US3118322A

US3118322A - Figure

Info

Publication number: US3118322A
Authority: US
Publication date: 1964-01-21
Anticipated expiration: 1981-01-21

Description

1964 s. OLDBERG ETAL MECHANICAL LASH ADJUSTER 2 Sheets-Sheet 1 Filed Aug. 31, 1960 FIG. 2

FIG.

FIG.4

FIG.||

FIG.IO

INVENTORS.

SIDNEY OLDBERG JOHN H. MURRAY ALVA L. SPONHAUER United States Patent corporation of Ohio Filed Aug. 31, 195i), er. No. 53,158 13 (Ilaims. (Cl. 74--586) Broadly, this invention relates to a means for adjusting and maintaining a lash free condition in a valve gear train but more specifically, pertains to a novel principle of motion disclosed in the form of a mechanical lash adjuster mechanism which functions as a means to provide the required lift loss in the cycle of operation of a valve gear train and also incorporates thereinto an adjusting means cooperable with the lift loss means resulting in an automatically adjustable mechanism eliminating any lash occurring during the operation of the valve gear train of which it is an integral part.

In units where the operation of a tappet is essential to control the proper opening and closing of a valve in regulating the amount of fluid flow in and out of a chamber associated therewith, the basic requirement rests in the lift loss function which operates to foreshorten the overall valve gear train length and accordingly, urge complete engagement of the valve with its respective seat. In providing lift loss, there is an additional requirement imposed upon the regulating tappet means whereby a lash or clearance condition resulting from over compensation by the lift loss means increases the overall length of the gear train unit and the tappet, thus, must provide additional adjustment for this lash condition. To accomplish the required lift loss provision and to eliminate the lash occurring by the foreshortening of the overall length of the mechanism, an adjustable feature is desirable. The invention which is disclosed herein is a means to accomplish the above stated purposes and to perform the function of lift loss and the provision of lash free operation in the valve gear train in a new and novel manner.

The principle of motion which is incorporated into the tappet structure can be utilized by inserting the elements thereof into a tappet or a push rod mechanism. Relative to the push rod mechanism, this involves the mere combination or" the tappet function with that of the push rod and the details of the combination are set forth later on in the specification. Therefore, the principal object of this invention is to provide a novel principle of motion incorporated into a mechanical tappet or push rod mechanism wherein the component parts thereof cooperate to control the overall valve gear train length in which the lash adjusting mechanism forms an integral part thereof.

It is another object of this invention to provide a novel mechanical tappet comprising a pair of torsional springs operable to control the rotation of a pair of component parts of the tappet whereby one of the springs provides the required lift loss per cycle of operation of the valve gear train and the other spring effects the elimination of any lash occurring therein.

t is still another object of this invention to provide a novel mechanical tappet comprising an integral screw and torsion bar component part which is cooperable at one end thereof with a rotatable tappet face member whereby these elements are relatively rotatably with respect to the body member of the unit with the torsion bar being operable to control the lift loss upon load application to the tappet with the integral screw and torsion bar component and tappet face member cooperating to eliminate lash in the valve gear train in which the elements are in integral part thereof.

It is a further object of this invention to provide a novel mechanical lash adjuster operable upon a principle ice of motion which requires relatively few component parts to effect the desired movements and accordingly, is econornically designed and readily adaptable for production.

Still further objects and advantages of the invention will be apparent from the following description taken in connection with the drawings forming a part of the specification and in which:

FIGURE 1 is a side elevational cross-sectional view of the tappet mechanism in its assembled form.

FIGURE 2 is a sectional view of the tappet mechanism taken along lines Z2 of FIGURE 1.

FIGURE 3 is an enlarged sectional view of the lead and flank angles formed between the combination screw and torsion bar member and the body member of the mechanism.

FIGURE is an enlarged sectional view of the lead and flank angles which are formed between the tappet face member and the body portion, at one end of the body portion of the tappet mechanism.

FIGURE 5 is a modification of the tappet showing the structural design wherein a cone surface is substituted for the threaded engaging surfaces formed on the body member at one end thereof and the tappet face member.

FIGURE 6 is an enlarged cross-sectional view of the cone engaging surfaces on the modified tappet illustrated in FIGURE 5.

FIGURE 7 is a cross-sectional view of a modification of the tappet structure shown in FIGURE 5 wherein the conical engaging surfaces are located at the axial end of the tappet body remote from that end which engages the tappet actuating means.

FIGURE 8 is an enlarged cross-sectional view of the cone engaging surfaces on the modified tappet illustrated in FIGURE 7.

FIGURE 9 is a sectional view of the principle of operation of the novel tappet mechanism wherein this principle is utilized in a push rod of a valve gear train mechanism.

FIGURE 10 is an analogue which illustrates the operating principle of the tappet mechanism and of the adjusting mechanism enclosed in the push rod unit.

FIGURE 11 is a side elevational view of the slot C in which the block A slides.

FIGURE 12 is a side elevational view of the slot F in which the block B slides.

Referring directly to FIGURE 1 of the drawing, the tappet mechanism It) as disclosed, comprises a substantially cylindrical body member 12 forming a chamber 14 therein. The body member 12 is designed so that one end of the chamber has an opening 16 therein while the other end has an o ening 18 in communication with the chamber and the opening 16. Each of these

openings

16 and 18 are internally threaded and adaptable to engage similarly threaded members.

Disposed in the chamber 14 of the tappet body is a combination screw and torsion bar member 2t} having an external thread 22 formed on one end portion 24 thereof forming the screw portion and adaptable to engage the threaded opening 18 of the body member 12. A recess or socket 26 is formed in the threaded end portion 24 of the combination member and is adaptable to receive one end 28 of the push rod 39 and is operable to actuate same when the valve gear train is set into motion. The other end 32 of the combination member comprises a cylindrical shaped torsion bar portion formed integral with the screw portion and structurally designed so as to have a flat sided tang 34 formed at the axial end thereof.

Engageable with the threaded opening 16 of the tappet body is a tappet face member 36, also illustrated in FIG- URE 2, which has an externally threaded end portion 38 thereon being operable to engage the internally threaded opening 16 of the body member and provide a threaded interface 39 therebetween. The tappet face member has an opening 40 formed in the central portion thereof which extends into the tappet face member a depth substantially greater than the required distance of travel of the combination member to provide lift loss to the valve mechanism and further opens in a direction inwardly towards the chamber 14. This opening is adaptable to receive the tang 34 formed at the end of the torsion bar portion of the combination screw and torsion bar member and by the dimensioning of the opening and the tang, when inserted into the opening, the combination and tappet face members are cooperable for conjoint rotation. The tappet face member has a base portion 42 thereon which is engageable with an actuating means (to be described later) forming a part of the valve gear train. A torsionally preloaded coil spring 44 is disposed within the tappet body and is located in the tappet chamber 14. One end 46 of the coil spring is secured to the tappet body through an opening 48 while the other end 50 is engageable with one of the series of slots or spaces 52 (more clearly illustrated in FIGURE 2) provided in the tappet face member and which are circumferentially disposed about one peripheral end portion of the tappet face member. These slots are so arranged that the end portion 50 of the spring can be disposed into any one slot without difliculty in the assembly of the unit.

The tappet structure is housed and restricted to a reciprocatory motion by the dimensions of the bore (not shown) into which it is placed.

The bore is formed in a housing or structure which, for example, would be part of the engine block of an internal combustion engine. The push rod 30 as above referred to and partially disclosed in the drawing of FIGURE 1, forms a part of the valve gear train system and for exemplary purposes, is operable upon actuation to move a rocker arm (not shown) in an overhead valve type engine which in turn, will impart a reciprocatory motion to the valve stem (not shown) and thereby open and close the porting which controls the flow of fluid in and out to the chambers of the internal combustion engine. The means to impart this reciprocatory motion is as follows. A cam member 54 is fixed for rotation with a camshaft 56 whereupon the cam structure has a rise 58, a fall 60 and a dwell 62 surface portion thereon predicated upon the direction of rotation of the cam and shaft which is clockwise as illustrated. These surfaces are operable to engage the base portion 42 of the tappet face member 36 thereby actuating the tappet mechanism accordingly. Rotation of the shaft 56 imparts rotation to the cam which abuts the base portion 42 of the tappet face member and accordingly, on the rise portion 58 of the cam 54, the tappet is moved in an upward direction which in turn will impart the same movement to the push rod and the valve stem of the train. In this upward direction of movement, an axial load is imposed upon the tappet mechanism which brings about the functioning of the above referred to internally threaded and externally threaded members forming a part of the tappet mechanism.

To more fully understand the inter-relationship of the elements of the mechanism, a typical operating sequence is set forth therein as follows.

Upon rotation of the cam and shaft members in a clockwise direction, the rise portion 58 on the cam surface imparts an upward movement to the tappet whereby the combination screw and torsion bar member 20 transmits this direction of motion to the push rod 30 at the

engaging portions

26 and 28, respectively, and a load is thus imposed on the tappet mechanism. Continued rotation of the cam on the rise 58 increases the applied load and effects a downward clockwise rotation of the screw portion 24 within the threaded opening 18 of the body 12. It is to be noted that when the tappet assembly is on the cam rise 58, the engine valve is being opened against the resistance of a valve spring which urges the valve to a closed position. In overcoming the force of the valve spring,

friction loading between face member 36 and body 12 at threaded interface 39 is built up to sufficient magnitude to prevent relative rotation between face member 36 and body 12 when torsion bar 32 attempts to unwind at the lower end. Continued rotation of the screw portion effects a torsional load in the torsion bar portion 32 of the combination member, since the tang 34 thereof is rotatably locked to the tappet face member 36. This downward movement of the combination member provides lift loss to the valve gear train.

Further rotation of the cam effects engagement between the base of the tappet face member and the fall surface portion of the cam, gradually reducing the load imposed on the combination member. Because of the relationship between the threaded engaging surfaces between the tappet body and the screw portion of the combination member, the tappet body and the tappet face member, relative rotation will occur first between the tappet body and the tappet face member. Therefore, the torsion bar portion will unwind, releasing the torsional load therein and effect clockwise rotation of the tappet face member.

The clockwise movement of the combination member and the tappet face member results in an overall foreshortening of the tappet length whereby the difference in the axial movement of the members due to the difference in the lead angle of the threaded surfaces is absorbed by the opening 40 in the tappet face member. This foreshortening of the tappet length creates a lash condition in the valve gear train which is undesirable. At such time when the cam dwell surface 62 engages the tappet face member base, the maximum clearance is achieved and a no-load condition is reached. In compensating for the lash condition, torsionally preloaded spring 44 which has been additionally loaded by the clockwise rotation of the tappet face member, will unwind and impart a counterclockwise rotational movement to the tappet face member. The movement of the tappet face member will in turn impart a counterclockwise movement of the combination member through the locking engagement of the tang in the opening 40 of the tappet face member. The net effect of this relative movement of the members results in the extension of the overall tappet length, thereby eliminating the clearance in the valve gear train.

Referring back to the operational sequence of the tappet mechanism, in the axially loaded condition, a downward or clockwise rotation of the screw portion 24 of the combination member occurs, providing lift loss in the gear train whereby the threaded angular relationship of the external thread on the combination member and the internal thread on the body member are essential to any movement of the combination member 20. FIGURE 3 is a partial or sectional view of the threaded angularity which exists between the two members. The flank angle 0 is disclosed in FIGURE 3 as being 30 and is a standard angle suggested by American Standard threadforms.

The lead angle of the screw portion is disclosed as being 16 and the flank angle, as above mentioned, is 30. In determining the optimum values of the flank angle 0 and the lead angle on the screw portion 22 and the cooperating angles on the body internally threaded portion 18, several variables must be considered. The lead angle on the screw member must be a nonlocking angle so that the axial load applied at one end of the screw portion will allow the rotation thereof under the influence of this load. As the flank angle is increased upwardly from 0, there is a definite increase in the locking action between the two threaded members and to compensate for the flank angle increase, there must be a proportionate increase in the lead angle of the screw. Lead angle values depending upon the material used, vary considerably. In steel on steel applications, lead angles have been successfully utilized in a range of 11 to 24 but for optimum results, has been determined to be about 16 where the flank angle is a standard American thread form and is in this example, 30. When the upper portion of torsion bar 24 is rotated under axial loading, it is necessary that locking engagement be maintained at threaded interface 39 between the body portion 12 and the tappet face member 36. This locking relationship is essential to allow the torsion bar portion 32 to be wound by the rotation of the screw whereby the tang 34 secured in a non-rotative manner relative to the tappet face member, operates to hold one end of the torsion bar and thus a torsional spring load is created therein.

The spring rate of the torsion bar 32 is determined by the required lift loss per cycle of valve gear train operation and is a function of the maximum axial load applied to the system including the lead and flank angles between the combination member and the body member and the co-efiicient of friction existing between the members. If a relatively large lift loss per cycle of valve operation is required, low values of the spring rate would be necessary to allow more windup for a given axial load, lead and flank angles and the co-efiicient of friction numerical values. The minimum value of the spring rate would be based upon the stress limitations of the spring material while the maximum value would be based upon that anuount which would allow some finite lift loss per cycle of valve operation.

When the maximum axial load is applied to the screw member, the variables comprising the radius of the screw portion R the lead and flank angles of the screw portion illustrated in FIGURE 3 and the frictional co-efiicient between the screw portion of the combination member and body member at the threaded contacting surfaces, and the further variables relative to the relationship of the lead angle and the flank angle 0 illustrated in FIGURE 4, of the lower thread engagement between the body and tappet face member at the threaded surfaces of opening 16 and tappet face end portion 38, respectively, the radius of the tappet face member R and the friction co-efiicient depending on the material used, occurring between these two elements must all be determined and compensated for accordingly.

The determination of the optimum flank angle 0 and the lead angle of the threaded engagement between the tappet face and body members is based upon the required torsional locking force necessary therebetween to resist relative movement. The lead angle of the threaded end portion 38 on the tappet face member, as disclosed in FIGURE 3, is about 4 based on a steel on steel material application. This angle is determined by the above mentioned variables and is the angle at which the required locking torsional force can be adequately maintained between the tappet face member and the tappet body and still avoid a self-locking relationship which exists between the engaging threaded surfaces. The flank angle illustrated and disclosed in FIGURE 4 has been determined to be about 68 for optimum results and as such, is coupled with the lead angle of 4 to coordinate and resolve the above variables into the optimum operating structure.

In the development of the optimum lead angle 0 a range of between 0 and as high as was found to be operative. At the 0 lead angle, we have in effect a cone relationship where the co-efdcient of friction between the two elements thus becomes the most important factor to be considered. (This will be described later in detail when the modification of the invention as set forth and disclosed in FIGURES 5, 6 and 7 of the drawing and will be described later in detail.) For the purposes of discussing the tappet structure disclosed in FIGURE 1, the optimum lead angle of 4 will be considered. Thus, with this lead angle at 4 and the flank angle at 68, the tappet mechanism will remain rotatably fixed between the tappet face member 36 and tappet body 12 at the threaded opening 16 thereon when the maximum axial load has been applied to the screw portion of the combination member and accordingly, the torsion bar portion 32; will wind up when the cam actuating movement is at the top of the rise 58 in the cam structure.

The tappet face member base portion 42 upon engaging the fall surface 66 of the cam, results in the reduction of the axial load imposed upon the combination member 29. The low lead angle 5 on the tappet face member coupled with the hi h flank angle 0 affects the tappet operation as follows. The reduction of axial force on the tappet structure through further rotation of the cam, releases the locking action occurring between the tappet face and body members at a higher value than is necessary to relieve the locking action between the combination member at the threaded engaging portions 22 on the screw portion 26 and at opening 18 of the body member. Thus, the lead angle and flank angle 6 will release their locking engagement when the load is partially reduced from the tappet body whereby it takes a substantially greater reduction of load on the tappet to cause the screw portion 24 to rotate within the threaded opening 18 of the tappet body. The above rotation is induced accordingly by the spring windup of the torsion bar portion of the combination member. Therefore, with this relationship of the lead and flank angle between the tappet face member and tappet body, the combination screw and torsion bar member and the tappet body, the energy stored in the torsion bar will be released by the clockwise rotation of the torsion bar tang portion 34- and in turn, the clockwise rotation of the tappet face member 36 with respect to the body member 12.

The relative rotation between the tappet members is determined by the energy stored in the torsion bar and the axial overall length of the tappet member is also based upon the relationships of the lead angles. Rotation of the screw member with a lead angle of 16 will cause a greater reduction the overall tappet length than the rotational movement of the tappet face with a lead angle of 4 tending to extend the tappet length. The net reduction in the tappet overall length thus is the difference between the axial movement of the combination screw and torsion bar member and the tappet face member.

When the coil spring 44 is assembled into the tappet mechanism, the arrangement is such that it is desirable to have this spring in a preloaded condition. The spring rate is predicated on an amount which must not be too great to resist the spring rate of the torsion bar in its effort to unwind but in effect, the coil spring acts as a means to maintain the tappet body and the tappet face in a locking position along with the lead and flank angles thereof.

In this preloaded condition, upon rotation of the tappet face member at the load releasing stage of operation, there is an additional torsional load imposed on the coil whereupon the spring return rate is increased thereby. If the lift loss provided for by the rotation of the combination element is too great and accordingly results in excessive clearance or lash in the "ear train mecha nism, it is essential that this lash condition be corrected. Therefore, in compensating for this additional clearance effected by the excessive clockwise rotation of the tappet face member 36, the coil spring 44 will, upon sensing that there is a release of the axial restriction thereon, rotate the tappet face member in a counterclockwise dircction partially releasing the torsional spring energy stored therein. When this occurs, there is a corresponding movement in the combination screw and torsion bar member due to the tang 34 of the torsion bar portion being disposed into the opening 40 of the tappet face member. Thus, when the coil spring rotates the tappet face member, the lead angle on the tappet face member will again cause a very limited amount of foreshortening of the tappet overall length but the lead angle p of the combination member 2t) will compensate for this foreshortening and the end result will be an overall extend- 7 ing of the tappet length, thereby eliminating the lash condition.

The operation of the tappet mechanism as disclosed in FIGURE 1 is based upon the principle which is disclosed in the analogue illustrated in FIGURE 10. This principle of operation has been utilized in the tappet mechanism of FIGURE 1 and the tappet mechanisms of FIGURES 5 and 7 and the push rod of FIGURE 9 which will be described later in detail.

The operation of the analogue is as follows. Upon load application, represented by P, to block A, block A slides relative to block B along the slot C formed therein. Because of the degree of angularity of lead angle and the flank angle illustrated in FIGURES 10 and 11, respectively, a locking relationship exists between the block B and the base member D. The flank angle 0 and the lead angle existing between block A and block B is determinable as being operable to allow relative movement between block A and B upon load application to block A. This sliding movement of A causes the coil spring E to be compressed and this spring therefore is compressively loaded by the movement of block A. When the load P is partially released, the lead angle s, and the flank angle 6 are calculated such that relative movement between A and B will occur before there has been a sliding movement between block B and base member D in slot F formed in D which is induced by the spring rate of coil spring E. This movement between B and D is predicated on the lead angle (p and the flank angle 0 and is designed such that upon release of the load applied to block A, the amount of reduction of this load will cause an unlocking reaction resulting in relative movement between the members B and D before there will be any sliding movement between A and B. Thus, the coil spring E inducing the movement of B and accordingly, A with respect to D, expands and releases the torsional load imposed thereon. The coil spring G being of a lower spring rate than spring E, upon movement of block B relative to base block D, is thereby placed in tension. Upon complete release of any axial loading on block A by the force P, spring G contracts and causes B to move to the left relative to the base member D. Due to the difference in spring rates, the movement of block B will cause block A to slide upwardly in the slot C and accordingly, return the unit to the original position prior to the load application of P.

The elements of this analogue can be readily substituted into the tappet mechanism as above disclosed, and accordingly, the same action or movement can be utilized to provide the lift loss and lash adjusting features instructure disclosed in FIGURES 5 and 7. The basic 1 changes imposed and provided in FIGURES 5 and 7 relate primarily to the lead and flank angles between the body and tappet face members. As can be seen in the drawing, FIGURES 5 and 7 thereof, the lead angle is 0 while the cone or flank angle 0 has been increased to the point where a locking action can be maintained between the relatively rotatable members.

The members of the structures disclosed in FIGURES 5-9 are identified with the reference characters used in FIGURE 1 including the additional characterization of a prime and double prime where the parts thereof correspond in design and function. The operating function of the tappets 10' and 10 is identical to that operation performed by the mechanical lash adjuster tappet discolsed in FIGURE 1. The flank and lead angles have been designed where the provision of a lead angle has been substituted for by the increase of the co-efficient of friction variable between the tappet body 12' and the tappet face member 36' of FIGURE 5 and the tappet body 12" and threaded member 64 of FIGURE 7. The

coefficient of friction coupled with the flank angle 0 illustrated in FIGURE 6, formed between the two members react to impart a locking action relative to these two members upon load application through a cam member and push rod member (not shown) to the combination screw and torsion bar member of the tappet structure of FIGURE 5. When the lead angle is 0, the variable of the co-eflicient of friction becomes important as a determining factor for the locking relationship between the tappet body 12 and face member 36. A high coefficient of friction between the two elements will maintain a locking action therebetween upon load application but the basic function of the tappet face member is to provide the necessary rotative force to return the torsion bar and screw member to its original or nearly original length to compensate for any lash occurring when the lift loss requirement has been met. The flank angle 0 has been determined to be at a maximum at about 75. At this angle, there is a self-locking action between the two members and it is undesirable due to the elimination of the adjusting feature. But with the flank angle somewhat reduced, relative rotation is possible between the two elements and the coefiieient of friction must be maintained therebetween to insure the continued reaction of the elements to provide the desirable tappet adjusting features. Therefore, the lead angle of the screw portion 24' of the combination member is the only angle which determines the amount of foreshortening or overall lengthening of the tappet structure and can be adjusted accordingly, based upon the required lift loss for the system.

The tappet structure as disclosed in FIGURE 7 is similar in structural design to the tappet design in FIGURE 5 with the exception that the cone surfaces are located between the one end of the body member 12 remote from the cam engaging surface 42 and a rotatable internally threaded member 64 which houses the combina' tion screw and torsion bar member 20". The operating function of this tappet structure is identical with that of FIGURE 5 and the basic difference rests in the arrangement of the cone engaging surfaces forming flank angle 0 illustrated in FIGURE 8, with respect to the body member 12" and the combination screw and torsion bar member 20".

A typical operating cycle of the units of FIGURES 5 and 7 is as follows. Upon rotation of the actuating cam member (not shown in FIGURES 5 and 7) to the rise portion thereof, the tappet body member 12 will be moved axially in an upward direction. The end portion of the push rod (not shown in FIGURES 5 and 7) disposed in the socket 26' and 26" of the combination screw and

torsion bar member

20 and 20 imposes an axial load on the combination member causing the

screw portion

24 and 24" to rotate clockwise in the threaded

portion

18 and 18 of the body 112' of FIGURE 5 and the threaded member 64 of FIGURE 7. The clockwise rotation of the screw torsionally winds up the

torsion bar portion

32 and 32" of the combination member 20' and 20" since the

tang

34 and 34 on the one end thereof is inserted into the opening and 40" of the tappet face member 36' of FIGURE 5 and a body insert portion 66 of FIGURE 7 preventing relative rotation therebetween. This torsion bar windup is predicated on the desired lift loss required for the system and accordingly provides this function. Locking engagement preventing relative rotation between the body member 12' and the tappet face member 36 of FIGURE 5 and the body member 12" and threaded member 64 of FIGURE 7 is maintained through the angularity of these faces and the frictional co-eiiicients existing therebetwcen.

Upon further rotation of the cam to the fall and dwell portions thereof, the axial load imposed on the tappet mechanism through the combination member is relieved whereby the

torsion bar portion

32 and 32 unwinds 9 causing clockwise rotation of the tappet (face member 36' of FIGURE and the body 112 of FIGURE 7.

The clockwise movement of these members is effected due to the relationship of the lead and flank angles of the combination member and the body and threaded member with respect to the relationship of the engaging cone surfaces forming flank angle 6 of FIGURE 6 and flank angle 6 of FIGURE 8. As designed, the axial load release will cause rotation between the cone engaging surfaces, due to the unwinding torsion bar, before rotation will occur between the engaging body threaded portion and the screw portion of the combination member.

If the lift loss provided by the windup of the torsion bar has created clearance or excessive lash in the valve gear train, the coil spring $4 and 44" secured at one end to the body member and at the other end to the rotatable member of the cone engaging combination is utilized. The spring is preloaded when assembled and is additionally loaded by the relative rotation between the cone engaging members. Thus when the lash condition exists the spring 44 and 44- tends to expand or unload due to its resilient nature causing the tappet face member '36 of FIGURE 5 and the body member 12 of FIGURE 7 to rotate back in a counterclockwise direction. Because of the securement of the

tang

34 and 34 of the torsion bar portion 3 2' and 32" with the tappet face and body members, any movement of these members causes a similar movement in the combination screw and torsion bar member. Thus the rotation of the tang causes the screw portion of the combination member to rotate up into cont-acting engagement with the push rod end portion in the socket 2rd and 26 thereof.

The novel motion transmitting principle can also be utilized in a push rod structure Where the features of automatic lash adjusting and lift loss are incorporated into the push rod construction and functions to accomplish the above stated purposes. In this construction, as shown in FIGURE 9, the combination screw and torsion bar member 68 threadedly engages a body member 70 upon the application of a load to the end portion 72 of the combination member. The cone surfaces 74 are formed between the upper portion 76 and the lower cam engaging portion '78 of the body member whereby the torsion bar portion fit} of the combination member is disposed in chamber 82 formed by the body and has one end 84 thereof secured to the lower portion 78 of the body by a pin member 86. The combination member will rotate in accordance with the relationship of the load application and release in an identical manner to that of the tappet structures shown in FIGURES 1, 5 and 7. The torsion spring 83 located in the body chamber 82 has one end thereof secured to the portion 78 with the other end secured to a block or guide member 9% disposed in the chamber 82 and operates in the identical manner to the coil springs 44, 44- and 44" illustrated in the previous designs and functions to maintain the no lash condition between the actuating means (not shown) in contact with the push rod and the rocker arm or similar structure to which the one end 72 of the combination element is in contact therewith.

Thus, in m operating sequnce, upon load application, the combination member 68 will rotate in a clockwise direction providing the necessary lift loss in the valve gear train and the cone surfaces 74 are angularly disposed where there is a self-locking condition maintained by this angularity and the co -efficient of friction existing therebetween. The frictional co-efficient variable is again important in this structure as it is in tappets of FIGURES 5 and 7 and functions to maintain the maximum possible torque resisting force and still provide relative rotation therebetween upon load release. Thus, when the load is released from the combination member 68, the torsion bar, in the wound condition, will be allowed to return to the unwound condition correspondingly rotating the lower portion 78 of the body and thereby compensate for the necessary lift loss. In the event that the lifit loss is more than what is necessary to insure valve closing, the torsion spring 83 again functions to rotate the lower portion in a counterclockwise member. The linkage including the pin 86 formed by the securement of the torsion bar with the lower portion '78 of the body member rotates the combination member in a counterclockwise direotion effecting relative movement between the combination member and the body member tending to increase the overall length of the push rod construction based on the lead angle formed between the threaded portions of these members. This arrangement thereby eliminates the lash occuiring between the elements of the valve gear train and the entire unit is maintained in a lash-free condition.

It can be seen from these various modifications that the basic principle of operation of the tappet structure disclosed in FIGURE 1 can be utilized effectively to accomplish the same basic purposes. The provision of a lead angle between the lower portion of the tappet body and the tappet face member between the range Olf O and 10 \is a variable which is compensated for by the relationship of the variables between the lead angles and the flank angles involved in the relatively rotatable members. The utilization of at 6 lead angle on the cone engaging surfaces of he modifications does not vary or alter the principle of operation but merely eliminates the lead angle variable and introduces the importance of the co-efiicient of friction between the elements. Therefore, it can be seen that the relatively rotatable members having the cone surfaces thereon function in the identical manner with the tappet structures having a lead angle and a corresponding flank angle associated therewith. The basic functioning of all of these units as disclosed does not Vary or alter the overall effects but merely are parameters that must be compensated for and further, can be varied within certain limits to successfully provide the desired motion which accomplish-es the basic purposes of a mechanical lift loss provider and lash adjuster.

While the present invention has been described in connection with certain specific embodiment, it is to be understood that the foregoing description is merely exemplary and that the concept of this invention is susceptible of numerous other modifications, variations, and applications which will be apparent to persons skilled in the art. The invention is to be limited, therefore, only by the broad scope of the appended claims.

What we claim is:

l. A variable length lash adjuster adapted to receive a load, comprising first and second relatively movable members, said first member having inclined-plane bearing means thereon with said second member having follower means thereon engaging said inclined-plane bearing means of said first member, a third member frictionally engageable with said first member, said second member being movable along said inclined-plane bearing means relative to said first and third members thereby varying the length of said adjuster, a first resilient means forming a part of said second member and cooperable with said th ld member to transmit actuating force to said third member to shorten said adjuster and a second resilient means operatively associated with said third member to transmit actuating force to said third member to cause a lengthening of said adjuster.

2. A variable length lash adjuster adapted to receive a load, comprising first and second relatively movable members, said first member having inclined-plane bearing means thereon with said second member having follower means thereon engageable with said inclined-plane bearing means of said first member, a third member frictionally engageable with said first member, said second member being movable along said inclinedplane bearing means and relative to said first and third members for varying the length of said adjuster, in a first resilient means forming a part of said second member and cooperable with said third member to transmit actuating force to said third member upon load release, and a second resilient means operatively associated with said third member to transmit actuating force to said third member upon load release and subsequent to the effective actuation of said first resilient means.

3. A mechanical lash adjuster adapted to receive a load, comprising first and second members, said first member having threaded portions thereon, said second member having threaded portions thereon cooperable with said threaded portions of said first member, said second member having a torsion bar means forming a part thereof, a third member, said third member being frictionally engageable with said first member and being rotatably fixed to said torsion bar means, said second member operable to slide on said first member effecting a foreshortening of said adjuster upon load application, said third member being restricted in movement by said first member upon load applications, causing torsional windup in said torsion bar means and additional resilient means fixed to said first member and said third member effecting movement in said third member under no load conditions causing movement in said second member effecting an increase in the length of said adjuster.

4. A mechanical lash adjuster adapted to receive a load, comprising a pair of relatively movable members, said members having cooperating bearing and follower inclined-plane surfaces thereon effecting relative movement therebetween upon load application, a third member, one of said pair of members having resilient means thereon engageable with said third member operable to resist a predetermined load and effecting movement to said third member under a no-load condition, said third member rotatably fixed to said resilient means and frictionally engageable with the other of said pair of members, said third member having a bearing surface thereon engageable with a bearing surface on the other of said pair of members whereby said engagement effectively limits relative movement therebetween upon load application, and additional resilient means operatively associated with said third member to impart movement to said third member subsequent to the effective movement imparted by said first mentioned resilient means.

5. A mechanical lash adjuster adatped to receive a load, comprising a pair of relatively movable members, said members having cooperating bearing and follower inclined-plane surfaces thereon effecting relative movement therebetween upon increased load application causing a foreshortening of the adjuster length, a first resilient means forming a part of one of said members of said pair and effective to limit relative movement thereof with the other member of a third member, said pair, said first resilient means cooperable with said third member and being rotatably fixed thereto effective to actuate said third member upon a decreasing load application, said third member being frictionally engageable with the other member of said pair and being restricted in movement by said engagement upon increased load application and relatively movable therewith upon a decreasing load application, a second resilient means fixed to said third member and said other member of said pair effecting movement to said third member under no-load application causing an increase in the adjuster length.

6. A mechanical lash adjuster adaptable to receive a load, comprising first and second relatively rotatable members, said first member having an inclined-plane bearing surface thereon with said second member having a follower surface thereon engageable with said inclinedplane bearing surface of said first member effecting relative movement therebetween in a downhill direction upon load application and decreasing the length of said adjuster, said second member having a torsion bar portion forming a part thereof, a third member engageable with said torsion bar portion, said third member being frictionally engageable with said first member and upon load application being rotatably fixed thereby effecting torsional windup in said torsion bar portion of said second member, a resilient means fixed to said third member and said first member, said torsion bar portion imparting movement to said third member in an outward direction from said first member upon decreasing load application effecting a torsional windup of said resilient means, said resilient means effecting movement to said third member to an inward direction toward said first member and to said second member in an uphill direction upon no-load application causing an increase in the adjuster length.

7. A mechanical lash adjuster according to claim 6 wherein said inclined-plane bearing surface on said first member and said follower surface on said second member comprising engageable threaded portions having a lead angle in the range of 11 to 23 with a corresponding flank angle of about 30 and said engagement between said first member and said third members comprising a threaded contacting relationship wherein said threads comprise a lead angle in a range of 2 to 11 with a corresponding fiank angle of about 68.

8. A mechanical lash adjuster according to claim 7 wherein said lead and said flank angles are predetermined proportionate to the applied load and wherein said lead angles are determined by said flank angles.

9. A mechanical lash adjuster according to claim 7 wherein said threaded portions between said first and second members comprises a lead angle of about 16 with a corresponding flank angle of 30 and said threaded relationship between said first and third members eomprises a lead angle of about 4 with a corresponding flank angle of about 68.

10. A mechanical lash adjuster adapted to receive a load comprising a body member having a threaded bearing surface thereon, a combination member having a cooperating threaded follower surface thereon, a tappet face member frictionally engageable with the body member and engageable with the combination member, said combmation member comprising a torsion bar portion having one end thereof rotatably fixed to said tappet face mem her, said threaded cooperating surfaces being operable to provide relative movement between said body member and said combination member upon load application to said combination member, said combination member operable to effect a torsional windup of said torsion bar portion upon movement relative to said body member, said torsion bar imparting rotative movement to said tappet face member to effect an increase in the overall adjuster length upon decreasing load application, a resilient coil spring fixed to said tappet face member and said body member effective to control the relative movement between said members, said coil spring imparting rotative movement to said tappet face member effecting movement of said tappet face member upon no-load application increasing the adjuster length.

11. A mechanical lash adjuster according to claim 10 wherein said body member has an inclined-plane bearing surface thereon frictionally engageable with a corresponding inclined-plane bearing surface on said tappet face member in a non-locking angle relationship.

12. A mechanical lash adjuster according to claim 10 wherein said body member has a threaded surface thereon frictionally engageable with a cooperating threaded surface on said tappet face member whereby said resilient torsion bar portion of said combination member and said resilient coil spring member being operable to impart rotative movement to said tappet face member effecting relative movement between said members increasing and decreasing the adjuster length.

13. In a lash adjuster adapted to receive a load and assume an adjusted length, means comprising a first member including a first camming portion and a second member including a carnming portion operatively associated with said first camming portion and being operative in response to an axial force imposed by the load to eifect relative rotational and axial movement of said second member With respect to said first member, means comprising a second camming portion on said first member and a third member including a camming portion operatively associated with said second carnming portion and being operative in response to a torsional force to effect relative rotational and axial movement or" said third memher with respect to said first member, said second member including torsionally resilient means engaging said third member and being operative during the application of said axial force for storing torsional energy in said torsionally resilient means releasable in response to a predetermined decrease in the load to effect said relative rotational and axial movement of said third member with respect to said first member to shorten said adjuster below the adjusted length and resilient means engaging said first and third members operable in response to a load releasing condition to eflect relative rotational and axial movement of said second and third members with respect to said first member to increase the length of the adjuster to the adjusted length.

References Cited in the file of this patent UNITED STATES PATENTS 1,193,913 Manning Aug. 8, 1916 2,283,536 Burkhardt May 19, 1942 2,433,089 Burkhardt Dec. 23, 1947 2,694,389 Turkish Nov. 16, 1954

Claims

1. A VARIABLE LENGTH LASH ADJUSTER ADAPTED TO RECEIVE A LOAD, COMPRISING FIRST AND SECOND RELATIVELY MOVABLE MEMBERS, SAID FIRST MEMBER HAVING INCLINED-PLANE BEARING MEANS THEREON WITH SAID SECOND MEMBER HAVING FOLLOWER MEANS THEREON ENGAGING SAID INCLINED-PLANE BEARING MEANS OF SAID FIRST MEMBER, A THIRD MEMBER FRICTIONALLY ENGAGEABLE WITH SAID FIRST MEMBER, SAID SECOND MEMBER BEING MOVABLE ALONG SAID INCLINED-PLANE BEARING MEANS RELATIVE TO SAID FIRST AND THIRD MEMBERS THEREBY VARYING THE LENGTH OF SAID ADJUSTER, A FIRST RESILIENT MEANS FORMING A PART OF SAID SECOND MEMBER AND COOPERABLE WITH SAID THIRD MEMBER TO TRANSMIT ACTUATING FORCE TO SAID THIRD MEMBER TO SHORTEN SAID ADJUSTER AND A SECOND RESILIENT MEANS OPERATIVELY ASSOCIATED WITH SAID THIRD MEMBER TO TRANSMIT ACTUATING FORCE TO SAID THIRD MEMBER TO CAUSE A LENGTHENING OF SAID ADJUSTER.