System for determining rotation information of member

Abstract

To provide a determination system capable of securing reliability of a reading distance of a high-sensitivity pattern.SOLUTION: A system for determining rotational information of a member 1 about an axis R, comprises encoders 11 and 12 carried by a body 50 rotatably connected to the member 1 and having tracks 11a and 12a capable of emitting periodic signals representative of rotational displacement of the member 1, and a sensor disposed at a reading distance (d) from the tracks 11a and 12a and including sensitive patterns 15 and 16 providing information as a function of the displacement. The system comprises a casing 17 in which the member 1 is rotatably mounted by a bearing 18, and a module 19 fixed in the casing 17 and associated with the sensor, where a guide bearing 18 is carried by the module 19, and a spacer 26 for adjusting the reading distance (d) is disposed between the body 50 and the guide bearing 18.SELECTED DRAWING: Figure 5

Description

Detailed Description of the Invention

[0001] The present disclosure relates to a system for determining rotational information of a member about an axis by means of a device comprising an encoder and a sensor.

[0002] In particular, the encoder is carried by a body rotatably connected to the member, presenting a track capable of emitting a periodic signal representative of the rotational displacement of said member, and the sensor includes a sensitive pattern positioned at a reading distance from said track to provide rotational information as a function of said displacement.

[0003] Depending on the specific application, the system can be used to determine the torque applied between two rotating components, particularly components that are integrated in transmitting engine torque to a vehicle, such as the electric motor or pedal assembly of an electric assist bicycle and a mechanical transmission.

[0004] For this purpose, it is known to use a test body having an inner section rotatably connected to a member and an outer section extending around the inner section and having means for connecting said body to a second member, said sections being concentrically connected about an axis by a deformable structure arranged to transmit torque between said members while allowing angular displacement between said sections as a function of a torque applied between said members.

[0005] Such a test specimen can be fitted with two concentric encoders, each presenting a track, each presenting successive pairs of north and south poles to form a multi-pole magnetic track that provides a pseudo-sinusoidal magnetic signal.

[0006] The sensor consists of two sensitive patterns, each placed at a reading distance from the track, which compare the displacement of the sections to determine the applied torque.

[0007] Patent documents FR-2 816 051, FR-2 821 931 and FR-2 862 382 describe the comparison of such signals to determine the angular gap between the sections, whereby a torque is applied to induce said angle by twisting the deformable structure.

[0008] In known systems, there is a problem of setting the reading distance between the sensitive pattern and the corresponding encoder track, which must be done accurately.

[0009] In particular, when determining torque, the reading distances of both sensors must be stable and equal so as not to distort the determination.

[0010] The object of the present disclosure is to improve upon the prior art, in particular by proposing in a particularly simple way a determination system that makes it possible to ensure the reliability of the reading distance of a highly sensitive pattern.

[0011] To this end, the present disclosure proposes a system for determining information about the rotation of a member around an axis by means of a device, the device comprising: an encoder carried by a body rotatably connected to the member and having a track capable of producing a periodic signal representative of rotational displacement of the member; a sensor arranged at a reading distance from said track and comprising a sensitive pattern providing information as a function of said displacement; The system comprises a casing in which the member is rotatably mounted by a guide bearing, and a module fixed within the casing and associated with the sensor, the guide bearing being carried by the module, and a spacer being arranged between the bearing and a body carrying the encoder to adjust the reading distance. [Brief explanation of the drawings]

[0012] Further objects and advantages of the present disclosure will become apparent from the following description taken in conjunction with the accompanying drawings. [Figure 1] 1 is a partially exploded perspective view of a pedal assembly of an electrically assisted bicycle equipped with a system according to the present disclosure for determining a rotational torque between two members rotating about a rotation axis. [Figure 1a] 1 shows the assembly of the rolling bearings in the module. [Figure 2] 2A and 2B are perspective and axial cross-sectional views of the module shown in FIG. 1. [Figure 3] FIG. 10 is an exploded perspective view showing the assembly of the sensor in the module shown in the previous figure. [Figure 4] FIG. 10 is an exploded perspective view showing the mounting in the casing of the module, bearing, and sensor assembly shown in the previous figures. [Figure 5] 1 shows a partial axial cross section of a pedal assembly of an electrically assisted bicycle equipped with the determination system shown in the preceding figures. [Figure 5a] In a diagram similar to FIG. 5, a pedal assembly of an electrically assisted bicycle equipped with a determination system according to each modification of an embodiment of the present disclosure is shown. [Figure 5b] In a diagram similar to FIG. 5, a pedal assembly of an electrically assisted bicycle equipped with a determination system according to each modification of an embodiment of the present disclosure is shown. [Figure 5c] In a diagram similar to FIG. 5, a pedal assembly of an electrically assisted bicycle equipped with a determination system according to each modification of an embodiment of the present disclosure is shown.

[0013] In connection with these figures, a system for determining information relating to the rotation of member 1 about axis R will now be described.

[0014] Spatial positioning terms are used herein with reference to the axis of rotation R. In particular, the terms "inner" and "outer" refer to dispositions proximate to and away from this axis R, respectively, and the terms "axial" and "radial" refer to dispositions along this axis R and dispositions moving away from or toward this axis R, respectively. Furthermore, the terms "internal" and "external" refer to dispositions to one side and the other, respectively, along the R axis, and in particular refer to lower and upper in FIG. 5 .

[0015] According to a particular application, the system is capable of determining the torque applied between two members 1 rotating about an axis R, said members being integrated in the transmission of motor torque to a vehicle, for example the pedal assembly of an electric bicycle.

[0016] In other applications, the system may be used to determine different types of information, such as the position or rotational speed of a rotating member.

[0017] According to the embodiment shown, one of the members 1 comprises a part 2 for rotating the member 1. In particular, Figure 1 shows a pedal assembly for an electric bicycle comprising a crank 2 with pedals 3, said crank being attached to a shaft 1a that is driven in rotation about an axis R, forming a member 1 for applying a pedaling torque M+ in the pedaling direction.

[0018] The system comprises a test body 50 making it possible to transmit the pedaling torque M+ to a second member. In particular, the second member may comprise a sleeve arranged concentrically around the shaft 1a, said sleeve being connected, for example, to a satellite carrier of an epicyclic gear train of an electric gearbox, and which exerts a rotational torque directed in the opposite direction to the pedaling torque M+.

[0019] In this application, the pedaling force F at the tip of pedal 3 considered according to standard EN15194:2017 is 1,500 N, which, with a crank 2 length of 165 mm, generates a pedaling torque M+ of the order of 250 Nm. In particular, the torque transmitted by the test specimen is only in one direction of rotation (represented by the M+ arrow in the diagram), the other direction corresponding to the freewheel of the bicycle.

[0020] The test specimen 50 has an inner section 4 rotatably connected to the first member 1 and an outer section 5 extending around the inner section 4 and having means for connecting the test specimen to a second member.

[0021] With reference to the figure, the inner section 4 comprises a bore 6 provided with means for coupling to the shaft 1a, in particular in the form of splines 7a arranged to engage complementary ribs 7b formed in circumferential relief on the outer periphery of said shaft.

[0022] With regard to the connection with the second part, Figure 1 shows an outer section 5 whose inner peripheral wall has at least one radial lobe 8. This outer section is provided with means 9 for fixing said outer section to the sleeve of said second part, as previously mentioned. In particular, three lobes 8 are provided at 120°, each of which has a hole 9 for attachment, in particular by means of a pin or by screwing into a complementary hole in the sleeve.

[0023] The sections 4, 5 are concentrically connected about the axis R by a deformable structure arranged to transmit torque between the members while allowing angular displacement between said sections in response to torque applied between said members.

[0024] In particular, the torque resulting from the pedaling torque M+ on the inner section 4 and the torque applied by the second member on the outer section 5 cause a twist between the sections 4, 5 and therefore a relative angular displacement of said sections according to the twist angle which is a function of said torque.

[0025] In the illustrated embodiment, the deformable structure comprises a set of branches 10 arranged at an angle between the sections 4, 5. In particular, the branches 10 and the sections 4, 5 are integrally formed, in particular by stamping and / or cutting a void in a metallic material.

[0026] The branches 10 are angled relative to the direction of rotation, creating a lever arm that exerts a tensile stress on the branches 10, which is very effective in reducing stress and therefore increasing stiffness.

[0027] In Figure 1, the test specimen 50 consists of three branches 10, each of which has a curved shape designed to ensure an effective lever arm effect while taking up little radial space, with the lobes 8 each extending radially to the outer curve of the respective branch 10.

[0028] The system includes a device for determining the angle between sections 4, 5, this angle being a function of the applied torque, in particular by taking into account the stiffness of the deformable structure.

[0029] For this purpose, the device comprises two concentric encoders carried by the respective sections 4, 5 of the test body 50, comprising an inner encoder 11 and a respective outer encoder 12 rotatably connected to the inner section 4 and the respective outer section 5, each having a track 11a, 12a capable of emitting a signal representative of the rotational displacement of the respective member 1.

[0030] In other applications, the body 50 may be provided with one or more encoders 11, 12 to determine information about the rotation of the member 1, such as its position or rotational speed.

[0031] In the illustrated embodiment, each encoder 11, 12 is fixed to a respective section 4, 5 and carries an inner 11a and an outer 12a magnetic track, respectively, capable of emitting a periodic signal representative of the rotational displacement of the corresponding section 4, 5.

[0032] Each of the encoders 11, 12 is carried by an inner 11b and an outer 12b frame, respectively, the inner 4 -respectively outer 5- section having means for fastening the inner 11b -respectively outer 12b- frame thereto, in particular in the form of screwed or riveted orifices 4a, 5a.

[0033] Referring to Figure 1, inner section 4 has an outer peripheral wall provided with three radial lobes 13, and outer section 5 has three radial lobes 14 formed on its inner peripheral wall angularly offset from lobe 8 for attachment to a second member, each section 4, 5 being arranged at 120° to each other and having three attachment orifices 4a, 5a formed in each lobe 13, 14.

[0034] In one embodiment, consecutive north and south pole pairs magnetize each encoder 11, 12 to form a multi-pole magnetic track 11a, 12a capable of emitting a quasi-sinusoidal magnetic signal.

[0035] The encoders 11, 12 may each consist of an annular matrix, for example made of a plastic or elastomeric material, in which magnetic particles, in particular ferrite particles or rare earth particles such as NdFeB, are dispersed, said particles being magnetized to form magnetic tracks 11a, 12a.

[0036] The determination device also includes sensors each including at least two sensitive patterns on the inside 15 and the outside 16, positioned at a reading distance d from the tracks on the inside 11a and the outside 12a, respectively, and providing information about the rotation of the corresponding member 1 as a function of its displacement.

[0037] In the embodiment shown, each sensitive pattern 15, 16 is arranged to provide a signal representative of the angular position of the corresponding encoder 11, 12, which the sensor uses to compare the displacement of corresponding sections 4, 5 to determine the angular gap between said sections, which is a function of the applied torque.

[0038] According to one embodiment, each pattern 15, 16 comprises at least two sensitive elements, in particular a plurality of aligned sensitive elements, as described in documents FR-2 792 403, EP-2 602 593 and EP-2 602 594.

[0039] The sensitive element can be based on a magnetoresistive material, for example of the AMR, TMR, GMR type, or a Hall effect probe, whose resistance changes depending on the magnetic signal of the track 11a, 12a to be detected.

[0040] In one embodiment, the angular position can be determined incrementally by means of signals emitted by the magnetic tracks 11a, 12a. In particular, the sensitive patterns 15, 16 can be arranged to emit quadrature incremental square wave signals, the sensors comprising comparison means having counting means indicating the angular position of each of the encoders 11, 12 and subtraction means for calculating the difference between said angular positions, as described in particular in documents FR-2 816 051, FR-2 821 931 and FR-2 862 382.

[0041] In one embodiment, the angular position can be determined absolutely, i.e. relative to a reference position, by providing a secondary magnetic track or specific coding on the washer of the encoder 11, 12, so that the sensor pattern can be positioned at a reading distance d from said track or coding.

[0042] With reference to the figure, the determination system further comprises a casing 17 in which the member 1 is rotatably mounted by means of guide bearings 18, and a module 19 fixed to the casing 17 and associated with a sensor.

[0043] In particular, the casing 17 comprises an outer wall 20 provided with a bore 21 in which a rotating shaft 1a is rotatably mounted by means of bearings 18, said rotating shaft having an end 22 projecting from said outer wall with a crank 2 for applying a pedaling torque M+.

[0044] The casing 17 has a cavity 23 that forms a housing 24 in which the module 19 and the test specimen 50 are disposed. In the figure, the outer wall 20 of the casing 17 is surrounded by a skirt 25 that defines the housing 24, and the module 19 and the sensor are disposed within the housing, surrounded by the skirt in the circumferential direction, so that they are housed integrally within the casing.

[0045] Furthermore, the guide bearing 18 is carried by the module 19, and a spacer 26 for adjusting the reading distance d is placed between the test object 50 and said bearing.

[0046] This arrangement makes the reading distance d, and therefore the accuracy of the transmitted signal, more reliable, as it makes it possible to directly define the distance d by the positioning of the bearing 18 and sensitive patterns 15, 16 relative to the module 19, the positioning of the tracks 11a, 12a relative to the body 50, and the length of the spacer 26.

[0047] In the illustrated embodiment, the module 19 comprises a barrel 27 having an outer wall disposed within the bore 21 and an inner wall that carries the guide bearing 18 .

[0048] A sealing element 28 is attached to the outer wall of the barrel 27 at its interface with the bore 21 in order to prevent, on the one hand, leakage of lubricating oil into the housing 24 of the casing 17 and, on the other hand, to prevent the ingress of external contaminants such as water, dust and / or sludge into the housing.

[0049] In the illustrated embodiment, the system comprises an O-ring 28 disposed in an annular groove 29 formed for this purpose in the outer wall of the barrel 27 (Figs. 2, 5, 5a) and / or in the inner wall of the bore 21 (Figs. 5b, 5c) to seal the interface between the module 19 and said bore.

[0050] Similarly, the inner wall of barrel 27 is provided at its interface with member 1 with an annular sealing element 30 which rests axially on an annular flange 31 formed in the inner wall for this purpose.

[0051] In Figures 5 and 5a, the module 19 is formed by molding, in particular, a polymer material. In Figures 5b and 5c, the module 19 is formed by pressing a sheet of metal material, and the barrel 27 is formed by two axially oriented inner 27a and outer 27b walls joined by an outer fold 27c.

[0052] The guide bearing 18 comprises an inner ring 32 mounted around the member 1 and an outer ring 33 carried by the module 19, with rolling elements, in particular in the form of balls 34, arranged between said rings to guide their relative rotation.

[0053] In Figures 5, 5a and 5b, the outer ring 33 is associated with the wall of the module 19, in particular by means of a circlip-type washer 35a (Figures 5, 5a) or by means of an inner radial fold 35b (Figure 5b) formed by pressing the inner end of the inner wall 27a.

[0054] In Figure 5c, the module 19 has walls, in particular the inner wall 27a of its barrel 27, which itself forms the outer ring 33. Thus, the outer raceway of the ball 34 is pressed into the inner wall 27a, and the annular flange 31 is formed on the outside of said raceway.

[0055] The inner ring 32 is mounted around the shaft 1a and has an outer wall 32a axially supported on said shaft 1a. In particular, the crank 2 has an axial stop 2a which the outer wall 32a supports, possibly via a ring 36 arranged between said stop and said wall.

[0056] Advantageously, the ring 36 is attached to the shaft 1 a with an intervening sealing member, in particular in the form of an O-ring 37 .

[0057] The spacer 26 is supported axially against the inner wall 32b of the inner ring 32. In Figures 5, 5b and 5c, the spacer 26 is supported axially against the outer wall of the body 50, and also against the radial wall formed on the outside of the rib 7b that engages the shaft 1a with the body.

[0058] In Figure 5a, the spacer 26 is integrally formed with the body 50. To this end, the body has an axially extending nose 38 for forming said spacer. Alternatively, the inner ring 32 may have a similar nose for forming the spacer 26 and / or said spacer may include a shoulder formed around the shaft 1a.

[0059] With reference to the figure, the body 50 has an inner wall 39 a which is supported axially on the member 1 by means of a washer 39 .

[0060] In particular, washer 39 is a "circlip" type spring washer mounted in an annular groove 40 formed in the outer periphery of rotating shaft 1a and is positioned to apply an axial force pressing spacer 26 against guide bearing 18.

[0061] In the illustration, the module 19 also includes a radially extending plate 41 having an inner wall on which the sensors are mounted.

[0062] Advantageously, the plate 41 is screwed into a blind hole 42 in the casing 17. This arrangement ensures that the outer wall 20 of the casing 17 is free of protruding fastening elements, which avoids the risk of a collision with the crank 2, but also the risk of oil leakage and / or the ingress of external contaminants through orifices penetrating the outer wall. Furthermore, by fixing the sensor directly to the casing 17, it is precisely positioned with respect to the axis of rotation R, in particular with the planes of the sensitive patterns 15, 16 arranged perpendicular to the axis R.

[0063] In the illustration, the plate 41 has three equal angled holes 43 so that it can be fixed to the exterior wall 20 by suitable screws 44 .

[0064] The sensor is mounted on a printed circuit board 45, which is attached to the module 19. In particular, the board 45 is fixed to the inner wall of the plate 41 by two screws 46.

[0065] In the case of the module 19 formed by pressing a sheet of metal material (FIGS. 5b, 5c), the plate 41 is formed by axially stacking at least two walls connected by a fold, in order to ensure said plate a sufficient thickness to ensure its rigidity, in particular with regard to screwing into the casing 17 and / or screwing in the sensor board 45. Furthermore, in this embodiment, a sufficient threading length is ensured for the screws for fixing the electronic board 45 while remaining retracted from the encoders 11, 12.

Claims

1. A system for determining rotation information of a member (1) about an axis (R) by means of a device, comprising: The device comprises: an encoder (11, 12) carried by a body (50) rotatably connected to said member and having a track (11a, 12a) capable of emitting a periodic signal representative of the rotational displacement of said member; a sensor arranged at a reading distance (d) from said track (11a, 12a) and comprising a sensitive pattern (15, 16) providing information as a function of said displacement, The system comprises: a casing (17) in which said member is rotatably mounted by guide bearings (18); a module (19) fixed in said casing (17) and having said sensor associated therewith; The system is characterized in that the guide bearing (18) is carried by the module (19), and a spacer (26) is arranged between the body (50) and the guide bearing (18) to adjust the reading distance (d).

2. The casing (17) has a bore (21) in which the member (1) is rotatably mounted; 2. The system according to claim 1, wherein the module (19) comprises a barrel (27) having an outer wall arranged in the bore and an inner wall carrying a guide bearing (18).

3. The guide bearing (18) comprises an inner ring (32) mounted around the member (1) and an outer ring (33) carried by the module (19); 3. Determination system according to claim 1, characterized in that rolling elements (34) are arranged between the rings to guide their relative rotation.

4. 4. The determination system according to claim 3, characterized in that the outer ring (33) is associated with a wall of the module (19).

5. 4. The system according to claim 3, wherein said module (19) has a wall (27a) forming said outer ring (33).

6. 4. The determination system according to claim 3, wherein the spacer (26) is supported axially against the inner wall (32b) of the inner ring (32).

7. 4. The determination system according to claim 3, characterized in that the inner ring (32) has an outer wall (32a) axially supported on the member (1).

8. 2. The determination system according to claim 1, wherein the spacer (26) is supported axially against the outer wall of the body (50).

9. 2. The determination system of claim 1, wherein said body (50) has an axially extending nose (38) for forming said spacer (26).

10. 2. A determination system according to claim 1, characterized in that said body (50) has an inner wall (39a) supported in the axial direction of said member (1) by means of a washer (39).

11. The module (19) has a radially extending plate (41), The determination system according to claim 1 , wherein the plate has an inner wall on which the sensor is attached.

12. 12. The determination system according to claim 11, characterized in that the plate (41) is screwed into a blind hole (42) in the casing (17).

13. The sensor is mounted on a printed circuit board (45); 2. The determination system according to claim 1, characterized in that the substrate is attached to the module (19).

14. said body (50) carries two concentric encoders (11, 12) each having a track (11a, 12a); 2. The system according to claim 1, characterized in that the sensor comprises at least two sensitive patterns (15, 16) each positioned at a reading distance (d) from a track (11a, 12a).

15. The body (50) an inner section (4) rotatably connected to the member (1); an outer section (5) extending around the inner section (4) and having means (9) for connecting the body to a second member; the sections are concentrically connected about the axis (R) by a deformable structure (10) arranged to transmit torque between the members (1) while allowing angular displacement between the sections as a function of the torque applied between the members; The encoders (11, 12) are carried by sections (4, 5) respectively; 15. The determination system of claim 14, wherein the sensor compares the displacements of the sections to determine the applied torque.

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