Air bag system for automobiles
BACKGROUND 
     Air bags are a well-known means to protect occupants of vehicles in front-end collisions. The most common types of air bags are inflated irreversably and very rapidly by chemical means. A malfunction in the inflation control apparatus may trigger inflation during normal driving and cause a crash. It is desirable to provide an air bag which begins inflation at a slower rate in advance of actual collision in response to brake pressure, but is also actuable by harness tension or bumper impact, and is readily deflatable. 
     BRIEF SUMMARY 
     An air bag is stored in a tapered open container facing the front seat of a car. Compressed air for its inflation is stored in a tank on the vehicle. The tank has an external valve stem, through which it may be initially filled at a service station. A small piston pump operated by the normal repeated use of the brake pedal keeps up the pressure in the tank. 
     In the hydraulic brake line, a pressure switch responds to excessive brake pedal pressure which signals an emergency situation. The pressure switch energizes a solenoid air valve which admits compressed air from the tank into the air bag at a rate to inflate the bag at a moderate rate, for exambple 1 to 3 seconds to fill it. If the emergency situation does not mature into a crash, the driver has time to deflate the bag by operating a manual switch. The switch controls an electric deflation pump. Pulleys on the pump shaft wind up cords attached to the bag, pulling it back into its tapered container as it deflates. 
     The air bag is also inflated in response to (1) force against the front bumper closing a bumper switch, and (2) excessive tension in the seat belt or shoulder harness. A pully--with wheel type pully could allow the air to be drawn back into the air tank while rolling the bag into place. 
    
    
     DETAILED DESCRIPTION 
     IN THE DRAWINGS: 
     FIG. 1 is a side diagrammatic view of an automobile showing the elements of the invention; 
     FIG. 2 is a perspective view of a car passenger compartment showing a harness switch; 
     FIG. 3 is a partial cutaway perspective view showing elements of the system; 
     FIG. 4 is a top sectional view showing the air bag and its container; and 
     FIG. 5 is a diagram of a hydraulic brake and air bag control system. 
    
    
     In FIG. 1, the brake pedal is shown at 2, the air tank at 3, the retracting pulleys or drums at 4, and air bag at 5. A brake switch is indicated at 6, a bumper switch at 7, and a shoulder harness switch at 8. All three switches are connected to air valve 16, a solenoid valve that admits air from tank 3 into bag 5. 
     FIG. 2 shows the harness switch 8 in more detail. Excessive tension operates contacts which are connected by leads 38 to solenoid valve 6 via the car battery (not shown). 
     In FIGS. 3-5 a conventional brake pedal 2 and master cylinder 53 are connected to a conventional hydraulic brake system through brake lines 50. One of the brakes is indicated at 51. An additional hydraulic line 52 leads to an air pump 61 and brake switch 6. Air pump 61 is of known piston construction with a check valve 62 and an inlet 63. A hydraulic piston 64 is moved to the left in response to normal brake line pressure in normal driving; a suitable air piston at its end cyclically compresses air drawn from inlet 63 and forces it into tank 3 via the check valve 62, keeping up the tank pressure. A valve stem 18 is provided for initially filling the air tank, as at a service station, in the manner of a tire. 
     Also connected to hydraulic line 52 is brake switch 6, which may be of any suitable construction designed to respond to excessive pressure on the brake pedal 2, well beyond the pressures found in normal driving. Leads 70 go to the car battery, not shown. Leads 71 go to a solenoid-operated air valve 30. When brake switch 6 is closed, valve 30 opens and admits air from tank 30 into line 31, which goes to air bag 5 (FIG. 3). 
     Also connected to the solenoid valve leads 72, FIG. 5, are the shoulder harness switch 8 via its leads 38 (FIG. 2) and the bumper switch 7 (FIG. 1) via its leads 73, in a manner to open the valve 30 in response to excessive harness tension or to bumper impact. 
     The deflation system is shown best in FIGS. 3-4. A manual switch 9, which may be on the instrument panel, energizes an electric pump motor 13 via leads 39. Pump 14, of any suitable construction, is driven by the motor. Pump 14 has inlet and outlet connections to solenoid valve 30 connected in a suitable way to deflate the air bag. Pump 14 may pump the air back into tank 3, or alternatively may discharge it to the atmosphere. 
     Pulleys or drums 4 on the motor shaft, shown best in FIG. 4, are arranged to wind up cords 15 which are attached to air bag 5, so as to draw it mechanically back into its container 17 as it deflates. Container 17 is tapered toward the back to facilitate the re-entrance of the deflated bag.