US1964729A - Starting mechanism - Google Patents

Description

July 3, 1934.

STARTING MECHANISM Filed Oct. 15, 1931 Am 4m Sep/z/a/ze Graig biz Patented July 3, 1934 UNITED STATES ATENT OFFICE.

Application October 15,

1931, Serial No. 569,094

In France October 15, 1930 8 Claims.

This invention relates to mechanisms for effecting the starting of any rotating element and more particularly to such mechanisms for starting internal combustion engines.

The present invention has to do with starting mechanisms operating on the general principle of the well-known Bendix drive and the device forming the subject-matter of this application employs the broad principle of that drive but 10 presents new features and advantages not heretofore realized.

The principal object of the present invention is to provide a starter drive which presents novel means for causing the engagement between the starter pinion and the engine fly-wheel.

Another object of the present invention is to provide novel means for cushioning the engagement between the starter pinion and the flywheelcarried gear.

A further object of the present invention is to provide a starter drive of extremely simple and light construction, and which will be very inexpensive to manufacture or repair.

Other objects and features of novelty will be apparent from the following detailed description when taken in connection with the accompanying drawing. It is to be expressly understood however, that the drawing is for purposes of illustration only and is not designed as a definition of the limits of the invention, reference being had for this purpose to the appended claims.

The single figure of the drawing illustrates one form of the invention and is to be taken as an illustration of only one embodiment thereof and not in any way as limiting the scope of the invention.

In the single figure of the drawing, the letter or represents the usual armature shaft of a starting motor, which armature shaft is, in usual manner, rotated by the starting motor when it is desired to start the engine of the vehicle on which the present device may be mounted. Formed integrally with the armature shaft is an abutment or enlargement d, although it is to be understood that any other means for attaching or forming an abutment on the armature shaft may be used.

A spring b is coiled about the armature shaft (1, and at one end is attached thereto by any suitable means, a bolt 0, about which one end of the spring is coiled, being illustrated as such attaching means in the drawing. At its other end the spring b abuts against the abutment d but is in no way attached thereto. The coils of the spring 5 b may have any desired pitch and any desired cross-section, it being necessary only that both the pitch and cross-section are constant throughout. In the drawing the spring has been shown with a rectangular cross-section which is the preferable form, although not requisite.

Also coiled about the armature shaft :1 is a second helical spring e, the coils of which are intermeshed with the coils of the spring 17. The two springs are so arranged that the coils of the spring e fit exactly into the spaces between the coils of the spring b. At one end the spring e abuts directly against the abutment d but is in no way attached thereto. At its other end the spring e is deformed to provide a spur j which is directly in thepath of the pinion, when the same moves along the armature shaft. The spring e is of such length that the spur J is located at a relatively small distance from the end of spring b and from bolt 0, there being a small number of convolutions of spring b be tween spur f and bolt 0, for a purpose which will be explained hereinafter. The spring e is formed with the same pitch as spring 15) but with a smaller cross-section. As illustrated in the drawing, spring e is formed with rectangular cross-section, having the same width as spring I) but shorter in a radialdirection. Both springs are wound snugly on the armature shaft a.

Mounted on the armature shaft a and springs b and e is a pinion g which is designed to engage and transmit rotation to the flywheel-carried ring gear h when it is desired to start the engine. This pinion is formed with internal screw-threads which have a pitch equal to the width of the convolutions of spring b. The construction is such that the pinion threads, spring I) and spring e all fit snugly.

It will be apparent from the above description that pinion g may be moved along armature shaft a by screwing it along the helical spring I), and that any rotation of pinion y will cause such longitudinal movement and that, conversely, rotation of armature shaft or and therefore springs b and e will effect longitudinal movement of pinion y if the same is held from rotation.

In its inoperative position, pinion g is in a retracted position resting against the spur f. In order to provide the necessary inertia of pinion 9 it may be weighted in the usual manner. Assuming the pinion to be in inoperative position against spur if it is desired to start the engine the armature shaft a is caused to rotate by means of the starting motor. The inertia of the pinion g preventing its rotation with shaft a it is moved longitudinally of the shaft by means of the screw-thread engagement between the helical spring 12 and the internal screw-threads of the pinion g. When the pinion reaches the abutment cl it will be stopped thereby and will thereafter rotate with shaft a. As at this time it is in mesh with the ring gear h, rotation of the flywheel and starting of the motor will result. With the motor started, the speed of rotation of the flywheel will be greater than that of the armature shaft and pinion and the pinion will be moved out of engagement with the flywheel and will once more rest against the spur f.

In the event that, on an attempt being made to start the engine, the pinion teeth abut the;

teeth of ring-gear h, the continued and very slight rotation of armature shaft (1 will cause the internal screw-threads of pinion g to exert a thrust on the convolutions of spring b which will; tend to compress those free convolutions of spring b which lie between spur f and bolt 0. Such compression of spring b will relieve the pressure of the pinion g against ring-gear h; and allow the armature shaft to rotate the pinion into a, position wherein the teeth thereof can mesh freely with the teeth of the ring-gear.

In this last described operation the peculiar emcacy of the spring e becomes apparent. If this spring were not in its position, the abutment of the pinion teeth against the teeth of the ringgear would cause compression of spring 1) throughout its length and a consequent lessen.- ing of the pitch of said spring I). This would immediately cause the convolutions of spring I) to tighten on the internal screw threads of the pinion, causing jamming and consequent distortion of the spring b. With the use of spring e as described, the pitch of spring I), where it engages with the pinion, is always constant, and the necessary compression of the spring takes place freely at a place where it cannot be adversely affected;

While there has been shown and described one embodiment of the invention, it is to be understood that the invention is not limited thereto. Various other changes and modifications in the shapes, sizes and manner of assembling the various component. parts may be resorted to without departing from the scope of the invention, as will occur to those skilled in the art. Reference will therefore be had to the appended claims for a definition of the limits of the invention.

1. In a starter drive comprising an armature shaft and a pinion, flexible means for causing longitudinal movement of the pinion along the shaft and rotation therewith, and means for preventing the jamming of said flexible means when the longitudinal movement of the pinion is obstructed.

2. In a starter drive comprising an armature shaft and a screw-threaded pinion, a helical spring on which said pinion is threaded, and means independent of the threads of said pinion for maintaining the pitch of said helical spring constant throughout a portion of the length thereof.

3. In a starter drive comprising an armature shaft and a screw-threaded pinion, a helical spring on which said pinion is threaded, means independent of the threads of said pinion for maintaining a portion of said helical spring substantially rigid, the other portion of said spring remaining flexible.

4. Ina starter drive, an armature shaft, a helical spring coiled thereabout and attached thereto, a second spring coiled about said shaft and intermeshed with, said first-named spring, a pinion mounted on said shaft, said second spring having a portion limiting the movement of said pinion along said shaft.

5 In a starter drive, a power shaft, a threaded driving member mounted thereon, a yieldingspiral, member mounted on said shaft and fixed at one end thereto, and arranged to cooperate with the threads of the driving member for traversing and driving the same, and means for rigidly spacing the convolutions of the spiral member adjacent the driving position of the driving member.

6. In a starter drive, an armature shaft, an abutment on said shaft, a helical spring surrounding said shaft and attached thereto at one end, a, second spring surrounding said shaft and intermeshed with the first named spring for a portion of the length of said first named spring, the second named. spring being deformed at its end to provide an abutment, and a, pinionthreaded on said first named spring.

7. In a starter drive, an armature shaft, a spring surrounding said shaft, a pinion threaded on said spring, a, second spring coiled about said shaft, said second. spring having a lesser crosssectional area, than-the first spring.

8,, In a starter drive, an armature shaft, a spring surrounding said. shaft, a pinion threaded on said spring, a second spring coiled about said shaft, said, second spring having a shorter length than said first named spring,

STEPHANIE} GRANJON.

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