Temperature sensor

Abstract

Provided is a temperature sensor having higher thermal responsiveness and capable of performing high-precision temperature measurement. A temperature sensor according to the present invention is provided with: a heat-sensitive element (2) having electrode surfaces on the upper surface and the lower surface; a pair of lead terminals (3) electrically connected to the heat-sensitive element; a resin sealing part (4) for sealing the heat-sensitive element and the front end parts of the pair of lead terminals with a resin; and a conductive floating terminal (5) embedded in the resin sealing part in a manner that at least one surface is exposed and separated from the pair of lead terminals, and the heat-sensitive element is mounted on the floating terminal in a state that the electrode surface of the lower surface and the floating terminal are bonded by a conductive bonding material. The electric connection between the floating terminal and one of the pair of lead terminals and the electric connection between the electrode surface of the upper surface and the other of the pair of lead terminals are performed by bonding wires.

Description

Technical Field

[0001] The present invention relates to a temperature sensor for measuring the temperature of a coil wire or the like of a motor stator. Background Art

[0002] For example, since a motor stator or the like becomes high in temperature, it is necessary to perform control by means of a temperature sensor. Therefore, a temperature sensor is mounted on a measurement object such as a coil wire of a motor stator.

[0003] As a temperature sensor provided in a state of being in contact with such a measurement object, a temperature sensor in which a sheet-type thermistor is mounted on an insulating substrate is known.

[0004] Conventionally, for example, Patent Document 1 discloses a thin-type temperature sensor having, in a temperature sensing portion: an insulating substrate having a sheet-type thermistor mounting recess and a through hole; a lower surface electrode portion formed in a lower region of the sheet-type thermistor mounting recess; an upper surface electrode portion formed in an upper region of the through hole; an upper surface electrode heat collecting portion formed in a lower region of the through hole; a sheet-type thermistor buried in the sheet-type thermistor mounting recess and having a lower electrode electrically connected to the lower surface electrode portion; and a conductive portion electrically connecting the upper surface electrode heat collecting portion to the upper surface electrode portion and the upper surface electrode portion to an upper electrode of the sheet-type thermistor.

[0005] Also, a temperature sensor having a heat collecting film such as a metal film provided on a contact surface with a measurement object is known. For example, Patent Document 2 discloses a temperature sensor including: an insulating film; a thin film thermistor portion formed by patterning a thermistor material on a surface of the insulating film; a pair of comb-shaped electrodes patterned on at least one of an upper side and a lower side of the thin film thermistor portion in such a manner as to have a plurality of comb portions and to face each other; a pair of patterned electrodes connected to the pair of comb-shaped electrodes and patterned on the surface of the insulating film; and a heat collecting film patterned on a back surface of the insulating film and directly below the thin film thermistor portion with a material having a higher thermal conductivity than that of the insulating film.

[0006] Furthermore, Patent Document 3 also discloses a temperature sensor including a thermosensitive element in which a thermosensitive film and an electrode are formed on one surface of an insulating substrate and a heat collecting film such as a metal is formed on the other surface of the insulating substrate.

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2006-64497

[0008] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2016-138773

[0009] Patent Document 3: Japanese Utility Model Publication No. 4-3325

[0010] The prior art described above has the following problems.

[0011] That is, in a temperature sensor for detecting the temperature of a measurement object such as a coil wire of a motor stator that becomes high temperature, in order to quickly respond to the heat of the motor for control, higher thermal responsiveness and thermal followability are required. However, in the prior art, although the heat is efficiently transferred by forming a heat collecting film such as metal on the surface in contact with the measurement object to improve the thermal responsiveness, it is difficult to obtain higher thermal responsiveness and thermal followability because an insulating substrate or the like is interposed between the heat collecting film and the thermosensitive element. Summary of the Invention

[0012] The present invention has been completed in view of the above problems, and an object thereof is to provide a temperature sensor having higher thermal responsiveness so as to enable highly accurate temperature measurement.

[0013] In order to solve the above problems, the present invention adopts the following structure. That is, the temperature sensor according to the first invention is characterized by comprising: a thermosensitive element having electrode surfaces on the upper surface and the lower surface; a pair of lead terminals electrically connected to the thermosensitive element; a resin sealing portion for sealing the thermosensitive element and the front end portions of the pair of lead terminals with resin; and a conductive floating terminal buried in the resin sealing portion so that at least one surface is exposed and spaced apart from the pair of lead terminals, the thermosensitive element being mounted on the floating terminal in a state where the electrode surface on the lower surface is bonded to the floating terminal with a conductive bonding material, and the electrical connection between the floating terminal and one of the pair of lead terminals and the electrical connection between the electrode surface on the upper surface and the other of the pair of lead terminals being performed by bonding wires.

[0014] In this temperature sensor, since the thermosensitive element is mounted on the floating terminal in a state where the electrode surface on the lower surface is bonded to the floating terminal with a conductive bonding material, the thermosensitive element is in direct contact with the floating terminal that functions as a heat sink, and thus higher thermal responsiveness can be obtained.

[0015] Moreover, since the electrical connection between the floating terminal and one of the pair of lead terminals and the electrical connection between the electrode surface on the upper surface and the other of the pair of lead terminals are performed by bonding wires, the floating terminal is in a state of being thermally insulated (thermally floating) from the pair of lead terminals, and the heat received by the floating terminal from the measurement object is difficult to dissipate from the lead terminals.

[0016] Therefore, in this temperature sensor, by arranging it in a state where the exposed surface of the floating terminal that functions as a heat sink and is thermally insulated is in contact with the measurement object, heat can be efficiently transferred to the thermosensitive element mounted on the floating terminal, and thus higher thermal responsiveness can be achieved to measure the temperature.

[0017] The temperature sensor according to the second invention is characterized in that, in the first invention, the floating terminal is exposed on the lower surface and the side surface of the resin sealing portion.

[0018] That is, in this temperature sensor, since the floating terminal is exposed on the lower surface and the side surface of the resin sealing portion, when it is set to be buried in the measurement object, it can receive the heat of the measurement object not only from the lower surface but also from the side surface, and transfer this heat to the thermosensitive element, thereby further improving the thermal responsiveness.

[0019] The temperature sensor according to the third invention is characterized in that, in the first invention or the second invention, the floating terminal is arranged at a distance from the front ends of the pair of lead terminals, and is in the shape of a long plate or a prism extending in a direction orthogonal to the extending direction of the pair of lead terminals.

[0020] That is, in this temperature sensor, since the floating terminal is arranged at a distance from the front ends of the pair of lead terminals and is in the shape of a long plate or a prism extending in a direction orthogonal to the extending direction of the pair of lead terminals, the exposed area of the lower surface increases in the extending direction, which is suitable for the case of being arranged on a measurement object extending along the extending direction of the floating terminal, etc. And the floating terminal as a whole can be further separated from the lead terminals, thereby further improving the thermal responsiveness.

[0021] The temperature sensor according to the fourth invention is characterized in that, in the first or second invention, the resin sealing portion has a connector portion, and by inserting a pair of external wirings into the connector portion, the base ends of the pair of lead terminals can be connected to the pair of external wirings.

[0022] That is, in this temperature sensor, since the resin sealing portion has a connector portion, and by inserting a pair of external wirings into the connector portion, the base ends of the pair of lead terminals can be connected to the pair of external wirings, the external wirings can be easily connected through the connector portion.

[0023] The temperature sensor according to the fifth invention is characterized in that, in the first invention, the pair of lead terminals extend parallel to each other within the resin sealing portion, and the floating terminal extends between the pair of lead terminals.

[0024] That is, in this temperature sensor, since the floating terminal extends between the pair of lead terminals, the exposed area of the lower surface increases in the extending direction, which is suitable for the case of being arranged on a measurement object extending along the extending direction of the lead terminals (the extending direction of the floating terminal), etc.

[0025] According to the present invention, the following effects are achieved.

[0026] That is, in the temperature sensor according to the present invention, since the thermosensitive element is mounted on the floating terminal in a state where the electrode surface on the lower surface is bonded to the floating terminal with a conductive bonding material, and the electrical connection between the floating terminal and one of the pair of lead terminals and the electrical connection between the electrode surface on the upper surface and the other of the pair of lead terminals are made through bonding wires, heat can be efficiently transferred to the thermosensitive element mounted on the floating terminal that functions as a heat sink and is thermally insulated. Thus, it is possible to have a high thermal responsiveness to measure temperature.

[0027] Thus, in the temperature sensor of the present invention, the thermal responsiveness is improved, so it is suitable for highly accurate temperature measurement of coil wires of a motor stator and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 FIG. 9 is a perspective view from above of the temperature sensor shown by looking into the interior in the first embodiment of the temperature sensor according to the present invention.

[0029] Figure 2 FIG. 13 is a perspective view from below of the temperature sensor shown in the first embodiment.

[0030] Figure 3 FIG. 17 is an enlarged perspective view of the main part of the thermosensitive element mounted on the floating terminal shown in the first embodiment.

[0031] Figure 4 FIG. 21 is a cross-sectional view along the floating terminal showing the state where the temperature sensor is buried in the object to be measured in the first embodiment.

[0032] Figure 5 FIG. 25 is a perspective view of the temperature sensor viewed from the base end side in the second embodiment of the temperature sensor according to the present invention.

[0033] Figure 6 FIG. 29 is a perspective view from above of the temperature sensor shown by looking into the interior in the third embodiment of the temperature sensor according to the present invention.

[0034] Figure 7 FIG. 33 is a perspective view from above of the temperature sensor shown by looking into the interior in the fourth embodiment of the temperature sensor according to the present invention.

[0035] Figure 8 FIG. 37 is a perspective view from above of the temperature sensor shown by looking into the interior in the fifth embodiment of the temperature sensor according to the present invention.

[0036] Figure 9 FIG. 41 is a graph showing a thermal time constant simulation of the temperature change with respect to time in an example of the temperature sensor according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0037] Hereinafter, with reference to Figures 1 to 4 a first embodiment of the temperature sensor according to the present invention will be described. In addition, in a part of the drawings used in the following description, the scale is appropriately changed as needed so that each part can be made recognizable or easily recognizable in size.

[0038] As Figures 1 to 4 shown, the temperature sensor 1 of the present embodiment includes: a thermosensitive element 2 having electrode surfaces 2a on the upper and lower surfaces; a pair of lead terminals 3 electrically connected to the thermosensitive element 2; a resin sealing portion 4 that resin-seals the thermosensitive element 2 and the front end portions of the pair of lead terminals 3; and a conductive floating terminal 5 that is buried in the resin sealing portion 4 so that at least one surface is exposed and is spaced apart from the pair of lead terminals 3.

[0039] In addition, the temperature sensor 1 of the present embodiment is provided, for example, in a state where at least the exposed lower surface of the floating terminal 5 is in contact with the coil wire of the motor stator to detect the temperature of the coil wire.

[0040] Furthermore, the thermosensitive element 2 is mounted on the floating terminal 5 in a state where the electrode surface 2a on the lower surface is bonded to the floating terminal 5 with a conductive bonding material 6.

[0041] The above-mentioned conductive bonding material 6 is, for example, solder.

[0042] Furthermore, the electrical connection between the floating terminal 5 and one of the pair of lead terminals 3 and the electrical connection between the electrode surface 2a on the upper surface and the other of the pair of lead terminals 3 are performed by bonding wires Y.

[0043] The above-mentioned floating terminal 5 is exposed on the lower surface and the side surface of the resin sealing portion 4.

[0044] Moreover, the floating terminal 5 is arranged at a distance from the front ends of the pair of lead terminals 3 and is in the shape of a long plate or a prism extending in a direction orthogonal to the extending direction of the pair of lead terminals 3.

[0045] The above-mentioned thermosensitive element 2 is a sheet-type thermistor in which conductive material layers such as metals are formed on the upper and lower surfaces of a plate-shaped thermistor material portion 2b as electrode surfaces 2a.

[0046] The above-mentioned pair of lead terminals 3 are lead frames extending parallel to each other within the resin sealing portion 4.

[0047] The above-mentioned resin sealing portion 4 is formed of an insulating resin such as epoxy resin, and is molded into a rectangular plate shape or a low box shape in plan view.

[0048] In addition, the resin sealing portion 4 is sealed in such a manner as to cover the floating terminal 5, the thermosensitive element 2, the bonding wire Y, and the front end portion side of the pair of lead terminals 3.

[0049] Two of the above-mentioned bonding wires Y are respectively laid between one of the floating terminal 5 and the pair of lead terminals 3 and between the electrode surface 2a on the upper surface and the other of the pair of lead terminals 3.

[0050] The above-mentioned floating terminal 5 is formed of a highly thermally conductive conductive material such as copper, for example.

[0051] The floating terminal 5 is formed in a rod shape (long plate shape or prism shape) with a rectangular cross section, and not only the lower surface but also both end surfaces are exposed to the resin sealing portion 4.

[0052] Moreover, the lower surface of the floating terminal 5 is set to be flush with the lower surface of the resin sealing portion 4. Additionally, a TIM (Thermal Interface Material) material or a heat sink can be attached to the lower surface of the floating terminal 5 and the lower surface of the resin sealing portion 4, which are the contact surfaces with the object to be measured, to absorb unevenness.

[0053] Thus, in the temperature sensor 1 of the present embodiment, since the thermosensitive element 2 is mounted on the floating terminal 5 in a state where the electrode surface 2a on the lower surface is bonded to the floating terminal 5 with the conductive bonding material 6, the thermosensitive element 2 is in direct contact with the floating terminal 5 that functions as a heat sink, thereby enabling a high thermal responsiveness to be obtained.

[0054] Moreover, since the electrical connection between the floating terminal 5 and one of the pair of lead terminals 3 and the electrical connection between the electrode surface 2a on the upper surface and the other of the pair of lead terminals 3 are performed through the bonding wire Y, the floating terminal 5 is in a state of being thermally insulated from the pair of lead terminals 3, and the heat received by the floating terminal 5 from the object to be measured is difficult to dissipate from the lead terminals 3.

[0055] Therefore, in this temperature sensor 1, by setting it in a state where the exposed surface of the floating terminal 5 that functions as a heat sink and is thermally insulated is in contact with the object to be measured, heat can be efficiently transferred to the thermosensitive element 2 mounted on the floating terminal 5, thereby enabling a high thermal responsiveness to measure the temperature.

[0056] Moreover, since the floating terminal 5 is exposed on the lower surface and the side surface of the resin sealing portion 4, as Figure 4 shown, when it is set to be buried in the object to be measured S, not only can heat from the object to be measured S be received from the lower surface, but also heat from the object to be measured S can be received from the side surface and transferred to the thermosensitive element 2, thereby enabling the thermal responsiveness to be further improved.

[0057] Furthermore, since the floating terminal 5 is arranged at a distance from the front ends of the pair of lead terminals 3 and is in the shape of a long plate or prism extending in a direction orthogonal to the extending direction of the pair of lead terminals 3, the exposed area of the lower surface increases in the extending direction, which is suitable for being arranged on a measurement object extending in the extending direction of the floating terminal 5, etc. Also, the entire floating terminal 5 can be further spaced apart from the lead terminals, thereby further improving the thermal responsiveness.

[0058] Next, hereinafter, refer to Figures 5 to 8 The second to fifth embodiments of the temperature sensor according to the present invention will be described. In addition, in the description of each of the following embodiments, the same structural elements described in the above embodiments are denoted by the same reference numerals, and their descriptions are omitted.

[0059] The difference between the second embodiment and the first embodiment is that, in the first embodiment, the resin sealing portion 4 is only plate-shaped, and the base ends of the pair of lead terminals 3 protrude from the base end surface. In contrast, in the temperature sensor 21 of the second embodiment, as Figure 5 shown, the resin sealing portion 24 has a connector portion 24a, and by inserting a pair of external wirings into the connector portion 24a, the base ends of the pair of lead terminals 3 can be connected to the pair of external wirings.

[0060] That is, the resin sealing portion 24 of the second embodiment includes: a front-end side sealing portion 24b that seals the front-end sides of the thermosensitive element 2, the floating terminal 5, and the pair of lead terminals 3; and the above-mentioned connector portion 24a that is connected to the base end of the front-end side sealing portion 24b.

[0061] The above-mentioned connector portion 24a opens in a rectangular shape toward the base end side and can be inserted with the terminals of a pair of external wirings. The base ends of the pair of lead terminals 3 protrude into the interior of the connector portion 24a.

[0062] In this way, in the temperature sensor 21 of the second embodiment, since the resin sealing portion 24 has the connector portion 24a, and by inserting a pair of external wirings into the connector portion 24a, the base ends of the pair of lead terminals 3 can be connected to the pair of external wirings, the external wirings can be easily connected through the connector portion 24a.

[0063] Next, the difference between the third embodiment and the first embodiment is that, in the first embodiment, the floating terminal 5 is arranged at a distance from the front ends of the pair of lead terminals 3 and is in the shape of a long plate or prism extending in a direction orthogonal to the extending direction of the pair of lead terminals 3. In contrast, in the temperature sensor 31 of the third embodiment, as Figure 6 shown, the floating terminal 35 extends between the pair of lead terminals 3.

[0064] That is, the floating terminal 35 of the third embodiment is in the shape of a long plate or a prism, and extends parallel to the lead terminals 3 between the pair of lead terminals 3 within the resin sealing portion 4.

[0065] Moreover, the pair of lead terminals 3 extend to the vicinity of the front end of the resin sealing portion 4.

[0066] Thus, in the temperature sensor 31 of the third embodiment, since the floating terminal 35 extends between the pair of lead terminals 3, the exposed area of the lower surface increases in the extending direction, which is suitable for the case of being disposed on a measurement object extending along the extending direction of the lead terminals 3 (the extending direction of the floating terminal 35), etc.

[0067] Next, the difference between the fourth embodiment and the third embodiment is that in the third embodiment, the floating terminal 35 is in the shape of a long plate or a prism extending between the pair of lead terminals 3. In contrast, in the temperature sensor 41 of the fourth embodiment, as Figure 7 shown, the floating terminal 45 is in a substantially T shape having a longitudinally long portion 45a and a laterally long portion 45b. The longitudinally long portion 45a extends between the pair of lead terminals 3, and the laterally long portion 45b is connected to the front end of the longitudinally long portion 45a and is long in a direction orthogonal to the extending direction of the lead terminals 3 and is rectangular in plan view.

[0068] The above-mentioned laterally long portion 45b is formed to have a width wider than the width of the floating terminal 5 of the first embodiment.

[0069] Thus, in the temperature sensor 41 of the fourth embodiment, since the floating terminal 45 is in a substantially T shape having a longitudinally long portion 45a and a laterally long portion 45b, the exposed area of the lower surface is further increased, thereby enabling higher thermal responsiveness to be obtained.

[0070] Next, the difference between the fifth embodiment and the first embodiment is that in the first embodiment, the floating terminal 5 is in the shape of a long plate or a prism extending in a direction orthogonal to the extending direction of the lead terminals 3. In contrast, in the temperature sensor 51 of the fifth embodiment, as Figure 7 shown, the floating terminal 55 is in the shape of a rectangular plate that is long in the extending direction of the lead terminals 3 in plan view.

[0071] That is, in the fifth embodiment, the pair of lead terminals 53 are shorter than those in the first embodiment. Correspondingly, the floating terminal 55 is in the shape of a flat plate that expands in the extending direction of the lead terminals 3.

[0072] Thus, in the temperature sensor 51 of the fifth embodiment, since the floating terminal 55 is in the shape of a flat plate that expands in the extending direction of the lead terminals 3, the exposed area of the lower surface and the side surface increases, thereby enabling better thermal responsiveness to be obtained.

[0073] Example

[0074] The temperature sensor of the first embodiment was set on the winding in a state where the lower surface of the heat-receiving surface, i.e., the floating terminal, and the lower surface of the resin sealing portion were in contact with the winding via a heat sink. Under this setting, a thermal time constant simulation was performed when the winding was instantaneously heated to 150°C. The simulation results are shown in Figure 9 .

[0075] In addition, the ambient temperature was 25°C, and the simulation was performed with the thermal conductivity of the heat sink set to 2 W / mK.

[0076] Moreover, the thermal time constant is the time until the temperature of the thermosensitive element reaches 104°C when the temperature of the winding is 150°C.

[0077] From this result, it can be seen that in the temperature sensor of the present invention, the thermal time constant is 0.7 seconds, so the thermal responsiveness is high and the temperature of the winding can be measured quickly.

[0078] In addition, the technical scope of the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the gist of the present invention.

[0079] For example, in the above-described embodiments, a thermistor was used. However, as the thermistor, a chip thermistor, a thin-film thermistor, or a film thermistor can be used, and a pyroelectric element or the like can also be used. In particular, a thermosensitive element having a heat resistance of 200°C is preferably used.

[0080] Explanation of Reference Numerals

[0081] 1, 21, 31, 41, 51 Temperature sensor

[0082] 2 Thermosensitive element

[0083] 2a Electrode surface

[0084] 3 Lead terminal

[0085] 4, 24 Resin sealing portion

[0086] 5, 35, 45, 55 Floating terminal

[0087] 6 Conductive bonding material

[0088] 24a Connector portion

[0089] Y Bonding wire

Claims

1. A temperature sensor, characterized in that, Comprising: a thermosensitive element having electrode surfaces on an upper surface and a lower surface; a pair of lead terminals electrically connected to the thermosensitive element; a resin sealing portion for sealing the thermosensitive element and front end portions of the pair of lead terminals with resin; and a conductive floating terminal embedded in the resin sealing portion in such a manner that at least one surface is exposed and spaced apart from the pair of lead terminals, wherein the thermosensitive element is mounted on the floating terminal in a state where the electrode surface on the lower surface is bonded to the floating terminal with a conductive bonding material, and electrical connection between the floating terminal and one of the pair of lead terminals and electrical connection between the electrode surface on the upper surface and the other of the pair of lead terminals are performed by bonding wires.

2. The temperature sensor according to claim 1, wherein the floating terminal is exposed on a lower surface and a side surface of the resin sealing portion.

3. The temperature sensor according to claim 1 or 2, wherein the floating terminal is arranged spaced apart from front ends of the pair of lead terminals and is in a long plate shape or a prism shape extending in a direction orthogonal to an extending direction of the pair of lead terminals.

4. The temperature sensor according to claim 1 or 2, wherein the resin sealing portion has a connector portion, and by inserting a pair of external wirings into the connector portion, the base ends of the pair of lead terminals can be connected to the pair of external wirings.

5. The temperature sensor according to claim 1, wherein the pair of lead terminals extend parallel to each other within the resin sealing portion, and the floating terminal extends between the pair of lead terminals.

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