Information
-
Patent Grant
-
6378288
-
Patent Number
6,378,288
-
Date Filed
Tuesday, February 13, 200123 years ago
-
Date Issued
Tuesday, April 30, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Sidley Austin Brown & Wood, LLP
-
CPC
-
US Classifications
Field of Search
US
- 060 396
- 060 597
- 123 46 R
- 123 46 S
- 123 46 C
- 123 46 H
- 123 590
- 123 593
- 123 306
- 123 309
- 123 262
- 123 263
-
International Classifications
-
Abstract
A combustion-engined tool including two opposite combustion chamber walls (14,18), and an ignition device (52) arranged between the two opposite combustion chamber walls for igniting a fuel gas mixture occupying space between the two walls, and an element located between the ignition device (52) and openings (38) formed in one of the two walls (18) for localized swirling a laminary expanding flame front formed upon ignition of the fuel gas mixture with the ignition device (52).
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a combustion-engined tool including two opposite combustion chamber walls, and an ignition device arranged between the two opposite combustion chamber walls for igniting a fuel gas mixture occupying space between the two walls, with one of the two walls having a plurality of openings spaced from the ignition device.
2. Description of the Prior Art
A setting tool for driving in of fastening elements can serve as an example of a tool described above. Such setting tool is disclosed in German Publication No. 199 50 351. The setting tool disclosed in this German Publication includes two, extending parallel to each other, combustion chamber walls and an ignition device arranged between the two walls for igniting a combustible fuel gas mixture filling the space between the two walls, such as air-fuel gas mixture, oxigen-fuel gas mixture, or any other suitable combustible gas mixture. A cage is provided between the two walls in which the ignition device is housed. The cage has a plurality of openings formed in the circumferential wall of the cage, and one of the combustion chamber wall has a plurality of openings spaced from the cage.
The combustion starts when the available fuel gas mixture is ignited with the ignition device, and a flame front, which exits the cage, begins to laminary expand over the volume of the combustion chamber with a certain velocity. The flame front pushes the unconsumed fuel gas mixture in front of it, with the gas mixture flowing through the openings formed in the one of the combusting chamber walls from the fore-chamber, which is defined by the two walls, into another chamber adjacent to the wall provided with the openings, which adjacent chamber is called a main chamber. The gas mixture penetrating into the main chamber causes there turbulence and pre-compression. When the flame front reaches the openings, the flame penetrates through the rather narrow openings in an accelerated manner in form of flame jets into the main chamber, causing their a further turbulence. The intermixed gas-air mixture in the main chamber is ignited over the entire surface of the flame jets. It bums with a high velocity which noticeably increases the effectiveness of the combustion, insuring that cooling-down losses remain small.
If the laminar flame front in the fore-chamber after ignition propagates with a relatively low speed, a comparatively long time passes between the ignition and beginning of combustion in the main chamber, which leads to high cooling-down losses. Because of slow combustion in the fore-chamber, on the other hand, the piston starts to move prematurely, before the pressure reaches its maximum and, therefore, means for retaining the piston in its initial position until the pressure reaches its maximum, need be provided. With slow combustion and conversion of the fuel gas mixture in the fore-chamber, the flame jets, which penetrate into the main chamber, do not generate in the main chamber, upon penetrating thereinto, a sufficient by high turbulence.
Accordingly, the object of the present invention is to provide a combustion-engined tool of the type described above in which a high velocity of the flame front in the fore-chamber in insured.
SUMMARY OF THE INVENTION
This and other objects of the present invention, which will become apparent hereinafter, are achieved by providing, between the ignition device and the openings in the combustion chamber wall separating the fore-chamber from the main chamber, means for localized swirling of the laminary expanding flame front formed in the fore chamber upon ignition of the fuel gas mixture with the ignition device.
The swirling device forms an obstruction in the fore-chamber in the path of propagation of the flame front, circumfluenting the same. As a result of interaction of the flame front with the obstruction, portions of the flame front are reflected from the obstacle or are deviated thereby, forming new flame front portions which increase the conversion rate of the fuel gas mixture. As a result, a localized turbulent combustion of the fuel gas mixture takes place, which results in a more rapid combustion of the entire gas mixture in the fore-chamber, which increases the propagation velocity of the laminar flame front. As a result, the cooling-down losses remain small. The flame jets, which penetrate into the main chamber are now capable to generate a sufficient turbulence when entering the main chamber. Therefore, the maximum pressure in the main chamber is obtained more rapidly, and the piston retaining means is not any more necessary.
The device for localized swirling of the ignited fuel-gas mixture in the fore-chamber can be formed as a separate, self-containing element, or be formed as additional structural components provided between the two walls. The swirling device can be formed, at least partially of wire, in particular, of a fine wire, in order to form simple, localized swirls. The swirling device can be formed, e.g., as a spring surrounding the ignition device and supported, at its opposite ends, against the two walls, respectively. As a spring, a helical spring can be used the advantage of which consists in that, upon collapsion of the combustion chamber, it can be compressed to a most possible extent, facilitating collapsing of the combustion chamber. Preferably, the spring is formed as a compression spring supported against the combustion chamber walls. In the compression spring, the distance between separate windings of the spring remains substantially the same which provides for a uniform distribution of the obstruction over the fore-chamber volume, which is circumfluented by the laminar flame front. This leads to a uniform conversion, as a result of the equipartition, of the fuel gas mixture.
Instead of a spring, the swirling device can be formed as a wire basket, which is formed of fine wire, with the bars extending perpendicular to the combustion chamber wall, and the like.
According to one of the embodiment of the invention, the device for swirling the flame front in the fore-chamber can be formed of structural elements associated with one or both combustion chamber walls. These structural elements can be formed as elements of facing each other surfaces of the two walls, e.g., as projections or recesses. The device-forming structural elements can be formed as steps provided in respective surfaces of the two walls. The surface elements of the two walls, which form the swirling device, can be arranged concentrically with the ignition device. Advantageously, the surface structural elements of the two wall are inversely arranged, so that the two wall can abut each other upon collapsing of the combustion chamber. In this case the projections on the surface of one of the wall would engage in the recesses formed in another of the walls, so that the walls can lie on each other.
The ignition device itself can be formed, e.g., of a pair of electrodes projecting into the fore-chamber. They are not necessarily need be surrounded by a cage. However, a cage can be used for housing the ignition device or the electrodes. When a cage is used, the swirling device is located outside of the cage, surrounding the cage and being spaced therefrom, a particularly high velocity of the flame front or the laminar flow is achieved.
It proved to be advantageous when the openings in the circumferential wall of the cage are angularity equidistantly spaced. The angularly equidistant spacing of the cage openings provides for symmetrical expansion of the laminar flame front in the fore-chamber to a most possible extent, and provides for symmetrical swirls of the flame front. This results in an overall improvement of the efficiency of combustion.
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.
BRIEF DESCRIPTION OF THE DRAWINGS
The drawings show:
FIG. 1
an axial cross-sectional view of an internal combustion-engined tool with a collapsed combustion chamber;
FIG. 2
an axial cross-sectional view of the tool shown in
FIG. 1
with an expanded combustion chamber.
FIG. 3
a
a side view of the ignition device of the combustion chamber shown in
FIGS. 1-2
together with a turbulence-creating device;
FIG. 3
b
a side view similar to that of
FIG. 3
a
but with another embodiment of a turbulence-creating device;
FIG. 4
a cross-sectional view line A—A in
FIG. 3
a;
FIG. 5
a cross-sectional view along line A—A in
FIG. 3
a
upon ignition; and
FIG. 6
a plan view of the separation plate of the combustion chamber upon ignition, with the ignition device cage being removed.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1
shows a cross-sectional view of an internal combustion engined-setting tool for setting fastening elements in the region of the tool combustion chamber. As shown in
FIG. 1
, the setting tool has a cylindrical combustion chamber
1
with a cylindrical wall
2
and an annular bottom
3
with a central opening
4
. A guide cylinder
5
, which has a cylindrical wall
6
and a bottom
7
, adjoins the opening
4
in the bottom
3
of the combustion chamber
1
. A piston
8
is displaceably arranged in the guide cylinder
5
. The piston
8
consists of a piston plate
9
facing the combustion chamber
1
and a piston rod
10
extending from the center of the piston plate
9
. The piston rod
10
projects through an opening
11
formed in the bottom
7
of the guide cylinder
5
.
FIG. 1
shows a non-operational position of the setting tool in which the piston
8
is in its rearward off-position. The side of the piston plate
9
adjacent to the bottom
3
of the combustion chamber
1
is located closely adjacent to the bottom
3
, with the piston rod
10
projecting only slightly beyond the bottom
7
of the guide cylinder
5
. For sealing the cylinder chambers on opposite sides of the piston plate
9
from each other, sealing rings
12
,
13
are provided on the outer circumference of the piston plate
9
.
Inside of the combustion chamber
1
, there is provided a cylindrical plate
14
further to be called a movable combustion chamber wall or movable wall. The movable wall
14
is displaceable in the longitudinal direction of the combustion chamber
1
. For separating the chambers on opposite sides of the movable wall
14
, an annular sealing
15
is provided on the circumference of the movable wall
14
. The movable wall
14
has a central opening
16
, with an annular sealing
17
provided in the wall of the opening
16
.
Between the movable wall
14
and the annular bottom
3
of the combustion chamber
1
, there is provided a further movable wall formed by a separation plate
18
. The separation plate
18
has a circular shape and an outer diameter corresponding to the inner diameter of the combustion chamber. The side of the separation plate
18
adjacent to the movable wall
14
is provided with a cylindrical lug
19
that projects through the central opening
16
in the movable wall
14
. The length of the lug
19
exceeds the thickness of the movable wall
14
in several times. The circumferential or annular sealing
17
sealingly engages the outer circumference of the cylindrical lug
19
. At its free end, the cylindrical lug
19
is provided with a shoulder
20
the outer diameter of which exceeds the outer diameter of the lug
19
and the inner diameter of the opening
16
of the movable wall
14
. Thus, upon moving away from the bottom
3
of the combustion chamber
1
, the movable wall
14
, in a while, engages the shoulder
20
of the lug
19
and lifts the separation plate
18
with it. Thus, the movable wall
14
and the separation plate
15
become spaced a predetermined distance which is determined by the position of the shoulder
20
. In this way, the movable wall
14
and the separation plate
18
form a so called fore-chamber, which forms a partial combustion chamber of the combustion chamber
1
. The fore-chamber is designated with a reference numeral
21
and is clearly shown in FIG.
2
. After the movable wall
14
engages the shoulder
20
, the movable wall
14
and the separation plate
18
are displaced together, and a further partial combustion chamber is formed between the separation plate
18
and the bottom
3
and/or the piston plate
9
. This further chamber forms a main chamber. It is designated with a reference numeral
22
and is likewise clearly shown in FIG.
2
.
For displacing the movable wall
14
, there are provided several, e.g., three drive rods
23
uniformly distributed along the circumference of the movable wall
14
and fixedly connected therewith. Only one of the drive rods
23
is shown in FIG.
1
. The drive rods
23
extend parallel to the axis of the combustion chamber
1
and outside of the cylindrical wall
6
of the guide cylinder
5
. The drive rods
23
extend through openings
24
, respectively, formed in the separation plate
18
and through corresponding openings
25
formed in the bottom
3
of the combustion chamber
1
. Each of the openings
25
is provided with a circumferential seal
26
located in the surface defining the opening
25
for sealing the combustion chamber
1
from outside. The movable wall
14
is connected with drive rods
23
by, e.g., screws
27
which extend through the movable wall
14
and are screwed into the drive rods
23
. The free ends of the drive rods
23
are connected with each other by a drive ring
28
which is arranged concentrically with the combustion chamber axis and which circumscribes the guide cylinder
5
. The drive ring
28
is connected with the drive rods
23
by screws
29
which extend through the drive ring
28
and are screwed into the drive rods
23
through end surfaces of the free ends of respective drive rods
23
. Each of the drive rods
23
supports a compression spring
30
extending between the bottom
3
of the combustion chamber
1
and the drive ring
28
. The compression springs
30
are designed for pulling the movable wall
14
toward the bottom
3
.
In the region of the bottom of the combustion chamber
1
, there is further provided a ventilation opening
31
into which a valve tappet
32
is sealingly extendable. With the ventilation opening
31
being open, the valve tappet
32
is located outside of the combustion chamber
1
or beneath the bottom
3
of the combustion chamber
1
. The valve tappet
32
is supported outside of the combustion chamber
1
by a shoulder
33
secured on the guide cylinder
5
. The shoulder
33
has an opening
34
through which a stub
35
, which is secured to the bottom side of the valve tappet
32
, extends. At the free end of the stub
35
, there is provided a shoulder
36
, and a compression spring
37
is arranged between the shoulder
36
and the shoulder
33
. The compression spring
37
is designed for pulling the valve tappet
32
toward the shoulder
33
to keep the ventilation opening
31
open. The cylindrical stub
35
lies in the displacement path of the drive ring
28
and is impacted by the drive ring
28
when the later is displaced toward the bottom
3
of the combustion chamber
1
. At a predetermined axial position, the drive ring
28
engages the stub
35
pushing it upward, so that the valve tappet
32
closes the ventilation opening
31
.
A plurality of further openings
38
are distributed over the circumference of the separation plate
18
at the same distance from the combustion chamber axis. In the lower end of the guide cylinder
5
, there are formed a plurality of outlet openings
39
for evacuating air from the guide cylinder
5
when the piston
8
is displaced toward the bottom
7
of the guide cylinder
5
. At the lower end of the guide cylinder
5
, there is provided damping means
40
for damping the movement of the piston
8
. When the piston
8
passes past the openings
39
, an exhaust gas can escape through the openings
39
.
Two radial, axially spaced openings
41
and
42
are formed in the cylindrical wall
2
of the combustion chamber
1
. Two outlet nipples
43
,
44
extend into the radial openings
41
,
42
, respectively, from outside. The nipples
43
,
44
form part of metering valves (not shown in detail) of a metering head
45
. A liquefied fuel gas is delivered to metering valves located in the metering head
45
from a bottle
46
. The metering valves provide for flow of a predetermined amount of the liquefied fuel gas through the outlet nipples
43
,
44
when the metering head
45
is pressed against the cylindrical wall
2
of the combustion chamber
1
, and the outlet nipples
43
,
44
are pushed inward, opening the respective metering valves. To provide for the inward movement of the outlet nipples
43
,
44
, the radial openings
41
,
42
narrow toward the interior of the combustion chamber
1
, providing stops for the outlet nipples
43
,
44
. The pressing of the metering head
45
against the cylindrical wall
2
is effected with a stirrup
47
pivotable at a hinge point
48
on the cylindrical wall
2
. One end
49
of the stirrup
47
is impacted by the movable wall
14
, and the stirrup is pivoted in such a way that its another end
50
is pressed against the metering head
45
to press the later toward the cylindrical wall
2
. The movable wall
14
engages the end
49
of the stirrup
47
shortly before the partial chamber
21
reaches its end position. The metering head
45
and the bottle
46
, once connected with each other, remain permanently connected. The system
45
/
46
can, e.g., tilt about an axle provided in the bottom region of the bottle
46
.
FIG. 2
shows the setting tool with the combustion chamber
1
in its expanded condition, i.e., with the expanded fore-chamber
21
and main chamber
22
. The displaced positions of the movable wall
14
and the separation plate
18
are established when the driving ring
28
impacts the shoulder
36
, closing the valve
31
,
32
. The opening
31
and the valve tappet
32
have conical circumferential surfaces narrowing in the direction of the combustion chamber
1
, so that a stop is formed. As it has been discussed previously, the distance of the separation plate
18
from the movable wall
14
is determined by the distance of the shoulder
20
from the separation plate
18
. In this position of the movable wall
14
and the separation plate
18
, the radial openings
41
,
42
lie against the fore-chamber
21
and the main chamber
22
, respectively.
The lug
19
forms, in its region adjacent to the separation plate
18
, an ignition cage
51
for receiving an ignition element
52
. The ignition element
52
serves for generating an electrical spark for the ignition of the air-fuel gas mixture in the fore-chamber
21
. As it will be described in more detail below, the ignition device
52
is located in the central region of the cage
51
having openings
53
formed in the cage circumference. Through those openings
53
, the burning gas exit from the ignition cage
51
into the fore-chamber. The ignition device
52
can include; e.g., two electrodes.
As further shown in
FIGS. 1-2
, the surface of the movable wall
14
, which faces the separation plate
18
, has an annular recess
54
concentric with the central opening
16
. A helical spring
55
extends in the recess
54
. In the collapsed condition of the combustion chamber, the spring
55
is completely compressed and is housed in the recess
54
, so that the movable wall
14
can lie on the separation plate
18
. In the expanded condition of the combustion chamber, which is shown in
FIG. 2
, the spring
55
is expanded or relieved to a most possible extent and is supported, at one of its end, in the recess
54
of the movable wall
14
and, at another of its end, against the separation plate
18
. In order to prevent the spring
55
from occupying an eccentric position, means (not shown) for securing respective ends of the spring
54
to movable wall
14
and the separation plate
18
can be provided.
The helical spring
55
is arranged concentrically with the cage
51
in a spaced relationship thereto. The helical spring
55
lies between the ignition device cage
51
and the openings
38
in the separation plate
18
. The helical spring
55
is formed of fine wire and forms an obstructions for a flame front that expands radially, upon ignition of the fuel gas mixture with the ignition device, from the cage
51
. Local turbulence of the expandable flame front is created in the region of the helical spring
55
. This local turbulence provides for better intermixing of the fuel gas mixture in the fore-chamber
21
. This results in a more rapid combustion of the fuel gas mixture in the fore-chamber
21
and, therefore, in an increase of the speed of the radially expanding flame front that remains substantially laminar.
Below, the operation of the setting tool, shown in
FIGS. 1-2
, will be described in detail.
FIG. 1
shows the condition of the combustion chamber
1
in the off-position of the setting tool. The combustion chamber
1
is completely collapsed, with the separation plate lying on the bottom
3
of the combustion chamber
1
and the movable wall
14
lying on the separation plate
18
. The piston
8
is in its rearward off-position so that practically no space remains between the piston
8
and the separation plate
18
if one would disregard a small clearance therebetween. The position, in which the movable wall
14
lies on the separation plate
18
, results from the compressing spring
30
biasing the drive ring
28
away from the bottom
3
, and the ring
28
pulls with it the movable wall
14
via the drive rods
23
. In this position, the drive ring
28
is spaced from the shoulder
36
of the valve tappet
32
, and the compression spring
37
keeps the valve tappet
32
outside of the opening
31
so that the opening
31
remains open. The system metering head
45
/bottle
46
is pivoted away from the wall
2
of the combustion chamber
1
, with the outlet nipples
43
,
44
being released and the metering valve (no shown) being closed. The helical spring
55
, which is formed as a compression spring is entirely compressed and is entirely housed in the recess
54
.
When in this condition, the setting tool is pressed with its front point against an object, the fastening element should be driven in. A mechanism, not shown, applies pressure to the drive ring
28
displacing it in the direction of the bottom
3
of the combustion chamber
1
. This takes place simultaneously with the setting tool being pressed against the object. Upon displacement of the drive ring
28
toward the bottom
3
, the movable wall
14
is lifted of the separation plate
18
and, after engaging the shoulder
20
, lifts the separation plate
18
with it. Upon engagement of the shoulder
20
by the movable wall
14
, the fore-chamber
21
is completely expanded but does not yet occupy its operational position inside the combustion chamber
1
. During the expansion of the fore-chamber
21
, the air can already been aspirated into the fore-chamber
21
through the ventilation opening
31
and through one or more of openings
38
formed in the separation plate
18
and overlapping the ventilation opening
31
.
Upon the setting tool being further pressed against the object, the drive ring
28
is moved closer to the bottom
3
,and the movable wall
14
is moved further upward, lifting the separation plate
18
from the bottom
3
. As a result, the main chamber
22
likewise expands and is aerated through the ventilation opening
31
, with the fore-chamber
21
being aerated through all of the openings
38
.
When the movable wall
14
and the separation plate
18
, in their movement upward, move past the radial openings
41
,
42
, in principle, the injection of metered amounts of liquefied fuel gas into the fore-chamber
21
and the main chamber
22
can begin. The injection starts when the movable wall engages the end
49
of the stirrup
47
which pivots in a clockwise direction about the pivot point
48
, with the other stirrup end
50
pressing the metering head
45
toward the cylindrical wall
2
. Upon the metering head
45
being pressed against the cylindrical wall
2
, the outlet nipples
43
,
44
move inward, opening the respective metering valves. The liquefied gas is injected into the fore-chamber
21
and the main chamber
22
. Thereafter, a further lifting of the movable wall
14
and the separation wall
18
is necessary to bring them into their end positions in which they are locked. The possible residual pivotal movement of the stirrup
27
is compensated by the outlet nipples
43
,
44
being moved a small distance further inward into the metering head
45
.
In the last part of the displacement of the moving wall
14
and the separation plate
18
to their end positions, the valve tappet
32
is pushed into the opening
31
, closing the same, as a result of the drive ring
28
engaging the shoulder
36
. The helical spring
55
is completely expanded and surrounds the cage
51
, extending between the movable wall
14
and the separation plate
18
.
The positions of the movable wall
14
and the separation plate
18
in the completely expanded condition of the fore-chamber
21
and the main chamber
22
is shown in FIG.
2
. In these positions, the movable wall
14
and the separation plate
18
can be locked. The locking takes place upon actuation of an appropriate lever or trigger of the setting tool. Upon actuation of the trigger, the movable wall
14
and the separation plate
18
become locked. The locking of the separation plate
18
and the movable wall
14
can be effected by locking of the drive ring
28
. Shortly after the locking of the movable wall
14
and the separation plate
18
, a ignition spark is generated by the actuation of the ignition element
52
inside the cage
51
. A mixture of air and the fuel gas, which was formed in each of the chambers
21
and
22
, is ignited. First, the mixture starts to bum laminary in the fore-chamber
21
, and the flame front spreads rather slowly in a direction of the openings
38
. First, the laminary flame front comes into contact with the helical spring
55
and is locally reflected or deviated. This increases the inter-mixing rate of the air-fuel gas mixture, resulting in a more rapid combustion and in an increased velocity of the laminar front, and the flame front reaches the opening
38
more rapidly. The unconsumable air-fuel gas mixture is displaced ahead and enters, through the openings
38
, the main chamber
22
, creating there turbulence and pre-compression. When the flame front reaches the openings
38
, it enters the main chamber
22
, due to the reduced cross-section of the openings
38
, in the form of flame jets, creating there a further turbulence. The thoroughly mixed, turbulent air-fuel gas mixture in the main chamber
22
is ignited over the entire surface of the flame jets. It burns with a high speed which significantly increases the combustion efficiency.
The combustible mixture impacts the piston
8
, which moves with a high speed toward the bottom
7
of the guide cylinder
5
, forcing the air from the guide cylinder
5
out through the openings
39
. Upon the piston plate
9
passing the openings
39
, the exhaust gas is discharged there through. The piston rod
10
effects setting of the fastening element. After setting or following the combustion of the air-fuel gas mixture, the piston
8
is brought to its initial position, which is shown in
FIG. 2
, as a result of thermal feedback produced by cooling of the flue gases which remain in the combustion chamber
1
and the guide cylinder
5
. As a result of cooling of the flue gases, an underpressure is created behind the piston
8
which provides for return of the piston
8
to its initial position. The combustion chamber
1
should remain sealed until the piston
8
reaches its initial position, shown in FIG.
2
.
After return of the piston
8
to its initial position, the movable wall
14
and the separation plate
18
are unlocked. The compression springs
30
bias the drive ring
28
away from the bottom
3
of the combustion chamber
1
, and the drive ring
28
releases the valve tappet
32
, and the compression spring
39
pushes the valve tappet
32
out of the opening
31
, opening same. Upon being displaced away from the bottom
3
by the compression springs
30
, the drive ring
28
pulls the movable wall
14
with it toward the bottom
3
. Later, as the drive ring
28
moves further away from the bottom
3
, the movable wall
14
abuts the separation plate
18
, pushing it toward the bottom
3
. Upon movement of the movable wall
14
and the separation plate
18
toward the bottom
3
, the exhaust gases in the fore-chamber
21
are pushed through the openings
38
in the separation plate
18
into the main chamber
22
and therefrom, together with the exhaust gases formed in the main chamber
22
, through the opening
31
outside. Finally, the separation plate
18
lies again on the bottom
3
, and the movable wall
14
lies on the separation plate
18
. The combustion chamber
1
becomes completely collapsed and free of exhaust gases. The aeration process can start again.
FIGS. 3-5
show the construction of the cage
51
for the ignition device
52
. In the expanded condition of the fore-chamber
21
, the cage
51
is located between the movable wall
14
and the separation plate
18
, as shown in
FIGS. 3
a
-
3
b.
The cage
51
is formed as a cylindrical body and has an inner chamber in which the ignition device
52
for generating an electrical spark is located. The cylindrical wall of the cage
51
has, in the embodiment of the tool described here, four outlet openings
53
having an elongate shape, with the longitudinal direction of the openings
53
being perpendicular to the movable wall
14
and the separation plate
18
. The openings
53
have, at least in their central region, a width such that the wall surfaces
53
a,
which limit the opening
53
, are so arranged that the walls
53
a
of adjacent openings
53
adjoin each other at a right angle. Flame expands from the center of the cage
51
parallel to the movable wall
14
and the separation plate
18
and, therefore, does not impact the inner surfaces of the cage
51
which extend perpendicular to the propagation direction of the flame front. As a result, a reflection of the flame back to the cage center is prevented. This favorable influences the laminar flow of the flame which expands radially shortly after living the cage
51
. The cage
51
, as shown in
FIG. 3
a,
is in the center of the helical spring
55
which concentrically surrounds the cage
51
in a spaced relationship thereto. The cage
51
is supported against the movable wall
14
and the separation plate
18
.
FIG. 6
shows a plan view of the separation plate
18
according to another embodiment. In this embodiment, no cage
51
is provided. Only, the ignition device
52
, which is indicated with arrows, is located in the center of the cage
51
. The flame front F, which is formed at a distance from the ignition device
52
, is locally swirled by the helical spring
55
, but remains substantially laminar when it reaches the openings
38
in the separation plate
18
. As an ignition device
52
, e.g., a spark plug can be used.
It should be clear that instead of the helical spring
52
, another swirling means can be used for creating a local turbulence which can be arranged between the ignition device
52
and the openings
38
. E.g., as swirling means, steps
56
a
/
56
b,
which are shown in
FIG. 3
b,
can be used. The steps
56
a
/
56
b
can be formed, respectively, in the movable wall
14
and the separation plate
18
. Advantageously, the steps
56
a
/
56
b
are inversely arranged in the movable wall
14
and the separation plate
18
, which provides for complete abutment of movable wall
14
and the separation plate
18
. The steps
56
a
/
56
b
permit to achieve the same effect as the spring
55
.
Though the present invention was shown and described with references to the preferred embodiments, such embodiments are merely illustrative of the present invention and are not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is therefore not intended that the present invention be limited to the disclosed embodiments or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims.
Claims
- 1. A combustion-engined tool, comprising two opposite combustion chamber walls (14, 18); and an ignition device (52) arranged between the two opposite combustion chamber walls (14, 18) for igniting a fuel gas mixture occupying space between the two walls (14, 18), one (18) of the two walls having a plurality of openings (38) spaced from the ignition device; and means located between the ignition device (52) and the openings (38) formed in the one of two walls (18) for localized swirling a laminary expanding flame front formed upon ignition of the fuel gas mixture with the ignition device.
- 2. A combustion-engined tool according to claim 1, wherein the swirling means (55) is formed as a separate element.
- 3. A combustion-engined tool according to claim 2, wherein the swirling means is formed at least partially of wire.
- 4. A combustion-engined tool according to claim 1, wherein the swirling means is formed as a spring (55) surrounding the ignition device (52) and supported at its opposite ends against the two walls (14, 18), respectively.
- 5. A combustion-engined tool according to claim 4, wherein the spring is formed as a helical spring.
- 6. A combustion-engined tool according to claim 4, wherein the spring is formed as a compression spring.
- 7. A combustion-engined tool according to claim 1, wherein the swirling means (56a, 56b) forms part of at least one of the two combustion chamber walls (14, 18).
- 8. A combustion-engined tool according to claim 7, wherein the swirling means (56a, 56b) is formed by structural modification of the at least one of the two walls.
- 9. A combustion-engined tool according to claim 8, wherein the swirling means (56a, 56b) comprises step means formed in the at least one of the two walls.
- 10. A combustion-engined tool according to claim 8, wherein the steps means (56a, 56b) comprises inverse steps (56a, 56b) formed in both of the combustion chamber walls (14, 18), respectively.
- 11. A combustion-engined tool according to claim 1, further comprising a cage (51) surrounding the ignition device (52) and having openings (53) in the circumferential wall thereof; and wherein the swirling means (55, 56a, 56b) is located between the cage (51) and the openings (38) of the one of the two walls (18).
- 12. A combustion-engined tool according to claim 11, wherein the openings (53) in the circumferential wall (51) of the cage are angularity equidistantly spaced.
- 13. A device according to claim 11, wherein the cage (51) is formed as a hollow cylinder, a longitudinal axis of which extends transverse to the combustion chamber walls (14, 18).
- 14. A combustion-engined tool according to claim 11, wherein the cage (51) forms part of a lug (19) connected with one (18) of the two combustion walls (14, 18) and extends through an opening (16) formed in another (14) of the two combustion chamber walls (14, 18).
- 15. A combustion-engined tool according to claim 11, wherein wall sections (53a) of a cage wall surrounding adjacent cage openings (53) abut each other at inner ends thereof.
Priority Claims (1)
Number |
Date |
Country |
Kind |
100 07 211 |
Feb 2000 |
DE |
|
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Number |
Name |
Date |
Kind |
4442807 |
Latsch et al. |
Apr 1984 |
A |
4513708 |
Latsch et al. |
Apr 1985 |
A |
4766861 |
Finsterwalder |
Aug 1988 |
A |
4987868 |
Richardson |
Jan 1991 |
A |