Crankshaft roller skates for better stability

Abstract

The invention relates to a roller skate (100) comprising a foot support (110), two front wheels (140.1; 141.1) and two rear wheels (140.2; 141.2), a first crankshaft (120.1) providing a connection between the front wheels and the foot support and a second crankshaft (120.2) providing a connection between the rear wheels and the foot support. Each crankshaft comprises a central element defining a central axis, a first lateral element defining a first axis of rotation of a left wheel and a second lateral element defining a second axis of rotation of a right wheel, a first arm connecting the central element to the first lateral element and a second arm connecting the central element to the second lateral element. For each of the first and second crankshafts, the first arm and the second arm form an angle around the central axis strictly less than 180°, and greater than or equal to 90°. FIG. 1

Description

Title of the invention: Roller skate with crankshafts allowing better stability

[0001] The present invention belongs to the field of roller skates.

[0002] It is particularly advantageous when roller skates are used on rough roads or on bends.

[0003] Roller skates of the inline roller skate type are known, comprising a foot support below which several wheels, for example four wheels, are arranged in series. Thus, the size of the wheels is limited so that the user's foot is not too high, which would create a risk of falls for the user.

[0004] Such skates also have the disadvantage of allowing significant angles of inclination when turning, which can cause pain, or even injury, to the user's ankle.

[0005] There is therefore a need to improve the stability, safety and skating comfort of roller skates, as well as to enable the integration of larger wheels than in prior art solutions of the inline roller skate type.

[0006] The present invention improves the situation.

[0007] To this end, a first aspect of the invention relates to a roller skate comprising a foot support, two front wheels and two rear wheels, a first crankshaft providing a junction between the two front wheels and the foot support and a second crankshaft providing a junction between the two rear wheels and the foot support, in which each of the first and second crankshafts comprises a central element defining a central axis, a first lateral element defining a first axis of rotation of a left wheel and a second lateral element defining a second axis of rotation of a right wheel, a first arm connecting the central element to the first lateral element and a second arm connecting the central element to the second lateral element. For each of the first and second crankshafts, the first arm and the second arm form an angle around the central axis, the angle being strictly less than 180°, and greater than or equal to 90°.

[0008] The invention makes it possible to lower the central element relative to the axes of rotation of the wheels, thus lowering the position of the user's foot. This results in a distance of the foot closer to the ground, with smaller angles of inclination than in the solutions of the prior art, leading to less stress on the ankle. In addition, such a shape makes it possible to promote cushioning in the event of uneven roads. or variation of the user's support. Skating comfort is thus significantly improved compared to roller skates according to the prior art.

[0009] According to one embodiment, for each of the first and second crankshafts, the angle may be between 130° and 170°, preferably between 130° and 160°, in particular between 140° and 150°.

[0010] The angle is thus optimized to facilitate the recovery of support when exiting a bend and to lower the position of the user's foot. The comfort and safety associated with skating are thus improved.

[0011] According to one embodiment, a skating direction defines a vertical plane normal to the skating direction, contact points of the four wheels on the ground define a mean contact plane, and for at least one of the first and second crankshafts, the projection of the first wheel rotation axis in the vertical plane and / or the projection of the second wheel rotation axis in the vertical plane is inclined by a camber angle relative to the projection of the central axis of the crankshaft in the vertical plane of the roller skate, when respective intersections of wheel planes with the mean contact plane are parallel to each other and to the skating direction.

[0012] In this way, when the roller skate is flat, the inclination of the rotation axes on one of the crankshafts allows the roller skate to move in a straight line in the skating direction. Furthermore, when the user tilts the foot support, the rotation planes of the wheels with the camber angles, rotating around the central axis of the crankshaft, tilt and make the wheels steerable, thus allowing a curved trajectory of the roller skate.

[0013] It is thus made possible to alternate between straight and curved trajectories depending on the user's pressure on the foot support.

[0014] According to one embodiment, for each of the first and second crankshafts, the first and second crankshafts may have a size greater than a width of the foot support, so that the wheels are positioned on either side of the foot support.

[0015] It is thus made possible to increase the size of the wheels while bringing the user's foot closer to the ground.

[0016] According to one embodiment, for at least one of the first and second crankshafts, the central element may be capable of varying the angle between the first arm and the second arm.

[0017] Thus, the crankshaft is able to absorb variations in the user's support or shocks caused by irregularities on the road.

[0018] In addition, the central element:

[0019] - may be made of a torsionally flexible material, for example spring steel;

[0020] - may include a central zone of smaller section than lateral zones right and left of the central element; or

[0021] - may comprise a right piece, a left piece and a central piece, the piece central being able to allow rotation of the left part relative to the right part.

[0022] Thus, the insertion of such an elastic element on the central element makes it possible to produce a suspension without requiring a complex device.

[0023] Additionally or alternatively, the roller skate may further comprise a return spring placed between one of the first and second crankshafts and the support, and capable of exerting a return torque between the crankshaft and the support.

[0024] The restoring torque may be zero in a defined position and increase when the central axis of the crankshaft rotates in one direction or the other. The law of evolution of the restoring torque in one direction of rotation may be different from the law of evolution of the restoring torque in the other direction. Indeed, the restoring torque may be adapted to the moment of inertia of the assembly formed by a lateral element and the wheel associated with it. The length of the lateral elements are not necessarily equal, nor are the respective sizes of the wheels.

[0025] It is thus made possible to reposition the crankshaft during skating before the user places the roller skate back on the ground. Skating comfort and stability are thus improved.

[0026] According to one embodiment, for at least one of the first and second crankshafts, the first and second arms may be made of magnesium and aluminum alloy or of a composite material of carbon fiber and polymer resin.

[0027] Thus, the strength of the crankshaft is improved, particularly at the level of the arms which undergo significant torsion, bending, traction or compression forces.

[0028] According to one embodiment, the roller skate may comprise at least two stops capable of constraining the rotation of at least one of the first and second crankshafts around the central axis of the crankshaft, so that each lateral element associated with a wheel whose axis of rotation is located under the central axis of the crankshaft is always in the same half-space delimited by a plane normal to the skating direction and containing the central axis of the crankshaft. The right and left stops are such that the right and left lateral elements of the same crankshaft are included in different half-spaces.

[0029] Such stops make it possible to limit the rotation of the crankshaft in a range of angles in which the central element remains lower than the axes of rotation of the wheels, in particular when the wheels of the skate are put back into contact with the ground.

[0030] They thus prevent the crankshaft from adopting an inverted position which would be unstable. The stability associated with slippage is thus improved.

[0031] According to one embodiment, a pivot connection between the foot support and at least one of the first and second crankshafts is capable of slowing the rotation of the central element of the crankshaft relative to the foot support.

[0032] Such a slowing down function makes it possible, after pressing, to maintain the position of the wheels for a few moments, which limits the risk of skidding when the skate is lifted off the ground by the user.

[0033] According to one embodiment, for at least one of the first and second crankshafts, the first arm and the second arm may have different longitudinal sizes, the arm directed forward in a skating direction of the roller skate being shorter than the arm directed backward in the skating direction.

[0034] This embodiment makes it possible to reduce the mass of the crankshaft, since it takes into account the fact that the arm directed forward in the direction of slippage is subjected to compression-buckling while the other arm directed backward in the direction of slippage is subjected to traction.

[0035] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings in which:

[0036] [Fig-1] shows a side view of a roller skate according to one embodiment of the invention;

[0037] [Fig.2a] shows a crankshaft of a roller skate according to an embodiment of the invention;

[0038] [Fig.2b] shows a side view of the crankshaft of [Fig.2a], in a plane perpendicular to the central axis of the crankshaft;

[0039] [Fig.3] illustrates a central crankshaft element of a roller skate according to one embodiment of the invention;

[0040] [Fig.4a] illustrates a front view oriented from front to rear of the roller skate in a plane perpendicular to the skating direction, according to an embodiment of the invention;

[0041] [Fig.4b] shows a view similar to that of [Fig.4a] of a roller skate according to another embodiment of the invention;

[0042] [Fig.5a] illustrates a top view of the roller skate according to an embodiment of the invention, in a plane parallel to a road on which the roller skate is traveling;

[0043] [Fig.5b] illustrates a side view of a stop in the same plane perpendicular to the central axis as in [Fig.2a].

[0044] [Fig.l] shows a side view of a roller skate 100 according to one embodiment of the invention.

[0045] The roller skate 100 includes a foot support 110 adapted to support a foot of a user of the roller skate 100. The foot support 110 may further include a means for attaching the roller skate 100 to the user's foot, not shown in [Fig. 1]. The foot support 110 may thus have the dimension of a foot of a given size. No restriction is attached to the material used for the foot support 110.

[0046] The roller skate 100 further comprises:

[0047] - a first crankshaft 120.1 providing a junction between the foot support 110, a 140.1 left front wheel and a 141.1 right front wheel; and

[0048] - a second crankshaft 120.2 providing a junction between the foot support 110, a 140.2 left rear wheel and a 141.2 right rear wheel.

[0049] The contact points of the wheels on the ground define a plane 150, called the mean contact plane in the following. A vertical plane 160 is also defined, normal to the front-rear axis of the roller skate, therefore normal to a skating direction 170. The intersection of the planes 150 and 160 forms a left-right axis of the roller skate 100, not visible in the figure because it is normal to the section plane. The vertical plane 160 may in particular delimit a front part of the roller skate from a rear part.

[0050] The roller skate 100 further comprises a first attachment element 130.1 of the first crankshaft 120.1 to the foot support 110.

[0051] No restriction is attached to the fixing elements 130.1 and 130.2 which may be mechanical elements integral with the foot support 110 and which may provide a pivot connection, or sliding pivot, with the crankshafts 120.1 and 120.2.

[0052] The first and second crankshafts according to the invention are as illustrated in Figures 2a and 2b.

[0053] [Fig.2a] shows a crankshaft 120 according to one embodiment of the invention. The crankshaft 120 comprises:

[0054] - a central element 201 defining a central axis 210, or axis of rotation of the crankshaft 120. The central element 201 is in particular in pivot connection with the foot support 110, for example via the fixing elements 130.1 and 130.2 discussed above. Such a pivot connection can perform a function of slowing down the rotation of the central element 201. Such slowing down makes it possible, after a press, to maintain the position of the wheels for a few moments, which allows the user to avoid skidding. No restriction is attached to the manner in which the slowing down function is performed. For example, the foot support can be shaped so that the pivot connection is tight and provides friction having the effect of slowing down the rotation of the crankshaft. Such a central element generally comprises a right bearing, a left bearing as well as a connecting element between the right and left bearings;

[0055] - a first lateral element 202.1 defining a first wheel rotation axis 211.1. The first lateral element may correspond to a crank pin;

[0056] - a second lateral element 202.2 defining a second wheel rotation axis 211.2. The second lateral element can also correspond to a crank pin;

[0057] - a first arm 203.1 connecting the central element 201 to the first lateral element 202.1; and

[0058] - a second arm 203.2 connecting the central element 201 to the second lateral element 202.2.

[0059] The first and second arms 203.1 and 203.2 may also be referred to as cranks.

[0060] The central element 201, the first lateral element 202.1, the second lateral element 202.2, the first arm 203.1 and the second arm 203.2 may be a single piece, or may be separate pieces, assembled by means not shown in the figures.

[0061] The projections of the central axis 210 and the wheel rotation axes 211.1 and 211.2 into the mean contact plane 150 are parallel, when respective intersections of wheel planes with the mean contact plane are parallel to each other and parallel to the direction of slippage.

[0062] Furthermore, in the embodiment of [Fig.2a], the projections of the central axis 210 and the wheel rotation axes 211.1 and 211.2 in the vertical plane 160 are parallel to each other, when respective intersections of wheel planes with the mean contact plane are parallel to each other and parallel to the skating direction. This is however not the case in the embodiment of FIG. 6, as described later.

[0063] In [Fig.2a], the arms 203.1 and 203.2 are arranged perpendicular to the central element 201 and to the lateral elements 202.1 and 202.2. However, no restriction is attached to the shape and arrangement of the arms 203.1 and 203.2 which, alternatively, may be oblique.

[0064] [Fig.2b] shows a side view of the crankshaft 120, in a plane perpendicular to the central axis 210 of the crankshaft.

[0065] [Fig.2b] illustrates in particular an angle 220 formed by the first arm 203.1 and the second arm 203.2. The angle 220 corresponds more precisely to the angle of the projections of the first and second arms 203.1 and 203.2 in the plane perpendicular to the central axis 210. According to the invention, the angle 220 is strictly less than 180° and greater than or equal to 90°.

[0066] In particular, the angle 220 may be between 130° and 170°, preferably between 130° and 160°, in particular between 140° and 150°. An angle of approximately 145° is optimal.

[0067] Thus, as illustrated in [Fig.2b] and in [Fig.l], the central element 201 is lower than the wheel rotation axes 211.1 and 211.2, which makes it possible to bring the user's foot from the ground and allows for reducing the angles of inclination of the foot support when turning. The angle of inclination of the foot support may in particular be less than 30 or 40°, which induces less stress on the user's ankle compared to the solutions of the prior art. The angle of inclination corresponds to the angle of rotation of the foot support around a front-rear axis of the roller skate.

[0068] Furthermore, when exiting a bend, such an angle 220 makes it possible to facilitate the transition between an inclined position of the foot support and a straight, flat position (parallel to the mean contact plane 150).

[0069] In particular, the closer the angle 220 is to 90°, the lower the effort required to move from an inclined position to an upright position.

[0070] As indicated in [Fig.2b] by the two double arrows on either side of the crankshaft 120, the angle 220 can be variable. For this purpose, the central element 201 can be capable of varying the angle 210 between the first arm 203.1 and the second arm 203.2. The central element 201 is thus used as a torsion shaft. For example, the central element 201:

[0071] - is made of a material that is flexible in torsion, for example spring steel. By “torsional flexibility” means a material that exhibits torsional elasticity greater than a predefined threshold;

[0072] - includes a central zone of smaller section than the right side zones and left of the central element 201. For example, the central area may be hollow or flattened and the side areas tubular. This embodiment may be combined with the first embodiment, i.e. with a central element 201 made of a flexible material; or

[0073] - comprises a right piece, a left piece and a central piece, the central piece being capable of allowing rotation of the left part relative to the right part, as illustrated in [Fig.3].

[0074] The variation of the angle 220 by the central element 201 advantageously makes it possible to improve the suspension of the roller skate 100, and therefore the skating comfort, in particular when the road on which the roller skate 100 is traveling is degraded.

[0075] [Fig.3] illustrates the central element 201 of a crankshaft 120 according to an embodiment of the invention.

[0076] The central element 201 comprises a left part 301.1, a right part 301.2 and a central part 300. As indicated above, the central part may be capable of allowing rotation of the left part 301.1 relative to the right part 301.2. No restriction is attached to the production of such a double pivot connection. Shock absorption on a degraded road is thus improved.

[0077] The central element 201 may further comprise a return spring 302 arranged between the foot support 110 and the central element 201 and capable of exerting a return torque on the central element 201, the return torque being cancelled when an angle between the first arm and the second arm is equal to an equilibrium angle.

[0078] The restoring torque may be zero in a defined position, corresponding to the equilibrium angle, and increase when the central axis 210 of the crankshaft 120 rotates in one direction or the other. The law of evolution of the restoring torque in one direction of rotation may be different from the law of evolution of the restoring torque in the other direction. Indeed, the restoring torque may be adapted to the moment of inertia of the assembly formed by a lateral element and the wheel associated with it. The respective lengths of the lateral elements are not necessarily equal, nor are the respective sizes of the wheels.

[0079] For example in [Fig.3], two return springs 302 are connected to the foot support 110, not shown in the figure, on the one hand, and to the left part 301.1 and right part 301.2, on the other hand.

[0080] Such a return spring 302 may also be placed between the foot support 110 and a central element 201 according to embodiments other than the embodiment of [Fig. 3]. For example, such springs may be provided when the central element 201 is made of a flexible material and / or when the central element 201 comprises a central area of smaller section than right and left lateral areas of the central element 201.

[0081] The use of a return spring advantageously makes it possible to rest the roller skate 100 flat, after having raised the skate from the ground. Thus, it improves the positioning of the roller skate 100 on the road and consequently the comfort associated with skating.

[0082] The arms 203.1 and 203.2 and the lateral elements 202.1 and 202.2 of the crankshaft 120 may be made of the same material as the central element 201. Alternatively, at least one of the arms 203.1 and 203.2 and the lateral elements 202.1 and 202.2 are made of a different material from the central element 201.

[0083] In particular, the arms 203.1 and 203.2 may be made of a more rigid material. than the flexible material of the central element 201. The arms 203.1 and 203.2 may for example be made of magnesium and aluminum alloy or of a composite material of carbon fiber and polymer resin.

[0084] The arms 203.1 and 203.2 may have an equal length. Alternatively, they may have different lengths. In particular, the first arm 203.1 extends mainly forward in the skating direction while the second arm 203.2 extends mainly rearward in the skating direction, as can be seen in particular in [Fig.l].

[0085] One of the arms is therefore subjected to traction while the other arm is subjected to compression. The first arm 203.1 is in front, and therefore undergoes a compression-buckling force from the central element 201 connected to the foot support 110, while the second arm 203.2, which is at the rear, undergoes a traction force from the central element 201. The arm in traction, i.e. the second arm 203.2, is advantageously longer than the arm in compression-buckling, i.e. the first arm 203.1.

[0086] [Fig.4a] illustrates a front view oriented from front to rear of the roller skate 100 in the vertical plane 160 perpendicular to the skating direction, according to an embodiment of the invention.

[0087] [Fig.4a] indicates in particular that the central element 201 is lower than the wheel rotation axes 211.1 and 211.2.

[0088] Furthermore, as can be seen in [Fig.4a], a length 400 of the crankshafts 120.1 and 102.2 is greater than a width 401 of the foot support. Thus, the wheels 140.1, 140.2, 141.1 and 141.2 are located on either side of the user's foot. It is thus possible to have large wheels while having a low center of gravity for the roller skate 100.

[0089] [Fig.4b] shows a view similar to that of [Fig.4a] of a roller skate 100 according to another embodiment of the invention.

[0090] In [Fig.4b], only the front part of the roller skate 100 is shown. will understand that the characteristics which apply to the first crankshaft 120.1 illustrated in [Fig.4b], can also apply to the second crankshaft 120.2 introduced previously.

[0091] According to the embodiment of [Fig.4b], the first crankshaft 120.1 comprises camber angles 610.1 and 610.2.

[0092] A first camber angle 610.1 corresponds to the angle between the projection of the first wheel rotation axis in the vertical plane 160 and the projection of the central axis 210 in this same vertical plane 160, when the intersections of the planes of the wheels and the mean contact plane 150 are parallel to each other. The first camber angle 610.1 also corresponds to the angle between a straight line 601.1 normal to the mean contact plane 150 and passing through the center of the left front wheel, and a straight line 600.1 passing through the center of the left front wheel and the contact point of the left front wheel, when the intersections of the planes of the wheels and the mean contact plane are parallel to each other and parallel to the slip direction 170.

[0093] A second camber angle 610.2 corresponds to the angle between the projection of the second wheel rotation axis 211.1 in the vertical plane 160 and the projection of the central axis 210 in this same vertical plane 160, when the respective intersections the planes of the four wheels and the mean contact plane 150 are parallel to each other and parallel to the direction of slippage 170.

[0094] The second camber angle 610.2 also corresponds to the angle between a straight line 601.2 normal to the mean contact plane 150 and passing through the center of the right front wheel, and a straight line 600.2 passing through the center of the right front wheel and the point of contact of the right front wheel with the mean contact plane 150, when the respective intersections of the planes of the four wheels and the mean contact plane 150 are parallel to each other and parallel to the direction of slip 170.

[0095] The first and second camber angles 610.1 and 610.2 may have the same value. Alternatively, the camber angles 610.1 and 610.2 may be different.

[0096] No restriction is attached to the number of non-zero camber angles on the four wheels of the roller skate 100 according to this embodiment of the invention. According to a preferred embodiment, the same non-zero camber angle can in particular be applied to the two front wheels of the roller skate 100 and the same non-zero angle in the opposite direction to the two rear wheels.

[0097] The manufacture of the first and second crankshafts 120.1 and 120.2 is then advantageously simplified since the first and second crankshafts are then identical, only their respective arrangements relative to the foot support 110 being reversed. They are thus mounted differently (the second crankshaft is positioned by rotating the front crankshaft 180° around a vertical axis), but manufactured in the same way.

[0098] Due to the unaffected camber angles, when the roller skate is flat, the inclination of the rotation axes on one of the crankshafts allows the roller skate 100 to travel in a straight line in the skating direction 170. However, when the user tilts the foot support 110, the rotation planes of the wheels with the camber angles, rotating around the central axis of the crankshaft, tilt and make the wheels steerable, thus allowing a curved trajectory of the roller skate 100.

[0099] It is thus made possible to alternate between straight and curved trajectories depending on the user's pressure on the foot support 110.

[0100] Facilitating the curved trajectories of the roller skate 100 is particularly advantageous for speed racing applications on a curved track or for slalom between cones or for use on a pedestrian sidewalk. The camber angles can thus be determined, or even adjusted, according to the radius of curvature of a track. Maintaining the trajectory by a user of the roller skate 100 is thus greatly facilitated.

[0101] The camber angles are advantageously strictly greater than 0° and less than or equal to 10°. In particular, for track applications, the camber angles may be strictly greater than 0° and less than or equal to 1°. For use on a sidewalk, the camber angles may be between 2.5 and 3.5°, which corresponds to radii of curvature between 2m and 2.50m.

[0102] [Fig.5a] illustrates a top view of the roller skate 100 according to an embodiment of the invention, in a plane parallel to the mean contact plane 150.

[0103] In order to simplify the description, only the front part of the roller skate 100 is shown in [Fig.5a].

[0104] The roller skate 100 may further comprise a left front stop 500.1 and a right front stop 500.2, which are capable of constraining the rotation of the first crankshaft 120.1, around its central axis 210.

[0105] In particular, the left front stop 500.1 is capable of limiting the rotation of the left part of the first crankshaft 120.1 comprising the first arm 203.1 and the first lateral element 202.1. For this purpose, the left front stop 500.1 can be arranged to come into abutment on the first arm 203.1 between two extreme positions of rotation of the first arm 203.1 around the central axis 210. The first arm 203.1 can thus travel a range of rotation angles between the two extreme positions defined by the left front stop 500.1. The range of rotation angles can be close to 180°.

[0106] The right front stop 500.2 is capable of limiting the rotation of the right part of the first crankshaft 120.1 comprising the second arm 203.2 and the second lateral element 202.2. For this purpose, the right front stop 500.2 can be arranged to come into abutment on the second arm 203.2 between two extreme positions of rotation of the second arm 203.2 around the central axis 210. The second arm 203.2 can thus travel a range of rotation angles between the two extreme positions defined by the right front stop 500.2. The range of rotation angles can be close to 180°.

[0107] The left front stop 500.1 and the right front stop 500.2 are capable of constraining the rotation of the first and second arms 203.1 and 203.2 around the central axis of the crankshaft, so that the central element 210 is lower than the axes of rotation of the right and left roads, when the foot support 110 is parallel to the mean contact plane 150.

[0108] Alternatively, a single stop may be provided to limit the rotation of the first crankshaft 120.1.

[0109] One or two similar stops may be provided to limit the rotation of the second crankshaft 120.2 located at the rear of the roller skate 100.

[0110] Thus, no restriction is attached to the number of stops of the roller skate according to this embodiment: the roller skate 100 can in particular comprise between one and four stops.

[0111] As shown in [Fig.5a], the stops may be integral with the foot support 120. Alternatively, the stops and the foot support 120 are one and the same piece, which facilitates the assembly of the roller skate 100.

[0112] Such stops advantageously ensure that the central element 201 is lower than the wheel rotation axes 211.1 and 211.2, and that consequently the foot support 120 is always in the balanced position. The crankshaft is thus always positioned in a “V” shape and not in the shape of a circumflex accent.

[0113] [Fig.5b] illustrates a side view in the same plane perpendicular to the central axis 210 than in [Fig.2a]. The stop 500.1 thus defines a range of rotation angles 510 of the first arm 203.1 around the central axis 203.1, and constrains the first arm 203.1 within this range.

[0114] As can be seen in [Fig.5b], the stop 500.1 is arranged in such a way that the lateral element associated with the left front wheel, the axis of rotation 211.1 of which is located under the central axis 210 of the front crankshaft, is always in the same half-space delimited by a plane normal to the direction of slippage and containing the central axis 210 of the crankshaft. In the case of the stop 500.1, this is the front half-space (on the left in [Fig.5b]), i.e. the half-space in front of the central axis 210 in the direction of slippage 170.

[0115] The right front stop 500.2 is arranged in such a way that the lateral element associated with the right front wheel, the axis of rotation 211.2 of which is located under the central axis 210 of the front crankshaft, is always in the other half-space delimited by the plane normal to the direction of skating and containing the central axis 210 of the crankshaft. Thus, this is the rear half-space, i.e. the half-space behind the central axis in the direction of skating 170.

[0116] The present invention is not limited to the embodiments described above as examples; it extends to other variants.

Claims

Claims

1. A roller skate (100) comprising a foot support (110), two front wheels (140.1; 141.1) and two rear wheels (140.2; 141.2), a first crankshaft (120.1) providing a connection between the two front wheels and the foot support and a second crankshaft (120.2) providing a connection between the two rear wheels and the foot support, wherein each of the first and second crankshafts comprises a central element (201) defining a central axis (210), a first lateral element (202.1) defining a first axis of rotation (211.1) of a left wheel and a second lateral element (202.2) defining a second axis of rotation (211.2) of a right wheel, a first arm connecting the central element to the first lateral element and a second arm connecting the central element to the second lateral element; for each of the first and second crankshafts, the first arm and the second arm forming an angle (220) around the central axis, said angle being strictly less than 180°, and greater than or equal to 90°, characterized in that, a direction of slip defining a vertical plane normal to said direction of slip, points of contact of the four wheels on the ground defining a mean plane of contact, for at least one of the first and second crankshafts (120.1; 120.2), the projection of the first axis of wheel rotation (211.1) in the vertical plane and / or the projection of the second axis of wheel rotation (211.2) in the vertical plane, is inclined by a camber angle (610.1; 610.2) with respect to the projection of the central axis of the crankshaft in said vertical plane of the roller skate, when respective intersections of wheel planes with the mean contact plane are parallel to each other and to the skating direction.

2. Roller skate according to claim 1, wherein, for each of the first and second crankshafts (120.1; 120.2), the angle (220) is between 130° and 170°, preferably between 130° and 160°, in particular between 140° and 150°.

3. Roller skate according to one of claims 1 to 2, wherein, for each of the first and second crankshafts (120.1; 120.2), the first and second crankshafts have a size (400) greater than a width (401) of the foot support (110), so that the wheels are positioned on either side of the foot support.

4. Roller skate according to one of the preceding claims, wherein, for at least one of the first and second crankshafts (120.1; 120.2), the central element (201) is capable of varying the angle (220) between the first arm (203.1) and the second arm (203.2).

5. Roller skate according to claim 4, in which the central element (201): - is made of a torsionally flexible material, for example spring steel; and / or - comprises a central zone of smaller section than right and left lateral zones of the central element.

6. Roller skate according to claim 4, wherein the central element (201): - comprises a right part (301.2), a left part (301.1) and a central part (300), the central part being capable of allowing rotation of the left part relative to the right part.

7. Roller skate according to one of claims 4 to 6, further comprising a return spring (302) placed between one of the first and second crankshafts (120.1; 120.2) and the support (110) and capable of exerting a return torque between the crankshaft and the support.

8. Roller skate according to one of the preceding claims, wherein, for at least one of the first and second crankshafts (120.1; 120.2), the first and second arms (203.1; 203.2) are made of a magnesium and aluminum alloy or a composite material of carbon fiber and polymer resin.

9. Roller skate according to one of the preceding claims, comprising at least two stops (500.1; 500.2) capable of constraining the rotation of at least one of the first and second crankshafts (120.1; 120.2) around the central axis (210) of said crankshaft, so that each lateral element associated with a wheel whose axis of rotation is located under the central axis of the crankshaft is always in the same half-space delimited by a plane normal to the skating direction and containing the central axis of the crankshaft.

10. Roller skate according to one of the preceding claims, wherein, for at least one of the first and second crankshafts (120.1; 120.2), the first arm (203.1) and the second arm (203.2) have different longitudinal sizes, the arm directed forward in a skating direction of the roller skate being shorter than the arm directed backward in the skating direction.

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