JPS62214209A - Stopping device for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent the erroneous operation on start or after start by stopping the operation of an internal combustion engine when the low pressure of lubricating oil continues over a prescribed time and by resetting a low pressure period detecting circuit during the time when the oil high pressure over a prescribed level is detected. CONSTITUTION:A low pressure period detecting circuit 6 detects the period when an oil pressure detecting switch 2 outputs a low pressure signal S1 through a condenser, etc. When the period when the low pressure signal S1 detected by the low pressure period detecting circuit 6 is outputted reaches the previously determined standard period, an oil pressure anomaly detecting circuit 7 outputs a stop signal Sp into a control circuit 4 for the combustion maintenance elements such as fuel valve, etc. A reset circuit 8 keeps the low pressure period detecting circuit 6 in the reset state during the time when the oil pressure detecting switch 2 outputs a high pressure signal S2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention detects an abnormality in oil pressure in lubricating oil of an internal combustion engine using an oil pressure detection switch, and stops the internal combustion engine when an abnormality in oil pressure is detected. It is related to the device.

[Prior art 1] Fig. 4 is an example of a conventional system for detecting abnormalities in lubricating oil of an internal combustion engine caused by lack of lubricating oil, fa lubricating oil leakage, etc. using a hydraulic pressure detection switch and stopping the internal combustion engine. It shows. The conventionally used oil pressure detection switch 2 is in a state where the oil pressure of the lubricating oil of the internal combustion engine 1 is lower than the normal level during normal operation, for example, and detects that the oil pressure is lower than a predetermined level. This switch outputs a low pressure signal indicating the iT1 oil pressure, and when the oil pressure of the iT1 oil becomes higher than the normal level, it becomes an OFF state and outputs a high pressure signal without indicating that the oil pressure is higher than a predetermined level.

The internal combustion engine stop circuit 3 receives a signal output from the oil pressure detection switch 2 and operates a combustion maintenance element 5 that maintains combustion in the internal combustion engine, such as a fuel valve of a diesel engine, an ignition power source for an ignition device, or a capacitor discharge type. This disables the ignition energy storage capacitor of the ignition system. That is, the internal combustion engine stop circuit 3 outputs a stop signal to the combustion sustaining element control circuit 4 that controls the combustion sustaining element 5, and stops the operation of the internal combustion engine when the oil pressure detection switch 2 detects an abnormality in the oil pressure. .

[Problems to be Solved by the Invention] As described above, the oil pressure detection switch 2 is configured to output a low pressure signal until the oil pressure of the lubricating oil reaches a predetermined level. A low pressure signal is output until the oil pressure of the oil reaches a predetermined level. Therefore, when the engine is started, if the output of the oil pressure detection switch 2 is input as an input signal to the internal combustion engine stop circuit 3 before the engine rotation reaches a predetermined value, the state of the lubricating oil is normal. However, there is a problem in that the internal combustion engine stop circuit 3 outputs a stop signal to the combustion sustaining element control circuit 4. Therefore, in the conventional internal combustion Ia engine stop device, the output of the oil pressure detection switch 2 is set to the internal combustion engine until the rotation speed detection circuit detects the rotation speed of the internal combustion engine and the rotation speed detection circuit detects a predetermined rotation speed. A complicated circuit was provided to prevent the signal from being input to the stop circuit 3. Therefore, conventional devices have complicated configurations,
In addition, the cost of the device is high, and it is necessary to match the rotational speed of the engine, so there is a problem that it is difficult to make the device versatile.

In addition, even under normal operating conditions, when extremely strong vibrations are applied to the oil pressure detection switch, or when the lubricating oil is not completely lacking in ω, but is about to run out, the oil pressure detection switch 2 may temporarily output a low voltage signal.

However, in the conventional device, no measures are taken to prevent malfunction after the engine starts FIJ, so even if the oil pressure detection switch 2 temporarily outputs a low pressure signal, a stall signal is output. There was a risk.

The purpose of this defense is to detect an internal combustion engine that solves the above problems by detecting the period during which the oil pressure detection switch outputs a low pressure signal without detecting the engine speed, and by utilizing this detected period. 12 stop devices are provided.

[Means for solving problem j; 1] In order to solve the above-mentioned problems, the present invention solves the problems described above, as shown in FIG. 1 showing an embodiment of the present invention. When this is detected, the internal combustion engine stop device outputs a stop signal to the combustion sustaining element control circuit 4 of the combustion sustaining element 5 that maintains combustion in the internal combustion engine, disables the combustion sustaining element 5, and stops the internal combustion engine. an oil pressure detection switch 2 that detects the oil pressure of the oil pressure, outputs a low pressure signal when the oil pressure is below a predetermined level, and outputs a high pressure signal when the oil pressure is higher than the predetermined level; 1IllI? to which the low voltage signal detected by the low voltage period detection circuit 6 is output. The oil pressure abnormality detection circuit 7 outputs a stop signal to the combustion maintenance element control circuit 4 when Sl reaches a predetermined reference period, and the low pressure period detection circuit 6 is reset while the oil pressure detection switch 2 outputs a high pressure signal. It consists of a reset circuit that maintains the

[Operation of the Invention] According to the present invention, the low pressure period detection circuit 6 detects the period during which the oil pressure detection switch 2 outputs the low pressure signal, and only when this period reaches a predetermined reference period, The hydraulic pressure abnormality detection circuit 7 outputs a stop signal to the combustion maintenance element control circuit 4 upon determining that the oil pressure detection switch 2 is outputting a low pressure (i+gb<lubricating oil oil pressure abnormality).

Even if the oil pressure detection switch 2 outputs a low pressure signal, if the output period is short, the reset circuit 8 puts the low pressure period detection circuit 6 into the reset state.
The oil pressure abnormality detection circuit 7 does not determine that there is an oil pressure abnormality.

Therefore, by simply setting the base 1% brightness to the 1111 required for the engine to reach its normal rotational speed depending on the type of engine, a versatile internal combustion engine stopping device can be provided with a simple configuration. can.

Furthermore, during normal operation, even if the oil pressure detection switch 2 temporarily generates low pressure No. 13 for some reason even though there is no shortage of lubricating oil, according to the present invention, a stop signal is immediately generated. This prevents malfunctions after the engine is started.

[Examples] Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the basic configuration of an embodiment of an internal combustion engine stop system using the present invention. In this figure, the same parts as those in the stop system shown in FIG. 4 are given the same reference numerals as the members shown in FIG. 4.

In the embodiment shown in FIG. 1, reference numeral 6 denotes a low pressure period detection circuit that detects a period during which the oil pressure detection switch 2 outputs the low pressure signal S1. This period may be detected by, for example, charging the capacitor, and various other known period detection circuits may be used.

7 is a low voltage signal 8 detected by the low voltage period detection circuit 6
This is a hydraulic abnormality detection circuit that outputs a stop signal Sp to the combustion maintenance element control circuit 4 when the period during which 1 is output reaches a predetermined reference period. Reference numeral 8 denotes a reset circuit that maintains the low pressure period detection circuit 6 in a reset state, that is, maintains the function of the low pressure period detection circuit 6 in a stopped state while the oil pressure detection switch 2 outputs the high pressure signal S2.

This embodiment further includes a control circuit reset circuit 9 that resets the combustion sustaining element control circuit 4 that performs an operation of deactivating the combustion sustaining element 5 upon receiving a stop signal. This control circuit reset circuit 9 does not need to keep the combustion sustaining element control circuit 4 in an operating state after urn has stopped, so a predetermined period of time has elapsed since the combustion sustaining element control circuit 4 started operating. This circuit is for setting the combustion sustaining element control circuit 4 to a reset state after the combustion maintenance element control circuit 4 is reset. Use of this control circuit reset circuit 9 has the advantage of preventing wasteful power consumption. Note that this control circuit reset circuit 9 is not necessarily a necessary requirement for constructing the apparatus of the present invention.

FIG. 2 shows a specific circuit of an embodiment of the present invention in which the fuel valve of a diesel engine is used as a combustion sustaining element. The member indicated by the symbol B in FIG. 2 is a battery that is charged by a generator that generates electric power in synchronization with the rotation of an internal combustion engine (not shown), and this battery B constitutes the power source for the entire stopping device. It is. One end of a key switch SW, which is closed when the engine is started, is connected to the non-grounded terminal of battery B. The other end of the key switch SW is connected to the anode of a diode D1 for preventing backflow, one end of a solenoid coil L that controls opening and closing of a fuel valve (not shown), and a diode D2 connected in parallel to both ends of the solenoid coil L. is connected to the cathode of

In this embodiment, the reset circuits 1 to 8 include a resistor R1 whose one end is connected to the cathode of the diode D1, and a resistor R1.
A capacitor C1 is charged via a capacitor C1 whose base is a resistor R
1 and a transistor Tr1 connected to the connection point of the capacitor C1 and whose emitter is grounded. and,
The output terminal of the oil pressure detection switch 2 is connected to the connection point between the resistor R1 and the capacitor C1. In this embodiment, as shown in the figure, when the switch 2 is in the OFF state, it is when the oil pressure of the lubricating oil is higher than a predetermined level. Furthermore, when the oil pressure of the lubricating oil is below a predetermined level, such as when starting the engine or when there is a shortage of lubricating oil, the oil pressure detection switch 2 is turned on. In this embodiment, when the oil pressure detection switch 2 is in the on state and the output terminal 2a of the switch 2 is equal to the ground potential, the switch 2 is considered to be outputting a low pressure signal, and when the switch 2 is in the off state, the switch 2 is output. It is assumed that the switch 2 outputs a pressure signal when a predetermined voltage is applied to the terminal 2a of the switch 2.

The low voltage II detection circuit 6 includes a resistor R2, one end of which is connected to the cathode of the diode D1, and a capacitor C2, which is connected in series with the resistor R2 and is charged from the battery B through the resistor R2.

Resistor R2 and capacitor C2 constitute a general delay circuit. Charging of capacitor C2 is performed using oil pressure detection switch 2.
is on when the lubricating oil level is below a predetermined level. When the oil pressure detection switch 2 is in the OFF state, a current flows through the resistor R1 to the base of the 1-transistor Tr1 and the transistor Tr1 becomes conductive, so that the capacitor C2 is not charged. therefore,
The charging time or charging voltage of the capacitor C2 changes in accordance with the ON time of the oil pressure detection switch 2. The low pressure period detection circuit 6 indicates the period during which the oil pressure detection switch 2 outputs a low pressure signal from the ON state by the charging II pressure of the capacitor C2.

The hydraulic abnormality detection circuit 7 includes a reference voltage generation circuit consisting of a voltage dividing circuit of a resistor R3 and a resistor R4, a terminal voltage Vc2 of a capacitor C2 is inputted to one input terminal, and the voltage is divided by a resistor R3 and a resistor R4 to one terminal. an operational amplifier zopi to which the reference voltage vr,1 is input, a diode D3 whose cathode is connected to the output of the operational amplifier OP1, and a diode D.
It is composed of a diode D4 whose anode is connected to the anode of No. 3, and a resistor R5.

Operational amplifier OP1 has input voltage Vc2 as reference voltage Vr1.
When it becomes larger, a high level signal is output and the input voltage V
When c2 is smaller than the reference voltage Vr1, a low level signal, that is, a ground potential signal is output. When a high level signal is output from operational amplifier OP1, battery B-g anti-R5→
A current flows through the path from the diode D4 to the base of the transistor Tr2. The signal supplied to the base of the transistor Tr2 at this time constitutes a stop signal.

The reference voltage Vr1 is determined by whether the time required for the charging voltage of the capacitor C2 to reach the reference voltage ■r1 is equal to the time required for the oil pressure of the lubricating oil of the engine to which this device is applied to reach a predetermined level after the engine is started, or It is set to be longer than that. Therefore, in this embodiment, the reference voltage generation circuit composed of the resistor R3 and the resistor R4 functions to determine the reference period, and the reference voltage V
r1 corresponds to the early period.

The combustion sustaining element control circuit 4 includes a transistor Tr2 whose base is connected to the cathode of the diode D4 of the hydraulic abnormality detection circuit 7 and whose emitter is grounded and a capacitor C3. The solenoid coil is connected to the anode of diode D2.

The control circuit relet circuit 9 includes a delay circuit having one end connected to the diode D1 and comprising a resistor R6 and a capacitor C4 charged via the resistor R6, and a reference voltage comprising a voltage dividing circuit comprising a resistor R7 and a resistor R8. a generating circuit, an operational amplifier OP2 to which the base tv=voltage Vr2 is input from the connection point of the resistor R7 and the resistor R8 to one input terminal, and the terminal voltage Vc4 of the capacitor (condenser) J-04 is input to one input terminal, and the resistor R
6 and a capacitor C4, and a diode D5 whose anode is connected to the other end of the resistor R9 and whose cathode is connected to the output terminal of the operational amplifier OPI. The output of the operational amplifier ZOP2 is connected to the input terminal of the combustion sustaining element control circuit 4.

The capacitor C4 is connected to the operational amplifier O of the hydraulic abnormality detection circuit 7.
While the output of P1 is at a low level, that is, while the oil pressure of the lubricating oil is detected to be normal, it is rarely charged. When the terminal voltage VC4 of the capacitor C4 becomes 5 times higher than the viscosity voltage vr2, the operational amplifier OP2 outputs a ground potential signal from the low level signal section to its output. :Yamakui amplifier OP2 has terminal voltage V of capacitor C4.
c4 is base IX! It is configured so that no output is generated when the voltage is less than r2. Therefore, the control circuit reset circuit 9 does not operate unless the voltage abnormality detection circuit 7 detects an abnormality in the oil pressure and a high level signal is not outputted to the output of the operational amplifier OP1.

Next, the operation of the above circuit will be explained. Since the oil pressure of the lubricating oil is below a predetermined level, the oil pressure detection switch 2 is in an on state until the engine rotation reaches a predetermined rotation speed, for example, an idling rotation speed after the engine is started. Therefore, when the key switch SW is closed to start the engine, a current flows through the path from the battery B to the switch SW to the diode D1 to the resistor R2 to the capacitor C2, and the capacitor C2 is charged. Capacitor C
The charging voltage VC2 of 2 is the 8 of resistor R2 and capacitor C2.
It increases according to a time constant determined by the mother.

Assuming that there is a shortage of lubricating oil, the oil pressure detection switch 2 remains on even if the engine rotation reaches a predetermined rotation speed. Therefore, the terminal voltage VC2 of the capacitor C2 continues to rise because the transistor Trl that discharges the charge of the capacitor C2 does not conduct. Charging voltage V
C2 is the MQ voltage Vr1 determined by resistor R3 and resistor R4
If it becomes larger, operational amplifier OP1 will generate a high level output.

When the terminal voltage VC2 is lower than the reference voltage Vrl, the output of the operational amplifier OP1 is at a low level, that is, the ground potential, so the battery B → key switch SW → diode D1 →
A current flows through the path of resistor R5→diode D3→operational amplifier OP1.

Therefore, in this case, since no base current flows through the transistor Tr2 and no current flows through the solenoid coil L, the fuel valve (not shown) remains open, and combustion in the engine is maintained. At this time, since current also flows through the path of diode D1 → resistor R6 → resistor R9 → diode D5 → operational amplifier OP1, capacitor C4 of control circuit reset circuit 9 is hardly charged.

Therefore, in this state, the control circuit reset circuit 9 does not operate.

When the voltage Vc2 of the capacitor C2 becomes larger than the reference voltage Vr1 and the output j of the operational amplifier OP1 becomes a high level, the resistance R5→diode D4→transistor Tr
Current flows through the base-emitter circuit path of No.1. Therefore, 1 to transistor l'-rl are conductive and the solenoid
Excitation 11 current flows through the coil, a fuel valve (not shown) is closed, and the engine is stopped. Therefore, the time it takes for the terminal voltage Vc2 of the capacitor C2 to reach the reference voltage ■r1 is 115 when the engine rotation speed increases to a predetermined rotation speed or more and the oil pressure reaches a predetermined level when the lubricating oil is properly pumped. resistor R2 so that it is somewhat longer than the
and the capacitance of condenser→noC2 are appropriately selected and determined.

When the output of the amplifier OP1 reaches a high level, a current flows through the path of battery B → switch SW → diode D1 → resistor R6 → capacitor C4, and the terminal voltage Vc4 of capacitor C4 increases from resistor R6 and capacitor C4. 1 arm according to the time constant determined by and. Condens It C4
When the terminal voltage VC4 of the operational amplifier OP becomes larger than the reference voltage Vr2 determined by the resistor R7 and the resistor R8, the operational amplifier OP
The output of transistor Tr2 becomes low level and bypasses the base current input to the base of transistor Tr2. therefore,
After a delay time determined by a delay circuit including a resistor R6 and a capacitor C4, the transistor Tr2 is cut off, which prevents unnecessary power consumption and also prevents the battery from running out. This delay time is from the time when the fuel valve is closed.
Set the time enough for the engine to completely stop.

If there is enough lubricating oil, the oil pressure of the lubricating oil will reach a predetermined level before the terminal voltage Vc2 of capacitor C2 reaches the reference voltage Vr1 after the key switch is closed and the engine starts. Detection switch 2
turns off, and transistors 1 to Tr1 become conductive.

When the transistor Trl becomes conductive, the charge in the capacitor C2 is discharged through the collector-emitter circuit of the transistor Tr2. Therefore, when the oil pressure of the lubricating oil is normal, the output of the operational amplifier OP1 is maintained at a low level, so the transistor Tr2 is not turned on and the solenoid coil L is not energized, and the engine is stopped. Continue normal operation without any problems.

Even if there is no shortage of lubricating oil, if extremely strong vibrations are applied to the engine or if lubricating oil is approaching a state of insufficient lubricating oil, the oil pressure detection switch 2 will temporarily turn on. It may happen. However, even if the oil pressure detection switch 2 is temporarily turned on, the period in which it is turned on is short, so the capacitor C
2-9η: Before the child voltage Vc2 becomes larger than the reference voltage ■r1, the oil pressure detection switch 2 is turned off again, the transistor Tr1 becomes conductive, and the charge in the capacitor C2 is discharged. Therefore, even if the oil pressure detection switch 2 is temporarily turned on for some reason when there is no shortage of lubricating oil, it is possible to reliably prevent the internal combustion period stop device from malfunctioning.

In the above embodiment, if a light emitting diode is used instead of the diode 16 and used as a warning lamp for the operator, it is possible to display to the operator that the cause of the stoppage of the internal combustion period is a lack of lubricating oil.

In the above embodiment, the fuel valve of the diesel engine is controlled to stop the engine, but the present invention is not limited to the above embodiment. Of course, the ignition energy storage capacitor or the like of the capacitor discharge type internal combustion engine ignition device may be short-circuited to stop the ignition operation of the ignition device and stop the engine.

FIG. 3 shows an embodiment in which the present invention is applied to the case where the exhaust I nighter coil EX as the ignition power source of the capacitor discharge type ignition device 10 is short-circuited to stop the internal combustion engine. This embodiment has the same configuration as the embodiment shown in FIG. 2, except that the configuration of the combustion sustaining element circuit 4 and the combustion sustaining element 5 are different. In this embodiment, a thyristor SCR1 capable of short-circuiting high output is used in place of the 1-transistor Tr2 of the combustion sustaining element control circuit 4 shown in FIG.

The capacitor discharge type ignition device 10 includes an ignition coil P and 1
3. An ignition energy storage capacitor C10 provided on the primary side of the ignition coil P, a discharge control thyristor scr<io that conducts at the ignition timing and discharges the charge of the °C capacitor C10 through the primary coil of the ignition coil P, and an internal combustion The thyristor 5CR10 is a well-known circuit consisting of an exciter coil EX disposed in a magnet generator driven by the engine, and a diode D10 that half-wave rectifies the output of the exciter coil. It has a l-ring and is conductive all the way through.

The capacitor CIO is charged to the polarity shown in the figure through the output of the exhaust coil EX and the re-diode D10. When the Lee Iristor S CR10 becomes conductive at the ignition timing, the charge of the capacitor C10 becomes 1 Nyristor 5CR10.
A discharge occurs through the primary coil of the ignition coil P, and a high voltage for ignition is induced in the secondary coil.

In the present embodiment 43, the anode of the thyristor sCR'l of the combustion sustaining element control circuit 4 is connected to the connection point between the exciter coil EX and the diode DIO. Therefore, when the stop signal output from the hydraulic abnormality detection circuit 7 is supplied to the gate of the thyristor scr+i and the thyristor 5CR1 becomes conductive, the exciter coil EX is short-circuited, so the ignition operation is stopped and the engine is stopped.

The thyristor 5CR1 continues to operate until no voltage is induced in the exciter coil [X] until the output of the control circuit reset circuit 9 becomes a low level or the engine stops and no voltage is induced in the exciter coil EX in the direction of the arrow shown. The output of the exciter coil EX is short-circuited each time the exciter coil EX is turned on. Therefore, the control circuit reset circuit 9 outputs an output of 11 when the engine rotation is reduced to 11 so that the output of the equalizer EX is no longer able to store sufficient ignition energy in the capacitor C10. Vessel OP
The output of 2 is set to be low level.

In the above embodiment, in order to short-circuit the night coil EX by the thyristor 5CR1, the capacitor C10, the primary coil of the ignition coil, or the discharge control thyristor scr<io's 1- Of course, the ignition operation may be stopped by short-circuiting the power swords.

In the above embodiment, the battery is used as the power source for the device, but it goes without saying that the output of the generator driven by the internal combustion engine may be rectified by a rectifier, and the output of the rectifier may be used as the power source.

[Effects of the Invention] According to the present invention, the low pressure period detection circuit detects the period during which the oil pressure detection switch outputs the low pressure signal, and only when this period reaches a predetermined reference period, the oil pressure is The abnormality detection circuit outputs a stop signal to the combustion maintenance element control circuit,
Even if the oil pressure detection switch outputs a low pressure signal, if the output period is short, the oil pressure abnormality detection circuit will not output a stop signal because the reset circuit puts the low pressure period detection circuit into the reset 1-state. Therefore, according to the present invention, a simple configuration is possible without using a complicated circuit for detecting the rotation speed of the internal combustion engine and keeping the oil pressure detection switch in an invalid state until the engine rotation speed reaches a predetermined value. It is possible to configure an internal combustion immediate stop device. In addition, in the present invention, since there is no need to directly match the rotation speed of the internal combustion engine, the reference period can be simply set to the period required for the engine rotation to reach the normal rotation speed depending on the type of engine. It is possible to provide a versatile internal combustion-like open/stop device with a simple configuration. Furthermore, according to the present invention, even if the oil pressure detection switch temporarily generates a low pressure signal for some reason during normal operation, a stop signal is not generated immediately, which prevents malfunction after the engine is started. It can be prevented.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a schematic configuration of an embodiment of a device using the present invention, Fig. 2 is a circuit diagram showing an embodiment of the invention when stopping a diesel engine, and Fig. 3 is a circuit diagram showing an embodiment of the invention when stopping a diesel engine. FIG. 4 is a circuit diagram showing another embodiment of the present invention in the case of a stoppage, and FIG. 4 is a block diagram without showing the outline of a production system using an oil pressure detection switch. 1... Internal combustion engine, 2... Oil pressure detection switch, 4...
- Combustion maintenance element control circuit, 5... Combustion maintenance element, 6.
...Low pressure period detection circuit, 7...Hydraulic pressure abnormality detection circuit, 8
...Reset circuit, 9...Circuit to control circuit reset 1. Procedure No. 111 Official Book (Method) June 4, 1986 Special Patent 1.1 Director General of the Agency 1, Indication of Case Patent Application No. 111-53596 2, Name of Invention Internal Combustion Engine Stopping Device 3 , Relationship to each case to be amended Patent applicant (134) Kokusan Denki Co., Ltd. 4, Agent 5, 6th floor, Bunzan Building, 4-31-6 Shinbashi, Minato-ku, Tokyo Date of amendment order: May 27, 1986 6. Column 7 of "Brief explanation of drawings" of the specification subject to amendment, Contents of amendment

Claims (5)

[Claims] (1) When it is detected that there is an abnormality in the oil pressure of the lubricating oil of the internal combustion engine, a stop signal is output to the combustion maintenance element control circuit that controls the combustion maintenance element that maintains combustion in the internal combustion engine, and the combustion maintenance element is disabled. An internal combustion engine stopping device for stopping an internal combustion engine by detecting the oil pressure of the lubricating oil, outputting a low pressure signal when the oil pressure is below a predetermined level, and outputting a high pressure signal when the oil pressure is higher than the predetermined level. An oil pressure detection switch to output, a low pressure period detection circuit that detects a period during which the oil pressure detection switch outputs the low pressure signal, and a period during which the low pressure signal detected by the low pressure period detection circuit is output is determined in advance. an oil pressure abnormality detection circuit that outputs the stop signal to the combustion maintenance element control circuit when a predetermined reference period is reached, and maintains the low pressure period detection circuit in a reset state while the oil pressure detection switch outputs the high pressure signal. An internal combustion engine stop device comprising a reset circuit. (2) The oil pressure detection switch turns on when the oil pressure is below the predetermined level and outputs the low pressure signal to the output terminal, and turns off when the oil pressure becomes higher than the predetermined level. The internal combustion engine stopping device according to claim 1, wherein the high voltage signal is output to an output terminal. (3) The low-pressure period detection circuit includes a delay circuit including a capacitor that is charged by the battery voltage via a resistor during the period when the oil pressure detection switch outputs the low-pressure signal. The internal combustion engine stopping device according to claim 1, further comprising detecting a period during which the low pressure signal is output. (4) The oil pressure abnormality detection circuit includes a reference voltage generation circuit that outputs a reference voltage corresponding to the reference period, and a comparison circuit that compares the reference voltage and the charging voltage of the capacitor, and the charging voltage The internal combustion engine stop device according to claim 3, wherein the stop signal is output when the voltage exceeds the reference voltage. (5) The reset circuit includes a discharging transistor switch that conducts the high voltage signal from the oil pressure detection switch as a conduction signal to discharge the charge in the capacitor. The internal combustion engine stop device according to item 3.