METHOD FOR DIAGNOSTIC AN ENGINE LUBRICATION SYSTEM

Abstract

Method for diagnosing a lubrication system (24) of an engine (22), the method comprising: Control of an oil pump (28) with a control signal, wherein the control signal is a command with a value for a desired lubricant pressure from the oil pump (28) for a current operating state of the engine (22); Comparing the value of the control signal for the current operating state of the motor (22) with a limit value for the current operating state of the motor (22) to determine whether the value of the control signal for the current operating state of the motor (22) is essentially equal to the limit value for the current operating state of the motor (22) or whether the value of the control signal for the current operating state of the motor (22) differs from the limit value for the current operating state of the motor (22); and Analyzing the value of the control signal with the processing unit (32) to detect a fault in the lubrication system (24) when the value of the control signal for the current operating state of the engine (22) deviates from the limit value for the current operating state of the engine (22); wherein analyzing the value of the control signal to detect a fault in the lubrication system (24) includes determining whether the value of the control signal is greater than the limit value when the motor (22) is operating at low lubrication fluid pressure, and whether the value of the control signal is less than the limit value when the motor (22) is operating at high lubrication fluid pressure; and wherein analyzing the value of the control signal to detect a fault in the lubrication system (24) further includes determining via the processing unit (32) whether the value of the control signal deviates from the limit value only at low speeds of the motor (22) when the motor (22) operates at high lubricant pressure, whether the value of the control signal is not greater than the limit value when the motor (22) operates at low lubricant pressure, or whether the value of the control signal is not less than the limit value when the motor (22) operates at high lubricant pressure; characterized by the fact that Analyzing the value of the control signal to detect a fault in the lubrication system (24), further including comparing, via the processing unit (32), a remaining percentage of oil life with a lifetime limit value to determine whether the remaining percentage of oil life is greater than the oil lifetime limit value, or whether the remaining percentage of oil life is not greater than the oil lifetime limit value, if the value of the control signal deviates from the limit value only at low engine speeds (22) when the engine (22) is operating at high lubricant pressure; or that Analyzing the value of the control signal to detect a fault in the lubrication system, and furthermore, issuing a message via the processing unit indicating a blockage in the engine's oil channel when the value of the control signal is not less than the limit value at low engine speeds, and when the fault severity is greater than a critical threshold.

Description

INTRODUCTION

[0001] The disclosure generally relates to a method for diagnosing a lubrication system of an engine according to the preamble of claim 1 or claim 2, as is essentially known from JP 2000-328917 A.

[0002] Similar procedures can also be found in the documents DE 10 2013 201 258 A1 and DE 10 2011 111 353 A1.

[0003] Engines include a lubrication system with an oil pump that directs a lubricating fluid, such as oil, through an oil passage in the engine. As used herein, the term "oil passage" includes not only the passages in the engine through which lubricating fluid flows, but also the surfaces between moving parts that are lubricated by the lubricating fluid. Accordingly, the oil passage includes bearing surfaces, piston rings, cylinder bores, passages, etc. The oil pump applies a desired lubricating fluid pressure to the lubricating fluid and directs the lubricating fluid through the oil passage. The desired lubricating fluid pressure can vary for different engine operating conditions and must be maintained during engine operation.

[0004] A vehicle control unit is connected to the oil pump and signals from the oil pump with a control signal. The control signal is a command with a specific value. The control signal controls the oil pump to provide the desired lubricating fluid pressure for the current engine operating conditions. The vehicle control unit controls the oil pump to provide different lubricating fluid pressures for different engine operating conditions by adjusting the value of the control signal.

[0005] Wear in the oil pump and / or oil gallery, such as wear in the oil pump guide vanes or wear between bearing surfaces or between piston rings and the cylinder bores, can affect the fluid pressure in the lubrication system. In addition, a blockage in the oil gallery can affect the fluid pressure in the lubrication system. The vehicle control unit monitors the actual lubricating fluid pressure in the oil gallery and adjusts the value of the control signal to provide the desired lubricating fluid pressure. For example, if the actual lubricating fluid pressure in the oil gallery decreases for a particular engine operating condition, due to excessive wear, for example, the vehicle control unit can adjust the value of the control signal to the oil pump to increase the lubricating fluid pressure and achieve the desired lubricating fluid pressure for that engine operating condition. SUMMARY

[0006] According to the invention, a method for diagnosing a lubrication system of an engine is presented, which is characterized by the features of claim 1 or those of claim 2.

[0007] The method includes controlling an oil pump with a control signal from a vehicle control unit. The control signal is a command with a value for a desired lubricating fluid pressure from the oil pump for a current operating condition of the engine. A processing unit compares the value of the control signal for the current operating condition of the engine with a limit set point for the current operating condition of the engine to determine whether the value of the control signal for the current operating condition of the engine is substantially equal to the limit set point for the current operating condition of the engine or whether the value of the control signal for the current operating condition of the engine deviates from the limit set point for the current operating condition of the engine.If the processing unit detects that the value of the control signal for the current operating state of the engine deviates from the limit control value for the current operating state of the engine, the processing unit evaluates the value of the control signal to detect a fault in the lubrication system.

[0008] In one embodiment of the method, the value of the control signal for the current operating state of the motor is substantially equal to the limit control value for the current operating state of the motor when the value of the control signal is within + / - 15% of the limit control value. The percentage difference can vary. Accordingly, in other embodiments, the value of the control signal for the current operating state of the motor is substantially equal to the limit control value for the current operating state of the motor when the value of the control signal deviates by + / - a predefined percentage based on the specific application.

[0009] In one embodiment of the method, analyzing the value of the control signal to detect a fault in the lubrication system includes tracking at least one operating condition of the engine relative to the value of the control signal. The at least one operating condition of the engine includes at least an engine speed, the desired lubricating fluid pressure from the oil pump, an actual lubricating fluid pressure from the oil pump, and a lubricating fluid temperature.

[0010] In a further aspect of the method, the processing unit may normalize the value of the control signal for the current operating state of the engine based on a current lubricating fluid temperature.

[0011] In another aspect of the method, analyzing the value of the control signal to determine a fault in the lubrication system includes whether the value of the control signal is greater than the limit control value when the motor is operating at low lubricating fluid pressure and whether the value of the control signal is less than the limit control value when the motor is operating at high lubricating fluid pressure. If the processing unit determines that the value of the control signal is greater than the limit control value when the motor is operating at low lubricating fluid pressure and that the value of the control signal is less than the limit control value when the motor is operating at high lubricating fluid pressure, the processing unit may calculate a fault severity level. If the fault severity level is greater than a critical threshold, the processing unit may output a message indicating excessive play in the control chamber of the oil pump.

[0012] In another aspect of the method, if the processing unit determines that the value of the control signal is not greater than the limit control value when the motor is operating at low lubricating fluid pressure, or the value of the control signal is not less than the limit control value when the motor is operating at high lubricating fluid pressure, the processing unit determines whether the value of the control signal deviates from the limit control value only at low engine speeds when the motor is operating at high lubricating fluid pressure. If the processing unit determines that the value of the control signal does not deviate from the limit control value only at low engine speeds when the motor is operating at high lubricating fluid pressure, the processing unit outputs a message indicating an unknown error in the lubrication system.

[0013] In another aspect of the method, if the processing unit determines that the value of the control signal deviates from the limit setpoint only at low engine speeds when the engine is operating at high lubricating fluid pressure, the processing unit compares a remaining percentage of oil life with an oil life limit to determine whether the remaining percentage of oil life is greater than the oil life limit or whether the remaining percentage of oil life is not greater than the oil life limit. If the processing unit determines that the remaining percentage of oil life is not greater than the oil life limit, the processing unit outputs a message recommending an oil change.

[0014] In another aspect of the method, if the processing unit determines that the remaining percentage of oil life is greater than the oil life threshold, then the processing unit may calculate a fault severity level. If the processing unit additionally determines that the remaining percentage of oil life is greater than the oil life threshold, then the processing unit determines whether the value of the control signal is less than the low-speed limit setting value. If the processing unit determines that the value of the control signal is not less than the low-speed limit setting value and if the fault severity level is greater than a critical threshold, the processing unit issues a message indicating a blockage in the engine oil passage.If the processing unit detects that the value of the control signal is less than the limit control value at low engine speeds and if the error severity is greater than a critical threshold, the processing unit issues a message indicating excessive play in the engine oil gallery or on the oil pump guide vanes.

[0015] A vehicle is also described. The vehicle includes an engine with an oil passage and a lubrication system with an oil pump that directs a lubricating fluid through the engine's oil passage. A processing unit in communication with the oil pump. The processing unit is operable to diagnose the oil pump. The processing unit includes a processor and a memory with a lubrication system diagnostic algorithm stored therein. The processor is operable to execute the lubrication system diagnostic algorithm to carry out the method for diagnosing the lubrication system of the engine described above.

[0016] The engine lubrication system diagnostic method is a new, unique technique that analyzes the change in the value of the control signal used to control the oil pump under different engine operating conditions to detect various lubrication system faults. This new lubrication system diagnostic method allows the processing unit to detect specific lubrication system components that may require service, thereby improving the processing unit's diagnostic performance.

[0017] The foregoing features and advantages, as well as other features and advantages of the present teachings, will be readily apparent from the following detailed description of the best modes for carrying out the teachings when considered in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic side view of a vehicle. Fig. Figure 2 is a flowchart illustrating a method for diagnosing a lubrication system of an engine. DETAILED DESCRIPTION

[0018] In the FIGS., in which the components are shown numbered in several views, 20 are in Fig. 1 generally refers to the vehicle. The vehicle 20 may include any movable platform, such as a car, a truck, a train, an off-road vehicle, a boat, an airplane, etc.

[0019] With reference to Fig. 1, the vehicle 20 includes an engine 22. The engine 22 may include a type and / or configuration of the engine 22 that includes a lubrication system 24. Unless otherwise described herein, the specific type, construction, operation, and form of the engine 22 are not relevant to the teachings of this disclosure and therefore are not described in detail herein.

[0020] As in Fig. 1, the engine 22 includes an oil passage 26. As used herein, the term "oil passage" includes passageways and lubricated surfaces supplied with a lubricating fluid, such as engine oil, via the passageways. The lubricated surfaces may include bearings and bearing surfaces, piston rings and cylinder bores, etc. The engine 22 includes an oil pump 28 operable to pressurize and circulate a lubricating fluid, such as engine oil, through the oil passage 26. The oil pump 28 draws the lubricating fluid from an oil pan 30 and directs it through the oil passage 26. The lubricating fluid is returned to the oil pan 30 to complete the fluid circulation. The oil pump 28 is actively controlled by a vehicle control module to provide a desired lubricating fluid pressure. As such, the oil pump 28 may be referred to as a continuously variable displacement pump.The oil pump 28 may include a device capable of generating pressure and circulating the lubricating fluid, and is actively controlled by a control signal to provide a desired fluid pressure. The vehicle control unit sends the electronic control signal to the oil pump 28 to adjust the lubricating fluid pressure. Accordingly, the control signal indicates a variable or adjustable value.

[0021] As in Fig. 1, the engine 22 may include a pressure sensor 34 operable to detect a lubricating fluid pressure in the oil passage 26. The pressure sensor 34 is arranged in communication with a processing unit 32 to transmit data regarding the fluid pressure of the lubricating fluid in the oil passage 26 to the processing unit 32. The engine 22 may further include a temperature sensor 36 operable to detect a temperature of the lubricating fluid. The temperature sensor 36 is also in communication with the processing unit 32 to transmit data to the processing unit 32 regarding the temperature of the lubricating fluid.

[0022] The processing unit 32 may generally be referred to as a computer, control unit, control module, and may more specifically be referred to as an engine control unit, engine control module, engine control unit, diagnostic control unit, diagnostic control module, vehicle control unit, etc. The processing unit 32 is operable to perform diagnostics of the engine 22 operation, including the lubrication system 24. In some embodiments, the processing unit 32 may be located onboard the vehicle 20 and integrated with a vehicle control unit for controlling the engine 22. In other embodiments, the processing unit 32 may be located remotely from the vehicle 20, and the required data is transmitted wirelessly from the vehicle 20 to the processing unit 32. The processing unit 32 may include a computer and / or processor 38, as well as software, hardware, memory, algorithms, connections, sensors, etc.necessary for controlling and operating the engine 22, including the lubrication system 24. As such, a method described below and generally in . Fig. 2, may be a program or algorithm operable within processing unit 32. It should be noted that processing unit 32 may include any device capable of analyzing data from various sensors, comparing data, making the necessary decisions required to control engine operation 22 and lubrication system 24, and performing the necessary tasks to control the operation of engine 22 and lubrication system 24.

[0023] The processing unit 32 may be embodied by one or more digital or host computers, each having one or more processors 38, read-only memory (ROM), random access memory (RAM), electrically programmable read-only memory (EPROM), optical drives, magnetic drives, etc., a high-speed clock, analog / digital (A / D) circuits, digital / analog (D / A) circuits, and all necessary input / output (I / O) circuits, input / output devices and communication interfaces, as well as signal conditioning and buffer circuits.

[0024] Computer-readable storage may include a non-volatile / physical medium involved in providing data or computer-readable instructions. Storage may be non-volatile or volatile. Non-volatile media may include, for example, optical or magnetic disks and other persistent storage. Volatile media may include, for example, dynamic random access memory (DRAM) that forms main memory. Other examples of memory embodiments include a floppy disk, a floppy disk, or a hard disk, magnetic tape and / or other magnetic media, a CD-ROM, DVD, or other optical media, as well as other possible storage elements, such as flash memory.

[0025] The processing unit 32 includes a tangible, non-volatile memory 40 storing computer-executable instructions, including a lubrication system diagnostic algorithm 42. The processor 38 of the processing unit 32 is operable to execute the lubrication system diagnostic algorithm 42. The lubrication system diagnostic algorithm 42 implements a method for diagnosing the lubrication system 24 of the engine 22, as described below.

[0026] A vehicle control unit, including processing unit 32, controls oil pump 28 based on the value of the control signal to provide a desired lubricating fluid pressure for a current set of operating conditions of engine 22. Processing unit 32 receives inputs from pressure sensor 34 and temperature sensor 36 regarding the actual lubricating fluid pressure in oil passage 26 and the temperature of the lubricating fluid generated by oil pump 28 for that value of the control signal. The vehicle control unit, such as processing unit 32, can adjust the value of the control signal to achieve the desired lubricating fluid pressure for the current operating conditions of engine 22. For various reasons, for certain operating conditions of engine 22, the actual lubricating fluid pressure in oil passage 26 generated by oil pump 28 may change over time.Accordingly, by tracking the change in the value of the control signal for specific operating conditions of the engine 22, the processing unit 32 can identify if and when a change in the lubrication system 24 affects the lubricating fluid pressure. By evaluating the value of the control signal under different operating conditions, the processing unit 32 can isolate or identify specific components of the lubrication system 24 that may be responsible for the change in the lubricating fluid pressure and that require service or attention.

[0027] As mentioned above, the method of the processing unit 32 executes the lubrication system diagnostic algorithm 42 to implement the diagnostic method of the lubrication system 24 of the engine 22. Referring to Fig. 2, the method for diagnosing the lubrication system 24 includes defining a value for a control signal for a current operating state of the engine 22. The step of defining the value for the control signal for the current operating state of the engine 22 is generally shown in box 100 in Fig. 2. The control signal is a command, with a value, for the oil pump 28 to operate in a specific manner and provide a desired lubricating fluid pressure in the oil gallery 26. The processing unit 32 receives inputs from various sensors and / or other control modules and defines the value of the control signal based on the desired lubricating fluid pressure for the current operating state of the engine 22. Different operating states of the engine 22 require different lubricating fluid pressures, and therefore, a vehicle control unit defines the current value for the control signal for the oil pump 28 based on the current operating state of the engine 22. As the current operating state of the engine 22 changes, the vehicle control unit changes the value of the control signal for the oil pump 28 to provide a different lubricating fluid pressure.The vehicle control unit sends the control signal to the oil pump 28 to control the oil pump 28 with the control signal.

[0028] The processing unit 32 compares the value of the control signal for the current operating state of the motor 22 with a limit control value for the current operating state of the motor 22. The limit control value for the current operating state of the motor 22 is a defined limit for the value of the control signal that indicates an acceptable value of the control signal for the current operating state of the motor 22. The limit control value can include a minimum or maximum value and can be stored in a table in the memory 40 of the processing unit 32. It should be noted that the value of the control signal for all different operating states of the motor 22 has a respective limit control value for the respective operating state of the motor 22. The processing unit 32 compares the value of the control signal with the limit control value defined for the current operating state of the motor 22.

[0029] The limit control value is defined based on the lubricating fluid having a certain temperature. Since fluid pressure is directly related to temperature, the processing unit 32 normalizes the value of the control signal based on a current lubricating fluid temperature to compare the value of the control signal with the limit control value. The step of normalizing the control signal value is generally described in box 102 in Fig. 2. In other words, the processing unit 32 normalizes, i.e., regulates, the value of the control signal to account for the difference between the actual temperature of the lubricating fluid in the oil channel 26 and the temperature of the lubricating fluid used to define the limit control value. The processing unit 32 can normalize the value of the control signal in a suitable manner.

[0030] As mentioned above, the processing unit 32 compares the value of the control signal for the current operating state of the motor 22 with the limit control value for the current operating state of the motor 22 to determine whether the value of the control signal for the current operating state of the motor 22 is substantially equal to the limit control value for the current operating state of the motor 22 or whether the value of the control signal for the current operating state of the motor 22 deviates from the limit control value for the current operating state of the motor 22. The step of comparing the control signal value with the limit control value is generally described in box 104 in Fig. 2. In some embodiments, the value of the control signal for the current operating state of the motor 22 may be considered substantially equal to the limit setpoint for the current operating state of the motor 22 if the value of the control signal is within + / - 15% of the limit setpoint. In other embodiments, however, the value of the control signal for the current operating state of the motor 22 may be considered different from the limit setpoint for the current operating state of the motor 22 if the value of the control signal is not within + / - 15% of the limit setpoint. The percentage difference may vary.Accordingly, in other embodiments, the value of the control signal from the current operating state of the motor 22 is substantially equal to the limit set point for the current operating state of the motor 22 when the value of the control signal is + / - a predefined percentage based on the particular application, and the value of the control signal from the current operating state of the motor 22 deviates from the limit set point for the current operating state of the motor 22 when the value of the control signal is not within or exceeds + / - the predefined percentage for the particular application.

[0031] If the processing unit 32 determines that the value of the control signal for the current operating condition of the engine 22 is substantially equal to the limit setpoint for the current operating condition of the engine 22, generally indicated at 106, the processing unit 32 takes no further action and begins the process again. However, if the processing unit 32 determines that the value of the control signal for the current operating condition of the engine 22 differs from the limit setpoint for the current operating condition of the engine 22, generally indicated at 108, the processing unit 32 then analyzes the difference between the value of the control signal and the limit setpoint for different operating conditions of the engine 22 to detect a fault in the lubrication system 24.

[0032] To evaluate the value of the control signal to detect a fault in the lubrication system 24, the processing unit 32 may track at least one operating condition of the engine 22 relative to the value of the control signal. The step of tracking an operating condition of the engine 22 is generally depicted in box 110 in Fig. 2. The operating state of the engine 22 includes at least a speed of the engine 22, the desired lubricating fluid pressure from the oil pump 28, an actual lubricating fluid pressure from the oil pump 28, and a lubricating fluid temperature. Additionally, the processing unit 32 can track the operating conditions of the engine 22 for different values ​​of the control signal for other operating states of the engine 22. Accordingly, the processing unit 32 tracks the operating conditions of the engine 22 for the different control signals for the various operating states of the engine 22.

[0033] The processing unit 32 uses the tracked data to analyze the value of the control signal and detect a fault in the lubrication system 24. In doing so, the processing unit 32 determines whether the value of the control signal is greater than the limit setting value for the motor 22 when operating at low lubricating fluid pressure and whether the value of the control signal is less than the limit setting value for the motor 22 when operating at high lubricating fluid pressure. In other words, the processing unit 32 determines whether both conditions are met: whether the value of the control signal is greater than the limit setting value for the motor 22 when operating at low lubricating fluid pressure and whether the value of the control signal is less than the limit setting value for the motor 22 when operating at high lubricating fluid pressure.The step of determining whether the value of the control signal is greater than the limit set point for motor 22 when operating at low lubricating fluid pressure and whether the value of the control signal is less than the limit set point for motor 22 when operating at high lubricating fluid pressure is generally shown in box 112 in . Fig. 2. As mentioned above, the desired lubricating fluid pressure may change for different operating conditions of the engine 22. For some operating conditions, the desired lubricating fluid pressure may be defined as a low lubricating fluid pressure. The low lubricating fluid pressure may vary for different embodiments and depend on a speed of the engine. For example, the low lubricating fluid pressure may be defined with respect to a maximum pressure for a certain speed of the engine 22. For example, the low lubricating fluid pressure may be defined as a maximum pressure at a given speed of the engine divided by three (Max Pressure / 3). For other operating conditions, the desired lubricating fluid pressure may be defined as a high lubricating fluid pressure. The high lubricating fluid pressure may vary for different embodiments and depend on a speed of the engine.For example, the high lubricating fluid pressure can be defined in terms of a maximum pressure for a specific speed of the engine 22. For example, the high lubricating fluid pressure can be defined as a maximum pressure at a given speed of the engine multiplied by two thirds (Max Pressure * 2 / 3).

[0034] If processing unit 32 determines that the value of the control signal is greater than the limit setpoint for motor 22 when operating at low lubricating fluid pressure and that the value of the control signal is less than the limit setpoint for motor 22 when operating at high lubricating fluid pressure, generally indicated in box 114, processing unit 32 calculates a fault severity level. The fault severity level is a measure of the difference between the value of the control signal and the limit setpoint for the current operating condition of motor 22. The fault severity level can be calculated in any suitable manner and expressed as a number or a percentage. For example, the fault severity level can be expressed as a percentage difference between the value of the control signal and the limit setpoint.

[0035] If the processing unit 32 determines that the error severity is greater than a critical threshold and that the value of the control signal is greater than the limit setting value for motor 22 when operating at low lubricating fluid pressure, and that the value of the control signal is less than the limit setting value for motor 22 when operating at high lubricating fluid pressure, then the processing unit 32 outputs a message indicating excessive clearance in the control chamber of the oil pump 28. The step of outputting the message indicating excessive clearance in the control chamber of the oil pump 28 is generally described in box 116 in Fig. 2. The critical threshold is a limit of the permissible change in the difference between the value of the control signal and the limit control value, represented by the fault severity. The critical threshold can be defined as an appropriate value based on the specific components of the lubrication system 24 and engine 22 and can be application-specific. Issuing the message indicating excessive play in the control chamber of the oil pump 28 can include a method capable of conveying a message. For example, issuing the message indicating excessive play in the control chamber of the oil pump 28 can include illuminating an indicator code, triggering a warning signal, recording a diagnostic code bit in the memory 40 of the processing unit 32, contacting a remote third party for maintenance scheduling, etc.

[0036] If processing unit 32 determines that the value of the control signal is not greater than the limit setpoint for motor 22 when operating at low lubricating fluid pressure, or that the value of the control signal is not less than the limit setpoint for motor 22 when operating at high lubricating fluid pressure, which is generally indicated in box 118, then processing unit 32 determines whether the value of the control signal deviates from the limit setpoint only at low speeds of motor 22 when motor 22 is operating at high lubricating fluid pressure. In other words, processing unit 32 determines whether both conditions are met, i.e., whether the value of the control signal deviates from the limit setpoint only at low speeds of motor 22 and motor 22 is operating at high lubricating fluid pressure.The step of determining whether the value of the control signal deviates from the limit setpoint only at low speeds for motor 22 when operating at high lubricating fluid pressure is generally performed in box 120 in . Fig. 2. As mentioned above, the desired lubricating fluid pressure may vary for different operating conditions of the engine 22. For some operating conditions, the desired lubricating fluid pressure may be defined as a low speed of the engine 22. As used herein, the low speed of the engine 22 is defined as a speed of the engine 22 that is less than 1,500 revolutions per minute.

[0037] As described above, the value of the control signal is substantially equal to the limit control value when the control signal is within + / - 15% of the limit control value, and the value of the control signal can be considered to deviate from the limit control value when the value of the control signal is not within the limit control value or exceeds it by + / - 15%.

[0038] If the processing unit 32 determines that the value of the control signal deviates from the limit control value not only at low speeds of the motor 22 when the motor 22 is operating at high lubricating fluid pressure, which is generally indicated in box 122, then the processing unit 32 outputs a message indicating an unknown error in the lubrication system 24. The step of outputting the message indicating an unknown error in the lubrication system 24 is generally indicated in box 124 in Fig. 2. In other words, the processing unit 32 only outputs the message indicating an unknown fault in the lubrication system 24 if the value of the control signal deviates from the limit control value at a time other than when the engine 22 is operating at low speeds, when the engine 22 is operating at high lubricating fluid pressure. Outputting the message indicating excessive play in the control chamber of the oil pump 24 may include a method capable of conveying a message. For example, outputting the message indicating an unknown fault in the lubrication system 24 may include illuminating an indicator code, triggering a warning signal, recording a diagnostic code bit in the memory 40 of the processing unit 32, contacting a remote third party for maintenance scheduling, etc.

[0039] If the processing unit 32 determines that the value of the control signal deviates from the limit setpoint only at low speeds of the engine 22 when the engine 22 is operating at high lubricating fluid pressure, which is generally indicated in box 126, then the processing unit 32 compares a remaining percentage of oil life with an oil life limit value. The step of comparing the remaining percentage of oil life with the oil life limit value is generally indicated in box 128 in Fig. 2. The remaining percentage of oil life can be calculated in a suitable manner and is often easily accessible to the processing unit 32 of other diagnostic programs. The critical threshold is a limit indicating that the lubricating fluid needs to be changed. If the remaining percentage of oil life is greater than the limit, then an oil change is recommended. If the remaining percentage of oil life is less than the limit, then no oil change is recommended.

[0040] The remaining percentage of oil life is compared to the oil life limit to determine whether the remaining percentage of oil life is greater than the oil life limit or whether the remaining percentage of oil life is not greater than the oil life limit. If the processing unit 32 determines that the remaining percentage of oil life is not greater than the oil life limit, generally displayed at 130, then the processing unit 32 outputs a message indicating an oil change recommendation. The step of outputting the message recommending an oil change is generally displayed at box 132 in Fig. 2. Outputting the message indicating a recommended oil change may include a method capable of conveying a message. For example, outputting the message indicating the recommended oil change may include: illuminating an indicator code, activating a warning signal, recording a diagnostic code bit in memory 40 of processing unit 32, contacting a remote third party to schedule maintenance, etc.

[0041] If the processing unit 32 determines that the remaining percentage of oil life is greater than the oil life limit, which is generally indicated in box 134, then the processing unit 32 determines whether the value of the control signal is less than the low speed limit setpoint of the engine 22. The step of determining whether the control signal value is less than the low speed limit setpoint is generally indicated in box 136 in Fig. 2. If the processing unit 32 additionally determines that the remaining percentage of oil life is greater than the oil life limit, the processing unit 32 calculates a fault severity. As discussed above, the fault severity is a measure of the difference between the value of the control signal and the limit setpoint for the current operating state of the engine 22. The fault severity can be calculated in any suitable manner and expressed as a number or a percentage. For example, the fault severity can be expressed as a percentage difference between the value of the control signal and the limit setpoint.

[0042] If the processing unit 32 determines that the value of the control signal is not less than the limit control value at low speeds of the engine 22, which is generally indicated in box 138, and if the error severity is greater than the critical threshold, then the processing unit 32 outputs a message indicating a blockage in the oil passage 26 of the engine 22. The step of outputting the message indicating a blockage in the oil passage 26 is generally indicated in box 140 in Fig. 2. Outputting the message indicating a blockage in the oil passage 26 of the engine 22 may include a method capable of conveying a message. For example, outputting the message indicating a blockage in the oil passage 26 of the engine 22 may indicate: illuminating an indicator code, activating a warning signal, recording a diagnostic code bit in the memory 40 of the processing unit 32, contacting a remote third party to schedule maintenance, etc.

[0043] If the processing unit 32 determines that the value of the control signal is less than the limit control value at low speeds of the engine 22, which is generally indicated in box 142, and if the fault severity is greater than the critical threshold, then the processing unit 32 outputs a message indicating excessive clearance in an oil passage 26 of the engine 22 or at the guide vanes of the oil pump 28. The step of outputting the message indicating excessive clearance in the oil passage 26 or at the pump guide vanes is generally indicated in box 144 in Fig.2. Outputting the message indicating excessive clearance in the oil passage 26 of the engine 22 or at the pump vanes of the oil pump 28 may include a method capable of conveying a message. For example, outputting the message indicating excessive clearance in the oil passage 26 of the engine 22 or at the pump vanes of the oil pump 28 may include: illuminating an indicator code, activating a warning signal, recording a diagnostic code bit in the memory 40 of the processing unit 32, contacting a remote third party to schedule maintenance, etc.

Claims

[1] A method for diagnosing a lubrication system (24) of an engine (22), the method comprising: Controlling an oil pump (28) with a control signal, wherein the control signal is a command with a value for a desired lubricating fluid pressure from the oil pump (28) for a current operating state of the engine (22); Comparing the value of the control signal for the current operating state of the motor (22) with a limit control value for the current operating state of the motor (22) to determine whether the value of the control signal for the current operating state of the motor (22) is substantially equal to the limit control value for the current operating state of the motor (22) or whether the value of the control signal for the current operating state of the motor (22) deviates from the limit control value for the current operating state of the motor (22); and Analyzing the value of the control signal with the processing unit (32) to detect a fault in the lubrication system (24) when the value of the control signal for the current operating state of the engine (22) deviates from the limit control value for the current operating state of the engine (22); wherein analyzing the value of the control signal to detect a fault in the lubrication system (24) includes determining whether the value of the control signal is greater than the limit setpoint when the motor (22) is operating at low lubricating fluid pressure and whether the value of the control signal is less than the limit setpoint when the motor (22) is operating at high lubricating fluid pressure; and wherein analyzing the value of the control signal to detect a fault in the lubrication system (24) further includes determining via the processing unit (32) whether the value of the control signal deviates from the limit setting value only at low speeds of the motor (22) when the motor (22) is operating at high lubricating fluid pressure, whether the value of the control signal is not greater than the limit setting value when the motor (22) is operating at low lubricating fluid pressure, or whether the value of the control signal is not less than the limit setting value when the motor (22) is operating at high lubricating fluid pressure; characterized by , that analyzing the value of the control signal to detect a fault in the lubrication system (24), further including comparing, via the processing unit (32), a remaining percentage of oil life with a life limit to determine whether the remaining percentage of oil life is greater than the oil life limit, or whether the remaining percentage of oil life is not greater than the oil life limit if the value of the control signal deviates from the limit set point only at low speeds of the engine (22) when the engine (22) is operating at high lubricating fluid pressure; or that analyzing the value of the control signal to detect a fault in the lubrication system, further including outputting a message via the processing unit indicating a blockage in the oil channel of the engine if the value of the control signal is not less than the limit control value at low engine speeds and if the fault severity is greater than a critical threshold. [2] A method for diagnosing a lubrication system (24) of an engine (22), the method comprising: Controlling an oil pump (28) with a control signal, wherein the control signal is a command with a value for a desired lubricating fluid pressure from the oil pump (28) for a current operating state of the engine (22); Comparing the value of the control signal for the current operating state of the motor (22) with a limit control value for the current operating state of the motor (22) to determine whether the value of the control signal for the current operating state of the motor (22) is substantially equal to the limit control value for the current operating state of the motor (22) or whether the value of the control signal for the current operating state of the motor (22) deviates from the limit control value for the current operating state of the motor (22); and Analyzing the value of the control signal with the processing unit (32) to detect a fault in the lubrication system (24) when the value of the control signal for the current operating state of the engine (22) deviates from the limit control value for the current operating state of the engine (22); wherein analyzing the value of the control signal to detect a fault in the lubrication system (24) includes determining whether the value of the control signal is greater than the limit set point when the motor (22) is operating at low lubricating fluid pressure and whether the value of the control signal is less than the limit set point when the motor (22) is operating at high lubricating fluid pressure; wherein analyzing the value of the control signal to detect a fault in the lubrication system (24) further includes calculating a fault severity level with the processing unit (32) based on whether the value of the control signal is greater than the limit set point when the motor (22) is operating at low lubricating fluid pressure and whether the value of the control signal is less than the limit set point when the motor (22) is operating at high lubricating fluid pressure; wherein analyzing the value of the control signal to detect a fault in the lubrication system (24) further includes outputting a message with the processing unit (32) indicating excessive play of the control chamber in the oil pump (28) if the fault severity is greater than a critical threshold; and characterized by , that analyzing the value of the control signal to detect a fault in the lubrication system (24), further including determining via the processing unit (32) whether the value of the control signal is less than the limit setpoint at low speeds of the engine (22) when the remaining percentage of oil life is greater than the oil life limit; and that analyzing the value of the control signal to detect a fault in the lubrication system, further including outputting a message with the processing unit indicating excessive play in an oil channel of the engine or in pump guide vanes when the value of the control signal is less than the limit control value at low engine speeds and when the fault severity is greater than the critical threshold.

Images