US2302325A

US2302325A - Engine starter gearing

Info

Publication number: US2302325A
Application number: US421065A
Authority: US
Inventors: Clinton S Janes
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1941-11-29
Filing date: 1941-11-29
Publication date: 1942-11-17
Anticipated expiration: 1959-11-17

Description

C. S. JANES ENGINE STARTER GEARING Nov. 17, 19 12.

Filed Nov. 29, 1941 Patented Nov. 17, 1942 ENGINE STARTER GEARING Clinton S. Janes, Elmira Heights, N. Y., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application November 29, 1941, Serial No. 421,065

9 Claims.

The present invention relates to engine starter gearing and more particularly to a device for assuring engagement of a starter drive pinion with an engine gear when the starting motor is energized.

In starter gearing of the type in which a drive pinion has a threaded connection to the starting motor for automatic traversal into and out of operative position, detents are sometimes used for resisting rotationof the pinion in order to assure its traversal. In the application of Elkin, Serial No. 392,724, filed May 9, 1941, such a detent is disclosed which is arranged to momentarily engage or jab against the pinion simul taneously with the energization of the starting motor. In installations of this kind, if the engine should fire a few times and then die, the operator may reclose the starting switch while the starting motor is still spinning from the previous starting operation, and if the pinion detent is then operated, the pinion will be jammed against the engine gear which may cause milling of the gear and pinion teeth.

It is an object of the present invention to provide a novel engine starter gear having a meshenforcing detent for the pinion, in which reactuation of the detent is prevented during rotation of the starting motor.

It is another object to provide such a device incorporating a relay which is controlled by the current generated by the armature of the starting motor while it spins by momentum in its residual field to prevent actuation of the detent until the starting motor comes substantially to rest.

It is another object to provide such a device incorporating a time delay which comes into operation after the release of said relay, to further delay actuation of the detent until after the starting motor has come completely to rest.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing in which:

Fig. 1 is a semi-diagrammatic illustration oi an engine starting system incorporating a preferred embodiment of the invention, and

Fig, 2 is a similar view of a somewhat simpliiied form of said invention.

In Fig. 1 of the drawing there is illustrated a a starting system including a motor I having an extended armature shaft 2 on which is threaded a pinion 3 for longitudinal movement into and out of engagement with an engine gear 4. Means for energizing the starting motor is provided including a battery 5 grounded at 6 and connected by a lead I to a magnetic starting switch 8. Switch 8 is connected by lead 9 to the starting motor which latter is grounded at H to complete the starting circuit. Starting switch 5 is arranged to be actuated by an electro-magnet i2, and a control circuit for said electro-magnet is shown' comprising a lead I3, a manually operable push button i4, lead l5 and ground connection l6.

According to the present invention a mag netically operated detent I1 is provided for resisting initial rotation of the pinion 3 in order to assure its traversal into engagement with the engine gear 4 when the starting motor I is energized, Detent I1 is normally maintained out of engagement with the pinion 3 by means of a spring I8, and an electro-magnet. I9 is provided for moving the detent into operative position. A control circuit for the electro-magnet I9 is shown comprising a lead 2| connected to the push button [4, a lead 22, fixed contact 23, and contact 24 mounted on a vibrator reed 25 which is anchored and grounded at 26.

The free end of the reed 25 is provided with a bob 2'! which is adapted to be engaged by an arm 28 pivotally mounted at 29 in position to bend the reed 25 back so as to separate contact 24 from contact 23 when the arm is swung downwardly. Means for actuating the arm 28 is provided in the form of a magnetic plunger 3i and a solenoid 32 acting thereon, which solenoid is connected at one end by a lead 33 to the starting motor lead 9 and is grounded at its other end as indicated at 34.

In the operation of this embodiment of the invention, closure of the push button I 4 causes simultaneous energization of the coil l2 of the magnetic starting switch 8, and the actuating coil IQ for the detent IT. The detent I1 is thus caused to engage the pinion 3 at the same time that the starting switch 8 closes, so that the detent is in operative position before the starting motor begins to rotate. Closure of the starting switch 8 also completes the circuit through the solenoid 32 of the vibrator relay, but since the starting motor, when at rest has a very low electrical reactance, the energization of the solenoid 32 is delayed slightly due to the fact that its inductance is much greater than that of the motor, and at this time the solenoid is in parallel with the motor. After a very brief time interval, the motor starts to rotate, and its reactance thus increases. The solenoid 32 is then effective to actuate the plunger 3i to draw down the arm 28 and cause

contacts

23, 24 to open, thus deenergizing the detent coil i9 and permitting the spring l8 to move the detent to idle position The time interval consumed by this operation, however, is sufficient to ensure that the starting motor has rotated sufficiently to cause the pinion 3 to enter into mesh with the engine gear 4 so that the detent has served its function.

During the cranking operation,

contacts

23, 24, are held open by the solenoid 32. When the engine starts, release of the push button l4 by the operator permits the parts to return to the normal or idle position. If, however, the engine should fail to continue self-operative, the operator may again close the push button I4 in order to re-actuate the starting system. If the operator does not allow sumcient time for the starting motor to come to rest, the pinion would not ordinarily be traversed into engagement with the engine gear, since the acceleration of the starting motor would be insufficient to secure the traversal of the pinion. If, however, the detent ll were actuated at such time, the pinion would be forcibly jammed against the engine gear with consequent milling of the engaging teeth and/or shock loads caused by the collision of the rapidly rotating armature and its associated parts against the stationary teeth of the engine gear, In order to avoid this undesired actuation of the pinion detent, the current which is generated by the armature of the starting motor i as it spins in its residual field is utilized to hold the

contacts

23, 24 open. As shown, this is accomplished by so connecting the solenoid 32 as to place it in series with the motor when the starting circuit to the battery is broken by the opening of the starting switch 8. The arm 28 is thus held down by the current generated by the motor until the armature comes substantially to rest, When the relay arm 28 is thus released, the reed 25 is set in vibration by the flicking action of the end of the arm on the bob 21, whereby an additional time delay is secured before the

contacts

23, 24 remain closed so as to permit actuation of the detent coil l9. This additional time delay is so predetermined as to permit the starting motor to come completely to rest before it becomes possible to reactuate the detent H.

In some types of engine starters, particularly of the heavy duty and double gear reduction types, it may be found desirable to increase the length of time during which the detent is held against the pinion in order to give plenty of time for a slow-moving pinion to get into mesh with its engine gear. This may readily be accomplished by slowing down the action of the vibrator relay as by means of a suitable short-circuited coil 30 encircling the plunger 3i and thus delaying the action of the relay,

In the embodiment of the invention illustrated in Fig. 2, the starting circuit is controlled directly by a manual switch 35, which switch is provided with an additional set of contacts 36 arranged to close the magnetic detent circuit prior to closure of the starting circuit. The remaining structure is substantially the same as illustrated in Fig. 1, the parts being similarly numbered, except that the control of the starting operation is performed directly by the operator instead of by the magnetic starting switch and push button control.

Although but two embodiments have been shown and described in detail, it will be understood that other embodiments are possible, and changes may be made in the design and arrangement of the parts without departing from the spirit of the invention as defined in the claims appended hereto.

What is claimed is:

1. In an engine starter a starting motor, a

pinion, screw means actuated by the starting motor for moving the pinion into mesh with an engine gear, a detent for resisting rotation of the pinion, means for actuating the detent and means responsive to rotation of the starting motor preventing actuation of the detent.

2. In an engine starter a starting motor, a pinion, screw means actuated by the starting motor for moving the pinion into mesh with an engine gear, a detent for resisting rotation of the pinion, electro-magnetic means for actuating the detent, and means energized by current generated by the armature of the starting motor while spinning in its residual field, for preventing actuation of the detent.

3. An engine starter as set forth in claim 1 including, further, means for delaying the actuation of the detent a predetermined time after the starting motor comes substantially to rest.

4. An engine starter as set forth in claim 2 including, further, means for delaying actuation of the detent a predetermined time after the startin motorcurrent falls to a value so low as to be ineffective to prevent actuation of the detent.

5. In an engine starter a motor, a pinion, screw-threaded means operable by the motor to move the pinion into mesh with an engine gear, a detent for resisting rotation of the pinion, means energized prior to the energization of the motor for actuating the detent and means energized concurrently with the energization of the motor for releasing the detent.

6. In an engine starter a motor, a pinion, screw-threaded means operable by the motor to move the pinion into mesh with an engine gear, a detent for resisting rotation of the pinion, electro-magnetic means energized prior to the energization of the motor for actuating the detent and a slow-acting relay energized concurrently with'the energization of the motor for releasing the detent.

'7. An engine starter as set forth in claim 5 including, further, means responsive to rotation of the starting motor for preventing reactuation of the detent.

8. An engine starter as set forth in claim 5, including, further, means responsive to rotation of the starting motor for preventing reactuation of the detent, said means incorporating provisions to prevent actuation of the detent until a predetermined time after the motor comes substantially to rest.

9. An engine starter as set forth in claim 6, said relay being energized by current generated by the starting motor spinning in its residual field, to prevent release of the relay until the starting motor comes substantially to rest.

CLINTON S. JANES.