US2619815A

US2619815A - Starter

Info

Publication number: US2619815A
Application number: US15290A
Authority: US
Inventors: Romeo M Nardone
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1944-03-07
Filing date: 1948-03-17
Publication date: 1952-12-02
Anticipated expiration: 1969-12-02

Description

1952 R. M. NARDONE ,6 5

STARTER Original Filed March '7, 1944 2 SHEETSSHEET l I N VEN TOR.

RbmeoMNazdone,

ATTORNEY Dec. 2, 1952 NARDONE 2,619,815

STARTER Original Filed March 7, 1944 2 SHEETSSHEET 2 Q V INVENTOR.

RonaeoM/Vardozze.

A TTURNEY Patented Dec. 2 1952 Bendix Aviation Corporation, Teterboro, N. J., a gre t on qfs e a Original, application, March 7, 1944, Serial vN0.

Divided and this application March 2 Claims.

The invention hereof relates to starters for,

internal combustion engines and particularly to starter torque limiting means. This application is a divisionof copending'application, Serial No. 525,417, filed March 7, 1944,

for a Starter, now Patent No. 2,446,297.

' In a starter of the type indicated, it is usual to employ torque limiting means between an electric motor or driving member anda start-er. clutch member or jaw which engages a complemental engine clutch means or jaw to start the engine.

While a certain range in the torque transmitting properti-es or" the torque limitin device is permissible, conditions of overload are often created and it becomes necessary to accommodate such conditions in the torque limiting mechanism.

An object of the present invention is to provide a novel and improved torque limiting means of the type indicated.

Another object is to provide torque limiting means which employs the principle of a screw or cam having rotative movement about the screw axis for separating torque members along the axis against a force biasing the members together.

Another object is to provide means of the above-indicated. character which is simple and durable in construction, economical to manufacture, and effective in its operation.

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

In the drawing:

Figure 1 is aside view generally in section, but having parts in elevation, of a starter] embodying the torque limiting means of the inventionj and Figure'2is an exploded perspective'oi parts of the torque limiting means shown in Figure '1.

Referring to Figure 1, a starter for which the improvement of the invention is adapted, oomprises a housing including portions I and II having clamped therebetween a flange l2 of a bearing partition 13. provided with a radially outerflange IA formed with bolt openings l5, whereby it is adapted to be bolted to the crankcase of an engine.

Mounted on the left end of the housing portion as hown andextendine over the flange 1.4, is an end closure, or, baffle iihaving a central openi .deflned by a portion I1. oivsubstantially cup -shape, An ,oil seal.l8,,carried by the portion 1. surrounds and, .engagesadrivesleeve orsplin ut I 9, which extendsgintogthe. housing, ortion In V w The inner end of the nut l9 carries a packing assembly 20, including a radially outer flange The housing portion 10 is 2, 2| axially, engaged by the end. of the sleeve 19. The.assembly'illalsoincludes an inner seal which surrounds and engages an enlargement, 23

of .a meshing or thrust rod. The. latter has a forwardly extending part 25 of reduceddiameter forming a shoulder 23 on the enlargement23.

The inner surface of the spline nut l9 is--provided with long-lead screw threads 27. A screwshaft 28, which has threads 29 complemental to the threads 21, is disposed within the nut I3 and has abore 30 vreceiving the extension 25 of the rod 24. At the left end of the-screw shaft 28, the bore 30 is enlargedto provide a springreceiving recess 3|, which receivesone end-of-an expansion spring 32 disposed about the thrust rod extension 25. The other end of the, spring 32 engages a clutch member or jaw element'33 slidably. spline connection .33 to the screw shaft 28.v The mesh rod extension 25=extends through an opening in a center web of the jaw membe 33 to an outer end of the rod carrying anut -36.-

As the rod 24 is moved. to theleit', as shown in Figure 1, the shoulderZfi engages, and causesa corresponding movement of, the screw shaft28.. Thus, the jaw 33 is moved into operative engage-- ment with a complemental jaw 31 which, inthis: instance, is carried by the engine crank-shaft. The spring 32 provides for ratcheting of the jaw 31 on the jaw 33 when the engine starts andbefore the withdrawal of the jaw 33.

A torque-limiting friction disc pack 394s dis posed within an annular space radially between the spline nu-t l9 and a sleeve 40, with interspersed ring-like discs axially movably splined to the nut and the sleeve, respectively, as on splines 38 on the outer cylindricalsurface of the 1111B l9. The S16BVB 49\,113 S.%1|I1. inwardly turned end flange 4 I A spacer ring 42, Figure 1,: is interposed be.- tween the end flangeil and the disc pack 33.

Likewise, a spacer ring 43. is interposed between the other end of the disc pack :and the iendtwall lli of a barrel in the casing section [3.

Referring to Figure 2, the inner surface-oi the barrel 45 carries "helical splines or long-lead screw threads 46 which fit between complemental splines or threads 41 on the exterior of the clutch sleeve 40.-

The barrel 45 is mounted for rotation by'a bearing 48 and a bearing ring 49 at opposite ends of the barrel. A ring nut 50 is threaded-into the outer end of the barrel 45 tothe left of a spring positioning ring 5!. As indicated by dotted linesin Figure 2, the inner face of the ring 5| is-provided with a plurality of recesses 52, -the sides of which are defined by arcs. Pins 53 project from the centers of the recesses 52. Received in each of the recesses 52, and positioned thereby, is an outer expansion coil spring 54. An inner expansion coil spring 55 is disposed within each outer spring 54, and has one end fitting over one of the pins 53. The other end of the inner spring 55 fits within one of recesses 56 formed in the end flange 4| of the sleeve 45. The corresponding end of the outer spring 54 engages the flange 4|.

Springs 54 and 55 may be employed to exert a given thrust on the clutch sleeve 49, and which thrust is transmitted throughout the spacer ring 42 to the disc pack 39. However, the barrel 45, which is driven by planetary gearing, later set forth may, by reason of variations in the load encountered, vary the eflective force on the disc pack 39 because of the interfitting helical splines 48 and 41. When the torque increases, the helical splines 45 and 41 are rendered effective to relieve the pressure provided by the assembly of springs 54 and 55. Thus, the friction disc torque limiting device may be set to have its torque transmitting properties maintained within a certain predetermined range.

Extending inwardly from the end wall 44 of the barrel 45 are a plurality of stub shafts 51. R- tatably carried by each of the stub shafts 51 is a planet gear 58. The inner surface of the housing portion [0 adjacent to its right-hand end is provided with an internal orbit gear 59.

The plant gears 58 mesh with the orbit gear 59 and also with a sun gear 65 rotatably mounted on hollow stub shaft 6! which extends to the right from the end wall 44. The shaft BI is provided with an inwardly extending shoulder 52. The outer, or left-hand, end of the stub shaft 8! receives the enlargement 23 of the shaft 24.

Operatively connected to the sun gear 50, as by being integral therewith, is a planetary gear carrier 63 having a plurality of stub shafts 54 projecting therefrom. Rotatably carried on each of the stub shafts B4 is a planet pinion 65 which meshes with the orbit gear 59, and another sun gear 56. The latter rotates on the sleeve-like shaft 6! and also carries a planet gear carrier 61 provided with stub shafts 68, each of which carries a rotatable planet gear 59.

The planet gears 59 mesh with an internal orbit gear 13 carried by the bearing partition I3. The planets 69 also mesh with a pinion 'H on one end of an armature shaft 12.

The bearing partition 13 has an inwardly extending web 8 which carries a bearing assembly 9 supporting the left-hand end of the armature shaft 12.

Drivably carried by the armature shaft '52 is a flywheel 13, which with the shaft, a commutator 74, and pinion H, and appurtenant parts constitutes a rotatable unit.

The field windings T of the motor are electrically connected to terminals in an outlet 15 on the housing portion H.

The rod 24 has a reduced portion at the shoulder 62 and extends past this shoulder through the sleeve 5| into the bore 71 of the armature shaft 12. Within the bore H, the rod is connected to another thrust rod 18 which extends beyond the right end of the armature shaft, and is slidable in a sleeve 19 carrying a bevel gear 80.

A connection 8!, between the thrust rods 24 and 18, provides an abutment for one end of an expansion spring 82. This spring 82 surrounds the rod 24 and bears at its other end, against the shoulder 52. The tendency of the spring 82 is to retract the thrust rod 24 and clutch jaw mem ber 33.

In operation, after the starter jaw 33 has been actuated to engagement with the engine jaw 31, and the driving members to the left of the pinion H are under the driving force of the latter, since the barrel is axially stationary, if the frictional characteristic or torque slip value of the pack 39 has increased over the value to which it was adjusted by the springs 54 and 55, and a greater torque is encountered, the splines 46 will act on the splines 41 with a screw-like action urging the sleeve 48 axially to the left, as shown, against the forces of the springs 54 and 55. This action momentarily separates the inner and outer discs of the pack 39 from each other.

If the aforementioned adjusted frictional characteristic or torque slip value of the pack 39 does not increase, the mentioned screw action will not occur to axially separate the discs of the pack 35, but the discs of the latter Will frictionally slip relative to each other when the adjusted valve is exceeded.

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, a clutch member adapted for cooperation with engine clutch means to start the engine, a rotatable barrel driving member, a sleeve concentric of said barrel and helically spline connected thereto, a friction disc pack within said sleeve and yieldably connecting said clutch member and sleeve, spring means acting upon said sleeve for biasing the discs of the pack into engagement with each other and opposing relative movement between said barrel and said sleeve while permitting driving rotative movement of said barrel and sleeve together, said spline connection having a pitch angle to cause relative axial movement between the sleeve and barrel in response to a predetermined load on said sleeve to overcome said spring means thereby to disengage the discs of the pack.

2. In an engine starter, a clutch member adapted for cooperation with engine clutch means to start the engine, a rotatable barrel driving member, a sleeve in the barrel having an end flange and including a helical splined connection to the barrel, a friction disc pack within said sleeve and yieldably connecting said sleeve to said clutch member, a ring nut in the barrel, expansion springs between the end flange and the ring nut for urging the discs of said pack into frictional engagement with each other, and said spline connection having a pitch value effective upon a load in excess of a predetermined value being applied to the sleeve for moving said sleeve axially in opposition to said springs to disengage the discs of the pack from each other.

ROMEO M. NARDONE.

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

UNITED STATES PATENTS Nardone Aug. 3, 1948