Injector failure detection device

Abstract

To provide an injector failure detection device capable of detecting a failure of an injector drive circuit more accurately than before.SOLUTION: An injector failure detection device for detecting a failure of an injector drive circuit based on a state quantity of the injector drive circuit includes: a setting unit for setting a practical setting value based on a load characteristic of the injector drive circuit; and a failure detection unit for detecting the failure of the injector drive circuit based on the practical setting value and the state quantity.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an injector failure detection device. [Background technology]

[0002] The following Patent Document 1 discloses an injector fault detection device for a solenoid valve that can perform highly accurate diagnosis even for solenoid valves with slow plunger operation. This injector fault detection device supplies a rectangular diagnostic voltage different from the operating voltage for driving the solenoid valve, calculates the current change rate within the detection time of the current waveform, and if the current change rate exceeds a set speed two or more times, determines that there is a concave portion in the current waveform. If this is repeated twice and it is determined that there is a concave portion X both times, it diagnoses that the solenoid valve is normal. In addition, by setting the detection time of the current waveform and the set speed according to the operating environment such as oil temperature, the accuracy of the fault diagnosis is improved and the time required for diagnosis is shortened. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-311455 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned background art, the set speed used in fault diagnosis of the solenoid valve is a fixed value. Because there is a certain degree of variation in the drive device that drives the solenoid valve and the solenoid valve driven by the drive device, if the set speed is a fixed value, there is a risk that a fault in the solenoid valve cannot be accurately detected.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide an injector failure detection device that can detect a failure in an injector drive circuit more accurately than conventional devices. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention employs, as a first solution relating to an injector fault detection device, a means for detecting a fault in an injector drive circuit based on a state quantity of the injector drive circuit, comprising: a setting unit that sets a practical set value based on a load characteristic of the injector drive circuit; and a fault detection unit that performs the fault detection based on the practical set value and the state quantity.

[0007] The present invention provides a second solution related to the injector failure detection device according to the first solution, in which the setting unit sets the practical set value based on a resistance value and an inductance value of a coil that is a load of the injector drive circuit.

[0008] The present invention employs, as a third solution relating to the injector failure detection device, a solution in which, in the first or second solution, the state quantity is a current flowing through the injector drive circuit.

[0009] The present invention provides a fourth solution related to the injector fault detection device according to the third solution, wherein the fault detection unit performs the fault detection for a plurality of components constituting the injector drive circuit based on a plurality of state quantities related to the plurality of components. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an injector failure detection device that can detect a failure in an injector drive circuit more accurately than conventional devices. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a circuit diagram showing the configuration of an injector failure detection device according to an embodiment of the present invention; [Figure 2] 3 is a flowchart showing the operation of the injector failure detection device according to the embodiment of the present invention. [Figure 3] 3 is a characteristic diagram showing the operation of the injector failure detection device according to the embodiment of the present invention; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the injector failure detection device A according to this embodiment is configured by a CPU 1 and a driver IC 2, and targets an injector drive circuit T for failure diagnosis.

[0013] The injector drive circuit T also includes a diode D, a first drive transistor Tr1, a first shunt resistor R1, a coil C, a second drive transistor Tr2, and a second shunt resistor R2.

[0014] Starting with the injector drive circuit T, the diode D is a two-terminal element with its anode terminal connected to the power supply and its cathode terminal connected to the drain terminal of the first drive transistor Tr1. This diode D is a semiconductor element that regulates the flow of current. That is, this diode D allows current to flow from the anode terminal to the cathode terminal, i.e., from the power supply to the first drive transistor Tr1, and blocks current from the cathode terminal to the anode terminal, i.e., from the first drive transistor Tr1 to the power supply.

[0015] The first drive transistor Tr1 is a three-terminal element having a drain terminal, a source terminal, and a gate terminal. The drain terminal of this first drive transistor Tr1 is connected to the cathode terminal of the diode D, the source terminal is connected to one end of the first shunt resistor R1 and the first input terminal of the driver IC2, and the gate terminal is connected to the first output terminal of the driver IC2.

[0016] The first drive transistor Tr1 is set to an ON state (conductive state) or an OFF state (non-conductive state) based on a first control signal input from the driver IC 2. The first control signal is, for example, a PWM (Pulse Width Modulation) signal that sets the duty ratio between the ON state (conductive state) and the OFF state (non-conductive state) of the first drive transistor Tr1.

[0017] The first drive transistor Tr1 is set to the ON state (conducting state) when the first control signal is set to a "high (H) level," and is set to the OFF state (non-conducting state) when the first control signal is set to a "low (L) level." Such a first drive transistor Tr1 determines whether the drive current to the coil C is conducted or not.

[0018] The first shunt resistor R1 is a two-terminal element having one end connected to the source terminal of the first drive transistor Tr1 and the first input terminal of the driver IC2, and the other end connected to one end of the coil C. This first shunt resistor R1 has a predetermined resistance value (first resistance value) and generates a voltage drop according to the current passing through it.

[0019] The first shunt resistor R1 outputs a voltage at one end (first monitor voltage) as a first voltage detection signal to the first input terminal of the driver IC 2. The first monitor voltage is a voltage that changes depending on the current flowing through the first shunt resistor R1, i.e., a voltage that indicates the magnitude of the current flowing through the first shunt resistor R1.

[0020] Such a first voltage detection signal also serves as a first failure detection signal that indicates an operational abnormality (failure) of the first drive transistor Tr1. That is, when the first drive transistor Tr1 fails, the first monitor voltage becomes a voltage that is different from when the first drive transistor Tr1 is normal.

[0021] For example, if the first drive transistor Tr1 is normal, when the first control signal is set to "high (H) level", the first drive transistor Tr1 will be in the ON state (conducting state), but if the first drive transistor Tr1 fails, the first drive transistor Tr1 will remain in the OFF state (non-conducting state) even when the first control signal is set to "high (H) level". Therefore, the first failure detection signal is a detection signal that indicates whether or not the first drive transistor Tr1 has failed.

[0022] Coil C is a drive coil built into the injector. As is well known, an injector is a type of solenoid valve, and when a drive current is applied to coil C (drive coil), the valve element moves by electromagnetic force to open and close. Coil C is the load of the injector drive circuit T.

[0023] The coil C is a two-terminal element having one end connected to the other end of the first shunt resistor R1 and the other end connected to the drain terminal of the second drive transistor Tr2. Note that the coil C has a predetermined resistance value (R value) and inductance value (L value) as circuit constants.

[0024] The second drive transistor Tr2 is a three-terminal element having a drain terminal, a source terminal, and a gate terminal. The second drive transistor Tr2 is a semiconductor element whose drain terminal is connected to the other end of the coil C, whose source terminal is connected to one end of the second shunt resistor R2 and the second input terminal of the driver IC2, and whose gate terminal is connected to the second output terminal of the driver IC2.

[0025] The second drive transistor Tr2 is set to an ON state (conductive state) or an OFF state (non-conductive state) based on a second control signal input from the driver IC 2. The second control signal is, for example, a PWM (Pulse Width Modulation) signal that sets the duty ratio between the ON state (conductive state) and the OFF state (non-conductive state) of the second drive transistor Tr2.

[0026] For example, the second drive transistor Tr2 is set to the ON state (conducting state) when the second control signal is set to a "high (H) level," and is set to the OFF state (non-conducting state) when the second control signal is set to a "low (L) level." Such a second drive transistor Tr2 sets whether the drive current to the coil C is passed or not.

[0027] The second shunt resistor R2 is a two-terminal element having one end connected to the source terminal of the second drive transistor Tr2 and the second input terminal of the driver IC2, and the other end grounded. This second shunt resistor R2 has a predetermined resistance value (second resistance value) and generates a voltage drop according to the current passing through it.

[0028] The second shunt resistor R2 outputs a voltage at one end (second monitor voltage) as a second voltage detection signal to the second input terminal of the driver IC2. The second monitor voltage varies depending on the current flowing through the second shunt resistor R2, i.e., it is a voltage that indicates the magnitude of the current flowing through the second shunt resistor R2.

[0029] Such a second voltage detection signal also serves as a second failure detection signal that indicates an operational abnormality (failure) of the second drive transistor Tr2. That is, when the second drive transistor Tr2 fails, the second monitor voltage becomes a voltage that is different from when the second drive transistor Tr2 is normal.

[0030] For example, if the second drive transistor Tr2 is normal, when the second control signal is set to "high (H) level", the second drive transistor Tr2 will be in the ON state (conducting state), but if the second drive transistor Tr2 fails, the second drive transistor Tr2 will remain in the OFF state (non-conducting state) even when the second control signal is set to "high (H) level". Therefore, the second failure detection signal is a detection signal that indicates whether or not the second drive transistor Tr2 has failed.

[0031] Such first voltage detection signal (first fault detection signal) and second voltage detection signal (second fault detection signal) are a plurality of status signals related to the injector drive circuit T. That is, the first voltage detection signal (first fault detection signal) and the second voltage detection signal (second fault detection signal) are status signals that indicate the operating states of a plurality of components in the injector drive circuit T, namely, the first drive transistor Tr1 and the second drive transistor Tr2.

[0032] The CPU 1 is an integrated circuit that controls the injector drive circuit T via the driver IC 2. In addition to multiple input / output terminals, the CPU 1 also includes a ROM (Read Only Memory), a RAM (Random Access Memory), an arithmetic circuit, an input / output circuit, etc. The multiple input / output terminals of the CPU 1 are connected to multiple input / output terminals of the driver IC 2.

[0033] In the CPU 1, the ROM is a non-volatile memory that stores predetermined control programs and various setting values. As will be described later, the various setting values ​​are updated based on actual measured values ​​of the load characteristics of the injector drive circuit T. In this regard, the various setting values ​​are stored in an electrically writable area of ​​the ROM storage area.

[0034] In the CPU 1, the RAM is a volatile memory that temporarily stores the results of calculations performed by the arithmetic circuits. This RAM contains various registers and counters required for arithmetic processing based on the control program. The arithmetic circuits perform various arithmetic processing based on the control program. The input / output circuits mediate the exchange of signals with the outside world.

[0035] The CPU 1 generates control commands by executing predetermined arithmetic processing in accordance with the control program. The CPU 1 controls the injector drive circuit T by outputting the control commands to the driver IC 2 via multiple input / output terminals. In other words, the CPU 1 is a control device that controls the injector drive circuit T through the cooperation of software and hardware resources.

[0036] The CPU 1 also stores in advance, as initial values, setting values ​​required to evaluate a fault in the injector drive circuit T. The CPU 1 updates these initial setting values ​​using the current FB (current feedback) and voltage FB (voltage feedback) input from the driver IC2, thereby acquiring practical setting values ​​required to detect a fault in the injector drive circuit T.

[0037] Although the details will be described later, the current FB and voltage FB are state quantities that indicate the electrical characteristics of the coil C, which is the load of the injector drive circuit T. In addition, the current FB and voltage FB are also state quantities for evaluating a failure of the injector drive circuit T.

[0038] In addition, the CPU 1 evaluates whether multiple components in the injector drive circuit T, namely the first drive transistor Tr1 and the second drive transistor Tr2, are normal or abnormal based on the current FB input from the driver IC2 and the practical setting value it has acquired.

[0039] That is, the CPU 1 evaluates a failure of the first drive transistor Tr1 based on the current flowing through the first drive transistor Tr1 in the injector drive circuit T and the practical setting value, and also evaluates a failure of the second drive transistor Tr2 based on the current flowing through the second drive transistor Tr2 and the practical setting value.

[0040] The set value and practical set value in this embodiment are the failure undetectable time when evaluating failures in the first drive transistor Tr1 and the second drive transistor Tr2. The failure undetectable time (set value) as the initial value is set to a relatively long time in consideration of variations in the injector drive circuit T and the driver IC2.

[0041] In contrast, the practical set value (practical failure undetectable time) actually used in the failure evaluation of the injector drive circuit T is set to a time shorter than the set value based on the load characteristics of the injector drive circuit T, i.e., the electrical characteristics of the coil C. By evaluating the failure of the injector drive circuit T using such a practical set value (practical failure undetectable time), it is possible to eliminate variations in the injector drive circuit T and the driver IC2 and detect the failure of the injector drive circuit T in a shorter time.

[0042] The CPU 1 of this embodiment corresponds to the setting unit and evaluation unit of the present invention. That is, the CPU 1 sets a practical setting value (practical fault undetectable time) based on the load characteristics of the injector drive circuit T, and performs fault detection of the first drive transistor Tr1 and the second drive transistor Tr2 (multiple components) in the injector drive circuit T based on the practical setting value (practical fault undetectable time) and the current FB (state quantity).

[0043] As described above, the driver IC2 has a first output terminal, a second output terminal, a first input terminal, a second input terminal, and a plurality of input / output terminals. The first output terminal of the driver IC2 is connected to the gate terminal of the first drive transistor Tr1, and the second output terminal is connected to the gate terminal of the second drive transistor Tr2.

[0044] The driver IC2 has a first input terminal connected to the source terminal of the first drive transistor Tr1 and one end of the first shunt resistor R1, and a second input terminal connected to the source terminal of the second drive transistor Tr2 and one end of the second shunt resistor R2. The driver IC2 also has a plurality of input / output terminals connected to a plurality of input / output terminals of the CPU1.

[0045] The driver IC2 generates a first drive signal (first PWM signal) and a second drive signal (second PWM signal) based on a first control command and a second control command input from the CPU 1. The driver IC2 outputs the first drive signal (first PWM signal) to a first drive transistor Tr1 of the injector drive circuit T, and outputs the second drive signal (second PWM signal) to a second drive transistor Tr2.

[0046] The driver IC2 also detects the current (first drive current) flowing through the first drive transistor Tr1 based on the first monitor voltage and the first resistance value by receiving a first voltage detection signal (first fault detection signal) from the injector drive circuit T. The driver IC2 also detects the current (second drive current) flowing through the second drive transistor Tr2 based on the second monitor voltage and the second resistance value by receiving a second voltage detection signal (second fault detection signal) from the injector drive circuit T.

[0047] The driver IC2 outputs the first drive current and the second drive current as a current FB to the CPU 1. The driver IC2 also outputs the first monitor voltage indicated by the first voltage detection signal and the second monitor voltage indicated by the second voltage detection signal as a voltage FB to the CPU 1.

[0048] Next, the operation of the injector failure detection device A according to this embodiment will be described in detail with reference to the flowchart shown in FIG.

[0049] When the CPU 1 starts the control process based on the control program, it first reads various setting values ​​stored in the ROM (step S1). After the various setting values ​​are read, the CPU 1 monitors the first monitor voltage and the second monitor voltage based on the voltage FB sequentially input from the driver IC 2.

[0050] Then, the CPU 1 generates a first control command for the first drive transistor Tr1 and a second control command for the second drive transistor Tr2 based on various set values ​​and the first and second monitor voltages, and outputs them to the driver IC 2 (step S3). The driver IC 2 generates a first drive signal (first PWM signal) and a second drive signal (second PWM signal) based on the first and second control commands input from the CPU 1, and outputs them to the injector drive circuit T.

[0051] Here, the first and second control commands are for obtaining a practical set value (practical failure undetectable time) for the failure undetectable time (set value) described above. That is, the first and second control commands generated in step S3 are for increasing the energizing current (drive current) of the coil C of the injector over time.

[0052] In the injector drive circuit T, the first drive transistor Tr1 performs switching operation at a predetermined timing and duty ratio based on a first drive signal (first PWM signal), and the second drive transistor Tr2 performs switching operation at a predetermined timing and duty ratio based on a second drive signal (second PWM signal).

[0053] The injector changes state from a closed state to an open state when the drive current applied to the coil C based on the first drive signal (first PWM signal) and the second drive signal (second PWM signal) exceeds a predetermined value. That is, when the drive current applied to the coil C exceeds a predetermined value, the valve element of the injector moves from the closed position to the open position.

[0054] Furthermore, the CPU 1 monitors the first drive current and the second drive current based on the current FB sequentially input from the driver IC 2 (step S4). The CPU 1 monitors the first current and the second current at a predetermined time interval, for example, every 1 ms (millisecond).

[0055] Then, the CPU 1 determines whether the current value of the first current and the second current detected values ​​sequentially acquired from the driver IC 2 is greater than the previous value (step S5). If the determination in step S5 is "Yes," the CPU 1 repeats the current monitoring process in step S4. On the other hand, if the determination in step S5 is "No," the CPU 1 calculates the resistance value (R value) and inductance value (L value) of the injector coil C (step S6).

[0056] That is, the CPU 1 calculates the terminal voltage V and drive current I of the coil C based on the first and second monitor voltages and the first and second drive currents, and calculates the R value by dividing the terminal voltage V by the drive current I. The CPU 1 also calculates the L value of the coil C based on the change in the drive current I over time.

[0057] Figure 3 is a characteristic diagram showing the relationship between the change in drive current I over time and the L value of coil C. L of coil C is given as the slope of the change in drive current I over time (drive current curve W). For example, if the drive current I has a previous value Ia (time ta), a current value Ib (time tb), and a final value Is, the L value is given by the following equation (1): L=-tb·R / In{(Ib-Is) / (Ia-Is)} (1)

[0058] The inflection point of the drive current curve W in Fig. 3 indicates a sudden change in inductance (L value) when the injector valve disc separates from the valve seat with which it is in contact. The final value Is of the drive current curve W corresponds to the holding current for holding the valve disc in the open position.

[0059] Such R value and L value of the coil C indicate the load characteristics of the injector drive circuit T, i.e., the electrical characteristics of the coil C. The CPU 1 acquires a practical set value (practical failure undetectable time) based on such R value and L value of the coil C, i.e., the actual measured values ​​of the electrical characteristics of the coil C (step S7).

[0060] For example, the CPU 1 acquires the practical failure undetectable time (practical set value) corresponding to the actually measured values ​​of the R value and the L value by referring to a conversion table between the R value, the L value, and the practical failure undetectable time. After acquiring the practical set value (practical failure undetectable time) in this way, the CPU 1 writes the practical set value (practical failure undetectable time) into an electrically writable area of ​​the ROM (step S8).

[0061] That is, the failure undetectable time (set value) previously stored as an initial value in the ROM of the CPU 1 is updated based on the actual measured value of the load characteristics of the injector drive circuit T. Then, the CPU 1 performs failure detection of the injector drive circuit T by using the practical set value (practical failure undetectable time) updated and registered in the ROM.

[0062] The injector fault detection device A of this embodiment is a device that detects faults in the injector drive circuit T based on the state quantity of the injector drive circuit T, and is equipped with a CPU 1 (setting unit) that sets a practical setting value (practical fault undetectable time) based on the electrical characteristics of the coil C, i.e., the load characteristics of the injector drive circuit T, and a CPU 1 (fault detection unit) that detects faults in the injector drive circuit T based on the practical setting value (practical fault undetectable time) and the normal current FB (normal state quantity).

[0063] According to this embodiment, the practical setting value (practical failure detection undetectable time) is set based on the load characteristics of the injector drive circuit T, so that an injector failure detection device A can be provided that can detect failures in the injector drive circuit T more accurately than conventional devices.

[0064] In addition, in the injector failure detection device A of this embodiment, the CPU 1 (setting unit) sets a practical failure detection undetectable time (practical setting value) based on the R value (resistance value) and L value (inductance) of the coil C, which is the load of the injector driving circuit T.

[0065] According to this embodiment, the practical failure detection undetectable time (practical set value) is set based on the R value (resistance value) and L value (inductance) of the coil C, so that it is possible to detect failures in the injector drive circuit T more accurately than conventional methods.

[0066] In the injector failure detection device A according to this embodiment, the state quantity is the current flowing through the injector drive circuit R, i.e., the drive current of the injector. According to this embodiment, it is possible to detect a failure in the injector drive circuit T more accurately than in the past.

[0067] Furthermore, in the injector fault detection device A according to this embodiment, the CPU 1 (fault detection unit) detects faults in the first drive transistor Tr1 and the second drive transistor Tr2 (multiple components) that constitute the injector drive circuit T. According to this embodiment, it is possible to detect faults in the multiple components that constitute the injector drive circuit T more accurately than in the past. [Explanation of symbols]

[0068] A. Injector failure detection device C coil D diode R1 First shunt resistor R2 Second shunt resistor T Injector drive circuit Tr1 First drive transistor Tr2 Second drive transistor 1 CPU (setting section, fault detection section) 2 Driver IC

Claims

1. 1. An injector failure detection device for detecting a failure in an injector drive circuit based on a state quantity of the injector drive circuit, a setting unit that sets a practical set value based on the load characteristics of the injector drive circuit; a fault detection unit that performs the fault detection based on the practical setting value and the state quantity; An injector failure detection device comprising:

2. 2. The injector failure detection device according to claim 1, wherein the setting unit sets the practical set value based on a resistance value and an inductance value of a coil that is a load of the injector drive circuit.

3. 3. The injector failure detection device according to claim 1, wherein the state quantity is a current flowing through the injector drive circuit.

4. 4. The injector failure detection device according to claim 3, wherein the failure detection unit detects the failure of the plurality of components constituting the injector drive circuit based on a plurality of state quantities related to the plurality of components.

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