Abstract:
The invention is based on a hydraulic unit for regulating the brake pressure in a vehicle brake system. Hydraulic units of such a type are the core component of an anti-lock vehicle brake system, of a drive slip vehicle brake system or of a vehicle brake system which regulates driving stability. The invention proposes a particularly advantageous arrangement of the required recesses in a housing block of a hydraulic unit. On account of the arrangement, the housing block can be reduced in terms of its dimensions, and can be produced with a lower weight and more simply in terms of production. For this purpose, according to the invention, the pressure fluid connection from one of the ports of the master brake cylinder to the suction side of one of the pump elements extends through the valve receptacle of the switching valve.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a 35 USC 371 application of PCT/EP 2008/058449 filed on Jul. 1, 2008. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is based on a hydraulic regulating the brake pressure in a vehicle brake system. 
     2. Description of the Prior Art 
     For safety reasons, recent models of motor vehicles are as a rule equipped with a vehicle brake system that has anti-lock, traction control, and/or vehicle control programs. The key element of such vehicle brake systems is a hydraulic unit disposed in the vehicle. The hydraulic unit is able to regulate the brake pressure at one or more wheels of the vehicle automatically as needed, with the aid of an electronic control unit, and thereby to stabilize the vehicle. The control unit to that end evaluates signals of sensors in the vehicle and triggers hydraulic components disposed on the hydraulic unit electronically accordingly. 
     In the prior art, a vehicle brake system with driving stability control is well known. See the brochure published by Robert Bosch GmbH, entitled “ Fahrstabilisierungssysteme ” [Driving Stability Systems], page 90,  FIG. 3 , which appeared in the “ Gelbe Reihe, Ausgabe  2004” [“Yellow Series, 2004 Edition”], ISBN 3-7782-2026-8. To aid in understanding the invention, the circuit diagram disclosed there is appended as  FIG. 1  and will now be described briefly: 
     The known vehicle brake system includes a driver-actuated master cylinder  10  for generating a brake force by muscle power. Connected to the master cylinder  10  are two separate brake circuits  12 ,  14 , each with two wheel brakes  16 ,  18 ;  20 ,  22 . For individual-wheel regulation of the brake pressure, there is a hydraulic unit  24 . It is connected between the master cylinder  10  and the wheel brakes  16 - 22  and has different hydraulic components. Each wheel brake is preceded by a respective inlet valve  26  and followed by a respective outlet valve  28 . The inlet valves  26  control a brake pressure buildup and the outlet valves  28  control a brake pressure reduction at the associated wheel brakes  16 - 22 . One pump  32  per brake circuit, which can be driven by an electric motor  30 , is capable of aspirating brake fluid out of the associated wheel brake  16 - 22  via one of the outlet valves  28  for brake fluid reduction and pumping it into the brake circuit  12 ,  14 . To enable making a fast brake pressure buildup, a low-pressure reservoir  34  is connected between the outlet valves  28  and the pump  32  of one brake circuit  12 ,  14 . Between the pump  32  and the low-pressure reservoir  34 , there is a check valve  36  that closes in the direction from the pump  32  to one of the wheel brakes  16 - 22 . This valve prevents the underpressure on the intake side of the pump  32  from being propagated into one of the wheel brakes  16 - 22 . 
     Each brake circuit  12 ,  14  furthermore has a high-pressure on-off valve  38  and a reversing valve  40 . The high-pressure on-off valve  38  makes it possible for the pump  32 , as needed, to aspirate necessary additional brake fluid directly from the master cylinder  10 . The reversing valve  40 , in the event of its actuation, can block a pressure fluid connection from the wheel brakes  16 ,  18 ;  20 ,  22  of a brake circuit  12 ,  14  with the master cylinder  10 . This is necessary in case brake pressure at one of the wheel brakes  16 - 22  is supposed to be automatically built up regardless of what the driver is asking for. This situation occurs during a traction control operation and/or driving stability control operation. 
     Moreover, check valves  42  are provided for controlling bypass conduits around the inlet valves  26  and the reversing valves  40 . Thus a reduction of brake pressure is made possible even if the inlet valves  26  are closed, and a buildup of brake pressure is made possible if the reversing valves  40  are closed, or in other words during a traction control or driving stability control operation that is taking place. Line connections are also embodied on the hydraulic unit  24  in order to put the aforementioned components  26 - 42  into hydraulic contact with one another. These line connections are represented in the schematic illustration by straight connecting lines. 
     The invention to be described below is based on embodying this known hydraulic circuit diagram in an especially space-saving way that is easy to achieve in the production of a housing block of a hydraulic unit  10 . 
     OBJECT OF THE INVENTION 
     The object of the invention is to propose a hydraulic unit which with regard to its outside dimensions is especially compact and whose housing block can be made more economically because of reduced mechanical machining effort and expense. 
     Because of its small dimensions, a hydraulic unit of the invention has a lower weight. Moreover, the proposed hydraulic unit makes highly dynamic brake pressure regulating operations possible, because the hydraulic line connections are especially short and have only few changes of course. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described in further detail below in conjunction with the drawings, in which: 
         FIG. 1  shows the hydraulic circuit diagram, well known from the prior art, of a vehicle brake system with driving stability control; 
         FIG. 2 , in a perspective view, shows the disposition of the recesses necessary for embodying this hydraulic circuit diagram, in a housing block, also already known from the prior art, of a hydraulic unit; and 
         FIG. 3  by comparison to  FIG. 2  shows a housing block with a disposition according to the invention of the requisite recesses. 
         FIGS. 2 and 3  are inverse views, that is, views which emphasize the recesses made on the housing block instead of the outlines of the housing block. Both views are on the same scale, so that the different size relationships of the resultant housing blocks are apparent. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 2  shows a housing block  50  of a hydraulic unit  10  ( FIG. 1 ) known from the prior art. This housing block  50  is formed by a solid metal plate, which is provided with many recesses by means of metal-cutting postmachining. A front side  52  of the housing block  50  is graduated at a right angle a single time over its entire width. A resultant step  54  divides the housing block  50  into a thicker part, located toward the top in  FIG. 2 , and by comparison a recessed, thinner part, disposed in the lower part of the drawing. A back side  56 , opposite the front side  52 , and a left and right side  58 ,  60  and a top and a bottom side  62 ,  64  of the housing block  50  are formed by plane-parallel faces. 
     In the lower part of the housing block  50 , there is a first recess  66 , which is intended for receiving a drive element, not shown. This first recess  66  is stepped multiple times from the outside inward in its diameter and ends in blind borelike fashion in the interior of the housing block  50 . For actuating the drive element, an electric motor, also not shown, can be secured from the outside to the lower part of the front side  52 . A supply to this electric motor is effected via contact elements, which can be passed through a through bore  68  above the recess  66  for the drive element to the back side  56  of the housing block  50 . This back side  56  serves the purpose of securing an electronic control unit (not shown), to which the contact elements can be connected, so that the electric motor is triggerable as needed. 
     Two pump elements are driven to a reciprocating stroke motion by the drive element. These pump elements are disposed on the housing block  50  in pump receptacles  70 ,  72 . These pump receptacles are formed by stepped bores, which begin at the two sides  58 ,  60  of the housing block  50  and discharge into the recess  66  for the drive element. These pump bores  70 ,  72  extend horizontally and coaxially to one another. 
     Two recesses discharge in the upper part of the housing block  50 , toward the front side  52 . They form the hydraulic connections  74 ,  76  of the hydraulic unit for the two brake circuits of an external master cylinder ( FIG. 1 ), for independent action on two brake circuits. Further hydraulic connections  78  are located on the top side  62  of the housing block  50 . These connections  78  are provided for hydraulic contacting of the wheel brakes ( FIG. 1 ;  16 - 22 ) of a vehicle. 
     Opposite the connections  78  of the wheel brakes, there are two recesses  80 ,  82  for low-pressure reservoirs on the bottom side  64  of the housing block  50 . Each of the low-pressure reservoirs is assigned to one of the brake circuits ( FIG. 1 ;  12 ,  14 ). Typically, known spring-loaded piston reservoirs are used as the low-pressure reservoirs. 
     Many identical valve receptacles  84 - 106  begin at the back side  56  of the housing block  50  and all end in blind borelike fashion in the interior of the housing block  50 . These valve receptacles  84 - 106  are intended for receiving the valve part of various kinds of solenoid valves (not shown). Coils of these solenoid valves are received in the electronic control unit and surround the portions of the valve parts that protrude past the back side  56  of the housing block  50 , once the control unit is mounted on that back side  56 . 
     The valve receptacles  84 - 106  are disposed in rows. There are in all four horizontally extending rows R 1 -R 4  of valve receptacles, and the rows are oriented parallel to one another and extend at different levels of the housing block  50 . 
     The first row R 1  oriented toward the top side  62  of the housing block  50  includes four valve receptacles  84 - 90 , which are intended for receiving the inlet valves. Located below this first row R 1  are the four valve receptacles  92 - 98  for the outlet valves, in a second row R 2 . The inlet and outlet valves are each associated in pairs with one of the wheel brakes. They serve, in the known manner, the purpose of pressure regulation. 
     A third row R 3  of valve receptacles is partly concealed in  FIG. 2  by the pump receptacles  70 ,  72 . This row includes only two valve receptacles  100 ,  102 , which are intended for the disposition of the high-pressure on-off valves of the vehicle brake system. Each brake circuit is equipped with one such high-pressure on-off valve. The high-pressure on-off valves control a hydraulic connection from the master cylinder ( FIG. 1 ;  10 ) to the intake side of the pump elements in the pump receptacles  70 ,  72 . A fourth row R 4 , oriented toward the bottom side  64  of the housing block  50 , likewise includes two valve receptacles  104 ,  106 , specifically for the so-called reversing valves of the vehicle brake system. Each of these is again present only once per brake circuit. These two valve receptacles are located closer to the sides  58 ,  60  of the housing block  50  than the valve receptacles  100 ,  102  of the high-pressure on-off valves of the third row R 3 , which are located closer to the center of the housing block  50 . The reversing valves as needed block an existing pressure fluid connection from the wheel brakes to the master cylinder. 
     The above-described elements  70 - 106 , with the exception of the recess  66  and through bore  68  for the drive element and for the contact elements of the electric motor, communicate hydraulically with one another through conduits that carry pressure fluid. For technical production reasons, these pressure fluid conduits are each oriented perpendicular to one of the outsides of the housing block  50  and thus may optionally meet at a right angle to one another in the interior of the housing block  50 . 
     Two inlet valve conduits  110 ,  112 , each beginning at a respective side  58 ,  60  of the housing block  50 , connect two side-by-side valve receptacles  84 ,  86 ;  88 ,  90 , respectively, for the inlet valves. The two inlet valve conduits  110 ,  112  are embodied as blind bores. They extend coaxially to one another in the horizontal direction and after their production are closed from the outside in pressure-fluid-tight fashion. As a rule, balls in the region of the orifice are press-fitted in for this purpose. 
     Two outlet valve conduits  114 ,  116 , which likewise begin at the respective sides  58 ,  60  of the housing block  50  and are embodied as horizontally extending blind bores, extend parallel and offset toward the back side  56  of the housing block  50  to the inlet valve conduits  110 ,  112  and each connect two of the valve receptacles  92 ,  94 ;  96 ,  98  of the outlet valves with one another. These outlet valve conduits  114 ,  116  are likewise closed from the outside after their production. 
     Two vertical conduits  118 ,  120  begin near the sides  58 ,  60  from the top side  62  of the housing block  50 . They each intersect one of the inlet valve conduits  110 ,  112  and each penetrate one of the pump receptacles  70 ,  72  and end each in one of the valve receptacles  104 ,  106  of the reversing valves. These vertical conduits  118 ,  120  are likewise closed from outside in a subsequent operation. 
     A first vertically extended connection conduit  122 ,  124  extends from the bottom of each recess  80 ,  82  for a low-pressure reservoir. This connection conduit penetrates the valve receptacle  100 ,  102  of the high-pressure on-off valves and ends in one of the cross conduits  126 ,  128 , which begin at the connections  74 ,  76  for a brake circuit of the master cylinder. Each connection conduit  122 ,  124  is put into contact with one of the valve receptacles  104 ,  106  of the reversing valves by a horizontal bore  130 ,  132  that is to be closed. 
     Moreover, there are hydraulic connections  134 ,  136  from the valve receptacles  100 ,  102  of the high-pressure on-off valves to the pump receptacles  70 ,  72 . These hydraulic connections are shown in dashed lines in  FIG. 1 , since they are hidden by the pump receptacles  70 ,  72 . 
     One second connection conduit each  138 ,  140 , beginning at the bottom of a respective one of the recesses  80 ,  82  for a low-pressure reservoir, established a direct pressure fluid connection between the recesses  80 ,  82  and one of the pump receptacles  70 ,  72 . Further connection conduits  142 ,  144  connect the recesses  80 ,  82  of a low-pressure reservoir directly with one of the two valve receptacles  94 ;  96  of the outlet valves. 
     Finally, each two valve receptacles  84 - 90 ;  92 - 98 , located one above the other, for an inlet valve and for an outlet valve are put into hydraulic contact with a respective connection  78  of a wheel brake. This purpose is served by coupling conduits  146 - 152 , which begin at the bottom of the connections  78  of the wheel brakes and end in one of the valve receptacles  92 - 98  of the outlet valves. In all, four such coupling conduits  146 - 152  are embodied on the housing block  50 . 
     In a vehicle brake system in accordance with the hydraulic circuit diagram of  FIG. 1 , each brake circuit can be divided into a so-called intake region and a system region. The intake region includes all the hydraulic components and pressure fluid connections that are to be associated with the intake side of an associated pump, while the system region includes all the components and pressure fluid connections that are disposed on the compression side of the associated pump. In  FIG. 2 , the recesses included in the intake region of a brake circuit are emphasized by a greater thickness of the lines representing them. The intake region of a brake circuit includes the respective connections  74 ,  76  of the master cylinder, the valve receptacle  100 ,  102  of the high-pressure on-off valve, and the pressure fluid conduits  122 ,  126  and connection  134 . 
     In the prior art described, this intake region leads from a connection  74 ,  76  of the master cylinder directly to a valve receptacle  100 ,  102  of a high-pressure on-off valve and from there directly onward to a pump receptacle  70 ,  72  and to one of the recesses  80 ,  82  of a low-pressure reservoir. The valve receptacles  104 ,  106  of the reversing valves are located on the far side of that intake region. They are each connected, by means of horizontal bores  130 ,  132  to be produced separately, to the intake region and are moreover supplied with pressure fluid. 
     Because of this arrangement, however, the establishment of a flow is prevented when the reversing valve is closed and the high-pressure on-off valve is open, in the region around the valve receptacles  104 ,  106  of the reversing valves. 
       FIG. 3  by comparison shows an advantageous disposition according to the invention of the recesses on a housing block  50 ′. This housing block  50 ′ can now be embodied in parallelepiped fashion with pairs of plane-parallel, ungraduated outer sides. Its outside dimensions are markedly smaller than those of the housing block  50  shown in  FIG. 2 . Consequently, the proposed housing block  50 ′ has a lesser weight. Moreover, its production requires markedly less time, since the production of the recesses necessitates fewer metal-cutting machining operations. In the ensuing description, the same reference numerals have been used for those recesses that correspond functionally to those of the housing block  50  of  FIG. 2 . 
     The recess  66  for the drive element, the pump receptacles  70 ,  72 , the connections  74 ,  76  for the master cylinder, and the connections  78  for the wheel brakes, as well as the recesses  80 ,  82  for the low-pressure reservoirs are located in the same relative positions as in the prior art of  FIG. 2 , so that repetition in this respect is unnecessary. The essential distinction of this housing block  50 ′ over that of  FIG. 2  is in the disposition and hydraulic contacting of the valve receptacles  84 - 106  on the back side  56 . 
     These valve receptacles  84 - 106  are again disposed in four parallel rows R 1 -R 4 , extending horizontally at different levels on the housing block  50 ′. However, the first row R 1 , oriented toward the top side  62  of the housing block  50 ′, now includes only the two valve receptacles  104 ,  106  of the reversing valves of a dual-circuit vehicle brake system. 
     Below it is a second row R 2  with a total of four valve receptacles  84 - 90 . These are staggered relative to the valve receptacles  104 ,  106  of the first row R 1 . These valve receptacles  84 - 90  receive the inlet valves of the vehicle brake system. 
     A third row R 3 , again comprising only two valve receptacles  100 ,  102 , is disposed slightly below the pump receptacles  70 ,  72  of this housing block  50 ′. These valve receptacles  100 ,  102  are intended for receiving the high-pressure on-off valves. With their inner end, they intersect the pump receptacles  70 ,  72  and as a result establish a pressure fluid connection, controllable by the high-pressure on-off valves, with the pump elements disposed in the pump receptacles. The valve receptacles  100  and  102  are staggered relative to the valve receptacles  84 - 90  of the second row R 2  and are located perpendicularly below the valve receptacles  104 ,  106  of the first row R 1 . 
     The fourth row R 4 , again comprising four valve receptacles  92 - 98 , which receive the outlet valves of the vehicle brake system, are located oriented toward the bottom side  64  of the housing block  50 ′. The valve receptacles  92 - 98  of the fourth row R 4  and those of the second row R 2  are located vertically one below the other. 
     The line connections for the hydraulic coupling of the receptacles, for the hydraulic components are made in this exemplary embodiment as well by means of bores extending perpendicular to one of the outer sides of the housing block  50 ′, so that they may optionally intersect at a right angle in the interior of the housing block  50 ′. 
     Two horizontally extending cross conduits  200 ,  202  that are coaxial with one another begin at the two sides  58 ,  60  of the housing block  50 ′ and end in the two valve receptacles  104 ,  106  of the reversing valves. Spaced apart below are two parallel-extending inlet valve bores  204 ,  206 . These again begin at the two sides  58 ,  60  of the housing block  50 ′ and each connect the respective two valve receptacles  84 ,  86 ;  88 ,  90  of the inlet valves of one brake circuit with one another. The inlet valve bores  204 ,  206  are embodied as blind bores and end in the respective inner valve receptacle  86 ;  88 . Both the two cross conduits  200 ,  202  and the two inlet valve bores  204 ,  206  are closed from the outside after their production. 
     For the production of a hydraulic connection of the cross conduits  200 ,  202  with the inlet valve bores  204 ,  206 , vertical conduits  208 ,  210  are provided. They are located close to the sides  58 ,  60  of the housing block  50 ′ and begin at the top side  62  of the housing block  50 ′. They discharge into a respective one of the pump receptacles  70 ,  72 . On their way there, the vertical conduits  208 ,  210  intersect both one of the cross conduits  200 ,  202  and one of the inlet valve conduits  204 ,  206 . The vertical conduits  208 ,  210  are likewise closed from the outside after their production. 
     A total of four blind bores  212 - 218  extend again in the vertical direction, but relative to the above-described vertical conduits  208 ,  210  they extend in a plane that is offset toward the back side  56  of the housing block  50 ′. These blind bores each begin at the bottom of the connections  78  of the wheel brakes; they then penetrate the valve receptacles  84 - 90  of the inlet valves, and end in the valve receptacles  92 - 98  of the outlet valves. 
     The valve receptacles  92 - 98  of the outlet valves of the wheel brakes are coupled, via short, vertically extending cross conduits  220 - 226 , with one of the recesses  80 ,  82  for a low-pressure reservoir on the bottom side  64  of the housing block  50   r . Besides the cross conduits  220 - 226 , a respective third vertical connecting conduit  228 ,  230  extends from the bottom of the recess  80 ,  82  of a low-pressure reservoir along a straight and vertical course to the valve receptacle  100 ,  102  of one of the high-pressure on-off valves. 
     Two vertical bores  232 ,  234 , made from the top side  62  into the housing block  50 ′ and closed from the outside after their production, intersect one of the connections  74 ,  76  of the master cylinder, and each penetrate one of the valve receptacles  104 ,  106  of the reversing valves and end in the one of the valve receptacles  100 ,  102  of the high-pressure on-off valves. Moreover, each of the vertical bores  232 ,  234  effects a connection with the respective pump receptacles  70 ,  72 . 
     If in this exemplary embodiment the intake regions of the two pumps are looked at (characterized by a widened line thickness of the applicable recesses), it can be seen that the pressure fluid connections from one of the connections  74 ,  76  of the master cylinder to one of the valve receptacles  100 ,  102  of the high-pressure on-off valves extend through one of the valve receptacles  104 ,  106  of the reversing valves. The effect of this is such that with the reversing valve closed and the high-pressure on-off valve open, flows of brake fluid that occur also cause flows in the regions of the valve receptacles  104 ,  106  of the reversing valves. This fundamental distinction from the subject of  FIG. 2  makes a housing block  50 ′ possible that has more-compact outer dimensions, a lower weight, and simpler metal-cutting machining. 
     The foregoing relates to the preferred exemplary embodiment of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.