The above and other objects, features and advantages of the present invention will be described in more detail below based on preferred embodiments of the present invention with reference to the accompanying drawings, in which:
Several embodiments of a seal structure for an electric circuit unit according to the present invention will be described below with reference to the drawings.
First, referring to
The size-changing member 24 is intended to change the size of the opening 18 of the casing 14 so as to fit to the size of the outer periphery of the cable 16 and is arranged and fixed in contact with the shoulder 18c in the large-diameter portion 18b of the opening 18 of the casing 14. The size-changing member 24 may have any outer periphery of a suitable shape and size as long as if it can be accommodated in the large-diameter portion 18b of the opening 18 but cannot passage through the small-diameter portion 18a of the opening 18. However, a gap, into which the seal member 26 can be intruded when it is deformed in the large-diameter portion 18b, would lead to consumption of a part of deformation pressure acting on the seal member 26 to deform the seal member 26 into the gap, thereby making it impossible for deformation pressure to act efficiently in a diametrical direction. Therefore, in order to prevent such a gap from being formed, the size-changing member 24 preferably has the outer periphery of a shape and size substantially the same as or slightly smaller than the large-diameter portion 18b.
Further, the size-changing member 24 is formed at the central portion thereof with a through hole 24a for allowing the cable 16 to pass therethrough. The through hole 24a of the size-changing member 24 can have an appropriate size as long as it allows the cable 16 to pass therethrough. However, it preferably has a cross-sectional shape and size substantially the same as or slightly smaller than those of the outer periphery of the cable 16. The fact that the through hole 24a of the size-changing member 24 has a cross-section shape and size substantially same as or slightly smaller than those of the outer periphery of the cable 16 can prevent the formation of a gap which allows a deformed seal member 26 to intrude therein, thereby making it possible for deformation pressure to act efficiently in a diametrical direction.
The seal member 26 is arranged in the large-diameter portion 18b of the opening 18 of the casing 14 so as to be held between the size-changing member 24 and the fixed member 28, and is adapted to be pressed by the fixed member 28 and deformed in a diametrical direction in the large-diameter portion 18b of the opening 18 when pressure is exerted. The seal member 26 may have the outer periphery of an appropriate shape and size as long as it allows the seal member 26 to be accommodated in the large-diameter portion 18b of the opening 18 of the casing 14. However, it preferably has the outer periphery of a shape and size substantially the same as or slightly smaller than those of the cross section of large-diameter portion 18b of the opening 18. Also, the seal member 26 has an annular shape and is formed at the central portion thereof with a through hole 26a for allowing the cable 16 to pass therethrough. The through hole 26a of the seal member 26 may have a cross section of an appropriate shape and size as long as it allows the cable 16 to pass therethrough. However, it preferably has a cross section of a shape and size substantially the same as or slightly smaller than those of the outer periphery of the cable 16.
In a case where the seal member 26 has the outer periphery of a shape and size substantially the same as or slightly smaller than those of the cross section of the large-diameter portion 18b of the opening 18 and the through hole 26a of the seal member 26 has the cross section of a shape and size substantially the same as or slightly larger than those of the outer periphery of the cable 16, the seal member 26 can be brought into close contact with the inner peripheral surface of the large-diameter portion 18b of the opening 18 and the outer peripheral surface of the cable 16 just by being slightly deformed under light pressure, thereby securing a sufficient seal.
The fixed member 28 includes a fitting portion 28a to be fitted in the large-diameter portion 18b of the opening 18 of the casing 14 and a flange portion 28b extending in a diametrical direction from the outer periphery of the fitting portion 28a. The flange portion 28b is formed with a plurality of mounting holes 28, and the fixed member 28 is fixed to the casing 14 by fasteners 30, such as screws or rivets inserted through the mounting holes 28c. When the fixed member 28 is fixed to the casing 14, the fitting portion 28a is fitted in the large-diameter portion 18b of the opening 18 and presses and deforms the seal member 26. Also, the fixed member 28 is formed at the center thereof with a through hole 28d for allowing the cable 16 to pass therethrough. The through hole 28d of the fixed member 28 may have the cross section of an appropriate shape and size as long as it allows the cable 16 to pass therethrough. However, it preferably has the cross section of a shape and size substantially the same as or slightly larger than those of the outer periphery of the cable 16. As described above, the configuration in which the through hole 28d of the fixed member 28 has the cross section of the shape and size substantially same as those of the outer periphery of the cable 16 makes it possible for pressure to efficiently act on the seal member 26. Therefore, a sufficient seal can be secured.
In assembling the seal structure 20 shown in
Since the presence of the size-changing member 24 makes it possible to design the opening 18 of the casing 14 to have a sufficient size to allow the connecting member 22 to pass therethrough, as described above, the cable 16 can be inserted through the opening 18 of the casing 14 even with the connecting member 22 attached to the forward end of the cable 16. Therefore, a subassembly can be prepared in advance by passing the cable 16 through the size-changing member 24, the seal member 26 and the fixed member 28 and attaching the connecting member 22 to the forward end of the cable 16. This can eliminate the work of attaching the connecting member 22 to the forward end of the cable 16 within the narrow inner space of the casing 14 and simplify the attaching work required to do on site. Further, even in the case where the cross section of the small-diameter portion 18a of the opening 18 is so large that a large gap is left between the inner peripheral surface 18a of the small-diameter portion 18a and the outer peripheral surface of the cable 16, the size-changing member 24 blocks at least part of the inlet to the gap to prevent the deformed seal member 26 from intruding through the inlet into the small-diameter portion 18a. As a result, the pressure exerted on the seal member 26 by the fixed member 28 is efficiently converted into the deformation force in such a direction as to bring the seal member 26 into contact with the outer peripheral surface of the cable 16 in the large-diameter portion 18b and the inner peripheral surface of the opening 18, thereby making it possible to secure a sufficient sealability.
Next, referring to
In the above embodiments, each of the size-changing member 24 and seal member 26 preferably has a cross section of a disk-like shape formed with an opening, as shown in
Number | Date | Country | Kind |
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2006-201311 | Jul 2006 | JP | national |