 |
Claims  |
|
|
What is claimed is:
1. A motor drive control system failure monitoring apparatus designed to monitor a failure in operation of a motor drive control system which controls rotation of a motor
working to output torque to a motor-driven member through a torque transmitting mechanism and an output shaft joined to the motor-driven member and includes a motor angular position sensor working to produce an output as a function of an angular position
of the motor for use in controlling rotation of the motor to bring the angular position of the motor into agreement with a target one and an output shaft angular position sensor working to produce an output as a function of an angular position of the
output shaft, said failure monitoring apparatus comprising: a first comparing circuit working to compare one of the output of the motor angular position sensor and a change in the output of the motor angular position sensor with one of the output of the
output shaft angular position sensor and a change in the output of the output shaft angular position sensor; a second comparing circuit working when the motor is at rest to compare the output of the motor angular position sensor with the target angular
position when the motor is at rest; and a failure diagnosing circuit working to discriminate among failures in operation of the motor angular position sensor and the output shaft angular position sensor and another type of failure using results of the
comparisons as made by said first and second comparing circuits; wherein when the result of comparison made by said first comparing circuit shows that the one of the output of the motor angular position sensor and the change in the output of the motor
angular position sensor mismatches the one of the output of the output shaft angular position sensor and the change in the output of the output shaft angular position sensor, said failure diagnosing circuit discriminates between the failures in operation
of the motor angular position sensor and the output shaft angular position sensor based on whether the result of comparison made by the second comparing circuit shows a match between the output of the motor angular position sensor and the target angular
position or not, and wherein when the result of comparison made by said first comparing circuit shows that the one of the output of the motor angular position sensor and the change in the output of the motor angular position sensor matches the one of the
output of the output shaft angular position sensor and the change in the output of the output shaft angular position sensor, said failure diagnosing circuit discriminates between the failures in operation of the motor angular position sensor and the
output shaft angular position sensor based on whether the result of comparison made by the second comparing circuit shows a mismatch between the output of the motor angular position sensor and the target angular position or not.
2. A motor drive control system failure monitoring apparatus as set forth in claim 1, wherein when it is determined that the output shaft angular position sensor is failing, said failure diagnosing circuit stores failure information indicating
thereof in a storage device, performs a given warning operation, and controls the motor to bring the angular position thereof into agreement with the target one using the output of the motor angular position sensor in a feedback control mode, wherein
when it is determined that the motor angular position sensor is failing, said failure diagnosing circuit stores failure information indicating thereof in the storage device, performs a given warning operation, and switches control of the motor from the
feedback control mode to open-loop control mode, and wherein when it is determined that the another type of failure is occurring, said failure diagnosing circuit stores failure information indicating thereof in the storage device, performs a given
warning operation, and stops driving the motor.
3. A motor drive control system failure monitoring apparatus designed to monitor a failure in operation of a motor drive control system which controls rotation of a motor working to output torque to a motor-driven member through a torque
transmitting mechanism and an output shaft joined to the motor-driven member and includes a motor angular position sensor working to produce an output as a function of an angular position of the motor for use in controlling rotation of the motor to bring
the angular position of the motor into agreement with a target one and an output shaft angular position sensor working to produce an output as a function of an angular position of the output shaft, said failure monitoring apparatus comprising: a first
comparing circuit working to compare one of the output of the motor angular position sensor and a change in the output of the motor angular position sensor with one of the output of the output shaft angular position sensor and a change in the output of
the output shaft angular position sensor; a second comparing circuit working when the motor is at rest to compare the output of the motor angular position sensor with the target angular position when the motor is at rest; and a failure diagnosing
circuit working to discriminate among failures in operation of the motor angular position sensor and the output shaft angular position sensor and another type of failure using results of the comparisons as made by said first and second comparing
circuits; wherein when it is determined that the output shaft angular position sensor is failing, said failure diagnosing circuit stores failure information indicating thereof in a storage device, performs a given warning operation, and controls the
motor to bring the angular position thereof into agreement with the target one using the output of the motor angular position sensor in a feedback control mode, wherein when it is determined that the motor angular position sensor is failing, said failure
diagnosing circuit stores failure information indicating thereof in the storage device, performs a given warning operation, and switches control of the motor from the feedback control mode to open-loop control mode, and wherein when it is determined that
the another type of failure is occurring, said failure diagnosing circuit stores failure information indicating thereof in the storage device, performs a given warning operation, and stops driving the motor.
4. A motor drive control system failure monitoring apparatus designed to monitor a failure in operation of a motor drive control system which controls rotation of a motor working to output torque to a motor-driven member through a torque
transmitting mechanism and an output shaft joined to the motor-driven member and includes a motor angular position sensor working to produce an output as a function of an angular position of the motor for use in controlling rotation of the motor to bring
the angular position of the motor into agreement with a target one and an output shaft angular position sensor working to produce an output as a function of an angular position of the output shaft, said failure monitoring apparatus comprising: a first
comparing circuit working to compare one of the output of the motor angular position sensor and a change in the output of the motor angular position sensor with one of the output of the output shaft angular position sensor and a change in the output of
the output shaft angular position sensor; a second comparing circuit working when the motor is at rest to compare the output of the motor angular position sensor with the target angular position when the motor is at rest; and a failure diagnosing
circuit working to discriminate among failures in operation of the motor angular position sensor and the output shaft angular position sensor and another type of failure using results of the comparisons as made by said first and second comparing
circuits; wherein the motor-driven member is a range shift mechanism working to shift one of gear ranges of an automotive automatic transmission to a selected one.
5. A method of monitoring and diagnosing failure modes of a motor drive control system which controls rotation of a motor working to output torque to a motor-driven member through a torque transmitting mechanism and an output shaft joined to
the motor-driven member and includes (a) a motor angular position sensor and (b) an output shaft angular position sensor said method comprising: (i) comparing an output of the motor angular position sensor with an output of the output shaft angular
position sensor, (ii) comparing the output of the motor angular position sensor with a target angular position taken when the motor is at rest, and (iii) discriminating among possible failure modes in operation of the motor angular position sensor and
the output shaft angular position sensor and another type of failure using results of said comparisons; wherein when the result of step (i) shows that an output of the motor angular position sensor mismatches an output of the output shaft angular
position sensor step (iii) discriminates between failures in operation of the motor angular position sensor and the output shaft angular position sensor based on whether the result of step (ii) shows a match between the output of the motor angular
position sensor and a target angular position or not, and when the result of step (i) shows that an output of the motor angular position sensor matches an output of the output shaft angular position sensor step (iii) discriminates between failures in
operation of the motor angular position sensor and the output shaft angular position sensor based on whether the result of step (ii) shows a mismatch between the output of the motor angular position sensor and a target angular position or not.
6. A method as in claim 5 wherein: when it is determined that the output shaft angular position sensor is failing, failure information to that effect is stored, a warning signal is generated and the motor to controlled to bring its angular
position into agreement with a target position using an output of the motor angular position sensor in a feedback control mode, when it is determined that the motor angular position sensor is failing, failure information to that effect is stored, a
warning signal is generated and control of the motor is switched from a feedback control mode to an open-loop control mode, and when it is determined that another type of failure is occurring, failure information to that effect is stored, warning signal
generated and the motor is stopped.
7. A method of monitoring and diagnosing failure modes of a motor drive control system which controls rotation of a motor working to output torque to a motor-driven member through a torque transmitting mechanism and an output shaft joined to
the motor-driven member and includes (a) a motor angular position sensor and (b) an output shaft angular position sensor said method comprising: (i) comparing an output of the motor angular position sensor with an output of the output shaft angular
position sensor, (ii) comparing the output of the motor angular position sensor with a target angular position when the motor is at rest, and (iii) discriminating among possible failure modes in operation of the motor angular position sensor and the
output shaft angular position sensor and another type of failure using results of said comparisons; wherein when it is determined that the output shaft angular position sensor is failing, failure information to that effect is stored warning signal is
generated and the motor is controlled to bring its angular position into agreement with a target position using the output of the motor angular position sensor in a feedback control mode, when it is determined that the motor angular position sensor is
failing, failure information to that effect is stored, warning signal is generated and control of the motor is switched from a feedback control mode to open-loop control mode, and when it is determined that another type of failure is occurring, failure
information to that effect is stored, a warning signal is generated and the motor is stopped.
8. A method of monitoring and diagnosing failure modes of a motor drive control system which controls rotation of a motor working to output torque to a motor-driven member through a torque transmitting mechanism and an output shaft joined to
the motor-driven member and includes (a) a motor angular position sensor and (b) an output shaft angular position sensor said method comprising: (i) comparing an output of the motor angular position sensor with an output of the output shaft angular
position sensor. (ii) comparing the output of the motor angular position sensor with a target angular position when the motor is at rest, and (iii) discriminating among possible failure modes in operation of the motor angular position sensor and the
output shaft angular position sensor and another type of failure using results of said comparisons; wherein the motor-driven member is a range shift mechanism working to shift one of gear ranges of an automotive transmission to a selected one. |
|
 |
|
 |
Claims |
|
|
|
Description |
|
|
CROSS REFERENCE TO RELATED DOCUMENT
The present application claims the benefit of Japanese Patent Application No. 2003-425925 filed on Dec. 22, 2003, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates generally to a failure monitor for a motor drive control system which controls rotation of a motor working to output torque to a motor-driven member through a torque transmitting mechanism and an output shaft joined
to the motor-driven member.
2. Background Art
In recent years, in order to meet space saving requirements, facilitating ease of assembly, or improving controllability of automotive vehicles, there have been increased trends toward use of an electrical system working to drive a controlled
mechanism through an electric motor. For example, Japanese Patent First Publication No. 2002-323127 discloses an automatic transmission control system designed to actuate a range shift mechanism for automotive automatic transmissions using an electric
motor. A selection of gear ranges of the automatic transmission is achieved by actuating the range shift mechanism using a drive shaft joined to an output shaft of the motor through a speed reducing mechanism. The motor has installed thereon an encoder
working to measure an angular position of the output shaft of the motor. The system uses an output of the encoder to rotate the motor to bring the angular position thereof into agreement with a target one (i.e., a target count value of the encoder),
thereby establishing a selected one of the gear ranges of the automatic transmission through the range shift mechanism.
The rotation of the motor is converted into that of the drive shaft (i.e., a manipulated variable of the range shift mechanism) through the speed reducing mechanism. A speed reducing mechanism of this type is typically made of a gear train in
which there is inevitably some play or looseness between gears. In a case where the speed reducing mechanism is joined to the drive shaft through fitting of a D-shaped connector formed on the tip of an axis thereof into a mating recess formed in the
drive shaft, some clearance is required to facilitate ease of such fitting, which will, however, result in an error in the amount by which the output shaft is rotated by the motor even if the motor is controlled accurately by monitoring the output of the
encoder as representing the angular position of the motor, thus leading to a difficulty in controlling the manipulated variable of the range shift mechanism correctly.
In order to compensate for the error in the amount by which the output shaft is rotated, an output shaft angular position sensor may also be used to measure the angular position of the output shaft for controlling the motor to bring the angular
position of the output shaft into agreement with a target one under feedback control.
However, if an error in the output of the output shaft angular position sensor arises from some failure in operation thereof, it will result in an error in controlling the manipulated variable of the, range shift mechanism. This may cause the
automatic transmission to be shifted to an erroneous one of the gear ranges through the range shift mechanism or disenable the range shift mechanism to change the gear of the automatic transmission and result in a difficulty in monitoring a malfunction
of the feedback control system.
If the encoder working to measure the angular position of the motor has failed, it will result in a difficulty in rotating the motor to the target angular position (i.e., the target count value of the encoder). This may cause the automatic
transmission to be shifted to an erroneous one of the gear ranges through the range shift mechanism or disenable the range shift mechanism to change the gear of the automatic transmission.
If the output shaft angular position sensor and the encoder are operating normally, but the rotary system has undergone an excessive increase in rotational resistance therein or a mechanical lock, it also results in a difficulty in rotating the
motor correctly, thus causing the range shift mechanism to be shifted to an incorrect gear range or disenabled.
SUMMARY OF THE INVENTION
It is therefore a principal object of the invention to avoid the disadvantages of the prior art.
It is another object of the invention to provide a failure monitor designed to discriminate among failures in operation of a motor angular position sensor and an output shaft angular position sensor, as used in a motor drive control system of the
type as described above, and another type of failure.
According to one aspect of the invention, there is provided a motor drive control system failure monitoring apparatus designed to monitor a failure in operation of a motor drive control system. The motor drive control system works to control
rotation of a motor working to output torque to a motor-driven member through a torque transmitting mechanism and an output shaft joined to the motor-driven member and includes a motor angular position sensor working to produce an output as a function of
an angular position of the motor for use in controlling rotation of the motor to bring the angular position of the motor into agreement with a target one and an output shaft angular position sensor working to produce an output as a function of an angular
position of the output shaft. The motor drive control system failure monitoring apparatus comprises: (a) a first comparing circuit working to compare one of the output of the motor angular position sensor and a change in the output of the motor angular
position sensor with one of the output of the output shaft angular position sensor and a change in the output of the output shaft angular position sensor; (b) a second comparing circuit working to compare the output of the motor angular position sensor
with the target angular position when the motor is at rest; and (c) a failure diagnosing circuit working to discriminate among failures in operation of the motor angular position sensor and the output shaft angular position sensor and another type of
failure using results of the comparisons as made by the first and second comparing circuits.
Specifically, the first comparing circuit may be designed to determine whether the one of the output of the motor angular position sensor and the change thereof matches the one of the output of the output shaft angular position sensor and the
change thereof within a permissible range which includes an error arising from the play of the torque transmission mechanism or not. If they mismatch each other, there is a possibility that either one of the motor angular position sensor and the output
shaft angular position sensor is failing.
The second comparing circuit may be designed to determine whether the output of the motor angular position sensor matches the target angular position when the motor is at rest or not. If they match each other, there is a possibility that the
motor angular position sensor or the motor itself is disenabled due to a mechanical lock.
Therefore, using a combination of the above determinations, the failure diagnosing circuit may discriminate among the failures in operation of the motor angular position sensor and the output shaft angular position sensor and the another type of
failure.
In the preferred mode of the invention, when the result of comparison made by the first comparing circuit shows that the one of the output of the motor angular position sensor and the change thereof mismatches the one of the output of the output
shaft angular position sensor and the change thereof, the failure diagnosing circuit discriminates between the failures in operation of the motor angular position sensor and the output shaft angular position sensor based on whether the result of
comparison made by the second comparing circuit shows a match between the output of the motor angular position sensor and the target angular position or not. When the result of comparison made by the first comparing circuit shows that the one of the
output of the motor angular position sensor and the change thereof matches the one of the output of the output shaft angular position sensor and the change thereof, the failure diagnosing circuit discriminates between the failures in operation of the
motor angular position sensor and the output shaft angular position sensor based on whether the result of comparison made by the second comparing circuit shows a mismatch between the output of the motor angular position sensor and the target angular
position or not.
When it is determined that the output shaft angular position sensor is failing, the failure diagnosing circuit may store failure information indicating thereof in a storage device, perform a given warning operation, and control the motor to bring
the angular position thereof into agreement with the target one using the output of the motor angular position sensor in a feedback control mode. When it is determined that the motor angular position sensor is failing, the failure diagnosing circuit may
store failure information indicating thereof in the storage device, perform a given warning operation, and switch control of the motor from the feedback control mode to open-loop control mode. When it is determined that the another type of failure is
occurring, the failure diagnosing circuit may store failure information indicating thereof in the storage device, perform a given warning operation, and stop driving the motor.
The motor-driven member may be a range shift mechanism working to shift one of gear ranges of an automotive automatic transmission to a selected one.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be understood more fully from the detailed description given hereinbelow and from the accompanying drawings of the preferred embodiments of the invention, which, however, should not be taken to limit the invention to
the specific embodiments but are for the purpose of explanation and understanding only.
In the drawings:
FIG. 1 is a perspective view which shows a motor drive control system failure monitoring system according to the first embodiment of the invention;
FIG. 2 is a block diagram which shows a circuit structure of the motor drive control system failure, as illustrated in FIG. 1;
FIG. 3 is a flowchart of a program executed by an electronic control unit (ECU) of the motor drive control system failure monitoring system of FIG. 2;
FIG. 4 is a view which shows relations between outputs of switches of an output shaft sensor and angular positions of the output shaft (i.e., gear ranges of automatic transmission) according to the second embodiment of the invention;
FIG. 5 is a schematic view which shows a structure of an output shaft sensor according to the second embodiment of the invention; and
FIG. 6 is a flowchart of a program executed by an electronic control unit (ECU) of the motor drive control system failure monitoring system of FIG. 2 according to the second embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings, wherein like reference numbers refer to like parts in several views, particularly to FIGS. 1, 2, and 3, there is shown a motor drive control system failure monitoring apparatus according to the first embodiment of the
invention which is used, as an example, to monitor a failure in operation of a motor drive system for a range shift mechanism 11 working to change the gear of an automatic transmission 12 for automotive vehicles.
The automatic transmission 12, as referred to therein, has a typical structure which is designed to be switchable in operation between four gear ranges: a parking (P) range, a reverse (R) range, a neutral (N) range, and a drive (D) range. The
range shift mechanism 11 works to shift the P, R, N, and D ranges of the automatic transmission 12 from one to another. The range shift mechanism 11 is driven by an electric motor 13. The motor 13 is made of a synchronous motor such as a switched
reluctance motor (SRM) and has a speed reducing mechanism 14 installed therein, as shown in FIG. 2. The speed reducing mechanism 14 has an output shaft joined to the range shift mechanism 11 through an output shaft 15. The motor 13 also includes an
output shaft sensor 16 which measures an angular position thereof and outputs a signal indicative thereof.
The output shaft 15, as clearly shown in FIG. 1, has secured thereon a detent lever 18 which works to change a valve position of a manual valve 17 disposed in a hydraulic circuit of the automatic transmission 12. The detect lever 18 has jointed
thereto an L-shaped parking rod 19 which has a conical head 20 in abutment with a lock lever 21. The lock lever 21 is shifted vertically, as viewed in the drawing, around a support shaft 22 as the conical head 20 is moved by a shifting motion of the
parking rod 19, thereby locking or unlocking a parking gear 23. The parking gear 23 is joined to an output shaft of the automatic transmission 12. When the parking gear 23 is locked from rotating by the lock lever 21, it will cause driven wheels of the
automotive vehicle to be placed in parking mode.
The detent lever 18 has jointed thereto a spool valve 24 of the manual valve 17 through a pin. When the detent lever 18 is rotated by the motor 13 through the output shaft 15, it shifts the position of the spool valve 24 of the manual valve 17,
thereby changing one of the P, R, N, and D ranges to another. The detent lever 18 has a waved end wall in which four recesses 25 are formed. The recesses 25 serve to hold the spool valve 24 at any one of four positions corresponding to the P, R, N, and
D ranges of the automatic transmission 12, respectively.
A detent spring 26 is firmly fixed on the manual valve 17. The detent spring 26 has affixed to the tip thereof a pin 27 which engages a selected one of the recesses 25 of the detent lever 18 to hold the detent lever 18 at a corresponding one of
four angular positions thereof, thereby holding the spool valve 24 of the manual valve 17 at the position corresponding to a selected or target one of the P, R, N, and D ranges of the automatic transmission 12.
When it is required to establish the P range, the parking rod 19 is moved to the lock lever 21 and then lifts it up at a large-diameter portion of the conical head 20 to bring a protrusion 21 a of the lock lever 21 into engagement with one of
gear teeth of the parking gear 23 so that the parking gear 23 is locked. This causes the output shaft (i.e., a driving shaft) of the automatic transmission 12 to be locked and placed in the parking mode.
Alternatively, when it is required to establish the gear range other than P range, the parking rod 19 is moved away from the lock lever 21 to bring the large-diameter portion of the conical head 20 into disengagement from the protrusion 21a of
the lock lever 21, so that the protrusion 21a leaves one of gear teeth of the parking gear 23. This causes the output shaft of the automatic transmission 12 to be unlocked and allowed to rotate to ensure the running of the vehicle.
The output shaft sensor 16 is implemented by an angular position sensor such as a potentionmeter which works to produce an output voltage as a function of an angular position of the output shaft 15 of the speed reducing mechanism 14 of the motor
13. The output voltage is used to determine to which of the P, R, N, and D ranges the automatic transmission 12 is to be shifted.
The motor 13 has also installed thereon an encoder 31 working as an angular position sensor to measure an angular position of a rotor of the motor 13. The encoder 31 is implemented by, for example, a magnetic rotary encoder which is designed to
output one of A-, B-, and Z-phase pulse signals in synchronization with rotation of the rotor of the motor 13 to a range selection control unit 32. The range selection control unit 32 includes motor drivers 34 and 35, and an electronic control unit
(ECU) 33. The ECU 33, as will be described later in detail, serves as a system failure monitor. The ECU 33 counts both a leading and a trailing edge (also called a rising and a falling edge) of each of the A- and B-phase signals and uses such a count
value (will also be referred to as an encoder count value below) to change among phases of the motor 13 in a scheduled sequence to energize the motor 13 through the motor drivers 34 and 35, thereby achieving rotation of the motor 13.
The ECU 33 samples an input sequence of the A- and B-phase signals to determine a rotational direction of the rotor of the motor 13 and increments the encoder count value when the motor 13 is rotating in a normal direction in which the gear range
of the automatic transmission 12 is shifted from the P to D range or decrements the encoder count value when the motor 13 is rotating in a reverse direction in which the gear range of the automatic transmission 12 is shifted from the D to P range. This
establishes a matching between the encoder count value and the angular position of the motor 13 regardless of the rotational direction of the motor 13. The ECU 33 also samples the encoder count value to determine the angular position of the motor 13 and
energizes a winding of one of the phases of the motor 13 corresponding to the determined angular position to activate the motor 13. Note that the Z-phase signal outputted by the encoder 31 is used in the ECU 33 to detect a reference angular position of
the rotor of the motor 13.
When a vehicle operator has shifted a gear shift lever to one of a parking (P), a reverse (R), a neutral (N), and a drive (D) position which correspond to the P, R, N, and D ranges of the automatic transmission 12, respectively, the ECU 33
determines a target angular position of the motor 13 (i.e., a target value of the encoder count value) and starts to electrically energize or rotate the motor 13 under feedback control until the encoder count value reaches the target one. Additionally,
the ECU 33 samples the output voltage of the output shaft sensor 16 to monitor an instantaneous angular position of the output shaft 15 (i.e., the amount by which the spool valve 24 of the manual valve 17 has been moved) and determine in or to which of
the P, R, N, and D ranges the automatic transmission 12 is placed or being shifted currently, thereby deciding whether a transmission gear change between the P, R, N, and D ranges has been completed correctly or not. The ECU 33 may also work to correct
the target angular position of the motor 13 using the output voltage of the output shaft sensor 16 so as to compensate for a difference or error in angular position between the motor 13 and the outpu | | |
