Abstract:
A hydraulic block for a hydraulic unit is configured to control the brake pressure in a slip-controlled vehicle brake system. Multiple pressure sensors are received in receptors that are defined by the hydraulic block and that are configured to place each of the pressure sensors in hydraulic contact with a respective brake circuit. The pressure sensors are configured to detect wheel brake pressures in the corresponding brake circuits. The hydraulic contact between the pressure sensors and the brake circuits is enabled by a common duct that includes a shut-off element configured to block a pressure medium connection between the brake circuits.

Description:
This application is a 35 U.S.C. §371 National Stage Application of PCT/EP2013/072091, filed on Oct. 22, 2013, which claims the benefit of priority to Serial No. DE 10 2012 223 172.2, filed on Dec. 14, 2012 in Germany, the disclosures of which are incorporated herein by reference in their entirety. 
     BACKGROUND 
     The disclosure proceeds from a hydraulic block for a hydraulic unit for controlling the brake pressure of a vehicle brake system with traction control. 
     DE 10 2007 047 124 A1, for example, discloses a hydraulic unit having such a hydraulic block. This hydraulic unit controls the brake pressure in two brakes circuits hydraulically separated from one another. For registering the brake pressure prevailing in the two brake circuits, sockets for multiple pressure sensors are formed on the hydraulic block, wherein at least one pressure sensor is assigned to each brake circuit. For production engineering reasons and design space reasons these sockets are in each case arranged at the internal, closed end of a fluid-ducting blind bore. The number of blind bores provided therefore corresponds to the number of sockets or pressure sensors. 
     Blind bores are produced by a metal cutting process, for example by boring, and thereby account for a significant proportion of the machining costs of a hydraulic block. Furthermore, only a limited block volume is available on the hydraulic block in which to accommodate these blind bores. A minimum interval between the blind bores is necessary in order to prevent the possibility of fluid under high pressure passing from the one brake circuit into the other brake circuit. The block volume, of necessity therefore, increases with the number of bores and sockets on a hydraulic block. The blind bores moreover open out onto the surroundings of the hydraulic block and in the area of their orifice must be sealed by a closing element, preferably in the form of a pressed-in ball. The number of closing elements increases the number of components, the assembly outlay and the weight of the hydraulic unit, along with the risk of an unacceptable leakage. 
     SUMMARY 
     A hydraulic block according to the disclosure, on the other hand, has the advantage that the hydraulic contact of the pressure sensors assigned to the different brake circuits is represented solely by one single outwardly led duct. A single duct is more easily accommodated between the already tightly packed openings and connections on the hydraulic block than multiple ducts and accordingly contributes less to the enlargement of the block volume. 
     From a production engineering standpoint the duct can be simply described as a blind bore which opens onto an outer side of the hydraulic block and is sealed in the orifice area by a closing element. A single duct can be produced more cost effectively, minimizes the number of apertures to be sealed on the hydraulic block and thereby reduces the risk of unwanted leaks during manufacture and in particular under operating conditions, compared to a hydraulic block having a plurality of such ducts. 
     Further advantages or advantages developments of the disclosure ensue from the claims, drawings, and/or from the description below. 
     A hydraulic contact of the duct with both brake circuits is possible by means of extremely short branch ducts and in a direct route, which minimizes pressure losses, idle fluid volumes and the hydraulic elasticity of the brake circuit. The branch ducts originate in existing sockets for solenoid valves and are sealed when fitting these solenoid valves. Additional closing elements can be dispensed with, saving further components, production outlay, block volume, weight and costs. 
     A hydraulic separation of the two brake circuits is achieved by a shut-off element anchored in the duct according to the disclosure. This element can be anchored, for example, by simply pressing it into the duct. The duct advantageously has a step, in the area of which the shut-off element is arranged. 
     In an advantageous development of the disclosure the shut-off element for separating the brake circuits and the closing element for outwardly sealing the duct are combined into one single component. This is particularly cost-effective to fit in just one operation. 
     Highly integrated hydraulic units affording hydraulic blocks of geometrically robust design, compact dimensions, low weight, ease of machining in manufacture and low assembly costs represent a significant competitive advantage, particularly in vehicle construction. 
     An exemplary embodiment of the disclosure is represented in the drawing and explained in detail in the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 and 2  each show perspective views of a hydraulic block according to the disclosure with sockets and ducts necessary for understanding the disclosure. 
       In  FIG. 1  the hydraulic block is viewed looking towards a front face, towards which the sockets provided for the solenoid valves open out. 
         FIG. 2  shows the view towards the rear face of the hydraulic block opposite the front face, which serves for the attachment of an electric motor for driving pump elements, which are fitted in corresponding sockets. 
         FIGS. 3 and 4  show different exemplary embodiments of shut-off and closing elements. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a hydraulic block  10 , particularly for a hydraulic unit for controlling the brake pressure in a vehicle brake system with traction control. This hydraulic block  10  is a cuboid formation which is preferably made from metal by continuous casting. Opening out onto the front face  12  of this hydraulic block  10  facing the viewer in  FIG. 1  are sockets  14   a ,  14   b ,  14   c , which are intended to accommodate solenoid valves. In total, twelve such sockets  14  are provided, for example, the longitudinal axes  16  of which are aligned parallel to one another and perpendicular to the front face  12  of the hydraulic block  10 . Four of these sockets  14  are arranged in each straight row  18  running horizontally, a total of three such rows  18   a ,  18   b ,  18   c  being formed parallel to one another at different heights on the hydraulic block  10 . The sockets  14   a  assigned to the first, top row  18   a  are intended to accommodate valves which control a pressure build-up in the wheel brakes of a vehicle brake system that can be connected to the hydraulic block  10 . Sockets  14   b , which are intended to accommodate valves which control a pressure reduction in these wheel brake of the vehicle brake system, are situated along an underlying second row  18   b . Below this in turn in the third, bottom row  18   c , sockets  14   c  are formed for valves which switch the vehicle brake system from the service braking mode into the traction control mode or which control a supply of fluid to pressure generators likewise provided on the hydraulic block  10 . 
     Sockets  14   d  for these pressure generators are situated between the second row  18   b  and the underlying third row  18   c , in an arrangement in which their longitudinal axes  16   d  run parallel to the three rows  18 , The sockets  14   d  assigned to the pressure generators each open out towards one of the opposite side faces  20  of the hydraulic block  10 . Of these side faces only the left-hand side face  20  of the hydraulic block  10  is visible in  FIG. 1 . 
     Above the sockets  14   d  for the pressure generators, sockets  14   e  are provided for damper elements. Their longitudinal axes  16   e  likewise run parallel to the three rows  18   a ,  18   b ,  18   c  of the sockets  14  of the valves and to the sockets  14   d  of the two pressure generators. These too open out towards opposite side faces  20  of the hydraulic block  10 . 
     Sockets  14   f  and  14   g  for a total of three pressure sensors are furthermore provided on the hydraulic block. The sockets  14   f  for a first pressure sensor and for a second pressure sensor are situated one perpendicularly above another on an imaginary central axis  22  running vertically through the hydraulic block  10 , which divides this into a left-hand and a right-hand part. The sockets  14  in the left-hand part and the sockets  14  in the right-hand part of the hydraulic block  10  are each connected to a hydraulic circuit by means of connecting ducts. The two hydraulic circuits are separated from one another, that is to say no fluid connection exists between the two hydraulic circuits, so that in the event of one brake circuit failing the other brake circuit remains serviceable. The socket  14   f  for the first pressure sensor is situated above the first row  18   a  of sockets  14   a  for valves and the socket  14   f  of the second pressure sensor lies between this first row  18   a  and the second row  18   b  of valve sockets. A socket  14   g  for the third pressure sensor is situated at the center of an imaginary square, the corners of which is formed by the longitudinal axes  16   b  and  16   c  of the sockets  14   b  and  14   c  of the valves in rows  18   b  and  18   c  in the left-hand part of the hydraulic block  10  in  FIG. 1 . 
     According to the disclosure the hydraulic contact of the sockets  14   f  for the first pressure sensor and the second pressure sensor is provided by a common duct  24 . This takes the form of a blind bore, which opens out towards an upper side  26  of the hydraulic block  10  visible in  FIG. 1 . Sockets  14   h  for the hydraulic connections of the wheel brakes also open out on this upper side  26 . In total four such sockets  14   h  are arranged side by side. 
     A longitudinal axis  16   f  of the blind bore forming the common duct  24  runs perpendicular to the rows  18  of sockets for the valves in the area of the central axis  22  of the hydraulic block  10 . The blind bore has one step in its inside diameter and is thereby subdivided into two bore portions  24   a  and  24   b  of differing inside diameters. The duct  24  has the bore portion  24   a  of larger diameter in the area where it opens out into the surroundings, whilst the bore portion  24   b , on the other hand, situated in the interior of the hydraulic block  10  and forming the closed end, is reduced in its inside diameter. The transition from the bore portion  24   a  of larger inside diameter to the bore portion  24   b  of smaller inside diameter may be designed as a right-angled step or as a taper, for example. 
       FIG. 2  shows the hydraulic block  10  described above from behind and thereby affords the viewer a view of its rear face  30 . Corresponding elements are identified by the same reference numerals in  FIG. 1  and  FIG. 2 .  FIG. 2  shows the hydraulic contact of the common duct  24  with the sockets  14   a ,  14   b  for the valves in rows  18   a ,  18   b  on the one hand and the hydraulic contact of the common duct  24  with the sockets  14   f  of the pressure sensors on the other. The latter contact ensues via first and second branch ducts  32   a  and  32   b , which run perpendicular to the front face  12  and the rear face  30  of the hydraulic block  10  and thereby connect the common duct  24  by the shortest possible route to the sockets  14   f  of the pressure sensors.  FIG. 2  furthermore shows third and fourth branch ducts  32   c ,  32   d , which are led in a straight line and at an angle of other than 90° towards the front face  12  and the rear face  30  of the hydraulic block  10 , and which each connect the common duct  24  to one of the laterally inner sockets  14   a  and  14   b  for valves. The third branch duct  32   c  establishes the connection of the socket  14   f  of the first pressure sensor to the socket  14   a  in the first row  18   a  in the right-hand part of the hydraulic block  10  in  FIG. 2 . This branch duct  32   a  opens into the bore portion  24   a  of the common duct  24  of larger inside diameter. The fourth branch duct  32   d , which establishes the hydraulic contact between the socket  14   f  of the second pressure sensor and the inner socket  14   b  of the valve in the left-hand part of the hydraulic block  2  in the second row  18   b , is connected to the bore portion  24   b  of the common duct  24  of smaller inside diameter. The sockets  14   a  and  14   b  provided with such contacts belong to different brake circuits. The two branch ducts  32   c ,  32   d  run in horizontal cross-sectional planes led on two different levels through the hydraulic block  10  shown. The selected inclination of the two angles of the branch ducts  32   c ,  32   d  can be seen to run in opposite directions. 
       FIGS. 3 and 4  show the common duct  24  for the contact of the sockets  14   f  for the first pressure sensor and the pressure sensor in longitudinal section. The bore portions  24   a  and  24   b  can be seen, with their different inside diameters and with the transition provided between them, which here takes the form of a taper, for example. The open end of the duct  24  is situated on the upper side  26  of the hydraulic block  10  indicated by hatching. The mouth of the fourth branch duct  34   d  is shown at the inner, closed end of the duct  24 . The third branch duct  32   c  arranged higher up on the hydraulic block  10  opens into the bore portion  24   a  of larger inside diameter from the opposite side. According to  FIG. 3  the external orifice of the duct is sealed by means of a closing element  40   a . A ball, which is pressed so that it is fluid-tight into the bore portion  24   b  in the area where the duct  24  opens out into the surroundings, is provided for this purpose. A shut-off element  40   b , which here also takes the form of a ball, is pressed into the bore portion  24   b  of smaller diameter shortly after the transition between the two bore portions  24   a ,  24   b . Instead of balls it is also possible, for example, to use cylindrical closing or shut-off elements (not shown) having diameters matched to the inside diameter of the associated bore portion  24   a ,  24   b.    
     The shut-off element  40   b  separates the fluid connection that otherwise exists between the two hydraulic circuits, so that the common duct  24  comprises a bore portion  24   a  connected to the one hydraulic circuit and a second bore portion  24   b  connected to the other hydraulic circuit. 
       FIG. 4  shows an alternative embodiment of a shut-off and closing element  42 , which is of a pin-shaped form and has a head  42   a  of a diameter matched to the bore portion  24   a . This head  42   a  is integrally formed with a shank  42   b  of a diameter matched to the bore portion  24   b . The length of the shank  42   b  here is selected so that this penetrates into the bore portion  24   b  of the duct  24  of smaller diameter and seals this as soon as the head  42   a  of the closing element  42  is pressed into the bore portion  24   a  of larger diameter and thereby seals the duct  24  off from the surroundings. 
     With a single pin-shaped shut-off and closing element  42  and a single pressing operation in a single duct  24  it is therefore possible both to separate the two hydraulic circuits from one another and to provide contacts for two pressure sensors with the two hydraulic circuits and finally to seal off the common duct  24  from the surroundings. This brings savings in overall space, weight, number of parts, production costs and assembly costs for the hydraulic block  10 . 
     Modifications or additions to the exemplary embodiments described are naturally feasible, without departing from the basic idea of the disclosure.