Water-stopping structure

Abstract

To provide a water stop structure which can inhibit a heat-shrinkable tube from being displaced from a desired position with a simple structure.SOLUTION: A water stop structure 1 includes: a housing 3; a cable 4 having an electric wire 41 disposed in the housing 3 and a sheath 42 which is disposed spaced apart from the housing 3 at the outside of the housing 3; and a heat-shrinkable tube 5 which covers a part of the housing 3 and an end of the cable 4 exposed from the housing 3. The heat-shrinkable tube 5 enters a space between the housing 3 and the sheath 42.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a water-stop structure. [Background Art]

[0002] Patent Document 1 discloses a water-stop structure using a heat-shrinkable tube. In the water-stop structure described in Patent Document 1, in a multi-core cable, a gap between a sheath and an electric wire exposed from the sheath is covered with a heat-shrinkable tube to achieve water stopping. In Patent Document 1, the multi-core cable is housed in a lower case and an upper case. The lower case is provided with a stopper for preventing the heat-shrinkable tube from falling off the sheath. [Prior Art Document] [Patent Document]

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2020-031464 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] However, in the invention described in Patent Document 1, a stopper is provided to suppress movement of the heat-shrinkable tube from a predetermined position, so the structure tends to be complicated, and there is room for improvement.

[0005] The present invention has been made in view of the foregoing circumstances, and an object of the present invention is to provide a water-stop structure that can suppress displacement of a heat-shrinkable tube from a desired position with a simple configuration. [Means for Solving the Problem]

[0006] To achieve the above objective, the present invention provides a watertight structure comprising a housing, a cable having an electric wire disposed within the housing and a sheath disposed outside the housing at a distance from the housing, and a heat-shrinkable tube covering a part of the housing and the end of the cable exposed from the housing, wherein the heat-shrinkable tube is inserted between the housing and the sheath. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a water-stopping structure that can prevent heat-shrinkable tubing from shifting from a desired position with a simple configuration. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional side view of a part of the sensor device in the first embodiment. [Figure 2] This is an enlarged perspective view of the area around the heat shrink tubing of the sensor device in the first embodiment. [Figure 3] This is a magnified view of the area around the heat shrink tubing in Figure 1. [Figure 4] This is a cross-sectional side view of a part of the sensor device in the second embodiment. [Modes for carrying out the invention]

[0009] [First Embodiment] A first embodiment of the present invention will be described with reference to Figures 1 to 3. The embodiments described below are presented as preferred specific examples for carrying out the present invention, and while some parts specifically illustrate various technically preferable technical matters, the technical scope of the present invention is not limited to these specific embodiments.

[0010] This embodiment is a sensor device 10 having a water-stopping structure 1. Figure 1 is a cross-sectional side view of a part of the sensor device 10 in this embodiment. Figure 2 is an enlarged perspective view of the area around the heat-shrinkable tube 5 of the sensor device 10. Figure 3 is an enlarged view of the area around the heat-shrinkable tube 5 in Figure 1.

[0011] The sensor device 10 is used to measure a predetermined physical quantity and is mounted, for example, on a vehicle. Since the components mounted on the vehicle may be surrounded by oil and moisture, the water-sealing structure 1 of this embodiment is suitable for use. Note that the water-sealing structure 1 can also be applied to components other than the sensor device 10.

[0012] As shown in Figure 1, the sensor device 10 comprises a detection unit 2 that converts a physical quantity into an electrical signal, a housing 3 that houses the detection unit 2, a cable 4 that is electrically connected to the detection unit 2 and extends out of the housing 3, and a heat-shrinkable tube 5 that covers the boundary between the housing 3 and the cable 4 as seen from the outside. Hereafter, the longitudinal direction of the cable 4 (i.e., the axial direction of the cable 4) will be referred to as the axial direction X, one side of the axial direction X from which the cable 4 is drawn out of the housing 3 (right side in Figure 1) will be referred to as the axial base end side, and the opposite side (left side in Figure 1) will be referred to as the axial tip side.

[0013] The detection unit 2 consists of, for example, an element capable of detecting a predetermined physical quantity. As an example, the detection unit 2 can be a magnetic detection element such as a Hall IC that detects magnetism. The detection unit 2 transmits the output result to an external control device or the like via the cable 4.

[0014] The housing 3 accommodates the detection unit 2 and the wiring path for outputting the signal from the detection unit 2. The housing 3 can be made of, for example, an electrically insulating resin. The housing 3 may be made of a single component or a combination of multiple components.

[0015] The housing 3 has a main body 31 that houses the detection unit 2 and an extension 32 that extends to one side from the housing. A wire housing space 320 for housing multiple wires 41 of the cable 4 is formed within the extension 32. As shown in Figures 2 and 3, the extension 32 has an annular small-diameter portion 321 formed at the axial base end and a large-diameter portion 322 that is formed adjacent to the small-diameter portion 321 and has a larger outer diameter than the small-diameter portion 321. The cable 4 is drawn out from the small-diameter portion 321 towards the axial base end.

[0016] The cable 4 comprises a plurality of electric wires 41 connected to the detection unit 2, and a sheath 42 that covers the plurality of electric wires 41 collectively and is positioned further away from the base end than the housing 3. Each of the plurality of electric wires 41 consists of an insulated electric wire having a conductive core and an electrically insulating covering portion that covers the core. The plurality of electric wires 41 are twisted together to form a stranded wire. The plurality of electric wires 41 exposed between the housing 3 and the sheath 42 are also twisted together.

[0017] The sheath 42 is formed from an electrically insulating resin or the like in a cylindrical shape. As shown in Figure 3, the sheath 42 is positioned at the axial base end of the housing 3, that is, at a position away from the axial base end face 321a of the small diameter portion 321. In this embodiment, the axial tip end face 421 of the sheath 42 and the end face 321a of the small diameter portion 321 face each other in the axial direction X. The axial distance D between the end face 421 of the sheath 42 and the end face 321a of the small diameter portion 321 in the axial direction X is greater than twice the maximum thickness T1 of the heat shrink tube 5. The thickness of the heat shrink tube 5 increases with the amount of heat shrinkage, and the maximum thickness T1 of the heat shrink tube 5 is the thickness of the smallest diameter portion in the third portion 53. In Figure 3 and other figures, for convenience, the heat shrink tube 5 is shown as having a constant thickness, but as mentioned above, the thickness of the heat shrink tube 5 can vary depending on the location. In this embodiment, the spacing D is smaller than the maximum width W of the heat shrink tube 5 in the direction perpendicular to the axial direction X (i.e., the outer diameter of the first portion 51 described later), and also smaller than the outer diameter OD1 of the sheath 42. In this embodiment, the outer diameter OD1 of the sheath 42 is smaller than the outer diameter OD2 of the small diameter portion 321. Furthermore, the heat shrink tube 5 is provided between the housing 3 and the sheath 42 to prevent foreign matter such as oil and moisture from entering.

[0018] The heat-shrinkable tube 5 is configured to shrink toward at least the inner peripheral side of the heat-shrinkable tube 5 when the temperature reaches or exceeds a predetermined temperature. The heat-shrinkable tube 5 collectively covers the axial proximal end of the housing 3, the axial distal end of the sheath 42, and the plurality of electric wires 41 exposed between the housing 3 and the sheath 42, and has a portion that is inserted between the end face 421 of the sheath 42 and the end face 321a of the small-diameter portion 321. Hereinafter, in the heat-shrinkable tube 5, the portion disposed on the outer peripheral side of the housing 3 is referred to as a first portion 51, the portion disposed on the outer peripheral side of the sheath 42 is referred to as a second portion 52, and the portion between the first portion 51 and the second portion 52 that is inserted between the sheath 42 and the housing 3 is referred to as a third portion 53. A hot melt, which is an adhesive that melts at a temperature equal to or higher than a predetermined temperature and re-hardens when the temperature becomes lower than the predetermined temperature, may be provided on the inner peripheral portion of the heat-shrinkable tube 5.

[0019] The housing covered surface 30, which is a portion of the surface of the housing 3 covered by the first portion 51 of the heat-shrinkable tube 5, includes the end face and outer peripheral surface of the small-diameter portion 321, and the axial proximal end face and a part of the outer peripheral surface of the large-diameter portion 322. The housing covered surface 30 is formed such that the diameter thereof decreases closer to the sheath 42. In the present embodiment, the housing covered surface 30 is formed in a stepped shape by the small-diameter portion 321 and the large-diameter portion 322. Accordingly, the first portion 51 of the heat-shrinkable tube 5 is also formed in a stepped shape similar to the shape of the housing covered surface 30. Note that, as long as the housing covered surface 30 is formed such that the diameter thereof decreases closer to the sheath 42, it may be formed not in a stepped shape but, for example, in a tapered shape or the like. The length L1 of the first portion 51 in the axial direction X is longer than the maximum thickness T2 of the portion of the housing 3 covered by the first portion 51 of the heat-shrinkable tube 5 (that is, the thickness of the large-diameter portion 322).

[0020] A sheath-covered surface 422, which is a portion covered by the second portion 52 of the heat-shrinkable tube 5 on the surface of the sheath 42, is formed in a cylindrical shape parallel to the axial direction X. The length L2 of the second portion 52 in the axial direction X is longer than the thickness T3 of the sheath 42. In the present embodiment, the length L2 of the second portion 52 in the axial direction X is longer than the length L1 of the first portion 51 in the axial direction X.

[0021] Here, the maximum thickness T2 of the portion of the housing 3 covered by the first portion 51 of the heat-shrinkable tube 5 is larger than the thickness T3 of the sheath 42. Further, the maximum circumferential length of the housing-covered surface 30 is longer than the circumferential length of the surface of the sheath 42. Note that the maximum circumferential length of the housing-covered surface 30 refers to the maximum value among the circumferential lengths of the housing-covered surface 30 at each position in the axial direction X, and in the present embodiment, it is the circumferential length of the outer peripheral surface of the large-diameter portion 322. Since the maximum circumferential length of the housing-covered surface 30 is longer than the circumferential length of the surface of the sheath 42, the heat-shrinkable tube 5 is formed such that the first portion 51 spreads more toward the outer peripheral side than the second portion 52. In such a case, when the heat-shrinkable tube 5 shrinks or under other circumstances, a force that tends to cause the heat-shrinkable tube 5 to slip off from the first portion 51 side that spreads more toward the outer peripheral side toward the second portion 52 side having a smaller diameter (i.e., toward the proximal end side in the axial direction) is easily generated. Therefore, in the present embodiment, the heat-shrinkable tube 5 is provided with a third portion 53 that enters between the sheath 42 and the housing 3. This allows the heat-shrinkable tube 5 to be caught by the third portion 53, thereby suppressing displacement of the heat-shrinkable tube 5 from a desired position, for example before and after thermal shrinkage of the heat-shrinkable tube 5.

[0022] In the present embodiment, the third portion 53 of the heat-shrinkable tube 5 extends to the inner peripheral side beyond the inner peripheral surface 42a of the sheath 42. That is, the innermost peripheral portion of the third portion 53 is located at a position closer to the inner peripheral side than the inner peripheral surface 42a of the sheath 42. The third portion 53 may be in contact with the plurality of electric wires 41 exposed between the sheath 42 and the housing 3. The outer peripheral surface of the third portion 53 has a portion located closer to the inner peripheral side than the radial positions of the outer peripheral surface of the sheath 42 and the outer peripheral surface of the small-diameter portion 321. Note that in FIG. 3, the radial positions of the outer peripheral surface of the sheath 42 and the outer peripheral surface of the small-diameter portion 321 are indicated by alternate long and short dash lines.

[0023] The axial length L3 (i.e., spacing D) of the third portion 53 is smaller than the axial length L1 of the first portion 51 and the axial length L2 of the second portion 52. Also, the axial length L3 of the third portion 53 is greater than twice the maximum thickness T1 of the heat shrink tube 5. Furthermore, the axial length L3 of the third portion 53 is preferably smaller than the maximum width W of the heat shrink tube 5 in the direction perpendicular to the axial direction X, i.e., the outer diameter of the first portion 51, and even more preferably smaller than the outer diameter OD1 of the sheath 42.

[0024] The heat shrink tubing 5 is formed, for example, by the following method. First, the heat shrink tubing 5, which has an outer diameter larger than the housing covering surface 30 and the sheath covering surface 422, is placed around the housing covering surface 30 and the sheath covering surface 422 before heat shrinking. Next, the heat shrink tubing 5 is heated and shrunk to make it adhere to the housing covering surface 30 and the sheath covering surface 422, either directly or via hot melt if hot melt is available. At this time, the third portion 53 is reduced in diameter so that it fits between the housing 3 and the sheath 42. The heat shrink tubing 5 is provided in this manner.

[0025] (Operation and effects of the first embodiment) In this embodiment of the water-sealing structure 1, the heat-shrinkable tube 5 has a third portion 53 that fits between the housing 3 and the sheath 42. Therefore, the third portion 53 that fits between the housing 3 and the sheath 42 prevents the heat-shrinkable tube 5 from shifting axially X from the desired position when it is heat-shrinkable. Thus, according to this embodiment, it is possible to prevent the heat-shrinkable tube 5 from shifting from the desired position with a simple configuration.

[0026] Furthermore, the axial distance D between the housing 3 and the sheath 42 is greater than twice the maximum thickness T1 of the heat shrink tubing 5. Therefore, the heat shrink tubing 5 can easily fit between the housing 3 and the sheath 42, and displacement of the heat shrink tubing 5 from the desired position is further suppressed.

[0027] Furthermore, the axial distance D between the housing 3 and the sheath 42 is smaller than the maximum width W of the heat shrink tube 5 in the direction perpendicular to the axial direction X (i.e., the outer diameter of the first portion 51). If the axial distance D between the housing 3 and the sheath 42 is excessively large, there is a risk that at least one of the ends of the heat shrink tube 5 may fall between the housing 3 and the sheath 42, but in this embodiment, it is possible to suppress the occurrence of such a situation.

[0028] Furthermore, the housing covering surface 30, which is covered with heat shrink tubing 5 on the surface of the housing 3, is formed to be smaller in diameter towards the side closer to the sheath 42. This makes it easier for the third portion 53 to fit between the housing 3 and the sheath 42. That is, for example, if the diameter of the end of the first portion 51 of the heat shrink tubing 5 on the side of the third portion 53 is large, the diameter will change abruptly at the boundary between the first portion 51 and the third portion 53. However, it is difficult to realize such a configuration, and it is conceivable that the third portion 53 will not fit properly between the housing 3 and the sheath 42. Therefore, by forming the housing covering surface 30 to be smaller in diameter towards the side closer to the sheath 42, the diameter of the portion of the first portion 51 on the side of the third portion 53 can be reduced. This prevents abrupt changes in the diameter between the end of the first portion 51 on the side of the third portion 53 and the third portion 53, making it easier for the third portion 53 to fit between the housing 3 and the sheath 42.

[0029] Furthermore, the housing covering surface 30 is formed in a stepped shape. Therefore, the contact area between the housing covering surface 30 and the heat shrink tube 5 can be increased, and the heat shrink tube 5 can be prevented from coming off the housing 3.

[0030] Furthermore, the heat shrink tubing 5 has a portion that extends further inward than the inner circumferential surface 42a of the sheath 42. Therefore, the heat shrink tubing 5 is more likely to catch on the housing 3 and the sheath 42 at the third portion 53, making it easier to suppress the heat shrink tubing 5 from shifting axially X from the desired position.

[0031] Furthermore, the axial length L1 of the first portion 51 of the heat shrink tube 5 is longer than the maximum thickness T2 of the portion of the housing 3 covered by the heat shrink tube 5, and the axial length L2 of the second portion 52 of the heat shrink tube 5 is longer than the thickness T3 of the sheath 42. Therefore, the contact area between the heat shrink tube 5 and the housing 3 and sheath 42 can be increased, making it easier to suppress the heat shrink tube 5 from shifting axially X from the desired position. In addition, it is possible to suppress at least one of the ends of the heat shrink tube 5 from falling between the housing 3 and the sheath 42.

[0032] Furthermore, the axial length L3 of the third portion 53 of the heat shrink tube 5 is smaller than the axial length L1 of the first portion 51 of the heat shrink tube 5 and the axial length L2 of the second portion 52 of the heat shrink tube 5. Therefore, it is possible to prevent at least one of the ends of the heat shrink tube 5 from falling between the housing 3 and the sheath 42.

[0033] As described above, this embodiment provides a watertight structure 1 that can suppress the detachment of the heat shrink tubing with a simple configuration.

[0034] [Second Embodiment] Figure 4 is a cross-sectional side view of a part of the sensor device 10 in this embodiment.

[0035] This embodiment is a modified version of the first embodiment in which the configuration of the housing 3 is changed. In this embodiment, the housing 3 has an inner housing 33 and an outer housing 34 that covers the inner housing 33. The outer housing 34 is made of, for example, molded resin that covers the inner housing 33. The inner housing 33 has a projection 331 that protrudes from the outer housing 34 toward the axial base end. Due to the projection 331 and the axial base end of the outer housing 34, the surface of the axial base end of the housing 3 is formed in a stepped shape that decreases in diameter toward the axial base end. The first portion 51 of the heat shrink tube 5 covers the projection 331 and the axial base end of the outer housing 34. For example, the inner housing 33 can also be constructed by combining multiple members.

[0036] The other configurations of this embodiment are the same as those of the first embodiment. In addition, among the reference numerals used in the second embodiment and subsequent embodiments, those that are the same as those used in the previously described embodiments represent the same components, etc., as those in the previously described embodiments, unless otherwise specified.

[0037] (Operation and effects of the second embodiment) In this embodiment, the housing covering surface 30 is formed in a stepped shape by the protruding portion 331 of the inner housing 33 and the outer housing 34. Therefore, the housing covering surface 30 can be easily formed in a stepped shape. Furthermore, it has the same functions and effects as the first embodiment.

[0038] (Summary of the embodiments) Next, the technical concept understood from the embodiments described above will be described using the reference numerals and other symbols from the embodiments. However, the reference numerals and other symbols in the following description are not limited to the components in the claims that are specifically shown in the embodiments.

[0039] [1] A watertight structure (1) comprising a housing (3), a cable (4) having an electric wire (41) disposed inside the housing (3) and a sheath (42) disposed outside the housing (3) at a position away from the housing (3), and a heat shrink tube (5) covering a part of the housing (3) and the end of the cable (4) exposed from the housing (3), wherein the heat shrink tube (5) is inserted between the housing (3) and the sheath (42).

[0040] [2] The watertight structure (1) according to [1], wherein the distance (D) between the housing (3) and the sheath (42) in the longitudinal direction (X) of the cable (4) is greater than twice the maximum thickness (T1) of the heat shrink tube (5).

[0041] [3] The watertight structure (1) according to [1] or [2], wherein the distance (D) between the housing (3) and the sheath (42) in the longitudinal direction (X) of the cable (4) is smaller than the maximum width (W) of the heat shrink tube (5) in the direction perpendicular to the longitudinal direction (X).

[0042] [4] The housing covering surface (30) on the surface of the housing (3) that is covered by the heat shrinkable tube (5) is formed to be smaller in diameter towards the side closer to the sheath (42), the water-stopping structure (1) according to any one of [1] to [3].

[0043] [5] The housing covering surface (30) is formed in a stepped shape, the water-stopping structure (1) according to [4].

[0044] [6] The housing (3) comprises an inner housing (33) and an outer housing (34) covering the inner housing (33), the inner housing (33) having a projection (331) that protrudes from the outer housing (34) toward the sheath (42), and the housing covering surface (30) is formed in a stepped shape by the projection (331) and the outer housing (34), the water-stopping structure (1) according to [5].

[0045] [7] The watertight structure (1) according to any one of [1] to [6], wherein the heat shrinkable tube (5) has a portion (53) that extends further inward than the inner surface (42a) of the sheath (42).

[0046] [8] The watertight structure (1) according to any one of [1] to [7], wherein the length (L1) in the longitudinal direction (X) of the portion (51) of the heat shrink tube (5) that covers the housing (3) is longer than the maximum thickness (T2) of the portion of the housing (3) that is covered by the heat shrink tube (5), and the length (L2) in the longitudinal direction (X) of the portion (52) of the heat shrink tube (5) that covers the sheath (42) is longer than the thickness (T3) of the sheath (42).

[0047] [9] The length (L3) in the longitudinal direction (X) of the cable (4) in the portion (53) between the housing (3) and the sheath (42) of the heat shrink tube (5) is smaller than the length (L1) in the longitudinal direction (X) of the portion (51) covering the housing (3) of the heat shrink tube (5), and the length (L2) in the longitudinal direction (X) of the portion (52) covering the sheath (42) of the heat shrink tube (5), according to any one of [1] to [8].

[0048] (Note) Although embodiments of the present invention have been described above, the embodiments described herein do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention. Moreover, the present invention can be implemented with appropriate modifications without departing from its spirit. [Explanation of symbols]

[0049] 1…Waterproof structure 3… Housing 30…Housing coating surface 33…Inner Housing 331...Protruding part 34…Outer Housing 4… Cable 41...Electric wire 42...Sheath 42a... Inner surface of the sheath 5… Heat shrink tubing 51...Part 1 52…Second part 53…3rd part T1...Maximum thickness of heat shrink tubing T2…Maximum thickness of the portion of the housing covered with heat shrink tubing. T3...Sheath thickness X...Longest direction of the cable W...Maximum width of heat shrink tubing

Claims

1. Housing and A plurality of electric wires arranged inside the housing, and a cable having a sheath that covers the plurality of electric wires together, located outside the housing at a distance from the housing. The housing comprises a heat-shrinkable tube that covers a portion of the housing and the end of the cable exposed from the housing, The heat shrink tubing has a first portion that covers a part of the housing, a second portion that covers the sheath, and a third portion that is between the first portion and the second portion and is inserted between the housing and the sheath. The third portion is in direct contact with the electric wire that is exposed between the sheath and the housing. No hot melt adhesive is provided on the inner circumference of the heat shrinkable tube. Watertight structure.

2. The distance between the housing and the sheath in the longitudinal direction of the cable is greater than twice the maximum thickness of the heat shrink tubing. The water-stopping structure according to claim 1.

3. The distance between the housing and the sheath in the longitudinal direction of the cable is smaller than the maximum width of the heat shrink tubing in a direction perpendicular to the longitudinal direction. The water-stopping structure according to claim 1 or 2.

4. The housing covering surface covered by the heat shrink tubing on the surface of the housing is formed to be smaller in diameter towards the side closer to the sheath. The water-stopping structure according to any one of claims 1 to 3.

5. The housing covering surface is formed in a stepped shape, The portion of the heat shrinkable tube that covers the housing surface is formed in a stepped shape along the housing surface. The water-stopping structure according to claim 4.

6. The housing comprises an inner housing and an outer housing that covers the inner housing. The inner housing has a protruding portion that extends from the outer housing toward the sheath side, The protruding portion and the outer housing form a stepped surface on the housing covering. The water-stopping structure according to claim 5.

7. The longitudinal length of the portion of the heat shrink tubing that covers the housing is longer than the maximum thickness of the portion of the housing covered by the heat shrink tubing, and the longitudinal length of the portion of the heat shrink tubing that covers the sheath is longer than the thickness of the sheath. The water-stopping structure according to any one of claims 1 to 6.

8. The longitudinal length of the cable in the portion of the heat shrink tubing between the housing and the sheath is smaller than the longitudinal length of the portion of the heat shrink tubing covering the housing and the longitudinal length of the portion of the heat shrink tubing covering the sheath. The water-stopping structure according to any one of claims 1 to 7.

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