Abstract:
An electrohydraulic unit including a hydraulic unit comprising an accommodating member that accommodates electrically actuatable valves and a hydraulic pump, an electric driving device for the pump, and a pressure fluid accumulator fed by the pump and including a media separating element and a sensor device including a receiving element for monitoring the position of the media separating element, and including an electronic unit for the electronic actuation of the valves and the driving device and for receiving electric signals of the sensor device. The sensor device is arranged in the accommodating member or in the electronic unit. An electrical connection is established between sensor device and electronic unit within the unit. This economizes mounting space and enables improved electrical connection.

Description:
TECHNICAL FIELD  
         [0001]    The present invention generally relates to an electrohydraulic control unit and more particularly relates to an electrohydraulic unit, in particular for slip-controlled motor vehicle brake systems.  
         BACKGROUND OF THE INVENTION  
         [0002]    An unit of this general type is disclosed in international publication WO 99/41125 and allows for the detection of gas or air disposed in the hydraulic part of the unit which may cause power loss of the system due to compressibility.  
           [0003]    German application DE 100 18 189 A1 discloses a pressure fluid accumulator for use in an electrohydraulic unit. The pressure fluid accumulator has a sensor device that is arranged in the gas chamber bounded by the media separating element in the housing and permits adapting a pressure/volume characteristic curve. The arrangement requires carefully sealing electric contact elements of the sensor device in relation to the ambience. The overall size of an electrohydraulic unit equipped with the prior art pressure fluid accumulator is considered as needing improvement.  
         BRIEF SUMMARY OF THE INVENTION  
         [0004]    An object of the present invention is to provide an electrohydraulic unit permitting a reduction of the available mounting space in a motor vehicle. Another objective is to reduce the overall size of the unit, in particular the high-pressure accumulator.  
           [0005]    According to the invention, this object is achieved in that the sensor device is arranged in the electronic unit or in the hydraulic unit, and in that an electrical connection is established between sensor device and electronic unit within the unit. The invention permits reducing the overall dimensions of the unit because the space available in the electronic unit or the hydraulic unit is utilized. This consequently reduces the necessary mounting space in the vehicle and, more particularly, reduces the mounting space needed for the high-pressure accumulator. The invention makes electrical contacting between sensor device and electronic unit possible that is protected against mechanical damage.  
           [0006]    According to a favorable embodiment of the invention, the electrical connection between electronic unit and sensor device is provided in parallel to a plug for the purpose of electrical supply of the driving device. This enables a uniform plane of assembly for joining driving device, pressure fluid accumulator, accommodating member and electronic unit.  
           [0007]    In another favorable embodiment of the invention, the electrical connection of the sensor device extends through the accommodating member. This protects the electrical connection, diminishing the influence of electromagnetic disturbances that act from outside.  
           [0008]    The space required for the sensor device is minimized when a sensing element of the sensor device is guided and arranged in a hydraulic connection between pressure fluid accumulator and accommodating member so as to be displaceable synchronously with the media separating element. This is because the absolutely necessary connection is also used to accommodate the sensing element. A low-cost arrangement of bores in the accommodating member is achieved when the hydraulic connection is provided in parallel to a bore for the plug. This applies in particular when the hydraulic connection is also provided in parallel to a pump bore.  
           [0009]    Advantageously, the sensing element is arranged in a sleeve that is pressure-tightly fastened to the accommodating member and extends into the area of the housing of the electronic unit. Said sleeve has a cup-shaped design, i.e. it is closed on one side, and quasi extends a hydraulic connection accepting a sensing element of the sensor device up to an inner space of the housing.  
           [0010]    In another embodiment of the invention, the sensor device includes a receiving element being arranged in a sleeve, the open end of said sleeve being pressure-tightly connected to the accommodating member, and with said sleeve defining the chamber of the pressure fluid accumulator.  
           [0011]    To effectively utilize the available space, the electric driving device and the pressure fluid accumulator are arranged on one side of the accommodating member and diagonally opposite each other. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a first embodiment of an electrohydraulic unit.  
         [0013]    [0013]FIG. 2 is a second embodiment of an electrohydraulic unit.  
         [0014]    [0014]FIG. 3 is a third embodiment of an electrohydraulic unit.  
         [0015]    [0015]FIG. 4 is a fourth embodiment of an electrohydraulic unit.  
         [0016]    [0016]FIG. 5 is a fifth embodiment of an electrohydraulic unit. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]    [0017]FIG. 1 is a greatly simplified view of an electrohydraulic unit  1  for hydraulic motor vehicle brake devices. Unit  1  comprises a hydraulic unit  2  with an accommodating member  3  for a hydraulic pump (not shown) comprising a pump bore and, preferably, pump pistons for feeding a pressure fluid accumulator  4  that is pressure-tightly attached to the accommodating member  3  and provided for the pressure supply of an electronically operated brake system of the brake-by-wire type. It is principally possible to use an internal geared wheel pump as the pump, what can contribute to further mounting space reduction. An electric driving device  5  is connected mechanically to the pump and fastened to a first side  6  of the accommodating member  3 . Pressure fluid accumulator  4  and driving device  5  are arranged paraxially relative to each other and diagonally opposite each other on side  6 . A plug  7  with electric conductors for the electrical supply of the driving device  5  extends through a bore  8  in the accommodating member  3  and, for the purpose of current supply, contacts a printed circuit board assembly  9  of an electronic unit  10 , whose housing  11  is attached to a second side  12  of the accommodating member  3  and along with said confines an inner space  13 . In addition, a bottom  89  is provided in housing  11  to separate the inner space  13  fluid-tightly from a hollow space  90  wherein basically the printed circuit board assembly  9  with electronic components is disposed. Bottom  89  is also used to fasten the printed circuit board assembly  9  to housing  11 . As FIG. 1 shows by way of example, one electromagnetic coil  14  (of principally several coils) of a hydraulic valve is connected to the printed circuit board assembly  9  by way of connecting wires  15 ,  16  and projects into the inner space  13  through which plug  7  extends. Connecting wires  15 ,  16  allow both an electrical connection and a quasi mechanically flexible coupling to the printed circuit board assembly  9 .  
         [0018]    Pressure fluid accumulator  4 , which is exemplarily configured as a piston-type accumulator but may basically also be designed as a diaphragm-type accumulator or metal pleated-bellows accumulator, comprises a media separating element  17  separating a first chamber  18  filled with compressed gas from a second chamber  19  filled with pressure fluid. The second chamber  19  is connectable to the pump by means of hydraulic connections  20 , one of which is only indicated in the drawing, or to wheel brakes by way of the interposed valves. The pressure fluid accumulator  4  can dispose of a valve  21  centrically arranged in a bottom area and preventing excessive evacuation by passing over into a closed position when a defined level in the accumulator is reached (FIG. 4). Preferably, valve  21  is controlled mechanically by the media separating element  17  approaching the bottom. Valve  21  can further be replaced by a valve element arranged annularly at the media separating element  80  (as shown in FIG. 5) or by an equally acting means without departing from the spirit of the invention.  
         [0019]    Adjacent to the bottom area is a substantially tubular socket  22  provided with an external thread that can be screwed into an internally threaded bore in the accommodating member  3 . The tubular socket  22  is further used to hydraulically connect chamber  19  to the connection  20 .  
         [0020]    The position of the media separating element  17  is monitored for the detection of compressibilities in the brake system. A sensor device  23  is provided for this purpose, the electric part of which is arranged in a recess in the accommodating member  3  in the embodiments according to FIGS. 1, 2,  4  and  5 . According to FIG. 5, the electric part of the sensor device is provided within the pressure fluid accumulator  88 , however, separated from chamber  19  by a sleeve  84 .  
         [0021]    As is shown in FIG. 1, the accommodating member  3  includes a blind-hole-type recess  24  devoid of pressure fluid, open towards side  12  and arranged in parallel to bore  8  for the plug  7 . An electric receiving element  25  of sensor device  23  is arranged in recess  24 . Receiving element  25  is provided at the end of a spacer  26  between printed circuit board arrangement  9  and recess  24 . Said spacer  26  is generally stiff and extends through the inner space  13  accepting electric conductors whose end  27  is electrically connected to the printed circuit board assembly  9 . A sensing element  28  of sensor device  23  has a rod-shaped design and is incorporated in a bore  91  of accommodating member  3  that is separated from recess  24  by a thin wall  92 . A spring element  29  is elastically preloaded between a step of socket  22  and a projection of sensing element  28  so that the latter is urged in the direction of the media separating element  17 . This renders the sensing element  28  together with the media separating element  17  displaceable relative to the receiving element  25  fixed in the accommodating member  3 . At the end of sensing element  28  close to the receiving element, there is a sensing member  30  cooperating with receiving element  25  for the generation of signals. Various principles may basically be used for the sensor device  23  so that e.g. a coil/armature assembly may be employed.  
         [0022]    As is illustrated, receiving element  25  along with spacer  26  and coil  14  is in electrical contact with and mechanically attached to the printed circuit board assembly  9  of the electronic unit  10 . For the final assembly, the entire electronic unit  10  with coil  14  suspended in an elastical and tolerance-compensating fashion and with receiving element  25  is slid in the direction of accommodating member  3  and fastened. Additionally, there is electrical contacting of interfaces (electric/magnetic plug). The driving device  5  is shifted in the direction of accommodating member  3  on side  6 . When the plug  7  is arranged at the driving device  5 , it is pushed through bore  8  into a recess in the area of the printed circuit board assembly  9  for electrical contacting. It is principally also possible to fix plug  7  at bottom  89 , as shown in FIG. 1, with the contacting with the printed circuit board assembly  9  being prefabricated. This achieves a plug connection close to the driving device in the area of an engine end plate (not shown) or in the area of a brush holding plate.  
         [0023]    The embodiment of FIG. 2 corresponds generally to the embodiment of FIG. 1, and equal reference numerals have been assigned to equal components. Different from FIG. 1, a pressure fluid accumulator  40  is not arranged along with a driving device  41  on a side  6  of the accommodating member  3  but is arranged on another side  46  displaced by 90°. Accordingly, a displacement axis  42  of sensing element  47  is offset by 90° relative to an axis  44  of plug  7 . Arranged in a recess  45  in the accommodating member  3  is a receiving element  43  of a sensor device  23  that corresponds mainly with FIG. 1. Receiving element  43  is provided at one end  27  of spacer  26  and deviated by 90° relative to said so that it can be inserted into recess  45 . A sensing element  47  is disposed in a hydraulic connection  20   b , which extends in parallel to a pump bore (not shown) and at right angles relative to an accommodating bore for the driving device  41  and at right angles relative to bore  8 . The assembly and electrical contacting of the construction units is as described relating to FIG. 1.  
         [0024]    According to FIG. 3, a receiving element  50  of a sensor device  51  is connected electrically to the printed circuit board assembly  9  by means of electric conductors  52 ,  53 . Receiving element  50  is e.g. an annular coil which, comparable with coil  54  of a valve, extends into a recess  55  within an electronic unit  56 . A housing  57  and side  12  of the accommodating member  3  confine recess  55 . No spacer is needed for the connection of receiving element  50 . A sensing element  59  of sensor device  51  has a longer design compared to FIG. 1 and extends completely through accommodating member  3  and at least partly through recess  55  so that signals for detecting the position of the media separating element  17  are generated due to translation of a component  60  of sensing element  59  in relation to receiving element  50 . Sensing element  59  is encompassed by pressure fluid as can be seen in FIG. 3. A bowl-shaped cylindrical sleeve  58  that is calked with an open end into the accommodating member  3  in a fluid-tight manner is used to seal the high-pressure area.  
         [0025]    An embodiment of FIG. 4 comprises a centrically arranged valve  21  in the bottom area of a media separating element  17  that includes a metal pleated bellows  76 . Because valve  21  has a compact body that is centrically arranged in the area of a tubular socket  71 , a sensor device  72  is not arranged centrically relative to the pressure fluid accumulator  70  as in FIG. 3 but quasi off-center in a recess  77  of the accommodating member  3 . Beside recess  77  another bore  74  is provided into which a bowl-shaped sleeve  78  is slid to accept a sensing element  73 . The bowl-shaped sleeve  78  is attached fluid-tightly to the pressure fluid accumulator  70  and opens with an open end into chamber  19 . Sleeve  78  disposes of a stop  93  for spring element  29 . The electrical connection of sensor device  72  is via a spacer  75  as described with respect to FIG. 1.  
         [0026]    The embodiment according to FIG. 5 includes a sensing element  81  fixed to a media separating element  80  and arranged within a pressure fluid accumulator  88 . Said media separating element  80  has a centrically arranged bowl  83 , open on one side and retracted in the direction of a first chamber  82 . Accommodating member  3  includes a bore  86  into which a sleeve  84  is pressure-tightly inserted to accept receiving element  85 . Sensing element  81  is slidable along with media separating element  80  in relation to receiving element  85  that is slid into sleeve  84 . Electric conductors  87  are used for the electrical connection, extending through sleeve  84  in the accommodating member  3  and through a recess in an electronic unit (not shown) up to a printed circuit board assembly (not shown). A spacer between printed circuit board assembly and receiving element  85  will bring about the necessary mechanical stability and simplification of the assembly.  
         [0027]    It is essential that the invention not only permits reduction of the overall dimensions but also a consequent division of labor during manufacture by making a distinction between the hydraulic/mechanical fabrication in the area of the accommodating member and the electric/mechanical equipment and fabrication in the area of the printed circuit board assembly. The subassemblies relating to electronic unit, accommodating member, driving device and pressure fluid accumulator may be assembled in a quasi plug-in type fashion. The electric connection system is arranged inside the unit and guided through the electronic unit and, optionally, through the accommodating member.  
       List of Reference Numerals  
       [0028]    [0028] 1  unit  
         [0029]    [0029] 2  hydraulic unit  
         [0030]    [0030] 3  accommodating member  
         [0031]    [0031] 4  pressure fluid accumulator  
         [0032]    [0032] 5  driving device  
         [0033]    [0033] 6  side  
         [0034]    [0034] 7  plug  
         [0035]    [0035] 8  bore  
         [0036]    [0036] 9  printed circuit board assembly  
         [0037]    [0037] 10  electronic unit  
         [0038]    [0038] 11  housing  
         [0039]    [0039] 12  side  
         [0040]    [0040] 13  inner space  
         [0041]    [0041] 14  coil  
         [0042]    [0042] 15  connecting wire  
         [0043]    [0043] 16  connecting wire  
         [0044]    [0044] 17  media separating element  
         [0045]    [0045] 18  chamber  
         [0046]    [0046] 19  chamber  
         [0047]    [0047] 20 , 20   b  connection  
         [0048]    [0048] 21  valve  
         [0049]    [0049] 22  socket  
         [0050]    [0050] 23  sensor device  
         [0051]    [0051] 24  recess  
         [0052]    [0052] 25  receiving element  
         [0053]    [0053] 26  spacer  
         [0054]    [0054] 27  end  
         [0055]    [0055] 28  sensing element  
         [0056]    [0056] 29  spring element  
         [0057]    [0057] 30  sensing member  
         [0058]    [0058] 40  pressure fluid accumulator  
         [0059]    [0059] 41  driving device  
         [0060]    [0060] 42  displacement axis  
         [0061]    [0061] 43  receiving element  
         [0062]    [0062] 44  axis  
         [0063]    [0063] 45  recess  
         [0064]    [0064] 46  side  
         [0065]    [0065] 47  sensing element  
         [0066]    [0066] 50  receiving element  
         [0067]    [0067] 51  sensor device  
         [0068]    [0068] 52  conductor  
         [0069]    [0069] 53  conductor  
         [0070]    [0070] 54  coil  
         [0071]    [0071] 55  recess  
         [0072]    [0072] 56  electronic unit  
         [0073]    [0073] 57  housing  
         [0074]    [0074] 58  sleeve  
         [0075]    [0075] 59  sensing element  
         [0076]    [0076] 70  pressure fluid accumulator  
         [0077]    [0077] 71  socket  
         [0078]    [0078] 72  sensor device  
         [0079]    [0079] 73  sensing element  
         [0080]    [0080] 74  bore  
         [0081]    [0081] 75  spacer  
         [0082]    [0082] 76  metal pleated bellows  
         [0083]    [0083] 77  recess  
         [0084]    [0084] 78  sleeve  
         [0085]    [0085] 80  media separating element  
         [0086]    [0086] 81  sensing element  
         [0087]    [0087] 82  chamber  
         [0088]    [0088] 83  bowl  
         [0089]    [0089] 84  sleeve  
         [0090]    [0090] 85  receiving element  
         [0091]    [0091] 86  bore  
         [0092]    [0092] 87  conductor  
         [0093]    [0093] 88  pressure fluid accumulator  
         [0094]    [0094] 89  bottom  
         [0095]    [0095] 90  hollow space  
         [0096]    [0096] 91  bore  
         [0097]    [0097] 92  wall  
         [0098]    [0098] 93  stop