Sealing member and sealing structure using the same

Abstract

To provide a sealing member capable of being easily assembled and obtaining sufficient waterproof and dustproof effects, and a sealing structure using the sealing member.SOLUTION: A cover 15 has a first opening and a second opening that is continuous with the first opening in a part of the periphery of the first opening, and covers a part of a structure. A sealing member 17 comprises an annular first bushing 17a fitted between the first opening and a cylindrical body 16, and a second bushing 17b connected to the first bushing and fitted into the second opening.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a sealing member that is applied to, for example, a torque sensor and that prevents moisture and dust from entering the torque sensor, and a sealing structure that uses the sealing member. [Background technology]

[0002] For example, a torque sensor is a precision device that has a signal processing circuit inside. Therefore, it is necessary to make the sensor waterproof and dustproof to protect the signal processing circuit from moisture and dust. Generally, a torque sensor is provided with a packing that protects the sensor unit from moisture and dust (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-060346 Summary of the Invention [Problem to be solved by the invention]

[0004] The torque sensor has a holder that holds a printed circuit board on which a signal processing circuit is mounted, and a cover that covers the printed circuit board. A bushing that holds a cable connected to the signal processing circuit is attached to the cover. Gaps exist between the holder and the cover, and between the cover and the bushing. To seal these gaps, multiple waterproof and dustproof sealing members are provided. Commercially available O-rings, annular rubber members, and waterproof bushings can be used as these sealing members.

[0005] However, commercially available sealing members are not suitable for miniaturizing torque sensors. Furthermore, because multiple sealing members are required to seal multiple gaps, assembly is cumbersome. Furthermore, when multiple sealing members are placed close to each other, they interfere with each other, creating gaps, preventing sufficient waterproofing and dustproofing, and reducing reliability.

[0006] The embodiments of the present invention provide a highly reliable sealing member that is easy to assemble and can provide sufficient waterproof and dustproof effects, and a sealing structure using the same. [Means for solving the problem]

[0008] The sealing structure of this embodiment includes a cover that has a first opening and a second opening that is continuous with the first opening at a portion around the first opening and covers a portion of a structure, and a sealing member that includes a cylindrical body that is disposed inside the first opening, a first annular bushing that is fitted between the first opening and the cylindrical body, and a second bushing that is connected to the first bushing and fitted in the second opening. The first bush and the second bush have grooves that are continuous around their peripheries and fit into the edges of the first opening and the second opening of the cover, and a third bush is further provided in the second bush to hold a cable connected to a printed circuit board arranged inside the cover. To be equipped. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a plan view showing an example of a torque sensor to which a sealing member and a sealing structure according to an embodiment of the present invention are applied. [Figure 2] FIG. 2 is a perspective view of the torque sensor shown in FIG. 1. [Figure 3] FIG. 2 is a plan view showing the torque sensor shown in FIG. 1 with a part thereof removed. [Figure 4] FIG. 2 is a perspective view showing an example of a sealing member according to the embodiment. [Figure 5] 2 is a cross-sectional view taken along line VV in FIG. 1, showing an example of a sealing structure according to the present embodiment. [Figure 6] FIG. 10 is a cross-sectional view showing only a portion of a first modified example of the sealing member according to the embodiment. [Figure 7] FIG. 10 is a cross-sectional view showing only a portion of a second modified example of the sealing member according to the embodiment. [Figure 8] FIG. 10 is a cross-sectional view showing only a portion of a third modified example of the sealing member according to the embodiment. [Figure 9] FIG. 10 is a cross-sectional view showing only a part of a fourth modified example of the sealing member according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the drawings, in which the same parts are designated by the same reference numerals.

[0011] 1 and 2 show an example of a torque sensor 10 to which this embodiment is applied. The configuration of the torque sensor 10 is not limited to this, and the present embodiment can be applied to torque sensors of various configurations. This embodiment is not limited to torque sensors, and can also be applied to force sensors using strain gauges, etc.

[0012] 1 and 2, the torque sensor 10 includes a first structure 11, a second structure 12, a plurality of third structures 13, a plurality of waterproof and dustproof caps 14, a cover 15, a cylindrical body 16, a sealing member 17, and a cable 18.

[0013] The first structure 11 and the second structure 12 are formed in an annular shape, the diameter of the second structure 12 is smaller than the diameter of the first structure 11, and the second structure 12 is arranged concentrically with the first structure 11. The first structure 11 and the second structure 12 are connected by a plurality of third structures 13 as beam portions arranged radially.

[0014] The first structure 11 is connected to, for example, a measurement object, the second structure 12 is connected to another structure (not shown), and multiple third structures 13 transmit torque from the first structure 11 to the second structure 12. Conversely, the second structure 12 may be connected to the measurement object, the first structure 11 may be connected to another structure (not shown), and torque may be transmitted from the second structure 12 to the first structure 11 via multiple third structures 13.

[0015] The first structure 11, the second structure 12, and the plurality of third structures 13 are made of metal, for example, stainless steel, but materials other than metal can also be used as long as they have sufficient mechanical strength to withstand the applied torque.

[0016] A plurality of strain sensors, which will be described later, are provided between the first structure 11 and the second structure 12, and these strain sensors are covered by a cap .

[0017] The cover 15 is attached to the second structure 12. The cover 15 has a first opening and a second opening, which will be described later, and the cylindrical body 16 is disposed in the first opening. Furthermore, a sealing member 17 is provided between the first opening and the cylindrical body 16 and at the second opening. The cable 18 is held by the sealing member 17.

[0018] FIG. 3 shows a state in which the sealing member 17 and one cap 14 have been removed, exposing the strain sensor 20. In this embodiment, four strain sensors 20 are arranged. The number of strain sensors 20 is four, but is not limited to this. Each strain sensor 20 is arranged between the first structure 11 and the second structure 12 at a position different from the third structure 13. Each strain sensor 20 includes a metallic strain element 21 and a plurality of strain gauges 22. One end of the strain element 21 is fixed to the first structure 11, and the other end of the strain element 21 is fixed to the second structure 12. Each strain sensor 20 is covered with a cap 14, providing a dustproof and waterproof structure.

[0019] As shown in Figures 1 to 3, the cover 15 is provided on the surface of the second structure 12. As shown in Figure 5, the second structure 12 has a hollow portion 12a, and an annular printed circuit board 23 is provided in the hollow portion 12a. That is, the printed circuit board 23 has an opening 23a that communicates with the hollow portion 12a. The printed circuit board 23 is fixed to the second structure 12, and the surface of the printed circuit board 23 is covered with the cover 15. The printed circuit board 23 is provided with a signal processing circuit 24 that supplies power to the multiple strain sensors 20, processes electrical signals supplied from the multiple strain sensors 20, and generates a detection signal corresponding to torque.

[0020] One end of the cable 18 is electrically connected to a signal processing circuit 24 provided on the printed circuit board 23, and the other end is disposed inside the cylindrical body 16. The signal processing circuit 24 receives power from the cable 18 and transmits a detection signal via the cable 18.

[0021] 3, the cover 15 has a first opening 15a and a second opening 15b on its surface. The first opening 15a communicates with the hollow portion 12a of the second structure 12 and the opening 23a of the printed circuit board 23. The second opening 15b is formed continuous with a part of the first opening 15a.

[0022] The cylindrical body 16 is disposed inside the first opening 15a of the cover 15 and the opening 23a of the printed circuit board 23. As shown in FIG. 5 , the cylindrical body 16 is formed integrally with the holder 16a at the center of the holder 16a. That is, one end of the cylindrical body 16 is provided on the holder 16a. The holder 16a is disposed on the back side of the printed circuit board 23 and fixed to the second structure 12. The other end of the cylindrical body 16 passes through the first opening 15a of the cover 15 and the opening 23a of the printed circuit board 23, and protrudes slightly from the first opening 15a of the cover 15.

[0023] 3, a gap G is provided between the cylindrical body 16 and the first opening 15a of the cover 15. As shown in FIGS. 1 and 2, a waterproof and dustproof sealing member 17 is disposed to close the gap G and the second opening 15b.

[0024] FIG. 4 shows the sealing member 17. The sealing member 17 is formed of, for example, silicone rubber or an elastic resin material, but other materials can also be used. The sealing member 17 has an annular first bushing 17a and a second bushing 17b, which are integrally connected to each other. The shape of the first bushing 17a corresponds to the gap G. The inner diameter of the first bushing 17a is smaller than the outer diameter of the cylindrical body 16, allowing it to fit tightly against the side surface of the cylindrical body 16. The shape of the second bushing 17b corresponds to the shape of the second opening 15b and has an opening through which the cable 18 is inserted. A cable bushing 17c that holds the cable 18 is integrally formed on the second bushing 17b.

[0025] Grooves 17d that fit into the edges of the first opening 15a and the second opening 15b are continuously provided around the first bushing 17a and the second bushing 17b. The diameter of the groove 17d provided in the first bushing 17a is slightly larger than the diameter of the first opening 15a, and the shape of the groove 17d provided in the second bushing 17b is slightly larger than the shape of the second opening 15b. Therefore, the first bushing 17a can be tightly fitted to the first opening 15a, and the second bushing 17b can be tightly fitted to the second opening 15b.

[0026] 5, first bushing 17a of sealing member 17 is fitted into gap G between first opening 15a of cover 15 and cylindrical body 16, and second bushing 17b is fitted into second opening 15b. In this state, groove 17d of first bushing 17a is pressed against the periphery of first opening 15a, and groove 17d of second bushing 17b is pressed against the periphery of second opening 15b.

[0027] The portion of first bushing 17a other than groove 17d overlaps the front and back surfaces of cover 15 around first opening 15a, and the portion of second bushing 17b other than groove 17d also overlaps the front and back surfaces of cover 15 around second opening 15b. Therefore, gap G between first opening 15a and cylindrical body 16 of cover 15 and second opening 15b are integrally closed by sealing member 17.

[0028] In the assembly work, for example, first, one end of the cable 18 is connected to the printed circuit board 23, and the printed circuit board 23 and holder 16a are fixed inside the second structure 12. After this, the first bushing 17a and the second bushing 17b of the sealing member 17 are attached to the first opening 15a and the second opening 15b of the cover 15, and the cable 18 is inserted into the cable bushing 17c, and the cover 15 is fixed to the second structure 12. At this time, the cylindrical body 16 is press-fitted inside the first bushing 17a.

[0029] The assembly method is not limited to this, and for example, first, the printed circuit board 23, the holder 16a, and the cover 15 may be fixed to the second structure 12, and finally the first bush 17a of the sealing member 17 may be pressed into between the first opening 15a and the cylindrical body 16, and the second bush 17b may be pressed into the second opening 15b.

[0030] (Effects of the embodiment) According to the above embodiment, the sealing member 17 has a first bushing 17a that is fitted into the gap G between the first opening 15a of the cover 15 and the cylindrical body 16, and a second bushing 17b that is fitted into the second opening 15b, and the first bushing 17a and the second bushing 17b are integrally connected. This makes it possible to reliably close the gap G between the first opening 15a of the cover 15 and the cylindrical body 16, and the second opening 15b, thereby improving the reliability of the torque sensor.

[0031] Moreover, because first bushing 17a and second bushing 17b are integrally connected, sealing member 17 can be easily attached to gap G and second opening 15b, thereby reducing the number of assembly steps.

[0032] Furthermore, grooves 17d are provided around the first bushing 17a and the second bushing 17b, and these grooves 17d fit into the edges of the first opening 15a and the second opening 15b of the cover 15. Therefore, the parts of the first bushing 17a and the second bushing 17b other than the grooves 17d are arranged on the front and back surfaces of the cover 15, thereby improving the waterproof and dustproof effects.

[0033] (First Modification) FIG. 6 shows a first modified example of this embodiment, and is an enlarged view of the portion indicated by A in FIG. In the first modified example, an inclined portion 17e is provided on the inner surface of the first bushing 17a in a portion located on the rear surface side of the cover 15. The inclined portion 17e is inclined so as to move away from the inner surface of the first bushing 17a as it approaches the rear surface of the first bushing 17a.

[0034] Specifically, the inner diameter D1 of the first bush 17a is smaller than the outer diameter D2 of the cylindrical body 16 (D1 < D2), and the diameter D3 of the inclined portion 17e on the bottom surface of the first bush 17a is larger than the outer diameter D2 of the cylindrical body 16 (D2 < D3). Therefore, when the cylindrical body 16 is inserted into the first bush 17a, the cylindrical body 16 is guided into the first bush 17a by the inclined portion 17e.

[0035] According to the first modification example, the first bush 17a has an inclined portion 17e on its inner surface. Therefore, when the cylindrical body 16 is inserted into the first bush 17a, the cylindrical body 16 can be inserted along the inclined portion 17e. Thus, even when the inner diameter D1 of the first bush 17a is smaller than the outer diameter D2 of the cylindrical body 16, the cylindrical body 16 can be easily inserted along the inclined portion 17e. For this reason, it is possible to facilitate the assembly work and obtain a sufficient waterproof and dustproof effect.

[0036] (Second modification example) FIG. 7 shows a first modification example of the present embodiment, and shows an enlarged view of the portion indicated by A in FIG. 5. In the second modification example, an annular contact portion 17f is provided on the inner surface of the first bush 17a. The contact portion 17f protrudes obliquely from approximately the central portion in the thickness direction toward the surface on the inner surface of the first bush 17a.

[0037] Specifically, in the second modification example, the inner diameter D4 of the first bush 17a is slightly larger than the outer diameter D2 of the cylindrical body 16 (D2 < D4), and the inner diameter D5 of the annular contact portion 17f is slightly smaller than the outer diameter D2 of the cylindrical body 16 (D5 < D2).

[0038] According to the second modified example, the inner diameter D4 of the first bushing 17a is slightly larger than the outer diameter D2 of the cylindrical body 16, and the contact portion 17f is provided at an angle along the insertion direction of the cylindrical body 16. This allows the cylindrical body 16 to be easily inserted into the first bushing 17a. Moreover, the inner diameter D5 of the annular contact portion 17f is smaller than the outer diameter D2 of the cylindrical body 16, so the contact portion 17f can be tightly attached to the cylindrical body 16. Therefore, the second modified example also makes it possible to simplify the assembly work and obtain sufficient waterproof and dustproof effects.

[0039] Moreover, since the tip of contact portion 17f is disposed toward the tip of cylindrical body 16, contact portion 17f acts like a valve when cylindrical body 16 is inserted inside first bushing 17a, thereby reliably preventing moisture and dust from entering gap G between first opening 15a and cylindrical body 16.

[0040] (Third Modification) FIG. 8 shows a third modified example of this embodiment, which is a further modification of the second modified example. In the second modification, the first bushing 17a has an annular contact portion 17f, whereas in the third modification, the first bushing 17a has an annular first protrusion 17g on its inner surface. The inner diameter D6 of the first protrusion 17g is, for example, the same as the inner diameter D5 of the contact portion 17f (D6=D5), but may be different.

[0041] According to the third variant, the first bush 17a has a ring-shaped first protrusion 17g on its inner surface, which provides the same waterproof and dustproof effects as the second variant and also simplifies the assembly process.

[0042] (Fourth Modification) FIG. 9 shows a fourth modified example of this embodiment, which is a further modification of the third modified example. In the third modification example, the annular first protrusion 17g is provided on the inner surface of the first bush 17a. In contrast, in the fourth modification example, the inner surface of the first bush 17a is flat, and an annular second protrusion 16b is provided on the outer peripheral surface of the cylindrical body 16.

[0043] Specifically, the inner diameter D4 of the first bush 17a is larger than the outer diameter D2 of the cylindrical body 16 (D2 < D4), and the outer diameter D7 of the annular second protrusion 16b is slightly larger than the inner diameter of the inner diameter D4 of the first bush 17a (D4 < D7).

[0044] According to the fourth modification example, since the inner diameter D4 of the first bush 17a is larger than the outer diameter D2 of the cylindrical body 16, the cylindrical body 16 can be easily inserted into the first bush 17a. Since the outer diameter D7 of the annular second protrusion 16b is larger than the inner diameter D4 of the first bush 17a, the second protrusion 16b and the first bush 17a can be brought into close contact with each other. Therefore, the assembly work can be facilitated, and a sufficient waterproof and dustproof effect can be obtained.

[0045] Moreover, since the shape of the first bush 17a can be simplified, it is possible to facilitate the manufacture of the sealing member 17.

[0046] In addition, the present invention is not limited to the above-described embodiments as they are, and at the implementation stage, the components can be modified and embodied without departing from the gist thereof. Also, various inventions can be formed by appropriately combining a plurality of components disclosed in the above-described embodiments. For example, some components may be deleted from all the components shown in the embodiments. Further, components from different embodiments may be appropriately combined.

Explanation of Reference Numerals

[0047] 10...torque sensor, 11...first structure, 12...second structure, 13...third structure, 15...cover, 15a...first opening, 15b...second opening, 16...cylindrical body, 16a...holder, 16b...second protrusion, 17...sealing member, 17a...first bushing, 17b...second bushing, 17c...cable bushing, 17d...groove, 17e...inclined portion, 17f...contact portion, 17g...first protrusion.

Claims

1. A cover having a first opening and a second opening continuous with the first opening at a portion around the first opening, the cover covering a portion of the structure; a cylindrical body disposed inside the first opening; a sealing member including a first annular bushing fitted between the first opening and the cylindrical body, and a second bushing connected to the first bushing and fitted into the second opening, the first bush and the second bush have grooves that are continuous around their peripheries and fit into the edges of the first opening and the second opening of the cover, a third bush provided on the second bush for holding a cable connected to a printed circuit board disposed inside the cover; A sealing structure characterized by comprising:

2. A sealing structure as described in claim 1, characterized in that the inner diameter of the first bush is smaller than the outer diameter of the cylindrical body, and the first bush has a sloped portion that slopes away from the inner surface of the first bush as it approaches the back surface of the first bush.

3. A sealing structure as described in claim 1, characterized in that the inner diameter of the first bush is larger than the outer diameter of the cylindrical body, and the first bush has an annular contact portion that protrudes obliquely from the inner surface of the first bush toward the surface of the first bush and contacts the outer surface of the cylindrical body.

4. A sealing structure as described in claim 1, characterized in that the inner diameter of the first bush is larger than the outer diameter of the cylindrical body, and the first bush has an annular first protrusion on its inner surface that contacts the outer surface of the cylindrical body.

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