JPS6260910A - Drain plug - Google Patents

Abstract

PURPOSE:To prevent the breakage of a case screw hole by providing a circumferential groove reducing thickness between a bolt-shaped head and a screw part, and providing a square hole reaching from the head to the screw part at the center, in a drain plug for an oil pan to be used for vehicle. CONSTITUTION:In a drain plug 1, a circumferential groove 4 is provided between a bolt-shaped head 2 and a screw part 3 so as to reduce the thickness thereof and to be broken earlier than the screw thread to be screw-fitted on the case side, and a square hole 5 reaching to the screw part 3 is provided in the center. And, while the drain plug 1 is screw-fitted in the screw hole on an aluminum case 6 in which lubricating oil is enclosed, in this case, if it is tightened with a torque more than required, the part provided with the groove 4 is first broken. When broken, since the head 2 falls out and the screw part 3 remains in the screw part of the case 6 as it is screw-fitted, it is drawn out by inserting a square wrench into the square hole 5. Thus, the breakage of the screw hole on the case can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a drain plug provided in an oil pan at the bottom of a transmission case or an engine case.

[Technical background and problems of the invention]

Some transmission cases and engine cases have lubricating oil sealed inside to lubricate various parts. In this case, make a screw hole at the lower end of the transmission case or the lower end of the oil pan at the bottom of the engine case, and screw a bolt-shaped drain plug into it.If the lubricating oil inside becomes dirty, remove the drain plug. This makes it possible to remove dirty lubricating oil. by the way,
Recently, engine cases and transmission cases are often made of lightweight alloys by casting. In this case, if an unskilled person tightens the drain plug, the drain plug may be tightened with more torque than necessary, which may damage the screw in the screw hole on the case side, which is made of soft material. If this happens, you won't be able to tighten it properly, and you won't be able to use it unless you increase the thread diameter, cut it again, and screw in a thicker drain plug. Moreover, if the drain plug is not oversized, the case becomes unusable and needs to be replaced, which is expensive and inconvenient.

[Purpose of the invention]

In view of this, the present invention is to screw a drain plug into a screw hole in an aluminum alloy case.If the drain plug is tightened with more torque than necessary, the drain plug will break first and remain in the screw hole. To provide a drain plug whose parts can be easily removed and a new drain plug can be used immediately.

[Structure of the invention]

Embodiments of the present invention shown in the drawings will be described below.

The drain plug has a bolt-like shape with a hexagonal head so that a wrench can be applied to it, and it is thinned between the threaded parts 3 so that it will break off before the thread on the case side to which it is screwed. It was set up by Hiroshi Shuzo. A square hole S with a square or hexagonal cross section is provided from the head part 2 to the screw part 3. 6 is an aluminum case, and 7 is a packing.

Thus, the drain plug l is screwed into a screw hole provided in the aluminum case B containing lubricant oil. When tightening, if you tighten with more torque than necessary, the circumferential part will be weakened, so before the screw hole in the aluminum case B is damaged, the circumferential groove ta will be cut off and the drain will be damaged. Plug L breaks first. When the drain plug is damaged, the head unit falls out and the threaded part 3 remains screwed into the threaded hole of the aluminum case 6. This remaining head λ
can be removed by inserting a square spanner into the square hole and turning it. Therefore, a new drain plug can be used immediately, and it is only necessary to replace the drain plug.

〔Effect of the invention〕

As explained above, this invention provides a drain plug with a thin circumferential groove between the bolt-shaped head and the threaded part, and a square hole in the center extending from the head to the threaded part. When tightening the drain plug to the threaded hole in the case, if the tightening is too strong, the drain plug will always break at the circumferential groove part before the threaded part of the case, which can prevent damage to the threaded hole in the case. Then, the threaded part of the drain plug remaining in the screw hole can be removed by inserting a square wrench into the square hole.
It can be easily removed. This way, you only need to break the drain plug, and you won't have to replace the expensive case. In this way, damage to the case can be prevented, so there is no need to add more weight to the case to maintain its strength (and it also reduces weight).

[Brief explanation of the drawing]

The figures show one embodiment of the present invention, with FIG. 1 being a partially longitudinally sectional front view and FIG. 1 being a plan view. l...drain plug, c...head, 3...screw part, l...circumferential groove, 5...square hole.

Claims (1)

[Claims] A thin circumferential groove is provided between the bolt-shaped head and the threaded part,
A drain plug characterized by a square hole in the center extending from the head to the threaded part.