US1371940A - Timer - Google Patents

Description

A. E. SMITH.

TIMER.

APPLICATION FILED SEPT. 12, 1919.

Patented Mar. 15, 1921.

FIG. 2

lNVE/V TOP? ATTOPN E Y W/TNESSES UNITED STATES PATENT OFFICE.

ALBERT E. SMITH, OF MILWAUKEE, WISCONSIN, ASSIGNOR, BY DIRECT AND MESNE ASSIGNMENTS, TO MILWAUKEE AUTO ENGINE AND SUPPLY COMPANY, OF MIL- WAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

TIMER.

Specification of Letters Patent.

Patented Mar. 15, 1921.

To all whom it may concern:

Be it known that I, ALBERT E SMITH, a citizen of the United States, and resident of Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented new and useful Improvements in Timers, of which the following is a description, reference being had to the accompanying drawings, which are a part of this specification.

The invention relates to timers or distributers for internal combustion engines for making and breaking the ignition'circuits to the ignition devices of the engine.

In the usual construction of timer, a movable brush cooperates with the contacts of the commutator which contacts have a straight joint with the insulating material of the commutator so that the brush travels all on the contact or all on the insulating material. In practice the contacts of this type of commutator start pitting near the jointafter a short time and this pitting gradually wears a groove into the contact near its break end which causes an uneven action of the brush as it travels over the contact and limits the period of eflicient operation of the timer, so that the commutator has to be frequently renewed. The present invention is designed to overcome this difficulty by providing a commutator in which each of the contacts set into the insulating material has a break end of such a character as to permit the brush to ride both on the insulating material and on the contact during the breaking. By this construction I have found that the pitting at the break end of the contact gradually works back as far as the main body portion of said contact while the insulating material adjacent this break end Wears down, and by the time the pitting has reached the body portion of the contact, then the previous pitted surface of the contact and the insulation have been worn down so as to bring the whole portion of the break end again into active operation. Furthermore, in this gradual wearing down process the brush or roller will be carried over any pitted portion of the break end by the insulating material upon which it rides.

The fact that the brush rides partly on the break end of the contact and partly on the fiber at the time of breaking the circuit, prevents an uneven action of the brush even though the end of the contact be pitted, and the extended or narrowed break end of the contact saves the main body portion of the contact from pitting and'causes a smooth action of the roller on the track formed by the commutator.

The invention further consists in the several features hereinafter set forth and more particularly defined by claims at the conclusion hereof.

In the drawings: F ignre 1 is a sectional view through the timer showing the device embodying the invention; Fig. 2 is a detail vertical sectional view through the commutator embodying the invention.

The commutator 3 is mounted in a casing & and is in the form of a ring of insulatmg material 5 having contacts 6 inset therein and forming therewith a continuous circular trackway 7 upon which runs a brush 8. This brush is here shown in the form of a roller but it may be a sliding shoe or any other suitable form of contact moved over the track 7 to successively engage the contacts of the commutator. As here shown the roller 8 is carried by a lever 9 pivotally mounted intermediate its ends upon an arm 10 secured to the timing shaft 11, said lever being moved by a spring 12 to hold the roller against the track, all of which brush construction is well known. The invention resides in the contact and its arrangement with reference to the insulating material of the commutator. The break end 13 of each contact where it oins with the insulating material of the trackway is narrower than the width of the main body portion of the contact and preferably gradually decreases in width from an imaginary line 14 to its end 15, thus forming an angular extension from the main body portion of the contact. However, I desire it to be understood that this narrowed break end of the contact may be of different forms than the one specifically shown so long as the brush when leaving the main body portion of the contact rides partly on the contact and on the insulating material during the breaking.

I'Vith the construction herein shown I have pitted end has worn down to such an extent that the roller again rides both on this end and the fiber and all parts wear down together and then the action of pitting from the end 15 to the line 14 is again repeated after a certain period. Thus, even though pitting occurs at the break end of the contact, the efficient action of the timer isnot impeded and the commutator contacts can be used fora much longer period of time than those in the usual form of timer.

In the drawings I have shown the joint between'the .contact 6 and the insulating material at the make end 16 as being straight because at this end there is no sparking and consequently no liability for pitting, but if such a condition should occur the make end of the contact may also have a portion projected out from the main body of the contact so that the brush rides partly on the insulating material and "partly on the make end of the contact for a brief period.

It is to be understood that this invention is not limited to any specific form or arrangement of parts, except in so far as said limitations are specified in the claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a timer, the combination, with a contact roller, of a commutator cooperating therewith comprising insulating material and spaced contacts inset therein to form a track for the roller, each of said contacts at its break end being of less width than the main body ortion of the contact so that the brush during breaking 'rides partly on the contact and partly upon the insulating material.

2. In a timer, the combination of a commutator comprising an insulating member and spaced contacts inset therein to form a track therewith, a contact roller running on said track, each. of said contacts at its break end having a projection from the that the roller during breaking rides partly on the contact and partly upontthe insulating material.

In testimony whereof, I afiix my signature;

ALBERT E. SMITH.

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