US2481248A - Engine starting apparatus - Google Patents

Description

p 1949- P. L. SCHNEIDER ET AL 2,481,248

ENGINE STARTING APPARATUS Filed May 20. 1948 2 Sheets-Sheet 1 .mwmns WZMW 6, 1949.. P. L. SCHNEIDER ET AL 2,431,248

ENGINE START ING APPARATUS Filed May 20, 1948 2 Sheets-Sheet 2 Patented Sept. 6, 1949 UNITED STATES PAT OFFICE 2381,2448 ENGINE, STARTING. APPARATUS Application May 20, 1948., SerialNo. 28,197

Claims.

This invention relates to-enginestarting apparatus of the type inwhich the operation ,of the electric motor causes a pinion driven thereby to be moved axially into mesh with theflywheei'gear of the engineto bestarted and in whichthepinion is automatically derneshed from the gear when the engine becomes self-operative and tends to drive the pinion faster than it can be driven by the engine starting motor.

An object of the present invention is taprovide an engine starter drive'of the type referred to which effects the meshing of the pinion with the engine gear although the pinionteeth may abut the ends of the gear teeth; In order to accomplish this object, the disclosed embodiment of the present invention includes a spring through which motion is transmitted axially to'thepinion so that, in the event of abutment of the pinion teeth with the flywheel gear teeth, the pinion teeth can slip onthe gear teeth while the pinion is being rotated bythe motor intomeshing registration with the gear.

Further objects and advantages of" the present invention will be apparent from the followingdescription, reference beinghad to the; accompanying drawings whereina preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a longitudinal sectional view'of a portion of the housing and electric starting motor "supported thereby together with a side elevation partlyin longitudinal section of anengine starter drive embodying the present: invention.

Fig. 2 is a side view-of the engine starterdrive looking in the direction ofarrow [of Fig. 1'.

Figs. 4 and 5 are sectional views taken, respectively, on lines 3-3, 4-4 and 55of Fig, 1.

Fig. 6 is a side view of part. 'I'l shown in Fig. 2 at the left end ofthe starter drive;

Fig. '7 is a view in the direction of arrow 1 of Fig. 6. 1

Fig. 8 is partly a fragmentarx-view in the direction of arrow B of 'Figgl tand partly a sectional' view on line 8 -'8of Fig. 7.

Fig. 9 is a view in the direction of arrow 9: of Fig. 8 the part in section being. taken. on line 9--9 of Fig. 8.

Fig. 10 is a View partly in the direction. .fiarrow ID of Fig. 9 and partly a sectional. view, on, line ill-Ill of: Fig. 9.

Fig. 11 is a view of part 5'! shown in F gifi.

Fig: 12 is a view in the direction ofarrow'i'Z of Fig. 11.

Fig. 13 is a sectional view on the-1ine:-l3j-.-l,.3' of Fig. 12.

2 Fig. 14 is asectional' view on the line 14-44 of Fig. 4, showing parts 8!: and 83.

Fig. 15- is an end view of a spring 61. Figs. 16 and 17 are views taken, respectively, 5 inthe direction of arrows i6 and 11' of Fig. 15.

Fig. 1815 a side view'partlyin section of part 41.

Fig. 19 is a sectional view on line I9-l*9; of Fig. 18.

Figs. 20 and: 21 are views in the direction of arrows ZOand 21 respectively, of Fig. 19.

Referring to Fig. 1', a housing adapted to be attached to the housing (not shown) oian engine flywheel gear I06 supports a motor field frame 3|. whose left end, not shown, supports a bearing for anarmature shaft 32 journallcd also ina bearing 33 providedbyframe 30. The shaft 32: supports an armature 34. rotating between field pole pieces 35 surrounded by field coils (not shown).

The engine starter drive comprises a screw 41 shown in detail in Figs. 18'-21'. Screw 4i cornprises a sleeve 42 provided externally with triple thread helical splines 43. Sleeve 42' provides a wide flange 4:42 having holes 55 diametrically opposite for receiving a pin (Fig. 1 passing diametricallythrough the shaft 32. The flange 12 1 has a groove.

The screw 41' receives a. nut 5| provided internally. with triple thread helical splines 53: adapted 30 to cooperate with the helical splines 43 of the screw 41. Nut 51. provides a hole 52 (Fig. 2)

forreceiving-end portion 62' of a spring SI which,

as shown in Fig. 1', is. located between the nut 5.1: and the screw-flange 44 and has an end portion .6;3 received. in the groove l? of said flange saidportion 6.3ihaving: right anglebendiii l extend ing across the left rac of the flange 44. Nut 51 liassa stop; mg adapted: to engage with a stop lug H of a ring H- which fits aroundthe flange ofthescrew 4|" and has holes '12 for receiving the ends of pin 46,. said pin being retained by' a split wire; snapring 73 received by groove 15in the; ring T11}, .To retain the snap ring is, it is provided with an inwardly extending portion 13a 45 (Fig. 2)- receivedby-a hole 16 in ring H (Figs. 8

and 9)... Nut 51" provides stepped cylindrical: surfaces 55. and: 51 and a plane annular surface 58 and an annular groove 59';

The assembly (Fig. 14). comprises a ring 8| having notches 82 for receiving the teeth of the pinion I00.- Ring; N is brazed to. a sleeve 83 having an internal flange 84- and an internal cylindrical surface 85 which is adapted to fit closely around the surfacev 55 of nut 51;. Sleeve 55- 83-has acylindricalnsurface: Biiof; the same; diameter as surface 56 of nut and the cylindrical surface 8! of the same diameter as the surface 57 of nut 5|. As shown in Fig. 1, the sleeve 83 and the nut 5| are surrounded by a clutch spring 80 having its end turns ground to provide plane surfaces perpendicular to the axis of the spring adapted to contact plane surface 58 of part 5| and plane surface 88 of part 8| respectively. Spring 9|] is confined between surfaces 58 and 88, the distance between these surfaces with registers 55 and 85 in engagement being slightly greater than the overall length of spring 98 and the parts are retained by a tubular case 92 surrounding the spring 98 and the ring 8|, the-right end of the sleeve 82 being shaped at 8| to conform to the rounded edge of the ring 8| and i the left edge of the case 92 being crimped at 93 into the groove 59 of the nut 5|. Normally the spring 9i? frictionally engages the nut 5| at the surface 5'! and the sleeve 83 at the surface 81.

The pinion |88 has a hub extension |il| which fits within the internal flange 84 of the sleeve 83 and is surrounded by a spring |82 located between the left ends of the pinion teeth and the flange 84. The pinion is retained in assembly by a split wire snap ring I83 which snaps into a groove in the hub extension NH and is engaged by the flange 84.

When the starting motor is connected with a current source, its shaft 32 accelerates rapidly in a clockwise direction as viewed in the direction of arrow 85 (Fig. 1), thereby causing the nut 5! to move toward the right and to move the pinion I80 into engagement with the flywheel gear IEIE. When the pinion I88 is fully meshed, it will have moved into position I88 into engagement with a stop provided by washers and H2 which abut C-washers H3 received by a groove H4 of the shaft 32 and retained by a cupped disc H6 held in place by being staked or rolled into the shoulder of the C-washer H3. The disc H5 abuts a washer ||l abutting a finished surface H8 of the frame tfl. After right motion of the pinion I88 has been stopped, the nut 5| continues to move right until the right end of sleeve 83 engages the left ends 'of the pinion teeth. Since the nut 5| cannot move further to the right the screw 4| and the nut 5| rotate together as a unit. For the moment, the portion of spring 98 engaging surface 81 of sleeve 83 can be considered fixed since the ring 8| connects sleeve 83 with pinion 88. Therefore, since the left end of spring 98 frictionally engages surface 51 of the rotating nut 5|, the spring 98 wraps itself about the surfaces 56 and 86 of the nut 5| and sleeve 83, respectively, thereby effectively transmitting torque from the screw to the pinion and causing the pinion to turn and drive the engine gear I86.

When the engine becomes self-operativa'it tends to drive the pinion I88 faster than it can be driven by the starting motor and the pinion is automatically demeshed and returns to the normal position with the stop lug 54 of the nut 5| abutting the stop lug 14 of the ring TI. Thereturn of the pinion to normal position is assisted by the spring 6|, the turns of which had been deflected axially and torsionally during movement of the pinion into mesh with the flywheel gear.

Motion of the nut 5| is transmitted axially to the pinion through the spring I82. If the ends of the pinion teeth should abut the ends of the gear teeth, spring I82 is deflected as the nut 5| continues moving right and the pressure applied to the gear teeth increases to such value that the clutch spring begins to wind up and wrap itself about the nut 5| and sleeve 83 and a torque is transmitted to the pinion sufficient to cause it to turn into meshing registration with the gear. Then, as the pinion starts turning, the frictionatresistance to turning is slightly reduced because the running friction is slightly less than the static friction. Should the pinion teeth rub against a slight irregularity of the gear teeth, the pinion is free to move left so that it can slide over the irregularity on a gear tooth surface because the pressure applied to the pinion is a yielding pressure. Entrance of the pinion teeth into thespaces between the gear teeth is facilitated by chamfering the gear and pinion teeth as shown in Figs. 1, 2 and 4. When meshing registration is effected, the spring I82 is released -to move the pinion quickly into partial meshing with the gear. Thereafter complete engagement of the pinion with the gear is effected andrelatively high torque is applied through the clutch spring 90 to the pinion to rotate the gear.

The internal diameter of the spring 98 is normally greater than the diameter of surfaces 56 and 86 of parts 5| and 83, respectively, and is lessthanthe diameter of surfaces 5'! and 81 of these parts. Hence, the spring 90 is expanded to fit over surfaces 51 and 81. The so-called interference fit between spring 90 and surfaces 51 and 8'! must be such as to cause the spring to wrap itself about the surfaces 56 and 86, but not so great as to prevent slippage. Some slippage should be present to cushion the shock incidental to starting the cranking operation. The clutch should slip a little to absorb the kinetic energy stored in the rotating motor armature and thus reduce the shock and noise which occur when the pinion engages. For a brief interval after the pinion engages, during which the gear starts moving, an abnormally high torque pro duced by the kinetic energy stored in the rotating armature is applied and the clutch slips. As this kinetic energ is dissipated the torque decreases to the normal torque produced by the starting motor and the clutch slippage decreases to zero under normal cranking conditions. The clutch must be capable of transmitting the full normal torque developed by the starting motor without slipping.

When the drive disengages and stoplugs 54 and 74 meet, considerable kinetic energy is stored in the parts which are rotating with respect to the screw 4|, If this energy were all absorbed instantaneously when the stop lugs meet, undesirably high stresses and some rebound would result. In this design some of the kinetic energy stored in spring 90, tubular case 92, assembly 88, and pinion I88 is dissipated by the slipping ofthe spring clutch 98 when torque in a clockwise direction is applied to it.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. An engine starter comprising an electric motor having a shaft, a screw supported by the shaft and driven thereby, a pinion supported by the shaft for axial movement into mesh with the .gear of an engine to be started; a nut threadedly a spring for transmitting motion from the sleeve to the pinion in a direction to move the pinion toward the gear, a clutch spring having its end turns normally in frictional engagement with the nut and sleeve and which wraps itself about the nut and sleeve in response to a rotative movement of the nut relative to the sleeve in the engine starting direction of rotary movement of the pinion, and an abutment provided by the shaft for engagement by the pinion when fully meshed with the engine gear whereby, after said axial lost motion is taken up, the screw and nut rotate together as a unit.

2. An engine starter according to claim 1 in which the connection between the sleeve and the pinion is provided by a ring attached to the sleeve and having internal longitudinal splines engaging the teeth of the pinion.

3. An engine starter according to claim 1 in which the nut abuts the sleeve whereby motion is transmitted axially in the pinion meshing direction from the nut to the sleeve, and in which motion is transmitted axially in the opposite direction by a tubular case enclosing the clutch spring and retaining the clutch spring, nut and V sleeve in assembly.

4. An engine starter according to claim 1 in which the spring which transmits motion from the sleeve to the pinion surrounds a hub extension of the pinion which extends through an in- V ternal annular flange of the sleeve which flange and screw yieldingly maintains engagement of the stop lugs and assists in disengaging the pinion after tooth demeshing.

PAUL L. SCHNEIDER. HAROLD J. CROMWELL. DENNIS W. NIGHBERT.

No references cited.

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