JP4877121B2 - Idle stop control device for vehicle - Google Patents

Description

  The present invention belongs to the technical field of an idle stop control device for a vehicle.

Some conventional vehicle idle stop control devices shift to an idle stop that automatically stops the engine when the vehicle speed falls below a certain threshold before the vehicle speed becomes zero. In other words, it is not the lowest vehicle speed that can be detected by the wheel speed sensor (≒ 0km / h), but the driver's intention to stop when the vehicle speed is higher than this lowest vehicle speed, and the engine is automatically stopped to improve fuel efficiency. (For example, refer to Patent Document 1).
JP 2006-183546 A

  However, in the above prior art, since the engine is automatically stopped before the vehicle is completely stopped, the vehicle speed is equal to or less than the threshold value when the driver is performing the gentle braking for stopping the vehicle while traveling on the uphill road. Then, after the engine has stopped, when the braking force is equal to or lower than the descent force due to the vehicle's own weight when the vehicle has completely stopped, there has been a problem that the vehicle will slide down.

  The present invention has been made paying attention to the above problems, and an object of the present invention is to provide a vehicle idle stop control device capable of achieving both improvement in fuel efficiency and prevention of slipping down on an uphill road. It is in.

  In order to achieve the above-mentioned object, the present invention sets the idle stop transition condition vehicle speed threshold value to a smaller value as the road surface gradient increases during traveling on an uphill road.

In the present invention, the driving force is maintained until the vehicle is completely stopped as the road surface gradient increases. That is, since the engine is stopped in a state in which the braking force has risen as the road surface gradient increases, it is possible to prevent the vehicle from slipping down due to insufficient braking force when shifting from gentle braking to idle stop on an uphill road. On the other hand, when the road surface gradient is small and there is no risk of slipping due to insufficient braking force, the engine can be stopped earlier and fuel consumption can be improved.
As a result, it is possible to achieve both improvement in fuel efficiency and prevention of sliding down on an uphill road.

Hereinafter, the best mode for carrying out the present invention will be described based on the first embodiment.

  First, the drive system configuration of the hybrid vehicle will be described. FIG. 1 is an overall system diagram showing a hybrid vehicle driven by rear wheels of the first embodiment. As shown in FIG. 1, the drive system of the hybrid vehicle in the first embodiment includes an engine E, a flywheel FW, a motor generator MG, a clutch CL, an automatic transmission AT, a propeller shaft PS, and a differential DF. The left drive shaft DSL, the right drive shaft DSR, the left rear wheel RL (drive wheel), and the right rear wheel RR (drive wheel). Note that FL is the left front wheel and FR is the right front wheel.

  The engine E is a gasoline engine or a diesel engine, and the valve opening degree of the throttle valve and the like are controlled based on a control command from an engine controller 1 described later. The engine output shaft is provided with a flywheel FW.

  The motor generator MG is a synchronous motor generator in which a permanent magnet is embedded in a rotor and a stator coil is wound around a stator, and the three-phase AC generated by the inverter 3 is generated based on a control command from a motor controller 2 described later. It is controlled by applying. The motor generator MG can operate as an electric motor that is driven to rotate by receiving power supplied from the battery 4 (hereinafter, this state is referred to as “power running”), or when the rotor is rotated by an external force. Can function as a generator that generates electromotive force at both ends of the stator coil to charge the battery 4 (hereinafter, this operation state is referred to as “regeneration”). The rotor of the motor generator MG is connected to the input shaft of the automatic transmission AT via a damper (not shown).

  The clutch CL is a clutch interposed between the motor generator MG and the left and right rear wheels RL and RR, and is controlled by a control hydraulic pressure generated by the clutch hydraulic unit 8 based on a control command from the AT controller 7 described later. The fastening and releasing are controlled including slip fastening and slip releasing.

  The automatic transmission AT is a transmission that automatically switches the stepped gear ratio such as 5 forward speeds, 1 reverse speed, etc. according to the vehicle speed, accelerator opening, etc., and the clutch CL is newly added as a dedicated clutch Instead, several frictional engagement elements are used among a plurality of frictional engagement elements that are engaged at each gear stage of the automatic transmission AT. Details will be described later.

  The output shaft of the automatic transmission AT is connected to the left and right rear wheels RL and RR via a propeller shaft PS, a differential DF, a left drive shaft DSL, and a right drive shaft DSR. The clutch CL uses, for example, a wet multi-plate clutch that can continuously control the oil flow rate and hydraulic pressure with a proportional solenoid.

  In this hybrid drive system, a traveling mode in which the power of the engine E and the power of the motor generator MG is combined is used as a power source, and only the power of the engine E is used as a power source, and the motor generator MG functions as a generator. Switch between driving modes.

  Next, the control system of the hybrid vehicle will be described. As shown in FIG. 1, the control system of the hybrid vehicle in the first embodiment includes an engine controller 1, a motor controller 2, an inverter 3, a battery 4, an AT controller 7, a clutch hydraulic unit 8, and a brake controller 9. And an integrated controller 10. The engine controller 1, the motor controller 2, the AT controller 7, the brake controller 9, and the integrated controller 10 are connected to each other via a CAN communication line 11 that can exchange information.

  The engine controller 1 inputs the engine water temperature from the engine water temperature sensor 1a and the engine speed information from the engine speed sensor 12, and according to the target engine torque command from the integrated controller 10 or the like, the engine operating point (engine speed) A command for controlling Ne, engine torque Te) is output to, for example, a throttle valve actuator (not shown). Information on the engine speed Ne is supplied to the integrated controller 10 via the CAN communication line 11.

  The motor controller 2 inputs information from the resolver 13 that detects the rotor rotational position of the motor generator MG, and according to a target motor generator torque command from the integrated controller 10, the motor operating point of the motor generator MG (motor rotational speed Nm). , A command for controlling the motor torque Tm) is output to the inverter 3. The motor controller 2 monitors the battery SOC indicating the state of charge of the battery 4. The battery SOC information is used as control information for the motor generator MG and is supplied to the integrated controller 10 via the CAN communication line 11. To do.

  The AT controller 7 inputs sensor information from the accelerator opening sensor 16, the vehicle speed sensor 17, and the clutch hydraulic pressure sensor 18, and issues a command for controlling the engagement / release of the clutch CL according to the clutch control command from the integrated controller 10. Output to the clutch hydraulic unit 8 in the AT hydraulic control valve. Information on the accelerator pedal opening APO and the vehicle speed VSP is supplied to the integrated controller 10 via the CAN communication line 11.

  The brake controller 9 inputs sensor information from a wheel speed sensor 19 and a brake stroke sensor 20 that detect the wheel speeds of the four wheels. For example, when the brake is depressed, braking is performed with respect to the required braking force obtained from the brake stroke BS. When the braking force alone is insufficient, the brake units (braking force increasing means) BUFL, BUFR, provided on each wheel based on the regenerative cooperative control command from the integrated controller 10 so that the insufficient amount is compensated by the friction braking force. Regenerative cooperative brake control that drives BURL and BURR is performed.

  As each brake unit BUFL, BUFR, BURL, BURR, a so-called brake-by-wire system electrically connected to a brake pedal (not shown) operated by the driver is used. As a result, a desired friction braking force can be generated regardless of the brake pedal depression amount of the driver.

  The integrated controller 10 manages the energy consumption of the entire vehicle and has a function for running the vehicle with the highest efficiency. The motor controller 21 detects the motor rotation speed Nm (= ωmg), and the clutch output rotation. Information from a clutch output speed sensor 22 for detecting the number Nout, a clutch torque sensor 23 for detecting the clutch torque TCL, a brake hydraulic pressure sensor 24, and a gradient sensor (road surface gradient detecting means) 25 for detecting a road surface gradient, and Information obtained via the CAN communication line 11 is input.

  The integrated controller 10 controls the operation of the engine E according to the control command to the engine controller 1, the operation control of the motor generator MG based on the control command to the motor controller 2, and the engagement / release of the clutch CL based on the control command to the AT controller 7. Control.

  Further, the integrated controller 10 executes idle stop for automatically stopping and automatically restarting the engine E based on a predetermined idle stop condition including a driver's brake operation and the vehicle speed being equal to or lower than the idle stop transition condition vehicle speed threshold value. To do.

  FIG. 2 is a block diagram of the idle stop control according to the first embodiment. The integrated controller 10 includes an idle stop control unit 10a and a vehicle speed threshold setting unit (vehicle speed threshold setting means) 10b.

  The idle stop control unit 10a is configured based on the detection value of the brake stroke sensor 20 input via the brake controller 9 and the signal from the detection value of the vehicle speed sensor 17 input via the AT controller 17. A command for automatically stopping or restarting the engine E is output to the controller 1.

  The vehicle speed threshold value setting unit 10b sets an idle stop transition condition vehicle speed threshold value for determining whether an idle stop condition that is an idle stop start condition is satisfied based on a detection value of the gradient sensor 25 when traveling on an uphill road.

Details of the idle stop control of the first embodiment will be described below.
[Idle stop control processing]
FIG. 3 is a flowchart showing the flow of the idle stop control process on the uphill road executed by the integrated controller 10 of the first embodiment, and each step will be described below. This control process is repeatedly executed every predetermined calculation cycle.

  In step S1, the idle stop control unit 10a determines whether or not idle stop is permitted. Specifically, when the engine water temperature detected by the engine water temperature sensor 1a is equal to or higher than a predetermined value and the battery SOC indicating the charging state of the battery 4 is equal to or higher than the predetermined value, the idle stop permission state is set. If yes, then go to step S2, if no, go to return.

  In step S2, the idle stop control unit 10a inputs a signal from the brake stroke sensor 20, and determines whether the brake is ON, that is, whether the driver is operating the brake. If yes, then go to step S2, if no, go to return.

  In step S3, the vehicle speed threshold setting unit 10b executes an idle stop transition condition vehicle speed threshold calculation process for calculating the vehicle speed threshold, and the process proceeds to step S4. The idle stop transition condition vehicle speed threshold value calculation process will be described later.

  In step S4, the idle stop control unit 10a inputs a signal from the vehicle speed sensor 17, and determines whether or not the vehicle speed is equal to or less than the vehicle speed threshold value calculated in step S3. If YES, the process proceeds to step S5. If NO, the process proceeds to return.

  In step S5, the idle stop control unit 10a outputs a command to stop the engine E to the engine controller 1, and the process proceeds to step S6.

  In step S6, the idle stop control unit 10a inputs a signal from the brake stroke sensor 20, and determines whether the brake is OFF, that is, whether the driver has released the brake operation. If YES, the process moves to step S8, and if NO, the process moves to step S7.

  In step S7, the idle stop control unit 10a determines whether or not the idle stop permission state is set as in step S1. If YES, the process proceeds to step S5. If NO, the process proceeds to step S8.

  In step S8, the idle stop control unit 10a outputs a command to restart the engine E to the engine controller 1 and shifts to return.

[Idle stop transition condition vehicle speed threshold calculation processing]
FIG. 4 is a flowchart showing the flow of the idle stop transition condition vehicle speed threshold value calculation process executed in step S3 of FIG. 3, and each step will be described below.

  In step S11, the vehicle speed threshold setting unit 10b inputs a sensor value from the gradient sensor 25, and determines whether or not the gradient sensor 25 is normal (corresponding to an abnormality determination unit). If YES, the process proceeds to step S12. If NO, the process proceeds to step S13. Here, as an abnormality determination method of the gradient sensor 25, for example, an abnormality determination threshold value of the gradient sensor 25 obtained in advance by an experiment or the like is compared, and when the sensor value is equal to or less than the abnormality determination threshold value, it is normal. There is a method for determining that the sensor value is abnormal when the sensor value exceeds the abnormality determination threshold.

  In step S12, the vehicle speed threshold setting unit 10b sets the vehicle speed threshold with reference to the table shown in FIG. 5 based on the gradient sensor value input in step S11, and the present control is terminated. In the gradient-vehicle speed threshold table of FIG. 5, the vehicle speed threshold is constant 10 km / h when the road gradient is 5 deg or less, and gradually decreases as the road gradient increases when the road gradient is greater than 5 deg and less than 10 deg. The road slope is set to be a constant 5km / h at 10deg or more.

  In step S13, the vehicle speed threshold setting unit 10b sets the vehicle speed threshold to a value on a flat road (a value corresponding to a gradient of 0 deg, for example, a vehicle speed of 10 km / h or more), and this control is terminated.

Next, the operation will be described.
[Idle stop condition change action according to road surface gradient]
If the brake pedal is slowly depressed to stop the vehicle while driving on an uphill road while idling stop is permitted, until the vehicle speed falls below the vehicle speed threshold set in step S3 In the flowchart of FIG. 3, the flow of steps S1 → S2 → S3 → S4 is repeated. Here, the idling stop transition condition vehicle speed threshold set in step S3 is set to a smaller value as the road surface gradient detected by the gradient sensor 25 is larger.

  When the vehicle speed is lower than the idle stop transition condition vehicle speed threshold and the idle stop condition is satisfied, the process proceeds from step S4 to step S5 to shift to idle stop, and the engine E is automatically stopped. Become.

  At this time, the descending force due to the vehicle's own weight increases as the road surface gradient increases. In the first embodiment, the engine E can be stopped in a state where the braking force rises as the road surface gradient increases. As a result, when shifting from slow braking to idle stop on an uphill road, it is possible to prevent the vehicle from sliding down due to insufficient braking force. On the other hand, when the road surface gradient is small and there is no risk of slipping due to insufficient braking force, the engine can be stopped earlier, so that fuel efficiency can be improved.

  During the idle stop, the process of step S5 → step S6 → step S7 is repeated until the idle stop condition is not satisfied, that is, until the idle stop release condition is satisfied, and the engine stop is maintained. And, when the driver releases his / her foot from the brake pedal during idle stop, or when idle stop is not permitted due to a decrease in engine water temperature or battery SOC, the idle stop release condition is satisfied. From step S6 or step S7 to step S8, the engine E is restarted and the idle stop is released.

Next, the effect will be described.
In the vehicle idle stop control apparatus of the first embodiment, the gradient sensor 25 that detects the magnitude of the road surface gradient, and when traveling on an uphill road, the greater the detected road surface gradient, the smaller the idle stop transition condition vehicle speed threshold value. A vehicle speed threshold setting unit 10b that sets the value. As a result, it is possible to achieve both improvement in fuel consumption and prevention of sliding down on an uphill road.

  An abnormality determination means (step S11) for determining abnormality of the gradient sensor 25 is provided, and the vehicle speed threshold setting unit 10b fixes the idle stop transition condition vehicle speed threshold equivalent to a flat road when the gradient sensor 25 is determined to be abnormal. A value (a value corresponding to a gradient of 0 deg, for example, a vehicle speed of 10 km / h or more). Thereby, it is possible to avoid setting an inappropriate idle stop transition condition vehicle speed threshold value due to a sensor abnormality.

Reference example 1

The reference example 1 is an example in which the braking force increase amount during the idling stop is increased as the road surface gradient of the uphill road is larger in a vehicle capable of giving the braking force increase amount to the braking force according to the brake depression amount of the driver. It is.
The overall system is the same as that of the first embodiment shown in FIG. Further, in Reference Example 1 , the idling stop transition condition vehicle speed threshold value is set to a constant value (for example, 10 km / h) regardless of the road surface gradient.

FIG. 6 is an idle stop control block diagram of Reference Example 1. The integrated controller 10 includes an idle stop control unit 10a and a braking force increase amount setting unit (braking force increase amount setting means) 10c.

  The idle stop control unit 10a receives the detection value of the brake stroke sensor 20 input via the brake controller 9, the detection value of the vehicle speed sensor 17 input via the AT controller 17, and the signal from the idle stop SW 26. Based on this, a command to automatically stop or restart the engine E is output to the engine controller 1. Moreover, the idle stop control part 10a outputs the instruction | command which performs a driver | operator's brake assist with respect to the brake controller 9 during an idle stop.

  The braking force increase amount setting unit 10c shifts to idle stop on an uphill road, and when the engine E automatically stops, the braking force increase amount setting unit 10c applies a braking force according to the brake depression amount of the driver based on the detected value of the gradient sensor 25. Set the braking force increase amount.

[Idle stop control processing]
FIG. 7 is a flowchart showing the flow of idle stop control processing on an uphill road executed by the integrated controller 10 of Reference Example 1 , and each step will be described below. In addition, the same step number is attached | subjected to the step which performs the process same as Example 1 shown in FIG. 3, and description is abbreviate | omitted.

  In step S21, the braking force increase amount setting unit 10c executes a braking force increase amount calculation process for calculating the braking force increase amount, and the process proceeds to step S6. The braking force increase amount calculation process will be described later.

  In step S22, the idle stop control unit 10a outputs a command for generating a braking force to which the braking force increase amount calculated in step S21 is added to the brake controller 9, and the process proceeds to step S7.

[Brake force increase calculation processing]
FIG. 8 is a flowchart showing the flow of the braking force increase calculation process executed in step S21 of FIG. 7, and each step will be described below.

  In step S31, the braking force increase amount setting unit 10c inputs a sensor value from the gradient sensor 25, and determines whether or not the gradient sensor 25 is normal. If YES, the process proceeds to step S32. If NO, the process proceeds to step S33.

  In step S32, the braking force increase amount setting unit 10c sets the braking force increase amount with reference to the table shown in FIG. 9 based on the gradient sensor value input in step S31, and this control is terminated. In the gradient-braking force increase amount table of FIG. 9, the braking force increase amount is set so as to increase as the road surface gradient increases.

  In step S33, the braking force increase amount setting unit 10c sets the braking force increase amount to zero and ends the present control.

Next, the operation will be described.
[Brake force change action according to road surface gradient]
If the brake pedal is depressed slowly to stop the vehicle while traveling on an uphill road with idling stop permitted, until the vehicle speed falls below the preset idling stop transition condition vehicle speed threshold, In the flowchart of FIG. 7, the flow of going from step S1 to step S2 to step S4 is repeated.

  If the vehicle speed is below the idle stop transition condition vehicle speed threshold value and the idle stop condition is satisfied, the process proceeds from step S4 to step S5, transitions to idle stop, and the engine E is automatically stopped. Become.

At this time, the descending force due to the vehicle's own weight increases as the road surface gradient increases. In Reference Example 1 , the braking force increase amount is set to a larger value as the road surface gradient increases, and the braking force with respect to the brake depression amount is set. Make it bigger. As a result, when shifting from slow braking to idle stop on an uphill road, it is possible to prevent the vehicle from sliding down due to insufficient braking force. In Reference Example 1 , the idling stop transition condition vehicle speed threshold value is constant regardless of the road surface gradient of the uphill road, so that the idling stop time can be increased and fuel consumption can be improved.

  During the idle stop, the process of step S5 → step S21 → step S6 → step S22 → step S7 is repeated until the idle stop condition is not satisfied, that is, until the idle stop release condition is satisfied. The braking force increase according to the road surface gradient is continued. And, when the driver releases his / her foot from the brake pedal during idle stop, or when idle stop is not permitted due to a decrease in engine water temperature or battery SOC, the idle stop release condition is satisfied. From step S6 or step S7 to step S8, the engine E is restarted and the idle stop is released.

Next, the effect will be described.
In the vehicle idle stop control device of Reference Example 1 , the gradient sensor 25 that detects the magnitude of the road surface gradient, and the brake unit that applies the braking force increase amount to the braking force according to the brake depression amount of the driver. A BUFL, BUFR, BURL, and BURR and a braking force increase amount setting unit 10c that increases the braking force increase amount as the detected road surface gradient increases when the engine E automatically stops on an uphill road. As a result, it is possible to achieve both improvement in fuel consumption and prevention of sliding down on an uphill road.

(Other examples)
Although the best mode for carrying out the invention has been more described in Example 1 based on the drawings, specific configurations of the present invention is not limited to those shown in Example 1, Any design changes that do not change the gist of the invention are included in the present invention.

In Example 1, the engine and the motor-generator as a driving source, but both are described as an example hybrid vehicle which is directly connected to the drive shaft, the present invention may be applied to a vehicle having an engine as at least a driving source Thus, the same effects as those of the first embodiment can be obtained.

In Reference Example 1 , an example in which the brake-by-wire system is used as the braking force increasing means is shown. However, the braking force increasing means gives the braking force increase amount to the braking force according to the brake depression amount of the driver. If possible. For example, in the case of a normal brake unit in which the brake pedal and each wheel cylinder are connected by a hydraulic circuit, a configuration that can supply hydraulic pressure to each wheel cylinder independently of the brake depression amount, such as an ABS unit, or a booster If the structure etc. which can adjust the pressurization rate of an apparatus arbitrarily are added, it can apply as a braking force increase means of this invention.

A configuration in which the first embodiment and the reference example 1 are combined, that is, as the road surface gradient of the uphill road is larger, the idle stop transition condition vehicle speed threshold value is smaller, and as the road surface gradient is larger, the braking force increase amount is larger. Good. As a result, the vehicle is more reliably prevented from sliding down.

1 is an overall system diagram illustrating a hybrid vehicle driven by rear wheels according to a first embodiment. It is an idle stop control block diagram of Example 1. It is a flowchart which shows the flow of the idle stop control process in the uphill road performed with the integrated controller 10 of Example 1. FIG. It is a flowchart which shows the flow of the idle stop transfer condition vehicle speed threshold value calculation process performed by step S3 of FIG. 3 is a gradient-vehicle speed threshold value table of the first embodiment. It is an idle stop control block diagram of the reference example 1 . It is a flowchart which shows the flow of the idle stop control process in the uphill road performed with the integrated controller 10 of the reference example 1. FIG. It is a flowchart which shows the flow of the braking force increase amount calculation process performed by step S21 of FIG. 6 is a gradient-braking force increase amount table of Reference Example 1 ;

E engine
FW flywheel
MG motor generator
CL clutch
AT automatic transmission
PS propeller shaft
DF differential
DSL left drive shaft
DSR right drive shaft
RL Left rear wheel (drive wheel)
RR Right rear wheel (drive wheel)
FL Left front wheel
FR Right front wheel 1 Engine controller 2 Motor controller 3 Inverter 4 Battery 7 AT controller 8 Clutch hydraulic unit 9 Brake controller 10 Integrated controller 24 Brake hydraulic sensor
100 Target driving force calculator
200 Mode selection section
300 Target charge / discharge calculator
400 Operating point command section
500 Shift control

Claims (2)

In a vehicle idle stop control device that automatically stops an engine when a predetermined idle stop condition is satisfied, including a driver's brake operation and a vehicle speed being equal to or less than an idle stop transition condition vehicle speed threshold,
Road surface gradient detecting means for detecting the magnitude of the road surface gradient;
Vehicle speed threshold setting means for setting the idle stop transition condition vehicle speed threshold to a smaller value as the detected road surface gradient is larger when traveling on an uphill road;
An idle stop control device for a vehicle, comprising: The idle stop control device for a vehicle according to claim 1,
An abnormality determination means for determining an abnormality of the road surface gradient detection means,
The vehicle speed threshold value setting means sets the idle stop transition condition vehicle speed threshold value to a fixed value corresponding to a flat road when the road surface gradient detection means is determined to be abnormal.

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