US2705483A - Rotating valve - Google Patents

Description

April 5, 1955 J. J. TEMPLE ROTATING VALVE Filed April 29, 1952 2 Sheets-Sheet l Inventor A ttorneyS m P A M V E G m T m J R April 5, 1955 2 Sheets-Sheet 2 Filed April 29, 1952 FIG.2.

INVENTOR JOSEPH JIM IE5 TEMPLE United States Patent ()flice 2,705,483 Patented Apr. 5, 1955 2,705,483 ROTATING VALVE Joseph J. Temple, Rednal, Birmingham, England, assignor to The Austin Motor Company Limited, Northfield, England Application April 29, 1952, Serial No. 284,886 4 Claims. (Cl. 123-90) This invention relates to poppet valves of overheadvalve internal combustion engines and of the type which are free to rotate in their tubular guides, the chief objects being to make this type of valve safe against valve spring breakage, and to provide an oil seal.

According to the invention, the upper end of the valve stem is fitted with a contact cap for engagement by the valve rocker arm and has a depending cylindrical skirt which closely encircles the end portion of the valve stem beyond the reduced or necked portion thereof which is engaged by the valve cotter, and the valve cotter is in the form of a diametrically split cylindrical cup, the two halves of which are held in embracing engagement with the skirt of the contact cap, and in retaining engagement with the annular recess of the neck in the valve stem, by a spring clip member.

The two halves of the valve cotter are made so that they abut each other, thus closing the gap which usually exists between the valve cotter halves and thereby forming an oil seal.

The split cylindrical cup constituting the valve cotter is housed in an accommodating counterbore in the usual valve spring collar, and the axial dimension of the valve cap skirt and the amount by which it is normally overlapped by the embracing wall of the cotter is somewhat greater than the axial clearance afforded by the necked portion of the valve stem, the arrangement being such that even though the valve spring breaks and the valve falls, or the valve should stick or be held off its seat for any reason, the cap will not come off the valve stem because the cotter will remain embraced upon the cap and in engagement with the neck in the valve stem even though the valve spring collar falls down the valve stem and disengages said cotter. I

The invention will now be described in detail with reference to the accompanying drawings, in which:

Fig. l is a side elevation, partly 1n sect1on, of one poppet valve of an overhead-valve engine, and part of the associated valve-operating mechanism.

Fig. 2 is a detail view, to an enlarged scale, of the upper end of the valve shown in Flg. 1.

Fig. 3 is a plan view of Fig. 2.

Referring to Fig. l of the drawings, a poppet valve 10 has its stem 11 slidably and rotatably mounted in a guide sleeve 12 in the cylinder head 13. The valve is operated in well-known manner by means of a rocker arm 14 which is caused to rock by the reciprocating movements of a push rod 15, the latter receiving its motion from the engine cam-shaft (not shown). D

The valve 10 is normally held upon its seat by the valve spring 16, the latter being in compression between a cupped locating washer 17 on the upper surface of the cylinder head 13, and a valve spring collar 18, the force of the spring 16 acting on the collar 18 being passed on to the valve stem 11 through a cotter assembly, indicated generally in Fig. l by the reference numeral 19 and described in detail below.

Referring to Figs. 2 and 3, the valve stem 11 1s provided with an annular recess affording a reduced diameter neck portion 20 near the upper end of the stem. The extreme upper end of the stem 11 is fitted wlth a contact cap 21 for engagement by the valve actuatmg rocker arm 14 (Fig. l), and said cap 21 has a depending cylindrical skirt 22 which closely encircles the end portion 23 of the valve stem beyond the reduced neck portion 20.

The valve cotter is in the form of a diametrically spl t cylindrical cup 24, the two halves of which abut each other and are held in embracing engagement with the skirt 22 of the contact cap by a spring clip 25, and similarly, whilst walls 26 of the cotter encircle the cap skirt 22, the base 27 of the cotter, which is in the form of an inwardly projecting annular flange, is engaged in the recess afforded by the neck portion 20 of the valve stem, and is retained in this location by the clip 25.

It will be noted that there is a slight clearance gap between the end face of the valve stem and the confronting inner face of the cap 21, and thus the valve stem is not prevented from rotating by reason of this cap and cotter assembly mounted upon the end thereof. Furthermore since the halves of the cotter abut each other they provide an oil seal tending to retain lubricant in the cotter and contact cap assembly.

The split cylindrical cup 24 constituting the valve cotter is rotatably housed in a cylindrical counterbore 28 in the valve spring collar 18, and the axial dimension of the contact cap skirt 22 and the amount by which it is normally overlapped by the embracing wall 26 of the cotter 24 is somewhat greater than the axial clearance afforded by the necked portion 20 of the valve stem so that, even though the valve spring 16 breaks and the valve falls, or the valve should stick or be held off its seat for any reason, the cap 21 will not come off the end 23 of the valve stem, because the cotter will remain embraced on the cap skirt 22 and in engagement with the neck 20 in the valve stem, even though the collar 18 leaves the cotter, since the distance the cotter can fall is limited to the clearance in axial direction between the ends of the recess afiorded by the neck portion 20 of the valve stem and the base 27 of the cotter which embraces the said neck 20, which clearance is less than the overlap between the cotter 26 and skirt 22, and any fall of the cotter is therefore insufficient for it to leave the contact cap and neither the cap nor the cotter will fall off the valve stem.

Having fully described my invention, what I claim and desire to secure by Letters Patent is:

1. In an overhead-valve engine, the improvement comprising a freely rotating poppet valve having a stem provided with a cylindrical reduced portion adjacent its upper end, a valve spring surrounding said stem, a valve spring collar for said spring surrounding the upper portion of said stem and having a cylindrical counterbore, a cap having 21 depending cylindrical skirt closely encircling the upper end of said stem, a cylindrical cupshaped valve cotter rotatably mounted in said counterbore and having a wall portion engaging the skirt of said cap and provided with a base engaging said reduced portion, said cotter being diametrically split to provide two halves, and a spring clip engaging said halves and maintaining them in assembled relation with said valve stem and cap.

2. The improvement according to claim 1 wherein the two halves of the valve cotter abut each other.

3. An assembly for mounting at the necked end portion of the stem of a freely rotating poppet valve of an overhead-valve engine, said assembly comprising, a cap having a cylindrical skirt portion closely encircling and enclosing the end of the valve stem beyond the necked portion thereof, a cylindrical cup-shaped cotter enclosing the skirt portion of the cap and having a base engaging the necked end of said stern, said cotter being diametrically split into two halves, and a spring clip for retaining said halves in abutting relationship.

4. An assembly according to claim 3, wherein the skirt of the cap is overlapped by the wall of the cotter an axial distance which is greater than the clearance in an axial direction between the ends of the necked portion and the base of the cotter which engages said necked portion.

References Cited in the file of this patent UNITED STATES PATENTS 1,840,704 Dawson .Jan. 12, 1932 2,040,960 Smith May 19, 1939 2,674,985 Carlin .Apr. 13, 1954 FOREIGN PATENTS 428,998 Great Britain May 22, 1935

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