US2131507A

US2131507A - Valve operating mechanism

Info

Publication number: US2131507A
Application number: US12641A
Authority: US
Inventors: William M Goodwin
Original assignee: Individual
Current assignee: Individual
Priority date: 1935-03-23
Filing date: 1935-03-23
Publication date: 1938-09-27
Anticipated expiration: 1955-09-27

Description

Sept. 27, 1938. w. M GOODWIN 2,131,507

VALVE OPERATING MECHANISM Filed March 25, 1935 El- 8 m 4 l3 5 4 4 4 4 4 M 4 4 4 4 4 e z 4 4 b2 i 4 Z 29 32 l Z 4 F 4 32 3; 4p 2 29 Q5 R Patented Sept. 27, 1938 UNITED STATES PATENT OFFICE Application March 23,

9 Claims.

This invention relates to a valve operating mechanism and pertains more particularly to the actuating means for the usual spring closed poppet valve of an internal combustion engine of the class set forth in my Patent No. 1,609,711

dated December 7th, 1926.

In a'valve operating mechanism of the above mentioned class, it is a well known fact that considerable difiiculty is experienced in preventing 10 lost motion between the actuating means as a cam and the valve actuated thereby when said .Valve is in the closed position in engagement with its seat. This is due to variations inthe over-all length of the connecting parts introduced therein by temperature changes and it is difficult, therefore, to prevent tappet noises incident to such lost motion. The applicant is acquainted with many different devices which have been introduced in an endeavor to overcome this defect in the construction of internal combustion engines but in so far as'he is aware, these devices have either been impractical due todefects in mechanical construction or have been so expensive to construct as to render them com,-

mercially impractical.

It is one of the main objects of this invention to produce an improved valve operating mechanism for an internal combustion engine that will prevent lost motion between the operating cam and the valve actuated thereby and at the same time allow the valve to properly engage its seat over all working conditions.

Another object of the invention is to provide a valve operating mechanism adapted to take up any lost motion which may occur therein that is simple, durable and economical in construction and which is positive, automatic and 'eflicient in operation.

In carrying out the above mentioned objects 40 I have provided a motion transmitting mechanism incorporated in the valve operating mechanism which has relatively movable members for taking up lost motion between the operating cam and the valve stem and at the same time is self-acting to permit variations in the length of the associated parts, particularly the valve stem, due to expansion or contraction thereof caused by temperature changes.

A further object of the invention is to provide means for locking the relatively movable portions of the motion transmission mechanism to each other to prevent relative movement thereof during the opening of the valve and to unlock said portions as the valve approaches -or is in the closed position to permit necessary relative 1935, Serial No. 12,641

movement of the members to compensate for any variation in the length of the connections introduced by temperature changes or by other reasons. A still further object resides in providing a self-adjusting mechanism for transmitting motion from a cam to a poppet valve which will remain in the adjusted position during the opening and closing operation of the valve as long as there is no variation introduced in the length of the associated parts and thereby contribute to a maximum life of the device by reducing to a minimum the wear incident to parts having a relative movement.

Other objects and uses relating to specific parts of the mechanism will more fully appear in the following description taken in connection with the accompanying drawing in which:

Figure 1 is a vertical sectional view partly in elevation of a poppet valve, the adjacent portions of an internal combustion engine and my novel mechanism for transmitting motion from the operating cam to the valve.

Figure 2 is a detail horizontal sectional view on an enlarged scale taken on line 22, Figure 1.

Figure 3 is a fragmentary side elevation partly in section of the adjacent end portions of the valve stem and my novel motion transmitting and take-up mechanism as viewed from line 3-3, Figure 1.

Figure 4 is a vertical sectional view of the 1 upper end portion of the motion transmitting and take-up mechanism partly in elevation as shown in Figure 1 but on an enlarged scale.

Figure 5 is a vertical sectional view partly in elevation of the lower end of my novel motion transmission and take-up mechanism and the operating cam therefor taken at right angles to the views shown in Figure 1.

Although as will be readily understood, this invention is not limited in its application to an internal combustion engine and particularly to the valve mechanism therefor, I have illustrated in Figure 1 my novel transmission and take-up mechanism as I in connection with a poppet valve of an internal combustion engine 9 in which the valve 8 is opened and closed to and from its seat 10 by means of a cam II and a retracting spring I2 respectively. The valve 8 and retracting spring 12 may be of any well known construction but as shown the valve stem as I3 isreciprocally mounted in a vertically disposed guide 14 mounted in an extension I5 of the engine frame 9 while the'spring I2 is mounted on the valve stem and guide between the engine frame extension 15 adjacent the lower end of the guide opening and a retaining washer l6 on the valve stem adjacent the lower end thereof.

The cam H is secured to or made integral with a cam shaft l! which is journaled in the usual manner in the base iii of the engine. This cam may be of any desirable form capable of lifting the valve 3 from its seat l against the action of the spring i2 once during each revolution and as shown is of usual construction except that it is provided with a peripheral cam groove 20 in the lower side thereof substantially mid-way between the sides of the cam. This cam groove '20 is arranged diametrically opposite the high side of the cam in symmetrical relation therewith and is of slightly more than 180 in length for the purpose of effecting the operation of the locking mechanism included in my novel motion transmission and take-up mechanism for operatively connecting the cam with the valve stem in a manner which will hereinafter be more apparent.

The motion transmission and take-up mechanism I as illustrated in the drawing comprises a vertically disposed tubular plunger 24 mounted for reciprocative movement in a guide bearing 25 on the engine frame between the cam II and the valve stem I3 with its axis of movement in alignment with that of said valve stem. This plunger 24 is of considerably less length than the distance between the cam II and valve stem l3 and has fixedly secured to the lower end thereof a foot or contact member 21 to form an integral part of the plunger and adapted to contact with the cam ll.

In the upper end of the plunger 24 is adjustably mounted a tappet screw 23 which has the lower portion thereof provided with relatively coarse external threads 30 in threaded engagement with similarly constructed internal threads 3| provided in the upper end portion of the plunger 24. The upper end portion of the tappet screw 29 is reduced in diameter and is maintained in constant engagement with the outer or lower end of the valve stem l3 by a torsional spring 32 coiled about the upper end of the tappet screw with one end connected as at 33, Fig ure 2, to the screw to rotate therewith and the other end fixed to the upper end portion of the plunger 24, as at 34, Figures 1 and 3, to rotate with said plunger. The spring 32 is tensioned to constantly urge relative rotation of the plunger 24 and screw 29 in a direction to cause separation thereof by the screw threads 30 and 3i to increase the over-all length of said plunger and screw. In other words, the tappet screw isurged by the spring 32 to be rotated in a direction to move the screw axially toward the valve stem l3 and to rotate the plunger 24 in the opposite direction to effect the downward movement thereof toward the cam shaft H for maintaining said members in constant contact with the valve stem and cam I i respectively.

The angle of the screw threads 30 and 3| is preferably as shown substantially 45 to the axis thereof so that relative rotation of the tappet screw and plunger to produce relative axial movement thereof may be readily effected whether axial pressure is exerted at the upper end of the screw or at the lower end of the plunger.

While I have illustrated the threads extending at an angle of substantially 45 it is to be understood that this angle may be altered as desired so as to interpose whatever frictional resistance is required; that is, if the spring I2 is exceptionally highly tensioned, it may be desirable to arrange the threads 30 and 3| at an angle somewhere between 30 and 45 to the axis of the screw so as to reduce the tendency of said screw to be rotated by the action of the spring l2.

It will thus be understoood that while the spring 32 functions to produce relative rotation of the tappet screw 29 and the plunger 24 in one direction to increase the over-all length thereof, the axial pressure exerted on the tappet screw by the valve spring l2 tends to produce relative rotation of these members in the opposite direction to shorten the over-all length-thereof. In order, therefore, that the tappet screw and the plunger may be maintained or locked against relative rotation during the axial movement thereof and particularly when said members are being lifted by the action of the cam II to raise the valve 8 from its seat Ill, I have provided a novel locking mechanism which is controlled by the cam II and cam groove 20 for accomplishing thisresult.

This locking mechanism consists of a pair of

screw members

38 and 39, one of which as 38 is provided with external threads 40 and is mounted in a central bore 29' provided in the lower end portion of the tappet screw 29 with the threads 40 in meshing engagement with similarly constructed internal threads 42 provided in said bore. The upper end of the screw member 38 normally terminates some distance below the inner end of the bore 29 and an expansion spring 43 is mounted in said bore between the upper end of the member 38 and the bore 29' as shown in Figure 4 for exerting a constant downward pressure on the member 38.

The other screw member 39 is mounted in a central bore 21' provided in the contact member 21. The screw member 39 is provided with external screw threads 45 which are in meshing engagement with similarly constructed internal screw threads 46 provided in the bore 21. The pitch of the

screw threads

40 and 45 as shown in the drawing is substantially 60 so as to permit the ready relative rotation of the screw members intheir associated elements when axial pressure is applied to either end thereof and to fric- -tionally resist relative rotation of these screw members and the tappet screw 29 and plunger 24 during relative rotation of said screw and plunger to vary the over-all length thereof affected by the screw threads 30 and 3| in the manner hereinbefore described. However, it is to be understood that the angle of the

threads

40 and 45 may be so selected as to interpose whatever frictional resistance is required. The

screw members

38 and 39 are secured together by the tongue and slot connection 49 as illustrated in Figure l to cause said members to rotate in unison and at the same'time permit relative axial movement thereof. The lower end of the screw member 39 is somewhat reduced in diameter to form an extension 39' projecting below the threads 45 for engaging in the cam groove 20.

Operation Assuming that the cam shaft I1 is moving in the direction indicated by the arrow X, Figures 1 and-5, and that the high point of the cam is positioned at substantially right angles to the axis of the plunger 24 and valve stem I3 under which condition the valve 8 will be in the closed position in contact with the seat in. The lower end 39' of the screw member 39 will be in registration with the rear end portion of the cam groove 20 and may or may not be extended into v said cam groove in the manner illustrated in Figures 1 and 5, Then as the cam H is rotated, if the end 39 is in the groove 20, the lower end of the screw member 39 will be moved out of the cam slot and will be brought into and maintained in the plane of the lower end of the foot or contact member 21.

The engagement of the cam II with the contact member 21 will, of course, produce upward axial movement of the plunger 24 and the screw member 39 and at the same time the upper vertical movement of the plunger will be transmitted to the tappet screw 29 through screw threads 30 and 3| and thence to the valve stem i3 to lift the valve 8 from its seat l9. Inasmuch as this upward movement of the valve will be effected will be prevented from relative rotation during the axial movement thereof by the screw threads on the

screw members

38 and 39 owing to the frictional resistance ofiered thereby to such turning movement by the difference in the pitch or particular relative angular arrangement of the screw threads 40-42 and 30--3l and also to the fact that the screw member 39 is prevented from,

downward axial movement relative to the plunger 24. This relative axial movement of the screw member 391s prevented for the reason that the end 39' of the screw member 39 is always in con tact with the high portion of the cam H during the axial movement of the plunger 24 which holds the screw member 39 against being screw threaded downwardly or toward the cam ll relatively to the plunger 24 and tappet screw 29.

In other words, as looking

members

38 and 39 are held by cam ll against rotation in the direction of rotation of tappet screw 29 when the latter is being screw threaded into plunger 24,

any normal tendency of the tappet screw to roof the valve 8 to open the same upon each revolution of the cam shaft l1.

Now as the high portion of the cam H passes beyond the contact member 21 and said member engages the low portion of the cam, the cam groove 20 is brought into registration with the screw member 39 and if the valve stem l3 has been lengthened during the axial movement thereof due to expansion or other causes, the action of the spring l2 tends to force the tappet screw 29 downwardly and produce relative rotation of the tappet scre and p unger 24 aga nst the action of the spring 32 to decrease the overall length thereof until the valve has reached the limit of its downward movement by the engagement thereof with the seat III. This relative rotation of the tappet screw and plunger will produce a corresponding rotation of the

screw members

38 and 39 and will thus cause the lower end 39-of the screw member 39 to enter the cam groove 20 to a greater or less degree which action is assisted by the spring 43. As the cam groove 20 again passes beyond the screw member 39 the lower end of said member will again engage the high portion of the cam H and be forced upwardly relatively to the plung 24 and thereby effect a turning movement of the screw member in the plunger and screw thread the

screw members

38 and 39 upwardly into the plunger and tappetscrew 29 respectively without affecting the over-all length of the plunger and tappet screw.

If, on the other hand, the over-all length of the plunger and tappetscrew is insufficient to maintain the tappet screw in contact with the valve stem l3 when the valve engages the seat l0 and the low portion of the cam II is in contact with the member 21, the spring 32 will rotate the tappet screw 29 in a direction to screw thread the same outwardly or upwardly from the plunger 24 and thereby increase the-over-all length of these members until the tappet screw again contacts the valve stem l3. As the over-all length of the plunger and tappet screw is thus increased, the

screw members

38 and 39 will remain practically in their lower position due to the action of the spring 43 as will be readily understood, and when relative rotation of the screw members is produced by the relative totation of the tappet screw and plunger any axial relative movement of the screw members pro duced thereby will be permitted by the tongue and slot connection 49 between said members. It is to be understood that when there is an easy sliding fit between the

screw members

38 and 39 and the tappet screw 29 and plunger 24 the spring 43 may be omitted, but when the spring is incorporated in the structure this spring is sufficiently light in structure so that when the over-all length of the plunger and tappet screw remains constant and any relative rotation of these members occurs, the

screw members

38 and 39 will remain in fixed relation thereto during each cycle of movement and will only move downwardly when the lower end 39' of the member 39 is in registration with the cam groove 20 upon relative rotation of the plunger and tappet screw in a direction to shorten the over-all length of these members.

It will now be understood that the over-all length of the motion transmission mechanism 1 will be automatically adjusted to assure a continuous connection between the cam l l and valve stem l3 and thereby prevent lost motion and noise incidental thereto and although I have shown and particularly described the preferred embodiment of my invention, I do not wish to be limited to the exact construction shown as various changes in the form and relation of the parts thereof may readily be made without departing from the spirit of the invention as set forth in the appended claims.

I cla m:

1. A valve operating mechanism comprising a plurality of valve operating members having movement relative to each other to increase or decrease the over-all length thereof, a continuously operating cam for intermittently -reciprocating said members to open and close the valve, means for locking said members against said relative movement throughout the reciprocating movement thereof including two holding elements operatively connected to transmit motion from one to the other, means for maintaining operative connection between each holding element and a respective valve operating member effective upon a decrease in the overall length of the valve operating members to positively produce movement of the holding elements relative to said members toward the cam to bring one of said elements into operative engagement with said cam, a second cam cooperating with said one of the holdin elem s during the inoperative portion of the cycle of movement of said first mentioned cam for releasing said locking means, and means rendered operative by the release of said locking means for adjusting said valve operating members relative to each other.

2. A valve operating mechanism comprising a plurality of axially reciprocating valve operating members, means for maintaining operative connection between the members so that upon relative rotation of themembers their over-all length will be increased or decreased, a cam for intermittently reciprocating the valve operating members to open and close the valve, co-acting looking elements arranged in co-axial relation with each other and having'axial movement relative to each other and to the reciprocating members toward and from the cam, screw means between each locking element and a respective one of said members effective upon said relative rotation of the members to decrease the over-all length thereof to positively move the elements relative to said members toward the cam, said cam having holding engagement with one of the locking elements during said intermittent move- I ment only for maintaining said elements and members against said relative axial movement, a second cam for releasing said locking elements at the end of the intermittent movement of the members, and means rendered operative by the release of said locking means for adjusting said reciprocating members relative to each other.

3. In a valve operating mechanism, in combination, a plurality of axially reciprocating valve operating members, means including screw threads for maintaining operative connection between the members so that upon relative rotation said members will be moved axially to increase or decrease the overall length thereof, a cam engaging one of the valve operating members for intermittently reciprocating said members, locking means for said valve operating members including two holding elements operatively connected to transmit rotary motion from one to the other, means including screw threads operatively connecting each of said elements with a respective one of the valve operating members, said latter screw threads being so constructed and arranged relative to the first mentioned screw threads that a decrease in the over-all length of the valve operating members will positively produce axial movement of the holding elements relative to said members to be engaged by the cam, a second cam for releasing said holding elements during the inoperative portion of the cycle of movement of the first cam, and means rendered perative by the release of said locking means f r adjusting said operating members relative to each other.

4. In a valve operating mechanism, in combination, a plurality of axially reciprocating valve operating members, means including screw threads for maintaining operative connection between the members so that upon relative rotation said members will be moved axially to increase or decrease the overall length thereof, a cam engaging one of the valve operating members for intermittently reciprocating said members, locking means for said valve operating members including a holding element, means maintaining operative connection between the holding element and two of the valve operating members whereby relative rotation of said members to decrease the overall length thereof will positively produce movement of the holding element from a retracted position at one side of the cam to an extended position into the path of movement of said cam, a groove in the cam adapted to register with the holding element for releasing the looking means at the end of the intermittent movement of the valve operating members, and means rendered operative by the release of said locking means for rotating the valve operating members to increase the overall length thereof.

5. A valve operating mechanism comprising, in combination, a plurality of valve operating members having movement relative to each other to increase or decrease the overall length thereof, means including a continuously operating cam engaging one of the valve operating members for intermittently reciprocating said members to open and close the valve, said cam having a peripheral groove in the lower side thereof, locking means for said operating members including a holding element mounted in said member engaged by the cam to be moved by said cam from an extended position beyond the member and within said cam groove to a retracted position within the member engaged by the cam, means maintaining operative connection between the holding element and at least two of said valve operating members effective during a decrease in the overall length of the members to positively produce movement of the holding element from said retracted to said extended position,

and means yieldingly urging relative movementperipheral groove in the low side thereof, locking means for said valve operating members including two holding elements operatively' connected to transmit motion from one to the other, means for maintaining operative connection between each holding element and a respective one of the valve operating members eifective during a decrease in the overall length of the members to positively produce movement of the holding elements relative to said members toward the cam, one of said holding elements being mounted to alternately register with the cam groove and to be engaged by the cam whereby the valve operating members are free to move relative to each other when the valve is closed and will be maintained against movement relative to each other during the opening and closing operation of the valve, and means yieldingly urging relative movement of the valve operating members to increase the overall length thereof.

7. A valve operating mechanism comprising a plurality of axially reciprocating valve operating members having screw-threaded connection with each other whereby upon relative rotation the over-all length thereof may be increased or decreased, a locking element having screw-threaded engagement with one of the valve operating members, the pitch of the screw-threads of said locking element being greater than the pitch of the screw-threads between said valve operating members, so that when the locking element is held against rotation the valve operating members will be maintained thereby against rotation with respect to each other, and means for reciprocating the valve operating members and for intermittently holding the locking element against rotation.

8. A device as in claim 7 having means rendered operative by the release of the locking element for producing relative rotation of the valve operating members.

9. A valve operating mechanism comprising a plurality of axially reciprocating valve operating members having screw-threaded connection with each other whereby upon relative rotation the over-all length thereof may be increased or decreased, a pair of locking elements splined to each other to rotate in unison and to have axial move ment relative to each other, each of said locking elements having screw-threaded engagement with a respective one of said members, the pitch of the screw-threads connecting said locking elements to said valve operating members being greater than the pitch of he screw-threads connecting the valve operating members to each other, so that when the locking elements are held against rotation the valve operating members will be maintained thereby against rotation with respect to each other, and means for reciprocating the valve operating members and for intermittently holding the locking elements against rotation.

WILLIAM M. GOODWIN.