Abstract:
A module comprises a pilot valve and four switching valves, in particular for driving actuators, the pilot valve being a 4/3-way valve.

Description:
The invention relates to a module comprising a pilot valve and four switching valves, in particular for driving actuators. 
     BACKGROUND OF THE INVENTION 
     Such a module may form a 5/3- or 4/3- way valve and makes it possible to drive an actuator, for example, a double-acting hydraulic cylinder. The pilot valves are usually formed by sliding valves, more particularly two solenoid pilot valves. The slider assumes a center position when the pilot valves are not energized, whereas the slider assumes either a first or a second off-center switching position when one or the other pilot valve is driven. A similar or even higher piloting requirement is needed for corresponding diaphragm valves in 5/3- and 4/3- way arrangements. It is especially when these valves are used in in-line valve islands that high complexity results in wiring the solenoid contacts of the pilot valves to a control terminal. 
     The object of the invention is to simplify driving fluid-actuated 5/3- and 4/3- way valves such that all three switching positions of the valves may be switched by a single solenoid of a pilot valve. 
     BRIEF DESCRIPTION OF THE INVENTION 
     This object is achieved with a module comprising a pilot valve and four switching valves, in particular for driving actuators, the pilot valve being a 4/3- way valve. In this way the complication and bulk of the two solenoid pilot valves provided hitherto is reduced to that involved in a single pilot valve, thus facilitating the connection of the valves to valve islands and interlinking such valves to a common power/fluid supply. 
     Advantageous aspects of the invention read from the sub-claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described with reference to various embodiments as shown in the attached drawings in which: 
     FIGS. 1 a ) to  1   d ) are schematic representations of an actuator in various circuit variants; 
     FIG. 2 is a schematic representation of a first circuit arrangement for an actuator; 
     FIG. 3 is a schematic representation of a second circuit arrangement for an actuator; 
     FIG. 4 is a schematic illustration of part of a housing of a pilot element including a control chamber and a sealing part arranged therein; 
     FIG. 5 is a schematic section view of a pilot element; 
     FIG. 6 is a schematic illustration of an actuating member as may be used with the pilot element as shown in FIG. 5; 
     FIG. 7 is a schematic plan view of a switching element as may be used with the pilot element as shown in FIG. 5; 
     FIG. 8 is a schematic cross-section through the two control chambers of the pilot element as shown in FIG. 5; 
     FIG. 9 is a schematic illustration of the first circuit arrangement for an actuator including a pilot element in accordance with a first embodiment; 
     FIG. 10 is a schematic illustration of the first circuit arrangement for an actuator including a pilot element in accordance with a second embodiment; 
     FIG. 11 is a schematic illustration of the second circuit arrangement for an actuator including a pilot element in accordance with a first embodiment; 
     FIG. 12 is a section through a valve island including a pilot element; and 
     FIG. 13 is a detail on a magnified scale of the valve island as shown in FIG.  12 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG. 1 d  there is illustrated the driving of an actuator as will now be described in general, the actuator in this case shown as a double-acting actuator cylinder  1 . The actuator cylinder  1  comprises a piston  2  as well as a working chamber  3  on the left-hand side of the piston  2  and a working chamber  4  on the right-hand side. The working chamber  3  is provided with a port A and the working chamber  4  is provided with a port B. 
     FIGS. 1 a  to  1   c  , show various kinds of driving the actuator cylinder, a 4/3- way valve being employed in each example. In each left-hand switching position the working chamber  3  is pressurized by a fluid at a pressure P, for example compressed air, whilst the right-hand working chamber  4  is connected to a port R serving as return conduit. The piston  2  is thus urged to the right. In each right-hand switching position the working chamber  4  is pressurized by the pressure P via port B, whilst the left-hand working chamber  3  is connected to the return conduit R. The piston  2  is thus urged to the left. 
     These three circuiting examples each differ as regards their center position. In the center position as shown in FIG. 1 a ) a floating circuit is achieved in which the two working chambers  3 ,  4  are connected to the return conduit R, i.e. the piston  2  being freely movable. The circuit example as shown in FIG. 1 b ) achieves in the center position a lockup position in which each of the two working chambers  3 ,  4  is pressurized by the pressure P, i.e. the piston  2  is blocked from moving at all. In the example as shown in FIG. 1 c ), a lockup position is likewise achieved, but in this case each of the two working chambers  3 ,  4  being shut off, i.e. closed. Here too, the piston  2  is blocked. 
     Referring now to FIG. 2 there is described an example for driving an actuator cylinder, in this case solenoid valves M being used as the pilot valves connected to the switching valves S 1  and S 2 . To indicate assignment to the left-hand or right-hand working chamber of the actuator, the solenoid valves and switching valves are indexed L and R, respectively. 
     An energizing voltage U may be applied to the solenoid valves. The switching valves are provided with a pressure port P and with a return port R. 
     Depending on how the solenoid valves M are driven, various driving modes are achievable for the actuator  1  with the circuit as shown in FIG.  2 . These various possibilities are listed in the following Table 1: 
     
       
         
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 U L   
                 U R   
                 S 1L   
                 S 2L   
                 S 1R   
                 S 2R   
                 Operating Mode 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 0 
                 0 
                 P closed   
                 R open   
                 P closed   
                 R open   
                 Drive freely 
               
               
                   
                   
                   
                   
                   
                   
                   
                 movable 
               
               
                 2 
                 L 
                 0 
                 P open   
                 R closed   
                 P closed   
                 R open   
                 Drive to the right 
               
               
                 3 
                 0 
                 L 
                 P closed   
                 R open   
                 P open   
                 R closed   
                 Drive to the left 
               
               
                 4 
                 L 
                 L 
                 P open   
                 R closed   
                 P open   
                 R closed   
                 Drive fixed 
               
               
                   
               
             
          
         
       
     
     In this table, P refers to a pressure port, whereas R refers to an unpressurized return port. 
     The switching conditions  1  to  3  as shown in the Table correspond to those of the circuit as shown in FIG. 1 a ), the switching conditions  2  to  4  correspond to those of the circuit as shown in FIG. 1 b.    
     In FIG. 3 is shown another way of circuiting the actuator  1 , the resulting drive modes of which are listed in the following Table 2: 
     
       
         
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 U L   
                 U R   
                 S 1L   
                 S 2L   
                 S 1R   
                 S 2R   
                 Drive Mode 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 0 
                 0 
                 P closed   
                 R closed   
                 P closed   
                 R closed   
                 Drive fixed 
               
               
                 2 
                 0 
                 L 
                 P closed   
                 R open   
                 P open   
                 R closed   
                 Drive to the left 
               
               
                 3 
                 L 
                 0 
                 P open   
                 R closed   
                 P closed   
                 R open   
                 Drive to the right 
               
               
                 4 
                 L 
                 L 
                 P open   
                 R open   
                 P open   
                 R open   
                 Drive fixed 
               
               
                   
               
             
          
         
       
     
     The switching conditions  1  to  3  as shown in Table 2 correspond to those of the circuit as shown in FIG. 1 c ), the switching condition  4  correspond to P being short-circuited to R. 
     Instead of solenoid valve piloting, requiring the use of various solenoid valves, the same circuit arrangements may be achieved by a single pilot element configured as 4/3- way valve. 
     Referring now to FIGS. 4 to  8  there is illustrated the construction of one such pilot element which will now be described. The pilot element  10  comprises a housing  12  in which two juxtaposed control chambers  20 ,  30  are configured isolated from each other, of which only one is evident from FIG.  4 . Opening into each control chamber is a working port and two pressure ports, the working port being identified by A or B and the pressure ports by P and R, respectively. Two of the ports in each control chamber  20  or  30  are provided with a sealing seat  21 ,  22  and  31 ,  32 , respectively. Cooperating with the sealing seats  21 ,  22  and  31 ,  32  is a switching element identified in general by the reference numeral  14 . The switching element  14  is movable from a resting position into a first and second position by acting on an actuator protuberance  15 . In all, three positions of the switching element  14  are thus possible. For actuating the switching element  14  an actuating member  16  is provided (see more particularly FIG. 6) configured, for example, as a solenoid drive having a polarized drive element, the permanent magnet of which in the non-energized condition of a solenoid causes a center position of the actuator protuberance  15  and in the energized condition shifts the actuating arm in the direction of either arrow  1  or arrow  2  depending on the direction of the current. 
     Referring now to FIG. 6 there are illustrated the two positions  1  and  2  of a magnet  17  applied to the actuator protuberance  15 . The solenoid of the actuating member is identified by the reference numeral  18  and the switchable voltage source is identified in FIG. 6 by the reference numeral  19 . 
     The basic construction of the switching element  14  comprising a core  11  and an elastomer  13  surrounding the latter, as well as the mounting arrangement of the switching element in the housing  12  is known in principle from U.S. Pat. No. 5,711,346 which is incorporated herein by reference. The detailed construction of the switching element can be derived from this patent. 
     Referring now to FIGS. 7 and 8 the functioning of the pilot element will now be described in detail. The switching element  14  protrudes into each control chamber  20 ,  30  with a sealing part  24  and  34 , respectively. The two sealing parts  24 ,  34  are fixedly connected to the actuator protuberance  15  and are moved simultaneously with the actuator protuberance. The two sealing parts  24 ,  30  are arranged at different levels, i.e. mutually staggered, whereas each of the sealing seats  21 ,  31  arranged on the upper side of the control chambers  20 ,  30  and the sealing seats  22 ,  23  arranged on the underside of the control chambers is at the same level. 
     When with reference to the resting position as shown in FIG. 8 the sealing parts  24 ,  34  are urged upwards there is no change in the switching condition as regards control chamber  20  due to the sealing part  24  deforming elastically and continuing to be in contact with the sealing seat  21 , whilst the sealing part  34  in the control chamber  30  is lifted from the sealing seat  32  and pressed against the sealing seat  31 , whereas when the sealing parts  24 ,  34  are urged downwards there is no change in the switching condition as regards control chamber  30  whilst the sealing part  24  in the control chamber  20  is lifted from the sealing seat  21  and pressed against the sealing seat  22 . It will readily be appreciated that differing switching conditions are achievable by suitably swapping the circuiting of the ports. It is also possible to use sealing parts which instead of being mutually staggered are arranged in a single plane when simultaneous use is made of staggered sealing parts  21  and  31  or  22  and  32 . 
     Referring now to FIG. 9 there is illustrated a circuit based on the circuit as shown in FIG. 2 using the pilot element as known from FIGS. 4 to  8  instead of the solenoid valve M as shown in FIG.  2 . This circuit as shown corresponds to the example as shown in FIG. 1 a ). In the starting position as shown in FIG. 9 in which the two pressure ports P of the pilot element are closed, a float circuit is achieved in which the two working chambers of the actuator are connected to R. 
     Referring now to FIG. 10 there is illustrated a similar circuit, except that in this case the circuiting of the ports of the pilot element has been changed. This circuit as achieved corresponds to the example as shown in FIG. 1 b ). In the starting position of the valve element, in which the two return ports R are closed, the piston of the actuator is blocked by pressurization at P on both sides. 
     Referring now to FIG. 11 it is evident that the pilot element as known from FIG. 9 is combined with the circuit of the switching valves known from FIG.  3 . The result is the circuit as known from FIG. 1 c ), whereby in the resting position as shown in FIG. 11 in which the two pressure ports P of the pilot element are blocked, both the two working chambers of the actuator and the ports P, R are closed. 
     Finally, in FIGS. 12 and 13 there is illustrated a valve block achieved by combining the switching valves S with a pilot element as shown in FIGS. 4 to  8 . Clearly evident is the particularly compact construction which is established since only one pilot solenoid is needed, thus making it particularly suitably for use in an in-line valve system with a continuous pneumatic supply terminal and an electric connection terminal for power supply and, respectively, digital pulse driving of the solenoids as is known in field bus technique. In addition to this, a high throughput establishes since only few flow bypasses are needed. Since all pilot components and the switching valves are configured with no friction the arrangement is particularly suitably for systems sealed-for-life (no basic lubrication with dry compressed air) involving low wear and long life.