1. Field of the Invention
The present invention relates to a solenoid drive apparatus that generates a magnetic force when the apparatus is energized.
2. Description of Related Art
A conventional solenoid drive apparatus includes a magnetic metallic body 1, a coil 2 and a metallic plate 3, as shown in FIG. 5. The body 1 houses the coil 2 and an opening portion of the body 1 is closed by the plate 3. The solenoid drive apparatus further includes a rubber sealing member 100, such as an O-ring, in order to limit water from entering from an exterior (see e.g., Japanese Unexamined Patent Publication No. 2001-182638). Here, the rubber sealing member 100 usually has a thickness of 1.5 mm or more.
However, the conventional solenoid drive apparatus has suffered from a degradation of a magnetic property (attractive force, responsibility) because of a magnetic block caused by the rubber sealing member 100, which is non-magnetic and has a large thickness. As a result, the conventional solenoid drive apparatus needs to have a larger coil 2 to compensate the degraded magnetic property. Also, a receiving groove 29, to which the rubber sealing member 100 is provided, has needed to be machined.
Further, there has been a fear of fault sealing because the sealing member 100 sometimes sticks out of the receiving groove 29 when the coil 2 is assembled to the body 1 or the plate 3. Further, there has been a fear of another fault sealing because a surface of the sealing member 100 is worn due to a friction of the sealing member 100 with the body 1 or the plate 3 when the coil 2 is assembled to the body 1 or the plate 3.