US2436712A - Moisture shield for spark plugs - Google Patents

Description

Feb 24, 1948. l 5. G. BURRELL Er AL I 2,435,712

MOISTURE SHIELD FOR SPARK PLUGS Filed July is, 1946 4'/ JNVENToR.

G50/Q65 6. Q1/RMLL BY ARTHUQ l. HuLsH/zm AGI/vr Patented Feb. 24, 1948 UNITED STATES PATENT GFFICE 2,436,112 MOISTURE SHIELD Fon SPARK PLUGS Application July 13,' 1946, Serial No. 683,564

8 Claims. l

This invention relates to spark plugs and has particular relation to means for moisture proofing the electrical connection to such plugs.

It is the primary object of our invention to provide an improved moisture shield for use in conjunction with spark plugs and one which is adapted to protect the plug and its electrical connection from shorting out or becoming in-operative due to moisture conditions from causes such as rain or condensation or the like.

Another primary object of our invention is the provision of a moisture shield which is adapted to be employed in conjunction with spark plugs of varying sizes and shapes.

A further object of our invention is the provision of a moisture shield which is adapted to be employed in conjunction with spark plugs of varying sizes and shapes.

A further object of our invention is the provision of an extremely simple moisture shield of this nature which may be manufactured at a relatively low cost and which may be quickly and easily installed.

It is a still further object of our invention to provide a moisture shield of this character having a resilient sealing member which is so mounted as to eliminate the continual distortion and deformation to which such devices of the prior art have been subjected.

It is another obiect of our invention to provide an improved seal between a moisture shield and the spark plug with which it is to be used.

Other and further features and objects of the invention will be more apparent to those skilled in the art upon a consideration of the accompanying drawings and following specication. wherein are disclosed exemplary embodiments of the invention, with the understanding, however, that such changes may be made therein as fall Within the scope of the appended claims, without departing from the spirit of the invention.

In the drawings:

Figure 1 is a view in elevation of a spark plug embodying a moisture shield constructed in accordance with a preferred embodiment of my invention.

Figure 2 is an enlarged partial view of the same plug and moisture shield with the moisture shield shown in section to better illustrate the structure thereof.

Figure 3 is a view in section of a portion oi the moisture shield of the device shown in Figure 2, along with the preferred form of resilient sealing member.

Figure 4 is a view, partly in elevation and partly in section, illustrating the same moisture shield and sealing member when applied to a spark plug of a different shape. and

Figure 5 is a sectional view showing details of a modified form of sealing member.

Referring now to these drawings, and in particular to Figures 1 to 3 inclusive thereof; the spark plug which I have indicated generally at Il includes the hollow metal body I2 having the threaded portion I3 at its lower end, a porcelain insulator I4 extending upwardly through the center thereof, and a centrally disposed electrode I5 extending upwardly through the center of the porcelain insulator and terminating at the top thereof in the threaded terminal I6. The porcelain insulator illustrated in Figure 2 is one of the type having smoothly tapered side walls.

The moisture shield comprises in general a lower, flexible or rubber-like sealing member I1, a lower shield I8, disposed immediately above the sealing member and secured in place by the pointed stylus I9 which is threadedly received on the terminal I6. An upper shield 20 is adapted to support and provide a seal with the ignition cable 2|.

The lower sealing member I'I is preferably made of a rubber-like material such as Neoprene, which is also more or less heat and oil resistant. It may be made in the shape illustrated in Figure 3 with a downwardly cupped top wall 22 having straight side wall portions 23 at the upper outer edge thereof, and an opening through the center as at 24 for reception over the spark plug terminal I6. The annular-shaped, depending side walls 24 preferably converge inwardly at the bottom, and are also preferably of somewhat thinner section at the bottom, as shown Aat 25.

The lower shield or body portion I8, preferably of molded plastic or the like, is annular in shape with the bottom wall 26 thereof provided with an opening 21 for reception over the terminal I6 and also recessed as at 28 to receive the upper wall 22 of the sealing member Il. The recess 28 is preferably made with a substantially vertical slde wall portion 23A, and a downwardly and outwardly slanting face 29 as an aid in preventing the entrance of any moisture. The annular upper portion 30 of the lower shield is threaded on its outside as at 3l to receive the internally threaded upper shield 20. The well 32 within the upper portion of the lower shield provides for the reception of a washer 33 and the pointed stylus IS.

The stylus I9 is preferably turned from hexagonal stock so as to provide a hexagonal base y as an aid in installing or assembling the device.

The upper shield 20, which may also be of molded plasticor the like, is generally conical in shape with an opening 35vthrough Vthe top thereof for the reception of the ignition cable 2l. This opening 35 is'preferably slightly tapered,

i and the stylus I 9' is of such length as to extend .out and expand laterally to completely fill the recess 28 in the base of the lower shield I8. The annular, converging, sleeve-like side wall 24 is preferably molded in such size as to engage the porcelain of a relatively small-size plug, and when the sealing member is installed on the plug and caused to atten out by screwing the stylus i9 downwardly, the lower converging wa11s'24 tend to contract or converge even more and thus provide a tight seal against the porcelain of the plug.

It is now apparent that an electrical contact is established between the upper terminal IB of the spark plug and the centrally disposed conductor of the ignition cable 2l. A tightly sealed enclosure is provided to entirely enclose this electrical connection. No moisture may enter this enclosure through either the opening 35 in the top shield, through the threaded junction between the'upper and lower shields, through the sealed junction between the lower shield and the lower sealing member, or between the lower sealing member and the porcelain of the plug. It will be noted also that the sealing portion of the lower iiexible sealing member serves only to provide a seal. It is not required to support the ignition cable or to stand any lateral strain and consequent deformation due to the weight or to the frequent movement of the ignition cable.

The same moisture shield structure and sealing member is illustrated in Figure 4 in conjunction with a spark plug having a porcelain insulator of different shape, and illustrates the manner in which the lower sealing member I1 is adapted to closely engage and conform to the different form of plug insulator 31.

'A modified form of lower sealing member and lower shield, as illustrated in Figure 5, is similar to the structure shown in Figure 3, except that the upper wall 38 of the lower sealing member 39 is not adapted to be expanded within the recessed bottom of the lower shield 40. The lower shield 40 is recessed in such a. manner as to provide a narrow rim along its outer edge as at 4|, and the substantially straight or fiat top Wall 38 of the lower sealing member is caused to cup upwardly within the recess in the bottom of the lower shield when installed over the terminal of the plug and substantially in the same manner as in the device shown in Figure 2. A seal is thus provided between the lower sealing member 39 and the lower shield I0. The lower converging walls 42 of the lower sealing member are also urged inwardly to closely engage the outer surface of the plug on which it is installed.

Although we have described specic embodiments of our invention, it is apparent that modifications thereof may be made by those skilled in the art. The lower sealing member may, for

example,` be made of somewhat differentshape than that shown in either'Figure 3 or 5. The narrow ange 4I, providing the spacer between the lower sealing member and the lower shield in Figure 5, may, if desired, be made integral with the sealing member rather than with the lower shield as shown. Such modifications may be made without departing from the spirit and scope of our invention as set forth in the appended claims.

What we claim is:

1. In a moisture shield for use with an ignition cable and a spark plug having an insulator and a terminal at the top thereof; a lower sealing member comprising an annular sleeve of rubberlike material, the diameter of the sleeve being reduced at the lower portion thereof for closely engaging the insulator, the sleeve having a top Wall with an opening therethrough for reception over the terminal of the plug, a lower shield having the lower portion thereof recessed for the reception of the upper portion of the lower sealing member and having an opening therethrough for reception over the terminal, a stylus threadedly engaged with the terminal and adapted to urge the lower sealing member into contact with the lower shield and the insulator, the top wall of the lower sealing member being curved so as to expand within the recess of the lower shield when secured by the stylus, and an upper shield threadedly engaged with the lower shield and having an opening through the top thereof. the stylus adapted to expand and seal an ignition cable disposed within the said opening.

2. In a moisture shield for use with a spark plug having van insulator and a terminal at the top thereof; a shield having a recess in the bottom thereof and an opening through the center thereof for reception over the terminal of the plug, a lower sealing member comprising an annular sleeve of rubber-like material, 'the diameter of the-lower portion thereof being reduced to closely engage the insulator, the lower sealing member having a concave upper wall and an opening through the said wall for reception over the terminal, a stylus threadedly engaged on the terminal and adapted to expand and seal the lower sealing member within the recess of the shield, and means providing an enclosure for the stylus.

3. In a moisture shield for use with a spark plug having an insulator and a terminal at the top thereof; a shield having a recess in the bottom thereof and an opening therethrough for reception over the terminal, an annular sleevelike sealing member having an -upper wall receivable within the recess of the shield and having its lower portion constricted to closely engage and provide a seal with the insulator, the upper wall of the sealing member having an opening therethrough for reception over the terminal and being generally cupped in shape, and a stylus adapted to be threadedly engaged with the terminal above the shield and to force the shield downwardly, the cupped upper wall of the sealing member adapted, when forced downwardly, to flatten out and seal within the recess and to further constrict the lower, constricted portion of the sealing member.

4. In a moisture shield for use with a spark plug having an upper terminal and an insulator; a lower shield recessed on the bottom thereof and having an opening through the top thereof adapted to be received over the terminal, the recess in the lower shield having a side wall extending generally vertical for at least a portion of its height, and a sealing member of a rubber-like material disposed generally between the lower shield and the insulator, the sealing member having a top portion thereof adapted to be expanded within the recess of the shield so as to seal against the vertical Wall thereof, the sealing member having a sleeve-like wall extending downwardly from the top portion thereof and inwardly to provide a seal with the insulator.

5. In a moisture shield for use with a spark plug having an insulator 'and an upper terminal; a lower shield having an opening therethrough for reception over the terminal, a flexible, rubberlike sealing member having a cupped top portion disposed between the lower shield and the insulator, the sealing member also having depending and inwardly converging, sleeve-like side wall portions, the lower edges thereof being adapted to be urged into a rm sealing contact with the insulator by downward pressure of the lower shield upon the cupped sealing member, and a nut threadedly received on the terminal to force the lower shield downwardly.

6. In a moisture shield for use with an ignition cable and a spark plug having an insulator and a terminal at the top thereof; means providing Aan electrical connection between the terminal and the cable, means, including a lower shield, providing a moisture-proof enclosure for the cable and terminal, and means providing a moisture-proof seal between the lower shield and the insulator .comprising a exible rubber-like sealing member having a top wall with an opening therethrough adapted to be received over the terminal and below the lower shield, asleeve-like wall depending from the top wall and converging inwardly, at the bottom thereof, toward the `insulator, spacingmeans disposed between the top wall of the sealing member, adjacent the edges thereon-and the lower shield, and a nut engaged on the terminal and adapted to draw the lower shield, the exible sealing means and the insulator together to form a seal therebetween.

'7. In a moisture shield for use with an ignition cable and a spark plug having an insulator and a terminal at the top thereof; means providing an electrical connection between the terminal and the cable, means including a lower body portion, providing a moisture-proof enclosure for the terminal and the end of the cable, means providing a moisture-proof seal between the lower body portion and the insulator comprising a flexible, rubber-like sealing member having a top wall with an opening therethrough adapted to be re- 5 ceived over the terminal and below the lower body portion, a sleeve-like wall depending from the top wall and adapted to contact the insulator to provide a seal therebetween, a nut engaged on the terminal and adapted to urge the lower l0 body portion and the sealing member toward the insulator, and spacing means associated with the lower body portion adapted to urge the outer portions and the sleeve-like wall of the sealing member downwardly and the lower edge thereof inwardly toward the insulator.

8. In a moisture shield for use with an ignition cable and a spark plug having an insulator and a terminal at the top thereof; means providing an electrical connection between the terminal and the cable, means including a lower body portion, providing a moisture-proof enclosure for the terminal, means providing a moisture proof seal between the lower body portion and the insulator comprising a flexible, rubber-like sealing member having 'a top wall with an opening therethrough adapted to be received over the terminal and below the lower body portion, a sleeve-like wall depending from the top wall and adapted to contact the insulator to provide a seal therebetween, 3o and a nut 4engaged on the terminal above the lower body portion.

GEORGE G. BURRELL. ARTHUR L. HULSHIZER.

REFERENCES CITED The -followingreferences are of record in the le of Athis patent:

7UNITED STATES PATENTS

Images