JP2011149279A - Control device for idle stop vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To release the hill start control braking force at restart of the engine at an appropriate timing without dragging of braking or slipping down of the vehicle without the need of an operation of sensing the vehicle driving force (creep force) using a force sensor or an operation of sensing the driving force from the engine rotation speed in an idle stop vehicle wherein the belt type CVT operation liquid pressure is formed with a mechanical pump. <P>SOLUTION: If the engine of an idle stop vehicle 1 is stopped automatically when predetermined stopping conditions are satisfied, brake fluid pressure controlling valves 8a, 8b of a solenoid valve group 8 start applying braking force in the case the driving force is lowered by the automatic stoppage. The time from the automatic stoppage of the engine to the timing wherein at least predetermined restart conditions are satisfied is counted with a timer 13b. If the engine is restarted, application of the braking force is released with a control unit 13 at timing according to the time counted by the timer means 13b. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  According to the present invention, an operating hydraulic pressure of a belt type continuously variable transmission is formed by a mechanical pump, the engine is automatically stopped when a predetermined stop condition is satisfied, and the engine is restarted when a predetermined restart condition is satisfied. More specifically, the present invention relates to prevention of vehicle slippage when the engine is restarted.

  Conventionally, in a vehicle having a belt type continuously variable transmission (CVT), an idle stop function is added to form an idle stop vehicle in order to reduce fuel consumption. When this idle stop vehicle is stopped due to a signal or the like, the engine is automatically stopped on condition that a predetermined stop condition such as a brake pedal being depressed is satisfied. In addition, the engine is automatically restarted when a certain restart condition is established such that the brake pedal is switched to the accelerator pedal during the automatic stop.

  By the way, in a vehicle having a belt-type CVT, if a mechanical pump (mechanical oil pump) that operates with engine output is provided, the operation of the mechanical pump stops when the engine automatically stops. The operating hydraulic pressure, in other words, the belt clamping pressure of the CVT belt is lowered and the clutch is disengaged. In this state, the clutch meet timing is delayed when the engine is restarted, causing a delay in starting, or problems such as belt slip of the CVT belt.

  Thus, in this type of idle stop vehicle, it has been proposed to add an electric pump (electric oil pump) for continuing to clamp the CVT belt even after the engine is restarted. An additional pump is required.

  It has also been proposed to take measures to prevent fluid leakage (oil leakage) so that the clutch fluid pressure (the working fluid pressure) in the engine is less likely to decrease without adding an electric pump. In this case, although an electric pump is not required, the amount of liquid leakage gradually increases according to the idle stop duration from the automatic stop to restart of the engine, and the clutch meet timing at the time of restart of the engine is delayed. That is, the clutch meet timing when the engine is restarted changes according to the idle stop duration. For this reason, it becomes difficult to optimally control the braking force of hill start control (hill start assist) on hills determined by the balance with creep force, and when the engine is restarted on hills, the brakes are applied. Brake drag and vehicle drag may occur.

  In an idle stop vehicle that forms the operating fluid pressure of the automatic transmission with a mechanical pump, when the engine is restarted, the driving force (creep force) of the vehicle is detected by a force sensor arranged in the transmission system. In order to prevent the vehicle from sliding down when the engine is restarted on a hill, etc., the brake force is reduced according to the recovery of the driving force of the vehicle by hill start control (hill hold control). (See, for example, Patent Document 1 (abstract, paragraphs [0108]-[0110], FIG. 1, FIG. 6, FIG. 7, etc.)).

JP 2000-313253 A

  In an idle stop vehicle that generates a belt type CVT operating fluid pressure by a mechanical pump, as described in Patent Document 1, when the engine is restarted, the braking force is adjusted to the recovery state of the driving force (creep force) of the vehicle. It may be possible to prevent dragging of the brake or falling of the idle stop vehicle on a slope, but in this case, if a force sensor is installed in the transmission system to detect the creep force, the problem becomes expensive. There is. Further, when a belt-type CVT is provided as an automatic transmission, it is necessary to obtain the necessary creep force in consideration of the degree of belt clamping pressure of the CVT belt, etc., so it is difficult to detect the creep force from the engine speed. It is.

  The present invention can detect a driving force (creep force) of a vehicle using a force sensor and detect a driving force from an engine rotational speed in an idle stop vehicle in which a hydraulic pressure of a belt type CVT is formed by a mechanical pump. The purpose of this is to release the braking force of the hill start control at an appropriate timing without dragging of the brake or sliding down of the vehicle.

  In order to achieve the above-described object, the control device for an idle stop vehicle according to the present invention forms the operating hydraulic pressure of the belt type CVT with a mechanical pump, automatically stops the engine when a predetermined stop condition is satisfied, A control device for an idle stop vehicle that automatically restarts the engine when a restart condition is satisfied, and a brake applying means that starts applying the braking force when the driving force is reduced due to the automatic stop of the engine; A timing means for timing the time from when the engine is automatically stopped until at least the predetermined restart condition is satisfied, and timing based on the timing time of the timing means when the automatically stopped engine is restarted. Brake releasing means for releasing the application of the braking force of the brake applying means is provided (claim 1).

  In the case of the first aspect of the invention, when a predetermined stop condition is satisfied by waiting for a signal or the like and the engine automatically stops, the brake applying means applies the braking force when the driving force of the vehicle is reduced by the automatic stop. Therefore, even if the driver removes his / her foot from the brake pedal in order to switch to the accelerator pedal on a hill or the like, the idle stop vehicle does not fall off. Further, the time from the automatic stop of the engine until at least a predetermined restart condition is satisfied is measured by the time measuring means. Then, when the engine is restarted, the application of the braking force of the brake applying means is released at a timing corresponding to the time counted by the time measuring means.

  In this case, since the application of the braking force by the brake applying means is released in accordance with the clutch meet timing that changes according to the time until the engine that has been automatically stopped is restarted, the driving force (creep force) using the force sensor is released. ) And the detection of the driving force from the engine speed, the release of the braking force of the hill start control can be performed in accordance with the clutch meet timing at which the driving force recovers when the engine is restarted. . Therefore, when the engine of an idle stop vehicle is restarted on a hill or the like, the brake force of the hill start control can be released at an appropriate timing that does not cause the dragging of the brake or the sliding down of the idle stop vehicle. The reliability of the hill start of the idle stop vehicle that forms the operating fluid pressure of the belt type CVT by the pump is improved with an inexpensive and simple configuration.

  The timing at which the brake applying means starts to apply the braking force may be the timing at which the engine automatically stops, the timing at which the engine is restarted thereafter, and further from the brake pedal to restart the engine. It may be a timing at which the master cylinder pressure actually starts to drop due to the foot being released. In short, the brake applying means may apply the braking force when the driving force of the idle stop vehicle is reduced due to the automatic stop of the engine.

It is a block diagram of one embodiment of the present invention. It is explanatory drawing of the operation | movement of FIG. 1, (a) is an example of the hydraulic pressure of CVT, (b), (c) is the time to rise to the hydraulic pressure of the clutch meat with respect to the engine restart timing, and release of the braking force It is explanatory drawing of the example of a change of each time to do. It is a flowchart for operation | movement description of FIG.

  Next, in order to describe the present invention in more detail, an embodiment will be described in detail with reference to FIGS.

  FIG. 1 shows a configuration related to idle stop and hill start of an idle stop vehicle 1 to which the present invention is applied, 2 is a brake pedal, 3 is a master cylinder to which the pedal force of the brake pedal 2 is applied via a brake booster 4, Is a pipe connected to the master cylinder 3, and 6 is a hydraulic pressure sensor attached to the pipe 5, which detects the master cylinder pressure. A brake actuator 7 includes a hydraulic pressure sensor 6 and a solenoid valve group 8. The solenoid valve group 8 is composed of a plurality of solenoid valves including brake hydraulic pressure control valves 8a and 8b as brake applying means of the present invention. The brake fluid pressure control valves 8a and 8b are provided for each of the two systems branched from the pipe 5, and are also used for control of hill start control for idle stop and brake control for ESC and TCS during traveling. 9FL and 9FR are the left and right front wheel cylinders of the idle stop vehicle 1, and 9RL and 9RR are the left and right rear wheel cylinders of the idle stop vehicle 1, for example, one piping extending from the brake fluid pressure control valve 8a. The left front wheel cylinder 9FL and the right rear wheel cylinder 9RR are connected to 10FL and 10RR, and the right front wheel cylinder 9FR and the left rear wheel are connected to the other piping 10FR and 10RL extending from the brake fluid pressure control valve 8b. Cylinder 9RL is connected.

  Next, an in-vehicle network 11 such as a CAN (Control Area Network) is disposed in the idle stop vehicle 1. The in-vehicle network 11 includes an idle stop control unit (eco-run control unit) 12, and a brake control unit 13 in the brake actuator 7. , An ECU such as an engine control unit 14, a transmission control unit (CVT control unit) 15, a rudder angle sensor 16, a yaw rate sensor 17, a vehicle speed meter 18, etc. are connected, and these ECUs exchange information via the in-vehicle network 11. To do. Each ECU is formed by a microcomputer. The engine control unit 14 controls the throttle opening of an engine (not shown), and the transmission control unit 15 is a belt type CVT (not shown) connected to the engine via a torque converter (not shown). ) To control.

  Next, the idle stop control unit 12, the brake control unit 13, and the like are usually supplied with power from a vehicle-mounted 12 V battery 19 in the same manner as other units. The idle stop control unit 12 includes a booster circuit 12a as a backup power source. The booster circuit 12a boosts the power supply of the battery 19 when the engine is stopped, etc., and the idle stop control unit 12, the brake control unit 13, etc. necessary for restarting the engine, etc. Supply the boosted power to the required control unit.

  Also, the brake control unit 13 selects the higher one of the power supply voltage from the battery 19 and the power supply voltage from the booster circuit 12a by the built-in OR circuit 13a, and operates with the selected power supply.

  Therefore, the brake control unit 13 boosts the boosted circuit 12a in the boosting circuit 12a during the restart of the engine in the idle stop where the voltage of the battery 19 may greatly decrease, particularly in the cranking period until the engine is completely detonated. The power supply is compensated for by the power supply and it operates reliably, and the hill start control is reliably controlled when the engine is restarted.

  The idle stop control unit 12 and the brake control unit 13 will be further described.

  The idle stop control unit 12 collects information such as the master cylinder pressure detected by the hydraulic pressure sensor 6 and the vehicle speed of the meter 16 based on communication via the in-vehicle network 11 while the idle stop vehicle 1 is traveling. Then, when waiting for a signal or the like, when the accelerator pedal is switched to the brake pedal and a predetermined stop condition (idle stop condition) such as a decrease in the vehicle speed is satisfied, the idle stop control unit 12 is connected to the in-vehicle network 11. The engine stop of idle stop is notified to the brake control unit 13 and the engine control unit 14 via

  When the driver depresses the brake pedal 2, the braking force of the master cylinder pressure is applied to the wheel cylinders 9FL to 9RR, and the traveling of the idle stop vehicle 1 is stopped. At this time, since the driving force of the idle stop vehicle 1 is reduced by the automatic stop of the engine, which will be described later, in the case of this embodiment, the hill start control is controlled at the timing at which the engine automatically stops. Then, the brake control unit 13 controls the brake fluid pressure control valves 8a and 8b of the solenoid valve 8 to hold the brake force of each of the wheel cylinders 9FL to 9RR, and applies a sufficient brake force to each of the wheel cylinders 9FL to 9RR. . Further, the engine fuel throttle of the engine is throttled by the engine control unit 14 to automatically stop the engine, and the idle stop vehicle 1 enters the idle stop state.

  Thereafter, when the driver switches from the brake pedal to the accelerator pedal on the basis of a change from red to blue of the traffic light, the stop lamp switch 20 changes from a lighted on signal to a lighted off signal. Further, the detected master cylinder pressure of the hydraulic pressure sensor 6 via the in-vehicle network 11 decreases to a predetermined pressure or less. When a predetermined restart condition of the engine including both or one of them is satisfied, the idle stop control unit 12 instructs the brake control unit 13 and the engine control unit 14 to restart the engine, and controls the engine control unit 14. The engine restarts.

  On the other hand, the brake control unit 13 is controlled by software by means of known ABS (anti-lock brake system) control means, TCS (traction control system) control means, ESC (side slip prevention) control means, hill start control control means. And a timer 13b as a time measuring means of the present invention and a brake releasing means of the present invention to be described later.

  When a predetermined stop condition is satisfied and the brake control unit 13 receives a notification of engine stop for idling stop, the timer 13b is activated and starts counting time.

  By the way, when a predetermined stop condition is satisfied and the engine automatically stops, the mechanical pump that operates at the output also stops operating, and even if measures for preventing liquid leakage (oil leakage) are taken, the operating fluid pressure ( The belt clamping pressure of the CVT belt) gradually decreases as the stop time elapses.

  FIG. 2A shows an example of a decrease in operating fluid pressure of the belt type CVT. The operating fluid pressure of the belt type CVT is a predetermined pressure P0 during the operation of the engine, and gradually decreases from the engine stop time t1. Further, when the engine is restarted at the subsequent time t2 and the mechanical pump operates, the operating fluid pressure of the CVT gradually increases and returns to the predetermined pressure P0. As the difference ΔP between the predetermined pressure P0 indicated by the arrow line in the drawing and the current pressure increases, it takes time for the operating fluid pressure of the CVT to return to the predetermined pressure P0 when the engine is restarted.

  FIG. 2 (b) shows an example of a change in the time from when the engine fluid pressure is increased to the fluid pressure at the clutch meat with respect to the idle stop duration. As the start timing (time t2) is delayed, the time until the operating fluid pressure of the CVT is increased to the fluid pressure of the clutch meat increases.

  Therefore, when the engine is restarted, the valve solenoids of the respective wheel cylinders 9FL to 9RR are opened after the engine reaches a set rotational speed (several hundred rpm) including the complete explosion rotation after a predetermined restart condition is satisfied, Even if the brake force is released, depending on the idle stop duration until then, the release of the brake force may be delayed from the timing of the clutch meet, the brake may be dragged, or the timing before the clutch meet (that is, driving) There is a possibility that the braking force is released before the force (creeping force is restored), and the idling stop vehicle 1 slips down, impairing the reliability of the hill start.

  Therefore, at least when a predetermined restart condition is satisfied, the brake control unit 13 stops the timer 13b, and the timer 13b measures the time on the vertical axis of FIG. 2B. Furthermore, the timing based on the time measured by the timer 13b is set as a timing for releasing the application of the braking force for idling stop, and at this timing, the brake hydraulic pressure control valves 8a and 8b of the solenoid valve group 8 are controlled to be reduced by the brake releasing means. Then, the brake fluid pressure control valves 8a and 8b are opened, and the brake force applied to the wheel cylinders 9FL to 9RR is released.

  Note that the timing at which the timer 13b stops timing is the timing at which a predetermined restart condition is satisfied, but in some cases, the timing at which the engine reaches the set rotational speed after the predetermined restart condition is satisfied. May be.

  In addition, it is practically preferable that the timing for releasing the application of the braking force is a timing at which the engine reaches the set rotational speed after the predetermined restart condition is satisfied and the time measured by the timer 13b has elapsed. Depending on conditions and the like, the timing at which the time measured by the timer 13b has passed since the establishment of a predetermined restart condition may be used.

  The engine speed is detected by the engine control unit 14 and sent from the engine control unit 14 to the brake control unit 13 or the like via the in-vehicle network 11.

  In order to set the timing based on the time measured by the timer 13b as the timing for releasing the application of the braking force for idling stop, the timing for the brake control unit 13 to release the application of the braking force by controlling the master cut solenoid valve 8 to reduce the pressure. Varies depending on the idle stop duration. Therefore, even when the idle stop duration becomes long, the timing for releasing the braking force is at least a predetermined restart condition, after the time measured by the timer 13b corresponding to the idle stop duration has elapsed. It is possible to match the timing of the clutch meat when the engine driving force (creep force) is restored.

  FIG.2 (c) shows the example of a change based on the restart timing of the time from the restart of an engine to the start of the said pressure reduction, and the time t2 which is a restart timing becomes late | slow, so that idle stop duration time becomes long, The time from the restart of the engine to the start of the decompression becomes longer.

  Then, the brake fluid pressure control valves 8a and 8b of the solenoid valve group 8 are controlled to be depressurized, and the timing for releasing the braking force is the timing corresponding to the idle stop duration, and is applied to each of the wheel cylinders 9FL to 9RR. Since the release timing of the brake force that has been performed can be matched with the timing of the clutch meet, the brake drag due to the release delay of the brake force does not occur regardless of the length of the idle stop duration. In addition, since the braking force is not released before the timing of the clutch meet, there is no slipping down of the idle stop vehicle 1 on a slope or the like, and the reliability of the hill start is improved.

  FIG. 3 shows an example of control for applying and releasing the braking force of the above-described idle stop in the brake control unit 13. First, when a predetermined stop condition is satisfied while the idle stop vehicle 1 is running and the engine automatically stops, Pass S1 with affirmative (YES). Then, the valve solenoids of the respective wheel cylinders 9FL to 9RR are closed, and the braking force is applied to the respective wheel cylinders 9FL to 9RR so that an idle stop state is set (step S2). At this time, the timer 13b starts measuring time (step S3).

  Next, when a predetermined restart condition is established during the idle stop, step S4 in FIG. 3 is passed in an affirmative (YES), the timer 13b is stopped, and the braking force is applied based on the timer 13b. The release timing is determined (step S5).

  Then, the determined release timing is waited (No in step S6 (NO)). When the release timing is reached, step S6 is passed in an affirmative manner and the valve solenoids of the wheel cylinders 9FL to 9RR are opened to release the brake force. To do. Thereafter, normal brake control is performed.

  As described above, in the present embodiment, the brake fluid pressure control valves 8a and 8b of the solenoid valve group 8 form the brake applying means of the present invention, and the brake control unit 13 is the time measuring means and brake releasing means of the present invention. If the engine of the idle stop vehicle 1 is automatically stopped due to a signal or the like and the idle stop vehicle 1 may slip down when the engine is subsequently restarted, the automatic stop is responded to. The brake applying means applies a braking force. Therefore, when the engine is restarted, the idle stop vehicle 1 does not fall down even on a slope. Further, the time from the automatic stop of the engine until at least the predetermined restart condition is satisfied is timed by the time measuring means, and when the engine is restarted, the braking force of the brake applying means is at a timing according to the time measured by the time measuring means. The application of the braking force by the brake applying means can be canceled in accordance with the clutch meet timing that changes depending on the time until the engine is restarted.

  Therefore, without detecting the driving force (creep force) of the vehicle using a force sensor or detecting the driving force from the engine rotation speed, the brake force of the hill start control is released when the engine is restarted. In accordance with the clutch meet timing at which the driving force (creep force) of the stop vehicle 1 recovers, it can be carried out at an appropriate timing without brake dragging or vehicle dragging, and the hydraulic pressure of the belt type CVT can be adjusted by a mechanical pump. The certainty of the hill start of the idle stop vehicle to be formed can be improved with an inexpensive and simple configuration.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. Even when the predetermined stop condition is satisfied, it may be the timing when the vehicle speed is actually zeroed and then stopped. Further, the timing when the timer 13b finishes timing may be the timing when a predetermined restart condition is satisfied, or the timing when the engine speed subsequently reaches a certain rotational speed including the complete explosion speed.

  Next, the timing for starting the application of the braking force is not limited to the timing of automatic engine stop as in the above-described embodiment, and it is considered that the driver continues to step on the brake pedal while the engine is stopped. The timing at which the restart condition is satisfied, the timing at which the brake fluid pressure actually starts to decrease due to the release of the foot from the brake pedal after the restart condition is satisfied, etc. Any timing may be used as long as it can prevent the idle stop vehicle 1 from slipping down. Further, the timing for releasing the application of the braking force may be a timing delayed by the time measured by the timer 13b from the timing when the predetermined restart condition is satisfied, and the engine speed is constant after the predetermined restart condition is satisfied. It may be a timing delayed by the time measured by the timer 13b from the timing at which the rotation speed is reached. These timings may be set to the most preferable timing based on experiments or the like.

  Moreover, what kind and number of control units etc. may be connected to the in-vehicle network 11, and the in-vehicle network 11 is not limited to CAN. Further, the piping configuration of the brake actuator 7 and the cylinders 9FL to 9RR may be any.

  The present invention can be applied to various idle stop vehicles in which the operating hydraulic pressure of the belt type continuously variable transmission is generated by a mechanical pump.

DESCRIPTION OF SYMBOLS 1 Idle stop vehicle 8 Solenoid valve group 8a, 8b Brake fluid pressure control valve 12 Idle stop control unit 13 Brake control unit 13b Timer 14 Engine control unit 15 Transmission control unit

Claims (1)

An idle stop that forms the operating hydraulic pressure of a belt-type continuously variable transmission with a mechanical pump, automatically stops the engine when a predetermined stop condition is satisfied, and automatically restarts the engine when the predetermined restart condition is satisfied A vehicle control device,
Brake application means for starting application of braking force when the driving force is reduced due to the automatic stop of the engine;
Clocking means for timing the time from when the engine automatically stops until at least the predetermined restart condition is satisfied;
Brake release means for releasing the brake force applied by the brake applying means at a timing based on the time measured by the time measuring means when the automatically stopped engine is restarted. Control device.

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