BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a highly schematic view of a safety device incorporating the inventive gas spring.
FIG. 2A shows the gas spring having a pressure switch in a normal position.
FIG. 2B shows the position of the components of the pressure switch when the pressure within the gas spring has fallen.
FIG. 3 schematically shows further details of the inventive pressure switch.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A safety system 20 is illustrated in FIG. 1. A hood 22 of a vehicle includes a forward end 25 and a rear end 23. The hood 22 typically pivots from the rear end 23 such that the forward end 25 provides access to an engine compartment. In a feature of this invention, a crash sensor 24 is positioned near the forward end 25 of the vehicle. If the crash sensor 24 determines that the vehicle has contacted a pedestrian, then a gas spring 26 (or several gas springs) are actuated to drive a piston 34 to move outwardly against a connection 28 to the hood 22. This causes the hood 22 to pivot about the forward end 25 such that the rear end 23 raises to cushion impact of the pedestrian.
In one example, a solenoid controlled pin 100 holds piston 34 at a compressed position. Pin 100 is released when a front pedestrian impact is detected by sensor 24. This drives the hood 22 to the position shown in phantom at 200.
Typically, the hood 22 would be able to move during normal operation to provide access to the engine compartment without any movement of the portion driven by the gas spring 26. The connection of all of these components may be as known, and forms no portion of this invention.
Another end 30 of the gas spring 26 is connected to a vehicle frame at 32. The piston 34 is movable within a housing providing a cylinder 37. A chamber 36 within the cylinder 37 is provided with a charge of compressed gas. A pressure switch 38 has a pin 40 extending into the chamber 36.
As shown in FIG. 2A, the pin 40 is biased out of the chamber 36 by a pressure P in the chamber 36. In opposition, a spring 42 forces a cap 44, movable with the pin 40, back into the chamber 36. The spring 42 is sized such that if the chamber 36 is properly charged, the pin 40 will be held in the position illustrated in FIG. 2A.
A seal 46 seals the chamber 36 at an opening through which the pin 40 moves. A guide 48 guides the movement of the cap 44. An end 50 of a housing 52 for the pressure switch 38 is connected to the cylinder 37.
A lower end 54 of the pin 40 is received between fingers 58. The pin 40, at least at its end 54, and the fingers 58, are electrically conductive. Thus, as long as the pin 40 remains in the FIG. 2A position, a circuit is created between the two fingers 58 which are connected by the end 54. Fingers 58 connect to members 56 which in turn are connected to terminals 60.
As shown in FIG. 3, terminals 60 extend to an electrical power and control 62. As known, a small voltage can be sent through this circuit, and control 62 can monitor that the circuit is maintained. A warning, such as an audible signal, or some form of warning light 64 can be placed on a dash of a vehicle.
As shown in FIG. 2B, should the pressure within the chamber 36 fall, then the pin 40 can move under the influence of the spring 42, and the circuit between the lower end 54 and the fingers 58 is broken. At that point, the warning light 64 can be actuated.
The present invention thus provides a relatively simple way of monitoring the continued operability of a gas spring.
Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
Patent Application
20080012187
