JP2003227372A - Control device for engine of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain function of traction control for reducing an engine output by a driver according to the driving state as soon as possible after engine starting with simple constitution and without making a system complicated or large-scaled. <P>SOLUTION: The time after engine starting when the air-fuel ratio control is possible by activating O2 sensor 34 to the engine water temperature upon engine starting at the step S101 is read in. At the following step S102, if the time up to present after starting of the engine is beyond the time after starting of S101 by comparing the time after starting from a map with the time up to present, it is judged that the air-fuel control of an engine is possible, allowing advance to the step S103 and the control of the engine output by the traction control is permitted. If the time up to present after starting of the engine does not reach the time after starting of S101 as the result of the judgment of S102, allowing to advance to the step S104 and the control of the engine output by traction control is prohibited. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle having a traction control device for reducing an engine output to maintain a predetermined vehicle behavior, and in particular, a vehicle for accurately determining whether or not traction control can be executed at engine start. Engine control device.

[0002]

2. Description of the Related Art Generally, a vehicle engine control device prohibits traction control such as torque reduction of engine output when it is judged that engine combustion is not stable when the engine water temperature is low. The driver cannot enjoy the traction control function until the engine water temperature rises.

For example, in Japanese Unexamined Patent Publication No. 11-157366, at least the fuel cut control and the cylinder cut control are prohibited and the torque down control is suppressed when the engine is cold, so that the load on the engine increases as the engine output decreases. There is disclosed a technique of suppressing the above, while increasing the control ratio of the braking control such as ABS control.

[0004]

However, in the above-mentioned prior art, an automatic braking system is indispensable for the vehicle, and the entire system becomes large-scaled.
There is a problem that complicated cooperative control with an automatic braking system must be performed.

The present invention has been made in view of the above circumstances.
Even in a vehicle without an automatic braking system,
In addition, the engine of a vehicle is a simple structure without making the system large and complicated, and the driver can enjoy the function of traction control that reduces the engine output according to the driving state in the shortest possible time after the engine is started. An object is to provide a control device.

[0006]

In order to achieve the above object, an engine control device for a vehicle according to claim 1 of the present invention is a traction control that keeps a predetermined vehicle behavior by reducing at least an engine output according to a driving state. Have means,
In an engine control device for a vehicle that executes air-fuel ratio control based on a signal from an air-fuel ratio sensor provided in an exhaust system, air-fuel ratio control execution determination means that determines whether the air-fuel ratio control of the engine is feasible, and the air-fuel ratio control And a traction control permission means for permitting control of the engine output by the traction control when the execution determination means determines that the air-fuel ratio control of the engine can be performed.

According to a second aspect of the present invention, there is provided an engine control device for a vehicle according to the first aspect, wherein the air-fuel ratio control execution determining means has the engine water temperature at the engine start time and the engine start time. It is characterized in that it is determined whether or not the air-fuel ratio control of the engine can be executed in accordance with the elapsed time after that.

That is, an engine control apparatus for a vehicle according to a first aspect of the present invention has a traction control means for keeping at least a predetermined vehicle behavior by reducing an engine output in accordance with a driving state, and an air-fuel ratio sensor provided in an exhaust system. In the vehicle engine control device that executes the air-fuel ratio control based on the signal of, the air-fuel ratio control execution determination means determines whether the air-fuel ratio control of the engine can be executed, and the traction control permission means determines the air-fuel ratio control execution determination means. When it is determined that the air-fuel ratio control of the engine can be executed, the control of the engine output by the traction control is permitted. Generally, in the engine control, when the air-fuel ratio control cannot be performed, the fuel and the ignition timing are adjusted by the open loop control to maintain the engine speed, so that the control becomes a certain type and the transition is transient. It is set so that it cannot follow the movement. In such a state, if the traction control operates and the torque of the engine output is reduced, the control may not be optimally performed. However, in the state where the air-fuel ratio can be controlled even if the engine water temperature is low, the fuel feedback control can be performed according to the output of the air-fuel ratio sensor, so even if the torque reduction of the engine output by the traction control is instructed, the feedback control is sufficiently performed. Is possible. Therefore, it is determined whether the air-fuel ratio control of the engine is feasible, and if it is determined that the air-fuel ratio control of the engine is feasible, the engine output is controlled by the traction control to allow the driver to output the engine output according to the operating state. It is possible to enjoy the reduced traction control function in the shortest possible time after the engine is started.

More specifically, as in the engine control device for a vehicle according to claim 2, the air-fuel ratio control execution determining means determines the engine water temperature at the engine start and the elapsed time after the engine is started. Accordingly, it is determined whether the air-fuel ratio control of the engine can be executed. That is, the time until the air-fuel ratio sensor is activated is known from the engine water temperature when the engine is started, and the time until the air-fuel ratio control becomes possible is known.Therefore, this time and the elapsed time since the engine was started By comparing with, it is determined whether the air-fuel ratio control of the engine is feasible.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 relate to an embodiment of the present invention, FIG. 1 is a schematic configuration diagram relating to a vehicle drive system, a traction control device, and an engine control device, and FIG. 2 is a schematic configuration explanatory diagram of an electronic control throttle valve, FIG. FIG. 4 is a functional block diagram of traction control in the engine control device, FIG. 4 is a characteristic explanatory diagram of a starting water temperature and a post-start time when traction control is possible, and FIG. 5 is a flowchart of traction control permission determination in the engine control device.

In FIG. 1, reference numeral 1 indicates an engine,
The engine 1 is connected to a center differential device 4 via a clutch 2 and a transmission 3. The center differential device 4 is composed of, for example, a complex planetary gear type center differential device, and distributes the torque distribution between the front and rear shafts to equal torque or unequal torque such as rear wheel bias depending on the specifications of the gears.

The driving force distributed from the center differential device 4 to the rear wheel side is input to the rear final drive device 8 via the rear drive shaft 5, the propeller shaft 6 and the drive pinion 7.

On the other hand, the driving force distributed from the center differential device 4 to the front wheels is input to the front differential device 12 via the transfer drive gear 9, the transfer driven gear 10, and the front drive shaft 11.

The driving force input to the rear final drive unit 8 is applied to the left rear wheel 1 via the rear wheel left drive shaft 13rl.
4 rl, right rear wheel 14rr via rear wheel right drive shaft 13rr
Front differential device 12 while being transmitted to
The driving force input to is transmitted to the left front wheel 14fl via the front wheel left drive shaft 13fl and to the right front wheel 14fr via the front wheel right drive shaft 13fr.

Further, in FIG. 1, reference numeral 20 indicates a four-wheel brake pressure control device provided with a pressure source, a pressure reducing valve, a pressure increasing valve, and the like,
A master cylinder 22 that is interlocked with a brake pedal 21 is connected to the four-wheel brake pressure control device 20.

The four-wheel brake pressure control device 20 is connected to the four-wheel 1 via brake lines 23rl, 23rr, 23fl and 23fr.
Wheel cylinder 24 of 4rl, 14rr, 14fl, 14fr
rl, 24rr, 24fl, and 24fr are separately piped.

When the driver depresses the brake pedal 21, the brake pressure generated in the master cylinder 22 is introduced into the wheel cylinders 24rl, 24rr, 24fl, 24fr to apply the brake. When a brake signal is input from a traction control device 40, which will be described later, the pressure reducing valve and the pressure increasing valve are opened and closed to introduce the hydraulic pressure of the pressure source to the wheel cylinders 24rl, 24rr, 24fl, 24fr, and the four wheels 14r.
The brake pressures of l, 14rr, 14fl and 14fr can be automatically increased, maintained or reduced.

The vehicle is equipped with a traction control device 40 as a traction control means for maintaining a predetermined vehicle behavior by applying a braking force and reducing the engine output in accordance with the driving state of the vehicle. The control device 40 includes wheel speed sensors 31rl, 31rr, 31fl, 3 that detect the wheel speeds of the four wheels 14rl, 14rr, 14fl, 14fr.
A longitudinal acceleration sensor 32 that detects longitudinal acceleration of the vehicle is connected to 1fr.

The traction control device 40 executes, for example, the traction control proposed by the present applicant in Japanese Unexamined Patent Publication No. 8-207607. Specifically, the actual slip ratios of the four wheels are calculated from the signals of the wheel speeds of the four wheels, and the target slip ratios of the front and rear wheels are determined according to the traveling state by map search or the like, and the slip ratios of the four wheels are calculated. If even one exceeds the target slip ratio, the traction control operation is judged. Then, when the traction control is activated, the target brake pressures of the four wheels are separately calculated based on the deviation between the slip ratios of the four wheels and the target slip ratios of the front and rear wheels, and the command signals of these target brake pressures are sent to the four-wheel brake pressure control device 20. Output to. When the traction control is activated, the target slip amount and the actual slip amount are compared for the fastest rotating wheel, the engine target torque is determined by the engine output reduced by the difference between the two, and this engine target torque is used for traction control. Is output to the engine control device 50 together with the signal.

The engine control unit 50 includes a water temperature sensor 33 for detecting the engine water temperature, an O2 sensor 34 as an air-fuel ratio sensor provided upstream of the exhaust system catalyst for detecting the oxygen concentration in the exhaust gas, and others not shown. Sensors and switches such as a crank angle sensor, an air flow sensor, a throttle sensor, an accelerator sensor, and an air conditioner switch are connected. Further, because of the three-way catalyst purification function, the air-fuel ratio feedback control for constantly performing feedback control by the output from the O2 sensor 34 so as to be close to the stoichiometric air-fuel ratio, ignition timing control, and other electronic devices installed in the intake system of the engine 1 Known control necessary for the engine 1 such as throttle valve control for controlling the throttle opening of the control throttle valve 25 is executed. Further, the engine control device 50 determines whether the air-fuel ratio control of the engine 1 can be executed according to the engine water temperature from the water temperature sensor 33 and the elapsed time after the engine 1 is started, and the engine air-fuel ratio control is executed. When it is determined that it is possible, control of engine output by traction control is permitted.

As shown in FIG. 2, the electronically controlled throttle valve 25 provided in the throttle body of the engine 1 is connected to a throttle motor 26 such as a DC motor via a gear mechanism 27. The throttle motor 26 is driven by a throttle valve control unit 52 of the engine control device 50, which will be described later.

Next, the traction control function of the engine control unit 50 will be described in detail with reference to the functional block diagram of FIG. That is, the engine control device 50 determines the traction control permission determining unit 51 regarding the traction control function.
And a throttle valve control unit 52.

The engine water temperature is input from the water temperature sensor 33 to the traction control permission judging section 51. A map that has been obtained and stored in advance by experiments, etc. (for example, shown in FIG. 4)
O for the engine water temperature at engine start
(2) The time after starting when the sensor 34 is activated and the air-fuel ratio control becomes possible is read. Then, the time after starting from this map is compared with the time from when the engine 1 is started to the present, and if the time after starting the engine to the present exceeds the time after starting according to the map, the engine is empty. It is determined that the fuel ratio control can be executed and the engine output can be controlled by the traction control. That is, the traction control permission determination unit 51 has the functions of the air-fuel ratio control execution determination unit and the traction control permission unit, and the determined traction control permission signal is the throttle valve control unit 52.
Is output to.

The throttle valve control section 52 receives the engine target torque and a signal for executing traction control from the traction control section 40, and receives the traction control permission judging section 5
1, a traction control permission signal is input, and signals from other switches and sensors (not shown) such as a crank angle sensor, an air flow sensor, an air conditioner switch, a throttle sensor, and an accelerator sensor are input.

In a normal control, the throttle valve control section 52 sets an engine output target value from the accelerator opening degree and the engine speed, etc., as is well known, and the fuel injection is performed according to the engine output target value. In addition to controlling the amount, adjust the throttle valve opening to control the intake air amount,
The control for improving the responsiveness to the output required by the driver and obtaining good running performance is executed. Further, when the engine output is reduced by the traction control, the actual engine torque is set to the engine target torque by the traction control device 40 only when a traction control permission signal is input from the traction control permission determination unit 51. The control of the electronically controlled throttle valve 25 to be brought close to is executed by, for example, proportional-plus-integral control or the like, and a signal is output to the throttle motor 26. If the traction control permission signal is not input from the traction control permission determination unit 51, that is, if the traction control is not permitted,
Even if the engine target torque and the signal for executing the traction control are input from the traction control unit 40, the traction control is prohibited.

Next, the procedure of the traction control permission judgment in the engine control unit 50 will be described with reference to the flowchart of FIG.

First, step (hereinafter abbreviated as "S") 1
In reference numeral 01, for example, referring to a map obtained by experiments or the like in advance and stored as shown in FIG. 4, the O2 sensor 34 is activated with respect to the engine water temperature at the time of engine start and the air-fuel ratio control becomes possible after start. Read the time.

Then, in S102, the post-start time from the map read in S101 is compared with the time from when the engine 1 is started to the present time, and it is determined whether the air-fuel ratio control can be executed.

As a result of the determination in S102, if the time from the engine start to the present time exceeds the map start time, it is determined that the engine air-fuel ratio control can be executed.
In step S103, the engine output control by traction control is permitted, and the program exits.

On the contrary, as a result of the determination in S102, if the time from the engine start to the present has not reached the map start time, the process proceeds to S104, the engine output control by the traction control is prohibited, and the program is executed. Get out.

That is, in general, in the engine control, when the air-fuel ratio control cannot be performed, the fuel and the ignition timing are adjusted by the open loop control to maintain the engine speed. Therefore, it is set so that it cannot follow transient movements. In such a state, if the traction control operates and the torque of the engine output is reduced, the control may not be optimally performed. However, in the state where the air-fuel ratio can be controlled even if the engine water temperature is low, the fuel feedback control can be performed according to the output of the air-fuel ratio sensor, so even if the torque reduction of the engine output by the traction control is instructed, the feedback control is sufficiently performed. Is possible. Therefore, it is determined whether the air-fuel ratio control of the engine is feasible, and if it is determined that the air-fuel ratio control of the engine is feasible, the engine output is controlled by the traction control to allow the driver to output the engine output according to the operating state. It is possible to enjoy the reduced traction control function in the shortest possible time after the engine is started.

[0032]

As described above, according to the present invention,
Even in a vehicle without an automatic braking system,
In addition, it is possible to allow the driver to enjoy the function of the traction control for reducing the engine output according to the driving state in the shortest possible time after starting the engine with a simple configuration without making the system large and complicated.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a vehicle drive system, a traction control device, and an engine control device.

FIG. 2 is a schematic configuration explanatory view of an electronically controlled throttle valve.

FIG. 3 is a functional block diagram of traction control in the engine control device.

FIG. 4 is a characteristic explanatory diagram of a water temperature at the time of starting and a time after starting that enables traction control.

FIG. 5 is a flowchart of traction control permission determination in the engine control device.

[Description of Reference Signs] 1 engine 33 water temperature sensor 34 O 2 sensor (air-fuel ratio sensor) 40 traction control device (traction control means) 50 engine control device 51 traction control permission determination unit (air-fuel ratio control execution determination means, traction control permission means)

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02D 45/00 368 F02D 45/00 368F

Claims (2)

[Claims] 1. A vehicle having traction control means for reducing at least an engine output according to a driving state to maintain a predetermined vehicle behavior, and performing air-fuel ratio control based on a signal from an air-fuel ratio sensor provided in an exhaust system. In this engine control device, the air-fuel ratio control execution determining means for determining whether the engine air-fuel ratio control is feasible, and the traction control when the air-fuel ratio control execution determining means determines that the engine air-fuel ratio control is executable An engine control device for a vehicle, comprising: traction control permission means for permitting control of engine output by the vehicle. 2. The air-fuel ratio control execution determining means determines whether the air-fuel ratio control of the engine can be executed according to the engine water temperature at the time of starting the engine and the elapsed time from the start of the engine. The engine control device for a vehicle according to claim 1, wherein the engine control device is for a vehicle.