CN104373662B - The method and apparatus controlling magnetic valve - Google Patents

Abstract

The invention provides a method for controlling a solenoid valve, which comprises the following steps in the opening stage of the solenoid valve: applying an opening voltage whose voltage value is higher than the normal power supply voltage to quickly open the solenoid valve, and checking whether two predetermined conditions are met at the same time, The turn-on voltage is turned off immediately if one condition is met, wherein the first condition is that there is current flowing through the solenoid valve, and the current exceeds a peak current threshold, and the second condition is selected as a condition that does not occur under normal operating conditions. Further, the second condition is that after the turn-on voltage is applied, the voltage drop value of the high-voltage source providing the turn-on voltage is greater than a voltage threshold. The present invention also provides a device for realizing the above method. The advantage of the present invention is that even if a solenoid valve has a problem, it can ensure that only a small portion of energy is consumed in the energy storage capacitor of the high-voltage source, thereby not affecting the normal driving of other solenoid valves. Therefore, the control of the solenoid valve will be more reliable.

Description

Method and device for controlling a solenoid valve

technical field

The invention relates to a high-pressure common rail fuel injection system, in particular to a method and device for controlling an electromagnetic valve in the high-pressure common rail fuel injection system.

Background technique

In the high-pressure common rail fuel injection system, as shown in Figure 1, in order to speed up the opening speed of the solenoid valve, it is usually necessary to apply a higher voltage in the initial stage of solenoid valve driving, so that a large peak driving force is immediately generated in the solenoid valve current (I _peak ). The high-voltage voltage usually comes from the energy storage capacitor, and the energy in the energy storage capacitor is usually recharged to the target high voltage value by using a DC/DC converter during the idle time of each solenoid valve drive. When the solenoid valve is stably opened, a small current (maintaining current I _hold ) can be used to maintain the conduction state of the solenoid valve. At this time, it only needs to take power from a constant power source, such as a battery on a car. In order to realize the "peak-hold" driving current waveform of the solenoid valve, its control method and device are the key.

Chinese patent CN101477870A discloses a method and device for generating driving current of a solenoid valve. In the method for generating the solenoid valve drive current waveform described in CN101477870A, when the solenoid valve drive current rises above the peak drive current, the signal processing circuit sends a low-level control signal to the high-end drive circuit, so the high-end power triode Close, that is, to turn off the application action of high voltage.

Under normal operating conditions, the method described in CN101477870A has no problem. However, under abnormal operating conditions, the method described in CN101477870A has problems. For example, after a problem occurs in the solenoid valve, its parameters become larger. In order to achieve a predetermined peak driving current, more energy will inevitably be consumed from the energy storage capacitor. When the engine is running at high speed, the interval between two solenoid valve actuations is very short. If the energy consumption in the energy storage capacitor is too much during the last solenoid valve actuation, the energy storage capacitor may not replenish the target high voltage value before the next solenoid valve actuation. This will affect the normal driving of the solenoid valve next time, and even cause a vicious circle, so that the energy consumption in the energy storage capacitor is more, and all the solenoid valves cannot be driven normally.

Contents of the invention

The primary purpose of the present invention is to provide a reliable solenoid valve control method, which can ensure that only a small portion of energy is consumed in the energy storage capacitor even after a certain solenoid valve has a problem, thereby not affecting the normal driving of other solenoid valves.

The second object of the present invention is to provide a device for controlling a solenoid valve that realizes the above method. The technical scheme adopted in the present invention is:

A method for controlling a solenoid valve, comprising the steps of:

Apply an opening voltage with a voltage value higher than the normal power supply voltage to quickly open the solenoid valve, and check whether two predetermined conditions are met at the same time. If one of the conditions is met, the opening voltage is immediately turned off. The first condition is that there is current flow. through the solenoid valve, and the current exceeds a peak current threshold, the second condition is selected as a condition that does not occur under normal operating conditions.

Further, the second condition is that after the turn-on voltage is applied, the voltage drop value of the high-voltage source providing the turn-on voltage is greater than a voltage threshold.

Further, the selected voltage threshold value is greater than the voltage drop value in the high voltage source during the opening phase of the solenoid valve under normal operation conditions.

Further, a high-voltage energy storage capacitor is used as a high-voltage source for providing a turn-on voltage; a storage battery is used as a constant power supply.

A device for controlling a solenoid valve, comprising:

The high-voltage source is connected to the current inflow end of the high-voltage switch and the input end of the high-voltage source voltage sampling and threshold comparison circuit; the normal power supply is connected to the current inflow end of the normal power switch; One end of the valve and the other end of the solenoid valve are connected to the input end of the solenoid valve current sampling and threshold value comparison circuit; the output ends of the high voltage source voltage sampling and threshold value comparison circuit and the solenoid valve current sampling and threshold value comparison circuit are connected to control high voltage opening Or close the logic circuit, control the high voltage to open or close the output terminal of the logic circuit to the control terminal of the high voltage switch;

In the opening stage of the solenoid valve, when the solenoid valve current sampling and threshold comparison circuit detects that the current flowing through the solenoid valve exceeds a peak current threshold, or when the high voltage source voltage sampling and threshold comparison circuit detects the voltage drop value of the high voltage source When the voltage is greater than a threshold value, the high voltage is controlled to open or close the logic circuit to turn off the high voltage switch, thereby immediately closing the opening voltage.

Further, the high voltage switch control logic circuit includes an AND gate G3.

The solenoid valve current sampling and threshold value comparison circuit includes resistors R11, R12, R13, R14 and R15, and a comparator U2; the other end of the solenoid valve is the current outflow terminal connected to one end of the resistor R14 and one end of the resistor R13; the other end of the resistor R14 Grounding, the other end of the resistor R13 is connected to the inverting input of the comparator U2; the non-inverting input of the comparator U2 is connected to one end of the resistors R11 and R12, the other end of the resistor R11 is connected to the positive voltage VCC, and the other end of the resistor R12 is grounded; The output terminal of the device U2 is connected to one end of the resistor R15 and an input end of the AND gate G3; the other end of the resistor R15 is connected to the positive voltage VCC;

The high-voltage source voltage sampling and threshold comparison circuit includes resistors R1, R2, R3, R4 and R5; the high-voltage source 100 is connected to one end of resistor R1, the other end of resistor R1 is connected to one end of resistor R2 and the non-inverting input end of comparator U1, and the resistor The other end of R2 is grounded; the inverting input terminal of comparator U1 is connected to one end of resistors R3 and R4, the other end of resistor R3 is connected to positive voltage VCC, and the other end of resistor R4 is grounded; the output terminal of comparator U1 is connected to one end of resistor R5 And the other input end of the AND gate G3; the other end of the resistor R5 is connected to the positive voltage VCC;

The output terminal of the AND gate G3 is connected to the control terminal of the high voltage switch.

The advantage of the present invention is that even if a solenoid valve has a problem, it can ensure that only a small portion of energy is consumed in the energy storage capacitor, thereby not affecting the normal driving of other solenoid valves. Therefore, the control of the solenoid valve will be more reliable.

Description of drawings

Figure 1 is a schematic diagram of the driving current waveform of the solenoid valve.

Fig. 2a is a schematic diagram of a device for controlling a solenoid valve of the present invention.

Fig. 2b is a detailed schematic diagram of part of the circuit of the device for controlling the solenoid valve of the present invention.

Fig. 3 is a flow chart of the method for controlling the solenoid valve of the present invention.

detailed description

The present invention will be further described below in conjunction with specific drawings and embodiments.

FIG. 1 shows a driving current waveform of a solenoid valve mentioned in the background information of the present invention. T1 is the rapid opening stage of the solenoid valve. In this stage, electricity needs to be taken from a high-voltage source, so that the current flowing through the solenoid valve reaches a peak current (I _peak ) instantaneously. I _peak is the threshold value of the peak current, and the high voltage is turned off immediately after reaching switch, the driving current begins to drop; T2 is the fully open stage of the solenoid valve, in which the power is usually drawn from a constant power supply (such as a battery), and only a small current (holding current I _hold ) is needed to maintain the solenoid valve. The conduction state of the valve.

Figure 2a shows a device for controlling a solenoid valve provided by the present invention. Among them, 100 is a high-voltage source, which can usually use a high-voltage energy storage capacitor; 110 is a constant power supply, which can use a battery; 120 is a high-voltage switch, which can use a power MOS tube or triode; 130 is a constant power switch, which can use a power MOS tube Or triode; 140 is a solenoid valve, 150 is a high voltage source voltage sampling and threshold value comparison circuit, 160 is a solenoid valve current sampling and threshold value comparison circuit, 170 is a logic circuit for controlling high voltage on or off.

Since the high voltage source 100 provides the opening voltage for the solenoid valve opening stage, the voltage of the energy storage capacitor serving as the high voltage source 100 after sufficient energy storage is higher than the voltage provided by the battery serving as the constant power supply 110 . The high pressure source 100 provides the high pressure required for the solenoid valve opening phase.

The electrical connections are as follows: the high voltage source 100 is connected to the current inflow end of the high voltage switch 120 and the input end of the high voltage source voltage sampling and threshold comparison circuit 150; the normal power supply 110 is connected to the current inflow end of the normal power switch 130; the high voltage switch 120 and The current outflow end of the constant power supply switch 130 is connected to one end of the solenoid valve 140, and the other end of the solenoid valve 140 is connected to the input end of the solenoid valve current sampling and threshold value comparison circuit 160; the high voltage source voltage sampling and threshold value comparison circuit 150 and the electromagnetic valve The output terminals of the valve current sampling and threshold comparison circuit 160 are both connected to the logic circuit 170 for controlling the high voltage on or off, and the output terminals of the logic circuit 170 for controlling the high voltage on or off are connected to the control terminal of the high voltage switch 120 . In the opening stage of the solenoid valve, when the solenoid valve current sampling and threshold comparison circuit 160 detects that the current flowing through the solenoid valve 140 exceeds a peak current threshold, or when the high voltage source voltage sampling and threshold comparison circuit 150 detects that the high voltage source 100 When the voltage drop value is greater than a voltage threshold value, the logic circuit 170 is controlled to turn off the high voltage switch 120 to turn off the high voltage switch 120, so as to immediately turn off the turn-on voltage.

The control terminal of the constant power switch 130 is connected to another logic circuit, but it is omitted because it is not within the scope of the discussion of the present invention. In this embodiment, both the high voltage switch 120 and the normal power switch 130 use power MOS transistors, so the control terminal is the gate, the current inflow terminal is the drain, and the current outflow terminal is the source.

In the rapid opening stage of the solenoid valve, the high-voltage switch 120 is turned on, and the constant power switch 130 is turned off, that is, power is taken from the high-voltage source 100 and current flows through the solenoid valve 140 . At this time, on the one hand, the solenoid valve current sampling and threshold comparison circuit 160 performs real-time judgment; on the other hand, the high voltage source voltage sampling and threshold comparison circuit 150 also performs real-time judgment. As long as one of the two satisfies the judgment condition, the high-voltage switch control logic circuit 170 will function to turn off the high-voltage switch 120 .

The first condition is that there is current flowing through the solenoid valve 140, and the current exceeds a peak current threshold I _peak ; the second condition is that after the opening voltage is applied, the voltage drop value of the high voltage source 100 that provides the opening voltage is greater than a voltage threshold . For this purpose, a specific circuit as shown in Fig. 2b is used to realize the conditional judgment.

The high voltage switch control logic circuit 170 includes an AND gate G3.

Solenoid valve current sampling and threshold comparison circuit 160 includes resistors R11, R12, R13, R14 and R15, comparator U2; the other end of solenoid valve 140 is the current outflow terminal connected to one end of resistor R14 and one end of resistor R13; The other end of the resistor R13 is connected to the inverting input of the comparator U2; the non-inverting input of the comparator U2 is connected to one end of the resistors R11 and R12, the other end of the resistor R11 is connected to the positive voltage VCC, and the other end of the resistor R12 is grounded ; The output terminal of the comparator U2 is connected to one end of the resistor R15 and an input end of the AND gate G3; the other end of the resistor R15 is connected to the positive voltage VCC.

Wherein, the comparator U2 is an operational amplifier, and the resistor R14 is a sampling resistor, which converts the current flowing through the solenoid valve 140 into a voltage.

The high-voltage source voltage sampling and threshold comparison circuit 150 includes resistors R1, R2, R3, R4, and R5; the high-voltage source 100 is connected to one end of the resistor R1, and the other end of the resistor R1 is connected to one end of the resistor R2 and the non-inverting input end of the comparator U1. The other end of the resistor R2 is grounded; the inverting input terminal of the comparator U1 is connected to one end of the resistors R3 and R4, the other end of the resistor R3 is connected to the positive voltage VCC, and the other end of the resistor R4 is grounded; the output terminal of the comparator U1 is connected to the resistor R5 One end and the other input end of the AND gate G3; the other end of the resistor R5 is connected to the positive voltage VCC.

The output terminal of the AND gate G3 is connected to the control terminal of the high voltage switch 120 .

Wherein, the comparator U1 adopts an operational amplifier. The purpose of using resistors R1 and R2 to divide the voltage is to make the voltage of the higher high voltage source 100 match the voltage input range of the comparator U1. Resistors R3 and R4 divide the voltage to set a suitable comparison reference voltage at the inverting input of U1.

In the opening stage of the solenoid valve, when the voltage drop value of the high voltage source 100 is greater than a voltage threshold value, the voltage of the non-inverting input terminal of the comparator U1 will be lower than the voltage of the inverting input terminal, the comparator U1 outputs a low level, and the AND gate G3 It also outputs a low level to turn off the high voltage switch 120 .

When the current flowing through the solenoid valve 140 exceeds a peak current threshold, the voltage of the inverting input terminal of the comparator U2 is higher than the voltage of the non-inverting input terminal, the comparator U2 outputs a low level, and the AND gate G3 also outputs a low level Ping, to turn off the high voltage switch 120 .

Fig. 3 shows the specific flow of the method for controlling the solenoid valve provided by the present invention. in,

S1 is the preparatory stage for the start of solenoid valve actuation, and its occurrence time depends on the state of the engine;

S2 is the stage of applying high voltage (that is, the opening voltage). At this time, the high-voltage switch 120 is turned on, and the normal power switch 130 is turned off, that is, power is taken from the high-voltage source 100, and a large current (opening current) is generated in the solenoid valve 140;

S3 is the first condition judging process, and the solenoid valve current sampling and threshold comparison circuit 160 provides a judging result. If I>I _peak , it means that the current flowing through the solenoid valve reaches the peak current threshold value, then enter S5 to close the high voltage, at this time the high voltage switch 120 is closed, and the normal power supply switch 130 is turned on, that is, power is taken from the normal power supply 110; otherwise Entering S4, S4 is the second condition judgment process, the high voltage source voltage sampling and threshold comparison circuit 150 provides the judgment result. If ΔU>U _max , it means that the high voltage drop value in the energy storage capacitor as the high voltage source 100 exceeds the threshold value, then enter S5 to turn off the high voltage, and the high voltage switch 120 is turned off. Otherwise, repeat the judging process of the two conditions.

Under normal operating conditions, usually only the solenoid valve current sampling and threshold value comparison circuit 160 meets the conditions; but in abnormal operating conditions, the high-voltage source voltage sampling and threshold value comparison circuit 150 first meets the conditions, so that it can be avoided. After the parameter becomes larger, too much energy is consumed in the energy storage capacitor to realize the rated peak current I _peak , thereby ensuring the normal control of other solenoid valves under the high engine speed condition.

Claims (3)

1. A device for controlling a solenoid valve, characterized in that it comprises: The high voltage source (100) is connected to the current inflow terminal of the high voltage switch (120) and the input terminal of the high voltage source voltage sampling and threshold comparison circuit (150); the normal power supply (110) is connected to the current inflow terminal of the normal power switch (130) The current outflow ends of the high-voltage switch (120) and the constant power supply switch (130) are all connected to one end of the solenoid valve (140), and the other end of the solenoid valve (140) is connected to the solenoid valve current sampling and threshold comparison circuit (160) Input terminal; the output terminals of the high-voltage source voltage sampling and threshold value comparison circuit (150) and the solenoid valve current sampling and threshold value comparison circuit (160) are all connected to the control high-voltage open or close logic circuit (170), and the control high-voltage open or close logic The output terminal of the circuit (170) is connected to the control terminal of the high voltage switch (120); In the opening stage of the solenoid valve, when the solenoid valve current sampling and threshold comparison circuit (160) detects that the current flowing through the solenoid valve (140) exceeds a peak current threshold, or when the high voltage source voltage sampling and threshold comparison circuit (150 ) when detecting that the voltage drop of the high voltage source (100) is greater than a voltage threshold, control the high voltage on or off logic circuit (170) to turn off the high voltage switch (120), thereby immediately turning off the on voltage. 2. The device for controlling the solenoid valve as claimed in claim 1, characterized in that: Controlling the high voltage to open or close the logic circuit (170) includes an AND gate G3; Electromagnetic valve current sampling and threshold value comparison circuit (160) comprises resistance R11, R12, R13, R14 and R15, comparator U2; The other end of the resistor R14 is grounded, the other end of the resistor R13 is connected to the inverting input of the comparator U2; the non-inverting input of the comparator U2 is connected to one end of the resistors R11 and R12, the other end of the resistor R11 is connected to the positive voltage VCC, and the resistor R12 The other end of the resistor is grounded; the output terminal of the comparator U2 is connected to one end of the resistor R15 and an input end of the AND gate G3; the other end of the resistor R15 is connected to the positive voltage VCC; The high-voltage source voltage sampling and threshold comparison circuit (150) includes resistors R1, R2, R3, R4 and R5; the high-voltage source (100) is connected to one end of the resistor R1, and the other end of the resistor R1 is connected to one end of the resistor R2 and the comparator U1 The non-inverting input terminal, the other end of the resistor R2 is grounded; the inverting input terminal of the comparator U1 is connected to one end of the resistors R3 and R4, the other end of the resistor R3 is connected to the positive voltage VCC, and the other end of the resistor R4 is grounded; the output terminal of the comparator U1 Connect one end of the resistor R5 and the other input end of the AND gate G3; the other end of the resistor R5 is connected to the positive voltage VCC; The output terminal of the AND gate G3 is connected to the control terminal of the high voltage switch (120). 3. The device for controlling the solenoid valve as claimed in claim 1 or 2, characterized in that: Both the high-voltage switch (120) and the constant power switch (130) use power MOS tubes or triodes.