JPH0792043B2 - Engine overheat suppression device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine overheat suppressing device suitable for use in outboard motors and the like.

[0002]

2. Description of the Related Art When an engine is operated in an overheated state, problems such as piston seizure may occur and the engine may be damaged. In particular, in an engine for an outboard motor or the like that continuously operates at a constant speed, even if these troubles occur during high speed operation, the driver may not be able to immediately take appropriate measures.

Therefore, conventionally, there has been proposed an overheat suppressing device which detects an abnormal increase in engine temperature and decelerates the ignition cylinder to decelerate the engine rotation speed to prevent damage due to overheating of the engine.

[0004]

However, since the above-described conventional overheat suppressing device causes all of a plurality of ignition cylinders to misfire at the same time, the engine deceleration state that can surely suppress the occurrence of overheating. In order to obtain the above, there is a possibility that the engine rotation speed and the hull speed may suddenly decrease.

Further, since the above-described conventional overheat suppressing device causes all of a plurality of ignition cylinders to misfire simultaneously, the engine is completely stopped, and as a result, water cooling or air cooling of the engine is also stopped. Even if the engine is decelerated by misfire control, it becomes impossible to obtain the cooling effect of water cooling or air cooling, and it becomes difficult to reliably suppress the occurrence of overheat.

According to the present invention, when the engine temperature rises abnormally,
An object of the present invention is to provide an overheat suppressing device capable of decelerating an engine speed without shock and reliably suppressing occurrence of overheat.

[0007]

SUMMARY OF THE INVENTION The present invention relates to an overheat suppressing device for an engine composed of three or more cylinders, when the engine speed exceeds a predetermined value and the engine speed exceeds a predetermined value. The control for sequentially extinguishing a plurality of cylinders other than some cylinders at predetermined time intervals can be started, and the control is not performed when the engine speed is less than the predetermined speed. .

[0008]

[Operation] When the engine temperature rises abnormally, a plurality of cylinders other than some of the cylinders are sequentially misfired at predetermined time intervals,
The engine speed can be gradually reduced without shock, and the occurrence of overheat can be reliably suppressed.

During the above-mentioned misfire control, after a plurality of cylinders have been successively misfired, the operation of some of the cylinders is finally continued, so that the water cooling or air cooling or the air cooling of the engine due to the complete stop of the engine is avoided. Below,
The engine can be cooled while decelerating, and the occurrence of overheat can be reliably suppressed.

If the engine speed is higher than the predetermined speed, the misfire control can be started, and if the engine speed is lower than the predetermined speed, the control is not performed. Misfire control is not performed in the low rotation range where the rotation sustainability is weak. Therefore, the engine does not stop due to a reduction in output due to misfire, and it is possible to reliably suppress the occurrence of overheat while maintaining the deceleration state. Exhaust pipes derived from each cylinder are gathered into one and downward
In the outboard engine of the type guided by
Due to the sound, the temperature of the lowest cylinder is the highest.
Tend to I tried to misfire this cylinder first
So, gather the exhaust pipes derived from each cylinder into one
Engine overheat when led down
It is possible to reliably suppress the occurrence of

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a partially cutaway plan view showing an example of a V-type 6-cylinder two-cycle engine for outboard motors, to which the present invention is applied, at 60-degree equidistant ignition, and FIG. 2 is a front view of the engine. FIG. 3 is an ignition control system diagram of the engine.

The engine 11 is a V-type 6-cylinder engine with a 90-degree bank, and includes a first cylinder 11A, a second cylinder 11B, and a third cylinder 11B.
The cylinder 11C and the fourth cylinder 11D, and the fifth cylinder 11E and the sixth cylinder 11F each form a V-shape. Engine 11
The crankshaft 12 is vertically arranged, and a piston 14 housed in each horizontally arranged cylinder is connected to the crankshaft 12 via a connecting rod 13. A cylinder head 16 defining a combustion chamber 15 for each cylinder is fixed to the rear of the engine 11. At the front of the engine 11, a reed valve 18 provided in an intake passage 17 corresponding to each cylinder is provided.
The carburetor 20 and the intake box 21 for supplying the air-fuel mixture to the crank chamber 19 of each cylinder are connected via the. 22
(22A to 22F) are spark plugs, and 23 is a throttle valve.

The engine 11 is provided with a controller 24 composed of a microcomputer so that the ignition timing can be electronically controlled. That is, the controller 24 has an ignition timing setting device 25 (CPU) and an ignition signal generator 26, as will be described later in detail, and includes a pulsar coil 27, a crank angle signal (timing signal) generator 28, and a throttle detector 2.
9. Based on the output signals of the temperature detector 30A and the overheat detector 30B, the optimum ignition timing is set for each operating state of the engine 11, and the CDI unit 31 is used to set the ignition timing.
The ignition states of the spark plugs 22A to 22F of each cylinder can be controlled. In FIG. 3, reference numeral 32 is a sampling cycle generation circuit for the ignition timing setting device 25.

Here, as shown in FIG. 4, a boss portion 34 of a rotor 33 forming a magnet is fixed to an upper end portion of the crankshaft 12 of the engine 11 by a half-moon key 35 and a nut 36. A permanent magnet 37 is fixed to the inner surface of the rotor 33. Reference numeral 38 denotes a power-generating coil, and a plurality of coils 38 are annularly arranged so as to correspond to the inner surface of the permanent magnet 37. These power generation coils 38 are fixed to a plurality of legs 39 provided on the engine 11.

Reference numeral 40 denotes a permanent magnet, which has N and S poles at two diametrical positions on the boss portion 34 of the rotor 33.
It is fixed so that it is located at 80 degree intervals. Further, 27 (27A, 27B, 27C) is a three pulsar coils, which is a support base 41 supported by the engine 11.
Are fixed to the inner surface of an annular holder 42 that is integrated with each other at 120 degree intervals. That is, in the pulsar coil 27, every time the crankshaft 12 rotates by 60 degrees, one of the pulsar coils 27A, 27B, and 27C faces the N pole or the S pole of the permanent magnet 40 once, and as shown in FIG. Pulses P ₁ , P ₄ for the first cylinder 11A and the fourth cylinder 11D are induced in the pulsar coil 27A, and a pulse P for the second cylinder 11B and the fifth cylinder 11E is generated in the pulsar coil 27B.
₂ and P ₅ are induced, and the pulses P ₃ and P ₆ for the third cylinder 11C and the sixth cylinder 11F are induced in the pulsar coil 27C.

A ring gear 43, which receives the rotational force of a starter motor (not shown) when the engine is started, is fixed to the outer peripheral portion of the rotor 33.
The crank angle signal generator 28 fixedly arranged on the engine 11 is arranged oppositely. In the crank angle signal generator 28, a pulse facing each meshing tooth of the ring gear 43 is induced as the crankshaft 12 rotates.

Each output pulse P _{1 of the} pulsar coil 27
~ P ₆ is the waveform shaping circuit 4 of the controller 24 as shown in FIG.
4 is encoded by the encoder 45 and sequentially transmitted to the preset counter 46 via the ignition timing setter 25 in a mutually distinguishable state. The output pulse of the crank angle signal generator 28 is, as shown in FIG.
In the double-cycle circuit 47 of the controller 24, the subdivided pulse indicated by P _c in FIG. 6 is transmitted to the preset counter 46.

The pulsar coil 27, the crank angle signal generator 28, and the preset counter 46 constitute the crank angle detector of the present invention. That is, the pulsar coil 27 generates the pulses corresponding to the number of cylinders corresponding to the constant angle position of the crankshaft 12, that is, the reference angle signal of the crankshaft 12, in one revolution of the crankshaft 12. Therefore, the pulsar coil 27 functions as a reference angle signal generator for the crankshaft, and the preset counter 46 counts the number of pulses generated by the crank angle signal generator 28 after the pulse generation of the pulsar coil 27, thereby determining the angular position of the crankshaft 12. Can be detected. still,
As shown in FIG. 6, when detecting the angular position of the crankshaft 12, as a reference angular signal for the advance angle θ with respect to the crank angular position of the N cylinder (for example, the second cylinder 11B), for example, its top dead center (TDC), Using the pulse P ₁ generated by the pulser coil 32A corresponding to the N-1 cylinder (for example, the first cylinder 11A), the pulse generation number ΣP _c of the crank angle signal generator 33 after the point P _{1 is} generated may be counted. For example, when the pulse generated by the pulsar coil 27B corresponding to the N cylinder is used as the reference angle signal,
In contrast to the need to count the number of pulses for 60 ° -θ, for 6 cylinders, it is sufficient to count ΣP _c for 60 ° -θ, and the pulse generation of the pulser coil 27B corresponding to the N cylinder is required. The angle θ before the time point can be indexed with high accuracy by counting a smaller number of pulses.

The pulsar coil 27 also functions as an engine speed detector. That is, since the pulsar coil 27 generates pulses for the number of cylinders for each revolution of the crankshaft 12, the ignition timing setter 25 counts the number of pulses generated by the pulsar coil 27 within a unit time to determine the crankshaft. It is possible to detect the rotation speed of 12, that is, the engine speed.

Further, the throttle detector 29 is directly connected to the throttle shaft 23A of the carburetor 20, and can detect the throttle opening of the carburetor 20, that is, the amount of intake air to each cylinder by a potentiometer method.

The temperature detector 30A is of the thermistor type, for example, and has a third cylinder 11C and a fifth cylinder 11E.
It is attached to the cylinder head 16 between, and the temperature of the engine 11 can be detected through the detection of the cooling water temperature. The detection results of the throttle detector 29 and the temperature detector 30A are alternately output from the A / D converter 2 via the buffer 29A.
9B and is transmitted to the ignition timing setting device 25 in a digitized state in the A / D converter 29B.

Further, the overheat detector 30B
Consists of a bimetal contact type temperature sensitive switch,
Each cylinder head 1 of the first cylinder 11A and the second cylinder 11B
Attached to the 6 detects the coolant temperature in the cylinder head 16, for example, t ₁ ° C. or more detection results of the ignition timing setter 2
5 can be transmitted.

The specific ignition control procedure of the controller 24 will be described below. First, the control of the controller 24 during normal operation will be described. Ignition timing setting device 2 of controller 24
In FIG. 5, the optimum ignition timing for each combination of the engine speed and the throttle opening as the intake air amount is predetermined by a map (or functional expression) type. (still,
The applicant has already clarified an example of the map set in the ignition timing setting device 25 in the specification and drawings attached to Japanese Patent Application No. 57-146268. Therefore, during normal operation of the engine 11, the ignition timing setting device 25 determines the engine speed obtained by counting the output pulses of the pulser coil 27 as described above, and the throttle opening or intake amount detected by the throttle detector 29. Based on the air amount and the map, the optimum ignition timing corresponding to the operating state at that time is set. In this way, the ignition timing setting device 25 transmits the optimum ignition timing of each cylinder to the preset counter 46 of the ignition signal generator 26.

On the other hand, the preset counter 46 is also a part of the crank angle detector in the present invention as described above, and the pulsar coil 2 as the reference angle signal generator.
The number of pulses generated by the crank angle signal generator 28 after the time point of 7 pulse generation is counted to detect the angular position of the crankshaft 12.

Therefore, the ignition signal generator 2 according to the present invention is used.
In the preset counter 46 as a part of 6, the crank angle counted as described above is calculated by the ignition timing setter 25.
The ignition signal is transmitted to the waveform shaping circuit 48 at the time point of the optimum ignition timing transmitted from. The ignition signal transmitted to the waveform shaping circuit 48 is transmitted to the CDI ignition device corresponding to each cylinder of the CDI unit 31. Each of the CDI ignition devices of the CDI unit 31 starts charging the ignition capacitor with the voltage generated in the magneto power generation coil 38, and then operates the gate of the SCR by the ignition signal current generated in the ignition signal generator 26. At the same time when the ignition coil is turned on, the electric charge stored in the ignition capacitor is suddenly applied to the primary side of the ignition coil, and
A high voltage is generated on the next side, and spark plugs 22A to 22F of each cylinder are generated.
Discharge is possible. That is, according to the advance control by the controller 24, the ignition timing setting device 25 selects the ignition timing determined in advance by the map type, so that the optimum ignition without causing abnormal combustion in the normal operating state of the engine. It becomes possible to ignite at the time.

Next, the overheat suppressing control by the controller 24 will be described. Here, the ignition timing setting device 25
Is one of all cylinders when the engine temperature is a predetermined temperature, for example, t ₁ ° C. or more, the throttle opening is a predetermined opening, for example, α ₁ degree or more, and the engine rotation speed is a predetermined speed, for example, N ₁ rpm or more. The ignition timing setting signals for the cylinders to be misfired are not transmitted to the ignition signal generator 26 so that the plurality of cylinders other than the partial cylinders are sequentially misfired at predetermined time intervals. In Figure 7, the horizontal axis is time H
Is a diagram showing the control state by the overheat suppression control with the engine speed N on the vertical axis.
In the engine 11 consisting of A to 11F, at the bottom
Positioned sixth cylinder 11F first, then fifth cylinder 11
E, the third cylinder 11C, and the second cylinder 11B in order, for example, h ₁
~h to misfire at a time H ₁ of ₂ seconds, showing a state of continuing the operation of the engine 11 only by finally two cylinders of the first cylinder 11A and the fourth cylinder 11D.

An overheat suppressing program shown in FIG. 8 is written in the controller 24, and the overheat suppressing control is executed as follows based on this program. That is, the controller 24 inputs the engine temperature detected by the overheat detector 30B, that is, the temperature sensitive switch to the ignition timing setting device 25 (step), and determines whether the detection result is t ₁ ° C or more (step). . If the determination result of the step is NO, the process returns to the step, and if the determination result is YES, it is determined whether the throttle opening detected by the throttle detector 29 is α ₁ degree or more (step). If the determination result of the step is NO, the process returns to the step and the determination result is YE.
If S, it is determined whether the engine speed detected by counting the output pulses of the pulser coil 27 is N ₁ rpm or higher (step). If the determination result of the step is NO, the process returns to the step and the determination result is Y.
If it is ES, the ignition timing setter 25 executes the misfire control shown in FIG. 7 (step-a), holds the engine speed at N ₁ rpm (step-b), and then the throttle detector 29 It is determined whether the detected throttle opening is less than α ₁ degree (step-c). Step-c
If the result of the determination is NO, the process returns to step-b. If the result of the determination is YES, the misfire is canceled (step-d) and the process returns to step. Further, when the determination result of the step is YES, the controller 24 sounds a buzzer to give a warning to the driver (step), and whether the engine temperature detected by the temperature detector 30A is t ₂ ° C or lower. (Step). If the determination result of the step is NO, the process returns to the step and the buzzer continues to ring, and if the determination result is YES, the buzzer stops ringing (step) and returns to the step.

[0028] In step -c of the overheating suppression program, the reason for determining whether the throttle opening is less than alpha ₁ degree, step If the -a, engine temperature decreases after the operation of the misfire control by -b In addition, to prevent the engine from returning to normal operation and losing safety without notice, the misfire control state is not automatically released even when the engine temperature drops, and the throttle is controlled by the driver. It is to ensure the manual release of the misfire control state that involves opening operation. Further, in the step of the overheat suppression program, the reason for determining whether the engine rotation speed is N ₁ rpm or more is that when the engine 11 is N ₁ rpm or less, the operation of the engine 11 is performed in some cylinders 11A. , 11D alone is difficult to continue.

Therefore, according to the overheat suppressing control by the controller 24, when the engine temperature rises abnormally,
A buzzer sounds to give a warning to the driver, and at the same time, a plurality of cylinders other than some of the three or more cylinders are misfired at predetermined time intervals, so that the engine speed is gradually increased without shock. It is possible to decelerate and surely suppress the occurrence of overheat. That is, since the deceleration state progresses stepwise, it is possible to obtain the deceleration state necessary for suppressing overheating without causing a sharp decrease in the engine rotation speed and the hull speed. Further, in this overheat suppression control, after the plurality of cylinders have been successively misfired, the operation of some of the cylinders is finally continued, so under the condition that the water cooling or the air cooling of the engine due to the complete stop of the engine is avoided. By decelerating the engine, it is possible to reliably suppress the occurrence of overheat. Also, the engine speed is
If the number of revolutions is higher than the fixed speed, misfire control can be started.
If the rotation speed is less than the constant speed, the above control is not performed.
Even under the overheat condition,
Do not perform misfire control in the low revolution range where the rotation sustainability is weak.
Yes. Therefore, the engine stops due to the output reduction due to misfire.
There is no such thing, and overheating is performed while maintaining the deceleration state.
It is possible to surely suppress the occurrence of defects. Also, each cylinder
Collect the exhaust pipes derived from 11A to 11F into one
In the outboard engine 11 that is guided downwards
Is the sixth cylinder located at the bottom due to the influence of exhaust gas.
The temperature of the cylinder 11F tends to be the highest. This 6th mind
Since the cylinder 11F was made to misfire first, each cylinder 1F
Collect the exhaust pipes derived from 1A-11F into one
When the engine 11 is overdriven,
It is possible to surely suppress the occurrence of heat.

In the above embodiment, the case where each cylinder under the misfire control is sequentially misfired at the constant time interval H ₁ has been explained, but the time interval for the misfire control is sequentially changed with the progress of the misfire to the succeeding cylinder. It may be one that does.

In the above embodiment, the present invention is applied to a V-type 6-cylinder engine.
The present invention can be applied to any engine having substantially three or more cylinders, and can of course be applied to other types of engines.

[0032]

As described above, according to the present invention, when the engine temperature rises abnormally, the engine speed can be gradually reduced without shock and the occurrence of overheat can be reliably suppressed.

[Brief description of drawings]

FIG. 1 is a partially cutaway plan view showing an embodiment of an outboard engine according to the present invention.

FIG. 2 is a plan view showing the engine.

FIG. 3 is an ignition control system diagram of the engine.

FIG. 4 is a cross-sectional view showing a crankshaft upper structure of the engine.

FIG. 5 is an explanatory diagram showing a pulsar coil arrangement state of the engine.

FIG. 6 is a waveform diagram showing output pulses of a pulser coil and a crank angle signal generator.

FIG. 7 is a diagram showing an overheat suppression control state.

FIG. 8 is a flowchart showing an overheat suppressing program.

[Explanation of symbols]

 11 Engines 11A to 11F Cylinders 24 Controllers 25 Ignition Timing Setting Devices 26 Ignition Signal Generators 30B Overheat Detectors 31 CDI Units

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliographic references Sho 58-124665 (JP, U)

Claims (1)

[Claims] 1. An overheat suppressing device for an engine, comprising a crankshaft vertically arranged and comprising three or more cylinders, wherein the engine speed exceeds a predetermined value when the engine temperature exceeds a predetermined value. , Other than some cylinders, from the cylinders located at the bottom,
To allow starting the control to be lost fire sequential predetermined time interval,
An engine overheat suppressing device, wherein the control is not performed when the engine speed is lower than the predetermined speed.