FR2498715A2 - Variable length pedal crank for bicycle - has crank arm fixed to roller bearing travelling in oval channel cut into crank shaft casing - Google Patents

Abstract

The left and right pedal cranks are symmetrically mounted on the pedal shaft of a bicycle. This shaft turns in the pedal shaft case about a rotational axis. The cranks comprise a slide shaft with a claw which moves along a slide. In the pedal shaft case a bearing surface is formed by a channel whose interior and exterior edges form oval rings. In this channel the claw is fixed to a ball bearing assembly which travels around the channel. The claw is fixed to the inner ring of the bearing which is mobile to allow the claw to drive the slide in a forward and reverse direction as the pedal shaft is rotated.

Description

 The present application for a certificate of addition to the basic patent application No. 80.22758, filed on October 24, 1980, relates to improvements to the cranks, in particular for machines driven by pedals.

 In the main patent application, a crank of variable length has been described. easy to realize, which consists of a slide in which a slide performs a rectilinear reciprocating movement. A ball bearing, in the form of an inner ring and an outer ring. between which circulate balls, is subject to the bottom bracket and has a lug secured to the slide. The bottom bracket is fixed eccentrically to the inner ring and the lug is fixed to the outer ring of the bearing.

 According to this embodiment. it is necessary to fix the ball bearing to the housing by welding, screwing or any other means. This leads to an additional manufacturing step. In addition, the attachment can be fragile.

 Therefore, an object of the present invention is to provide a bottom bracket device according to the main patent which is even easier and more economical to make.

 To achieve this object, the present invention provides a crank of the aforementioned kind, with slide and slide with reciprocating rectilinear movement, but in which a lug, integral with the crank, is rotated according to a raceway subject to the bottom bracket of the crankset , this raceway being constituted by a groove made directly in the housing. The throat is rounded or oval in shape.

 Furthermore, it is expected that the lug is integral with the slide and is fixed on a ball bearing which is movable in the groove.

 Another embodiment consists in fixing the lug on the inner ring of the raceway when the latter is formed of an inner ring and an outer ring movable relative to each other.

 The following description, with reference to the accompanying drawings by way of nonlimiting examples, will enable many to understand how the invention can be put into practice.

 Figure 1 is a sectional front view of the bottom bracket according to the invention.

 FIG. 2 is a schematic view of a groove in which the lug of the bottom bracket device of FIG. 1 circulates.

 Figure 3 is a front sectional view of another embodiment of the bottom bracket device according to the invention.

 In Figure 1, we can see a left crank 6 and a right crank 6 'mounted on a shaft 7 of a crankset, for example a bicycle. The shaft 7 rotates in the bottom bracket 14, around the axis of rotation 15.

 The crank 6, symmetrical to the crank 6 ', consists of a slide 8 provided with a lug 9. This slide can have a back and forth movement in the slide 10. In the bottom bracket, we have made directly a groove 21 forming a raceway. The lug 9 is integral with the slide 8.

 As can be seen, in FIG. 2, the raceway is formed by a groove 21, the outer 23 and inner 22 edges of which form oval rings. In the groove moves the lug 9 which is fixed to a ball bearing 24.

 In Figure 3, the raceway is formed by two inner circular rings 22a and outer 23a. In the groove 21a circulate balls 24. The lug 9 is fixed on the inner ring 22a which is movable; the lug drives the slide 10 in a back and forth movement.

Claims (7)

 1. Crankset device, in particular for cycles, the crank of which consists of a slide in which a slide performs an alternating rectilinear movement, according to claim 1 of the main patent, characterized in that a lug (9), integral with the crank (8, 10) is rotated along a raceway (21) eccentrically secured to the housing (14) of the crankset.  2. Device according to claim 1, characterized in that the raceway (21) consists of a groove made directly in the bottom bracket  3. Device according to claim 1, characterized in that the lug (9) is integral with the slide (10).  4. Device according to claim 2, characterized in that the lug (9) is fixed on a ball bearing (24) which is movable in the groove (21).  5. Device according to claim 1 characterized in that the lug (9) is fixed to the inner ring (22a) of the raceway (21a)  6. Device according to any one of claims 1 to 5, characterized in that the groove (21) is of oval shape.  7. Device according to any one of claims 1 to 5, characterized in that the groove (21) is of rounded shape.