Method and system for diagnosing failure of oil pressure sensor

A method and a system that diagnose failure of an oil pressure sensor that senses or detects an operating oil pressure in a target device (e.g., a hydraulic clutch) using oil pressure. The method includes a controller that is configured to store an ignition off time that an ignition is turned off and detect an ignition on time that the ignition is turned on after the ignition has been turned off. In addition, the controller is configured to calculate an elapsed time from the ignition off time to the ignition on time and determine whether the elapsed time is equal to or greater than a predetermined time. When the elapsed time is equal to or greater than the predetermined time the controller is configured to diagnose oil pressure sensor failure and when the elapsed time is less than the predetermined time, stop diagnosing failure of the oil pressure sensor.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2012-0134728 filed in the Korean Intellectual Property Office on Nov. 26, 2012, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a method and a system that diagnoses failure of an oil pressure sensor that senses or detects an operating oil pressure in a device (e.g., a hydraulic clutch) using oil pressure.

(b) Description of the Related Art

In general, a transmission, a clutch, and the like are apparatuses that use oil pressure or hydraulic pressure, in which an oil pressure sensor that senses or detects the oil pressure is installed. The transmission, the clutch, and the like are typically applied to a hybrid vehicle as well as a general vehicle.

The hybrid vehicle uses a motor as a power source, as well as an engine. In the hybrid vehicle1, as illustrated inFIG. 1, an engine10, a motor20, and a transmission40may be arranged in series. The hybrid vehicle1may include an integrated starter-generator (ISG)70and an engine clutch30. The ISG70starts the engine10or generates electric power by torque of the engine10, and the engine clutch30controls power transmission between the engine10and the motor20. The engine clutch30is an element of the hybrid vehicle that is designed to efficiently combine and use power of the engine10and the motor20.

FIG. 2is a configuration diagram illustrating a typical engine clutch. As illustrated inFIG. 2, the engine clutch30may include a friction material36moving via pressure by a fluid (e.g., oil)34of which a quantity is controlled by operation of an oil pump50(or a solenoid valve), and a return spring32that restores the friction material36to an original state when an operating pressure is not applied to the friction material36. The oil pump50is generally controlled by an applied voltage and/or current. Oil pressure applied to the engine clutch30by the oil pump50may be detected by an oil pressure sensor80.

However, as illustrated inFIG. 3, a difference, that is, an error, may exist between an actual pressure detected by the oil pressure sensor80and an ideal pressure that corresponds to a voltage applied to the oil pump50. In the error illustrated inFIG. 3, an offset error, a gain error, and a linearity error may be included. Since the oil pressure detected by the oil pressure sensor80is used in controlling the engine clutch30, when the error as described exceeds a predetermined value guaranteed by oil pressure sensor manufacturers, the oil pressure sensor80may be determined to have failed.

When the oil pressure sensor has been determined to have failed, a warning lamp may be turned on to inform a driver of the oil pressure sensor failure and replacement necessity thereof. Accordingly, even when a command for supplying oil pressure does not exist, when the oil pressure sensor80detects a pressure that exceeds the guaranteed offset error range set by the oil pressure sensor manufacturers, the oil pressure sensor80may be determined to have failed.

In the related art, to determine whether an oil pressure sensor has failed, diagnosing of the oil pressure sensor is implemented when a command for supplying oil pressure does not exist before an oil pump is operated after an ignition on time. The ignition being on means an electrical state in which a hybrid vehicle may be driven by power of a motor.

However, when an ignition is turned on again before a predetermined time passes after the ignition is turned off, the oil pressure sensor may detect a pressure over the guaranteed offset error range due to the remaining pressure in the engine clutch, and thus the oil pressure sensor may be determined to have failed in the diagnosing process. In other words, when a soaking time defined by a time from an ignition off time to an ignition on time is shorter than the predetermined time, the oil pressure sensor may detect a pressure over the guaranteed offset error range due to the remaining pressure in the engine clutch.

It is generally known that the predetermined time is a maximum of 5 minutes. Accordingly, when the soaking time is 5 minutes or more, the remaining pressure in the engine clutch is eliminated. In the related art, when the soaking time is less than the predetermined time, the oil pressure sensor may detect remaining pressure in an engine clutch, and thus the pressure sensor may be diagnosed to have failed.

SUMMARY

The present invention provides a method and a system that diagnoses failure of an oil pressure sensor and has the advantages of preventing an incorrect diagnosis of oil pressure sensor failure by stopping the diagnosis when an ignition is turned on in a state that pressure remains (e.g., a soaking time is less than a predetermined time) in a target device (e.g., an engine clutch) after the ignition is turned off.

An exemplary embodiment of the present invention provides a method of diagnosing failure of an oil pressure sensor that senses oil pressure in a target device, the method including: storing an ignition off time at which an ignition is turned off; detecting an ignition on time at which the ignition is turned on after the ignition has been turned off; calculating an elapsed time from the ignition off time to the ignition on time; determining whether the elapsed time is equal to or greater than a predetermined time; diagnosing failure of the oil pressure sensor when the elapsed time is equal to or greater than the predetermined time; and stopping the diagnosing failure of the oil pressure sensor when the elapsed time is less than the predetermined time.

The ignition off time may be stored using power of a battery. The predetermined time may be set based on a time until the remaining pressure in the target device is eliminated from after the ignition off time. In addition, the target device may be an engine clutch that controls power transmission between an engine and a motor. The elapsed time may be a time until an oil pump supplying pressure to the engine clutch starts to operate from after the ignition off time.

Another embodiment of the present invention provides a system that diagnoses failure of an oil pressure sensor that senses oil pressure in a target device, the system including: an ignition power unit configured to supply electric power to drive a vehicle; an oil pump configured to supply pressure to the target device; a battery configured to supply ordinary power to the system; and a controller configured to diagnose failure of the oil pressure sensor based on time elapsed from an ignition off time.

Specifically, the controller may be operated by a predetermined program, and the predetermined program may include a series of commands that perform a method including: storing an ignition off time that an ignition is turned off; detecting an ignition on time that the ignition is turned on after the ignition has been turned off; calculating an elapsed time from the ignition off time to the ignition on time; determining whether the elapsed time is equal to or greater than a predetermined time; diagnosing failure of the oil pressure sensor when the elapsed time is equal to or greater than the predetermined time; and stopping the diagnosing failure of the oil pressure sensor when the elapsed time is less than the predetermined time.

The controller may include a plurality of units executed by the controller. The plurality of units may include: an ignition off time storing unit configured to store the time that the ignition is turned off; an ignition on time detecting unit configured to detect the ignition on time that the ignition is turned on after the ignition has been turned off; an elapsed time calculating unit configured to calculate an elapsed time from the ignition off time to the ignition on time; and a failure diagnosis performing unit configured to determine whether the elapsed time is equal to or greater than a predetermined time, and configured to stop the diagnosing failure of the oil pressure sensor when the elapsed time is less than the predetermined time.

As described above, according to the exemplary embodiment of the present invention, it may be possible to prevent an incorrect diagnosis of oil pressure sensor failure by stopping the diagnosis of failure of the oil pressure sensor when an ignition turns on in a state when pressure remains (e.g., a soaking time is less than a predetermined time) in a target device (e.g., an engine clutch) after an ignition off time.

Additionally, according to the exemplary embodiment of the present invention, it may be possible to prevent unwanted service due to an incorrect diagnosis of an oil pressure sensor failure.

Further, according to the exemplary embodiment of the present invention, it may be possible to solve a problem that an engine clutch (e.g., a target device) cannot be controlled due to diagnosing an oil pressure sensor as having failed.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

Further, throughout the specification, like reference numerals refer to like elements.

FIG. 4is an exemplary diagram of a system that diagnoses oil pressure sensor failure according to an exemplary embodiment of the present invention. A system that diagnoses oil pressure sensor failure may diagnose failure of an oil pressure sensor that senses or detects operating pressure in a target device (e.g., an engine clutch) using oil pressure.

The system that diagnoses failure of the oil pressure sensor may include an ignition power unit90configured to supply electric power to drive a vehicle, an oil pump50configured to supply pressure to the target device, a battery60configured to supply normal power to the system, and a controller100configured to diagnose failure of the oil pressure sensor based on time elapsed from an ignition off time.

In the exemplary embodiment of the present invention, the vehicle may be a hybrid vehicle that includes the target device. In addition, the target device may be a device operated by oil pressure, and for example, may be an engine clutch30of the hybrid vehicle. Furthermore, the oil pump50, the oil pressure sensor80, the battery60, and the ignition power unit90may be applied to the typical hybrid vehicle.

The controller100may include one or more processors or microprocessors and/or hardware operated by a program including a series of commands that execute a method of diagnosing failure of an oil pressure sensor according to an exemplary embodiment of the present invention, which will be described below.

In an exemplary embodiment of the present invention, when the controller100is applied to a hybrid vehicle, the controller100may include a hybrid control unit (HCU) configured to control operation of the engine clutch30and overall operation of the hybrid vehicle, and a battery control unit (BCU) configured to manage and control the battery60. In the exemplary method of diagnosing failure of the oil pressure sensor according to an exemplary embodiment of the present invention which will be described below, some processes may be performed by the HCU and other processes may be performed by the BMS.

The controller100may include constituent elements as shown in detail inFIG. 5. The detailed constituent elements shown inFIG. 5may be configured with one or more modules including hardware and software. Referring toFIG. 5, the controller100may include a plurality of units executed by the controller. The plurality of units may include an ignition off time storing unit110configured to store a time that the ignition has been turned off, an ignition on time detecting unit120configured to detect an ignition on time at which the ignition is turned on after the ignition has been turned off, an elapsed time calculating unit130configured to calculate an elapsed time (e.g., a soaking time) from the ignition off time to the ignition on time, and a failure diagnosis performing unit140configured to determine whether the elapsed time is equal to or greater than a predetermined time and configured to stop diagnosing failure of the oil pressure sensor when the elapsed time is less than the predetermined time. The controller100may also include an oil pump operating time detecting unit150configured to detect a point in time when the oil pump50supplying oil pressure to the engine clutch30operates.

The ignition off time storing unit110may include a memory configured to store the time at which the ignition is turned off. The elapsed time calculating unit130may include a timer that counts the elapsed time. The timer may provide a reference time to the ignition off time storing unit110, the ignition on time detecting unit120, and the oil pump operating time detecting unit150.

Hereinafter, a method of diagnosing failure of an oil pressure sensor according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In describing the method of diagnosing failure of the oil pressure sensor according to the exemplary embodiment of the present invention, the target device may be an engine clutch of a hybrid vehicle, but it should be understood that the scope of the present invention is not limited thereto. Other configurations to which oil pressure may be substantially supplied by an oil pump and in which oil pressure may be sensed by an oil pressure sensor may be used in the exemplary embodiment of the present invention.

FIG. 6is an exemplary flowchart of a method of diagnosing failure of an oil pressure sensor according to an exemplary embodiment of the present invention. As illustrated inFIG. 6, when the ignition is turned off, the controller100may be configured to store the ignition off time in the ignition off time storing unit110(S110). Since the controller100is operated by power (B+) of the battery, data of the ignition off time stored in the ignition off time storing unit110may be maintained even after the ignition has been turned off.

Furthermore, after the ignition has been turned off, the ignition on time detecting unit120of the controller100may be configured to detect a point in time when the ignition is turned on (S120). In step S120, when the ignition on time is detected, the elapsed time calculating unit130of the controller100may be configured to calculate an elapsed time from the ignition off time to the ignition on time (S130). In step S130, when the elapsed time is calculated, the failure diagnosis performing unit140of the controller100may be configured to determine whether the elapsed time is equal to or greater than a predetermined time (e.g., 5 minutes) (S140).

The predetermined time may be set based on a time until the remaining pressure in the engine clutch is eliminated from after the ignition off time since the remaining pressure in the engine clutch30may exist before the predetermined time has elapsed, thus, the oil pressure sensor80may be diagnosed as having failed due to the remaining pressure.

In step S140, when the elapsed time is equal to or greater than the predetermined time, the failure diagnosis performing unit140of the controller100may be configured to diagnose failure of the oil pressure sensor80(S150). In addition, when the elapsed time is less than the predetermined time, since the remaining pressure in the engine clutch30may exist as described above, the process of diagnosing failure of the oil pressure sensor may stop (S160).

In another exemplary embodiment of the present invention, the oil pump operating time detecting unit150of the controller100may be configured to detect an operating time of the oil pump50independently of detecting the ignition on time. When the operating time of the oil pump50has been detected, the elapsed time calculating unit130of the controller100may be configured to calculate a time elapsed from after the ignition off time to the operating time of the oil pump50, and the failure diagnosis performing unit140of the controller100may be configured to determine whether the process of diagnosing failure of the oil pressure sensor80proceeds, based on the time. Accordingly, according to the exemplary embodiment of the present invention, it may be possible to diagnose failure of an oil pressure sensor without an error (e.g., with minimal error).

Description of Reference Numerals30:Engine clutch50:Oil pump60:Battery80:Oil pressure sensor90:Ignition power unit100:Failure diagnosis controller110:Ignition off time storing unit120:Ignition on time detecting unit130:Elapsed time calculating unit140:Failure diagnosis performing unit150:Oil pump operating time detecting unit