US2322514A - Valve actuating mechanism - Google Patents

Description

June 22, 1943. w. M. Goonwm 2,322,514

' VALVE OPERATING MECHANISM Filed Jan. 12, 1942 AT T IJRNEY INVE N T u R WIL IAM MGuuqgvm Patented June 22, 1943 UNETED STATES PATENT OFFIQE VALVE ACTUATING MECHANISM William M. Goodwin, Central Square, N..Y. Application January 12, 1942, Serial No. 126,5584

12 Ciaims.

This invention relates to a valve actuating mechanism for internal combustion engines wherein a valve of the poppet type is actuated by a valve lifter or tappet functioning in conjunction with a valve spring.

It is well known that poppet type valves of internal combustion engines have the mechanism for lifting or opening them usually arranged so that a slight clearance operating relation is always maintained between certain of the parts interposed between the operating cam and the valve seat. This clearance is so that the valve may always properly engage its seat when in the closed position irrespective of variations in the lengths of the parts produced by expansion and contraction as the result of heat changes. This, of course, results in a valve actuating mechanism which is noisy and lacking in efliciency.

There have been numerous valve operating mechanisms or tappets invented which were de signed to be self-adjusting to automatically maintain all members of the valve lifting or opening mechanism in cooperative contact with each other under all operating conditions. In some of these valve opening mechanisms or tappets there has been utilized mechanical means only, while in others there has been employed hydraulic means for producing automatic adjustments of certain parts with respect to other parts of the mechanism in order to maintain no clearance between any of the parts and at the same time permit the valve to close properly. All of these mechanisms have been relatively expensive to manufacture and many, particularly those employing mechanical compensating units, have I not, in so far as the applicant is aware, been practical or successful. One of the reasons for this seems to be the fact that a sufficiently line or minute adjustment of the relatively movable members of the compensating units has not heretofore been obtained for compensating for the mic'rometric variations in lengths of the parts produced by expansion and contraction thereof as the result of wear and changes in temperature.

The primary object of this invention is to produce an improved self-adjusting or compensating valve operating mechanism which will automatically and accurately function to compensate for changes in lengths in the valve stem and associated parts occasioned by temperature variations as well as by wear of said parts and thus provide for maximum efficiency and performance by eliminating noise and vibration, improving valve timing and reducing wear. A more specific object of the invention resides all in providing a self-adjusting valve operating mechanism which is inexpensive, simple and durable in construction and which is dependable, accurate and silent in operation.

Specifically the invention contemplates the provision of a valve operating mechanism which utilizes simple and inexpensive mechanical means only, that is, one which functions without the aid of liquid such as oil as a medium to produce minute adjustments for automatically introducing or taking up slack in such mechanism.

Other objects and advantages pertaining to the specific construction of my novel valve actuating mechanism and to the form and relation of the parts thereof will more fully appear from the following description taken in conjunction with the accompanying drawing in which:

Figure l is a detail vertical sectional view of an engine head having a spring loaded poppet valve operatively associated therewith and a self-adjusting or compensating valve actuating mechanism embodying the various features of invention operatively connected with the valve for lifting or opening said valve.

Figure 2 is a detail horizontal sectional View taken on line 22, Figure 1.

Figure 3 is a detail vertical sectional view taken on line 3-3, Figure 1.

Figure 4 is a view similar to Figure 3 and illustrates a modified form of the cam and cam follower members shown in Figure 1 for introducing slack in the valve actuating mechanism.

Figure 5 is a detail side elevation of adjacent portions of a cam shaft, a cam and a cam follower for actuating a valve tappet showing the offset relation of the cam and cam follower with respect to each other.

Figure 6 is a detail vertical sectional view of a rocker arm showing a modified form of slack take-up or compensating unit associated therewith.

Figure 7 is a detail vertical sectional view taken on line 'l1, Figur 6.

In order to illustrate my novel valve actuating mechanism, I have indicated in Figure 1 a portion of a cylinder head Ill having the usual exhaust or intake port defined by a valve seat H. A poppet type valve I2 is shown operatively connected with the head to move into and out of engagement with the seat II for opening and closing the port. Valve 12 is provided with a stem l3 slidably mounted in a guide It provided-in head it] and a valve spring I5 is shown to the closed position on its seat in the usual manner. 7

The valve lifting or opening mechanism of this invention comprises the usual cam shaft indicated at H. The character |8 indicates a cam carried by the shaft H, the lobe l8 of which is adapted to cooperate with spring l for actuating the valve lifter or tappet, indicated generally by the numeral IQ, of this invention for opening and closing Valve l2. The cam |8 is of conventional construction and may, as shown in Figure 5, be mounted in offset relation with respect to the axis of a cam follower 2| forming a portion of my automatic tappet. The cam follower 2| is shown in the form of a sleeve which may be supported for vertical reciprocative movement in a suitable tappet guide (not shown) in the usual manner, said guide being connected with the base of the engine. The bottom of the sleeve is closed as at 22 and forms a surface adapted to rest upon cam l8. As shown in'Figure 5, the offsetting of cam l3 relatively to the sleeve 2| is such that the periphery of the cam has a much longer line contact with the sleeve bottom at one side of the sleeve axis than at the opposite side of said axis so that the cam, during rotation thereof, constantly tends to rotate the sleeve in the direction indicated by the arrow on said sleeve in Figure 5 by reason of the preponderance of frictional contact between the sleeve and cam at one side of the sleeve axis. The inner face of the bottom 22 is provided with an arcuate bearing or seat 23 which supports the lower curved end 24 of a vertically disposed push rod 25.

The upper end of the push rod 25 carries a head 21 which is preferably so connected with said push rod that rotary movement of the push rodwill produce a corresponding rotary movement of the head 21. The upper end of the head 2! is formed with an arcuate socket or seat 29 in which rests the spherical end 30 of an adjusting screw 3| which extends upwardly from the head 2'! through a suitable threaded opening 32 provided in one end of a rocker arm 33. It will now be apparent that the end 24 and socket or seat 23 provide coupling means for frictionally transmitting rotary motion from the cam follower 2| to the push rod 25. In a similar manner the end 30 and seat or socket 29 provide coupling means for frictionally transmitting rotary motion from the head 21 to the screw 3|.

The rocker arm 33 is rotatably mounted on a horizontally disposed shaft 35 which extends longitudinally of the motor in the usual manner. Shaft 35 is shown supported by suitable brackets indicated at 36 connected with the head It). The inner end of the rocker arm 33 contacts with the upper end of the valve stem |3 for opening said valve against the action of the spring|5 in the usual manner. The adjusting screw 3| extends a short distance above the adjacent end of the rocker arm 33 and has a relatively weak torsional spring 38 mounted thereon, said spring being connected with the screw and with the rocker arm for producing a rotary movement of the screw in a direction to move the adjacent end of the rocker arm away from the head 21. As shown in Figures 1, 2 and 3 the rocker arm 33 is provided with a pendant cam 40 which is arranged intermediate the rocker shaft 35 and the adjusting member 3|. .The head 21 is provided with an arm 4| which extends laterally from one side thereof to provide a cam follower adapted to engage the cam 40. A torsional spring 42 may, as shown in Figures 1 and 2, be mounted at the upper end of the head 21. This spring has one end connected with the rocker arm 33 and the other end connected with the head 2'! or cam follower 4| for urging the cam follower toward the cam 40.

As heretofore explained, cam l8 tends to rotate sleeve 2| so long as any substantial pressure exists between these members. As the push rod 25 is being raised and lowered by cam l8, the rotary action of cam l8 upon said rod constantly urges the cam follower 4| to move toward cam 40 into engagement therewith. During the up ward and downward swinging movement of the end of the rocker arm adjacent the head 27, cam follower 4| is moved longitudinally with respect to the cam 40. In other words, as the head 2! and the adjacent end of the rocker arm 33 move upwardly, the cam 40, being closer to the axis of rocking movement of the rocker arm 33 than the head 21, will have a shorter arc of movement than said head. The cam follower 4| will, therefore, move longitudinally of cam 40 and be caused to swing outwardly or in a clockwise direction, as viewed in Figure 2, due to the face of said cam engaged by the cam follower being inclined upwardly and toward the vertical plane passing through the rocker arm longitudinally thereof at the junction of said cam face with the rocker arm 33. As the push rod 25 and the adjacent end of the rocker arm 33 move downwardly, the cam follower 4|, being urged toward the cam 40 by the coaction of the cam I8 and the torsional spring 42, is maintained in contact with the cam 40. The outward swinging movement of the cam follower 4| produced by the cam 40 will, of course, be against the rotary action produced by cam |8 upon the cam follower 2|, and which is frictionally transmitted through the seat 23 and end 24 of the rod 25 to said rod and to head 21. The outward swinging movement of the cam follower 4| produced by the cam 40 will, likewise, be against the action of the spring 42. When the push rod 25 and the adjacent end of the rocker arm 33 move downwardly, spring 42 coacts with the rotary action of the rod 25 produced by cam l8 to maintain the cam follower 4| in engagement with the cam 40. It will be obvious, however, that spring 42 may be dispensed with, in which case the cam follower 4| is urged toward the cam 40 to be maintained in continuous contact therewith by the rotary action of cam |8 upon the rod 25 only. Furthermore, cam |8 may be arranged substantially centrally with respect to the sleeve 2|, in which case the spring 42 may be used alone to yieldingly urge the cam follower 4| toward the cam 40.

This forward and backward swinging movement of the cam follower 4| produced by the cam 40 coacting with cam l8 and/or spring 42 produces a corresponding rotary movement of the head 21 which, in turn, is frictionally transmitted through the seat 29 and end 30 t0 the adjusting screw 3| and tends to produce a corresponding rotation of the screw first in one direction and then in the opposite direction. The outward swinging movement of the cam follower 4| tends to rotate the adjusting screw 3| in a direction to move the end of the rocker arm 33 adjacent said screw outwardly away from the head 21 and take up slack in the valve actuating mechanism. When the cam follower 4| moves in the opposite direction, or inwardly, toward the cam 40, the head 21 will tend to rotate the adjusted member 3| in the opposite direction and cause be obvious that if the friction between the threads provided on the screw 3| and on the rocker arm 33 is greater than the friction produced between seat 29 and end 3!], the adjusting screw 3| will not be rotated during the swinging movement of the cam follower 4| with the result that there will be no relative movement between the adjusting member and the rocker arm. The adjusting screw 3| is usually maintained against rotary movement during the opening of the valve |2 due to the load placed on the rocker arm 33 by valve spring l5 and to the fact that rotation of the screw 3| caused by the outward swinging movement of the cam follower 4| effects movement of the rocker arm away from the head 21 and has the effect of elongating the valve operating mechanism. It follows, therefore, that under normal operation, cam 45 and cam follower 4| do not effect adjustment of the valve operating mechanism on the upward or Opening stroke thereof. On the other hand, during the downward movement of the push rod 25 and head 21, the action of cam 40 and the cam follower 4| is assisted by the inclined cam surface provided by the screw threads on screw 3| and tend to rotate said screw in a direction to produce downward movement of the end of the rocker arm 33 adjacent thereto toward the head 21 and introduce slack in the valve actuating mechanism as valve I2 is being closed. If the slack thus introduced in the valve actuating mechanism is sufficient to cause an operating clearance between parts of the mechanism, such as between the rocker arm 33 and valve stem l3, spring 38 functions to rotate screw 3| sufficiently to take up this clearance and maintain a noclearance operating relation between the parts of the mechanism.

The rocking movement of the cam follower 4| is relatively slight during each cycle of movement of the push rod 25 and therefore any rotation of the adjusting screw 3| produced by this rocking movement of the cam follower will likewise be very slight and the movement of the rocker arm relative to the adjusting screw produced by the slight rotary movement of the adjusting screw will be very minute for each cycle of operation of the valve actuating mechanism. It, therefore, requires many cycles of operation of my valve actuating mechanism to produce an appreciable movement of the end of the rocker arm adjacent head 2'! relative to said head and thus effect automatic adjustment of the mechanism. This slight adjusting action of the screw 3| produced by cam 40 takes place only during the upward or downward movement of the push rod 25 and head 21. Therefore, any rebound of Valve I2 as the same engages its seat I I will have no appreciable effect upon cam 40 to cause said cam to actuate adjusting screw 3 I.

In the structure shown in Figure 4 the cam follower 4| is provided with a slot or recess which receives the cam 45 therein. The cam follower 4| and the cam 40' function in substantially the same manner as the cam) and the cam follower 4| shown in Figure 1 with the exception that instead of the cam follower being yieldingly urged toward the cam. said cam follower is positively moved in first one direction and then in the opposite direction by the cam during the upward and downward movement of the push rod 25 and the adjacent end of the rocker arm 33.

This 75 positive rocking movement of the cam follower 4| tends to first take up slack in the valve actuating mechanism and then to introduce slack in said mechanism as is the case with the cam and cam follower shown in Figure 1.

It will now be understood that when the cam follower 4| is moved inwardly during the upward movement of the push rod 25 by the cam little or no rotation of the adjusting screw 3| will take place for the reason explained hereinbefore when describing the structure of Figure 1. On the other hand, when the push rod 25 is moving downwardly, the action of the spring IS on the rocker arm 33 coupled with the inclination or pitch of the screw threads tends to rotate the screw 3| in a direction to introduce slack in the valve actuating mechanism. It will, therefore, be seen that a slight slack is produced in the valve actuating mechanism during each revolution of the operating cam l8 and cycle of operation of the push rod 25. When a clearance occurs in the valve actuating mechanism, the torsional spring 38 functions during the idle portion of the operation of the cam 8 to rotate the adjusting screw 3| in a direction to take up such clearance. In other words, the cam members to and 4| or 40' and 4| function to introduce slack into the system while the function of the spring 38 is to take up slack in the system whether such slack occurs either from contraction of the push rod 25, the valve stem i3 and the members associated therewith or from wear or other causes.

The structure shown in Figures 6 and '7 function similarly to that shown in Figure 1. In Figure 6 I have shown the adjusting screw 3| as being screw threaded in a sleeve which is journaled in a suitable opening 46 provided in the end of the rocker arm, as 33', adjacent the head 21. The sleeve 45 has an outwardly extending lateral flange 4! at the lower end thereof which engages the adjacent portion of the rocker arm for limiting the upward movement of the sleeve with respect to said arm and for providing clutch or friction surfaces at the upper side of the flange and the adjacent lower side of the rocker arm for frictionally maintaining the sleeve against rotation with respect to said arm. A torsional spring 48 is mounted on the upper end of the sleeve 45 and has one end connected with said sleeve and the other end connected with the rocker arm 33' for yieldingly urging the sleeve to rotate in a direction to take up slack in the valve actuating mechanism. In the structure shown in Figures 6 and 7 the adjusting screw 45 is rotated in first one direction and then in the opposite direction during the upward and downward movements of the head 2? by the action of a cam provided by flattening a portion of the upper side of the rocker shaft 35. The cam follower in this instance comprises a block member 5| which is mounted for vertical reciprocative movement in a suitable aperture 52 provided in the rocker arm 33' over the shaft 35'. This cam block 5| is provided with a cam recess 53 extending downwardly from the upper end thereof. Recess 53 has one side thereof substantially flat and parallel with the adjacent outer face of the block 5| as shown in Figure 7, while the opposite side 55 of the recess 53 is tapered upwardly and outwardly a 5 6 is urged into contact with the cam side 55 of the recess 53 by the action of the cam I8 upon the tappet sleeve 2| in the manner described hereinbefore in connection with the structure shown in Figure 1.

When the structure shown in Figures 6 and 7 is in operation, the rocking movement of the rocker arm 33 with respect to the shaft 35 causes the cam follower block to move transversely of the cam surface 50 and thereby move outwardly a slight amount with respect to the rocker arm 33'. This slight outward movement of the cam block 5| produces a corresponding movement of the cam surface 55 with respect to the cam follower arm 55 and thereby cause said arm to swing toward the side 54 of the cam block about the axis of the adjusting screw 3!. This, of course, produces a slight rotary movement of the screw with the result that during the upward movement of the screw produced by the push rod and cam l8, said screw is rotated in a direction to elevate the end of the rocker arm 33 adjacent the head 21 and take up slack in the valve actuating mechanism. When the adjusting screw 3| and the end of the rocker arm 33' adjacent thereto move downwardly with the push rod 25, the rotation of the push rod produced by the offset relation of cam 18 and tappet sleeve 2! causes the arm 56 to move inwardly toward the cam sur face 55 as said surface moves inwardly with respect to the aperture 52. This inward swinging movement of the arm'56 produces a correspending rotation of the adjusting screw 3| in a direction to move the end of the rocker arm 33' adjacent thereto downwardly toward the head 21 and introduce slack in the valve actuating mechanism. It will now be observed that in the structure shown in Figures 6 and '7, like that shown in Figure 1, during the rocking movement of the rocker arm 33' to open the valve I2, the

- adjusting screw 3| is rotated to take up slack in the valve actuating mechanism. The friction between the screw threads of screw 3| and sleeve is greater than the friction between flange 41 and arm 33' so that the sleeve 45 will rotate with the screw 3! and'no adjustment between the rocker arm and head 2'? takes place. On the downward movement of the push rod 25, the arm 56 is maintained in engagement with-the cam face as hereinbefore described. Arm 55 therefore swings inwardly and screw 3i rotates relative to the sleeve 45 tending to introduce slack in the valve actuating mechanism. If slack or operating clearance occurs'in the valve actuating mechanism after the valve H has been closed, spring 48 actuates the sleeve 55 with respect to the screw 3| in a direction to take up the'clearance.

It will thus be understood that my valve actuating mechanism is very simple in construction and operation and has a minutely operating effect during each cycle of operation whereby proper adjustment is automatically obtained and main-- tained throughout continued operation of the valve operating mechanism.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

. 1. A self-adjusting valve actuating mechanism comprising a rocker member, a reciprocative member, means operatively connecting the rocker member and reciprocative member with each other for transmitting motion from one of said members to the other, said means including an adjusting element movable with respect to both of the members and functioning with a cam action to" alter the operative relation between said members, means for intermittently actuating said 75 members, mean rendered effective by the move-- ment of at least one of said members for actuat ing the adjusting element to introduce operative and additional clearance in the mechanism, means for actuating the adjusting element dur: ing the idle period of the rocker member and reciprocative member for taking up clearanc in the valve actuating mechanism.

2. A self-adjusting valve actuating mechanism comprising a rocker member, a reciprocative member, means operatively connecting the rocker member and reciprocative member with each other for transmitting motion from one of said members to the other, said connecting mean including an adjusting element rotatably carried by the rocker member and frictionally engaging the reciprocating member, said element and rocker member having cam surfaces coacting upon ro tation of said element with respect to said members for altering the operative relation of the members with respect to each other, and means including a cam and a cam follower connected with the reciprocative member and with the rocker member rendered effective during said movements of said members for rotating said adjusting element.

3. A self-adjusting valve actuating mechanism comprising a rocker member, a reciprocative member, means operatively connecting the rocker member and reciprocative member with each other for transmitting motion from one of said members to the other, said connecting means including an adjusting element rotatably carried by the rocker member and frictionally engaging the reciprocating member, said element and rocker member having cam surfaces coacting upon rotation of said element with respect to said members for altering the operative relation of the members with respect to each other, means for producing said movements of said members, a first operating means including a cam and a cam follower connected with the reciprocative memher and with the rocker member rendered efiective during said movements of said members for rotating said adjusting element to introduce slack in the valve actuating mechanism, and separate operating means connected with the adjusting element and with the rocker member and functioning independently of the first operating means adapted to actuate said element for taking up slack in the valve actuating mechanism.

4. A self-adjusting valve actuating mechanism comprising a rocker member, a reciprocative member, means operatively connecting the rocker member and reciprocative member with each other for transmitting motion from one of said members to the other, said means'including an adjusting element movable with respect to both of said members and functioning with a cam action to alter the operative relation between said members, means rendered effective by the movements of said members for positively rotating the recip rocative member in opposite directions, and means including coupling elements operatively connecting the reciprocative member with said adjusting element adapted to frictionally transmit the rotary movement of the reciprocative member to said adjusting element.

5. A self-adjusting valve actuating mechanism comprising an arm mounted to rock about a fixed axis, means for rocking said arm comprising a push rod mounted to reciprocate at one side of said axis, means operatively connecting the push rod with the arm in spaced relation to said axis, said latter means comprising an adjusting screw rotatably carried by the arm, means for actuating the adjusting screw to alter the operative spaced relation of the arm with respect to the push rod comprising a cam member connected with said arm and positioned in a plane intermediate the axis of rotation of the arm and said push rod, a cam follower connected with said push rod and actuated by said cam during said reciprocative and rocking movements of the push rod and arm for producing rotation of the push rod, and means frictionally transmitting the rotary movement of the push rod to said adjusting screw.

6. A self-adjusting valve actuating mechanism comprising an arm having an axis of rocking movement, an adjusting element mounted in said arm in spaced relation to said axis, means including cam surfaces operatively connected with the arm and with said adjusting element adapted upon'rotary movement of said element to eiiect axial movement thereof with respect to said arm, means including a reciprocative member having operative engagement with the adjusting element for producing rocking movement of said arm, and means including a cam and cam follower set into operation by the rocking movement of said arm for producing rotary movement of the adjusting element whereby an operative clearance is produced in said valve actuating mechanism.

7. A self-adjusting valve actuating mechanism comprising an arm having an axis of rocking movement, an adjusting element connected with said arm in spaced relation to said axis, means including cam surfaces connected with the arm and with said adjusting element adapted upon rotary movement of said element to efiect axial movement thereof with respect to said arm, means including a reciprocative member having operative engagement with the adjusting element for producing rocking movement of said arm, means including a cam and cam follower actuated by the rocking movement of said arm for producing rotary movement of the adjusting element to vary the operative relation of said arm with respect to said reciprocative member whereby an operative clearance is introduced in said valve actuating mechanism, and means including a spring connected with the adjusting element and with said arm for actuating said element in a direction to take up slack in said valve actuating mechanism.

8. A self-adjusting valve actuating mechanism comprising an arm having an axis of rocking movement, an adjusting element connected with said arm in spaced relation to said axis, means including cam surfaces connected with the arm and with said adjusting element adapted upon rotary movement of said element to efiect axial movement thereof with respect to said arm, means including a reciprocative member having operative engagement with the adjusting element for producing rocking movement of the said arm, means providing a cam surface arranged in fixed spaced relation to said axis, a cam follower carried by said arm and actuated by said cam during the rocking movement of said arm, and means associated with the adjusting element controlled by the action of said cam follower and by the combined action of said reciprocating and rocking movements for introducing slack in the valve actuating mechanism.

9. In a self-adjusting valve actuating mechanism, a plurality of operating parts including an arm having an axis of rocking movement, means including a clearance compensating unit for rocking said arm, means providing a cam surface arranged in fixed spaced relation with respect to said axis, a cam follower carried by said arm and actuated by the cam during said rocking movement of the arm, and means operatively connecting the cam follower with the clearance compensating unit of such a character that said unit is actuated by the cam follower for introducing slack in the valve actuating mechanism.

19. In a self-adjusting valve actuating mechanism, a plurality of operating parts including an arm having an axis of rockin movement, a clearance compensating unit connected with said arm in spaced relation to said axis, said unit comprising a clutch element rotatively mounted in said arm to have clutching engagement therewith, a screw element mounted in said clutch element adapted upon relative rotary movement of said elements to move axially with respect to said clutch element, means engaging said screw element for rocking said arm, means providing a cam surface arranged in fixed spaced relation with respect to said axis, cam follower means carried by said arm and operatively connected with said screw element adapted to be actuated by the cam during the rocking movement of the arm to effect operation of the clearance compensating unit for introducing slack in the valve actuating mechanism.

11. A self-adjusting valve mechanism, as defined in claim 10, having resilient means connected with the clutch element and with said arm adapted to actuate the clearance compensating unit to take up slack in the valve actuating mechanism.

12. In a self-adjusting valve mechanism, in combination, an arm having an axis of rocking movement, means for rocking said arm including an operating cam, ,a push rod operatively connected with said cam to be reciprocated thereby, said cam and push rod being arranged in onset relation with respect to each other, whereby said push rod is rotated by the cam when an appreciable pressure occurs between said push rod and cam, mean for operatively connecting the push rod with said arm including a clearance compensating unit actuated by the reciprocative movement of said push rod for rocking said arm, and means including cam elements actuated by the arm and by the reciprocative and rotary movements of said push rod for actuating the members or said clearance compensating unit for introducing slack in the valve actuating mechanism.

WILLIAM M. GOODWIN.

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