Abstract:
A hydraulic element, in particular for arranging in a pressure line between a master cylinder and a slave cylinder of a hydraulic clutch actuating arrangement, having a housing which has a master-cylinder-side hydraulic connection and a slave-cylinder-side hydraulic connection and which holds a valve arrangement, a simpler design is obtained in that the valve arrangement has two valve bodies which are mounted in a floating fashion in the housing and which can be moved relative to one another counter to the force of a spring.

Description:
This is a continuation of prior International Application PCT/DE2008/001438, filed Aug. 28, 2008, which claims priority to German Patent Application DE 10 2007 045 034.8, filed Sep. 20, 2007, the entire disclosures of which are hereby incorporated by reference herein. 
     The present invention relates to a hydraulic element, in particular, for the arrangement in a pressure line between a master cylinder and a slave cylinder of a hydraulic clutch operation system, with housing that features a master-cylinder-side hydraulic connection and a slave-cylinder-side hydraulic connection and accommodates a valve arrangement. 
    
    
     BACKGROUND 
     From DE 100 59 382, FIG. 6, in particular, a generic hydraulic element, a so-called anti-vibration unit is disclosed, which comprises two independent spring-loaded check valves. The opening pressure in both flow directions can be determined individually by spring preload for each direction. Such a part consists of many components and is complicated in assemblage. 
     Hydraulic elements in which valve function is formed by means of pinch valves for a flow direction. 
     Generic hydraulic elements known from the state of the art comprise a variety of individual parts by which the assemblage is complex. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a simple design for such a hydraulic element, in particular, to be able to manufacture this under the application of a few individual parts for instance or individual parts with little accuracy requirements. 
     The present invention provides a hydraulic element, in particular, for the arrangement in a pressure line between a master cylinder and a slave cylinder of a hydraulic clutch operation system, with housing that features one master-cylinder-side hydraulic connection as well as a slave-cylinder-side hydraulic connection and that accommodates its valve arrangement wherein the valve arrangement features two valve bodies that are supported inside the housing in a floating manner, and that can be displaced relative to one another against a spring force. 
     The valve arrangement comprises preferably an external valve body and an internal valve body, whereby the external valve body comprises a cup-shaped valve cup in which a tube-shaped section of the internal valve body is supported in a displaceable manner, wherein the valve cup and the tube-shaped section features at least a connection hole that can be brought to overlap depending on the position of the valve body relative to one another. 
     The outside valve body comprises preferably a valve head that features an axial hole and a radial hole connected with the latter. The valve head serves, in particular, the radial guide of the valve body in a hollow cylindrical section of the housing. 
     The external valve body and the internal valve body comprise preferably a means that prevents rotation in opposite directions of both bodies. This means prevents both bodies from rotating in opposite directions such that the holes cannot be brought to overlap. The means comprises preferably a finger of the internal valve body that is guided in an axial groove of the external valve body. Alternatively, this function could be assumed, e.g., also by the spring disposed between the two valve heads. 
     The internal valve body comprises preferably a valve head that forms a valve seat with the housing in an axial end position of the valve body. The valve seat seals the master-cylinder-side relative to the section located between the two valve heads, so that fluid can flow only via the axial hole in the internal valve body. With this, the damping filter has different flow resistances in the two flow directions. 
     The valve head of the internal valve body allows a gap preferably relative to a hollow-cylindrical section of the housing. The valve head fluid pushed out of the valve seat can flow through the gap. 
     The housing comprises preferably a clutch assembly on one side. The clutch assembly is mounted after the filter arrangement has been mounted. 
     The present invention also provides a hydraulic clutch operation system with a master cylinder, a slave cylinder and a pressure line connecting this pressure line, whereby a hydraulic element according to the invention is disposed in the pressure line. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following figures are exemplary embodiments of the invention illustrated, based on the attached drawings, as follows: 
         FIG. 1  shows a schematic illustration of a hydraulic system for operating a vehicle clutch. 
         FIG. 2  shows an exemplary embodiment of a damping filter according to the invention in a longitudinal section. 
         FIG. 3  shows the damping filter according to  FIG. 2  in Section A-A. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows as an example of a hydraulic power transmission system of a hydraulic clutch operation system  1  for a vehicle. The hydraulic clutch operation system  1  comprises a master cylinder  2  in a common manner that is connected hydraulically via a hydraulic pressure line  3  with a slave cylinder  4 . The slave cylinder  4 , for instance, can be formed as annular slave cylinder, a concentric slave cylinder, whereby an annular slave cylinder piston  5  is supported in annular cylinder housing. The annular slave cylinder  4  and the annular slave cylinder piston  5  again enclose an annular pressure chamber  16 . Upon actuation of the slave cylinder piston  5 , via a release bearing  6 , a disk spring  7  is activated in a common manner. The disk spring  7  serves to activate a vehicle clutch  17 . The latter comprises a pressure plate  8 , a counter pressure plate  9  and a clutch disk  10 . The disk spring  7  is preloaded such that it presses the pressure plate  8  onto a counter pressure plate  9  in the preload direction, and in the process, it clamps a clutch disk  10  that is connected non-rotatably with a transmission input shaft, between pressure plate  8  and counter pressure plate  9 . The pressure plate  8  and the counter pressure plate  9  are connected non-rotatably with a crankshaft of an internal combustion engine. When the slave cylinder  4  is pressurized, the disk spring  7  is moved via the slave cylinder piston  5  and the release bearing  6  that decrease the pressure in its preload direction, the pressure exerted by the pressure plate  8  towards the pressure plate  9 , and thus creating the frictional connection between the clutch disk  10  and pressure plate  8  or counter pressure plate  9 , is released. The master cylinder  2  comprises a master cylinder piston  11  that is activated by means of a clutch pedal  12  via a pressure rod  13 . Housing of the master cylinder  2  and the master cylinder piston  11  disposed movably inside enclose a pressure chamber  15 . A pressure-less tank  14  is hydraulically connected with the pressure chamber  15  in a pressure-less system, thus, the master cylinder piston  11  is extended to the furthest position outside the master cylinder  2 . 
     For a hydraulic clutch operation system  1 , as depicted in  FIG. 1 , vibrations are transmitted to the slave cylinder  4  from the combustion engine in particular from its crankshaft, via vehicle clutch  17  components. These vibrations are generated inside the pressure chamber of the slave cylinder  4  and thus inside the entire hydraulic system, comprising the pressure line  3  and the master cylinder  2 —pressure vibrations noticeable on the clutch pedal, as vibrations. To dampen these pressure vibrations (pressure pulsation) a hydraulic element  18 , hereinafter designated as a damping filter  18 , is disposed in the pressure line  3 . 
     The hydraulic clutch operation system according to  FIG. 1  is familiar of course. Instead of using a concentric release bearing as the slave cylinder  4 , also other hydraulic release bearings can be used, for instance, a lever release bearing that interacts with a slave cylinder. Likewise, instead of an operation of the master cylinder  2  with a clutch pedal  12 , an electrical actuator or the likes can be provided. Instead of exerting force on the disk spring to open as done here, the clutch can also be closed by exerting pressure (actively closed clutch). The embodiment of the master cylinder as well as that of the slave cylinder and likewise that of the clutch can be arbitrary; the prior depicted exemplary embodiment is only one of many possibilities. 
       FIG. 2  shows a damping filter  18  according to the invention, in a longitudinal section,  FIG. 3  shows the damping filter of  FIG. 2  in Section A-A. The damping filter  18  essentially comprises rotationally symmetrical housing  19  that on the one side comprises hydraulic plug  20  for connecting the damping filter  18  with a hydraulic socket of the pressure line  3  according to  FIG. 1 . The plug  20  forms a slave-cylinder-side hydraulic connection. On the side opposite the plug  20  of the housing  19 , a socket assembly  21  is fitted as a clutch assembly with socket  30  for plug connection in the housing  19 . The socket  30  forms a master-cylinder-side hydraulic connection. Obviously, plug  20  and socket  30  can be swapped or both connections can be formed as plug or as socket. The plug  20  and socket  30  of the socket assembly  21  can belong to the same hydraulic plug-socket connection; in this case, one could connect the plug  20  of a damping filter  18  with the socket  30  of another damping filter  18 , but they also belong to different types of hydraulic plug-socket connections. 
     The housing  19  comprises a hollow-cylindrical section  22  that on one side transforms into a cup-shaped bottom section  23  of the plug  20 , and on the other side, it transforms via a conical section  25  in a second hollow-cylindrical section  24  for accommodating the socket assembly  21 . The plug  20  features a through hole  26  that extends up to the hollow-cylindrical section  22 . 
     The plug  20  comprises a seal ring  27  as well as a ring groove  28 . Between the seal  27  and the ring groove  28  is a conical section  29  disposed, so that also the diameter of the plug  20  increases in this section. The socket group  21  features the receiving socket  30  that is formed such that it can accommodate a plug similar to that formed by plug  20 . Thus, a formed wire spring  31  engages with a corresponding ring groove  28  of the plug to be accommodated, which is introduced into the accommodating opening  30 . The socket group  21  carries in a ring groove  32  a seal ring  33  that seals the gap between the housing  19  and the socket group  21 . The socket group  21 , for instance, can be screwed together with the housing  19 , likewise, also a bayonet lock or a similar means can be provided or both parts can be glued or welded with one another or, for example, it can be friction-welded. A conical section  34  of the socket group  21  and a corresponding conical section  35  that adjoins to the second hollow-cylindrical section  24 , serve for axial positioning of the socket group  21  relative to the housing  19 . 
     Between the socket group  21  and the bottom  23  a valve arrangement  36  supported. The valve arrangement  36  comprises an external valve body  37  and an internal valve body  38  that are supported in the housing  19  in a floating manner. The external valve body  37  comprises essentially of a cup-shaped valve cup  39  that features a blind hole  40  with an internal diameter d 2 . The valve cup  39  transforms to its cup bottom side into a valve head  41 . The valve cup  39  has an external diameter D 2  that is obviously greater than the internal diameter d 2 . The valve head  41  has an external diameter D 3  that forms a clearance fit with the internal diameter of the hollow-cylindrical section  22 . The valve head  41  features an axial hole  42  that connects the through-hole  26 , via a radial hole  43 , with the hollow-cylindrical section  22 . The internal valve body  38  comprises a tube-shaped section  44  with an external diameter that with the internal diameter d 2  of the valve cup  39  a clearance fit. The tube-shaped section  44  is enclosed by the valve cup  39  and is supported in a sliding manner in this axial direction. The internal valve body  38  comprises furthermore a finger  45  that essentially extends in essentially parallel to the tube-shaped section  44  and meshes with an axial groove  46  that is provided in axial direction inside the valve cup  39 . The finger  45  together with the axial groove  46  provides non-rotational locking of the internal valve body  38  relative to the external valve body  37 . The internal valve body  38  comprises an axial hole  50  that extends in axial direction as well as a valve head  47  that is essentially conical in shape. The valve cup  39  of the external valve body  37  features a connection-hole  48 , the tube-shaped section  44  of the internal valve body  38  features a connection-hole  49 . The connection hole  48  transforms into a longitudinal groove  54 . When the connection holes  48  and  49  coincide at least partially, then the axial hole  42  is hydraulically connected with the axial hole  50 , so that fluid can flow through the damping filter  18 . Between the valve head  41  of the external valve body  37  and the valve head  47  of the internal valve body  38  is a spring  51  disposed that presses the two valve bodies  41 ,  47  and hence the internal valve body  38  and the external valve body  37  apart. 
     If fluid is pushed from the master cylinder side towards the slave cylinder, then on the circular surface of the valve head  47  designated with the double arrows A 1  of the internal valve body  38  a pressure that depends on the level of the pressure difference and on the size of the surface A 1  exerts a force in the direction of the arrow  52  on the internal valve body  38 . In this way, the internal valve body  38  is pressed against the force of the spring  51  in the direction of the arrow  52 . Depending on the level of the force resulting from the pressure difference, this movement occurs against the force of the spring  51  so far until the connection holes  48  and  49  coincide. Now fluid can flow from axial-hole  50  via the connection holes  48  and  49 , the remaining section of the hollow-cylindrical area  22 , the radial hole  43  and the axial hole  42  in the through-hole  26 . Between the external circumference of the valve head  47  of the internal valve body  38  and of the wall of the hollow-cylindrical section  22  a gap remains, through which fluid can flow as well. In the pressure-less state, as depicted in  FIG. 2 , the valve head  47  with the socket group  21  forms a valve seat  53  that practically does not allow fluid to flow-through. 
     When engaging the clutch while the pressure on the slave-cylinder-side is higher than that on the master cylinder side, a resultant surface area A 2  is effective; this is the surface determined by the internal diameter d 2  of the valve cup  39  and a pressure force depending on the area A 2  and on the pressure difference between master-cylinder-side and slave-cylinder-side in the direction opposite to the arrow  52 . The hydraulically effective surface area when the pressure on the slave-cylinder-side is higher than on the master-cylinder-side corresponds to the cross-section area of the blind hole  40 , since all other pressures forces on the external valve body cancel out, ultimately the pressure of the slave cylinder side acts via the hole  43  also in the section in which the spring  51  is disposed. If this pressure force exceeds the force of the spring  51 , then the external valve body  37  will be moved against the arrow  52  direction, so that the connection holes  48  and  49  coincide or at least partially coincide and release the flow—depending on the pressure difference of master-cylinder-side and slave-cylinder-side, and on the spring- 51  force. The connection holes  48  and  49  can also be brought to coincide in both flow directions depending on the positions of the valve bodies relative to one another. 
     The internal leakage between the master-cylinder-side and slave-cylinder-side is determined by the gap featured by the guide of the internal valve body  38  in the external valve body  37 . During vacuum pressure charge, the slave cylinder is evacuated via this gap. 
     REFERENCE SYMBOLS LIST 
     
         
           1  hydraulic clutch actuation 
           2  master cylinder 
           3  pressure line 
           4  slave cylinder 
           5  slave cylinder piston 
           6  release bearing 
           7  disc spring 
           8  pressure plate 
           9  counter-pressure plate 
           10  clutch disk 
           11  master cylinder piston 
           12  clutch pedals 
           13  push rod 
           14  pressure-less tank 
           15  pressure chamber 
           16  pressure chamber 
           17  vehicle clutch 
           18  damping filter 
           19  housing 
           20  plug 
           21  socket assembly 
           22  hollow cylindrical section 
           23  bottom section 
           24  second cylindrical section 
           25  conical section 
           26  through hole 
           27  seal ring 
           28  ring groove 
           29  conical section 
           30  mounting socket 
           31  formed wire spring 
           32  ring groove 
           33  seal 
           34  conical section 
           35  conical section 
           36  valve arrangement 
           37  external valve body 
           38  internal valve body 
           39  valve cup 
           40  blind hole 
           41  valve head 
           42  axial hole 
           43  radial hole 
           44  tube-shaped section 
           45  finger 
           46  axial groove 
           47  valve head 
           48  connection hole 
           49  connection hole 
           50  axial hole 
           51  spring 
           52  arrow 
           53  valve seat 
           54  longitudinal groove