JP2002147280A - Engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lighten labor required to prepare a map to compute a fuel injection quantity, and to eliminate a throttle valve. SOLUTION: The mass of air in a cylinder is computed from an engine speed and an intake air pipe pressure in accordance with a map to compute the mass of the air in the cylinder, and a target air-fuel ratio is computed from the engine speed and the intake air pipe pressure in accordance with a map to compute the air-fuel ratio. The mass of required fuel is computed by dividing the mass of the air in the cylinder by the target air-fuel ratio, and the fuel injection quantity is computed by multiplying it by the flow characteristics of an injector. The map to compute the mass of the air in the cylinder can be prepared only by measuring the mass by changing the engine speed and the intake air pipe pressure, and the map to compute the target air-fuel ratio can be set to a certain degree by the output characteristics of a required engine. When accelerating or reducing a speed, compensation for a transient period to shift the target air-fuel ration to the rich side or to the lean side is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device for controlling an engine, and is particularly suitable for controlling an engine having a fuel injection device for injecting fuel.

[0002]

2. Description of the Related Art In recent years, as fuel injectors called injectors have become widespread, it has become easier to control the timing of fuel injection and the amount of injected fuel, that is, the air-fuel ratio, to achieve higher output, lower fuel consumption, and cleaner exhaust gas. Can be promoted. Of these, particularly regarding the fuel injection timing, strictly speaking, the state of the intake valve, that is, generally, the phase state of the camshaft is generally detected, and the fuel is generally injected in accordance therewith.
However, a so-called cam sensor for detecting the phase state of the camshaft is expensive, and cannot be adopted particularly in a motorcycle or the like due to a problem such as an increase in the size of a cylinder head. Therefore, for example, Japanese Patent Application Laid-Open No. H10-227
Japanese Patent Publication No. 252 proposes an engine control device that detects a phase state of a crankshaft and an intake pipe pressure, and detects a stroke state of a cylinder based on the phase state and the intake pipe pressure. Therefore, by using this conventional technique, the stroke state can be detected without detecting the phase of the camshaft.
The fuel injection timing and the like can be controlled according to the stroke state.

[0003]

Incidentally, in order to control the fuel injection amount injected from the fuel injection device as described above, a target air-fuel ratio corresponding to, for example, the engine speed and the throttle opening is set, and the actual air-fuel ratio is set. By detecting the intake air amount and multiplying the inverse ratio of the target air-fuel ratio, the target fuel injection amount can be calculated.

In order to detect the amount of intake air, a hot wire airflow sensor or a Karman eddy current sensor is generally used.
These are used as sensors for measuring the mass flow rate and volume flow rate respectively. However, in order to eliminate the error factors due to the backflowing air, a volume body (surge tank) that suppresses pressure pulsation
Or installation at a position where the backflow air does not enter. However, many motorcycle engines have a so-called independent intake system for each cylinder, or the engines themselves are single-cylinder engines, and these requirements cannot be sufficiently satisfied in many cases. Even if a flow sensor is used, the amount of intake air cannot be accurately detected. In addition, at least the current sensors cannot accurately detect a small amount of intake air, particularly in an independent intake system engine or a single cylinder engine of a motorcycle.

[0005] As described above, in an engine with a fuel injection device that cannot detect an intake air amount, a three-dimensional map corresponding to these parameters is generally used by using an engine load such as a throttle opening and an engine operating state such as an engine speed. For example, the fuel injection time can be set directly.
However, since it is not possible to easily calculate the output or torque of the engine using the air-fuel ratio, the engine load, and the engine operating state as parameters, the map changes the parameters of the engine load and the engine operating state little by little. Measure how much output or torque is obtained at what air-fuel ratio, and set the air-fuel ratio so that the desired output or torque is obtained,
For example, the fuel injection time must be set so as to obtain the air-fuel ratio. That is, a map must be created so that the required output characteristics can be obtained while measuring data at all the intersections of the grid of the map. Also, depending on how the map is set, the output characteristics of the engine are different. Conversely, if the required output characteristics are different even for engines of a similar type, a new map must be created. In short, since the map itself is composed of numerical values whose physical meaning is difficult to grasp, it is very difficult and time-consuming to create the map.

In the map, a throttle opening sensor is required because the throttle opening is used as a parameter. However, both the throttle opening sensor and the throttle position sensor for detecting the position of the throttle itself are expensive. There is a demand that they do not want to adopt this technology especially for motorcycles. The present invention has been developed in order to solve the above-mentioned problems, and the map can be controlled by using a map whose physical meaning is easy to grasp and a map easy to measure or set. It is an object of the present invention to provide an engine control device which is easy to prepare and does not require a throttle sensor such as a throttle opening sensor and a throttle position sensor.

[0007]

An engine control device according to a first aspect of the present invention includes an intake pipe pressure detecting means for detecting an intake pipe pressure in an intake pipe of an engine, and an engine operating state. From the operating state detecting means for detecting, and the intake pipe pressure detected by the intake pipe pressure detecting means and the operating state of the engine detected by the operating state detecting means, the intake air amount is calculated according to a previously stored intake air amount map. The target air-fuel ratio is calculated according to a target air-fuel ratio map stored in advance from the calculated intake air amount calculating means, and the intake pipe pressure detected by the intake pipe pressure detecting means and the operating state of the engine detected by the operating state detecting means. And a fuel injection device based on the intake air amount calculated by the intake air amount calculation means and the target air-fuel ratio calculated by the target air-fuel ratio calculation means. It is characterized in that a fuel injection amount calculating means for calculating a fuel injection amount to be injected from.

According to a second aspect of the present invention, in the engine control apparatus according to the first aspect of the present invention, the target air-fuel ratio calculating means is configured to detect a transient from the intake pipe pressure detected by the intake pipe pressure detecting means. The present invention is characterized in that a transient period correcting means for detecting that the current period is a period and correcting the target air-fuel ratio is provided. An engine control device according to a third aspect of the present invention is the engine control device according to the first or second aspect, wherein the operating state detecting means detects an engine speed from a phase of a crankshaft. It is characterized by having.

[0009]

Embodiments of the present invention will be described below. FIG. 1 is a schematic configuration showing an example of an engine for a motorcycle and a control device thereof. The engine 1 is a four-cylinder four-cycle engine, and includes a cylinder body 2, a crankshaft 3, a piston 4, a combustion chamber 5, an intake pipe 6, an intake valve 7, an exhaust pipe 8, an exhaust valve 9, a spark plug 10, an ignition coil 11 is provided. A throttle valve 12 that opens and closes in accordance with the accelerator opening is provided in the intake pipe 6, and an injector 13 as a fuel injection device is provided in the intake pipe 6 upstream of the throttle valve 12. . This injector 1
3 is a filter 1 provided in the fuel tank 19.
8, connected to the fuel pump 17 and the pressure control valve 16. The engine 1 is a so-called independent intake system.
The injector 13 is provided in each intake pipe 6 of each cylinder.

The operating state of the engine 1 is controlled by an engine control unit 15. And
As means for detecting the control input of the engine control unit 15, that is, the operating state of the engine 1, a crank angle sensor 20 for detecting the rotation angle of the crankshaft 3, that is, the phase, the temperature of the cylinder body 2 or the cooling water temperature, That is, a cooling water temperature sensor 21 for detecting the temperature of the engine body, an exhaust air-fuel ratio sensor 22 for detecting an air-fuel ratio in the exhaust pipe 8, an intake pipe pressure sensor 24 for detecting an intake pipe pressure in the intake pipe 6, an intake air An intake air temperature sensor 25 for detecting the temperature in the pipe 6, that is, the intake air temperature is provided. Then, the engine control unit 15
Receives the detection signals of these sensors and outputs control signals to the fuel pump 17, pressure control valve 16, injector 13, and ignition coil 11.

The engine control unit 15
Is constituted by a microcomputer (not shown) or the like. FIG. 2 is a block diagram showing an embodiment of the engine control arithmetic processing performed by the microcomputer in the engine control unit 15. In this calculation process, an engine speed calculating unit 26 for calculating the engine speed from the crank angle signal, and crank timing information, that is, a crank timing detecting unit 27 for detecting the stroke state from the crank angle signal and the intake pipe pressure signal. And the crank timing information detected by the crank timing detection unit 27 is read and calculated by the intake air temperature signal, the cooling water temperature (engine temperature) signal, the intake pipe pressure signal, and the engine speed calculation unit 26. A cylinder air mass calculation unit (intake air amount calculation means) 28 for calculating the air mass in the cylinder (intake air amount) from the engine speed, and the engine speed calculation unit 2
6, a target air-fuel ratio calculating section 33 for calculating a target air-fuel ratio from the engine speed and the intake pipe pressure signal, and a target air-fuel ratio calculated by the target air-fuel ratio calculating section 33 and the intake pipe pressure signal. The cylinder air mass calculator 2
The fuel injection amount calculation unit 34 that calculates the fuel injection amount and the fuel injection timing from the cylinder air mass calculated in step 8 and the crank timing information detected by the crank timing detection unit 27 are read. An injection pulse output unit 30 that outputs an injection pulse corresponding to the fuel injection amount and the fuel injection timing calculated at 34 to the injector 13; an engine speed calculated by the engine speed calculation unit 26; The ignition timing calculator 31 calculates the ignition timing from the target air-fuel ratio set by the air-fuel ratio calculator 33, and the crank timing information detected by the crank timing detector 27 is read and set by the ignition timing calculator 31. And an ignition pulse output unit 32 that outputs an ignition pulse corresponding to the ignition timing to the ignition coil 11. It is.

The engine speed calculation unit 26 calculates the rotation speed of the crankshaft, which is the output shaft of the engine, as the engine speed from the time change rate of the crank angle signal. The crank timing detecting section 27 has a configuration similar to that of the stroke discriminating apparatus described in Japanese Patent Laid-Open No. Hei 10-227252.
As shown in (1), the stroke state of each cylinder is detected and output as crank timing information. That is, in a four-cycle engine, since the crankshaft and the camshaft are constantly rotating with a predetermined phase difference, for example, when a crank pulse is read as shown in FIG.
The crank pulse indicated by “4” is either the exhaust stroke or the compression stroke. As is well known, the exhaust valve is closed during the exhaust stroke, and the intake pipe pressure is high because the intake valve is closed. At the beginning of the compression stroke, the intake pipe pressure is low because the intake valve is still open, or the intake valve is low. Is closed, the intake pipe pressure is low in the preceding intake stroke. Accordingly, when the intake pipe pressure is low, the crank pulse of "4" shown in the drawing indicates that the second cylinder is in the compression stroke, and when the crank pulse of "3" shown is obtained, the crank pulse of the second cylinder is lower. Become a dead center. If the stroke state of any one of the cylinders can be detected in this manner, each cylinder is rotating with a predetermined phase difference. For example, the crank pulse of "3" shown in FIG. The next illustrated “9” crank pulse is the intake bottom dead center of the first cylinder, the next illustrated “3” crank pulse is the intake bottom dead center of the third cylinder, and the next illustrated “9”. Is the intake bottom dead center of the fourth cylinder. Then, by interpolating during this stroke with the rotation speed of the crankshaft, the current stroke state can be detected more finely.

As shown in FIG. 4, the cylinder air mass calculator 28 calculates the cylinder air mass from the intake pipe pressure signal and the engine speed calculated by the engine speed calculator 26. It has a three-dimensional map. This three-dimensional map of the air mass in the cylinder, for example, only needs to measure the air mass in the cylinder when the intake pipe pressure is changed while actually rotating the engine at a predetermined number of revolutions, and by a relatively simple experiment It can be measured and therefore the map is easy to create. If an advanced engine simulation is available, a map can be created using the advanced engine simulation. The air mass in the cylinder is
Since it changes depending on the temperature of the engine, it may be corrected using the cooling water temperature (engine temperature) signal.

As shown in FIG. 5, the target air-fuel ratio calculator 33 calculates a three-dimensional target air-fuel ratio from the intake pipe pressure signal and the engine speed calculated by the engine speed calculator 26. It has a map. This three-dimensional map can be set to some extent even on a desk. The air-fuel ratio generally has a correlation with the torque. When the air-fuel ratio is small, that is, when the amount of fuel is large and the amount of air is small, the efficiency increases while the torque increases. Conversely, when the air-fuel ratio is large, that is, when the amount of fuel is small and the amount of air is large, the torque is reduced, but the efficiency is improved. The state in which the air-fuel ratio is small is called rich, and the state in which the air-fuel ratio is large is called lean. The leanest state is called a so-called ideal air-fuel ratio or stoichiometric air-fuel ratio at which gasoline is completely burned, that is, 14.
7

The engine speed is the operating state of the engine. Generally, the air-fuel ratio is increased on the high speed side and decreased on the low speed side. This is to increase the response of the torque on the low rotation side and to increase the response of the rotation state on the high rotation side.
In addition, the intake pipe pressure is an engine load state such as a throttle opening degree. In general, the engine load is large, that is, the air-fuel ratio is reduced when the throttle opening degree is large and the intake pipe pressure is large, and the engine load state is small. That is, when the throttle opening is small and the intake pipe pressure is also small, the air-fuel ratio is increased. This is because the importance is placed on the torque when the engine load is large, and on the efficiency when the engine load is small.

As described above, the target air-fuel ratio is a numerical value whose physical meaning can be easily grasped. Therefore, the target air-fuel ratio can be set to some extent in accordance with the required output characteristics of the engine. Of course, it goes without saying that tuning may be performed in accordance with the engine output characteristics of the actual vehicle. The target air-fuel ratio calculating unit 33 detects a transition period of the operating state of the engine from the intake pipe pressure signal, specifically, an acceleration state or a deceleration state, and corrects the target air-fuel ratio accordingly. A portion 29 is provided. For example, as shown in FIG. 6, since the intake pipe pressure is also a result of the throttle operation, when the intake pipe pressure increases, it is understood that the throttle is opened and acceleration is required, that is, the vehicle is in an accelerated state. . When such an acceleration state is detected, the target air-fuel ratio is temporarily set to the rich side, for example, and then returned to the original target air-fuel ratio. An existing method can be used to return to the target air-fuel ratio, for example, by gradually changing the weighting coefficient of the weighted average of the air-fuel ratio set to the rich side in the transition period and the original target air-fuel ratio. Conversely, when a deceleration state is detected, the efficiency may be emphasized by setting the air-fuel ratio leaner than the original target air-fuel ratio.

In the fuel injection amount calculating section 34,
By dividing the cylinder air mass calculated by the cylinder air mass calculation unit 28 by the target air-fuel ratio calculated by the target air-fuel ratio calculation unit 33, the required fuel mass in the cylinder can be obtained. Is multiplied by, for example, the flow rate characteristic of the injector 13 to determine the fuel injection time, and from this, the fuel injection amount and the fuel injection timing can be calculated.

As described above, in the present embodiment, the cylinder air mass is calculated from the intake pipe pressure and the operating state of the engine according to a three-dimensional map of the cylinder air mass stored in advance, and the intake pipe pressure and the engine pressure are calculated. From the operating state, the target air-fuel ratio is calculated according to the target air-fuel ratio map stored in advance, and the fuel injection amount can be calculated by dividing the air mass in the cylinder by the target air-fuel ratio. In addition to being accurate, the in-cylinder air mass map is easy to measure and the target air-fuel ratio map is easy to set, so that the map creation is easy. Further, a throttle sensor such as a throttle opening sensor and a throttle position sensor for detecting an engine load is not required.

Further, by detecting a transition period such as an acceleration state or a deceleration state from the intake pipe pressure, and correcting the target air-fuel ratio, the output characteristics of the engine at the time of acceleration or deceleration can be simply changed to the target air-fuel ratio. From those set in accordance with the fuel ratio map, it can be changed to those required by the driver or those close to the driver's distance. Further, by detecting the engine speed from the phase of the crankshaft, the engine speed can be easily detected, and, for example, if the stroke state is detected from the phase of the crankshaft instead of the cam sensor, An expensive and large cam sensor can be eliminated.

FIG. 7 is a three-dimensional map for setting the fuel injection time from the conventional throttle opening and engine speed. The fuel injection time may be replaced with the fuel injection amount in consideration of the flow characteristics of the injector, but the output or torque characteristics of the engine cannot be estimated from the fuel injection amount alone. For this reason, in this map, for example, at a certain throttle opening and engine speed, the amount of fuel injection to be obtained and the amount of engine output or torque generated are measured, and the output required by the value is measured. The fuel injection amount is set so as to match the characteristics. Since the setting of the fuel injection amount is performed over all the intersections of the grid in a remarkable case, a great deal of labor and time are required. Moreover, even for similar engine types, if the required output characteristics are different, it is necessary to prepare all the maps for each engine. In other words, it can be said that the parameters constituting the map are numerical values whose physical meaning is difficult to grasp. Of course, when using this map, a throttle sensor such as a throttle opening sensor is required.

In the above embodiment, the in-pipe injection type engine has been described in detail, but the engine control device of the present invention can be similarly applied to a direct injection type engine. However, in a direct injection engine, since fuel does not adhere to the intake pipe, it is not necessary to consider this, and the calculation of the air-fuel ratio may be performed by substituting the total amount of injected fuel. In the above-described embodiment, a so-called multi-cylinder engine having four cylinders has been described in detail. However, the engine control device of the present invention can be similarly applied to a single-cylinder engine.

The engine control unit is
Various arithmetic circuits can be used in place of the microcomputer.

[0023]

As described above, according to the engine control apparatus of the first aspect of the present invention, the intake air amount is calculated from the intake pipe pressure and the operating state of the engine according to the intake air amount map stored in advance. And calculates the target air-fuel ratio from the intake pipe pressure and the operating state of the engine according to a target air-fuel ratio map stored in advance, for example, by dividing the intake air amount by the target air-fuel ratio to obtain the fuel injection amount. Can be calculated, the control is easy and accurate, and the intake air amount map is easy to measure and the target air-fuel ratio map is easy to set, so that the map creation is easy. Further, a throttle sensor such as a throttle opening sensor and a throttle position sensor for detecting an engine load is not required.

Further, according to the engine control device of the present invention, since it is configured to detect the transition period from the intake pipe pressure and to correct the target air-fuel ratio, the engine control device can be used during acceleration or deceleration. The output characteristics of the engine can be changed from those simply set in accordance with the target air-fuel ratio map to those required by the driver or closer to the interval between the drivers.

According to the engine control device of the present invention, since the engine speed is detected from the phase of the crankshaft, the engine speed can be easily detected. For example, if the stroke state is detected from the phase of the crankshaft instead of the cam sensor, an expensive and large-scale cam sensor can be eliminated.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an engine for a motorcycle and a control device thereof.

FIG. 2 is a block diagram showing an embodiment of an engine control device of the present invention.

FIG. 3 is an explanatory diagram for detecting a stroke state from a phase of a crankshaft and an intake pipe pressure.

FIG. 4 is a map for calculating a cylinder air mass stored in a cylinder air mass calculation unit.

FIG. 5 is a map for calculating a target air-fuel ratio stored in a target air-fuel ratio calculation unit.

FIG. 6 is a diagram illustrating the operation of a transition period correction unit.

FIG. 7 is a map for calculating a conventional fuel injection time.

[Explanation of symbols]

1 is an engine 3 is a crankshaft 4 is a piston 5 is a combustion chamber 6 is an intake pipe 7 is an intake valve 8 is an exhaust pipe 9 is an exhaust valve 10 is a spark plug 11 is an ignition coil 12 is a throttle valve 13 is an injector 15 is an engine control unit 20 is a crank angle sensor 21 is a cooling water temperature sensor 24 is an intake pipe pressure sensor 25 is an intake temperature sensor 26 is an engine speed calculating unit (operating state detecting unit, engine speed detecting unit) 27 is a crank timing detecting unit 28 is a cylinder Internal air mass calculation unit (intake air amount calculation means) 29 is a transition period correction unit (transition period correction unit) 31 is an ignition timing calculation unit 33 is a target air-fuel ratio calculation unit (target air-fuel ratio calculation unit) 34 is a fuel injection amount calculation Part (fuel injection amount calculation means)

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 3G084 BA11 BA13 BA14 BA15 BA16 DA13 EB09 EC02 EC03 FA02 FA11 FA20 FA26 FA33 FA38 3G301 HA01 JA20 LB01 LB07 MA01 MA11 MA13 NC04 ND01 PA07Z PD01Z PE01Z PE03Z PE08Z

Claims (3)

[Claims] 1. An intake pipe pressure detecting means for detecting an intake pipe pressure in an intake pipe of an engine, an operating state detecting means for detecting an operating state of the engine, and an intake pipe pressure detected by the intake pipe pressure detecting means. Intake air amount calculating means for calculating an intake air amount from an engine operating state detected by the operating state detecting means according to a previously stored intake air amount map, and an intake pipe pressure detected by the intake pipe pressure detecting means Target air-fuel ratio calculating means for calculating a target air-fuel ratio from the operating state of the engine detected by the operating state detecting means according to a target air-fuel ratio map stored in advance, and intake air calculated by the intake air amount calculating means. Fuel injection amount calculating means for calculating a fuel injection amount to be injected from the fuel injection device based on the amount and the target air-fuel ratio calculated by the target air-fuel ratio calculating means. Engine control device to be featured. 2. The target air-fuel ratio calculation means includes a transition period correction means for detecting a transition period from the intake pipe pressure detected by the intake pipe pressure detection means and correcting the target air-fuel ratio. The engine control device according to claim 1, wherein: 3. An engine speed detecting device according to claim 1, wherein said operating condition detecting device includes an engine speed detecting device for detecting an engine speed from a phase of a crankshaft.
An engine control device according to item 1.