Patent Application
20190040775
The disclosure generally relates to a method of diagnosing a lubrication system of an engine.
Engines include a lubrication system having an oil pump that circulates a lubrication fluid e.g., oil, through an oil gallery of the engine. As used herein, the term “oil gallery” includes not only the passages in the engine through which the lubrication fluid circulates, but also the surfaces between moving parts for which the lubrication fluid lubricates. Accordingly, the oil gallery includes bearing surfaces, piston rings, cylinder bores, passages, etc. The oil pump pressurizes the lubrication fluid to a desired lubrication fluid pressure, and circulates the lubrication fluid through the oil gallery. The desired lubrication fluid pressure may vary for different operating conditions of the engine, and should be maintained during engine operation.
A vehicle controller is connected to the oil pump, and signals the oil pump with a control signal. The control signal is a command having a value. The control signal controls the oil pump to provide the desired lubrication fluid pressure for the current operating conditions of the engine. The vehicle controller controls the oil pump to provide different lubrication fluid pressures for different operating conditions of the engine by adjusting the value of the control signal.
Wear in the oil pump and/or the oil gallery, such as wear in the vanes of the oil pump, or wear between bearing surfaces or between piston rings and the cylinder bores, may affect the fluid pressure in the lubrication system. Additionally, a blockage in the oil gallery may affect the fluid pressure in the lubrication system. The vehicle controller monitors the actual lubrication fluid pressure in the oil gallery, and adjusts the value of the control signal to provide the desired lubrication fluid pressure. For example, if the actual lubrication fluid pressure in the oil gallery decreases for a specific operating condition of the engine, due to excessive wear for example, the vehicle controller may adjust the value of the control signal to the oil pump to increase the lubrication fluid pressure to achieve the desired lubrication fluid pressure for that operating condition of the engine.
A method of diagnosing a lubrication system of an engine is provided. The method includes controlling an oil pump with a control signal from a vehicle controller. The control signal is a command having a value for a desired lubrication fluid pressure from the oil pump for a current operating state of the engine. a processing unit compares the value of the control signal for the current operating state of the engine to a threshold control value for the current operating state of the engine to determine if the value of the control signal for the current operating state of the engine is substantially equal to the threshold control value for the current operating state of the engine, or if the value of the control signal for the current operating state of the engine deviates from the threshold control value for the current operating state of the engine. When the processing unit determines that the value of the control signal for the current operating state of the engine deviates from the threshold control value for the current operating state of the engine, the processing unit analyzes the value of the control signal to identify a fault in the lubrication system.
In one embodiment of the method, the value of the control signal for the current operating state of the engine is substantially equal to the threshold control value for the current operating state of the engine when the value of the control signal is within +/−15% of the threshold control value. The percentage difference may vary. Accordingly, in other embodiments, the value of the control signal from the current operating state of the engine is substantially equal to the threshold control value for the current operating state of the engine when the value of the control signal is +/− a pre-defined percentage based on the specific application.
In one aspect of the method, analyzing the value of the control signal to identify 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 one of a rotational speed of the engine, the desired lubrication fluid pressure from the oil pump, an actual lubrication fluid pressure from the oil pump, and a lubrication fluid temperature.
In another 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 lubrication fluid temperature.
In another aspect of the method, analyzing the value of the control signal to identify a fault in the lubrication system includes determining if the value of the control signal is greater than the threshold control value with the engine operating in a low lubrication fluid pressure regime and if the value of the control signal is less than the threshold control value with the engine operating in a high lubrication fluid pressure regime. When the processing unit determines that the value of the control signal is greater than the threshold control value with the engine operating in the low lubrication fluid pressure regime and that the value of the control signal is less than the threshold control value with the engine operating in the high lubrication fluid pressure regime, the processing unit may calculate a fault severity. When the fault severity is greater than a severity threshold, the processing unit may issue a notification indicating excessive control chamber clearance in the oil pump.
In another aspect of the method, when the processing unit determines that the value of the control signal is not greater than the threshold control value with the engine operating in the low lubrication fluid pressure regime, or the value of the control signal is not less than the threshold control value with the engine operating in the high lubrication fluid pressure regime, then the processing unit determines if the value of the control signal deviates from the threshold control value only at low rotational speeds of the engine with the engine operating in the high lubrication fluid pressure regime. When the processing unit determines that the value of the control signal does not deviate from the threshold control value only at low rotational speeds of the engine with the engine operating in the high lubrication fluid pressure regime, then the processing unit issues a notification indicating an un-identified fault with the lubrication system.
In another aspect of the method, when the processing unit determines that the value of the control signal deviates from the threshold control value only at low rotational speeds of the engine with the engine operating in the high lubrication fluid pressure regime, then the processing unit compares a remaining oil life percentage to an oil life threshold to determine if the remaining oil life percentage is greater than the oil life threshold, or if the remaining oil life percentage is not greater than the oil life threshold. When the processing unit determines that the remaining oil life percentage is not greater than the oil life threshold, then the processing unit issues a notification indicating an advised oil change.
In another aspect of the method, when the processing unit determines that the remaining oil life percentage is greater than the oil life threshold, then the processing unit may calculate a fault severity. Additionally, when the processing unit determines that the remaining oil life percentage is greater than the oil life threshold, then the processing unit determines if the value of the control signal is less than the threshold control value at low rotational speeds of the engine. When the processing unit determines that the value of the control signal is not less than the threshold control value at low rotational speeds of the engine, and when the fault severity is greater than a severity threshold, the processing unit issues a notification indicating an obstruction in an oil gallery of the engine. When the processing unit determines that the value of the control signal is less than the threshold control value at low rotational speeds of the engine, and when the fault severity is greater than a severity threshold, then the processing unit issues a notification indicating excessive clearance in the oil gallery of the engine or in pump vanes of the oil pump.
A vehicle is also provided. The vehicle includes an engine having an oil gallery and a lubrication system having an oil pump operable to circulate a lubrication fluid through the oil gallery of the engine. A processing unit is 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 having a lubrication system diagnostic algorithm stored therein. The processor is operable to execute the lubrication system diagnostic algorithm to execute the method of diagnosing the lubrication system of the engine described above.
The method of diagnosing the lubrication system of the engine is a new, unique method that analyzes the change in the value of the control signal used to control the oil pump for different operating conditions of the engine to identify different faults in the lubrication system. This new method of diagnosing the lubrication system enables the processing unit to identify specific components of the lubrication system that may need service, thereby improving the diagnostic capabilities of the processing unit.
The above features and advantages and other features and advantages of the present teachings are readily apparent from the following detailed description of the best modes for carrying out the teachings when taken in connection with the accompanying drawings.
Those having ordinary skill in the art will recognize that terms such as “above,” “below,” “upward,” “downward,” “top,” “bottom,” etc., are used descriptively for the figures, and do not represent limitations on the scope of the disclosure, as defined by the appended claims. Furthermore, the teachings may be described herein in terms of functional and/or logical block components and/or various processing steps. It should be realized that such block components may be comprised of a number of hardware, software, and/or firmware components configured to perform the specified functions.
Referring to the FIGS., wherein like numerals indicate like parts throughout the several views, a vehicle is generally shown at 20 in
Referring to
As shown in
As shown in
The processing unit 32 may be referred to generally as a computer, a controller, a control module, and may be referred to more specifically as an engine control unit, an engine control module, an engine controller, a diagnostic controller, a diagnostic control module, a vehicle controller, etc. The processing unit 32 is operable to diagnose the operation of the engine 22, including the lubrication system 24. In some embodiments, the processing unit 32 may be located onboard the vehicle 20 and be integrated with a vehicle controller 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 from the vehicle 20 to the processing unit 32 wirelessly. The processing unit 32 may include a computer and/or processor 38, and include all software, hardware, memory, algorithms, connections, sensors, etc., to manage and control the operation of the engine 22, including the lubrication system 24. As such, a method, described below and generally shown in
The processing unit 32 may be embodied as one or multiple digital computers or host machines 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-to-digital (A/D) circuitry, digital-to-analog (D/A) circuitry, and a required input/output (I/O) circuitry, I/O devices, and communication interfaces, as well as signal conditioning and buffer electronics.
The computer-readable memory may include a non-transitory/tangible medium which participates in providing data or computer-readable instructions. Memory may be non-volatile or volatile. Non-volatile media may include, for example, optical or magnetic disks and other persistent memory. Example volatile media may include dynamic random access memory (DRAM), which may constitute a main memory. Other examples of embodiments for memory include a floppy, flexible disk, or hard disk, magnetic tape or other magnetic medium, a CD-ROM, DVD, and/or a other optical medium, as well as other possible memory devices such as flash memory.
The processing unit 32 includes a tangible non-transitory memory 40 having computer executable instructions recorded thereon, 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 of diagnosing the lubrication system 24 of the engine 22, described below.
A vehicle controller, which may include the processing unit 32, controls the oil pump 28 via the value of the control signal to provide a desired lubrication fluid pressure for a current set of operating conditions of the engine 22. The processing unit 32 receives input from the pressure sensor 34 and the temperature sensor 36 regarding the actual lubrication fluid pressure in the oil gallery 26 and the temperature of the lubrication fluid that the oil pump 28 generated for that value of the control signal. The vehicle controller, such as but not limited to the processing unit 32, may adjust the value of the control signal to achieve the desired lubrication fluid pressure for the current operating conditions of the engine 22. For various different reasons, for specific operating conditions of the engine 22, the actual lubrication fluid pressure in the oil gallery 26 generated by the 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 may identify when a change in the lubrication system 24 is affecting the lubrication fluid pressure. By analyzing the value of the control signal during different operating conditions, the processing unit 32 may isolate or identify specific components of the lubrication system 24 that may be responsible for the change in the lubrication fluid pressure, and that may require service or attention.
As noted above, the process of the processing unit 32 executes the lubrication system diagnostic algorithm 42 to implement the method of diagnosing the lubrication system 24 of the engine 22. Referring to
The processing unit 32 compares the value of the control signal for the current operating state of the engine 22 to a threshold control value for the current operating state of the engine 22. The threshold control value for the current operating state of the engine 22 is a defined limit for the value of the control signal indicating an acceptable value of the control signal for the current operating state of the engine 22. The threshold control value may include a minimum or a maximum value, and may be stored in a table on the memory 40 of the processing unit 32. It should be appreciated that the value of the control signal for each different operating state of the engine 22 will have a respective threshold control value for that respective operating state of the engine 22. The processing unit 32 compares the value of the control signal to the threshold control value defined for the current operating state of the engine 22. The threshold control value is defined based on the lubrication fluid being a specific temperature. Because fluid pressure is directly related to temperature, in order to compare the value of the control signal to the threshold control value, the processing unit 32 normalizes the value of the control signal based on a current lubrication fluid temperature. The step of normalizing the value of the control signal is generally indicated by box 102 in
As noted above, the processing unit 32 compares the value of the control signal for the current operating state of the engine 22 to the threshold control value for the current operating state of the engine 22 in order to determine if the value of the control signal for the current operating state of the engine 22 is substantially equal to the threshold control value for the current operating state of the engine 22, or if the value of the control signal for the current operating state of the engine 22 deviates from the threshold control value for the current operating state of the engine 22. The step of comparing the value of the control signal to the threshold control value is generally indicated by box 104 in
When the processing unit 32 determines that the value of the control signal for the current operating state of the engine 22 is substantially equal to the threshold control value for the current operating state of the engine 22, generally indicated at 106, the processing unit 32 takes no further action and begins the process again. However, when the processing unit 32 determines that the value of the control signal for the current operating state of the engine 22 does deviate from the threshold control value for the current operating state of the engine 22, generally indicated at 108, the processing unit 32 then analyzes the difference between value of the control signal and the control threshold value for different operating conditions of the engine 22 to identify a fault in the lubrication system 24.
In order to analyze the value of the control signal to identify 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 the operating conditions of the engine 22 is generally indicated by box 110 in
The processing unit 32 uses the tracked data to analyze the value of the control signal in order to identify a fault in the lubrication system 24. In doing so, the processing unit 32 determines if the value of the control signal is greater than the threshold control value with the engine 22 operating in a low lubrication fluid pressure regime and if the value of the control signal is less than the threshold control value with the engine 22 operating in a high lubrication fluid pressure regime. In other words, the processing unit 32 determines if both conditions are met, i.e., if the value of the control signal is greater than the threshold control value with the engine 22 operating in the low lubrication fluid pressure regime and the value of the control signal is less than the threshold control value with the engine 22 operating in the high lubrication fluid pressure regime. The step of determining if the value of the control signal is greater than the threshold control value with the engine 22 operating in a low lubrication fluid pressure regime and if the value of the control signal is less than the threshold control value with the engine 22 operating in a high lubrication fluid pressure regime is generally indicated by box 112 in
When the processing unit 32 determines that the value of the control signal is greater than the threshold control value with the engine 22 operating in the low lubrication fluid pressure regime and that the value of the control signal is less than the threshold control value with the engine 22 operating in the high lubrication fluid pressure regime, generally indicated at 114, the processing unit 32 calculates a fault severity. The fault severity is a measure of the difference between the value of the control signal and the control threshold value for the current operating state of the engine 22. The fault severity may be calculated in a suitable manner, and may be expressed as a number or a percentage. For example, the fault severity may be expressed as the percent difference between the value of the control signal and the threshold control value.
When the processing unit 32 determines that the fault severity is greater than a severity threshold, and that the value of the control signal is greater than the threshold control value with the engine 22 operating in the low lubrication fluid pressure regime and that the value of the control signal is less than the threshold control value with the engine 22 operating in the high lubrication fluid pressure regime, then the processing unit 32 issues a notification indicating excessive control chamber clearance in the oil pump 28. The step of issuing the notification indicating excessive control chamber clearance in the oil pump 28 is generally indicated by box 116 in
When the processing unit 32 determines that the value of the control signal is not greater than the threshold control value with the engine 22 operating in the low lubrication fluid pressure regime or that the value of the control signal is not less than the threshold control value with the engine 22 operating in the high lubrication fluid pressure regime, generally indicated at 118, then the processing unit 32 determines if the value of the control signal deviates from the threshold control value only at low rotational speeds of the engine 22 with the engine 22 operating in the high lubrication fluid pressure regime. In other words, the processing unit 32 determines if both conditions are met, i.e., if the value of the control signal deviates from the threshold control value only at low rotational speeds of the engine 22 and the engine 22 is operating in the high lubrication fluid pressure regime. The step of determining if the value of the control signal deviates from the threshold control value only at low rotational speeds with the engine 22 operating in the high lubrication fluid pressure regime is generally indicated by box 120 in
As described above, the value of the control signal is substantially equal to the threshold control value when the control signal is within +/−15% of the threshold control value, and the value of the control signal may be considered to deviate from the threshold control value when the value of the control signal is not within or exceeds +/−15% of the threshold control value.
When the processing unit 32 determines that the value of the control signal does not deviate from the threshold control value only at low rotational speeds of the engine 22 with the engine 22 operating in the high lubrication fluid pressure regime, generally indicated at 122, then the processing unit 32 issues a notification indicating an un-identified fault with the lubrication system 24. The step of issuing the notification indicating the un-identified fault with the lubrication system 24 is generally indicated by box 124 in
When the processing unit 32 determines that the value of the control signal deviates from the threshold control value only at low rotational speeds of the engine 22 with the engine 22 operating in the high lubrication fluid pressure regime, generally indicated at 126, then the processing unit 32 compares a remaining oil life percentage to an oil life threshold. The step of comparing the remaining oil life percentage to the oil life threshold is generally indicated by box 128 in
The remaining oil life percentage is compared to the oil life threshold to determine if the remaining oil life percentage is greater than the oil life threshold, or if the remaining oil life percentage is not greater than the oil life threshold. When the processing unit 32 determines that the remaining oil life percentage is not greater than the oil life threshold, generally indicated at 130, then the processing unit 32 issues a notification indicating an advised oil change. The step of issuing the notification advising an oil change is generally indicated by box 132 in
When the processing unit 32 determines that the remaining oil life percentage is greater than the oil life threshold, generally indicated at 134, then the processing unit 32 determines if the value of the control signal is less than the threshold control value at low rotational speeds of the engine 22. The step of determining if the value of the control signal is less than the threshold control value at low rotational speeds is generally indicated by box 136 in
When the processing unit 32 determines that the value of the control signal is not less than the threshold control value at low rotational speeds of the engine 22, generally indicated at 138, and when the fault severity is greater than the severity threshold, then the processing unit 32 issues a notification indicating an obstruction in an oil gallery 26 of the engine 22. The step of issuing the notification indicating the obstruction in the oil gallery 26 is generally indicated by box 140 in
When the processing unit 32 determines that the value of the control signal is less than the threshold control value at low rotational speeds of the engine 22, generally indicated at 142, and when the fault severity is greater than the severity threshold, then the processing unit 32 issues a notification indicating excessive clearance in an oil gallery 26 of the engine 22 or in vanes of the oil pump 28. The step of issuing the notification indicating excessive clearance in the oil gallery 26 or in the pump vanes is generally indicated by box 144 in
The detailed description and the drawings or figures are supportive and descriptive of the disclosure, but the scope of the disclosure is defined solely by the claims. While some of the best modes and other embodiments for carrying out the claimed teachings have been described in detail, various alternative designs and embodiments exist for practicing the disclosure defined in the appended claims.
