Abstract:
The invention realties to a hydraulic valve for phaser. In the hydraulic valve according to the invention a seal element is arranged so that a risk of a transition of oil from an oil cycle or a lubricant cycle of an internal combustion engine or a risk of hydraulic fluid from the hydraulic valve entering a coil of an actuator is avoided.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority from and incorporates by reference International Patent Application PCT/EP2015/066285 filed on Jul. 16, 2015 claiming priority from German Patent Application DE 10 2014 011 088.5 filed on Jul. 30, 2014. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a hydraulic valve for a cam phaser according to the preamble of patent claim  1 . 
       BACKGROUND OF THE INVENTION 
       [0003]    DE10 2009 022 869 already discloses a hydraulic valve for a cam phaser. This hydraulic valve includes a piston that is supported longitudinally movable along an inner running surface for distributing hydraulic fluid from a supply connection P to two adjacent operating connections A, B. The piston is longitudinally moveable by an electro magnetically actuatable actuator. The tank connection T is provided in an axial direction. 
         [0004]    DE10 2004 036 096 A1 shows a hydraulic valve in which the connection P-T-B-A are radially arranged. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    It is an object of the invention to provide a robust hydraulic valve for a cam phaser. 
         [0006]    The object is achieved according to the invention by a hydraulic valve for a phaser of a cam shaft, the phaser including a piston that is supported axially movable along a first inner running surface of a hydraulic bushing of the hydraulic valve and configured to distribute a hydraulic fluid from a supply connection to a first operating connection and a second operating connection that are arranged adjacent to each other, wherein the piston is axially movable by an electromagnetically actuatable actuator, wherein the electromagnetically actuatable actuator includes a hollow pole element which is configured to receive an armature that is axially movable in the hollow pole element, wherein a coil of the actuator envelops the hollow pole element at least partially so that applying a voltage to the coil causes a magnetic field to move the armature in the actuator, wherein the hydraulic bushing that is flowable by the hydraulic fluid is at least configured adjacent to the hollow pole element, wherein the hollow pole element has a reduced outer diameter in a portion of the coil so that the hollow pole element is configured as a pole core cone starting from the reduced outer diameter in a direction towards the hydraulic bushing and the hollow pole element is configured as a pole yoke in a direction oriented away from the hydraulic bushing, wherein the hydraulic bushing is received in a bore hole of a valve housing of the hydraulic valve, wherein the pole core cone includes a seal element in an end portion oriented towards the hydraulic bushing, which seal element seals the bore hole relative to the coil. 
         [0007]    Advantageous embodiments with useful and non-trivial improvements of the invention are defined by the respective independent claims. 
         [0008]    In the hydraulic valve according to the invention a pole element is configured to develop a magnetic field when a voltage is applied at a coil received in an actuator of the hydraulic valve which facilitates in a simple manner to magnetically separate a pole core cone and a pole yoke of the actuator. Thus, the pole element includes an exterior diameter contraction in the portion of the coil so that the pole yoke and the pole core cone are configured in one piece as a pole element while maintaining a functional required separation between the pole yoke and the pole core cone due to the exterior diameter contraction. Through a thin remaining connection bar the magnetic field can hardly be conducted to maintain the function. In another context diameter reductions are disclosed in U.S. Pat. No. 2,853.659, U.S. Pat. No. 6,498,416 B1 and JP57164371U. 
         [0009]    A sealing of the actuator, in particular of the coil relative to the hydraulic fluid of the hydraulic valve or of the hydraulic fluid in an armature carrying portion of the pole element is obtained by a seal element. Thus, the seal element is arranged in a portion of an end of the pole core cone oriented towards the hydraulic bushing. Advantageously the seal element is configured in the form of a typical O-ring. Thus, a sealing in particular of the coil relative to a possible penetration of hydraulic fluid is implemented in combination with a simple configuration of the pole element. Furthermore when a portion of the actuator including the pole element is in a portion of the internal combustion engine that is proximal to engine oil a safe separation of engine oil and hydraulic fluid is provided. 
         [0010]    The seal element is advantageously positioned at an enveloping surface of the pole core cone which is arranged oriented towards the valve housing. For a secure reception and positioning of the seal element the pole core cone includes an annular groove. The annular groove is configured at the enveloping surface along the circumference of the pole core cone. Alternatively the seal element can also be arranged in an annular groove. 
         [0011]    In another embodiment the pole core cone is receivable in the hydraulic bushing. This has the advantage that an essentially closed hydraulic valve can be provided so that an oil cycle or lubricant cycle of an internal combustion engine is separated from the oil which is provided within the electromagnetic actuator or partially within the hydraulic portion. 
         [0012]    Thus, the pole core cone is thus configured hollow cylindrical where it is oriented away from its conical point so that the hydraulic bushing is insertable into the pole core cone which implements a press fit between the pole core cone and the hydraulic bushing to provide a particularly tight and stable connection. 
         [0013]    The hydraulic bushing is made from an aluminum material. This has the advantage that the hydraulic bushing can be machined easily and the hydraulic bushing has the same thermal expansion coefficient as the valve housing into which the hydraulic bushing is inserted. The pole core cone is made from a ferrous material since the pole core cone has to be able to conduct a magnetic flux in order to be functional and has to be magnetizable. 
         [0014]    In order to establish a coaxial alignment between the pole yoke and the pole core cone with a particularly small tolerance the pole yoke and the pole core cone can be integrally fabricated in one piece in a particularly advantageous embodiment and can have a common diameter. 
         [0015]    However it is also possible to obtain a uniform continuous inner diameter of the inner running surface with other means. For example the pole yoke and the pole core cone can be made from two components which are welded together by a non-magnetizable weld and which are subsequently drilled with a common inner diameter. 
         [0016]    In another embodiment the hydraulic valve is configured so that the oil cycle of the internal combustion engine is separate from the hydraulic fluid of the actuator or the hydraulic bushing. Thus, an inner portion of the hydraulic valve is kept free from contaminants and abrasion particles of the lubricant cycle. A risk that an armature of the electromagnetic actuator that is movably received in the pole element binds due to a solid particle relative to an interior running surface in the pole yoke is decreased. Thus, a tight tolerance between the armature and the inner running surface in the pole yoke is feasible. This tight tolerance improves coaxial alignment errors and thus reduces transversal forces. Namely transversal forces increase with coaxial alignment errors. Using a tight tolerance, however, is only possible when no solid particles can lodge between the armature and the inner running surface. When solid particles bind at this location the armature can only be pulled clear by high magnetic forces. Thus the coil or the electro magnet have to be oversized by a large amount which is disadvantageous for efficiency and which in turn increases the detrimental transversal forces even further. The armature and/or the pole yoke can be provided at their surface with a non-magnetizable layer for separation purposes. Alternatively it is also possible to use a non-magnetizable pot shaped sleeve. Such pot shaped sleeves are disclosed for example in DE 10 2009 043 320 B4 and DE10 2010 061 219.7. An additional alternative for the pot shaped component is a pot shaped pole yoke which is as such already disclosed in U.S. Pat. No. 6,202,699 B1. 
         [0017]    In order to achieve a hydraulic separation between the engine oil cycle and the electromagnetic actuator an axial sequence of the connection in the order T 1 -A-P-B-T 2  is advantageous. Thus, it is particularly advantageous that the tank connections T 1  and T 2  have a lower pressure than the supply connection P and the operating connections A, B so that virtually pressure free tank connections T 1  and T 2  are arranged between the high pressure portion and the virtually pressure free inner portion of the hydraulic valve wherein the tank connections T 1  and T 2  run the contaminated engine oil outward to the tank and through the oil filter. 
         [0018]    According to an advantageous embodiment of the invention the hydraulic valve of the cam phaser is configured as an external or non-central hydraulic valve, The typical non-central hydraulic valves according to the connection sequence T 1 -A-P-B-T 2  do not have an axial inlet/outlet of oil. Besides the non-central hydraulic valves there are central valves that are radially arranged within the rotor hub of the cam phaser. The invention can also be used as a matter of principle for central valves with some disadvantages. 
         [0019]    Since the inner portion for the hydraulic valve according to the invention is free from the oil pressure of the supply connection P, the piston is not exposed to any hydraulic axial forces. 
         [0020]    Additional advantages of the invention can be derived from the dependent patent claims, the description and the drawing figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The invention is subsequently described based on two embodiments with reference to drawing figures, wherein: 
           [0022]      FIG. 1  illustrates a cam phaser in a sectional view; 
           [0023]      FIG. 2  illustrates a semi-sectional view of a hydraulic valve o adjusting the cam phaser according to  FIG. 1 ; and 
           [0024]      FIG. 3  illustrates a detail of  FIG. 2  in an area of the actuator of the hydraulic valve. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    A cam phaser  14  according to  FIG. 1  is used to continuously adjust an angular position of a cam shaft  18  of a non-illustrated internal combustion engine relative to a drive wheel  2  during operation of the internal combustion engine. Rotating the cam shaft  18  moves opening and closing times of gas control valves of the internal combustion engine so that the internal combustion engine develops optimum power at a respective speed. 
         [0026]    The cam phaser  14  includes a cylindrical stator  1  which is connected torque proof with the drive wheel  2 . In the illustrated embodiment the drive wheel  2  is a chain sprocket over which a chain is run that is not illustrated in more detail. The drive wheel  2  however can also be a timing belt cog over which a timing belt is run as a drive element. Through this drive element and the drive wheel  2  the stator  1  is drive connected with the crank shaft. 
         [0027]    The stator  1  includes a cylindrical stator base element  3  from which bars  4  protrude at an inside in a radially inward direction with uniform spacing there between. Between adjacent bars  4  gaps  5  are formed into which a pressure medium is introduced in a controlled manner through a hydraulic valve  12  that is illustrated in more detail in  FIG. 2 . Thus the hydraulic valve  12  is configured as a non-central hydraulic valve  12 . Blades  6  protrude between adjacent bars  4  wherein the blades protrude in a radially outward direction from a cylindrical rotor hub  7  of a rotor  8 . The blades  6  divide the intermediary spaces  5  between the bars  4  respectively into two pressure chambers, a first pressure chamber  9  and a second pressure chamber  10 . 
         [0028]    The bars  4  contact an outer enveloping surface of the rotor hub  7  with their faces in a sealing manner. The blades  6  in turn contact a cylindrical inner wall of the stator base element  3  with their faces in a sealing manner. 
         [0029]    The rotor  8  is connected torque proof with the cam shaft  18 . In order to adjust an angular position between the cam shaft  18  and the drive wheel  2  the rotor  8  is rotated relative to the stator  1 . Thus, depending on a desired direction of rotation the pressure medium in the first pressure chamber  9  or the second pressure chamber  10  is pressurized while a respective other pressure chamber, the second pressure chamber  10  or the first pressure chamber  9  is unloaded towards a tank. In order to pivot the rotor  8  relative to the stator  1  counter clockwise into the illustrated position the hydraulic valve  12  pressurizes an annular first rotor channel  23  in the rotor hub  7 . Additional second channels  11  lead from the first rotor channel  23  to the second pressure chambers  10 . 
         [0030]    The first rotor channel  23  is associated with a first operating connection A of the hydraulic valve  12 . In order to pivot the rotor  8  clockwise the hydraulic valve  12  pressurizes a second annular rotor channel  24  in the rotor hub  7 . This second rotor channel  24  is associated with a second operating connection B of the hydraulic valve  12 . The two rotor channels  23 ,  24  are arranged axially offset from one another with respect to a central axis  22  of the cam phaser  14 . From this second rotor channel  24  additional first channels  11 ′ lead into the first pressure chamber  9 . 
         [0031]    The cam phaser  14  is applied to the cam shaft  18  that is configured as a hollow tube  16 . Thus, the rotor  8  is slid onto the cam shaft  18 . The cam phaser  14  is pivotable by the electromagnetically actuated hydraulic valve  12  that is illustrated in  FIG. 2 . 
         [0032]    The electromagnetically actuated hydraulic valve  12  with a valve housing  65  includes an electromagnetic actuator  17  and a hydraulic bushing  15 . The hydraulic bushing  15  is configured in a bore hole  21  of the valve housing  65 . Within this hydraulic bushing  15  a hollow piston  19  is supported axially movable against a force of a compression coil spring  44  along an inner running surface  13 . Thus, the compression coil spring  44  is supported on one side at the piston  19  and on the other side the compression coil spring is supported relative to the housing at the hydraulic bushing  15  A shoulder  48  is provided as a contact for the compression coil spring  44  within the piston  19  wherein a radial spring support adjoins at an end of the piston  19 , 
         [0033]    An armature  20  of the electromagnetic actuator  17  contacts the piston  19  at an end of the hydraulic bushing  15  that is at an outside of the cam shaft, this means at a rear end of the hydraulic bushing  15 . 
         [0034]    The hydraulic bushing  15  includes five recesses that are axially offset from each other, a first recess  31 , a second recess  38 , a third recess  39 , a fourth recess  40  and a fifth recess  41 . Out of these the four recesses arrange on the axial outside, the fifth recess  41 , the second recess  38 , the third recess  39  and the fourth recess  40  form the two operating connections A, B and two tank connections T 1 , T 2 . The axially centrally located recess, the first recess  31 , forms the supply connection P. The supply connection P includes an inner ring groove on an inside of the first recess  31 , wherein a band shaped check valve  79  is inserted into the inner ring groove. This total of five recesses  41 ,  38 ,  31 ,  39 .  40  cooperates with three control grooves, a first control groove  28 , a second control groove  29 , and a third control groove  30  which extend circumferentially at an outside of the piston  19 . 
         [0035]    Thus, so called control edges are formed between the control grooves  28 ,  29 ,  30  and the adjacent axially outer recesses  41 ,  38 ,  39 ,  40 . These control edges define an amount of the hydraulic fluid that is run through, wherein a flow of hydraulic fluid can be cut off at these control edges almost entirely when the overlap is large enough. When the control edge is blocked a seal gap is formed between the piston  19  and the hydraulic bushing  15 . 
         [0036]    The fifth recess  41 , the second recess  38 , the first recess  31 , the third recess  39  and the fourth recess  40  are arranged in the sequence T 1 -A-P-B-T 2 . Put differently the axial sequence from the first inner running surface is as follows:
       the first tank connection T 1  for running hydraulic fluid out from the first operating connection A,   the first operating connection A for running hydraulic fluid into the first pressure chamber  9  of the cam phaser  14 ,   the supply connection P,   the second operating connection B for running hydraulic fluid into the second pressure chamber  10  of the cam phaser  14  which second pressure chamber is oriented opposite to the first pressure chamber  9 , and   the second tank connection T 2  for running hydraulic fluid out from the second operating connection B.       
 
         [0042]    The two outer recesses, the fifth recess  41  and the fourth recess  40  are associated with the two tank drains T 1 , T 2 . The second recess  38  is associated with the first operating connection A and provided for running hydraulic fluid into the second pressure chambers  10  of the cam phaser  14  that are associated with a first phasing direction. Furthermore hydraulic fluid can be pumped to the first tank drain T 1  through this first operating connection A. 
         [0043]    The third recess  39  that is positioned between the fourth recess  40  associated with the second tank drain T 2  and the first recess  31  associated with the supply connection P is associated with the second operating connection B and provided for running hydraulic fluid into the first pressure cavities  9 . Furthermore hydraulic fluid can be pumped through this operating connection B from the first pressure cavities  9  to a second tank drain T 2 . 
         [0044]    In order to separate the three control grooves  28 ,  29 ,  30  four bars, a first bar  61 , a second bar  62 , a third bar  63  and a fourth bar  64  are formed at an outside of the piston  19 . In the illustrated center blocking position of the piston  19  the two operating connections A, B are loaded with more pressure, than a drain pressure of the hydraulic fluid. Thus, the cam phaser  14  is fixated in this angular position. In this center blocking position the two recesses of the two operating connections A, B are covered by the second bar  62  and the third bar  63 . 
         [0045]    A third control edge  68  of the second bar  62  and a fourth control edge  69  of the third bar  63  have a smaller overlap than the control edges oriented away from each other, a second control edge  67  of the second bar  62  and a fifth control edge  70  of the third bar  63 . 
         [0046]    The first control groove  28  and the third control groove  30  are thus defined by first control edge  66  or the sixth control edge  71  towards the operating connections A, B wherein the control edges  66  and  71  are oriented towards each other at the first bar  61  and at the fourth bar  64 . The first control groove  28  and the third control groove  30  are defined in an axial outward direction by the bars adjoining the first control edge  66  or the sixth control edge  71 , thus by the first bar  61  and the fourth bar  64 . 
         [0047]    Between the first inner running surface  13  and the first bar  61  or the fourth bar  64  radial gaps are configured over a first gap length  73  and a second gap length  74 . 
         [0048]    Through these gap lengths  73 ,  74  thus a limited amount of sealing is provided relative to an inner space  75  within the hollow piston  19 . 
         [0049]    This inner space  75  within the piston  19  connects two spaces that are arranged axially adjacent to the piston  19 , a third space  77  and a fourth space  78 . The fourth space  78  that is arranged oriented away from the actuator  17  is hydraulically closed by a closure  76 . This closure  76  closes the hydraulic bushing  15  similar to a base of a pot. The third space  77  is closed by a pot shaped component adjoining the first inner running surface  13  wherein the pot shaped component is configured as a pole can  37 . 
         [0050]    Thus, the entire inner space  75  within the hollow piston  19  and within the pole can  37  is hydraulically separated from the outer control grooves that are only exposed to a low pressure, the first control groove  28  and the third control groove  30  or the tank connections T 1 , T 2  connected thereto. However, the relatively high pressure at the supply connection P is separated by the two axially interior bars, the second bar  62  and the third bar  63  from the exterior control grooves, the first control groove  28  and the third control groove  30 . Due to these separations and the low pressure in the axially outer control grooves  28 ,  30  there is hardly any exchange of hydraulic fluid between a first space  26  arranged axially in front of an armature  20  of the actuator  17  which armature is axially movable within the pole can  37  and a second space  27  formed axially behind the armature  20 . Thus, a gap with very tight tolerance between the armature  20  and a second inner running surface  43  of the pole can  37  is kept substantially free from contaminant particles from the engine oil lubrication cycle to which the cam phaser  14  is connected. 
         [0051]    The hydraulic bushing  15  is axially fixated at a pole core cone  32  of the pole can  37 . Thus, the hydraulic bushing  15  is pressed into the pole core cone  32 . The magnetizable pole core cone  32  is fabricated integrally in one piece with a pole yoke  33  of the pole can  37 . In order to still provide a functional separation between the pole core cone  32  and the pole yoke  33  the pole core cone  32  tapers at the cone tip  34  into a reduced outer diameter  35 . This reduced outer diameter  35  adjoins the pole yoke  33 . The pole yoke  33  is configured closed with a base  36 . Thus, the pole can  37  whose inside  42  forms the second inner running surface  43  for the armature  20  forms the pole core cone  32 , the pole core yoke  33  and the base  36  that is provided with a continuous interior diameter  82 . 
         [0052]    An electrical coil  45  is provided that radially envelops the pole can  37  This coil  45  is made from a plastic coil carrier  46  to which the wire winding is applied. 
         [0053]    The pole can  37  includes an externally circumferential annular groove  47  at an end of the pole can that is oriented towards the hydraulic bushing  15 . A seal element  49  configured as an O-ring is inserted into this annular groove  47 . The O-ring  49  seals the pole can  37  against the bore hole  21 . Thus, hydraulic fluid cannot exit within the bore hole  21  at an opening portion of the bore hole  21  oriented towards the actuator  17 . Alternatively the O-ring  49  can also be positioned in an annular groove in the bore hole  21  and can seal in a radial direction at the pole can  37 . 
         [0054]    The armature  20  includes a pass through bore hole  25  which assures that the hydraulic fluid or a mix of hydraulic fluid and air can be exchanged between the first space  26  and the second space  27 . A first face  51  of the armature  20  is oriented towards a second face  52  of the hydraulic bushing  15 . A pole core ring  50  is impressed between the faces  51 ,  52  within in the pole can  37 . This pole core ring  50  is magnetizable like the pole core cone  32  and is thus arranged in the magnetic field which is generated when a voltage is applied to the coil  45 . 
         [0055]    Since the piston  19  includes control grooves that are associated with the tank connections T 1 , T 2  at both ends of the piston, the first control groove  28  and the third control groove  30 , the first tank connection T 1  and the second tank connection T 2  are defined in an axially outward direction by the first bar  61  or the fourth bar  62 . Thus, the spaces axially adjoining the first bar  61  and the fourth bar  64 , the third space  77  and the fourth space  78  are hydraulically separated from
       the first tank connection T 1 ,   the first operating connection A,   the supply connection P   the second operating connection B, and   the second tank connection T 2     in any position of the piston.       
 
         [0062]    The piston  19  is provided as a turned component which is supported at the armature  20  by a support element  80 . The support element  80  can be configured as a plunger that is alternatively pressed into the piston  19  or into the armature  20 , wherein the plunger includes recesses for passing hydraulic fluid between the inner space  75  and the third space  77 . 
         [0063]    Since the inner portion within the hydraulic valve  12  is free from oil pressure from the supply connection P no hydraulic axial forces impact the piston  19 . 
         [0064]      FIG. 3  illustrates a detail of  FIG. 2  in the portion of the actuator  17 . Thus, it is evident that the armature  20  is supported over a length  81  along the second inner running surface  43 . Over this length the pole can  37  is fabricated integrally in one piece with a uniform inner diameter  82 . The length  81  extends axially over 
         [0065]    the pole yoke  33 , 
         [0066]    a throttling location at the pole yoke  33 , and 
         [0067]    at least a portion of the pole core cone  32 . 
         [0068]    The throttling location corresponds to the reduced outer diameter  35 . 
         [0069]    The armature  20  includes a uniform armature diameter  84  over an armature length  83 . The armature  20  is displaceable between two axial stops wherein one stop is formed by the base  36  of the pole can  37  and the other axial stop is formed by an anti-stick disc  85  which contacts the pole core ring  50 . 
         [0070]    The armature includes a separation layer at its enveloping surface. This separation layer separates the armature  20  from the pole can  37 . A coating of this type can be for example nickel-phosphor or chemical nickel. Furthermore Teflon, a sliding lacquer or plasma nitrite coating are feasible. These various coatings can be alternatively applied also on the second inner running surface  43  in order to magnetically separate the armature  20  from the pole can  37 . A coating on both sides is possible, however, the alignment errors or coaxial tolerances and thus transversal forces increase with a thickness of the coating. High transversal forces cause a high level of wear or abrasion between the armature  20  and the pole can  37  in addition to low efficiency. A support of this type where the coating forms the separation layer and simultaneously forms the bearing layer over the enveloping surface of the armature is also designated as belly bearing. 
         [0071]    In an alternative embodiment additional check valves are provided in the hydraulic valve  12  which facilitates using alternating cam torques for a quick adjustment or an adjustment with low oil pressure. The oil pressure is very small for example when many consumers branch off from the hydraulic loop or when the oil pump is sized very small for reducing fuel consumption. Small torques of this kind can be below 1 bar. 
         [0072]    The check valve does not have to be configured as a band shaped check valve which is inserted into an annular groove of the hydraulic valve  12 . It is also possible for example to configure the check valve as a ball check valve in a funnel shaped valve seat which is known already from DE 10 2007 012 967 B4. 
         [0073]    In an alternative embodiment the pole core ring  50  has an inner diameter that is small relative to its outer diameter. Thus, it is however assured through at least one pass through opening  86  that hydraulic fluid can be exchanged between the spaces  77 ,  27 . 
         [0074]    The described embodiments are merely exemplary embodiments. A combination of the described features to obtain different embodiments is also feasible. Additional features of the elements forming part of the invention that are not described can be derived from geometries of the components illustrated in the drawing figures. 
       REFERENCE NUMERALS AND DESIGNATIONS 
       [0000]    
       
           1  stator 
           2  drive wheel 
           3  stator base element 
           4  bar 
           5  intermediary space 
           6  blade 
           7  rotor hub 
           8  rotor 
           9  first pressure chamber 
           10  second pressure chamber 
           11  channel 
           11 ′ channel 
           12  hydraulic valve 
           13  first inner running surface 
           14  cam phaser 
           15  hydraulic bushing 
           16  hollow tube 
           17  actuator 
           18  cam shaft 
           19  piston 
           20  armature 
           21  bore hole 
           22  central axis 
           23  first rotor channel 
           24  second rotor channel 
           25  pass through bore hole 
           26  first space 
           27  second space 
           28  first control groove 
           29  second control groove 
           30  third control groove 
           31  first recess 
           32  first pole core cone 
           33  pole yoke 
           34  cone tip 
           35  reduced outer diameter 
           36  base 
           37  hollow pole element 
           38  second recess 
           39  third recess 
           40  fourth recess 
           41  fifth recess 
           42  inside 
           43  second inner running surface 
           44  compression coil spring 
           45  coil 
           46  coil carrier 
           47  annular groove 
           48  shoulder 
           49  seal element 
           50  pole core ring 
           51  first face 
           52  second face 
           53  first control edge 
           54  second control edge 
           55  third control edge 
           56  fourth control edge 
           57  fifth control edge 
           58  sixth control edge 
           59  seventh control edge 
           60  eighth control edge 
           61  first bar 
           62  second bar 
           63  third bar 
           64  fourth bar 
           65  valve housing 
           66  first control edge 
           67  second control edge 
           68  third control edge 
           69  fourth control edge 
           70  fifth control edge 
           71  sixth control edge 
           72  - 
           73  first gap length 
           74  second gap length 
           75  inner space 
           76  closure 
           77  third space 
           78  fourth space 
           79  check valve 
           80  support element 
           81  length 
           82  inner diameter 
           83  armature length 
           84  armature diameter 
           85  anti-stick disc 
           86  pass through 
         A first operating connection 
         B second operating connection 
         P supply connection 
         T 1  first tank drain 
         T 2  second tank drain