US2688254A

US2688254A - Starter jaw meshing apparatus

Info

Publication number: US2688254A
Application number: US288892A
Authority: US
Inventors: Gilbert Samuel; Charles S Metsger
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1952-05-20
Filing date: 1952-05-20
Publication date: 1954-09-07
Anticipated expiration: 1971-09-07

Description

Sept 1954 s. GILBERT ETAL 2,688,254

STARTER JAW MESHING APPARATUS Filed May 20, 1952 FIG. 1

FIG. 2 FIG. 3

INVENTORS SAMUEL G/LBERT CHARLES S. METSGER m Patented Sept. 7, 1954 24688354 I STARTER .TAW MESHI'NG' APPARATUS Samuel. Gilbert, Cedar Grove; and Charles. S.

Metsger; Rochelle Park, N. J. assignors to-Bendix Aviation. Corporation; Teterboro, N.. .L, a

corporationof Delaware.

Application May 20, 1952, Serial No. 288592 3 Claims. 1

The present invention relates to-engine starters and more particularly to jaw meshing mechanism for an engine starter.

In engine starters of the. type having a splined screw shaft, it has been found necessary to provide' some means of restraining the starter jaw against rotation to cause axial movement of the screw shaft to move the jaw into engagement with a mating jaw on the'engine to be started. Heretofore, a friction ring surrounding the starter jaw has been used. The friction ring has the disadvantage in that the friction is present throughout the entire cranking cycle. With the advent of the turbine type engines which require a high cranking speed the problem has increased. The sustained friction not only reduces the efficiency of the starter, but also produces excessive wear to reduce the effectiveness of the friction ring.

The present invention provides friction means for initially restraining the starter jaw against rotation with the friction being removed as the starter increases in rotational speed so that there is substantially no friction drag during the cranking cycle.

It is an object of the invention to provide an improved engine starter.

Another object of the invention is to provide novel jaw meshing means for an engine starter.

Another object of the invention is to provide novel friction means for restraining a starter jaw against rotation.

Another object of the invention is to provide an improved starter adapted for operation at high speeds.

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 inven tion is illustrated by way of example.

In the drawing:

Figure 1 is a partial cutaway view of an engine starter embodying the invention.

Figure 2 is a side view of one of the friction shoes.

Figure 3 is an end view of one of the friction shoes. 4

Referring to the drawing, an engine starter is indicated generally by the numeral 5. Only that portion of the starter 5 illustrating an embodiment of the invention is shown in detail, but it is understood that it comprises a driving source and associated gear train. An axially stationary spline nut 6, which may be connected for rotation by the gear train in any conventional manner as 2 is known: to the: art. has internalsplines; 1 adapted tor-mesh with; externalsplines 8 of screw shaft 9.

The screw. shaft. Slhas: internal, splines H! adapted; to mesh with external splines; II onstarter jaw 12.. The; starter jaw it. is held. into operative engagement with the screw shaft May a mesh rod id; A ratcheting spring it is: positionedbetween the mesh rod l3 and a spring restraining ring l5 secured in the screw shaft 9. A shoulder IS on the mesh rod I3 limits the outward travel of the mesh rod l3 with respect to the screw shaft 9. An oil seal ll surrounds the spline nut 6 and is secured in position by a baiile plate l8.

A novel feature of the present invention is the arrangement of the friction means. The jaw l2 has a circumferential flange I9 as an integral part thereof. The flange 19 has an axially extending portion 20 which has a plurality of slots 2| spaced around the circumference thereof. Shoes 22 (see Figures 2 and 3) are inserted in the slots 2| and held against an axially extending flange 23 of an outer baffle plate 24 by a garter spring 25. The plate 24 is secured to the starter housing in any conventional manner such as, for example, being clamped between the starter housing and the mounting flange (not shown) of the engine to be started. A lip 26 on the flange 23 maintains the shoes 22 in an operative position.

The shoe 22 has a shank portion 21 which has a groove 28 adapted to receive the garter spring 25 and a contact portion 29. The shoes 22 may be of any suitable bearing material such as bronze, metalized brush material or the like.

In operation, the spring 25 urges the shoes into contact with the flange 23 under a tension that will give the desired friction to restrain the jaw l2 against rotation and axial movement of the jaw is obtained. The slots 2| in the flange 20 permit axia1 movement relative to the shoes 22. Upon the jaws meshing, the friction of the shoes 22 is overcome and the shoes 22 are rotated by the flange 20. Upon the speed of rotation increasing above a predetermined value, centrifugal force causes the shoes 22 to move radially outward against the force of the spring 25 thus removing the frictional drag of the shoes 22. Thus, it can be seen that at operational speed, the frictional force is removed. The shoulder on the contact portion 29 comes into contact with the inner diameter of the flange 20 an limits the outer radial movement of the shoes.

Although only one embodiment of the invention has been illustrated and described, various changes in the form and relative arrangement of the parts, which will now appear to those skilled 3 in the art, may be made without departing from the scope of the invention.

What is claimed:

1. Apparatus for use in an engine starter having a rotatable and axially movable screw shaft, comprising a starter jaw splined to said screw shaft for rotation with and axial movement relative thereto, spring means for urging said jaw to an extended position upon axial movement of said screw shaft, a stationary bafile member, a flange member on said starter jaw, a plurality of friction shoes mounted in said flange member for rotation with and axial movement relative thereto, and spring means for biasing said friction shoes into engagement with said stationary bafile member, said friction shoes being responsive to centrifugal force to remove the bias of said spring upon the rotation of said starter jaw.

2. Apparatus for use in an engine starter having a housing and a rotatable and axially movable screw shaft, comprising a starter jaw splined to said screw shaft for rotation and axial movement thereby, a baffle plate secured to said housing and having an axially extending flange, a. plurality of friction members carried by said starter jaw, spring means for biasing said friction members into frictional engagement with said flange,

said friction members being responsive to centrifugal force to overcome the bias of said spring means upon the speed of rotation of said starter jaw exceeding a predetermined value.

3. Apparatus for use in an engine starter having a housing and a rotatable and axially movable screw shaft, comprising a baflie plate secured to said housing and having an axially extending flange, a plurality of friction members carried by the flange, spring means for biasing said friction members into frictional engagement with said flange, and means connected to the screw shaft adapted to drive the friction members over the flange upon rotation of the screw shaft, said friction members being responsive to centrifugal force to overcome the bias of said spring means upon the speed of rotation of said screw shaft exceeding a predetermined value.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,441,418 Halbleib Jan. 9, 1923 FOREIGN PATENTS Number Country Date 30,784 France Aug. 23, 1920