JP2010169174A - Controller of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller of vehicle which can make a fuel cutting range large while utilizing energy during deceleration. <P>SOLUTION: When fuel cutting is controlled, a driving force is applied to an engine by a driving means so that deceleration may not be excessive. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a control device for a vehicle including an engine that performs fuel cut control for stopping fuel injection of the engine.

  As a technique for performing fuel cut control of an engine during coasting, a technique described in Patent Document 1 is known. In this publication, in order to widen the fuel cut region, even if the load on the auxiliary equipment in the low vehicle speed region is reduced and the fuel cut region is widened to the low vehicle speed side, the occurrence of excessive deceleration is suppressed.

JP 2002-248935 A

  However, the technique described in Patent Document 1 has a problem that the energy during deceleration cannot be sufficiently utilized in order to reduce the load on the auxiliary machinery in the low vehicle speed region.

  The present invention has been made paying attention to the above problem, and an object of the present invention is to provide a vehicle control device capable of widening a fuel cut region while utilizing energy during deceleration.

  In order to achieve the above object, in the present invention, a driving force is applied to the engine by the driving means so that the deceleration does not become excessive during the fuel cut control.

  As a result, the fuel cut control region can be expanded without excessive deceleration.

1 is an overall system diagram illustrating a vehicle control apparatus according to a first embodiment. 3 is a flowchart illustrating fuel cut control according to the first embodiment. FIG. 6 is a characteristic diagram illustrating a relationship between a vehicle speed and a deceleration according to the first embodiment.

  FIG. 1 is an overall system diagram showing a vehicle control apparatus according to a first embodiment of the present invention. Reference numeral 10 denotes an engine, and 20 denotes a belt-type continuously variable transmission, which includes a torque converter 22 having a lock-up clutch 21 and an inertia member D that stores inertia energy during deceleration and releases the energy at a predetermined timing. Yes. One of the inertia members D is connected to the crankshaft of the engine 10 via the first clutch C1, and the other is connected to the drive shaft for driving the drive wheels via the second clutch C2. The second clutch C1, C2 constitutes a drive actuator. The driving force of the engine 10 is transmitted not only to the continuously variable transmission 20 but also to the compressor 30 of the air conditioner that is an auxiliary device via the electromagnetic clutch 32. The engine 10 and the continuously variable transmission 20 are controlled by various control signals from the engine / transmission control unit 40.

  The engine / transmission control unit 40 is connected with a brake switch 50 for detecting the braking state, an idle switch (IDLSW) 60 for detecting the coast state, and an accelerator sensor 70 for detecting the amount of depression of the accelerator pedal as inputs. A vehicle speed signal VSP from a vehicle speed sensor 80 provided in the continuously variable transmission is input from the communication line 23, and an engine speed signal Ne from an engine rotation sensor 90 provided in the engine is input from the communication line 11.

  Further, communication lines 24 and 25 for outputting a shift command signal, a lockup command signal, and an engagement command signal for the first and second clutches C1 and C2 to a control valve (not shown) provided in the continuously variable transmission as outputs, A communication line 12 for outputting a fuel injection command signal is connected to an injector (not shown) provided in the engine. The gear ratio of the continuously variable transmission 20 is controlled based on a known control based on the accelerator pedal depression amount, the vehicle speed VSP, and the like. In addition, since it is impossible to change the gear ratio when the vehicle is stopped, it is necessary to increase the gear ratio in preparation for starting in the low vehicle speed range (lowest side). The compressor 30 is controlled by a control signal from the air conditioner control unit 31. The air conditioner control unit 31 mainly controls a known air conditioner by controlling an electromagnetic clutch 32 provided in the compressor 30 based on a signal from an air conditioner switch 33 operated by a driver.

(Fuel cut control process)
FIG. 2 is a flowchart of a fuel cut control process that is always executed at predetermined control intervals while the engine / transmission control unit 40 is traveling. The fuel cut control for stopping the output of the fuel injection command signal is activated when the engine speed is equal to or higher than the predetermined engine speed in the coast state. The coast state is determined by a signal from the idle switch 60 in step S10, and if it is ON, it is determined that it is coasting, and the process proceeds to step 20. The first clutch C1 is turned off, the second clutch C2 is turned off, and a normal fuel injection command signal is output.

  In step 20, it is determined whether or not the vehicle speed VSP exceeds the predetermined vehicle speed V1, and if affirmative, in step S80, the fuel cut control is activated (FC ON), the first clutch C1 is turned off, the second clutch C2 is turned on, If not, the process proceeds to step S30, the fuel cut control is activated, the first clutch C1 is turned on, the second clutch C2 is turned off, and the process proceeds to step S40. In step S40, it is determined whether or not the vehicle speed VSP has reached the vehicle speed V2 corresponding to α which is a rotation speed obtained by adding a predetermined amount to the idle rotation speed α1 on the lowest speed ratio. When the flow is finished and reached, the process proceeds to step S50.

  In step S50, the lockup clutch 21 is released and the process proceeds to step S60. In step S60, it is determined whether or not the engine speed Ne has reached the idle speed α1, and if it has reached, the process proceeds to step S70 to end the fuel cut control, and otherwise the control flow is ended. .

(Operation of drive actuator)
Next, the operation of the drive actuator in the above-described fuel cut control process will be described. The fuel cut control is premised on that even if the fuel injection is stopped, the engine speed is maintained at the idling speed or higher, and the engine torque can be output as soon as the fuel injection is started again. Therefore, the lockup clutch 21 is engaged during fuel cut control, and the inertia energy of the vehicle is transmitted from the drive wheel side to the engine side via the belt type continuously variable transmission 20.

  Here, the belt-type continuously variable transmission 20 is controlled by the vehicle speed VSP and the accelerator pedal depression amount, and is determined by the vehicle speed VSP because the accelerator pedal depression amount is 0 in the coasting state. At this time, the engine speed is also determined by the determined gear ratio and the vehicle speed VSP. At this time, the gear ratio shifts to the low side as the vehicle speed VSP decreases, and the engine speed changes accordingly.

  FIG. 3 is a characteristic diagram showing the relationship between vehicle speed and deceleration. When the gear ratio is shifted to the low side, the engine speed increases and the engine braking force increases accordingly. The gear ratio is generally set in a geometric series, and after a certain vehicle speed V1, the gear ratio suddenly increases to the low side, and the deceleration due to the engine braking force is accompanied accordingly. Also grows rapidly. In addition, auxiliary equipment such as an air conditioner is attached to the engine, and when the engine speed increases, the resistance of these auxiliary equipment also increases, so there is a sense of incongruity due to excessive deceleration.

  Although it is conceivable that the gear ratio is not shifted too low in order to avoid an increase in the engine speed, in the case of a belt type continuously variable transmission, the vehicle is stopped like a planetary gear type automatic transmission. Sometimes you cannot shift. Therefore, there is a situation that the gear must be shifted to the lowest side as the vehicle speed decreases. That is, when the vehicle speed VSP decreases during coasting, there is a problem that an excessive increase in engine braking force cannot be avoided with the lockup clutch 21 engaged. On the other hand, it is conceivable to release the lock-up clutch 21 at a certain high vehicle speed and suppress the generation of excessive engine braking force, but this is not preferable because the area where the fuel cut control can be applied becomes narrow.

  Therefore, in Example 1, when the vehicle speed V1 at which excessive engine braking is likely to occur is reached, the driving force is applied to the engine by the driving actuator to reduce the engine braking force. If the driving force is applied to the engine, the auxiliary machines and the like are driven together, so that the performance of the air conditioner and the like is not deteriorated. Further, since the high engine speed can be maintained, the fuel cut control region is not narrowed.

  In the first embodiment, the driving force is applied using the inertia member D as the driving actuator. That is, immediately after the start of coasting and if the vehicle speed is high to some extent, the gear ratio is not so low, and excessive engine braking force is not generated. At this timing, the first clutch C1 is released, the second clutch C2 is engaged, and the inertia member D, which is a disk member, is rotated by the inertia energy of the vehicle to store the inertia energy. That is, energy recovery during deceleration is positively performed in a region where there is no sense of incongruity. The second clutch C2 is controlled including slip engagement control to reduce the uncomfortable feeling.

  Next, when the speed ratio becomes low and the engine speed increases to reach the vehicle speed V1 at which the driver begins to feel uncomfortable, the second clutch C2 is released and the first clutch C1 is engaged. At this time, the switching control of the first clutch C1 and the second clutch C2 is also controlled by the slip control so that there is no sense of incongruity. Then, the inertia energy of the inertia member D in the rotating state is transmitted from the first clutch C1 to the engine, that is, a driving force can be given to the engine. The driving force is appropriately adjusted by the engagement control of the first clutch C1 so that the engine braking force becomes constant.

  Next, when the vehicle speed further decreases in this state and the vehicle speed reaches the vehicle speed V2 corresponding to α which is a rotation speed obtained by adding a predetermined amount to the idle rotation speed α1 on the lowest speed ratio, the lockup clutch 21 is reached. To release. That is, if the lock-up clutch 21 is left engaged, the engine speed also falls below the idle speed as the vehicle speed decreases. I can't do it. Therefore, at this time, the lockup clutch 21 is released. At this time, the inertia member D is in a state connected to the engine, and even if the lock-up clutch 21 is released, the drive of the engine by the inertia member D is continued, so that the fuel cut control itself can be continued. In other words, while the inertia member D can release the inertia energy, the engine speed can be controlled to be equal to or higher than the idle speed even if the vehicle is stopped, and the fuel cut control can be continued.

  Next, when the fuel cut control is continued with the lock-up clutch 21 released, the inertia energy stored in the inertia member D is released, and the engine speed decreases when sufficient driving force cannot be applied to the engine. Resulting in. Then, when the engine speed reaches the aisle speed α1, it is determined that further driving is difficult, the first clutch C1 is released, the fuel cut control is turned off, and fuel injection is resumed. Thereby, an engine stall can be avoided.

As described above, the following operational effects can be obtained in the first embodiment.
(1) Engine driving force is input via an engine that performs fuel cut control for stopping fuel supply when coasting and at a predetermined engine speed or higher, and a torque converter that includes a lock-up clutch 21. The belt type continuously variable transmission 20 and a drive actuator (driving means) for applying a driving force to the engine during the fuel cut control are provided. Therefore, the fuel cut control area can be expanded without excessive deceleration.

  (2) The drive actuator applies a driving force so that the deceleration is less than or equal to a predetermined value when the gear ratio of the belt type continuously variable transmission 20 is less than or equal to a predetermined vehicle speed at which the belt ratio is the lowest. Thereby, a stable deceleration can be obtained while expanding the fuel cut control region.

  (3) The drive actuator absorbs energy necessary for the drive actuator to output a driving force at a higher vehicle speed than the predetermined vehicle speed. Specifically, the inertia energy of the vehicle is stored in the inertia member D by the engagement of the second clutch C2. Thereby, a driving force can be applied without newly consuming energy.

  (4) The drive actuator continues the fuel cut control when the gear ratio of the belt type continuously variable transmission 20 reaches the lowest speed and the vehicle speed V2 reaches an engine speed equal to or lower than the idle speed. While releasing the lock-up clutch 21, the engine continues to be driven. Thereby, even if it becomes a vehicle stop state, fuel cut control can be continued.

  Although the first embodiment has been described above, other configurations may be used as long as the objects and effects of the present invention can be obtained. For example, in the first embodiment, the configuration using the inertia member D and the two clutches C1 and C2 as the driving means is shown. However, the configuration may be such that energy absorption by regeneration and energy release by driving are performed by an electric motor or the like. As this electric motor, for example, an existing alternator (generator) may be modified and a driving force may be applied if necessary, a starter motor may be modified, or a separate motor generator may be provided. Thus, regeneration and driving may be performed. In the first embodiment, a single disk-shaped inertia member is used. However, the inertia energy of the vehicle may be stored by combining a plurality of inertia members, or by accumulating hydraulic pressure. The engine may be driven by this hydraulic pressure.

10 Engine 20 Belt type continuously variable transmission 21 Lock-up clutch (lock-up mechanism)
22 Torque converter 80 Vehicle speed sensor 90 Engine rotation sensor
C1 1st clutch (drive means)
C2 Second clutch (drive means)
D Inertia member (drive means)

Claims (4)

An engine that performs fuel cut control to stop fuel supply when coasting and at a predetermined engine speed or higher;
A transmission to which the driving force of the engine is input via a torque converter having a lockup mechanism;
Driving means for applying a driving force to the engine during the fuel cut control;
A vehicle control apparatus comprising: The vehicle control device according to claim 1,
The vehicle control apparatus according to claim 1, wherein the driving means applies a driving force so that the deceleration is not more than a predetermined value when the gear ratio of the transmission is not more than a predetermined vehicle speed at which the gear ratio is the lowest. The vehicle control device according to claim 1 or 2,
The vehicle control apparatus, wherein the driving means absorbs energy on a higher vehicle speed side than the predetermined vehicle speed. The vehicle control device according to any one of claims 1 to 3,
When the gear ratio of the transmission is at the lowest side and the engine speed reaches a vehicle speed that is equal to or lower than the idle speed, the drive means continues the fuel cut control and moves the lockup mechanism A vehicle control device that releases and continues driving of the engine.

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