Abstract:
A fluid control element comprises a housing in which two control chambers are formed, which are isolated from each other and comprise a working port each as well as two pressure ports. Two of these ports are provided with a sealing seat each. The fluid control element further comprises a switching element movably mounted in said housing and comprising a sealing part in each control chamber. The sealing part cooperates with the sealing seats such that these are opened or closed. The fluid control element further comprises an actuating member for the switching element, the actuating member being able to bring the switching element into three positions.

Description:
BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 4,765,370 shows a fluid control element comprising a housing in which two control chambers are formed, which are each isolated from each other and comprise a working port each as well as two pressure ports, two of the ports being provided with a sealing seat each. The fluid control element further comprises a switching element movably mounted in the housing and comprising a sealing part in each control chamber, the sealing part cooperating with the sealing seats such that these are opened or closed, and still further comprises an actuating member for the switching element. This fluid control element represents a 4/2-way valve for actuating hydraulic actuator cylinders, for example. When actuating, for example, a double-acting hydraulic cylinder, the working port of the one control chamber is connected to a working port of the hydraulic cylinder and the working port of the other control chamber is connected to the other working chamber of the hydraulic cylinder. In a first position of the switching element, the resting position, the one working chamber of the hydraulic cylinder is pressurized so that a movement occurs in a first direction, whilst in an activated position of the switching element into which the switching element is moved by an electric magnet, the other working chamber of the hydraulic piston is pressurized so that a movement occurs in the opposite direction. 
     It is often required, however, in addition to a movement of the hydraulic piston in a first and a second direction that the hydraulic piston, for example, is maintained fixed in a position or is freely movable. For this purpose 4/3-way valves are needed as described with reference to FIG.  13 . Illustrated schematically in FIG. 13 is a hydraulic piston  1  disposed between two working chambers  2 ,  3 . The working chamber  2  is connected to a working port A of a 4/3-way control element illustrated schematically and identified by reference numeral  10 , and the working chamber  3  is connected to a working port B. Furthermore, two pressure ports P, R are provided, port P providing a pressurized fluid and port R forming a return flow conduit. 
     The control element shown as example 1 permits three operating conditions. In the left-hand switching position the hydraulic piston  1  is biased so as to move to the right. In the middle switching position the hydraulic piston  1  is blocked. In the left-hand switching position the hydraulic piston  1  is biased so as to move to the left. 
     The examples 2 and 3 likewise make possible three switching positions, the left-hand and the right-hand switching positions in each case corresponding to the right-hand and left-hand switching positions of the first example. The middle switching position in example 2 results in the hydraulic piston  1  being freely movable and the middle switching position of example 3 results in the hydraulic piston  1  being blocked by the pressure furnished by the pressure port P. 
     Hitherto, achieving such switching functions necessitated the use of piloted slide valves. 
     The object of the invention consists in providing a simple, direct-acting control element having a 4/3 operational mode to thus reduce the expense in terms of technical equipment in actuating a cylinder and to permit a more direct and faster operation of actuator cylinders and actuators, respectively. 
     BRIEF DESCRIPTION OF THE INVENTION 
     To achieve this object, a fluid control element is provided which comprises a housing in which two control chambers are formed, which are isolated from each other and comprise a working port each as well as two pressure ports. Two of these ports are provided with a sealing seat each. The fluid control element further comprises a switching element movably mounted in the housing and comprising a sealing part in each control chamber. The sealing part cooperates with the sealing seats such that these are opened or closed. The fluid control element further comprises an actuating member for the switching element, the actuating member being able to bring the switching element into three positions. In this way the desired three switching positions are achievable with a control element having two control chambers without additional slide valves being necessary. Such an actuating member with which the switching element is may be brought into three positions is, for example a solenoid drive having a polarized drive element, the permanent magnet of which in the non-energized condition of its solenoid holds the switching element in a middle position, which also represents the resting position, and in the energized condition shifts the switching element into the one or the other direction depending on the direction of current flow. 
     In accordance with one preferred embodiment of the invention it is provided for that the sealing seats of one control chamber are disposed opposite each other on the one and the other side of the control chamber and that the sealing part arranged in this control chamber is configured with two opposing tongues disposed between the sealing seats and configured so as to be elastically resilient, and in the resting position are spaced away from each other such that they may simultaneously close the two sealing seats. In this embodiment all ports in the middle or resting position are closed. By moving the switching element, starting from the resting position, into the one or the other direction the desired ports may be selectively opened. 
     As an alternative it may be provided for that the sealing seats of one control chamber are disposed opposite each other on the one and the other side of the control chamber and the sealing part arranged in this control chamber is in contact with either the one or the other sealing seat. In this embodiment one sealing seat of each control chamber is closed in the resting position. As soon as the switching element is actuated in any direction, one of the sealing parts is lifted from the corresponding sealing seat and pressed against the opposite sealing seat whilst the other sealing part remains in contact at the corresponding sealing seat with no change in the switching condition in this control chamber. Depending on how the various ports are put in circuit, a variety of different switching conditions results. 
     In this alternative the sealing parts arranged in the two control chambers extend in the same plane or in different planes. In the resting position one of the sealing parts is then in contact with the sealing seat disposed on one side of the corresponding control chamber whilst the other sealing part is in contact with the other sealing seat arranged at the other side of the other control chamber. When the sealing parts are arranged in the same plane, the actuating travel needed for making the changeover is achieved by differing the spacing of the sealing seats away from the plane of the sealing parts in the resting position, whereas when the sealing parts are arranged in different planes the necessary actuating travel is achieved by different spacings assumed by the sealing seat from the sealing parts being in the resting position. 
     In accordance with a further embodiment it may be provided for that the sealing seats of one control chamber are arranged mutually staggered on the one and on the other side of the control chamber, and that the sealing part arranged in this control chamber is configured with two tongues arranged side by side, each of which being assigned to one of the sealing seats and configured so as to be springy and elastic. The effect of this configuration is basically the same as that described above having the two tongues opposite each other, except that here a larger number of switching conditions is possible. If required, in one of the control chambers the configuration as described above including opposite sealing seats and opposite tongues may be provided, whilst in the other control chamber the configuration having staggered sealing seats and tongues lying side by side may be employed. 
     It is preferably provided for, however, that in both control chambers the sealing seats of one control chamber are arranged mutually staggered on the one and the other side of the corresponding control chamber, a maximum number of switching conditions being possible in this case. 
     In this embodiment it may be either provided for that the tongues of the sealing parts of the switching element arranged in the two control chambers extend in the same plane. Technically the same effect is achievable by providing the two tongues, arranged in one chamber, so as to be mutually staggered. In cooperation with a suitable arrangement of the sealing seats relative to the arrangement of the tongues in the resting position, a variety of conditions is possible, i.e. the sealing seats in the two control chambers either being arranged such that in the resting position the tongues of the sealing parts are in contact with all sealing seats in the two control chambers, or as an alternative the sealing seats in the two control chambers are arranged such that in the resting position the tongues of the sealing parts are in contact with all sealing seats of a sole control chamber and with no sealing seat of the other control chamber. Finally, it is possible that the sealing seats are arranged in the two control chambers such that in the resting position the tongues of the sealing parts are each in contact with one sealing seat in each control chamber. Depending on the configuration selected in each case a wealth of different switching conditions is achieved with which any desired mode of actuating an actuator, for example a hydraulic actuating cylinder, is achievable. 
     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 illustrated in the attached drawings in which 
     FIG. 1 is a schematic illustration of part of a housing of a control element in accordance with the invention, comprising the control chamber and the sealing part arranged therein, 
     FIG. 2 is a schematic section view of a control element in accordance with the invention; 
     FIG. 3 is a schematic cross-section through the two control chambers of a control element according to a first embodiment of the invention; 
     FIG. 4 is a broken view in perspective of a sealing part employed in the control element as shown in FIG. 3; 
     FIG. 5 is a schematic plan view of a switching element as may be used in a control element in accordance with a second embodiment of the invention; 
     FIG. 6 shows in a schematic cross-section through the control chamber a control element according to the second embodiment of the invention; 
     FIG. 7 is a view, corresponding to that as shown in FIG. 6, of a control element in accordance with one variant of the second embodiment of the invention; 
     FIG. 8 is a schematic cross-section through the control chamber of a control element in accordance with a third embodiment of the invention; 
     FIG. 9 is a schematic plan view of a switching element as may be used in a control element according to FIG. 8; 
     FIGS. 10 a ,  10   b ,  10   c ,  10   d , and  10   e  illustrate various designs of the control element in accordance with the third embodiment; 
     FIGS. 11 a ,  11   b ,  11   c ,  11   d , and  11   e  illustrate various designs of a variant of the third embodiment; 
     FIG. 12 is a schematic view of an actuating member as may be used with the control elements in accordance with the invention; and 
     FIG. 13 is a schematic illustration of an actuator including various control elements. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIGS. 1 and 2, the configuration of the control elements in accordance with the invention will now be described in general. The control element  10  comprises a housing  12  in which two control chambers  20 ,  30  are configured so as to lie side by side and isolated from each other (only one of the chambers can be seen in FIG.  1 ). Opening into each control chamber is a working port and two pressure ports, the working port being identified by A and B, respectively, and the pressure ports by P and R, respectively. Two of the ports in each control chamber  20  and  30 , respectively, 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 a 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 also FIG. 12) 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 middle 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. 12 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. 12 by the reference numeral  19 . 
     The basic configuration of the switching element  14  consisting of 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 incorporated herein by reference. 
     Referring now to FIGS. 3 and 4 there is illustrated a control element as will now be described in accordance with a first embodiment of the invention. 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. At the end freely protruding into the corresponding control chamber each sealing part  24 ,  34  is provided with two tongues  26 ,  28  and  36 ,  38 , respectively. The two tongues  26 ,  28  and  36 ,  38 , respectively, are configured so as to be elastically resilient and opposite each other. As evident from FIG. 4 one of the tongues may be configured by a crank of the corresponding sealing part whilst the opposite tongue is formed by an additional part cranked mirror inverted and connected to the sealing part, for example, by spot welding. Of course, provided around each of the tongues  26 ,  28  and  36 ,  38 , respectively, is the elastomer layer  13  known as such. 
     The sealing seats  21 ,  22  and  31 ,  32 , respectively, which are arranged in the control chambers  20 ,  30  are configured so as to lie opposite each other (see FIG.  3 ). Although this is not necessarily the case, the ports assigned to the sealing seats  21 ,  22  and  31 ,  32 , respectively, have the same middle axis, i.e. the corresponding sealing seats are disposed coaxially to each other. Opening into each control chamber on one side of the sealing seats is the remaining port. In the configuration as shown in FIG. 3 the ports are put in circuit such that the sealing seats are assigned to the two pressure ports P, R whilst the working port A and B, respectively, opens into the side. 
     The spacing of the two sealing seats  21 ,  22  and  31 ,  32  assigned to each other is selected such that in the resting position, i.e. with the actuator protuberance  15  not actuated, the two tongues  26 ,  28  and  36 ,  38 , respectively, close the corresponding sealing seats. This is evident from FIG.  3 . In this position all fluid ports are closed. When, starting from this position, the actuating protuberance is acted upon, the sealing parts  24 ,  34  are moved either upwards, resulting in the port R of the control chamber  20  and the port P of the control chamber  30  being connected to the working ports A, B, or downwards, resulting in the pressure ports R of the control chamber  20  and P of control chamber  30  being connected to the working ports A, B. It is in this way that a 4/3-way control element is produced. 
     By differently putting the various ports of the illustrated control element in circuit, other switching conditions are possible, as will readily be appreciated. 
     Referring now to FIGS. 5 and 6 there is described a second embodiment of the control element in accordance with the invention. The switching element  14  comprises two sealing parts  24 ,  34  arranged side by side and in the same plane (see more particularly FIG.  6 ). The sealing seats  21 ,  22  and  32 ,  32 , respectively, which are arranged in the control chambers  20 ,  30  protrude into the control chambers differingly far. As evident from FIG. 6 the sealing seat  21  arranged on the upper side of the control chamber  20  protrudes so far into the control chamber that it is in contact with the sealing part  24  located in the starting position. In a similar way the sealing seat  32  arranged on the underside of the control chamber  30  protrudes so far into the control chamber that it is in contact with the sealing part  24  located in the resting position. The sealing seat  22  arranged on the underside of the control chamber  20  as well as the sealing seat  32  arranged on the underside of the control chamber  30  are arranged spaced away from the sealing part  24  and  34 , respectively, located in the resting position. 
     Referring now to the resting position of the sealing parts  24 ,  34  as shown in FIG. 6 the switching element can be made to assume two positions. In a first position in which the two sealing parts  24 ,  34  are biased so as to move upwards there is no further change in the position of the sealing part  24  since it is already in contact with the sealing seat  21  and is elastically deformed, whereas the sealing part  34  is lifted from the sealing seat  32  and pressed against the sealing seat  31 . In this position the pressure port P is thus connected to the working port B of the control chamber  30  whilst as regards the control chamber  20  no change in the switching condition occurs. When, however, the sealing parts  24 ,  34  are biased so as to move downwards out of the resting position there is no change in the switching condition as regards the control chamber  30  whilst the sealing part  24  is lifted from the sealing seat  21  and pressed against the sealing seat  22 . Now, the pressure port identified P in this case is connected to the working port A of the control chamber  20 . 
     Referring now to FIG. 7 there is illustrated a variant of the second embodiment as shown in FIGS. 5 and 6. The difference in this case being that, now, the sealing seats  21 ,  31  arranged on the upper side of the control chambers  20 ,  30  as well as the sealing seats  22 ,  32  arranged on the underside of the chambers are each located at the same level. Furthermore the sealing parts  24 ,  34  are no longer arranged in the same plane, but mutually staggered. 
     The effect is similar to that as explained for the second embodiment. When starting from the resting position as shown in FIG. 7 the sealing parts  24 ,  34  are biased so as to move upwards there is no change in the switching condition as regards control chamber  20  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 biased so as to move downwards there is no change in the switching condition as regards control chamber  30  whilst the sealing part  24  of the control chamber  20  is lifted from the sealing seat  21  and pressed against the sealing seat  22 . 
     Both in the second embodiment as shown in FIGS. 5 and 6 and in the variant of the second embodiment as evident from FIG. 7, different switching conditions may be achieved by suitable swapping of putting the ports in circuit. 
     Referring now to FIGS. 8 and 9 t here is described a third embodiment of a control element in accordance with the invention. In this embodiment the sealing seats arranged in the control chambers  20 ,  30  are no longer configured coaxially opposite each other, but mutually staggered as evident from FIG.  8 . In this arrangement the sealing seats  21 ,  31  arranged on the upper side of the control chambers  20 ,  30  protrude into the control chambers up to the same level and also the sealing seats  22 ,  32  arranged on the underside of the control chambers  20 ,  30  are each located at the same level. 
     The sealing part of the switching element  14  protruding into the control chamber  20  and  30 , respectively, consists for each control chamber of two parallel tongues arranged side by side. Thus, two tongues  26 ,  28  protrude into the control chamber  20  and two tongues  36 ,  38  protrude into the control chamber  30 . All tongues  26 ,  28 ,  36 ,  38  extend in the same plane in the resting position. As evident from FIG. 8 the spacing of the level defined by the sealing seats  21 ,  31  from the level defined by the sealing seats  22 ,  32  is dimensioned such that all tongues are in contact with their assigned sealing seats in the resting position of the switching element  14 , closing them off. In the resting position as shown in FIG. 8 all ports are thus blocked. 
     When starting from the resting position as shown in FIG. 8 the tongues  26 ,  28 ,  36 ,  38  are biased so as to move upwards, there is no change in the condition as regards the tongues  26 ,  36  since these tongues react merely elastically and continue to remain in contact with the corresponding sealing seats, whereas the tongues  28 ,  38  are lifted from their assigned sealing seats  22 ,  32  and the working port A of chamber  20  is connected to the pressure port R, whilst the working port B of control chamber  30  is connected to the pressure port P. 
     Referring now to FIG. 10, in the illustrations  a ) to  e ) there are shown various control elements in accordance with a third embodiment each achieving a different switching condition by a change in the spacing of the sealing seats from the corresponding tongues in the resting position and by a different putting in circuit of the various ports. The resulting switching conditions are evident from the illustrations and the likewise indicated switching symbols so that there is no need to detail them. 
     Referring now to FIG. 11, in the illustrations  a ) to  e ) there are shown various control elements in accordance with a variant of the third embodiment on the basis of the gist as known from FIG. 7 showing that the tongues of the switching element are mutually staggered. In this arrangement and in conjunction with differingly putting the ports in circuit and with different spacings between the sealing seats and the tongues in the resting position, the same switching conditions are achievable as already shown in the illustrations  a ) to  e ) as evident from FIG.  10 .