Electrical connection structure for temperature sensor

Abstract

Provided is an electrical connection structure for a temperature sensor whereby it is possible to suppress increases in costs due to the use of electric wire.　The electrical connection structure for a temperature sensor includes: a temperature sensor 1 that is attached to an object member 3 housed in a device case 6 and comprises a heat-sensitive element for detecting temperature and an external connection section 42 serving as a terminal for outputting an electric signal corresponding to the temperature detected by the heat-sensitive element; a connection port 6a that is provided to the device case 6 and can form an electrical connection between the exterior and the interior of the device case 6; and a relay bus bar 5 for electrically connecting the external connection section 42 and the connection port 6a. A path from the external connection section 42 to the connection port 6a is formed by means of the relay bus bar 5 without using any electric wire.

Description

Electrical Connection Structure for Temperature Sensor

[0001] The present disclosure relates to an electrical connection structure for a temperature sensor.

[0002] In some cases, a temperature sensor is attached to a member or device that generates heat during operation to monitor the temperature. For example, in a relay provided in a junction box that is mounted on an automobile and supplies electric power from a battery to various devices, heat generation during operation is a problem. Therefore, a temperature sensor may be attached to the relay or a related member to monitor heat generation of the relay. The temperature read by the temperature sensor is input to a control device such as an electronic control unit (ECU) and used for controlling the device. For example, Patent Document 1 discloses a configuration in which a temperature sensor for detecting heat generation of electrical components including a relay is provided on a bus bar connected to the relay in a junction box. The temperature sensor is configured as a member including, for example, a thermistor.

[0003] Patent Document 1 does not describe an electrical connection structure for extracting an electrical signal output from a temperature sensor to the outside of the junction box. However, usually, an electric wire connected to a built-in thermistor is attached to the temperature sensor. Then, the electric wire is appropriately relayed by another electric wire and connected to an external connection port provided in a case of the junction box. By connecting a connector from outside the junction box to the external connection port, the output of the temperature sensor can be extracted to the outside of the junction box and input to an external device such as an ECU.

[0004] International Publication No. 2021 / 059767

[0005] As described above, when a temperature sensor is installed inside a device such as a junction box, the output of the temperature sensor is usually taken out to the outside of the device via a wire. However, if a wire is attached to the temperature sensor, or if a wire is used as a relay between the temperature sensor and the port for external connection, then these wires will incur costs. Furthermore, due to factors such as the flexibility of the wire, transportation, assembly, and routing also incur significant costs. It is desirable to reduce these costs required for the manufacture and installation of temperature sensors.

[0006] In view of the above, the objective is to provide an electrical connection structure for a temperature sensor that can suppress the increase in costs caused by the use of electrical wires.

[0007] The electrical connection structure of the temperature sensor disclosed herein includes a temperature sensor attached to a target member housed in a device case, which has a thermal element for detecting temperature and an external connection part as a terminal for outputting an electrical signal corresponding to the temperature detected by the thermal element; a connection port provided in the device case and capable of forming an electrical connection inside and outside the device case; and a relay bus bar that electrically connects the external connection part and the connection port, wherein the path from the external connection part to the connection port is formed by the relay bus bar without using electric wires.

[0008] The electrical connection structure of the temperature sensor according to this disclosure makes it possible to suppress the increase in costs caused by the use of electric wires.

[0009] Figure 1 is a perspective view showing an electrical connection structure of a temperature sensor according to one embodiment of the present disclosure. Figure 2 is a perspective view showing an example of a temperature sensor used in the above electrical connection structure. The resin case and sealing resin are shown transparently, and the internal busbars are shown in gray. (The same applies to Figures 3 to 5B). Figure 3 is a plan view showing the above temperature sensor. Figure 4 is a side view showing the above temperature sensor. Figures 5A to 5C are schematic diagrams illustrating a method for fixing the heat-sensitive element to the resin case of the above temperature sensor. Each shows a different form. Figure 6 is an enlarged plan view showing a modified form of the temperature sensor.

[0010] [Description of Embodiments of the Disclosure] First, embodiments of the disclosure will be listed and described. The electrical connection structure of the temperature sensor according to the disclosure has the following configuration.

[0011] [1] The electrical connection structure of the temperature sensor according to the present disclosure includes a temperature sensor attached to a target member housed in a device case, which has a thermal element for detecting temperature and an external connection part as a terminal for outputting an electrical signal corresponding to the temperature detected by the thermal element; a connection port provided in the device case and capable of forming an electrical connection inside and outside the device case; and a relay bus bar that electrically connects the external connection part and the connection port, wherein the path from the external connection part to the connection port is formed by the relay bus bar without using electric wires.

[0012] In the electrical connection structure of the temperature sensor described above, the temperature sensor is equipped with an external connection part provided as a terminal, and the connection part and the connection port provided on the device case are connected via a busbar, without the use of wires. Unlike wires, the busbar is made of a rigid member made of continuous metal and does not have any covering material, so the material cost can be kept lower than that of wires. The costs required for transportation, assembly, and wiring are also reduced. Therefore, costs can be reduced compared to using wires to connect the temperature sensor and the connection port.

[0013] [2] In the embodiment of [1] above, the external connection portion may be connected to the intermediate bus bar via an external connection terminal, or by welding or soldering. In the electrical connection structure of the temperature sensor according to this embodiment, the electrical connection path between the temperature sensor and the connection port is formed by an intermediate bus bar which is a rigid member. By using an external connection terminal, or by welding or soldering, for the electrical connection between the external connection portion of the temperature sensor and the intermediate bus bar, the electrical connection can be constructed simply and stably while keeping costs down.

[0014] [3] In the embodiment of [2] above, the external connection terminal may be a tuning fork terminal or an FF terminal. This makes it possible to construct the electrical connection between the external connection part of the temperature sensor and the relay busbar in a particularly simple and stable manner.

[0015] [4] In any of the embodiments of [1] to [3] above, the temperature sensor comprises a heat-sensitive element, a resin case housing the heat-sensitive element, and an internal busbar held in the resin case, wherein a region including one end of the internal busbar is an internal connection portion connected to the output portion of the heat-sensitive element that outputs an electrical signal corresponding to the temperature, and a region including the other end of the internal busbar protrudes to the outside of the resin case and forms the external connection portion. In this case, not only the electrical connection between the external connection portion and the connection port of the temperature sensor, but also the internal electrical connection of the temperature sensor is constructed using a busbar instead of wires, thus achieving an even greater cost reduction. Furthermore, since the portion of the internal busbar that protrudes from the resin case can be used as the external connection portion, a temperature sensor having an external connection portion can be manufactured with a simple configuration.

[0016] [5] In the embodiment of [4] above, the temperature sensor may further be provided with a fixing terminal in contact with at least a part of the resin case, and fixed to the target member by the fixing terminal. In this case, the temperature sensor can be easily attached to the target member by using the fixing terminal. In addition, since heat transfer from the target member to the heat-sensitive element occurs with high efficiency via the fixing terminal and the resin case, the accuracy of temperature detection by the temperature sensor can be improved.

[0017] [6] In any of the embodiments described in [1] to [5] above, the target member may be an electrical component that is housed inside the case of the automotive junction box as the device case and generates heat when in operation, or a member coupled to the electrical component. The case of the automotive junction box contains electrical components that generate heat when in operation, such as relays, and the heat generated by these components is a common problem. However, by attaching temperature sensors to these electrical components, or to members such as busbars coupled to these electrical components, and providing the electrical connection structure according to this embodiment, a system for monitoring the heat generated by electrical components can be constructed while keeping costs down.

[0018] [Details of Embodiments of the Disclosure] Below, an electrical connection structure of a temperature sensor according to one embodiment of the Disclosure will be described in detail with reference to the drawings. In this specification, terms indicating the shape and arrangement of members, such as "parallel" and "alongside," include not only geometrically precise concepts but also errors within the generally acceptable range for temperature sensors and electrical connection members, such as deviations of approximately ±15% in length and approximately ±15° in angle.

[0019] <Electrical Connection Structure of Temperature Sensor> Figure 1 shows an electrical connection structure of a temperature sensor according to one embodiment of the present disclosure (hereinafter sometimes simply referred to as the electrical connection structure). The electrical connection structure according to this embodiment relates to an electrical connection for taking the output of a temperature sensor to the outside of a device when the temperature sensor is attached to a target component provided inside the device.

[0020] The target component is a component whose temperature is to be detected, preferably an electrical component that generates heat during operation, or a component coupled to such a heat-generating electrical component. The type of target component and the type of device on which the target component is installed are not particularly limited. However, in the configuration shown in Figure 1, an automobile junction box 7 is used as the device. The busbar (relay busbar) 3 connected to a relay 2 installed inside the junction box 7 is used as the target component. A temperature sensor 1 is attached to the relay busbar 3, which is the target component. Due to the heat generated when the relay 2 operates, the relay busbar 3 becomes hot, and the temperature of the relay busbar 3 is detected by the temperature sensor 1. Alternatively, the relay 2 itself may be used as the target component, and the temperature sensor may be directly attached to the relay 2. In addition to relays, other electrical components installed inside the automobile junction box 7 that generate heat during operation include fuses and pyrofuses, and these electrical components, or components such as busbars coupled to these electrical components, can also be suitably applied as target components.

[0021] The components constituting the electrical connection structure according to this embodiment include a temperature sensor 1, a relay bus bar 5, and a connection port 6a. The electrical connection between the temperature sensor 1 and the connection port 6a is formed by the relay bus bar 5. Furthermore, although optional, in the illustrated configuration, the electrical connection structure includes an external connection terminal 4. The configuration of each of these components will be briefly described below.

[0022] The junction box 7 is provided with a junction box case (JB case) 6, which serves as a device case for housing various components including a temperature sensor 1, a relay 2, and a relay busbar 3. The JB case 6 is provided with a connection port 6a. The connection port 6a is a port that can form an electrical connection both inside and outside the JB case 6. By connecting a connector (not shown) to the connection port 6a from the outside of the JB case 6, electrical signals generated inside the JB case 6 can be transmitted to the outside of the JB case 6 via that connector.

[0023] The temperature sensor 1 includes a thermal sensing element (not shown in Figure 1) for detecting temperature, as well as an external connection part 42. The thermal sensing element is a component that detects temperature and outputs an electrical signal corresponding to the detected temperature. A thermistor can be suitably applied as the thermal sensing element. A thermistor outputs a voltage corresponding to the temperature because its internal resistance changes with temperature. Any type of thermistor can be applied, such as an NTC thermistor, PTC thermistor, or CTR thermistor. In addition to a thermistor, a temperature measurement sensor using a thermocouple may also be applied as the thermal sensing element.

[0024] The external connection part 42 is an electrode that outputs an electrical signal corresponding to the temperature detected by the thermal element to the outside of the temperature sensor 1. In other words, the electrical signal output by the thermal element located inside the temperature sensor 1 can be taken out to the outside of the temperature sensor 1 via the external connection part 42. The external connection part 42 is provided as a terminal on the temperature sensor 1. That is, the external connection part 42 is provided as a part in which a metal piece protrudes to the outside of the temperature sensor 1. In the illustrated configuration, the temperature sensor 1 has two terminals as the external connection part 42, protruding from the upper side (+x direction) of the figure toward the front side (+z direction). The temperature sensor 1 is not provided with any wires that output electrical signals. Note that the x, y, and z directions in Figure 1 are based on the directions defined for the temperature sensor unit in Figures 2 and later.

[0025] The temperature sensor 1 is not particularly limited in its specific structure as long as it has a heat-sensitive element and an external connection part 42, but it is preferable to further have a resin case 20 and a fixing terminal 10. The resin case 20 is a resin member that holds the heat-sensitive element, and the external connection part 42 is also provided protruding from the resin case 20. The fixing terminal 10 is a metal terminal and is provided in contact with at least a part of the resin case 20. Preferably, the fixing terminal 10 is joined to the resin case 20. The fixing terminal 10 has a fixing part 11 that can be fixed to a target member. A suitable configuration of the temperature sensor 1 will be illustrated in detail later.

[0026] In the electrical connection structure shown in Figure 1, a temperature sensor 1 is attached to a relay busbar 3, which is the target component, and is connected to a relay 2 in an automobile junction box 7. The temperature sensor 1 is fixed to the relay busbar 3 by a fixing part 11 with the surface of the fixing terminal 10 in contact with the relay busbar 3. Fixing is done by inserting a screw (not shown) through a screw insertion hole provided as a through hole in the fixing part 11 and fastening the screw to the relay busbar 3.

[0027] In the temperature sensor 1 attached to the relay busbar 3, two external connection parts 42 protruding from the outside of the resin case 20 are each electrically connected to a relay busbar 5. More specifically, an external connection terminal 4 is electrically connected to each external connection part 42. Then, at the external connection terminal 4, the relay busbar 5 is electrically connected to the side opposite to the external connection part 42 of the temperature sensor 1. The relay busbar 5 extends to the connection port 6a provided in the JB case 6, and the end opposite to the one connected to the external connection terminal 4 is connected to the connection port 6a. In other words, the relay busbar 5 electrically connects the external connection part 42 of the temperature sensor 1 and the connection port 6a via the external connection terminal 4.

[0028] The type of external connection terminal 4 is not particularly limited, as long as it can connect to the external connection part 42 of the temperature sensor 1 and the relay bus bar 5 on both sides. In the illustrated configuration, a tuning fork terminal is used as the external connection terminal 4. The tuning fork terminal has a branched part at its tip, and an electrical connection is formed between it and the external connection part 42 by sandwiching the external connection part 42 between the branched parts. In addition to the tuning fork terminal, FF terminals (female-female terminals) can also be suitably used as the external connection terminal 4. The relay bus bar 5 is also not particularly limited in its specific configuration as long as it is made of a bus bar, that is, as long as the entire structure is made of a continuous metal plate or rod, and its shape and path can be set according to the structure of the external connection terminal 4 and the connection port 6a, and their relative positions. Furthermore, the connection between the external connection part 42 of the temperature sensor 1 and the relay bus bar 5 does not necessarily have to be made of the external connection terminal 4; for example, the external connection part 42 and the relay bus bar 5 may be connected directly. For direct connection between the external connection part 42 and the relay busbar 5, welding or joining with a conductive material such as solder may be used as appropriate.

[0029] In this structure, where a temperature sensor 1 is attached to the relay busbar 3 as the target component, and an electrical connection is formed between the temperature sensor 1 and the connection port 6a, the temperature of the relay busbar 3 can be detected by the temperature sensor 1, and this temperature information can be transmitted to the outside of the junction box 7. When the relay 2 generates heat during operation, the relay busbar 3 is heated. This heat from the relay busbar 3 is transmitted to the internal heat-sensitive element of the temperature sensor 1 via the fixing terminal 10 and the resin case 20. The heat-sensitive element then emits an electrical signal corresponding to the detected temperature, which is output from the external connection part 42. Furthermore, this electrical signal is output to the outside of the junction box 7 from the connection port 6a via the external connection terminal 4 and the relay busbar 5. If a connector connected to a control device such as an ECU is connected to the connection port 6a, the temperature information detected by the heat-sensitive element can be input to the control device and used to control the junction box 7, such as controlling the operation of the relay 2.

[0030] In the electrical connection structure according to this embodiment, the electrical connection path from the external connection part 42 of the temperature sensor 1 to the connection port 6a is configured by an external connection terminal 4 and an intermediate bus bar 5. In other words, the path from the external connection part 42 to the connection port 6a is connected by the intermediate bus bar 5 and the optionally provided external connection terminal 4, without the use of electric wires. There is also no need to use protective tubes to protect the electrical connections between components.

[0031] In this way, by constructing the entire electrical connection path between the temperature sensor 1 and the outside of the device (outside the JB case 6) using busbars and terminals, which are rigid connecting members without insulation, instead of using wires, which are flexible connecting members with insulation, the cost required for constructing the electrical connection can be reduced. This is because the cost of materials required for wires and protective tubes can be reduced by eliminating the use of wires and protective tubes. Furthermore, using busbars reduces transportation costs compared to using wires. In terms of assembly and wiring, using busbars requires fewer steps, thus keeping costs down.

[0032] As described above, the external connection terminal 4 is not required, and even if it is provided, the type of external connection terminal 4 is not particularly limited. However, by using tuning fork terminals or FF terminals, even when the electrical connection path is constructed using only rigid connection members, the electrical connection between the external connection part 42 protruding from the temperature sensor 1 and the relay busbar 5 can be easily and stably formed. If a variety of relay busbars 5 with at least one different structure and dimensions are prepared, the temperature sensor 1 can be connected to the outside even if the junction box 7 has a variety of internal structures.

[0033] <Temperature Sensor Configuration> The temperature sensor 1 included in the electrical connection structure according to the embodiments of the present disclosure described above is equipped with a heat-sensitive element and an external connection part 42 configured as a terminal, and is not particularly limited in its specific structure as long as it can be attached to a target member. However, an example of a preferred structure will be described below. Figures 2 to 4 show an outline of the configuration of a preferred temperature sensor 1. Figure 2 is a perspective view, Figure 3 is a plan view, and Figure 4 is a side view. The temperature sensor 1 includes a fixing terminal 10, a resin case 20, a heat-sensitive element 30, and an internal busbar 40. The temperature sensor shown below has excellent temperature detection accuracy and insulation properties of the heat-sensitive element 30.

[0034] (Fixing Terminal) The fixing terminal 10 is a metal terminal and comprises a fixing part 11 and a mounting part 12. The fixing part 11 is a part for fixing the temperature sensor 1 to the target member and has a shape that allows it to be fixed to the target member. The specific shape of the fixing part 11 can be appropriately determined according to the type of target member and the method of fixing, but here the fixing part 11 is configured as a plate-shaped part having a screw insertion hole 111 provided as a through hole. The temperature sensor 1 can be fixed to the target member by bringing the fixing terminal 10 into contact with the target member on its lower surface 14, inserting a screw through the screw insertion hole 111, and fastening the screw to the target member. The mounting part 12 is provided integrally and continuously with the fixing part 11 and is formed in a planar shape. In detail, the mounting part 12 has a plane that can be attached together with a member such as a heat-sensitive element 30 by joining a resin case 20. In the illustrated form, the mounting part 12 is formed to be wider than at least a part of the fixing part 11. The fixing portion 11 and the mounting portion 12 are punched out from a common metal plate, and the whole is configured as a plate-shaped member.

[0035] Hereafter, in the fixing terminal 10, the direction in which the fixing part 11 and the mounting part 12 are aligned will be defined as the front-to-back direction (x direction). The direction in which the fixing part 11 is provided is the front (-x direction), and the direction in which the mounting part 12 is provided is the rear (+x direction). Furthermore, the thickness direction of the plate-shaped fixing terminal 10 will be defined as the up-down direction (z direction). The direction in which the resin case 20 is positioned relative to the fixing terminal 10 is upward (+z direction), and the direction in which the fixing terminal 10 is positioned is downward (-z direction). In addition, the direction perpendicular to the front-to-back direction (x direction) and the up-to-down direction (z direction) will be defined as the width direction (y direction).

[0036] In the illustrated configuration, the fixing terminal 10 has a fixing portion 11 and a mounting portion 12, as well as a pair of vertical wall portions 13. Each vertical wall portion 13 is configured as a planar part that rises upward from the upper surface of the mounting portion 12, and is provided at both ends of the mounting portion 12 in the width direction. The vertical wall portions 13 are also integrally constructed with the fixing portion 11 and the mounting portion 12, and are suitably formed, for example, as a structure in which a metal material is bent on both sides of the mounting portion 12 in the width direction. Through holes 131 are formed in the surface of each vertical wall portion 13.

[0037] (Resin Case and Heat-Sensing Element) The resin case 20 is an insulating component made of resin material and houses components such as the heat-sensing element 30. The resin case 20 is joined to the mounting portion 12 of the fixing terminal 10 by insert molding. In other words, the resin case 20 is formed by insert molding the resin material with the mounting portion 12 of the fixing terminal 10 as an insert component. The resin material constituting the resin case 20 is not particularly limited, but it is preferable that it has high heat resistance and does not melt, soften, or deteriorate due to the heat generated by the target component. Examples of resin materials that have high heat resistance and can be suitably applied to the resin case 20 include engineering plastics such as polyphenylene sulfide (PPS).

[0038] The overall external shape of the resin case 20 is not particularly limited, as long as it is joined to the mounting portion 12 of the fixing terminal 10 and exposes the fixing portion 11 to the outside. When the fixing terminal 10 is provided with a vertical wall portion 13, it is preferable that the vertical wall portion 13 is located inside the resin case 20. In other words, it is preferable that the vertical wall portion 13 is embedded in the resin material that constitutes the resin case 20. In this case, the through hole 131 of the vertical wall portion 13 is also filled with resin material. When the temperature sensor 1 has an internal busbar 40, it is preferable to provide a cut portion C at the lower end of the resin case 20, but the cut portion C will be described later along with the configuration of the internal busbar 40.

[0039] The resin case 20 is provided with a housing section 21. The housing section 21 is configured as a space having a bottom section 211 that aligns with the mounting section 12 of the fixing terminal 10. In the illustrated configuration, the bottom section 211 is configured as a surface parallel to the mounting section 12 of the fixing terminal 10. The shape, position, and size of the housing section 21 are not particularly limited, but in the illustrated configuration, the housing section 21 is provided as a rectangular parallelepiped recessed structure with an opening at the top. The housing section 21 is also formed to be large enough to accommodate the entire thermal element 30, which will be described next, and to allow for the filling of the sealing resin 50. Between the bottom section 211 of the housing section 21 and the upper surface of the mounting section 12 of the fixing terminal 10, the resin material constituting the resin case 20 is interposed, and this layer of resin material forms the bottom surface 22 of the resin case 20.

[0040] A heat-sensitive element 30 is housed in the housing section 21 of the resin case 20. The heat-sensitive element 30 outputs an electrical signal from the output section 31 corresponding to the detected temperature. As described above, various thermistors can be suitably applied as the heat-sensitive element 30. Alternatively, other types of temperature measuring sensors may be applied.

[0041] When a vertical wall portion 13 is provided on the fixing terminal 10, it is preferable that the thermal element 30 be positioned between a pair of vertical wall portions 13. For example, the housing portion 21 can be provided in the width direction between a pair of vertical wall portions 13. Then, the thermal element 30 can be fixed inside the housing portion 21 at a location corresponding to the position between the pair of vertical wall portions 13.

[0042] The thermal element 30 housed in the housing 21 is fixed to the bottom 211 of the housing 21. In the fixed state, the thermal element 30 faces the upper surface of the mounting portion 12 of the fixing terminal 10, with the bottom surface 22 of the resin case 20 in between. The method of fixing the thermal element 30 to the bottom 211 of the housing 21 is not particularly limited, but three fixing configurations are schematically illustrated in Figures 5A to 5C. Figures 5A and 5B are plan views, and Figure 5C is a cross-sectional view along the front-rear direction. In the configuration of Figure 5A, adhesive 35 is placed on the lower surface and peripheral edge of the thermal element 30, and the thermal element 30 is joined to the bottom 211 of the housing 21 via the adhesive 35. In the configurations of Figures 5B and 5C, the thermal element 30 is held by holding portions 36 and 37 formed on the bottom 211 of the housing 21 to match the shape of the thermal element 30. In the configuration shown in Figure 5B, a projection 36 surrounding the outer edge of the thermal element 30 is provided on the bottom 211 of the housing 21 as a holding part, and the thermal element 30 is housed in the space surrounded by the projection 36. The projection 36 can be formed integrally with the bottom surface 22 from the resin material that constitutes the resin case 20. In the configuration shown in Figure 5C, a recessed portion 37 is provided on the bottom 211 of the housing 21 to match the shape of the thermal element 30, and the thermal element 30 is fitted into this recessed portion 37. In the configuration shown in Figure 5A, the thermal element 30 is separated from the mounting portion 12 of the fixing terminal 10 by the bottom surface 22 of the resin case 20 and adhesive 35, while in the configurations shown in Figures 5B and 5C, the thermal element 30 is separated from the mounting portion 12 only by the bottom surface 22. Two or more types of adhesive 35, projection 36, and recessed portion 37 may be used in combination.

[0043] It is preferable that the interior of the housing portion 21 is filled with a sealing resin (potting resin) 50. Inside the housing portion 21, the heat-sensitive element 30 and an internal connection portion 41 of an internal bus bar 40 described below are arranged. Spaces other than those occupied by these members are occupied by the sealing resin 50, and members such as the heat-sensitive element 30 and the internal connection portion 41 are preferably embedded in the sealing resin 50.

[0044] (Internal Bus Bar) An electric signal output from an output portion 31 of the heat-sensitive element 30 is output to the outside of the temperature sensor 1 from an external connection portion 42 provided as a terminal. The specific configuration of the external connection portion 42, the relationship with the resin case 20, and the connection mode with the output portion 31 of the heat-sensitive element 30 are not particularly limited, but an embodiment in which the temperature sensor 1 is provided with an internal bus bar 40 is preferable. The internal bus bar 40 may be connected to the output portion 31 of the heat-sensitive element 30, and a region including an end portion of the internal bus bar 40 may be used as the external connection portion 42.

[0045] The internal bus bar 40 is a bus bar made of a metal material, that is, the entire internal bus bar 40 is formed of a continuous metal plate material or bar material. The internal bus bar 40 is held by the resin case 20 by insert molding of a resin material. That is, the resin case 20 is formed by performing insert molding using the internal bus bar 40 together with the fixing terminals 10 as insert components.

[0046] In the present embodiment, two internal bus bars 40 are provided. Each internal bus bar 40 is held by the resin case 20 in a state where a midway portion in the longitudinal direction (extending direction) is embedded in the resin case 20. A region including one end of each internal bus bar 40 serves as the internal connection portion 41, and a region including the other end serves as the external connection portion 42.

[0047] The internal connection portion 41 occupies a partial region including the front end portion of the internal bus bar 40, and protrudes into the space of the accommodating portion 21. The internal connection portion 41 is electrically connected to the output portion 31 of the heat-sensitive element 30. The connection method between the internal connection portion 41 of the internal bus bar 40 and the heat-sensitive element 30 is not particularly limited, but in the embodiments shown in FIGS. 2 to 5C, the internal connection portion 41 of the internal bus bar 40 and the output portion 31 of the heat-sensitive element 30 are connected by wire bonding. That is, the two are connected by welding the bonding wire 32 made of a single metal wire. Further, in the temperature sensor 1' according to the modified embodiment shown in FIG. 6, the internal connection portion 41 of the internal bus bar 40 and the heat-sensitive element 30 are connected using solder 33. Here, the internal connection portion 41 of the internal bus bar 40 and the output portion 31 of the heat-sensitive element 30 are directly soldered to each other without any intervening member. In the illustrated embodiment, the heat-sensitive element 30 is disposed so as to be fit between the two internal bus bars 40, and the heat-sensitive element 30 is bonded to the side surface (end surface on the inner side in the width direction) of each internal bus bar 40 via the solder 33. Alternatively, the heat-sensitive element 30 may be placed on the internal bus bars 40 in a form of bridging between the two internal bus bars 40, and the heat-sensitive element 30 may be bonded to the upper surface of each internal bus bar 40 via solder.

[0048] The external connection portion 42 occupies a partial region including the rear end portion of the internal bus bar 40, and protrudes to the outside of the resin case 20. The position where the external connection portion 42 protrudes on the resin case 20 is not particularly limited, but in the illustrated embodiment, the external connection portion 42 protrudes upward at a position corresponding to the rear end portion of the upper wall surface 23 of the resin case 20. As for the external appearance of the temperature sensor 1, the external connection portion 42 serving as a terminal is exposed at the rear end portion of the resin case 20 and protrudes upward.

[0049] Preferably, the internal busbar 40 has a bent portion 43 in the middle between the internal connection portion 41 and the external connection portion 42. The bent portion 43 is a structure in which the internal busbar 40 is bent longitudinally in the direction away from the mounting portion 12 of the fixing terminal 10, from the internal connection portion 41 toward the external connection portion 42. In other words, the bent portion 43 is located in the middle of the path from the internal connection portion 41 toward the external connection portion 42, and is bent upward away from the mounting portion 12 of the fixing terminal 10, from the downward side which is the direction in which the mounting portion 12 of the fixing terminal 10 is located. In the illustrated configuration, there are two bent portions 43 bent from downward to upward at the front and rear sides along the front-rear direction, and the internal busbar 40 extends in the front-rear direction between these two bent portions 43.

[0050] Furthermore, it is preferable that the internal busbar 40 has a narrowed portion 44 with a reduced cross-sectional area. The narrowed portion 44 is provided in the region between the internal connection portion 41 and the external connection portion 42, as a region whose cross-sectional area is smaller than at least one of the internal connection portion 41 and the external connection portion 42. Preferably, the narrowed portion 44 has a smaller cross-sectional area than both the internal connection portion 41 and the external connection portion 42. Here, the cross-sectional area of ​​the internal busbar 40 refers to the area of ​​the cross-section perpendicular to the longitudinal direction. In the illustrated embodiment, the cross-sectional area of ​​the narrowed portion 44 is reduced because the width dimension of the internal busbar 40 is smaller than that of the internal connection portion 41 and the external connection portion 42.

[0051] When an internal busbar 40 is placed in the temperature sensor 1, and the area including the end of the internal busbar 40 is designated as the external connection portion 42, it is preferable that the resin case 20 has a cut portion C in relation to the external connection portion 42 and the fixing terminal 10. The cut portion C is a stepped area of ​​the resin case 20 that is not occupied by the resin material, located in the middle of the path connecting the surface on which the fixing terminal 10 contacts the target member and the surface on which the external connection portion 42 of the internal busbar 40 protrudes, passing through the outer surface. In the illustrated form, the installation surface 24 of the resin case 20 is formed flush with the lower surface 14 of the fixing terminal 10 that contacts the target member, and the cut portion C is provided in the middle of the path connecting the installation surface 24 and the upper wall surface 23 on which the external connection portion 42 protrudes, between the installation surface 24 and the rear wall surface 25. Cut section C corresponds to the shape obtained by removing the corners that would be created if the mounting surface 24 and the rear wall surface 25 were both extended straight and joined together. It forms a stepped bend that bends from bottom to top, from front to back, and then again from bottom to top, along the path connecting the mounting surface 24 to the upper wall surface 23 through the outer surface of the resin case 20.

[0052] <Characteristics of the Temperature Sensor> In the temperature sensor 1 described above, a mounting portion 12 is provided integrally with the fixing portion 11 on the fixing terminal 10, and the resin case 20 is directly joined to the mounting portion 12. The thermal element 30 is fixed to the bottom portion 211 of the housing portion 21 provided in the resin case 20, and the thermal element 30 faces the mounting portion 12 with the bottom surface 22 of the resin case 20 in between. In other words, the thermal element 30 is fixed to the fixing terminal 10 without any air gap in between. As a result, the heat of the target material is efficiently transferred to the thermal element 30 via the fixing terminal 10. Therefore, a large difference is less likely to occur between the actual temperature of the target material and the temperature detected by the thermal element 30, and the accuracy of temperature detection by the thermal element 30 is improved.

[0053] The bottom surface 22 of the resin case 20 serves to bond the thermal element 30 to the fixing terminal 10 while maintaining insulation of the thermal element 30 from the fixing terminal 10. Therefore, the thinner the bottom surface 22 is formed while ensuring insulation of the thermal element 30, the shorter the distance from the target member to the thermal element 30 becomes, thereby improving the accuracy of temperature detection by the thermal element 30. For example, it is preferable to keep the thickness of the bottom surface 22 to 2 mm or less, and even to about 1 mm or less. Furthermore, by fixing the thermal element 30 to the bottom 211 of the housing 21 by bonding with adhesive 35 or holding with holding parts 36 and 37, as shown in Figures 5A to 5C, the thermal element 30 can be stably fixed, and the only member interposed between the thermal element 30 and the fixing terminal 10 is the bottom surface 22 of the resin case 20, or the bottom surface 22 of the resin case 20 and the adhesive 35, a high effect is obtained in improving the accuracy of temperature detection by the thermal element 30. Furthermore, the closer the position in the resin case 20 where the thermal element 30 is fixed is to the boundary between the fixing portion 11 and the mounting portion 12 of the fixing terminal 10, the higher the accuracy of temperature detection by the thermal element 30 can be. For example, the distance from the boundary between the fixing portion 11 and the mounting portion 12 to the thermal element 30 along the front-to-back direction of the fixing terminal 10 should be 6 mm or less, or even 4 mm or less.

[0054] In the temperature sensor 1, by using an internal busbar 40 held in the resin case 20 as a connecting member for extracting the electrical signal from the heat-sensitive element 30 to the outside, it becomes unnecessary to provide wires to the temperature sensor 1. In the electrical connection structure according to the embodiment of this disclosure, no wires are used for the electrical connection outside the temperature sensor 1, that is, the electrical connection between the temperature sensor 1 and the connection port 6a. However, by using the internal busbar 40, the internal electrical connection of the temperature sensor 1 can also be constructed without using wires or protective tubes (excluding the bonding wire 32). As a result, not only the external electrical connection of the temperature sensor 1 but also the temperature sensor 1 itself can have its component costs and the costs required for manufacturing and transportation processes reduced. Furthermore, by using the portion of the internal busbar 40 that is exposed outside the resin case 20 as the external connection portion 42, the man-hours and costs required to install an external connection terminal on the temperature sensor 1 can also be reduced. On the other hand, the connection between the internal connection portion 41 in front of the internal busbar 40 and the output portion 31 of the thermal element 30 can be easily formed even within the limited space of the housing portion 21 by wire bonding or soldering, as shown in Figures 2 to 5C and Figure 6.

[0055] In the temperature sensor 1, it is necessary to ensure insulation between the fixing terminal 10 and the heat-sensitive element 30 and the internal busbar 40. In particular, when a high voltage is applied to the target member to which the fixing terminal 10 is fixed, such as the relay busbar 3 located inside the junction box 7, ensuring insulation is important. One configuration to improve insulation is to provide a bent portion 43 in the internal busbar 40. By providing a bent portion 43 in the internal busbar 40 that bends upward, away from the mounting portion 12 of the fixing terminal 10, the external connection portion 42 exposed from the resin case 20 is positioned above the mounting portion 12. This increases the creepage distance D between the target member to which the fixing terminal 10 is fixed and the external connection portion 42, making creepage discharge from the target member to the internal busbar 40 less likely. For example, it is preferable to ensure a creepage distance D of 10 mm or more between the target member in contact with the lower surface 14 of the fixing terminal 10 and the external connection portion 42.

[0056] Another configuration to improve the insulation of the thermal element 30 is to provide a cut section C in the resin case 20. By providing a cut section C, as shown in Figure 4, the creepage distance D between the target member and the external connection section 42 of the internal busbar 40 is defined by the path along the stepped shape of the cut section C. Therefore, the creepage distance D is longer than when the installation surface 24 and the rear wall surface 25 of the resin case 20 are joined straight together without a cut section C. This makes creepage discharge less likely to occur between the target member and the internal busbar 40. Furthermore, filling the housing section 21 with sealing resin 50 and embedding the internal connection section 41 of the thermal element 30 and the internal busbar 40, as well as the connection points between them, in the sealing resin 50 also contributes to improving insulation.

[0057] In the temperature sensor 1 according to this embodiment, as described above, the heat-sensitive element 30 is fixed to the housing portion 21 of the resin case 20 which is directly bonded to the fixing terminal 10, thereby making it easier for the heat of the target material to be transferred to the heat-sensitive element 30 and improving the accuracy of temperature detection by the heat-sensitive element 30. However, there are other configurations that can improve the accuracy of temperature detection. In the illustrated temperature sensor 1, a pair of vertical walls 13 are provided on the fixing terminal 10, and the heat-sensitive element 30 is positioned between these vertical walls 13. In this case, the vertical walls 13 act as heat collectors for the heat-sensitive element 30, making it easier for the heat of the target material to be transferred to the heat-sensitive element 30 and improving the accuracy of temperature detection by the heat-sensitive element 30. Furthermore, by providing through holes 131 in the vertical walls 13 and filling the through holes 131 with resin material during insert molding, the fixing terminal 10 is less likely to come loose from the resin case 20.

[0058] Furthermore, as described above, providing a bent portion 43 in the internal busbar 40 suppresses surface discharge, but the bent portion 43 also plays a role in improving the accuracy of temperature detection. This is because providing the bent portion 43 increases the actual length of the internal busbar 40 and thus increases its thermal resistance, thereby suppressing heat dissipation (thermal draw) from the temperature sensor 1 to the outside via the internal busbar 40. In addition, providing a narrowed portion 44 with a smaller cross-sectional area in the internal busbar 40 also contributes to improving the accuracy of temperature detection by suppressing thermal draw due to the increase in thermal resistance.

[0059] The present invention is not limited in any way to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0060] 1,1' Temperature sensor 2 Relay 3 Relay busbar (target component) 4 External connection terminal 5 Intermediate busbar 6 JB case (device case) 6a Connection port 7 Junction box 10 Fixing terminal 11 Fixing part 111 Screw insertion hole 12 Mounting part 13 Vertical wall part 131 Through hole 14 Bottom surface of fixing terminal 20 Resin case 21 Housing part 211 Bottom of housing part 22 Bottom surface of resin case 23 Top wall surface of resin case 24 Installation surface of resin case 25 Rear wall surface of resin case 30 Thermal element 31 Output part 32 Bonding wire 33 Solder 35 Adhesive 36 Protrusion (holding part) 37 Recessed part (holding part) 40 Internal busbar 41 Internal connection part 42 External connection part 43 Bent part 44 Narrow section 50 Sealing resin C Cut section D Creepage distance x Front-to-back direction y Width direction z Up-and-down direction

Claims

1. An electrical connection structure for a temperature sensor, comprising: a temperature sensor attached to a target member housed in a device case, which has a thermal element for detecting temperature and an external connection part as a terminal for outputting an electrical signal corresponding to the temperature detected by the thermal element; a connection port provided in the device case and capable of forming an electrical connection inside and outside the device case; and a relay bus bar for electrically connecting the external connection part and the connection port, wherein the path from the external connection part to the connection port is formed by the relay bus bar without using electric wires.

2. The electrical connection structure for a temperature sensor according to claim 1, wherein the external connection portion is connected to the relay busbar via an external connection terminal or by welding or soldering.

3. The electrical connection structure for a temperature sensor according to claim 2, wherein the external connection terminal is a tuning fork terminal or an FF terminal.

4. The electrical connection structure for a temperature sensor according to claim 1, wherein the temperature sensor comprises a heat-sensitive element, a resin case housing the heat-sensitive element, and an internal busbar held in the resin case, wherein a region including one end of the internal busbar is an internal connection portion connected to an output portion of the heat-sensitive element that outputs an electrical signal corresponding to the temperature, and a region including the other end of the internal busbar protrudes to the outside of the resin case and is an external connection portion.

5. The electrical connection structure for a temperature sensor according to claim 4, wherein the temperature sensor is fixed to the target member by a fixing terminal provided in contact with at least a part of the resin case.

6. The electrical connection structure for a temperature sensor according to any one of claims 1 to 5, wherein the target member is an electrical component that is housed inside the case of an automobile junction box as the device case and generates heat during operation, or a member coupled with the electrical component.

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