US20080128206A1

US20080128206A1 - Drain bolt

Info

Publication number: US20080128206A1
Application number: US11/566,740
Authority: US
Inventors: John A. Wilkins
Original assignee: SKF USA Inc
Current assignee: SKF USA Inc
Priority date: 2006-12-05
Filing date: 2006-12-05
Publication date: 2008-06-05

Abstract

A drain bolt which includes a threaded shank portion, a driving head, and an enlarged primary flange and a pair of secondary circular flanges of reduced diameter with respect to said enlarged flange, said reduced diameter flanges holding a captive O-ring between them. The seal is between a cylindrical counterbore and the O-ring, and is completely independent of the force with which the drain bolt is installed.

Description

BACKGROUND OF THE INVENTION

The present invention relates to an improved drain bolt concept, and in particular to a drain bolt which includes a threaded shank portion, an O-ring retained in a cylindrical counterbore and in which the bolt includes a driving head and a enlarged flange which abuts the marginal portions of the counterbore formed in the oil pan or other oil-containing opening.
Because of the importance of the removable bolt in an oil pan or the like, many proposals have been made. For example, some plugs or other fittings have been proposed which include a threaded shank portion in place for accommodating an O-ring and a frusto-conical portion of the fitting which mates with the frusto-conical portion of the oil pan or the like. Such high pressure fittings relate to the frusto-conical portion in which an O-ring is compressed to a certain variable extent determined by the tightness fitting. Such a construction is described in U.S. Pat. No. 3,893,487.
A similar construction shown in U.S. Pat. No. 3,933,358, which includes a deformable O-ring subject to being compressed by a fitting to a greater or less extent, depending on the tightness of the fitting.
A similar construction involving the compression of the O-ring in a frusto-conical seat is described in U.S. Pat. No. 5,107,808.
Another form of crankcase drain plug is disclosed in U.S. Pat. No. 5,547,042. Still another patent involving an deformable O-ring is shown in FIG. 4 of U.S. Patent Application publication number 2006/0037427A1.
Another drain plug construction is shown in Application Publication US2006/0054402A1, wherein an O-ring is shown being compressed by a complex structure in a couple of different embodiments.
U.S. Pat. No. 6,752,174 shows an O-ring or the like which is situated somewhat down along the threaded shank portion of what is identified as a safety plug.
Finally, another construction is shown in U.S. Pat. No. 4,938,314. This shows an O-ring situated in a groove, but the groove lies in a slight taper and, the oil drain plug is screwed into a threaded bore in an insert. The insert is used because of the plastic construction of the oil pan.
In none of the above constructions is a drain bolt shown wherein the sealing of the drain bolt takes place entirely independently of the torque with which the drain bolt is installed and the head lies outside of the O-ring(s).
In view of the shortcomings listed above is, it is object to present invention to provide an improved drain bolt construction.
Another object of the invention is to provide a drain bolt construction which includes a pair of flanges separated by an O-ring grove and located on an upper portion of the drain bolt.
A still further object is to provide a drain bolt with a threaded shank portion, a pair of spaced apart circular flanges adapted to surround an O-ring, and a right circular cylindrical flange surmounted by a driving head.
Yet a further object of the invention is to provide a drain bolt having a captive O-ring and wherein the O-rings is seated in a smooth cylindrical counterbore and in which therefore there is no relation between the torque applied to the bolt for sealing purposes and the shape or sealing ability of the O-ring.

SUMMARY OF THE INVENTION

According to the present invention, therefore, the drain bolt contains a threaded shank for fitting directly into the oil pan, and a pair of spaced apart circular flanges comprising an O-ring groove, wherein the O-ring is permanently seated. Spaced axially apart and away from liquid being contained is first an O-ring groove, and secondly, an enlarged, preferably circular flange, which in turn is surmounted by a driving head. Thus, the bolt is received with its shank portion received within a threaded bore, a smooth, circular cylindrical counter bore is provided wherein the O-ring is seated, and an enlarged flange and driving head are also provided.
The manner in which the invention achieves its objects and other objects and advantages will become more apparent when considered in connection with the following detailed description of the preferred embodiment of the invention and shown in the accompanying drawings in which like reference numbers indicated corresponding points throughout.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view, with a portion broken away, of the drain bolt of the invention, including the pair of circular flanges holding a captive O-ring between them and enlarged right circular cylindrical flange surmounted by a driving head;

FIG. 2 is similar to FIG. 1, but showing a drain bolt with a portion broken away, and showing an Allen head socket, without the O-ring in place; and

FIG. 3 is a perspective view, with a portion broken away, showing the drain bolt in position of use within an oil pan or like, and showing an alternate optional means for driving the bolt.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

The invention can be practiced in several ways, but two preferred embodiments of wells or socket for receiving an Allen wrench or a Phillips head driver, plus the bolt having a hex head are shown.
Referring now to the drawing in greater detail, FIG. 1 shows a drain bolt generally designated 10 adapted to be received within an opening generally designated 12 in an oil pan 14. The bolt includes a lower, entry portion 16, a lower threaded shank portion 18 and a lower circular flange 20 having a optional bevel 22 therein. The circular flange 20 is spaced apart from the substantially identical upper circular flange 24, with the space 26 (FIG. 2) retaining a snugly engaged O-ring 28.
Lying above the upper circular flange 24 is an enlarged right circular cylindrical flange 30. Surmounting the flange 30 is a driving head generally designated 32. The driving head 32 has six flanks 34, arranged in a hex pattern. Other formations may also be provided, of course.
Such a head 32 may have other or additional driving means, such as a well or socket 36 for accommodating a hex head Allen wrench 37, or having such sides arranged in patterns such as those used by a Torx fastener on the like. The opening 38 in FIG. 3 may also accommodate a Philips head screwdriver or wrench in addition to the flanks 34.
The oil pan opening 14 has a threaded interior bore 40, a step 42, and a smooth counterbore 44 extending axially and ending in a flat exterior margin 46. The margin 46 abuts the lower surface 48 of the flange when the bolt is fully installed.
Upon initially preparing to install an O-ring over the drain bolt, the O-ring is preferably coated with a Teflon™-containing lubricant or the like. The O-ring maybe dipped in the lubricant or the lubricant maybe sprayed on, depending on the desire of the user. The application of such a lubricant in some other way would also be satisfactory. Once the bolt is placed in use, oil will inherently coat the O-ring sufficiently and no further steps relative to lubrication need be taken when the drain bolt is removed and reinstalled.
Accordingly, the main advantage of drain plugs such as those described is that the torque or twisting movement with which they are installed has no bearing whatsoever on the degree of sealing. Thus, if the radial force with which the O-ring bears on the groove 26 and the counterbore 44 is sufficient, then the axial force which is generated by the bolt and however tight it may be is completely independent of this sealing force. This is, of course, provided that the face 23 of the lower cylinder is always spaced from the surface 42, then the torque will be generated entirely by the resistance between surfaces 46, 48.
The enlarged cylindrical flange 30 is shown as being orthogonal. Of course, if the flange 30 were frusto-conical, then the mating surface 46 should also be inclined to the same degree.
It will thus be seen that the present invention provides a drain bolt having a number of advantages and characteristics, including those herein pointed out and others which are inherent in the invention.

Claims

1. A drain bolt adapted to create a seal for an oil receptacle or the like, said oil receptacle having a threaded region, a smooth cylindrical counterbore extending outwardly from said threaded region and terminating in a first radially extending surface, said drain bolt comprising, in combination, an axially lower, threaded shank portion, an uppermost, driving head portion, and lying immediately beneath said driving head portion, a cylindrical primary flange of a given diameter, and beneath said primary flange a pair of cylindrical flanges of reduced diameter relative to the diameter of said primary flange and enlarged diameter relative to said threaded shank portion, said two circular flanges being spaced apart so as to provide a radially extending groove therebetween for receiving an elastomeric O-ring serving as a seal between said bolt and a counterbore spaced from said circular flanges by a working clearance, said bolt providing a sealing force entirely independent of the torque applied to said head portion.

2. A drain bolt as defined in claim 1 wherein said driving head portion is hexagonal in shape.

3. A drain bolt as defined in claim 1 wherein said driving head portion is square in shape.

4. A drain bolt as defined in claim 1 wherein said driving head portion includes a Phillips head portion.

5. A drain bolt as defined in claim 1 wherein said driving head portion is a socket for receiving an Allen wrench.

6. A drain bolt as defined in claim 1 wherein said primary flange lies in a flat plane.

7. A drain bolt as defined in claim 1 wherein said shank portion includes a lowermost entry portion free from threads.