GB2481864A

GB2481864A - Valve to reduce recoil in a hand held percussive tool

Info

Publication number: GB2481864A
Application number: GB1011671.3A
Authority: GB
Inventors: Alexander Ross
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-07-10
Filing date: 2010-07-10
Publication date: 2012-01-11
Also published as: GB201011671D0

Abstract

A hammer piston for a percussive tool wherein the piston comprises air passages containing one-way valves such that the piston returns to its starting position at a slower speed than it moves during its working stroke, thereby reducing recoil. There may also be a washer or trap comprising holes, slits or slots to vent air during the return phase of the hammer block and to close the valves in the piston during the first phase where impact force is delivered. There may also be a counterweight with hinged arms. The percussive tool may be a pneumatic chisel or hammer, stapler, air drill or a pneumatic gun and the hammer piston would allow it to be used horizontally or in an inverted or upside down overhead position.

Description

Recoilless Valve Block

Background of the invention

This invention (pneumatic recoilless valve block hereinafter called the "valve block") arose from a tender to remove a large amount of rendering to a boundary wall as a result of vandalism. It is not possible to use a pneumatic chisel without my invention because they can only be used in a vertical direction downwards into the ground.

My invention makes it possible to use a pneumatic chisel at any angle and even one handed.

Problem this Patent Solves The recoil from the blow a pneumatic chisel makes is equal to forces it impacts with.

This makes pneumatic chisels difficult to handle as you need two hands to hold it down and is most suitable for physically fit operators.

My invention removes or drastically reduces the recoil force in the pneumatic chisel.

This means pneumatic chisels can now be designed much the same way as electric or air drills are. They can be used one handed and horizontally or at any angle to the ground.

This makes them easier and safer to operate.

My one way valve block is more efficient than having a hinged valve. A hinged valve could break and damage the cylinder. A hinged valve would not work well in a horizontal position and certainly not an overhead position.

What this invention does.

The pneumatic chisel currently uses a "hammer block" to travel inside a cylinder inside the pneumatic chisel and deliver an impact force on the top of the chisel. There are one or more * 25 air inlets in the valve block that open and close to allow the block go back and forth along the cylinder but dissipating the force on the return stroke.

When the chisel is in contact with the ground this force is then directed into the ground.

I have invented a replacement for the hammer block which is also a one way valve block.

My valve allows air pressure to drive the one way valve block onto the chisel head as before.

It delivers exactly the same impact force as before.

However for the return stroke the air pressure being directed to the opposite face of the block opens the one way valve allowing air to vent or escape and reducing the force, The valve bock is allowed to retain just enough force to travel back up the cylinder ready for the next impact sequence.

Key Features of the Invention There is a hammer block with two (or more holes).

Attached to the hammer block is a short spindle that allows a washer to travel up and down.

The washer has a square hole to match the cross section of the spindle and holes that are offset from the valve block so that there is no overlap between the holes.

Finally the spindle has a stop to arrest the travel of the washer.

Depending upon the manufacturing process the spindle could be part of the valve block or fixed into it (by a screw thread for example).

When the valve block is projected downwards onto the chisel head in the impact sequence or stroke it forces the washer down onto the face of the valve block; and seals the holes in the valve block. The one way valve is thus shut during this phase.

When the valve block has impacted the chisel the air supply switches from behind the valve block to in front of it as with current designs.

This starts the second phase or sequence where the valve block is driven back up the cylinder to its starting position again. During this phase the holes in the valve block allow the one way valve to open. The washer then travels up the spindle allowing air to vent into the cylinder and escape. The holes are designed just to have a wide enough diameter for the valve block to have enough air and pneumatic force to travel back to its starting position and no more.

The weight of the washer and the holes in the washer also need designing for optimum efficiency to get the valve block ready for the impact phase to begin again as before.

s Other Features of the Invention The pneumatic drill can now be designed to work by holding it with one hand which I would refer to as a pistol version. However a heavy version using two hands could be used as a rifle which may be more useful for mining.

There are some pneumatic staple guns manufactured that suffer the same disadvantages as the present pneumatic chisels.Using this valve block heavy staples can be used and driven to a deeper depth of fixture.

The use of the valve block designed here is not limited to a chisel or stapler. It can be used in any tool or gun that requires a two phase pneumatic operation.

Although the valve block does return up the cylinder in conducts no recoil and is therefore called "recoilless" here as it has greatly reduced recoil so that no recoil is felt by the user. The recoilless effect is similar to a heavy firearm such as an antitank gun, whose chemically induced recoil is reduced by venting the blast to the rear.

Brief Introduction to Patent Drawings

The drawings are shown schematic and not to scale as the dimensions of the pneumatic mechanism or tool enclosing the valve block may vary.

The spindle that guides the washer needs to have a square (or some other appropriate) shaped cross section. This is to allow the washer holes to be offset 90 degrees to the holes in the valve block. I do not expect the washer to need the cross section of the spindle to be threaded forcing the washer to rotate. However, this would improve braking performance in a pneumatic rapid passenger transit system (the washer could be replaced by a hinged blind to close the holes in the hammer block component).

I have shown two holes for the valve block and the washer. However, the number and diameter or size and shape of the holes can vary. The holes or air passages permit the supply of air through the valve block only on the return stroke.

The reduction in the distance the valve block travels on the return stroke can be controlled by ao setting the design measurements and limits for the washer's size and weight, the size and weight of the holes for the valve block, and the distance the washer travels up the spindle.

I anticipate that the distance the washer travels up the spindle should be small relative to the valve block.

The valve block is intended to be incorporated into existing pneumatic equipment and machinery to replace and improve upon the hammer block that is presently used.

Details of Drawings Two drawings are included showing how the existing or old mechanism used in pneumatic chisels uses a hammer block to drive a chisel in a two stroke action.

One drawing is included drawing showing how the new recoilless valve block is constructed and its principal parts.

Two drawings are included showing the new valve block replacing the old hammer block and its operational effect. The washer slides down the spindle to cover the holes in the valve block during the impact phase. So the holes in the valve block and washer are designed so that they do not overlap. The valve block simply needs to fit inside the cylinder to keep an air g tight sea so their cross sectional shapes must match.

I have included a drawing showing how the valve block can be used in a hydraulic system to close a rogue oil well. The washer or trap can have one or more closure plates or wings although I have shown two schematically. The wings rotate around the spindle. They can be designed for a suitable width and inclination to take a fixed time to deploy down the pipe.

The wings may even be hinged or sprung to facilitate closure against the face of the valve block. The face of the hammer block may also have recesses built into it to accept the wings upon the valves closure. Since there may be a large pressure in the oil pipe total closure may not be necessary for the first valve block. By deploying subsequent valve blocks the well pipe can be shut off gradually and filled with cement ecetera. There may be more than two arms for the counterweight. It can be fixed to the hammer block. Both the hammer block and counterweight have no thread but a smooth hole so that they are free to move along the extended spindle. The only component moving the valve along the spindle is the washer or trap that rotates and moves along the thread until the stop at the counterweight end stops it going any farther.

Examples Uses of the Recoilless Valve Block The invention allows all the present day uses of the pneumatic chisel but now can be used in many more tasks. For example it can be used under water in a marine environment as it is not electrically operated. One marine use is to strip barnacles from the underside of ships without the ships going into dry dock. A pneumatic chisel with this invention can now be held and operated horizontally so it can be used to remove plaster or rendering on walls.

It would also be a great improvement to mining safety and efficiency using pneumatic chisels.

Rather than having a chisel the pistol, or rifle, could be modified to fire staples or bullets by incorporating a magazine feed.

Although its use in a pneumatic gun may allow for automatic loading of the magazine by using the waste air expelled by the valve block it will not remove other disadvantages of using pneumatic guns as weapons and is probably more suitable for non military purposes such as staplers.

The valve block could be incorporated into pneumatic scribes, miniature chisels for fossil work While air drills are currently manufactured the valve block now allows a hammer action air drill to be developed.

Pneumatic post or pneumatic mail systems deliver letters (or medical samples) through pressurized air tubes between different departments. This invention may make them safer to transport more breakable or hazardous materials as they can now be slowed down as they approach their destination.

A rapid transport system could be developed using the same system but enlarged by incorporating this valve block to provide a breaking mechanism or aid.

The valve block design could also be used as a hydraulic valve instead of a pneumatic valve.

As a hydraulic valve it could be used to close and seal oil pipe lines as the British Petroleum spillage off the coast of the eastern USA which at the date of this application is uncontrollable.

Claims

Patent Claims Definition of the invention The Recoilless Valve Block is a control device to allow air to operate effectively in one direction only for pneumatic or hydraulic systems. It can be used in order to create an impact force and eliminate the pneumatic recoil force experienced by the operator of the appliance or device it is incorporated into. It can be used in either pneumatic or hydraulic systems too.The Pneumatic Recoilless Valve Block is a new type of pneumatic actuator that converts energy in the form of compressed air into the motion of the valve block itself and then it can be changed back to energy if the valve block is used as an impact device (such as in a chisel but not in a transportation system).Existing hammer blocks inside pneumatic chisels do not operate as one way valves but slide is back and forth inside a cylinder or container.The valve block can be used as an integral component in or part of pneumatic chisels, staplers, machines, or systems. It could form part of a passenger carriage or transport system to slow down or brake a vessel as it arrives at its destination.The valve block is not solid but contains airways to allow the passage of air in the second or return phase.The valve block contains a valve mechanism that is self correcting and self setting.The valve block adjusts itself depending upon the direction of the air supply that it receives, reaches it to control the force generated by that air.The valve block does not use an internal flap as a one way water valve does. Using a flap such as the cap on top of a steam pipe would depend upon gravity or a spring to close it.Therefore the new valve block eliminates the liability of mechanical fatigue and failure.The design allows pneumatic tools to be used in any direction, even vertically upwards.The valve block eliminates the recoil presently limiting the operability and safety of pneumatic tools and devices. The valve block is also a novel way of closing gas and liquid pipes and valves.Similar inventions I am not aware of any similar inventions to this pneumatic valve design but there are some pneumatic devices that can be improved with my invention.1. The spring return pneumatic piston which is not generally incorporated into pneumatic chisels because of the risk of material failure inside the cylinder. For the same reason this invention does not incorporate a flap.
2. Holman Projector worked on the principle of a pneumatic mortar, using compressed air or high pressure steam to fire an explosive projectile at enemy aircraft during World War II.
3. Transportation passenger systems have never used compressed air although it is very efficient. A similar system was used to send money and messages in tubes. Pneumatic post or pneumatic mail is a system to deliver letters through pressurized air tubes. It was invented by the Scottish engineer William Murdoch in the 1 800s. There is no need to brake or slow down the capsule at the end of its journey. However a passenger system would need to brake the capsule or carriage at its arrival point. My valve bock design could be used to bleed of the air behind the carriage so it reduces the force propelling it forwards.
4. Pneumatic guns have a mechanism for the rounds to be automatically reloaded, that must also be powered by the air presure. Many modern Gunpowder firearms re-use the energy from the propellant to accomplish this. With my design the air that is allowed to escape or vented on the return stroke could be redirected to reload the weapon.