Vehicle control device

Abstract

To provide a vehicle control device that can further improve safety when a vehicle starts.SOLUTION: A vehicle control device is used in a vehicle mounted with an engine, and comprises a rotation speed detection unit for detecting the engine rotation speed of the engine, and an engine control unit for controlling the amount of fuel injection of the engine. The engine control unit limits the amount of fuel injection in the case where the engine rotation speed detected by the rotation speed detection unit at the time when the vehicle is in an idling state exceeds a predetermined upper limit value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a control device for a vehicle.

Background Art

[0002] In recent years, vehicles have been equipped with a control device for preventing sudden acceleration due to misoperation of the accelerator pedal and the brake pedal.

[0003] For example, Patent Document 1 discloses a vehicle control device that determines whether to enable or disable the depression of the accelerator pedal based on the depression operations of the accelerator pedal and the brake pedal by the driver and the result of sensing the position of the driver's foot, and prevents sudden acceleration due to misoperation.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, even though the accelerator pedal is not depressed during idling, the engine speed may unexpectedly increase (so-called engine surge). If the vehicle is started with the engine speed increased, there is a risk of sudden acceleration unintended by the driver, leading to a decrease in safety.

[0006] The technique disclosed in Patent Document 1 can prevent sudden acceleration due to driver misoperation, but cannot prevent sudden acceleration of the vehicle due to an increase in engine speed.

[0007] Therefore, an object of the present disclosure is to provide a vehicle control device that can further improve the safety during vehicle startup.

Means for Solving the Problem

[0008] This disclosure has been made to solve at least a part of the above-described problems, and can be realized as the following aspects or application examples.

[0009] The vehicle control device according to this application example is a vehicle control device used for a vehicle equipped with an engine, and includes a rotation speed detection unit that detects the engine speed of the engine, and an engine control unit that controls the fuel injection amount of the engine. The engine control unit is characterized in that when the engine speed detected by the rotation speed detection unit becomes equal to or higher than a preset upper limit value during the idling state of the vehicle, the fuel injection amount is restricted.

[0010] By thus presetting the upper limit value of the engine speed during idling and restricting the fuel injection amount when the engine speed detected by the rotation speed detection unit becomes equal to or higher than the upper limit value, a rapid increase in the engine speed during idling can be suppressed. Thereby, a sudden start of the vehicle can be prevented, and the safety during vehicle start can be further improved.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the content described below, and can be arbitrarily modified and implemented without changing the gist thereof. In addition, the drawings used in the description of the embodiments schematically show the constituent members, and partial emphasis, enlargement, reduction, or omission, etc. are performed for better understanding, and there may be cases where the scale, shape, etc. of the constituent members are not accurately represented.

[0013] FIG. 1 is a schematic configuration diagram showing a vehicle 1 equipped with a control device according to an embodiment of the present invention. The vehicle 1 on which the control device of the present embodiment is mounted is a commercial vehicle such as a bus or a truck. As shown in FIG. 1, the vehicle 1 includes an engine (internal combustion engine) 10 as a drive source and an ECU 11 (engine control unit).

[0014] The engine 10 of the present embodiment is a diesel engine and includes a fuel injection valve (not shown) that injects fuel into each cylinder. The fuel injection valve is controlled by the ECU 11 for the fuel injection amount, fuel injection timing, etc.

[0015] The ECU (Electronic Control Unit) 11 is a computer including a central processing unit (CPU), a main storage device (such as ROM and RAM) used for storing control programs and control maps, an input / output device, a timer counter, etc. The ECU 11 is communicably connected to various devices and other control units mounted on the vehicle 1 via a CAN (Control Area Network) which is an in-vehicle communication network, can acquire information from various devices and other control units, and can control various devices based on the acquired information.

[0016] As shown in FIG. 1, the ECU 11 of the present embodiment is communicably connected to an accelerator opening sensor 20, a brake sensor 21, a parking brake 22, a vehicle speed sensor 23, and an engine speed sensor 24.

[0017] The accelerator opening sensor 20 has a function of detecting the depression state of an accelerator pedal (not shown). The accelerator pedal is provided near the driver's seat of the vehicle, and is a pedal for giving an instruction for the output of the vehicle 1 according to the depression operation of the driver on the accelerator pedal.

[0018] The brake sensor 21 has a function of detecting the depression state of a brake pedal (not shown). Specifically, the brake sensor 21 detects the pressure of the brake air according to the depression operation of the driver on the brake pedal, and outputs it to the ECU 11.

[0019] The parking brake 22 is a braking device for maintaining the parked state of the vehicle. The operation part of the parking brake 22 may be a side lever type beside the driver's seat, a foot step type stepped on by foot, a switch type, or the like.

[0020] The vehicle speed sensor 23 has a function of detecting the vehicle speed of the vehicle, and can detect the vehicle speed from the rotational speed of the output shaft (for example, propeller shaft) of the vehicle 1.

[0021] The engine speed sensor 24 (rotation speed detection part) is provided on the outer peripheral part of a flywheel (not shown) of the engine 10, and has a function of detecting the engine speed.

[0022] The ECU 11 of the present embodiment performs engine speed control to prevent the engine speed from rising unexpectedly during idling.

[0023] FIG. 2 is a flowchart showing the control procedure of the control device of the vehicle according to the present embodiment. Hereinafter, the engine speed control during idling executed by the ECU 11 will be described along the flowchart of FIG. 2.

[0024] First, as step S1, the ECU 11 determines whether the permission condition for engine speed control is satisfied. The permission condition for engine speed control is a condition for determining that the vehicle 1 is in an idling state and the brake pedal is depressed. For example, the condition that the depression amount of the accelerator pedal from the accelerator opening sensor 20 is zero, the condition that the parking brake 22 is ON, the condition that the vehicle speed from the vehicle speed sensor 23 is zero, and the condition that the depression amount of the brake pedal from the brake sensor 21 is not zero are respectively detected states where the permission condition is satisfied, that is, the state where it is determined that the vehicle is in an idling state and the brake pedal is depressed. Note that the state where the permission condition in step S1 is satisfied may not include the condition that the depression amount of the accelerator pedal is zero. For example, even in a state where both the accelerator pedal and the brake pedal are depressed, the state where the permission condition in step S1 is satisfied may be determined to be true (Yes).

[0025] If the determination result in step S1 is true (Yes), that is, if the permission condition is satisfied, the ECU 11 proceeds to the next step S2. On the other hand, if the determination result in step S1 is false (No), that is, if the permission condition is not satisfied (for example, when the vehicle is running), the ECU 11 returns from the routine.

[0026] As step S2, the ECU 11 determines whether the engine speed is equal to or less than a preset upper limit value A1. The upper limit value A1 is set to a rotation speed such that sudden acceleration does not occur when the accelerator pedal is depressed from the idling state. For example, in the case of a commercial vehicle equipped with a diesel engine such as a bus or a truck as in this embodiment, it is preferably set to a predetermined rotation speed within the range of 1200 to 2000 rpm.

[0027] If the determination result in step S2 is true (YES), that is, when the detected engine speed is equal to or higher than the upper limit value A1, the ECU11 proceeds to the next step S3. On the other hand, if the determination result in step S2 is false (NO), that is, when the detected engine speed is less than the upper limit value A1, the ECU11 returns from the routine.

[0028] As step S3, the ECU11 determines whether the duration during which the engine speed has been equal to or higher than the upper limit value A1 (continuous duration) is longer than the reference time T1. The reference time T1 can be set in advance in the ECU11 and is set to the time when the engine speed stabilizes during idling.

[0029] If the determination result in step S3 is true (YES), that is, when the continuous duration during which the detected engine speed is equal to or higher than the upper limit value A1 is longer than the reference time T1, the ECU11 proceeds to the next step S4. On the other hand, if the determination result in step S3 is false (NO), that is, when the continuous duration during which the detected engine speed is equal to or higher than the upper limit value A1 is within the reference time T1, the ECU11 returns from the routine.

[0030] As step S4, based on the determination results from step S1 to S3, the ECU11 estimates that there is an unexpected increase in the engine speed, that is, a state leading to a sudden acceleration of the vehicle 1, and forcibly limits the fuel injection amount to the fuel injection valve. Then, the ECU11 warns the driver that the engine 10 may rotate at a high speed and cause a sudden acceleration, for example, by lighting a warning lamp on the meter panel in front of the driver's seat of the vehicle 1 and sounding a warning sound. The limitation of the fuel injection amount may be to reduce a predetermined amount from the fuel injection amount at that time, or to suppress it to a predetermined fuel injection amount set in advance.

[0031] The restricted state of the fuel injection amount is released when the ECU 11 returns from this routine, the permission condition is not satisfied (step S1 is false (No)), the engine speed is less than the upper limit value A1 (the determination result in step S2 is false (No)), or by turning off the starter key (not shown).

[0032] As described above, in the vehicle control device according to the present embodiment, the upper limit value A1 of the engine speed during idling is set in advance, and when the engine speed detected by the engine speed sensor 24 becomes equal to or higher than the upper limit value A1, the fuel injection amount is restricted, thereby suppressing a rapid increase in the engine speed during idling. This can prevent the vehicle from suddenly starting and further improve the safety when the vehicle starts.

[0033] With the above, the description of the embodiment of the present invention is completed, but the form of the present invention is not limited to this embodiment.

[0034] The vehicle in the above embodiment is a commercial vehicle equipped with a diesel engine, but it is also applicable to other vehicles. For example, the engine may be a gasoline engine, a passenger car, or a hybrid vehicle equipped with a motor in addition to the engine as a drive source.

[0035] Also, in the above embodiment, the ECU 11 performs engine speed control based on information from the accelerator opening sensor 20, the brake sensor 21, the parking brake 22, the vehicle speed sensor 23, and the engine speed sensor 24, but it may be controlled by one or more other control units, or may be controlled based on information from other sensors.

[0036] Also, in the above embodiment, in step S4, the driver is warned by turning on the warning lamp on the meter panel and sounding a warning sound, but other warning methods may be used. For example, a warning message may be displayed on the display screen of the car navigation.

[0037] Also, although the upper limit value A1 of the engine speed in the above embodiment has been described as one fixed value, the upper limit value A1 is not limited to a fixed value and may be a variable value that varies according to the state of the vehicle in which an increase in the engine speed can be expected. For example, when Vehicle 1 is equipped with an exhaust gas purification device including a diesel particulate filter (DPF), when increasing the fuel injection amount for DPF regeneration during idling, it may be switched to an upper limit value A2 set to a higher engine speed than the normal upper limit value A1. In addition, other states of the vehicle in which an increase in the engine speed can be expected include engine warming up and operating the compressor of the air conditioner, etc., and different upper limit values may be set according to each state. It is preferable to store these upper limit values in a storage unit that can be read by the ECU.

[0038] Also, the upper limit value A1 in step S2 may be determined using, in addition to or instead of the engine speed, the fuel injection amount instruction value (a value corresponding to a sudden start at the time of starting) instructed by the ECU11.

Explanation of Reference Numerals

[0039] 1 Vehicle 10 Engine 11 ECU (Engine Control Unit) 20 Accelerator Opening Sensor 21 Brake Sensor 22 Parking Brake 23 Vehicle Speed Sensor 24 Engine Speed Sensor (Rotation Speed Detection Unit)

Claims

【Claim 1】 A vehicle control device used in a vehicle equipped with an engine, comprising a rotational speed detection unit that detects the rotational speed of the engine, and an engine control unit that controls the fuel injection amount of the engine, wherein the engine control unit restricts the fuel injection amount when the engine rotational speed detected by the rotational speed detection unit becomes equal to or higher than a preset upper limit value during an idling state of the vehicle.

Images