JP2013044277A - Oil level detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil level detection device that surely detects a drop in the level of oil stored in an oil storage means with an inexpensive configuration.SOLUTION: The oil level detection device 30 is configured to detect a drop in oil level on the following condition. A signal processing circuit 32 detects the amount of oil mist in a crank chamber 16 of an engine 1 on the basis of the high frequency component of a pressure detection value in the crank chamber 16. An ECU 33 detects a drop in oil level on the condition that the pressure value of the high frequency component of the pressure variation in the crank chamber 16 is below the predetermined threshold.

Description

  The present invention relates to an oil level detection device, and more particularly to an oil level detection device that detects an oil level stored in an oil storage means of an internal combustion engine.

2. Description of the Related Art Conventionally, there is known an oil supply device for an internal combustion engine that discharges oil stored in an oil pan from an oil pump and supplies the oil to a lubrication site.
Usually, the lubrication part is a lubrication part of an internal combustion engine such as a hydraulic variable mechanism or a hydraulic lash adjuster of a valve system, such as a hydraulic operation mechanism mounted on an internal combustion engine, or a rotational sliding part of a crankshaft or a camshaft. And so on.

  The oil discharged from the oil pump is supplied to the plurality of lubrication sites through an oil supply path in the order of, for example, a hydraulic variable valve mechanism, a hydraulic lash adjuster, and a lubrication site of the internal combustion engine.

  Conventionally, in an internal combustion engine mounted on a vehicle, an oil discharge pressure proportional to the rotational speed of the internal combustion engine is set as an oil supply device that supplies oil used for lubrication and cooling of the internal combustion engine to a lubrication part of the internal combustion engine. An oil pump is used.

By the way, the oil stored in the oil pan is supplied to the lubrication site by the oil pump, and is collected in the oil pan after the lubrication site is lubricated and cooled.
At this time, if the amount of oil stored in the oil pan is small, the recovery efficiency of the oil recovered in the oil pan deteriorates, and the oil level (oil level) stored in the oil pan is less than the appropriate amount. Decline, that is, lack.

  When the oil level decreases in this way, the strainer for sucking oil from the oil pan toward the oil pump may be in a state of sucking air (hereinafter, this state is referred to as air sucking).

When the oil pump is in the air sucking state, the oil discharge pressure discharged from the oil pump is reduced, so that a sufficient amount of oil cannot be supplied from the oil pump to the lubrication site, and the lubricity of the lubrication site is reduced. There is a risk of getting worse.
For this reason, it is necessary to warn the driver that the oil level stored in the oil pan has decreased and to prompt the driver to replenish the oil.

  As a conventional oil level detection device, one having an oil level sensor that detects an oil level stored in an oil pan is known (see, for example, Patent Document 1). The oil level sensor is composed of a float and a link mechanism provided in the oil pan, and detects that the oil level is lowered by detecting that the float moves together with the oil as the oil level is lowered. It has become.

Further, as a conventional oil level detection device, one having an oil level gauge for checking the oil level in the oil pan is known (for example, see Patent Document 2).
The oil level gauge is attached to the internal combustion engine in a state where the oil level gauge is inserted into a through hole formed in the internal combustion engine. When the oil level gauge is attached to the internal combustion engine, its tip is immersed in the oil filled in the oil pan. It has become.

  This oil level detection device can confirm the oil level and state in the oil pan by removing the oil level gauge attached to the internal combustion engine and visually observing the oil adhering to the tip of the oil level gauge.

JP 2008-286063 A JP 2009-180166 A

  However, such a conventional oil level sensor is provided with a float, a link mechanism, and the like and is very expensive. Therefore, when the oil level sensor is configured to detect the oil level in the oil pan, The manufacturing cost of the oil level detector increases.

  In addition, the conventional oil level gauge relies on the driver for the oil check operation, so that a driver who does not frequently check the oil may not notice that the oil level has decreased.

  The present invention has been made to solve the above-described conventional problems, and an oil level detection device that can reliably detect, with an inexpensive configuration, that the oil level stored in the oil storage means has decreased. The purpose is to provide.

  In order to achieve the above object, an oil level detection device according to the present invention is (1) an oil level detection device for detecting an oil level stored in an oil storage means of an internal combustion engine, wherein the crankshaft of the internal combustion engine is The amount of oil mist in the crank chamber is detected based on the high frequency component of the pressure detection value in the stored crank chamber, and the oil level is set on condition that the pressure value of the high frequency component is not more than a predetermined threshold value. It is comprised from what was provided with the oil level detection means which detects that it fell.

  This oil level detection device detects the amount of oil mist in the crank chamber based on the high frequency component of the pressure detection value in the crank chamber of the internal combustion engine.

  The pressure fluctuation in the crank chamber is a frequency component including a low frequency component of the pressure fluctuation in the crank chamber caused by rotation of the crankshaft of the internal combustion engine (reciprocating motion of the piston) and a high frequency component mainly due to scattering of oil mist. ing.

  As the amount of oil mist in the crank chamber increases, the amplitude of the high-frequency component of the pressure fluctuation in the crank chamber increases. Therefore, the amount of oil mist in the crank chamber can be detected based on the high-frequency component in the crank chamber.

  Also, the oil mist in the crank chamber is, for example, scraped up from the oil pan by the air flow caused by the rotation of the counterweight provided on the crankshaft, or the oil dropped by the engine block after lubricating the lubricated part of the internal combustion engine is cranked. It occurs when it collides with the shaft and scatters.

  For this reason, if the amount of oil stored in the oil storage means is large, the amount of oil mist in the crank chamber increases, and the amplitude of the high-frequency component of the pressure fluctuation in the crank chamber increases. Further, when the amount of oil stored in the oil storage means is small, the amount of oil mist in the crank chamber is reduced, and the amplitude of the high frequency component of the pressure fluctuation in the crank chamber is reduced.

  Therefore, on the condition that the pressure value of the high frequency component of the pressure fluctuation in the crank chamber is equal to or less than a predetermined threshold, it is possible to eliminate the need for an expensive oil level sensor by detecting that the oil level has decreased. It is unnecessary to depend on the driver for the oil check work, and the oil level detection device can reliably detect that the oil level has been lowered with an inexpensive configuration.

  (1) In the oil level detection device according to (1), (2) a pressure sensor that detects a pressure in the crank chamber is provided, and the oil level detection unit is configured to perform the operation based on a high-frequency component of a pressure detection value acquired from the pressure sensor. It consists of what detects the amount of oil mist in the crank chamber.

  This oil level detection device detects the amount of oil mist in the crank chamber based on the high frequency component of the pressure detection value acquired from the pressure sensor by the oil level detection means, so that the pressure fluctuation in the crank chamber can be determined from the measured value of the crank chamber pressure. Can be reliably detected.

  In the oil level detection device of (1) or (2), (3) warning means for warning that the oil level has decreased based on a drive signal input from the oil level detection means, and the oil level detection means Is configured to output the drive signal to the warning means on condition that the pressure value of the high-frequency component is not more than a predetermined threshold value.

  In this oil level detection device, the oil level detection means warns by the warning means on the condition that the pressure value of the high frequency component is equal to or less than a predetermined threshold value. Can be warned. For this reason, the driver can be urged to replenish the oil storage means with oil, the oil level in the oil storage means is made appropriate, and the lubricity of the lubrication part of the internal combustion engine is deteriorated. Can be prevented.

  In the oil level detection device according to the above (1) to (3), (4) the oil level detection means has a frequency equal to or higher than a frequency corresponding to a maximum rotational speed of the internal combustion engine from a frequency component of a pressure detection value in the crank chamber. The high frequency component is extracted, and the oil mist amount is detected from the extracted high frequency component.

  In this oil level detection device, the oil level detection means extracts a high frequency component equal to or higher than the frequency corresponding to the maximum rotational speed of the internal combustion engine from the frequency component of the pressure detection value in the crank chamber, and the amount of oil mist from the extracted high frequency component Therefore, the low frequency component of the crank chamber pressure fluctuation caused by the rotation of the crankshaft of the internal combustion engine can be removed from the frequency component of the crank chamber pressure fluctuation, and only the high frequency component can be detected.

  For this reason, the oil level detection means can accurately detect the amount of oil mist in the crank chamber, and can accurately detect that the oil level in the oil storage means has decreased based on the amount of oil mist. it can.

  In the oil level detection device according to the above (1) to (4), (5) having a rotation speed detection means for detecting the rotation speed of the internal combustion engine, the oil level detection means depending on the rotation speed of the internal combustion engine. The oil is changed on the condition that the threshold value is changed and the pressure value of the high-frequency component is not more than a threshold value set according to the rotation speed of the internal combustion engine based on detection information of the rotation speed detection means. It is comprised from what was provided with the oil level detection means which detects that the level fell.

The amount of oil mist scattered in the crank chamber increases as the rotational speed of the internal combustion engine increases, and is proportional to the rotational speed of the internal combustion engine. For this reason, the high frequency component of the pressure value in the crank chamber increases as the rotational speed of the internal combustion engine increases.
For this reason, if the threshold value of the pressure value of the high frequency component is made constant regardless of the rotational speed of the internal combustion engine, the oil level cannot be determined accurately.

  Therefore, the oil level detection means sets the optimum threshold value according to the high-frequency component in the crank chamber that varies according to the rotational speed of the internal combustion engine by changing and setting the threshold value according to the rotational speed of the internal combustion engine. Based on the rotational speed of the internal combustion engine detected by the rotational speed detection means, the oil level has decreased on condition that the pressure value of the high frequency component is not more than a threshold value set according to the rotational speed of the internal combustion engine. Detect.

  In this way, it is possible to detect with high accuracy that the oil level of the oil storage means has decreased.

  ADVANTAGE OF THE INVENTION According to this invention, the oil level detection apparatus which can detect reliably that the oil level stored in an oil storage means fell with the cheap structure can be provided.

1 is a diagram illustrating an embodiment of an oil level detection device according to the present invention, and is a schematic configuration diagram of an internal combustion engine including the oil level detection device. It is a figure which shows one Embodiment of the oil level detection apparatus which concerns on this invention, and is a figure which shows the relationship between an engine speed and the amount of oil splashes in a crank chamber. It is a figure which shows one Embodiment of the oil level detection apparatus which concerns on this invention, and is a figure which shows the relationship between the pressure value of the high frequency component in a crank chamber, and the amount of oil splashes. It is a figure which shows one Embodiment of the oil level detection apparatus which concerns on this invention, and is the elements on larger scale of FIG. It is a figure which shows one Embodiment of the oil level detection apparatus which concerns on this invention, and is a figure which shows the waveform of the pressure of a crank chamber when the amount of oil mist in a crank chamber is large. It is a figure which shows one Embodiment of the oil level detection apparatus which concerns on this invention, and is a figure which shows the waveform of the pressure of a crank chamber when the amount of oil mists in a crank chamber is small. It is a figure which shows one Embodiment of the oil level detection apparatus which concerns on this invention, and is a figure which shows the waveform of the pressure of the crank chamber after the signal processing by HPF of a signal processing circuit. It is a figure which shows one Embodiment of the oil level detection apparatus which concerns on this invention, and is a figure which shows the waveform of the pressure of the crank chamber after the signal processing by the half wave rectifier circuit of a signal processing circuit. It is a figure which shows one Embodiment of the oil level detection apparatus which concerns on this invention, and is a figure which shows the waveform of the pressure of the crank chamber after the signal processing by LPF of a signal processing circuit. It is a figure which shows one Embodiment of the oil level detection apparatus which concerns on this invention, and is a figure which shows the flowchart of an oil level detection process program.

Embodiments of an oil level detection device according to the present invention will be described below with reference to the drawings.
1-10 is a figure which shows one Embodiment of the oil level detection apparatus based on this invention.

First, the configuration will be described.
In FIG. 1, an engine 1 as an internal combustion engine includes an engine body 10 and an oil level detection device 30.

The engine body 10 includes a cylinder block 11, a cylinder head (not shown) provided in the cylinder block 11, and an oil pan 12 provided in the lower part of the cylinder block 11.
A piston 13 is provided in the cylinder block 11 so as to be movable up and down, and the piston 13 is connected to a crankshaft 15 via a connecting rod 14.

The crankshaft 15 is housed in a crank chamber 16 formed in the lower part of the cylinder block 11 and is rotatably provided in the cylinder block 11 via a bearing cap 16 a provided in the crank chamber 16.
Note that the crank chamber 16 of the present embodiment is formed by the cylinder block 11. Further, a crankcase may be fixed to the lower part of the cylinder block, and a crank chamber may be formed by the inside of the crankcase.

  The crankshaft 15 balances the overall weight balance between the crankpin 17 to which the piston 13 is attached via the connecting rod 14, the crank journal 18 rotatably supported by the bearing cap 16 a in the crank chamber 16, and the crankshaft 15. And a counterweight 19 for taking. The counter weight 19 is provided in a number corresponding to the number of cylinders of the engine 1.

  In the engine 1, when the piston 13 reciprocates up and down by combustion energy when fuel burns in the combustion chamber during operation of the engine 1, the reciprocating motion is converted into the rotational motion of the crankshaft 15 via the connecting rod 14. It is converted and output.

The oil pan 12 constitutes an oil storage means, and engine oil (hereinafter simply referred to as oil) is stored in the oil pan 12. In FIG. 1, the height of the oil level H1 corresponds to the oil level.
An oil strainer (not shown) is provided in the oil pan 12, and the oil strainer is disposed so that the lower end portion is always immersed in the oil in the oil pan 12.

  Further, the upper end of the oil strainer is connected to an oil pump (not shown), and when the engine 1 is operated, the oil pump is operated to suck in and pump up oil stored in the oil pan 12.

  The oil used for lubrication and cooling of each part in the engine body 10 is collected in the oil pan 12 by dropping or flowing down in the engine body 10. A baffle plate 20 is provided between the crankshaft 15 and the oil pan 12, and the baffle plate 20 is disposed at a position where it does not interfere with the crankshaft 15.

  In addition, a pressure sensor 21 as a pressure detection unit is provided inside the cylinder block 11, and the pressure sensor 21 is installed at a position facing one counterweight 19.

  The pressure sensor 21 includes a pressure introduction pipe 22 and a pressure detection unit 23. The base end portion 22 a of the pressure introduction pipe 22 is connected to the pressure detection unit 23, and the pressure in the crank chamber 16 is transmitted to the pressure detection unit 23 via the pressure introduction pipe 22. The pressure detector 23 is configured such that the output signal increases as the pressure in the crank chamber 16 increases.

  Note that the shape of the oil pan 12 is not uniform, and has a step or the like depending on the location, and there is a portion of oil stored in the oil pan 12 at a position higher than the bottom surface of the oil pan 12. Will do.

  For this reason, the height of the oil in the oil pan 12 differs depending on the location of the oil pan 12. Therefore, it is preferable that the pressure sensor 21 be installed to face the counterweight 19 located above the place where the oil level in the oil pan 12 is highest.

  This is because when the oil level is lowered, the oil stored on the step higher than the bottom surface of the oil pan 12 flows into the oil located on the bottom surface of the oil pan from above the step, and the oil is scraped by the rotating air current of the counterweight. This is because the pressure sensor 21 may not be able to detect the pressure of the oil mist with high accuracy.

  Further, the crankshaft 15 is provided with a rotational speed sensor 24 as a rotational speed detecting means. The rotational speed sensor 24 detects the engine rotational speed from the rotation of the crankshaft 15 in a predetermined angle unit and generates an electric signal. It is converted and output.

  The oil level detection device 30 includes an oil level detection unit 31, and the oil level detection unit 31 includes a signal processing circuit 32 and an electronic control unit (hereinafter referred to as an ECU) 33. Yes.

  The signal processing circuit 32 includes an HPF (High Pass Filter) 34, a half-wave rectifier circuit 35, and an LPF (Low Pass Filter) 36.

  The HPF 34 removes a low frequency component from the frequency component of the pressure detection value in the crank chamber 16 input from the pressure sensor 21.

  This low frequency component is a frequency component corresponding to the maximum rotational speed of the engine 1, and the HPF 34 extracts a high frequency component equal to or higher than this low frequency component.

  The half-wave rectifier circuit 35 performs processing for removing the negative component of the signal input from the HPF 34. That is, the half-wave rectifier circuit 35 extracts only the positive component of the signal input from the HPF 34. The LPF 36 performs a process of smoothing the signal input from the half-wave rectifier circuit 35.

  As described above, the signal processing circuit 32 executes processing for detecting the amount of oil mist in the crank chamber 16 based on the high frequency component of the pressure detection value in the crank chamber 16 detected by the pressure sensor 21.

The ECU 33 is composed of, for example, an electronic circuit mainly composed of a microcomputer, and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like.
The ROM stores an oil level detection program, an oil level determination map that is referred to when the oil level detection program is executed, and the like.

The oil level determination map stores an engine speed and a threshold value for determining an oil level corresponding to the engine speed in association with each other.
The RAM is a memory that temporarily stores calculation results of the CPU, data input from each sensor, and the like.

  The ECU 33 refers to the oil level determination map on the basis of the signal input from the signal processing circuit 32 and the signal input from the rotation speed sensor 24, and the pressure value of the high frequency component input from the signal processing circuit 32 is the engine rotation speed. A process of detecting that the oil level has decreased is executed on condition that the oil level is equal to or less than a threshold value determined according to the number.

  The ECU 33 is electrically connected with a warning lamp 37 as a warning means provided on the meter panel. When the drive signal is input from the ECU 33, the warning lamp 37 is lit or blinked to warn the driver, an operator when performing maintenance, or the like that the oil level in the oil pan 12 has decreased.

  Further, the warning means is not limited to the warning lamp 37, and may be constituted by a buzzer or a speaker that generates an alarm sound or a sound.

Next, a method for measuring the oil mist in the crank chamber 16 by the signal processing circuit 32 will be described.
The amount of oil mist present in the crank chamber 16 varies depending on the operating state of the engine. As shown in FIG. 2, when the oil level in the oil pan 12 is greater by Amm than the appropriate level, the amount of oil splash increases as indicated by A.

  Further, when the oil level in the oil pan 12 is Bmm less than the appropriate level, as shown by B, the amount of oil splash is reduced. Thus, the oil splash amount has a characteristic that increases as the engine speed increases.

As shown in FIG. 3, when the amount of oil splash in the crank chamber 16 is increased at the same engine speed, the higher the high frequency component of the pressure in the crank chamber 16, the greater the amount of oil splash. , Get higher.
Therefore, as apparent from FIGS. 2 and 3, the smaller the pressure fluctuation width of the high-frequency component in the crank chamber 16, the smaller the amount of oil splashed in the crank chamber 16, and the smaller the amount of oil splashed. This can be said that the oil level of the oil pan 12 is lowered.

  As shown in FIG. 4, when the oil mist passes near the tip 22 a of the pressure introduction pipe 22 of the pressure sensor 21, when the oil mist O1 approaches the tip 22 a of the pressure introduction pipe 22, the pressure sensor 21. The pressure in the crank chamber 16 detected by this increases.

  Conversely, when the oil mist O2 moves away from the tip end portion 22a of the pressure introducing pipe 22, the pressure in the crank chamber 16 detected by the pressure sensor 21 decreases.

  However, since the direction in which the oil mist flies is random, the overall pressure fluctuation in the crank chamber 16 shows the behavior shown in FIG. 5 when the amount of oil mist in the crank chamber 16 is large. When the amount of oil mist in 16 is small, the behavior shown in FIG. 6 is shown.

  FIG. 7 shows a waveform after the signal processing by the HPF 34 is performed on the detection signal of the pressure sensor 21. The HPF 34 extracts a component having a fast pressure fluctuation in the crank chamber 16.

  In the signal processing by the HPF 34, a signal with a large fluctuation width is obtained as the pressure fluctuation in the crank chamber 16 is faster, that is, as the pressure fluctuation frequency is higher. For this reason, as the amount of oil mist in the crank chamber 16 increases, a signal with a large swing width is obtained.

  The value of the frequency extracted by the HPF 34 can be arbitrarily set as long as it is a value sufficiently higher than the maximum rotation speed of the engine body 10, and is set to 1 kHz, for example.

  If the maximum rotational speed of the engine body 10 is, for example, 6000 rpm, 6000 rpm corresponds to 100 Hz, so 1 kHz is a value sufficiently higher than the rotational speed of the engine body 10. For this reason, the pressure fluctuation in the crank chamber 16 due to the rotation of the crankshaft 15 of the engine body 10 (reciprocating motion of the piston 13) is removed by the HPF 34. In this case, the high-frequency component extracted by the HPF 34 is mainly a component of pressure fluctuation due to fluctuation of the oil mist amount in the crank chamber 16.

  Next, as shown in FIG. 8, the negative frequency component of the signal output from the HPF 34 is cut by the half-wave rectifier circuit 35, and the positive frequency component is extracted. FIG. 8 shows the waveform of the pressure in the crank chamber 16 after the signal processing by the half-wave rectifier circuit 35 is performed on the signal after the signal processing by the HPF 34 shown in FIG.

  The half-wave rectifier circuit 35 provides a pulse-like signal with negative frequency components cut off. Here, a signal component larger than the reference pressure value P1 (for example, average pressure) in FIG. 7 is a positive component, and a frequency component of a signal smaller than the reference pressure value P1 is a negative frequency component. In the signal processing by the half-wave rectifier circuit 35, a larger value (wave height) pulse is obtained as the amount of oil mist in the crank chamber 16 increases.

  Next, as shown in FIG. 9, the LPF 36 averages the pulse-like signal output from the half-wave rectifier circuit 35 to obtain a smooth signal. In FIG. 9, the waveform of the pressure in the crank chamber 16 after the signal processing by the LPF 36 is performed on the signal shown in FIG. 5 after the signal processing by the half-wave rectifier circuit 35 is indicated by a solid line.

  Moreover, the solid line shows the waveform of the pressure in the crank chamber 16 after the signal processing by the LPF 36 is performed on the signal shown in FIG. 6 after the signal processing by the half-wave rectifier circuit 35. In the signal processing by the LPF 36, a larger value signal is obtained as the input pulse is larger. For this reason, the larger the amount of oil mist in the crank chamber 16 is, the larger the value of the signal is obtained. The smaller the amount of oil mist in the crank chamber 16 is, the smaller the value of the signal shown in FIG. It will be.

  Next, the oil level detection process will be described based on the flowchart shown in FIG. The flowchart shown in FIG. 10 is an oil level detection program executed by the ECU 33.

  First, the ECU 33 reads the rotation speed of the crankshaft 15, that is, the engine rotation speed, based on the detection information from the rotation speed sensor 24 (step S1).

  Next, the ECU 33 refers to the oil level determination map stored in the ROM, and obtains a threshold value P corresponding to the rotational speed detected by the rotational speed sensor 24 (step S2).

  The threshold P is assigned to a high-frequency component (oil mist amount) corresponding to the engine speed. For example, in the range of 1500 rpm to 1600 rpm, AkPa, and in the range of 1600 rpm to 1700 rpm, BkPa. The engine speed is assigned with a width.

  The threshold value P is set lower than the pressure value of the high frequency component when the oil level is appropriate. For this reason, it is possible to prevent the warning from being performed in a state where the oil level is slightly lower than the appropriate level.

  Next, the ECU 33 acquires the pressure value Pi of the high frequency component detected by the signal processing circuit 32 (step S3), and determines whether or not the acquired pressure value Pi is equal to or less than the threshold value P (step S4). .

  As shown in FIG. 9, when the ECU 33 determines that the pressure value Pi exceeds the threshold value P, for example, the ECU 33 determines that the oil level in the oil pan 12 has not decreased to a level at which replenishment is performed. Then, the process returns to step S1.

  Further, as shown in FIG. 9, when the ECU 33 determines that the pressure value Pi is equal to or less than the threshold value P, for example, the oil level in the oil pan 12 is lowered to a level at which oil is replenished. It determines with a thing, a drive signal is output to the warning lamp 37 (step S5), and this process is complete | finished.

  When a driving signal is input from the ECU 33, the warning lamp 37 warns that the oil level in the oil pan 12 is lowered to a driver or an operator who performs maintenance by lighting or blinking.

  For this reason, the driver determines that the oil in the oil pan 12 is insufficient, and performs an operation of replenishing the oil pan 12 with oil.

  Thus, in the oil level detection device 30 of the present embodiment, the signal processing circuit 32 detects the amount of oil mist in the crank chamber 16 based on the high frequency component of the pressure detection value in the crank chamber 16 of the engine 1, The ECU 33 is configured to detect that the oil level has decreased on the condition that the pressure value of the high-frequency component of the pressure fluctuation in the crank chamber 16 is equal to or less than a predetermined threshold value.

  For this reason, the oil level detection device 30 can eliminate the need for an expensive oil level sensor, and can also eliminate the need to depend on the driver for the oil check work. The oil level detection device 30 has an inexpensive configuration and the oil level is low. It is possible to reliably detect the decrease.

  The oil level detection device 30 of the present embodiment includes a pressure sensor 21 that detects the pressure in the crank chamber 16, and the signal processing circuit 32 is based on the high-frequency component of the pressure detection value acquired from the pressure sensor 21. Since the amount of oil mist in the crank chamber 16 is detected, the pressure fluctuation in the crank chamber 16 can be reliably detected from the actually measured value in the crank chamber 16.

  In addition, the oil level detection device 30 of the present embodiment performs a warning by the warning lamp 37 on the condition that the pressure value of the high-frequency component is equal to or less than a predetermined threshold value, so that the oil level has decreased. The driver can be warned. For this reason, the driver can be urged to replenish oil in the oil pan 12, the oil level of the oil pan 12 is made appropriate, and the lubricity of the lubrication part of the engine 1 is deteriorated. Can be prevented.

  Further, in the oil level detection device 30 of the present embodiment, the signal processing circuit 32 extracts a high frequency component equal to or higher than the frequency corresponding to the maximum rotational speed of the engine 1 from the frequency component of the pressure detection value in the crank chamber 16, Since the oil mist amount is detected from the extracted high frequency component, the low frequency component of the pressure fluctuation in the crank chamber 16 caused by the rotation of the crankshaft 15 of the engine 1 is removed from the frequency component of the pressure fluctuation in the crank chamber 16 to obtain a high frequency. Only ingredients can be obtained.

For this reason, the signal processing circuit 32 can accurately detect the amount of oil mist, and the ECU 33 can accurately detect that the oil level in the oil pan 12 has decreased based on the amount of oil mist. .
Further, in the oil level detection device 30 of the present embodiment, the ECU 33 changes and sets the threshold according to the rotational speed of the engine 1.

  That is, as shown in FIG. 2, the amount of oil mist scattered in the crank chamber 16 increases as the rotational speed of the engine 1 increases, and is proportional to the rotational speed of the engine 1. For this reason, the high frequency component in the crank chamber 16 increases as the rotational speed of the engine 1 increases.

  For this reason, if the threshold value of the pressure value of the high frequency component is made constant regardless of the rotational speed of the engine 1, the oil level cannot be accurately determined.

  Therefore, the ECU 33 according to the present embodiment sets an optimum threshold value according to the high-frequency component in the crank chamber 16 that varies according to the engine speed by changing and setting the threshold value according to the engine speed. Based on the engine rotational speed detected by the rotational speed sensor 24, it is detected that the oil level has fallen on condition that the pressure value of the high frequency component is not more than a threshold value set according to the engine rotational speed. ing.

In this way, it is possible to detect with high accuracy that the oil level in the oil pan 12 has decreased.
In this embodiment, the pressure sensor 21 is provided at a position facing one counterweight 19, but a pressure sensor may be provided at a position facing each of the two or more counterweights 19.

  Further, in the present embodiment, an example in which the oil level detection device is applied to a vehicle internal combustion engine has been described. However, the oil level detection device can be applied as long as it uses an internal combustion engine as a power source. The present invention is applicable not only to internal combustion engines mounted on so-called hybrid vehicles and motorcycles, but also to internal combustion engines mounted on other than vehicles such as ships and construction equipment.

  As described above, the oil level detection device according to the present invention has an effect of reliably detecting, with an inexpensive configuration, that the oil level stored in the oil storage means has decreased. This is useful as an oil level detection device for detecting the oil level stored in the storage means.

1 engine (internal combustion engine)
12 Oil pan (oil storage means)
15 Crankshaft 21 Pressure sensor (pressure detection means)
24 Rotational speed sensor (Rotational speed detection means)
30 Oil level detection device 31 Oil level detection means 37 Warning lamp (warning means)

Claims (5)

An oil level detection device for detecting an oil level stored in an oil storage means of an internal combustion engine,
The amount of oil mist in the crank chamber is detected based on the high frequency component of the pressure detection value in the crank chamber in which the crankshaft of the internal combustion engine is housed, and the pressure value of the high frequency component is below a predetermined threshold value. An oil level detection device for an internal combustion engine, characterized by comprising oil level detection means for detecting that the oil level has fallen as a condition.   A pressure sensor for detecting the pressure in the crank chamber is provided, and the oil level detection means detects the amount of oil mist in the crank chamber based on a high frequency component of a pressure detection value acquired from the pressure sensor. The oil level detection device for an internal combustion engine according to claim 1. Warning means for warning that the oil level has dropped based on the drive signal input from the oil level detection means;
3. The oil level detection means outputs the drive signal to the warning means on condition that the pressure value of the high frequency component is not more than a predetermined threshold value. An oil level detection device for an internal combustion engine as described.   The oil level detection means extracts a high frequency component equal to or higher than a frequency corresponding to the maximum rotational speed of the internal combustion engine from a frequency component of a pressure detection value in the crank chamber, and detects an oil mist amount from the extracted high frequency component. The oil level detection device for an internal combustion engine according to any one of claims 1 to 3, wherein the oil level detection device is an internal combustion engine. Having a rotational speed detection means for detecting the rotational speed of the internal combustion engine;
The oil level detection means changes and sets the threshold according to the rotational speed of the internal combustion engine, and the pressure value of the high-frequency component becomes the rotational speed of the internal combustion engine based on detection information of the rotational speed detection means. The oil level detection means which detects that the said oil level fell on condition that it is below the threshold value set according to it according to any one of Claim 1 thru | or 4 characterized by the above-mentioned. Oil level detection device.