US2621539A - Cam construction for use in timers - Google Patents

Description

16, 1 2 l. N. EUSTIS ETAL 2,621,539

CAM CONSTRUCTION FOR USE IN TIMERS Filed May 51, 1950 2 Sl-IEETS-SHEET l Dec. 16, 1952 N. EU-STIS EI'AL 2,521,539

CAM CQNSTRUCTION FOR USE IN T-IMERS Filed May 51, 1950 I .2 SHEETS-SHEET 2 Patented Dec. 16, 1952 CAM CONSTRUCTION FOR USE IN TIMERS Irving N. Eustis and Neil J. McDonald, Fairmont, Minn assignors to Fairmont Railway Motors, Inc., Fairmont, Minn., a corporation of Minnesota Application May 31, 1950, Serial No. 165,292

3 Claims. 1

The invention is more particularly concerned with cam constructions for use in timers of the type which include a resilient blade-like memher that carries a contact point and which memher is actuated so that its contact point has a make and break engagement with a stationary part forming a part of the timer construction.

Timers of the type mentioned are used extensively in connection with internal combustion engines which furnish the power for railway motor cars of which inspection and section cars are specific examples. Certain typical engines used for this purpose comprise a construction in which the timer is positioned between the fly Wheel and the crank case and parts of the timer are, for weather protection, positioned within a housing, making access to the cam or actuator impossible without first removing the fly wheel. Again, the engines are generally so mounted in the cars that the fly wheel cannot be removed without first removing the engine from the car. The cam or actuator member wears in time to the point where the timer does not have a sumcient arc of contact and when this occurs it is necessary to renew the timer cam or actuator.

In prior constructions, to insert a new cam, it has been necessary to remove the flywheel, and, in cases where the engine is mounted in the car, the engine must first be removed from the car to permit removal of the fiy wheel. Such construction make cam renewal laborious and expensive.

The general object of the present invention is to provide a cam timer of such construction that when wear of the part which actuates the resilient blade-like element has progressed to the point requiring renewal, such renewal can be made quickly and easily.

A further object of the invention is to provide a cam timer in which renewal of a worn part can be made without removal of the fly wheel and also if the engine be in position in a car, without requiring removal of the engine from the car.

Another object of the invention is to provide a cam timer structure wherein a portion in the nature of a cam lobe, which is associated with the cam body, may be removably held in place in the cam body without the use of screws, pins or the like and in such manner that such portion can be quickly removed from the cam body and a new part replaced by means of a simple tool and without removing the cam body from the shaft on which it is mounted.

Again it is an object of the invention to provide 2 a method of assembling a cam lobe part With the body of the cam, which method may be practiced without the use of special tools and by persons of ordinary skill.

Other objects of the invention, as well as the advantages thereof, will more fully appear as the specification proceeds.

In the drawings:

Fig. 1 is a top plan View of the end of a crank shaft bearing portion of an engine showing the timer in position thereon and with a cover portion of the timer removed better to disclose the timer cam.

Fig. 2 is a vertical sectional view taken 0 the line 22 of Fig. l but with the timer cover and parts carried thereby in position on the timer housing.

Fig. 3 is a perspective view of the cam lobe member alone, on an enlarged scale relative to the scale of Figs. 1 and 2.

Fig. 4 is an end view of the cam sleeve body and cam, substantially on the scale of Fig. 3, and

Figs. 5 and 6 are views illustrating the method of assembling the cam lobe and cam body or sleeve.

Fig. 7 is a detail view illustrating a part of a further method of assembling the cam lobe and cam body or sleeve.

Referring now in detail to that embodiment of the invention illustrated in the drawings and with reference particularly to Figs. 1 and 2, ll] indicates a part of the crank case of an internal combustion engine of the type frequently used as the motive power for a railway motor car. Connected thereto by bolts H is a bearing collar l2. An extension collar 1 3 is secured at its inner end to the collar 12 and is provided at its outer end with an annular flange-like enlargement l4.

l5 indicates a part of the engine crank shaft which projects through the bearing and extension collars. Fixed to the outer end of the shaft [5 is a fly wheel 56 held in place by a conventional nut IT.

IS and 19 indicate respectively the upper and lower parts of the timer structure which encircle the collar extension I 3, being clamped in place by means of bolts 23. The upper part It of the bracket is formed to provide an open top housing or chamber 2 i. The housing is of elongated rectangular shape and is arranged in a plane transversely of the axis of the crank shaft l5. Said chamber is defined at its sides and ends by upright walls 22 and 23. On each end wall is a pair of laterally spaced ears 2d for a cross pin 25. The bottom end of a spring arm 26 is pivoted oneach cross pin, the top end terminating in an ogee catch 21.

The open top end of the chamber 2| is closable by a block-like cover element 28 releasably held in operative position by means of said spring arms 26-26.

The closure element 28 is provided at one end with a flat bottomed boss 29 and at its other end with a shouldered boss 33. A pair of vibratile blades 31 are clamped at one end to the boss 23,

the other end of one of the blades resting at times upon the upwardly facing shoulder of boss 30. Fixed to the upper face of said last mentioned blade is a contact 32 for a make and break engagement with the bottom of contact 33. A helical expansion spring 34 imposes a yielding downward pressure on the blades 3i.

35 indicates a condenser unit which is mounted on the cover member 28, the function of which is conventional.

It will be noted from Fig. 2 that there is an opening 36 in the upper part of collar 13. A cam body or sleeve 31 is keyed to the cam shaft IS in line with this opening and carries a cam lobe 38. In the rotation of the cam shaft the cam lobe 38 will engage the lower blade of the blades 3| and cause contact 32 to engage contact 33 momentarily to Obtain the necessary make and break engagement.

In the course of operation the lobe portion will eventually wear to such an extent as to require replacement. Heretofore in timer constructions of this general type it has been necessary to remove the fly wheel in order to remove the cam. As before explained, engines of the type embodying timers of the construction heretofore designed are frequently installed in railway motor cars in such a way that in order to removethe fly wheel it is first necessary to remove the engine from the car. The present invention obviates the necessity of removing the engine or fly wheel and enables replacement quickly and easily.

The construction of the cam body or sleeve, the cam lobe and the method of assembly will be best understood by reference to Figs. 3 to 6 inclusive. In the outer face of the cam body or sleeve 31 are longitudinal grooves 43-40 which are undercut to provide the overhanging lip portions 4l--4l. Between the lip portions 41-4! is an abutment portion 42 which serves to support the center part of the cam lobe part 38 when the parts are assembled, as appears in Fig. 4.

The cam lobe part 38 is generally of an arcuate form transversely considered and along each side it terminates in wedge shaped edges 43-43. Paralleling the edges 43-42 are V-shaped grooves 44-44, the purpose of which will shortly appear.

The cam lobe part 38 may be made of various materials but it should be a material which will be sufficiently resilient so that the edges 4343 can be brought together by pressure of the magnitude which can be exerted by a hand tool in the nature of a pair of pliers or tongs. At the same time, the material should be tough, have good wearing qualities and also be a non-conductor of electricity. By making the cam lobe of a material which is a non-conductor of electricity it is possible to make the body sieeve 3'. of metal so that the cam lobe can be brought closer to the center of the crank shaft which is desirable from an operative standpoint. We have discovered that nylon embodies the several desirable characteristics. While a solid mass of nylon could be machined, it is possible to mold the'nylon and thus facilitate and reduce the cost of manufacture. Obviously, other materials having the neoessary characteristics may be used, but the prefered material is nylon.

By reference merely to Figs. 3 to 6 inclusive, it might be assumed that the cam lobe 38 could be inserted from one end of the grooves 40-40. By reference to Fig. 2, however, it will be observed that when the parts are in their operative position in the timer as assembled in the engine it is only possible to move the lobe 38 radially relative to the cam sleeve 3'1, because the same must be passed. through the narrow top opening of the part l8. As before explained, it would not be possible to remove the sleeve 1 3 without removing the fly wheel l6, which it is one purpose of the invention to avoid.

By reference to Fig. 5 it will be observed that the distance D between the lips 4I4| is less than the distance Dr between the tips of the portions 4343 when the lobe 38 is in its unstressed condition. In order to insert the lobe member 38 into the sleeve it is gripped as shown in Fig. 6 by the tong-like ends or jaws 5050 of the plier-like tool 51 and pressure applied to reduce the distance Dr to D-, thus permitting the lobe to be moved radially to the desired position. Upon release of the pressure the cam lobe springs back to its unstressed condition, thus locking the cam lobe 38 firmly in place as shown in Fig. 4. To remove the cam lobe it is only necessary to reverse the operation. The cam dimension, in a direction longitudinally of the crank shaft, is less than that of the width of the open top of the casing part i8. Hence, it is possible to insert the plier 5! through the open top of the casing to permit removal of a worn cam lobe and replacement of a new lobe when required. Of course it will be understood the cover member 23 will first be removed, but this requires but an instant as it is only necessary to swing the spring clips 26 away from their locking position to permit such removal.

In Fig. 7 is illustrated a part of another way in which the lobe 38 may be applied to the cam body and this is by inserting one edge 43 of the lobe, while the latter is in its unstressed condition under its associated lip 4| on the cam body, the remainder of the lobe then being engaged in supporting relation upon the part 42 of the cam bod-y and other lip 41 respectively. In this position it is to be noted that both grooves 44 of the lobe are fully exposed in a position to be engaged by the jaws 5B of the plier-like tool to further arch or bow the lobe to permit the other edge 43 thereof to pass its associated lip H to enter its associated groove 48. When the tool is removed from the lobe, the latter will expand laterally to secure itself inoperative position relative to the cam body or sleeve.

The many advantages of the invention will be understood by persons skilled in the art to which the invention relates. However, While describing the invention we have referred to the form, arrangement, construction of the parts and the method of assembly, the same is to be considered in an illustrative sense, so that we do not wish to be limited thereto, except as may be specifically set forth in the appended claims.

We claim as our invention:

1. An engine timer construction embodying therein an annular cam body, means providing laterally spaced shoulders longitudinally of the body, and a cam lobe member having side portions sprung toward each other and engaged at their edges with a holding pressure against said shoulders, said lobe member having a longitudinal central contact portion and said side portions including shoulders outside the periphery of the cam body for engagement by a tool for springing said side portions transversely of the lobe member toward each other.

2. An engine timer construction embodying therein an annular cam body, means providing laterally spaced parallel shoulders longitudinally of the body, and a transversely cam lobe memher having side portions sprung toward each other and engaged at their edges with a laterally outward holding pressure against said shoulders, said lobe member having a longitudinal central contact portion and said side portions each having a longitudinal groove therein outside the periphery of the cam body and providing shoulders for engagement by a tool for springing said side portions transversely of the lobe member toward each other.

3. An engine timer construction embodying therein a cam body provided with laterally spaced longitudinal parallel grooves, the outer side of each groove being undercut to form a lip overhanging a part of the associated groove, a transversely sprung cam lobe member having a- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 329,904 Humphrey Nov. 10, 1885 855,773 Hanson June 4, 1907 1,701,522 Zimitz Feb. 12, 1929 1,780,856 Adam Nov. 4, 1930 1,803,326 Gernandt May 5, 1931 1,815,134 Weiner et a1. July 21, 1931 2,163,864 Bissell June 22, 1939 2,569,096 Geiger et a1. Sept. 25, 1951

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