JP7313182B2 - Electronic control device and abnormality detection method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electronic control device and an abnormality detection method, and is particularly suitable for application to an electronic control device for a load that requires a large current to drive.

A conventional vehicle is provided with a solenoid valve as an actuator for transmission oil pressure control which is driven by a DC battery voltage and whose operation is controlled. A drive circuit for driving the solenoid valve is provided, for example, in a TCU (Transmission Control Unit). In such a drive circuit, the high voltage side of the solenoid valve is connected to the current switch circuit portion and the actual current value detection portion. On the other hand, the downstream side of the solenoid valve is directly connected to ground.

In this drive circuit, if an abnormality such as a short circuit (hereinafter referred to as a "short battery") in the connection line between the terminal to be connected to the solenoid valve (hereinafter referred to as "solenoid terminal") and the battery voltage, a disconnection at the solenoid terminal (hereinafter referred to as "open load"), or a short circuit between the solenoid terminal and ground (hereinafter referred to as "short ground") occurs, it is required to reliably detect each abnormality.

International publication 2015/093219A1 JP 2008-157304 A JP 2006-252416 A

As described above, it is desired to distinguish and reliably detect each abnormality such as short battery, open load, and short ground.

An object of the present invention is to improve short ground detectability.

According to one aspect of the present invention, in an electronic control device (1) for controlling the operation of a drive target (56) connected to an output terminal (32) by switching ON/OFF a driving current input from an input terminal (31) and outputting it from an output terminal (32), a driving circuit (24) for switching ON/OFF the driving current and outputting the driving current; a control section (200) for controlling the operation of the driving circuit (24);a current detection unit (24B) for detecting a drive current flowing through the drive circuit (24);wherein the control unit (200) detects a short circuit from the output terminal (32) to the ground when the drive current flowing through the drive circuit (24) exceeds the upper limit of the drive current allowed for the duty ratio instructed to the drive circuit (24).When the drive current flowing through the drive circuit (24) detected by the current detection unit (24B) exceeds a certain threshold value (Th1) regardless of the duty ratio, the control unit (200) detects a short circuit from the output terminal (32) to the ground, and the control unit (200) determines whether or not the drive current flowing through the drive circuit (24) exceeds the threshold value (Th1), and determines whether the drive current exceeds the upper limit. Preceding the determination to detect the short circuit;An electronic controller (1) is provided.

According to another aspect of the present invention, a drive circuit (24) switches ON/OFF of a drive current input from an input terminal (31) and outputs the drive current from an output terminal (32) to control the operation of a drive target (56) connected to the output terminal (32); and when the drive current flowing through the drive circuit (24) exceeds the upper limit of the drive current allowed for the duty ratio instructed to the drive circuit (24), the output terminal (32) is grounded. detecting a short circuit indetecting a short-circuit from the output terminal (32) to the ground when the drive current flowing through the drive circuit (24) detected by a current detection unit (24B) for detecting the drive current flowing through the drive circuit (24) exceeds a predetermined threshold (Th1) regardless of the duty ratio, determining whether or not the drive current flowing through the drive circuit (24) exceeds the threshold (Th1) before determining whether the drive current exceeds the upper limit. and performing detection of the short circuit;An anomaly detection method is provided.

ADVANTAGE OF THE INVENTION According to this invention, the detectability of a short ground can be improved.

1 is a circuit diagram of an electronic control unit according to this embodiment; FIG. 4 is a flowchart showing drive control processing; 4 is a graph showing drive currents when a short ground occurs when no resistor is interposed. FIG. 10 is a graph showing drive currents when a short ground occurs when a resistor is interposed; FIG. 4 is a graph showing the correlation between duty ratio and drive current;

An embodiment of the present invention will be described with reference to the drawings. Note that the following description does not limit the present invention, and can be appropriately modified within the scope of the present invention.

FIG. 1 shows a schematic configuration of an electronic control unit 1. As shown in FIG. The electronic control unit 1 is, for example, a TCU (Transmission Control Unit) that controls the operation of the transmission.

The electronic control unit 1 receives power from a battery 35 mounted on the vehicle through an input terminal 31 . The input power is input to, for example, six drive circuits 24 via a reverse protection 33 and a CHSS (Common High Side Switch) 34 . In the illustrated example, one drive circuit 24 is shown as an example. The electric power input into the drive circuit 24 is switched ON/OFF based on the control signal from the control unit 200, and is output from the output terminal 32 to the load SOL.

The drive circuit 24 controls the transmission as a controlled object according to the operation of a load SOL such as a solenoid that is a part of the shift actuator 56 that is driven. This solenoid is for example an actuator for driving a hydraulic valve of a vehicle transmission.

A current control switch (hereinafter sometimes referred to as IHSS: Individual High Side Switch) 24A, a current detection section 24B, a shunt resistor 24D and a flywheel diode 24E are provided on the left side of the drive circuit 24 .

Current control switch 24A is connected to control section 200 . The control unit 200 controls the current amount of the driving current I to be supplied to the load SOL by performing ON/OFF control on the current control switch 24A while changing the duty ratio of each pulse width in pulse width control, for example.

The current detector 24B is provided between the load SOL and the current control switch 24A. The current detection section 24B includes a shunt resistor 24D, and detects the drive current I supplied from the battery 35 to the load SOL by measuring the current flowing through the shunt resistor 24D. The current amount of the driving current I detected by the current detection section 24B is fed back to the control section 200 as the detection current IN1.

Control unit 200 adjusts the amount of driving current I supplied to load SOL by controlling the duty ratio of current control switch 24A based on the amount of detected current IN1 detected by current detecting unit 24B. Further, the control unit 200 determines whether or not an abnormality has occurred according to the current amount of the detected current IN1 detected by the current detection unit 24B.

On the right side of the drive circuit 24, resistors R1, R2, and R3 are provided in series between, for example, a power supply voltage of 5V and the ground, and the junction of the resistors R2 and R3 is connected to the control unit 200. The control unit 200 is fed back with a voltage (corresponding to a "specific voltage" to be described later) at the connection point between the resistors R2 and R3 according to the voltage division ratio of the resistors R1, R2, and R3. The value of the voltage fed back in this way is also referred to as detection voltage IN2. In other words, the value of the voltage at the junction of the resistors R2 and R3 is fed back to the controller 200 as the detection voltage IN2.

FIG. 2 shows an example of drive control processing. The control unit 200 determines whether or not the detected current IN1 fed back from the current control switch 24A exceeds a certain threshold Th1 (hereinafter referred to as first threshold Th1) regardless of the instructed duty ratio (step S1). That is, the control unit 200 constantly monitors whether or not a large drive current I exceeding the first threshold Th1 flows through the drive circuit 24 .

For example, when the first threshold Th1 is 1.8 A and the detected current IN1 exceeds 1.8 A (step S1: YES), the control section 200 detects the occurrence of the short ground SG (step S2). On the other hand, when the detected current IN1 does not exceed 1.8 A (step S1: NO), the control unit 200 executes step S3.

In step S3, the control unit 200 determines whether or not the detected current IN1 exceeds the upper limit of the drive current I allowed for the current duty ratio instructed to the current control switch 24A (step S3). That is, the control unit 200 monitors whether or not the driving current I exceeding the upper limit allowed for the duty ratio instructed to the driving circuit 24 has flowed through the driving circuit 24 .

Even if the first threshold value Th1 is not exceeded, if the drive current I exceeding the upper limit allowed for the duty ratio flows through the drive circuit 24, the drive current I is flowing with a current amount larger than the current amount to be controlled by the duty ratio, and there is a possibility of short ground SG. Therefore, when the detected current IN1 exceeds the upper limit (step S3: YES), the controller 200 detects the occurrence of the short ground SG (step S2). On the other hand, if the detected current IN1 does not exceed the upper limit (step S3: NO), the controller 200 executes step S4.

In step S4, if the first condition that the drive current I flowing through the drive circuit 24, i.e., the amount of the detected current IN1 detected by the current detector 24B is smaller than a predetermined value Thi and the duty ratio thereof is larger than a predetermined value Thd, or the second condition that the detected current IN1 is greater than a predetermined decrease rate and the duty ratio is greater than a predetermined rise rate, the control unit 200 controls the load based on the specific voltage fed back as the detected voltage IN2. A disconnection in SOL (open load OP) and a short circuit in battery 35 (short battery SB) are distinguished from each other.

For example, when the predetermined value Thi is 41 mA and the predetermined value Thd is 23.2%, the control unit 200 determines whether the current IN1 detected by the current detection unit 24B is less than 41 mA and its duty ratio exceeds 23.2% (first condition), or whether the current IN1 detected by the current detection unit 24B is greater than a predetermined decrease rate and the duty ratio exceeds a predetermined increase rate (second condition). Determine (step S4).

That is, the control unit 200 constantly monitors whether or not the first condition is established that the driving current I flowing through the shunt resistor 24D and the load SOL is equal to or less than a predetermined value Thi that is close to 0 and that the duty ratio value based on the drive instruction by the current control switch (IHSS) 24A, which is a current switch circuit portion for solenoid drive control, is greater than the predetermined value Thd. When the first condition or the second condition is established, the control unit 200 determines that the drive current I does not flow sufficiently even though the drive instruction for the load SOL is given at a certain magnitude, that is, that there is a possibility of an abnormality, that is, a short battery SB or an open load OP.

If the above-described first condition or second condition is not satisfied (step S4: NO), the control unit 200 determines that there is no abnormality (normal state) (step S7). On the other hand, if the first condition or the second condition is satisfied (step S4: YES), the control unit 200 turns off the current control switch 24A (step S5).

Further, as a method for confirming the details of the abnormality, the control unit 200 measures the potential upstream of the shunt resistor 24D while the current control switch 24A is once turned off, for example, to carry out detailed judgment. Specifically, the control unit 200 compares two thresholds having different magnitudes, eg, 2.13 V and 3.98 V, with the detection voltage IN2.

First, the control unit 200 determines whether the detected voltage IN2 is less than 2.13 V (step S6). When the detected voltage IN2 is less than 2.13 V (step S6: YES), the control unit 200 determines that there is no abnormality (normal state) (step S7). On the other hand, if the detected voltage IN2 is not less than 2.13 V (step S6: NO), the control unit 200 executes step S8.

In step S8, the controller 200 determines whether or not the third condition that the detected voltage IN2 is equal to or greater than 2.13 V and less than 3.98 V is satisfied. If the detected voltage IN2 is equal to or greater than 2.13 V and less than 3.98 V (step S8: YES), the control unit 200 detects the open load OP (step S9).

On the other hand, when the detected voltage IN2 is not less than 2.13 V or more and less than 3.98 V (step S8: NO), the control unit 200 detects the short battery SB (step S10).

As described above, the control unit 200 detects the short ground SG based on the detected current IN1, and distinguishes between a disconnection in the load SOL (open load OP) and a short circuit in the battery 35 (short battery SB) based on the detected voltage IN2.

The control unit 200 uses not only the condition that the drive current I exceeds the first threshold value Th1 but also the condition that the drive current I exceeds the upper limit of the drive current allowed for the duty ratio as the condition for detecting the short ground SG. In the case of a normal short ground SG, a large current flows, so the short ground SG can be detected under the condition that the first threshold Th1 is exceeded. However, if the short ground SG is generated via the small resistance 72 due to the adhesion of carbides of dust, only the drive current I less than the first threshold Th1 flows, and there is a possibility that the short ground SG will not be detected only under the condition that the first threshold Th1 is exceeded. However, according to the condition that the allowable upper limit for the duty ratio is exceeded, even if the drive current I to be monitored is less than the first threshold Th1, if the allowable upper limit is exceeded, the occurrence of the short ground SG can be detected, and the detectability of the short ground SG is improved.

Further, in the present embodiment, the control unit 200 detects the drive current I that is equal to or greater than the first threshold Th1 before detecting the drive current I that exceeds the upper limit of the duty ratio. Therefore, it is possible to detect the short ground SG through which a large current flows first and take early countermeasures.

FIG. 3 shows an example of drive current I when a short ground occurs without passing through resistor 72 . In FIG. 3, the vertical axis indicates the driving current I, and the horizontal axis indicates the time T. As shown in FIG. The waveform of the driving current I in FIG. 3 is a combined waveform of the current flowing through the load SOL and the current flowing to the ground due to the occurrence of the short ground SG.

As shown in FIG. 3, the drive current I sharply rises from the time Tsg when the output terminal 32 is short-circuited to the ground. Therefore, the short ground SG can be detected by determining whether or not the drive current I exceeds the first threshold Th1 in the process of step S1 described above. In FIG. 3, after the first threshold value Th1 is exceeded, the current control switch 24A is turned off by the detection of the short ground SG, so the driving current I drops to zero.

FIG. 4 shows an example of drive current I when a short ground occurs via resistor 72 .
As shown in FIG. 4, when the output terminal 32 is short-circuited to the ground via the resistor 72, a drive current I that does not exceed the first threshold Th1 but is larger than the current to be controlled by the duty ratio flows from the short-circuit time Tsg. Therefore, by judging whether or not the driving current I exceeds the allowable upper limit for the currently instructed duty ratio in the process of step S3 described above, it is possible to detect a short ground SG in the case of a short circuit to the ground via the resistor 72.

FIG. 5 shows the correlation between duty ratio Dy (%) and drive current I (mA).
In FIG. 5, the area surrounded by straight lines y1 and y2 is the normal use range 81 of the load SOL. A straight line y1 represents the upper limit of the allowable drive current I with respect to the duty ratio Dy, and a straight line y2 represents its lower limit. The upper limit and lower limit are proportional to the duty ratio Dy, and the width from the upper limit to the lower limit of the normal use range 81 corresponds to the fluctuation range of the drive voltage, the temperature fluctuation range of the resistance value, and the like. The range in which the short ground SG can be detected only by the judgment in step S1 is the region 82 that exceeds the first threshold Th1 regardless of the duty ratio Dy, but by making the judgment in step S3, the region 83 that is less than the first threshold Th1 but is not within the normal use range 81 also becomes the range in which the short ground SG can be detected.

Note that the control unit 200 may compare the detected drive current I not only with the upper limit but also with the lower limit of the allowable current value for the duty ratio Dy, and if the drive current I is equal to or less than the upper limit and equal to or more than the lower limit, it may be determined that there is no abnormality and that the state is normal.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist thereof.

DESCRIPTION OF SYMBOLS 1... Electronic control unit, 24... Drive circuit, 24A... Current control switch, 24B... Current detection part, 200... Control part

Claims (3)

In an electronic control device (1) that controls the operation of a drive target (56) connected to an output terminal (32) by switching ON/OFF a drive current input from an input terminal (31) and outputting it from an output terminal (32),
a drive circuit (24) for switching ON/OFF of the drive current and outputting the drive current;
a control unit (200) for controlling the operation of the drive circuit (24);
a current detection unit (24B) that detects a drive current flowing through the drive circuit (24),
The control unit (200) detects a short circuit from the output terminal (32) to the ground when the drive current flowing through the drive circuit (24) exceeds the upper limit of the drive current allowed for the duty ratio instructed to the drive circuit (24),
The control unit (200) detects a short circuit from the output terminal (32) to the ground when the drive current flowing through the drive circuit (24) detected by the current detection unit (24B) exceeds a certain threshold value (Th1) regardless of the duty ratio,
The control unit (200) determines whether the drive current flowing through the drive circuit (24) exceeds the threshold value (Th1) prior to determining whether the drive current exceeds the upper limit to detect the short circuit.
Electronic control unit (1). When the drive current flowing through the drive circuit (24) is equal to or less than the upper limit and equal to or more than the lower limit of the drive current allowed for the duty ratio, the control unit (200) determines that the state is normal.
Electronic control unit (1) according to claim 1 . a step of controlling the operation of a drive target (56) connected to the output terminal (32) by switching ON/OFF of the drive current input from the input terminal (31) by the drive circuit (24) and outputting it from the output terminal (32);
detecting a short circuit from the output terminal (32) to ground when the drive current flowing through the drive circuit (24) exceeds the upper limit of the drive current allowed for the duty ratio instructed to the drive circuit (24);
detecting a short circuit from the output terminal (32) to the ground when the drive current flowing through the drive circuit (24) detected by a current detection unit (24B) for detecting the drive current flowing through the drive circuit (24) exceeds a certain threshold (Th1) regardless of the duty ratio;
including
determining whether the drive current flowing through the drive circuit (24) exceeds the threshold value (Th1) prior to determining whether the drive current exceeds the upper limit to detect the short circuit;
Anomaly detection method.

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