Abstract:
An assembly includes a fluid reservoir and a master cylinder for a motor vehicle hydraulic brake system, the fluid reservoir being fastened to the master cylinder by a releasable connection and including at least one connection fitting, which is received in a corresponding connection aperture of the master cylinder. The fluid reservoir includes one or more components, which under a defined force applied to the fluid reservoir, allow a movement of at least one part of the fluid reservoir in the direction of the master cylinder.

Description:
This application is the U.S. National Phase of PCT International Application No. PCT/EP2010/050367, filed Jan. 14, 2010, which claims priority to German Patent Application No. 10 2009 000 770.9, filed Feb. 11, 2009, and German Patent Application No. 10 2010 000 813.3, filed Jan. 12, 2010, the contents of such applications being incorporated by reference herein. 
     FIELD OF THE INVENTION 
     The invention relates to an assembly comprising a fluid reservoir and a master cylinder for a motor vehicle hydraulic brake system. 
     BACKGROUND OF THE INVENTION 
     Such assemblies are generally known, for example from DE 100 47 325 A1, which is incorporated by reference, and as a rule are arranged just below an engine hood of the motor vehicle. In the fitted state the fluid reservoir of the assembly, in particular, is often situated directly beneath the engine hood. 
     The state of the art discloses safety devices for motor vehicles, in which, in the event of a vehicle impact with a correspondingly large degree of deformation, a so-called brake unit comprising a brake booster, a master cylinder and a fluid reservoir is pivoted away from the footwell so that the driver will not be injured. Such a safety device is disclosed, for example, by DE 103 26 952 A1, which is incorporated by reference. 
     The invention is concerned with the protection that a vehicle and its components afford to pedestrians. New provisions require that the front of the vehicle should comprise passive protection for pedestrians. In this context it is essential that the engine hood of the vehicle be capable of absorbing the impact energy of a body. This presupposes, however, that the engine hood is capable of deformation. Owing to the small overall space available in the engine compartment, the assembly comprising a master cylinder and a fluid reservoir cannot be arranged lower down in the engine compartment. Furthermore, the assembly and in particular the fluid reservoir must meet certain stability requirements, thereby making a deformation of the engine hood in the area of the assembly impossible. 
     SUMMARY OF THE INVENTION 
     The invention provides an assembly comprising a master cylinder and a fluid reservoir, which will satisfy the requirements relating to the protection of pedestrians. 
     According to aspects of the invention, the fluid reservoir comprises means, which under a defined force applied to the fluid reservoir allow a movement of at least a part of the fluid reservoir in the direction of the master cylinder. The assembly thereby meets the stability requirements, for example for the pressurized filling of the fluid reservoir with brake fluid, and in excess of a defined force, which is transmitted from the engine hood to the fluid reservoir in the event of an impact, allows a depression of the fluid reservoir, so that a deformation of the engine hood is possible and the impact energy can be absorbed. 
     According to an advantageous embodiment of the invention the means are provided between a base of the fluid reservoir and the master cylinder. The means can therefore easily be integrated into the assembly without taking up additional overall space. 
     The means are preferably formed onto the base of the fluid reservoir or are fastened to the base. This serves to ensure that the means will allow a depression of the fluid reservoir only in the event of a sufficiently predefined force. 
     According to an advantageous embodiment that is easy to produce, at least one web, which is formed onto the base of the fluid reservoir as crash element and which bends out of the way under a defined force applied to the fluid reservoir, is provided as means. 
     In an alternative advantageous embodiment at least one cylindrical projection, which is formed onto the base of the fluid reservoir as crash element and which bends out of the way under a defined force applied to the fluid reservoir, is provided as means. 
     According to a further advantageous embodiment that is easy to produce, a pin, which as crash element extends through two straps formed onto the base of the fluid reservoir and which breaks under a defined force applied to the fluid reservoir, may be provided as means. 
     In order to afford cost-effective manufacturing and ease of assembly, the pin here is made of plastics and comprises a head at a first end and expansion elements at a second end. 
     In another advantageous embodiment of the invention a cupped crash element, which can be inserted into guide grooves formed onto the base of the fluid reservoir and which bends out of the way under a defined force applied to the fluid reservoir, is provided as means. 
     An especially easy assembly is achieved in that a cupped crash element, which by means of sprung fastening lugs engages in undercuts formed onto the base of the fluid reservoir and which bends out of the way under a defined force applied to the fluid reservoir, is provided as means. 
     In order to achieve the predefined force with adequate stability of the cupped crash element, the cupped crash element may be provided from two different materials. 
     According to a further advantageous development of the invention the means are arranged in an indentation of the base of the fluid reservoir. 
     For this purpose the means may be provided in the form of two cylindrical sleeves of different diameter, which are connected together by means of one or more connecting webs and under a defined force applied to the fluid reservoir can be telescoped one inside the other through breaking of the connecting webs, the sleeve of larger diameter comprising formed-on projections to hold the sleeves in the indentation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features, advantages and possible applications of the invention will be apparent from the following description of exemplary embodiments and from reference to the drawing, which shows embodiments. In the drawing each highly schematic figure respectively shows: 
         FIG. 1  a section through a first exemplary embodiment of the assembly according to aspects of the invention; 
         FIG. 2  a section through a second exemplary embodiment of the assembly according aspects of to the invention; 
         FIGS. 3A and 3B  a section through third exemplary embodiments of the assembly according to aspects of the invention; 
         FIG. 4  a fourth exemplary embodiment of the assembly according to aspects of the invention; 
         FIG. 5  a section through the assembly according to  FIG. 4 ; 
         FIG. 6  a fifth exemplary embodiment of the assembly according to aspects of the invention partially in section; 
         FIG. 7  a further view of the fifth exemplary embodiment according to  FIG. 6 ; 
         FIG. 8  a section through the crash element of the fifth exemplary embodiment; 
         FIG. 9  a section though a crash element of a sixth exemplary embodiment; 
         FIG. 10  a section through a crash element of a seventh exemplary embodiment; 
         FIG. 11  a section through a crash element of an eighth exemplary embodiment; 
         FIG. 12  a section through a ninth exemplary embodiment of the assembly according to aspects of the invention; 
         FIG. 13  a longitudinal section through the crash element of the ninth exemplary embodiment according to  FIG. 12 ; 
         FIG. 14  the crash element of the ninth exemplary embodiment according to  FIG. 12  and 
         FIG. 15  a crash element of a tenth exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1 to 15  schematically show exemplary embodiments of an assembly according to aspects of the invention comprising a fluid reservoir  1  and a master cylinder  2  for a motor vehicle hydraulic brake system, the construction and working of which are basically known. Connection fittings (not shown) of the fluid reservoir  1  are received in corresponding connection apertures  3  of the master cylinder  2  after it has been fitted on the master cylinder  2  and connect hydraulic fluid chambers of the fluid reservoir  1  to pressure chambers of the master cylinder  2  in a known manner. 
     In order to configure the assembly in such a way that it satisfies the requirements with regard to the protection of pedestrians, the fluid reservoir  1  in the exemplary embodiments described below comprises means, which under a defined force applied to the fluid reservoir  1  allow a movement of at least a part of the fluid reservoir  1  in the direction of the master cylinder  2 . The assembly thereby meets the stability requirements, for example in the pressurized filling of the fluid reservoir  1  with brake fluid, and in excess of a defined force, which is transmitted from the engine hood to the fluid reservoir  1  in the event of an impact, allows a depression of the fluid reservoir  1  by a predefined distance x 2 , so that a deformation of the engine hood by a distance x 1  is possible and the impact energy can be absorbed. 
     Since the means described below provided between a base  4  of the fluid reservoir  1  and the master cylinder  2 , these can easily be integrated into the assembly without taking up additional overall space. 
       FIG. 1  shows a first exemplary embodiment. As can be seen from this, a web  5  that is easy to produce is formed onto the base  4  of the fluid reservoir  1  as crash element, which bends out of the way under a defined force acting on the fluid reservoir  1 , thereby allowing a depression of the fluid reservoir  1 . 
     A second exemplary embodiment, which is represented in  FIG. 2 , shows an L-shaped web  6  as crash element. The L-shape affords improved support for the web  6  on the master cylinder  2 . 
       FIG. 3A  shows a third exemplary embodiment. The crash element here comprises two webs  5  formed onto the base  4 .  FIG. 3B  shows that it is also possible to provide a cylindrical projection  7  as the crash element. 
       FIGS. 4 and 5  represent a fourth exemplary embodiment, which is likewise easy to produce. As can be seen from  FIG. 5  in particular, in this exemplary embodiment a pin  15 , which as crash element extends through two straps  16  formed onto the base  4  of the fluid reservoir  1  and which breaks under a defined force applied to the fluid reservoir  1 , is provided as means. 
     The pin  15  can be fitted from both sides and is preferably made from plastics. For captively securing the pin a first end of the pin comprises expansion elements  17  and a second end comprises a head  18 . The pin  15  is easy to produce and fit. 
     It will be clear from  FIG. 4  that if the pin  15  breaks the fluid reservoir  1  can be depressed by an amount x 2 . The dashed line l shows how far the engine hood of the vehicle has to be deformed, in order to allow absorption of the impact energy. 
       FIGS. 6 to 11  show further exemplary embodiments. 
     Thus  FIGS. 6 to 8 , for example, show a cupped crash element  19  of a fifth exemplary embodiment, which can be inserted into guide grooves  20  formed onto the base  4  of the fluid reservoir  1  and which bends out of the way under a defined force applied to the fluid reservoir  1 . As will be apparent particularly from  FIG. 8 , which shows the crash element  19 , this comprises a circumferential projection  26  for insertion into the guide grooves  20 . 
     Like the preceding exemplary embodiment,  FIGS. 9 and 10  show means in the form of cupped crash elements  21 ,  22 , which by means of sprung fastening lugs  23 ,  24  engage in undercuts  25  formed onto the base  4  of the fluid reservoir  1  and which bend out of the way under a defined force applied to the fluid reservoir  1 . 
       FIG. 11  shows an eighth exemplary embodiment. In contrast to the cupped crash elements  21 ,  22  the cylindrical crash element  27  shown in  FIG. 11  comprises inwardly directed sprung fastening elements  28 , which grip around a projection  29  formed onto the base  4  of the fluid reservoir  1 . 
     In order to achieve the predefined force with adequate stability, the cupped or cylindrical crash element  19 ,  21 ,  22 ,  27  may be provided from different materials. 
     A ninth exemplary embodiment is represented in  FIGS. 12 to 14 . It shows a crash element  8 , which comprises two cylindrical sleeves  9 ,  10  of different diameter. The two sleeves  9 ,  10  are connected by means of a circumferential connecting web  11 . The sleeve  9  is located by means of projections  12 , formed on the outside thereof, in an indentation  13  of the base  4  and is held therein. With its end the smaller sleeve  10  bears against the master cylinder  2 . Under a defined force acting on the fluid reservoir  1  the connecting web  11  breaks and the sleeves  9 ,  10  can be telescoped one inside the other by the distance a, that is to say the small sleeve  10  can subside into the larger sleeve  9  and the fluid reservoir  1  can be depressed by the distance x 2 . The distance a is advantageously greater than the distance x 2 . 
       FIG. 7  shows a crash element  9  of a tenth exemplary embodiment, which basically corresponds to the exemplary embodiment according to  FIGS. 12 to 14 . In contrast to these, multiple individual connecting webs  14  are provided for connecting the two sleeves  9 ,  10 . 
     LIST OF REFERENCE NUMERALS 
     
         
         
           
               1  fluid reservoir 
               2  master cylinder 
               3  connection aperture 
               4  base 
               5  web 
               6  web 
               7  web 
               8  crash element 
               9  sleeve 
               10  sleeve 
               11  connecting web 
               12  projection 
               13  indentation 
               14  connecting web 
               15  pin 
               16  strap 
               17  expansion element 
               18  head 
               19  crash element 
               20  guide groove 
               21  crash element 
               22  crash element 
               23  fastening lug 
               24  fastening lug 
               25  undercut 
               26  projection 
               27  crash element 
               28  fastening element 
               29  projection 
             a distance 
             l line 
             x 1  distance 
             x 2  distance