US1994743A - Valve compensating mechanism - Google Patents

Description

March 19, 1935. B. G. ANDERSON 1,994,743

VALVE COMPENSATING MECHANISM Filed July 1, 1951 2 Sheets-Sheet 1 INVENTOR ATTORN EI YS March 19, 1935. B. e. ANDERSON I 1,994,743

. VALVE COMPENSATING MECHANISM Filed July 1, 1951 2 Sheets-Sheet 2 Q I INVENTOR I ATTORNE 5.

Patented Mar. 19, 1935 UNITED "STATES tearsrrrlca l VALVE coivrrnnsn'rmo Mechanism! Bror G. Anderson, Syracuse, N. Y. Application July 1,1931, Seriali No. 548,176 1 Claim. (01. 1235-90). 1

This invention has for its. object a particularly simple, compact and efiicient valve mechanism for the valves of internal combustion engines by which a sufiicient, but not excessive, tappet clearance is maintained under all temperatures, and which clearance is taken up without tappet noises.

The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed. 1

Indescribing. this invention,-reference is had to the accompanying drawings, in which like characters designate corresponding parts in all the views. V

Figure 1 is an elevation of this-compensating 5 mechanism, the same being shown as applied to an over-head valve mechanism, fragmentary portions of the engine being shown.

Figure 2 is an enlarged, fragmentary view, partly in section, of parts seen in Figure 1.- t

Figure 3 is a sectional view on line 33, Figure 2.

Figure 4 is a sectional view of this valve compensatingmechanism applied to upwardly lifting valves, as the valves of an L-head engine.

Figure 5 is a sectional view on line 5--5, Figurel.v n

It is well known that in internal combustion en gines, the valve tappet clearance, or the clearances in the valve operating :mechanism, vary as 3() theengine heats up and the cylinders elongate,

and that some means is necessaryyor at least highly desirable,'to take up theclearance without tappet noises or with minimum noise.

The inventioncomprises generally a compena sating mechanism including a lever interposed between the driving member or :push rodand the driven member which operates the valve, the lever being pivoted to one of saidmembers, and having an arm for thrusting against the other with a lost motionconnection between the lever and the member to'which it is pivoted, the lost motion connection being located'nearer the axis of the lever than the point on said arm where the thrust of thedriving member is received.

More specifically, this invention comprises a compensating mechanism preferably having a wedging or rolling in action, that is, an action in a lateral direction or a direction at an angle to the direction of movement of the members 8 and 50 5, for taking up the clearance underall conditions, the wedge receiving the thrust of the driving member or lift'rod of the valve mechanism and first serving to take up the clearance with a wedging action, and a spring for acting in oppo- 55. sition to the driving member or push rod to return the wedge to its normal position and maintain the normal clearance when the valve closes, the wedge being operated to take up the clearance during the opening operation of the valvemecha- 'nism. More specifically, the wedge means com- ,5

prises a wedge or cam having a movement about anaxis;

In Figures 1 and 2, I have shown my invention as applied to an over-head valve mechanism.

1 designates the valve, and2 the valve seat of 19 a cylinder. 3 is the valve stem; and 4 the springs which close the valve head against its seat. 5,is a rocker lever, or a driven member of the valve mechanism, this being pivoted at 6 between its ends toa suitable support 7 mounted in any 15, suitable manner on the head of the engine cylinder. p Q

8 designates the driving member or lift rod of the valve, mechanism, this being guided ina suitable bushing 9 inthe top wall of the crank case 20 10 of the engine, and coacting at its lower end witha cam ll on the cam shaft of the engine. The driving member or push rod 8 thrusts toward the rocker arm lever 5, but the motion is transmitted to said lever through the compensating mechanism. i i

The take-up mechanism comprises a lever 12 pivoted to a depending end portion '13 of the lever 5 and having a surface 14 ooacting with the surface 15 on the lever 5, the lever 12 having an'arm extending laterally relatively to the push rod and provided with means for coacting with the end of the push'rod to receive the thrust therefrom. The take-up means further includes a spring 16 interposed between the lever 12 and the lever 5. One of the surfaces 14, 15 is an eccentric or cam sur face, and the other is a follower surface. Preferably, the surface 14 on the lever is the eccentric or cam and also the follower surface 15, as here shown, extends around or embraces the cam surface to a considerable extent, although it may be of relatively small area as a little more than a point. e I 1 As seen in FigureZ, there is a clearance at 17 between the cam surface 14 and the cam surface 15. The spring '16 is 'of sufiicient weight or strengthto normally hold or press the lever 12 against the end of the push rod 8, but is a relatively light spring compared with the valve springs 4. r Y p In operation, the parts are normally in the position shown in Figure 2. As the cam 11 lifts the push rod 8, as shown in Figure 2, the lever.12 is moved upwardly about its axis against the spring 16, and in so doing, rolls or moves thecam so that its eccentric portion first takes up the clearance 17 and then the additional thrust of the push'rod'8' is transferred to the lever 5 through the solid connection formed between the compensating lever 12 and the rocker arm lever 5, this movement opening the valve head 1.

When the cam 11 clears, or moves out of engagement with the push rod 8, the springs 4 react to close the valve, and the spring 16 reacts during the retrograde movement of the push rod 8 and holds the engaging means on the lever 12 against the end of the push rod, and in so doing, moves the lever 12 downwardly about its pivot to again provide the clearance at 17. This clearance 1'7 will vary slightly due to the temperature of the engine, and changes and conditions ordinarily brought about by expansion and contraction of the engine cylinder under working conditions. The compensating lever 12 has an eccentricity for the reduction of the valve tappet clearance at a ratio of approximately 10 to 1. Assume that the clearance is .010 of an inch before the compensating spring is inserted, and that the compensating lever 12 has taken up the clearance at 17, then the compensating spring is inserted and the spring adjusted. The valve tappet clearance is thenreduced to nothing, due to the pressure of the com pensating spring, which at all times keeps the engaging means or lever 12 in contact with the push rod 8, but a clearance is created at '17 and enaccount of the'ratioof 1 to 10 mentioned above, this clearancel? will only be .001 of an inch. .As the valve lifter rod moves upwardly under the action of the cam shaft, the clearance 1'7 decreases to zero. I Owing to the wedge, or eccentric, the taking up of the clearance is gradual as the curves, or convex and concave surfaces, of the cam and the driven member or lever 5 come together to take up the clearance with a sliding movement, instead of with an impact, so that the compensating mechanism has a quiet action.

. The means on the lever 12 for receiving the thrust of the push rod is preferably adjustable, and here shown as a screw 18 threading through the arm 12 with its lower end arranged to engage the upper end of the push rod, a lock nut 19 being provided for holding the screw in its adjusted position. The spring 16 at its lower end encircles the head of the screw 18, and at its upper end thrusts against an abutment 29 threading into the lever 5, this abutment being hollow in order to provide a work hole 21 through which the'screw 18 is accessible.

The compensating lever 12 is here shown as provided with a bifurcated hub or cam mounted on a pin 22 mounted in the depending portion 13 of the lever 5, the portion 13 extending between the bifurcations of the lever 12. The cam surfaces 1.4 are provided on the periphery of the bifurcated hub of the lever 12 and there are two cam surfaces 15 on the lever 5 coacting with the surfaces 14 on the hub of the lever 12. The pivot pin 22 is shown as held in position by snap rings 25 at the ends thereof. Also, the pivot is provided with oil grooves 26 and the hubof the lever 12 and the ad{ jacent portion of the lever 5 provided with communicating oil ducts 27. The oilis supplied in any suitable manner. I

In Figures 4 and 5, this compensating mechanism is shown as applied to a valve mechanism such as are used in L head engines. i

41 designates the valve head, 42 the valve seat, 43 the valve stem, and 44 the valve spring.

45 designates the driven member which instead of being a lever, is a reciprocally movable push rod or plunger guided in any suitable manner in a guide 46. The push rod 45 is-provided with a screw 47 extending axially thereof which thrusts against the endof the valve stem. This screw 47 also serves as an abutment for the compensat ing spring 56. 1 r

48 is the lift rod guided in a suitable bushing 49 in the top wall of the crank case 50 and coacting at its loweriend with thejcam i5lyon the cam.

Shaft. i

52 is the compensating lever pivoted to a laterally extending arm 53 on the driven member or plunger. The cam has an eccentric cam surface 54 coacting with a complemental surface 55 on the arm of the push rod 45.

56 is a compensating spring interposed between the screw 47 and'the armof the compensating lever 52. 58 is an adjusting screw in the arm of the lever 52 and thrusting against the upper end of.

the driving member, or lift rod-48 and'is-provided with a head 71 by which it is adjustable,

J The guide 46 is supportedas shownin Figure 5, by brackets '72- extending-upwardly from the guide bushing 49'forthe lift rod 48', and-the lever 52 and arm 53 of the plunger 45 extend between these'brackets;

In order to hold themember 45. from turning and also to guide the .same, the arm '53 of the driven member 45 is provided with a guide rod '75 slidable' in a vertical passage'lfi formed in the bushing '49, the passage 76 having a vent hole 77 into the crank case to prevent the passage from 45 or screw 47 thereof and valve stem 43 is'ta ken up by spring 56. During the lifting operation of the cam 51, the clearance between the surfaces 54 and 55 is taken up by the pivotal movement of the lever 52 upwardly against the-spring 56,- and I after the clearance is thus taken -up,:the' lever.52 and member 45'are thrust upwardly as a unit against the end of the valve stem 43, thus opening;

the valve. 1 i a I 'When the cam 51 passes out of engagementwith the lift rod 48, and the valvecspring 44 isfree to react, the parts return to'their normalposition, and thespring 56 moves the lever 52downwardly on its pivot relatively to the member 45 thus again forming the clearance between'the surfaces 54 and 55. l,-

: In either embodiment of my invention, the normal clearance varies onlyslightly-under all 'temperature conditions, and is'taken up by a'wedging or rolling inaction. P r

What I claim is:

"In an operating .mechanism for:valves of .in-

ternal combustionengines, the 'combinatiomof two motion transmitting members, one.being"a:

push rod, and compensating means for transferring the movement ofthe push-rod to the other member, the other member having-an arm extending at an angle to the push rod, said com pensating means including a lever pivoted to the outer end of said arm and extendingunder the same towards the push rod and formed with a cam surface eccentric with its pivotal axis, 'said' arm being formed with a surface with which the cam surface coacts and a spring interposed between said arm and the compensating lever.

- 'BROR G.- ANDERSON-71::

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