JPH1172040A - Overheat sensing method for outboard motor engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sense occurrence of an overheat with no risk of misjudgement even immediately after the engine is started by solving the demerits and problems in the conventional overheat sensing method for an outboard motor engine. SOLUTION: An overheat sensing method for an outboard motor engine consists of such procedures that the cooling water is discharged from a water jacket when the engine is stopped and cooling water is supplied to the water jacket after the engine is started, wherein a temp. sensing means is installed in the water jacket so that the internal temp. change is sensed, and overheat of the engine is sensed on the basis of the obtained temp. change.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method for detecting overheating in an engine for an outboard motor.

[0002]

2. Description of the Related Art Conventionally, in outboard motor engines,
It is known to perform overheat warning control such as misfire control for the purpose of protecting the engine when a trouble occurs in the cooling system. The above-described detection of a trouble in the cooling system, that is, detection of overheating is performed by monitoring the temperature in the water jacket of the engine with an overheat switch such as a bimetal switch. When the temperature becomes equal to or higher than Tlim, for example, equal to or higher than the boiling point temperature of the cooling water, the overheat switch is turned on and it is determined that the engine is in an overheat state.

[0003]

However, in the case of an outboard motor engine, since the seawater is used as the cooling water, all the cooling water is drained from the water jacket once when the engine is stopped. And the empty water jacket becomes 1 when the engine is stopped.
The lubricating oil, which has been heated up to a temperature of about 30 °, is heated by the influence of the lubricating oil and has a problem that the temperature is considerably high. FIG.
Fig. 3 shows the changes over time in the temperature inside the water jacket, the temperature of the lubricating oil, and the engine speed. As shown in the drawing, after the engine is stopped, the temperature To of the lubricating oil gradually decreases, but it takes time for the lubricating oil to cool down.
Further, the cooling water is drained from the water jacket after the engine is stopped, and there is no cooling element in the water jacket. Therefore, the temperature Tw in the water jacket is temporarily reduced after the cooling water is drained. Ascending, for a certain period of time, threshold Tlim for judgment of overheating
(85 ° C. in FIG. 16). And
Since the temperature of the lubricating oil temperature To decreases as the temperature of the lubricating oil decreases and the temperature effect of the lubricating oil decreases, the temperature Tw in the water jacket gradually decreases later than the decrease in the lubricating oil temperature To. Drops and drops to normal temperature. While the engine is stopped, the overheat determination is not performed. Therefore, there is no problem even if the temperature Tw in the water jacket is higher than the threshold value Tlim as described above. However, as shown in FIG. If the engine is restarted before Tw is cooled down to the threshold value Tlim or less, the overheat switch is turned on immediately after the engine is started, and it is erroneously determined that overheating has occurred. In the conventional overheat detection method, in order to prevent the above-described erroneous determination at the time of restarting the engine, overheat is not detected until a predetermined time ts has elapsed after the engine is started. Specifically, as shown in the flowchart of FIG. 17, immediately after the engine is started, the state of the overheat switch is monitored, and when the output of the overheat switch is turned on, that is, when the temperature Tw in the water jacket becomes equal to the threshold Tlim
If it becomes higher, it is determined whether or not the engine has just started, based on whether or not the engine speed is less than or equal to 2000 rpm (step 2). After the masking (step 3), it is determined again whether or not the overheat switch is ON (step 4). If the overheat switch is ON, it is determined that the temperature has not decreased, and an overheat signal is output. If the overheat switch is turned off in the determination in step 4, it is determined that the temperature has dropped, and the process returns to the overheat switch monitoring state (step 1).
If it is determined that the engine has just started, after masking for a predetermined time ts (here, 90 seconds) (step 5), it is determined again whether or not the overheat switch is ON (step 4). It was checked whether there was a temperature drop. Thus, after starting the engine,
By taking the masking time ts immediately after the start of the engine sufficiently longer than the masking time during normal operation of the engine in consideration of the time when the cooling water is sucked into the water jacket, erroneous determination of overheating occurs immediately after the start of the engine. That is prevented. However, if the masking time ts immediately after starting the engine is increased,
Although the above-described erroneous determination is prevented, if a trouble actually occurs in the cooling system, there is a problem that detection of overheating is delayed and a load is imposed on the engine. The present invention solves the drawbacks and problems of the above-described conventional method for detecting overheating of an engine in an outboard motor, and detects overheating in an outboard engine that can detect overheating immediately after engine start without erroneous determination. It aims to provide a detection method.

[0004]

According to the present invention, there is provided a method for detecting overheating in an outboard engine according to the present invention, wherein when the engine is stopped, cooling water in a water jacket is drained to start the engine. An overheat detection method for an outboard motor engine that supplies cooling water into a water jacket later, wherein a temperature detection unit is provided in the water jacket, and a temperature change in the water jacket is detected by the temperature detection unit. The overheat of the engine is detected based on the change.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method for detecting overheating in an outboard engine according to the present invention will be described with reference to an embodiment shown in the accompanying drawings. FIG. 1 is a schematic perspective view of an outboard motor-equipped marine vessel equipped with an engine to which the method for detecting overheat in an outboard engine according to the present invention is applied, and FIG. It is a schematic diagram showing the relation between the wiring structure on the outboard motor side including the control device that sometimes performs the overheat warning control and the wiring structure on the hull side. As shown in the drawing, the outboard motor 1 is mounted on the stern of an open deck type hull 2, and a steering handle 3, a seat 4, a throttle and shift lever 5, a main switch 6, a stop switch 7 are provided at the front of the hull 2. , A meter panel 8, a fuel tank 9, and a battery 10 are arranged. The outboard motor 1 is provided with an engine 11, an AC generator (not shown), and an ignition control device 30 for controlling the ignition timing of the engine 11. Although not shown, the outboard motor 1 is also provided with a propulsion propeller, a power transmission system for transmitting the driving force of the engine 11 to the propeller, an oil pump, a cooling water supply pump, and the like, in addition to those described above. I have. The engine 11 is composed of an in-line four-cylinder four-cycle engine in which the phase of each cylinder is shifted by 180 °.
A crankshaft is vertically mounted on the upper part of the motor, and the driving force rotates a propulsion propeller provided below the outboard motor 1 to obtain a propulsion force. In the engine 11, as is well known, the first and fourth cylinders and the second and third cylinders operate in the same phase when viewed from the rotation of the crankshaft. Two pulsar coils 12, 13 are provided at 180 ° intervals on a crankshaft (not shown) of the engine 11, and one (first) pulsar coil 12 detects the ignition timing of the first cylinder and the fourth cylinder, The other (second) pulser coil 13 is configured to detect the ignition timing of the second cylinder and the third cylinder. Also, the engine 11
A thermo sensor 14 for monitoring the temperature in the water jacket is provided near the suction port of the water jacket (not shown), and further, a lubricating oil supply passage (not shown) downstream of an oil pump (not shown). A hydraulic switch 15 for monitoring the hydraulic pressure in the lubricating oil supply passage is provided on each side, and these pulsar coils 12, 13 and each switch 1 are provided.
The ignition timing control is performed by the ignition control device 30 based on the signals from 4 and 15. The ignition control device 30 preferably inputs information on a throttle opening and a throttle change rate and information on a shift state of a shift lever,
Based on these pieces of information, ignition retarding / advancing angle control in accordance with the operating state of the engine and ignition control in accordance with the shift state can be performed, but detailed description of these methods is omitted here.

(Power supply circuit) As shown in FIG.
The battery 10 on the side of the hull 2 is connected to a charging coil 16 of the AC generator on the side of the outboard motor 1 via a rectifying constant voltage device 17 (for example, a rectifier and a regulator), and these constitute a charging circuit. The charging circuit supplies power to electrical components such as an ignition control device 30 of the engine 11 provided in the outboard motor 1 and a meter provided in the hull 2 and charges the battery 10. Have been. The battery 10 on the hull 2 and the charging coil 16 on the outboard motor 1 are connected via an appropriate connector 18 and a main fuse 19, and the main fuse 1
At 9, a circuit protection is provided so that a large current does not flow from the battery 10 to these circuits when the circuits constituting the ignition control device 30 and the meter and the like are short-circuited. On the outboard motor 1 side of the charging circuit, an ignition power supply circuit 20 for supplying electric power to the ignition control device 30 and a hull power supply circuit 21 for supplying electric power to electric components of the hull 2 are connected. The ignition power supply circuit 20 is turned on / off by a contactless switch circuit 31 provided in the ignition control device 30, and the hull power supply circuit 21 is turned on / off by a contact type main switch 6 provided in the hull 2. It is turned off. A circuit portion on the outboard motor 1 side of the hull power supply circuit 21 and a circuit portion on the hull 2 side are connected via a connector 22.
An accessory fuse 23 for protecting electrical components on the hull 2 side is provided in a circuit portion on the side. Further, a backup circuit 21a is connected downstream of the main switch 7 in the hull power supply circuit 21. The backup circuit 21a returns to the outboard motor 1 again via the connector 24 and is connected to the ignition control device 30. DC voltage is supplied from the hull power supply circuit 21 to the ignition system of the ignition control device 30 even if a disconnection of the ignition power supply circuit 20 or a failure of the switch circuit 31 occurs. It is configured to be able to. The circuit of the ignition control device 30 is formed of a wire having a strength that can withstand at least the maximum current value of the light coil 16 limited by the rectification constant voltage device 17.
The ignition power supply circuit 20 connecting between 0 and the charging coil 16 is not provided with a circuit protection fuse. As shown in FIG. 2, an engine stop circuit 25 is connected to the ignition control device 30. When the stop switch 7 provided on the hull 2 is closed by an operator or the like, the engine stop circuit 25 becomes conductive. Then, the power supplied from the ignition power supply circuit 20 and the backup circuit 21a to the ignition control device 30 is stopped to stop the engine 11.

(Regarding the structure of the control device) The ignition control device 30 includes, in addition to the switch circuit 31, a magnetic flux change in the ignition coils C1 and C2 of the ignition plugs P1 to P4 of each cylinder to cause each ignition plug A CDI circuit 32 for igniting P1 to P4; a CPU 40 for determining an ignition timing of each cylinder and outputting an ignition signal to the CDI circuit 32; a DC voltage from the charging circuit being converted into a constant voltage of about 5 V and C
A constant voltage circuit 34 to be supplied to the PU 40; an input circuit 35 to 3 for converting inputs from the pulsar coils 12, 13 and the switches 14, 15 into digital signals.
8, an ignition signal switching circuit 39 for switching between an ignition signal (hereinafter, referred to as a soft ignition signal) from the CPU 40 and an ignition signal (hereinafter, referred to as a hard ignition signal) from the pulsar coils 12, 13; And a watchdog circuit 33 for monitoring the operation of the CPU 40 and outputting a reset signal to the CPU 40 when an abnormality occurs. Reference numeral 15a in the figure denotes a warning lamp provided on the hull 2, and this warning lamp 15a is lit by a weak current flowing when the hydraulic switch 15 is closed due to a decrease in the hydraulic pressure in the lubricating oil supply passage. To warn the operator of the oil pressure abnormality. The hydraulic switch 15 is connected to the warning lamp 1.
At least the warning lamp 1 in parallel with the circuit comprising 5a
A circuit having a load 15b capable of flowing a current higher than 5a is connected, so that even if the contact resistance of the hydraulic switch 15 increases due to, for example, oxidation of the contact, the hydraulic switch 15 is reliably connected. Make it conductive and CPU4
It becomes possible to send oil pressure abnormality information to 0.

(Regarding the switch circuit) The switch circuit 31 has pulser coils 12, 13 as shown in FIG.
Is input. The switch circuit 31 conducts when signals from the pulsar coils 12 and 13 are input, and switches the 12V DC voltage from the ignition power supply circuit 20 to the CDI circuit 32.
And a non-contact switch element to be supplied to the constant voltage circuit 34. This ensures that the required power is supplied to the CDI circuit 32 and the CPU 40 in the ignition control device 30 immediately after the engine is started. Normally, connection parts such as connectors and mechanical switches may be disconnected due to poor contact or the like, and fuses may also be disconnected due to vibration or the like. Ignition control device 3 without any fuse, connector, or mechanical switch (eg, main switch)
0 and ON / O by the contactless switch circuit 31
Since it is configured to be flip-flopped, the possibility of disconnection is extremely low as compared with a circuit in which a connector, a fuse, and a mechanical switch are interposed. Therefore, the possibility that the power supply to the ignition control device 30 is cut off due to a contact failure, a disconnection, or the like during the operation of the engine is significantly reduced. Further, since the ignition power supply circuit 20 is connected to the battery 10 in addition to the charging coil 16, even if the charging coil 16 fails, the battery 10 supplies power to the ignition control device 30. It is possible. Furthermore, the hull power supply circuit 2
1, the backup circuit 21a connected to the downstream side of the switch circuit 31 is provided. Therefore, even if the ignition power supply circuit 20 is disconnected or the switch circuit 31 fails, the backup circuit 21a is connected to the CDI circuit 32 and the CPU 40. Power supply can be reliably ensured.

(Regarding the CDI circuit) The CDI circuit 3
2 is a first cylinder and a fourth cylinder of the engine 11, or a second cylinder
A simultaneous ignition type circuit for simultaneously igniting the ignition plugs P1 and P4 or P2 and P3 of the cylinders and the third cylinder with the common ignition coil C1 or C2; a charging capacitor 32a; A first thyristor 32b for discharging the ignition energy of the charging capacitor 32a to a first ignition coil C1 common to the ignition plugs P1 and P4; a second ignition coil common to the ignition plugs P2 and P3 of the second and third cylinders C2 is provided with a second thyristor 32c for discharging ignition energy of the charging capacitor 32a. The CDI circuit 32 includes a booster circuit (DD converter) 32d for boosting the 12V DC voltage from the ignition power supply circuit 20 to about 300V, and the battery 10 and the charging coil are connected via the booster circuit 32d. Capacitor 16 for charging ignition energy from a charging circuit comprising
a is charged. That is, the CDI circuit 32 in the ignition control device 30 constitutes a so-called DC-CDI circuit together with the charging circuit, and is configured to charge the charging capacitor 32a sufficiently immediately after the engine is started. .

(Regarding the ignition signal switching circuit)
First and second thyristors 32b and 32 of DI circuit 32
c is turned on when an ignition signal is input, and rapidly discharges the charge stored in the charging capacitor 32a to cause a first discharge.
A sudden magnetic flux change is generated in the ignition coil C1 or the second ignition coil C2, and the ignition plugs P1 and P4 or P2 and P2
A high voltage is induced in the secondary coil of No. 3 to cause spark discharge. The ignition signal is basically determined based on the pulser signals from the first and second pulser coils 12 and 13. In the ignition control device 30, a hard ignition signal using the pulser signal as a direct ignition signal or a pulser signal is used. The CPU 40 calculates an ignition signal output timing suitable for the optimal ignition timing based on the signal, and obtains the C signal at a more optimal timing.
The thyristors 32b and 32c can be made conductive by selectively using any one of the soft ignition signals output from the PU 40. The switching of the ignition signal is performed by an ignition signal switching circuit 39. When a soft ignition signal is output from the CPU 40, the ignition signal switching circuit 39 outputs the soft ignition signal to the thyristor 32.
b or 32c, and outputs a hard ignition signal (pulsar signal) directly sent from the pulser coil 12 or 13 to the thyristor 32b or 32c if the soft ignition signal is not output from the CPU 40. The CPU 40 determines the type of the pulsar signal (that is, the pulsar signal from the first pulsar coil 12 and the second pulsar coil 1).
3), the ignition coil C1 or C2 that causes a change in magnetic flux is determined by the corresponding thyristor 32.
The ignition signal is output to b or 32c. The timing of outputting each ignition signal (i.e., the ignition timing) is calculated based on the period of two consecutive pulsar signals as shown in FIG. Therefore, as shown in FIG. 3, the CPU 40 determines that the pulsar signal has not been input at least twice (ie,
In the case of this embodiment, the pulsar coils 12, 13 are 180
Since the ignition signal switching circuit 39 does not output the ignition signal unless the crankshaft is rotated by 180 degrees or more (at least when the crankshaft rotates 180 degrees or more), the ignition signal switching circuit 39 outputs the signal from the pulsar coil 12 or 13 as soon as the engine is cranked. The hard ignition signal (pulsar signal) is output to the thyristor 32b or 32c of the CDI circuit 32, and when the CPU 40 starts outputting the soft ignition signal, the output signal is switched to the soft ignition signal. A reset signal from the watchdog circuit 33 is also input to the ignition signal switching circuit 39. When the reset signal is input, the output is forcibly switched to the hard ignition signal even during control by the soft ignition signal. . By switching between the hard ignition signal and the soft ignition signal in the ignition signal switching circuit 39 in this manner, regardless of the number or interval of the pulsar coils 12 and 13 (in the case of the present embodiment, the crankshaft is set to 180 degrees or more). As soon as the engine is cranked (without rotating), the ignition can be performed by the hard ignition signal, so that the engine starting performance is improved. Further, after the engine is started, the signal is output at the optimum ignition timing calculated by the CPU 40. Since the ignition control can be performed by the soft ignition signal, the output performance of the engine is improved, and the misfire control described later can be performed. Further, as described above, the ignition signal switching circuit 39 is configured to forcibly switch from the soft ignition signal to the hard ignition signal based on the reset signal from the watchdog circuit 33, so that if the CPU 40 fails, However, at the same time as the watchdog circuit 33 resets the CPU 40, it can automatically switch to the hard ignition signal.

(Regarding CPU) Next, the ignition control device 3
0 will be described. This CPU
40 is the two pulsar coils 12, 1 as described above.
3 to determine the ignition coil for causing a change in magnetic flux and the output timing of the ignition signal, and output a soft signal to either the thyristor 32b or 32c, and the corresponding ignition plugs P1, P4 or P2 And P3
Causes spark discharge. Thereby, two spark plugs P1 and P4 or P2 and P
One of the three is because the corresponding cylinder is at the end of the compression stroke,
The spark discharge actually burns the mixture,
Since the corresponding cylinder is at the end of the exhaust stroke, it merely generates a spark discharge and does not burn the mixture. In this specification, spark discharge of a spark plug is referred to as "ignition", and
The fact that the spark discharge actually burns the mixture is referred to as "ignition". FIG. 4 is a schematic diagram showing each processing function of the CPU 40. As shown in FIG. 4, the CPU 40 determines an ignition timing suitable for the engine operating condition at that time from an ignition timing map prepared in advance based on the engine operating condition such as the engine speed and the throttle opening. And
An ignition timing determining unit 41 for determining an ignition coil to be ignited based on the pulsar signal and an output timing of an ignition signal suitable for the ignition timing; an engine speed calculating unit for calculating an engine speed based on the pulsar signal 42, an overheat judging unit 43 for judging whether or not the engine is in an overheat state based on an input signal from the thermosensor 14, and an input from the engine speed calculating unit 42, the overheat judging unit 43, and the hydraulic switch 15. A misfire cylinder number determining section 44 is provided which determines whether or not it is necessary to reduce the engine speed based on the signal, determines the number of cylinders to be misfired, and outputs the number to the ignition timing decision section 41. The ignition timing determination unit 41 includes an ignition sequence counter 45 for counting the ignition sequence each time a pulsar signal is input from the pulsar coils 12 and 13. The ignition sequence counted by the ignition sequence counter 45 is used as a temporary ignition cylinder. The number is stored as a number (hereinafter, referred to as a virtual ignition cylinder number) (see FIG. 5, this figure shows a pulser signal, a count number of an ignition sequence counter, a virtual ignition cylinder number, an actual ignition cylinder, an ignition plug to be ignited, and FIG. 4 is a diagram showing a relationship between ignition signals output from an ignition timing determination unit 41). Although these processing units 41 to 45 are described separately and independently for convenience, the CPU 40 actually performs the processing of each processing unit according to an operation program stored in a memory (not shown) in advance. The ignition timing and the misfiring cylinder are determined and a soft ignition signal is output.

First, an outline of each processing in the CPU 40 will be briefly described. When the engine 11 starts, a pulsar signal from the pulsar coil 12 or 13 is input to the CPU 40 via the input circuit 35 or 36. The ignition timing determination unit 41 determines the ignition coil C1 or C2 to be ignited according to the type of the pulsar signal as described above, and the timing of the soft ignition signal to be output (that is, the ignition timing).
Is calculated based on the cycle of two consecutive pulsar signals. In addition, the ignition timing determination unit 41 controls the pulsar coil 1
Each time a signal from 2 or 13 is input, the ignition order counter 45 repeatedly counts the first to fourth ignition orders and stores this as a virtual ignition cylinder number. On the other hand, the misfire cylinder number determining unit 44 monitors the supply state of the lubricating oil based on the signal of the hydraulic switch 15 immediately after the engine is started, and monitors whether or not an overheat signal is input from the overheat determining unit 43. Further, based on the engine speed calculated by the engine speed calculation unit 42, it is monitored whether the engine speed is excessive. When the engine 11 falls into any of a poor lubrication state, an overheat state, and an overspeed state, the engine 11 determines the number of misfiring cylinders necessary for engine protection and outputs a misfiring signal to the ignition timing determination unit 41. When the misfire signal is input, the ignition timing determination unit 41 determines the number of the virtual ignition cylinder to be misfired based on the virtual ignition cylinder number, and stops the output of the ignition signal corresponding to that order. Usually, when performing simultaneous ignition,
As described above, since the ignition signals for simultaneously igniting the two cylinders are output based on the pulsar signal from one pulsar coil, which of the two ignition plugs that are simultaneously ignited from the input pulsar signal actually ignites It is not known whether or not the ignition plug is actually being ignited by counting the ignition order counter every time a pulsar signal is input and storing this as a virtual ignition cylinder number as described above. (I.e., the ignition cylinder) can be pseudo-recognized from the pulsar signal, so that the ignition cylinder can be recognized for each cylinder, and misfire can be performed for each cylinder.

Next, an example of the flow of each processing in the ignition timing determination section 41, the overheat determination section 43, and the number of misfired cylinders determination section 44 in the CPU 40 will be described in more detail with reference to FIGS. I have. FIG. 6 is a flowchart of the ignition timing determination unit 41. As shown in the drawing,
When the engine is started, the ignition timing determination unit 41 starts a cylinder setting counter (step 1) and inputs a pulsar signal from the pulsar coil 12 or 13 (step 2). The ignition order counter 45 counts the ignition order in accordance with the number of cylinders each time a pulser signal is input (1 to 4 in the present embodiment, since there are four cylinders), and stores this count value as a virtual ignition cylinder number ( Step 3). Next, it is determined whether or not a misfire signal has been input from the misfire cylinder number determination section 44 (step 4). If no misfire signal has been input, the ignition coil C1 or C2 to be ignited is determined based on the input pulsar signal, and The timing of outputting the ignition signal is determined from the cycle of the two pulser signals, and the ignition signal is output to the corresponding thyristor 32b or 32c (step 5). If a misfire signal is input at the time of determination in step 4, a virtual ignition cylinder that misfires based on the stored virtual ignition cylinder number (hereinafter, a virtual ignition cylinder that misfires is referred to as a “virtual misfire cylinder”). It is set (step 6). Thereafter, it is determined whether or not the current virtual ignition cylinder is the virtual misfire cylinder set in step 6 (step 7). If the current virtual ignition cylinder is not the virtual misfire cylinder, ignition is performed. A signal is output (step 5). Otherwise, the process returns to step 2 without outputting the ignition signal of step 5. still,
The setting of the virtual misfire cylinder is preferably set so that the misfire timings are set at equal intervals as shown in FIG. 7, but the present invention is not limited to this. The amount can be set arbitrarily according to various conditions such as the amount of the spark plug and the performance of the spark plug. May be set. The processing after step 2 described above is started immediately after the engine is started, and is repeatedly performed until the engine 11 is stopped by operating the stop switch 7 or the like.

FIG. 8 is a main flowchart of the misfiring cylinder number determination section 44. As shown in FIG. 8, first, it is determined whether or not the hydraulic switch 15 is turned on (step 1). When a signal is input from the hydraulic switch 15, it is determined that lubrication is inadequate, and all the cylinders are immediately misfired. A cylinder misfire signal is output (step 10). The misfire of all cylinders is not released until the lubrication failure signal from the hydraulic switch 15 disappears. If the lubrication failure signal is not input from the hydraulic switch 15, it is next determined whether or not the overheat signal is input from the overheat determination unit 43 (Step 2).
1 is determined to be in an overheat state, and an overheat warning control described later is started. The overheat determination in the overheat determination section 43 and the overheat warning control in the misfire cylinder number determination section 44 will be described later in detail, and only the processing of the main flowchart will be described first. If there is no input of the overheat signal in step 2, it is determined whether or not the engine speed Ne input from the engine speed calculation unit 42 is smaller than 6000 rpm (step 3). Here, if the engine speed Ne is smaller than 6000 rpm, the process returns to the overheat signal input determination processing of step 1 again.
If the engine speed Ne is higher than 6000 rpm, then it is determined whether the engine speed is lower than 6100 rpm (step 4). If the engine speed Ne is smaller than 6100 rpm, a one-cylinder misfire signal is output to the ignition timing determination unit 41 (step 5).
If it is larger than 6100 rpm, it is determined whether or not the engine speed Ne is smaller than 6200 rpm (step 6). If it is determined in step 6 that the engine speed Ne is lower than 6200 rpm, a two-cylinder misfire signal is output (step 7). If the engine speed Ne is higher than 6200 rpm, the process proceeds to the next determination process. This determination process is further performed for 6300 rpm (step 8). If the engine speed Ne is smaller than 6300 rpm, a three-cylinder misfire signal is output (step 9). If the engine speed Ne is larger than 6300 rpm, a full-cylinder misfire signal is output (step 1).
0). The above-described processing is repeatedly performed from the time of starting the engine to the time of stopping the engine, whereby, when lubrication failure occurs, all cylinders of the engine 11 are misfired, and
If the engine speed Ne is overspeed of 6000 rpm or more, the engine 11 is misfired in one to four cylinders, and the engine speed is reduced to 6000 rpm or less. As a result, the engine 11 continues to rotate with poor lubrication,
Engine 1 no longer keeps rotating with overspeed
1 is protected.

Finally, regarding the overheat warning control, FIG. 9 is a flowchart of the overheat determination processing in the overheat determination section 43, and FIG. 10 is a graph showing an example of a temperature change in the water jacket. As shown in FIG. 9, the overheat determining unit 43 determines whether the temperature inside the water jacket (hereinafter, sensor temperature) Ts input from the thermosensor 14 at the same time as the start of the engine 11 is equal to or higher than the upper limit temperature Tmax. (Step 1), when the sensor temperature Ts is equal to the upper limit temperature T
If the temperature is equal to or greater than max, it is monitored whether the temperature falls to a predetermined lower limit temperature Tmin or less within a predetermined time t1 (step 2), and as shown by a dashed line in FIG. If the temperature does not drop below the predetermined temperature Tmin within this time, it is determined that an overheat condition has occurred, and an overheat signal is output to the misfiring cylinder number determination unit 44 (step 3). Further, as shown by a solid line in FIG.
When the temperature falls below the lower limit temperature Tmin within the time t1, thereafter, it is continuously monitored whether or not the sensor temperature Ts rises at a speed higher than the predetermined limit temperature rise speed (step 4). As indicated by the two-dot chain line, the sensor temperature Ts
Rises at a speed equal to or higher than the limit temperature rise speed, it is determined that the engine is in an overheat state, and an overheat signal is output to the misfired cylinder number determination unit 44 (step 3). Note that the upper limit temperature Tmax is set higher than a temperature Tlim as a threshold value in general overheating control, for example, a temperature around 85 °, the lower limit temperature Tmin is set lower than the upper limit temperature Tlim, At time t1, after the engine is stopped and the cooling water in the water jacket is drained once, the threshold T
The temperature Ts in the water jacket, which has risen to the upper limit temperature Tmax equal to or higher than lim, is determined by restarting the engine before the temperature is naturally cooled to the threshold Tlim or lower, and when the cooling water is normally supplied into the water jacket. The time is set slightly longer based on the time required to lower the temperature to the lower limit temperature Tmin with the cooling water. With this, when the engine is stopped and the cooling water in the water jacket is completely drained once, and the temperature in the water jacket is high due to the influence of the high-temperature lubricating oil, when the engine is restarted, Even though the cooling water is normally supplied to the water jacket, the temperature in the water jacket heated to the threshold value Tlim or more due to the lubricating oil when the engine is stopped is caused by the trouble of the cooling system, that is, the overheating. There is no misjudgment, and the overheat warning control does not malfunction. The above-described process of the overheat determination unit 43 is repeatedly performed from immediately after the engine 11 starts until the engine 11 stops, as long as the engine 11 does not become overheated.
Is overheated, an overheat signal is output to the misfiring cylinder number determination unit 44, and the process ends.

When the overheat signal is input from the overheat determination unit 43, the misfire cylinder number determination unit 44 performs an overheat warning control process shown in FIG. FIG.
9 is a flowchart of a process during overheat warning control in the misfire cylinder number determination unit 44. In this overheat warning control, misfire cylinders are sequentially increased from one cylinder to four cylinders so that the engine speed Ne does not exceed 2000 rpm (steps 2 to 9). If the engine speed Ne falls to 2000 rpm or less, misfire is reduced to one cylinder. It is stopped one by one (steps 10 and 11). As a result, during the overheating state, the engine speed Ne is 20
00 rpm and the engine 11
Will not rotate at high speed. Although not shown in the flowchart of FIG.
3 outputs a release signal to the misfire cylinder number determination unit 44 when the sensor temperature Ts from the thermo sensor 14 falls below a predetermined overheat state release temperature, and the misfire cylinder number determination unit 44 releases this during the overheat warning control. When the signal is input, the overheat warning control is stopped, and FIG.
It returns to the process of the main flowchart for monitoring the excessive rotation and the lubrication failure shown in (1) (step 1).

(Second Embodiment) Next, a second embodiment of the method for detecting overheating in a marine engine according to the present invention will be described. FIG. 12 is a schematic block diagram of a CPU in an outboard motor ignition control device employing a second embodiment of the overheat detection method in the engine according to the present invention. Note that this outboard motor ignition control device has the first configuration except that there are two types of sensors for detecting overheating and that the processing of the overheating determination unit 43 is different.
Since the configuration is the same as that of the ignition control device of the embodiment, here,
Only parts different in configuration and processing from the first embodiment will be described, and other parts will be assigned the same reference numerals as in the first embodiment, and description thereof will be omitted. As shown in FIG. 13, in the outboard motor on which the outboard motor ignition control device is mounted, a thermosensor 53 is provided near a suction port 52 of a water jacket 51 of the engine 50, and the thermosensor of the water jacket is provided. Downstream of the switch 53, an overheat switch 55 including a bimetal switch or the like whose output switches from OFF to ON at a predetermined temperature is provided. The overheat switch 55 is provided at a place where the cooling water does not react unless at least the cooling water is sufficiently supplied into the water jacket, that is, for example, when the algae or the like adheres to the cooling water suction port of the outboard motor and the amount of the cooling water sucked. Is not zero, but decreases sharply,
A small amount of cooling water is supplied to the vicinity of the suction port 52 in the water jacket 51 and is cooled by the thermosensor 53. However, a place where the cooling water does not flow to the vicinity of the drain port downstream therefrom does not react, Preferably, it is located near the drain 54 of the water jacket 51. The CPU 60 of the control device determines whether or not the engine is in an overheat state by the overheat determination unit 61 based on information input from the two overheat detection sensors (the thermosensor 53 and the overheat switch 55). FIG. 14 shows a flowchart of the determination process in the overheat determination unit 53. As shown in FIG.
Determines whether the temperature inside the water jacket (hereinafter, sensor temperature) Ts input from the thermosensor 53 at the same time as the start of the engine 50 is equal to or higher than a predetermined upper limit temperature Tmax (step 1). Upper limit temperature Tmax
In the above case, it is monitored whether or not the sensor temperature Ts falls below a predetermined lower limit temperature Tmin within a predetermined time t1 (step 2).
If the temperature does not drop below the predetermined temperature Tmin within one, it is determined that an overheat condition has occurred, and an overheat signal is output to the misfiring cylinder number determination unit 44 (step 3). Step 1
If the sensor temperature Ts is lower than the upper limit temperature Tmax at the time of the determination, or if the sensor temperature Ts falls to the lower limit temperature Tmin or less within the time t1 at the determination at the step 2,
It is determined whether or not the overheat switch 55 is ON (step 4).
In the case of N, the suction amount of the cooling water is drastically reduced, it is determined that the cooling water is not sufficiently supplied into the water jacket, an overheat signal is output (step 3), and the overheat switch 55 is turned off. In this case, the process returns to the temperature monitoring state of the thermosensor 53 in step 1 again. As described above, the overheat switch 55 is located downstream of the thermosensor 53 and does not react unless the cooling water is sufficiently supplied into the water jacket, that is, the suction in which the thermosensor 53 is provided. The reaction temperature is set to a value higher than the upper limit temperature Tmax of the thermosensor 53 in step 1 at least because it is located closer to the combustion chamber and higher in temperature than the vicinity of the port 52. Thus, the thermo sensor 53
An overheat switch 55 is provided at least at a location downstream of the water jacket where there is no reaction unless the cooling water is sufficiently supplied into the water jacket, and in addition to the temperature change of the temperature Ts in the water jacket obtained from the thermo sensor 53, By monitoring the state of the switch 55, the judgment immediately after the start of the engine is eliminated, and, for example, algae and the like adhere to the suction port of the cooling water in the outboard motor, and the suction amount of the cooling water is not zero but drastically decreases. ,
A small amount of cooling water is supplied to the vicinity of the suction port 52 in the water jacket 51 and is cooled by the thermosensor 53. However, in the case where the cooling water does not flow to the vicinity of the downstream drain port, it is not overheating. This eliminates the need to make a determination, and provides an effect that the overheat detection is further ensured.

As described above, the overheating judgment process in the case where two overheat detection sensors are provided in the engine is not limited to the above-described embodiment, but may be any judgment process. Specifically, for example, as shown in FIG.
It is determined whether or not s is equal to or higher than a predetermined upper limit temperature Tmax (step 1). If the sensor temperature Ts is equal to or higher than the upper limit temperature Tmax, the sensor temperature Ts is set within a predetermined time t1 within a predetermined lower limit temperature T1. It is monitored whether or not the temperature falls below Tmin (step 2). If the sensor temperature Ts does not fall below the predetermined temperature Tmin within the time t1, it is determined that an overheat condition has occurred, and an overheat signal is output to the misfiring cylinder number determination unit 44. (Step 3) Also, if the sensor temperature Ts is lower than the upper limit temperature Tmax at the time of the determination at Step 1, or if the sensor temperature Ts falls below the lower limit temperature Tmin within the time t1 at the time of the determination at Step 2, Whether the sensor temperature Ts has risen at a speed higher than the predetermined limit temperature rise speed (step 4) and the output of the overheat switch 55 is O If (step 5) may be subjected to a determination process to continue to monitor whether to not become.

(Others) In the embodiment described above, an example is shown in which the overheat detection method according to the present invention is applied to a simultaneous ignition type ignition control device, but this is not limited to this embodiment. Needless to say, the present invention can be applied to any engine control. Further, in this embodiment, the overheat warning control for limiting the engine speed to 2000 rpm by the misfire control when the engine enters the overheat state is performed. However, the control method for protecting the engine after the overheat is detected is described in the present embodiment. Any method may be used without being limited to the example.

[0018]

As described above, the method for detecting overheat in an outboard motor engine according to the present invention comprises providing a temperature detecting means in a water jacket, and detecting a temperature change in the water jacket with the temperature detecting means. Since the overheating of the engine is detected based on the temperature change, even if the inside of the water jacket is heated by the influence of the lubricating oil at the time of starting the engine, the overheating is not determined only from the temperature at that time, and therefore, This has the effect that accurate overheating detection can be performed, so that it is possible to start overheating determination immediately after the engine is started, and it is possible to achieve more complete protection of the engine. Further, according to the overheat detection method according to claim 4,
The temperature detecting means is provided on the inlet side of the water jacket, and the second temperature detecting means is provided on the outlet side of the water jacket, and the temperature on the outlet side of the water jacket detected by the second temperature detecting means is provided. Detection of overheating based on the system enables detection of overheating even in special conditions where algae etc. adhere to the cooling water suction port of the outboard motor and the cooling water suction amount is not zero but drastically decreases Therefore, the effect that the accuracy of overheat detection can be further increased can be achieved.
In addition, by providing two overheat detecting means and detecting the temperature change by one of the detecting means, the temperature change detecting sensor has a relatively low temperature in the water jacket and can be disposed. This has the effect of being able to be provided on the suction port side that is easy.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a boat with an outboard motor equipped with an engine to which an overheat detection method in an outboard engine according to the present invention is applied.

FIG. 2 executes an overheat detection method,
FIG. 4 is a schematic diagram showing a relationship between a wiring structure on the outboard motor side and a wiring structure on the hull including a control device that performs overheat warning control at the time of overheating.

FIG. 3 is a timing chart showing a relationship among a pulsar signal, a soft ignition signal, a hard ignition signal, and an output signal of an ignition signal switching circuit.

FIG. 4 is a schematic diagram showing each processing function of a CPU 40.

FIG. 5 shows a pulser signal, the number of counts of an ignition order counter,
FIG. 4 is a diagram illustrating a relationship among a virtual ignition cylinder number, an actual ignition cylinder, a spark plug to be ignited, and an ignition signal output from an ignition timing determination unit 41.

FIG. 6 is a flowchart of an ignition timing determination unit 41.

FIG. 7 is a diagram showing the relationship between actual ignition cylinders and virtual ignition cylinders and some examples of misfire patterns.

FIG. 8 is a main flowchart of a misfire cylinder number determination unit 44;

FIG. 9 is a flowchart of an overheat determination process in an overheat determination unit 43.

FIG. 10 is a graph showing an example of a temperature change in a water jacket.

FIG. 11 is a flowchart of a process during overheat warning control in the misfired cylinder number determination unit 44.

FIG. 12 is a schematic block diagram of a CPU in an outboard motor ignition control device employing a second embodiment of the method for detecting overheating in an engine according to the present invention.

FIG. 13 is a schematic diagram showing an arrangement position of two overheat detection sensors in an engine.

FIG. 14 is a flowchart of an overheat determination process in an overheat determination unit 61.

FIG. 15 is a flowchart showing yet another embodiment of the overheat determination process.

FIG. 16 shows an example of changes over time in the temperature inside the water jacket, the temperature of the lubricating oil, and the engine speed.

FIG. 17 is a flowchart showing a conventional overheat determination process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outboard motor 2 Hull 3 Handle 4 Seat 5 Throttle / shift lever 6 Main switch 7 Stop switch 8 Meter panel 9 Fuel tank 10 Battery 11 Engine 12 First pulsar coil 13 Second pulsar coil 14 Thermosensor 15 Hydraulic switch 16 Light coil 17 Rectification Constant voltage device 18 Connector 19 Main fuse 20 Ignition power supply circuit 21 Hull power supply circuit 21a Backup circuit 22 Connector 23 Accessory fuse 24 Connector 25 Engine stop circuit 30 Ignition control device 31 Switch circuit 32 CDI circuit 32a Charging capacitor 32b First thyristor 32c Second thyristor 32d Booster circuit 33 Watchdog circuit 34 Constant voltage circuit 35-38 Input circuit 39 Ignition signal switching circuit 40 CPU 41 points Timing determination unit 42 Engine speed calculation unit 43 Overheat determination unit 44 Misfired cylinder number determination unit 45 Ignition order counter P1 First cylinder ignition plug P2 Second cylinder ignition plug P3 Third cylinder ignition plug P4 Fourth cylinder ignition plug C1 First Ignition coil C2 First ignition coil

Claims (4)

[Claims] An overheat detection method for an outboard motor engine that drains cooling water in a water jacket when the engine is stopped and supplies cooling water to the water jacket after the engine starts, comprising detecting temperature in the water jacket. Means for detecting overheating of the engine for an outboard motor, wherein the temperature detecting means detects a temperature change in the water jacket, and detects overheating of the engine based on the temperature change. 2. The overheat detection method for an outboard engine according to claim 1, wherein the temperature change includes a change across a predetermined temperature set in advance. 3. The method for detecting overheating in an outboard engine according to claim 1, wherein the temperature change includes a temperature rising speed at a temperature lower than a predetermined temperature. 4. The water jacket is provided on a suction port side of a water jacket, and a second temperature detection means is provided on a discharge port side of the water jacket, wherein the water jacket detected by the second temperature detection means is provided. The method for detecting overheating in an outboard engine according to any one of claims 1 to 3, wherein overheating is detected based on the temperature of the discharge port side.