FR2807713A1 - Energy wheel, for transmitting engine torque, has compressible chamber filled with incompressible liquid to form liquid piston which generates additional torque when engaged with ground support surface - Google Patents

Abstract

The wheel (1), which has a tire (2), is provided near its circumference with a compressible chamber (3) filled with an incompressible liquid so as to define a liquid piston. The chamber generates an additional torque in the same direction as the engine torque when it engages with the ground support surface which brings about the compression of the chamber.

Description

 The invention relates to an improved wheel, designed to optimize transmission of a motor torque.

In the field of transport, as elsewhere in the industry, it is regularly used, for the transmission of couples, to wheels cooperating with a surface with other intermediate members, gears type, Gold, well known only because mechanical and dynamic stresses, the entirety of a driving torque can not be transmitted effectively to these wheels, that these constitute an intermediate or the final transmission member of said pair.

The object of the invention is to provide the wheels of the type in question with appropriate elements, suitable for optimizing the transmission of this pair.

According to the invention this wheel is provided in the vicinity of its circumference with at least one compressible chamber, filled with an incompressible liquid, thereby defining a liquid piston, said chamber being intended to generate an additional torque, oriented in the same direction the driving torque, and cooperating directly or indirectly with a fixed or movable bearing surface, resulting in the compression of the compressible chamber and corollary by the displacement of said liquid piston in a single degree of freedom.

In other words, the invention consists in conferring a portion of the potential energy inherent in a mass determined in kinetic energy using the complementary elements with which said wheel is capable of cooperating.

According to a first embodiment of the invention, the wheel in question is a rim provided at its periphery with a tire, whose inner face of the tread receives two flexible tubes, positioned in the extension of one of the another so as to extend over the entire inner circumference of said tire, and extending substantially in two half-circles, thus constituting said compressible chamber, each of these tubes being closed at its two ends, respectively an upstream end and a downstream end, the downstream end of said tubes further receiving an elastic cushion secured to the tube at this level. The wheel is further provided, vertically above the upstream end of each of said tubes, with a fixed and rigid radial pad, capable of also defining a bearing and counter-reaction face for each of said tubes when the latter co-operates. with the first bearing surface, in this case constituted by the surface on which the wheel rests and in particular the road or the ground, so as to cause at this level the effective compression of the tube, and therefore the displacement of the piston liquid within the tube, this displacement being able to take place, given the relative rigidity of the tube, that according to its main dimension, thus conferring a single degree of freedom to said piston.

According to one characteristic of the invention, the incompressible liquid is constituted by water and elastic cushion is made of rubber or elastomer.

According to a second embodiment of the invention, the wheel is provided with a groove or peripheral ring comprising two collinear sections and extending substantially in two half-circles, each of said sections being closed at its two ends, respectively an upstream end. and a downstream end, and being defined by a rigid cylindrical wall over its entire circumference with the exception of a window facing outwards, positioned facing the upstream end. This window constitutes the zone of cooperation with the first bearing surface, at which level it is closed by a flexible membrane, said windows being positioned diametrically with respect to one another. The downstream end of each of the sections comprises a rigid incompressible extension, within which secured elastic cushion, similar to that previously described.

These two throat sections are filled with an incompressible liquid, including water.

In this embodiment, the bearing surface is constituted by a idler roller or a belt mounted between two idle rollers, or any other equivalent system.

 This embodiment is clearly adapted for the constitution of an intermediate transfer wheel of a motor torque, and may be associated with a pulley, relaying the transmission of energy. another embodiment, the wheel is intended to rest on rails, and the compressible chamber consists of two collinear peripheral annular rings, independent of one another, filled with an incompressible liquid. These rings each have an upstream end and a downstream end, the latter receiving an elastic cushion. The upstream end of the rings is provided with an outwardly directed window, and closed by means of a piston, said piston integrating at its head a ball, intended to cooperate with the upper surface of the rail, said piston being capable of inducing the displacement of the liquid piston defined by the crown, when it is activated.

The two windows are located in diametrically opposed positions. The invention can also be applied for cable transport installations such as cable cars and funiculars.

The manner in which the invention may be implemented and the advantages which result therefrom will emerge more clearly from the following exemplary embodiments, given by way of non-limiting indication in support of the appended figures.

Figure 1 is a schematic representation in plan of a rim provided with a tire according to the first embodiment of the invention.

Figure 2 is a representation similar to Figure 1, an intermediate torque transfer wheel.

Figures 3, 4 and 5 are diagrammatic representations in vertical side section of a rim provided with a tire according to that shown in Figure 1, showing three different phases of operation.

Figures 6 and 7 are schematic cross-sectional representations of a variant of the rim of Figures 1 and 3 to 5, Figure 8 a side vertical sectional view.

 Figure 9 is a schematic representation in side vertical section of a wheel provided with a tire for bicycle, Figure 10 a corresponding representation in cross section.

FIGS. 11 and 12 are diagrammatic representations in lateral vertical section of two phases of operation of the wheel acting as an intermediate member for transferring the driving torque, respectively when the latter rotates in the direction of clockwise, and in the trigonometric sense. Figures 13 and 14 are diagrammatic representations in cross section corresponding to two distinct phases of said wheel.

Figures 15 and 16 are diagrammatic cross-sectional representations of a variation of the embodiment shown in Figures 11-14.

Figures 17 and 18 are side vertical sectional representations of a third embodiment of the invention, and relating to a wheel resting on rail, Figure 19 is a cross-sectional view.

FIG. 20 is a cross-sectional view of a wheel for another embodiment of the invention more particularly adapted to a cable car to a funicular, and also being similar to the embodiment described with reference to FIGS. '19.

FIG. 1 shows a schematic representation of a first embodiment of the invention, in which the wheel (1) consists of a rim associated with a tire (2).

There is represented under the reference (4) the bearing surface, said first bearing surface, constituted in this case by road.

According to an essential characteristic of the invention, the tire (2) has on the inner face of its tread, a compressible chamber (3), consisting in this case of two tubes (6, 7) extending collinearly on the along the entire circumference of said tread, in the extension of one another. In other words, they follow the inner circumference of the tread. These tubes, respectively (6) and (7), therefore each extend in a semicircle, and are closed at their two ends, respectively an upstream end (8) and a downstream end (9), the upstream directions and downstream being defined in consideration of the direction of progression of said wheel.

These tubes (6, 7) are made of a flexible but flexible material, on the one hand, to adapt to the shape of the tire, and on the other hand, to allow some compression or compression in the radial direction , without allowing an elongation in the longitudinal direction. On the other hand, they are made of a non-elastic material, such as, as will be shown later, to allow the transmission of a compression, and more precisely the displacement of a liquid piston within them, without generating deformation of the envelope itself. They are typically made of plastic. The downstream end (9) of each of these two tubes further comprises an elastic cushion (1 for example made of elastomer or rubber, the function of which will be described in more detail later This elastic cushion (10) is secured to the inside tube at this downstream end (9).

Each of these two tubes (6) and (7) is filled with an incompressible liquid, and in this case with water, optionally supplemented with antifreeze, in the event that the wheel in question is intended to be used in areas where the temperature is likely to fall below 0 C. This antifreeze has a modulus of elasticity less equal to that of water. In doing so, these two tubes each define a liquid piston, whose envelope is defined by the inner wall of said tubes. FIG. 1 shows a reference frame (0X, OZ), OX corresponding to the horizontal axis or axis of progression of the wheel, and the axis OZ corresponding to the vertical axis passing through the center of the wheel. .

At its zone of contact with the ground (4), the wheel (1) is subjected on the one hand, to the gravitational force of gravitational attraction G, and on the other hand to the reaction R., However, the pneumatic (2) being an elastic medium, it has a radial deformation, and in particular a flattening of the tread, typically over a length lm, which matches the flat shape of the rigid ground, as can be seen on Figures 3 to 5, and corollary, a lateral deformation on either side of this tread.

The rim (1) the wheel is conventionally constituted by a rigid metal structure intended to transmit the forces coming from the axis of the wheel and in particular the driving torque Cl ,,, pneumatic (2), and thus allow to ensure the progression of the vehicle provided with said wheels.

As already stated, according to an essential characteristic of the invention, the inner face of the tread of the tire (2) receives a tube divided into two sections, of substantially equal length, and whose downstream end (9) receives a elastic cushion (10), typically made of elastomer or rubber. This cushion (10) is intended to transform the dynamic force Z, resulting from the compression of the tube itself inducing the progression of the liquid piston that it contains according to its main dimension, and therefore according to the only degree of freedom conferred on it by the relative rigidity of the tube, in a pushing force Zp whose intensity is gradually applied. This cushion is also intended to return said liquid piston in its backward stroke in a very short time. As already said, the water contained in the tubes (6) and (7) is intended to fulfill the role of liquid piston, because of its incompressibility and the rigid nature of the tubes, in order to generate these forces Z and ZP. Of course, the water could be replaced by any other incompressible liquid, but however must be chemically neutral to avoid any reaction with the surrounding material, including the tube and cushion.

Moreover, the volume of water included in each of the tubes (6) and (7) is chosen so as to fill said tube without deforming, in the absence of any external stress, the elastic cushion (9).

According to another characteristic of the invention, the rim (1) comprises pads, also called heels (11), extending substantially radially, and having at their peripheral ends a curved surface (12) tangential to the upstream end, intended to serve as a counter-reaction surface, and located directly above the compression zones, and in this case at the said upstream ends (8) of the tubes (6, 7). These two pads (11) are integral with the rim (1). They are advantageously made of a light but nevertheless resistant material, in order to effectively constitute a counter-reaction surface, and thus to receive charges without being deformed.

In addition, when pneumatic deformations caused by the irregularities of the ground increase sharply, the pad must be able to absorb the shock by its elastic deformation. In the event of a puncture, the pad must yield by a controlled break by reducing its section in a specific place so that the debris remain inside the tire.

It will be briefly described the operation of this pneumatic wheel according to the invention.

As already stated, the axis on which the wheel (1) is mounted is connected to a motor, which thus prints the wheel with a driving torque C "n, the tread thus constitutes an elastic medium which, when flattens out due to the support of the wheel on the rigid ground, bears against the surface (12) of the counter-reaction shoe (11) when it is located in line with the ground; say, once per turn for each of the tubes (6, 7), which then causes the tube (6, 7) to be compressed at the upstream end (8), and hence the displacement of the liquid piston, as well as this appears in Figure 4. However, when the pad (11) is not located in line with the contact zone of the wheel on the ground, there is no compression of the tube, the latter the simple deformation of the tire tread Because of the constitution and the nature of the tube in question, having in particular no elasticity this compression induces the displacement the liquid piston at the other end, that is to say at the downstream end (9) of the tube, substantially diametrically opposite. This liquid piston thus abuts against the elastic cushion (10) integral with said downstream end.

This compression of the elastic cushion is inherent to the single degree of freedom enjoyed by the liquid piston, and in fact confers a discontinuity effect of the elastic medium in the tire, since said cushion has practically no resistance to the liquid piston. Thus, when the wheel rolls on the rigid ground between two discontinuities of medium, the opposing forces G and its reaction R ,, are in a state of static equilibrium on the vertical. On the other hand, when a discontinuity of elastic medium appears direct contact with the rigid ground, the two antagonistic forces G and R, then become a system of dynamic forces generating a dynamic force Z. This dynamic force Z is at its quasi-tangent birth on the ground. It is carried by the liquid piston along its half-circumference to the downstream end (9) which is diametrically opposite. At this level, it compresses the elastic cushion (1 located at the downstream end, and then behaves like a ZP thrust force and becomes again parallel to the ground, giving the wheel a maximum moment of reversal MR with respect to its point of support O on the rigid ground.

This maximum reversal moment MR is expressed in particular by the following relation MR = ZP xd ,, where dEF is the effective diameter of the wheel, ie the wheel diameter in the absence of any constraint and therefore of any zone flattened.

This maximum reversal moment generates an additional engine torque Cz whose value is determined by the following relationship CZP = ZP x dg. This torque is added to the engine torque Cp and is oriented in the same direction as this one.

The calculations show that for the same amount of mechanical energy consumed, the mechanical energy supplied to the vehicle by the two driving couples simultaneously is likely to increase by a factor of 45%. As a result, this increase in mechanical energy transmission efficiency leads to a reduction in pollution and consumption. As already mentioned above, FIGS. 3 to 5 represent three stages of the mode of operation of the pneumatic wheel according to the invention, respectively before the cooperation of the upstream zone of the tube with the ground, during, and after.

FIGS. 6 and 7 show a variant of the pneumatic wheel in which the tread does not receive a clearance but two sets of two tubes. These sets of tubes are therefore positioned against the inner face of the tread, and symmetrically to each other with respect to the vertical plane of symmetry passing through OZ. More specifically, it comprises two sets of two tubes, each of the tubes extending, as in the previous example in a semicircle. In order to optimize the operation of this embodiment, the rim receives four counter-reaction pads (11), respectively two for each series of tubes, the pads of a series of tubes being offset by 90 relative to those of the other series, as it appears very clearly in Figure 10, and also, the respective ends of the tubes being themselves offset by 90 of a game relative to each other.

FIG. 6 shows the wheel in cross section, in the situation where the feedback shoe (11) is located at the contact zone of the wheel on the ground. This figure also shows, first of all, the compression of one of the tubes of the first set of tubes, that of the right in this case, and in parallel, the non-compression of the second tube of the same set by the symmetrical pad, located then at the top of the wheel. In contrast, the second set of tubes undergoes no compression, said pads being substantially in a horizontal position at this time.

In contrast, Figure 7, which also represents the wheel in cross section, but after a quarter turn, the situation is reversed. Indeed, the first set of tubes is no longer subjected to compression, since the two corresponding pads are substantially in a horizontal position. On the other hand, one of said tubes of the second game undergoes compression, while the other located at the top, does not suffer.

In this way, the operation of the device is optimized by increasing the frequency of the implementation of the pushing forces ZP. Figures 9 and 10 show the particular application of the invention a bicycle wheel. The principle remains exactly the same, only the dimensioning of the elements being modified.

In another embodiment of the invention, more particularly described with reference to FIGS. 2 and 11 to 14, the wheel in question is a wheel provided at its periphery with a closed annular groove (13). This groove is in fact made up of two independent collinear sections, having at one of their ends a window (14) opening towards the outside. The two windows (14) of the two groove sections (13) are diametrically opposed.

The two windows (14) are further closed by an elastic membrane (15), as can be seen in connection with Figures 11 to 14, and are intended to cooperate with a movable wall, typically constituted by a rotating roller (16), or even by a belt (17) mounted between two idler rollers (18).

The two sections are intended to be filled with an incompressible liquid and in particular water. These two sections are separated from each other, at each of their two ends, by a disc valve (26), pivotable about an axis (29) extending diametrically with respect to said groove (13). ). One of the faces of this valve receives an elastic cushion (10), for example of hemispherical shape. However, preferably, this elastic cushion (10) is replaced by an elastic membrane (30) mounted on the periphery of a rigid perforated metal mesh (31) of circular shape, whose diameter substantially corresponds to the diameter of the throat (13). The elasticity of the membrane plays the same role as that of the cushion (10).

 Thus, when the wheel rotates in the direction of clockwise, as shown in Figure 11, the liquid piston in each of the two sections thus defined, also moves in the same direction. The disc valve (26) is positioned so that the elastic membrane (30) is located at the downstream end of each of the sections. This membrane (30) is located downstream of the lattice (31), as can be seen in the bottom right in FIG. 11. It swells under the effect of the liquid passing through the perforated lattice (31), up to the limit of its elasticity. In contrast, the membrane (30) is located to the right of the lattice (31) at the valve on the top left of the same FIG. 11. Under the effect of the compression generated in the zone immediately adjacent to this valve, said membrane is pressed against the lattice (31), thereby preventing the displacement of the liquid piston in this direction. On the other hand, as soon as the wheel rotates the other direction (see FIG. 12), the two valves are printed with a rotation of 180 by means of the pivot axis (29), to which a handling device (32) is advantageously secured. ), adapted to allow this maneuver, so as to reverse the positioning of the elastic cushion, or the membrane, so that it or it is actually found at the downstream end of said sections.

In a variant of this embodiment, the zones of the grooves located in the vicinity of the windows (14) are provided with not one, but two pivoting disc valves, of the type previously described. As can be seen in Figures 11 and 12, these valves (26, 26 ') are located on either side of said window, substantially in the vicinity of the compressible zone.

In this way, when the wheel (1) is rotated in a clockwise direction, as already mentioned, the valve at the top left is closed, and closes the groove (13), the elastic membrane ( 30) being then located to the right of the perforated lattice (31), according to the configuration described in FIG. 11. As a corollary, the valve at the top right (26 ') is open, that is oriented substantially at 90 relative to the plane defined by the left valve (26). In this configuration, it does not oppose the displacement of the liquid piston located in the straight section, generated by the compression of the diaphragm (15), when that comes directly above the roller (16) or the belt (17). ), the membrane (31) which it bears being pressed against the lattice (31) by the elastic effect of the material constituting it. It is then the valve (26) in the lower right which plays the role, as already described elastic cushion.

On the other hand, since the direction of rotation of the wheel is reversed (see FIG. 12), the valve at the top right (26 ') is in turn closed, taking care to position the elastic membrane (30) on the left with respect to the lattice (31), given the configuration described, and the valve at the top left (26) is open, allowing the free movement of the liquid piston located in the left section.

It is then the valve at the bottom left (26 ') which plays the role of elastic cushion.

The implementation of two sets of two disc valves optimizes the action of the liquid piston, given the angle of attack of the thrust force. Moreover, it makes it possible very quickly to modify, by means of the handling device (32), the direction of operation of the liquid pistons, as a function of the direction of rotation of the wheel. The movable wall (16, 17) is intended to fulfill strictly the same role as the ground in the example of the wheel provided with a tire. In other words, it acts according to a compression effect to generate the crushing of the membrane (15) and, consequently, the displacement of the liquid piston within the considered section of the peripheral groove and thus, to generate a force quasi-tangent to this periphery.

 Thus, when the membrane is in contact with one of the moving walls, the liquid in this case water, is compressed with a compressive force Fc inducing the birth of a force Z which starts perpendicular to the axis OZ.

This force is then conveyed by the liquid piston along its half circumference to the other end, in particular the downstream end, diametrically opposite.

At this level it compresses the elastic cushion (10) secured to the valve (26) and behaves like a thrust force Zp which becomes perpendicular to the axis OZ again according to FIG. 2. It thus gives the wheel another engine torque CZp, oriented in the same direction as the engine torque C. imparted to the wheel is motor axis or by any other means.

The calculations carried out in relation with this embodiment make it possible to demonstrate an increase in the transmission efficiency of the mechanical energy consumed of the order of 42%.

This increase in efficiency allows considerable savings in energy consumption, and consequently the resulting manufacturing costs are also greatly reduced.

FIGS. 15 and 16 show a variant of this embodiment, in which the periphery of the wheel comprises not one but two full grooves, and more specifically two sets of two throat sections, situated on the same surface. peripheral curve, and whose opening windows (14) are offset by 90 relative to each other, so as to confer maximum efficiency to the device according to the invention. Of course, the respective ends of throat sections are also shifted by 90. FIGS. 16 to 19 show a particular embodiment of the invention applied to wheels intended to rest on rails.

The rail is schematically represented by the reference (21). These wheels typically have a side wall (20), intended to bear against the (21), to avoid derailment.

Each wheel has, in the vicinity of its periphery, two annular closed rings (19), for example by means of a discoid valve of the type referred to under reference (26) in FIGS. 11 and 12, said rings being positioned in the extension of one another, and having at their downstream end an elastic cushion (10). The upstream end of each of said grooves opens towards the outside by a window (25), closable by a piston (22). In order to avoid any risk of locking the piston during its stroke, its free end is provided with a ball (24) mounted freely in rotation within a cavity provided for this purpose in the head of said piston. This ball (24) is able to bear against the upper surface of the rail (21). Moreover, in the absence of any external stress, a spring (23) or any other equivalent system, induces the thrust of the piston and the ball (24) radially outwardly. The piston (22) thus ensures sealing of said rings. These are in fact filled with water, and each defines a liquid piston, like the previous description in connection with the other embodiments of the invention.

On the other hand, when the ball (24) comes into contact with the rail (21), it causes the lowering of the piston (22) locally within the upstream end of the ring in question, and consequently the displacement of the corresponding liquid piston. within this ring, inducing a dynamic effect equivalent if not identical to that described in connection with the two previous embodiments.

The variants described with reference to FIGS. 11 and 12, implementing instead of the elastic cushion (10) an assembly constituted by an elastic membrane (30) and a perforated metal mesh (31) applies in the same way , and allow, as already indicated, to very easily change the direction of the point of application of the liquid pistons, depending on the direction of rotation of the wheels. In a variant of this embodiment, more particularly adapted to cable transport, such as cable cars and funiculars, in which the transport member rests on a carrying cable (27) by a pulley (1) provided at its periphery with a groove (28), the same assembly as that described above can be resumed (see Figure 1) again the embodiments described in connection with Figures 1 and 12, implementing instead of the elastic cushion (10) an assembly constituted by an elastic membrane (30) and a perforated metal lattice (31) are also applicable.

It is therefore conceivable the interest of the device according to the invention, in connection with either a significant increase in efficiency, or even very significant energy savings, in addition to a reduction in pollution.

This device is transposable to all types of wheel, whether it is driving or free.

Claims (14)

Wheel for transmitting an engine torque, <I> characterized </ I> in that it is provided in the vicinity of its circumference with at least one compressible chamber filled with an incompressible liquid, thereby defining a liquid piston, said chamber being intended to generate an additional torque, oriented in the same direction as the engine torque, and cooperating directly or indirectly with a fixed or movable support surface, said first bearing surface, resulting in the compression of said compressible chamber and corollary by the displacement of the liquid piston in a single degree of freedom. 2. Wheel (1) according to claim 1, provided with a tire <I> (2) </ I> characterized in that # the compressible chamber (3) consists of at least two flexible tubes (6, 7 ) integral the inner wall of the tread of said tire (2), positioned in the extension of one another so as to extend over the entire inner circumference of said tire, each of these tubes being filled with an incompressible liquid and being closed at its two ends respectively an upstream end (8) and a downstream end (9), the downstream end of said tubes receiving an elastic cushion (10) secured to the tube at this level, # and in that the wheel (1) is provided at right angles to the upstream end (8) of each of said tubes (6, 7) with a fixed and rigid radial pad (11), which is also capable of constituting a bearing face and counter-reaction for each of said tubes, when it cooperates with the first bearing surface, constituted p by the ground. 3. Wheel according to claim 2, characterized in that the compressible chamber (3) consists of two or more sets of tubes mounted on the same curved surface of the tread and thus secured to the internal face thereof. 4. Wheel according to one of claims 2 and 3, characterized in that the elastic cushion (10) is made of rubber or elastomer. 5. Wheel according to claim 1, characterized in that the compressible chamber is constituted by a groove or peripheral ring (13) comprising two collinear and independent sections, and extending substantially in two half-circles. each of said sections being filled with an incompressible liquid and being closed at its two ends, respectively an upstream end and a downstream end, and being defined by a rigid cylindrical wall over its entire circumference with the exception of at least an outwardly directed window (14) positioned opposite the upstream end, said window constituting the zone of cooperation with the first bearing surface, at which it is closed by a flexible membrane (15), said windows being positioned diametrically in relation to one another, and the downstream end of each of the sections receiving an elastic cushion (10). Wheel according to Claim 5, characterized in that the bearing surface is constituted by an idler roller (16) or a belt (17) mounted between two idle rollers (18). . 7. Wheel according to claim 1, intended to roll on a rail, <I> characterized </ I> in that compressible chamber (3) consists of two collinear peripheral annular rings (19), independent of one of the another, filled with an incompressible liquid, the two crowns each having an upstream end and a downstream end, the latter receiving a lactic cushion (10), the upstream end of each of the rings being provided with a through window directed towards outside, and closed by means of a piston (22) radial stroke, said piston (22) being capable of inducing the displacement of the liquid piston defined the ring (19), when activated, it is to say when it cooperates with the upper surface of the rail (21), said windows being located in diametrically opposed positions. 8. Wheel according to claim 7, characterized in that the piston head (22) is provided with a ball (24) intended to cooperate with the upper surface of the rail (21). 9. Wheel according to claim 1, intended to roll on a carrying cable, <I> characterized </ I> that the compressible chamber (3) consists of collinear peripheral annular rings (19), independent of one of the other, filled with an incompressible liquid, the two rings each having upstream end and a downstream end, the latter receiving an elastic cushion (10), the upstream end of each of the rings being provided with a through window directed towards the outside, and closed by means of a piston (22) radial stroke, said piston (22) being capable of inducing the displacement of the liquid piston defined by the ring (19), when activated, it is at say when it cooperates with the upper surface of the cable (27), said windows being located in diametrically opposed positions. 10. Wheel according to claim 9, characterized in that the piston head (22) provided with a ball (24) intended to cooperate with the upper surface of the wheat (27). 11. Wheel according to one of claims 5 to 10 characterized in that the sections formed in the groove or peripheral ring (13, 19) are defined by means of two disc valves (26), pivotable along a diametrical axis (29) with respect to said groove respectively to said ring, so as to be able to close said groove, respectively said ring, one of the faces of said valves receiving an elastic cushion (10). Wheel according to claim 11, characterized in that the groove (13) and the crown (19) respectively receive two sets of two disc valves (26, 26 '), each set (26, 26). ') being positioned on either side of the window (14), one of the valves of each of the games being in the closed position, suitable for closing the groove (1 while the other is in the open position, and vice versa. 13. Wheel according to one of claims 11 and <I> 12, characterized </ I> in that the disc valves are constituted by a rigid perforated circular lattice (31), of diameter corresponding substantially to the diameter of the groove, respectively the ring, on the periphery of which is secured a resilient membrane (30) susceptible under the action of the liquid piston contained in said groove or ring, or to be pressed against said mesh, and then to form an end, and in particular an upstream end for said liquid piston, or to swell under the action of said liquid piston, slightly away from the lattice (31), so as to act as an elastic cushion, and then constituting the downstream end said liquid piston. 14. Wheel according to one of claims 1 to 13, characterized in that incompressible liquid is constituted by water.