JP2519726B2 - Ignition timing control device for dual intake engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a dual intake system that controls the ignition timing of an engine provided with a sub-throttle valve that throttles a portion of the intake passage downstream of the main throttle valve. The present invention relates to an ignition timing control device for an engine.

(Prior Art) The ignition timing of an engine is represented by an ignition advance value that is a value of a crank angle before top dead center, and this ignition advance value is an engine operating state, for example, an engine such as intake negative pressure. The ignition timing is controlled by changing it according to the load and the engine speed. In that case, the ignition advance value increases as the engine load increases,
The higher the engine speed, the larger the value set.

Such ignition timing control is usually performed by a negative pressure type automatic advance mechanism, which is incorporated in a distributor and takes an operating state according to the negative pressure of the intake air.
As disclosed in Japanese Patent Publication No. JP-A-2003-264, it is automatically performed by a centrifugal automatic advance mechanism that operates in accordance with the engine speed. In recent years, this is done electronically using a microcomputer or the like. It has also been put into practical use to perform it by a control device.

On the other hand, for the main purpose of improving the combustibility of the air-fuel mixture when the engine is in a low-load operating state, for example, as shown in Japanese Patent Laid-Open No. There has been proposed a dual intake engine in which an auxiliary throttle valve is disposed in the side portion and the intake passage is throttled by the auxiliary throttle valve when the engine is in a low load operation state. In such a dual intake engine, since the intake passage is throttled by the sub-throttle valve during low load operation, the flow velocity of the intake air flowing in the downstream side of the sub-throttle valve is increased and swirl of air-fuel mixture is generated in the combustion chamber. As a result, the combustibility is improved and the fuel efficiency is improved.

(Problems to be Solved by the Invention) In the dual intake engine as described above, even when the engine load and the engine speed are the same, when the auxiliary throttle valve is in the closed state, it is opened. The flow velocity of the air-fuel mixture in the combustion chamber becomes higher than that at a certain time, and the swirl of the air-fuel mixture generated there becomes stronger. Therefore, if the ignition timing when the sub-throttle valve is in the closed state is set in accordance with the ignition timing required when the sub-throttle valve is in the open state, the ignition timing is excessively advanced. There is a risk that it will end up. In that case, as the engine speed increases, the amount of intake air increases and the swirl generated in the combustion chamber becomes stronger.Therefore, the ignition timing when the sub-throttle valve is closed is when the auxiliary throttle valve is open. It is necessary to correct the ignition timing to the lag side at a higher rate as the engine speed becomes higher than the required ignition timing. However, in the conventional art, such a point is not taken into consideration when setting the ignition timing, and the ignition device is operated with the same ignition timing as when the sub-throttle valve is in the open state even when it is in the open state. Therefore, with the sub-throttle valve closed,
When the engine speed is relatively high, problems such as high combustion noise and knocking may occur.

In view of such a point, the present invention ignites the air-fuel mixture with an appropriate ignition timing regardless of whether the auxiliary throttle valve that throttles the portion of the intake passage on the downstream side of the main throttle valve is in the open state or the closed state. It is an object of the present invention to provide an ignition timing control device for a dual intake engine capable of performing the above.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the ignition timing control device for a double intake engine according to the present invention has a main structure in the intake passage of the engine as shown in the basic configuration thereof in FIG. An open / closed state detecting means arranged downstream of the throttle valve for detecting the open / closed state of the sub-throttle valve which closes the intake passage when the engine is in a low-load operating state and narrows the intake passage. The first ignition timing setting means for setting the ignition timing of No. 1 and the first ignition timing when the operating state of the engine is the same when the auxiliary throttle valve is in the open state and when it is in the closed state. Second ignition timing setting means for setting a second ignition timing different from the first ignition timing set by the timing setting means, and opening / closing state detecting means detect that the auxiliary throttle valve is in an open state. When the open state is detected, the first ignition timing setting means sets the first ignition timing, and when the open / close state detecting means detects that the auxiliary throttle valve is closed, the second ignition timing setting is set. Ignition timing control means for activating the ignition device attached to the engine at the first ignition timing set by the means,
Under the same engine operating condition, the second ignition timing setting means has a smaller rate of change with respect to a change in the engine speed than the first ignition timing set by the first ignition timing setting means. The second ignition timing is set as follows.

(Operation) In the ignition timing control device for a dual intake engine according to the present invention having the above-described configuration, the second ignition timing setting means causes the second ignition timing setting means to operate when the auxiliary throttle valve is closed.
When the sub-throttle valve is in the open state, the second ignition timing in which the change rate with respect to the change in the engine speed is smaller than the first ignition timing set by the first ignition timing setting means is Is set.

Therefore, when the sub-throttle valve is in the open state and the closed state, ignition is performed at an ignition timing that matches the combustion speed of the air-fuel mixture in the combustion chamber, and combustion noise and knocking can be reduced. Fuel efficiency can be improved.

(Example) Hereinafter, the Example of this invention is described with reference to drawings.

FIG. 2 shows an example of an ignition timing control device for a dual intake engine according to the present invention, together with the main parts of the engine to which the ignition timing control device is applied.

In FIG. 2, a cylinder 14 is provided in an engine body 10 composed of a cylinder head 11 and a cylinder block 13, and a piston 16 is fitted and inserted in the cylinder 14.
Intake passage 20 and exhaust passage via intake valve 18 and exhaust valve 19
22 are connected respectively. A combustion chamber 24 is formed in the cylinder 14 by being surrounded by the cylinder head 11, the cylinder block 13, the piston 16, the intake valve 18, the exhaust valve 19, etc., and the ignition plug 26 is provided in the combustion chamber 24. There is.

In the intake passage 20, from the upstream side thereof, an carburetor in which an air cleaner 28 for sequentially purifying intake air and a main throttle valve 32 for opening and closing the intake passage 20 in conjunction with an accelerator pedal are arranged.
An intake negative pressure sensor 35 for detecting an intake negative pressure in a portion of the intake passage 20 downstream of the main throttle valve 32 is provided. The most downstream portion of the intake passage 20 is a partition wall 17
Is divided into a primary side passage portion 21 and a secondary side passage portion 23. The cross-sectional area of the primary passage 21 is smaller than that of the secondary passage 23, and the most downstream end of the primary passage 21 has a combustion chamber 24.
An opening is made in the circumferential direction of the combustion chamber 24 so that a swirl of the air-fuel mixture is generated therein. Further, the secondary side passage portion 23 has a diaphragm type actuator.
An auxiliary throttle valve 27 that is driven to open and close by 25 is provided.

The diaphragm type actuator 25 includes a negative pressure introducing chamber 25a via a conduit 29 from a surge tank 15 located between the main throttle valve 32 and the sub throttle valve 27 in the intake passage 20.
When the absolute value of the intake negative pressure introduced into the intake valve is greater than or equal to a predetermined value, the diaphragm rod 25b is retracted to close the auxiliary throttle valve 27, and when the absolute value of the intake negative pressure is less than the predetermined value, the diaphragm is closed. The rod 25b is projected to open the sub throttle valve 27. An on-off solenoid valve 34 is installed in the conduit 29 to shut off the intake negative pressure from the intake passage 20 to the negative pressure introducing chamber 25a. The open / close solenoid valve 34 is in an open state when an open / close control signal Ca is supplied from a control unit 100 described later, and the intake passage
20 and the negative pressure introducing chamber 25a are communicated with each other, the atmosphere introducing port 34a is closed, and when the supply of the opening / closing control signal Ca is stopped, the intake passage 20 and the negative pressure introducing chamber 25a are closed. At the same time, the atmosphere introducing port 34a is opened to introduce the atmospheric pressure into the negative pressure introducing chamber 25a.

Further, a known distributor 40 whose rotary shaft is rotationally driven by a crankshaft (not shown) is attached to the engine body 10, and the distributor 40 corresponds to the rotational speed and the rotational angle of the rotary shaft. Revolution sensor 36 to detect engine speed
Is provided.

Then, the timing at which the electrodes of the spark plug 26 are caused to discharge, that is, the ignition timing of the engine, is set by the centrifugal automatic advance mechanism 41 incorporated in the distributor 40 and the ignition advance value θ _A and the negative pressure type are set. The ignition advance value θ, which is the sum of the ignition advance value θ _B set by the automatic advance mechanism 42, is adjusted. Although only a part of the centrifugal automatic advance mechanism 41 is shown,
As is well known, when the engine is driven to rotate in conjunction with the engine, it does not operate when the engine speed does not reach a specified value, and when the engine speed rises above a specified value, the engine speed The ignition timing is advanced as the temperature rises. Therefore, the ignition advance value θ _A set by the centrifugal automatic advance mechanism 41 is, for example, as shown in FIG. 3, when the engine speed N is equal to or higher than a predetermined value N ₁ , The higher N is, the larger the value is.

Further, in the negative pressure introducing chamber 48a of the diaphragm type actuator 48 in the negative pressure automatic advance mechanism 42, a negative pressure supply conduit 46 for introducing an intake negative pressure in the vicinity of the main throttle valve 32 in the intake passage 20 is provided in three directions. It is connected via a solenoid valve 47. The three-way solenoid valve 47 energizes the built-in solenoid for a period corresponding to the pulse width of the drive pulse signal Cp supplied from the control unit 100, and brings the negative pressure supply conduit 46 into a communication state when the built-in solenoid is not energized. At the same time, the air port 47a is closed. Then, when intake negative pressure is introduced into the negative pressure introducing chamber 48a of the diaphragm actuator 48 through the negative pressure supply conduit 46, the central portion of the diaphragm 48b resists the elasticity of the return spring 51 and moves to the right in FIG. As a result, the advancer rod 52 is similarly pulled rightward, and the breaker plate 53 rotates in the direction opposite to the rotation direction of the cam shaft (not shown) (the direction of arrow Q in FIG. 2), It is designed to advance the ignition timing. on the other hand,
When the built-in solenoid of the three-way solenoid valve 47 is excited, the introduction of intake negative pressure into the negative pressure introduction chamber 48a is blocked, the atmosphere port 47a is opened, and the atmospheric pressure is introduced from the three-way solenoid valve 47. It is designed to be introduced into the room 48a. When the atmospheric pressure is supplied to the negative pressure introducing chamber 48a, the return spring 51 causes the diaphragm 48
b is returned to its original position and the ignition timing is not changed.

The open / close solenoid valve 34 and the three-way solenoid valve 47 described above.
A control unit 100 is provided in this example in order to control the operation. The control unit 100 includes a detection signal Sb corresponding to the intake negative pressure obtained from the intake negative pressure sensor 35 and an open / closed state of the sub throttle valve 27 obtained from an open / close detection sensor 31 arranged in association with the sub throttle valve 27. And a detection signal Sn representing the engine speed obtained from the engine speed sensor 36 and the like.

When the absolute value of the intake negative pressure represented by the detection signal Sb is greater than or equal to a predetermined value and the engine speed represented by the detection signal Sn is less than the predetermined value, the control unit 100, therefore, the engine, for example, the vertical axis. When the engine load L is taken on and the engine speed N is taken on the horizontal axis, as shown by region I in FIG.
When the open / close control signal Ca is supplied to the open / close solenoid valve 34 to open it, and when it is in a high load and high rotation state as indicated by region II in FIG. 4, the supply of the open / close control signal Ca is stopped to open / close the valve. Close the solenoid valve 34. As a result, when the engine is in the low load and low rotation state, the intake negative pressure is supplied to the negative pressure introducing chamber 25a of the diaphragm type actuator 25 through the conduit 29, and the auxiliary throttle valve 27 is closed. Therefore, in such a case, the air-fuel mixture is supplied to the combustion chamber 24 with its flow velocity increased only through the primary-side passage portion 21, and a swirl of the air-fuel mixture is generated in the combustion chamber 24 to improve its combustibility. Become. When the engine is in the high load and high rotation state, the sub throttle valve 27 is opened, and the air-fuel mixture is supplied to the combustion chamber 24 through both the secondary side passage portion 23 and the primary side passage portion 21. .

The control unit 100 controls the opening / closing of the sub throttle valve 27 as described above, and at the same time controls the ignition timing, the control value D that determines the pulse width of the drive pulse signal Cp is detected by the detection signal Sc. When it is detected that 27 is in the open state, it is set to the maximum value Dm, and the drive pulse signal Cp having the pulse width corresponding to the maximum value Dm is formed and supplied to the three-way solenoid valve 47.
As a result, when the sub throttle valve 27 is opened, a composite negative pressure B'according to the intake negative pressure B of the portion of the intake passage 20 where the main throttle valve 32 is arranged is provided in the negative pressure introducing chamber 48a. The diaphragm 48b is supplied, the diaphragm 48b is sucked according to the combined negative pressure B ', the advancer rod 52 is drawn in, and the ignition timing is advanced. In that case, the ignition advance value θ _B set by the negative pressure type automatic advance mechanism 42 with respect to the change of the intake negative pressure B is changed as shown in FIG. 5, for example.

On the other hand, the control unit 100 detects the detection signal S
When it is detected by c that the sub throttle valve 27 is closed, the control value D is set to the maximum value when the engine speed N is less than the predetermined value N ₁ , as shown in FIG. When Dm is set to a value N ₁ or more, it is set to a smaller value as the engine speed N increases, and a drive pulse signal Cp having a pulse width corresponding to the set control value D is formed. Is supplied to the three-way solenoid valve 47. Thereby, synthesis negative pressure B 'is supplied to the negative pressure introducing chamber 48a at the time of taking a certain value intake negative pressure B, for example, in as shown in FIG. 7, the engine speed N is a value N ₁ or more Under the condition of, the higher it is, the closer it becomes to the atmospheric pressure Po.

By doing so, when the sub-throttle valve 27 is in the closed state, the combined negative pressure B'supplied to the negative pressure introducing chamber 48a becomes smaller than when it is in the open state.
As a result, the ignition advance value θ _B set by the negative pressure automatic advance mechanism 42 is set when the auxiliary throttle valve 27 is closed even when the intake negative pressure B and the engine speed N are the same. It is smaller than when in the open state, and moreover,
As the engine speed N increases, the ignition advance value θ _B set when the sub-throttle valve 27 is in the closed state and the ignition advance value θ _B set when the sub-throttle valve 27 is in the open state.
The difference with _B is said to open.

Therefore, the ignition advance value θ that determines the ignition timing of the engine
Under the same intake negative pressure B, the solid line in FIG. 8 indicates that the sub throttle valve 27 is open, and the alternate long and short dash line indicates that the sub throttle valve 27 is closed. Will be as shown in each. That is, when the engine speed N exceeds the value N ₁ , the ignition advance value θ becomes smaller when the sub-throttle valve 27 is closed than when it is opened. As the engine speed N increases, the difference between θ in the open state and θ in the closed state becomes larger. Therefore, when the sub-throttle valve 27 is in the closed state, the change rate of the ignition timing with respect to the change in the engine speed is smaller than when the sub-throttle valve 27 is in the open state. Therefore, when the sub-throttle valve 27 is in the closed state, the ignition timing of the engine is corrected to the delay side with reference to the case in which the sub-throttle valve 27 is in the open state. The amount of correction to the delay side of the ignition timing is large.

In this example, the ignition signal Ig is supplied from the distributor 40 to the spark plug 26 at the timing corresponding to the ignition advance value θ set as described above, and the combustion chamber
Since the air-fuel mixture in 24 is ignited, the ignition timing becomes appropriate regardless of whether the sub-throttle valve 27 is open or closed. Therefore, the fuel efficiency is improved, and the combustion noise and knocking caused by the increase in the combustion speed of the air-fuel mixture when the sub-throttle valve 27 is closed are suppressed.

Control unit 100 that performs the control as described above
Is configured by using, for example, a microcomputer, and an example of a program for controlling the ignition timing executed by the microcomputer in such a case will be described with reference to the flowchart shown in FIG.

After the start, this program takes in the detection signals Sb, Sc and Sn in the process 101, and in the subsequent decision 102, judges whether the sub throttle valve 27 is in the closed state based on the detection signal Sc and judges whether the sub throttle valve 27 is closed. When it is determined that 27 is not in the closed state, the control value D is set to the maximum value Dm in the process 103, and the process proceeds to the process 105. If the decision 102 determines that the sub-throttle valve 27 is in the closed state, the control value D is set in the process 104 in a relationship corresponding to the engine speed N as shown in FIG. Proceed to process 105.

In the process 105, the drive pulse signal Cp having a pulse width according to the control value D set in the process 103 or the process 104 is formed, supplied to the three-way solenoid valve 47, and returned to the original state.

In the above example, the combined negative pressure B'supplied to the negative pressure introducing chamber 48a of the negative pressure automatic advance mechanism 42 is changed to set the ignition set when the sub throttle valve 27 is in the open state. Although the ignition timing on the side delayed from the timing is set to be the ignition timing when the sub-throttle valve 27 is in the closed state, the ignition timing control device for the dual intake engine according to the present invention is not limited thereto. Instead, for example, the characteristics of the governor weight or the like provided in the centrifugal automatic advance mechanism 41 can be changed in advance in two steps, and the characteristics are selected according to the opening / closing state of the sub throttle valve 27. Thus, the ignition timing when the sub throttle valve 27 is in the open state and the ignition timing when the sub throttle valve 27 is in the closed state may be set separately.

Further, in the above-mentioned example, the control of the ignition timing is performed by the centrifugal automatic advance mechanism 41 and the negative pressure automatic advance mechanism 42 additionally provided in the distributor 40. The ignition timing control device for the intake engine includes a centrifugal automatic advance mechanism 41 and a negative pressure automatic advance mechanism.
Instead of 42, the ignition timing may be controlled by an electronic control unit using a microcomputer.

(Effects of the Invention) As is clear from the above description, the ignition timing control device for a dual intake engine according to the present invention, when the auxiliary throttle valve is in the closed state, has the ignition timing set when it is in the open state. In comparison, the ignition timing is set so that the rate of change with respect to the change in engine speed is small, so that the combustion speed of the air-fuel mixture in the combustion chamber is different when the sub-throttle valve is open and closed. Ignition is performed at a matched ignition timing, whereby combustion noise and knocking can be suppressed, and fuel consumption can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of an ignition timing control device for a multiple intake engine according to the present invention in correspondence with the claims, and FIG. 2 is an example of an ignition timing control device for a multiple intake engine according to the present invention. FIG. 3 is a schematic diagram showing a dual engine to which it is applied, FIGS. 3 to 8 are characteristic diagrams used to explain the operation of the example shown in FIG. 2, and FIG. 9 is an example shown in FIG. 9 is a flowchart showing an example of a program executed by a microcomputer when the microcomputer is used as the control unit. In the figure, 10 is the engine body, 20 is the intake passage, 24 is the combustion chamber,
25 is a diaphragm type actuator, 26 is a spark plug,
27 is a sub throttle valve, 30 is a carburetor, 31 is an open / close detection sensor, 32 is a main throttle valve, 36 is a rotation speed sensor, 40 is a distributor, 41 is a centrifugal automatic advance mechanism, 42 is a negative pressure automatic advance mechanism , 47 is a three-way solenoid valve, 48 is a diaphragm type actuator, and 100 is a control unit.

Claims (1)

(57) [Claims] 1. An opening / closing state of a sub-throttle valve which is arranged in a portion of an intake passage of the engine downstream of a main throttle valve and which is closed when the engine is in a low load operation state to throttle the intake passage. The open / closed state detecting means for detecting, the first ignition timing setting means for setting the first ignition timing according to the operating state of the engine, and the first ignition timing setting means for the change rate with respect to the change of the engine speed. The second ignition timing which is smaller than the first ignition timing set by
Second ignition timing setting means for setting the ignition timing and the opening / closing state detecting means detects that the sub-throttle valve is in the open state, the first ignition timing setting means sets the first ignition timing setting means. 1 and the second ignition timing set by the second ignition timing setting means when the opening / closing state detecting means detects that the sub-throttle valve is in the closed state. An ignition timing control device for a dual intake engine, comprising: an ignition timing control means for operating an ignition device attached to the engine.