Injector driver

Abstract

To provide an injector driver capable of suppressing damage caused by heat generation of an injector.SOLUTION: An injector driver supplies a drive current to drive an injector, and includes a current detection unit that detects the current value of the drive current in the injector, and a current time acquisition unit that acquires the time the drive current is supplied to the injector, and stops the supply of the drive current to the injector based on the current value and the current time.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Patent Document 1 listed below discloses a solenoid valve drive device that accurately diagnoses whether an appropriate drive current is being supplied to a solenoid valve to be driven. This solenoid valve drive device includes a drive unit that supplies a drive current to the solenoid valve based on an injection signal given from an electronic control device, and a fail-safe signal generation unit that generates a fail-safe signal based on a load current and feeds this back to the electronic control device. The fail-safe signal generation unit generates a fail-safe signal that becomes active corresponding to a period during which the load current is flowing at a predetermined amount or more, and the electronic control device diagnoses whether the drive current is appropriate based on the active duration of the fail-safe signal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 09-317931 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned background art, a fault diagnosis of the solenoid valve is performed based on the magnitude of the drive current during the active time width of the fail-safe signal. Therefore, the above-mentioned background art does not suppress or avoid damage to the injector caused by heat generated in the solenoid valve (injector) due to the passage of the drive current, etc.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an injector drive device that can suppress damage caused by heat generation in the injector. [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 drive device, a means for stopping the supply of the drive current to the injector based on the current value and the current time, in the injector drive device that drives the injector by supplying a drive current to the injector, the means including: a current detection unit that detects a current value of the drive current in the injector; and a current time acquisition unit that acquires a current time for which the drive current is supplied to the injector, and

[0007] The present invention employs, as a second solution related to the injector drive device of the first solution, a means for stopping the supply of the drive current to the injector when the current value exceeds a first current threshold and the current flow time exceeds a first time threshold.

[0008] The present invention provides a third solution related to the injector drive device of the second solution, in which the supply of the drive current to the injector is stopped when the current value exceeds a second current threshold value that is smaller than the first current threshold value and the current flow time exceeds a second time threshold value that is longer than the first time threshold value.

[0009] The present invention employs, as a fourth solution related to the injector drive device, the third solution, in which the first current threshold Er1 is set to a value greater than a peak current value of the drive current, and the second current threshold is set to a value between the peak current value and a holding current value of the drive current. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide an injector driving device that can suppress damage caused by heat generation in the injector. [Brief explanation of the drawings]

[0011] [Figure 1]1 is a circuit diagram showing a configuration of an injector driving device according to an embodiment of the present invention; [Figure 2] 3 is a flowchart illustrating an operation of the injector driving device according to the embodiment of the present invention. [Figure 3] FIG. 3 is a waveform diagram showing the operation of the injector driving device according to the embodiment of the present invention. 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 driving device A according to this embodiment is made up of a CPU 1, a driver IC 2, and a driving circuit 3, and is configured to drive an injector F.

[0013] As shown in the figure, the drive circuit 3 includes a diode D, a first drive transistor Tr1, a first shunt resistor R1, a second drive transistor Tr2, and a second shunt resistor R2. The injector F also includes a drive coil C.

[0014] The CPU 1 is an integrated circuit that controls the drive circuit 3 via the driver IC 2. In addition to multiple input / output terminals, the CPU 1 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.

[0015] In the CPU 1, the ROM is a non-volatile memory that stores a predetermined control program and various setting values. In the CPU 1, the RAM is a volatile memory that temporarily stores the calculation results of the arithmetic circuit. This RAM stores various registers and counters required for arithmetic processing based on the control program. The arithmetic circuit performs various arithmetic processing based on the control program. In addition, the input / output circuit mediates the exchange of signals with the outside.

[0016] The CPU 1 executes predetermined calculations in accordance with the control program to generate a control command corresponding to the current FB (current feedback). The current FB is a current detection signal indicating the current value E of the drive current for the injector F input from the driver IC2. The CPU 1 generates a control command using the current FB as a feedback amount (return amount) and outputs it to the driver IC2.

[0017] The CPU 1 also has a function to protect the injector F based on the current FB. That is, the CPU 1 has a function to obtain the energization time T of the drive current based on the current FB, and outputs an output stop command to the driver IC2 based on the current value E of the drive current obtained from the current FB and the energization time T of the drive current obtained by the CPU 1 itself.

[0018] Such a CPU 1 corresponds to the current flow time detection unit of the present invention. That is, the CPU 1 detects the current flow time T of the drive current in the injector F, and generates an output stop command based on the current value E of the drive current and the current flow time T of the drive current, and outputs the command to the driver IC 2 to stop the supply of the drive current from the drive circuit 3 to the injector F.

[0019] 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.

[0020] 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.

[0021] 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 the first drive transistor Tr1 of the drive circuit 3, and outputs the second drive signal (second PWM signal) to the second drive transistor Tr2.

[0022] The driver IC2 also detects the 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 from the drive circuit 3. The driver IC2 also detects the 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 from the drive circuit 3.

[0023] The driver IC2 outputs the first drive current and the second drive current as a current detection signal to the CPU 1. This current detection signal is a signal indicating the current value E of the drive current of the injector F. In other words, the driver IC2 is a functional component that detects the current value E of the drive current in the injector F. The driver IC2 corresponds to the energization current detection unit of the present invention.

[0024] The drive circuit 3 generates a drive current based on a first drive signal (first PWM signal) and a second drive signal (second PWM signal) input from the driver IC 2. The drive circuit 3 supplies the drive current to the injector F.

[0025] In this drive circuit 3, 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] Next, as is well known, the injector F is an electromagnetic valve that injects fuel into the combustion chamber of the engine. This injector F opens and closes with a drive current that is passed through a drive coil C by a drive circuit 3. In this injector F, the valve opening time is a parameter that sets the flow rate (injection amount) of fuel injected into the combustion chamber, and is governed by the time that the drive current is passed through the drive coil C.

[0037] The drive coil C is an electronic component incorporated into the injector F and serves as a load for the drive circuit 3. The drive 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. The drive coil C has predetermined resistance and inductance as circuit constants.

[0038] Next, the operation of the injector driving device A according to this embodiment will be described in detail with reference to the flowchart shown in FIG.

[0039] In the injector driving device A, the driver IC2 detects the current value E of the driving current in the injector F (step S1). Then, the driver IC2 outputs this current value E as a current detection signal to the CPU 1. The CPU 1 takes in the current value E as the current FB based on the current detection signal.

[0040] Then, the CPU 1 acquires the energization time T of the drive current in the injector F (step S2). That is, the CPU 1 acquires the cumulative time of the drive current in the injector F as the energization time T based on the current detection signal. That is, the energization time T is the cumulative time of energization of the drive current from the drive circuit 3 to the drive coil C from the time when the injector drive device A started driving the injector F to the present.

[0041] After acquiring the current flow time T in this way, the CPU 1 determines whether the current value E of the drive current exceeds a predetermined first current threshold value Er1 (step S3). This first current threshold value Er1 is a current equivalent to the upper limit of the allowable range of the drive current, and is set to, for example, 6.2 A (amperes).

[0042] If the determination in step S3 is "Yes," the CPU 1 determines whether the energization time T of the drive current exceeds a predetermined first time threshold Tr1 (step S4). This first time threshold Tr1 is set in accordance with the first current threshold Er1 so as to avoid damage to the injector F due to heat generation caused by the energization of the drive current, and is a time equivalent to the upper limit of the allowable range of the drive current, and is set to, for example, 1.8 seconds.

[0043] If the determination in step S4 is "Yes," the CPU 1 generates an output stop command and outputs it to the driver IC 2 (step S5). As a result, the driver IC 2 generates a first drive signal (first PWM signal) and a second drive signal (second PWM signal) based on the output stop command, thereby stopping the supply of drive current from the drive circuit 3 to the drive coil C.

[0044] On the other hand, if the determination in step S3 is "No," the CPU 1 determines whether the current value E of the drive current exceeds a predetermined second current threshold Er2 (step S6). This second current threshold Er2 is a current smaller than the upper limit of the allowable range of the drive current, and is set to, for example, 2.5 A (amperes).

[0045] If the determination in step S6 is "Yes," the CPU 1 determines whether the energization time T of the drive current exceeds a predetermined second time threshold Tr2 (step S7). This second time threshold Tr2 is set in accordance with the second current threshold Er2 so as to avoid damage to the injector F due to heat generation caused by the energization of the drive current, and is set to, for example, 9 seconds, which is slightly longer than the upper limit of the allowable range of the energization of the drive current.

[0046] If the determination in step S7 is "Yes," the CPU 1 generates an output stop command and outputs it to the driver IC 2 (step S5). As a result, the driver IC 2 generates a first drive signal (first PWM signal) and a second drive signal (second PWM signal) based on the output stop command, thereby stopping the supply of drive current from the drive circuit 3 to the drive coil C.

[0047] On the other hand, if the determination in step S6 is "No," the CPU 1 repeats the process in step S1. Also, if the determination in step S7 is "No," the CPU 1 repeats the process in step S1.

[0048] That is, when the current value E of the drive current exceeds the first current threshold Er1 and the energization time T of the drive current exceeds the first time threshold Tr1, the CPU 1 stops the supply of the drive current from the drive circuit 3 to the drive coil C. The CPU 1 also stops the supply of the drive current from the drive circuit 3 to the drive coil C when the current value E of the drive current exceeds the second current threshold Er2 and the energization time T of the drive current exceeds the second time threshold Tr2.

[0049] 3 is a waveform diagram showing the relationship between the current value E of the drive current and the first and second current threshold values ​​Er1 and Er2. As shown in Fig. 3, when the injector F is shifted from a closed state to an open state, the current value E of the drive current is initially set to a relatively high value (peak current value E1), and then set to a holding current value E2 required to maintain the open state.

[0050] That is, the peak current value E1 is set to a value greater than the holding current value E2 in order to increase the valve opening speed of the injector F. By being driven by a drive current with such a current profile, the injector F can inject a more accurate amount of fuel into the combustion chamber.

[0051] For such a drive current value E, the first current threshold value Er1 is set to a value significantly greater than the peak current value E1, as shown in the figure, while the second current threshold value Er2 is set to a value between the peak current value E1 and the holding current value E2, as shown in the figure.

[0052] The injector driving device A of this embodiment is a device that supplies a driving current to an injector F to drive it, and is equipped with a driver IC2 (current flow detection unit) that detects the current value E of the driving current in the injector, and a CPU1 (current flow time acquisition unit) that acquires the current flow time T of the driving current in the injector F, and stops the supply of the driving current to the injector F based on the current value E and the current flow time T.

[0053] According to this embodiment, the supply of drive current to the injector F is stopped based on the current value E and the current flow time T, so it is possible to provide an injector drive device A that can suppress damage caused by heat generation in the injector F.

[0054] The injector driving device A according to this embodiment stops supplying the driving current to the injector F when the current value E exceeds a first current threshold value Er1 and the current application time T exceeds a first time threshold value Tr1. According to this embodiment, it is possible to effectively prevent damage to the injector F due to heat generation.

[0055] The injector driving device A according to this embodiment stops supplying the driving current to the injector F when the current value E exceeds a second current threshold value Er2 that is smaller than the first current threshold value Er1 and the current application time T exceeds a second time threshold value Tr2 that is longer than the first time threshold value Tr1. This embodiment makes it possible to effectively prevent damage to the injector F due to heat generation.

[0056] Furthermore, in the injector driving device A according to this embodiment, the first current threshold value Er1 is set to a value greater than the peak current value E1 of the driving current, and the second current threshold value Er2 is set to a value between the peak current value E1 and the holding current value E2 of the driving current. According to this embodiment, it is possible to effectively prevent damage to the injector F due to heat generation. [Explanation of symbols]

[0057] A Injector driver C drive coil D diode R1 First shunt resistor R2 Second shunt resistor Tr1 First drive transistor Tr2 Second drive transistor 1 CPU (drive unit, power-on time detection unit, temperature acquisition unit) 2 Driver IC (driver, current detector) 3 Drive circuit (drive unit)

Claims

1. An injector driver that supplies a drive current to an injector to drive the injector, an energization current detection unit that detects a current value of the drive current in the injector; a current flow time acquisition unit that acquires a current flow time of the drive current in the injector, an injector driving device that stops supplying the driving current to the injector based on the current value and the energization time;

2. 2. The injector driver according to claim 1, wherein the supply of the drive current to the injector is stopped when the current value exceeds a first current threshold and the current application time exceeds a first time threshold.

3. 3. The injector drive device according to claim 2, wherein the supply of the drive current to the injector is stopped when the current value exceeds a second current threshold value that is smaller than the first current threshold value and the current flow time exceeds a second time threshold value that is longer than the first time threshold value.

4. 4. The injector drive device according to claim 3, wherein the first current threshold value Er1 is set to a value greater than a peak current value of the drive current, and the second current threshold value is set to a value between the peak current value and a holding current value of the drive current.

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