Note: Descriptions are shown in the official language in which they were submitted.
CA 022~1764 1998-10-13
S,, C I F I C ~ I I 0 N
Hand-ocerated tool with an internal combustion engine
with electronic direct injection
TECHNICALAREA
The invention reLates to a hanc-operated tool, more particu-
larly cutting bisks, brush cutters or the like, with an i1-
ternal combustion engine, preferably a two-stroke ensine
with electronic direct injection of the fuel, which is pro-
vided with a cooling fan dis~osed on the crankshaft and,
within the area of the cylinder, with a cooling air guicance
means which brings about a flow along the crankshaft axis.
STATE OF THE ART
When fuel is injectec into the internal com~ustion engire,
it is attempted to perform this in such a way that a gccc
mixture preparation with a simu~taneous optimization of -,1e
waste gas quality is achieved.
In the DE 41 42 354 A1, a tool is disclosed which ~ossesses
a block of injection pumps that is secured to a moun~
plate separating the intake sec ion for the combustion a-r
from the engine space. However, this leads to an incre_sed
thermal stress of the injection ~ump block since the la-ter
forms a compact unit with the mounting plate so that the
waste heat from the engine space is passed on direct to
the parts carrying fuel, whereby a gassing of the fuel re-
sults.
Also from the DE 37 35 711 A1, a hand-operated tool is known.
In this tool, the injection pumo is flexibly connected with
the engine so as to avoid mechanical and thermal stresses
acting upon the injection pump. Elut it is preciselythe fle-
xible connection which harbours new problems because the fle-
xible pipeline makes an exact control diificult and since,
on account of it being routed through non-cooled regions -
close to the engine - the risk of the fuel being gassed li-
kewise exists.
CA 022~l764 l998-l0-l3
DESCRIPTION OF THE INVENTION
That is why the tecrnicGl problem of the invention is .o oo i-
mize two-stroke internal combustion engines of the type in
question or their fuel injection.
This technical problem is resolved by the features characteri-
zed in the Claim 1.
To this end provision is made according to the invention, par-
ticularly in power cnain saws wherein the cylinder is disposed
so as to be arrangec! vertically or inclined relative to the
chain blade axis, for the intake chamber with the filter to he
located on the side of the handle and for the coolins blowe~
f~ t~
CA 022~1764 1998-10-13
cooling air guicance means is alloca.ed to the cylinder,
;his brings about a flow alons the axis of the crankshc ~,
,or a partition adjacent to the cylinder se~aratins the
continguous intake chamber from the cooling air guidance
means and for dis~osing the fuel injection valve above tle
inlet duct for the drawn-in air in the cylinder, by pre-
,erance with an inclination toward the cylinder head and
while penetrating the partition.
Preferably, an in.ake section secured to .he cylinder wi.h
he inlet duct, is constructed so as to overlap the fuel
injection valve above the inlet duc. and as a pressure ele-
ment for the same.
According to a preferred embociiment, the intake sec~,on is
equipped with current supply contacts for the elec.ronic_lly
con.rolled ,uel injection valve, in which case tre int-k
sec.ion can inc~rporate the fuel supply or ,uel evacua ion
,or the electromagnetically controlled fuel injec.ion valve.
Further,~ore, the intake sec.ion may be provided wi;h an air
fil er and/or an air guidance path with a device or cooling
the ,uel.
According to a further preferred embodiment, the intake sec-
tion is equipped with â multipoint plug on an intake air
housing, which also forms the partition to the cylinder,
in .he operational state it is in engagement, while the
intake air housing possesses the controller for supplying
the internal combustion engine.
More especially a power chain saw, with an internal combus-
tion engine and a fuel injection system is often--integra-
ted into the housing of the tool, as well as the fuel tank
and a supply container for lubricating oil and the cooling
air guidance means.
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CA 022~1764 1998-10-13
In fuel injecrion systems in mctor vehicles it is known to
dispose the Fressure controlLer in the fuel tank direc~
or in the region o, the fuel cistribution on the engine in
;heengine space.
In a hand-controlled tool, in order to arrange the pressure
controller of the fuel pipe system of the fuel injection
system of the internal comous.ion engine in a favorable
manner from a spa ial, opera.ional and cooling-technic_l
point of view, provision is made accordins to the inven ion
for disposing the pressure con rol valve of the fuel injec-
tion system in or on the fuel tank.
The pressure control valve is in this case prefercbly to
be positioned in such a way ~.at the scme ccdi ionally pro-
jects into the cis.ribu.~r s 5 ce of the cocling cir or is
mounted in the same.
Advantageous fur-her develocments of the invention are chc-
racterized in the subclcims.
eRrEF DESCRIPT ON OF THE DRA~-NGS
In the followins, embodiment examples of the invention are
explained in greater detail wi h the aid OT the drawinss.
Thus:
F i 9. 1 shows in a schematic view a first embodiment of
a power chain saw with the disposition of the
pressure controller according to the invention;
F i 9. 2 shows in a schematic view a second embodiment of
a power chain saw with the disposition of the
pressure controller according to the invention;
F i 9. 3 shows in a schematic view a third embodiment of a
power chain saw with the disposition of the pres-
sure controller according to the invention, and
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CA 022~l764 l998- l0- l3
~ i 9. 4 shows in a schematic view a fourth embodlment of a
power chain saw wi.h the disposition of the pres-
sure con.roller accordirs to the invention
BEST WAY OF REALIZING THE INVENTION
The power chain saw 1û depicteb in Fig. 1 is in a normal manner
equipped with an internal combustion engine not shown in gre3-
ter detail in a hcusing 11, a chain blade 12, a handle 13 and
other fixtures.
On the top side 1L of the housing 11, the cylinder 15 projec.s,
which, in the dirr-ction of the chain blade 12, supports an ex-
haust 16 and, in .1e direction of the other side, a fuel in-
jection valve 17 and an intake section 18. Between the cylin-
der 15 and the fue~ injection valve 17 as well as .rhe intake
section 18, a bulkheab wall 19 is located, which is consti.u-
ted of an intake air housing 20 hith the inlet duc 15a anb
the outlet duct 15b and a cooling air housing 21 for the cy-
linder 15, in which case the inta~e air housing 20 is compri-
sed of a housing cover 20a anc the housing bottom 20b.
The fuel injection valve 17 is cisposed above the intake sec-
tion 18 so as to be directed cbliquely upwardly, while bo~h
devices penetrate the partition 19.
The electronic controller 22 is mounted in the intake housing
2û. The intake section 18 is ~rovided with an air filter 23.
The throttle valve connection piece 24 is additionally mounted
in the intake sec.ion 18.
With the aid of the waste gas sensor 25 disposed within the
area of the exhaust 16 or inside the outlet duct 15b of the
cylinder 15, it is possible to determine the waste gas tem-
perature for the controller 22.
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An optimal operational behavior is achieved when the ,uel
pump not shown in the drawinc in or on the ,uel tank 2~,
is disposed in the intake air stream 27 or in the coolinc
air stream 28.
The power chain saw 10 depic.ed in the Figs 2 through L j5
comprised of a basic housing 11, on which a handle 13 and
the chain blace 1Z are dis~osed. Inside the basic housi,-g
11, the fuel tank 26, a supply container tor lubricating
oil, the cooling air guicance means and the in.ernal co,-
bus.ion engine are loca.ed, which are not illus.rated i~
greater detail here as well as other normal means. Loc- ed
on the basic housing 11 or, rather, projecting from the
same, is the cylinder 15, cn which the magne,ic injec~i~n
valve 31 as well as a-mear,s ,or the in.ake o,~ combus.icn
air are ciisposed.
The fuel tank 26 is providec on the side 38 of the bas
housing 11 loca.ed opposi.e the chain blade 12 wi.hin . e
area of the handle 13. The pressure controller 35 is p~ ced
in .he basic housing 11, .o be more precise, in tha par.,
in which also the fuel tank 26 is to be found.
In the embodiment depicted in Fig.2, in the intake air
housing 20 mounted on the basic housing 11, the intake sec-
tion 32 with the fuel return pipe 34, an electronic consrol-
ler 30 and the magnetic injection valve 31 are disposec.
Ihe pressure controller 35 of the fuel injection sys.em is,
according to the invention, disposed externally on the 'uel
tank 26 in the intake air stream 36. The air stream 29 is
produced by the magnet wheel/fan wheel 28 and conducted
from the basic housing 11 to the cooling air housing 37.
In the embodiment illustrated in the Fig.3, in contrast to
the embodiment shown in the Fig.2, provision has been made
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for the pressur~ controller 3, of the fuel injec.ion system
to be disposed sn .he e~.er or of the fuel tank 2~ in tne
intake air s.re-m 36 and this, accordins to .'e inven~-lon,
so as to projec~ in.o the ir,.ake air housing 20.
In the emoodiment depic.ed in Fig.4 on the otner hand, pro-
vision has been made for the pressure controller 35 for the
fuel injection sys.em to be dis~osed on the fuel tank 26,
which is intesrated into the basic housing 11.
CA 022~1764 1998-10-13
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LIST OF REFEREi~C-- 'Jb'i~aERS
Power chain saw 10
housing 11
chain blade 12
handle 13
tG p side 1 L
cylinder 15
cylinder inlet duct 1Sa
cylinder outlet duc. 1Sr.
exhaust 16
fuel injection valve 17
intake sec'ion 18
bulkhead wall 19
intake air housing 20.
intake air housing, cover 2Qa
intake air housing, bc.-am 20r
cooling air housing 21
electronic controllar 22
air filter 23
throttle valve connection F ~arr 24
waste gas sensor 25
fuel tank 2S
intake air stream 27
cooling air stream 28
magnet wheel/fan wheel 29
electronic controller 30
magnetic injection valve 31
intake section 32
fuel return flow pipe 34
pressure controller 35
intake air stream 36
cooling air housing 37
side 38
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