AU2004316402B2 - Shock-absorbing system for fastener driving tools - Google Patents
Shock-absorbing system for fastener driving toolsInfo
- Publication number
- AU2004316402B2 AU2004316402B2 AU2004316402A AU2004316402A AU2004316402B2 AU 2004316402 B2 AU2004316402 B2 AU 2004316402B2 AU 2004316402 A AU2004316402 A AU 2004316402A AU 2004316402 A AU2004316402 A AU 2004316402A AU 2004316402 B2 AU2004316402 B2 AU 2004316402B2
- Authority
- AU
- Australia
- Prior art keywords
- assembly
- shock
- cylinder body
- probe assembly
- probe
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Ceased
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Description
SHOCK-ABSORBING SYSTEM FOR FASTENER DRIVING TOOLS
BACKGROUND OF THE INVENTION The present invention relates to improvements in combustion tools, such as
the type used for driving fasteners into work pieces. More specifically, the present
invention relates to high-powered combustion tools. A suitable combustion-powered tool assembly is described in commonly
assigned patents to ikolich U.S. Patent No. 5,197,646, and U.S. Pat. Nos. 32,452, 4,552,162,
4,483,473, 4,483,474, 4,403,722, and 5,263,439, which are incorporated by reference. Such
fastener-driving tools are available commercially from ITW-Paslode (a division of Illinois
Tool Works, Inc.) of Vernon Hills, Illinois, under its IMPULSE trademark. Such tools incorporate a generally pistol-shaped tool housing enclosing a small
internal combustion engine. The engine is powered by a canister of pressurized fuel gas,
also called a fuel cell. A powerful, battery-powered electronic power distribution unit
produces the spark for ignition, and a fan located in the combustion chamber provides for
both an efficient combustion within the chamber, and facilitates scavenging, including the
exhaust of combustion by-products. The engine includes a reciprocating piston with an
elongate, rigid driver blade disposed within a cylinder body.
A valve sleeve is axially reciprocable about the cylinder and, through a probe
assembly linkage, moves to close the combustion chamber when a work contact element at
the end of the probe assembly is pressed against a workpiece. This pressing action also
triggers a fuel metering valve to introduce a specified volume of fuel into the closed combustion chamber.
Upon the pulling of a trigger switch, which causes the ignition of a charge of
gas in the combustion chamber of the engine, the piston and driver blade are shot downward
to impact a positioned fastener and drive it into the workpiece. The piston then returns to its
original, or "ready" position through differential gas pressures within the cylinder. Fasteners
are fed magazine-style into the nosepiece, where they are held in a properly positioned
orientation for receiving the impact of the driver blade.
There is a general interest by designers of such combustion tools to increase
combustion efficiency. This has resulted in tools with greater power, generated by a more
powerful combustion event in the combustion chamber. One disadvantage of conventional
combustion tool assemblies is that, as the tool is operated, significant loads are applied to
the workpiece contacting element and transmitted throughout the tool assembly. In
particular, as the piston and attached driver blade drive the fastener and reach the bottom of
the piston stroke, significant impact forces are generated. These forces are transmitted
through the cylinder to the movable valve sleeve, which is connected through a linkage to
the workpiece contact element also referred to as the probe assembly. Impact forces are
particularly felt at contact points between the cylinder and the valve sleeve/probe
assembly. As such, as combustion tools increase in power, the higher loads can lead to
breakage of the various parts of the tool, especially the above-discussed contact points
between the probe assembly and lower portion of the valve sleeve. Tests have shown that
during operation of a typical combustion tool, the piston speed tops about ninety miles per
hour is reduced to zero miles per hour at impact. Such repeated impacts have in some
cases reduced tool operation life due to premature breakage of components.
Another disadvantage of conventional combustion tool assemblies with
higher-powered combustion is that a high driving velocity of the piston can also lead to a
higher return velocity of the piston after driving the fastener into the workpiece. The shock
from abruptly stopping the piston at the top of the cylinder, as the upper probe assembly
contacts the stop tabs on the cylinder or valve sleeve, can cause the piston to bounce back
down the cylinder away from the proper firing position. A movement away from the
proper firing position can unintentionally increase the volume of the combustion chamber
and lead to misfires of the tool.
Still another factor in the use of combustion tools is that there is constantly a
need for lighter and smaller tools. Nikolich U.S. Patent No. 5,197,646, listed above,
describes a suitable assembly for shortening the overall length of a combustion-powered
tool; however, there is a need for continual improvement in the overall weight of the tool.
Accordingly, there is a need for an improved combustion-powered tool
design that reduces the load forces transmitted to the valve sleeve and probe assembly. In
addition, there is a need for an improved combustion-powered tool that is less susceptible
to a component failure through combustion-generated impact forces.
BRIEF SUMMARY OF THE INVENTION The above-listed needs are met or exceeded by the present shock- absorbing
system for a fastener tool. A main feature of the present system is that the point of contact
between the valve sleeve/probe assembly and the cylinder body has been moved away
from the conventional location at the lower portion of the cylinder body to an upper part of
the cylinder body. Additionally, the system includes a shock-absorbing member for
dampening the impact forces and shock transferred from the probe assembly to the
cylinder body. The shock-absorbing element is preferably located between upper ends of
the arms of the probe assembly and a tab from the cylinder body to reduce the stress on the
tool members as the probe assembly returns from the fastener-driving position. It has been
found that the current application results in a seven-fold reduction on impact forces
generated through combustion. Another feature of the present system is that a pair of valve
sleeve return springs used in conventional combustion tools of this type has been replaced
by a single spring generally centrally located on an upper probe of the probe assembly. More specifically, A combustion chamber assembly for use in a combustion-
powered fastener driving tool, includes a cylinder body, a reciprocating probe assembly
slidably mounted to said cylinder body between a first, extended position and a second,
retracted position, and at least one shock-absorbing member operationally associated with
at least one of the cylinder body and the probe assembly for reducing shock load generated
during operation of the tool. In another embodiment, a single spring disposed between the
probe assembly and the cylinder body is configured for biasing the probe assembly into the
first position.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 is a perspective view of a combustion chamber assembly suitable for
use with the present shock- absorbing system in a combustion powered tool, with parts
omitted for clarity;
FIG. 2 is a fragmentary perspective view of the present shock-absorbing
system with the valve sleeve in the closed position and tool in the rest position; and
FIG. 3 is a fragmentary perspective view of the relative disposition and
connection of the components of the present shock-absorbing system with the valve sleeve
in the closed position and tool in the rest position.
DETAILED DESCRIPTION OF THE INVENTION RefenĪng now to FIG. 1, a combustion chamber assembly incorporating the
features of the present shock-absorbing system is generally designated 10 and is intended
for use in a combustion-powered tool, especially the type used for driving fasteners. A
combustion-powered tool of the type suitable for incorporating the present system is
described in detail in the patents incorporated by reference and referred to above. As is
known in the art, the combustion chamber assembly 10 includes a valve sleeve 12 which is
preferably generally cylindrical in shape. Included on the valve sleeve 12 are a lower end
14 and an upper end 16. As is known in the combustion-tool art, the valve sleeve 12 is
slidably engaged upon a generally cylindrical cylinder body 18. An upper end 20 of the
cylinder body 18 generally corresponds to the upper end 16 of the valve sleeve 12, and a
lower cylinder body end 22 extends below the lower end 14 of the valve sleeve 12. The
cylinder body 12 defines a longitudinal tool axis. In the context of this specification, the
terms "upper", "lower" and "vertical" refer to the orientation of the combustion chamber
assembly 10 as depicted in FIG. 1, however it is contemplated that the assembly may be
operated in many varied orientations.
The upper end 16 of the valve sleeve 12 and the upper end 20 of the cylinder
body 12 partially define a combustion chamber 24. A piston (not shown) is mounted
operatively in the cylinder body 12, and is constructed and arranged for driving a driving
blade (not shown) in the longitudinal direction thereby driving a fastener (not shown).
A reciprocating probe assembly 26 is slidably mounted along the cylinder
body 12 and is configured for contacting a workpiece (not shown) and subsequently
closing the combustion chamber 24 by moving the valve sleeve 12 between a first,
extended or rest position (FIG. 2) and a second or retracted position (FIG. 3). In the
former, the combustion chamber 24 is open, and in the latter, the chamber is closed prior to
combustion.
Included in the probe assembly 26 is a workpiece contact element 28 with a
first end 30 configured for engaging the workpiece and a second end 32 connected to a
depth of drive mechanism 34 which adjusts the position of the workpiece contact element
28 relative to a fixed nosepiece 36 as is known in the art. The depth of drive mechanism
34 is associated with an intermediate element 38 of an upper probe 40 which includes the
intermediate element and a pair of arms 42 extending vertically from the intermediate
element generally parallel to the longitudinal axis of the cylinder body 18. Each arm 42 is
associated with a corresponding side of the cylinder body 18.
In the preferred embodiment, at upper ends 44 of each of the arms 42, an
angled seat or lip 46 is formed by bending the end laterally, preferably at an approximate
right angle. The amount of inclination may vary to suit the application. The seat 46 also
engages a link pin 48 which connects each of the arms 42 to a corresponding part of the
lower end 14 of the valve sleeve 12. Thus, the valve sleeve 12 moves relative to the
cylinder body 18 with the probe assembly 26 generally parallel to the longitudinal axis of
the cylinder body.
Referring now to FIGs. 2 and 3, an exterior of the cylinder body 18 is
provided with a plurality of cooling fins 50 which in the preferred embodiment are
integrally formed with the cylinder head. However, other fastening techniques are
contemplated. A pair of adjacent fins 52 on each side of the cylinder body 18 defines a
track 54 which generally parallels the longitudinal axis of the cylinder body. It will be
seen that the angled seat 46 reciprocates in the track 54 as the probe assembly 26 moves
relative to the cylinder body 18.
An important feature of the present combustion assembly 10 is that at least
one shock-absorbing element 56 is located between the cylinder body 18 and an upper
portion of probe assembly 26, preferably the angled seat 46. In the preferred embodiment,
the at least one shock-absorbing element 56 is generally cylindrical in shape, however
other shapes are contemplated depending on the application. Further, the shock-absorbing
element 56 is configured to generally complement the track 54. In the preferred
embodiment this means a generally cylindrical element is engaged in a generally concave
track, however other shapes are contemplated, including tongue-in-groove construction.
It is also preferred that the shock-absorbing member 56 is freely slidable in
the track 54. However, it is also contemplated that the member 56 may be secured as by
adhesive, Vulcanization, or other similar technology to the angled lip 46. Either way, the
shock-absorbing member 56 is configured for common travel with the probe assembly 26 in the track 54.
An upper end of the track 54 is defined by an element of the cylinder body
18 referred to as a tab 58, preferably integrally formed with the cylinder body 18, or
attached by suitable techniques such as adhesive, welding, etc. The position of the tab 58
in the track 54 and relative to the angled seat 46 may vary to suit the application.
Each of the preferably two shock-absorbing members 56 (one associated
with each of the arms 42) is configured for reducing load forces generated in the
combustion chamber 24 upon the probe assembly 26 reaching the second position (FIG. 3),
and is configured to have sufficient rigidity to limit the travel of the probe assembly 26
relative to the cylinder body 18 and to also have sufficient resilience for absorbing shock
forces generated by the tool in the second position, once combustion occurs. The shock-
absorbing member 56 is preferably made of a resilient rubber-like material, and it is
contemplated that the Shore hardness of the material may vary to suit the application, such
as the power level of the tool in which the combustion chamber assembly 10 is mounted. As is seen in FIG. 3, in the retracted or closed combustion chamber position,
the shock-absorbing member 56 prevents further upward travel of the arm 42 toward the
tab 58, but has sufficient residual resiliency for absorbing combustion-induced shock loads
transmitted by the arms 42 to the cylinder body 18 through the tabs 58. In prior art
combustion tools, it was known for such loads to cause premature failure of tool
components.
In the present assembly, it is also contemplated for the shock-absorbing
member 56 to be secured to an underside 60 of the tab 58. On an upper side 62 of the tab
58, a resilient stop block 64 is preferably affixed. The purpose of the stop block 64 is to
dampen shock loads generated by the impact of a shoulder 66 of the valve sleeve 12
impacting the tab 58 when the combustion chamber assembly 10 moves from the retracted
position of FIG. 3 to the extended position of FIG. 2. It is also contemplated that the stop
block 64 is made of the same resilient material as the shock-absorbing member 56, and
even that the two are connected to each other (seen in phantom in FIG. 3). Also, multiple
shock-absorbing members 56 are contemplated in each track 54. For example, a first
member 56 associated with the angled seat 46 and a second associated with the tab 58. Referring again to FIG. 1, the cylinder body 18 is preferably provided with a
retaining ring 70 associated with, and preferably fixed to the lower end 22 of the cylinder
body 18. The retaining ring 70 extends radially from the cylinder body 18. Also, the
retaining ring 70 provides a seat for a first end 72 of a spring 74. While conventional
combustion chamber assemblies employ two springs for returning, or biasing, the probe
assembly 26 to the extended position (FIG. 2), a feature of the present assembly 10 is that
the two springs, normally located where the shock-absorbing members 56 are disposed, are
eliminated and replaced by the single spring 74. In the preferred embodiment, the spring
74 is a conical spring, with the first end 72 being a relatively wider end mounted to the
retaining ring 70, and a second end 76 being relatively narrower or smaller diameter, and
being disposed against, or mounted to a stop 80 located on the intermediate element 38.
Preferably, the second end 76 is disposed against a portion of the depth of drive adjustment
mechanism 34.
It has been found that by replacing the springs with the shock-absorbing
member 56, and employing the single spring 74 as disclosed, the shock loading on the
lower end of the cylinder body 18 and the associated components is reduced approximately
sevenfold.
After the tool fires, high forces are applied through the probe assembly 26.
In the preferced embodiment, the probe assembly 26 is stopped and toe stress forces
dampened by the shock-absorbing member 56 acting in compression between the arms 42
and the associated tabs 58. However, it is contemplated that combustion chamber
assembly 10 can be configured to suit the application. It is conteirLplated that the
combustion chamber assembly 10 can be configured with a spring or elastic polymer
shock-absorbing member 56 that exerts a biasing force on the upper surface 62 and as such
pulls on the cylinder body tab 58 and the probe assembly 26 instead of compressing the
shock-absorbing member 56. It will thus be seen that the present combustion chamber assembly 10, with
the shock-absorbing system including the at least one shock-absorbing member 56 and the
single return spring 74 provides for a way to easily and cost-effectively move the impact
forces of the probe assembly 26 from a lower part of the tool to a more secure part of the
tool and dampen the stress forces at the point of contact. It has been found that the
implementation of the present system extends combustion tool operational life, especially
in tools having greater combustion power.
While particular embodiments of the present combustion chamber assembly
has been shown and described, it will be appreciated by those skilled in the art that changes
and modifications may be made thereto without departing from the invention in its broader
aspects and as set forth in the following claims.
Claims (19)
1. A combustion chamber assembly for use in a combustion-powered
fastener driving tool, comprising: a cylinder body; a reciprocating probe assembly slidably mounted to said cylinder body
between a first, extended position and a second, retracted position, said probe assembly
and configured for contacting a workpiece; and at least one shock-absorbing member operationally associated with at least
one of said cylinder body and probe assembly for reducing shock load generated during
operation of the tool.
2. The assembly of claim 1 wherein said probe assembly includes an
upper probe including at least one arm portion configured for sliding relationship relative
to said cylinder body, said at least one shock-absorbing element disposed between said at
least one arm and a corresponding element of said cylinder body for transmitting loads
from said probe assembly to said cylinder body.
3. The assembly of claim 2, wherein said upper probe includes a
substantially perpendicular lip at an upper end for contacting said at least one shock-
absorbing element.
4. The assembly of claim 2 wherein said cylinder body defines a track
for the slidable relative movement of said probe assembly, and said at least one shock-
absorbing member is configured for slidable movement in said track.
5. The assembly of claim 4 wherein said cylinder body includes at least
one tab for defining an upper limit of movement of said probe assembly.
6. The assembly of claim 5 wherein said at least one shock-absorbing
member is configured for common travel with said probe assembly to said tab.
7. The assembly of claim 6 wherein said at least one shock-absorbing
member is freely slidable in said track.
8. The assembly of claim 6 wherein said at least one shock-absorbing
member is secured to one of said probe assembly and said tab.
9. The assembly of claim 6 wherein said at least one shock-absorbing
member includes a first portion secured to said probe assembly and a second portion
secured to said tab.
10. The assembly of claim 7 wherein said at least one shock-absorbing
member is configured to be substantially complementary with said path.
11. The assembly of claim 1, wherein said at least one shock-absorbing
member is generally cylindrical in shape.
12. The assembly of claim 1, wherein said at least one shock-absorbing
member is configured for reducing load forces generated in a combustion chamber of said
assembly upon said probe assembly reaching said second position, and being configured to
have sufficient rigidity to limit the travel of said probe assembly relative to said cylinder
body and also sufficient resilience for absorbing shock forces generated by the tool in said
second position.
13. The assembly of claim 1 further including at least one spring between
said probe assembly and said cylinder body, configured for biasing said probe assembly
into the first position.
14. The assembly of claim 13, wherein said probe assembly is biased into
said first position by a single conical spring associated with said probe assembly.
15. The assembly of claim 13 further including a retaining ring, wherein
one end of said spring is seated on said retaining ring.
16. The combustion chamber assembly of claim 15, wherein a larger
diameter end of said spring is mounted to said retaining ring and a smaller diameter end of
said spring is mounted to said probe assembly.
17. A combustion chamber assembly for use in a combustion-powered
fastener driving tool, comprising: a cylinder body; a reciprocating probe assembly slidably mounted to said cylinder body
between a first, extended position and a second, retracted position; and a single spring disposed between said probe assembly and said cylinder body
and configured for biasing said probe assembly into the first position.
18. The assembly of claim 17, wherein said single spring is a conical
spring.
19. The assembly of claim 17, wherein a larger diameter end of said
spring is mounted to a retaining ring and a smaller diameter end of said spring is mounted
to said probe assembly.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/774,269 | 2004-02-06 | ||
US10/774,269 US6964362B2 (en) | 2004-02-06 | 2004-02-06 | Shock-absorbing system for fastener driving tools |
PCT/US2004/042297 WO2005082580A1 (en) | 2004-02-06 | 2004-12-16 | Shock-absorbing system for fastener driving tools |
Publications (2)
Publication Number | Publication Date |
---|---|
AU2004316402A1 AU2004316402A1 (en) | 2005-09-09 |
AU2004316402B2 true AU2004316402B2 (en) | 2007-05-03 |
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