Electric wheel and rolling vehicle equipped with such a wheel

Abstract

Electric wheel (3) comprising a hollow body (4) having a hub (5) defining an axis of rotation (XX') of the wheel, said hollow body (4) delimiting a cavity (6) inside which are housed an electric motor (7) with a rotor (8) capable of rotating about a motor shaft (YY') and a system (9) for transmitting the rotational movement of the rotor (8) to the body (4) to rotate the body (4) about the axis of rotation (XX') of the wheel (3), the motor shaft (YY') which does not intersect the axis of rotation (XX') extending in a plane perpendicular to the axis of rotation (XX') of the wheel (3) and the rotating body (4) comprising circular teeth fixed in rotation to said body (4), and center disposed on the axis of rotation (XX') of the wheel (3). The transmission system (9) comprises a worm gear (11) that can be rotationally locked to the rotor (8) and is adapted to mesh with the teeth (10). Figure for the abbreviated version: Fig. 1

Description

Title of the invention: Electric wheel and rolling machine equipped with such a wheel

[0001] The present invention relates to an electric wheel and a rolling machine equipped with such a wheel.

[0002] It relates in particular to an electric wheel comprising a hollow body having a hub suitable for mounting on a shaft and defining an axis of rotation of the wheel, said hollow body delimiting a cavity inside which are housed an electric motor with a rotor capable of rotating around a motor shaft and a system for transmitting the rotational movement of the rotor to the body to rotate the body around the axis of rotation of the wheel, the motor shaft which does not intersect the axis of rotation extending in a plane substantially perpendicular, that is to say perpendicular to within 10°, to the axis of rotation of the wheel and the rotating body comprising teeth fixed in rotation to said body, these teeth being circular teeth of a circle whose center is located on the axis of rotation of the wheel.

[0003] Motorized electric wheels that integrate a motor inside the wheel are known. Most electric wheels include a central motor coaxial with the wheel's axis of rotation. This results in a bulky and heavy wheel due to the motor's diameter and thickness. Other electric wheels incorporate a motor whose motor shaft is not parallel to the wheel's axis of rotation. The solutions adopted for transmitting the rotational motion from the rotor to the wheel body are complex and / or bulky and / or noisy and / or demanding in terms of positioning.

[0004] One object of the invention is to propose an electric wheel of the aforementioned type whose design allows a reduction in the size of said wheel without harming its performance and its simplicity of manufacture.

[0005] To this end, the invention relates to an electric wheel comprising a hollow body having a hub defining an axis of rotation of the wheel, said hollow body delimiting a cavity within which are housed an electric motor with a rotor capable of rotating about a drive shaft and a system for transmitting the rotational motion of the rotor to the body to rotate the body about the axis of rotation of the wheel, the drive shaft, which does not intersect the axis of rotation, extending in a plane substantially perpendicular to the axis of rotation of the wheel, and the rotating body comprising teeth fixed in rotation to said body, these teeth being circular teeth with a circle whose center is located on the axis of rotation of the wheel, characterized in that the transmission system comprises a worm gear able to be locked in rotation with the rotor and able to engage by meshing with the teeth.

[0006] The position of the motor shaft relative to the wheel's rotation axis and its combination with a motion transmission system incorporating a worm gear offer numerous advantages. Engaging a worm gear with circular teeth in the aforementioned motor position reduces the overall size due to the combination of a small motor with large-diameter circular teeth, thus achieving a high reduction ratio while allowing at least partial positioning of the motor within the teeth. The worm gear, in conjunction with the teeth, therefore offers the possibility of a high reduction ratio, a low-noise assembly, and a relatively large degree of spatial positioning freedom, which facilitates the mounting and operation of the wheel.

[0007] According to one embodiment of the invention, the worm gear and the drive shaft are coaxial. This results in a simpler design and assembly, as well as a reduced footprint.

[0008] According to one embodiment of the invention, the worm extends in a plane substantially perpendicular to the axis of rotation of the wheel. By substantially perpendicular, we mean perpendicular to within ±10°.

[0009] According to one embodiment of the invention, the teeth comprise so-called axial teeth which extend in projection from a plane perpendicular to the axis of rotation of the wheel.

[0010] According to one embodiment of the invention, the motor is arranged inside a virtual cylinder whose axis coincides with the axis of rotation of the wheel and whose diameter is equal to the largest diameter of the circular teeth. Preferably, the motor is arranged inside a virtual cylinder, that is to say, an imaginary or virtual cylinder, whose axis coincides with the axis of rotation of the wheel and whose diameter is equal to the smallest diameter of the circular teeth.

[0011] According to one embodiment of the invention, the teeth and at least part of the body are made from a single piece.

[0012] According to one embodiment of the invention, the wheel comprises a shaft, called the wheel shaft, around which the hub is mounted. This wheel shaft carries a motor support disposed inside the body cavity, the motor being coupled directly or indirectly to said motor support. The fact that the motor shaft does not intersect the axis of rotation of the wheel allows the use of a wheel shaft of simple shape that does not have to go around the motor, so that such a wheel shaft can be more rigid.

[0013] According to one embodiment of the invention, the motor support comprises a housing inside which the worm gear is mounted for free rotation, this worm gear being couplingable to the motor rotor, a part of the motor other than the rotor being positioned in contact with a part of the motor support, forming a stop to prevent rotation of said part of the motor. Again, this results in simpler implementation.

[0014] According to one embodiment of the invention, the body comprises, located inside the body cavity and rotationally fixed to the body, at least one circular track centered on the axis of rotation of the wheel and extending coaxially with the teeth. The motor support is equipped, for each track, with one or more guide elements, each guide element, such as a bearing or a pad, being capable of making rolling or sliding contact with said track. The presence of one or more guide elements ensures meshing even in the case of geometric defects in the components, which can be produced by molding. It should be noted that the torque transmitted by the motor generates forces in the teeth. These forces act in the direction of a separation between the teeth and the worm gear. The guide elements ensure meshing even under these conditions.

[0015] According to one embodiment of the invention, the motor support being for the or at least one of the tracks equipped with several guide elements, said guide elements extend on either side of a radial plane to the track passing through the gripping area by worm gear / tooth meshing.

[0016] According to one embodiment of the invention, the body comprises two facing walls forming the sides or rims of the wheel and a circumferential peripheral wall connecting said facing walls and forming the rim of the wheel. There are at least two circular tracks arranged opposite each other on the facing walls of said body. Preferably, the teeth are surrounded by one or at least one of the tracks. Thus, in the case of two facing tracks, the position of the tracks close to the rim allows control of the distance between the two tracks, since this distance is primarily determined by the thickness of the rim.

[0017] According to one embodiment of the invention, the motor support is mounted with play on said wheel shaft so as to be able to oscillate around an axis orthogonal to the axis of rotation of the wheel.

[0018] The invention also relates to a rolling machine characterized in that it is equipped with at least one electric wheel conforming to that described above.

[0019] Preferably, the rolling machine, which includes at least one electric wheel of the aforementioned type, is a mowing machine comprising at least one mowing element, such as a rotating cutting blade. Brief description of the drawings

[0020] The invention will be better understood upon reading the following description of exemplary embodiments, with reference to the accompanying drawings in which:

[0021] [Fig-1] represents a perspective view, in exploded position, of the elements constituting, of an electric wheel conforming to the invention;

[0022] [Fig.2] represents a perspective view of an electric wheel conforming to the invention in its assembled state;

[0023] [Fig.3] represents a schematic view of an electric wheel according to the invention to illustrate the concept of an imaginary or fictitious cylinder;

[0024] [Fig.4] represents a partial cross-sectional view of an electric wheel in accordance with the invention;

[0025] [Fig. 5] represents a partial cross-sectional view of an electric wheel in accordance with the invention;

[0026] [Fig. 6] represents a partial longitudinal cross-sectional view of an electric wheel in accordance with the invention;

[0027] [Fig.7] represents a partial view of an electric wheel according to the invention at the state of being electrically connected to a power supply;

[0028] [Fig.8] represents two schematic partial cross-sectional views of an electric wheel in accordance with the invention to illustrate the oscillation of the motor support;

[0029] [Fig.9] represents a perspective view of the motor support of the screw motor without end and wheel shaft in exploded view of said elements;

[0030] [Fig. 10] represents, in schematic form, different examples of guiding elements;

[0031] [Fig. 11] represents a partial cross-sectional view of an electric wheel according to the invention associated with two detail views;

[0032] [Fig. 12] represents a perspective view of a rolling machine equipped with an electric wheel according to the invention;

[0033] [Fig. 13] represents, in the form of two views, one in the assembled state, the other in the unassembled state, the immobilization in rotation of a part of the motor by stop with the motor support;

[0034] [Fig. 14] represents a partial perspective view of the inside of an electric wheel according to the invention;

[0035] [Fig. 15] represents a partial exploded view of part of the elements of [Fig. 14],

[0036] As mentioned above, the invention relates to an electric wheel 3 of the type shown in Figures 1 and 2. This electric wheel 3 is suitable for equipping a rolling machine 1, as illustrated in [Fig. 12]. This rolling machine 1 is here a mowing machine which comprises at least one mowing element 2 formed, for example, by a rotating blade and at least two electric drive wheels 3.

[0037] This mowing machine 1 can be an autonomous machine of the robot type, i.e., without a driver as illustrated, or a mowing machine with a driver walking behind the machine, such as a lawnmower, or a mowing machine with an onboard driver, such as a riding mower. Obviously, other applications of the electric wheel, which will be described later, can be considered without departing from the scope of the invention.

[0038] One or more of the electric wheels 3 suitable for equipping such a rolling machine is a drive wheel. This electric wheel 3 comprises a hollow body 4 having a hub 5 suitable for mounting on a shaft 14, called the wheel shaft. This hub 5 forms a circular recess. This hub 5 defines an axis XX' of rotation of the wheel 3. The hollow body 4 delimits a cavity 6 inside which are housed an electric motor 7 with a rotor 8 capable of rotating about a motor shaft YY' and a system 9 for transmitting the rotational motion of the rotor 8 to the body 4 to rotate the body 4 about the axis XX' of rotation of the wheel 3.

[0039] By "rotor of the electric motor 7", we mean here the rotating elements of said motor, these rotating elements including the motor shaft, when such a shaft is present.

[0040] The motor 7 further includes a stator which here groups together all the static elements of the motor 7.

[0041] To minimize the width, i.e., the thickness, of the electric drive wheel 3 without impairing its operation, the motor shaft YY' and the rotation axis XX' of the wheel 3 are non-coaxial and non-parallel. Furthermore, the motor shaft YY' and the rotation axis XX' of the wheel 3 do not intersect.

[0042] In practice, the motor shaft YY' extends in a plane P that is substantially perpendicular, that is, perpendicular to within ±10°, to the axis XX' of rotation of the electric wheel 3. The motor shaft YY' and the axis XX' of rotation of the wheel 3 are orthogonal to each other, as can be seen in [Fig. 3], which makes it possible to reduce the width of the electric wheel 3.

[0043] The motor 7 is an electric motor of the smallest possible dimensions. Ideally, the motor 7 has an overall diameter of less than 40 mm for a robot, 50 mm for a lawnmower, 70 mm for a snowplow, and 120 mm for a tractor. Such a motor 7 rotates at high speed. It is therefore essential that the system 9 for transmitting the rotational motion from the rotor 8 of the motor 7 to the body 4 of the wheel 3 incorporates a speed reducer. This speed reduction is achieved through the design of the gear that transmits the motion.

[0044] As can be seen in [Fig.4], the system 9 for transmitting the rotational movement of the rotor 8 to the body 4 comprises a driven element in the form of a toothed gear 10 fixed in rotation to the body 4 and a driving element, in the form of a worm gear 11 suitable for being driven in rotation by the motor 7.

[0045] This worm gear 11 can therefore be rotationally locked to the rotor 8 and is capable of engaging by meshing with the teeth 10. This worm gear 11 and the motor shaft YY' are coaxial. Thus, the worm gear directly engages with the rotor 8 of the motor 7. This connection is either permanent or made in a switchable / disconnectable manner. In the example shown, the rotor incorporates a motor shaft along the extension of which the worm gear is located.

[0046] This worm screw 11 extends in a plane P substantially perpendicular to the axis of rotation XX' of the wheel, that is to say perpendicular to within 10° of said axis of rotation XX' as illustrated in [Fig.6].

[0047] The tooth 10 is a circular tooth with a circle center disposed on the axis XX' of rotation of the wheel 3 and the worm screw 11 is able to engage by meshing with the tooth 10.

[0048] As shown in [Fig.6], the toothing 10 includes teeth 12, called axial teeth, which extend outward from a plane P2 perpendicular to the axis XX' of rotation of the wheel 3. Ideally, the toothing 10 and at least part of the body 4 are made in one piece, for example in synthetic material.

[0049] In the example shown in [Fig.7], the body 4 comprises two facing walls 19 forming the sides or rims of the wheel 3 and a circumferential peripheral wall 20 connecting said facing walls 19 to each other and forming the rim of the wheel 3. The circumferential peripheral wall may incorporate a tread or this tread may be attached.

[0050] In the example of [Fig. 11], the tread, shown as 200, is attached. A portion of this tread 200, which is made of elastic material, is sandwiched between a portion of the circumferential peripheral wall 20 and a portion of one of the walls 19 forming a flank of the wheel 3 in the coupled state of the peripheral wall 20 and the wall 19 forming a flank of the wheel 3. This sandwiching ensures the sealing of the cavity 6 delimited by the body 4 at this point. The coupling is achieved, in the example shown, by means of screws 27.

[0051] The facing walls and the circumferential wall can be made of a synthetic material, and the teeth are formed in one piece with one of the two facing walls 19. Thus, the teeth project from the face of said wall towards the facing wall. It is therefore understood that the rotation of the worm gear engaged with the motor rotor drives, by meshing of the worm gear with said teeth, the rotation of the wheel body.

[0052] To optimize the position of the motor 7, as illustrated in [Fig. 3], the motor 7 is arranged inside a fictitious, i.e., imaginary or virtual, cylinder 13, whose axis coincides with the axis XX' of rotation of the wheel 3 and whose diameter is equal to the largest diameter of the circular teeth 10. Ideally, the motor 7 is arranged inside a fictitious cylinder 13, that is to say imaginary or virtual, whose axis is coincident with the axis XX' of rotation of the wheel 3 and whose diameter is equal to the smallest diameter of the circular toothing 10.

[0053] To allow the wheel body 4 to rotate around the axis XX' of rotation of the wheel 3, the wheel 3 includes a shaft called the wheel shaft 14 around which the hub 5 is mounted. A seal, shown at 23 in [Fig. 11], ensures a seal between the wheel shaft 14 and the hub 5. The cavity delimited by the body is therefore, in the assembled state of the electric wheel 3, a closed cavity. The shaft 14 carries a motor support 15 disposed at least partially inside the cavity of the body 4. The hub 5 is formed by a simple circular opening inside at least one of the walls 19 facing the wheel body 4, into which a portion of the wheel shaft 14 is inserted. This wheel shaft 14 carries the motor support 15 to which the motor 7 is coupled directly or indirectly. The wheel shaft 14 / motor support 15 assembly forms a fixed rotating assembly around which the wheel body 4 rotates.An example of motor mount 15 is provided in [Fig.9].

[0054] As can be seen in [Fig. 8], the motor support 15 includes a through-hole so that it can be threaded onto the wheel shaft 14 to form a fixed assembly with it during movement. For this purpose, the housing may have grooves into which axial ribs of the wheel shaft 14 fit. This motor support 15 is preferably made of a synthetic material. Alternatively, this motor support 15 may be made of metal, in particular an aluminum alloy. This motor support 15 has a generally triangular shape, but its shape may vary. This motor support 15 is housed at least partially inside the cavity 6 of the body 4.

[0055] To allow rotation of the body 4 around the wheel shaft 14, bearing elements are provided. These bearing elements are visible in [Fig.8].

[0056] The motor support 15 includes a housing 16, visible in [Fig. 1], with an axis orthogonal to the axis of the through housing for receiving the wheel shaft 14. This housing 16 serves to receive the worm gear 11, which is mounted to rotate freely by means of at least one bearing 22 inside the housing 16. This bearing or these bearings 22 allow, in addition to the rotation of the worm gear 11 relative to the motor support 15, the coupling of the worm gear 11 to the motor support 15 by means of an external circumferential peripheral shoulder of the worm gear 11, visible in [Fig. 4]. The associated bearing 22 is axially immobilized in the housing 16 by means of a locking member, such as a clip 26, visible in particular in Figures 1 and 5. A part of the motor, other than the rotor 8 and shown in 71 in [Fig. 1], is also shown in Figures 22. 13], is positioned in contact against a part 151 of the motor support 15 forming a stop for immobilizing the rotation of said part of the motor.Thus, the part. not to rotate the motor is immobilized in rotation by simple contact of pressure on the motor support 15. The motor 7 extends in cantilever relative to the worm screw 11.

[0057] To allow meshing, even when the wheel body 3 is deformed, the body 4 comprises, located inside the cavity 6 of the body 4 and rotationally fixed to the body 4, at least one circular track 17 with center located on the axis XX' of rotation of the wheel 3, extending coaxially with the teeth 10. In practice, preferably, the track 17 surrounds the teeth 10. The track 17 is thus located as close as possible to the rim. The spacing between two opposing tracks is thus better controlled. The motor support 15 is equipped, for each track, with one or more guide elements 18. Each guide element 18, such as a bearing or a slide, is capable of making rolling or sliding contact with said track 17.

[0058] In the example of Figures 4 and 5, two guide members 18 are provided, each formed by a bearing. Each bearing is screw-coupled to the motor support 15. To ensure optimal guidance without having to multiply the guide members 18, the guide members 18 extend on either side of a plane PI radial to the track 17 and passing through the meshing area of ​​the worm gear 11 and the teeth 10.

[0059] Examples of guide members 18 are provided in [Fig. 10]. Each guide member 18 may be a rolling or sliding guide member and may or may not be rotary. Each guide member 18 may be made in one piece with another guide member, as illustrated in [Fig. 10]. The guide members may be mounted in a separate manner on a common support.

[0060] Each circular track 17 is arranged opposite another circular track. The circular tracks 17 are thus arranged opposite each other on the walls 19 opposite the body 4 for the confinement of the guide members 18 between said tracks.

[0061] As can be seen in [Fig. 8], the motor support 15 is mounted with clearance on the wheel shaft 14 so that it can oscillate about an axis orthogonal to the axis XX' of rotation of the wheel 3. This clearance is present at the through-hole of the motor support 15, allowing the motor support 15 to be threaded onto the wheel shaft 14. Thus, even in the event of deformation of the wheel 3, the guide members 18 can bear against the body of the wheel 3 at the level of the tracks 17. The guide members 18 therefore simultaneously ensure, by bearing contact with the tracks 17, guidance guaranteeing the possibility of coupling by meshing between the teeth 10 and the worm gear 11.

[0062] To supply electricity to the motor 7, an electrical wiring harness 21 is provided. This electrical wiring harness 21, visible in Figures 7 and 15, passes through the wheel shaft and the hub. This wiring harness 21 allows connection to the battery Power supply is provided when the motor's power supply battery is located outside the body 4. This electrical wiring 21 allows the power supply battery to be recharged when the wheel motor's power supply battery 210 is housed inside the cavity 6 of the body 4. Obviously, a single wheel can include one or more electric motors. The control of the motor(s) 7 is achieved using a control unit 25, visible in Figures 14 and 15. This control unit 25 is in the form of an electronic and computer system that includes, for example, a microprocessor and working memory. In a particular configuration, the control unit can be in the form of a programmable logic controller (PLC). In other words, the functions and steps described can be implemented as a computer program or via hardware components (e.g., programmable gate arrays).In particular, the functions and steps performed by the control unit or its modules can be carried out by instruction sets or computer modules implemented in a processor or controller, or by dedicated electronic components, or by components such as field-programmable gate arrays (FPGAs), or application-specific integrated circuits (ASICs). It is also possible to combine computer and electronic components.When it is specified that the unit or means or modules of said unit are configured to perform a given operation, this means that the unit includes computer instructions and the corresponding means of execution which enable said operation to be performed and / or that the unit includes corresponding electronic components.

[0063] The control unit 25 and the battery 210 are, when arranged inside the cavity 6 of the body 4, fixed to the motor support 15.

[0064] The operation of such a wheel is simple. The supply of electricity to the motor 7 causes a rotation of the rotor 8 which in turn drives the worm gear 11 which meshes with the teeth 10 which are fixed in rotation to the body 4 of the wheel 3. The guide members 18 ensure in parallel, by contact with the tracks 17, a guidance guaranteeing a possibility of coupling by meshing between the worm gear and the teeth.

Claims

Demands

1. Electric wheel (3) comprising a hollow body (4) having a hub (5) defining an axis of rotation (XX') of the wheel, said hollow body (4) delimiting a cavity (6) inside which are housed an electric motor (7) with a rotor (8) capable of rotating about a motor shaft (YY') and a system (9) for transmitting the rotational motion of the rotor (8) to the body (4) to rotate the body (4) about the axis of rotation (XX') of the wheel (3), the motor shaft (YY') which does not intersect the axis of rotation (XX') extending in a plane (P) substantially perpendicular to the axis of rotation (XX') of the wheel (3) and the rotating body (4) comprising teeth fixed in rotation to said body (4), these teeth (10) being circular teeth with a circle whose center is disposed on the axis of rotation (XX') of the wheel (3),characterized in that the transmission system (9) comprises a worm screw (11) that can be rotationally locked to the rotor (8) and is capable of engaging by meshing with the teeth (10).

2. Electric wheel (3) according to claim 1, characterized in that the worm gear (11) and the motor shaft (YY') are coaxial.

3. Electric wheel (3) according to any one of claims 1 or 2, characterized in that the worm gear (11) extends in a plane (P) substantially perpendicular to the axis of rotation (XX') of the wheel (3).

4. Electric wheel (3) according to any one of claims 1 to 3, characterized in that the teeth (10) comprise axial teeth (12) which extend in projection from a plane (P2) perpendicular to the axis of rotation (XX') of the wheel (3).

5. Electric wheel (3) according to any one of claims 1 to 4, characterized in that the motor (7) is arranged inside a fictitious cylinder whose axis coincides with the axis of rotation (XX') of the wheel (3) and whose diameter is equal to the largest diameter of the circular toothing (10).

6. Electric wheel (3) according to any one of claims 1 to 5, characterized in that the teeth (10) and at least a part of the body (4) are made of a single piece.

7. An electric wheel (3) according to any one of claims 1 to 6, characterized in that the wheel (3) comprises a shaft (14), called the wheel shaft, around which the hub (5) is mounted, this wheel shaft (14) carrying a motor support (15) disposed inside the cavity (6) of the body (4), the motor (7) being coupled directly or indirectly to said motor support (15).

8. Electric wheel (3) according to claim 7, characterized in that the motor support (15) comprises a housing (16) inside which the worm gear (11) is mounted freely to rotate, this worm gear (11) being couplingable to the rotor (8) of the motor (7), a part of the motor (7) other than the rotor (8) being positioned in contact with a part of the motor support (15) forming a stop for immobilizing the rotation of said part of the motor (7).

9. Electric wheel (3) according to any one of claims 7 or 8, characterized in that the body (4) comprises, disposed inside the cavity (6) of the body (4) and rotationally fixed to the body, at least one circular track (17) of circle center disposed on the axis of rotation (XX') of the wheel (3) to extend coaxially with the teeth (10), and in that the motor support (15) is equipped, by track (17), with one or more guide elements (18), each guide element (18), such as a bearing or a pad, being able to come into rolling or sliding contact with said track (17).

10. Electric wheel (3) according to claim 9, characterized in that the motor support (15) being for the or at least one of the tracks (17) equipped with several guide members (18), said guide members (18) extend on either side of a plane (PI) radial to the track (17) passing through the engagement zone by worm gear (11) / tooth (10).

11. Electric wheel (3) according to any one of claims 9 or 10, characterized in that the body (4) comprises two facing walls (19) forming the sides or sails of the wheel (3) and a circumferential peripheral wall (20) connecting said facing walls (19) to each other and forming the rim of the wheel (3) and in that the circular tracks (17) are at least two in number and are arranged facing each other on the facing walls (19) of said body (4).

12. Electric wheel (3) according to any one of claims 7 to 11, characterized in that the motor support (15) is mounted with clearance on said wheel shaft (14) so ​​as to be able to oscillate about an axis orthogonal to the axis of rotation (XX') of the wheel (3).

13. Rolling device (1) characterized in that it is equipped with at least one electric wheel (3) conforming to one of claims 1 to 12.

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