US2689557A - Poppet valve - Google Patents

Description

Sept. 21, 1954 w. H. TAYLOR POPPET VALVE 2 Sheets-Sheet 1 Filed July 22. 1953 W. H. TAYLOR POPPET VALVE Sept. 21, 1954 2 Sheets-Sheet 2 Filed July 22. 195s f2 lill/IW INVENToR. Mza@ JV. 71E7 4- BY -h-nc Patented se. 21, 1954 UNITED STATES PATENT OFFICE POPPET VALVE William H. Taylor, Mentor-on-the-Lake, Ohio Application July 22, 1953, Serial No. 369,657

This invention relates to poppet valves, and to poppet valve, guide, and seating spring combinations, and is an improvement on the valve and combination described and claimed in my prior Patent No.` 2,658,492 issued November 10, 1953.

The valve disclosed in the above entitled application operates very satisfactorily when properly installed, but since its stem is readily elongatable elastically and can be elongated by the applied force of the seating spring, its cannot be installed by following the customary procedures.

In installing a set of conventional poppet valves, the customary procedure is to place all of the valves in their guides in seated position, then to install the seating springs, and then, by em ploying the usual feeler gauge, to adjust the tappets successively for the proper clearance. The tappet clearance is usually'adjusted by turning the engine so that each tappet in turn is disposed in its lowermost operating position and while it is in this position, adjusting the tappet head endwise of the valve stem until the desired clearance between the head `of the tappet and the bottom end of the valve shank is obtained,

The garage mechanic being familiar with the foregoing procedure, is apt to attempt to install the valve of the above identified application in the same manner unless speciiically forewarned not to do so. The seating spring, being stronger than the spring forming the elongatable stem of the valve of the above identified application, will elongate `the stem far beyond the amount desired and often to such an vextent `as to result in destruction of the valve unless the elongation is limited in some manner.

For example, assuming such a valve to be seated and the tappet to be moved downwardly to its lowermost operating position with the tappet head at its lowest adjusted position, the clearance then is much greater than the norn mal operating clearance for the conventional valve. If a seating spring then is installed, it will elongate the stem of the valve to the extent necessary to dispose the lower end of the shank in contact with the upper end of the tappet. This elongation would be far too great for proper timing and might result in imparting a permanent elongation to the valve stem.

Again, if the valve of the above application is 8 Claims. (Cl. 12S-188)` installed with the tappet in a more elevated i position when the seating spring is installed, the mechanic is apt to lower the tappet to its lowermost position by turning the engine and then to attempt to adjust the tappet head to a lower position for obtaining the usual clearance between the lower end of the valve stem and the upper end of the tappet head. Such procedure will result in the same unsatisfactory conditions.

This characteristic of the valve of the above identified application makes the installation of all the seating springs before adjustment of the tappets impractical.

To overcome these diiliculties and dangers and to make possible the proper installation of` a valve having a readily elongatable stem by following the installation procedure ernployed for conventional valves, provision is made in accordance with the present invention to limit the elongatability of the stem by a lost motion `means while permitting a predetermined desired elongation for operation so that, after installation of the seating spring, the tappet head may be completely withdrawn from beneath the valve withoutcausing undue elongation of the stem by the seating spring.

Preferred means for accomplishing this purpose are illustrated in the accompanying drawings, in which:

Figure l is a sectional View through a portion of an automobile engine showing a valve, valve guide, tappet, and seating spring combination embodying the principles of the present invention, the valve and tappet being shown in elevation for clearness in illustration;

Figure 2 is a longitudinal sectional view through the valve illustrated in Figure 1 and is taken on line 2 2 thereof, part of the valve being shown in elevation for clearness in illustration;

Figures 3 and 4 are longitudinal sectional Views partly in elevation and similar to Figure 2 showing two operating positions of the parts of the valve itself;

Figure 5 is an enlarged fragmentary longitudinal sectional view of a portion of the valve, taken at a right angle to the view illustrated in Figure 2; and

Figures 6, 7 and 8 are longitudinal sectional views, similar to Figure 1, illustrating modified forms of the valve, respectively.

Referring to the drawings, there is illustrated a portion of an internal combustion engine including an engine block I, a piston 2, a valve port 3, and a bore in which the usual valve guide 4 is accommodated, the port 3 illustrated being either an exhaust port `or an intake port. The block has the usual water jacket 5 which surrounds the cylinder and the portion of the block through which the bore for the valve guide 4 extends. The engine also includes a conventional adjustable tappet or valve lifter 5.

For purposes of illustration, the tappet is' shown as one of the reciprocable types having a head portion 'I adapted to engage and lift the Valve from its seat, the head being in screw threaded engagement with the body of the tappet so as to be adjustable axially of the valve to be operated thereby. The structure thus described is conventional in automobile and other internal combustion engines, though in some inistances the water jacket is omitted and pro vision is made for air cooling the various parts of the block, and in others the valve tappet is in the form of a rocker arm.

rShe valve, with which the present invention is particularly concerned, comprises a head 8 adapted for cooperation with a seat surrounding the port 3, a stem 9 adapted to be received in the valve guide 4 by which it is supported and guided for axial reciprocation, and a shank Io adapted to receive the usual locking collar II and keeper I2 for connecting a seating spring I3 to the valve. The lower end of the shank lil of the stem is adapted to be engaged by the upper surface of the adjustable head 'I of the tappet 5 for lifting the valve and releasing the valve for return by the seating spring I3.

The valve stem 9 is installed in the guide with a slight drag fit. It is axially elongatable and is in the form of a closed coil spring connected at one end to the head portion 8 in xed coaxial relation thereto and at the other end to the shank IQ.

In accordance with the present invention, lost motion connecting means are provided for limiting the elongation of the stem by the seating spring so that the stem S cannot be overly elongated and damaged, and so that the tappet can be set readily in proper relation to the shank.

This means preferably comprises a tension resisting means connected at its ends to the head and shank, respectively, soV as to provide a lost motion connection between the head and shank.

In one form, the tension means may comprise a .i

wire or rod I8 of small diameter and high tensile strength connected to the head and to the shank.

For providing a convenient connection between the wire and shank, the shank I is composed of an upper portion I4 and a lower portion I5, the t' The head il has a portion I'I by whichit is conl i nected xedly to the upper end of the stem 9, the portions I4 and II being telescopically received in, and in screw threaded engagement with, the stem 9. Both the shank portion I4 and head portion I'I, in addition to being in threaded engagement with the stem 9 as described in my above copending application,` may be spot welded or brazed to the stem 9.

The upper portion I4 of the shank is provided with an axial bore I9. which extends axially entirely through the upper portion I4 and is open at both ends. The rod'IS extends through the borel I9 and fits therein with slight radial clearance so as to be relatively movable endwise thereof. The lower end of the rod I8 extends beyond the lower end of the upper portion I4 of the shank.

The lower portion I of the shank is provided with an axial bore which opens through the upper end of the portion I5 and extends part way toward the lower end. The lower end or" the rod I8 is snugly accommodated in the bore 2t and is secured in iixed adjusted position therein, as will be more fully described hereinater.

The upper end of the rod lil is provided with a ball 2l and the lower end oi the portion l? is provided with a trough 22 and with a transverse bore 23 spaced from the lower end of the por tion I'I and intersecting the upper end oi the trough, as best illustrated in Figure 5. Thus, while held with its axis parallel to the axis of the portion Il, the upper end of the wire or rod i8 may be moved radially while it is aligned with the trough 22 and the ball is aligned with the bore 23 so as to dispose the wire in the trough and the ball in the bore 23. The bore 23 is of suicient diameter relative to the ball so that the ball can rise from a seated position against the lower wall portion of the bore to a raised position thereabove. Thus, the wire or rod I3 is connected to the portion I1 for limited axial movement.

The lower end of the wire or rod IB is secured in xed position relative to the lower1 shank portion I5, preferably by means oi set screw 2t.

When the valve is in a normal condition in which it is unstressed by the seating spring, the various parts are related as illustrated in Figure 1i.

In this relation of the parts, there is a slight clearance X between the lower end of the upper shank portion It and upper end of the lower shank portion I5, the ball 2l is at its lower limit of movement and resting on the lower wall of the bore 23, and the set screw 2li holds the lower end of the rod I8 in iixed position relative to the shank portion I5.

The valve in this normal condition is installed by inserting its stem in the guide 4 and seating the head t. The seating spring I3 is then connected and by its force elongates the stern a distance equal to the clearance X after which the spring I3 cannot elongate the stem 5* further due to the rod or wire I8.

In this condition, with the tappet at its lowermost position, the adjustable head of the tappet 7 is adjusted to a position in which it is barely in contact with the lower end of the lower portion I5, or if desired, a few thousandths higher so as to reduce the elongation of the stem slightly.

This leaves the stem 9 slightly elongated with the lower portion I5 of the shank riding on the tappet head I in all seated positions of the valve. 'Ihe limited axial movement of the wire or rod It relative to the head 8 allows the stem $3 to elongate to the allowable limit and to return without interference toward normal unelongated condition so that the head is lifted by the stem s and not by the rod.

Thus a lost motion connection is provided between the head and shank of thervalve as a result of which they can be moved axially relative to each other within fixed limits so that the elongation of the stem is permitted within proper' limits, and undue elongation is eliminated, and proper setting of the valve is simplied.

In operation of the engine, therefore, the shank rides on the tappet in all operating positions.

As the tappet rises from its lower position,.the stem 9 is progressively relieved from the force of the seating spring I3, the elongation of the stem 9 is progressively reduced by the self-restoring characteristics of the stem, and the ball 2| is progressively lifted, until the convolutions of the stem reach their normal unstressed condition or close against each other.

.As soon as the elongation is fully eliminated,

lifting of the valve head by the stem 9 begins and thereafter, continues as in the case of a conventional valve.

Upon the return stroke, the valve head 8 is seated by virtue of the pull exerted on the shank portion I4 by the spring I3. The initiation of the elongation of the stem 9 is delayed until the head seats, due to the fact that the shank portion l5 is riding on the tappet. Immediately thereupon, the stem. 9 begins to elongate and continues to do so as long as the tappet, if properly set, lowers.

This action of the stem cushions the impacts arising from engagement of the valve head on the seat on the closing stroke of the valve` Since clearance between the tappet and valve is eliminated by resilient elongation of the stem 9, there is no impact of the tappet against the valve on the opening stroke but only a gradual return of the convolutions of the stem 9 to unstressed position, any impact being distributed as small increments over a large number of convolutions and cushioned by oil films between the convolutions.

When the valve is in seated position and the clearance X shown in Figure 4 is totally removed, the ball 2| is seated at the lower limit of the bore 23. As the tappet lifts the lower portion I5 of the shank, the ball is lifted from its seat as the convolutions of the spring portion 9 close, the ball being permitted a sufficient distance of travel upwardly axially of the stem of the valve so that it does not quite reach its upper limit of movement in the portion I'I prior to the complete closure of the convolutions of the spring portion 9. The valve is usually set at the factory with the clearance at X for the particular engine being substantially equal to the clearance that normally would be allowed for a conventional valve.

After the valve is installed in an engine, it does not matter whether the screw 24 remains'in iirm engagement with the rod I8 or not as the downward elongation of the spring stem 9 by spring I3 is limited by thetappet itself and the upper movement of the lower shank portion I5 relative to the head 8 is limited by engagement of the convolutions of the stem 9.

I'he stem 9 preferably is high carbon spring steel of Rockwell hardness of 43 to 45. It is installed in the guide with ya drag fit. The Flift in average sizes is about 15e inch.

Referring next to Figure 6, the valve there illustrated is similar to the valve illustrated in Figure 1 except that the means providing the lost motion connection between the head and shank for limiting the elongation of the Astem is somewhat modified. i

As there illustrated, the valve has a head 25 with a portion 26 secured to a spring stern 2l. A one piece shank 28 is provided instead of the two piece shank I Il heretofore described. The shank 28 is connected to the stem 9. The lost motion connection is provided by `a wire or rod 29 connected to the head in the same manner as the rod I8 hereinbefore described by means of a ball end 30 and lower wall of a bore 3l so as to have limited movement axially of the valve stem. The lower end of the rod 29 is xedly secured to the shank 28 by the set screw 32. If desired, the wire may be xedly secured to the head portion 26 and the m'ovable connection may be provided between the rod and shank.

The lower end of the rod 29 is secured in fixed position to the shank 28 while the stem 21 is unstressed and while the ball 3U of the rod 29 is spaced above the lower wall of the bore 3| a distance equal to the maximum elongation to be permitted the stem 9.

In Figure 7, another modification is illustrated. In this form the lost motion connection is by means of a wire or rod 33 iixedly connected at its upper end to the `head 34 and at its lower end to a shank 35. i The wire is bowed and preferably reversely bowed and sinucus between its ends and can be drawn straight, or more nearly straight, by movement of the shank 35 away from the head 34. The curvature of the wire is such that when it is drawn straight, or to a more nearly straight condition in `which its resistance to further straightening becomes unduly large relative to the straightening force applied by the seating spring, the increase in its overall length or the straight-line distance between its ends is equal to the maximum elongation to .be allowed in the stem. Since the rod serves only a temporary purpose, it does not mattei' if it subsequently crystallizes and breaks.

' In the form illustrated in Figure 8, the valve has a head portion 36 and a shank 3l with an intermediate stem portion 38 in a form of a coil spring heretofore described. The lost motion connection between the head and shank is provided by means of a wire or tension rod 39 connected to the head portion and a cooperating wire or rod 4i! connected to the shank. The rod 39 has a terminal loop 4I and the rod 49 has a terminal loop 42, these terminal loops passing through each other and being adapted to engage and prevent further movement of the shank 3l away from the headV when the spring stem` 3B is elongated the maximum preselected amount.

In the description and in some of the claims, the valve is described for convenience in description as though operating in an upright position but it is to be understood that the positional terms referenced to an upright position are relative for convenience in reciting the relative position of the parts to each other and are not to be considered as limiting the position of the parts relative to a vertical or horizontal absolute.

Having thus described my invention, I claim:

l. A poppet valve comprising a head, a head supporting and guiding stem coaxial with, and xedly connected at one end to, the head, said stem having a shank portion at its opposite end 'adapted for connection to a seating spring and for operative connection to a valve operating tappet, said stem having a portion intermediate the head and shank portion in the form of an elastically elongatable coil spring which is coaxial with the head and is adapted to fit Within a tubular valve guide and support and guide the valve head for axial reciprocation, said intermediate portion in normal condition being unstressed and being elongatable by movement of -the shank away from the head endwise of the stern, and tension resisting means within the stem and connected at one end to the head and at the other end to the shank so as to arrest said movement of the shank away from the head at ya predetermined extended position relative to the head and so as to be unopposed to the return of the shank toward the head.

2. A valve according 'to claim l characterized in that said tension resistance means includes means connecting the head and shank with a lost motion connection.

3. A valve according to claim 2 characterized in that said tension means is a tension member connected at its opposite ends to the head and to said shank portion, respectively, and one of 7 said end connections is a lost motion connection.

4. A valve according to claim 1 characterized in that said tension means is an elongated member having portions angularly disposed to the axis of the stem and to each other and adapted to be moved toward parallelism with the axis when subjected to an endwise pull.

5. A valve according to claim 4 in that said tension member is a member which for at least a portion of its length is bowed transversely oi the stem.

6. A. poppet valve comprising a readily elastically elongatable head supporting and guiding stem, a head iixedly connected t0 one end of the stem, a shank coaxial with the stem and having an upper portion nxedly connected to the other end of the stem and adapted for connection to a seating spring for thereby exerting an endwise pull on the stem, said shank having a lower portion movable axially in relation to the upper portion and adapted for engagement by a tappet for lifting the valve, a tension member connected at one end to the head for movement axially of the stem relative to the head, cooperable means on the head and member for arresting said movement of the member in a direction away from the head at a predetermined position, said shank having a lower portion xedly connected to said member and movable therewith axially relative to the stem and relative to the upper portion of the shank and constrained by said member to a predetermined maximum position from the head, said lower portion having a shoulder :facing toward and spaced a predetermined distance from a complementary shoulder on the upper shank portion when the stem is in non-elongated condition, and said shoulder being positioned so to engage and limit the movement of the upper Shank portion in a direction away from the head and constrain the upper shank portion to a position of maximum spacing from the head such that the stem must be axially elongated a predetermined amount when the shoulders are in contact with each other.

7. A poppet valve comprising a readily elastically elongatable head, supporting and guiding stem, a head connected to one end of the stem, a shank having an upper portion connected at the other end of the stem and having a lower portion coaxial with the upper portion and movable endwise upwardly into contact with the lower end of the upper portion and downwardly away from contact therewith, a tension rod connected at its upper end to the head for limited movement axially of the head, said upper portion of the shank having an axial bore and accommodatinr said rod for movement axially relative thereto, said rod extending through and beyond the lower end of said upper portion, said lower shank portion being connected xedly to the rod and having an upper end facing toward the lower end of the upper shank portion, the connection oi one end of said rod being lost motion connection whereby the lower shank portion may move a limited amount in a direction away from the head to a fully extended position and said upper end of the lower portion and lower end of the upper portion of the shank being spaced apart with slight clearance when the stem of the valve is in unstressed condition.

8. A poppet valve comprising a stem in the form of a coil spring, a head member xedly connected to one end of the stem, a shank member having an upper portion connected to the other end of the spring in coaxial relation therewith, a tension rod connected at one end 'to one of the members for movement axially of the spring relative to said one of the members a limited amount, and connected at the other end to the other of said members, said uppershank portion having an axial bore and open at both ends and said rod extending through said bore and beyond the lower end of the upper shank portion, a lower shank portion connected to said rod and coaxial with the upper sha-nk portion and having at its upper end a shoulder spaced slightly from the lower end of the upper shank portion when the spring is in unstressed condition and the lower shank portion in its maximum extended position.

No references cited.

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