JP6171902B2 - Temperature detection device - Google Patents

Description

  The present invention relates to a temperature detection device that detects the temperature of a temperature detection target based on the potential of a temperature detection element with respect to a reference potential.

  Since power converters such as inverters and DCDC converters generate heat during power conversion, it is necessary to perform temperature management. Here, since it is not easy to directly detect the internal temperature of the power conversion device, the temperature detection element in which the potential between the terminals changes according to the temperature is fixed to the casing or heat sink of the power conversion device, and the temperature detection element In general, the temperature management is performed by using the temperature of the casing and the heat sink detected by the temperature as the temperature of the power converter.

  Usually, this detection method requires an operation process for fixing the temperature detection element to the housing or the heat sink, and an operation process for wiring the temperature detection element and the temperature detection circuit mounted on the circuit board. Furthermore, there are various problems such as complicated wiring.

  In view of this, a technique for solving the above-described mounting problems by bringing the conductor layer pattern of the circuit board into close contact with the heat sink and directly connecting the terminal of the temperature detection element mounted on the circuit board to the conductor layer pattern is proposed. (See Patent Document 1).

Japanese Patent No. 4048439

  Here, in the technique described in Patent Document 1, the ground terminal of the temperature detection element and the ground terminal of the temperature detection circuit are electrically connected via a conductor layer pattern and a heat sink. For this reason, the heat sink as the temperature detection target acts as a wiring resistance, and a potential difference occurs between the potential of the ground terminal of the temperature detection terminal and the potential of the ground terminal (input terminal) of the temperature detection circuit. An error may occur in the temperature to be detected.

  The present invention has been made in view of the above-mentioned problems, while favorably transferring the heat of the temperature detection target to the temperature detection element, and the input terminal of the temperature detection circuit to which the terminal is connected. It is an object of the present invention to provide a temperature detection device capable of suppressing temperature detection errors caused by a potential difference generated between the two.

  The invention according to claim 1 is a circuit board (10) fixed to a temperature detection target (20), and is mounted on the circuit board, and corresponds to the first terminal (X) according to the temperature of the temperature detection target. The temperature detection element (R1) in which the potential of the second terminal (Y) changes, and the first terminal and the second terminal of the temperature detection element are the first input terminal (V−) and the second input terminal (V +). A temperature detection circuit (40) for detecting the temperature of the temperature detection target based on a potential of the second input terminal with respect to the first input terminal, the first input terminal being connected to a reference potential, The circuit board includes: a first conductor layer (11a to 11d) that is in close contact with the temperature detection target; and a second conductor layer (14a) to which the first terminal is electrically connected. The first conductor layer and the second conductor The layers in the circuit board, along with being insulated, provided near the first terminal is characterized by being electrically connected to said first input terminal of the temperature detecting circuit.

  When the first conductor layer is in close contact with the temperature detection target, the heat of the temperature detection target is conducted to the first conductor layer. Furthermore, by providing the first conductor layer and the second conductor layer to which the temperature detection element is connected in proximity to each other, the heat conducted from the temperature detection target to the conductor layer is conducted to the temperature detection element. For this reason, since the temperature of the temperature detection element becomes substantially equal to the temperature of the temperature detection target, the temperature of the temperature detection target can be suitably detected.

  Here, assuming that the first terminal of the temperature detection element and the temperature detection target are electrically connected via the first conductor layer, the first terminal of the temperature detection element is changed by changing the potential of the temperature detection target. And a potential of the first input terminal of the temperature detection circuit to which the first terminal is connected (reference potential of the temperature detection circuit) may occur. In the present invention, the second conductor layer to which the first terminal of the temperature detection element is connected and the first conductor layer are insulated from each other on the circuit board, so that the temperature detection can be performed by changing the potential of the temperature detection target. The influence on the potential of the first terminal of the element is suppressed.

  Further, the first terminal of the temperature detection element and the first input terminal of the temperature detection circuit are electrically connected to each other, so that the first terminal of the temperature detection element and the first input terminal of the temperature detection circuit (temperature detection). The reference potential of the circuit) is set to an equipotential, and the potential of the second terminal with respect to the reference potential of the temperature detection circuit can be accurately detected. That is, it is possible to suppress a temperature detection error caused by a potential difference generated between the first terminal of the temperature detection element and the first input terminal of the temperature detection circuit to which the first terminal is connected.

The electrical block diagram of a charging device. The schematic sectional drawing of a charging device. The electrical block diagram of a temperature detection apparatus. The bottom view of a circuit board. The schematic sectional drawing of the charging device in a modification. The schematic sectional drawing of the charging device in a modification. The schematic sectional drawing of the charging device in a modification. The schematic sectional drawing of the charging device in a modification. The bottom view of the circuit board in a modification. The bottom view of the circuit board in a modification. The bottom view of the circuit board in a modification. The bottom view of the circuit board in a modification. The schematic sectional drawing of the circuit board in a modification.

  The temperature detection device according to the present embodiment detects the temperature of an exterior case that houses the charging device as a temperature detection target based on the potential of a thermistor as a temperature detection element with respect to a reference potential of the temperature detection circuit.

  The charging device A is constituted by a DCDC converter as shown in FIG. 1, and includes a battery B, an input side smoothing capacitor Ca, an inverter power MOS transistor 30, a step-up transformer T, a diode bridge type rectifier circuit D, and a choke coil. L, an output side smoothing capacitor Cb, a current detecting resistor element Ri, a control circuit M, a temperature detecting circuit 40, and a thermistor R1. The temperature detection circuit 40 and the thermistor R1 constitute a temperature detection circuit.

  By alternately turning on the power MOS transistors 30, an AC voltage is generated in the secondary coil of the step-up transformer T. This AC voltage is rectified by the rectifier circuit D and smoothed by the choke coil L and the output side smoothing capacitor Cb. Is output. The control circuit M normally controls the duty ratio of the power MOS transistor 30 so that the voltage drop of the current detection resistor element Ri is constant. Furthermore, when the control circuit M detects an excessive increase in the temperature of the power MOS transistor 30 based on the output voltage level of the temperature detection circuit 40, the control circuit M decreases the duty ratio of the power MOS transistor 30. The control circuit M prohibits energization of the power MOS transistor 30 when it is determined that the temperature of the power MOS transistor 30 has exceeded a predetermined value. By adopting such a configuration, it is possible to suppress the occurrence of an abnormality associated with an excessive increase in the temperature of the power MOS transistor 30. In addition, since this kind of charging device A is a known structure, description is abbreviate | omitted.

  FIG. 2 shows a schematic cross-sectional view of the charging device A in the present embodiment.

  An element constituting the DCDC converter, for example, a power MOS transistor 30 is fixed to the outer case 20. The power MOS transistor 30 and the outer case 20 are provided in surface contact. The exterior case 20 is provided with a support portion 21 that supports the circuit board 10. The support portion 21 is a rectangular frame-like member that stands up toward the inside of the case. The support portion 21 and the power MOS transistor 30 are provided close to each other. The support portion may be composed of a plurality of columnar (columnar or prismatic) members.

  The circuit board 10 insulates the conductor layers 11a to 11c and the conductor layers 11a to 11c and a plurality of conductor layers (not shown) that transmit signals or power to the elements mounted on the surface of the circuit board 10. And an insulating layer 12. The conductor layers 11a to 11c are made of metal such as copper foil, and the insulating layer 12 is made of resin such as glass epoxy. The circuit board 10 is provided with through holes 13 penetrating both surfaces thereof. The through hole 13 functions as a conductor that conducts electricity and heat by being covered with copper foil. The through hole 13 is connected to conductor layers 11 a and 11 b formed on both surfaces of the circuit board 10 and a conductor layer 11 c as an internal conductor layer formed inside the circuit board 10. That is, the conductor layers 11 a to 11 c are configured to be electrically connected to each other and thermally conducted to each other by the conductor provided in the through hole 13.

  A thermistor R <b> 1 that detects the temperature of the outer case 20 is mounted on the surface of the outer case 20 on the circuit board 10. The temperature detection circuit 40 that detects the temperature of the outer case 20 and thus the temperature of the power MOS transistor 30 is mounted on a substrate 42 different from the circuit substrate 10.

  The circuit board 10 is placed on the top surface of the support portion 21, and the screw 22 passes through the through hole 13 and is screwed into the support portion 21, so that the circuit board 10 is fixed to the exterior case 20. Here, the inner diameter of the through hole 13 is smaller than the outer diameter of the support portion 21, and the conductor layer 11 a as the surface conductor layer formed on the surface of the circuit board 10 on the exterior case 20 side and the support portion 21 are surfaces. It has a structure that comes into contact and close contact. Thereby, heat is conducted from the support portion 21 to the conductor layer 11a. Further, the screw 22 and the conductor layer 11b are in surface contact with each other, and heat is conducted from the support portion 21 to the conductor layer 11b via the screw 22. Further, the inner diameter of the through hole 13 and the outer diameter of the screw 22 are substantially equal to each other. When the through hole 13 and the screw 22 are in contact with each other, the through hole 13 is provided in the through hole 13 via the screw 22. Heat is conducted to the conductor. The conductors provided in the conductor layers 11a to 11c and the through hole 13 function as a first conductor layer that is in close contact with the outer case 20 as a temperature detection target.

  The outer case 20 is made of a metal having high thermal conductivity (for example, aluminum), and heat generated in the power MOS transistor 30 is quickly conducted to the outer case 20. The outer case 20 is cooled by water cooling or air cooling. The heat conducted to the exterior case 20 is conducted to the thermistor R1 through the support portion 21 and the conductor layers 11a to 11c. Since the power MOS transistor 30 and the support portion 21 are provided close to each other, the temperatures of the power MOS transistor 30 and the thermistor R1 are substantially equal. The temperature detection circuit 40 detects the temperature of the outer case 20 and thus the temperature of the power MOS transistor 30 based on the potential of the output terminal Y as the second terminal with respect to the ground terminal X as the first terminal of the thermistor R1. Can do.

  FIG. 3 shows an electrical configuration diagram of the temperature detection device in the present embodiment.

  Resistor R2 and thermistor R1 form a voltage dividing circuit. Specifically, one terminal of the resistor R2 is connected to the constant voltage power supply Vcc, and the other terminal is connected to the output terminal Y of the thermistor R1. The output terminal Y of the thermistor R1 is connected to the V + terminal which is the second input terminal of the non-inverting amplifier circuit 41. Further, the V− terminal which is the first input terminal of the non-inverting amplifier circuit 41 is connected to the ground terminal Z of the temperature detection circuit 40. The output terminal Vout of the non-inverting amplifier circuit 41 is connected to the control circuit M.

  The thermistor R1 is, for example, an NTC (Negative Temperature Coefficient) thermistor, and its resistance decreases as the temperature rises. That is, as the temperature increases, the output voltage of the non-inverting amplifier circuit 41 decreases. Based on the output voltage of the non-inverting amplifier circuit 41, the control circuit M can acquire the temperature of the thermistor R1 using the temperature-resistance characteristic of the thermistor R1.

  Here, it is assumed that the ground terminal X of the thermistor R1 and the outer case 20 are connected via the conductor layer 11a. Since the ground terminal Z of the temperature detection circuit 40 is connected to the exterior case 20, the ground terminal Z of the temperature detection circuit 40 and the ground terminal X of the thermistor R1 are connected via a current path on the exterior case 20. . Here, when a current such as a noise current flows through the current path on the exterior case 20, the potential Va at the location where the ground terminal X of the thermistor R1 is connected to the ground terminal Z of the temperature detection circuit 40 in the exterior case 20. A potential difference is generated between the potential Vb of the connected portions. Due to the potential difference ΔV between the potential Va and the potential Vb, an error may occur when detecting the potential of the output terminal Y with respect to the ground terminal X of the thermistor R1. The potential detection error may cause an error in temperature detection by the temperature detection circuit 40.

  Therefore, in the temperature detection circuit according to the present embodiment, the insulating layer 12 is provided between the ground terminal X of the thermistor R1 and the outer case 20 so as to conduct heat and not be electrically connected. Then, the ground terminal X of the thermistor R1 and the ground terminal Z of the temperature detection circuit 40 are connected using a conductor layer and a conductive wire having a resistance value lower than that of the current path on the exterior case 20. As a result, the influence of the potential difference ΔV can be suppressed. Note that the potential of the ground terminal Z of the temperature detection circuit 40 can be stabilized by inserting a filter composed of a capacitor or the like between the ground terminal Z and the outer case 20.

  Specifically, as shown in FIG. 2, the conductor layer 14 a (first conductor layer) to which the ground terminal X of the thermistor R <b> 1 is connected and the conductor layers 11 a to 11 c (that is, the exterior case 20) are connected to the circuit board 10. The insulating layer 12 is electrically insulated, and the conductor layer 14a to which the thermistor R1 is connected and the conductor layers 11a to 11c (second conductor layers) are provided close to each other. Thereby, it can be set as the structure which heat conducts suitably, insulating between the thermistor R1 and the exterior case 20. FIG.

  FIG. 4 shows a bottom view of the surface of the circuit board 10 as viewed from the exterior case 20 side. An annular conductor layer is provided so as to surround the two through holes 13, and a strip-like conductor layer is provided so as to connect the annular conductor layer, and these conductor layers form the conductor layer 11 a. It is composed. The conductor layer 11a, the conductor layer 14a to which the ground terminal X of the thermistor R1 is connected, and the conductor layer 14b to which the output terminal Y is connected are provided on the same plane. A gap G is provided between the conductor layer 11a and the conductor layers 14a and 14b. Here, by reducing the gap G, the thermal resistance between the conductor layer 11a and the thermistor R1 is reduced.

  Returning to the description of FIG. 2, the conductor layer 11 a and the through hole 13 are connected, and the conductor layer 11 c is provided inside the circuit board 10 so as to be laminated on the conductor layer 14 a. The conductor layer 11 c is connected to the conductor layer 11 a through the through hole 13. Further, the conductor layer 11c is provided near the surface on which the thermistor R1 is mounted so that the conductor layer 11c and the thermistor R1 conduct heat through the insulating layer 12. The conductor layer 11c is extended to a position facing the conductor layers 14a and 14b. Further, the conductor layer 11a and the conductor layer 11c are arranged so as to face each other. As described above, the heat of the outer case 20 is suitably conducted to the thermistor R1, and the temperature of the thermistor R1 and the temperature of the outer case 20 become substantially equal.

  Regarding electrical connection, the ground terminal X of the thermistor R <b> 1 is connected to the conductor layer 17 through the conductor layer 14 a and the via 16. Here, the via 16 and the conductor layers 11a to 11c are provided so as not to be electrically connected. The conductor layer 17 is connected to the connector 15. The connector 15 of the circuit board 10 and the connector 43 of the temperature detection circuit 40 are connected via a conducting wire 60. The connector 43 is connected to the ground terminal Z of the temperature detection circuit 40 and the V-terminal of the non-inverting amplifier circuit 41. Further, the output terminal Y of the thermistor R1 and the V + terminal of the non-inverting amplifier circuit 41 are connected via the conductor layer 14b, the connector 15 and the conducting wire 60. That is, the conducting wire 60 includes two connection lines, a connection line that connects the ground terminal X and the V− terminal, and a connection line that connects the output terminal Y and the V + terminal. In FIG. 2, the connection between the conductor layer 14b to which the output terminal Y is connected and the connector 15 is not shown.

  Here, the resistance values of the conductor layer 14a, the via 16, the conductor layer 17, the connector 15, the conductive wire 60, and the connector 43 are sufficiently smaller than the current path on the exterior case 20, and the temperature detection is performed with the ground terminal X of the thermistor R1. The ground terminal Z of the circuit 40 becomes equipotential. Thereby, when detecting the potential of the output terminal Y with respect to the ground terminal X of the thermistor R1, the exterior Va to which the potential Va of the exterior case 20 near the ground terminal X of the thermistor R1 and the ground terminal Z of the temperature detection circuit 40 are connected. It is possible to suppress the influence of the potential difference ΔV with respect to the potential Vb of the case 20. That is, the temperature detection circuit 40 can accurately detect the temperature of the thermistor R1.

  Hereinafter, the operational effects of the present embodiment will be described.

  When the support portion 21 which is a part of the outer case 20 is in close contact with the conductor layer 11a of the circuit board 10, heat of the outer case 20 is conducted to the conductor layer 11a. Further, by adopting a configuration in which the conductor layer 11a and the thermistor R1 conduct heat, the heat conducted from the outer case 20 to the conductor layer 11a is conducted to the thermistor R1. For this reason, the temperature of the thermistor R1 becomes substantially equal to the temperature of the exterior case 20, and the temperature of the exterior case 20 and thus the temperature of the power MOS transistor 30 can be suitably detected.

  Here, if the ground terminal X of the thermistor R1 is electrically connected to the outer case 20 via the conductor layers 11a to 11c, the potential of the ground terminal X of the thermistor R1 is There is a possibility that a potential difference may be generated between the temperature detection circuit 40 and the ground terminal Z. In the present embodiment, since the ground terminal X of the thermistor R1 and the conductor layers 11a to 11c are not electrically connected, the influence of the potential of the exterior case 20 on the potential of the ground terminal X of the thermistor R1 is affected. Suppress. Further, the ground terminal X of the thermistor R1 and the ground terminal Z of the temperature detection circuit 40 are electrically connected, so that the ground terminal X of the thermistor R1 and the ground terminal Z of the temperature detection circuit 40 have the same potential, and the thermistor It is possible to accurately detect the potential of the output terminal Y with respect to the ground terminal Z of R1. That is, it is possible to suppress a temperature detection error caused by the difference between the potential of the ground terminal X of the thermistor R1 and the potential of the ground terminal Z of the temperature detection circuit 40.

  The thermistor R1 and the conductor layer 11a are configured to conduct heat through the insulating layer 12 of the circuit board 10. With this configuration, temperature detection using the thermistor R1 can be suitably performed while avoiding electrical connection between the thermistor R1 and the conductor layer 11a.

  A conductor layer 11a as a first conductor layer is provided on the surface of the circuit board 10, and a conductor layer 14a as a second conductor layer is provided on the same plane as the conductor layer 11a. As shown in FIG. 4, the conductor layer 11a is disposed so as to surround the conductor layer 14a. With this configuration, it is possible to suitably conduct the heat of the outer case 20 as a temperature detection target to the thermistor R1 while insulating the ground terminal X of the thermistor R1 from the outer case 20.

  Also, a conductor layer 11c as a first conductor layer is provided inside the circuit board 10 so as to be laminated with a conductor layer 14a as a second conductor layer, and the conductor layer 11c is disposed so as to face the conductor layer 14a. Yes. With this configuration, it is possible to suitably conduct the heat of the outer case 20 as a temperature detection target to the thermistor R1 while insulating the ground terminal X of the thermistor R1 from the outer case 20. The conductor layer 11c may be disposed so as to face all of the conductor layer 14a, or may be disposed so as to face a part of the conductor layer 14a.

  Further, as the first conductor layer, a surface conductor layer (conductor layer 11a) is provided so as to surround the conductor layer 14a in the same plane as the conductor layer 14a, and is laminated with the conductor layer 14a inside the circuit board 10 to form an internal conductor. A layer (conductor layer 11c) is provided. The conductor layer 11a and the conductor layer 11c are disposed so as to face each other. With this arrangement, it is possible to suitably conduct heat between the conductor layer 11a and the conductor layer 11c. That is, heat can be conducted from the conductor layer 11c to the conductor layer 11a in the vicinity of the conductor layer 14a, and further, heat can be conducted from the conductor layer 11a in the vicinity of the conductor layer 14a to the conductor layer 14a and the thermistor R1. For this reason, it becomes possible to transmit the heat | fever of the exterior case 20 to the thermistor R1 suitably. The conductor layer 11c may be disposed so as to face all of the conductor layer 11a, or may be disposed so as to face a part of the conductor layer 11a.

  The conductor layer 11a is in close contact with the top surface of the support portion 21 that is a part of the outer case 20 that is a temperature detection target. Thereby, the heat of the exterior case 20 is quickly conducted to the conductor layer 11a.

  In particular, in the present embodiment, the conductor layer 11a is provided so as to be in close contact with the top surfaces of the plurality of support portions 21, thereby increasing the area in which the conductor layer 11a and the outer case 20 are in close contact with each other. Yes. Thereby, heat can be suitably conducted from the outer case 20 to the conductor layer 11a.

  Both the circuit board 10 and the temperature detection circuit 40 are supported by the exterior case 20. Here, the ground terminal X of the thermistor R <b> 1 and the ground terminal Z of the temperature detection circuit 40 are connected via the conductor layer 17 and the conductive wire 60. Since the conductor layer 17 and the conductive wire 60 are members having lower electrical resistance than the exterior case 20, the ground terminal X of the thermistor R <b> 1 and the ground terminal Z of the temperature detection circuit 40 are connected via the exterior case 20. In comparison with this, the potential difference between the potential of the ground terminal X and the potential of the ground terminal Z can be reduced.

(Other embodiments)
As shown in FIG. 5, the conductor layer 11a and the conductor layer 14a to which the ground terminal X of the thermistor R1 is connected are electrically connected via the resistor R3, and heat is conducted via the resistor R3. It is good also as composition to do. The conductor layer 14a to which the ground terminal X of the thermistor R1 is connected and the conductor layer 11a are directly electrically connected to each other to avoid the equipotential, and the thermal conductivity between the thermistor R1 and the outer case 20 is improved. Can be made. In addition, the conductor layer 14b to which the output terminal Y of the thermistor R1 is connected and the conductor layer 11a may be connected via a resistor R4. The resistance values of the resistors R3 and R4 may be larger than the resistance value of the thermistor R1.

  Instead of the resistor R3, the conductor layer 14a to which the ground terminal X of the thermistor R1 is connected via a capacitor may be electrically connected to the conductor layer 11a, and heat may be conducted via the capacitor. The thermal conductivity between the thermistor R1 and the outer case 20 can be improved while DC-insulating the ground terminal X of the thermistor R1 and the conductor layer 11a.

  In the above embodiment, the circuit board 10 on which the thermistor R1 is mounted and the temperature detection circuit 40 are supported (accommodated) by the same exterior case 20, but instead of this configuration, the circuit The substrate 10 and the temperature detection circuit 40 may be supported by different exterior cases. In this case, if the outer cases are insulated, a potential difference is generated between the potential Va of the ground terminal X of the thermistor R1 and the potential Vb of the ground terminal Z of the temperature detection circuit 40. In this case, the ground terminal X of the thermistor R1 and the ground terminal Z of the temperature detection circuit 40 are connected via the lead wire 60, whereby the potential Va of the thermistor R1 and the ground terminal Z of the temperature detection circuit 40 are connected. It is possible to suppress a temperature detection error caused by the difference from the potential Vb. That is, even when the thermistor R1 and the temperature detection circuit 40 are provided apart from each other, it is possible to detect the temperature suitably.

  In the above embodiment, the temperature detection circuit 40 is provided separately from the circuit board 10, but instead of this configuration, the temperature detection circuit 40 is provided on the circuit board 10 as shown in FIG. 40 may be provided. In this case, by connecting the ground terminal X of the thermistor R1 and the ground terminal Z of the temperature detection circuit 40 via the conductor layer 14a, the via 16 and the conductor layer 17 of the circuit board 10, the potential of the ground terminal X of the thermistor R1. And the potential of the ground terminal Z of the temperature detection circuit 40 can be made equipotential.

  As shown in FIG. 7, a footprint 11 d as a first conductor layer is provided on the surface of the circuit board 10 on the exterior case 20 side, and an insulating portion IS covered with an insulator of the footprint 11 d and the thermistor R <b> 1. Place them so that they touch. Further, the footprint 11d and the conductor layer 11c inside the circuit board 10 are connected by a via 11e. With this configuration, heat is conducted between the conductor layer 11c and the thermistor R1 through the footprint 11d and the via 11e, so that the temperature of the outer case 20 can be detected more accurately. In addition, by providing the terminals X and Y of the thermistor R1 and the footprint 11d so as not to contact each other, a configuration in which the thermistor R1 and the conductor layers 11a to 11c are insulated can be maintained.

  In the above embodiment, the power MOS transistor 30 and the support portion 21 are brought close to each other, and consequently, the power MOS transistor 30 and the thermistor R1 are brought close to each other. Instead of this, a heating element such as the power MOS transistor 30 and the support portion 21 may be provided separately. In this case, the temperature of the thermistor R <b> 1 is substantially equal to the temperature of the outer case 20 and consequently the temperature of the refrigerant that cools the outer case 20. Here, the temperature of the refrigerant that cools the outer case 20 is the temperature of the cooling air that cools the outer case 20 when the outer case 20 is air-cooled, and the outer case 20 is cooled when the outer case 20 is water-cooled. It is the temperature of the cooling water.

  Further, the control circuit M detects the temperature of these refrigerants by detecting the potential of the output terminal Y with respect to the ground terminal X of the thermistor R1, and reduces the duty ratio of the power MOS transistor 30 based on the detected temperature. To do. The control circuit M is configured to prohibit energization of the power MOS transistor 30 when it is determined that the detected temperature of the refrigerant has exceeded a predetermined value. With this configuration, it is possible to suppress an excessive increase in the temperature of the power MOS transistor 30 caused by an excessive increase in the temperature of the refrigerant.

  -Although it was set as the structure which closely_contact | adheres the support part 21 of the exterior case 20, and the conductor layer 11a of the circuit board 10 using the screw 22, it replaces with this and adheres the support part 21 and the conductor layer 11a of the circuit board 10 with a spring. A configuration may be adopted.

  -Although it was set as the structure which closely_contact | adheres the support part 21 of the exterior case 20, and the conductor layer 11a of the circuit board 10, it replaces with this, metal springs, heat conduction grease, etc. between the support part 21 and the conductor layer 11a It is good also as a structure which inserts a member with high thermal conductivity.

  Although the conductor layer 11c is provided inside the circuit board 10, this may be omitted and the conductor layers 11a and 11b may be provided only on the surface of the circuit board 10. By omitting the conductor layer 11c inside the circuit board 10, the manufacturing cost can be reduced. In addition, a plurality of conductor layers 11 c may be provided inside the circuit board 10. With this configuration, the thermal conductivity from the conductor layers 11a to 11c to the thermistor R1 can be improved.

  -As shown in FIG. 8, the footprint 11d as a 1st conductor layer is provided in the position which contact | connects the insulation part IS of the thermistor R1. A plurality of conductor layers 11 c are provided inside the circuit board 10. And the thermal conductivity from conductor layer 11a-11c to the thermistor R1 can be improved by connecting footprint 11d and the some conductor layer 11c by the via | veer 11e.

  Although the thermistor R1 is used as the temperature detection element, instead of this, a temperature-sensitive diode whose forward drop voltage changes with temperature, a temperature measuring resistor whose resistance value changes with temperature, or the like may be used.

  FIG. 9 shows a bottom view of the surface of the circuit board 10 in the modification as seen from the exterior case 20 side. Three through-holes 13 are provided, an annular conductor layer is provided so as to surround the through-hole 13, and a strip-like conductor layer is provided so as to connect the annular conductor layers. This constitutes the layer 11a. With this configuration, the contact area between the conductor layer 11a and the support portion 21 can be increased, and the thermal conductivity between the support portion 21 and the conductor layer 11a can be improved. Further, while providing a gap G between the conductor layer 11a and the conductor layers 14a and 14b to which the ground terminal X and the output terminal Y of the thermistor R1 are connected, the conductor layer 11a is surrounded by the conductor layers 14a and 14b. Provided. With this configuration, the thermal conductivity between the conductor layer 11a and the thermistor R1 can be improved.

  FIG. 10 shows a bottom view of the surface of the circuit board 10 in the modification as seen from the exterior case 20 side. A through-hole 13 is provided, an annular conductor layer is provided so as to surround the through-hole 13, a band-like conductor layer is provided from the annular conductor layer toward the thermistor R1, and these conductor layers form the conductor layer 11a. It is composed. Further, two rectangular windows are provided in the strip-shaped portion of the conductor layer 11a, and a conductor layer 14a and a conductor layer 14b are provided in each window. A gap G is provided between the conductor layers 14a and 14b and the conductor layer 11a. That is, the conductor layer 11a and the conductor layers 14a and 14b are provided on the same plane, and the conductor layer 11a is disposed so as to surround the conductor layers 14a and 14b.

  The conductor layer 14a is connected to the ground terminal X of the thermistor R1, and the conductor layer 14b is connected to the output terminal Y of the thermistor R1. With such an arrangement, heat can be suitably conducted from the conductor layer 11a to the thermistor R1. Furthermore, the insulating part IS of the thermistor R1 and the conductor layer 11a are arranged so as to contact each other. Heat can be suitably conducted from the conductor layer 11a to the thermistor R1 by the contact between the conductor layer 11a and the insulating part IS.

  FIG. 11 shows a bottom view of the surface of the circuit board 10 in the modification as seen from the exterior case 20 side. A through-hole 13 is provided, an annular conductor layer is provided so as to surround the through-hole 13, a band-like conductor layer is provided from the annular conductor layer toward the thermistor R1, and these conductor layers form the conductor layer 11a. It is composed. Here, in the conductor layer 11a, a strip-like portion is provided with a notch, and the conductor layer 14a and the conductor layer 14b are provided in the notch. A gap G is provided between the conductor layers 14a and 14b and the conductor layer 11a. That is, the conductor layer 11a and the conductor layers 14a and 14b are provided on the same plane, and the conductor layer 11a and the conductor layers 14a and 14b are disposed adjacent to each other. The conductor layer 14a is connected to the ground terminal X of the thermistor R1, and the conductor layer 14b is connected to the output terminal Y of the thermistor R1. With this arrangement, the conductor layer 11c and the conductor layer 14a are arranged close to each other while insulating the conductor layer 11a as the first conductor layer and the conductor layer 14a as the second conductor layer. Heat can be suitably transferred from 11a to the thermistor R1.

  FIG. 12 is a bottom view of the surface of the circuit board 10 in the modification as viewed from the exterior case 20 side. Two through holes 13 are provided, and an annular conductor layer 11 a is provided so as to surround the through holes 13. Conductor layers 14a and 14b are provided so as to be positioned between the two through holes 13, and the ground terminal X of the thermistor R1 is connected to the conductor layer 14a, and the output terminal Y of the thermistor R1 is connected to the conductor layer 14b. Further, as shown in FIG. 13, a conductor layer 11c is laminated on the conductor layers 14a and 14b via the insulating layer 12, and the conductor layer 11c is disposed so as to face the conductor layers 14a and 14b. Then, the conductor layer 11 a and the conductor layer 11 c are connected by a conductor provided in the through hole 13. With this configuration, the conductor layer 11c and the conductor layer 14a are disposed close to each other while the conductor layer 11c as the first conductor layer and the conductor layer 14a as the second conductor layer are insulated. Heat can be suitably conducted from 11c to the thermistor R1.

  In the above embodiment, the circuit board 10 is supported by the outer case 20 as a temperature detection target. Instead, the circuit board 10 is supported by a heat sink provided in a heating element such as the power MOS transistor 30. It may be. With this configuration, the heat sink can be a temperature detection target, and the power MOS transistor 30 and the like can be controlled based on the detected temperature.

  In the above embodiment, the first terminal X of the thermistor R1 is connected to the ground potential by being connected to the ground terminal Z of the temperature detection circuit 40, but instead, the first terminal X is connected to the ground potential. The terminal Z of the temperature detection circuit 40 to be connected may be connected to a predetermined voltage different from the ground potential.

  DESCRIPTION OF SYMBOLS 10 ... Circuit board, 20 ... Exterior case (temperature detection object), R1 ... Thermistor (temperature detection element), X ... Grounding terminal (first terminal), Y ... Output terminal (second terminal), 11a-11d ... Conductor layer (First conductor layer), 14a... Conductor layer (second conductor layer), 40... Temperature detection circuit.

Claims (6)

A circuit board (10) fixed to a temperature detection target (20);
A temperature detection element (R1) mounted on the circuit board, wherein the potential of the second terminal (Y) with respect to the first terminal (X) changes according to the temperature of the temperature detection target;
The first terminal and the second terminal of the temperature detecting element are connected to a first input terminal (V−) and a second input terminal (V +), respectively, the first input terminal is connected to a reference potential, In a temperature detection apparatus comprising: a temperature detection circuit (40) that detects a temperature of the temperature detection target based on a potential of the second input terminal with respect to one input terminal;
The circuit board includes a first conductor layer (11a to 11d) that is in close contact with the temperature detection target, and a second conductor layer (14a) to which the first terminal is electrically connected,
In the circuit board, the first conductor layer and the second conductor layer are insulated and provided close to each other,
The first terminal is electrically connected to the first input terminal of the temperature detection circuit ;
The temperature detection target includes a support portion (21) that is erected toward the circuit board and has a mounting surface on which the circuit board is mounted.
The first conductor layer is in close contact with the temperature detection target by being in close contact with the placement surface . In the circuit board, the first conductor layer and the second conductor layer are provided on the same plane,
The temperature detection device according to claim 1, wherein the first conductor layer is disposed adjacent to the second conductor layer or surrounds the entire second conductor layer. In the circuit board, the first conductor layer and the second conductor layer are provided by being laminated,
The temperature detection device according to claim 1, wherein the first conductor layer is disposed so as to face a part or all of the second conductor layer. In the circuit board, a plurality of the first conductor layers are provided,
The plurality of first conductor layers include a surface conductor layer (11a) provided on the same plane as the second conductor layer, and an inner conductor layer (11c) provided by being stacked on the second conductor layer. ,
The surface conductor layer is arranged adjacent to the second conductor layer or surrounding the entire second conductor layer,
The temperature detection device according to claim 1, wherein the inner conductor layer is disposed so as to face part or all of the surface conductor layer.   The temperature detecting device according to any one of claims 1 to 4, wherein the first conductor layer (11d) and the insulating portion (IS) of the temperature detecting element are in contact with each other. The temperature detection target includes a plurality of the support portions,
Wherein the first conductive layer, the temperature detection device according to any one of claims 1 to 5, characterized in that close contact with the temperature detected by close contact with each mounting surface of the plurality of support portions .

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