Abstract:
The invention relates to an arrangement for fitting a brake assist device ( 10 ) in a motor vehicle having at least one fastening element ( 18, 20 ), which is disposed on and projects from a housing ( 12 ) of the brake assist device ( 10 ), wherein the at least one fastening element ( 18, 20 ) is provided with a retaining structure, by means of which it is fastenable to a vehicle chassis. The invention further provides that an adapter device ( 22 ), which is fastenable to the vehicle chassis so as to face the brake assist device ( 10 ) and which comprises at least one receiving opening ( 34, 36 ) for receiving the at least one fastening element ( 18, 20 ), wherein there is associated with the at least one receiving opening ( 34, 36 ) in each case a complementary retaining structure that interacts with the retaining structure on the at least one fastening element ( 18, 20 ).

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to an arrangement for fitting a brake assist device in a motor vehicle having at least one fastening element, which is disposed on and projects from a housing of the brake assist device, wherein the at least one fastening element is provided with a retaining structure, by means of which it is fastenable to a vehicle chassis.  
         [0002]     Because of constant endeavours to reduce the manufacturing costs of motor vehicles, in addition to a simplification of structural designs, consideration is meanwhile also being given to the need for assembly-friendly solutions. In this way the outlay, both in terms of labour and expenditure, for motor vehicle assembly may be reduced. Attention is being focussed in particular on considerably facilitating assembly work in the engine compartment or at other points of the motor vehicle that are difficult to access. This applies both to the original assembly and to repair or maintenance measures that are to be carried out at a later stage.  
         [0003]     In this connection, arrangements and methods of the initially described type are known from the background art. Thus, for example, the generic background art according to the document DE 38 04 850 A1 shows an arrangement, in which a brake booster may with low outlay be latched by detent means to a splashboard of a motor vehicle. For this purpose, on the splashboard at its side remote from the engine compartment detent sleeves are fitted, which are provided with resilient detent elements. Corresponding profiled bolts may be pushed into the detent sleeves. With this arrangement, which does admittedly facilitate assembly considerably, it is however necessary first to prepare the splashboard accordingly, thereby increasing as a whole the production outlay and hence the manufacturing costs. The arrangement of detent sleeves and resilient detent elements is moreover problematical in terms of maintenance because, in order to remove the brake assist device, assembly steps have to be carried out on both sides of the splashboard.  
         [0004]     The documents EP 0 262 006 A1 and DE 36 29 181 A1 also show arrangements, in which brake boosters may be fitted in an engine compartment of a vehicle with little assembly effort. This background art however also suffers from the problem that in each case the splashboard has to be provided with additional components at the side remote from the engine compartment, this considerably increasing the manufacturing outlay. And in the maintenance situation, in which for example the brake booster has to be removed, activity is necessary on both sides of the splashboard, thereby making the handling of such an arrangement laborious.  
         [0005]     Finally, from the document DE 42 31 787 A1 an arrangement from the background art is known, in which the splashboard itself is to be provided with profiled recesses, thereby adding considerably to the cost of its manufacture. Furthermore, in the maintenance situation the problem arises that, in order to remove the brake booster, assembly steps are necessary on both sides of the splashboard.  
         [0006]     The background art further includes U.S. Pat. No. 5,056,412 A, DE 38 04 850 A1, DE 36 29 181 A1, DE 689 03 745 T2.  
       BRIEF DESCRIPTION OF THE INVENTION  
       [0007]     Against this background, an object of the present invention is to provide an arrangement and a method for fitting a brake assist device in a motor vehicle, which while being of a simple and economical structural design allows simplified assembly.  
         [0008]     This object is achieved by an arrangement of the initially described type, wherein an adapter device is provided, which is fastenable to the vehicle chassis so as to face the brake assist device and which comprises at least one receiver for receiving the at least one fastening element, wherein there is associated with the at least one receiver in each case a complementary retaining structure that interacts with the retaining structure on the at least one fastening element.  
         [0009]     According to the invention, by the provision of an adapter device an interface is used, which may be already fitted on the splashboard prior to fitting thereof in the vehicle and together with the splashboard forms an assembly group. The adapter device has all of the arrangements needed for fitting the brake assist device. According to the invention there is therefore no need for costly production work to be carried out in advance on the splashboard. Rather, fastening openings that are in any case provided in a conventional splashboard may be used to fit the adapter device. In the course of further assembly of the vehicle, it is then merely necessary to carry out operations in the engine compartment i.e. at the side of the splashboard facing the engine compartment. This applies equally to the original assembly of the motor vehicle and to maintenance steps that are to be carried out at a later stage. Thus, by virtue of the invention, on the one hand, the manufacturing outlay of the individual components may be kept within limits, particularly because no special production measures have to be carried out on the splashboard, and, on the other hand, assembly is considerably facilitated.  
         [0010]     When in the context of this description of the invention reference is made to a “brake assist device”, this expression is to include cases where a pure brake force generator is fitted in the motor vehicle, i.e. an arrangement, in which the brake force exerted on the brake pedal by the driver is substantially lost and the brake force exerted on a master cylinder is generated “artificially”, for example by means of an electromagnetic arrangement. Equally, however, the expression “brake assist device” is also to include conventional brake boosters, in which the brake force exerted on the brake pedal by the driver is used for the actual brake force generation in the master cylinder and is optionally additionally boosted.  
         [0011]     A development of the invention provides that the adapter device is designed with fastening bores for fitting at the engine compartment side on a splashboard of the motor vehicle.  
         [0012]     According to the invention, it may further be provided that the adapter device has a receiving channel for receiving an actuating input portion of the brake assist device.  
         [0013]     This allows the brake assist device to be received securely and free of play. According to a development of the invention, it may however also be provided that the receiver for receiving one of the fastening elements and the receiving channel coincide, wherein the complementary retaining structure is formed around the receiving channel.  
         [0014]     According to a variant of the invention, it is provided that the at least one fastening element is formed by a profiled bolt, which is provided at its free end with a diameter contraction that forms the retaining structure, wherein the adapter device is provided with in each case one detent spring, which is fitted in the receiver and engages into the diameter contraction. In this connection, it may further be provided that the detent spring is locked in its associated receiver against axial movement. For example, the detent spring may be provided at one of its axial ends with a fixing ring, which rests against a stop in the adapter element and is fixed therein.  
         [0015]     In order further to facilitate assembly, a development of the invention in the context of the previously described variant of the invention provides that the profiled bolt is provided with a pilot pin or/and with a spreader ramp. The pilot pin allows easy introduction of the profiled bolt into the detent spring. As the profiled bolt is pushed further in, the detent spring is then spread open until it finally snaps into and engages behind the diameter contraction.  
         [0016]     In order to be able to guarantee a play-free abutment of adapter device and brake assist device, a preferably elastic buffer element is provided, which is disposed between the adapter device and the brake assist device. This buffer element may be for example an elastic rubber mat.  
         [0017]     An alternative variant of the invention provides that the at least one fastening element is formed by a headed bolt, which at its free end is provided with a detent head of enlarged diameter that forms the retaining structure, wherein the respective associated receiver of the adapter device is designed in the form of a bayonet groove for receiving and locking in each case one headed bolt. The headed bolt may for example have a T-shaped or mushroom-shaped profile.  
         [0018]     In a development of the bayonet catch, in the context of this variant of the invention it is further provided that the bayonet groove for fixing the brake assist device has in each case a ramp surface, which interacts with the headed bolt and onto which the headed bolt runs during fitting of the brake assist device on the adapter device. In this case, the ramp surface acts as a tightening bevel, so that brake assist device and adapter device are braced with one another. In this connection, reference is to be made again to the possibility of fitting a play-reducing rubber mat or the like between brake assist device and adapter device.  
         [0019]     In order to provide a clear assembly position, the invention in a development provides a stop face on the bayonet groove that provides a predefined relative position between brake assist device and adapter device. For example, in the region of this predefined relative position the ramp face may verge into a plateau surface, so that during assembly an assembly worker receives from a variation of the perceptible antagonistic forces a kind of tactile feedback for reaching the desired assembly position.  
         [0020]     A development of the invention provides that the fastening element is designed as a shank portion that projects from the brake assist device, and that the adapter device comprises a corresponding counterpart shank portion that is connectable to the shank portion. In this case, it is possible on the one hand that the shank portion is insertable into the counterpart shank portion, wherein the shank portion on its outer peripheral surface has the retaining structure, in particular a bayonet locking formation, and that the counterpart shank portion on its inner peripheral surface has the complementary retaining structure, in particular a complementary bayonet locking formation. As an alternative to this, it is however also possible that the counterpart shank portion is insertable into the shank portion, wherein the counterpart shank portion on its outer peripheral surface has the retaining structure, in particular a bayonet locking formation, and that the shank portion on its inner peripheral surface has the complementary retaining structure, in particular a complementary bayonet locking formation. In order moreover that the structure of the brake assist device need be modified only to a slight extent, a development of the invention provides that the fastening element, in particular the shank portion, is formed on a coupling element, which may be fitted as a separate component or as an assembly group on the brake assist device. Thus, it is possible to design both the coupling element and the adapter device specifically for the respective application and the respective installation situation and then fit them to the vehicle chassis and the brake assist device respectively.  
         [0021]     The clamping action achieved by the ramp surfaces is in itself sufficient to fix the brake assist device to the adapter device. To make such a fixing even more reliable, according to the invention it may be provided that on at least one component of adapter device and brake assist device a fixing element is provided for fixing the brake assist device to the adapter device in the predefined relative position. In an embodiment, it is in this case possible that the fixing element is formed by a fixing screw or by a fixing pin. As an alternative to this, it may however also be provided that the fixing element is formed by a high-friction surface that interacts with a corresponding counterpart surface on the respective other component of adapter device and brake assist device. During assembly, the two frictionally interacting surfaces are brought into mutual engagement and hold the brake assist device and the adapter device firmly together on reaching the assembly position. In the event of removal for maintenance purposes, the increased static friction forces then have to be overcome.  
         [0022]     A particularly reliable coherence, while keeping assembly simple, arises when the fixing element comprises a blade formation, which is provided with a number of locking blades that are aligned sloping at a setting angle in a locking direction. Given such a constructional variant of the invention, the locking blades may be deflected (pressed flat) more easily in assembly direction than in locking direction. Preferably the blade formation interacts with a corresponding detent tooth formation on the respective other component.  
         [0023]     The invention further relates to a method of fitting a brake assist device in a motor vehicle, having an arrangement of the previously described type, comprising the steps:  
         [0024]     A) fitting the adapter device at the engine compartment side on the vehicle chassis,  
         [0025]     B) introducing the at least one fastening element into the receiving opening associated therewith in the adapter device and  
         [0026]     C) fixing the brake assist device to the adapter device by bringing the retaining structure and the complementary retaining structure into engagement. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0027]     Various forms of construction of the invention are described below by way of example with reference to the accompanying drawings. The drawings show:  
         [0028]      FIG. 1 a  perspective view of a brake booster designed in accordance with the invention according to a first embodiment;  
         [0029]      FIG. 2 a  longitudinal section through an adapter device according to the invention according to a second embodiment;  
         [0030]      FIG. 3 a  sectional detail view illustrating the assembly position of brake booster and adapter device according to  FIGS. 1 and 2 ;  
         [0031]      FIG. 4 a  view of the second embodiment of a brake booster designed in accordance with the invention;  
         [0032]      FIG. 5 a  perspective view of an adapter device according to the invention according to the second embodiment;  
         [0033]     FIGS.  6  to  FIG. 8  detail views illustrating the mode of operation of the second embodiment;  
         [0034]      FIG. 9 a  view as in  FIG. 5  of a slightly modified form of construction of the adapter device;  
         [0035]      FIG. 10 a  view as in  FIG. 5  of an again slightly modified form of construction of the adapter device;  
         [0036]      FIGS. 11 and 12  detail views of a further form of construction according to the invention;  
         [0037]      FIG. 13 a  perspective view of a coupling element for retrofitting on a brake booster;  
         [0038]      FIG. 14  an adapter device matching the coupling element of  FIG. 13  for fitting to the vehicle chassis;  
         [0039]      FIG. 15  an alternative form of construction of a coupling element and  
         [0040]      FIG. 16  an alternative form of construction of the adapter device adapted to the coupling element according to  FIG. 15 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0041]     In  FIG. 1 a  brake booster designed in accordance with the invention is generally denoted by  10 . It comprises a housing  12  and an actuating input  14 , which extends from the housing  12  along a longitudinal axis A and is provided with an opening  15 , into which in the fitted state a force input element coupled to a brake pedal is introduced. A master cylinder  16  is moreover additionally connected to the housing  12  and coupled to a non-illustrated hydraulic system for generating a hydraulic brake pressure at likewise non-illustrated wheel brake units. It is further evident from  FIG. 1  that two profiled bolts  18  and  20  extend from the housing  12  parallel to the longitudinal axis A. These profiled bolts  18  and  20  are extensions of the tie bolts that are in any case provided in and pass through the brake booster. They are used to achieve easy and quick fitting of the brake force generator  10  in an engine compartment of a vehicle.  
         [0042]     For this purpose, in addition to the profiled bolts  18  and  20  an adapter device is also used, which is shown in  FIG. 2  and generally denoted there by  22 . The adapter device  22  comprises a circular-cylindrical basic body  24  adjoined by a flange  26 . Introduced into the flange  26  are a number of fastening bores  28 , which are used to fasten the adapter device  22  to a non-illustrated splashboard of a motor vehicle. More precisely, the flange  26  is flange-mounted by its end face  30  onto the non-illustrated splashboard. The basic body  24  has a central opening  32 , which likewise extends in the direction of the longitudinal axis A. The inside diameter d of this central opening  32  is adapted to the outside diameter D of the actuating input  14 .  
         [0043]     There are further introduced in the basic body  24  two axial bores  34  and  36 , which are designed with a diameter step near the free end of the basic body  24 . In these axial bores  34  and  36  detent springs  38  and  40  are inserted. The detent springs  38  and  40  each comprise a fastening ring  42  and  44 , with which they rest against the diameter step of the axial bores  34  and  36  and are fixed in the axial bores  34  and  36 , for example by press- or shrink fitting.  
         [0044]     For fitting the brake booster  10  in the engine compartment of a vehicle, first the adapter device  22  is screwed tightly to the splashboard in the previously described manner. This occurs preferentially prior to installation of the splashboard, so that the splashboard together with the adapter device  22  is fitted as an assembly group into the vehicle. The brake booster  10  is then fitted on the adapter device  22  by pushing the actuating input  14  into the central opening  32  of the adapter device  22 . The positioning of the profiled bolts  18  and  20  on the brake booster  10  corresponds to the positioning of the axial bores  34  and  36 , so that, when the actuating input  14  is pushed into the central opening  32  of the adapter device  22 , the profiled bolts  18  and  20  penetrate into the axial bores  34  and  36 .  
         [0045]     The already fitted state may be seen in the detail view according to  FIG. 3 . The profiled bolts  18  and  20  have on their front end a pilot pin  46 . This is adjoined in axial direction by a conical ramp portion  48 , which verges into a circular-cylindrical portion  50 . The circular-cylindrical portion  50  is in turn adjoined by a steeply inclined conical portion  52 , which leads to a diameter contraction  54 , i.e. to an undercut. The detent springs  38  and  40  have tapered spring arms  56 , which extend in a biased manner from a spring collar  58  in axial direction into the position shown in  FIG. 2 .  
         [0046]     While the profiled bolts  18  and  20  in the course of assembly are being pushed into the axial bores  34  and  36 , first the pilot pin  46  penetrates through the fastening ring  42  and/or  44  into the interior of the respective detent spring  38  and  40 . As soon as the inside of the spring arms  56  comes into contact with the conical portion  48 , the spring arms  56  are spread open. Finally, the free ends of the spread-open spring arms  56  slide across the circular-cylindrical portion  50  and snap into the undercut  54 . The housing  12  is therefore pulled against the adapter device  22  and firmly braced therewith. It should be noted that between housing  12  and adapter device  22  on their mutually opposing surfaces a rubber mat  60  is inserted, which holds the housing  12  and the adapter device  22  in close mutual abutment.  
         [0047]     By means of the arrangement shown in FIGS.  1  to  3  it is possible with a low constructional outlay to achieve a highly simplified fitting of the brake booster  10  on the vehicle splashboard constructed with the adapter device  22 .  
         [0048]     FIGS.  4  to  7  show a second embodiment of the arrangement according to the invention. To simplify the description and avoid repetition, for components of an identical type or an identical effect the same reference characters are used as for the description of FIGS.  1  to  3 , only prefixed by the number “1”.  
         [0049]      FIG. 4  shows a brake booster  110 , which corresponds substantially to the brake booster  10  of  FIG. 1 . Instead of the profiled bolts  18  and  20 , however, the brake booster  110  has headed bolts  118  and  120 . These comprise a detent head  166  and  168  and a shank  170  and  172 , wherein the diameter of the detent head  166  and  168  is considerably larger than the diameter of the shank  170  and  172 .  
         [0050]     The adapter device  122  according to  FIG. 5  also differs slightly from the adapter device  22  according to  FIG. 2 . For receiving the headed bolts  118  and  120 , bayonet grooves  176  and  178  are introduced into the end face  174  of the adapter device  122 . The bayonet grooves  176  and  178  have a receiving opening  180  and  182 , the diameter a of which is slightly larger than the outside diameter of the detent heads  166  and  168  of the headed bolts  118  and  120 . The bayonet grooves  176  and  178  further have in each case a locking slot  184  and  186 , which runs into the receiving opening  180  and  182  and has an inside width e that is slightly larger than the outside diameter of the shank  170  and  172 .  
         [0051]     FIGS.  6  to  8  show details of the coupling of brake booster  110  and adapter device  122  in accordance with the second embodiment of the invention.  FIG. 6  reveals that the locking slot  184  (like the locking slot  186 ) at its rear face remote from the end face  174  is provided with a ramp surface  188 , which is adjoined by a plateau surface  190 . It is further evident from  FIGS. 6 and 7  that the bayonet grooves  176  and  178  are delimited by a stop face  192 .  
         [0052]     For fitting the brake booster  110  on the adapter device  122  attached to a splashboard of the motor vehicle, first the actuating input  114  is introduced into the central opening  132 . The headed bolts  118  and  120  are then introduced by their detent heads  166  and  168  into the corresponding receiving openings  180  and  182  until the heads  166  and  168  have passed completely through them. In the course of assembly, the brake booster is then twisted in accordance with arrow P relative to the adapter device  122 . In this case, the detent heads  166  and  168  come into engagement with the ramp surface  188  and slide up it until they rest on the plateau surface  190 . Finally, the shank  170  and/or  172  comes into abutment with the stop face  192 .  
         [0053]     The two components, brake booster  110  and adapter device  122 , may therefore easily be fastened to and braced with one another in the style of a bayonet catch. A separation of these two components is effected simply by twisting in the opposite direction to the arrow P.  
         [0054]      FIG. 9  shows a development of the invention based on the representation according to  FIG. 5 . Although by means of the clamping action of the ramp surface  188  a strong coherence of brake booster  110  and adapter device  122  is already achieved,  FIG. 9  additionally shows the possibility of providing a fixing screw  194 , which is screwed into corresponding threaded bore  196 . In its screwed-in position, the fixing screw  194  prevents a relative movement between the brake booster  110  and the adapter device  122  by fixing the headed bolt received in the bayonet groove  178 .  
         [0055]     On the basis of the representation according to  FIG. 5 ,  FIG. 10  shows the possibility of fitting a friction element  198  on the inner peripheral surface of the central opening  132 . This friction element  198  interacts with the outer peripheral surface of the actuating input  114 , simultaneously increasing the sliding friction and in particular the static friction in the fitted state. The friction element  198  may be for example a rubber mat.  
         [0056]     As an alternative to this, according to the invention it is also possible, as shown in  FIGS. 11 and 12 , to fit a fixing element in the form of a blade formation  200  on the outer peripheral surface of the actuating input  114 . The blade formation  200  is shown to an enlarged scale in  FIG. 11 . It comprises a row of blades  202  aligned at a setting angle α relative to a base  204 . The blades  202  may be pressed down with a relatively low expenditure of force, wherein the setting angle is reduced. Setting the blades  202  up, on the other hand, calls for a relatively high expenditure of force, particularly because of the space needed for this. The blade formation  200  interacts preferably with a corresponding detent element, which is disposed on the inner peripheral surface of the central opening  132  and comprises a detent tooth arrangement corresponding to the blade formation. During the assembly of brake booster  110  and the adapter device  122 , the blade formation  200  is brought into engagement with the detent tooth arrangement, wherein the blade formation  200  is so aligned that this bringing-into-engagement is effected with a low expenditure of force. To separate the brake booster  110  and adapter device  122 , however, the blade formation  200  has to be brought out of engagement with the detent tooth arrangement by overcoming relatively high antagonistic forces. An accidental separation of brake booster  110  and adapter device  122  may therefore be avoided.  
         [0057]      FIGS. 13 and 14  show a further alternative according to the invention of an arrangement for fitting a brake booster on a vehicle chassis. For this purpose, a coupling element  210  is provided, which comprises a base plate  212 , from which a shank portion  214  extends. The base plate  212  has fastening bores  216 . The shank portion  214  is provided with a central through-opening  218 . The shank portion  214  is designed with radial tongues  220  on its outer periphery.  
         [0058]     The adapter device  222  according to  FIG. 14  likewise has fastening bores  228 . The adapter device  222  moreover has an annular projection  230 , which likewise has a central opening  232 . On the inner peripheral surface of the central opening, radial bayonet locking formations  234  are provided.  
         [0059]     As already described above, first the adapter device  222  is fitted on the vehicle chassis, for example to a splashboard of the vehicle. The coupling element  210  is further fitted subsequently on the brake booster. For this purpose, in each case the fastening bores  216  and  228  are used. The shank portion  214  may then be inserted in such a way into the central opening  232  that the tongues  220  engage between the bayonet locking formations  234 . In the course of further assembly, the brake booster plus the coupling element  210  is twisted in such a way relative to the adapter device  222  fastened on the vehicle chassis that the radial tongues  220  come into engagement with the bayonet locking formations  234  and so the brake booster provided with the coupling element  210  is held by means of the adapter device  222  on the vehicle chassis.  
         [0060]     It should be pointed out that the bayonet locking formations  234  are provided with undercut surfaces  236  that allow a secure locking of coupling element  210  and adapter device  222 . The bayonet locking formations  234  moreover also define a specific stop, so that the relative twisting may be effected only in a predetermined angular position.  
         [0061]      FIGS. 15 and 16  show an alternative form of construction to the embodiment according to  FIGS. 13 and 14 . It is apparent that the coupling element  310  and the adapter device  322  are designed in such a way that a shank portion  314  with radial tongues  320  is now provided on the adapter device  322 . On the other hand, a receiving ring  330  is provided on the coupling element  310 . The receiving ring  330  is connected by fastening ribs  338  in a fixed manner to the base plate  312 . The ring projection  330  also has on its inner peripheral surface  332  bayonet locking formations  334  that may be brought during assembly into engagement with the radial tongues  320  in order to lock the adapter device  322  to the coupling element  310  in an identical manner to that described above with reference to  FIGS. 13 and 14 .  
         [0062]     It goes without saying that in the fitted state the actuating input  14  or  114  of the brake booster extends through the central opening  218  or  318  of coupling element and/or adapter device, as has also already been described above with reference to FIGS.  1  to  12 . It should further be pointed out that in the fitted state in each case end faces  233  and  235  or  333  and  335  are in mutual abutment and hence fix a defined assembly position of the brake booster relative to the vehicle chassis in axial direction of the brake booster.  
         [0063]     The previously described embodiments of the invention demonstrate that a relatively quick and simple fitting of the brake booster on the adapter device already fitted on the splashboard is possible, wherein only assembly steps in the engine compartment, i.e. at the engine-compartment side of the splashboard, are required. The same applies to the removal of the brake booster in the maintenance situation.