US 2605734 A
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Description (OCR text may contain errors)
Aug 5, 1952 l.. D. wA'rKlNs 2,605,734
VIBR-ATION ABSORBING MOUNTING FOR OUTTBOARD MOTORS Filed Jan. 5, 1949 llllnlllll/l ac/v D. WHK//v Cttornegs .showing the pistons, `connecting rods,
Patented Aug. 5, 1952 man ,FFME
VIBRATIN ABSRBING MOUNTING FOR OUTBOARD MTORS Lucius D. Watkins, Milwaukee, Wis., assignor to Outboard, Marine & Manufactm-ingompany, Waukegan, Ill., a corporation of Delaware Application January 5, 1949, serial No. 69,315
This invention relates to vibration 'absorbing linountings for outboard motors.
It is the primary object of the invention to provide novel and improved means oilering variable damping resistance to the various forms of vibration to which an outboard motor is subject, the damping means offering materially greater resistance to vibration in some planes` than to vibration in other planes and, in addition, offering a resistance which varies according to the intenlsity'of the vibration. rlhe mannerin which .these objectives are achieved will lbemore particularly explained 'in connection with the following disclosure ofthe invention.
' -In thevdrawings Fig. ly is a view-in side elevationl of anout- 'board motor embodying the invention, thisbeing -a somewhat diagrammatic or phantom view crank shaft, flywheel, drive shaft and propeller shaft of lthe outboard motor in dotted lines. Fig. -2 is an enlarged fragmentary detailiview -in'longitudinal axial section taken on line 2..2 vof Fig.. 4 through the Aintermediate portions of the outboard-motor 4andV its mounting bracket.
Fig. 3 is a view taken in section on line 3-3 billig. 2. I
YFig.` 4 is a View taken' in section on line -fi Aof Fig. 2.
.-Fig. 5 -is a view taken in-section` on line-'545 cflFig. 2
Fig. 6 is a detail `view in :perspective showing fone `of the double` cushioning .elements as .de sirably used in practice of v.the invention. v
As Vis usual, the voutboard motor comprissv.;a transom bracket 2S and 'a shaft housing 9,.; the shaft housing-carrying at its upper end th'erprime mover lo y'and -at tsflower end a gear housing -l.|. The fprime moverl drives .the vertical. shaft ulf2 whichV extends downwardly vthrough .housing "9 to-housing l-I for actuating the propeller 13.
The "transom bracket 8, whichis clamped-to the transom of the boatV to bepropelle'd, .is .provided, in accordance with conventional practice, lwith atransverse'pintle at lftupon which'there is .,pi-votallycarrieda sleevel within which.;the entire assembly. of :the ,powerV head l0, .ashaft housing .9, the lower lunit '.ll :and propeller lf3 f1.7; claims. (o1. 11s- 18) l ving application Serial No. 13,036, filed March 4,
19.43kr and entitled Outboard Motor Thrust and Tilt Lock Adjustments now U. S. Patent No. 2,583,910 dated January 29, 1952. There is a bushing ,at .26, desirably made of rubber, interposed between the shaft housing 9 and the sleeve i5' near the lower end of this sleeve. yThe pro,- peller thrust developed by the rotation of the .propeller I3 is communicated tothe gear housing or lower unit .I I and thence to the shaft housing Sand'thence through the bushing 20 to the sleeve i5 and thence via member I6 and element Il to the bracket 8 and the transom of the boat. Since the thrust transmission to the thrust receiving element il occurs at a level materially above the level of the .propeller I3, a thrust moment is developed, tending to pivot the. entire dirigible assembly about the yhorizontal transverse axis represented bythe thrust receiving element il.
Thus there is Aa tendency for the upper end of thek shaft housing to move rearwardly under -thrustof -thepropellen this tendency being resisted in the manner hereinafter explained.
Rotativelyy fitted within the upper end ofthe `sleeve i5 isa sleeve 2| with which there is rigidly connected a yoke 22 (Fig. 4) which may integrally provide a steering handle 23 and to which the p tiller 2d is connected. Where the yoke attaches `to the inner sleeve 2i, there is formed an enlarged chamber 25 (Fig. 4) having a relatively small forward pocket at 26 and a relatively larger rear pocket 2l in which there are rubber cushions at 28 and 29, respectively (Figs. 2 and 4). Each of these cushions may extend substantially rectilinearly at its inner margin to receive the sleeve 30 Yinto which the upper end'of the shaft housing 9 is braced or otherwise fastened. The sleeve 38 serves as a means of mounting the power head le on the upper end of 'the shaft housing.
It will be observed that the sleeve 30 is materialjly smaller` diameter than the interior vare swiveled on avertic'alaxis'for steering.. ilhe Y -uprightposition of sleeve f l5 and the assemblyl di-ameterLofsleeve 2 l, so tha-t there is substantial clearance between these sleeves as best shown in Fig. 2. Thus, the shaft housing and power head are f-ree to move fore'and aft, laterally, and torsionallyrespecting the tiller-connected sleeve 2l and the sleeve. I5 in which the tiller-connected sleeve 2l is'rotatable. The rubber ,cushions at :2B .and v29 are desirably made to absorbfore 'and aft thrust only, `and to damp .fore land aft vibration only. :Because of the -tendency of the dirigibleassembly tovpivot about the thrust element Il in response to the thrust of the propeller I3', thereby tending to move the upperendof -the shaft housing 9 rearwardly, as above pointed out, the cushion 29 is made very materially larger than cushion 28, cushion 28 having relatively little thrust exerted upon it. The reason why, in this preferred embodiment of the invention, the cushions 2-8 and 29 absorb longitudinal fore and aft thrust only is because their surfaces with which sleeve 30 is engaged are, in this exemplification, substantially rectilinear transversely of the device, as clearly appears in Fig. 4. So far as these cushions are concerned, the sleeve 30 and shaft housing 9 can move laterally with complete freedom to the limit permitted by the enclosing sleeve 2 I.
According to the design of the power head I0, assuming this to be an internal combustion engine, the movement of the pistons and connecting rods will set up vibration which may be either in ia fore and aft direction or in a transverse direction. The reason why it is preferred that the -cushions 28 or 29 act in a fore and aft direction only is because, by separating the fore and after damping means from the later-al damping means, it is possible to select cushions having exactly the desired damping characteristics for the performance of the desired damping operation in the particular planes in which respectively they act.
In the present device, the means which damps lateral vibration also damps torsional vibration. Torsional vibration is an important factor in an outboard motor and tends to oscillate the power head shaft housing 'and lower unit to and fro upon a zvertical axis which, desirably, may coincide approximately with the axis of the drive shaft I2. The torque transmitted to the propeller through the drive shaft I2 is generated by well defined impulses, whether the prime mover is an internal combustion engine with reciprocating pistons or whether it is a motor or-turbine. During the power impulses, a reaction equal to the maximum torque is developed in the cylinder or other frame of the prime mover. During vthe interval between such impulses, there is a tendency for the fly wheel effect of the shaft and associated parts to communicate torque in an opposite direction to the cylinder or other frame of the prime mover. Thus the entire prime mover and the shaft housing 9 and lower unit II tend to oscillate as a unit about ra vertical axis as aforesaid.
Such oscillation can best be resisted and damped by cushions which are radially remote from the axis upon which oscillation occurs. If, as in thewinsltant device, the cushions are also used to resist anduto dampv lateral vibration of the assembly within the bearing, these cushions `should b e disposed at opposite sides of a fore and iaft plane'.- A l W-ith the foregoing objectives in View, I provide pairs of cushions respectively shown at 33, 34 and 35, 36, the cushions of each pairV being, for convenience, but not necessarily, connected together as a unit by a thin web 31 of the material of which the cushions are formed. l
The external shape of the cushio-ns is important. Each has an end bearing surface 33 whchis materially smaller in area vthan the general cro-ss section of the cushion in an adjacent parallel plane. For thepurpose of exemplifying the invention, the respective cushions areshown as being cylinders having Yends frusto-conically tapered at 39 to the terminal bearing surfaces 38 above described. The opposite ends of theindivdual cushions, here shown as their inner con- 4 tiguous ends, across which the web 31 is connected, may be parallel.
As clearly shown in Figs. 2, 3 and 4, one pair of cushions is located on the longitudinal center line of the outboard motor forwardly of the axis of shaft I2 (or other axis of oscillation), While another pair of cushions is located aft of such axis. Cushions lof the respective pairs are desirably located rat opposite sides of the longitudinal center line.
One of the relatively oscillatable parts of the outboard motor has lan ear confined between the cushions, while the other relatively oscillatable part of the outboard motor has ears engaged externally with the reduced terminal surfaces 38 of the cushions. It so happens that in the particular device illustrated, it is the power head I0 which, on the forward side of the drive shaft I2 isv provided with an ear at 40 engaged between cushions 33 and 34, the yoke 22 having the ears 4I and 42 engaged with the reduced thrust surfaces 38 of cushions 33 and 34 to limit the lateral displacement of the cushions under thrust of the ear 40. It further happens that in this particular exemplication of this invention, the situation is lreversed so far yas the rear set of cushions is concerned. In the rear pair of cushions, it is the yoke V22 which provides the centr-a1 ear at 43, while the power head I0 provides the outside ears 4'4 and 45 as shown in Fig. 4.
Study of Fig. 4 will disclose that bodily lateral displacement ofthe power head I0 in a direction away from the observer will be resisted by cushions 33 and 35 and bodily movement of power head I0 toward the observer will be resisted by cushions 34 and 36. Clockwise oscillation of the power head I0 with respect to the tiller yoke 22 will subject cushions 33 and 35 to compression while counterclockwise oscillation of the power head respecting the tiller head will subject cushions 34 and 36 to compression. The particular cushions which are compressed will, in any given design, depend upon which of the ears confronting the cushions are connected to the respective parts subject to torsional movement.
The importance of having the respective cushions tapered toward terminal bearing surfaces lies in the fact that thereby vthe resistance of the cushion is proportioned to the displacement. In a rapidly operating prime mover, the amplitude of torque vibration, and other vibration, is relatively limited. Under such circumstances, the respective cushions are only slightly compressed and, in the course of slight compression, the surfaces acted upon are of relatively slight area so that the damping resistance is at a minimum.
vWhen the prime mover operates at slower speeds,
the powerimpulses are farther apart and the amplitude of vibration isgreat. Under these conditions, the cushions become more highly cornpressed and, as -they are compressecLtheir tapered portions flatten out so that a greater and greater surface is engaged by that flange or ear against which'the cushion is being compressed. This increases the resistance of the cushion proportionately tothe pressure, the pressure, in turn, increasing proportionately to the amplitude. Thus,:there is relatively great resistance and relatively'great damping effect when vibration tendsto be severe and relatively less resistance and less damping when the vibration is moderate.
vIt `will be apparent that with the device disclosed there'will'be very'little vibration of any :sor-t transmitted-'to the transom bracket and the boat. L Mostof-/th'e fore vand aft vibration is .absorbed in blocksl 28,229. In `any event, theprime mover design will desirably' be such as to mini- -miZeforerand-aft vibration. The lateral vibration yand the torsional vibration will be largely absorbed inthe cushions 33, 34 and 36. Such and consequently the transverse vibration will be absorbed in the sleeve i and the transom bracket. Such torsionalvibration as remains undamped bythe cushions will be transmitted torsionally to the tiller-connected sleeve 2| and-will tendl merely 'to' oscillate's'uch sleeve idly'within the swivelbearing I5.
While I have shown the cushions paired in integral units, it will beunderstood that this is merely preferred practice and isv not essential to the invention. It is also immaterial in a broad sense that I have shown the tapered surfaces of the cushions directed outwardlyrather than inwardly. Except as indicated inl the appended claims, I do not desire to limit the invention to the particular form or disposition of the' cushions f illustrated.
The lcushions used4 are desirably made of natu'- ral or synthetic rubber rather than metalsp'rings, rubber having the greater damping effect. As is well known in the art, the composition of the rubber 'may be -varied to control the resistance offered by the respective cushions according to the pressure to which they( will be subject in use.V VFurther control is possible by changes in size, porosity and shape, according to design requirements.
l. In an outboard motor the combination with a unit comprising power head, shaft housing, and lower unit, and a transom bracket mounting therefor with which said unit is in tiltable relation, of ymounting means between the unit and said bracket mounting'providing for movement therebetween whereby said unit is free to vibrate fore and aft and transversely, a first damping cushion means positioned between the unit and the bracket mounting for lresisting fore and aft vibration, and a second and entirely separate damping cushion means between the unit and the bracket mounting for resisting lateral vibration, said second damping cushion means comprising a cushion forward of the shaft housing and another cushion aft of the shaft housing.
2. The device of claim 1 in which said unit is also subject to torsional vibration upon an upright axis, and one of said cushion means comprises cushions at opposite sides of said axis confined between said unit and said bracket mounting in positions to resist torsional vibration in addition to resistance of the vibration previously mentioned.
3. In an outboard motor, the combination with a transom bracket and a swiveled dirigible unit comprising power head, shaft housing, and gear housing, of a sleeve through which said shaft housing extends in spaced relation to the sleeve, means for transmitting thrust of said shaft housing to said transom bracket, a thrust absorbing cushion aft of the upper end of the shaft housing and having a transverse surface contacting the housing only adjacent its fore and aft center line and resisting only rearward displacement of the said upper end in said sleeve in response tothrust developed at said gear housing.
4.` In an outboard motor, the combination with a support provided with a'swiv'el bearingyof. a dirigible upright unit having a power head at its upper end and a propeller at its lowerv rend,. said unit having means pivoted upon saidf bearing for dirigiblemovement, said bearing including sepa.- rate `lower and upper-.bearing portions, theupper bearingy portion comprising yieldable lcushions having Vwith respect to the upright unit-transversely extending and longitudinally spaced surfaces engaging said member fore and aft and leaving said member relatively7 free for lateral vibra- -tion, said member andsupport having forel: and aftv of said unit'separate mutually engaged means for resisting-lateral vibration.l l
5. The combination set forth in claimv l in which the aft cushion is materially larger than the cushion forward of said member.,`
6. In an outboard motor, the combination with a transom bracket, a tiller member pivotally'mo-V- 'able respecting the transom bracket, anda motor member having a prime mover at its upper end and a propeller at its lower end connected for -unitaryrsteering movement and mounted for osc'illation coaxially with said tiller member, of cushionmeans interposed between said members and comprising a pair of cushions forwardly of said axis, another pair of cushions rearwardly of said faxis,-and vthrust abutments connected with the respective members and between which the cushions of the respective pairs are confined to resist displacement of either member with respect to the other in either direction.
7. In an outboard motor having a transom bracket provided with a thrust element and a vswivel bearing sleeve pivoted ona transverse axis to Vthe transom bracket and provided with a thrust member engageable with said element at a point materially below the said axis, the combination with such sleeve of a tiller member swiveled therein and having portionsgextending forward and aft of said sleeve, amotor member extending loosely through the tiller member and through the swivel bearing sleeve and provided with a cushion positioning it in the latter, the motor member having a prime mover above said transverse axis and a propeller operatively connected with the prime mover and disposed below saidl sleeve, cushions fore and aft of themotor member for yieldably locating it in a fore and aft direction in the tiller member through which it loosely extends, and separate cushions interposed between the motor member and the tiller member both forward and aft of the sleeve and resisting lateral displacement thereof.
8. The device of claim 7 in which said separate cushions are arranged in pairs respectively fore v and aft of the motor member, the respective pairs ,being symmetrically disposed with reference to a longitudinal line drawn fore and aft through the motor member, one of said members having a thrust ange between the cushions of each pair and another member having spaced flanges engaged externally with the cushions of each pair.
9. In an outboard motor for normal forward propulsion, a power unit having a shaft and shaft housing connected to a lower propulsion unit subject to thrust, a bracket and tiller assembly provided with an oversize sleeve for reception of the shaft housing whereby in the operation of the outboard motor the thrust may shift the housing in said sleeve, and oppositely positioned cushions between the sleeve and the shaft housing .having transverse surfaces substantially tangent to the upper end of the shaft housing on its fore and aft center line and free of said housing elsewhere, one of said cushions being smaller thanthe other, the larger cushion being positioned to resist thrust of the propulsion unit in forward propulsion.
10. In an outboard motor for normal forward propulsion, a power unit having a shaft and shaft housing connected to a lower propulsion unit subject to thrust, a bracket and tiller assembly provided With an oversized sleeve for reception of the shaft housing whereby in the operation of the outboard motor the thrust may shift the housing in said sleeve, said tiller having fore and aft cupped receptors for cushions, cushions in said receptors, and the power unit having complementary fore and aft means for engagement with said cushions, said receptors and cushions being spaced from the shaft housing.
11. In an outboard motor a power unit having a shaft and shaft housing connected to alower propulsion unit subject to thrust, a bracket for attachment of the outboard motor to a support and provided with a sleeve-like mounting to loosely receive the shaft housing, a tiller assembly having a tiller sleeve loosely receivable between the shaft housing and said bracket sleeve, the tiller assembly being yoke-shaped about the shaft housing and providing cushion confining means at points spaced from the shaft housing and approximately diametrically opposite one another under the power head, said power unit having portions overlying said cushion confining means and having complementary means for engagement with said cushions whereby to assist in centering the power head and shaft in said bracket sleeve.
12. An outboard motor comprising the combination with an oscillatable unit comprising a power head shaft housing and lower unit, of a mounting therefor in which said unit is free to vibrate fore and aft and transversely, a first damping cushion means resisting fore and aft vibration, said cushion means having thrust receiving contact with said unit substantially only at diametrically opposed points spaced fore and aft, whereby to leave said unit relatively free for transverse vibration, and a second and entirely separate damping cushion means having lateral thrust receiving connection between said mounting and said unit to resist torsional vibration.
13. The device of claim 12 wherein said first and second damping cushion means are substantially aligned fore and aft on the axis of normal fore and aft vibration of the unit.
14.Y rIhe deviceof claim 12 .whereinsaid cushion means resist vibra-tionin compression, the axis of; compression of the first cushion means being transverse to that. ofthe second cushion means.
15,.yThe device of claim 12 wherein saidrst 16. In an outboard -motor, lthe. combination vwith a transom bracketand a swiveled dirigible unit, said transom bracket Ahaving amounting for the dirigible unitand yieldable cushions between said mounting and said unit, said cushions being disposed on thefore andaft axis of unit vibration and having rectilinear cushion surfaces transverse to said'axis -and against which the unit is in fore and aft thrustrelaticnship but is relatively free for. lateral vibration.
17.- The device of claim 16 in further combination with a second vibration damping cushion means comprising yieldable'cushions disposed at points radially oiset from said unit and on opposite sides of said unit along said fore-and aft axis, said unit and mounting being provided with complementary seats, between Which said second cushion` means is disposed .to vabsorb the torque vibration of said unit.
LUCIUS D. WATKINS.
REFERENCES CITED The following references are of record in the file .of this 4patent:V
UNITED STATES PATENTS Italy May 22, 1934