EP0805278B1 - Pneumatic actuating device - Google Patents

Description

The present invention relates to a pneumatic cylinder device comprising a cylinder body, means for supplying pressurized fluid inside this body, a first piston movable in a first axial chamber located at the rear of the cylinder body and, at least, a second movable piston in a second axial chamber located in front of said first axial chamber. The device further comprises a wall of separation of the two axial chambers having an axial bore and a rod connecting piston capable of sliding tightly in this bore. This rod has a bore which opens, on the one hand, into the first axial chamber at the rear of the first piston and, on the other hand, in the second axial chamber at the rear of the second piston. The pistons are connected to a advancement device located at the front of the cylinder body. The pressurized fluid supply means include a gate valve controlled by control means between a first position in which the fluid is directed into at least one axial chamber, behind the piston contained in this chamber, to request the advancement member forward and a second position in which the fluid is directed in at least one axial chamber, at the front of the piston contained in this chamber, to urge the rearward advancement member.

A device of this type is known from the patent granted in the United States under the number 3,485,141. The advancement member can for example be used for stamping or drilling parts, for example metal, by cooperating with a fixed body of suitable shape. It can also, as is the case in the patent granted in the UNITED STATES under n ° 3 410180, wear a head in wedge shape which, as it advances, urges the jaws of pliers into the direction of their closing, while by moving back it allows the opening of these jaws. In this case, the device can be used for hanging cable ties or the like.

It is therefore directly under the action of the fluid that the organ advancement can be requested, either forward or backward.

A device of this type of common use, must be able to be manufactured for as low a cost as possible. So the circuit of circulation of fluid, often compressed air, is as simple as possible without requiring the creation of long ducts of very large dimensions precise. It should also be noted that, particularly in the case where wishes to use such a device to tighten clamps, its handling should be done in a very small space, such as the vehicle.

The fluid circulation circuit of Swiss Patent No. 570,242 is quite complicated. It has a compressed air inlet at the back of the body cylinder, three parallel channels extending forwards, over a length relatively large, two movable slide valves in bores having conical valve seats, and a third slide valve movable in an axial bore. The number of these pieces, as well as their provision, is not compatible with the realization of the device for a relatively low cost and in a small footprint. To allow handling of the device, the actuator body of which is taken in hand by the user, the control means must extend in a region cylinder body center. To make this necessity compatible with a pressurized fluid inlet and the slide valves located at the rear of the cylinder body, the control means of the device described in the patent Swiss number 570.242 consist of a very long and very bulky. This obviously constitutes a cost disadvantage of manufacturing. It should also be noted that the larger the surface of the order is important, the more the risks of untimely manipulation are great.

The present invention proposes to improve the device of the type cited above by remedying the drawbacks mentioned above.

This object is achieved thanks to the fact that the partition wall has a transverse bore in which the slide valve valve is located, a first conduit which connects the transverse bore to a fluid inlet under pressure, a second conduit which connects the transverse bore to the part rear of the second axial chamber, behind the second piston and a third conduit which connects the transverse bore to the front part of the first axial chamber, in front of the first piston, the first and second conduits being connected and isolated from the third leads in the first position of the slide valve, while in the second position of this valve, the first and third conduits are put in communication and isolated from the second conduit.

It is understood that thanks to the invention, the various conduits can be machined in a very simple way in the partition wall, which allows to considerably reduce their length. In addition, this provision allows use of a single slide valve, placed in a single bore in which different fluid circulation conduits open at positions judiciously distributed. It should also be noted that the fact that the drawer of the slide valve is located in the bore, itself formed in the wall of separation, already locates this drawer in a central region of the cylinder body. he is therefore easier to locate the control means of this drawer, also in a central region, which reduces the length.

Preferably, these control means comprise a lever control arranged substantially transversely to the cylinder body and having a first end, connected to this body in the region in the wall of separation and pivoting around a directed pivot axis substantially axially, and a second end adapted to cooperate with one free end of the valve spool.

In this case, the length of the lever (measured axially) is extremely reduced since it is located directly in the region of the wall of seperation. The fact that this lever is directed substantially transversely and capable of being pivotally actuated about a pivot axis directed substantially axially relative to the cylinder body allows however give it enough leverage to make it easily maneuverable. In addition, this provision improves safety by giving the whole a compact shape which limits the risks of snagging and untimely activation.

The invention will be well understood and its advantages will appear better at reading the following detailed description of an embodiment shown by way of nonlimiting example.

• la figure 1 est une vue en coupe axiale d'un dispositif conforme à l'invention montrant l'organe d'avancement dans sa position arrière,
• la figure 2 est une vue en coupe transversale selon la ligne II-II de la figure 1,
• la figure 3 est une vue de dessus de la figure 1,
• la figure 4 est une coupe analogue à celle de la figure 1, montrant l'organe d'avancement en position avant,
• la figure 5 est une section partielle selon la ligne V-V de la figure 1, et
• la figure 6 est une section partielle, analogue à celle de la figure 5, selon la ligne VI-VI de la figure 4.

The description refers to the accompanying drawings in which:

• FIG. 1 is a view in axial section of a device according to the invention showing the advancement member in its rear position,
• FIG. 2 is a cross-sectional view along the line II-II of FIG. 1,
• FIG. 3 is a top view of FIG. 1,
• FIG. 4 is a section similar to that of FIG. 1, showing the advancement member in the front position,
• FIG. 5 is a partial section along the line VV of FIG. 1, and
• FIG. 6 is a partial section, similar to that of FIG. 5, along the line VI-VI of FIG. 4.

Figures 1 to 4 show a pneumatic cylinder device comprising a jack body 10. A first axial chamber 12 is formed in this cylinder body, at the rear of the latter, while a second axial chamber 14 is formed in the cylinder body, in front of the first one. In addition, a third axial chamber 16 is provided in front of the second.

A first, a second and a third piston, respectively designated by the references 18, 20 and 22 are respectively arranged in the first, second and third axial chambers and are movable in these last. These pistons are connected to each other by a rod. More specifically, this rod comprises a first connecting rod 24 which connects the pistons 18 and 20, and a second connecting rod 26, or "rod of additional connection ", which connects the pistons 20 and 22. The axial chambers 12 and 14 are separated by a partition wall 28 which has a bore axial 30 in which the first connecting rod 24 slides. To make this sealed sliding, a seal 32 is disposed in a groove in this bore and cooperates with the external periphery of the rod 24.

Similarly, an additional partition wall 34 separates the chambers 14 and 16. It also has an axial bore, this time designated by the reference 36 in which the second connecting rod slides 26. The sliding is sealed by a seal 38 disposed in a bore groove 36.

The pistons are connected to a advancement member 40 located at the front of the cylinder body. More specifically, this advancement member is fixed at the front end of the rod which connects these pistons, that is to say, in the example shown, at the front end 42 of the second connecting rod 26. To this end, the advancement member has a tapping 44 which cooperates with the threaded end 42 of the rod 26.

In the example shown, the front end 40a of the member advancement 40 is wedge shaped, that is to say it widens rearward.

Support arms 46 are arranged at the front of the jack body. arms 46 are fixed to the front end of the cylinder body using a ring fixing 48 provided with a thread which cooperates with a thread of the front end of the jack body 10. These arms 46 support plates support 50 spaced from each other. Between these plates are mounted two gripper arm 52. Their front ends 52a are shaped as jaws. Their rear ends have rollers of bearing 52b capable of cooperating with the advancement member in the form of corner. By their median parts, the gripper arms 52 are connected to the support plates, each by a pivot axis 54. Springs spacers 56 are arranged inside the gripper arms, in the region axes 54. Thus, when, as is the case in FIG. 1, the member is in its rear position, the springs 56 stress the arms so that their front ends move apart. When, on the other hand as is the case in Figure 4, the advancement member is in its position before, it cooperates with the rollers 52b to spread the rear ends of the arm 52 and consequently bring their front ends 52a which are thus able to tighten a clamp.

The rod 24 has an axial bore 60 which, by its rear end 60a, opens into the first axial chamber 12 behind the first piston 18 and which, near its front end 60b, opens into the second chamber 14 at the rear of the second piston 20. To do this, the hole 60 is, near its front end, connected to a hole transverse 62 opening on the axial peripheral wall of the rod 24 to rear of piston 20.

The rod 24 being connected to a second rod 26, the axial bore 60 still leads to the free end before 60b. The rod 26 has, as for it, also an axial bore, designated by the reference 64, which, by its rear end, is connected to the front end 60b of the axial bore 60 of the first connecting rod 24. The bore 64 further opens into the third axial chamber 16 behind the third piston 22. To do this, it is connected to a transverse conduit 66 which opens on the axial periphery of the second connecting rod 26, behind the second piston 22. By elsewhere, the front end 64b of the bore 64 is closed.

At the rear of the cylinder body 10 is a connection socket 67 to receive the end of a pressurized fluid supply pipe, in general consisting of a hose for supplying air under pressure. This connection is extended forward by a conduit 68 located on the side of the cylinder body and extending axially into the region of the wall of separation 28. The length of this conduit is therefore slightly greater than the length, that is to say to the axial dimension, of the first chamber 12. With the drilling of the connecting rods, it is the only conduit of the device according to the invention which is relatively long.

The means for supplying the pressurized fluid comprise a slide valve visible on the sections of Figures 2, 5 and 6. It should be noted that for the sake of simplification of the drawings, this valve is not fully shown in Figures 1 and 4.

The valve slide 70 can be ordered in a first position which is that of FIGS. 4 and 6, in which the fluid is directed into at least one axial chamber at the rear of the piston contained in this chamber, which makes it possible to urge the forward advancing member 40. The drawer can also be ordered in a second position, which is that of FIGS. 1, 2 and 5, in which the fluid is directed into at least an axial chamber, at the front of the piston contained in this chamber, such so that the advancement member 40 is biased is the rear.

The slide 70 is movable in a transverse bore 72 located in the partition wall 28 between the first and second axial chambers 12 and 14. As best seen in Figure 2, the bore extends parallel to a cylinder body diameter and is separated from the central bore 30 of the partition wall 28. Only the bore 72, without the slide 70, is shown in Figures 1 and 4.

We now describe the different fluid circulation conduits formed in the partition wall 28. As can be seen in FIG. 1, it first comprises a first conduit which connects the bore 72 to the arrival of pressurized fluid. More precisely, this first conduit 75 comprises a first substantially radial section 74 connected to the end front of conduit 68 and extending to a plane P which is a plane of symmetry of the bore 72 parallel to the axis "A" of the cylinder body. It is in this plane P that the cuts of Figures 5 and 6 are made. The first conduit 75 comprises a second section 76 which extends parallel to this plane P and connects the first section 74 to the bore 72. To facilitate its machining, this second section has a part 78 which initially led to one ends (the rear end) of the partition wall 28 and which is closed with a plug 80. The position of the opening of the conduit 76 in bore 72 is shown diagrammatically in FIG. 2.

Referring to Figures 5 and 6, we see that the partition wall 28 has a second conduit 82 which connects the transverse bore 72 to the rear part of the second axial chamber 14. This second conduit 82 has a single axial section. Its rear end opens onto the bore transverse 72 while its front end opens onto the front face 28a of the partition wall 28, which also constitutes the rear face of the axial chamber 14. Whatever the position of the second piston 20 at inside this chamber, the second conduit 82 therefore opens at the rear of this second piston.

The partition wall 28 has a third conduit 84 which connects transverse bore 72 to the front part of the first chamber axial 12. Like the second conduit 82, the third conduit comprises a single axial section. Its front end opens into the bore transverse 72 while its rear end opens onto the rear face 28b of the partition wall 28, which also constitutes the front end of the first axial chamber 12. Consequently, whatever the position of the first piston 18 inside the first axial chamber, the third conduit 84 opens at the front of this piston.

The partition wall 28 is long enough to accommodate these different conduits. Its length is for example of the order of two to three times the diameter of bore 72.

The drawer 70 has a substantially cylindrical body 86 having two swollen zones 88 and 90 provided with seals and separated from each other.

In the first position of the drawer illustrated in Figure 6, we see that the first conduit 75, more precisely its section 76, is put in communication with the second conduit 82, while the third conduit 84 is isolated. On the other hand, in the second position illustrated by FIG. 5, the first and third conduits 75 and 84 are put in communication, while that the second conduit 82 is isolated.

In fact, if we consider the transverse bore 72 from its opening 72a, outside which can extend beyond the free end of the drawer, up to its bottom 72b, it can be seen that the third, first and second conduits 84, 75 (76) and 82 are successively connected to the transverse bore 72.

The openings of these three conduits in the bore are regularly spaced. The spacing between the two bulges 88 and 90 of the body of the drawer is very slightly greater than the spacing between two conduits. Thus, when the slide is advanced towards the bottom of the bore, the conduits 76 and 82 can be put in communication since their openings are between bulges 88 and 90, while conduit 84 is isolated from the two others by the bulge 90. When, on the other hand, the drawer is distant from the bottom of the bore, the openings of the conduits 84 and 76 are located between the bulges 88 and 90 and are therefore put in communication, while the opening of the conduit 82 is isolated from the other two by the bulge 88.

The operation of the device is as follows. When drawer 70 is pushed towards the bottom 72b of the bore 72, which is possible thanks to the fact that the air in front of the bulge 88 can be expelled by the bore 92, the fluid entering through the conduits 68, 74 and 76 can enter the rear of the second chamber 14 through the second conduit 82 of the wall separation 28. This fluid therefore tends to push forward the second piston 20. At the same time, the fluid enters through the bore 62 in the drilling 60 of the rod 24 and is thus led to the rear of the first axial chamber 12, so that its action is also exerted at the rear of the first piston 18. Similarly, the fluid penetrating through the bore 62 is leads to the rear of the third piston 22 through the holes 64 and 66 of the additional connecting rod 26, so that its action is exerted also on the rear face of the third piston 22. The action of the fluid is thus exerted on the three pistons at the same time which increases its efficiency.

It should be noted that means for evacuating the fluid located in the front part of the chambers when the pistons are pushed forward are provided. As regards the first chamber 12, the conduit 84 is placed in communication with the outside by a hole 94 which equips the ring 96 for guiding the rod 98 of the drawer 70. With regard to the chamber 14, the fluid located at the front of this chamber is directly evacuated by a hole 100 made in the wall of this chamber, at its end before. Finally, the fluid located in the front part of the third chamber 16 can naturally vent to the front of this chamber because none sealing system is provided between the advancing member, the arms of support 46 and ring 48.

When, on the other hand, the drawer 70 is pushed back so as to move away of the bottom 72b of the bore 72, position determined by the cooperation in abutment of the bulge 90 and of the ring 96, the air entering through the conduits 68, 74 and 76 can enter the front part of the first axial chamber 12 through the third conduit 84 of the wall 28. Thus, the assembly constituted by the pistons and their connecting rods is pushed backwards by the action of the fluid on the front face of the first piston 18. It is not necessary for this opportunity to multiply the effect obtained by making the fluid act on others pistons. Insofar as the rear parts of chambers 12, 14 and 16 communicate through the holes in the piston rods, the air expelled in these rear parts when the whole is pushed back is found in the part rear of the second chamber 14 and can be driven outwards by the second conduit 82 of the partition wall 28 which, when the drawer is in its second position, communicates directly with the atmosphere by the evacuation hole 92.

The control means of the slide valve include a lever control 102 arranged substantially transversely. As we best seen in Figure 2, this lever 102 has a first end 102a connected to the cylinder body 10 in the region of the partition wall 28. This first end 102a is pivotally mounted around an axis of pivoting 104, better visible in FIGS. 1 and 4 directed substantially along the axis A of the cylinder body. The second end 102b of the lever 102 cooperates with the free end 99 of the drawer 70.

Note that this lever is directly connected to the partition wall 28, and is therefore only located in a central region of the cylinder body. In order to limit the size of the device, the partition wall has a transverse slot 29 in which is housed the first end 102a of the lever. When the second end 102b lever is pushed so as to push the drawer 70 towards the bottom 72b of the bore, the lever 102 is almost entirely contained in the slot 29. In the example shown, to obtain a sufficient lever arm, the first and second ends of the lever are relatively distant one the other. Thus, the lever extends over more than a quarter of the circumference of the cylinder body. It is therefore also the case of slot 29 which receives it in most of it. The lever being bent, the slot 29 is also.

The device advantageously comprises elastic means for naturally urge the drawer 70 into its second position, in which the advancement member is pushed back. This allows you to so that the natural situation of the device is that in which the arms of clamp 52 are inactive, and their actuation requires action positive on drawer 70, action which ceases as soon as we stop handling the the sink. In the example shown, these elastic means are constituted by a simple spring 106 which rests, on the one hand, on the internal face of the enlarged free end 99 of the drawer and, on the other hand, on the external face of the guide ring 96, fixed in bore 72, in which the rod slides 98 from the drawer. We could also provide other types of means elastic, for example a spiral spring possibly arranged between the bottom 72b of the bore and the internal end of the drawer located below the bulge 88.

The device advantageously includes means for damping the movement of at least one of the pistons at the end of the travel stroke, in at least one of the directions of movement of the advancement member. The pistons being connected to each other by the connecting rods, these means dampen in fact the displacement of the assembly constituted by the pistons, their rod and the advancement member.

In the example shown, these damping means are constituted by a bulge 108 made of relatively flexible material, by example of the rubber or similar type, formed on the rear face of the first piston 18. Thus, when the assembly constituted by the pistons and their connecting rod is brought back to the position of Figure 1, this bulge 108 cooperates with the rear face of the first chamber 12.

It is also possible to provide the front face with one of the pistons, for example also the rear piston, of a bulge of the same type for dampen forward movement. In the example shown, the piston 18 in fact comprises a metal core 18a and an outer ring 18b, in relatively flexible material, which surrounds this core and is provided with bulges. It is advantageous that the position of extreme advancement of the assembly, which obviously defines the extreme front position of the organ advancement 40, is very precisely defined so that the active position jaws 52a is also. With this in mind, the device advantageously comprises first stop means arranged in one of the axial chambers, near its front end, and second stop means arranged on the piston which is on this chamber, in the vicinity of the front face of this piston. So the first and second stop means cooperate with each other when the assembly constituted by the pistons, their connecting rod and the advancing member is pushed towards the front, so that they define the position of extreme advancement of this set.

In the example shown, these stop means are very simple since the first stop means are constituted by the front face of the third chamber 16, front face itself defined by the ends rear 46b of the support arms 46, while the second means of stop are constituted by the front face 22a of the third piston 22. It is possible obviously plan to realize these abutment means in another of the axial chambers. However, the precise position of the arms 46 is determined by screwing the assembly ring 48. This makes it possible to define precisely the position of the first stop means, leaving a possibility of adjustment.

To facilitate the movement of the pistons and avoid any risk of grazing, the device advantageously comprises at least one pad annular 110 disposed in the bore 30 of the partition wall 28 and made of a material with a low coefficient of friction. So, this bearing can cooperate with the outer periphery of the connecting rod 24 in facilitating its sliding in the bore. A similar pad 112 is also arranged in the bore 36 of the partition wall additional, when it is present. Of course, the fact of providing these bearings does not exclude the provision of seals 32 and 38 in the bores.

The peripheral faces of the different pistons cooperating with the axial walls of the chambers, are provided with seals 118, 120 and 122. The front and rear ends of the connecting rods 24 and 26 cooperate by screwing. To wedge the pistons on these rods, wedging washers 124 equip the rear faces of pistons 20 and 22. The rear end of the rod 24 is threaded. The rear face of the first piston 18 has a recess 126 adapted to receive a nut 128 for fixing screwed on the rear end of the rod. The position of the piston relative to the rod is wedged using a wedging washer 130 located on the front face of this piston and cooperating with a shoulder of the rod.

Finally, it should be noted that the cylinder body has three elements main consisting of blind tubes. The first tube 132 defines the first chamber 12. These rear and side walls have the connection pipes at the pressurized fluid inlet. The cavity of the second tube 134 forms the second axial chamber 14. The rear wall of this tube constitutes the partition wall between the chambers 12 and 14. It is therefore it which is provided with bore 72 and the various conduits previously mentioned. This wall is connected by screwing at the end front of the first tube 132. Similarly, the cavity of the third tube 136 forms the third axial chamber 16, while its rear wall forms the wall 34 of separation between chambers 14 and 16. This rear wall is screwed into the front end of the second tube 134. Of course, to guarantee the tightness of the chambers, seals 138 are arranged in the screwing area between the different tubes.

Claims (8)

1. A pneumatic actuator device comprising an actuator body (10), means for feeding fluid under pressure to the inside of said body, a first piston (18) movable in a first axial chamber (12) situated at the rear end of the actuator body, and at least one second moving piston (20) in a second axial chamber (14) situated in front of said first axial chamber, the device further comprising a separation wall (28) separating the two axial chambers, and having an axial bore (30), and a link rod (24) linking together the pistons (18, 20) and suitable for sliding in sealed manner in said bore, said rod having a bore (60) which opens out firstly into the first axial chamber (12) behind the first piston (18), and secondly into the second axial chamber (14) behind the second piston (20), the pistons being connected to an advance member (40) situated at the front of the actuator body (10), and the means for feeding fluid under pressure including a slide valve (70, 72) controlled by control means to move between a first position in which the fluid is directed into at least one axial chamber behind the piston contained in said chamber so as to urge the advance member forwards, and a second position in which the fluid is directed into at least one axial chamber in front of the piston contained in said chamber so as to urge the advance member backwards,
      the device being characterized in that the separation wall (28) has a transverse bore (72) in which the slide of the slide valve (70) is housed, a first duct (74, 76) which connects the transverse bore (72) to a pressurized fluid feed (67, 68), a second duct (82) which connects the transverse bore (72) to the rear portion of the second axial chamber (14) behind the second piston (20), and a third duct (84) which connects the transverse bore (72) to the front portion of the first axial chamber (12) in front of the first piston (18), the first and second ducts (74, 76; 82) being put into communication with each other and isolated from the third duct (84) when the slide (70) of the slide valve is in the first position, while the first and third ducts (74, 76; 84) are put into communication with each other and isolated from the second duct (82) when the slide is in its second position.
2. A device according to claim 1, characterized in that the means for controlling the slide valve (70, 72) comprise a control lever (102) disposed substantially transversely, said lever having a first end (102a) connected to the actuator body (10) in the region of the separation wall (28) and mounted to pivot about a pivot axis (104) that extends substantially axially, and a second end (102b) suitable for co-operating with a free end (99) of the slide (70) of the slide valve.
3. A device according to claim 1 or 2, characterized in that it includes resilient means (99) for urging the slide (70) of the slide valve naturally into its second position.
4. A device according to any one of claims 1 to 3, characterized in that the transverse bore (72) includes an end wall (72b) and an opening (72a) remote from said end wall, beyond which the free end of the slide (70) of the slide valve is suitable for projecting, and in that the third, first, and second ducts (84, 76, 82) are connected in succession to said transverse bore (72) in the direction going from the opening (72a) towards the end wall (72b) of said bore (72).
5. A device according to any one of claims 1 to 4, characterized in that it includes means (108) for damping movement of at least one of the pistons at the end of a displacement stroke, in at least one of the displacement directions of the advance member.
6. A device according to any one of claims 1 to 5, characterized in that it includes first abutment means (46b) disposed in one (16) of the axial chambers (12, 14, 16) in the vicinity of the front end thereof, and second abutment means (22a) disposed on the piston (22) situated in said chamber in the vicinity of the front face of the piston, the first and second abutment means being suitable for co-operating mutually to define the extreme position to which the advance member (40) can be advanced.
7. A device according to any one of claims 1 to 6, characterized in that it includes at least one annular bushing (110) disposed in the axial bore (30), the bushing being made of a material having a low coefficient of friction and co-operating with the link rod (24).
8. A device according to any one of claims 1 to 7, characterized in that it includes a third piston (22) movable in a third axial chamber (16) situated in front of the second axial chamber, an additional separation wall (34) separating the second and third axial chambers (14, 16) and having an axial bore (36), and an additional link rod (26) interconnecting the second and third pistons (20, 22) and suitable for sliding in sealed manner in said axial bore, said additional link rod having a bore (64) connected to the bore (60) in the link rod (24) between the first and second pistons (18, 20), and opening out into the third axial chamber (16) behind the third piston.

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