US2639913A - Crash decelerator - Google Patents

Description

May 26, 1953 REYNOLDS 2,639,913

CRASH DECELERATOR FilEd April 10, 1950 j gai a7 34 INVENTOR. LEE 7" REY/V0105 ATTORNEY Patented May 26, 1953 CRASH DECELERATOR Lee T. Reynolds, West Los Angeles, Calif., as-

signor, by direct and mesne assignments, to Reynolds Decelerator Company, a copartnership Application April 10, 1950, Serial No. 155,091

Claims.

This invention relates to a decelerating device or shock absorber and is more particularly designed for use in air craft for reducing the hazards of crash injuries to air craft pilots.

The principal object of the invention is to provide a device of this character which can be conveniently attached to the body harness of a pilot and which will act to efilciently and safely decelerate the pilot under ordinarily fatal and damaging crash conditions.

Springs and elastic harnesses have been pro posed for the purpose of deceleration. These devices have not been satisfactory as they only serve to store the energy created by the inertia of the pilots body and to return this energy as recoil which is as damaging as the original motivating shock would have been. Another object of this invention is to provide a decelerating device in which all recoil will be eliminated.

A further object is to so construct the device that the cushioning effect and time interval obtainable from a long cushioning spring can be attained in a relatively short distance.

Other objects and advantages reside in the detail construction of the invention, which is designed for simplicity, economy, and eifici'ency. These will become more apparent from the following description.

In the following detailed description of the invention, reference is had to the accompanying drawing which forms a part hereof. Like numerals refer to like parts in all views of the drawing and throughout the description.

In the drawing:

Fig. 1 is a longitudinal section through the improved decelerating shock absorber illustrating the elements thereof in the static or unstressed position;

Fig. 2 is a similar section illustrating the elements in a shock absorbing position;

Figs. 3 and 4 are cross-sectional views taken on the lines 3-3 and l-G, respectively, of Fig. l; and

Fig. 5 illustrates the application of the invention to a typical air craft pilots harness.

While the invention is more particularly designed to be used to relieve crash shocks on an air craft pilot, it will be equally valuable for the drivers of racing cars, for relieving parachute shocks when jumping from high speed planes, etc.

In Fig. 5 the improved device is illustrated connected between the harness ID of a pilot H and his seat 12. The harness H] is provided with attachment loops 13 to which the improved de- 2 celerating devices are attached by means of her ness hooks It. The devices are provided with a, second hook 25 for attachment to the seat I2. Two of the devices are used with each harness, one at each side of the seat l2.

The improved decelerating device is enclosed in an outer tubular housing 16, one extremity of which is closed by a threaded cap H, the other extremity being open. An internal partition I8 is formed in the housing l6 adjacent the capped extremity thereof.

The inner extremity of a hydraulic cylinder I9 is threaded concentrically into the partition IS. The cylinder I9 is of less diameter than the internal diameter of the housing 16 so as to form a cylindrical-shaped fluid chamber 20 about the cylinder It. The outer extremity of the cylinder I9 is closed by the capll.

A relatively large slotted fluid return port 2| communicates between the interior of the cyl inder I9 and the chamber 20 adjacent the outer extremity of the former and a plurality of aligned, spaced-apart smaller ports 22 communicate between the chamber 20 and the cylinder I9. throughout the length of the latter. In use, the cylinder 19 and the chamber 29 are completely filled with light cylinder oil or a suitable hydraulic brake fluid.

The piston rod 23 extends through the partition 18 into the cylinder i9 where it is threaded,- as shown at 25, into a piston 24. The pistonis sealed to the wall of the cylinder by any suitable pressure expansible packing and the piston rod 23 is sealed to the partition i8 by similar packing 26.

A compression spring 21, within the cylinder 19, constantly urges the piston 2 1 towards the outer end of the cylinder 19. A shear pin 28 extends into the cylinder l9 and into th piston 24 to resist inward movement of the latter. The strength and size of the pin 28 is such that it will be sheared ofi by the piston 24 when subjected to a minor pull of say 500 pounds.

The inner extremity of the piston rod 23 is threaded or otherwise secured in a first head member 23. A ratchet barrel 3B is secured'in, and extends from, the first head member 28, to a second head member 3|. The two head menibers 29 and 3| are slidable in the open extremity of the housing l6. v

A spring sleeve 32 projects through the second head member 3i and is closed at its projecting extremity by means of a threaded cap 33 from which the harness hook i l projects. A tension spring 34 is positioned within the spring sleeve 32 and is secured at its one extremity to the head member 29 and at its other extremity to the cap 33.

A toothed ratchet rack 35 is fixedly mounted in the barrel 30 at one side thereof and an annular ratchet flange 36 is formed about the extremity of the sleeve 32 within the barrel. A leaf spring 31 is mounted in the barrel 30 at the side opposite to the ratchet rack 35. The spring 31 bears against the spring sleeve 32 so as to constantly urge the latter toward the ratchet rack 35.

The strength of the spring 34 and the size of the ports 22 are predetermined depending upon the particular use and installation. As an example, for air craft work the ports 22 may be such as will enable the piston 24 to travel the full length of the cylinder l9, against the action of the spring 21, in approximately /20 of a sec nd and the spring 34 will be of a strength to require a 2500 pound pull to cause the ratchet flange 36 to travel the full length of barrel 30.

Now let us assume that a pilot weighs 200 lbs. and that a crash or deceleration is encountered of 40 G. magnitude. This will apply an instant load on both devices of 8000 pounds or 4000 pounds on each device. If the barrel 30 were held stationary, this load would snap the ratchet flange 36 of each device instantly against the second head member 3| subjecting the pilot to an impact of 3000 pounds, since only 2500 pounds would be absorbed by each spring.

However, the barrel 30 is not permanently stationary for the instant the pull of the spring 34, in each device reaches 500 pounds, the pin 28 will shear, releasing the piston 24. A very small fraction of a second later the inertia of the fluid in the cylinder l9 will be overcome and the piston 24 will move inward in the cylinder l9-at a decelerating rate, due to the successive closing of the discharge ports 22. This allows .the head member 29 to move with the spring sleeve 32 and at a slower rate than the latter so as to delay the time when the spring sleeve will be fully extended from say /1000 of a second to /20 of a second and giving the effect of a much longerand lighter spring.

All of the above actions occur while the ratchet flange 36 is approaching the ever moving second head member 3] and all of this action is ab sorbing energy from the-original 4000 pound shock on each device. By the time the flange 36 reaches the head 3|, provided the shock is great enough to move it this far, and by the time the piston 24 reaches the partition I 8 /20 of a second) very little energy, if any, will remain for transmission to the seat hook l and the shock peak will have been passed.

For example let us assume that in each device 500 pounds will be absorbed at the closing of each port 22 so that after five ports have closed, the fluid will have absorbed approximately 2500 pounds of the original pull which, plus the 500 pounds required for pin shearing and 500 pounds required for overcoming the inertia of the fluid, leaves only 500 pounds to be absorbed by the spring 34. This will move the ratchet flange 36 only a few notches down the ratchet rack 35 where it will be held against recoil.

One of the principal purposes of the shear pin 28 is to prevent the piston from being displaced from the end of the cylinder [9 under the pull and stress of fitting the harness and devices to 4 the pilot and under the normal movements of the pilot on his seat.

Since the major deceleration action is obtained from the hydraulic elements of the device, the spring 3'4 serves principally to relieve the initial shocks of shearing the pin and overcoming the staticinertia of the hydraulic fluid.

After the shock peak is passed, the spring 21, the shock absorbing qualities of which have been ignored in the above discussion, will return the piston 24 to its original position forcing the fluid from the outer end of the cylinder back through the port 2|, the chamber 20, and the ports 22 to the inner end of the cylinder [9.

The ratchet flange 36 can be released from the ratchet rack 35 by simply prying the hook I 4 upward to force theinner extremity of the sleeve 32 downward.

While a specific form of the improvement has been described and illustrated herein, it is to be understood that the same may be varied, Within the scope of the appended claims, without departing from the spirit of the invention.

Having thus .described the'invention, what is claimed and desired secured by Letters Patent is:

1. A decelerating device comprising: a plunger; a barrel enclosing said plunger, said plunger projecting from one extremity of said barrel; a tension spring securing said plunger to the other extremity of said barrel to resist withdrawal of the former and a longitudinally extending series of ratchet teeth in said barrel positioned to be engaged by said plunger for preventing return of the plunger after withdrawal thereof; and resilient means urging said plunger sidewardly into engagement with said ratchet device.

2. A decelerating device comprising: a barrel; a plunger Withdrawable from said barrel; a spring positioned in said barrel and acting be tween said barrel and said plunger so as to re sist withdrawal of said plunger from said barrel; a fluid cylinder; a piston in said cylinder, said cylinder being positioned in an axial alignment with said -barrel;. a piston rod rigidly connecting said barrel to said piston; fluid in said cylinder, there being fluid ports in said cylinder allowing the fluid to escape from ahead of said piston as said connecting means urges said piston forwardly.

- 3. A decelerating device comprising: a barrel; a plunger withdrawable from said barrel; a spring positioned in said barrel and acting between said barrel and said plunger so as to resist withdrawal of said plunger from said barrel; a fluid cylinder; a piston in said cylinder, said cylinder being positioned in an axial alignment with said barrel; a piston rod rigidly connecting said barrel to said piston; fluid in said cylinder, there being fluid ports in said cylinder allowing the fluid to escape from ahead of said piston as said connecting means urges said piston forwardly; and an outer casing maintaining said barrel in axial alignment with said cylinder.

4. A decelerating device comprising: a barrel; a plunger withdrawable from said barrel; a spring positioned in said barrel and acting between said barrel and said plunger so as to resist withdrawal ofsaid plunger from said barrel; a fluid cylinder; a piston in said cylinder, said cylinder being positioned in an axial alignment with said barrel; a piston rod rigidly connecting said barrel to said piston; fluid in said cylinder, there being fluid ports in said cylinder allowing the fluid to escape from ahead of said piston as said connecting means urges said piston forwardly; and return resisting means between said barrel and said plunger and acting to resist the return of said plunger to said barrel.

5. A decelerating device comprising in combination: a tension spring; a fluid cylinder; a piston in said cylinder; means connecting said spring at its one extremity with said piston; attachment means for connecting said cylinder to a support; a second attachment means for connecting said spring at its other extremity to a device to be decelerated; and mechanical ratchet means positioned between said second attachment means and said piston for preventing return reaction of said spring.

' LEE T. REYNOLDS.

References Cited in the file of this patent UNITED STATES PATENTS Number Number

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