WO2006037598A1

WO2006037598A1 - An electromagnetic pilot device, in particular for pneumatic valves

Info

Publication number: WO2006037598A1
Application number: PCT/EP2005/010651
Authority: WO
Inventors: Silvano Piccinini
Original assignee: Kpm S.P.A.
Priority date: 2004-10-05
Filing date: 2005-10-04
Publication date: 2006-04-13
Also published as: EP1800039A1; ITMO20040263A1

Abstract

The invention relates to an electropilot device, in particular for distribution valves for pneumatic or hydraulic circuits, comprising a drive, operated by a lever, fitted into a containment compartment positionable at one end of the valve body and endowed with openings connecting with said valve to suitably aim the driving fluid of the mobile casing of said valve. The device controls the passage of the fluid through said openings by operating the lever-operated drive by means an electromagnet positioned at one end of said lever. The dimensions of the lever-operated drive and the relative control electromagnet are such that they allow the potential positioning, in the same compartment, of a second drive for bistable piloting of the valve.

Description

AN ELECTROMAGNETIC PILOT DEVICE , IN PARTICULAR FOR PNEtJMATIC VALVES

Technical field

The invention relates to a pilot device for drives which is useful specifically, but not exclusively, for servo-assisted pneumatic or hydraulic distribution valves.

It also relates to pneumatic or hydraulic distribution valves comprising a particular pilot device.

Background Art

As it is commonly known, pneumatic drives, used widely in various industrial sectors and many everyday applications, comprise actuating cylinders driven by means of compressed air which is suitably filtered and regulated in special circuits comprising specific filtering and regulation devices, and is, moreover, aimed in the direction of the cylinder, or cylinders, by means of variously configured distribution valves.

These valves in particular, as can be seen in Fig.l, are constituted of a prismatic body 1 comprising various openings 2 through which the pressurised fluid can enter or leave the valve.

Said openings are connected externally to supply/draining circuits for the pressurised fluid and to one, or more, actuating cylinders, which are therefore driven, or not, depending on the distribution configuration created inside the valve body 1 as a result of the position of the slide valve 3. The example in Fig.l refers exactly to a valve driven by electropneumatic means, with a spring return. At the two opposing ends of the valve there are, in fact, on one side, a device 4, of the solenoid kind, designed to cause, by means of the said pressurised fluid, the movement of the small cylinder, or spool 5, inside the valve body and which operates the slide valve 3, while, on the other side, there is a spring 6 which ensures the slide valve's position in the configuration illustrated in the figure is kept stable once the pneumatic action on the spool 5 has ceased. The distributing valve operation is, in this case, monostable.

In the event, though, that instead of the spring 6, there is a second pilot device similar to the device 4, the operation obtained is bistable, i.e. a form of operation in which there is no preferential distribution configuration, but both the configurations obtainable are kept stable once they have been selected by means of the operation of the suitable pilot device.

As can be seen in Fig.l, the pilot device 4 is mounted coaxially to the distributing valve body 1 and envisages two holes 7, 8, also coaxial, which are alternately closed or opened by means of a small cylinder 9 integral to the nucleus of a solenoid 40 located centrally in the said device. One of the aforesaid holes 8 creates a connection between the internal compartment of the device 4 and the pressurised fluid supply circuit, while the other hole 7 creates a connection between said compartment and the exterior. It is important to stress the fact that the holes 7 and 8 must be only opened alternately so that there are no doubts concerning the operation of the distributing valve and, therefore, rapid and safe actuation is obtained as regards (he external actuator cylinder controlled by said valve. To guarantee the above, it is necessary for the small cylinder 9 's work stroke to be extremely limited and, parallelly, for the working of the various parts comprising the device to be extremely precise; furthermore, the closing force developed by the solenoid must be sufficiently high and the movement of the nucleus extremely rapid.

All of this obviously effects the manufacturing costs of the pilot device and the relative overall dimensions. Consider that, on average, in current pneumatic distribution valves with bistable operation, the cost of the pilot devices alone is fifty percent of the valve cost and the total dimensions are twice as much those of ihe valve body alone.

Considering that many practical applications require several valves operating adjacently, one can imagine the need to develop innovative solutions relating to the pilot systems for said valves. Disclosure of Invention The main aim of this invention is to propose a pilot device, m particular for pneumatic distribution valves, with which the aforesaid limits can be overcome.

A further aim of the invention is to propose a pilot device for drivers in general which offers features including high efficiency and reliability. The aforesaid aims and further aims besides are achieved by means of a pilot device, in particular for pneumatic or hydraulic distribution valves, characterised by the fact that said device comprises at least one lever-operated drive fitted into a container positionable at one end of the valve body and provided with openings that connect with the exterior and cavities present in said valve to aim the driving fluid from the valve's mobile casing, said lever- operated drive envisaging, at one end, small pads made of rubber, or a similar material, to control access of said openings to an internal compartment of said container and, at the other end, said drive being connected with an electromagnetic actuator.

The lever-operated drive, in the resting condition, is maintained in a preferential configuration by elastic means interacting between the lever and the internal walls of the container; in said configuration, the container's internal compartment is connected, on one side, with the piston of the distributing valve casing and, on the other side, with the bleed opening, while the access to the said opening connecting said compartment with the pressurised fluid adduction piping is kept closed.

As soon as the electromagnet is energised, the lever-operated drive moves into a configuration in which the draining opening in the container's internal compartment is closed while the inlet opening for the pressurised fluid is open; said fluid, flowing through a third opening present in said compartment, operates the valve piston, causing the relative slide valve to move.

The pilot device in question in this invention proves extremely advantageous with respect to the commonly known devices thanks to the fact that all me mechanical precision working currently required is eliminated; what is more thanks to the favourable ratio between the lever arms and the power engaged, the dimensions of the electromagnet are therefore greatly reduced in relation to the dimensions of an electromagnet employed in a traditional pilot device for similar valves.

In the event mat these must be bistable operation valves, two lever-operated drives, with the relative control electromagnets, can be housed in the same container, with clear advantages in terms of the cost and reduction of overall dimensions obtainable with the device according to the invention. These and other advantages of a general nature will better emerge in the detailed description that follows of a preferred embodiment shown, purely in the form of a non-limiting example, in the drawings enclosed, in which:

- Figure 1 shows a view of a longitudinal section of a distributing valve for pneumatic drives fitted with a traditional pilot device;

- Figure 2 shows, a schematic view of a longitudinal section of a similar valve to mat of Fig.l, fitted with a pilot device according to this invention;

With reference to Figure 2, 10 is the complete pilot device for drives according to the invention.

This is linked, in this embodiment, with a distributing valve 11 for pneumatic circuits. Similarly to the valve in Fig.l, also in this case the distribution of the flows between the valve inlets and outlets 12 is regulated by means of a casing 13 located along the longitudinal axis of said valve and driven by a cylinder, or spool 14, integral to one end of said casing. Also in this case, the valve is of the monostable type, since the other end of the casing 13, is fitted with a spring 30, which works so as to place the casing in the position shown in the figure. The movement of the casing 13 into the opposite position is obtained at the moment the pressurised fluid begins its action, having been suitably aimed at the upper surface of the piston 14 by means of the device 10, through an opening 15 of the container 16, the said opening being located in position with an opening 17 in the valve body connecting with said piston 14. In this embodiment of the invention, in addition to the opening 15, in the container 16 there are two further openings envisaged 18, 19, which open into an internal compartment 20 of the container, connecting respectively with an adduction conduit 21 for the pressurised fluid, and with the device's exterior. A lever-operated drive 22, with fulcrum at 23, comprises, at one of its ends, two small pads 24, 25, of a polymeric material or similar, respectively designed to obstruct the openings 18 and 19. The aforesaid end is subjected to the action of the elastic means 26, which interact between the lever and an internal wall of the container 16 to bring the drive into the preferential position shown in the figure when, at the other end of said drive, there is no action exerted by the electromagnet 27, whose nucleus 28 is constrained by means of a joint to the lever 22. In the above position, the small pad 24 is in contact with the opening 18 designed for the adduction of the pressurised fluid into the compartment 20, therefore the aforesaid compartment is connected to the outlet 19 and therefore the piston 14, and Ae casing 13 integral to the latter, assume the position shown in Fig.2 thanks to the action of the spring 30. At the moment that, by means of the external terminals 29, power is supplied to the electromagnet 27, said electromagnet exerts a recalling action on its own nucleus 28 and consequently, a force of a sufficient degree to overcome the action exerted is applied to the lever 22, at the other end, by the elastic means 26. Note that, thanks to the favourable ratio between the distances between the two ends of the lever and the fulcrum 23, a relatively limited recall action exerted on the electromagnet 27 is sufficient to guarantee the movement of the drive operated by the lever 22. In the position assumed by said drive further to the supply of power to the electromagnet 27, the small pad 25 comes into contact with the opening 19, obstructing it, while the other small pad 24 vacates the access to the compartment 20 for the pressurised fluid coming from the adduction conduit 21. This results therefore in the movement of the piston 14 and the casing 13 connected to the latter, thanks to the action exerted by the pressurised fluid on the surface of said spool. Once die power supply to the electromagnet 27 has ceased, the pilot device 10 returns to the configuration in Fig. 2 and the same occurs for the slide valve 13, given the presence of the spring 30, confirming, in this way, the monostable operation of the valve 11 and the relative pilot device 10. Obviously the valve's bistable operation can be obtained using a similar device to the device 10 instead of the spring 30, where the slide valve is connected, also at its other end, with a further piston, or spool, similar to the piston 14. However, considering the limited dimensions of the lever-operated drive and the relative actuator electromagnet, a bistable operation valve can be realised by employing a pilot device according to the invention in which a single container comprises two lever-operated drives, and relative actuators, housed in two adjacent internal compartments which are reciprocally connected with the two pistons positioned at the two ends of the slide valve. Note that, by virtue of the limited dimensions, further lever-operated drives and relative actuators can be housed in the container of the pilot device subject mater of the present invention.

It is likewise obvious that variants and modifications relating to the monostable version of the device described above are possible without affecting the main advantages of this device with respect to the traditional devices. For example, the typology and arrangement of the elastic means which perform their action on the lever-operated drive included in the device could be altered.

Likewise, the conformation of the device and the arrangement of the various openings in the device and the various components could be altered depending on the conformation of the valve to which it is associated. The latter, as already mentioned, could be of either the pneumatic or the hydraulic type. Other types of valves, such as, for example, membrane valves, can be piloted by the device according to the invention.

Further modifications of a practical-applicative nature regarding (he construction details can obviously be applied to the invention while still remaining within the scope of the invention as claimed below.

Claims

1. A pilot device (10), in particular for distribution valves for pneumatic or hydraulic circuits, characterised by the fact that said device comprises at least one lever-operated drive (22) fitted in a container (16) positionable at one end of a valve body (11) and endowed with openings (15, 18, 19) connecting with the exterior and with conduits, or cavities (17, 21) present in said valve body to aim the driving fluid of the mobile valve organ, said lever-operated drive envisaging, at one end, small pads made of rubber, or a similar material (24, 25) designed to control access of one or more of said openings to at least one internal compartment (20) of said container (16) and, at the other end, said device being connected with at least one electromagnetic actuator (27).

2. A pilot device (10) according to the previous claim, characterised by the fact that said device comprises elastic means (26) exerting an action on the lever-operated drive (22) to position said drive in a preferential position when the electromagnetic actuator (27) is de-energised.

3. A pilot device (10) according to the previous claim, characterised by the fact that in said preferential position, one of said small pads (24, 25) obstructs the opening (18) connecting with an adduction conduit (21) for the adduction of the pressurised fluid into the internal compartment (20) of said container (16), said internal compartment of the container connecting, on one side, with the conduit (17) for access to the piston (14) on the valve slide valve and, on the other side, with the bleed opening (19).

4. A pilot device according to claim 2 or 3, characterised fey the fact that, as soon as the electromagnetic actuator (27) is energised, the ϊever- operated drive (22) moves into a configuration in which one of said small pads (24, 25) obstructs the opening (19) for draining the internal compartment (20) of the container, while the other small pad (24) vacates the Met opening (18), in said compartment, for (he pressurised fluid, which, flowing through a third opening (15) present in said internal compartment, operates the piston (14) on (he valve, causing the movement of the relative slide valve (13).

5. A pilot device according to any of the previous claims, characterised by the fact that said lever-operated drive (22) has a fulcrum in a point (23) which ensures the arm of the lever (22) fitted with said small pads (24, 25) is smaller in size than the arm of the lever which connects with said electromagnetic actuator (27) .

6. A pilot device according to any of the previous claims, characterised by the fact that said device comprises two or more lever-operated drives, and relative electromagnetic actuators, housed in two or more adjacent internal compartments of the container.

7. A distributing valve (11), for pneumatic or hydraulic circuits characterised by the fact that said valve comprises at least one pilot device according to any of the previous claims.

8. A pilot device (10), in particular for distribution valves for pneumatic or hydraulic circuits, and distribution valves comprising pilot devices according to the previous claims and in accordance with the statements and illustrations above with reference to the figures in the enclosed drawings and to achieve the aims outlined above.