JPS61190131A - Engine control device - Google Patents

Abstract

PURPOSE:To prevent generation of knocking by providing an octane value detecting means of engine supply fuel and reducing charging amount of intake air as the octane value becomes less. CONSTITUTION:A specific gravity sensor 31 and a temperature sensor 37 etc. are provided on the fuel tank 30 of an engine, and specific gravity signal and temperature signal of fuel 36 are input to a controller 34. While, a valve timing adjusting actuator 28 is provided on an intake valve 10 and controlled by the controller 34. When the octane value obtained by calculating upon signals from the specific gravity sensor 31 and temperature sensor 37 is low, charging amount of intake air is reduced to prevent generation of knocking, by advancing the close timing of the intake valve 10 by means of the actuator 28.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an engine control device, and particularly to an engine control device that controls the intake air filling amount according to the octane number of fuel supplied to the engine. Regarding a control device.

(Prior Art and Problems to be Solved) It has been known for a long time that when the fuel supplied to an engine is switched from a high octane fuel to a low octane fuel, knocking occurs and the output decreases. In order to eliminate such inconveniences caused by using fuels with different octane numbers, it has been known to change engine operating conditions depending on the octane number of the fuel. For example, Japanese Patent Laid-Open No. 58-131360 discloses a control device that changes the ignition timing in accordance with the octane number of the supplied fuel. The present invention provides a device that prevents the above phenomenon from occurring and allows fuels with different octane numbers to be applied to the engine without any trouble by using new means other than the disclosed device.

(Means for Solving the Problems) The engine control device of the present invention includes a means for detecting the octane number of the fuel supplied to the engine, and a signal from the octane number detecting means when the octane number of the supplied fuel is low and when the octane number is high. Compared to the above, the present invention is characterized in that it includes a control means for reducing the filling amount of intake air. As means for reducing the intake air filling amount when the octane number is low, for example, means for delaying the closing timing of the intake valve when the octane number is low through a valve timing changing means, or Sometimes, there are means to lower the supercharging pressure.

(Description of Embodiments) Referring to FIG. 1, a cylinder block 1 of an engine E has a cylinder bore 2 formed therein, and a reciprocating piston 3 is disposed within the cylinder bore.

A cylinder head 4 is mounted on the upper part of the cylinder block 1, and a space formed by the upper part of the cylinder bore 2 and the recess formed in the lower part of the cylinder head 4 constitutes a fuel chamber 5. The cylinder head 4 also has an intake pipe 6.
are connected to each other, and an intake passage 7 is formed so as to communicate with the intake passage of the intake pipe 6 and the fuel chamber 5. Also,
An exhaust passage 9 is formed on the opposite side of the intake passage 7 so as to communicate the fuel chamber 5 and the exhaust pipe 8. Further, an intake valve 10 is combined with the intake boat of the intake passage 7, and an exhaust valve 11 is combined with the exhaust boat of the intake passage 9, respectively. Valve stems 10a and 11a of the intake valve 10 and the exhaust valve extend upward and are slidably supported by the cylinder head 4 via valve guides 12 and 13. In addition, the intake valve 10 and the exhaust valve 11 have a valve spring 1
4.15, it is always biased in the closing direction.

At the upper part of the cylinder head 4, there are provided valve operating mechanisms 17 and 18 on the intake and exhaust sides for controlling the opening and closing of the intake and exhaust valves 10 and '11, respectively.

These valve train mechanisms 17 and 18 are covered by a cylinder head cover 16.

The intake side valve mechanism 17 includes an intake side camshaft 19 drivingly connected to a crankshaft (not shown) of the engine.
In addition, the exhaust side valve mechanism 18 is also provided with an exhaust side camshaft 20 which is also drivingly connected to the crankshaft, and the intake side and exhaust side camshafts 19 and 20 have shafts for the intake valve 10 and the exhaust valve 11, respectively. cams 21 and 22 are formed.

The intake valve mechanism 17 is also provided with a variable valve timing device 23 that variably controls the valve timing of the intake valve IO. The variable timing device 23 includes a tappet 24 interposed between the cam 21 of the intake camshaft 19 and the valve stem 10a of the intake valve 10, and a fitting that slidably fits and holds the tappet 24. A rotating member 25 having an insertion hole 25a and a lower surface 25b formed in an arc shape corresponding to the arc-shaped inner surface of the cylinder head 4, and rotatably supported on the intake side camshaft 19; , and a drive device 26 for rotating the rotating member 25 around the intake camshaft 19. A connecting pin 25e extending parallel to the intake camshaft 19 is integrally attached to the upper end of the upper member 25C.

Further, the drive device 26 includes a cylinder head cover 16.
a sliding rod 27 that is supported so as to be able to reciprocate in a direction perpendicular to the intake side camshaft 19 and has an engaging portion 27a that engages with the connecting pin 25e of the rotating member 25; It is provided with an electric actuator 28 which is drivingly connected and causes the sliding rod 27 to reciprocate. Therefore, the rotation member 25 is moved by the operation of the actuator 28.
The pressure receiving part of the tappet 24 and the cam 21 of the intake side camshaft 19 are rotated in a predetermined direction from a reference position where the sliding direction of the tappet 24 and the opening/closing direction of the intake valve 10 match, and the pressure receiving part of the tappet 24 and the cam 21 of the intake side camshaft 19 move together with the rotating member 25. The closing timing of the intake valve 10 can be changed by changing the timing of contact with the intake valve 10. For example, when the sliding rod 27 is moved to the right in the figure and the rotating member 25 is rotated counterclockwise in the same direction as the rotational direction of the intake side camshaft 19, the cam top of the cam 21 and the tappet 24 are rotated. The timing of contact with the intake valve 10 becomes earlier, and the timing of closing of the intake valve 10 becomes earlier. Conversely, when the sliding rod 27 is moved to the left and the rotating member 25 is rotated clockwise in the opposite direction to the rotational direction of the intake side camshaft 19, the cam top of the cam 21 and the tappet 24 are rotated. The contact timing is delayed, and the closing timing of the intake valve 10 can be delayed. Note that there is a fitting hole 4 of the cylinder head 4 between the valve stem lla of the exhaust valve 11 and the cam 22 of the exhaust side camshaft 20.
A tappet 29 is inserted and held in a slidable manner within a.

Further, in the engine control device of this example, a specific gravity sensor 31 for detecting the specific gravity of fuel is disposed in the fuel tank 30 in order to detect the octane number of the fuel.

A float 32 is arranged in a portion surrounded by a shaped frame 35, and a thermistor 33 is attached to the surface of the float 32. The exposed height of the float from the liquid level changes depending on the specific gravity of the fuel. That is, the ratio of the length of the thermistor exposed from the liquid surface to the length provided in the liquid changes.

The part of the thermistor that is corroded by the liquid releases a larger amount of heat than the part exposed in the gas phase, so if the ratio of the length of the thermistor's gas phase part to the liquid part changes, the resistance value of the thermistor will change. changes. Therefore, the specific gravity of the fuel can be determined by measuring the resistance value of the thermistor. Also, the specific gravity and octane ratio are as the specific gravity increases.
Since the octane number also increases, changes in the octane number can be known by detecting the specific gravity. Further, when detecting the octane number based on the specific gravity in this way, it is necessary to perform correction according to the temperature of the fuel 36, so a temperature sensor 37 for detecting the temperature of the fuel 36 is provided. Furthermore, since it is necessary to perform detection while the liquid level of the fuel 36 is stationary, for example, the cap opening/closing detection switch 39 is set so that detection is performed only when the cap 38 of the fuel tank 30 is closed after fuel injection. is provided.

Further, in order to control the actuator 28, a controller 34 preferably constituted by a microcomputer is provided. Signals from the specific gravity sensor 31, fuel temperature sensor 37, and cap opening/closing detection switch 39 are input to the controller 34 in order to obtain the octane number. In addition, each contact 43a for high octane number, low octane number, and automatic use can be used to control the compression ratio by manually specifying high octane number or low octane number when the specific gravity sensor 31 is out of order. , 43b.

A manual octane switch 43 with 43c is provided and the signal from this switch 43 is also connected to the controller 3.
4 is input. A display section 44 is provided to display the indicated position of the switch 43 with a lamp, and the display section 44 is activated by a signal from the controller 34. The controller 34 also receives signals from a rotation sensor 45 that detects the engine rotation speed and an intake negative pressure sensor 46 that detects the engine load by detecting the intake negative pressure downstream of the throttle valve. Ru.

Furthermore, the controller 34 includes the actuator 2
A signal from a position sensor 47 that detects the current value PO of the closing timing of the intake valve 10 based on the operating amount of 8 is also input. The controller 34 calculates these various signals and, based on the results, issues a command signal to the actuator 28 to provide appropriate valve timing.

An example of control by the control device of the present invention will be described with reference to the flowchart in FIG.

The controller 34 reads signals from the rotational speed sensor 45, intake sensor 46, fuel temperature sensor 37, specific gravity sensor 31, and cap open/close switch 39. After confirming with the cap opening/closing switch 39 that the fuel has just been injected into the fuel tank 30, the octane number of the fuel is calculated based on the signal from the specific gravity sensor 31.

Next, temperature correction of the octane number is performed according to the signal from the fuel temperature sensor 37. Next, the octane number switch 43
A command to display the position is output to the display section 44, and a target closing timing θ of the intake valve 10 corresponding to the position is determined. That is, when the position of the switch 43 is set to the high octane or low octane position, the predetermined high octane intake valve closing timing θ□ or low octane intake valve closing timing θ1 is set to the target intake, respectively. Adopted as the valve closing timing θ. When the position of the octane number switch 43 is set to the automatic position, the intake valve closing timing corresponding to the octane number at that time is selected from the map of intake valve timing corresponding to the octane number,
The value is adopted as the target intake valve closing timing θ.

Next, the operating zone is determined based on the signals from the rotational speed sensor 45 and the intake negative pressure sensor 46, and the operating zone is set when the rotational speed N is smaller than the set rotational speed N1 and the set intake negative pressure P1.
When the intake negative pressure P is smaller than , that is, when the engine is in a low rotation and high load zone where knocking is likely to occur, a control signal is output to the actuator 28 so that the closing timing of the intake valve 10 reaches the target value θ. do.

As a result of such control, the opening characteristics of the intake and exhaust valves are as shown in Figure 3. In the low-speed, high-load zone, the intake valve characteristics a for regular gasoline with a low octane number are the same as those for high-octane gasoline with a high octane number. Compared to the characteristics, the timing is delayed, and therefore the valve closing timing is also delayed. As a result, in the case of low-octane fuel, the valve remains open even after the piston reaches bottom dead center, causing intake air to blow back, reducing the high charge somewhat, and suppressing the occurrence of knocking. Ru. In addition, with high-octane gasoline, the intake valve opening characteristic is such that the intake valve closes early, which reduces intake air blowback in low-speed, high-load zones, secures a high filling amount, and improves output. can be achieved.

(Effects of the present invention) According to the present invention, when low octane fuel is used, high filling of the intake air is appropriately suppressed, so that the occurrence of knocking can be effectively prevented. .

On the other hand, according to the present invention, it is possible to cope with high octane fuel without any problem and to ensure high output.

Although the above-described embodiments have been described in connection with valve timing control according to octane number, the present invention is not limited thereto and can be applied to other engines. For example, in an engine equipped with a supercharger, the above-mentioned effects can be obtained by reducing the supercharging pressure when using low octane fuel.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an engine according to an embodiment of the present invention, FIG. 2 is a flowchart showing an example of control according to the present invention, and FIG. 3 is an intake/exhaust valve characteristic diagram. E...Engine, 1.Old cylinder block, 4.Cylinder head, 7.Old intake passage, 9.Exhaust passage, 10.・・Intake valve,
11...Exhaust valve, 19.20...Camshaft, 28...Actuator, 34...
····controller.

Claims (1)

[Claims] An octane number detection means for detecting the octane number of fuel supplied to the engine, and in response to a signal from the octane number detection means,
1. An engine control device comprising: control means for reducing the amount of intake air when the octane number of supplied fuel is low compared to when the octane number is high.