Patent Publication Number: US-2011049405-A1

Title: Actuating device

Description:
The invention relates to an actuating device, in particular for actuating valves that can be connected externally, comprising a housing and a coil body arranged therein and having a coil winding, where said coil body encloses at least in part a pole tube to whose one free end a pole core is connected, with an armature which is guided to be longitudinally displaceable at least in the pole tube within an armature space, and which interacts with an actuating part for actuating the respective valve part, the pole tube being designed as a receiving sleeve for the armature, said receiving sleeve being fixed with its free end region at a fixed bearing point. 
     DE 10 2004 051 332 A1 discloses a generic actuating device. In the known solution, the pole tube on its one free end which projects out of the housing of the actuating device is provided with a flanged edge against which the armature can be supported in its one end-side travel position, the flanged edge leaving a center opening exposed into which a pressure equalization channel of the armature discharges which on its opposite side can be supported on the pole core in whose direction the pressure equalization channel discharges on its other side. On the opposite end, the pole tube has a flanged edge of less curvature which is directed in the opposite direction, and with which it is fixed in position between the coil body and the pole core both axially and also radially. As a result of the deflections toward the free edges of the pole tube, the latter is able to produce a certain longitudinal tolerance equalization in order to form a fitted mounting for parts of the actuating device. As a result of the defined clamping site of the pole tube between the pole core and the coil body, these tolerance equalization possibilities are limited. 
     To remedy this defect, DE 10 2005 061 184 A1 for a likewise generic actuating device has proposed forming the aforementioned flanged edge of the pole tube as a closed bottom part of a receiving sleeve which, supported by the pole core, is in contact with the latter, the bottom part of the pole tube being able to fit into the pole core such that it maintains its position, even if the armature for actuating a valve which can be connected to the actuating device moves back and forth and, in doing so, presses especially on the bottom part or is lifted off it by pulling itself. Since the flanged edge no longer borders an annular passage site, as shown above, but rather is closed, in this case, use for high pressures is also possible since in addition to pressure-tightness, a stiff, loadable pole tube system is formed. 
     The defined contact of the bottom part of the pole tube with the pole core achieves a type of fixing which enables tolerance equalization elsewhere on the pole tube in a widely drawn region. In this connection, it is provided that the pole tube on its free end discharges into a bead-shaped flange which is supported on the housing of the actuating device. The bead part of the flange is designed as a round bead; this makes it possible to position the free end region of the bead-shaped flange between the housing of the actuating device and housing parts of the adjoining valve body by clamping, and, as a result of the elastically resilient bead body, a type of articulation is implemented along which especially in the axial direction the pole tube with its installation length can be fitted within the coil body and the pole core. 
     On the basis of the prior art, the object of the invention is to further improve the known solutions while maintaining their advantages, specifically reliable, long-lasting actuating operation such that improved tolerance matching for a small installation size is achieved with little mechanical effort and therefore cost-efficiency. This object is achieved by an actuating device having the features of claim  1  in its entirety. 
     In that, as specified in the characterizing part of claim  1 , at the loose bearing point for the receiving sleeve which forms the pole tube a reset means acts on the latter and applies a force to the receiving sleeve which is directed away from the fixed bearing point, tolerance equalization can be enabled within a very widely drawn framework, and this amount of equalization can be stipulated by way of a suitable selection of the reset means. Regardless of the possible production tolerances of the individual components of the actuation device, the associated tolerance can thus be compensated, and, in this respect, individually equalized via the reset means acting on the receiving sleeve. 
     The actuating device can be set up as a modular kit, and, with the respective reset means as part of the kit, tolerance equalization can also be undertaken with installation lengths which are changed accordingly. If the reset means is made preferably from an energy storage device, especially preferably in the form of a disk spring, the indicated tolerance equalization can be undertaken even if the service and operating temperatures for the actuating device should vary within a wide range. 
     In one especially preferred embodiment of the actuating device according to the invention, the receiving sleeve located outside the housing has a bottom part which is widened relative to the outside diameter of the receiving sleeve and at the site of the change in diameter has a deflected edge on which the reset means acts. Preferably, the respective reset means with its one action side acts on the housing and with its other action side acts in the deflection region between the cylindrical outer periphery and projecting edge of the receiving sleeve. In this way reliable support of the reset means on the assignable housing parts is achieved, as is favorable delivery of force in the indicated deflection region. As a result of the closed bottom part configuration, the actuating device can also be used for high pressure applications. 
     In another preferred embodiment of the actuating device according to the invention, it is provided that the deflected edge of the receiving sleeve delimits a peripheral gap which is connected to the armature space to carry media, which space accommodates the armature, delimited by the tubular part of the receiving sleeve. The bottom part of the receiving sleeve as the pole tube can especially advantageously deflect and rebound due to the peripheral gap and in this way can counteract the impact motion of the armature on the bottom part by damping it. 
     If preferably the bottom part in its middle is provided with an offset which projects cup-like in the direction of the armature space, the bottom part is accordingly stiffened in terms of its strength and improved in its indicated damping behavior. Due to the cup-like projection which can engage the armature space, the actuating device is closed to the outside by the bottom part of the receiving sleeve in the axial direction, saving installation space. 
     In another preferred embodiment of the actuating device according to the invention, it is provided that the deflected edge has two leg sections which run parallel to one another with the formation of a peripheral gap with a uniform width; this enhances the application of force if the armature strikes the bottom part and relieves the deflected edge as a bending site. Since corrosive media may be located in the peripheral gap, the receiving sleeve is preferably made from a corrosion-resistant, high-grade steel material. It can consist of magnetizable or nonmagnetizable high-grade steel depending on the configuration of the actuating device. 
     In another especially preferred embodiment of the actuating device according to the invention, there is a fixed bearing point for the receiving sleeve on its free end edge, and the fixed bearing point, as illustrated, is caulked to the pole core for this purpose. The loose bearing point is located on the opposite end of the pole tube in the region of the closed bottom part, in particular at the site at which the pole tube emerges from the housing of the actuating device, and support is achieved by the coil body and/or the housing parts which are penetrated by the pole tube. Due to the action of the reset means on the loose bearing point, the receiving sleeve with its inner periphery is accordingly stretched and equalizes possible unevenness in the region of the travel path of the armature. The receiving sleeve is also kept permanently stressed in tension; this is beneficial for the case in which the armature strikes the bottom part of the receiving sleeve. The vibration pattern which may have been applied due to the pretensioned receiving sleeve can be avoided. 
    
    
     
       The embodiment according to the invention is detailed below using exemplary embodiments as shown in the drawings. The figures are schematic and not to scale. 
         FIG. 1  shows, as a longitudinal section, the actuating device as a whole, but without a connected valve device; 
         FIG. 2  shows an enlarged extract as shown in the circle D in  FIG. 1 ; 
         FIG. 3  shows, as a longitudinal section, part of the production form relating to the injection process of an actuating part onto the armature of the actuating device; 
         FIGS. 4   a ,  4   b , and  4   c  show, in a longitudinal section in a perspective top view and in a front view, a second embodiment of an injection solution which has been modified relative to  FIGS. 1 to 3 ; 
         FIGS. 5   a ,  5   b , and  5   c  show, in correspondence to  FIGS. 4   a ,  4   b , and  4   c , a third embodiment of an injection solution; 
         FIGS. 6   a ,  6   b , and  6   c  show, in correspondence to  FIGS. 4   a ,  4   b , and  4   c  a fourth embodiment of the injection solution; 
         FIG. 7  shows an enlarged extract as shown in circle A in  FIG. 1 ; 
         FIG. 8  shows an enlarged extract as shown in circle B in  FIG. 1 ; 
         FIG. 9  shows an enlarged extract as shown in circle C in  FIG. 1 ; 
         FIGS. 10 and 11  show, as a longitudinal section, the individual production steps for the detail solution as shown in circle C in  FIG. 9 . 
     
    
    
     The actuating device which is shown in a longitudinal section in  FIG. 1  and which is also referred to as an “actuating or switching magnet” in the technical jargon has a housing designated as a whole as  10  with a coil body  12  located therein with a coil winding  14 . This coil body  12  comprises at least in part a pole tube  16  which is essentially magnetically decoupled from a pole core  20  by means of a point of separation  18  in the form of a site which is left open. But the prior art also discloses solutions (not shown) in which a corresponding point of separation is formed by a weld or the like. Along the pole tube  16  an armature  22  is guided to be longitudinally displaceable in an armature space  24  which on its one free, front end interacts with a rod-like actuating part  26  for actuating fluid valves (not shown) of conventional design, especially in the form of pneumatic valves which are not detailed. To connect this valve, the pole core  20  on its free end is provided with a connecting flange  28 . The connecting flange  28  on its outer periphery has depressed ring grooves for at least partially accommodating the corresponding elastomer gaskets and for routing the media flows. 
     To energize the coil winding  14  of the coil body  12 , which preferably consists of at least one conductive copper wire, there is a plug part  30  which is preferably permanently connected to the remaining parts of the housing  10  by way of a sealing compound  32 . Viewed in the direction of looking at  FIG. 1 , on the left side and to the outside, an annular pole plate  34  ending with the sealing compound  32  is inserted and is caulked accordingly for securely holding it in the housing  10  to the latter (not shown). In addition, the pole plate  34  encompasses the outer periphery of the pole core  20 , which is held in the installation position shown in  FIG. 1  in the actuating device by way of the valve device which is not detailed. The pole tube  16  is designed cup-like as a receiving sleeve, and the bottom part  36  of the pole tube  16  forms a stop limit for the armature  22  in its travel position, which is on the extreme right viewed in the direction of looking at  FIG. 1 . The sealing compound  32  together with the coil body  12  consists of a plastic material such as, for example, polyamide, preferably PA6. The sealing compound  32  on the top side of the actuating device along its bottom side engages recesses of a cup-like housing jacket  38 , which is likewise a component of the housing  10 . Both the housing jacket  38  and the armature  22 , as well as the pole core  20  and the pole plate  34 , consist of a metallic material, and all these parts can consist of the same material. The pole tube  16  is preferably produced from a high-grade steel material which can be magnetically conductive or nonconductive depending on the application. 
     If the coil winding  14  and therefore the coil are energized by means of the plug part  30 , the armature  22  then is moved into its actuated position shown in  FIG. 1 , that is, viewed in the direction of looking at  FIG. 1  from a right position into the left position which corresponds to the actuating position as shown in  FIG. 1 . In this traveling motion, the armature  22  entrains the rod-shaped actuating part  26  whose free end, for an actuating process on the pneumatic valve, which is not detailed, in each of its travel positions projects out of the housing  10  and particularly out of the pole core  20 . In this traveling motion of the armature  22 , viewed in the direction of looking at  FIG. 1  to the left, an energy storage device in the form of a compression spring  40  is pretensioned, and as soon as the coil winding  14  is kept de-energized, the pretensioned compression spring  40  pushes the armature  22  back into its right initial position in which it can also make contact with the inside of the bottom part  36  of the pole tube  16 . In this de-energized state, the connected valve device is switched open, de-energized. In one modified embodiment (not shown) of the actuating device according to the invention, it could also be provided that the energy storage device in the form of the compression spring  40  be moved into the connected valve device in order to induce the indicated reset motion of the armature  22  together with the actuating part  26 . 
     But even when the current drops out, as a result of residual magnetism processes in the pole core  20  and in the pole plate  34 , it can happen that the armature  22  with its one free face remains adhering to the adjacent face of the pole core  20  facing it. To avoid this, between the two faces within the armature space  22  an anti-adhesion means  42  is inserted which encompasses the rod-like actuating part  26  with a radial distance in order to effectively execute decoupling. The rod-shaped actuating part  26  is penetrated by a center channel  44  which extends along the longitudinal axis  46  of the armature  22  and the actuating part  26 , which in this case also forms the optional axis of motion. The indicated middle channel  44  thus emerges into the exterior on the two opposite faces  48 ,  50  of the actuating part  26 . In particular, the center channel  44  on the right face  50  of the actuating part  26  leads into an open space  52  of the armature  22 , the open space  52  in turn leading into the armature space  24 , carrying pressure and medium. In the region between a sealing site  54 , which also forms a guide for the front end of the actuating rod  26  and the armature  22 , there is a cross channel  56  which with its one end discharges into the center channel  44  and with its other end emerges into a center space  58  which is encompassed by the pole core  20 . 
     The components including the center channel  44 , cross channel  56 , center space  58 , open space  52 , and armature space  24  form a type of pressure equalization system which is connected to a valve unit which is not detailed and compensates the pressure media originating from the valve unit such that the travel motion of the armature  22  together with the actuating part  26  is not adversely affected by possible pressure differences. Optionally, the pressure media guided in this way can also effectively support the actuating force to be applied by the armature  22  as a result of different area ratios. In the region of the point of separation  18 , the pole core  20  with a lug-like annular projection  60  overlaps the stepping  62  of the armature  22  offset in this region such that in each travel position of the armature  22  it is guided within the annular projection  60  so that the size of the point of separation  18  changes depending on the direction of travel of the armature  22 . 
     The rod-like actuating part  26  is formed from an injectable material which is injected onto, the armature  22 , especially as shown in  FIG. 3  in a connecting region  64 . When reference is made here to injection, this includes conventional injection, casting, and diecasting methods. The injectable material of the actuating part  26  can fundamentally be any material which can be processed in this way. But preferably, a plastic material is used, especially a thermoplastically processable plastic. The use of polybutylene terephthalate (PBT) has proven especially advantageous; it allows injection molding at mass temperatures from 230° C. to 270° C. The plastic material used has the necessary strength and stiffness, and the sliding and wear behavior has proven very good in practical tests for the application under consideration here. In this exemplary embodiment, the entire actuating part  26  is formed from an injectable plastic material; but here it is also possible to form the actuating part  26  in the front region from a conventional metal rod material, which is then injected only in the transition region to the armature  22  by means of injectable material. 
       FIG. 3  shows an injection mold which is designated as a whole as  66 , in part and in its fundamental structure. For the mold removal process this injection mold  66  is made in several parts (not shown) and can be assembled with its parts into the complete mold as shown in  FIG. 3 . The metal armature  22  is inserted into the injection mold  66  and on its free face forms the connection region  64 . The possible injection surface  68  formed in this way is delimited to the outside by the wall of the injection mold  66  and is chosen such that it at least does not project above the free face of the armature  22  in this region. Furthermore, within the injection surface  68  a peripheral, annular groove-like depression  70  is made in the free face of the armature  22 ; it is shown enlarged in  FIG. 2  and forms a type of undercut configuration  72  so that the injected plastic material can be held accordingly in the undercut in the armature  22  along the connecting region  64  by hooking underneath. Furthermore, the armature  22  has a centrally running center opening  74  which is penetrated by the actuating part  26 , as shown in  FIG. 3 , a correspondingly inserted mold core  76  enabling this configuration. Since the center opening  74  emerges into the widening open space  52 , another support surface is formed there as the second injection surface  78  of the armature  22 . In the region of the second injection surface  78 , the plastic material of the fastening part  26  overlaps the widening step formed here so that in the two directions of travel of the armature  22  secure anchoring of the actuating part  26  by way of the injection process is ensured. 
     The injection mold  66  as shown in  FIG. 3  is designed so that the rod-like actuating part  26  widens radially to the outside with the formation of the already described disk-like anti-adhesion means  42 . In this case, the pole core  20  is reliably decoupled from the armature  22 , and the anti-adhesion means  42  also forms a type of stop protection for the armature  22 . As  FIG. 2  in particular shows, between the disk-shaped anti-adhesion means  42  and the remaining enclosure front of the actuating part  26 , a stop step  80  is formed on which one free end of the energy storage device in the form of the compression spring  40  is supported. In this respect, the actual anti-adhesion means  42  is relieved of the force applied by the compression spring  40 , which otherwise in any travel position of the armature  22  presses the rod-like actuating part  26  in the direction of the connecting region  64  of the armature  22 . As furthermore follows from  FIGS. 1 and 3 , the center space  58  tapers to both sides by the rod-shaped actuating part  26  widening conically in diameter along two transition regions  82 . 
     The embodiment as shown in  FIG. 4  is at least modified such that in the connecting region  64  the injected plastic material has kidney-shaped widenings  84  to increase the linking mass, in turn the anti-adhesion means  42  being a one-piece component of the actuating part  26 . As a result of the diametrically opposite annular depression sites  86  which adjoin the kidneys  84  on both sides as circle segments, the energy storage device in the form of the compression spring  40  need not rest entirely on the injected plastic material, but for improved support can be directly supported on the metal regions of the armature  22 . 
     The embodiment as shown in  FIG. 5  corresponds in terms of its fundamental structure to the embodiment as shown in  FIG. 4 ; here, however, the anti-adhesion means  42  is securely connected on the face side as an anti-sticking washer via a corresponding engagement site  88  to the armature  22 . In this case, the compression spring  40  with its one end directly adjoins the face of the armature  22  in the region of the annular gap  90 , formed by the intermediate distance from the outer periphery of the fastening part  26  to the inner periphery of the anti-sticking washer of the anti-adhesion means  42 , which has been formed independently. 
     In the embodiment as shown in  FIG. 6 , in turn the anti-adhesion means  42  consists of an anti-sticking cup which with its radial enclosure edge adjoins the face of the armature  22  and otherwise engages the middle opening  74  of the armature  22  with its bottom part which is cylindrically arched inward. In this respect, the actuating part  26  with its injectable plastic material only in the region of the second injection surface  78  directly adjoins the armature  22 , and the first injection surface  68  is formed by the contact with the top side of the indicated anti-adhesion means  42 . 
       FIG. 7  shows the actuating device with the sealing site  54 , which seals the center space  58  to the outside relative to the free surrounding space into which the free end of the actuating part  26  projects. The indicated sealing site  54  is formed from a ring body  92  which is inserted into a shoulder-like widening  94  on the free end of the pole core  20 , specifically, is pressed in there. For this pressing process, the ring body  92  toward its two free ends has conical insertion aids  96 . The ring body  92  is formed from a material with good sealing and sliding properties; in addition to injectable plastics such as polyamide, nonferrous metal materials could also be used. To the extent good sliding properties are required, a PTFE material can also form the ring body  92 . So that the ring body  92  remains securely in the receiver in the pole core  20 , the pole core  20  can moreover be at least partially flanged along its free inner region so that the flange edge sections  98  to the outside form an effective stop boundary. The flange edge can also be made circumferential instead of the sectional configuration. 
     As  FIG. 7  further illustrates, an elastomer gasket  102  is inserted into an annular groove  100  and ensures sealing between the center space  58  and the free exterior. Moreover, between the annular groove  100  and the adjacent transition region  82  of the actuating part  26 , the diameter of the actuating part is widened and hence is in direct sliding contact with the inside of the ring body  92  which is preferably made as a compression sleeve; this yields additional sealing next to the elastomer gasket  102  and also ensures exact, end-side guidance for the actuating part  26  along the longitudinal or travel axis  46 . On the side to the transition region  82  facing away, conversely, the outside diameter of the actuating part  26  is reduced in order to ensure unobstructed operation and to avoid any adverse effect on the entry process of the actuating part  26  at the site of the transition to the ring body  92 . 
     As shown especially by  FIG. 8  in conjunction with  FIG. 1 , the pole tube  16 , which viewed in the direction of looking at the figures emerges on the right edge from the jacket  38  of the housing  10 , is provided with a widened and deflected edge  104  which extends with a definable axial distance to the outside wall of the housing jacket  38 . This configuration forms a type of loose bearing point. The edge  104  formed in this way forms the transition site between the cylindrical pole tube wall  106  and the bottom part  36  which runs transversely to it. Toward its middle, the bottom part  36  in the direction of the armature space  24  is provided with an offset  108  which projects in the right stop position of the armature  22  into its open space  52 . Otherwise, the elastically resilient bottom part  36  forms a stop cushioning for the striking armature  22  if it assumes its travel position on the extreme right as shown in  FIG. 1 . 
     The flanged edge  104  enhances this effect by forming an elastically resilient articulation. A peripheral gap  110 , into which medium can travel, leads into the edge  104  formed in this way; this in turn promotes stiffening of the entire system in this region. But it is especially advantageous that for the pole tube  16  in any temperature state, tolerance equalization is created by an elastically resilient reset means  112  in the form of an energy storage device, for example, formed from components of a disk spring  114 , of which  FIG. 8  shows one segment part. Instead of the individual segment disk springs  114  as shown in  FIG. 8 , essentially, however, there could be a disk spring assembly or other reset means, for example, in the form of a conventional helical spring which acts as a compression spring. A spring bellows or a pretensioned elastomer ring could also be used here if its use were possible at all based on the prevailing temperatures. 
     The reset means  112 , preferably in the form of a disk spring  114 , with its one end acts effectively on the free face of the housing jacket  38  and is supported with the other free end on a deflection region  116  at which the cylindrical pole tube wall  106  passes into the projecting edge  104 . With respect to a high degree of corrosion resistance, the pole tube  16  is formed from a high-grade steel material, and the reset means  112  used also has the advantage that when vibrations occur on the actuating device, the pole tube  16  is decoupled relative to the housing  10 . The projection selected to the right for the edge  104  relative to the free face of the housing jacket  38  is chosen such that the respective reset means  112  with its pretensioning can reliably act on the pole tube  16  and that the latter can be located on the remaining housing  10 , saving installation space. The indicated offset  108 , moreover, ensures that the pole tube  16  is reinforced in its pertinent bottom part region  36  so that residual deformations cannot occur in the event of striking of the armature  22 . 
     The solution, as shown in  FIGS. 9 to 11 , shows the left linking site of the pole tube  16  to the stationary pole core  20  as a fixed bearing point. For this purpose, the pole core  20  in the direction of its annular projection  60  has an annular groove-like constriction site  118  which passes into the remaining outside diameter of the pole tube  20  in the direction of the annular projection  60  in an arc-shaped transition region  120  (cf.  FIG. 1 ).  FIG. 10  shows that the step-shaped transition region  122  facing away from the arc-shaped transition region  120  is initially undeformed and here forms only an abutting region for the free end of the free end edge of the pole tube  16  which is flanged or caulked. When this production step is completed, as shown in  FIG. 11 , in a second production step the step-shaped transition region  122  is caulked to the inside along a caulk surface  124  which is offset in the direction of the pole plate  34  relative to the remaining outside diameter of the pole core  20 . In this way, the free end of the pole tube  16  is fixed not only axially and radially from both sides by the pole core material which is caulked in this region, but is also kept gas-tight, i.e., the solution shown here manages without an additional elastomer gasket or other sealing system between the pole core  20  in the region of its annular projection  60  and the fixing site on the free end edge of the pole tube  16 . 
     Since these actuating devices are also used to some extent in the high temperature range, and this fundamentally damages the elastomer material of seals, a cost-favorable sealing alternative is implemented here. Due to the arc-shaped transition region  120 , moreover, the pole tube is reliably guided without major kinks in the direction of the annular projection  60  on the outer periphery of the pole tube  22  so that unnecessary material stress for the thin-walled pole tube material does not occur. With respect to this guide distance  126  and the guide centering by way of the reset means  112  on the free end region of the pole tube  16 , it is ensured that bulging processes which could possibly limit the free mobility of the armature  22  with its actuating part  26  do not occur. 
     The actuating device according to the invention is intended especially in the low pressure range for use in pneumatic valves even in the high temperature range; with a corresponding modification, however, other applications are also conceivable, especially for hydraulic valves. The very lightweight actuating device has very short switching and reaction times; and extremely high load cycles, which can be in the range of multiples of millions, can be achieved.