JP2017133400A - Vehicle stop maintaining device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle stop maintaining device capable of executing both a vehicle stop state maintaining function and a fuel efficiency improvement function.SOLUTION: A vehicle stop maintaining device comprises: an idling stop device 2; a DSC device 4; an ECU 6 which activates the idling stop device 2 to stop an engine 7 when brake fluid pressure Pb in accordance with pressing operation of a brake pedal 10 exceeds a threshold t1 and executes automatic hold control by activating the DSC device 4 when the brake fluid pressure Pb exceeds the threshold t3; and an automatic hold switch 60 which can switch between a permission mode to permit the automatic hold control through the DSC device 4 and a prohibition mode to prohibit the same. The ECU 6 is adapted to change the threshold t1 to the threshold t2 lower than the same when the permission mode to permit the automatic hold control through the DSC device 4 is selected.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vehicle stop maintaining device, and more particularly to a vehicle stop maintaining device capable of maintaining a stop state by operating a braking force control device when a vehicle stop state is detected.

Conventionally, as a braking device for a vehicle, a foot brake device capable of braking a wheel by supplying a brake hydraulic pressure corresponding to a depression operation of a brake pedal to a hydraulic brake mechanism, and a brake hydraulic pressure supplied to the hydraulic brake mechanism A braking force control device capable of braking the wheel by controlling the pressurizing means independently of the depression operation of the brake pedal, and driven by an electric actuator independent of the depression operation of the brake pedal. There is known an electric parking brake device that can actuate an electric brake mechanism to brake a wheel.
Further, when a stop state of the vehicle is detected, a brake force control device represented by an anti-lock brake system (ABS) or a dynamic stability control system (DSC) is operated, so that an occupant can depress the brake pedal. Techniques for reducing the accompanying load have been proposed.

On the other hand, vehicles equipped with an automatic engine stop / restart mechanism, that is, a so-called idle stop mechanism, are known for the purpose of improving fuel consumption and emissions.
In a vehicle equipped with such an automatic stop / restart mechanism, when a stop state of the vehicle such as waiting for a signal is detected during traveling, the fuel supply to the engine is stopped to stop the engine, and the accelerator pedal is depressed. When is detected, the fuel supply to the engine is started and the engine is restarted.

  The vehicle control device disclosed in Patent Document 1 includes a brake hold unit, an engine start unit that makes an engine start request when one of a plurality of start conditions is satisfied, and a predetermined first start among a plurality of start conditions. Brake hold standby is provided with a driving support means for forcibly starting the engine when the condition is satisfied and a brake hold standby button capable of selectively switching between operation and non-operation of the brake hold means. When the button is turned on, the driving support means is not executed when a predetermined second start condition among the first start conditions is satisfied and an engine start request is not made by the engine start means. . As a result, coordinated control of idle stop and auto hold is performed in accordance with the passenger's request.

JP-A-2015-113803

In general, the idle stop control sets threshold values for the vehicle speed corresponding to the stop state of the vehicle, the accelerator opening corresponding to the occupant's intention to start, the brake fluid pressure corresponding to the occupant's intention to stop, and these threshold values and the vehicle. Whether or not execution is possible is determined based on the comparison with the operation state.
In particular, during the idle stop, when the brake pedal depressing force variation and the torque variation that occurs when the engine is restarted occur, there is a concern that the vehicle may not be predicted depending on the brake fluid pressure that is held. For this reason, the idle stop execution threshold value of the brake fluid pressure is set to a high value, and the braking force necessary to maintain the vehicle stop state is ensured.
Therefore, from the viewpoint of safety, the idle stop control can be executed only in the operation region limited to the entire operation region, and a sufficient fuel efficiency improvement effect cannot be expected.

In the vehicle control device of Patent Document 1, since the driving support means for forcibly starting the engine is not executed, the idle stop control according to the passenger's request is executed in a vehicle capable of executing the idle stop control and the auto hold control. can do.
However, since no consideration has been made regarding the idling stop execution threshold value of the brake fluid pressure, it is impossible to expand the operating range in which the idling stop control can be executed, and there is room for improvement in terms of fuel efficiency improvement effect. ing.

  An object of the present invention is to provide a vehicle stop maintenance device that can improve fuel efficiency while ensuring a stop state maintenance function by cooperatively controlling idle stop and auto hold.

  According to another aspect of the present invention, there is provided an automatic stop / restart mechanism capable of automatically stopping / restarting an engine in accordance with a driving state of the vehicle in a state where the driving torque of the engine can be transmitted to driving wheels, and a brake fluid. A brake force control mechanism capable of braking the wheel by controlling the pressure and holding the brake fluid pressure according to the operation of the brake pedal, and when the brake fluid pressure according to the depression operation of the brake pedal exceeds a first threshold value In a vehicle stop maintaining device that includes a control means for operating the automatic stop / restart mechanism to stop the engine, a permission mode for permitting the operation of the braking force control mechanism and a prohibit mode for not permitting can be switched. Switching means, and the control means sets a second threshold value lower than the first threshold value instead of the first threshold value when the braking force control mechanism is in the permission mode. .

  In this vehicle stop keeping device, the control means sets a second threshold value lower than the first threshold value instead of the first threshold value when the braking force control mechanism is in the permission mode. The brake fluid pressure can be maintained independently, and the operating range of the automatic stop / restart mechanism can be expanded while ensuring the vehicle stop state maintaining function, and the fuel efficiency improvement effect can be enhanced.

According to a second aspect of the present invention, in the first aspect of the invention, there is provided a gear-in state detecting means for detecting a gear-in state in which the driving torque of the engine can be transmitted to the drive wheels, and an accelerator pedal operation detecting means for detecting a depression operation of the accelerator pedal And the control means restarts the engine via the automatic stop / restart mechanism when the accelerator pedal is depressed in a gear-in state.
According to this configuration, it is possible to improve the starting characteristics of the vehicle from when the engine is restarted.

According to a third aspect of the present invention, in the second aspect of the invention, there is provided a driving force state determining means capable of determining a stable state of the driving force of the engine. The brake fluid pressure is released through the braking force control mechanism when an operation is detected.
According to this configuration, it is possible to prevent the vehicle from unexpectedly popping out.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the brake force control mechanism is configured such that a brake fluid pressure corresponding to a depression operation of a brake pedal is set lower than the second threshold value. The brake fluid pressure is maintained when the third threshold value is exceeded.
According to this configuration, it is possible to obtain a vehicle start characteristic suitable for the occupant's intention to start.

  According to the vehicle stop maintenance device of the present invention, it is possible to achieve both the vehicle stop state maintenance function and the fuel efficiency improvement function.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. It is a block diagram of a stop maintenance device. It is a schematic diagram which shows a part of foot brake device, DSC device, and EPB device. It is a map which shows an idle stop execution threshold value and an auto hold execution threshold value. It is a flowchart of a stop maintenance control process. It is a flowchart of a control release process.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The following description exemplifies the application of the present invention to a vehicle stop and maintenance device, and does not limit the present invention, its application, or its use.

Embodiment 1 of the present invention will be described below with reference to FIGS.
The vehicle V of the present invention is equipped with a stop maintenance device 1.
As shown in FIGS. 1 and 2, the stop maintaining device 1 includes an idle stop device 2 (automatic stop / restart mechanism), a foot brake device 3, and a DSC (Dynamic Stability Control System) device 4 (braking force control mechanism). And an EPB (Electric Parking Brake) device 5, an ECU (Electronic Control Unit) 6 (control means), and the like.

First, the idle stop device 2 will be described.
The idle stop device 2 is configured to be able to automatically stop and restart the engine 7 in accordance with the driving state of the vehicle V in a state where the driving torque of the engine 7 can be transmitted to the driving wheels.
As shown in FIG. 2, the idle stop device 2 includes an Eng control unit 6a, an engine 7, and the like.

The engine 7 transmits driving force to the automatic transmission 8 by fastening a clutch (not shown) via a torque converter (not shown).
The engine 7 stops fuel injection when receiving an engine stop execution command from the Eng control unit 6a, and executes a restart operation when receiving an engine restart execution command.
The automatic transmission 8 receives an input signal from each sensor, converts the driving force input from the engine 7 into a predetermined torque and rotation speed according to the running state and the shift range selected by the occupant, It is transmitted to the drive wheels via a differential device (both not shown).

When the engine control unit 6a receives an input signal from each sensor and determines that the engine stop condition is satisfied, the engine control unit 6a automatically stops the engine 7 (idle stop), and the engine restart condition is satisfied after the engine 7 is automatically stopped. When it is determined that it has been established, an execution signal for restarting the engine 7 can be output.
The Eng control unit 6a receives an input signal from the engine rotation speed sensor 57, and when the engine is restarted, the cranking state rotated by a cell motor (not shown) and the driving force of the engine 7 are hunting. The driving force stable state in which the driving force is stable through the stable state can be determined.

Here, the cranking state is a state where the rotational speed of the engine 7 is equal to or lower than the rotational speed of the cell motor, the unstable driving force state is a state where the difference between the upper limit value and the lower limit value of the driving force is a predetermined threshold value or more, The stable state is a state in which the difference between the upper limit value and the lower limit value of the driving force is less than a predetermined threshold value.
The Eng control unit 6a calculates the time determined by the respective moving averages from the engine restart executed in the past to the cranking completion state and the driving force stable state for the cranking completion state determination time and the driving force stable state determination time. Are held in advance, and when the engine 7 is restarted, the cranking completion state and the driving force stable state are respectively determined by the elapsed time from the engine restart.

  As shown in FIG. 1, the shift device 9 is installed inside the device, a shift lever 9 a that can be operated by a passenger, a shift indicator corresponding to each of the D, N, R, and P ranges set in order from the bottom. A shift position sensor 61 (see FIG. 2) (gear-in state detecting means) is provided. The shift position sensor 61 is an occupant based on a relative position between a movable sensor provided on a slider that slides according to the movement of the shift lever 9a and a fixed sensor provided on a support portion (not shown) that supports the slider. Detects a shift position corresponding to the selected shift range. When the shift lever 9a is operated in the D and R ranges, the gear 7 is in a gear-in state in which the driving force (driving torque) of the engine 7 can be transmitted to the driving wheels.

Next, the foot brake device 3 will be described.
The foot brake device 3 supplies brake fluid (hereinafter referred to as brake fluid pressure Pb) pressurized according to the depression operation of the brake pedal 10 to the two pairs of front and rear hydraulic brake mechanisms 20 to provide two pairs of front and rear wheels 11. Is configured to be brakeable.
As shown in FIGS. 1 and 3, the foot brake device 3 includes a brake pedal 10, a master cylinder 12, a booster 13, a hydraulic brake mechanism 20, and the like.
The booster 13 has a movable wall (not shown) that can move in the axial direction in conjunction with the brake pedal 10, and the brake pedal uses the differential pressure between the negative pressure chamber and the atmospheric chamber partitioned by the movable wall. 10 stepping force is boosted. The hydraulic brake mechanism 20 provided on each of the wheels 11 is connected to the master cylinder 12 by a pipe line 27, and applies a braking force to each wheel 11 according to the depression operation of the brake pedal 10 by the occupant.

  As shown in FIG. 3, each hydraulic brake mechanism 20 includes a rotor disk 21 provided on the wheel 11 so as to be integrally rotatable, a caliper 22 that can apply a braking force to the rotor disk 21, and the like. The caliper 22 includes a caliper main body 23 disposed in a bowl shape on the rotor disk 21, and outer brake pads 24 disposed on both sides of the rotor disk 21 inside the caliper main body 23, and an inner brake pad 24. Side brake pad 25.

A piston 26 that is movable in the axial direction of the rotor disk 21 is disposed inside the inner brake pad 25. The piston 26 is slidably inserted into a cylinder hole 23a formed in the caliper body 23. Has been. A pipe line 27 is connected to the cylinder hole 23a.
When the occupant depresses the brake pedal 10, the brake fluid pressure flows through the pipe line 27 and is supplied to the cylinder hole 23 a, and the piston 26 is moved forward in the axial direction.
Along with this, the inner brake pad 25 is pressed against the inner side of the rotor disk 21, and this reaction force moves the caliper body 23 toward the inner side, and the outer brake pad 24 is pressed against the outer side of the rotor disk 21. As described above, the braking force of the foot brake device 3 is generated.

Next, the DSC apparatus 4 will be described.
The DSC device 4 is configured to be able to brake the wheel 11 independently of the depression operation of the brake pedal 10, and in addition to the attitude control function such as DSC control and ABS control, the auto hold control that maintains the stop state of the vehicle V Is configured to run.
Further, the DSC device 4 starts the auto hold control when it is determined that the auto hold execution condition is satisfied, and continuously maintains the stop state of the vehicle V until the auto hold cancel condition is satisfied. Is formed.
As shown in FIG. 2, the DSC apparatus 4 includes a DSC control unit 6b, a pressurizing unit 30 (pressurizing means), and the like.

The DSC control unit 6b receives input signals from each sensor and executes DSC control in order to improve traveling stability when the vehicle V is turning. Specifically, when it is determined that the turning posture of the vehicle V has collapsed to a predetermined value or more based on detection signals from the yaw rate sensor 53, the lateral acceleration sensor 55, and the wheel speed sensor 56, the DSC control unit 6b adds The braking force of each wheel 11 is controlled by the operation of the pressure unit 30, and the yaw moment is applied to the vehicle body to converge the turning posture of the vehicle V in the target direction.
Further, the DSC control unit 6b receives an input signal from each sensor and executes ABS control to prevent the wheels 11 from being locked. Specifically, the DSC control unit 6b calculates the slip ratio of each wheel 11 based on the detection signal of the wheel speed sensor 56, and when the calculated slip ratio detects a wheel 11 that exceeds a predetermined threshold, The operation of the pressure unit 30 is controlled to reduce the braking force acting on the corresponding wheel 11 to prevent wheel lock.

As shown in FIG. 3, the pressurizing unit 30 includes a hydraulic pump 31, a pressurizing valve 32, a return valve 33, a brake hydraulic pressure sensor 34 that can detect the brake hydraulic pressure in the conduit 27, and the like. I have.
The hydraulic pump 31 is arranged in a first branch path 27a branched from the pipe 27, and is constituted by an electric pump using an electric motor as a drive source. The hydraulic pump 31 is supplied with electric power from an alternator during engine operation, and is supplied with electric power from an in-vehicle battery (not shown) while the engine is stopped, and is controlled by the DSC control unit 6b.
The pressurizing valve 32 is disposed in the first branch path 27 a between the hydraulic pump 31 and the pipe line 27, and the return valve 33 is disposed in the second branch path 27 b branched from the pipe line 27. The valves 32 and 33 are constituted by electromagnetic open / close valves, and are controlled by the DSC control unit 6b.

Next, the EPB apparatus 5 will be described.
The EPB device 5 is driven independently of the depression operation of the brake pedal 10 and is configured to execute auto parking control for maintaining the stopped state of the vehicle V when a predetermined condition is satisfied.
As shown in FIG. 2, the EPB device 5 includes an EPB controller 6c, an electric brake mechanism 40, and the like.

As shown in FIG. 3, the electric brake mechanism 40 includes a piston 41, an annular member 42, an electric motor 43, and the like.
A male screw portion 41 a is formed on the inner end side portion of the piston 41, and the male screw portion 41 a and a female screw portion 42 a formed on the inner surface portion of the annular member 42 are screwed together. A gear surface portion 42 b is formed on the outer surface portion of the annular member 42, and is screwed with a pinion 44 attached to a drive shaft of the electric motor 43 so as to be integrally rotatable. Thereby, by driving the electric motor 43, the annular member 42 is rotationally driven, and the piston 41 is moved forward and backward with respect to the axial direction.

Next, the ECU 6 will be described.
The ECU 6 includes a CPU (Central Processing Unit), a ROM, a RAM, an in-side interface, an out-side interface, and the like.
Various programs and data for controlling the braking force are stored in the ROM, and a processing area used when the CPU performs a series of processes is provided in the RAM.
The ECU 6 is configured to be capable of automatic stop / restart, auto hold and auto parking of the engine 7, and when the brake hydraulic pressure Pb corresponding to the depression operation of the brake pedal 10 exceeds the idle stop execution threshold t1, the idle stop device 2 is set. It is configured to set a threshold value t2 lower than the threshold value t1 in place of the threshold value t1 in the permission mode in which the engine 7 is stopped by operating and the auto hold switch 60 is turned on.

  As shown in FIG. 2, the ECU 6 includes a brake lamp switch 51, an accelerator sensor 52 (accelerator pedal operation detecting means), a yaw rate sensor 53, a rudder angle sensor 54, a lateral acceleration sensor 55, a wheel speed sensor 56, The engine speed sensor 57, the gradient sensor 58, the parking switch 59, the auto hold switch 60, the shift position sensor 61, the ignition switch 62, the brake fluid pressure sensor 34, and the like are electrically connected.

The brake lamp switch 51 detects a depression operation of the brake pedal 10 by an occupant and outputs a detection signal, and the accelerator sensor 52 detects a depression amount of the accelerator pedal 14 and outputs a detection signal. The yaw rate sensor 53 outputs a signal corresponding to the yaw rate of the vehicle V, and the steering angle sensor 54 outputs a signal related to the steering angle of a steering wheel (not shown) by the occupant. The lateral acceleration sensor 55 outputs a signal related to the vehicle width direction of the vehicle V, and the wheel speed sensor 56 outputs a signal corresponding to the rotational speed of the wheel 11.
The engine rotation speed sensor 57 outputs a signal corresponding to the rotation speed (rotation speed) of the engine, and the gradient sensor 58 outputs a signal corresponding to the inclination angle of the road surface on which the vehicle V is stopped. The sensor 34 outputs a signal corresponding to the brake fluid pressure in the pipe line 27.
The shift position sensor 61 detects a shift range selected by the occupant and outputs a detection signal, and the ignition switch 62 detects an on / off state of the ignition switch and outputs a detection signal.

The parking switch 59 is configured by a momentary changeover switch that outputs an H (logic high) level signal only when switching is performed by an occupant, and otherwise outputs an L (logic low) level signal. When the EPB device 5 is operated by being turned on, the auto parking control is executed until the operation is switched to the off state.
The auto hold switch 60 is constituted by a momentary type changeover switch that outputs an H level signal only when the occupant switches, and otherwise outputs an L level signal. When the occupant switches the auto hold switch 60 to the on state in the prohibit mode operated to the off state, a permission mode for permitting execution of the auto hold control is set and the permission mode is operated to the on state. When the occupant switches the auto hold switch 60 to the off state, a prohibit mode for prohibiting execution of the auto hold control is set.

As shown in FIG. 2, the ECU 6 is integrally provided with an Eng control unit 6a, a DSC control unit 6b, an EPB control unit 6c, and the like.
The Eng control unit 6a changes the engine stop condition and the engine restart condition between the permission mode in which the auto hold switch 60 is in the on state and the prohibit mode in the off state, based on the map M stored in the ECU 6 in advance. It is configured.

Here, the map M will be described.
As shown in FIG. 4, the map M defines a depression force F of the brake pedal 10 and a brake fluid pressure Pb corresponding to the depression force F, and idle stop execution threshold values t1 (first threshold value) and t2 (second threshold value). ) And auto-hold execution threshold t3 (third threshold) are set (t3 <t2 <t1).
The threshold t3 corresponds to the pedaling force F3 reflecting the intention of stopping the vehicle V by the occupant, the threshold t2 corresponds to the pedaling force F2 reflecting the stopping intention stronger than the intention of stopping the pedaling force F3, and the threshold t1 is based on the pedaling force F2. Is set to correspond to a large pedaling force F1. These pedaling forces F1 to F3 are pedaling force values that can be consciously stepped on by the passenger.

When in the prohibit mode in which the auto hold switch 60 is in the off state, the engine stop condition is that the brake fluid pressure Pb exceeds the threshold value t1 corresponding to the stepping force F1, and the engine restart condition is a return operation of the brake pedal 10. .
When in the permission mode in which the auto hold switch 60 is in the on state, the engine stop condition is that the brake fluid pressure Pb exceeds a threshold value t2 corresponding to the stepping force F2, and the engine restart condition is that the accelerator pedal 14 is depressed in the gear-in state. It is.
In this embodiment, only the brake fluid pressure Pb is set as the engine stop condition. However, in addition to the brake fluid pressure Pb, determination conditions such as the vehicle speed, the accelerator opening, the battery voltage, and the shift range are selectively added, When the condition is satisfied, the engine may be stopped.

In the permission mode, the DSC control unit 6b performs auto hold control on condition that the brake fluid pressure Pb exceeds a threshold value t3 corresponding to the pedaling force F3, and executes the depression operation of the accelerator pedal 14 in a stable driving force state. The auto hold control is canceled on the condition.
Then, the DSC control unit 6b controls the pressurizing unit 30 so as to continuously hold the brake fluid pressure Pb corresponding to the depression force F of the brake pedal 10 by the occupant when the auto hold is executed, and holds when the auto hold is released. The pressurizing unit 30 is controlled so as to release the brake fluid pressure Pb being applied at a predetermined release speed.

The EPB control unit 6c executes auto parking control on the condition that the ignition switch is turned off in the P range when auto hold is executed.
The EPB control unit 6c controls the wheel braking force of the electric brake mechanism 40 to be a predetermined load based on an ON signal of the parking switch 59 or an execution signal of auto parking control.

Next, the stop maintenance control processing procedure will be described based on the flowcharts of FIGS. 5 and 6, Si (i = 1, 2,...) Indicates a step for each process.
As shown in the flowchart of FIG. 5, in the stop maintenance control process, first, in S1, information such as detection values of each sensor and threshold values t1 to t3 is read, and the process proceeds to S2.
In S2, it is determined whether or not all the flags f1 to f3 are the initial value 0.
The flag f1 is set to 1 when the idle stop control and the auto hold control are executed, the flag f2 is set to 1 when the auto hold control is executed only, and the flag f3 is set to 1 when the idle stop control is executed only. Is set.

If the flags f1 to f3 are all 0 as a result of the determination in S2, since neither the idle stop control nor the auto hold control is executed, the process proceeds to S3 to determine whether or not the vehicle V is in a stopped state. To do. As a result of the determination in S2, if any of the flags f1 to f3 is 1, at least one of the idle stop control and the auto hold control is being executed, the process proceeds to S13, and the control release process is executed. Return.
As a result of the determination in S3, when the vehicle V is in a stopped state, the process proceeds to S4 to determine whether or not the brake fluid pressure Pb exceeds the threshold value t3. Thereby, the stop intention of the vehicle V by the passenger is determined. If the result of determination in S3 is that the vehicle V is not in a stopped state, the process returns.

As a result of the determination in S4, when the brake fluid pressure Pb exceeds the threshold value t3, the process proceeds to S5, and it is determined whether or not the auto hold switch 60 is turned on by the occupant.
If the result of determination in S4 is that the brake fluid pressure Pb is less than or equal to the threshold value t3, the process returns.
As a result of the determination in S5, when the auto hold switch 60 is turned on by the occupant, the auto hold execution condition is satisfied, so the routine proceeds to S6 and the auto hold control is executed.

In S7, it is determined whether or not the brake fluid pressure Pb exceeds the threshold value t2.
As a result of the determination in S7, when the brake fluid pressure Pb exceeds the threshold value t2, the process proceeds to S8, and after setting the flag f1 to 1, the engine 7 is stopped (S9) and the process returns.
If the brake fluid pressure Pb is equal to or less than the threshold value t2 as a result of the determination in S7, it is not a pedaling force reflecting a strong intention to stop by the occupant, so after setting the flag f2 to 1 (S10), the engine 7 is not stopped. Return. Thereby, for example, a high start characteristic can be obtained when turning right.

If the result of the determination in S5 is that the auto hold switch 60 has not been turned on by the occupant, the routine proceeds to S11 where it is determined whether or not the brake fluid pressure Pb exceeds the threshold value t1.
As a result of the determination in S11, when the brake fluid pressure Pb exceeds the threshold value t1, the auto-hold control is not executed. Therefore, after setting the flag f3 to 1 (S12), the process proceeds to S9 and the engine 7 is stopped. To do. Thereby, even if it is an idle stop of prohibition mode, the unexpected jumping out of the vehicle V can be avoided and high safety | security can be ensured.

The control release process will be described based on the flowchart of FIG.
First, in S21, it is determined whether or not the brake pedal 10 has been depressed.
If the result of determination in S21 is that the brake pedal 10 has been depressed, the process proceeds to S22, where it is determined whether or not the flag f3 is set to 1.
If the result of determination in S21 is that the brake pedal 10 has not been depressed, the process ends.

As a result of the determination in S22, when the flag f3 is set to 1, since the restart condition of the engine 7 in the idle stop in the prohibit mode is satisfied, the process proceeds to S23 and the engine 7 is restarted.
Next, the process proceeds to S24, the flag f3 is set to 0, and the process ends.

If the flag f3 is not set to 1 as a result of the determination in S22, the process proceeds to S25 to determine whether or not the accelerator pedal 14 has been depressed.
As a result of the determination in S25, when the accelerator pedal 14 is depressed, the process proceeds to S26 to determine whether or not the flag f2 is set to 1.
If the flag f2 is set to 1 as a result of the determination in S26, only the auto-hold is being executed and the auto-hold release condition is satisfied, so the flag f2 is set to 0 (S27) and the auto-hold is set. After canceling (S28), the process ends.

As a result of the determination in S26, when the flag f2 is not set to 1, since the idle stop in the permission mode is being executed, the process proceeds to S29, and whether or not the D range or the R range is selected (gear-in state). judge.
If the D range or the R range is selected as a result of the determination in S29, the restart condition of the engine 7 in the idling stop in the permission mode is satisfied, so that the process proceeds to S30 and whether or not the engine 7 is stopped. judge.
As a result of the determination in S30, when the engine 7 is stopped, the process proceeds to S31 and the engine 7 is restarted.

Next, in S32, it is determined whether or not the driving force is stable.
If the result of determination in S32 is that the driving force is in a stable state, the auto-hold release condition is satisfied, so the flag f1 is set to 0 (S33), and the flow proceeds to S28.
If the result of the determination in S30 is that the engine 7 is not stopped, the engine 7 has already been restarted and waiting for the driving force to stabilize, so the routine proceeds to S32.
If the accelerator pedal 14 is not depressed as a result of the determination in S25, if the D range or the R range is not selected as a result of the determination in S29, if the driving force is not stable as a result of the determination in S32, the process ends. To do.

Next, the operation and effect of the stop maintenance device 1 will be described.
According to the present stop maintenance device 1, when the DSC device 4 is in the permission mode, the ECU 6 sets a threshold value t2 lower than the threshold value t1 instead of the threshold value t1, and therefore, independently of the depression operation of the brake pedal 10 by the occupant. The brake hydraulic pressure Pb can be maintained, the idling stop operating region of the idling stop device 2 can be expanded while ensuring the stop state maintaining function of the vehicle V, and the fuel efficiency improvement effect can be enhanced.

  The ECU 6 includes a shift position sensor 61 that detects a gear-in state in which the driving torque of the engine 7 can be transmitted to the driving wheels, and an accelerator sensor 52 that detects a depression operation of the accelerator pedal 14. The ECU 6 is in the gear-in state and the accelerator pedal 14. Since the engine 7 is restarted via the idle stop device 2 when the stepping operation is detected, the starting characteristic of the vehicle V from the time of engine restart can be improved.

  The ECU 6 has an Eng control unit 6a capable of determining the stable state of the driving force of the engine 7, and the ECU 6 detects the brake hydraulic pressure via the DSC device 4 when the driving force is stable and the depression operation of the accelerator pedal 14 is detected. Since Pb is released, it is possible to prevent the vehicle V from unexpectedly popping out.

  Since the DSC device 4 holds the brake fluid pressure Pb when the brake fluid pressure Pb corresponding to the depression operation of the brake pedal 10 exceeds the threshold value t3 set lower than the threshold value t2, the DSC device 4 is adapted to the occupant's intention to start. The start characteristic of the vehicle V can be obtained.

Next, a modified example in which the embodiment is partially changed will be described.
1] In the above embodiment, the vehicle that executes the idle stop control as a standard has been described as an example, but the idle stop control is performed similarly to the auto hold switch that selectively switches the auto hold control between the permission mode and the prohibition mode. An idle stop switch that selectively switches between the permission mode and the prohibition mode may be provided.

2] In the above-described embodiment, the example in which the idle stop execution threshold value t2 of the brake fluid pressure Pb in the prohibit mode is set to a fixed value has been described, but the threshold value t2 that is at least smaller than the threshold value t1 may be used. It is good also as a fluctuation value according to ten operation states.
For example, the start characteristic can be further enhanced by setting the threshold value t2 to be larger as the depression speed of the brake pedal 10 is higher. By setting the threshold value t2 to be smaller as the depression speed of the brake pedal 10 is faster, fuel efficiency can be further improved.
Further, the threshold value t2 may be a variation value depending on the road surface gradient.
Specifically, in the case of a front-end stop, by setting the threshold value t2 to be larger as the gradient is larger, jumping out can be avoided and safety can be improved.

3) In the above-described embodiment, the example in which the DSC control unit and the EPB control unit are integrated into the ECU has been described. However, the DSC control unit and the EPB control unit are independent of the ECU, and the DSC device and the EPB device are installed. Each may be configured. In this case, each stop mode execution command is output from the ECU to the DSC control unit and the EPB control unit, respectively.
It is also possible to integrally form the pressurizing unit and the DSC control unit and directly output the execution command for the first stop mode from the ECU to the pressurizing unit.

4) In addition, those skilled in the art can implement the present invention with various modifications added without departing from the spirit of the present invention, and the present invention includes such modifications. is there.

V Vehicle 1 Stop maintenance device 2 Idle stop device 4 DSC device 6 ECU
6a Eng control unit 10 Brake pedal 11 Wheel 14 Accelerator pedal 52 Accelerator sensor 60 Auto hold switch 61 Shift position sensor Pb Brake fluid pressure t1 to t3 Threshold value

Claims (4)

An automatic stop / restart mechanism capable of automatically stopping / restarting the engine according to the driving state of the engine in a state where the engine driving torque can be transmitted to the driving wheel, and the brake fluid pressure can be controlled to brake the wheel, and A braking force control mechanism that maintains a brake fluid pressure in response to an operation of the brake pedal, and an automatic stop / restart mechanism that is activated when a brake fluid pressure in response to a depression operation of the brake pedal exceeds a first threshold value. In a vehicle stop maintaining device comprising a control means for stopping the engine,
A switching means capable of switching between a permission mode for permitting the operation of the braking force control mechanism and a prohibit mode for not permitting,
The control means sets a second threshold value lower than the first threshold value instead of the first threshold value when the braking force control mechanism is in a permission mode. Gear-in state detecting means for detecting a gear-in state in which the driving torque of the engine can be transmitted to the drive wheels;
An accelerator pedal operation detecting means for detecting the depression operation of the accelerator pedal,
2. The vehicle stop maintaining device according to claim 1, wherein the control unit restarts the engine via the automatic stop / restart mechanism when a depression of the accelerator pedal is detected in a gear-in state. . A driving force state determining means capable of determining a stable state of the driving force of the engine;
3. The vehicle according to claim 2, wherein the control unit releases the brake hydraulic pressure via the braking force control mechanism when the driving force is stable and an accelerator pedal depression operation is detected. Stop maintenance device.   The brake force control mechanism holds the brake fluid pressure when a brake fluid pressure corresponding to a depression operation of a brake pedal exceeds a third threshold value set lower than the second threshold value. The vehicle stop maintenance device according to any one of 1 to 3.

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