Combustion-engined tool having a combustion chamber with a...

Internal-combustion engines – Precombustion and main combustion chambers in series – Valveless precombustion chamber

Reexamination Certificate

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

C123S465000

Reexamination Certificate

active

06443118

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a portable, combustion-engined tool and, in particular, a setting tool having a combustion chamber for receiving a fuel gas, and an ignition device for igniting the fuel gas for building up pressure in the combustion chamber for driving a setting piston adjoining the combustion chamber.
2. Description of the Prior Art
The drive energy in the tool described above is obtained by combustion of a fuel gas mixture, e.g., an air-fuel gas mixture, in the tool combustion chamber, and is transmitted to a fastening element, which need be driven in an object, via the piston.
The combustion-engined tool can have only one combustion chamber. However, a combustion-engined tool can have a combustion chamber that is divided in several chamber sections. In each case, the fuel gas mixture can be present in the chamber sections in different mixture ratios. For the sake of clarity, a combustion chamber would be considered which is divided only into chamber sections, a forechamber section and a main chamber section.
The combustion starts in the forechamber section by an electrical spark generated by the ignition device. Upon ignition of the mixture, a flame front starts to propagate radially with a relatively small velocity. The flame front pushes the unconsumed air-fuel gas mixture ahead of itself, and the unconsumed air-fuel gas mixture penetrates through the through-openings in the separation plate into the main combustion chamber section, creating there turbulence and pre-compression.
As the flame front reaches the through-openings, flame penetrates therethrough, due to the small cross-section of the openings, in a form of flame jets into the main chamber section, creating there a further turbulence. The thoroughly intermixed air-fuel gas mixture in the main chamber section ignites over the entire surface of the flame jets. The mixture burns with a high speed which substantially increases the effect of combustion as the losses which are caused by cooling, remain small.
A combustion chamber, which is divided in several chamber sections, can be formed as a collapsible combustion chamber having limiting opposite walls movable relative to each other.
An object of the present invention is a combustion-engined tool of a type discussed above having an increased capability of adjusting the energy transmitted to the piston.
SUMMARY OF THE INVENTION
This and other objects of the present invention, which will become apparent hereinafter, are achieved by providing a gas drain arrangement that permits to control pressure build-up in the combustion chamber by draining a controlled amount of the fuel gas mixture. The fuel gas mixture can be drained through one or more drain channel(s) formed in the bottom region of the combustion chamber or in the main chamber section. By controlling the amount of the fuel gas mixture in the combustion chamber, an energy transmitted to the piston can be directly controlled.
In accordance with one embodiment of the present invention, the gas drain arrangement has a drain channel with an adjustable cross-section. For controlling the channel cross-section, an adjustable throttle or an adjusting screw with a radial through-channel can be used. In both cases, the channel cross-section can be changed to drain a controlled amount of the gas upon pressure build-up in the combustion (main) chamber.
According to an advantageous embodiment of the present invention, the gas drain arrangement includes a check valve for closing the combustion chamber when an underpressure prevails therein. The return of the piston into its initial position, after the attachment element has be drived in, is effected as a result of thermal feedback, i.e., during a phase when underpressure prevails in the combustion chamber or the main chamber section. The piston is displaced into its initial position until it engages a stop. To maintain the underpressure in the combustion chamber, it should remain closed during the return movement of the piston. This function is performed by the check valve.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiments, when read with reference to the accompanying drawings.


REFERENCES:
patent: 3638632 (1972-02-01), Boling
patent: 4773581 (1988-09-01), Ohtsu et al.

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Combustion-engined tool having a combustion chamber with a... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Combustion-engined tool having a combustion chamber with a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Combustion-engined tool having a combustion chamber with a... will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-2886355

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.