JP3213887B2 - Vehicle with brake fluid pressure holding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION In the present invention, the brake fluid pressure passage between the master cylinder and the wheel cylinder is interrupted by an electromagnetic valve so that the brake fluid pressure can be maintained in the wheel cylinder even after the brake pedal is released. The present invention relates to a vehicle with a brake fluid pressure holding device including the brake fluid pressure holding device.

[0002]

2. Description of the Related Art Japanese Patent Application No. 10-370249 filed by the present applicant.
When the traveling position of the transmission is selected below a predetermined low vehicle speed, the driving force transmission capacity (engaging force) of the starting clutch is switched between a large state and a small state according to the depression state of the brake pedal. When the brake pedal is depressed, the driving force transmitted from the prime mover to the driving wheels is smaller than when the brake pedal is released when the driving force transmission capacity of the starting clutch is reduced and the driving force transmission capacity of the starting clutch is increased. A driving force transmission capacity control device (driving force reducing device) for a starting clutch which is reduced in size to improve fuel efficiency, and a brake fluid pressure passage between a master cylinder and a wheel cylinder is cut off to communicate with the brake fluid pressure passage in a wheel cylinder. A solenoid valve that switches between a shut-off position that holds the brake fluid pressure and a communication position that allows communication of the brake fluid pressure passage is provided. The solenoid valve is switched to the shut-off position on condition that the driving force transmission capacity of the clutch is in the small state, and the driver sufficiently depresses the brake pedal on the slope, holds the brake fluid pressure, and starts the clutch. When the driving force transmission capacity of the vehicle increases from the small state to the large state and a starting drive force against the slope is generated in the vehicle itself, the solenoid valve is returned to the communication position to release the brake fluid pressure. A vehicle with a brake fluid pressure holding device including the pressure holding device is disclosed.

[0003] In some cases, the driver depresses the accelerator pedal with the right foot and simultaneously depresses the brake pedal with the left foot to increase the driving force generated on the driving wheels, and then release the brake pedal to start the vehicle. In this case, if the driving force transmission capacity of the starting clutch is small, the driving force generated on the driving wheels cannot be increased. That is, even if the output of the prime mover is increased, if the driving force transmission capacity of the starting clutch is small, all the output of the prime mover cannot be transmitted to the drive wheels. In other words, no matter how high the output of the prime mover is, only the driving force corresponding to the driving force transmission capacity of the starting clutch is transmitted to the driving wheels. Therefore, in the vehicle shown in the prior art, when actually configuring the driving force transmission capacity control device for the starting clutch, the driving force is divided into a case where the accelerator pedal is depressed and a case where the accelerator pedal is released. It is necessary to adopt a configuration in which the driving force transmission capacity of the starting clutch is increased to the above-mentioned large state or more irrespective of the depressed state of the brake pedal BP.

However, if the driving force transmission capacity of the starting clutch is set to be greater than the large state when the accelerator pedal is depressed regardless of the depressed state of the brake pedal, in the vehicle shown in the prior art, the brake fluid pressure holding device is not provided. In order to return the solenoid valve to the communication position when the driving force transmission capacity of the starting clutch increases from the small state to the large state, for example, when the vehicle is stopped, only the brake pedal is depressed with the left foot and the right foot is further used. When the accelerator pedal is depressed and the brake pedal and the accelerator pedal are simultaneously depressed, the time when the driving force transmission capacity of the starting clutch increases from the small state to the large state after the accelerator pedal is depressed with the right foot. With this, the solenoid valve is returned to the communication position. In this case, when the accelerator pedal is depressed, the depression of the brake pedal is slightly loosened compared to the previous depression state,
When the solenoid valve is returned to the communication position, the brake fluid pressure generated from the master cylinder may be lower than the brake fluid pressure held in the wheel cylinder. When returned to the position, the high hydraulic pressure held in the wheel cylinder is instantaneously transmitted to the master cylinder side, which may cause a shock to the left foot of the driver who is depressing the brake pedal.

[0005] The present invention provides a brake fluid pressure holding device capable of starting after increasing the driving force without giving a shock to the driver's foot depressing the brake pedal even when the brake pedal and the accelerator pedal are depressed simultaneously. It is an object to provide an attached vehicle.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention shuts off the solenoid valve of the brake fluid pressure holding device uniformly when the driving force transmission capacity of the starting clutch increases from a small state to a large state. Instead of returning from the position to the communication position, the electromagnetic valve is returned from the shut-off position to the communication position on condition that the depression of the brake pedal is released. That is, the present invention has solved the above-mentioned problems.
Of the vehicle with the brake fluid pressure holding device is equal to or less than the first predetermined vehicle speed.
When the traveling position is selected in the vehicle transmission
When the accelerator pedal is released,
Increases the driving force transmission capacity of the starting clutch according to the depression state
Switch between the threshold state and the small state and depress the brake pedal.
When starting, keep the driving force transmission capacity of the starting clutch small.
To increase the driving force transmission capacity of the starting clutch.
Compared to when the brake pedal is released.
While reducing the driving force transmitted to the driving wheels,
When the pedal is depressed, check whether the brake pedal is depressed.
The driving force transmission capacity of the starting clutch is large.
A starting force transmission capacity control device for the starting clutch,
Brake fluid pressure between master cylinder and wheel cylinder
The communication of the brake fluid passage to the road
Position for holding the brake fluid pressure in the cylinder and the brake
Solenoid valve that switches to a communication position that allows communication of the hydraulic pressure passage
And the brake pedal is depressed below the second predetermined vehicle speed
When the solenoid valve is switched to the shut-off position on condition that
The brake pedal and the accelerator pedal when the vehicle starts
Are stepped on at the same time,
The driving force transmission capacity of the starting clutch is greater than the large state
And the brake pedal is released
Brake fluid pressure return to return the solenoid valve to the communication position on condition
And a holding device. With this configuration, for example, when the vehicle is stopped and the accelerator pedal is further depressed with the right foot from the state where only the brake pedal is depressed with the left foot, the driving force transmission capacity of the starting clutch changes from the small state to the large state. Alternatively it increases more than that, unless the brake pedal is released at that point be increased to more than the large state is in the solenoid valve is subsequently closed position, thereafter when the depression of the brake pedal is released The solenoid valve returns to the communication position.

Here, the "driving force transmission capacity" of the starting clutch means the maximum driving force (driving torque) that can be transmitted by the starting clutch. The driving force transmission capacity control device can variably control the driving force transmission capacity.
The "first predetermined vehicle speed" is used for controlling the state of the driving force transmission capacity by the driving force transmission capacity control device, and the "second predetermined vehicle speed" is used for controlling the holding of the brake fluid pressure by the brake fluid pressure holding device. And both vehicle speeds are 0km / h (vehicle stopped)
Alternatively, it means the vehicle speed immediately before the vehicle stops, but the two vehicle speeds do not necessarily have to be set to the same vehicle speed. In the present embodiment, as an example, the “first predetermined vehicle speed” is 5 km / h.
In addition, the "second predetermined vehicle speed" is set to 0 km / h.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vehicle with a brake fluid pressure holding device according to the present invention will be described in detail. A vehicle with a brake hydraulic pressure holding device (hereinafter, referred to as a “vehicle”) includes a driving force transmission capacity control device for a starting clutch and a brake hydraulic pressure holding device. In the following embodiments, a vehicle in which the transmission is a belt-type continuously variable transmission (hereinafter, referred to as “CVT”) will be described, but the transmission may be a stepped automatic transmission with a torque converter. .

<< General System Configuration of Vehicle >> An example of the general system configuration of a vehicle will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of a system configuration of a vehicle with a brake fluid pressure holding device according to the present embodiment. The vehicle includes an engine 1 and a motor 2 as prime movers, and a CV as a transmission.
T3 is provided. The CVT 3 incorporates a driving force transmission capacity control device (hereinafter, referred to as a “driving force transmission capacity control device”) DCU of a starting clutch described later.

[Description of Devices] The engine 1 is controlled by a fuel injection electronic control unit (hereinafter referred to as “FIECU”). The FIECU is integrally formed with a management electronic control unit (hereinafter, referred to as “MGECU”), and is provided in a fuel injection / management electronic control unit (hereinafter, referred to as “FI / MGECU”) 4. The motor 2 is a motor electronic control unit (hereinafter referred to as “MO”).
TECU). In addition, CVT3
Is controlled by a CVT electronic control unit (hereinafter referred to as “CVT ECU”) 6. The CVT ECU 6 includes a control unit CU that controls a driving force transmission capacity control unit DCU and a brake hydraulic pressure holding unit RU described later.

The engine 1 is an internal combustion engine that utilizes heat energy, and drives the drive wheels 8.8 via the CVT 3 and the drive shaft 7. The drive wheels 8.8 are configured to be braked by a hydraulic brake device BC (see FIG. 3) described later. 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 stop 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 in FIG. Motor 2
Has a regenerative mode in which kinetic energy due to the 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. Have.

The CVT 3 continuously changes the speed ratio 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 CVT 3 includes a driving force transmission capacity control unit DCU, and when transmitting the driving force generated by the prime mover to the driving wheels 8.8, the driving force transmission capacity of the starting clutch (hereinafter referred to as “driving force transmission capacity”). It can be transmitted by increasing or decreasing or changing. For example, when the driving force transmission capacity is reduced, the slip amount of the starting clutch is increased as compared with the case where the driving force transmission capacity is increased, and the driving force transmitted to the driving wheels 8.8 is also increased when the driving force transmission capacity is increased. It is smaller than that.

The driving force transmission capacity control unit DCU will be described later in detail.
A vehicle equipped with a CU can change the driving force of so-called creep. For example, when the driving force transmission capacity is set to “large” by the driving force transmission capacity control device DCU during idling, a “strong creep state” in which the driving force of creep is large can be created. In addition, the driving force transmission capacity is small when idling.
If set to, a "weak creep condition" can be created. In the vehicle of the present embodiment, the strong creep state is 5
It has a driving force transmission capacity that prevents the vehicle from backing up on a moderate slope. The weak creep state is a state in which there is no driving force or almost no driving force. The strong creep state and the weak creep state are in a relative relationship. A state in which the driving force is smaller than the strong creep state is a weak creep state, and a state in which the driving force is larger than the weak creep state is a strong creep state. By creating a weak creep state, the load on the engine 1 can be reduced and the hydraulic pressure supplied to the starting clutch can be reduced, so that fuel economy can be reduced. In the following description, the driving force transmission capacity is in a "small state" when "weak creep state" is set, and the driving force transmission capacity is in "large state" when it is set in "strong creep state". On the other hand, when the driving force transmission capacity is in the “small state”, the vehicle is in the “(weak driving force) weak creep state”, and when the driving force transmission capacity is in the “large state”, it is in the “(vehicle driving state)”. The driving force is in a "strong creep state".

Next, the range position (running position / non-running position) of the position switch PSW is selected by a shift lever. The range of the position switch PSW is the P range used when parking and stopping, the N range which is neutral, the R range used when running backward, the D range used when running normally, and used when sudden acceleration or strong engine braking is required. There is an L range. Of these, the three ranges of the D range, the L range, and the R range are the “travel positions”. Two ranges of the P range and the N range are “non-traveling positions”. Note that the position switch P
When the D range is selected by the SW, the mode switch MSW can be used to select the D mode as the normal driving mode and the S mode as the sports driving mode.

FI ECU included in FI / MG ECU 4
Controls the fuel injection amount so as to obtain the optimum air-fuel ratio, and controls the engine 1 as a whole. FIEC
The U and the like are transmitted with information indicating the throttle opening degree and the state of the engine 1, and control the engine 1 based on each information. MGECU included in FI / MGECU 4
Controls mainly the MOTECU 5 and determines an automatic engine stop condition and an automatic engine start condition. The information indicating the state of the motor 2 is transmitted to the MGECU, and information indicating the state of the engine 1 and the like are input from the FIECU. Also, M
The information indicating the state of the CVT 3, the information indicating the state of the engine 1, the range information of the position switch PSW, the information indicating the state of the motor 2, and the like are transmitted to the GECU. Judge the start.

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, which is also the control means CU,
It controls the gear ratio of the CVT 3, the driving force transmission capacity control unit DCU, and the brake hydraulic pressure holding unit RU (both will be described in detail later). 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 are transmitted to the CVT ECU 6.
A signal for controlling the hydraulic pressure of each cylinder of the drive pulley and the driven pulley of T3 and controlling the hydraulic pressure of the starting clutch are transmitted to the CVT 3. Furthermore, CVT ECU
Reference numeral 6 controls ON / OFF (communication position / cutoff position) of the solenoid valve SV (see FIG. 3) of the brake fluid pressure holding device RU, and sets the driving force of creep to a strong creep state or a weak creep state. Judge. Also, CVTEC
U6 includes a failure detection device DU for detecting a failure of the brake fluid pressure holding device RU. The failure detection device DU turns on the solenoid valve SV of the brake fluid pressure holding device RU.
A drive circuit for N / OFF is also provided.

The disc brakes 9.9 are driven wheels 8.8
The disk rotor, which rotates together with the disk rotor, is sandwiched between brake pads driven by a wheel cylinder WC (see FIG. 3), and a braking force is obtained by the frictional force. The brake fluid pressure of the master cylinder MC (see FIG. 3) is supplied to the wheel cylinder WC via the brake fluid pressure holding device RU.

The motor stopping device provided in this vehicle is an FI
/ MG ECU 4 and the like. The motor stop device is
When the vehicle is stopped, the engine 1 can be stopped automatically. The motor stop device is FI / MGECU4
Determines the automatic engine stop condition such as the vehicle speed of 0 km / h. The engine automatic stop condition will be described later in detail. If it is determined that all of the engine automatic stop conditions are satisfied, the FI / MGEC
An engine stop command is transmitted from U4 to the engine 1, and the engine 1 is automatically stopped. The vehicle further prevents fuel consumption from deteriorating by the automatic stop of the engine 1 by the motor stop device. When the engine 1 is automatically stopped by the motor stop device, the MGE of the FI / MGECU 4
The CU determines the engine automatic start condition. Then, when the engine automatic start condition is satisfied, the FI / MG ECU
4 transmits an engine start command to the MOTECU 5, further transmits a command to start the engine 1 from the MOTECU 5 to the motor 2, and automatically starts the engine 1 by the motor 2 and puts the engine in a strong creep state. The engine automatic start condition will be described later in detail (see FIG. 5B). Further, when the failure detection device DU detects a failure of the brake fluid pressure holding device RU, the operation of the prime mover stopping device is prohibited.

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

A signal transmitted from the FI / MG ECU 4 to the CVT ECU 6 which is also the control unit CU will be described. V_MOTRQ is an output torque value of the motor 2. F_MGSTB is a flag indicating whether or not all of the engine automatic stop conditions, which will be described later, except for the five conditions of F_CVTOK, are satisfied. Is “0”. Incidentally, when both F_MGSTB and F_CVTOK are switched to “1”, the engine 1 is automatically stopped, and when either of the flags is switched to “0”, the engine 1 is automatically started.

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_CVTOK is
The CVT 3 is in a weak creep state, the ratio (pulley ratio) of the CVT 3 is low, the oil temperature of the CVT 3 is a predetermined value or more, the brake fluid temperature is a predetermined value or more, and the brake fluid pressure holding device RU is normal (the electromagnetic pressure of the brake fluid pressure holding device RU). Valve SV (see Fig. 3)
This flag indicates whether or not the five conditions (including normal driving circuit) are satisfied. The flag is “1” when all five conditions are satisfied, and “1” when at least one condition is not satisfied. It is "0". When the engine is stopped, CV
T3 weak creep, CVT3 ratio low, CV
The condition that the oil temperature at T3 is equal to or higher than the predetermined value and the brake fluid temperature is equal to or higher than the predetermined value is maintained, and F_CVTOK is determined only by whether or not the brake hydraulic pressure holding device RU is normal. That is,
When the engine is stopped, F_CVTOK is “1” when the brake fluid pressure holding device RU is normal, and F_CVTOK is “0” when the brake fluid pressure holding device RU is out of order.
F_CVTTO is a flag indicating whether the oil temperature of the CVT 3 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. The oil temperature of the CVT 3 is estimated from the electric resistance 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 or not the range of the position switch PSW has been selected to the R range. The flag is "1" for the R range and "0" for other than the R range. F_
POSDD means that the range of the position switch PSW is D
This flag indicates whether or not the mode of the range and mode switch MSW has been selected to the D mode.
The value is "1" for the range, and "0" for modes 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 the engine 1 to the 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. Incidentally, when V_TH = 0, the throttle T where the accelerator pedal is not depressed is
In the state of H [OFF], when V_TH> 0, the throttle TH [ON] in which the accelerator pedal is depressed. V_TW is the cooling water temperature of the engine 1. V
_TA is the intake air temperature of the engine 1. Note that the brake fluid temperature of the brake fluid pressure 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 the CVT 3 to the 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.

A signal transmitted from the MOTECU 5 to the 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.

A signal transmitted from the CVT ECU 6 to the brake fluid pressure holding device RU will be described. F_SOLA
Is one solenoid valve SVA of the brake fluid pressure holding device RU.
(See FIG. 3) is a flag for turning ON / OFF.
The value is 1 when turned on, and 0 when turned off. F
_SOLB is a flag for turning on / off the other solenoid valve SVB (see FIG. 3) of the brake fluid pressure holding device RU, and is 1 when it is turned on and 0 when it is turned off.

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), which is “1” when the brake pedal BP is depressed, and “0” when the brake pedal BP is released.

<< Driving Force Transmission Capacity Control Device >> [Structure of Driving Force Transmission Capacity Control Device, etc.] The driving force transmission capacity control device DCU according to the present embodiment is incorporated in the CVT 3 and is controlled by a control unit CU built in the CVT ECU 6. Depending on the signal, the driving force transmission capacity of the starting clutch also incorporated in the CVT 3 is set to “large state”, “small state”, or “large state or more”.
Or The control of the driving force transmission capacity by the driving force transmission capacity control device DCU is performed by controlling the hydraulic pressure of a starting clutch (hydraulic multi-plate clutch) incorporated in the CVT 3. If the value of the hydraulic pressure of the starting clutch is reduced, the pressing force of the clutch plate is weakened, and the driving force transmission capacity is selected in the weak creep state.
become. When the value of the oil pressure is increased, the pressing force of the clutch plate is increased, and the driving force transmission capacity becomes a “large state” selected in the strong creep state. If the value of the oil pressure is further increased, the pressing force of the clutch plate is further increased, and the driving force transmission capacity becomes “large or more” selected during normal running. It should be noted that the driving force transmission capacity “greater than or equal to large state” means a driving force transmission capacity greater than or equal to the driving force transmission capacity including “large state”.

Whether the driving force transmission capacity of the starting clutch has an appropriate value in each state is determined based on the slip amount of the starting clutch and the like. For example, if the driving force transmission capacity is larger than an appropriate value. If it is determined, the driving force transmission capacity can be set to an appropriate value by reducing the value of the hydraulic pressure of the starting clutch. Incidentally, the control of the driving force transmission capacity in the stepped automatic transmission with the torque converter can be performed in the same manner as in the case of the CVT 3 by controlling the hydraulic pressure of the hydraulic clutch used at the time of starting.

[Basic control of driving force transmission capacity control device]
Next, the basic control of the driving force transmission capacity control device DCU will be described. 1) When the traveling position is selected in the transmission at or below the first predetermined vehicle speed, the driving force transmission capacity control unit DCU determines whether the brake pedal BP is depressed due to the depression state of the brake pedal BP. The driving force transmission capacity is set to “small state”, and when the brake pedal BP is not depressed, the driving force transmission capacity is set to “large state”.
The control unit CU determines whether or not the brake pedal BP is depressed from the signal of the brake switch BSW.

The reason why the driving force transmission capacity is set to the "small state" when the brake pedal BP is depressed in this manner is that even if the driver depresses the brake pedal BP strongly and the driving force by the engine disappears, the vehicle stops on a slope. This is to prevent the vehicle from moving backward due to its own weight. On the other hand, when the brake pedal BP is depressed and released, the driving force transmission capacity is set to the "large state" in order 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. It is.

2) The driving force transmission capacity control unit DCU sets the driving force transmission capacity to "large or larger" when the accelerator pedal is depressed regardless of the depressed state of the brake pedal BP. Here, the “large state” means the driving force transmission capacity selected in the strong creep state as described above.

In the starting clutch, although the driving force transmission capacity in the strong creep state is set to be larger than the driving force transmission capacity in the weak creep state in the starting clutch, the prime mover normally operates when the accelerator pedal is not depressed. Is set to an extent that can transmit the output of or less. Therefore, when the driver steps on the accelerator pedal to increase the driving force and increases the output of the prime mover, it is necessary to further increase the driving force transmission capacity beyond the driving force transmission capacity during strong creep. Here, if the driving force transmission capacity during strong creep is set large enough to transmit the output of the prime mover when the accelerator pedal is fully depressed, the transmission capacity theoretically exceeds the strong creep transmission capacity. Although it is not necessary to further increase (assuming that the engine 1 does not stall and stop), the viewpoint of improving fuel efficiency by minimizing the load of the hydraulic pump that supplies the hydraulic pressure to the starting clutch, and the accelerator pedal that controls the driving force of strong creep This is not practical because the output of the prime mover when not depressed may be set to a level that is not transmitted to the drive wheels 8.8. Therefore, the driving force transmission capacity is set to a value greater than or equal to the state where the brake pedal BP is depressed when the accelerator pedal is depressed.

Making the driving force transmission capacity "greater than or equal to" by depressing the accelerator pedal regardless of the depressed state of the brake pedal BP is necessary for a driver who desires to increase the driving force by depressing the accelerator pedal. It is possible to cope with a driver who is suitable for his / her intention and depresses the accelerator pedal with the right foot and simultaneously depresses the brake pedal BP with the left foot to increase the driving force and then release the brake pedal BP to start.

The above-described driving force transmission capacity control device D
An example of the basic control of the CU is shown in the flowchart of FIG. In this flowchart, the traveling position of the transmission is detected and determined (J1). When the transmission is not at the traveling position, the starting clutch is not connected (the state of zero driving force transmission capacity is maintained). Judgment is made by detecting depression of the accelerator pedal (J2). When the depression is depressed, the driving force transmission capacity is set to "large state or more". On the other hand, when the accelerator pedal is not depressed, the vehicle speed is detected and determined (J3), and if the vehicle speed is not lower than the first predetermined vehicle speed, the driving force transmission capacity is set to "above a large state". And
If the vehicle speed is equal to or lower than the first predetermined vehicle speed, the brake pedal BP
(J4), the driving force transmission capacity is set to a "large state" when it is not depressed, and the driving force transmission capacity is set to a "small state" when it is depressed.

<< Brake Hydraulic Pressure Holding Device >> [Configuration of Brake Hydraulic Pressure Holding Device] As shown in FIG.
The brake fluid is incorporated in the brake fluid pressure passage FP of the hydraulic brake device BK, communicates with the brake fluid pressure passage FP between the master cylinder MC and the wheel cylinder WC, and cuts off the brake fluid pressure passage so that the brake fluid in the wheel cylinder is released. It has a solenoid valve SV that switches to a shut-off position for holding pressure.
The solenoid valve SV is controlled by a control unit CU which is also a control unit of the driving force transmission capacity control unit DCU.

First, the hydraulic brake device BK will be described (see FIG. 3). The brake hydraulic circuit BC of the hydraulic brake device BK includes a master cylinder MC, a wheel cylinder WC, and a brake hydraulic passage FP connecting the master cylinder MC and the wheel cylinder WC. Since the brake plays an extremely important role for safe driving, the hydraulic brake device BK has two independent brake hydraulic circuits (BC (A), BC (B)), and one of the systems has failed. Even at the moment, the rest of the system is designed to provide the minimum braking force.

The main body of the master cylinder MC has a piston M
The CP is inserted and the driver
, The piston MCP is pushed and pressure is applied to the brake fluid in the master cylinder MC, and mechanical force is converted into brake fluid pressure (pressure applied to the brake fluid). When the driver releases his / her foot from the brake pedal BP to release the depression, the piston MCP is driven 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. 3 has two pistons MCP arranged side by side from the viewpoint of fail-safe that two independent brake hydraulic circuits BC are provided.
Tandem type master cylinder MC with the main body divided into two
It is.

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. 3 is of a vacuum (negative pressure) servo type.
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. When the brake fluid pressure of the wheel cylinder WC is higher, it functions as a flow path for returning the brake fluid from the wheel cylinder WC to the master cylinder MC. Since the brake hydraulic circuits BC are provided independently as described above, two independent brake hydraulic passages FP are provided. A brake hydraulic circuit BC constituted by a 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. The brake hydraulic circuit is not of the X-pipe type, but 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.

The wheel cylinder WC is provided for each wheel 8, and the brake fluid pressure generated by the master cylinder MC and transmitted to the wheel cylinder WC through the brake fluid pressure passage FP is applied to a mechanical force (for braking the wheels 8). (Braking force). Wheel cylinder WC
A piston is inserted into the main body of the vehicle, and the piston is pressed by the brake fluid pressure to actuate a brake pad in the case of a disc brake and a brake shoe in the case of a drum brake to actuate a braking force for braking the wheels 8. To produce In addition to the above, a brake fluid pressure control valve for controlling the brake fluid pressure of the front wheel cylinder WC and the brake fluid pressure of the rear wheel cylinder WC is provided as necessary.

Next, the brake fluid pressure holding device RU will be described (see FIG. 3). The brake fluid pressure holding device is a solenoid valve S
V and, if necessary, a throttle D, a check valve CV and a relief valve RV, and are incorporated in a brake fluid pressure passage FP connecting the master cylinder MC and the wheel cylinder WC.

The solenoid valve SV is actuated by an electric signal from the control means CU, shuts off the flow of the brake fluid in the brake fluid pressure passage FP at the shutoff position, and holds the brake fluid pressure applied to the wheel cylinder WC. The flow of the brake fluid in the brake fluid pressure passage FP is permitted at the communication position. Incidentally, the two solenoid valves SV shown in FIG. 3 indicate that they are both in the communicating position. By this solenoid valve SV, even when the driver releases the brake pedal BP when starting uphill, the brake fluid pressure is held in the wheel cylinder WC,
It is possible to prevent the vehicle from leaning backward. Note that the backward movement means that the vehicle travels in a direction opposite to the direction in which the driver tries to advance due to the own weight of the vehicle (downslope).

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.
Either solenoid 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. In addition,
In normal operation, the solenoid valve SV is in the shut-off position because:
A period from when the vehicle stops to when the vehicle starts moving will be described later (under what conditions) when the solenoid valve SV is set to the shut-off position or the communication position.

The throttle D is provided as necessary and is provided with a solenoid valve S
Master cylinder MC regardless of the state of V communication
And the wheel cylinder WC. Especially the solenoid valve SV
Is in the shut-off position, and when the driver releases or depresses the brake pedal BP, the brake fluid trapped in the wheel cylinder WC is gradually released to the master cylinder MC side, and the brake fluid pressure of the wheel cylinder WC is increased. At a predetermined speed. This aperture D
Can be configured by providing a flow control valve in the brake fluid pressure passage FP, or a portion of the brake fluid pressure passage FP that becomes a resistance to fluid (a portion where the cross-sectional area of the flow passage is reduced) May be provided.

If the driver releases or loosens the brake pedal BP due to the presence of the throttle D, even if the solenoid valve SV is in the shut-off position, there is no state where the brake is permanently applied, and the braking force ( Braking force) decreases. That is, the rate of decrease in the brake fluid pressure in the wheel cylinder WC can be made smaller than the rate of decrease in the depression force of the driver's brake pedal BP.
Thus, even after the solenoid valve SV is in the shut-off position, the braking force is sufficiently reduced after a predetermined time, and the vehicle can be started (uphill) by the driving force of the prime mover. On a downhill, the vehicle can be started by its own weight only by releasing or loosening the brake pedal BP without depressing the accelerator pedal.

In the state where the driver depresses the brake pedal BP, as long as the brake fluid pressure of the master cylinder MC is higher than the brake fluid pressure of the wheel cylinder WC, the braking force may not be reduced by the presence of the throttle D. Absent. This is because the throttle D has a function of flowing the brake fluid at a predetermined speed from a higher brake fluid pressure to a lower brake fluid pressure due to a difference (differential pressure) between the brake fluid pressures of the wheel cylinder WC and the master cylinder MC. That is, as long as the driver does not loosen the depression of the brake pedal BP, the brake fluid pressure of the wheel cylinder WC may increase due to the presence of the throttle D, but does not decrease. The throttle D may have a check valve function to prevent the flow of the brake fluid from the master cylinder MC to the wheel cylinder WC.

The speed at which the brake fluid pressure of the wheel cylinder WC is reduced is determined by, for example, moving the vehicle backward from the weak creep state to the strong creep state by releasing the brake pedal BP when the driver releases the brake pedal BP on an uphill or the like. Anything that can be prevented can be used. If the speed of decreasing the brake fluid pressure of the wheel cylinder WC is high,
Even if the solenoid valve SV is in the shut-off position, the brake pedal BP
As soon as the brake pedal is released, the braking force is lost, and the vehicle moves backward on the hill until sufficient driving force is obtained. Conversely, if the speed at which the brake fluid pressure of the wheel cylinder WC is reduced is low, even if the brake pedal BP is depressed, the state in which the brakes work well will continue, so that the vehicle will not recede, but will resist the braking force. Extra time and power are required to secure the driving force, which is not preferable. Incidentally, the vehicle according to the present embodiment performs control to return the solenoid valve SV to the communication position when the vehicle starts to generate a driving force and the depression of the brake pedal BP is released, as described later. When starting by force, there is no problem even if the speed of reducing the brake fluid pressure of the wheel cylinder WC by the throttle D is low.

The speed at which the throttle D reduces the brake fluid pressure of the wheel cylinder WC is determined by the properties of the brake fluid and the type of the throttle D (shape such as cross-sectional area and length of the flow path). In addition, the throttle D is set to the solenoid valve SV or the check valve CV
It may be provided as a single body in combination with the above. The combination can reduce the number of parts and the installation space.

A check valve CV is also provided if necessary. This check valve CV is a brake fluid generated in the master cylinder MC when the solenoid valve SV is in the shut-off position and the driver increases the brake pedal BP. It serves to transmit the pressure to the wheel cylinder WC. Check valve C
V works effectively when the brake fluid pressure generated in the master cylinder MC exceeds the brake fluid pressure of the wheel cylinder WC, and the brake fluid pressure of the wheel cylinder WC is quickly increased in response to an increase in the driver's brake pedal BP. To rise. Incidentally, if the solenoid valve SV once closed is brought into the communication position when the brake fluid pressure of the master cylinder MC becomes higher than the brake fluid pressure of the wheel cylinder WC, the brake pedal BP can be controlled only by the solenoid valve SV. Since it is possible to cope with an increase in the number of steps, there is no need to provide the check valve CV at all.

A relief valve RV is also provided if necessary. This relief valve RV is used when the solenoid valve SV is in the shut-off position and when the driver releases or depresses the brake pedal BP. Wheel cylinder W
The brake fluid trapped in C is quickly released to the master cylinder MC side until a predetermined brake fluid pressure (relief pressure) is reached. The relief valve RV operates when the brake fluid pressure of the wheel cylinder WC is equal to or higher than a predetermined brake fluid pressure and higher than the brake fluid pressure of the master cylinder MC. Thus, even when the solenoid valve SV is in the shut-off position, it is possible to quickly reduce the brake fluid pressure in the wheel cylinder WC more than necessary to the relief pressure. Therefore, "when the driver depresses the brake pedal BP more strongly than necessary when starting the vehicle, it takes time to reduce the brake fluid pressure of the wheel cylinder WC only by the throttle D after the brake pedal BP is released and released. The problem of "undesirable" can be solved by the relief valve RV. Incidentally, in the vehicle according to the present embodiment, the relief valve RV has a meaning when the vehicle does not start due to the start driving force, for example, when the vehicle goes down a slope by its own weight by loosening the brake pedal BP.

The brake switch BSW detects whether or not the brake pedal BP is depressed, and based on the detected value, the control means CU issues an instruction to open or close the solenoid valve SV. By the way, in addition to the solenoid valve SV, the throttle D,
The configuration including the relief valve RV and the check valve CV can be achieved by using a proportional solenoid valve (linear solenoid valve) that can arbitrarily adjust the opening degree of the valve.

[Basic control of brake fluid pressure holding device]
Next, basic control of the brake fluid pressure holding device RU will be described. 1) First, the brake hydraulic pressure holding device RU switches the solenoid valve SV to the shut-off position on condition that the brake pedal BP is depressed at a second vehicle speed or less. The condition "below the second predetermined vehicle speed" is that if the solenoid valve SV is switched to the shutoff position when the vehicle speed is high, the vehicle may not be able to stop at the position desired by the driver, but the vehicle is stopped. This is because if the vehicle speed is extremely low immediately before the vehicle stops, the solenoid valve SV may be in the shut-off position without affecting the driver's operation. "The brake pedal BP is depressed"
This is because the brake fluid pressure is not maintained even when the solenoid valve SV is set to the shut-off position in a situation where the brake pedal BP is not depressed, so that it is meaningless to set the solenoid valve SV to the shut-off position. In addition to the above, if the fact that the driving force transmission capacity is in the “small state” when holding the brake fluid pressure is added to the condition for switching the solenoid valve SV to the shut-off position, the driver strongly applies the brake pedal BP You can stop firmly on the slope to step on. Also, fuel economy can be reduced. The “small state” of the driving force transmission capacity includes a state where the driving force transmission capacity is zero and a state where the engine 1 is stopped.

2) Then, the brake fluid pressure holding device RU
Returns the solenoid valve SV to the communication position on condition that the driving force transmission capacity increases to the "large state" and that the brake pedal BP is released. The condition that “the driving force transmission capacity increases to a large state” means that if the driving force is “a large state”, the driving force in the strong creep state will be applied even if the solenoid valve SV returns to the communicating position and the braking force is lost. Because you can resist it. Here, “increase” is because the drive force transmission capacity may be set to “small state” in order to improve fuel efficiency when the solenoid valve SV is in the shut-off position. In other words, when the driving force transmission capacity is in the “small state”, it is increased to the “large state”, and the driving force in the strong creep state is used to resist the slope. In addition, the condition that "the depression of the brake pedal BP is released" means that the driver is placed on the brake pedal BP while the driver is releasing the depression of the brake pedal BP by the above condition alone. This is to prevent the inconvenience of giving a shock to the driver's foot, and to prevent this. That is,
Under the above conditions alone, when the brake fluid pressure on the wheel cylinder WC side is high, the driving force transmission capacity is “a large state”.
Is reached, the solenoid valve SV returns to the communicating position, and both cylinders WC
This is because the MC is communicated, and the high brake fluid pressure on the wheel cylinder WC side is instantaneously transmitted to the master cylinder MC side, which may give a shock to the driver's foot placed on the brake pedal BP. In particular,
For a driver who depresses the accelerator pedal with the right foot and simultaneously depresses the accelerator pedal with the left foot to increase the driving force and then releases the brake pedal BP to start, the driving force transmission capacity is "large". When the solenoid valve SV is brought into the communicating position when the pressure is changed to the wheel cylinder WC depending on the state of depression of the brake pedal BP and the degree of loosening (difference in brake fluid pressure between the two cylinders MC and WC).
The high brake fluid pressure on the side is instantaneously transmitted to the master cylinder MC side, giving a shock to the driver's foot placed on the brake pedal BP. However, if the condition is satisfied, the depression of the brake pedal BP is released and there is no driver's foot on the brake pedal BP. Even if the driver's foot is on the brake pedal BP, the depression of the brake pedal BP is depressed. Is released, so that there is no further return of the brake pedal BP to the driver side, and no shock is applied to the driver's foot.

<< Specific Vehicle Control >> Next, what kind of control is performed in the vehicle in the present embodiment will be specifically described. [Case where Brake Fluid Pressure is Held] First, a case where the brake fluid pressure is held by the brake fluid pressure holding device RU will be described. FIG. 4 shows that the brake fluid pressure is maintained.
As shown in (a), the driving force of the vehicle is in a weak creep state, and the vehicle speed is 0 km / h. When this condition is satisfied, the solenoid valve SV comes to the shut-off position, and the brake fluid pressure is held in the wheel cylinder WC. Note that the driving force is in a weak creep state (F # WCRON =
The state becomes 1) after the weak creep command (F # WCRP = 1) is issued, but it is assumed that the brake pedal BP is depressed (see FIGS. 2 and 4 (a)). The switching of the creep state is performed by the driving force transmission capacity control unit DCU incorporated in the CVT 3.

I) The condition of "weak creep state"
This is because the driver is required to depress the brake pedal BP sufficiently uphill. That is, in the strong creep state, for example, the driver has a driving force so that the vehicle does not recede even on a slope having an inclination of 5 degrees, so that the driver can stop the vehicle on the slope without depressing the brake pedal BP strongly. Therefore, the driver may depress the brake pedal BP only weakly. In such a case, the solenoid valve SV is set to the shut-off position and the engine 1
If you stop, the vehicle will back down the slope. Here, the "weak creep state" is indicated by the solenoid valve S
Although the condition that V is set to the shut-off position is set as the condition that the electromagnetic valve SV is set to the shut-off position, the basic condition that the weak valve is in the weak creep state, that is, the depression of the brake pedal BP, may be used. .

II) The condition that the vehicle speed is 0 km / h is because the vehicle cannot be stopped at an arbitrary position if the solenoid valve SV is closed during traveling.
In the present embodiment, “the vehicle speed is 0 km / h” corresponds to “the second predetermined vehicle speed”.

I) Conditions under which a weak creep command is issued;
The weak creep command (F_WCRP) is, as shown in FIG. 4A, 1) that the brake fluid pressure holding unit RU is normal, 2) that the brake fluid temperature is equal to or higher than a predetermined value (F_BKT).
O), 3) that the brake pedal BP is depressed and the brake switch BSW is ON (F_BKSW);
4) The vehicle speed is 5 km / h or less (F_VS)
5) Position switch PSW is in D range (F
_POSD), 6) The accelerator pedal is released and the throttle is off (V_TH =
0) is issued when all the conditions are satisfied.
The driving force is set to be in the weak creep state in addition to the reason that the driver strongly depresses the brake pedal BP as described above, and also the reason that fuel efficiency is improved. Hereinafter, the conditions 1) to 6) will be described.

1) The reason why the weak creep command is not issued when the brake fluid pressure holding device RU is not normal is, 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. When the vehicle is released, the braking force is lost at once and the vehicle moves backward on the slope. In this case, by maintaining a strong creep state, backward movement on a slope is prevented, and starting on a slope (starting on a slope) is facilitated.

2) The reason why the weak creep command is not issued when the brake fluid temperature is less than the predetermined value is that when the brake fluid pressure is low, the brake fluid pressure holding device RU is operated to set the solenoid valve SV to the shut-off position, This is because there is a problem that the speed of decrease in the brake fluid pressure of the wheel cylinder WC becomes extremely slow when the depression of the BP is partially relaxed. That is, if the brake pedal BP is only loosened,
The brake switch BSW remains ON, and the solenoid valve SV is in the shut-off position forever. Accordingly, the brake fluid is discharged only through the narrow throttle D. However, since the brake fluid has a high viscosity when the temperature is low, the brake fluid does not flow at a desired speed, so that the brake force is maintained in a strong state forever. This is because they will be left behind. As described above, when the brake fluid temperature is low, the weak creep state is prohibited, the strong creep state is maintained, and backward movement on a slope is prevented. Incidentally, if the strong creep state is maintained, the brake hydraulic pressure holding device RU does not operate, and the solenoid valve SV does not reach the shut-off position. In the case of the brake fluid pressure holding device RU having a configuration in which the throttle D is not provided in the brake fluid pressure circuit BC, for example, the brake fluid pressure holding device RU having a configuration using a proportional solenoid valve capable of changing the opening of the valve is used. In that case, the importance of controlling the temperature of the brake fluid is not very high. Therefore, even when the brake fluid temperature is low to some extent, a weak creep command can be issued.

3) The reason why the weak creep command is not issued when the brake pedal BP is not depressed is that the driver does not want to at least reduce the driving force.

4) When the vehicle speed is 5 km / h or more, the weak creep command is not issued because the driving wheel 8
This is because the reverse drive force from the motor 8 may be transmitted to the engine 1 or the motor 2 to apply the engine brake or cause the motor 2 to perform regenerative power generation. Therefore, the vehicle speed was set to 5 km / h or less. The vehicle speed of 5 km / h or less means "below the first predetermined vehicle speed".

5) Unlike the case where the position switch PSW is in the D range, the weak creep command is not issued when the position switch PSW is in the R range or the L range. This is for facilitating garage entry due to strong creep running.

6) The reason why the weak creep command is not issued when the throttle is not turned off is that the driver wants to increase the driving force by depressing the accelerator pedal.

Whether or not the vehicle is in the weak creep state is determined by the hydraulic pressure command value for the starting clutch. The flag F_WCRPON in the weak creep state continues until the next strong creep state.

II) Automatic engine stop condition: Although it is not directly related to the condition for maintaining the brake fluid pressure, the vehicle in the present embodiment further improves fuel efficiency. Automatically stopped by prime mover automatic stop device. This condition will be described. When all of the following conditions are satisfied, an engine stop command (F_ENG
OFF) is issued, and the engine 1 is automatically stopped (see FIG. 4B).

1) The position switch PSW is in the D range and the mode switch MSW is in the D mode (hereinafter, this state is referred to as "D range D mode"); 1 does not stop automatically. For example, when the position switch PSW is in the P range or the N range, a command to automatically stop the engine 1 is issued and the engine 1
When the vehicle stops automatically, the driver may think that the ignition switch has been turned off and leave the vehicle. When the position switch PSW is in the D range and the mode switch MSW is in the S mode (hereinafter, this state is referred to as “D range S mode”), the engine 1 is not automatically stopped. This is because the driver expects that the vehicle can be started quickly in the D range S mode. Also, the position switch P
The reason why the engine 1 is not automatically stopped when the SW is in the L range or the R range is that it is troublesome if the engine 1 is automatically stopped frequently when entering a garage or the like.

2) The brake pedal BP is depressed and the brake switch BSW is ON; this is to call the driver's attention. Even if the engine 1 is automatically stopped, if the brake switch BSW is ON, the brake pedal BP is depressed and it is considered that there is sufficient braking force to stop on a slope, but even if there is not enough braking force, , 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 moving backward on the slope, the driver can easily increase the brake pedal BP.

3) After the engine is started, the vehicle speed once reaches 5 km / h or more; this is for facilitating putting out and putting in the garage during creep running. This is because it is troublesome if the engine 1 is automatically stopped every time the vehicle 1 is stopped due to a turning operation when the vehicle is put in or out of the garage.

4) The vehicle speed is 0 km / h; if the vehicle is stopped, no driving force is required. 5) The battery capacity is equal to or greater than a predetermined value; this is to prevent the motor 2 from restarting the engine 1 after the engine 1 automatically stops. 6) The electric load must be less than the specified value; this is to ensure the supply of electricity to the load. If the electric load is equal to or less than the predetermined value, there is no problem even if the engine 1 is automatically stopped.

7) The negative pressure in the constant pressure chamber of the master power MP is equal to or higher than a predetermined value; when the engine 1 is stopped with the negative pressure in the constant pressure chamber being small, the negative pressure in the constant pressure chamber is introduced from the intake pipe of the engine 1. Therefore, the negative pressure in the constant-pressure chamber is further reduced, the amplification of the depression force when the brake pedal BP is depressed is reduced, and the effectiveness of the brake is reduced.

8) The accelerator pedal is not depressed. In the state where the accelerator pedal is not depressed (throttle TH [OFF]), the driver does not want to increase the driving force, and automatically stops the engine 1. No problem.

9) The CVT 3 is in a weak creep state (the driving force transmission capacity is in a small state);
This is to prevent the vehicle from moving backward even after the automatic stop. That is, when the engine 1 is started, backward movement on a slope is prevented by the sum of the braking force and the creep force. For this reason, in the strong creep state, the driver may depress the brake pedal BP more or less and may depress it only weakly. Therefore, the engine 1 is automatically stopped after the weak creep state.

10) The ratio of CVT3 is low;
If the ratio (pulley ratio) of CVT3 is not low,
The automatic stop of the engine 1 is not performed because there is a case where the vehicle cannot start smoothly. Therefore, CV for smooth start
When the ratio of T3 is low, the engine 1 is automatically stopped.

11) The water temperature of the engine 1 is equal to or higher than a predetermined value; this is because the automatic stop / 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 be restarted in a cold region, so the automatic stop of the engine 1 is not performed.

12) The oil temperature of the CVT 3 is equal to or higher than a predetermined value. If the oil temperature of the CVT 3 is low, the actual rise of the hydraulic pressure of the starting clutch is delayed, and the engine 1 starts to be in a strong creep state. It takes a long time to stop the engine 1 because the vehicle may move backward on a slope.

13) The temperature of the brake fluid must be equal to or higher than a predetermined value; if the temperature of the brake fluid is low, the fluid resistance at the throttle D increases, causing unnecessary brake dragging. Therefore, the brake hydraulic pressure holding device RU is not operated. Therefore, the stop of the engine 1 and the weak creep state are prohibited, and the backward movement on the slope is prevented by the strong creep. In the case of the brake fluid pressure holding device RU having a configuration in which the throttle D is not provided in the brake fluid pressure circuit BC, for example, the fluid pressure holding device RU having a configuration using a proportional solenoid valve LSV capable of changing the opening of the valve is used. In that case, the temperature control of the brake fluid is not so important.

14) The brake fluid pressure holding device RU is normal; if the brake fluid pressure holding device RU is abnormal, the brake fluid pressure may not be able to be maintained. So that the vehicle does not back up on a slope. Therefore, when there is an abnormality in the brake fluid pressure holding device RU, the automatic stop of the engine 1 is not performed. On the other hand, if the brake fluid pressure holding device RU is normal, there is no problem even if the engine 1 is automatically stopped.

[When brake fluid pressure is released]
Once the solenoid valve SV is in the shut-off position, as shown in FIG. 5A, I) after the brake pedal BP is depressed and released,
If the predetermined delay time has elapsed, II) Brake pedal B
When the stepping on P is released and the driving force is in a strong creep state, III) When the vehicle speed is 5 km / h or more, the vehicle returns to the communication position when any of the conditions is satisfied, and the brake fluid pressure holding device The holding of the brake fluid pressure by the RU is released. The condition “II” means that “the driving force capacity of the starting clutch has increased to a large state and the depression of the brake pedal BP has been released”.

I) The delay time is determined when the brake pedal BP is released (when the brake switch BSW is
FF). The delay time is about 2 to 3 seconds, and the solenoid valve SV is returned to the communication position as a fail-and-safe action to eliminate brake dragging.

II) Returning the solenoid valve SV to the communicating position when the brake pedal BP is released and the driving force is in the strong creep state is different from the weak creep state in which the driving force is zero or little, unlike the strong creep state. This is because, for example, the vehicle is provided with a driving force capable of stopping the vehicle against a hill of 5 degrees, so that the vehicle is prevented from moving backward even if the holding of the brake fluid pressure is released. The strong creep state is set after the strong creep command (F_SCRP) is issued, but the strong creep command is issued when the brake pedal BP is released in the D range.
Here, the condition that the depression of the brake pedal BP is released is a condition that the solenoid valve SV is returned to the communication position when a strong creep state occurs while the depression of the brake pedal BP is released. When the holding of the brake fluid pressure is released by the
It may cause shock to the driver's feet placed on the vehicle.

III) When the vehicle speed becomes 5 km / h or more, the solenoid valve SV is brought into the communicating position by a fail-and-safe action for eliminating unnecessary brake dragging.

[Automatic Engine Start Condition] After the engine 1 is automatically stopped, the engine 1 is automatically started when any of the following conditions is satisfied. This condition will be described (see FIG. 5B). ).

1) D range D mode and release of brake pedal BP released; it is determined that the driver's start operation has been started, so engine 1 starts automatically.

2) When the mode is switched to the D range S mode: When the engine 1 is automatically stopped in the D range D mode and then switched to the D range S mode, the engine 1 automatically starts. This is because the driver expects a quick start in the D range S mode, and automatically starts the engine 1 without waiting for the release of the brake pedal BP.

3) When the accelerator pedal is depressed (throttle TH [ON]): This is because the driver expects the driving force of the engine 1.

4) When the range is switched to the P range, N range, L range and R range: When the engine 1 is automatically stopped in the D range D mode and then switched to the P range or the like, the engine 1 automatically starts. If the engine 1 does not start automatically when switching to the P range or the N range, the driver may think that the ignition switch has been turned off or think that there is no need to turn off the ignition switch, and will leave the vehicle as it is. This is because it is not preferable from the viewpoint of fail and safe. In order to prevent such a situation, the engine 1 is automatically started. When the engine is switched to the L range or the R range, the engine 1
Is automatically started because it is determined that the driver intends to start.

5) When the battery capacity is equal to or less than a predetermined value;
Is not automatically stopped, the battery capacity may be reduced even after the engine 1 is automatically stopped once. In this case, the engine 1 is automatically started for the purpose of charging the battery. 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.

6) When the electric load exceeds a predetermined value;
For example, when an electric load such as lighting is operating, the battery capacity is rapidly reduced, and the engine 1 cannot be automatically started. 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.

7) When the negative pressure of the master power drops below a predetermined value: When the negative pressure of the master power MP decreases, the braking force of the brake decreases, and the engine 1 is restarted to secure this.

8) When the brake fluid pressure holding device is out of order; When the solenoid valve SV or the drive circuit of the solenoid valve is out of order, the engine 1 is automatically started to create a strong creep state. After the automatic stop of the engine 1, if a failure is detected in the brake fluid pressure holding device RU including the drive circuit of the solenoid valve, the brake fluid pressure may be held when the brake pedal BP is released when starting. In some cases, the engine 1 is automatically started when a failure is detected in order to set a strong creep state. That is, the vehicle is prevented from moving backward in the strong creep state, and the vehicle can be easily started uphill.

<< Time Chart of Control >> Next, how the vehicle according to the present embodiment is controlled while traveling will be described with reference to FIGS. 6 to 9. FIG. In addition,
FIG. 6 shows a time chart of the control when the accelerator pedal and the brake pedal BP are not simultaneously depressed, and FIGS. 7 to 9 show the control time when the accelerator pedal and the brake pedal BP are depressed simultaneously. The chart is shown.

[Control Time Chart 1 (No Simultaneous Depression)] This is a control time chart when the driver does not simultaneously depress the accelerator pedal and the brake pedal BP. The position switch PSW and the mode switch MSW of this vehicle are not changed in the D mode D range (running position). Further, the brake fluid pressure holding device RU has a configuration provided with a throttle D and a relief valve RV. Here, the upper part of FIG. 6 is a time chart showing the increase and decrease of the driving force and the braking force of the vehicle in time series. In the drawing, a thick line indicates the driving force, and a thin line indicates the braking force. The middle diagram in FIG. 6 is a diagram showing the depression state of the accelerator pedal. The lower part of FIG. 6 is a time chart showing a state of communication and cutoff of the solenoid valve SV. The accelerator pedal is depressed when TH [ON] in FIG. 6, and the accelerator pedal is released when TH [OFF].

First, in FIG. 6, when the driver depresses the brake pedal BP when the vehicle is running (the brake SW [O
N]) The braking force increases. When the driver depresses the brake pedal BP for deceleration, the driver releases the depression of the accelerator pedal (TH [OFF]), so that the driving force is attenuated and eventually enters a strong creep state (normal idling). Then, when the brake pedal BP is continuously depressed and the vehicle speed becomes 5 km / h or less, a weak creep command (F_WCRP) is issued, the vehicle enters a weak creep state (F_WCRPON), and the driving force further weakens.

When the vehicle speed reaches 0 km / h, the solenoid valve SV
Is switched to the cutoff position, and the engine 1 is automatically stopped (F_ENGOFF), and the driving force is lost. On this occasion,
Since the solenoid valve SV is in the shut-off position, the wheel cylinder W
C holds the brake fluid pressure. Further, since the engine 1 is stopped after passing through the weak creep state, the driver is required to make the brake pedal BP strong enough to prevent the vehicle from moving backward even on a slope.
Is stepping on. Therefore, even if the engine 1 is automatically stopped on a slope, the vehicle does not move backward (reverse restraining force). Even if you are going backwards, the brake pedal BP
By slightly increasing the number of steps, backward movement is prevented. Since the driver is in a state where the brake pedal BP is depressed (a state where the foot is put on the brake pedal BP), the driver can easily increase the brake pedal BP without panic. The reason why the engine 1 is automatically stopped is to improve fuel efficiency and eliminate generation of exhaust gas. The conditions under which the driving force enters the weak creep state, the conditions under which the solenoid valve SV is brought into the shut-off position, and the conditions under which the engine 1 is automatically stopped are as already described with reference to FIG.

Next, the driver releases the brake pedal BP in preparation for the restart. The driver sets the brake pedal B higher than the relief pressure that is the set pressure of the relief valve RV.
P, the relief valve RV is released by releasing the brake pedal BP as shown in the upper diagram of FIG.
Is activated to reduce the braking force to the relief pressure in a short time. With this relief valve RV, even when the driver depresses the brake pedal BP more strongly than necessary, it is possible to quickly start uphill.

When the brake pedal BP is completely released (brake SW [OFF]), an engine automatic start command (F_ENGON) is issued, and after a time lag due to signal communication and a delay in the mechanical system, the engine 1 automatically operates. Start. Then, the driving force increases and a strong creep state occurs (F_SCRPON). The time from when the brake pedal BP is released (the brake switch BSW is turned off) to when the strong creep state is reached is about 0.5.
Seconds. During this time, since the solenoid valve SV is still in the shut-off position, the brake fluid can move to the master cylinder MC side only through the small throttle D, so that the braking force is reduced only gradually and the vehicle is prevented from moving backward. You.

Then, in the strong creep state (F_SCRPO
In the case of N), a driving force capable of resisting a slope is generated, so that the braking force does not hinder the start of the vehicle, and in order to eliminate unnecessary dragging of the brake,
The solenoid valve SV at the shut-off position is returned to the communication position, and the brake fluid pressure of the wheel cylinder WC is reduced at a stretch to eliminate the braking force. Thereafter, the driving force increases by further depressing the accelerator pedal, and the vehicle accelerates.
The conditions under which the driving force is in the strong creep state and the conditions under which the solenoid valve SV is in the communicating state are as already described with reference to FIG.

By the way, in the line indicating the braking force in the upper diagram of FIG. 6, a virtual line which falls obliquely downward to the right from the “relief pressure” portion indicates a case where the brake fluid pressure is not maintained,
In this case, the braking force is reduced and disappears without being delayed by the reduction in the depressing force of the brake pedal BP, so that it is not easy to start uphill. This imaginary line indicates the return status of the brake pedal BP. Next, on the line indicating the braking force in the upper diagram of FIG. 6, the time when the strong creep state is achieved (this is also the time when the solenoid valve SV is in the communicating state).
The phantom line that gradually decreases from right to the lower right is the solenoid valve S
4 shows a state of reduction in braking force when V is not in a communicating state. When the braking force is reduced as shown by the imaginary line, the brake is dragged, which is not preferable.

As described above, when the accelerator pedal and the brake pedal BP are not depressed at the same time, even if the solenoid valve SV is returned to the communication position when the driving force is in a strong creep state, the brake pedal BP returns completely. (The driver's foot is not on the brake pedal BP), and no shock is applied to the driver's foot even if the two cylinders WC and MC are connected.

[Control Time Chart 2 (Simultaneous Depression)] This is a control time chart when the driver simultaneously depresses the accelerator pedal and the brake pedal BP. At this time, it does not matter whether the driver uses only one foot (heel & toe) or both feet. The position switch PS of this vehicle
W and the mode switch MSW are not changed in the D mode D range (running position). Further, the brake fluid pressure holding device RU has a configuration provided with a throttle D relief valve RV (the same configuration as the control time chart 1). Here, the upper part of FIG. 7 is a time chart showing the increase and decrease of the driving force and the braking force of the vehicle in time series. In the drawing, a thick line indicates the driving force, and a thin line indicates the braking force. The middle diagram in FIG. 7 is a diagram showing the depression state of the accelerator pedal. The lower part of FIG. 7 is a time chart showing the state of communication and cutoff of the solenoid valve SV. The accelerator pedal is depressed when TH [ON] in FIG. 7, and the accelerator pedal is released when TH [OFF].

[0111] Until the relief valve RV operates, the operation is the same as that in the "time chart 1 of control", and the description thereof will be omitted. The brake fluid pressure in the wheel cylinder WC is reduced to the relief pressure by operating the relief valve RV, but thereafter, since the solenoid valve SV is in the shut-off position, the brake fluid pressure in the wheel cylinder WC, that is, the braking force is reduced by the throttle D Only gradually decreases. On the other hand, the driver simultaneously depresses the brake pedal BP and the accelerator pedal, and starts at a stretch after increasing the driving force, so that the brake pedal BP is not completely released. Alternatively, after the brake pedal BP is completely released, the brake pedal BP is again released before the strong creep state is reached.
Step on Therefore, the brake switch BSW is ON
Remains. On the other hand, when the accelerator pedal is depressed (TH [ON]), an automatic start command for the engine 1 is issued (F_ENGON), the engine 1 is automatically started, and the driving force immediately becomes a strong creep state (F_SCRP).
ON). Here, when the solenoid valve SV is returned to the communication position at the time when the strong creep state is achieved as in the related art, if the driver does not strongly depress the brake pedal BP, the brake fluid pressure on the wheel cylinder WC side becomes larger. If high,
The brake fluid pressure on the wheel cylinder WC side where the brake fluid pressure is high is transmitted to the master cylinder MC side at once, and the shock due to the brake fluid pressure difference corresponding to the brake force difference as shown by "A" in the upper part of FIG. Will give to the feet of the driver that is on top.

However, if control is performed to return the solenoid valve SV to the communicating position at the time when the brake pedal BP is released (brake SW [OFF]), no shock is applied to the driver's feet. That is, at this time, the driver's foot is not put on the brake pedal BP, or even if it is put on, the brake pedal BP does not return further.

Incidentally, in the line indicating the braking force in the upper part of FIG. 7, the imaginary line which goes down from the “relief pressure” part to the lower right and goes into a horizontal state indicates the operating condition of the brake pedal BP of the driver. This imaginary line is also obtained by replacing the brake fluid pressure in the master cylinder MC with the braking force. In the line indicating the braking force in the upper diagram of FIG. 7, the imaginary line that gradually lowers diagonally to the lower right from the portion where the solenoid valve SV is in the communicating position is the brake when the solenoid valve SV is not in the communicating position. This shows the force reduction status. When the braking force is reduced as shown by the imaginary line, the brake is dragged, which is not preferable. "A" in the upper part of FIG. 7 indicates a brake pressure difference between the brake fluid pressure held in the wheel cylinder WC at the time of the strong creep state and the brake fluid pressure in the master cylinder MC at that time. This is represented by a force difference (see FIGS. 8 and 9).
The same).

[Control Time Chart 3 (with Simultaneous Depression)] Similar to “Control Time Chart 2”, this is a control time chart when the driver simultaneously depresses the accelerator pedal and the brake pedal BP. At this time, it does not matter whether the driver uses only one foot (heel & toe) or both feet.
The position switch PSW and the mode switch MSW of this vehicle are not changed in the D mode D range (running position). However, the brake fluid pressure holding device R
U has a configuration in which the throttle D is provided but the relief valve RV is not provided. Here, the upper part of FIG. 8 is a time chart showing the increase and decrease of the driving force and the braking force of the vehicle in time series. In the drawing, a thick line indicates the driving force, and a thin line indicates the braking force. The middle diagram in FIG. 8 is a diagram showing the depression state of the accelerator pedal. The lower part of FIG. 8 is a time chart showing the state of communication and cutoff of the solenoid valve SV. Note that T in FIG.
When H [ON], the accelerator pedal is depressed and T
When H [OFF], the accelerator pedal is released.

Until the depression of the brake pedal BP is started to be released, it is the same as the “control time chart 1” and the “control time chart 2”, so the description is omitted. Even after the brake pedal BP starts to be depressed, the solenoid valve SV is in the shut-off position, so that the brake fluid pressure in the wheel cylinder WC, that is, the braking force, is only gradually reduced by the throttle D. On the other hand, the driver is the brake pedal BP
Brake pedal B in order to simultaneously depress the accelerator pedal and the accelerator pedal to increase the driving force and start at once.
The stepping on P is not completely released. Alternatively, after completely depressing the brake pedal BP, the brake pedal BP is depressed again before the strong creep state occurs.
Therefore, the brake switch BSW remains ON. On the other hand, the engine 1 is depressed by the accelerator pedal (TH
[ON]), an automatic start command of the engine 1 is issued (F_ENGON), the engine 1 is automatically started, and the driving force immediately becomes a strong creep state (F_SCRPON). Here, when the solenoid valve SV is returned to the communication position at the time when the strong creep state is achieved as in the related art, the driver does not strongly depress the brake pedal BP, and the brake fluid pressure on the wheel cylinder WC side is smaller. When the brake fluid pressure is high, the brake fluid pressure on the wheel cylinder WC side where the brake fluid pressure is high is transmitted to the master cylinder MC side at a stretch, and "A" is shown in the upper diagram of FIG.
As a result, a shock due to a brake fluid pressure difference corresponding to the brake force difference is applied to the driver's foot mounted on the brake pedal BP. It should be noted that “A” in “Control Time Chart 3” is larger than “A” in “Control Time Chart 2” by the absence of the relief valve RV, and that “A” of the driver placed on the brake pedal BP The shock given to the foot also increases.

However, if control is performed to return the solenoid valve SV to the communication position when the brake pedal BP is released (brake SW [OFF]), no shock is applied to the driver's feet. That is, at this time, the driver's foot is not put on the brake pedal BP, or even if it is put on, the brake pedal BP does not return further. As described above, even in the configuration in which the relief valve RV is not provided, the vehicle can be started after increasing the driving force without giving a shock to the driver's foot, as in the case of the “control time chart 2”.

Incidentally, in the line indicating the braking force in the upper diagram of FIG. 8, "the brake pedal starts to be depressed"
An imaginary line that goes down diagonally to the right from the portion and becomes a horizontal state indicates the operation status of the brake pedal BP by the driver. This imaginary line is also obtained by replacing the brake fluid pressure in the master cylinder MC with the braking force.

[Control Time Chart 4 (with Simultaneous Depression)] Similar to “Control Time Chart 2” and “Control Time Chart 3”, when the driver simultaneously depresses the accelerator pedal and the brake pedal BP. 6 is a time chart of the control of FIG. At this time, whether the driver uses only one foot (heel & toe),
It does not matter whether you use both feet. The position switch PSW and the mode switch MSW of this vehicle are not changed in the D mode D range (running position). The brake fluid pressure holding device RU of this vehicle has a configuration provided with a throttle D and a relief valve RV. This vehicle does not automatically stop the engine 1 when stopped. Here, the upper part of FIG. 9 is a time chart showing the increase and decrease of the driving force and the braking force of the vehicle in time series. In the drawing, a thick line indicates the driving force, and a thin line indicates the braking force. The middle diagram in FIG. 9 is a diagram illustrating the depression state of the accelerator pedal. The lower part of FIG. 9 is a time chart showing a state of communication and cutoff of the solenoid valve SV. The accelerator pedal is depressed when TH [ON] in FIG. 9, and the accelerator pedal is released when TH [OFF].

Until the vehicle stops, it is the same as the “control time chart 1” to the “control time chart 3”, and the description is omitted. Since the vehicle in the “time chart 4 of control” does not automatically stop the engine 1 even when the vehicle stops, the driving force maintains the weak creep state even during the stop. Since there is almost no driving force in the weak creep state, the backward movement of the vehicle on the slope is prevented by the braking force generated when the driver depresses the brake pedal BP (retraction suppressing force). Then, the driver starts to release the depression of the brake pedal BP of the vehicle. Then the relief valve RV
Operates to reduce the brake fluid pressure in the wheel cylinder WC to the relief pressure. However, since the solenoid valve SV is in the shut-off position, the brake fluid pressure in the wheel cylinder WC, that is, the braking force, is gradually reduced by the throttle D. It only decreases. On the other hand, the driver simultaneously depresses the brake pedal BP and the accelerator pedal, and increases the driving force before starting at a stretch.
Do not completely release the steps. Alternatively, after completely depressing the brake pedal BP, the brake pedal BP is depressed again before the strong creep state occurs. Therefore, the brake switch BSW remains ON. On the other hand, the engine 1 is depressed by the accelerator pedal (TH
[ON]), a strong creep command (F_SCRP) is issued, and the driving force immediately enters a strong creep state (F_SC).
RPON). Here, when the solenoid valve SV is returned to the communication position at the time when the strong creep state is achieved as in the related art, the driver does not strongly depress the brake pedal BP, and the brake fluid pressure on the wheel cylinder WC side is smaller. When the brake fluid pressure is high, the brake fluid pressure on the wheel cylinder WC side with a high brake fluid pressure is transmitted to the master cylinder MC side at a stretch, and FIG.
The shock due to the brake fluid pressure difference corresponding to the brake force difference as indicated by “A” in the upper diagram is applied to the driver's foot mounted on the brake pedal BP.

However, if control is performed to return the solenoid valve SV to the communication position when the brake pedal BP is released (brake SW [OFF]), no shock is applied to the driver's feet. That is, at this time, the driver's foot is not put on the brake pedal BP, or even if it is put on, the brake pedal BP does not return further. As described above, even in the configuration in which the engine 1 is not automatically stopped, as in the case of the “control time chart 2” and the “control time chart 3”, the driving force is increased without giving a shock to the driver's feet. You can launch.

By the way, in the line indicating the braking force in the upper part of FIG. 9, the imaginary line which goes down from the “relief pressure” part to the lower right and goes into a horizontal state indicates the operation status of the driver's brake pedal BP. This imaginary line is also obtained by replacing the brake fluid pressure in the master cylinder MC with the braking force.

As described above, the present invention is not necessarily limited to the above embodiment, and achieves the object of the present invention.
The present invention can be appropriately changed and implemented within a range having the effects of the present invention.

[0123]

As described above, even if the accelerator pedal is depressed and the driving force transmission capacity of the starting clutch increases from "small" to "large" or more, the depression of the brake pedal BP must be released. If the accelerator pedal is depressed, the depression of the brake pedal BP is slightly relaxed, and the driving force transmission capacity of the starting clutch is increased to a "large state". Even if the brake fluid pressure generated from the master cylinder MC is lower than the brake fluid pressure retained in the wheel cylinder WC, the high fluid pressure retained in the wheel cylinder WC is transmitted to the master cylinder MC. There is no. Therefore, when the vehicle stops, only the brake pedal BP is depressed with the left foot, the brake pedal BP is slightly depressed, the accelerator pedal is depressed with the right foot, and the brake pedal BP and the accelerator pedal are depressed simultaneously. In this case, the above-mentioned problem that a shock may be applied to the left foot of the driver depressing the brake pedal BP is solved. This is the same in the case of so-called heel & toe in which both the brake pedal BP and the accelerator pedal are depressed with one foot. After the brake pedal BP and the accelerator pedal are simultaneously depressed, the solenoid valve SV is returned to the communication position when the depression of the brake pedal BP is released. Is not already on the brake pedal BP, or the brake pedal BP is completely returned even if it is on the brake pedal BP. Therefore, when the solenoid valve is returned to the communication position, it is held in the wheel cylinder WC. Even if the high brake fluid pressure is instantaneously transmitted to the master cylinder MC side, no shock is applied to the driver's feet.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a system configuration of a vehicle with a brake fluid pressure holding device according to an embodiment.

FIG. 2 is a flowchart illustrating an example of basic control in a driving force transmission capacity control device.

FIG. 3 is a diagram illustrating a configuration example of a brake fluid pressure holding device.

FIG. 4 is a diagram illustrating control when the vehicle with the brake fluid pressure holding device according to the present embodiment is stopped. (A)
Shows logic for setting the solenoid valve to the shut-off position, and (b) shows logic for automatically stopping the engine.

FIG. 5 is a diagram illustrating control when the vehicle with the brake fluid pressure holding device according to the present embodiment starts. (A)
Shows logic for setting the solenoid valve to the communication position, and (b) shows logic for automatically starting the engine.

FIG. 6 is a time chart of control during traveling of the vehicle with the brake fluid pressure holding device according to the present embodiment, in which depression of an accelerator pedal and depression of a brake pedal are not performed simultaneously. The upper diagram shows the vehicle deceleration → stop →
Changes in driving force and braking force along the time series of starting are shown. The middle diagram shows the depression state of the accelerator pedal, and the lower diagram shows the position of the solenoid valve.

FIG. 7 is a time chart of control corresponding to FIG. 6 in a case where depression of an accelerator pedal and depression of a brake pedal are performed simultaneously.

8 is a time chart of control corresponding to FIG. 7 when a relief valve is not provided.

FIG. 9 is a control time chart corresponding to FIG. 7 when the engine is not automatically stopped when the vehicle stops.

[Explanation of symbols]

 DCU Driving force transmission capacity control unit RU Brake hydraulic pressure holding device SV… Solenoid valve FP Brake hydraulic pressure passage BP Brake pedal MC Master cylinder WC Wheel cylinder CU Control means

Continuation of the front page (56) References JP-A-9-202159 (JP, A) JP-A-1-208241 (JP, A) JP-A-60-128051 (JP, A) JP-A-60-128052 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B60T 7/12

Claims (1)

(57) [Claims] (A) When a traveling position is selected in a transmission of a vehicle at a vehicle speed equal to or lower than a first predetermined vehicle speed, and when an accelerator pedal is depressed and released, a driving force of a starting clutch according to a depressed state of a brake pedal. The transmission capacity is switched between large and small states.When the brake pedal is depressed, the driving force transmission capacity of the starting clutch is reduced, and the driving force transmission capacity of the starting clutch is increased. In addition, the driving force transmitted from the prime mover to the driving wheels is reduced, and when the accelerator pedal is depressed, the driving force transmission capacity of the starting clutch is set to be greater than the large state regardless of the depressed state of the brake pedal. (B) a brake fluid pressure passage between a master cylinder and a wheel cylinder; A solenoid valve is provided for switching between a blocking position for interrupting the communication of the brake fluid pressure to maintain the brake fluid pressure in the wheel cylinder and a communication position for permitting the communication of the brake fluid pressure passage. with switching the electromagnetic valve to the blocking position on condition that they are depressed, the vehicle
Brake pedal and accelerator pedal simultaneously
If the pedal is depressed, the brake that returns the solenoid valve to the communication position on the condition that the driving force transmission capacity of the starting clutch increases from the simultaneously depressed state to the above- described large state and the depression of the brake pedal is released. A vehicle with a brake fluid pressure holding device, comprising: a fluid pressure holding device.