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
  • B62M3/00—Construction of cranks operated by hand or foot
  • B62M3/02—Construction of cranks operated by hand or foot of adjustable length
  • B62M3/04—Construction of cranks operated by hand or foot of adjustable length automatically adjusting

Definitions

• the invention relates to a pedal crank drive for bicycles or the like with pedal cranks, the effective length of which is increased by an adjustment mechanism during operation when moving downwards and reduced when moving upwards.
• the object of the present invention is to improve this known pedal crank drive in such a way that a harmonious drive curve results with optimum power development.
• this object is achieved in that the maximum effective length of the pedal cranks is in the angular range of 135 ° ⁇ 30 °, measured in the drive direction from the top dead center of the pedal position.
• the maximum is preferably in the angular range of 135 ° ⁇ 15 °.
• the maximum effective length of the pedal cranks is within a limited adjustment range adjustable.
• the adjustment range is preferably such that it is 135 ° ⁇ 45 °, measured from the top dead center of the pedal position; in this case it is also possible to set the theoretical maximum point of 90 °, e.g. for experimental purposes.
• the adjustment can be carried out in such a way that the set position is infinitely adjustable, for example when the adjustment mechanism is set up. However, it is also It is possible to carry out the adjustment in a stepless manner in the operation of the bicycle, or else in latching steps, via an actuating lever, for example in order to adapt the drive behavior to the respective requirements during a longer journey.
• the present invention can be used particularly advantageously in a pedal crank drive according to EP-B1-215,938, in which each of the pedal cranks consists of two parts which can be displaced relative to one another (crank arm and pedal bracket arm), the pedal bracket arm being opposite by means of a control pin arranged thereon the crank arm is displaced, in which a bearing arrangement is provided eccentrically to the pedal crank axis for each pedal crank, the fixed bearing part of which is held on the frame and the control pin is rotatably mounted on the rotatable bearing part and one in rotation with respect to the pedal crank axis describes an eccentric circular path.
• the fixed bearing part is held on the frame in such a relative position that the maximum of the eccentric circular path is in the range of 135 ° ⁇ 30 °, in particular 135 ° ⁇ 15 °, with respect to the top dead center the pedal position is.
• the fixed bearing parts of each of the movement mechanisms are preferably held in the region of the bottom bracket by means of a carrier disk on both sides of the frame.
• the carrier disks preferably have elongated holes and are adjustably fastened to the frame by corresponding fastening means.
• FIG. 1 shows a perspective view of the assignment of the individual parts of the pedal crank drive according to the invention in an exploded view
• FIG. 2 shows a schematic movement diagram of the pedal crank drive according to the invention in four different positions A, B, C and D;
• FIG. 3 shows a modified carrier disk for the adjustable holder
• FIG. 5 shows a section through the arrangement according to FIG. 4.
• FIG. 1 shows a detail from a bicycle frame in the area of the bottom bracket and is given the reference number 61.
• a bearing arrangement 54 is fastened to this frame 61 by means of a carrier disk 39, which is designed as an annular ball bearing in FIG. 1. Details of the attachment will be explained in detail later.
• the bearing arrangement 54 has a fixed bearing part 57 and a rotatable bearing part 56, and on the latter a bearing bush 55 for receiving a control pin 25 of a pedal crank 51 is fastened.
• the pedal crank 51 consists of a crank arm and a pedal support arm 2, which is provided at its end with a threaded bore into which a pedal (not shown) can be screwed.
• the reference numeral 53 denotes the pedal axis here.
• On the crank arm 52 is a pedal crank 8 is arranged, which has an inner square, which can be plugged onto a corresponding outer square of a pedal crank shaft 22 and fastened by screwing.
• This pedal crank drive described so far is arranged (in the drawing in FIG. 1) on the left side of the pedal bracket.
• This pedal crank drive is shown in the drawing Not shown for the sake of simplicity; however, it works in the same way.
• reference numeral 75 represents the center of the bearing arrangement 54, which is shifted forward and downward (in FIG. 2 to the right below) with respect to the pedal crank axis 22 in the bicycle.
• the bearing bush 55 with the control pin 25 mounted therein describes a circular path when the rotatable bearing part 56 rotates, which is indicated in FIG. 2 by a dash-dotted line 76.
• the pedal support arm 2 is thus displaced with respect to the crank arm 52 and thus the pedal crank axis 22 over the course of a crank stroke via the control pin 25 arranged on it, and different lever arms result between the pedal axis and the pedal crank axis in the course of a pedal crank revolution.
• the pedal axis 53 describes an essentially eccentric circular path with respect to the pedal crank axis 22, which means that a larger lever arm is available when the bicycle is moving or the like when the pedals are descending, while a smaller path is taken when the pedals are being returned must become.
• the position D with the maximum lever arm 1 D lies on a dash-dotted line 48 which forms an angle 50 of 135 ° with respect to the top dead center T 0 .
• FIG. 3 shows a special embodiment of the carrier disk 39 which is only roughly shown in FIG. 1 and which serves to hold the bearing arrangement 54 on the frame 61.
• the carrier disk 39b shown in FIG. 3 has two elongated holes 49 which are arc-shaped around the pedal crank axis 22 in order to make the fastening of the carrier disk 39b to the frame 61 adjustable by a limited angular range.
• the fasteners are not shown in detail here.
• the bearing arrangement of the adjusting mechanism is indicated by dash-dotted lines, and the dash-dotted line 48 indicates the maximum of the effective length 1 of the pedal crank 51 (FIGS. 1 and 2).
• the bearing arrangement 54 can, according to the dash-dotted line 48, by the average angle of 135 ° on both sides by 30 ° each, that is, by an entire angle 47 pivoted from ⁇ 30 ° and fastened to the frame 61 in any position within this area 47 by means of the elongated holes 49.
• This adjustability of the bearing arrangement 54 that is to say the adjustment mechanism for the crank arm length of the pedal crank, can take place in such a way that this adjustment takes place for the purpose of a one-time adjustment.
• a mechanism (not shown) with which the actuation lever is used for adjustment during the operation of the bicycle or the like, and this can be done either continuously or in latching steps.
• the initially specified angle of 135 ° relative to the top dead center T 0 can of course fluctuate within a certain range.
• This angle is preferably 135 ° ⁇ 30 °, but a range of 135 ° ⁇ 15 ° is preferred.
• this angle 50 is adjustable, it is advisable to provide an adjustment possibility by the mean angle of 135 ° by ⁇ 45 ° in order to place the maximum crank arm length at 90 ° at one end of the range, for example in order to do so To be able to carry out experiments, even if the pedaling movement is not as smooth at this angle as at an angle of 135 °.
• the performance of the pedal crank drive according to the invention can be further easily adapted to the needs of the operator if the control pin 25 can be arranged in different positions relative to the pedal support arm 2, which is facilitated by several bores 58 (FIG. 2) becomes. If the control pin 25 is in the bore 58 indicated in FIG. 3 screwed in, the lever arm of the pedal crank is extended by a small amount; however, this amount must also be applied during the return movement.
• FIGS. 4 and 5 show a preferred bearing arrangement 83, the details of which are described below and which can be used instead of the bearing arrangement 54 of FIG. 1.
• the bearing arrangement 83 consists of a fixed, inner bearing part 29 which is pushed with an opening 84 over the pedal crank axis 22 and is fastened to the bicycle frame 61.
• the center of the bearing arrangement 83 is offset from the pedal crank axis 22 or the opening 84 as in FIG. 2.
• a rotatable bearing part 30 carries on bearing journals 32 bearing rollers 33 which roll on an annular bearing track 31 of the fixed bearing part 29.
• four or more bearing rollers can also be provided; However, at least three rollers are required, which are evenly distributed around the circumference, in order to ensure that the rotatable bearing part 30 is properly fixed relative to the fixed bearing part 29.
• the bearing rollers 33 are preferably designed as roller bearings attached to the bearing journal 32.
• the attachment of the pedal crank drive, ie in particular the bearing arrangements 54 (or the bearing arrangements 83 according to FIGS. 4 and 5) on both sides of the frame 61 can be seen in FIGS. 1 and 3.
• a carrier disk 39, 39a and 39b with a recess 60 and 62 therein are pushed onto the two ends of a bottom bracket tube 40.
• the recesses 60 and 62 are flanged and adapted for a firm fit on the ends of the bottom bracket tube 40.
• the carrier disk 39a provided for the right side (seen in FIG. 1) simultaneously represents an inner part of a chain protection box.
• a clamp arrangement (not shown) is provided for axially fixing the bearing arrangements to the frame 61, but this is not the case here must be described further.

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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 (2)

Publications (1)

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ID=6877906

Family Applications (1)

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Cited By (8)

Families Citing this family (3)

Citations (5)

• 1992
  • 1992-03-31 DE DE9204330U patent/DE9204330U1/de not_active Expired - Lifetime
• 1993
  • 1993-03-26 WO PCT/EP1993/000742 patent/WO1993019976A1/de active Application Filing

Patent Citations (5)

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