US2003509A - Tappet - Google Patents

Description

S. JENCICK June 4, 1935.

TAPPET R k m m E Md W Wu H k A n ,m e If a 9 5 Patented June 4, 1935 uurrso STATES PATENTOFFICE Stephen Jencick, Chagrin Falls, Ohio Application November 25, 1931, Serial No. 577,354

5 Claims.

This invention relates to an improved form of tappet for use in an internal combustion engine.

As is well known to those who are familiar with the art to which the presentinvention re- 5 lates, each cylinder of aninternal combustion engine is provided with intakeand exhaust valves which are normally closed by means of a spring surrounding the stem of each valve and which are opened and closed in properly timed relation for the intake, compression, firing, and exhaust operations.

For the purpose of opening the valves, there is provided a tappet which engages the end of the valve stemin each case and which is actuated by a cam shaft so as to effect such opening of the intake and. exhaust valves in proper sequence;

but also a certain amount of noise.

Also, such improper engagement between the tappet and the valve stem results in undue wear of these parts as well as the valves and valve sets themselves; that is, any failure of the tappet to open the valve because of lack of proper operative engagement between these parts might result in the valve sticking to its seat, and failure to permit proper intake and exhaust of the gases means failure to operate in an efficient manner and hence loss of power and smooth running of the engine.

The present invention contemplates the relief of such conditions as above briefly outlined and in a general way this invention consists in the provision of an automatically adjustable tappet which is adapted to compensate for and overcome any lack of proper adjustment and engagement between the tappet and valve stem as might otherwise occur.

gardless of in spite of any sticking of the any wear between the parts and also valve or other abnormal condition which might otherwise prevail and prevent eflicient operation. I

' The present invention is so devised that the automatic contraction and extension of the tappet will be efiected in a gradual manner so as to avoid any undue clash and wear between the parts.

Another object consists in devising such an automatically adjustable tappet which can be regarded as a complete unitwhich is capable of being installed in an internal combustion engine without requiring modification of the other parts.

A further object consists in providing such a device which can bemanufactured in'a comparatively simple manner and hence sold at a comparatively low price so as to render the same practical in every respect.

Other objects will be apparent from the fol-. lowing description and claims when considered together with the accompanying drawing. 7

Fig. l is avertical sectional view illustratingthe structure and assembly of my improved form of tappet; I

' Fig.- 2 is a transverse sectional view taken on line 22 of Fig. 1; and

Fig. 3 is a vertical sectional view taken on line 3-3 of Fig. 1. In thepresent illustration, there is indicated a valve l which is of conventional form and which is arranged in the usual manner so as to close upon the valve seat 2 provided upon the engine block 3. The valve I has the valve stem 4 surrounded by the coil spring 5 which has its one end abutting the engine block while its other end engages the flanged member 6 which is se-. cured near the lower end of the valve stem 4 so as to normally force the valve I to closed engagement with the valve seat 2. The lower end of the valve stem l, as usual, extends beyond the flanged members 6 so as to provide the lower projecting end portion 4 for engagement by the upper end of the tappet. As above stated, the construction thus far described is of conventional form, as is also the cam shaft 1 and the cams 8 provided thereupon; it being understoodthat the cam shaft is operated in the same manner as is already well known to those skilled in theart.

In my present improved form of invention, the tappet comprises the casing 9 which is flanged at its lower end 9 for engagement by the cam 8 of the cam shaft. The casing 9 is hollowed-out throughout the upper portion thereof so as to receive with a drive fit the upper part I!) which has .the lower portion ll extending within the hollowed-out portion of the casing 9. Both the I formed with squared surfaces.

casing 9 and the upper part I are of cylindrical form as well as the lower portion II which fits within the casing 9. Thus, the parts 9 and I 0 are secured together and may be considered as one and the same part which may be formed as a single integral member.

The lower extending portion I I is also hollowedout with a cylindrical well adapted to receive and accommodate the coil spring I2 which rests in the bottom of the hollowed-out portion II while the upper end thereof has bearing engagement with the lower end of the wedge member I3. The wedge member I3 is also of cylindrical form and is provided at its upper side with an inclined surface extending approximately at an angle of 45, as indicated in the drawing. There is provided a companion wedge member I4 which is also of cylindrical form and whichhas its lower side provided with a corresponding, inclined surface which is adapted to engage the inclined surface of the companion member l3. The inclined engaging surfaces of the companion members I3 and I4 are of a flat or plain form sothat there will not be permitted any relativeturning movement between these companion members. The companion member I3 is practically co-terminous with the end portion I I and the lower part of the member I4 extends within the well portion II, while the upper end thereof projects upwardly into the enlarged upper portion of the part I I), as clearly indicated in Fig. 1. 7

It will be observed that the companionmembers I3 and I4 are so constructed that when they are in full engagement, as illustrated in Fig. 1, there is still space allowed between the extreme upper end of the companion member I3 and the corresponding part of the member I4 and also between theextreme lower end of the member I4 and the corresponding part of the companion member I3. This arrangement insures effective frictional engagement between these members, as will be more fully understood. It is to be understood also that the lower end of the member I3 and the upper end of the member I4 are both Thus, these two companion members I3 and I 4 may be regarded as duplicates.

The upper squared end of the member I4 is adapted to engage the under side of a shoe I5 which has its upper surface curved, as indicated at I5 so as to afford seating engagement for the eccentric member I6. The member I6 has its stub shaft I1 mounted eccentrically with respect thereto and also to one side of the longitudinal axis through the tappet assembly, as clearly indicated in Fig. 1, the shaft I! being mounted in the block I8 which is positioned within the upper enlarged hollow portion of the part IO. The bearing member I8 may rest upon a washer I8 which is of annular form and through which the companion members I3 and I4 extend.

The shoe I9,,which is a duplicate of the shoe I8, is positioned above the eccentric member I6 so as to afford seating engagement therefor with the curved surface I9 of this shoe. It should be explained that the shoe I8 is separate from the member and merely has seating engagement thereupon so as to be free for a certain degree of lateral movement as is true also of the upper shoe I9, such lateral movement being caused by actuation of the eccentric I 6.

Engaging over the upper fiat side of the shoe I9, there is provided the cap member 29 which has depending, annular llangeZD extending with frictional en agement within the upper end of upper part ID. The upper, outer surface of the member is adapted for contactual engagement with the lower projecting portion 4 of the valve stem.

The several parts of the present improved form of tappet are so constructed and arranged in assembly thatthere is afforded not only the compression of the spring I2 but also the frictional engagement between the companion members I3 and I4 themselves over their engaging, inclined surfaces as well as between the cylindrical surfaces thereof and the engaging inner surface of the well portion II. There is further frictional engagement afforded between the outer surface of the eccentric I6 and the correspondingly curved engaging surfaces of the shoes I5 and I9. Furthermore, frictional engagement is provided between the flange 20 and the inner surface of the upper end portion of the part I 8 within which this flange engages and is adapted for movement. Also, by virtue of the engagement between the upper end of the member I4 and the lower surface of the shoe I 5, as well as between the upper surface of the shoe I 9 and the inner under-surface of the member 20, there will be afforded a still further degree of friction.

The friction above referred to as being afforded between the several parts of my present tappet assembly, serves as a means of resistance which is of such degree as to prevent sudden contracting movement between the parts, but at the same time there will be permitted gradual contraction in an effective manner for the purpose intended. It is to be understood also that the spring I2, although of comparatively inferior strength, may be relied upon to gradually and effectively cause automatic extension between the parts and thus overcome the friction therebetween so as to produce the desired extension of the tappet at the time required.

As indicated in the drawing, the spring I2 is ofcomparatively smaller size and less strength than, the spring 5. Assuming, for instance, that the spring 5 has a strength of approximately eighty (80) pounds, the spring I2 in my present improved assembly may be of only approximately ten (10) pounds. However, the aggregate resistance offered by the combined factors of the spring I2 and the friction between the several parts, as above referred to, is somewhat in excess of the degree of resistance offered by the spring 5. Thus, upon actuation of the present tappet assembly by the cam shaft, this combined resistance offeredby the tappet will serve efficiently to overcome the resistance of the spring 5 so as 4 to raise the valve from its seat.

It should be explained also that the degree of rotary movement of the eccentric I6 about the axis I! is, in the present form of device, approximately ninety degrees (90) and, as will be seen from the very nature of the eccentric, the degree of resistance induced thereby through the frictional engagement thereof with the shoes I5 and I9 will be gradual. The practical effect of such manner of operation is that the automatic adjustment of the tappet assembly in either direction is gradual so as to produce a quiet and effective operation.

Upon installation of the present tappet assembly and during normal operation of the same, the spring I2 will be placed and maintained under 'a certain degree of compression by engagement of the tappet with the valve stem. This compression of the spring 52 is constant and substantially uniform and, as before stated, the

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combined resistance offered by the spring l2 and the frictional resistance between the other parts is sufficient to cause opening of the valve. The position and condition of the several parts of the present assembly, as indicated in Fig. 1, correspond to normal operation, and these parts all maintain substantially the same position and condition throughout normal opening and closing movements of the valve, the entire tappet assembly functioning as a unit. It is to be understood, of course, that during such normal operation, the upper and. lower ends of the tappet are in constantcontactual engagement with the end portion 4 of the valve stem and the cam of the cam shaft, respectively.

If, however, for any reason such, for instance, as the sticking oi the valve stem in raised or open position, or wear between the parts so as to create what would otherwise be a gap between the upper end of the tappet and the lower end of the valve stem, then the automatic adjustment of the tappet assembly is called into play.

Let us consider first the possible wear between the lower end of the valve stem and the upper end of the tappet which, as is well known, would ordinarily cause a gap with resultant noise and lack of ehiciency in the operation of the valve. Under such condition, the present tappet assembly will automatically adjust itself so as to take up such wear and to always maintain contactual engagement between the upper end of the tappet and the lower end of thevalve stem. In other words, any such wear which would ordinarily cause a gap between these parts will be compensated for by the automatic extension which will be produced by the force of the spring l2 between the extensible parts of the tappet assembly; and, as before explained, such extension between the parts of the tappet will be gradual by virtue of the frictional engagement and the action of the eccentric 16. According to Fig. 1 of the drawing with the parts in position as therein illustrated, the expanding or extending action of the spring IE will cause the eccentric 16 to turn in a counter-clockwise direction, and such operation of the eccentric I6 will produce a gradual movement and friction between the parts.

Assuming now that the valve stem, because of sticking, has caused the valve to remain in open position, ordinarily such condition would result in a decided gap between the lower end of the valve stem and the upper end of the tappet, with the objectionable result already referred to. With the present form of device, the tappet will automatically extend itself by virtue of the spring l2 so as to gradually take up what would otherwise result in such a gap. In this case, as in the other case above supposed, the extending action between the parts of the tappet will be gradual and the danger of any such gap will be obviated. That is, so long as the valve stem remains in abnormal raised position, the tappet assembly will continue in extended condition so as to at all times maintain contactual engagement between the upper end of the tappet and the lower end of the valve stem. Continued operation of the cam shaft and engagement of the cam with the lower end of the tappet, although not efiective in producing normal operation of the valve so long as the valve remains stuck in open position, yet will be permitted during such abnormal position of the valve, and continued engagement of the cam with the tappet will cause more or less compression of the spring [2 which will thereby absorb such motion of the cam shaft until it again becomes effective for normal operation of the valve. Furthermore, since such automatic extension of the tappet will compensate for and overcome any such gap which might be caused, even by such abnormal sticking of the valve stem in raised position, there is thereby always maintained a constant contactual means of engagement between the tappet and the valve stem, and the intermittent engagement of the cam with the tappet will transmit therethrough to the valve stem a certain degree of force which is calculated to assist in overcoming the sticking of the valve stem.

Then upon release of the sticking valve stem with the aid of the spring 5, the parts may again return to normal condition, and, as already indicated, the contracting movement between the parts of the present tappet assembly will be gradual by virtue of the combined component of resistance offered by the frictional engagement between the several parts as well as the force of the spring l2. This, under such condition also there is prevented any sudden movement of or between the parts and thus there is insured smooth and effective engagement and operation. It is understood, that uponrelease of a sticking valve stem so as to permit contracting movement of the tappet, the eccentric I6 will be moved in a clockwise direction, as viewed in Fig. 1. During such automatic adjustment between the parts, there will result also the same gradual and progressive increase of friction between the parts as already explained, and the spring l2 will again be placed under increased compression so as to assume condition for normal operation in the manner already explained.

With the present invention, there is obviated the necessity of manually adjusting the tappet from time to time as is now required with the present form of construction and a further ad; vantage consists in the elimination of noise be tween the parts. Furthermore, the present device makes possible a more eificient operation, as will be obvious to those who are skilled in the art. Finally, the structure contemplated by the present invention is of a comparatively simple nature, is calculated to have longer life without renewal of parts, and may be manufactured and sold at such a price as to encourage universal adoption.

Other advantages will be obvious to those who are skilled in the art to which the present invention relates.

What I claim is:

1. In a tappet assembly, the combination of a valve adapted to normally occupy closed position, a tappet comprising a plurality of longitudinally extensible, frictionally engaging parts with resilient means operatively associated therewith so as to permit contraction and effect automatic extension of the same respectively, means having a surface of regular curvature operatable as an eccentric about a center and having operative engagement with said parts for increasing the degree of friction therebetween, and means for actuating the tappet so as to open the valve and permit closing thereof, whereby there is obtained automatic adjustment of the tappet so as to maintain normal operative engagement of the tappet with the valve stem.

2. In a tappet assembly, the combination of a valve adapted to normally occupy closed position, a tappet comprising a plurality of longitudinally extensible, frictionally engaging parts and resilient means operatively associated therewith, said parts including companion members having interengaging inclined friction faces, the said frictional parts and resilient means being so co-related that there is permitted and effected gradual movement betweensaid parts in contraction and automatic extension of the same respectively, and means for actuating the tappet so as to open the valve and permit closing thereof, whereby there is obtained automatic and gradual adjustment of the longitudinally extensible parts so as to maintain normal operative engagement of the tappet with the valve stem.

3. In a tappet assembly, the combination of a valve adapted to normally occupy closed position, a tappet comprising a plurality of longitudinally extensible, frictionally engaging parts and resilient means operatively associated therewith, said parts including companion members havmg interengaging inclined friction faces, the said frictional parts and resilient means being so co-related that there is permitted and effected gradual movement between said parts in contraction and automatic extension of the same re spectively, means for actuating the tappet so as to open the valve and permit closing thereof, and eccentric means having a surface of regular curvature and having operative engagement with said parts so as to be actuated by extension and contraction of the tappet for increasing the degree of frictional engagement between the parts of the tappet, whereby there is obtained automatic and gradual adjustment of the tappet so as to maintain normal operative engagement of the tappet with the valve stem.

4. In a tappet assembly, the combination of a valve adapted to normally occupy closed position, a tappet comprising a plurality of longitudinally extensible, frictionally engaging parts with re silient means operatively associated therewith, said parts including companion members having interengaging inclined friction faces, the said frictional parts and resilient means being so co-related that there is permitted and effected gradual movement between said parts in contraction and automatic extension of the same respectively, means for actuating the tappet so as to open the valve and permit closing thereof, and means including an eccentric having a surface of regular curvature and friction shoes adapted for engagement thereby, said means having operative engagement with said parts and being actuated by extension and contraction of the tappet for increasing the degree of frictional engagement between the parts of the tappet, whereby there is obtained automatic and gradual adjustment of the tappet so as to maintain normal operative engagement of the tappet with the valve stem.

5. An automatically adjustable tappet comprising a casing having a hollow Well portion provided therein, a coil spring in said well, inversely arranged, duplicate wedge members having frictional sliding engagement with the inner surface of said well portion and having interengaging inclined faces, one of said wedge members engaging the end of said spring, a pair of friction shoes having oppositely disposed curved surfaces, an eccentric having frictional engagement between the curved surfaces of said shoes, the under side of the lower shoe engaging the end of the other of said Wedge members, a cap member having slidable engagement with the inner surface of said casing and having its under surface in engagement with the upper side of said upper shoe, said parts being so constructed and arranged that the outer surface of said cap member may engage the end of a valve stem and the opposite end of said casing may be engaged by the cam of a cam shaft, and there may be automatically effected gradual contraction and extension of the tappet in accordance with the condition of valve stem.

STEPHEN JENCICK.

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