Patent Publication Number: US-2020298808-A1

Title: Multiple-stage collision avoidance braking system and method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a Continuation of co-pending U.S. application Ser. No. 16/188,175, filed Nov. 12, 2018, which is a Continuation of U.S. application Ser. No. 15/439,261, filed Feb. 22, 2017, now U.S. Pat. No. 10,124,777, which issued on Nov. 13, 2018, the disclosures of which are incorporated by reference herein in their entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     Various types of apparatus have been introduced into the marketplace to provide collision avoidance operation of motor vehicles, principally for collision avoidance of automobiles and light trucks. Most of these systems have been specifically designed for automobiles and light trucks which use hydraulic brake systems. In a hydraulic brake system, brake fluid is used to transmit a hydraulic pressure from the driver&#39;s pedal to the foundation brakes, with or without vacuum assistance to increase the pressure. Braking force is dependent to a large measure upon the pressure developed by pressing the brake pedal. 
     Included in such collision avoidance apparatus are object detection and ranging systems using radar, laser, or optical camera ranging technology to trigger an alarm to the driver, or to adjust the setting of automatic cruise control, or to activate an automated braking system structure. 
     These systems serve to reduce or eliminate the effect of human reaction time in the presence of a collision threat. They are generally intended for OEM, factory installation. 
     Present day collision alarm and avoidance systems usually take the form of a warning system or a supplemental brake control system which is microprocessor driven. Some of these systems prematurely control brake light illumination of a proceeding vehicle, as a distance closure warning to a following vehicle, before the brake pedal of the preceding vehicle is operated. Other systems calculate collision mitigation based upon radar, yaw rate, wheel speed, and rear view camera inputs to control power brake booster performance to adjust braking force in a hydraulic system. Many of these systems have electronic controllers which calculate velocity profiles, collision probabilities and provide supplemental brake system instructions. 
     Braking systems for heavy commercial highway vehicles, such as tractor trailers, heavy straight trucks, and buses, depart from the hydraulic automobile and light truck braking systems, as they are almost exclusively air brake systems. Air brakes can develop a greater stopping force, use simpler components, remain operable even in the presence of a leak, and are generally more safe than hydraulic brakes. Air brakes are found on commercial vehicles with a maximum gross vehicle weight rating (GVWR) of 33,000 pounds or more. They are also often found on vehicles with lesser GVWR, such as 20,000 pounds. 
     Commercial vehicle air brake systems operate with air pressure from air reservoirs containing a volume of high pressure air, ranging from 60 psi to 120 psi (maximum allowed by D.O.T.), depending upon the design of the braking system. Typically, air reservoirs used in air brake systems are under a pressure of 60-120 psi. There generally is a front circuit to operate the front brakes and a rear circuit to operate the rear brakes. Each circuit has its own air reservoir. 
     Fail safe air brake systems provide a lesser pressure to service (work) brakes from a second air reservoir in the presence of a failure in the primary service brake circuit. Other systems utilize a lower pressure circuit to control the relay valves of a higher pressure service brake circuit. 
     Factory available adaptive cruise control systems can electronically set a braking pressure in an air brake system above the default braking pressure, as software resident in the system senses and calculates vehicle factors including speed, yaw rate, lateral acceleration steering angle and traction in regards to predetermined limits for any of these vehicle factors. If the limits are not exceeded, a pressure above the default braking pressure is applied. This process is successively conducted and the pressure is successively increased, based on the successive monitoring and calculating of values in comparison to the predetermined factor limits, until a vehicle deceleration rate of about 2 meters per second is achieved, if possible. Further pressure increases are terminated before the target deceleration rate is achieved if any limit is exceeded. 
     Very high pressure systems have been proposed for disk brake air systems. However, this technology cannot be operatively applied to present air brake circuits, and it is not yet approved by D.O.T. 
     In the past, dual pressure air brake systems have been proposed where a higher pressure (120 psi) is generated by an on-board air compressor and stored in a first tank to operate a spring air brake circuit. Air pressure at 120 psi is passed through a pressure reducing valve to be stored at a lower pressure (60 psi) to operate a service air brake circuit. This technology has no application to collision avoidance circuits. 
     As discussed above, existing collision avoidance systems that have been designed for hydraulic brake systems, are not applicable (transportable) to air brake systems as air brake system components and hydraulic brake system components differ remarkably. The hydraulic system technology is not transportable into air brake system technology. Moreover, existing collision avoidance systems have not been designed for aftermarket installation in older vehicles. Additionally, they have not been designed to operate with various third party warning or detection devices. 
     The National Highway Traffic Safety Administration (NHTSA) and the Insurance Institute for Highway Safety announced in March 2016, that by 2022, 99% of the new automobiles must have automatic emergency braking systems as a standard feature. Automatic emergency braking systems will similarly, also, soon be required for tractor trailers, and heavy straight trucks and buses. 
     The features of aftermarket installation and compatibility with existing third party warning and detection devices are important. 
     It is also important to be able to modify the existing air brake systems on tractor trailers, heavy straight trucks and buses, as these vehicles have long service lives, often extending beyond twenty years or more. These vehicle air brake systems should be able to be modified to meet the new NHTSA standards without replacing the entire air system. 
     It is desirable that the modifications to existing non-electronic air brake systems also be non-electronic, thereby eliminating or minimizing the need for sensitive electronic components. 
     It is further desirable that the modified system be able to operate with drive brake pedal air operation as originally installed. 
     It is also desirable that the system be able to operate with an automatic braking method responsive to an “impending” collision (critical) situation signal, and with an automatic braking method responsive to an “imminent” collision (more critical) situation signal (stage  3 ). 
     It is highly desirable that the modifications of the original air brake system, resident in the present invention, leaves the system pneumatically activated and controlled. 
     SUMMARY OF THE INVENTION 
     An automatic braking control system and method are provided for controlling the automatic operation of an air brake system on a commercial highway vehicle. The system permits the normal manual operation of the air brakes by the driver&#39;s brake pedal, under normal conditions. When a possible collision is detected, the system automatically operates the vehicle&#39;s air braking system to avoid or mitigate the collision. The automatic braking system is pneumatically operated and controlled. 
     The vehicle&#39;s factory installed air braking system, in a normal configuration, is employed to stop the vehicle, such as tractor trailer, a heavy straight truck, or a bus, under the foot-operated brake pedal control of the driver. A commercially available collision warning device is used to detect and calculate an impending collision and/or an imminent collision, whereby the “impending” collision is determined to occur within 1.4 seconds and the “imminent” collision is determined to occur within 0.9 seconds. 
     Where the impending collision automatic braking operation does not stop the vehicle, a second stage operation, i.e., automatic braking for an imminent collision is activated. It is anticipated that the second stage operation will either stop the vehicle or mitigate collision damage. Once the warning device determines a 1.6 second spacing, the collision situation is ended, the automatic activation control ceases, the excess air pressure is bled from the system, and control of the braking is returned entirely to the driver. 
     The commercial collision warning device constantly calculates “closure time”, based upon the speed of the vehicle with collision avoidance, the foregoing (preceding) vehicle&#39;s speed, and the distance between them. 
     The collision warning device is available from such manufacturers as WABCO Holdings, Inc., and Delphi Automotive, Inc. It is a radar-operated, ranging and closure calculating device which is adjusted to generate both the impending collision signal and an imminent collision signal as conditions dictate. 
     The driver is always in control of the braking system and can deactivate the automatic braking function by stepping on the brake pedal or by operating the vehicle turn signals. The commercial collision warning system monitors for and reacts to a change of the driver&#39;s brake pedal position. It also monitors for and reacts to the operation of the vehicle turn signals. 
     The invention provides a modification to a standard air brake system structure, which enables additional automatic activation and control stages. This permits an after-market up-grade of the factory air brake system. For the air brake system on a tractor trailer, an actuation apparatus is connected to a commercial collision warning device having signal nodes mounted on the front of the vehicle. This activation apparatus can be a commercially available, solenoid operated, double acting, two position, four way, valve pair. This element can be an Ingersoll Rand model A 312 SD solenoid operated valve which gets its power from a connection to the collision warning device. 
     The solenoid in the activation apparatus element receives its power from the commercial collision warning device. When the commercial collision warning device detects a change in driver brake pedal position or the activation of the vehicle turn signals, it shuts-off power to the activation apparatus and deactivates the automatic braking operation. 
     The connection between the collision warning device and the actuation apparatus is hard wired. This is the only non-pneumatic connection in the invention&#39;s activation apparatus. The activation apparatus has pneumatic control lines output therefrom. Air pressure is supplied to the actuation apparatus from an air reservoir at its existing pressure, i.e., at 120 psi. 
     A first pneumatic output from this actuation apparatus is connected to operate a delayed application air control connection element positioned in the air pressure line between the front brake control valve and the air control connection for the front brake actuators. A second pneumatic output from the actuation apparatus is connected to operate an immediate application control connection element positioned in the air pressure line between the rear brake control valve and a rear brake relay valve which leads to the rear brake actuators of a tractor and a trailer brake actuators, if a trailer is present. 
     Thus, the system uses high pressure air, at 120 psi, to control the state of certain valves which provide the service air pressure to operate the rear and front service brakes. In controlling the air pressure to the vehicle&#39;s service brakes, the loss of control of the vehicle&#39;s travel path during panic stopping is minimized. Air pressure is always first applied to the rear service brakes, before it is applied to the front service brakes. Air pressure is applied to the front brakes only after (when) a threshold pressure value has been achieved on the rear brakes. Moreover the service air pressure to the rear and front brakes is always controlled so that the rear pressure is always higher than the front pressure. The rear pressure is significantly higher than the front pressure. This assures that the rear brakes are always physically engage before the front brakes and the rear brake stopping force is greater than at the front brakes. This eliminates or minimizes the possibility of a jackknife, or side skidding of the rear of the vehicle. 
     The activation apparatus, a dual operation solenoid valve pair receives air pressure from an air pressure reservoir to be selectively passed into the invention piping in response to signals from the collision warning device. The activation apparatus is normally closed, and provides air pressure at a first output when an impending collision signal is present, and air pressure at second output when an imminent collision signal is present. Only one output of the activation apparatus can be active at a time. 
     When an impending collision signal is received indicating a collision in approximately 1.4 seconds, the activation apparatus component controls valves opening to pressurize the rear foundation brakes to 40 psi, with air from a rear air reservoir. When the air pressure at the rear brakes rises to 20 psi, other valves are controlled to pressurize the front brakes with air from a front air reservoir. This automatic operation stops or slows the vehicle with 40 psi on the rear brakes and 20 psi on the front brakes. 
     When an imminent collision signal is received indicating a collision in approximately 0.9 seconds, the activation component enables valves to open to pressurize the rear brakes to 120 psi with air from the rear air reservoir. When the air pressure at the rear brakes rises to 20 psi, the front brakes are pressurized with air from the front air reservoir. This automatic operation stops the vehicle with 120 psi on the rear brakes and 80 psi on the front brakes, unless restricted to a lower pressure by the brake system manufacturer. For example some air brake equipment can only tolerate lower pressures, such as 80 psi on the rear circuit and 60 psi on the front circuit. 
     By having this braking sequence of the rear service brakes and the front service brakes, the rear tires always want to stop faster than the front tires. This eliminates or minimizes the tendency to fishtail, jackknife or the vehicle rolling over. 
     The present invention provides a modification to a standard air brake system structure, which enables the additional automatic activation and control stages. In the presence of an impending collision signal (1.4 seconds closure) the activation component opens valves to pressurize the rear service brakes are pressurized to about 40 psi, with air from a rear air reservoir. When the air pressure at the rear brakes rises to about 20 psi, other valves are opened to pressurize the front brakes with air from a front air reservoir. This automatic operation stops or slows the vehicle with about 40 psi on the rear brakes and about 20 psi on the front brakes. In the presence of an imminent collision signal (0.9 seconds closure), the activation component enables valves to open to pressurize the rear brakes to about 120 psi with air from the rear air reservoir. When the air pressure at the rear brakes rises to about 20 psi, the front brakes are pressurized with air from the front air reservoir to about 20 psi. Thus, this automatic operation stops the vehicle with about 120 psi on the rear brakes and about 80 psi on the front brakes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be understood from a reading of the following description and the attached claims, in connection with the accompanying drawings, in which like numerals refer to like elements and in which: 
         FIG. 1  is a block diagram for the invention system; 
         FIG. 2  shows the braking distance curve for an air brake system operating normally, with manual brake actuation from brake pedal operation; 
         FIG. 3  shows the braking distance curve with automatic brake actuation of the present invention; and 
         FIG. 4  shows the braking distance curve of the invention when coupled with an optional electromagnetic retarder on the drive shaft or on a rear axle. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is a pneumatically operated and pneumatically controlled automatic braking control system and method for controlling air brakes on a commercial highway vehicle. The system operates in multiple stages. There is normal manual operation of the air brakes by the driver&#39;s brake pedal under normal conditions. When a possible collision is detected, the system automatically operates the vehicle&#39;s air braking system, by first applying air pressure to the rear brakes. When the pressure at the rear brakes has reached 20 psi, air pressure is applied to the front brakes. The air pressure applied on the rear brakes is ultimately 40 psi, and on the front brakes is ultimately 20 psi. 
     In a next stage, air pressure is also first applied to the rear brakes. When the rear brake pressure reaches 20 psi, air pressure is fed to the front brakes. In this stage, the air pressure on the rear brakes is ultimately 120 psi and on the front brakes is 80 psi. These pressures are reduced when required by the manufacturer&#39;s specifications. 
     The initial stage is activated when the vehicle is calculated to be approximately 1.4 seconds from impact. The next stage is activated when the vehicle is calculated to be approximately 0.9 seconds from impact. 
       FIG. 1  shows a block diagram of the structure of the invention. In a driver operated mode, a driver operated brake pedal  21  operates a rear brakes control valve  23  and a front brakes control valve  25 , concurrently. The rear brake control valve  23  receives air pressure from a rear air reservoir  45  via a pneumatic line  44 . The front brake control valve  25  receives air pressure from a front air reservoir  29  via a pneumatic line  31 . 
     The output from the rear brake control valve  23  is connected to a rear service brake relay valve  51  via pneumatic line  52 . Rear relay valve  51  then passes air pressure onto a left and a right rear ABS module  55 ,  57  via pneumatic line  53 . The left and right rear ABS modules  55 ,  57  respectively feed left and right tandem brake actuators  59 ,  61 . 
     The rear relay valve  51  via an additional pneumatic line  70  passes air pressure through a tractor protection valve  75  to a trailer service brake line  77 , if a trailer is present. 
     The output from the front brake control valve  25  is connected to a front “T” connector gate  36  though a pneumatic line  81 . Front connector gate  36  passes air pressure to a left and a right ABS module  37 ,  39  via a pneumatic line  40 . Left and right ABS modules  37 ,  39  feed air pressure to left and right front brake actuators  41 ,  43 , respectively. 
     A commercial warning device  11  is employed to detect collision conditions and to send signals indicating one or the other of two collision conditions, “impending” or “imminent”. The output from the warning device  11  is three electrical wires  15 , a “high” signal, a “low” signal and a ground. The low signal indicates an impending collision. The high signal indicates an imminent collision. No signal indicates a non-collision situation. Electrical connection cabling  15  powers (i.e., drives) an actuation apparatus  13 , which actuator is an electronic, two stage, solenoid operated, air valve. The actuation apparatus  11  has two outputs. The first output is connected to a pneumatic line  19 , while the second output is connected to a pneumatic line  79 . 
     An “impending” collision (i.e., closure) indicates a collision in 1.4 seconds. An “imminent” collision indicates a collision (i.e., closure) indicates a collision in 0.90 seconds. A closure equal to or greater than 1.6 seconds is a non-collision condition. 
     The air pressure in the front air reservoir  29  is about 120 psi. The air pressure in the rear air reservoir is also kept at about 120 psi. Pneumatic line  49  feeds the 120 psi pressure to the actuation apparatus  11 , which in turn feeds a one-way connector gate  71 , via the pneumatic line  19 . A pneumatic line  85  exits the one-way gate  71  and connects to a pressure regulator, step down gate  69 . Regulator gate  69  can be adjustable. Regardless, it reduces the 120 psi from the actuation apparatus  11  to a pressure of 40 psi. The output of regulator gate  69  is connected to a connection “T” gate  83 . An output line  84  from gate  83  is connected into a crack valve  36 . The output of the crack valve  35  is connected into the front “T” connector gate  36  to ultimately lead to the front brake actuators  37 ,  39 . The crack valve  35  operation may be adjustable. The crack valve  35  of the present invention is set to quickly release (open) at 20 psi. 
     Another pneumatic line from the “T” connection gate  83  is connected into a “T” connection gate  73 . A pneumatic line from gate  73  connects to a connector “T” gate  65  via a pneumatic line  72 . The gate  73  is also connected to an output from the rear brake control valve  23 . The second output from the actuation device  11  via a pneumatic line  79  connects with the connector gate  79  which is connected to the input  67  of the rear relay valve  51  via a pneumatic line  63 . 
     Air pressure is output from the actuation apparatus  11  via line  19  in an “impending” collision condition, i.e., where there is about 1.4 seconds of closure time until impact. In this situation there is no air pressure on line  79  from the other output actuator  11 . 
     Air pressure is output from the actuation apparatus  11  via line  79  in an “imminent” collision condition, i.e., where there is about 0.9 seconds of closure time until impact. In this situation there is no air pressure on line  19  from the other output from actuator  11 . 
     As an option, an electro-magnetic retarder device may be added, to be mounted to a rear axle or to the drive shaft to contribute additional braking action. Such retarders are frictionless stopping aids which are used to slow vehicles to prevent the service brakes from overheating and to minimize stopping distance. Retarders are commercially available from such manufacturers as Frenelsa S.A., Telma, S.A., Cama Products, Kimbo/Sharp Corporation and others. 
     When 1.4 seconds to impact is detected, the invention sends air pressure from rear reservoir  45  through the actuator  11 ,  FIG. 1 . Then via line  19  though gate  71 , via line  85 , through gate  69 , through regulator  69 , though gate  83 , and via line  84  to wait for crack valve  35 . 
     Air pressure also flows though gate  83 , through gate  73 , via line  72  to gate  65 , and there through. The air pressure travels via line  63  to input  67  and through relay gate  51  to the rear brakes. The other output from actuator  11  is closed. 
     When the pressure at the rear brakes relay valve  51  rises to 20 psi, there is also 20 psi at the crack valve  35 . Crack valve  35  then opens and air pressure begins to build on the front brakes as it continues to increase on the rear brakes. The rear brake pressure is higher than the front brake pressure and remains so. The pressure is held with 40 psi on the rear brakes and 20 psi on the front brakes to stop the vehicle. When a trailer is present, trailer brake pressure will approximate the rear brake pressure at 40 psi. 
     When 0.9 seconds to impact is detected, the invention send air pressure from rear reservoir  45  through the actuator  11 , and then via line  79  to the gate  65 . The other output port from actuator  11  is closed. 
     The pressure at gate  65  is sent via line  63  to the rear relay valve  51  and via line  72  to gate  73 . From gate  73  the pressure passes through the gate  83  and then via line  84  to the crack valve. When the pressure at the crack valve rises to 20 psi the crack valve opens and pressure begins to build on the front brakes, while continuing to rise on the rear brakes. The rear brake pressure is higher that the front brake pressure and remains so. A pressure of 120 psi is held on the rear brakes and 80-100 psi on the front brakes to stop or slow the vehicle. Again, when a trailer is present, the trail brake pressure will follow the rear brake pressure at 120 psi. 
     The operation of the invention, including following distance, response time and vehicle speed, is shown in  FIG. 3 , and can be compared with the same factors for the operation of a manual braking system,  FIG. 2 , and the same factors for the operation of the invention coupled with a commercial electro-magnetic retarder mounted to the vehicle drive shaft, or rear axle. These graphs were generated from test results obtained by operating the same test vehicle, which was first-operated with manual braking, then, secondly, with the collision avoidance braking invention in place, and lastly, with a drive shaft mounted retarder or rear axle mounted retarder added to the invention. 
     In each of these graphs ( FIGS. 2, 3, 4 ) the solid line  87  shows vehicle following distance. Each of the graphs show a closure, i.e., a reduction in following distance of the test vehicle with respect to a preceding vehicle. For the manual system,  FIG. 2 , the response time, once a collision warning is generated, is shown as time of driver collision recognition  91 , driver response  93 , and brake response  95 . For the present invention,  FIG. 3 , the response time once a warning is generated, is indicated by brake response  95  followed by brake deceleration  97 . It is important to note that brake deceleration  97  is shown to occur much sooner in  FIGS. 4 and 5 , than in  FIG. 3 . 
     The next important factor to note is the time of closest vehicle approach 99. This is the demarcation point, where the test vehicle braking action results in an increase in the distance to the foregoing vehicle, thereby avoiding a collision. This factor relates to the speed curve  101  of the braking vehicle which shows a reduction in speed  101 ,  FIGS. 2, 3, 4 , during braking. This speed reduction is seen to occur soonest in  FIG. 4 . The time to speed reduction is seen to be slightly less in  FIG. 3 .  FIG. 2  shows the largest delay before a speed reduction occurs. 
     Once braking has occurred, the driver must make an evaluation  103 . The driver controls the acceleration  105  of the vehicle  105  if conditions warrant. Once a safe distance is achieved  107 , driver acceleration is ended  109 . 
     With manual braking,  FIG. 2 , the warning duration  111  extends from the start of the warning signal  89  to the time a safe distance is achieved  107 . With the invention,  FIG. 3 , the warning duration  111 , is less, as it extends from the start of the warning signal  89  to the achievement of a safe distance  107  at the beginning of driver evaluation  103 . 
     With the addition of an electro-magnetic retarder,  FIG. 4 , warning duration  111  is further shortened and additional braking improvement  113  occurs. This improvement  113  is shown as the time from the achieved safe distance  107  time, to the time almost to the termination of driver controlled acceleration  109 . 
     The following elements are shown in the accompanying drawings.
       11  collision warning device     13  actuation apparatus—electronic, two stage, solenoid operated, air valve     15  electrical connection cabling—HLG (high low ground) cable wire     19  pneumatic line from actuation apparatus  11  to gate  71       21  driver brake pedal     23  rear brakes control valve     25  front brakes control valve     29  front air reservoir     31  pneumatic line from front air reservoir  29  to front brakes control valve  25       35  quick release crack valve     36  front “T” connector gate     37  left front ABS     39  right front ABS     40  pneumatic line from connector gate  36  to ABS  37  and  39       41  left front actuator     43  right front actuator     44  pneumatic line from rear air reservoir to rear control valve  23       45  rear air reservoir     47  air supply connector     50  pneumatic line from rear brake control valve  25  to relay valve  51       51  service brake relay valve     53  pneumatic output to rear ABS  55  and  57       55  left rear ABS     57  right rear ABS     59  left rear brake actuator     61  right rear brake actuator     63  pneumatic feed from gate  65  to rear relay valve input  67       65  connector “T” gate     67  input for rear relay valve  51       69  pressure regulator step down gate 120 psi to 40 psi     70  pneumatic line from rear relay valve to tractor protection valve  75       71  one-way connector gate     72  pneumatic line from gate  73  to gate  65       73  pneumatic “T” connection gate between gate  83  and rear control valve  23       75  tractor protection valve     77  trailer service brake line     79  pneumatic line from activation apparatus  11  to connector gate  65       81  pneumatic line from front brake control valve  25  to front “T” connector gate  36 , which   connector gate also is connected to the output from crack valve  35       83  pneumatic connection “T” gate from pressure reducer  69       84  pneumatic line from gate  83  to crack valve  35       85  pneumatic line from one-way gate  71  to pressure reducer  69       87  solid line following distance     89  collision warning     91  driver recognition     93  driver response     95  brake response     97  brake deceleration     99  time of closest approach     101  speed curve     103  driver evaluation     105  driver acceleration     107  safe distance achieved     109  acceleration ended     111  warning duration     113  improvement in braking   

     The foregoing description is intended to be illustrative of the invention. Modifications and substitutions may be introduced without departing from the scope or intent of the described invention or the accompanying claims.