes an inverter circuit 101, a microcomputer 102, an inverter control circuit 103, a compressor three-phase AC motor 104, a reactor L1, a diode bridge circuit DB1, an electrolytic capacitor C1, and a shunt resistor. Rd.

  The commercial AC voltage output from the commercial AC power supply 100 is rectified by the diode bridge circuit DB1, smoothed by the electrolytic capacitor C1, and converted into a DC voltage. The DC voltage is supplied to the inverter circuit 101. The power factor is improved by the reactor L1.

  The inverter circuit 101 has a circuit configuration in which three series circuits in which two IGBTs (Insulated Gate Bipolar Transistors) are directly connected are connected in parallel. The voltage at the connection node between the IGBTs in each series connection circuit is the inverter circuit 101. The output voltage of each phase. A diode is connected between the collector and emitter of each IGBT so as to be in the forward direction from the emitter to the collector. The inverter circuit 101 converts the DC voltage into a three-phase sinusoidal voltage and supplies it to the three-phase AC motor 104.

  The microcomputer 102 instructs the inverter control circuit 103 about the drive control content of the inverter circuit 101 based on the indoor environment detected by the sensor and the operating state set by the user's remote control operation.

  The inverter control circuit 103 drives the inverter circuit 101 in accordance with instructions from the microcomputer 102. Further, the inverter control circuit 103 detects an overcurrent that can flow through the inverter circuit 101 using the potential difference between both ends of the shunt resistor Rd. When the inverter control circuit 103 detects that an overcurrent is flowing through the inverter circuit 101 and the compressor, the inverter control circuit 103 holds all the IGBTs of the inverter circuit 101 in an OFF state and stops the operations of the inverter circuit 101 and the compressor.

  Further, in the installation of the air conditioner, a forced operation is performed in order to check whether the compressor and the fan normally operate. The forced operation is also performed for recovering the refrigerant in the heat exchanger and the piping when moving due to moving or the like, and is also performed when the air conditioner is not functioning normally.

  In a separate type air conditioner including an indoor unit and an outdoor unit, a switch for instructing the start of forced operation is usually provided in the indoor unit. In the air conditioner proposed in Patent Document 2, a switch for instructing the start of forced operation is provided in the outdoor unit to improve workability.

  Also, conventionally, when the compressor mounted on the air conditioner is large, it is equipped with a mounting angle that fixes the thermistor inside the terminal cover member that covers the terminal protruding from the upper surface of the compressor Using the angle, a thermistor was attached with a dedicated spring, and the temperature of the upper surface of the compressor was detected by the thermistor. On the other hand, if the compressor mounted on the air conditioner is not large, the terminal cover member is not equipped with a mounting angle, so a thermistor is attached to the compressor discharge pipe with a spring, and the compressor discharge pipe The temperature was detected with a thermistor.

Japanese Patent No. 4589453 Japanese Patent Laid-Open No. 2-150648 JP 61-39504 A JP-A-9-210311

  In the conventional air conditioner shown in FIG. 18, when a current flows through the stator coil of the three-phase AC motor 104, a magnetic field is generated in the stator of the three-phase AC motor 104. This magnetic field acts on the magnet installed in the rotor, and the rotor rotates.

  When a large current flows through the stator coil of the three-phase AC motor 104, the magnetic field generated in the stator of the three-phase AC motor 104 also increases. If this magnetic field becomes excessive, the magnetic poles of the magnets installed on the rotor of the three-phase AC motor 104 will weaken, and the rotor will not rotate smoothly.

  The types of magnets installed on the rotor of the three-phase AC motor 104 include magnetized ferrite and rare earth. And even if the electric current which flows into a stator coil is the same, the weakening level of a magnetic pole changes with kinds of magnet installed in the rotor. Therefore, in order to suppress the weakening of the magnetic pole below a predetermined level, the overcurrent detection level must be adjusted according to the type of magnet installed in the rotor.

  Further, if the type of the power semiconductor element used in the inverter circuit (in the example shown in FIG. 18, the IGBT of the inverter circuit 101) is different, the maximum rated current value of the power semiconductor element is different.

  Although there are cases where compressors and inverter circuits are common in different types of air conditioners, there are multiple types of compressors depending on the type of air conditioner, and power semiconductor elements used in inverter circuits There are several types of. For this reason, there are a plurality of overcurrent detection levels.

  In the conventional air conditioner shown in FIG. 18, in order to change the overcurrent detection level of the overcurrent detection circuit, it is necessary to change the resistance value of the shunt resistor Rd, that is, to change the type of the shunt resistor Rd to be used. Yes, it took time and effort to set the overcurrent detection level of the overcurrent detection circuit. Further, since it is necessary to change the type of the shunt resistor Rd to be used, the overcurrent detection circuit cannot be standardized.

  Note that the air conditioner proposed in Patent Document 1 uses the overcurrent detection circuit to perform overheat protection, but it is not easy to change the overcurrent detection level (current limit value) of the overcurrent detection circuit. This is the same as the conventional air conditioner shown in FIG. 18 in that it is necessary to change the type of the temperature resistance element.

  Regarding the forced operation, as described above, in the air conditioner proposed in Patent Document 2, a switch for instructing the start of forced operation is provided in the outdoor unit. However, in the configuration of the air conditioner proposed in Patent Document 2, it is necessary to add a switch for instructing the start of forced operation to the outdoor unit, which increases the cost.

  Also, regarding the structure of the thermistor, in the structure where the thermistor is attached to the discharge pipe of the compressor with a spring and the temperature of the discharge pipe of the compressor is detected by the thermistor, when the refrigerant is circulating, the top surface of the compressor Although there was a slight difference between the temperature of the compressor and the temperature of the discharge pipe of the compressor, it was a level at which there was no problem in controlling the air conditioner. However, when the stator winding of the motor mounted inside the compressor is energized without circulating refrigerant, the temperature of the upper surface of the compressor rises, but the temperature of the discharge pipe of the compressor almost rises. Therefore, there is a large difference between the temperature of the upper surface of the compressor and the temperature of the discharge pipe of the compressor, and the temperature of the winding provided in the compressor cannot be accurately detected. For this reason, there existed a possibility that the coil | winding provided in the compressor might become abnormally high temperature.

  Note that the thermistor mounting structure proposed in Patent Document 3 and Patent Document 4 is applied to a compressor to which a terminal cover member that is not equipped with a mounting angle for fixing the thermistor is applied. The temperature cannot be detected.

  The problem related to the overcurrent detection circuit is not limited to an air conditioner, and may be a problem that can occur in all electrical devices including an overcurrent detection circuit. Moreover, the problem regarding attachment of the thermistor is not limited to an air conditioner, and may be a problem that can occur in general electrical equipment including a thermistor and a compressor.

  In view of the above situation, it is a first object of the present invention to provide an overcurrent detection circuit capable of easily setting an overcurrent detection level and an electric device including the same.

  In view of the above situation, a second object of the present invention is to provide an air conditioner that can perform forced operation at low cost.

  In view of the above situation, it is a third object of the present invention to provide a thermistor mounting structure with high accuracy in detecting the temperature of a winding provided inside a compressor, and an electric device including the same.

  In order to achieve the first object, an overcurrent detection circuit according to the present invention adjusts a value of a current drive transistor provided on a conductor line and a control current supplied to a control terminal of the current drive transistor. And an adjustment unit, wherein an overcurrent flowing through the conductor line is detected based on a voltage between the first terminal and the second terminal of the current-driven transistor (first configuration).

  In the overcurrent detection circuit of the first configuration, the adjustment unit includes a pulse circuit that outputs a pulse voltage signal and a smoothing circuit that smoothes the pulse voltage signal, and adjusts an on-duty of the pulse voltage signal. It is desirable to adopt a configuration (second configuration) for adjusting the value of the control current.

  In the overcurrent detection circuit of the second configuration, it is desirable that the adjustment unit includes a resistor (third configuration) provided between the smoothing circuit and a control terminal of the current-driven transistor. .

  In order to achieve the second object, an air conditioner according to the present invention includes a printed circuit board, a printed circuit board support that supports the printed circuit board, and a plurality of devices for fixing the printed circuit board to the printed circuit board support. And whether or not a predetermined one of the plurality of screws is removed, and the forced operation is turned on / off according to whether or not a predetermined one of the plurality of screws is removed. A configuration including a control unit to be switched (fourth configuration).

  In the air conditioner of the fourth configuration, the printed circuit board has a first conductive pattern and a second conductive pattern, and a predetermined voltage is applied to the first conductive pattern, and the second When the detection terminal of the control unit is connected to the conductive pattern and a predetermined one of the plurality of screws is not removed, the plurality of the first conductive pattern and the second conductive pattern are the plurality. And when the predetermined one of the plurality of screws is removed, the first conductive pattern and the second conductive pattern are electrically connected to each other. It is desirable to adopt a configuration that is not connected to (a fifth configuration).

  In the air conditioner having the fifth configuration, the printed circuit board includes a first conductor provided on an end portion of the first conductive pattern, and a first conductor provided on an end portion of the second conductive pattern. 2 and a predetermined one of the plurality of screws is not removed, the predetermined one head of the plurality of screws is the first conductor and the second It is desirable to adopt a configuration (sixth configuration) in contact with the conductor.

  In order to achieve the third object, a thermistor mounting structure according to the present invention comprises a thermistor, a compressor, a terminal cover member that covers a terminal protruding from the upper surface of the compressor, and the terminal cover member. A bolt for fixing to the compressor, and the thermistor has a temperature sensing part, a fixing part in which a through hole is formed, and a connecting part for connecting the temperature sensing part and the fixing part. In the state where the bolt penetrates the through hole, the thermistor is fixed to the compressor by the bolt, and the thermistor is fixed to the compressor, the temperature sensing portion is on the upper surface of the compressor. The configuration is in contact (seventh configuration).

  In the attachment structure of the thermistor of the seventh configuration, the temperature sensing unit includes an exterior part connected to the fixed part by the connection part, and an interior part detachable from the exterior part (first 8 configuration).

  In order to achieve at least one of the first and third objects, an electrical device according to the present invention includes an overcurrent detection circuit having any one of the first to third configurations, and any one of the seventh to eighth configurations. It is set as the structure (9th structure) provided with at least one thermistor attachment structure of the structure.

  According to the overcurrent detection circuit and the electrical apparatus including the same according to the present invention, the adjustment unit adjusts the value of the control current in software, so that the overcurrent detection level can be set while using the same component (same hardware). Can be changed. Thereby, the overcurrent detection level can be easily set and the overcurrent detection circuit can be standardized.

  According to the air conditioner according to the present invention, the forced operation is switched on / off depending on whether or not a predetermined one of the plurality of screws for fixing the printed circuit board to the printed circuit board support is removed. A predetermined one of the plurality of screws also serves as a switch for switching on / off of the forced operation. Thus, forced operation can be performed at low cost.

  According to the thermistor mounting structure and the electric apparatus including the thermistor according to the present invention, the thermistor is configured using a bolt for fixing the terminal cover member to the compressor in a state where the temperature sensing portion of the thermistor is in contact with the upper surface of the compressor. Can be fixed to the compressor. As a result, a compression with a large temperature difference from the temperature of the winding provided in the compressor when the stator winding of the motor mounted in the compressor is energized without circulating refrigerant. Since the temperature of the upper surface of the compressor with a small temperature difference is detected instead of the temperature of the discharge pipe of the machine, the temperature of the winding provided in the compressor can be detected with high accuracy.

1 is an external perspective view of an air conditioner according to each embodiment of the present invention. It is a figure which shows the refrigerating cycle of the air conditioner which concerns on each embodiment of this invention. It is a principal part block diagram of the air conditioner which concerns on 1st Embodiment of this invention. It is a wave form diagram of a pulse voltage signal and an analog current signal. It is a wave form diagram of a pulse voltage signal and an analog current signal. It is a principal part block diagram of the air conditioner which concerns on 2nd Embodiment of this invention. It is a principal part block diagram of the air conditioner which concerns on 3rd Embodiment of this invention. It is a partial top view of the printed circuit board in 3rd Embodiment of this invention. It is a partial top view of the printed circuit board in 3rd Embodiment of this invention. It is a fragmentary sectional view of the printed circuit board in 3rd Embodiment of this invention cut | disconnected by the dashed-dotted line of FIG. It is the equivalent circuit schematic in 3rd Embodiment of this invention. It is a front view of a compressor with which an air harmony machine concerning a 4th embodiment of the present invention is provided. It is a top view of a compressor with which an air harmony machine concerning a 4th embodiment of the present invention is provided. It is a top view of the terminal cover member with which a compressor is mounted | worn. It is a top view of the conventional thermistor. It is a top view of the thermistor used in 4th Embodiment of this invention. It is a front view of the thermistor used in 4th Embodiment of this invention. It is a front view of the other thermistor used in 4th Embodiment of this invention. It is a principal part block diagram of the air conditioner of a prior art example.

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

  FIG. 1 is an external perspective view of an air conditioner according to each embodiment of the present invention. The air conditioner according to each embodiment of the present invention is a separation type air conditioner including an indoor unit 1 and an outdoor unit 2. The air conditioner according to each embodiment of the present invention includes a VA line 3 for transmitting electric power and a control signal between the indoor unit 1 and the outdoor unit 2, and a refrigerant between the indoor unit 1 and the outdoor unit 2. Refrigerant pipes 4 and 5, a drain pipe 6 for discharging water, and a power plug 7 provided at the end of a power cord extending from the indoor unit 1. Although not shown in FIG. 1, the VA line 3, the refrigerant pipes 4 and 5, and the drain pipe 6 are usually covered together with a decorative cover.

  FIG. 2 is a diagram showing a refrigeration cycle of the air conditioner according to each embodiment of the present invention. In FIG. 2, the same parts as those in FIG.

  In the outdoor unit 2, a compressor 11, a four-way valve 12, an outdoor heat exchanger 13, an expansion valve 14, and an outdoor fan 15 are provided. An indoor heat exchanger 16 and an indoor fan 17 are provided in the indoor unit 1.

  The compressor 11 operates the refrigeration cycle by circulating the refrigerant in the refrigerant pipe 18. A part of the refrigerant pipe 18 corresponds to the refrigerant pipes 4 and 5 for circulating the refrigerant between the indoor unit 1 and the outdoor unit 2.

  The outdoor heat exchanger 13 and the indoor heat exchanger 16 have a large number of fins (not shown) close to the refrigerant pipe 18 and exchange heat with air passing between the fins.

  Each end of the outdoor heat exchanger 13 and the indoor heat exchanger 16 is connected to the compressor 11 via a four-way valve 12 and a refrigerant pipe 18. The other ends of the outdoor heat exchanger 13 and the indoor heat exchanger 16 are connected to each other via an expansion valve 14 and a refrigerant pipe 18.

  The outdoor fan 15 is disposed opposite to the outdoor heat exchanger 13. Outdoor air is supplied to the outdoor heat exchanger 13 by driving the outdoor fan 15, and heat exchange between the outdoor heat exchanger 13 and the outdoor air is promoted. The air that has exchanged heat with the outdoor heat exchanger 13 is exhausted to the outside through an exhaust port (see FIG. 1) that faces the outdoor fan 15 and opens in front of the outdoor unit 2.

  The indoor heat exchanger 16 and the indoor fan 17 are arranged in a ventilation passage (not shown) provided in the indoor unit 1. Indoor air flows into the ventilation passage by driving the indoor fan 17 and is supplied to the indoor heat exchanger 16, and heat exchange between the air flowing through the ventilation passage and the indoor heat exchanger 16 is performed. The air that has exchanged heat with the indoor heat exchanger 16 is sent into the room through a blowout opening (see FIG. 1) that opens in the operating state below the indoor unit 1 and closes in the operation stop state.

  During the heating operation, the outdoor fan 15 and the indoor fan 17 are driven, and the four-way valve 12 is switched as indicated by a solid line in the figure. Thus, the refrigerant flows in the direction indicated by the arrow A by driving the compressor 11, and the high-temperature and high-pressure refrigerant compressed by the compressor 11 is condensed while releasing heat in the indoor heat exchanger 16.

  The high-temperature refrigerant becomes low-temperature and low-pressure at the expansion valve 14 and is sent to the outdoor heat exchanger 13. The refrigerant flowing into the outdoor heat exchanger 13 evaporates while absorbing heat to become a low-temperature gas refrigerant, and is sent to the compressor 11. By this refrigeration cycle, the air that has exchanged heat with the indoor heat exchanger 16 that is the high temperature part of the refrigeration cycle is sent out indoors by the indoor fan 17 and the room is heated. In addition, the air exchanged with the outdoor heat exchanger 13 that is a low temperature part of the refrigeration cycle is exhausted to the outside by the outdoor fan 15.

  During the cooling operation, the outdoor fan 15 and the indoor fan 17 are driven, and the four-way valve 12 is switched as indicated by a broken line in the figure. As a result, the refrigerant flows in the direction opposite to the arrow A by driving the compressor 11, the indoor heat exchanger 16 becomes the low temperature part of the refrigeration cycle, and the outdoor heat exchanger 13 becomes the high temperature part of the refrigeration cycle. The air that has exchanged heat with the indoor heat exchanger 16 is sent out indoors by the indoor fan 17 to cool the room. Water generated by agglomeration of water vapor in the air exchanged with the indoor heat exchanger 16 is discharged to the outside from the drain pipe 6 (see FIG. 1). In addition, the air exchanged with the outdoor heat exchanger 13 that is a high temperature part of the refrigeration cycle is exhausted to the outside by the outdoor fan 15.

<First Embodiment>
FIG. 3 is a main part configuration diagram of the air conditioner according to the first embodiment of the present invention. In FIG. 3, the same parts as those in FIG. In the present embodiment, a current driven NPN bipolar transistor Q1 (hereinafter abbreviated as “transistor Q1”) corresponds to the “current driven transistor” recited in the claims, and includes a microcomputer 102, a resistor R1, The smoothing circuit including the capacitor C2 and the resistor R2 correspond to the “regulator” described in the claims, and the collector, emitter, and base of the transistor Q1 are “first terminal” described in the claims, The microcomputer 102 corresponds to the “second terminal” and the “control terminal”, and the microcomputer 102 corresponds to the “pulse circuit” recited in the claims.

  The air conditioner according to this embodiment is different from the conventional air conditioner shown in FIG. 18 in that a transistor Q1 is provided instead of the shunt resistor Rd, a smoothing circuit including the resistor R1 and the capacitor C2, and a voltage signal as a current signal. A resistor R2 for conversion into the transistor Q1 and a diode D1 connected in a forward direction from the emitter to the collector between the collector and the emitter of the transistor Q1 are added. Note that the switching element of the inverter circuit 101 may be a power switching element other than the IGBT.

  In the present embodiment, the microcomputer 102 has a function of generating the pulse voltage signal S1 and a function of adjusting the on-duty of the pulse voltage signal S1 by software. The microcomputer 102 outputs the pulse voltage signal S1 to a smoothing circuit composed of a resistor R1 and a capacitor C2.

  The smoothing circuit including the resistor R1 and the capacitor C2 converts the pulse voltage signal S1 into an analog voltage signal S2 having a value corresponding to the on-duty of the pulse voltage signal S1.

  The resistor R2 converts the analog voltage signal S2 into an analog current signal S3 and supplies the analog current signal S3 to the base of the transistor Q1. Note that if the resistor R2 can be substituted by a line resistance between the smoothing circuit including the resistor R1 and the capacitor C2 and the base of the transistor Q1, the resistor R2 may not be provided.

  The collector-emitter voltage of the transistor Q1 changes according to the analog current signal S3 supplied to the base of the transistor Q1 and the current supplied to the collector of the transistor Q1 through the inverter circuit 101 and the compressor.

  The inverter control circuit 103 detects that an overcurrent flows through the inverter circuit 101 and the compressor when the collector-emitter voltage of the transistor Q1 is equal to or higher than a predetermined value, and turns off all IGBTs in the inverter circuit 101. And the operation of the inverter circuit 101 and the compressor is stopped.

  The microcomputer 102 prevents the current exceeding the maximum overcurrent determined in consideration of the demagnetizing current of the compressor being used and the rated current of the power semiconductor element of the inverter circuit from flowing into the compressor or the inverter circuit. The on-duty of the pulse voltage signal S1 is adjusted.

  When the overcurrent detection level is set low, as shown in FIG. 4A, the on-duty of the pulse voltage signal S1 is decreased and the current value of the analog current signal S3 is decreased. As a result, the base current of the transistor Q1 decreases, and as a result, the collector-emitter voltage of the transistor Q1 increases with the current flowing through the inverter circuit 101 and the compressor supplied to the collector of the transistor Q1 being small. The current detection level is lowered.

  On the other hand, when the overcurrent detection level is set high, as shown in FIG. 4B, the on-duty of the pulse voltage signal S1 is increased and the current value of the analog current signal S3 is increased. As a result, the base current of the transistor Q1 increases, and as a result, the collector-emitter voltage of the transistor Q1 does not increase until the current flowing through the inverter circuit 101 and the compressor and supplied to the collector of the transistor Q1 increases to some extent. The overcurrent detection level becomes higher.

  The advantage of setting the overcurrent detection level high is that the operation does not stop easily due to overcurrent when the compressor rotates at a high speed or when the current flowing through the inverter circuit 101 and the compressor fluctuates due to power fluctuations. is there. In short, as much as possible is possible under the condition that current exceeding the maximum overcurrent determined in consideration of the demagnetizing current of the compressor used and the rated current of the power semiconductor element of the inverter circuit does not flow to the compressor or inverter circuit. It is desirable to increase the current detection level.

  According to the air conditioner according to the present embodiment, the microcomputer 102 adjusts the value of the base current of the transistor Q2 by software, thereby changing the overcurrent detection level while using the same component (same hardware). Can do. Thereby, the overcurrent detection level can be easily set and the overcurrent detection circuit can be standardized.

Second Embodiment
FIG. 5 is a main part configuration diagram of an air conditioner according to a second embodiment of the present invention. In FIG. 5, the same parts as those in FIG. 3 are denoted by the same reference numerals.

  The air conditioner according to this embodiment is different from the air conditioner according to the first embodiment of the present invention in that it does not include a smoothing circuit composed of a resistor R1 and a capacitor C2, and the microcomputer 102 resists a DC voltage signal. It is a point supplied to R2.

  The microcomputer 102 prevents the current exceeding the maximum overcurrent determined in consideration of the demagnetizing current of the compressor being used and the rated current of the power semiconductor element of the inverter circuit from flowing into the compressor or the inverter circuit. The voltage value of the DC voltage signal is adjusted.

  The resistor R2 converts the DC voltage signal into an analog current signal S3 and supplies the analog current signal S3 to the base of the transistor Q1. If the resistor R2 can be substituted with a line resistance between the microcomputer 102 and the base of the transistor Q1, the resistor R2 need not be provided.

  Therefore, in the air conditioner according to the present embodiment as well, the microcomputer 102 adjusts the base current value of the transistor Q2 by software in the same manner as in the air conditioner according to the first embodiment of the present invention. The overcurrent detection level can be changed while using the same hardware. Thereby, the overcurrent detection level can be easily set and the overcurrent detection circuit can be standardized. However, unlike the air conditioner according to the first embodiment of the present invention, the microcomputer 102 needs to have a hardware configuration capable of outputting a multi-value DC voltage signal, and the hardware configuration is slightly complicated. Become.

<Third Embodiment>
FIG. 6: is a principal part permeation | transmission front view of the outdoor unit of the air conditioner concerning 3rd Embodiment of this invention. In FIG. 6, the same parts as those in FIG. 2 are denoted by the same reference numerals. In the present embodiment, the electrical box 109 corresponds to the “printed circuit board support” described in the claims, and the microcomputer 117 corresponds to the “control unit” described in the claims. The first copper foil pattern 110 corresponds to the “first conductive pattern” recited in the claims, and the second copper foil pattern 111 is the “second conductive pattern” recited in the claims. The first solder layer 112 corresponds to the “first conductor” recited in the claims, and the second solder layer 113 refers to the “second conductor” recited in the claims. Corresponds to the “conductor”.

  The outdoor unit 2 includes a compressor 11, an outdoor heat exchanger 13, an outdoor fan 15, an air guide 105 that guides wind generated by the rotation of the outdoor fan 15 to an exhaust port (see FIG. 1), and an installation space for the outdoor fan 15. And a shielding plate 106 that shields the installation space of the compressor 11 and an electrical box 109 for storing a part of a printed circuit board 108 on which electrical components 107 that are components such as an inverter circuit and a power factor correction circuit are mounted. It has been.

  A plurality of through holes are provided on the periphery of the printed circuit board 108, and screw holes corresponding to the through holes of the printed circuit board 108 are provided on the side wall of the electrical box 109. Thereby, the printed circuit board 108 can be fixed to the electrical equipment box 109 using a plurality of screws.

  As shown in the partial top view of the printed circuit board 108 shown in FIG. 7, a through hole 114 corresponding to a predetermined one of the plurality of screws is provided in the printed circuit board 108, and a first hole formed on the printed circuit board 108. One end of the copper foil pattern 110 and the end of the second copper foil pattern 111 formed on the printed circuit board 108 face each other through the through hole 114. Further, a first solder layer 112 is formed on the end portion of the first copper foil pattern 110, and a second solder layer 113 is formed on the end portion of the second copper foil pattern 111.

  As shown in FIG. 7, when a predetermined one of the plurality of screws is removed from the screw holes of the electrical box 109 corresponding to the through holes 114 and the through holes 114, the first copper foil pattern 110 and the first The two conductive patterns 111 are not electrically connected.

  On the other hand, as shown in FIGS. 8 and 9, when a predetermined one of the plurality of screws (screw consisting of the head portion 115 and the shaft portion 116) is not removed, the first copper foil pattern 110 and the second copper foil pattern 110 The copper foil pattern 111 is electrically connected via a screw made up of a head portion 115 and a shaft portion 116. The screw made up of the head portion 115 and the shaft portion 116 preferably has high conductivity, and may be a brass screw, for example. Since the first copper foil pattern 110 and the screw head 115 are electrically connected via the first solder layer 112 having a thickness and a relatively soft thickness, the electrical connection is strengthened. Similarly, the second copper foil pattern 111 and the screw head 115 are electrically connected via the thick and relatively soft second solder layer 113, so that the electrical connection is strengthened.

  The detection terminal 118 of the microcomputer 117 mounted on the printed circuit board 108 is connected to the second copper foil pattern 111 as shown in FIG. A pull-down resistor 119 is also connected to the second copper foil pattern 111. A predetermined voltage (for example, DC 5 V) is applied to the first copper foil pattern 110.

  When the screw composed of the head portion 115 and the shaft portion 116 is not removed, the switch SW1 equivalent to the head portion of the screw is turned on, and a predetermined voltage is applied to the detection terminal 118 of the microcomputer 117. On the other hand, when the screw composed of the head portion 115 and the shaft portion 116 is removed, the switch SW1 equivalent to the screw head portion 115 is turned off, and the detection terminal 118 of the microcomputer 117 becomes the ground potential.

  The microcomputer 117 turns off forced operation when the detection terminal 118 is at a predetermined voltage, and turns on forced operation when the detection terminal 118 is at the ground potential. Although the content of forced operation is not specifically limited, For example, the operation | movement etc. which rotate the motor inside a compressor by predetermined frequency can be mentioned.

  The attachment and detachment of the screw including the head portion 115 and the shaft portion 116 does not require a special tool and can be easily performed using a general-purpose tool (driver).

  When removing the screw composed of the head portion 115 and the shaft portion 116, it is recommended to remove the screw after removing the power supply to prevent an electric shock. After removing the screw, the power can be turned on again to perform forced operation. At this time, one fixing screw is insufficient, but the printed circuit board 108 is somewhat staggered, and the forced operation can be safely performed.

  Even when the screws including the head portion 115 and the shaft portion 116 are attached again, it is recommended to attach the screws after removing the power supply to prevent an electric shock.

  According to the air conditioner according to the present embodiment, on / off of forced operation is switched depending on whether or not a predetermined one of a plurality of screws for fixing the printed circuit board 108 to the electrical box 109 is removed. A predetermined one of the plurality of screws also serves as a switch for switching on / off of the forced operation. Thus, forced operation can be performed at low cost.

  In the present embodiment, the present invention is applied to the outdoor unit 2, but the indoor unit 1 is also provided with a printed circuit board and a printed circuit board support (for example, a housing frame of the indoor unit 1). 1 may apply the present invention. Normally, the indoor unit 1 is provided with a dedicated switch for switching on / off of the forced operation. However, when the present invention is applied to the indoor unit 1, the dedicated switch is abolished to reduce the cost. It is desirable.

<Fourth embodiment>
FIG. 11 is a front view of a compressor included in an air conditioner according to the fourth embodiment of the present invention, and FIG. 12 is a top view of the compressor included in the air conditioner according to the fourth embodiment of the present invention. FIG. 13 is a top view of a terminal cover member attached to the compressor.

  A terminal 121 and a discharge pipe 122 protrude from the upper surface 120 of the compressor. The terminal cover member 124 is attached to the compressor by passing the bolt 123 through the through hole 125 of the terminal cover member 124 and attaching the bolt 123 to the screw hole of the compressor.

  The terminal cover member 124 is not equipped with an attachment angle for fixing the thermistor. Therefore, when a conventional thermistor having a rectangular parallelepiped-shaped temperature sensing part 126 as shown in FIG. 14 and a lead wire extending from the temperature sensing part is used, the temperature sensing part 126 and the upper surface 120 of the compressor are brought into contact with each other. In this state, the thermistor could not be fixed to the compressor.

  Therefore, in this embodiment, a thermistor 127 as shown in FIGS. 15 and 16 is used. The thermistor 127 includes a temperature sensing part 128, a flat plate-like fixing part 130, and a connecting part 131 that connects the temperature sensing part 128 and the fixing part 130. A through hole 129 is formed in the fixing portion 130.

  The terminal cover member 124 and the thermistor 127 can be attached to the compressor by passing the bolt 123 through the through hole 125 of the terminal cover member 124 and the through hole 129 of the thermistor 127 and attaching the bolt 123 to the screw hole of the compressor. it can. There is a step in the thickness direction of the thermistor 127 between the fixed part 130 and the temperature sensitive part 128, and the temperature sensitive part 128 contacts the upper surface 120 of the compressor in a state where the thermistor 127 is fixed to the compressor. Thus, the value of the step (shape of the connecting portion 131) is designed.

  As a result, a compression with a large temperature difference from the temperature of the winding provided in the compressor when the stator winding of the motor mounted in the compressor is energized without circulating refrigerant. Since the temperature of the upper surface 120 of the compressor having a small temperature difference is detected instead of the temperature of the discharge pipe 122 of the machine, the temperature of the winding provided inside the compressor can be detected with high accuracy. Even when the stator winding of the motor mounted inside the compressor is energized without circulating the refrigerant, the temperature of the winding provided inside the compressor and the upper surface 120 of the compressor The difference from the temperature is at most about 5 to 10 ° C.

  Instead of using the thermistor 127 as shown in FIGS. 15 and 16, the thermistor 127 shown in FIG. 17 may be used. In the thermistor 127 shown in FIG. 17, the temperature sensing part 128 has an exterior part 132 connected to the fixed part 130 by a connection part 131, and an interior part 133 that can be attached to and detached from the exterior part 132.

  In the thermistor 127 shown in FIG. 17, since the conventional thermistor shown in FIG. 14 can be used for the interior part 133, cost reduction can be achieved. In order to further reduce the cost, it is desirable that the fixing portion 130, the connecting portion 131, and the exterior portion 132 are integrally formed.

  Further, in the thermistor 127 as shown in FIG. 15 and FIG. 16 and the thermistor 127 as shown in FIG. 17, the connecting portion 131 is elastically deformed in a state where the thermistor 127 is fixed to the compressor. It is desirable that the urging force is generated in the direction in which the portion 128 is pressed against the upper surface 120 of the compressor. This ensures contact between the temperature sensing unit 128 and the upper surface 120 of the compressor.

<Summary>
Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention. For example, in the first embodiment, the second embodiment, and the fourth embodiment described above, the overcurrent detection circuit and the thermistor mounting structure are each mounted on an air conditioner, but are mounted on other electrical devices such as a refrigerator. Also good. Moreover, you may implement combining at least 2 of each embodiment of this invention suitably.

  The overcurrent detection circuit described above includes a current drive transistor (Q1) provided on a conductor line and an adjustment unit that adjusts the value of the control current (S3) supplied to the control terminal of the current drive transistor (Q1). (102, R1, C2, R2) for detecting an overcurrent flowing through the conductor line based on a voltage between the first terminal and the second terminal of the current-driven transistor (Q1) (first configuration) ).

  According to such a configuration, the adjustment unit adjusts the value of the control current of the current-driven transistor in software, so that the overcurrent detection level can be changed while using the same component (same hardware). Thereby, the overcurrent detection level can be easily set and the overcurrent detection circuit can be standardized.

  In the overcurrent detection circuit having the first configuration, the adjustment unit outputs a pulse voltage signal (S1) and a smoothing circuit (R1, R2) for smoothing the pulse voltage signal (S1). It is desirable that a configuration (second configuration) in which the on-duty of the pulse voltage signal (S1) is adjusted to adjust the value of the control current (S3) is desirable.

  According to such a configuration, the control current can be continuously adjusted only by adjusting the on-duty of the pulse voltage signal (S1). Therefore, even when a large number of control current adjustment levels are provided, the hardware configuration of the adjustment unit Becomes easier.

  In the overcurrent detection circuit of the second configuration, it is desirable that the adjustment unit includes a resistor (third configuration) provided between the smoothing circuit and a control terminal of the current-driven transistor. .

  According to such a configuration, the control current can be reliably generated.

  The air conditioner described above includes a printed circuit board (108), a printed circuit board support (109) for supporting the printed circuit board (108), and the printed circuit board (108) as the printed circuit board support (109). And detecting whether or not a predetermined one (115, 116) of the plurality of screws is removed, and detecting a predetermined one (115, 116) of the plurality of screws. ) Is a configuration (fourth configuration) including a control unit (117) that switches on / off of the forced operation according to whether or not it is removed.

  According to such a configuration, the forced operation is switched on / off depending on whether or not a predetermined one of the plurality of screws for fixing the printed circuit board to the printed circuit board support is removed. One of them also serves as a switch for switching on / off of forced operation. Thus, forced operation can be performed at low cost.

  In the air conditioner having the fourth configuration, the printed circuit board (108) includes a first conductive pattern (110) and a second conductive pattern (111), and the first conductive pattern (110 ), A detection terminal of the control unit (117) is connected to the second conductive pattern (111), and a predetermined one (115, 116) of the plurality of screws. Is not removed, the first conductive pattern (110) and the second conductive pattern (111) are electrically connected via a predetermined one (115, 116) of the plurality of screws. When a predetermined one (115, 116) of the plurality of screws is removed, the first conductive pattern (110) and the second conductive pattern (111) are electrically connected. Not configured ( It is desirable that the 5 configuration).

  According to such a configuration, the control unit can switch on / off of the forced operation based on the voltage applied to the detection terminal.

  In the air conditioner having the fifth configuration, the printed circuit board (108) includes a first conductor (112) provided on an end of the first conductive pattern (110), and the first conductive A second conductor (113) provided on an end of the pattern (110), and when a predetermined one (115, 116) of the plurality of screws is not removed, It is desirable that a predetermined one head (115) of the screws is in contact with the first conductor (112) and the second conductor (113) (sixth structure).

  According to such a configuration, the electrical connection between the predetermined one head of the plurality of screws and the first conductive pattern and the second conductive pattern is strengthened by the first conductor and the second conductor. can do.

  The thermistor mounting structure described above includes a thermistor (127), a compressor, a terminal cover member (124) that covers a terminal (121) protruding from the upper surface (120) of the compressor, and the terminal. A bolt (123) for fixing a cover member (124) to the compressor, and the thermistor (127) includes a temperature sensing part (128) and a fixing part (through hole (129) formed). 130) and a connecting part (131) for connecting the temperature sensing part (128) and the fixing part (130), the bolt (123) passes through the through hole (129), and the bolt In the state where the thermistor (127) is fixed to the compressor by (123) and the thermistor (127) is fixed to the compressor, the temperature sensing part (128) is located above the compressor. A structure in contact with the (120) (seventh configuration).

  According to such a configuration, the thermistor can be fixed to the compressor using the bolts for fixing the terminal cover member to the compressor in a state where the temperature sensing portion of the thermistor is in contact with the upper surface of the compressor. As a result, a compression with a large temperature difference from the temperature of the winding provided in the compressor when the stator winding of the motor mounted in the compressor is energized without circulating refrigerant. Since the temperature of the upper surface of the compressor with a small temperature difference is detected instead of the temperature of the discharge pipe of the machine, the temperature of the winding provided in the compressor can be detected with high accuracy.

  In the seventh thermistor mounting structure, the temperature sensing part (128) is connected to the fixing part (130) by the connecting part (131) and the exterior part (132). It is desirable to adopt a configuration (eighth configuration) having an interior portion (133) that can be attached to and detached from the bracket.

  According to such a configuration, since a conventional thermistor can be used for the interior portion, cost reduction can be achieved.

  Further, the electric device described above includes at least one attachment structure of the overcurrent detection circuit having any one of the first to third configurations and the thermistor having any one of the seventh to eighth configurations (first). 9).

102, 117 microcomputer 103 inverter control circuit 108 printed circuit board 109 electrical box 110 first copper foil pattern 111 second copper foil pattern 112 first solder layer 113 second solder layer 115 screw head 116 screw shaft Part 118 Detection terminal 120 Compressor upper surface 121 Terminal 123 Bolt 124 Terminal cover member 127 Thermistor 128 Temperature sensing part 129 Through hole 130 Fixing part 131 Connection part 132 Exterior part 133 Interior part C2 Capacitor Q1 Current-driven NPN bipolar transistor R1 Resistance

Claims (2)

A current-driven transistor provided on the conductor line;
An adjustment unit for adjusting the value of the control current supplied to the control terminal of the current-driven transistor,
Detecting an overcurrent flowing through the conductor line based on a voltage between the first terminal and the second terminal of the current-driven transistor ;
The adjustment unit includes a pulse circuit that outputs a pulse voltage signal and a smoothing circuit that smoothes the pulse voltage signal, and the on-duty of the pulse voltage signal is between the first terminal and the second terminal of the current-driven transistor. An overcurrent detection circuit, wherein the value of the control current is adjusted independently of a voltage . The overcurrent detection circuit according to claim 1, wherein the adjustment unit includes a resistor provided between the smoothing circuit and a control terminal of the current-driven transistor.

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