US2429425A - Driving mechanism - Google Patents

Description

Oct. 21, 1947. R. M. NARDONE DRIVING MECHANISM Filed Sept. 24, 1942 7 Sheets-Sheet 1 Oct. 21-, 1947.

R. M. NARDONE 7 2,429,425 DRIVING MECHANISM Filed Sept. 24, 1942 7 Sheets-Sheet 2 Romeo M Mlle.

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R. M. NARDONE 2,429,425 DRIVING MECHANISM Filed Sept. 24, 1942 7 Sheets-Sheet 4 Oct. 21, 1947. R. M. NARDONE 2,429,425

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DRIVING MECHANISI Filed Sept. 24, 1942 7 Sheets-Sheet 6 DRIVING MECHANISM Filed Sept. 24, 1942 7 Sheets-Sheet 7 Patented Oct. 21, 1947 DRIVING MECHANISM Romeo M. Nardone, Westwood, N. J., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application September 24, 1942, Serial No. 459,550

This invention relates to driving mechanism, and particularly to driving mechanism of a selective engagement character, wherein the transmission of torque may occur through one or the other, or both, of a pair of driving units; each of which is normally in the non-driving position.

Copending application, Serial No. 506,587, filed October 16, 1943, on Driving mechanism, is a division hereof.

An object of the invention is to provide a novel construction and method of operation of such a driving mechanism.

A second object is to control such a driving mechanism in a manner enabling the driven load to freely over-run a retarding element when moving in one direction and to afiect the driven load by a retarding element to tend to stop reverse movement. This is of special importance in the actuation of aircraft landing gear, the improvement of the operation of which constitutes a third object of the invention.

A fourth object is to provide yieldable clutch means of novel construction, and control means therefor adapted to regulate the clutch capacity in such manner as to tend to maintain the torque transmitting capacity constant irrespective of variations in the condition of the clutch surfaces.

Another object is to provide aircraft landing gear operating mechanism embodying various features of improvement over its prototype, as disclosed in Allen Patent No. 2,284,353 granted May 26, 1942.

These and other objects will become apparent from inspection of the following specification when read with reference to the accompanying drawings wherein is illustrated the preferred embodiment of the invention. It is to be expressly understood, however, that the drawings are for the purpose of illustration only, and are not de signed as a definition of the limits of the invention, reference being had to the appended claims for this purpose.

In the drawings:

Fig. l is a longitudinal sectional view of one driving unit of the mechanism embodying the invention;

Fig. 2 is a view looking toward one end of the unit shown in Fig. 1;

Fig. 3 is a view from the opposite end, with a part of the housing broken away;

Fig. 4 is a view of the field coil assembly for one driving unit;

Fig. 5 is a view of said field coil assembly as it appears before installation;

Fig. 6 is a view of one or the clutch parts;

6 Claims. (01. 192-.02)

Fig. 7 is another view of the same clutch part;

Fig, 8 is a sectional view on line 88 of Fig, 9;

Fig. 9 is a view of one of the planet assemblies;

Fig. 10 is a view oi one of the driving discs of the clutch assembly;

Fig. 11 is a view on line II-|l of Fig. 10;

Fig. 12 is a view of one of the driven discs of the clutch assembly;

Fig, 13 is a view on line I3--i3 of Fig. 12;

Fig. 14 is a view of the other planet gear assembly;

Fig. 15 is a view on line I5I5 of Fig. 14;

Fig. 16 is a view of the clutch. barrel;

Fig. 17 is a view on line II-II of Fig. 16;

Fig. 18 is a view of the clutch abutment plate;

Fig. 19 is a view on line I9.-|9 of Fig. 18;

Fig. 20 is a view of the intermediate driveshaft;

Fig. 21 is a diagram illustrating the operation of the clutch pressure controlling means;

Fig. 22 is a view on line 22-22 of Fig, 20;

Fig, 23 is a view on line 23-23 of Fig. 20;

Fig. 24 shows a contact assembly;

Fig. 25 is a schematic illustration of the electrical connections for one driving unit;

Fig. 26 is a simplified schematic diagram of said electrical connections; and

Fig. 27 shows the manner of mounting two driving units, and the connections therefrom to a landing gear.

The embodiment illustrated includes a pair of driving units 14 and I14 (Fig. 27), each having two stages of planetary gearing in series (Fig. 1) driving a barrel l which, in turn, drives sleeve 2 through a set of steel balls 3 and a cam plate 4 keyed to the sleeve 2. As shown best in Figs. 6 and '7, the inner surface of sleeve 2 is splined, and there is also an annular ledge or shoulder I34 at the ends of the splines, which shoulder engages a similar shoulder on an annular plate 5 having pockets to receive springs I24; there being similar pockets I25 (see Figs. 18 and 19) in an abutment plate I2I having notches I22 to receive pins I23 which hold the. two spring receiving plates 5 and l2l against relative rotation. Torque transmitted from barrel I to cam 4 through the balls 3 tends to move cam 4 (see Fig. 21) as well as sleeve 2 to the left, whereupon shoulder |34 acts against spring plate 5, thereby partially relieving the pressure of the clutch springs on the clutch discs H3, M4; the driving discs 3 being coated with powdered metallic friction material which is bonded thereto, as shown at H5, H6 (see Fig. 11) while the driven discs II4 are uncoated, and disposed in interleaving engagement with discs H3. Normally the spring pressure on the clutch is com siderably higher than required to transmit the drive from sleeve 2 (to which clutch discs H3 are splined) to sleeve 48 (to which clutch discs H4 are splined). The separating force of the balls 3 against the two cam surfaces is transmitted to plate 5 by way of shoulder I34 (Fig. 6) and thus relieves a part of this spring pressure. lowering the torque to the correct value. Should the co-efiicient of friction between clutch plates H3 and H4 increase for any reason, the torque required to slip the plates would also increase. This would produce a greater separating force due to the balls, relieving more of the pressure of springs H24 upon the plates H3, H4 and thereby tending to compensatingly reduce the torque transmitted. A substantially constant torque output results from this construction; that is, slipping will always occur at substantially the same predetermined torque value (turning effort) regardless of the condition of the interengaged friction surfaces of the clutch.

The driven shaft 6 (to which sleeve 48 is keyed) carries a movable jaw I mounted on and driven through the agency of balls mounted in a cage 8 (see Figure 23). Jaw I is caused to move to the left to engage a similar jaw on shaft 9 by the action of a solenoid Hi. This solenoid is connected in the motor circuit as shown in Figs. 25 and 26, so that when the current is caused to flow to commutator Hill of the motor, the solenoid in also is energized to immediately engage the jaw I with the jaw 9. When the current is turned off, a spring ii acts to separate the jaws and bring I back to its normal disengaged position.

The principal reason for the use of the normally disengaged clutch between the intermediate drive shaft 6 and the driven shaft 9 is to facilitate operation of the landing gear to which the shaft I50 (Fig. 27) is drivabiy connected, by either of the two units, 94 or 194, independently of the other, although both motors may, on any occasion when desired, be operated together, thus doubling the driving effort.

In addition to the use of the load-responsive cam mechanism above-described, the invention includes other features directed to the same general purpose of maintaining a smoothly operating, uniformly effective driving effort all the way from the armature shaft 21' to the load-engaging driven shaft 9. These other features are described in the paragraphs immediately following.

Each planet pinion of each of the two planetary gear sets receives a ball bearing assembly, and each ball bearing assembly is securely locked in concentric alignment with the mounting pin of the corresponding planet cage or carrier, one of which cages is designated by the reference character 23 in Figs. 1, 8 and 9, while the other is designated by the reference character 24 in Figs. 1, 14 and 15. As shown in Figs. 8, 9, l4 and 15, the method employed to insure and to maintain correct concentric relationship of each pinion to its axis of rotation, involves the provision of locking elements 25, 21, 28, 29 and 30 for the pinion bearings 3i, 32, 33, 34 and 35, respectively, each of which locking elements is secured to its associated mounting pin by means of a screw which is received in both said locking element and mounting pin at a point which is eccentric to the common aXis of said elements, and hence eccentric to the axis of rotation of the associated planet pinion; the eccentricity in each case being in a iii direction coinciding with a radial line drawn from the longitudinal axis of the planet cage to the central meshing point as between the associated planet pinion on the one hand and the common orbital gear 4! constituting the track about which the planet pinions revolve. By this method the maintenance of correct concentric relationship is assured, because the specified eccentricity of position of the attaching screws 42 effectively counteracts and defeats the tendency toward unscrewing which characterizes the mounting means commonly employed in the prior art in connection with the use of planetary sets of gears of the character herein employed.

Another feature directed to the same general purpose, above-identified, is the use of the cage 24 for the planet pinions 33, 34 and 35 instead of directly mounting these planets on an end sur' face of the clutch barrel 1 as has been customary heretofore. By utilizing separate pieces of material from which to fashion the planet cage 24 on the one hand and the end of the clutch barrel 1 on the other, and by thereafter uniting one to the other by the dowel method indicated at 46 in Figs. 1, 16 and 17, the accurate machining of each part is facilitated and a more precise concentric relationship is thereby assured, particularly in that this divided arrangement permits the use of a ball bearing assembly between the elements 24 and l on the One hand and the sleeve portion 48 of the intermediate drive shaft 6 on the other; such ball bearing assembly being indicated at 49 in Fig, l as located by and between cooperating circular shoulders on the elements 1 and 48, respectively, which location is rendered even more precise by the positioning of the clutch sleeve 2 in such manner that its hub portion 5! is in full registry with the end face of the inner race of the bearing assembly 49. The use of this construction also facilitates precise concentric location of the entire gear train because the same shouldered portion of the sleeve 49 provides an annular space in which the ball bearing assembly 58 may be received, which assembly in turn constitutes concentric supporting means for the reduced end por tion 51 of the armature shaft 2i and thus assures that the two sections of the gear train, through which the said armature shaft extends, will be held in correct alignment with the hearing assemblies 49 and 56 as well as with the sleeve 48 of the intermediate drive shaft 6,.

True alignment between the sleeve 48 and the shaft 6 is assured by provision of semi-circular keys 63 fitting in diametrically opposed slots milled in the shaft 6, and a transversely disposed taper pin 84 (see Fig. 22) extending completely through the head portion 67 of the shaft 6 which terminates at a point within the bearing assembly 49, which latter fact also contributes to the preservation of a true concentric relationship and precise driving alignment of the parts.

Precise driving alignment and uniformly maintained driving effort are further assured by the use of the ball containing cage 8 above referred to, the said cage being interposed (see Fig. 23) between the splined portion SI of the shaft 6 and the correspondingly splined and axially shiftable clutch element 1, the axial shift of which is brought about by reason of its constituting a part of the magnetic circuit which results from the passage of current through the winding of the solenoid iii. If the connection between the shaft 6 and the clutch element 7 were of the conventional splined type, it would require a relatively greater amount of axially directed force to produce axial movement simultaneously with transmission of torque from the element 6 to the element 1; and the incorporation of a structure suffi- I the ball-containing cage 8, and by the positioning of the balls therein in such relation to the recesses in members 6 and 1 (see Fig. 23) as to produce a maximum of assistance to the smooth transmission of the driving effort from the part 5 to the part 1.

The driving motor is of the direct current type, with field windings in shunt relationship to each other, but in series relationship to the armature winding, the latter being indicated in Figs. 25 and 26 by its commutator terminus, shown at I00.

Solenoid I0 is shown as connected in a parallel branch 80 of the motor circuit, and in Fig.1 conductor 80 is shown as located completely within the motor housing 14, along its inner surface, and adapted to connect electrically with solenoid lead 8| by way of an intermediate automatic connector shown best in Fig. 24, and including a flexible lead 86 anchored at either end in bushlugs 84, 85 of conducting material and urged into good electrical contact with conductor terminals 9i, 92, respectively, by the action of a spring 81; the lead 86 being of slightly greater length than the actual distance between'the facing ends of housing sections 14 and 94 so as to assure maintenance of axial pressure on bushings 84' and 85 by the action of spring 81, and hence good contact with the inner metallic cores of the terminals 9i .and 92, respectively.

In assembling the complete mechanism, the terminal 9i is installed before attachment of housing section 82 to housing section 94 by bolts 95. After housing section 84 has been attached, automatic connector assembly 86 is then inserted in insulating tube 83, after which housing section 14 is attached; and as bolts 96 are made fast the electrical connection of members 92 and 85 is automatically established.

The actual physical arrangement of the field coil connections is simulated in Figs, 4, 5 and 25, while Fig. 26 shows the same connections in more schematic fashion, in order to show more clearly the different paths for current flow, depending upon which of the two directional switches I04, I05 is in closed position.

Closure of switch I05 energizes field coils IF and 3F (and, of course, the armature windings I00 as well as the winding of solenoid I0), and

this energization of the field coils IF and 3F produces rotation of the motor in the direction corresponding to the direction of the windings IF and 3F in relation to the armature circuit. Conversely, closure of switch I04 produces rotation of the motor in the opposite direction by reason of the opposite direction of winding of the field coils I 2F and 4F which are in circuit only with the switch I04, although in series relation to the armature and solenoid windings. In other words, the solenoid winding I0 is energized Whenever either of switches I04 and I05 is in the closed position, and therefore the jaw clutch 1 is moved to the engaged position whenever the motor is energized whether for clockwise or for counterclockwise rotation. As soon as the motor circuit is broken the spring II is ei'l'ective to return the clutch member 1 to the disengaged position indicated in Fig. 1, as the current flow to the solenoid I0 is interrupted simultaneously with the opening of the switch I04 or I05, as the case may be.

' enter, but without impairing the radio-shielding properties of the strap.

The abutment plate I 2i is held against axial displacement by an assembly of thrust absorbing elements including a locking ring I29 interposed between ball-race I21 and nut I28. This ring I29 has an inner tab fitting into a slot in sleeve 48 and outer tabs that are bent over the outer surface of nut I28; the combined effect of the tabs being to hold the assembly against movement either angularly or axially.

The exposed portion of driven shaft I50 (Fig. 27) is adapted to receive a lever connecting dircctly with the landing gear (not shown) and therefore said shaft I50 is under load from the weight of the landing gear, in all positions except when the gear is fully extended in landing positions, The shaft 9 of unit 94and the same is true of unit I94siips into, and drives, a pinion 20I; each of said pinions 20I being separately mounted in ball bearing assemblies 202 supported on the bosses 203, 204 which carry the units 14, I14, respectively. Each unit may thus be readily removed for servicing or replacement.

The two pinions driven by the units 14, I14 mesh with and drive a large gear 206 on a central shaft I48. A pinion on this shaft I49 drives a double planetary gear reduction set (208, 209) to the output shaft I I50 of the mechanism. -The planet gears (208, 209) oi both planetary sets are mounted on roller bearings (2I0, 2I I). The output shaft I50 is mounted on bail and roller bearing assemblies 2i: and 2 respectively.

The vcentralshaft I49 also carries an overrunning 'roller clutch I5I, through which a multiple disc brake I52 is driven. This brake I52 holds the landing gear (not shown) in the retracted position,'or in any intermediate position the landing gear, a gear train connecting said motors with said landing gear, braking means for retarding movement of the landing gear in one direction only, said braking means including friction elements rotatable about said landing gear axis and uni-directional clutch means interposed between said gear train and rotatable friction elements to render said friction elements effective as a braking means in said one direction of move ment of the landing gear.

2. Landing gear operating mechanism comprising a pair of electric motors disposed in parallel alignment on either side of the axis of rotation of the landing gear, a gear train connecting said motors with said landing gear, braking means for retarding movement of the landing gear in one direction only, said braking means including friction elements rotatable about said landing gear axis and uni-directional clutch means interposed between said gear train and rotatable friction elements to render said friction elements eflective as a braking means in said one direction of movement of the landing gear, means for energizing each electric motor, and means for holding one electric motor drivably disconnected from said gear train when only the other motor is energized.

3. Landing gear operating mechanism comprising a cylindrical housing, actuating means supported at one end of said housing and adapted to be connected to a landing gear, a driving unit mounted in the other end of said housing, said unit including an electric motor, power output means and a clutch interposed between said motor and said power output means, means including a solenoid surrounding said clutch for operating the latter, and means for facilitating operation of said clutch by said solenoid, the lastnamed means including a ball-containing cage surrounded by said clutch, the balls of said cage serving as the torque transmitting means between said motor and clutch.

4. Operating mechanism for a landing gear which tends to move in one direction, comprising a pair of electric motors disposed in parallel alignment on either side of the axis of rotation of the landing gear, a gear train connecting said motors with said landing gear, braking means for retarding movement of the landing. gear in said direction only, means for individually energizing each electric motor, and means controlled by the stated energization to hold each of said motors drivably connected and disconnected from said gear train when the respective motor is respectively energized and de-energized.

5. In combination, a clutch pack having a first set of annular plates with toothed outer edges and a second set of annular plates with their inner edges toothed, an outer driving sleeve, an inner sleeve concentrically loosely fitting inside of the outer sleeve and having its interior splined to slidably fit the toothed outer edges of the first set of clutch plates, a shaft member having its exterior splined to slidably fit the toothed inner edges of the second set of clutch plates, a first anti-friction bearing means for rotatably connecting one end of the outer sleeve with the shaft member to maintain fixed their endwise relation while their permitting relative rotation, a plurality of torque transmitting means operatively connecting the other end of the outer sleeve with the inner sleeve to alter their endwise relation upon a change of their angular relation, 9. first thrust plate for the end of the clutch pack located nearest the first-named end of the outer sleeve and axially fixed on the shaft member, a second thrust plate for the other end of the clutch pack and axially movable with the inner sleeve, a third thrust plate concentric withthe shaft member, a plurality of thrust springs located between the second and third thrust plates to tend to continuously exert a biasing force on the clutch pack, and a second anti-friction bearing means located near the other end of the outer sleeve to rotatably connect the shaft member with the third thrust plate to maintain fixed their endwise relation while permitting their relative rotation; the

arrangement being such that, upon a tendency for the transmitted torque to increase beyond a limit determined by the strength of the springs and the coefllcient of friction of the clutch plates, a relative angular movement followed by the torque transmitting means occurs to move the inner sleeve axially relative to the outer sleeve, to movethe second thrust plate away from the first thrust plate against the bias of the springs to reduce the thrust onthe clutch pack, and hence to maintain the transmitted torque substantially constant.

6. In an operating mechanism for a device which is affected by a biasing load tending to move it in one direction, the combination of a low-speed shaft for driving the device, unidirectional braking means tending to retain the lowspeed shaft in its last-set position in spite of the load, a plurality of power units each having a high-speed shaft parallel with the low-speed shaft and at the same radial distance therefrom, and reduction gearing connecting each highspeed shaft with the low-speed shaft; each power unit including the following, located in line in the following order, an electric motor, planetary reduction gearing driven by the motor, a clutch pack driven by the last named gearing, a torque limiting means for the clutch pack, and a jaw clutch with its respective jaws operatively connected with the output of the clutch pack and the high-speed shaft; each power unit also including a spring means for biasing the jaw clutch toward disengagement, and a solenoid for operating the jaw clutch against the spring bias to engage the clutch when the electric motor is energized.

ROMEO M. NARDONE.

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

UNITED STATES PATENTS Number Name Date 2,284,353 Allen May 26, 1942 2,137,721 Jones Nov. 22, 1938 678,228 Cormier July 9, 1901 723,333 Story Mar. 24, 1903 1,270,533 Lombard June 25, 1918 2,295,289 Nardone Sept. 8, 1942 1,833,948 Lansing Dec. 1, 1931 2,315,110 Dornier Mar. 30, 1943 1,632,539 Chilton June 14, 1927 1,555,098 Benko Sept. 29, 1925 2,180,599 Menasco Nov. 21, 1939 2,262,330 MacNeil et al. Nov. 11, 1941 2,367,076 Varblow Jan. 9, 1945 1,533,655 Merrill Apr. 14, 1925 2,267,114 Lear et a1. Dec. 23, 1941 FOREIGN PATENTS Number Country Date 430,562 Germany 1926

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