DE19753702A1 - Fuel injection device for an internal combustion engine and method for controlling it - Google Patents

Abstract

The present invention relates to a fuel injection device of an internal combustion engine 10 of a hand-held tool with a fuel return line and a control part 20, in particular for a single-cylinder, two-stroke internal combustion engine, a temperature sensor 22 being provided for measuring the current fuel temperature T¶K¶, the temperature sensor 22 with the Control part 20 is connected via a measured value transmission path 25. Here, the temperature sensor 22 is arranged on an injection valve 16, on the fuel return line and / or in or on a tank.

Description

The invention relates to the fuel injection device of an internal combustion engine of a hand-held tool with a fuel return line and a control part, in particular for a single-cylinder internal combustion engine, a temperature sensor being provided for measuring the instantaneous fuel temperature T _K , the temperature sensor being connected to the control part via a measured value transmission path, according to the The present invention further relates to a method for controlling a fuel injection device of a hand-held tool, in particular for a single-cylinder, two-stroke internal combustion engine, according to the preamble of claim 4.

For optimal control of the fuel injection device Internal combustion engine are the current operating state of the Internal combustion engine descriptive parameters measured and control data such as for example, ignition timing, amount of fuel injected, injection timing etc. adjusted accordingly by the control. This primarily serves the goal smooth running and optimal power output from the Internal combustion engine with the lowest possible emissions with a wide variety of operating conditions, for example with regard to reverse temperature, humidity, engine temperature or load condition guarantee.

For this purpose it is known to measure the engine temperature and from this one derive current engine operating status. However, this has the disadvantage that the engine temperature the actual operating conditions by a relatively slow heat conduction and that to be heated on the engine large masses always lagging behind and actually an operating state from the Past corresponds. In addition, especially in engines that are in Hand tools are an additional heating of the fuel "hot" due to the immediate vicinity of the tank or fuel lines Engine parts. Accordingly, engine control is rough and inaccurate based on this temperature value. In particular, only cold and Warm start can be distinguished and changes due to fuel density different temperatures are not taken into account. In unfavorable cases thereby the fuel-air mixture formed in a combustion chamber of the engine lean a critical area and cause loss of performance and engine damage to lead.  

DE 43 35 866 A1 describes a non-return fuel Conveyor system for an internal combustion engine known, at which a conventional pressure regulator uses a fuel return line unnecessary and problems due to a bil formation of fuel vapors in the tank avoids that a precise regulation of a speed of a fuel pump to achieve an optimal intake manifold / fuel manifold differential pressure in both normal and at high fuel temperatures. A temperature output signal from a measurement of a fuel temperature serves to modify a reference differential pressure Error between an output signal from a fuel diff reference pressure sensor means and the reference differential pressure to be sided. However, this system does not include coupling between fuel temperature and engine condition, since none Fuel reflux takes place. Such a fuel back On the contrary, the river is said to be according to the invention according to DE 43 35 866 A1 become superfluous. Accordingly, he allows here fuel temperature made no conclusions about you current engine condition and any necessary adjustments the engine control with regard to the ignition angle or ignition timing, amount of fuel injected or the like.

From DE 42 41 459 A1 there is also an electronic control er device for an internal combustion engine, which to differentiate between different fuels, as with for example regular gasoline, heavy gasoline or an alcohol mixed gasoline, a fuel property sensor used, which determines a refractive index of the fuel. Each according to the type of fuel detected, immediately after Mon Gate start is an amount of air and / or power supplied to the motor amount of substance varies accordingly. However, since the refraction dex of the fuel also depends on its temperature is, a temperature measurement signal to compensate for the tem temperature dependence of the refractive index. This too However, the system has the disadvantage that it detects an engine condition only via conventional parameters, such as the  Engine temperature, takes place and accordingly saves or time react with a delay to changes in the engine status can.

It is an object of the present invention to provide an improved Fuel injector and a control method available for this device of the type mentioned above make, which eliminates the disadvantages mentioned above and guarantee a better and more differentiated engine control continuous

This task is accomplished by a fuel injector the above Species with the characteristics marked in claim 1 len and through a control procedure of the above Kind with the Process steps characterized in claim 4 solved.

For this purpose, it is provided according to the invention that the temperature sensor on an injection valve, on the fuel return flow line and / or is arranged in or on a tank.

This has the advantage that an additional parameter for Mo Gate state detection is present and also a change in density of the fuel recognized and correspond to the engine control is reacted to. Without additional effort in the sensor area rich is an integration of the invention into existing ones Systems, for example simply by software adaptation, possible.

Further developments of the device are preferably shown in FIGS Claims 2 and 3 described.

For quick and time-efficient processing of the measurement values and for optimal control results is also in advantageously provided a memory, which tempe rature limits for the fuel temperature, the Intervals between the temperature limits predetermined Mo gate states are assigned.  

A further differentiated and op Timally adapted control results from the fact that the over carry further engine status values a second measured value transmission path from the engine to the control part is provided.

In a method of the type mentioned above, the following steps are provided according to the invention to solve the problem:

• (a) measuring a temperature T _{K of} a fuel,
• (b) deriving a current operating state of the internal combustion engine from the fuel temperature T _K ,
• (c) Calculate the current operating state of the Internal combustion engine optimal control data,
• (d) delivering control signals to the internal combustion engine according to the calculated tax data.

This has the advantage that an additional parameter for Mo Gate state detection used and also a density change tion of the fuel is recognized and the engine control can react accordingly. Without additional effort in Sen sorbereich is an integration of the invention in the best existing systems, for example, only through software adaptations possible.

Further developments of the method are preferably shown in FIGS Claims 5 to 12 described.

Steps (a) to (d) are expediently zy repeated cliché.

The result is a particularly simple and effective arrangement if, in step (a), the fuel temperature T _{K is} measured at an injection valve, in a fuel return line and / or a fuel tank.

A further differentiated and optimally adapted to each operating state control results from the fact that in step (a) further parameters, such as intake air temperature T _L , exhaust gas temperature T _A , component temperature T _B , intake air pressure p and / or speed n of the internal combustion engine are measured and in step (b) are taken into account.

For a quick, time-economical processing of the measured values and optimal control results, the fuel temperature T _K is advantageously compared with data stored in a map in step (b).

The control data in step (c) are expediently an injection quantity, an injection angle Inj _Alpha , an ignition point, an ignition angle and / or an injection duration Inj _t . Step (d) is preferably crank angle-synchronized and the control signals in step (d) are delivered to the internal combustion engine in an advantageous manner as a function of at least one reference signal. This least least one reference signal is preferably a trigger signal, in particular a Hall sensor pulse J _Hall and / or an ignition pulse J _ignition .

The invention based on the attached drawing nations explained in more detail. These show in

Fig. 1 is a schematic block diagram of a preferred embodiment of the control according to the invention and

Fig. 2 is a plan view of a preferred embodiment of an injector for a fuel injector according to the invention.

The exemplary embodiment shown in FIG. 1 of a fuel injection system 100 shows a high-speed two-stroke internal combustion engine 10 with fuel injection. The engine 10 comprises a cylinder 13 in which a piston 11 moves up and down. The piston 11 also controls the suction of the combustion air, which is sucked in via an inlet channel 15 (shown schematically by an arrow 15 ), in a conventional manner via overflow channels and inlet slots. For the discharge of the combustion gases, an outlet channel 12 (also shown by an arrow) is provided. The fuel is, controlled by an electromagnetically actuated injection valve 16 , injected obliquely upwards through an injection channel 17 into the cylinder 13 and the hemispherical combustion chamber 14 arranged in the cylinder head. After formation of the mixture, the ignition takes place by means of a spark plug 23 which projects into the combustion chamber 14 and is connected to the ignition 18 .

In general, more fuel is delivered to the injection valve 16 than is actually injected into the combustion chamber. Excess fuel flows back into a fuel tank through a return line. The compression of the fuel fuel by the injection pump leads to a heating of the fuel, so that the tank contents are heated by the fuel flowing back. With increasing operating time, this effect increases, so that the fuel temperature at the injection valve 16 rises, as more and more preheated fuel is removed from the fuel tank and is further heated by the compression in the injection pump. If the engine 10 is cold, the fuel at the valve 16 is also cold. If the engine 10 is warm (repeat start), the fuel at the valve 16 is also normally warm.

Furthermore, the heating of the fuel leads to a density change and thus to a mismatch in the injection duration to the actual engine operating condition when the force fabric temperature not taken into account by the motor control becomes. The fuel-air mixture in the combustion chamber is lean  due to the reduced density of the fuel with increased Fuel temperatures in a critical range now and then thus leads to reduced performance during operation and possible damage to the engine.

According to the invention, the fuel temperature T _K at the injection valve 16 is now measured and evaluated as an additional indicator of an engine operating condition detection, so that the control data, such as Inj _Alpha or Inj _t, are set accordingly as a function of the fuel temperature at the injection valve 16 .

For this purpose, the fuel injection system 100 comprises a control part 20 , which is particularly preferably a computer. The computer 20 receives the fuel temperature T _K as an input variable and, if appropriate, further parameters which also characterize the operating state of the two-stroke internal combustion engine 10 . These parameters are measured in a first step on the injection valve 16 or on the two-stroke internal combustion engine 10 and are transmitted to the computer 20 via measured value transmission lines 25 and 26 shown in broken lines. From these parameters, the computer 20 calculates in a second step egg ne the current operating state of the engine 10 appropriate or optimal injection quantity or an injection duration Inj _t or the required ignition angle or timing.

To calculate these values, a map is used, for example, which has the characteristic values for the respective injection quantity and the respective ignition angle as a function of the load state of the engine 10 and its operating parameters. This map K = f (load, T ₁ , T ₂ , p, n,...) Is stored, for example, in a map memory 21 which the computer 20 accesses. The values calculated in this way can either be used immediately by the computer 20 or stored as characteristic values K 'in a further characteristic value memory (not shown) for further processing and temporarily stored.

In the actual control of the internal combustion engine 10, it holds the corresponding control pulses for the ignition 18 and the injection valve 16 from the computer 20 , in accordance with the calculated control data, so that the injection quantity, injection angle Inj _Alpha , ignition timing, ignition angle and / or injection duration Inj _t for the current operating and the load state of the engine 10 are optimally set or executed.

The delivery of control signals from the computer 20 to the corre sponding units 16 , 18 of the internal combustion engine 10 is preferably carried out as a function of speed-dependent trigger signals, for example an ignition pulse J _ignition and / or a Hall sensor pulse J _Hall . The Hall sender pulse J _Hall , for example, comes from a Hall sender that is additionally arranged on the engine and marks another crank angle. Such an additional pulse is particularly advantageous if a different start of the trigger is required at greatly different speeds in order to avoid disturbances in the synchronism of the motor.

The computer 20 uses the fuel temperature T _K and possibly other engine status data, such as intake air temperature T _L , exhaust gas temperature T _A , component temperature T _B , intake air pressure p and / or speed n of the internal combustion engine, and sets according to these values and the trigger impulses J _ignition and J _Hall, for example, the injection start and / or the injection quantity, the injection angle Inj _Alpha , the ignition timing, the ignition angle and / or the injection duration Inj _t and controls the injection valve 16 with the values Inj _Alpha and Inj _t accordingly. In addition, the ignition 18 can also be controlled via the ignition angle.

A limit case arises when the engine is started again immediately after refueling. Here the engine would be warm and the fuel cold. However, this state can be known on the one hand by monitoring other parameters, on the other hand it is not critical, since in the worst case the computer 20 briefly operates the engine with too much fuel supply, ie too rich. Here, however, there is no danger to the engine 10 .

The evaluation of the fuel temperature at the injection valve 16 according to the invention can advantageously also be combined with the recording and evaluation of further parameters describing the engine state, such as, for example, intake air temperature T _L , exhaust gas temperature T _A , component temperature T _B , intake air pressure p and / or speed n Internal combustion engine 10 .

The injector 28 shown in Fig. 2 comprises an injection valve 16 , a valve connector 30 and a breather attachment 32 with connection to a fuel tank, not shown. In the valve connector 30 , the temperature sensor 22 for measuring the fuel temperature T _{K is} easily seen. A measured value transmission path 25 , for example in the form of an electrically conductive cable, connects the sensor 22 to a control part (not shown in FIG. 2).

Reference list

100

Fuel injection system

10th

Internal combustion engine

11

piston

12th

Exhaust duct (combustion gases)

13

cylinder

14

Combustion chamber

15

Inlet duct (combustion air)

16

Injector

17th

Injection channel

18th

ignition

20th

Control section

21

Characteristic value memory

22

Temperature sensor

23

spark plug

25th

Measured value transmission path

26

Measured value transmission path

28

Injector

30th

Valve connector

32

Breather attachment
Inj _Alpha

Injection angle
Inj _t

Injection duration
J _ignition

Firing pulse
J _Hall

Hall sensor pulse
T _K

Fuel temperature

Claims (12)

1. Fuel injection device of an internal combustion engine ( 10 ) of a hand tool with a fuel return flow line and a control part ( 20 ), in particular for a single-cylinder two-stroke internal combustion engine, a temperature sensor ( 22 ) for measuring the instantaneous fuel temperature T _{K being} provided, the tempera Door sensor ( 22 ) is connected to the control part ( 20 ) via a measured value transmission path ( 25 ), characterized in that the temperature sensor ( 22 ) is arranged on an injection valve ( 16 ), on the fuel return line and / or in or on a tank . 2. Apparatus according to claim 1, characterized in that a memory ( 21 ) is further provided, which contains temperature limits for the fuel temperature, where the intervals between the temperature limits are assigned to certain engine states. 3. Device according to one of claims 1 or 2, characterized in that a second measured value transmission path ( 26 ) from the motor ( 10 ) to the control part ( 20 ) is provided for transmitting further engine state values. 4. Method for controlling a fuel injection device of a hand-held tool, in particular for a single-cylinder, two-stroke internal combustion engine, characterized by the following steps,

• (a) measuring a temperature T _{K of} a fuel,
• (b) deriving a current operating state of the internal combustion engine from the fuel temperature T _K ,
• (c) calculating the optimal control data for the current operating state of the internal combustion engine,
• (d) supplying control signals to the internal combustion engine in accordance with the calculated control data.

5. The method according to claim 4, characterized in that in step (a) the fuel temperature T _{K is} measured at an injection valve, in a fuel return line and / or a fuel tank. 6. The method according to claim 4 or 5, characterized in that steps (a) to (d) are repeated cyclically. 7. The method according to any one of claims 4 to 6, characterized in that in step (a) further parameters, such as intake air temperature T _L , exhaust gas temperature T _A , component temperature T _B , suction air pressure p and / or speed n of the internal combustion engine measured and taken into account in step (b). 8. The method according to any one of claims 4 to 7, characterized in that in step (b) the fuel temperature T _{K is} compared with data stored in a map. 9. The method according to any one of claims 4 to 8, characterized in that the control data in step (c) are an injection quantity, an injection angle Inj _Alpha , an ignition timing, an ignition angle and / or an injection duration Inj _t . 10. The method according to any one of claims 4 to 9, characterized in that Step (d) is carried out synchronized with the crank angle. 11. The method according to any one of claims 4 to 10, characterized in that in step (d) the control signals to the internal combustion engine machine depending on at least one reference signal are given. 12. The method according to claim 11, characterized in that the at least one reference signal is a trigger signal, in particular a Hall encoder pulse J _Hall and / or a Zün dimpuls J _ignition .