US3431725A - High energy rate actuator - Google Patents

Description

March 1l, 1969 HSIN SHENG CHEN HIGH ENERGY RATE ACTUATOR Filed Feb, 1, 1967 United States Patent O 3,431,725 HIGH ENERGY RATE ACTUATOR Hsin Sheng Chen, Somerset, NJ., assignor to Ingersoll- Rand Company, New York, N.Y., a corporation of New Jersey Filed Feb. 1, 1967, Ser. No. 613,259 U.S. Cl. 60-1 13 Claims Int. Cl. F1511 13/04, 15/17 ABSTRACT OF THE DISCLOSURE A high energy -rate actuator which moves a ram at high speed to deliver an impact to a workpiece. A chamber lled with liquid is pressurized and a seal is formed between a triggering piston and the ram. The seal is broken and the liquid under pressure acts on the ram to impel it forward at high speed. The device may be preloaded to a varying degree by means of a hydraulic loading spring to Vary the speed and impacting energy of the ram.

This invention relates to a high energy rate actuator and more particularly to a high energy rate actuator employing the compressibility of liquid as the energy transfer medium to provide a force to drive a ra-m or the like to deliver an impact to a workpiece or to accomplish other fast operations. The invention may be used in most places where it is desired to deliver an impact to a workpiece such as in -rock drills, forging presses and the like or where it is desired to perform a fast operation such as quickly closing a valve.

In most prior devices of this type it has been necessary to have liquid or gas flow in or out of a chamber through a valve or orice during the power cycle. This -ow through an orice limits the speed of the ram. This tlow through an orice therefore limits the eticiency of the device. Other devices such as gun powder actuated tools have the disadvantage that when varying operations are to be done, trial and error must -be used to determine the correct power level. In current impacting devices such as air powered tools and gun powder actuators, thereis no intermediate range of impacting speeds. Air actuated tools operate a-t too low a speed for certain operations and gun powder actuators operate at too high a speed for certain operations. Air and gun powder actuated impact tools can be dangerous due to their high energy content per unit initial volume. Air actuated power tools have the additional disadvantage that air o-r other gas cannot deliver as great an amount of energy per volume of displacement during expansion as liquid. This is due to the relative incompressibility of liquid. This necessitates a longer stroke and a larger -ram when using air. Since the ram mus-t be larger, higher speed is not obtainable.

It is therefore the principal object of this invention to provide a high energy rate actuator which does not require the ow of fluid through an orifice during the power cycle and therefore operates at higher speed and provides greater efficiency.

It is ya further object of this invention to provide an impactor which is capable of operating at intermediate speed.

It is another object of this invention to provide a high energy Irate actuator which is safer than prior devices.

In general, these objects are carried out by providing a casing defining a chamber which is filled with liquid and triggering means disposed within the chamber. A ram is mounted for reciprocal movement in the chamber and extending out of the casing. There is means for forming Ia seal between the triggering means and the ram. There is provided means for applying pressure to the liquid 3,431,725 Patented Mar. 11, 1969 ice in the chamber and means for breaking the seal to allow the liquid under pressure to impel the ram away from the triggering means. The chamber is substantially closed after the seal is broken.

The `foregoing and other objects will become apparent from the following description -and drawings wherein:

FIG. 1 is a schematic diagram of the actuator of this invention;

FIG. 2 is a sectional elevation showing one embodiment of this invention; and

FIG. 3 is a view similar to FIG. 2 with the ram of the actuator in a position just prior to actuation; the ram is shown in dotted lines after actuation.

Referring to the drawings and in particular to FIG. 2, there is shown an actuator generally indicated at 1. This actuator has a casing 2 with a wall S to divide the casing into first and second chambers 6 and 7 respectively. The first chamber 6 has a ram 10 movably mounted therein and extending out of the end wall 46 of the casing 2 through a passage 44.

The ram 10 is provided with an enlarged portion 12 and `a work contacting end 11. The opposite end of the ram is provided with an enlarged portion 14. Since the chamber 6 is larger than the end 14 of the ram 10, the bore 44 in the end wall 46 is the sole guide for the ram 10.

The wall 8 has a passage 36 therethrough which is counterbored at 37. Triggering means is mounted within this passage and includes a spring piston 34 mounted within the bore 36 and extending into the second chamber 7. This piston 34 is provided with an enlarged portion 35 to prevent it from being forced through the bore 36.

A triggering piston 21 forms part of the triggering means and is mounted within the counterbored portion 37 of the passage 36 and is adapted to move independently of the piston 34. The triggering piston 21 has a limited flow valve therein which includes a bore 22, ball 23 and bore 24. The bore 22 includes passages (not shown) which permit liquid to pass from inside the seal 20l to the passage 24 even when the ball 23 is seated. The passage 24 leads to a portion of the bore 36 and to a passage 26 in the wall 8.

Each of the chambers 6 and 7 are lilled with a liquid such as a silicone uid. The liquid in the second chamber 7 is placed under pressure by means of a loading piston 33 which is engaged by a loading sorew 30, 31 which is threadedly attached to casing cover 52 at 32. As the loading screw 30, 31 is rotated, the loading piston is moved in or out to apply more or less pressure on the liquid in the second chamber 7 and as a result on the spring piston 34.

The first chamber is filled with a liquid which is preferably, but not necessarily, the same liquid as that in chamber 7. This liquid is supplied from a reservoir 3, through a delivery pump 32, conduit 40, to a passage 41, in the wall 8 and into the chamber 6.

Operation To set the actuator for a particular impact energy and speed, the actuator is preloaded by tightening the loading screw 30 to force piston 33 inwardly to apply a preset pressure to the liquid in the second chamber 7. This fonce biases the spring piston 34 towards the rst chamber 6.

From the position of FIG. 2, the ram 10 is moved toward the triggering means so that the O-ring 20, secured in the llower portion of the triggering piston 21 provides a seal between the triggering means and the ram. This movement may be accomplished by any suitable means. The iirst chamber 6 is then pressurized by pumping liquid through conduits 40 and 41 into the chamber 6.

The fluid under pressure acts on surface 17 of the enlarged portion 14 and the triggering piston 21 to move the ram and triggering piston toward the spring piston 34. Any liquid trapped inside the O-ring seal ows through the limited ow valve, through line 4, and back to the reservoir 3. The seal 20 prevents additional liquid from flowing through the valve 23.

Additional pressure is applied to the chamber 6 to move the ram and triggering piston 21 toward the piston 34. The triggering piston 21 will first contact the spring piston 34. Additional pressure is applied to overcome the force developed 'by the liquid in the second chamber or loading spring 7. When this force is overcome, the ram 10, triggering piston 21, and spring piston 34 will move until the enlarged portion 12 of the ram 10 engages a stop 13, as shown in FIG. 3. At this point, the triggering piston 21 and spring piston 34 will continue to move upward on the application of additional pressure but the ram will remain stationary. In order to move upward after movement of the ram has stopped, the trigger piston 21 must be dimensioned so that the surface area on its underside which is exposed to the pressure in chamber 6 exceeds the area of surface 39. Thus if, in the embodiment shown, d1 represents the largest diameter of the trigger piston 21, d2 the reduced portion, d3 the diameter within the counterbore 37 and d4 the area within the O-ring 20, then (d1-d4)}(d3d2) is greater than al1-d2. The seal between the triggering `means and the enlarged portion 14 will then be broken and the pressure in cham-ber 6 will act on the end surface 16 of the ram 10.

Since the end surface 16 is larger in area than the surface area 17, the pressure in the chamber 6 will exert a greater force on this end tending to move the ram 10 downward as viewed in the drawing at great speed and high force, It may be desirable to continue to operate the pump 32 |while the ram is moving forward to deliver an impact. The feature which makes this invention operate at speeds not previously obtainable is the fact that the chamber 6 is substantially closed after the seal is broken. Fluid does not have to flow through any orifice so the speed of movement is not limited by the speed at which fluid flows through an orifice. The end of the ram may contact a workpiece (not shown) to deliver an impact to the workprece.

In order to prevent the ram from striking the end 46 of the casing 1, there is provided a cushioning device. This cushion consists of a cylinderdivider 51 which is placed near the end of the chamber 6. The divider provides an opening which is substantially the same size as the enlarged portion 14 of the ram 10. As the ram 10 moves forward, a seal is developed between the divider 51 and the ram portion 14. This seal creates a cushion chamber 50. As the ram continues to move forward, the liquid in the newly formed chamber is compressed to form a liquid spring and prevent the end 14 from engaging the cylinder lcwall 46. This position is shown in outline form in An annular groove 42 is provided in the end wall 46 around the bore 44 to collect uid which leaks between the ram 10 and the passage 44. As the ram moves forward to deliver an impact to the workpiece, uid is collected in the groove 42 where it drains into conduits 43 and 5 and back into the reservoir 3.

From the foregoing it can be seen that a novel high energy rate actuator has been provided. The present device is particularly useful for obtaining impacting speeds in a range between pneumatic actuators and gunpowder actuators. I have found that the impactor of this invention Works best in the speed range of 100 ft./sec. to 800 ft./sec. although it is not intended that these speeds be a limiting feature of this invention. If desired, a device according to this invention may be designed to give speeds higher than gunpowder actuators or lower than gas tools.

The impacting speed may be varied by varying the pressure in the second or 'biasing chamber 7. If the pressure in chamber 7 is increased, the pressure in chamber 6 necessary to set the device off must be greater and, therefore, a greater impact energy force and speed are developed. Since the chamber 6 is larger in cross-sectional area than the cross-sectional area of the enlarged portion 14 of the ram 10, the tendency of the ram to be slowed by the ram engaging the side walls of the casing is eliminated.

For ease of manufacture, I have made the triggering means in two parts, the triggering piston 21 and the spring piston 34. In some instances, however, it may be desirable to make the pistons 34 and 21 a single unit. If the triggering piston 21 and spring piston 34 are made as shown in the drawings, the space between these members becomes important. In order for the device to deliver an impact, the distance between the spring piston 34 and the triggering piston 21 must be less than the distance Ibetween the enlarged portion 12 of the fram 10 and the stop 13. When the seal 20 is iirst formed, the latter distance must be less than the -distance between the surface 39 and the wall 8. This latter difference insures that the seal 20 will be broken to start the ram on its impacting stroke.

In the embodiment shown, the ram 10 is moved toward the second chamber 7 along with the triggering piston 21 for a short distance when the chamber is pressurized before the seal between the triggering means and the ram is broken. In certain applications it may be desirable to break the seal by some other means.

Since this invention uses hydraulic fluids as an energy transfer medium, it is inherently safer than a similar device using compressed air or gunpowder. Even ignoring the safety considerations, in order to achieve the same speed and force using compressed air, a much larger stroke must be used. If the casing failed while using compressed air, an explosion may be caused, while if causing failure occurred in the present invention using hydraulic fluid, the only problem would be leakage as pressure would drop quickly and the uid would merely leak out of the casing.

From the foregoing description it can be seen that the objects of this invention have been carried out. It is intended that the foregoing description be merely that of a preferred embodiment and that the invention be limited only by that which is within the scope of the appended claims.

I claim:

1. A high energy rate actuator comprising:

a casing defining a chamber filled with fluid;

triggering means disposed within said chamber;

a ram mounted for reciprocal movement within said chamber and extending out of said casing;

means forming a seal between said ram and triggering means; and

means for applying -pressure to the fluid in said chamber for breaking said seal and impelling said ram away from said triggering means;

said chamber being substantially closed after said seal is broken.

2. The actuator of claim 1 wherein said casing includes a wall having a passage therethrough and said triggering means is moveably mounted in said passage and said seal is broken by moving said triggering means away from said ram.

3. The actuator of claim 2 wherein the fluid under pressure is a liquid and acts on said triggering means to move said triggering means away from said ram to break said seal and further including means for applying a load on said triggering means for increasing the force necessary to break said seal.

4. The actuator of claim 3 wherein said loading means includes a second chamber filled with hydraulic uid, means for pressurizing said hydraulic fluid, and means for transferring said pressure to said triggering means.

5. The actuator of claim 4 wherein said pressurizing means is an adjustable piston.

6. The actuator of claim 2 wherein said means for applying pressure to said fluid is a pump.

7. The actuator of claim 6 wherein said first chamber has a cross-sectional area larger than the cross-sectional area of said ram.

8. The actuator of claim 7 further including means for preventing said ram from contacting the end of said casing opposite to said triggering means.

9. A high energy rate actuator comprising:

a casing;

a wall having a passage therethrough dividing said casing into rst and second chambers; n

triggering means mounted in said passage and extending into said first chamber;

said rst chamber being filled with liquid;

a ram moveably mounted in and extending out of said rst chamber;

seal means interposed between said ram and said triggering means; and

means for pressurizing said iirst chamber to move said triggering means toward said second chamber to break said seal and impel said ram in a direction away from said triggering means.

10. The actuator of claim 9 wherein said second chamber is lled with liquid and means are provided for preloading said second chamber for increasing the force required to break said seal.

11. The actuator of claim 10 wherein said pressurizing means is a pump and said preloading means is an adjustable piston.

12. The actuator of claim 11 further including means for preventing said ram from hitting the end Wall of Said casing.

13. The actuator of claim 12 wherein the cross-sectional area of said rst chamber is larger than the cross-sectional area of said ram.

References Cited UNITED STATES PATENTS 2,648,949 8/1953 Taylor 60-1 EDGAR W. GEOGHEGAN, Primary Examiner.

U.S. Cl. X.R. 60-52; 92-85

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