阅读说明：本技术 用于控制高压燃料喷射器的控制方法 (Control method for controlling a high-pressure fuel injector ) 是由 T·巴伏瓦 于 2020-03-23 设计创作，主要内容包括：一种用于控制燃料喷射器的控制方法,该燃料喷射器设有用于致动针的螺线管和用于将所述针返回到关闭位置的回位弹簧,所述针用于打开喷射器,螺线管由控制装置供应电流,控制装置包括连接到第一晶体管的漏极的第一电位,第一晶体管的源极连接到第一二极管的阳极,第一二极管的阴极连接到第二二极管的阴极、螺线管的第一连接器、以及第二晶体管的源极,第二晶体管的漏极连接到第二电位,第二二极管的阳极接地,第二电位通过电容接地并且连接到第三二极管的阴极,第三二极管的阳极连接到螺线管的第二连接器和第三晶体管的漏极,第三晶体管的源极接地。(A control method for controlling a fuel injector provided with a solenoid for actuating a needle for opening the injector and a return spring for returning the needle to a closed position, the solenoid being supplied with current by a control device comprising a first potential connected to a drain of a first transistor, a source of the first transistor being connected to an anode of a first diode, a cathode of the first diode being connected to a cathode of a second diode, a first connector of the solenoid, and a source of a second transistor, a drain of the second transistor being connected to a second potential, an anode of the second diode being connected to ground, the second potential being connected to ground via a capacitor and to a cathode of a third diode, an anode of the third diode being connected to a second connector of the solenoid and to a drain of a third transistor, a source of the third transistor being connected to ground.)

1. A control method for controlling a high-pressure fuel injector for an internal combustion engine of a motor vehicle, the injector being provided with a solenoid for actuating a needle for opening the injector and a return spring for returning the needle to a closed position, the solenoid of the fuel injector being supplied with current by a control means comprising a first potential connected to the drain of a first transistor (T1), the source of the first transistor (T1) being connected to the anode of a first diode (D1), the cathode of the first diode (D1) being connected to the cathode of a second diode (D2), a first connector of the solenoid of the injector, and the source of a second power transistor (T2), the drain of the second transistor (T2) being connected to a second potential, the anode of the second diode (D2) being connected to ground, the second potential is connected to ground via a capacitance (C), the second potential being further connected to the cathode of a third diode, the anode of the third diode being connected to the second connector of the solenoid of the injector and to the drain of a third transistor (T3), the source of the third transistor (T3) being connected to ground via a resistor,

characterized in that the control means further comprise an additional diode connected by its anode to the source of the second transistor (T2) and by its cathode to the first connector of the ejector,

the control method comprises the following steps:

determining whether the second potential is below a potential threshold that allows generation of a current for opening the needle of the injector,

if this is the case, determining whether the first potential is higher than the second potential,

if this is the case, it is determined whether injection is not required,

if this is the case, the transistors of the control means are first controlled to be in a first state in which the first transistor (T1) is controlled to be on and the second transistor (T2) and the third transistor (T3) are controlled to be off, and then, after detecting that the solenoid charging current flowing through the first transistor (T1) is larger than a reference current, the transistors (T1, T2, T3) are controlled to be in a second state in which the first transistor (T1), the second transistor (T2) and the third transistor (T3) are controlled to be off to obtain a charge transfer effect between the first potential and the second potential which are input,

wait a predetermined duration to allow the solenoid to discharge,

determining whether the second potential is below a potential threshold that allows generation of a current for opening the needle of the injector,

if this is the case, the method returns to charging the solenoid of the injector.

2. A control method according to the preceding claim, wherein, when it has been determined that injection is required, it is determined whether an adjustment of the current circulating in the solenoid of the injector is being performed,

if this is the case, when the regulated current needs to be reduced, the first transistor (T1) is controlled to turn off to discharge the solenoid of the injector by passing current through the second diode (D2) and the third diode, while the second transistor (T2) and the third transistor (T3) are controlled to turn off.

3. A control method according to any one of the preceding claims, wherein said first potential is equal to the potential of a battery powering the motor vehicle.

Technical Field

The technical field of the invention is the control of high-pressure fuel injectors, more specifically the generation of a control voltage for such injectors.

Background

The high pressure fuel injector includes a needle driven by a solenoid and a return spring.

To trigger fuel injection, a needle is raised to open an orifice of an injector and place a fuel inlet (e.g., an injection common rail) in communication with a combustion chamber. To this end, an electric current is caused to flow in the solenoid, the electric current having a sufficient strength to generate a magnetic force greater than a restoring force of the spring.

To stop the injection, the needle must be pushed back into the injector in order to close the orifice of the injector. To achieve this, the flow of current through the solenoid is interrupted. The magnetic force is interrupted and the return spring returns the needle into its rest position, closing the orifice of the injector.

In the rest of the description, the injector solenoid or injector in the supply case and in the control case are considered in a non-differentiated manner.

More precisely, the opening of the high-pressure fuel injector requires a surge current or PEAK current (denoted PEAK in the rest of the description) to open, allowing the needle to be raised up to the open position. Once the open position is reached, the opening is maintained by a low intensity current having a first intensity and a second intensity (represented in the remainder of this description by HOLD1 and HOLD2, respectively). Fig. 1 shows these different currents during the fuel injection phase.

The generation of PEAK current involves current regulation based on the potential Vboost.

The generation of HOLD1 and HOLD2 currents involves the regulation of the currents. The HOLD1 and HOLD2 currents may be obtained based on the battery voltage Vbat, taking into account its strength and its regulation.

When the PEAK current has been generated, the value of the potential Vboost decreases, so that it is necessary to raise it before the PEAK current is generated again.

To achieve this, the control means is typically controlled so as to generate a current from the battery to the potential Vboost. This mechanism assumes that the battery voltage Vbat is lower than the potential Vboost.

However, in some vehicles, the battery has a voltage of 48V, which may vary over a large range of values. Therefore, the battery voltage Vbat may be higher than the potential Vboost. It is therefore necessary to use a voltage-reducing circuit, also called a "circuit buck", to regenerate the potential Vboost.

In the case of 48V-based automotive batteries powering fuel injectors, the voltage step-down circuitry required is particularly large and expensive.

There is a need for control of a high pressure fuel injector that does not require a voltage reduction circuit separate from the control device in order to reduce the volume and cost of fuel injector control.

There is no control device for controlling the high-pressure fuel injector as follows: the control device does not require a voltage step-down circuit separate from the control device.

The above technical problems still remain.

Disclosure of Invention

The subject of the invention is a control method for controlling a high-pressure fuel injector for an internal combustion engine of a motor vehicle, the injector being provided with a solenoid for actuating a needle for opening the injector and with a return spring for returning the needle to a closed position, the solenoid of the fuel injector being supplied with current by a control device comprising a first potential connected to the drain of a first transistor, the source of which is connected to the anode of a first diode, the cathode of which is connected to the cathode of a second diode, the first connector of the solenoid of the injector and the source of a second power transistor, the drain of which is connected to a second potential, the anode of which is grounded, the second potential being grounded via a capacitor, the second potential also being connected to the cathode of a third diode, the anode of the third diode is connected to the second connector of the solenoid of the injector and to the drain of the third transistor, the source of which is connected to ground via a resistor.

The control means further comprise an additional diode connected by its anode to the source of the second transistor and by its cathode to the first connector of the ejector.

The control method comprises the following steps:

determining whether the second potential is below a potential threshold that allows generation of a current for opening a needle of the injector,

if this is the case, it is determined whether the first potential is higher than the second potential,

if this is the case, it is determined whether injection is not required,

if this is the case, the transistors of the control means are first controlled to be in a first state in which the first transistor is controlled to be on and the second transistor and the third transistor are controlled to be off, and then, after detecting that the solenoid charging current flowing through the first transistor is larger than the reference current, the transistors are controlled to be in a second state in which the first transistor, the second transistor and the third transistor are controlled to be off to obtain a charge transfer effect between the input first potential and the second potential,

wait a predetermined duration to allow the solenoid to discharge,

determining whether the second potential is below a potential threshold that allows generation of a current for opening a needle of the injector,

if this is the case, the method returns to charging the solenoid of the injector.

When it has been determined that injection is required, it can be determined whether regulation of the current circulating in the solenoid of the injector is being performed,

if this is the case, when the regulated current needs to be reduced, the first transistor is controlled to be off to discharge the solenoid of the injector by passing current through the second and third diodes, while the second and third transistors are controlled to be off.

The first potential may be equal to a potential of a battery that powers the motor vehicle.

Drawings

Other objects, features and advantages of the present invention will become apparent from a reading of the following description, given purely by way of non-limiting example and with reference to the accompanying drawings, in which:

figure 1 shows the main variations of the current circulating in the injector solenoid during injection,

figure 2 shows the main components of the voltage step-down circuit,

figure 3 shows the main elements of a control device for controlling an injector,

FIG. 4 shows the main elements of a control device for controlling an injector, which is modified when the second potential is higher than the first potential well, and

fig. 5 shows the main steps of a control method for controlling an injector.

Detailed Description

Fig. 2 shows a step-down circuit for regenerating the potential Vboost.

The voltage step-down circuit 1 comprises a first input E1, a second input E2, a first output S1 and a second output S2.

The transistor T is connected by its drain to the first input E1 and by its source to one end of the inductance L and to the cathode of the input diode De.

The other end of the inductor L is connected to the anode of the output diode Ds. A cathode of the output diode Ds is connected to the first output S1 and one end of the capacitor Cs, and the other end of the capacitor Cs is connected to the second input E2, the second output S2, and an anode of the input diode De.

The input voltage Ve is applied between the two inputs E1, E2, while the transistor T is controlled to turn off if the output voltage Vs is lower than its nominal voltage. The current in the inductor L increases until its charge value.

When the transistor T is controlled to be on, the inductor L is discharged through the input diode De and the two outputs S1, S2. The output voltage Vs is lower than the previously applied input voltage Ve so that a continuous current required by the load can be provided at the output.

It should be noted that the capacitor Cs is charged during the charging and discharging of the inductance L. Then, the capacitor Cs is discharged when additional current is drawn at the output. The capacitor Cs makes it possible to smooth the output voltage.

The transistor T switches fast enough to be able to quickly charge the capacitance at the output to supply current to the load.

In fig. 3, the structure of a control device 2 for controlling a high-pressure fuel injector can be seen.

The control means comprise a first potential Vbat, which is normally connected to the battery. The first potential Vbat is connected to the drain of the first power transistor T1. A source of the first power transistor T1 is connected to an anode of the first diode D1. A cathode of the first diode D1 is connected to a cathode of the second diode D2, a first connector of the injector INJ, and a source of the second power transistor T2. The drain of the second power transistor T2 is connected to the second potential Vboost. The second potential Vboost is normally connected to the booster circuit 1, as shown in fig. 2.

The anode of the second diode D2 is grounded.

The second potential Vboost is grounded via a capacitor C.

The second potential Vboost is also connected to the cathode of the third diode D3, and the anode of the third diode D3 is connected to the second connector of the injector INJ and the drain of the third power transistor T3. The source of the third power transistor T3 is connected to ground through a resistor R.

The control means further comprise means for measuring the first potential Vbat, means for measuring the second potential Vboost and means for measuring the current through the resistor R.

Controlling the three transistors T1, T2, T3 makes it possible to generate and regulate different currents which supply the injector INJ.

In particular, if the first transistor T1 is controlled to be off, and the second transistor T2 and the third transistor T3 are controlled to be on, a current flows from the second potential Vboost through the injector INJ and the resistor R to the ground.

The obtained current then corresponds to the PEAK current. This generation of current eliminates or greatly reduces most of the second potential Vboost. Then, it is necessary to raise the potential of the second potential Vboost back to a predetermined level that allows the PEAK current to be generated.

If the first and second transistors T1 and T2 are controlled to be turned off and the third transistor T3 is controlled to be turned on, current flows through the second diode D2, the injector INJ, and the resistor R to the ground.

The current intensity flowing in injector INJ is then reduced to HOLD1 current, and then HOLD1 current is adjusted.

A similar mechanism is employed to adjust the intensity when changing from HOLD1 current to HOLD2 current, then HOLD2 current is adjusted.

If the first transistor T1 and the third transistor T3 are controlled to be turned on and the second transistor T2 is controlled to be turned off, a current flows from the first potential Vbat to the ground through the first diode D1, the injector INJ, and the resistor R.

The current intensity circulating in the injector INJ then increases to HOLD1 current. As described above, a new phase for reducing the current is then started.

A similar mechanism is employed to increase the intensity when the current intensity is adjusted to be near a particular value (e.g., near HOLD 2).

If the first transistor T1, the second transistor T2, and the third transistor T3 are controlled to be off, a current flows through the second diode D2, the injector INJ, the third diode D3, the second potential Vboost, and the capacitor C to the ground.

The intensity of the current flowing in the injector INJ then rapidly decreases so that zero intensity can be reached and the opening of the injector is cut off and the current changes from HOLD2 to zero intensity.

The inventors have noted that the structure of the control device 2 for controlling the injector includes elements common to the structure of the step-down circuit shown in fig. 2.

It can be seen that the transistor T of fig. 2 corresponds to the first transistor T1 of fig. 3, the input diode De of fig. 2 corresponds to the second diode D2 of fig. 3, the output diode Ds of fig. 2 corresponds to the third diode D3 of fig. 3, the capacitance Cs of fig. 2 corresponds to the capacitor C of fig. 3, and the inductance L corresponds to the solenoid of the injector INJ through which current flows.

The control means may be used so as to raise the second potential Vboost to a potential required to obtain the peak current based on a higher battery voltage than the potential required to obtain the peak current.

For this reason, when the inductance of the injector INJ is discharged to a zero value corresponding to turning off the injector, the first transistor T1 is controlled to be turned on to charge the injector INJ, while the second transistor T2 and the third transistor T3 are controlled to be turned off.

Thus, a current is generated so that the potential of the second potential Vboost can be raised.

The discharge of the inductance may be achieved by controlling the intended operation of the device, in particular by controlling the first transistor T1 and the second transistor T2 to be turned off and the third transistor T3 to be turned off.

A reduction of the injector charge is thus obtained, resulting in a topology similar to a step-down circuit.

However, when the potential Vbat is higher than the potential Vboost, when the first transistor T1 is controlled to be on, a reverse current may flow through the second transistor T2 because this has the effect of increasing the potential Vboost above the operating voltage of the second transistor T2. To avoid such a disadvantage, an additional diode Dadd is added to prevent a current from flowing from the first potential Vbat to the second potential Vboost through the second transistor T2.

The additional diode Dadd must be arranged such that its cathode is connected to the cathode of the first diode D1, the cathode of the second diode D2 and the injector INJ, while its anode is connected to the source of the second transistor T2. Figure 4 shows an improved control device comprising an additional diode.

The control device of the injector exchanges with the electronic control unit the commands for switching the transistors T1, T2, T3 and transmits the values of the measured current and potential. The electronic control unit is thus able to determine the current injector control phase from the commands received from the engine control in combination with the variation of the current circulating in the injector shown in fig. 1.

Therefore, the control method for controlling the injector is applicable to the control device for controlling the injector and the electronic control unit thereof.

In fig. 5, it can be seen that the control method for controlling an injector comprises a first STEP1 during which the value of the second potential is determined, and then it is determined whether the second potential is below a predetermined potential threshold that allows the generation of a PEAK current for opening the needle of the injector.

If this is not the case, the second potential is already at the level required for generating the PEAK current. The method then returns to the first STEP 1.

If this is the case, the method continues to a second STEP2, during which the value of the second potential is determined, and then it is determined whether the first potential Vbat is higher than the second potential Vboost.

If this is not the case, the method returns to the first STEP 1.

If this is the case, the method continues to a third STEP STEP3 during which it is determined whether injection is not required.

If this is the case, the method continues to a third STEP4, during which the transistor is first controlled to be in a first state of the control means during a first sub-STEP SS1, in which the first transistor T1 is controlled to be on and the second transistor T2 and the third transistor T3 are controlled to be off, and during a second sub-STEP SS2, after detecting that the inductor charging current flowing through the first transistor T1 is greater than the reference current, the transistor is controlled to be in a second state, in which the first transistor T1, the second transistor T2 and the third transistor T3 are controlled to be off. The method then returns to the first STEP 1.

In the first state, the inductor of the injector is charged with a reference current, supplied by the first potential Vbat, that is less than the injector activation current, in a manner similar to the charging of the voltage-reducing circuit.

In the second state, the inductance of the injector is released into the second potential Vboost.

During the third substep SS3, a predetermined duration is waited to allow the solenoid to discharge. It should be noted that the waiting time is equal to a fixed value, which allows defining a frequency equal to the frequency of the booster circuit.

During a fourth sub-step SS4, it is determined whether the second potential is below a potential threshold that allows the generation of a current for opening the needle of the injector,

if this is the case, the method returns to charging the solenoid of the injector at step SS 1.

If this is not the case, the method returns to STEP 1.

If, at the third STEP3, it has been determined that injection is required, the method continues to a fourth STEP5, during which, in a third sub-STEP SS5, it is determined whether a regulation of the current circulating in the injector is being performed.

If this is not the case, the method returns to the first STEP 1.

If this is the case, during the fourth substep SS6, it is determined when the regulated current needs to be reduced. When this is the case, the first transistor T1 is controlled to be turned off so as to discharge the injector INJ into the second potential, while the second transistor T2 and the third transistor T3 are controlled to be turned off. The method then returns to the first STEP 1.

Once the current circulating in the injector is regulated, it is possible to recover a portion of the energy used to discharge the injector, raising the second potential towards a predetermined value, while the battery voltage is higher than the second potential.

The control method allows a step-down circuit to be formed using components of the control device so as to raise the second potential based on the battery voltage higher than the voltage of the second potential. If an injection is being performed, the energy that must be supplied to the injector is reused in order to regulate its current to be at the set value, in particular HOLD1 and HOLD 2. If no injection is required, the control device is controlled so as to be able to charge the solenoid of the injector in the form of a step-down circuit towards the second potential and then discharge it conventionally.

The structure of the control device can thus be used for all operating phases of the injector.