Method for diagnosing abrasion of electric oil pump rotor

A method for diagnosing abrasion of an electric oil pump rotor includes sensing a driving duty of an oil pump control unit, and determining whether the sensed driving duty of the oil pump control unit is below a set reference value, wherein as a result of the determining, when the driving duty of the oil pump control unit is below the set reference value, it is determined that the electric oil pump rotor is in a worn out state.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of priority to Korean Patent Application No. 10-2015-0094087, filed Jul. 1, 2015 with the Korean Intellectual Property Office, the entire contents of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a method for diagnosing abrasion of an electric oil pump rotor.

BACKGROUND

Recently, interest in hybrid vehicles with improved fuel efficiency has been increasing. Such hybrid vehicles generally have an electric oil pump (hereinafter, referred to as “EOP”) for supplying a working fluid required for actuating a transmission and a clutch which are interposed between an engine and an actuating motor. Further, the hybrid vehicles generally have an oil pump control unit (hereinafter, referred to as “OPU”) for controlling the electric oil pump operation.

The EOP generates hydraulic pressure by rotating a rotor therein using a driving force of a motor and pumping transmission fluid (ATF) to the transmission. However, when the rotor of EOP is abraded, a proper hydraulic pressure is not generated in the transmission such that the performance of the transmission is decreased. In such a case, the pump needs to be replaced.

Generally, according to a prior art, a system where the EOP and a mechanical oil pump (MOP) are coupled has been used. In such a case, the abrasion situation of the electric oil pump rotor can be diagnosed by measuring and noting that the amount of current consumed when the electric oil pump rotor is worn out is lower than the amount of current consumed when the electric oil pump rotor is normal.

However, often the mechanical oil pump is deleted in order to improve fuel efficiency in an automatic transmission of the hybrid vehicles, and a method for supplying oil by optimally controlling a flow rate by means of only the EOP has been adopted. In other words, the mechanical oil pump which is an oil supply module of a general automatic transmission is deleted in the automatic transmission of the hybrid vehicles, the EOP which is actuated when more than 40V of high voltage, is applied in order to supply a sufficient flow rate. As a result, the amount of current consumed by the EOP decreases, and thus there is a problem in that the prior method for diagnosing abrasion of the electric oil pump rotor based on the amount of current becomes inaccurate.

The description provided above described as a related art is just for helping in understanding the background of the present disclosure and should not be construed as being included in the related art known by those skilled in the art.

SUMMARY

It is an object of the present disclosure to provide a method for diagnosing abrasion of an electric oil pump rotor capable of accurately diagnosing the abrasion state of the electric oil pump rotor using a driving duty of an oil pump control unit.

In one aspect, the present disclosure provides a method for diagnosing abrasion of an electric oil pump rotor includes a step of diagnosing the electric oil pump rotor using a driving duty of the oil pump control unit.

The step of diagnosing includes a step of sensing a driving duty of an oil pump control unit; a step of determining whether the sensed driving duty of the oil pump control unit is less than a set reference value; and a step of determining, by the controller, the electric oil pump rotor is in a worn out state, when the sensed driving duty of the oil pump control unit is less than the set reference value.

As a result of the determining step, the method may include a step of outputting a warning signal when the driving duty of the oil pump control unit is below the set reference value.

The method may further include, before the diagnosing step, a step of confirming whether it is possible to perform the diagnosing, wherein as a result of the confirming step, when it is possible to perform the diagnosing, the sensing step is performed.

The confirming step may include determining whether a voltage inputted into the OPU is included in a preset region, and the diagnosing is not performed when the voltage is not included in the preset region.

The confirming step may includes determining whether a temperature of an automatic transmission fluid is below a predetermined temperature, and the diagnosing is not performed when the temperature of the automatic transmission fluid is below the predetermined temperature.

The confirming step may include determining whether a temperature sensor for sensing a temperature of an automatic transmission fluid is operable, and the diagnosing is not performed when the temperature sensor is inoperable.

The confirming step, when may include determining whether the number of revolutions of the EOP is included in a set number of revolution, and the diagnosing is not performed when the number of revolutions of the EOP is not included in the set number of revolutions.

The confirming step may include determining whether other diagnostic counts are generated in the OPU, and the diagnosing is not performed when other diagnostic counts are generated.

The step of determining whether the sensed driving duty of the oil pump control unit is below a set reference value may determine whether the driving duty of the oil pump control unit is less than a set driving duty region, and the outputting step may output a warning signal when the driving duty of the oil pump control unit is less than the set driving duty region.

DETAILED DESCRIPTION

Hereinafter reference will now be made in detail to various embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings and described below. While the disclosure will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the disclosure to those exemplary embodiments. On the contrary, the disclosure is intended to cover the exemplary embodiments as well as various alternatives, modifications, equivalents and other embodiments; which may be included in the spirit and scope of the disclosure as defined by the appended claims.

Hereinafter a method for diagnosing abrasion of an electric oil pump rotor according to the preferred embodiment of the present disclosure is described with reference to drawings attached.

FIG. 1is a flow chart illustrating a method for diagnosing abrasion of an electric oil pump rotor according to an embodiment of the present disclosure,FIG. 2is a graph illustrating ratios of a number of a revolution of the EOP to the driving duty of the oil pump control unit value according to an embodiment of the present disclosure, andFIG. 3is a block diagram illustrating an apparatus of diagnosing abrasion of an electric oil pump rotor according to an embodiment of the present disclosure. Referring toFIGS. 1 to 3, a method for diagnosing abrasion of an electric oil pump rotor may include sensing a driving duty of an oil pump control unit1S110; and determining whether the sensed driving duty of the oil pump control unit is less than a preset reference value S120, wherein as a result of the determining, when the driving duty of the oil pump control unit is less than the preset reference value, it is determined that the electric oil pump rotor is in a worn out state.

Conventionally, since the mechanical oil pump (hereinafter referred to as “MOP”) and the EOP are provided as a coupled system, sufficient oil pressure may have been supplied to an automatic transmission even though the EOP is actuated with low voltage.

However, since the MOP is removed to improve fuel efficiency and the EOP has to be actuated with high voltage in order to provide flow rate only by the EOP, current consumption becomes relatively very low. As such, as the current consumed for actuating the EOP becomes low, the accuracy of the abrasion diagnosis of the EOP using current value is decreased. Accordingly, the present disclosure describes that the abrasion of the EOP is diagnosed based on the driving duty of the oil pump control unit rather than the amount of current consumed in order to actuate the EOP. The abrasion diagnosis of the electric oil pump rotor based on the driving duty of the oil pump control unit is performed using a transmission control unit (TCU)5or a hybrid control unit (HCU)7which is a high rank controller of the OPU1, or the OPU itself. The TCU5, the HCU7and the OPU1can be referred to as a controller.

The driving duty of the oil pump control unit1may be a control characteristic value which indicates generally an actuating amount and an actuating frequency required for actuating the EOP by the OPU for a predetermined period of time. For example, assuming that the number of revolution required of the EOP3increases, the OPU actuates the EOP3faster or more frequently than before so that the EOP3actuates with the number of faster revolution and thus the driving duty of the oil pump control unit1increases. In contrast, when the number of revolution required of the EOP3decreases, the OPU1actuates less than before and thus the driving duty of the oil pump control unit1decreases. However, this is an example of changes in the driving duty of the oil pump control unit when the EOP3is in a load condition as a normal state in which the electric oil pump rotor is not worn out.

If abrasion of the electric oil pump rotor occurs, the EOP3performs no-load actuation such as an idle actuation since load is not generated and thereby the amount of the current consumed in order to actuate the EOP3becomes a very small value. Since this case is the state where load is not applied to the EOP3, the driving duty of the oil pump control unit of a normal state corresponding to the number of revolutions required to the EOP3may not be formed. The driving duty of the oil pump control unit1in the state where the electric oil pump rotor is worn out is formed smaller than the driving duty of the oil pump control unit1in the normal state.

The present disclosure is capable of diagnosing abrasion of the electric oil pump rotor more precisely than the conventional diagnosis method which uses current consumed by performing the diagnosis of the abrasion of the electric oil pump rotor based on changes in the driving duty of the oil pump control unit1.

Additionally, as a result of the determining S120, when the driving duty of the oil pump control unit is less than the reference value, the method may include outputting a warning signal S130.

The reference value may be set to be the driving duty of the oil pump control unit at the time of determining when the EOP does not smoothly provide oil pressure to the automatic transmission due to abrasion of the electric oil pump rotor, but the specific value may be variable according to a vehicle and a designer.

For example, referring toFIG. 2, when the driving duty of the oil pump control unit1is included in the outputting region of the warning signal that is smaller than the reference value, the EOP3is actuated with a no-load condition, wherein it is determined that abrasion of the engine oil pump rotor has occurred, thereby outputting a warning signal which demands a replacement of the EOP3S130. In contrast, when the driving duty of the oil pump control unit is greater than the reference value, it is determined that abrasion of the electric oil pump rotor has not occurred, thereby normally actuating the EOP3and again being capable of sensing the driving duty of the oil pump control unit1.

The warning signal may be output to a display device or an audio device, thereby allowing a driver or a repair person to recognize a replacement of the electric oil pump rotor.

Meanwhile, the present disclosure further includes before the sensing S110, confirming whether an oil pump control unit diagnosis is possible S100, wherein as a result of the confirming S100, when the oil pump control unit diagnosis is possible, the sensing S110is performed.

According to the present disclosure, it is possible to reduce a phenomenon of increasing repair costs incurred due to misdiagnosis of the abrasion state of the electric oil pump rotor, which is performed by the OPU1, by confirming whether the oil pump control unit diagnosis is possible before the abrasion diagnosis of the electric oil pump rotor is performed using the driving duty of the oil pump control unit1, in the condition where correct diagnosis is possible.

Specifically, the cases where diagnosis of the abrasion state of the electric oil pump rotor through the OPU1is impossible are as follows. First, at the time of confirming S100, when the voltage inputted into the OPU1is not included in the preset region, it may determine that the oil pump control unit diagnosis is impossible and terminates the control. In this case, the preset region may be any voltage region within which it is determined that the abrasion of the electric oil pump rotor is clearly diagnosed using the driving duty of the oil pump control unit by stably supplying the voltage inputted into the OPU1. When the voltage inputted into OPU1is less than the preset region, since the driving duty of the oil pump control unit1measured is small, the abrasion diagnosis of the electric oil pump rotor based on the driving duty of the oil pump control unit1may not be accurate.

Accordingly, in case of hybrid vehicles, when the voltage inputted into the OPU1is within the region from more than 230V to less than 300V, it is determined that the abrasion diagnosis of the electric oil pump rotor is accurate and thereby the driving duty of the oil pump control unit1may be sensed. In addition, in the case of plug-in hybrid vehicles, when the voltage inputted into the OPU1is within the region from more than 320 V to less than 390V, it is determined that the abrasion diagnosis of the EOP3is accurate and thereby the driving duty of the oil pump control unit may be sensed. However, this is only a set voltage regions as an embodiment and may be set to be varied according to the vehicle and the designer.

Further, at the time of confirming S100, when the temperature of an automatic transmission fluid (ATF) is less than a predetermined temperature, or when a temperature sensor for sensing the temperature of the automatic transmission fluid is broken, it is determined that the oil pump control unit diagnosis is unable to terminate the control.

This is intended to perform the abrasion diagnosis of the electric oil pump rotor, only when the automatic transmission fluid pumped into the automatic transmission continues to maintain a predetermined temperature or more. In other words, in a case such as winter, the temperature of the automatic transmission fluid may become less than 0° C. and in this case the abrasion diagnosis of the electric oil pump rotor based on the driving duty of the oil pump control unit1is not accurate, and thus the abrasion diagnosis logic is not performed. Further, when the temperature sensor is broken, the temperature of the automatic transmission fluid may not be grasped and accordingly the reliability of the driving duty of the oil pump control unit1is reduced, and thus the abrasion diagnosis logic is not performed.

Further, at the time of confirming S100, when the number of revolutions of the EOP3is not included in a set region thereof, it is determined that the oil pump control unit diagnosis is unable to terminate the control. This is to perform the rotor abrasion diagnosis after confirming that the EOP3is actuated with the number of the revolutions through which it may be determined that EOP3is actually actuated. For example when the number of the revolution of the EOP3is less than the set region thereof, it is determined that the EOP3is not actuated so as not to diagnose the abrasion state of the electric oil pump rotor which is not actuated, thereby preventing energy consumption due to unnecessary control.

Finally, at the time of confirming S100, when other diagnostic count occurs in the OPU1, it is determined that the oil pump control unit diagnosis is unable to terminate the control. In other words, when other control logic is being performed by the OPU1, since the driving duty of the oil pump control unit1may be uncertainly sensed, the abrasion state of electric oil pump rotor may not be diagnosed.

Only when satisfying the abrasion diagnosis condition described above, the abrasion diagnosis of the electric oil pump rotor is performed, thereby preventing losses by misdiagnosis.

Meanwhile, according to the present disclosure, it is determined whether the driving duty of the oil pump control unit is less than a set driving duty region in the determining step S120, and when the driving duty of the oil pump control unit is less than the set driving duty region, the warning signal is output in the outputting step S130.

Referring toFIG. 2, when the driving duty of the oil pump control unit1is included in a normal driving duty region between a maximum driving duty and a minimum driving duty that are each set according to the number of revolutions of the EOP3, the electric oil pump rotor may be diagnosed as a best state. When the electric oil pump rotor is worn out, the driving duty of the oil pump control unit1is less than the normal driving duty region, wherein the present disclosure may designate the region of values obtained by multiplying the normal driving duty region by 0.2 as the set driving duty region. However, this is only a driving duty region set according to an embodiment, and thus may be variably set according to the vehicle and the designer.

According to a method for diagnosing abrasion of an electric oil pump rotor having a structure described above, the abrasion of the electric oil pump rotor actuated by high voltage may be accurately diagnosed by using the driving duty of the oil pump control unit1.

Further, according to the present disclosure, the misdiagnosing of the abrasion condition of the electric oil pump rotor may be prevented by confirming whether the OPU1may perform the abrasion diagnosis before the abrasion condition of the electric oil pump rotor is diagnosed.