Patent Application
20230162901
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
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'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'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'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
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2019 006 999.4 | Oct 2019 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/077996 | 10/6/2020 | WO |
