Abstract:
A brake assembly for a motorcycle provided with a hydraulically actuated front brake and rear brake for a front wheel and a rear wheel, respectively, including, first brake actuating means and second brake actuating means applying hydraulic pressure, and an electronic control means, having a first hydraulic system extending from the first brake actuating means connected to the front brake, and a second hydraulic system extending from the second brake actuating means connected to the rear brake, the electronic control means receiving detection values from each of a first actuation amount detection means for detecting an actuation amount of the first brake actuating means, and second actuation amount detection means for detecting an actuation amount of the second brake actuating means and subjecting the values to computation, outputting control signals to a first hydraulically controlled actuator and a second hydraulically controlled actuator based on the result of computation, and actuating the front brake using the first hydraulically controlled actuator and actuating the rear brake using the second hydraulically controlled actuator.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a brake assembly for a motorcycle provided with a hydraulically driven front wheel brake and rear wheel brake, for relational control of the two brakes. 
     2. Background Art 
     A motorcycle brake actuation is carried out using a brake lever provided on the handlebar and a brake pedal provided on a step. A braking force is distributed to the front wheel brake and rear wheel brake according to actuation of each of the actuating means. 
     Japanese Patent Laid-open Publication No. Hei. 7-196068, discloses a brake system using partial electronic control. The brake system of this example is shown in FIG.  7 . 
     A front wheel brake  02  and a rear wheel brake  05  are hydraulic brakes. A lever master cylinder  07  is provided on a brake lever of actuating means, while a pedal master cylinder  012  is provided on a brake pedal  011 . 
     A lever hydraulic system  08  extending from the lever master cylinder  07  is connected to the front wheel brake  02 . A pedal hydraulic system  013  extending from the pedal master cylinder  012  is connected to one port of the three port type rear wheel brake  05 . A hydraulic circuit  014  branching from the pedal hydraulic system  013  is connected to a secondary master cylinder  010 , and the output of the secondary master cylinder  010  is connected to the other 2 ports of the rear wheel brake  05  through a control valve  016 . 
     A brake switch  04  opened and closed by rotation of the other brake lever  06  is provided on the brake lever  06 . A pressure sensor  041  for detecting hydraulic pressure is provided in the lever hydraulic system  08 . A control unit  031  determines hydraulic pressure to be generated at the secondary master cylinder  010  based on each of the detection signals from the brake switch  040  and the pressure sensor  041 , and actuates an actuator  033  via a relay  032 , so that the secondary master cylinder  010  generates the hydraulic pressure as determined. These devices constitute an electronically controlled braking system. 
     When the brake pedal  011  is actuated independently, only the rear wheel brake  05  side is actuated disassociated from the front wheel. 
     When the brake lever  06  is actuated independently, or at the same time as the brake lever  011 , the front wheel brake  02  is actuated by hydraulic pressure of the lever master cylinder  07 , and the actuator  033  is actuated based on hydraulic pressure of the lever hydraulic system  08  to generate necessary hydraulic pressure in the secondary master cylinder  010  so that the rear wheel brake is actuated by the control valve  016 . 
     The pedal hydraulic system  013 . branches into 2 sections, with pipes leading to the rear wheel brake  05  and to the secondary master cylinder  010 , and the control valve  016  is located between the secondary master cylinder  010  and the rear wheel brake  05 . This means that the structure has many components and is complicated, and the operation of installing the piping and also maintenance can not be carried out easily. 
     The layout of the piping is also subject to restrictions, and there is little degree of freedom in the design. 
     SUMMARY OF THE INVENTION 
     The present invention has been conceived in view of the above described problems, and the object of the invention is to provide a brake assembly for a motorcycle that does not restrict an operator&#39;s brake controlling operation, with electronic control independently executed with a great degree of freedom, and which can reduce the number of components and the number of assembly steps. 
     In order to achieve the above described object, the present invention provides a brake assembly for a motorcycle provided with a hydraulically actuated front brake and rear brake for a front wheel and a rear wheel, respectively, including a first brake actuating means and second brake actuating means applying hydraulic pressure; and an electronic control means, having a first hydraulic system extending from the first brake actuating means connected to the front brake, and a second hydraulic system extending from the second brake actuating means connected to the rear brake, with the electronic control means receiving detection values from each of a first actuation amount detection means for detecting actuation amount of the first brake actuating means, and a second actuation amount detection means for detecting an actuation amount of the second brake actuating means and subjecting the values to computation, outputting control signals to a first hydraulically controlled actuator and a second hydraulically controlled actuator based on the result of computation, and actuating the front brake using the first hydraulically controlled actuator and actuating the rear brake using, the second hydraulically controlled actuator. 
     If the first brake actuating means is actuated, the front wheel brake is actuated via the first hydraulic system and the actuating amount is detected by the first actuating amount detection means and output to the electronic control means. If the second brake actuating means is actuated, the rear wheel brake is actuated via the second hydraulic system, and the actuating amount is detected by the second actuating amount detecting means and output to the electronic control means. 
     The electronic control means carries out computation based on the inputted detected values of the actuating amount, outputs respective control signals to a first hydraulic control actuator and a second hydraulic control actuator, and the front wheel brake and rear wheel brake are actuated with optimally distributed braking force in accordance with these control signals. 
     The front wheel brake and rear wheel brake can be controlled by respective independent electronically controlled braking systems of the first hydraulically controlled actuator, and the second hydraulically controlled actuator, so that interference between the hydraulic pressures applied to the front and rear wheel brakes does not occur. Additionally, these brakes can perform the control operation with a large degree of freedom, and it is possible to reflect effective braking without restricting the rider&#39;s brake controlling operation. 
     The piping of a hydraulic system without a control valve can be simplified and shortened, the number of components can be reduced, and the piping and maintenance operations can also be made easier. 
     The actuation of the front wheel brake is controlled by two systems, namely the first hydraulic system and the electronically controlled braking system, which means that even if there is a failure of one system the brake can be actuated by the other system. Similarly, actuation of the rear wheel brake is controlled by the second hydraulic system and the electronically controlled braking system, so again, it can be actuated by the remaining system if one system fails. 
     A second aspect of the present invention is a brake assembly of the first aspect in which the first brake actuating means is a lever master cylinder, and the second brake actuating means is a pedal master cylinder. 
     The first hydraulic system is connected between the lever master cylinder and the front wheel brake, while the second hydraulic system is connected between the pedal master cylinder and the rear wheel brake. This means that the piping can be made short, assembly is simple and there is a large degree of design freedom. 
     Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
     FIG. 1 is a schematic diagram showing a braking system for a motorcycle adopting the brake assembly of an embodiment of the present invention; 
     FIG. 2 is a structural diagram of the braking system shown in FIG. 1; 
     FIG. 3 is a diagram showing variations over time of rear brake hydraulic pressure and front brake hydraulic pressure when a brake pedal is independently actuated; 
     FIG. 4 is a drawing showing braking force distribution for the front brake and the rear brake when the brake pedal is independently actuated; 
     FIG. 5 is a diagram showing variations over time of rear brake hydraulic pressure and front brake hydraulic pressure when the brake pedal is actuated while the brake lever is actuated; 
     FIG. 6 is a diagram showing braking force distribution for the front brake and the rear brake when the brake pedal is actuated while the brake lever is actuated; and 
     FIG. 7 is a structural diagram of a braking system of a conventional brake assembly. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a schematic diagram showing a braking system for a motorcycle  1  adopting the brake assembly of an embodiment of the present invention. 
     An hydraulic pressure type front wheel brake  11  is provided on a front wheel  2 , and a hydraulic pressure type rear brake  12  is also provided on the wheel  3 . Both the front and rear brakes are disk brakes, comprising brake disks  11   a  and  12   a , and brake calipers  11   b  and  12   b.    
     A brake lever  5  is located on the right side handlebar, while a brake pedal  7  is located close to a right side step. The brake lever  5  is attached to a lever master cylinder  15 , and the brake pedal  7  is attached to a pedal master cylinder  17 . 
     Piping of a lever hydraulic system  16  extending from the lever master cylinder  15  is connected to the brake caliper  11   b  of the front wheel brake  11 , and piping of a pedal hydraulic system  18  extending from the pedal master cylinder  17  is connected to the brake caliper  12   b  of the rear wheel brake  12 . 
     An electronically controlled actuator  21  is arranged close to the front wheel brake  11 , and the electronically controlled actuator  21  and the front wheel brake  11  are connected by piping of an electronically controlled lubrication system  22 . 
     Similarly, an electronically controlled actuator  23  is arranged close to the rear wheel brake  12 , and the electronically controlled actuator  23  and the rear wheel brake  12  are connected by piping of an electronically controlled lubrication system  24 . 
     The front and rear electronically controlled actuators  21  and  23  are controlled by an electronic control unit (ECU)  30 . Respective hydraulic pressure detection signals of the lever hydraulic system  16  and the pedal hydraulic system  18  are input to the ECU  30 . 
     The structure of the brake system described above is shown in FIG.  2 . 
     An anti-skid braking system (ABS)  23  is installed in the lever hydraulic system  16 , and a pressure sensor  31  is also provided. The pressure sensor  31  detects actuation pressure generated in the lever master cylinder  15  by actuation of the brake lever  5  and outputs a detection signal to the ECU  30 . 
     Similarly, an ABS  34  is also installed in the pedal hydraulic system  18 , and a pressure sensor  32  is also provided. The pressure sensor  32  detects actuation pressure generated in the pedal master cylinder  17  by actuation of the brake pedal  7  and outputs a detection signal to the ECU  30 . 
     The front wheel brake  11  and the rear wheel brake  12  are both three port type brakes, in which the brake calipers  11   b  and  12   b  have three pistons. One of the three ports in each caliper is connected to the lever hydraulic system  16  or the pedal hydraulic system  18 , with the remaining two ports being connected to the electronically controlled hydraulic systems  22  and  24 . 
     If the brake lever  5  is independently actuated, hydraulic pressure is supplied to the front wheel brake  11  through the lever hydraulic system  16  and the front wheel  2  is braked, and at the same time the pressure sensor  31  detects the lever actuating pressure and outputs it to the ECU  30 . Suitable hydraulic pressure is then supplied to the front wheel brake  11  and the rear wheel brake  12  by controlling each of the electronically controlled actuators  21  and  23  based on this detection signal, and braking force is thus applied in an appropriately distributed manner and at an appropriate timing to the front wheel  2  and the rear wheel  3 . 
     Similarly, if the brake pedal  7  is independently actuated, hydraulic pressure is provided to the brake caliper  12   b  of the rear wheel brake  12  via the pedal hydraulic system  18 , the pressure sensor  32  detects the pedal actuating pressure and outputs it to the ECU  30 , and the ECU  30  then carries out a computation based on this detection signal, outputs control signals to each of the electronically controlled actuators  22  and  23 , and provides suitable hydraulic pressure to the front wheel brake  11  and the rear wheel brake  12  using the electronically controlled actuators  21  and  23 , so that braking force is thus applied in an appropriately distributed manner and at an appropriate timing to the front wheel  2  and the rear wheel  3 . 
     An example of the control executed by the ECU  30  at the time of independent actuation by the brake pedal  7  will be described based on the graphs of FIG.  3  and FIG.  4 . 
     FIG. 3 is a drawing showing correspondence between front brake hydraulic pressure variation over time and rear brake hydraulic pressure variation over time when the brake pedal  7  is independently actuated. When the brake pedal  7  is depressed, hydraulic pressure is supplied to the rear brake through the pedal hydraulic system  18  and the rear brake hydraulic pressure is raised. If the rear brake pressure exceeds a fixed value P, the electronically controlled actuator  21  is caused to actuate and braking force is applied to the front wheel  2  by supplying hydraulic pressure to the front brake  11 . 
     A distribution characteristic of the front brake force and the rear brake force under this control is shown in FIG.  4 . 
     Specifically, if the brake pedal  7  is actuated, first of all the brake comes into contact with the rear wheel, and with further depression of the pedal the rear brake hydraulic pressure in increased and if it exceed a fixed value the front wheel brake is actuated using the electronically controlled hydraulic system  22 . 
     Accordingly, it is possible to prevent the vehicle nose-diving at the time of braking. 
     In the above description, the brake pedal  7  is actuated independently without actuating the brake lever  5 , but in the case where there is input to brake lever  5  before actuation of the brake pedal  7 , the above described control will not be carried out. 
     An example of the control for this case is shown in FIG.  5  and FIG.  6 . 
     In FIG. 5, showing the correspondence between variations over time of rear brake hydraulic pressure and front brake hydraulic pressure. When the brake lever  5  is actuated, hydraulic pressure is supplied to the front brake  11  through the lever hydraulic system  16  and the front brake hydraulic pressure {circle around (1)} is applied to the front wheel  2 . At the same time, appropriately controlled hydraulic pressure is supplied to the rear brake  12  by the electronically controlled actuator  23 , and the rear brake hydraulic pressure {circle around (2)} is applied to the rear wheel  3 . 
     In the state where the brake lever  5  is actuated and braking force is applied in a suitably distributed manner to the front wheel  2  and the rear wheel  3 , as described above, if there is input to the brake pedal  7 , hydraulic pressure is supplied to the rear brake  12  through the pedal hydraulic system and the rear brake hydraulic pressure {circle around (2)} is further applied to the rear wheel  3 . 
     Here, in the case where the brake pedal  7  is actuated independently, if the rear brake hydraulic pressure {circle around (3)} is not equal to or greater than a fixed value P, hydraulic pressure is not supplied to the front brake  11  by the electronically controlled actuator  21 , but, referring to the broken lines in the drawing, if the brake pedal  7  is actuated after the brake lever  5  has been actuated, hydraulic pressure is supplied by the electronically controlled actuator  21  to the front brake  11  at the same time as input to the brake pedal  7 , and the front brake hydraulic pressure {circle around (4)} is further applied to the front wheel  2 . 
     A rear wheel braking force and front wheel braking force characteristic for this control is shown in FIG.  6 . 
     In FIG. 6, the diagonally hatched section is a lock region where the vehicle is stationary. 
     First of all, the brake lever  5  is actuated and braking force is applied in a suitably distributed manner to the front wheel  2  and the rear wheel  3  (shown in the section (a) in FIG.  6 ). If the brake pedal  7  is now actuated, further braking force is applied simultaneously to the front wheel  2  and the rear wheel  3  as shown by the characteristic in FIG. 6, section (b). Control is carried out to lock the rear wheel at a high point of the front brake force, making it possible to obtain effective braking force. 
     At the time of input to the brake pedal  7 , if control is carried out such as that for when the brake pedal  7  is actuated independently, as described above, only the rear brake force is further applied, as shown in FIG. 6, section (c), and the rear wheel rapidly enters the lock region, which is disadvantageous. In order to avoid this situation it is possible to apply braking force to the front wheel  2  and rear wheel  3  in an effectively distributed manner. 
     In this embodiment, ABS  33  and ABS  34  are respectively installed in the lever hydraulic system  16  and the pedal hydraulic system  18 , which means that even if the wheels enter the lock region the locked state can be released if necessary. 
     As has been described above, the electronically controlled hydraulic systems  22  and  24  have the lever hydraulic system  16  and the pedal hydraulic system  18  made independently only by the hydraulic pressure, which means that no interference occurs between the two hydraulic pressures and there is increased freedom with respect to electronic control. 
     Also, it is possible to achieve effective braking control without restricting the braking operation of the user. 
     The lever hydraulic system  16  is connected between the lever master cylinder  15  and the front brake  11 , while the pedal hydraulic system,  18  is connected between the pedal master cylinder  17  and the rear brake. This means that the piping can be made short. 
     The electronically controlled hydraulic system  22  is located close to the front brake  11 , and the electronically controlled hydraulic system  24  is positioned close to the rear brake which also means the piping can be designed short, thus simplifying the piping for the hydraulic systems, reducing the number of components and making assembly and maintenance operations easy. 
     Actuation of the front brake  11  is controlled by two systems, namely the lever hydraulic system  16  and the electronically controlled hydraulic system  22 , which means that even if one system fails, the front brake can be actuated by the other system. Similarly, actuation of the rear brake  12  is also controlled by two systems, namely the pedal hydraulic system  18  and the electronically controlled hydraulic system  24 , which means that even if one system fails, the rear brake can be actuated by the other system. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.