JP2014194196A - Vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive vehicle control device which can perform idle stop control without installing a liquid-pressure sensor.SOLUTION: A vehicle control device 2 which estimates brake pressure used in the control of an idle stop vehicle 1 comprises: a negative pressure sensor 4a which sequentially detects negative pressure generated by the drive of an engine 5; a brake control ECU 14 which estimates the brake pressure on the basis of the negative pressure detected by the negative pressure sensor 4a; and storage means 20 which stores brake pressure in the case that a brake operation is not performed as initial brake pressure, and stores the estimated brake pressure. The brake control ECU 14 firstly estimates brake pressure on the basis of the initial brake pressure which is stored by the storage means 20 and the detected negative pressure, and after that, newly estimates brake pressure on the basis of the past estimated pressure and an amount of change of the negative pressure after the estimation of the past estimated brake pressure.

Description

  The present invention relates to a vehicle control device for an idle stop vehicle.

  Conventionally, an idle stop vehicle for the purpose of improving the fuel consumption of a vehicle is known. This idle stop vehicle automatically stops the engine (idle stop) after the vehicle speed is reduced to 0 km / h by deceleration on condition that a predetermined engine automatic stop condition such as a brake pedal being depressed is satisfied, The engine is restarted when a predetermined engine restart condition is established during idle stop.

  By the way, in order to further improve fuel efficiency in recent years, it has been proposed to automatically stop the engine when a predetermined engine automatic stop condition is satisfied before the vehicle speed reaches 0 km / h due to deceleration (during traveling) (patent). Reference 1). The idle stop vehicle detects a brake pressure (master cylinder pressure) applied to the brake device by a hydraulic pressure sensor, detects a vehicle speed of the host vehicle by a wheel speed sensor, and the vehicle speed is equal to or lower than a predetermined vehicle speed, and The engine is automatically stopped on condition that these conditions are satisfied, assuming that the brake pressure is equal to or higher than a predetermined value. In addition, the engine is configured to restart when the brake pedal is switched from the accelerator pedal to the accelerator pedal during idle stop and the driver indicates the intention to restart (establishment of the engine restart condition).

JP 2012-76520 A (see paragraphs 0021 to 0023, 0027, etc.)

  In this type of driving support device, a hydraulic pressure sensor that detects the brake hydraulic pressure applied to the brake device is required to determine whether the engine automatic stop condition and the engine restart condition are satisfied (idle stop control). Therefore, there is a demand for making the hydraulic pressure sensor unnecessary.

  The present invention has been made in view of the above problems, and an object thereof is to provide an inexpensive vehicle control device that can realize idle stop control without providing a hydraulic pressure sensor.

  In order to achieve the above-described object, the vehicle control device according to the present invention is a vehicle control device that estimates a brake pressure used for vehicle control, and detects negative pressure generated by driving an engine sequentially. A pressure detecting means; an estimating means for estimating the brake pressure as an estimated brake pressure based on the negative pressure detected by the negative pressure detecting means; and a brake pressure when the brake is not operated is stored as an initial brake pressure. Storage means for storing the estimated brake pressure, and the estimation means estimates the estimated brake pressure based on the initial brake pressure and the detected negative pressure stored by the storage means for the first time. Then, a new estimated brake pressure is estimated based on the past estimated brake pressure and the amount of change in the negative pressure from the estimated previous estimated brake pressure. Is characterized (claim 1).

  According to the first aspect of the present invention, the estimating means estimates the brake pressure (master cylinder pressure) applied to the brake device as the estimated brake pressure based on the negative pressure detected by the negative pressure detecting means. Since a hydraulic pressure sensor for detecting the brake pressure applied to the brake device is not required unlike a conventional idle stop vehicle, an inexpensive vehicle control device can be provided.

  Further, in estimating the brake pressure by the estimation means, in order to estimate a new brake pressure based on the past estimated brake pressure and the amount of change in the negative pressure from the estimated time of the past estimated brake pressure, for example, The brake pressure applied to the brake device can be accurately estimated as compared with the case where the brake pressure is estimated using a map.

It is a block diagram of the control device for vehicles concerning one embodiment of the present invention. It is operation | movement explanatory drawing of the control apparatus for vehicles of FIG. It is a figure for demonstrating the estimation method of brake pressure.

  A vehicle control device 2 according to an embodiment of the present invention will be described with reference to FIGS. 1 is a block diagram of a vehicle control device 2 according to an embodiment of the present invention provided in an idle stop vehicle 1, FIG. 2 is an operation explanatory view of the vehicle control device 2, and FIG. The relationship between the operation amount of the brake pedal and time, (b) shows the relationship between brake booster negative pressure (booster negative pressure) and time, and (c) shows the relationship between estimated brake pressure and time. FIG. 3 is a diagram for explaining a method of estimating the brake pressure of the driving assistance device 2 according to this embodiment.

  FIG. 1 shows a vehicular control device provided in an idle stop vehicle 1 that automatically stops an engine when a predetermined engine automatic stop condition is satisfied and performs an idle stop, and restarts the engine when a predetermined engine restart condition is satisfied. 2, 3 is a brake pedal, 4 is a brake booster to which a negative pressure generated by driving the engine 5 is supplied, and 4 a is a negative pressure (booster negative pressure) of the brake booster 4 for a predetermined period (for example, 0. 0). 5 ms), a negative pressure sensor (corresponding to the negative pressure detection means of the present invention), 6 is a master cylinder to which the pedal force of the brake pedal 3 is applied via the brake booster 4, 7 is a pipe connected to the master cylinder 6, A brake actuator 8 includes a solenoid valve group 9.

  The solenoid valve group 9 includes a plurality of solenoid valves including brake hydraulic pressure control valves 9a and 9b. The brake fluid pressure control valves 9a and 9b are provided for each of, for example, two systems branched from the pipe 7, and are also used for idle stop and brake control of the running ESC and TCS. 10FL and 10FR are the left and right front wheel wheel cylinders of the idle stop vehicle 1, and 10RL and 10RR are the left and right rear wheel wheel cylinders of the idle stop vehicle 1, for example, one system extending from the brake fluid pressure control valve 9a. The left front wheel wheel cylinder 10FL and the right rear wheel wheel cylinder 10RR are connected to the pipes 11FL, 11RR, and the other system pipe 11FR, 11RL extending from the brake fluid pressure control valve 9b is connected to the right front wheel wheel cylinder 10FR, left A rear wheel cylinder 10RL is connected.

  The idle stop vehicle 1 is provided with an in-vehicle network 12 such as a CAN. The in-vehicle network 12 includes an idle stop control ECU 13, a brake control ECU 14 in the brake actuator 8, an engine control ECU 15, a transmission control ECU 16, and the like. Are connected to each other, and the ECUs 13 to 16 exchange information via the in-vehicle network 12.

  Each of the ECUs 13 to 16 is formed of a microcomputer, the engine control ECU 15 controls the throttle opening degree of the engine 5, and the transmission control ECU 16 is a belt type CVT connected to the engine 5 via a torque converter (not shown). (Not shown). The details of the idle stop control ECU 13 and the brake control ECU 14 (corresponding to the estimation means of the present invention) will be described later.

  Next, the idle stop control ECU 13 and the brake control ECU 14 will be described.

  The idle stop control ECU 13 collects information such as a master cylinder pressure (estimated brake pressure) and a vehicle speed estimated by a brake control ECU 14 to be described later based on communication via the in-vehicle network 12 while the idle stop vehicle 1 is traveling, Idle stop control including automatic stop control and restart control of the engine 5 is executed.

  Specifically, a predetermined engine automatic stop condition (for example, a stop lamp is lit and the vehicle speed is set to a predetermined vehicle speed, for example, the accelerator pedal (not shown) is switched to the brake pedal 3 and the vehicle speed decreases to a predetermined vehicle speed or less. When the estimated brake pressure is equal to or greater than a predetermined value, the idle stop control ECU 13 sends a brake fluid pressure holding request to the brake control ECU 14 via the in-vehicle network 12 and at the same time, the engine of the idle stop is sent to the engine control ECU 15. Send a stop request signal. Based on this engine stop request signal, the engine control ECU 15 automatically stops the engine 5.

  A stop lamp (not shown) is turned on when the brake pedal 3 is depressed, and the lighting is detected by the brake switch 18. The vehicle speed is detected by a wheel speed sensor 19 for four wheels. At this time, the information on the on / off state of the brake switch 18 and the vehicle speed detected by the wheel speed sensor 19 is taken into the brake control ECU 14 and sent from the brake control ECU 14 to the idle stop control ECU 13 via the in-vehicle network 12. Information about the brake pressure estimated by the brake control ECU 14 is also sent to the idle stop control ECU 13 via the in-vehicle network 12.

  Furthermore, when the driver continues to step on the brake pedal 3, the braking force of the master cylinder pressure is applied to each wheel cylinder 10FL to 10RR, and the idle stop vehicle 1 is decelerated and traveling stops.

  Further, the idle stop control ECU 13 receives an engine restart request signal when an engine restart condition is satisfied, for example, when the driver switches from the brake pedal 3 to the accelerator pedal while the engine 5 is automatically stopped by the automatic stop control. Is transmitted to the engine control ECU 15 via the in-vehicle network 12. Then, the engine control ECU 15 that has received this engine restart request signal restarts the engine 5. At this time, for example, the engine restart condition is a case where the brake pressure (master cylinder pressure) is equal to or lower than a predetermined value. Based on.

  The brake control ECU 14 controls the hill hold in order to prevent the idle stop vehicle 1 from sliding down during the automatic stop control, for example, when the automatic stop control of the engine 5 is executed while the idle stop vehicle 1 is traveling uphill. Execute control. Specifically, the brake control ECU 14 that has received the brake fluid pressure holding request signal gives a solenoid command current to the brake fluid pressure control valves 9a and 9b when the engine 5 is decelerated to a predetermined vehicle speed or less after the engine 5 is automatically stopped. Energization of the hydraulic pressure holding solenoids of the brake hydraulic pressure control valves 9a and 9b is started. At this time, the brake control ECU 14 gradually increases the energization amount of the hydraulic pressure holding solenoids of the brake hydraulic pressure control valves 9a and 9b by increasing the solenoid instruction current in accordance with the decrease in the vehicle speed from the predetermined vehicle speed or less. The time lag until the brake fluid pressure control valves 9a and 9b actually operate is gradually shortened by the solenoid instruction current.

  By doing so, the brake is applied at a strength corresponding to the vehicle speed of the idle stop vehicle 1 during the automatic stop of the engine 5, so that the idle stop vehicle 1 can be prevented from sliding down.

  Further, the brake control ECU 14 determines the brake pressure (master) for determining whether or not the engine stop request signal is transmitted to the engine control ECU 15 by the idle stop control ECU 13 and whether or not the engine restart request signal is transmitted. (Cylinder pressure) is estimated every predetermined period (for example, 0.5 ms) (estimated brake pressure), and the information is sequentially transmitted to the idle stop control ECU 13 via the in-vehicle network 12. At this time, the brake control ECU 14 estimates the brake pressure based on the negative pressure (booster negative pressure) of the brake booster 4 detected by the negative pressure sensor 4a.

  Specifically, the brake control ECU 14 includes a storage unit 20 composed of a ROM and a RAM, and the ROM stores a brake pressure when the brake operation is not performed as an initial brake pressure Pmc0. In the first time, the brake pressure (initial estimated brake pressure Pmc1) is estimated based on the initial brake pressure Pmc0 and the negative pressure (booster negative pressure) detected by the negative pressure sensor 4a. A new brake pressure is estimated based on the pressure and the amount of change in the booster negative pressure from the estimated estimated brake pressure in the past. In this embodiment, the initial brake pressure Pmc0, which is the brake pressure when the brake operation is not performed, is stored as 0 in the storage unit 20 of the brake control ECU 14.

  Next, the brake pressure estimation method will be described more specifically with reference to FIGS. By the way, the brake booster 4 includes a constant pressure chamber that accumulates engine negative pressure generated by driving the engine 5, and a variable pressure chamber that accumulates air higher than the engine negative pressure, and the negative pressure sensor 4a. Detects the pressure in the constant pressure chamber as a booster negative pressure (negative pressure). Here, for example, when the brake operation is not performed (time t0: initial brake pressure Pmc0), the pressure (negative pressure) in the constant pressure chamber is P0, volume V1, the pressure in the variable pressure chamber is P0, and volume V2. A method for estimating the brake pressure (master cylinder pressure) will be described. When the brake operation is not performed, the brake booster 4 is in an inoperative state, and the valve 21a between the constant pressure chamber and the variable pressure chamber is in an open state (see FIG. 3A).

  As shown in FIG. 3B, when the brake pedal 3 is operated by the driver, the brake booster 4 is activated, the valve 21a is closed, and the air introduction valve 21b (air valve) of the variable pressure chamber is opened. Thus, the master cylinder pressure is increased. At this time (time t1), assuming that the booster negative pressure in the constant pressure chamber is P1, the volume V1-ΔV, the pressure in the variable pressure chamber is P2, and the volume is V2 + ΔV, the relationship of the following equation (1) is obtained according to Boyle's law. To establish. ΔV is the amount of change in the volume of the constant pressure chamber from time t0 to time t1, and the volume V1 of the constant pressure chamber and the volume V2 of the variable pressure chamber when the brake booster 4 is not in operation are known values.

  Therefore, the amount of change ΔPα of the booster negative pressure from the time when the brake operation is not performed (time t0) to the time when the estimated brake pressure Pmc1 is estimated for the first time (time t1) is expressed as ΔPα = P1−P0 = P0 · ΔV / (V1−ΔV), and the brake control ECU 14 calculates the change amount ΔV of the volume of the constant pressure chamber based on the change amount ΔPα of the booster negative pressure detected by the negative pressure sensor 4a.

At this time (from time t0 to time t1), the relationship between the change amount ΔPmca of the master cylinder pressure and the change amount ΔV of the volume is that the hydraulic rigidity of the brake system is K [MPa / cc] and the area of the booster diaphragm is Ab ^{[m 2],} and the area of the master cylinder 6 and Amc ^{[m 2],} the number 2 in the following (2) the relationship equation is established. At this time, K, Ab, and Amc are constants.

  Therefore, the brake control ECU 14 calculates the change amount ΔPmca of the master cylinder pressure from the time t0 to the time t1 based on the equation (2) of Formula 2 to thereby obtain the first (time t1) brake pressure Pmc1 (= Pmc0 + ΔPmca). Is estimated. At this time, the initial brake pressure Pmc0 is stored in the storage means 20 (for example, RAM) of the brake control ECU 14, and the initial estimated brake pressure Pmc1 is estimated based on the initial brake pressure Pmc0 and the calculated ΔPmca.

  Subsequently, at the next estimation (second time) (for example, time t2), the second estimation is performed in the same manner based on the relational expression of Equation (1) in Equation 1 and Equation (2) in Equation 2 above. The brake pressure Pmc2 (= Pmc1 + ΔPmcb) is estimated. At this time, ΔV is the amount of change in the volume of the constant pressure chamber from time t1 to time t2, and ΔPmcb (corresponding to ΔPmca in equation (2) in equation 2) is the brake pressure (estimated brake pressure) from time t1 to time t2. ) And ΔPβ (corresponding to ΔPα) as the amount of change (= P3-P1) of the negative pressure (booster negative pressure) in the constant pressure chamber from time t1 to time t2, the second estimated brake pressure Pmc2 is estimated. . The initial estimated brake pressure Pmc1 is stored in the storage means 20 (for example, RAM) of the brake control ECU 14, and the second estimated time is based on the stored initial estimated brake pressure Pmc1 and the calculated ΔPmcb. The brake pressure Pmc2 is estimated. The brake pressure (estimated brake pressure) is similarly estimated after the third time.

  Note that the estimation of the brake pressure is not limited to the case of performing the estimation based on the previous estimated brake pressure and the amount of change in the booster negative pressure from the previous estimation. The estimation may be based on the brake pressure. In this case, the amount of change from the booster negative pressure P3 at the time of the second estimation (time t2) is detected, the amount of change ΔV in the constant pressure chamber from the second time is calculated, and the amount of change ΔV is described above. The fourth estimated brake pressure may be estimated based on Equation (2) in Equation 2.

  Therefore, according to the above-described embodiment, the brake pressure (master cylinder pressure) used for determining whether the idle stop control ECU 13 transmits the engine automatic stop request signal or the engine restart request signal to the engine control ECU 15 is determined. The brake control ECU 14 estimates the amount of change in the booster negative pressure, and sends the information to the idle stop control ECU 13 so that the brake pressure (master cylinder pressure) applied to the brake device as in a conventional idle stop vehicle. ) Is not required, so that an inexpensive vehicle control device 2 can be provided.

  In addition, when the brake control ECU 14 estimates the brake pressure (estimated brake pressures Pmc1, Pmc2), the past estimated brake pressure and the amount of change in the booster negative pressure (negative pressure) from the estimation of the past estimated brake pressure In order to estimate a new brake pressure (estimated brake pressure) based on, for example, it is possible to estimate the brake pressure applied to the brake device more accurately than when the brake pressure is estimated using a map it can.

  The present invention is not limited to the above-described embodiments, and various modifications other than those described above can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the case where the brake pressures Pmc1 and Pmc2 (estimated brake pressure) estimated by the brake control ECU 14 are used for the control of the idle stop control ECU 13 has been described, but the estimated brake pressures Pmc1 and Pmc2 are used in other cases. The brake pressure may be used for various types of control that require information.

  Further, the brake pressure (estimated brake pressure) may be estimated by the idle stop control ECU 13.

  In the above-described embodiment, the initial brake pressure Pmc0 and the estimated brake pressures Pmc1 and Pmc2 are stored in the storage unit 20 provided in the brake control ECU 14, but the storage unit 20 may be provided separately. Absent.

1 ... Idle stop car (vehicle)
2 ... Vehicle control device 4a ... Negative pressure sensor (negative pressure detecting means)
14 ... Brake control ECU (estimating means)
20 ... Storage means

Claims (1)

A vehicle control device that estimates a brake pressure used for vehicle control,
Negative pressure detecting means for sequentially detecting negative pressure generated by driving the engine;
Estimating means for estimating the brake pressure as an estimated brake pressure based on the negative pressure detected by the negative pressure detecting means;
Storing a brake pressure when the brake is not operated as an initial brake pressure, and storing means for storing the estimated brake pressure,
The estimation means estimates an estimated brake pressure based on the initial brake pressure stored in the storage means and the detected negative pressure for the first time, and then determines a past estimated brake pressure and the past estimated brake. A new estimated brake pressure is estimated based on the amount of change in negative pressure from the time of pressure estimation.

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