GB2076048A

GB2076048A - Impact-delivering tool

Info

Publication number: GB2076048A
Application number: GB8015844A
Authority: GB
Original assignee: JAYNE ENGINEERING Inc
Current assignee: JAYNE ENGINEERING Inc
Priority date: 1980-05-13
Filing date: 1980-05-13
Publication date: 1981-11-25

Abstract

In the illustrated state of the tool, e.g. for driving nails, driver 12 is held about four-fifths of the distance towards its foremost position by sear 74. Fuel nozzle 30 and ports 28 are closed, as also is precompression chamber 44. Upon actuation of trigger 80, driver 12 is moved rearwardly by spring 55. As it moves, piston 38 uncovers supply port 30 and nozzle 31 sprays fuel into the precompression chamber 44 which also draws in air by way of port 24. Fuel/gas mixture already in the combustion chamber 46 is compressed and when piston 38 encounters crystal assembly 64 the latter initiates a spark at plug 56 to drive driver 12 to the left to impact a workpiece (such as a nail, not shown) and bring the ports back to the position shown, with fresh fuel/air mixture transferred from chamber 44 through ports 52, 50, 54 into the combustion chamber 46. <IMAGE>

Description

SPECIFICATION Impact-delivering tool This invention concerns an impact-delivering tool.

As hitherto proposed, such tools have generally been either cartridge-actuated (e.g. where hard metal pins or bolts require to be driven into structural materials such as brick, concrete or steel) or compressed-air operated (e.g. wherein successive nail-driving operations are required to be performed in industrial production.

An object of the present invention is to provide an impact-delivering tool which is simple in construction, inexpensive to manufacture, and reliable and versatile in its operation, having a self contained fuel supply so that it can be used for effecting impacting operations, such as driving of nails, in locations where no external power source is available and without involving the use of cartridges which have attendant danger for personnel using the tool.

With this object in view, the present invention provides an impact-delivering tool of the internal combustion type and having a self-contained fuel supply, comprising a body communicating with the fuel supply and with atmosphere, a driver within the body and dividing it into a compression chamber and a combustion chamber, the driver including a piston having integral valving, fuel metering means integral with the body and driver, ignition means for igniting the fuel air mixture for moving the driver, and trigger means for actuating the driver.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a side elevational view of a preferred embodiment of the impact-delivering tool of the invention; Fig. 2 is a sectional elevation of the impact delivering tool of Fig. 1 , with certain parts omitted for clarity; Fig. 3 is a side elevational view of a cocking handle for manually cocking the impact device; Fig. 4 is an end elevational view of the cocking handle of Fig. 3; Fig. 5 is a fragmentary cross-sectional view of a modified form of ignition means which can be incorporated in the tool of Figs. 1 and 2; and Figs. 6, 7, 8 and 9 are schematic sectional side views illustrating successive positions of certain of the parts of the tool of Figs. 1 and 2, during the operation thereof.

- The illustrated embodiment of the impact delivering tool of the invention comprises, primarily, four components, namely: a main body .10, a driver 12, ignition means 14, and a trigger assembly 1 5.

Herefollowing, for simplification of this description, the terms "front" and "forward" will refer to the left as viewed in Figs. 1 and 2 of the drawing, while the words "rear" and "rearward" will refer to the right as viewed in those figures.

The main body 10 includes a longitudinallyextending large-bore cylinder 1 6 having an integral axially-aligned small-bore cylinder 18, of lesser diameter than that of large-bore cylinder 16, extending rearwardly therefrom.

An integral pistol-grip type handle 20 depends therefrom approximately at the transition between the cylinders 1 6 and 18, adjacent the rear end of the tool.

The large-bore cylinder 1 6 is partially closed at its front end by an end cap 22 threaded thereon.

An inlet port 24, controlled by a one-way readtype or flap-type check valve 26, is provided adjacent the forward end of the large-bore cylinder 16, in the upper wall thereof, and disposed approximately centrally along the length of the cylinder 16 are exhaust ports 28. The purposes of the inlet port 24, the check valve 26 and the exhaust ports 28 will be described in detail, shortly.

A fuel supply port 30 is provided adjacent the forward end of the large-bore cylinder 1 6 in the lower wall thereof, this port 30 having a spray nozzle 31 threadedly engaged therein and being coupled to an aerosol butane bottle 32 or other fuel supply, there being a regulating or cut-off valve 33 disposed between the bottle 32 and the nozzle 31.

A second or forward handle 34 extends transversely outwardly from the exterior of the main body 10 adjacent the forward end of the tool, and a muffler or silencer 35 mounted on the main body 10 is connected to the exhaust ports 28 by lines 36.

The driver 12 includes a hollow piston 38 tightly sleeved by the large-bore cylinder 16, the piston 38 being open at its forward end and closed at its rearward end by an end wall 40, the end wall 40 having a centrally-disposed integral hollow piston shaft 42 extending rearwardly therefrom.

The piston shaft 42 is of appropriate diameter to be tightly sleeved by the small-bore cylinder 1 8 in rearward positions of the piston shaft 42.

The end cap 22, the hollow piston 38, the end wall 40 and the hollow piston shaft 42 of the driver 12 effectively divide the large-bore cylinder 1 6 into a precompression chamber 44 disposed forwardly of the end wall 40 and a combustion chamber 46 disposed rearwardly thereof, all for purposes in which will be explained shortly.

An impact rod 48 is disposed on the longitudinal central axis of the tool and has a forward portion extending outwardly from the large-bore cylinder 1 6 through the end cap 22 and a rearward portion threadedly engaged in the end wall 40 of the hollow piston 38 and coaxially aligned with the hollow piston shaft 42.

A central recess 50 extends longitudinally into the rear end of the impact rod 48 and opens into the hollow interior of the piston shaft 42, while a first or forward transversely-extending port 52 in the rear end of the impact rod 48 opens into the central recess 50 thereby providing for communication between the precompression chamber 44 and the bore of piston shaft 42.

A second or rear transversely-extending port 54 adjacent the rear end of the hollow piston shaft 42 provides communication between the bore of the piston shaft 42 and the combustion chamber 46.

A compression spring 55 is sleeved by the hollow piston 38 and is captive within the precompression chamber 44, abutting the end cap 22 at its forward end and abutting the piston end wall 40 at its rear end, the spring serving to urge the driver 1 2 in a rearward direction.

The ignition means 14 includes a spark plug 56 disposed in a rear wall of the large-bore cylinder 1 6 and projecting into the combustion chamber 46.

In a preferred form of the invention, as shown in Figs. 1 and 2, a wire 58 connects the spark plug 56 to a piezoelectric crystal 60 provided in a housing 62 disposed at the rear end of the smallbore cylinder 18, the crystal 60 serving to convert the mechanical energy of a sudden pressure exerted on it into a discharge of electricity as will be referred to later.

The crystal 60 is mounted within the housing 62 in a crystal assembly 64 having a contact member 66 in the form of a protrusion extending downwardly from the housing 62 through an opening 68 provided in the upper wall of the small-bore cylinder 1 8 into interior of said cylinder 1 8.

The position of the contact member 66 within the small-bore cylinder 1 8 is adjustable, with the crystal assembly 64 and the crystal 60 being slidable longitudinally relative to the housing 62 over the distance indicated at X and adapted to be locked in a selected position by a thumb screw 70.

The contact member 66 extends into the interior of the small-bore cylinder 18 by a sufficient distance to be contacted by a bevelled surfaces 72 on the rear end of the hollow piston shaft 42 of the driver 12, as the driver 12 moves rearwardly.

The distance traversed by the driver 12 before a spark is triggered at the spark plug 56, (and therefore the compression ratio) is determined by adjusting the position of the crystal assembly 64 relative to the housings 62.

In the modified form shown in Fig. 5, the spark plug 56 is connected to a microswitch 60' provided in a housing 62' disposed at the rear end of the small-bore cylinder 1 8, with an induction coil 64' and a power source, such as a battery 65', being disposed between the spark plug 56 and the microswitch 60', as shown.

The microswitch 60' has an actuating or contact member 66', in the form of a wheel, extending downwardly from the housing 62' through an opening 68' provided in the upper wall of the small-bore cylinder 1 8 into the interior of the small-bore cylinder 1 8.

The position of the actuating or contact member 66' within the small-bore cylinder 1 8 is adjustable, with the microswitch 60' being slidabie longitudinally relative to housing 62' and adapted to be locked in preset position, such as by the thumb screw 70'.

The actuating member 66' extends into the interior of the small-bore cylinder 1 8 a sufficient distance to be contacted by a bevelled surface 72 on the rear end of the hollow piston shaft 42 of the driver 12 as the driver 12 moves rearwardly.

The distance traversed by the driver 12 before a spark is triggered at the spark plug 56, (and therefore the compression ratio) is determined by adjusting the position of the microswitch 60 relative to the housing 62'.

The trigger assembly 1 5 includes a vertically- extending sear 74 slidably disposed in a cavity 76 in the handle 20, the sear 74 being releasably supported in a raised position wherein its upper end is positioned in the interior of the small-bore cylinder 1 8 and in contact with the rear face of the hollow piston shaft 42 by a leaf spring 78 extending between the bottom edge of the sear 74 and the bottom wall of the cavity 76.

When the device is idle, the driver 12 is precluded from moving to the rear of the cylinder 18, due to contact of the sear 74 with the rear face of piston shaft 42.

A finger-engageable trigger 80 is mounted for horizontal sliding movement relative to the handle cavity 76 and is spring loaded by a leaf spring 82 extending between a rear edge of the trigger 80 and a wall of the cavity 76.

A flat spring 84 extends rearwardly from the trigger 80 and has a free end which is engageable in a notch 86 and the sear 74.

When the trigger 80, normally held in a forward position by the spring 82, is depressed, the spring 84, which is secured to the trigger 80 at one end and lodged in notch 86 of the sear 74 at the other end begins to force the sear 74 to move in a downward direction. When a bevelled corner 88 of the sear 74 passes below the rear edge of the piston shaft 42 and into contact with a bevelled surface 72 thereof, the driver 12, under the great force of the compression spring 55, begins to slide rearwardly, forcing the sear 74 downwardly into the handle cavity 76so that. the upper end of the sear 74 is no longer positioned in the interior of the small-bore cylinder 18, whereby the driver 12 is permitted to move rearwardly into contact with the contact member 66 or 66' of the ignition means 14. As the sear 74 is forced downwardly by rearward movement of the driver 12, the downward movement of the notch 86, relative to the spring 84, allows the spring 84 to snap out of the notch 86. This frees the sear 74 to move upwardly and catch the driver 12 as soon as the latter moves forwardly.

The trigger mechanism 1 5 is reset by releasing the trigger 80 which permits the spring 84 to snap back into the notch 86 of the sear 74, the sear e74 being urged upwardly into the small-bore cylinder 18 by the spring 78 once the driver 12 returns to a forward position.

It will be recalled that the cylinder 1 6 is divided into the precompression chamber 44 and the combustion chamber 46.

The inlet port 24 and-the check valve 26 permit the passage of air into the precompression chamber 44. The combustion chamber 46 is open to the exhaust ports 28 in the large-bore cylinder 16 only when the piston 38 of the driver 12 has moved to a forward-most position. The port 54 in the hollow piston shaft 42 is sealed by the wall of the small bore cylinder 1 8 except when the driver 12 has moved to a forward-most position, at which time the rear port 54 is opened to the combustion chamber 46, thereby permitting passage of air from the precompression chamber 44 to the combustion chamber 46.

In an idle or loaded state, as shown in Figs. 2 and 5, the driver 1 2 is held approximately four fifths of the distance toward its forwardmost position by sear 74. The fuel-supply nozzle 30 and the exhaust ports 28 are closed off by the wall of the hollow piston 38, and the precompression chamber 44 is closed off from the combustion chamber 46.

The combustion chamber 46 contains a fuel-air mixture. When the trigger 80 is depressed, the driver 12 begins to move rearwardly under the force of the spring 55. As shown in Fig. 6, as the piston 38 moves rearwardly it uncovers the fuel supply port 30, whereupon the spray-nozzle 31 sprays fuel into the precompression chamber 44 in an amount proportional to the period of time that the port 30 remains uncovered. The increasing volume of the precompression chamber 44 draws in exterior air through the inlet port 24. Simultaneously the decreasing volume of the combustion chamber 46 compresses the gases confined therein.When the end of the piston shaft 42 impacts the contact member 66 or 66' of the ignition means 14 at the pre-set position, the spark plug 56 is energised thereby causing the gases in the, combustion chamber 46 to burn rapidly, thereby reversing the direction of movement of the driver 1 2 to the power stroke as shown in Fig. 7.

As the hollow piston 38 of the driver 12 moves forwardly in said reverse direction, the energy of the rapidly-expanding gases is harnessed in three ways: firstly, the impact rod 48 is driven forwardly as shown in Fig. 8, delivering a sudden impact, this being the useful or output energy; secondly, the spring 55 is compressed, storing energy for the next compression cycle; and thirdly, the air in the precompression chamber 44 now sealed by the one-way reed check valve 26 is compressed to approximately half of its original volume. As the driver 12 moves past its idle position, the supply port 30 and the spray nozzle 31 are closed off, and the sear 74, cleared by the piston shaft 42, springs up into the "catch" position.As the driver 12 moves all the way forwardly, the piston 38 moves forwardly of the exhaust ports 28, thereby opening the exhaust ports 28 to the combustion chamber 46. Simultaneously, the port 54 in hollow piston shaft 42 move forwardly of the sealing small-bore cylinder 1 8 into the combustion chamber 46, thus opening a passage from the precompression chamber. At this point the compressed fuel-air mixture in the precompression chamber 44 passes through the port 52 and the recess 50 in the impact rod 48, through the hollow interior of piston shaft 42 and outwardly therefrom through the port 54 into the rear of the combustion chamber 46 forcing the exhaust gases out the forward exhaust ports 28. When the driver 12 has lost momentum, the spring 55 forces it back against the sear 74, closing off the ports 28 and 54.

Normally, the tool remains cocked (i.e. with the spring 55 compressed and with a fuel-air mixture in the combustion chamber 46). However, after storage, or running out of fuel, it may be necessary to cock the device manually. A cocking handle 90, of the type shown in Figs. 3 and 4, is provided for this purpose.

A cylindrical rod 92 of the cocking handle 90 is insertible into the small-bore cylinder 1 8 through a rear wall of the latter and into contact with the rear end of the piston shaft 42, rod 92 being bifurcated as at 94 so as to provide a clearance for the contact member 66 and the sear 74.

Forward pressure on the handle 90 moves the driver 12 forwardly until the sear 74 springs upwardly into the cylinder 1 8 in a stop position rearwardly of the piston shaft 42.

Claims

1. An impact-delivering tool of the internal combustion type and having a self-contained fuel supply, comprising a body communicating with the fuel supply and with atmosphere, a driver within the body and dividing it into a compression chamber and a combustion chamber, the driver including a piston having integral valving, fuel metering means integral with the body and driver, ignition means for igniting the fuel-air mixture for.

moving the driver, and trigger means for actuating the driver.

2. An impact-delivering tool as claimed in claim 1, wherein the ignition means is adjustable for changing the compression ratio of the fuel-air mixture in the combustion chamber.

3. An impact-delivering tool as claimed in claim 1 or 2 including a compression spring disposed wholly within the body for loading the driver.

4. An impact delivering tool as claimed in any preceding claim, wherein the ignition means comprises a piezoelectric crystal linked to a spark plug.

5. An impact delivery tool as claimed in any preceding claim wherein the ignition means comprises a microswitch linked to a spark plug.

6. An impact delivery tool substantially as hereinbefore described with reference to and as illustrated in Figs. 1 to 4 and 6 to 9 of the accompanying drawings.

7. An impact delivery tool substantially as hereinbefore described with reference to and as illustrated in Fig. 5 of the accompanying drawings.