Hydraulic sensor anomaly diagnostic device

Abstract

To accurately diagnose abnormalities in hydraulic sensors, such as seizing. [Solution] The engine 10 includes an oil pump 11, a main gallery 16, and a hydraulic pressure sensor 20. The electronic control unit 21 has a processing circuit 22. The processing circuit 22 performs a first determination process, a second determination process, and a diagnostic process. In the first determination process, it is determined whether the fluctuation amplitude of the output of the hydraulic pressure sensor 20 remains small when the operating state of the oil pump 11 is a stable operating state with a low rate of change in hydraulic pressure. In the second determination process, it is determined whether the amount of change in the output of the hydraulic pressure sensor 20 has decreased when the operating state of the oil pump 11 is a transient operating state with a high rate of change in hydraulic pressure. In the diagnostic process, if the first determination process determines that the fluctuation amplitude remains small, and the second determination process determines that the amount of change in the output has decreased, it is diagnosed that an abnormality has occurred in the hydraulic pressure sensor 20.

Description

Technical Field

[0001] The present invention relates to an abnormality diagnosis device for a hydraulic sensor.

Background Art

[0002] Some engines for vehicles and the like include an oil pump for supplying engine oil to lubrication parts and the like. And, in an engine equipped with an oil pump, there is one in which a hydraulic sensor is installed in an oil passage through which the engine oil discharged by the oil pump flows.

[0003] A failure called a sticking abnormality may occur in the hydraulic sensor, in which the output hardly changes. In the oil passage during engine operation, hydraulic pulsation constantly occurs. And when the above sticking abnormality occurs during engine operation, the hydraulic pressure detected by the hydraulic sensor, specifically, the change amount of the output of the hydraulic sensor becomes small. Patent Document 1 describes that in an engine equipped with a hydraulic variable valve mechanism, when the fluctuation amplitude of the output of the hydraulic sensor remains small and the output indicates a hydraulic pressure exceeding a predetermined low hydraulic pressure determination value, it is determined that the above sticking abnormality has occurred.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, the amplitude of fluctuations in the output of the hydraulic sensor may decrease not only due to the occurrence of the aforementioned seizing abnormality, but also due to variations in hydraulic pulsation that occurs steadily in the oil passage, and electromagnetic noise generated in the electrical circuit including the hydraulic sensor. In this case, there is a risk of mistakenly diagnosing that a seizing abnormality has occurred in the hydraulic sensor even when there is no seizing abnormality. [Means for solving the problem]

[0006] An abnormality diagnosis device for a hydraulic sensor to solve the above problem is applied to an engine comprising an oil pump, an oil passage through which engine oil discharged by the oil pump flows, and a hydraulic sensor for detecting the hydraulic pressure in the oil passage, and is an abnormality diagnosis device for diagnosing whether or not there is an abnormality in the hydraulic sensor, and has a processing circuit, the processing circuit performs: a first determination process for determining whether or not the fluctuation amplitude of the output of the hydraulic sensor remains small when the operating state of the oil pump is a stable operating state with a low rate of change in the hydraulic pressure; a second determination process for determining whether or not the amount of change in the output of the hydraulic sensor has decreased when the operating state of the oil pump is a transient operating state with a high rate of change in the hydraulic pressure; and a diagnosis process for diagnosing that an abnormality has occurred in the hydraulic sensor when the first determination process determines that the fluctuation amplitude remains small and the second determination process determines that the amount of change in the output has decreased. [Effects of the Invention]

[0007] According to the present invention, it is possible to accurately diagnose abnormalities in hydraulic sensors, such as seizing. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram showing the configuration of one embodiment of a hydraulic sensor anomaly diagnosis device. [Figure 2] Figure 2 is a flowchart of the abnormality diagnosis process performed by the abnormality diagnosis device. [Figure 3] Figure 3 is a flowchart of the abnormality diagnosis process. [Figure 4] Figure 4 is a timing chart showing an example of how the abnormality diagnosis process is executed. [Modes for carrying out the invention]

[0009] Below, one embodiment of a hydraulic sensor abnormality diagnosis device will be described in detail with reference to Figures 1 to 4. (Configuration of the oil circulation system of engine 10) First, with reference to Figure 1, the configuration of the oil circulation system of the engine 10 will be explained. The oil circulation system of the engine 10 is equipped with an oil pump 11, an oil strainer 14, an oil filter 15, and a hydraulic pressure sensor 20. The oil pump 11 draws in engine oil from the oil pan 13 of the engine 10 and discharges it. The oil strainer 14 is a filter that filters out relatively large foreign matter contained in the engine oil drawn in by the oil pump 11. The oil filter 15 is a filter that filters out fine foreign matter contained in the engine oil discharged by the oil pump 11. After passing through the oil filter 15, the engine oil discharged by the oil pump 11 is sent to the main gallery 16. Engine oil is distributed and supplied from the main gallery 16 to each lubrication part 17 of the engine 10. The hydraulic pressure sensor 20 is a sensor that detects the hydraulic pressure PO of the main gallery 16. In this embodiment, the main gallery 16 corresponds to the oil passage through which the engine oil discharged by the oil pump 11 flows.

[0010] In this engine 10, a mechanical pump that operates in response to the rotation of the crankshaft 12, i.e., the rotation of the engine 10, is used as the oil pump 11. Furthermore, in the engine 10, a variable displacement pump capable of controlling the amount of oil discharged is used as the oil pump 11.

[0011] (Configuration of the control system for engine 10) Next, with reference to Figure 1, the configuration of the control system for the engine 10 will be described. The engine 10 is controlled by an electronic control unit 21. The electronic control unit 21 includes a processing circuit 22. The processing circuit 22 includes an arithmetic processing unit that executes various processes according to a program, and a memory device that stores various programs and data. The engine 10 is equipped with various sensors that detect state variables indicating the operating state of the engine 10. The sensors include the hydraulic pressure sensor 20 mentioned above. In addition to the hydraulic pressure PO detected by the hydraulic pressure sensor 20, the state variables also include the crank angle, which is the rotational phase of the crankshaft 12 as the output shaft of the engine 10. The electronic control unit 21 receives detection signals for these state variables from the engine 10. Based on the input detection signals, the electronic control unit 21 performs engine control. The electronic control unit 21 also determines the rotational speed of the crankshaft 12 (hereinafter referred to as engine speed NE) and the engine load KL from the state variables for which the detection signals have been input.

[0012] The engine control performed by the electronic control unit 21 includes controlling the discharge volume of the oil pump 11. The electronic control unit 21 calculates the target oil pressure TP, which is the control target value of the oil pressure PO, according to the engine speed NE, engine load KL, etc. The electronic control unit 21 then adjusts the discharge volume of engine oil from the oil pump 11 to match the detected value RP of oil pressure PO by the oil pressure sensor 20 with the target oil pressure TP. This minimizes the power loss of the engine 10 related to driving the oil pump 11, while still being able to supply the amount of engine oil necessary to prevent seizing, etc.

[0013] (Abnormal diagnosis of hydraulic sensor 20) The electronic control unit 21 performs abnormality diagnosis of the hydraulic sensor 20 as part of engine control. In this embodiment, the electronic control unit 21 corresponds to an abnormality diagnosis device for the hydraulic sensor 20. Specifically, the electronic control unit 21 diagnoses whether or not there is a sticking abnormality in the hydraulic sensor 20. A sticking abnormality is a malfunction of the hydraulic sensor 20 in which the output remains at a nearly constant value without changing.

[0014] Figures 2 and 3 show the processing procedure for the abnormality diagnosis process to diagnose whether or not there is a sticking abnormality in the hydraulic sensor 20. This process is executed by the processing circuit 22 of the electronic control unit 21 at predetermined execution cycles. In the following, the step number of each process is represented by a number preceded by "S".

[0015] In this embodiment, the processes S101 to S105 in Figure 2 correspond to a first determination process that determines whether the fluctuation amplitude of the output of the hydraulic sensor 20 remains small when the operating state of the oil pump 11 is a stable operating state with a low rate of change of the hydraulic pressure PO. The processes S201 to S206 in Figure 3 correspond to a second determination process that determines whether the amount of change in the output of the hydraulic sensor 20 has decreased when the operating state of the oil pump 11 is a transient operating state with a high rate of change of the hydraulic pressure PO. The process S207 in Figure 3 corresponds to a diagnostic process that diagnoses that an abnormality has occurred in the hydraulic sensor 20. In the diagnostic process, if the first determination process determines that the fluctuation amplitude remains small, and the second determination process determines that the amount of change in the output of the hydraulic sensor 20 (specifically, the detected value RP) has decreased, then it is diagnosed that an abnormality has occurred in the hydraulic sensor 20.

[0016] (First determination process) As shown in Figure 2, in the first determination process, it is first determined whether or not the preconditions are met (S101). The preconditions are that all of the following requirements (a) to (c) are met. Requirement (a) is that the engine 10 has finished starting. Requirement (b) is that the engine 10 is in an idle state. Requirement (c) is that the engine speed NE is equal to or greater than the predetermined diagnostic lower limit N1.

[0017] If the precondition is not met (S101: NO), this process ends temporarily. On the other hand, if the precondition is met (S101: YES), it is determined whether the following requirement (ii) is met (S102). Requirement (ii) is that the absolute value of the difference between the instantaneous value and the moving average value of the output of the hydraulic sensor 20 is less than or equal to the predetermined sticking determination value J1.

[0018] If it is determined in the process of S102 that requirement (ii) is met (YES), assuming that the fluctuation amplitude is small, it is determined whether the state in which requirement (ii) is met continues for a first predetermined time T1 or more (S103).

[0019] If an affirmative determination is made in the process of S103 (YES), since the state where the fluctuation amplitude of the output of the hydraulic sensor 20 is small continues, it is highly likely that a sticking abnormality has occurred in the hydraulic sensor 20, and the temporary abnormality flag F1 is set to "ON" (S104).

[0020] On the other hand, if a negative determination is made in the process of S103 (NO), although requirement (ii) is met, the duration of the established state is less than the first predetermined time T1, and the first determination process ends temporarily without executing the process of S104.

[0021] On the other hand, if it is determined in the process of S102 that requirement (ii) is not met (NO), since the fluctuation amplitude of the output of the hydraulic sensor 20 is large, it is considered that the possibility of the occurrence of the sticking abnormality is extremely low, and the temporary abnormality flag F1 is set to "OFF" (S105). In this way, after the temporary abnormality flag F1 is set, the first determination process ends temporarily.

[0022] (Second determination process, diagnosis process) In the series of processes shown in Figure 3, it is first determined whether the temporary abnormality flag F1 is set to "ON" (S201). If the result in S201 is negative (NO), the process is terminated without executing the following processes (S202~S208). On the other hand, if the result in S201 is positive (YES), the process in S202 is executed. In this process, the processing circuit 22 executes the following processes (S202~S208) on the condition that the temporary abnormality flag F1 is set to "ON," that is, that a temporary abnormality in the hydraulic sensor 20 has been determined (provisional diagnosis) through the first determination process.

[0023] In the S202 process, it is determined whether the increase in the target hydraulic pressure TP per unit time has reached or exceeded a predetermined judgment value J2. More specifically, in the S202 process, it is determined whether the following requirement (e) is met. Requirement (e) is that the difference ΔTP (=TP[i]-TP[i-1]) between the latest set value TP[i] and the previous set value TP[i-1] for the target hydraulic pressure TP set by the discharge amount control of the oil pump 11 is greater than or equal to the predetermined judgment value J2. The predetermined judgment value J2 is a value that can sufficiently ensure an increase in hydraulic pressure PO when diagnosing the occurrence of a sticking abnormality in the hydraulic pressure sensor 20, and is stored in advance in the memory device of the processing circuit 22.

[0024] If it is determined that requirement (e) is met during the processing of S202 (YES), the value RP detected by the hydraulic pressure sensor 20 at that time is stored in the memory device of the processing circuit 22 as "pre-change hydraulic pressure PO1" (S203). On the other hand, if it is determined that requirement (e) is not met during the processing of S202 (NO), the processing of S203 is not executed.

[0025] Subsequently, it is determined whether both requirements (f) and (g) below are met (S204). Requirement (f) is that immediately after requirement (e) is met, the engine speed NE rises to a predetermined threshold increase J3.

[0026] Requirement (t) is that the elapsed time after requirement (f) has been met is equal to or greater than the second predetermined time T2. Furthermore, the judgment increase amount J3 and the second predetermined time T2 are values ​​that can sufficiently ensure an increase in hydraulic pressure PO when diagnosing the occurrence of a sticking abnormality in the hydraulic pressure sensor 20, and are pre-stored in the memory device of the processing circuit 22. In this embodiment, the operating state of the oil pump 11 in which both requirements (e) and (f) are met corresponds to the transient operating state of the oil pump 11. The transient operating state occurs after the amount of increase of the target hydraulic pressure TP per unit time has become equal to or greater than the predetermined judgment value J2, and immediately after the amount of increase has become equal to or greater than the predetermined judgment value J2, the engine speed NE rises to exceed the predetermined judgment increase amount J3.

[0027] In the S204 process, if the result is negative (NO), it is determined that the increase in engine speed NE is insufficient, or that although the engine speed NE increased, the elapsed time afterward is short, and the process is terminated. In this case, the following processes (S205~S208) are not executed.

[0028] On the other hand, if the S204 process is judged positively (YES), the increase in engine speed NE and the elapsed time are deemed sufficient, and the value RP detected by the hydraulic pressure sensor 20 as the "changed hydraulic pressure PO2" is stored in the memory device of the processing circuit 22 (S205).

[0029] Subsequently, the difference ΔPO (=PO2-PO1) between the changed hydraulic pressure PO2 and the pre-change hydraulic pressure PO1 is calculated, and it is determined whether this difference ΔPO is smaller than a predetermined judgment value J4 (S206).

[0030] Then, if the S206 process is judged positively (YES), the abnormality flag F2 is set to "ON" (S207). In this case, although the output of the hydraulic pressure sensor 20 should change significantly in accordance with the change in the operating state of the oil pump 11, the change in the output is small, so the abnormality flag F2 is set to "ON", and it is confirmed that a sticking abnormality of the hydraulic pressure sensor 20 has occurred (this diagnosis).

[0031] On the other hand, if the S206 process is negative (NO), the abnormality flag F2 is set to "OFF" (S208). In this case, although the output of the hydraulic pressure sensor 20 should change significantly in accordance with the change in the operating state of the oil pump 11, the actual amount of change in the output is large, so the possibility of the above-mentioned sticking abnormality occurring is considered low, and the abnormality flag F2 is set to "OFF". In this case, although the first determination process has made a provisional diagnosis that a sticking abnormality of the hydraulic pressure sensor 20 has occurred, that diagnosis is not confirmed.

[0032] After this abnormal flag F2 is set, the process is terminated. (Effects and workings of the embodiment) Figure 4 shows an example of the execution mode of an abnormality diagnosis process, including the first judgment process, the second judgment process, and the diagnosis process.

[0033] As shown in Figure 4, the processing circuit 22 executes the first determination process (see Figure 2) when the preconditions are met at time t11. In the first determination process, when the oil pump 11 is in a stable operating state, if the fluctuation amplitude of the output of the hydraulic pressure sensor 20 remains small for a first predetermined time T1 or longer, it is tentatively diagnosed that a sticking abnormality of the hydraulic pressure sensor 20 has occurred (time t12). At this time, the tentative abnormality flag F1 is set to "ON".

[0034] When the oil pump 11 is in a stable operating state, the change in hydraulic pressure PO associated with changes in the operating state of the oil pump 11 is small. Therefore, the output of the hydraulic pressure sensor 20 (detected value RP) corresponds to the pulsation of hydraulic pressure PO that occurs steadily in the main gallery 16. In such a stable operating state, the occurrence of a sticking abnormality in the hydraulic pressure sensor 20 can be diagnosed based on the amplitude (more specifically, the amount of change) of the output of the hydraulic pressure sensor 20. In other words, since the output of the hydraulic pressure sensor 20 fluctuates with an amplitude corresponding to the pulsation of hydraulic pressure PO, if this amplitude (more specifically, the amount of change in output) is smaller than expected, or if the output does not change, it can be seen that there is a high possibility that a sticking abnormality in the hydraulic pressure sensor 20 has occurred.

[0035] In this embodiment, when diagnosing an abnormality in the hydraulic sensor 20 during such a stable operating state, a preliminary diagnosis is performed to tentatively determine the occurrence of a seizing abnormality, but a final diagnosis to confirm the occurrence of a seizing abnormality is not performed. This is for the following reasons: The amplitude of fluctuations in the output of the hydraulic sensor 20 may decrease not only due to the occurrence of a seizing abnormality, but also due to variations in hydraulic pulsation that occurs steadily in the main gallery 16, and electromagnetic noise generated in the electrical circuit including the hydraulic sensor 20 and the processing circuit 22. As a result, the amplitude of fluctuations in the output of the hydraulic sensor 20 decreases, which may lead to a false diagnosis that a seizing abnormality has occurred in the hydraulic sensor 20 even when no seizing abnormality has occurred.

[0036] In this embodiment, the processing circuit 22 executes a second determination process and a diagnosis process (see Figure 3) on the condition that a preliminary diagnosis has been performed. In the second determination process, when the oil pump 11 is in a transient operation state (from time t13 onwards), it is determined that a sticking abnormality of the hydraulic pressure sensor 20 has occurred (main diagnosis) because the amount of change in the output of the hydraulic pressure sensor 20 has become small (from time t14 onwards). At this time, the main abnormality flag F2 is set to "ON". Note that, as shown by the dashed line in Figure 4, if the amount of change in the output of the hydraulic pressure sensor 20 becomes large when the oil pump 11 is in a transient operation state (from time t13 onwards), the main diagnosis is not performed (time t14). In this case, the main abnormality flag F2 remains "OFF".

[0037] During the transient operation of the oil pump 11, the hydraulic pressure PO changes significantly in accordance with the changes in the operating state of the oil pump 11. Therefore, the influence of electromagnetic noise and the variation in hydraulic pressure pulsation on the change in the output of the hydraulic pressure sensor 20 is small. Consequently, during the transient operation of the oil pump 11, the influence of electromagnetic noise and the variation in hydraulic pressure pulsation on the diagnosis of sticking abnormalities based on the change in the output of the hydraulic pressure sensor 20 is small.

[0038] According to this embodiment, when such a transient operating state occurs, the occurrence of a sticking abnormality in the hydraulic pressure sensor 20 can be diagnosed based on the amount of change in the output of the hydraulic pressure sensor 20 (specifically, the difference ΔPO). In other words, while the output of the hydraulic pressure sensor 20 should change significantly in accordance with the change in the operating state of the oil pump 11, if the change in the output is small or does not change at all, it can be seen that there is a high possibility that a sticking abnormality in the hydraulic pressure sensor 20 has occurred.

[0039] As described above, according to this embodiment, a preliminary diagnosis of a sticking abnormality in the hydraulic pressure sensor 20 can be made when the oil pump 11 is in a stable operating state. Moreover, even when the oil pump 11 is in a transient operating state, that is, a transient operating state in which the effects of electromagnetic noise and variations in hydraulic pressure pulsation are small, the occurrence of a sticking abnormality in the hydraulic pressure sensor 20 can be confirmed (full diagnosis) by diagnosing the sticking abnormality. Therefore, it is no longer possible to mistakenly diagnose a sticking abnormality in the hydraulic pressure sensor 20 due to the effects of electromagnetic noise or variations in hydraulic pressure pulsation.

[0040] The abnormality diagnosis device of this embodiment described above can achieve the following effects. (1) In this embodiment, the hydraulic sensor 20 is no longer misdiagnosed as having a seizure due to the influence of electromagnetic noise or variations in hydraulic pulsation. Therefore, the seizure of the hydraulic sensor 20 can be diagnosed with high accuracy.

[0041] (2) In this embodiment, a mechanical and variable displacement oil pump 11 is used. The stable operating state of the oil pump 11 is set to a state in which both the rate of change of the engine speed NE per unit time and the rate of change of the target oil pressure TP are low. This allows the first determination process to be executed when the oil pressure PO is in a stable operating state with a low rate of change. Furthermore, the transient operating state of the oil pump 11 is set to a state after the rate of change of the target oil pressure TP has become high, and the rate of change of the engine speed NE is high. This allows the second determination process to be executed under conditions in which a sufficient increase in oil pressure PO is ensured, provided that no sticking abnormality occurs in the oil pressure sensor 20.

[0042] (3) In this embodiment, the state in which the oil pump 11 is in a stable operating state is defined as the state in which the engine 10 is in an idle operating state. This allows the first determination process to be executed when the rate of change of hydraulic pressure PO is very low. Furthermore, the state in a transient operating state is defined as the state after the amount of increase of the target hydraulic pressure TP per unit time has become equal to or greater than a predetermined determination value J2, and immediately after the amount of increase has become equal to or greater than the predetermined determination value J2, the engine speed NE rises to a predetermined determination increase amount J3. This allows the second determination process to be executed when a sufficient amount of increase in hydraulic pressure PO is ensured, provided that no sticking abnormality occurs in the hydraulic pressure sensor 20.

[0043] (4) In this embodiment, the second determination process is executed on the condition that the fluctuation amplitude remains small in the first determination process, or more specifically, that the temporary abnormality flag F1 is set to "ON". According to this embodiment, when the engine 10 is in an idle state, the first determination process is executed under the condition that the oil pump 11 is in a stable operation state, and it is possible to provisionally determine (preliminary diagnosis) that a sticking abnormality of the hydraulic pressure sensor 20 has occurred. Then, immediately after that, when the engine speed NE increases, the second determination process is executed under the condition that the oil pump 11 is in a transient operation state, and the above provisional diagnosis can be confirmed (final diagnosis). According to this embodiment, the diagnosis of a sticking abnormality of the hydraulic pressure sensor 20 can be efficiently performed in accordance with the series of steps in which the operating state of the engine 10 transitions from an idle state to an acceleration state.

[0044] (Example of change) The above embodiment can be implemented with the following modifications. The above embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0045] • Based on the prerequisites, requirement (c) may be omitted. The stable operating state may be defined as any operating state of the engine 10 other than the idle operating state. In short, the stable operating state should be defined as the operating state of the oil pump 11 where the rate of change of hydraulic pressure PO is low.

[0046] The oil pump 11 is not limited to a variable displacement type; a pump of a type in which the relationship between engine speed NE and engine oil discharge volume cannot be changed may also be used. In this configuration, a stable operating state can be defined as when the rate of change of the rotational speed of the oil pump 11, or the rate of change of the engine speed NE, is below a predetermined judgment value. In addition, in the above configuration, a transient operating state can be defined as when the rate of change of the rotational speed of the oil pump 11, or the rate of change of the engine speed NE, is higher than a predetermined judgment value.

[0047] • An electric pump may be used as the oil pump 11. In this configuration, it is advisable to adopt the requirement (c) that the driving power of the oil pump 11 is above a certain value as a prerequisite. Furthermore, in the above configuration, the oil pump 11 can be considered to be in a stable operating state when the rate of change of the target hydraulic pressure TP per unit time remains below a predetermined judgment value for a predetermined period of time or longer. In addition, in the above configuration, the transient operating state can be considered to be when the rate of change of the target hydraulic pressure TP per unit time becomes greater than a predetermined judgment value, and the period immediately following that.

[0048] • The process in S201 of Figure 3 may be omitted. In this case, the first determination process when the system is in a stable operating state and the second determination process when the system is in a transient operating state can be performed at any time, regardless of whether they are performed before or after each other. Then, if the first determination process determines that the fluctuation amplitude remains small, and the second determination process determines that the change in the output of the hydraulic sensor 20 has decreased, then it should be diagnosed that a sticking abnormality of the hydraulic sensor 20 has occurred. [Explanation of Symbols]

[0049] 10… Engine 11… Oil pump 12... Crankshaft 13… Oil pan 14… Oil strainer 15… Oil filter 16…Main Gallery 17… Lubrication part 20… Hydraulic sensor 21…Electronic control unit 22… Processing circuit

Claims

1. An abnormality diagnosis device applied to an engine comprising an oil pump, an oil passage through which engine oil discharged by the oil pump flows, and a hydraulic pressure sensor for detecting the hydraulic pressure in the oil passage, for diagnosing whether or not there is an abnormality in the hydraulic pressure sensor, It has a processing circuit, The aforementioned processing circuit is A first determination process determines whether the fluctuation amplitude of the output of the hydraulic pressure sensor remains small when the operating state of the oil pump is a stable operating state with a low rate of change in hydraulic pressure, A second determination process to determine whether the amount of change in the output of the hydraulic pressure sensor is small when the operating state of the oil pump is a transient operating state with a high rate of change in hydraulic pressure, If the first determination process determines that the fluctuation amplitude remains small, and the second determination process determines that the amount of change has decreased, then a diagnostic process is executed to diagnose that an abnormality has occurred in the hydraulic sensor. A diagnostic device for detecting abnormalities in hydraulic sensors.

2. The oil pump is a mechanical pump that operates in response to the rotation of the engine's output shaft, and is a variable displacement pump capable of controlling the amount of engine oil discharged. The stable operating state is a state in which both the rate of change of the rotational speed of the output shaft and the rate of change of the target hydraulic pressure in the discharge volume control of the oil pump are low. The transient operating state is a state that occurs after the rate of change of the target hydraulic pressure has increased, and is also a state in which the rate of change of the rotational speed of the output shaft is high. An abnormality diagnosis device for a hydraulic sensor according to claim 1.

3. When the engine is in the stable operating state, it is in the idle operating state. The transient operating state is defined as the period after the rate of increase of the target hydraulic pressure per unit time has exceeded a predetermined judgment value, and immediately after the rate of increase exceeds the predetermined judgment value, the rotational speed of the output shaft rises to an amount exceeding the predetermined judgment increase. An abnormality diagnosis device for a hydraulic sensor according to claim 2.

4. The second determination process is executed on the condition that the first determination process determines that the fluctuation amplitude remains small. An abnormality diagnosis device for a hydraulic sensor according to any one of claims 1 to 3.

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