Abstract:
A hydraulic section ( 1 ) for actuating a vehicle clutch having a master cylinder ( 3 ), a slave cylinder ( 2 ) and a hydraulic line ( 4 ) which connects both cylinders and is divided into two line sections by a ventilating device ( 5 ). The line sections of the hydraulic line which act as a siphon ( 4   a ) and a riser ( 4   b ) are guided together to said ventilating device ( 5 ), such that they are spaced apart from one another, in a chamber which is formed from at least one of these ends.

Description:
INCORPORATION BY REFERENCE 
     The following documents are incorporated herein by reference as if fully set forth: International Application No. PCT/DE2012/000390, filed Apr. 16, 2012; German Patent Application No. 102011100842.3, filed May 6, 2011; and German Patent Application No. 102011102814.9, filed May 30, 2011. 
     BACKGROUND 
     The invention relates to a hydraulic section for actuating a vehicle clutch. 
     During the actuation of a clutch pedal and therefore the pressure loading of a hydraulic fluid within a hydraulic section for clutch actuation, including essentially of a master cylinder which is connected to a clutch pedal, a slave cylinder, and a hydraulic line which connects said cylinders, it is known that air can accumulate in the end region of said hydraulic section, at the slave cylinder. Although this quantity is low, it has a negative effect on the disengagement travel at the slave cylinder in order to actuate the clutch. For this reason, as is known, the hydraulic line is laid so as to rise between the master cylinder and the slave cylinder, in a direction of the master cylinder, with the result that the introduced air is transported in the direction of the master cylinder in the form of one or more bubbles during the operation of the vehicle as a result of the buoyancy forces, and said air can escape into the reservoir via the snifting bore of said master cylinder. 
     It can occur, however, that the installation space does not allow a continuously rising course of the hydraulic line in the direction of the master cylinder to be realized. 
     SUMMARY 
     It is therefore the object of the invention to provide a hydraulic section for actuating a vehicle clutch, the ventilation of which is ensured via the master cylinder during operation, without the use of an additional component and without a continuously rising pathway of the hydraulic line in the direction of the master cylinder. 
     This object is achieved by way of a hydraulic section for actuating a vehicle clutch having one or more features of the invention. 
     According to one aspect of the invention, a hydraulic section for actuating a vehicle clutch having a master cylinder, a slave cylinder, and a hydraulic line which connects both cylinders is divided by a ventilating device into two line sections, said line sections of the hydraulic line which act as siphon and riser being guided together to said ventilating device, such that they are spaced apart from one another, in a chamber which is formed from at least one of these ends to said ventilating device. 
     In one advantageous refinement of the invention, the end of the siphon is configured as a connector of the ventilating device and the end of the riser is configured as a housing. However, it is also possible to configure the end of the siphon as a housing and the end of the riser as a siphon. 
     It is advantageous here that the end of that line section of the hydraulic line which acts as siphon opens with its hole laterally at the top into the chamber, and the lower inner wall of the end of the hole of that line section of the hydraulic line which acts as riser forms the lower boundary of the chamber in the radial direction. 
     It is advantageous here that there is a height difference between both holes, in order to make air buoyancy possible. 
     A further advantageous embodiment of the invention provides that the hole is routed further with a length in the housing and the internal diameter of the housing is widened radially at least over a region of said length. However, it is also possible that the hole is not routed further in the housing which is formed, but rather ends at the latter if it is, for example, a separate component with a housing, which separate component is incorporated into the hydraulic section. 
     Furthermore, it is advantageous that the radial widening of the internal diameter of the housing forms the chamber in the housing in the axial direction at least over said region. A further advantageous embodiment of the invention provides that the ventilating device is arranged in the hydraulic line at the highest point of the line section which comes from the slave cylinder. 
     The boundary of the chamber in the axial direction in the interior of the housing is formed advantageously by the end face of the connector which is introduced into the housing. 
     It is likewise advantageous to insert a ventilating device which is provided with connections as a separate component into the hydraulic section. 
     A further advantageous refinement of the invention provides that the hydraulic section is provided with a plurality of ventilating devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following text, the invention will be explained in greater detail using one exemplary embodiment and associated drawings, in which: 
         FIG. 1  is a diagrammatic illustration of one embodiment of a hydraulic section according to the invention for clutch actuation during a disengaging operation, 
         FIG. 2  shows the hydraulic section from  FIG. 1  during an engaging operation, 
         FIG. 3  is a diagrammatic illustration of a further embodiment of a hydraulic section according to the invention, and 
         FIG. 4  shows an enlarged ventilating device in section, which ventilating device is introduced into the hydraulic section according to  FIGS. 1 to 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIGS. 1 and 2  show a hydraulic section  1  for clutch actuation in two different operating positions. The hydraulic section  1  is formed essentially of a master cylinder  3  and a slave cylinder  2 . These cylinders are connected to one another via a hydraulic line  4 . As is apparent from  FIGS. 1 and 2 , the hydraulic line  4  is laid so as to rise in the direction of the slave cylinder  2 , it being possible for the air  6  which is present in the hydraulic line  4  to be transported to the master cylinder  3  via a line section which falls in the direction of the master cylinder  3 , and acts as a siphon  4   a  and is therefore called siphon  4   a , in which master cylinder  3  a ventilating device  5  which is introduced into the hydraulic line  4  at the highest point of the line section which comes from the slave cylinder  2  therefore prevents, at the start of the siphon  4   a , the air  6  which is situated in the hydraulic section  1  from moving back in the direction of the slave cylinder  2  during the disengaging operation. 
     Here, the line section which is situated upstream of the siphon  4   a  is called riser  4   b.    
     After the disengaging operation according to  FIG. 1 , the air  6  in the riser  4   b  upstream of the siphon  4   a  is displaced in the direction of the slave cylinder  2 . Since the time between the disengaging operation and the engaging operation is usually small and the air  6  is compressed greatly by the system pressure and therefore has considerably lower buoyancy forces, the air  6  in the riser  4   b  before the engaging operation ( FIG. 2 ) virtually does not rise in the riser  4   b  upstream of the siphon  4   a , as a result of which the following applies to the permissible volume in the region of the siphon  4   a:  
 
 V   siphon   &lt;V   swept,standard   −V   riser , where
 
     V swept,standard  is the swept volume which the slave cylinder  2  displaces during the disengaging operation, and 
     V riser  is the volume in the riser  4   b  between the siphon  4   a  and the air bubble  6  after the disengaging operation. 
     In this hydraulic section  1  according to the invention with an integrated ventilating device  5 , furthermore, V riser  is relatively small, that is to say the volume of the siphon  4   a  can be selected to be large. 
       FIG. 3  shows a further embodiment of a hydraulic section  1  according to the invention, in which any desired siphon heights and therefore components in the engine compartment can be overcome as a result of a plurality of siphons  4   a  with a respectively incorporated ventilating device  5  being connected behind one another. 
       FIG. 4  shows a sectional illustration of the ventilating device  5  which is incorporated into the hydraulic section  1 . This ventilating device  5  is formed essentially of a housing  10  which is configured as a bush which is molded or welded, for example, to the line section which acts as siphon  4   a , in order to ensure that it is seated in a positionally correct manner and a further anti-rotation safeguard can therefore be dispensed with. 
     A connector to the slave cylinder  2  can also be provided on the housing  10 . The housing  10  can then be attached directly to the slave cylinder  2 , by way of an anti-rotation safeguard with respect to the slave cylinder  2 . 
     The basic concept of the construction of said ventilating device  5  is to radially enlarge the region of the hydraulic line  4  at its end over a predefined region to such an extent that the hydraulic fluid flows through completely or partially below the air bubble  6  in the direction of the slave cylinder  2  when flowing through this space which is formed. This region of the hydraulic line therefore forms the actual ventilating device  5 , without the use of an additional housing or component. 
     However, the ventilating device  5  can also be configured as a separate component which is inserted between the two line sections. 
     As can be seen from  FIG. 4 , the housing  10  is constructed as follows: 
     On the end side of the housing  10 , that end of the hydraulic line  4  which is configured in the form of a connector  11  is inserted sealingly into said housing  10  to such an extent that a chamber  14  which is preferably of cylindrical configuration, just like the housing  10 , remains upstream of the connector  11  which is penetrated by a hole  12 . The inlet, in the form of a hole  13 , which comes from the slave cylinder  2  is situated at the opposite lower end of the chamber  14 . This is arranged in the housing  10  and dimensioned in such a way that the hole  12  of the connector  11  lies as high as possible above the hole  13  of the inlet of the slave cylinder  2 , that is to say the axis of symmetry of the hole  12  of the connector  11  and therefore of the inlet of the master cylinder  3  lies parallel to and spaced apart from the axis of symmetry of the hole of the inlet of the slave cylinder  2 . 
     Due to both holes  12 ,  13 , which are spaced apart from one another, of the inlets being guided together from the side and from below into the chamber  14 , the flow speed of the hydraulic fluid which flows from the master cylinder  3  to the slave cylinder  2  which is enriched with air is reduced. 
     At the same time, during this slowing of the flow speed, the air rises in the form of an air bubble  6  into an upper region of the chamber  14  and remains on the vertical wall there. As a result, the hydraulic fluid is displaced and “falls” below said air bubble  6 , as a result of which it passes via the hole  13  into the connector of the slave cylinder  2 . 
     If the fluid flows from the slave cylinder  2  to the master cylinder  3 , the moving hydraulic fluid column moves the air bubble  6  through the hole  12  of the connector  11 , or of the inlet of the master cylinder  3 , as a result of which said air bubble  6  can be transported further away from the slave cylinder  2  via the siphon  4   a  out of the hydraulic section  1  in a customary way. 
     LIST OF ELEMENTS 
     
         
         
           
               1  Hydraulic section 
               2  Slave cylinder 
               3  Master cylinder 
               4  Hydraulic line 
               4   a  Line section/siphon 
               4   b  Line section/riser 
               5  Ventilating device 
               6  Air bubble 
               10  Housing 
               11  Connector 
               12  Hole 
               13  Hole 
               13   a  Inner wall 
               14  Chamber 
               15  Region 
             A Region 
             L Length