Vehicle control devices

Abstract

To enhance fuel economy through improving idling stop continuity.SOLUTION: A vehicle control device executes automatic stop control of an engine 3 when a predetermined engine stop condition is met, and automatic start-up control of the engine 3 when a predetermined engine restart condition is met while idling stop control is in execution. In the vehicle control device, when negative pressure of a brake booster 14 becomes lower than a normal drive threshold, drive control of a pump 13a of a brake booster 14 is executed, while the idling stop control is in execution, within a range in which an engine restart condition related to consumption current of a vehicle 1 is not met. Thus, the vehicle control device can prevent the negative pressure of the brake booster 14 from becoming lower than a threshold related to the restart condition of the engine 3. Also, driving of the pump 13a can prevent the consumption current of the vehicle 1 from exceeding the threshold related to the restart condition of the engine 3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vehicle control device including control means for stopping an operating engine when a predetermined engine automatic stop condition is satisfied, and automatically restarting a stopped engine when a predetermined engine restart condition is satisfied.

Background Art

[0002] Conventionally, a vehicle has been proposed that automatically stops the idling of an engine when a predetermined idling stop start condition is satisfied (see, for example, Patent Document 1). Here, as the predetermined idling stop start conditions, (i) the vehicle is stopped, (ii) the battery capacity is equal to or greater than a predetermined amount, (iii) the temperature of the engine cooling water is equal to or higher than a predetermined value, (iv) the difference between the set temperature of the air conditioner and the temperature inside the vehicle cabin is equal to or less than a predetermined value, etc. are exemplified as all conditions to be satisfied.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a vehicle, a brake booster for assisting the operating force of the brake pedal is mounted. However, since the brake booster uses engine negative pressure, there is a possibility that the engine negative pressure may decrease and the desired braking force may not be obtained when the engine is stopped or at low engine speeds. Therefore, when the engine negative pressure decreases, there is an electric negative pressure pump system (EVP system) that supplies negative pressure to the brake booster with an electric pump to compensate for the decrease.

[0005] In vehicles equipped with an electric vacuum pump system for idle stop systems, if the vacuum pressure in the brake booster falls below a threshold while the engine is idled, the electric vacuum pump is activated to raise the vacuum pressure in the brake booster. In addition, in idle stop vehicles, the engine automatically restarts when certain conditions for engine restart are met during idle stop. In some cases, one of these conditions is that the vehicle's current consumption exceeds a threshold. In this case, if the electric vacuum pump is activated during idle stop, the current consumption will exceed the threshold, causing the idle stop system to be deactivated and reducing the efficiency of fuel efficiency improvement.

[0006] This invention was made in view of the above-mentioned problems, and aims to improve fuel efficiency by improving the continuity of idle stop. [Means for solving the problem]

[0007] To achieve the above objective, the vehicle control device of the present invention stops an operating engine when a predetermined automatic engine stop condition is met, and automatically restarts a stopped engine when a predetermined engine restart condition is met, comprising: a brake assist means that assists the brakes using engine negative pressure; and a negative pressure assist means that supplies auxiliary negative pressure to the brake assist means by controlling the drive of a pump, wherein the predetermined engine restart condition is the vehicle's current consumption including the current required to drive the pump. The aforementioned engine restart conditions Including exceeding a threshold, the negative pressure assisting means supplies auxiliary negative pressure to the brake assisting means when the engine is automatically stopped, Threshold for engine restart conditions When it exceeds the limit, the pump's operation is disabled, and the Threshold for engine restart conditions The pump is driven when the value does not exceed (Claim 1).

[0008] Furthermore, the pump may be an electrically driven negative pressure pump (Claim 2).

[0009] Furthermore, the negative pressure assisting means ensures that even when the pump is driven, the vehicle's current consumption is... Conditions for restarting the engine The pump may be driven if it is determined that the threshold value is not exceeded (Claim 3).

[0010] Furthermore, when the negative pressure assisting means supplies auxiliary negative pressure to the brake assisting means while the engine is automatically stopped, the current consumption of the vehicle when the pump is driven is the Conditions for restarting the engine The on / off cycle of the voltage applied to the pump is adjusted so as not to exceed a threshold (Claim 4). [Effects of the Invention]

[0011] According to the invention of claim 1, when the negative pressure assist means supplies auxiliary negative pressure to the brake assist means while the engine is automatically stopped (idling stop state), the pump is driven within a range in which the vehicle's current consumption does not exceed the threshold required for engine restart, so that when supplying auxiliary negative pressure to the brake assist means the vehicle's current consumption is Conditions for restarting the engine This prevents the idle stop state from being deactivated when a threshold is exceeded, improving the continuity of the idle stop function. Furthermore, improved idle stop continuity leads to improved fuel efficiency.

[0012] According to the invention of claim 2, by making the pump an electric vacuum pump, it becomes easier to adjust the vehicle's current consumption when supplying auxiliary vacuum to the brake assist means.

[0013] According to the invention of claim 3, when the negative pressure assist means is driven, the vehicle's current consumption is Conditions for restarting the engine If the engine restarts after exceeding a threshold, the pump will not be driven, thus reliably preventing engine restarts based on pump operation.

[0014] According to the invention of claim 4, while supplying auxiliary negative pressure to the brake assist means, the continuity of the idle stop can be improved, and the fuel efficiency of the vehicle is improved. [Brief explanation of the drawing]

[0015] [Figure 1] It is a block diagram of an embodiment of a vehicle control device of the present invention. [Figure 2] It is a diagram comparing the timing charts of each parameter when the brake is depressed again during idling stop after stopping with a conventional timing chart.

Embodiments for Carrying Out the Invention

[0016] Next, in order to explain the present invention in more detail, an embodiment when the present invention is applied to an idling stop vehicle will be described in detail with reference to FIGS. 1 and 2.

[0017] FIG. 1 shows a block configuration of a vehicle control device provided in an idling stop vehicle 1 (sometimes referred to as vehicle 1). The idling stop vehicle 1 is provided with a single relatively small-capacity 12V lead battery 2 as a power source in order to achieve weight reduction, size reduction, etc. The negative terminal of this battery 2 is connected to the vehicle body of the idling stop vehicle 1 and grounded. A current sensor (not shown) is connected to the battery 2, and the current consumption of the vehicle 1 is measured at a predetermined cycle (for example, 10 ms).

[0018] In FIG. 1, 3 is an engine of the idling stop vehicle 1, 4 is a CVT on the transmission side of the engine 3, and a torque converter (including a lock-up clutch mechanism) 5 is interposed between the engine 3.

[0019] 6 is a starter for starting the engine 3, and is supplied with power from the battery 2 via a relay 7. 9 is a generator with a motor function (hereinafter referred to as ISG (Integrated Starter Generator)) to which the rotational force of the engine 3 is transmitted via a belt 10. During running, it charges the battery 2 with power generation output, and operates as a motor under predetermined conditions to generate the driving force for running of the idling stop vehicle 1.

[0020] Relay 7 has a relay coil 7a and a relay switch 7b. When current flows through the relay coil 7a, the relay switch 7b turns ON, the starter 6 is powered from the battery 2, and the engine 3 starts. Also, when the energization of the relay coil 7a stops, the relay switch 7b turns OFF and the power supply to the starter 6 is stopped.

[0021] 11 is an integrated control ECU in which an EFI control unit that calculates a required torque based on the accelerator opening detected by an accelerator sensor (not shown) and controls the fuel injection amount, intake air amount, ignition timing, etc. of the engine 3 to output this required torque, an idling stop control unit that controls idling stop control, a CVT control unit that controls CVT control, an ABS / VSC control unit that prevents skidding and spinning, and an EVP control unit that controls the drive of the pump 13a (negative pressure pump) of the EVP unit 13 are integrated. In addition, there are an engine ECU that controls engine control and an ISG ECU that controls the ISG, etc., which are each omitted from the drawing, and each ECU is formed by a microcomputer or the like and exchanges information via a communication bus (not shown) such as CAN.

[0022] The integrated control ECU 11 includes a first driver IC 11a connected to one end of the relay coil 7a and functioning as a switch for connecting or disconnecting the one end to the battery 2, a second driver IC 11b connected to the other end of the relay coil 7a and functioning as a switch for grounding or not grounding the other end, and a CPU 11c that controls these ICs 11a, 11b and other controls, and performs controls such as restarting the engine 3 after idling stop described later and driving the pump 13a of the EVP unit 13 to supplementarily supply negative pressure to the brake booster 14.

[0023] The brake booster 14 assists the operating force of the brake pedal 19 and consists of a constant pressure chamber (not shown) that stores engine negative pressure generated by the operation of the engine 3, and a variable pressure chamber (not shown) that stores air at a higher pressure than the engine negative pressure. The brake booster 14 is connected to a master cylinder 15 which is connected to the reservoir tank of the brake system. Brake fluid (brake oil) is stored in the reservoir tank. A negative pressure sensor 20 is also provided in the constant pressure chamber of the brake booster 14 and detects the pressure in the constant pressure chamber as the booster negative pressure. The detection signal from the negative pressure sensor 20 is output to the integrated control ECU 11. The pump 13a of the EVP unit 13 is connected to the constant pressure chamber of the brake booster 14.

[0024] The EVP unit 13 supplies negative pressure to compensate when the negative pressure value in the constant pressure chamber of the brake booster 14 decreases, and includes a pump 13a. The pump 13a is, for example, an electric negative pressure pump, which, when driven, draws gas from the constant pressure chamber of the brake booster 14, thereby creating a negative pressure in the constant pressure chamber that is lower than atmospheric pressure (supplying negative pressure). In this embodiment, the EVP unit 13 and the integrated control ECU 11 are electrically connected, and the drive of the pump 13a is controlled by the CPU 11c of the integrated control ECU 11.

[0025] (Idling stop control) Here, we will explain the general control and operation of the idle stop vehicle 1. When the driver starts the engine 3, if the ignition (IG) key switch 17 is turned ON (engine start command) while the shift lever (not shown) is in the P or N position, the signal from the IG key switch 17 is input to the CPU 11c of the integrated control ECU 11. Based on this input, the CPU 11c instantly energizes the relay 7 and turns it ON. This supplies power from the battery 2 to the starter 6, starting the starter 6 and starting the stopped engine 3 (initial start).

[0026] Once engine 3 starts and battery 2 is fully charged by the ISG's generated power, the CPU 11c of the integrated control ECU 11 performs idle stop control until engine 3 stops when the IG key switch 17 is turned off.

[0027] The CPU 11c of the integrated control ECU 11 receives input such as vehicle speed information from the vehicle speed sensor 8, shift position information from the shift range switch 16, and negative pressure information from the negative pressure sensor 20. It also receives information about the engine 3, such as engine speed and coolant temperature, as well as information about the battery 2, such as current and temperature, master cylinder pressure, lock-up clutch information, and information about various switches inside the vehicle, such as the stop lamp switch and courtesy light switch, via the communication bus.

[0028] Based on this information, the CPU 11c of the integrated control ECU 11 during idle stop control commands the engine ECU to stop the engine when predetermined engine stop conditions are met, and the engine ECU automatically stops the engine 3 by restricting the fuel throttle, etc. Here, predetermined engine stop conditions are, for example, when the driver presses the brake pedal 19 in accordance with a red traffic light, etc., and the master cylinder pressure is above a predetermined pressing pressure (the amount the brake pedal is pressed is above a predetermined value), and for example, the stop lamp is lit and the vehicle 1 has decelerated to a predetermined speed (for example, 9 km / h or less).

[0029] Whether the master cylinder pressure is above a predetermined depression pressure can be determined, for example, based on the detection value of a brake pedal position sensor (not shown) that detects the position of the brake pedal. Furthermore, whether the vehicle 1 has decelerated to a predetermined speed can be determined, for example, based on the output value from the vehicle speed sensor 8.

[0030] Next, if the predetermined engine restart conditions are met during idle stop, the CPU 11c of the integrated control ECU 11 momentarily energizes the relay 7 to turn it on, supplies power from the battery 2 to the starter 6 to start the starter 6, and automatically restarts the stopped engine 3. The specified engine restart conditions are, for example, (i) When the driver releases the brake pedal 19 and the amount of pressure applied to the brake pedal 19 falls below a predetermined threshold (ii) When the shift position information from the shift range switch 16 changes from "D range" or "N range" to "P range (parking range)" (iii) When the shift position information from the shift range switch 16 changes to "R range (reverse range)" (iv) When the accelerator pedal is pressed (when the amount of pressure on the accelerator pedal is greater than or equal to a predetermined value) (v) When the current consumption is greater than or equal to a predetermined value (vi) When the air conditioner is in use and the difference between the set temperature and the temperature inside the car becomes large. (vii) When the defroster switch is turned ON (viii) When the driver unbuckles their seatbelt (ix) When steering input is detected (x) When the pressure in the constant pressure chamber of the brake booster is above a predetermined value. If any of (i) to (x) is true, the CPU 11c of the integrated control ECU 11 performs automatic start control (engine restart control) of the engine 3.

[0031] (Negative pressure assistance by an electric vacuum pump) When idle stop control is not in operation, the CPU 11c of the integrated control ECU 11 controls the operation of the pump 13a of the EVP unit 13 when the pressure in the constant pressure chamber of the brake booster 14 becomes higher than a predetermined threshold (normal drive threshold: EVP ON threshold in Figure 2).

[0032] However, when idle stop control is in operation, the CPU 11c of the integrated control ECU 11 determines whether or not to drive the pump 13a of the EVP unit 13 when the pressure in the constant pressure chamber of the brake booster 14 rises above a predetermined threshold (normal drive threshold: EVP ON threshold in Figure 2), and then drives the pump 13a. Here, "rising above the normal drive threshold" means approaching atmospheric pressure from that threshold. The normal drive threshold is preset based on experiments within the pressure range between the pressure that can be reached when the constant pressure chamber is vacuumed by the pump 13a (limit negative pressure) and the threshold required to restart the engine.

[0033] Specifically, the CPU 11c of the integrated control ECU 11 determines whether or not to perform drive control of the pump 13a of the EVP unit 13 based on the current consumption of the vehicle 1 output from the current sensor when the pressure in the constant pressure chamber of the brake booster 14 becomes higher than a predetermined threshold (normal drive threshold: EVP ON threshold in Figure 2) during idle stop control.

[0034] There is a correlation between the magnitude of the negative pressure in the constant pressure chamber of the brake booster 14 and the current consumed when the pump 13a of the EVP unit 13 is driven. When the pressure in the constant pressure chamber of the brake booster 14 reaches a predetermined threshold (normal drive threshold: EVP ON threshold in Figure 2), it is possible to experimentally estimate how much current will be consumed when the pump 13a of the EVP unit 13 is driven (estimated required current consumption). In this embodiment, the value of this estimated required current consumption is stored in the memory of the integrated control ECU 11.

[0035] The CPU 11c of the integrated control ECU 11 determines, when the pressure in the constant pressure chamber of the brake booster 14 rises above a predetermined threshold (normal drive threshold: EVP ON threshold in Figure 2), whether the sum of the value of the vehicle 1's current consumption output from the current sensor and the estimated required current consumption value exceeds the threshold for the vehicle 1's current consumption required to restart the engine 3 (idling stop release threshold). The CPU 11c of the integrated control ECU 11 acquires information regarding the vehicle 1's current consumption at a predetermined period (for example, 30ms).

[0036] If the CPU 11c of the integrated control ECU 11 determines that the sum of the current consumption of vehicle 1 and the estimated required current consumption exceeds the threshold for the current consumption of vehicle 1 required to restart engine 3 (idle stop release threshold), the CPU 11c of the integrated control ECU 11 will disable the operation of the pump 13a of the EVP unit 13, even though the pressure in the constant pressure chamber of the brake booster 14 is higher than the normal drive threshold. In other words, if the CPU 11c of the integrated control ECU 11 determines that the sum of the current consumption of vehicle 1 and the estimated required current consumption exceeds the idle stop release threshold, it will disable the operation of the pump 13a even if the negative pressure in the constant pressure chamber of the brake booster 14 is lower than the normal drive threshold. In this case, since the pump 13a is not driven, the current consumption of vehicle 1 will not exceed the idle stop release threshold.

[0037] If the CPU 11c of the integrated control ECU 11 determines that the sum of the current consumption of vehicle 1 and the estimated required current consumption does not exceed the threshold for the current consumption of vehicle 1 required to restart engine 3 (idling stop release threshold), it controls the drive of the pump 13a of the EVP unit 13. In this case, even if the negative pressure of the brake booster 14 decreases below the threshold (normal drive threshold) and the pump 13a of the EVP unit 13 is driven, the current consumption of vehicle 1 will not exceed the idling stop release threshold (release threshold based on the current consumption of vehicle 1).

[0038] When the sum of the current consumption of vehicle 1 output from the current sensor and the estimated required current consumption reaches the same value as the threshold for the current consumption of vehicle 1 required to restart engine 3 (idling stop release threshold), the CPU 11c of the integrated control ECU 11 can be arbitrarily set to either execute drive control or disable control of pump 13a.

[0039] Furthermore, when the CPU 11c of the integrated control ECU 11 controls the drive of the pump 13a, if the pressure in the constant pressure chamber of the brake booster 14 subsequently falls below a predetermined threshold (drive stop threshold), the CPU 11c of the EVP unit 13 stops driving the pump 13a. Here, falling below the drive stop threshold means approaching the vacuum pressure below that threshold. In this embodiment, the drive stop threshold is set to a value slightly higher (atmospheric pressure) than the pressure (limit negative pressure) that can be reached when the constant pressure chamber is evacuated by the pump 13a. Note that the drive stop threshold can be appropriately changed within the range between the normal drive threshold and the limit negative pressure.

[0040] Next, with reference to Figure 2, the idling stop control of this embodiment will be explained in comparison with the idling stop control of the conventional technology.

[0041] (When the engine automatically shuts off after stopping + the brake is pressed again while the engine is off: Conventional) As shown in Figure 2(a), in the conventional technology, during the process of automatic engine stop control, the vehicle decelerates first when the driver switches from the accelerator pedal to the brake pedal (brake pedal operation is ON) (time T1). As a result, the negative pressure in the constant pressure chamber of the brake booster decreases, but it does not decrease to the threshold required to drive the EVP unit's pump (corresponding to the normal drive threshold in this embodiment). Therefore, the drive control of the pump 13a is not performed at time T1.

[0042] The vehicle stops due to continued pressure on the brake pedal (time T2), and the engine stop condition is then met (time T3). At time T3, the engine is automatically shut down due to the meeting of the engine stop condition. At this time, the vehicle's current consumption decreases due to the engine shutdown. Also, because the brake pedal is still being pressed, the negative pressure in the constant pressure chamber of the brake booster at time T3 does not change significantly from time T1. Therefore, the negative pressure in the constant pressure chamber of the brake booster has not decreased to the threshold required to drive the EVP unit's pump (corresponding to the normal drive threshold in this embodiment), and the EVP unit's pump is not driven.

[0043] Suppose that at time T4, while the engine is under stop control (idling stop), the brake pedal is pressed again (first press). In this case, the negative pressure in the brake booster's constant pressure chamber decreases further. As a result, if at time T5 the negative pressure in the brake booster's constant pressure chamber falls below the threshold for driving the EVP unit's pump (corresponding to the normal drive threshold in this embodiment), the EVP unit's pump is driven to assist the negative pressure. When the pump is driven, the negative pressure in the brake booster's constant pressure chamber increases, so the negative pressure in the constant pressure chamber does not fall below the idling stop release threshold. Therefore, even if the brake pedal is pressed again during idling stop control, the idling stop control is not released based on the decrease in the negative pressure in the constant pressure chamber.

[0044] On the other hand, when the pump drive control is activated, the vehicle's current consumption increases. However, if the decrease in negative pressure in the constant pressure chamber is relatively small during the first re-pressure, and the vehicle's current consumption, which increased due to the pump drive control, does not exceed the idle stop release threshold (the release threshold due to current consumption), then the idle stop control is maintained.

[0045] If the brake pedal is pressed again frequently in a short period of time, the decrease in negative pressure in the brake booster's constant pressure chamber becomes significant. In this case, the drive load of the pump that compensates for the decrease in negative pressure increases, leading to an increase in current consumption. Therefore, if the brake pedal is pressed again for the second time at time T6, the vehicle's current consumption will increase further. As a result, if the vehicle's current consumption exceeds the idle stop release threshold at time T7, the idle stop control will be released at time T7 and the engine will be restarted. When the engine is restarted, the vehicle's current consumption will increase further due to the startup of the ECU and other processes.

[0046] The EVP unit's pump is stopped when the negative pressure in the brake booster's constant pressure chamber recovers to a predetermined threshold (time T8), which in turn reduces the vehicle's current consumption.

[0047] As described above, with conventional technology, even if the engine is stopped by idle stop after the vehicle has come to a complete stop, if the brake is pressed again afterward, the idle stop state may be canceled due to the increase in vehicle current consumption associated with driving the EVP unit's pump. This can happen not only when the brake pedal is pressed again, but also when the brake pedal is pressed further while the idle stop state is active, or when there is a change in the amount of brake pedal depression that the driver is not aware of, as the decrease in negative pressure in the constant pressure chamber can drive the pump and cancel the idle stop state.

[0048] (When the engine automatically shuts off after stopping + the brake is pressed again while the engine is off: This invention) As shown in Figure 2(b), in this embodiment, during the process of automatic stop control of the engine 3, the vehicle 1 decelerates first when the driver switches from the accelerator pedal to the brake pedal 19 (operation of the brake pedal 19 is ON) (time T11). As a result, the negative pressure in the constant pressure chamber of the brake booster 14 decreases, but it does not decrease to the normal drive threshold required for the normal drive of the pump 13a of the EVP unit 13. Therefore, at time T11, the drive control of the pump 13a of the EVP unit 13 is not performed.

[0049] If the brake pedal 19 is continuously pressed, vehicle 1 will stop at time T12, and if the conditions for stopping engine 3 are met at time T13, automatic engine stop control (idle stop control) will be performed for engine 3. Consequently, the current consumption of vehicle 1 will decrease. Next, let's assume that at time T14, while the engine is being stopped (idle stop), the brake pedal 19 is pressed again. Consequently, the negative pressure in the constant pressure chamber of the brake booster 14 will decrease, and let's assume that at time T15 it will decrease to the normal drive threshold at which the drive control of the pump 13a of the EVP unit 13 is performed.

[0050] At this time, the CPU 11c of the integrated control ECU 11 determines whether the sum of the current consumption of the vehicle 1 at that time and the estimated required current consumption stored in memory beforehand exceeds the threshold for the current consumption of the vehicle 1 required to restart the engine 3 (idling stop release threshold). If the CPU 11c of the integrated control ECU 11 determines that the sum does not exceed the idling stop release threshold (release threshold based on current consumption), it controls the drive of the pump 13a of the EVP unit 13 (see vehicle current consumption (i) in Figure 2(b)).

[0051] As a result, the negative pressure in the constant pressure chamber of the brake booster 14 increases, preventing the negative pressure from falling below the idle stop release threshold (release threshold based on negative pressure), and thus avoiding the release of idle stop control due to a decrease in the negative pressure in the constant pressure chamber.

[0052] Furthermore, although the driving of pump 13a increases the current consumption of vehicle 1, it does not exceed the idle stop release threshold (release threshold based on current consumption), thus preventing the idle stop control from being released due to the increased current consumption of vehicle 1.

[0053] The drive control of the pump 13a of the EVP unit 13 is stopped when the negative pressure in the constant pressure chamber of the brake booster 14 recovers to a predetermined threshold (time T16), and consequently the vehicle's current consumption decreases.

[0054] Therefore, according to this embodiment, when the engine 3 is in an automatically stopped state (idling stop state) and the negative pressure in the constant pressure chamber of the brake booster 14 decreases to the normal drive threshold, the CPU 11c of the integrated control ECU 11 controls the driving of the pump 13a of the EVP unit 13 if it determines that the current consumption of the vehicle 1 will not exceed the idling stop release threshold (release threshold based on current consumption) even if the pump 13a is driven. In this way, when the pump 13a, which is used to assist the negative pressure in the constant pressure chamber of the brake booster 14, is driven during idling stop control, the current consumption of the vehicle 1 will not exceed the idling stop release threshold, thus preventing the idling stop control from being released based on an increase in the current consumption of the vehicle 1. This improves the continuity of idling stop control and improves the fuel efficiency of the vehicle 1.

[0055] Furthermore, if the current consumption of vehicle 1 does not exceed the idle stop release threshold (release threshold based on current consumption) even when the pump 13a of the EVP unit 13 is driven, the drive control of the pump 13a is performed. In this case, it is possible to prevent the idle stop control from being released due to the negative pressure in the constant pressure chamber of the brake booster 14 falling below the idle stop release threshold (release threshold based on the decrease in negative pressure). This improves the continuity of the idle stop control, thereby improving the fuel efficiency of vehicle 1.

[0056] (modified version) Next, a modified example of the above-described embodiment will be explained, mainly with reference to Figure 2(b) (in particular, vehicle current consumption (ii) in Figure 2(b)). The difference between this example and the above-described embodiment is that the method for preventing the current consumption of vehicle 1 from exceeding the idle stop release threshold is different. The following explanation will focus on these differences.

[0057] During idle stop control, if the pressure in the constant pressure chamber of the brake booster 14 becomes higher than a predetermined threshold (normal drive threshold: EVP ON threshold in Figure 2) (i.e., the negative pressure in the constant pressure chamber decreases to the normal drive threshold), the CPU 11c of the integrated control ECU 11 controls the drive of the pump 13a within a range where the current consumption of the vehicle 1 does not exceed the idle stop release threshold.

[0058] For example, the CPU 11c of the integrated control ECU 11 acquires the value of the vehicle's current consumption when the pressure in the constant pressure chamber of the brake booster 14 exceeds a predetermined threshold (normal drive threshold: EVP ON threshold in Figure 2), and calculates the difference between this value and the idle stop release threshold (release threshold based on current consumption). Then, the CPU 11c of the integrated control ECU 11 controls the drive of the pump 13a so that the current consumption when the pump 13a is driven falls within the range of the calculated difference. Specifically, when the pump 13a is driven by a motor, the current consumption when the pump 13a is driven is adjusted by switching the voltage applied to the motor ON / OFF at a predetermined frequency.

[0059] For example, suppose a motor is used that consumes 1A of current when the duty cycle of the voltage ON / OFF pulse is 100%, and the difference between the current consumption of vehicle 1 when the negative pressure in the constant pressure chamber reaches the normal drive threshold and the idle stop release threshold (release threshold based on current consumption) is 0.5A. In this case, the CPU 11c of the integrated control ECU 11 controls the drive of pump 13a so that the voltage applied to the motor of pump 13a is less than the duty cycle = 50%.

[0060] The motor used to drive the pump 13a can be either a brushless motor or a brushed motor, but it is preferable to use a brushless motor because it is easier to adjust the duty cycle of the applied voltage.

[0061] Next, the idle stop control of this embodiment will be described with reference to Figure 2(b) (particularly vehicle current consumption (ii) in Figure 2(b)).

[0062] (Example: When the engine automatically shuts off after coming to a stop + the brake is pressed again while the engine is off) As shown in Figure 2(b), in this embodiment, during the process of automatic stop control of the engine 3, the vehicle 1 decelerates first when the driver switches from the accelerator pedal to the brake pedal 19 (operation of the brake pedal 19 is ON) (time T11). As a result, the negative pressure in the constant pressure chamber of the brake booster 14 decreases, but it does not decrease to the normal drive threshold required for the normal drive of the pump 13a of the EVP unit 13. Therefore, at time T11, the drive control of the pump 13a of the EVP unit 13 is not performed.

[0063] If the brake pedal 19 is continuously pressed, vehicle 1 will stop at time T12, and if the conditions for stopping engine 3 are met at time T13, automatic engine stop control (idle stop control) will be performed for engine 3. Consequently, the current consumption of vehicle 1 will decrease. Next, let's assume that at time T14, while the engine is being stopped (idle stop), the brake pedal 19 is pressed again. Consequently, the negative pressure in the constant pressure chamber of the brake booster 14 will decrease, and let's assume that at time T15 it will decrease to the normal drive threshold at which the drive control of the pump 13a of the EVP unit 13 is performed.

[0064] At this time, the CPU 11c of the integrated control ECU 11 calculates the difference current value from the current consumption value to the idle stop release threshold (release threshold based on the current consumption value of the vehicle 1) based on the current consumption of the vehicle 1 when the negative pressure in the constant pressure chamber of the brake booster 14 decreases to the normal drive threshold. Then, the CPU 11c of the integrated control ECU 11 controls the drive of the pump 13a while adjusting the ON / OFF duty cycle of the voltage applied to the motor so that the current consumption required to drive the pump 13a falls within the range of the calculated difference current value.

[0065] In this manner, the operation of the pump 13a increases the negative pressure in the constant pressure chamber of the brake booster 14, preventing the negative pressure from falling below the idle stop release threshold (release threshold based on negative pressure), and thus avoiding the release of idle stop control due to a decrease in the negative pressure in the constant pressure chamber.

[0066] Furthermore, although the driving of pump 13a increases the current consumption of vehicle 1, it does not exceed the idle stop release threshold (release threshold based on current consumption), thus preventing the idle stop control from being released due to the increased current consumption of vehicle 1.

[0067] The drive control of the pump 13a of the EVP unit 13 is stopped when the negative pressure in the constant pressure chamber of the brake booster 14 recovers to a predetermined threshold (time T16), and consequently the vehicle's current consumption decreases.

[0068] As described above, controlling the current consumption of vehicle 1 using the method described in this example yields the same effects as the embodiments described above.

[0069] It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention. For example, in the embodiments described above, various processes are performed by a single ECU (integrated control ECU 11), but for example, the EFI control unit, idle stop control unit, CVT control unit, ABS / VSC control unit, and EVP control unit may be configured as separate ECUs. In this case, for example, each ECU may exchange necessary information with each other via a communication bus such as CAN.

[0070] Furthermore, the above-described embodiments can be applied not only to gasoline-powered vehicles, but also to electric vehicles, hybrid vehicles, and autonomous vehicles.

[0071] Furthermore, the present invention can be applied to a vehicle equipped with a control means that stops an operating engine when a predetermined automatic engine stop condition is met, and automatically restarts a stopped engine when a predetermined engine restart condition is met. [Explanation of symbols]

[0072] 1. Idling stop vehicle 11. Integrated Control ECU (Negative Pressure Assistance Means) 14. Brake booster (brake assist device) 13. EVP unit (negative pressure assisting means) 13a Pump

Claims

1. In a vehicle control device that stops an engine in operation when predetermined automatic engine stop conditions are met, and automatically restarts a stopped engine when predetermined engine restart conditions are met, A brake assist mechanism that uses engine vacuum to assist the brakes, A negative pressure assisting means that supplies auxiliary negative pressure to the brake assisting means by controlling the drive of the pump, Equipped with, The predetermined engine restart condition includes the vehicle's current consumption, including the current required to drive the pump, exceeding a threshold value related to the engine restart condition. When the negative pressure assisting means supplies auxiliary negative pressure to the brake assisting means while the engine is automatically stopped, it controls the pump to be disabled if the threshold for the engine restart condition is exceeded, and drives the pump if the threshold for the engine restart condition is not exceeded. A vehicle control device characterized by the following features.

2. The vehicle control device according to claim 1, characterized in that the pump is an electrically driven negative pressure pump.

3. The vehicle control device according to claim 1 or 2, characterized in that the negative pressure assisting means drives the pump when it is determined that the current consumption of the vehicle does not exceed the threshold for the engine restart condition even when the pump is driven.

4. The vehicle control device according to claim 2, characterized in that when the negative pressure assisting means supplies auxiliary negative pressure to the brake assisting means while the engine is automatically stopped, it adjusts the on and off cycle of the voltage applied to the pump so that the current consumption of the vehicle when the pump is driven does not exceed the threshold for the engine restart condition.

Images