EP2724012A1

EP2724012A1 - Method for operating a fuel delivery device

Info

Publication number: EP2724012A1
Application number: EP12718204.6A
Authority: EP
Inventors: Uwe Richter; Joerg Kuempel
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2011-06-22
Filing date: 2012-05-02
Publication date: 2014-04-30
Also published as: WO2012175248A1; CN103649506A; US20140224222A1; KR101898881B1; CN103649506B; JP2014517213A; DE102011077987A1; JP5976104B2; KR20140035948A; US9303582B2

Abstract

The invention relates to a method for operating a fuel delivery device (10) of an internal combustion engine, in which method an electromagnetic actuating device (20) of a volume control valve (22) is switched such as to set a delivery volume, wherein a control of the electromagnetic actuating device (20) for moving an armature (46) of the electromagnetic actuating device (20) from a first position to a second position comprises at least three phases (68, 70, 72), wherein in a first phase (68) a coil (44) of the electromagnetic actuating device (20) is permanently connected to a voltage, and wherein in a second phase (70) the coil (44) is periodically connected to the voltage with a first frequency (76) and with a first duty factor (78), and wherein in a third phase (72) the coil (44) is periodically connected to the voltage with a second frequency and with a second duty factor.

Description

Description title

Method for operating a fuel conveyor state of the art

The invention relates to a method according to the preamble of claim 1, and a drive circuit, a computer program and a control and / or regulating device according to the independent claims.

Quantity control valves, for example in a fuel delivery device of an internal combustion engine, are known from the market. Rate control valves are generally operated electromagnetically and are often part of a high-pressure pump of the fuel delivery device. The quantity control valve controls the amount of fuel flowing to a high-pressure accumulator, from where the fuel is passed to the injection valves of the internal combustion engine. For example, the quantity control valve has two switching states, between which can be switched by means of an electronic control.

A patent publication in this field is, for example, EP 1 042 607 B1.

Disclosure of the invention

The problem underlying the invention is solved by a method according to claim 1 and by a drive circuit, a control and / or regulating device and a computer program according to the independent claims. Advantageous developments are specified in subclaims. For the invention important features can be further found in the following description and in the drawings, the features both alone and in different combinations for the Invention may be important, without being explicitly referred to again.

The inventive method has the advantage that an electromagnetic actuator of a quantity control valve by means of a

Pulse width modulated voltage can be controlled very easily and inexpensively, with good switching properties are possible. A current control of the power amplifier by means of switching thresholds is not required. The applied electrical energy or electrical power loss, as well as the achievable speed of the armature movement, eventual

Tolerances of the armature operating time and the operating noise are comparable with the properties of a current-controlled control. A

Oversizing the electromagnetic actuator is also not required. With regard to conventional actuators with pulse width modulation, the control according to the invention of the output stage requires less electrical power and has a lower thermal load.

The invention relates to a method for operating a

Fuel delivery device of an internal combustion engine, in which an electromagnetic actuator of a arranged in an inlet to a delivery chamber of the fuel delivery device quantity control valve is switched to adjust a flow rate. For this purpose, the electromagnetic actuator is in each switching operation in which an armature of the electromagnetic actuator, for example, to be moved against the force of an armature spring in the direction of a stroke stop, by means of

Control energy supplied. The control is carried out by means of a pulse width modulation. For example, this will be one

Battery voltage ("voltage") repeatedly and at least temporarily periodically connected to a coil of the electromagnetic actuator.

In accordance with the law of induction, this results in sections approximately ramp-shaped time profiles of the current flowing through the coil.

The control of the electromagnetic actuator or the coil is such that the armature from a first position - generally from a rest seat - in a second position - generally to a stroke stop

- is moved. The control according to the invention comprises at least three phases. In a first phase, the coil is continuously switched to the voltage for a comparatively short period of time. In a subsequent second phase, the coil is periodically switched to the voltage at a first frequency and at a first duty cycle. In a

subsequent third phase, the coil is in turn periodically connected to a second frequency and with a second duty cycle to the voltage. In this case, the first and the second duty cycle are generally different from each other. Preferably, the second duty cycle is set such that a mean electric power is lower during the third phase than during the second phase.

An embodiment of the invention provides that a respective duration of the three phases and / or the first frequency and / or the second frequency and / or the first duty cycle and / or the second duty cycle as a function of the voltage and / or a temperature and / or or a line resistance and / or a rotational speed of the internal combustion engine can be adjusted. The temperature is for example a temperature of the coil and the

Line resistance is a lead resistance of a cable for connecting the coil to a drive circuit, which is preferably arranged in a control and / or regulating device of the internal combustion engine. Thereby, the control of the electromagnetic actuator - so the coil - are particularly adapted to each operating conditions. Thus, on the one hand, a fast and reliable switching of the electromagnetic actuator or the quantity control valve, and on the other hand, an optimized energy consumption can be achieved.

Furthermore, the invention provides that the first and the second phase cause a starting phase of the armature, and that the third phase causes a holding phase of the armature. The tightening phase is the phase in which the armature is moved by magnetic force from the rest seat to the stroke stop. The hold phase is that phase in which the armature is held in place by a - generally lower - magnetic force on the stroke stop. In this way, an optimized control can be carried out for the tightening phase and the holding phase. In particular, the method according to the invention can be advantageously used to simulate a conventional so-called "current-controlled" control of the electromagnetic actuator and to replace it almost equally, with a considerable effort can be saved. A "current controlled" driver generally uses lower and upper current thresholds to control the current flowing through the coil using hysteresis. If the lower current threshold is undershot, the coil is switched to the voltage. If the upper current threshold is exceeded, the coil is switched off by the voltage. This results in an oscillating time curve of the coil current between the two current thresholds.

For a current-controlled activation, the energy W to be applied during the starting phase is proportional to an integral of the current I over the starting time t: t-suit, end

- Suit, beginning

For the activation according to the invention, the energy W to be applied during the starting phase is likewise proportional to an integral of the current I over the starting time t:

The control according to the invention is preferably dimensioned such that an equality of the energies W to be expended during the starting phase results:

3-phase current controlled

This means in the present case that a sum energy of the control of the coil according to the invention during the first and the second phase to a sum energy of the current-controlled control during the tightening phase is the same or should be the same as possible. This is done by means of a suitable dimensioning of the duration of the three phases and / or the first

Frequency and / or the second frequency and / or the first duty cycle and / or the second duty cycle. In addition, a sum energy of the control of the coil during the third phase to a sum energy of the current-controlled control during the holding phase can be approximately the same or be made as equal in a comparable manner.

The inventive method is simplified when the respective duration of the three phases and / or the first frequency and / or the second frequency and / or the first duty cycle and / or the second duty cycle is determined using at least one map. The map can be the above-mentioned dependence on the voltage, the coil temperature, the

Line resistance and / or the speed of the internal combustion engine particularly simple and safe account. Optionally, the map for a particular series of quantity control valves can be determined once on a test bench, and stored, for example, in a data memory of the control and / or regulating device of the internal combustion engine.

A further simplification of the invention is when the first frequency is equal to the second frequency. Thereby, a simplified clock generation for driving the electromagnetic actuator can be used, wherein the different during the second and the third phase average electrical power substantially by a respective

Duty cycle can be adjusted.

Furthermore, the invention comprises a drive circuit for actuating the electromagnetic actuating device of the quantity control valve, which has means for carrying out an activation by means of at least three phases according to at least one of the preceding claims.

According to the invention, the control takes place via a pulse width modulation of the voltage generating the drive power. The necessary electronic circuit is simple and inexpensive to produce. The inventive method is scalable within wide limits, so that it is often not necessary to different structural embodiments of

Provide drive circuit. The method is particularly easy to carry out if it is carried out by means of a computer program on the control and / or regulating device ("control unit") of the internal combustion engine, in particular using the map described above. In a preferred embodiment, the device is set up by loading the computer program with the features of the independent computer program claim from a storage medium. The storage medium is understood as meaning any device that contains the computer program in stored form.

Hereinafter, exemplary embodiments of the invention will be explained with reference to the drawings. In the drawing show:

Figure 1 is a simplified diagram of a fuel delivery of a

Internal combustion engine;

Figure 2 is a sectional view of a high-pressure pump of

A fuel delivery device together with a quantity control valve and an electromagnetic actuator;

Figure 3 is a timing diagram of a control of the electromagnetic

Actuating means; and

Figure 4 is a simplified block diagram to supplement the method.

The same reference numerals are used for functionally equivalent elements and sizes in all figures, even in different embodiments.

FIG. 1 shows a fuel delivery device 10 of an internal combustion engine in a greatly simplified representation. From a fuel tank 12 is fuel via a suction line 14, by means of a feed pump 16, via a

Low pressure line 18, and one of an electromagnetic

Actuator 20 ("solenoid") operable quantity control valve 22 of a high-pressure pump 24 is supplied. Downstream is the high pressure pump 24 connected via a high-pressure line 26 to a high-pressure accumulator 28 ("common rail"). Other elements, such as valves of

High-pressure pump 24, are not shown in the figure 1. The

Electromagnetic actuator 20 is controlled by means of a control circuit 31 arranged on a control and / or regulating device 30.

Furthermore, the control and / or regulating device 30 has a computer program 32 and a map 34.

It is understood that the quantity control valve 22 may be formed as a unit with the high-pressure pump 24. For example, that can

Mengensteuerventil 22 a forced openable intake valve of

Be high pressure pump 24.

During operation of the fuel delivery device 10, the prefeed pump 16 conveys fuel from the fuel tank 12 into the low-pressure line 18

Quantity control valve 22, the amount of fuel supplied to a working space of the high-pressure pump 24 by an armature 46 (see Figure 2) of the

Electromagnet 20 from a first to a second position - and vice versa - is moved. The quantity control valve 22 can thus be closed and opened.

Figure 2 shows a partial sectional view (longitudinal section) of

High pressure pump 24 of the fuel delivery device 10 together with the quantity control valve 22 and the electromagnetic actuator 20. The illustrated arrangement comprises a housing 36 in which in the in

Drawing upper portion of the electromagnetic actuator 20, in the middle region of the quantity control valve 22, and in the lower part of a delivery chamber 38 are arranged together with a piston 40 of the high pressure pump 24.

The electromagnetic actuator 20 is arranged in a valve housing 42, and comprises a coil 44, an armature 46, a pole core 48, an armature spring 50, a rest seat 52 and a stroke stop 54. The rest seat 52 represents the first position of the armature 46, and the stroke stop 54 represents the second position of the armature 46. The armature 46 is acted upon by means of a

Coupling element 56 a valve body 58. In the drawing above the Valve body 58, an associated sealing seat 60 is arranged. The sealing seat 60 is part of a pot-shaped housing element 62, which encloses inter alia the valve body 58 and a valve spring 64. Sealing seat 60 and valve body 58 form the inlet valve of the high-pressure pump 24.

The armature 46 is pressed by means of the armature spring 50 in the drawing down against the rest seat 52 in Figure 2, the de-energized state of the electromagnetic actuator. About the

Coupling element 56 is thereby acted upon by the valve body 58 against the force of the valve spring 64, whereby the inlet valve or the

Quantity control valve 22 opens. As a result, a fluidic connection between the low-pressure line 18 and the delivery chamber 38 is produced.

In the energized state of the electromagnetic actuator 20, the armature 46 is magnetically attracted by the pole core 48, whereby the coupling element 56 connected to the armature 46 is moved upward in the drawing. As a result, the valve body 58 can be pressed against the sealing seat 60 by the force of the valve spring 64 with corresponding fluid pressure ratios, and thus close the inlet valve or the quantity control valve 22. This can be done, for example, when the piston 40 in the delivery chamber 38 performs a working movement (in the drawing up), wherein fuel via an open thereby check valve 66 in the

High pressure line 26 can be promoted.

The opening or closing of the quantity control valve 22 takes place in

Depending on several sizes: First, depending on the forces exerted by the armature spring 50 and the valve spring 64 forces. Second, depending on the prevailing in the low pressure line 18 and the delivery chamber 38 fuel pressure. Third, depending on the force of the armature 46, which is essentially determined by a current I currently flowing through the coil 44.

Figure 3 shows a timing diagram of a control of the quantity control valve 22. In the coordinate system shown in the drawing are currents 11 (solid) and 12 (dashed), which via the coil 44 of

electromagnetic actuator 20 flow over a time t applied. Double arrows 68 and 70 or 72 indicate a first phase or a second phase or a third phase of the control of

electromagnetic actuator 20 and thus the coil 44th

The first and second phases beginning at time t0 together cause a pull-in phase of the armature 46, and the third phase beginning at time t1 causes a hold phase of the armature 46. During the pull-in phase, the armature 46 is moved by magnetic force from the rest seat 52 to the armature 46 Stroke stop 54 moves. During the hold phase, the armature 46 is held in position by a generally smaller magnetic force on the stroke stop 54.

A time interval 74 denotes a further phase of the activation of the electromagnetic actuator 20, in which the energization of the coil 44 is switched off. In this case, the current 11 or 12 is reduced comparatively rapidly to zero, so that the armature 46 can fall from the stroke stop 54 back to the rest seat 52.

The course of the current 11, which results in the method according to the invention, will be described below. The current 12 results at a

Method according to the prior art in one by means of thresholds

"current controlled" electromagnetic actuator 20 and is shown for comparison only.

In the first phase of the control, the coil 44 is constantly connected to a

Voltage, for example, a battery voltage of a motor vehicle.

This results in the steep rise of the current 11 shown in the left-hand area of the drawing of FIG.

In the second phase, the voltage is periodically applied to the coil at a (constant) first frequency 76 and a (constant) first duty cycle 78

44 switched. The first frequency 76 is the reciprocal of the period T of the current 11 shown in the drawing of FIG. The first duty cycle 78 is characterized by a relative duty cycle 80 - in which the current 11 increases - and by a relative turn-off duration 82 - in which the current 11 drops. In the third phase, the voltage is periodically switched to the coil 44 at a second frequency (without reference numeral) and at a second duty cycle (without reference numeral). The second frequency and the second duty cycle are also constant during the third phase. In the present case, the second frequency is equal to the first frequency. The second

Duty cycle has a relative to the first duty ratio lower duty cycle 80, so that there is a correspondingly smaller average value of the current 11 during the third phase.

The respective duration of the three phases shown in FIG. 3 as well as the first and the second frequency as well as the first and the second duty cycle are determined using the map 34. This determination is made before the start (time tO) of the drive in dependence on the current level of the voltage, from the current temperature of the coil 44, of the

Cable resistance of a cable by means of which the coil 44 to the

Drive circuit 31 is connected, and in dependence on the current speed of the internal combustion engine. Thus, the course of the current 11 after the time tO - at least for a single switching operation of

Quantity control valve 22 - the result of a control. A regulation by means of the current 11 influencing thresholds does not occur.

The dashed line in the drawing of Figure 3 course of the current 12, which, as mentioned above, a current-controlled control of the coil 44 is approximated by the course of the current 11 satisfactorily. In particular, the sum energies of the drive during the first and the second phase are substantially the same. The same applies to the third phase.

The sum energy for the first and the second phase can be determined for the current 11 and the current 12, respectively, via the following proportional relationships:

The goal is the equality of both energies, that is = w 12

In a further embodiment, not shown, the second frequency is different from the first frequency 76.

Figure 4 shows a simplified flowchart for controlling the

electromagnetic actuator 20. The illustrated method is preferably performed by means of the computer program 32 in the control and / or regulating device 30 of the internal combustion engine. In a first block 84, the illustrated procedure begins, whereby different variables are determined and / or read from a data memory of the control and / or regulating device 30:

- The current speed of the internal combustion engine;

- An amount of fuel to be injected or an equivalent value;

- the amount of battery voltage;

the temperature of the coil 44; and or

the value of the cable resistance of the cable to which the coil 44 is connected.

In addition, other sizes or operating variables of

Quantity control valve 22 and / or the internal combustion engine to be used. In a subsequent second block 86, different drive quantities are determined using the characteristic field 34 on the basis of the variables mentioned above. These driving sizes are:

- the respective durations of the three phases;

- the first and the second frequency; and or

the first and the second duty cycle. These control variables and their value ratio to one another essentially determine the time profile of the current I, as illustrated, for example, as current 11 in FIG.

In a subsequent third block 88, the coil 44 of the electromagnetic actuator 20 is driven using the determined drive quantities. In this case, the control variables ascertained in block 86 can be used for a plurality of successive activations of the coil 44 or switching operations of the quantity control valve 22, or alternatively the actuation variables can be newly determined for each individual switching operation of the quantity control valve 22.

Claims

claims

1 . Method for operating a fuel delivery device (10) of a

Internal combustion engine, in which an electromagnetic actuator (20) of a quantity control valve (22) is switched to set a delivery rate, characterized in that a control of the electromagnetic actuator (20) for moving an armature (46) of the electromagnetic actuator (20) from a first in a second position comprises at least three phases (68, 70, 72), wherein in a first phase (68), a coil (44) of the electromagnetic actuator (20) is continuously switched to a voltage, and wherein in a second phase (70 ), the coil (44) is periodically switched to the first voltage (76) and to a first duty cycle (78) to the voltage, and wherein in a third phase (72) the coil (44) periodically at a second frequency and with a second duty cycle is switched to the voltage.

2. The method according to claim 1, characterized in that a respective duration of the three phases (68, 70, 72) and / or the first frequency (76) and / or the second frequency and / or the first duty cycle (78) and / or the second duty cycle as a function of the voltage and / or a temperature and / or a line resistance and / or a rotational speed of the internal combustion engine can be adjusted.

3. The method according to claim 1 or 2, characterized in that the first and the second phase (68, 70) cause a starting phase of the armature (46), and that the third phase (72) causes a holding phase of the armature (46).

4. The method according to claim 2 or 3, characterized in that the

respective duration of the three phases (68, 70, 72) and / or the first frequency (76) and / or the second frequency and / or the first duty cycle (78) and / or the second duty cycle is determined using at least one characteristic map (34).

5. The method according to at least one of the preceding claims, characterized in that the first frequency (76) is equal to the second frequency.

6. drive circuit (31) for driving an electromagnetic

Actuating device (20) of a volume control valve (22), characterized in that the drive circuit (31) comprises means for performing a control by means of at least three phases (68, 70, 72) according to at least one of the preceding claims.

7. Computer program (32), characterized in that it is programmed to carry out a method according to at least one of the preceding claims.

8. Control and / or regulating device (30) of an internal combustion engine, characterized in that it comprises a memory on which a

Computer program (32) according to claim 7 is stored.