Abstract:
The invention specifies a sensor arrangement for a brake system for braking a wheel in a vehicle, which brake system includes a travel sensor for detecting a position of a brake pedal of the brake system, wherein the travel sensor is provided for detecting operation of the brake pedal based on the position of the brake pedal and for outputting a signal which indicates operation of the brake pedal.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. National Phase Application of PCT/EP2012/058466, filed May 8, 2012, which claims priority to German Patent Application Nos. 2011 075 534.9, filed May 9, 2011 and 10 2011 088 753.9, filed Dec. 15, 2011, the contents of such applications being incorporated by reference herein. 
     FIELD OF THE INVENTION 
     The invention relates to a sensor arrangement for a brake system for braking a wheel in a vehicle, to the vehicle and to a method for controlling a display means for displaying operation of a brake pedal in a vehicle. 
     BACKGROUND OF THE INVENTION 
     For safety reasons, vehicles must be provided with a brake light which indicates the operation of the brake to a vehicle traveling behind by means of a light signal. 
     SUMMARY OF THE INVENTION 
     An aspect of the invention improves the detection of the operation of the brake. 
     An aspect of the invention proposes deriving the operation of the brake from the position of a brake pedal controlling the brake. 
     An aspect of the invention is based on the consideration that operation of the brake system by the driver could usually be detected using contactless switches. These switches could be fitted, for example, to the pedal or to the tandem master cylinder, in which case, after brake operation by the driver has been detected via a circuit containing the switch, a corresponding item of brake operation information or a corresponding brake operation signal can be generated and provided. 
     Another aspect of the invention is based on the consideration that the switch is redundant in brake systems which already have a travel sensor for detecting the position of the brake pedal since an unambiguous item of information with regard to whether or not the brake pedal is moved and the brake of the brake system is therefore operated can also be derived from the position of the brake pedal. 
     Therefore, an aspect of the invention specifies a sensor arrangement for a brake system for braking a wheel in a vehicle, said arrangement comprising a travel sensor for detecting a position of a brake pedal of the brake system, the travel sensor being provided for the purpose of detecting operation of the brake pedal on the basis of the position of the brake pedal and outputting a signal which indicates the operation of the brake pedal. 
     The use of the travel sensor for the purpose of detecting brake operation dispenses with a redundant switch, which results in noticeable cost savings. In addition, the installation space needed to accommodate the redundant switch including its circuit is dispensed with, as a result of which considerable space savings are also noticeable. Finally, the wiring complexity is also reduced, for example on the part of the vehicle manufacturer, since the switch which has been dispensed with and its circuit no longer need to be incorporated in the communication network of the vehicle. 
     The travel sensor is preferably provided for the purpose of detecting the operation of the brake pedal if the position of the brake pedal exceeds a predetermined threshold value. In this manner, not only the operation of the brake pedal but also the end of operation of the brake pedal and thus the brake of the brake system can be detected using a single criterion. 
     Alternatively or additionally, the travel sensor may be provided for the purpose of detecting the operation of the brake pedal if a gradient of the position of the brake pedal has a value different from zero. In this manner, the operation of the brake pedal can be directly detected from the zero position of the brake pedal, with the result that there is no need to first wait until a particular threshold value. 
     In this case, the travel sensor may be provided, in a particularly favorable manner, for the purpose of activating or deactivating the signal on the basis of gradients. For example, the signal could be permanently activated by the detection of a positive gradient different from zero, while the signal is permanently deactivated by the detection of a negative gradient different from zero since the direction of movement of the pedal is clear from the gradient and it is thus possible to determine whether the driver is currently pressing the brake pedal or releasing the latter. 
     In another development of the invention, the position of the brake pedal is superimposed in the signal on the information with regard to whether the brake pedal is operated. In this manner, a plurality of items of information can be transmitted to the circuit units superordinate to the sensor arrangement in the communication network of the vehicle using a single data cable. The reduced wiring complexity thus makes it possible to save costs, space and production expenditure caused by wiring. 
     In one particular development of the invention, the travel sensor is provided for the purpose of outputting a further signal which indicates the position of the brake pedal. Separately outputting the signal indicating the position and the signal indicating brake operation makes it possible for the two signals to be transmitted independently of one another according to different criteria such as failure safety, information throughput, etc. 
     In one preferred development of the invention, the travel sensor is provided for the purpose of superimposing a supply voltage of the travel sensor on the signal. This makes it possible to use another line which is already present in the brake system of the vehicle to transmit the signal in order to reduce wiring complexity. 
     The invention also specifies a brake system for braking at least one wheel of a vehicle, said system comprising a brake pedal for generating a brake signal on the basis of a position of the brake pedal, a stated sensor arrangement and an electronic control unit for detecting the signal and for outputting a control signal for a display means if the signal indicates the operation of the brake pedal. 
     The invention also specifies a vehicle comprising at least one wheel and a stated brake system for braking the wheel. 
     The invention also specifies a method for controlling a display means for displaying operation of a brake pedal in a vehicle, said method comprising the steps of detection of a position of the brake pedal, detection of operation of the brake pedal on the basis of the position of the brake pedal, and control of the display means if the operation of the brake pedal has been detected. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-described properties, features and advantages of this invention and the manner in which they are achieved become more clearly and distinctly comprehensible in connection with the following description of the exemplary embodiments which are explained in more detail in connection with the drawings, in which: 
         FIG. 1  shows part of a communication network in a vehicle having a travel sensor according to a first exemplary embodiment of the invention, 
         FIG. 2  shows part of a communication network in a vehicle having a travel sensor according to a second exemplary embodiment of the invention, 
         FIG. 3  shows part of a communication network in a vehicle having a travel sensor according to a third exemplary embodiment of the invention, and 
         FIG. 4  shows part of a communication network in a vehicle having a travel sensor according to a fourth exemplary embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference is made to  FIG. 1  which shows part of a communication network  2  in a vehicle having a travel sensor  4  according to a first exemplary embodiment of the invention. 
     The travel sensor  4  comprises a sensor device  5  and an electronic control unit  6  (called ECU  6  below) which belongs to a brake system (not illustrated in any more detail). The ECU communicates with a central motor vehicle control unit  8 . 
     The sensor device  5  comprises a sensor element  10  which is connected to a brake pedal  12  of the vehicle and outputs the position of the brake pedal  12  to a microcontroller  14  in the sensor device  5  in the form of a measurement variable (not described in any more detail). In this case, the position of the brake pedal  12  may be a distance and/or angle size. The microcontroller  14  converts the position of the brake pedal  12  into an electronic measurement signal  16  and outputs it to the ECU  6  via an interface  18 . The sensor device  5  is also supplied with a supply voltage  20  with respect to a ground potential  22  from the ECU  6  via the interface  18 . 
     The ECU  6  has a voltage source  24  from which it outputs the supply voltage  20  via an interface  26  present in the ECU  6 . The ECU  6  also has its own microcontroller  28  which receives the measurement signal  16  containing the position of the brake pedal and electronically conditions said signal. Conditioning may comprise, for example, noise filtering and/or coding of the measurement signal  16 . 
     The conditioned measurement signal  30  is then sent, via a transceiver  32  and the interface  26 , to the motor vehicle control unit which can use the conditioned measurement signal  30  for control purposes within the scope of the anti-lock braking system, for example. In addition to the microcontroller  28 , the ECU  6  has a signal decoder  34  which likewise receives the electronic measurement signal  16 . The signal decoder  34  analyses the measurement signal  16  with respect to operation of the brake pedal  12 . For this purpose, the signal decoder  34  can compare the measurement signal  16  with a threshold value  36 , for example, and can output the operation of the brake pedal  12  as an operation signal  38  if the measurement signal  16  exceeds the threshold value  36 . The threshold value  36  may be externally supplied to the signal decoder  34 , as shown, or may be internally stored in the signal decoder  34 . Alternatively or additionally, the signal decoder  34  may determine, for example, a change in the measurement signal  16  on the basis of the gradient of the measurement signal  16 , for example, and may thus infer operation of the brake pedal  12 . In order to determine whether the driver closes or opens the brake, the signal decoder  34  may consider the mathematical sign of the gradient, for example. If the measurement signal  16  changes and the driver closes the brake, the signal decoder  34  switches on the operation signal  38 . If the measurement signal  16  changes and the driver opens the brake, the signal decoder  34  switches off the operation signal  38 . The operation signal  38  is output directly to a brake light system  42  via a hardware output  40  and the interface  26  in the ECU  6  in order to activate said system. 
     Reference is made to  FIG. 2  which shows part of a communication network  2  in a vehicle having a travel sensor  4  according to a second exemplary embodiment of the invention. 
     In  FIG. 2 , the same elements as in  FIG. 1  are provided with the same reference symbols and are not described again. 
     In the exemplary embodiment in  FIG. 2 , the signal decoder  34  is situated in the sensor device  5 . In this case, the operation signal  38  is transmitted, via its own line, to the interface  26  of the ECU  6  via the interface  18  of the sensor device  5  and is finally transmitted to the hardware output  40 . 
     Reference is made to  FIG. 3  which shows part of a communication network  2  in a vehicle having a travel sensor  4  according to a third exemplary embodiment of the invention. In  FIG. 3 , the same elements as in  FIGS. 1 and 2  are provided with the same reference symbols and are not described again. 
     In the exemplary embodiment in  FIG. 3 , the signal decoder  34  is situated in the sensor device  5  again. This time, the operation signal  38  is output directly to the brake light system  42  without passing through the ECU  6 . Therefore, faults in the ECU  6  do not influence the function of the brake light system  42 . 
     Reference is made to  FIG. 4  which shows part of a communication network  2  in a vehicle having a travel sensor  4  according to a fourth exemplary embodiment of the invention. In  FIG. 4 , the same elements as in  FIGS. 1 and 2  are provided with the same reference symbols and are not described again. 
     In the exemplary embodiment in  FIG. 4 , the signal decoder  34  is situated in the sensor device  5  again. This time, the operation signal  38  is modulated onto the supply voltage  20  and is thus transmitted between the sensor device  5  and the ECU  6  via the line of the supply voltage  20 . The modulation may be effected, for example, by simply superposing the supply voltage  20  and the operation signal  38 .