WO2010035296A1

WO2010035296A1 - Fluid operated actuator

Info

Publication number: WO2010035296A1
Application number: PCT/IT2008/000620
Authority: WO
Inventors: Roberto Turina
Original assignee: Sites S.R.L.
Priority date: 2008-09-29
Filing date: 2008-09-29
Publication date: 2010-04-01

Abstract

Fluid actuator (1) comprising a flexible hose (2) suitable to be pressurized by means of said fluid and compression means (3) of said flexible hose, said compression means (3) being provided with at least two idle rollers (4,5) which surround and, at least when the pressure in said hose varies, roll along the outer surface (6) of said hose for relative movement between said compression means and said flexible hose, characterized in that it comprises a guide (7) integral with said flexible hose and constrained slidingly to said compression means (3).

Description

FLUID OPERATED ACTUATOR OF THE PINCHING ROLLER TYPE

Field of the invention.

The present invention relates to a fluid actuator. In particular, the actuator in question can be employed in devices employed to move a load. Purely by way of example, devices employing this type of actuator can be, for example, elevators, hoists, mechanical arms or industrial manipulators, or sliding gates or other devices in which relative movement between two distinct parts must be ensured. Background of the invention.

According to prior art, these fluid actuators comprise a flexible hose suitable to be pressurized by a fluid, such as water or air, and means to compress said pipe and flatten it, bringing the walls into mutual contact, or almost. It is observed that here and hereafter "flexible hose" is intended to mean a hollow elongated element which can have a cylindrical cross-section, or an oval, polygonal or other similarly shaped cross-section, without however departing from the scope of protection of the present invention. Moreover, the flexible hose can take various configurations according to the pressure therein: at atmospheric pressure it is collapsed on itself; at operating pressure it takes a stable shape which depends on its cross-section. In other words, the hose is produced in a flexible material (as it must be capable of being flattened) but not elastic, as the pressurized cylinder must not be deformed but, on the contrary, act like a rigid cylinder. For example, a flexible hose which acts in the manner described above can be produced in materials such as those used for a fire hose or an air bag, or another similar material. The compression means are generally provided with at least two idle rollers which press on the outer surface of the hose and, following variations in pressure that can be produced inside the hose, roll along the outer surface thereof, so as to perform a relative movement between the compression means and the hose.

In practice, the actuator can be made to operate in two possible modes: maintaining the compression means fixed, for example, by fastening them to the frame of the device on which they are installed, so that when the pressure present therein varies, the hose can be made to slide in relation to the compression means; or keeping the hose still and sliding the compression means with respect thereto.

For example, Japanese patent application JP10299713 describes a water actuator similar to the one described above. In the specific case, the flexible hose is maintained fixed, while the compression means are moved along the hose, carrying the cab of a hoist with them. However, the solution described above has the drawback of being intended for use as emergency elevator and is only utilizable for this purpose. More in general, known actuators with flexible cylinder are difficult to use for applications requiring accurate and repeatable positioning thereof. Summary of the invention The object of the present invention is to provide a fluid actuator which ensures relative movement between the compression means and the hose, which is essentially linear and which at the same time ensures safe connection between pipe and flattening or compression means and precise positioning of the load with respect to the actuator. Another object of the present invention is to produce an actuator which is provided with compression means whose action on the hose can be regulated according to the dimensions and to the thickness of the walls of this hose. These and other objects are achieved by the present fluid actuator comprising a flexible hose suitable to be pressurized by means of said fluid and means to compress or flatten said flexible hose, said compression or flattening means being preferably provided with at least two rollers which surround and, at least when the volume of fluid in said hose varies, roll along the outer surface of said hose to generate a relative movement between said compression means and said flexible hose. The rollers or other compression means define at least two chambers inside the hose: a first chamber houses the fluid and a second chamber is without fluid; moreover, the hose is anelastic, so as to respond to the variations in volume and/or pressure of the fluid therein. In other words, as the fluid is fed to the hose, the pressure therein increases until it is such as to cause relative movement between the hose and said compression means, with consequent sliding of the rollers on the hose.

According to the present invention, the actuator comprises guide means which are integral with said flexible hose and which are also slidingly constrained to said compression means. In this manner, the compression means can slide along a guide, rectilinear or curvilinear, so that the hose is maintained aligned with respect to the compression means. Naturally, also in the case of kinematic inversion, i.e. in the case in which the hose and the guide are movable with respect to the compression means, which are fixed, alignment between flexible hose and compression means is ensured by the presence of said guide.

Preferably, the rollers are idle and opposed, if two rollers are present; there can also be three rollers or two or more pairs of rollers in series for improved fluid seal and separation of the pressurized chamber from the chamber without fluid. According to a preferred aspect of the invention, the guide is a rod, while the compression means comprise a housing inside which this rod slides.

Alternatively, the guide can be a rail, while the compression means can comprise a plurality of wheels that roll along this track, or a slide that slides along a guide comprising a groove. Again according to the invention, at least one of the two ends of the hose is provided with a rigid duct for entry of the fluid. This rigid duct is also connected to the guide so that the guide and the hose are integral with each other.

According to an embodiment of the invention, the hose is rectilinear, while the rigid duct has a longitudinal axis parallel to the longitudinal axis of the guide and coincident with the longitudinal axis of the hose. In this situation the two idle rollers are cylindrical.

Moreover, the fluid actuator also comprises means to regulate the distance between the two idle cylindrical rollers. These regulation means comprise at least one threaded pin which acts orthogonally to the axis of rotation of at least one of said two idle wheels so as to move the two axes of rotation of the two rollers towards each other. Flattening or compression of the hose must in any case be performed so that the fluid located inside the hose cannot pass through the flattened portion of the hose.

In accordance with another embodiment of the invention, the flexible hose is in the shape of a circular arc. In this case, both the rigid duct and the guide are in the shape of a circular arc, and the centres of curvature of the guide, of said rigid duct and of said flexible hose coincide. Unlike the previous embodiment described above, the two idle rollers are conical. In both embodiments, the second of the two ends of the hose can be closed. This configuration, also known as single acting, makes it necessary to provide a system to regulate the pressure of the fluid so as to ensure a pressurization/depressurization cycle of the hose through a single rigid duct. The scope of protection of the present invention also includes the case in which the second end of the hose is connected to the fluid dynamic circuit for regulation of the hose pressure. In this case, there are two rigid ducts, each of which is located at one end of the hose.

By appropriately varying the pressures of the two portions of the hose separated by the compression means, a relative movement can be performed between the compression means and the hose. The operating fluid can be chosen from air and water, or another fluid, as long as it is capable of ensuring an adequate operating pressure. The actuator according to the invention can be applied to any device for movement of a load, in which the load is constrained directly or indirectly to the end of the guide, or to said compression means. In the case in which the load cannot be connected directly to the end of the guide, or to said compression means, the device comprises means to grip said load, such as mechanical grippers, suction cups, vacuum producing means, etc.. These means are constrained to the end of the guide or, alternatively, to said compression means. Brief description of the figures The invention will now be described in greater detail with reference to the drawings attached by way of non-limiting example, wherein: figure 1 is an axonometric view of the actuator according to the invention; figure 2 is a side view of the actuator in accordance with a second embodiment of the invention; figure 3 is a side view of the actuator in accordance with a third embodiment of the invention; figure 4 is a side view of the actuator in accordance with a fourth embodiment of the invention; - figure 5a is a top view of the compression means according to the invention; figure 5b is a sectional view of the compression means of figure 5a; figure 6 is an axonometric view of a mechanical device comprising the actuator according to the invention; Description of embodiments of the invention

With particular reference to these figures, reference 1 indicates the generic fluid actuator according to the invention.

According to a first embodiment of the invention, the fluid actuator 1 comprises a flexible hose 2 suitable to be pressurized by means of air and means 3 to compress the flexible hose 2 and define at least two chambers therein. The flexible hose 2 is produced in an anelastic material, i.e. resistant to deformation by pressure; for example, the type of material employed to produce fire hoses, air bags for motor vehicles and similar products, which is therefore also capable of ensuring a perfect seal, is suitable for the use of the invention. In the embodiment shown, the flattening or compression means 3 are provided with a pair of idle rollers 4 and 5 which engage the outer surface of the hose 2 so as to substantially surround it and define two chambers therein, one chamber housing the pressurized fluid and one chamber substantially without fluid, in general at ambient pressure. When at least the pressure present in the hose 2 varies, the rollers are stressed by the (limited) deformation of the wall of the hose 2 so that they roll along the outer surface of the hose 2. In this manner, the compression means 3 are moved in relation to the flexible hose 2 as a function of the volume of fluid fed to this hose and/or of the pressure present therein. With the term "surround" it is intended that the compression means, i.e. the rollers 3, are capable of compressing the flexible hose along a line that passes through the entire cross section of this hose, so as to bring the two sides of the inner wall of the hose into reciprocal contact and thus block passage of the fluid from one side of the hose to the other with respect to the compression means. Advantageously the actuator 1 comprises a guide 7 integral with the hose 2 and slidingly constrained to the compression means 3.

Again according to the first embodiment of the invention, the guide 7 is a rod 50 (figure 1) which can slide inside a hole or similar housing 8 preferably provided in the compression means 3. In the present case, the compression means 3 are fastened to a generic frame 70, while the rod 50 and the hose 2, integral with each other, are movable with respect to the compression means. Simple kinematic inversion consisting in keeping both the rod 50 and the hose 2 still and making the compression means 3 movable also falls within the scope of protection of the present invention. In accordance with a second embodiment of the actuator 1 , the guide 7 is a track 100 (figures 2 and 4) and the compression means 3 comprise two pairs of wheels 200 which roll along said track 100. Alternatively, in place of the two pairs of wheels 200, the compression means 3 can comprise a slide 300 (figure 3) which slides along a guide 7 comprising a groove 150. Again in accordance with the first embodiment of the invention (figure 1) the hose 2 is rectilinear and is provided, at one end 2a of the hose 2, with a rigid duct 9 through which the pressure of the air present in the hose 2 is controlled.

The other end 2b of the hose is instead kept closed. The rigid duct 9 is connected to the rod 50 by means of a bracket 30 which maintains the longitudinal axes X1 and X2, respectively of the rod 50 and of the flexible hose 2, mutually parallel.

It must be observed that the rod 50 is advantageously arranged in a vertical position so that the hose 2 is taut and is also in a substantially vertical position. This configuration makes it possible to employ only one constraint for the hose 2, i.e. for the end 2a, while in the actuator shown in figures 2 and 3, the second end 2b of the hose 2 must also be made integral with the guide 7 so that the hose is maintained substantially taut and parallel to the guide 2. It is observed that the term taut here and hereafter is intended as a hose which, also in the absence of pressure, is capable of substantially maintaining the same lenght it takes when pressurized. The rigid duct 9 has a longitudinal axis X parallel to the longitudinal axis X1 of the guide 50 and coincident with the longitudinal axis X2 of said hose 2. The two idle rollers 4 and 5 are cylindrical with parallel axes and, when the air pressure present in the hose varies, roll along the surface 6 of the flexible hose 2. The two rollers 3 and 4 engage and press against the hose 2 so that the air cannot pass through the compressed region of the hose. In this manner, one chamber 16 of the hose 2 is pressurized, while the remaining part of the hose 2, which defines a second chamber 17, is completely flattened on itself.

The actuator also comprises means 20 to regulate the distance Y between the two cylindrical rollers 4 and 5 (figures 5a and 5b). These regulation means 20 comprise two threaded pins 21 which act orthogonally to the axis of rotation S of one 5 of said two idle rollers 4 and 5. As will be evident to those skilled in the art, the number of the pairs of idle rollers can also be two or more, without however departing from the scope of protection of the present invention.

In accordance with a further embodiment not shown here, the flexible hose 2 can be in the shape of a circular arc. In this case, the rigid duct 9 and the rod 50 are in the shape of a circular arc, and the centres of curvature of the rod 50, of the rigid duct 9 and of the flexible hose 2 coincide. In this particular case the two idle rollers are conical rather than cylindrical. In this case, too the second end 2b of the hose 2 is closed. In a manner similar to the embodiments shown in figures 2 and 3, the hose is horizontal and has the second end 2b constrained integrally with the rod 50, so that the hose is maintained taut during use thereof.

It must be observed that the embodiments here described have one end 2a of the hose 2 connected to a rigid duct 9 and the other end 2b of the hose closed. This configuration is also called single acting, as the fluid dynamic system which regulates the pressure of the fluid in the hose is in fluid connection with the hose 2 only through the duct 9.

However, the actuator can also be provided double acting, i.e. provided with two rigid ducts 9 each connected to one end 2a, 2b (figure 4) of the hose 2. In this configuration the two ends 2a and 2b of the hose are connected to the same fluid dynamic circuit for regulation of the hose pressure and therefore, by appropriately varying the pressures in the chambers 16 and 17 of the hose 2, mutually separated by the compression means 7, it is possible to perform the relative movement between the compression means 7 and the hose 2. This double acting configuration is employable in all the embodiments described above, both in those in which the hose 2 is in vertical position (figure 1) and in those in which the hose 2 is in horizontal position (figures 2, 3 and 4). The operating fluid can be chosen from air and water, or another liquid or mixture of liquids (for example water and antifreeze), as long as it is capable of ensuring an adequate operating pressure.

The actuator 1 can be installed in a device 40 for moving a load 41 (figure 6).

The load is constrained indirectly to the end 3a of the rod 50 by means of a mechanical gripper 44 to grip the load 41. Alternatively, the load 41 can also be connected directly to the rod 50, or, if the relative motion is inverted, to the compression means 7.

The device 40 also comprises a series 45 of articulated joints which allow the fluid actuator 1 to be moved in the three directions in space so as to offer the user maximum comfort of use.

Finally, the fluid actuator according to the invention can also be employed in elevators, or in hoists, or in manipulators for glass, or in another device in which relative movement between two mechanical parts must be guaranteed with high accuracy and positioning precision.

Claims

1. Actuator (1) comprising a flexible hose (2), a means to feed a fluid to said flexible hose to pressurize it and compression means (3) to compress said flexible hose, wherein said compression means (3) engage said hose to define two chambers and, at least when the volume of fluid in said hose varies, slide along the outer surface (6) of said hose for relative movement between said compression means and said flexible hose, characterized in that said flexible hose is anelastic and in that it comprises a guide (7) secured to said flexible hose and slidingly constrained to said compression means (3).

2. Actuator as claimed in claim 1 , wherein said flexible hose (2) is produced in an anelastic material.

3. Actuator as claimed in claim 1 or 2, wherein said compression means comprise at least one pair of rollers (4, 5).

4. Actuator as claimed in claim 1 , wherein said guide is a rod and said compression means comprise a housing (8) inside which said rod slides.

5. Actuator as claimed in one or more of the preceding claims, wherein said flexible hose (2) is rectilinear.

6. Actuator as claimed in one or more of the preceding claims, wherein at least one (2a) of the two ends (2a, 2b) of said hose (2) is provided with a rigid duct (9) for entry of said fluid, said rigid duct being connected to said guide.

7. Actuator as claimed in claim 6, wherein said rigid duct has a longitudinal axis (X) parallel to the longitudinal axis (X1) of said guide and coincident with the longitudinal axis (X2) of said hose, and wherein said idle rollers are cylindrical.

8. Actuator as claimed in claims 1 to 7, characterized in that it comprises means to regulate the distance between said at least two cylindrical rollers of said compression means.

9. Actuator as claimed in claim 8, wherein said regulation means comprise at least one threaded pin which acts orthogonally to the axis of rotation of at least one of said two idle rollers.

10. Actuator as claimed in one or more of claims 1 to 6, characterized in that said flexible hose is in the shape of a circular arc.

11. Actuator as claimed in claim 10, wherein said rigid duct and said guide are in the shape of a circular arc, and wherein the centres of curvature of said guide, of said rigid duct and of said flexible hose coincide.

12. Actuator as claimed in claim 11 , wherein said two idle rollers are conical.

13. Actuator as claimed in one or more of the preceding claims, wherein the second (2b) of said two ends (2a, 2b) of said hose (2) is closed.

14. Actuator as claimed in one or more of claims 1 to 12, wherein the second (2b) of said two ends (2a, 2b) of said hose (2) is open and comprises a second rigid duct (9).

15. Actuator as claimed in one or more of the preceding claims, wherein the second (2b) of said two ends (2a, 2b) of said hose (2) is connected integrally with said guide (7) so that said hose is substantially taut.