JPS582798B2 - Teichyakuguchikomikogu - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fastener driving tools, and more particularly to high pressure tools capable of driving fasteners into hard, dense materials such as steel or concrete. It is related to.

The most powerful tools for driving or securing fasteners, such as studs, into hard or dense materials are the use of gas-generating explosives or propellants introduced directly into the piston-cylinder motor. Use charge.

This is because the rate of combustion of the gas controls the driving power available at any given time during combustion, and as a result there are differences in the energy imparted to the fastener in various operations. It means that there is a tendency.

Furthermore, the desired control of power in any given operation is achieved by using different powder charges, with the result that only rather coarse adjustments of power can be carried out.

Moreover, the cost of the individual powder charges required for each operation of the tool is somewhat greater than is desirable.

Accordingly, one object of the present invention is to provide a new and improved high power tool for driving fasteners.

Another object of the present invention is to provide a new and improved type of piston-cylinder motor having a gas generation chamber and a valve controlled by the generated gas to control the entry of the generated gas into the cylinder. The purpose of the present invention is to provide a single-stroke power plant with improved performance.

Yet another object of the present invention is to provide a new and improved single stroke power tool that uses combustible fuel to drive a cylinder-piston motor.

Still another object of the invention is that the biased main valve assembly seals communication between the cylinder and the compression chamber until the pressure of the combustion product exceeds the main valve biasing force; Subsequently, it is an object to provide a power device for a fastener driver that uses a cylinder-piston motor in which combustion gas is supplied to the cylinder to operate the cylinder-piston motor.

Yet another object of the invention is to use an aerodynamically biased main valve assembly pressurized by the gases generated within the combustion chamber to control the entry of combustion gases from the combustion chamber into the cylinder, and to control the entry of combustion gases into the cylinder. It is an object of the present invention to provide a single stroke fastener driving tool in which the air bias force can be adjusted to control the pressure applied to the cylinder.

Yet another object of the invention is to provide a new and improved control for using a combustion chamber to generate gas to drive a piston, for supplying combustible gas to the combustion chamber, and for controlling the sequence of operation of tools. A fastener driving tool having a valve assembly is provided.

In accordance with these and many other objects, embodiments of the tool include a housing having a generally vertically extending forward head portion and a rearwardly extending handle portion.

The head portion defines a combustion chamber, a cylinder in which a piston connected to the driver is slidably mounted, and a fastener housing structure in which the fastener driver is movable. .

Communication between the combustion chamber and the cylinder is normally closed by a main valve assembly having a differential piston with a small area exposed to the combustion chamber and a large area supplied with compressed air. .

The control valve assembly on the handle includes a multi-position valve that can be operated in various positions to implement a sequence of operations on the tool.

In one position, the main valve assembly is open and compressed air is supplied through the combustion chamber and cylinder to displace previous combustion gases.

In one other position, a large area surface on the piston of the main valve assembly is supplied with compressed air to close the main valve assembly, and a predetermined amount of flammable gas, such as propane gas, is supplied with compressed air to close the main valve assembly. , is fed into the combustion chamber.

In yet another location, a predetermined amount of combustible gas is supplied with compressed air to create a combustible mixture.

Operation of an electrical switch or other control device renders an ignition device, such as a spark plug or globe lug, effective to cause combustion of the flammable mixture within the combustion chamber.

The combustion gases within the combustion chamber increase in pressure until a small area surface on the valve gear of the main valve assembly generates a net force that exceeds the closing bias force from the compressed air.

At this time, the main valve assembly is moved to its open position and gas from the combustion chamber enters the cylinder to drive the piston and driver through the power stroke.

These gases are vented at the end of the power stroke and the main valve assembly is closed again by the control valve assembly in the manner described above to condition the tool for yet another cycle of sequential operation.

The cost of the fuel used to power the tool is significantly less than the cost of the powder cartridges used previously.

Moreover, by using a valved arrangement in combination with a combustion chamber, the effectiveness delivered from the tool can be increased since only high pressure gas is allowed to enter the cylinder.

Furthermore, by adjusting the pressure of the compressed air supplied to bias the main valve assembly to its closed condition, the pressure at which the combustion gases enter the cylinder can be controlled;
There will be control over the driving force created during each stroke.

Many other objects and advantages of the present invention will become apparent from consideration of the following detailed description taken in conjunction with the drawings.

Referring now more particularly to FIG. 1 of the drawings, there is shown generally designated by the numeral 20 a high-pressure driving tool for studs or fasteners embodying the present invention.

Tool 20 includes a housing 22 having a generally vertically extending forward head portion 22A with a generally rearwardly extending handle portion 22B connected to the upper end of the head portion 22A.

The head portion 22A includes a combustion chamber 24, the lower end of which communicates with the upper end of a cylinder 26, within which a piston 28 is slidably mounted, and a driver at the lower end of the piston. 30 are connected.

The driving tool 30 is inserted into the driving opening 32 in the fastener receiving structure 34.
The lower end of the structure 34 is adapted to be placed against the workpiece into which the fastener 36 is to be driven.

Main valve assembly 38 controls communication between combustion chamber 24 and cylinder 26 .

A control valve assembly 40 located in the handle portion 22B of the housing is connected to a compressor or other suitable source of compressed air 4.
A device is provided for moving and biasing the main valve assembly 38 using compressed air supplied from 2.

The control valve assembly 40 also, in three different positions thereof, combines compressed air from a compressed air source 42 to direct combustible gases into the combustion chamber 24 from a combustible gas source 44, such as propane gas. supply

When the tool 20 is in the position shown in FIG. Biased into a closed position.

A spark plug or globe lug 48 ignites the mixture inside combustion chamber 24 .

When the gas pressure generated by combustion overcomes the compressed air bias applied to main valve assembly 38, the main valve assembly is opened and the high pressure combustion products enter the upper open end of cylinder 26. , piston 28 and driver 30 during a power stroke during which fastener 36 is driven into the workpiece.

After this power stroke, control valve assembly 40 is operated to a position in which main valve assembly 38 is held open and compressed air is directed into combustion chamber 20 to expel combustion gases from tool 20.
and is passed through cylinder 26.

After the piston 28 and driver 30 have been returned to their normal positions and the fastener 36 has been manually inserted into the driver opening 32, the control valve assembly 40 is activated under the control of the ignition controller 46. Another cycle of operation of the tool 20 is possible so that it can be operated according to the sequence of positions.

The adjustment by the adjustment device 50 allows the power or gas pressure of each driving stroke to be controlled.

Referring now more particularly to the structure of housing 22, the housing includes a generally cylindrical block 52 with an interior opening defining combustion chamber 24. As shown in FIG.

The open lower end of the opening forming the combustion chamber 24 threadably receives a threaded sleeve 54 to an inner surface to which the upper end of the cylinder 26 is threadedly joined.

sleeve. The upper end of 54 includes a tapered seat surface 54A that forms a seat for main valve assembly 38.

The lower end of cylinder 26 is secured to fastener receiving structure 34 by screws.

This structure 34 is used to stabilize the tool 20 when it is placed against the workpiece and also to prevent flying debris resulting from driving the fastener 36 into the workpiece. To prevent this, it includes a cup-shaped member 56 secured in position by a set screw 58.

Main valve assembly 38 is located within combustion chamber 24 and includes both an exhaust valve portion 38A and a valve arrangement (ie, control piston portion) 38B.

The main valve assembly 38 is formed by a movable annular or cylindrical valve body 60 with a centrally located opening mounted on a central post 62 secured to the housing block 52 by a nut 64 .

To create the exhaust valve portion 38A of the main valve assembly 38, the valve body 60 includes an outwardly extending portion 60A at its lower end, and the flanged sleeve 66 includes a sleeve 60.
6 and the outward extension 60A of the valve body 60.
An annular elastic valve member 68 is inserted between the valve body 60 and fixed to the inside of the lower end of the opening in the valve body 60 with a screw.

A resilient valve member 68 seats on the valve seat surface 54A to control the entry of drive gas into the open upper end of the cylinder 26.

To create an exhaust valve section 38A for the upper end of the cylinder 26, the lower end of the center post 62 is provided with a circumferentially spaced groove 62A, and the upper inner wall of the sleeve 66 is provided with an enlarged diameter section or opening 66A. We are prepared.

In the closed position of main valve assembly 38 shown in FIG.
Groove 62A and opening 66A communicate to connect the interior of the upper end of cylinder 26 with the interior space of valve body 60.

A passageway 70 in the central column 62 is provided to communicate the opening with the atmosphere, thereby communicating the interior of the upper end of the cylinder 26 with the atmosphere.

For example, when main valve assembly 38 is moved to the open position shown in FIGS. 4 and 6, groove 62A and opening 66A are placed out of communication, and the exhaust system that includes passageway 70 and communicates with the atmosphere is Communication with either the interior of the cylinder 26 or the interior of the combustion chamber 24 is closed off.

The valve arrangement (piston portion) 38B of the main valve assembly 38 facilitates movement of the main valve assembly 38 between the closed position shown in FIGS. 1 and 5 and the open position shown in FIGS. 4 and 6. Equipped with a device for controlling.

The valve arrangement (piston portion) 38B is a piston portion 6 that is slidably mounted within a control cylinder 72 formed within the block 52 of the housing concentric with the central column 62.
Includes 0B.

Piston portion 60B includes a large area upper piston surface 60C and a small annular piston surface 60D that is in continuous communication with and exposed to combustion chamber 24.

The area of the piston surface 60D is larger than the facing surface of the flanged outward extension 60A on the body 60 of the valve, so that when the combustion chamber 24 is pressurized, the piston surface 60D and the flanged There is a net upwardly directed component force resulting from the exposed upwardly facing surface of the outwardly extending portion 60A.

Piston surface 60 attempting to move valve body 60 upwardly
The net effective area on D is small compared to the area of surface 60C.

The control valve assembly 40 receives a source 42 of compressed air to bias the main valve assembly 38 toward the closed position and to provide a means for retaining the main valve assembly in its closed position. It includes means for feeding the control cylinder 72 from the control cylinder 72 over the passage 74 in the block 52.

The difference in effective area on piston surfaces 60C and 60D is
Very high pressure gases resulting from combustion within the combustion chamber 24 can be obtained before the gases are forced into the cylinder 26 to drive the piston 28 by movement of the main valve assembly 38 to the open position.

As an example, in one tool constructed in accordance with the present invention, the ratio between the area of surface 60C and the effective area of surface 60D is about 18 to 1.

This is about 7kg/cm2 (1001b/in2)
If compressed air is introduced into cylinder 72 at a pressure of This means that it cannot be opened to allow gas to enter the cylinder 26.

By regulating the pressure of the compressed air supplied to the cylinder 72 using the regulating device 50, the pressure of the gas entering the cylinder 26 and thus the driving force achieved in a given stroke is controlled. Not only can it be controlled, but it can be controlled in small increments that could not previously be achieved with high pressure fastener driving tools.

A useful range of ratios between the area of the larger piston surface 60C and the effective area of the smaller piston surface 60D is 5 to 1.
It is conceivable to include ratios from 1 to 30 to as high as 30:1.

A control valve assembly 40 that facilitates various operations of the tool 20 is supported on the handle portion 22B of the housing 22.

Handle portion 22B includes a lower handle member 80 and an upper handle member 82, which are secured to each other and to housing block 52.

The lower handle member 80 includes a centrally located cylindrical opening 81 and a generally cylindrical body 8 therein.
4 is arranged, the inner end of which is screwed into an opening in the housing block 52 communicating with the combustion chamber 24.

A flanged or enlarged outer end portion 84A of body 84 clamps handle member 80 to housing block 52.

At its inner end, body 84 supports a check valve assembly 86 .

The check valve assembly 86 selectively supplies combustible gas and compressed air to the combustion chamber 24 at various locations in the control valve assembly 40 .

The check valve assembly 86 (FIG. 4) includes a valve cylinder 88 having different diameter portions within which slides a valve piston 90 having an enlarged head portion 90A supporting a check valve O-ring 92. It is attached so that it can move freely.

A retaining ring or washer 94 prevents ejection of piston 90 from cylinder 88 by engaging the left end of enlarged head portion 90A.

This enlarged head portion 90A prevents sealing engagement between the washer 94 and the left surface of the piston head portion 90A.
Includes spaced groove regions 90B.

When piston 90 is in the position shown in FIG. It then reaches around the head portion 90A of the piston 90 so as to be supplied to the combustion chamber 24.

The central portion of the body 84 cooperating with the handle member 80 and the opening 81 formed therein forms a combustible gas metering chamber.

More particularly, a pair of spaced O-rings 100 and 102 supported on the body 84 provide a gas metering chamber 104 that communicates with a gas inlet/outlet passageway 106 formed within the handle member 80. The central portion of the opening 81 is then sealed.

Depending on the position of control valve assembly 40, combustible gas is supplied to metering chamber 104 via passageway 106 or
Either it is discharged from the metering chamber via passage 106.

The right or outer end portion of the valve body 84 includes a device for connecting the tool 20 and control valve assembly 40 to a source 42 of compressed air.

More specifically, the compressed air inlet line 1 from the conditioning device 50
07 is joined by an opening 108 in the valve body 84 and a thread at the outer end of its outer end portion 84A.

Aperture 108 is placed in communication with a compressed air inlet passage 110 in handle member 80 via a passage 112 in valve body 84 .

Although conduit 107 is shown as being threadedly connected to body 84, a quick release separable fitting may be provided.

Handle member 82 provides a means for connecting control valve assembly 40 to a source of combustible gas 44 and also supports a manually adjustable control device that forms part of control valve assembly 40 .

More specifically, the handle member 82 includes a longitudinally extending opening 114 to the right end of which is threadedly connected one end of a conduit 116 extending to the combustible gas outlet of the regulating device 50.

Therefore, the right end portion of the opening 114 is normally supplied with flammable gas.

Slidingly mounted within the slightly enlarged portion of the aperture 114 is a cylindrical valve piston 118 with an adjustment member 120 at one end thereof extending through a slot 122 out of the aperture 114 to the upper surface of the handle member 82. It is joined to extend the

Valve piston 118 supports three spaced O-rings 124, 126 and 128.

When the valve piston 118 is moved to its various positions, the O-rings 124, 126 and 128 cooperate with a plurality of passageways 130, all of which correspond to different sets of passageways within the handle member 80. A combustible gas is supplied to the passageway within the handle member 80 from the right end portion of the opening 114 to selectively interconnect the mating elements.

In the full description, the various components of control valve assembly 40 are shown in FIG. 4 of the drawings.

In this figure, passages 96 and 110 are shown in schematic form to simplify subsequent understanding of the operation of control valve assembly 40.

Figures 1-3 of the drawings illustrate the configuration of these passages.

Generally, various control passageways are provided in the lower handle member 80.
It is formed by providing a flat top surface 80A (FIG. 2) and by forming a passageway within the flat top surface.

Upper handle member 82 also has a flat bottom surface that matches the upper surface and a sealing gasket 131 is interposed between the flat surfaces of handle members 80 and 82.

A plurality of machine screws 132 secure the two handle members 80 and 82 to a sealing gasket 131 inserted between them.
fixed together with.

Positioning and attachment of upper handle member 82 to housing 22 is facilitated by a dowel or pin 134 extending between the left end of aperture 114 and an aligned aperture 136 in housing block 52.

Referring now to FIG. 2 of the drawings in greater detail, an air inlet passageway 110 extending over a relatively large area is connected to the handle member 8.
a groove in the flat upper surface 80A of the 0 and culminating at its right end into a vertical passage communicating with an opening 81 in the handle member.

A vertical portion of passageway 110 receives compressed air supplied through an opening 112 in body 84 .

Similarly, check valve inlet passage 96 over a relatively large area
consists of a groove in the flat upper surface 80A of the handle member 80.

At its left end, a vertical portion of passageway 96 places it in communication with an inlet passageway 98 to check valve assembly 86 .

The gas passage 106 extending into the metering chamber 104 consists of a vertical passage or hole.

The flat top surface 80A also includes an elongated slot 138 that directs combustible gas from the opening 114 to the passageway 106.
It is used for transferring to the measuring chamber 104 beyond the

Control valve assembly 40 also includes further devices for controlling the supply of compressed air to passageway 74 and, therefore, to control cylinder 72.

More specifically, the planar upper surface 80A of the lower handle member 80 includes a passageway 140, the right end of which is selectively supplied with compressed air under control of the position of the valve piston 118.

The left end of passageway 140 is aligned with one end of passageway 141 (FIG. 3) in upper handle member 82.

Passageway 141 extends to a port at the end of handle member 82 that is aligned with a port to channel 74 in housing block 52 .

Ignition control device 46 includes a device for selectively igniting or initiating combustion of a mixture of gas and air within combustion chamber 24 .

The ignition control device 46 includes an electric switch 142 (
1 and 3).

The trigger 144 is pivotally mounted between a pair of depending supports 146 by a pivot pin 148 (a third
figure).

The depending support 146 forms part of a support bracket to which the electrical switch 142 is secured, and the bracket is secured to the housing block 52 by a plurality of machine screws 150 in sequence.

Switch 142 controls the connection of spark plug 48 to a source of electrical current across the appropriate conductor (not shown).

Spark plug 48 communicates with the interior of combustion chamber 24 beyond combustion chamber extension 24A (FIG. 1).

Therefore, when trigger 144 is rotated counterclockwise about pivot pin 148 to lift actuator 142A, switch 142 is operated to energize spark plug 48, causing combustion chamber 24 resulting in ignition of the flammable mixture inside.

To prepare for operation of tool 20, an estimate is made of the power required to drive fastener 36 into the workpiece.

Adjustment device 50 is adjusted to create the necessary drive force for the fastener driving operation.

Regulating device 50 may be of any of many types well known in the art and essentially adjusts the pressure of compressed air from compressed air source 42 and the pressure of combustible gas from source 44. are maintained in a ratio to each other that provides efficient combustion within combustion chamber 24.

In one tool 20 constructed in accordance with the invention using gas source 44, conditioning device 50 may, for example, direct compressed air from source 42 into tube 107 at approximately 7 kg/cm2 (100 liters).
b/in2) and propane gas from source 44 to line 116 at approximately 0.35 kg/cm2 (5 lb/in2).
).

If, as in the representative example above, it is assumed that an approximately 18 to 1 ratio exists between the effective areas of piston surfaces 60C and 60D, then the pressure of the combustion gases inside combustion chamber 24 is , approximately 126 kg/cm2 (1800 lb/in2) must be reached before main valve assembly 38 is opened to allow generated gas to enter cylinder 26.

The same ratio of compressed air to combustion gas pressure is maintained by the regulating device 50 at other settings.

As an example, if a greater driving force is desired, the pressure of the air supplied to the control cylinder 72 may be increased to approximately 14 kg/cm2 (200 lb/in2);
The pressure of the propane gas supplied to the pipe line 116 by the source 44 is approximately 0.7 kg/cm2 (101b/in2).
It is raised to.

In this setting, the pressure of combustion gases within combustion chamber 24 required to cause opening of main valve assembly 38 is approximately 126 kg/cm
Approximately 252kg/cm from m2 (18001b/in2)
2 (36001b/in2).

At the end of each driving stroke of the tool 20 (FIG. 7), the piston 28 is at the end of its power stroke, in which position the bottom surface of the piston 28 is exposed to an elastic force disposed inside the lower end of the cylinder 26. It rests against the buffer 152 of.

In this position, the interior of the cylinder 26 is
8 and to the atmosphere through a plurality of ports 154 designed to vent the combustion gases through the cylinder 26 at the conclusion of the power stroke of the driver 30.

The lower end of cylinder 26 also includes a plurality of circumferentially spaced openings of larger area designed to assist in exhausting air from cylinder 26 below the piston during the power stroke of piston 28. 156 included.

A generally cup-shaped deflector 158 is provided to deflect the hot gas discharged from the cylinder 26 toward the workpiece and away from the operator.

Control valve assembly 40 is operated to its first position in which the interior of combustion chamber 24 and cylinder 26 is cleaned of combustion gases and metering chamber 104 is cleaned of combustible gases from source 44. Supplied.

More specifically, in this first position, the valve piston 1
Adjustment member 120 on 18 is moved to the rightmost position shown in FIG.

In this position, propane gas from line 116 contained within opening 114 passes through first passageway 130 into slot 138 and then through passageway 130 communicating from this slot. The space enclosed by the two O-shaped rings 126 and 128 on the valve piston 118 is then reached.

The combustible gas flows downwardly through passage 106 such that it accumulates inside metering chamber 104 .

For example, about 0.35 kg/cm2 (about 51 b/in2)
This combustible gas, at a pressure of 1,000 yen, also flows through an opening 160 in the body 84 so that it accumulates inside the right end of the cylinder 88 in the check valve assembly 86.

This combustible gas biases the valve piston 90 to the leftmost position determined by the engagement of the piston's enlarged head portion 90A with the retaining ring 94.

This ensures that check valve assembly 86 is opened.

At the position setting of the control valve assembly 40, approximately 7 kg/cm
2 (approximately 1001 b/in2)
07 to opening 108, passages 112 and 110, connected multiple passages 130, check valve inlet passage 96, opening 98
, cylinder 88 and then past enlarged head portion 90A on piston 90 to combustion chamber 24.

At the location of control valve assembly 40, passage 74 is connected to passage 1.
40 reaches a passage 130 located to the left of O-ring 124 and is communicated with the atmosphere beyond passage 140.

The upper surface 60C of the piston portion 60B is in communication with the atmosphere so that the compressed air supplied to the combustion chamber 24 moves the main valve assembly 38 upwardly to the position shown in FIG.

This flows through the combustion chamber and cylinder 26 such that the compressed air supplied to the combustion chamber 24 via the check valve assembly 86 is discharged through the opening 154, the opening of which the piston 28 is shown in FIG. It means that it is open because it is in the lowest position.

The flow of compressed air cleans the interior of combustion chamber 24 and cylinder 26 of combustion gases resulting from previous operation of tool 20.

The operator moves control valve assembly 40 to its second position, in which main valve assembly 38 is moved to its closed position and combustible gases from metering chamber 104 are discharged. , from this metering chamber to the combustion chamber 24.

This second position is shown in FIG.

In this position, adjustment member 1-20 is positioned approximately midway along the length of slot 122.

To aid in positioning the control valve assembly 40, the slot 122 has a continuous slot and opening 114 along one edge.
to provide a device for retaining the control valve assembly 40 in a desired position against a biasing force applied to the right end of the valve piston 118 by a combustible gas disposed to the right of the piston within the valve piston 118; and a series of three notches along opposite edges.

In the position shown in FIG. 5, the type 0 ring 124 is
Control cylinder 7 over atmosphere and passages 74 and 140
Close the communication with the upper end of 2.

In this position, the type 0 rings 124 and 126 are
Communication is established through a plurality of adjacent passageways 130 for supplying pressurized fluid from passageway 110 to passageways 140 and 74.

This pressurized fluid accumulates within control cylinder 72 above piston portion 60B and moves valve body 60 to its lower position so that main valve assembly 38 is placed in its closed position.

In this position, the resilient valve member 68 is in contact with the cylinder 26.
is seated on the valve seat surface 54A so as to close off communication between the interior of the valve and the combustion chamber 24.

Further, the upper inside of the cylinder 26 includes a passage 70 and a valve body 6.
Openings and grooves 62A and openings 66A inside 0
vented across the exhaust system containing the

When the control valve assembly 40 is moved to this intermediate or second position, the combustible gas within the metering chamber 104 is also directed to the combustion chamber 24, which is connected to the cylinder 26.
It is sealed from communication with.

More specifically, when valve piston 118 is moved to the position shown in FIG.
8 and a passage 106 extending to the metering chamber 104 is closed off.

Type 0 rings 126 and 128 place passageway 106 in communication with check valve inlet passageway 96 via a pair of passageways 130 shown.

Therefore, the combustible gas is
and 98 to the cylinder 88.

Since the inside of the combustion chamber 24 is generally at atmospheric pressure,
The pressurized combustible gas in cylinder 88 displaces valve piston 90 to the position shown in FIG. 5 so that the combustible gas enters and becomes trapped inside combustion chamber 24.

With the control valve assembly 40 held in this intermediate position, the operator moves the piston 28 and driver 30 into the normal position shown in FIG. return to position.

The operator positions the fastener 36 at the lower end of the driving aperture 32 and positions the tip structure of the tool 20 adjacent the workpiece.

Tool 20 is ready to be operated to its final or third position in which control valve assembly 40 prepares the tool for operation.

Accordingly, by manipulating adjustment member 120, the operator moves control valve assembly 40 to the final position shown in FIG.

In this position, metering chamber 104 is refilled with combustible gas and compressed air is supplied to combustion chamber 24 via check valve assembly 86 to create a flammable mixture, followed by Stop valve assembly 86 is closed.

In the firing or third position shown in FIG.
maintains a supply of compressed air to control cylinder 72 so that main valve assembly 38 is maintained in its closed position.

Type 0 ring 128 passes over adjacent passage 130 so that combustible gas from opening 114 is fed back across passage 106 to fill metering chamber 104 .

This gas also applies a low pressure bias force to the small area right end portion of the piston 90 of the check valve assembly 86 through the opening 160.
pass through.

Type 0 rings 126 and 128 connect two adjacent passages 13
0 and the compressed air inlet passage 110 is placed in communication with the check valve inlet passage 96 so that the compressed air is transferred to the combustion chamber 24.
through a check valve assembly 86 to pressurize the combustible mixture and supply the combustible mixture to the interior of the combustion chamber 24.

As mentioned above, the combustion chamber 24 previously weighed approximately 0.35 kg.
It was pressurized with propane gas at 51 b/in2.

Therefore, in this example approximately 7 kg/cm2 (100
1b/in2) is supplied to the check valve assembly 86.
When the combustion chamber 24 is supplied through the
It is pressurized to 2 (1001 b/in2) and contains approximately 5 parts of propane gas to 95 parts of air.

When the combustion chamber 24 is pressurized, the check valve assembly 86
is closed by movement to the position shown in dashed lines in FIG.

More specifically, each side of the enlarged head portion 9OA of the piston 90 within the check valve assembly 86 weighs approximately 7 kg/cm2 (approximately 100 kg/cm2).
lb/in2) pressure.

However, the right end of the piston 90, which communicates with the inside of the metering chamber 104 via the passage 160, weighs approximately 0.35 kg/cm2 (approximately 5 kg/cm2).
1b/in2).

Therefore, a net force is created that moves piston 90 to the right to close off communication between combustion chamber 24 and control valve assembly 40.

The tool 20 is now ready to be ignited because the main valve assembly 38 is in its closed position and a combustible mixture has been delivered to the combustion chamber 24.

The operator rotates trigger 144 counterclockwise about pivot pin 148 to the position shown in phantom in FIG. 6.

This is the switch operator 1 that operates the electric switch.
42A, so that spark plug 48 is energized.

After a short enough period of time to allow the spark plug 48 to reach the ignition temperature, the gaseous mixture inside the combustion chamber 24 is rapidly ignited, and this gaseous by-product increases the pressure inside the combustion chamber 24. do.

In the example where there is an 18 to 1 ratio between the effective areas of surfaces 60C and 60D and compressed air at about 7 kg/cm2 (1001 b/in2) is supplied to control cylinder T2, the gas inside combustion chamber 24 is They are about 126k
When g/CTL (1800 lb/in2) is reached or slightly exceeded, it creates a force on the piston surface 60D that momentarily pushes the valve body 60 upwardly as shown in FIG. move it to the specified position.

At this time, the gaseous combustion gas weighs approximately 126 kg.
/cm2 (18001b/in2) or above, enters the upper end of cylinder 26 and drives piston 28 and driver 30 downwardly through a power stroke during which fastener 36 , driven into the workpiece.

By expanding the gaseous combustion gases from the combustion chamber 24 into the cylinder 26 and by venting the interior of the cylinder 26 when the piston reaches its lower position shown in FIG. The differential force opening assembly 38 disappears, and the biasing force continuously applied to control cylinder 72 acts against piston surface 60C to move main valve assembly 38 to its closed position.

When the operator releases trigger 144 to release switch 142, energization of spark plug 48 ends.

The control valve assembly 40 can then be operated through the same three-step sequence described above in connection with the other manual operations described above to prepare the tool 20 for its next operation.

Because the tool 20 uses only a small amount of low-cost fuel, such as propane gas, and a small amount of compressed air, the tool 20
The cost of each ignition stroke is significantly less than with the use of powder charges or cartridge-type tools.

Furthermore, by operating the adjusting device 50, the control cylinder 7
The pressure of the compressed air supplied to the combustion chamber 24 can be varied to control the pressure at which the combustion gases discharged from the combustion chamber 24 are forced into the interior of the cylinder 26.

By adjusting this pressure, the power induced from tool 20 can be easily adjusted.

Additionally, regulator 50 regulates and maintains the pressure of compressed air from source 42 and combustible gas from source 44 so that the proper flammable mixture is maintained at control valve assembly 40 at various settings of regulator 50. is constantly supplied to the combustion chamber 24 by.

Obviously, for different combustible gases, the ratio of compressed air to combustible gas can vary, and these differences are easily adjusted in the regulating device 50.

Although the invention has been described with reference to a single illustrative embodiment, numerous other variations and embodiments are apparent to those skilled in the art that would fall within the spirit and scope of the principles of the invention. It should be understood that this can be considered by those skilled in the art.

[Brief explanation of drawings]

1 is a longitudinal sectional front view of a power fastener driving tool embodying the present invention; FIG. 2 is a fragmentary horizontal sectional view taken along line 2--2 of FIG. 1; and FIG. , a fragmentary longitudinal side view taken along line 3-3 of FIG. 1, and FIG. 4 a fragmentary enlarged longitudinal section illustrating the control valve assembly in a first position for performing tool cleaning. Front view, FIG. 5, is a fragmentary enlarged longitudinal section similar to FIG. 4 illustrating the control valve assembly in another second or intermediate position for supplying combustible gas to a combustion chamber within the tool. FIG. 6 illustrates the control valve assembly in a third position for supplying compressed air to fuel within the combustion chamber and a fourth illustrating the tool at the moment immediately following ignition of fuel within the combustion chamber. and FIG. 7, a figure similar to FIG. 5, is a fragmentary enlarged longitudinal sectional front view illustrating the drive piston and driver at the end of the power stroke. 22...Housing, 22A...Head part, 22B...Handle part, 24...Combustion chamber, 26...Cylinder, 28
... Piston, 30 ... Driver, 34 ... Fastener housing structure, 38 ... Main valve assembly, 38B ... Main device (piston portion), 40 ... Control valve assembly, 42 ... Compressed air source, 44... Flammable gas source, 46... Ignition control device, 48
... Spark plug, 50 ... Adjustment device, 60C ... Piston surface, 60D ... Piston surface, 104 ... Flammable gas metering chamber, 118 ... Manual control device.

Claims (1)

Claims: 1. A housing 22 having a forward head portion 22A and a rearwardly extending handle portion 22B, a source 42,44 of combustible gas and compressed air, and controls located on the handle portion 22B of said housing 22. a regulator 50 that is connectable to the valve assembly 40; the control valve assembly 40 is in communication with the regulator 50; and the regulator 50 is connectable to the control valve assembly 40. the control valve assembly 40 and the housing group 22;
a main valve assembly 38 located within the main valve assembly 3;
8 and a combustion chamber 24 within the housing 22 in communication with the control valve assembly 40 for controlling the flow rate of the gas from the regulator 50 to the combustion chamber 24; a cylinder 26 placed in the head portion 22A; a driving piston 28 that is slidable within the cylinder 26; and a fastener located in the head portion 22A. The storage structure 34, the fastener driver 30 that is movable relative to the fastener storage structure 34, and the driving piston 28 are placed in the fastener storage structure 34. The attached fastener 36 is attached to the head portion 22A.
The main valve assembly 38 is operable to move the driver 30 relative to the fastener housing structure 34 for driving from the combustion chamber 24 and the cylinder. 26 and the combustion chamber 24.
and a closed position in which communication between the main valve assembly 38 and the cylinder 26 is occluded;
is arranged to slide within said cylinder 26 when said control valve assembly 4 is in its released position;
0 is operable to repeatedly move the main valve assembly 38 between the open position and the closed position, and when the main valve assembly 38 is in the closed position. , igniting the combustible gases in the combustion chamber 24 to create high pressure combustion gases communicateable to the cylinder 26 for actuating the fastener when the main valve assembly 38 is in its open position. Ignition device 46 for actuating piston 28.
48, and a power-operated fastener driving tool. 2. In the fastener driving tool according to claim 1, the main valve assembly 38 includes a pair of piston surfaces 60C, 6
0D; the valve device 38B is movable in response to a force on either of the surfaces 60C, 60D; One surface 60D is in communication with the combustion chamber 24, and the other of the piston surfaces 60C is connected to a source 42 of compressed air via the regulator 50 and the control valve assembly 40. for coupling and to the combustion chamber 24,
via the regulating device 50 and the control valve assembly 40;
a device for coupling a source 44 of combustible gas, the combustion gases in the combustion chamber 24 acting on one of the piston surfaces 60D and on the other of the piston surfaces 60C; moving the main valve assembly 38 to its open position against the pressure of compressed air so that the combustion gases can drive the fastener actuating piston 28; tool. 3. The fastener driving tool of claim 1, wherein the control valve assembly 40 includes a manually operable control 118 movable to three different positions; The operable control device 118 controls the cylinder 26.
the manually operable control device 118 is operable in a first of the three positions for cleaning the interior of the piston; Valve device 38
B is actuatable in a second of the three positions to move the combustion chamber 2 to its closed position;
4; operable in a third of the three positions for supplying a mixture of flammable gas and compressed air to a combustible gas; A fastener driving tool comprising: a gas metering chamber 104; and a device for coupling the metering chamber 104 to the combustion chamber 24 in the third position of the manually operable control device 118.