June 21, 1955 A. W. RCKENEBACH 2,711,161 HYDRAULIC Filed Sept. 16, 1952 Sheets-Sheet l

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INVENTOR AUGUST W. RICKENBACH

ATTORAVEYS June 21, 1955 A. W. RICKENEBACH 2,711,161 2 Sheets-Sheet 2

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INVENTOR. AUGUST W. RICKENBACH.

AT TORNEYs. 2,711,16 United States Patent Office Faterated Jurae 25, 1955 2 way, slight spurious movements delivered to the tappet are not transferred to the valves. - 2,711,161 In view of the foregoing, it will be appreciated that it is an object of the present invention to provide an im HYDRAULIC TAPPET 3 proved hydraulic tappet. August W. Rickenbach, Williamsport, Pa., assignor to Another object of the invention is to provide means Avco Manufacturing Corporation, Cincinnati, Ohio, a for improving hydraulic tappet operation which can be corporation of Delaware readily added to existing at very little cost. It is also an object of the invention to provide a hy Application September 16, 1952, Serial No. 309,787 draulic tappet which will prevent the transmission of very 1 Ciaim. (Cl. 123-90) small movements to the valve linkage. Stated otherwise, it is an object of the invention to provide a hydraulic tappet, the components of which must undergo a slight The present invention relates to a component of an relative movement before the tappet will be effective to internal combustion engine, and, more specifically, to an transfer motion from a to an associated valve. improved hydraulic tappet for use in an internal combus A still further object of the invention is the provision tion engine having valves for controlling the or of an improvement for a hydraulic tappet which will exhaust of gases from a of the engine. significantly improve its performance without jeopardizing A problem frequently encountered in the construction any of its well-known desirable characteristics. and operation of internal combustion engines is that of Another object of the invention is the provision of a maintaining proper adjustment of the mechanical elements hydraulic tappet which will preclude the transmission of which actuate the inlet and exhaust valves. This problem spurious camshaft motions regardless of the position is aggravated by thermal expansion and contraction of assumed by the tappet while in use. This is a particularly the engine which make it difficult to maintain adjust important feature of the invention since hydraulic tap ment of the valve actuating elements. As is well-known 5 pets are widely used in the aircraft field in which engines to those skilled in this art, proper adjustment is im commonly assume a wide variety of positions while in portant, for it assures that the valves will seat fully and Se. - - prevents the actuating elements or valve linkage from The novel features that are considered characteristic holding the valves in an open position in which burning of the invention are set forth in the appended claim; the of the valves would occur. invention itself, however, both as to its organization and Because of the importance of proper adjustment, hy method of operation, together with additional objects. draulic tappets are often incorporated in engines. Basi and advantages thereof, will best be understood from cally, a hydraulic tappet incorporates a and cylin the following description of a specific embodiment when der assembly which is expanded by high pressure oil, read in conjunction with the accompanying drawings, in supplied by the engine, to take up the clearance within the which: valve linkage. The areas within the tappet assembly on Figure 1 is an enlarged longitudinal sectional view of a which the oil acts and the pressure of the oil used, are hydraulic tappet incorporating a spring washer in keep such that the tappet itself cannot open the valves; thus ing with the novel teaching of the present invention; proper adjustment is maintained and the valves are not Figure 2 is a greatly enlarged cross sectional view of prevented from seating properly. Hydraulic tappets, the spring washer used within the tappet assembly; and therefore, make it possible to avoid many of the difficul Figure 3 is a longitudinal sectional view through one ties previously encountered. cylinder and its associated valve actuating system of an On the other hand, hydraulic tappets are not entirely internal combustion engine, certain parts of the engine satisfactory since their inherent operation is such that all being broken away to facilitate a description of its in clearance is eliminated from the valve linkage. This be ternal construction. ?• ing the case, even slight spurious movements of the As illustrated in Figure 3, a hydraulic tappet, gener associated shaft are transmitted through the linkage ally designated 1, is slidably positioned in the to the valves, causing the valves to open erratically and 2 of an internal combustion engine, generally designated leading to backfiring and rough running of the engine. ; 3. Cylinder 4 of the engine is bolted to the crankcase, The source of such spurious movements is not entirely the cylinder including a 5 in which is formed clear at this time, but it is thought that such movements a rocker box 6 covered by rocker box cover 7. Hy might result from whipping, i.e., flexing of the can shaft, draulic tappet 1 cooperates with a valve linkage, gen or shifting of the cam shaft because of excessive cam erally designated 8, the valve linkage including rocker shaft bearing clearances. On the other hand, it is thought arm 9, pivoted as at 10, within rocker box 6. The possible that the tappet may tend to bounce on its as 55 transfers motion to valve 11 which, for con sociated cam, particularly during high speed operation. venience of illustration, is an inlet valve for admitting a Regardless of the source of spurious motions, it is a fact combustible charge to cylinder 4. As is conventional, that difficulty has been encountered in operation of en an inlet pipe 12 is connected to intake port 3 from gines having hydraulic tappets, the difficulty manifesting which the combustible charge is admitted to the cylin itself in rough running of the engine, backfiring, and 30 der by valve 11. : generally unsatisfactory performance. The engine is conventional in its provision of a re The present invention eliminates all of these difficulties ciprocating piston 14 connected to a 15 and assures that hydraulic tappets can be used without which, in turn, is rotatably secured to a pin ió concern for any spurious movements delivered to the of 17. A 18 is also provided for tappets. Briefly stated, the present invention comprises a 65 igniting the combustible charge within the cylinder, the spring-type washer disposed between two components of energy resulting from combustion being transferred to the hydraulic tappet through which motion must be trans piston 14 and crankshaft 17. ferred when the cam shaft acts on the tappet to move the While the engine is in operation, cam shaft 9 is con valve linkage. This spring-type washer permits a small tinuously rotated at one-half the rate of crankshaft 17. 70 The cam shaft includes cam 20 positioned for coopera amount of motion between the tappet components before tion with face 21 of the hydraulic tappet. In a con movement is transferred to the valve linkage and, in this ventional manner cam. 20, in the course of its rotation, 2,711,161. 3 4 imparts a periodic reciprocating movement to the hy turn the valve 1i to a fully seated position and check valve draulic tappet which, in turn, transfers this motion to 33 again admits oil to the interior of cylinder 27 to expand valve linkage 8 which operates valve 1 through the the length of the tappet and thereby take up any clear rocker arm 9. Valve springs 22 are provided within ance in the system. the rocker box, the springs being engaged with the valve 5 The foregoing description outlines briefly the oper washer 23 which is locked at 24 to the stem of the valve. ation of a conventional hydraulic tappet under optimum The springs act to hold the valve closed against its seat conditions. As has been described, however, such 25 at all times, and, thus, the valve linkage must over optimum conditions do not always prevail and occasional come the load of these springs in addition to the net gas ly very small motions are delivered by the cam shaft to forces acting on the valve before the valve can be forced O the tappet. To prevent such motions from opening the open. - valves at improper times, a spring washer 37 is provided in The particular form of engine used is not of impor an annular space 38 defined by sleeve 26 and cylinder tance to this invention, although the invention has found 27. This spring washer is shown in enlarged view in most widespread use in 4-cycle engines. In a typical Figure 2. It will be noted that the faces of the washer engine of this type, the inlet valve is opened during every 39 and 40 define conical surfaces inclined at an angle to : other revolution of the crankshaft, the inlet valve remain the axis of the washer. This type washer per se is not ing closed during the time that combustion occurs within novel. It is characteristic of this washer that it can be the cylinder and the exhaust gases are expelled there deflected from its normal position shown in Figure 2 into from. It will be appreciated that if the valve lifts off a flexed position in which faces 39 and 40 lie within paral of its seat during the time that combustion is taking place, lel planes perpendicular to the central axis. Defiection a loss of pressure from the cylinder will occur and the of the washer into such a position requires a compressive charge within pipe 12 may be ignited with highly un load; the washer will return to the position of Figure 2 desirable backfiring and danger of fire. whenever released from this load. s ...... It has been observed that in 4-cycle engines incor Inasmuch as cylinder 27 is slidably retained within porating conventional hydraulic tappets rough running sleeve 26, it will be appreciated that washer 37 will be and backfiring is apt to occur. It has been deduced that flattened into its loaded position before motion is trans very slight movements of the cam shaft, in the order of mitted to piston 28. This can be assured by designing the .003 to .005 of an inch, occur, possibly from the flexing washer with a low spring rate. Movements imparted to of the camshaft, or possibly from movement of the cam sleeve 26 must be of greater magnitude than the motion shaft within its bearings. Since the hydraulic tappet, as 30 required to flatten washer 37 before any movement is . will be explained more fully hereinafter, takes up any transferred to piston, 28. This motion, for the hydraulic clearance in the valve linkage, such movements, although tappet illustrated, is in the order of magnitude of .006 small, are transmitted directly to the valves and it is of an inch. Thus, stray movements of .004 of an inch, - thought that these movements cause the faulty engine or less, are not transmitted through the tappet assembly operation encountered. The present invention was de and do not affect in any way the operation of the engine. vised to eliminate this difficulty and has been applied On the other hand, when sizable movements are trans practically to engines with excellent results. ferred to the tappet, as by the normal rotation of the cam The invention is illustrated particularly well in Figure 1 shaft, the washer 37 is first flattened and then the normal in which is shown a hydraulic tappet including an outer lift of the cam is transferred to the valve through the re sleeve 26 slidably retaining a cylinder member 27 within 40 lated linkage system. . . which is slidably disposed a piston 28. An oil port 29 It will be apparent to those skilled in the art that this is provided in the side wall of sleeve 26. Oil under pres is an extremely simple structure to accomplish a highly . sure is supplied to port 29 through a high pressure oil . desirable result, and one which can be readily added to . . channel 30 (see Figure 3), the oil passing into internal conventional hydraulic tappets to improve their operation. volume 3 from which it is supplied through tube 32 to 45 Another thing that will become apparent is that the oper the interior of cylinder 27. The oil flows past a check ation of the improved tappet is by no way influenced by . valve 33, comprising a steel ball 34 which cooperates its position, as is the case in other devices designed to at- ... with a seat 35 formed integrally with tube 32. Under cer tain the same purpose. . . , ." - tain conditions of operation, as will be described, oil pass Inasmuch as the spring washer is mot flexed beyond its - ing through tube 32 lifts ball 34 and enters cylinder. 27 50 elastic limit, it always returns to its unstressed position beneath piston 28. The oil pressure, acting on the piston, shown in Figure 1 when the load imposed by the cam 20 cooperates with a spring 36 in urging piston 28 towards is released. At such time, the spring washer returns to its the right, as viewed in Figure 1. It will be noted that unloaded position and the oil entering the tappet from spring 36 is engaged with cylinder 27 and piston 28. port 29 causes it to take up the clearance in the system in During that part of the engine cycle during which valve a perfectly conventional manner. . . . ' ii should remain closed, oil pressure, entering through 5 3 It will be noted that the spring washer flexes as require port 29 and passing through check valve 33, acts to move to offset the effect of any stray motions imparted to the piston 28 outwardly of the hydraulic tappet thereby taking valve linkage system from any source. On the other hand, up any looseness, or clearance, in the valve linkage, or the washer flattens and acts as a load transferring com between the rocker arm and valve stem. When cam 20, 5) ponent of the tappet during the time that the associated. in the course of its rotation, imparts motion to the tappet valve is being opened in the course of normal operation. during its normal operation, force is transferred through It will be appreciated by those skilled in the art that this ... " the tappet, piston 28 of the tappet assenbly delivering the invention, although simple in construction, is highly novel force to the valve linkage. As a result, the tappet as and represents a very significant advance in the art of tap sembly constitutes a load transferring member momen pet design and one which improves the performance of tarily placed under compression. 65 engines containing hydraulic tappets. The force exerted on piston 23 is opposed by the oil Having described a specific embodiment of my inven trapped within cylinder 27. Compression of the oil forces tion, I claim: ?? .. " ?: ?? , ball 34 of the check valve tightly against its seat. During In a hydraulic tappet for use in an engine which sup the time that this compressive load exists, a slight amount 70 plies a source of high pressure oil for the tappet, the com of leakage occurs between the wall of piston 28 and the bination comprising an outer cylindrical shell, a cylinder interior of cylinder 27, although the leakage is not large slidably disposed within said shell, a piston movably enough to adversely affect the usefulness of the tappet as posed within said cylinder, valve means for admitting Bii - a compression member. After cam 20 advances far under pressure to the interior of said cylinder, said shell . . . enough to relieve the load from the tappet, springs 22 re and said cylinder being formed to define opposed flat an

2,711,16 5 6 nular faces defining an annular space between them, and a conoidal spring-type washer in the annular space main References Cited in the file of this patent taining predetermined clearince between said annular UNITED STATES PATENTS faces, said spring-type washer when deflected coming into 2,074,155 Truesdell ------Mar. 16, 1937 bearing engagement with said annular faces whereby it 2,116,749 Daisley ------May 10, 1938 serves as a compression member between said shell and 2,370,761 Voorhies ------Mar. 6, 1945 said cylinder. 2,468,332 Johnson ------Apr. 26, 19-49 2,595,583 Johnson ------May 6, 1952 2,633,112 Engemann ------Mar. 31, 1953