JP2008298016A - Vehicle control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle control technology capable of securing the stop of a vehicle and the operation of a parking brake even if a battery fails. <P>SOLUTION: An ECB (Electronically Controlled Brake) device 40 applies or releases a parking brake by the drive of a motor 47. The ECB device 34 controls a braking force applied to a vehicle based on an operation input by a driver. A battery 24 supplies electric power to an EPB (Electronic Parking Brake) device 40 and the ECB device 34. A capacitor 26 is for use in the back-up of the battery 24 and commonly used for the EPB device 40 and the ECB device 34. A vehicle speed restriction demand part 14 determines whether electric power necessary for stopping the travelling vehicle by the ECG device 34 and operating the parking brake by the EPB device 40 is charged to the capacitor 26 or not, and requests an engine ECU 50 to restrict vehicle speed if it is determined that the electric power is not charged. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates generally to electric parking brakes, and more particularly to control techniques for ensuring the operation of an electric parking brake.

  Conventionally, a hydraulic pressure control device for applying a braking force to wheels provided in a vehicle is known. This device includes an actuator including a plurality of pairs of electromagnetic control valves used for increasing or decreasing the pressure of a wheel cylinder provided on each of a plurality of wheels, and an electronic control unit for controlling the actuator. According to this apparatus, the amount of operation of the brake pedal by the driver is measured by a sensor or the like, converted into an electric signal, and provided to the electronic control unit. The electromagnetic control valve for pressure increase or pressure reduction is controlled by the electronic control unit, and the working fluid stored in the accumulator in a predetermined pressure state is independently and optimally provided to the four wheel wheel cylinders of the vehicle to control the braking force. . The brake that controls the braking force by replacing the operation input by the driver with an electric signal and providing the working fluid from the pressure accumulation source is referred to as an electronically controlled brake (ECB) system.

  In addition to the foot brake as described above, a parking brake is mounted on the vehicle. The simplest type of parking brake is to drive a wire by pulling an operation lever to operate a brake pad and brake a wheel. However, in recent years, an electric parking brake (EPB) that is operated or released by driving an electric motor by switching an operation switch or the like by a driver is also employed. In this electric parking brake, when the driver sets the operation switch to the operating side, the electric motor is driven and the wire is caught to operate the parking brake, and when the operation switch is set to the releasing side, the wire is rewound. The parking brake is released.

The electric parking brake as described above may not be able to operate the parking brake when the battery voltage is lowered. Thus, for example, Patent Document 1 discloses an improved parking brake that can be operated even when an energy source fails.
JP 2004-359224 A

  Recently, there are also vehicles equipped with both the above-mentioned ECB and EPB. In such a vehicle, if the battery has some trouble while the vehicle is running and power cannot be supplied, both the foot brake and the parking brake may not be operated. For this reason, a capacitor is usually mounted as an auxiliary power source. The capacitor is discharged when the ignition switch is turned off, and charged by the alternator when the ignition switch is turned on.

  Usually, a capacitor is configured to be gradually charged because it deteriorates and shortens its life when rapidly charged. Therefore, when the vehicle travels at a high speed immediately after the ignition switch is turned on, there is a possibility that the power necessary for braking the vehicle and the power necessary for operating the parking brake are not charged in the capacitor.

  The present invention has been made in view of such a situation, and an object of the present invention is to stop the vehicle and operate the parking brake even when the battery breaks down in a vehicle sharing an auxiliary power source between the foot brake device and the parking brake device. It is to provide a vehicle control technology that is secured.

  One embodiment of the present invention is a vehicle control system. The system includes an electric parking brake device that activates or releases a parking brake by driving a motor, an electronic control brake device that controls a braking force applied to a vehicle based on an operation input by a driver, the electric parking brake device, and the electric parking brake device. A battery that supplies electric power to the electronically controlled brake device, an auxiliary power source that is shared by the electric parking brake device and the electronically controlled brake device, and the vehicle that is running when the battery fails, the electronically controlled brake device It is determined whether the electric power required for operating the parking brake by the electric parking brake device is charged in the auxiliary power source, and the vehicle speed is limited when it is determined that the electric power is not charged. A vehicle speed limit requesting unit that requests the same.

  According to this aspect, since the running vehicle is braked and stopped, the maximum speed of the vehicle is limited until the amount of power necessary for operating the parking brake is stored in the auxiliary power source. Even in the event of a failure, the vehicle can be reliably stopped and the parking brake can be operated.

  A charge rate calculation unit for calculating the charge rate of the auxiliary power source may be further provided, and the vehicle speed limit requesting unit holds in advance a lower limit charge rate necessary for stopping the running vehicle and operating the parking brake. If the charging rate of the auxiliary power source is lower than the lower limit charging rate, it may be requested to limit the vehicle speed.

  The vehicle speed restriction requesting unit may release the restriction on the vehicle speed when the charging rate of the auxiliary power source exceeds a predetermined value. According to this, after the ignition switch is turned on, if the vehicle continues to run and the auxiliary power supply is sufficiently charged, the vehicle speed restriction is released and free running is possible.

  You may further provide the vehicle weight measurement part which detects the weight of a vehicle. The vehicle speed restriction requesting unit may increase the lower limit charging rate as the vehicle weight increases. According to this, it is considered that the electric power necessary for braking and stopping the vehicle increases as the vehicle weight increases, so the lower limit charging rate is set higher.

  The vehicle speed restriction requesting unit may set an allowable maximum speed of the vehicle according to a charging rate of the auxiliary power source. According to this, even when the charging rate of the auxiliary power source is below the lower limit charging rate, the upper limit of the vehicle speed at which the vehicle can be stopped is different depending on the charging rate, so the allowable maximum speed is set according to the charging rate To do.

  According to the present invention, after braking and stopping the running vehicle, the maximum speed of the vehicle is limited until the amount of power necessary for operating the parking brake is stored in the auxiliary power source. Even when the battery fails, the vehicle can be stopped reliably and the parking brake can be operated.

Embodiment 1 FIG.
FIG. 1 is an overall configuration diagram of a vehicle control system 100 according to an embodiment of the present invention. The vehicle control system 100 replaces an operation amount of the brake pedal 32 by the driver with an electric signal, and provides an operating fluid from a pressure accumulation source (not shown) to apply a braking force to the wheels (hereinafter referred to as an electronic control brake device). , Referred to as “ECB device”) 34 and an electric parking brake device (hereinafter referred to as “EPB device”) 40 used when the vehicle is parked.

  The EPB device 40 includes an electric motor 47, gears 44 and 46, and a joint 42. A wire (not shown) is fixed to the tip of the joint 42, and the tip of the wire is connected to a drum brake (not shown) provided on the rear wheel of the vehicle, for example. When the electric motor 47 is driven in accordance with an operation of a parking brake switch provided in the passenger compartment and the gear 46 is rotated in the right direction in the figure, the joint 42 engaged with the gear 46 moves upward. The wire is pulled up and the drum brake is activated to generate braking force on the rear wheels. When the electric motor 47 rotates the gear 46 in the left direction according to the operation of the parking brake switch, the joint 42 engaged with the gear 46 moves downward to loosen the wire, the drum brake is released, and the non- A braking state is entered.

  Another gear 44 is also engaged with the joint 42. The gear 44 has a role of defining the movable range of the joint 42 and maintaining the position of the joint 42 even after the electric motor 47 is stopped. For this reason, the parking brake is not released even if the electric motor 47 is not operated.

  Further, a mark 45 indicating the position of the joint is attached to the gear 44. By monitoring this mark by the sensor 48, the operation and release of the parking brake can be confirmed.

  The brake ECU 30 operates the ECB device 34 to control the braking force applied to the four wheels provided in the vehicle. A predetermined brake control flow is stored in the ROM of the brake ECU 30. When the driver operates the brake pedal 32 to issue a braking request, the brake ECU 30 calculates a required braking force to be generated by the ECB device 34. Further, the target hydraulic pressure of the wheel cylinder provided for each wheel is calculated based on the calculated required braking force. The brake ECU 30 determines the value of the current supplied to the control valve that controls the flow of the brake fluid to the wheel cylinder so that the wheel cylinder pressure becomes the target hydraulic pressure. As a result, brake fluid is supplied to each wheel cylinder, and braking force is applied to the wheels.

  Since the configurations of the ECB device 34 and the EPB device 40 are well known, further description thereof is omitted in this specification.

  The engine ECU 50 controls an engine (not shown) that drives a vehicle (not shown). The engine ECU 50 calculates the target engine speed according to the operation of the accelerator pedal 64 by the driver, that is, according to the accelerator opening instruction. Then, the electronic throttle 54, the igniter 56, and the injector 58 are appropriately controlled so that the engine speed measured by the speed sensor 60 becomes a target value. Since such engine control is well known, further description is omitted in this specification.

  Inclination sensor 62 detects the inclination of the vehicle (not shown) and provides it to engine ECU 50. The load weight sensor 22 detects the weight of a load such as an occupant or a baggage and supplies it to the power management ECU 20. The load weight sensor 22 may be, for example, a surface pressure sensor embedded in a seat surface of a seat or a floor surface of a cargo compartment, or a distance sensor that measures a distance between a vehicle body and a road surface.

  The power management ECU 20 controls the EPB device 40 and also monitors the power system that drives the ECB device 34 and the EPB device 40. The vehicle control system 100 includes a battery 24 and a backup capacitor 26 as power sources.

  The capacitor 26 serves as an auxiliary power source when the battery 24 fails, and is configured to be able to brake the vehicle and operate the parking brake using the power of the capacitor. The capacitor 26 is shared by the ECB device 34 and the EPB device 40. Therefore, when a battery failure occurs, the capacitor 26 needs to cover both powers.

  The capacitor 26 is configured to be discharged while the ignition switch 28 is turned off in order to extend the life and improve safety. When the ignition switch 28 is turned on and the vehicle starts running, the capacitor 26 is gradually charged by the electric power generated by an alternator (not shown). Charging is performed gradually over several minutes to extend the life.

  After the ignition switch 28 is turned on, if a failure or disconnection of the battery 24 occurs when the capacitor 26 is not sufficiently charged, the power required to stop the vehicle and operate the parking brake is insufficient. Can happen. Then, even if the driver can stop the vehicle, the parking brake cannot be operated. In particular, when the stop position of the vehicle is a slope, there is a possibility that the vehicle cannot be dismounted.

  Thus, the power management ECU 20 limits the maximum speed of the vehicle until the capacitor 26 is sufficiently charged.

The power management ECU 20 includes a charging rate calculation unit 12 and a vehicle speed limit requesting unit 14.
The charging rate calculation unit 12 is configured to measure the voltage of the capacitor 26 and calculate the charging rate of the capacitor 26. When the vehicle speed limit requesting unit 14 determines that the capacitor 26 is not sufficiently charged, the vehicle speed limit requesting unit 14 sets a flag LMT for limiting the maximum speed of the vehicle to ON. The target speed setting unit 52 in the engine ECU 50 controls the electronic throttle 54, the igniter 56, and the injector 58 to limit the engine speed while the flag LMT is ON regardless of the depression amount of the accelerator pedal 64. Then, limit the vehicle speed.

  The vehicle speed limit requesting unit 14 sets the flag LMT to OFF when the charging rate of the capacitor 26 exceeds a predetermined threshold value. In response to this, the engine ECU 50 controls the engine speed according to the amount of depression of the accelerator pedal 64.

  Note that the charging rate calculation unit 12, the vehicle speed limit requesting unit 14, and the target rotation speed setting unit 52 in FIG. 1 can be realized in hardware by elements and electronic circuits such as a CPU and a memory of a computer. Is realized by a computer program or the like, but here, it is depicted as a functional block realized by their cooperation. Accordingly, those skilled in the art will understand that these can be realized in various forms by a combination of hardware and software.

FIG. 2 is a graph for converting the charging rate of the capacitor from the capacitor voltage. In the figure, the horizontal axis indicates the capacitor voltage, and the vertical axis indicates the charging rate. V _min and V _max indicate the minimum and maximum values of the capacitor voltage at which this graph can be used. The charging rate calculation unit 12 holds a table corresponding to this graph, and may obtain a charging rate according to the capacitor voltage obtained by referring to this table, or a calculation formula corresponding to this graph may be obtained. The charging rate may be calculated according to the acquired capacitor voltage.

FIG. 3 is a flowchart for determining whether or not the vehicle speed restriction is necessary.
When the ignition switch 28 is turned on (Y in S10), the charging rate calculation unit 12 measures the voltage of the capacitor 26, and calculates the capacitor charging rate SOC based on this (S12). The vehicle speed limit requesting unit 14 holds the lower limit charging rate SOCk of the capacitor corresponding to the electric power necessary for braking the vehicle from running at a standard speed (for example, 70 km / h) and stopping the vehicle and operating the parking brake. This is compared with the charge rate SOC (S14). If the SOC is less than SOCk (Y in S14), it is determined that sufficient electric power is not stored in the capacitor 26, and a flag LMT for limiting the maximum vehicle speed is turned ON (S16). If the SOC is equal to or higher than SOCk (N in S14), it is determined that there is no need to limit the maximum vehicle speed, and the flag LMT is turned off (S18).

FIG. 4 is a flowchart for controlling the engine speed based on the vehicle speed restriction request.
The target rotation speed setting unit 52 determines whether or not the flag LMT is ON (S30). If LMT = OFF (N in S30), this flowchart ends. When LMT = ON (Y in S30), it is determined from the measured value of the vehicle speed sensor 38 whether or not the current vehicle speed is equal to or higher than a predetermined value SPDLIM (S32). This SPDLIM is a threshold value for eliminating the case where the vehicle is traveling at a very low speed so that it is not necessary to consider the power required for braking, and is set to about 10 km / h, for example. If the vehicle speed is less than SPDLIM (N in S32), this flowchart ends. If the vehicle speed is equal to or higher than SPDLIM (Y in S32), the target engine speed setting unit 52 sets NELIM as the target engine speed (S34).

  NELIM is set to a rotational speed corresponding to the vehicle speed at which the parking brake can be operated by reliably stopping the vehicle even when the charging rate of the capacitor 26 is low. Note that NELIM is preferably changed in value according to the charging rate of the capacitor 26. For example, it is preferable to decrease NELIM as the charging rate decreases so that the vehicle speed is 50 km / h when the charging rate is 50% and the vehicle speed is 30 km / h when the charging rate is 30%. However, for simplicity, NELIM may be set to a rotational speed corresponding to a constant value, for example, 30 km / h.

  The target rotation speed setting unit 52 compares the angle detected by the tilt sensor 62 with a predetermined threshold value and determines whether or not the vehicle is traveling on a downhill (S36). If the vehicle is not traveling downhill (N in S36), the remaining processing is skipped. If the vehicle is traveling on a downhill (Y in S36), it is determined whether or not the current engine speed is smaller than the NELIM set in S34 (S38). If it is smaller than NELIM (Y in S38), the target engine speed is set to the idle speed IDLE (S40). This process is performed to set the target engine speed to a smaller value when the vehicle is traveling downhill and the engine speed is small.

  As described above, according to the first embodiment, after the running vehicle is braked and stopped, the maximum speed of the vehicle is limited until the electric energy necessary for operating the parking brake is stored in the capacitor. As a result, the parking brake can be operated by reliably stopping the vehicle even in the event of a battery failure.

Embodiment 2. FIG.
In the first embodiment, the lower limit charging rate SOCk for determining whether or not to limit the maximum vehicle speed is assumed to be constant. However, in reality, the more people and luggage are loaded on the vehicle, that is, the greater the vehicle weight, the greater the amount of electric power required to brake the vehicle even when traveling at the same speed. Therefore, in the second embodiment, the vehicle weight is considered when setting the lower limit charging rate SOCk.

FIG. 5 is a flowchart for determining whether or not the vehicle speed restriction is necessary according to the second embodiment.
Whether the ignition switch 28 when turned on (S50 of Y), vehicle weight obtaining unit power management in ECU 20 (not shown), a vehicle speed based on the detected value of the vehicle speed sensor 38 is below a predetermined value V _min Is determined (S52). When the vehicle speed is lower than V _min (Y in S52), the vehicle weight acquisition unit converts the detection value of the load weight sensor 22 into the load weight, and adds the weight of the vehicle itself to calculate the vehicle weight WGT (S54). . Since the vehicle vibration needs to be small in order to measure an accurate value with the load weight sensor 22, the determination of S52 is made to measure the load weight when traveling at a low speed. When the vehicle speed is equal to or higher than V _min (N in S52), a predetermined standard vehicle weight is used (S53).

Subsequently, the vehicle weight acquisition unit determines whether or not the vehicle weight WGT is equal to or lower than the lower limit value WGT _min (S56). If the vehicle weight WGT is equal to or lower than the lower limit value (Y in S56), the vehicle weight WGT is determined as the lower limit value WGT. _Reset to _min (S58). Further, it is determined whether or not the vehicle weight WGT is equal to or greater than the upper limit value WGT _max (S60). If the vehicle weight WGT is equal to or greater than the upper limit value (Y in S60), the vehicle weight WGT is reset to the upper limit value WGT _max (S62). When the vehicle weight WGT is between the upper limit value and the lower limit value, the values are used as they are (N in S56, N in S60).

  The charging rate calculation unit 12 measures the voltage of the capacitor 26 and calculates the capacitor charging rate SOC based on the voltage (S64). The vehicle speed restriction request unit 14 calculates a lower limit charging rate SOCk for determining whether or not to limit the maximum speed of the vehicle (S66). The SOCk is calculated according to a predetermined calculation formula according to the vehicle weight WGT. In general, the greater the vehicle weight WGT, the more power is required for braking the vehicle, so the lower limit charge rate SOCk also increases, and the lower the vehicle weight WGT, the less power required for braking, the lower limit charge rate. The value of SOCk is also reduced.

The charge rate calculation unit 12 determines whether or not the calculated lower limit charge rate SOCk is equal to or lower than the lower limit value SOCk _min (S68). If the calculated lower limit charge rate SOCk is equal to or lower than the lower limit value (Y in S68), the lower limit charge rate SOCk is determined as SOCk. _Reset to _min (S70). Further, it is determined whether or not the lower limit charge rate SOCk is equal to or higher than the upper limit value SOCk _max (S72). If the lower limit charge rate SOCk is equal to or higher than the upper limit value (Y in S72), the lower limit charge rate SOCk is reset to SOCk _max (S74). When the lower limit charging rate SOCk is between the upper limit value and the lower limit value, the values are used as they are (N in S68, N in S72).

  The vehicle speed limit requesting unit 14 compares the lower limit charging rate SOCk set in S66 to S74 with the actual charging rate SOC of the capacitor 26 (S76). If the SOC is less than SOCk (Y in S76), it is determined that sufficient electric power is not stored in the capacitor 26, and a flag LMT for limiting the maximum vehicle speed is turned ON (S78). If the SOC is equal to or higher than SOCk (N in S76), it is determined that there is no need to limit the maximum vehicle speed, and the flag LMT is turned off (S80). Hereinafter, the processing in the target rotation speed setting unit 52 is the same as that shown in FIG.

  The present invention has been described based on some embodiments. These embodiments are merely examples, and modifications such as arbitrary combinations of the embodiments, each component of the embodiments, and any combination of the processing processes are also within the scope of the present invention. It will be understood by those skilled in the art.

  The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added based on the knowledge of those skilled in the art. The configuration shown in each drawing is for explaining an example, and can be appropriately changed as long as the configuration can achieve the same function.

  In the embodiment, the amount of electric power necessary for the deceleration of the vehicle and the operation of the parking brake after stopping is taken into account, but in addition to this, the amount of electric power required for the shift change of the transmission is taken into account and the capacitor is sufficiently charged. You may make it determine whether it exists.

  In addition, the capacitor is gradually charged by the alternator while the vehicle continues to travel, so the total of the capacitor charging rate immediately after the ignition switch is turned on and the charging rate stored during traveling is estimated, and the lower limit charging rate is You may make it compare. By doing so, the timing for releasing the vehicle speed limit can be advanced.

1 is an overall configuration diagram of a vehicle control system according to an embodiment of the present invention. It is a graph for converting the charge rate of a capacitor from a capacitor voltage. It is a flowchart which determines the necessity of vehicle speed restriction | limiting. It is a flowchart which controls an engine speed based on a vehicle speed restriction request. 7 is a flowchart for determining whether or not a vehicle speed limit is required according to the second embodiment.

Explanation of symbols

  12 charge rate calculation unit, 14 vehicle speed limit request unit, 20 power management ECU, 22 load weight sensor, 24 battery, 26 capacitor, 28 ignition switch, 30 brake ECU, 34 ECB device, 40 EPB device, 50 engine ECU, 52 target A rotational speed setting unit, 62 an inclination sensor, 100 a vehicle control system.

Claims (5)

An electric parking brake device for operating or releasing the parking brake by driving a motor;
An electronically controlled brake device that controls a braking force applied to the vehicle based on an operation input by the driver;
A battery for supplying electric power to the electric parking brake device and the electronically controlled brake device;
An auxiliary power source shared by the electric parking brake device and the electronically controlled brake device;
Whether or not the auxiliary power supply is charged with electric power necessary for stopping the running vehicle by the electronic control brake device and operating the parking brake by the electric parking brake device when a failure occurs in the battery A vehicle speed limit requesting unit that requests to limit the vehicle speed when it is determined that the battery is not charged,
A vehicle control system comprising: A charge rate calculator for calculating a charge rate of the auxiliary power supply;
The vehicle speed limit requesting unit holds a lower limit charging rate necessary for stopping the running vehicle and operating the parking brake in advance, and limits the vehicle speed when the charging rate of the auxiliary power source is lower than the lower limit charging rate. The vehicle control system according to claim 1, wherein the vehicle control system is requested to do so.   3. The vehicle control system according to claim 2, wherein the vehicle speed restriction request unit releases the restriction on the vehicle speed when a charging rate of the auxiliary power source exceeds a predetermined value. A vehicle weight measuring unit for detecting the weight of the vehicle;
The vehicle control system according to claim 2 or 3, wherein the vehicle speed restriction request unit increases the lower limit charging rate as the vehicle weight increases.   5. The vehicle control system according to claim 1, wherein the vehicle speed limit requesting unit sets an allowable maximum speed of the vehicle according to a charging rate of the auxiliary power source.

Images