US2526127A - Engine starter - Google Patents

Description

Oct. 17, 1950 s. GILBERT 2,526,127

ENGINE STARTER Filed Sept. 18, 1947 Wig# f 4s 42 v Y 46 l2 99 l no 64 8f4 7B 7o l 3o O %6 5 u 2 Ja 12- A oe o`a 25 32 /70 u2 Q`se Wig JNVENToR. E14/UE L ELBEHT BY M 7 M Patented Oct. 17, 1950 Samuel Gilbert, Cedar Grove,

Bendix Aviation' Corporation, a corporation of Delaware N. J., assignor to Teterboro, N. J.,

Application September 18, 1947, Serial No. 774,718 42 Claims. (o1. 12a- 179) ThisV invention relates to engine starters and particularly to novel means, in a starter adapted for direct cranking operation, for advancing an engine engaging member into engagement with the engine for starting the latter. f

In a direct cranking starter, and in a combined direct cranking .and inertia starter, the direct cranking feature involves an engine engaging member or jaw which is required to be restrained against rotation to effect its axial movement yinto engagement with the engine.

In many applications of comparatively wide,k

but moderate temperature Varying range conditions, prior friction means, such as a split phosphor bronze ring, surrounding and biased against the jaw, has effected sufficient restraint.

However, with the field of operation of aircraft extended into colder regions, the simple friction means sometimes becomes ineffective, where fluid such as mixtures of oil, gasoline and other substances from the engine, enters and congeals', as between the threads of a screw shaft and a spline nut.

SuchV ineffectiveness is caused in part by the fact that the simple friction ring or means has a fixed value of friction or pressure, or a value that is intended to be fixedl so far as its ability to retain the value is concerned.

With respect tothe feature of congealing oil, asA aforesaid, several suggestions have been advanced whereby a direct cranking `starter jaw may be'caused to engage the engine jaw under frigid conditions, such as a suggestion of means for positively holding they starter jaw until it engages the engine jaw and then releasing it Vfor rotation to start the engine.

The latter suggestions involve structure which, although not complicated in consideration of the results obtained, are naturally not so simple as the former elemental friction means which fails under frigid conditions as stated.

An object of the present invention is torprovide means which is substantially as simple as the fixed value friction means above noted, but which automatically varies the value of the frictional counterforce on the starter jaw to any value necessary to prevent rotation of the member.

Another object is to provide a wrap spring friction ring, providing for direct cranking starter jaw engagement with an engine, which is effective to give sufficient torque for cold starting when the screw shaft is subjected to engine oil.

Another object is to provide engine starter jaw advancing means which is simple and durable in construction, economical to manufacture, and effective in its operation. l

TheY 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 inven.

tion is illustrated by way of example.

In the drawing: Y. l Figure 1 is a side view, generally in section having parts in elevation, of va portion of an engine starter embodying the invention; and Figure 2 is la`detail side section of a wrap spring seen in Figure 1.

VReferring to Figure 1, a starter III comprises,

in general, a bale I2, an engine engaging member-- I4, associated with the bafe I2, and having ani end jaw I6, a shank portion I8 of certain diameter disposed next to the jaw I6 and a shank portion 20 of smaller diameter behind the first shank portion I8 joined thereto by a ramp 22.

The member I4 is adapted to be restrained against rotation for axial movement of the jaw I6 into engagement with an engine jaw 24, and means provided for rotating the member I4 to effect such axial movement and to rotate the same to start the engine, as is further pointed out. For combination with the above-mentioned 'ele' ments, the invention comprises a resilient or exible element, such as a flat Vstrap 2B of phosphor bronze, see also Figure 2, connected adjacent t0 one end`28, as by an anchor rivet 30, to the bale I2, and having a portion or convolutions 32 helically wound edgewise about the member I4 to a free end 34 of the strap 26 and responsivel to rotativeforce on the member I4 for cooperation with the shank portion I8 to restrain they member 'I4 against rotation. The strap 26 and the shank portions I8 and 2E) are related to the jaw I6 such that, when the latter has reached,

its operative position for starting the engine, thestrap 26 has axially ridden off the shank portion I8 and down the ramp 22 to free the 'member I4 from rotative restraint by thestrap 26.

In further particular, the Astarter I0 comprisesv a housing portion 38 having a flange 40 for mounting the starter, as by studs 42, to an engine crank case 44, and a flange 46 for supporting a housing 48 of a motor 5U having a rotor 52 and a shaft 54. The latter is journaled, as by a bearing 56 in a partition 58, and carries a pinion or sun gear 60.

VThebafe I2 comprises a member 62 to which the strap 26 is riveted, and a member 64 secured to the member 62 having a iiange 65 between the iiange 49 and the engine case 44.

The Sun gear 69 meshes with planet gears 69, which mesh with an orbit gear 'l0 on the housing 38, and are mounted on a carrier 'l2 having a sun gear 14. The latter meshes with planet gears 16, which mesh with the orbit gear 7D and are carried by an end wall 'I8 of a barrel 86 rotatably mounted in the housing 38 and having a stub shaft 82 on which the sun gear 'I4 is journaled.

A torque limiting disc pack 84 has interlayered discs axially movably splined, but rotatively xed, to the .barrel 80 and to an axially stationary rotative nut 86, respectively, the friction between the discs being adjusted by springs 88, a ring nut 99 threaded in the barrel 89, and other elements in a usual manner.

A screw shaft 92, having long-lead thread relation to the nut 86, has an axially slidable spline connection 94 to the jaw member le.

A mesh rod or member 96, held by a nut S8 in an opening in a central web portion of the-member I4, compresses a sealing ring 99 against the web, and is provided with a iange |99 behind a iiange |92 of the screw shaft 92. A spring Ill extends between the flange |06 and a backing ring |06 held to the shaft 92, as by a lock ring |08 in a groove in the shaft 92.

A seal ring I9, fixed to the baiile member 64, is maintained around the nut 86, as by a garter spring H2, in radially inwardly pressing sealing engagement with the nut.

vIn operation, with the parts in the inactive positions shown, corresponding to the retracted position of the jaw I6, the convolutions of the strap 26 engage the shank portion l to effect a predetermined degree of friction with this shank portion when the member Ul tends to rotate. This degree is such that, as in warm weather or when the parts are warm, for instance, the strap will operate substantially as an ordinary split friction ring, to restrain the member I4 from rotation, the jaw I6 then being moved forward into engagement with the engine jaw 24, because of the screwaction of the screw shaft 92 within the spline nut 86.

However, where, as under cold conditions, above mentioned,-the member |11 has a, greater` tendency to rotate with the screw shaft 92, caused as by being held sealed to the shaft by congealed oil, and requires greater force to break such seal, the strap 26, by reason of its wound relation to the shank portion I8, will wind more tightly on this shank portion. The tightness of this latter winding action will be substantially in accordance with :'2

the strength required to break the congealed oil, so that the wrap spring 26 will restrain the member 4 vagainst turning or oppose the turning force with Aany one of several eounterforces, dependent upon the torque required or the degree of congelation of the oil.

' Although only one embodiment of .the invention has been illustrated and described, various changes in the form and relative arrangements of the parts may be made to suit requirements.

What is claimed is:

1. In an engine starter comprising a baliie, an engine engaging member extending through said baille having an end jaw, a shank portion of certain diameter disposed next to the jaw and a shank portion of smaller diameter behind the first shank portion joined thereby by a ramp, said member being adapted to be restrained againstrotation for axial movement of the jaw into engagement with the engine, and means for rotating the member to effect said axial movement and to rotate the same to start the engine, the combination of a resilient at strap connected adjacent to one end to said baille and having a portion helically wound'edgewise about the member to a free end of the strap and responsive to rotative force on the member for cooperation with said rst shank portion to restrain the member against rotation, said strap and said shank portions being related to thel jaw such that, when the latter has reached its operative position for starting the engine, the strap has axially ridden off said first shank portion and down said ramp to free the member from rotative restraint bythe Strap.

2. In an engine starter comprising a baie, an engine member having a shank extending through said baiTle, said shank having two shank portions, one of said portions being adapted to be restrained against rotation for axial movement of said member into engagement with'the engine, and means for imposing rotative force on said member to eifect said axial movement and rotate the same to start the engine, the combination of restraining means for said one shank portion connected adjacent one end of said restraining means to said baille and having a portion wound about said one shank portion to a free end of said resilient means and responsive to said force for cooperation with said shank to restrain said member against rotation when in a disengaged position from said engine, and a second shank portion adjacent said first shank portion and including means for releasing said restraining action of said resilient means when said member is in engaged position with said engine.

SAMUEL GILBERT.

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

UNITED STATES PATENTS Number Name Date 1,126,780 Jones Feb. 2, 1915 1,298,975 Lindsay Apr. l, 1915 1,303,503 Schnuck May 13, 1919 2,262,333 Nardone Nov. 11, 1941 2,424,494 Nardone July 22, 1947 FoREiGN PATENTS Number Country Date 239,316 Great Britain Sept. 10, 1925

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