Field of Art
[0001] The invention relates to fuel injection for a two-stroke combustion engine.
Background Art
[0002] A two-stroke engine for karts must be reliably supplied with an igniting mixture
of gasoline and air in a required quantity and with a required air-to-gasoline ratio
depending on the engine load and its rotation speed. Currently, this is ensured by
a carburetor, which is, however, considered to be an imprecise device, with which
a number of complications is connected, mainly in terms of maintenance, tuning, and
high demands for specific experience in its use.
Summary of the Invention
[0003] The defects of the current state of the art are eliminated by an injection unit for
fuel injection defined in claim 1.
[0004] The proposed solution represents a more accurate and easier-to-operate device able
to control the fuel injection electronically. In comparison to a carburetor, this
allows for a higher engine operation efficiency with lower emissions and lower fuel
consumption.
[0005] The injection unit is placed directly onto the engine block so that the injection
unit body is fixed via a flange of a reed valve directly into the intake channel of
the cylinder. An air filter is mounted on the opposite side of the injection unit
body.
[0006] Apart from the injection unit itself, a number of components, which are interdependent
to a large extent, are also a part of the fuel injection unit. The whole system comprises
2 fuel injector pieces, also a control unit, which sends out electronic impulses to
the injectors after an analysis of data from sensors - an air pressure and temperature
sensor, a throttle opening sensor, a crank position sensor for determining current
engine rotation speed, sensor for water temperature measurement. The fuel supply to
the injectors is provided using a gasoline pump and regulated by means of a fuel pressure
regulation sensor. All electrical components are connected via a cable harness.
[0007] The proposed solution is unique in terms of the shape and location of the two injectors
and the air pressure and temperature sensor in the injection unit body so that the
injectors are activated efficiently, according to the needs of the engine based on
the current rotation speed.
Brief Description of Drawings
[0008]
Fig. 1 illustrates assembly comprising an injection unit with two injectors, a throttle,
an acceleration regulation system, and sensors.
Fig. 2 illustrates a cross section of an injection unit body showing the position
of the injector relative to the throttle, the shape of the interior channel, and the
axis of the injection unit body.
Fig. 3 schematically illustrates a cross section of both injectors, where the position
of the injectors is determined by a V-shape.
Exemplifying Embodiment of the Invention
[0009] An injection unit for fuel injection comprises an injection unit body 1. The injection
unit body 1 includes an interior channel, wherein two injectors 2 for fuel injection
into the interior channel of the injection unit body 1 lead into the injection unit
body 1. A throttle 3 is arranged in the interior channel, the throttle 3 being controllable
by a gas acceleration regulation system 4 for regulating flow of the mixture into
a combustion chamber. An air temperature and pressure sensor for measuring pressure
conditions and temperature is in the injection unit body 1.
[0010] The interior channel is positioned along the axis of the injection unit body 1 and
it has a shape where, in the upstream direction, it has a constant diameter, then
follows a narrowing of the channel in the range of 5° - 30° and then a radius R of
35-45 mm, to provide a correct linear flow in this channel.
[0011] The injectors 2 are placed relative to each other in a position, which is determined
by a V-shape and forms a mutual angle in the range of 30° - 70° and forms an angle
relative to the channel axis of the injection unit body 1 in the range of 30°-65°.
[0012] The pressure and temperature sensor is positioned with an angle in the range of 55°
-85° relative to the axis of the injection unit body 1.
[0013] A carburetor installation space is identical to the injection unit installation space.
The injection unit body 1 is made from an aluminium alloy.
[0014] The principle of suction of the mixture into the combustion chamber is the same as
for any two-stroke engines for karts. During the intake stroke, an amount of mixture
corresponding to the required performance is delivered into the combustion chamber.
The cadence of opening and the amount of the mixture is determined by the control
unit based on an analysis of data from the sensors. The flow of the mixture into the
combustion chamber is further regulated by closing and opening the throttle 3, which
is controlled via an acceleration regulation system 4. The throttle is used in engines
with a carburetor as well as with fuel injection.
[0015] The position of the two pieces of injectors 2 and the position of the sensors placed
in the injection unit body 2 is angularly (or even also dimensionally) dependent on
each other. These specific positioning angles ensure the proper functioning of the
injection unit. During the process, pressure and negative pressure waves are formed
within the unit and due to the arrangement, the proper functioning and subsequent
data analysis in the control unit can be ensured. The interior shape of the injection
unit body channel, which also influences the pressure changes, is also important for
the proper functioning of the unit.
[0016] The control unit provides electrical impulses to the injectors, which supply the
fuel mixture to the unit. The cadence of these impulses is dependent on the engine
speed. The correctness of the impulse cadence during a speed change is provided using
a pre-set data analysis map, which is based on empirical development.
Industrial Applicability
[0017] The principle that is the subject of the invention can be used for any two-stroke
engines.
1. Injection unit for fuel injection,
characterized in that it comprises an injection unit body (1) including
an interior channel, wherein two injectors (2) for injecting fuel into the interior
channel of the injection unit body (1) are placed in the injection unit body (1),
a throttle (3) connectable to an acceleration regulation system (4) for regulating
flow of the mixture into combustion chamber, and
air temperature and pressure sensor for measuring temperature and pressure conditions.
2. Injection unit according to claim 1, characterized in that mutual position of the injectors relative to each other forms a V-shape including
an angle in the range of 30° - 70° and the injectors include an angle with the channel
axis of the injection unit body (1) in the range of 30°-65°.
3. Injection unit according to claim 1 or 2, characterized in that the position of the temperature and pressure sensor includes with the axis of the
injection unit body (1) an angle in the range of 55° - 85°.
4. Injection unit according to claim 1 or 2 or 3, characterized in that the interior channel is arranged along the axis of the injection unit body (1) and
has such a shape, that a part of the interior channel has a constant diameter, following
this part of the interior channel is a cone-shaped channel narrowing with an apex
angle in the range of 5° to 30° and then follows a radius (R) in the range of 35 to
45 mm.
5. Injection unit according to any of the preceding claims, characterized in that a control unit providing electronic impulses for opening the injectors has a preset
map for analysis of data from the sensors of pressure, temperature, engine rotation
speed, and throttle (3) position, via using coefficients, for a precise time cadence
of opening the injectors and thus a precise determination of the amount of mixture
injected.