JP5743279B2 - Engine oil level detector - Google Patents

Description

  The present invention relates to an engine lubricating oil amount detection device for detecting the amount of lubricating oil stored in an engine oil pan.

  There is a specified amount of lubricant stored in the oil pan of the engine. To prevent engine seizure and oil from rising and drive the engine well, keep the lubricant within the specified amount. There is a need. For this reason, a device has been developed that automatically detects the amount of lubricating oil and issues a warning to the driver when an abnormality in the amount of oil occurs.

  Such devices generally detect oil level abnormalities by detecting the oil level (oil level) of the lubricating oil in the oil pan. The oil level changes in response to For this reason, Patent Document 1 discloses a technique for correcting the detected value of the oil level of the lubricating oil based on the temperature of the lubricating oil, and calculating the consumption amount of the lubricating oil based on the value of the corrected oil level. Is disclosed.

Japanese Patent No. 3205173

  However, the oil level of the lubricating oil varies not only with the temperature of the lubricating oil (oil temperature) but also with the engine speed. Under conditions where the oil temperature and the engine speed are constant, the oil level and the amount of oil are approximately proportional to each other. Therefore, as shown in FIG. 7, the oil level is maintained under the condition where the oil temperature and the engine speed are constant. By detecting this, it is possible to detect the same oil level with the same oil amount without being affected by the oil temperature and the engine speed.

  In this case, there are fewer opportunities to satisfy the conditions under constant oil temperature and engine speed, and the detection frequency is greatly reduced. Therefore, in order to ensure a certain level of detection frequency, it is necessary to provide a range for both conditions of the oil temperature and the engine speed, but if the oil temperature or the engine speed changes, the oil level Even if the detected value is the same, there is a range in the amount of oil obtained.

  FIG. 8 shows the relationship between the oil level and the oil amount when the oil temperature changes from high to low under a condition where the engine speed is constant. When the oil temperature changes from low to high, Even if the oil level is the same, the oil amount in the oil amount range At is obtained, and the oil level is higher when the oil temperature is higher than when the oil temperature is low even if the oil amount is the same. This is because the higher the oil temperature, the faster the return to the oil pan occurs due to the volume expansion and viscosity reduction of the lubricating oil.

  FIG. 9 shows the relationship between the oil level and the amount of oil when the engine speed changes from high to low under a constant oil temperature. The engine speed changes from low to high. In this case, the oil amount in the oil amount width An is obtained even at the same oil level, and the oil level is lower when the engine speed is higher than when the engine speed is low even with the same oil amount. This is because the amount of oil taken out from the oil pan is higher when the engine speed is higher.

  Furthermore, under conditions where the engine speed and the oil temperature change independently, the number of detection opportunities is the largest, but the oil amount width is widest for the same oil level. Conversely, it changes to various oil level levels with the same amount of oil.

  Thus, when detecting the oil amount from the detected value of the oil level, the frequency of detection can be secured by giving a certain range to both conditions of the engine speed and the oil temperature. On the other hand, when the detection frequency is increased, the width of the oil amount detected from the same oil level is increased, and the detection accuracy is lowered.

  The present invention has been made in view of the above circumstances, and provides an engine lubricating oil amount detection device capable of ensuring both the detection frequency and the detection accuracy while suppressing the influence of the engine speed and the temperature of the lubricating oil. The purpose is to do.

  According to the present invention, there is provided an engine lubricating oil amount detecting device for detecting an oil amount of the lubricating oil based on an oil level of lubricating oil stored in an engine oil pan. An oil level sensor for detecting the oil level of the lubricating oil in the pan, and whether or not the engine speed and the temperature of the lubricating oil are within a set region set in correlation with each other, An oil amount detection process execution determination unit that determines whether or not to perform an oil amount detection process based on an output value of the oil level sensor.

  According to the present invention, both the detection frequency and the detection accuracy can be ensured while suppressing the influence of the engine speed and the temperature of the lubricating oil.

Schematic showing the lubricant level detector Schematic showing the oil level sensor Functional block diagram for detecting the amount of lubricant Explanatory drawing which shows the change of the oil quantity width by the correlation setting of engine speed and oil temperature Illustration of diagnosis area Flow chart of oil amount abnormality diagnosis processing Explanatory drawing showing the relationship between the oil level and oil quantity at a constant oil temperature and engine speed Explanatory drawing showing the relationship between the oil level and the oil amount when the engine speed is constant Explanatory diagram showing the relationship between the oil level and oil amount when the oil temperature is constant

Embodiments of the present invention will be described below with reference to the drawings.
In FIG. 1, reference numeral 10 denotes a lubricating oil amount detection device that detects the amount of lubricating oil stored in an oil pan 12 attached to the lower part of the engine 11. Lubricating oil stored in the oil pan 12 is circulated in the engine 11, and each sliding portion in the engine 11 is lubricated to maintain a good driving state of the engine 11.

  In order to circulate the lubricating oil in the engine 11, an oil passage is formed in the cylinder block 13 and the cylinder head 14, and an oil strainer 15, an oil pump (not shown), an oil filter, an oil cooler, and the like are assembled in the engine 11. ing. The lubricating oil sucked from the oil strainer 15 by driving the oil pump is guided to the oil cooler and the oil filter via the oil pump, and then introduced into the oil passages of the cylinder block 13 and the cylinder head 14. Then, the lubricating oil that has lubricated the crank mechanism and the valve mechanism is returned to the oil pan 12 again.

  An oil level sensor 16 for detecting the oil level of the lubricating oil is installed in the oil pan 12 in which the lubricating oil is stored. Based on the output value of the oil level sensor 16, the oil of the lubricating oil An oil amount detection process for detecting the amount is carried out by an electronic control unit (ECU) 50 configured mainly with a microcomputer. In the present embodiment, the oil amount detection process in the ECU 50 is performed as a process of diagnosing an abnormality in the oil level, that is, an abnormality in the oil amount of the lubricating oil, from the output value of the oil level sensor 16 (the detected value of the oil level). When the lubricating oil amount is out of the appropriate amount range, the oil amount warning lamp 30 is turned on to issue a warning to the driver. The ECU 50 is connected to the power source 2 via an ignition switch 1 that is turned on and off by a driver's operation.

  As will be described later, when the abnormality of the oil level is diagnosed, the ECU 50 performs a diagnosis process in an area set by correlating the engine speed and the temperature of the lubricating oil (oil temperature), and provides an opportunity for diagnosis. While ensuring, it suppresses the influence by an engine speed and oil temperature, and aims at the improvement of detection accuracy. Therefore, the ECU 50 receives a signal from the crank angle sensor 17 provided on the outer periphery of the crank rotor 11b that is attached to the crankshaft 11a of the engine 11 and a signal from the oil temperature sensor 18 that faces the oil pan 12. When the region based on the engine speed based on the signal from the crank angle sensor 17 and the oil temperature based on the signal from the oil temperature sensor 18 is within the set region, an abnormality diagnosis of the oil level is performed.

  Here, the configuration of the oil level sensor 16 will be described. In the present embodiment, the oil level sensor 16 is configured by a float switch, and is configured to be able to detect an upper limit level Lh and a lower limit level Ll that define an appropriate amount range of the lubricating oil. Specifically, as shown in FIG. 2, the oil level sensor 16 includes a hollow support shaft 20, and an annular upper limit float 24 and a lower limit float 25 including magnets are movable up and down on the support shaft 20. It is supported.

  End stoppers 21 and 22 are assembled at both ends of the support shaft 20, and an intermediate stopper 23 is assembled at substantially the center in the longitudinal direction of the support shaft 20. The upper limit float 24 is disposed between the end stopper 21 and the intermediate stopper 23, and the lower limit float 25 is disposed between the end stopper 22 and the intermediate stopper 23.

  The upper limit float 24 and the lower limit float 25 are formed of a material having a lighter specific gravity than the lubricating oil, and the upper limit float 24 is partitioned by the end stopper 21 and the intermediate stopper 23 according to the oil level of the lubricating oil. The lower limit float 25 moves up and down within the first detection range R1, and the lower limit float 25 moves up and down within the second detection range R2 defined by the end stopper 22 and the intermediate stopper 23.

  The support shaft 20 accommodates an upper limit reed switch 26 that is an upper limit switch and a lower limit reed switch 27 that is a lower limit switch. The upper limit reed switch 26 is disposed between the end stopper 21 and the intermediate stopper 23, and the lower limit reed switch 27 is disposed between the end stopper 22 and the intermediate stopper 23.

  The upper limit reed switch 26 is connected to the power source 2 via the ECU 50, the lower limit reed switch 27 is grounded, and the upper limit reed switch 26 and the lower limit reed switch 27 are connected in series. As described above, the abnormality detection circuit 28 that detects the oil amount abnormality of the lubricating oil is formed by the power source 2, the ECU 50, the upper limit reed switch 26, and the lower limit reed switch 27 that are connected to each other.

  The upper limit reed switch 26 substantially faces the magnet 24a of the upper limit float 24 when the upper limit float 24 moves to the lower end of the detection range R1, that is, when it contacts the intermediate stopper 23 that sets the lower end of the detection range R1. Are arranged as follows. The lower limit reed switch 27 substantially faces the magnet 25a of the lower limit float 25 when the lower limit float 25 moves to the upper end of the detection range R2, that is, when it contacts the intermediate stopper 23 that sets the upper end of the detection range R2. Are arranged as follows.

  Such reed switches 26 and 27 operate as follows. When the magnets 24a and 25a incorporated in the floats 24 and 25 approach the reed switches 26 and 27, sufficient magnetic field lines pass through the metal plates of the reed switches 26 and 27, and the reed is generated by the attractive force acting on the metal plates. While the contacts of the switches 26 and 27 are closed, when the magnets 24a and 25a incorporated in the floats 24 and 25 are separated from the reed switches 26 and 27, the magnetic lines of force that have passed through the metal plate are reduced. The contacts of the reed switches 26 and 27 are opened by the spring force of.

  Therefore, as indicated by a solid line in FIG. 2, when the lubricating oil drops to the lower limit level L1, the magnet 25a of the lower limit float 25 is separated from the lower limit reed switch 27, so that the contact of the lower limit reed switch 27 is opened. Further, as indicated by a broken line in FIG. 2, when the lubricating oil rises to the upper limit level Lh, the magnet 24a of the upper limit float 24 is separated from the upper limit reed switch 26, so that the contact of the upper limit reed switch 26 is opened. When the oil level is within an appropriate range, that is, between the upper limit level Lh and the lower limit level L1, the upper limit float 24 and the lower limit float 25 approach the corresponding reed switches 26 and 27, respectively. Therefore, the contacts of the upper limit reed switch 26 and the lower limit reed switch 27 are both closed.

  As described above, when the lubricating oil is kept within an appropriate amount range, both the upper limit reed switch 26 and the lower limit reed switch 27 are switched on, and the abnormality detection circuit 28 is energized. On the other hand, when the lubricating oil has decreased or increased beyond the appropriate amount range, the upper limit reed switch 26 or the lower limit reed switch 27 is switched to the OFF state, and the abnormality detection circuit 28 is cut off. When the ECU 50 recognizes that the abnormality detection circuit 28 is in the shut-off state and diagnoses that an abnormality in the oil amount of the lubricating oil has occurred, a lighting signal is output from the ECU 50 to the oil amount warning lamp 30. An oil level abnormality is warned to the driver.

  In addition, although what has an upper limit float and a lower limit float was disclosed as an oil level sensor, it is not restricted to this, What kind of form may be sufficient if it is a float type oil level sensor.

  Further, the oil level sensor is not limited to the float type, but may be any type as long as the oil level can be detected, such as a pressure type, an ultrasonic type, and a radio wave type. Furthermore, the means for warning the driver is not limited to the lighting of the oil amount warning lamp 30, and a warning buzzer may be sounded.

  As described above, the oil amount abnormality diagnosis process by the ECU 50 is performed within a setting region that is set by associating the engine speed and the oil temperature with a predetermined correlation. For this reason, the ECU 50 includes a diagnosis execution determination unit 51 and an oil amount abnormality diagnosis unit 52 as shown in FIG. The diagnosis execution determination unit 51 functions as an oil amount detection processing execution determination unit that determines whether or not to perform the oil amount detection processing based on the output value of the oil level sensor 16, and in the present embodiment, The oil amount detection process is a diagnosis process for diagnosing an abnormality in the oil amount of the lubricating oil as an abnormality in the oil level. The oil amount abnormality diagnosing unit 52 diagnoses whether or not the lubricating oil amount is maintained within an appropriate amount range based on the oil level detected from the output value of the oil level sensor 16.

  Specifically, the diagnosis execution determination unit 51 checks whether or not the engine speed N and the oil temperature T are within a set region set with a predetermined correlation. The diagnosis unit 52 is instructed to perform diagnosis, and when outside the set region, the oil amount abnormality diagnosis unit 52 is instructed to stop diagnosis. The diagnosis area for performing the diagnosis is not an area in which the respective ranges are set with the oil temperature of the lubricating oil and the engine speed as independent variables, but an area in which the oil temperature and the engine speed are set in correlation with each other.

  Here, when the engine speed and the oil temperature are constant, when the oil level detected by the oil level sensor 16 and the oil amount are in a substantially proportional relationship, the range of the engine speed and the oil temperature at which diagnosis is performed. As shown in FIG. 4, the engine speed NL to NH (NL <NH) range and the oil temperature TL to TH (TL <TH) range will be described.

  At this time, if the diagnosis region is set with the engine speed and the oil temperature as independent variables, the oil level P of the oil amount Q is uniquely determined under certain conditions (engine speed NL and oil temperature TL). On the other hand, the oil amount obtained from the oil level P detected in the diagnosis region in which the engine speed and the oil temperature are set as independent variables is the oil amount width A1, that is, the engine speed NL and the oil temperature TH. It has a range from the corresponding oil amount to the oil amount corresponding to the engine speed NH and the oil temperature TL. In other words, for the same oil amount Q, the oil level is detected with the oil level detection width B1.

  Therefore, in the present embodiment, when setting the diagnosis region, there is a correlation between the oil temperature and the engine speed, and when the oil temperature is low, the diagnosis is not performed at a high engine speed. The area is set so that the diagnosis is performed by widening the engine speed when the temperature rises. With such a region setting, as shown in FIG. 4, the oil amount width corresponding to the oil surface level P detected by the oil surface sensor 16 is changed from the oil amount width A1 to the oil amount width A2 (A2 <A1). It can be narrowed. For the same oil amount Q, the width of the detected oil level can be narrowed from the oil level detection width B1 to the oil level detection width B2 (B2 <B1).

Specifically, in the two-dimensional region with the oil temperature T as the vertical axis and the engine speed N as the horizontal axis, the engine speed and the oil temperature are independent variables in the range of the engine speed N1 to N2 and the oil temperature T1 to T2. As shown in FIG. 5B, a diagnosis area RB as shown in FIG. 5B is set for the diagnosis area RA of FIG. In the range of the oil temperature T (T1 to T2 ′; T2 ′ <T2), the diagnosis region RB is a region where the engine speed N is lower than the engine speed (area determination threshold) Nd expressed by the following equation (1). This is set as a diagnostic region having a correlation between the oil temperature and the engine speed.
Nd = a × T + b (1)

Equation (1) defines the relationship between the engine speed and the oil temperature with a linear equation of the linear relationship, and the slope a and intercept b of the linear equation are expressed by the following equations (2) and (3), respectively. It is determined.
a = (N2-N1) / (T2'-T1) (2)
b = (N1 × T2′−N2 × T1) / (T2′−T1) (3)

  For example, T1 = 60 [° C.], T2 ′ = 100 [° C.], N1 = 1000 [rpm]. When N2 = 2500 [rpm], a straight line with an inclination a = 37.5 and an intercept b = −1250 in the range of oil temperatures T1 to T2 ′ (T2 ′ <T2; for example, T2 = 120 [° C.]). A diagnosis of abnormality in the amount of lubricating oil is carried out using the region above the diagnosis region as the diagnosis region.

  This avoids misdiagnosis by not performing diagnosis in low oil temperature and high rotation areas where there is a high possibility of erroneous detection, and ensures diagnosis frequency in normal high and low oil temperature areas. An oil amount abnormality can be reliably detected. In addition, even in the low oil temperature region, the detection accuracy can be ensured without significantly reducing the diagnosis frequency, and it is possible to cope with short-time and short-distance operation.

  The oil amount abnormality diagnosis unit 52 diagnoses an abnormality in the oil level, that is, an abnormality in the oil amount of the lubricating oil, based on a signal from the oil level sensor 16 in accordance with a diagnosis execution instruction from the diagnosis execution determination unit 51. When the lubricating oil is higher than the upper limit level Lh or lower than the lower limit level L1, that is, when the amount of lubricating oil is out of the appropriate amount range, the abnormality detection circuit 28 accommodated in the oil level sensor 16 is in a cutoff state. When the interruption state of the abnormality detection circuit 28 is recognized, it is determined that the oil amount is abnormal, and the oil amount warning lamp 30 is turned on.

  Specifically, the above function is realized by a program process of an oil amount abnormality diagnosis executed by the ECU 50. Next, the oil amount abnormality diagnosis program process executed by the ECU 50 will be described with reference to the flowchart shown in FIG.

  The oil amount abnormality diagnosis process shown in the flowchart of FIG. 6 is a program process executed every predetermined time or every predetermined period. First, in step S1, whether or not the oil temperature T of the lubricating oil is equal to or higher than the set temperature T1 on the low temperature side. Find out. As a result, if the oil temperature is low at T <T1, the process branches from step S1 to step S9 to determine that there is no diagnosis, and the process is exited.

  On the other hand, if T ≧ T1 in step S1, it is checked in step S2 whether the oil temperature T is equal to or higher than the set temperature T2 'on the high temperature side. When T <T2 ′, the process proceeds from step S2 to step S3 to check whether or not the engine speed N is equal to or higher than the set speed N1 on the low speed side. If N ≧ N1, the process proceeds to step S4.

  In step S4, it is checked whether or not a condition that the engine speed N is equal to or less than the engine speed (region determination threshold) Nd of the above-described equation (1) defined by the correlation with the oil temperature T is checked. If N> Nd, the process exits from the determination in step S4 to step S9 without diagnosis, and if N ≦ Nd, the process proceeds from step S4 to step S8 for diagnosis. That is, as shown in FIG. 5B described above, when the engine speed N exceeds the region determination threshold value Nd, the engine speed N is outside the diagnosis region RB. If it is equal to or less than the determination threshold value Nd, the diagnosis is performed because it is within the diagnosis region RB.

  On the other hand, if T ≧ T2 ′ in step S2, the process proceeds from step S2 to step S5 to check whether the oil temperature T is equal to or lower than the set temperature T2 (T2> T2 ′). In step S5, if T> T2, it is outside the diagnostic region RB in FIG. 5B, so the diagnosis is not performed (step S9), and this process is skipped. If T ≦ T2, steps S6 and S7 The conditions according to the set speed N1 on the low speed side and the set speed N2 on the high speed side are examined.

  As a result, if N ≧ N1 and the condition of N ≦ N2 is satisfied in step S7, the condition is within the diagnosis region RB of FIG. 5B, so that the diagnosis proceeds from step S6, S7 to step S8. If N <N1 in step S6 or N> N2 in step S7, the process is outside the diagnosis area RB in FIG. 5B, so the process is exited without performing diagnosis (step S9).

  As described above, in the present embodiment, it is determined whether or not the abnormality diagnosis processing is to be performed based on whether or not the engine speed and the oil temperature are within the diagnosis region set by correlating both. If an erroneous diagnosis is prevented in an area where there is a high possibility of occurrence of an oil failure, an abnormality in the oil amount can be reliably detected by ensuring a diagnosis frequency in the normal use area. Further, even when there are many operations in a low oil temperature state for a short time and a short distance, the detection width can be reduced without reducing the diagnosis frequency, which can contribute to the improvement of detection accuracy.

DESCRIPTION OF SYMBOLS 10 Lubricating oil amount detection apparatus 11 Engine 12 Oil pan 16 Oil level sensor 17 Crank angle sensor 18 Oil temperature sensor 50 Electronic control unit 51 Diagnosis execution judgment part (Oil quantity detection processing execution judgment part)
52 Oil quantity abnormality diagnosis part N Engine speed Nd Speed (area judgment threshold)
RB diagnosis area T Oil temperature

Claims (4)

In the engine lubricating oil amount detection device for detecting the oil amount of the lubricating oil based on the oil level of the lubricating oil stored in the engine oil pan,
An oil level sensor for detecting an oil level of the lubricating oil in the oil pan;
Whether or not the engine speed and the temperature of the lubricating oil are within a set region set by correlating them with each other and whether or not to perform an oil amount detection process based on the output value of the oil level sensor An oil amount detection device for an engine, comprising: an oil amount detection processing execution determination unit that determines whether or not.   2. The engine lubricating oil amount detection device according to claim 1, wherein the setting region is a region set using a linear relational expression between the engine speed and the temperature of the lubricating oil.   The engine oil quantity detection device according to claim 1 or 2, wherein the oil quantity detection process is a diagnosis process for diagnosing an oil quantity abnormality of the lubricating oil as an abnormality of the oil level.   The oil level sensor is a float type switch including a float that moves up and down according to an oil level of the lubricating oil and a switch that opens and closes according to the vertical movement of the float. The engine lubricating oil amount detection device according to any one of?

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