FR2777856A1 - Bicycle pedal with hydrostatic bearing - Google Patents

Abstract

The pedal comprises a body inside which is a bearing (7) housing the pedal spindle (6). The bearing is located in a long bearing block (8) having a cavity (9). The cavity walls define a bearing between the walls and the spindle into which hydraulic liquid is injected through inlet orifices (13,14). The liquid is evacuated through outlet orifices (16-18). The hydraulic circuit includes an actuator forming a pump located on the pedal which supplies hydraulic liquid to the bearing during pedaling.

Description

The invention relates to the bicycle pedals with hydrostatic bearings.

  bicycle pedals. In the state of the art, these pedals are provided with bearings in the form of ball bearings which carry the pedal axis connected to the crankset. These ball bearings are generally satisfactory since they give a relatively low coefficient of friction, but they are expensive to manufacture and are nevertheless exposed to wear and tear caused by variable stresses.

during each turn of the pedal.

  The object of the invention is to propose a bicycle pedal comprising a bearing which makes it possible to remedy the drawbacks of pedals provided with conventional bearings and which offers the following advantages: - absence of wear; - extremely low coefficient of friction; - absence of jerky friction; - very high stiffness, making it possible to maintain precise positioning of the pedal axis despite significant load variations (downwards and then upwards);

  - inexistence of stress concentrations.

  The invention relates to a bicycle pedal comprising a pedal body inside which are provided bearing means for accommodating the pedal axle connected to the pedal of the bicycle, characterized in that the bearing means comprise a hydraulic circuit comprising hydraulic means

  constituting a hydrostatic bearing.

  According to other features of the invention: - the hydraulic circuit comprises hydraulic control members arranged on the pedal body to supply hydraulic fluid to the bearing when the pedal is actuated; the hydraulic control members comprise a jack constituting a hydraulic pump capable of being actuated by the toe of the cyclist, this jack being connected to a reservoir of hydraulic liquid by a suction pipe on the one hand and by a pipe supply and return on the other hand in which the hydrostatic bearing is inserted; - a pressure accumulator is inserted in the supply and return duct, upstream of the hydrostatic bearing; - Each conduit connected to the cylinder respectively comprises a non-return valve; - The bearing means are arranged in an elongated bearing block embedded in the pedal body and comprising a cavity, the walls of which define a pad with a determined clearance between said walls and the pedal axis in order to delimit a gap between said walls and the surface of the pedal shaft for injecting hydraulic fluid therein through at least one inlet port, the liquid then being able to be evacuated therefrom through at least one outlet port; - The cavity is on one side delimited by an O-ring seal through which the pedal axis passes; - The inlet opens into a recess in the middle area of the cavity; - The outlet orifice is arranged in an end zone of the cavity; - at least one outlet orifice is arranged in each end zone of the cavity;

  - the bearing block is made up of two half

shells attached to each other;

  - the cylinder is constituted by an elastic dome.

  The invention will now be described with reference to the accompanying drawings which show, by way of example, an embodiment of the pedal according to the invention. In the drawings: - Figure 1 shows a quick-fixing pedal, provided with a hydrostatic bearing according to the invention, - Figure 2 is a cross-sectional view of a hydrostatic bearing block according to the invention; - Figure 3 is a longitudinal sectional view of the bearing block of Figure 2; - Figure 4 is a diagram showing the circuit

  the hydrostatic bearing according to the invention.

  Figure 1 shows a pedal 1 provided with a quick fastening composed of a plate 2 fixed under the sole of a shoe and a front claw 3 and a rear claw 4 between which the plate can be clamped to retain the sole against the pedal body 5. The pedal axis 6, connected to a pedal not shown in the figures, is housed in a hydrostatic bearing 7 illustrated in Figures 2 and 3. This hydrostatic bearing is connected to a hydraulic circuit illustrated in Figure 4 and whose implementation and

  operation will be described in detail later.

  The hydrostatic bearing 7 is formed in a generally parallelepiped elongated bearing block 8 embedded in the pedal body 5. This bearing block comprises an elongated cavity 9 open on one side in order to receive the pedal axis 6 which extends through an O-ring 10 disposed near the opening 11 of the

cavity.

  The bearing block 8 is in the illustrated example composed of two half shells 8a, 8b fixed to one another. The pedal axis 6 has a free bulbous end to cooperate with a shape similar to that of the cavity 9 so that this end remains trapped in the cavity, the rest of the pedal axis being slightly conical by narrowing outwards, which also corresponds to the general shape of

cavity walls.

  The walls of the cavity 9 define a bearing with a determined clearance between these walls and the surface of the pedal axis 6 in order to delimit there a gap 12 intended to receive the hydraulic liquid by inlet orifices 13, 14 made in the wall of the block, in a middle area of the cavity and which are arranged

one opposite the other.

  Preferably, the hydraulic fluid consists of a suitable oil, but a fluid can be used

any lubricant.

  In order to facilitate the penetration and distribution of the hydraulic fluid in the cavity 9, the inlet orifices 13, 14 open into a respective recess 15

formed in this middle zone.

  The hydraulic fluid is evacuated by outlet orifices, two of which, 16 and 17, are arranged in an end zone of the cavity 9, near the seal 10. These two outlet orifices 16, 17 are arranged one opposite the other. A third outlet port 18 is disposed in the opposite end region, in

the alignment of the pedal axis 6.

  FIG. 4 schematically shows an embodiment of the hydraulic circuit according to the invention. This circuit includes a hydraulic fluid reservoir 19 which by a suction pipe "a" is connected to a jack 20, a non-return valve 21 being inserted in the pipe

"a", near the jack 20.

  Each non-return valve 21 can be constituted by

a rubber valve.

  The cylinder piston 22 is constantly biased towards a suction position by elastic means 23 which in the example illustrated are constituted by a spring. The cylinder is actuated, against the action of the spring, by the toe of the cyclist to discharge the hydraulic fluid into a supply conduit "b" opening into the inlet orifices 13, 14 of the cavity 9 of the hydrostatic bearing 7. The jack 20 may advantageously be constituted by an inflating dome made of rubber or of another flexible and elastic material, as illustrated in FIG. 1. The outlet orifices 16 to 18 of the cavity 9 of the bearing communicate with a return pipe "c" connected to the reservoir 19. The pipes "a", "b" and "c" form

thus a closed loop.

  In order to maintain the pressure in the hydrostatic bearing 7 during pedaling, a pressure accumulator 24 is inserted in the supply duct

"b", upstream of the landing.

  When the user places his toe in place on the pedal, he presses against the dome 20 acting as a hydraulic cylinder, the liquid therein will be expelled in the supply duct "b", to be supplied to the pressure accumulator 24 and then towards the hydrostatic bearing 7. When the user begins to pedal and when his foot goes up, the jack 22 will be filled again thanks to the innate elasticity of the dome, creating a depression in the chamber cylinder. The hydraulic fluid will thus be supplied under pressure in the cavity 9 of the bearing 7 and in the meantime, the pressure accumulator 24 makes it possible to constantly maintain the bearing in pressure. At start-up and at idle, the bearing defined by the walls of the cavity 9 alone guides the axis in rotation but

  remains lubricated by hydraulic fluid.

  As already mentioned, the conduit "c" then allows

  the hydraulic fluid to return to the tank 19.

  Thanks to the cavity 9 forming a bearing, lubrication is thus obtained by complete film and the load is transmitted through this lubricating film where the pressure is maintained by means of the jack 20 acting as a pump and the pressure accumulator 24. During the rotational movement of the crankset, an oscillating movement of the jack 20 is obtained as a function of the variable pressure which is exerted on

this one for each round.

  This effect is obtained even if a quick fastening of the type illustrated in FIG. 1 is used with a shim fixed under the sole of the shoe and which cooperates with claws on the pedal body, or if it is

  an even more conventional fixation.

  Thanks to the invention is thus obtained a pedal provided with a bearing having all the advantages

specified above.

Claims (12)

  1. Bicycle pedal comprising a pedal body (5) inside which are provided bearing means (7) for housing the pedal axle (6) connected to the pedal of the bicycle, characterized in that the means forming a bearing (7) comprise a hydraulic circuit comprising hydraulic means <7 to 9)   constituting a hydrostatic bearing.   2. bicycle pedal according to claim 1, characterized in that the hydraulic circuit comprises hydraulic control members (20) arranged on the pedal body (5) for supplying hydraulic fluid   towards the bearing (7) when the crankset is actuated.   3. bicycle pedal according to claim 2, characterized in that the hydraulic control members (20) comprise a jack constituting a hydraulic pump capable of being actuated by the toe of the cyclist, this jack (20) being connected to a hydraulic fluid reservoir (19) by a suction pipe ("a") on the one hand and by a supply and return pipe ("b", "c") on the other hand in   which is inserted the hydrostatic bearing (7).   4. Bicycle pedal according to claim 3, characterized in that a pressure accumulator (24) is inserted in the supply and return pipe   ("b", "c"), upstream of the hydrostatic bearing (7).   5. Bicycle pedal according to claim 3 or 4, characterized in that each conduit ("a", "b") connected to the cylinder respectively comprises a non-return valve (21).   6. Bicycle pedal according to any one of   previous claims, characterized in that the   bearing means (7) are arranged in an elongated bearing block (8) embedded in the pedal body (5) and comprising a cavity (9), the walls of which define a bearing with a determined clearance between said walls and the axis pedal (6) to delimit a gap between said walls and the surface of the pedal axis to inject hydraulic fluid therein through at least one inlet (13, 14), the liquid can then be evacuated therefrom at least one outlet (16 to 18). 7. Bicycle pedal according to claim 6, characterized in that the cavity (9) is on one side delimited by an O-ring seal (10) through   which passes the pedal pin (6).   8. Bicycle pedal according to claim 6 or 7, characterized in that said at least one inlet orifice (13, 14) opens into a recess (15) formed   in the middle area of the cavity (9).   9. Bicycle pedal according to any one of   claims 6 to 8, characterized in that said at   at least one outlet (16 to 18) is disposed in a   end zone of the cavity (9).   10. Bicycle pedal according to claim 9, characterized in that at least one outlet (16, 17; 18) is disposed in each end region of the cavity (9).   11. Bicycle pedal according to any one of   Claims 6 to 10, characterized in that the block of   bearing (8) is composed of two half-shells (8a, 8b) attached to each other.   12. Bicycle pedal according to any one of   Claims 3 to 11, characterized in that the cylinder   (20) is constituted by an elastic dome.