GB2254132A

GB2254132A - Control mechanism for valves

Info

Publication number: GB2254132A
Application number: GB9206448A
Authority: GB
Inventors: Klaus Pontius; Manfred Settinger
Original assignee: Kloeckner Ferromatik Desma GmbH
Current assignee: Kloeckner Ferromatik Desma GmbH
Priority date: 1991-03-28
Filing date: 1992-03-25
Publication date: 1992-09-30
Anticipated expiration: 2012-03-25
Also published as: DK41392A; FR2674475B1; DE9103853U1; ITMI920286A1; GB2254132B; DK173997B1; GB9206448D0; DK41392D0; ITMI920286A0; FR2674475A1; IT1254782B

Abstract

A valve control mechanism for valves A1, B, A2 arranged to work substantially simultaneously, for example for supplying plastics components to a mixing chamber 1 of a mixer head. The mechanism allows two pairs of valves A1, B and A2, B to share a common valve B. Each pair of valves is actuated by an actuator and arm arrangement KA1, H1 and H2 and KA2, H3 and H4 respectively. The arms H2, H3 operating the common valve B pivot about points L2, L3. Their ends E1, E2 are received freely in an elongate axial slot L in valve rod SB. Slot L provides a lost motion arrangement (Fig 3) that allows either arm to operate the valve B without requiring the other arm to move. <IMAGE>

Description

Control Mechanism For Valves The present invention relates to a control mechanism for valves, suitable for simultaneously controlling valves supplying different plastics components to the mixing chamber of a mixer head.

In known arrangements each of the valves has a valve rod for opening and closing the plastics supply means and the valve rods are coupled in pairs to a double-lever system, the valve end of each of the two lever arms of the double lever being linked to the associated valve rod of one of the valves of the pair of valves, and the double lever being. actuated by means of a fluid-actuated cylinder whereof the piston acts simultaneously on both lever arms of the double-lever system.

In the case of a control mechanism of the type mentioned at the outset, it is known to feed two plastics components simultaneously by actuating the double-lever system. However, this system is limited to the simultaneous feeding of two components and only makes it possible to actuate one pair of valves. This is particularly disadvantageous if, for example, three plastics components are to be fed to a mixing chamber simultaneously and feeding is to be kept precisely synchronous by an enforced control of the component supply.

According to the present invention there is provided a control mechanism for valves as defined in appended claim 1.

Preferred embodiments of the invention are defined in the other appended claims.

It is thus possible to further develop the control mechanism mentioned at the outset such that it simultaneously selects and synchronously supplies more than two plastics components or indeed two or more components from a plurality of components.

A double-lever system is provided for controlling at least two adjacent pairs of valves between each of the pairs of valves to be controlled, and in that the valve ends of the lever arms of the two adjacent double-lever systems are guided against the valve rod lying between them such that they are movable in the same direction when the double-lever systems on either side of the valve are actuated in the same direction and are movable in opposite directions to one another when the double-lever systems on either side are actuated in opposite directions, and in either case transfer the valve rod to the open position of the valve respectively.

In accordance with an embodiment of the invention, the guideway for the inner ends of the double-lever systems in the valve rod is constructed as an elongate hole which extends along the valve rod, the inner ends, in the shape of webs, of both sides engaging in the elongate hole and lying next to one another therein perpendicular to the direction of the elongate hole, and the inner ends overlapping completely when the adjacent double levers are actuated in the same direction and partially when they are actuated in opposite directions.

In accordance with another embodiment, the inner ends of the double-lever systems may engage in two separate elongate holes of the valve rod or be provided with attachment pieces which engage in channels or grooves of the valve rod which enable the ends to move parallel to the axis of the valve rod.

When only a single common elongate hole is used, the inner lever ends may be constructed as stepped attachment pieces whereof the thickness dimension is reduced with respect to the lever thickness by the width of a step, the inner ends lying next to one another between the steps in the interior of the elongate hole.

The invention has the advantage that, as with the known valve controls of the type mentioned at the outset with enforced control, feeding of the plastics components remains guaranteed even with three or more components, and a substantially greater breadth of variation in the selection from a plurality of components is made possible, it even being possible to feed an odd multiple number of components synchronously.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 illustrates diagrammatically a plastics mixing chamber having an embodiment of a valve controller according to the present invention in cross-section perpendicular to the axis of the mixing chamber; Figure 2 is a perspective illustration of the example embodiment illustrated in Fig. 1; Figure 3 illustrates, on an enlarged scale and in perspective view, the detail bordered by a dashed line and designated I in Fig. 1, and Fig. 3' illustrates an enlarged sectional diagram of the detail with the line of section perpendicular to the axis of the valve rod; and Figure 4 illustrates a second example embodiment of the invention.

Figure 1 illustrates the valves Al, B and A2, by means of which the supply of the three different plastics components through the chamber wall 2 to the mixing chamber 1, constructed as a central bore, is controlled.

Below, the plastics components are designated Al, B and A2, as are their respective valves by means of which the supply of these components is controlled.

Mounted in the axial direction in the valves Al, B, A2 are valve rods SA1, SB and SA2. The closing movement, effected by them in the direction of the mixing chamber, is effected by springs F which are mounted in the interior of the valve housing and of which only the spring represented in valve B is illustrated. The opening movement of the valve rods is effected by means of the double-lever systems C1 and C2. Here, the actuator ends of the two levers H1 and H2 of the first double lever C1 engage in the piston attachment piece KA1 and the two actuator ends of the two levers H3 and H4 of the double-lever system C2 engage in the piston attachment piece KA2 of a piston-and-cylinder drive, and are mounted articulatedly in these piston attachment pieces.

The opening movement of the double systems C1 and/or C2 is effected by compressed air being introduced into the cylinders Z1 and/or Z2 and pressing inwards the piston K1 and/or the piston K2 (not illustrated) and thus the piston attachment pieces KA1 and KA2. Here, the two levers H1 and H2 of the first lever system C1 are pivoted about the axes of mounting L1 and L2, while the double levers H3 and H4 are pivoted about the axes of nounting L3 and L4 of the double-lever system C2.Here, the ends of the two levers H1 and H2 are displaced on actuation of the compressed-air cylinder Z1 of the double-lever system C1, as a result of which the valve rods SA1 and SB are moved outwards to open the associated valves. This has the result that when the double-lever system C1 is actuated the plastics component Al and B are opened simultaneously and when the double system C2 is actuated the plastics component B and A2 are opened simultaneously and the corresponding components reach the mixing chamber 1 simultaneously.

The two inner ends El and E2 of the double-lever system C1 and C2 respectively engage in an elongate hole L of the two opposite sides of the valve rods SB therein, and as can be seen from Fig. 3, lie next to one another perpendicular to the extent of the elongate hole and overlap. If both double-lever systems C1 and C2 are actuated simultaneously, the inner ends El and E2 of the two double-lever systems move upwards in the same direction and displace the valve rod SB into the opened position so that, in addition to the components Al and A2, the plastics component B is fed to the mixing chamber by opening all three valves. If only one lever system, e.g.C1, is controlled for valve opening, then the valve B is opened only by the inner end El, which then moves in the opposite direction to the inner end E2, which remains in the position in which the double-lever system C2 is located, which is held in the closed position by the spring.

All in all, the result is the possibility of supplying two respective components, that is to say Al and B or A2 and B, on actuation of only one double-lever system or indeed to supply all three components Al, B and A2 simultaneously on actuation of both double-lever systems, that is to say transfer thereof to the open position of the valves. Here, the elongate hole L must have a length which is adequate for the stroke of movement in opposite directions of the ends El and E2. However, the web width of the ends El and E2 should here be large enough for the webs lying next to one another still to overlap even if the two inner ends are in the opposite limit positions, that is to say if one of the double-lever systems is in the opened position and the other of the double-lever systems is in the closed position.This corresponds to the case where only one of the double systems carries out the supply of two respective plastics components simultaneously.

In order that the size of the elongate hole L can be kept as small as possible, it is recommended to taper the ends El and E2 with respect to the levers by means of one step each, as is achieved by the two steps T1 and T2 which are visible in the perspective drawing of Figures 3 and 3'.

In the embodiment of Fig. 1, two further valves F1 and F2 are also illustrated. These individually controlled valves are used to feed for example ink components to the mixing chamber. Such an arrangement may be chosen in particular if synchronization of the supply of the ink component is not absolutely critical.

A further embodiment of the invention is illustrated in Fig. 4. Here, the six valves V1 to V6 illustrated are divided into two groups offset by 1800, the function of which corresponds to the group of three in accordance with Fig. 1. The reference numerals corresponding to Fig. 1 have been left out, with the exception of the reference numerals V1-V6 for the valves or components.

Claims

1. A control mechanism for a valve arrangement including first, second and third valves having respective first, second and third valve operating members moveable between closed and open positions corresponding to closed and dpen conditions of the respective valves, said control mechanism comprising: a first actuator arranged to move the first and second valve operating members to their respective open positions; and a second actuator arranged to move the first and third valve operating members to their respective open positions, said valves being arranged such that, in use, the first valve is open if either the. second valve is open, the third valve is open, or the second and third valves are open.

2. A control mechanism as claimed in claim 1, in which a first lever movable by the first actuator is arranged to cooperate with a first stop on the first valve operating member to urge the first valve operating member to open the first valve, and a second lever movable by the second actuator is arranged to cooperate with a second stop on the first valve operating member to urge the first valve operating member to open the first valve.

3. A contrdl mechanism as claimed in claim 2, in which the ends of the first and second levers cooperating with the first valve operating member are guided by the first valve operating member.

4. A control mechanism as claimed in claim 2 or claim 3, in which the first and second levers slidably engage in an elongate hole in the first valve operating member, said elongate hole being substantially parallel to the longitudinal axis of the first valve operating member.

5. A control mechanism as claimed in claim 4, in which the ends of the first and second levers lie side by side in the elongate hole and at least partially overlap.

6. A control mechanism as claimed in claim 2 or claim 3, in which the first and second levers slidably engage in respective elongate recesses in the first valve operating member, said elongate recesses being substantially parallel to the longitudinal axis of the first valve operating member.

7. A control mechanism as claimed in claim 6, in which said respective recesses are holes.

8. A control mechanism as claimed in any one of claims 2 to 7, in which at least one of the first and second levers has an end portion of reduced thickness.

9. A control mechanism as claimed in any one of claims 2 to 8, in which at least one of the first and second levers has an attachment piece or lug to engage the first valve operating member.

10. A control mechanism as claimed in any one of claims 2 to 9, in which the first valve operating member guides the first and second levers such that they move in the same direction when the first and second actuators are actuated in the same direction.

11. A control mechanism as claimed in any one of claims 2 to 10, in which the respective actuators operate the associated valves via a respective double lever system.

12. A control mechanism as claimed in any one of claims 2 to 11, in which the levers are tiltable relative to their respective actuators.

13. A control mechanism as claimed in claim 1, in which at least one of the respective first and second levers is in limited slidable engagement with the respective actuator.

14. A control mechanism as claimed in any one of the preceding claims, in which at least one of the actuators is a fluid operated actuator.

15. A control mechanism as claimed in any one of the preceding claims, in which at least the first valve operating member is biased to the closed position by a spring.

16. A control mechanism as substantially hereinbefore described with reference to figures 1 to 3 of the accompanying drawings, or as modified by figure 4 of the accompanying drawings.

17. A mixer head for plastics, comprising at least three valves and a control mechanism as claimed in any one of the preceding claims.