From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
United States Patent document for a valve-tappet compensator.
| Identifier | ExFiles\Box 19\3\ Scan152 | |
| Date | 11th October 1927 | |
| Patented Oct. 11, 1927. 1,644,840 UNITED STATES PATENT OFFICE. ROYAL LEE, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO LEE ENGINEERING RESEARCH CORPORATION, OF MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN. VALVE-TAPPET COMPENSATOR. Application filed February 25, 1922. Serial No. 539,150. This invention has for its object to provide a compensator for the valve tappets of gas engines whereby the variation in length of the valve stem or valve rod will effect a compensating variation in length of the tappet whereby lost motion will be avoided with its accompanying objectionable features such as the variation of period and timing of the valve opening and the noise and wear of the loose parts. It is a well known fact that, with the usual valve operating mechanism employed in gas engine construction wherein a tappet is engaged by a cam on the cam shaft and is lifted to lift in turn the valve stem or a valve rod connected with a valve stem by means of a rocker arm, more or less play or lost motion is unavoidable and without frequent adjustment, which is sometimes difficult of accomplishment and more difficult to maintain, this play or lost motion increases with a corresponding increase in the noise of operation caused by the hammering of the parts and a loss of efficiency due to a reduced valve opening period and a variation in the timing of the valve opening movement. Too close an adjustment has to be avoided as it will serve to prevent the valve from seating, especially when the parts are lengthened by the expansion due to heat, and it is usual for manufacturers to caution customers to adjust the tappets only when the engine is hot and then allow a clearance or play between the parts. Such play or clearance will then become greater when the engine is cool with a corresponding decrease in efficiency and increase in noise of operation. The present invention provides a tappet capable of self elongation and contraction by hydraulic jack action to maintain the parts in touch and so prevent play or lost motion and still not cause the valve to be held off of its seat. With the above and other objects in view the invention consists in the valve tappet compensator as herein claimed and all equivalents. Referring to the accompanying drawings, in which like characters of reference indicate the same parts in different views, Fig. 1 is a sectional view of a gas engine valve provided with a tappet compensator of this invention; Fig. 2 is an enlarged sectional view of the tappet on a plane at right angles to that of Fig. 1, and Fig. 3 is a sectional view on the line 3-3 of Fig. 1. In these drawings 10 indicates the engine casing having the usual tappet valve 11 with its stem 12 passing through the guide or bushing 13 and forced by a surrounding valve spring 14 in the direction for closing the valve. While, for convenience, that type of valve having its stem directly engaged by the tappet is shown, it will be understood that the invention is equally applicable to the type of valve having a valve rod engaged by the tappet and connected with the valve stem by means of a rocker arm and, throughout the description and claims wherever the valve stem is referred to, it will be understood that the valve rod of such other valves is also meant. The cam 15 on the cam shaft 16 engages the end of a tappet member 17 in the usual manner to force it against the end of the valve stem 12. The tappet member 17 is slidably fitted in a guide bushing 18 in the usual manner, but, instead of merely being provided with adjusting screw and set nut as usual, it has combined with its adjustment features the feature of self-elongation or contraction before mentioned. The tappet member 17 constitutes a cylinder in which is slidably mounted a hollow plunger 19 containing an oil well 20 with a supply of oil. A cross-pin 21 passes through the cylinder 17 and through slots 22 in the walls of the plunger 19 to afford a spring seat without interfering with the sliding movement of the plunger. Adjustably threaded in the end of the plunger is a screw plug 23, which bears on the end of the valve rod, or valve stem as the case may be, and is locked in its adjustment by a set nut 24 thereon bearing on the flanged end of the plunger 19. Bearing on this screw plug 23 and preferably contained within a cavity in its end is a coiled spring 25, which may be centered by a guide pin 26 with one end fitting in a reduced bore of the screw plug 23 and the other end fitting in an opening in the cross pin 21, while a washer 27 surrounding the guide pin and bearing on cross pin 21 forms a seat for the end of the spring. The parts are so designed that the spring tends to lift the plunger 19 as far as will be permitted or until the screw plug 23 engages | ||