US3361288A

US3361288A - Core plug

Info

Publication number: US3361288A
Application number: US530135A
Authority: US
Inventors: Jack R Dorman
Original assignee: Individual
Current assignee: DORMAN ACQUISITION CORP A CORP OF DE
Priority date: 1966-02-25
Filing date: 1966-02-25
Publication date: 1968-01-02
Anticipated expiration: 1985-01-02

Description

Jan. 2,1968 J. R. DORMAN 3,361,288

CORE PLUG Filed Feb. 25, 1966 Z4 Z5 INV TIOR.

I:'5I..5 kw? nmdmizum ATTORNEYS.

United States Patent 3,361,288 CORE PLUG Jack R. Dorman, 5757 Mariemont Ave, Cincinnati, Ohio 45227 Filed Feb. 25, 1966, Ser. No. 530,135 8 Claims. (Cl. 22024.5)

This invention relates to core plugs. These plugs are employed to close and seal the holes that are required in cast internal combustion engine blocks in order to remove the material used in the casting process to form the internal channels for coolant fluids. The locations of these holes in the engine block primarily are dictated by foundry practices and they often are located such that it is difficult for a mechanic to replace one should this be required. Leakage or even loss of a plug is not uncommon, and at times it is necessary for a mechanic to remove a number of engine parts in order to gain access to a leaky plug. The removal and replacement of the plug itself is a matter of minutes but the removal and replacement of engine parts in order to gain access to the plug may take many hours.

This invention is directed to a core plug that makes it unnecessary to remove engine parts in order to replace a faulty core plug.

In general there are two types of core plugs that have been used in the past as original equipment and as replacement equipment. One is a shallow cup, the walls of which are tapered slightly so that the cup may be press fitted into the core hole and held therein by friction. To replace a cup type core plug there must be a substantial amount of space available to accommodate a tool such as a hammer by which the plug may be driven or forced into the core hole. Another type is a disk that is concave on that face Which is placed into the core hole and convex on that face which is to the outside. The disk type plug is locked in place to close and seal the opening by striking it with a tool such as a hammer to flatten it and thereby expand it radially. Here again it is impossible to properly fit a plug of this type unless there is ample room to manipulate the fitting tool.

In the core plug of this invention the plug is adapted to be held or initially fitted within the core opening by means such as a wrench and then expanded to close and seal the opening by means of a second Wrench. These two wrenches do not necessarily have to approach the plug location from the same direction and it is found that even though a core opening be virtually inaccessible to a persons hand, the opening can be reached first by the wrench that is used to initially place the plug in the core opening and then the plug expanded by a second wrench, preferably a ratchet type Wrench that is adapted to be manipulated in close quarters.

In the case of a leaky plug that is in an inaccessible location it is found that it can be removed by driving a sharp instrument into it and then prying it from the hole. This requires little space and the approach can be made from any direction and removal presents no problem. Further, in the past it has been the practice to clean out the core opening before replacing a plug and then to use a sealing compound that is applied to those surfaces contacted by the plug. In order to accomplish the cleaning and the application of a sealing compound it required that there be a sufliciently large enough opening to the core hole to permit a mechanic to get his hand to the hole. This is not necessary with the plug of this invention because it can be expanded to such an extent and with such force that metal of the plug actually flows to fill scoring marks and such intimate contact is made with the Wall of the opening that no sealing compound is required to prevent leakage. This is particularly important in modern automobile engine blocks wherein pressures of up to and beyond 14 pounds per square inch of the coolant fluids are developed. In actual test the plug of this invention was found to withstand internal pressures as high as 70 pounds per square inch, indicating the intimacy of the seal and the radial pressures developed within the plug.

Thus, the primary objective of this invention has been to provide a core plug that can be used to replace leaking or missing core plugs that are located in diflicult to reach places in an internal combustion engine block.

Another objective has been to provide a core plug that is adapted to withstand substantially greater internal pressures than plugs of the past and to require no cleaning of the surface of the core opening or a sealing compound upon the plugs being set in place.

One cause for core plug failure has been the electrolytic action that takes place in certain types of fluids where two different metals contact one another. It has been another objective of this invention to provide a core plug of the type set forth wherein the corrosive effects of electrolysis is inhibited to an extent that it is failure free under conditions wherein plugs of the past would have been destroyed.

Because the plug of this invention is designed to be utilized in places where it cannot be closely inspected, it has been a further objective to provide a means of indicating to a mechanic the amount that the plug is expanding while an installation is being made. Toward this end the plug is designed to expand predetermined amounts depending upon the number of turns that are given an acorn nut by means of the wrench that is employed to expand the plug. This same relationship is adapted to be built into plugs of different sizes so that a mechanic knowing this can use the same installation techniques for plugs of all sizes incorporating the principles of this invention.

These and other objectives and advantages of the invention will be readily apparent to those skilled in the art from the following detailed description of the drawings in which FIGURE 1 is a side elevational view of a core plug shown installed in the wall of a portion of an engine block that is illustrated diagrammatically only.

FIGURE 2 is a side elevational view showing the four basic parts comprising the plug of this invention.

FIGURE 3 is an elevational View showing the outer face of the plug of FIGURE 1.

FIGURE 4 shows the inner face thereof.

FIGURE 5 is an enlarged cross sectional View taken on a plane through the longitudinal central axis of the plug.

Referring to FIGURE 2, the plug consists essentially of an outer shell 10, a brace or stiffener disk 11, an expander disk 12 that comprises an assembly in combination with a large headed bolt 13 and an acorn nut 14-.

The shelllll, in the preferred embodiment, is made of a soft copper that is capable of flowing under high pressures of the type that can be developed during an installation of the plug of this invention. It includes a rim portion 15. It is preferred, although unnecessary, that this rim be given a slight taper in order to assist the initial insertion of the plug into a core opening. The outer face of the plug shell is configuratcd as shown at 16 to provide a hexagonal projection to receive the jaws of a wrench. The annular area between the hexagonal projection of the rim portion 15, which is identified by the numeral 17, is formed as an integral part of the shell so that the shell is unbroken except for a central opening shown at 18 in FIGURE 5 through which the threaded shank 19 of bolt 13 may project. The outer face 2% of the hexagonal projection 16 of the shell is flat and, since the shell is made of a relatively soft copper material, this portion of the shell acts as the equivalent of a copper washer when the acorn nut 14 is tightened snugly in place against the face 2d at the time of an installation, thereby providing a seal to prevent leakage at this point. Also, as will be seen, there is little chance of leakage from the inside of an engine block to this point.

The brace disk 11 is the backbone of the plug and it must be sufiiciently strong to absorb the stresses that are developed within the plug. It is found that a material such as 13-gauge steel works well for this disk. By contrast, the copper shell may be as thin as 0.05 inch. The disk 1'. is configurated to rest within the copper shell ltl so that it presents an annular face 2 1 to the rear surface of that area of the front face 2% of the hexagonal projection against which the acorn nut 14 is tightened at the time of installation. Thus, the outer annular area 22 of the brace disk is offset inwardly with respect to the annular backup portion 21. The disk 11 is of a diameter such that its rim 23 fits the inner surface of the rim portion of the shell in slipfit relation.

The expander disk 12 is made of a material such as 16-gauge steel and it is adapted to be seated within the rim portion 15 of the copper shell lid in slipfit relation, presenting its rim 24- to the inside surface of the rim portion 11 and making contact with the rim 23 of the brace disk 11. Preferably, the expander disk 12 is just slightly larger in diameter than the bracer disk 11.

Bolt 13 has a large flat head 25. That portion of the bolt immediately inside of the head designated 26 is splined and it is of a diameter such that when it is pressed into a central hole 27 in the expander disk, an exceedingly tight juncture is made. It is preferred that this joining operation be made under high pressure in order to achieve a fit in which the metals of the expander disk and the shank portion 26 of the bolt Weld to one another.

Both the plug expander and the bolt in its entirety are copper plated in order to resist the corrosive effects of the coolant fluids within the engine plug. It is preferred that a substantially thick plating be used and this plating of the splined area 2 5 and the central hole 27 through which the bolt passes ensures that an exceedingly intimate seal be achieved between the bolt and the expander disk.

With the parts of the plug assembled as shown in FIG- URE 5 the hexagonal projection 16 is placed in the jaws of a wrench. It is preferred that the wrench used be one that can be adjusted to a point where plug assembly may be manipulated by the wrench. The plug is then inserted into a core opening, as illustrated in FIGURE 1, of the wall of an engine block shown diagrammatically only at 28, the broken side designated 29, indicating the wall of the cavity inside of the engine block. As is the usual practice, a shoulder 30 is provided within the opening. The plug is inserted until the rim 15 of the shell contacts shoulder 3%. At this point the acorn nut i i is engaged by a second wrench, preferably a ratchet wrench. At this time the plug is loosely engaged in the core Opening. However, by holding it in place with the wrench engaged on the hexagonal portion 16, the ratchet wrench may be worked without having the plug turn within the hole and this is continued until the expander disk 12 is warped toward its being a straight disk to a point where intimate contact is achieved bet-ween rim 15 and the wall of the core opening. At this point the first Wrench is no longer required and expansion of the plug can be continued by the use of the ratchet wrench only. It is found that in a plug wherein a 1.63 diameter size is required (which is undersize with regard to the opening of a core hole) and wherein an expander disk is employed that is 1.54 inches in diameter and of 16-gauge steel and curved on a radius of 2% inches and further wherein inch standard threads are employed for bolt 13, the first complete turn of the acorn nut expands the plug 0.007 inch. The second complete turn of the acorn nut is found to cause an additional 0.011 inch of expansion. The third complete turn of the acorn nut causes an additional 0.007 of an inch of radial expansion. It is preferred that the nut be so designed that it bottoms at this point to prevent unknowing mechanics from building up excessive stresses Within the plug. The reason that the third turn causes a decrease in the amount that the plug expands is because at this point there is so much pressure on the rim 15 of the copper shell that there is a substantial amount of metal flow axially. In actual practice no more than two turns of the acorn nut have been found to be required, most installations requiring only one or just slightly more than one. In any event, by having the relationships described for the various parts it is possible for the mechanic to know to within a few thousandths of an inch the exact amount of expansion that has occurred simply by his observing the number of complete turns made by the acorn nut. Obviously, this relationship can be built into plugs of various diameters.

It will be noted that in the preferred embodiment the bracer disk absorbs the stresses that are placed upon the shell by the tightening of the nut and that it also absorbs the forces placed upon its rim by the expander disk such that no undue stresses are placed upon the relatively thin copper shell 10.

Having described my invention I claim:

1. A core plug assembly adapted for use in core holes that are in difficult to reach locations on engine blocks, said plug comprising a shell having a circular rim portion and an outer face portion,

said rim portion initially being of a diameter that is slightly smaller than a core hole in which the plug is to be used,

the outer face of said shell having a projection thereon that is configurated to receive a tool by means of which said assembly may be held and manipulated,

an expander disk that is of a diameter to initially fit within said rim portion in slipfit relation,

said expander disk being concave and adapted to be seated within said rim portion with the concave face thereof toward such shell portion,

a brace disk adapted to be seated within said shell between said expander disk and the outer face portion of said shell,

said brace disk having a central portion adapted to contact the rear face of the central portion of said projection and having an outer annular area adapted to contact that part of said outer face portion surrounding said projection,

there being a central opening in said expander disk, said brace disk and said outer projection,

a large headed bolt extending through said expander disk, said brace disk and said outer projection, said bolt having threads thereon,

and an acorn nut adapted to be engaged upon said threads such that the tightening of said nut causes said expander disk to be deformed radially outwardly for expanding said rim portion into intimate contact with the wall of a core hole.

2. A core plug assembly as set forth in claim 1 in which said shell is made of copper and said expander disk and said bolt are plated with copper.

3. A core plug assembly as set forth in claim 1 in which the degree of expansion of said expander plug is directly related to the number of turns given the acorn nut upon the tightening thereof.

4. A core plug assembly as set forth in claim 2 in which the projection on said shell has a flat face in the area thereof against which said acorn nut engages upon the tightening thereof, whereby said flat area serves as a copper washer to provide a seal.

5. A core plug assembly as set forth in claim 1 in which said brace disk is more resistant to deformation than said expander disk.

6. A core plug assembly as set forth in claim 1 in which said shell is of soft copper and adapted to flow under high pressures.

("3 7. A core plug assembly as set forth in claim 1 in References Cited which said projection is hexagonal and adapted to receive UNKTED STATES yATENTS Wrench- 2,996,214 8/1961 Kemble 220-245 3. A core plug assembly as set forth in claim 1 1n 3,175,727 3/1965 PM 220M245 which said bolt bot-toms in said acorn nut prior to the 5 I expander disk being deformed to its maximum radial THERON CONDON Y EMYTWW- expansion. G. T. HALL, Examiner.

Claims

1. A CORE PLUG ASSEMBLY ADAPTED FOR USE IN CORE HOLES THAT ARE IN DIFFICULT TO REACH LOCATIONS ON ENGINE BLOCKS, SAID PLUG COMPRISING A SHELL HAVING A CIRCULAR RIM PORTION AND AN OUTER FACE PORTION, SAID RIM PORTION INITIALLY BEING OF A DIAMETER THAT IS SLIGHTLY SMALLER THAN A CORE HOLE IN WHICH THE PLUG IS TO BE USED, THE OUTER FACE OF SAID SHELL HAVING A PROJECTION THEREON THAT IS CONFIGURATED TO RECEIVE A TOOL BY MEANS OF WHICH SAID ASSEMBLY MAY BE HELD AND MANIPULATED, AN EXPANDER DISK THAT IS OF A DIAMETER TO INITIALLY FIT WITHIN SAID RIM PORTION IN SLIPFIT RELATION, SAID EXPANDER DISK BEING CONCAVE AND ADAPTED TO BE SEATED WITHIN SAID RIM PORTION WITH THE CONCAVE FACE THEREOF TOWARD SUCH SHELL PORTION, A BRACE DISK ADAPTED TO BE SEATED WITHIN SAID SHELL BETWEEN SAID EXPANDER DISK AND THE OUTER FACE PORTION OF SAID SHELL, SAID BRACE DISK HAVING A CENTRAL PORTION ADAPTED TO CONTACT THE REAR FACE OF THE CENTRAL PORTION OF SAID PROJECTION AND HAVING AN OUTER ANNULAR AREA ADAPTED TO CONTACT THAT PART OF SAID OUTER FACE PORTION SURROUNDING SAID PROJECTION, THERE BEING A CENTRAL OPENING IN SAID EXPANDER DISK, SAID BRACE DISK AND SAID OUTER PROJECTION, A LARGE HEADED BOLT EXTENDING THROUGH SAID EXPANDER DISK, SAID BRACE DISK AND SAID OUTER PROJECTION, SAID BOLT HAVING THREADS THEREON, AND AN ACORN NUT ADAPTED TO BE ENGAGED UPON SAID THREADS SUCH THAT THE TIGHTENING OF SAID NUT CAUSES SAID EXPANDER DISK TO BE DEFORMED RADIALLY OUTWARDLY FOR EXPANDING SAID RIM PORTION INTO INTIMATE CONTACT WITH THE WALL OF A CORE HOLE.