FR2618189A1 - Rotary actuator with modular blade - Google Patents

Abstract

Rotary actuator with blade able to withstand large axial loads and having integral distribution. It comprises on the body 3 of the actuator an entry E for the pressure line connected to an outlet D for the pressure line and an outlet S for the return line connected to an inlet A for the return line. The outlet D for the pressure line and the inlet A for the return line are fitted into the shaft 15 of the actuator and means of connection 25, 26 allow it to be fixed to a second identical actuator in such a way that the second actuator is fed with fluid from the first actuator.

Description

 The invention relates to a rotary actuator and in particular a rotary vane actuator.

 Pallet rotary actuators generally consist of a shaft comprising one or two pallets and one or two fixed partitions. The chambers thus created are alternately pressurized so as to apply a torque to the output shaft. The admissible axial loads are generally very reduced due to the absence of particular stops apart from the stop resulting from the shape of the shaft.

In addition, the association of two rotary vane cylinders in series, for example for the realization of a motorized articulation for a rotary arm in several parts poses multiple problems.
- mechanically, the result of external forces applied to the second cylinder induces axial loads - on the first, which causes operating difficulties
- in general, nothing is provided to mechanically connect the jacks to each other and the mounting surface of one of the jacks does not necessarily find its complement on the other jack
- the supply of fluid to the first cylinder does not usually pose difficulties, but it is not the same for the second cylinder which is movable relative to the frame. This complication of hydraulic distribution is accentuated with the number of associated cylinders
- Maintaining an angular position under load is not ensured in the absence of pressure, internal leakage generally inevitable, tables in this type of material require to provide a brake "lack of pressure".

 Although some of these problems are partially solved by existing equipment, the current cylinders still allow only to collect little axial force and do not have a practical hydraulic distribution system in case of association of several cylinders.

 The present invention therefore aims to achieve a rotary actuator capable of supporting large axial loads and having an integrated distribution allowing a simple and easy association to implement several actuators.

 The subject of the invention is a rotary actuator comprising a pressure line inlet and a return line outlet arranged on the body of the jack and which communicate with at least one chamber of the jack via a servovalve, characterized in that the inlet of the pressure line is also connected to a pressure line start through a pressure line associated with the cylinder body, a rotary pressure connection and a pressure passage arranged in the cylinder shaft, in that the return line outlet is connected to a return line inlet through a return pipe associated with the cylinder body, a rotary return connection and a passage for return arranged in the shaft of the jack, and in that it comprises connecting means making it possible to fix it on a second identical jack so as to allow the supply of fluid to the pressure line inlet of the second jack by the start of the pressure line of the first cylinder e t 1 evacuation of the fluid from the return line outlet of the second cylinder by the return line arrival of the first cylinder.

According to other characteristics
the cylinder body has at least one flat lateral face in which the pressure line inlet and the return line outlet are arranged, the pressure line start and the return line arrival being arranged in a complementary manner at a flat end of the cylinder shaft;
- pressure and return lines are formed in the cylinder body
- the return and pressure lines each respectively comprise a first axial portion and a second transverse portion which open into a circular groove of a cylindrical bore of the cylinder body. One of the ends of the pressure passage or the passage of return arranged in the shaft opens transversely to the axis of the latter opposite said groove to respectively constitute the rotary return or pressure connection
- The cylinder comprises means for taking up external radial and axial forces arranged in the vicinity of the end of the shaft where the start of the pressure line and the arrival of the return line are arranged.
the - the connecting means are constituted by a fixing flange mounted at the end of the shaft where the start of the pressure line and the arrival of the return line are arranged, and which is intended to be fixed on the face lateral plane of a second cylinder in which a pressure line inlet and a retouch line outlet are arranged;
blocking means in angular position placed at the end of the shaft opposite to that where the start of the pressure line and the arrival of the return line are provided, in order to block the jack in the angular position in 1 absence of pressure.

The invention will be described in more detail below with reference to the accompanying drawings, given only by way of example and in which
- Fig.1 shows a perspective view of a rotary actuator according to the invention
- Fig.2 shows a longitudinal sectional view of a set of two cylinders according to the invention associated in series
- Fig.3 shows a sectional view along line 3-3 of Fig.2; and
- Fig.4 shows an articulated robot arm whose motorized joints consist of a set of cylinders according to the invention.

 FIGS. 1 and 3 show a rotary vane jack according to the invention. In order to simplify the description, we have considered the case of a pallet jack comprising a movable pallet and a fixed partition, but it is understood that this example is not limiting and that the invention can be carried out with a rotary actuator comprising several pallets and fixed partitions.

 In Fig.2, there is shown a sectional view of a set of two identical cylinders 1, 2, placed perpendicularly to each other so as to explain the operation of the invention, but we do not will describe only one cylinder for the purpose of simplifying the disclosure.

 The rotary actuator 1 comprises a hollow body 3 of generally parallelepipedal shape internally provided with a fixed partition A. A shaft 5 carrying a movable pallet 6 (FIG. 3) is mounted rotating in the bore of the actuator and is arranged with respect to the latter in the axial direction. Conventionally, the supply of fluid to the chamber of the jack 1 is controlled by a servovalve 7 placed on the body 3. The body 3 of the jack has a flat face 9 on which are arranged an inlet E of pressure line and a return line outlet S communicating with the cylinder chamber via the servovalve 7 and intended for the distribution of the control fluid. Fixing holes 10 are arranged on the face 9 so as to allow connection with another cylinder as will be explained later in the description.

 The actuator body 3 has at each of its ends a cover 11, 13. Each cover comprises a flange 15, 17 and a cylindrical body 19, 21 through which the shaft 5 projects. Each cover is fixed to the actuator body 3 by known means, such as for example screws 22. At one 23 of the ends of the shaft 5 open a start D of the pressure line and an arrival A of the return line, arranged in a complementary manner to the arrangement of the pressure line input E and the return line output S on the face 9, that is to say that the distance between A and D is equal to that existing between E and S. The end 23 of the shaft has a flat face 24.

 A fixing flange 25 is mounted on the end 23 of the shaft 5 and is designed to be fixed on the flat face 9 of the body of a jack 2 identical to the jack 1. The fixing flange 25 has holes for fastening 26 arranged in a complementary manner to the holes 10 in the planar face 9 of the jack 1, that is to say on the face 9 of the jack 2.

 At the opposite end 27 of the shaft 5 and beyond the cover 13 is arranged a blocking system in angular position of general reference 28 whose role will be described in the following description.

 The pressure line input E intended for supplying pressurized fluid, for example oil, to the jack 1 is located on the flat face 9 of the jack body 3 and connected on the one hand to a pipe 29 d supply of the servovalve 7 (FIG. 3), and on the other hand to a pressure line 31 formed in the cylinder body 3. The pressure line 31 has a first axial portion 31a, parallel to the longitudinal axis of the cylinder body and a second transverse portion 31b disposed in the cover 13 of the cylinder body. The transverse portion 31b of the pressure line 31 extends perpendicular to the axial portion 31a and opens into a circular groove 33 of a cylindrical bore of the cover 13.One end 35 of a pressure passage 37 arranged in the shaft 5, parallel to the axis XX 'of the latter, opens eA opposite the circular groove 33 to constitute with the transverse portion 31b of the pressure line a rotating hydraulic connection 39. The other end of the passage of pressure 37 constitutes the start D of the pressure line and leads to the flat face 24 of the end 23 of the shaft 5.

 Similarly, the return line outlet S is connected on the one hand to the servovalve 7 and on the other hand to a return pipe 41 formed in the cylinder body 3. The return pipe 41 has a first axial portion 41a parallel to the axis of the cylinder body and a second transverse portion 41b disposed in the cover 11 of the cylinder body.

The transverse portion 41b of the return pipe 41 extends perpendicular to the first axial portion 41a and opens into a circular groove 43 of a cylindrical bore of the cover 11. One end 45 of a return passage 47 arranged in the shaft 5 parallel to the axis XX 'of the latter and disposed on the side of the axis XX' opposite the pressure passage 37, opens opposite the circular groove 43 to form with the transverse po-rtion 41b a return hydraulic connection 49 from the return pipe. The other end of the return passage 47 constitutes the return line inlet A and opens at the flat face 24 of the end 23 of the shaft 5.

 The shaft 5 is provided at each of its ends 23, 27 with means for taking up the axial and radial external forces. These means being symmetrical on the two ends, we will therefore only describe the means in relation to the cover 11. They consist of a stop 51 mounted on the shaft 5 and coming into contact with the cover 11 in the body of cover 19. The stop 51 is then hooped on the shaft 5 by removable biconical elements 53. The clearance between the cover 11 and the stop 51 is adjustable, and a needle stop 55 is placed between the flange 15 of the cover 11 and the stop 51 and contributes to the resumption of the axial forces. The radial forces are taken up by a needle bearing 57 placed between the stop 51 and the cover body 19. The elements 53 also serve as means for positioning and locking in axial position of the fixing flange 25.

 A blocking device in angular position, of general reference 28, is arranged at the end 27 of 1 shaft 5 and is intended to maintain the angular position of the jack in the absence of pressure. It comprises a conventional multiple disc brake system 60, integral in rotation with the body 3 of the jack. The brake system 60 comprises a braking bell 61 integral in rotation with the shaft 5 and a set of discs 63 is fixed to the body 21 of the cover 13 by means of screws 64. The brake system is actuated by a jack annular 65 comprising a piston 66 and a cylinder 67 and supplied by a line 68 connected in derivation of the transverse part 31b of the pressure line 31. The annular cylinder is mounted on the cylindrical body 21 of the cover 13 and acts on the system of brake via a disc 69. In the absence of pressure, the piston 60 is permanently biased by a stack of several elastic washers 7I disposed between the cylinder 67 of the annular jack and the flange 17 of the cover 13, in the direction corresponding to the tightening.

 The operating mode of the angular position locking device is as follows.

 During normal operation of the rotary actuator, the braking system is "released". Indeed, the pressurization of the annular jack moves it in the direction of the flange 17 of the cover 13, thus separating it from the disc 69 and causing it to compress the stack of elastic washers 71. The thrust of the annular jack on the brake system n 'is therefore more assured and the shaft 5 of the cylinder 1 can rotate freely. In the absence of pressure, the annular cylinder 65 is subjected to the stress of the elastic washers 71 and therefore comes into contact with the disc 69, act, thereby activating the brake system 60 and thus putting the blocking in position of the shaft 5 of cylinder 1.

 The actuator comprises, when used in closed loop, a position encoder not shown measuring the angle existing between the actuator body 3 and the actuator shaft 5. This angle measurement can also be carried out using the using an external potentiometer.

The jack according to the invention makes it possible to associate several identical jacks along orthogonal axes in a relatively simple manner, having minimized the complications presented by the fluid distribution system. Each cylinder has a pressure line and a return line, the pressure line comprising an inlet E and a flow
D and the return line comprising an outlet S and an inlet A. The assembly of several jacks is carried out in the following manner. We connect the end of the shaft 5 of a first jack in which the outlet D of pressure line and the return line inlet A and on which the fixing flange 25 is mounted, to the flat face 9 ′ of a second cylinder into which the pressure line inlet E and the outlet S of line-back from this second cylinder.

The fixing is carried out by screws passing through the respective complementary holes 26, 10 and it is then possible to supply from the first cylinder a succession of cylinders mounted perpendicular to each other, the supply lines for the pressurized fluid communicating the with each other, as do the return lines. There is therefore a system of several associated cylinders which can be easily supplied from a single source of fluid, which considerably simplifies the installation thereof and reduces the short thereof. Each cylinder is controlled by its own servovalve independently of the others, thus allowing a parallel distribution to be obtained on the n cylinders. The servovalve of each cylinder supplies one or the other chamber of the cylinder and thus allows two directions of rotation of 1 cylinder shaft,
The rotary actuator described above is used in a motorized articulation along two orthogonal axes for a robot arm in two parts, the articulation comprising a cylinder per axis and the cylinders being arranged so that the first part of the robot arm is connected to the body of a first cylinder and the second part of the robot arm is fixedly connected in rotation to the shaft of the second cylinder. FIG. 4 shows such a robot arm. The robot arm, of general reference 80 comprises two parts 81, 83 connected together by a hinge 85 constituted by a set of two identical jacks 1, 2 arranged perpendicular to one another. The robot arm 80 is connected to a frame 87 by a hinge 85a and ends with a tool, in the case shown here, a clamp 89, which is connected to it by a hinge 85b, the hinges 85a and 85b being identical to the articulation 85. The movement of the robot arm 80 is conventionally controlled by a control system (not shown) connected to the servovalves of the various cylinders of the articulations.

Claims (16)

 1. Rotary actuator comprising an inlet (E) of pressure line and an outlet (S) of return line arranged on the body (3) of the actuator which communicate with at least one chamber of the actuator via a servovalve (7), characterized in that the pressure line input <E) is also connected to a pressure line start (D) through a pressure line (31) associated with the body (3) of the jack , a rotary pressure connection (39) and a pressure passage (37) arranged in the cylinder shaft, in that the return line outlet (S) is connected to an inlet (A) of return line through a return pipe (41) associated with the body (3) of the jack, a rotary return connection (49) and a return passage (41) arranged in the shaft of the jack , and in that it comprises connecting means (25, 26) making it possible to fix said cylinder on a second identical cylinder (2) so as to allow the supply of fluid to the inlet (E) of pressure line d u second cylinder via said start (D) of the pressure line of the first cylinder and the evacuation of the fluid from the outlet (S) of return line of the second cylinder by said arrival (A) of return line of the first cylinder,  2. rotary actuator according to claim 1, characterized in that the body (13) of the actuator comprises at least one flat lateral face (9) in which are arranged the inlet (E) pressure line and the outlet (S) of return line and in that the start (D) of pressure line and the arrival (A) of return line are arranged in a complementary manner to a planar end (23) of the shaft (5) of the jack.  3. Cylinder according to claims 1 to 2, characterized in that the pressure line (31) is formed in the body (3) of the cylinder.  4. Cylinder according to claim 3, characterized in that said pressure line (31) comprises a first axial portion (31a) and a second transverse portion (31b) which opens into a circular groove (33) of a cylindrical bore of the body (3) of the cylinder and in that one of the ends of said pressure passage (37) arranged in the shaft (5) opens transversely to the axis of the latter opposite said groove, for constitute said rotary pressure connection (39).  5. Cylinder according to claims 1 to 2, characterized in that the return line 141) is formed in the body of the cylinder.  6. Cylinder according to claim 5, characterized in that said return pipe (41) comprises a first axial portion (41a) and a second transverse portion (41b) which opens into a circular groove (43) of a cylindrical bore of the body (3) of the actuator and in that one of the ends (45) of said return passage (47) arranged in the shaft (5) opens transversely to the axis of the latter, opposite said groove to form said rotating connection (49) back.  7. Cylinder according to claims 1 to 2, characterized in that it comprises means for taking up the radial and axial external forces arranged in the vicinity of the end (23) of the shaft (5) where the start is arranged ( D) line. pressure and the return line arrival (A).  8. Cylinder according to claim 7, characterized in that it also comprises means for taking up external radial and axial forces at the other end (27) of the shaft (5).  9. Cylinder according to claim 7, characterized in that the means for taking up the axial external forces consist of a stop (51) and by a bearing placed in the axial direction between a cover (11, 13) of the body (3) of the jack and said stop (51).  10. Cylinder according to claim 9, characterized in that the means for taking up the radial external forces comprise a bearing (57) for taking up the radial force placed in the radial direction between said cover (11,13) of the body (3) cylinder and said stop (51).  11. Cylinder according to any one of claims 2 to 8, characterized in that the connecting means (25) consist of a fixing flange (25) mounted on the end (23) of the shaft (5) of the cylinder where the start (D) of pressure line and the arrival (A) of return line are arranged and designed to be fixed on the flat lateral face (9 ') of said second cylinder.  12. Cylinder according to claim 11 characterized in that the fixing flange (25) comprises means (53) for positioning and locking in an axial position on the end (23) of the shaft (5).  13. Cylinder according to claim 1, characterized in that it comprises means (28) for locking in angular position placed at the end (27) of the shaft opposite to that where the start (D) of the line is arranged. pressure and the return line inlet (A), allowing the cylinder to be locked in position in the absence of pressure  14. Cylinder according to claim 13, characterized in that the locking means in angular position consist of a disc brake system (60) and elastic actuating means (71).  15. Cylinder according to claim 14, characterized in that the locking means in angular position comprise a release cylinder (65).  16. Motorized articulation along two orthogonal axes for robot arm in several parts (80), characterized in that it comprises -two actuators according to any one of the preceding claims arranged so that a part (81) of the arm robot is connected to the body of a first cylinder t1) and that another part (83) is fixedly connected in rotation to the shaft of the second cylinder (2).