Motor control device

A motor control device is provided which controls a motor by performing switching between forward rotation and reverse rotation so as to cause an object to be controlled to reciprocate, the motor control device including a lead angle map storage unit configured to store a lead angle map in which a motor rotation speed and a lead angle to be set are associated for each of the forward rotation and the reverse rotation, a target rotation speed-setting unit configured to set a target rotation speed of the motor based on an input signal from outside, a lead angle-setting unit configured to obtain the lead angle associated with the set target rotation speed by referring to the lead angle map and set the lead angle as a lead angle of the motor, and a driving control unit configured to control rotation of the motor so as to achieve the set target rotation speed and the set lead angle.

TECHNICAL FIELD

The present invention relates to a motor control device which controls rotation of a motor that operates a wiper device and the like provided in a vehicle.

Priority is claimed on Japanese Patent Application No. 2011-163082, filed Jul. 26, 2011, the content of which is incorporated herein by reference.

BACKGROUND ART

Vehicles are conventionally provided with a wiper device attached to the windshield to wipe off rain, splashes from a preceding vehicle, etc. in order to provide the driver with an optimum field of vision. The wiper device has a wiper arm whose oscillation is controlled by a wiper-driving device and a wiper blade abutting the windshield is mounted on a tip end of the wiper arm. The wiper arm on which the wiper blade is mounted performs a reciprocating motion, so that wiping of the windshield is performed. A link mechanism changes a rotational motion of a motor to a reciprocating motion and thus the wiper arm performs a wiping operation.

Because the wiper arm is required to perform a reciprocating motion, a more efficient and highly-functional wiper device is obtained in case that the motor generating a driving force for the reciprocating motion performs switching between the forward rotation and the reverse rotation, which makes the link mechanism for causing the reciprocating motion unnecessary, rather than in case that the reciprocating motion is implemented through the link mechanism by rotating the motor in only one direction. Therefore, the number of wiper devices which cause the wiper arm to reciprocate by switching the rotation of the motor between the forward rotation and the reverse rotation has recently increased (for example, see Patent Literature 1).

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

Incidentally, when a brush motor is used, it is possible to rotate the motor in a state in which characteristics are good by optimally setting a lead angle. However, there is a problem in that characteristics are degraded during the reverse rotation if the lead angle is optimally set for the forward rotation in case that the motor rotates with switching between the forward rotation and the reverse rotation so as to cause the wiper arm to reciprocate. In order to avoid this problem, it is necessary to use a position of a brush in a state in which there is no lead angle so that there is no difference in motor characteristics between forward rotation and reverse rotation in the wiper device using the motor which performs the forward and reverse rotation.

However, in the state in which there is no lead angle, there is a problem such as poor efficiency in a high rotation zone, a large amount of electric current needs to flow, and an increase of heat generation.

The present invention has been made in view of such circumstances, and an object of the invention is to provide a motor control device capable of suppressing electric power consumption and heat generation by constantly rotating a motor in a state in which efficiency is good.

Solution to Problem

According to the present invention, a motor control device is provided which controls a motor by performing switching between forward rotation and reverse rotation so as to cause an object to be controlled to reciprocate, the motor control device including a lead angle map storage unit configured to store a lead angle map in which a motor rotation speed and a lead angle to be set are associated for each of the forward rotation and the reverse rotation, a target rotation speed-setting unit configured to set a target rotation speed of the motor based on an input signal from outside, a lead angle-setting unit configured to obtain the lead angle associated with the set target rotation speed by referring to the lead angle map and set the lead angle as a lead angle of the motor, and a driving control unit configured to control rotation of the motor so as to achieve the set target rotation speed and the set lead angle.

According to the present invention, the object to be controlled is a wiper device provided in a vehicle.

Advantageous Effects of Invention

According to the present invention, there is an effect in that it is possible to constantly rotate a motor in a state in which characteristics of the motor are good and suppress electric power consumption and heat generation because a lead angle map in which a motor rotation speed (the number of rotations) and a lead angle to be set are associated is stored for each of forward rotation and reverse rotation and the lead angle corresponding to a newly obtained target rotation speed is also varied according to variation in the target rotation speed.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a motor control device according to an embodiment of the present invention will be described with reference to the drawings.FIG. 1is a block diagram illustrating a configuration of the embodiment. Here, an example of a wiper device provided on a vehicle will be described as an object to be controlled according to rotation of a motor to be controlled by the motor control device. InFIG. 1, reference sign1denotes a wiper arm which wipes a windshield. Reference sign2denotes a brushless motor for causing the wiper arm1to perform a wiping operation, and which is possible to change a lead angle by varying a flowing electric current pattern. The wiper arm1is connected to a rotary shaft of the motor2through a link mechanism, and performs the wiping operation by switching a rotational direction of the rotary shaft between forward rotation and reverse rotation and reciprocating the wiper arm1. Reference sign21denotes an angle sensor which detects and outputs the rotational angle of the rotary shaft of the motor. Here, for simplicity of description, the rotational angle of the rotary shaft of the motor2and an operation angle of the wiper arm1will be described as being consistent. That is, the rotary shaft of the motor2is assumed to reciprocate at the rotational angle between 0 degrees and 150 degrees by performing forward and reverse rotations if the operation angle of the wiper arm1is 0 degrees to 150 degrees. Reference sign3denotes a motor-driving unit which drives the motor2by controlling electric power to be supplied according to a driving command.

Reference sign4denotes a control unit which outputs the driving command to the motor-driving unit3in order to control the rotation of the motor2, and includes a microcomputer. Reference sign41denotes a signal input unit which inputs a signal which is transmitted and received within a vehicle via an in-vehicle local area network (LAN), for example, a controller area network (CAN) or a local interconnect network (LIN). The signal input by the signal input unit41includes a signal representing a state of a wiper switch which issues an instruction to start/stop a wiping operation to the wiper device or a signal representing a speed (a low speed, a high speed, intermittence, or the like) of the wiping operation.

Reference sign42denotes a driving control unit which controls the wiping operation of the wiper arm1by controlling the operation of the motor2based on a signal input in the signal input unit41. Reference sign43denotes a parameter storage unit which associates and stores a pattern of the input signal input in the signal input unit41and parameters for controlling the motor2in advance. Reference sign44denotes a lead angle storage unit which stores lead angle map data defining a relationship between the number of rotations of the motor and the lead angle.

Next, a table structure of the parameter storage unit43illustrated inFIG. 1will be described with reference toFIG. 2.

The input signal pattern is made by performing case analysis on input signals. When the signal to be input is a wiper switch signal, the case analysis is made for each signal value (for example, Lo, Hi, or intermittence). In this case analysis, all of the cases are associated and stored in advance when it is necessary to control an operation of the wiper device according to a signal input to the signal input unit41.

There are three control parameters, namely, a “maximum rotation speed,” an “operation start position,” and an “operation end position.” The “maximum rotation speed” is a maximum value of the rotation speed of the motor2when the wiper arm1operates from a current position or a predetermined position to a target position. Here, the rotation speed is represented by the number of rotations [rpm]. The “operation start position” is a position of the wiper arm1when a predetermined operation is started. Here, it is assumed that the position of the wiper arm1is represented by an angle, a storage position of the wiper arm1is 0 degrees, and a return position of the wiper arm1is 150 degrees in a maximum wiping range. The “operation end position” is a position of the wiper arm1when a predetermined operation ends. For example, when the wiper arm is caused to perform a wiping operation in a maximum wiping range, the “operation start position” is 0 degrees and the “operation end position” is 150 degrees.

Next, the operation of the motor2will be described with reference toFIG. 3.FIG. 3is a diagram illustrating variation in the rotation speed of the motor2when the wiper arm1is operated from the operation start position to the operation end position. When the three control parameters (the maximum rotation speed, the operation start position, and the operation end position) are specified according to an input signal pattern, the driving control unit42first obtains a deceleration start position through an arithmetic operation from the operation start position and the operation end position. Then, the rotation speed is accelerated so that the rotation speed of the motor2is set to the maximum rotation speed at the angle of the deceleration start position.

Subsequently, when the deceleration start position has been reached (a point in time at which the maximum rotation speed has been reached), the rotation speed is decelerated so that the rotation speed is changed to deceleration and the rotation speed at the angle of the operation end position becomes 0. At this time, it is possible to implement the operation of the wiper arm1without a sense of incompatibility by smoothly varying the rotation speed as in a curve illustrated inFIG. 3. The operation of the wiper arm1replaces the operation start position and the operation end position of the operation illustrated inFIG. 3and thus the wiper arm1can reciprocate to perform the wiping operation.

Next, a configuration of the lead angle map which defines the number of rotations of the motor and the lead angle stored in the lead angle map storage unit44illustrated inFIG. 1will be described with reference toFIG. 4.FIG. 4is an explanatory diagram illustrating the configuration of the lead angle map which defines the number of rotations of the motor and the lead angle stored in the lead angle map storage unit44illustrated inFIG. 1. In the lead angle map, a relationship between the number of rotations of the motor (rpm) and a lead angle (deg) is defined in advance, and a positive lead angle is defined to increase when the number of rotations during forward rotation increases. In addition, when the number of rotations during reverse rotation increases (when an absolute number of the negative number of rotations increases), a negative lead angle is defined to increase (an absolute value of a negative lead angle is defined to increase). When the number of rotations of the motor (the positive or negative number of rotations) is defined, it is possible to specify the lead angle to be set.

Next, an operation in which the control unit4illustrated inFIG. 1controls the rotation of the motor2will be described with reference toFIG. 5. First, the signal input unit41reads an input signal, and outputs the read input signal to the driving control unit42(step S1). The driving control unit42specifies a pattern of the input signal output from the signal input unit41, and reads control parameters associated with the input signal pattern consistent with the specified input signal pattern from the parameter storage unit43(step S2). Here, a maximum rotation speed of “65,” an operation start position of “0,” and an operation end position of “150” will be described as the control parameters having been read.

Next, the driving control unit42calculates a deceleration start position from the operation start position of “0” and the operation end position of “150” (step S3). The deceleration start position, for example, is set as a middle point ((0+150)/2=75) between the operation start position and the operation end position. Then, the driving control unit42outputs a command for setting a predetermined initial value as the target rotation speed to the motor-driving unit3(step S4). Thereby, the motor2starts rotation.

Next, the driving control unit42reads an angle value output by the angle sensor21(step S5). The angle value output by the angle sensor21corresponds to a value representing a position of the wiper arm1.

Then, the driving control unit42determines whether the read angle value has reached the deceleration start position (step S6). If the determination result indicates that the deceleration start position has not been reached, the driving control unit42waits for a trigger of the control cycle to be input while determining whether the trigger of the control cycle has been input (steps S7and S8).

Then, at a point in time at which the trigger of the control cycle has been input, the driving control unit42obtains a new target rotation speed (the number of rotations) by adding a predetermined addition amount to the target rotation speed (the number of rotations) of the current time point (step S9). Then, the driving control unit42obtains a lead angle corresponding to the newly obtained number of rotations by referring to the lead angle map stored in the lead angle map storage unit44(step S10). Subsequently, the driving control unit42outputs a command for setting the obtained target rotation speed value and lead angle as a new target rotation speed and lead angle to the motor-driving unit3(step S11). The driving control unit42iterates processing operations of steps S5to S11until the deceleration start position is reached. Thereby, the motor2reaches the deceleration start position while the rotation speed increases from the operation start position, as illustrated inFIG. 3. At this time, because an optimum lead angle corresponding to the number of rotations is set, the motor2can efficiently rotate.

Next, at a point in time at which the deceleration start position has been reached, the driving control unit42reads the angle value output by the angle sensor21(step S12). Then, the driving control unit42determines whether the read angle value has reached the operation end position (step S13). If the determination result indicates that the operation end position has not been reached, the driving control unit42waits for a trigger of the control cycle to be input while determining whether the trigger of the control cycle has been input (steps S14and S15).

Then, at a point in time at which the trigger of the control cycle has been input, a new target rotation speed (the number of rotations) is obtained by subtracting a predetermined subtraction amount from the target rotation speed (the number of rotations) of the current time point (step S16). Then, the driving control unit42obtains a lead angle corresponding to the newly obtained number of rotations by referring to the lead angle map stored in the lead angle map storage unit44(step S17). Subsequently, the driving control unit42outputs a command for setting the obtained target rotation speed value and lead angle as a new target rotation speed and lead angle to the motor-driving unit3(step S18). Until the operation end position is reached, the driving control unit42iterates processing operations of steps S12to S18. At a point in time at which the operation end position has been reached, the rotation of the motor2is stopped. Thereby, the motor2reaches the operation end position while the rotation speed decreases, as illustrated inFIG. 3. At this time, because an optimum lead angle corresponding to the number of rotations is set, the motor2can efficiently rotate.

Also, although the parameter storage unit43in which five control parameters are associated and stored for each input signal pattern is provided in the control unit4, the five control parameters are selected according to an input signal, and the rotation of the motor2is controlled based on the selected control parameters in the above description, the five control parameters may be input from the outside (a computer which generally controls the operation of the vehicle, or the like) of the control unit4and the driving control unit42may be configured to control the rotation of the motor2based on the input five control parameters. This is possible because the target rotation speed is obtained by an arithmetic operation inside the driving control unit42. In addition, although the new target rotation speed is obtained by adding or subtracting a predetermined amount in the above description, a value of the target rotation speed determined for each angle in advance may be used based on an output in the angle sensor21.

In addition, although the lead angle map illustrated inFIG. 4is shown as an example in which the number of rotations of the motor and the lead angle to be set are associated for each of the forward rotation and the reverse rotation, it is possible to constantly rotate a motor in a state in which characteristics of the motor are good and suppress power consumption and heat generation if a lead angle map in which the number of rotations of the motor of the forward rotation and the positive lead angle are associated is used in the case of rotation in only one direction.

As described above, it is possible to constantly rotate a motor in a state in which characteristics of the motor are good and suppress power consumption and heat generation because a lead angle map in which a motor rotation speed (the number of rotations) and a lead angle are associated is stored for each of forward and reverse rotations within the control unit4and the lead angle corresponding to a newly obtained target rotation speed is also varied according to variation in a target rotation speed.

In addition, the wiper control process may be implemented by recording a program for implementing the function of the control unit4inFIG. 1on a computer-readable recording medium and causing a computer system to read and execute the program recorded on the recording medium. The term “computer system” used herein may include an operating system (OS) and/or hardware such as peripheral devices. In addition, the term “computer-readable recording medium” refers to a storage device including a flexible disk, a magneto-optical disc, a read only memory (ROM), a portable medium such as a compact disc-ROM (CD-ROM), and a hard disk embedded in the computer system. Further, the term “computer-readable recording medium” may include a computer-readable recording medium for holding programs for a predetermined time such as a volatile memory (random access memory (RAM)) inside a computer system including a server and a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line.

In addition, the above-described program may be transmitted from a computer system storing the program in a storage device or the like to other computer systems via a transmission medium or transmission waves of the transmission medium. Here, the term “transmission medium” for transmitting the program refers to a medium having a function of transmitting information like a network (communication network) such as the Internet or a communication line (communication wire) such as a telephone line. The above-described program may be used to implement some of the above-described functions. Further, the program may be a so-called differential file (differential program) capable of implementing the above-described functions in combination with a program already recorded on the computer system.

INDUSTRIAL APPLICABILITY

The present invention can be applied to a controlling operation of an object to be controlled via a link mechanism connected to a rotary shaft of a motor and, for example, can also be applied to control an operation of an electric tailgate, a slide door, a power window, etc. provided in a vehicle.

REFERENCE SIGNS LIST

41Signal input unit

42Driving control unit

43Parameter storage unit

44Lead angle map storage unit