JPH11270323A - Alarm method and device for oil pressure drop of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use an alarm device for oil pressure drop in common for a plurality of kinds of engine by detecting oil pressure of the engine, and in the case where the detected oil pressure is lower than the lowest oil pressure predetermined on the basis of the water temperature of the engine and the engine speed, outputting the alarm signal for showing abnormality of the engine. SOLUTION: When an engine is started and a power source is closed, a micro computer 17 reads the water temperature signal from a water temperature sensor 10, and diagnoses abnormality of the water temperature sensor 10. Namely, the micro computer 17 reads the rotating signal from a rotation sensor 14, and sets the lowest oil pressure corresponding to the water temperature signal and the engine speed signal from a lowest oil pressure memory 15. The micro computer 17 read the oil pressure signal from an oil pressure sensor 12, and compares the real oil pressure with the lowest oil pressure. In the case where the real oil pressure is larger than the lowest oil pressure, the micro computer 17 judges normal drive of the engine, and on the other hand, in the case where the real oil pressure is smaller than the lowest oil pressure, the micro computer 17 judges abnormality of the engine, and the micro computer 17 outputs the alarm signal to an alarm lamp 18 for lighting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for warning a decrease in engine oil pressure, which gives an alarm when the oil pressure of the engine drops abnormally.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram showing a configuration of a conventional engine oil pressure drop warning device. The microcomputer 4 inputs a rotation speed signal from a rotation sensor 1 that detects the rotation speed of the engine, and converts an oil pressure signal (hereinafter, referred to as actual oil pressure) from a hydraulic pressure sensor 2 that detects the oil pressure of the engine into an A / D converter. The minimum oil pressure is read from the memory 7 and is compared with the oil pressure detected by the oil pressure sensor 2. If the oil pressure falls below, for example, as shown in FIG. 6, when the rotation speed is in the range of N1 to N2, the engine oil pressure detected by the oil pressure sensor 2 is read, and the minimum oil pressure P1 corresponding to the engine oil pressure is read. By making a comparison, a warning signal is created, and the warning means 5 such as a warning lamp and a buzzer is driven, and the actuator 6 is driven to stop the engine. . The minimum oil pressure is P1 when the rotation speed is in the range of N1 to N2, and P1 when the rotation speed is in the range of N2 to N3.
2. P3 when the rotation speed is in the range of N3 to N4, P4 when the rotation speed is in the range of N4 to N5, and N5 to N
In the case of the range of 6, it is P5.

[0003]

However, when such a conventional low oil pressure warning device for an engine is mounted on various engines, the rotational speed / oil pressure characteristics for each type of engine shown in FIG. In order to have the characteristic that changes within the range A shown, the minimum oil pressure must be set lower in accordance with the engine showing the lowest engine oil pressure at a predetermined rotation speed, and a sufficient margin must be provided. There have been problems such as the inability to reliably issue an alarm.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an engine oil pressure drop warning method and apparatus which can be used in common for a plurality of types of engines.

[0005]

According to a first aspect of the present invention, there is provided a method for alarming a decrease in oil pressure of an engine, wherein the oil pressure of the engine is detected, and the minimum oil pressure determined in advance based on the water temperature and the number of revolutions of the engine is detected. In comparison with the hydraulic pressure, when the detected hydraulic pressure is lower than the minimum hydraulic pressure, an alarm signal indicating an engine abnormality is output.

[0006] An engine oil pressure drop warning device according to a second aspect of the present invention includes a water temperature sensor for detecting the temperature of engine cooling water, a hydraulic sensor for detecting oil pressure of lubricating oil of the engine, and a rotational speed of the engine. A memory that stores the rotation sensor to be detected, the number of rotations of the engine, the temperature of the cooling water, and the corresponding minimum oil pressure in association with each other, and detection from each of the water temperature sensor, the oil pressure sensor, and the rotation sensor Inputting an output, reading the minimum oil pressure corresponding to the input detection outputs from the water temperature sensor and the rotation sensor from the memory, comparing the minimum oil pressure with the oil pressure from the oil pressure sensor, and comparing the oil pressure from the oil pressure sensor with the oil pressure from the oil pressure sensor. Is lower than the minimum oil pressure, an alarm signal indicating an engine abnormality is output.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 An embodiment according to the present invention will be described with reference to FIG. Reference numeral 10 denotes a water temperature sensor for detecting the temperature of the cooling water of the engine, 11 denotes a first A / D converter for converting an analog water temperature signal from the water temperature sensor 10 into a digital signal, 12 denotes a hydraulic pressure sensor for detecting the oil pressure of the engine, 13 Is a second A / D for converting an analog hydraulic signal from the hydraulic sensor 12 into a digital signal.
The converter 14 is a rotation sensor for detecting the engine speed.

Reference numeral 15 denotes a minimum hydraulic pressure memory for storing minimum hydraulic pressure data in the form of a table. For example, as shown in FIG. 2, the horizontal axis represents the engine water temperature and the vertical axis represents the engine speed. The minimum oil pressure of the engine determined by the water temperature and the engine speed is stored. Note that the lowest oil pressure in FIG.
When the rotation speed is between 0 and T1 and the rotation speed is between N0 and N1, the minimum hydraulic pressure is set to A1, the water temperature is T1 and T2, and the rotation speed is N1 and N1.
In the case of N2, the minimum oil pressure is B2 and the water temperature is T2-T.
3. When the rotation speed is between N2 and N3, the minimum oil pressure is C
3. When the water temperature is between T3 and T4 and the rotation speed is between N3 and N4, the minimum oil pressure is set to be D4.

Reference numeral 16 denotes a water temperature memory, and the water temperature sensor 10
Is stored for each detected water temperature in a permissible range with respect to the detected water temperature.
When a water temperature signal is supplied from 7, a reference water temperature indicating an allowable range for the water temperature signal is supplied to the microcomputer 17.

The microcomputer 17 includes the first A
A water temperature signal from the water temperature sensor 10 is input via the / D converter 11, and a rotation signal of the engine is input from the rotation sensor 14, and the water temperature signal and the rotation signal are supplied to the minimum hydraulic memory 15. The minimum oil pressure corresponding to the water temperature signal and the rotation signal is read from the minimum oil pressure memory 15. For example, in FIG.
If the rotation speed is N3 to N4, the minimum oil pressure D4 is read.

The microcomputer 17 comprises:
Only when the microcomputer 17 starts to operate, input a reference water temperature corresponding to the input water temperature signal to the water temperature memory 16 and, if the temperature does not deviate from the allowable reference water temperature within the predetermined time, Creates an alarm signal indicating that the water temperature sensor 10 is exposed to the air and leaks cooling water, and drives the alarm lamp 18.

Further, the microcomputer 17
Is the hydraulic pressure signal from the hydraulic pressure sensor 12 read via the second A / D converter 13 and the minimum hydraulic pressure memory 1
If it is determined that the oil pressure signal is smaller than the minimum oil pressure as compared with the minimum oil pressure from No. 5, the engine lubrication oil is missing or insufficient, and if the engine continues to operate as it is, the engine will burn. It is determined that there is a risk of being destroyed, and the alarm means 18 is driven.
The engine 19 is driven to stop the engine.

Next, the operation of the above configuration will be described below with reference to the flowcharts shown in FIGS. That is, when the power is turned on, the process proceeds from step 100 to step 110, where the microcomputer 17 reads the water temperature signal from the water temperature sensor 10 and proceeds to step 1
Proceeding to 20, the program jumps to a subroutine shown in FIG. 4 and described later to perform an abnormality diagnosis of the water temperature sensor 10, and returns to step 130 in FIG. 3 when each step shown in FIG. 4 ends. In step 130, the rotation signal from the rotation sensor 14 is read, and in step 140, the minimum oil pressure corresponding to the water temperature signal and the rotation speed signal read in step 110 from the minimum oil pressure memory 15 is read.

At step 150, a hydraulic signal indicating the hydraulic pressure is read from the hydraulic pressure sensor 12 and the next step 160 is executed.
Then, the read actual oil pressure (the signal from the oil pressure sensor 12) is compared with the minimum oil pressure. If the actual oil pressure is larger than the minimum oil pressure, it is determined that the engine is normally driven, and step 170 is performed. Then, a count value N described later is reset to 0, and the process returns to step 110.

If the actual oil pressure is smaller than the minimum oil pressure in step 160, it is determined that an oil leak has occurred and the engine is abnormal, and the routine proceeds to step 180, in which a counter function is operated and N is set to one. The above steps 110 to 180 are repeatedly executed until the counted value N exceeds, for example, 100 in step 190. When the counted value N exceeds 100, the process proceeds to step 200, where an engine stop signal is output to the actuator 19, and At 210, an alarm signal is output to the alarm lamp 18 and the process is terminated.

Next, the subroutine shown in FIG. 4 will be described. That is, in step 10, the water temperature sensor 10
Is set as the initial actual water temperature (the signal from the water temperature sensor 10) immediately after the start of the engine (including immediately after a certain time immediately after the start of the engine) detected in the step S20. 16 to the allowable value T1 for the reference water temperature corresponding to the set actual water temperature.
T2 is read, and in step 30, the allowable range T1
If it is determined that it is in T2, it is determined that the water temperature sensor 10 is normal, the process proceeds to step 40, and returns.
If it is determined in step 30 that the temperature does not fall within the allowable range T1 to T2, the alarm lamp 17 is driven in step 50 as a cooling system abnormality or insufficient cooling water, and the process proceeds to step 40.

[0017]

As described above, according to the present invention, oil leakage from the engine can be easily detected only by adding a simple structure, that is, adding a water temperature sensor. Further, the effect that the engine can be attached to engines of other displacements only by changing the storage contents of the memory is exhibited.

[Brief description of the drawings]

FIG. 1 is an electric circuit block diagram showing an engine oil pressure drop warning device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining minimum hydraulic pressure data stored in a minimum hydraulic pressure memory 15 shown in FIG. 1;

FIG. 3 is a flowchart for explaining the operation of the microcomputer of FIG. 1;

FIG. 4 is a diagram showing a subroutine for a main flowchart of the microcomputer of FIG. 3;

FIG. 5 is a block diagram showing a conventional engine oil pressure drop warning device.

FIG. 6 is a graph showing a hydraulic curve for explaining the operation of the microcomputer in FIG. 5;

[Explanation of symbols]

 Reference Signs List 10 water temperature sensor 11, 13 A / D converter 12 oil pressure sensor 14 rotation sensor 15 minimum hydraulic memory 16 water temperature memory 17 microcomputer 18 alarm lamp 19 actuator

Claims (2)

[Claims] 1. An oil pressure of an engine is detected, and a minimum oil pressure determined in advance based on a water temperature and a rotation speed of the engine is compared with the detected oil pressure.
A low oil pressure warning method for an engine, comprising: outputting an alarm signal indicating engine abnormality when the oil pressure is lower than a minimum oil pressure. 2. A water temperature sensor for detecting a temperature of cooling water of the engine, a hydraulic pressure sensor for detecting a hydraulic pressure of lubricating oil of the engine, a rotation sensor for detecting a rotation speed of the engine, a rotation speed of the engine, A memory that stores the temperature of the cooling water in association with the corresponding minimum hydraulic pressure, and detection outputs from the water temperature sensor, the hydraulic pressure sensor, and the rotation sensor, and inputs the input water temperature sensor and rotation. The minimum oil pressure corresponding to the detection output from the sensor is read from the memory, and the minimum oil pressure is compared with the oil pressure from the oil pressure sensor.If the oil pressure from the oil pressure sensor is lower than the minimum oil pressure, an engine abnormality is detected. A warning signal indicating a decrease in oil pressure of the engine, which outputs a warning signal indicating the warning.