MECHANICAL GEARING

Abstract: The invention relates to a mechanical transmission (1), which transmission (1) comprises guide means for realising a rotational translating movement of a wheel (8) which is connected to an output shaft (7) and which makes contact with an endless belt (10) of mutually abutting push links (14), which guide means are assembled from at least two linear guide tracks received mutually perpendicularly in the same plate and guide elements (73) co-acting with the linear guide tracks, wherein guide elements (73) are connected to the wheel (8) for rotational translation and guide elements (73) are rigidly connected to the frame whereby the plate (85) is movable in linear manner relative to the frame and the wheel (8) is displaceable in linear manner relative to the plate (85).

Description: MECHANICAL GEARING The invention relates to a mechanical transmission comprising a frame, a first shaft which is rotatably connected to the frame and to which is fixed a pair of friction wheels placed at a mutual distance, a second shaft which is connected to the frame for rotation eccentrically parallel to the first shaft and which carries a wheel which co-acts with a belt comprising a circular belt contact surface located axially between the friction wheels of the first shaft, and an endless belt of mutual- ly abutting push links, which belt forms mutually opposite side surfaces which co-act with the pair of friction wheels and of which belt a surface facing radially furthest to the outside forms a surface for co-action with the single wheel co-acting with the belt, wherein the friction wheels comprise mutually facing friction surfaces which converge to the outside. Such a mechanical transmission is described in European patent application no. EP 94.910064.8 in the name of the same applicant as for the present invention. The present invention has for its object to provide improvements and additions to a construction of the type described in the preamble. The invention provides for this purpose a transmission of the type stated in the preamble wherein the transmission comprises guide means for realizing a rotational translating movement of the wheel which is connected to the output shaft and which makes contact with the belt, which guide means are assembled from at least two linear guide tracks received mutually perpendicularly in the same plate and guide elements co-acting with the linear guide tracks, wherein guide elements are connected to the wheel for rotational translation and guide elements are rigidly connected to the frame whereby the plate is movable in linear manner relative to the frame and the wheel is displaceable in linear manner relative to the plate. It is known to use a planetary or differential system, such as for instance a plurality of planetary wheels for driving by a sun wheel and having an eccentric cam fixed to the wheel for rotational translation. A rotational translating movement is understood to mean a rotating movement of the wheel round an axis lying perpendicularly of the wheel and intersecting a plane through the wheel at a distance from the centre of the wheel. The wheel herein does not rotate relative to the centre of the wheel, i.e. the orientation of the wheel does not change during the rotational translating movement. The invention provides a transmission which can be manufactured much more advantageously. The present invention also provides a mechanical transmission of the type stated in the preamble, wherein the transmission comprises adjusting means for adjusting the eccentricity of the wheel connected to the second shaft relative to the first shaft, which adjusting means are formed by a rotatable and fixable eccentric. Such an eccentric which is simple to adjust enables variation in simple manner of the transmission ratio in a range which in principle is infinite, wherein it is also possible to cause the output shaft to stand still or to rotate in a direction opposed to that of the input shaft. The invention moreover provides a mechanical transmission of the type stated in the preamble wherein the friction wheels are supported externally by axially displaceable nuts, which nuts are provided with contact surfaces which co-act with contra-contact surfaces arranged close to the external edge of the friction wheels. The contact surfaces and contra-contact surfaces preferably form parts of a helix. Even more preferably the nuts are placed under a bias in a direction toward each other, whereby the belt can be clamped with a predetermined force between the friction wheels, whereby as the couple increases the pressure between belt and friction wheels increases. In other words: the pressure with which the belt is clamped between the friction wheels depends on the applied couple. Supporting of the friction wheels close to the outer end has the advantage that the con- verging form of the mutually facing sides of the friction wheels will not change when extremely great forces are exerted on the friction wheels. Finally, the present invention provides a mechanical transmission of the type stated in the preamble wherein the wheel makes external contact with the belt, whereby a radially inward facing surface forms a surface for co- action with the wheel. Using this "mirror-symmetrical" construction a very compact transmission can be realized which can for instance be built into a hub. Particularly envisaged herein are the hubs of cycles, but many other applications are of course also conceivable. The present invention will be further elucidated with reference to the non-limitative embodiments shown in the following figures. Herein: Fig. 1 shows a cross-section of a compactly embodied transmission according to the invention, Fig. 2 shows a cross-section along the line II-II of the transmission shown in fig. 1. Fig. 3 shows three views of an adjusting bush which forms part of the adjusting means for adjusting the eccentricity of the second shaft, Fig. 4 shows three views of an adjusting pin for receiving in the adjusting bush of fig. 3, Fig. 5 shows two views of a bearing bush which forms part of the transmission shown in fig. 1, Fig. 6 shows three views of a friction wheel according to the invention, and Fig. 7 shows two views of a nut for co-action with the friction wheel shown in fig. 6. Fig. 1 shows a mechanical transmission 1 in which a rotatable shaft 2 is coupled to a pair of friction wheels 3,4. The output shaft 7 of mechanical transmission 1 is formed by the drum or hub 7. Mechanical transmission 1 thus takes a very compact form. Placed between friction wheels 3,4 is a fixed friction wheel 8 which on the inside engages on an endless belt 10 built up of separate links 14. These links 14 are only under strain of pres- sure whereby a mutual connection of links 14 is unnecessary. The side surfaces 11 of endless belt 10 co-act with the contact side 5,6 of friction wheels 3,4. A bearing bush 84 is connected to wheel 8. In order to effect a rotational translating movement of wheel 8, the bearing bush 84 is provided with guide elements 73, in this figure cam rollers, which co-act with linear guides 71,72 as shown in fig. 2. In a plate 85 in which are arranged linear guides 71, linear guides 72 are also arranged perpendicularly of the first guides 71. Linear guides 71,72 both also lie perpendicular to the input shaft 2. Plate 85 is linearly displaceable along the stationary cam rollers 74 in that these latter are movable in the linear guide 72. For adjustment of the eccentric position of wheel 8 are provided adjusting means 75 in which is received a rotatable eccentric 76. This rotatable eccentric 76 is also shown in detail in fig. 3. Arranged in eccentric 76 is a groove 86 which co-acts with a protruding cam 87, which cam 87 is mounted on an adjusting pin 88. Through axial displacement of adjusting pin 88 the cam 87 will also displace and the eccentric will thus rotate, whereby the eccentric position of wheel 8 is changed. Adjusting pin 88 is movable in the hollow shaft 2 which is shown in fig. 4. The bearing bush 84 on which wheel 8 is mounted is shown in detail in fig. 5. Fig. 6 shows a friction wheel 3 in three different views, wherein on the axially external side of friction wheel 3 are shown contact surfaces which co-act with contra-contact surfaces 90 forming part of a nut 91 as shown in fig. 7. Nut 91 is placed on the side of friction wheel 3 remote from the other friction wheel 4 in order to support this friction wheel 3. The contra-contact surfaces 90 herein lie against the contact surfaces 89 of friction wheel 3. *****

Claims: CLAIMS 1. Mechanical transmission comprising a frame, a first shaft which is rotatably connected to the frame and to which is fixed a pair of friction wheels placed at a mutual distance, a second shaft which is connected to the frame for rotation eccentrically parallel to the first shaft and which carries a wheel which co-acts with a belt comprising a circular belt contact surface located axially between the friction wheels of the first shaft, and an endless belt of mutually abutting push links, which belt forms mutually opposite side surfaces which co-act with the pair of friction wheels and of which belt a surface facing radially furthest to the outside forms a surface for co-action with the single wheel co-acting with the belt, wherein the friction wheels comprise mutually facing friction surfaces which converge to the outside, characterized in that the transmission (1) comprises guide means for realizing a rotational translating movement of the wheel (8) which is connected to the output shaft (7) and which makes contact with the belt (9) , which guide means are assembled from at least two linear guide tracks (71,72) received mutually perpendicularly in the same plate (85) and guide elements (73,74) co-acting with the linear guide tracks (71,72), wherein guide elements (73) are connected to the wheel (8) for rota- tional translation and guide elements (74) are rigidly connected to the frame whereby the plate (85) is movable in linear manner relative to the frame and the wheel (8) is displaceable in linear manner relative to the plate (85) . 2. Mechanical transmission comprising a frame, a first shaft which is rotatably connected to the frame and to which is fixed a pair of friction wheels placed at a mutual distance, a second shaft which is connected to the frame for rotation eccentrically parallel to the first shaft and which carries a wheel which co-acts with a belt comprising a circular belt contact surface located axially between the friction wheels of the first shaft, and an endless belt of mutually abutting push links, which belt forms mutually opposite side surfaces which co-act with the pair of friction wheels and of which belt a surface facing radially furthest to the outside forms a surface for co-action with the single wheel co-acting with the belt, wherein the friction wheels comprise mutually facing friction surfaces which converge to the outside, characterized in that the transmission (1) comprises adjusting means (75) for adjusting the eccentricity of the wheel (8) connected to the second shaft (7) relative to the first shaft (2), which adjusting means (75) are formed by a rotatable and fixable eccentric (76) . 3. Mechanical transmission comprising a frame, a first shaft which is rotatably connected to the frame and to which is fixed a pair of friction wheels placed at a mutual distance, a second shaft which is connected to the frame for rotation eccentrically parallel to the first shaft and which carries a wheel which co-acts with a belt comprising a circular belt contact surface located axially between the friction wheels of the first shaft, and an endless belt of mutually abutting push links, which belt forms mutually opposite side surfaces which co-act with the pair of friction wheels and of which belt a surface facing radially furthest to the outside forms a surface for co-action with the single wheel co-acting with the belt, wherein the friction wheels comprise mutually facing friction surfaces which converge to the outside, characterized in that the friction wheels (3,4) are supported externally by axially displaceable nuts (77, 78), which nuts (77,78) are provided with contact surfaces (79,80) which co-act with contra-contact surfaces (81,82) arranged close to the external edge of the friction wheels (3,4). 4. Mechanical transmission as claimed in claim 3, characterized in that the contact surfaces (79,80) and the contra-contact surfaces (81,82) form parts of a helix. 5. Mechanical transmission comprising a frame, a first shaft which is rotatably connected to the frame and to which is fixed a pair of friction wheels placed at a mutual distance, a second shaft which is connected to the frame for rotation eccentrically parallel to the first shaft and which carries a wheel which co-acts with a belt comprising a circular belt contact surface located axial- ly between the friction wheels of the first shaft, and an endless belt of mutually abutting push links, which belt forms mutually opposite side surfaces which co-act with the pair of friction wheels and of which belt a surface facing radially furthest to the outside forms a surface for co-action with the single wheel co-acting with the belt, wherein the friction wheels comprise mutually facing friction surfaces which converge to the outside, characterized in that the wheel (8) makes internal contact with the belt (9) , whereby a radially inward facing surface forms a surface (83) for co-action with the wheel (8) . *****

Inventors: HOOGENBERG HEERKE, HOOGENBERG, HEERKE
Applicants: HOOGENBERG HEERKE, HOOGENBERG, HEERKE
Application year: 1997
Main classification: F16H15
IPC codes: F16H15