JP4633954B2 - Electronics - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic device having a waterproof function and a cable fixing function in a cable lead-out portion of a case.
[0002]
[Prior art]
Conventionally, as a means for waterproofing and fixing cables at the cable lead-out part of the case in electronic equipment, waterproofing is achieved by applying an adhesive to the gap between the insertion hole as the cable lead-out part and the cable, and the cable is prevented from being detached. And a method of fixing a cable by projecting and forming a cylindrical portion as a cable lead-out portion on the case and covering the cylindrical portion with a cap so that the cylindrical portion is elastically deformed in the reduced diameter direction.
[0003]
[Problems to be solved by the invention]
The former method has a problem that when placed in a high-temperature environment, the adhesive peels off due to the influence of heat, and the waterproof function and the fixing function are impaired.
On the other hand, in the latter method, when the case and the cylindrical portion are made of a hard resin material, the cylindrical portion is hardly elastically deformed only by being covered with a cap. It is necessary to make it the form divided into. However, if the slit is provided, the waterproofness of the cylindrical portion cannot be maintained, and therefore a ring-shaped sealing member that is a separate component from the case and the cap must be used. Therefore, this method has a problem that not only the number of parts is increased and the part cost is increased, but also the number of assembling steps is increased and the assembly cost is increased.
[0004]
The present invention has been made in view of the above circumstances, and an object of the present invention is to enable use in a high-temperature environment and reduce the number of components in an electronic device having a waterproof function and a cable fixing function in a cable lead-out portion.
[0005]
[Means for Solving the Problems]
According to the first aspect of the present invention, a cylindrical lead-out portion is provided on the outer surface of the case so as to lead the cable out of the case to the outside, and a cylindrical cap is fitted on the cylindrical lead-out portion. The case and the cylindrical lead-out part are integrally formed of the same material, and the cylindrical lead-out part has a thin part thinner than the thickness of the case over the entire circumference, and the circumference of the thin part is An annular ridge is formed over the entire circumference of the surface, the cap is configured to be more rigid than the cylindrical lead-out portion, and in the annular region along the ridge, the cylindrical lead-out portion is By being pushed in the radial direction at the inner circumference of the cap that is fitted on the cylindrical lead-out portion, the diameter of the cap is reduced so as to bite into the outer circumference of the cable.
[0006]
According to a second aspect of the present invention, in the first aspect of the invention, the protrusion is formed on the outer periphery of the cylindrical lead-out portion, and the protrusion has a tapered surface.
A third aspect of the present invention is the invention according to the first or second aspect, wherein the cable has a plurality of conductors inserted through the protective tube and the protective tube penetrated into the cylindrical lead-out portion. In the protective tube, a wedge member that presses the protective tube against the inner periphery of the cylindrical lead-out portion is fitted.
[0007]
According to a fourth aspect of the present invention, in the third aspect of the present invention, a circumferential concavo-convex portion that bites into the inner periphery of the protective tube is formed on the outer periphery of the wedge member.
[0008]
[Action and effect of the invention]
[Invention of Claim 1]
When the cap is externally fitted to the cylindrical lead-out portion, the cylindrical lead-out portion is reduced in diameter over the entire circumference and bites into the outer periphery of the cable, and by this biting action, the inner periphery of the cylindrical lead-out portion and the outer periphery of the cable The gap is waterproofed, and the cable is fixed to the tubular lead-out portion in a secured state. In the present invention, since no adhesive is required, there is no possibility that the waterproof function and the cable fixing function are impaired even in a high temperature environment. In addition to the case, only the cap is used as a component other than the case, and the number of components can be reduced as compared with a structure that requires a seal member in addition to the cap.
[0009]
[Invention of claim 2]
When the cap is fitted on the cylindrical lead-out portion, the inner periphery of the cap pushes the ridge in the radial direction to deform the cylindrical lead-out portion in a reduced diameter. In the process of externally fitting the cap, the cap abuts against the taper surface, and the cylindrical lead-out portion is gradually reduced in diameter by the inclination of the taper surface. There is no direction catching, and the outer fitting of the cap and the diameter reduction of the cylindrical lead-out portion are performed smoothly.
[0010]
[Invention of claim 3]
Since the wedge member is fitted into the protective tube and the protective tube is pressed against the inner periphery of the cylindrical lead-out portion, the waterproof function and the retaining function are also exhibited by the pressing action.
[Invention of claim 4]
When the uneven portion on the outer periphery of the wedge member bites into the inner periphery of the protective tube, the wedge member is prevented from being detached from the protective tube.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment 1]
A first embodiment of the present invention will be described below with reference to FIGS.
[0012]
The electronic apparatus according to the present embodiment is a liquid leakage sensor A that is disposed on a flooded surface F such as a floor under a pipe and optically detects the presence or absence of liquid leakage on the flooded surface F. The liquid leakage sensor A includes a case 10 having an open top surface, a lid 11 for closing the opening of the case 10 in a liquid-tight state, a circuit board 12 accommodated in the case 10, and a cable 13 connected to the circuit board 12. And is configured. The case 10 is made of a translucent resin material, and a detection surface 14 is formed on the lower surface of the case 10 so as to face the surface to be submerged F with a small gap S therebetween. Further, the light emitting unit 15 and the light receiving unit 16 are attached to the lower surface of the circuit board 12 so as to be positioned above the detection surface 14.
[0013]
When there is no leakage of liquid and no liquid is present on the surface to be submerged F, the light emitted from the light emitting unit 15 is totally reflected on the detection surface 14 and received by the light receiving unit 16. On the other hand, when the liquid leaks onto the surface to be submerged F and the leaked liquid enters the gap S between the surface to be submerged F and the detection surface 14, the light emitted from the light emitting unit 15. Most of the light passes through the detection surface 14 and the liquid, is reflected on the surface F to be submerged, passes through the liquid and the detection surface 14 again, and is received by the light receiving unit 16. The intensity of the light is weak compared to the case where the light is totally reflected by the detection surface 14. The intensity of light received by the light receiving unit 16 is sent as an electrical signal to a detection circuit (not shown) via the cable 13, and the detection circuit detects the presence or absence of liquid leakage based on the sent electrical signal. Is done.
[0014]
Next, the waterproof means and the cable fixing means in the cable lead-out portion of the leak sensor A will be described.
The case 10 is made of a relatively soft and relatively high heat resistance synthetic resin material such as polypropylene, Teflon, polyethylene, and nylon. A cylindrical lead-out portion 17 whose inside is an insertion hole 18 protrudes from the outer surface of the case 10, and the cable 13 inserted into the insertion hole 18 is led out of the case 10. The cable 13 will now be described. The cable 13 has a structure in which three conductors 13B are inserted into a protective tube 13A made of synthetic resin, and the end of the protective tube 13A is slightly inserted into the case 10 from the insertion hole 18. A conductor 13 </ b> B extending from the end of the protective tube 13 </ b> A is connected to the circuit board 12.
[0015]
The inner diameter dimension of the insertion hole 18 of the cylindrical lead-out portion 17 in a state before the leakage sensor A is assembled is a constant dimension over the entire length in the axial direction (the protruding direction of the cylindrical lead-out portion 17). On the other hand, the outer periphery of the cylindrical lead-out part 17 is composed of a large diameter part 19 on the side close to the case 10 and a small diameter part 20 on the side farther from the case 10 than the large diameter part 19. The large-diameter portion 19 is formed with a pair of left and right retaining projections 21 positioned at the leading edge thereof, and a pair of upper and lower axially extending guide ribs 22. . Further, on the outer periphery of the small-diameter portion 20, an annular ridge 23 is continuously formed over the entire periphery. The maximum outer diameter dimension of the protrusion 23 is set smaller than the outer diameter dimension of the large diameter portion 19. The outer peripheral surface of the protrusion 23 has a constant-diameter surface 23A whose outer diameter dimension is constant in the axial direction, and continues to the front side with respect to the constant-diameter surface 23A, and the outer diameter dimension gradually decreases toward the front. It is comprised from the taper surface 23B. Note that the protruding end portion 24 positioned further forward than the tapered surface 23 </ b> B in the small diameter portion 20 has the smallest outer diameter in the small diameter portion 20.
[0016]
A cylindrical cap 25 is fitted on the cylindrical lead-out portion 17. The cap 25 is made of a heat-resistant synthetic resin material and has higher rigidity than the small-diameter portion 20 of the cylindrical lead-out portion 17. In the present embodiment, a synthetic resin material having a higher rigidity than the cylindrical lead-out portion 17 (case 10) is selected as a means for increasing the rigidity, and the radial direction is smaller than the small-diameter portion 20 of the cylindrical lead-out portion 17. The wall thickness is increased. Note that when a resin material having a considerably higher rigidity than that of the cylindrical lead-out portion 17 is selected, the thickness of the cap 25 can be made approximately the same as the thickness of the small-diameter portion 20.
[0017]
The outer diameter of the cap 25 is constant over the entire length in the axial direction. On the other hand, the inner periphery of the cap 25 has an enlarged diameter portion 26 which is fitted to the large diameter portion 19 of the cylindrical lead-out portion 17 without leaving a gap in the radial direction, and a small diameter portion 20 of the cylindrical lead-out portion 17. And a corresponding reduced diameter portion 27. The cap 25 is formed with a pair of left and right retaining holes 28 penetrating from the outer periphery to the enlarged diameter portion 26 and a pair of upper and lower guide grooves 29 elongated in the axial direction. Further, the inner diameter dimension of the reduced diameter portion 27 is constant over almost the entire length thereof, is larger than the outer diameter dimension of the projecting end portion of the cylindrical lead-out portion 17, and is outside the constant diameter surface of the protrusion 23. The dimension is set smaller than the diameter. Further, a tapered guide surface 30 whose diameter gradually increases toward the enlarged diameter portion 26 is formed at the end of the reduced diameter portion 27 on the enlarged diameter portion 26 side. An annular pressing portion 31 having an inner diameter dimension substantially the same as the outer diameter dimension of the protruding end portion of the small diameter portion 20 is formed at the end portion of the reduced diameter portion 27 opposite to the guide surface 30. ing.
[0018]
Further, a wedge member 32 is attached to the cable 13. The wedge member 32 is fitted into the protective tube 13A from the end of the protective tube 13A facing the case 10, and in the fitted state, the three conductors 13B are arranged on the outer periphery of the wedge member 32 as shown in FIG. The wedge member 32 presses the inner periphery of the protective tube 13A radially outward via the three conductors 13B. Further, the leading end portion of the wedge member 32 is a tapered guiding portion 33. Furthermore, a circumferential concave portion 34 and a convex portion 35 are formed on the outer periphery of the wedge member 32 continuously over the entire circumference.
[0019]
Next, the assembly procedure of the leak sensor A of this embodiment will be described.
First, the cable 13 is inserted through the cap 25 as shown in FIG. 2, and the terminal portion of the cable 13 is inserted into the insertion hole 18 of the cylindrical lead-out portion 17 from the outside as shown in FIG. . Next, the position of the end of the protective tube 13A in the case 10 is determined. In this state, as shown in FIG. 1, the cap 25 is externally fitted to the cylindrical lead-out portion 17, and the wedge member 32 is placed in the case 10. Is inserted into the protective tube 13A. Either the outer fitting of the cap 25 or the fitting of the wedge member 32 may be performed first.
[0020]
When the cap 25 is externally fitted, when the guide rib 22 and the guide groove 29 are fitted, the cap 25 is positioned in the circumferential direction with respect to the tubular lead-out portion 17, and when the cap 25 is normally externally fitted, the cap 25 is removed. The cap 25 is fixed to the tubular lead-out portion 17 in a state where the cap protrusion 21 and the retaining hole 28 are locked.
In the process of externally fitting the cap 25, the guide surface 30 at the end of the reduced diameter portion 27 is in contact with the tapered surface 23 </ b> B of the protrusion 23 obliquely, and the inclination between the cap 25 and the protrusion 23 is caused by the inclination. Thus, the external fitting operation smoothly proceeds without being caught. Here, since the small-diameter portion 20 of the cylindrical lead-out portion 17 is lower in rigidity than the cap 25, as the outer fitting of the cap 25 progresses, the inclination of the guide surface 30 and the tapered surface 23 </ b> B causes the small-diameter portion 20. Of these, the annular region along the ridge 23 is pushed by the reduced diameter portion 27 on the inner periphery of the cap 25 and gradually decreases in diameter. When the cap 25 is normally fitted, the reduced diameter portion 27 of the cap 25 presses the constant diameter surface 23A of the protrusion 23, and the reduced diameter deformation amount of the small diameter portion 20 is maximized. In this state, as shown in an enlarged view in FIG. 8, the annular portion corresponding to the protrusion 23 in the inner periphery of the small diameter portion 20 bites uniformly over the outer periphery of the protective tube 13 </ b> A of the cable 13. It becomes like this. This biting action eliminates the gap between the inner circumference of the cylindrical lead-out portion 17 and the outer circumference of the cable 13 and is waterproofed in a liquid-tight state, and the axial lead-out action caused by the biting causes the cylindrical lead-out portion 17. On the other hand, the cable 13 is restricted from moving in the axial direction and fixed in a retaining state.
[0021]
When the annular region of the small-diameter portion 20 where the ridges 23 are formed is deformed and deformed, the reaction end force causes the projecting end 24 ahead of the ridges 23 to undergo diameter-expanding deformation. Even if this occurs, the protruding end 24 is pressed by the pressing portion 31 of the cap 25 so as not to increase in diameter, so that the protruding end 24 does not deform and expand.
Further, in a state where the wedge member 32 is fitted in the protective tube 13A, as shown in FIG. 9B, the wedge member 32 directs the protective tube 13A toward the inner periphery of the cylindrical lead-out portion 17 via the conductor 13B. This pressing action eliminates the gap between the outer circumference of the protective tube 13A and the inner circumference of the cylindrical lead-out portion 17 and is waterproofed in a liquid-tight state, and the cylindrical lead-out portion 17 is caused by friction caused by the press. The movement of the protective tube 13A in the axial direction is restricted.
[0022]
Further, since the concave portion 34 and the convex portion 35 formed on the outer periphery of the wedge member 32 bite into the inner circumference of the protective tube 13A, the hook member 32 is prevented from coming off from the protective tube 13A due to the catching action caused by this biting. ing.
Further, waterproofing and fixing by the wedge member 32 are performed at the large diameter portion 19 of the cylindrical lead-out portion 17, and waterproofing and fixing by the cap 25 are performed at the small diameter portion 20. That is, since the cap 25 and the wedge member 32 are waterproof and the cable 13 is fixed at two locations separated in the axial direction, the waterproof function and the reliability of the fixing function are high.
[0023]
After the assembly of the cap 25 and the wedge member 32 is completed as described above, the conductor 13B is connected to the circuit board 12, the circuit board 12 is fixed in the case 10, and the lid 11 is attached to the opening of the case 10. Fix it in a liquid-tight state. Thus, the assembly of the leak sensor A is completed.
As described above, in the present embodiment, when waterproofing and cable fixing are performed in the cylindrical lead-out portion 17 that is the lead-out portion of the cable 13, no adhesive is required, so that the waterproof function and the cable fixing function can be achieved even in a high-temperature environment. There is no risk of damage. Further, the minimum necessary component used for other than the case 10 is only the cap 25 fitted on the cylindrical lead-out portion 17, and the number of components is smaller than that of a structure requiring a seal member in addition to the cap 25. There is little to do.
[0024]
In addition, since the tapered surface 23B is formed on the outer periphery of the ridge 23, there is no axial catch between the cap 25 and the ridge 23, and the outer fitting operation of the cap 25 and the contraction of the cylindrical lead-out portion 17 are prevented. Radial deformation can be performed smoothly.
Further, since the wedge member 32 is provided in addition to the cap 25 as means for waterproofing and fixing the cable 13, higher waterproof function and fixing function are exhibited.
Moreover, since the concave portion 34 and the convex portion 35 on the outer periphery of the wedge member 32 are bitten into the inner periphery of the protective tube 13A, the wedge member 32 can be prevented from being detached from the protective tube 13A.
[0025]
[Embodiment 2]
Next, a second embodiment of the present invention will be described with reference to FIG.
In the liquid leakage sensor B of the second embodiment, the means for fixing the cap 42 to the cylindrical lead-out portion 40 is configured differently from the first embodiment. That is, in the second embodiment, in place of the locking means by the retaining protrusion and retaining hole of the first embodiment, it is formed on the inner periphery of the cap 42 with respect to the male screw portion 41 formed on the outer periphery of the cylindrical lead-out portion 40. The cap 42 is externally fitted to the cylindrical lead-out portion 40 by screwing the female screw portion 43 that has been made. Since other configurations are the same as those of the first embodiment, the same configurations are denoted by the same reference numerals, and descriptions of structures, operations, and effects are omitted.
[0026]
[Other Embodiments]
The present invention is not limited to the embodiment described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.
(1) In the above embodiment, the protrusions are formed only on the outer periphery of the cylindrical lead-out part. However, according to the present invention, the protrusions may be formed only on the inner periphery of the cylindrical lead-out part. It may be formed on both the outer periphery and inner periphery of the part, may be formed only on the inner periphery of the cap, or may be formed on the inner periphery of the cap and the inner periphery of the cylindrical lead-out part. It may be formed on the outer periphery of the cylindrical lead-out portion, or may be formed on all of the inner periphery and outer periphery of the cylindrical lead-out portion and the inner periphery of the cap.
[0027]
(2) In the above embodiment, the protrusions are formed only at one position in the axial direction of the cylindrical lead-out portion. However, according to the present invention, the protrusions may be formed at a plurality of positions in the axial direction.
(3) Although the case where the electronic device is a liquid leakage sensor has been described in the above embodiment, the present invention can also be applied to other electronic devices other than the liquid leakage sensor.
[Brief description of the drawings]
FIG. 1 is a horizontal cross-sectional view of Embodiment 1. FIG. 2 is a horizontal cross-sectional view showing an exploded state. FIG. 3 is a horizontal cross-sectional view showing a state in the middle of assembly. Fig. 6 is a partially enlarged horizontal sectional view showing a cylindrical lead-out portion. Fig. 7 is an enlarged horizontal sectional view of a cap. Fig. 8 is a portion showing a state in which the cap is externally fitted to the cylindrical lead-out portion. Enlarged horizontal cross-sectional view [FIG. 9] (a) Cross-sectional view showing a state before inserting the wedge member in the cylindrical lead-out portion (b) Cross-sectional view showing a state in which the wedge member is inserted in the cylindrical lead-out portion [FIG. 10. Vertical sectional view of Embodiment 2 [Explanation of symbols]
A ... Leak sensor (electronic equipment)
DESCRIPTION OF SYMBOLS 10 ... Case 13 ... Cable 13A ... Protection tube 13B ... Conductor 17 ... Cylindrical derivation | leading-out part 23 ... Projection 23B ... Tapered surface 25 ... Cap 32 ... Wedge member 34 ... Concave part 35 ... Convex part B ... Liquid leak sensor (electronic device)
40 ... Cylindrical outlet 42 ... Cap

Claims (4)

In the outer surface of the case, a cylindrical lead-out portion is provided to project the cable from the case to the outside, and a cylindrical cap is externally fitted to the cylindrical lead-out portion.
The case and the cylindrical lead-out part are integrally formed of the same material,
The cylindrical lead-out portion has a thin portion thinner than the thickness of the case over the entire circumference, and an annular protrusion is formed over the entire circumference on the peripheral surface of the thin portion,
The cap is configured to be more rigid than the cylindrical lead-out part,
In the annular region along the ridge, the tubular lead-out portion is compressed so as to bite into the outer periphery of the cable by being pushed in the radial direction on the inner circumference of the cap fitted on the tubular lead-out portion. An electronic device characterized in that it is configured to deform in diameter.   The electronic device according to claim 1, wherein the protrusion is formed on an outer periphery of the cylindrical lead-out portion, and a taper surface is formed on the protrusion.   The cable has a configuration in which a plurality of conductors are inserted into a protective tube and the protective tube is passed through the cylindrical lead-out portion, and the protective tube is disposed in the cylindrical shape in the protective tube. The electronic device according to claim 1, wherein a wedge member that presses the inner periphery of the lead-out portion is inserted.   4. The electronic apparatus according to claim 3, wherein a circumferential concavo-convex portion that bites into an inner periphery of the protective tube is formed on an outer periphery of the wedge member.

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