US3631760A

US3631760A - Pneumatic torpedo launcher with hydraulic operated snubber

Info

Publication number: US3631760A
Application number: US882566A
Authority: US
Inventors: Stephen F Moran
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1969-12-05
Filing date: 1969-12-05
Publication date: 1972-01-04
Anticipated expiration: 1989-01-04

Abstract

Short power strokes of the ram of a catapult are obtained by high-pressure air, and the snubbing action for stopping and returning the ram is by high-pressure oil. An exhaust port in the cylinder and a floating sleeve valve marks the end of the power stroke and the beginning of the ram deceleration. Snubbing is against a cushion of oil placed end-to-end with a cushion of air. The system is closed so that no tell-tale air bubbles escape.

Description

United States Patent l l I 1 1 1 1 1 Stephen F. Moran San Diego, Calif.

Dec. 5, 1969 Jan. 4, 1972 The United States of America as represented by the Secretary of the Navy Inventor Appl. No. Filed Patented Assignee PNEUMATIC TORPEDO LAUNCHER WITH HYDRAULIC OPERATED SNUBBER 6 Claims, 2 Drawing Figs.

US. Cl 91/402, 92/65, 92/134, 92/143 Int. Cl ..Fl5b 15/22, FOlb 7/10 Field of Search srop e DECELERATION T AccELEnAT|o-47o| [56] References Cited UNITED STATES PATENTS 2,415,783 2/1947 Bassett et al 92/65 2,708,908 5/1955 Taylor 91/402 3,162,578 12/1964 Allen 91/402 3,278,154 10/1966 Gundersen 92/143 3,531,065 9/1970 Brown 91/402 Primary ExaminerPaul E. Maslousky Attorneys -R. S. Sciascia, G. J. Rubens, J. W. McLaren and T.

L. Styner ABSTRACT: Short power strokes of the ram of a catapult are obtained by high-pressure air, and the snubbing action for stopping and returning the ram is by high-pressure oil. An exhaust port in the cylinder and a floating sleeve valve marks the end of the power stroke and the beginning of the ram deceleration. Snubbing is against a cushion of oil placed endto-end with a cushion of air. The system is closed so that no tell-tale air bubbles escape.

PATENTEUJAN M972 3631; 760

/2 @vx q I V 4-- FlRING VALVE a- IZ PUMP ACCELERATION TA STOR STOP -94 DECELERATION INVENTOR.

STEPHEN E MORAN B r y ATTORNEYS PNEUMATIC TORPEDO LAUNCHER WITH HYDRAULIC OPERATED SNUBBER STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefore.

BACKGROUND OF THE INVENTION A catapult has been designed to launch torpedoes from torpedo tubes placed around the hull of a moving submarine. This launcher requires a pneumatic cylinder and ram to accelerate the sled" which holds the torpedo in the line with the tube. At the end of the acceleration stroke the sled is stopped while the torpedo is released to continue out the tube. As the sled and ram has an appreciable mass, a large amount of energy must be absorbed in stopping the sled at the end of the stroke to minimize shock to the structure and to the hull. It is necessary in some installations to absorb the snubbing energy in less than six inches of travel in a reasonably quiet manner.

Old methods of stopping the sled included fastening a tapered plunger onto the front of the sled which entered a fixed socket at the end of the stroke. As the plunger entered the socket at high speed, the water being forced out would build up a pressure in the socket which would slow the sled. The taper would cause the clearance area to become smaller as the velocity became less to keep the pressure reasonably constant throughout the snubbing portion of the stroke. If the launcher were fired accidentally without being flooded there would be no snubbing action and probably both the snubber and ram would be damaged. This made it impossible to test the launcher operation without first submerging it. Also the alignment of the plunger and socket was quite critical.

SUMMARY OF THE INVENTION The high energy short stroke catapult of this invention comprises an elongated cylinder with end-to-end cylindrical compartments and with input ports at opposite ends for communicating, respectively, with a high pressure source of gas or air and a high-pressure source of liquid such as oil. The piston of the ram reciprocates in the cylinder between these ports and through a piston rod is connected to a launching sled. At the beginning of the stroke, high-pressure air is admitted one end port. An exhaust port in the wall of the cylinder intermediate the input ports is covered by a sleeve valve which marks the end of a pressure stroke and the beginning of the deceleration or snubbing action. The sleeve valve separates the oil in one end of the cylinder from the air in the other. As the ram nears the end of its power stroke the sleeve is moved to suddenly release the high-pressure air into a large receiver tank and to permit the application of back pressure to the oil for snubbing.

Other features and objects of this invention will become apparent to those skilled in the art by referring to the preferred embodiment described in detail in the following specification and shown in the accompanying drawing in which:

FIG. 1 has a half-sectional view of the ram and its cylinder of this invention; and

FIG. 2 is a sectional view of a portion of the ram in the stopped position after a power stroke.

The internally machined cylinder receives the piston 12 which drives the piston rod 14. The outer end of the piston rod is connected to a sled part of which is shown at 16 and which carries the torpedo to be launched. O"-rings may be employed for making fluidtight seals between the various moving surfaces of the ram.

In FIG. 1 the power stroke is from right to left and is powered by high-pressured air admitted through conduit 18. Back pressure on the piston is minimized by venting the back space through holes 32 and port 20 to the atmosphere or to receiver tank 22. At the end of the power stroke the high-pressure air is suddenly released through port 20 into receiver 22. The specific mechanism for venting will be discussed below.

Deceleration and return of the piston rod is by means of oil or other liquid at times under considerable pressure in inlet port 24. The end of the acceleration portion of the stroke and the deceleration is marked by the exhaust port 20. Mechanism for releasing the air pressure comprises the free-floating sleeve 30 with O-ring seals bearing against the inner wall of the cylinder as well as the outer surface of the piston rod. The inside diameter of the pneumatic end of the sleeve is preferably relieved as shown at 31 and is perforated at 32 to permit air back of the piston to be exhausted freely through port 20 into.

the receiver tank 22. Further, the inside diameter of the cylinder is stepped to accommodate the reduced thickness of the sleeve. The inside surface 31 of the sleeve is aligned with the surface 31a of the cylinder.

Forward drive floating piston 34 moves freely a limited distance between the shoulders on the piston rod and is normally held in the left-handed position during acceleration by a small orifice 33 through the piston.

When a launching of the sled is to be initiated, all parts of the catapult start from the positions shown in FIG. 1. First, the firing valve 35 is opened, so that some high-pressure air from storage 36 and pump 37 will enter the cylinder. First, leakage will force the floating drive piston 34 against the shoulder 34a on the rod. The entire piston rod and both pistons start to accelerate at the end of the power stroke, both

pistons

12 and 34 enter the relieved portion of sleeve or stop piston 30. The sleeve 30, however, is held firmly against the shoulder 6 by oil pressure sustained by high pressure in the accumulator 7. After piston 34 bottoms inside sleeve, the momentum in the moving mass of the sled and rod compresses the gas between

pistons

12 and 34. Sleeve 30 remain essentially stationary until the gas pressure exceeds the oil pressure on the far side of stop piston 5.

During compression of the gas between

pistons

12 and 34, a portion of this gas exhausts through orifice 33 because of the increase in its pressure above that of the actuating pressure. This exhausting continues at an increased rate as the pressure between

pistons

34 and 12 increases until piston 12 contacts piston 34 at a low relative velocity thereby creating a small pressure pulse in the oil compared to the very large pressure pulse caused if piston 12 had struck sleeve 30 directly.

Meanwhile sleeve 30 is smoothly accelerated forcing oil through a large orifice 24 creating a back pressure proportional to the square of the oil velocity. As the three pistons proceed along the snub cylinder, this orifice back pressure diminishes but the air pressure to the right of piston 41 in the accumulator 40 increases due to compression producing a stopping force on the rod that is reasonably constant. A constant stopping force will snub a moving mass in the shortest distance for a given maximum force level. After the ram is brought to a stop the air pressure in the accumulator tries to return the displaced oil but the check valve 42 closes causing the oil to flow through the small orifice 43. This return oil drives sleeve 30 back to the stop 6, carrying the other pistons, rods and sled at a rather low velocity to prevent damage or noise making jarring to the mechanism. It is important to note that just as deceleration starts, sleeve 30 moves beyond exhaust port 20 and much of the actuating high-pressure gas is dumped suddenly into the receiver tank 22 to abruptly terminate the forward driving air pressure.

After the return of the sleeve 30 to mechanical stop 6, the receiving tank pressure may be applied to the forward side of piston 34. By bleeding off the residual actuating pressure behind piston 12, the whole mechanism can be returned to prefiring position. The system thus described will admit no air bubbles to the water surrounding the ram or launching tube. The bellows operated air valve 47 can be employed to exhaust the cylinder to the atmosphere when the equipment is not submerged. The old method of stopping the sled required that the stopping mechanism be submerged in water to function. If the launcher were actuated in air accidentally or for test purposes, severe damage generally occurred to the equipment with the possibility of injury to anyone standing in front of the launcher. The novel launcher of this invention can be test fired without submergence.

Alternatively, the air side of accumulator 40 may be connected through a check valve to the supply tank ahead of the firing valve. This assures the pressure in the accumulator being at least equal to the actuating pressure.

Also, air side of accumulator 40 may be connected through a small orifice 44 to the supply tank ahead of the firing valve, assuring pressure in the actuator when actuation is possible. This also reduces pressure in the accumulator 7 when low launching speeds are required for low noise level. To lower the pressure in accumulator 40, the quieter is the stopping action but also the greater the travel during stopping. Thus an automatic adjustment of stopping pressure versus launching speed is provided.

A check valve and small orifice not shown, may be used in place of orifice 33. The check valve would allow the actuating gas to fill between

pistons

12 and 34 rapidly while preventing the rapid exhaust of this gas after hitting sleeve 30.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. In combination in a catapult:

an elongated cylinder with two end-to-end compartments,

ports at opposite ends of said cylinder,

one of said end-to-end compartments being larger in diameter than the other,

a piston reciprocable throughout said end-to-end compartments, and a piston rod slidable through one end of said cylinder,

said piston being fitted to the diameter of the smaller compartment,

means to accelerated said piston in one compartment including a relatively high-pressure source of air coupled to the end port in said compartment,

means to decelerate said piston in the other compartment including a liquid-filled shock-absorbing accumulator coupled to the end port in the other compartment,

an exhaust port in the wall of said cylinder near the end of the acceleration portion of the piston stroke and near the beginning of the deceleration portion of the piston stroke,

a free sleeve in said cylinder slidable over said exhaust port to selectively relieve said high-pressure air, and to separate said air and liquid,

said sleeve being fitted to the diameter of the larger com partment,

one end of said sleeve being internally relieved to telescopically receive said piston as the piston moves from the ac- 5 celeration to the deceleration portions of the launching stroke.

2. In combination defined in claim 1, said sleeving being perforated near one end of the relieved portion to freely exhaust air pushed by the accelerating piston to said exhaust port.

3. The combination defined in claim 1 further comprising;

means to cushion the impact of said piston against said sleeve comprising a ring slidably sealed to the piston rod and compartment wall and spaced from the pistons to en trap a quantity of air.

4. In the combination defined in claim 3 said piston having a restricted orifice to push said ring away from said piston.

5. In combination in a high energy catapult for propelling an object, said combination comprising:

an elongated cylinder with ports at opposite ends for communicating, respectively, with a pressure source of gas and a pressure source of liquid,

a piston reciprocable in said cylinder between said ports,

a piston rod connected to said piston,

means for admitting gas at a predetermined pressure to one port for accelerating said piston,

an exhaust port in the wall of said cylinder intermediate said in ut ports,

a v ve sleeve reciprocable in the annular space between said rod and said cylinder and adapted to selectively close said exhaust port near the end of the piston power stroke,

an accumulator, said accumulator having a cylinder divided into two chambers by a slidable piston,

one chamber being filled with liquid and coupled to one end port of the elongated cylinder of said catapult, the other chamber being coupled to a source of air,

a check valve in the liquid conduit between said accumulator and said elongated cylinder to permit rapid exhaust of said liquid, and

a restricted duct connected in parallel with said check valve to slowly return said piston.

6. The combination defined in claim 5 further comprising a receiving tank communicating with said intermediate exhaust port to prevent escape of air bubbles.

45 s w t a s

Claims

1. In combination in a catapult: an elongated cylinder with two end-to-end compartments, ports at opposite ends of said cylinder, one of said end-to-end compartments being larger in diameter than the other, a piston reciprocable throughout said end-to-end compartments, and a piston rod slidable through one end of said cylinder, said piston being fitted to the diameter of the smaller compartment, means to accelerated said piston in one compartment including a relatively high-pressure source of air coupled to the end port in said one compartment, means to decelerate said piston in the other compartment including a liquid-filled shock-absorbing accumulator coupled to the end port in the other compartment, an exhaust port in the wall of said cylinder near the end of the acceleration portion of the piston stroke and near the beginning of the deceleration portion of the piston stroke, a free sleeve in said cylinder slidable over said exhaust port to selectively relieve said high-pressure air, and to separate said air and liquid, said sleeve being fitted to the diameter of the larger compartment, one end Of said sleeve being internally relieved to telescopically receive said piston as the piston moves from the acceleration to the deceleration portions of the launching stroke.

3. The combination defined in claim 1 further comprising; means to cushion the impact of said piston against said sleeve comprising a ring slidably sealed to the piston rod and compartment wall and spaced from the pistons to entrap a quantity of air.

5. In combination in a high energy catapult for propelling an object, said combination comprising: an elongated cylinder with ports at opposite ends for communicating, respectively, with a pressure source of gas and a pressure source of liquid, a piston reciprocable in said cylinder between said ports, a piston rod connected to said piston, means for admitting gas at a predetermined pressure to one port for accelerating said piston, an exhaust port in the wall of said cylinder intermediate said input ports, a valve sleeve reciprocable in the annular space between said rod and said cylinder and adapted to selectively close said exhaust port near the end of the piston power stroke, an accumulator, said accumulator having a cylinder divided into two chambers by a slidable piston, one chamber being filled with liquid and coupled to one end port of the elongated cylinder of said catapult, the other chamber being coupled to a source of air, a check valve in the liquid conduit between said accumulator and said elongated cylinder to permit rapid exhaust of said liquid, and a restricted duct connected in parallel with said check valve to slowly return said piston.