Automatic locking device for mechanical arm

Abstract

The invention relates to a locking device (27) comprising a crown member (29) equipped with a bore (43), a bushing (31) rotatably movable with respect to the crown member, a plate body (55) integral with the bushing (31), a rocker (33) rotatably movable between a locking position and a release position, a groove (35) leading into the bore (43) and formed in the rocker or the plate body, a guide ramp (37), the rocker mechanism comprises a plate body (1) provided with a drilling hole and a guide slope (2) formed at the periphery of the rocker or the plate body, a bolt (39) installed in the groove to be clamped between the drilling hole and the guide slope when the rocker is in a locking position, and a return spring (41) acting between the plate body and the rocker to bring the rocker back to a release position.

Description

[0001] The present invention relates to a locking device for a mechanical arm and to a mechanical arm comprising such a locking device.

[0002] Articulated industrial mechanical arms are subject to gravity and depending on their configuration, a sudden stop of the power supply of the shaft motor can cause an uncontrolled movement of the arm before the motor brake effectively engages. This problem affects in particular mechanical arms comprising a vertical linear axis, because gravity has an impact whatever the configuration.

[0003] KR20120107270A describes a locking device for a vertical axis of a mechanical arm. The vertical movement of the arm is ensured using a screw rotated by a motor via a belt. The screw is integral with a gear.

[0004] A lever articulated on a frame has a drum pressing a belt by the action of a spring. In the event of a belt breakage, the spring causes the rotation of the lever and the teeth of the lever catch the gear.

[0005] This solution is only suitable for the breakage of a transmission belt and is ineffective in the event of a sudden power failure of the motor. In addition, this solution does not allow the locking of the screw by limiting its rotation.

[0006] The object of the present invention is to propose a locking device limiting the movement due to the weight of a mechanical arm in the event of a motor power outage.

[0007] To this end, the present invention relates to an automatic locking device for a first member and a second member of a mechanical arm, the first member and the second member being movable relative to each other, the locking device comprising:

[0008] - a crown member equipped with a borehole centered on a motor shaft fixed relative to the crown member and configured to be integral with the first member,

[0009] - a shaft sleeve configured to rotate around the motor shaft relative to the crown member using a motor belonging to the mechanical arm,

[0010] - a plate body rotating integral with the shaft sleeve around the motor shaft,

[0011] - a rocker carried by the plate body and rotatably movable relative to the plate body around a rocker shaft parallel to the motor shaft and non-coaxial to the motor shaft between a locking position and a release position,

[0012] - a groove formed in a first element among the rocker and the plate body, the groove following a groove axis extending radially relative to the motor shaft towards the borehole,

[0013] - a guide ramp formed at the periphery of a second element among the rocker and the plate body, the second element being different from the first element,

[0014] - a pin which is cylindrical and extends along a pin axis parallel to the motor axis, the pin being mounted in the recess to be translatable along the recess axis with respect to the first element when the rocker is in the release position and to be blocked between the bore and the guide ramp when the rocker is in the locked position, and

[0015] - a return spring acting between the plate and the rocker to exert a return force to bring the rocker back to the release position.

[0016] In the event of power cut to the motor, the rotation of the plate with respect to the crown member is blocked due to the movement of the pin and its blocking between the bore and the guide ramp. This causes the movement of the second member with respect to the first member to be blocked. The return spring ensures the triggering threshold of the locking device and ensures that the rotation of the plate with respect to the crown member can be automatically unlocked upon restoration of the power supply to the motor. Furthermore, since the locking device is integrated in the hub horizontally, whatever mechanical transmission is chosen, the motor can be used to drive the movement of the second member with respect to the first member and the locking device can function.

[0017] According to other advantageous aspects of the application, considered alone or in any technically possible combination, the locking device comprises one or more of the following features:

[0018] - when the direction of rotation of the hub is anticlockwise or clockwise respectively about the motor axis with respect to the crown member to drive the second member against gravity, the guide ramp is flat and the rocker moves from the release position to the locked position by rotating about the rocker axis with respect to the plate in the clockwise or anticlockwise direction respectively,

[0019] - the motor axis is arranged between the rocker axis and the recess,

[0020] - the guide ramp lies in a ramp plane which is parallel to the motor axis and which is inclined at an angle of 86 to 90 degrees, preferably 87 to 89 degrees and more preferably 88 degrees, with respect to a radial plane containing the motor axis and the rocker axis,

[0021] - the pin is free to rotate about the pin axis when the rocker is in the release position and the rotation of the pin about the pin axis is blocked by the insertion of the pin between the bore and the guide ramp when the rocker is in the locked position,

[0022] - when the rocker is in the release position, the centre of inertia of the rocker is positioned in a radial plane containing the rocker axis and the motor axis,

[0023] - when the rocker is in the release position, the centre of inertia of the assembly formed by the plate, the rocker, the return spring and the pin is positioned on the motor axis,

[0024] - the first element is a rocker and the second element is a plate,

[0025] - the first element is a plate and the second element is a rocker,

[0026] - when the rocker is in the release position, the return force exerted by the return spring tends to bring the pin against the stop wall of the second element,

[0027] - the guiding ramp is a first guiding ramp; a second guiding ramp, symmetrical to the first guiding ramp with respect to a radial plane containing the rocker axis and the motor axis, is formed on the second element, and when the rocker is in the release position, the return force exerted by the return spring tends to bring the pin so that the pin axis is in the radial plane,

[0028] - the locking device comprises: an additional rocker, carried by the plate and rotatably mobile with respect to the plate between a locking position and a release position, about an additional rocker axis parallel to the motor axis and non-coaxial to the motor axis; an additional recess, formed in a third element among the additional rocker and the plate, the additional recess extending radially with respect to the motor axis along an additional recess axis; an additional guiding ramp, formed at the periphery of a fourth element among the additional rocker and the plate, the fourth element being different from the third element; an additional cylindrical pin, extending along an additional pin axis parallel to the motor axis, the additional pin being mounted in the additional recess so as to be translatable with respect to the third element along the additional recess axis when the additional rocker is in the release position, so as to be blocked between the bore and the additional guiding ramp when the additional rocker is in the locking position; and an additional return spring, acting between the plate and the additional rocker to exert a return force bringing the additional rocker back to the release position.

[0029] The application also relates to a robotic arm comprising a first member, a second member movable with respect to the first member, and a locking device as described above, wherein the first member is driven by the hub, and the second member is integral with the crown, or the first member is integral with the crown, and the second member is driven by the hub.

[0030] According to other advantageous aspects of the application, the robotic arm comprises the following features:

[0031] - the second member is translatable with respect to the first member along a vertical axis,

[0032] - the robotic arm comprises a pinion integral in rotation with the hub about the motor axis, and a rack fixed to the second member, the rack being engaged with the pinion so that a rotation of the pinion about the motor axis causes a translation of the rack along the vertical axis with respect to the pinion.

[0033] The application will become more clearly understood by reading the following description, given only by way of non-limiting example, and made with reference to the accompanying drawings, in which:

[0034] Figure 1 is a front view of a robot arm integrally provided with a locking device according to a first embodiment of the present application,

[0035] Figure 2 is a detailed view of Figure 1 containing a partial section along a vertical plane passing through the motor shaft,

[0036] Figure 3 is a detailed view of a partial section of Figure 2 ,

[0037] Figure 4 is a front view of the locking device with the rocker in the release position,

[0038] Figure 5 is a view similar to that of Figure 4 with the rocker in the locking position,

[0039] Figure 6 is a view similar to that of Figure 3 showing a locking device according to a second embodiment of the present application,

[0040] Figure 7 is a view similar to that of Figure 6 showing the locking device in the release position, Figure 4

[0041] Figure 8 is a view similar to that of Figure 6 showing the locking device in the locking position, Figure 5

[0042] Figure 9 is a view similar to that of Figure 4 showing a locking device according to a third embodiment of the present application,

[0043] Figure 10 is a cross-sectional view along the plane X-X of Figure 9 ,

[0044] Figure 11 is a cross-sectional view along the plane XI-XI of Figure 9 ,

[0045] Figure 12 is a view similar to that of Figure 9 with the rocker in the locking position and the additional rocker in the release position,

[0046] Figure 13 is a view similar to that of Figure 9 with the rocker in the release position and the additional rocker in the locking position, and ​​

[0047] Figure 14 is a view similar to the view of Figure 5 illustrating a locking device according to a fourth embodiment of the application.

[0048] A robotic arm 1 according to a first embodiment of the application is described in Figure 1 The robotic arm 1 comprises a base 3, a column 5, an arm 7, a forearm 9, a flange 11, and a tool 13.

[0049] The base 3 is a first member of the robotic arm 1 and is fixed with respect to a horizontal plane P1 on which the base 3 rests. The horizontal plane P1 can be for example a floor, a workbench, or a table surface.

[0050] The column 5 is a second member of the robotic arm 1. When assembled on the robotic arm 1, the column 5 extends longitudinally along a vertical axis V perpendicular to the horizontal plane P1. Advantageously, the column 5 is translationally movable with respect to the base 3 along the vertical axis V.

[0051] The arm 7 extends parallel to the horizontal plane P1 when assembled on the robotic arm 1. The arm 7 is assembled at a first end 7a on the column 5 and is rotationally movable with respect to the column 5 about the vertical axis V.

[0052] The forearm 9 extends parallel to the horizontal plane P1 when assembled on the robotic arm 1. The forearm 9 is assembled at a first end 9a on a second end 7b of the arm 7 and is rotationally movable with respect to the arm 7 about a first rotation axis R1 parallel to the vertical axis V.

[0053] The flange 11 extends along an axis parallel to the vertical axis V when assembled on the robotic arm 1. The flange 11 is assembled at a first end 11a on a second end 9b of the forearm 9 and is rotationally movable with respect to the forearm 9 about a second rotation axis R2 parallel to the vertical axis V.

[0054] The tool 13 is assembled at a second end 11b of the flange 11. The tool is for example a gripper able to grasp a part.

[0055] The robotic arm 1 further comprises a movement system 15 to move the column 5 with respect to the base 3. The movement system 15 comprises an electric motor 17 and a mechanical transmission system 19.

[0056] The electric motor 17 extends along a motor axis A17 and comprises a stator 21 fixed to the base 3 and a motor shaft 23 rotating with respect to the stator 21 about the motor axis A17. The motor shaft 23 is thus rotating with respect to the base 3 about the motor axis A17.

[0057] Advantageously, the mechanical transmission system 19 comprises a pinion 25 and a rack 26.

[0058] The pinion 25 rotates integrally with the motor shaft rod 23 about the motor shaft A 17. The pinion 25 has teeth 36.

[0059] The rack 26 is fixed to the column 5 and has teeth, not shown, which can be engaged by the teeth 36 of the pinion 25 so that the rotation of the pinion 25 about the motor shaft A 17 causes a vertical translation of the column 5 via the rack 26 with respect to the base 3.

[0060] The robotic arm 1 also comprises an automatic locking device 27 of the robotic arm 1 described in Figures 2 to 5

[0061] The locking device 27 comprises a crown member 29, a bushing 31, a rocker 33, a recess 35, a guide ramp 37, a latch 39, and a return spring 41.

[0062] When the crown member 29 is mounted on the robotic arm 1, the crown member 29 is equipped with a bore 43 which is centered on the crown member 29 and which passes through the crown member 29 from one side to the other along the motor shaft A 17.

[0063] The bore 43 has a first inner portion 45 having a first inner diameter D1, a second inner portion 47 having a second inner diameter D2 which is smaller than the first inner diameter D1, and a third inner portion 49 having a third inner diameter D3 which is smaller than the second inner diameter D2. The reduction in diameter between the first inner diameter D1 and the second inner diameter D2 forms a first shoulder 51 belonging to the bore 43, and the reduction in diameter between the second inner diameter D2 and the third inner diameter D3 forms a second shoulder 53 belonging to the bore 43.

[0064] When the crown member 29 is mounted on the robotic arm 1, the crown member 29 is centered on the motor shaft A 17 and is fixed on the stator 21, the first inner portion 45 being turned toward the stator 21. The crown member 29 is thus integral with the base 3.

[0065] The bushing 31 is cylindrical and has an outer diameter D4 which is smaller than the third inner diameter D3.

[0066] The bushing 31 comprises a plate body 55. The plate body 55 extends perpendicularly to the axis of revolution of the bushing 31, which is coaxial with the motor shaft A 17 when the bushing 31 is mounted on the robotic arm 1. The plate body 55 is a revolving piece about the motor shaft A 17 when the bushing 31 is mounted on the robotic arm 1 and defines a second outer diameter D5 which is greater than the first outer diameter D4 and smaller than the first inner diameter D1.

[0067] ​Advantageously, the pinion 25 is integral with the bushing 31. More precisely, the pinion 25 and the bushing 31 are formed by a single integral piece. Alternatively, the pinion 25 can be a separate piece fixed by screws.

[0068] The end 32 of the bushing 31 is mounted on the motor shaft stem 23 and rotates integrally with the motor shaft stem 23 around the motor shaft A17. When the bushing 31 is mounted on the motor shaft stem 23, the bushing 31 is partially contained in the bore 43. More precisely, the plate body 55 is contained in the first inner portion 45 of the bore 43 and the pinion 25 protrudes outside the bore 43.

[0069] The locking system 27 comprises a ball bearing 57 which is inserted between the second inner portion 47 and the bushing 31 and abuts against the second shoulder 53. Thus, the bushing 31 is configured to rotate around the motor shaft A17 with respect to the crown member 29.

[0070] As can be seen in Figure 4 and 5 , in projection in a plane perpendicular to the motor shaft A17, the rocker 33 has an ovoid shape. The rocker 33 comprises a circular base 59, a circular portion 61, a first leg 63, and a second leg 65. The first leg 63 and the second leg 65 connect the circular base 59 to the circular portion 61, defining a recess 67 between the circular portion 61, the circular base 59, the first leg 63 and the second leg 65.

[0071] The circular portion 61 has a radius r1 which is smaller than the first diameter D1 divided by two.

[0072] At the junction with the circular portion 61, the first leg 63 comprises a protrusion 68 which extends into the recess 67.

[0073] The rocker 33 is carried by the bushing 31 and rotates integrally with the bushing 31 around the motor shaft A17.

[0074] More precisely, the rocker is mounted on the plate body 55 via a rocker shaft stem 69 which extends along a rocker shaft A33 which is parallel to the motor shaft A17 and non-coaxial with the motor shaft A17. The rocker shaft stem 69 is fixed to the plate body 55 and the circular base 59 is mounted in rotatable movement on the rocker shaft stem 69. The rocker is thus in rotatable movement around the rocker shaft A33 with respect to the bushing 31 between a release position and a locking position.

[0075] The rocker 33 is positioned along the motor shaft A17 between the stator 21 and the plate body 55 and the end 32 of the bushing 31 passes through the recess 67.

[0076] Advantageously, the center of inertia of the rocker 33 is positioned in a radial plane P2 containing the rocker axis A33 and the motor axis A17 when the rocker 33 is in the release position. Thus, the rocker 33 is not sensitive to centrifugal forces acting on the rocker 33 when the rocker 33 rotates around the motor axis A17. The center of inertia of the rocker is located on the side of the motor axis A17 with respect to the rocker axis A33.

[0077] The return spring 41 is fixed at a first end 41a to the plate body 55 and at a second end 41b to the protrusion 68. The return spring 41 acts on the plate body 55 and on the rocker 33 to exert a return force F tending to bring the rocker 33 back from the locked position to the release position.

[0078] The recess 35 is formed in a first element among the rocker 33 and the plate body 55. In this example, the recess 35 is advantageously formed in the rocker 33, which thus constitutes the first element. The recess 35 follows a recess axis A35 extending radially with respect to the motor axis A17 towards the bore 43. The recess 35 opens radially into the bore 43. In this example, the recess 35 passes through the plate body 55 parallel to the motor axis A17.

[0079] Advantageously, the motor axis A17 is arranged between the rocker axis A33 and the recess 35. This design allows a compact locking system 27.

[0080] The guide ramp 37 is flat and is formed at the periphery of a second element among the rocker 33 and the plate body 55, the second element being different from the first element. In this example, the guide ramp 37 is advantageously formed at the periphery of the plate body 55. The plate body 55 thus constitutes the second element. The guide ramp 37 passes through the radial plane P2 and extends perpendicularly to the rocker axis A33 up to the bore 43.

[0081] The guide ramp 37 is perpendicular to the radius of the plate body 55. More precisely, the guide ramp 37 is located within a ramp plane P3. The ramp plane P3 is parallel to the motor axis A17 and, advantageously, is inclined with respect to the radial plane P2 at an angle a between 86 and 90 degrees, preferably 87 to 90 degrees and more preferably 88 degrees.

[0082] The plate body advantageously comprises a stop wall 71 extending the guide ramp 37. The stop wall 71 is parallel to the radial plane P2.

[0083] The pin 39 is cylindrical and extends along a pin axis A39 which is parallel to the motor axis A17 when the pin is mounted on the mechanical arm 1. The pin is mounted in the recess 35 to be translatable with respect to the rocker 33 along a recess axis A35 when the rocker 33 is in the release position, and is blocked between the bore 43 and the guide ramp 37 when the rocker 33 is in the locking position. When the rocker 33 is in the release position, the recess axis A35 is perpendicular to the rocker axis A33 and is comprised in a radial plane P2. The recess 35 guides the pin 39 between the release position and the locking position of the rocker 33.

[0084] When the mechanical arm 1 is in the normal operating phase, that is to say when the motor shaft 23 rotates in the clockwise direction about the motor axis A17 with respect to the crown member 29, the rocker 33 is in the release position and the pin 39 is free to move along the recess 35 between the guide ramp 37 and the bore 43. The bushing 31, the rocker 33 and the pin 39 are then rotated about the motor axis A17 with respect to the crown member 29.

[0085] Advantageously, when the rocker 33 is in the release position, the pin 39 is also free to rotate about the pin axis A39 so as not to hinder the rotation of the bushing 31 and of the rocker 33 when the mechanical arm 1 is in the normal operating phase and the pin 39 contacts the bore 43.

[0086] Advantageously, when the locking device 27 is not activated, that is to say when the rocker 33 is in the release position, the return force F tends to bring the pin 39 against the stop wall 71.

[0087] When the locking device 27 is not activated, the pin axis A39, the motor axis A17 and the rocker axis A33 are in the radial plane P2, and advantageously the centre of inertia of the assembly formed by the bushing 31, the rocker 33, the return spring 41 and the pin 39 is positioned on the motor axis A17. This design of the locking device 27 ensures dynamic balance in the normal operating phase of the mechanical arm 1, in other words it guarantees that the centrifugal forces acting on the rocker 33 do not trigger the locking of the locking device 27.

[0088] During the deactivation of the motor 17, the effect of gravity causes the column 5 to fall, and the motor shaft 23 undergoes a strong acceleration A23 in the anticlockwise direction, as Figure 5As shown in the middle, due to its inertia, the rocker 33 then rotates around the rocker axis A33 relative to the plate body 55 from the release position to the locking position, advantageously in the clockwise direction, causing the pin 39 to move along the groove axis A35, along the groove 35 and along the guide ramp 37 until it comes into contact with the bore 43 of the crown member 29. When the rocker 33 is in the locking position, the plate body 55 and the bore 43 clamp the pin 39, which is inserted between the bore 43 and the guide ramp 37, and the rotation of the pin 39 around the pin axis A39 is advantageously blocked. Thus, the pin 39 directly blocks the plate body 55 relative to the crown member 29, and the motor shaft 23 can no longer rotate. The fall of the column 5 of the robotic arm 1 is then stopped.

[0089] When the rocker 33 moves from the release position to the locking position, the rolling of the pin 39 on the guide ramp 37 causes the friction forces exerted on the pin 39 to be limited and more stable, which would add to the return force F of the return spring 41, which is not conducive to the movement of the rocker 33 from the release position to the locking position.

[0090] The inclination of the guide ramp 37 when the locking device 27 is activated prevents the pin 39 from rebounding on the bore 43 from the locking position to the release position. The inclination of the guide ramp 37 also ensures the permanent wedging of the pin 39 between the bore 43 and the plate body 55.

[0091] The return force F of the return spring 41 is chosen based on the value of the angular acceleration expected to trigger the locking device 27. Thus, there is an acceleration threshold for the rocker 33 to start moving to the locking position. This allows the motor shaft 23 to rotate in the counterclockwise direction up to a defined acceleration threshold and ensures that the plate body 55 and the rocker 33 will never be blocked in the clockwise direction.

[0092] It is sufficient to activate the motor 17 in the clockwise direction to unlock the locking device 27.

[0093] In a non-representative variant, the mechanical transmission system 19 comprises a pinion 25 that rotates integrally with the motor shaft 23 and a belt fixed to the column 5 and driven by the pinion 25, so that the rotation of the pinion 25 around the motor axis A17 causes the vertical translation of the column 5 relative to the base 3 via the belt.

[0094] In a non-representative variant, the mechanical transmission system 19 comprises a pinion 25 that rotates integrally with the motor shaft 23 and a worm fixed to the column 5 and meshed by the pinion 25, so that the rotation of the pinion 25 around the motor axis A17 causes the vertical translation of the column 5 relative to the base 3 via the worm.

[0095] More generally, the application applies to a motor that translates a column 5 relative to a base 3.

[0096] In a non-representative variant, in normal operation the motor shaft 23 rotates in the counterclockwise direction with respect to the crown member 29. When the motor shaft 23 undergoes an imposed acceleration in the clockwise direction, the rocker 33 moves from the release position to the locking position by rotating in the clockwise direction with respect to the rocker axis A33.

[0097] In Figures 6 to 8 the locking device 127 according to a second embodiment is shown. When the referenced elements are the same, the reference numerals of the locking device 127 correspond to the reference numerals of the locking device 27. When the elements designated by these reference numerals are modified in the locking device 127 with respect to the locking device 27, their values are increased by 100 with respect to the reference numerals of the corresponding elements of the locking device 27.

[0098] If in a figure of Figures 6 to 8 the reference to an element is made without mentioning it in the description, it corresponds to the element having the same reference numeral in the first embodiment.

[0099] The locking device 127 is identical to the locking device 27 of the first embodiment, except for the features described below.

[0100] A recess 135 is formed in the plate body 155 and a guide ramp 137 and a stop wall 171 are formed at the periphery of the circular portion 161 of the rocker 133. The recess 135 follows a recess axis in the plane P2 that extends radially with respect to the motor axis A17 towards the bore 43. The operation of the locking device 127 when the rocker 133 moves from the release position to the locking position is similar to that of the locking device 27, the pin 39 being wedged between the bore 43 and the guide ramp 137.

[0101] In Figures 9 to 13 the locking device 227 according to a third embodiment is shown. When the referenced elements are the same, the reference numerals of the locking device 227 correspond to the reference numerals of the locking device 27. When the elements designated by these reference numerals are modified in the locking device 227 with respect to the locking device 27, their values are increased by 200 with respect to the reference numerals of the corresponding elements of the locking device 27.

[0102] If in a figure of Figures 9 to 13 the reference to an element is made without mentioning it in the description, it corresponds to the element having the same reference numeral in the first embodiment.

[0103] The locking device 227 is identical to the locking device 27 of the first embodiment, except for the features described below.

[0104] The locking device 227 comprises an additional rocker 273 similar to the rocker 33, carried by the plate body 255 and rotatably mobile with respect to the plate body 255 between a locking position and a release position about an additional rocker axis A273 parallel to the motor axis A17 and non-coaxial to the motor axis A17. The angle formed by the rocker axis A33, the motor axis A17 and the additional rocker axis A273 is equal to 90 degrees. The additional rocker 273 moves from the release position to the locking position in the opposite direction to the rocker 33, so that when the rocker 33 is in the locking position, the additional rocker 273 is in the release position; when the rocker 33 is in the release position, the additional rocker 273 is in the locking position. Alternatively, the angle formed by the rocker axis A33, the motor axis A17 and the additional rocker axis A273 can be different from 90 degrees and, for example, equal to 180 degrees.

[0105] The locking device 227 comprises an additional recess 275 formed in a third element among the additional rocker 273 and the plate body 255. In this example, the additional recess 275 is formed on the additional rocker 273. The additional recess 275 extends radially with respect to the motor axis A17 towards the bore 43 and opens into the bore 43, following an additional recess axis A275.

[0106] The locking device 227 comprises an additional guide ramp 277 formed at the periphery of a fourth element among the additional rocker 273 and the plate body 255, different from the third element. In this example, the additional guide ramp 277 is formed at the periphery of the plate body 255.

[0107] The locking device 227 comprises an additional cylindrical peg 279 extending along an additional peg axis A279 parallel to the motor axis A17, the additional peg 279 being mounted in the additional recess 275 to be translatable with respect to the additional rocker 273 along the additional recess axis A275 when the additional rocker 273 is in the release position and to be blocked between the bore 43 and the additional guide ramp 277 when the additional rocker 273 is in the locking position.

[0108] The locking device 227 comprises an additional return spring 281 acting between the plate body 255 and the additional rocker 273 to exert a return force F2 to bring the additional rocker 273 back to the release position.

[0109] The guide ramp 37 and the additional guide ramp 277 are opposite, so that when the motor shaft 23 undergoes a strong acceleration in one direction of rotation about the motor shaft A17, the additional rocker 273 moves to the locking position and the additional peg 279 catches the rotation between the plate body 255 and the crown member 29, and when the motor shaft 23 undergoes a strong acceleration in the other direction of rotation about the motor shaft A17, the rocker 33 moves to the locking position and the peg 39 catches the rotation between the plate body 255 and the crown member 29. Thus, whatever the direction of rotation, once the motor shaft 23 is subjected to a strong acceleration, the locking system 227 catches the rotation of the plate body 255 relative to the crown member 29. The locking device 227 thus allows catching of the second member 5 relative to the first member 3 in both directions of rotation of the hub 31 when the angular acceleration of the hub 31 exceeds a threshold value that can be adjusted by the choice of the return spring 41 and the additional return spring 281.

[0110] In Figure 14 A locking device 327 according to a fourth embodiment is shown in

[0111] If an element is cited in Figure 14 without being mentioned in the description, it corresponds to the element having the same reference in the first embodiment.

[0112] The locking device 327 is identical to the locking device 27 of the first embodiment, except for the features described below.

[0113] The plate body 355 comprises a second guide ramp 383 that is symmetrical to the first guide ramp 37 relative to the radial plane P2.

[0114] The second guide ramp 327 is perpendicular to the radius of the plate body 355. More precisely, the guide ramp 383 lies in a ramp plane P3'. The ramp plane P3' is parallel to the motor shaft A17 and, advantageously, is inclined relative to the radial plane P2 at an angle a' of between 86 and 90 degrees, preferably 87 to 90 degrees and more preferably 88 degrees.

[0115] When the rocker 333 is in the release position, the return force F exerted by the return spring 341 tends to bring the peg 39 so that the peg shaft A39 is in the radial plane P2. The peg 39 then occupies a position of equilibrium between the guide ramp 37 and the second guide ramp 383.

[0116] It should be understood that the locking device 327 does not comprise a stop wall extending the first ramp 35. Thus, whatever the direction of rotation of the motor shaft 23, the rocker 333 can tilt in any direction of rotation in order to wedge the peg 39 between the plate body 355 and the bore 43 to block the rotation of the motor shaft 23 when the motor shaft 23 is subjected to a strong acceleration.

[0117] Whatever the direction of rotation of the rocker 333 relative to the plate body 355, the return spring 341 acts between the rocker 333 and the plate body 355 in order to be able to return the rocker 333 to the release position.

[0118] In the described embodiment of the application, the stator 21 is integral with the base 3 and the rack 26 is integral with the column 5, the application is fully applicable to a robotic arm in which the stator is integral with the column and the rack is fixed relative to the base.

[0119] Similarly, in the described embodiment of the application, the motor shaft is the rotor of the motor, the application is fully applicable if the motor shaft is the output shaft of a reducer coupled to the motor.

[0120] Furthermore, the application is applicable to a robotic arm in which the first member is a rotatable movement relative to the second member. By way of example, it can be implemented on a joint of a forearm on an arm of a 6-axis industrial robot.

[0121] Any feature described above in relation to one embodiment or variant is applicable, where technically possible, to other described embodiments and variants.

Claims

1. An automatic locking device (27; 127; 227; 327) for a first member (3) and a second member (5) of a robot arm (1), said first member (3) and second member (5) being movable relative to each other, said locking device (27; 127; 227; 327) comprising: - a crown (29) equipped with a bore (43) centered on a motor shaft (A17) fixed relative to said crown member (29) and configured to be integral with said first member (3), - a bushing (31) configured to be rotated about said motor shaft (A17) relative to said crown member (29) using a motor (17) belonging to said robot arm (1), - a plate body (55; 155; 255; 355) integral in rotation with said bushing (31) about said motor shaft (A17), - a rocker (33; 133; 333) carried by said plate body (55; 155; 255; 355) and rotatable relative to said plate body (55; 155; 255; 355) about a rocker shaft (A33; A133) parallel to said motor shaft (A17) and non-coaxial with said motor shaft (A17) between a locking position and a release position, - a recess (35; 135) formed in a first element among said rocker (33; 133; 333) and said plate body (55; 155; 255; 355), said recess (35; 135) following a recess axis (A35) extending radially relative to said motor shaft (A17) towards said bore (43), - a guide ramp (37; 137) formed at a periphery of a second element among said rocker (33; 133; 333) and said plate body (55; 155; 255; 355), said second element being different from said first element, - a latch (39) which is cylindrical and extends along a latch axis (A39) parallel to said motor shaft (A17), said latch (39) being mounted in said recess (35; 135) to be translatable relative to said first element along said recess axis (A35) when said rocker (33; 133; 333) is in the release position and to be caught between said bore (43) and said guide ramp (37; 137) when said rocker (33; 133; 333) is in the locking position, and - a return spring (41; 341) acting between said plate body (55; 155; 255; 355) and said rocker (33; 133; 333) to exert a return force (F) to bring said rocker (33; 133; 333) back to the release position.

2. The locking device (27; 127; 227; 327) according to claim 1, characterized in that When the direction of rotation of the bushing (31) is anticlockwise, clockwise respectively with respect to the crown member (29) about the motor shaft (A17) to drive the second member (5) against gravity, the guide ramp (37; 137) is flat and the rocker (33; 133; 333) moves from the release position to the locked position by rotating about the rocker shaft (A33; A133) in the clockwise direction, anticlockwise direction respectively with respect to the plate body (55; 155; 255; 355).

3. The locking device (27; 127; 227; 327) according to any one of claims 1 or 2, characterized in that, The motor shaft (A17) is arranged between the rocker shaft (A33; A133) and the recess (35; 135).

4. The locking device (27; 127; 227; 327) according to any one of claims 1 or 2, characterized in that, The guide ramp (37; 137) lies in a ramp plane (P3) which is parallel to the motor shaft (A17) and which is inclined at an angle (a) of 86 to 90 degrees with respect to a radial plane (P2) containing the motor shaft (A17) and the rocker shaft (A33; A133).

5. The locking device (27; 127; 227; 327) according to claim 4, characterized in that The angle (a) is equal to 87 to 89 degrees.

6. The locking device (27; 127; 227; 327) according to claim 5, characterized in that The angle (a) is equal to 88 degrees.

7. The locking device (27; 127; 227; 327) according to any one of claims 1 or 2, characterized in that, - the bolt (39) is free to rotate about the bolt shaft (A39) when the rocker (33; 133; 333) is in the release position, and - the rotation of the bolt (39) about the bolt shaft (A39) is blocked by the insertion of the bolt (39) between the bore (43) and the guide ramp (37; 137) when the rocker (33; 133; 333) is in the locked position.

8. The locking device (27; 127; 227; 327) according to any one of claims 1 or 2, characterized in that, The centre of inertia of the rocker (33; 133; 333) is located in a radial plane (P2) containing the rocker shaft (A33; A133) and the motor shaft (A17) when the rocker (33; 133; 333) is in the release position.

9. The locking device (27; 127; 227; 327) according to any one of claims 1 or 2, characterized in that, The centre of inertia of the assembly formed by the plate body (55; 155; 255; 355), the rocker (33; 133; 333), the return spring (41; 341) and the bolt (39) is located on the motor shaft (A17) when the rocker (33; 133; 333) is in the release position.

10. The locking device (27; 227; 327) according to any one of claims 1 or 2, characterized in that, The first element is the rocker (33; 333) and the second element is the plate body (55; 255; 355).

11. The locking device (127) according to any one of claims 1 or 2, characterized in that The first element is the plate body (155) and the second element is the rocker (133).

12. The locking device (27; 127; 227) according to any one of claims 1 or 2, characterized in that, The return force (F) exerted by the return spring (41) tends to bring the bolt (39) against the stop wall (71; 171) of the second element when the rocker (33; 133) is in the release position.

13. The locking device (327) according to any one of claims 1 or 2, characterized in that: - the guide ramp (37) is a first guide ramp, - a second guide ramp (383) symmetrical to the first guide ramp (37) with respect to a radial plane (P2) containing the rocker shaft (A33) and the motor shaft (A17), formed on the second element (355), and - when the rocker (333) is in the release position, the return force (F) exerted by the return spring (41) tends to entrain the peg (39) so that the peg shaft (A39) is in the radial plane (P2).

14. The locking device (227) according to any one of claims 1 or 2, comprising: - an additional rocker (273) carried by the plate body (255) and rotatably movable with respect to the plate body (255) between a locking position and a release position about an additional rocker shaft (A273) parallel to the motor shaft (A17) and non-coaxial to the motor shaft (A17), - an additional recess (275) formed in a third element among the additional rocker (273) and the plate body (255), the additional recess (275) extending radially with respect to the motor shaft (A17) towards the bore (43) following an additional recess axis (A275), - an additional guide ramp (277) formed at a periphery of a fourth element among the additional rocker (273) and the plate body (255), the fourth element being different from the third element, - an additional cylindrical peg (279) extending along an additional peg shaft (A39279) parallel to the motor shaft (A17), the additional peg (279) being mounted in the additional recess (277) to be translatable with respect to the third element along the additional recess axis (A275) when the additional rocker (273) is in the release position, and to be blocked between the bore (43) and the additional guide ramp (A275) when the additional rocker (273) is in the locking position; and an additional return spring (281) acting between the plate body (255) and the additional rocker (273) to exert a return force (F2) to bring the additional rocker (273) back to the release position.

15. A robotic arm (1), comprising: - a first member (3), - a second member (5) movable with respect to the first member (3), and - a locking device (27; 127; 227; 327) according to any one of claims 1 or 2, characterized in that the first member (3) is driven by the bushing (31) and the second member (5) is integral with the crown member (29), or the first member (3) is integral with the crown member (29) and the second member (5) is driven by the bushing (31).

16. The robot arm (1) according to claim 15, characterized in that The second member (5) is translatable with respect to the first member (3) along a vertical axis (V).

17. - The robotic arm (1) according to claim 16, comprising a pinion (25) integral with the bushing (31) for rotation about the motor shaft (A17) and a rack (26) fixed to the second member (5), the rack (26) being meshed with the pinion (25) in such a way that the rotation of the pinion (25) about the motor shaft (A17) causes the translation of the rack (26) along the vertical axis (V) with respect to the pinion (25).

Images