US2240299A

US2240299A - Valve actuating mechanism

Info

Publication number: US2240299A
Application number: US231496A
Authority: US
Inventors: Holmes Dan Campbell; Griffiths Alan Henry
Original assignee: SELF ADJUSTING TAPPETS Ltd
Current assignee: SELF ADJUSTING TAPPETS Ltd; SELF-ADJUSTING TAPPETS Ltd
Priority date: 1938-09-24
Filing date: 1938-09-24
Publication date: 1941-04-29
Anticipated expiration: 1958-04-29

Description

April 29, 1941 D. c. HoLMEs ETAL 3 3 VALVE ACTUATING MECHANISM Filed Sept. 24, 1958 TORs Was;

Alan Henr @Wfiks ATTORNEY.

F417 can b225 2 Patented Apr. 29, 1941 UITED STTS Tar OFFICE VALVE ACTUATENG MECHANISM Application September 24, 1938, Serial No. 231,496 I 7.

15 Claims.

This invention relates to valve actuating mechanism, particularly to self-adjusting valve tappets.

Further, the invention relates to valve tappets of the general type shown and described in the patent to Clutterbuck No. 1,962,057, dated June 5, 1934, and the patent to Holmes No. 2,066,976, dated January 5, 1937.

One of the objects of the present invention is to provide a more simple self-adjusting valve tappet and one that may be more cheaply constructed, and one that will be more certain in its action, and yet embody the spring operated self-adjusting action of'the patents referred to and the deformable abutment head of the said Holmes .patent.

Another object of the invention is to provide, in a self-adjusting valve tappet of the type referred to', a contact piece of simple form which will have a, minimum of retarding action on the relatively movable members of the tappet so that the tappet may be used in connection with the engines in which the tappets are rotated in the operation thereof without adversely afiecting the self-adjusting operation of the tappet.

Another object of the invention is to provide a self-adjusting valve tappet of the mechanical type with means for frictionally retaining the relatively movable members in retractive position so that the tappet may be conveniently installed in place. The object is also to provide a limiting device for the reverse action of the members so that the spring will not unduly uncoil when the parts are released.

Other objects of the invention will appear from the following description taken in connection with the drawing, which forms a part of this specification, and in which:

Figure 1 is a sectional view of a portion of an engine illustrating the adaptation of the tappet of this invention thereto;

Figure 2 is an enlarged sectional view of a self-adjusting valve tappet made in accordance with this invention;

Figure 3 is a cross-sectional View on the line 3-3 of Figure 2; and

Figure 4 is a perspective view of one of the tappets.

Referring particularly to Figure 1, an internal combustion engine Hi is shown having a cylinder H, a piston ii, a poppet valve I3, and a spring M which yieldably retains the valve |3 in closed position on its seat. A cam shaft i5 operated from the engine crank shaft has a cam l5 which operates a tappet ll slidably mounted in a boss I8 formed in the engine casting. The part marked I! in Figure 1 is the base or supporting portion of the tappet and the self-adjusting mechanism of the tappet is indicated generally at l9. This tappet I9 operates between the cam shaft I5 and the stem of the valve Is to move the valve from its seat against the action of the spring M and such'spring returns the valve to its seat and causes the tappet to follow the cam onthe shaft.

With the usual construction there is a threaded adjuster on the valve tappet so that the tappet may be adjusted to the required length to provide slight clearance between the tappet and the end of the valve stem when the valve is closed, thus insuring seating of the valve and providing for some expansion when the parts become heated. When the parts are cold this clearance causes a noisy operation of the valve mechanism and it is the object of self-adjusting valve tappets of the type here referred to to contract or elongate the tap-pet to provide for changing conditions caused by expansion and contraction of the parts and by wear.

The present invention provides both a spring take-up mechanism and. a deformable abutment and it is this construction one form of which is specifically illustrated in Figures 2, 3, and 4.

The supporting part of the tappet is indicated at as in Figure 1. This is preferably cylindrical in shape and is guided in the boss provided in the engine. The self-adjusting means is mounted on the supporting part I1 and is indicated generally at H]. It has a shank 20 which extends into the supporting part I? and there is a disk 2| surrounding the shank and lying between a shoulder 22 thereon and the upper face 23 of the part These parts ll, 20, and 2| may bemade of separate pieces and are so shown, but under some circumstances it may be desirable to make all three of them in one piece. The part 2| extends beyond the periphery of the face 23 .and forms a flange in which there are two opposed notches 24 for a purpose hereinafter described.

The upper end of the shank 20 is formed with a head 25 which is exteriorly threaded as at 26, and the whole piece is bored out from end to end as shown at 21. This piece comprising the shank 20 and its threaded head 25 is one of the members of the self-adjusting portion of the tappet.

The other self-adjusting portion of the tappet is the member 28 which is shown in the form of a sleeve surrounding and threaded to the head 25 as by the threads 29, and thus the two members are adjustable one relative to the other to lengthen or shorten the tappet.

Spring means for moving the adjusting members relatively is provided in the form of a coil spring mounted in the bore 21 of the shank member, a shaft 3| extending through the coil spring 30 and a pin 32 at the upper end of the shaft. The upper end of the coil spring 30 has its end 33 bent over into a slot or opening 34 in the member 25, and the lower end of the spring is bent into a slot 35 in the lower end of the shaft 3|. The pin 32 extends crosswise through a slot 36 in the upper end of the shaft 3| and into openings 31 in the sleeve 28. The pin 32 is assembled in place as shown after the spring 30 has been wound up sufiiciently by rotating the shaft 3|. Then the pin 32 is retained in place by a split ring 38 surrounding thesleeve 28 in a groove 39 formed in the outer wall thereof. The spring 30 is so coiled that its tendency in unwinding is to turn the sleeve member 28 relative to the member 25 in a direction to elongate the tappet.

The upper part of the sleeve member 28 is internally of cylindrical form as at 40 and mounted to slide freely therein is a disk 4| having a central boss 42. The disk 4| is centrally bored as at 43 and both its upper and lower surfaces 44 and 45 are of somewhat conical shape. Between the lower surface 45 of the disk 4| and a shoul der 48 formed on the sleeve member 28 are several spring disks 4?. These disks are provided with central openings surrounding the boss 42 and they are guided thereby and by the interior cylindrical surface 45 of the sleeve member 28.

Mounted above the disk 4! is a contact piece 50 which is preferably flat except for a central portion which is pressed inwardly to form a boss 5| extending into the opening 43 of the disk 4|, thus centrally positioning the contact piece on the disk. This construction also produces substantially a line contact between the disk and the contact piece, as at.52, the contact piece touching the disk only at the corner. at the upper end of the opening 43. Thus there is little friction between these two parts and the disk 4| is therefore not greatly retarded in its rotary movement with the sleeve member 28.

The contact piece 50 has two downwardly extending arms 53, one on either side, and these arms extend downwardly close to but out of contact with the sleeve 28 and into the slots 24 referred to above. At their lower ends the arms are of T-shape having branches 54 which extend under the flange 2| and thereby limit the upward movement of thecontact piece. The arms 53 are of such length and the lugs 54 are so positioned, that the sleeve member 28 may be moved by the spring 30 just enough to provide for the maximum amount of adjustment required for a particular valve mechanism. In other words these arms form a stop or limiting means for the elongating action of the tappet and of course they also insure that there will be no turning action between the contact piece 59 and the shank member 25 of the self-adjusting mechanism.

For the purpose of facilitating installation of the tappet in the-engine the adjusting members are so formed that the member 23 may by hand he threaded down on the member 25 until the lower of the member 28 contacts with the disk 2| and the friction between these parts will then retain the member 28 in that position, as shown in dotted lines in Figure 2, against the action of the spring 38. The tappet may then be placed in position in the engine and the member 28 is turned slightly to free it from its friction contact and the spring 30 will then continue to turn the member 28 .to take up the clearance between the tappet and the valve stem. Thereafter the threaded engagement of the members 25 and 28 will cause a retraction of the tappet against the action of the spring 30 in case of elongation of the valve stem by reason of heat, and as the parts cool off or as there is wear in the parts, the spring 30 will cause the members 25 and 28 to take up the clearance. Also, the spring disks 41 will insure complete closing of the engine valve during the period of adjustment which is sometimes gradual. The arrangement of the contact piece in connection with the parts that must revolve with the sleeve member 29 is such that it does not retard that movement, and if the tappet is intended to be rotated by the cam action as it is in some engines this movement of the contact piece 50 with the tappet piece I7 will not affect the operation of the selfadjusting mechanism.

The parts of this tappet are readily assembled and disassembled by reason of the spring arms 53 holding them in place. These arms 53 are preferably of spring metal and when the sleeve 23 is threaded down against the disk 2| the arms 53 may be sprung out of the slot 24 and the contact piece removed. This releases the disk 4| and the spring disks 41. The split ring 38 may then be removed and the pin 32 pushed out of one side from the other. This releases the shaft 3| and the spring 30. Or if desired, the sleeve 28 may be removed with the pin 32 and shaft 3| 7 in place, the end 33 of the spring 30 being withdrawn from its position in the hole 34.

The parts may be as easily replaced by reversing the operation, except that the spring 30 will of course have to be put under tension after its end 33 is in place, as previously described.

While we have herein described in some detail a specific embodiment of our invention, which we deem to be new and advantageous and may specifically claim, we do not desire it to be understood that our invention is limited to the exact details of the construction, as it will be apparent that changes may be made therein without departing from the spirit or scope of our invention.

What is claimed is:

1. A self-adjusting valve tappet comprising two members threaded together, a spring tending to turn the members relatively to elongate the tappet, the threaded engagement of said members being such that under certain pressure conditions in the operation of the tappet the members will move relatively to retract the tappet against the action of said spring, a contact piece extending over one of said members and arranged to contact the valve stem or push rod and having a part keyed to the other member, said piece having a small amount of contact surface between itself and the adjacent member relative to the amount of surface in contact with the valve stem or push rod, so that said piece and adjacent member may move relatively with little friction, in the adjusting operation of the tappet.

2. A self-adjusting valve tappet comprising two members threaded together, a spring tending to turn the members relatively to elongate the tappet, the threaded engagement of said members being such that under certain pressure conditions in the operation of the tappet the members will move relatively to retract the tappet against the action of said spring, a contact piece between one of said members and the engine valve and keyed to the other of said members, said piece having a much larger contact surface against the valve than against the member, whereby the member may readily move relatively to said piece during the adjusting operation of the tappet.

3. A self-adjusting valve tappet comprising a supporting member having a threaded part, an adjusting member having a sleeve part threaded to said supporting member and an abutment part slidable in the sleeve part, a spring disk compressible between the parts of said adjusting member, and a contact piece keyed to the supporting member and having a part resting against said abutment part of the adjusting member.

4. A self-adjusting valve tappet comprising a supporting member, an adjusting member threaded to the supporting member, a spring tending to move the adjusting member relative to the supporting member, and a contact piece keyed to the supporting member and having small surface contact with the adjusting member near the axis of the tappet.

5. A self-adjusting valve tappet comprising a supporting member, an adjusting member threaded to the supporting member, a spring tending to move the adjusting member relative to the supporting member, and a contact piece having a portion between the adjusting member and the engine valve and having an arm extending to and keyed with the supporting member.

6. A self-adjusting valve tappet comprising a supporting member, an adjusting member threaded to the supporting member, a spring tending to move the adjusting member relative to the supportingmember, and a contact piece having substantially circular line contact with the adjusting member.

7. A self-adjusting valve tappet comprising two members threaded together, a spring tending to turn the members relatively to elongate the tappet, said members having cooperating surfaces adapted to abut when the members are relatively moved to the extreme position in opposition to the action of said spring and to frictionally retain the members in such position, and means to limit within the free action of the spring the reverse relative movement of said members.

8. A self-adjusting valve tappet comprising two members threaded together, a spring tending to turn the members relatively to elongate the tappet, said members having cooperating surfaces adapted to abut when the members are relatively moved to one extreme position in opposition to the action of said spring and to frictionally retain the members in such position, and means comprising a piece keyed to one of said members and extending over the end of the other of said members and forming a limit or stop for the reverse relative movement of said members.

9. A self-adjusting tappet comprising two members threaded together, one of said members having a sliding abutment part, a spring disk compressible by said abutment part, and a contact piece having a part resting against the abutment part of one of said adjusting members and keyed to the other of said members.

10. A self-adjusting tappet comprising two members threaded together, and a contact piece having a part'resting against and free to turn relative to one of said adjusting members and keyed to the other of said members.

11. A self-adjusting valve tappet comprising a supporting member, an adjusting member having a sleeve part threaded to said supporting member and an abutment part slidable in the sleeve part, said abutment part having an upper conical surface and a central opening, a spring disk compressible between the parts of said adjusting member, and a contact piece having a generally plane surface with a central boss positioned on said abutment part with the boss in said central opening, the contact piece thereby forming a line contact with the abutment part.

12. A self-adjusting tappet comprising a supporting member, an adjusting member having a sleeve part threaded to said supporting member and having its upper end formed with a central opening and with a somewhat conical surface around said opening, and a contact piece having a plane surface and a central boss, the boss of said contact piece extending into said opening and thereby forming a substantially line contact with the end of the adjusting member.

13. A self-adjusting tappet comprising a supporting member, an adjusting member having a sleeve part threaded to said supporting member and having its upper end formed with a some-v what conical surface, and a contact piece having a substantially plane underneath surface resting against only the higher portion of said conical surface.

14. A self-adjusting tappet comprising two members threaded together, a spring for relatively moving said members, one of said members having a sliding abutment part, a spring compressible by said abutment part, and a contact piece extending over said abutment and having side arms extending to the other of said members and into slots therein to key the contact piece to rotate with said other member and to retain the parts in assembled position.

15. A self-adjusting valve tappet comprising a supporting member, an adjusting member threaded to the supporting member, a spring tending to move the adjusting member relative to the supporting member, and a contact piece resting against the adjusting member and having circular line contact of small diameter therewith.

DAN CAMPBELL HOLMES. ALAN HENRY GRIFFITHS.