KR0185589B1 - Method and apparatus for controlling a fuel pump - Google Patents

Abstract

Method and apparatus for controlling electromagnetic valve operation of timeline pump

The method and apparatus for controlling electromagnetic valve operation of an internal combustion engine fuel pump is responsible for determining the drive signal of the valve based on the marks on the shaft of the engine, and the fuel delivery start time (WB) and end time (WE) are controlled by the valve. Is determined. In order to determine the drive signal (fifth 5c), the marts on the shaft are counted as well as interpolation B1 or B2 is performed over time between the marts (figure 5b). This interpolation depends on the instantaneous rotational speed detected just before interpolation.

Description

Method and apparatus for controlling electromagnetic valve operation of fuel pump

1 is a schematic diagram of a fuel delivery control device for an internal combustion engine.

2A-2D are diagrams showing a cam stroke, a drive signal of an electromagnetic valve, a valve stroke, and a synchronous pulse in the operation of the apparatus.

3A-3C are diagrams showing scattering of fuel amount during different fuel delivery start times.

4 is a schematic diagram of a control device of the device, in particular a device for forming a valve drive signal.

5A-5C are diagrams showing the relationship between the camshaft rotational speed versus the drive signal and the relationship between the mark and the drive signal on the angle increment of the camshaft.

6A-6E are diagrams showing a sequence of different signals for adjusting the fuel injection start time.

* Explanation of symbols for main parts of the drawings

10: fuel pump 15: pump piston

20: electromagnetic valve 30: electronic control device

32: regulator 55: increment wheel

60: camshaft 70: transmitter

90 measuring device 92 transmitter wheel

The present invention relates to a method and apparatus for controlling electromagnetic valve operation of an internal combustion engine, in particular a fuel pump for a fuel injection diesel engine.

A method and apparatus for this purpose are described in DE-OS 35 35 811.

In the specification of this publication, a control system of a fuel pump (self-controlled by an electromagnetic valve) for a diesel engine is described.

The pump has a piston moving in the pump chamber and is driven by the cam shaft of the engine. The piston delivers fuel to the pump chamber under pressure so that fuel is injected into each cylinder of the engine through the fuel inlet.

An electromagnetic valve is installed between the fuel tank and the pump chamber, and the electronic control device applies control pulses to the valve so that the valve opens and closes according to these control pulses.

Accordingly, the pump piston delivers fuel into the engine combustion chamber in accordance with the switching state of the valve. The drive pulse determines the exact fuel injection start time and fuel injection end time and the amount of fuel to be injected. Mechanical determination of the fuel amount by the control groove is not necessary. An increment wheel is provided on the camshaft to define the drive pulse. A counter that counts the marks on the wheel begins to count after the generation of the sync pulse. After counting the number of preset marks, the control device sends a drive pulse to the valve indicating the start of fuel injection.

The fuel delivery end time is determined through an additional count on the increment mark.

This device has the disadvantage that the metering of fuel is relatively inaccurate. Since the drive pulse is determined by the count from the increment wheel, the accuracy of weighing depends on the precision of the wheel mark. In addition, fuel delivery start and end times are not very precisely determined.

Due to the tolerance of the product, only a finite number of teeth can be arranged so that the mark on the wheel constitutes a relatively large space, which is also a disadvantage in the accuracy of weighing.

A method for determining the exact fuel delivery start time via an electromagnetic valve disposed between the pump chamber and the fuel supply is known from the specification (DE-OS) 35 40 313 in the German (federal) publication. The fuel injection end time and the amount of fuel to be injected are determined by the mechanical component.

The calculation of the drive pulse for the fuel injection start time is done in a similar manner as described in DE-OS 35 40 811. In response to the generation of the sync pulse, the value on the increment wheel is recalculated. If the fuel injection start time lies between two marks of the increment wheel, the remaining balance is interpolated. This interpolation is based on the value of the rotational speed averaged over several operating cycles.

In this case, there is a problem that the rotational speed of the engine and the period of rotation of the engine vary. When the average rotational speed value is given in DE-OS 35 40 313, the interpolation becomes very inaccurate if the speed changes during weighing. The system of DE-OS 35 40 313 compensates for these problems with correction factors according to the parameter field, but this compensation also does not provide a sufficiently accurate value for the fuel injection start time. Since the fuel injection end time is determined by a mechanical component, an error in fuel delivery start time also causes an error in fuel injection amount.

Therefore, it is desired to determine as accurately as possible the timing of the valve for the definite fuel injection start time and fuel injection end time.

According to a first aspect of the present invention, there is provided a method for controlling the operation of an electromagnetic valve of an internal combustion engine fuel pump, which pump delivers fuel to a cylinder of an engine under pressure and the start and end times of fuel delivery are defined by the valve. All. The method includes determining the drive signal of the valve by counting the marks based on the marks on the shaft of the engine and interpolating between the marks over time based on the instantaneous rotational speed detected immediately before interpolation. have.

According to a second aspect of the invention, there is provided an electromagnetic valve actuation control apparatus for an internal combustion engine fuel pump, which pump delivers fuel to a cylinder of an engine under pressure and the start and end times of fuel delivery are defined by the valve. All. The apparatus includes means for counting the marks based on the marks on the shaft of the engine and determining the drive signal of the valve by performing interpolation between the marks based on the instantaneous rotational speed detected immediately before interpolation.

With interpolation between the marks, the accuracy of the fuel delivery or injection end time as well as the fuel delivery or injection start time can be determined relatively precisely. By referring to the instantaneous rotational speed just before interpolation, the accuracy of the interpolation value can be increased.

The method and apparatus of the present invention will now be described in more detail with reference to the accompanying drawings.

1 shows a control device of a fuel pump for a diesel engine controlled by an electromagnetic valve. Fuel is injected into each cylinder of the engine by the fuel pump 10. The fuel pump has a pump piston 15 driven by the camshaft 60, and has a flow relationship with the electromagnetic valve 20. It is arranged. The valve 20 is operated by switching pulses coming from the electronic control device 30 through the power output stage 40. The electronic control device 30 includes a regulator 32. Transmitter 70 disposed in valve 20 or fuel injector (not shown) supplies signals to control device 30.

An angle mark is provided on an increment wheel 55 mounted on the cam shaft 60. The wheel has at least one incremental cap IL, which can be defined as absent teeth, teeth different from the rest, or other suitable teeth.

The measuring device 50 detects a pulse initialized by the angle mark and the rotational temperature of the wheel 55 and supplies a corresponding signal to the control device 30.

The measuring device 90 recognizes the marks 92 on the transmitter wheel 92 mounted on the crankshaft of the engine and supplies a corresponding signal to the control device 30. Data relating to additional parameters such as rotation speed n, temperature T and rod FP (accelerator pedal point), etc., is supplied to control device 30 via input 80.

The control device 30 carries the fuel delivery start time WB and the fuel delivery of the fuel pump 10 based on the parameters supplied via the input 80 and the rotational motion of the pump cam shaft 60 detected by the measuring device 50. Determine the angle WD.

With the values for the fuel delivery start time WB and the fuel delivery angle WD, the control device 30 calculates the start and end times of the drive signal AS for the power output stage 40. This calculation is performed by having the valve 20 at the point in time WB be positioned at the first point at which fuel transport and injection takes place, and at the point in time WE at the second point where the fuel pump no longer injects. The calculation may also be performed based on one or more rotational speeds n, temperature T or accelerator pedal or signal FP indicating the desired travel speed.

The camshaft 60 drives the pump piston in such a way as to pressurize the fuel in the pump 10. In this case, the electromagnetic valve 20 controls the pressure generation. The valve 20 may also be installed in the pump in such a way that the fuel delivery is initiated by the closing of the magnetic valve or the fuel delivery is started by the opening of the valve. . The method of the present invention can be utilized in two variations of the valve function.

If the device is installed in such a way that no pressure is generated when the valve 20 is opened, pressure is generated in the pump 10 only when the valve 20 is closed. A valve (not shown) is opened at a predetermined pressure at the fuel pump where fuel is injected into the combustion chamber of the engine through the injector.

The transmitter 70 checks the time point at which the valve 20 opens or closes. Mounting the transmitter 70 to the injector presents the particular advantage that the transmitter can generate a signal indicating the actual start time SB or preparation time of fuel injection into the combustion chamber.

The regulator 32 compares the output signal of the transmitter 70 and the signal of the measuring device 90 with a preset target value. When the shift occurs, the regulator 32 changes the fuel transport start time WB value. Instead of the output signal of the transmitter 70, it is possible to use a signal indicating the position where the valve is disposed. This signal is obtained by calculating the current flowing through the valve or the voltage across the valve.

FIG. 2a shows the cam stroke NH which is somewhat larger than the combustion period, FIG. 2b shows the drive signal AS of the valve 20, FIG. 2c shows the valve stroke MH and FIG. 2d shows the synchronous pulse S, respectively. Starting from this sync pulse S, the fuel delivery start time WB and the fuel delivery start time WE are determined. The electronic control device 30 generates a drive signal of the valve 20 at an angle WD after the sync pulse S. After a short delay time VT, the valve 20 enters the second switching state. From this time point FB, the pump 10 carries fuel.

After the passage of the angle WD defining the fuel delivery duration D, the drive signal AS of the valve is withdrawn again. After another delay time, the valve opens and fuel delivery ends at the FE. Between the closing at FE and the opening at FE of valve 20, the cam travels through distance H (khem stroke).

The cam stroke H determines the injection amount of fuel, which is directly proportional to the cap stroke H.

When the cam speed C is constant, the amount of fuel injected does not depend on the fuel delivery start time WB. The ratio of cam stroke to elapsed time is expressed as cam speed C.

If the cam speed C is not constant, a change in fuel amount occurs when there is a change in fuel delivery start time and a change in duration D of the valve 20 drive signal.

Inconsistent cam speed may be caused, for example, due to a change in rotational speed during fuel injection.

In FIG. 3a, the cam stroke NH is represented as a function of time, and in FIG. 3b the cam speed C is represented as a time function. In FIG. 3C, the voltage UM across the valve 20 for two fuel injection phases I1 (indicated by solid lines) and I2 (indicated by dashed lines) is indicated as a function of time.

In this case, the start time WB of the fuel injection phase is changed to a very small amount of DFB. The fuel delivery angle WD remains the same in both phases. If the cam speed rises with time, the cam stroke H1 is in the first injection phase and the cam stroke H2 is in the second injection phase. The cam moves only the cam stroke H1 smaller than the cam stroke H2 of the second phase during the first phase. As a result, a larger amount of fuel is injected in the second phase than in the first phase. In fuel injection, pure time control based on different rotational speed processes is not possible. The rotational speed change is caused, for example, by elasticity in the drive connection between the crankshaft and the camshaft.

Therefore, the amount of fuel Q injected into the engine depends on the closing time and instantaneous rotational speed N of the valve 20. In this case, a relationship of Q = fuel transport ratio x WD is established, where the fuel transport ratio indicates the amount of fuel to be injected per angle unit. Fuel delivery angle WD = 6 × N × D where D represents fuel delivery duration.

4 through 6a-6e illustrate a method of eliminating the dependency of the injected fuel amount on an unsystematic change in rotational speed.

4 illustrates the electronic control device 30 in more detail, which is composed of a weighing computer 120, parameter fields K1 and K2 and a computer 110. A signal from the rotational speed sensor that detects the instantaneous rotational speed N of the camshaft is transmitted to the computer 120. A signal indicative of the desired fuel delivery angle WD and the desired fuel delivery time WB is also applied to the computer 120. Signals WD and WB are generated from fields K1 and K2, respectively. The intermediate rotation speed nM and the desired fuel quantity Q serve as input magnitudes for fields K1 and K2 respectively. The signal Q is generated from the computer 110 which calculates the desired fuel quantity Q according to different input magnitudes provided via sensors for detecting, for example, intermediate rotational speed nM, temperature T, accelerator pedal point FP and other operating parameter magnitudes.

The fuel delivery angle WD is read from the field K1 based on the values of the injected fuel amount Q and the intermediate rotation speed nM, and determines the amount of fuel to be injected. This is the angle pivoted by the camshaft when the fuel pump carries fuel. The intermediate rotational speed nM can be derived from different sensors, preferably from sensors that detect pulses from the pulse wheels on the crankshaft or camshaft. In this case, the rotation speed is averaged over a larger angular range or averaged over several revolutions of the shaft. This signal can also be derived from an alternative rotational speed sensor, for example a fuel injection start sensor.

The fuel delivery start time WB is read out from the field K2 based on the injected fuel amount Q and the average rotational speed nM. This is the angle at which fuel injection begins. Computer 120 converts these angular signals WD and WB into time magnitudes based on the instantaneous rotational speed N. These magnitudes determine the drive signal of the valve 20. Thus, the computer 120 determines the point in time at which the voltage across the magnetic valve changes.

(See also part 2b). These values are supplied to the power stage 40, and are converted into the drive signal AS by this power stage.

Now, the conversion of the angular magnitude to the temporal magnitude will be described with reference to FIGS. 5A-5C.

Figure 5a shows a typical rotational speed process in the injection phase or injection metering. Rotational speed decreases linearly as a function of time in the phase process. The pulse that the measuring device 50 derives from the mark of the increment wheel 55 is shown in FIG. 5B. Each mark on the wheel produces a pulse in the device 50. It is of particular advantage if the space between the two angle marks, ie the measuring angle MW, is smaller than the minimum fuel delivery angle WD. A 3 ° measurement angle has special advantages, in which case 120 angle marks in 3 ° space are applied to the wheel. Such wheels are particularly suitable for engines with four, five, six and eight cylinders. As already mentioned above, at least one increment gap IL that generates the sync pulse S appears in the sync wheel. The angle from the start of this sync pulse to the fuel delivery start time WB and fuel delivery end time WE is displayed. Fuel improvements occur over the fuel delivery angle WD, which lies between the fuel delivery start time WB and the fuel delivery end time WE. The angle for WB is divided into the integral angle component WBG for fuel delivery start time and the residual angle RWE for fuel delivery start time or corresponding residual time TB. The iterative addition to the times TB and TE for the angles RWB and RWE is made on the basis of the instantaneous rotational speed N. In this case, each residence time T is derived from the residual angle RW and the instantaneous rotational speed N, which is expressed by the formula T = RW / (6 * N). The rotational speed underlying the interpolation of time TB and TE is obtained from the measurement angle MW which lies as close as possible to the respective interpolation distance. By using the new rotation speed value as much as possible, the error can be made smaller.

The first calculation is specified as B1 in Figure 5b. The camshaft turns the measuring angle MW at the measuring time MT. The first value for the instantaneous rotational speed N is calculated and interpolation is performed at the calculation time TR. After the calculation time TR, the actual residence time TB remains. The calculation time must in any case end before the injection phase. If the fuel delivery start time WB is not reached, a new interpolation is made. The instantaneous rotational speed N is detected through the first measurement angle, and interpolation is performed at the calculation time TR of the second calculation B2. The interpolation error due to the change of the camshaft rotational speed can be kept low through iterative calculation of the instantaneous rotational speed value. The detection and interpolation of the instantaneous camshaft rotational speed N must be started no later than the fuel delivery start time WB by the measurement time MT and the calculation time TR. Therefore, detection and interpolation of the camshaft rotational speed are performed in a time interval equal to the sum of the measurement time MT and the calculation time TR just before the desired fuel delivery start time WB.

The process for the fuel delivery end time is repeated. At an additional calculation time, the first value for the instantaneous rotational speed is newly calculated and interpolation is performed. After the calculation time, the actual residence time TE remains. This calculation time must end before the fuel injection phase ends. If the fuel delivery end angle WE is not reached, a new interpolation is performed. The instantaneous rotational speed N is detected via an additional measuring angle and interpolation is performed. As described above, the interpolation error due to the change of the camshaft rotational speed becomes smaller through iterative calculation of the instantaneous rotational speed value, and the detection and interpolation of the instantaneous speed N at the end of fuel transportation by the measurement time MT and the calculation time TR at least. It must be started before time WE. Therefore, the cam chart rotational speed is detected and interpolated in a time interval equal to the sum of the measurement time MT and the calculation time TR just before the desired fuel delivery end time WE. The actual fuel delivery start time is utilized in the calculation of the fuel delivery end. The error in the calculation of the residence time during the fuel delivery start time can be corrected through the calculation of the fuel delivery end time.

In a system with a preliminary injection, the calculation of the fuel delivery start time and fuel delivery end time for the preliminary injection and the main injection is carried out according to the above-described method.

Since the angles for fuel delivery start time and fuel delivery end time are formed through subsequent time interpolation as well as counting integral angle marks, the incremental angle time system can be regarded as the metering principle.

Synchronization of the cylinder requires at least one increment gap IL on the increment wheel as described above.

As an alternative, a Z-cap may be provided, in which case cylinder identification is required. This synchronization gap can also be replaced with a corresponding synchronization mark other than the residual mark.

In order to achieve optimal combustion, injection must be performed at the correct position of the piston. Therefore, the fuel delivery start time and thus the fuel injection start time are related to the top dead center of the piston and hence the crankshaft. The optimum point of fuel delivery start is obtained when the fuel delivery start time is related to the signal coming from the sensor in the crankshaft.

If the initialization of the fuel delivery start time is made based on the signal from the camshaft, a substantial shift of the fuel delivery start time occurs from the preset optimal fuel delivery start time. This shift is due to various influences, for example, elasticity in driving the cam shaft from the crankshaft. This shift in the system can be eliminated through the adjustment circuit.

6A-6E illustrate this adjustment circuit. The generation of the synchronization signal S as a function of time is input to FIG. 6A. 6B shows the drive signal AS. The signal SB indicating the actual start of implantation is shown as a function of time in FIG. 6C. This signal SB comes from the transmitter 70. The signal OT of the measuring device 90 is shown in FIG. 6d. The signal OT is closely related to the top dead center of the piston. The space SBI between the signal SB indicating the actual fuel injection start and the signal OT of the measuring device 90 is transmitted to the regulator 32 as shown in FIG. 6E. The spatial SBI can be expressed in angular magnitude or time units. The regulator 32 has at least a proportional function but has particular advantages when it has an integral component. The regulator 32 compares the signal SBI indicating the actual fuel injection start with the preset target value SBS. Based on this comparison, a correction for the fuel delivery start time is performed. At the next fuel injection phase or measurement, the drive signal occurs at the corrected fuel delivery start time WBK and not at the fuel delivery start time WB.

The initialization of the drive signal is related to the synchronous mart S applied to the camshaft. The position of the actual fuel injection start SBI is detected in relation to the measurement mark OT on the camshaft. In this case, the measurement mark is arranged in the top dead center region of the piston. Signal processing is performed at the angular magnitude, the time magnitude, or the angular magnitude and the time magnitude.

Since the fuel delivery start time is adjusted from the crankshaft signal and the calculation of the fuel amount is performed in accordance with the rotation of the camshaft, relatively accurate fuel injection can be made into the system.

In order to eliminate disturbing influences, segment wheels may alternatively be arranged on the crankshaft. Thus, a segment wheel is arranged on the cam shaft for the purpose of synchronizing the cylinders. The system in which the respective increment wheels are arranged on the cam shaft and the crankshaft can have special advantages.

Claims (6)

A method of controlling a fuel pump for an internal combustion engine of a vehicle, the fuel pump having a piston driven by a crankshaft of the engine to pressurize fuel located in the fuel pump. Determining the amount of fuel flowing from the fuel pump based on at least one input variable indicative of operating conditions of the vehicle, continuously measuring the instantaneous rotational speed of the crankshaft, flow-start angle and flow-end Determining an angle, wherein each angle is based on the current average speed of the determined amount of fuel flowing from the fuel pump and the measured rotational speed of the crankshaft, and the flow-start angle is a first integer angle. (integral angle) and the first fractional angle (residual angle) divided into, the measurement immediately before the conversion of the first fractional angle Converting the fractional angle into a first residual time value based on only the instantaneous current rotational speed of the crankshaft and generating a trigger signal to initialize fuel flow from the fuel pump at the end of the first residual time value; Splitting the end angle into a second integer angle and a second decimal angle, converting the second residual time value based on only the instantaneous current rotational speed of the crankshaft measured immediately before the conversion of the second decimal angle, and generating the trigger signal. Stopping the flow of fuel from the fuel pump at the end of the second remaining time value. The method of claim 1, wherein each of the first and second integer angles corresponds to a plurality of spaced-angle indications located on the crankshaft. The method of claim 1, wherein the at least one input variable is selected from the group comprising an average rotational speed of the crankshaft, a peripheral engine and a gas pedal position of the vehicle. An apparatus for controlling a fuel pump for an internal combustion engine of a vehicle, said apparatus comprising: a fuel pump for pressurizing fuel located in said fuel pump, including a piston driven by a crankshaft of said engine, and an amount of fuel flowing from said fuel pump; A sensor for detecting at least one input variable and transmitting an output signal in response thereto, a measuring device for continuously measuring the instantaneous rotational speed of the crankshaft, coupled to an output of the sensor and the measuring device and exiting from the sensor A first processing device for determining an amount of fuel flowing from the fuel pump in response to an output signal and for determining a flow-start angle and a flow-end angle based on the determined average amount of fuel and a current average of measured rotational speeds of the crankshaft; The flow-start angle coupled to the output of the first processing device and to the output of the measurement device Is divided into a first integer angle and a first decimal angle, and is converted into a first residual time value based only on the instantaneous current rotational speed of the crankshaft measured immediately before the conversion of the first decimal angle and generates a trigger signal. Initializing fuel flow from the fuel pump at the end of one remaining time value, dividing the flow-ending angle into a second integer angle and a second decimal angle, so that the instant of the crankshaft measured immediately before the conversion of the second decimal angle And a second processing device for converting the second residual time value based on only the current rotation speed and transmitting the trigger signal to stop the fuel flow from the fuel pump at the end of the second residual time value. Fuel pump control device for internal combustion engines. 5. The fuel pump control apparatus for an internal combustion engine of a vehicle according to claim 4, wherein each of said first and second integer angles corresponds to a plurality of spaced-angle indications located on said crankshaft. 6. The fuel pump control apparatus for an internal combustion engine of a vehicle according to claim 5, wherein at least one input variable comprises an average rotational speed of the crankshaft, an ambient engine temperature and a position of a gas pedal of the vehicle.

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