Abstract:
The invention relates to an integral brake for a motorbike. The integral brake is designed in such a way that if the footbrake lever or the handbrake lever is additionally activated after the footbrake lever or the handbrake lever is already activated, an optimum distribution—corresponding to the aimed-at increased deceleration of the motorbike—of the braking forces applied to the front and rear wheels is brought about without influencing the pressure prevailing in the handbrake cylinder.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is based on German Application No. 10 2004 051 119.5, filed Oct. 20, 2004, which is hereby incorporated herein in its entirety. 
   FIELD OF THE INVENTION 
   The invention relates to an integral brake for a motorbike. Such an integral brake can be used, by optionally activating the handbrake lever or the footbrake lever, to activate both the hydraulic brake devices assigned to the front wheel and the hydraulic brake devices assigned to the rear wheel. In order to bring about optimum distribution of the braking forces occurring at the front and rear wheels, the activation force of the individual brake devices is determined by an electronic control unit. After the braking process has been initiated using the handbrake lever, it is possible to generate an additional braking force by activating the footbrake lever, or vice versa. Since this additional braking force which is generated using the footbrake lever or using the handbrake lever is superimposed on the braking force which has already been generated using the handbrake lever or using the footbrake lever, it is necessary to re-adjust the activation forces of the brake devices acting on the front and rear wheels in order to obtain a desired braking force distribution again. 
   BACKGROUND OF THE INVENTION 
   JP 2000071963 A describes such an integral brake for a motorbike. As a result of the hydraulic connection of the brake components, reactions relating to the activation path of the brake levers occur during the simultaneous activation of the two brake devices. When only one brake device is activated using the handbrake lever or footbrake lever, the pressure/volume identifier of the brake system determines the activation path/braking pressure (deceleration) ratio. If the second brake lever is then additionally activated, the pressure/volume identifier of the second brake circuit changes considerably since braking pressure has already been increased by the integral effect using the pressure modulator in the second brake circuit. The second brake lever is “hard”, and the activation path/braking pressure ratio has changed. If both brake levers are activated and if the braking pressure in one brake circuit is increased, the lever position of the second brake lever changes even if the braking pressure is also increased in this brake circuit (depending on the distribution of braking force) and brake fluid volume is thus displaced. These feedback reactions to the brake lever which is respectively activated first have a disruptive effect on the rider. This applies in particular to the reaction of the handbrake lever because the hand is significantly more sensitive than the foot. 
   SUMMARY OF THE INVENTION 
   The invention is based on the object of improving this known integral brake to the effect that when both brake levers are activated the pressure prevailing in the handbrake cylinder remains unaffected so that there is no feedback at the handbrake lever. 
   The means of achieving this object, and expedient developments of the invention, emerge from the claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Two exemplary embodiments of the invention are illustrated schematically in the drawings and will be explained in more detail below. In the drawings: 
       FIG. 1  shows a schematic illustration of a first embodiment of an integral brake for a motorbike, 
       FIG. 2  is a diagram illustrating the relationship between the hydraulic pressure generated using the handbrake lever and the deceleration factor which is achieved as a result of this, 
       FIG. 3  is a diagram illustrating the relationship between the hydraulic pressure generated using the footbrake lever and the deceleration factor which is achieved as a result of this, 
       FIG. 4  is a diagram illustrating the distribution of the braking force to the front and rear wheels, and 
       FIG. 5  shows a second exemplary embodiment of an integral brake for a motorbike. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The integral brake, illustrated schematically in  FIG. 1 , for a motorbike comprises a handbrake lever  1  for activating a first hydraulic brake device which acts on the front wheel, and a footbrake lever  2  for activating a second hydraulic brake device which acts on the rear wheel, and a third brake device which acts on the front wheel. While only one brake disk  3  is attached to the rear wheel of the motorbike, two brake disks  3  are attached to the front wheel. Each of these brake disks  3  is assigned a brake caliper in which one or more pressure chambers are formed. The handbrake lever  1  acts on a handbrake cylinder  4  which is connected via a line  5  to the two brake calipers which are assigned to the front wheel. For reasons of symmetry, three pressure chambers are formed in each of the two front brake calipers, and the line  5  is connected to the two outermost pressure chambers. A pressure sensor  30  which measures the pressure generated using the handbrake cylinder  4  and a pressure sensor  6  which measures the activation pressure of the front hydraulic brake device are arranged in the line  5 . A rotational speed sensor  12  measures the rotational speed of the front wheel. A pressure modulator which reduces the pressure prevailing in a line  5  as soon as the front wheel locks is integrated into the line  5 . This pressure modulator comprises an inlet valve  7  which is arranged in the line  5 , and a line  8  which bypasses the inlet valve  7 , with an outlet valve  9  and a pump  10  being arranged in the bypass line  8 . The pump  10  has a drive connection to an electric motor  11 . 
   The footbrake lever  2  is coupled to a footbrake cylinder  13  which is connected via a line  14  to the hydraulic brake device which acts on the rear wheel. To be more precise, the line  14  is connected to the pressure chamber or chambers which are formed in the brake caliper assigned to the rear brake disk  3 . A pressure sensor  15  which measures the pressure generated using the footbrake cylinder  13  and a pressure sensor  16  which measures the activation pressure of the rear hydraulic brake device are arranged in the line  14 . A pressure modulator which is of basically similar design to the pressure modulator which is integrated into the line  5  is integrated into the line  14 . This pressure modulator comprises an inlet valve  17  which is arranged in the line  14  and a line  18  which bypasses the latter and in which an outlet valve  19  and a pump  20  are arranged. The pump  20  has a drive connection to the electric motor  11 . The pump  20  is connected to the line  14  via an intake line  21 . A suction valve  22  is arranged in the intake line  21 , and a parting valve  23  is arranged in the line  14 , downstream of the junction with the intake line  21 . A line  24  is connected to the line  14  in the region between the parting valve  23  and the inlet valve  17 . The line  24  is connected to the central pressure chamber of each of the two brake calipers which are attached to the front wheel. A pressure sensor  25  which measures the activation pressure of the brake device which acts on the front brake disks  3  is arranged in the line  24 . In addition, a pressure modulator is integrated into the line  24 . This pressure modulator comprises an inlet valve  26  which is arranged in the line  24  and a line  27  which bypasses it and in which an outlet valve  28  is arranged and which is connected to the bypass line  18  on the suction side of the pump  20 . 
   A rotational speed sensor  29  is also assigned to the rear wheel, in a similar way to the front wheel. 
   The two rotational speed sensors  12  and  29 , the four pressure sensors  6 ,  15 ,  16  and  25 , the electric motor  11 , the solenoid valves  7 ,  9 ,  17 ,  19 ,  26 ,  28  of the three pressure modulators, and the intake valve  22  and parting valve  23  are connected to an electronic control unit (not shown). 
   A certain distribution of the braking force applied to the front and rear wheels is necessary to decelerate the vehicle in an optimum way. 
   This ideal distribution of braking force is illustrated in the diagram according to  FIG. 4 . As the braking force at the front wheel increases, the optimum braking force also rises at the rear wheel before dropping again after a maximum value has been reached. If the braking force which is applied to the front wheel is so large that the rear wheel begins to lift off, the braking force which is applied to the rear wheel then drops to zero. In addition, a group of straight lines which correspond to a specific delay value is shown in the diagram according to  FIG. 4 . The point of intersection of a straight line with the curve for the ideal braking force distribution yields the optimum front or rear braking force for the respective deceleration. 
   The pressure generated in the handbrake cylinder  4  or in the footbrake cylinder  13  using the handbrake lever  1  or, respectively, the footbrake lever  2  corresponds to a specific deceleration factor which rises linearly with the pressure, as shown in  FIGS. 2 and 3 . If braking is carried out using the handbrake lever  1  or footbrake lever  2 , it is then possible to use the pressure measured by the pressure sensors  30  and  15  as the basis for determining the deceleration factor which corresponds to said pressure and which reflects the deceleration desired by the rider. From the diagram according to  FIG. 4 , it is possible to determine the braking forces which are associated with this deceleration factor and which are to be applied for optimum distribution to the front and rear wheels of the motorbike. The diagrams according to  FIGS. 2 ,  3  and  4  are stored in the electronic control device of the integral brake. 
   The method of operation of the integral brake which is illustrated in the drawing will be explained below. 
   Firstly, the case in which the motorbike is braked solely by activating the handbrake lever will be considered. Pressure is increased in the line  5  by activating the handbrake lever  1 . On the basis of this pressure p v1  determined by the pressure sensor  30  it is possible to determine the associated deceleration factor a v1  from the diagram according to  FIG. 2 . On the basis of this deceleration factor a v1  it is then possible to determine, from the diagram according to  FIG. 4 , the optimum braking force which is to be applied to the rear wheel for such deceleration, and thus the corresponding braking pressure. As already mentioned, the pressure with which the brake device assigned to the rear wheel needs to be activated to achieve an optimum braking force distribution is determined by the electronic control unit. The electric motor  11  is then started in order to drive the pump  20 . In this context, the suction valve  22  and the inlet valve  17  are opened while the parting valve  23  and the outlet valve  19  are closed. For this reason, a pressure is increased in the line  14 . If the pressure measured by the pressure sensor  19  arranged in this line corresponds to the pressure determined by the electronic control unit, the pump  20  is switched off. The force which corresponds to an optimum distribution of the braking force applied to the front and rear wheels is therefore applied to the brake calipers which are assigned to the two front brake disks  3  and the rear brake disk  3 . If the front or rear wheel happens to lock, the activation pressure prevailing in the line  5  or  14  is reduced in a known fashion by means of the pump  10  or  20 . 
   In the braking process described above, the inlet valve  26  and outlet valve  28  are closed. However, in order to reduce the force which is to be applied to the handbrake lever  1 , the corresponding pressure modulator can also be activated, i.e. the inlet valve  26  is opened in order to support, via the line  24 , the brake calipers which are assigned to the front brake disks. In this case, the pressures which are measured by the pressure sensors  6  and  25  must be added and the associated deceleration factor must be determined from the diagram according to  FIG. 2  on the basis of the corresponding sum value. The activation pressure which is necessary for optimum braking force distribution in the line  14  can then be determined for the brake device assigned to the rear wheel, from the diagram according to  FIG. 4 . 
   If the footbrake lever  2  alone is activated, a pressure p h1  is increased in the lines  14  and  24 . In an analogous fashion, pressure determined by the pressure sensor  15  is used as the basis for determining the corresponding deceleration factor a h1  by means of the diagram according to  FIG. 3 , and this deceleration factor can be used as the basis for determining, by means of  FIG. 4 , the corresponding optimum braking force to be applied to the front wheel. If this pressure is above the pressure generated by the rider, the necessary, additional pressure is increased in the line  24 . For this purpose, the pump  20  is driven by means of the electric motor  11 , the suction valve  22  is opened and the parting valve  23  is closed. If the pressure, measured by the pressure sensor  25 , in the line  24  reaches the predetermined value, the inlet valve  26  can be closed and the pump  20  is switched off. If the activation pressure prevailing in the line  14  is lower than the activation pressure prevailing in the line  24 , pressure must be correspondingly reduced using the pump  20  by closing the inlet valve  17  and opening the outlet valve  19 . In an analogous fashion, the pressure in the lines  14  and  24  can be reduced if the front wheel and/or the rear wheel locks. 
   If the footbrake lever  2  is additionally activated using the handbrake lever  1  after a braking process has been initiated, an additional pressure p h2  is increased by the footbrake cylinder  13 , said pressure p h2  being measured with the pressure sensor  15 . By means of  FIG. 3 , the deceleration factor a h2  which is associated with the measured pressure p h2  is determined and added to the deceleration factor a v1  which is defined by the activation pressure p v1  prevailing in the line  5 . With the new deceleration factor which is formed from the sum of the deceleration factors a v1  and a h2 , the braking forces which correspond to this change to deceleration factor and which are to be applied to the front wheel or rear wheel are determined by reference to the diagram according to  FIG. 4 . In order to obtain these braking forces, the activation pressures prevailing in the lines  14  and  24  must be correspondingly increased. It may also be the case that the pressure prevailing in the line  14  has to be reduced, which depends on whether the value is to the left or right of the maximum value shown in  FIG. 4 . Since the activation pressure prevailing in the line  5  remains constant, the handbrake lever  1  is not affected by the additional activation of the footbrake lever  2 . For this reason, no feedback effects at all occur at the handbrake lever  1 . 
   If the footbrake is activated first and then the handbrake, a pressure p v2  is increased in the line  5  by the handbrake cylinder  4  and an additional braking force is applied to the front wheel, and the deceleration of the vehicle is correspondingly increased. The activation pressure prevailing in the line  5  is measured by the pressure sensor  6  and the deceleration factor a v2  associated with this pressure p v2  is determined by means of  FIG. 2 . This deceleration value a v2  is added to the deceleration factor a h1  defined by the activation of the footbrake, and the associated values for the braking forces to be applied to the front and rear wheels are determined by means of  FIG. 4  on the basis of the new deceleration factor formed in this way. Since the pressure prevailing in the line  5  is predefined by the rider, the necessary increase in the braking force acting on the front wheel must be brought about by a corresponding increase in the operating pressure prevailing in the line  24 . The corresponding pressure modulators are controlled by the electronic control unit in order to adjust the operating pressures prevailing in the lines  24  and  14  to the values necessary for optimum distribution of braking force. Since the pressure prevailing in the line  5  is not affected by these control processes, the handbrake lever  1  also remains unaffected so that the rider has a normal braking sensation. 
   Instead of the embodiment shown in  FIG. 1 , in which the front brake calipers have three pressure chambers, it is also possible to use conventional brake calipers with just one pressure chamber. As illustrated in  FIG. 5 , one of the two front brake calipers is connected to the line  5 , while the other front brake caliper is connected to the line  24 . For the rest, the design and the method of operation of the integral brake shown in  FIG. 5  are identical to those of the embodiment according to  FIG. 1 . 
   Alternatively, instead of the ideal (optimum) distribution of braking force between the front and rear wheels, it is also possible to implement any other distribution. 
   Ideally, the integral brake is operated with five pressure sensors as illustrated and described. However, it is basically also possible to operate with four pressure sensors  6 ,  15 ,  16  and  25  and to calculate the missing fifth pressure in the system by means of a pressure model. 
   LIST OF REFERENCE NUMERALS 
   
       
         1  Handbrake lever 
         2  Footbrake lever 
         3  Brake disk 
         4  Handbrake cylinder 
         5  Line 
         6  Pressure sensor 
         7  Inlet valve 
         8  Bypass line 
         9  Outlet valve 
         10  Pump 
         11  Electric motor 
         12  Rotational speed sensor 
         13  Footbrake cylinder 
         14  Line 
         15  Pressure sensor 
         16  Pressure sensor 
         17  Inlet valve 
         18  Bypass line 
         19  Outlet valve 
         20  Pump 
         21  Intake line 
         22  Suction valve 
         23  Parting valve 
         24  Line 
         25  Pressure sensor 
         26  Inlet valve 
         27  Bypass line 
         28  Outlet valve 
         29  Rotational speed sensor 
         30  Pressure sensor