Oil level detector

Abstract

To improve determination accuracy of oil amount lowering.SOLUTION: An oil amount detection device includes: a strainer 15 for sucking an oil stored in an oil pan 24; an oil pump 30 where the oil is introduced via the strainer 15; a hydraulic sensor 51 for detecting a hydraulic pressure discharged from the oil pump 30; and a control device 100. The control device 100 executes: processing for counting duration time in which a hydraulic pressure detected by the hydraulic sensor 51 is below a predetermined determination value; and processing for detecting lowering of an oil amount stored in the oil pan 24 in the case where the duration time is within the value in the predetermined range.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an oil level detecting device. [Background technology]

[0002] For example, the oil level detection device described in Patent Document 1 counts the duration for which the oil pressure of the oil discharged from the oil pump is below a predetermined judgment value, causing a drop in oil pressure, and if the duration is equal to or greater than the predetermined judgment value, it detects that the amount of oil stored in the oil pan is low. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-92177 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the drop in oil pressure continues even if a hardware failure occurs in the oil pump, etc. Therefore, the device described in Patent Document 1 may erroneously detect such a hardware failure as a drop in oil level, and it is therefore desirable to improve the accuracy of determining whether or not the oil level is low. [Means for solving the problem]

[0005] The oil level detection device that solves the above problem is applied to an oil level detection device that has a strainer that draws oil stored in an oil pan, an oil pump into which 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 a process of counting the duration during which the hydraulic pressure detected by the hydraulic pressure sensor is below a predetermined judgment value, and a process of detecting a decrease in the amount of oil stored in the oil pan when the duration is within a specified range.

[0006] According to this configuration, the duration during which the oil pressure of the oil discharged from the oil pump is below a predetermined threshold is counted. Here, if a hardware failure, such as the oil pump, occurs, the drop in oil pressure continues without recovery, and the duration tends to be longer. On the other hand, when the oil level is low, the oil pressure temporarily drops but then recovers, so the duration does not become longer and stays within a predetermined range. Therefore, this configuration detects that the amount of oil stored in the oil pan is low when the duration is within a predetermined range. This makes it possible to correctly distinguish whether the drop in oil pressure is due to a hardware failure or a low oil level, thereby improving the accuracy of determining low oil level. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of an internal combustion engine to which an oil amount detection device is applied; [Figure 2] 4 is a flowchart showing a procedure of a process executed by the control device of the embodiment. [Figure 3] 4 is a timing chart showing the operation of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of an internal combustion engine to which an oil amount detection device is applied will be described with reference to the drawings. <Configuration of the internal combustion engine and oil supply system> First, the configuration of the internal combustion engine and the oil supply system will be described. Note that this configuration is as described in, for example, JP 2021-92177 A, and an outline thereof will be described below.

[0009] 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.

[0010] An oil pan 24 is fixed to the lower end surface of the cylinder block 22 of the internal combustion engine 10, sandwiching the crankshaft 12. Oil for lubricating the internal combustion engine 10 is stored inside the oil pan 24. A strainer 15 for drawing oil is also disposed inside the oil pan 24. An intake port 15a of the strainer 15 faces the bottom surface of the oil pan 24. The end of the strainer 15 opposite the intake port 15a is connected to an oil pump 30 that pumps oil. The oil pump 30 is an internal trochoid variable displacement pump that operates in conjunction with the rotation of the crankshaft 12 of the internal combustion engine 10. An oil flow passage 18 extends from the oil pump 30, connecting to various parts of the internal combustion engine 10 that require lubrication. A hydraulic pressure sensor 51 is disposed midway along the oil flow passage 18, detecting the hydraulic pressure P of the oil discharged from the oil pump 30. An oil temperature sensor 52 for detecting the temperature T of the oil discharged from the oil pump 30 is disposed in the oil flow passage 18 .

[0011] The internal combustion engine 10 is controlled by a control device 100. The control device 100 includes a central processing unit (hereinafter referred to as 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.

[0012] 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 T 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 speed NE, which is the number of rotations 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.

[0013] The control device 100 stores in advance a target oil pressure map for controlling the oil pump 30. The target oil pressure map sets a target value (hereinafter referred to as the target oil pressure PA) of the oil pressure P to be discharged from the oil pump 30 according to the operating state of the internal combustion engine 10. The target oil pressure map sets the target oil pressure PA for each operating region defined by the engine speed NE and the oil temperature T. The amount of oil required at various parts of the internal combustion engine 10 changes according to the engine speed NE. The viscosity of the oil also changes according to the oil temperature T. Therefore, the target oil pressure map sets a target oil pressure PA for each operating region that corresponds to the amount of oil required and the viscosity of the oil for that operating region. The control device 100 determines the target oil pressure PA according to the current engine speed NE and oil temperature T by referring to this target oil pressure map, and controls the oil pump 30 so that the oil pressure P of the oil discharged from the oil pump 30 becomes the target oil pressure PA.

[0014] <About low oil level detection processing> The control device 100 executes an oil level reduction detection process to detect a reduction in the oil level S in the oil pan 24. The reduction in the oil level S corresponds to a reduction in the oil level, which is an indicator of the oil level S. The basic principle of detecting a reduction in the oil level S is as follows. 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 FIG. 1 , if the oil level Q tilts when the oil level S in the oil pan 24 is relatively low, the oil level 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 decreases. Meanwhile, when the inclination of the oil level Q decreases and the entire suction port 15a is submerged in oil again, the intake of air from the suction port 15a ceases, 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 level S is low, the oil pressure P temporarily drops but then recovers. Therefore, the control device 100 utilizes this phenomenon to detect a drop in the oil level S. That is, the control device 100 detects a drop in the oil level S when the duration H during which the oil pressure P is less than the reference oil pressure PZ is within a predetermined range when a corresponding gradient in the oil level Q is expected.

[0015] Fig. 2 shows the procedure for executing the oil level reduction detection process. The process shown in Fig. 2 is realized by the control device 100 repeatedly executing it at predetermined intervals. Note that, below, the step number of each process is represented by a number preceded by "S."

[0016] In the series of processes shown in Fig. 2, the control device 100 first determines a judgment oil pressure PZ and an upper limit acceleration GZ according to the current engine speed NE and oil temperature T (S10). The judgment oil pressure PZ and the upper limit acceleration GZ are set so as to be able to detect that the oil amount S has fallen below a specified oil amount SZ. In this embodiment, the specified oil amount SZ is set to be slightly higher than the lower limit of the appropriate amount of oil amount S while the internal combustion engine 10 is operating. The calculation manner for determining the judgment oil pressure PZ and the upper limit acceleration GZ is as described, for example, in JP 2021-92177 A.

[0017] Next, the control device 100 determines whether the current vehicle acceleration G is less than the upper limit acceleration GZ (S20). If it is determined that the vehicle acceleration G is less than the upper limit acceleration GZ (S20: YES), the control device 100 determines whether the current oil pressure P is less than a predetermined judgment value, that is, a judgment oil pressure PZ (S30).

[0018] If it is determined that the current oil pressure P is less than the judgment oil pressure PZ (S30: YES), the control device 100 determines whether the oil pressure P was determined to be greater than or equal to the judgment oil pressure PZ in the oil pressure determination at S30 the last time this process was executed (S40).

[0019] If the determination in the processing of S40 is affirmative (S40: YES), the control device 100 executes processing to reset the duration time H to "0" (S60). The duration time H is a value indicating the duration during which the hydraulic pressure P has decreased below the determination hydraulic pressure PZ.

[0020] On the other hand, if a negative determination is made in the process of S40 (S40: NO), the control device 100 executes a process of counting the duration H (S50). In the process of S30, if the current oil pressure P is equal to or greater than the determination oil pressure PZ (S30: NO), the control device 100 executes a process of holding the value of the duration time H (S70).

[0021] After executing any one of S50, S60, and S70, the control device 100 next determines whether the current duration H is within a predetermined range (S80). The predetermined range is a range of possible values ​​for the duration of a temporary drop in oil pressure due to a low oil level, with the first threshold value Href1 as the minimum value and the second threshold value Href2 as the maximum value. The first threshold value Href1 may be, for example, the following value: For example, due to a vehicle momentarily bouncing due to an uneven road surface, the oil level Q in the oil pan 24 may jump up or down, momentarily reducing the amount of oil suctioned by the strainer 15 and causing a drop in oil pressure P. The first threshold value Href1 is a value determined as a time period during which a drop in oil pressure P due to a low oil level can be detected, separate from such momentary drops in oil pressure P. The second threshold value Href2 is preset to a maximum possible value for the duration of a temporary drop in oil pressure due to a low oil level.

[0022] If it is determined that the duration H is within a predetermined range (S80: YES), the control device 100 executes processing to update the drop counter K (S90). The drop counter K is a value that is incremented by a predetermined value (for example, "1") when a positive determination is made in S80 for the first time during a trip, and its initial value is "0." Therefore, the value of this drop counter K indicates the number of trips in which a positive determination was made in S80, i.e., the number of trips in which a drop in oil pressure was detected.

[0023] Next, the control device 100 determines whether the updated decrease counter K is equal to or greater than the threshold value Kref (S100). The threshold value Kref is a predetermined value that can determine whether an oil pressure decrease has occurred in multiple trips and therefore a decrease in the oil amount has occurred.

[0024] Then, when it is determined that the updated decrease counter K is equal to or greater than the threshold value Kref (S100: YES), the control device 100 detects a decrease in the oil amount S and turns on the warning light 81 (S110).

[0025] When the process of S110 is completed or when a negative determination is made in each of the processes of S20, S80, and S100, the series of processes shown in FIG. 2 is temporarily terminated. <effect> The operation of the oil level reduction detection process is shown in Figure 3. In the state shown in Figure 3, the vehicle acceleration G is less than the upper acceleration limit GZ. Furthermore, a positive determination has not yet been made in S80 before time t1 in the current trip.

[0026] At time t1, when the oil pressure P, which had been equal to or greater than the threshold oil pressure PZ, falls below the threshold oil pressure PZ, the duration H is reset. If the oil pressure subsequently drops and the state of "oil pressure P<threshold oil pressure PZ" continues, the duration H count continues. Then, at time t2, the oil pressure recovers and the oil pressure P, which had been less than the threshold oil pressure PZ, rises to or above the threshold oil pressure PZ. As a result, the duration H is held, and from time t2 onwards, the value of the duration H is maintained at the value at time t2. If the value of the duration H is less than the first threshold value Href1 at time t2, the decrease counter K is not updated.

[0027] At time t3, when the hydraulic pressure P becomes less than the judgment hydraulic pressure PZ again, the duration H is reset. If the state of "hydraulic pressure P<judgment hydraulic pressure PZ" continues due to a drop in hydraulic pressure, the duration H count continues. Then, at time t4, when the hydraulic pressure P, which had been less than the judgment hydraulic pressure PZ until then, becomes equal to or greater than the judgment hydraulic pressure PZ due to a recovery of the hydraulic pressure, the duration H is held, and from time t4 onwards, the value of the duration H is maintained at the value at time t4. Then, if the value of the duration H is within the range of not less than the first threshold value Href1 and not more than the second threshold value Href2 at time t4, the decrease counter K is updated.

[0028] In the current and subsequent trips, if the value of the decrease counter K becomes equal to or greater than the threshold value Kref, the warning light 81 is turned on. <Effects> The effects of this embodiment will be described.

[0029] (1) In this embodiment, the duration H during which the oil pressure P of the oil discharged from the oil pump 30 is lower than a predetermined threshold oil pressure PZ is counted. Here, if a hardware failure occurs in the oil pump 30 or the like, the drop in oil pressure continues without recovery, and the duration H tends to be long. On the other hand, when the oil level is low, the oil pressure temporarily drops but then recovers. Therefore, the duration H does not become long and remains within a specified range. Therefore, in this configuration, if the duration H is within a specified range, it is detected that the amount of oil stored in the oil pan 24 is low. This makes it possible to correctly determine whether the drop in oil pressure is due to a low oil level rather than a hardware failure, thereby improving the accuracy of determining whether the oil level is low.

[0030] (2) When the value of the drop counter K becomes equal to or greater than the threshold value Kref, it is determined that a drop in oil pressure due to a drop in oil level has occurred, and the warning light 81 is turned on. In other words, if a drop in oil pressure due to a drop in oil level has occurred in multiple trips, it is determined that a drop in oil pressure due to a drop in oil level has occurred. Therefore, when a positive determination is made in the processing of S80 shown in FIG. 2, it is possible to prevent a sudden drop in oil pressure from being erroneously detected as a drop in oil pressure due to a drop in oil level, compared to when the processing of S110 is immediately executed.

[0031] <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.

[0032] The determination of the upper limit acceleration GZ in the process of S10 shown in FIG. 2 and the process of S20 may both be omitted. The processes of S90 and S100 shown in Fig. 2 may be omitted. If the determination in S80 is affirmative, the process of S110 may be executed.

[0033] If the duration H exceeds the second threshold value Href2, a process may be added to determine that a hardware failure has occurred in the oil pump 30 or the like. · The oil pump may be a fixed displacement pump, an electric pump, or a pump other than an inscribed trochoid pump.

[0034] The overall configuration of the internal combustion engine 10 can be modified as needed. For example, the oil pump 30 may be disposed outside the oil pan 24. The oil level detection device is intended for internal combustion engines, but it may also be used for other devices or equipment that need to detect a decrease in the amount of stored liquid. [Explanation of symbols]

[0035] 10...internal combustion engine, 12...crankshaft, 15...strainer, 15a...intake port, 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, 110...central processing unit, 120...memory, 500...vehicle

Claims

[Claim 1] The present invention is applied to an oil level detection device having a strainer that sucks oil stored in an oil pan, an oil pump into which 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 counting a duration during which the oil pressure detected by the oil pressure sensor is less than a predetermined judgment value; a process for detecting a decrease in the amount of oil stored in the oil pan when the duration is within a specified range; and executing a process of determining that a hardware failure has occurred in the oil pump if the duration exceeds the maximum value of the specified range. Oil level detection device.

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