JP2003056730A - Variable volume valve for combustion powered tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve assembly with a variable flow measuring chamber for a combustion powered tool. SOLUTION: The assembly is provided with a housing partitioning the measuring chamber having an inside volume and including an entrance and an exit, and a plunger constituted to reciprocate to the chamber for adjusting the inside volume of the measuring chamber. Preferably, the plunger is adjustable by a user for changing the fuel quantity retained in the measuring chamber. In the housing, a first valve control controls a fluid flow passing through the entrance, a second valve control controls the fluid flow passing through the exit, and an operating assembly is connected to the valve and continuously operable from a first position where a first spring eccentric valve is opened and a second spring eccentric valve is closed, to a second position where the both of the first and the second spring eccentric valves are closed, and to a third position where the first spring eccentric valve is closed and the second spring eccentric valve is opened.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to constant volume valves for combustion powered tools such as power assembly tools. In particular,
It relates to a constant volume valve assembly that meters the volume of fluid prior to flowing into the combustion chamber. It should be noted that this application is a co-pending US Serial No. 09 / 849,606 partial continuation application filed May 4, 2001 for constant volume valves for combustion powered tools.

[0002]

BACKGROUND OF THE INVENTION The present invention also relates to a pneumatically driven, combustion powered or other rapidly actuated fastener drive tool of the type using an accessory fastener. Generally, Nikolich, U.S. Reissue Patent No. 32,452, and Nikorich, U.S. Pat. No. 4,52, incorporated herein by reference.
2,162, Nicorich U.S. Pat. No. 4,483,4.
74, Nicorich U.S. Pat. No. 4,403,722.
And Wagdy U.S. Pat. No. 4,48
As illustrated in US Pat. No. 3,473, a combustion-powered fastener drive tool has a combustion chamber, which is formed by a cylinder body and a valve sleeve arranged to open and close the combustion chamber. . Generally, similar combustion-powered nail and staple drive tools are commercially available under the trademark IMPULSE from ITW Paslode (a division of the Illinois Tool Company), Vernon Hills, Illinois.

In such a tool, it is beneficial to apply a steady force to each fastener during the drive process that is driven into the workpiece. Measuring the amount of fuel delivered to a combustion-powered tool or the amount of compressed gas delivered to a pneumatically-powered tool helps to provide a steady force. A combustion-powered fastening tool that opens a valve and measures fuel for a length of time defined by the movement of a cam is described in U.S. Pat. No. 4, Cotta.
721,240. Fuel flows through the fuel valve to the combustion chamber tubes, the amount of which equals the amount of passage through the needle valve during the time the fuel valve is open. Flow rate measurements over time will result in the amount of fluid delivered to the tool varying as the fluid flow rate changes. When the fuel cylinder is emptied, the cylinder pressure drops and the fluid flow rate changes. Similarly, variations in pressure or flow at a common source of pneumatic fluid will also produce variations in the amount of power delivered at each fill of the cylinder.

Control of fuel entering the combustion chamber by a valve assembly is described in US Pat. Nos. 655,996 and 1,293,8.
58. Both citations disclose a pressurized fluid inlet valve and a fluid outlet valve surrounding a machine supply passage. The high pressure fluid is supplied to the machine to power it through an inlet valve,
Following power delivery, when it returns from the machine it is discharged through the outlet valve. No citation teaches the use of such devices for making steady state measurements of fluids. After combustion of the fuel or expansion of the high pressure fluid, the fluid no longer serves to power the tool and the measurements at this point are not effective.

US Pat. No. 4,913,331 to Utsumi
The publication describes a device which uses a metering chamber to which a metered amount of fuel is supplied and which uses an internal combustion engine to drive a piston.
A fuel piston including a metering chamber is reciprocable within the fuel cylinder. The fuel inlet channel and the fuel outlet channel are arranged such that movement of the piston between the inlet channel and the outlet channel causes the metering chamber to fill or empty.
A seal is located on one side of the metering chamber between the fuel piston and the cylinder to prevent fuel from leaking from the pressurized fuel source to the combustion chamber. Since they are in constant contact with the faces of the cylinders, the constant movement of the pistons causes premature wear of these seals.

[0006]

One disadvantage of the operation of conventional combustion power tools is that the pressure of the pressurized fluid drops when operated at relatively low temperatures, for example below 0 ° C.
A large pressure difference is created between the atmosphere and the fuel. At this low pressure, the fuel does not disperse rapidly through the proper passages and into the combustion chamber. This state delays combustion and impairs tool operating efficiency.

Another operating drawback of conventional combustion-powered tools is that they use less air for combustion when used at higher altitudes. As a result, when used in such high altitudes, conventional combustion-powered tools with constant volume fuel metering valves produce an excessively high concentration of air-fuel mixture in their combustion chambers, which results in igniter fouling and other Driving difficulty may occur. Therefore, there is a need for a combustion powered tool with a fuel metering valve that has the ability to regulate the amount of fuel in the combustion mixture.

Accordingly, it is an object of the present invention to provide an improved metering of fuel for devices such as combustion powered tools to generate a constant drive force. Still another object of the present invention is to improve the quantitative measurement of fluid in a compact space. Yet another object of the present invention is to provide an improved metering valve assembly in which the seal does not constantly wear against its sealing surface. Another object of the present invention is to provide an improved metering valve assembly that facilitates fuel movement even when the fuel pressure is reduced, such as when the tool is exposed to low temperatures. . Yet another object of the present invention is to provide an improved metering valve assembly that has the ability to condition the fuel mixture, such as when the tool is operated at relatively high elevations.

[0009]

These and other objectives include:
Satisfied or overcome by this device for metering a metered fluid to provide steady energy to a tool. This device is most useful when used in a portable fastening tool that is powered pneumatically or by utilizing an internal combustion engine.
In the preferred embodiment, the valve and control mechanism configuration ensures that there is a delay between the closing of one valve and the opening of the other valve to ensure that the fluid is metered before flowing towards the downstream combustion chamber. To do.

In particular, the present invention provides a variable metering chamber, and a valve assembly for a combustion powered tool includes a housing having an interior volume and forming a metering chamber including an inlet and an outlet, and an interior volume of the metering chamber. A plunger configured to reciprocate relative to the chamber for adjustment. The plunger is preferably user adjustable to change the volume of fuel held in the metering chamber. Within the housing, the first valve control controls the flow rate through the inlet, the second valve control controls the flow rate through the outlet, and the actuation assembly in communication with the valve causes the first valve to open and From the first position with the two valves closed to the second position with both the first and second valves closed, and to the third position with the first valve closed and the second valve open. Can be operated sequentially.

The metering valve also produces a consistent amount and quality of fuel or fluid each time the tool is ignited, thus providing a steady drive force by the fastener drive tool. The fluid delivery to the power tool of the present invention is measured in volume rather than time, providing a more accurate and more consistent delivery of power to the tool. As the pressure changes, the molecules are packed with greater or lesser density, which changes the fluid density within the device. However, in the flow system, as the pressure drop across the metering valve fluctuates, so does the flow rate. As long as the constant volume chamber is filled within the time the inlet valve to the metering chamber is open, changes in flow rate have no effect on the metering system.

Furthermore, the arrangement of the metering chamber and the spring-biased valve in the present invention results in a compact use of space, which may be useful for compact, portable tools. Due to the arrangement of the valves in a straight line and the inclination angle of the combustion chamber passage, the distance between the compressed fluid source and the combustion chamber is shorter than other structures.

It is also advantageous to use a spring biased valve to control the fluid flow rate. The valve seat, which forms a seal with the inlet and outlet of the metering chamber, contacts the chamber wall only for a relatively short time. There is no constant rubbing of the seal with the adjacent wall when the valve opens and closes. This prolongs the life of the seal.

Another advantage of this valve assembly is that at least the disk that facilitates the flow of fuel into the combustion chamber passages, even in operating conditions where fluid flow is impaired, such as outside operating temperatures below freezing. That is, it is suitable for one spring-biased valve.

Yet another feature of this valve assembly is that the valve assembly is configured to introduce an inherent delay in the operation of the upper and lower spring-loaded valves, with the lower valve delivering fuel to the combustion chamber. This ensures that the planned amount of fuel is retained in the metering chamber before it is released. In the preferred embodiment, this delay is achieved by a deliberately loose mating engagement between the tongue of the actuator pivot link arm and the notch of the actuator control arm. This loose engagement results in a slight "rest" in actuation of the spring-loaded valve without continuous movement of the actuator control arm during continuous movement of the pivot link arm due to engagement of the tool with the workpiece. Make sure to cause. In this way, a consistent amount of fuel that is temporarily retained is maintained.

Yet another feature of this valve assembly is that the valve features a regulation that changes the amount of fuel flowed to the combustion chamber during each ignition cycle. This is done in the preferred embodiment by providing an adjusting shaft that can be threaded into the fuel metering chamber by the user to reduce the volume of the chamber, thereby reducing the space available for incoming fuel. Will be realized. In this way, when more fuel or rich mixture is desired, the shaft is retracted away from the metering chamber to increase chamber volume. A lean fuel mixture is obtained by advancing the shaft into the fuel metering chamber.

Yet another feature of this valve assembly is that the adjustment shaft described above can be replaced by an electric heating element when the tool is used in cold conditions of the type which causes low fuel pressure. It means that you can do it. The heating element heats either the fuel metering chamber itself or the enclosed portion of the valve housing.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, a constant volume valve assembly and a metering chamber are shown generally at 10. In the following description, the terms "upper" and "lower" refer to the assembly in the orientation shown in the drawings. However, the assembly is contemplated for use in various locations, as is well known in the art. The valve assembly 10 is particularly useful for pneumatic or combustion powered tools (not shown) having a valve housing 12 into which the fluid to be metered is injected under pressure. The valve assembly 10 supplies a fixed amount of fuel to the tool combustion chamber (not shown). Alternatively, the valve assembly 10 also meters compressed air that expands to provide power to the pneumatic tool. The valve assembly 10 can be used with any tool or device that would benefit from a stable, uniform supply of compressed fluid.

The housing 12 of the valve assembly 10 includes at least two spring-biased valves, a first spring-biased valve 16 and a second spring-biased valve 16, which regulate fluid flow to the inlet 20 and outlet 22 of the metering chamber 24, respectively. The spring biasing valve 18 of FIG. The metering chamber 24 is defined by the housing 12 and has an inlet 20 and an outlet 22 and optionally one or more ports, as described below. Neither the shape of the metering chamber 24 nor the position of the inlet 20 or outlet 22 is particularly important.
However, it is preferred that the inlet 20 and outlet 22 be located at opposite ends of the metering chamber 24. In this arrangement, the spring biased valves 16, 18 are preferably substantially coaxial to save space. In this preferred configuration, the weighing chamber 2
The fluid flow through 4 flows from the inlet 20 to the outlet 22 substantially parallel to the axis of the spring biased valves 16,18.

The metering chamber 24 may be any type of chamber capable of providing a constant volume space for metering fluid, wherein the volume of fluid collected in the metering chamber is the volume of fluid discharged from the metering chamber. Means equal to. The pressure remains constant while the fluid is enclosed in the metering chamber 24. The metering chamber 24 may be a separate container or may be a void 24 in the housing 12. The housing 12 also
Generally, a pressurized fuel can 28 (shown in FIG. 1) and a spring biased valve 1
It is also used to support other components of the propulsion device, such as 6,18. The metering chamber 24 is preferably stationary with respect to the housing 12.

The volume of the metering chamber 24 is preferably constant, but is optionally adjustable, for example by the movement of a movable wall or the opening of a valve leading to an additional chamber (not shown). However, its utility for metering purposes depends on the ability to maintain the chamber 24 at a constant volume until the setting, valve or adjustment is purposefully changed.

Each of the spring biased valves 16, 18 preferably includes a conical seat 30, 32, rods 34, 36 and a spring 38 ,.
40 respectively. Although described with respect to the relationship of the first spring-loaded valve 16, it should be understood that the following description also applies to corresponding portions of the second spring-loaded valve 18. A seat 3 for sealingly engaging the inlet 20 of the metering chamber 24 when the spring biased valve 16 is in the closed position.
0 has a size and a shape. Movement of seat 30 between the open and closed positions is controlled by rod 34. Spring 38
Is an economical way of energizing the valve, but the use of other energizing devices is also contemplated. The spring 38 is used to bias the valve 16 towards the closed position. Springs 38, 40
Each has a locking end 42, 44 and a movable end 46, 48, respectively. The movable end 46 tends to exert a force on the seat 30 and move it towards the metering chamber 24 by the force of the spring 40 acting against the locking end 42. Although the locking end 42 is directly locked to the housing 12, the locking end is preferably seated in a chamber as detailed below.

The fluid is supplied to the housing 12 under pressure. It is generally preferred that the tool be portable, in which case the fluid is supplied from a pressure can 28 which is mounted inside or outside the tool. When the tool is used in a store or other location capable of supplying large volumes of pressurized fluid, the fluid is preferably made available to the tool by a hose or similar device (not shown). The valve assembly 10 of the present invention can be used in any of these situations and is contemplated for use in either setting. Since temperature and pressure affect the density of any fluid, these factors should be kept as constant as possible to minimize fluctuations in the amount of feed fluid.

Prior to entering the valve assembly 10, the fluid preferably flows through the filter 50 (FIG. 2) to minimize unwanted contaminants. The filter 50 is preferably located at one end of a nipple 51 that fits into the can 28 for sealing engagement. After passing through the filter 50, the fuel passes through the upper passage 52.
Move in. The upper passage 52 extends from a source of pressurized fluid, such as a pressurized can 28, to the inlet 20 of the metering chamber 24. In order to achieve the most invariant amount of fluid, the upper passage 52 is preferably wide enough to achieve a consistent supply pressure before the first spring biased valve 16 closes.

In some cases, it may be desirable to provide an upper chamber 54 to store the pressurized fluid. For example, if the flow rate of the fluid is low, the fluid accumulates in the upper chamber 54 resulting in a burst of fluid entering the metering chamber 24 when the inlet 20 is open. The fluid discharged from the measuring chamber 24 flows into the lower chamber 56. Metering is accomplished by opening and closing the first and second spring biased valves 16, 18 by the actuation assembly 60. The actuation assembly 60 may be any mechanism capable of opening and closing the first and second spring biased valves 16, 18 according to a particular sequence that allows for metering within the metering chamber 24. Although a mechanical linkage is the preferred form of actuation assembly 60, one or more computer controlled cams are an example of an alternative configuration acceptable.

In the preferred embodiment, the actuation assembly 60 is connected to the upper arm 62 which is connected to the rod 34 of the first spring energized valve 16 and to the rod 36 of the second spring energized valve 18. A lower arm 64 and a C-shaped actuating arm. The upper arm 62 and the lower arm 64 are connected to each other by a control arm 66 (FIG. 1). The notch 67 of the control arm 66 is engaged by a pivot link arm 68 which is pivotally engaged with the housing 12 at point 68a. The special engagement between the link arm 68 and the notch 67 is due to the tongue 69. The control link arm 68 is operated by the movement of a valve front linkage (not shown) whose construction and operation is disclosed in the Nikolish patent incorporated by reference.

An important feature of this actuation assembly 60 is the movement of the control arms 62, 64, 66 and the upper and lower spring biased valves 1.
That is, a fixed amount of pressurized fluid is temporarily held in the metering chamber 24 due to a delay in the operation of 6 and 18. This delay is caused, in part, by the loose mating engagement of tongue 69 and notch 67. In the preferred embodiment, the tongue 69 has a reduced area as compared to the notch 67 so that the control link arm 68 does not move the control arms 62, 64, 66 and the control link arm 68 has its arcuate shape. Can move slightly along the path of travel. The looseness of engagement of the tongue 69 with the notch 67 or "slow pinness" may vary depending on the application, as the particular configuration of the mating engagement, including having the notch in the arm and the tongue in the control arm 66, changes. I can.

Depending on which valve is open and which is to be closed, actuation assembly 60 causes first and second spring biased valves 16, 18 to either be in the first valve sequence or the second valve sequence. move. The valve sequence is determined by the combustion cycle in the case of combustion tools or the impact cycle in the case of pneumatic tools.

Turning now to FIGS. 3A-3C, the valve sequence is described. The start of the first valve sequence is defined when the tool is between uses. In this position, the tool has stored power and is ready for use, but has not yet contacted the workpiece driving the fastener. At this time, actuation assembly 60 is in the first position depicted in FIG. 3A and arm 62 is at a maximum distance from the opposing wall of housing 12. The first spring bias valve 16 is in the open position and the second spring bias valve 18 is closed. Aisle 52
The metering chamber 24 is filled with fuel or fluid by communicating with the cartridge 28 through.

In the first valve sequence, the first spring energized valve 16 moves from the open position to the closed position and the second spring energized valve 18 opens but the second valve is closed until the first valve is completely closed. Does not start to open. This first valve sequence is generally triggered by some stimulus in preparation for firing the tool. To obtain the force to drive the fastener, the metering fluid is moved to a position that releases that force, ie fuel is moved into the combustion chamber or air is moved into the expansion chamber. This sequence is preferably initiated by any preparatory mechanism, such as contacting the tool with the workpiece, initiating the pressing of the inducing mechanism or the like. If a combustion-powered assembly tool is used, the filling of the combustion chamber occurs when the workpiece contact member contacts the workpiece, causing fuel to flow from the metering chamber 24 through the lower chamber 56 to the combustion chamber. It allows passage into passage 70 and finally into a combustion chamber (not shown). In the preferred embodiment shown, the sequence is initiated by contacting the tool with the workpiece, which is the pivotal link arm 6.
8 to initiate the arcuate road movement represented by arrow A (FIG. 1).

The measuring chamber 24 is used only for measuring the fluid,
It is important to note that no physical or chemical changes occur while the fluid is enclosed in the chamber. In order to obtain steady power, the fluid has the same volume for each cycle,
It is preferable to supply at the same temperature and the same pressure. The fluid cannot be accurately metered during a chemical or physical reaction, so that when it leaves the metering chamber 24, it has the same chemical composition as it enters the metering chamber. Is preferred.

Referring now to FIG. 3A, which corresponds to the first position in the preferred embodiment shown, fluid is free to enter the metering chamber 24 in this position. When the pivot link arm 68 moves in the arc (FIG. 1) drawn by the arrow A, the tongue 67 is moved.
Moves in the opposite arcuate direction. Thus, the former upward pressure exerted on the first rod 34 by the upper arm 62 is released and the spring 38 biases the first seat 30 of the first valve 16 to engage the inlet 20 of the metering chamber 24. Try to match.

At this point, the spring biased valves 16, 18 are both closed to prevent fluid from entering and exiting the metering chamber 24 from the fluid supply can 28. This point is depicted in FIG. 3B and corresponds to the second position of actuation assembly 60. The metering chamber 24 is closed at both the inlet 20 and the outlet 22 and encloses the fluid therein to provide a metering volume of fluid within the chamber.

The loose engagement between tongue 69 and notch 67 described above is momentary in opening the second valve while pivot link arm 68 continues the arcuate movement indicated by arrow A (FIG. 1). Cause a delay. Due to the loose engagement, the pivot link arm 68
Moves, the upward displacement that opens the first valve 16 is released,
The control arm 66 is then delayed by not moving enough to open the second valve 18. This delay is due to the weighing room 24
It ensures that the fuel volume inside is kept constant, that no unnecessary additional amount enters the chamber and no premature leakage from the outlet 22 into the lower chamber 56 occurs.

The third position of actuation assembly 60 is shown in FIG. 3C, which is reached after first valve 16 is fully closed and second spring-loaded valve 18 is open. In this position, fluid is discharged from the metering chamber 24. In the preferred embodiment, the entire first valve sequence occurs when the actuator arm 60 moves continuously from the first position through the second position to the third position.

Following ignition of the tool 12, a second valve sequence is initiated where lifting of the tool from the workpiece causes the pivot link arm 68 to move the actuation assembly 60 to a third position. Move from the position through the second position to the first position. This sequence closes the outlet 22 of the metering chamber 24 from the downward flow and reopens the inlet 20 to allow the fluid to flow into the metering chamber 2.
Allow 4 to flow. Any stimulus that follows ignition of the tool 12 but precedes the first valve sequence is used to initiate this sequence.

The second valve sequence moves the first and second spring biased valves through the same steps as the first valve sequence, but in the reverse order. Starting from the third position of the actuation assembly 60 shown in FIG. 3C, the second spring biased valve 18 moves away from the outlet 22 to prevent fluid flow from the metering chamber 24. After the second valve 18 is completely closed, the second position of the actuation assembly 60 shown in FIG. 3B is obtained. Here, both valves 16 and 18 are closed to prevent backflow of the fluid, and the metering chamber 24 contains only the remaining amount of the fluid. Finally, the first spring biased valve 16 separates from the inlet 20 to allow free flow of fluid from the fluid source 28 to the metering chamber 24, but the fluid from the pressurized fluid source 28 to the inlet 20 and outlet of the metering chamber 24. 22 to prevent free flow to the combustion chamber passage 70.

In the preferred embodiment, this actuation or valve sequence is such that the upper arm 62 has the maximum clearance from the housing 12 (FIG. 3A) and the lower arm 64 has the maximum clearance from the housing 12 (FIG. 3A). 3C) is controlled by pivoting the link arm 68 which moves the actuation assembly 60 to 3C). In the preferred embodiment, notch 67
In addition to the loose mating engagement between the tongue 69 and the tongue 69, the actuation assembly 60 also provides a delay mechanism that operates between the closing action of one of the valves 16,18 to the closing action of the other valve 18,16. Have Any delay mechanism is suitable, such as electrical delay, electronic means of mechanical delay mechanism. In the most preferred mechanical delay mechanism, actuation assembly 60 is slidably coupled to each of rods 34,36. First rod 34
Is the first, such as a C-clip attached to the rod 34
Opener 71 and the second rod 36 has a second opener 72. The clearance of the openers 71, 72 on the rods 34, 36 is preferably used to delay the closing movement of one valve 16, 18 before the opening of the other valve 18, 16 occurs.

In the preferred delay mechanism, actuation assembly 60
Control arm 66 is longer than the housing 26 containing the valve assembly. The excess length causes the upper arm 62 and the lower arm 64 to sandwich the housing 12 in a sandwich fashion, leaving an excess gap between the housing and the actuator arms 62,64. In response to the stimulus that triggers the valve sequence, the control arm 66 moves up and down (tool related direction, shown in FIG. 3).

Referring now to FIG. 3A, actuation assembly 60
Moving the first valve sequence causes upper arm 62 to move to the first
To start contacting the opening tool 71. When the control arm 66 moves downward, the release or extension of the first spring 38 relative to the upper arm 62 until the first seat 30 contacts the metering chamber inlet 20 and closes the first spring biased valve. The first opening tool 71 is held. The control arm 66 moves sufficiently so that the upper arm 62
The first spring 38 urges the valve 16 to the closed position when is away from the first release tool 71 (as shown in FIG. 3B).
During movement of the control arm 66 from the first position (FIG. 3A) to the second position (FIG. 3B), the lower arm 64 slides along the second rod 36 and partially, not all, of the second spring 40. Compress. Then, during movement of the control arm 66 from the second position (FIG. 3B) to the third position (FIG. 3C), the lower arm 64
Slides along the second rod 36 and finally contacts the second opening 72 to compress the second spring 40 and open the second spring biasing valve 18. The second valve sequence similarly goes back through the above steps to close the second spring-loaded valve 18 and
A delay is introduced between the opening of the spring-biased valve 16 of

Seals are used where appropriate to prevent fluid flow to the valve assembly 10, metering chamber 24, and outer regions of the housing 12. The exact number, shape and location of such seals will depend on the valve assembly 10 for a particular application.
Depends on the exact shape of. In the disclosed preferred embodiment, a rod extends through the housing 26 to provide an actuation assembly 60.
Removable inserts 74 are optionally used to surround the rods 34, 36 of each spring-loaded valve 16, 18 as they come into contact with. An O-ring 76, gasket or similar device is preferably used to prevent leakage between the removable insert 74 and the housing 12 or the rods 34,36. In some uses, the length of the springs 38, 40 may be such that the upper chamber 54 or the lower chamber 5
It is preferred that it exceeds 6 dimensions. When this is preferred, the hollow chamber 7 is dimensioned to receive a portion of the length of the springs 38, 40 and the locking end 42.
4 has a removable insert 74. The removable insert 74 also provides for easy access to the spring biased valves 16, 18 and their components when replacement parts are installed.

Referring now to FIG. 4, this valve assembly 10
Is preferably provided with a mechanism for facilitating the movement or discharge of fuel from the metering chamber 24 through the outlet 22 and finally into the combustion chamber introducing passage 70. As mentioned above, it has been found that when this type of combustion-powered tool is operated at low temperatures, such as below 0 ° C, the fuel pressure drops and it becomes more difficult to transfer fuel to the combustion chamber. Has been issued. To address this issue, this valve assembly 10
Preferably comprises a disc 80 mounted on the valve 18, in particular on the end of a rod 36 arranged in the metering chamber 24. The disk 80 is preferably located closer to the inlet 20 when the valve 18 is closed. To this end, the disc 80 is mounted on a pedestal 82, which in turn is fixed to the conical seat 32. In the preferred embodiment, the disk 80 is made of brass or an equivalent rigid refractory material, and the pedestal 82 is made of rubber or similar flexible polymer or plastic material. However, other materials are also contemplated. Preferably, a friction fit connection between the pedestal lug 84 and the disc axial hole 86 frictionally joins the disc 80 to the pedestal 82. However, pedestal 8 disk 80
Other methods of fastening to No. 2 are also contemplated, including but not limited to ultrasonic welding, insert molding, gluing or other mechanical fasteners. The disk 80 is dimensioned to have a diameter that is approximately equal to, but less than, the diameter of the metering chamber 24.

In operation, when valve 18 is opened as described above in connection with FIG. 3C, disk 80, along with seat 32, moves from a rest position near the inlet of metering chamber 24 to a position closer to outlet 22 (see FIG. 4). (Best shown).
This movement pushes any remaining fuel from the metering chamber 24 through the outlet 22 and finally into the combustion chamber conduit 70.
In this way, the fuel is mechanically removed from the metering chamber 24. However, since the problem of low fuel pressure is related to temperature, there is an alternative approach to providing an auxiliary exhaust passage 88 through which hot exhaust from the combustion chamber warms the metering chamber during tool operation. An equivalent arrangement may be to provide an electrical heating element energized by resistance, or other known device for maintaining sufficient temperature in the metering chamber 24 to maintain fuel pressure.

Referring now to FIG. 5, valve 10 and fuel can 2
The connection with 8 is shown in detail. The important thing is valve 1
A sealing relationship is established between 0 and the fuel can 28 to prevent loss of fuel as well as to prevent unwanted combustion.
Fuel can 28 includes an internal stem 90 that forms an outlet for the fuel contained in the can under pressure, as is known in the art. Stem 90 is secured to and surrounded by end cap 92, which is known in the art and illustrated in US Pat. No. 5,115,944 incorporated herein by reference, which is surrounded by end cap 92. The end of the can is covered and a rolling seam 94 is formed on it.

An adapter 96 frictionally engages the end cap 92 and surrounds and protects the protruding stem 90. Axial passage 98 is formed by adapter 96 and receives stem 90. In the preferred embodiment, the adapter also has a frangible end membrane 100 that closes the passage 98 to provide a visual indication of whether the can 28 has been used. Membrane 100 is configured to be pierced when in mating engagement with nipple 51. Therefore, the passage 98 is sized to receive the nipple 51.

Similarly, the nipple 51 is preferably substantially cylindrical in shape and has a diameter or cross-sectional parameter dimensioned to slide-fit into the passageway 98 and the can 28 and valve 10. It has a length dimensioned to provide fluid communication there between. In the preferred embodiment, the nipple 51 is cylindrical, but other non-circular cross-sectional shapes including oval, square, rectangular and polygonal shapes are also contemplated by the application.

In the preferred embodiment, the nipple 51 and stem 90 are shaped so as to form a sealing relationship during operational engagement as shown in FIG. This relationship, which is designed to prevent unnecessary loss of fuel, is
Achieved by frictional contact between the zero end 102 and the end 104 of the nipple 51. However, it is preferred that some form of sealing is provided on at least one of the nipple 51 and the stem 90. In the preferred embodiment, the seal formation is a resilient O-ring 1 provided on the nipple 51.
It is 06. However, other types of known sealing formations are contemplated including, but not limited to, annular seals, molded seals and flat washers.

The nipple end 104 also defines a chamber 108 for receiving or catching an elastic seal member such as an O-ring 106. In particular, the end 104 is tapered or chamfered for the dual purpose of holding the O-ring 106 and facilitating insertion of the nipple 51 into the adapter passage 98. Tapered end 104 is easier, but preferably nipple 5,
Especially when 1 is made of a metal such as brass, the membrane 10
However, other suitable rigid and service life materials are contemplated.

To further improve the sealing relationship between the engaged nipple 51 and stem 90, the stem end 102 is
It is shaped to fit and engage or house the O-ring 106. Therefore, the end 102 has an annular groove 110.
Are preferably provided. Of course, an O-ring 106 or other resilient seal member may alternatively be used in the stem 90.
It is contemplated that the nipple end 104 be attached to the nipple end 104 by adhesive attachment in a groove (not shown), or other type of O-ring attachment technique known in the art.

When the fluid flow with the can 28 is necessary for some reason depending on the place of use, the other end of the end 104 is connected in the form of a nipple 51 which is in fluid communication with a desired fluid can or container. Tools are provided.

In use, the can 28 is inserted into the combustion tool and the nipple 51 fits and engages the adapter 96. The can 28 is pressed against the nipple 51 and the membrane 1
00, a nipple end 104 enters the passage 98,
Finally, the stem end 102 is contacted. As mentioned above,
Once the sealing relationship has been successfully obtained, it is contemplated that other locking devices may be used to secure the can 28 in this position.

It will be appreciated by those skilled in the art that this valve assembly and metering transformer provide a simple way to deliver a constant volume of fluid to the power fastening tool. 2 spring-loaded valves 1
6, 18 control the inflow and outflow to the constant volume metering chamber 24 to meter a fixed amount of fluid regardless of variations in fluid flow rate. The actuation assembly 60 controls the opening and closing of valves 16 and 18,
It receives fluid from the pressure source 28 and meters it before flowing to the combustion or expansion chamber. This arrangement of valves 16, 18 minimizes seal wear and reduces maintenance work.

Referring now to FIG. 6, an alternative embodiment of this valve assembly is shown generally at 120. Common parts of assembly 10 and assembly 120 are designated by the same reference numerals. The main difference between assembly 10 and assembly 120 is that valve assembly 120 allows the user to selectively adjust the amount of fuel delivered by the valve assembly to the combustion chamber of the tool.
However, it has a mechanism for changing the capacity of the fuel measuring chamber 24. This adjustability is particularly useful when the tool is used at high altitudes where the air is lean and low fuel is required for efficient combustion.

In the preferred embodiment, the mechanism for varying the volume of the fuel metering chamber is a capacity adjusting plunger 122, referred to herein as a plunger, which is adapted to reciprocate linearly with respect to the metering chamber 24. An elongated member oriented in the direction. The plunger preferably reciprocates in the direction of its longitudinal axis substantially perpendicular to the operating axis formed by the valves 16,18.

The plunger 122 is considered to have a shape that will withstand the operating environment of the combustion tool and otherwise take up the space within the metering chamber 24 occupied by the fuel. In the preferred embodiment, the plunger 122
Is an elongated metal shaft or rod having a valve end 124 and an adjusting end 126. As mentioned above, the valve end 124 causes the metering chamber 24 to take up a predetermined amount of space otherwise occupied by fuel before each ignition cycle of the tool.
Is configured to reduce the volume of the. As described herein, the valve end 124 is generally cylindrical with a truncated end, but the end may alternatively have a shape complementary to the wall 128 of the metering chamber 24. It is considered.

On the opposite side of the valve end 124, an adjusting end 126
Is shaped for selective operation, here the axial rotation performed by the screwdriver groove 130 in the preferred embodiment. Any conventional shaped driver groove is considered suitable, including but not limited to grooved Phillips, Trux and Allen hex wrenches or conventional sockets. Custom-made configurations are also contemplated when only certain qualified maintenance personnel are allowed to adjust the tool.

Valve end 1 entering and leaving the measuring chamber 24
Plunger 122 is preferably threaded between valve end 124 and adjusting end 126 so that the axial reciprocation of 24 is positively controlled. Any equivalent structure to achieve this end is also envisioned. Also, the plunger 122 is of sufficient length to allow adjustment outside the valve housing 12.

The sleeve 132 is shaped to be operatively supported with respect to the valve housing 12 and reciprocally receives the plunger 122. More particularly, the sleeve 132 surrounds and supports the plunger 122 and is secured to the housing 12, preferably by press fit within the hole 134. The hole 134 communicates with the measuring chamber 24. Other methods of securing the sleeve 132 to the housing 12 are also contemplated, including welding, chemical gluing, and the like. The sleeve 132 has a through hole 136 at the center.
Which is in communication with the metering chamber 24 and is sized to receive the plunger 122. The sleeve 132 is of sufficient length and extends generally perpendicular to the valve housing 12 for proper support of the plunger 122. However, the plunger 122 has a sleeve 13
It is preferably longer than 2. Outer end 138 of sleeve 132
Are preferably threaded to mate with threads 140 of plunger 122. Plunger 122 and sleeve 1
The detailed position of the corresponding threaded portion of 32 can be changed according to the intended use.

Since the hole 134 and the through hole 136 communicate with the measuring chamber 24, it is important that they are sealed to prevent unnecessary leakage of fuel. Accordingly, the sleeve 132 preferably comprises a seal 142 in the form of an O-ring located within an appropriately sized O-ring groove 144. Depending on the condition of use, the groove 144 is formed in the sleeve 132.
Alternatively, it is provided in either one of the holes 134. In addition, the plunger seal 146, which is also preferably an O-ring,
Seals through hole 136 and is placed in groove 148 in either through hole 136 or plunger 122.

Plunger 122 is preferably located in the metering chamber in a biased position so that the operation of valves 16 and 18 is not compromised. In other words, the plunger 12
The longitudinal axis of 2 is the measuring chamber 24 in the reciprocating direction of the plunger.
Is offset from the vertical plane that bisects. Practically speaking, and now referring to FIG. 6, the plunger 12
2 is behind the axis of movement of the valves 16,18.

Referring now to FIG. 7, another feature of the device 120 is that the plunger 122 or the plunger 122 or the fuel pressure can be used at relatively low temperatures (below 0 ° C.) as described above. That is, the sleeve 132 is heated.
Heat is supplied electrically by connecting to an input line 150 which is powered by the tool's storage battery (not shown).

Alternatively, the plunger 122 can be switched to the static heating element 152 for heating. The heating element 152 can be reciprocated within the sleeve 132 with a friction fit, and it is also contemplated to connect to a storage battery as is known in the art. Auxiliary exhaust passage 88 (Fig. 4)
Additional heat may be provided from the combustion chamber, as described above in connection with.

While particular embodiments of the constant volume valve assembly and metering chamber have been shown and described, changes and modifications can be made without departing from the invention in its broader aspects and the invention defined in the following claims. Those of ordinary skill in the art will understand what can be done.

[Brief description of drawings]

FIG. 1 is a rear view of the present constant volume valve assembly attached to a fuel can.

FIG. 2 is a front sectional view of the present constant volume valve assembly.

3A-3C are a series of partial cross-sectional views of the present constant volume valve assembly showing three valve positions as the actuation assembly moves through an actuation sequence.

FIG. 4 is a partial cross-sectional view of the present constant volume valve assembly shown with a disc that facilitates transfer of fuel from the metering chamber to the combustion chamber.

FIG. 5 is a partial cross-sectional view of an alternative embodiment of the present constant volume valve assembly showing the sealing connection between the valve and the internal nozzle of the pressurized fuel cartridge.

6 is a partial cross-sectional view taken along line 6-6 of FIG. 4, viewed in the direction shown schematically and showing an alternative embodiment of the present valve assembly.

FIG. 7: The metering axis is replaced by a heating element, FIG.
7 is an alternative embodiment of the valve assembly shown in FIG.

[Explanation of symbols]

10 ... Valve assembly 12 ... Housing 16, 18 ... Spring biased valve 20 ... Entrance 22 ... Exit 24 ... Weighing room

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tony Diso             60083, Illinois, United States of America             Zworth, Stonegate Road             13961 (72) Inventor Walter Jay. Tailor             United States, Illinois 60050, Mc             Henry, North Green Street               1501 F-term (reference) 3C068 BB01 CC03 DD03

Claims (11)

[Claims] 1. A valve assembly with a metering chamber for use with a fluid containing pressurized fluid source in a combustion powered tool, the valve assembly comprising a plurality of inlets and outlets. A housing forming a metering chamber having a port, a first spring-loaded valve disposed in the housing for controlling fluid flow through the inlet, and disposed in the housing through the outlet. A second spring-biased valve that controls the flow of fluid; and a first spring-biased valve that is connected to the first and second spring-biased valves and is open and that has the second spring-biased valve. A second position in which the first and second spring-biased valves are both closed, a third position in which the first spring-biased valve is closed and a second spring-biased valve is open; An actuating assembly continuously operable to a position, the first position The volume of fluid entering the chamber from the inlet at the position is collected in the metering chamber, sealed at the second position, and discharged from the metering chamber at the third position to the first position. A valve assembly configured and arranged to deliver a metered amount of fluid with each successive movement of the actuating body from the to the third position. 2. The actuating assembly includes the first and second spring bias valves from the third position where the first spring bias valve is closed and the second spring bias valve is open. Can be operated to the second position in which both are closed, the first spring-biased valve is opened and the second spring-biased valve is closed, and the fluid amount is in the third position. After being discharged from the metering chamber and being supplied with a constant volume of fluid, the metering chamber is sealed to prevent backflow of the fluid at the second position;
2. The valve assembly of claim 1, wherein the metering chamber is refilled with fluid volume at the first position with each successive movement of the actuating body from the first position to the first position. 3. The metering chamber has a volume of collected fluid,
The valve assembly of claim 1, wherein the valve assembly is constructed and arranged to equal the volume of fluid expelled from the metering chamber. 4. The valve assembly of claim 1, wherein the metering chamber comprises a device that facilitates draining of fuel from the chamber. 5. A delay occurs between the closing of one of the first or second spring-biased valves and the opening of the other of the first or second spring-biased valves. The valve assembly of claim 1, further comprising a delay mechanism configured to cause 6. The first and second spring biased valves each have a biasing rod, and the actuation assembly is slidably coupled to the rods between the housing and an opening. The delay is caused by slidable movement of the actuation assembly between the opening of one of the spring-loaded valves and the opening of the other valve of the spring-loaded valve. 6. The valve assembly of claim 5, wherein the opener is disposed on the rod. 7. The actuating assembly includes a control arm configured to actuate the first and second spring biased valves and to engage the control arm to effect the actuation. 7. A valve assembly according to claim 6, further comprising a pivot link arm configured, said arm being configured to have a loose mating engagement to generate said delay. 8. The valve assembly of claim 1, further comprising means for adjusting the internal volume of the metering chamber. 9. The valve assembly according to claim 8, wherein said adjusting means comprises a plunger configured for adjustable reciprocating movement with respect to said metering chamber. 10. The valve assembly of claim 1, further comprising a heater provided in operative relationship with the housing to heat the metering chamber. 11. A variable volume metering chamber for use with a combustion power tool comprising a housing having an internal volume forming a metering chamber including an inlet and an outlet, and means for adjusting the internal volume of the metering chamber. With valve assembly.