JP2019214248A - Vehicular control device - Google Patents

Abstract

To provide a vehicular control device capable of improving fuel economy, and avoiding stalling, while suppressing shock at a fuel cut time.SOLUTION: In a vehicular control device in which, when a prescribed condition is satisfied, at a start time of fuel cut for stopping fuel injection of an engine, a clutch on a power transmission path for transferring power from the engine to wheels is subjected to slip control, fuel cut is started after reducing a load of auxiliary machinery driven by the engine.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vehicle control device that stops fuel injection during traveling.

  In Patent Document 1, when the engine starts fuel injection stop control (hereinafter, referred to as fuel cut) during coasting with the accelerator released, the fuel is controlled by slip control of a lock-up clutch. Shock at the start of cut is reduced, and discomfort to the driver is suppressed.

JP-A-5-164241

However, in the technology of Patent Document 1, if the load on the auxiliary equipment of the engine is large, the drop of the engine speed at the time of fuel cut is quickened, and the fuel cut recovery speed at which fuel injection is restarted is easily reduced. However, there has been a problem that the fuel efficiency cannot be sufficiently improved and engine stall occurs.
An object of the present invention is to provide a vehicle control device capable of improving fuel efficiency and avoiding engine stall while suppressing shock during fuel cut.

In order to achieve the above object, according to the present invention, when a predetermined condition is satisfied, at the start of fuel cut for stopping fuel injection of the engine, a clutch of a power transmission path for transmitting power from the engine to wheels is slip-controlled. In the vehicle control device,
The fuel cut is started after reducing the load on the auxiliary device driven by the engine.

  That is, since the fuel cut is started after the load on the auxiliary machine is reduced, the engine speed does not drop excessively, and the fuel efficiency can be improved while avoiding engine stall.

1 is a system diagram of a vehicle to which a vehicle control device according to a first embodiment is applied. 4 is a flowchart illustrating a fuel cut permission / prohibition control process performed in the ECU according to the first embodiment. 5 is a time chart illustrating a fuel cut permission / prohibition control process according to the first embodiment.

DESCRIPTION OF SYMBOLS 1 Engine 3 Automatic transmission 3a Lock-up clutch 3b Forward clutch 4 Compressor 4a Inclined plate control valve 5 Drive wheel 20 Air conditioner controller (ACU)
22 Engine Controller (ECU)
27 Transmission controller (CVTCU)

[Example 1]
FIG. 1 is a system diagram of a vehicle to which the vehicle control device according to the first embodiment is applied. The rotation output from the engine 1, which is an internal combustion engine, is input to the automatic transmission 3. The rotation input to the automatic transmission 3 is input to the forward / reverse switching mechanism 32 via the torque converter 31 and the lock-up clutch 3a, and is input to the belt-type continuously variable transmission mechanism 33 from the forward clutch 3b of the forward / reverse switching mechanism 32. You. The lock-up clutch 3a controls the transmission torque capacity based on a control oil pressure supplied from a control valve (not shown). The rotation shifted by the belt-type continuously variable transmission mechanism 33 is transmitted to the drive wheels 5 via the final gear. The engine 1 has a throttle valve 1a for adjusting an intake air amount and an injector 1b for controlling a fuel injection amount.

  The engine 1 has a variable displacement compressor 4 of a vehicle air conditioner (hereinafter also referred to as an air conditioner) as an auxiliary device. The compressor 4 is of a tilted plate piston type, and drives a piston by rotating a tilted plate (not shown) attached at an angle to the rotation axis to compress the refrigerant. The compressor 4 has a tilt plate control valve 4a, and changes the stroke of the piston by changing the tilt of the tilt plate. Thereby, the refrigerant discharge capacity of the compressor 4 is controlled. The compressor 4 is driven by the engine 1 via a pulley and a belt. As the compressor 4 of the first embodiment, an inclined plate piston type is exemplified, but any other type may be used as long as it is a variable displacement type compressor capable of controlling the refrigerant discharge capacity. The load of the compressor 4 is large when the refrigerant discharge capacity is large, and is small when the refrigerant discharge capacity is small. In the first embodiment, the compressor 4 is illustrated as a specific example of the accessory, but another accessory such as an alternator or a power steering pump may be provided.

  The engine control unit 22 (hereinafter, referred to as ECU) calculates a target engine torque based on a required torque according to the accelerator pedal opening. The engine speed sensor 23 detects the engine speed Ne and outputs it to the ECU. The vehicle speed sensor 24 detects the vehicle speed VSP and outputs it to the ECU. The accelerator opening sensor APO detects the accelerator pedal opening of the driver and outputs the detected result to the ECU. The ECU controls the operating state of the engine 1 (engine speed Ne and engine torque Te) by controlling the throttle valve 1a and the injector 1b of the engine 1. When a predetermined condition is satisfied, the ECU performs a fuel cut for stopping the fuel injection (details will be described later).

  The transmission control unit 27 (hereinafter, referred to as CVTCU) receives a range position signal transmitted from a shift range (not shown), and determines whether or not the lock-up clutch 3a is connected or disconnected, and whether or not the belt-type continuously variable transmission mechanism 33 is in operation. Control the gear ratio. The air conditioner control unit 20, the ECU, and the CVTCU are connected by a CAN communication line capable of transmitting and receiving mutual information.

  The air conditioner control unit 20 (hereinafter, referred to as ACU) is a control device that controls air conditioning in the vehicle compartment. The ACU receives the pressure signal detected by the pressure sensor 10 and the temperature signal detected by the temperature sensor, and exchanges various signals with the ECU and the CVTCU (such as a discharge capacity command value of the compressor 4 and a pressure signal). Etc.). Further, in the ACU, the inclined plate control valve 4a of the compressor 4 is controlled so as to reach the set vehicle interior temperature set by the occupant or the like.

(Fuel cut control processing)
Fuel cut (hereinafter also referred to as FC) for stopping fuel injection of the engine 1 determines whether the lock-up clutch 3a is in a lock-up state (also described as ON) and determines whether the accelerator pedal opening APO is zero. It is determined whether or not the vehicle speed VSP is equal to or higher than a predetermined vehicle speed at which FC is permitted. When the lockup is ON, APO = 0, and VSP is equal to or lower than the predetermined vehicle speed, FC is executed (also described as ON). . At the start of FC, slip control of the forward clutch 3b is performed in order to suppress fluctuations in deceleration. The slip control is control for feeding back the engagement pressure so that the slip amount of the forward clutch 3b becomes a predetermined amount set in advance. Specifically, the engagement pressure is controlled to a torque capacity slightly lower than the torque acting before and after the forward clutch 3b, and the forward clutch 3b is slightly slipped. As a result, even if the torque on the engine side suddenly changes, a sudden change in the acceleration acting on the vehicle (hereinafter, referred to as a vehicle G) is suppressed.

(About compressor displacement control at the start of fuel cut control)
The ECU performs a fuel cut during deceleration of the vehicle to improve fuel efficiency. At this time, the engine stall is prevented by controlling the slip of the forward clutch 3b and suppressing the decrease in the engine speed Ne while suppressing the excessive torque fluctuation. In the state where the fuel cut is being performed, the friction for the engine 1 and the power for rotating the alternator (not shown) act in a direction to decelerate the vehicle via the forward clutch 3b. Here, for example, when FC is started in a state where the compressor 4 which is one of the auxiliary machines is on, when the load of the compressor 4 which is an auxiliary machine is applied in addition to the normal engine friction, the slip control is performed on the engine side. An excessive load equal to or higher than the set predetermined torque may occur, and the engine speed Ne may decrease rapidly. Then, the engine rotation speed Ne drops to the recovery rotation speed Ner at which the FC is terminated, and the FC must be terminated immediately, so that the fuel efficiency cannot be sufficiently improved. In some cases, the engine may stall. Therefore, in the first embodiment, when starting the FC, the load on the auxiliary equipment is reduced before starting the FC, and then the slip control is performed to start the FC.

(Fuel cut permission / prohibition control processing)
FIG. 2 is a flowchart illustrating a fuel cut permission / prohibition control process performed in the ECU according to the first embodiment.
In step S1, it is determined whether or not there is an FC request. When there is a request, the process proceeds to step S2, and otherwise, the control flow ends.
In step S2, it is determined whether there is a slip control request for the forward clutch 3b. If there is a slip control request, the process proceeds to step S3; otherwise, the control flow ends. If the forward clutch 3b does not need to perform the slip control, there is no possibility that the engine speed Ne excessively decreases.

In step S3, it is determined whether or not the compressor 4 is on. If it is on, the process proceeds to step S6, and if it is off, the process proceeds to step S4.
In step S4, since the compressor 4 is turned off, it is determined that the load on the auxiliary equipment is small and there is no possibility that the engine speed Ne is excessively reduced, and the slip control is started.
In step S5, FC is permitted after the start of the slip control.

  On the other hand, in step S6, it is determined whether or not the load reduction control may be permitted when the compressor 4 is on. If it is permitted, the process proceeds to step S8. If not, the process proceeds to step S7. Prohibit FC. Here, the load reduction control is control for reducing the capacity of the compressor 4 which is an auxiliary machine and reducing the compressor driving load. If the driver wants to operate the air conditioner and the capacity of the compressor 4 cannot be reduced, such as when the difference between the set vehicle interior temperature and the actual vehicle interior temperature is large, the load reduction control cannot be permitted. Therefore, FC is prohibited. On the other hand, when the driver does not want to operate the air conditioner, or when the difference between the set vehicle interior temperature and the actual vehicle interior temperature is small, even if the capacity of the compressor 4 is reduced, the vehicle interior environment is adversely affected. If not, the load reduction control is permitted.

In step S8, load reduction control is performed. Specifically, the capacity of the compressor 4 is reduced, and control is performed such that the driving load of the compressor 4 becomes equal to or less than a predetermined value.
In step S9, it is determined whether or not the compressor drive load has become equal to or less than a predetermined value. If the load is equal to or less than the predetermined value, the flow proceeds to step S4 to start slip control and permit FC. On the other hand, if the compressor driving load is larger than the predetermined value, the process returns to step S8, and the compressor driving load is reduced.

FIG. 3 is a time chart illustrating a fuel cut permission / prohibition control process according to the first embodiment. This time chart shows a coast running state in which the lock-up clutch 3a is locked up, the forward clutch 3b is in a fully engaged state, and the compressor 4 is driven with a drive load equal to or more than a predetermined value.
At time t1, the FC start condition is satisfied, and the FC request is output. Here, a comparative example in which FC is started without reducing the capacity of the compressor 4 will be described. In the case of the comparative example, since the FC is started at the time t1, the engine torque Te (ratio) of the comparative example starts to decrease and the slip control of the forward clutch 3b is performed as shown by the dashed line in the column of Te in FIG. Starting, the engagement pressure of the forward clutch 3b is reduced. The one-dot chain line in the column of the forward clutch pressure in FIG. 3 indicates the target clutch pressure P * (ratio), and the two-dot chain line indicates the actual clutch pressure P (ratio). Then, as indicated by the one-dot chain line in the rotation speed column in FIG. 3, since the driving load of the compressor 4 is large, the actual engine rotation speed Ne (ratio) decreases at a stretch toward the recovery rotation speed Ner. Then, the fuel injection is immediately restarted, so that the fuel efficiency cannot be sufficiently improved. On the other hand, in the embodiment, since the load reduction control for reducing the capacity of the compressor 4 is first started, the start of FC is delayed, but it is possible to avoid a situation in which the fuel injection is immediately restarted.

  At time t2, when the capacity of the compressor 4 becomes equal to or less than a predetermined value, the slip control is started. As a result, as shown by the solid line in the forward clutch pressure column, the target clutch pressure P * (actual) is reduced, and accordingly, the actual clutch pressure P (actual) starts to decrease. Although the engine torque Te (actual) also decreases because the driving load is reduced due to the decrease in the compressor capacity, the engine torque Te (actual) is a positive torque because fuel is still being injected. However, the transmission capacity of the forward clutch 3b decreases due to the decrease in the forward clutch pressure, and the engine speed Ne (actual) of the embodiment in the rotational speed column is slightly lower than the primary rotational speed Npri (actual). Converge to the vicinity.

  At time t3, when it is confirmed by the slip control that a predetermined amount of slip has occurred in the forward clutch 3b, an FC permission signal is output, and fuel injection is stopped. At this time, a sudden change of the vehicle G is suppressed by the slip control, and an excessive decrease in the engine speed Ne is suppressed while absorbing a shock at the start of FC. Then, the engagement pressure of the forward clutch 3b is gradually shifted to the fully engaged state, and a decrease in the engine speed Ne is suppressed.

  At time t4, when the engagement pressure of the forward clutch 3b shifts to the fully engaged state, the reduced compressor capacity is increased toward the capacity before the start of the load reduction control. As a result, it is possible to prevent a sudden decrease in the engine speed Ne while avoiding a shock at the start of FC, and thereafter, by returning the reduced compressor capacity, it is possible to maintain a normal running state.

As described above, the first embodiment has the following functions and effects.
(1) When a predetermined condition is satisfied, a vehicle control device that performs slip control of a clutch in a power transmission path that transmits power from the engine 1 to wheels at the start of fuel cut for stopping fuel injection of the engine 1 includes:
Fuel cut is started after the load on the compressor 4 (auxiliary machine) driven by the engine 1 is reduced.
That is, since the fuel cut is started after the load on the compressor 4 is reduced, the engine speed does not drop excessively, and the fuel efficiency can be improved while avoiding engine stall.

  (2) The clutch is a forward clutch 3b (forward clutch) of the transmission provided on the power transmission path. Therefore, the torque capacity can be finely controlled, and the shock at the start of FC can be further reduced.

  (3) When the load of the compressor 4 is larger than a predetermined value set in advance, the fuel cut is started after the load of the compressor 4 is reduced to a predetermined value or less. Therefore, the driving load of the compressor 4 can be reliably reduced to a value at which the engine speed Ne does not excessively decrease, and fuel efficiency can be improved while stably avoiding engine stall.

  (4) When it is determined that the load on the compressor 4 cannot be reduced by an operation request to the compressor 4, the fuel cut and slip control are prohibited. Thus, engine stalls and shocks can be avoided while satisfying the operation requirements for the compressor 4.

[Other Examples]
Although the present invention has been described based on the embodiments, the specific configuration may be another configuration. In the first embodiment, the example in which the belt-type continuously variable transmission mechanism 3b is adopted as the transmission is shown. However, another type of transmission may be used. In the first embodiment, the slip control is performed by the forward clutch 3b. However, the lock-up clutch 3a of the torque converter 31 provided on the power transmission path may be used. Thereby, the durability of the forward clutch 3b can be improved as compared with the case where the forward clutch 3b is used.

Claims (5)

When the predetermined condition is satisfied, at the start of fuel cut to stop fuel injection of the engine, in the vehicle control device for slip control of a clutch of a power transmission path that transmits power from the engine to wheels,
The vehicle control device according to claim 1, wherein the fuel cut is started after reducing a load on an auxiliary device driven by the engine. The control device for a vehicle according to claim 1,
The vehicle control device according to claim 1, wherein the clutch is a lock-up clutch of a torque converter provided on the power transmission path. The vehicle control device according to claim 1 or 2,
The vehicle control device according to claim 1, wherein the clutch is a forward clutch of a transmission provided on the power transmission path. The vehicle control device according to any one of claims 1 to 3,
When the load on the auxiliary machine is larger than a predetermined value set in advance, the fuel cut is started after the load is reduced to the threshold value or less. The vehicle control device according to any one of claims 1 to 4,
A control device for a vehicle, wherein when it is determined that the load on the auxiliary device cannot be reduced according to an operation request for the auxiliary device, fuel cut and the slip control are prohibited.

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