US 2733619 A
Description (OCR text may contain errors)
Feb. 7, 1956 R. F. SMITH CAM AND FOLLOWER MECHANISM Filed Aug. 11, 1952 UU u JNVENTOR. RUSSELL F. SMITH ATTORNEY United States Patent Delaware a I Application August 11,1952, Serial No. 303,789 '4 Claims. can-'56s .This invention relates to eccentric and follower mechanis'ms,'and particularlytofthe type embodying a pivoted shoe between the eccentric and the follower lever.
Conventional fuel pumps of the type used on automotive vehicles are commonly actuated by a lever which' has one end resiliently urged into contact with an eccentric on the engine camshaft. In mechanisms in general use the actuating lever has a flat surface which makes a line contact with the face of the eccentric at the point of tangency. Because of the small bearing surface of the lever, the bearing load is highly concentrated and the constant use-to which mechanisms of this type are put, result in severe wear on the lever, so that the service life of the lever is relatively short. A mechanism designed to avoid the elfects of highly concentrated bearing loads embodying a pivoted shoe with an arcuate contact face is disclosed in an application, Serial No. 236,408,
filed July 12, 1951, in the name of James L. Edelen, now
Patent No. 2,654,266., It has been found, however, that in his design excessive wear on the journal portion of the pivot pin substantially reduces the life of pivoted shoes therein disclosed.
It is an object of the present invention to provide a novel pivotal mounting for an arcuate follower shoe whereby wear on the pivot may be minimized.
The above object is achieved by providing the pump lever with a transverse cylindrical depression to receive a cylindrical projection on an arcuate cam follower'shoe.
A projecting lip or other means on one edge of the depositions of the shoe.
Fig. 3 is a perspective view of the shoe.
The automotive fuel pump illustrated in Fig. l is of the well-known Carter type now in wide use and includes a body portion 5, which contains an operating diaphragm, valves, and'vapor' dome spaces, all as disclosed in a copending application Serial No. 728,979,'filed February 17, 1947, in the name of Irven'E. Coffey, now Patent No.
2,625,114. Secured to the upper 'part of body 5 is a right angle lever housing 6 into which projects diaphragm stem 7 through flexible seal 8. Diaphragm spring 9 constantly urges the diaphragm in thedischarge direction, that is, downward. An operating lever 10 of channel cross section is pivoted at 11 to the walls of the lever housing and has a bifurcated end 12 which underlies an abutment washer 13 at the end of stem 7.
According to the present invention, the outer end of lever 10 is provided with a transverse substantially semi- ICC cylindrical recess 15 hits upper surface. The purpose of recess 15 is to pivotally receive a cylindrical projection 17 of arcuate cam follower shoe 18. Shoe 18 is provided with an arcuate contact. face 20 of equal radius with eccentric cam 21 mounted on camshaft 22. The lower surface of the contact shoe proper is connected to cylindrical projection 17 by a short neck portion 23 substantially less in cross-section than the diameter of cylindrical projection 17. Projection 17 is retained in a recess .15. provided with a half-round socket by a deformable upwardlyextendinglip portion 25 formed on the outer axial edgeof recess 15 and extendingbeyond a diametral plane ofthe halfround socket in the" recess.
Lip 25. isbendable to permit easy insertion and removal of the arcuate shoe and to secure fthe shoe to theleven;
afinalss eq sa a s ar w ps at s ithflt s. a jacentedge of neck 23 to prevent extreme movements of the follower shoe. This is especially useful in instal lation of the pump, since it eliminates the necessity of manually guiding the follower shoe into engagement with the cam upon installation of the pump. This latter would obviously be necessary if the follower shoe were not restrained in somewhat near its normal operating range of positions. To prevent lateral movement of the shoe in and out of the recess, flanges 29 are formed on both sides of the shoe and engage the side portions of the lever adjacent theends of recess 15. Shoe 18 is constantly urged into engagement with cam 21 by means of a coiled spring 26- compressed between the undersurface of the lever and a seat 27 formed in the open mouth of lever housing 6.
It is evident from Fig. 2 that the very slight angular movement of cylindrical projection 17, combined with the relatively large contact surface between the cylindrical projection and the semi-cylindrical recess 15, will result in minimizing the wear on these contact surfaces. The advantage of thelarge arcuate contact surface 20 of the shoe is similarly evident. moves between its right-hand, dead center, and lefthand positions, the shoe merely follows it, wear on the bearing surfaces between the shoe and lever being minimized as described above.
This invention is not limited in its applicability to automotive fuel pumps of the type illustrated and described herein, but is equally adaptable to automotive vacuum booster pumps and other devices embodying eccentric and follower mechanisms.
It will be understood that the form described and illustrated herein is but the preferred embodiment of my invention and that exclusive use is contemplated of all modifications coming within the scope of the appended claims as will occur to those skilled in the art.
1. In an eccentric and follower mechanism, a follower element comprising a lever and a shoe, said shoe having an arcuate contact face and an axially aligned cylindrical projection from its undersurface, a relatively slender neck portion joining said shoe and said projection, said lever being formed with a recess providing a semi-cylindrical socket to pivotally receive said cylindrical projection, and a lip projecting from an axial edge of said recess for securing said projection in said recess, said lip and the adjacent edge of said 'neck'portion co-acting to limit pivotal movement of said shoe.
2. In a cam and pivoted lever mechanism, a shoe comprising axially spaced concave and convex bearing members adapted to ride on said cam and lever respectively, said shoe including means extending between said hearing members for connectingsaid members in spaced relation, said connecting means comprising laterally extending flanges integral with the ends of said concave and convex bearing members.
Patented Feb. 7, 1956 In operation, as the cam 3. In a cam and pivoted lever mechanism, a shoe comprising axially spaced concave and convex bearing-members adapted to ride on said cam and lever, respectively,
said shoe including a necked portion between said bearing ineinb eis for canfieafifig said bearing fiiein spaced relation; a'iid oppositely a gee flanges iii r with the 'eiids of s'aid 'co" D bearing member and said n'eck'ed portion, and extending to said concave searing 4 deformable lip providing an extension of said recess, and spaced, dependent flanges cooperating with said recess and said convex bearing member to retain said shoe in said socket.
References Cited in the file of this patent UNITED STATES PATENTS 2,404g231 Harper 161? -16,- 1946 2,415,623 Brooks Feb; 1947 2,497,322 'Rathbun Feb. 14, 1950 2,508,551 Wood May 22}, 1950 2,654,266 Edelen Oct. 6, 1953 V FOREIGN PATENTS 432,504 France Oct. 6, 1911 505,24; great Britain "J y 19, 1,948 "614,387 Ffaiicef Dec. 13, 1926