JP3420190B2 - Manufacturing method of mold unit component of composite sensor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a method for manufacturing a mold unit component of a composite sensor suitable for detecting a liquid temperature of, for example, an engine cooling system for an automobile. 2. Description of the Related Art A composite sensor for detecting a liquid temperature in an automobile engine cooling system is constructed by using a thermistor having two different characteristics in the same case. That is, the first is used as a temperature sensor (first thermistor) for an electronic control unit (ECU) used for controlling a fan motor, fuel injection, idle speed, and the like. The second is used as a temperature sensor (second thermistor) for a water thermometer for displaying the temperature of the cooling water of the engine on the instrument panel of the driver's seat. The second thermistor for this meter has a donut shape,
In many cases, the first thermistor is arranged and combined at the center thereof. In the composite sensor described above, the second thermistor generates a large amount of heat due to self-heating for the reason described later, and due to the interference of the heat, the characteristics of the first thermistor cannot be maintained at the initial value and change. This change should not originally occur for the engine control by the ECU. Many proposals have been made for this problem, but no best product has yet been found. Here, the self-heating phenomenon of the second thermistor will be described. Generally, the aforementioned thermistor is NT
The C type is adopted, and its characteristic is that the electric resistance decreases as the temperature rises. As for the current flowing through the first thermistor, the current required for controlling the ECU may be very small, and its form is small. On the other hand, the current flowing through the second thermistor has a large power for obtaining the rotational force of the meter needle and a large swing width, and therefore, the form becomes large. Therefore, the arrangement characteristic of these two thermistors is that the first thermistor, which is smaller than the second thermistor, is disposed at the tip of the case. Moreover, the first thermistor is disposed through the hole of the donut-shaped second thermistor. When current flows through the thermistor, which is a resistor, Joule heat is generated, and the temperature of the second thermistor requiring a large current increases. Generating Joule heat in this way is called self-heating. As a countermeasure against self-heating, Japanese Patent Application Laid-Open No. 7-29
Japanese Patent No. 4338 discloses a heat radiating means having a plurality of irregularities 4 provided outside a required portion of the case 1 and a heat radiating means in which a heat transfer material (silicon oil) 16 is sealed (filled) in an inner space of the case 1. A corresponding technique is disclosed. Also, Japanese Patent Application Laid-Open
Japanese Patent Application Laid-Open No. 7-29433 discloses a method disclosed in
Similarly to the means disclosed in Japanese Patent Application Publication No. 8-118, there are disclosed heat dissipation means of route A, route B and route C of a heat dissipating means provided with a heat dissipating portion 12 (corresponding to the above-mentioned uneven shape) outside a required portion of the case 4. ing. And there is an explanation that the solution of these means is that the silicone oil 13, which is a filling medium for dissipating heat, functions. [0005] As described above, in the disclosed example, the interior space of the case and the periphery of the two thermistors are filled with silicone oil as a heat transfer material. Here, in the internal space of the case, the connection area is connected from the arrangement area of the first thermistor to the arrangement area of the coil spring for supporting the second thermistor, and the silicon oil as the heat transfer material existing in this space is endlessly and horizontally. Mobile deployment is possible. In such a case interior space,
The heat from the second thermistor due to self-heating is transmitted to everything including the first thermistor via the silicone oil. As a result, the first thermistor may be affected by heat. The main reason for using silicon oil is that the first thermistor is embedded in the molded unit, and the gap formed between the first thermistor and the metal case serving as the sheath is thermally conductive with silicon oil. It is thought that it is necessary to connect to. [0006] Further, silicon oil must be used because expensive springs (coil springs) are used. That is, as shown in FIG.
Is composed of split dies 41 and 42 that form the outer shape of the mold unit body, and movable dies 43 that allow finished products and mold insert parts to be taken in and out of the split dies and that form a connector part of the mold unit. Is done. The movable die 43 has a pinching function that can hold the terminal, and as shown in the drawing, all the insert-related parts are supported by the terminal portion. Among the insert-related components, in particular, the first thermistor side has terminals a,
b, and is assembled into a hole of the electrode plate f integrated with another terminal c, and then attached to each terminal holding portion of the movable mold 43. FIG. 6 shows a state of waiting for molding after the mounting in this manner, and the supporting structure has nothing to support other than the terminal. In such a supporting state, a high-temperature and high-pressure synthetic resin is injected. At that time, since the electrode plate f receives the injection pressure over the entire surface of the donut-shaped disk, the electrode plate f is violently moved back and forth and left and right due to the rebound pressure, and in some cases, it is deformed, and from the reference plane. It is anticipated that a variation will occur in the area of the squareness Q0 at the height H0. Also, on the first thermistor side, the lead wire is moved endlessly and horizontally by receiving the injection pressure, and in some cases, the lead wire comes off, the spherical portion is broken, or the lead wire is pulled in and the spherical portion is pulled. The stop position is large, and problems such as variations may be considered. As a countermeasure against such a problem, an electrode plate f
On the side, make the length L of the supporting arm member as short as possible,
It is assumed that the strength has been achieved. However, even with this, the dimensions of the height H0 and the perpendicularity Q0 from the reference plane were not stable. Further, on the first thermistor e side including the lead wire, at present, there is no countermeasure. By the way, the mounting arrangement of the thermistor in the case is inevitably determined by the position where heat sensing is best when the thermistor is mounted on the engine. On the other hand, the position of the terminal connected to the harness is also determined in consideration of the related surrounding conditions. As a result, the space between the second thermistor and the electrode plate f greatly opens. The spring (coil-shaped spring) in the conventional product serves to connect the large opening. Other functions of the coil spring include pressing of the second thermistor and electrical connection with the connector. More importantly, the height H0 of the electrode plate f from the above-described reference plane is more important. ,
There is variation relief for the dimension of the squareness Q0. That is, the flexibility characteristic of the spring absorbs the variation. [0010] Further, for expensive springs, as a measure against the heat radiation path C route disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 7-318434, the diameter of the spring may be increased,
There are proposals such as adopting a method of increasing the thickness of the electrode plate to increase the amount of heat conducted to the connector side. However, even with this method, there is no way to perform the above-mentioned transfer of heat in the mobile development of silicone oil. Increasing the wire diameter of the spring or increasing the thickness of the electrode plate increases not only the weight of the product but also the cost. Also, if the spring diameter is increased due to the increase in the wire diameter of the spring, it is considered that many parts such as the strength of parts and the ease of assembly around the spring are affected. [0011] As described above, the conventional product is designed to cope with the interference of heat on the first thermistor due to the self-heating of the second thermistor. However, as described above, there is a problem with silicon oil, which is a heat transfer material filled in the internal space of the case, and the structure has to use an expensive coiled spring, or the wire of the expensive coiled spring has to be used. There is a problem to be solved by increasing the diameter, and further, the yield in the molding operation is poor. An object of the present invention is to provide a composite sensor with relatively stable product performance. It is a further object of the present invention to provide a mold unit component having a high molding yield. [0014] In order to solve the above problems, the invention according to claim 1 is a method of manufacturing a mold unit component of a composite sensor. For example, as shown in FIG. 5, a split mold 40 constituting a mold 400 for injection molding.
In a mold space for molding a mold unit 2 to be assembled in a metal case 1 containing two thermistors 4 and 7 having different characteristics and formed by sliding molds 1 and 402 and a sliding mold 403 disposed therebetween. The support member 9 is disposed at the entrance step 405 of the small diameter portion 406 with the bottom where the first thermistor 7 is disposed, and the plurality of mold insert parts 70 held by the sliding die 403 by the support member 9. A characteristic is that the synthetic resin is injected and the mold unit 2 is molded in a state in which each of the mold units 80 is held. According to the first aspect of the present invention, each of the plurality of mold insert parts held in a sliding mold by the support member arranged at the entrance step of the small diameter portion with the bottom in which the first thermistor is arranged. While holding, the synthetic resin is injected into the mold space to form the mold unit, so the multiple mold insert parts firmly held at the upper and lower two places by the sliding mold and the support member are made of high-temperature and high-pressure synthetic resin. The molding can be performed stably without being shaken even by the injection of. Embodiments of the present invention will be described below in detail with reference to the drawings. [First Embodiment] As shown in FIGS. 1 to 3, the main components of this embodiment are a metal case 1, a mold unit 2, a wave washer 3, a second thermistor 4, a flat washer. 5, first thermistor 7, sleeve 1
0, composed of a gel-like holding member 11. Metal case 1
Has a small-diameter portion 1a with a bottom that is in direct contact with the cooling water and transmits the temperature to the inside. The mold unit 2 includes terminals (conductive members) 6a, 6b, 6c and a first thermistor 7. The wave washer 3 has conductivity and absorbs assembly dimensional errors. The second thermistor 4 has a donut shape. The flat washer 5 has conductivity and supports the sitting state of the second thermistor 4. The sleeve 10 is made of an electrically insulating material. The gel-like holding member 11 is prepared in consideration of holding of the spherical portion of the first thermistor 7 and heat transfer from water temperature. The molding unit 2 is molded by a molding die 400 shown in FIG. In FIG. 5, 9 is a mold 4
Inlet step 4 of small diameter portion 406 with bottom of mold space 00
It is a support member fitted to 05. The primary function of the support member 9, the support in two positions of the mold insert part 70, 80, high-precision positioning of the electrode plate 8, the first support during the molding
Protection of the mist 7. The mold 400 is divided into molds 401 and 40 for forming the outer shape of the mold unit 2.
2 and a terminal 6a, 6b, 6c holding function,
Further, it is composed of a sliding mold 403 forming a connector part.
In the space (mold space) of the mold unit 2 of the molding die 400, in addition to the support member 9 arranged on the step portion 405, three terminals 6a held by the sliding die 403,
6b, 6c, a first thermistor 7, a donut-shaped electrode plate 8, and the like are arranged. The support member 9 has a cylindrical shape, and has an upper and lower large-diameter portion 9c and a small-diameter portion 9d with a stepped portion 9b as a boundary, as shown in an enlarged manner in FIG. The small-diameter portion 9 engages with a central hole 8 a of the electrode plate 8, and further has split molds 401 and 402.
With the small-diameter portion 406. After the electrode plate 8 is held, it does not come off by the stepped portion 9b. Also,
In the end face of the support member 9, two lead wire wiring through holes 9a which are evenly distributed in parallel with the axis are opened. Mold 4
Incorporation into 00 is performed after sub-assembly. That is, after the lead wires (conductive members) 7a and 7b of the first thermistor 7 are incorporated into the through holes 9a of the support member 9, a mold insert component 70 to which the terminals 6a and 6b are connected is prepared. On the other hand, the electrode plate 8 and the terminal 6c are
It is prepared as an integral mold insert part 80 via the extension arm member 8b. Each terminal 6a, 6b, 6c is attached to the holding portion 404 of the sliding die 403 while the support member small diameter portion 9d is inserted into the electrode plate central hole 8a of the mold insert components 70, 80 thus prepared. Subsequently, by continuing the mold clamping operation,
The setting completion state as shown in FIG. 5 is obtained. In this state, the mold insert component 70 is firmly held at two places between the terminals 6a, 6b and the leads 7a, 7b.
Numeral 0 is firmly held at two places of the terminal 6 and the electrode plate 8. Therefore, even if the high-temperature and high-pressure synthetic resin is injected, the mold insert parts 70, 8
0 does not swing and stable injection molding can be performed. The first thermistor 7 is not affected by the injection molding at all because the support member 9 prevents the flow of the synthetic resin. As described above, in the conventional product, many problems related to the first thermistor have occurred, but this can be solved. Further, in the conventional product, the length L of the arm member supporting the electrode plate is limited, but in the product of the present invention, there is no problem even if the necessary and sufficient length is planned. Here, the function of the support member 9 during injection molding will be described in detail. When the synthetic resin of the fluid by injection flows into the mold unit space of the molding die 400, the support member 9 is pressed by the force and pressure, and
The piston moves to the first thermistor 7 side as if it operates. By this movement, the electrode plate 8 is pressed only to the step portion 405 of the separation dies 401 and 402, and the height H1 and the squareness Q
1 is forcibly determined. Then, by solidifying the injected synthetic resin, its dimensions can be maintained for a long time with high accuracy. Incidentally, the height H1 indicates a dimension from the step portion 1e serving as a reference surface when the mold unit 2 is assembled with the metal case 1. In FIG.
There is a relationship of H1 = H2 = H3. However, H2 is the dimension from the reference plane to the step 1d, H3 is the wave washer 3,
This is the total thickness of the thermistor 4, the flat washer 5, and the like. Assuming that the arrangement portion of this part is the H3 zone, the configuration and arrangement in the H3 zone are the wave washer 3, the second thermistor 4, and the flat washer 5, whereas the flat washer 5, the second thermistor 4, and the wave Even if it is the washer 3, the wave washer 3, the second thermistor 4, the wave washer 3, the wave washer 3, the second thermistor 4, the second thermistor 4, the wave washer 3, or the like. Absent. In any of the patterns, the wave washer 3 does not come off. The support member 9 buried in the molded mold unit 2 after molding is in a fixed state in which the arm member is similarly sandwiched between the buried electrode plate 8 and a synthetic resin as a molding material. Never. The material of the support member 9 and the material of the mold unit 2 are the same synthetic resin, and are commercially available nylon (PA66 GF30 Sumitomo Wiring Systems 6189)
−0486) is desirable. Then, the form of the first thermistor 7 in the molded unit 2 after the molding is removed is in a state of being exposed to the outside from the end face of the support member 9 via the lead wires 7a and 7b. The diameter of the upper surface side (larger diameter portion 9c side) of the wiring through hole 9a of the support member 9 is such that the lead wires 7a and 7b of the first thermistor 7 can be passed lightly without bending. At the time of injection molding, the size is set so that the synthetic resin in a flowing state does not flow out to the opposite side. The longitudinal section of the wiring through hole 9a may be tapered in the middle as long as the hole diameter of the entrance is secured. When the mold unit 2 completed by the above-described process is combined with the metal case 1, a gel-like holding member 11 must be prepared. That is, the sleeve 1 is attached to the step 1d at the back of the hollow portion of the metal case 1.
The flat washer 5, the second thermistor 4, the wave washer 3 and the like are successively incorporated from the inside of the sleeve 10 from behind. Next, silicon material (commonly known as silicon bond) is injected into the small-diameter portion 1a with the bottom in a state where the spherical portion of the first thermistor 7 can sufficiently surround the metal case 1 while the standing posture of the metal case 1 is maintained. After the injection, while the liquid state of the silicon material can be maintained, the mold unit 2
Is assembled through the opening, and is caulked hermetically at the step 1e to be integrated with each other. It is necessary to maintain the above-mentioned standing posture of the metal case 1 until the injected silicon material gels. The gel-like holding member 11 described above is
In addition to gently holding the spherical part of the thermistor 7,
The heat transfer from the metal case 1 that senses the water temperature is greatly improved. Note that the composition of the gel-like holding member 11 before the injection should not contain a solvent of a volatile component because it gels after airtightly caulking. Solventless or two-pack silicon materials are optimal. On the upper surface of the gel-like holding member 11, a heat insulating space 12 is formed between the lower surfaces of the supporting members 9. That is, by providing the heat insulating space 12 between the first thermistor 7 and the second thermistor 4, an environment is constructed in which heat is not directly transmitted between the two, regardless of radiant heat.
In the above, the neck length H in the mold unit 2
And the dimensional accuracy of the angle Q are high and stable made in the manufacturing process. Due to this accuracy, not only can the wave washer 3 be used in the contact area, but also from the electrode plate 8 to the wave washer 3, the second thermistor 4, the flat washer 5 , and the step 405 of the metal case 1. Since the degree of contact between the contact surfaces increases, a heat transfer material such as silicon oil used in the disclosure of the related art is not required. Moreover,
The wave washer 3 is inexpensive and lightweight. As described above, the expansion / contraction ability of the wave washer 3 used in the present invention is extremely smaller than the expansion / contraction ability (displacement amount) of the spring (coil spring) used in the disclosed example of the prior art. However, as described above, it is possible to use the apparatus while ensuring the accuracy. The wave washer 3 can be used because the electrical connection with the connector side and the pressing function of the second thermistor 4 are maintained as before,
In addition, the mold unit 2 having a large heat capacity is held on the side surface of the second thermistor 4. This contributes to eliminating the problem of heat interference due to self-heating. That is, the second
The heat from the thermistor 4 is applied to the wave washer 3
To the electrode plate 8 and the arm member 8b, and further spread to the entire mold unit 2 having a large volume for embedding them. Due to this dispersion, the heat transmitted to the first thermistor 7 is greatly reduced. Next, the effects obtained by the present invention will be listed. 1) Cost measures In molding the mold unit 2, the mold insert parts 70 and 80 are supported at two places using the support member 9, so that the mold portion can be extended to the electrode plate 8. An inexpensive wave washer 3 has become available. That is, it is not necessary to use an expensive spring like a conventional product. 2) Countermeasures against heat interference Since the set position accuracy of the electrode plate 8 is increased by supporting the mold insert parts 70 and 80 at two places by the support member 9, the contact surface of the H3 zone part surrounding the second thermistor 4 is improved. Greatly improved the degree of contact. Further, since the wave washer 3 can be used in the contact area, the second
The heat was absorbed by holding the mold unit 2 having a large heat capacity on the side surface of the thermistor 4, and the flow of heat to the first thermistor 7 was prevented. The spherical portion of the first thermistor 7 is exposed from the mold portion of the mold unit 2, is held by the gel-like holding member 11, and is provided with a heat insulating space 12 above the first thermistor 7. 2
Heat is not easily transferred directly between the thermistors 4. 3) Countermeasures against silicon oil The precision of the set position of the electrode plate 8 is increased by supporting the mold insert parts 70 and 80 at two places by the support member 9, and
The heat transfer effect is great because the degree of contact of the contact surface of the H3 zone component surrounding the thermistor 4 is greatly improved. Also, the spherical portion of the first thermistor 7 is
Is fixed to the stepped small-diameter portion 1a with the gel-like holding member 11, the integration is strong, and the heat transfer effect is large. Since the conventional product had a molded product inserted into the case as a sheath, a gap was created between the two, and it was necessary to close the gap with silicone oil, whereas the product of the present invention had no gap No silicone oil is required. [Second Embodiment] In this embodiment, as shown in FIG. 4, a bottom surface is provided on a lower surface side of a support member 90 corresponding to the above-described support member 9 and on a side facing the heat insulating space 12. A space 90a is formed. By forming the bottomed space 90a above the heat insulating space 12, the above-described heat insulating space function is further expanded. Of course, in addition to the above-described embodiments, specific detailed structures and the like can be appropriately changed. According to the first aspect of the present invention, a plurality of mold insert parts which are firmly held at two upper and lower positions by a sliding die and a support member are made of a high-temperature and high-pressure synthetic resin. The molding can be performed stably without being shaken even by the injection of. Therefore, it is possible to provide a mold unit component having a high molding yield.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional front view showing a configuration of a composite sensor according to a first embodiment of the present invention, and is a cross-sectional view taken along the line AA of FIG. FIG. 2 is an enlarged view of a thermistor arrangement portion in FIG. FIG. 3 is a plan view showing the arrangement of terminals and the form of a connector, as viewed from above in FIG. 1; FIG. 4 is a longitudinal sectional front view showing a configuration of a composite sensor according to a second embodiment of the present invention, in which a thermistor arrangement portion is shown in an enlarged manner. FIG. 5 is a vertical sectional front view showing a state before molding, in which a molding die of a molding portion of the product of the present invention and a mold insert component therein are arranged. FIG. 6 is a vertical sectional front view showing a state before molding, in which a molding die of a molding part of a conventional product and a mold insert part therein are arranged. [Description of Signs] 1 Metal case 1a Small diameter portion 2 Mold unit 3 Wave washer 4 Second thermistor 5 Flat washer 6a, 6b, 6c Terminal (conductive member) 7 First thermistor 7a, 7b Lead wire (conductive member) 8 Electrode Plate 8a Central hole 9 Support member 9a Lead wire wiring through hole 9b Stepped portion 9c Large diameter portion 9d Small diameter portion 10 Sleeve 11 Gel-like holding member 12 Heat insulation space 70, 80 Mold insert component 90 Support member 400 Mold 401, 402 Split type 403 Sliding type 405 Inlet step 406 Small diameter part with bottom

Claims (1)

(1) A metal for housing two thermistors having different characteristics, which is formed by a split mold constituting a mold for injection molding and a sliding mold disposed therebetween. In a mold space for molding a mold unit to be assembled in a case, a support member is disposed at an entrance step of a small-diameter portion with a bottom in which a first thermistor is disposed. A method of manufacturing a mold unit component of a composite sensor, comprising injecting a synthetic resin to form a mold unit while holding a plurality of held mold insert components.