Dec. 3; 1946. w. D. APPEL 2,411,844 ' POPPET VALVE AND GUIDE ASSEMBLY Filed Sept. 16, 1944 ‘ I (7/0/06) . 1 ATTORNEE} ~ Patented Dec. 3, 1946 2,411,844 , UNITED 1 STATES PATENT ~ o1=1=1cs I POPPET vanvnzliuNiiaéiimn ASSEMBLY Walter B. Appel, Orchard Lake, Mich., assignor to General Motors Corporation, Detroit, Mich” ’ I a corporation of Delaware Application September 16, 1944, Serial No. 554,355 3 Claims. (Cl. 123-188) 2 The use of high octane leaded fuel in internal combustion engines has created a problem which . this invention aim-s to solve. The problem arises from the very considerable deposits of lead prod ucts on and in the vicinity of the exhaust poppet valves. These valves are opened positively by cam action but close under the influence of springs. The deposit frequently causes the valve . sults may be had from the use of a counter bored guide this invention makes use of a guide with a uniform bore through which slides a two dimension stem. Among the reasons‘ for select ing the second of these expedients are the fol lowing. The length of annular chamber is con stant when one counterbores the guide whereas with the two dimension stem the guiding portion of the guide increases in length as the valve ~ stems to become so stuck in the valve guides that opens. Also there is no provision for- removing ' the springs cannot overcome the resistance and 10 ..the deposit on the inner wall of the counter close the valves. Thereupon the combustion chamber gases pass around the valve heads, burn bored guide.v On the contrary, the shoulder be tween the two parts of the two dimension stem the heads and stems and soon the valves must scrapes the deposit from the walls of the guide be replaced. In the ‘case of lower octane fuels due to the positive action of the cam. There is 15 similar but lessserious sticking occurs and in another and very important reason for selecting such cases the difficulty has been to some extent the second of the two expedients. The hot gases lessened'by the use of counterbored guides or from around the valve head build up deposits reduced valve stem diameters within the ‘ends along the stem. . Near the head the more intense ' of the guides. . heat burns these to a kind of film but a, little way The present invention has taken cognizance of 20 down the stem, where the heat is somewhat less, these prior expedients adopted to overcome the there is found a bulbous deposit of some appre- ' effects of carbon deposits from relatively low ciable size. This bulbous deposit, if it gets within octane fuels but it has been found that a mere the counterbore of a guide necessitates an other-. unscienti?cally counterbored guide or a two di wise needlessly large counterbore to prevent 25 ameter stem is not enough to solve the present sticking. With a reduced dimensioned stem hav problem. ' . ing less heat conducting metal the critically» hot Very brie?y stated, the problem has’been solved region is nearer the valve head and hence the by resort to a. two dimension valve stem movable bulbous region at the lower end of the critically in a'valve guide having‘ a bore of uniform diam hot region is further from the end of_ the guide. eter, the partsbeing so dimensioned relative to 30 Since it is‘ nearer the head it is well above the‘ the position of the valve head and its seat and end of the guide and ‘does not cause sticking be the stroke of the cam that the shoulder between cause of contact with the guide. A deposit does the parts of the stem shall always be within the collect on the end of the guide, and just within guide and shall approach but not reach the end the end. Therefore the shoulder which is within of the guide as the valve opens. The best re 35 the guide should be so located that, invalve posi sults also require that the radial dimension of tion, it will not contact this deposit. As a mat the annular space between the reduced dimen 'ter of fact the deposit at the guide opening is sion part of the stem and the wall of the guide of use in that it partly closes the annular space shall be such as to permit the collection of a within the guide and around the stem thus seal moderate coating of lead deposit on the stem ing off this space to such an extent as to prevent but that it shall not be so large as to permit a the lead deposits being carried into the space turbulence of gas within the space and conse by the turbulent gases outside. vThere are there quently the‘ carrying of much of the lead deposit fore many reasons for reducing the stem diam into this chamber. The axial dimension should eter rather than counterboring the guide. The not be extended unduly else the stem will not be 45 experiments have shown that very good results properly guided and the valve will not seatas it are obtained with a valve having a 13-32 inch should. 7 stem reduced to 11-32 inch from the valve head The structure which is believed to bethe best for a distance of about 1% in. the shoulder being to carry out the inventive idea is shown on the accompanying drawing, in which: A ' Fig. 1 is a view in elevation of a conventional valve assembly. Figs. 2‘ and 3 are similar views of my new as - 50 always in the guide and the movement being such that, when the valve. is opened by the cam, the shoulder shall be about ya in. from the end of the guide. This will avoid the danger of the large diameter part» sticking to the deposit just - sembly with the valve in two different positions. While with certain valve dimensions good re 55 within the guide opening. I1’, too; the radial 2,411,844 dimension of the annular'space is between 1752 and 3/;4 in., the space has been found to be su?i cient to accommodate the slight collection. of deposit on the stem which will occur in spite of the nearly ‘closed annular space. As explained above, any deposit on the inner wall of the guide except that adjacent the opening beyond the ‘_ limit of outward movement of the shoulder on the stem is scraped off by the shoulder. ‘ Fig. 2 toward the open end of the guide and scrapes on.’ any deposit which may form on the wall of the guide. However, as shown by Fig. 3, when the valve reaches its open position the shoulder is still a little Way from the end vof the guide and does not engage and stick to the deposit I5 which forms at the end of and extends just a little way into the guide. It will also be It is believed that the invention will be under 10 seen that this deposit l5 partially closes the an nular chamber at the end of the guide so that stood from the description above. The drawing the turbulence outside may not extend thereinto serves to illustrate it. On the drawing, the old and carry an undue quantity of carbon or lead type of valve assembly is shown by Fig. 1. Here .. products into the chamber. the valve guide 5 has a uniform bore and the I claim: . _ ' valve stem.'l is also of uniform diameter. The , valve head 9 is showniseated. As explained above, the tendency to collect a deposit on the stem adjacent the end of the guide is indicated by a bulbous formation marked I I (exaggerated). It will be readily seen that the deposit may cause the valve to stick at the end of the guide so that the releasing spring may be unable to break it away. Fig. 2 shows the same valve guide 5 but my improved valve with its stem 1' reduced in diameter as at [3 from the head to a point 25 marked a which is well within the guide when the valve is seated. Also the reduced diameter of the valve stem 1' has ‘caused the bulb II’ to form further from the end of the guide than before, so that it cannot cause sticking. The .30 shoulder at a moves from the position shown by v 1. A valve and guide assembly, said valve hav ingan integral stem with parts of two different diameters forming a shoulder therebetween, the parts being so, proportioned that the shoulder is always within the guide and that the shoulder approaches but does not reach the end of the guide- on the valve opening movement. 2. The invention de?ned by claim 1, the dif ference in diameter being such as to permit only a slight deposit within the space around the stem within theguide. " " ‘ 3. The invention de?ned by claim 1, the open ing movement of the valve carrying the shoulder to a limit at. about one-eighth of an inch from the end of the guide. WALTER, D. APPEL.