JP2508742B2 - Vehicle electrical equipment - Google Patents

Description

The present invention relates to an electric device used for a vehicle, and more particularly to a ground wire of a power electric circuit and a ground of a control electric circuit which require a large amount of electric power. The present invention relates to an electric device for a vehicle, which is configured to be separated from a wire.

(Prior Art) Conventionally, various electric components have been mounted on a vehicle and are operated by being supplied with electric power from a vehicle-mounted battery. Further, these electric components are mixed with a power system electric circuit that requires a large amount of electric power and a control system electric circuit that handles a small electric signal. The noise, the fluctuation of the ground level, and the like, which are caused by factors such as load fluctuations in the power system electric circuit, are extremely large values relative to the control system electric circuit, and cause malfunctions. Therefore, normally, the ground line (hereinafter, also simply referred to as a ground) between the power system electric circuit and the control system electric circuit is separated to supply electric power.

At this time, the body of the vehicle may be used for the ground of the power system that requires a large amount of power, but a wire harness is used for the ground of the control system electric circuit, and the wire harness is cut or There is a possibility that the control system electric circuit may become inoperable due to the grounding of the control system electric circuit due to a defective connector or the like.

Therefore, by connecting the anode of the diode to the ground of the control system electric circuit and the cathode to the ground of the power system electric circuit, even if the ground of the control system electric circuit is open, the ground of the power system electric circuit is borrowed. Ensures the operation of the control system electric circuit. As a result, the vehicle can always ensure the traveling ability.

(Problems to be solved by the invention) The regular ground of the control system electric circuit is opened,
When the control system electric circuit operates by using the ground of the power system electric circuit as a temporary ground through the diode, the control system electric circuit is affected by the load fluctuation of the power system electric circuit,
The ground level increases by the amount of the forward voltage drop of the diode. For this reason, the accuracy of detection of the analog amount executed by the control system electric circuit is deteriorated, and it may not be possible to expect a normal operation. Therefore, the fuel economy, emissions, drivability, etc. of the vehicle that is the control target of the control system electric circuit may deteriorate.

However, as described above, the control system electric circuit obtains a temporary ground and continues to operate, and the traveling capacity of the vehicle is secured.Therefore, the deterioration of the operating state of the vehicle must be recognized by the user of the vehicle. However, there is a problem in that it is continuously used in an aggravated driving state.

When the detection signal of the control system electric circuit deviates from the normal value as described above, the control accuracy for the internal combustion engine deteriorates and the above problems occur. Even when mounted on an internal combustion engine, careful attention has been paid so far. For example, JP-A-61-25946
According to the technique disclosed in the publication, a measure for ensuring the accuracy of the control system electric circuit is presented. However, even in the control system electric circuit mounted on the internal combustion engine with such meticulous attention, the accuracy is deteriorated when the fluctuation of the ground level occurs, and an urgent countermeasure is demanded.

The present invention has been made to solve the above problems, and in an electric device for a vehicle that can operate even if the ground line of the control system electric circuit has an open failure, the open failure can be reliably detected and early detection is possible. The purpose is to enable repairs.

Configuration of the Invention (Means for Solving the Problems) The means constituted by the present invention for solving the above problems is, as shown in the basic configuration diagram of FIG. 1, a power system electric circuit requiring a large amount of power. P ground line
PG and the ground line SG of the control system electric circuit S are configured separately, and the anode is connected to the ground line SG of the control system electric circuit S, and the cathode is connected to the ground line PG of the power system electric circuit P. In a vehicular electric device including a diode D connected to the vehicle, the electric potential difference detecting means C1 for detecting the electric potential difference in the forward direction of the diode D, and the control when the detection result of the electric potential difference detecting means C1 exceeds a predetermined value. In the ground line SG of the system electric circuit S, it is judged that the downstream side K of the diode D is connected to the anode of the diode D is disconnected, and an informing means C2 for performing an operation to inform the outside of the electric device to that effect. The gist of the present invention is an electric device for a vehicle, which comprises:

(Operation) Also in the vehicle electric device of the present invention, the ground line SG of the control system electric circuit S and the ground line PG of the power system electric circuit P
Are separated from each other, and the influence of noise from the power system electric circuit P on the control system electric circuit S is avoided. Further, since the anode is connected to the ground line SG of the control system electric circuit S and the cathode is connected to the ground line PG of the power system electric circuit P, the ground line SG of the control system electric circuit S is provided. Even if the downstream side K is disconnected (open failure) from the point where the anode of the diode D is connected, the current from the control system electric circuit S passes through the diode D to the ground line PG of the power system electric circuit P. Flow, which ensures the operation of the control system electrical circuit S.

Here, in particular, in the electric device for a vehicle of the present invention, the potential difference detecting means C1 detects the potential difference in the forward direction of the diode D,
When the notification means C2 breaks the downstream side K of the ground line SG of the control system electric circuit S from the point to which the anode of the diode D is connected when the detection result of the potential difference detection means C1 becomes equal to or more than a predetermined value. A determination is made, and an operation for notifying the fact to the outside of the electric device is performed.

That is, when the downstream side K of the ground line SG of the control system electric circuit S to which the anode of the diode D is connected is disconnected, the ground line PG of the power system electric circuit P from the control system electric circuit S via the diode D. A current flows into the diode D, and a forward potential difference appears in the diode D due to this current.
Therefore, in the vehicle electric device of the present invention, it is determined that the ground line SG of the control-system electric circuit S is disconnected when the potential difference in the forward direction of the diode D becomes equal to or more than a predetermined value, and that effect is externalized. Therefore, according to the electric device for a vehicle of the present invention, even if the ground line SG of the control system electric circuit S is disconnected, the operation can be performed. Although the device cannot recognize the occurrence of the disconnection, the driver of the vehicle or the like can surely know the occurrence of the disconnection by the notification operation of the notification means C2. Then, this allows the repair to be performed early.

As the notification operation of the notification means C2, the notification lamp may be turned on to directly notify the driver of the vehicle, or the fact that a disconnection has occurred in a predetermined storage area may be stored. May be. And in the latter case,
When servicing the vehicle, the maintenance staff can know the occurrence of the disconnection by checking whether or not information indicating that the disconnection has occurred is stored in each of the storage areas.

On the other hand, the notification means C2, in addition to the above-described notification operation,
Further, a predetermined process may be executed for fail-safe.

Here, the predetermined predetermined process is appropriately determined according to the configuration of the control system electric circuit S of the vehicle and the like. For example, if the control system electric circuit S detects the battery voltage detection result VB
Is used as a parameter meter for some control, the detection result VB of the control system electric circuit S is
It is estimated that the SG potential is lower than the actual battery voltage by the voltage drop VD because it floats by the voltage drop (VD) of the diode D. Therefore, by adding the voltage drop VD to the detection result VB and using it as a control parameter meter, the control system electric circuit S can exert a normal control function before the ground SG fails. Further, when the detection output of the air-fuel ratio sensor or the like becomes abnormal due to the failure of the ground SG of the control system electric circuit S, and the estimation of the normal value is impossible, the air-fuel ratio sensor is executed based on these detection results. Various controls such as fuel ratio feedback control may be stopped.

Then, if such a process for fail-safe is executed so that a control function that is extremely close to the normal time can be realized, in the conventional device, it is possible to detect that the ground line SG of the control system electric circuit S is disconnected. Further, although it becomes more difficult to recognize, the electric device for a vehicle of the present invention can surely know the occurrence of the disconnection by the notification operation of the notification means C2.

Hereinafter, the present invention will be described in more detail with reference to Examples.

(Embodiment) FIG. 2 is a schematic electric circuit block diagram of a vehicle equipped with the electric device for a vehicle of the embodiment. As shown in the figure, the electric device 10 for a vehicle is roughly composed of a control system electric circuit 20 composed of digital electric elements for executing logical operations and an output circuit 30 which is a power system electric circuit for controlling large electric power. There is.

The control system electric circuit 20 executes, as is known, a CPU 22 that executes a logical operation, a ROMB 24 that stores a program executed by the CPU 22 in a nonvolatile manner, and a temporary storage of information.
It is composed of a RAM 26 and an input / output port 28 that serves as a port for exchanging information with external devices. The input / output port 28 includes a sensor group (sensor 1 to sensor m) for detecting various driving states provided in the vehicle, a battery power supply line + B described later, and its lighting controlled by executing a program described later. Fail notification lamp 40 and output circuit 30
Control line is connected, the detection signal input from the sensor group and the voltage value of the power supply line + B of the battery are converted into a digital signal that can be handled by the CPU 22 and input, and a lighting signal is output to the fail notification lamp 40. Or outputs a control signal to the output circuit 30. Since each constituent electric element of the control system electric circuit 20 which operates in this way is a normal logical operation element, a voltage of low TTL level is required as a voltage source. Then, an automatic voltage regulator that converts the voltage of the vehicle battery 50 into a stable TTL level voltage (hereinafter,
It is called AVR) 60.

The ground G1 of the control system electric circuit 20 is naturally connected to the ground G2 of the AVR60, which is the voltage source, to form the ground GA, which is connected to the wire harness via the connector CA.
It is connected to the ground of battery 50 by WH. As is well known, the ground of the battery 50 is also connected to the body of the vehicle.

On the other hand, another output circuit 30 constituting the electric device 10 for a vehicle is connected to various actuator groups (actuator 1 to actuator n) of the vehicle, and each output circuit 30 is operated in accordance with a control signal input from the input / output port 28 described above. The power supplied to the actuators is adjusted to drive each actuator. Therefore, the output circuit 30 needs to execute control of sufficient electric power to drive each actuator,
Therefore, the voltage from the battery 50 is directly input. Further, since the power to be controlled is large, the ground GB is connected to a system different from the ground GA so as not to adversely affect the control system electric circuit 20 such as noise.

The power supply lines of the control system electric circuit 20 and the output circuit 30 are configured as described above, and the operation thereof can be executed. However, since the ground GA of the control system electric circuit 20 is connected to the battery 50 by the wire harness WH via the connector CA, the connection failure of the connector CA or the wire harness WH is broken (hereinafter, referred to as the ground GA).
There is a possibility of failure), and it is necessary to secure the operation of the control system electric circuit 20 even at this time. Therefore, the diode 70 is connected from the ground GA to the ground GB so that the body of the vehicle can be operated as the ground so that the vehicle can be driven without significantly impairing the control function in the event of such a failure. . Further, an operation amplifier (hereinafter referred to as an OP amplifier) 80 is connected to both ends of the diode 70, and a forward voltage drop of the diode 70 is amplified and input to the input / output port 28.

The electric device for a vehicle 10 of the embodiment configured as described above
Can produce the following effects.

First, also in the vehicle electric device 10 of the embodiment, as described above, the control system electric circuit 20 and the output circuit 30 are grounded.
GA and GB are configured separately, and malfunctions and the like due to noise in the control system electric circuit 20 caused by load fluctuations of the output circuit 30 are avoided, and accurate operation is ensured. Further, when the ground GA fails, a new ground is formed via the diode 70, and the operation of the control system electric circuit 20 is secured.

Further, the vehicle electric device 10 of the present embodiment has the following new effects due to the existence of the OP amplifier 80 which amplifies and detects the forward voltage drop of the diode 70 and the program at the time of ground failure stored in the ROM 24. Play.

Hereinafter, the operation of the vehicular electric apparatus 10 of the embodiment will be described with reference to the flow chart of the program for ground failure shown in FIG.

The program at the time of ground failure in FIG. 3 is forcibly interrupted by the CPU 22 when the detection signal from the OP amplifier 80 is input. Since the OP amplifier 80 detects the forward voltage of the diode 70, the output is normally 0.0 [V], but when the ground GA fails, the control system electric circuit 20 and the AVR60 are forwarded to the diode 70.
Current flows, a voltage drop VD [V] corresponding to the forward characteristic of the diode 70 appears. When this voltage drop VD is input from the input / output port 28, the program is executed at the time of ground failure.

When the process is started, the CPU 22 first reads the accurate value of the forward voltage drop VD (step 100),
Next, the fail notification lamp 40 is turned on to notify the driver of the occurrence of the ground GA failure (step 110), and the fail flag FF indicating the ground GA failure is set to "1" (step 120). Here, the fail flag FF is C
It is used in various control programs executed by PU22 and is provided to instruct to prohibit the future use of sensors and actuators that cannot operate correctly due to ground GA failure. It is a flag. Therefore, the CPU 22, for example, determines the set state of the fail flag FF during execution of various control programs,
When the fail flag FF is in the set state of "1", processing such as substituting the initial value for the detection signal of the predetermined sensor or stopping the processing of the program which requires the operation of the predetermined actuator is executed. Of.

When the setting process of the fail flag FF is completed, next, the quasi-direction voltage drop VD input in the step 100 is added to the voltage value VBf of the power supply line + B of the battery 50 input from the input / output port 28 to newly add. Set as voltage value VB. This is to accurately give the current battery voltage VB in various controls using the battery voltage VB as a parameter meter.

That is, as shown in FIG. 4, various actuators are operating with the negative pole of the battery as the ground, and the battery voltage VB is supplied as it is.
Since the ground GA and the ground GB have the same potential when the ground GA is normal, the battery voltage VBf monitored by the control electric circuit 20 is equal to the supply voltage VB of the actuator as it is.

However, when the ground GA fails, the battery voltage monitored by the control system electric circuit 20 is a value VBf subtracted by the quasi-direction voltage drop VD of the diode 70 if the negative electrode of the battery is used as a reference as shown in the figure. . Therefore, when the ground GA fails, the battery voltage VB applied to the actuator cannot be known unless the forward voltage drop VD of the diode 70 is added to the battery voltage value VBf detected by the control system electric circuit 20. As is well known, various actuators have different characteristics depending on the applied voltage value. For example, the invalid injection time of the fuel injection valve that injects and supplies the fuel to the internal combustion engine becomes longer as the applied voltage decreases. Therefore, the control system electric circuit 20 for controlling these actuators constantly monitors the voltage applied to the actuator and executes the control according to the voltage applied to the actuator. Therefore, the process of step 130 calculates an accurate battery voltage VB so that the control of these actuators does not fail even when the ground GA fails, and this voltage value VB is used to calculate the fuel injection time. Calculations and other various controls are executed.

According to the vehicular electric apparatus of the present embodiment configured as described above, the ground GA and the ground GB are separately configured, and since the diode 70 that connects the ground GA and the ground GB is provided, in the normal state. The highly accurate control of the control system electric circuit 20 can be achieved, and the operation of the control system electric circuit 20 can be ensured and the vehicle operation can be continued even when the ground GA fails.

In particular, since the forward voltage drop of the diode 70 is monitored and the process shown in FIG. 3 is executed according to the result, the driver can be notified of the fail state of the ground GA. Further, it is possible to easily prohibit the use of a sensor that cannot be relied upon when the ground GA fails, an actuator that cannot be used, or the like by determining the set state of the fail flag FF. Further, it becomes possible to continuously and accurately monitor the battery voltage, and the actuator whose operation state is greatly influenced by the battery voltage can be continuously used without any trouble even after the failure of the ground GA.

In the above embodiment, there are sensors and actuators having various characteristics, and an example in which the driving performance of the vehicle is kept high by using these sensors and actuators as much as possible even after the ground GA failure has been described. The present invention is not limited to the embodiment, and may have only a single function of notifying the driver. Further, the detection of the forward voltage drop VD of the diode 70 does not depend on the OP amplifier 80,
Any method such as using a highly sensitive transistor or optically detecting with a photodiode or the like may be adopted.

Effects of the Invention As described in detail above with reference to the embodiments, the electric device for a vehicle according to the present invention can operate even if the ground wire of the control system electric circuit is broken, and it is possible to prevent the disconnection from the functional state. Despite being a device that cannot recognize the occurrence,
The driver of the vehicle or the like can surely know the occurrence of the disconnection by the notification operation of the notification means, and thereby can perform the repair at an early stage.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram showing a basic configuration of an electric device for a vehicle of the present invention, FIG. 2 is a block diagram of an electric circuit of an electric device for a vehicle of an embodiment, and FIG. 3 is a program used in the embodiment. FIG. 4 is an operation explanatory view for explaining the operation of the embodiment. 10 …… Vehicle electric device, 20 …… Control system electric circuit 30 …… Output circuit, 50 …… Battery 70 …… Diode, 80 …… OP amplifier

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A 61-229638 (JP, A) JP-A 62-647 (JP, A) JP-B 63-29662 (JP, B2)

Claims (3)

(57) [Claims] 1. A ground line of a power system electric circuit that requires a large amount of power and a ground line of a control system electric circuit are configured separately, and an anode is connected to the ground line of the control system electric circuit. In a vehicular electric device comprising a diode whose cathode is connected to a ground line of the power system electric circuit, a potential difference detecting means for detecting a forward potential difference of the diode, and a detection result of the potential difference detecting means is a predetermined value or more. When it becomes, it is judged that the downstream side of the ground line of the control system electric circuit is disconnected from the point where the anode of the diode is connected, and a notification is made to notify the outside of the electric device to that effect. An electric device for a vehicle, comprising: 2. The electric device for a vehicle according to claim 1, wherein the notifying means lights a notification lamp. 3. The electric device for a vehicle according to claim 1, wherein the notifying unit stores that a disconnection has occurred in a predetermined storage area.