JP2006132451A - Idle stop control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an idle stop control system which can assure a brake liquid pressure required for a vehicle stop even when a signal from a brake liquid pressure sensor is transmitted in a delay to a brake control device. <P>SOLUTION: In the idle stop control system provided with a brake hydraulic sensor 242; an ABSCU 220 to perform hill-hold control; and an idle stop control part 210, the idle stop control part 210 to which the brake hydraulic sensor 242 is connected is made to transmit a correction brake hydraulic pressure, where brake hydraulic pressure information is corrected according to the communication delay of a CAN 250, to the ABSCU 220 through the CAN 250. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an idle stop control provided with a hill hold device that holds a vehicle braking force regardless of a driver's brake operation when the vehicle stops on a slope.

This type of technology includes an ABS actuator that has a hydraulic pressure holding valve that holds the brake hydraulic pressure of the wheel cylinder. When the engine is automatically started when the idle stop is released, the hydraulic pressure is maintained until the automatic start of the engine is completed. A valve that closes a valve and maintains a brake fluid pressure is disclosed (for example, see Patent Document 1).
JP 2003-260960 A

  However, when the above technique is used in a configuration in which the signal of the brake fluid pressure sensor is transmitted to the brake control device by communication means such as CAN, the brake fluid pressure detection in the brake control device may be delayed due to communication delay. Therefore, the hill hold control command by the brake control device holds the brake hydraulic pressure lower than the brake hydraulic pressure at which the hill hold should be performed, and there is a problem that the vehicle may slip down on a slope. .

  The present invention has been made paying attention to the above problems, and the purpose of the present invention is to provide a brake necessary for stopping the vehicle even when the signal of the brake fluid pressure sensor is transmitted to the brake control device with a delay. An object of the present invention is to provide an idle stop control system that can ensure hydraulic pressure.

  In order to achieve the above object, in the present invention, a braking force detection device that detects actual braking force and outputs it as braking force information, a hill hold control device that holds braking force required when the vehicle stops on a slope, In an idle stop control system comprising an idle stop control device that automatically stops the engine when the vehicle is stopped and automatically starts when the brake force information reaches a predetermined value or less, the brake force detection device is connected to the idle stop control device. The idle stop control device is connected to the hill hold control device by a communication circuit, and includes a correction unit that corrects brake force information in accordance with communication delay of the communication circuit.

  In the idle stop control system of the present invention, the brake fluid pressure required for stopping the vehicle can be ensured even when the signal from the brake fluid pressure sensor is transmitted to the brake control device with a delay.

  The best mode for carrying out the idle stop control system of the present invention will be described below with reference to the drawings.

  First, the configuration of the present embodiment will be described.

  FIG. 1 is an overall system diagram showing a configuration of a drive system, a control system, and a brake system of a vehicle provided with the idle stop control system of the present embodiment.

  As a vehicle drive system, an engine 100, an oil pump 110 driven by the engine to generate hydraulic pressure, a torque converter 120 that increases the output torque of the engine 100, and a continuously variable transmission / reception of power from the engine 100 and a shift. A transmission 130.

  The engine 100 includes a gasoline engine, a diesel engine, or the like. The power generation device may be a hybrid using not only an engine but also a motor. The engine 100 is connected to a starter motor 101 that starts the engine 100, an air conditioner 102 that is driven by the power of the engine 100, and a water pump 103.

  The torque converter 120 includes a pump impeller connected to the engine output shaft, a turbine runner connected to the transmission input shaft, a stator for adjusting the flow of internal hydraulic oil, and a lock for directly transmitting power during high-speed traveling. And an up clutch.

  The continuously variable transmission 130 includes a starting clutch and a continuously variable transmission (not shown). The starting clutch is configured to be switchable between an engaged state in which power can be transmitted between input and output and a released state in which power cannot be transmitted to the output side portion. The continuously variable transmission 130 performs a continuously variable transmission by controlling the groove width of each pulley by winding a belt between the pulleys of each pulley between the primary pulley on the input side and the secondary pulley on the output side. .

  Next, the control system of this embodiment will be described with reference to FIG.

  As a control system of the present embodiment, an engine control module (Engine Control Module: hereinafter referred to as ECM) 200 for controlling the engine 100, an idle stop control unit 210 incorporated in the ECM 200, and a brake system described later are controlled. An anti-lock brake system control unit (Anti-lock Brake System Control Unit: hereinafter referred to as ABSCU) 220 and a continuously variable transmission control unit (hereinafter referred to as CVTCU) that controls the continuously variable transmission 130 (Notation) 230. The ECM 200 and the ABSCU 220 are connected by a control area network (hereinafter referred to as CAN) 250, and the ECM 200 and the CVTCU 230 are connected by a CAN 251 so that bidirectional serial communication is possible. The CAN 250 corresponds to the communication line of the present invention.

  The ECM 200 detects an inclination sensor 241 that detects the inclination of the vehicle, a brake hydraulic pressure sensor 242 that detects a brake hydraulic pressure, a negative pressure sensor 243 that detects an intake-side negative pressure of the engine 100, and an open / closed state of the hood hood. A hood switch 244 or the like is connected. The ECM 200 controls the engine 100 and the starter motor 101 based on information from each sensor. The brake fluid pressure sensor 242 detects a brake fluid pressure in a brake fluid pressure circuit 370, which will be described later, and corresponds to a brake force detection device of the present invention. Instead of detecting the detected brake fluid pressure directly, it may be detected indirectly from the stroke of the piston in the master cylinder, or a value that can be substituted for detecting the magnitude of other brake fluid pressure may be used.

  The idle stop control unit 210 performs idle stop control based on brake fluid pressure information, engine expiratory negative pressure information, hood open / close information, and the like. The idle stop control unit 210 corresponds to the idle stop control device of the present invention.

  ABSCU 220 is connected to a wheel speed sensor 245 that detects a wheel speed. Based on brake fluid pressure information from ECM 200, idle stop control state information, hill hold release request information, and the like, and wheel speed information from wheel speed sensor 245, control signals are transmitted to holding valve 340 and pressure reducing valve 350, which will be described later. . The ABSCU 220 corresponds to the hill hold control device of the present invention.

  CVTCU 230 controls continuously variable transmission 130 based on an accelerator opening signal, a select lever signal, and the like from an accelerator opening sensor and a select lever sensor (not shown).

  Next, the brake system of this embodiment will be described with reference to FIG.

  The brake pedal 310 operated by the driver is connected to a negative pressure booster 320 that assists the driver's pedaling force and a master cylinder 330 that generates a brake fluid pressure corresponding to the assisted pedaling force.

  The ABS unit 300 is connected to the master cylinder 330. The ABS unit 300 includes a supply circuit 370 that supplies hydraulic pressure generated in the master cylinder 330 to the wheel cylinder 360, and a discharge circuit 380 that is connected to a reservoir tank 390 that discharges brake fluid acting on the wheel cylinder 360. . The supply circuit 370 is provided with a normally open type holding valve 340, and the discharge circuit 380 is provided with a normally closed type pressure reducing valve 350.

  Next, the operation will be described.

[Idle stop control]
The idle stop control unit 210 stops the engine 100 when an idle stop permission condition described later is satisfied, and restarts the engine 100 when an idle stop prohibition request condition is satisfied.

<Idle stop permission conditions>
-Select lever travel range (D range)
・ Vehicle speed = 0
・ All doors are closed. ・ Engine is running. ・ Brake fluid pressure is more than the specified value. ・ Bonnet hood is closed. If all the following conditions are met, the engine 100 is turned off. Stop.

-The amount of charge of the battery 160 is a predetermined value or more (to ensure the driving force of the starter motor 101 at the time of restart).
・ Brake booster negative pressure is more than the specified value (to ensure master cylinder pressure)
-Engine water temperature is above a specified value (to ensure smooth restart)
・ The oil temperature in the continuously variable transmission is above the specified value (to ensure smooth start control).
・ The oil pressure in the continuously variable transmission is greater than the specified value (to ensure the speed change response of the continuously variable transmission).
Although the idle stop permission is instructed based on the above conditions, the idle stop permission may be instructed based on other conditions.

<Idle stop release condition>
-Select lever is in travel position (D range)
・ Vehicle speed = 0
・ All doors are closed ・ Idle stop is in progress ・ Bonnet hood is closed Assuming that all the above conditions are satisfied, engine 100 is restarted when any one of the following conditions is satisfied.

・ Accelerator ON (because there is intention to start)
・ The brake fluid pressure is below the specified value (because there is intention to start or creep)
・ Lower battery charge (because it becomes difficult to secure the driving power of the starter motor at restart)
-Engine water temperature drop (because it is difficult to control smooth start)
・ Low oil temperature in continuously variable transmission (because it is difficult to ensure smooth start control)
・ Lower hydraulic pressure in the continuously variable transmission (because it is difficult to secure the speed response of the continuously variable transmission mechanism)
Although it is instructed to prohibit idling stop based on the above conditions, it may be instructed to permit idling stop based on other conditions.

  Next, the operation of the brake system will be described.

[Normal braking]
During normal braking operation, the holding valve 340 is opened and the pressure reducing valve 350 is closed. However, when the driver's pedaling force is strong and the wheel is locked, the holding valve 340 is closed and the pressure reducing valve 350 is opened. By doing so, ABS control is performed to release the hydraulic pressure in the wheel cylinder 360 to the reservoir tank 390. The brake fluid stored in the reservoir tank 390 is returned to the master cylinder 330 by a return circuit (not shown) to ensure a hydraulic pressure balance.

[Hill hold control]
When the engine 100 is stopped by the idle stop control, the engine 100 starts when the above-described idle stop cancellation condition is satisfied. However, the creep torque is not sufficiently generated until the engine 100 is completely exploded. At this time, for example, if the driver releases the brake pedal 310 for starting while the vehicle is stopped on a slope, the vehicle may move backward.

  Then, after the idle stop control is released by the idle stop control unit 210, when the brake fluid pressure decreases to a predetermined value or less, the ABSCU 220 closes the holding valve 340 and seals the brake fluid acting on the wheel cylinder 360. . As a result, hill hold control is performed to ensure the braking force regardless of the driver's braking operation and prevent the vehicle from moving backward. Thereafter, when the complete explosion determination of the engine 100 is made and the vehicle can move forward, the pressure reducing valve 350 is opened, and the hydraulic pressure of the wheel cylinder 360 is discharged to the reservoir tank 390 to start.

  In this embodiment, the brake fluid pressure sensor 242 is connected to the ECM 200, and the brake fluid pressure information is sent to the ABSCU 220 by the CAN 250. With this configuration, the ABSCU 220 may receive information delayed from the actual brake fluid pressure due to a communication delay in the CAN 250.

  The above will be described in detail with reference to FIG. The solid line shown in FIG. 2 is the brake fluid pressure information directly received by the ECM 200 from the brake fluid pressure sensor 242, and is almost the actual brake fluid pressure. The brake fluid pressure information is transmitted to the ABSCU 220. A one-dot chain line is brake fluid pressure information received by the ABSCU 220 via the CAN 250. P1 represents the brake fluid pressure idle stop release condition, and P2 represents the brake fluid pressure hill hold control start condition. In the following description, the brake fluid pressure information received by the ECM 200 from the brake fluid pressure sensor 242 is referred to as actual fluid pressure, and the brake fluid pressure information received by the ABSCU 220 via the CAN 250 is referred to as delayed fluid pressure. The actual hydraulic pressure corresponds to the first braking force of the present invention, and the delayed hydraulic pressure corresponds to the second braking force of the present invention.

  The idle stop control unit 210 cancels the idle stop at time T1 when the actual hydraulic pressure decreases to P1.

  Further, at time T2 when the brake fluid pressure decreases and the actual fluid pressure decreases to P2, ABSCU 220 must start hill hold control, but it starts hill hold control from time T2 ′ when the lag hydraulic pressure becomes P2. End up. At time T2 ′, the actual hydraulic pressure has already dropped to P2 ′, and the brake hydraulic pressure during hill hold control cannot be secured above P2 ′. If this P2 'is lower than the brake fluid pressure at which the vehicle can be stopped on the slope, the vehicle will fall off.

  Therefore, in this embodiment, the idle stop control unit 210 monitors the communication delay of the brake fluid pressure information received by the ABSCU 220, calculates the corrected brake fluid pressure from the communication delay time and the change amount of the actual fluid pressure, and this corrected brake fluid. The pressure was transmitted to ABSCU220.

  Next, calculation of the corrected brake fluid pressure of this embodiment and hill hold control when using the corrected brake fluid pressure will be described with reference to FIG. The solid line shown in FIG. 3 is the actual hydraulic pressure, and the thick line is the corrected brake hydraulic pressure. The one-dot chain line is the delayed hydraulic pressure. P1 represents the brake fluid pressure idle stop release condition, and P2 represents the brake fluid pressure hill hold control start condition.

  The idle stop control unit 210 cancels the idle stop at time T1 when the actual hydraulic pressure decreases to P1.

  At this time, the idle stop control unit 210 calculates the corrected brake hydraulic pressure from the time delay between the actual hydraulic pressure and the delayed hydraulic pressure and the amount of change in the actual hydraulic pressure. This corrected brake fluid pressure is transmitted from the ECM 200 to the ABSCU 220 until the hill hold control is started.

  Here, a method of calculating the corrected brake fluid pressure will be described in detail with reference to FIG. FIG. 4 is an enlarged view of the vicinity of the intersection of the brake fluid pressure P1 and time T1 in FIG.

  The idle stop control unit 210 calculates a time delay d between the actual hydraulic pressure and the delayed hydraulic pressure when the actual hydraulic pressure reaches the idle stop cancellation condition P1. Further, the gradient g is calculated by estimating the actual fluid pressure variation after time T1 from the actual fluid pressure variation before time T1. A correction amount c is obtained from the product of the time delay d and the slope g, and the actual hydraulic pressure corrected by c is defined as a corrected brake hydraulic pressure.

  Not only the above-mentioned method of calculating the corrected brake fluid pressure, but also the corrected brake fluid pressure is calculated so that the delayed fluid pressure does not cause a time delay when the actual fluid pressure becomes the hill hold control start condition of the brake fluid pressure. It ’s fine.

  The calculation of the corrected brake hydraulic pressure in the idle stop control unit 220 corresponds to the correcting means of the present invention.

  Since the corrected brake hydraulic pressure is transmitted from the ECM 200 to the ABSCU 220, the lag hydraulic pressure also becomes P2 at the time T2, so that the hill hold control can be started without causing a time lag.

  After the engine 100 completes explosion at time T3, the idle stop control unit 210 transmits the actual hydraulic pressure to the ABSCU 220 without calculating the corrected brake hydraulic pressure.

  Next, the flow of control in the idle stop control unit 210 will be described based on the flowchart of FIG.

  In step S1, it is determined whether the ignition key is ON. If it is ON, the process proceeds to step S2, and if it is OFF, the idle stop control is terminated.

  In step S2, brake fluid pressure information is input from the brake fluid pressure sensor 243.

  In step S3, brake fluid pressure information is transmitted to ABSCU 220.

  In step S4, the brake fluid pressure information received by the ABSCU 220, that is, the delay fluid pressure described above is received.

  In step S5, the CAN 250 communication delay is calculated from the delay hydraulic pressure.

  In step S6, it is determined whether or not the above-described idle stop permission condition is satisfied, and if satisfied, the process proceeds to step S7 to perform idle stop. If the condition is not satisfied, the idle stop is canceled and the process proceeds to step S8.

  In step S8, it is determined whether the engine 100 has started, and if it has started, the process returns to step S1. If engine 100 has not been started, the corrected corrected brake fluid pressure is transmitted to ABSCU 220.

  Next, the effect of the idle stop control device of this embodiment will be described.

  (1) Even if a communication delay occurs in CAN 250, when the actual hydraulic pressure becomes P2 in the idle stop control unit 210, the corrected brake hydraulic pressure is transmitted so that the delayed hydraulic pressure also becomes P2. Hill hold control can be started when is P2. Accordingly, the brake fluid pressure necessary for stopping the vehicle on the slope can be maintained, so that the vehicle can be prevented from slipping down.

  (2) Since the idle stop control unit 210 calculates the corrected brake fluid pressure based on the communication delay time of the CAN 250 and the actual fluid pressure change amount, the communication delay time and the actual fluid pressure change amount are appropriate according to the time change. The correct brake fluid pressure can be calculated. Therefore, the brake fluid pressure necessary for stopping the vehicle on the slope can be maintained regardless of the communication delay time or the actual fluid pressure change amount, so that the vehicle can be prevented from slipping.

  (3) Since the idle stop control unit 210 receives the delay hydraulic pressure and calculates the communication delay time of the CAN 250 based on the actual hydraulic pressure and the received delay hydraulic pressure, the communication delay time can be calculated in real time. Therefore, the brake fluid pressure necessary for stopping the vehicle on the slope can be maintained regardless of the time change of the communication delay time, so that the vehicle can be prevented from slipping down.

  (4) Even if communication delay occurs in CAN 250, when the actual hydraulic pressure becomes P2 in the idle stop control unit 210, the corrected brake hydraulic pressure is transmitted so that the delayed hydraulic pressure also becomes P2. Hill hold control can be started when is P2. Therefore, it is not necessary to provide the brake fluid pressure sensor 242 in the ABSCU 220, and the flexibility of layout can be improved and the cost can be reduced.

  As described above, the idle stop control device of the present invention has been described based on the first embodiment. However, the specific configuration is not limited to these embodiments, and the invention according to each claim of the claims is described. Design changes and additions are allowed without departing from the gist. For example, in this embodiment, the idle stop control and the hill hold control are controlled using the brake hydraulic pressure, but may be controlled using the stroke amount of the brake pedal instead.

1 is an overall system diagram showing a drive system, a control system, and a brake system of a continuously variable transmission vehicle equipped with an idle stop control unit. It is a figure explaining the communication delay of CAN based on Example 1. FIG. 6 is a time chart when using a corrected brake fluid pressure according to the first embodiment. It is a figure explaining the correction brake fluid pressure based on Example 1. FIG. 3 is a flowchart illustrating a flow of idle stop control according to the first embodiment.

Explanation of symbols

210 Idle stop control unit 220 Anti-lock brake system control unit (ABSCU)
242 Brake fluid pressure sensor 250 Control area network (CAN)

Claims (3)

A braking force detection device that detects the braking force and outputs it as braking force information;
A hill hold control device that holds the braking force required when the vehicle stops on a slope,
An idle stop control device that automatically stops the engine when the vehicle is stopped and automatically starts when the brake force information reaches a predetermined value or less;
In an idle stop control system with
The brake force detection device is connected to the idle stop control device,
The idle stop control device is connected to the hill hold control device by a communication line,
An idle stop control system comprising correction means for correcting the brake force information according to a communication delay of the communication line. The idle stop control system according to claim 1,
The correction means includes
First braking force information received from the braking force detection device by the idle stop control device;
Second brake force information received from the idle stop control device by the hill hall control device;
An idle stop control device that calculates a communication delay of the communication line based on The idle stop control device according to claim 2,
The correction means includes
The communication delay;
A change amount of the first brake force information;
A correction brake force information is calculated based on the idle stop control device.

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