JP2007320368A - Braking force control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a braking force control device capable of securing the negative pressure required to make a brake booster function in an opening failure of a throttle valve. <P>SOLUTION: An ECU stores the air load ratio characteristic as a characteristic of the air load ratio KL of an engine in relation to the negative pressure inside of an intake pipe, the air flow characteristic as a characteristic of the air flow Q to be supplied to the engine in relation to the opening of the throttle valve, and displacement of the engine. In order to make the brake booster function when an opening failure of the throttle valve is detected, the ECU specifies the air load ratio KL corresponding to the negative pressure inside of the intake pipe to be required to obtain the necessary negative pressure to be required for the brake booster on the air load ratio characteristic (S21), specifies the air flow Q corresponding to the opening of the throttle valve on the air flow characteristic (S22), and computes ((air flow Q/air load ratio KL)/displacement) × unit equivalence (S23) as the engine speed required to obtain the negative pressure necessary for the brake booster. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a braking force control device that controls the braking force of a vehicle when a throttle valve is open.

As a conventional braking force control device, a throttle valve open failure is detected, a vehicle deceleration state is detected, and when the throttle valve open failure and deceleration state are detected, the shift pattern of the automatic transmission is changed to the low gear side. In some cases, a deceleration force close to the driver's intention is obtained even when the brake action is deteriorated due to the throttle valve opening failure (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 11-159604

  However, the conventional braking force control device has a problem in that the negative pressure required for the brake booster functioning by the negative pressure generated in the intake pipe as the engine rotates cannot be guaranteed when the throttle valve opens.

  The present invention has been made to solve the conventional problems, and an object of the present invention is to provide a braking force control device capable of guaranteeing a negative pressure required to make a brake booster function when a throttle valve is open. And

  The braking force control device of the present invention is a braking force control device that controls the braking force of a vehicle provided with a brake booster that functions by a negative pressure generated in the intake pipe as the engine rotates. Brake booster required negative pressure storage means for storing necessary brake booster required negative pressure, open failure detection means for detecting an open failure of the throttle valve, and when the open failure is detected by the open failure detection means, Required engine speed calculating means for calculating a required engine speed that is the engine speed required for obtaining the required brake booster negative pressure, and an engine for adjusting the engine speed so as to exceed the required engine speed And a rotational speed adjusting means.

  With this configuration, the braking force control apparatus according to the present invention is necessary for functioning the brake booster when the throttle valve is open, in order to adjust the engine speed so as to obtain the negative pressure necessary to function the brake booster. Negative pressure can be guaranteed.

  The braking force control apparatus according to the present invention includes an air load factor characteristic that is a characteristic of an air load factor of the engine with respect to a negative pressure in the intake pipe, and an air flow rate supplied to the engine with respect to an opening of the throttle valve. Characteristic storage means for storing an air flow characteristic that is a characteristic and a displacement of the engine, and the required engine speed calculating means is configured to adjust the negative pressure in the intake pipe required to obtain the negative pressure required for the brake booster. The required engine speed is calculated based on the air load factor corresponding to the air load factor characteristic, the air flow rate corresponding to the air flow characteristic to the opening of the throttle valve, and the exhaust amount. It may be.

  With this configuration, the braking force control apparatus of the present invention can calculate the engine speed required to obtain the negative pressure necessary to make the brake booster function.

  The braking force control apparatus according to the present invention further includes a rotation speed determination means for determining whether or not the engine rotation speed detected by an engine rotation speed sensor provided in the engine is lower than the required engine rotation speed. And when the engine speed determining means determines that the engine speed detected by the engine speed sensor is below the required engine speed, the engine speed is You may make it set the gear of the transmission which becomes more than the said required engine speed.

  With this configuration, the braking force control apparatus according to the present invention sets a gear that can obtain the engine speed required to obtain the negative pressure required to make the brake booster function. Can guarantee the function.

  Further, the braking force control device of the present invention provides a turbine rotational speed characteristic that is a characteristic of a rotational speed of a turbine provided on the transmission side of a torque converter that converts torque transmitted from the engine to the transmission with respect to a vehicle speed. Turbine rotational speed characteristic storage means for storing each gear of the transmission is provided, and the engine rotational speed adjustment means corresponds to the current engine speed on the turbine rotational speed characteristic, and the turbine rotational speed corresponds to the required engine rotational speed. You may make it select as a gear which sets the said gear which becomes more than the rotation speed of the said turbine.

  With this configuration, the braking force control apparatus of the present invention can increase the engine speed to a required engine speed or higher.

  The braking force control method of the present invention is a braking force control method for controlling the braking force of a vehicle provided with a brake booster that functions by a negative pressure generated in the intake pipe as the engine rotates. The brake booster necessary negative pressure required for the operation is stored in a storage medium, and an open failure detection means detects an open failure of the throttle valve, and a required engine speed calculation means includes the open failure. A required engine speed calculating step for calculating a required engine speed which is the engine speed required to obtain the brake booster required negative pressure when the open failure is detected in the detecting step; and engine speed adjustment An engine speed adjusting step for adjusting the engine speed so that the means exceeds the required engine speed The has.

  By this method, the engine speed is adjusted so as to obtain the negative pressure necessary for the brake booster to function, so that it is possible to guarantee the negative pressure necessary for the brake booster to function when the throttle valve opens. .

  The braking force control method according to the present invention includes an air load factor characteristic that is a characteristic of an air load factor of the engine with respect to a negative pressure in the intake pipe, and an air flow rate supplied to the engine with respect to an opening of the throttle valve. The air flow rate characteristic and the engine displacement are stored in a storage medium, and in the required engine speed calculating step, the required engine speed calculating means obtains the brake booster required negative pressure. Based on the air load factor corresponding to the negative pressure in the intake pipe on the air load factor characteristic, the air flow rate corresponding to the air flow rate characteristic to the opening of the throttle valve, and the exhaust amount, The required engine speed may be calculated.

  By this method, it is possible to calculate the engine speed required to obtain the negative pressure necessary to make the brake booster function.

  In the braking force control method of the present invention, the engine speed determining means determines whether or not the engine speed detected by an engine speed sensor provided in the engine is lower than the required engine speed. When the engine speed adjustment step determines that the engine speed detected by the engine speed sensor is lower than the required engine speed in the engine speed determination step. The engine speed adjusting means may set a transmission gear in which the engine speed is equal to or higher than the required engine speed.

  By this method, the gear that can obtain the engine speed required to obtain the negative pressure required to make the brake booster function is set, so that the function of the brake booster can be ensured when the throttle valve opens.

  In the braking force control method of the present invention, the turbine rotational speed characteristic, which is a characteristic of the rotational speed of the turbine provided on the transmission side of the torque converter for converting the torque transmitted from the engine to the transmission, with respect to the vehicle speed is described above. The transmission speed is stored in a storage medium for each gear of the transmission, and in the engine rotation speed adjustment step, the engine rotation speed adjustment means requires the rotation speed of the turbine corresponding to the current vehicle speed in the turbine rotation speed characteristics. You may make it select as a gear which sets the said gear which becomes more than the rotation speed of the said turbine corresponding to engine rotation speed.

  By this method, the engine speed can be made higher than the required engine speed.

  The present invention can provide a braking force control device capable of guaranteeing a negative pressure necessary for a brake booster to function when a throttle valve is open.

  Embodiments of the present invention will be described below with reference to the drawings.

  A braking force control apparatus according to an embodiment of the present invention is shown in FIG. In FIG. 1, a braking force control device 1 includes a drive unit 2 that drives a vehicle, a torque transmission unit 3 that transmits torque generated by the drive unit 2 to wheels, a braking unit 4 that brakes the vehicle, and a drive unit. 2 and an ECU (Engine Control Unit) 5 that controls the torque transmission unit 3 and the braking unit 4.

  The drive unit 2 includes an engine 20, an intake pipe 21 for introducing an air-fuel mixture to the engine 20, a throttle valve 22 that adjusts the amount of air sent to the intake pipe 21 according to control by the ECU 5, and an opening of the throttle valve 22. A throttle position sensor 23 for detecting the degree and an engine speed sensor 24 for detecting the speed of the engine 20 are provided.

  The torque transmission unit 3 includes a transmission 30, a torque converter 31 that converts torque transmitted from the engine 20 to the transmission 30, and a vehicle speed sensor 32 that is provided on the output side of the transmission 30 and detects the current vehicle speed. ing.

  The torque converter 31 includes a pump 35 to which torque generated by the engine 20 is transmitted, a turbine 36 connected to the transmission 30, and a stator 37 interposed between the pump 35 and the turbine 36. Torque transmitted to the pump 35 is transmitted to the turbine 36 via a working fluid such as oil that satisfies the above.

  The brake unit 4 includes a brake booster 41 that boosts the pedaling force of the brake pedal 40 by the negative pressure generated in the intake pipe 21 as the engine 20 rotates, and the pedaling force boosted by the brake booster 41. A master cylinder 42 that generates the corresponding hydraulic pressure and a brake cylinder 43 that suppresses the rotation of the wheels by the hydraulic pressure generated by the master cylinder 42 are provided.

  The brake booster 41 uses the pressure difference between the negative pressure and the atmospheric pressure obtained by communicating with the inside of the intake pipe 21 via the pressure guiding pipe 50 to boost the pedaling force of the brake pedal 40.

  The ECU 5 has a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory) (not shown), and the CPU reads the program stored in the ROM into the RAM. The ECU 5 controls the drive unit 2, the torque transmission unit 3, and the braking unit 4 by executing the program read in the above.

  By causing the CPU to execute the program in this way, the ECU 5 according to the present invention can detect the open failure of the throttle valve 22 and the brake required for the negative pressure chamber 51 for the brake booster 41 to function. The required engine speed calculating means for calculating the required engine speed that is the speed of the engine 20 required to obtain the booster required negative pressure, and the engine speed detected by the engine speed sensor 24 is the required engine speed. The engine speed determining means for determining whether or not the engine speed is below the engine speed and the engine speed adjusting means for adjusting the engine speed so as to exceed the required engine speed.

  In addition to the program to be executed by the CPU, the ROM constituting the ECU 5 includes an air load factor which is a characteristic of the brake booster necessary negative pressure and the air load factor KL of the engine 20 with respect to the negative pressure in the intake pipe 21. The characteristic, the air flow rate characteristic which is the characteristic of the air flow rate Q supplied to the engine 20 with respect to the opening degree of the throttle valve 22, the speed ratio of the pump 35 and the turbine 36 of the torque converter 31, and the engine specifications are stored. Yes. Here, the engine specifications include, for example, the displacement of the engine 20. Further, in this ROM, a turbine rotational speed characteristic that is a characteristic of the rotational speed of the turbine 36 with respect to the vehicle speed is stored for each gear of the transmission 30.

  Thus, in the present invention, the ECU 5 according to the present invention, the brake booster required negative pressure storage means for storing the brake booster required negative pressure, and the characteristic storage means for storing the air load factor characteristic, the air flow characteristic and the engine 20 exhaust amount. The turbine rotational speed characteristic storage means for storing the turbine rotational speed characteristic for each gear of the transmission 30 is configured.

  The operation of the braking force control apparatus 1 configured as described above will be described with reference to FIGS. 2 and 3 are flowcharts showing a braking force control operation by the ECU 5. FIG.

  First, the ECU 5 detects whether or not the throttle valve 22 has an open failure (S1). Here, the open failure of the throttle valve 22 means, for example, a state in which the throttle valve 22 is fixed at a certain opening degree without depending on control by the ECU 5. The ECU 5 detects an open failure of the throttle valve 22 by comparing the opening required for the throttle valve 22 with the opening obtained from the throttle position sensor 23.

  When it is detected that the throttle valve 22 has an open failure, the ECU 5 calculates a necessary engine speed (S2). Here, in FIG. 3, the ECU 5 first specifies the air load factor KL corresponding to the negative pressure in the intake pipe 21 required for obtaining the brake booster necessary negative pressure in the air load factor characteristic (S21). It should be noted that the negative pressure in the intake pipe 21 required for obtaining the brake booster necessary negative pressure can be calculated by multiplying the brake booster necessary negative pressure by a coefficient. This coefficient is determined by the pressure loss generated from the intake pipe 21 to the negative pressure chamber 51 of the brake booster 41, but is set to 1 in the present embodiment.

  Further, the ECU 5 specifies an air flow rate Q corresponding to the opening degree of the throttle valve 22 detected by the throttle position sensor 23 in the air flow characteristic (S22).

  Here, the ECU 5 calculates the required engine speed based on the specified air flow rate Q and air load factor KL and the exhaust amount of the engine 20 (S23).

  Here, the calculation of the required engine speed will be described in detail with reference to FIG.

  The air flow rate characteristic is a characteristic of the air flow rate Q supplied to the engine 20 with respect to the opening degree of the throttle valve 22, and the air flow rate Q increases as the opening degree of the throttle valve 22 increases. On the other hand, the air load factor characteristic is a characteristic of the air load factor KL of the engine 20 with respect to the brake booster necessary negative pressure, and the air load factor KL becomes higher as the brake booster necessary negative pressure becomes closer to the atmospheric pressure.

  That is, the air flow rate Q represents the amount of air supplied to the engine 20 per unit time based on the opening degree of the throttle valve 22 obtained from the throttle position sensor 23. On the other hand, the air load factor KL represents the ratio of the amount of air supplied to the engine 20 per unit time with respect to the stroke volume EQ of the engine 20 per unit time for obtaining the required brake booster negative pressure, that is, the ratio of the air flow rate Q. ing.

  Since the stroke volume EQ of the engine 20 per unit time is obtained from the product of the rotational speed of the engine 20 and the displacement, the air load factor KL is (air flow rate Q / (engine rotational speed / 2 × displacement)). Can be calculated.

  Therefore, the ECU 5 determines ((air flow rate Q / air load factor KL) × 2 / displacement amount) × unit conversion value as a required engine speed for obtaining the air load factor KL necessary for the function of the brake booster 41. Is calculated. The unit conversion value refers to a constant for mutually converting the units of the air flow rate Q, the air load factor KL, and the exhaust amount.

  In FIG. 2, the ECU 5 next determines whether or not the rotational speed of the engine 20 detected by the engine rotational speed sensor 24 is lower than the required engine rotational speed (S3). If it is determined that the rotational speed of the engine 20 detected by the engine rotational speed sensor 24 is lower than the required engine rotational speed, the ECU 5 causes the gear of the transmission 30 that the rotational speed of the engine 20 is equal to or higher than the required engine rotational speed. Is selected (S4).

  Specifically, the ECU 5 determines that the rotational speed of the turbine 36 corresponding to the vehicle speed detected by the vehicle speed sensor 32 in the turbine rotational speed characteristics corresponds to the required engine rotational speed in the speed ratio of the torque converter 31. The gear of the transmission 30 as described above is selected.

  Here, the ECU 5 selects the lowest gear (for example, first gear) when there is no gear of the transmission 30 in which the rotation speed of the turbine 36 is equal to or higher than the rotation speed of the turbine 36 corresponding to the required engine rotation speed. You may do it.

  Further, the ECU 5 selects the highest gear among the gears of the transmission 30 in which the rotation speed of the turbine 36 is equal to or higher than the rotation speed of the turbine 36 corresponding to the required engine rotation speed so as to prevent excessive rotation of the engine 20. Is desirable.

  For example, in the turbine rotational speed characteristics as shown in FIG. 5, when the vehicle speed detected by the vehicle speed sensor 32 is υ, the ECU 5 sets the turbine 36 corresponding to the required engine rotational speed in the speed ratio of the torque converter 31. The highest 2nd gear is selected from the 1st and 2nd gears that are equal to or higher than the number of revolutions (indicated by a one-dot chain line in FIG. 5).

  In FIG. 2, next, the ECU 5 sets the gear of the transmission 30 to the selected gear (S5).

  Such a braking force control apparatus 1 according to an embodiment of the present invention adjusts the rotation speed of the engine 20 so as to obtain a negative pressure necessary for the function of the brake booster 41, and therefore, when the throttle valve 22 is in an open failure state. The negative pressure required to make the brake booster 41 function can be guaranteed.

Functional block diagram of a braking force control device in one embodiment of the present invention The flowchart for demonstrating operation | movement of the braking force control apparatus in one embodiment of this invention. Flowchart following FIG. The conceptual diagram for demonstrating calculation operation | movement of the required engine speed by the braking force control apparatus in one embodiment of this invention The graph which shows an example of the turbine speed characteristic used for the braking force control apparatus in one embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Braking force control apparatus 2 Drive part 3 Torque transmission part 4 Braking part 5 ECU
20 Engine 21 Intake pipe 22 Throttle valve 23 Throttle position sensor 24 Engine speed sensor 30 Transmission 31 Torque converter 32 Vehicle speed sensor 35 Pump 36 Turbine 37 Stator 40 Brake pedal 41 Brake booster 42 Master cylinder 43 Brake cylinder 50 Impulse pipe

Claims (8)

In a braking force control device for controlling a braking force of a vehicle provided with a brake booster that functions by a negative pressure generated in an intake pipe as the engine rotates,
Brake booster required negative pressure storage means for storing a brake booster required negative pressure necessary for causing the brake booster to function;
An open failure detection means for detecting an open failure of the throttle valve;
When the open failure is detected by the open failure detection means, required engine speed calculation means for calculating a required engine speed that is the engine speed required to obtain the brake booster required negative pressure;
A braking force control device comprising engine speed adjusting means for adjusting the engine speed so as to exceed the required engine speed. An air load factor characteristic that is a characteristic of the air load factor of the engine with respect to the negative pressure in the intake pipe, an air flow rate characteristic that is a characteristic of an air flow rate supplied to the engine with respect to an opening of the throttle valve, Characteristic storage means for storing the displacement,
The required engine speed calculating means has an air load factor corresponding to the negative pressure in the intake pipe required for obtaining the required negative pressure of the brake booster on the air load factor characteristic, and the air flow rate to the opening of the throttle valve. The braking force control device according to claim 1, wherein the required engine speed is calculated based on an air flow rate corresponding to a flow rate characteristic and the exhaust amount. A rotational speed determination means for determining whether or not the rotational speed of the engine detected by an engine rotational speed sensor provided in the engine is lower than the required engine rotational speed;
When the engine speed adjusting means determines that the engine speed detected by the engine speed sensor is lower than the required engine speed, the engine speed is set to the required engine speed. The braking force control apparatus according to claim 1 or 2, wherein a gear of the transmission that is equal to or higher than an engine speed is set. Turbine rotational speed characteristics for storing, for each gear of the transmission, turbine rotational speed characteristics that are characteristics of the rotational speed of a turbine provided on the transmission side of a torque converter that converts torque transmitted from the engine to the transmission. A storage means,
The engine rotation speed adjusting means is a gear for setting the gear in which the rotation speed of the turbine corresponding to the current vehicle speed in the turbine rotation speed characteristics is equal to or higher than the rotation speed of the turbine corresponding to the required engine rotation speed. The braking force control device according to claim 3, wherein the braking force control device is selected. In a braking force control method for controlling a braking force of a vehicle provided with a brake booster that functions by a negative pressure generated in an intake pipe as the engine rotates,
Brake booster necessary negative pressure necessary for functioning the brake booster is stored in a storage medium,
An open failure detection means for detecting an open failure of the throttle valve;
Necessary engine speed calculation means needs to calculate a required engine speed that is the engine speed required to obtain the brake booster required negative pressure when the open failure is detected in the open failure detection step. An engine speed calculation step;
A braking force control method, characterized in that the engine speed adjusting means includes an engine speed adjusting step for adjusting the engine speed so as to exceed the required engine speed. An air load factor characteristic that is a characteristic of the air load factor of the engine with respect to the negative pressure in the intake pipe, an air flow rate characteristic that is a characteristic of an air flow rate supplied to the engine with respect to an opening of the throttle valve, Store the displacement in a storage medium,
In the required engine speed calculating step, the required engine speed calculating means has an air load factor corresponding to the negative pressure in the intake pipe required for obtaining the brake booster required negative pressure in the air load factor characteristic; 6. The braking force control method according to claim 5, wherein the required engine speed is calculated based on an air flow rate corresponding to an opening degree of the throttle valve in the air flow characteristic and the exhaust amount. . A rotational speed determination means for determining whether or not the rotational speed of the engine detected by an engine rotational speed sensor provided in the engine is below the required engine rotational speed;
In the engine rotation speed adjustment step, when it is determined in the rotation speed determination step that the rotation speed detected by the engine rotation speed sensor is lower than the required engine rotation speed, the engine rotation speed adjustment means 7. The braking force control method according to claim 5, wherein a transmission gear is set so that the engine speed is equal to or higher than the required engine speed. A turbine speed characteristic, which is a characteristic of a rotational speed of a turbine provided on the transmission side of a torque converter for converting torque transmitted from the engine to the transmission, with respect to a vehicle speed is stored in a storage medium for each gear of the transmission. Every
In the engine rotation speed adjustment step, the engine rotation speed adjustment means causes the rotation speed of the turbine corresponding to the current vehicle speed on the turbine rotation speed characteristics to be equal to or higher than the rotation speed of the turbine corresponding to the required engine rotation speed. The braking force control method according to claim 7, wherein the gear is selected as a gear to be set.

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