US2411775A - Valve mechanism - Google Patents

Description

NOV. 25., 19.46 w. B. BRONANDER, JR I 2,411,775

' VALVE MEGHANISM Filed'July 21, 1944 f 31 Jdf/ ff INVENTOR Patented Nov. 26, 1946 `Wilhelm B. Eronander, Jr., Montclair, N. J., assigner otono-half to Wilhelm B. .Bronanden Sr., Montclair, N. J.

ApplicationvJuly 21, 1944, Serial No..545,996

This invention relates to valve mechanisms for internal combustion engines and particularly to a method of balancing valve operating mechanisms. y

In the standard valve actuating mechanism thevva'lve is usually vactuated by a rocker arm vto open the valve, the rocker Aarm being actuated by suitable mechanism, such as a push rod, which in turn is operated by 4a cam. Springs are provided and operate on the valve stem to close the valve, return the rocker arm `and push rod to their` initial or inoperative positions, and maintain the push rod operating means in contact vwith the cam. In case the valve freezes or sticks and does not close, the valve spring action on the rocker arm, push rod and tappet is suspended and the cam which operates the tappet-hammers the tappet, causing serious damage.

Internal combustion engines and particularly aircraft engines are operated at very high speeds and this has resulted in putting a great strain on the valve mechanism and particularly on the spring closing means. When the engine races at high speed the inertia forces of the rocker arm, push rod and tappet overpower the valve spring and the tappet does not follow the cam, again causing a hammering action to take place. As

usually operated, this spring closing mechanismv is relied on to overcome the inertia of the rocker arm and push rod as well as to close the valve.

This invention has for its salient object to balance the reciprocating and oscillating inertia forces of the rocker arm and push rod, thereby relieving the valve spring from performing this function.

Another object of the invention is to provide a method of balancing valve mechanism so arranged that the only work done by the valve spring is to close the valve, thereby permitting the use of a lighter valve and a lighter valve spring.

Anothercbject of the invention is to provide an independent and self-sucient rocker @rm retracting means whereby the rocker arm, push rod and tappet will operate entirely independently of the operation of the valve.

Another object of the invention is to provide a method of balancing andretracting therocker arm and rocker arm operating mechanism in such a manner that the load on the rocker arm bearing is substantially neutralized.

Further objects of the invention will appear from the following specication taken in connection with the drawing which form a part of this application, and in which 1 Claim. (Cl. 123-90) Fig. 1 is an elevational yview showing the valve and valve mounting in section and illustrating the valve operating mechanism in elevation, this mechanism being constructedin accordance with the invention; and

Fig. 2 is a top plan view, partly in section, of apart of the structure shown in Fig. 1.

In the particular embodiment of the structure for carrying out'the invention there is shown a portion `lil of a cylinder head having a valve guide ii in which is mounted a reciprocatable valve having a stem l2 and a head I3 which seats on a valve seat lll.

A spring l5 surrounds the valve stem and engages a xed Seat I6 at one end thereof and at its opposite end engages the upper end l1 of the valve stern I2.

The valve is actuated by a rocker arm which is mounted on a pin 20 mounted in suitable bearings and the rocker arm comprises an arm 2| having a roller 22 which engages the upper end I1 of the valve stem and a rearwardly extending arm 23 having a pivot socket 24 for receiving the spherical upper end 25 of a push rod 26.

The rocker has a hub 30 which is mounted on a pair of sleeves 3i and 32, the inner sleeve being mounted on the pinv 2G which in turn is mounted in flanged bushings or bearings 33 and 34.

The lower end of the push rod 26 is pivoted at 35 to a cylindrical block 36 which is mounted in a bearing 3'! and has mounted on its lower endl a roller 38 engaging a cam 39. As the cam 3S is rotated the roller and block 35 are reciprocated, thus actuating the push rod 28 and rocker operated thereby.

In the usual or common valve mechanism, a plurality of springs surround the valve stem and operate through the anged head I1 and valve stem to return the rocker and push rod to inoperative position after the valve has been opened and closed. Obviously, with high speed engines in which the valve is operated very fast, this puts an enormous strain on the valve stem and valve spring and has necessitated the use of heavier valves and heavier springs. Even withthese changes breakdowns have been frequent. Moreover, as explained above, at excessively high speeds the inertia forces or load on the rocker arm, push rod and tappet overpower the valve spring and the tappet does not follow the cam. Also, when the valve freezes the rocker operation by the valve spring is suspended.

In order to overcome this condition in the present invention, the rocker, push rod and push rod operating connection are moved to their retracted position or inoperative position by a at coiled spring 49 having a loop 4| which engages the rearwardly extending arm 23 of the rocker and is coiled around the rocker hub 30, the free ends of this spring, shown at 42, engaging a fixed abutment 43 in the cylinder head. It should be noted that the spring 40 puts no load on the bearings of the pin 20 but largely neutralizes the load thereon. The flat coils of the spring 43 which extend around the hub 30 on opposite sides of the rocker function as resilient thrust bearings and maintain the hub and rocker centered between the flanges of the bushings or bearings 33 and 34. The rocker bearing is lubricated and the oil also lubricates the contacting surfaces of the coils. This centering and thrust action is particularly important when the push rod block 35 is not disposed in the plane of the socket 2f and the push rod 26 is not disposed in the plane of the longitudinal axis of the rocker arm 2l.

The spring 4D takes the entire load of the rocker arm or rocker, push rod and push rod operating means and relieves the Valve spring I5 from carrying this load, the sole function of the valve springl being to close the valve. Thus the rocker Will operate entirely independently of the valve and the tappet will always contact and follow the cam. This obviously permits the use of a lighter valve and of a lighter valve spring. The inertia forces on the rocker and push rod are balanced by the spring 4i! which as stated maintains the roller 38 in engagementl with the cam 39.

By reason of the method above described the engine can be operated at much higher speeds without danger of breakdown.

Although one specific embodiment of the invention has been particularly shown and described, it will be understood that the invention is capable of modification and that changes may be made without departing from the spirit or scope of the invention, as expressed in the following claim.

What Iv claim is:

In valve mechanism, a valve guide, a valve having a valve stem reciprocatable in said guide, a cylinder head having spaced bearings therein, a rocker having a pivot pin mounted in said bearings and having an arm engaging the valve for opening the valve, a spring for closing the valve, and a coil spring encircling the rocker pin and engaging the end of the rocker remote from the arm engaging the valve for substantially neutralizing the inertia load of the rocker arm and returning the rocker to its inactive position during the closing of the valve, said coil spring having at coils on opposite sides of the rocker and between the rocker and said spaced bearings to take up thrust coaxial with the rocker pivot axis and center the rocker between said spaced bearings.

WILHELM B. BRONANDER, JR.

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