JP2566233B2 - Engine fuel control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fuel control device for an engine.

(Prior Art) In recent years, many automobile engines have a so-called deceleration fuel cut control device that stops fuel supply when the vehicle is in a deceleration state from the viewpoint of improving fuel efficiency and protecting the catalyst ( See, for example, JP-A-59-162348). In order to maximize fuel efficiency performance in an engine having such a deceleration fuel cut function, it is desirable to exhibit the deceleration fuel cut function in the widest engine speed range. For this reason, in particular, an engine or the like designed with an emphasis on fuel efficiency is configured so that the deceleration fuel cut control can be performed in all rotation regions from a high speed region to a low speed region.

(Problems to be Solved by the Invention) However, when the deceleration fuel cut is performed over the entire region from the high speed region to the low speed region as in the above-described conventional technique, the following problems occur. That is, in general, the engine speed is low in the low speed range and the running inertia of the vehicle is also low. Therefore, the rotational state of the engine is more likely to be unstable than in the high speed range.

Especially, when the vehicle is cornering when the brake is further depressed due to entering the low speed range, the normal clutch is further disengaged when the engine speed greatly decreases and the running inertia becomes small. It will not work at all. Nevertheless, if the fuel cut is still continued in such a state, engine stall may occur. Particularly in recent years, in order to reduce the steering force of the steering, many vehicles are equipped with a power steering device that power assists the steering force of the steering by the pressure of a hydraulic pump driven by an engine. Acts as a significant engine load.

Since the power steering device always operates during cornering of the vehicle, the engine stall is particularly likely to occur in a vehicle equipped with such a power steering device.

(Means for Solving Problems) The present invention has been made for the purpose of solving the above problems, and is provided with a deceleration fuel cut control device for stopping the supply of fuel to the engine when the vehicle is decelerated. On the other hand, in an engine equipped with a power steering device for reducing the steering force of the steering wheel, a clutch connection state detecting means for detecting a clutch connection state and a power steering operation state detection for detecting an operation state of the power steering device. Means for controlling the fuel cut control of the fuel cut control device when the power steering device is in the operating state by the means, the power steering operation state detection means and the clutch connection state detection means and the clutch is disengaged. A cut control suppressing means is provided.

(Operation) According to the above means, the fuel cut operation is released when the engine stall with the clutch disengaged is likely to occur during operation of the power steering device such as during cornering of the vehicle. Even if the engine speed is greatly reduced due to clutch disconnection during the course of driving, etc. and the running inertia is also reduced, sufficient engine output can be guaranteed, and the engine will operate even if the power steering device with a large engine load operates. No more stalls.

(Embodiment) First, FIGS. 2 to 3 show a fuel control device for an automobile engine according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a control system of the same embodiment device, FIG. 3 is a cross-sectional view of the engine carburetor part in the apparatus of the same embodiment, and FIG. 4 is a flow chart for explaining the control operation of the apparatus of the same embodiment.

First, a schematic diagram of the control system of the embodiment of the present invention will be described with reference to FIG. 2, and then control of main parts will be described.

In FIG. 2, reference numeral 1 is an engine body, intake air is sucked in from the outside through an air cleaner 30, and then a fixed venturi type carburetor downstream of the air cleaner 30.
At 14, it is mixed with fuel and supplied to each cylinder. The amount of the air-fuel mixture sucked into the cylinder is controlled by the throttle valve 22 provided in the throttle chamber of the carburetor 14.
Controlled by. The throttle valve 22 is operated in conjunction with the accelerator pedal, and is maintained at the minimum opening state during idling and during deceleration operation. This throttle valve 22 is provided with an idle switch SW _ID coaxially,
The idle switch SW _ID is turned on and an ON signal is output during the above idle and deceleration operation. As shown in FIG. 3, the carburetor 14 includes a float chamber 24 that communicates with a main nozzle 21 disposed upstream of a throttle valve 22 in the intake passage 20 and a fuel tank 12 via a fuel pump 13. And a main fuel passage 26 for communicating the float chamber 24 with the main nozzle 21, and a slow port for slow fuel supply branched from the main fuel passage 26.
23 and a slow fuel passage 27 communicating with an idle port 31 arranged on the downstream side of the throttle valve 22. The idle port 31 is provided with an idle nozzle 32 whose tip projects into the intake passage 20 and an idle adjust screw 28 for adjusting the opening area of the idle nozzle 32 on the base end side. Further, a slow cut solenoid valve 17 is attached to an intermediate position of the slow fuel passage 27, and when the engine is decelerated, the slow cut solenoid valve 17 closes the slow fuel passage 27 to supply slow fuel. It is configured to shut off. That is, the deceleration operation detecting means detects that the engine has been decelerated, and the slow cut solenoid valve 17 is operated by the engine control unit 9 described later based on the signal (Fc) from the detecting means. Has been done. Reference numeral 25 is a slow intake passage.

On the other hand, reference numeral 13 in FIG. 2 denotes an exhaust manifold attached to the cylinder head portion of the engine body 1,
An exhaust pipe 10 is connected to the exhaust manifold 13. Further, a three-way catalytic converter 11 is installed midway in the exhaust system passage of the exhaust pipe 10.

By the way, a power steering device is attached to the steering of the automobile in the present embodiment. This power steering system includes a hydraulic pump driven by the engine, and opens and closes flapper valves of a pair of antiphase boosting cylinders in response to steering turning in the left-right direction to apply the hydraulic pressure of the hydraulic pump to its piston. It is designed to operate and power assist steering operation. The power steering device is provided with a power steering switch SWps which is turned on in response to an increase in hydraulic pressure due to opening of the flapper valve. Then, the operation set value is set corresponding to the steering angle during steering of the vehicle. In addition, the above steering,
A steering angle sensor for detecting the steering angle θ of the steering is provided.

Further, reference numeral 9 is an engine control unit (hereinafter referred to as ECU), which is mainly composed of, for example, a microprocessor (CPU) and has a memory (ROM and RA).
M) and interface (I / O) circuits. Then, in the interface circuit of the ECU 9, for example, a cooling water temperature detection signal Tw of the engine body 1 detected by the water temperature detection thermistor 16, an engine boost pressure detection signal B detected by the boost pressure sensor 35, and an RPM sensor 15 are provided. Various data signals necessary for controlling the basic performance of the engine, such as the engine speed detection signal N detected by, are input.

As will be described later in detail, the ECU 9 drives the slow cut solenoid valve 17 of the carburetor 14 to close the slow fuel passages 25 and 27 and cut the supply of slow fuel when the engine is in the decelerating operation state. In addition to the slow cut (deceleration fuel cut) control function, the operation of the slow cut control function is prohibited when the vehicle in which the power steering device is operated and the steering wheel is operated by a predetermined rotation angle or more is in the cornering state. In addition to the basic data signal described above, the ECU 9 is provided with a slow cut prohibition control function for controlling the gear cut-in switch SW _G , brake switch SW _B , power steering switch SWps, Various running status detection signals such as each ON signal of the clutch switch SWc, steering steering angle detection signal θ of the steering angle sensor, etc. It is adapted to be input also together.

Next, the engine control unit (ECU) 9
The slow cut (slow fuel cut) control and the prohibiting operation thereof will be described in detail with reference to the flowchart of FIG.

That is, first, in step S ₁ , it is determined whether or not the value of the engine cooling water temperature Tw input to the ECU 9 is equal to or higher than a predetermined reference temperature T ₁ (70 ° C.) indicating the completion of warming up of the engine, that is, the current engine. It is determined whether or not the operating state is the warm-up completion state, and if YES is the warm-up completion state, further step S ₂
Next, while determining whether the idle switch SW _ID indicating the open / closed state of the throttle valve 22 is ON or OFF, if NO (cold state), the engine returns immediately and the engine warm-up is completed. Repeat the above operation until you do.

ON / O of idle switch SW _ID in this step S ₂
The determination of FF is to determine the open / closed state (whether fully closed) of the throttle valve 22 as a deceleration state determination condition of the engine during steady running as described above, and when the idle switch SW _ID is ON (YES ) Indicates that the throttle valve 22 is fully closed and the vehicle is decelerated with the foot released from the accelerator pedal, while when OFF (NO), the accelerator pedal is depressed and the throttle valve 6 is opened to the predetermined position. Indicates that the vehicle is in a non-deceleration state that is opened more than once.

When the idle switch SW _ID is ON (YES)
The next proceeds to step S ₃ at the time of current engine speed N is traveling straight ahead which is detected by the RPM sensor 15, when multiplied by the engine brake foot off the accelerator pedal (the deceleration state in which no step on the brake ) Is lower than a predetermined reference speed (minimum speed) N ₁ (N ₁ = 1900 rpm) for performing a slow cut (deceleration slow fuel cut). It is determined whether the engine speed has decreased to the region where the fuel should be returned (see FIG. 5).

As a result, in the case of NO (N> N ₁ ), the engine speed N is in the slow cut rotation region (see FIG. 5) beyond the slow fuel return region due to completion of warm-up, and the throttle valve is fully closed. immediately step S without performing adequately determine various parameters for the slow cut release of the following steps S ₄ to S ₁₀ admitted that it is possible to throw cut since it is
Moving to ₁₂ , the slow cut control corresponding to the deceleration state is performed.

On the other hand, in the case of YES (N <N ₁ ) in which the actual engine speed N is lower than the reference speed N ₁ for performing the slow cut during the straight-line deceleration traveling (N <N ₁ ), steps S ₄ and S ₅ are further performed.
Then, the ON state or OFF state of each of the gear-in switch SW _G and the clutch switch SWc described above is sequentially determined. As a result, the gear-in state (SW
_G ON: YES) and the clutch is disengaged (SWcON: YES), the process proceeds to the next step S ₆ and the actual engine speed N at that time is the idling speed (Fig. 5). whether a second larger than the reference rotational speed N ₂ corresponding to 900 rpm), i.e. whether the current engine operating region is in the slow fuel return rotation in the region to release the slow-cut shown in the large 5 Figure To judge.

As a result, in the case of YES, the closed state of the electric load in yet step S ₇ on predicted to be prima facie require release of the slow cut (ON or OFF), and in step S ₈ of the throttle valve 22 In addition to the fully closed state, the brake switch SW _B is turned on or off to show a concretely larger deceleration state, which is premised on cornering, and the operation of the power steering device is also premised on cornering determination in step S _9. ON of power steering switch SWps, which indicates the status
Or judge the OFF state respectively. As a result, each Y
Reference steering angle advances further step S ₁₀ in the case of ES steering of the steering angle θ corresponds to the cornering state θ
It is finally judged whether or not it is ₁ or more. As a result, in the case of YES, the current engine operating state is a large deceleration state, which is different from the deceleration due to the engine brake when the vehicle is traveling straight ahead, with the throttle valve 22 fully closed and the brakes being depressed. In addition, since the steering is turned at a steering angle equal to or greater than a predetermined value, and as a result, the power steering device is operating at a hydraulic pressure equal to or greater than a predetermined value, that is, the vehicle is clearly cornering. In order to prevent engine stalling, the process proceeds to the next step S _11, and the slow cut control in step S ₁₂ is canceled. This reliably prevents engine stall when the clutch is disengaged when the power steering device is loaded on the engine by the cornering of the vehicle in the low rotation region corresponding to the slow cut return rotation region of FIG. Will be able to do it.

On the other hand, in each case NO in step S ₄ to S ₉ is returned to all directly Step S ₁ not needed to perform the releasing of the slow cut.

If NO in steps S ₉ and S ₁₀ , it is determined that the vehicle is not in the cornering state, and the process proceeds to step S ₁₂ described above to continue the slow cut control.

In the above embodiment, in addition to the conditions of fully closing the throttle valve 22, disconnecting the clutch, stepping on the brake, turning on the power steering switch SWps, the steering angle of the steering wheel corresponds to the cornering detection in the above embodiment. The power steering switch SWps is designed to operate more strictly under the condition that the steering wheel is operated at an angle θ ₁ or more. However, the power steering switch SWps originally has a predetermined steering angle θ ₁ corresponding to the cornering.
Since it is made ON when the steering has been described above, the condition (step S ₁₀₎ It is also possible to omit course in some cases.

(Effects of the Invention) As described above, the present invention includes the deceleration fuel cut control device so as to stop the fuel supply to the engine when the vehicle decelerates, while reducing the steering force of the steering. In an engine equipped with a steering device, a clutch connection state detection means for detecting a clutch connection state, a power steering operation state detection means for detecting an operation state of the power steering device, a power steering operation state detection means and a clutch connection. And a fuel cut control suppressing means for suppressing the fuel cut control of the fuel cut control device when the disengagement of the clutch is detected by the state detecting means and the power steering device is in the operating state. It is a thing.

Therefore, according to the present invention, when the power steering device is operating, such as when the vehicle is cornering, the fuel cut operation is released when the engine stall with the clutch disengaged is likely to occur. The engine output can be guaranteed even when the engine speed is greatly reduced due to the clutch cut and the driving inertia is also reduced, and the engine stalls even if the power steering device with a large engine load operates. There is nothing to do.

In addition, when the cornering state of the vehicle is detected, that is, because the fuel supply is started immediately at the beginning of cornering, the fuel will be restored before the engine speed decreases relatively. It will be possible to simultaneously prevent torque shock and engine stall due to misfire.

Particularly in the carburetor engine as disclosed in the above-described embodiment, the fuel supplied to the engine combustion chamber is sucked along the wall surface of the intake passage, and the liquid level of the fuel in the float chamber greatly changes during cornering. Therefore, there are circumstances in which a stable fuel supply cannot be achieved.

For this reason, if the fuel is restored during cornering, engine stall is more likely to occur, but if the slow cut is released early at the start of cornering as described above, it is also effective as a countermeasure in such cases. Will be things.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to the claims of the present invention, FIG. 2 is a control system diagram of an engine fuel control device according to an embodiment of the present invention, FIG. 3 is a sectional view of a carburetor in the system, and FIG. FIG. 5 is a flow chart showing the control operation of the engine control unit in the system, and FIG. 5 is an explanatory diagram showing the control area during fuel control in the system. 1 …… Engine body 2 …… Air flow meter 9 …… Engine control unit (ECU) 10 …… Exhaust pipe 12 …… Fuel tank 14 …… Vaporizer 15 …… RPM sensor 16 …… Water temperature thermistor 17 …… Slow cut solenoid Valve 20 ... Boost pressure sensor

Claims (1)

(57) [Claims] 1. An engine equipped with a deceleration fuel cut control device for stopping fuel supply to the engine when the vehicle decelerates, and an engine equipped with a power steering device for reducing steering force of a steering wheel, in which an engagement of a clutch is provided. Clutch connection state detection means for detecting the state, power steering operation state detection means for detecting the operation state of the power steering device, and the power steering device is operated by the power steering operation state detection means and the clutch connection state detection means. In a state, a fuel cut control suppressing means for suppressing the fuel cut control of the fuel cut control device when the clutch disengagement is detected is provided, and the engine fuel control device.