WHEEL SUSPENSION FOR A WHEEL DRIVEN BY AN ENDLESS TRANSMISSION

Abstract: Wheel suspension for a wheel driven by an endless transmission, characterized in that the rocking point (11), apart from the driven wheel (2), of the rocking arms (9-10) by means of levers (13-15), (28-29) are connected with respect to a part of the vehicle of which the driven wheel is a part, these levers ensuring that during the rocking of the levers (9-10) aforementioned rocking point (11) is always located on an axis drawn through shafts (7-11-3) of the transmission (6-5-4), in which the distance between shafts (3) and (7) is constant or virtually constant.

Description: Wheel suspension for a wheel driven by an endless transmission. Present invention concerns a wheel suspension for a wheel driven by an endless transmission of, for instance, a motorcycle, a trike, a quad, a snowmobile or similar, in which a wheel, more particularly a wheel driven by means of an endless transmission such as a chain, a belt or similar cooperates with sprocket wheels or pulleys, on the one hand, on a crankcase, frame, chassis or similar and, on the other hand, on aforementioned driven wheel. It is known that an aforementioned driven wheel is generally mounted on a rocking arm whose second extremity is hinged with respect to the frame, in which this hinged attachment usually is provided between aforementioned sprocket wheels or pulleys. It is known, among others, that such an arrangement results, due to the rocking of the rocking arm, caused by irregularities in the road surface with which the driven wheel is in contact, in continuous variations in the tension of the endless transmission. The variance in distance between the pivoting point of the sprocket wheel at the motor's end and the hinge point of the rocking arm at the motor's end together with continuous tension variations in the endless transmission during the rocking of the rocking arm result herewith in the fact that during acceleration or braking of the driven wheel an unwanted force is applied to the rocking arm which forces latter to spring in or spring out, depending on the accelaration or braking applied. Present invention thus concerns a suspension in which one endeavours to keep aforementioned force as small as possible, respectively eliminate it, on the one hand, and to keep aforementioned tension as constant as possible, on the other hand. A suspension according to the invention consists mainly in that the rocking point of the rocking arm distant from the driven wheel is connected with respect to the crankcase by means of levers, in which these levers provide, during the rocking of the levers, for aforementioned rocking point always to be located on a line drawn through the axles of the endless transmission, in which the distance between these axles always remains constant or nearly is constant. An embodiment is known, as described in US 4.058.181, in which a suspension is provided for the rear wheel of a motorcycle formed by a pure parallelogram system. The disadvantage of such a system is that it is not only formed by a relatively high number of parts and pivoting points, but as well that the mass of the whole becomes quite substantial which is detrimental to the suspension's inertia. In order to cope with the disadvantages related to such an embodiment according to US 4.058.181, US 4.408.674 suggests an embodiment which aims at reducing the inertia of the suspension. The disadvantage of latter embodiment, though, is that the number of parts, on the one hand, and the number of pivoting points, on the other hand, increases substantially these pivoting points being quite difficult to protect against water, dirt, sand and similar in such way that said design is quite susceptible to wear and tear, especially considering that the use of it usually occurs in most adverse conditions. Present -invention thus concerns an embodiment in which a mechanism is applied which is developed with a minimum of pivoting points and a minimum of elements, this, in such way, that the rotating parts to which real forces are applied to can be protected against dirt and similar, on the one hand, and in which a design is applied which only serves the purpose of positioning aforementioned mechanism and which is preferably formed by a parallelogram, on the other hand. The main advantages obtained with a suspension according to the invention are : a favourable distribution of forces during accelaration and braking; due to this, the possibility of good accelerations; no jerkey drive of the driven wheel; increased elasticity; a simple frame; the possibility of installing a brake on the output shaft of the crankcase instead of on the driven wheel. In order to better show the characteristics of the invention some preferential embodiments are described hereafter, as an example and without any restrictive character with reference to the enclosed drawings, in which : - figure 1 shows a schematic side view of a motor¬ cycle on which the rear wheel suspension is applied according to the invention; - figure 2 shows, at a large scale, the part indicated in figure 1 by F2; - figure 3 shows, at a larger scale, the part indicated by F3 in figure 2; - figure 4 shows a similar view to that in figure 2, but for a more practical embodiment; - figure 5 shows a view according to line V-V its figure 4; - figure 6 shows, on a larger scale, the part indicated by F6 in figure 4; - figure 7 shows a view according to line VII-VII in figure 6; - figure 8 shows a view similar to that of figure 4, but for a second position; - figure 9 shows, at a larger scale, the part indicated by F9 in figure 8; - figure 10 shows a schematic view of the movement of the point of suspension of the rocking arm from which the driven wheel is suspended, in a part rigidly affixed to the frame, for the embodiment according to figure 2; - figure 11 shows a schematic view of the movement of the point of suspension of the rocking arm from which the driven wheel is suspended, in a part rigidly affixed to the frame, for the embodiment according to figure 4; - figure 12 shows, at a larger scale, a further developed embodiment of figure 7; - figure 13 shows a cross section according to line XIII-XIII in figure 12. The following description will include, as an example of an endless transmission, the description of a so-called sprocket wheel transmission. In figure 1, a motor 1 is shown to which the driven wheel 2, according to the invention, is suspended. A sprocket wheel 4, which by means of chain 5 cooperates * -*- ■ continuously with a sprocket wheel 6 which is mounted on the output shaft 7 of the crankcase 8, is mounted to the driven wheel 2. According to the invention the shaft 3 mounted in the rocking arms, respectively 9 and 10, which are 0 hinged with their second extremity on a common shaft 11 which in turn is mounted on the crankcase 8. Preferably, the rocking arms 9 and 10 are joint together by a bridge connection 12 (see figure 5) between the crankcase 8 and the driven wheel 2. On at least one extremity of shaft 11, in the embodiment according to figure 2, a freely rotating lever 13 is mounted, whose free extremity is hinged freely, by means of a pivot 14, with a second lever 15 which is supported on bearings, by means of a pivot or shaft 16, in the crankcase 8 on an appropriate location. On shaft 11, furthermore, a rod 17 is. installed, freely rotating, on whose second extremity, by means of a freely rotating shaft 18, linked to a rod 19 which, at one extremity, is connected by means of a pivot 20 and a support 21, in this case, with the crankcase 8 and whose second extremity, by means of a pivot 22 is connected, freely rotating, with a rod 23 whose second extremity, by means of a pivot 24, is connected with an extension 25 of, in this case, the rocking arm 9. The distances between shafts 7 and 20, between shafts 11 and 18 and between shafts 22 and 24 are equal to one another while, on the one hand, the axis drawn through the shafts 7-11-3-24 and 20-18-22 and, on the other hand, the axis drawn through shafts 7-20, 11-18 and 24-22, are respectively parallel to each other in order that a pure parallelogram system is obtained which, in this case, is only used as positioning means for the lever mechanism. Arms 9 and 10 are sprung with respect to the frame 26 by a suspension construction with a built in shock absorber 27. According to the embodiment as shown in figures 2 and 3, whenever the driven wheel 2 encounters irregulari¬ ties, latter will move up and down and attempting to rock around shaft 7. In this case the tension on the chain 5 remains virtually constant due to the presence of, among others, the levers 13 and 15, with the aim to maintain the distance between shafts 3 and 7 constant or virtually constant. Indeed, the levers 13 and 15 are ensuring that, as shown in figure 10, the shaft 11 virtually describes a circular track with shaft 7 as centrepoint. Figures 4 through 9 inclusive show a more practical embodiment of a wheel suspension according to the invention. In this case all parts can be found as described in figure 2, in which the levers 13 and 15 are, in this case, integrated in two cylindrical discs, respectively 28 and 29. Disc 29, according to the invention, is supported by bearings to allow free rotating movement in an extension of crankcase 8, while disc 28 is supported by bearings, in an eccentric manner, to allow free rotating movement, in disc 29. The eccentricity E of disc 28 with respect to disc 29 is equal to the length El of lever 15. In disc 28, shaft 11 of. the rocking arms 9-10 is mounted, which arms are mounted freely rotating onto shaft 11, in which this shaft 11 is placed eccentrically in disc 28 with an eccentricity E2 which is equal 10 to length E3 of aforementioned lever 13. As shown in the drawings, in order to ensure maximum stability, two discs 28 and two discs 29 are provided for. It is evident that in this embodiment, and as better 15 shown still in figure 11, while the levers 9-10 rock a rotation of discs 28 in the respective discs 29 is obtained which themselves are provided in a rotating manner in crankcase 8, in such way that shaft 11 moves back and forth in a virtually circular track 20 the centrepoint of which coincides with the axis of shaft 7. It is noted that, according to the invention, a construc¬ tion or mechanism is obtained in which the rocking arms (9-10) absorb all forces, while the rods (17- ~ ~ 19-23) virtually do not absorb any forces, but only serve as positioning means and can consequently be kept rather light. It is evident that, in this manner, a wheel suspension, for instance, for a motorcycle is achieved which 30 excludes a tensioning device and which, not only, is very simple in construction, but can as well be realized with a minimum number of parts which are only intended to control movement, but do hardly transfer any forces in such way that the mass thereof can remain quite small and that the inertia of the suspension device is not being adversely affected. Moreover, the various pivoting points, the present mutual rotations of the discs 28 and 29 can be sealed in a very elementary manner, in other words be protected agains water, mud, dust and similar, in which their wear and tear can be limited to a minimum. Figures 12 and 13 show another embodiment in which means are provided which allow for synchronizing discs 28 with respect to discs 29. For this purpose, discs 28 are mutually connected by a connection piece 30. Latter shows a passage 31 for the rod 17 which is mounted, freely rotating, on shaft 11. Part 30 is, in this case, provided with protuberances 32-33 between which, by means of spindles 34-35, a tubular guide 36 for the guide rod 37 is hinged. This rod 37 is mounted in the housing 8. This arrangement allows for both discs 28 and both discs 29 to always move jointly. It is clear that aforementioned arrangement is not li itative and that it can -be replaced by other embodiments which provide for the same result. Discs 29 are linked to one another by means of a rod or bracket 38 in order to always make these discs 29 move jointly. Other variants are also possible. In this way the location of rods 17 and 23 can be different of that represented in the examples; more or less rods than rods 17 and 23 can be applied; the extremity of rod 19 can be connected to the frame 26 in lieu of crank¬ case 8; rod 19 can be located, in lieu of above the rocking arms 9—10, next to or underneath these rocking arms 9-10 or be integrated in the rocking arm 9-10; rod 19 can be located as well outside of as in the crankcase; etc. Present invention is obviously in no way restricted to the embodiments described as examples and shown in the enclosed drawings.

Claims: Claims . 1.- Wheel suspension for a wheel driven by an endless transmission, characerized in that the rocking point (11) , apart from the driven wheel (2) , of the rocking ~ arms (9-10) by means of levers (13-15), (28-29) are connected with respect to a part of the vehicle of which the driven wheel is a part, these levers ensuring that during the rocking of the levers (9-10) aforemen¬ tioned rocking point (11) always is located on an 10 axis drawn through shafts (7-11-3) of the transmission (6-5-4), in which the distance between shafts 3 and 7 is constant or virtually constant. 2.- Wheel suspension for a wheel driven by an endless transmission according to claim 1, characterized - ~ in that the rocking point (11), apart from the driven wheel (2), of the rocking arms (9-10) by means of levers (13-15), (28-29) are connected with respect to the crankcase, in wh ch these levers ensure that during the rocking of the levers (9-10) aforementioned 20 rocking point (11) always is located on an axis drawn through shafts (7-11-3) of the transmission (6-5-4), in which the distance between shafts 3 and 7 is constant or virtually constant. 3.- Wheel suspension for a wheel driven by and endless ~ ~ transmission according to claim 1, characterized in that the rocking point (11) , apart from the driven wheel (2), of the rocking arms (9-10) by means of levers (13-15), (28-29) are connected with respect to the vehicle frame, in which these levers ensure 30 that during the rocking of the levers (9-10) aforemen¬ tioned rocking point (11) is always located on an axis drawn through shafts (7-11-3) of the transmission (6-5-4), in which the distance between shafts 3 and 7 is constant or virtually constant. 4.- Wheel suspension for a wheel driven by an endless transmission according to one of the claims 1,2 or 3, characterized in that the levers (13-15) are hinged freely and connected, in which the second extremity of a lever (13) is hinged with the front hinged link (11) of the rocking arms (9-10), while the second extremity of the second lever (15) is hinged freely with respect to the crankcase (8). 5.- Wheel suspension for a wheel driven by an endless transmission according to one of the claims 1, 2 or 3, characterized in that the levers are formed by discs (28-29), of which disc (29) is freely supported by bearings with respect to the crankcase (8), disc (28) being placed eccentrically and rotating with respect to disc (29) and the front hinge shaft (11) of the rocking arms (9-10) being placed eccentrically in disc (28 ) . 6.- Wheel suspension for a wheel driven by an endless transmission according to one of aforementioned claims, characterized in that discs (28), respectively discs (29), are connected in pairs, respectively by means of a connection piece (30) and a rod or bracket (38). 1. - Wheel suspension for a wheel driven by an endless transmission according to one of aforementioned claims,characterized in that the rocking arms (9-10) form a part of a parallelogram system formed by the rocking arms (9-10); a rod (19) parallel to these rocking arms and two parallel rods (17-23) which are hinged freely to the extremity of a rocking arm (9-10) and the rod (19), in which latter is extended and is hinged at its extremity with respect to the crankcase (8 ) at a location where the distance to the output shaft (7) is equal to the length between the hinge extremities (11-18) and (24-22) of the shafts (17- 23) and aforementioned levers (13-15), (28-29) being provided, between the front hinge (11) of a rocking arm (9-10) and the crankcase (8). 8.- Wheel suspension for a wheel driven by an endless transmission according to one of aforementioned claims, characterized in that the front hinge (20) of rod (19) is provided with a support (21) on the crankcase (8). 9.- Wheel suspension for a wheel driven by an endless transmission according to one of claims 1 through 7 included, characterized in that the front hinge (20) of rod (19) is provided with a support (21) an the frame of the vehicle. 10.- Wheel suspension for a wheel driven by an endless transmission according to one of aforementioned claims, characterized in that the rear arm (23) of the parallelogram system is hinged to an extension (25) of a rocking arm (9-10). 11.- Wheel suspension for a wheel driven by an endless transmission according to one of aforementioned claims, characterized in that the rod (19) is located above the rocking arm (9-10). 12.- Wheel suspension for a wheel driven by an endless transmission according to one of claims 7 through ιo included, characterized in that rod (19) is located underneath the rocking arm (9-10). - IS ¬ IS.- Wheel suspension for a wheel driven by an endless transmission according to one of claims 7 through 10 included, characterized in that rod (19) is located next to the rocking arm (9-10). 14.- Whesl suspension for a wheel driven by an endless transmission according to one of claims 1 through 10 included, characterized in that rod (19) is integrated in a rocking arm (9-10).

Inventors: VAN DE VEL ALFONS, VAN DE VEL, ALFONS
Applicants: VEL ALFONS VAN DE, VAN DE VEL, ALFONS
Application year: 1989
Main classification: B62K25
IPC codes: B62K25