Abstract:
Controllable solenoid valve in which, due to the interaction between a magnetic force caused by an electrical flow and a spring force acting against the magnetic force, at least one first sealing body in the interior of a valve housing is displaced in axial direction between two final positions whereby moving relative to its first sealing seat. The interior extends from one electromagnet to a connection. To enable, in a simple manner, a specific reproducible influencing of the sequence speed of cylinder controls in hydraulic drives and to prevent uncontrolled movements by these drives, the first sealing seat up to the first sealing body is provided with an axially extending cylindrical housing inside of which a slide is axially displaced according to the electrical flow. The cylindrical housing comprises radially oriented passages, whereby these passages are closed if the first sealing body is located in a final position in its first sealing seat or in the immediate vicinity of the first sealing seat, and the passages are opened if the first sealing body is located in the opposite final position.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The invention relates to a controllable solenoid valve according to the species of the patent claims. These kinds of valves are used in such applications that intend to influence the sequence speed of cylinder controls in hydraulic drives, in particular in automatic convertible tops.  
         [0002]     For the control of convertible top sequences, 3/2 solenoid valves are used in poppet design which are for example described in DE 3722344 A1. To prevent refluxes, an additional check valve can be installed at the pump connection or partly integrated into the solenoid seat valve, see EP 0 565 190 A1. In practical applications, weights and cinematic forces determine the movement sequences. In certain positions the own weight of the top already causes a movement. Said forces lead to unwanted high movement speeds and cause the top to slide into the end stops without being slowed-down, thus causing disturbing noise and rebounds.  
         [0003]     In vehicles, spring or buffer elements reduce this rebound noise only in an imperfect manner. Throttles fixed in the tank adapter of the individual cylinder are known as hydraulic absorbing means. But the hydraulic throttling has several disadvantages. As the throttle effect does not change in the whole movement range, it represents a compromise; the two options are a complete rapid motion sequence and a relatively unbraked run into the end position or a completely slow motion sequence and a relatively soft rebound. Moreover, the adjustment of the hydraulic throttles is a time-consuming and labor-intensive process, because the components produced cannot be modified later. Mostly, different throttle cross sections are required within the valve connection system to get an optimum sequence. This development leads to the most expensive variant and involves the risk of mix-ups in the production process; thus, it will require more efforts. Moreover, the rigid adjustment is principally suited for one specific kind of application only; each new application requires new components.  
         [0004]     A controllable pressure-limiting valve inserted into the tank connection of a cylinder can be used as another hydraulic solution. Thus, a counterpressure is built up which also slows down the displacement of oil out of the cylinder chamber. But in this way an additional solenoid valve is to be used which requires a corresponding space, electrical energy and trigger electronic units.  
       SUMMARY OF THE INVENTION  
       [0005]     The aim of the present invention is to correct said faults and to enable, in a simple manner, a specific reproducible influence on the sequence speed of cylinder controls in hydraulic drives and to prevent uncontrolled movements caused by these drives.  
         [0006]     According to the invention, this task is tackled by the elements of the first patent claim. The elements of the subclaims support the further advantageous development and specification of the invention. Thanks to the possibility to select and adjust the electric triggering system and to modify a solenoid valve seat, a cylinder control for hydraulic drives can be designed in a considerably simplified and reliably functioning manner. In addition to this, it allows the demonstration of the proportional action of the throttling of a liquid flow.  
         [0007]     In the throttling range, the magnet of the solenoid valve is acting against a relatively stiff spring (ca. 5 to 20 N/mm). The value of electric current supplied to the solenoid valve determines the position of the valve locking body or sealing body. Basically, the components can be arranged in such a way that in the non-energized state of the electromagnet the connection between two connection openings of the solenoid valve is either opened or closed. If for a corresponding valve the connection of the two connection openings is opened in the non-energized state of the electromagnet and the pressure spring has its maximum possible extension, the slide or piston connected to the solenoid armature closes radial-oriented passages (boreholes, long holes, etc.) with the current increasing. Thus, the flow cross section between the connection openings is reduced. The throttle effect increases and the cylinder movement is specifically influenced. At the end of the control range, only gap leakages between the two connection openings are possible. This invention also includes the options to close only one passage or different passages in a cylindrical housing by means of the slide.  
         [0008]     For the process just described, the slide moves within the cylindrical interior of a housing of a solenoid valve, which can preferably be a 3/2 or 2/2 solenoid valve. At one end of this valve, the electromagnet is positioned and at its other end a pump connection is installed prolonging the cylindrical interior. For a fixed, maximum switching current, the solenoid drive of the slide overcomes the pressure forces at the pump connection and thus it connects the pump connection and the radial connection opening in the housing located most closely to it. At the same time, the communication between the two radial connection openings is interrupted by another sealing element in such a way that even leakages are avoided. Then, a triggered cylinder can be moved towards the opposite direction.  
         [0009]     According to the invention, the control function is achieved without needing additional solenoid valves and with the minimum possible space requirements. It ensures a high grade of reproducibility for the manufacturing process and a simple replacement for retrofitting purposes. Even for devices that have already been installed, modifications or optimizations of the movement sequences only require the adjustment of the electric or electronic trigger action. Adjustments and fine adjustments can be made during the manufacturing process by means of an adjuster provided at the slide. The electrically adjustable throttling allows various applications of the invention for control tasks waiting to be solved as a far as a solenoid valve is used. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     In the following, three design examples explain the invention and its application in detail in a schematic drawing. They show:  
         [0011]      FIG. 1  an inventive solenoid valve in an axial section and in a non-energized state,  
         [0012]      FIG. 2  an inventive solenoid valve according to  FIG. 1  supplied with a low current,  
         [0013]      FIG. 3  an inventive solenoid valve according to  FIG. 1  supplied with a medium current,  
         [0014]      FIG. 4  an inventive solenoid valve according to  FIG. 1  supplied with a high current,  
         [0015]      FIG. 5  an inventive solenoid valve according to  FIG. 1  supplied with a maximum current,  
         [0016]      FIG. 6 a  diagram demonstrating the dependence of the flow on the value of the coil current,  
         [0017]      FIG. 7 a  diagram demonstrating the dependence of the slide position on the value of the coil current,  
         [0018]      FIG. 8 a  first example for the application of the inventive solenoid valve, and  
         [0019]      FIG. 9 a  second example for the application of the inventive solenoid valve. 
     
    
     DETAILED DESCRIPTION  
       [0020]      FIG. 1  shows a solenoid valve  10  which principally consists of an electromagnet  11  with an electric control unit  12  and a housing  13  provided with connection openings  14 ,  15  as well as a connection  16 . One end  17  of the housing  13  located opposite to the connection  16  projects into the electromagnet  11  and is fixed to it by pins  18  or screws. The two components  11  and  13  could also be connected with each other by a screwed joint.  
         [0021]     The electromagnet  11  is a wire-wound coil  20  the wire of which is wound around a hollow winding body  19  made of insulation material. If an electric current flows through the coil  20 , the coil generates a magnetic field that depends on the value of this current flow. Along its circumference, the coil  20  is provided with an electrically insulating and heat-dissipating extrusion coating  21 . At one terminal  22  of the winding body  19 , a plug-type connector  23  is provided for a line  24  leading to the electric control unit  12  that supplies a current of changing values to the coil  20 .  
         [0022]     In a bush  25  fitted into the winding body  19  a guiding pipe  26  for an armature  27  of the electromagnet  11  is located and is fixed to the end  17  of the housing  13  at one end and is closed at its other end. A sealing ring  30  seals the fixed connection between the housing  13  and the guiding pipe  26 . The armature  27  is provided with a longitudinal borehole  28  for compensating the pressure between the spaces before and behind the armature. A bow  29  contacts the end of the bush  25  projecting out of the electromagnet  11  and surrounds the insulated wire coil  20  at least partly so as to contact the valve housing  13 , too. The bush  25  transmits the magnetic flux from the bow  29  to the armature  27 . The bow  29  passes the magnetic force further to the housing  13  and ensures the magnetic reflux. The front side of the housing  13  facing the armature  27  is perfectly designed to have an optimum influence on the magnetic forces.  
         [0023]     The components  25 ,  29 ,  13 ,  27  form a magnetic circuit. A pin  31  is fixed to the armature  27 , for example by a screw joint, and projects through an axial borehole  32  in the housing  13  into an also axially oriented interior  33  and actuates a slide  34  there. The interior  33 , into which the connection openings  14 ,  15  to the tank reflux  35  or to the cylinder (consumer)  36  lead, is provided with a ring-shaped shoulder  37  between the connection openings. This shoulder is formed by an extension of the interior  33  towards the connection  16  of the pump. The connection opening  15  and the connection  16  are provided with filters  55  that prevent contaminating substances possibly contained in the liquid from getting into the valve  10 .  
         [0024]     At its end opposite to the pin  31  the slide  34  has a sealing ball (sealing element)  38  to which a (second) sealing seat  39  belongs that is attached as a front piece to a cylinder  40  which has been installed in axial position and is opened at its side towards the electromagnet  11 . Into the open cylinder  40 , which is fixed in the interior  33  and is provided with radial boreholes  41  (holes, longitudinal holes, passages or similar holes) that can have different diameters for current-flow reasons, the slide  34  partly projects to be guided so that it releases the radial boreholes  41  in a non-energized state of the electromagnet  11  and closes them if the electromagnet  11  is highly energized. The slide  34  is surrounded by a helical spring  42  supported at one side by the cylinder  40  and at its other side by an adjusting element  43  which is screwed onto the pin end of the slide. The adjusting element  43  can also be fixed to the slide  34  in another way. Neither must the spring  42  principally be formed like a helical spring nor be arranged around the slide  24 . For example, it is also possible that it surrounds the armature of the electromagnet.  
         [0025]     A guiding body  44  for an axially arranged and moveable tappet  45  is provided with liquid channels and pressed against the shoulder  37 . This tappet  45  terminates in the sealing seat  39  at one end and at its other end it terminates in a (second) sealing seat  46  for another sealing ball (sealing element)  47  and acts upon the sealing ball  47 , if required. Said ball is supported by a telescopic ball bearing traveler  48  located within a cylinder  49  which is fixed at the sealing seat  46  and is open towards the pump connection  16 . Said cylinder is fitted into the extended interior  33  and contains a sealing seat  50  itself for the sealing ball  47 , which is lifted from the sealing seat  50  due to the pump pressure. Moreover, sealing rings  51 ,  52 ,  53  are provided at the housing  13  for fitting the solenoid valve  10  into a device (not shown). For this purpose, the sealing ring  51  is used as a sealing element to the outside, the sealing ring  52  seals the space between the two connection openings  14  and  15  and the sealing ring  53  seals the space between the connection opening  15  and the connection  16 .  
         [0026]     The armature  27 , the pin  31  and the slide  24  are mainly arranged in coaxial position to a common geometric axis, whereby the pin  31  projects into a recess at the armature  27  and the spring  42  ensures its permanent connection to the armature  27 . Connections between the individual components differing from the ones shown are possible.  
         [0027]     In the representation given in  FIG. 1 , the solenoid valve  10  is not energized (I 0  in  FIG. 6 ). The electromagnet  11  is not switched on, the armature  27  is in the position shown, the adjusting element  43  contacts the appropriate front face of the cylindrical interior  33 , the radial boreholes  41  are completely open, a medium can freely flow from the connection opening  15  through the sealing seat  39  to the connection opening  14 . If a current I is switched on by the control unit  12 , the armature  27  moves towards the direction indicated by an arrow  54 . If first a current I 1  ( FIG. 6 ) which is considered to be low for the valve  10  is supplied, i.e. the solenoid valve  10  is in a low-energized state, the armature  27  will move by also a short distance only towards the direction indicated by the arrow  54  till the magnetic force and the force of the spring  42  are balanced. This condition is shown in  FIG. 2  in which the adjusting element  43  is lifted from the appropriate front face of the interior  33 , the larger one of the radial boreholes  41  is partly closed by the displacement of the slide  34 , the flow of the liquid from the connection opening  15  to the connection opening  14  is slightly throttled by the valve  10 . The sealing ball  38  is still far away from the sealing seat  39  belonging to it, whereas the sealing ball  47  is located in the sealing seat  46  and prevents the flow from the connection opening  15  to the connection  16 .  
         [0028]     If a current I 2  that is considered medium-high for the valve  10  is supplied by means of the control unit  12 , the solenoid valve  10  is carrying a medium-high current according to the representation in  FIG. 3 . The armature  27  and with it the slide  34  move into a balanced position due to the now effective magnetic force and the counterforce of the spring  42 . In this position, the slide  34  closes the larger radial borehole  41  completely and the smaller radial borehole ( 41 ′ in  FIG. 3 ) partly. Thus, the flow from the connection opening  15  to the connection opening  14  is stronger throttled (medium throttling) than in  FIG. 2 . The sealing ball  38  is not yet located in the appropriate sealing seat  39  and the sealing ball  47  is still closing the sealing seat  46 .  
         [0029]     If a current I 3  that is considered high for the solenoid valve  10  is supplied, a balanced condition between the magnetic force and the spring force will only be reached, if the slide  34  completely closes the two radial boreholes  41 . The sealing ball  38  has not yet closed the sealing seat  39  and the sealing ball  47  is still in the sealing seat  46 . In this highly energized state of the solenoid valve  10 , the flow from the connection opening  15  to the connection opening  14  is throttled in such a manner that only a leaking liquid is flowing (see  FIG. 4 ).  
         [0030]     If the solenoid valve  10  is supplied with a maximum current I 4  by the control unit  12 , the force of the electromagnet  11  is absolutely stronger than the force of the helical spring  42  and presses the sealing ball  38  against the sealing seat  39  via the slide  34  (see  FIG. 5 ). At the same time, the ball  36  presses the ball  47  out of its sealing seat  46  by means of the bolt  45  so that the flow from the connection opening  15  to the connection opening  14  is completely interrupted and the flow from the connection  16  to the connection opening  15  is opened. In this case, a triggered cylinder could be actuated into the opposite direction. It goes without saying that the states demonstrated in the  FIGS. 2 through 5  are only given as examples, that the grading can vary according to the individual application and demand, it can be considerably finer or even rougher or also random. The control and thus the adjustment of the armature  27  or the slide  34  can also be performed in a continuous or discontinuous mode.  
         [0031]     With the help of a diagram,  FIG. 6  demonstrates the flow Q (P) between the connection openings  15  and  14  as a function of the relevant coil current. The diagram makes clear that—depending on the flow rate—an increasing pressure difference is built up towards an arrow  56  between the connection openings  15  and  14 . For this solenoid valve  10 , the pressure can increase from 50 bar for the smallest flow volume to 200 bar for the largest flow volume.  
         [0032]     The diagram presented in  FIG. 7 , in which the electric current is increased from 0.2 A to 2 A in 0.2 ampere steps, clearly demonstrates the positions  57 - 60  of the slide  34  in which the magnetic force and the helical spring force are in a balanced condition and which correspond to the  FIGS. 1 through 4 . Thus, the solenoid valve  10  is in a non-energized state in position  57  in which the flow from the connection opening  15  to the connection opening  14  is not throttled and the flow from the connection  16  to the connection opening  15  is blocked. Whereas the flow in the other positions  58 ,  59 ,  60  is more and more throttled due to the low, medium and high currents I 1 , I 2 , I 3  connected to the wire-wound coil  20 , the flow connection between the connection  16  and the connection opening  15  is kept blocked. Only in the position  61 , in which the balanced condition of the forces of the electromagnet  11  and the helical spring  42  is not important any longer, the flow connection between the connection openings  15  and  14  is definitely blocked and the flow connection between the connection  16  and the connection opening  15  is opened due to the predominating magnetic force. If for example, the total way of the slide  34  from position  57  to position  61  is about 1 mm and the partial way from position  60  to position  61  is about 0.3 mm, the shorter slide way makes possible lower baffle effects and a smoother running of the slide  34  into the position  61  in relation to the state of the art.  
         [0033]     The  FIGS. 8 and 9  show two examples for the application of the inventive valve arrangement for the speed- or pressure-dependent control of the relative movement of a piston within a cylinder. In  FIG. 8 , a solenoid valve  62  is designed as a 3/2 valve and is connected to a liquid tank  67  and a cylinder  68  via hydraulic lines  63 ,  64 ,  65  which are provided with filters for removing possible dirt out of the flowing medium. A piston  69  one side of which is under the pressure of a spring  77  slides in the cylinder  68 . The flow directions of the medium through the lines  63 ,  64 ,  65  are indicated by the arrows  70  beside them. In the supply line  63  a pump  71  driven by the motor M is installed and, subsequent to it in flow direction, a connection for a pressure control valve  72  is arranged to avoid overpressures in the downstream system between the supply line  63  and the discharge line  64 . An electrical control unit  73  is connected to the solenoid valve  62  and the piston  69  via electrical lines  74 ,  75  with a transducer  76  being installed in the line  75 .  
         [0034]     The pump  71  generates for example a pressure of  200  bar and a possible volume flow of 1 liter/min within the system. If the maximum permissible system pressure is exceeded, the pressure control valve  72  will open and will allow the medium to escape into the tank  67  until the permissible system pressure will be reached again. If the 3/2 valve  62  is in the maximally energized state (switched), the medium (hydraulic oil) will flow from the pump  71  via the valve  62  into the cylinder  68 , and the piston  69  will be pressed out of the cylinder. During this process, the connection from the valve  62  to the tank  67  is closed as described above. If the solenoid valve  62  is in a non-energized state (rest position), the medium will flow without being throttled from the cylinder  68  via the valve  62  into the tank  67 , and the piston  69  will move into the cylinder. The connection between the pump  71  and the valve  62  is closed during this process.  
         [0035]     If the solenoid valve  62  is supplied with a current in the range I 0 &lt;I&lt;I 4  ( FIGS. 2-5 ), that means that the slide  34  is within the control range, the medium will flow from the cylinder  68  via the valve  62  into the tank  67 . Thus, the piston  69  is caused to move into the cylinder  68 . The movement of the piston  69  is for example effected by the weight of a convertible top (not shown). Due to the position of the slide  34  (in the  FIGS. 2-5 ) within the solenoid valve ( 10 )  62  and the throttling combined with it, a certain volume flow is reached from the cylinder  68  into the liquid tank  67 . This volume flow is directly proportional to the speed of the piston. The control unit  73  compares the speed measured at the piston  69  with a default value given by the specific application. If the two values are different, the control unit  73  calculates a new value for the volume flow through the valve  62  with the help of existing data (such as speed, cylinder dimensions, present valve current, valve characteristic curve, etc.). This value will be transferred to the valve. If the speed measured is too low, the valve current will be decreased. Consequently, the magnetic force will decrease, the spring  42  will press back the slide  34  ( FIGS. 2-5 ), and the throttling will be reduced. The volume flow and thus the piston speed will be increased correspondingly. If the piston speed measured is too high, the current supplied to the valve  62  will be raised. Therefore, the magnetic force will increase, the slide  34  will move against the force of the spring by a certain amount, the throttling will increase, the volume flow and thus the cylinder speed will be reduced.  
         [0036]     The cylinder speed can be kept at a constant value or a defined speed-time-curve can be maintained.  
         [0037]     Unlike in  FIG. 8 , in  FIG. 9  the pressure at the cylinder  68  is controlled. For this purpose, supply lines  631  and  632  lead to the chambers  681  and  682  of the cylinder  68 . A controllable solenoid valve  621  is installed in the supply line  631  and a solenoid valve  622  without control is installed in the supply line  632 . In our example, both valves are  3 / 2  solenoid valves. Return lines  641  and  642  lead from the valves  621  and  622  to the tank  67 . Electrical lines  74  or  751  and  752  lead from a control unit  73  to the solenoid valve  621  or via transducers  761  and  762  to the chambers  681  and  682  of the cylinder  68 . The designations already mentioned for  FIG. 8  apply to the rest of the elements.  
         [0038]     It is assumed that the pump  71  is running, the valve  622  is switched and the valve  621  is energized. Referring to the  FIGS. 2-5 , I 0 &lt;I&lt;I 4  applies for the current; that means that the slide  34  is within the control range. The medium flows from the pump  71  via the valve  622  into the chamber  682  of the cylinder  68 . This flow presses the piston  69  to the right in the drawing and the medium being in the chamber  681  is pressed via the valve  621  into the tank  67 . Due to the position of the slide  34  in the solenoid valve  621  and the thus caused throttling of the medium flow by the valve  621 , a certain pressure is reached in the line  651  from the cylinder  68  to the valve  621 . The pump  71  determines the pressure in the line  652  between the valve  622  and the cylinder  68 . The pressure difference between the lines  651  and  652  is directly proportional to the cylinder force.  
         [0039]     The control unit  73  compares the pressure difference between the lines  651  and  652  with a default value depending on the specific application. If the pressure measured deviates from the default value, the control unit  73  calculates a new value for the current at the valve  621  with the help of the data saved and it transfers this value to this valve. If the pressure measured is too low, the current at the valve  621  will be increased. Consequently, the slide  34  increases the throttling of the medium flow by an appropriate amount that in its turn causes a sufficient increase of the pressure and therefore an increase of the cylinder force. If the pressure measured is too high, the current at the valve  621  will be reduced. As a result, the slide  34  decreases the throttling of the medium flow by an appropriate amount that in its turn causes an adjusted reduction of the pressure down to a pressure balance and thus also a reduction of the cylinder force.  
         [0040]     The cylinder force can also be kept at a constant value or a defined force-time-curve can be maintained. It is also possible to limit the force.  
         [0041]     In the previous explanations, the magnetic force has a minimum value, zero included, if the passages are opened, and a maximum value if the passages are closed. Vice versa, it is part of the invention that the magnetic force can also have a maximum value for opened passages and a minimum value, zero included, for closed passages. In the last given case, a special valve design is possibly required.  
         [0042]     All elements presented in the description, the subsequent claims and the drawing can be decisive for the invention both as single elements and in any combination.  
       LIST OF REFERENCE NUMERALS  
       [0000]    
       
           10  solenoid valve  
           11  electromagnet  
           12  control unit  
           13  housing  
           14 , 15  connection openings  
           16  connection  
           17  end  
           18  pins  
           19  winding body  
           20  wire-wound coil  
           21  extrusion  
           22  end  
           23  plug-type connector  
           24  line  
           25  bush  
           26  guiding pipe  
           27  armature  
           28  longitudinal borehole  
           29  bow  
           30 ,  51 ,  52 ,  53  sealing rings  
           31  pin  
           32  axial borehole  
           33  interior  
           34  slide  
           35  tank reflux  
           36  cylinder (consumer)  
           37  shoulder  
           38 ,  47  sealing balls  
           39 ,  46 ,  50  sealing seats  
           40 ,  68  cylinders  
           41 ,  41 ′ boreholes  
           42  helical spring  
           43  adjusting element  
           44  guiding body  
           45  tappet  
           48  telescopic ball bearing traveler  
           49  cylinder  
           54 ,  56 ,  70  arrows  
           55 ,  66  filters  
           57 ,  58 ,  59 ,  60 ,  61  positions of the slide  
           62  solenoid valve  
           63 ,  64 ,  65  hydraulic lines  
           67  liquid tank  
           68  cylinder  
           69  piston  
           71  pump  
           72  pressure control valve  
           73  control unit  
           74 ,  75 ,  751 ,  752  electric lines  
           76 ,  761 ,  762  transducer  
           77  spring  
           631 ,  632 ,  651 ,  652  supply lines  
           641 ,  642  return lines  
           681 ,  682  chambers  
           621 ,  622  solenoid valves  
          M motor