US2450231A - Engine starter - Google Patents

Description

p 1943. J. E. BUXTON 2,450,231

ENGINE STARTER Original Film ad June 23, 1944 I INVENTOR.

6. Bumlbn WITNESS 3 Patented Sept. 28, 1948 I ENGKNE STARTER James E. Bunion, Elmira, N. Y., asslgnor to Bendix Aviation Corporation, a corporation o8 Delaware Original application .iune 23, 1944, Serial No. 541,702. Divided and thisappiicatlon July 1, 1946, Serial No. 680,791

2 Claims.

The present invention relates to an engine starter, and more particularly to a starting system incorporating gearing of the type in which energization of the starting motor automatically effects engagement of the gearing and such engagement is maintained until the engine. is reliably self-operative, whereupon the acceleration of the engine gear is permitted to disengage the gearing.

This application is a division of the application of Patent No. 2,429,388, issued October 21, i947.

In starter gearing of the above indicated type,

' it is usual to provide an overrunning connection to the starting pinion in order to prevent the engine from driving the armature oi the motor which might causeit to rotate at a dangerously high speed. The use of such clutches, however, has been found in some instances to make the demeshing of the pinion somewhat sluggish and consequently noisy. Moreover, the types of overrunning clutch heretofore used have sometimes been undesirably noisy in operation.

It is an object of the present invention to provide a novel engine starter of the type which maintains its engagement with the engine until continuous self-operation of the engine is secured, incorporating means to insure prompt disengagement of the drive on completion of the starting operation.

It is another object to provide such a device incorporating an overrunnin clutch which forms a reliable and positive driving connection, and overruns freely and quietly.

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

Fig. 1 is a side elevation partly in section or a preferred embodiment of the invention; the electrical circuits involved being shown diagrammatically;

Fig. 2 is a section taken substantially on the line 2-4 of Fig. 1; and

Fig. 3 is a detail in perspective of the latch pin and its actuating member.

In the drawing, there is illustrated a starting system including a battery I grounded at 2 and connected by a lead 3 to a starting switch 4 conveniently located for control by the operator of theengine to be started. Switch 4 is connected by a lead 8 to the field windings B and I of a starting motor 8. At their other ends the fields 6 and 1 are connected to the brushes 8 and II respectively, which conduct current through the armature 02 to the brushes i8 and iii-which are grounded to complete the starting circuit.

Means are provided for connecting the starting motor 8 to rotate a member such as a flywheel gear of the engine to be started. For this purpose, the starting motor is provided with an armature shaft I5 having a smooth reduced extension it, the reduction in diameter being de= fined by a thrust shoulder it against which one or more thrust washers i0 are preferably seated. On the outer end of the extension it there is rigidly mounted a driving head it as by means of a cross pin it retained by a lock ring 25. The driving head it has a smooth cylindrical exten sion 2!, and a screw shaft 22 is slidably jour-= nalled thereon and yieldably connected for rotation therewith by means of a torsion spring 23 anchored at its ends to the driving head and screw shaft by means of anchor plates 26 and 2E. The anchor plates are nonrotatably mounted on the driving head and screw shaft and have slots adapted to receive the outturne'd ends it and 2? of the spring, respectively.

A pinion 28 is slidably iournalled on the extension it of the armature shaft for longitudinal movement into and out of engagement with a member such as a gear 29 of the engine to be started. Means for traversing the pinion into and out of operative position and for rotating the pinion is provided comprising a nut 8E9 threaded on the screw shaft 22 and rigidly connected at one end to a barrel member ii. The opposite end of the barrel is connected to the pinion by means of an overrunning clutch comprising a driving plate 32 anchored as indicated at 33 in the barrel and having clutch teeth it on its face. A driven clutch member 35 is fixed as indicated at 36 on the pinion and has teeth 31 adapted to engage with the teeth 8! of the driving clutch member. Means are provided for limiting the separation of the driving and driven clutch members and for transmitting a light frictional drag from the pinion to the barrel memher. in the form of a thimble 38 anchored to the end of the barrel 3! as indicated at 38 and having a swivel connection with the pinion by means of a thrust ring 48 seated in the interior oi the i'himble in position to engage a shoulder on the driven clutch member 35 so as to limit separation of the clutch members. A spring 4| located between the clutch members is arranged to hold said members normally out of engagement.

According to the present invention, means are provided for maintaining the pinion 28 in engagemeat w th the engine gear 28 until a successful start of the engine has been secured. As here shown, this means comprises a latch pin 42 slidably mounted in the control nut 30, and an actuating member therefor in the form of a ring 43 slidably but non-rotatably mounted on the control nut. ,Pin 42 is provided witha notch 44, adapted to receive a reduced section "of ring 43 so as to couple the pin to the ring for sliding movement in unison. The ring is retained on the barrel by suitable means such as a. lock ring 46.

The inner end of the pin 42 is preferably flattened as indicated at 41, and bears-on the periphery of the screw shaft 22. Means for pressing the pin against the screw'shaft is provided in the form of a plunger 48 slidably mounted in a recess 49 in the nut to opposite the pin 42, and a switch ll and simultaneously energizing the trip solenoid 34 immediately upon opening the starting switch 4. As shown. this means comprises an electromagnet 61 which is connected by leads through the spring 23 to the screw shaft 22, and

the nut 30 is traversed along the screw shaft until the pinion 28 engages the thrust washer l0.

2 Since the longitudinal movement of the pinion is compression spring here shown as a rubber block 50 which presses the plunger 48 against the ring member 43. Screw shaft 22 is provided with a notch 5| in position to receive the end of latch pin 42 when the barrel assembly has moved the.

' time causing rapid deceleration of the starting motor in order to insure that demeshing of the pinion takes place promptly and without interference between the teeth of the pinion and the flywheel gear as the pinion moves out of mesh. In order to accomplish this result, recourse is had to the electrical braking device disclosed in the patent to J anes, Number 2,353,900, issued July 18, 1944, and assigned to the assignee of the present application.

For this purpose, the Junctions of field coils 8 and 1 of the starting motor with brushes 9 and II, respectively, are connected by leads 52, 53 and 54 to an electromagnet 55 which is arranged when actuated to close a switch 56. Switch 56 controls a circuit which is in shunt with the starting switch 4 and comprises a lead- 51 connected to the battery lead 3, a resister 58, a lead 59 and a lead 60 connected to the starting motor lead 5.

The brakingefi'ect of the motor is secured as described in said application by grounding the lead 54 which short-circuits the armature I2 of the starting motor while maintainin the energizatlon of the field coils 6 and I. To this end, a switch Si is connected to the motor lead 54 and by a lead 82 to the ground at 83.

According to the present invention, the how of current through the grounding circuit 52, 53, 54, Si, 62, 63 is used to withdraw the latch 42 from the notch 5|. For'this purpose, a solenoid in the form of a single turn coil-64 is inserted in the ground lead 62 which solenoid is arranged when actuated to project a finger 65 into the path of rotation of the ring 43. Engagement of the finger with the ring as it rotates moves the ring into concentric relation with the axis of the drive, thereby raising the latch out of the notch iii and freeing the barrel and pinion assembly for demeshing movement. The finger 85 is normally held out of engagement with the ring 53 by suitable means such as a spring 66.

Means are provided for closing the grounding thus arrested, it is compelled to rotate with the armature shaft and thereby rotates the engine gear 29 with which it is in mesh. At this time, the latch 42 has entered the notch 5| of the screw shaft under the pressure of the spring so that backward movement of the barrel is limited by engagement of the latch in said notch. When the meshing movement of the pinion is arrested, further movement of the barrel compresses the spring 4| and closes the clutch 32, 35 whereby the pinion is rigidly connected for rotation with the barrel.

During the cranking operation, rotation of the armature 12 of the starting motorcauses the generation of a counter E. M. F, in said armature which voltage is expressed between the brushes 9 and II and the ground. This voltage is impressed upon the electromagnet causing closure of switch 56. Since the starting switch'4 is closed, however, there is no voltage drop across the resister 58, and consequently the grounding switch 6| remains open.

When the engine fires, the pinion 28 is acceler-' the clutch being assured by the light frictional connection between the pinion and barrel provided by the swivel connection 40.

- When the engine has become reliably self-operative, the operator opens the starting switch 4 whereupon the cur-rent through the starting motor is compelled to traverse the shunt circuit including the resister 58 and switch 56. The consequent voltage drop across the resister 58 energizes the electromagnet 81 to close the grounding switch 8| which shortcircuits the armature l2 causing a powerful braking effect to be applied to the starting motor. At the same time, the coil 84 is energized to bring the finger into the path 'of the latch ring 43 thus tripping the latch and permitting the nut 30 with itsassociated parts to be traversed back to idle position by the deceleration of the armature'shaft. As soon as the starting motor comes substantially to rest,'the counter E. M. F. of its armature dies out and the voltage across its brushes is reduced substantially to zero whereupon the electromagnet 55 is deenergized, permitting switch 58 to reopen, thus breaking the starting motor circuit and permitting the grounding switch iii to open and thetrip finger 65 to return to its idle position.

Although but one form of the invention has." been shown and described in detaiL'it will be 1111- r 5 derstood that-other embodiments are possible and that various 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 drive. a power shaft, a screw shaft driven thereby. a nut threaded on the screw shaft, a pinion slidably iournalled on the power shaft for movement into and out of enga8e ment with a gear of an engine to be started. means including a barrel member for transmitting longitudinal movement from the nut to the .pinion, means for arresting the longitudinal movement of the pinion, clutch members connected to the barrel and pinion adapted to be forced into driving engagement by the nut when the meshing movement of the pinion is arrested yielding means normally holding the clutch members disengaged, and means for limiting the separation of the clutch members, said last mentioned means serving also to transmit a frictional drag from the pinion to the barrel member.

2. In an engine starter drive. a power shaft. a screw shaft driven thereby. a nut threaded on the screw shaft. a pinion slidably iournalled on the power shaft for movement into and out of engagement with a gear of an engine to be started. means including a barrel member for transmitting longitudinal movement from the nut to the pinion, means for arresting the longitudinal movement of the pinion, and clutch members connected to the barrel and pinion adapted to be forced into driving engagement by the nut when the meshing movement of the pinion is arrested; yielding means normally holding the clutch members disengaged, and means for limiting the separation of the clutch members. said last mentioned means comprising a thimble non-rotatably connected to one of the clutch members, and a thrust ring forming a swivel and frictional connection to the other clutch member.

JAMES E. BUXTON.

REFERENCES CITED The following references are of record in the file of this patent:

Number Da Great Britain Jan.

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