US2583829A - Wrap spring starter - Google Patents

Description

1952 s. GILBERT 2,583,829

WRAP SPRING STARTER Filed June 5, 1949 IN V EN TOR.

SAMUEL G/LBEPT Patented Jan. 29, 1 952 UNITED STATES PATENT OFFICE I WRAP SPRING STARTER.

Samuel Gilbert, Cedar Grove, N. J., assignor to Bendix Aviation Corporation, Teterboro, N. J a corporation of Delaware Application June 3, 1949, Serial No. 97,030

1 Claim. 1

This invention relates to engine starters, and more particularly to the engaging mechanism employed in starters for internal combustion engines.

In the conventional starter the engaging means usually comprises an engine jaw adapted to mesh with a clutch jaw mounted on a screw shaft. An axially stationary rotatable spline nut is threadably connected to the screw shaft to cause it to move axially and mesh the clutch jaw with the engine jaw. The spline nut is connected to the driving means by a friction disc pack. Usually an overrunning clutch is inserted in the engaging means in order to protect the starter mechanism when the engine speed is above that of the starter. Although the above mechanism gives very accurate control over the clutch setting and can carry the high torques of larger engines, it can be seen that the conventional starter is quite complicated and expensive for use where accuracy and high torque are not required.

It is an object of the present invention to avoid disadvantages of apparatus of the aforesaid character and to do so by novel means.

Another object is to conserve weight and cost over a usual starter structure.

Another object is to provide a simple engaging means which also limits torque.

Another object is to provide a simple engaging means which performs the function of an overrunning clutch.

Another object is to provide engaging means to avoid the requirement of axial movement of the engaging member.

The above and other objects and features of the invention will appear more fully hereinafter from a consideration of the following description taken in connection with the accompanying drawing wherein one embodiment of the invention is illustrated by Way of example.

In the drawing the single figure is a vertical sectional view of an engine starter embodying the present invention.

Referring to the drawing, the device therein shown comprises a starter assembly including, in general, a motor l5, having a driving shaft l2 rotatably supported by end wall M of motor housing [6, a pinion [8 shown as integral with the shaft l2 meshes with planet gears 20. The planet gears 20 are rotatably supported by stub shafts 22 carried by spider cage 24 which is rotatably mounted on shaft l2 by sleeve bearing 25. The planet gear 20 meshes with a ring gear 28 securely fastened against rotation by screws 30 to gear housing 32. The gear housing 32 is secured to the motor housing l6 by screws 34 as shown or by other suitable means.

Integral with the spider cage 24 is a pinion 35 adapted to engage planet gear 38 which also engages the ring gear 28. The gears 38 are supported by stub shafts 40 carried by a drum member 52. The drum member 42 is journaled on the shaft [2 by the bearing 26 and by bearing surface 44 of the housing 32. A shoulder 46 on the drum 42 engages a shoulder 48 of the housing 32 to prevent axial movement of the drum 32.

The present invention provides a novel power transmission unit for driving engagement with a crank shaft 50 or extension thereof of the engine to be started. It comprises a helical spring member 52 terminated at one end by a shoulder 54 having splines 56 thereon for engagement with corresponding splines in the drum 52 for rotation.

therewith. A retaining ring 58 holds the member 52 in engagement with the drum 42. The other end is supported by a shell-like end portion 60 secured with the housing 32 to crank case 62 by studs 54. The end portion 60 is adapted to hold a friction ring 66 for frictionally holding one end of the spring member 52 to engage the latter to the crank shaft 50. The internal diameter of the spring member in its free position is slightly greater than the outer diameter of the shaft 52.

In operation when the motor 20 is energized rotary motion is transmitted from the motor Ill through the shaft l2 to the planetary gear train thus rotating the drum 42 which through the splined connection rotates the helical spring member 52. The ring 66 frictionally grips the free end of the helical spring member 52 causing it to wrap and close its diameter to frictionally grip the crank shaft. The friction ring is so proportioned as to have only sufificient friction force with the spring member 56 to cause it to grip the shaft and will permit the member 52 to rotate after the frictional force is overcome. Thus rotary motion to crank the engine is transmitted to the shaft 50. When the engine starts and rotates the shaft 50 at a greater speed than the drum 42 the friction exerted by the shaft 50 against the spring member 52 tends to unwind it and releases it from the shaft 50.

The openings 68 in the friction ring retainer permit oil vapors from the engine to enter and lubricate crank shaft 5|] and helical spring member 52. When thus lubricated, the spring member 52 limits the torque to a definite predetermined maximum value. Thus when the engine offers undue resistance to cranking, the

3 spring 52 will slip on the shaft 50 thereby giving overload protection. Also if the engine backfires the torque limiting action of the device protects the starter and engine from reverse rotation.

It has been found in use that the bearings 44 and 26, and the end Wall member [4 are sufiicient to prevent oil from entering the motor. However, it is understood that oil seals may be used if deemed necessary.

There is thus provided a novel starter in which a simple helical spring member replaces the usual spline nut, screw shaft, disc pack clutch and jaw clutch means.

Although only one embodiment of the invention has been illustrated and described, various changes in the form and relative arrangements of the parts, which will now appear to those skilled in the art, may be made without departing from the scope of the invention. Reference is, therefore, to be had to the appended claim for a definition of the limits of the invention.

What is claimed is:

In a starter for an internal combustion engine, the combination a driving member, a helical spring clutch member operatively connected at one end to said driving member, the other end of said helical spring member terminating in a rigid ring-like section, a driven member interposed in said helical spring member, said helical spring member including said ring-like section having a normal diameter slightly greater than the diameter of said driven member, a friction ring surrounding and in frictional engagement with said ring-like section, supporting means for said friction ring, said friction ring being so proportioned to frictionally grip said ring-like section upon rotation of said helical spring member in an engine cranking direction to cause said helical spring member to grip the driven member while permitting the helical spring member to be rotated by the driving member when the frictional force of the ring is overcome by the force of rotation of the driving member.

SAMUEL GILBERT.

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

UNITED STATES PATENTS Number Name Date 1,940,880 Pitter Dec. 26, 1933 2,322,608 Webster June 22, 1943 2,347,788 Nardone May 2, 1944

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