US3011360A - Ujnuuli maim - Google Patents

Description

Dec. 5, 1961 J. KREISSIG 3,011,360

LEVER ASSEMBLY Filed April 1, i959 INVENTOQ United States Patent 3,011,360 LEVER ASSEMBLY Johannes Kreissig, Stuttgart-Botnang, Germany, assignor to Firma Robert Bosch G.m.b.H., Stuttgart, Germany Filed Apr. 1, 1959, Ser. No. 803,410 Claims priority, application Germany Apr. 2, 1958 6 Claims. (Cl. 74-519) The present invention relates to levers.

More particularly, the present invention relates to levers which are provided with tubular bearings sleeves such as, for example, the interrupter lever of the ignition system of an internal combustion engine.

Bearing sleevesof this type are generally made of a suitable resin. The resin, which may be synthetic, is in the form of an elongated tube from which short lengths are cut so that the individual bearing sleeves may be formed from these short tubular lengths. Each of these short tubular lengths is pressed at their ends into eyes of the lever and then the interior of the plastic tube is finished so as to be provided with the desired diameter.

With the lever assemblies of the above type, there are disadvantages both from the standpoint of the material from which the bearing sleeves are made as well as from the standpoint of the several different steps required in the manufacture of the assembly, such as the cutting of .a short length from the tube of plastic, the pressing of the short length of tube into the eyes of the lever, and then the finishing of the interior diameter of the tube, all of which renders the assembly relatively expensive and requires a considerable amount of time to manufacture.

One of the objects of the present invention is to overcome the above drawbacks by providing a lever assembly of the above type which can be manufactured in a fraction of the time required for conventional lever assemblies of the above type and which is far less expensive than conventional lever assemblies of the above type.

Another object of the present invention is to provide a lever assembly of the above type which is exceedingly strong.

Also, it is an object of the present invention to provide a lever assembly of the above type which will effectively resist any tendency of the bearing sleeve to-become undesirably distorted as a result of relatively large changes in temperature.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a view partly in section of a lever assembly according to the present invention, as seen from the underside of FIG. 2; and

FIG. 2 is a side elevational view of a lever assembly constructed according to the present invention.

Referring now to the drawing, an interrupter lever of an ignition system of an internal combustion engine is illustrated therein incorporating'the structure of the invention and manufactured according'to the process of the present invention. The lever illustrated in FIGS. 1 and 2 includes a pair of side walls and 11 which Patented Dec. 5, 1961 Y are integrally connected at their left end, as viewed in FIGS. 1 and 2, by abridge portion 12 which extends between the side walls 10 and 11, the lever being made of any suitable sheet metal or the like. The bridge portion 12 carries the interrupter contact 13. Furthermore, the side walls 10 and. 11 have a pair of tongues 14 and 15 integrally extending therefrom, and these tongues also extend between the side walls 10 and 11, as shown in the drawing. The tongues 14 and 15 overlap and engage each other and they are interconnected in any suitable way as by a rivet so that these interconnected tongues 14 and 1S serve to increase the stiffness of the lever assembly.

At the end of the lever distant from the bridge portion 12 thereof, the side walls 10 and 11 are provided with eyes 16 and17,.respectively, these eyes being formed by stamping the sheet metal in such a way as to provide the walls 10 and 11 with the tubular portions which form the eyes 16 and 17 as shown most clearly in FIG. 1. It will be noted that the tubular portions at the right end of the walls 10 and 11 extend from these walls toward each other.

In accordance with the present invention a plastic sleeve 18 made of thermoplastic material is injection molded in the space between as well as around the eyes 16 and 17 so as to form the bearing sleeve 18 which has the construction shown in the drawing. The plastic material used for this purpose may be a polyamide such as nylon or polycaprylactam and these plastic materials have the property of becoming plastic only at temperatures above 100 C. These temperatures are only important, because ignition distributors with the described lever assemblies may heat up in service up to 100 C., and therefore the sleeves 18 must also endure these temperatures. When the plastic material hardens in the mold so as to form the sleeve 18, this plastic material shrinks onto the eyes 16 and 17, and furthermore the sleeve 18 forms flanges 19 and 20 at the exterior surfaces of the walls 10 and 11, respectively, so that the sleeve 18 is similar to a hollow rivet which interconnects the side walls 10 and 11. In this way the bearing sleeve provides the lever assembly with an increased stiffness, as compared to bearing sleeves which are pressed into the eyes after being cut from a length of tubing.

The bearing sleeve 18 is formed with the desired inner diameter directly as a part of the injection molding thereof. In order to compensate for tendency of the sleeve to change its shape as a result of temperature changes, which might occur when the temperature changes are relatively large, the sleeve is formed in its interior in the example illustrated with five axial grooves 21 distributed about the axis of the sleeve as shown, the grooves being formed by the mold.

When exposed to heat thermoplastic materials expand more than thermosetting materials. Nevertheless the arrangement of the grooves 21 in the sleeve 18 allows closer tolerances for the bore of the sleeves, because the material may expand into the grooves 21 when the heat increases.

With regard to the manufacture of the sleeves the present invention is not limited to the group of the polyamides, the melting temperature of which lies between 3 or polycarbamates with melting temperatures of 220 C. to 260 C. (Makrolon).

Other materials, such as polyakrylates (Plexigum 8N), polyethylenes (I-Iostalen CG6400) especially perfluorinated polyethylene (Teflon) and trifluoro-rnnochloro polyethylene (Kel-F), and isotactic and syndiotactic polystyrenes (Polystyren 51) are also suitable for the purposes of the present invention.

In all cases the exact quantity of the material, for instance granulated polycaprylactam, is introduced into a press cylinder with a press ram, heated preferably by electricity to 253 C. Attention must be paid to the fact that a temperature higher than the melting temperature may lower the quality of the materials, and a lower one however may make it hard to inject the material.

With a pressure of 400 kg./cm. the liquified material is then injected through a nozzle into a multiple injection mold containing the interrupter levers and perfectly closed on all sides until the mold is filled completely.

The press ram stays at its lower dead center for about 2 seconds in order to avoid back flowing of the polycaprylactam from the mold. Only at the .end of this time the press ram is moved back in the press cylinder, the injection cylinder is lifted off, refilled and prepared for the following cycle.

The mold itself, consisting of several parts, stays closed for 6 to seconds after the injection cycle. When using several molds the still closed mold may cool off outside of the injection press, at the same time the next mold, which has already been prepared for the injection cycle, is inserted into the press.

With this working method a new injection cycle may be started every 7 to 10 seconds. This quick sequence of working cycles is possible on account of the use of thermoplastic materials, which cool fast and do not need a long setting time as thermosetting materials.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of lever assemblies differing from the types described above.

' While the invention has been illustrated and described as embodied in interrupter levers for ignition systems, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of the prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims,

What is claimed as new and desired to be secured by Letters Patent is:

l. A lever assembly comprising, in combination, a pair of spaced side walls formed respectively at one end thereof with a pair of apertures aligned with each other along an axis; and an elongated sleeve of thermoplastic material extending between said side walls and through said apertures coaxial with the latter and being formed with a pair of transverse flanges engaging said side walls, respectively, said sleeve forming the only connection between said side walls at said one end thereof.

2. A lever assembly comprising, in combination, a pair of spaced side walls formed respectively at one end thereof with a pair of apertures aligned with each other along an axis substantially normal to a plane of symmetry between said side walls; a pair of annular flanges respectively integral with said side walls and respectively located about and substantially coaxial with said apertures, said flanges projecting respectively in opposite directions from said side walls and having free ends spaced from each other; and an elongated sleeve of thermoplastic material extending between said side walls and through said apertures and flanges coaxial with the latter and being formed with a pair of transverse flanges engaging said side walls, respectively, on the faces thereof opposite the faces from which said annular flanges respectively project, said sleeve forming the only connection between said side walls at said one end thereof.

3. A lever assembly comprising, in combination, a pair of spaced side walls formed respectively at one end thereof with a pair of apertures aligned with each other along an axis substantially normal to a plane of symmetry between said side walls; a pair of annular flanges respectively integral with said side walls and respectively located about and substantially coaxial with said apertures, said flanges projecting respectively in opposite directions from the inner faces of said side walls towards each other and having free ends spaced from each other; and an elongated sleeve of thermoplastic material extending between said side walls and through said apertures and flanges coaxial with the latter, said sleeve having a large diameter portion between said free ends of said annular flanges so as to engage said ends and having a pair of transverse flanges respectively engaging the outer faces of said side walls, said sleeve forming the only connection between said side walls at said one end thereof.

4. A lever assembly comprising, in combination, a pair of spaced side walls integrally connected at one end thereof by a bridging portion and respectively formed at the other end thereof with a pair of apertures aligned with each other along an axis substantially normal to a plane of symmetry between said side walls; a pair of annular flanges respectively integral with said side walls and respectively located about and substantially coaxial with said apertures, said flanges projecting respectively in opposite directions from the inner faces of said side walls towards each other and having free ends spaced from each other; and an elongated sleeve of thermoplastic material extending between said side walls and through said apertures and flanges coaxial with the latter, said sleeve having a large diameter portion between said free ends of said annular flanges so as to engage said ends and having a pair of transverse flanges respectively engaging the outer faces of said side walls, said sleeve forming the only connection between said side walls at said other end thereof.

5. A lever assembly comprising,in combination, a pair of spaced side walls integrally connected at one end thereof by a bridging portion and respectively formed at the other end thereof with a pair of apertures aligned with each other along an axissubstantially normal to a plane of symmetry between said side walls; a pair of annular flanges respectively integral with said side walls and respectively located about and substantially coaxial with said apertures, said flanges projecting respectively in opposite directions from the inner faces ofsaid side walls towards each other and having free ends spaced from each other, said side walls, bridging portions and annular flanges being formed from sheet metal; and an elongated sleeve of thermoplastic material extending .between said side walls and through said apertures and flanges coaxial with the latter, said sleeve having a large diameter portion between said free ends of said annular flanges so as to engage said ends and having a pair of transverse flanges respectively engaging the outer faces of said side walls, said sleeve forming the only connection between said side walls at said other end thereof.

6. A lever assembly comprising, in combination, a pair of spaced side walls formed respectively at one end thereof with a pair of apertures aligned with each other along an axis substantially normal to a plane of symmetry between said side walls; and an elongated sleeve of thermoplastic material extending between said side walls and through said apertures coaxial with the latter and being formed with a pair of transverse flanges engaging said side walls, respectively, said sleeve forming the only connection between said side walls at said one end thereof, said sleeve 5 being formed at the inner surface thereof with at least two axial grooves uniformly spaced from each other in circumferential direction.

2,035,621 Smith Mar. 31, 1936 Oberdick et a1 Mar. 6 ,1934' Leake Nov. 7, 1950 Thornburg et a1. Dec. 18, 1951 Miller July 7, 1953 Kaugman Aug. 17, 1954 Renholts Jan. 31, 1956 Connolly Nov. 26, 1957 Jacoby Apr. 22, 1958 Muller Dec. 23, 1958 Zankl Nov. 17, 1959

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