US2259905A - Valve tappet - Google Patents

Description

Oct. 21, 1941.` f v. l. MoNcRlEr-'F 1 2,259,905

VALVE TAPPET I lFil-ed Marchl, 1940 2 Sheets-Sheel 1 INVENTOR ATTORNEY Oct. 21, 1941.

v. l. MoNcRlEF'F VALVE TAPPET v Filed March v15, 1940 INVEN'VTQR .BY f ve/@QM ATTORNEY Patented on. 21, 1941 UNI-Tao STATE s PATENT oil-FICE Vcon I. Moncrieff, West Hartford, Conn., assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware AApplication March 15, 1940, Serial No. 324,165

(c1. 12a-9o) This invention relates to improvements in valve operating mechanisms and has particular reference to an improved valve tappet including hyy draulic means for adjusting the operating mechanism to eliminate clearance between the diiferentv elements thereof. i y

An object of the invention resides in the provision of an improved hydraulic adjusting mechanismfor a valve tappet in which the valve operating forces transmitted through the tappet are not rried by the hydraulic uid used tov adjust the tappet but instead, are transmitted through metal screw threads of relatively' low pitch whereby the action ,of the tappet itself is positive and the hydraulic iluid serves only to adjust the tappet to take up clearance in the valve actuating mechanism.

A further object resides in the provision of an improved valve operating mechanism including an automatic tappet adjusting mechanism which functions to maintain the valve operating mechanism tight at al1 times during operation but which is not capable of itselfy of exerting a force in valve closing position.

` A still further object resides in the provision of an improved hydraulic adjusting device for the operating gear of an engine valve so constructed and' arranged that looseness or clearance in the valve gear 1s gradually compensated during the initial period of engine operation and the adjustment is thereafter continuously -maintained during the operating period rather than making a new adjustment for each operation of the valve gear. Y f

Other objects andl advantages will be morev particularly pointed out hereinafter orgwill become apparent as .the description proceeds.

, In the accompanying drawings, in [which like reference numerals' are used to designate similar parts throughout, there is illustratedv a typical which wouldopen the valve or tend to mainte-imu l the valve openfwhen' the operating mechanism is gine and engine valve operating gear showing the valve gear adjusting mechanism of the invention applied thereto.

Fig. 2 is a. sectional view of a differentlfrag- 'mentary portion of an engine -showing Aan engine valve and the portion of the valve actuating by conventional vconnecting rods or link-rods, not

illustrated. Arotatabl valve cam I6 is retained on the crankcase surrounding or adjacent to the crankshaft Il by suitable means suchas the bolt I8, ring 20 and spacer 22 and is driven from the crankshaft by suitable means vincluding the gear teeth 2l. VIn a radial type of internal combustion engine, such as .that illustrated, the-valve cam member' i8 is in the form of a ring supported by abearing 26 on a crankcase offset and ceivesthe ball end of the (push rod 42. TheV engine valve andvalv'e.l actuating mechanism and i an actuating mechanism adjusting device for substantially eliminating clearance 'between the' various elements of the valve activatingy mechanism during engineoperatio". The'drawlss.

is provided with two` rows of valve operating cams sis/.indicated at 28 and Il.l A tappet, generalLvy indicated at 32, is slidably mounted in a tappet .guide ll secured in the crankcase III and 'is provided at its lower or inner end ,witha roller ,3B which rolls on the cams of the row A28 and at its upper end with a socket member I8 which repush rod 42 extends along the cylinder I2 and'at its upper end'is provided witha ball element M,

l cularly illustrated in Fig. 2, which is receivedin a socket in one end :of a valve rocker arm l0 rotatably mounted intermediate its length on the anti-friction bearingv secured in' the kerbox Il and carrying at its opposite'end an adjustable socket l! which .receives'a ball 54 .bearing on the-upper end of the valve stem it.

- Thefvaiv'e stem!! hassecured upon the-upper however, are forthe purpose oi! illustration only l and are-not to be taken' as 4limiting the inventionsince itwill be 'apparent to. those skilled in the art that various changes in the illustrated .'constructionvmay vbe resorted to withoutin any way exceeding'the scope of the invention.

'the Vaccomllvani'ing drawings, Fig. 1 is a setional view of a fragmentary portion of an Ien- 5l or outer end'rthereof a valve spring retainer" I8 which cooperates with the .valve springs Si and I2 .to move the valve stem through the guide M to v bring the head'- inizi-.gclodng relation with the valve seat Il. The rocker arm Ill under actuation 4ofthe` pushl rodf acts to compress'the springs and' l2 and move' the head -ll ,away

'fromtheseat to open the valve, in s manner well known to the art. While only one valve and valve operating mechanism has been illustrated,

it is well known that the conventional engine has a plurality of cylinders, two or more valves for veach cylinder and an operating gear for each parent" that whenever the roller 36 rides up on one of the cams in the row 28, as is particularly illustrated in Fig. 1, the tappet 82 will be moved upwardly or outwardly in the guide :it and will move the push rod d2 to rotate the rocker arm t8 about the bearing i8 and move the plug 52 and ball 54 in a direction to force the valve stem downwardly or inwardly through the guide Sli to compress the springs 80 and 82 and open the valve, and when the roller rides down ofi of the cam the springs 80 and 62 will close the valve and force the push rod and valve tappet downwardly or inwardly to ride on the inter-cam track ofthe cam member it, in the position particularly illustrated in Fig. 3. l

As the engine operating temperature is considerably above the temperature of the atmosphere and as the metal elements of the valve operating gear have a natural coefdcient of heat expansion and the length of the cylinders also changes because of the heat expansion coelcient of the cylinder material and the change of temperature from inoperative to engine operating conditions` and as it is not always possible to maintain the valve operating mechanism in exact adjustment, there is nearly always a certain amount of clearance or looseness in the valve operating mechanism which will permit a certain amount of movement of the tappet 32 before the `valve begins tovopen. This clearance may increase or decrease as the engine warms up, the

tendency in the type of engine illustrated being for the clearance to increase with temperature until it becomes relatively large, in vsome cases of the order of 0.060 of an inch. This large clearance occasionsan objectionable amount of noise and cdnsderable unnecessary wear of the valve parts and leakage of lubricating uid when the valve `actuating mechanism is supplied with pressure lubrication from the engine. A large number ci devices have been suggested for autothe tappet guide. The tappet is provided with a transverse channel 16 which connects with a.

longitudinal channel 18 which leads the oil past the tappet adjusting mechanism to a channel provided in the inner ball end 40 from which the oil ows through the hollow push rod and through channels in the upper or outer ball endv 48 and in the rocker arm 48 to lubricate the valve operating mechanism all as particularly set forth in' United States Patent Number 2,123,681, issued July 12, 1938,' to Andrew V. D. Willgoos for Internal combustion engine-rocker arm lubrication. As'is particularly shown inFig. 1 and as is particularly set forth in the patent above referred to, the ports 'I4 and 16 register only when the roller 36 is moved outwardly by one of the cams 28 so that the valve actuating mechanism and its ends are sealed by the walls of the tappet guide 34 and oil .under pressure is supplied from the port 14 throughA the channel 8| and con-'- necting channel V82 to a longitudinal well or bore 84 provided in the tappet at the bottom of the larger bore 88 which extends to the upper end of` the tappet. A check ball 88 is urged by a compression spring 90 to seat in the inner end of thevbore 84 to close the channel 82 and prevent oil from owing out of the bore through the channel. A reciprocable plunger 92 has a/hollow matically eliminating this clearanceduring engine operation but so far as applicant is aware these .various prior art devices are subject to certain serious defects. and no one of them has,

up to the present, been put to any important commercial use.

It is to be understood that, while the improved automatic. adjusting mechanism for the valve operating gear' of an engine has been shown as applied to a radial type of engine such asis or'- dinarily used for the propulsion of aircraft, this actuating gear of any type of engine us/ing valves.

actuated by slidable cam operated tappets.

In the improved construction, oil under pressure from the engine lubricating system is ledv lower end portion. 94 reciprocable in the bore 84 and a reduced upper end portion 98 passing through an aperture provided in the socket 88 and into contact with the ball end 40. I'he socket 38 is screw threaded into the open end of the bore 86, as indicated at 98, in such a manner that rotation of the socket relative to' the tappet at |02 and |04. The end splines |02 are arranged parallel to the axis of the tubular member and cooperate with internal splines |08 provided inl the hollow'inner portion of the socket 38. -The splines |04v are spiral in form that is, arranged at an angle to the axis of the tubular member,

. and cooperate with corresponding spiral splines Varrangement is for convenience in illustration .The screw threads 98 and the splines' |02 and through the manifold 10 to the interiors of the various tappet guides B4 by means of drilled screw plugs 'l2 which provide'ports 14 leading from |08 provided in the interior of the tappet 32 in termediate the length of the bore 86.A The lower portion of the member |00y has a substantially fluid tight t with the lower endA of'the bore 86.

|04 are so designed that an upward movement ofthe member |00 in the bore |08 toward the socket 38 will rotate the socket in a direction to screw it outwardly relative to theI tappet on the threads 98, and a movement of the member loo toward the bottom or the boro as will move the socket 38`inwardly relative vto the tappet. While the socket may be moved' inwardly and outwardly relative to the tappet it is to be noted that the force between the socket and the tappet for opening the valve is carried by the screw thread 98 and not by the lubricating oil supplied through the channel 80. A compression spring 'disposed between an annular shoulder ||-2 on the plunger 92 and an internal flange III at the inner end of the member '|00 resliently urges the plunger 92 outwardly 'with respect to" the member |00 and the tappet and maintains the upper 'end of the plunger in contact. with the adjacent., surface of tl ball end 40. The hollow inner end 94 of the plunger 92 is provided with a valve seat surrounding an aperture H6 closed from the inside by a check ball ||8 urged into seating relation over the aperture bya coil spring |20. Ports |22 lead from the interior of the hollow end 94 into the space in the bottom of ber |00.

The operationof the device is 'substantially as aasaoos the innerportion of the' socket 38, from where it iiows through a clearance provided between thev plunger end 96 and the aperture in the socket 38 to the end of thechannel 80 in theball end l0.

the-purpose of disclosing the invention has been While a suitable mechanical embodiment for hereinabove described and illustrated i'n the accompanying drawings, it is to be understood that the invention is not limited'to the particular constructionso illustrated and describedbut that such changes in the size, shape and arrangements of thevarious parts may be resorted to as come 1 the bore 86 below the end of the tubular memwhen the valve is closed and the valve is closed and the roller 38 is between cams, as illustrated in Fig. 3, the plunger 92 will be forced upwardly by thespring H0 lifting the ball end Il!v 'out of contact with the socket 38, it being assumed that the member |00 is in a predetermined limiting Ainward position. If the engineis operating or f begins to operate, as the roller 86 rides up on a cam 28 the tappet 32 will be forced upwardly. As the strength of the spring ||0 is not sufficient to compress the valve springs 90 and 02, the

plunger 92 will be forced inwardly until the ball the surface of the end comes in contact with socket 38. As the plunger is forced inwardly oil from the space in the wall 94 below the plunger the interior of the hollow end 9| forcing some oil contained in this 'hollow end out through the gradually pumping oil from the bore 94 into the space below the member |00I until the socket 38 has been `rotated outwardly on the screw thread 98a suicient amount to take up vthe clearance and discontinue the pumping action of the plunger. The oil pumped from thewell 84 by the plunger 92 is replenished each time the channel 80 comes'into registry with the port 14 in 'the relative position of the parts illustrated lin Fig. 3. As long as the engine isoperating there i will be a constant vsupply of uid available to .m intain the member |00 in the proper position' to eliminate clearance in the valve actuating mechanism but as soon as the engine stops this iiuid will tend to gradually leak from the mechanism and thespring ||0 will then force the member |00 inwardly of the bore 88 to its limiting inward position from which position it will automatically start to move to eliminate clearance 'in valve actuating mechanism vwhen the engine is again put into operation.

The oil for lubricating the'valve mechanism flows from the channel 19 into the interior of the bore 86 beyond the portion which provides element.

' will be forced through the aperture H0 and into valve to apply fluid pressure to said .abutment within the scope of the subjoined claims.

Having now described the invention so that y others skilled in the art may clearly understand the same, what it isv desired to secure by Letters Patent is-as follows:

`l. An adjustable valve tappet comprising' a cam actuated reciprocable portion, an adjustable abutment screw threaded into one end oi' said reciprocable portion on low pitch irreversible screw threads, iiuid pressure actuated means for rotating said abutment relative to said reciprocable portion to adjust the length of said tappet; and means operative only when the lengthof said tappet is insuillcient for applying fluid pres sure to said pressure actuated means.

2. An adjustable valve Atappet comprising, a hollow reciprocable member, an adjustable abutment screw threaded into one end of said reciprocable member, a fluid pressure actuated element foradjusting said abutment relative to said reciprocable member, and a pump carried by said reciprocable member `and having `an actuating portion extending through said abutment for applying uid pressure to said pressure actuated 3. In an engine valve actuating mechanism including a cam, and a ltappet movable by said cam, means for automatically eliminating clearance between said tappet and the valve comprising, an abutment adjustably threaded into said tappet, a iiuid pressure device carried by said tappet for rotating said abutment to adjust the'y valve to apply fluid pressure to said abutmentl adjusting member. v

4. In an engine valve actuating mechanismincluding a cam, atappet movable by said cam,

and a push rod movable by said tappet, means for automatically eliminating clearance between said tappet and said valve comprising, an abutment adjustably threaded into said tappet, a

fluid pressure actuated member for rotating said abutment to adjust 'the same relative to said tappet, and a pump operative by relative movev ment of said tappet andV said push rod when clearance exists between vsaid tappet and said adjusting member.

5. In avalve actuating mechanism including a cam, a tappet actuated by said cam, and means for transferring the movements of said tappet to said valve adjustable relative to said tappet to change the effective length of said tappet, means for `adjusting' the length of said tappet between said v`cam and said movement transferring meansI comprising, fluid pressure actuated means operatively connected with said movement transthe fluid tight seal with the member |00 and then flows through the spline connections |00 and |02 to :ill the member |00 and the hollowinterior of ferring means for changing the effective length of said tappet, and a pump operative only -when the length of said tappet is insufficient for applying fluid pressure to said pressure actuated means. A

6. In a valve actuating mechanism including a cam, a tappet actuated'by said cam, means for transferring the movements of said tappet to said.

valve, and means for supplying lubricating oil toA said tappet, iluid pressure actuated means for adjusting the -eie'ctive length of said tappet, and

' a pump connected with said lubricating oil suppy only at predetermined positions of said tappet operative only when the effective length of said tappet is insufficient to apply iuid pressure to said pressure actuated means.

7. In a valve actuating mechanism including a cam, a tappet actuated by said cam, means for transferring the movements of said tappet to said valve, and means for supplying lubricating oil to said tappet, iuid pressure actuated means for adjusting the effective length of said tappet, and a pump connected .with said lubricating oil supply only at predetermined positions of said tappet operative only when the eiective length of said eratively connected with said valve, a tappet, and

a cam for moving said tappet, `means fonautomatically adjusting the ,effective length of said tappet to'eliminate clearance in said valve gear comprising, an abutment for said push rod screw threaded into the outer end of said tappet, a uid pressure actuated element for turning said abutment on said screw 'threads to eliminate.' clear# ance in said valve gear, and a uid pump for applying uid pressure to saidpressure actuated element said pump'having an actuating plunger extending. through said abutment into contact with said push rod and a spring acting on said stem to urge t said push rod away Vfrom said tappet said spring having less strength than said valve spring whereby said pump will be operated during operation of said valve lgear .with c1ear ance between the parts thereof.

9 In a valve actuating mechanism including a cam, a tappet actuated by said cam, and means including a push rod for transferring the movements of said tappet to said valve, means for adjusting the length of said tappet between said cam and said push `rod comprising, fluid presload, and a pump operated by relative movement between said tappet and said push rod for applying uid pressure to said pressure actuated means. a r I VEQN I. MONCRIEFF.

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