Oil amount determination device

Abstract

To suppress wrong determination of lowering of an oil amount even when an oil type differs.SOLUTION: An oil amount determination device includes: a strainer 15 that sucks oil stores in an oil pan 24 of an internal combustion engine 10; a fixed displacement type oil pump 30 to which oil is introduced via the strainer 15; a hydraulic sensor 51 for detecting hydraulic pressure of oil discharged from the oil pump 30; and a control device 100. The control device 100 executes processing of: determining lowering of an amount of the oil stored in the oil pan 24 when the hydraulic pressure detected by the hydraulic sensor 51 is equal to or lower than prescribed determination hydraulic pressure; and acquiring a parameter related to viscosity of the oil during an operation of the engine and setting the determination hydraulic pressure on the basis of the acquired parameter.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an oil amount determining device. [Background technology]

[0002] For example, the oil level determination device described in Patent Document 1 determines that the amount of oil stored in the oil pan has decreased if the oil pressure of the oil discharged from the oil pump is lower than a predetermined determination oil pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-182457 Summary of the Invention [Problem to be solved by the invention]

[0004] In the case of a fixed displacement oil pump, the discharge pressure is determined by the rotational speed of the oil pump and the viscosity of the oil. Since the viscosity of oil varies depending on the type of oil, the detected oil pressure will also vary depending on the type of oil stored in the oil pan. Therefore, if the above-mentioned threshold oil pressure is not set appropriately, an erroneous determination of low oil level may occur. [Means for solving the problem]

[0005] An oil level determination device that solves the above problem includes a strainer that draws oil stored in an oil pan of an internal combustion engine, a fixed displacement oil pump into which the oil is introduced via the strainer, a hydraulic pressure sensor that detects the hydraulic pressure of the oil discharged from the oil pump, and a control device. The control device executes the following processes: determining that the amount of oil stored in the oil pan is low when the hydraulic pressure detected by the hydraulic pressure sensor is equal to or lower than a predetermined threshold hydraulic pressure; and acquiring parameters related to the viscosity of the oil during engine operation and setting the threshold hydraulic pressure based on the acquired parameters. [Effects of the Invention]

[0006] This oil level determination device can prevent erroneous determination of low oil level even when different types of oil are used. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of an internal combustion engine to which an oil amount determination device is applied. [Figure 2] FIG. 2 is a flowchart showing the procedure of processing executed by the control device of the embodiment. [Figure 3] FIG. 3 is a diagram showing the correspondence relationship between the engine rotation speed and the determined oil pressure in the determined oil pressure setting map of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of an internal combustion engine to which an oil amount determination device is applied will be described with reference to the drawings. <Configuration of the internal combustion engine and oil supply system> 1, a vehicle 500 is equipped with an internal combustion engine 10 that serves as a drive source for the vehicle 500. A crank angle sensor 50 that detects a rotational position CA of the crankshaft 12 is disposed near the crankshaft 12 of the internal combustion engine 10.

[0009] An oil pan 24 is fixed to the lower end surface of the cylinder block 22 of the internal combustion engine 10 with the crankshaft 12 sandwiched therebetween. Oil for lubricating the internal combustion engine 10 is stored inside the oil pan 24. A strainer 15 for sucking oil is also disposed inside the oil pan 24.

[0010] The strainer 15 has an intake port 15 a that opens toward 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.

[0011] The oil pump 30 is an internal trochoid fixed displacement pump that operates in conjunction with the rotation of the crankshaft 12 of the internal combustion engine 10. Oil is introduced into the oil pump 30 via a strainer 15.

[0012] An oil flow passage 18 extends from the oil pump 30 to various parts of the internal combustion engine 10 that require lubrication. An oil pressure sensor 51 is disposed in the oil flow passage 18 to detect the oil pressure P of the oil discharged from the oil pump 30. Also disposed in the oil flow passage 18 is an oil temperature sensor 52 that detects the oil temperature THO of the oil discharged from the oil pump 30.

[0013] The operation of the internal combustion engine 10 is controlled by a control device 100. The control device 100 includes a CPU 110 and a memory 120 that stores control programs and data. The CPU 110 executes the programs stored in the memory 120 to perform various control-related processes.

[0014] The control device 100 receives an input of an oil pressure P detected by an oil pressure sensor 51. The control device 100 also receives an input of an oil temperature THO detected by an oil temperature sensor 52. The control device 100 also receives an input of the vehicle's longitudinal acceleration and lateral acceleration detected by an acceleration sensor 58 attached to the vehicle 500. The control device 100 calculates the vehicle's horizontal acceleration (hereinafter simply referred to as vehicle acceleration G) as a composite value of the vehicle's longitudinal acceleration and lateral acceleration. The control device 100 uses the vehicle acceleration G, which reflects the braking and turning of the vehicle 500, as an index representing the inclination of the oil level Q in the oil pan 24. The control device 100 also receives an input of a rotational position CA of the crankshaft 12 detected by a crank angle sensor 50. The control device 100 calculates an engine rotational speed NE, which is the rotational speed of the crankshaft 12 per unit time, based on the rotational position CA. The control device 100 is also connected to a warning light 81 for indicating a low oil level.

[0015] <About the oil level drop detection process> The control device 100 executes an oil level reduction determination process to determine that the oil level S stored in the oil pan 24 has decreased when the oil pressure P detected by the oil pressure sensor 51 is equal to or lower than a predetermined determination oil pressure PZ. The decrease in oil level S corresponds to the oil level, which is an index of the oil level S, being lower than a predetermined lower limit. The control device 100 that executes the oil level reduction determination process constitutes an oil level determination device.

[0016] The basic principle for determining a decrease in oil amount S is a well-known principle as described in Patent Publication No. 2021-92177, Patent Publication No. 2022-182457, Patent Publication No. 2024-20887, etc., and will be outlined below.

[0017] As the vehicle 500 brakes or turns, the oil level Q in the oil pan 24 tilts. As shown by the two-dot chain line in Figure 1, if the oil level Q tilts when the oil volume S in the oil pan 24 is relatively low, the oil volume S near the suction port 15a of the strainer 15 becomes excessively low, resulting in a situation where the entire suction port 15a is not submerged in oil. In this case, air is sucked into the suction port 15a along with the oil, and the oil pressure P of the oil discharged from the oil pump 30 drops. On the other hand, if the slope of the oil level Q decreases and the entire suction port 15a is submerged in oil again, the intake of air through the suction port 15a stops, and the oil pressure P of the oil discharged from the oil pump 30 increases and returns to normal. In this way, when the oil volume S is low, the oil pressure P drops but then recovers, i.e., the oil pressure P temporarily drops.

[0018] Therefore, the control device 100 utilizes this phenomenon to detect a decrease in the oil level S. That is, the control device 100 measures the duration H during which the oil pressure P is equal to or lower than a reference oil pressure PZ set based on the engine speed NE. If the measured duration H is within a predetermined range, the control device 100 determines that the oil pressure P has temporarily decreased, and therefore determines that the oil level S has decreased. If it determines that the oil level S has decreased, the control device 100 turns on the warning light 81. The reference oil pressure PZ is set based on a reference oil pressure map in which a correspondence relationship between the engine speed NE and the reference oil pressure PZ is set. This reference oil pressure map is stored in the memory 120, and the stored value is updated by a reference oil pressure setting process described below.

[0019] <Determined oil pressure setting process> The control device 100 sets the above-mentioned judgment oil pressure PZ as follows. 2 shows the procedure for the judgment oil pressure setting process executed by the control device 100 to set the judgment oil pressure PZ. This process is realized by the control device 100 repeatedly executing it at predetermined intervals while the engine is running. Note that this process is preferably executed when it is determined that no tilt of the oil level Q has occurred by referring to the detection value of the acceleration sensor 58, etc.

[0020] In the following, the step numbers of each process are represented by numbers with "S" attached at the beginning. In the series of processes shown in FIG. 2, the control device 100 first determines whether or not the oil temperature THO is equal to or higher than a predetermined determination value THOref (S100). The determination value THOref is set in advance so that it can be determined that the viscosity of the oil is in a stable state based on the fact that the oil temperature THO is equal to or higher than the determination value THOref. For example, as the determination value THOref, the oil temperature THO when the warm-up of the internal combustion engine 10 is completed can be applied.

[0021] In the process of S100, when it is determined that the oil temperature THO is equal to or higher than the determination value THOref (S100: YES), the control device 100 acquires the current engine speed NE and the oil pressure P (S110). The engine speed NE is a value indicating the rotation speed of the oil pump 30. In the case of the fixed displacement type oil pump 30, the higher the engine speed NE, the higher the oil pressure P. And the magnitude of the oil pressure P at an arbitrary engine speed NE is a value correlated with the viscosity of the oil described above. That is, even at the same engine speed NE, the higher the viscosity of the oil, the higher the oil pressure P at that engine speed NE. Therefore, the oil pressure P detected at an arbitrary engine speed NE is a parameter related to the current viscosity of the oil that the control device 100 acquires during engine operation.

[0022] Next, the control device 100 calculates the above-described determination oil pressure PZ (S120). In the process of S120, the control device 100 calculates a value obtained by multiplying the oil pressure P acquired in the process of S110 by a predetermined coefficient K. Then, the calculated value is substituted into the determination oil pressure PZ. The coefficient K is a value that has been adapted in advance for determining the decrease in the amount of oil, and is a predetermined value satisfying "0 < K < 1". For example, the coefficient K is a value such as "0.4" or "0.7". Also, this coefficient K may be changed according to the engine speed NE.

[0023] Next, the control device 100 updates the judgment oil pressure PZ (S130). In the processing of S130, the control device 100 updates the judgment oil pressure PZ stored in the judgment oil pressure map by overwriting the judgment oil pressure PZ calculated in S120 as the judgment oil pressure PZ corresponding to the engine rotation speed NE obtained in S110. By updating the judgment oil pressure PZ in this way at various engine rotation speeds NE, the value of the judgment oil pressure map in which the correspondence relationship between the engine rotation speed NE and the judgment oil pressure PZ is set is updated.

[0024] When the process of S130 is completed or when a negative determination is made in the process of S100, the control device 100 temporarily ends the series of processes shown in FIG. <Operation of this embodiment> Fig. 3 shows the relationship between the engine rotation speed NE and the judgment oil pressure PZ in the judgment oil pressure setting map. Note that the solid line L1 in Fig. 3 shows this relationship when oil A, which has a high viscosity, is stored in the oil pan 24. Furthermore, the dashed-dotted line L2 in Fig. 3 shows this relationship when oil B, which has a lower viscosity than oil A, is stored in the oil pan 24.

[0025] As shown in the figure, the higher the engine speed NE, the higher the pressure at which the judgment oil pressure PZ is set. Also, even at the same engine speed NE, if high-viscosity oil A is stored in the oil pan 24, the judgment oil pressure PZ is set to a higher pressure than if low-viscosity oil B is stored therein.

[0026] <Effects of this embodiment> (1) The control device 100 executes a process to determine that the amount S of oil stored in the oil pan 24 has decreased when the oil pressure P is equal to or lower than the threshold oil pressure PZ. The control device 100 then acquires parameters related to the oil viscosity during engine operation and executes a process to set the threshold oil pressure PZ based on the acquired parameters. Therefore, the threshold oil pressure PZ is set based on the parameters related to the oil viscosity acquired during engine operation. Therefore, the threshold oil pressure PZ is set according to the type of oil stored in the oil pan 24. Therefore, even if the type of oil stored in the oil pan 24 is different, an appropriate threshold oil pressure PZ is set according to the viscosity of that oil type. Therefore, even if the type of oil is different, erroneous determination of a decrease in oil amount can be suppressed.

[0027] (2) When the oil temperature THO is equal to or higher than the reference value THOref, the control device 100 updates the reference oil pressure PZ. Therefore, it is possible to set an appropriate reference oil pressure PZ, taking into consideration that the oil pressure P changes due to changes in oil viscosity caused by the oil temperature THO.

[0028] <Example of change> The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0029] When the oil in the oil pan 24 is changed, a process may be executed to reset the judgment oil pressure PZ. For example, a process may be executed to return the judgment oil pressure PZ set in the judgment oil pressure setting map to a pre-adjusted initial value. In this case, it is possible to prevent a false determination that the oil level is low due to a large drop in oil pressure, for example, when changing from high-viscosity oil to low-viscosity oil.

[0030] The determination oil pressure setting process may be executed only when the vehicle is stopped and prohibited when the vehicle is moving. In this case, it is possible to suppress the influence of fluctuations in the engine speed NE and fluctuations in the oil pressure P due to the behavior of the vehicle 500 on the setting of the determination oil pressure PZ. In this modified example, it is preferable to execute the oil level reduction determination process when the vehicle is stopped.

[0031] The judgment oil pressure setting map is a map showing the correspondence relationship between the engine speed NE and the judgment oil pressure PZ. Alternatively, for example, the oil pressure P obtained in the process of S110 shown in FIG. 2 is used as the reference oil pressure. Then, the combination of the engine speed NE and the reference oil pressure obtained in the process of S110 is saved in a map prepared in the memory 120. Then, when comparing the oil pressure P and the judgment oil pressure PZ in the oil level reduction judgment process, the reference oil pressure corresponding to the engine speed NE at that time may be read from the map, and the read reference oil pressure may be multiplied by the coefficient K to calculate the judgment oil pressure PZ.

[0032] The oil pump 30 may be a pump other than an inscribed trochoid type. The oil pump 30 may be an electric oil pump. In this case, the rotation speed of the oil pump may be acquired instead of the engine rotation speed NE in the process of S110 shown in FIG. [Explanation of symbols]

[0033] 10...Internal combustion engine 12...Crankshaft 15...Strainer 15a...Inlet 18...Oil flow passage 22...Cylinder block 24...Oil pan 30...Oil pump 50...Crank angle sensor 51...Oil pressure sensor 52...Oil temperature sensor 58...Acceleration sensor 81...Warning light 100...Control device 110...CPU 120...Memory 500...vehicle

Claims

[Claim 1] An oil amount determination device having a strainer that draws oil stored in an oil pan of an internal combustion engine, a fixed displacement oil pump into which the oil is introduced through the strainer, a hydraulic pressure sensor that detects the hydraulic pressure of the oil discharged from the oil pump, and a control device, The control device a process of determining that the amount of oil stored in the oil pan is reduced when the oil pressure detected by the oil pressure sensor is equal to or lower than a predetermined determination oil pressure; and acquiring a parameter related to the viscosity of the oil during engine operation, and setting the judgment oil pressure based on the acquired parameter. Oil amount determination device.

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