Vehicular control device

Abstract

To provide a vehicular control device which can prevent engine stall caused by the sudden drop of a battery voltage due to sudden failure of the battery and perform an abnormality diagnosis of the battery.SOLUTION: An abnormality diagnosis part of a vehicular control device stops, when engine speed of an engine is larger than a prescribed rotation number (YES at Step S6), electricity generation of a generator (Step S7), and diagnoses abnormality of a battery based on a voltage drop ratio of the battery after the electricity generation is stopped (Step S9). The prescribed rotation number is a value that is larger than the lower limit of the engine speed where the engine can rotate by itself through fuel injection. The abnormality diagnosis part re-starts, when the battery is diagnosed as abnormality through an abnormality diagnosis behavior, the electricity generation of the generator and prohibits the electricity generation of the generator from being stopped (Step S10). The abnormality diagnosis part notifies a user of a fact that the battery is abnormal, when the battery is diagnosed as abnormality (Step S11).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] Patent Document 1 describes a technique for measuring the amount of voltage drop after leaving a battery for a predetermined time, and determining that the battery is defective if the amount of voltage drop is equal to or greater than a predetermined value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-251538 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the conventional technology described in Patent Document 1 determines whether a battery has an abnormality in the early stages after its manufacture, and does not take into consideration the possibility of a sudden abnormality occurring after the battery has been mounted on a vehicle and continuously used after manufacture. If a battery continues to be mounted on a vehicle and used continuously, factors such as vibrations may place a load on the battery's components, causing a sudden failure and a drop in battery voltage. If the battery voltage drops due to a failure, stopping the generator to perform a battery abnormality diagnosis could result in an unstable power supply and potentially cause the engine to stall. Therefore, it was necessary to appropriately set the conditions for executing the battery abnormality diagnosis.

[0005] The present invention has been made in light of the above-mentioned circumstances, and aims to provide a vehicle control device that can diagnose battery abnormalities while preventing engine stalls caused by a sudden drop in battery voltage due to a sudden battery failure. [Means for solving the problem]

[0006] The present invention is a vehicle control device that is mounted on a vehicle that has an engine, a battery that supplies power to electrical equipment, and a generator that generates electricity using the power of the engine and supplies the generated electricity to the electrical equipment and the battery, and is equipped with an abnormality diagnosis unit that stops the generator from generating electricity and performs an abnormality diagnosis operation to diagnose the presence or absence of an abnormality in the battery based on the rate of voltage drop of the battery after power generation has stopped, and is characterized in that the abnormality diagnosis unit performs the abnormality diagnosis operation on the condition that the engine speed of the engine is greater than a predetermined speed. [Effects of the Invention]

[0007] As described above, according to the present invention, a vehicle control device can be provided that can diagnose battery abnormalities while preventing engine stalls caused by a sudden drop in battery voltage due to a sudden battery failure. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing the configuration of a vehicle equipped with a vehicle control device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart illustrating an abnormality diagnosis operation of the vehicle control device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] A vehicle control device according to one embodiment of the present invention is mounted on a vehicle including an engine, a battery that supplies power to electrical components, and a generator that generates power using power from the engine and supplies the generated power to the electrical components and the battery, and includes an abnormality diagnosis unit that performs an abnormality diagnosis operation to stop power generation of the generator and diagnose whether or not there is an abnormality in the battery based on a rate of voltage drop in the battery after power generation has been stopped, wherein the abnormality diagnosis unit performs the abnormality diagnosis operation on the condition that the engine speed is greater than a predetermined speed. As a result, the vehicle control device according to one embodiment of the present invention can diagnose an abnormality in the battery while preventing an engine stall caused by a sudden drop in battery voltage due to a sudden battery failure. [Example]

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle control device according to an embodiment of the present invention will now be described with reference to the accompanying drawings, in which: Figures 1 and 2 are diagrams illustrating a vehicle control device according to an embodiment of the present invention.

[0011] 1, a vehicle 1 includes an engine 2, a battery (referred to as a lead battery in the figure) 4 that supplies power to electrical components 11 and 12, a generator 3 that generates power using the power of the engine 2 and supplies the generated power to the electrical components 11 and 12 and the battery 4, and an ECU 10. The generator 3, the battery 4, the electrical components 11 and 12, and the ECU 10 are electrically connected to one another.

[0012] The vehicle 1 is provided with a current sensor 5 that measures the current flowing through the battery 4. A detection signal (battery current) of the current sensor 5 is transmitted to the ECU 10.

[0013] The vehicle 1 is provided with a voltage sensor 6 that measures the voltage applied from the generator 3 to the battery 4. A detection signal of the voltage sensor 6 is transmitted to the ECU .

[0014] The vehicle 1 is equipped with a charge amount sensor 7 that measures the amount of charge charged from the generator 3 to the battery 4. The charge amount sensor 7 calculates the amount of charge by integrating the value of the current flowing through the battery 4 while the generator 3 is generating electricity. A detection signal from the charge amount sensor 7 is sent to the ECU 10.

[0015] The vehicle 1 is provided with an engine speed sensor 8 that detects the rotation speed of the engine 2 as the engine rotation speed. A detection signal of the engine speed sensor 8 is transmitted to the ECU 10.

[0016] The vehicle 1 is provided with an electric load sensor 9 that detects an electric load. A detection signal from the electric load sensor 9 is transmitted to the ECU 10.

[0017] The ECU 10 is equipped with an abnormality diagnosis unit 10A that performs an abnormality diagnosis operation. The abnormality diagnosis operation is an operation that stops power generation by the generator 3 and diagnoses whether or not there is an abnormality in the battery 4 based on the voltage drop rate of the battery 4 after power generation has stopped. Power generation by the generator 3 is stopped because while power generation is occurring, the voltage does not drop and it is not possible to diagnose the battery 4. The voltage drop rate refers to the amount of voltage drop per unit time. The abnormality diagnosis unit 10A determines that the battery 4 is abnormal if the voltage drop rate is greater than a predetermined judgment threshold.

[0018] In this embodiment, an abnormality in the battery 4 refers to a state in which the battery 4 is still capable of supplying power to the ECU 10 and devices with small electrical loads, such as injectors and spark plugs (not shown), but its performance has deteriorated to the point where it is unable to supply power to devices with large electrical loads, such as a starting device (not shown) and a motor generator (not shown). An abnormality in the battery 4 also refers to a state in which, although charging is possible, stopping charging causes a short circuit, resulting in unintended discharge, or the voltage drops suddenly due to only a small amount of SOC being recovered. In the following description, an abnormality in the battery 4 is also referred to as a malfunction.

[0019] The ECU 10 is composed of a computer unit having a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), a flash memory for storing backup data, and an input port and an output port. The ROM of the computer unit stores various constants, maps, and other data, as well as programs for causing the computer unit to function as the ECU 10. That is, the CPU uses the RAM as a work area to execute the programs stored in the ROM, causing the computer unit to function as the ECU 10 in this embodiment.

[0020] Here, failures of the battery 4 include failures in which performance drops below a certain level due to gradual deterioration over time, and failures in which irreversible performance degradation is suddenly caused by damage to the internal electrodes due to vibration, etc. Since it is difficult to predict when the latter sudden failure of the battery 4 will occur, it is desirable to periodically perform an abnormality diagnosis operation at short intervals to check for the presence or absence of a failure in the battery 4.

[0021] On the other hand, if an abnormality diagnosis operation involving stopping the generator 3 is performed while the battery 4 is faulty, the power supply from the faulty battery 4 to the electrical components 11, 12 will be unstable, which may cause the engine speed to drop significantly before the abnormality diagnosis operation is completed, resulting in an engine stall. Therefore, the abnormality diagnosis unit 10A is configured to perform the abnormality diagnosis operation under conditions that are less likely to cause an engine stall.

[0022] The abnormality diagnosing unit 10A performs an abnormality diagnosing operation on the condition that the engine speed of the engine 2 is greater than a predetermined speed.

[0023] The predetermined rotation speed is set to a value greater than the lower limit of the engine rotation speed at which the engine 2 can rotate autonomously through fuel injection. Even when fuel injection to the engine 2 is not being performed due to fuel cutoff during deceleration, if the engine rotation speed is greater than the predetermined rotation speed, there is no risk of the engine stalling and the engine can rotate autonomously once fuel injection is resumed, so the abnormality diagnosis unit 10A performs the abnormality diagnosis operation. It is desirable to perform the abnormality diagnosis operation more frequently. It is desirable to complete the abnormality diagnosis operation just before the engine 2 is stopped by idling stop control or by turning off the ignition switch.

[0024] When the abnormality diagnosis unit 10A diagnoses that the battery 4 is abnormal through the abnormality diagnosis operation, it restarts the power generation of the generator 3 and prohibits the power generation of the generator 3 from being stopped.

[0025] The electrical equipment 11 includes electrical equipment for driving that contributes to driving, such as a fuel injection system and an ignition system. The electrical equipment 11 also includes the ECU 10. The electrical equipment 12 includes electrical equipment for non-driving that does not contribute to driving, such as a navigation system, an audio system, and an air conditioning system.

[0026] When the abnormality diagnosis unit 10A diagnoses that the battery 4 has an abnormality through the abnormality diagnosis operation, it stops the supply of power to the electrical equipment 12 that is a non-driving electrical equipment.

[0027] When the abnormality diagnosis unit 10A diagnoses that the battery 4 is abnormal as a result of the abnormality diagnosis operation, it notifies that the battery 4 is abnormal.

[0028] The abnormality diagnosis operation by the abnormality diagnosis section 10A of the ECU 10 will be described with reference to the flowchart shown in FIG.

[0029] First, the abnormality diagnosis unit 10A checks the electric load of the vehicle 1 (step S1).

[0030] Next, the abnormality diagnosis unit 10A determines whether the electrical load is low (step S2). Here, the abnormality diagnosis unit 10A targets the electrical equipment 12, which is made up of non-driving electrical equipment that does not contribute to driving, and determines that the electrical load is low if the electrical load is less than a predetermined threshold value. In other words, this prevents the state of the battery 4 from fluctuating greatly due to variations in the power consumption of non-driving electrical equipment that does not contribute to driving. Alternatively, correction may be made taking these power consumptions into account. For example, if the power consumption is high, this amount may be subtracted from the voltage drop of the battery 4. If the electrical load is not less than the predetermined electrical load (NO in step S2), the abnormality diagnosis unit 10A returns to step S1.

[0031] If the electric load is less than the predetermined electric load (YES in step S2), the abnormality diagnosis unit 10A calculates the charge amount of the battery 4 based on the battery current (step S3).

[0032] Next, the abnormality diagnosis unit 10A determines whether the charge amount of the battery 4 is greater than a predetermined determination threshold (step S4). If the charge amount of the battery 4 is not greater than the predetermined determination threshold (NO in step S4), the abnormality diagnosis unit 10A returns to step S1.

[0033] If the charge amount of the battery 4 is greater than the predetermined determination threshold (YES in step S4), the abnormality diagnosis unit 10A measures the engine rotation speed (step S5).

[0034] Next, the abnormality diagnosis unit 10A determines whether the engine speed is greater than a predetermined threshold value (step S6). If the engine speed is not greater than the predetermined threshold value (NO in step S6), the abnormality diagnosis unit 10A returns to step S1.

[0035] If the engine speed is greater than the predetermined determination threshold (YES in step S6), the abnormality diagnosis unit 10A temporarily suspends power generation by the generator 3 (step S7) and calculates the battery voltage drop rate (step S8).

[0036] Next, the abnormality diagnosis unit 10A determines whether the battery voltage drop rate is greater than a predetermined determination threshold (step S9). If the battery voltage drop rate is not greater than the predetermined determination threshold (NO in step S9), the abnormality diagnosis unit 10A returns to step S1.

[0037] If the battery voltage drop rate is greater than a predetermined judgment threshold (YES in step S9), the abnormality diagnosis unit 10A determines that the battery 4 is abnormal, and forces the generator 3 to generate electricity to ensure power (step S10) in order to prevent power from being cut off to electrical equipment such as the abnormality diagnosis unit 10A due to an abnormality in the battery 4.

[0038] Next, the abnormality diagnosis unit 10A notifies the user that the battery 4 is abnormal (step S11), and ends the current operation. One possible form of notification is to display a message urging the user to replace the battery 4 because it is abnormal. The abnormality diagnosis unit 10 may also determine subsequent processing depending on the battery voltage drop rate. For example, if the battery voltage drop rate is small, the abnormality diagnosis unit 10 may notify the user and cut off power not necessary for driving, and if the battery voltage drop rate is large, may not stop power generation.

[0039] As described above, in this embodiment, the abnormality diagnosis unit 10A performs an abnormality diagnosis operation to stop power generation by the generator 3 and diagnose whether or not there is an abnormality in the battery 4 based on the voltage drop rate of the battery 4 after power generation has stopped. The abnormality diagnosis unit 10A performs the abnormality diagnosis operation on the condition that the engine speed of the engine 2 is greater than a predetermined speed.

[0040] As a result, when the engine speed is higher than the predetermined speed, even if the power supply capacity of the battery 4 is reduced due to a sudden failure of the battery 4, the engine speed will not decrease to the extent that it would lead to an engine stall while the abnormality diagnosis operation is being performed, thereby preventing engine stall. Furthermore, when the engine speed is higher than the predetermined speed, there is no need to operate the starter or motor with electric power to rotate the engine 2 in order to prevent engine stall, so the abnormality diagnosis operation can be performed without relying on the power supply capacity of the battery 4 and the generator 3. As a result, it is possible to perform an abnormality diagnosis of the battery 4 while preventing engine stall due to a sudden drop in battery voltage caused by a sudden failure of the battery 4.

[0041] In this embodiment, the predetermined rotation speed is set to a value greater than the lower limit of the engine rotation speed at which the engine 2 can rotate autonomously by fuel injection.

[0042] As a result, the abnormality diagnosis operation is performed while the engine 2 is capable of self-sustaining rotation due to fuel injection, thereby reliably preventing engine stall during the abnormality diagnosis operation. Furthermore, even if the engine 2 cannot be cranked by the starting device due to a decrease in power supply capacity, the engine 2 can continue to operate using only fuel injection, thereby reliably preventing engine stall.

[0043] Furthermore, in this embodiment, when the abnormality diagnosis unit 10A diagnoses that the battery 4 is abnormal through the abnormality diagnosis operation, it restarts the power generation of the generator 3 and prohibits the power generation of the generator 3 from being stopped.

[0044] This allows the generator 3 to continue supplying power to the electrical components 11 and 12 in place of the battery 4, whose power supply capacity has decreased due to the occurrence of an abnormality. Also, engine stalls due to insufficient power supply can be prevented, allowing the vehicle 1 to continue traveling.

[0045] In addition, in this embodiment, the electrical equipment 12 consists of non-driving electrical equipment that does not contribute to driving, and the abnormality diagnosis unit 10A stops the supply of power to the electrical equipment 12 when it diagnoses that the battery 4 is abnormal through the abnormality diagnosis operation.

[0046] Furthermore, in this embodiment, when the abnormality diagnosis unit 10A diagnoses that the battery 4 is abnormal as a result of the abnormality diagnosis operation, it notifies that the battery 4 is abnormal.

[0047] While an embodiment of the present invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made thereto without departing from the scope of the present invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0048] 1 vehicle 2 engines 3. Generator 4 Battery 10 ECU (vehicle control unit) 10A Abnormality diagnosis section 12 Electrical equipment (non-driving electrical equipment)

Claims

1. The engine and a battery that supplies power to the electrical equipment; a generator that generates electricity using power from the engine and supplies the generated electricity to the electrical equipment and the battery, a vehicle control device including an abnormality diagnosis unit that performs an abnormality diagnosis operation of stopping power generation by the generator and diagnosing whether or not there is an abnormality in the battery based on a voltage drop rate of the battery after power generation has been stopped, The vehicle control device is characterized in that the abnormality diagnosis unit performs the abnormality diagnosis operation on condition that the engine speed of the engine is greater than a predetermined speed.

2. 2. The vehicle control device according to claim 1, wherein the predetermined rotation speed is set to a value greater than a lower limit of the engine rotation speed at which the engine can rotate autonomously by fuel injection.

3. The abnormality diagnosis unit 3. The vehicle control device according to claim 1, wherein when the abnormality diagnosis operation diagnoses that the battery is abnormal, the generator resumes power generation and prohibits the generator from stopping power generation.

4. The electrical equipment includes non-driving electrical equipment that does not contribute to driving, The abnormality diagnosis unit 3. The vehicle control device according to claim 1, wherein when the abnormality diagnosis operation diagnoses that the battery is abnormal, the power supply to the non-driving electrical equipment is stopped.

5. The abnormality diagnosis unit 3. The vehicle control device according to claim 1, wherein when the abnormality diagnosis operation diagnoses that the battery is abnormal, the vehicle control device notifies the user that the battery is abnormal.

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