Patent Publication Number: US-2023162901-A1

Title: Actuating device

Description:
Actuating devices typically having the form of so-called actuating solenoids are known in a plurality of different designs (DE 10 2004 051 332 A1). Such devices are regularly used to control fluid valves and are equipped in a known manner with a magnetic drive having an energizable solenoid coil. 
     During operation, the coil or the magnetic drive heats up, wherein the heat is dissipated to the environment as power loss and the performance of the actuating device is reduced because of the heat. If metallic materials are used for the actuating device, they regularly have very high thermal conductivity coefficients, to rapidly dissipate the heat generated into the environment, which contributes to reducing any power losses. In addition to the fact that the use of metallic materials and their shaping is cost-intensive, their use in the context of current-conducting and current-carrying components such as the power supply or the solenoid coil with its coil windings is not feasible owing to a lack of insulation. 
     Accordingly, increasingly the use of plastic materials has already been proposed in the prior art (DE 10 2014 008 612 B4) for actuating devices of the type mentioned, for the purpose of electrically insulating the current-carrying components and cost-effectively producing a necessary housing for the magnetic drive; however, the thermal conductivity is reduced by the use of the plastic materials mentioned, so that this design is not feasible in particular for magnetic drives having a lot of power and a small size at the same time. 
     Accordingly, the invention addresses the problem of providing a high-performance actuating device in the most cost-effective manner possible, even for small sizes. 
     An actuating device having the features of claim  1  solves this problem. 
     According to the characterizing part of claim  1 , provision is made for improved heat dissipation, parts of the device consist of at least one special plastic material having a thermal conductivity coefficient between 0.25 and 1.25 
     
       
         
           
             
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     The use of the special plastic material having the specified low thermal conductivity coefficient provides, on the one hand, electrical insulation for the current-carrying components of the magnetic drive and the solenoid coil and, on the other hand, a high heat dissipation rate similar to that of metallic materials to the environment, which counteracts undesirable heating caused by the heat generated remaining in the device during the latter&#39;s operation, improving performance in that way. 
     Particularly in the case of actuating devices or actuating solenoids, which have to apply high actuating or switching forces at a small size and/or are designed as fast-switching systems with a high number of load cycles, rapid heat dissipation of large amounts of heat to the environment plays a major role for their functionality. 
     It has been shown that the solenoid coil having the energizable coil winding is the main heat source during operation, so in an advantageous manner it is accommodated in an enclosure, which at least partially, but preferably completely, comprises the respective special plastic material. Practical tests using the solution according to the invention have shown that although the core of the solenoid coil still heats up intensely in operation, the resulting heat quantities are rapidly dissipated from the core of the solenoid coil via the respective special plastic material, leading to significantly improved performance results compared to the known solutions, which are predominantly constructed from metal materials and/or the usual plastic materials. 
    
    
     In a particularly preferred embodiment of the actuating device according to the invention, provision is made for the enclosure for the coil winding of the solenoid coil to consist of a winding receiving as its one part and a cover part closing the winding receiving as its further part, and that both parts are made up of the same special plastic material. In this way, starting from the inside of the solenoid coil and moving outwards, there is a layered decrease of the temperature having a uniform gradient, more or less on all sides of the winding receiving having the cover part, wherein it is further advantageous for the temperature decrease if the winding receiving and the cover part have largely the same wall thicknesses. 
     For improved heat dissipation, it has also proved advantageous that a perimeter sleeve of the magnetic drive adjoins to the winding receiving of the enclosure in the direction of the magnetic drive and an outer housing part of the device housing adjoins to the cover part of the enclosure in the direction of the surroundings, wherein a circumferential annular gap is accommodated between the inner wall of this outer housing part and the outer wall of the cover part. It is still within the scope of the invention in special applications for the actuating device to provide the annular gap with a cooling medium, which may originate from a cooling circuit. 
     Preferably, at its free, opposite ends the annular gap is then delimited by a pole plate and by the outer housing part, between which the winding receiving for the coil winding extends, arranged concentrically to the annular gap. Both the pole plate and the outer housing part are preferably made of a metallic material having a good thermal conductivity. For good heat dissipation, the preferred formation is also that the magnetic drive has a magnet armature that is guided in a longitudinally movable manner along a bearing point that is accommodated stationarily within the perimeter sleeve, which penetrates the pole plate together with the magnet armature at a passage point of the pole plate. By the bearing point for the magnet armature a cavity surrounding the magnet armature is formed between the armature and the perimeter sleeve, wherein said cavity is kept free of material and in that way supports the desired improved heat dissipation towards the inside. 
     A further component of the magnetic drive, a pole core, which is penetrated by an actuating element, which is guided along a further bearing point arranged stationarily in the pole core, contributes thereto. In this way, too, a cavity is created via the further bearing point between the actuating element, typically having the form of an actuating rod for the valve piston of a fluid valve to be connected, and the pole core, which facilitates heat dissipation from the coil system in the direction of its center. To achieve heat flows in the direction of the pole core, it is advantageous for the free end of the perimeter sleeve to open out at the level of the pole core, at which the one free end of the winding receiving for the coil winding abutting the outer housing part terminates. It is particularly advantageous if the pole plate, the pole core, the perimeter sleeve and the outer housing part consist of metal materials having a good thermal conductivity. In addition to stainless steel material for the outer sleeve, free-cutting steels (11SMn30) are suitable for the other components mentioned, as they are easy to process, in particular are formable it the desired shape. 
     In a preferred embodiment of the actuating device according to the invention, provision is made for the housing part to form a receiving cup, the bottom of which has a penetration space for the pole core to penetrate, and for the bottom of the housing part to be preferably thicker than the adjoining cylindrical housing shell of the housing part. This makes for a particularly simple assembly of the actuating device, in which the relevant components can be stacked from the free front face into the cup-like housing part, which forms a kind of mounting space in this way. 
     In a further, particularly preferred embodiment of the actuating device according to the invention, provision is made for at least the solenoid coil and subsequently the pole plate to be accommodated in the receiving cup of the housing part from the receiving cup&#39;s free end face, wherein said pole plate rests on a termination piece, which is held in the housing part at a predeterminable preload by means of a flared lap. In this way, the flared lap is used to keep the components accommodated in the housing part together using a predefinable contact pressure or preload to the specified extent, facilitating the heat transfer. 
     In a further preferred embodiment of the actuating device according to the invention, provision is made for the outer circumference of the enclosure of the solenoid coil to rest on the housing part, for the inner circumference of the enclosure to rest at least partially on the pole core and for the two opposite end faces of the enclosure to rest on the bottom of the housing part and on the pole plate, respectively. This also facilitates the heat transfer between the structural components mentioned above and achieves good heat dissipation, which also applies in the case where a pressure-resistant perimeter sleeve, which is preferably also equipped with good thermal conductivity, extends between internal parts of the enclosure and the adjacent opposite sections of the outer circumference of the pole core. 
     In a further preferred embodiment, the housing part forms the circumferentially closed housing shell, to the longitudinal axis of which at least the solenoid coil, the pole plate and the pole core are arranged concentrically in relation to each other. The concentric arrangement of essential components in the actuating device results in a space-saving construction in addition to a good heat transfer between the components. 
     In a further, particularly preferred embodiment of the actuating device according to the invention, provision is made for both the bottom of the housing part and the pole core to be in direct contact with the valve body, preferably flush with each other at their adjacent end faces, wherein said valve body is preferably formed from a material having a high thermal conductivity coefficient, such as aluminum. In this respect, owing to the flush direct contact, the block-like valve body forms a heat reservoir to dissipate the heat generated during operation of the actuating device directly into the heat body used as a heat reservoir. In this respect, the valve body is a component of the actuating device as a whole. 
     The special plastic material consists of preferably injection-moldable, polyamide 6 material, which is preferably reinforced with 10% glass fiber content and which is available on the market under the brand names Radiflam or Zytel. 
     Preferably, provision is made for the respective special plastic material to be flame-retardant, in particular to be provided with flame-retardant additives, such as magnesium hydroxide and/or carbon. Particularly in the case of high-temperature stresses, the actuating device can be equipped with a type of fire extinguisher that helps to prevent a coil fire in the event of failure. 
     Below, the actuating device according to the invention is explained in more detail based on an exemplary embodiment according to the drawing. Here, in principle and not to scale, the single FIGURE shows a longitudinal section through the actuating device with parts of a valve housing connected in the usual way, without the movable valve parts and without the fluid ports. 
     The single FIGURE shows an actuating device according to the invention having a magnetic drive  12  accommodated in a housing  10  of the device, wherein said magnetic drive  12  has a perimeter sleeve  14  forming a pole tube. The perimeter sleeve  14  is mainly cylindrical and is closed at one end to form a bottom  16 . A bearing point  18  is concentrically and stationarily accommodated within the perimeter sleeve  14 , wherein along said bearing point  18  a magnet armature  22  as part of the magnetic drive  12 , is guided in a longitudinally movable manner in the direction of the longitudinal axis  20  of the actuating device. 
     On its side  24  facing away from the bottom  16  of the perimeter sleeve  14 , an actuating element  26  aligned coaxially with the magnetic armature  22 , is secured to the magnetic armature  22 . The free end  28  of the actuating element  26  facing away from the magnet armature  22 , is used to actuate movable valve parts (not shown in the FIGURE) of a valve housing  30  to which the actuating device is connected. In this respect, the FIGURE only roughly shows the housing outlines. This valve structure is common and therefore not shown or described in any detail. 
     The magnetic drive  12  comprises a solenoid coil  34  having an energizable coil winding  36 , to move the magnet armature  22  within the perimeter sleeve  14 . The coil winding  36  is accommodated in an enclosure  38  having a winding receiving  40  and a cover part  42  closing the winding receiving  40 . The winding receiving  40  has a cylindrical bottom  44  and, at both ends of the bottom  44 , an annular disc-shaped wall  46 ,  48  extending perpendicularly radially outwardly from the bottom  44 , each. The two annular disc-shaped walls  46 ,  48 , which are aligned in parallel to each other, together with the bottom  44  of the winding receiving  40  form a kind of trough for accommodating the coil winding  36 . The cover part  42 , which is formed cylindrically, encompasses the winding receiving  40  and is connected to the free ends  50  of the annular walls  46 ,  48  such that the winding receiving  40  and the cover part  42  delimit a cylindrical space  52  for receiving the coil winding  36  of the solenoid  34 . The coil winding  36  contacts the inside of the winding receiving  40  and the inside of the cover part  42  essentially without forming a gap. 
     The winding receiving  40  encompasses essential parts of the magnetic drive  12 . The cup-shaped perimeter sleeve  14  forming the pole tube, of the magnetic drive  12 , adjoins to the winding receiving  40  of the enclosure  38  in the direction of the longitudinal axis  20  of the actuating device, i.e. radially inwards. 
     An outer housing part  54  of the device housing  10  adjoins to the cover part  42  of the enclosure  38  in the direction of the surroundings, wherein said device housing  10  encompasses the magnetic drive  12 , in particular the enclosure  38 . The outer housing part  54  has a cylindrical main housing part  56 . An annular disc-shaped projection  60  extends perpendicularly radially inwards away from the end  58  of the main body part  56  facing the valve body  30 . The free end  62  of the projection  60  as the bottom of a receiving cup formed in this way, in the radial direction mainly ends lined up with the side of the bottom  44 , facing the perimeter sleeve  14 , of the winding receiving  40 , wherein the annular wall  46  facing the valve body  30 , of said winding receiving  40  contacts the projection  60 . An annular disc-shaped pole plate  64 , which encompasses the perimeter sleeve  14 , adjoins the winding receiving  40  and the cover part  42  on the side facing away from the valve body  30 , of the annular wall  48  facing away from the valve body  30 , of the winding receiving  40 . 
     The device housing  10  further comprises a termination piece  66 , which is inserted into the cylindrical main housing part  56  from the side  68  facing away from the valve body  30 , of the main housing part  56  and is mounted in the main housing part  56  by means of a circumferential flared lap  70 . The termination piece  66  has a central through hole  72 . 
     The main housing part  56  is spaced apart from the cover part  42  of the enclosure  38  such that a circumferential annular gap  74  is formed between the inner wall of the main housing part  56  and the outer wall of the cover part  42 , wherein through said annular gap  74  a further cylindrical space is formed in the device housing  10 . The annular gap  74  is co-delimited at its free, opposite axial ends by the pole plate  64  and by the projection  60  of the outer housing part  54 , respectively. The winding receiving  40 , the cover part  42 , and the annular gap  74  extend between the pole plate  64  and the projection  60  of the outer housing part  54 , wherein the winding receiving  40  and the cover part  42  are disposed to be concentric with the annular gap  74 . 
     The bearing point  18  of the magnet armature  22  encompasses the magnet armature  22  starting from its central section in the direction of the end section  76  facing away from the valve body  30 , of the magnet armature  22  over a distance which, viewed in the longitudinal direction of the magnet armature  22 , equals approximately half the height of the magnet armature  22 . As a result, the end section  76  facing away from the valve body  30 , of the magnet armature circumference and the front face  78  facing away from the valve body  30 , of the magnet armature circumference are spaced apart from the perimeter sleeve  14  while forming a cavity  80 , and a section  82  facing towards the valve body  30 , of the magnet armature circumference is also spaced apart from the perimeter sleeve  14  while forming a further cavity  84 . 
     The perimeter sleeve  14 , the bearing point  18  and the magnet armature  22  pass through the pole plate  64  at a passage point  86  of the pole plate  64 . 
     Further provided as part of the magnetic drive  12  is a pole core  88  having a centrally extending bore  90  through which the actuating element  26  extends. At its outer circumference in its end section  92  facing the magnet armature  22 , the annular diameter  94  of the pole core  88  decreases, tapering in the direction of the magnet armature  22 . As stated above, the housing part  54  forms a kind of receiving cup, the bottom  60  of which has a penetration space for a central penetration of the pole core  88 , wherein the bottom  60  of the housing part  54  is preferably thicker than the adjoining cylindrical housing shell of the housing part  54 , to allow good heat dissipation via the bottom  60  in the direction of the block-like valve body  30 . 
     At least the solenoid coil  34  and then the pole plate  64  are received from the free end face of the receiving cup of the housing part  54 , wherein said pole plate  64  rests on a termination piece  66 , which is held in the housing part  54  at a predeterminable preload by a flared lap  70 . Furthermore, the outer circumference of the enclosure  38  of the solenoid coil  34  is supported by the housing part  54 , the inner circumference of the enclosure  38  of the solenoid coil  34  is supported by at least partially the pole core  88  and the two opposite end faces of the enclosure  38  are supported by the bottom  60  of the housing part  54  and on the pole plate  64 , respectively. The shell of the perimeter sleeve  14  extending between the enclosure  38  and the pole core  88 , does not prevent effective support. The housing part  54  forms a closed housing shell on the circumference, to the longitudinal axis of which at least the solenoid coil  34  together with the pole plate  64  and the pole core  88  are arranged concentrically in relation to one another. This results in a compact structure with good heat transfer between the components mentioned above. 
     As shown in particular in the FIGURE, the actuating device is provided with both the bottom  60  of the housing part  54  and the pole core  88  ending preferably flush with each other at their adjacent end faces in direct abutment with the valve body  30 , which is preferably formed of a material having a high thermal conductivity coefficient, such as aluminum. In particular, the valve body  30  is formed as a metal block forming a kind of heat accumulator in this respect. When viewed in the direction of the FIGURE, the lower side of the bottom  60  terminates with the lower side of the pole core  88  in a joint plane extending transverse to the longitudinal axis of the housing part  54 . 
     The maximum outer diameter of the magnet armature  22 , which has a diameter reduction at its end section  82  facing the valve body  30 , to form an annular step  98 , is dimensioned smaller than the minimum outer diameter of the pole core  88 . From the end face  100  facing the magnet armature  22 , of the pole core  88  a cylindrical recess  102  formed coaxially with the longitudinal axis  20  of the actuating device, is inserted into the pole core  88 , wherein on the annular side wall of said recess  102  the stepped end section  82  facing the pole core  88 , of the magnet armature circumference is guided at a reduced diameter. To this end, the magnet armature  22  and the pole core  88  are formed in such a way that, when the magnet armature  22  moves in the direction of the pole core  88 , the end face  106  facing the pole core  88 , of the magnet armature  22  comes into contact with the bottom of the cylindrical recess  102 , wherein at the same time the annular step  98  of the magnet armature  22  remains at a distance from the end face  100  facing the magnet armature  22 , of the pole core  88 . 
     The actuating element  26  is guided along a further bearing point  110 . The further bearing point  110  is concentrically and stationarily accommodated inside the drilled hole  90  of the pole core  88  and encompasses the actuating element  26  in its central section over a distance, which, viewed in the longitudinal direction of the actuating element  26 , equals approximately one quarter to one fifth of the length of the actuating element  26  between the front face  106  facing the valve body  30 , of the magnet armature  22  and the free end  28  of the actuating element  26 . As a result, the actuating element  26  is spaced apart from the pole core  88  outside of the further bearing point  110  to form two further cavities  112  in the device housing  10 . 
     The free end  114  of the perimeter sleeve  14  ends at the height of the side facing away from the valve body  30 , of the projection  60  of the outer housing part  54 , at which the winding receiving  40  for the coil winding  38  terminates with the outside of its annular wall  46  facing the valve body  30 . 
     In actuating devices known from the prior art, the magnetic drive, in particular the coil winding, heats up during operation when the coil winding is energized reducing the performance of the actuating device due to the heat. The heat is dissipated as power loss to the surroundings of the coil winding. According to Ohm&#39;s law, the thermal power dissipated by the coil winding as a power loss depends on the electric current flowing through the coil winding and on the resistance value of the coil winding, which in turn depends on the material, cross-section and length of the conductor of the coil winding. 
     If metallic materials are used for the actuating device, they regularly have very high thermal conductivity coefficients, to rapidly dissipate the heat generated into the environment of the actuating device contributing to reducing any power losses. In addition to the fact that the use of metallic materials and their shaping is cost-intensive, their use in the context of current-conducting and current-carrying components such as the power supply or the solenoid coil with its coil windings is not feasible owing to a lack of insulation. Electrically insulating components enclosing the coil winding, are therefore regularly made of plastic material having a rather poor thermal conductivity coefficient, which means that heat cannot be optimally dissipated from the coil winding. 
     According to the invention, therefore, for improved heat dissipation, parts of the actuating device are formed of at least one special plastic material having a thermal conductivity coefficient of 0.25 to 1.25 
     
       
         
           
             
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     Thus, the enclosure  38 , in which the coil winding  36  is accommodated, comprises at least partially the relevant special plastic material, namely the winding receiving  40  and/or the cover part  42  are made from a special plastic material, in particular either from the same or from different special plastic materials. 
     The respective special plastic material is made from, preferably injection-moldable, polyamide 6 material reinforced having a glass fiber content of 5% to 25%, preferably of 10%. In addition, the respective special plastic material is flame-retardant, in particular provided with flame-retardant additives. Such flame retardant additives are, for instance, magnesium hydroxide and/or carbon. 
     The cavities  80 ,  84 ,  112  contribute to improving the heat dissipation to the interior. 
     In addition, the pole plate  64 , the pole core  88 , the perimeter sleeve  14  and the outer housing part  54  are formed of metal materials having a good thermal conductivity, such as 11SMn30 or stainless steel 1.4301 and 1.4305. Also, the valve body  30  may be formed at least partially of metal, particularly preferably of aluminum, having a high thermal conductivity coefficient. The bearing points  18 ,  110  for the magnet armature  22  and the actuating rod  26  consist in particular of sintered bronze. 
     Such a design of the actuating device according to the invention, and in particular of the valve body  30 , makes for a particularly good dissipation of the heat of the actuating device to its environment.