Apparatus and method for enhancing performance of an occupant restraint system in a vehicle

Abstract: An apparatus enhances performance of an occupant restraint system (12) of a vehicle. A signal is generated based on vehicle dynamics and selectively places at least one safety module (14,16,19) in a heightened state of awareness in response to the signal. The vehicle dynamics can include at least one parameter based on wheel movement. The parameter based on wheel movement can be provided by an anti-lock brake control system and/or a traction control system, or the like. The safety module capable of being placed in a heightened state of awareness can include a three-point seatbelt, an airbag (14), a pyrotechnic buckle pretensioner (16) and/or an electro-mechanical retractor pretensioner (18) or the like.

Description: FIELD OF THE INVENTION The present invention relates to an apparatus and method for enhancing the ability of a restraint system in a vehicle to protect the occupants, and more particularly allows the restraint system to react to vehicle data other than G-force or inertia based triggers. BACKGROUND OF THE INVENTION Prior known restraint systems operate in response to sensors once the G-force or inertia thresholds (approximately 0.7 g's for seatbelts) required to activate the restraint system have been exceeded. Typically, seatbelt sensors are mechanical devices that activate the retractor, or more specifically, place the retractor in a "locked" position (no further webbing is allowed to pay out of the retractor once it has been locked). During normal airbag and pyrotechnic pretensioner (buckle or retractor) operation, these devices are operated according to a control program stored in memory that constantly monitors the operation and readiness of the restraint system, typically including a diagnostic routine that continually checks for any error signals from the sensors or other components of the restraint system indicating a component failure requiring repair, or other maintenance or service. While on-board diagnostics are desirable, continuous operation of the diagnostic routine during the normal operation of the vehicle restraint system controller requires the dedication of at least a portion of the processing time of the central processing unit to be allocated to the diagnostic routine rather than continuously monitoring the status of the sensors in preparation for activation of the restraint system to protect the occupants of the vehicle. From U.S. patent 5,201,385 it is known that a motor vehicle is equipped with an occupant seat belt system including a belt retractor having associated control mechanism such as a reel locking mechanism, a tension relieving mechanism, and/or a belt tensioning mechanism. The onset of an incipient wheel lock up condition sensed by the anti-lock brake system triggers the retractor associated mechanism so that restraint of the occupant is initiated in response to wheel condition independent of actuation by a sensed condition of vehicle deceleration. Major disadvantages may occur in triggering a seat belt or any other safety module or safety device comprised in a restraint system by a signal which indicates incipient wheel lock of a vehicle. Such signals are output by control devices whose objective is to modulate the brake force on vehicle wheels as an accident avoidance. Triggering a safety roll bar, an air bag, a belt retractor, or any other safety device of a restraint system in response to the detected lockup condition of a wheel can cause major irritations of the driver in critical situations, with the result of jeopardizing occupants' safety. In view of the above, it is the object of the present invention to provide an apparatus and a method for enhancing performance of an occupant restraint system for a vehicle to protect the occupants of the vehicle, wherein detection of an incipient wheel lock up condition is utilized to increase occupant safety while avoiding false activations of safety modules. This object is achieved by the features of the claims 1 and 4. An apparatus according to the present invention enhances performance of an occupant restraint system for a vehicle by (a) providing means for generating a signal based on vehicle dynamics including at least one parameter of wheel movement, and by (b) providing safety means for periodically performing a diagnostic subroutine function with respect to at least one crash sensor and for selectively placing at least one safety module in a heightened state of awareness, such as optimized position or optimized subroutine, in response to said signal, wherein said heightened state of awareness includes temporarily suspending periodic performance of said diagnostic subroutine function, wherein said signal generating means includes (c) control means for controlling wheel movement independent of one another and for providing said at least one parameter of wheel movement. A method according to the present invention enhances performance of an occupant restraint system for a vehicle by (a) generating a signal with a control means based on vehicle dynamics including at least one parameter of wheel movement, (b) periodically performing a diagnostic subroutine function with respect to at least one crash sensor with a safety means, and (c) in response to said signal, selectively placing at least one safety module in a heightened state of awareness with said safety means, wherein said heightened state of awareness includes temporarily suspending periodic performance of said diagnostic subroutine function, wherein said signal generating step includes (d) controlling wheel movement independent of one another and providing said at least one parameter of wheel movement with said control means. The present invention provides an early warning to the restraint system of a potential crash, allowing the restraint system to prepare itself for optimal performance. The present invention allows the restraint system to react to other vehicle data in addition to the G-force or inertia based sensors. The other vehicle data is potentially available prior to reaching the G-force or inertia threshold required to activate the restraint system. The present invention is suitable for use with signals generated by anti-lock brake control systems, anti-lock brake and traction assist systems (sometimes referred to as traction control systems or traction slip control systems), automotive stability management systems, interactive vehicle dynamics systems, intelligent cruise control systems or accident avoidance systems (hereinafter all these systems are referred to generically as accident avoidance systems). These systems can communicate dynamic vehicle parameters, such as wheel movement parameters, including wheel slip, yaw rate or the like, to a restraint system controller which can control at least one safety module as described in greater detail below. The apparatus may include one or more of the following safety modules: a three-point seatbelt, one or more airbags, (driver and passenger; front and/or side) pyrotechnic pretensioner (buckle or retractor) and/or an electro-mechanical retractor pretensioner. Where the safety module is a three-point seatbelt, the restraint controller can command the retractor to remove excess or slack webbing from the system and put the retractor in a locked position. An electro-mechanical retractor pretensioner (electric motor attached to the retractor shaft with additional means to put the retractor in a locked position) can spool the excess webbing into the retractor. Currently, retractors will not lock up until approximately 0.7 g's of force lockup threshold is reached. The webbing pays out until lockup, adding to the slack webbing that previously existed in the system. If the safety module is a pyrotechnic buckle or retractor pretensioner, or an airbag, or any combination thereof, the restraint controller according to the present invention can force the device to a heightened state of alert in the control software, once the restraint controller receives data from an anti-lock brake system, anti-lock brake system/traction control system, or interactive vehicle dynamic controller corresponding to certain predetermined criteria. In addition to generating a signal based on vehicle dynamics, such as at least one parameter of wheel movement (for example, wheel slip and yaw rate), the present invention could operate on other input data, such as brake lamp switch data or the like. Other objects, advantages and applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: Figure 1 is a schematic view of an apparatus for enhancing performance of an occupant restraint system for a vehicle according to the present invention; Figure 2 is a side view of an electro-mechanical retractor pretensioner means according to the present invention; Figure 3 is a perspective view of a pyrotechnic retractor pretensioner means shown in Figure 2 according to the present invention with certain portions broken away for clarity; Figure 4 is a simplified flow diagram of a control program according to the present invention for enhancing performance of an occupant restraint system of a vehicle; and Figure 5 is a simplified flow diagram of a portion of the control program stored in memory according to the present invention for activating a safety modular or device, such as a web retractor. DESCRIPTION OF THE PREFERRED EMBODIMENT An apparatus 10 according to the present invention enhances performance of an occupant restraint system 12 of a vehicle. The occupant restraint system 12 can include one or more of the following safety modules: an airbag 14, such as that stored in the central portion of a steering wheel, or in the dash in front of the passenger seat (commonly referred to collectively as the front airbags) and/or a side airbag; a pyrotechnic buckle or retractor 16; and an electro-mechanical retractor 18 capable of stowing excess webbing and engaging a pawl to a ratchet. The electro-mechanical retractor 18 can also have a pyrotechnic retractor pretensioner in addition to electro-mechanical portion, since some crashes could occur without unusual vehicle dynamics, such as slip or yaw, for example a head on collision without the brakes being applied. The apparatus 10 includes means 20 for generating a signal based on vehicle dynamics and safety means 22 for selectively placing at least one safety module of the occupant restraint system 12 in a heightened state of awareness in response to the signal. The signal generating means 20 can include an anti-lock brake system (ABS), an anti-lock brake system and traction control system (ABS/TCS), or an automotive stability management system (ASMS), or other interactive vehicle dynamics system (IVD). Anti-lock brake systems and/or traction control systems are generally known to those skilled in the art. For example, further details regarding anti-lock brake control systems and/or traction control systems can be obtained from US 4,869,559 A, US 4,861,117 A, US 4,919,495 A, US 5,007,687 A US 4,900,105 A. Generally, anti-lock brake control systems and/or traction control systems include control means 24 for controlling wheel movement independently of one another. The control means 24 includes wheel sensors 26 and electronic circuits for determining the wheel rotating pattern of the front right wheel 28, front left wheel 30, rear right wheel 32 and rear left wheel 34 and for generating electrical brake pressure control signals capable of controlling pressure fluid inlet and outlet valves 36 disposed in a conduit system 38 for wheel movement control. The brake system is actuated by the vehicle operator pressing down on the brake pedal 40, which typically is connected to a standard vacuum booster 42 and a tandem master cylinder 44 as is conventional. The tandem master cylinder 44 operably controls the hydraulic control unit 46 as is also conventional. Traditionally, safety modules forming part of an occupant restraint system 12, such as airbags 14, pyrotechnic buckle retractors or the like have been activated in response to crash sensors 48, such as accelerometers, G-force sensors, inertia sensors or the like. Typically, the occupant restraint system 12 included monitoring and diagnostic functions to test crash sensors 48 on a regular interval while the vehicle was being operated to determine if any sensor required maintenance or service, in addition to monitoring and actuating the trigger mechanism to actuate the safety module of the occupant restraint system 12. This dual function requires time on the part of the occupant restraint system 12 to perform the diagnostic subroutine, typically on a prescheduled periodic basis, and increases the cycle time between checks of the crash sensors 48 to determine if the occupant restraint system 12 should deploy or activate one or more of the safety modules. The apparatus 10 according to the present invention provides a signal generating means 20 for generating a signal based on vehicle dynamics and safety means 22 for selectively placing at least one safety module in a heightened state of awareness in response to the signal. The vehicle dynamics can include at least one parameter based on wheel movement. The one parameter based on wheel movement can be provided by either an anti-lock brake control system (ABS), or a traction control system (ABS/TCS), or an automotive stability management system (ASMS), or intelligent cruise control system, or accident avoidance system, or interactive vehicle dynamics (IVD) system. In any case, control means 24 is provided for controlling wheel movement and can provide at least one parameter based on wheel movement corresponding to vehicle dynamics for generating a signal based thereon. The control means 24 (either ABS, ABS/TCS, ASMS or IVD) informs the safety means 22 that one or more wheels are in a slip condition, and/or can inform the safety means 22 with respect to a vehicle stability parameter, such as wheel slip, yaw rate, or the like. The present invention also encompasses a method for enhancing performance of an occupant restraint system 12 of a vehicle as illustrated in the simplified flow charts of Figures 4 and 5. The safety means 22 can include a control program stored in memory for operating the method including the steps of generating a signal with the control means 24 based on vehicle dynamics, and in response to the signal, selectively placing at least one safety module in a heightened state of awareness with safety means 22. The control program stored in memory can include the steps as indicated in Figure 4 including initializing the routine and starting the control program as indicated in step 100. In step 102, a determination of vehicle stability parameters is conducted. The monitored vehicle stability parameter is then compared with a predetermined vehicle stability threshold in step 104. Based on the comparison, if the monitored vehicle stability parameter is less than the predetermined threshold, the program returns to step 102 to again determine the vehicle stability parameter. Based on the comparison, if the monitored vehicle stability parameter is greater than or equal to the predetermined vehicle stability threshold, the program continues on to step 106 to alert one or more safety modules. When in the alert mode, the program monitors the vehicle instability status in step 108 and compares the monitored vehicle stability parameter to the predetermined threshold to determine if the vehicle is still unstable in step 110. Based on the comparison of step 110, if the vehicle is still unstable, the program returns to step 108 to further monitor the vehicle instability status. If the comparison of step 110 determines that the vehicle is no longer unstable, the control program continues to step 112 where the program is returned to a normal operating state and returns to step 102 to again determine the vehicle stability. The alert safety module step 106 can be accomplished via a message on a bus or through a hard wired signal. When the safety module is alerted in step 106, the safety module enters a heightened state of alert. In this heightened state of alert, the safety module uses the most efficient subroutines for actuation of the safety module, such as an airbag, pyrotechnic buckle, pyrotechnic retractor, or electro-mechanical retractor. This may mean temporarily disabling safety module diagnostics, operational parameter identification (PID), or the like during the event, thereby decreasing controller loop time and improving the ability of the controller to react in a shorter time period. Step 108 monitor the vehicle instability status and can be performed via a message on a bus or a hard wired signal from the anti-lock brake system, anti-lock brake system and traction control system, or automotive stability management system (ASMS) module. For purposes of illustrating the present invention, a simplified flow diagram for the actuation of a safety module corresponding to an electro-mechanical web retractor is illustrated in Figure 5. When the safety module is alerted pursuant to the alerting step 106 of Figure 4, the safety module activates the web retractor in step 114. As seen in Figures 2 and 3, the electro-mechanical web retractor includes a motor 120 for stowing webbing 122 on spool 124. The motor 120 turns a shaft connected to the retractor spool 124 in order to stow the excess or slack portion of webbing 122 on the spool prior to any collision. The program compares the motor resistance in step 116 with a predetermined motor resistance value. If the motor resistance has not reached the predetermined resistance value, the program returns to step 114 to continue activation of the web retractor. If the motor resistance has exceeded the predetermined motor resistance value, the program continues to step 118 to complete the web retractor readiness. Completing the web retractor readiness could include steps, such as turning off the motor 120 to stop stowing webbing 122 on the spool 124 of the retractor, placing the pawl 126 in an engaged position with respect to a ratchet 128 connected to the spool 124 to prevent deployment of webbing 122 from spool 124. Typically, an occupant restraint system safety module, such as seatbelts formed of webbing 122, are set for a G-force threshold of approximately 0.7 G's. The apparatus and method according to the present invention can enable pretensioning of the seatbelt webbing 122 and positive locking of the ratchet and pawl mechanism, such as by actuator 130 for driving the pawl 126 into locking engagement with the ratchet 128 prior to a collision. The actuator 130 can include any electrically actuated motor, such as a solenoid for driving the pawl 126 into the ratchet 128, in addition to the normal inertia or acceleration actuation operation of the pawl 126 and ratchet 128 assembly. When returning to a normal operational state pursuant to step 112, the pawl 126 would be disengaged from the ratchet 128 in order to allow webbing 122 to be removed from spool 124.

Claims: An apparatus (10) for enhancing performance of an occupant restraint system (12) for a vehicle, having: (a) means (20) for generating a signal based on vehicle dynamics including at least one parameter of wheel movement, and (b) safety means (22) for periodically performing a diagnostic subroutine function with respect to at least one crash sensor (48) and for selectively placing at least one safety module (14, 16, 18,122) in a heightened state of awareness in response to said signal, wherein said heightened state of awareness includes temporarily suspending periodic performance of said diagnostic subroutine function, wherein said signal generating means (20) includes: (c) control means (24) for controlling wheel movement independent of one another and for providing said at least one parameter of wheel movement. The apparatus of claim 1, wherein said at least one parameter of wheel movement is provided by an anti-lock brake control system or a traction control system. The apparatus of claim 1 or 2, wherein said at least one safety module (14,16,18,122) is selected from a group consisting of a three-point seat belt (122), an air bag (14), a pyrotechnic buckle pretensioner (16) and a retractor pretensioner (18). A method for enhancing performance of an occupant restraint system (12) for a vehicle, characterized in the steps of: (a) generating (102, 104, 106) a signal with a control means (24) based on vehicle dynamics including at least one parameter of wheel movement, (b) periodically performing a diagnostic subroutine function with respect to at least one crash sensor (48) with a safety means (22), and (c) in response to said signal, selectively placing at least one safety module (14, 16, 18,122) in a heightened state of awareness with said safety means (22), wherein said heightened state of awareness includes temporarily suspending periodic performance of said diagnostic subroutine function, wherein said signal generating step includes: (d) controlling wheel movement independent of one another and providing said at least one parameter of wheel movement with said control means (24). The method of claim 4, wherein said signal generating step includes: (a) determining (102) a vehicle stability parameter based on said vehicle dynamics; (b) comparing (104) said vehicle stability parameter with a predetermined vehicle stability threshold; (c) if said vehicle stabilityparameter is within said predetermined vehicle stability threshold, return to the determining step (102); (d) if said vehicle stability parameter is beyond said predetermined vehicle stability threshold, alert (106) said at least one safety module by generating said signal. The method of claim 5, wherein said signal generating step includes: (a) if said vehicle stability parameter is beyond said predetermined vehicle stability threshold, monitoring (108) vehicle instability status, (b) comparing (110) said vehicle instability status to said predetermined vehicle stability threshold, (c) if said vehicle instability status is beyond said predetermined vehicle stability threshold, returning to the monitoring step (108), (d) if said vehicle instability status is within said predetermined vehicle stability threshold, initializing to a normal operational state (112), wherein said heightened state of awareness is terminated, and returning to the determining step (102). The method of claim 6, wherein said at least one safety module corresponds to a web retractor including a motor (120), further characterized in the steps of: (a) in response to said signal, activating (114) said web retractor, (b) monitoring motor resistance, (c) comparing (116) said monitored motor resistance to a predetermined motor resistance value, (d) based on said comparing step (116), if said predetermined motor resistance value is greater than said monitored motor resistance, continuing to activate (114) said web retractor, and (e) based on said comparing step (116), if said monitored motor resistance is at least as great as said predetermined motor resistance value, completing (118) web retractor readiness and discontinuing activation of said web retractor. The method of one of the claims 4-7, wherein said at least one parameter of wheel movement is provided by an anti-lock brake control system or a traction control system.

Inventors: DIXON SCOTT M, DIXON, SCOTT M.
Applicants: CONTINENTAL TEVES INC, CONTINENTAL TEVES, INC.
Application year: 1996
Main classification: B60R22
IPC codes: B60T8, B60R22, B60R21