US2322172A

US2322172A - Valve actuating mechanism

Info

Publication number: US2322172A
Application number: US411232A
Authority: US
Inventors: Louis R Spencer
Original assignee: SPENCER AIRCRAFT MOTORS Inc
Current assignee: SPENCER AIRCRAFT MOTORS Inc
Priority date: 1941-09-17
Filing date: 1941-09-17
Publication date: 1943-06-15
Anticipated expiration: 1960-06-15

Description

June 15, 1943. R. SPENCER 2,322,172

VALVE ACTUATING MECHANISM Filed Sept. 1 1941 2 Eheets-Shet 2 Patented June 15, 1943 UNiTED STATE VALVE ACTUATING MECHANISM Application September 17, 1941, Serial No. 411,232

Claims.

This invention relates to improvements in valve actuating mechanisms, and particularly that type of valve actuating mechanism wherein a rocker arm is rocked by an operating cam for the purpose of imparting motion to a valve stem, as illustrated in United States Letters Patent Nos. 2,209,480 and 2,226,985.

One object of the present invention is to pro-' vide means for minimizing wear on the operating cam and that portion of the surface of the rocker arm which is contacted or engaged by said cam.

In Patent No. 2,209,480, means are illustrated for forcing a supply of lubricant to the contacting surfaces of the rocker arm and its operating cam, but the structure illustrated in that patent is such that, if there should be a momentary stoppage in the flow of lubricant, those surfaces might become excessively hot and impaired by such heat, due to the fact that the parts normally operate at comparatively high surface speeds. A further object of the present invention, therefore, is to provide means for retaining a reserve supply of lubricant in the rocker arm for these contacting areas of the rocker arm and the cam.

More specifically, the invention contemplates the provision of a lubricant reservoir orlubricant-retaining recess in the rocker arm, to which reservoir or recess the lubricant is fed through a passage in the arm and in which recess there is a revolving member against which the cam engages, the lower peripheral portion of said member being submerged in the lubricant retained in the recess, whereby the wiping action of the cam causes the member to revolve and constantly advance a lubricated portion of the periphery of said member into cam-engaging position.

A still further object is to provide a comparatively simple means for insuring correct assembly of the rocker arm in the valve actuating mechanism. Furthermore, as explained in Patent No. 2,226,985, diniculties have been encountered in maintaining a flat contact between the surface of the rocker arm and the rocker arm cam, and a still further object of the present invention is to provide means for permitting the rocker arm to adjust itself to the surface of the cam, said means being so constructed as to not require the use of any small structural elements that might be difficult to assemble or which might be easily broken.

With these and other objects in view, the invention consists in certain details of construction and combinations and arrangements 0f parts, all as will hereinafter be more fully described and the novel features thereof particularly pointed out in the appended claims.

In the accompanying drawings- Figure 1 is a sectional View taken longitudinally of the rocker arm, illustrating one form of the present invention;

Fig. 2 is a similar view showing the rocker arm depressed.

Fig. 3 is a plan view, partly in section, of the structure shown in Figs. 1 and 2;

Fig. 4 is a view similar to Fig. 1, illustrating a modified form of the invention;

Fig. 5 is a plan View of the rocker arm of Fig. 4;

Fig. 6 is a sectional view on the line 6-6 of Fig. 4;

Fig. 7 is a sectional view taken on the line l| of Fig. l; and

Fig. 8 is an exterior, elevational view of a portion of the motor casing, illustrating the bearing therein for the rocker arm mounting.

As illustrated in Fig. 1, the rocker arm i0 is pivotally supported in. the wall of the motor casmg I I, with its free end in engagement with the valve stem 12, so that, as the arm is depressed by its operating cam 13, the valve stem will be correspondingly depressed. As will be understood, when the high portion of the cam I3 rides away from its engagement with the rocker arm, the valve stem [2 will be returned upwardly by suitable spring devices (not shown). As more fully illustrated and described in Patent No. 2,209,489, lubricant is fed through a passage M in the rocker arm to a cavity in which the valve stem engaging disc l5 is seated, and from this cavity lubricant is distributed through a branch duct It to the contacting surfaces of the disc l5 and valve stei I2. In said Patent No. 2,209,480, the valve stem engaging disc I5 is also provided with a second branch duct, indicated at ll in the present instance, for supplying lubricant to the surface of the rocker arm against which the operating, cam engages. However, the construction in Patent No. 2,209,480 is such that, if there should be a stoppage of any material duration in the feed of lubricant through the rocker arm, the contacting surfaces of the rocker arm and operating cam would heat up to raise the temperature of those surfaces to a point where the surface-hardening at those portions would be seriously impaired. This difficulty is overcome in the present instance by providing the rocker arm with a lubricant reservoir or lubricant-retaining recess in which there is a revoluble cam-engaging member so positioned that its lower peripheral portion will always be submerged in lubricant, whereby, under the influence of the cam tending to turn said revoluble member, a freshly lubricated portion of that member will be constantly advanced into position to be engaged by the operating cam. In the embodiment of the present invention illustrated in Fig. 1, the lubricant reservoir or lubricant-retaining recess is indicated at 3, and lubricant is supplied to this recess from branch duct I! in the valve stem engaging member, through a duct IS) in the rocker arm which communicates with a short section of tubing 20, which projects from the rocker arm into the lubricant reservoir or recess i8. J ournaled to revolve in said recess is a roller 2| against which the cam l3 engages. The roller 2| may be journaled on a cross pin 22 mounted in the side walls of the lubricant-retaining recess IS. AS will appear from an inspection of Figs. 1 and 2, depression of the rocker arm Ii! causes the duct H in valve stem engaging member to move into registry with duct 19, under which circumstances a small quantity of lubricant will be forced through those ducts, and through tube from which it will be discharged into the lubricant reservoir or cavity H3. The lubricant will accumulate in this cavity so that the lower portion of roller 2| will be submerged in the lubricant and, as the wiping action of the cam l3 causes the roller to revolve, freshly lubricated portions of the roller will be constantly brought into position to be engaged by the operating cam. The capacity of this lubricant reservoir or recess I8 is such that, if there should be any appreciable stoppage in the feeding of the lubricant through the several lubricant passages, the accumulated lubricant in the cavity I8 will be sufiicient to maintain proper lubrication of the contacting surfaces of the roller 2| and cam 13 for an appreciable length of time.

In the embodiment of the invention illustrated in Figs. 4 to 6, the cam-engaging member takes the form of a disc 2| in lieu of a roller. The disc is loose in the cavity, being retained therein by reason of the fact that the cavity walls embrace more than one-half of the circumference of the disc, and by the use of a detachable side plate 23, secured to one side of the rocker arm by suitable fastening means. of the disc has to make a comparatively close fit with the surface of th lubricant reservoir or recess, it is preferred that What might be termed the bottom of that recess be formed with a groove 24, so as to insure lubricant in the re- I cess having access to a comparatively larg area of the periphery of the disc. Also, the closeness in the fit of the disc in the lubricant reservoir or recess renders the use of an overhanging tube, such as 20 in Fig. 1, impossible, so that, in this modified form of the invention, the lubricant is conveyed from the duct in the valve stem actuating member l5 to the recess by a passage 20 in the rocker arm, this passage 2!] preferably being so located as to be in registry with the groove 24 in the bottom of the lubricant reservoir.

In Patent No. 2,226,985, the rocker arm is pivoted in a cylindrical member which is adapted to rock in its bearing in the motor casing wall, so that the arm may accommodate itself or adjust itself to maintain a flat contact with the surface of its operating cam, and this rocking motion of the member in which the rocker arm is carried is limited by a ,pin in the casing wall loosely engaging in a recess in said cylin- As the periphery drical member. Such a construction presents some difficulty in assembly, and the use of the pin for limiting the rocking motion of the cylindrical member in which the rocker arm is carried presents a rather fragile structural element. In the present instance, the use of comparatively small arts, such as the pin referred to in the previously mentioned patent, is eliminated, and a substantial structure that may readily be assembled is provided by having the rocker arm pivotally carried in a member or mounting formed of two different diameters at different portions of its length, with these two portions of different diameters arranged eccentrically of one another, the bore in the casing wall being correspondingly formed to receive the member of this shape. For instance, as shown in Figs. 1, 7 and 8, the member in which the rocker arm is pivoted is formed for the major portion of its length with a cylindrical surface 25 concentric with the axis on which the rocker arm is adapted to tilt to accommodate itself to the surface of its operating cam. Near its inner end, this mounting for the rocker arm is formed of a reduced diameter 26 arranged eccentrically of the portion of larger diameter 25. Similarly, the bore in the motor casing wall is formed with a portion of larger diameter, indicated at 27, corresponding to the portion 25 of the rocker arm mounting member, and with an inner portion 28 of lesser diameter corresponding to the formation of the reduced portion 26 of the rocker arm mounting member. Due to the eccentricity of the smaller portion of the bore 28 with respect to the larger portion 21 thereof, and the corresponding eccentricity of the two portions of different diameters of the rocker arm mounting member, the mounting member can be inserted in the bore in the casing wall in one position only. Furthermore, the diameters of the reduced portion 23 of the bore in the casing wall and of the reduced portion 26 of the rocker arm mounting member are such that there is sufiicient clearance between these two associated parts as to permit the rocking member to turn or rock slightly in its hearing. In other words, the portions of larger diameter of the bore in the casing wall and of the rocker arm mounting member being arranged concentrically of the axis on which the rocker arm is to be permitted to tilt, turning of said mounting member and tilting of the said rocker arm is limited only by the closeness of the fit between the smaller portion 25 of the mounting member and the smaller portion 28 of the bore in the casing wall. It will be appreciated that the fit between the portions of larger diameter of the rocker arm mounting member and the bore in the casing wall should be such that there will be no material play or looseness of the mounting member in its bearing. The rocker arm bearing member is yieldingly held in its bearing by a spring plate 29 carried on the cap 30 which serves as a covering for said member, this cap being secured to the casing wall by suitable fastening means 3|.

What I claim is:

1. In a valve actuating mechanism, a rocker arm having a lubricant retaining recess in the upper surface thereof with a groove in the bottom surface of said recess. and a disc loose in said recess free to roll on the grooved surface of the recess, said disc being adapted to be engaged by the actuating cam of said arm.

2. In a valve actuating mechanism, a rocker arm having a lubricant retaining recess in the upper surface thereof, a disc loose in said recess adapted to be engaged by the actuating cam of said arm, said disc being free to be revolved by th wiping action of said cam, and a, lubricant passage in said arm for supplying lubricant to said recess.

3. In a valve actuating mechanism, a rocker arm having a valve stem engaging member therein and a lubricant supply duct therein communicating with the stem engaging surface of said member, said arm also having a recess therein located to one side of said duct and a branch passage extending from said duct to said recess, and a rotatable bearing member in said recess adapted to be engaged by a cam, said recess being closed to retain lubricant therein to a level above the lower peripheral portion of said bearing member.

4. In a valve actuating mechanism, a rocker arm having a recess in the upper surface thereof,

a valve stem engaging member in the bottom face thereof with a lubricant supply duct extending through said arm and communicating with said recess and with the stem engaging surface of said member, and a roller journaled in said recess adapted to be engaged by the actuating cam of said arm.

5. In a valve actuating mechanism, a rocker arm having a recess in the upper surface thereof, said recess being open at one side of said arm, a disc loose in said recess, and a retaining member spanning the open side of said recess to prevent lateral escape of said disc, said arm having a lubricant passage therein communicating with said recess and said recess having a groove in its bottom surface for distribution of lubricant to the periphery of the disc.

LOUIS R. SPENCER.