JP3440691B2 - Power element overheat detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting overheating of a power element, and more particularly to a device for detecting overheating of a power element used in a vehicle air conditioner or the like. 2. Description of the Related Art Conventionally, there has been known an apparatus for detecting overheating of a power element such as a blower motor controller in order to prevent overheating of the power element.
No. 102816. As shown in FIG. 10, in this overheat detecting device for a power element, a heat sensitive element 74 is provided near a power element 72 for driving a blower motor 70, and the power element detected by the heat sensitive element 74 is detected. The high temperature detection circuit section 76 controls the power element 72 on and off based on the heat data in the vicinity of the power element 72 so that the power element 72 does not overheat to a predetermined temperature or higher. However, in this overheat detecting device for a power element, the mounting position of the thermal element 74 is limited by the shape and size of the thermal element 74. Therefore, there is a case where the thermal element 74 cannot be disposed near the power element 72. In this case, the detection of overheating is delayed, and the accuracy of detecting the temperature of the power element may be deteriorated. An object of the present invention is to provide an overheating detection device for a power element that can quickly and accurately detect overheating of the power element in consideration of the above facts. According to a first aspect of the present invention, there is provided a power element overheat detecting device according to the present invention, comprising: a conductive paste adhered to a vicinity of a power element and having a resistance value which changes with temperature; Energize the paste and, based on its resistance change,
Overheat detecting means for detecting overheating of the power element , wherein the conductive paste mounts the power element.
It is characterized in that the road base and the heat sink are bonded . Therefore, when the temperature of the power element rises,
The resistance value of the conductive paste changes. The conductive paste is energized by the overheat detecting means, and the overheat detecting means detects overheating of the power element based on a change in the resistance value of the conductive paste. In addition, a circuit board on which power elements are mounted
Can be bonded to the heat sink, and the conductive pace
The temperature rise due to overheating of the power element is most easily detected.
Position, and as a result, the power element
Heat detection can be performed quickly and with high accuracy. [0010] A first embodiment of a power element overheat detecting apparatus according to the present invention will be described with reference to FIGS. 1 to 3. As shown in FIG. 2, the power element 10 of the first embodiment is mounted on the upper surface 12A of a rectangular circuit board 12, and the circuit board 12 is made of ceramics or the like having good heat conduction efficiency and good insulation. It is composed of Circuit board 1
A heat sink 14 is in contact with the lower surface 12B of the second 2, and the heat sink 14 is made of a material having good conductivity such as aluminum. The conductive paste 16 is adhered to the upper surface 12A of the circuit board 12. The temperature characteristic of the resistance value of the conductive paste 16 is such that the resistance value R is proportional to the rise of the temperature T as shown in FIG. The conductive paste 16 is used for the power element 1.
0, and the conductive paste 1
Terminals 18 and 20 are adhered to the upper portions of both ends 16A and 16B, respectively. As shown in FIG. 1, terminals 18, 2
Numeral 0 is connected to a constant current power supply circuit 28 and an overheat detection circuit 30 which constitute overheat detection means by conducting wires 24 and 26, respectively. The constant current power supply circuit 28 supplies a constant current to the conductive paste 16. The overheat detecting circuit 30 detects the voltage between the terminals 18 and 20, that is, both ends 16 A, 1
6B, and compares this voltage V with a reference voltage V1 corresponding to a preset maximum allowable temperature T1 to determine whether or not the power element 10 is in an overheated state.
A predetermined output signal P is output. Next, the operation of the first embodiment will be described.
In the overheat detecting device for a power element according to the first embodiment, the resistance value R of the conductive paste 16 changes as shown in FIG.
For this reason, the constant current power supply circuit 28 supplies a constant current to the conductive paste 16, and the overheat detection circuit 30
Voltage V between both ends 16A and 16B of conductive paste 16
When the voltage V exceeds a reference voltage V1 corresponding to a preset maximum allowable temperature T1, it is determined that the power element 10 is overheated, and a predetermined output signal P
Is output. As described above, in the overheat detecting device for a power element according to the first embodiment, since the heat near the power element 10 is detected by the conductive paste 16 instead of the conventional heat-sensitive element, the conductive paste 16 is used. Can be provided at a position where the temperature rise due to overheating of the power element 10 is easily detected without violating other design requirements and with extremely high degree of freedom. Therefore, the overheating of the power element 10 can be detected quickly and with high accuracy. Next, a second embodiment of the overheat detecting device for a power element according to the present invention will be described with reference to FIGS. The same members as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted. As shown in FIG. 5, the conductive paste 36 of the second embodiment is applied to the opposing edge 12 of the circuit board 12.
C and 12D are linearly bonded to each other, and terminals 38 and 40 are bonded to the upper portions of the respective conductive pastes 36, respectively. These terminals 38 and 40 are inserted into a resin housing 22 provided on an upper part of the conductive paste 36, and the resin housing 22 is formed of a highly insulating resin. As shown in FIG.
Numeral 0 is connected by lead wires 24 and 26 to a resistance value change detecting unit 42 as an overheat detecting means that combines a constant current power supply circuit and an overheat detection circuit. The resistance change detecting section 42 supplies a constant current to the conductive paste 36.
To supply. The resistance value change detection unit 42 includes a terminal 38, a conductive paste 36, a heat sink 14,
The voltage V between the conductive paste 36 and the terminal 40 is monitored, and this voltage V is compared with a reference voltage V2 corresponding to a preset maximum allowable temperature T1 to determine whether the power element 10 is in an overheated state. Is determined, and a predetermined output signal P is output. Next, the operation of the second embodiment will be described.
In the power element overheat detection device according to the second embodiment, the resistance value R of the conductive paste 36 changes as shown in FIG.
For this reason, the resistance change detection unit 42 supplies a constant current to the conductive paste 36, and the terminal 38, the conductive paste 36, the heat sink 14, the conductive paste 36,
The voltage V between the terminals 40 is monitored, and this voltage V is set to a reference voltage V2 corresponding to a preset maximum allowable temperature T1.
Is exceeded, it is determined that the power element 10 is overheated, and a predetermined output signal P is output. As described above, in the device for detecting overheating of the power element according to the second embodiment, the heat in the vicinity of the power element 10 is detected by the conductive paste 36 instead of the conventional heat-sensitive element. Can be provided at a position where it is easy to detect a temperature rise due to overheating of the power element 10 with extremely high degree of freedom without conflicting with other design requirements. Therefore, the overheating of the power element 10 can be detected quickly and with high accuracy. Further, in the overheat detecting device for a power element according to the second embodiment, the conductive paste 36 functions as an adhesive between the resin housing 22 and the heat sink 14 by curing the conductive paste 36. Next, a third embodiment of the overheat detecting device for a power element according to the present invention will be described with reference to FIGS. The same members as those in the second embodiment are denoted by the same reference numerals, and description thereof will be omitted. As shown in FIGS. 6 and 7, the conductive paste 46 of the third embodiment is adhered in a sheet shape between the circuit board 12 on which the power element 10 is mounted and the heat sink 14. . Both ends 46 of conductive paste 46
A, 46B are opposite edges 12C, 1 of the circuit board 12;
The terminals project from the 2D to the outside, and terminals 48 and 50 are adhered to the upper portions of both ends 46A and 46B, respectively. These terminals 48 and 50 are inserted into the resin housing 22 provided on the conductive paste 46 at the top. Next, the operation of the third embodiment will be described.
In the power element overheat detection device of the third embodiment, the resistance value R of the conductive paste 46 changes as shown in FIG.
For this reason, the resistance change detecting section 42 supplies a constant current to the conductive paste 46, and the voltage between the terminals 48 and 50, that is, the voltage between both ends 46A and 46B of the conductive paste 46. V, and this voltage V
A reference voltage V corresponding to a preset maximum allowable temperature T1
If it exceeds 3, it is determined that the power element 10 is overheated, and a predetermined output signal P is output. As described above, in the overheat detection device for a power element of the third embodiment, the heat of the circuit board 12 on which the power element 10 is mounted is detected by the conductive paste 46 instead of the conventional heat-sensitive element. The conductive pace 46 is located at a position where the temperature rise due to overheating of the power element 10 is most easily detected,
It can be provided with a very high degree of freedom without conflicting with other design requirements. Therefore, the overheating of the power element 10 can be detected quickly and with high accuracy. In the overheat detecting device for a power element according to the third embodiment, the conductive paste 46 is hardened so that the conductive paste 46 becomes an adhesive between the circuit board 12 and the heat sink 14 and the resin housing 22 and the heat sink. 14 also functions as an adhesive. In the above, the present invention has been described in detail with respect to a specific embodiment. However, the present invention is not limited to such an embodiment, and various other embodiments are included within the scope of the present invention. It is clear to a person skilled in the art that is possible. For example, as shown in FIGS. 8 and 9, the present invention can be applied to a plurality of power elements 10 mounted on the same heat sink 14, and the overheating of each power element 10 can be individually and quickly performed with a simple configuration. And it can detect with high precision. In this embodiment, the upper surface 14A of the heat sink 14 needs to be subjected to a surface treatment such as painting in order to electrically insulate the conductive paste 56. According to a first aspect of the present invention, there is provided an overheat detecting device for a power element, comprising: a conductive paste which is adhered to the vicinity of the power element and whose resistance value changes with temperature; based on the resistance value changes, and the overheat detection means for detecting overheating of the power device, comprising a conductive paste
Adhesion of circuit board for mounting power element and heat sink
Since it has to have an excellent effect that the overheat detection of the power device can be performed quickly and accurately. [0032]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic plan view showing a power element overheat detection device according to a first embodiment of the present invention. FIG. 2 is a schematic perspective view showing a device for detecting overheating of a power element according to the first embodiment of the present invention. FIG. 3 is a graph showing a temperature characteristic of a resistance value of a conductive paste. FIG. 4 is a schematic cross-sectional view illustrating a device for detecting overheating of a power element according to a second embodiment of the present invention. FIG. 5 is a schematic perspective view showing a power device overheat detection device according to a second embodiment of the present invention. FIG. 6 is a schematic sectional view showing a power element overheat detection device according to a third embodiment of the present invention. FIG. 7 is a schematic perspective view showing a power element overheat detection device according to a third embodiment of the present invention. FIG. 8 is a schematic cross-sectional view showing a device for detecting overheating of a power element according to another embodiment of the present invention. FIG. 9 is a schematic perspective view showing a device for detecting overheating of a power element according to another embodiment of the present invention. FIG. 10 is a schematic configuration diagram illustrating a power element overheat detection device according to a conventional embodiment. [Description of Signs] 10 Power element 12 Circuit board 14 Heat sink 16 Conductive paste 28 Constant current power supply circuit (Overheat detecting means) 30 Overheat detecting circuit (Overheat detecting means) 36 Conductive paste 42 Resistance change detecting section (Overheat detecting means) ) 46 conductive paste 56 conductive paste

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-239377 (JP, A) JP-A-8-29267 (JP, A) JP-A-54-14681 (JP, A) JP-A-60-1985 102816 (JP, A) Japanese Utility Model Showa 57-197798 (JP, U) Japanese Patent Publication No. 43-9787 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60H 1/00-3 / 06 G05F 1/00-1/10

Claims (1)

(57) [Claim 1] A conductive paste adhered in the vicinity of a power element and having a resistance value that changes with temperature, and a current is applied to the conductive paste, and based on the resistance value change, Overheating detection means for detecting overheating of the power element , wherein the conductive paste mounts the power element.
Overheat detection device for a power element, wherein a circuit board and a heat sink are bonded to each other .