US2630792A

US2630792A - Automatic tappet

Info

Publication number: US2630792A
Application number: US778831A
Authority: US
Inventors: Herbert H Engemann
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-10-09
Filing date: 1947-10-09
Publication date: 1953-03-10
Anticipated expiration: 1970-03-10

Description

H. H. ENGEMANN AUTOMATIC TAPPET 3 Sheets-Sheet 2 22 225112 222: HL'RBERT H. ENGEMANN.

March 10, 1953 Filed Oct. 9, 1947 March 1953 H. H. ENGEMANN 2,630,792 1 AUTOMATIC TAPPET Filed Oct. 9, 947 5 Sheets-Sheet 3 IEZEHZCJF HERBERT H. ENGEMANN Patented Mar. 10, 1953 UNITED STATES PATENT OFFICE AUTOMATIC TAPPET Herbert H. Engemann, Cleveland Heights, Ohio Application October 9, 1947, Serial N 0. 778,831

27 Claims.

This invention relates to automatically adjustable tappets or similar self-adjusting valve linkage devices for use in connection with internal combustion engines. As to certain features, this application constitutes further improvements over my prior Patents Nos. 2,176,895, 2,404,478, 2,406,812, 2,424,389 and my pending application for Patent Serial No. 538,653, filed June 2, 1944 and now Patent Number 2,419,316, issued April 22, 1947.

The purposes and desirability of an automatically adjustable tappet or similar self-adjusting valve linkage devices have been set forth in detail in my above referred to patents and application and will not be herein repeated. The structures disclosed in my prior patents and application provide very satisfactory self-adjusting valve linkage devices which will operate automatically to maintain a predetermined clearance (which may be zero clearance) in a valve linkage of an internal combustion engine, in-

dependently of the variations in dimensions of the elements of the linkage produced by the temperature changes encountered in the normal operation of the engine under all ambient conditions. Such self-adjusting devices generally comprise a pair of threadably cooperating parts whose relative position determines the effective length of a portion of the valve linkage and hence determines the clearance available in such linkage. The threadably cooperating parts are torsicnally biased by a suitable spring in the direction to produce zero or negative clearance in the valve linkage. An inertia weight is movably mounted with respect to the clearance adjusting parts and in each operating cycle of the valve linkage, such inertia weight is movably displaced with respect to the threadably cooperating parts. Such relative movement of the inertia weight is employed to produce a torsional impact upon the threadably cooperating parts in the direction tending to relatively rotate such parts so as to produce a positive clearance. Hence the valve linkage is continually adjusted to automatically maintain a desired clearance therein.

This invention provides further improvements in self-adjusting valve linkage devices of the type disclosed in my above referred to prior patents and application which not only improve the reliability and accuracy of operation of such self-adjusting valve linkage devices but also provide a substantial increase in the operating life of the critical components of the valve linkage devices, and further, permits such devices to be more economically manufactured than the constructions heretofore known. l

A self-adjusting valve linkage device embodying this invention is not aifected by angular accelerations of the tappet valve linkage in which the device is incorporated. In the constructions of my prior patents and application, the inertia element had a combined rotational and sliding movement with respect to the member on which it operated. Any angular acceleration of such member on which the inertia element operated very often caused unwanted motion of the inertia element so as to throw such element out of time with the motion of the valve linkage, th reby erroneously affecting the clearance adjustment produced by the adjusting device so that the desired clearance of the valve linkage was not maintained. In constructions embodying the present invention, the inertia element throughout the major portion of its movement is guided so that it can only slide on the guiding member in a direction generally parallel to the force transmitting direction of the valve linkage. fore, any forces resulting from angular acceleration of the valve linkage will be at right angles to the motion of the inertia element and resisted by the guiding means provided so as to have a negligible effect upon the torsional impacts imparted by the inertia element to the threadably cooperating parts of the self-adjusting device.

A further feature of my invention lies in the provision of a construction in which the impact of the inertia element upon one of the threadably cooperating parts is cushioned in such a way as to substantially absorb that component of impact which does not contribute to the rotational adjusting action desired upon the threadably cooperating parts. Such construction obviously results in longer life of the parts and quieter operation, without adversely affecting the clearance adjusting action.

An automatic tappet or similar self-adjusting device embodying this invention has the further feature of eifecting adjustments of the rotatably cooperating parts in the direction to provide a positive clearance of the valve linkage twice during each cycle of operation of the valve linkage. In other words, the inertia element effects the desired clearance adjustment in the direction to produces, positive clearance in the linkage by either direction of its inertia induced movements relative to the threadably cooperating parts.

Still another feature of this invention is the provision of an improved arrangement of stops for limiting the range of clearance adjustment which may be automatically eifected. The clearance adjusting stops operate such as to positively limit the amount of adjustment to a safe limit of Thereoperating clearance in case of malfunctioning of the mechanism, as by failure of the torsion spring, and yet accomplish such limiting without producing a thread look condition.

Still another feature of the present invention is the provision of readily accessible means for locking the clearance adjusting device of the valve linkage in its most desirable operating positionprior to assembly in an engine to facilitate the assemblage of the same in an internal combustion engine, Whereafter the locking element may be conveniently removed to place the adjusting device in operating condition.

Accordingly, it is an object of this invention to provide an improved clearance adjusting device for valve linkages, and particularly, an improved automatically adjustable tappet for maintaining a desired operating clearance in the valve; linkage of an. internal combustion engine.

: Another object of this invention is to provide an improved s'elf adjustir'ig valvelinkage device of the inertia hammer type wherein the adjusting movements of the inertia hammer are rendered substantially independent of angular accelerations of the valve linkage in which the adjusting device is incorporated.

$till another object of this invention is to provide' an improved inertia hammer type, self-adgusting valve linkage device wherein the impact blows imparted by the inertia hammer for clearanceadjustment purposes are resiliently cushioned, thereby prolonging the life of theparts and producin substantially quieter operationof the device.

A further objectof this invention is to provide an automatically adjustable tappet for like device wherein an inertia hammer element operates upon threadably cooperating adjusting parts of the device at least twice during each cycle of operation of the tappet to reduce the effective length of the tappet and thereby increase the operating clearance of the valve linkage with which the tappet is associated.

S t-ill another object oi this invention is to pr vide an improved adjustable tappet construction characterized by the provision of positive stops for limiting the range of automatic adjustment of the tappetto a safe range of operating clearance, and to effect such limitation without producing thread-lock of the threadably cooperating parts i of the adjustable tappet,

A particular object of this invention is to provide an improved self-adjusting valve linkage construction characterized by the simplicity and ease of manufacture of its components and the convenience of assembly of the device in the valve linkage of an internal combustion engine.

The specific nature of the invention, as well as other objects and advantages thereof will become apparent to those skilled in the art from the following detailed description of the annexed sheets of drawings which, by Way of preferred example only, illustrate several specific embodiments of the invention.

On the drawings:

Figure l is a schematic sectional view illustrating one well known form of valve linkage in which an adjustable clearance device embodyin this invention may be incorporated;

Figure 2 is a schematic sectional view illustrating the manner of incorporating an adjustable clearance device embodying this invention in a modified form of valve linkage;

Figure 3 is a schematic, sectional view illustrating the incorporation of a clearance adjusting 4 device embodying this invention in the rocker arm of a valve linkage;

Figure 4 is a longitudinal sectional view of a clearance adjusting device embodying this invention, showing the elements thereof in their normal positions;

Figure 5 is a view similar to Figure 4 but showing the elements thereof in their positions following the impact of the inertia hammer with the threadably adjustable parts;

Figure 6 is an exploded sectional View of the elements of the assembly of Figure 4;

'igure *7 is a. partial elevational view of the adjusting screw, illustrating a modified form of construction of the aperture receiving the guide Figures 8 and 9 are respectively elevational and longitudinal sectional views of a modification of this invention utilizing a resilient pin as the impact cushioning element;

Figures 10' and 11 are respectively elevational and longitudinal sectional views of a further modification oithis invention wherein a single pin is utilized both for cushioning and impact transmission purposes; and

Figure 12- and Figure 13 are respectively elevational and longitudinal sectional views of a still further modification of this invention wherein a pair of impact pins are employed to respectively receive torsional impact from the inertia hammer in either of its two directions of movement.

As shown on the drawings:

In Figure 1 there is shown a well known form of valve operating linkage for an internal combustion engine in which linkage a clearance adjusting device embodying this invention may be conveniently incorporated. Such linkage is commonly employed in a valve-in-heacl type of internal combustion engine and comprises a cam shaft l having a radially enlarged cam portion in which operates against a conventional, vertically movable tappet 2. Intermediate the top end of tappet 2 and the rocker arm 3, a clearance adjusting device it embodying this invention may be mounted as a substitute for the conventional push rod. At its opposite ends the adjusting dc vice isprovided with'ball shaped ends lea and HR) which respectively cooperate with correspondingly shaped sockets 2a and 321, provided. in the tappet 2 and rocker arm Rocker arm 3 is directly connected in conventional fashion to a stem of a valve d which lssprlng biased to a closed position by valve spring 5.-

Alternatively, a clearance adjusting device embodyi'ng this invention may be mounted as shown in Figure 2 to operate directly against the valve stem 5a of a valve 5. In such modification the valve stem 5c is provided with: a ball shaped end 62) for seating in a ball-shaped recess Ha pro vided in'a coupling member H while the bottom surface of the adjusting device is fiat to cooperate directly with the caniming surfaces of cam shaft I. 7 As a still further alternative, as illustratedin Figure 3, a clearance adjusting device embodying this invention may be mounted directly on the valve operating arm of a rocker arm '1, in which case the screw member l3 of the clearance adjusting device H1 is provided with a ball shaped end lilo to cooperate directly with the stem portion to of a valve-in-head type valve. Operating movement for the rocker arm 1" is supplied in conventional fashion from cam shaft 1 by a tappet 2 and pushrod 9. v

In all of the aforedescribd applications or a clearance adjusting device embodying thi invention, it is apparent that variation of the effective length of the clearance adjusting device Ill will vary the operating clearance available in the valve linkage. In accordance with this invention, such variation in efiective length of the adjusting device It is automatically accomplished by inertia movements produced by the normal operation of the valve linkage and hence, any desired clearance may be maintained in the valve linkage. In the specific examples to be hereinafter described in detail, it will be assumed that it is desired to maintain a zero clearance in the valve linkage.

In order that no confusion shall arise as to the use of certain terms hereinafter employed, it is believed desirable to set forth the following definitions:

By negative clearance is meant a condition of valve adjustment in which the valve is prevented from closing or seating when the tappet is riding on the base circle or small diameter of the cam.

By positive clearance is meant the condition of valve adjustment in which there is excess or undesirable valve clearance preventing the valve from obtaining its full lift.

By zero clearance is meant a condition of valve adjustment in which all undesirable clearance has been removed and the valve linkage is operating with the theoretically correct clearance.

By adjusting positively is meant the process of taking up undesirable st motion in the valve linkage, or the process of increasing the effective length of the valve linkage until the desired valve operating clearance is obtained.

By adjusting negatively is meant the process of reducing the effective length of the valve linkage until the desired valve operating clearance is obtained.

The clearance adjusting device Ill embodying this invention will be particularly described and illustrated in connection with the valve linkage of the type illustrated in Figure 2; however, it should be distinctly understood that the clearance adjusting device embodying this invention may be equally well applied to any other form of valve linkage such as those illustrated in Figures 1 and 3.

Referring now particularly to Figures 4 through 6, it will be seen that a clearance adjusting device embodying this invention comprises a hollow cylindrical body portion I2 having a fiat bottom surface I2t resting upon the cam surface id of the cam shaft I and a generally cylindrical interior bore I2b having a bottom end wall I20, an open top end IZd (Figure 6) and an interiorly projecting shoulder I2e disposed immediately adjacent the top open end. The side walls of body portion I2 are preferably provided with a plurality of apertures 52 which permit the entry of splashed lubricant fluid into the interior of the body portion I2 for the purpose of lubricating the parts disposed therein.

A nut member It is positioned within body portion I2 near the top open end thereof by an integral flange portion I la thereon which seats on the internally projecting shoulder IZe. Nut member I I is internally threaded and such threads cooperate with a threaded portion I So formed on an adjusting screw member I3. Immediately adjacent threaded portion lad, adjusting screw I3 is provided with an enlarged portion I3b having helical grooves I3c formed thereon for a purpose to be described. Adjacent the enlarged portion IN) is a cylindrical shank'portioh I3d which projects well into the interior of the bore I2?) of body portion I2 and terminates immediately adjacent the end wall I20 of the bore I21). At the other end of the threaded portion I3a, the adjusting member I3 is provided with a shaft-like portion I3e which projects out of the body portion I21).

It is therefore apparent that the effective overall length of the clearance adjusting unit II] is determined by the relative threaded position of adjusting member I3 with respect to the nut I4. Furthermore, the possible range of adjustment of the two threadably cooperating parts is positively limited in both directions. In the negative clearance direction, i. e., the direction to increase the overall length of the clearance adjusting device ID, a positive stop is provided by the engagement of the top surface of enlarged portion I3b with the bottom surface of the nut 14. Generally this maximum length of the ad justing device It is selected so as to be sufficiently large tobe capable of providing negative clearance in the valve linkage even under the most extreme operating conditions. In the positive clearance direction, 1. e., the direction of shortening the overall length adjusting device H), the minimum efiective length of the adjusting device H! is determined by the engagement of the end or shank portion I3d of the adjusting screw I3 with the bottom wall I20 of the bore [21). Upon the occurrence of such engagement, any further threaded adjustment of adjusting member I3 into nut I2 would not produce further shortening of the overall length of the adjusting device IE] but would merely raise the nut I2 on the seat provided by the internally projecting shoulder I2e. Therefore, even under the extreme adjustment condition produced by breaking of the torsion spring, the shortening of the adjusting device I I) is positively limited and furthermore, such limiting is accomplished without any possibility of producing a'thread-lock between the adjusting screw I3 and the nut I2.

The pitch of the cooperating threads provided on the nut I4 and the adjusting screw I3 is selected to permit ready relative rotation of these parts but yet are not sufliciently steep so as to permit thread crashing between these two threaded parts upon the application of axial forces to the device It. The adjusting screw I3 is normally urged toward its maximum projecting position by a torsion spring I5. One end of torsion spring I 5 is threaded into the helical grooves I3c provided upon enlarged portion I31) and anchored thereto by the insertion of an axially extending end portion I511, of the spring selectively into one of a plurality of circumferentially spaced axial grooves I31 provided in enlarged portion I3b. Immediately beneath the flange I la, the nut member I4 is provided with a helical groove Idb to receive the other end coils of the spring I 5. A plurality of spring anchoring holes I 4d are provided in circumferentially' spaced arrangement around the flange Ida of nut I 4 to selectively receive the other axially extending end I5b of spring I5. The provision of a plurality of circumferentially spaced anchoring means for the ends of the spring I5 obviously permits the effective torsional stress of such spring to be selected with an unusual degree of accuracy.

To operatively connect the projecting end I3e of adjusting screw I 3 into the valve linkage, there is preferably provided a cap II having a cylindrical recess IIb'in one end thereof -suitably proportioned tosnugly receive the end of projection Be and a ball recess I la in the other end thereof to swivelly mount the correspondingly shaped end of the valve stem. With such an arrangement, it is obvious that rotational movements of the adjusting device about its own axis may freely occur without any effect upon the clearance of the valve linkage.

The spring 15 obviously effects the adjustment of the relative position of adjusting screw 13 and nut M in the negative clearance direction, i. e., at any time that positive clearance exists in the valve linkage, the spring l will operate to increase the efiective length of the clearance adjusting device 10, and thus restore a zero clearance condition, it being'understood that the torsional force exerted by spring 15 is not sufficient to overcome the biasing force exerted by the valve spring.

To effect the adjustment of the effective length of the adjusting device it in the positive clearance direction, this invention contemplates the utilization of an inertia weight slidably mounted for axial movement relative to the adjusting device Ill. The inertia induced, axial movements of such inertia weight produced by the linear accelerations of the adjusting device Ill in the normal movements of the valve linkage are employed to exert relative torsional forces upon the adjusting' screw I3 and nut is in the direction to shorten the overall length of the adjusting device 10.

Thus, the inertia weight may comprise a sleeve l6 which is slidably mounted upon the shank portion 13d of the adjusting screw 13. In the modification of this invention illustrated in Figures e through 6, a helical surface 15a is defined on the sleeve is in any convenient manner, such as by cutting a pair of diametrically opposed recesses 16b in lower end face of the sleeve 16. An abutment H is provided in rigid relationship to the adjusting screw l3 and may conveniently comprise a pin snugly inserted in a' transverse hole I39.

To insure proper impact of abutment pin H with the helical surface Isa, and for other reasons to be later discussed, this invention contemplates the provision of means for resiliently confining the movement of inertia sleeve l5 to substantially an axial path. Such guiding action ture 13g. The relationship between guide pin l3 and its supporting aperture 371 is preferably such as to permit a generally helical movement of guide pin 8 with respect to adjusting screw 53. Such an arrangement may be provided by forming the aperture 1371. in the form of a helically extending slot. as shown in Figures a through 7, or, if desired, a similar arrangement may be achieved by forming the aperture i372 as a cylindrical hole which is substantially larger than the pin it, in the manner illustrated in Figure 7. In either event, a spring is provided to urge the guide pin axially toward the abutment pin H. Such spring may comprise a coil spring i9 which surrounds the shaft portion 13d and abuts against the bottom face of enlarged shaft portion l3b.

Inertia sleeve lfii's counterbored as at liif to provide clearance for spring l9.

Finally, the inertia sleeve 15 is provided with suitable axially extending guide surfaces which cooperate with guide pin: 18' to insure that the sleeve [6 will be resiliently confined to movements in a substantially axial path, Such guide surfaces may be conveniently provided by a pair of diametrically opposed, axially extending slots we cut into the walls of inertia sleeve 16. The guiding action of the pin 18 upon the sleeve i5 is selected so as to insure that the abutment pin I? is initially contacted by an intermediate portion of the helical surface [60, of the inertia member. This relationship is clearly shown in Figure 4.

From the foregoing description, it is apparent that the inertia sleeve 16 is free to shift axially with respect to the adjusting screw [3 under the influence of inertia forces produced by the acceleration and de acceleration of the adjusting device 10 which occur in the normal cycle of operation of the valve linkage. In each cycle of operation of the valve linkage, the inertia sleeve [6 will be axially displaced upwardly with respect to adjusting screw 53 and then displaced downwardly to return to its normal position, as shown in Figure 4. Throughout the major portion of both of these axial movements, the inertia sleeve 56 is resiliently confined to movement along an axial path by the guide pin it. Therefore, any angular accelerations of the adjusting device 13 which may occur will have no substantial effect upon the movement of the inertia sleeve 16 with respect to the adjusting screw 13.

When the inertia sleeve l6 is displaced upwardly with respect to adjusting screw 13, only axial movement of the sleeve will occur until the end wall Hid of axial slot 460 contacts the guide pin l8. Under the impact forces of such contact, the guide pin 43 will tend to be displaced helically in its supporting aperture iflh. Therefore, a torsional or rotative force is exerted upon the adjusting screw member i3 and such force is in the direction to tend to shorten the effective length of the adjusting device it. Furthermore, the axial component of the impact forces thereby produced are resiliently cushioned by the spring i9, thereby substantially eliminating wear upon the contacting parts and producing much quieter operation.

When the inertia sleeve it shifts downwardly with respect to the adjusting screw 13, it again follows a substantially axial path throughout the major portion of its movement until the abutment pin 17 strikes the intermediate portion of the helical surfaces 16a provided on the inertia sleeve Hi. This contact also exerts a torsional or rotative force upon adjusting screw member 13 in the direction of obtaining positive clearance in the valve linkage. Furthermore, such impact produces a torsional reaction force upon the inertia sleeve it which tends to angularly twist the guide pin i8. Since any angular movement of the guide pin [8- is confined by its supporting aperture i371. to movement along a helical path, it is apparent that a compression of the spring l9 will result and hence the impact of inertia sleeve it upon abutment pin I! is also resiliently cushioned. The position of the various operating elements after the occurrence of such impact is illustrated in Figure 5. The spring [9 is, of course, efiective to return the parts to the normal position of Figure 4. without exerting any influence upon the relative rotational position of adjusting screw I3 and the nut M.

From the foregoing description it is apparent that devices constructed according to this invention will automatically operate to maintain a predetermined clearance in a valve linkage. Furthermore, the clearance adjustments will be more positively and rapidly accomplished than in constructions heretofore known by virtue of the fact that the inertia member effects an adjustment in the positive clearance direction twice for each cycle or" operation of the valve linkage. Furthermore, all of the impacts of the inertia member upon the adjusting member are resiliently cushioned to insure long life of the parts and maintain the noise level at a minimum.

To facilitate the assemblage of the clearance adjusting device It! into the valve operating linkage of an internal combustion engine, this invention contemplates the provision of a quickly detachably locking device operating upon the projecting end [3e of the threaded adjusting member l3 which will maintain the theaded adjusting member l3 locked in approximately a normal position with respect to the nut I4 during the assembly operation. Thus, a transverse hole lSk may be provided through projecting portion We and located with respect to the nut It so that when a wire or similar article (not shown) is inserted in the hole Hit and the adjusting member 13 manually screwed into the nut I4 sufiiciently for the wire to engage the nut in frictional locking contact, then the overall length of the adjusting device will be approximately equal to the normal length of such device when assembled in the valve linkage. This length condition is illustrated in Figure 5. The device may then be readily assembled in the valve linkage and the wire Withdrawn from the aperture l37c to unlock the two threaded parts and restore the adjusting device to its opera-ting condition.

It should be particularly noted that an automatic clearance device constructed in accordance with this invention has all of the operating parts thereof. disposed within the interior of body portion l2 and hence protected from damage due to rough handling during assemblage. While the side wall apertures I27 insure adequate supply of lubrication to the movable parts of the adjusting device, such apertures in no manner detract from the completely enclosed characteristics of the mechanism and it is thereby assured that upon breakage of any parts, there is no possibility of such broken parts finding their way to other parts of the engine where they may cause damage.

Those skilled in the art will recognize that the particular arrangement of the inertia sleeve iii, the abutment pin I! and guide pin l8 heretofore described represent only one of a variety of possible constructions which will yield similar desirable results. Thus, in Figures 8 through 13, there are illustrated three additional arrangements of the inertia sleeve, abutment pins and guiding pins.

In the modification of Figures 8 and 9, the construction of the inertia sleeve l6 and the abutment pin H is substantially identical to that heretofore described. However, in this modification the guiding pin 2| is formed of resilient material and is snugly mounted in a suitable transverse aperture 22 provided in the shank portion I35. To facilitate the flexing of the ends of the resilient pin 20 under the impact of the inertia sleeve Iii, the end wall ltd of the axially extending slot I50 of the inertia sleeve is cut away on the inner side thereof, as indicated at It Furthermore, the width of slot-16c is selected substantially larger than flexible pin 20 to permit helical iiexing of the ends or" the pin.

It will be recognized that the modification of Figures 8 and 9 will provide resilient cushioning of the impact of the inertia sleeve in the downward direction against the abutment pin l1; also, resilient cushioning of the upward movement of the inertia sleeve with respect to the adjusting screw l3. However, no additional torsional impact wil be imparted to the adjusting screw I3 by the upward movement of the inertia sleeve unless, of course, the bottom portion of the slot lfic is provided with a helical configuration.

In the modification illustrated in Figures 10 and 11, a single pin 22 is employed as both the abutment and guiding pin for the inertia sleeve 23. The pin 22 is loosely mounted in a helically extending, transverse slot 24 provided in the lower extremity of the shank portion l3d of the adjusting screw l3. A spring 25 is provided for urging the pin 22 in an axial direction and such spring may be conveniently mounted within an axial hollow bore I3m formed in the end of shank portion l3d. Spring 25 bottoms upon a transverse pin 28.

The inertia sleeve 23 is provided with a pair of diametrically opposed, downwardly opening, axially extending slots 23a which cooperate with the pin 22 so as to resiliently oppose any tendency of the inertia sleeve 23 to rotate relative to the adjusting screw [3.

When the inertia sleeve 23 moves downwardly relative to the adjusting screw l3 a torsionalimpact is thereby imparted to the adjusting screw through the cooperation of the pin 22 and the helical walls of the transverse aperture 22. Such impact is,'of course, cushioned by the spring 25.

In the reverse direction of inertia movement of the inertia sleeve 23 with respect to the adjusting screw I3, no torsional impact is imparted to the adjusting screw. Such reverse movement may, if desired, be cushioned by the provision of a, spring 27 which surrounds the upper portion end of the shank portion Hid of the adjusting screw l3 and is secured thereto by having a reduced diameter end coil 21a thereof engaged in an annular groove I311. The upper end of the inertia sleeve 23 is counterbored as indicated at 231) to provide clearance for the spring 21 throughout most of the range of upward movement of the inertia sleeve 23, whereafter the shoulder 23d formed at the base of the counterbore 23?) engages the spring 21 and resiliently arrest-s the further upward movement of inertia sleeve 23.

In the modification of Figures 12 and 13, the bottom end of the shank portion 13d of the adjusting screw i3 is again provided with an-axially extendingbore I30. A guide pin 30 is loosely inserted in a transverse aperture 3i .formed in the walls surrounding the bore I30. The aperture 3! may either comprise a cylindrical opening of substantially larger diameter than the guide pin 3E, similar to the construction of the modification of Figure 7, or, if desired, may comprise a generally helically extending slot similar to that shown in the modification of Figures 4 through 6. In either event, the guide pin 30 is axially biased toward the extreme position permitted by the aperture 3| by a spring 32 which is bottomed upon a transverse pin 33.

The inertia sleeve 34 employed in this modification is provided with a set of diametrically opposed, helically walled recesses 34a and 34b in each end face of the inertia sleeve. The helical surface Sta of the top recess cooperates with a projecting portion'of an 'upper'fixed abutment pin 36 which xs' transversely" mounted in the shank portion 13d of the adjusting screw l3 while the helical surfaceiibof the bottom recess cooperates with the projecting portions of the pin 33. The helical surfaces 34a and 3417 are so shaped as to impart rotative impactsto the adjusting screw [3 in the same direction by either of the respective inertia induced upward and downward movements of the inertia sleeve with respect to the adjusting screw. The inertia sleeve is resiliently guided along an axial path by a pair of diametrically opposed, axially extending slots 340 provided in the central portion of the inertia sleeve which respectively cooperate with the projecting end of the" guide pin 30.

It is therefore apparent that in the modification of Figures 12 and 13', a pair of rotative impacts are imparted to the adjusting screw 13 in the direction'to increase the positive clearance in the valve linkage during each cycle of operation of such linkage; Furthermore, upon the occurrence of such impact in either direction of movement of the inertia sleeve 34, the inertia sleeve 34 tends to shift in a; rotational direction and this tendency is resiliently opposed by the guide pin 30 and its biasing spring; Hence, the impacts of the inertia sleeve upon the cooperating abutment pin are resiliently cushioned.

The incorporation of the clearance adjusting device embodying this invention in the valve linkage of Figure 1 is obvious from thepreceding description. To incorporate such in a linkage similar to that of Figure 3, the body portion [2 and the nut Id may be eliminated. Instead the valve arm Id of rocker arm T is interiorly threaded to receive adjusting" screw I3" and exteriorly grooved to mount torsion spring 15. The inertia sleeve I6, guide pin 18 and abutment pin 11' are identical in construction and operation to the same elements of Figures 4 through 6.

Therefore, it is apparent that this invention provides a plurality of simple, economically manufacturable constructions of clearance adiustin'g devices for valve linkages. Such devices will not only reliably and accurately function to maintain a desired clearance condition in a particular valve linkage, but, in addition, will provide longer life of the operating parts and much valve linkages comprising a pair of threadably cooperating members whose relative positions determine the efiective length of the mechanism, resilient means operable between said members I to relatively urge said members in the direction of increasing their effective length, an inertia hammer slidably mounted on one of said mem bers for axial and rotational movements relative thereto, a spring loaded member engageable with said hammer for resiliently opposing rota tional movements ofsaid hammer with respect to its supporting member, a helically extending surface on said hammer, and an abutment on one of said members engageable by said helically extending surface as said hammer moves axially 7 whereby a torsional force is imparted to sa d 12 membersin the di'rectionto shorten their eiiective length and the-impact of said inertia hammer with said abutment means is cushioned by said second resilient means.

2. An automatic clearancemechanism ior valve linkages comprising a pair of threadably cooperating members whose relative positions determine the eiiective length of the mechanism, resilient means operable between said members to relatively urge said members in the direction of increasing their eiiective length, an inertia weight mounted for oscillatin axial movements relative to said members, means for converting by impact the axial movement of said weight in at least one direction into a' rotational force on one of said members in the direction to shorten the efiective length oi'said members, and a spring coaxially disposed with respect to said members for cushioning the'impact' blows produced by said Weight.

3. An automatic clearance mechanism for valve linkages comprising a pair of threadably cooperating members whose relative positions determine the effective length of the mechanism, resilient means operable between said members to relatively urge said members in the direction of increasing their efiective length, an inertia weight slidably mounted on oneof said members for rotational and axial movements, a guide on said one member for controlling the inertiainduced movements of said weight to substantially prevent rotative movement of said weight relative to said one member throughout the major portion of the axial movement of said weight, and means for converting the end portion of the axial movement of said weight in one direction into a torsional impact on one of said members in the direction-to shorten the effective length oi the members, whereby the clearance adjustments produced by said weight are made substantially independent of angular accelerations of said members.

4. An automatic clearance mechanism for valve linkages comprising a pair of threadably cooperating members whose relative positions determine the effective length of the mechanism, resilient means operable between said members to relatively urge said members in the direction of increasin their effective length, an inertia weight slidably mounted on one of said members for rotational and axial movements, a guide for controlling theinertia-inducedmovements of said weight to substantially prevent rotative move ment of said weight relative to said one member throughout the major portion of the axial movement of said weight, and means for converting the end portion of the axial movement of said weight in one direction into a torsional impact on one oi said members in the direction to shorten the effective length of the members, whereby the clearance adjustments produced by said weight are made substantially independent of angular accelerations of said members, said guiding means being constructed and arranged to resiliently oppose rotative movements of said weight, thereby cushioning the impact blows exerted by said weight upon said one member.

5. An automatic clearance mechanism for valve linkages comprising a pair of threadably cooperating members whose relative positions determine the effective length of the mechanism, resilient means operable between said members to relatively urge said members in the direction of increasing their effective length, an inertia weight slidably mounted on one of said members for roforce on said one member in a direction to shorten the effective length of said members.

6. In a vibratory mechanical linkage of the type in which there are intermittently actuated driving and driven links with an effective operating clearance in the linkage, which clearance is closed each cycle by the movement of the driving link relative to the driven link and is restored upon the return of the driven linkto initial position, and adjustment means are provided to regulate such clearance, the improvement which comprises: an inertia member mounted for free movement on one of said moving links substantially in the direction of operating movement of said one link, means for automatically moving said adjustment means by impact from inertia produced movement of said inertia member in one direction relative to said one link, means for cushioning the movement of said inertia member during said impact, said cushioning means including means operated by reverse inertia movement of said inertia member to additionally move said adjustment means to increase said clearance, and restoring means automatically operative to restore the adjustment means to the position of desired clearance.

'7. A clearance adjustment mechanism for a valve linkage comprising a pair of threadably cooperating parts whose relative positions determine the effective length of the mechanism, means for connecting said parts in a vibratory valve linkage so that the vibratory movements of said parts are substantially axial with respect to said parts, an inertia weight axially movable relative to said parts, means for deriving from the inertia-induced axial movement of said inertia weight in one direction a rotative force on one of said parts in a direction to decrease the effective length of the mechanism, and means for deriving from the inertia-induced reverse axial movement of said inertia weight a rotative force on one of said parts also in a direction to decrease the eifective length of the mechanism.

8. A clearance adjustment mechanism for a valve linkage comprising a pair of threadably cooperating parts whose relative positions determine the effective length of the mechanism, means for connecting said parts in'a vibratory valve linkage so that the vibratory movements of said parts are substantially axial with respect to said parts, an inertia weight axially movable relative to said parts, means for deriving from the inertia induced axial movement of said inertia weight in one direction a rotative force on one of said parts in the direction to decrease the eifective length of the mechanism, means for deriving from the inertia induced reverse axial movement of said inertia weight a rotative force on one of said parts also in a direction to decrease the effective length of the mechanism, said last mentioned means including means for resiliently opposing rotative movements of said inertia weight relative to one of said parts, thereby cushioning the impact forces exerted by said inertia Weight on said part.

9. A clearance adjustment mechanism for a valve linkage comprising a pair of threadably cooperating parts whose relative positions determine the effective length of the mechanism, means connectingsaid part in a vibratory valve linkage where the vibratory movements of said parts are substantially axial with respect to said parts, a pair of axially spaced abutments on one of said parts, an inertia weight axially movable relative to said one part intermediate said abutments, a first helical surface on said inertia weight cooperating with one of said abutments to impart a rotative force on said one part in a direction to decrease the effective length of the mechanism derived from inertia induced axial movement of said inertia weight in a direction toward said one abutment, a second helical surface on said inertia weight engageable with said other abutment to produce a rotative force on said one part also in a direction to decrease the effective length of the mechanism from the inertia-induced reverse axial movement of said inertia weight, and means for resiliently guiding said inertia weight in an axial path, thereby cushioning the impact forces exerted on said weight by respective contacts with said abutments.

10. An automatic tappet comprising a hollow body portion open at one end, an adjusting member coaxially disposed within said body portion and thread ably engaged therewith, said adjusting member having a rod-like end projecting outwardly through said open end to determine the efiective length of the tappet, resilient means within said body portion urging said adjusting member toward the position of maximum projectlon, an inertia weight axially oscillata'bly mounted within said body portion, means within said body portion for converting at least a portion of the oscillating movements of said weight into torsional forces on said adjusting member in the direction to shorten the degree of projection of said end of the adjusting member, said bore of said body portion having a stop sur face axially remote from said open end, and the inserted end of said adjusting member being engageable with said stop surface to limit the adjustment of said adjusting member in the shortening direction.

11. An automatic tappet comprising a hollow body portion open at one end, a nut normally seated in the bore of said body portion but being axially movable in the direction of said open end, an adjusting member disposed within said body portion and having a threaded portion engag ing said nut. said adjusting memberhaving a rod-like end projecting outwardly through said open end to determine the effective length of the tappet, said bore of said body portion having a stop surface axially remote from said open end, and the inserted end of said adjusting member being engageable with said stop surface to limit the adjustment of said adjusting member in the shortening direction without thread look by shifting said nut from its seat.

12. An automatic tappet comprising a cupshaped body member having a generally cylindrical bore open at one end, said bore having an internally projecting shoulder near said open end, an externally flanged nutseated on said shoulder, an adjusting member insertable in said bore and having a threaded portion cooperating with said nut and an' enlarged portion disposed inwardly of said nut to limit outward. screwing of said adjusting memhensaid adjustingmemher having one end portion projecting out of said open end to determine the eilective length of the tappet and the other end portion projecting inwardly adjacent the end wall of said here, resilient means within said body portion urging said adjusting member toward the position or" maximum outward projection, an inertia weight axially oscillatably mounted within said loody portion, means within said body portion to convert at least a portion of the oscillating movements of said weight into torsional forces on said adjusting member in the direction to shorten the degree of projection of said end of the adjusting member, said other end portion of the adjusting member being engageable with said end wall to limit further shortening of the tappet without thread look by shifting said nut axially from its seating position.

13. The combination defined in claim it) wherein said resilient means comprises a helical torsion spring, said nut and said enlarged portion respectively having external helical grooves thereon for respectively receiving the end coil of said spring, and said flange of the nut having a plurality of circumferentially spaced holes therein for selectively anchoring the adjacent end of said spring.

1a. A clearance adjustment mechanism for a valve linkage comprising a pair of threadahly cooperating parts whose relative positions determine the efiective length of the mechanism, an inertia weight slidably mounted on one of said parts for axial movements relative thereto,

a first abutment fixed on said one part, a helical surface on said weight cooperaole with abutment to exert a rotative force on said one part in the direction to shorten the mechanism by inertia-induced axial movements of said weight; a second abutment mounted on said one part for limited, resiliently opposed movement in a generally helical path, and a pair of axially disposed surfaces on said inertia weight slidabiy cooperating with said second abutment to resiliently oppose rotative movements or" said weight with respect to said one part, thereby cushioning the impacts of said helical surface on said first abutment.

15. A clearance adjustment mechanism for a valve linkage comprising a pair of threadaoly cooperating parts whose relative positions determine the efiective length of the mechanism, an inertia weight slidably mounted on one of said parts for axial movements relative thereto, a first abutment fixed on said one part in projecting relation. thereto, a helical surface on said weight cooperable with said first abutment to exert a rotative force on said one part in the direction to shorten the mechanism by inertia-induced axial movement of said weight, a second abutment mounted on said one part in projecting relation thereto for limited movement in a generally helical path, a spring urging said second abutment axially, and a pair of spaced, axially disposed surfaces on said inertia weight slidably cooperating with said second abutment to resiliently oppose rotati-ve movement of said weight with respect to said one part; thereby cushioning the impacts of said helical surface on said first abutment.

16. A clearance adjustment mechanism for a. valve linkage comprising a pair of threadably cooperating parts whose relative positions determine the effective length of the mechanism, an inertia weight slidably mounted on one or" (iii 16 said parts for axial movements relative thereto, afirst abutment fixed on said one part, a heli cal surface on said weight cooperable with said abutment to exert a rotative force on said one part in the direction to shorten the mechanism by inertia-induced axial movements of said weight; a second abutment mounted on said one part for limited movement in a generally helical path, a spring urging said second abutment axially, said inertia weight having an axially extending slot slid-ably receiving second abutment therein, thereby resiliently opposing rotative movements of said weight relative to said one part, the end wall of said slot being engageaole with said second abutment by reverse, i-ertia-induced, axial movement of said weight, thereby exerting additional rotative force on said one part in a direction to shorten the mechanism.

17. A clearance adjustment mechanism for a valve linkage comprising a pair of threadably cooperating parts whose relative positions determine the eiiective length of the mechanism, one of said parts having an axially extending, cylindrical shank, an inertia weight comprising a sleeve slidably mounted on said shank, a first pin fixedly mounted in said shank in transverse, projecting relation thereto, a helical surface on said sleeve engageable with said first pin to impart a rotative force to said one part in the direction to shorten the mechanism by inertiainrluced axial movement of said sleeve in one direction, said shank having a transverse aperture therethrough axially spaced from said first pin, a second pin loosely inserted in said aperture so as to be movable in a limited, generally helical path with respect to said one part, a spring urging said second pin axially, said sleeve having an axially extending slot receiving the projecting end of said second pin, thereby resiliently opposing rotative movement of said sleeve with respect to said one part, the end wall of said slot being engageable with said second pin by reverse, inertia-induced, axial movement of said sleeve to impart additional rotative force to said one part in the direction to shorten the mechanism.

18. A clearance adjustment mechanism for a valve linkage comprising a pair of threadably cooperating parts whose relative positions determine the effective length of the mechanism, one of said parts having an axially extending, cylindrical shank, said shank having a pair of axially spaced, transverse apertures therein, a first pin fixedly mounted in one of said apertures and projecting therefrom, a second pin loosely mounted in said second aperture so as to have limited helical movement therein, a spring mounted on said shank and urging said second pin axially towards said first pin, and an inertia sleeve sli ably mounted on said shank intermediate said first and second pins, said sleeve having a helical walled recess in the end face thereof adjacent said first pin and cooperable with said first pin to impart a rotative force to said one part by inertia-induced movement of said sleeve, said sleeve also having an axially extending slot receiving said second pin, thereby resiliently opposing rotational movement of said sleeve with respect to said one part.

19. A clearance adjustment mechanism for a valve linkage comprising a pair of threadably cooperating parts whose relative positions determine the effective length of the mechanism, an inertia weight slidably mounted on one of said parts for axial movements relative thereto, an abutment fixed on said one part, a helical surface on said weight cooperable with said abutment to exert a rotative force on said one part in the direction to shorten the mechanism by inertia-induced, axial movement of said weight, a projecting leaf spring element secured to said one part in axially spaced relationship with respect to said abutment, and means on said weight slidably engaged with said spring element to resiliently oppose rotational movement of said weight with respect to said one part, thereby cushioning the impact forces exerted by said weight on said abutment.

20. A clearance adjustment mechanism for a valve linkage comprising a pair of threadably operating parts whose relative positions determine the effective length of the mechanism, an inertia weight slidably mounted on one of said parts for axial movements relative thereto, an abutment fixed on said one part, a helical surface on said weight cooperable with said abutment to exert a rotative force on said one part in a direction to shorten the mechanism by inertia-induced, axial movements of said weight, a projecting resilient pin secured to said one part in axially spaced relationship with respect to said abutment, an axially extending slot in said inertia weight slidably receiving said flexible pin, thereby resiliently opposing rotational movement of said weight with respect to said one part, said slot having an end wall engageable with said pin to resiliently limit inertia induced, axial movement of said weight in the reverse direction.

21. A clearance adjustment mechanism for a valve linkage comprising a pair of threadably cooperating parts whose relative positions determine the effective length of the mechanism, one of said parts having an axially extending, cylindrical shank, an inertia weight comprising a sleeveslidably mounted on said shank, a first pin fixedly mounted in said shank in transverse, projecting relation thereto, a helical surface on the end face of said sleeve engageable with said first pin to impart a rotative force to said one part in the direction to shorten the mechanism by inertia-induced, axial movement of said sleeve in one direction, a resilient pin mounted in said shank in transverse projecting relation thereto and axially spaced from said first pin, said inertia sleeve having an axially extending slot slidably receiving said resilient pin, thereby resiliently opposing rotational movement of said weight with respect to said one part, and said slot having an end wall engageable with said pin to resiliently limit axial movement of said weight in a reverse direction.

22. A clearance adjustment mechanism for a valve linkage comprising a pair of threadably cooperating parts whose relative positions determine the effective length of the mechanism, one of said parts having an axially extending, cylindrical shank, an inertia weight comprising a sleeve slidably mounted on said shank, said shank having a transverse aperture therethrough, a pin loosely mounted in said aperture and projecting therefrom, said pin being helically movable in said aperture, resilient means urging said pin axially, and an abutment surface on said inertia sleeve engageable with said pin by inertia-induced, axial movement of said sleeve on said one part, thereby imparting a cushioned torsional impact to said one part in a direction to shorten said mechanism.

23. The combination defined in claim 22 wherein said shank portion has a hollow bore traversed by said pin and said resilient means comprises a spring mounted in said bore.

24. A clearance adjustment mechanism for a valve linkage comprising a pair of threadably cooperating parts whose relative positions determine the effective length of the mechanism, one of said parts having an axially extending, cylindrical shank, an inertia weight comprising a sleeve slidably mounted on said shank, said shank having a transverse, helically extending slot therein, a pin loosely mounted in said slot and projecting therefrom, resilient means urging said pin axially, said sleeve having an axially extending slot slidably receiving said projecting pin end, thereby resiliently opposing rotative movements of said sleeve on said one part, and an end wall for said slot engageable with said pin by inertiainduced, axial movement of said sleeve on said one part, thereby imparting a cushioned torsional impact to said one part in a direction to shorten said mechanism.

25. An automatic tappet comprising a hollow body portion, an adjusting member coaxially disposed within said body portion and threadably engaged therewith, said adjusting member having only a shaft-like end portion projecting out of one end of said body portion, resilient means within said body portion urging said adjusting member toward the position of maximum projection, an inertia weight axially oscillatably mounted within said body portion, means within said body portion for converting at least a portion of the oscillating movements of said weight into torsional forces on said adjusting member in the direction to shorten the degree of projection of said end of the adjusting member, and means on said projecting end of the adjusting member movable into frictional engagement with a surface of said body portion for detachably locking said adjusting member in a fixed threaded position with respect to said body portion, whereby said tappet may be locked in a normal position of adjustment for assemblage in a valve linkage and thereafter released.

26. An automatic tappet comprising a cupshaped body member having a generally cylindrical bore open at one end, said bore having an internally projecting shoulder near said open end, an externally flanged nut seated on said shoulder, an adjusting member insertable in said bore and having a threaded portion cooperating with said nut and an enlarged portion disposed inwardly of said nut to limit outward screwing of said adjusting member, said adjusting member having one end portion projecting out of said open end to determine the effective length of the tappet and the other end portion projecting inwardly adjacent the end wall of said bore, resilient means within said body portion urging said adjusting member toward the position of maximum outward projection, an inertia weight axially oscillatably mounted within said body portion, means within said body'portion to convert at least a portion of the oscillating movements of said weight into torsional forces on said adjusting member in the direction to shorten the degree of projection of said end of the adjusting member, said other end portion of the adjusting member being engageable with said end wall to limit further shortening of the tappet without thread look by shifting said nut axially from its seating position, said outwardly projecting end of the adjusting member having an aperture therethrough for selectively receiving a lock member, said aperture being located relative to said nut so that said lock member will frictionally engage said nut to detachably lock said nut and adjusting member together, when said adjusting I91 member ismoved: to. a median adjustment;v positinn for assemblage purposes.

- 27 A clearance: adjustment. mechanism, for a valve; linkage comprising a pair of threadablycooperating parts whose-relative positions deter.- mine the effective length of the. mechanism, one. of said parts. having an axially extending cy1indrical shank, an: inertia, weight comprising. a.

sl'eevesiidabiy mounted onv said shank, spaced; pins projecting from said: shank, anch said sleeve: having a helical contactsurface at. each end. for: engagement with one of said pins to cause rotation: of said shank when said; sleeve is moveci axially" against one. of: the pins.

HERBERT ENGEMANN;

20 nnFEnENeEs 0.1111213 The following references are of record" in the:

file of'this patent:-

UNITED. STATES PATENTS