JP2021092177A - Oil amount detector - Google Patents

Abstract

To detect a decrease in an oil amount quickly.SOLUTION: An electronic control unit detects a decrease in an oil amount S (step S80) when a vehicle acceleration G detected by an acceleration sensor is less than an upper limit acceleration GZ (step S40: YES), and an oil pressure P detected by an oil pressure sensor is less than a determination oil pressure PZ defined as a value lower than a target oil pressure determined according to the operating state of an internal combustion engine (step S50: YES).SELECTED DRAWING: Figure 3

Description

The present invention relates to an oil amount detecting device.

The internal combustion engine disclosed in Patent Document 1 includes an oil pan in which oil is stored. Inside the oil pan, a temperature detector for detecting the oil temperature of the oil is arranged. The temperature detector includes a temperature sensor and a heat transfer member extending from the temperature sensor to the bottom side of the oil pan. The temperature detected by the temperature sensor of such a thermometer is equal to the oil temperature when the amount of oil is large and the temperature sensor is submerged in oil. On the other hand, when the amount of oil is small and only a part of the heat transfer member is submerged in oil, the amount of heat transferred to the temperature sensor decreases due to heat release in the part of the heat transfer member exposed from the oil. To do. Therefore, the temperature detected by the temperature sensor is lower than the oil temperature.

The control device of the internal combustion engine stores in advance the relationship between the amount of oil and the temperature expected to be detected by the temperature sensor for each of the states where the oil level is horizontal and the oil level is inclined in the oil pan. ing. Then, the control device detects a decrease in the amount of oil by comparing the inclination of the oil level based on the acceleration applied to the internal combustion engine and the temperature detected by the temperature sensor with the above relationship.

Japanese Unexamined Patent Publication No. 2013-002321

Since the technique of Patent Document 1 uses a thermometer that transfers heat from the heat transfer member to the temperature sensor, the amount of oil is detected after waiting for heat to be transferred from the heat transfer member to the temperature sensor. become. Since it takes a considerable amount of time for heat to be transferred from the heat transfer member to the temperature sensor, it takes a considerable amount of time to properly detect the amount of oil.

The oil amount detecting device for solving the above-mentioned problems includes a strainer that sucks the oil stored in the oil pan, and an oil pump to which the strainer is connected and the oil is introduced through the strainer. An oil pressure sensor that is applied to the internal combustion engine and detects the oil pressure of the oil discharged from the oil pump, an acceleration sensor that detects the acceleration of the vehicle on which the internal combustion engine is mounted, and the acceleration of the vehicle detected by the acceleration sensor. Is less than the upper limit acceleration, and the oil pressure detected by the oil pressure sensor is less than the judgment oil pressure defined as a value lower than the target oil pressure determined according to the operating state of the internal combustion engine. It is provided with a detection unit for detecting a decrease.

As the vehicle brakes or turns, the oil level in the oil pan tilts. If the oil level is tilted when the amount of oil in the oil pan is small, the amount of oil in the vicinity of the strainer can be excessively small. In this case, air is sucked from the strainer together with the oil, and the oil pressure discharged from the oil pump is lowered. Utilizing this characteristic, in the above configuration, when the oil level is less than the determined oil level when a corresponding inclination of the oil level is expected, a decrease in the amount of oil is detected. With such a method for determining the amount of oil pressure, a decrease in the amount of oil can be quickly detected. Moreover, the determination oil pressure is not uniformly determined regardless of the operating state of the internal combustion engine, but is variably determined based on the target oil pressure according to the operating state of the internal combustion engine. By using such a judgment oil pressure as a reference, a decrease in the amount of oil can be appropriately detected. Further, if the acceleration of the vehicle is excessively large and the inclination of the oil level becomes extremely large, even if the amount of oil is correspondingly large, the amount of oil in the vicinity of the strainer becomes excessively small and the oil pressure detected by the oil pressure sensor decreases. obtain. In the above configuration, since the upper limit value of the acceleration of the vehicle is set in determining the decrease in the oil amount, it is possible to prevent erroneous detection of the decrease in the oil amount due to the large inclination of the oil level.

Schematic diagram of an internal combustion engine to which an oil amount detector is applied. The figure which showed the example of the oil amount characteristic map. The flowchart which showed the processing procedure of the oil amount drop detection processing.

Hereinafter, an embodiment of an internal combustion engine to which the oil amount detecting device is applied will be described with reference to the drawings.
First, a schematic configuration of an internal combustion engine and an oil supply system will be described.
As shown in FIG. 1, the vehicle 500 is equipped with an internal combustion engine 10 that is a drive source for the vehicle 500. The internal combustion engine 10 includes a cylinder block 22 in which cylinders (not shown) are partitioned. The cylinder block 22 has a substantially rectangular parallelepiped shape as a whole. On the lower end surface of the cylinder block 22, a crankshaft 12 extending in one direction (front and back directions of the paper surface in FIG. 1) as a whole is arranged. The crankshaft 12 is rotatably supported between the lower end surface of the cylinder block 22 and the crank cap attached to the cylinder block 22. The crankshaft 12 rotates in response to the combustion of fuel in the cylinder. A crank angle sensor 50 that detects the rotation position CA of the crankshaft 12 is arranged in the vicinity of the crankshaft 12.

An oil pan 24 is fixed to the lower end surface of the cylinder block 22 with a crankshaft 12 interposed therebetween. The oil pan 24 has a bottomed box shape. Oil for lubricating the internal combustion engine 10 is stored inside the oil pan 24. Further, a strainer 15 for sucking oil is arranged inside the oil pan 24. The suction port 15a of the strainer 15 faces the bottom surface of the oil pan 24. The end of the strainer 15 opposite to the suction port 15a is connected to an oil pump 30 that pumps oil. Then, an oil flow passage 18 that connects to various parts of the internal combustion engine 10 that require lubrication extends from the oil pump 30. An oil pressure sensor 51 that detects the oil pressure P of the oil discharged from the oil pump 30 is arranged in the middle of the oil flow passage 18. Further, an oil temperature sensor 52 for detecting the oil temperature T of the oil discharged from the oil pump 30 is arranged in the middle of the oil flow passage 18. In FIG. 1, the oil flow passage 18 is shown in a simplified diagram by a solid arrow.

In the housing 32 of the oil pump 30, a suction port 32a for sucking oil is defined in the housing 32. The suction port 32a communicates with the strainer 15. Further, the housing 32 is partitioned with a discharge port 32b for discharging oil to the outside of the housing 32. The discharge port 32b communicates with the oil flow passage 18.

The oil pump 30 is an inscribed trochoid type pump that operates with the rotation of the crankshaft 12 of the internal combustion engine 10. That is, a drive shaft 33 that rotates in synchronization with the crankshaft 12 is arranged in the housing 32 of the oil pump 30. A substantially annular inner rotor 34 is fixed to the outer circumference of the drive shaft 33. The inner rotor 34 rotates integrally with the drive shaft 33. A plurality of teeth are provided on the outer periphery of the inner rotor 34 at equal intervals in the circumferential direction.

A substantially annular outer rotor 36 is arranged on the outer side in the radial direction of the inner rotor 34. A plurality of teeth are provided on the inner circumference of the outer rotor 36 at equal intervals in the circumferential direction. The number of teeth of the outer rotor 36 is one more than the number of teeth of the inner rotor 34.

The outer rotor 36 is arranged so that the central axis of the outer rotor 36 is eccentric with respect to the central axis of the inner rotor 34. Of the plurality of teeth of the outer rotor 36, the tooth on the side opposite to the side on which the outer rotor 36 is eccentric with respect to the inner rotor 34 meshes with the teeth of the inner rotor 34. On the other hand, of the plurality of teeth of the outer rotor 36, the teeth on the side where the outer rotor 36 is eccentric with respect to the inner rotor 34 are arranged with a gap between the teeth of the inner rotor 34. This gap is an oil holding chamber 30a for holding oil.

When the inner rotor 34 and the outer rotor 36 rotate, the volume of the oil holding chamber 30a gradually increases or decreases as the inner rotor 34 and the outer rotor 36 rotate. The oil holding chamber 30a communicates with the suction port 32a at a position where the volume gradually increases. Further, the oil holding chamber 30a communicates with the discharge port 32b at a position where the volume gradually decreases. The inner rotor 34 rotates together with the drive shaft 33, and when the inner rotor 34 rotates, the outer rotor 36 rotates by engaging with the teeth of the inner rotor 34.

An annular adjusting ring 38 is arranged on the outer side of the outer rotor 36 in the radial direction as a whole. The inner circumference of the adjusting ring 38 supports the outer circumference of the outer rotor 36 so as to be relatively rotatable. Although not shown, the oil pump 30 is provided with a supply / discharge mechanism for supplying / discharging hydraulic oil to the space between the outer circumference of the adjusting ring 38 and the inner surface of the housing 32. The supply / discharge mechanism, together with the adjusting ring 38, displaces the center axis position of the outer rotor 36 with respect to the center axis position of the inner rotor 34 through the supply / discharge of hydraulic oil. Along with this displacement, the relative position of the portion where the teeth of the outer rotor 36 and the teeth of the inner rotor 34 mesh with each other with respect to the openings of the suction port 32a and the discharge port 32b is changed. Then, the amount of oil discharged per rotation of the drive shaft 33 is changed. As described above, the oil pump 30 has a variable capacity.

Next, the control configuration of the internal combustion engine 10 will be described.
The internal combustion engine 10 is controlled by an electronic control unit 100 mounted on the vehicle 500. The electronic control unit 100 may be configured as one or more processors that execute various processes according to a computer program (software). The electronic control unit 100 includes one or more dedicated hardware circuits such as an application specific integrated circuit (ASIC) that executes at least a part of various processes, or a circuit (cyclery) containing a combination thereof. ) May be configured. The processor includes a CPU and a memory such as RAM and ROM. The memory stores a program code or instruction configured to cause the CPU to execute the process. Memory or computer-readable medium includes any available medium accessible by a general purpose or dedicated computer.

The oil pressure P detected by the oil pressure sensor 51 is input to the electronic control unit 100. Further, the oil temperature T detected by the oil temperature sensor 52 is input to the electronic control unit 100. Further, the electronic control unit 100 is input with the acceleration in the front-rear direction and the acceleration in the left-right direction of the vehicle detected by the acceleration sensor 58 attached to the vehicle 500. The electronic control unit 100 calculates the horizontal acceleration of the vehicle (hereinafter, simply referred to as vehicle acceleration G) as a value obtained by combining the acceleration in the front-rear direction and the acceleration in the left-right direction of the vehicle. Further, the rotation position CA of the crankshaft 12 detected by the crank angle sensor 50 is input to the electronic control unit 100. The electronic control unit 100 calculates the engine speed NE, which is the number of revolutions of the crankshaft 12 per unit time, based on the rotation position CA of the crankshaft 12.

The electronic control unit 100 stores in advance a target oil pressure map for controlling the oil pump 30. The target oil pressure map shows the target value of the oil pressure P to be discharged from the oil pump 30 (hereinafter, referred to as the target oil pressure PA) according to the operating state of the internal combustion engine 10. In this embodiment, the parameters representing the operating state of the internal combustion engine 10 are the engine speed NE and the oil temperature T. Then, in the target oil pressure map, the target oil pressure PA is set for each operating region defined by the engine speed NE and the oil temperature T. Here, the required amount of oil required in various parts of the internal combustion engine 10 changes according to the engine speed NE. Further, the viscosity of the oil changes according to the oil temperature T. In the target oil pressure map, the target oil pressure PA corresponding to the required amount of oil and the viscosity of the oil for each operation area is set for each operation area. The electronic control unit 100 determines the target oil pressure PA according to the current engine rotation speed NE and the oil temperature T with reference to this target oil pressure map, and the oil pressure P of the oil discharged from the oil pump 30 becomes the target oil pressure PA. The oil pump 30 is controlled so as to be.

The electronic control unit 100 includes a detection unit 72 that detects a decrease in the amount of oil S in the oil pan 24. The decrease in the amount of oil S corresponds to the decrease in the oil level, which is an index of the amount of oil S. The basic principle of detecting a decrease in the amount of oil S by the detection unit 72 is as follows. As the vehicle 500 brakes or turns, the oil level Q in the oil pan 24 is tilted. As shown by the alternate long and short dash line in FIG. 1, if the oil level Q is tilted when the amount of oil S in the oil pan 24 is correspondingly small, the amount of oil S in the vicinity of the suction port 15a of the strainer 15 is excessively small. Therefore, a situation may occur in which the entire suction port 15a is not submerged in oil. In this case, air is sucked together with the oil from the suction port 15a, and the oil pressure P of the oil discharged from the oil pump 30 decreases. The detection unit 72 uses this characteristic to detect a decrease in the amount of oil S. That is, the detection unit 72 detects a decrease in the amount of oil S when the oil pressure P is less than the determination oil pressure PZ when a corresponding inclination of the oil level Q is expected.

The detection unit 72 treats the vehicle acceleration G, which is a value reflecting the braking and turning of the vehicle 500, as an index representing the inclination of the oil level Q. Here, if the vehicle acceleration G is excessively large and the inclination of the oil level Q becomes extremely large, even if the oil amount S is correspondingly large, the oil amount S in the vicinity of the suction port 15a of the strainer 15 becomes excessively small. The oil pressure P detected by the oil pressure sensor 51 may decrease. In order to prevent such erroneous detection of a decrease in the amount of oil S due to an extremely large inclination of the oil level Q, the detection unit 72 determines the amount of oil on the condition that the vehicle acceleration G is less than the upper limit acceleration GZ. A decrease in S is detected.

The electronic control unit 100 includes a determination value determination unit 74 for determining the determination oil pressure PZ and the upper limit acceleration GZ. The determination value determination unit 74 stores in advance a determination oil pressure map that defines the determination oil pressure PZ for each operating area that is the same as the target oil pressure map. Further, the determination value determination unit 74 stores in advance an upper limit acceleration map in which the upper limit acceleration GZ is defined for each operating region that is the same as the target oil pressure map. The determination value determination unit 74 determines the determination oil pressure PZ according to the current engine speed NE and the oil temperature T with reference to the determination oil pressure map during the operation of the internal combustion engine 10. Further, the determination value determining unit 74 determines the upper limit acceleration GZ according to the current engine speed NE and the oil temperature T with reference to the upper limit acceleration map during the operation of the internal combustion engine 10.

The judgment oil pressure map and the upper limit acceleration map stored in the judgment value determination unit 74, that is, the judgment oil pressure PZ and the upper limit acceleration GZ for each operation area are determined by using the oil amount characteristic map created for each operation area. There is. As shown in FIG. 2, the oil amount characteristic map shows the relationship between the oil pressure P, the vehicle acceleration G, and the oil amount S, and has been created by experiments and simulations. In each oil amount characteristic map, for example, the oil amount S is defined in a Cartesian coordinate system having the oil pressure P and the vehicle acceleration G as coordinate axes. In FIG. 2, the larger the amount of oil S, the thicker the isobaric amount line. Here, as described above, when the oil level Q is tilted, the amount of oil S in the vicinity of the suction port 15a of the strainer 15 decreases, and the oil pressure P decreases. The larger the inclination of the oil level Q at this time, the smaller the amount of oil S in the vicinity of the suction port 15a and the easier it is to suck in air, so that the oil pressure P becomes lower. Reflecting such a relationship, in each oil amount characteristic map, the oil pressure P becomes lower as the vehicle acceleration G becomes larger for a specific oil amount SZ. Further, as a general characteristic, if the inclination of the oil level Q is the same, the smaller the amount of oil S, the smaller the amount of oil in the vicinity of the suction port 15a of the strainer 15, and the lower the oil pressure P. Reflecting this relationship, in each oil amount characteristic map, the smaller the oil amount S, the lower the oil pressure P with respect to the specific vehicle acceleration G. From the viewpoint of the amount of oil S with respect to the oil pressure P and the vehicle acceleration G, in each oil amount characteristic map, the larger the vehicle acceleration G and the higher the oil pressure P, the larger the oil amount S. Regarding the difference in the oil amount characteristic map for each operating region, for example, when comparing the map of the operating region where the oil temperature T is high and the map of the operating region where the oil temperature T is low, the lower the oil temperature T, the more the oil. Due to the higher viscosity and higher oil pressure P, the oil pressure P corresponding to the same vehicle acceleration G and the same oil amount S is more in the latter driving area map than in the former driving area map. It's getting higher.

The determination oil pressure PZ and the upper limit acceleration GZ stored in the determination value determination unit 74 are defined so that it can be detected that the oil amount S is less than the specified oil amount SZ by using the oil amount characteristic map. .. In this embodiment, the specified oil amount SZ is set to be slightly higher than the lower limit of the appropriate amount of the oil amount S during the operation of the internal combustion engine 10.

As for the determination oil pressure PZ and the upper limit acceleration GZ stored in the determination value determination unit 74, the determination oil pressure PZ is first determined prior to the upper limit acceleration GZ. Specifically, the determination oil pressure PZ is determined with reference to the target oil pressure PA determined according to the operating state of the internal combustion engine 10. Here, assuming that the oil level Q is not tilted, the oil pressure P of the oil actually discharged from the oil pump 30 with respect to the target oil pressure PA determined according to the operating state of the internal combustion engine 10 is For example, it increases or decreases with respect to the target oil pressure PA due to a deviation of the displacement amount of the outer rotor 36 or the like. Regarding the decrease side in this increase / decrease, when the limit value that can be taken by the actual oil pressure P is set as the minimum limit value, if the oil pressure P that falls below this minimum limit value is detected, such oil pressure P is the oil level. It can be regarded as the oil pressure P which cannot normally occur when Q is not tilted. If the oil level Q is tilted, the oil pressure P may fall below the above minimum limit value due to a decrease in the amount of oil S in the vicinity of the suction port 15a of the strainer 15 due to the tilt. .. That is, when the oil pressure P decreases beyond the above minimum limit value, it is expected that the oil pressure P decreases due to the inclination of the oil level Q. Therefore, in this embodiment, the minimum limit value, which is the lower limit value that the actual oil pressure P can take with respect to the target oil pressure PA in the state where the vehicle acceleration G is zero, is defined as the determination oil pressure PZ. The minimum limit value is determined by experiments and simulations on the premise that the vehicle acceleration G is zero, and is, for example, a value of 70% of the target oil pressure PA.

The upper limit acceleration GZ stored in the determination value determination unit 74 is determined from the balance with the determination oil pressure PZ by using the oil amount characteristic map. As described above, in the oil amount characteristic map, the larger the vehicle acceleration G, the larger the oil amount S. Therefore, in the oil amount characteristic map, the oil amount S exceeds the specified oil amount SZ in the region B in which the oil pressure P is less than the determination oil pressure PZ and the vehicle acceleration G is correspondingly high. The upper limit acceleration GZ is set so that such a region can be excluded from the detection region of the decrease in oil amount. In this embodiment, the upper limit acceleration GZ is defined as the vehicle acceleration G corresponding to the determined oil amount PZ and the specified oil amount SZ on the oil amount characteristic map. In the oil amount characteristic map, the region where the vehicle acceleration G is less than the upper limit acceleration GZ and the oil pressure P is less than the determination oil pressure PZ is the oil amount decrease detection region W.

As shown in FIG. 1, the electronic control unit 100 includes a warning light control unit 70 that controls a warning light 81 for reducing the amount of oil attached to the vehicle. When a signal for switching the warning light 81 to the lighting state is input, the warning light control unit 70 switches the warning light 81 to the lighting state. When a signal for switching the warning light 81 to the off state is input, the warning light control unit 70 switches the warning light 81 to the off state. The signal for switching the warning light 81 to the lighting state is input to the warning light control unit 70 in the oil amount decrease detection process described later. A signal for switching the warning light 81 to the extinguished state is input to the warning light control unit 70 when, for example, oil is replenished and it is detected that the amount of oil S is an appropriate amount. The warning lamp 81 is, for example, an indicator lamp built in the meter panel in the vehicle interior. In this embodiment, the electronic control unit 100, the crank angle sensor 50, the oil pressure sensor 51, the oil temperature sensor 52, and the acceleration sensor 58 constitute an oil amount detecting device.

Next, the oil amount decrease detection process executed by the electronic control unit 100 will be described.
During the operation of the internal combustion engine 10, the electronic control unit 100 repeatedly executes the oil amount reduction process, which is a process for detecting a decrease in the oil amount S. As shown in FIG. 3, when the electronic control unit 100 starts the oil amount reduction process, the process of step S10 is executed. In step S10, the detection unit 72 initializes the duration H of the oil pressure drop used in the process described later to zero. When the detection unit 72 executes the process of step S10, the detection unit 72 advances the process to step S20.

In step S20, the detection unit 72 of the electronic control unit 100 determines whether or not the warning light 81 is in the extinguished state. When the warning light 81 is in the lit state (step S20: NO), the detection unit 72 temporarily ends a series of processes for detecting the decrease in oil amount. In this case, the detection unit 72 executes the process of step S10 again.

On the other hand, in step S20, when the warning light 81 is off (step S20: YES), the detection unit 72 proceeds to step S30.
In step S30, the determination value determination unit 74 determines the determination oil pressure PZ according to the current engine speed NE and the oil temperature T with reference to the determination oil pressure map. Further, the determination value determination unit 74 determines the upper limit acceleration GZ according to the current engine speed NE and the oil temperature T with reference to the upper limit acceleration map. When the determination value determination unit 74 executes the process of step S30, the process proceeds to step S40.

In step S40, the detection unit 72 determines whether or not the current vehicle acceleration G is less than the upper limit acceleration GZ. When the vehicle acceleration G is equal to or higher than the upper limit acceleration GZ (step S40: NO), the detection unit 72 temporarily ends a series of processes for detecting the decrease in oil amount. In this case, the detection unit 72 executes the process of step S10 again.

On the other hand, in step S40, when the vehicle acceleration G is less than the upper limit acceleration GZ (step S40: YES), the detection unit 72 proceeds to step S50.
In step S50, the detection unit 72 determines whether or not the current oil pressure P is less than the determination oil pressure PZ. When the oil pressure P is equal to or higher than the determination oil pressure PZ (step S50: NO), the detection unit 72 temporarily ends a series of processes for detecting the decrease in oil amount. In this case, the detection unit 72 executes the process of step S10 again.

On the other hand, in step S50, when the oil pressure P is less than the determination oil pressure PZ (step S50: YES), the detection unit 72 advances the process to step S60.
In step S60, the detection unit 72 determines whether or not the duration H of the oil pressure drop is greater than zero. If it is the first time that both step S40 and step S50 become YES after it is determined in step S20 that the warning light 81 is in the extinguished state (step S20: YES), the duration H is zero. When the duration H is zero (step S60: NO), the detection unit 72 advances the process to step S110. Then, in step S110, the detection unit 72 starts counting the duration H of the oil pressure drop. After this, the detection unit 72 proceeds to step S70. Once the detection unit 72 starts counting the duration H of the oil pressure drop, the detection unit 72 continues counting the duration H until the process of step S90 described later is executed.

In step S70, the detection unit 72 determines whether or not the duration H of the oil pressure drop is equal to or longer than the determination time HZ. Here, for example, the oil level Q in the oil pan 24 jumps up or sways due to the momentary jumping of the vehicle due to the unevenness of the road surface, and the amount of oil sucked by the strainer 15 is instantaneously reduced, resulting in a hydraulic pressure. P may decrease. The determination time HZ is set as a time during which the decrease in the oil pressure P due to the continuous inclination of the oil level Q can be detected separately from such an instantaneous decrease in the oil pressure P, for example, several seconds. When the duration H of the oil pressure drop is less than the determination time HZ (step S70: NO), the detection unit 72 returns to the process of step S30.

When the process returns to step S30, the determination value determination unit 74 determines the determination oil pressure PZ and the upper limit acceleration GZ according to the engine speed NE and the oil pressure P as described above. After that, when the vehicle acceleration G is less than the upper limit acceleration GZ in step S40 (step S40: YES) and the oil pressure P is less than the determination oil pressure PZ in step S50 (step S50: YES), the detection unit 72 performs processing. Proceed to step S60. At this time, since the count of the duration H of the oil pressure drop has already started and the duration H is larger than zero, the detection unit 72 determines that the process of step S60 is YES. If the process in step S60 is determined to be YES, the detection unit 72 skips the process in step S110 and proceeds to the process in step S70. Then, the detection unit 72 compares the duration H with the determination time HZ, and if the duration H is less than the determination time HZ (step S70: NO), returns to the process of step S30 again. In this way, the detection unit 72 repeats the processes of steps S30 to S70.

The detection unit 72 determines in step S40 or in step S50 at a timing before the duration H reaches the determination time HZ (step S70: NO) during the repetition of the processes of steps S30 to S70. That is, when the vehicle acceleration G becomes equal to or higher than the upper limit acceleration GZ (step S40: NO), or the oil pressure P becomes equal to or higher than the judgment hydraulic pressure PZ (step S50: NO), a series of oil amount reduction detection processes The process is terminated once. In this case, the detection unit 72 executes the process of step S10 again.

On the other hand, the detection unit 72 determines the duration H while the vehicle acceleration G is less than the upper limit acceleration GZ (step S40: YES) and the oil pressure P is less than the determination oil pressure PZ (step S50: YES). When the time becomes HZ or more (step S70: YES), the process proceeds to step S80.

In step S80, the detection unit 72 detects a decrease in the amount of oil S and outputs a signal for switching the warning light 81 to the lighting state to the warning light control unit 70. Then, the detection unit 72 advances the process to step S90.

In step S90, the detection unit 72 ends counting the duration H of the oil pressure drop. After that, the detection unit 72 ends a series of processes for detecting the decrease in oil amount. Then, the detection unit 72 executes the process of step S10 again.

Next, the operation of this embodiment will be described.
It is assumed that the oil level Q is tilted as the vehicle 500 is braked or turned as shown by the alternate long and short dash line in FIG. 1 during the operation of the internal combustion engine 10. Then, it is assumed that a part of the suction port 15a of the strainer 15 is exposed from the oil level Q. If the vehicle acceleration G at this time is less than the upper limit acceleration GZ (step S40: YES) and the oil pressure P is less than the determination oil pressure PZ (step S50: YES), the count of the duration H of the oil pressure drop is started. (Step S110). When the vehicle acceleration G is less than the upper limit acceleration GZ and the state where the oil pressure P is less than the judgment oil pressure PZ continues for the judgment time HZ or more (step S70: YES), a decrease in the oil amount S is detected and the warning light 81 lights up. (Step S80).

Next, the effect of this embodiment will be described.
(1) In the above configuration, when the decrease in the oil level P continues for the determination time HZ or more under the condition that the oil level Q has a corresponding inclination, the decrease in the oil amount S is detected. The determination time HZ is a time scale of several seconds. Therefore, a decrease in the amount of oil S can be quickly detected on a considerably short time scale of several seconds.

(2) In the above configuration, the determination oil level PZ is a lower limit value that the actual oil level P can take with respect to the target oil level PA with no inclination of the oil level Q. Here, since the target oil pressure PA is set as a value suitable for each operating area, the determination hydraulic pressure PZ determined based on the target oil pressure PA is also set as a value suitable for each operating area. In this way, by setting the determination oil pressure PZ variably according to the operation state of the internal combustion engine 10 instead of setting the determination oil pressure PZ uniformly regardless of the operating state of the internal combustion engine 10, it is suitable for each operating region. The determination oil pressure PZ can be set, and a decrease in the amount of oil S can be appropriately detected in each operating region.

By the way, as an oil pump, there is a constant-capacity type that does not have an adjusting ring or a hydraulic oil supply / discharge mechanism. In such a type of oil pump, since the target oil pressure is not specified, the lower limit value that the oil pressure can take in each operating region without the inclination of the oil level Q may vary greatly from product to product. If there is a large variation among products, it is difficult to set a judgment oil pressure suitable for all products.

In this respect, the target oil pressure PA is specified in the variable capacity oil pump 30 used in the above embodiment. When the target oil pressure PA is determined, the range that the actual oil pressure P can take in each operating region without the inclination of the oil level Q falls within a certain range centered on the target oil pressure PA. Therefore, the variation among products becomes small with respect to the lower limit value that the actual oil pressure P can take. Therefore, the optimum determination hydraulic pressure PZ for all products can be easily determined.

(3) Even when the amount of oil S is sufficient, if the inclination of the oil level Q becomes excessively large, the amount of oil S in the vicinity of the suction port 15a of the strainer 15 becomes excessively small, and the oil pressure P may decrease. Therefore, in the above configuration, the upper limit acceleration GZ is set for detecting the oil amount S. Therefore, it is possible to prevent erroneous detection of a decrease in the amount of oil S due to a large inclination of the oil level Q. Moreover, in the above configuration, since the upper limit acceleration GZ is set for each operating region, the upper limit acceleration GZ suitable for each operating region can be set.

(4) In the above configuration, the oil amount S is reduced by using the detection values of the existing sensors mounted on the vehicle 500 such as the oil pressure sensor 51, the oil temperature sensor 52, the acceleration sensor 58, and the crank angle sensor 50. It is being detected. With such a configuration using an existing sensor, the number of parts does not increase in detecting a decrease in the amount of oil S.

In addition, this embodiment can be implemented by changing as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
-The processing content of the oil amount reduction detection process is not limited to the example of the above embodiment. The oil amount decrease detection process may include the content of detecting that the oil amount S has decreased when the vehicle acceleration G is less than the upper limit acceleration GZ and the oil pressure P is less than the determination oil pressure PZ. For example, the method of determining the determination oil pressure PZ may be changed. For example, regarding the lower limit value that the actual oil pressure P can take with respect to the target oil level PA when the oil level Q is not tilted, when the ratio of the lower limit value to the target oil level PA is set as the lower limit value ratio, the lower limit value ratio If is determined to be a substantially constant value regardless of the operating area, the determination value determining unit 74 may store the constant lower limit value ratio in advance. Then, when determining the determination oil pressure PZ, the determination oil pressure PZ may be calculated by multiplying the target oil pressure PA according to the operating state of the internal combustion engine 10 by the above lower limit value ratio.

The determination value determination unit 74 may store the oil amount characteristic map for each operating region and determine the oil amount decrease detection region W on the oil amount characteristic map in the processing process of the oil amount decrease detection process. Then, even if the detection unit 72 detects the decrease in the oil amount S when the detected oil pressure P and the vehicle acceleration G are values within the detection region W of the oil amount decrease on the oil amount characteristic map. Good. In such a method of detecting a decrease in the amount of oil S on the oil amount characteristic map, the upper limit acceleration GZ is not set to a constant value for each of the operating regions, for example, on the oil amount characteristic map. It is also possible to determine a region in which the upper limit acceleration GZ is variable according to the oil pressure P, such that the upper limit acceleration GZ is increased as the oil pressure P becomes lower.

-The upper limit acceleration GZ may not be set for each operating region, but the upper limit acceleration GZ may be set to a uniform value regardless of the operating region. If the inclination of the extreme oil level Q that causes a false detection of a decrease in the amount of oil S is determined to be a substantially constant inclination angle, the vehicle acceleration G corresponding to the inclination angle is determined in advance by experiments or simulations. , The vehicle acceleration G may be set as a uniform upper limit acceleration GZ regardless of the driving area.

-As a condition for detecting a decrease in the amount of oil S, it may be added that the vehicle acceleration G is equal to or higher than the lower limit acceleration larger than zero. Then, a decrease in the amount of oil S may be detected on condition that the oil level Q is surely tilted.

-As a condition for detecting a decrease in the amount of oil S, it may be added that the oil pressure P is equal to or higher than the lower limit oil pressure larger than zero. Here, when the oil pressure P is extremely low, a factor other than the decrease in the amount of oil S, such as a malfunction of the oil pump 30, may be the cause of the decrease in the oil pressure P. Therefore, if the lower limit oil pressure is set as a condition for detecting the decrease in the oil amount S, it is possible to prevent erroneous detection of the decrease in the oil pressure P due to a factor other than the decrease in the oil amount S as the decrease in the oil amount S.

The determination oil level PZ does not have to be the lower limit value that the actual oil level P can take with respect to the target oil level PA in a state where the oil level Q is not tilted. For example, the determination oil pressure PZ may be set as a value correspondingly lower than the lower limit value that the actual oil pressure P can take with respect to the target oil pressure PA in a state where the oil level Q is not tilted. The determination oil pressure PZ may be a value lower than the target oil pressure PA and a value that can detect a decrease in the amount of oil S.

-The specified oil amount SZ is not limited to the example of the above embodiment. The specified oil amount SZ may be determined according to the oil amount S for which a warning is required.
The parameters representing the operating state of the internal combustion engine 10 are not limited to the example of the above embodiment. As a parameter representing the operating state of the internal combustion engine 10, the engine load factor based on, for example, the engine speed NE and the intake air amount may be included in place of or in addition to the parameter of the above embodiment. Then, the operating areas of the various maps may be defined including the engine load factor. Further, for example, the operating region may be defined only by the engine speed NE, that is, by only one parameter.

-As the oil pump, a constant-capacity type that does not have an adjustment ring or a hydraulic oil supply / discharge mechanism may be adopted. The oil pressure discharged from an oil pump with a constant capacity takes a value that is generally determined according to the engine speed and the oil temperature. Therefore, in a constant-capacity oil pump, for example, the average value of the oil pressure for a certain period is calculated for each operating area defined by the engine speed and the oil temperature by experiments and simulations, and such oil pressure is treated as the target oil pressure. May be good. Then, the determination oil pressure may be set as a value lower than this target oil pressure. As described above, in the oil pump having a constant capacity, the lower limit value that the oil pressure can take in the state where the oil level Q is not inclined may vary greatly from product to product in each operating region. Therefore, for example, the lower limit value of the product having the lowest lower limit value may be applied to all products as the determination oil pressure. With such a judgment oil pressure, it can be used as a standard for separating the oil pressure that cannot normally occur when the oil level is not tilted for all products.

-As the oil pump, an electric type driven by an electric motor may be adopted. Since the target oil pressure for controlling the electric motor is specified in the electric oil pump, the judgment oil pressure may be calculated based on this target oil pressure.

-The pump mechanism of the oil pump is not limited to the inscribed trochoid type. For example, an external pump mechanism in which two external gear type gears are meshed with each other may be adopted.
-The overall configuration of the internal combustion engine 10 can be changed as appropriate. For example, the oil pump 30 may be arranged outside the oil pan 24. That is, the oil pump 30 may be arranged in a storage chamber partitioned by an outer surface of the oil pan 24 and a chain case covering the outer surface of the oil pan 24.

10 ... Internal combustion engine 51 ... Oil pressure sensor 52 ... Oil temperature sensor 58 ... Accelerometer 72 ... Detection unit 74 ... Judgment value determination unit 100 ... Electronic control unit 500 ... Vehicle

Claims (1)

It is applied to an internal combustion engine having a strainer for sucking oil stored in an oil pan and an oil pump to which the strainer is connected and oil is introduced through the strainer.
An oil pressure sensor that detects the oil pressure of the oil discharged from the oil pump, and
An acceleration sensor that detects the acceleration of a vehicle equipped with an internal combustion engine,
The acceleration of the vehicle detected by the acceleration sensor is less than the upper limit acceleration, and the oil pressure detected by the oil pressure sensor is set as a value lower than the target oil pressure determined according to the operating state of the internal combustion engine. An oil amount detection device including a detection unit that detects a decrease in the oil amount when the pressure is less than the judgment oil pressure.

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