JP2006083830A - Engine control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine control device for improving fuel consumption by reducing the frequency of restarting an engine during idling stop. <P>SOLUTION: A FI/MGECU constituting a motor stopping device stops the engine depending on the condition of footing a brake pedal when a vehicle speed is a preset value or smaller, and it starts the engine when the negative pressure of at least master power is smaller than a preset threshold value. The FI/MGECU determines whether the stop position of a vehicle is flat or not in accordance with front and rear acceleration sensors. When determining that it is flat, it sets the preset threshold value to be smaller than that when it is not flat. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an engine control device capable of automatically stopping an engine and automatically restarting the stopped engine.

  2. Description of the Related Art In recent years, there has been known a technique (so-called idling stop) that improves fuel consumption by automatically stopping an engine when a vehicle is stopped. Such technology is used in various types of vehicles, but in vehicles equipped with a brake booster that generates a negative pressure by driving the engine and obtains a braking force, after the engine is stopped, the negative pressure in the brake booster is reduced. There is an event in which the pressure gradually decreases (negative pressure gradually approaches atmospheric pressure). When the negative pressure in the brake booster (hereinafter also referred to as “booster negative pressure”) decreases to a predetermined value due to the occurrence of such an event, the driver is required to depress the brake pedal more than usual. Since a large force is required, for example, when the vehicle is stopped on an uphill, there is a problem that the driver feels uncomfortable with the brake operation.

  For this reason, conventionally, there is a technology for restarting the engine when the booster negative pressure detected by the pressure sensor falls below a predetermined threshold after the engine is stopped (for example, for example) (for example, , See Patent Document 1). According to this technique, the booster negative pressure can always be maintained at the optimum negative pressure, and the brake operation does not feel uncomfortable.

Japanese Unexamined Patent Publication No. 2003-13768 (paragraph 0074, FIG. 3)

  By the way, in the above-described conventional technology, it is necessary to set the threshold value of the booster negative pressure for restarting the engine to a value that is somewhat higher in consideration of any road surface (for example, a sloping slope). In other words, a stronger braking force (higher booster negative pressure) is required on slopes with higher slopes than on flat ground, so the booster negative pressure threshold for restarting the engine is set to a higher value that matches the harder slopes of the conditions. There is a need to.

  However, if the booster negative pressure threshold is set to a high value according to the slope as described above, the booster can be restarted unnecessarily even on a flat ground where even a small booster negative pressure can stop the vehicle without discomfort. Since the negative pressure is increased, the frequency of engine restart is increased, and fuel is wasted correspondingly.

  Therefore, an object of the present invention is to provide an engine control device capable of improving fuel consumption by reducing the frequency of engine restart during idling stop.

  The invention according to claim 1 of the present invention that solves the above-mentioned problems includes a brake booster that generates a negative pressure by driving the engine to increase a braking force, an engine stop unit that stops the engine, and the engine. An engine stop instructing unit that is mounted on a vehicle having an engine starting means for starting and instructs the engine stopping means to stop the engine according to a depression state of a brake pedal when the vehicle speed is equal to or lower than a predetermined value; An engine control device comprising: an engine start instruction unit that instructs the engine start means to start the engine when at least a negative pressure of the brake booster becomes smaller than a predetermined threshold value. Includes an inclination determination means for determining whether or not the stop position of the vehicle is flat, and the engine start instruction unit If the determination of the determination means is flat, characterized in that even if not more flat land that is configured to reduce the predetermined threshold.

  Here, “the negative pressure is smaller than a predetermined threshold” means that the absolute value of the difference between the measured negative pressure in the brake booster and the atmospheric pressure is smaller than the absolute value of the difference between the threshold and the atmospheric pressure. It means to become. In addition, the “flat ground” includes not only a completely horizontal ground but also a gentle slope that falls within a predetermined small angle range.

  According to the first aspect of the present invention, when the vehicle is stopped on a flat ground, the negative pressure threshold of the brake booster, which is the engine starting condition, is smaller than when the vehicle is stopped on a non-flat ground. Thus, it takes time for the negative pressure to drop to the reduced threshold value, and the idling stop time can be lengthened accordingly. Therefore, the frequency of engine restart during idling stop can be reduced, and fuel consumption can be improved.

  The invention according to claim 2 is the engine control device according to claim 1, wherein when the stop position of the vehicle is a slope, the inclination determination means calculates an inclination of the engine, and the engine The start instructing unit is configured to decrease the predetermined threshold as the slope is small.

  According to the second aspect of the present invention, a large threshold value is set on a steep slope and a small threshold value is set on a gentle slope. Therefore, the engine is quickly restarted on a steep slope and a high braking force (negative pressure) is set. Can be maintained, and idling stops can be made longer on gentle slopes. In other words, it is possible to secure an appropriate braking force according to the slope of the slope, and to improve the fuel consumption by taking a long time until the engine is restarted when the slope requires only a small braking force. be able to.

  A third aspect of the present invention is the engine control apparatus according to the first or second aspect, wherein the inclination determining means includes a longitudinal acceleration sensor, a vehicle height sensor, navigation information, or a fuel tank level sensor. It is characterized by providing.

  According to the third aspect of the present invention, since the slope of the slope can be detected satisfactorily by, for example, a longitudinal acceleration sensor used in other applications, it is not necessary to provide a new sensor for detecting the slope. The cost can be reduced accordingly.

  The invention according to claim 4 is the engine control device according to any one of claims 1 to 3, wherein the engine control device is configured such that the engine is idling and the vehicle speed is high. When the brake pedal is depressed under a condition that is less than or equal to a predetermined value, the creep driving force is switched to a preset small state, and when the brake pedal depression is released under the condition, the creep It is mounted on a vehicle that further includes a driving force control device that switches the driving force to a preset large state.

  Here, “creep” refers to a vehicle that is equipped with an automatic transmission, and when the travel range such as the D range or the R range is selected, even if the accelerator pedal is not depressed (the engine is idling). To move slowly.

  According to the fourth aspect of the present invention, when the engine is idling and the vehicle speed is equal to or lower than the predetermined value, if the brake pedal is depressed, the creep driving force is switched to a small state. At the same time, fuel consumption can be reduced. Further, when the depression of the brake pedal is released from this state, the creep driving force is switched to a large state, so that the vehicle can be smoothly restarted by this large driving force.

  A fifth aspect of the present invention is the engine control device according to any one of the first to third aspects, wherein the brake pedal is depressed when the vehicle is stopped. The engine is stopped on the condition that the driving force is in the preset small state, and the stopped engine is started on the condition that the depression of the brake pedal is released.

  According to the invention described in claim 5, since the engine is stopped in a state where the vehicle is stopped and the brake pedal is depressed, the idling stop can be satisfactorily performed without lowering the vehicle even on a slope. it can. Further, when the brake pedal is released from this state, the engine is started, so that the vehicle can be restarted satisfactorily.

  According to the first aspect of the present invention, when the vehicle is stopped on a flat ground, the idling stop time is reduced because the threshold value of the negative pressure of the brake booster is smaller than when the vehicle is stopped on a non-flat ground. Since it becomes longer, the frequency of restarting the engine during idling stop can be reduced, and fuel consumption can be improved.

  According to the second aspect of the present invention, the negative pressure threshold decreases as the slope of the slope decreases, so that an appropriate braking force can be secured according to the slope of the slope and a small braking force is sufficient. In the case of the inclination, it is possible to improve the fuel consumption by taking a long time until the engine is restarted.

  According to the third aspect of the present invention, since the slope of the slope can be detected satisfactorily by, for example, a longitudinal acceleration sensor used in other applications, it is not necessary to provide a new sensor for detecting the slope. The cost can be reduced accordingly.

  According to the invention described in claim 4, since the driving force of the creep can be switched between a small state and a large state according to the depression state of the brake pedal under a predetermined condition, the braking effectiveness and the fuel consumption can be improved. In addition, the vehicle can be restarted well.

  According to the invention described in claim 5, since the engine is stopped in a state where the vehicle is stopped and the brake pedal is depressed, the idling stop can be satisfactorily performed without lowering the vehicle even on a slope. it can. Further, when the brake pedal is released from this state, the engine is started, so that the vehicle can be restarted satisfactorily.

Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
The vehicle according to the present embodiment includes a prime mover stop device (engine control device) for mainly performing automatic stop or automatic start of the engine, and a brake that keeps the brake force applied to the vehicle after the driver releases the brake operation. A force holding device and a driving force control device that switches the creep driving force between a large state and a small state according to the depression state of the brake pedal when the engine is idling and below a predetermined vehicle speed are mainly provided.

  Here, the features of the present invention will be briefly described first. When idling stop is performed, the negative pressure in the negative pressure type brake booster gradually decreases, so restarting the engine when this negative pressure falls below a predetermined threshold will restore the negative pressure. In the present invention, the prime mover stopping device changes the negative pressure threshold appropriately according to the road surface condition (slope slope) of the place where the vehicle is stopped. The engine restart frequency is reduced to improve fuel efficiency. In the present embodiment, in addition to such a prime mover stop device, a suitable vehicle is configured by providing the brake force holding device and the driving force control device described above. Details of such a vehicle will be described below.

《Vehicle system configuration etc.》
A system configuration of the vehicle according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a system configuration diagram of a vehicle according to this embodiment, and FIG. 2 is a configuration diagram of a brake force holding device for a vehicle according to this embodiment.
The vehicle according to this embodiment is a hybrid vehicle including an engine 1 that is an internal combustion engine that uses gasoline as a power source as a prime mover and a motor 2 that uses electricity as a power source, and a belt-type continuously variable transmission 3 ( Hereinafter, it is described as CVT3). The vehicle of the present invention may be only the engine 1 as a prime mover. Further, the transmission is not particularly limited, such as an automatic transmission having a torque converter as a transmission and a manual transmission.

[Engine (prime mover), CVT (transmission), motor (prime mover)]
The engine 1 is controlled by a fuel injection electronic control unit (hereinafter referred to as FIECU). The FIECU is integrated 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 controlled by a motor electronic control unit (hereinafter referred to as MOTECU) 5. Further, the CVT 3 is controlled by a CVT electronic control unit (hereinafter referred to as CVTECU) 6.

  Furthermore, the drive shaft 7 to which the drive wheels 8 are mounted is attached to the CVT 3. The drive wheels 8 and 8 are equipped with disc brakes 9 and 9 having wheel cylinders WC (see FIG. 2) and the like. A master cylinder MC is connected to the wheel cylinders WC of the disc brakes 9 and 9 via a brake force holding device RU. Depression from the brake pedal BP is transmitted to the master cylinder MC via the master power MP.

  The engine 1 is an internal combustion engine that uses thermal energy, and drives the drive wheels 8 and 8 via the CVT 3 and the drive shaft 7. The engine 1 is started or stopped by a driver manually turning on and off an ignition switch, and is automatically stopped or started by a motor stop device described later.

  The motor 2 has an assist mode that assists driving by the engine 1 using electrical energy from a battery (not shown). The motor 2 has a regenerative mode in which kinetic energy generated by rotation of the drive shaft 7 is converted into electric energy and stored in a battery (not shown) when no assist is required (downhill, deceleration, etc.). It has a start mode for starting.

  The CVT 3 continuously changes the gear ratio by winding an endless belt between the drive pulley and the driven pulley and changing each pulley width to change the winding radius of the endless belt. Then, the CVT 3 connects the start clutch to the output shaft, engages the start clutch, and transmits the output of the engine 1 and the like shifted by the endless belt to the drive shaft 7 via the output side gear of the start clutch. To do. Note that a vehicle including the CVT 3 is capable of creeping during idling and includes a driving force control unit DCU that reduces the driving force of the creep.

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

  The driving force control unit DCU determines in CVTECU 6 conditions to make a weak creep state, a condition to make a medium creep state, a condition to make a strong creep state, and a condition to make a strong creep state during traveling, which will be described later, and the driving force of the starting clutch The transmission capacity is changed to switch to the preset driving force in each creep state. Further, when the driving force control unit DCU detects whether the vehicle has moved backward or moved forward when starting uphill, the driving force control unit DCU increases the driving force transmission capacity of the starting clutch to switch to the strong creep state. The driving force control unit DCU determines the conditions for switching the creep driving force by the CVTECU 6 and transmits a hydraulic pressure command value to the linear solenoid valve that controls the engagement hydraulic pressure of the starting clutch from the CVTECU 6 to the CVT 3. Then, the driving force control unit DCU switches the engagement force of the starting clutch based on the hydraulic pressure command value at CVT3. As a result, the driving force transmission capacity is also changed, and the driving force of the creep is switched. Note that the fuel efficiency of the vehicle is improved by reducing the driving force by the driving force control unit DCU. Improvement in fuel efficiency is realized by reducing the load on the engine 1 and reducing the load on the hydraulic pump in the starting clutch. Here, the driving force transmission capacity means the maximum driving force (drive torque) that can be transmitted by the starting clutch. That is, when the driving force generated in the engine 1 exceeds the driving force transmission capacity, the starting clutch cannot transmit the driving force exceeding the driving force transmission capacity to the driving wheels 8 and 8. Incidentally, when the failure detection device DU detects a failure of the brake force holding device RU, switching to the weak creep state by the driving force control device DCU is prohibited.

  The driving force control unit DCU transmits the driving force from the prime mover to the drive wheels 8 and transmits the brake pedal when the driving range is selected in the transmission even when the accelerator pedal is depressed at a predetermined vehicle speed or less. When the BP is depressed, that is, when the brake pedal BP is depressed, the driving force transmitted to the drive wheel 8 is set to the “small state”, and when the brake pedal BP is not depressed, the driving force is set to the “large state”. To do. Thus, the reason why the driving force is set to the “small state” when the brake pedal BP is depressed is to suppress vehicle body vibration caused by the braking force being controlled by the braking force. In addition, even if the driver depresses the brake pedal BP strongly and the driving force of the engine 1 disappears, the vehicle does not move backward due to its own weight when stopping on a slope. On the other hand, when the brake pedal BP is released, the driving force is set to a “large state” in order to be able to resist a certain amount of slope even if the braking force is not used, in addition to preparing for starting and acceleration of the vehicle. is there.

  The creep driving force of the vehicle according to the present embodiment has three magnitudes: (i) a large state and (ii) a small state, and (iii) an intermediate state between the large state and the small state. Have The driving force transmission capacity in each state is preset to be large when the driving force is large, small when the driving force is small, and medium when the driving force is intermediate. In this embodiment, a state where the driving force (creep driving force) is large is a strong creep state, a state where the driving force is small is a weak creep state, and a state where the driving force is intermediate between the large state and the small state is a medium creep state. Call it. Furthermore, the strong creep state includes a level where the driving force is large and a small level. The large level is simply referred to as a strong creep state, and the small level is referred to as a strong creep state during running. The strong creep state is a state having a driving force commensurate with a gradient having an inclination of 5 °. The strong creep state during running is a driving force smaller than the strong creep state, and is a state before the switching to the weak creep state. The weak creep state is a state where there is almost no driving force. The medium creep state is a state having a driving force that is about the middle between the strong creep state and the weak creep state, and is an intermediate state when the driving force is gradually reduced in the process of switching from the strong creep state to the weak creep state. . The strong creep state is realized when the accelerator pedal is released at a predetermined vehicle speed or less (that is, in the idling state) and the travel range is selected by the position switch PSW, and the vehicle is released when the brake pedal BP is released. Proceed slowly as if groaning. The weak creep state is realized when the brake pedal BP is further depressed, and the vehicle is stopped or slow.

[Position switch]
The range of the position switch PSW is selected with the shift lever. The range of the position switch PSW is the P range used when parking and stopping, the N range that is neutral, the R range used during back travel, the D range used during normal travel, and when sudden acceleration or strong engine braking is required. There is an L range to do. In the present embodiment, the traveling range refers to three ranges of the D range, the L range, and the R range in which the vehicle can travel. Further, in the present embodiment, when the D range is selected with the position switch PSW, the mode switch MSW can select the D mode which is the normal running mode and the S mode which is the sports running mode. Incidentally, information on the position switch PSW and the mode switch MSW is transmitted to the CVTECU 6 and further to the meter 10. The meter 10 displays range information and mode information selected by the position switch PSW and the mode switch MSW. In the present embodiment, the driving force of the creep is reduced (that is, the driving force is set to the medium creep state or the weak creep state) when the position switch PSW is in the D range or the L range. When in range, strong creep is maintained. In the N range and the P range, the driving force is not transmitted to the driving wheels 8 and 8, but the driving force transmission capacity is reduced and the form is switched to the weak creep state. These points will be described in detail later.

[ECUs]
The FI ECU included in the FI / MG ECU 4 controls the fuel injection amount so as to achieve an optimum air fuel consumption ratio, and controls the engine 1 in an integrated manner. The FI ECU receives information indicating the throttle opening, the state of the engine 1, and the like, and controls the engine 1 based on each information. The MGECU included in the FI / MG ECU 4 mainly controls the MOTECU 5 and determines the engine automatic stop condition and the engine automatic start condition. Information indicating the state of the motor 2 is transmitted to the MGECU, and information indicating the state of the engine 1 is input from the FIECU, and a mode switching instruction for the motor 2 is given to the MOTECU 5 based on each information. Also, information indicating the state of the CVT 3, information indicating the state of the engine 1, range information of the position switch PSW, information indicating the state of the motor 2, and the like are transmitted to the MGECU, and the engine 1 is automatically stopped based on each information. Or, the automatic start is determined.

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

  The CVT ECU 6 controls the transmission ratio of the CVT 3 and the driving force transmission capacity of the starting clutch. The CVT ECU 6 receives information indicating the state of the CVT 3, information indicating the state of the engine 1, range information of the position switch PSW, etc., and controls the hydraulic pressure of each cylinder of the drive pulley and the driven pulley of the CVT 3 and the hydraulic pressure of the starting clutch. A signal or the like for transmitting is transmitted to the CVT 3. Further, the CVTECU 6 includes a control unit CU that controls ON (blocking) / OFF (communication) of the electromagnetic valves SV (A) and SV (B) (see FIG. 2) of the brake force holding device RU, and includes the electromagnetic valve SV ( In order to turn on (shut off) / off (communicate) A) and SV (B), the brake force holding device RU is energized. Further, the CVTECU 6 determines switching of the creep driving force, and also determines that the driving force is increased when the vehicle movement is detected during the operation of the brake force holding device RU, and the determined information is used to drive the CVT 3. To the force control unit DCU. The CVTECU 6 includes a failure detection device DU in order to detect a failure of the brake force holding device RU. The CVTECU 6 determines whether to switch the driving force of the creep and increases the driving force when detecting the movement of the vehicle, and applies to the linear solenoid valve that controls the engagement hydraulic pressure of the starting clutch based on the determination result. Transmit hydraulic pressure command value.

[Brake (braking force holding device)]
The disc brakes 9 and 9 sandwich a disc rotor that rotates integrally with the drive wheels 8 and 8 with a brake pad using a wheel cylinder WC (see FIG. 2) as a drive source, and obtain a braking force by the frictional force thereof. . The brake fluid pressure of the master cylinder MC is supplied to the wheel cylinder WC via the brake force holding device RU.

  The brake force holding device RU holds the brake force by applying the brake fluid pressure to the wheel cylinder WC even after the depression of the brake pedal BP is released. The brake force holding device RU includes a control unit CU in the CVTECU 6 in its configuration. The configuration of the brake force retaining device RU will be described later in detail (see FIG. 2).

  In addition, when the solenoid valve is turned on / off, “in a normally open solenoid valve, when the solenoid valve is turned on, the solenoid valve is closed and becomes a blocking position where the flow of brake fluid is cut off. Then, the solenoid valve is opened and the communication position allowing the flow of the brake fluid is reached. On the other hand, in the case of a normally closed solenoid valve, when the solenoid valve is turned on, the solenoid valve is opened to reach a communication position that allows the flow of brake fluid. When the solenoid valve is turned off, the solenoid valve is closed and the brake fluid is closed. It will be a blocking position to block the flow of "." As will be described later, the solenoid valves SV (A) and SV (B) in the present embodiment are normally open solenoid valves (proportional solenoid valves). In addition, the drive circuit provided in the control unit CU supplies currents to the electromagnetic coils of the solenoid valves SV (A) and SV (B) to turn on / off the solenoid valves SV (A) and SV (B). The amount is calculated, and the solenoid valves SV (A) and SV (B) are energized.

  The master cylinder MC is a device that changes the depression of the brake pedal BP to hydraulic pressure. Further, in order to assist the depression of the brake pedal BP, a master power MP is provided between the master cylinder MC and the brake pedal BP. The master power MP is a device that increases the braking force by adding a negative pressure generated by driving the engine 1 to the force by which the driver depresses the brake pedal BP, thereby reducing the pedaling force during braking. Note that a pressure sensor (not shown) is provided in the constant pressure chamber of the master power MP, and the negative pressure in the master power MP is detected by this pressure sensor. Further, the brake pedal BP is provided with a brake switch BSW, and this brake switch BSW detects whether the brake pedal BP is depressed or released.

[Longitudinal acceleration sensor]
The longitudinal acceleration sensor (tilt determination means) 11 detects acceleration along the longitudinal direction of the vehicle. When the vehicle is stopped on a slope, it follows the slope of the gravitational acceleration applied to the vehicle. The component is detected. In other words, the detection signal of the longitudinal acceleration sensor 11 when the vehicle is stopped on a slope includes information indicating the gravitational acceleration and the slope of the slope.

[Motor stop device]
The prime mover stopping device provided in this vehicle is constituted by FI / MG ECU 4 and CVT ECU 6. The prime mover stop device can automatically stop the engine 1 when the vehicle is stopped. The prime mover stop device determines the engine automatic stop condition by FI / MG ECU 4 and CVT ECU 6. The engine automatic stop condition will be described later in detail. When it is determined that all the engine automatic stop conditions are satisfied, the engine stop command is transmitted from the FI / MG ECU 4 to the engine 1 to automatically stop the engine 1. The vehicle further improves fuel efficiency by automatically stopping the engine 1 by the prime mover stop device. The prime mover stop device determines the engine automatic start condition by the FI / MGECU 4 and the CVTECU 6 when the engine 1 is automatically stopped by the prime mover stop device. When the engine automatic start condition is satisfied, an engine start command is transmitted from the FI / MG ECU 4 to the MOTECU 5, and further a command to start the engine 1 is transmitted from the MOTECU 5 to the motor 2 so that the engine 1 is automatically started by the motor 2. At the same time, make a strong creep condition. The engine automatic start condition will be described later in detail. Further, the prime mover stopping device sets a “threshold value” in a condition that “a booster negative pressure (negative pressure of the master power MP) has become smaller than a predetermined threshold value” among a plurality of engine automatic start conditions according to a road surface condition. It has a function to change. Specifically, when the motor stop device receives a signal detected by the longitudinal acceleration sensor 11 when the vehicle is stopped, the prime mover calculates the slope of the road surface based on this signal, and based on this slope and the map shown in FIG. It has a function to change the negative pressure threshold. Incidentally, when the failure detection device DU detects a failure of the brake force holding device RU, the operation of the prime mover stop device is prohibited.

  The prime mover stop device described above includes “engine stop means (including fuel injection device and the like)”, “engine start means (including MOTECU 5 and motor 2 and the like)”, and “engine stop instruction section”. , “Engine start instruction unit”, “engine control device” and “tilt determination means (including the longitudinal acceleration sensor 11 described above)”.

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

  A signal transmitted from the longitudinal acceleration sensor 11 to the FI / MG ECU 4 will be described. V_GRA is acceleration detected by the longitudinal acceleration sensor 11 (data including the slope of the slope), and this acceleration is used particularly for calculation of the slope in the present embodiment.

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

  A signal transmitted from FI / MG ECU 4 to CVT ECU 6 and MOT ECU 5 will be described. V_NEP is the rotational speed of the engine 1.

  A signal transmitted from CVT ECU 6 to FI / MG ECU 4 will be described. F_MCRPON is a flag indicating whether or not the vehicle is in the middle creep state, and is 1 when the vehicle is in the middle creep state and 0 when the vehicle is not in the middle creep state. When F_MCRPON is 1, the engine 1 is requested to blow medium air in the middle creep state (air weaker than strong creep). F_AIRSCRP is a strong air request flag in the strong creep state, and is 1 when blowing strong air in the strong creep state, and 0 when not blowing. When F_MCRPON and F_AIRSCRP are both 0, the FI / MG ECU 4 blows weak air in the weak creep state. By the way, in order to keep the engine speed at idling constant regardless of whether it is in strong creep, medium creep, or weak creep, air corresponding to each of the strong creep, medium creep, and weak creep conditions is used. It is necessary to adjust the engine output by blowing. When the load of the engine 1 is high as in the strong creep state, it is necessary to blow strong air (strong air in the strong creep state). Note that blowing air refers to sending air from the air passage that bypasses the throttle valve of the engine 1 to the intake pipe downstream of the throttle valve. The strength of the air is adjusted by controlling the opening of the air passage to adjust the amount of air to be sent. F_CVTOK is a flag determined by the CVT ECU 6 in the engine automatic stop condition, and is a flag indicating whether or not all the conditions are satisfied. The flag is 1 when satisfied or 0 when not satisfied. The engine automatic stop condition for F_CVTOK will be described later in detail. F_CVTTO is a flag indicating whether or not 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 0 when it is lower than the predetermined value. The oil temperature of the CVT 3 is estimated from the electric resistance value of a 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 R range is selected in the range of the position switch PSW, and is 1 for the R range and 0 for other than the R range. F_POSDD is a flag indicating whether or not the D range is selected in the range of the position switch PSW and the mode of the mode switch MSW, and is 1 in the case of the D range D mode and in a case other than the D range D mode. 0. The FI / MG ECU 4 determines that any one of the D range S mode and the L range is selected when information indicating the D range D mode, the R range, the P range, and the N range is not input.

  A signal transmitted from the engine 1 to the FI / MG ECU 4 and the CVT ECU 6 will be described. V_ANP is a negative pressure value of the intake pipe of the engine 1. V_TH is the throttle opening. 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 force retaining device RU arranged 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.

  A signal transmitted from CVT 3 to FI / MG ECU 4 and CVT ECU 6 will be described. V_VSP1 is a vehicle speed pulse issued from one of the two vehicle speed pickups provided in CVT3. Based on this vehicle speed pulse, the vehicle speed is calculated.

  A signal transmitted from CVT 3 to CVT ECU 6 will be described. V_NDRP is a pulse indicating the rotational speed of the drive pulley of CVT3. V_NDNP is a pulse indicating the rotational speed of the driven pulley of CVT3. V_VSP2 is a vehicle speed pulse issued from the other of the two vehicle speed pickups provided in CVT3. V_VSP2 is more accurate than V_VSP1, and is used for calculating the slip amount of the starting clutch of 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 an output torque value of the motor 2 and is the same value as V_MOTTRQ. I_MOT is information such as the amount of power generated by the motor 2 indicating an electric load. Note that all the electric power consumed by the vehicle including the motor driving power is generated by the motor 2.

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

  A signal transmitted from the master power MP to the 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.

  A signal transmitted from the position switch PSW to the FI / MG ECU 4 will be described. Only when either the N range or the P range is selected by the position switch PSW, N or P is transmitted as the position information.

  A signal transmitted from CVT ECU 6 to CVT 3 will be described. V_DRHP is a hydraulic pressure command value to the linear solenoid valve that controls the hydraulic pressure of the cylinder of the drive pulley of CVT3. V_DNHP is a hydraulic pressure command value to the linear solenoid valve that controls the hydraulic pressure of the cylinder of the driven pulley of CVT3. Note that the transmission ratio of the CVT 3 is changed by V_DRHP 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. Note that the engagement force (that is, the driving force transmission capacity) of the starting clutch is changed by V_SCHP.

  A signal transmitted from the CVT ECU 6 to the brake force retaining device RU will be described. V_SOLA is the amount of current that flows through the electromagnetic coil in order to turn ON (close) / OFF (open) the electromagnetic valve SV (A) (see FIG. 2) of the brake force holding device RU. V_SOLB is the amount of current that flows through the electromagnetic coil in order to turn ON (close) / OFF (open) the electromagnetic valve SV (B) (see FIG. 2) of the brake force holding device RU. Note that a control current I described later is V_SOLA and V_SOLB itself.

  A signal transmitted from the position switch PSW to the CVT ECU 6 will be described. Which position of the N range, P range, R range, D range or L range is selected by the position switch PSW is transmitted as position information.

  A signal transmitted from the mode switch MSW to the CVT ECU 6 will be described. Whether the D mode (normal running mode) or the S mode (sport running mode) is selected by the mode switch MSW 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.

  A signal transmitted from the brake switch BSW to FI / MG ECU 4 and CVT ECU 6 will be described. F_BKSW is a flag indicating whether the brake pedal BP is depressed (ON) or released (OFF). The flag F_BKSW is 1 when depressed, and 0 when depressed.

  A signal transmitted from the CVTECU 6 to the meter 10 will be described. Which position of the N range, P range, R range, D range or L range is selected by the position switch PSW is transmitted as position information. Further, whether the D mode (normal running mode) or the S mode (sport running mode) is selected by the mode switch MSW is transmitted as mode information.

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

  In addition to the flag shown in FIG. 1, the flag includes F_BKTH used by the control unit CU to determine whether to hold the braking force (see FIGS. 3 and 6A). The control unit CU sets F_BKTH to 1 when the brake operation release speed exceeds the threshold value while the brake switch BSW is ON. Further, the control unit CU sets F_BKTH to 0 when the brake switch BSW is turned off or when the brake pedal BP is stepped on (when the brake operation release speed becomes a negative value). With this F_BKTH, the control unit CU performs holding of the braking force, release of holding of the braking force, and the like. Specific control will be described later.

《Brake force holding device》
The brake force holding device RU detects the brake operation amount of the driver, and based on the release speed of the brake operation amount, the brake force holding device RU applies the brake force to the vehicle until the start driving force is generated in the vehicle itself even after the driver releases the brake operation. Make it work. However, the brake force holding device RU operates on the condition that the brake operation release speed exceeds the threshold value and holds the brake force.

  As shown in FIG. 2, the brake force retaining device RU according to the present embodiment is incorporated in the brake hydraulic pressure passage FP of the hydraulic brake device BK, and has a brake hydraulic pressure passage FP between the master cylinder MC and the wheel cylinder WC. There is an electromagnetic valve SV that switches to a communication position that communicates with the brake fluid pressure passage FP and switches to a cutoff position that maintains the brake fluid pressure of the wheel cylinder WC (that is, maintains the brake force). In the solenoid valve SV, the amount of current flowing through an electromagnetic coil (not shown) is controlled by the control unit CU, and is switched between a communication position and a shut-off position according to the amount of current, and reduced while adjusting the held brake fluid pressure. (Gradual reduction).

  First, the hydraulic brake device BK will be described, and then the brake force holding device RU will be described (both see FIG. 2). The brake hydraulic circuit BC of the hydraulic brake device BK includes a master cylinder MC, a wheel cylinder WC, and a brake hydraulic pressure passage FP that connects 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) and BC (B)), and one system has failed. Even when the rest of the system, the minimum braking force can be obtained.

  The master cylinder MC has a piston MCP inserted in the main body, and when the driver depresses the brake pedal BP, the piston MCP is pushed, pressure is applied to the brake fluid in the master cylinder MC, and mechanical force is applied to the brake fluid pressure. Converted to (pressure applied to the brake fluid). When the driver releases his / her foot from the brake pedal BP and releases the depression, the piston MCP is returned to the original state by the force of the return spring MCS, and at the same time, the brake fluid pressure is also restored. The master cylinder MC shown in FIG. 2 is a tandem master cylinder MC in which two main bodies of the master cylinder MC are divided into two by arranging two pistons MCP from the viewpoint of fail-and-safe that two independent brake hydraulic circuits BC are provided. is there.

  In order to reduce the operating force of the brake pedal BP, a master power MP (brake booster) is provided between the brake pedal BP and the master cylinder MC. The master power MP shown in FIG. 2 is of a vacuum (negative pressure) servo type, and the negative pressure is taken out from the intake manifold of the engine 1 so that the driver can easily operate the brake pedal BP.

  The brake fluid pressure passage FP serves as a flow path that connects the master cylinder MC and the wheel cylinder WC, and transmits the brake fluid pressure generated in the master cylinder MC to the wheel cylinder WC by moving the brake fluid. When the brake fluid pressure of the wheel cylinder WC is higher, it plays a role of a flow path for returning the brake fluid from the wheel cylinder WC to the master cylinder MC. Since the brake fluid pressure circuit BC is provided independently as described above, the brake fluid pressure passage FP is also provided with two independent systems. A brake fluid pressure circuit BC including a brake fluid pressure passage FP shown in FIG. 2 has one brake fluid pressure circuit BC (A) braking the right front wheel and the left rear wheel, and the other brake fluid pressure circuit BC ( B) is an X piping system for braking the left front wheel and the right rear wheel. Note that the brake hydraulic circuit BC is not an X piping system, but may be a front and rear division system 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 drive wheel 8 and is a mechanical force for braking the drive wheel 8 with the brake fluid pressure generated by the master cylinder MC and transmitted to the wheel cylinder WC through the brake fluid pressure passage FP. Brake force). In the wheel cylinder WC, a piston is inserted in the main body, and this piston is pushed by the brake hydraulic pressure, and in the case of a disc brake, the brake pad or the brake shoe is operated in the case of a drum brake to brake the drive wheel 8. To produce braking force. In addition to the above, a brake hydraulic pressure control valve for controlling the brake hydraulic pressure of the front wheel cylinder WC and the brake hydraulic pressure of the rear wheel cylinder WC is provided as necessary.

Next, the brake force retaining device RU will be described (see FIG. 2).
The brake force holding device RU includes an electromagnetic valve SV and a check valve CV, a brake operation amount detector BG, and a control unit CU (included in the CVTECU 6). Of these, the electromagnetic valve SV is a master cylinder. The brake fluid pressure passage FP connecting the MC and the wheel cylinder WC is incorporated. Incidentally, the brake force retaining device RU includes a brake hydraulic pressure sensor PG in the brake hydraulic pressure passage FP in order to detect the brake hydraulic pressure of the master cylinder MC. In the present embodiment, the brake hydraulic pressure sensor PG Also serves as a brake operation amount detector BG.

  The solenoid valve SV is actuated by an electrical signal from the control unit CU and is in a shut-off state in which the brake fluid flow in the brake fluid pressure passage FP is shut off at the shut-off position (ON), and in a brake fluid pressure passage FP at the communication position (OFF). The brake fluid flow is allowed to flow. Further, the solenoid valve SV has a pressure adjustment state in which the brake fluid pressure is adjusted while repeatedly switching off / allowing the flow of the brake fluid in the brake fluid pressure passage FP by switching between the shut-off position (ON) and the communication position (OFF). . Incidentally, the two solenoid valves SV (A) and SV (B) shown in FIG. 2 are both in the communication position. Even when the driver releases the depression of the brake pedal BP at the time of starting uphill, the electromagnetic valve SV can maintain the brake hydraulic pressure in the wheel cylinder WC and prevent the vehicle from moving backward. Note that the reverse means that the vehicle travels in a direction opposite to the direction in which the driver tries to advance due to the weight of the vehicle (downhill).

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

  When the solenoid valve SV is switched to the communication state, the flow of the brake fluid between the wheel cylinder WC and the master cylinder MC is allowed at a stretch, and the brake force held in the shut-off state is instantaneously released. Note that when the solenoid valve SV is maintained in a communicating state, a brake fluid pressure proportional to the depression force of the brake pedal BP is transmitted to the wheel cylinder WC.

  When the solenoid valve SV is switched to the pressure regulation state, the solenoid valve SV is switched alternately between the shut-off position and the communication position, and the flow rate of the brake fluid flowing from the wheel cylinder WC to the master cylinder MC is adjusted. Then, the brake fluid pressure (and hence the brake force) is reduced while adjusting, and the holding brake force is gradually reduced. As will be described later, the gradual decrease of the braking force is realized by gradually decreasing the value of the control current I (V_SOLA, V_SOLB) supplied from the control unit CU to the solenoid valve SV (decreases at the first decrease rate). ).

  In the present embodiment, when the solenoid valve SV is switched from the communication state to the cutoff state, the solenoid valve SV is switched without going through the pressure regulation state. On the other hand, when the solenoid valve SV is switched from the shut-off state to the communication state, the solenoid valve SV is switched via the pressure regulation state. The conditions for switching the solenoid valve SV to the cutoff state, the communication state, or the pressure regulation state will be described in detail later.

  Here, examples of the solenoid valve SV that can reduce the brake fluid pressure while adjusting the brake fluid pressure include a proportional solenoid valve. As an example, the proportional solenoid valve (solenoid valve SV in FIG. 2) is a sum of an urging force by a spring S built in the valve and a product obtained by multiplying an applied pilot pressure by a pressure receiving area (hereinafter referred to as “biasing force or the like”). ) Repeats opening and closing (communication / interruption) of the valve so as to balance the electromagnetic force generated by an electromagnetic coil (not shown) built in the valve. If the proportional solenoid valve is a normally open type, if the biasing force or the like is larger than the electromagnetic force, the valve is opened and becomes a communication position. The communication position is maintained until electromagnetic force> biasing force or the like. On the other hand, if the urging force or the like is smaller than the electromagnetic force, the valve is closed and the blocking position is reached. Further, the blocking position is maintained until electromagnetic force <biasing force or the like. Here, the pilot pressure is a brake fluid pressure of the wheel cylinder WC.

  The electromagnetic force of the proportional solenoid valve varies depending on the current value of the control current supplied to the electromagnetic coil. In the case of a normally open proportional solenoid valve, if the current value is gradually decreased from the large current value in the shut-off state, the electromagnetic force gradually weakens, so the communication position and the shut-off are balanced by the balance between the urging force and the electromagnetic force. The brake fluid pressure can be adjusted while switching the position. When the brake fluid pressure held in the wheel cylinder WC is reduced, the brake fluid pressure (that is, the brake force) can be gradually reduced by gradually reducing the current value of the control current. In the case of a normally open proportional solenoid valve, the communication state is maintained when the current value of the control current supplied to the electromagnetic coil is zero (substantially zero).

  By the way, in the present embodiment, it is assumed that the solenoid valve SV is a proportional solenoid valve. However, the present invention is not necessarily limited to the proportional solenoid valve, and can create the above-described cutoff state, communication state, and pressure regulation state. Any type of valve is acceptable. In addition, the solenoid valve SV includes a normally closed type that becomes a communication position when energized and a normally open type that becomes a cut-off position when energized, but any solenoid valve can be used. However, a normally open solenoid valve is preferable from the viewpoint of fail-and-safe. This is because when the energization is cut off due to a failure or the like, the normally closed solenoid valve does not work or the brake keeps working. This embodiment will be described on the assumption that the solenoid valve SV is a normally open type.

  The check valve CV is provided as necessary, but when the solenoid valve SV is in the cutoff position and the driver depresses the brake pedal BP, the brake fluid pressure generated in the master cylinder MC is applied to the wheel cylinder WC. Play a role to communicate. The check valve CV operates effectively when the brake fluid pressure generated in the master cylinder MC exceeds the brake fluid pressure of the wheel cylinder WC, and quickly responds to the increase in the brake pedal BP of the driver. Increase brake fluid pressure. Note that if the brake valve BP of the master cylinder MC exceeds the brake hydraulic pressure of the wheel cylinder WC, the solenoid valve SV that is once closed is brought into a communication state. It is not necessary to provide the check valve CV because it can cope with an increase in the number of steps. That is, when the brake fluid pressure value on the master cylinder MC side and the brake fluid pressure value on the wheel cylinder WC side are detected, and the former brake fluid pressure value exceeds the latter brake fluid pressure, the solenoid valve SV is in a communication state. With the configuration, the check valve CV can be dispensed with.

  The brake switch BSW detects whether or not the brake pedal BP is depressed. Then, this detected value is transmitted to the control unit CU.

  The brake fluid pressure sensor PG is provided in the brake fluid pressure passage FP and detects the brake fluid pressure on the master cylinder MC side. As described above, the brake fluid pressure sensor PG also serves as the brake operation amount detector BG, detects the driver's brake operation amount, and transmits the detected value V_BG to the control unit CU. Incidentally, the brake fluid pressure on the master cylinder MC side detected by the brake fluid pressure sensor PG is proportional to the brake operation amount of the driver, unlike the brake fluid pressure on the wheel cylinder WC side. Therefore, the brake hydraulic pressure sensor PG can also serve as the brake operation amount detector BG, and can sufficiently detect the driver's brake operation amount. The brake operation amount detector BG correctly measures the brake operation release speed in any situation where the driver depresses the brake pedal BP strongly, depresses it moderately, or depresses it gently. can do. The brake operation amount detector BG includes a rotational displacement meter that detects the rotation angle of the support shaft of the brake pedal BP, a sensor that detects the depression force of the brake pedal BP, a sensor that detects the stroke of the brake pedal, a master cylinder MC or a master A device capable of calculating the amount of brake operation per unit time (that is, the brake operation release speed), such as one that detects the stroke of the piston of the power MP, may be used.

  The control unit CU determines whether the electromagnetic valve SV is in the communication state, the cutoff state, or the pressure adjustment state from the detection value V_BG of the brake operation amount detector BG, the flag F_BKTH, the signal of the brake switch BSW, the vehicle speed, and the like. When the brake operation release speed exceeds the threshold value (F_BKTH = 1), the control current I (V_SOLA, V_SOLB) is supplied to the solenoid valve SV to operate the brake force holding device RU.

  When the threshold is set to a large value, there is an advantage that a brake operation that is not intended to release the depression of the brake pedal BP by the driver can be cut as noise. On the other hand, if the threshold value is set large, the brake pedal BP is released by the time the brake operation release speed reaches the threshold value, so that the braking force to be held is small and the vehicle may reverse on an uphill. There is an inconvenience. Therefore, the threshold is set by comparing and considering the profit and the disadvantage when this is increased. Incidentally, in the case of the present embodiment, since the braking force is increased only by the driver's braking operation, the above-described inconvenience is likely to occur if the threshold value is set large.

  In the present embodiment, the control unit CU operates (i) the brake force holding device RU when the brake operation release speed exceeds a threshold value. The control unit CU supplies (ii) the current value of the control current I for putting the solenoid valve SV in the shut-off state to the solenoid valve SV with a constant magnitude regardless of the brake operation release speed. In addition, the control unit CU (iii) immediately decreases the current value of the control current I supplied to the solenoid valve SV at a predetermined rate (a first reduction speed described later) to bring the solenoid valve SV into a pressure regulation state. And Accordingly, depending on the relationship between the current value of the control current I supplied to the solenoid valve SV and the brake fluid pressure held in the wheel cylinder WC, (i) the control current I is supplied and the solenoid valve SV is turned off at the same time. When shifting to the pressure regulation state, (ii) even when the control current I is supplied, the solenoid valve SV is not immediately shut off (when the brake fluid pressure of the wheel cylinder WC is high), (iii) the control current I is supplied Then, there are three cases where the electromagnetic valve SV is in a shut-off state for a while (when the brake fluid pressure of the wheel cylinder WC is small).

[Basic control of brake force holding device]
Next, basic control of the vehicle brake force retaining device RU (control unit CU) according to the present embodiment will be described.
1) The brake force retaining device RU continues to apply a braking force to the vehicle until a starting driving force is generated in the vehicle itself even after the brake operation is released.
(I) The condition “after the brake operation is released” is because the brake force is reduced by releasing the brake operation of the driver, and therefore, if the brake force is not continuously applied to the vehicle, the vehicle goes uphill.
(Ii) The condition “until the start driving force is generated” is that if no start driving force is generated, the solenoid valve SV is shut off (including the regulated pressure state) and no braking force is applied. This is because it causes a setback. Note that “until the start driving force is generated” will be described later as a creep rise.

2) The brake force holding device RU detects the driver's brake operation amount, and is operated based on the brake operation release speed calculated based on the brake operation amount. Specifically, it is operated on condition that the brake operation release speed exceeds a threshold value. The condition that the “threshold value” is set is that, as described above, in addition to the reason that the brake operation that is not intended to release the driver's brake pedal BP is cut as noise, the brake operation release speed is low, such as downhill. In this case, the operation of the brake force retaining device RU is prohibited, and the slow speed advance by smoothly depressing the brake pedal BP is smoothly performed. In other words, if the braking force is maintained at a slow speed on a downhill, it is difficult to control the vehicle in accordance with the driver's will.

3) The brake force retaining device RU immediately regulates the solenoid valve SV in the shut-off state. The reason for setting the pressure regulation state is to achieve a smooth start of the vehicle by gradually reducing (gradually reducing) the braking force to achieve a balance between the increasing driving force and the braking force. . Another reason is that the driver who wants to move forward at a slow speed on the downhill can be operated by loosening the depression of the brake pedal BP.

  By performing such control, it is possible to realize a start without retreat on an uphill and a slow speed advance due to its own weight on a downhill. Even when the brake force holding device RU is operated on a flat ground or a gentle downhill to hold (act) the brake force, the brake force gradually decreases and gradually decreases. Further, when the starting driving force is generated in the vehicle, the holding of the braking force is released. Therefore, the driver's operation is not hindered.

《Specific vehicle control》
Next, what kind of control is performed in the vehicle of the present embodiment will be specifically described (see FIGS. 3 to 9). Here, FIG. 3 shows a control logic for holding the braking force of the braking force holding device. 4A and 4B are diagrams showing the control logic of the driving force control device, where FIG. 4A is a control logic for setting a weak creep state, FIG. 4B is a control logic for setting a strong creep state during driving, and FIG. 4C is a medium creep state. Is the control logic. FIG. 5 shows control logic for automatically stopping the engine of the prime mover stopping device. FIG. 6 is a diagram showing the control logic of the brake force holding device. FIG. 6A is a control logic for releasing the holding of the brake force when the starting drive force is generated in the vehicle itself (first reduction speed → second (B) is a control logic for releasing the holding of the braking force from the viewpoint of fail-and-safe (first reduction speed → a communication state), and (c) is a control for determining the start of creep. Logic. 7A and 7B are diagrams showing control logic of the driving force control device, where FIG. 7A is a control logic for making a strong creep state (vehicle reverse detection version), and FIG. 7B is a control logic for making a strong creep state (vehicle movement detection). Version). FIG. 8 is a diagram showing the control logic of the prime mover stopping device, where (a) is the control logic for automatically starting the engine (vehicle reverse detection version), and (b) is the control logic for automatically starting the engine (vehicle movement detection version). ). FIG. 9 is an example of a vehicle reverse detection method, (a) is a configuration diagram of vehicle reverse detection, (b) is a pulse phase of (i) direction rotation of (a), and (c) is (a). (Ii) The pulse phase of direction rotation.

[When brake force is maintained]
A case where the brake force is held by the brake force holding device RU (when the brake force is applied) will be described. The brake force is maintained when all of the following four conditions are satisfied (see FIG. 3).
I) Brake switch BSW is ON
II) The position switch PSW is not neutral (N range), parking (P range), or reverse (R range).
III) Vehicle speed is 0 km / h
VI) The brake operation release speed exceeds the threshold value (predetermined value) When all of these conditions are satisfied, the control current I is supplied from the control unit CU to the electromagnetic valve SV at a predetermined current value, and the electromagnetic valve SV is shut off. The brake force is maintained. Note that the control unit CU gradually decreases the current value of the control current I of the solenoid valve SV that is in the shut-off state at a first reduction rate that is set in advance, thereby bringing the solenoid valve SV into a pressure-regulating state ( The second reduction rate will be described later). Here, the condition for setting the solenoid valve SV to the cutoff state is determined by the control unit CU of the CVTECU 6. Further, the current value of the control current I for setting the solenoid valve SV of the control current I to the cutoff state, the first decreasing speed for gradually decreasing the current value, and the like are according to a table provided in the control unit CU.

The conditions for maintaining the brake force will be described individually.
I) The condition that “the brake switch BSW is ON” is because when the brake switch BSW is OFF, the wheel cylinder WC has no or very little braking force to be held.

II) The condition that the position switch PSW is not neutral (N range), parking (P range), or reverse (R range) is (i) the brake force holding device RU in the N range and P range. (Ii) In the R range, the strong creep state is maintained, and therefore, the backward movement of the vehicle is suppressed by the driving force in the strong creep state. Therefore, the braking force is maintained in the D range (drive range) and L range (low range).

IV) 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 shut off during traveling. On the other hand, if the vehicle speed is 0 km / h, the vehicle is in a stopped state, so there is no problem in driving operation even if the braking force is maintained. The “vehicle speed is 0 km / h” includes a state where the vehicle is moving slightly.

V) The condition (F_BKTH = 1) that “the brake operation release speed has exceeded the threshold value” causes the driver to loosen the depression of the brake pedal and thus start the vehicle when the brake operation release speed exceeds the threshold value. This is because the intention is clearly recognized. In addition, when the brake operation release speed is slow enough not to exceed the threshold value, the vehicle is positioned on a downhill or the like. In such a case, the brake force is set so that the brake operation can be performed according to the driver's intention. This is because it is appropriate not to operate the holding device RU. Furthermore, it is because it is useless operation to operate the brake force holding device RU and hold the brake force from when the vehicle is stopped until the driver releases the brake pedal BP. For this reason, the fact that the brake operation release speed exceeds the threshold is added to the condition for maintaining the braking force. That is, the braking force is held for the first time when the driver releases the depression of the brake pedal BP at a brake operation release speed equal to or higher than the threshold value.

  Incidentally, when the brake force holding device RU supplies the control current I to the solenoid valve SV, the brake force holding device RU immediately decreases the value of the control current I and tries to adjust the pressure. However, as described above, when the brake fluid pressure of the wheel cylinder WC is large, the pressure regulation state may be established after the communication state is maintained for a while. On the other hand, when the brake fluid pressure of the wheel cylinder WC is small, the pressure regulation state may be entered after the shut-off state is maintained for a while. The case where the holding (action) of the braking force is released will be described later.

[Conditions for issuing a weak creep command]
The vehicle according to the present embodiment is driven under a predetermined condition for reasons such as to reduce the fuel consumption when the vehicle is stopped and to suppress the occurrence of vehicle body vibration by controlling the driving force in the strong creep state with the braking force. Make the force weak creep. Hereinafter, conditions for issuing a weak creep command will be described. The condition for issuing the weak creep command (F_WCRP) is when the following condition I) or II) is satisfied (see FIG. 4A).
I) Position switch PSW is in N range or P range
II) The following (i) and (ii) are satisfied. (I) 1) The brake force holding device RU is normal, 2) The brake switch BSW is ON, and 3) The position switch PSW is forward (DL). Range and 4) Vehicle speed is 5 km / h or less (ii) 5) Vehicle speed after transition to strong creep state> 5 km / h and vehicle speed> 4 km / h, or 6) Weak creep state, or 7) Vehicle speed is 0 km / h and medium Elapsed time after transition to creep state and medium creep state

  If either of the above conditions I) or II) is satisfied, a weak creep command is issued and a weak creep state is entered. Each of the above conditions is determined by the driving force control unit DCU.

The conditions for issuing the weak creep command will be described individually.
I) The condition that the position switch PSW is in the N range or the P range is that the accelerator pedal is quickly depressed simultaneously with switching from the non-traveling range (N / P range) to the traveling range (D / L / R range). Even in such a case, the driving force transmission capacity of the starting clutch is increased rapidly so that smooth starting can be performed. That is, in the weak creep state, the hydraulic chamber of the starting clutch is already filled with pressure oil, and there is no invalid stroke (play) of the pressing piston. Therefore, if the value of pressure oil is increased, the driving force transmission capacity increases rapidly. It should be noted that even if the weak creep state is set in the N / P range, the driving force transmission capacity of the starting clutch is set in advance to the weak creep state capacity, and the driving force from the engine 1 is transmitted to the drive wheels 8. I don't mean. This is different from the weak creep state in the D / L range. Incidentally, in the N / P range, the connection between the engine 1 and the drive wheels 8 is completely cut off by the forward / reverse switching mechanism arranged in series with the starting clutch on the driving force transmission path. That is, neither the forward drive force transmission path nor the reverse drive force transmission path is set in the N / P range. Therefore, no driving force is transmitted from the engine 1 to the driving wheels 8.

  The condition of II) is the basic condition for the conditions from 1) to 4) of (i) to be in the weak creep state, and the condition before entering the weak creep state is from 5) of (ii) Any condition of 7) is a condition for making a weak creep condition.

  1) The condition that the brake force holding device RU is normal is that if the brake force holding device RU is abnormal, the brake force cannot be held after the driver releases the brake, and if the brake force is not held, the slope is weak This is because it is not possible to suppress the reverse of the vehicle. For example, when there is an abnormality such that the solenoid valve SV is not in the shut-off position, if a weak creep command is issued and a weak creep state occurs, the brake fluid pressure on the wheel cylinder WC side is not maintained after the brake operation is released, so that the braking force In addition to weakening, the weak creep condition also weakens the power to climb the vehicle. Therefore, when the driver releases the depression of the brake pedal BP at the start of the hill, the braking force is suddenly lost and the vehicle moves backward on the hill. In this case, by maintaining a strong creep state, retreat on a hill is prevented and hill start (climb start) is facilitated.

  2) The condition that “the brake switch BSW is ON” is because when the brake pedal BP is not depressed, the driver does not want at least a decrease in driving force.

  3) The condition that the position switch PSW is in the forward (D / L) range is for the purpose of improving fuel efficiency in the forward range. In the D range, the weak creep state is set in both the D mode and the S mode. By the way, in the R range, it is not switched to the weak creep state in order to facilitate the garage entry by the strong creep running.

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

  5) The condition “vehicle speed after transition to strong creep state> 5 km / h and vehicle speed> 4 km / h” is that the vehicle is in a weak creep state only by deceleration by depressing the continuous brake. Since the driving force difference between the strong creep state and the weak creep state is large, when the brake pedal BP is depressed, when the strong creep state is switched to the weak creep state, the strong unintended by the driver before the vehicle stops. Creates a feeling of deceleration. In addition, when the vehicle is stopped and the vehicle is going uphill, an instantaneous reverse may occur. Therefore, it is necessary to prevent switching from the strong creep state to the weak creep state. Therefore, when the vehicle enters the strong creep state, the vehicle speed exceeds 5 km / h, the throttle is turned off (depressing the accelerator pedal is released), and the vehicle is not switched to the weak creep state until the vehicle is switched to the strong creep state during driving. In addition, even after the vehicle has entered a strong creep state, even if the vehicle speed exceeds 5 km / h and the driving force decreases (strong creep state during running), for example, when the vehicle is approaching an uphill, the brake pedal BP is not depressed. However, the vehicle speed may decrease to 5 km / h again. At this time, since the brake switch BSW is OFF, the vehicle is in a strong creep state when the vehicle speed drops to 5 km / h. Even in such a case, in order to prevent subsequent switching from the strong creep state to the weak creep state, a condition of vehicle speed> 4 km / h is provided, and when the vehicle speed drops again to 5 km / h, the brake pedal BP If is not stepped on, the switch to the weak creep state is not performed thereafter. If the brake pedal BP is depressed when the vehicle speed is reduced to 5 km / h (the brake switch BSW is ON), switching from the strong creep state during traveling to the weak creep state is executed. That is, when the vehicle speed is reduced to 5 km / h again (the vehicle speed = 5 km / h), the strong creep state is maintained as long as the vehicle speed is 5 km / h or less.

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

  7) The condition that “the vehicle speed is 0 km / h, the middle creep state and the predetermined time elapses after the transition to the middle creep state” is to prevent deterioration of fuel consumption and vehicle body vibration when the vehicle is stopped in the strong creep state. When the vehicle speed drops again to 5 km / h (vehicle speed = 5 km / h), miss the opportunity to switch to the weak creep state (depending on the condition of 5), or once the brake pedal BP is depressed If the vehicle speed is maintained at 5 km / h or less after the release and the vehicle enters the strong creep state, the strong creep state is maintained. Furthermore, if the vehicle continues to stop in a strong creep state while the brake pedal BP is depressed, the fuel consumption deteriorates and the vehicle body vibration continues. Therefore, the vehicle is completely stopped (vehicle speed = 0 km / h), enters a middle creep state that is a driving force intermediate between a strong creep state and a weak creep state, and further enters a middle creep state for a predetermined time ( In this embodiment, if 300 msec), the weak creep state is switched. In this way, the braking force is increased by stepping on the brake pedal BP while the driving force is gradually lowered from the strong creep state to the middle creep state, and further to the weak creep state, so the instantaneous reverse amount on the uphill is also possible. It can be kept as small as possible.

[Conditions for issuing strong creep commands during driving]
The conditions for issuing a strong creep command during travel will be described. The strong creep command during travel (F_MSCRP) is issued when both of the following conditions I) and II) are satisfied (see FIG. 4B). In addition, after a strong creep command during travel, the vehicle enters a strong creep state during travel.
I) Vehicle speed> 5 km / h
II) The throttle is OFF (depressing the accelerator pedal is released). These conditions are determined by the driving force control unit DCU. The reason why the driving force is set to the strong creep state during traveling is that the strong deceleration feeling that is given to the driver before the vehicle stops when the vehicle is switched from the strong creep state to the weak creep state is not generated. Therefore, the driving force is set to be smaller than the driving force in the strong creep state before entering the weak creep state.

The conditions for issuing the above-mentioned strong creep command during traveling will be described individually.
I) The condition “vehicle speed> 5 km / h” is that the vehicle speed is 5 km / h after the vehicle speed once exceeds 5 km / h after the transition to the strong creep state. It is because it is in a weak creep state when it becomes. Further, this is for distinguishing between a strong creep condition when the vehicle speed is 5 km / h or less and a strong creep condition when the vehicle speed exceeds 5 km / h.

  II) The condition that “the throttle is OFF (TH OFF)” is because the driver does not want to increase the driving force and there is no problem even if the driving force is reduced.

[Conditions for issuing a medium creep command]
The conditions under which the medium creep command is issued will be described. The condition for issuing the medium creep command (F_MCRP) is when all of the following conditions I), II) and III) are satisfied (see FIG. 4C).
I) Brake switch BSW is ON
II) The position switch PSW is in the forward (DL) range
III) The vehicle is completely stopped (vehicle speed = 0 km / h). These conditions are determined by the driving force control unit DCU. Also, the driving force is changed to the medium creep state when the vehicle speed drops to 5 km / h again (vehicle speed = 5 km / h) or missed the opportunity to switch to the weak creep state or once entered the weak creep state. If the vehicle speed is maintained at 5 km / h or less after the depression of the brake pedal BP is later released and the vehicle enters a strong creep state, the strong creep state is maintained. Further, if the vehicle continues to stop in a strong creep state, fuel consumption deteriorates and vehicle body vibration continues. Therefore, when the vehicle is stopped, switching from the strong creep state to the weak creep state causes an instantaneous retreat as described above. Therefore, the medium creep state is switched to a middle driving force between the strong creep state and the weak creep state.

The conditions for issuing the above-described medium creep command will be described individually.
I) The condition that “the brake switch BSW is ON” is because, when the brake pedal BP is not depressed, the driver does not want to decrease the driving force at least.

  II) The condition that the position switch PSW is in the forward (D / L) range is a weak creep state in the D range or the L range. Depending on the reason. In the N / P range, the weak creep state is set at the same time as the transmission is switched, so there is no need for the intermediate creep state. Further, in the R range, the strong creep state is maintained, so there is no need for the intermediate creep state.

  III) The condition that “the vehicle is completely stopped (that is, the vehicle speed = 0 km / h)” is a weak creep state in order to suppress deterioration in fuel consumption and vehicle body vibration in a strong creep state when the vehicle is stopped. This is because a medium creep state is required.

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

[Automatic engine stop conditions]
In order to further improve fuel consumption, the engine 1 is automatically stopped when the vehicle is stopped. This condition will be described. When all the conditions shown in FIG. 5 are satisfied, an engine stop command (F_ENGOFF) is issued and the engine 1 is automatically stopped. The engine 1 is automatically stopped by a prime mover stopping device. Therefore, the following engine automatic stop conditions are determined by the prime mover stop device. Note that the automatic stop condition of the engine 1 is determined by the FI / MG ECU 4 and the CVT ECU 6, and determined by the FI / MG ECU 4 and when all the conditions I) to VIII) are satisfied, F_MGSTB is set to 1, and the CVT TECCU 6 determines from IX). When all the conditions of (XV) are satisfied, F_CVTOK becomes 1.

The automatic engine stop conditions will be described individually.
I) The condition that “the brake switch BSW is ON” is for the purpose of alerting the driver. When the brake switch BSW is ON, the driver is in a state of placing his / her foot on the brake pedal BP. Therefore, even if the driving force is lost due to the automatic stop of the engine 1 and the vehicle starts to retreat on the slope, the driver can easily increase the brake pedal BP.

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

III) The condition that “the vehicle speed has once become 5 km / h or more after the engine 1 is started” is for the purpose of facilitating garage entry and garage entry during creep running. This is because it is troublesome if the engine 1 is automatically stopped every time the vehicle is stopped, for example, when the vehicle is turned in or out of the garage.

IV) The condition that “the position switch PSW and the mode switch MSW are in a range other than the R • D (S mode) • L range (that is, the N • D (D mode) • P range)” is due to the following reason. . This is because when the position switch PSW is in the R range, it is troublesome if the engine 1 is automatically stopped frequently when entering the garage. This is because when the position switch PSW is in the D range and the mode switch MSW is in the S mode, or when the position switch PSW is in the L range, the driver expects that the vehicle can start quickly.

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

VI) The condition that “the electric load is below a predetermined value” is to ensure the supply of electricity to the load.

VII) The condition that “the negative pressure of the constant pressure chamber of the master power MP is equal to or greater than a predetermined value” is that if the negative pressure of the constant pressure chamber of the master power MP is small, the stepping force is amplified when the brake pedal BP is depressed. The reason for this is that the braking effect is reduced (it is not assisted). That is, when the engine 1 is stopped in a state where the negative pressure in the constant pressure chamber is small, the negative pressure in the constant pressure chamber is further reduced because the negative pressure in the constant pressure chamber is introduced from the intake pipe of the engine 1. Therefore, the amplification of the depression force when the brake pedal BP is depressed is reduced, and the braking effectiveness is reduced.

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

IX) The condition that “all the automatic stop conditions for the engine 1 in the FI / MGECU 4 are satisfied and ready” is that all the automatic stop conditions for the engine 1 to be determined by the FI / MG ECU 4 are not satisfied. This is because it is not appropriate to automatically stop the engine 1.

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

XI) The condition that “the ratio of CVT3 is low” is because smooth start may not be possible when the ratio (pulley ratio) of CVT3 is not low.

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

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

XIV) The condition that the brake force holding device RU is normal is that the brake force is maintained when the driver releases the brake pedal BP when there is an abnormality in the brake force holding device RU. The reason for this is to keep the vehicle in a strong creep condition and prevent the vehicle from retreating on a slope.

XV) The condition “[1] Brake switch BSW is ON” or [2] Position switch PSW is N · P range ”is for the following reason.
1) When the brake switch BSW is ON, the braking force is maintained. Therefore, even if the engine 1 automatically stops and the driving force is lost, the vehicle does not reverse on the uphill. The driver is in a state where his / her foot is placed on the brake pedal BP. Therefore, even if the driving force is lost due to the automatic stop of the engine 1 and the vehicle starts to retreat on the slope, the driver can easily increase the brake pedal BP.
2) When the position switch PSW is in the P range or the N range and the vehicle is stopped, the driver intends to stop the vehicle completely, so there is no problem even if the engine 1 is stopped.

[When braking force is released]
Next, a case where the braking force holding device RU releases the holding (action) of the braking force will be described. Note that the holding release of the braking force is released when the starting driving force is generated in the vehicle itself (in the case of the condition of FIG. 6 (a)) and when it is released from the viewpoint of fail-and-safe (see FIG. 6). 6 (b)).

The holding of the braking force is canceled when the starting driving force is generated in the vehicle itself when the following condition is satisfied (see FIG. 6A).
I) Creep start-up and brake operation release speed is greater than or equal to threshold value When this condition is satisfied, the control unit CU supplies control to the solenoid valve SV that is in a pressure-regulating state at the first reduction speed. The current value of the current I is decreased until the communication state is established at the second decreasing speed, and the holding of the brake fluid pressure is released.

  I) The condition that “creep rise (F_SCDLY = 1) and brake operation release speed is equal to or higher than a threshold (F_BKTH = 1)” is a process in which the driving force increases to a strong creep state. However, considering the inertial force and rolling resistance of the vehicle (plus the driving force in the increasing process), it is possible to suppress the retreat on the uphill and start the vehicle without a sudden feeling on the downhill. This is because it can be realized. The first and second reduction speeds for reducing the current value of the control current I are set such that the second reduction speed has a larger reduction ratio, so that the braking force is reduced quickly and unnecessary brake drag is caused. It does not occur. Similarly to the first decrease rate, the second decrease rate follows the table provided in the control unit CU.

On the other hand, the holding of the braking force is canceled from the viewpoint of fail-and-safe or the like when any of the following conditions is satisfied (see FIG. 6B).
I) The position switch PSW is in the N / P range and the brake switch BSW is OFF.
II) When one of these conditions is satisfied that the vehicle speed has exceeded 20 km / h, the control unit CU controls the control current I to be supplied to the solenoid valve SV in the pressure-decreasing state of the first decreasing speed. The current value is set to zero (substantially zero) at once, and the solenoid valve SV in the pressure regulation state is switched to the direct communication state to release the holding of the braking force at once.

The conditions for releasing the holding of the braking force by switching the solenoid valve SV in the pressure regulation state of the first decreasing speed to the direct communication state will be described individually.
I) The condition “the position switch PSW is in the N · P range and the brake switch BSW is OFF” is because the useless operation of the brake force retaining device RU is omitted.

II) The condition that “the vehicle speed has exceeded 20 km / h” is to eliminate unnecessary brake drag as a fail-and-safe action.

[Conditions for creep rise]
A condition for determining the creep rise will be described. It is determined that creep has risen when either of the following I) or II) is satisfied (see FIG. 6C).
I) The hydraulic pressure command value for the starting clutch of CVT3 is not less than a predetermined value.
II) The engine 1 is restarted after the automatic stop and a predetermined time has elapsed. These two conditions are determined by the driving force control unit DCU. Even if the braking force holding device RU is released and the braking force disappears, the creep rise will cause the vehicle to move backward on an uphill if the vehicle's inertial force and rolling resistance (plus driving force in the process of increasing) are taken into account. In this state, the driving force is increased to such an extent that it can be suppressed. In addition, the creep rising includes a state in which the driving force is increased to such an extent that the backward driving can be suppressed to a minimum by the driving force that increases even if the vehicle slightly reverses.

The above-described creep rising judgment conditions will be described individually.
I) The condition that “the hydraulic pressure command value of the starting clutch of the CVT 3 is equal to or greater than a predetermined value” is that the reason why the holding of the braking force is canceled if the hydraulic pressure command value of the starting clutch of the CVT 3 is equal to or larger than the predetermined value. This is because it is determined that the driving force is increased to such an extent that the backward movement of the vehicle can be suppressed on the uphill. Moreover, it is because the smooth start without a sudden feeling can be performed even on the downhill. When the hydraulic command value of the starting clutch is greater than or equal to the predetermined value, the hydraulic command value to the linear solenoid valve that controls the hydraulic pressure of the engaging force of the starting clutch is in the weak creep state during the transition from the weak creep state to the strong creep state. It is the point when it increases to a value approximately halfway between the strong creep condition and the strong creep condition.

II) The condition that “the engine 1 restarts after the automatic stop and a predetermined time has elapsed” is that the engine 1 restarts after the automatic stop and the predetermined time elapses. This is because it is determined that the driving force is increased to such an extent that the vehicle can be prevented from moving backward on the slope. Moreover, it is because it is possible to perform a smooth start without sudden feeling on the downhill. The predetermined time starts counting from the time when the engine 1 is actually restarted and the supply of pressure oil to the start clutch of the CVT 3 is started. This is because when the engine 1 is stopped, the hydraulic oil in the hydraulic chamber of the starting clutch of the CVT 3 is missing, so when the engine 1 is started and the supply of pressure oil is started, the invalid stroke (play) of the pressing piston is started. There is. Therefore, the hydraulic pressure command value to the linear solenoid valve of the starting clutch does not match the actual hydraulic pressure value (driving force transmission capacity). As a result, when the driving force increases from the stopped state of the engine 1, it is not possible to determine the start of creep based on the hydraulic pressure command value of the starting clutch of the CVT 3. Therefore, when the engine 1 shifts from the stopped state to the strong creep state, the start of the creep is determined by counting with a timer from the time when the supply of the pressure oil to the starting clutch is started.

[Conditions for issuing a strong creep command]
The conditions for issuing a strong creep command will be described. The strong creep command (F_SCRP) is issued when the condition shown in FIG. 7A or 7B is satisfied, and enters the strong creep state. The first condition for issuing a strong creep command is when either of the following I) or II) is satisfied (see FIG. 7A).
I) (i) Brake switch BSW is OFF or throttle is ON, and position switch PSW is forward (DL) range or (ii) Position switch PSW is reverse (R) range, and (iii) vehicle speed is 5 km / h Must be
II) A vehicle reverse was detected

Alternatively, the second condition for issuing the strong creep command is when either of the following III) or IV) is satisfied (see FIG. 7B).
III) (i) Brake switch BSW is OFF or throttle is ON, and position switch PSW is forward (DL) range, or (ii) position switch PSW is reverse (R) range, and (iii) vehicle speed is 5 km / h Must be
IV) The vehicle speed pulse is input and the vehicle is completely stopped before the vehicle speed pulse is input.

  Incidentally, in the first condition and the second condition where the strong creep command is issued, the condition I) and the condition III) are the same, and the condition II) and the condition IV) are different. Therefore, the description of the condition III) that overlaps the condition of I) is omitted. These conditions are determined by the driving force control unit DCU.

The conditions for issuing the strong creep command will be described individually. First, the conditions (i) to (iii) of I) will be described. Since this content is the same as III), explanation of III) is omitted.
(I) The reason that the condition that “the brake switch BSW is OFF or the throttle is ON and the position switch PSW is in the forward (D / L) range” is that the driver has shifted to the start operation, so that the driver enters the strong creep state. by. That is, the driver intends to start because the position switch PSW is set to the D range or the L range and the brake pedal BP is released or the accelerator pedal is depressed. Therefore, the weak creep state is switched to the strong creep state. When the accelerator pedal is depressed, the driving force transmission capacity after reaching the large driving force transmission capacity is increased to a capacity that can transmit all of the driving force generated by the prime mover (larger state or higher). Is done. However, as for the flag, the strong creep flag (F_SCRPON) continues to be set until another flag is set next. Incidentally, it is more preferable that the brake operation release speed exceeds the threshold value (F_BKTH = 1) instead of the condition that “the brake switch BSW is OFF”. That is, the brake force holding device RU for a vehicle according to the present embodiment holds the brake force on the condition that the brake operation release speed exceeds the threshold value. Therefore, depending on the situation, the brake force may be considerably reduced before the brake operation release speed reaches the threshold value. On the other hand, if a strong creep state is entered at a small brake operation release speed that is less than the threshold value, the vehicle enters a strong creep state with a slight brake operation that is not intended for the driver to start, resulting in vehicle body vibration caused by controlling the driving force with the braking force. Because there are things.

(Ii) The condition that “the position switch PSW is in the reverse (R) range” is for the purpose of smoothly performing creep travel in the R range. That is, when the position switch PSW is switched to the R range, the driver may desire to enter a garage by traveling with a driving force in a strong creep state. Therefore, the weak creep state is switched to the strong creep state.

(Iii) The condition that “the vehicle speed is 5 km / h or less” is based on the reason for determining the strong creep condition during traveling when the vehicle speed exceeds 5 km / h and the strong creep condition when the vehicle speed is 5 km / h or less.

  II) The condition of "vehicle reverse detection" is that the moving force due to the vehicle's own weight exceeds the braking force on a steep uphill and the vehicle starts to move backward, so that the drive force in the strong creep condition suppresses the backward movement. Depending on the reason. In the case of an uphill, the sum of the driving force in a weak creep state (the driving force is zero when the engine 1 is stopped) and the braking force becomes the braking force against the moving force due to the vehicle's own weight. However, the steeper slope increases the moving force due to the vehicle's own weight. Therefore, on a steep uphill, the moving force due to the vehicle's own weight exceeds the sum of the driving force and braking force in the weak creep state, and the vehicle moves backward. Therefore, when the backward movement of the vehicle is detected, the driving force against the uphill is generated by unconditionally changing from the weak creep state to the strong creep state.

  Here, with reference to FIG. 9, a means for detecting the backward movement of the vehicle will be described. For example, helical gears HG (A) and HG (B) are provided on the downstream side of the starting clutch of CVT3. The position where the helical gears HG (A) and HG (B) are provided may be any position that rotates together with the tire. As shown in FIG. 9A, the helical gears HG (A) and HG (B) have helical teeth and are engraved obliquely in the circumferential direction. Therefore, the tooth phase shifts depending on the rotation direction of the tooth in the (i) direction or the (ii) direction. Therefore, electromagnetic pickups P (A) and P (B) are provided on the same axis AX of the helical gears HG (A) and HG (B), respectively, and the tips of the teeth are moved by the electromagnetic pickups P (A) and P (B). To detect. Then, based on the two pulses detected by the electromagnetic pickups P (A) and P (B), the rotation direction is determined from the position of the pulse phase difference. Incidentally, when rotating in the direction (i), as shown in FIG. 9B, the pulse detected by the electromagnetic pickup P (B) is shifted backward from the pulse detected by the electromagnetic pickup P (A). That is, the tip of the tooth of the helical gear HG (A) is detected before the tip of the tooth of the helical gear HG (B). On the other hand, when rotating in the direction (ii), as shown in FIG. 9C, the detected pulse detected by the electromagnetic pickup P (B) is shifted forward from the pulse detected by the electromagnetic pickup P (A). That is, the tip of the tooth of the helical gear HG (A) is detected after the tip of the tooth of the helical gear HG (B). Thus, the rotation direction can be detected by the position of the pulse phase difference. Therefore, for example, when the rotation in the direction (i) is backward movement of the vehicle, if the pulse detected by the electromagnetic pickup P (B) is shifted backward from the pulse detected by the electromagnetic pickup P (A), it is determined that the vehicle is backward. To do. The helical gears HG (A) and HG (B) are used, but any gear may be used as long as the gears of the two gears have a phase difference.

  IV) The condition that “the vehicle speed pulse is input and that the vehicle is completely stopped before the vehicle speed pulse is input” is that the vehicle may move backward (possibly reverse) if the vehicle moves even a little from the complete stop state. ) To make a strong creep and resist the slope. In other words, it is not determined whether the vehicle has moved forward or backward, but the time of movement is determined. In the case of a slope, the sum of the weak creep driving force (the driving force is zero when the engine 1 is stopped) and the braking force becomes the braking force against the moving force due to the vehicle's own weight. However, as the slope becomes steep, the moving force due to its own weight increases. Therefore, on a steep slope, the moving force due to the vehicle's own weight may exceed the sum of the weak creep driving force and the braking force, and the vehicle may move forward (downhill) or reverse (uphill). Therefore, forward or backward movement of the vehicle (that is, movement of the vehicle) is detected, and the driving force against the slope is generated by changing the weak creep state to the strong creep state. First, before the vehicle speed pulse is input, it is detected that the vehicle speed pulse is 0 pulse, and it is detected that the vehicle is completely stopped. Thereafter, if even one vehicle speed pulse is input, it is determined that the vehicle has moved. Even when the vehicle travels in the direction intended by the driver, there is no problem because it is not against the driver's intention to make the driving force a strong creep state.

[Automatic engine start conditions]
A condition for automatically starting the engine 1 after the engine 1 is automatically stopped will be described. When the condition shown in FIG. 8A or FIG. 8B is satisfied, an engine start command (F_ENGON) is issued, and the engine 1 is automatically started. The engine 1 is automatically started by a prime mover stop device. Therefore, the following engine automatic start conditions are determined by the prime mover stop device. Note that the automatic start condition of the engine 1 is determined by the FI / MG ECU 4 and the CVT ECU 6, and if any of the conditions I) to VI) is satisfied by the FI / MG ECU 4, the F_MGSTB becomes 0 and is determined by the CVT ECU 6 to be VII. ) To XI) [or VII] to X] and XII]] is satisfied, F_CVTOK becomes zero. Incidentally, the first condition (condition shown in FIG. 8 (a)) and the second condition (condition shown in FIG. 8 (b)) at which the automatic start condition of the engine 1 is issued are XI determined by the CVTECU 6) vehicle reverse detection XII) Only the vehicle speed pulse input and the condition that the vehicle is completely stopped before the vehicle speed pulse is input are different. Accordingly, only the second condition for generating the automatic start condition of the engine 1 will be described.

  I) The condition that “the depression of the brake pedal BP is released (that is, the brake switch BSW is OFF)” is determined that the start operation of the driver is started by releasing the depression of the brake pedal BP. Because of the reason. That is, in the D range D mode, the driver releases the depression of the brake pedal BP when the start operation is started, so the engine 1 is automatically started. In addition, in the P range and N range, the driver releases the brake pedal BP because it gets off the vehicle. At this time, the driver needs to turn off the ignition switch by the automatic stop of the engine 1. The engine 1 is automatically started so as not to leave the vehicle on the assumption that it is not present. In addition, it is more preferable that the engine 1 is automatically started on the condition that the brake operation release speed exceeds the threshold value (F_BKTH = 1) as in the condition for issuing the strong creep command. As described above, in the case of the vehicle according to the present embodiment, the brake force may be considerably reduced before the brake operation release speed reaches the threshold value. On the other hand, if the engine 1 is automatically started at a small brake operation release speed that is less than the threshold value, the engine 1 is automatically started by a slight brake operation that is not intended for the driver to start.

  II) The condition that “the position switch PSW and the mode switch MSW have been switched to the RD (S mode) / L range” is that the position switch PSW and the mode switch MSW are RD ( The reason for switching to either the S mode or the L range is that it is determined that the driver intends to start immediately. Therefore, after the engine 1 automatically stops in a range other than the R / D (S mode) / L range, the engine 1 is automatically started when the engine 1 is switched to the R / D (S mode) / L range.

  III) The condition that “the battery capacity is equal to or less than a predetermined value” is to prevent the engine 1 from being automatically started when the battery capacity is reduced. In other words, the engine 1 is not automatically stopped unless the battery capacity is greater than or equal to a predetermined value, but the battery capacity may be reduced even after the engine 1 is automatically stopped. 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 that the engine 1 cannot be automatically started when the battery capacity is further reduced.

  IV) The condition that “the electric load is equal to or greater than a predetermined value” is that, for example, when an electric load such as lighting is operating, the battery capacity is rapidly reduced and the engine 1 can be restarted. It is because it is lost. Therefore, the engine 1 is automatically started when the electric load is not less than a predetermined value regardless of the battery capacity.

  V) The condition that “the negative pressure of the master power MP has become smaller than a predetermined threshold” is because the braking force of the brake is reduced when the negative pressure of the master power MP is reduced (approaching atmospheric pressure). by. Therefore, when the negative pressure of the master power MP becomes smaller than a predetermined threshold value, the engine 1 is automatically started.

  This threshold value is appropriately updated every time the vehicle stops based on the map shown in FIG. Specifically, for example, based on the signal detected by the longitudinal acceleration sensor 11 when the vehicle stops, the absolute value of the slope of the road surface on which the vehicle is stopped is calculated, and the slope thus calculated is calculated. The negative pressure threshold value of the master power MP is determined using a map from the absolute value of. By the way, this map has a constant negative pressure threshold β (kPa: kilopascals) when the slope is within the range of 0 to α (°: degree), that is, within the range of the slope regarded as flat. ) And the slope exceeds α, it indicates that the negative pressure threshold is changed to a larger value as the slope increases.

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

  VII) The condition that “FI / MGECU 4 satisfies the automatic start condition of engine 1” is because CVTECU 6 also determines the automatic start condition of engine 1 determined by FI / MGECU 4.

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

  IX) The condition that the depression of the brake pedal BP is released (that is, the brake switch BSW is OFF) is determined that the start operation of the driver is started by releasing the depression of the brake pedal BP. Because it is because. That is, in the D range D mode, the driver releases the depression of the brake pedal BP when the start operation is started, so the engine 1 is automatically started. As described above, it is more preferable to automatically start the engine 1 on the condition that the brake operation release speed exceeds the threshold (F_BKTH = 1).

  X) The condition that “the brake force holding device RU has failed” is that if the brake force holding device RU does not hold the brake force due to a failure, the engine 1 stops (moves forward) on a slope when it stops. That is why. Therefore, when the solenoid valve SV or the like is out of order, the engine 1 is automatically started to create a strong creep state. If a failure is detected in the brake force retaining device RU after the engine 1 has been automatically stopped, the brake force may not be retained when the brake pedal BP is released when starting, so The engine 1 is automatically started when a failure is detected so as to be in a creep state. That is, the vehicle is prevented from retreating in a strong creep condition, and slope start is facilitated. The failure detection of the brake force holding device RU is performed by the failure detection device DU.

  XI) The condition of “vehicle reverse detection” is that the driving force of the engine 1 suppresses the reverse because the moving force due to the weight of the vehicle exceeds the braking force on the steep uphill and the vehicle starts to move backward. by. In the case of uphill, when the engine 1 is stopped, the braking force becomes a braking force against the moving force due to the weight of the vehicle. However, as the slope becomes steep, the moving force due to its own weight increases. Therefore, on a steep uphill, the moving force due to the weight of the vehicle may exceed the braking force, and the vehicle may move backward. Therefore, the reverse of the vehicle is detected, and the driving force against the uphill is generated by unconditionally changing the engine 1 from the stopped state to the strong creep state. Note that the method of detecting the reverse of the vehicle has been described under the condition that a strong creep command is issued, and therefore will be omitted.

  XII) The condition that “the vehicle must be fully stopped before the vehicle speed pulse is input and the vehicle speed pulse is input” is that the vehicle moves backward (may move backward) if the vehicle has moved a little from the fully stopped state. This is because the engine 1 is automatically started and the driving force resists the slope. In other words, it is not determined whether the vehicle has moved forward or backward, but the time of movement is determined. In the case of a slope, when the engine 1 is stopped, only the braking force becomes a braking force against the moving force due to the vehicle's own weight. However, as the slope becomes steep, the moving force due to its own weight increases. Therefore, on a steep slope, the moving force due to the weight of the vehicle may exceed the braking force, and the vehicle may move forward (downhill) or reverse (uphill). Therefore, forward or backward movement of the vehicle (that is, movement of the vehicle) is detected, and the engine 1 is automatically started (a strong creep state is created) to resist the slope. First, before the vehicle speed pulse is input, it is detected that the vehicle speed pulse is 0 pulse, and it is detected that the vehicle is completely stopped. Thereafter, if even one vehicle speed pulse is input, it is determined that the vehicle has moved.

<Control time chart>
Next, what kind of control the vehicle according to this embodiment performs when traveling will be described with reference to FIGS. FIG. 10 is a flowchart of the brake force control in the vehicle brake force holding device according to the present embodiment. FIG. 11 is a control time chart of the vehicle according to the present embodiment. There are two types of vehicles: a case where the vehicle stops on a gentle uphill or flat ground (solid line portion in FIG. 11), and a case where the vehicle stops on a downhill portion (one-dot chain line portion in FIG. 11). The vehicle position switch PSW and mode switch MSW are not changed in the D mode D range.

(Deceleration → Stop)
First, when the vehicle travels (by the way, the vehicle speed> 5 km / h), when the driver releases the depression of the accelerator pedal (that is, when the throttle is turned off), the driving force control unit DCU issues a strong creep command during travel (F_MSCRP). And set to a strong creep condition (F_MSCRPON) during travel (see FIG. 4B). For this reason, the driving force is reduced as compared with the strong creep state (F_SCRPON).

  Further, when the driver releases the depression of the accelerator pedal and depresses the brake pedal BP (when the brake switch BSW is turned on), the braking force increases. When the brake pedal BP is continuously depressed and the vehicle speed reaches 5 km / h, the driving force control unit DCU issues a weak creep command (F_WCRP) to enter a weak creep state (F_WCRPON) (FIG. 4 (a)). reference). At this time, since the strong creep state during driving is changed to the weak creep state, the driver does not receive a strong feeling of deceleration.

  Then, the vehicle stops and the vehicle speed becomes 0 km / h. The driver keeps stepping on the brake pedal BP in order to maintain the vehicle stop state. For this reason, the engine 1 is automatically stopped (see FIG. 5). Here, since the brake force holding device RU does not operate until the brake operation release speed exceeds the threshold value (F_BKTH = 1), the electromagnetic valve SV is in a communication state (see FIG. 3). This state corresponds to S101 in the flowchart of FIG.

  In addition, when the vehicle stopped with such an idling stop is located on a slope (for example, uphill), the reverse of the vehicle due to its own weight is caused by the braking force generated by the driver continuing to step on the brake pedal BP. Although it is suppressed, the negative pressure of the master power MP is gradually lowered by the automatic stop of the engine 1. And when this negative pressure becomes smaller than a predetermined threshold value, the engine 1 is restarted by the above-mentioned prime mover stop device, and a suitable negative pressure is maintained. Since the threshold is appropriately changed according to the slope of the slope as described above, the engine 1 is quickly restarted as the slope becomes tighter (the vehicle needs to be supported with a larger braking force). When the engine is started and the negative pressure is recovered and the inclination is reduced, the timing at which the engine 1 is restarted is delayed. Therefore, the idling stop time can be secured longer as the slope of the slope becomes gentler.

Specifically, the change of the negative pressure threshold is performed based on a flow as shown in FIG.
That is, in step S201, it is always determined whether or not the vehicle is stopped. If the vehicle is stopped (when the vehicle speed is zero) (Yes), the signal from the longitudinal acceleration sensor 11 at that time is Based on this, the inclination of the stop position (road surface) of the vehicle is calculated (step S202). Then, after step S202, a threshold corresponding to the gradient is derived by substituting the calculated gradient in the map shown in FIG. 12 (step S203), and the threshold thus derived is a new value. It is updated as a threshold value (step S204). In addition, after this step S204 or when it is determined in step S201 described above that the vehicle has not stopped (No), this flow is temporarily terminated by proceeding to RETURN, and the original flow that called this flow Returned to Incidentally, in the original flow, the flow of FIG. 13 is repeated at regular intervals (with a short time interval) until a predetermined condition (for example, starting of the engine 1) is satisfied.

[Stop → Start; Loose Uphill (Plane)]
Next, in order to start the vehicle from a gentle uphill or flat ground (see the solid line portion in FIG. 11), the driver starts to release the brake pedal BP by operating the brake (see FIG. 11 (a)). Then, the braking force starts to decrease (see FIG. 11 (d)). At this time, since the solenoid valve SV is not in either the pressure regulation state or the cutoff state (S102), the brake force holding device RU calculates the brake operation release speed (S103). The driver releases the brake pedal BP a little earlier than normal or at a normal speed in order to perform a braking operation on a gentle uphill or flat ground. Accordingly, the brake operation release speed exceeds the threshold in the process of performing the brake operation (S104, see FIG. 11B).

When the brake operation release speed exceeds the threshold value (time t ₀ ), the control unit CU outputs a control current I having a predetermined current value I ₀ and supplies it to the solenoid valve SV (S105, see FIG. 11 (c)). ). As a result, the solenoid valve SV is cut off. Incidentally, as shown in FIG. 11 (d), the braking force is reduced in response to the moment the brake operation amount from the time t _0, since a large brake hydraulic pressure is held in the wheel cylinder WC side, supply This is because, at the current value I ₀ , the solenoid valve SV cannot be shut off, and apparently the communication state is maintained.

By the way, the control unit CU gradually decreases the control current I having the current value I ₀ at a predetermined first decreasing speed at the same time as the control current I having the current value I ₀ is supplied to the solenoid valve SV. (S107). Therefore, the braking force that has decreased in accordance with the amount of brake operation immediately decreases gradually under the pressure regulation state of the solenoid valve SV based on the control current I that gradually decreases at the first decreasing speed (FIG. 11). (See (d)). Note that the vehicle is prevented from moving backward by the braking force that is maintained while gradually decreasing.

When the brake operation of the driver is finished and the brake switch BSW is turned off, the engine 1 is automatically started (see FIG. 11A), and the driving force starts to increase after a predetermined slight time lag (not shown). . Even when the brake switch BSW is turned OFF, the solenoid valve SV is in the pressure regulation state, so that the solenoid valve SV does not enter the communication state (S109, S110). If the driving force increases and it is determined that the creep starts (time t ₁ , S106), the starting driving force is generated to such an extent that the vehicle does not move backward, so the control unit CU controls at the second decreasing speed. The current value of the current I is reduced until the communication state is established (S108, see FIG. 11C). As a result, the braking force acting on the vehicle disappears (see FIG. 11D), and a smooth start of the vehicle without discomfort is realized. By the way, the small value of current indicated by the two-dot chain line in FIG. 11C is for compensating for the operation delay of the solenoid valve SV. Note that when the vehicle is started from a steep uphill, the driver immediately attempts to perform an accelerator operation after releasing the brake pedal BP, so that the brake operation release speed described above increases. Therefore, the brake operation release speed exceeds the threshold earlier than the above case, and the braking force is quickly held accordingly.

[Stop → Start; Downhill] On the other hand, on the downhill (see the one-dot chain line portion in FIG. 11), the brake operation release speed does not reach the threshold value (F_BKTH = 0), so the brake force holding device RU does not operate. Therefore, the braking force depends on the driver's braking operation. Thus, on the downhill, by making the braking force in accordance with the driver's braking operation, it is possible to smoothly advance at a low speed by its own weight. Incidentally, in the case of this vehicle, when the vehicle moves forward (moves), the engine 1 is automatically started (see FIG. 8B).

According to the above, the following effects can be obtained in the present embodiment.
According to the prime mover stopping device of the present embodiment, when the vehicle is stopped on a flat ground, the negative pressure threshold value of the master power MP, which is the starting condition of the engine 1, is smaller than when the vehicle is stopped on a slope. Since it is changed, it takes time for the negative pressure to drop to this reduced threshold, and the idling stop time can be lengthened accordingly. Therefore, the frequency of restarting the engine 1 during idling stop can be reduced, and fuel consumption can be improved. On slopes, the threshold of negative pressure decreases as the slope of the slope decreases, so that it is possible to secure an appropriate braking force according to the slope of the slope and the slope is sufficient with a small braking force. It is possible to improve the fuel consumption by taking a long time until the engine 1 is restarted.

  According to the present embodiment, since the slope of the slope can be satisfactorily detected by the longitudinal acceleration sensor 11 used in other applications, it is not necessary to provide a new sensor for detecting the slope, and the cost can be reduced accordingly. Can be lowered.

  According to the driving force control unit DCU of the present embodiment, the creep driving force can be switched between a small state and a large state according to the depression state of the brake pedal BP under a predetermined condition. The vehicle can be improved and the vehicle can be restarted well.

  According to the prime mover stopping device of the present embodiment, the engine 1 is stopped in a state where the vehicle is stopped and the brake pedal BP is depressed. Therefore, the idling stop is satisfactorily performed without lowering the vehicle even on a slope. be able to. Further, when the brake pedal BP is released from this state, the engine 1 is started, so that the vehicle can be restarted satisfactorily.

  According to the vehicle according to the present embodiment, the vehicle can be smoothly started regardless of the situation, for example, there is no retreat of the vehicle on the uphill and the vehicle can smoothly advance at a slow speed due to its own weight on the downhill. When the solenoid valve is a proportional solenoid valve, when the brake fluid pressure on the master cylinder side is higher than the current value of the set control current, the solenoid valve cannot be shut off and the communication state is Maintained. Therefore, on the downhill, even if the control unit supplies a certain large current value to the solenoid valve, the brake operation is performed with a brake fluid pressure higher than the brake fluid pressure that can shut the solenoid valve with this current value. In this case, the presence of the solenoid valve does not hinder the driver's brake operation. Further, if it is not necessary to gradually reduce the braking force by the electromagnetic valve, a general electromagnetic valve that can create a normal communication state and a cutoff state can also be used.

In addition, this invention is implemented in various forms, without being limited to the said embodiment.
In the above embodiment, the longitudinal acceleration sensor 11 is used as means for detecting the inclination, but the present invention is not limited to this. For example, a vehicle height sensor, navigation information, or a fuel tank level sensor is used. Also good. When the vehicle height sensor is used to calculate the inclination, the initial setting values (for example, the vehicle height of the front wheels and the vehicle height of the rear wheels when the vehicle is stopped on a flat ground) and the current detection values (for example, uphill) When the vehicle is stopped, the center of gravity of the vehicle apparently moves to the rear side, so that the front wheel height increases and the rear wheel height decreases). The inclination can be detected by referring to the wheel base indicating the distance to the rear wheel. Further, when the navigation information is used to calculate the slope, the slope information of the vehicle stop position can be acquired by setting contour lines or the like on the map. Furthermore, when the liquid level sensor of the fuel tank is used for the calculation of the inclination, for example, the respective liquid level is detected by two liquid level sensors arranged at predetermined intervals in the vehicle front-rear direction. By calculating the inclination of the liquid level based on the liquid level information, the slope of the slope can be calculated.

  In the present embodiment, the engine 1 is automatically stopped when the vehicle is stopped. However, the present invention is not limited to this, and the engine 1 is automatically stopped when a predetermined speed at which the vehicle is likely to stop is reached. Also good.

1 is a system configuration diagram of a vehicle according to an embodiment. It is a block diagram of the brake force holding | maintenance apparatus of the vehicle which concerns on this embodiment. It is the control logic which hold | maintains the brake force of a brake force holding | maintenance apparatus. It is a figure which shows the control logic of a driving force control apparatus, (a) is the control logic which makes a weak creep state, (b) is the control logic which makes a strong creep state at the time of driving, (c) is the control logic which makes a medium creep state It is. This is control logic for automatically stopping the engine of the prime mover stopping device. It is a figure which shows the control logic of a brake force holding | maintenance apparatus, (a) is the control logic (1st reduction speed-> 2nd reduction speed-> which cancels | releases holding | maintenance of brake force when starting drive force produced in the vehicle itself. (Communication state), (b) is a control logic for releasing the holding of the braking force from the viewpoint of fail-and-safe (first reduction speed → communication state), and (c) is a control logic for determining the start of creep. It is a figure which shows the control logic of a driving force control apparatus, (a) is the control logic (vehicle reverse detection version) which makes a strong creep state, (b) is the control logic (vehicle movement detection version) which makes a strong creep state. . It is a figure which shows the control logic of a motor | power_engine stop apparatus, (a) is the control logic (vehicle reverse detection version) which starts an engine automatically, (b) is the control logic (vehicle movement detection version) which starts an engine automatically. It is an example of a vehicle reverse detection method, (a) is a block diagram of vehicle reverse detection, (b) is a pulse phase of (i) direction rotation of (a) figure, (c) is (ii) of (a) figure. It is the pulse phase of direction rotation. It is a flowchart of brake force control in the brake force holding device for a vehicle according to the present embodiment. It is a control time chart of the vehicle concerning this embodiment. It is a map for determining the negative pressure threshold value of the master power from the absolute value of the inclination. It is a flowchart which shows the flow for changing the threshold value of a negative pressure.

Explanation of symbols

1 Engine 4 FI / MG ECU (Motor Stop Device)
11 Longitudinal Acceleration Sensor BP Brake Pedal BSW Brake Switch CU Control Unit DCU Driving Force Control Device MC Master Cylinder MP Master Power RU Brake Force Holding Device

Claims (5)

It is mounted on a vehicle including a brake booster that generates a negative pressure by driving an engine to increase a braking force, an engine stop unit that stops the engine, and an engine start unit that starts the engine,
An engine stop instruction unit that instructs the engine stop means to stop the engine according to a depression state of a brake pedal when the vehicle speed is equal to or lower than a predetermined value;
An engine control device comprising: an engine start instruction unit that instructs the engine start means to start the engine when at least a negative pressure of the brake booster becomes smaller than a predetermined threshold value;
The engine control device includes an inclination determination means for determining whether or not the stop position of the vehicle is flat.
The engine control apparatus according to claim 1, wherein the engine start instruction unit is configured to make the predetermined threshold value smaller when the determination by the inclination determination means is flat than when the inclination is not flat. The engine control device according to claim 1,
When the vehicle stop position is a slope, the inclination determination means calculates the inclination,
The engine control apparatus according to claim 1, wherein the engine start instruction unit is configured to decrease the predetermined threshold as the slope is smaller. The engine control device according to claim 1 or 2,
The engine control device according to claim 1, wherein the inclination determination unit includes a longitudinal acceleration sensor, a vehicle height sensor, navigation information, or a fuel tank level sensor. It is an engine control device given in any 1 paragraph of Claims 1-3,
The engine control device includes:
Under the condition that the engine is idling and the vehicle speed is equal to or less than a predetermined value, when the brake pedal is depressed, the creep driving force is switched to a preset small state, and the brake is An engine control device mounted on a vehicle further including a driving force control device that switches the driving force of the creep to a preset large state when the pedal is released. It is an engine control device given in any 1 paragraph of Claims 1-3,
The engine control device includes:
When the vehicle is stopped, the engine is stopped on the condition that the brake pedal is depressed and the driving force is in the preset small state, and the stopped engine is started on the condition that the depression of the brake pedal is released. An engine control device.

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