TEMPERATURE DETECTION DEVICE

Abstract: In a temperature detection device, a drawn terminal cap (15) is disposed at an open end part of a metal casing (9), which contains a temperature detection element (10) on the inside bottom face thereof. In the cone shaped hollow inner space inside a cone shaped skirt part (152) of the terminal cap (15), the top end of a pressure spring (12) is held to press a temperature detection element (10) against the bottom face of the casing (9). The terminal cap (15) is fixed with an insulation ring cap (16) disposed on the skirt part (152) thereof, by calking by the upper calking edge part (903) of the casing (9), with the insulation and sealing rubber ring (14) disposed thereunder.

Description: Temperature detection device FIG. 1 is a partially sectional front view of a conventional temperature detection device for detecting a temperature of cooling water of an automobile engine. In FIG. 1, the temperature detection device comprises a metal casing 1 having an opening at an upper end thereof. A temperature detection element 2, for example, a temperature-dependent resistor, such as a thermistor, having electrodes 2', 2' on the upper and the lower face thereof, is disposed on an inner face of a casing bottom 1' in the casing 1 at space of a smaller inner diameter. A pressure spring 4 presses the temperature detection element 2 to the inner face of the casing bottom 1' through a terminal disk 3, which is disposed between the pressure spring 4 and the temperature detection element 2. An insulation liner 5 inserted in the metal casing 1 closely adhered to the inner face of the casing 1 for. insulating inner elements, namely, the temperature detection element 2, the terminal disk 3 and the pressure spring 4 from the metal casing 1. A rubber packing 6 for attaining moisture-proof and gasproof ability is disposed on the upper face of a shoulder shaped part at a connecting portion between a smaller inner diameter space in the casing 1 and larger inner diameter space in the casing 1. A terminal 7 for taking a detected signal is disposed at the upper open space of the casing 1 so as to make contact to the upper end part of the pressure spring 4. An insulation block 8 for holding the terminal 7 is disposed at the inner face of the casing 1 and the outer face of the terminal 7 inbetween and fixed by calking of an upper edge 1" of the casing 1 to the upper end of slots 8' on the outer side of the insulation block 8. Then the temperature detection element 2, the terminal disk 3, the pressure spring 4, the insulation liner 5, the gum packing 6 and the terminal 7 are assembled in the casing 1 in a predetermined manner such that the insulation block 8 between the upper part of the casing 1 and the terminal 7 is fixed by calking of the upper edge 1" of the casing 1 resisting a pressure of the pressure spring 4. In the above-mentioned conventional temperature detecting device, a temperature is detected by, for instance, immersing the outer bottom of the metal casing in a hot water, thereby conducting the temperature through the bottom 1' to the thermistor 2. But the problem has been that the terminal 7 is made from a solid brass rod by machine cutting. And in ordinary cases, the terminal 7 is molded in the insulation block 8, by means of insert molding. Therefore, because of such machine cutting from a brass rod and subsequent insert molding the manufacturing cost has been expensive. In the above-mentioned temperature detecting device, it has also been necessary that an anti-rotation-slippage torque between the insulation block 8 and the upper part of the metal casing 1 is kept above a predetermined threshold. For that purpose, in the conventional case, slots 8', 8' are formed at surrounding face of the insulation block 8 as shown in FIG. 2, and the upper edge 1" of the metal casing 1 is calked at respective portions corresponding to the slot 8'. Accordingly, for calking the upper edge 1" of the metal casing 1 to the corresponding slot 8" of the insulation block 8, a positioning operation to the insulation block finding a right positioning angle is indispensable, and such positioning in the right angle can not be made by a robot. insertion machine. Hence a temperature detection device of the conventional type is unsuitable for mass production. Summary of the Invention The present invention purposes to provide a temperature detection device comprising an enclosure of a high thermal conductive substance having a slender cup shaped part defining a slender first space of a smaller inner diameter and a shallow and wider part defining a shallow and wider second space of a larger inner diameter and connected said first space, the upper edge of the wider part being formed in cone shaped calking edge, a temperature detection element disposed on an inner bottom face of slender cup shaped part of the enclosure, a drawn terminal cap having a slender top part of smaller diameter for serving as connection terminal and a cone shaped skirt part connected to the slender top part, the drawn terminal cap having continuous hollow space inside the slender top part and the skirt part, a packing ring disposed between a ring shaped face of the bottom of said second space and a ring shaped bottom edge of said skirt part, a pressure spring of a compression spring disposed such a manner that an upper end thereof is propped by inner face of the skirt part of the drawn terminal cap and a lower end thereof is held by the temperature detection element through a terminal disk for pressing the element to the inner bottom face of the enclosure, an insulation liner inserted in the enclosure closely adhered to inner face of the enclosure for insulating inner elements, that is, the temperature detection element, the terminal disk and the pressure spring from the enclosure, and an insulation ring cap having a through hole and disposed on the skirt part of the terminal cap, upper peripheral face of said insulation ring cap being held by the cone shaped calking edge with the skirt part thereunder. A temperature detection device of present invention has the above-mentioned structure, therefore a material loss could be saved largely and the device could be obtainable at a very low cost. Furthermore, according to the present invention, angle of the upper face of the insulation ring cap at the part pressed by the calking edge against axis of the terminal cap, namely the angle, which is substantially the angle of the outer face of the calking edge part against the axis of the enclosure, is selected in a range of 100 to 600. In the above-mentioned structure, a positioning operation considering the angular position and a relative spatial position between the insulation ring cap and the calking edge of the enclosure is dispensable, thereby allowing a use of automatic component insertion robot and a sufficient anti-rotation-slip torque between the insulation ring cap and the calking edge of the enclosure is obtainable. Accordingly, a temperature detection device of the present invention is suitable for mass production. Brief Explanation of the Drawing FIG. 1 is a fragmental front view of a temperature detection device of conventional type. FIG. 2 is an exploded perspective view of a temperature detection device of FIG. 1. FIG. 3 is a sectional front view of a temperature detection device of the present invention. FIG. 4 is a graph of a performance curve of anti-rotation-slip torque of an insulation ring cap with respect to a calking angle of the calking edge of the enclosure. Description of the Preferred Embodiment The temperature detection device of present invention comprises: an enclosure of a high thermal conductive substance having a slender cup. shaped part defining a slender first space of a smaller inner diameter and a shallow and wider part defining a shallow and wider second space of a larger inner diameter and connected to the first space, the upper edge of the wider part being formed in cone shaped calking edge, a temperature detection element disposed on an inner bottom face of slender cup shaped part of the enclosure, a drawn terminal cap having a slender top part of smaller diameter for serving as connection terminal and a cone shaped skirt part connected to the slender top part, the drawn terminal cap having continuous hollow space inside the slender top part and the skirt part, an insulation ring cap having a through hole and disposed on the skirt of the terminal cap, upper peripheral face of the insulation ring cap being held by the cone shaped calking edge part, a packing ring disposed between a ring shaped face of the bottom of the second space and a ring shaped bottom edge of the skirt part. As shown in FIG. 3, a metal casing 9 as the enclosure has a slender cup shaped part 901 defining a slender first :space 901 of a smaller inner diameter and a larger depth and a shallow and wider part 902 defining a shallow and wider second space of a larger inner diameter smaller depth and connected to the first space, the upper edge part 903 of the wider part 902 being formed in cone shaped calking edge. A temperature detection element 10 of a temperature-dependent resistor, such as a thermistor, having electrodes 10', 10' on the upper and the lower face thereof is disposed on an inner face of a casing bottom 904 in the slender caup shaped part 901 of the casing 9. A pressure spring 12 presses the temperature detection element 10 to the inner face of the casing bottom 904 through a terminal disk 11 disposed between the pressure spring 12 and the temperature detec tion element 10. An insulation liner 13 inserted in the metal casing 9 is closely adhered to inner face of the casing 9 for insulating inner elements, namely, the temperature detection element 10, the terminal disk 11 and the pressure spring 12 from the metal casing 9. A rubber packing 14 for moisture-proof is disposed on the upper face of a shoulder shaped part at a connecting portion between the smaller inner diameter part 901 of the casing 9 and the larger inner diameter part 902 of the casing 9. A drawn terminal cap 15 for taking a detected signal is disposed at the upper open end of the casing 9. The terminal cap is made of a metal sheet by a drawing process. The drawn terminal cap 15 has a slender top part 151 of smaller diameter for serving as terminal and a cone shaped skirt part 152 connected to the slender top part 151. And further the drawn terminal cap 15 has continuous hollow space inside the slender top part 151 and the skirt part 152. The inner face of the skirt part 152 holds the upper end of the spring 12 and gives pressing force to the spring. The upper end of the insulation liner 13 comes in contact to the inner face of the skirt part 152. An insulation ring cap 16 having a through hole is disposed on the skirt part 152 of the drawn terminal cap 15 in order to fix the drawn terminal cap 15. In this embodiment, the insulation ring cap 16 is made of heat-resistive phenol resin, but any other insulating substance having a sufficient mechanical strength can be used. The insulation ring cap is fixed by calking with the calking edge part 903 of the metal casing 9 resisting an upward pressure of the pressure spring 12, so that the temperature detection element 10, the terminal disk 11, the compression spring 12, the insulation liner 13 are fixed in the space of the slender part 901 by sealing the space by means of the drawn terminal cap 15, thereby assuring good thermal and electric contact of the temperature detection element to the metal casing 9. The primary remarkable advantage of the present invention is that the material loss and manufacturing time can be saved largely and the device could be obtainable at a very low cost by using the drawn terminal cap instead of the conventional solid terminal made from a brass rod worked by machine cutting processing. A drawing processing can provide a smooth surface of-a product, and therefore a good insertion contact between the drawn terminal cap and the corresponding socket thereof is obtainable. Furthermore, since the drawing work is used to make the terminal cap, a viscous, abrasion resistive and smooth material can be selected for the work material, so that few metal trash exists and therefore a good insulation is obtainable. For example, a conventional terminal has been made of brass rod of a material of JIS-C-3601 BD brass which is liable to produce fine metal trash powder when worked and used. And on the contrary, a drawn terminal cap of the present invention is made of more viscous, abrasion resistive and smooth material of JIS-C-2680R-0 brass, which makes substantially no power trash when worked and used. As the top end of the space to contain the spring 12 reaches inside space of the cone shaped skirt part 152 of the terminal cap 15 and the upper end of the pressure spring 12 is stopped by the inner face of the skirt part 152, the upper end of the insulation liner 15 is extended into the space of the cone shaped skirt part 152 of the drawn terminal cap 15 exceeding the upper end of the inner face of the cylindrical slender part 901, and accordingly a reliable insulation is secured even if the length of the insulation liner is slightly shorter than designed length as a result of scatter of size since the liner is longer than a necessary length. Since the drawn terminal cap 15 and the insulation ring cap 16 are made as separate components instead of integral construction by expensive and time taking insert molding processing, further cost saving in manufacturing can be realized. As a special feature, the angle of the upper face of the insulation ring cap 16 at the part pressed by calking edge part 903 against axis of the terminal cap 15, namely the angle e, which is substantially the angle of the outer face of the calking edge part against the axis of the enclosure, is selected in a range of 100 to 600. The inventors made many samples of temperature detecting devices changing the calking angle e within the range of 0 to 900, and measured the antirotatiDn-slippage torque between the drawn terminal and the casing. The measuring result is shown in FIG. 4. As shown in FIG. 4, the anti-rotation-slippage torque takes a peak value of 15 kg-cm at the calking angle e is 300. And the anti-rotation-slippage torque takes smaller value at both the wider or nallower calking angle 6. Generally, a required anti-rotation-slippage torque for such temperature detection device, for example, for use a cooling water temperature detection unit of an automobile engine, is requested to be more than 10 kg-cm. Therefore, it is recognized from FIG. 4 that the suitable calking angle 6 for that required anti-rotation-slippage torque is within 100 to 600.

Claims: What is claimed is 1. A temperature detection device comprising: an enclosure of a high thermal conductive substance having a slender cup shaped part defining a slender first space of a smaller inner diameter and a shallow and wider part defining a shallow and wider second space of a larger inner diameter and connected to said first space, the upper edge of said wider part being formed in cone shaped calking edge part, a temperature detection element disposed on an inner bottom face of said slender cup shaped part of said enclosure, a drawn terminal cap having a slender top part of smaller diameter for serving as terminal and a cone shaped skirt part connected to said slender top part, said drawn terminal cap having continuous hollow space inside said slender top part and said skirt part, an insulation ring cap having a through hole and disposed on said skirt of said terminal cap, upper peripheral face of said insulation ring cap being held by said cone shaped calking edge, and a packing ring disposed betwedn a ring shaped face of the bottom of said second space and a ring shaped bottom edge of saidskirt part. 2. A temperature detection device in accordance with claim 1, which further comprises an insulation liner inserted in said enclosure with the top end thereof reaching to contact an inner face of said cone shaped skirt part of said drawn terminal cap. 3. A temperature detection device in accordance with claim 1, wherein an angle of the upper face of said insulation ring cap at the part pressed by said calking edge part against axis of said terminal cap, namely the angle, which is substantially the angle of the outer face of said calking edge part against the axis of said enclosure, is selected in a range of 100 to 600.

Inventors: ISHIKAWA, KAZUO, SHIBUYA, KATSUJI
Applicants: MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1981
Main classification: G01K7
IPC codes: G01K7