KONIAS, Stefan (Dorfmeisterstrasse 12, Erlangen, 91056, DE)
ROSS, Christoph (Küchelstrasse 12, Bamberg, 96047, DE)
HOPPE, Jens (Dorfmeisterstrasse 12, 91056 Erlangen, 91056, DE)
KONIAS, Stefan (Dorfmeisterstrasse 12, Erlangen, 91056, DE)
ROSS, Christoph (Küchelstrasse 12, Bamberg, 96047, DE)
Patent Claims
1. Electromagnetic actuation unit (2) of a hydraulic valve (1 ), with an armature (16) and a tappet pushrod (33), and - the armature (16) being arranged displaceably within the actuation unit (2), and a portion of the tappet pushrod (33) being arranged in a bore (23) running through the armature (16), characterized in that at least one groove (40) is formed on an outer surface area of the tappet pushrod (33), the outer surface area of the tappet pushrod (33) is adapted to the inner surface area of the bore (23), with the exception of the groove region, the groove (40) extending as far as the armature-side end of the tappet pushrod (33), and the axial extent of the said groove being designed to be greater than the depth of penetration of the tappet pushrod (33) in the armature (40).
2. Electromagnetic actuation unit (2) according to Claim 1 , characterized in that the tappet pushrod (33) is connected firmly to the armature (16).
3. Electromagnetic actuation unit (2) according to Claim 1 , characterized in that the groove (40) extends along the entire length of the tappet pushrod (33).
4. Electromagnetic actuation unit (2) according to Claim 1 , characterized in that, furthermore, a bearing element (37) is provided, which has a bearing face (39), the tappet pushrod (33) passing through the bearing element (37), and an outer surface area of the tappet pushrod (33) and the bearing face (39) forming a bearing point of the armature/tappet pushrod system (16, 33).
5. Electromagnetic actuation unit (2) of a hydraulic directional valve (1 ), with an armature (16) and a tappet pushrod (33), the armature (16) being arranged displaceably within the actuation unit
(2), - and the tappet pushrod (33) being connected firmly to the armature (16), characterized in that, furthermore, a bearing element (37) is provided, which has a bearing face (39), the tappet pushrod (33) passing through the bearing element (37), and - an outer face of the tappet pushrod (33) and the bearing face (39) forming a bearing point of the armature/tappet pushrod system (16, 33).
6. Electromagnetic actuation unit (2) according to Claim 5, characterized in that a portion of the tappet pushrod (33) is arranged in a bore (23) of the armature (16).
7. Electromagnetic actuation unit (2) according to Claim 5, characterized in that at least one groove (40) running axially is formed, at least in the region of the bearing point, on an outer surface area of the tappet push- rod (33).
8. Electromagnetic actuation unit (2) according to either one of Claims 4 and 7, characterized in that the outer surface area of the tappet push rod (33) is adapted, at least in the region of the bearing point, to the bea- ring face (39), with the exception of the groove region.
9. Electromagnetic actuation unit (2) according to either one of Claims 1 and 5, characterized in that the tappet pushrod (33) is designed as a component produced in a non-cutting manner.
10. Electromagnetic actuation unit (2) according to Claim 10, characterized in that the tappet pushrod (33) is produced by means of a drawing or extrusion method. |
Designation of the invention
Electromagnetic actuation unit
Description
Field of the invention
The invention relates to electromagnetic actuation units of a hydraulic valve according to the precharacterizing clauses of either one of Claims 1 or 5.
Hydraulic valves of this type, for example proportional directional valves, are used in internal combustion engines, for example, for the activation of hydraulic camshaft adjusters or of switchable cam followers. The hydraulic valves consist of an electromagnetic actuation unit and of a valve portion. The valve portion constitutes the hydraulic portion of the directional valve, this having formed on it at least one inflow connection, at least one working connection and a tank connection. By means of the electromagnetic actuation unit, specific connections of the valve portion can be hydraulically connected to one another in a directed manner and therefore the pressure-medium streams guided.
A hydraulic valve of this type is disclosed, for example in DE 199 34 846 A1. The hydraulic valve has a valve portion and an electromagnetic actuation unit.
The electromagnetic actuation unit of this hydraulic valve comprises, within a housing, a first magnet yoke, a coil arranged on a coil former, a second magnet yoke (pole core), an armature and a tappet pushrod (armature tappet). The coil and the first and the second magnet yoke are arranged coaxially to one another within the housing of the electromagnetic actuation unit. The first and the se- cond magnet yoke are in this case offset with respect to one another in the axial direction. The armature is located in the region between the first and the second magnet yoke radially within the first magnet yoke and is surrounded in the radial direction by the coil. The armature, the housing and the first and the second
magnet yoke form a flux path for the magnetic flux lines which are caused by the application of current to the coil.
The valve portion consists of a valve housing and of a control piston arranged axially displaceably in the latter. The valve housing is arranged within a reception orifice of the second magnet yoke and is connected at a fixed location to the latter. Three pressure-medium connections are formed on the outer surface area of the valve housing. A control piston is arranged axially displaceably inside the valve housing, the outside diameter of the control piston being adapted to the inside diameter of the valve housing. Furthermore, on the control piston, control portions are formed, by means of which adjacent pressure-medium connections can selectively be connected to one another or separated from one another as a function of the relative position of the control piston with respect to the valve housing.
By current being applied to the coil, the armature is urged in the direction of the second magnet yoke, this movement being transmitted by means of a tappet pushrod mounted on the armature to the control piston. The latter is then moved in the axial direction into a defined position counter to a spring supported on the valve housing, and the pressure-medium streams within the valve portion are thus controlled.
The tappet pushrod is produced in tubular form from a plane thin metal sheet as a bent stamping or as a deep-drawn part, is arranged within an armature bore and is connected fixedly to the armature. The tappet pushrod passes, so as to form a radial gap, through an axial bore passing centrally through the second magnet yoke and bears against the control piston of the valve portion. Oil can be exchanged via an axial bore of the tappet pushrod and the central bore of the armature between the subspaces lying on both sides of the magnet armature.
This embodiment has the disadvantage that the mounting of the armature/tappet pushrod system takes place solely via the outer surface area of the
armature. The least possible tiltings of the armature due to manufacturing tolerances may lead to the jamming of the tappet pushrod on account of the length of the system.
Furthermore, the production of the tubular tappet pushrod is relatively complica- ted.
Further problems may arise when the tappet pushrod is being pressed into the central bore of the armature. Owing to the small wall thickness of the sheet metal material of the tappet pushrod, distortions of the tappet pushrod may occur under the action of force, with the result that the non-positive connection bet- ween the armature and tappet pushrod may be weakened and a jamming of the tappet pushrod in the second magnet yoke cannot be ruled out.
Summary of the invention
The object on which the invention is based is, therefore, to avoid these disadvantages outlined and therefore to provide an electromagnetic actuation unit of a hydraulic valve, in which lubricant can be exchanged between the subspaces lying on both sides of the armature and the pressure difference occurring during the movement of the armature can be compensated. In this case, the production costs are not to be adversely influenced, and assembly is to be facilitated and have greater process reliability. A further object is to be seen in improving the mounting of the armature/tappet pushrod system and in avoiding a tilting and therefore the risk of jamming of the system.
In an electromagnetic actuation unit of a hydraulic valve, with an armature and with a tappet pushrod, the armature being arranged displaceably within the ac- tuation unit, and a portion of the tappet pushrod being arranged in a bore running through the armature, the object is achieved, according to the invention, in that at least one groove is formed on an outer surface area of the tappet push- rod, the groove extending as far as the armature-side end of the tappet push-
rod, and the axial extent of the said groove being designed to be greater than the depth of penetration of the tappet pushrod in the armature.
Electromagnetic actuation units of a hydraulic valve serve for generating an actuating movement and for transmitting this to a component of the valve portion belonging to the hydraulic valve. For this purpose, a displaceable armature is located within a magnetic circuit which inter alia contains a coil. By current being applied to the coil, the armature can be displaced within an armature guide sleeve, by means of which the armature is mounted. The movement of the armature is transmitted to an actuating member of the valve portion via a tappet pushrod which is connected fixedly to the armature. The armature is designed with a bore, normally a central bore. The tappet pushrod is usually inserted into the central bore of the armature and connected non-positively to the armature. Alternatively, positive or materially integral connections may also be considered. The armature separates from one another two subspaces lying in the directions of movement of the armature. During a movement of the armature, a pressure difference between the subspaces arises, which has an adverse effect on the performance of the hydraulic valve in terms of response behaviour, force to be applied and hysteresis. The same applies to lubricant which is located in the subspaces. In order to counteract these adverse effects, the central bore is designed to be open towards both subspaces. The tappet pushrod is provided with at least a groove which extends in the axial direction. In this case, the groove may assume any desired shape, for example a spiral groove or a groove running purely in the axial direction. The groove is open at the armature-side end of the tappet pushrod, that is to say the said groove communicates with that part of the central bore of the armature which extends beyond the tappet pushrod and consequently with the first subspace which lies on that side of the armature which faces away from the tappet pushrod. Furthermore, the groove extends in the axial direction over a length which is designed to be at least slightly greater than the depth of penetration of the tappet pushrod in the armature, that is to say the said groove likewise communicates with the subspace through which the tappet pushrod pas-
ses. Thus, at any time, the pressure between the two subspaces can be compensated and lubricant be introduced between the subspaces. By the tappet pushrod being designed as a solid component, its non-positive mounting in the armature can be carried out with high process reliability. A distortion of the tappet pushrod or an inadequate non-positive connection can be prevented.
Furthermore, there may be provision for the tappet pushrod to be connected firmly to the armature. In an advantageous development of the invention, there is provision, furthermore, for a bearing element to be provided, which has a bearing face, the tappet pushrod passing through the bearing element, and an outer surface area of the tappet pushrod and the bearing face forming a bearing point of the armature/tappet pushrod system. As a result, in addition to the first bearing point of the armature/tappet pushrod system, a second bearing point spaced apart from the first bearing point is introduced. On account of this and because of the solid design of the tappet pushrod, the mounting becomes more robust and therefore a jamming of the system is prevented.
Furthermore, there may be provision for the groove to extend along the entire length of the tappet pushrod. Since the tappet pushrod engages into the valve portion of the hydraulic valve, in this exemplary embodiment the groove also communicates with the valve portion. Pressure medium present in the valve portion, as a rule engine oil, can then be led via the groove to the armature and the bearing point of the tappet, with the result that these plain bearing points are supplied sufficiently with lubricant.
In a further embodiment of an electromagnetic actuation unit of a hydraulic directional valve with an armature and with a tappet pushrod, the armature being arranged displaceably within the actuation unit, and the tappet pushrod being connected firmly to the armature, the object is achieved, according to the inven- tion, in that, furthermore, a bearing element is provided, which has a bearing face, the tappet pushrod passing through the bearing element, and an outer face of the tappet pushrod and the bearing face forming a bearing point of the armature/tappet pushrod system. As a result, in addition to the first bearing
point of the armature/tappet pushrod system, a second bearing point spaced apart from the first bearing point is introduced between armature and armature guide sleeve. On account of this and because of the solid design of the tappet pushrod, the mounting becomes more robust and therefore a jamming of the system is prevented.
In this case, there may be provision for a portion of the tappet pushrod to be arranged in a bore of the armature and to be connected fixedly to the latter. Furthermore, there may be provision for at least one groove running axially to be formed, at least in the region of the bearing point, on an outer surface area of the tappet pushrod.
If a mounting of the tappet pushrod provided with at least one groove is provided in a bearing element, then, advantageously, the outer surface area of the tappet pushrod can be adapted, at least in the region of the bearing point, to the bearing face, with the exception of the groove region.
In both embodiments of an electromagnetic actuation unit, there may be provision for the tappet pushrod to be designed as a component produced in a non- cutting manner. In this case, the tappet pushrod is preferably produced by means of a drawing or extrusion method. These production methods constitute a cost-effective possibility for producing the tappet pushrod component in large quantities at low outlay in terms of time and of labour.
Brief description of the drawings
Further features of the invention may be gathered from the following description and from the drawings which illustrate an exemplary embodiment of the inventi- on in simplified form and in which:
Figure 1 shows an embodiment of an electromagnetic actuation unit according to the invention of a hydraulic valve by the example of a 4/3- way proportional valve,
Figure 2 shows the detail A from Figure 1 ,
Figure 3 shows the detail B from Figure 1 ,
Figure 4a shows a perspective illustration of the armature/tappet pushrod system,
Figure 4b shows a longitudinal section through the armature/tappet pushrod system,
Figure 5 shows the detail C from Figure 1.
Detailed description of the drawing
Figure 1 shows an embodiment of an electromagnetic actuation unit 2 according to the invention by the example of a hydraulic valve 1 designed as a 4/3- way proportional valve. Applications of the actuation unit 2 according to the invention in other hydraulic valves, such as 3/2-way proportional valves or switching valves, may likewise be envisaged.
The hydraulic valve 1 has an electromagnetic actuation unit 2 and a valve portion 3.
The electromagnetic actuation unit 2 has a coil former 4. The coil former 4 is composed of a coil carrier 4a, of a closing body 4b and of a connecting element 4c.
The coil carrier 4a carries a coil 7 consisting of a plurality of turns of a suitable wire. The radially outer surface area of the coil 7 is surrounded by a sleeve- shaped material layer 8 which consists of a non-magnetizable material. The material layer 8 may consist, for example, of a suitable plastic and may be injec- tion-moulded onto the wound coil 7.
An electrical plug connection 9, via which the coil 7 can be acted upon by current, is received within the connecting element 4c.
The coil former 4 is arranged at least partially within a housing 14 of pot-shaped design. In the embodiment illustrated, the coil carrier 4a and a part-region of the closing body 4b are located within the housing 14. The housing 14 has a bottom 20, opposite which an introduction orifice 14a lies in the axial direction. Furthermore, starting from the introduction orifice 14a the housing 14 has a first axial region 14b of smaller wall thickness, which merges in the axial direction via an introduction chamfer 14c into a second region 14d of larger wall thickness. In this case, the inside diameter of the housing 14 is designed to be larger in the first region 14b than the inside diameter of the second region 14d. During assembly, the coil former 4 can be introduced into the housing 14 via the introduction orifice 14a. In this embodiment, the closing body 4b is assigned the task of protecting the interior of the actuation unit 2 against the penetration of aggressive media via the introduction orifice 14a. For this purpose the outside diameter of the closing body 4b is adapted essentially to the inside diameter of the second region 14d of the housing 14. In addition an annular groove 5, in which a sealing element 6 is arranged, is formed on an outer surface area of the closing body 4b. The sealing element 6 may be designed, for example, as a sealing ring consisting of an elastomer. The sealing element 6 bears, on the one hand, against the boundary faces of the annular groove 5 and, on the other hand, against the inner surface area of the second region 14d of the housing 14 (Figure 2). A sealing point between the closing body 4b and the housing 14 is thereby implemented, with the result that the penetration of aggressive media into the interior of the actuation unit 2 at this point is effectively prevented.
During the mounting of the coil former 4 in the housing 14, the sealing element 6 is first inserted into the annular groove 5. The coil former 4 is subsequently introduced into the housing 14 via the introduction orifice 14a. This operation is appreciably simplified by the first region 14b of the housing 14 being designed with a larger outside diameter. First, the sealing ring 6 penetrates into the first region 14b of larger inside diameter. The inside diameter of this region 14b is designed to be larger than the outside diameter of the sealing element 6. This prevents the sealing element 6 from coming to bear along its entire circumference against the inner wall of the first region 14b and therefore prevents a force directed counter to the introduction movement from being exerted on the sealing element. In the region of the introduction chamfer 14c, the sealing element 6 comes to bear on its entire circumference against the housing 14, with the result that this circumference is deformed plastically. By the introduction chamfer 14c being formed between the first and the second region 14b, d of the housing 14, damage to the sealing element 6 during the transfer from the first to the second region 14b,d is effectively prevented. If the inside diameter of the first region 14b of the housing 14 is designed to be smaller than the outside diameter of the closing body 4b, increased by the amount of the radial thickness d of the material of the sealing element 6 in the expanded state, an egress of the sealing element 6 out of the annular groove 5 and, consequently, shearing- off are effectively prevented.
At the introduction orifice of the housing 14, tabs 15 are formed which first extend in the axial direction and which project beyond a step of the closing body 4b in the axial direction and surround it at least partially in the radial direction. The coil former 4 is thus fixed firmly within the housing 14.
The housing 14 may be manufactured, for example, by means of a cost- effective non-cutting forming process, for example a deep-drawing method, from a suitable blank, for example a suitable sheet metal part.
The coil former 4 is designed with an essentially cylindrical blind-hole-like recess 10 which is formed concentrically to the coil 7. Furthermore, the coil former
4 receives, at the bottom end of the recess 10, a first magnet yoke 1 1 of sleeve- shaped design. Within the recess 10 is arranged a pot-shaped armature guide sleeve 12 which defines an armature space. The bottom end of the armature guide sleeve 12 is provided with stops 13 extending axially inwards. Furthermo- re, the armature guide sleeve 12 extends along the entire recess 10 in the axial direction and at least partially surrounds the coil former 4 at its orifice in the radial direction.
An armature 16 is arranged displaceably in the axial direction within the armatu- re guide sleeve 12. The outside diameter of the armature 16 is adapted to the inside diameter of the armature guide sleeve 12, thereby implementing a mounting of the armature 16 in the armature guide sleeve 12. The displacement travel of the armature 16 is limited in one direction by the stops 13 and in the other direction by a second magnet yoke 17. The armature 16 separates the armature space defined by the armature guide sleeve 12 into a first and a second subspace 35, 36. The first subspace 35 extends between the bottom of the armature guide sleeve 12 and the armature 16. The second subspace 36 extends between the second magnet yoke 17 and the armature 16. The armature 16 has a bore 23 which runs in the axial direction and via which the two subspaces 35, 36 separated by the armature 16 communicate with one another. In the embodiment illustrated, this bore 23 is designed as centric bore which runs along the longitudinal axis of the armature 16.
The second magnet yoke 17 has a tubular portion 18 and an annular portion 19 adjoining the latter in the axial direction. The tubular portion 18 extends through an orifice 21 , formed in the bottom 20 of the housing 14, into the armature guide sleeve 12. In this case, the outside diameter of the tubular portion 18 is adapted to the diameter of the orifice 21 , with the exception of play which may possibly be present.
The housing 14 is supported on the annular portion 19 via a mounting flange 22. The mounting flange 22 serves for fastening the hydraulic valve 1 to a surrounding structure, not illustrated, for example a cylinder-head cover.
Figure 3 illustrates the connection point between the housing 14 and the second magnet yoke 17. This is a caulking 25. This may be implemented, for example, in that, after the positioning of the mounting flange 22 and of the housing 14 on the second magnet yoke 17, material is displaced from the outer circumferential face of the second magnet yoke 17 in the axial direction towards the housing 14 and is introduced, form-filling, into the connection point between these components. In this case, material accumulations are formed on the tubular portion 18 in the region of the connection point and extend outwards in the radial direction beyond an edge 24 of the orifice 21. In addition to a positive connection between the housing 14 and the second magnet yoke 17, non-positive connections are made at the same time between these components and the mounting flange 22 arranged between them. Furthermore, the housing 14 and the mounting flange 22 are centred with respect to the second magnet yoke 17 by means of this connection method. During the caulking operation, material of the second magnet yoke 17 is forced into the interspace between these components and the play is thus eliminated. Between the tubular portion 18 of the second magnet yoke 17 and the armature guide sleeve 12 is arranged a sealing ring 26. This prevents lubricant in the armature guide sleeve 12 from reaching the coil former 4, thereby protecting the latter against damage caused by the lubricant.
As can be seen in Figure 1 , the valve portion 3 of the hydraulic valve 1 designed as a 4/3-way proportional valve consists of a valve housing 27 and of a control piston 28. In this embodiment, the valve housing 27 is formed in one piece with the second magnet yoke 17. However, embodiments in which the valve housing 27 is formed as a separate component and is connected at a fixed location to the second magnet yoke 17 may also be envisaged.
A plurality of pressure-medium connections A, B, P are formed on the outer surface area of the valve housing 27 and communicate via clearances 30 with the interior of the valve housing 27 of essentially hollow-cylindrical design. In addition, the orifice, facing away from the electromagnetic actuation unit 2, of
the valve housing 27 serves as an outflow connection T. The middle pressure- medium connection P, which serves as an inflow connection, communicates via a pressure-medium line, not illustrated, with a pressure-medium pump, likewise not illustrated. The two outer pressure-medium connections A, B serve as wor- king connections. The outflow connection T communicates with a pressure- medium reservoir, likewise not illustrated.
A control piston 28 is arranged axially displaceably within the valve housing 27. Control portions 31 in the form of annular webs are formed on the outer surface area of the control piston 28. The outside diameter of the control portions 31 is adapted to the inside diameter of the valve housing 27. By a suitable axial positioning of the control piston 28 in relation to the valve housing 27, adjacent pressure-medium connections A, B, P can be connected to one another. The working connection A, B in each case not connected to the inflow connection P is at the same time connected to the tank connection T.
In this embodiment, the valve housing/second magnet yoke component 27, 17 consists of a suitable magnetizable steel. The component can thus fulfil all the required functions, such as the guidance of the control piston 28, and influen- cing of the magnetic field as part of the magnetic circuit and as a tie-up member between the hydraulic and the magnetic part of the hydraulic valve 1.
The control piston 28 is acted upon at one end by the force of a spring element 32 in the direction of the electromagnetic actuation unit 2. A tappet pushrod 33 bears against the other axial end of the control piston 28 and extends through a sliding sleeve (bearing element) 37 arranged in a bore of the second magnet yoke 17 (Figure 5). That end of the tappet pushrod 33 which faces away from the control piston 28 engages into the bore 23 of the armature 16 and is connected firmly to the latter (Figure 4a). The connection between the armature 16 and tappet pushrod 33 may, for example, be of a positive, non-positive or materially integral type. A movement of the armature 16 is therefore transmitted directly to the tappet pushrod 33 and consequently to the control piston 28. The
sliding sleeve 37 may be produced, for example, by means of a non-cutting forming method from a sheet metal blank of a non-magnetizable material. In the embodiment illustrated, the armature-side end of the sliding sleeve 37 is provided with an annular rim 38 running in the radial direction (Figure 5). The rim 38 serves, on the one hand, as a mounting stop which co-operates with the armature-side end of the second magnet yoke 17. Furthermore, the said rim defines a minimum distance which the armature 16 can assume in relation to the second magnet yoke 17, thus preventing direct contact between these components. A bearing face 39 is formed at the end of the sliding sleeve 37 which faces away from the armature 16. The bearing face 39 is adapted in this region essentially to the outer surface area of the tappet pushrod 33. The bearing face 39 and the outer surface area of the tappet pushrod 33 form an additional bearing point, via which the armature/tappet pushrod system 16, 33 is additionally mounted.
In addition, the outer surface area of the tappet pushrod 33 is adapted, at least in the region of its engagement into the bore 23 of the armature 16, essentially to the inner surface area of the bore 23. Contrary to this in the exemplary embodiment illustrated, two grooves 40 run- ning axially are introduced (Figures 4a, b) into the outer surface area of the tappet pushrod 33 and extend along the entire length of the tappet pushrod 33. Embodiments with only one, three or more than three grooves 40 may also be envisaged. By means of the grooves 40, lubricant can pass from the valve portion 3 via the bearing point on the sliding sleeve 37 into the armature space. At the same time, the grooves 40 communicate with the bore 23, with the result that lubricant can be transported to and fro between the two subspaces 35, 36. In addition, in this way, pressure compensation between the subspaces 35, 36 can take place when the armature 16 moves axially.
Since the outer surface area of the tappet pushrod 33 is adapted to the bearing face 39 of the plain bearing in the region of the bearing point, with the exception of the grooves 40, a relatively large area is available for mounting the tappet pushrod 33. Damage to the bearing face 39 during operation is thereby avoi-
ded. At the same time, a robust mounting of the armature/tappet pushrod system 16, 33 is made possible over the large bearing face 39, and a constant inflow of lubricant to the bearing point is ensured via the grooves 40. Since, furthermore, the outer surface area of the tappet pushrod 33 which pro- jects into the bore 23 is adapted to the inner surface area of the bore 23, with the exception of the grooves 40, on account of the relatively large overlap area a robust non-positive connection can be made cost-effectively by the tappet pushrod 33 being pressed into the armature 16. Pressure compensation between the two subspaces 35, 36 is at the same time made possible via the groo- ves 40 and the continuous bore 23.
This embodiment constitutes a cost-effective and simple-to-produce solution for mounting the armature/tappet pushrod system 16, 33 at the same time with the routing of lubricant into and within the actuation unit 2. Owing to the simultane- ous mounting of the armature/tappet pushrod system 16, 33 via the armature guide sleeve 12 and the sliding sleeve 37, two bearing points spaced apart from one another are available. As a result, the mounting becomes more robust and a tilting of the armature/tappet pushrod system is avoided.
In the embodiment illustrated, the tappet pushrod 33 is a solid component, with the result that the robustness of the actuation unit 2 is markedly increased. The tappet pushrod 33 may be produced cost-effectively by means of a non-cutting forming method from a suitable blank. Suitable production methods are, for e- xample, extrusion or drawing methods, in which a suitable blank, for example a wire of suitable thickness is pressed or drawn through a die, the die defining the final outer shape of the tappet pushrod 33.
The design according to the invention of an electromagnetic actuation unit 2 may, of course, also be employed in hydraulic valves 1 , in which the valve por- tion 3 is not connected firmly to the actuation unit 2, but, instead, is arranged without a firm connection in the axial direction with respect to the actuation unit 2. Hydraulic valves 1 of this type are used, for example, as a central valve for camshaft adjusters, in which the valve portion 3 is arranged within a camshaft
and rotates with the latter, while the actuation unit 2 is fastened in the axial direction with respect to it, for example to a cylinder head or a cylinder-head cover.
Reference symbols
1 hydraulic valve
2 actuation unit
3 valve portion
4 coil former
4a coil carrier
4b closing body
4c connecting element
5 annular groove
6 sealing element
7 coil
8 material layer
9 plug connection
10 recess
11 first magnet yoke
12 armature guide sleeve
13 stop
14 housing
14a introduction orifice
14b first region
14c introduction chamfer
14d second region
15 tab
16 armature
17 second magnet yoke
18 tubular portion
19 annular portion
20 bottom
21 orifice
22 mounting flange
23 bore
24 edge
25 caulking
26 sealing ring
27 valve housing
28 control piston
30 clearances
31 control portion
32 spring element
33 tappet pushrod
35 first subspace
36 second subspace
37 sliding sleeve
38 rim
39 bearing face
40 groove
P inflow connection
T tank connection
A first working connection
B second working connection
d thickness
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