JP7229834B2 - VALVE PHASE DETERMINATION METHOD WHEN STARTING INTERNAL COMBUSTION ENGINE AND VEHICLE OPERATION CONTROL DEVICE - Google Patents

Description

TECHNICAL FIELD The present invention relates to a valve phase determining method and a vehicle operation control device at the time of starting an internal combustion engine, and more particularly to a method for improving the starting characteristics of an internal combustion engine.

In automobiles, in order to improve the fuel efficiency and driving performance of internal combustion engines, a variable valve timing (VVT) device is used that makes it possible to adjust the valve phase, which is the valve position when the valve opens and closes. It is well known that

There are two types of variable valve timing (hereinafter referred to as "VVT") devices: a hydraulically driven VVT device configured to adjust the valve phase by hydraulic pressure, and an electrically driven VVT device configured to adjust the valve phase using an electric motor. There are types.
An electrically driven VVT device has the advantage that it is less restricted by environmental conditions such as temperature and can be used in a wider range than a hydraulically driven VVT device.

On the other hand, because of the structure of the hydraulically driven VVT device, the valve phase returns to the initial position after the engine is stopped. and ensure a smooth restart of the engine.

On the other hand, in the case of an electrically driven VVT device, structurally, unlike the hydraulically driven VVT device described above, the valve phase does not return to the initial position after the engine is stopped. It is difficult to provide, and the structure without a locking mechanism is common.
Therefore, after system shutdown (ignition off) of the vehicle, there is a possibility that the valve phase may change from when the system was shut down, such as when an external force is applied to the vehicle.

Therefore, when the ignition switch is subsequently turned on, the valve phase may differ from that at the time of the most recent system shutdown. You may be invited.

Therefore, in a vehicle using an electrically driven VVT device, it is essential to recognize the valve phase when the engine is started.
Generally, when starting an engine, it is necessary to know the positions of the cylinders and valves at the time of starting. A method of discriminating the cylinders of the engine and calculating the valve phase using this method is known, but there are the following problems.

JP-A-2003-56381

In the method of discriminating the cylinders of the engine using the crank angle detected by the crank angle sensor and the cam angle detected by the cam angle sensor, the slowness of the cylinder discrimination usually depends on the rotation speed of the starter. Therefore, for example, in a low temperature environment, as the battery voltage drops, the starter rotation speed decreases, so the time required for cylinder discrimination is longer than normal, and the engine start time is longer than at room temperature. There is

Also, in this method, the valve phase cannot be determined until the cylinder discrimination is completed, so the valve phase cannot be changed until then. Become.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for determining a valve phase at the start of an internal combustion engine and a vehicle operation control apparatus, which can determine the valve phase at an early stage when the internal combustion engine is started.

In order to achieve the object of the present invention, a method for determining a valve phase at the start of an internal combustion engine according to the present invention comprises:
A method for determining the valve phase at the start of an internal combustion engine for determining the valve phase at the start of the internal combustion engine having a variable valve timing device configured to be able to adjust the valve phase of the internal combustion engine, comprising:
When the internal combustion engine is started, the variable valve timing device displaces the valve phase to the most retarded position, and whether or not the valve phase deviation, which is the difference between the output values of the cam angle sensor before and after the time, is below a predetermined reference deviation. When the valve phase deviation falls below the reference deviation, the valve phase is determined as having reached the most retarded position, and the valve phase is determined, and is used for start control of the internal combustion engine ,
The variable valve timing device is configured to be able to adjust the valve phase by electric drive, and is used to adjust the intake valve phase,
A series of processes for determining the valve phase is stopped when the valve phase is not determined when the cylinder determination process is executed separately and the cylinder determination is completed.
Further, in order to achieve the object of the present invention, a vehicle motion control device according to the present invention includes:
A vehicle operation control device configured to be able to execute operation control of an internal combustion engine having a variable valve timing device configured to adjust a valve phase of the internal combustion engine using an electronic control unit,
The electronic control unit is
When the internal combustion engine is started, the valve phase is displaced to the most retarded position by the variable valve timing device, and whether or not the valve phase deviation, which is the difference between the output values of the cam angle sensor before and after the time, has fallen below a predetermined reference deviation. When the valve phase deviation is less than the reference deviation, the valve phase is determined as having reached the most retarded position, and the valve phase is determined and used for start control of the internal combustion engine ;
The variable valve timing device is configured to be able to adjust the valve phase by electric drive, and is used to adjust the intake valve phase,
The electronic control unit is
The cylinder discrimination process of the internal combustion engine can be executed separately, and when the cylinder discrimination process is completed by the cylinder discrimination process, if the valve phase is not determined, the series of processes for determining the valve phase is stopped. It is configured to

According to the present invention, while forcibly changing the valve phase with the most retarded position as the target, when the change in the output value of the cam angle sensor becomes equal to or less than a predetermined value, the valve phase becomes the most retarded angle, which is the end point. By judging that the position has been reached, it is possible to determine the valve phase early at the time of starting. This makes it possible to determine the phase, thereby shortening the start-up time of the internal combustion engine and improving the reliability of the start-up.

1 is a configuration diagram showing a configuration example of a vehicle motion control device according to an embodiment of the present invention; FIG. 1 is a configuration diagram showing a system configuration example of an electric system for executing valve phase determination processing at internal combustion engine start-up by a vehicle operation control device according to an embodiment of the present invention; FIG. 4 is a subroutine flow chart showing the procedure of valve phase determination processing at internal combustion engine start-up executed in the vehicle operation control system according to the embodiment of the present invention; FIG. 4A is a schematic diagram for explaining the state change of the main part when the internal combustion engine starting valve phase determining process is executed in the embodiment of the present invention, FIG. FIG. 4B is a schematic diagram for explaining the change between the target phase angle of the valve set in the electrically driven VVT device and the actual phase angle of the valve, and FIG. FIG. 4(D) is a schematic diagram for explaining the timing of starting cranking, FIG. 4(E) is a schematic diagram for explaining changes in the engine speed, and FIG. 4(F) is a cylinder discrimination FIG. 4(G) is a schematic diagram for explaining the ignition start time.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. FIG.
The members, arrangement, etc., described below do not limit the present invention, and can be modified in various ways within the spirit and scope of the present invention.
First, a configuration example of a vehicle operation control system to which the internal combustion engine starting valve phase determination method according to the embodiment of the present invention is applied will be described with reference to FIGS. 1 and 2. FIG.

The vehicle motion control device according to the embodiment of the present invention is particularly suitable for valve phase control by an electrically driven VVT device (details will be described later).
That is, the vehicle operation control device according to the embodiment of the present invention includes an engine ECU (denoted as "E-ECU" in FIG. 1) 51 using an electronic control unit, an electrically driven VVT device 1, and a crank angle sensor. 2, a cam angle sensor 3, and an electrically driven VVT motor rotation speed sensor 4 as main components.

As in the conventional art, the engine ECU 51 is configured to be capable of executing various controls necessary for vehicle running control, such as rotation control of the engine 5 as an internal combustion engine and fuel injection control.
The engine ECU 51 includes, for example, a microcomputer having a well-known configuration, storage elements (not shown) such as RAM and ROM, and an input/output interface circuit (not shown). It is configured as a component.

The engine ECU 51 receives detection signals from the crank angle sensor 2, the cam angle sensor 3, and the electrically driven VVT motor rotational speed sensor 4, as well as various signals required for vehicle operation control detected by sensors (not shown). , accelerator opening, vehicle speed, and the like are input. Various signals input to the engine ECU 51 are used for engine rotation control, fuel injection control, and valve phase determination processing at the time of starting the internal combustion engine in an embodiment of the present invention, which will be described later. .

The electrically driven VVT device 1 is a variable valve timing (VVT) device. This electrically driven VVT device 1 is constructed so that the valve phase can be adjusted by an electrically driven VVT actuator 1a (see FIG. 2) using a motor. be.

It is assumed that the electrically driven VVT device 1 is provided in at least one of an intake valve (not shown) and an exhaust valve (not shown) of an engine 5 as an internal combustion engine. In the embodiment of the present invention, the electrically driven VVT device 1 is arranged on the intake valve side.

In the engine 5, power obtained by the crankshaft 6 is transmitted to an intake camshaft 11 and an exhaust camshaft 12 via sprockets 8 and 9 by a timing belt (or timing chain) 7. .

A crank wheel having a plurality of protrusions 13 protruding from its outer circumference is attached to the crank shaft 6, and a crank angle sensor 2 is provided in the vicinity thereof.
Similarly, the intake camshaft 11 is attached with a cam wheel having a plurality of protrusions 14 protruding from its outer circumference, and a cam angle sensor 3 is provided in the vicinity thereof.

These crank wheel, cam wheel, crank angle sensor 2 and cam angle sensor 3 are basically the same as conventional ones.
That is, the crank angle sensor 2 can output a pulse signal in response to the passage of the projection 13 of the crank wheel, and the cam angle sensor 3 can output a pulse signal in response to the passage of the projection 14 of the cam wheel.

The above-described pulse signals are input to the engine ECU 51, and the rotation speed of the crankshaft 6 and the rotation speed of the intake camshaft 11 are calculated based on the pulse signal input interval, the number of inputs, and the like. .

In the embodiment of the present invention, a body ECU (referred to as a "B-ECU" in FIG. 2), which is an electronic control unit that controls the operation of electric devices other than the engine 5, is separate from the engine ECU 51. notation) 52 is provided. The body ECU 52 executes, for example, drive control of the starter motor 23 (see FIG. 2).
Both the body ECU 52 and the engine ECU 51 receive power supply voltage from a vehicle battery ("BAT" in FIG. 2) 22 via an ignition switch ("IG-SW" in FIG. 2) 21. It is designed to receive (see Figure 2).

FIG. 3 shows a subroutine flowchart showing the procedure of the valve phase determining process at the start of the internal combustion engine according to the embodiment of the present invention, which is executed by the engine ECU 51. Hereinafter, the content of the subroutine will be described with reference to the same figure. explain.
First, the engine ECU 51 according to the embodiment of the present invention is based on the premise that the so-called cylinder discrimination process is executed simultaneously and in parallel with the internal combustion engine starting valve phase determination process, as in the conventional case. do. There are various methods of cylinder discrimination, but there is no need to be limited to a specific method.

On this premise, when the ignition switch 21 is turned on, power supply to the engine ECU 51 is started, and the electrically driven VTT device 1 is started (see step S100 in FIG. 3).
Next, the valve phase is set and the valve is driven by the electrically driven VVT device 1 (see step S200 in FIG. 2).

Here, prior to detailed description of the internal combustion engine starting valve phase determining process according to the embodiment of the present invention, the overall procedure of the process will be generally described.
The valve phase determining process at the start of the internal combustion engine according to the embodiment of the present invention is to determine the valve phase of an intake valve (not shown) at an early stage when the engine 5 is started, and to use it for internal combustion engine start control. , the start-up time can be shortened and the start-up reliability can be improved.

Specifically, in step S200, the intake valve (not shown) is displaced, in other words, the intake camshaft 11 is rotated by the displacement amount (rotational angle). A target VVT angle is set. Next, an intake valve (not shown) is displaced by the electrically driven VVT actuator 1a according to the target VVT angle.

The driving of the electrically driven VVT actuator 1a based on this target VVT angle is repeated multiple times in order to finally position the intake valve (not shown) at the most retarded position as a predetermined end point.
Here, the target VVT angle is not limited to a specific value. (not shown) is determined to have reached the most retarded position, it is preferable to choose a relatively small angle.

Then, the valve phase deviation Δθ is calculated (see step S300 in FIG. 3).
Here, the valve phase deviation .DELTA..theta. is the difference between the output values of the cam angle sensor 3 before and after the execution of step S300.
That is, for example, let θdet(n) be the latest output value of the cam angle sensor 3, and let θdet(n-1) be the latest output value of the cam angle sensor 3 before obtaining this output value θdet(n). The valve phase deviation .DELTA..theta. is calculated as .DELTA..theta.=.theta.det(n)-.theta.det(n-1).

Next, it is determined whether or not the cylinder discrimination process has been completed (see step S400 in FIG. 3).
As described above as a prerequisite for the engine ECU 51 in the embodiment of the present invention, the cylinder determination process is executed separately from the valve phase determination process based on the conventional method.

If it is determined in step S400 that the cylinder discrimination has been completed (if YES), the phase of the intake valve (not shown) (hereinafter referred to as "intake valve phase" for convenience of explanation) is also determined. Therefore, there is no need to continuously execute the valve phase determining process at the time of starting the internal combustion engine. Therefore, in this case, valve position control at the time of starting the engine 5 is performed based on the result of cylinder discrimination, and ignition in the engine 1 is started (see step S700 in FIG. 3).

On the other hand, if it is determined in step S400 that cylinder discrimination has not been completed (if NO), end point determination is performed using the valve phase deviation Δθ (see step S500 in FIG. 3).
That is, it is determined whether or not the absolute value of the valve phase deviation .DELTA..theta. calculated in step S300 is lower than the reference deviation .theta.s.

This determination process is performed from the viewpoint described below.
While the intake valve phase follows the target VVT angle and changes toward the most retarded position, which is the final target position, the latest cam angle sensor 3 output value θdet(n) and the latest cam angle sensor There is always a difference between the output value .theta.det(n-1) of 3 and .theta.det(n-1).
In other words, the latest output value θdet(n) is always larger than the latest output value θdet(n−1), and its magnitude depends on the rotation angle of the intake camshaft 11 by the electrically driven VVT actuator 1a. It will correspond.

However, when the intake valve phase reaches the most retarded position, the change in the output of the cam angle sensor 3 theoretically stops at the output value at that time. Therefore, the valve phase deviation .DELTA..theta. at this time is theoretically zero, but in practice it may not always be zero due to variations in the output characteristics of the cam angle sensor 3 and the like. Therefore, in the embodiment of the present invention, it is determined that the intake valve phase has reached the most retarded position when the absolute value of the valve phase deviation Δθ is less than the reference deviation θs.

If it is determined in step S500 that the absolute value of the valve phase deviation .DELTA..theta. assumed to have arrived. Then, the most retarded position of the intake valve phase at this time is stored and held in an appropriate storage area of the engine ECU 51 as a learning value of the intake phase (step S600 in FIG. 3).
Next, based on the intake valve phase determined as described above, valve position control is performed when the engine 5 is started, and ignition in the engine 1 is started (see step S700 in FIG. 3).

Next, referring to the schematic diagram shown in FIG. 4, a general description will be given of the valve phase determining process at the start of the internal combustion engine according to the embodiment of the present invention.
When the ignition switch 21 is turned on (see time t1 in FIG. 4A) and the engine ECU 51 starts the electrically driven VVT device 1, the intake valve (not shown) is displaced to the most retarded position. , the setting of the target VVT angle and the driving of the intake valve (not shown) by the electrically driven VVT actuator 1a according to the target VVT angle are repeated multiple times (see FIG. 4B after time t2).

In FIG. 4B, the change in the target VVT angle is indicated by a two-dot chain line, and the change in the valve phase (actual angle) detected by the cam angle sensor 3 is indicated by a solid line. Both are from the start of driving the intake valve (not shown) by the electrically driven VVT actuator 1a (time t2 in FIG. 4(B)) until the actual angle reaches the end point position (time t4 in FIG. 4(B)). , and the actual angle from the end point position to the optimum VVT phase position. , are shown parallel and spaced apart for ease of understanding.

As described above, when the intake valve (not shown) is repeatedly driven by the electrically driven VVT actuator 1a according to the target VVT angle, when cranking is started (see time t3 in FIG. 4D). , the engine speed gradually increases (see FIG. 4(E)).
On the other hand, as described above, the intake valve (not shown) is driven by the electrically driven VVT actuator 1a in accordance with the VVT target angle until the absolute value of the valve phase deviation Δθ falls below the reference deviation Δθs. When it is determined that the absolute value of the valve phase deviation .DELTA..theta. reference).

At this point in time, if cylinder discrimination has not been completed by the cylinder discrimination process that is executed separately from the internal combustion engine starting valve phase determination process (see time t6 in FIG. 4(F)), the internal combustion engine is started. Valve position control is performed by the electrically driven VTT actuator 1a based on the intake valve phase determined by the hour valve phase determination process, and ignition in the engine 1 is started (time t7 in FIG. 4G). reference).

Thus, by applying the valve position determination process at the time of starting the internal combustion engine according to the embodiment of the present invention, the valve position is determined earlier than when the valve position at the time of starting is determined by the conventional cylinder discrimination process. The opportunity to do so will increase and the start-up time will be shortened.

In addition, after the valve position is determined, there are more opportunities to secure sufficient time to drive and control the VVT to the optimum valve phase for engine starting, and by ensuring good combustion at engine start, As a result, the occurrence of misfires and abnormal combustion is reduced.
Furthermore, since the start-up time can be shortened, the emission of non-combustible HC (hydrocarbons) and harmful gases can be reduced. Shortening the start-up time also makes it possible to warm up the catalyst at an early stage, and an effect of reducing emissions of harmful gases due to the early warm-up of the catalyst can be expected.

It can be applied to a vehicle in which it is desired to determine the valve position at an early stage when starting the internal combustion engine.

DESCRIPTION OF SYMBOLS 1... Electric drive VVT apparatus 2... Crank angle sensor 3... Cam angle sensor 6... Crankshaft 11... Intake camshaft 12... Exhaust camshaft

Claims (2)

A method for determining the valve phase at the start of an internal combustion engine for determining the valve phase at the start of the internal combustion engine having a variable valve timing device configured to be able to adjust the valve phase of the internal combustion engine, comprising:
When the internal combustion engine is started, the variable valve timing device displaces the valve phase to the most retarded position, and whether or not the valve phase deviation, which is the difference between the output values of the cam angle sensor before and after the time, is below a predetermined reference deviation. When the valve phase deviation falls below the reference deviation, the valve phase is determined as having reached the most retarded position, and the valve phase is determined, and is used for start control of the internal combustion engine,
The variable valve timing device is configured to be able to adjust the valve phase by electric drive, and is used to adjust the intake valve phase,
When a cylinder discrimination process is separately executed and the cylinder discrimination is completed, if the valve phase is not determined, a series of processes for determining the valve phase is stopped. Valve phase determination method. A vehicle operation control device configured to be able to execute operation control of an internal combustion engine having a variable valve timing device configured to adjust a valve phase of the internal combustion engine using an electronic control unit,
The electronic control unit is
When the internal combustion engine is started, the variable valve timing device displaces the valve phase to the most retarded position, and whether or not the valve phase deviation, which is the difference between the output values of the cam angle sensor before and after the time, is below a predetermined reference deviation. When the valve phase deviation falls below the reference deviation, the valve phase is determined as having reached the most retarded position, and the valve phase is determined, and is used for start control of the internal combustion engine,
The variable valve timing device is configured to be able to adjust the valve phase by electric drive, and is used to adjust the intake valve phase,
The electronic control unit is
The cylinder discrimination process of the internal combustion engine can be executed separately, and when the cylinder discrimination process is completed by the cylinder discrimination process, if the valve phase is not determined, the series of processes for determining the valve phase is stopped. A vehicle motion control device characterized by being configured to:

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