Measuring and testing – Testing by impact or shock – Accelerated or decelerated specimen
Reexamination Certificate
2001-08-31
2003-07-29
Kwok, Helen (Department: 2856)
Measuring and testing
Testing by impact or shock
Accelerated or decelerated specimen
C073S865300
Reexamination Certificate
active
06598456
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains generally to the control of the acceleration pulse delivered by HYGE (Hydraulically Controlled, Gas Energized) crash simulation sleds used in safety testing of vehicle components.
BACKGROUND OF THE INVENTION
The HYGE (Hydraulically Controlled, Gas Energized) system derives its powerful thrust force from an actuator assembly
1
which uses differential gas pressure acting on the two faces of a thrust piston
10
in a closed cylinder
12
, as shown in FIG.
1
. The cylinder is separated into two chambers A, B by an orifice plate
14
. A relatively low gas pressure in chamber A, known as the Set Cylinder, forces the thrust piston
10
against a seal ring
16
on the orifice plate
17
. The area of the entire thrust piston face is exposed to the gas pressure in chamber A, defined by floating pistons
26
opposed to thrust piston
10
. On the other side of the piston, only the small area within the seal is exposed, through the orifice opening, to the gas pressure in chamber B, known as the Load Cylinder, in which a floating piston
24
is located.
In preparation for firing, compressed gas is introduced into the Load Cylinder until the forces on the thrust piston
10
are equalized. To fire the piston, a small burst of compressed gas is introduced into the trigger chamber
18
, which is the small area within the seal on the chamber B side of the piston. This burst upsets the equilibrium, opening the seal at the orifice plate
17
and exposing the entire surface area of the piston to the the seal at the orifice plate
17
and exposing the entire surface area of the piston to the higher pressure in the Load Cylinder. This results in a powerful thrust force being applied to the thrust piston in the direction of chamber A. This thrust force is then transmitted to a crash sled through the thrust column
20
.
The thrust force has, until now, been controlled by regulating the compressed gas flow through the orifice plate by the shape of the metering pin
22
, which is progressively drawn through the orifice as the metering pin, thrust piston, and thrust column assembly move in the direction of chamber A during the firing event.
The HYGE (Hydraulically Controlled, Gas Energized) reaction simulates the longitudinal deceleration conditions of an impact, but in reverse. Prior to an actual crash, the test vehicle and test dummies each move at a constant velocity. At impact, they are stopped very rapidly. During a HYGE (Hydraulically Controlled, Gas Energized) crash simulation sled test, the test vehicle and dummies, which are attached to the sled, are initially at zero velocity. This situation simulates the constant velocity condition prior to an actual crash. The metering pin programmed acceleration of the HYGE (Hydraulically Controlled, Gas Energized) sled drives an automobile assembly attached to the crash sled, which is shown in
FIG. 2
, out from under the test dummies, producing a response similar to that caused by the rapid deceleration of a moving vehicle. The acceleration and deceleration effects are interchangeable because the acceleration—time relationships are the same in both cases.
The metering pin controlled force output works well, but is cumbersome and time-consuming to change to another force—time profile, requiring disassembly of the Set and Load Cylinders and removal and insertion of a different-shaped metering pin. A large inventory of such metering pins may be required in order to represent all the force—time shapes required.
SUMMARY OF THE INVENTION
Control of the force—time relationship during actuator motion is possible by other means than just metering pin shape. Instead of allowing all the force applied to the thrust piston to be directly applied to the thrust column and then used to accelerate the sled, an electronically controlled force control device may be employed to control the amount of force being made available to accelerate the sled.
Such an acceleration control (accelerator) device may take the form of a brake or force actuator acting in parallel with the HYGE (Hydraulically Controlled, Gas Energized) actuator to provide a force-path to ground either in parallel with the sled, or a force generator/absorber in parallel with the HYGE (Hydraulically Controlled, Gas Energized) actuator. This parallel accelerator device is to be closed-loop controlled using sled acceleration as the feedback signal source to compare with the desired acceleration value at a sequence of time increments and to apply a corresponding acceleration output to the sled or HYGE (Hydraulically Controlled, Gas Energized) actuator to drive the acceleration error (difference between desired and actual acceleration) toward zero, thus achieving true closed-loop control over the acceleration—time pulse during the actuator firing event.
REFERENCES:
patent: 3739625 (1973-06-01), Roberts et al.
patent: 4648490 (1987-03-01), Bergloff
patent: 5245856 (1993-09-01), Pazzaglia et al.
patent: 5483845 (1996-01-01), Stein et al.
patent: 5485758 (1996-01-01), Brown et al.
patent: 5929348 (1999-07-01), Stein et al.
Stein et al., U.S. patent application 2002/0121144 A1, Sep. 5, 2002.
Garber C D
Kwok Helen
Roetzel & Andress
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