US3298333A

US3298333A - Valve actuating mechanism with mechanical means for self-adjustment

Info

Publication number: US3298333A
Application number: US425558A
Authority: US
Inventors: Stephen F Briggs; Joseph F Nemechek
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-01-14
Filing date: 1965-01-14
Publication date: 1967-01-17
Anticipated expiration: 1984-01-17

Description

Jan. 17, 1967 s. F. BRIGGS ETAL 3,298,333

VALVE ACTUATING MECHANISM WITH MECHANICAL MEANS FOR SELF-ADJUSTMENT Filed Jan. 14, 1965 (I 4 W /llllllll l/gfl INVENTOR5 AJ-M mv-Mh ATTORNE Y United States Patent 3,298,333 VALVE ACTUATHNG MEQHANISM WITH ME- CHANICAL MEANS FOR SELF-ADJUSTMENT Stephen F. Briggs, R0. Box 1617, and Joseph F. Nemechek, 940 th 5t. 5., both of Naples, Fla. 33940 Filed Jan. 14, 1965, Ser. No. 425,558 3 Claims. (Cl. 12390) The present application is a companion to the application of Stephen F. Briggs, Serial No. 363,778, filed Apr. 30, 1964 and now Patent No. 3,189,011 allowed Dec. 2, 1964. As in the companion application above identified, it is an object of the present invention to provide a means for taking up play in the motion transmitting train between a valve lifter and a valve in an internal combustion engine or pump or compressor or the like.

Changes in temperature, and wear, bring about variations in relative dimensions which tend to create play in a valve operating train under some conditions of operation. In general, prior art devices for eliminating play have been designed on the theory that objectionable valve noise or slap occurs primarily in the course of the valve opening movement. Some prior art devices have even assumed that such play is essential and have approached the problem from the standpoint of reducing the impact between the parts when the circumstances are such that play exists in the train.

In the course of the work which has resulted in the invention of the copending application above identified, it has been found that it is unnecessary to have play under any conditions; that the objectionable noise occurs primarily when the control valve is seated rather than preliminary to its opening; and that a device functioning with a wedging action can be made to take up play under conditions such that play would tend to be established while, at the same time, it will maintain valve movement positively subject to control of its cam and may be self-adjusting in the opposite direction to permit an increase in over-all length of the train without holding the control valve open.

In the instant device, the adjustment is effected between the rocker arm and its fulcrum. Thus, the adjustment is remote from both the push rod and the valve stem. It is found that in this location self-adjustment of the parts for taking up play will occur with special facility.

In the exemplifications selected to illustrate the invention, the rocker arm has a generally spherical bearing surface fulcrumed upon a complementary convex bearing section which is mounted on a post intermediate the push rod and the valve stem and to which the rocker arm is held by valve spring pressure. An abutment on the post limits the reactive movement of the bearing sector axially of the post under thrust of the valve spring.

The present invention contemplates a wedge which is either movable transversely of the post or rotatively about the axis of the post for take-up adjustment purposes, the wedging action being subject to spring bias and the wedge having opposed surfaces related to valve spring pressures and the other factors mentioned in the companion application above identified.

In the drawings:

. FIG. 1 is a diagrammatic view largely in vertical section axially of the rocker arm, mounting post and the valve stem and push rod and fragmentarily illustrating a valve operating train.

3,298,333 Patented Jan. 17, 1967 FIG. 2 is a detail view taken on the line 2- 2 of FIG. 1, but showing a slight modification.

FIG. 3 is a fragmentary view comparable to a portion of FIG. 1 and showing a modified embodiment of the invention.

FIG. 4 is a view taken partially in plan and partially in axial section on the line 44 of FIG. 3.

FIG. 5 is a view similar to FIG. 3 showing a further modified embodiment of the invention.

FIG. 6 is a view taken in section on the line 66 of FIG. 5.

Referring to FIG. 1, a cylinder fragmentarily illustrated at 8 has a port 9 for a valve 10 conventionally biased toward its seat by a valve spring 12 which encircles the valve stem 14 and bears against the collar 16 mounted on valve stem 14.

The valve is displaced from its seat in a manner which is generally conventional. Motion is communicated to the valve stem from cam shaft 18 by means of cam 20, cam follower 22, push rod 24 and rocker arm 26. The latter may he of channel-shaped cross section and formed integrally with a bearing portion 28 resting on the upper end of the push rod and another bearing portion 30 resting on the upper end of the valve stem 14.

Intermediate the bearing

portions

28 and 30, the rocker arm 26 is ported at 32 to receive the fulcrum post 34. The post carries a downwardly convex bearing member 36 which is engaged by a complementary concave socket portion 38 of rocker arm 26. As will be evident, the pressure of the valve spring 12 not only seats valve 10 but is intended to hold rocker arm 26 snugly against the downwardly convex bearing member 36 and thereby to hold the push rod 24 securely against the follower 22 and to hold the follower securely against the cam 20..

Positive control of valve opening and closing movement depends on elimination of play from the motion transmitting train. Upward reaction of the rocker arm on bearing member 36 is sustained by an abutment 40 which may comprise a nut threaded to the post 34 for adjustment and locked against accidental rotation by a cross pin 42.

The present invention contemplates a device for taking up lost motion in the valve train by means of wedge 44 and complementary wedge member 46. In the device shown in FIG. 1 and FIG. 2, the top surface 48 of wedge member 44 is normal to the avis of post 34 and this is also true of the lower surface 50 of the complementary wedge member 46. The complementary wedge member 46 is precluded from movement diametrically of post 34, the post passing through an aperture 52 of wedge member 46. Wedge member 44, on the other hand, is movable diametrically of post 34, being provided with a slot at 54 through which the post passes. The lower surface 50 of wedge member 46 is in face contact with the top of the downwardly convex bearing member 36. Upward movement of the face 48 of wedge member 44 is precluded by the nut 40. A spring 56 which, in the exemplification of FIG. 1 is a tension spring, subjects the wedge member 44 to a constant bias in a direction tend- .wedge surface 60 of member 46 to the right as viewed in FIG. 1 and FIG. 2 in a direction to take up slack. As shown in FIG. 2, I may use two springs 56a and 56b instead of the single spring shown in FIG. 1, the arrangement being otherwise closely comparable.

When the parts are cold, there is normally considerable l 3 lost motion in a co-nventional valve train and there is substantial valve noise in the seating of the valve 1% because, due to the slack, the valve spring 12 does not hold the cam follower 22 tightly to the surface of cam 20 to control the seating movement of the valve. Desirably, the valve should approach its seat smoothly to reach a fully seated position as the nose of cam 20 passes from beneath the follower 22. In the instant device, self-adjustment resulting from the operation of the wedge member 46 as sures that this will occur.

Upon each seating movement of the valve, as the spring 12 is expanded to the full extent that expansion is permitted to it, there is a slight reaction or bounce, possibly due to a wave of slight over-expansion of the spring, in consequence of which the parts are relatively free of load. It is at this time that self-adjustment between the

complementary cam members

44 and 46 will normally ccur in the direction in which there is residual imbalance between the bias of spring 12 or the opposing bias of the spring 56. This self-adjusting movement has been found to be facilitated when the cam members are mounted on the post 34 intermediate the valve stem 14 and the push rod 24.

As explained in the companion application above identified, a very effective angle between the wedge surfaces of the

complementary elements

44 and 46, respectively, when using a 90# valve spring and a 9# cam spring 56, is approximately 8 to 10. However, as explained in the copending application aforesaid, this angle will vary according-to the coefficients of friction of materials used, as related to the spring bias employed at 12 and 56. It may also vary according to the lift of cam 20. Thus aside from indicating a particular range of angles which has been found to be effective for the purpose under particular conditions and using conventional materials, it can only be stated that apparently the cam angle is critical and must lie within a few degrees. The cam angle may be varied Within the limits which are appropriate to the requirements of use. At all times closing as well as open: ing should be subject to the positive control of the cam with no resilience or lost motion.

Because of the fact that the lower bearing surface upon which the rocker arm fulcrums is generally spherical, it is possible to provide one of the two Wedging surfaces at 6% on a downwardly convex bearing member 360 which has a conical opening at 540 to receive the post 34 while permitting the bearing member 36% not only to oscillate but to rotate with respect to the post (FIGS. 3 and 4). In this construction, the bearing member 36%] has a radial spring anchorage 64 offset, with respect to the post 34, and to which the tension spring 560 is connected. As shown in FIG. 4, the other end of tension spring 560 is anchored at 66 to the end of rocker arm 26, being identical in this regard with the anchorage provided in FIG. 2 for spring 56. The wedge member 460 with a surface 580 complementary to the wedge surface 660 is, in this embodiment, splined at 68 to the groove 70 of post 34. The arrangement permits of relative rotative movement of the wedge element 46f with regard to the wedge surface of the bearing member 360 under bias of spring 560 to take up slack in the motion transmitting train. Because the motion is rotative, there will be some oscillation of the spherically convex bearing member 36%), this being accommodated by the tapered opening 540.

FIGS. 5 and 6 suggest merely that a compression spring may be used in lieu of a tension spring for biasing the wedge members for relative movement in a direction to take up lost mot-ion. In other respects, the structure shown in FIGS. 5 and 6 is very closely comparable to that of FIGS. 1 and 2. The rocker arm 26 may be identical and so may the downwardly convex bearing member 36 and socket provided therefor at 38 in the rocker arm. The reaction seat provided by nut 40 and the locking pin at 42 are likewise identical. The wedge member 442 coacts with complementary wedge member 462 in a manner closely comparable to that above described but the biasing spring is a compression spring 562 which is disposed in the elongated slot 542 of Wedge member 442, being seated at its outer end against a portion of the wedge member and at its inner end against the post 34. There is a bushing shown at 74. The use of a bushing of appropriate material and frictional characteristics is a convenient way of assuring proper automatic self-adjustment of the parts under conditions when it may not be desirable to change the bias of the valve spring 12 or the bias of the Wedge spring 56, or to make other adjustments.

In all of the devices herein disclosed, Wedging structures intervening between the rocker arm and the mounting post therefor, are used to take up play, self-adjustment being consequent upon the seating of the controlled valve while the system is relatively free of load and desirably while the system is subject to vibration. In all of the devices disclosed, the ratio between the wedge spring bias, the valve spring bias, the angle of the wedge surfaces, and the coeflicients of friction of the parts used is such that the device is self-adjusting both in a direction to take up slack and in a direction to accommodate increase in over-all length of the train. Throughout the range of relative movement of the coacting wedges, the angle is kept constant, or at least is not permitted to vary beyond the critical limits which, in any given valve gear, are required for self-adjustment in both directions.

Thus, the valve operation is controlled positively by the cam both in valve opening and valve closing movements and no clearance is permitted in the gear at any time.

We claim:

1. Valve gear mechanisms for controlling the unseating and seating of a valve having a stem and a valve seating spring, said mechanism comprising the combination with the valve stem and spring and a push rod having an actuator, of a rocker arm bearing on the push rod and the valve stem, a rocker arm post intervening between the push rod and the valve stem and on which the rocker arm is mounted for oscillation, bearing means movable axially on the post and having a downwardly convex surface for which the rocker arm has a complementary concave hearing surface held to the convex surface of the bearing means by the bias of the valve spring, an abutment fixed on the post above said bearing means, and means for the automatic self-adjustment of the over-all length of said mechanism both in a direction to increase the effective length thereof and to decrease the effective length thereof and comprising relatively movable members providing a pair of relatively movable wedge surfaces, one of said members being movable with respect to the post, and the other of said members being relatively fixed, both of said members being confined between the bearing means and the said abutment, a wedge biasing spring acting on the said member which is movable with respect to the post, the direction of bia exerted thereby on said member being such as to exert on said rocker arm a force in opposition to the bias of the valve spring on the rocker arm, the said wedging surfaces having an angle within narrow critical limits and so related to the coefiicient of friction and to the bias of the valve spring and to the bias of the wedge biasing spring that displacement of the push rod by its actuator in a valve unseating direction is transmitted positively to effect predetermined unseating displacement of the valve, the entire seating movement of the valve subject to the bias of the valve spring being transmitted positively through said mechanism to the push rod, whereby the push rod positively controls valve seating movement, the self-adjustment occurring when said mechanism is relatively free of load consequent upon the seating of the valve, two tension springs being connected between the movable Wedge member and the rocker arm to constitute the wedge biasing spring.

2. Valve gear mechanism for controlling the unseating and seating of a valve having a stem and a valve seating spring, said mechanism comprising the combination with the valve stem and spring and a push rod having an actuator, of a rocker arm bearing on the push rod and the valve stem, a rocker arm post intervening between the push rod and the valve stem and on which the rocker arm is mounted for oscillation, bearing means movable axially on the post and having a downwardly convex surface for which the rocker arm has a complementary concave bearing surface held to the convex surface of the bearing means by the bias of the valve spring, an abutment fixed on the post above said bearing means, and means for the automatic self-adjustment of the over-all length of aid mechanism both in a direction to increase the effective length thereof and to decrease the effective length thereof and comprising relatively movable members providing a pair of relatively movable wedge surfaces, one of said members being movable with respect to the post, and the other of said members being relatively fixed, both of said members being confined between the bearing means and the said abutment, a wedge biasing spring acting on the said member which is movable with respect to the post, the direc-- tion of bias exerted thereby on said member being such as to exert on said rocker arm a force in opposition to the bias of the valve spring on the rocker arm, the said wedging surfaces having an angle with-in narrow critical limits and so related to the coefiicient of friction and to the bias of the valve spring and to the bias of the Wedge biasing spring that displacement of the push rod by its actuator in a valve unseating directionqis transmitted positively to effect predetermined unseating displacement of the valve, the entire seating movement of the valve subject to the bias of the valve spring being transmitted positively through said mechanism to the push rod, whereby the push rod positively controls valve seating movement, the self-adjustment occurring when said mechanism is relatively free of load consequent upon the seating of the valve, the movable member having a slot through which the post passes and which accommodates relative movement of said last member diametrically of the post, said Wedge biasing spring comprising a compression spring disposed in the slot and bearing at one end against said last mentioned member and at the other end against said post, said compression spring acting on said last member in a direction to urge said bearing means away from the abutment on the post.

3. Valve gear mechanism for controlling the unseating and seating of a valve having a stem and a valve seating spring, said mechanism comprising the combination with the valve stem and a spring and a push rod having an actuator, of a rocker arm bearing on the push rod and the valve stem, a rocker arm post intervening between the push rod and the valve stem and on which the rocker arm is mounted for oscillation, bearing means movable axially on the post and having a downwardly convex surface for which the rocker arm has a complementary concave bearing surface held to the convex surface of the bearing means by the bias of the valve spring, an abutment fixed on the post above said bearing means, and means for the automatic self-adjustment of the over-all length of said mechanism both in a direction to increase the effective length thereof and to decrease the effective length thereof and comprising relatively movable members providing a pair of relatively movable wedge surfaces, one of said members being movable with respect to the post, and the other of said members being relatively fixed, both of said members being confined between the bearing means and the said abutment, a wedge biasing spring acting on the said member which is movable with respect to the post, the direction of bias exerted thereby on said member being such as to exert on said rocker arm a force in opposition to the bias of the valve spring on the rocker arm, the said wedging surfaces having an angle within narrow critical limits and so related to the coefficient of friction and to the bias of the valve spring and to the bias of the wedge biasing spring that displacement of the push rod by its actuator in a valve unseating direction is transmitted positively to effect predetermined unseating displacement of the valve, the entire seating movement of the valve subject to the bias of the valve spring being transmitted positively through said mechanism to the push rod, whereby the push rod positively controls valve seating movement, the self-adjustment occurring when said mechanism is relatively free of load consequent upon the seating of the valve, the bearing means movable axially on the post being also rotatable with respect to the post and having an opening through which the post passes and which is sufficiently larger than the post to accommodate both tilting and rotative movements of the bearing means with respect to the post, the said bearing means comprising one of said members and having on is upper face one of the wedge surfaces aforesaid, the Wedge biasing spring having an anchorage to the bearing means at a point radially offset from the post and having another anchorage remote from the first mentioned anchorage whereby the bias of the wedge biasing spring tends to rotate the bearing means with respect to the post and the relatively fixed member.

References Cited by the Examiner UNITED STATES PATENTS 1,531,909 3/ 1925 Engemann 123-90 1,903,078 3/1933 Woolman 1239O 2,493,783 1/1950 Stancliff 12390 2,845,053 7/1958 Humphreys 123--90 2,962,011 11/ 1960 Rosenberger 12390 3,009,450 11/ 1961 Engemann 123-90 MARK NEWMAN, Primary Examiner.

AL LAWRENCE SMITH, Examiner.

Claims

1. VALVE GEAR MECHANISMS FOR CONTROLLING THE UNSEATING AND SEATING OF A VALVE HAVING A STEM AND A VALVE SEATING SPRING, SAID MECHANISM COMPRISING THE COMBINATION WITH THE VALVE STEM AND SPRING AND A PUSH ROD HAVING AN ACTUATOR, OF A ROCKER ARM BEARING ON THE PUSH ROD AND THE VALVE STEM, A ROCKER ARM POST INTERVENING BETWEEN THE PUSH ROD AND THE VALVE STEM AND ON WHICH THE ROCKER ARM IS MOUNTED FOR OSCILLATION, BEARING MEANS MOVABLE AXIALLY ON THE POST AND HAVING A DOWNWARDLY CONVEX SURFACE FOR WHICH THE ROCKER ARM HAS A COMPLEMENTARY CONCAVE BEARING SURFACE HELD TO THE CONVEX SURFACE OF THE BEARING MEANS BY THE BIAS OF THE VALVE SPRING, AN ABUTMENT FIXED ON THE POST ABOVE SAID BEARING MEANS, AND MEANS FOR THE AUTOMATIC SELF-ADJUSTMENT OF THE OVER-ALL LENGTH OF SAID MECHANISM BOTH IN A DIRECTION TO INCREASE THE EFFECTIVE LENGTH THEREOF AND TO DECREASE THE EFFECTIVE LENGTH THEREOF AND COMPRISING RELATIVELY MOVABLE MEMBERS PROVIDING A PAIR OF RELATIVELY MOVABLE WEDGE SURFACES, ONE OF SAID MEMBERS BEING MOVABLE WITH RESPECT TO THE POST, AND THE OTHER OF SAID MEMBERS BEING RELATIVELY FIXED, BOTH OF SAID MEMBERS BEING CONFINED BETWEEN THE BEARING MEANS AND THE SAID ABUTMENT, A WEDGE BIASING SPRING ACTING ON THE SAID MEMBER WHICH IS MOVABLE WITH RESPECT TO THE POST, THE DIRECTION OF BIAS EXERTED THEREBY ON SAID MEMBER BEING SUCH AS TO EXERTED ON SAID ROCKER ARM A FORCE IN OPPOSITION TO THE BIAS OF THE VALVE SPRING ON THE ROCKER ARM, THE SAID WEDGING SURFACES HAVING AN ANGLE WITHIN NARROW CRITICAL LIMITS AND SO RELATED TO THE COEFFICIENT OF FRICTION AND TO THE BIAS OF THE VALVE SPRING AND TO THE BIAS OF THE WEDGE BIASING SPRING THAT DISPLACEMENT OF THE PUSH ROD BY ITS ACTUATOR IN A VALVE UNSEATING DIRECTION IS TRANSMITTED POSITIVELY TO EFFECT PREDETERMINED UNSEATING DISPLACEMENT OF THE VALVE, THE ENTIRE SEATING MOVEMENT OF THE VALVE SUBJECT TO THE BIAS OF THE VALVE SPRING BEING TRANSMITTED POSITIVELY THROUGH SAID MECHANISM TO THE PUSH ROD, WHEREBY THE PUSH ROD POSITIVELY CONTROLS VALVE SEATING MOVEMENT, THE SELF-ADJUSTMENT OCCURRING WHEN SAID MECHANISM IS RELATIVELY FREE OF LOAD CONSEQUENT UPON THE SEATING OF THE VALVE, TWO TENSION SPRINGS BEING CONNECTED BETWEEN THE MOVABLE WEDGE MEMBER AND THE ROCKER ARM TO CONSTITUTE THE WEDGE BIASING SPRING.