US1628017A - Tappet - Google Patents

Description

May 10-, 1927-v WILCOX TAPPET Filed July 21, 1924 m M w Patented May 10, 1927.

UNITED STATES PATENT OFFICE.

MERRILL M. \HIIJCOX OF SAGINAW,

OF SAID MERRILL WIL WILCOX PRODUCTS CORPO MICHIGAN.

A CORPORATION OF TAPPET.

Application filed July 21, 1924. Serial No. 727,338.

This invention relates to tappets and pertains more particularly to certain unprovements in the construct1on and mode of operation of tappets made of cast iron, with 6 disk-like heads or platforms having hardpet; also, by

ened faces to receiye the actuating cams.

impacts of valve- My present improvement has as an object to provide in the platform a means whereby the depth of hardening of the chilled working face is made practically uniform throughout the entire area of the platform.

Further objects are to increase the strength of the platform to withstand long continued percussions of the cam, and do it without materially increasing the the same means weight of the tapto provide a platform construction that assists in more effective lubrication of the tappet stem as it shoots to and from in the bore of the tappet bracket.

With the foregoing and certain other obin view which wil jects my in the specifications 1 appear later in vention comprises the devices described and claimed and the equivalents thereof. In the drawings tical section of a chilled Fig. 1 is a central veriron tappet head made in accordance with my invention.

Fig. 2 1s atop plan view. Fig. 3 1s a central vertical section of a tappet as commonly produced heretofore,

showing faulty distribution of chill.

Fig.

4 is a fragmentary part sectional view of one end of the tappet bracket showing the tappet in its As is clearly shown in tappet head is preferably piece of cast metal such comprises two main parts like platform 1 and the stem 2.

The platform has its working face 3 made raised position.

the drawings the made of a single as cast iron and namely, the diskintegral shank or flat or substantially so and hardened by chilling in the mold.

smooth, preferably by gri Upon the back of and the platform is a reinfo for example, the raised rim 4.

tions which this reinforce of real importance, not manufacture of the tapp operation.

The working face 3 i Its face is made nding.

cast integral with rcing member, as,

The funcment performs are only during the ct, but also in its s made I extremely 1. as indicated in Fig. 1.

Heretofore tappets made of cast iron have usually been formed as shown in Fig. 3, where the de th of chill at the rim of the platform, in icated by C, may be considerably greater than at the middle 0'. The reason for such lack of uniformity in the depth of chill is that the mass of molten metal which forms the lower part of the central stem or shank, where it joins the platform, is much greater than themass at the edge portions of the platform. Consequently the edges of the platform, being thinner and therefore losing their heat more quickly, are chilled to a greater degree. Frequently the smoothing of the face by grinding results in removing so much of the thinner chilled part of the metal at the center of the platform as to expose a relatively soft area in that part, whereas it should be extremely hard. Various expedients have been devised to increase the depth of chill in the central area and make the entire surface uniform in that regard, none of which attempts prior to my present invention have been entirely successful, so far as I am aware. I have found by long experimenting that a simple and inexpensive change in the configuration of the platform itself does entirely overcome the difficulty and makes a stronger platformto resist impacts of the cam in the direction of the arrow, Fig. 3. My new construction also assists in improving the lubrication of the shank 2 in its bearing 5, as indicated in Fig. 4. i

I reduce the central mass of metal by eliminating the crowned back of the customary platform, shown in Fig. 3, and extend the shank 2 down to the flat top of the platform 1., as shown in Fig. 1. The reinforcing rim 4 or its equivalent supplies a suflicienl body of molten metal at the edge of the platform to prevent its too rapid chilling. The reduction of the mass of molten metal at the middle as above described, together with the increase of the mass of molten metal around the periphery of rim 4 has the effect of establishing the depth of chill at the middle area of the platform and beneath the rim so that throughout the entire area of the working faces practically uniform depth is secured.

The rim 4 also acts as an oil collector which effectively splashes the oil over the rubloinp surfaces of the tappet stem, thereby greatly increasing the ctfectiveness of lubrication of the stem in its bracket bearing 5.

Rim 4 also strengthens the tappet platform to resist impacts of the cam, since the rim serves as a reinforcing band or rib for the back of the platform. It has been found in practice that as compared with previous constructions such as in Fig. 3, the strength to resist impacts against the face of the platform is fully fifty per cent greater in my improved construction, largely due to the more uniform depth of chill made possible by the means herein set forth.

Having thus described my invention what I claim and desire to secure by Letters Pet ent is:

In a, tappet having a shank and a platform cast integral and having the working face of said platform hardened by chilling, a raised reinforcing member cast integral with the platform.

In testimony whereof, I aflix my signature.

MERRILL M. WILCOX.

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