Patent Publication Number: US-2011060510-A1

Title: Systems and Methods for Increasing Brake Pressure

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to systems and methods for increasing brake pressure using one or more pyrotechnic devices. 
     2. Background Art 
     A vehicle may be provided with an emergency brake intervention system that automatically builds up brake pressure in the event that a potential collision situation is detected. Such a system may detect a rapid closing of the vehicle on an obstacle using a radar system or other vision or laser rangefinder device. In the event that a collision situation is detected, brake pressure may be built up automatically by a vacuum brake booster or a pump of an antilock braking system. 
     SUMMARY 
     According to an embodiment of the present disclosure, a vehicle brake system may be provided with a brake unit, a brake line associated with the brake unit, and an activatable pyrotechnic device associated with the brake line. Upon activation, the pyrotechnic device is configured to supply gas directly into the brake line to increase pressure in the brake line, such that increased pressure is applied to the brake unit. 
     A method of increasing braking pressure in a vehicle brake system that includes a brake unit and a brake line associated with the brake unit is also provided. The method includes detecting a potential collision event, and activating a pyrotechnic device in response to detection of the potential collision event, such that gas is supplied directly into the brake line to increase pressure applied to the brake unit. 
     While exemplary embodiments in accordance with the invention are illustrated and disclosed, such disclosure should not be construed to limit the claims. It is anticipated that various modifications and alternative designs may be made without departing from the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a vehicle including a brake system in accordance with the present disclosure; 
         FIG. 2  is an enlarged view of a pyrotechnic device of the brake system of  FIG. 1 ; 
         FIG. 3  is a schematic view of a vehicle including another embodiment of a brake system in accordance with the present disclosure; and 
         FIG. 4  is a schematic view of a vehicle including yet another embodiment of a brake system in accordance with the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a motor vehicle  10  having a brake system  12  according to the present disclosure. The brake system  12  is configured to improve brake response of the vehicle  10 , as explained below in detail. 
     The brake system  12  may include one or more brake units  14  that are each associated with a particular wheel  16 , or other motion device, of the vehicle  100 . In the embodiment shown in  FIG. 1 , the brake system has four brake units  14 , including two front brake units  14   a,b  associated with front wheels  16   a,b,  and two rear brake units  14   c,d  associated with rear wheels  16   c,d.  Furthermore, each brake unit  14  may be any suitable brake device such as a disk brake device or a drum brake device. For example, each front brake unit  14   a,b  may include a disk brake device, and each rear brake unit  14   c,d  may include a drum brake device. 
     The brake units  14  are connected to one or more brake pumps, such as a master cylinder  18 , by one or more brake lines  20 , such as tubes and/or hoses, that contain a suitable brake fluid, such as hydraulic oil. The master cylinder  18  is configured to increase pressure in the brake lines  20  in response to a vehicle operator depressing a brake pedal  22 , which is operatively connected to or otherwise associated with the master cylinder  18 . For example, the brake pedal  22  may be connected directly or indirectly to a plunger or piston  24  of the master cylinder  18 , such that downward and/or forward movement of the brake pedal  22  may cause movement of the piston  24  from an initial position to a brake-actuate position. As a result, the master cylinder  18  forces brake fluid through the brake lines  20 , thereby applying increased pressure at the brake units  14 , which causes the brake units  14  to apply braking force on the wheels  16 . 
     In the embodiment shown in  FIG. 1 , the master cylinder  18  is connected to two brake lines  20   f,r.  The brake line  20   f  is connected to additional brake lines  20  that supply brake fluid to the front brake units  14   a,b,  and the brake line  20   r  is connected to additional brake lines  20  that supply brake fluid to the rear brake units  14   c,d.    
     The master cylinder  18  may also be in fluid communication with a reservoir  25  that contains additional brake fluid. The master cylinder  18  may draw brake fluid from the reservoir  25  as needed to sufficiently increase pressure in the brake lines  20 . 
     The brake system  12  further includes one or more pyrotechnic devices, such as pyrotechnic charges or cartridges, associated with one or more of the brake lines  20  for rapidly increasing pressure in the one or more brake lines  20 . Each pyrotechnic device may be any suitable device, such as a gas generator used in air bag system or seat belt pretensioner for example. In the embodiment shown in  FIG. 1 , the brake system  12  includes a single pyrotechnic device  26  that is connected to the brake line  20   f  downstream of the master cylinder  18 . For example, referring to  FIG. 2 , the pyrotechnic device  26  may be threadingly connected to a mount  28  that is also threadingly connected to portions of the brake line  20   f.    
     The pyrotechnic device  26  is configured to increase pressure in the brake line  20   f  as explained below in detail. Furthermore, the pyrotechnic device  26  may increase pressure in the brake line  20   f  to any suitable level, such as a pressure in the range of about 100 to 120 bar. 
     In another embodiment, an additional pyrotechnic device  26  may be connected to the brake line  20   r.  In yet another embodiment, a brake system according to the present disclosure may include a single pyrotechnic device  26  connected to the brake line  20   r,  and no pyrotechnic device connected to the brake line  20   f.    
     The brake system  12  shown in  FIG. 1  further includes an electronic brake controller  30  for controlling operation of the pyrotechnic device  26 , a collision detection system (CDS)  32  in communication with the controller  30 , and an anti-lock braking system (ABS) modulator  34  that is also in communication with the controller  30 . The controller  30  may include one or more control units or modules that each include, for example, a central processing unit (CPU) including a microprocessor, and a memory management unit (MMU) in communication with the CPU. The MMU may control movement of data among various computer readable storage media and communicate data to and from the CPU. In one embodiment, the computer readable storage media include stored data or code representing instructions executable by controller  30  to control operation of the pyrotechnic device  26  and/or ABS modulator  34  based on input from the CDS  32 . 
     The CDS  32  may be positioned at or near a front portion of the vehicle  10 , and may have any suitable components for sensing or otherwise detecting a potential collision event. For example, the CDS  32  may include a radar system and/or a laser system for detecting an obstacle or target in the path of the vehicle  10  or approaching the vehicle  10 . Alternatively or supplementally, the CDS  32  may include one or more sensors that sense a vehicle parameter that may be indicative of a potential collision event. For example, the CDS  32  may include an accelerometer  36  that is configured to detect sudden changes in vehicle acceleration. 
     The ABS modulator  34  is configured to control or regulate pressure in the brake lines  20  to inhibit or prevent lock up of any of the wheels  16  during braking events. In the embodiment shown in  FIG. 1 , the ABS modulator  34  is positioned downstream of the pyrotechnic device  26 . With this configuration, the ABS modulator  34  may be used to control or regulate pressure in the brake line  20   f,  which is connected to the pyrotechnic device  26 , to inhibit or prevent lock up of the front wheels  16   a,b  when the pyrotechnic device  26  is activated. In another embodiment, the ABS modulator  34  may be positioned upstream of the pyrotechnic device  26  or omitted from the brake system  12 . 
     Referring to  FIGS. 1 and 2 , operation of the brake system  12  will now be described. When the CDS  32  detects a potential collision event, such as by sensing the presence of an object and/or sensing a rapid change in acceleration of the vehicle  10 , that information is communicated to the controller  30 . The controller  30  may then activate the pyrotechnic device  26 , such as with an electrical signal, optical signal or mechanical impetus. When activated, such as by detonation or deflagration, the pyrotechnic device  26  introduces hot gas, such as nitrogen or any other suitable gas or gasses, directly into the brake line  20   f.  As a result, increased pressure is rapidly applied to the brake units  14   a,b  associated with the front wheels  16   a,b,  thereby causing the brake units  14   a,b  to automatically apply brake pressure to the front wheels  16   a,b  or to automatically increase brake pressure on the front wheels  16   a,b,  such that brake action of the vehicle operator may be reinforced. The brake line  20   f  may also include a flow regulator, such as a constricted region or a poppet valve, to inhibit or prevent flow of brake fluid toward the reservoir  25  when the pyrotechnic device  26  is activated. 
     With the above configuration, the pyrotechnic device  26  supplies gas directly into the brake line  20   f  such that the gas contacts the brake fluid. The gas may subsequently be bled out from the brake line or lines  20  through one or more bleed ports  38 , such that the brake system  12  may be returned to normal operation. 
       FIG. 3  shows another embodiment  12 ′ of a brake system according to the present disclosure. The brake system  12 ′ includes similar components as the brake system  12 , and those similar components are identified with the same reference numbers. Rather than including a single pyrotechnic device  26 , however, the brake system  12 ′ includes two pyrotechnic devices  26 . One pyrotechnic device  26   x   1  is connected to a first brake line  20   x   1 , and the other pyrotechnic device  26  is connected to a second brake line  20   x   2 . As shown in  FIG. 3 , the first brake line  20   x   1  is connected by additional brake lines  20  to the left front brake unit  14   b  and right rear brake unit  14   c,  and the second brake line  20   x   2  is connected by additional brake lines  20  to the right front brake unit  14   a  and left rear brake unit  14   d.    
     With such a configuration, in response to detection of a potential collision event by the CDS  32 , the controller  30  may be used to control operation of the pyrotechnic devices  26  to automatically apply braking force on all wheels  16  or reinforce braking action of the vehicle operator. As another example, the controller  30  may activate only one of the pyrotechnic devices  26  in response to detection of a potential collision event. 
       FIG. 4  shows yet another embodiment  12 ″ of a brake system in accordance with the present disclosure. The brake system  12 ″ includes similar components as the brake system  12 , and those similar components are identified with the same reference numbers. Rather than including a single pyrotechnic device  26 , however, the brake system  12 ″ includes four pyrotechnic devices  26 . Each pyrotechnic device  26  is associated with a particular brake unit  14 . For example, each pyrotechnic device  26  may be connected to a brake line  20  that is connected directly to a particular brake unit  14 . 
     With such a configuration, in response to detection of a potential collision event by the CDS  32 , the controller  30  may activate all of the pyrotechnic devices  26  to automatically apply braking force on all wheels  16 , or reinforce braking action of the vehicle operator. As another example, the controller  30  may selectively activate one or more of the pyrotechnic devices  26  in response to detection of a potential collision event. For instance, one or both pyrotechnic devices  26  on one side of the vehicle  10 ″ may be activated to introduce a yaw moment on the vehicle  10 ″ to cause the vehicle  10 ″ to turn toward or away from an obstacle. As a result, the direction of the vehicle  10 ″ may be adjusted or altered to optimize protection afforded by other safety features, such as safety devices or crumple zones, of the vehicle  10 ″. For example, if the vehicle  10 ″ is provided with a front crumple zone to dissipate energy, the pyrotechnic devices  26  may be selectively activated to cause the vehicle  10 ″ to turn toward an obstacle such that the front crumple zone contacts the obstacle. More generally, the pyrotechnic devices  26  may be selectively activated to cause the vehicle  10 ″ to turn such that collision energy transferred to a vehicle occupant may be minimized. 
     It should be noted that the brake lines  20  in the embodiment shown in  FIG. 4  may be arranged in any suitable configuration. For example, the brake lines  20  may be arranged in a front-rear split configuration in which one brake line from the master cylinder  18  supplies or feeds brake fluid to both front brake units  14   a,b,  and another brake line from the master cylinder  18  feeds brake fluid to both rear brake units  14   c,d.  As another example, the brake lines  20  may be arranged in an x-split configuration in which one brake line from the master cylinder  18  feeds brake fluid to the left front brake unit  14   b  and right rear brake unit  14   c,  and another brake line from the master cylinder  18  feeds brake fluid to the right front brake unit  14   a  and left rear brake unit  14   d.    
     While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.