JP2001065434A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the stability of idling speed by reducing the dispersion of the flow rate of a bypass air introduced in each cylinder, in an independent suction engine. SOLUTION: In this control device, two bypass air passages 33 are connected in a line to an air box 13 provided on the upper streamside of the suction manifold 12 of each cylinder of an independent suction engine and on the way of each bypass air passage 33, a bypass air control valve 34 of a duty control type for controlling the bypass air flow rate is provided. A volume room 35 for restraining the pressure change of the bypass air is provided on the down streamside of two bypass air passages 33 and the bypass air passed the bypass air control valve 34 is once streamed in the volume room 35 and the bypass air is separatingly streamed from this volume room 35 to the bypass air introduction passage 36 of each cylinder and introduced to the lower streamside of the throttle valve 15 of each cylinder. A check valve 37 is provided in the bypass air introduction passage 36 of each cylinder and it is prevented that the suction pressure pulse of each cylinder is interfered with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an independent intake type internal combustion engine in which a throttle valve is arranged for each intake passage of each cylinder to control an idle flow rate by controlling a bypass air flow rate bypassing the throttle valve. And a control device for an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, some motorcycles employ an independent intake engine provided with a throttle valve for each intake manifold of each cylinder. Also in this independent intake engine, the idle speed control is of a bypass air type that controls a bypass air flow rate that bypasses a throttle valve, and a throttle that controls a fully closed position of the throttle valve (throttle opening when the accelerator is off). There is a valve direct drive type, but the independent intake engine,
Since a throttle valve is provided for each cylinder, the use of a throttle valve direct-acting system requires a throttle control system for each cylinder, resulting in a very complicated system configuration and high cost. . Therefore,
In an independent intake engine, the bypass air system is more advantageous in terms of cost.

[0003]

When a bypass air system is adopted in an independent intake engine, a bypass air control valve may be provided in each of the bypass air passages of each cylinder.
In order to simplify the system configuration, a common bypass air control valve is provided upstream of the bypass air passage of each cylinder,
A configuration has been proposed in which bypass air is diverted from a common bypass air control valve to a bypass air passage of each cylinder.

However, in this configuration, the intake pressure pulsations of the respective cylinders interfere with each other through the bypass air passages of the respective cylinders, and as a result, the bypass air flow rate of the respective cylinders fluctuates, and the idle speed becomes unstable. Disadvantage.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and accordingly, it is an object of the present invention to reduce the variation in the bypass air flow rate of each cylinder and stabilize the idle speed in an independent intake type internal combustion engine. An object of the present invention is to provide a control device for an internal combustion engine that can improve the performance.

[0006]

According to a first aspect of the present invention, there is provided a control apparatus for an internal combustion engine, comprising: a volume chamber for suppressing a pressure fluctuation of bypass air downstream of a bypass air control valve. And a bypass air introduction passage for introducing bypass air from the volume chamber downstream of the throttle valve of each cylinder, and a check valve provided in each of the bypass air introduction passages of each cylinder. In this configuration, the bypass air that has passed through the bypass air control valve once flows into the volume chamber, flows from the volume chamber into the bypass air introduction passage of each cylinder, passes through the check valve, and passes through the check valve. Introduced downstream of the valve.

In the present invention, since the check valve is provided in each of the bypass air introduction passages of the respective cylinders, the check valve prevents the reverse flow of the bypass air due to the pulsation of the intake pressure of each of the cylinders. The intake pressure pulsation of each cylinder is prevented from interfering with each other through the introduction passage. Moreover, since the volume chamber is provided on the downstream side of the bypass air control valve, the pressure fluctuation of the bypass air in the volume chamber is effectively suppressed in combination with the bypass air backflow prevention effect by the check valve, The pressure of the bypass air in the volume chamber is stabilized. As a result, the variation in the flow rate of the bypass air introduced from the volume chamber to the downstream side of the throttle valve of each cylinder is reduced, and the idle speed is stabilized.

In this case, if the volume of the volume chamber is small, the effect of suppressing the pressure fluctuation in the volume chamber is reduced, so that the volume of the volume chamber is reduced by the intake passage downstream of the throttle valve per cylinder. It is preferable that the volume is set to be approximately equal to or larger than the volume or the cylinder volume per cylinder. In this way, it is possible to secure a sufficient volume in the volume chamber to absorb the influence of the variation in the amount of bypass air introduced due to the variation in the intake pressure of each cylinder, and to achieve a sufficient pressure fluctuation suppression effect by the volume chamber. Obtainable.

The bypass air control valve may be of a motor-driven type that controls the flow rate of the bypass air by changing the opening of the valve body with a stepping motor or the like. It is preferable to use a duty control type solenoid valve that controls the bypass air flow rate according to the time ratio of valve opening / closing. The duty control type bypass air control valve is inexpensive compared to the motor drive type, and can satisfy the demand for cost reduction.

When a bypass air control valve of the duty control type is used, the amount of air sucked into the volume chamber through the bypass air control valve varies with the opening / closing of the bypass air control valve. If there is no volume chamber downstream of the valve, the bypass air flow introduced into each cylinder fluctuates with the opening / closing of the bypass air control valve, and the idle speed becomes unstable. Since the volume chamber is provided on the downstream side of the bypass air control valve, pressure fluctuation of bypass air due to opening / closing of the bypass air control valve can be suppressed in the volume chamber, and the bypass introduced into each cylinder can be suppressed. The air flow rate can be stabilized.

During deceleration or racing when the throttle valve is fully closed, the intake negative pressure of each cylinder increases, the amount of air introduced into each cylinder from the volume chamber increases, and the pressure of bypass air in the volume chamber increases. Claim 4 because it tends to decrease.
As described above, it is preferable to control the bypass air control valve so that the flow rate of the bypass air flowing into the volume chamber becomes equal to or more than a predetermined amount during the deceleration of the throttle valve fully closed, during the racing, or for a predetermined period after the racing. By doing so, it is possible to suppress a pressure drop in the volume chamber (decrease in air volume in the volume chamber) due to deceleration of the throttle valve fully closed or racing, and thereafter, when the engine shifts to the idling operation, a sufficient amount of gas is immediately supplied to each cylinder. The bypass air flow rate of the amount can be introduced, and the idle speed can be quickly stabilized.

Further, in a configuration in which an intake passage for each cylinder is provided from an air box in which an air cleaner is stored, the volume chamber may be disposed in the air box. This eliminates the need to install the volume chamber outside, so that the entire system can be made compact and the appearance can be improved.

Further, a plurality of bypass air passages for introducing bypass air into the volume chamber may be provided in parallel, and a bypass air control valve may be provided in each of the bypass air passages. With this configuration, the adjustment range of the bypass air flow rate can be expanded by the plurality of bypass air control valves, and the idle speed control performance can be improved.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment (1)] An embodiment (1) in which the present invention is applied to a four-cylinder engine of a motorcycle will be described below with reference to FIGS.

First, the configuration of the entire engine control system will be described with reference to FIG. Engine 11 which is an internal combustion engine
An intake manifold 12 (intake passage) is connected to each intake port 10 of each cylinder, and an air box 13 is connected upstream of the intake manifold 12 of each cylinder.
The air sucked into the air box 13 is passed through an air cleaner (not shown) to the intake manifold 12 of each cylinder.
Sucked into. The air box 13 is provided with an intake air temperature sensor 14 for detecting an intake air temperature.

A throttle valve 15 is attached in the middle of the intake manifold 12 of each cylinder, and the opening of the throttle valve 15 (throttle opening) is detected by a throttle opening sensor 16. Further, an intake pressure sensor 17 for detecting intake pressure is provided downstream of the throttle valve 15 in the intake manifold 12, and a fuel injection valve 18 is provided near the intake port 10 of each cylinder.
Is attached.

On the other hand, the fuel pump 2
The fuel pumped at 0 is sent to the fuel pipe 21 → the fuel filter 22 → the fuel pipe 23 → the delivery pipe 24,
The fuel is distributed to the fuel injection valves 18 of each cylinder. Excess fuel in the delivery pipe 24 is returned to the fuel tank 19 through a path from the pressure regulator 25 to the return pipe 26.
The pressure regulator 25 adjusts the fuel pressure in the delivery pipe 24 so that the pressure difference between the fuel pressure in the delivery pipe 24 and the intake pressure becomes constant.

An ignition plug 27 is attached to the cylinder head of the engine 11 for each cylinder, and a high voltage generated on the secondary side of the ignition coil 28 is applied to the ignition plug 27 of each cylinder at each ignition timing to ignite. You. The engine 11 includes an engine speed sensor 29 for detecting an engine speed, and a cylinder discrimination sensor 30 for discriminating a specific cylinder.
And a water temperature sensor 31 for detecting a cooling water temperature. An atmospheric pressure sensor 32 for detecting the atmospheric pressure is attached to a predetermined position of the vehicle body.

Further, as shown in FIG.
3 are two bypass air passages 3 for bypassing a part of the intake air downstream of each throttle valve 15.
3 are connected in parallel, and in the middle of each bypass air passage 33, a bypass air control valve 3 for controlling a bypass air flow rate is provided.
4 are provided. Each bypass air control valve 34 is constituted by a duty control type solenoid valve, and controls an idle flow rate by controlling a bypass air flow rate by a valve opening / closing time ratio (duty ratio DU). These two bypass air control valves 34 are connected to an engine control circuit 39 described later.
, For example, at 180 ° C. alternately.

Each of the bypass air passages 33 is connected to a volume chamber 35 for suppressing a pressure fluctuation of the bypass air. In the volume chamber 35, the bypass air flowing into the volume chamber 35 is supplied to the throttle chamber of the intake manifold 12 of each cylinder. Four bypass air introduction passages 36 to be introduced downstream of the valve 15 are connected. Therefore, the bypass air that has passed through the bypass air control valve 34 once flows into the volume chamber 35, flows from the volume chamber 35 into the bypass air introduction passages 36 of each cylinder, and flows downstream of the throttle valve 15 of each cylinder. Introduced on the side.

In order to obtain a sufficient pressure fluctuation suppressing effect, the volume chamber 35 has a volume substantially equal to or larger than the volume of the intake passage downstream of the throttle valve 15 per cylinder or the volume of cylinder per cylinder. It is formed so that it becomes. Further, a check valve 37 is provided in the bypass air introduction passage 36 of each cylinder, and the reverse flow of bypass air due to the intake pressure pulsation of each cylinder is blocked by the check valve 37. To prevent the intake pressure pulsations of the cylinders from interfering with each other.

On the other hand, output signals of various sensors such as the throttle opening sensor 16 and the engine speed sensor 29 are input to the engine control circuit 39. This engine control circuit 3
Reference numeral 9 is mainly composed of a microcomputer.
The duty ratio calculation routine of FIG. 3 and the energization time calculation routine of FIG. 4 stored in M40 (storage medium) are executed to make the idle speed equal to the target idle speed. Control. Hereinafter, the processing content of each routine will be described.

The duty ratio calculation routine of FIG. 3 is executed every predetermined time (for example, every 100 ms). When the process of this routine is started, first, at step 101, it is determined whether or not an idle speed feedback control condition is satisfied. Here, the idle speed feedback control conditions include, for example, that a predetermined time has elapsed after the start, that the throttle valve 15 is fully closed, that the engine speed is equal to or lower than the predetermined speed, that an abnormality in each sensor has occurred. There is no such thing. If all of these conditions are satisfied, the idle speed feedback control condition is satisfied. However, if any one condition is not satisfied, the idle speed feedback control condition is not satisfied. If the idle speed feedback control condition is satisfied, the routine proceeds to step 102, where it is determined whether a predetermined time has elapsed since the idle speed feedback control condition was satisfied.

If the idle speed feedback control condition is not satisfied or if a predetermined time has not elapsed after the idle speed feedback control condition is satisfied, the routine proceeds to step 103, where it is determined whether or not the throttle valve 15 is fully closed. I do. If the throttle valve 15 is fully closed, the routine proceeds to step 104, where it is determined whether or not the engine speed NE is higher than a predetermined speed E.

If the throttle valve is fully closed and the engine rotational speed NE is higher than the predetermined rotational speed E, it is determined that the throttle valve is fully closed and deceleration is being performed, and the routine proceeds to step 105.
The duty ratio DU of the bypass air control valve 34 is set to a predetermined value F
Set to. Here, the predetermined value F is equal to or larger than the predetermined amount of the bypass air flow rate flowing into the volume chamber 35 during the deceleration of the throttle valve fully closed, that is, the pressure decrease in the volume chamber 35 (the decrease in the air amount in the volume chamber 35). The duty ratio is set such that the flow rate of the bypass air required to suppress the air flow can be secured.

On the other hand, if the throttle valve 15 is not fully closed or the engine speed NE is equal to or lower than the predetermined engine speed E, the routine proceeds to step 106, where the duty ratio DU of the bypass air control valve 34 is changed according to the cooling water temperature. Calculated by a map or a mathematical formula. The duty ratio DU according to the cooling water temperature is set to a duty ratio that can maintain the engine speed NE at a target idle speed NET described later.

On the other hand, if it is determined in step 102 that the predetermined time has passed since the idle speed feedback control condition was satisfied, the process proceeds to step 107,
The target idle speed NET corresponding to the cooling water temperature or the like is calculated by a map or a mathematical formula, and in the next step 108, the speed difference DLNE between the current engine speed NE and the target idle speed NET is calculated by the following formula. DLNE = NE-NET

Thereafter, the duty ratio DU of the bypass air control valve 34 is calculated as follows. First, in step 109, it is determined whether or not the rotational speed deviation DLNE is smaller than -A. If it is smaller than -A (that is, if the current engine rotational speed NE is lower than NET-A), step 111 is executed. The duty ratio DU is increased by a predetermined amount C from the previous value in order to increase the engine speed NE. On the other hand, if the rotational speed deviation DLNE is equal to or greater than -A, the process proceeds to step 110, where it is determined whether the rotational speed deviation DLNE is greater than B. If the rotational speed deviation DLNE is greater than B (that is, if the current engine rotational speed NE is NET + B If the duty ratio DU is lower than the previous value, the routine proceeds to step 112, where the duty ratio DU is reduced by a predetermined amount D from the previous value in order to reduce the engine speed NE.

When -A≤DLNE≤B, the current engine speed NE is stable around the target idle speed NET, and therefore the previous duty ratio DU is maintained. Thereafter, in step 113, upper and lower limits of the duty ratio DU are checked, and the set value of the duty ratio DU is set within a range of, for example, 0% ≦ DU ≦ 100%. Thus, the current duty ratio DU is set.

The energizing time calculation routine shown in FIG. 4 is started by an interrupt signal generated based on the output signal of the engine speed sensor 29. In step 201, the energizing time TON of the bypass air control valve 34 is updated to the latest T36.
0 (the time required to rotate at 360 ° C. A), the duty ratio DU of the bypass air control valve 34, and the invalid control time TIS
It is calculated by the following equation using C. TON = T360 ・ DU + TISC Here, the invalid control time TISC is a time set in accordance with the operation response delay of the bypass air control valve 34. In this case, as the duty ratio DU increases, the energization time TON (valve opening time) increases and the bypass air flow rate increases.

The engine control circuit 39 uses the duty ratio DU calculated in the duty ratio calculation routine of FIG. 3 and the power supply time TON calculated in the power supply time calculation routine of FIG.
The two bypass air control valves 34 are alternately driven at every 180 ° C. A (see FIG. 5), and the idle speed is set to the target idle speed N while the idle speed feedback control condition is satisfied.
Feedback control is performed on the bypass air flow rate (duty ratio DU) so as to match ET.

The effect (see FIG. 7) of the idle speed control device of the embodiment (1) described above will be described in comparison with a conventional idle control device (see FIG. 6). The conventional bypass air type idle speed control system includes a volume chamber 3
5 and the check valve 37, there is no need to use a duty control type bypass air control valve.
Due to the fluctuation of the bypass air flow rate due to the valve closing and the mutual interference of the intake pressure pulsation of each cylinder, the pressure fluctuation in the bypass passage increases as shown in FIG. In addition, the pressure fluctuation width also differs for each cylinder due to variations in the pipe diameter and port diameter of each bypass passage. As a result, the pressure difference (shaded area) between the intake pressure of each cylinder and the pressure in the bypass passage becomes uneven between the cylinders, and the flow rate of the bypass air introduced into each cylinder becomes large between the cylinders due to this pressure difference. As a result, the idle speed becomes unstable.

On the other hand, in the idle speed control system of this embodiment (1), since the volume chamber 35 is provided on the downstream side of the bypass air control valve 34, the duty control type bypass air control valve 34 is provided. Even if used, the pressure fluctuation of the bypass air due to the opening / closing of the bypass air control valve 34 is suppressed in the volume chamber 35. Further, since the check valve 37 is provided in each of the bypass air introduction passages 36 of the respective cylinders, the backflow of the bypass air due to the intake pressure pulsation of each cylinder is blocked by the check valve 37, and the bypass air introduction passage 3 of each of the cylinders is blocked.
6 prevents the intake pressure pulsation of each cylinder from interfering with each other. As a result, the synergistic effect of the pressure fluctuation suppression effect of the volume chamber 35 itself and the bypass air backflow prevention effect of the check valve 37 as shown in FIG.
Fluctuations in the internal pressure are effectively suppressed, and the pressure in the volume chamber 35 is stabilized. As a result, the differential pressure (the shaded portion) between the intake pressure of each cylinder and the pressure in the volume chamber 35 is substantially averaged in each cylinder pipe, and the differential pressure causes the bypass air introduced into each cylinder from the volume chamber 35 to each cylinder. Variations in the flow rate are reduced, and the idle speed is stabilized.

In addition, the duty control type bypass air control valve 34 is inexpensive as compared with the motor drive type, so that the requirement for cost reduction can be satisfied. However, the bypass air control valve 34 may be of a motor-driven type that controls the flow rate of the bypass air by changing the opening of the valve body with a stepping motor or the like.

When the volume of the volume chamber 35 is small, the effect of suppressing the pressure fluctuation in the volume chamber 35 is small. However, in this embodiment (1), the volume of the volume chamber 35 is reduced by the throttle valve 15 per cylinder. Since it is set to be substantially equal to or larger than the downstream intake passage volume or the cylinder volume per cylinder, the influence of the fluctuation of the intake pressure of each cylinder and the fluctuation of the bypass air introduction amount by the bypass air control valve 34. Can be secured in the volume chamber 35 and a sufficient pressure fluctuation suppression effect by the volume chamber 35 can be obtained.

When the throttle valve is fully closed, the negative pressure of intake air in each cylinder increases, the amount of air introduced into each cylinder from the volume chamber 35 increases, and the pressure in the volume chamber 35 tends to decrease. In consideration of the above, in the embodiment (1), when the throttle valve is fully closed, the duty ratio DU of the bypass air control valve 34 is set to the predetermined value F, and the bypass flowing into the volume chamber 35 is set. Since the air flow rate is controlled to a predetermined amount or more to secure a bypass air flow rate necessary for suppressing a pressure drop in the volume chamber 35 (a decrease in the air volume in the volume chamber 35), the throttle valve is fully closed. A pressure drop in the volume chamber 35 (a decrease in the amount of air in the volume chamber 35) due to the deceleration can be suppressed, and a sufficient amount of bypass air flow is immediately introduced into each cylinder when shifting from the deceleration state to the idle operation. Bets can be, the idle speed can be quickly stabilized.

During racing, the amount of air introduced into each cylinder from the volume chamber 35 tends to increase and the pressure in the volume chamber 35 tends to decrease. As in the case of deceleration when the valve is fully closed, the duty ratio DU of the bypass air control valve 34 is set to a predetermined value, and the flow rate of bypass air flowing into the volume chamber 35 is controlled to a predetermined amount or more. A bypass air flow rate necessary for suppressing a pressure decrease (a decrease in the amount of air in the volume chamber 35) may be ensured.

Further, in this embodiment (1), the volume chamber 35
Two bypass air passages 33 for introducing bypass air into
Since the bypass air flow control valve 34 is provided in each of the bypass air passages 33 in parallel with each other, the adjustment range of the bypass air flow rate can be expanded by the two bypass air control valves 34, and the idle speed control performance is improved. Can be increased.

However, if one bypass air control valve 34 can sufficiently adjust the bypass air flow rate,
One bypass air passage 33 may be provided with one bypass air control valve 34 in the bypass air passage 33. Alternatively, three or more bypass air passages 33,
The bypass air control valves 34 may be provided in each of the bypass air passages 33 in parallel.

[Embodiment (2)] In the embodiment (1), the bypass air passage 33, the bypass air control valve 34, and the volume chamber 35 are arranged outside the air box 13.
In the embodiment (2) of the present invention, as shown in FIG. 8, the bypass air passage 33, the bypass air control valve 34 and the volume chamber 35 are arranged inside the air box 13. With this configuration, it is not necessary to install the bypass air control valve 34 and the volume chamber 35 outside, so that the entire system can be made compact and the appearance can be improved. Note that only the volume chamber 35 may be installed in the air box 13 and the bypass air control valve 34 may be installed outside the air box 13.

In each of the embodiments described above, the present invention
Although the present invention is applied to a cylinder engine, the present invention may be applied to an engine having a number of cylinders other than four.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an entire engine control system showing an embodiment (1) of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a bypass air passage system;

FIG. 3 is a flowchart showing the flow of processing of a duty ratio calculation routine.

FIG. 4 is a flowchart showing a flow of a power-on time calculation routine;

FIG. 5 is a time chart for explaining a driving method of two bypass air control valves.

FIG. 6 is a time chart showing the behavior of the pressure in the bypass passage in the conventional idle speed control system.

FIG. 7 is a time chart showing the behavior of the pressure in the volume chamber in the idle speed control system of the embodiment (1).

FIG. 8 is a schematic configuration diagram of an entire engine control system showing an embodiment (2) of the present invention.

[Explanation of symbols]

11 engine (internal combustion engine), 12 intake manifold (intake passage), 13 air box, 15 throttle valve, 16 throttle opening sensor, 29 engine speed sensor, 33 bypass air passage, 34 bypass Pneumatic control valve, 35 volume chamber, 36 bypass air introduction passage, 37 check valve, 39 engine control circuit.

Claims (6)

[Claims] 1. A control device for an internal combustion engine, wherein a throttle valve is provided for each intake passage of each cylinder, and a bypass air control valve controls a flow rate of a bypass air bypassing the throttle valve to control an idle speed. On the downstream side of the air control valve, a volume chamber for suppressing pressure fluctuation of bypass air, and a bypass air introduction passage for introducing bypass air from the volume chamber to the downstream side of the throttle valve of each cylinder are provided. A control device for an internal combustion engine, wherein a check valve is provided in each of the air introduction passages. 2. The capacity of the volume chamber is set to be substantially equal to or larger than the capacity of an intake passage downstream of a throttle valve per cylinder or the capacity of a cylinder per cylinder. 3. The control device for an internal combustion engine according to claim 1. 3. The internal combustion engine according to claim 1, wherein the bypass air control valve is a duty control type solenoid valve that controls a bypass air flow rate based on a valve opening / closing time ratio. Control device. 4. The bypass air control valve is controlled such that a flow rate of bypass air flowing into the volume chamber is equal to or more than a predetermined amount during deceleration of the throttle valve fully closed, during racing, or during a predetermined period after racing. The control device for an internal combustion engine according to any one of claims 1 to 3, wherein 5. The air intake passage of each cylinder is provided to be branched from an air box containing an air cleaner, and the volume chamber is disposed in the air box. The control device for an internal combustion engine according to any one of the above. 6. The bypass air passage for introducing bypass air into the volume chamber is provided in parallel, and the bypass air control valve is provided in each of the bypass air passages. 6. The control device for an internal combustion engine according to any one of 5.