FR2641342A1 - FLUID ACTUATOR - Google Patents

Abstract

Actuating cylinder 1 comprising a cylinder 2, of which a piston 8 is movable longitudinally and which comprises between this piston and at least one radial end wall 6 of the cylinder a fluid chamber 9 and fluid flow means connected to this room. These flow means 15 comprise means 19 for limiting the flow of the fluid when the piston 8 moves, at least in one direction, over part of its stroke. Said flow means 15 further comprise means 30 for avoiding said limiting means 19 when the piston moves in its other direction.

Description

FLUID ACTUATOR

  The present invention relates to an actuating cylinder

  fluid, for example hydraulic or pneumatic.

  To vary the relative speed of the piston relative to the cylinder of the actuating cylinders, the pressure of the actuating fluid is varied. This way of proceeding requires the provision of fluid supply systems for the cylinders comprising control means adapted to be able to make these variations. The present invention proposes, on the contrary, an actuating cylinder which makes it possible to vary the speed of movement of its piston relative to its cylinder without auxiliary means.

control.

  The actuating cylinder of the invention comprises a cylinder of which a piston is longitudinally movable and comprises between this piston and at least one radial wall at the end of the cylinder a fluid chamber and means for draining the

fluid connected to this room.

  In accordance with the present invention, said flow means comprise means for limiting the flow of the fluid when the piston moves, at least in one direction,

on part of its course.

  According to the invention, said limiting means preferably act when the piston moves over part of its stroke situated on the side of said radial end wall of the

cylinder.

  According to the invention, said flow means can advantageously comprise means making it possible to avoid said limitation means when the piston moves in its other direction. These means making it possible to avoid the limiting means preferably comprise a valve subjected to the action of a spring. In a preferred variant of the present invention, said radial end wall of said cylinder is provided with a longitudinal projecting part engaged in a cavity of the piston and having a main flow channel for the fluid emerging laterally, so that over part of the piston stroke, the inner wall of the latter's cavity is opposite the peripheral opening of said main flow channel, the space extending between this inner wall of the cavity of the piston and the peripheral wall of said projecting part being such that, on said part of stroke of the piston, the flow of the fluid is limited with respect to its flow

  when the piston is on its other part of the stroke.

  According to the invention, the piston cavity preferably comprises a front part constituting said interior wall and, at the bottom, an interior chamber connected to said fluid chamber

  through a channel in the piston.

  According to the invention, said projecting part preferably comprises a secondary flow channel extending said main flow channel and opening into said interior chamber of the piston, at least when said interior wall of the cavity of the piston is opposite. - screw of the peripheral opening of said main flow channel, a valve preventing the fluid from flowing from the interior chamber of the piston cavity to

the main flow channel ..

  In a variant according to the invention, a ring is mounted in the front part of the cavity of the piston, this ring forming said interior wall of the cavity. This ring can

  advantageously be mounted radially movable.

  According to the invention, the piston preferably carries, at its longitudinal ends, friction rings in

said cylinder.

  In a particular variant, the cylinder carries a toothed wheel engaged with a rack. longitudinal formed on the piston in order to rotate this wheel during the

  longitudinal displacement of the piston.

  The present invention will be better understood from the study of a hydraulic or pneumatic actuating cylinder described by way of nonlimiting example and illustrated by the drawing in which: - Figure 1 shows, in longitudinal section, a cylinder actuation according to the present invention, in which the piston is in its extreme left position;

264 1342

  - Figure 2 shows the cylinder of Figure 1, the piston being in its first intermediate position; FIG. 3 represents the cylinder of FIG. 1, the piston being in a second intermediate position - and FIG. 4 represents the cylinder of FIG. 1,

  the piston being in an extreme right position.

  The actuating cylinder shown in the figures and generally identified by the reference 1 comprises a cylinder generally identified by the reference 2. This cylinder comprises a central cylindrical part 3 as well as two cylindrical end parts 4 and 5 screwed in the part

central 3.

  On the ends of the cylindrical end parts

  mity 4 and 5 of cylinder 2 are screwed from the radial walls 6 and 7.

  In the cylinder 2 is mounted, longitudinally movable, a piston 8, thus forming on either side of the fluid chambers

9 and 10.

  On the peripheral end parts of the piston 8 are mounted friction rings 11 and 12 and seals 13 and 14 which bear against the cylindrical inner wall of the cylindrical end parts 4 and 5 of the

cylinder 2.

  The cylinder 1 also comprises, inside and on both sides of the piston 8, flow means for the fluid, generally identified by the references 15 and 15a, which allow the arrival and the exit of fluid in chambers 9 and 10, through the radial end walls 6 and 7. The means

  and 15a are identical but mounted in opposite directions.

  The flow means 15 comprises a part

  tudinal projection 16, one end of which is screwed into an axial passage through 17 of the radial end wall 6 of the cylinder 2,

this part being cylindrical.

  The longitudinal protruding part 16 is engaged in a cylindrical longitudinal cavity 18 of the piston 8. In the entry part of this cavity 18 is mounted a ring 19 which surrounds the longitudinal protruding part 16, forming between them an annular space 20, this ring being held on the one hand by a shoulder 21 provided in the cavity 18 and on the other hand by a washer 22 fixed against the radial end face of the piston 8, so that the ring 19 is axially movable relative to to the piston 8 in order to absorb any radial movements of the piston 8 relative to the cylinder 2. Behind the ring 19, the cavity 18 of the piston 8 has, at the bottom, an interior chamber 23 which is connected to the fluid chamber 9 per channel

  longitudinal 24 formed in the piston 8.

  In the longitudinal projecting part 16 is formed a main flow channel 25 which comprises a longitudinal channel 26 opening into the passage 17 of the radial wall 6 of the cylinder 2, passage which can be connected to an external fluid conduit, as well as '' a radial channel 27 opening at the periphery of the part

longitudinal projection 16.

  The longitudinal projecting part 16 also has a secondary channel 28 which extends towards the free end of this part 16 the channel 26 of the main flow channel 25 and which has a radial channel 29 opening at the periphery of the longitudinal projecting part 16. In the secondary flow channel 28 is provided a valve 30 closing this channel when it abuts in the direction of the main flow channel 25 on a frustoconical seat 31, this valve 30 being subjected in this sense to a

spring 32.

  The fluid flow means 15 has the arrangements

  following sections. The peripheral opening of the radial channel 27 of the main flow channel 25 is disposed at a distance from an inner annular shoulder forming a stop 33 of the radial end wall 6 of the cylinder 2, formed around the axial passage 17 of this wall 6 As can be seen in FIG. 1, the length of the ring 19 mounted in the cavity 18 of the piston 8 is such that, when the radial end wall of the piston 8 is in abutment against the shoulder 33, this ring 19 covers or extends opposite the peripheral opening of the radial channel 27 of the main flow channel 25. In addition, at least as long as the inner face of the ring 19 mounted in the cavity 18 of the piston 8 stretches opposite

  or opposite the opening of the radial channel 27 of the flow channel-

  main channel 25, the radial channel 29 of the secondary flow channel

  Daire 28 opens into the interior chamber 23 of the piston 8. In addition, the annular space 20 formed between the ring 19 and the peripheral wall of the projecting longitudinal part 16 is such that when this ring 19 covers the peripheral opening of the channel radial 27 of the main flow channel 25, the flow of the fluid is limited relative to its flow when this ring 19 does not cover this opening, that is to say when the piston 8 is distant from the shoulder 33 of the radial end wall 6 of the cylinder 2 at least beyond the peripheral opening of the channel

radial 27.

  As can be seen in the figures, the constituent parts of the flow means 15a, identical and symmetrical to the flow means 15 and provided at the other end of the piston 8,

  bear the same reference figures accompanied by the index a.

  The radial channels 27 and 27a of the flow means and 15a are formed so that the piston 8 has a central stroke in which the rings 19 and 19a provided in the cavities 18 and 18a do not cover the peripheral openings of these channels radials 27 and 27a of the main flow channels

and 25a.

  The cylinder 1 described above operates in the following manner. In the position visible in FIG. 1, the left end of the piston 8 is in abutment against the internal shoulder 33 of the radial end wall 6 of the cylinder 2. If a pressurized fluid is supplied in the passage 17 of the radial end wall 6, by a pipe not shown in the figures, this pressurized fluid pushes the valve 30 against the

  spring 31 and the pressurized fluid flows through the longitu-

  line 26 of the main flow channel 25, through the flow channel-

  secondary ment 28 in the inner chamber 23 of the cavity 19 and flows through the longitudinal passage 24 of the piston 8,

  of the inner chamber 23 of the cavity 18 in the outer chamber

  mite 9. The fluid preferentially flows through this circuit, rather than flowing through the radial channel 27 and the space 20 of the main flow channel 25. The piston 8 then moves to the right, moving away from the radial end wall 6. In doing so, the fluid contained in the other end chamber 10 flows through the main flow channel 25a from the other flow means 15a and is discharged through passage 17a of the other radial end wall 7, by a pipe not shown on

the figures.

  As can be seen in FIG. 2, when the piston 8 has moved longitudinally by the distance separating the peripheral opening of the radial channel 27 from the main flow channel and the shoulder 33 from the radial end wall 6, the ring

  19 provided in the cavity 18 of the piston 8 clears the peripheral opening

  risk of this radial channel 27. It follows that the pressurized fluid flows directly into the end chamber 9 through the main flow channel 25 formed by the longitudinal channel 26 and the radial channel 27 and that the valve 30, under the effect of the spring 32, abuts against its seat 31, thereby closing the secondary flow channel 28. Under the effect of the pressure of the fluid, the piston 8 continues its course to the right in s' moving away from the radial end wall 6, the fluid contained in the other

  end chamber 10 continuing to flow through the flow channel

  main element 25a of the flow means 15a.

  As can be seen in FIG. 3, when the ring l9a of the flow means 15a provided at the other end of the piston 8 meets and covers the peripheral opening of the radial flow channel 27a of the main flow channel 25a, the fluid

  contained in chamber 10 cannot escape through the drainage channel

  main ment 25a towards the outlet passage 17a of the radial end wall 7 only by passing through the space 20a separating the ring 19a provided in the cavity 18a of the piston 8 and the peripheral wall of the longitudinal projecting part 16a carried by the radial wall

  end 7, the valve 30a remaining in abutment against its seat 31a.

  The supply pressure of the chamber 9 does not change, the movement to the right of the piston 8 occurs at a lower speed until the other radial end wall of this piston 8 comes into abutment against the shoulder 33a of the radial wall

  end 7, this extreme position being visible in FIG. 4.

  It appears from the above operation that the movement of the piston 8 from the left to the right in the figures presents, for a supply pressure of the end chamber 9, a first speed of movement during which the fluid contained in the other end chamber 10 is evacuated by the main flow channel 25a and a second speed of movement lower than the first during which the fluid from this chamber 10 is evacuated by the main flow channel a but in passing through the space 20a separating the ring 19a and

  the peripheral wall of the longitudinal projecting part 16a.

  The piston 8 is therefore, in the final part of its movement of

  left to right in the figures, braked.

  To produce the movement of the piston 8 from the right to the left in the figures, the end chamber 10 is supplied through the passage 17a of the radial end wall 7. This supply of fluid to the chamber 10 and the evacuation of the fluid from the chamber 9 occurs symmetrically to what has just been described. This movement from right to left is therefore

also two speed.

  As can be seen in the figures, the central part of the piston 8 has a longitudinal rack 34 which is engaged with a toothed wheel 35 with transverse axis which is arranged in a projecting part 36 of the central part 3 of the cylinder 2 and which is carried by the latter. Thus, during the displacement in one direction or the other of the piston 8, the wheel 35 is driven

  rotating in one direction or the other. Thanks to the means of listening

  Lement particular 15 and 15a, the rotary movement of the wheel 35 can be braked on the end portions of its reciprocating movements. The jack 1 which has just been described can be applied whenever there is a need to brake, at the end of the travel in one direction or the other, the element which the jack is intended to drive. A particularly interesting application is in the field of driving closure elements such as

as doors or gates.

  The cylinder 1 described above comprises at its two ends

  mites the flow means 15 and 15a. It is understood that this cylinder could have only one of these flow means so that the movement of the piston 8 relative to the cylinder 2 would only be braked in the end part of its stroke in a direction of movement and not in its other direction. As described above, the flow means 15, respectively the flow means 15a, is in fact constructed so as to evacuate the fluid from the fluid chamber 9 with which it is associated in a first condition, on part of the stroke of the piston 8, directly through the main flow channel 25 and in a second condition, on a terminal of the stroke of the piston, also through the main flow channel 25 but passing through the space 20 separating the ring 19 from the cavity 18 of the

  piston 8 and the projecting part 16, space 20 in which the

  The fluid is braked. In addition, the flow means 15 is constructed so as to ensure, in the other direction of movement of the piston 8, a supply of fluid to the fluid chamber 9 firstly by the- [secondary flow tanal 28 and then directly through the main flow channel 25, without being braked by the flow means 15, all

along this race.

  In the case where a single flow means is provided, the end of the piston 8 not comprising the flow means

  can carry, in a conventional manner, a longitudinal cylinder rod.

  The present invention is not limited to the example described above. Many variants are possible

  without departing from the scope defined by the appended claims.

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Claims (11)

  1. Actuating cylinder (1) comprising a cylinder (2) of which a piston (8) is longitudinally movable and which comprises between this piston and at least one radial end wall (6) of the cylinder a fluid chamber ( 9) and fluid flow means connected to this chamber, characterized in that these flow means (15) comprise means (19) for limiting the flow of the fluid when the piston (8) moves , at   less in a sense, on part of its course.   2. Cylinder according to claim 1, characterized by! 0 the fact that said limiting means (19) act when the piston moves over a part of its stroke located from the c8té   of said radial end wall of the cylinder.   3. Cylinder according to one of claims 1 and 2, charac-   terrified by the fact that said flow means (15) comprise means (30) making it possible to avoid said limitation means   (19) when the piston moves in its other direction.   4. Cylinder according to claim 3, characterized in that the means allowingK to avoid the limiting means   comprise a valve (30) subjected to the action of a spring (32).   5. Cylinder according to any one of the claims   above, characterized in that said radial wall   end (6) of said cylinder (2) is provided with a longitu-   protruding dinal (16) engaged in a cavity (18) of the piston (8) and having a main flow channel (25) for the fluid emerging laterally, so that on part of the stroke of the piston, the wall interior of the latter's cavity   is opposite the peripheral opening of said flow channel   Mainly, the space (20) extending between this inner wall   lower of the cavity of the piston and the peripheral wall of said projecting part (16) being such that on said part of stroke of the piston, the flow of the fluid is limited compared to its flow when the piston is on its other part race. 6. Cylinder according to claim 5, characterized in that the cavity (18) of the piston (8) comprises a front part (19) constituting said interior wall and, at the bottom, an interior chamber (23) connected to said interior chamber. fluid (9) through a channel (24) formed in the piston (8).   7. Cylinder according to one of claims 5 and 6, charac-   terrified by the fact that said projecting part (16) comprises a   secondary flow channel (28) extending said flow channel   main element (25) and opening into said interior chamber (23) of the piston (8), at least when said interior wall of the cavity of the piston is facing the peripheral opening of said main flow channel, a valve (30) preventing the fluid from flowing from the interior chamber (24) of the cavity (18) of the   piston to the main flow channel (25).   8. Cylinder according to any one of claims   7, characterized in that a ring (19) is mounted in the front part of the cavity (18) of the piston (8), this ring forming   said interior wall of the cavity.   9. Cylinder according to claim 8, characterized by   the fact that said ring (19) is mounted radially movable.   10. Cylinder according to any of the claims   previous, characterized in that the piston (8) comprises, at its longitudinal ends, friction rings (11, 12) in said cylinder (2).   11. Cylinder according to any one of the claims   above, characterized in that the cylinder (2) carries a toothed wheel (35) engaged with a longitudinal rack (34) formed on the piston (8) in order to cause this   wheel during the longitudinal displacement of the piston.