A DAMPENING FORK OR STRUT FOR MOTORBICYCLES OR MOTORCYCLES

Abstract: The dampening fork consists in at least two rods (1, 8) telescopically sliding inside a double tubular element (2) provided with respective chambers (25, 28) having an axis on one and the same longitudinal vertical plane; one of the two chambers (25) is filled up with oil pushed by a piston (21), while the other chamber (28) is provided with a piston (39) acting on the air-oil mixture flowing through opening (26) controlled by an adjustable shutter (29) connected to a one-way valve (33). A spring (14) is inserted inside the first rod in the upper part thereof, while another rod (38) is inserted in the lower part of chamber (28) containing the air-oil mixture.

Description: 'A DAMPENING FORK OR STRUT FOR MOTORBICYCLES OR MOTORCYCLES" The present invention concerns a dampening fork or strut for motorbicycles or motorcycles, i.e. a new kind of front or back fork, in this last case also a single central strut that may be applied to motorbicycles or to motorcycles, in particu¬ lar also to the "outboard" kind. The prior art known until now comprises forks and struts for motorcycles with a single rod, each rod being internally pro¬ vided with a spring that sownwardly pushes a piston provided with small passing-through holes for the dripping of the " oil contained in the lower part of said fork or strut: this for dampening the impacts. Furthermore, in this case-of single rod forks and struts, dan¬ gerous twistings may not be prevented, in particular in those cases in which ery long forks or struts are used ' , and fur- thermore annoying and damaging vibrations, in particular of the forecarriage. In the past, an arcuated cross member was used for limiting the twisting in the forks, placed immediately above the sur- face of the tyre of the wheel: such a cross member is howe¬ ver subject to dangerous inconveniences like mud or other elements, such as to block the wheel. These inconveniences may be avoided, eliminating the cross member and greatly reducing the twistings and the vibrations. It is therefore the aim of the present invention to reali- ze a fork or a strut that doesn't twist, that doesn't cause dangerous and annoying vibrations and that, furthermore, im¬ proves the dampening effect and prevents the "dive" or sink¬ ing effect in case of a sharp braking. The aim set forth is reached, according to the present in¬ vention, making use, instead of one single rod, of two rods having the axis thereof placed on a longitudinal vertical plane,i.e. aligned in the driving direction: in the case of a fork, there will be four rods; of the two longitudinally aligned rods, one compresses the oil by means of *a piston, the other one is provided with another piston acting on the mixture consisting of the air contained in the respective chamber and of the oil flowing through a valve. The advantages obtained by means of the present invention are the following: the elimination, or a strong reduction of the possibility of twisting; the elimination or strong reduction of the vibrations; reduction of the sinking; and a greater safety againts those deformations which in any case cause lack of balance. Some embodiments of the present invention are shown in the enclosed drawings, in which: Figure 1, shows a front view of the front fork; figure 2, shows a lateral view in partial section of the fork according to figure 1; figure 3, shows an enlarged sectioned detail of figure 2 for putting into evidence the lower part of a branch of the fork; figure 4, shows a section like the one of figure 3, rela¬ ting to a variant in which one of the two align¬ ed rods has a smaller diameter; figure 5, shows a plant view, enlarged and partially sec¬ tioned, of figure 1; figure 6, shows a lateral scheme of a motorcycle with the fork according to the present invention frontal- ly applied, while at the back there is applied • a couple of lateral dampers of the kind of those shown in longitudinal section of figure 7;. figures 8, 9 and 10 are the cross sections respectively: VIII-VIII of a branch of the front fork of figu¬ re 3, IX-IX of the variant of • figure 4 and X-X of the back damper of figure 7. In the figures, 1 shows the couple of front rods of the front fork, said rods being telescopically sliding inside the couple of double lower tubolar elements 2, lowerly ap- plied to the axis of the front wheel, not shown, through the couple of horizontal holes transversally aligned 3 of lower heads 3' of the fork; 4 and 5 show a couple of transversal trapezoidal plates (figure 5), respectively lower and upper, each provided with a couple of front holes 6 for blocking in the same the couple of front rods 1; 7 (figures 2, 5) shows a couple of back holes of said plates for the blocking in the same of the couple of back rods 8; 9 shows a. back central hole in each of said trapezoidal plates 4 and 5 for the fix¬ ing in said holes of the small rod 10 of the steering; 11 - shows the handle bar fixed to the trapezoidal upper plate - by means of clamps 12; 13 shows tangential screws fro the blocking of rods 1 , 8 in the couple of holes rispectively • 5, 7; 14 (figures 2, 3) shows a helical spring inserter in each front rod 1 between the upper plug 14 and " the stop ring 16 keyed towards the upper end of the hollow shaft 17 lowerly provided with a bush 18 for adhering against the bottom 19 of the double tubolar element 2; 20 shows a screw fro blocking the lower end of shaft 17 against said bottom; 21 shows a plug or anular piston for the closing of the low¬ er end of the rod 1 for leading to sliding the shaft 17 in said rod; 22 shows a helical spring coaxial with said shaft 17 inserted between the stop ring 16 and piston 21 so as to avoid recoils during extension; 23 shows a discharge plug " for the oil 24 introduced into the anular chamber 25 compris¬ ed between one rod of double tubolar element 2 and the respec- tive shaft 17; 26 shows a radial opening provided lowerly in into the baffle 27 for separating anular chamber 25 in which each front rod 1 slides and the anular chamber 28 in which slides each back rod 8; 29 shows a transversal screw shutter for adjusting the opening degree of radial opening 26; 30 shows an element fixed by means of a screw 31 to the bottom 32 in correspondence with each back rod 8, provided with a transversal hole 32' forming the guide of the shutter 29; 33 shows the body of a one-way valve with three diameters: the greatest, and lowermost, . the one coupled to the sliding in the anular chamber 28, provided with vertical holes 34 fo the oil passage, the smallest, in medium position, for the housing of a helical lower coaxial spring 35 that pushes. the ring 36 shutting the holes 34, downwardly, and the up- ,per on^ 37, of.a medium diameter, that forms a rest for the lower helical spring 35 and for the upper helical spring 38 resting in turn, at the opposite end, against the anular closing plug or piston 39 of the lower end of-each back rod 8; 40 shows a shaft inserted into chamber 28, led to sliding in the.hole of anular plug 39, lowerly fixed to the upper part of the valve body 33; 41 shows a protection casing or bel¬ lows having a double holing for the passage, through the sa¬ me, of rods 1, 8, provided at the upper end of double tubo¬ lar element 2;42 shows a little radial conical hole provided in baffle 27 for the quick flowing of the oil 24 from anular chamber 28 to anular chamber 25; 43 (figure 4) shows a couple of back rods, in a variant from the couple of back rods 8 of precedent figures, inserted into the couples of chambers 28 having the function of damping anti-plunge due to the oil 24 passing from chamber 25 to chamber 28 through the radial ho- le .26 of baffle 27 when the springing action starts; 44 shows a vertical hole provided on the bottom of chamber 28 to make interconnected radial hole 46 in which shutter 29 slides with holes 34 of the valve body 33 having a function similar to the one of figure 3; 47 shows (figure 7) the lower ear for the connection of the double back damper, to be mounted fore- wards bent, on both sides or centrally with respect to fork 48 (figure 6) of the motorcycle; 49 shows the lower head of the fork from which two shafts part: the anti-twisting stiaft and the anti-pfunge shaft 50 - smaller - provided with a pi- ston 51, the upper end thereof being sealingly sliding in - Internal chamber 52 of rod 53, upwardly being out of one pie¬ ce with the upper head 54 of said damper; 55 shows a second anti-twisting shaft provided on the same longitudinal plane like the first one and of greater diameter, provided with a piston 57 sealingly sliding in chamber 57 of rod 58 having a greater diameter that rod 53; 59 shows a transversal hole provided in the upper hear 54 fro making chambers 52, " 57 in¬ tercommunicating by means of shutter 60 for adjusting the inlet light in said hole, this all passing through a valve 61 similar to valves 33, 34, 35, 36, 37; 62 shows a small ra¬ dial and conical hole of head 54 for making ϊntercommunicat- ing, upstream of valve 61, chambers 52, 57; 63 shows a heli¬ cal spring inserted between the lower head 49 and the adju¬ stable ring 64 coaxially to rod 58, for the initial dampen¬ ing; 65 shows a couple of superior marginal notches of ring 64, in which the ends of a transversal stop pin 66 will pe¬ netrate; 67 shows the oil contained. in chamber 57 in. resting, condition; 68 shows elastic stop buffers adherent to shafts 50, 55 in the lower part thereof; 69 and 70 show aπular-plugs for the sealing and leading of respectively shafts 50, 57; 71 shows an ear of the upper head 54 for the connection to frame 72 of the motorcycle. The working takes place as follows: in the case of figure 3, at the beginning of the braking action and/or of the meeting with an obstacle on the road or Out of the road, the mass of the total motorcycle/rider(s) weighs on the front wheel caus¬ ing the compression of spring 14 with a following downflow of oil 24 from chamber 25 to chamber 28 through hole 26 and valve 33, beyond the compression of spring 38: such a down- flow and such compression slow down the falling of the hand¬ le bar, comfortably dampening the effect of the braking and/ or of the obstacle. In the case of figure 5 shaft 43 compressing the air-oil mixture in chamber 28, causes a more energical dampening action than the one obtained by means of spring 38 of figure 3. In the case of the back damper of figure 7, both shafts 50, 55 stand the lowering of the back part of the motorcy¬ cle by means of the oil 67 of chamber 57 that flows into chamber 52 through hole 59 and valve 61: spring 63 acts in particular in the first part of the lowering due to the weight of the motorcycle and of the rider with a balancing action of the trim. In an eventual variant, instead of the sole strong spring 63 relating to shaft 55 of the back damper (figure 7), two smaller springs could be used: one still aroung shaft 55, the other one aroung shaft 50.

Claims: C L A I S 1. A dampening fork or strut for motorbicycles or motorcycles, comprising a piston compressing oil flowing in another cham- ber through a hole with a one-way valve and a recoil hole of smaller section, and this due to the variation of powers due to a braking or an obstacle, and also comprising a spring " limiting the sinking, characterized in that said fork or strut consist of at least two rods telescopically sliding in a double tubolar element, having thair axis on one and the same longitudinal vertical plane, i.e. aligned in the runn¬ ing direction: in the case of a front fork, as a couple of double rods is provided, and in the case of a back, bilate¬ ral or central strut, as two rods are present; however one of the two longitudinal aligned chambers is partially fill¬ ed with the oil pushed by a piston, while the other one is provided, with.a. piston acting onto the mixture of the air . however contained in said chamber and of the oil dripping through a one-way valve placed between the two chambers of said double tubolar element, having one end ending up in the common head of said element, and the oil flowing back into the origin chamber through a radial hole of the transversal baffle of sa.id element separating them. 2. A fork according to claim 1, characterized in.that the two . rods (1, 8) aligned on the longitudinal vertical plane and upwardly fixed to the trapezoidal transversal plates (4, 5) interconnected by means of small rod (10) of the steering, are telescopically sliding in the two chambers (25, 28) with axis' similarly aligned, of a double tubolar element (2) upwardly protected by a casing (44) and lowerly provided with a head (3') with ears having a transversal hole (3) for the connection with the axis of the front wheel. 3. A fork according to claim 2, characterized in that e.g. in the front rod (1), telescopically sliding in chamber (25) containing the oil of the double-tubolar element (2) and lowerly provided with a plug or anular piston (21), a heli¬ cal spring (14) is axially inserted between the upper clos¬ ing plug (15) and the stop ring (16) keyed towards the upper end of the internal coaxial shaft (17) lowerly provided with a bush (18) for adhering, once keyed, to the bottom (19) of the head (3 1 ) of the double tubolar element (2): another helical spring (22) is inserted between said anular piston (21) and said stop ring (16). 4. A fork according to claims 1 and 2, characterized in that e.g. the back rod (8), telescopically sliding in chamber (28) containing air, of the double tubolar element (2), is lowerly provided with a plug or anular piston (39) sliding- ly connected on shaft (40) fixed to the upper part of the > body (33) of the one-way valve inserted towards the bottom (32) of chamber (28) above shutter (29) for the adjusting of the light flowing out of the radial opening (26) prov- H ided in baffle (27) of the double tubolar element (2) se¬ parating the two chambers (25, 28); a helical spring (38) is inserted in chamber (28) in which said rod (8) slides coaxially to said shaft, being compressed between said a- nular piston (39) and the upper part (37) of said one-way valve. 5. A fork according to claims 1 and 2, characterized in that said rod being e.g. frontal and telescopically sliding in chamber (25) containing the oil of the double tubolar ele¬ ment (2) lowerly provided with a plug or anular piston (21), and having a helical spring (14) being inserted between the upper closing plug (16) and the stop ring (16) keyed towards the upper end of the internal coaxial shaft (17) lowerly provided with a bus (18) for adhering, once keyed, to the bottom (19).of the head (3!)-.of the double tubolar element - (2), " with another helical spring (22) being- inserted bet¬ ween said anular piston (21) and said stop ring (16), the other rod (43) is telescopically sliding in the other cham- ber (28) of the double tubolar element (2), eventually hav¬ ing a smaller diameter, provided towards the bottom (45) and above the shutter (29), with an adjusting of the light flowing from the radial opening (26) provided in baffle (27) of said element separating the two chambers (25, 28), of one-way valve (33). 6. A strut, according to claim 1, characterized in that inside the two rods (53, 58) of equal or different diameter and a- ligned on the longitudinal vertical plane, having their o- rigin in a common head (54) provided with ears (71) for the connection to the frame of the vehicle or motorvehicle and closed at the opposite side, are telescopically sliding ' ly coupled in the respective chambers (52, 57), one of which (57) is filled up with oil, the respective pistons (51, 56) fixed to the end of the respective shafts (50, 55), having their origin in the common head (59) of said strut, provid¬ ed with an ear (47) for the opposite connection with the frame; a helical spring (63) is inserted between said com¬ mon head of the shafts, outwardly to one or both of said • rods, between said head and ad adjustable ring (64) outward- ly coaxial ' to the respecti e ' rod; a one-way valve-(61) is inserted in chamber (52) containing air towards the head (54) common to the two rods downstream of the adjustable shutter (60) of the radial " hole (59) that makes said cham¬ ber intercommunicating with said oil chamber (57).

Inventors: NEGRINI MAURO, NEGRINI, MAURO
Applicants: NEGRINI MOTO SPA, NEGRINI MOTO S.P.A.
Application year: 1987
Main classification: B62K21
IPC codes: B62K25, F16F9