Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62M—RIDER PROPULSION OF WHEELED VEHICLES OR SLEDGES; POWERED PROPULSION OF SLEDGES OR SINGLE-TRACK CYCLES; TRANSMISSIONS SPECIALLY ADAPTED FOR SUCH VEHICLES
  • B62M1/00—Rider propulsion of wheeled vehicles
  • B62M1/36—Rider propulsion of wheeled vehicles with rotary cranks, e.g. with pedal cranks
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62M—RIDER PROPULSION OF WHEELED VEHICLES OR SLEDGES; POWERED PROPULSION OF SLEDGES OR SINGLE-TRACK CYCLES; TRANSMISSIONS SPECIALLY ADAPTED FOR SUCH VEHICLES
  • B62M3/00—Construction of cranks operated by hand or foot
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62M—RIDER PROPULSION OF WHEELED VEHICLES OR SLEDGES; POWERED PROPULSION OF SLEDGES OR SINGLE-TRACK CYCLES; TRANSMISSIONS SPECIALLY ADAPTED FOR SUCH VEHICLES
  • B62M9/00—Transmissions characterised by use of an endless chain, belt, or the like
  • B62M9/04—Transmissions characterised by use of an endless chain, belt, or the like of changeable ratio
  • B62M9/06—Transmissions characterised by use of an endless chain, belt, or the like of changeable ratio using a single chain, belt, or the like
  • B62M9/10—Transmissions characterised by use of an endless chain, belt, or the like of changeable ratio using a single chain, belt, or the like involving different-sized wheels, e.g. rear sprocket chain wheels selectively engaged by the chain, belt, or the like
  • B62M9/105—Transmissions characterised by use of an endless chain, belt, or the like of changeable ratio using a single chain, belt, or the like involving different-sized wheels, e.g. rear sprocket chain wheels selectively engaged by the chain, belt, or the like involving front sprocket chain-wheels engaged by the chain, belt or the like

Definitions

• the present invention relates to a device for transmitting power from two maneuvering arms to a chain or the like, in particular a bicycle crankset, in which the two maneuvering arms in reverse arrangement rotate a toothed wheel or the like.
• cranks In a conventional bicycle crankset, the two operating arms, called cranks, are rigidly fixed on the rotation shaft, mounted to rotate freely relative to the frame of the bicycle by means of a rolling bearing.
• the length of the cranks, the number of teeth of the toothed wheel and the radius of said wheel are fixed parameters which determine, for a given force applied to the pedal by the user, the amount of work affecting the chain for the rotation of the rear wheel drive pinion, that is to say for a determined time to transmit the power deployed by the user.
• the aim set by the applicant is to improve the efficiency of such a power transmission device, for an instantaneous force communicated by the user, without modifying the above fixed parameters, namely the length of the arms of operation, the number of teeth of the toothed wheel and the radius of the latter relative to the axis of rotation.
• such a device comprises: a) a first power transmitter assembly, comprising a rotation shaft, the two operating arms rigidly mounted on the rotation shaft, and near said shaft n bearing faces, preferably radial, facing in the direction of rotation, b) and a second power receiver assembly which comprises:
• central part mounted free to rotate around said rotation shaft, said central part being constituted by a first substantially flat part in the extension of the toothed wheel and by n second external parts delimiting n counter-bearing faces, capable of being in engagement with the n bearing faces of the first emitting element when the operating arms are actuated; moreover each face of the abutment is towards the free end of the second external part, arranged in overhang and along the first part of the second receiver assembly, being connected to the latter by a transverse connection.
• the part carrying on its periphery the toothed wheel is not rigidly fixed on the rotation shaft.
• the first transmitting element and the second power receiving element are two independent elements, the second being driven by the action of the first thanks to the bearing faces which engage against the counter-bearing faces of the second element.
• the application of this transmission owing to the fact that the bearing faces are on cantilevered parts and offset relative to the first part of the central part of the receiver assembly is in fact carried out at the level of the cross links.
• a rolling bearing is disposed between the rotation shaft of the transmitter assembly and the first part of the receiver assembly, thus allowing the free rotation of said receiver assembly relative to this rotation shaft.
• the transverse connections are close to the toothed wheel. The applicant has in fact found that the longer the cantilever length of the second external parts is greater and therefore approaches the length available between the rotation shaft and the toothed wheel and the more the improvement is significant.
• the number n is equal to 4 or 5.
• the four bearing faces and the four abutment faces are on two perpendicular planes passing through the axis of rotation.
• the ratio between on the one hand the height of the bearing face and on the other hand the cantilever length of each second external part is included in a range between 0.1 and 0 , 4.
• each of these second parts is an annular portion making an angle of about 30 °.
• each second external part of the receiving assembly has the form of an annular portion
• the emitting element has, between two successive bearing faces and in its direction of rotation, a convex external shape, first circular , centered on the axis of rotation, in the zone adjoining the lower edge of this second external part of the receiving element, then an external shape curved up to the top of the next bearing face.
• said receiver assembly comprises n spacers, each extending between two second successive external parts.
• each spacer is shaped to allow a slight clearance between the bearing faces and the counter-bearing faces vis-à-vis.
• FIG. 1 is a partial perspective view of the crankset according to the invention
• FIG. 2 is a partial schematic representation in plan of the first power transmitter assembly
• FIG. 3 is a schematic representation in section along the axis III-III of FIG. 2
• FIG. 4 is a partial schematic representation in plan of the second power receiving element
• FIG. 5 is a schematic representation in partial section along the axis V-V of FIG. 4.
• the crankset 1 of the invention is conventionally made up of two cranks 2 (only one of which is shown partially in FIG. 1), a shaft 3 of rotation and a toothed wheel 4, on which a chain stretched between the pedals and the free wheel of the rear wheel of the bicycle.
• the two cranks 2 are fixed radially and in an opposite arrangement to the ends of the rotation shaft 3.
• This rotation shaft 3 is mounted to rotate freely relative to the frame of the bicycle by means of a rolling bearing.
• the toothed wheel 4 is located at the periphery of a one-piece circular element or in two parts which is rigidly fixed on the rotation shaft in the immediate vicinity of the pedal. of right.
• the toothed wheel 4 is independent of the rotation shaft 3, the power transmission between the cranks 2 and said toothed wheel 4 not being a direct transmission by a fixed intermediate element but being an indirect transmission as will be explained below.
• the crankset 1 comprises a first power transmitter assembly 5, which comprises the two cranks 2 and the rotation shaft 3 at the ends of which the two cranks are rigidly mounted, in an opposite arrangement;
• the rotation shaft 3 has the distinction of having a plurality n of planar faces, regularly arranged on its outer periphery. These planar faces, called bearing faces, are turned forward in the usual direction of rotation of the crankset. They are preferably radial; in other words their general direction passes through the axis of rotation of the shaft 3.
• the rotation shaft 3 has on its outer periphery four bearing faces 6.
• the crankset 1 of the invention also comprises a second assembly 7, power receiver, which is independent of the first assembly 5 power transmitter but intended to cooperate with the latter to ensure the transmission of power from the cranks 2 to the toothed wheel 4.
• This second assembly 7 comprises the toothed wheel 4 and a central part 8 which is mounted to rotate freely around the rotation shaft 3.
• This central part 8 is in the form of a part 9 mounted to the interior of the toothed wheel 4 and fixed to the latter by fixing points 10, having a substantially planar face from which projects outwardly a plurality n of counter-support elements 11.
• a counter-supporting element 1 1 appears, in the example illustrated, as a block having a height h. given and, seen in plan, the shape of an annular portion of an angular sector of angle a making approximately 30 ° .
• This block is largely cantilevered relative to the flat face of the part 9 being integral with the latter by a zone 13, forming a transverse connection, which is the zone of the element 1 1 most close to the toothed wheel 4.
• the counter-supporting face 1 2 is located on one of the lateral uprights 19, perpendicular to the flat face of the part 9, more precisely in the zone of this lateral upright 19 which is opposite the transverse link 13, that is to say in the most cantilevered zone of the counter-support element 11.
• the part 9 has a central recess which makes it possible to place, during the mounting of the crankset 1, the n bearing faces 6, of the rotation shaft 3, opposite the ⁇ counter-bearing faces 1 2 of the second set 7, power receiver.
• a toothed wheel can be placed on the circular periphery of the central part 8. As this is a double chainwheel, this second toothed wheel may have a number of teeth less than that 4 fixed by the fixing points 10.
• the second element 7, power receiver is mounted to rotate freely relative to the rotation shaft 3 in particular by a rolling bearing 14. This arrangement allows relative movement between the two sets 5,7 respectively transmitter and power receiver when the pedal is actuated.
• Figure 2 is partially shown in plan, the first power assembly 5. More specifically are shown in this Figure 2 the part 1 5 carrying the bearing faces 6 and an arm 2a of a crank 2. Are therefore not shown in this figure 2 the rotation shaft 3, the pedal fitted to this arm 2a as well as the part carrying the other crank.
• the four bearing faces 6, in the example illustrated, are in two perpendicular planes passing through the axis 1 6 of rotation of the shaft 3. Each bearing face 6 has a determined height e, for example l 'order of 5mm. Said bearing faces 6 are carried by the middle portion 1 5a of the part 1 5 ( Figure 3).
• This middle portion 15a from the lower end 6a of a bearing face given to the upper end 6b_ of the adjacent bearing face, in the normal direction of rotation of the crankset 1, according to arrow F, a profile which is, in cross section, first of all circular with respect to the axis of rotation 1 6, according to a first zone 1 7, then of curved and ascending form according to a second zone 1 8.
• the part 1 5 has, on either side of the middle portion 1 5a, a first right side portion 1 5b on which is fixed radially the arm 2a of a crank 2 and a second left side portion 1 5c serving externally support for a rolling bearing allowing the free rotation of the second power receiver assembly 7 relative to the first power transmitter assembly 5.
• the rotation shaft 3, not shown in the figures, has an external profile which is adapted to match the internal profile, in particular the square of the middle portion 1 5a of the part 1 5.
• FIGS. 4 and 5 is partially illustrated, in plan, the second power receiver element 7. More specifically, these figures illustrate the central part 8, which comes in the interior extension of the toothed wheel 4 not shown.
• This central part 8 consists of a circular plate 9 which supports on its flat face 9a located on the right of the crankset the four blocks 1 1 in overhang connected to said face 9a by transverse links 1 3.
• Each block 1 1 has a height D above the transverse connection 13 and in plan an annular shape delimiting an angular portion of about 30 ° .
• Each block 1 1 comprises four lateral uprights, perpendicular to the face 9a of the part 9, namely two rectilinear uprights 19,20, successively in the direction of the arrow F and two curved uprights respectively 21, 22 from the axis of rotation 1 6.
• the transverse connections 13 are located at the curved upright 22 furthest from the axis of rotation 1 6 and therefore closest to the toothed wheel 4; the four blocks 1 1 are distributed symmetrically with respect to the axis of rotation 1 6.
• FIG. 4 are illustrated under the reference 23 five circular fixing zones at the level of which the toothed wheel 4 is fixed on the part 9.
• it may be a first toothed wheel of a given diameter and having a number of given teeth, fixed on the right face 9a of the part 9 and of a second toothed wheel of a diameter and of a lower number of teeth fixed on the left face of the part 9 at the level of said fixing zones 23.
• spacers 24 intended on the one hand to form a rigid connection between said blocks 1 1 and on the other hand to serve as a stop avoiding excessive movement of the part 1 5 of the first set 5 power transmitter when the cranks are actuated 2.
• Each spacer 24, as illustrated in Figure 3, extends between two successive rectilinear lateral uprights 20, 1 9 of two adjacent blocks 1 1.
• This spacer 24 is not fixed directly to the part 9 so that all the spacers 24 are also cantilevered with respect to the face 9a of said part 9.
• each spacer 24 forms an angular portion of approximately 60 ° , comprising four lateral uprights perpendicular to the face 9a of the part 9, namely two straight uprights 25,26 in the direction of the arrow F and two curved uprights 27,27 'from the axis of rotation 1 6.
• the two rectilinear uprights 25, 26 are applied to the two rectilinear uprights 20, 1 9 of two successive cantilever blocks 1 1.
• the curved upright 27, closest to the axis of rotation 1 6, has from the rectilinear upright 25 a first circular zone 28, which is in the exact extension of the curved upright 21 of the cantilever block false 1 1 on which the rectilinear upright 25 rests and a second curved and ascending zone 29 so that the rectilinear upright 26 of the spacer 24 does not rest on the rectilinear upright 19 of the cantilever block 1 1 next on a height H.
• the outer profile of the middle portion 15a of the part 15 and the inner profile of the aforementioned curved uprights 21, 27 are provided so that the first assembly 5, power transmitter, can have a certain play inside this housing during actuation of the cranks 2.
• a counter-bearing face 12 consists in the most cantilevered part of a rectilinear upright 19 of a block 1 1, at the height zone H not covered by the adjacent spacer 24.
• the clearance existing between the first element 5, power transmitter and the second element 7, power receiver, is a function of the profiles respectively of the ascending zone 18 of the part 15 with regard to the assembly 5 and the zone 29 of the curved upright 27 of the spacer 24 with regard to the second set 7.
• the height e of the bearing faces 6 was about 5mm, while the length L overhanging each block 1 1 was 32mm. The ratio between these two lengths was therefore 0.15.
• the user When the pedal is actuated, the user causes the rotation shaft 3 to enter into rotation by pressing on the pedals fitted to the end of the arms 2a of the cranks 2. This rotation correlatively causes the rotation of the part 15 controlled by the tree 3.
• the faces bearing 6 carried by the middle portion 15a of the part 15 are applied on the counter-bearing faces 12 of the cantilevered blocks 1 1.
• the power applied to the abutment faces 12 by the first assembly 5, a power transmitter is transmitted to the toothed wheel 4 via the transverse connections 13.
• the efficiency of this transmission is d 'all the more important that the ratio between the height e of the bearing face 6 and the length L overhanging of the block 1 1 is low.
• this ratio is between 0.1 and 0.4.
• the present invention is not limited to the precise embodiment which has just been described by way of non-exhaustive example.
• the number and the geometry of the cantilevered blocks 1 1 are not limited to the example described and illustrated.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Transmission Devices (AREA)

Applications Claiming Priority (3)

Publications (1)

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ID=9514498

Family Applications (1)

Country Status (3)

Cited By (1)

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Family Cites Families (3)

• 1997
  • 1997-12-08 FR FR9715728A patent/FR2772092B1/fr not_active Expired - Fee Related
• 1998
  • 1998-12-07 EP EP98958969A patent/EP0958167A1/de not_active Withdrawn
  • 1998-12-07 WO PCT/FR1998/002646 patent/WO1999029565A1/fr not_active Application Discontinuation

Non-Patent Citations (1)

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