US2521176A - Valve gear for operating poppet valves of internal-combustion engines - Google Patents

Description

Sept. 5, 1950 A. o. KUTZ 2,521,176 mm: GEAR FOR OPERATING POPPET VALVES 0F INTERNAL-COMBUSTION mamas Filed Sept. 16, 1947- 2 Sheets-Sheet 2 KUTZ .INVENTOR.

FIG.

Patented Sept. 5, 1950 VALVE GEAR FOR OPERATING POPPET VALVES F INTERNAL-COMBUSTION mamas Arthur 0. Kutz. Buffalo, N. Y., aoaignor to Worthington Pump and Machinery Corporation, Harriaon, N. J., a corporation of Delaware Application September 16, 1947, Serial No. 774,332

' Claims.

1 This invention relates to mechanisms for operating reciprocating valves and, in particular,

' refers to means for eliminating both transverse forces on the valve stems and lost motion between the valves and their operating mechanism.

It will be recognized, even by those not in the art, that in actuating a poppet valve it is highly desirable to apply a force which has no component transverse to the axis of the valve since such side thrust may cause suihcient wear on the valve guide and'stem to result in serious operating difllculties. Nevertheless, it is almost universal practice in the construction of internal combustion engines to actuate the valves by -means of pivoted rocker arms which, of course,

apply forces having components parallel and transverse to the valve axes. Aside from ignoring it, the problem of side thrust thus presented can be solved in two ways; first, by designing the valve actuating mechanism so that the trans verse component is so small as to'have no appreciable effect during the designed life of the engine, and, second, by providing means to absorb or withdraw the transverse component completely so that only an axial force is transmitted to the valve stem. The present invention is in accordance with the second method whereby side thrust on the valve is completely eliminated.

Another problem, which is accentuatedby the expansion and contraction of parts associated with an internal combustion engine, is that of lost motion or slack between the rocker arm and the valve. This has been more or less satisfactorily solved by those who have provided the art with so-called lash adjusting mechanisms. In their preferred form these comprise, in essence, pressure loaded pistons which bear on the ends of the valve stems. However, in the past, when the lash adjusters have been used with the rocker arm type of valve operating mechanism, they have been mounted in movable bores so that they simply transmit whatever forces are applied to them. If side thrust was to be removed, suitable means therefor had to be incorporated in the linkage between the rocker arm and the lash adiusters.

The concept of the present invention is to arrange the lash adjusters so that they perform the double function of eliminating lost motion and of absorbing the. transverse component of rocker arm motion. To this end they are mounted in a stationary bore which may be in the engine block or head or in a bracket attached thereto. The side thrust applied to the lash adjuster is thus transmitted to the walls of the bore inst ad. it

to the valves which, therefore, receive only direct axial thrust. With this arrangement of the lash adjusters there may be associated a novel combination of pivoted pusher rods for actuating the adjusters and a loosely mounted arm for actuating the pusher rods, the function of this combination being to decrease the side thrust while transmitting rocker arm forces to the lash adjuster. I

The invention consists in various features of construction and arrangements of parts which will be described in connection with the preferred embodiments illustrated in the drawings in which Figure 1 is a vertical sectionof a portion of an engine cylinder and shows the invention applied to a rocker arm mechanism for operating a single valve.

' Figure 2 is similar to Figure 1 and shows the invention applied to a rocker arm mechanism for operating dual valves.

Figure 3 is a selected plan view along the line 3-3 of Figure 2.

Figure 4 is a side elevation of a bracket which may be used to support certain elements embodied in the invention.

In Figure 1 the invention is embodied in an engine I having a cylinder 2 with a reciprocal valve 3 which has a stem 4 mounted'in a guide 5. The valve 3 is yieldably biased to a closed position by means of a spring 6 which is compressed between the combined capand spring retainer 1, fixed to the top of the valve stem 4, and a suitable stationary part of the engine I circumjacent the valve guide 5, as shown at 8.

Movements of the valve 3 are actuated in the first instance by the usual rotary cam 9. Variations in the radii of the cam 9 are transmitted through the usual cam roller or follower iii to the,

rocker arm I I which, in response, rocks about its pivotal mounting i2 in the upright support l3 that is fixed to the engine I.

At the valve end, the rocker arm I i preferably, but not necessarily, carries a rocker push rod H. The push rod I4 is pivoted to the rocker arm at l5 and has its lower, "pushing extremity l5 convexly curved on a large radius. It is desirable that the valve end of the arm ll be forked and the rod H be mounted within its legs so that there is but a slight clearance ll between the side of rod M and the end wall of the bifurcation. This provision allows only a limited pivotal movement of the push rod i4 and insures operativeness of its extremity It.

The push rod It bears upon the top of the lash adjuster device 20, .This device bears upon the cap I on the valve stem 4 to comprise the last a the which transmit the signals of cam 9 into reciprocal movement of the valve 3. The lash adjuster chosen for illustration is well known to the art and comprises a cylindrical housing 2| which has a recess 22 in its lower end. A piston 22 is slidably mounted in the recess 22 and re strained excessive movement by a lock ring 24 in the wall of the cylinder 2|. It is the lower end of the piston 23 which bears on the cap 1. The lash adjuster is actuated to prevent slack and lost motion by means of pressure fluid which is admitted to the recess 22 and top of piston 23 through the ports 25.

It is to be realized that the invention may embody any-type of lash adjuster which may be broadly construed as the equivalent of the construction just described.

The lash adjuster 2. is mounted in a guide support which is stationary. This guide support may berendered stationary in any of a number of ways. as those in the art will realize, but in the preferred form it is formed on the end of the arm II which depends from the rocker arm support II. The guide support has a bore which is coaxial with the valve 3 and this may, if desired, be provided with the spaced liners 22. Pressure fluid to actuate the lash adjuster 2|, usually oil from the engine lubricating system, is admitted to the guide support 30 by means of a suitable conduit 33 connected to the port 34 in the support walls. As shown, the lash adjuster 2| is mounted in the guide support 30 so that the cylinder 2| is closely fitted to, but reciprocal in, the liners 52. The ports 25 and I4 and the space between the inner ends of the liners 32 are adjusted so that oil may reach the recess 22 from line 35 in any suitable position of the cylinder 2|.

It has been indicated above that an object of the present invention is to eliminate side thrust on the valve 3 due to the motion of the rocker arm II. A mere inspection of the construction in Figure 1 will now show that this has been accomplished since the cylinder 2| and piston 23 are constrained by the stationary guide support 25 to move only in a direction coaxial with the valve 2. Thus, the piston 25 can apply only direct axial thrust to the valve cap I, providing, of course, that their line of engagement is normal to the axis of the valve as shown in Figure 1. Transverse forces applied by the push rod I to the lash adjusted 20 are transmitted through the guide support I. to the arm SI and support II.

In Figure 2 the invention is embodied in an engine 5| having a cylinder 52 with dual reciprocal valves 53 which have stems 54 mounted in guides 55. The valves 53 are yieldably biased to a closed position by means of springs 55 which are compressed between the retainers 51, fixed to the ends of the valve stems 54, and suitable stationary parts of the engine 5| circumjacent the valve guides 55 asshown at 55.

Movements of the valves 53 are actuated in the first instance by the usual rotary cam 55. Variations in the radii of the cam 59 are transmitted through the usual cam follower or roller 60 to the rocker arm 5| which, in response, rocks on its pivotal mounting 62 in the upright support 52 that is fixed to the engine 5|.

The usual movable T-shaped bridge 65 is connected at its midpoint to the valve end of the rocker arm by means of a ball and socket joint 65. The outer ends of the bridge 65 are forked and carry the rocker push rods 61 which are pivotally mounted as shown at 58. As in Figure 1.

slight clearances II are provided between the sides of the push rods 51 and the slotted bridge ends to limit the angular movement of the rods. The lower extremities of the rods 01 are convexly curved in the same manner as rod I, previously described.

The rods I! bear upon the lash adjusters II which are no different than adjuster II which has been described in connection with Figure 1. Thus, they comprise cylinders H having recesses 12 with pistons 13 held therein by the lock rings 14. Pressure fluid to actuate the lash adjusters III is admitted through the ports 15 to the re cesses 12. The pistons 13 bear upon the top ends of the valve stems 54 to apply forces thereto.

The lash adjusters 10 are mounted in stationary guide supports 80. These may, if desired, have spaced liners 82 and have ports 84 for the admission of pressure fluid through conduits I2. As before, the cylinder II is carefully fit for reciprocating movement in the liners l2 and the ports 84 communicate with the recesses I2 and pistons 13 through-ports 15.

Though the invention is not so limited, the guide supports are conveniently parts of a bracket 90. This bracket, which appears most clearly in Figures 3 and 4, is fixed to the engine 5| by means of bolts (not shown) through its flange Si and upright body section 92. The guide supports 80 are fixed to and suitably positioned upon the body section 92 so that they project over and are coaxial with the valves 53.

It is also convenient to mount the bridge 55 on the bracket 90. For this purpose the bracket has a central flange 54 at its lower end which carries a bushing 95. 96 of the T-bridge is mounted in the bushing 95 and the dimensions are arranged so that it is a loose flt. The bridge 55 is yieldably biased upward toward the rocker arm 5| by a compressed spring 81 encircling the shaft 96 between the top of the bridge and a washer 58 resting in an annular recess about the bushing 95.

As was the case with the device of Figure 1, an important feature of the construction of Figure 2 is the stationary guide bore 80 for each lash adjuster 10. Because of this construction, the lash adjusters 10 not only eliminate lost motion in accordance with the prior art but also eliminate transverse forces clue to the motion of the rocker arm 5| so that only direct axial forces are applied to the valves 53.

Another important feature of the device of Figure 2 is the loosely mounted, semi-floating T- bridge 65, particularly, when used in conjunction with the pivoted pusher rods 61. The bridge 65 may be moved somewhat in a transverse direction and thus adjusts itself to non-axial loading by the rocker arm 6|. This reaction reduces the transverse component of rocker arm force which is transmitted to the push rods 51. Since the push rods 61 are pivotally mounted at 58 and convexly curved on their lower ends, they tend to remain axially aligned with the valves 53 despite the tilting of the bridge 65. The outcome of the combined action of the floating bridge 55 and the pivoted, convex push rods 61 is thus to decrease to some extent the transverse force applied to the lash adjusters 10.

In addition to reducing the number of parts and providing a more economical construction. the present construction has not only removed side thrust on the valves but has also reduced the inertia of the rocker arms by mounting the lash adjusters in stationary guides. This ar- The central leg or shaft rangement also eliminates the necessity for running oil conduits through the rocker arm and bridge in order to actuate the lash adjusters. In the present invention, the lash adjusters can be connected directly to the source of pressure fluid, as shown by conduits 33 and 83.

As set forth above, except as claimed, it is not intended to limit the invention to the specific construction illustrated and, in particular, it will be recognized that it can be applied to a rocker arm mechanism for operating more than two valves of various types or dispositions.

What is claimed is:

1. In an internal combustion engine having a cylinder, reciprocable valves for said cylinder, a rocker arm for providing valve opening forces, means for pivotally mounting said rocker arm on said cylinder, said means provided with station ary bores therein in axial alignment with said valves, reciprocable lash adjusters slid-ably fitted in said bores for transmitting axial forces only to said valves and provided with flat force receiving surfaces, means operatively connecting saidrocker arm to said lash adjusters including, a movable bridge operatively connected to said rocker arm, arms on said bridge provided with pivotally mounted push rods having convex surfaces in engagement with said flat force receiving surfaces of the lash adjusters to allow substantially tangential contact therewith at all times, a stem on said bridge to loosely mount said bridge on said cylinder in parallel alignment with said bores to allow a relatively small degree of transverse movement in said bridge whereby substantially axial forces will be delivered to said lash adjusters for opening said valves.

2. In an internal combustion engine having a cylinder, reciprocable valves for said cylinder, a rocker arm for providing valve opening forces, means for pivotally mounting said rocker arm on said cylinder, said means provided with stationary bores therein in axial alignment with said valves, reciprocable lash adjusters slidably fitted in said bores for transmitting axial forces only to said valves and provided with flat force receiving surfaces, means operatively connecting said rocker arm to said lash adjusters including, a movable bridge operatively connected to said rocker arm, arms on said bridge provided with pivotally mounted push rods having convex surfaces in engagement with said fiat force receiving surfaces of the lash adjusters to allow substantially tangential contact therewith at all times, means providing a stationary bore for said bridge which is parallel to the other bores, a. stem on said bridge loosely mounting said bridge in said bore to allow a relatively small degree of transverse movement on said bridge whereby substantially axial forces will be delivered to said lash adjusters for opening said valves.

3. In an internal combustion engine having a cylinder, dual valves for said cylinder, reciprocable hydraulic lash adjusters engaging the ends of said valves, 1:. support fixed to said engine, said support having bores coaxial with the valves and of substantially the same diameter as said lash adjusters, said lash adjusters being slidably mounted for transmitting axial forces only to said valve, 9. T-bridge having arms projecting over said lash adjusters, said lash adjusters having force receiving ends comprising plane surfaces normal to the valve axes, push rods pivotally connected to said bridge arms and having convex surfaces engaging said adjuster force receiving ends, said T-bridge having a stem, said support fixed to said engine having a bore slightly larger than said stem, said bore being parallel to and between said adjuster bores, said bridge being mounted in said bore to allow a small degree of transverse movement of said bridge, a rocker arm providing valve opening forces, said T-bridge being connected to said rocker arm to receive valve opening forces therefrom, and spring means urging said bridge against said rocker rm and valve opening forces.

4. The combination with an internal combustion engine having a cylinder, of a plurality of valves in said cylinder, valve cams for said valves, and at least one support between said valves and said valve cams, a rocker arm pivotally mounted on said support and having one end engaging said cam and the other end extending over said valves, a semi-floating spring mounted T bridge loosely mounted on the end of said rocker and extending over said valves, and a support having stationary guide bores in alignment with said valves between said T bridge and said valves, lash adjusters closely fitted to said bores, said adjusters operatively connected to the T bridge and to the end of said valve, a central flange on said support, a bushing in said flange to loosely receive said T bridge so that it may be moved in a somewhat transverse direction to adjust itself to non-axial loading by the rocker arm, said T bridge in cooperative relationship with said support whereby only axial thrust is transmitted from said rocker arm to said valve.

5. In an internal combustion engine having a cylinder, a plurality of reciprocable valves for said cylinder, a rocker arm for providing valve opening forces, means for pivotally mounting said rocker arm on said cylinder, said means provided with stationary bores thereon in alignment with said valves, a movable bridge operatively connected to said rocker arm including, arms thereon substantially perpendicular to the axial line of said bores, a main stem substantially parallel to said bores, and convex face push rods pivotally mounted on the ends of said bridge arms, said main stem loosely mounted in said cylinder to allow said bridge to move a, relatively small amount in the direction transverse to the axial valve opening forces of said rocker arm, reciprocable lash adjusters slidably mounted in said bores for engagement at one end with one of said valves and at the other end with one of said push rods, said movable bridge and said lash adjusters so constructed and arranged that the valve opening forces received from said pivotal Push rods will have a small transverse component of force and only the axial component of said force will be delivered to said valves by the lash adjusters.

ARTHUR O. KUI'Z.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA'I'ENTS Number Name Date 1,687,911 Vincent Oct. 16, 1928 1,696,866 Seaman Dec. 25, 1928 1,798,938 Hallett Mar. 31, 1931 1,905,888 Berry Apr. 25, 1933 1,996,807 Hallett Apr. 9, 1935 2,054,928 Church Sept. 22, 1936 2,380,051 Kettering July 10, 1945 2,411,775 Bronander Nov. 26, 1946

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