JP2001163197A - Vehicle with brake force holding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle with a brake force holding device capable of smoothly starting the vehicle with a simple structure, regardless of the grade of a place where the vehicle stops. SOLUTION: This vehicle is equipped with a brake force holding device to continuously apply the brake force to the vehicle until start driving force is produced in the vehicle itself even after a braking operation is released by a driver. An amount of braking operation by the driver is detected and the brake force holding device is actuated based on the release speed of the amount of brake operation in this vehicle with a brake force holding device. The brake force holding device is actuated, on condition that the release speed of the amount of brake operation exceeds a designated value. As the release speed of the amount of the brake operation gets bigger, the brake force holding device applies bigger brake force to the vehicle. The brake force holding device gradually reduces brake force applied to the vehicle, and makes a gradually reduced speed to gradually reduce the brake force less, as the release speed of the amount of brake operation gets bigger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle equipped with a braking force holding device having a braking force holding device for continuously applying a braking force to a vehicle even after the driver releases the brake operation when the vehicle is stopped.

[0002]

2. Description of the Related Art A brake force holding device having a brake force holding device capable of continuously applying a braking force to a vehicle even after the driver releases the brake operation when the vehicle stops, until a start driving force is generated in the vehicle itself. Vehicles are known. Some brake force holding devices are provided with an electromagnetic valve in a hydraulic passage between a master cylinder and a wheel cylinder, and communicate / shut off the hydraulic passage with an electromagnetic valve to hold a braking force. In the vehicle with the brake force holding device, even after the depression of the brake pedal is released, the hydraulic pressure passage is shut off by the solenoid valve and the brake hydraulic pressure is held in the wheel cylinder. When the start operation is performed, the shutoff of the hydraulic passage by the electromagnetic valve is released, so that the vehicle can start smoothly without retreating on an uphill.

For example, Japanese Patent Application Laid-Open No. Sho 60-12360 discloses that an electromagnetic check valve is provided between a master cylinder and a wheel cylinder, and the electromagnetic check valve is operated so that brake fluid from the wheel cylinder to the master cylinder is moved. There is disclosed a vehicular braking device that holds a braking force by preventing backflow of the vehicle. The operation condition or the release condition of the electromagnetic check valve is determined by an electronic control unit based on signals from various detection devices such as a vehicle speed sensor, an accelerator pedal switch, and a brake pedal switch. Further, for example, Japanese Patent Application Laid-Open
Japanese Patent Application Laid-Open No. 202202/1992 has a brake force applying means and a driving force detecting means capable of applying a braking force to a vehicle regardless of a driver's braking operation, and when the driver releases the brake pedal from a state in which the driver depresses the brake pedal. To
A braking force control device for a vehicle including a starting clutch that controls a braking force application unit to maintain a braking force until the driving force is switched from a small state to a large state is disclosed.

[0004]

However, the control of the braking force in the above-mentioned braking force control device or the like maintains the braking force regardless of whether the vehicle is stopped on an uphill or a downhill. I do. For this reason,
On a downhill, there is a problem that when the driver tries to move forward at a low speed (slow speed advance by the own weight of the vehicle) by loosening the depression of the brake pedal, the driver cannot start smoothly. It is a useless operation to hold the braking force on a downhill where it is not necessary to hold the braking force. Furthermore, even when traveling uphill, a constant braking force is maintained regardless of the gradient of the place where the vehicle is stopped.
Excessive or insufficient braking force occurs with respect to the actual vehicle state, and there is a problem in terms of smooth starting of the vehicle.

In Japanese Patent Application Laid-Open No. 63-43854, an electromagnetic valve is provided between a master cylinder and a wheel cylinder, and the brake fluid pressure is held in the wheel cylinder by energizing the electromagnetic valve from the electromagnetic valve control means. A control device for a brake fluid pressure holding device is disclosed. The electromagnetic valve control means energizes the electromagnetic valve based on signals from the inclination detecting means, the brake switch, the clutch switch, and the reverse gear switch when the vehicle stops on the uphill while moving forward or backward. By providing the inclination detecting means in this way,
Unnecessary holding of the braking force on a downhill is prohibited, and smooth slow speed advance is enabled by loosening the brake pedal. However, in order to detect an uphill slope (uphill) or a downhill slope (downhill), a special slope detection unit is required, and in order to determine the traveling direction of the vehicle,
Requires a signal from the reverse gear switch. Further, the inclination detecting means detects whether the inclination is an upward inclination (uphill) or a downward inclination (downhill), and cannot detect the inclination (degree of inclination). Therefore, a constant braking force is maintained on an uphill irrespective of the gradient. For this reason, the braking force is excessive or insufficient with respect to the actual vehicle state, and an unsolved problem remains from the viewpoint of smooth starting of the vehicle.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems with a simple structure and to provide a vehicle with a brake force holding device capable of smoothly starting the vehicle.

[0007]

In order to solve the above-mentioned problems, the present inventors have made intensive studies and found that there is a certain relationship between the driver's braking operation and the gradient of the place where the vehicle is about to start. And completed the present invention. In other words, the vehicle with the brake force holding device according to the present invention that has solved the above-mentioned problem is a brake force holding device that continuously applies a braking force to the vehicle even after the driver releases the brake operation until the vehicle itself generates a starting drive force. Wherein the brake operation amount of the driver is detected, and the brake force holding device is operated based on the release speed of the brake operation amount.

According to the vehicle with the brake force holding device,
At the time of starting the vehicle, the brake force holding device is operated based on the release speed of the brake operation amount when the driver releases the depression of the brake pedal, and applies the brake force (holds the brake force). Then, when the starting drive force is generated in the vehicle itself, the holding of the braking force by the braking force holding device is released. In addition, the braking force may be held larger if the release speed of the brake operation amount is large, and may be kept small if the release speed of the brake operation amount is small (according to the braking force). Including not holding). Further, based on the release speed of the brake operation amount, two stages of a case where the braking force is held and a case where the braking force is not held (when the braking force holding device is not operated) may be set (three stages of large, medium and small). And so on).

Here, the release speed of the brake operation amount is obtained by calculating the brake operation amount when the driver releases the depression of the brake pedal for each unit time (every minute time) (the time differential value of the brake operation amount). ), The release speed of the brake operation amount is strongly related to the gradient of the place where the vehicle is stopped. That is, since the vehicle retreats on an uphill, the driver tries to depress the brake pedal quickly and depress the accelerator pedal. Therefore,
The release speed of the brake operation amount on an uphill is increased. On the other hand, on a downhill, the vehicle moves forward by its own weight, and thus the brake pedal is gradually released to control the vehicle. Therefore, the release speed of the brake operation amount on a downhill becomes small. On a flat ground, depressing the brake pedal is released at a medium speed, so the release speed of the brake operation amount is medium. This is the same whether the vehicle is traveling uphill or downhill with the forward gear (gear position of the transmission). The same applies when going uphill or downhill in reverse gear. Therefore, according to this configuration, when climbing an uphill, a large braking force acts on the vehicle even after the brake operation is released (after the brake pedal is depressed and released), and the vehicle can start without retreating. Also, when descending downhill, a small braking force (including zero) is applied, and a slow speed advance can be performed by loosening the depression of the brake pedal (when the forward force due to its own weight exceeds the retained brake force). ). In addition, in this configuration, the inclination detecting means and the reverse gear switch are not particularly required.

Incidentally, the release speed of the brake operation amount is:
Brake pedals such as when the brake pedal is released from being depressed strongly, when it is released from being depressed moderately, when it is released from being depressed loosely, etc. There is an advantage that it can be obtained without being affected by the depressed state (stroke).

Further, the vehicle with the brake force holding device according to the present invention is characterized in that the brake force holding device is operated on condition that the release speed of the brake operation amount exceeds a predetermined value. 2). According to this configuration, when the release speed of the brake operation amount exceeds the predetermined value, that is, when the driver releases the brake pedal quickly, the brake force holding device operates and the brake force is held. . On the other hand, when the release speed of the brake operation amount is less than the predetermined value, that is, when the driver slowly releases the depression of the brake pedal on a downhill, the brake force holding device does not operate and the brake force is not held. . Therefore,
Slow forward movement by loosening the depression of the brake pedal can be performed more smoothly according to the driver's intention (based on the driver's brake pedal operation). In addition, useless operation of the brake force holding device can be eliminated.

Further, in the vehicle with a brake force holding device according to the present invention, the brake force holding device applies a larger braking force to the vehicle as the release speed of the brake operation amount increases. 3). In other words, when climbing an uphill (regardless of whether the vehicle is moving forward or backward), the steeper the slope, the more likely the vehicle is to retreat. For this reason, the driver
The steeper the slope, the sooner the brake pedal is depressed, the more the pedal is depressed, the more the accelerator pedal is depressed, and the driving force from the prime mover tries to suppress the retreat. Therefore, a greater brake force is applied to the vehicle as the release speed of the brake operation amount is increased, and a smaller brake force is applied to the vehicle as the release speed of the brake operation amount is reduced, so that the vehicle is smoothly driven regardless of the gradient (degree of gradient). Vehicle can be started. When the vehicle descends on a downhill (regardless of whether the vehicle is moving forward or backward), the vehicle generates a forward force due to its own weight. For this reason, the driver slowly releases the depression of the brake pedal and tries to control the forward force with the braking force. Therefore, in the case of such a downhill where a forward force is generated, it is preferable that the braking operation can be performed according to the driver's intention without holding the braking force. For example, the brake force holding device is not operated, or the brake force is not held even if it is operated.

In the vehicle with a brake force holding device according to the present invention, the brake force holding device gradually reduces a braking force acting on the vehicle, and the braking force is gradually reduced by the releasing speed of the brake operation amount. The larger the value is, the smaller the value is. In this way, by gradually decreasing the braking force, the driving force that increases to the starting driving force and the braking force that gradually decreases can be harmonized, and a smooth start of the vehicle can be realized. At the same time, by gradually decreasing the deceleration speed as the release speed of the brake operation amount is increased, for example, a (greater) brake force is maintained longer as a steep ascending slope is more likely to cause retreat. Therefore, until the starting drive force is generated, the vehicle can be prevented from moving backward by the braking force acting on the vehicle. On the other hand, by gradually increasing the deceleration speed as the release speed of the brake operation amount is smaller, it is possible to eliminate unnecessary brake dragging on a flat ground or a downhill. Therefore,
According to the present invention, it is possible to realize a smoother vehicle start.

[0014] The term "until the starting drive force is generated in the vehicle itself" in the claims means that there is no output of a prime mover such as an engine or a motor (a sufficient output that does not cause retreat on an uphill is generated). From the point where the vehicle does not move backward) to the point where an output that does not cause a retreat on an uphill is generated. Whether or not the starting driving force has been generated may be determined by directly measuring the driving torque of the driving wheels, but it can be determined that the starting driving force has been generated in the vehicle itself at the following time. When the accelerator pedal is depressed by the driver's operation (vehicle with an automatic transmission) When the accelerator pedal is depressed and the clutch is engaged by the driver's operation (vehicle with a manual transmission) When the increase in the torque transmission capacity of the starting clutch is increased so that the driving force automatically increases to the extent that it automatically resists the slope in response to the release of the depression of the brake pedal, when the increase is achieved (At the time of "creep rising" in the embodiment of the present application)

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a vehicle with a brake force retaining device according to the present invention will be described below in detail with reference to the drawings. The present embodiment will be described by dividing into the following three embodiments. In the first embodiment, the brake force holding device is operated on condition that the release speed of the driver's brake operation amount exceeds a predetermined value (hereinafter referred to as “threshold”).
In the second embodiment, in addition to the control of the first embodiment, a larger braking force is applied to the vehicle as the release speed of the driver's brake operation amount increases. In the third embodiment, in addition to the control of the first embodiment, as the release speed of the driver's brake operation amount increases, the speed at which the braking force is gradually reduced is reduced.

First Embodiment First, a vehicle with a braking force holding device according to the first embodiment (hereinafter referred to as "vehicle") will be described. The vehicle according to the first embodiment includes a braking force holding device that continues to hold and act on the vehicle even after the driver releases the brake operation. Then, the vehicle detects a driver's brake operation amount, and activates the brake force holding device based on the release speed of the brake operation amount (hereinafter referred to as “brake operation release speed”). However, the brake force holding device operates on condition that the brake release speed exceeds a threshold. In addition, the braking force is maintained while gradually decreasing.

Specifically, in the vehicle according to the first embodiment, when the brake operation release speed exceeds the threshold value, the braking force holding device is operated to apply a constant braking force until the vehicle starts driving force. When the brake operation release speed is equal to or less than the threshold value, the operation of the brake force holding device is prohibited and the brake force is not held. Here, the holding of the braking force is performed by holding the brake fluid pressure. This vehicle includes a driving force control device that switches the driving force of creep between a large state and a small state in accordance with the depression state of the brake pedal when the prime mover is in an idling state and at a predetermined vehicle speed or less. Here, the creep means that, when a driving range such as a D range or an R range is selected in a vehicle equipped with an automatic transmission, even if the accelerator pedal is not depressed (the prime mover is in an idling state),
That is, the vehicle moves slowly as if crawling.

{System Configuration of Vehicle etc.} The system configuration of the vehicle according to the first embodiment will be described with reference to FIG. 1 and FIG. FIG. 1 is a system configuration diagram of a vehicle according to the first embodiment, and FIG. 2 is a configuration diagram of a vehicle brake force holding device according to the first embodiment. The vehicle according to the first embodiment is a hybrid vehicle including an engine 1 which is an internal combustion engine powered by gasoline or the like as a prime mover and a motor 2 powered by electricity, and a belt-type continuously variable transmission as a transmission. 3 (hereinafter, referred to as CVT3). In the vehicle of the present invention, the prime mover is not particularly limited, such as only the engine or only the motor as the prime mover. Further, the transmission is not particularly limited, such as an automatic transmission or a manual transmission including a torque converter as the transmission.

[Engine (Motor) / CVT (Transmission)
[Motor (Motor)] The engine 1 is controlled by a fuel injection electronic control unit (hereinafter referred to as FIECU). The FIECU is configured integrally with a management electronic control unit (hereinafter referred to as MG ECU),
Electronic control unit for fuel injection / management (hereinafter referred to as F
I / MG ECU 4). Also,
The motor 2 is a motor electronic control unit (hereinafter referred to as “MOTE”).
CU). In addition, CVT3
Is controlled by a CVT electronic control unit (hereinafter referred to as CVT ECU) 6.

Further, a drive shaft 7 on which drive wheels 8, 8 are mounted is mounted on the CVT 3. The drive wheels 8, 8 are provided with disc brakes 9, 9 having a wheel cylinder WC (see FIG. 2) and the like. The master cylinder MC is connected to the wheel cylinders WC of the disc brakes 9, 9 via a braking force holding device RU.
The depression from the brake pedal BP is transmitted to the master cylinder MC via the master power MP. The brake switch BP detects whether the brake pedal BP is depressed or not.

The engine 1 is an internal combustion engine that utilizes heat energy, and drives the drive wheels 8 via a CVT 3 and a drive shaft 7. In some cases, the engine 1 is automatically stopped when the vehicle stops to prevent deterioration of fuel efficiency. For this purpose, the vehicle includes a motor stopping device that stops the engine 1 when an engine automatic stop condition is satisfied.

The motor 2 has an assist mode for assisting driving by the engine 1 by using electric energy from a battery (not shown). The motor 2 has a regenerative mode in which kinetic energy due to rotation of the drive shaft 7 is converted into electric energy when assist is not required (during downhill, deceleration, etc.), and stored in a battery (not shown). It has a starting mode for starting.

The CVT 3 changes the speed ratio steplessly by winding an endless belt between a drive pulley and a driven pulley, and changing the width of each pulley to change the winding radius of the endless belt. And CVT3
Connects the start clutch to the output shaft, engages the start clutch, and transmits the output of the engine 1 or the like shifted by the endless belt to the drive shaft 7 via the output gear of the start clutch. The vehicle equipped with the CVT 3 is capable of creep running at the time of idling and includes a driving force control unit DCU that reduces the driving force of the creep.

[Driving force control unit] Driving force control unit DCU
Is provided in the CVT 3 and variably controls the driving force transmission capacity of the starting clutch to switch the magnitude of the creep driving force. Further, when detecting the vehicle movement (or the vehicle retreat), the driving force control device DCU increases the driving force. Note that the driving force control unit DCU includes a CV described later.
The TECU 6 is also included in the configuration.

The driving force control unit DCU includes a condition for setting a weak creep state, a condition for setting a medium creep state, which will be described later,
The CVT ECU 6 determines the conditions for setting the strong creep state and the conditions for setting the strong creep state during running, and changes the driving force transmission capacity of the starting clutch to switch to the preset driving force in each creep state. Further, the driving force control unit DCU
When detecting whether the vehicle has retreated or the vehicle has moved when starting uphill, the vehicle increases the driving force transmission capacity of the starting clutch and switches to the strong creep state. The driving force control unit DCU determines each condition for switching the creep driving force by the CVT ECU 6, and sends the CVT ECU 6 to the CVT 3
To the linear solenoid valve for controlling the hydraulic pressure applied to the starting clutch. Then, the driving force control unit DCU switches the engagement force of the starting clutch based on the hydraulic pressure command value in the CVT 3. As a result, the driving force transmission capacity also changes, and the driving force for creep switches. In the vehicle, fuel efficiency is improved by reducing the driving force by the driving force control device DCU. Improvements in fuel economy
This is realized by reducing the load on the engine 1 and the load on the hydraulic pump in the starting clutch. Here, the driving force transmission capacity means the maximum driving force (driving torque) that can be transmitted by the starting clutch. That is, when the driving force generated by the engine 1 exceeds the driving force transmission capacity, the starting clutch applies the driving force exceeding the driving force transmission capacity to the driving wheels 8, 8.
Cannot be transmitted to By the way, the failure detection device D
When the failure of the braking force holding unit RU is detected in U, the switching to the weak creep state by the driving force control unit DCU is prohibited.

The driving force control unit DCU transmits the driving force from the prime mover to the driving wheels when the driving range is selected in the transmission even when the accelerator pedal is not depressed at a predetermined vehicle speed or less, and When the brake pedal BP is depressed, the driving force transmitted to the drive wheels is set to “small state”, and when the brake pedal BP is not depressed, the driving force is set to “large state”. To The reason why the driving force is set to the “small state” when the brake pedal BP is depressed is to suppress vehicle body vibration caused by controlling the driving force with the braking force. In addition, even if the driver depresses the brake pedal BP strongly and the driving force by the engine 1 disappears, the vehicle does not move backward due to its own weight when stopping on a slope. on the other hand,
The reason why the driving force is set to the “large state” when the brake pedal BP is released is to prepare for starting and acceleration of the vehicle and to be able to withstand a certain amount of slope without relying on the braking force.

The driving force for creep of the vehicle according to the present embodiment has three magnitudes, that is, a large state and a small state, and an intermediate state between the large state and the small state. The driving force transmission capacity in each state is preset to be large when the driving force is large, small when the driving force is small, and to an intermediate value when the driving force is an intermediate value. In this embodiment, a state in which the driving force (driving force of creep) is large is a strong creep state, a state in which the driving force is small is a weak creep state, and a state in which the driving force is intermediate between the large state and the small state is medium creep. Called state. Further, the strong creep state includes a level at which the driving force is large and a level at which the driving force is small. A large level is simply called a strong creep state, and a small level is called a strong creep state during running. The strong creep state is a state having a driving force that balances a gradient of 5 °. The strong creep condition during running is
The driving force is smaller than the strong creep state, and is a state before switching to the weak creep state. The weak creep state is a state where there is almost no driving force. Medium creep condition
This is a state in which the driving force is intermediate between the strong creep state and the weak creep state, and is an intermediate state in which the driving force is reduced stepwise in the process of switching from the strong creep state to the weak creep state. The strong creep state is realized when the depression of the accelerator pedal is released at a predetermined vehicle speed or less (that is, in the idling state) and the travel range is selected by the position switch PSW, and the vehicle is released when the depression of the brake pedal BP is released. Crawls slowly. In the weak creep state, the brake pedal BP
Is realized when is depressed, and the vehicle is stopped or at a very low speed.

[Position Switch] The range of the position switch PSW is selected by a shift lever. The range of the position switch PSW is P
There are a range, an N range that is neutral, an R range used during reverse running, a D range used during normal running, and an L range used when sudden acceleration or strong engine braking is required. In the present embodiment, the travel ranges refer to three ranges of a D range, an L range, and an R range in which the vehicle can travel. Further, in the present embodiment, when the D range is selected by the position switch PSW, the mode switch MSW can select the D mode as the normal driving mode and the S mode as the sports driving mode. Incidentally, information on the position switch PSW and the mode switch MSW is transmitted to the CVT ECU 6 and further transmitted to the meter 10. The meter 10
The range information and the mode information selected by the position switch PSW and the mode switch MSW are displayed. In the present embodiment, the above-described reduction of the creep driving force (that is, the driving force is set to the middle creep state or the weak creep state) is performed when the position switch PSW is in the D range or the L range. When in the R range, the strong creep state is maintained. In the N range and the P range, the driving force is not transmitted to the driving wheels 8, 8, but the driving force transmission capacity is reduced and the mode is switched to a weak creep state in terms of form. These points will be described later in detail.

[ECUs] The FIECU included in the FI / MG ECU 4 controls the fuel injection amount so as to obtain an optimum air-fuel ratio, and controls the engine 1 as a whole. The FIECU is transmitted with information indicating the throttle opening and the state of the engine 1, and controls the engine 1 based on each information. Also, M included in FI / MG ECU 4
The GECU mainly controls the MOTECU 5 and determines an automatic engine stop condition and an automatic engine start condition. The MGECU receives information indicating the state of the motor 2 and also receives information indicating the state of the engine 1 from the FIECU, and instructs the MOTECU 5 to switch the mode of the motor 2 based on each piece of information. Also, information indicating the state of the CVT 3 is stored in the MG ECU.
Information indicating the state of the engine 1, the position switch PS
W range information, information indicating the state of the motor 2 and the like are transmitted, and the automatic stop or automatic start of the engine 1 is determined based on each information.

The MOTECU 5 controls the motor 2 based on a control signal from the FI / MG ECU 4. FI /
The control signal from the MGECU 4 includes mode information for instructing starting of the engine 1 by the motor 2, assisting the driving of the engine 1 or regenerating electric energy, an output request value for the motor 2, and the like. A command is issued to the motor 2 based on the instruction. Further, information is obtained from the motor 2 and the like, and information on the motor 2 such as the amount of power generation and the capacity of the battery are transmitted to the FI / MG ECU 4.

The CVT ECU 6 controls the speed ratio of the CVT 3 and the driving force transmission capacity of the starting clutch. CVTE
The CU 6 receives information indicating the state of the CVT 3, information indicating the state of the engine 1, range information of the position switch PSW, and the like, and controls the hydraulic pressure of each cylinder of the drive pulley and the driven pulley of the CVT 3 and the hydraulic pressure of the starting clutch. To the CVT 3. Further, the CVT ECU 6 controls the braking force holding device R
ON of solenoid valves SV (A) and SV (B) of U (see FIG. 2)
A control unit CU for controlling (interruption) / OFF (communication) is provided, and the solenoid valves SV (A) and SV (B) are turned ON (interruption) / O.
In order to perform FF (communication), the brake force holding device RU is energized. In addition, the CVT ECU 6 determines the switching of the driving force of the creep, and when the vehicle movement (or the vehicle retreats) is detected during the operation of the braking force holding device RU, determines that the driving force is increased. Information
This is transmitted to the driving force control unit DCU of the VT3. Also, CV
The TECU 6 includes a failure detection device DU for detecting a failure of the braking force holding device RU. In addition, CV
The TECU 6 determines whether or not to switch the driving force of creep and determines whether to increase the driving force when vehicle movement (or vehicle retreat) is detected, and based on the determination result, controls the engagement hydraulic pressure of the starting clutch. Transmits the oil pressure command value to the solenoid valve.

[Brake (braking force holding device)] The disk brakes 9, 9 are provided with a wheel rotor WC (see FIG.
(See FIG. 2) as a drive source, and a braking force is obtained by the frictional force. The brake fluid pressure of the master cylinder MC is supplied to the wheel cylinder WC via the brake force holding device RU.

The brake force holding device RU keeps the brake force by applying the brake fluid pressure to the wheel cylinder WC even after the brake pedal BP is released. The brake force holding device RU includes a control unit CU in the CVT ECU 6 in its configuration. This braking force holding device RU
Will be described later in detail (see FIG. 2).

Note that the ON / OFF of the solenoid valve means that
"In a normally open solenoid valve, when the solenoid valve is turned on, it means that the solenoid valve is closed and it is in a shut-off position where the flow of brake fluid is shut off. To be a communication position that allows for ".
On the other hand, in a normally-closed solenoid valve, when the solenoid valve is turned on, the solenoid valve is opened and the communication position allows the flow of the brake fluid. When the solenoid valve is turned off, the solenoid valve is closed and the brake fluid is closed. To a blocking position to block the flow of air. " As will be described later, the solenoid valves SV (A) and SV (B) in the present embodiment are normally-open solenoid valves (proportional solenoid valves). The drive circuit provided in the control unit CU turns on / off the solenoid valves SV (A) and SV (B).
In order to perform this operation, the amount of current flowing through each solenoid coil of the solenoid valves SV (A) and SV (B) is calculated, and the solenoid valves SV (A) and SV (B) are calculated.
(B) is energized.

The master cylinder MC has a brake pedal B
This is a device that changes the depression of P to hydraulic pressure. Furthermore, in order to assist the depression of the brake pedal BP,
Master power MP is provided between master cylinder MC and brake pedal BP. Master power MP
The braking force is enhanced by adding a force such as a negative pressure of the engine 1 or compressed air to the force of the driver depressing the brake pedal BP,
This is a device that reduces the pedaling force during braking. The brake pedal BP is provided with a brake switch BSW.
It is detected whether P is depressed or the depression is released.

[Motor Stop Device] The motor stop device provided in this vehicle is composed of the FI / MG ECU 4, the CVT ECU 6, and the like. The prime mover stopping device can automatically stop the engine 1 when the vehicle is stopped.
The motor stop device is composed of FI / MG ECU 4 and CVT ECU
At 6, the conditions for automatically stopping the engine are determined. The engine automatic stop condition will be described later in detail. When it is determined that all of the engine automatic stop conditions are satisfied, the engine stop command is transmitted from the FI / MG ECU 4 to the engine 1, and the engine 1 is automatically stopped. The vehicle further improves fuel efficiency by automatically stopping the engine 1 by the motor stop device. Further, when the engine 1 is automatically stopped by the motor stop device, the FI / MG ECU 4 and the CVT ECU 6 determine an engine automatic start condition. When the engine automatic start condition is satisfied, the FI / MGECU 4
Sends an engine start command to CU5, and
A command to start the engine 1 is transmitted from the CU 5 to the motor 2, and the engine 1 is automatically started by the motor 2 and at the same time, brought into a strong creep state. The automatic engine start condition will be described later in detail. Incidentally, when the failure detecting device DU detects a failure of the brake force holding device RU, the operation of the motor stopping device is prohibited.

[Signals] Next, signals transmitted and received in this system will be described. Note that “F_” added before each signal in FIG. 1 indicates that the signal is flag information of 0 or 1, and “V_” indicates that the signal is numerical information (unit is arbitrary). "I_" indicates that the signal is information including a plurality of types of information.

The signal transmitted from FI / MG ECU 4 to CVT ECU 6 will be described. V_MOTTRQ
Is the output torque value of the motor 2. F_MGSTB
Is a flag determined by the FI / MG ECU 4 in the engine automatic stop condition, and is a flag indicating whether or not all of the conditions are satisfied. The flag is 1 when the condition is satisfied, and is 0 when the condition is not satisfied. The engine automatic stop condition of F_MGSTB will be described later in detail. By the way, F
When both _MGSTB and F_CVTOK are switched to 1, the engine 1 is automatically stopped, and when either flag is switched to 0, the engine 1 is automatically started.

The signals transmitted from FI / MG ECU 4 to CVT ECU 6 and MOTECU 5 will be described. V
_NEP is the rotation speed of the engine 1.

The signal transmitted from CVT ECU 6 to FI / MG ECU 4 will be described. F_MCRPON
Is a flag indicating whether or not the vehicle is in a medium creep state,
The value is 1 when in the middle creep state, and 0 when not in the middle creep state. When F_MCRPON is 1, the engine 1 is required to blow medium air (air weaker than strong creep) in the medium creep state. F_AIRSC
RP is a strong air request flag in a strong creep state,
The value is 1 when strong air is blown in the strong creep state, and 0 when strong air is not blown. Note that F_MCRPON and F_AI
When both RSCRP are 0, FI / MG ECU 4 blows weak air in the weak creep state. By the way, in order to keep the engine speed constant during idling regardless of the strong creep state, medium creep state, and weak creep state, blow air according to each state of strong creep state, middle creep state, weak creep state It is necessary to adjust the engine output. When the load of the engine 1 is high as in the strong creep state, it is necessary to blow strong air (strong air in the strong creep state). Note that blowing air means sending air from an air passage bypassing a throttle valve of the engine 1 to an intake pipe downstream of the throttle valve. The strength of the air is controlled by controlling the opening degree of the air passage to adjust the strength (amount) of the air to be sent. F_CVTOK is a flag that is determined by the CVT ECU 6 among the automatic engine stop conditions, and is a flag indicating whether or not all of the conditions are satisfied. The engine automatic stop condition of F_CVTOK will be described later in detail. F_CVTTO is CVT3
Is a flag indicating whether the oil temperature is equal to or higher than a predetermined value, and is 1 when the oil temperature is equal to or higher than the predetermined value, and is 0 when the oil temperature is lower than the predetermined value. In addition,
The oil temperature of the CVT 3 is estimated from the electric resistance value of the linear solenoid valve that controls the hydraulic pressure of the starting clutch of the CVT 3. F_POSR is a flag indicating whether the R range is selected in the range of the position switch PSW, and is 1 for the R range and 0 for other than the R range. F_POSDD is D range in the range of the position switch PSW and D in the mode of the mode switch MSW.
A flag indicating whether the mode has been selected.
The value is 1 in the case of the range D mode, and 0 in cases other than the D range D mode. When information indicating the D range D mode, the R range, the P range, and the N range has not been input, the FI / MGECU 4 determines that one of the D range S mode and the L range has been selected.

From engine 1 to FI / MG ECU 4 and CV
The signal transmitted to the TECU 6 will be described. V_A
NP is a negative pressure value of the intake pipe of the engine 1. V_TH
Is the throttle opening. V_TW is engine 1
Is the cooling water temperature. V_TA is the intake air temperature of the engine 1. Note that the brake fluid temperature of the braking force holding device RU disposed in the engine room is estimated based on the intake air temperature. This is because both change in relation to the temperature of the engine room.

From CVT 3 to FI / MG ECU 4 and CVT
The signal transmitted to the ECU 6 will be described. V_VS
P1 is a vehicle speed pulse output from one of two vehicle speed pickups provided in CVT3. The vehicle speed is calculated based on the vehicle speed pulse.

The signal transmitted from CVT 3 to CVT ECU 6 will be described. V_NDRP is a pulse indicating the rotation speed of the drive pulley of the CVT 3. V_NDN
P is a pulse indicating the rotation speed of the driven pulley of the CVT 3. V_VSP2 is a vehicle speed pulse output from the other of the two vehicle speed pickups provided in CVT3. Note that V_VSP2 has higher accuracy than V_VSP1, and is used for calculating the slip amount of the starting clutch of the CVT3.

The signal transmitted from MOTECU 5 to FI / MG ECU 4 will be described. V_QBAT is the remaining capacity of the battery. V_ACTTRQ is the motor 2
, Which is the same value as V_MOTTRQ. I_MOT is information such as a power generation amount of the motor 2 indicating an electric load. In addition, all the electric power consumed by this vehicle including the motor driving electric power is generated by the motor 2.

The signal transmitted from FI / MG ECU 4 to MOTECU 5 will be described. V_CMDPWR
Is an output request value for the motor 2. V_ENGT
RQ is an output torque value of the engine 1. I_MG
Is information such as a start mode, an assist mode, and a regenerative mode for the motor 2.

From master power MP to FI / MG ECU 4
Will be described. V_M / PNP
Is a negative pressure detection value of the constant pressure chamber of the master power MP.

From position switch PSW to FI / MG
The signal transmitted to the ECU 4 will be described. Only when either the N range or the P range is selected with the position switch PSW, N or P
Is sent.

The signal transmitted from CVT ECU 6 to CVT 3 will be described. V_DRHP is a hydraulic pressure command value for the linear solenoid valve that controls the hydraulic pressure of the cylinder of the drive pulley of the CVT 3. V_DNHP is CVT
This is a hydraulic command value to the linear solenoid valve that controls the hydraulic pressure of the cylinder of the driven pulley No. 3. Note that V_DRH
The gear ratio of CVT3 is changed by P and V_DNHP.
V_SCHP is a hydraulic pressure command value to the linear solenoid valve that controls the hydraulic pressure of the starting clutch of CVT3. In addition,
V_SCHP changes the engaging force of the starting clutch (that is, the driving force transmission capacity).

From the CVT ECU 6 to the brake force holding device R
The signal transmitted to U will be described. V_SOLA
Is the solenoid valve SV (A) of the brake force holding device RU (FIG. 2)
This is the amount of current flowing through the electromagnetic coil to turn ON (close) / OFF (open). V_SOLB turns on the solenoid valve SV (B) (see FIG. 2) of the braking force holding device RU.
This is the amount of current flowing through the electromagnetic coil for (closed) / OFF (open). It should be noted that the control current I described later is
_SOLA and V_SOLB themselves.

From position switch PSW to CVTEC
The signal transmitted to U6 will be described. Which position of the N range, P range, R range, D range or L range is selected by the position switch PSW,
Sent as position information.

Mode switch MSW to CVT ECU 6
Will be described. Mode switch M
Whether the D mode (normal running mode) or the S mode (sports running mode) is selected by SW is transmitted as mode information. The mode switch MSW
Is a mode selection switch that functions when the position switch PSW is set to the D range.

From the brake switch BSW to FI / MGE
The signals transmitted to the CU 4 and the CVT ECU 6 will be described. F_BKSW indicates whether the brake pedal BP is depressed (ON) or the depression is released (OF
F) is a flag that indicates 1) if it is depressed,
It is 0 when the depression is released.

The signal transmitted from CVT ECU 6 to meter 10 will be described. Which position of the N range, P range, R range, D range or L range is selected by the position switch PSW is transmitted as position information. Further, D is set by the mode switch MSW.
Whether the mode (normal driving mode) or the S mode (sports driving mode) is selected is transmitted as mode information.

From the brake operation amount detector BG to CVTEC
The signal transmitted to U6 will be described. V_BG is
The brake operation amount of the driver is transmitted to the CVT ECU 6 as a brake fluid pressure value on the master cylinder MC side. Based on this signal, a brake operation release speed and the like are obtained (these points will be described later).

In addition to the flags shown in FIG. 1, the flag includes F_BKTH which is used by the control unit CU to determine whether to maintain the braking force (see FIGS. 3 and 6 (a)). The control unit CU sets F_BKTH to 1 when the brake operation release speed exceeds the threshold value while the brake switch BSW is ON. Further, the control unit CU includes a brake switch BS.
When W is turned off or when brake pedal B
When P is further depressed (when the brake release speed becomes a negative value), F_BKTH is set to 0. This F
The control unit CU performs the holding of the braking force, the release of the holding of the braking force, and the like by _BKTH. Specific control will be described later.

<< Brake Force Holding Device >> [Structure of Brake Force Holding Device] Brake Force Holding Device RU
Detects a driver's brake operation amount, and applies a braking force to the vehicle based on the brake operation release speed until the vehicle itself generates a starting drive force even after the driver releases the brake operation. However, the brake force holding device operates on condition that the brake release speed exceeds a threshold, and holds the brake force.

As shown in FIG. 2, the vehicle brake force holding device RU according to the first embodiment is incorporated in a brake hydraulic pressure passage FP of a hydraulic brake device BK, and is provided between the master cylinder MC and the wheel cylinder WC. And a solenoid valve SV that switches to a communication position for communicating with the brake fluid pressure passage FP and a blocking position for blocking the brake fluid pressure passage FP and retaining the brake fluid pressure of the wheel cylinder WC (that is, retaining the braking force). The amount of current flowing through an electromagnetic coil (not shown) of the solenoid valve SV is controlled by the control unit CU.
Switch to the communication position and the cutoff position according to the amount of current, and reduce (gradual decrease) while adjusting the held brake fluid pressure
can do.

First, the hydraulic brake device BK will be described, and then the brake force holding device RU will be described (both refer to FIG. 2). The brake hydraulic circuit BC of the hydraulic brake device BK includes a master cylinder MC and a wheel cylinder W.
C and a brake fluid pressure passage FP connecting it. Brakes play a crucial role in driving safely,
The hydraulic brake device BK has two independent brake hydraulic circuits (BC (A) and BC (B)) so that even if one system fails, the remaining system can obtain the minimum braking force. It has become.

The master cylinder MC has a piston M
The CP is inserted, and when the driver depresses the brake pedal BP, the piston MCP is pressed and pressure is applied to the brake fluid in the master cylinder MC, and mechanical force is reduced to brake fluid pressure (pressure applied to the brake fluid). Is converted. When the driver releases his / her foot from the brake pedal BP to release the depression, the piston MCP is actuated by the force of the return spring MCS.
Is restored, and at the same time, the brake fluid pressure also returns. The master cylinder MC shown in FIG. 2 has two pistons MCP arranged side by side from the viewpoint of fail-safe that two independent brake hydraulic circuits BC are provided.
Is a tandem type master cylinder MC obtained by dividing the main body into two parts.

In order to reduce the operating force of the brake pedal BP, a master power MP (brake booster) is provided between the brake pedal BP and the master cylinder MC.
The master power MP shown in FIG. 2 is of a vacuum (negative pressure) servo type, in which a negative pressure is extracted from an intake manifold of the engine 1 and a brake pedal BP by a driver.
The operation is easy.

The brake fluid pressure passage FP connects the master cylinder MC and the wheel cylinder WC and the master cylinder M
The brake fluid pressure generated in C serves as a flow path for transmitting the brake fluid to the wheel cylinder WC by moving the brake fluid. Further, when the brake fluid pressure of the wheel cylinder WC is higher, it serves as a flow path for returning the brake fluid from the wheel cylinder WC to the master cylinder MC. As described above, the brake fluid pressure circuits BC are provided independently of each other, so that two independent brake fluid pressure passages FP are provided. The brake hydraulic circuit BC constituted by the brake hydraulic passage and the like shown in FIG.
One brake hydraulic circuit BC (A) brakes the right front wheel and the left rear wheel, and the other brake hydraulic circuit BC (B) brakes the left front wheel and the right rear wheel. Note that the brake hydraulic circuit may be of a front-rear split type in which one brake hydraulic circuit brakes both front wheels and the other brake hydraulic circuit brakes both rear wheels, instead of the X piping system.

The wheel cylinder WC is provided for each wheel 8, and uses a brake fluid pressure generated by the master cylinder MC and transmitted to the wheel cylinder WC through the brake fluid pressure passage FP to a mechanical force for braking the wheel 8. (Braking force). Wheel cylinder W
C denotes a piston inserted into the main body, which is pressed by the brake fluid pressure to actuate a brake pad for a disk brake or a brake shoe for a drum brake to brake the wheels 8. To produce In addition to the above, the wheel cylinder WC of the front wheel
And a brake fluid pressure control valve for controlling the brake fluid pressure of the rear wheel cylinder WC and the like.

Next, a description will be given of a braking force holding device RU which is a main part of the vehicle (vehicle with a braking force holding device) of the present invention (see FIG. 2). The brake force holding device RU includes a solenoid valve SV, a check valve CV, a brake operation amount detector BG
And a control unit CU (included in the CVT ECU 6), of which the solenoid valve SV is incorporated in a brake fluid pressure passage FP connecting the master cylinder MC and the wheel cylinder WC. Incidentally, the brake force holding device RU is provided with a brake fluid pressure sensor PG in the brake fluid pressure passage FP in order to detect the brake fluid pressure of the master cylinder MC. , Also serves as a brake operation amount detector BG.

The solenoid valve SV is actuated by an electric signal from the control unit CU, and the brake hydraulic pressure passage F
There is a blocking state in which the flow of the brake fluid of P is blocked, and a communication state in which the flow of the brake fluid in the brake fluid pressure passage FP is allowed at the communication position (OFF). Furthermore, the solenoid valve SV
The brake fluid pressure is adjusted while switching between the blocking position (ON) and the communication position (OFF) to repeatedly block / allow the flow of the brake fluid in the brake fluid passage FP. Incidentally, two solenoid valves SV (A), shown in FIG.
SV (B) indicates that both are at the communication position. The solenoid valve SV allows the driver to operate the brake pedal B when starting uphill.
Even if the depression of P is released, the wheel cylinder W
By holding the brake fluid pressure at C, it is possible to prevent the vehicle from moving backward. Note that retreating means that the vehicle travels in a direction opposite to the direction in which the driver intends to travel due to the weight of the vehicle (going down a slope).

When the solenoid valve SV is switched to the shut-off state, the flow of the brake fluid is shut off at once, and the brake fluid pressure applied to the wheel cylinder WC is held as the braking force. Therefore, the brake force holding device RU can hold the brake fluid pressure sent to the wheel cylinder WC as it is by switching the solenoid valve SV to the shut-off state. By the way, wheel cylinder W
The brake fluid pressure sent to C is master power MP,
This is the brake fluid pressure transmitted through the master cylinder MC and the brake fluid pressure passage FP and proportional to the driver's depression force on the brake pedal BP.

When the solenoid valve SV is switched to the communicating state, the flow of the brake fluid between the wheel cylinder WC and the master cylinder MC is allowed at once, and the braking force is instantaneously released. When the solenoid valve SV is maintained in the communication state, the wheel cylinder WC does not hold the brake fluid pressure (the brake force is not held).

When the solenoid valve SV switches to the pressure regulating state, the solenoid valve SV switches alternately and repeatedly between the shut-off position and the communication position to adjust the flow rate of the brake fluid flowing from the wheel cylinder WC to the master cylinder MC. And
The brake fluid pressure (and thus the braking force) is reduced while being adjusted, and the holding brake force is gradually reduced. As will be described later, the gradual decrease of the braking force is controlled by the control current I (V_SOLA, V_SOLB) supplied from the control unit CU to the solenoid valve SV.
Is gradually decreased (decreasing at a first decreasing rate).

In the first embodiment, when the solenoid valve SV switches from the communicating state to the shut-off state, it switches without passing through the pressure regulating state. On the other hand, the solenoid valve SV
Is switched from the cut-off state to the communication state, via the pressure regulation state. The conditions under which the solenoid valve SV switches to the shut-off state, the communication state, or the pressure regulation state will be described later in detail.

Here, as the solenoid valve SV capable of reducing the brake fluid pressure while adjusting the brake fluid pressure,
There is a proportional solenoid valve. Proportional solenoid valve (solenoid valve S in FIG. 2)
V) is, for example, the sum of the urging force of a spring S built in the valve and the product of the applied pilot pressure multiplied by the pressure receiving area (hereinafter referred to as “urging force, etc.”). The opening and closing (communication / shutoff) of the valve is repeated so as to be balanced with the electromagnetic force generated by (not shown). If the proportional solenoid valve is a normally open type, the valve opens and becomes the communication position if the biasing force or the like is larger than the electromagnetic force. The communication position is maintained until the electromagnetic force becomes greater than the urging force. On the other hand,
If the biasing force or the like is smaller than the electromagnetic force, the valve closes to the shutoff position. Further, the cutoff position is maintained until the electromagnetic force becomes smaller than the urging force. Here, the pilot pressure is a brake fluid pressure of the wheel cylinder WC.

The electromagnetic force of the proportional solenoid valve changes according to the value of the control current supplied to the electromagnetic coil. In the case of a normally open proportional solenoid valve, if this current value is gradually reduced from the large current value in the shut-off state, the electromagnetic force will also gradually weaken.
By balancing the urging force and the electromagnetic force, the brake fluid pressure can be adjusted while switching between the communication position and the blocking position. When the brake fluid pressure held in the wheel cylinder is reduced, the brake fluid pressure (that is, the braking force) can be gradually reduced by gradually reducing the current value of the control current. In the case of a normally-open proportional solenoid valve, the communication state is maintained when the value of the control current supplied to the electromagnetic coil is zero (substantially zero).

By the way, in the first embodiment, the solenoid valve SV
Is a proportional solenoid valve, but the present invention is not necessarily limited to the proportional solenoid valve, and any type of valve can be used as long as it can create the above-described shut-off state, communication state, and pressure regulation state. The solenoid valve SV includes a normally closed type which is in a communicating position when energized and a normally open type which is in a shut off position when energized, and any type of electromagnetic valve can be used.
However, from the viewpoint of fail-and-safe, a normally open solenoid valve is preferable. This is because, when the power is cut off due to a failure or the like, the brake does not work with the normally closed solenoid valve, or the brake stays working. Note that the present embodiment will be described on the assumption that the solenoid valve SV is a normally open type.

The check valve CV is provided as needed, but when the solenoid valve SV is in the shut-off position and the driver further depresses the brake pedal BP, the master cylinder MV
The brake fluid pressure generated in C is transmitted to the wheel cylinder WC. Check valve CV is connected to master cylinder M
It effectively operates when the brake fluid pressure generated at C exceeds the brake fluid pressure of the wheel cylinder WC, and quickly increases the brake fluid pressure of the wheel cylinder WC in response to the driver's increased depression of the brake pedal BP. When the brake fluid pressure of the master cylinder MC becomes higher than the brake fluid pressure of the wheel cylinder WC, the solenoid valve S is closed once.
If the configuration is such that V is in a communicating state, it is possible to cope with an increase in the depression of the brake pedal BP only with the solenoid valve SV, and thus it is not necessary to provide the check valve CV. In other words, the brake fluid pressure value on the master cylinder MC side and the brake fluid pressure value on the wheel cylinder WC side are detected, and when the former brake fluid pressure value exceeds the latter brake fluid pressure, the solenoid valve SV enters the open state. With the configuration, the check valve CV can be made unnecessary.

The brake switch BSW detects whether or not the brake pedal BP is depressed. And
This detection value is transmitted to the control unit CU.

The brake fluid pressure sensor PG is provided in the brake fluid pressure passage FP and detects the brake fluid pressure on the master cylinder MC side. As described above, the brake fluid pressure sensor PG also serves as the brake operation amount detector BG, detects the driver's brake operation amount, and transmits the detected value V_BG to the control unit CU. Incidentally, the brake fluid pressure on the master cylinder MC side detected by the brake fluid pressure sensor PG is different from the brake fluid pressure on the wheel cylinder WC side, and is proportional to the driver's brake operation amount. Therefore, with the configuration in which the brake fluid pressure sensor PG also functions as the brake operation amount detector BG, it is possible to sufficiently detect the brake operation amount of the driver. Further, the brake operation amount detector BG correctly measures the brake operation release speed regardless of whether the driver is depressing the brake pedal BP strongly, moderately, or gently. can do. The brake operation amount detector BG
Is a rotational displacement meter that detects the rotation angle of the support shaft of the brake pedal BP, one that detects the depression force of the brake pedal BP, one that detects the stroke of the brake pedal, one that detects the piston stroke of the master cylinder MC or the master power MP. It is also possible to use one that can calculate the amount of brake operation per unit time (that is, the brake operation release speed), such as the one that performs.

The control unit CU includes a brake operation amount detector BG
, The flag F_BKTH, the signal of the brake switch BSW, the vehicle speed, and the like, it is determined whether the solenoid valve SV is in the communication state, the cutoff state, or the pressure regulation state, and the brake operation release speed exceeds the threshold value. Case (F_B
KTH = 1) and the control current I (V_SOL) is supplied to the solenoid valve SV.
A, V_SOLB) to supply the braking force holding unit RU
Operate.

If the threshold value is set to a large value, there is an advantage that a brake operation that is not intended to release the driver from depressing the brake pedal BP can be cut off as noise. On the other hand, when the threshold value is set to a large value, the brake pedal BP is released by the time the brake operation release speed reaches the threshold value. There is a disadvantage that there is. Therefore, the threshold value is set by weighing the benefits and disadvantages when the threshold value is increased. Incidentally, in the case of the present embodiment, since the braking force is increased only by the driver's braking operation, if the threshold value is set to be large, the above-described inconvenience is likely to occur.

In the first embodiment, the control unit CU
Activates the brake force holding device RU when the brake release speed exceeds the threshold value. And the control unit CU,
The magnitude of the current value of the control current I for bringing the solenoid valve SV into the shut-off state is supplied to the solenoid valve SV at a constant value regardless of the magnitude of the brake release speed. And the control unit CU
Immediately and gradually reduces the current value of the control current I supplied to the solenoid valve SV at a predetermined rate (a first decreasing speed described later), and attempts to bring the solenoid valve SV into a pressure regulating state. Therefore, depending on the relationship between the current value of the control current I supplied to the solenoid valve SV and the brake fluid pressure held in the wheel cylinder WC, the control current I is supplied and the solenoid valve SV is shut off and simultaneously the pressure regulation state When the control current I is supplied, the solenoid valve SV is not immediately shut off even when the control current I is supplied (when the brake fluid pressure of the wheel cylinder WC is large), and when the control current I is supplied, the solenoid valve SV is shut off for a while. There are three cases when the state is reached (when the brake fluid pressure of the wheel cylinder WC is small).

[Basic Control of Brake Force Holding Device]
Vehicle brake force retention device RU according to the first embodiment
The basic control of the (control unit CU) will be described. 1) The brake force holding device RU continues to apply the braking force to the vehicle even after the brake operation is released until a start driving force is generated in the vehicle itself. The condition “even after the brake operation is released” is that the braking force is reduced by the driver releasing the brake operation. Therefore,
This is because if the braking force is not continuously applied to the vehicle, the vehicle will retreat on an uphill. The condition "until the starting driving force is generated" is that when the starting driving force is not generated, the solenoid valve SV is shut off (including the regulated pressure state), and if no braking force is applied, retreating on an uphill is required. Because it occurs. Note that “until the start driving force is generated” will be described later as creep rising.

2) The braking force holding unit RU is
The brake operation amount of the driver is detected, and the operation is performed based on the brake operation release speed. Specifically, the operation is performed on condition that the brake release speed exceeds a threshold. The reason why the “threshold value” is set as a condition is that, as described above, a brake operation that is not intended to release the driver's depression of the brake pedal BP is cut as noise.
This is because, when the brake operation release speed is low, such as on a downhill, the operation of the brake force holding device RU is prohibited, and the slow forward movement is smoothly performed by loosening the depression of the brake pedal BP. That is, if the braking force is held during the slow forward movement on the downhill, it becomes difficult to control the vehicle according to the driver's will.

3) The braking force holding unit RU is
The pressure of the solenoid valve SV in the shut-off state is immediately adjusted. The “pressure adjustment state” is achieved by gradually reducing the brake force (gradual decrease).
By doing so, the driving force and the braking force, which are rising, are harmonized with each other, and a smooth start of the vehicle is achieved.
In addition, this is because a driver who intends to move forward at a very low speed can be operated by loosening the depression of the brake pedal BP on a downhill.

By performing such control, it is possible to realize a start without retreating on an uphill slope and a very slow forward movement due to its own weight on a downhill slope. In addition, even if the braking force holding device operates and holds (acts) the braking force on a flat ground or a gentle downhill, the braking force is gradually reduced and gradually decreased. In addition, when a start driving force is generated in the vehicle, the holding of the braking force is released. Therefore, the operation of the driver is not hindered.

{Specific Control of Vehicle} Next, what kind of control is performed in the vehicle of the first embodiment will be specifically described (see FIGS. 3 to 9). Here, FIG.
Is a control logic for holding the braking force of the braking force holding device. 4A and 4B show control logic for setting a weak creep state, control logic for setting a strong creep state during running, and control logic for setting a middle creep state during driving. FIG. 5 shows control logic for automatically stopping the engine of the prime mover stopping device. FIG.
(A) of the braking force holding device is a control logic (first decreasing speed → second decreasing speed → communication state) for releasing the holding of the braking force due to the generation of the starting drive force in the vehicle itself.
(B) is a control logic for releasing the holding of the braking force from the viewpoint of fail-safe and the like (first decreasing speed → communication state), and (c) is a control logic for determining the rise of creep. 7A and 7B show control logic (vehicle reversal detection version) for setting a strong creep state and control logic (vehicle movement detection version) for setting a strong creep state. 8A and 8B show control logic for automatically starting the engine (vehicle reversal detection version) and control logic for automatically starting the engine (vehicle movement detection version). 9A and 9B show an example of a vehicle backward detection method, in which FIG. 9A is a configuration diagram of vehicle backward detection, FIG. 9B is a pulse phase of the directional rotation shown in FIG. 9A, and FIG. Is the pulse phase.

[Case where Brake Force is Held] The case where the brake force is held by the brake force holding device RU (the case where the brake force is applied) will be described. The braking force is maintained when all of the following four conditions are satisfied (see FIG. 3). I) The brake switch BSW is ON. II) The position switch PSW is not any of neutral (N range), parking (P range), and reverse (R range). III) The vehicle speed is 0 km / h. VI ) The brake release speed exceeds a threshold value (predetermined value) When all of these conditions are satisfied, the control current CU is supplied from the control unit CU to the solenoid valve SV at a predetermined current value, and the solenoid valve SV is shut off. And the braking force is maintained. The control unit CU gradually reduces the current value of the control current I of the solenoid valve SV in the shut-off state immediately at a predetermined first decreasing speed to bring the solenoid valve SV into the pressure regulating state ( Second
Will be described later). Here, the solenoid valve SV
Are set to the cutoff state by the control unit CU of the CVT ECU 6.
To judge. Further, the current value of the control current I for turning off the solenoid valve SV of the control current I, the first decreasing speed at which the current value is gradually reduced, and the like follow the table provided in the control unit CU.

The conditions for maintaining the above-mentioned braking force will be described individually. I) The condition that "the brake switch BSW is ON" is because when the brake switch BSW is OFF, there is no or very little braking force to be held in the wheel cylinder WC.

II) The condition that the position switch PSW is not in any of the neutral (N range), parking (P range) and reverse (R range) conditions is that the brake force holding device R is in the N range and the P range.
This is because the strong creep state is maintained in the R range in order to eliminate useless movement of the U, so that the vehicle is prevented from moving backward by the driving force in the strong creep state. Therefore, the braking force is maintained in the D range (drive range) and the L range (low range).

IV) The condition "vehicle speed is 0 km / h" is because the vehicle cannot be stopped at an arbitrary position if the solenoid valve SV is shut off during traveling. On the other hand, if the vehicle speed is 0 km / h, the vehicle is in a stopped state, so that there is no problem in driving operation even if the braking force is maintained. Note that “vehicle speed is 0 km / h” includes a state where the vehicle is slightly moving.

V) The condition (F_BKTH = 1) that "the brake release speed exceeds the threshold value" is an operation for releasing the driver's depression of the brake pedal when the brake release speed exceeds the threshold value. Because the intention to launch is clearly recognized. In addition, when the brake operation release speed is slow enough not to exceed the threshold value, the vehicle is located on a downhill or the like, and in such a case, the braking force is adjusted so that the driver can perform the brake operation at will. This is because it is appropriate not to activate the control unit RU. Furthermore, it is a wasteful operation to operate the brake force holding device RU to hold the brake force from when the vehicle stops until the driver releases the brake pedal BP. Therefore, the fact that the brake operation release speed exceeds the threshold value is added to the condition for maintaining the braking force. That is, the braking force is held for the first time when the driver releases the brake pedal BP at a brake operation release speed equal to or higher than the threshold.

When the control current I is supplied to the solenoid valve SV, the braking force control unit RU immediately reduces the value of the control current I and attempts to adjust the pressure. However, as described above, when the brake fluid pressure of the wheel cylinder WC is large, the pressure may be maintained after the communication state is maintained for a while. On the other hand, when the brake fluid pressure of the wheel cylinder WC is small, the pressure may be adjusted after the shut-off state is maintained for a while. The case where the holding (operation) of the braking force is released will be described later.

[Conditions for Issuing Weak Creep Command] The vehicle of the present embodiment reduces fuel consumption when the vehicle is stopped.
In order to suppress the occurrence of vehicle body vibration by controlling the driving force in the strong creep state with the braking force,
The driving force is set to a weak creep state under predetermined conditions. Hereinafter, conditions under which the weak creep command is issued will be described. The condition for issuing the weak creep command (F_WCRP) is when the following condition I) or II) is satisfied (FIG. 4).
(A)). I) The position switch PSW is in the N range or the P range. II) The following conditions are satisfied.
W is in the forward (DL) range, and 4) the vehicle speed is 5 km / h or less. 5) The vehicle speed> 5 km / h and the vehicle speed> 4 km / h after transition to the strong creep state, or 6) the weak creep state, or 7) the vehicle speed 0
km / h, medium creep state, and predetermined time after transition to medium creep state

When either condition I) or II) is satisfied, a weak creep command is issued and the vehicle enters a weak creep state. The above conditions are determined by the driving force control unit DCU.

The conditions under which the above-described weak creep command is issued will be described individually. I) The condition that the position switch PSW is in the N range or the P range is that the accelerator pedal is quickly depressed at the same time as switching from the non-travel range (NP range) to the travel range (DL, R range). In this case, the driving force transmission capacity of the starting clutch is quickly increased, and the vehicle can be started smoothly. That is, in the weak creep state, the hydraulic chamber of the starting clutch is already filled with the pressure oil, and there is no invalid stroke (play) of the pressing piston. Therefore, when the value of the pressure oil is increased, the driving force transmission capacity increases quickly. It should be noted that even though the weak creep state is set in the NP range, this is because the driving force transmission capacity of the starting clutch is set to the capacity in the weak creep state in advance. Not necessarily. In this point, it is different from the weak creep state in the D / L range. Incidentally, in the NP range, the connection between the engine 1 and the drive wheels 8 is completely cut off by a forward / reverse switching mechanism arranged in series with the starting clutch on the driving force transmission path. That is, in the NP range, neither the forward driving force transmission path nor the reverse driving force transmission path is set.
Therefore, no driving force is transmitted from the engine 1 to the driving wheels 8 at all.

The condition II) is a basic condition for the conditions 1) to 4) to be in the weak creep state, and the conditions before the weak creep state are the conditions 5) to 7) Either state is a condition for the weak creep state.

1) The condition "the brake force holding device RU is normal" is that if the brake force holding device RU is abnormal, the brake force cannot be held after the driver releases the brake operation.
This is because if the braking force is not maintained, the vehicle cannot move backward on a slope in a weak creep state. For example, if there is an abnormality such as the solenoid valve SV not being in the shut-off position, and a weak creep command is issued and the vehicle is in a weak creep state, the brake fluid pressure is not held in the wheel cylinder WC after the brake pedal BP is released (braking force). Is not retained). Therefore, when the driver cancels the depression of the brake pedal BP at the time of starting on the slope, the braking force is lost at once, and the vehicle retreats on the slope. In this case, maintaining a strong creep condition prevents retreat on a slope and starts on a slope (starts on a slope).
To facilitate.

2) The condition that the "brake switch BSW is ON" is because the driver does not want to at least reduce the driving force when the brake pedal BP is not depressed.

3) The condition that the position switch PSW is in the forward (D · L) range is for improving fuel efficiency in the forward range. In the D range, a weak creep state is set in both the D mode and the S mode. By the way, in the R range, the vehicle is not switched to the weak creep state in order to facilitate the garage due to the strong creep traveling.

4) When the vehicle speed is 5 km / h or less, the reverse driving force from the driving wheels 8 is transmitted to the engine 1 and the motor 2 via the starting clutch of the CVT 3 at a vehicle speed exceeding 5 km / h. This is because the engine brake may be activated or regenerative power generation by the motor 2 may be performed.

5) “Vehicle speed after transition to strong creep state> 5 km
/ H and vehicle speed> 4 km / h "is because the weak creep state can be obtained only by deceleration by depressing the continuous brake. Since the driving force difference between the strong creep state and the weak creep state is large, if the vehicle is switched from the strong creep state to the weak creep state when the brake pedal BP is depressed, the strong unintentional state of the driver before the vehicle stops. Produces a sense of deceleration. In addition, when the vehicle is stopped and on an uphill, instantaneous retreat may occur. Therefore, it is necessary to prevent switching from the strong creep state to the weak creep state. Therefore, when the vehicle enters a strong creep condition, the vehicle speed exceeds 5 km / h and the throttle is turned off.
Do not switch to the weak creep state until the accelerator pedal is released and the vehicle switches to the strong creep state during running. After a strong creep condition, the vehicle speed is 5km
/ H when the driving force decreases (strong creep state during running), for example, when the vehicle is approaching an uphill, even if the brake pedal BP is not depressed, the vehicle speed is again 5 km.
/ H. At this time, since the brake switch BSW is OFF, the vehicle enters a strong creep state when the vehicle speed decreases to 5 km / h. Even in such a case, in order to prevent the switching from the strong creep state to the weak creep state from being performed thereafter, the vehicle speed is greater than 4 km /
The condition of h is provided, and if the brake pedal BP is not depressed when the vehicle speed falls again to 5 km / h, then the switching to the weak creep state is not executed. If the brake pedal BP is depressed when the vehicle speed decreases to 5 km / h (the brake switch BSW is turned on), switching from the strong creep state during running to the weak creep state is executed. That is, when the vehicle speed is reduced to 5 km / h again (vehicle speed = 5 km / h), if the opportunity to enter the weak creep state is missed, the strong creep state is maintained as long as the vehicle speed is 5 km / h or less.

6) The condition of "weak creep state" is because once in the weak creep state, the conditions of 5) and 7) are excluded to maintain the weak creep state. The condition 5) is set to a weak creep state when the vehicle reaches 5 km / h, but the condition is not satisfied when the vehicle becomes smaller than 5 km / h. Therefore, if the vehicle speed is lower than 5 km / h, the weak creep state cannot be maintained only under the condition 5). Therefore, in order to maintain the weak creep state even when the vehicle speed becomes less than 5 km / h, the weak creep state is a condition.

7) The condition that the vehicle speed is 0 km / h, the medium creep state, and a predetermined time has elapsed after the transition to the medium creep state is to prevent deterioration of fuel consumption and deterioration of vehicle body vibration when the vehicle is stopped in the strong creep state. by. When the vehicle speed drops again to 5 km / h (vehicle speed = 5 km / h
h) to miss the opportunity to switch to a weak creep condition (5
Or if the vehicle speed is maintained at 5 km / h or less after the depression of the brake pedal BP is released after the vehicle enters the weak creep state and the vehicle enters the strong creep state, the strong creep state is maintained. Further, if the vehicle stops in a strong creep state while the brake pedal BP is depressed, fuel efficiency deteriorates and vehicle body vibration continues. Therefore, the vehicle is completely stopped (vehicle speed = 0 km / h), enters a medium creep state in which the driving force is intermediate between the strong creep state and the weak creep state, and furthermore, a predetermined time ( In this embodiment, if 300 msec has elapsed, the state is switched to the weak creep state. As described above, since the braking force is increased by depressing the brake pedal BP while the driving force is gradually lowered from the strong creep state to the medium creep state, and further to the weak creep state, an instant retreat on an uphill is also possible. It can be kept as small as possible.

[Conditions for Issuing Strong Creep During Running] Conditions for issuing a strong creep during running will be described. The strong creep command during running (F_MSCRP) is issued when both of the following conditions I) and II) are satisfied (see FIG. 4B). After a strong creep command during running, the vehicle enters a strong creep condition during running. I) The vehicle speed is greater than 5 km / h. II) The throttle is OFF (the depression of the accelerator pedal is released). These conditions are determined by the driving force control unit DCU. In addition, the driving force is set to a strong creep state during running,
This is because a strong sense of deceleration given to the driver before the vehicle stops, which occurs when the vehicle is switched from the strong creep state to the weak creep state, is not generated. For this reason, the driving force is set to be smaller than the driving force in the strong creep state before entering the weak creep state.

The conditions under which the strong creep command during running is issued will be described individually. I) The condition that “vehicle speed> 5 km / h” means that when the vehicle shifts from the strong creep state to the weak creep state, the vehicle speed once exceeds 5 km / h after the transition to the strong creep state, and then the vehicle speed becomes 5 km / h. The reason is that the creep condition is set at the point when the creep is reached. Further, this is for discriminating between a strong creep state in which the vehicle speed is 5 km / h or less and a strong creep state in running when the vehicle speed exceeds 5 km / h.

II) "Throttle is OFF (T
H OFF) "is because the driver does not want to increase the driving force and there is no problem even if the driving force is reduced.

[Conditions for Issuing Medium Creep Command] The conditions for issuing the medium creep command will be described. The condition for issuing the medium creep command (F_MCRP) is when all three of the following conditions I), II) and III) are satisfied (see FIG. 4C). I) The brake switch BSW is ON. II) The position switch PSW is in the forward (DL) range. III) The vehicle is completely stopped (vehicle speed = 0 km / h). It is determined by the control unit DCU. The driving force is changed to the medium creep state when the vehicle speed decreases again to 5 km / h (vehicle speed = 5 km / h).
If the vehicle loses the opportunity to switch to the weak creep state, or if the vehicle speed is maintained at 5 km / h or less after the depression of the brake pedal BP is released after the weak creep state is reached and the strong creep state is maintained, the strong creep The state is maintained. Furthermore, if the vehicle stops in a strong creep condition,
Fuel economy has deteriorated and body vibration has continued. Therefore, if the vehicle is switched from the strong creep state to the weak creep state when the vehicle is stopped, instantaneous retreat occurs as described above. Therefore, the vehicle is switched to the medium creep state which is a driving force intermediate between the strong creep state and the weak creep state.

The conditions under which the above-mentioned medium creep command is issued will be described individually. I) The condition that the "brake switch BSW is ON"
When the brake pedal BP is not depressed, it is because the driver does not want to at least reduce the driving force.

II) The condition that the position switch PSW is in the forward (D · L) range is a weak creep state in the D range or the L range. Because it is caused. In the NP range, the transmission is switched to the weak creep state at the same time as the transmission is switched, so that there is no need to set the medium creep state. Further, in the R range, there is no need to set the medium creep state to maintain the strong creep state.

III) "Complete stop of vehicle (ie, vehicle speed =
0 km / h) because the weak creep state is set in order to suppress the deterioration of fuel efficiency and the body vibration in the strong creep state when the vehicle is stopped, so that the intermediate creep state is required as a transient state. For that reason.

Whether the vehicle is in the weak creep state, the strong creep state during running, or the middle creep state is determined based on the hydraulic pressure command value for the starting clutch of the CVT 3.

[Automatic engine stop condition] In order to further improve fuel efficiency, the engine 1 is automatically stopped when the vehicle is stopped. This condition will be described. When all the conditions shown in FIG. 5 are satisfied, an engine stop command (F_ENG
OFF) is issued, and the engine 1 automatically stops.
The automatic stop of the engine 1 is performed by a motor stop device.
Therefore, the following engine automatic stop condition is determined by the motor stop device. Note that the condition for automatically stopping the engine 1 is determined by the FI / MG ECU 4 and the CVT ECU 6.
When all of the conditions I) to VIII) are satisfied as determined by the I / MG ECU 4, F_MGSTB becomes 1, and CVTE
When all of the conditions IX) to XV) are determined by CU6, F_CVTOK becomes 1.

The conditions for automatically stopping the engine will be described individually. I) The condition "the brake switch BSW is ON" is for the purpose of calling attention to the driver.
When the brake switch BSW is ON, the driver has put his foot on the brake pedal BP. Therefore,
This is because even if the driving force is lost due to the automatic stop of the engine 1 and the vehicle starts to retreat on a slope, the driver can easily increase the brake pedal BP.

II) The condition that “the water temperature of the engine 1 is equal to or higher than a predetermined value” is because the automatic stop / auto start of the engine 1 is preferably performed while the engine 1 is stable. . If the water temperature is low, the engine 1 may not restart in a cold region.

III) "After starting the engine 1, once the vehicle speed becomes 5
km / h or more "is for the purpose of facilitating garage out and garage entry during creep running. This is because it is troublesome if the engine 1 is automatically stopped every time the vehicle is stopped due to a switching operation when the vehicle is taken in and out of the garage.

IV) "Position switch PSW and mode switch MSW are in a range other than RD (S mode) and L range (that is, ND (D mode)
The condition “P range)” is based on the following reason. If the position switch PSW is in the R range, it is troublesome if the engine 1 automatically stops frequently when entering the garage or the like. This is because when the position switch PSW is in the D range and the mode switch MSW is in the S mode, or when the position switch PSW is in the L range, the driver expects that the vehicle can be started quickly.

V) The condition that “the battery capacity is equal to or more than a predetermined value” is for the purpose of preventing a situation where the engine 2 cannot be restarted by the motor 2 after the engine 1 is stopped.

VI) The condition of "not more than the predetermined value of the electric load" is for the purpose of ensuring the supply of electricity to the load.

VII) The condition that “the negative pressure of the master power MP in the constant pressure chamber is equal to or more than a predetermined value” means that if the negative pressure of the master power MP in the constant pressure chamber is small, the depression force when the brake pedal BP is depressed. This is because the amplification of the vehicle becomes small and the effectiveness of the brake decreases (it is not assisted). That is, when the engine 1 is stopped in a state where the negative pressure in the constant pressure chamber is small, the negative pressure in the constant pressure chamber becomes
, The negative pressure in the constant-pressure chamber is further reduced. Therefore, the amplification of the depression force when the brake pedal BP is depressed is reduced, and the effectiveness of the brake is reduced.

VIII) The condition that the accelerator pedal is not depressed (TH OFF) is because the driver does not want to increase the driving force and there is no problem even if the engine 1 is stopped. .

IX) "Engine 1 in FI / MG ECU 4"
That the automatic stop condition of the engine 1 is satisfied and all the automatic stop conditions of the engine 1 are completed. " Because it is not.

X) The condition "vehicle speed is 0 km / h" is because there is no problem even if the driving force is lost if the vehicle is stopped.

XI) The condition "the ratio of CVT3 is low" is because if the ratio (pulley ratio) of CVT3 is not low, it may not be possible to start smoothly.

XII) The condition that “the oil temperature of the CVT 3 is equal to or higher than a predetermined value” is satisfied when the oil temperature of the CVT 3 is low.
The actual hydraulic pressure rise of the starting clutch is delayed,
This is because it takes time from the start of the engine 1 to the strong creep state, and the vehicle may retreat on a slope.

XIII) The condition that the accelerator pedal is not depressed (TH OFF) is because the driver does not want to increase the driving force and there is no problem even if the engine 1 is stopped. .

XIV) The condition "the brake force holding device RU is normal" means that if the brake force holding device RU is abnormal, the brake force is reduced when the driver releases the brake pedal BP. This is because it may not be possible to hold the vehicle, so that a strong creep condition is maintained so that the vehicle does not retreat on a slope.

XV) "(1) Brake switch BSW is set to O
N] or [2) the position switch PSW is in the NP range] for the following reason. 1) When the brake switch BSW is ON, the braking force is maintained, so that even when the engine 1 automatically stops and the driving force is lost, the vehicle does not retreat on an uphill.
In addition, the driver has put his foot on the brake pedal BP. Therefore, even if the driving force is lost due to the automatic stop of the engine 1 and the vehicle starts to retreat on a slope, the driver can easily increase the brake pedal BP. 2) When the vehicle is stopped with the position switch PSW in the P range or the N range, the driver does not intend to stop the engine 1 because the driver intends to completely stop the vehicle.

[Case where Holding of Brake Force is Canceled] Next, a case where the holding (operation) of the brake force is canceled by the brake force holding device RU will be described. It should be noted that the release of the holding of the braking force is released when a start driving force is generated in the vehicle itself (under the condition of FIG. 6A).
In some cases (the condition of FIG. 6B).

The holding of the braking force due to the generation of the starting drive force in the vehicle itself is released when the following condition is satisfied (see FIG. 6A). I) Creep rising and brake operation release speed being equal to or higher than a threshold value When this condition is satisfied, the control unit CU sets the solenoid valve SV in the pressure regulating state at the first reduced speed.
The current value of the control current I to be supplied to the motor is reduced at the second decreasing speed until the communication state is established, and the holding of the brake fluid pressure is released.

I) "Creep rise (F_SCDL)
Y = 1) and the brake release speed is equal to or higher than the threshold value (F_BKTH = 1) "is a process in which the driving force increases to the strong creep state, and the vehicle has not reached the strong creep state. Considering the inertia force and rolling resistance (plus the driving force in the increasing process), it is possible to suppress the retreat on uphill slopes and to realize the abrupt start of the vehicle on downhill slopes. by. In the first and second decreasing speeds for decreasing the current value of the control current I, the decreasing rate is set to be larger in the second decreasing speed, and the braking force is reduced quickly, so that unnecessary brake dragging is performed. It does not happen. This second
The decrement speed follows the table provided in the control unit CU similarly to the first decrement speed.

On the other hand, the release of the holding of the braking force from the viewpoint of fail-and-safe or the like is performed when any of the following conditions is satisfied (see FIG. 6B). I) The position switch PSW is in the NP range and the brake switch BSW is OFF. II) The vehicle speed has exceeded 20 km / h. When any of these conditions is satisfied, the control unit C
U immediately reduces the current value of the control current I supplied to the solenoid valve SV in the pressure decreasing state at the first decreasing speed to zero (substantially zero), and switches the solenoid valve SV in the pressure regulating state to the direct communication state. Release the brake force at once.

Solenoid valve S in pressure regulation state at first decreasing speed
Conditions for switching the V to the direct communication state and releasing the holding of the braking force will be individually described. I) The condition that "the position switch PSW is in the NP range and the brake switch BSW is OFF" is for the purpose of eliminating useless operation of the braking force holding device RU.

II) "The vehicle speed exceeds 20 km / h"
This condition is for the purpose of eliminating unnecessary brake dragging as a fail-and-safe action.

[Determining Conditions for Creep Rising] The conditions for determining creep rising will be described. It is determined that creep has risen when either of the following I) or II) is satisfied (see FIG. 6C). I) The hydraulic pressure command value of the starting clutch of the CVT 3 is equal to or more than a predetermined value. II) The engine 1 is restarted after the automatic stop and a predetermined time has elapsed. These two conditions are determined by the driving force control unit DCU. . When the creep rises, the brake force holding device R
Even when the operation of U is released and the braking force is lost, the driving force is increased to such an extent that the retreat on an uphill can be suppressed in consideration of the inertia force and the rolling resistance (plus the driving force in the increasing process) of the vehicle. It is in the state of doing. Further, the creep rising includes a state where the driving force is increased to such an extent that the retreat can be suppressed to a minimum by the increased driving force even if the vehicle slightly retreats.

The conditions for judging the rise of the creep will be described individually. I) The condition that “the hydraulic command value of the starting clutch of the CVT 3 is equal to or more than a predetermined value” is the above-mentioned reason even if the holding of the braking force is released if the hydraulic command value of the starting clutch of the CVT 3 is equal to or more than the predetermined value. This is because it is determined that the driving force has increased to such an extent that the vehicle can be prevented from retreating on an uphill. Another reason is that a smooth start without a sudden feeling can be performed even on a downhill. Note that when the hydraulic command value of the starting clutch is equal to or more than the predetermined value, the hydraulic command value to the linear solenoid valve that controls the hydraulic pressure of the engaging force of the starting clutch during the process of shifting from the weak creep state to the strong creep state is in the weak creep state. This is the point in time when the value has increased to a value approximately in the middle of the high creep state.

II) The condition that "the engine 1 has been restarted after the automatic stop and a predetermined time has elapsed" means that if the engine 1 is restarted after the automatic stop and the predetermined time has passed, the above-mentioned condition is maintained even if the holding of the braking force is released. This is because it is determined that the driving force has increased to such an extent that the vehicle can be prevented from retreating on an uphill. Another reason is that a smooth start without a sudden feeling can be performed on a downhill. The predetermined time is counted from the time when the engine 1 is actually restarted and the supply of the pressure oil to the starting clutch of the CVT 3 is started. This is because when the engine 1 is stopped, the hydraulic oil in the hydraulic chamber of the starting clutch of the CVT 3 is leaked, and when the engine 1 is started and the supply of the pressure oil is started, the invalid stroke (play) of the pressing piston is caused. There is. Therefore, the hydraulic pressure command value to the linear solenoid valve of the starting clutch does not match the actual hydraulic pressure value (driving force transmission capacity). As a result, when the driving force increases from the stop state of the engine 1, it is not possible to determine the creep start from the hydraulic command value of the starting clutch of the CVT 3. Therefore, when shifting from the stopped state of the engine 1 to the strong creep state, the timer starts counting from the time when the supply of the pressure oil to the starting clutch is started, and the creep rising is determined.

[Conditions for Issuing Strong Creep Command] Conditions for issuing a strong creep command will be described. The strong creep command (F_SCRP) is shown in FIG. 7 (a) or FIG. 7 (b).
It is emitted when the condition shown in is satisfied, and it becomes a strong creep state. The first condition for issuing a strong creep command is when either of the following I) or II) is satisfied (FIG. 7).
(A)). I) [1) Brake switch is OFF or throttle is O
N and the position switch PSW is in the forward (DL) range] or [2] The position switch PSW is in the reverse (R)
Range], and 3) The vehicle speed is 5 km / h or less. II) The vehicle retreat is detected.

Alternatively, the second case in which a strong creep command is issued
The condition is that either of the following III) or IV) is satisfied (see FIG. 7B). III) [1] Brake switch is OFF or throttle is ON, and position switch PSW is forward (DL).
Range] or [2) Position switch PSW is in reverse (R) range], and 3) Vehicle speed is 5 km / h or less. IV) Vehicle speed pulse is input and vehicle is completely stopped before vehicle speed pulse is input.

Incidentally, the first condition and the second condition under which the strong creep command is issued are the same as the conditions I) and III), but different from the conditions II) and IV). Therefore,
Description of the condition III) that is the same as the condition I) is omitted. These conditions are determined by the driving force control unit DCU.

The conditions under which the above-mentioned strong creep command is issued will be described individually. First, the conditions 1) to 3) of I) will be described. Since the contents are the same as those of III), the description of III) is omitted. 1) "Brake switch is off or throttle is on
And the position switch PSW is in the forward (D · L) range ”, because the driver has shifted to the starting operation and thus shifts to the strong creep state. That is, since the driver sets the position switch PSW to the D range or the L range and releases the depression of the brake pedal BP or depresses the accelerator pedal, the driver intends to start. Therefore, the state is switched from the weak creep state to the strong creep state. When the accelerator pedal is depressed, the driving force transmission capacity after the driving force transmission capacity reaches a large state increases to a capacity that can transmit all of the driving force generated by the prime mover (a state larger than the large state). Is done. However, the flag is a strong creep flag (F_SCRPO) until another flag is set next time.
N) continues to stand. By the way, "Brake switch is O
It is more preferable that the condition that the brake release speed exceeds the threshold (F_BKTH = 1) be used instead of the condition "FF". That is, the braking force holding device RU of the vehicle according to the present embodiment holds the braking force on condition that the brake operation release speed exceeds the threshold value. Therefore,
This is because, in some situations, the braking force may be significantly reduced before the brake release speed reaches the threshold value. On the other hand, if the vehicle enters the strong creep state at a small brake operation release speed less than the threshold value, the vehicle enters a strong creep state with a slight brake operation that is not intended for the driver to start, causing vehicle body vibration by controlling the driving force with the braking force This is because there are times.

2) The condition that the position switch PSW is in the reverse (R) range is because the creep running in the R range is smoothly performed. That is, when the driver switches the position switch PSW to the R range, the driver may want to enter the garage or the like by traveling with the driving force in the strong creep state. Therefore, the state is switched from the weak creep state to the strong creep state.

3) The condition that the vehicle speed is 5 km / h or less is for the purpose of judging the strong creep condition during running when the vehicle speed exceeds 5 km / h and the strong creep condition when the vehicle speed is 5 km / h or less. .

II) The condition of "vehicle retreat detection" is such that, on a steep ascending slope, the vehicle starts moving backward due to the moving force due to the vehicle's own weight exceeding the braking force. For that reason. In the case of an uphill, the sum of the driving force in the weak creep state (the driving force is zero when the engine 1 is stopped) and the braking force is the braking force against the moving force due to the vehicle's own weight.
However, as the slope becomes steeper, the moving force of the vehicle due to its own weight increases. Therefore, on a steep ascending slope, the moving force of the vehicle due to its own weight exceeds the sum of the driving force and the braking force in the weak creep state, and the vehicle moves backward. Therefore, when the vehicle is detected to move backward, the vehicle is unconditionally changed from the weak creep state to the strong creep state to generate a driving force against an uphill.

Here, the means for detecting the backward movement of the vehicle will be described with reference to FIG. For example, the helical gears HG (A), HG are located downstream of the starting clutch of CVT3.
(B) is provided. The helical gears HG (A), HG
The position where (B) is provided should just be a position which rotates with a tire. As shown in FIG. 9A, the helical gear HG
(A) and HG (B) have spiral teeth and are obliquely cut in the circumferential direction. Therefore, the phase of the tooth is shifted depending on the direction of the tooth or the rotational direction of the direction. Therefore,
Electromagnetic pickups P (A) and P (B) are provided on the same axis AX of the helical gears HG (A) and HG (B), and the tip of the tooth is detected by the electromagnetic pickups P (A) and P (B). . Then, the electromagnetic pickups P (A) and P (B)
The rotational direction is determined from the position of the pulse phase difference on the basis of the two pulses detected in (1). By the way, when rotating in the direction, as shown in FIG. 9B, the pulse detected by the electromagnetic pickup P (B) is
The pulse is shifted backward from the pulse detected in (A). That is, the tips of the teeth of the helical gear HG (A) are detected earlier than the tips of the teeth of the helical gear HG (B). On the other hand,
When rotating in the direction, as shown in FIG. 9C, the detected pulse detected by the electromagnetic pickup P (B) shifts ahead of the pulse detected by the electromagnetic pickup P (A).
That is, the tips of the teeth of the helical gear HG (A) are detected after the tips of the teeth of the helical gear HG (B). Thus, the rotation direction can be detected from the position of the pulse phase difference. Therefore, for example, in the case where the rotation in the direction is the backward movement of the vehicle, if the pulse detected by the electromagnetic pickup P (B) is shifted backward from the pulse detected by the electromagnetic pickup P (A), it is determined that the vehicle is moving backward. Although the helical gears HG (A) and HG (B) are used, any gear may be used as long as there is a phase difference between the teeth of the two gears.

IV) The condition that "the vehicle is completely stopped before the vehicle speed pulse is input and the vehicle speed pulse is input" is that if the vehicle moves even a little from the completely stopped state, the vehicle may retreat (retreat). There is a reason) to make a strong creep state and to resist the slope. That is, it is not determined whether the vehicle has moved forward or backward, but the time when the vehicle has moved is determined. In the case of a slope, the sum of the driving force of weak creep (the driving force is zero when the engine 1 is stopped) and the braking force is the braking force against the moving force due to the vehicle's own weight. However, as the slope becomes steeper, the moving force due to its own weight increases. Therefore, on a steep hill, the moving force of the vehicle due to its own weight exceeds the sum of the driving force and the braking force of the weak creep, and the vehicle may move forward (downhill) or retreat (uphill). Then, the forward or backward movement of the vehicle (that is, the movement of the vehicle) is detected, the weak creep state is changed to the strong creep state, and the driving force against the slope is generated. First, before the vehicle speed pulse is input, it detects that the vehicle speed pulse is 0 pulse, and detects that the vehicle is completely stopped. Thereafter, when even one pulse of the vehicle speed is input, it is determined that the vehicle has moved. It should be noted that even when the vehicle travels in the direction intended by the driver, bringing the driving force into the strong creep state does not hinder the driver's will, so there is no problem.

[Automatic Engine Start Condition] The conditions for automatically starting the engine 1 after the automatic stop of the engine 1 will be described. When the conditions shown in FIG. 8A or 8B are satisfied, an engine start command (F_ENGON) is issued, and the engine 1 starts automatically. The automatic start of the engine 1 is performed by a motor stop device. Therefore,
The following automatic engine start conditions are determined by the motor stop device. The automatic start condition of the engine 1 is FI / MG
Determined by ECU 4 and CVT ECU 6, FI / MGEC
When one of the conditions I) to VI) is satisfied as determined by U4, F_MGSTB becomes 0, and as determined by the CVT ECU 6, VII) to XI) [or VII) to X) and XII)].
F_CVTOK becomes 0 when any one of the conditions is satisfied. Incidentally, the first condition (the condition shown in FIG. 8 (a)) and the second condition (the condition shown in FIG.
(Conditions shown in (b)) are determined by CVT ECU 6 XI)
Vehicle reversal detection and XII) Only the conditions for the vehicle to stop completely before the vehicle speed pulse is input and the vehicle speed pulse is input are different. Therefore, the second condition at which the automatic start condition of the engine 1 is issued
Only the conditions will be described.

I) "The depressing of the brake pedal BP is released (that is, the brake switch BSW is
FF) "is because it is determined that the driver's start operation has been started by releasing the brake pedal. That is, in the case of the D range D mode, the driver releases the depression of the brake pedal BP when the start operation is started, so that the engine 1 is automatically started. In the case of the P range and the N range, the driver releases the depression of the brake pedal BP in order to get out of the vehicle or the like. At this time, it is necessary for the driver to turn off the ignition switch by automatically stopping the engine 1. The engine 1 is automatically started so as not to leave the vehicle on the assumption that there is nothing. In addition,
Similar to the condition for issuing the strong creep command, it is more preferable to automatically start the engine on condition that the brake release speed exceeds the threshold (F_BKTH = 1). As described above, in the case of the vehicle according to the present embodiment, the braking force may be considerably reduced before the brake release speed reaches the threshold. On the other hand, if the engine is automatically started at a small brake operation release speed less than the threshold value, the engine is automatically started by a slight brake operation not intended for the driver to start.

II) The condition that the position switch PSW and the mode switch MSW have been switched to the RD (S mode) and L ranges is that after the engine 1 is automatically stopped, the position switch PSW and the mode switch M
The fact that the SW is switched to one of the R, D (S mode) and L ranges is because the driver is determined to have an intention to start immediately. Therefore, after the engine 1 is automatically stopped in a range other than the RD (S mode) / L range, when the engine 1 is switched to the RD (S mode) / L range, the engine 1 is automatically started.

III) The condition that "the battery capacity is equal to or less than the predetermined value" is for the purpose of preventing the engine 1 from automatically starting when the battery capacity is reduced. That is, unless the battery capacity is equal to or greater than the predetermined value, the engine 1 is not automatically stopped. However, even after the engine 1 is automatically stopped, the battery capacity may be reduced. In this case, the engine 1 is automatically started for the purpose of charging the battery. Note that the predetermined value is set to a value higher than the limit battery capacity at which the engine 1 cannot be automatically started when the battery capacity is further reduced.

IV) "Electric load is not less than a predetermined value"
This is because, for example, when an electric load such as lighting is operating, the battery capacity is rapidly reduced, and the engine 1 cannot be restarted. Therefore, when the electric load is equal to or more than the predetermined value regardless of the battery capacity, the engine 1 is automatically started.

V) The condition that the negative pressure of the master power MP is equal to or less than a predetermined value is because the braking force of the brake decreases as the negative pressure of the master power MP decreases. Therefore, when the negative pressure of the master power MP falls below a predetermined value, the engine 1 is automatically started.

VI) The condition that the accelerator pedal is depressed (TH ON) is because the driver expects the driving force of the engine 1.
Therefore, when the accelerator pedal is depressed, the engine 1 is automatically started.

VII) The condition that “the conditions for automatically starting the engine 1 in the FI / MG ECU 4 are satisfied” is as follows.
This is because the automatic start condition of the engine 1 determined by the FI / MG ECU 4 is also determined by the CVT ECU 6.

VIII) The condition that the accelerator pedal is depressed (TH ON) is because the driver expects the driving force of the engine 1. Therefore, when the accelerator pedal is depressed, the engine 1 is automatically started.

IX) "The brake pedal BP has been released (that is, the brake switch BSW has been released).
Is OFF) ”because it is determined that the driver's start operation has been started by depressing the brake pedal BP. That is, in the case of the D range D mode, the driver releases the depression of the brake pedal BP when the start operation is started, so that the engine 1 is automatically started. As described above, the brake operation release speed exceeds the threshold (F_B
It is more preferable to automatically start the engine under the condition of KTH = 1).

X) The condition that "the brake force holding device RU is out of order" is that if the brake force holding device RU does not hold the braking force due to the failure, the engine 1 will retreat (forward) on a slope when the engine 1 stops. It is because it is. Therefore, when the solenoid valve SV or the like has failed, the engine 1 is automatically started to create a strong creep state. If a failure is detected in the braking force holding unit RU after the automatic stop of the engine 1, it may not be possible to hold the braking force when the brake pedal BP is released when the vehicle starts moving. When a failure is detected, the engine 1 is automatically started in order to set a creep condition. That is, the vehicle is prevented from moving backward in the strong creep state, and the vehicle is easily started on a slope. The failure detection of the brake force holding device RU is performed by the failure detection device DU.

XI) The condition of "vehicle retreat detection" is that the vehicle 1 starts moving backward because the moving force due to the vehicle's own weight exceeds the braking force on a steep uphill slope.
This is because the driving force is used to suppress the backward movement.
In the case of an uphill, when the engine 1 is stopped, the braking force becomes a braking force against the moving force due to the weight of the vehicle. But,
As the slope becomes steeper, the moving force due to its own weight increases. Therefore, on a steep uphill, the moving force of the vehicle due to its own weight exceeds the braking force, and the vehicle may retreat. Therefore, when the vehicle is moved backward, the engine 1 is unconditionally changed from the stopped state to the strong creep state to generate a driving force against an uphill. The method of detecting the backward movement of the vehicle has been described on the condition that the strong creep command is issued, and thus the description thereof is omitted.

XII) The condition that "the vehicle is completely stopped before the vehicle speed pulse is input and the vehicle speed pulse is input" is that if the vehicle moves even a little from the completely stopped state, the vehicle may retreat (retreat). The engine 1 is automatically started and the driving force is used to resist the slope. That is, it is not determined whether the vehicle has moved forward or backward, but the time when the vehicle has moved is determined. In the case of a slope, when the engine 1 is stopped, only the braking force is the braking force against the moving force due to the vehicle's own weight. However, as the slope becomes steeper, the moving force due to its own weight increases. Therefore, on a steep slope, the moving force of the vehicle due to its own weight exceeds the braking force, and the vehicle may move forward (downhill) or retreat (uphill). Therefore, when the vehicle moves forward or backward (that is,
(Movement of the vehicle), and automatically starts the engine 1 (creates a strong creep state) to resist the slope. First, before the vehicle speed pulse is input, it detects that the vehicle speed pulse is 0 pulse, and detects that the vehicle is completely stopped. After that, even if one vehicle speed pulse is input,
It is determined that the vehicle has moved.

<< Control Time Chart >> Next, how the above-described vehicle according to the first embodiment performs control during traveling will be described with reference to FIGS. 10 and 11. FIG. FIG. 10 is a flowchart of the braking force control in the vehicle braking force holding device according to the first embodiment. FIG. 11 is a control time chart of the vehicle according to the first embodiment. In addition, there are two types of vehicles: a case where the vehicle stops on a gentle uphill or a flat ground (solid line portion in FIG. 11) and a case where the vehicle stops on a downhill (dashed line portion in FIG. 11).
The position switch PSW and the mode switch MSW of the vehicle are not changed in the D mode D range.

[Deceleration → Stop] First, when the vehicle is running (by the way, vehicle speed> 5 km / h), when the driver releases the accelerator pedal (that is, when the throttle is turned off), the driving force control unit DCU runs. A strong creep command (F_MSCRP) is issued to bring the vehicle into a strong creep state during running (F_MSCRPON) (see FIGS. 4A and 4B).
Therefore, the driving force is reduced as compared with the strong creep state (F_SCRPON).

Furthermore, when the driver releases the accelerator pedal and depresses the brake pedal BP (when the brake switch BSW is turned on), the braking force increases. Then, when the brake pedal BP is continuously depressed and the vehicle speed becomes 5 km / h, the driving force control unit DCU issues a weak creep command (F_WCRP) to enter a weak creep state (F_WCRPON) (FIG. 4 (a)). ,
(b)). At this time, the driving state changes from the strong creep state to the weak creep state, so that the driver does not feel a strong deceleration feeling.

Then, the vehicle stops and the vehicle speed becomes 0 km / h. The driver continues to depress the brake pedal BP in order to maintain the vehicle stopped. Therefore, the engine automatically stops (see FIG. 5). Here, the brake force control unit RU operates until the brake release speed exceeds the threshold value (F
_BKTH = 1) Since it does not operate, the solenoid valve SV is in a communicating state (see FIG. 3). This state corresponds to S101 in the flowchart of FIG.

[Stop → start; gentle uphill (flat)] Next, in order to start the vehicle from a gentle uphill or flat (see the solid line in FIG. 11), the driver operates the brake to operate the brake pedal BP. Start releasing the foot (Fig. 11
(a)). Then, the braking force starts to decrease (FIG. 11
(d)). At this time, since the solenoid valve SV is not in either the pressure regulation state or the shutoff state (S102), the brake force control unit RU calculates the brake release speed (S10).
3). The driver releases the brake pedal BP slightly faster than usual or at a normal speed in order to perform a brake operation on a gentle uphill or a flat ground. Therefore,
In the course of performing the brake operation, the brake operation release speed exceeds the threshold value (S104, see FIG. 11B).

When the brake release speed exceeds the threshold value (time t ₀ ), the control unit CU outputs a control current I having a predetermined current value I ₀ and supplies it to the solenoid valve SV (S10).
5, see FIG. 11 (c)). As a result, the solenoid valve SV is turned off. In addition, as shown in FIG.
_The reason why the braking force decreases for a while from ₀ is that the supplied brake fluid pressure is high on the wheel cylinder WC side, and the supplied current value I ₀
In this case, the solenoid valve SV cannot be turned off, and the communication state is apparently maintained.

[0161] Incidentally, the control unit CU and simultaneously the control current I of the current value I ₀ is supplied to the solenoid valve SV, the control current I of the current value I ₀ in the first reduction speed is predetermined It begins to gradually decrease (S107). Therefore, the braking force, which has been reduced in accordance with the brake operation amount,
Under the pressure control state of the solenoid valve SV based on the control current I gradually decreasing at the first decreasing speed, the pressure gradually decreases (see FIG. 11D). Note that the vehicle is restrained from retreating by the braking force that is held while gradually decreasing.

When the brake operation by the driver is completed and the brake switch BSW is turned off, the engine starts automatically (see FIG. 11A), and the driving force starts to increase after a predetermined slight time lag (see FIG. 11A). Outside). Even when the brake switch BSW is turned off, the solenoid valve SV is in the pressure regulating state, so that the solenoid valve SV does not enter the communicating state (S109, S110). When it is determined that the creep has risen due to the increase in the driving force (time t ₁ , S10
6) Since the starting drive force is generated to such an extent that the vehicle does not move backward, the control unit CU issues the control current I at the second reduced speed.
Is reduced until the communication state is established (S108,
FIG. 11 (c)). As a result, the braking force acting on the vehicle disappears (see FIG. 11D), and the vehicle can be smoothly started without any uncomfortable feeling. By the way, FIG.
The current having a small value indicated by the two-dot chain line is for compensating the operation delay of the solenoid valve SV (see FIG. 13 described later).
And FIG. 15).

[Stop → Start; Downhill] On the other hand, on the downhill (see the dashed line in FIG. 11), the brake operation release speed does not reach the threshold value (F_BKTH = 0), so the brake force holding unit RU operates. do not do. Therefore, the braking force depends on the driver's braking operation. In this manner, on a downhill, by setting the braking force in accordance with the braking operation of the driver, it is possible to smoothly advance at a low speed due to its own weight. Incidentally, in the case of this vehicle, the engine automatically starts when the vehicle moves forward (moves) (see FIG. 8).

As described above, according to the vehicle according to the first embodiment, the vehicle does not retreat on an uphill, and the vehicle can smoothly advance at a slow speed by its own weight on a downhill. You can take off. If the solenoid valve is a proportional solenoid valve and the brake fluid pressure on the master cylinder side is higher than the set control current value, the solenoid valve cannot be shut off and the communication Will be maintained. Therefore, even when the control unit supplies a certain large current value to the solenoid valve on a downhill, the brake operation is performed with a brake fluid pressure higher than the brake fluid pressure that can shut off the solenoid valve with this current value. In such a case, the presence of the solenoid valve does not hinder the driver's braking operation. If it is not necessary to gradually reduce the braking force by using an electromagnetic valve, a general electromagnetic valve that can create a normal communication state and a shut-off state can also be used.

Second Embodiment Next, a description will be given of a vehicle (vehicle with a brake force holding device) according to a second embodiment. In addition, about the same member, element, etc. as 1st Embodiment, the drawing used in 1st Embodiment is considered and the same code | symbol is attached | subjected and the description is abbreviate | omitted.

The vehicle according to the second embodiment has all the components of the vehicle according to the first embodiment. In addition, in the vehicle according to the second embodiment, the brake force control device applies a larger brake force to the vehicle as the brake operation release speed (the increase rate of the brake operation release speed) is larger.

{System Configuration of Vehicle, etc.} Brake Force Holding Apparatus >> The system configuration of the vehicle, etc. and the braking force holding apparatus according to the second embodiment are the same as those of the first embodiment described with reference to FIGS. Since the system configuration and the like of the vehicle according to the embodiment and the braking force holding device are the same, description thereof will be omitted. However, the control unit C of the braking force control unit RU
U is a detection value V_BG from the brake operation amount detector BG
, The brake operation release speed is calculated, and the brake operation release speed is further differentiated with respect to time to calculate an increase rate of the brake operation release speed when the brake operation release speed exceeds a threshold value. Then, as the rate of increase in the brake operation release speed increases, the control unit CU supplies the control current I having a large current value to the solenoid valve SV, and causes the vehicle to apply (hold) a large braking force. On the other hand, as the rate of increase of the brake operation release speed is smaller, the control unit CU supplies the control current I having a smaller current value to the solenoid valve SV to cause the vehicle to apply (hold) a smaller braking force.

Here, the brake release speed (maximum value)
Instead, the increase rate of the brake release speed at the time when the threshold value is exceeded is used as a parameter for the following reason. Originally, the braking force should be held in accordance with the maximum value of the brake release speed. However, the vehicle according to the second embodiment may increase the braking force regardless of the depression of the brake pedal BP. Can not. Therefore, when the maximum value of the brake operation release speed appears after exceeding the threshold value, the braking force is smaller than at the time of the threshold value,
This is because even if the braking force is held at this point, the braking force to be held is small, and the vehicle may retreat. Incidentally, the threshold value is rarely the maximum value of the brake operation release speed, and the brake operation release speed continues to increase even after the threshold value is exceeded, and the maximum value of the brake operation release speed appears some time after the threshold value is exceeded That is the most. In this case, the braking force is considerably lower than at the threshold. If the value of the increase rate of the brake operation release speed at the time when the threshold value is exceeded is large, it can be estimated that the maximum value of the brake operation release speed will be a large value. This is because if the value of the increase rate is small, it can be estimated that the maximum value of the brake operation release speed becomes a small value. And, as described above, the maximum value of the brake operation release speed and the gradient of the place where the vehicle is stopped are:
This is because there is a strong relationship.

As described above, by using the rate of increase of the brake release speed as a parameter, it is possible to maintain the braking force in accordance with the gradient of the place where the vehicle is stopped. In other words, if the rate of increase in the brake operation release speed is large, the vehicle is on a steep uphill slope, and the force for retreating the vehicle is large. On the other hand, if the rate of increase of the brake operation release speed is small, the vehicle is on a gentle uphill or on a flat ground, and the force for retreating the vehicle is small. By the way, when the braking force release speed is less than the threshold value, the vehicle is going downhill, and the vehicle has forward force due to its own weight.
The operation of the brake force holding device RU is prohibited, and the brake force is not held (according to the driver's brake operation). Therefore, by using the increase rate of the brake operation release speed as a parameter, the vehicle can be started more smoothly without excessive or insufficient braking force according to the gradient of the place where the vehicle is stopped.

In the case of a vehicle in which the braking force can be increased irrespective of the depression of the brake pedal BP,
Even if the maximum value appears after the brake release speed exceeds the threshold value, it is possible to maintain the brake force according to the maximum value or the brake release speed that changes from moment to moment (brake force). Can be increased or decreased.) By the way, the brake force is applied to the brake pedal BP
Vehicles that can be increased irrespective of the depression of the vehicle include a vehicle equipped with a traction control system (TCS), a vehicle equipped with a vehicle body stabilization device (VDC), and the like.

{Specific Vehicle Control} The specific vehicle control in the second embodiment is the same as the specific vehicle control in the first embodiment. Therefore, the description is omitted. However, for [in the case where the braking force is held], the control unit CU sets the brake operation amount (V_
BG), the brake operation release speed is calculated, and when the brake operation release speed exceeds the threshold value, the increase rate of the brake operation release speed at the time when the brake operation release speed exceeds the threshold value is calculated. Further, the control unit CU calculates a current value of the control current I to be supplied to the solenoid valve SV from the calculated increase rate of the brake release speed, and supplies the control current I to the solenoid valve SV.
The magnitude of the current value of the control current I depends on the gradient of the place where the vehicle stops.

<< Control Time Chart >> Next, how the above-described vehicle according to the second embodiment performs control during traveling will be described with reference to FIGS. 12 and 13. FIG. FIG. 12 is a flowchart of the braking force control in the vehicle braking force holding device according to the second embodiment. FIG. 13 is a control time chart of the vehicle according to the second embodiment. The vehicle stops on a steep uphill (solid line in FIG. 13) and stops on a gentle uphill or flat ground (dashed-dotted line in FIG. 13). The position switch PSW and the mode switch MSW of the vehicle are not changed in the D mode D range.

[Deceleration → Stop] First, when the vehicle is running (by the way, vehicle speed> 5 km / h), when the driver releases the accelerator pedal (ie, when the throttle is turned off), the driving force control unit DCU runs. A strong creep command (F_MSCRP) is issued to bring the vehicle into a strong creep state during running (F_MSCRPON) (see FIGS. 4A and 4B).
Therefore, the driving force is reduced as compared with the strong creep state (F_SCRPON).

Further, when the driver releases the accelerator pedal and depresses the brake pedal BP (ie, when the brake switch BSW is turned on),
The braking force increases. When the brake pedal BP is continuously depressed and the vehicle speed becomes 5 km / h, the driving force control unit DCU issues a weak creep command (F_WCR).
P) to make a weak creep state (F_WCRPON) (see FIGS. 4A and 4B). At this time, the driving state changes from the strong creep state to the weak creep state, so that the driver does not feel a strong deceleration feeling.

Then, the vehicle stops and the vehicle speed becomes 0 km / h. The driver continues to depress the brake pedal BP in order to maintain the vehicle stopped. Therefore, the engine automatically stops (see FIG. 5). Here, the brake force control unit RU operates until the brake release speed exceeds the threshold value (F
_BKTH = 1) Since it does not operate, the solenoid valve SV is in a communicating state (see FIG. 3). This state corresponds to S201 in the flowchart of FIG.

[Stop → Start; Steep Uphill] Next, in order to start the vehicle from the steep uphill (see the solid line in FIG. 13), the driver operates the brake to operate the brake pedal BP.
To start releasing (see FIG. 13 (a)). Then, the braking force starts to decrease (see FIG. 13D). At this time, since the solenoid valve SV is not in either the pressure regulation state or the shutoff state (S202), the brake force control unit RU calculates the brake operation release speed (S203). The driver quickly releases the depression of the brake pedal BP in order to perform a brake operation on a steep uphill. Accordingly, the brake operation release speed instantaneously exceeds the threshold value in the process of performing the brake operation (S204, see FIG. 13B).

When the brake operation release speed exceeds the threshold value (time t ₀ ), the rate of increase (a → a ₁ ) of the brake operation release speed at the time when the brake operation release speed exceeds the threshold value is calculated (S205, FIG. 1).
3 (b)). Then, the current value of the control current I to be supplied to the solenoid valve SV from the calculated value a ₁ to calculate (S206),
Supplying a large current value I ₁ to the solenoid valve SV (S207,
FIG. 13 (c)). Since the supplied current value I ₁ is a value corresponding to the brake fluid pressure held on the wheel cylinder WC side, the solenoid valve SV is immediately shut off (see FIG. 13D).

[0178] Next, the control unit CU and simultaneously the control current I of the current value I ₁ is supplied to the solenoid valve SV, the current value I ₁ of the control current I in the first reduction speed is predetermined Gradually begins to decrease (S209). Accordingly, the braking force gradually decreases under the pressure regulating state of the solenoid valve SV based on the control current I decreasing at the first decreasing speed (see FIG. 13D). Note that the vehicle is restrained from retreating by the braking force that is held while gradually decreasing.

When the driver finishes the braking operation and turns off the brake switch BSW, the engine starts automatically (see FIG. 13A), and the driving force starts increasing after a predetermined slight time lag (see FIG. 13A). Outside). Even when the brake switch BSW is turned off, the solenoid valve SV is in the pressure regulating state, so that the solenoid valve SV does not enter the communicating state (S211 and S212). When it is determined that the creep has risen due to the increase in the driving force (time t ₁ , S20
8) Since the starting drive force is generated to such an extent that the vehicle does not move backward, the control unit CU issues the control current I at the second reduced speed.
Is reduced until the communication state is established (S210,
FIG. 13 (c)). As a result, the braking force acting on the vehicle disappears (see FIG. 13D), and the vehicle starts running smoothly.

[Stop → Start; gentle uphill (flat)] On the other hand, on a gentle uphill or flat (see the dashed line in FIG. 13), the brake pedal BP is released more slowly than a steep uphill. (See FIG. 13A).
Therefore, the brake operation release speed calculated in S203 is
It becomes smaller than in the case of a steep uphill, and at the same time, the speed at which the brake operation release speed exceeds the threshold becomes slower than in the case of a steep uphill (time t ₀ ′, see FIG. 13B). For this reason, the rate of increase (a → a ₂ ) of the brake operation release speed decreases (S205). Control unit CU, the current value of the control current I to be supplied to the solenoid valve SV from increase a ₂ of the small brake operating release rate was calculated (S206), a small current value I
₂ is supplied to the solenoid valve SV (S207).

The solenoid valve SV is supplied with the control current I of the current value I _2. However, the brake fluid pressure on the wheel cylinder WC side is high, so that the solenoid valve SV cannot be shut off immediately at time t ₀ ′. After the apparent communication state continues, the pressure adjustment state is established, and the brake fluid pressure gradually decreases (FIG. 13).
(c), (d)). The control current I continues to decrease at a predetermined first decreasing speed (S209). A braking force that is maintained while gradually decreasing acts on the vehicle.

Then, when the driver's braking operation is completed,
When the brake switch BSW is turned off, the engine
Dynamic start (see Fig. 13 (a))
Drive power starts to increase (not shown) after creeping and creeping
Rise is achieved (time t ₁’). The control unit CU
When it is determined that a reap rise has occurred (S208), a second decrease is performed.
The current value of the control current I is reduced at a low speed until the communication state is established.
(S210, see FIG. 13C). This allows the car
The braking force acting on both sides disappears (see FIG. 13 (d)).
), And a smooth start of the vehicle is realized. In addition, creep
Until the start-up is achieved, the solenoid valve SV is in the pressure regulating state
The brake switch BSW is turned off
However, the solenoid valve SV does not immediately enter the communication state (S
211, S212).

As described above, according to the vehicle according to the second embodiment, the braking force can be applied without excess or deficiency according to the situation of the stopping place of the vehicle, and the vehicle can be started more smoothly. .

Third Embodiment Next, a description will be given of a vehicle (vehicle with a brake force holding device) according to a third embodiment. In addition, about the same member, element, etc. as 1st Embodiment, the drawing used in 1st Embodiment is considered and the same code | symbol is attached | subjected and the description is abbreviate | omitted.

The vehicle according to the third embodiment has all the components of the vehicle according to the first embodiment. In addition, in the vehicle according to the third embodiment, the braking force control device acts on the vehicle by decreasing the gradually decreasing speed at which the braking force is gradually reduced as the brake operation release speed (the increasing rate of the brake operation release speed) is larger. Let it.

{System Configuration of Vehicle, etc.} Brake Force Holding Apparatus >> The system configuration of the vehicle, etc. and the braking force holding apparatus according to the third embodiment are the same as those of the first embodiment described with reference to FIGS. Since the system configuration and the like of the vehicle according to the embodiment and the braking force holding device are the same, description thereof will be omitted. However, the control unit C of the braking force control unit RU
U is a detection value V_BG from the brake operation amount detector BG
The brake operation release speed is calculated based on the above, and the brake operation release speed is further differentiated with respect to time to calculate the increase rate of the brake operation release speed when the brake operation release speed exceeds the threshold value. Then, as the rate of increase of the brake operation release speed increases, the control unit CU gradually reduces the braking force at a small gradually decreasing speed. On the other hand, as the rate of increase of the brake operation release speed is smaller, the control unit CU gradually reduces the braking force at a larger gradually decreasing speed.

Here, brake operation release speed (maximum value)
Instead of using the increase rate of the brake release speed at the time when the threshold value is exceeded as a parameter, as described in the second embodiment, there is a strong relationship with the gradient of the place where the vehicle is stopped. Because there is.

That is, by using the increase rate of the brake operation release speed as a parameter, the braking force can be maintained in accordance with the degree of gradient of the place where the vehicle is stopped. That is, if the rate of increase in the brake operation release speed is large, the vehicle is on a steep ascending slope, and the force for retreating the vehicle is large, so that the braking force is maintained for a long time. On the other hand, if the rate of increase in the brake operation release speed is small, the vehicle is on a gentle uphill or on a level ground, and the force for retreating the vehicle is small. Therefore, the braking force is kept shorter than in the case of a steep uphill. By the way, if the braking force release speed is less than the threshold, it is a downhill,
Since the vehicle generates a forward force due to its own weight, the operation of the brake force holding device RU is prohibited, and the brake force is not held (according to the driver's brake operation). Therefore, by using the increase rate of the brake operation release speed as a parameter, the vehicle can be started more smoothly without excessive or insufficient braking force according to the gradient of the place where the vehicle is stopped.

{Specific Vehicle Control} The specific vehicle control in the third embodiment is the same as the specific vehicle control in the first embodiment. Therefore, the description is omitted. However, for [in the case where the braking force is held], the control unit CU sets the brake operation amount (V_
BG), the brake operation release speed is calculated, and when the brake operation release speed exceeds the threshold value, the increase rate of the brake operation release speed at the time when the brake operation release speed exceeds the threshold value is calculated. Further, the control unit CU calculates a decrease rate of the first decrease speed for gradually decreasing the current value of the control current I supplied to the solenoid valve SV from the calculated increase rate of the brake release speed, and based on the calculated value, Thus, the value of the control current I supplied to the solenoid valve SV is reduced. Thereby, the braking force gradually decreases based on the first reduction speed obtained by the calculation. That is, if the decreasing rate of the first decreasing speed is large, the braking force gradually decreases, and the braking force is kept short. On the other hand, if the decreasing rate of the first decreasing speed is small,
The braking force gradually decreases, and the braking force is maintained for a long time. The rate of decrease of the first decreasing speed at which the current value of the control current I is decreased depends on the gradient of the place where the vehicle is stopped.

<< Control Time Chart >> Next, how the above-described vehicle according to the third embodiment performs control during traveling will be described with reference to FIGS. 14 and 15. FIG. 14 is a flowchart of the braking force control in the vehicle braking force holding device according to the third embodiment. FIG. 15 is a control time chart of the vehicle according to the third embodiment. The vehicle stops on a steep uphill (solid line in FIG. 15) and stops on a gentle uphill or flat ground (dashed-dotted line in FIG. 15). The position switch PSW and the mode switch MSW of the vehicle are not changed in the D mode D range.

[Deceleration → Stop] First, when the vehicle is running (by the way, vehicle speed> 5 km / h), when the driver releases the accelerator pedal (ie, when the throttle is turned off), the driving force control unit DCU runs. A strong creep command (F_MSCRP) is issued to bring the vehicle into a strong creep state during running (F_MSCRPON) (see FIGS. 4A and 4B).
Therefore, the driving force is reduced as compared with the strong creep state (F_SCRPON).

Further, when the driver releases the accelerator pedal and depresses the brake pedal BP (that is, when the brake switch BSW is turned on), the braking force increases. Then, when the brake pedal BP is continuously depressed and the vehicle speed becomes 5 km / h, the driving force control unit DCU issues a weak creep command (F_WCRP).
Is issued to bring the weak creep state (F_WCRPON) (see FIGS. 4A and 4B). At this time, the driving state changes from the strong creep state to the weak creep state, so that the driver does not feel a strong deceleration feeling.

Then, the vehicle stops and the vehicle speed becomes 0 km / h. The driver continues to depress the brake pedal BP in order to maintain the vehicle stopped. Therefore, the engine automatically stops (see FIG. 5). Here, the brake force control unit RU operates until the brake release speed exceeds the threshold value (F
_BKTH = 1) Since it does not operate, the solenoid valve SV is in a communicating state (see FIG. 3). This state corresponds to S301 in the flowchart of FIG.

[Stop → Start; Steep Uphill] Next, in order to start the vehicle from a steep uphill (see the solid line in FIG. 15), the driver operates the brake to operate the brake pedal BP.
To start releasing (see FIG. 15 (a)). Then, the braking force starts to decrease (see FIG. 15D). At this time, since the solenoid valve SV is not in either the pressure regulation state or the shutoff state (S302), the brake force control unit RU calculates the brake operation release speed (S303). The driver
In order to perform a braking operation on a steep uphill, the depression of the brake pedal BP is quickly released. Therefore, the brake operation release speed instantaneously exceeds the threshold value in the process of performing the brake operation (S304, see FIG. 15B).

When the brake operation release speed exceeds the threshold value (time t ₀ ), the increase rate (a → a ₁ ) of the brake operation release speed at the time when the brake operation release speed exceeds the threshold value is calculated (S305, FIG. 15B). reference).

At the same time, when the brake release speed exceeds the threshold value, the control unit CU outputs a control current I having a predetermined current value I ₀ and supplies it to the solenoid valve SV (S306, see FIG. 15 (c)). ). As a result, the solenoid valve SV is turned off. As shown in FIG. 15 (d), the reason why the braking force is reduced for a while according to the brake operation amount from time t ₀ is that the braking force is reduced on the wheel cylinder WC side as described in the first embodiment. This is because the held brake fluid pressure is large.

By the way, the control unit CU calculates the rate of decrease of the current value I ₀ of the control current I in the pressure regulation state, that is, the rate of decrease of the first rate of decrease from the rate of increase of the brake operation release speed calculated previously. (S308). And the solenoid valve S
From the current value I ₀ of the control current I supplied to V, the current value is immediately reduced at the first decreasing speed (S309, see FIG. 15C). Therefore, the braking force, which has been reduced in accordance with the brake operation amount, is gradually reduced immediately under the pressure regulation state of the solenoid valve SV based on the control current I decreasing at the first decreasing speed (FIG. 15). (d)). The vehicle is restrained from retreating by a braking force that is held while gradually decreasing.

Then, when the driver's braking operation is completed,
When the brake switch BSW is turned off, the engine
Dynamic start (see Fig. 15 (a))
Drive power starts to increase (not shown) after creeping and creeping
Rise is achieved (time t ₀). Creep rise
Is determined (S309), the vehicle does not retreat.
Since the start driving force is generated every time, the control unit CU
The current value of the control current I at the decreasing speed of
(S310, see FIG. 15C). This
As a result, the braking force acting on the vehicle disappears (see FIG. 15).
(d)), and the vehicle is smoothly started. In addition,
The solenoid valve SV is adjusted until the reap rise is achieved.
Pressure switch, the brake switch BSW is turned off.
The solenoid valve SV does not immediately enter the open state.
(S311, S312).

[Stop → start; gentle uphill (flatland)]
On a gentle uphill or on a flat ground,
See the chain line), brakes more slowly than on steep ascents
The depression of the pedal BP is released (see FIG. 15A).
Therefore, the brake operation release speed calculated in S303 is:
It is smaller than on a steep uphill
It is time t that the crop release speed exceeds the threshold ₀’And a steep climb
Time t for slope₀(S304, FIG. 15)
(b)). Therefore, the rate of increase in the brake release speed
(A → a_Two) Becomes smaller. The control unit CU controls this small
Increase rate a of brake release speed a_TwoFrom the first decreasing speed
Is calculated (S308). This first decreasing speed
The rate of decrease in the degree is greater than when going uphill. Therefore,
Gradual deceleration of braking force is greater than when going uphill
(See FIG. 15 (d)). This is to increase the gradual rate.
To eliminate useless brake drag
is there.

Then, when the driver's braking operation is completed,
When the brake switch BSW is turned off, the engine
Dynamic start (see Fig. 15 (a))
Drive power starts to increase (not shown) after creeping and creeping
Rise is achieved (time t ₁’). Creep rise
When the control unit CU determines that the
The current value of the control current I is reduced at the decreasing speed until the communication state is established.
It decreases (S310, see FIG. 15C). This allows
The braking force acting on the vehicle disappears (see FIG. 15 (d)).
), And a smooth start of the vehicle is realized. In addition, creep
Until the start-up is achieved, the solenoid valve SV is in the pressure regulating state
The brake switch BSW is turned off
However, the solenoid valve SV does not immediately enter the communication state (S
311 and S312).

As described above, according to the vehicle according to the third embodiment, by gradually changing the speed of the braking force,
By applying the braking force without any excess or shortage according to the situation of the stop place of the vehicle, the vehicle can be started more smoothly.

As described above, the present invention is not limited to the above-described embodiment, but may be embodied in various forms. For example, the braking force holding device is constituted by means acting on the brake fluid pressure as means acting on the braking force, but is not particularly limited as long as it can act on the braking force. Also,
The present invention can be applied not only to a vehicle equipped with an automatic transmission but also to a vehicle equipped with a manual transmission. Further, the inventions described in claims 1 to 4 can be freely combined and implemented. Of course, the above-described second embodiment and the third embodiment can be implemented in combination. Further, the holding of the braking force may be started when the vehicle stops. Alternatively, the braking force may be held at a low vehicle speed of, for example, 10 km / h or less or 5 km / h or less.

[0203] For example, in the case of a vehicle in which the braking force can be increased irrespective of the depression of the brake pedal, the temporarily reduced braking force can be increased in accordance with the brake release speed. For example, it is assumed that there is a case where the depression of the brake pedal is gradually released and the depression of the brake pedal is released at a stretch when the vehicle feels backward. In this case, it is also possible to detect the brake operation release speed at the time of releasing the brake pedal and to keep the brake force higher than at the time when the retreat occurs. Further, in the case of a vehicle capable of increasing the braking force irrespective of the depression of the brake pedal, it is possible to adopt a configuration in which the braking force is gradually increased or decreased according to the brake operation release speed that changes every moment. In the case of the vehicle described in the above embodiment, after the brake release speed exceeds the threshold, the brake force is sequentially changed based on the value of the brake release speed within the range of the brake force at each time thereafter. It is also possible to adopt a configuration in which the

[0204]

According to the vehicle with the braking force retaining device according to the first aspect of the present invention, when climbing an uphill, the braking force acts on the vehicle even after the brake operation is released (after the brake pedal is released). Thus, the vehicle can be started without retreating. Also, when going downhill, keep the braking force small (do not operate the braking force holding device)
Therefore, it is possible to perform a slow forward movement by loosening the depression of the brake pedal. In addition, in this configuration, the inclination detecting means and the reverse gear switch are not particularly required.

Further, according to the vehicle with the braking force holding device according to the second aspect of the present invention, it is possible to smoothly advance at a low speed on a downhill and to eliminate unnecessary operation of the braking force holding device. Can be.

Further, according to the vehicle with the braking force holding device according to the third aspect of the present invention, the vehicle can be started more smoothly according to the degree of the gradient.

According to the vehicle with the braking force holding device according to the fourth aspect of the present invention, the vehicle can be started smoothly by harmonizing the gradually decreasing braking force with the increasing starting driving force. . In addition, a steeper uphill which tends to retreat has a larger (greater) brake force for a longer time, so that the vehicle can start smoothly on an uphill.
On the other hand, by gradually increasing the deceleration speed as the release speed of the brake operation amount is smaller, useless brake dragging on a downhill can be eliminated.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a vehicle with a brake force holding device according to a first embodiment.

FIG. 2 is a configuration diagram of a brake force holding device of the vehicle with the brake force holding device according to the first embodiment.

FIG. 3 is a control logic for holding the braking force of the braking force holding device of the vehicle with the braking force holding device according to the first embodiment.

4A is a control logic for setting a weak creep state in the driving force control device of the vehicle with a brake force holding device according to the first embodiment; FIG. 4B is a control logic for setting a strong creep state during running; c) is a control logic for setting the medium creep state.

FIG. 5 is a control logic for automatically stopping the engine of the prime mover stopping device of the vehicle with the brake force holding device according to the first embodiment.

FIG. 6A is a control logic (first example) of the brake force holding device of the vehicle with the brake force holding device according to the first embodiment, which releases the holding of the braking force due to the generation of the starting drive force in the vehicle itself. (B) is a control logic for releasing the holding of the braking force from the viewpoint of fail-safe and the like (first decreasing speed → communication state), and (c) is creep. Is a control logic for judging the rise of the signal.

FIG. 7A is a control logic (vehicle retreat detection version) for setting a strong creep state in the driving force control device of the vehicle with a brake force holding device according to the first embodiment, and FIG. The control logic (vehicle movement detection version).

8A is a control logic (vehicle retreat detection version) for automatically starting an engine, and FIG.
Is a control logic (vehicle movement detection version) for automatically starting the engine.

9A and 9B are an example of a vehicle backward detection method for a vehicle with a brake force holding device according to the first embodiment, wherein FIG. 9A is a configuration diagram of vehicle backward detection, and FIG. (C) is the pulse phase of the directional rotation in FIG.

FIG. 10 is a flowchart of brake force control in the brake force holding device of the vehicle with the brake force holding device according to the first embodiment.

FIG. 11 is a control time chart of the vehicle with the brake force holding device according to the first embodiment. (A) shows the brake operation amount, (b) shows the brake release speed, (c) shows the current value of the solenoid valve, and (d) shows the braking force.

FIG. 12 is a flowchart of brake force control in the brake force holding device of the vehicle with the brake force holding device according to the second embodiment.

FIG. 13 is a control time chart of the vehicle with the brake force holding device according to the second embodiment. (A) shows the brake operation amount, (b) shows the brake release speed, (c) shows the current value of the solenoid valve, and (d) shows the braking force.

FIG. 14 is a flowchart of brake force control in the brake force holding device of the vehicle with the brake force holding device according to the third embodiment.

FIG. 15 is a control time chart of the vehicle with the brake force holding device according to the third embodiment. (A) shows the brake operation amount, (b) shows the brake release speed, (c) shows the current value of the solenoid valve, and (d) shows the braking force.

[Explanation of symbols]

 BK: brake device (brake) RU: brake force holding device

Claims (4)

[Claims] 1. A vehicle provided with a brake force holding device for continuously applying a braking force to a vehicle even after a driver releases a brake operation until a start driving force is generated in the vehicle itself, the brake operation amount being controlled by the driver. And the brake force holding device is operated based on the release speed of the brake operation amount. 2. The vehicle with a brake force holding device according to claim 1, wherein the brake force holding device is operated on condition that a release speed of the brake operation amount exceeds a predetermined value. 3. The brake force holding device according to claim 1, wherein the brake force holding device applies a larger brake force to the vehicle as the release speed of the brake operation amount increases. Attached vehicle. 4. The braking force holding device according to claim 1, wherein the braking force acting on the vehicle is gradually reduced, and the gradually decreasing speed at which the braking force is gradually reduced is reduced as the release speed of the brake operation amount is increased. The vehicle with the brake force holding device according to any one of claims 1 to 3.