JP6348830B2 - Electric steering device - Google Patents

Description

The present invention relates to an electric steering apparatus, and more particularly to an electric steering apparatus suitable for application to a vehicle equipped with an RTC (Rear Toe Control ) or the like .

  Patent Document 1 describes that a capacitor is charged with a voltage higher than that of a power source from a current source having a boosting function and a current limiting function, and motor driving is performed in the capacitor.

  In Patent Document 2, boosting is performed when the remaining battery level is present, and the upper limit of the motor current to be supplied is increased, but when the remaining capacity is low (determined by voltage), the boosting is stopped and the upper limit of the motor current is decreased, It is described that the steering input of the driver is prevented from excessively increasing by lowering the motor assist torque target value.

  In Patent Document 3, an input current from a power source to an ECU (electronic control unit) is calculated from an expression for calculating electric power required by a load side and a motor required current, and is limited to the current value. It describes preventing overcurrent.

JP 2007-091045 A JP 2007-283953 A JP 2009-078711 A

By the way, in a vehicle equipped with RTC (rear toe control ) or the like , when performing rapid repeated steering (double lane change or the like), there is a case where power is insufficient and the first and second steering feelings are different. For example, in the first time, the assist to the RTC and the steering functions following the rapid steering, but in the second time, the assist function may not be able to follow the rapid steering due to power shortage.

Patent Documents 1 to 3, because it does not assume a rapid repetition steering in a vehicle equipped with a RT C, etc. (double lane change or the like), it is impossible to solve the problems as described above.

  In particular, the RTC has an actuator at the rear of the vehicle, is generally far from a power supply device at the front of the vehicle, and has high wiring resistance. For this reason, there is a problem that a voltage drop is likely to occur and an operation with high responsiveness to cope with a rapid steering is difficult.

The present invention has been made taking the foregoing problems into consideration, in the vehicle equipped with the RT C, etc., to predict the situation of performing rapid repetition steering (double lane change or the like), first quick steering and 2 It is an object of the present invention to provide an electric steering apparatus capable of managing electric power and driving an actuator or the like so that the first rapid steering gives a similar steering feeling.

  The vehicle to which the present invention is applied includes an internal combustion engine and / or a drive motor as a vehicle drive source. In addition to an internal combustion engine vehicle, an EV (electric vehicle), an HEV (hybrid vehicle), and a PHEV. Electric vehicles such as (plug-in hybrid vehicles) and FCVs (fuel cell vehicles) are included.

[1] An electric steering apparatus according to the present invention is an electric steering apparatus that applies assist force to a rear toe control of a vehicle using a motor as a drive source, and includes a main power source and a drive circuit that supplies drive power to the motor. In the middle of the power supply path between them, a current source having a boosting function capable of limiting the output current value to a predetermined value and boosting the power supply voltage and outputting it, and storing the output power of the current source to store the drive circuit and sub-power that can be supplied to a means for detecting a rapid steering by oPERATION's and a control unit, the current source is composed of a DC-DC converter with a built-in capacitor, wherein the control unit, the operation When the next rapid steering is detected within a predetermined time after the first rapid steering is detected by the person, the drive power in the first rapid steering and the drive power in the next rapid steering are as much as possible It will be Thus, the current source and the sub power source are controlled .

  The present invention, for example, in a vehicle equipped with RTC (rear toe control), when performing a double lane change, can appropriately distribute the amount of operation of the RTC according to the state of charge of the sub power supply, giving the driver a sense of incongruity Can be suppressed. Moreover, even when the main power supply is installed at the front of the vehicle and the actuator is installed at the rear of the vehicle, and the wiring resistance of the power supply path between them is large, a current source having a boosting function is installed in the power supply path Therefore, the voltage drop due to the wiring resistance can be suppressed, and the output of the motor can be improved.

[2] In the present invention, based on the detection of the rapid steering of the first, and the assist amount of the first with respect to the rear toe control, based on the detection of the next rapid steering, the next assist amount for the rear toe control, as an absolute value It may be equivalent.

  Equivalent means a level that does not give the driver a sense of incongruity. For this reason, the operation amount for the first rapid steering and the operation amount for the next rapid steering are equal in absolute value, which may occur when a double lane change is performed in a vehicle equipped with an RTC. Can suppress a sense of incongruity.

[3] In the present invention, when the state of charge of the sub power source is equal to or less than a predetermined value, the application of assist force to the rear toe control may be stopped.

  If the secondary power supply is not fully charged, the amount of operation will be less than the amount of operation for the first rapid steering even if the power from the secondary power supply is used for the next rapid steering. There is a risk of giving. Therefore, by stopping the assist operation for the RTC from the stage of the first rapid steering, it is possible to save the charging power of the sub power supply, and the small turn does not work, but it is possible to suppress the uncomfortable feeling due to the difference in the operating force. it can.

[4] In the present invention, the means for detecting the rapid steering detects the rapid steering when the steering speed of the vehicle steering is equal to or higher than a preset threshold, and detects after the predetermined time has elapsed. Rapid steering may be detected as the first rapid steering. In the RTC, it is dominant to determine the operation amount based on the behavior of the vehicle, so the driver's steering is faster as an event. That is, since the driver operates in the order of steering → vehicle behavior → RTC operation, rapid steering can be detected at an early stage by detecting rapid steering based on the steering speed, and RTC following the rapid steering can be detected. Can be realized.

[5] In the present invention, at least the first rapid steering detection by the rapid steering detection unit may be performed based on an obstacle detection.

  Since double lane changes are often performed when avoiding obstacles, rapid steering can be detected at an early stage by performing at least initial rapid steering detection based on obstacle detection. The operation of the RTC following the rapid steering can be realized.

According to the present invention, in a vehicle equipped with the RT C, etc., to predict the situation of performing rapid repetition steering (double lane change or the like), a first quick steering and second quick steering similar steering feeling In this way, the actuator can be driven by managing the power.

It is a block diagram which shows the structure of the electric steering apparatus which concerns on this Embodiment. It is a figure which shows the characteristic of the 1st supply power with respect to a supply current, and the characteristic of the 2nd supply power with respect to a supply current. FIG. 3A is an explanatory diagram showing an example of a double lane change, and FIG. 3B is a waveform diagram showing changes in the steering speed of the first rapid steering and the next rapid steering. It is a flowchart (the 1) which shows the processing operation of the electric steering apparatus which concerns on this Embodiment. It is a flowchart (the 2) which shows the processing operation of the electric steering apparatus which concerns on this Embodiment. FIG. 6A is an explanatory diagram showing an operation when the sub power source is not fully charged in normal running with a circuit diagram, and FIG. 6B is an explanatory diagram showing an operation when the sub power source is fully charged in normal running with a circuit diagram. FIG. 7A is an explanatory diagram showing an operation corresponding to the first rapid steering when the sub power supply is fully charged together with a circuit diagram, and FIG. 7B is an explanatory diagram showing an operation corresponding to the next rapid steering together with a circuit diagram. . FIG. 8A is an explanatory diagram showing an operation corresponding to the first rapid steering with the circuit diagram when the first method is adopted, and FIG. 8B is an explanatory diagram showing an operation corresponding to the next rapid steering together with the circuit diagram. . FIG. 9A is an explanatory diagram showing an operation corresponding to the first rapid steering with the circuit diagram when the second method is adopted, and FIG. 9B is an explanatory diagram showing an operation corresponding to the next rapid steering together with the circuit diagram. . FIG. 10A is an explanatory diagram showing an operation corresponding to the first rapid steering with the circuit diagram when the third method is adopted, and FIG. 10B is an explanatory diagram showing an operation corresponding to the next rapid steering together with the circuit diagram. .

  Embodiments of an electric steering apparatus according to the present invention will be described below with reference to FIGS.

  First, as shown in FIG. 1, an electric steering apparatus 10 according to the present embodiment is an application of the electric steering apparatus according to the present invention to a rear toe control (hereinafter referred to as RTC) of a vehicle. The RTC changes the toe angle of the rear wheel based on the steering angle of the steering and the vehicle speed. The electric steering device applies assist force to the RTC using a motor as a drive source.

  That is, the electric steering device 10 includes a motor 12, a motor drive circuit 14 that supplies driving power to the motor 12, and an actuator 18 that changes the toe angle of the rear wheel 16 by converting the rotational force of the motor 12 into a linear motion. And having. The rear wheel 16 typically represents one rear wheel, but there may be two or more. When there are a plurality of rear wheels, the electric steering device 10 may be installed for each rear wheel, or one electric steering device 10 may be installed for two rear wheels.

  The electric steering apparatus 10 further includes a current (first electric current) supplied from the current source 20, the auxiliary power source 22, the rapid steering determination unit 24, the control unit 26, and the main power source 27 (battery) of the vehicle to the current source 20. A first current detector 28a for detecting a supply current value I1), a first voltage detector 30a for detecting a voltage (first voltage value V1) applied to the current source 20, and a current output from the current source 20. Applied to the output voltage detector 32 for detecting (output current value Io), the second current detector 28b for detecting the current (second supply current value I2) supplied to the motor drive circuit 14, and the motor drive circuit 14 A second voltage detection unit 30b that detects the voltage (second voltage value V2) to be detected, and a sub power supply voltage detection unit 34 that detects the voltage value Va across the sub power supply 22.

  The current source 20 is inserted and connected in the middle of the power supply path 36 between the vehicle main power supply 27 and the motor drive circuit 14. The current source 20 has a boosting function that limits the output current value Io to a predetermined value and boosts the power supply voltage for output. The current source 20 can be configured by, for example, a step-up chopper type DC-DC converter including a capacitor 35, and limits the output current value Io to a current value based on an instruction signal from the control unit 26.

  The sub power supply 22 is connected between the power supply path 36 between the current source 20 and the motor drive circuit 14 and the ground, and can store the output power of the current source 20 and supply it to the motor drive circuit 14. Specifically, a capacitor 38 connected between the power supply path 36 and the ground, and a switch 40 connected between the power supply path 36 and the capacitor 38 are included. The switch 40 performs an opening / closing operation based on switching signals (ON signal So, OFF signal Sf) from the control unit 26. This will be described later.

  The rapid steering discriminating unit 24 discriminates whether or not rapid steering is performed based on the steering speed vθ obtained by differentiating the steering angle θ from the steering angle sensor 42 of the steering. For example, when the obtained steering speed vθ is equal to or higher than a preset threshold value vθth, the rapid steering detection signal Sa is output to the control unit 26 assuming that rapid steering is performed.

  The control unit 26 includes a current limit instruction unit 44, a supply current calculation unit 46, a charge / discharge instruction unit 48, and an operation stop instruction unit 50.

  In the case of normal running, the current limit instruction unit 44 determines that the output current value Io from the current source 20 includes power supplied to the current source 20 (denoted as first supply power P1) and power supplied to the motor drive circuit 14 ( The attribute of the control signal Sc to the current source 20 is changed so that the current value (first target current value Io1) having the largest difference from the second supply power P2) is obtained. If the current source 20 is, for example, a DC-DC converter having a switching regulator, the pulse width of the switching control signal applied to the gate of the semiconductor switch is changed. The second supply power P2 is also power consumption in the motor 12.

  Here, the characteristic of the first supply power P1 with respect to the supply current is a characteristic that is convex upward as shown by a curve Da in FIG. On the other hand, the characteristic of the second supply power P2 with respect to the supply current is such that the second supply power P2 increases proportionally as the second supply current value I2 increases, as shown by the straight line Db in FIG. .

  The straight line Db passes through the vertex 52 of the curve Da. In the supply current range Za lower than the supply current corresponding to the apex 52, the relationship is the first supply power P1> the second supply power P2, and the difference is a margin Pa. Within this range Za, a supply current value having the largest difference (margin Pa) between the first supply power P1 and the second supply power P2 is obtained in advance by experiment or simulation, and this supply current value is determined as the first target current value. Io1 is registered in the first register R1 in the control unit 26.

  Moreover, the electric power corresponding to the vertex 52 among the 1st supply electric power P1 is the maximum value of the 1st supply electric power P1. The supply current value corresponding to the maximum first supply power P1 is registered in the second register R2 in the control unit 26 as the second target current value Io2. The maximum value of the first supply power P <b> 1 varies depending on the motor 12 installed in the electric steering apparatus 10, and is a predetermined maximum power value set based on the motor 12.

  Then, the current limit instructing unit 44 reads the first target current value Io1 from the first register R1 during normal running so that the output current value Io from the current source 20 becomes the first target current value Io1. The attribute (for example, pulse width) of the control signal Sc to the current source 20 is changed.

  When there is rapid steering (first rapid steering), the supply current calculating unit 46 performs the second supply current value I2 by the first rapid steering and the second rapid current steering that will occur within the predetermined time Ta. The supply current value I2 is calculated. This calculation is performed based on the charging state of the sub power source 22. The predetermined time Ta is a time sufficient for charging the capacitor 35 of the current source 20. The capacitor 35 is set to be able to be charged with power (referred to as maximum charging power) corresponding to the maximum first supply power P1 (see FIG. 2). The predetermined time Ta is set to a time sufficient for the maximum charging power to be charged from the state where the capacitor 35 of the current source 20 is not charged.

  A typical example where rapid steering is repeated twice in a short time is a double lane change. In the double lane change, as shown by an arrow A in FIG. 3A, for example, a vehicle (not shown) traveling straight in the first lane L1 rapidly steers to the left side (first rapid steering) at a certain point, for example. As soon as the vehicle moves to the second lane L2, there is a case where the vehicle travels straight by rapidly steering to the right side (next rapid steering). Of course, as soon as the vehicle traveling straight on the second lane L2 steers rapidly to the right side (first rapid steering) and moves to the first lane L1 at a certain point, the vehicle rapidly steers to the left side (next rapid Steering) and go straight ahead.

  As described above, the supply current calculation unit 46, when there is an initial rapid steering, in addition to the second supply current value I2 by the initial rapid steering, the next rapid steering that will occur within a predetermined time Ta. The second supply current value I2 is also calculated. Then, as shown in FIG. 3B, the next time calculated in advance is the first time when the time Tb from the time t1 when the first rapid steering is detected to the time t2 when the next rapid steering is detected is shorter than the predetermined time Ta. Thus, the second supply current value I2 by rapid steering is applied.

  The supply current calculation unit 46 calculates the second supply current value I2 as follows.

  When the charging state of the sub power source 22 is full, the output current value Io from the current source 20 by the first rapid steering is set as the second target current value Io2 stored in the second register R2 (see FIG. 7A). This second target current value Io2 becomes the second supply current value I2 by the first rapid steering. The second supply current value I2 by the next rapid steering becomes the discharge current value Id from the sub power supply 22 (see FIG. 7B). In this case, since the same current value (both the second target current value Io2) is supplied to the motor drive circuit 14 at the first time and the next time, the first operation amount (assist amount) for the RTC and the next operation amount (assist amount). Can be made the same as an absolute value, and an operation amount based on the maximum supply power can be obtained both at the first time and the next time. “As an absolute value” indicates that the steering direction is not taken into consideration when the magnitude relation of the assist amount is viewed. The same applies hereinafter.

  When the charging state of the sub power supply 22 is not fully charged (except when the charging state is not sufficient), there are three methods (first method to third method).

  In the first method, the output current value Io from the current source 20 by the first rapid steering is set as the second target current value Io2 stored in the second register R2. Also in this case, the second target current value Io2 becomes the second supply current value I2 by the first rapid steering (see FIG. 8A). The second supply current value I2 by the next rapid steering becomes the discharge current value Id from the sub power supply 22 (see FIG. 8B). In this first method, different current values are supplied to the motor drive circuit 14 between the first time and the next time. The second target current value Io2 is supplied for the first time, and the discharge current value Id (<Io2) is supplied for the next time. Therefore, the next operation amount (assist amount) is slightly smaller than the first operation amount (assist amount) for the RTC. Therefore, the difference between the first operation amount (absolute value) and the next operation amount (absolute value) is small, and the first operation amount and the next operation amount are so small that the driver does not feel uncomfortable between the first operation and the next operation. Are considered to be equivalent to the absolute value.

  In the second method, the discharge current value Id of the sub power source 22 is calculated from the voltage value Va across the sub power source 22. Then, the output current value Io from the current source 20 by the first rapid steering is set as the calculated discharge current value Id. This output current value Io becomes the second supply current value I2 by the first rapid steering (see FIG. 9A). The second supply current value I2 by the next rapid steering becomes the discharge current value Id from the sub power supply 22 (see FIG. 9B). In the second method, since the first second supply current value I2 is set to the calculated discharge current value Id of the sub power source 22, the supply power is lower than the maximum supply power both at the first time and the next time. The operating amount and the next operating amount can be made the same as an absolute value.

  In the third method, the discharge current value Id of the sub power source 22 is determined from the voltage value Va across the sub power source 22. Then, the average value Iave (= (Io2 + Id) / the second target current value Io2 stored in the second register R2 and the calculated discharge current value Id is the output current value Io from the current source 20 by the first rapid steering. 2). This average value Iave becomes the second supply current value I2 by the first rapid steering (see FIG. 10A). The output current value Io from the current source 20 by the next rapid steering is a current value obtained by subtracting the above-mentioned average value Iave from the second target current value Io2. This current value and the discharge current value Id from the sub power supply 22 are combined to form a second supply current value I2 (see FIG. 10B). Even in the third method, the power supply is lower than the maximum power supply for both the first time and the next time, but the first operation amount and the next operation amount can be made the same as an absolute value. In addition, since both the first and next second supply current values I2 can be set to (Io2 + Id) / 2 (> Id), the first and next supply power can be made larger than in the second method.

  The current limit instruction unit 44 sets the attribute (for example, pulse width) of the control signal Sc to the current source 20 so that the second supply current value I2 becomes the supply current value calculated by the supply current calculation unit 46. change.

  The charge / discharge instruction section 48 outputs an on signal So for turning on the switch 40 when the sub power supply 22 is not fully charged during normal driving of the vehicle. As a result, a part (a margin Pa) of the first supply power P1 is charged to the sub power supply 22 via the switch 40. The charge / discharge instruction unit 48 outputs an off signal Sf for turning off the switch 40 when the sub power supply 22 is fully charged during normal driving of the vehicle. As a result, the switch 40 is turned off and the sub power supply 22 is disconnected from the power supply path 36.

  When the secondary power source 22 is fully charged, the secondary power source 22 has an amount of charge sufficient to output a second supply current value I2 corresponding to the maximum second supply power (see the characteristic diagram of FIG. 2) from the secondary power source 22 during discharging. Accumulated state. The voltage value Va at this time is obtained in advance by experiment or simulation, and the voltage value Va at both ends is stored in the third register R3 of the control unit 26 as the upper limit threshold value Vath1. Then, the charge / discharge instruction unit 48 determines that the sub power source 22 is in a fully charged state when the both-end voltage value Va from the sub power source voltage detecting unit 34 becomes equal to or higher than the upper limit threshold value Vath1, and turns off the switch 40. Sf is output.

  Furthermore, when the first rapid steering is detected, the charge / discharge instruction unit 48 outputs an off signal Sf to the switch 40 to turn off the switch 40. As a result, the power supply to the motor drive circuit 14 based on the first rapid steering is made only from the current source 20. When the next rapid steering is detected within a predetermined time Ta from the time t1 when the first rapid steering is detected (see FIG. 3B), the charge / discharge instruction unit 48 outputs an ON signal So to the switch 40, and the switch Turn on 40. As a result, power supply to the motor drive circuit 14 based on the next rapid steering is performed only from the sub power source 22 or from the current source 20 and the sub power source 22.

  When the initial rapid steering is detected, the operation stop instructing unit 50, when the charging state of the sub power source 22 is not sufficient, the motor drive circuit 14 for a certain time Tc from the time when the initial rapid steering is detected. The stop signal Ss is output to The motor drive circuit 14 stops power supply to the motor 12 during the input period of the stop signal Ss. That is, the assist operation for the RTC is stopped. The fixed time Tc may be a time sufficient for charging the capacitor 35 of the current source 20 and may be the same as the predetermined time Ta.

  Here, the state of charge at the sub power supply 22 is not sufficient when the sub power supply 22 is discharged so that the current value obtained by multiplying the second target current value Io2 by the coefficient k1 (0 <k1 <1) is output. This is a state where only the amount is accumulated in the sub power source 22. The voltage value Va at this time is obtained in advance through experiments and simulations, and this voltage value Va is stored in the fourth register R4 of the control unit 26 as the lower limit threshold value Vath2. Then, when the first rapid steering is detected, the operation stop instructing unit 50 determines that the sub power supply 22 is not charged when the both-end voltage value Va from the sub power supply voltage detecting unit 34 is less than the lower threshold value Vath2. The stop signal Ss is output to the motor drive circuit 14 for a predetermined time Tc.

  The coefficient k1 is preferably set in consideration of the following matters. That is, the coefficient k1 is also a parameter that determines an allowable range (in particular, a lower limit value) of the next second supply current value I2. When, for example, the first method is employed as the calculation method in the above-described supply current calculation unit 46, if the coefficient k1 is too small, the next second supply current value I2 is operated as compared to the first second supply current value I2. There is a risk that it will be small enough to make the person feel uncomfortable. If the coefficient k1 is too large, the operation of the motor drive circuit 14 may frequently stop. Therefore, the coefficient k1 is set in a range in which the driver does not feel uncomfortable and the operation of the motor drive circuit 14 does not stop frequently. For example, the range of 3 / 4-5 / 6 etc. are mentioned.

  Next, the processing operation of the electric steering apparatus 10 according to the present embodiment will be described with reference to FIGS. 4 to 10B.

  First, in step S1 of FIG. 4, the rapid steering determination unit 24 determines whether or not steering has been performed. This determination is made based on the steering angle value θ from the steering angle sensor 42 of the steering.

  In step S2, the rapid steering determining unit 24 determines whether or not the current steering is rapid steering. This determination is made based on whether or not the steering speed obtained by differentiating the steering angle value θ from the steering angle sensor 42 is equal to or greater than the threshold value vθth.

  If it is not rapid steering, it will be normal driving | running | working and it will progress to step S3, and the charge / discharge instruction | indication part 48 will discriminate | determine whether the sub power supply 22 is a full charge state. This determination is made based on whether or not the voltage value Va across the sub power supply 22 is equal to or higher than the upper threshold value Vath1.

  If the sub power supply 22 is not fully charged, the process proceeds to step S4, and the charge / discharge instruction unit 48 outputs an ON signal So to the switch 40. As a result, the switch 40 is turned on, and the sub power supply 22 is electrically connected to the power supply path 36.

  If the sub power supply 22 is in a fully charged state, the process proceeds to step S5, and the charge / discharge instruction unit 48 outputs an off signal Sf to the switch 40. As a result, the switch 40 is turned off, and the sub power supply 22 is electrically disconnected from the power supply path 36.

  When the process in step S4 or step S5 is completed, the process proceeds to step S6, and the current limit instruction unit 44 reads the first target current value Io1 (the supply current value with the largest margin Pa) from the first register R1. The attribute (for example, pulse width) of the control signal Sc to the current source 20 is changed so that the second supply current value I2 becomes the first target current value Io1.

  As a result, when the sub power supply 22 is not fully charged, the first target current value Io1 is supplied to the motor drive circuit 14 out of the output current value Io from the current source 20, as shown in FIG. A current value Ie corresponding to a margin Pa is supplied to the power supply 22. In this case, the first supply current value I1 from the main power supply 27 is increased by the boosting of the current source 20. That is, of the first supply power P1 from the main power supply 27, the power corresponding to the second supply current value I2 is consumed by the motor 12, and the remaining margin Pa is charged to the sub power supply 22.

  If the sub power supply 22 is in a fully charged state, as shown in FIG. 6B, the output current value Io from the current source 20 is supplied to the motor drive circuit 14 as the second supply current value I2. In this case, the boost of the current source 20 consumes power corresponding to the first supply power P1 by the motor 12, and the output of the motor 12 is improved.

  In the next step S <b> 7, the control unit 26 determines whether or not there is a termination request (power cut, maintenance, etc.) to the electric steering device 10. If there is no end request, the process returns to step S1, and the processes after step S1 are repeated.

  On the other hand, if it is determined in step S2 that the current steering is rapid steering, the process proceeds to step S8 in FIG. 5, and the control unit 26 sets the current rapid steering as the initial rapid steering for a predetermined time Ta. Start timing.

  Thereafter, in step S9, the operation stop instruction unit 50 determines whether or not the charging state of the sub power source 22 is sufficient. This determination is made based on whether or not the voltage value Va across the sub power supply 22 is equal to or greater than the lower threshold value Vath2 stored in the fourth register R4.

  If the charging state of the sub power supply 22 is sufficient, the process proceeds to step S10, and the charge / discharge instruction unit 48 determines whether or not the sub power supply 22 is fully charged. If the battery is fully charged, the process proceeds to step S11, and the supply current calculator 46 sets the second target current value Io2 stored in the second register R2 as the output current value Io from the current source 20 by the first rapid steering. To do.

  If not fully charged, the process proceeds to step S12, and the supply current calculation unit 46 calculates the first second supply current value I2, that is, the output current value Io from the current source 20, in the first to third methods. Of these, calculation (setting) is performed according to a preset method. Since the calculation method has already been described, the description thereof is omitted here. In the case of the third method, in step S12, in addition to the first second supply current value I2, the output current value Io from the current source 20 for the next rapid steering is also set.

  When the process in step S11 or step S12 ends, the process proceeds to the next step S13, and the charge / discharge instruction unit 48 outputs an off signal Sf to the switch 40 to disconnect the sub power supply 22 from the power supply path 36.

  In step S 14, the first second supply current value I 2 for the first rapid steering is supplied to the motor drive circuit 14. Specifically, the current limit instruction unit 44 reads the current value set by the calculation in step S11 or step S12, and supplies the current source 20 to the current source 20 so that the second supply current value I2 becomes the current value. The attribute (for example, pulse width) of the control signal Sc is changed. As a result, the first second supply current value I2 is supplied to the motor drive circuit 14.

  That is, when the sub power supply 22 is fully charged, as shown in FIG. 7A, the current value adjusted to the second target current value Io2 is output from the current source 20, and the motor is driven as the first second supply current value I2. It is supplied to the circuit 14. Also in the case of the first method, as shown in FIG. 8A, the current value adjusted to the second target current value Io2 is output from the current source 20 and supplied to the motor drive circuit 14. In the case of the second method, as shown in FIG. 9A, the current value adjusted to the discharge current value Id (discharge current value determined by the second method) of the sub power source 22 is output from the current source 20, It is supplied to the motor drive circuit 14. In the case of the third method, as shown in FIG. 10A, a current value adjusted to an average value Iave of the second target current value Io2 and the discharge current value Id of the sub power supply 22 is output from the current source 20, and the motor drive It is supplied to the circuit 14.

  Thereafter, in step S15, the rapid steering determination unit 24 determines whether or not steering is performed.

  In step S16, the rapid steering determination unit 24 determines whether or not the current steering is rapid steering. If it is rapid steering, it will progress to step S17 and the control part 26 will discriminate | determine whether it is in predetermined time Ta from the time-measurement start time of predetermined time Ta in step S8. If it is within the predetermined time Ta, the process proceeds to step S18.

  In step S18, the second second supply current value I2 for the second rapid steering is supplied to the motor drive circuit 14. Specifically, when the sub power supply 22 is fully charged, or when the calculation method is the first method or the second method, the charge / discharge instruction unit 48 outputs an ON signal So to the switch 40, and the sub power supply 22. Is connected to the power supply path 36. As a result, the discharge current value Id from the sub power supply 22 is supplied to the motor drive circuit 14 as the second supply current value I2 for the second time.

  On the other hand, when the calculation method is the third method, the output current value from the current source 20 for the next rapid steering calculated in step S12 (the current value obtained by subtracting the average value Iave from the second target current value Io2 (Io2 -Iave)) is read, and the attribute (for example, pulse width) of the control signal Sc to the current source 20 is changed so that the output current value Io from the current source 20 becomes the read current value (Io2-Iave). To do. As a result, a current value (Io2-Iave) is output from the current source 20. Further, the charge / discharge instruction unit 48 outputs an ON signal So to the switch 40 to connect the sub power supply 22 to the power supply path 36. As a result, the current value (Io2-Iave) from the current source 20 and the discharge current value Id from the sub power source 22 are combined and supplied to the motor drive circuit 14 as the second supply current value I2 for the second time.

  That is, when the sub power supply 22 is fully charged, as shown in FIG. 7B, the current value corresponding to the discharge current value Id of the sub power supply 22 is supplied to the motor drive circuit 14 as the second second supply current value I2. Supplied. Also in the case of the first method and the second method, a current value corresponding to the discharge current value Id of the sub power supply 22 is supplied to the motor drive circuit 14 as shown in FIGS. 8B and 9B. In the case of the third method, as shown in FIG. 10B, the current value adjusted to the current value (Io2-Iave) is output from the current source 20, and the current value corresponding to the discharge current value Id is output from the sub power source 22. Is output. As a result, a current value obtained by summing the current value (Io2-Iave) and the discharge current value Id is supplied to the motor drive circuit 14.

  If it is determined in step S17 that the second rapid steering has been performed after a predetermined time Ta, the second rapid steering is regarded as the first rapid steering, and the process returns to step S8. The processes after step S8 are repeated.

  On the other hand, when it is determined in step S16 described above that the current rapid steering is not the second rapid steering, the process returns to step S3 in FIG. 4 to repeat the processing after step S3.

  If it is determined in step S9 that the charging state at the sub power source 22 is insufficiently charged, the process proceeds to step S19, and the operation stop instruction unit 50 stops the motor drive circuit 14 for a certain time Tc. The signal Ss is output. The motor drive circuit 14 stops power supply to the motor 12 during the input period of the stop signal Ss. That is, the assist operation for the RTC is stopped.

  When the process in step S18 or the process in step S19 is completed, the process returns to step S1 in FIG. 4 and the processes in and after step S1 are repeated.

  Then, when it is determined in step S7 in FIG. 4 that the request is an end request, the processing in the electric steering apparatus 10 ends.

  Normally, in a vehicle equipped with an RTC or the like, when performing rapid repeated steering (double lane change or the like), depending on the state of power supply from the main power supply 27, the assist operation for the first rapid steering and the second There may be a difference in the assist operation for rapid steering. For example, in the first time, the assist operation to the RTC functions following the rapid steering, but in the second time, the assist operation cannot follow the rapid steering due to insufficient power. In such a case, there is a risk of giving the driver a feeling of strangeness in steering. In addition, since the actuator 18 is located at the rear of the vehicle, the RTC is generally far from the main power supply 27 located at the front of the vehicle and has a large wiring resistance. For this reason, there is a problem that a voltage drop is likely to occur and an operation with high responsiveness to cope with a rapid steering is difficult.

  However, in the electric steering apparatus 10 according to the present embodiment, when a double lane change is performed in a vehicle equipped with an RTC, the operation amount of the RTC can be appropriately distributed according to the charging state of the sub power supply 22. It is possible to suppress the uncomfortable feeling given to the driver. Moreover, even if the main power supply 27 is installed at the front of the vehicle and the actuator 18 and the like are installed at the rear of the vehicle, and the wiring resistance of the power supply path 36 therebetween is large, the power supply path 36 has a boosting function. Since the current source 20 is installed, the voltage drop due to the wiring resistance can be suppressed, and the output of the motor 12 can be improved.

  Further, in the present embodiment, as can be seen from the calculation method according to the charging state of the sub power supply 22 in the supply current calculation unit 46, the input of the steering speed (first rapid steering) equal to or higher than the initial threshold value vθth. The operation amount of the electric steering device 10 based on the above and the operation amount of the electric steering device 10 based on the input of the steering speed (next rapid steering) equal to or higher than the next threshold value vθth are made equal as absolute values. “Equivalent” refers to a level that does not give the driver a sense of incongruity, as described above. For this reason, the operation amount for the first rapid steering and the operation amount for the next rapid steering are equal in absolute value, which may occur when a double lane change is performed in a vehicle equipped with an RTC. Can suppress a sense of incongruity.

  Further, in the present embodiment, when the sub power supply 22 is not sufficiently charged, a stop signal Ss is output to the motor drive circuit 14 for a predetermined time Tc to stop the power supply to the motor 12. Yes. That is, the assist operation for the RTC is stopped for a certain time Tc. If the charging state of the auxiliary power source 22 is not sufficient, the operating amount is smaller than the operating amount for the first rapid steering even if the power of the auxiliary power source 22 is used for the next rapid steering. May give a sense of incongruity. Therefore, by stopping the assist operation for the RTC from the initial rapid steering stage, it is possible to save the charging power of the sub power source 22 and the small turn does not work, but to suppress the uncomfortable feeling due to the difference in the operating force. Can do.

  In the present embodiment, the first rapid steering is detected based on the input of the steering speed equal to or higher than the first threshold vθth, and the next rapid steering is detected based on the steering speed equal to or higher than the next threshold vθth. Based on input. In the RTC, it is dominant to determine the operation amount based on the behavior of the vehicle, so the driver's steering is faster as an event. That is, since the driver operates in the order of steering → vehicle behavior → RTC operation, rapid steering can be detected at an early stage by detecting rapid steering based on the steering speed, and RTC following the rapid steering can be detected. Can be realized.

  In the above example, the rapid steering determination unit 24 detects the rapid steering based on the steering speed. However, the following method may be used.

  That is, the rapid steering determination unit 24 outputs a rapid steering detection signal Sa to the control unit 26 when an obstacle is detected based on an image from a camera (not shown), a reflected wave of an output wave from a radar, or the like. Also good. Since double lane changes are often performed when avoiding obstacles, rapid steering can be detected at an early stage by performing at least initial rapid steering detection based on obstacle detection. The operation of the RTC following the rapid steering can be realized.

  Alternatively, the rapid steering determination unit 24 may determine whether rapid steering is performed based on a signal from the collision avoidance support control system. The collision avoidance assistance control system outputs the possibility of collision with an obstacle or another vehicle as numerical data based on an image from a camera (not shown), a reflected wave of an output wave from a radar, or the like. The rapid steering determination unit 24 outputs a rapid steering detection signal Sa to the control unit 26, assuming that rapid steering is performed when the numerical data from the collision avoidance support control system is equal to or greater than a threshold value.

  In the above example, the electric steering apparatus 10 according to the present embodiment is applied to the RTC. However, the electric steering apparatus 10 may be applied to a power steering apparatus that assists the steering of the front wheels. In this case, the actuator 18 converts the rotational force of the motor 12 into a linear motion and steers the front wheels. Of course, for a vehicle equipped with an RTC and a power steering device, the electric steering device may be applied individually to the RTC and the power steering device.

[Summary of embodiment]
As described above, the electric steering apparatus 10 according to the present embodiment is an electric steering apparatus that applies assist force to the steering system using the motor 12 as a driving source, and supplies driving power to the main power supply 27 and the motor 12. A current source 20 having a boosting function capable of limiting the output current value Io to a predetermined value and boosting the power supply voltage and outputting it in the middle of the power supply path 36 between the motor driving circuit 14 and the current source 20 And an auxiliary power source 22 that can store the output power of the motor and supply it to the motor drive circuit 14, and further includes means for detecting rapid steering by the driver, and when the first rapid steering by the driver is detected. Based on the state of the sub power source 22, the drive power is controlled so that the next rapid steering occurring within the predetermined time Ta can be handled.

  In the present embodiment, the first operation amount based on the first rapid steering detection and the next operation amount based on the next rapid steering detection may be equivalent as absolute values.

  In the present embodiment, when the charging state of the sub power supply 22 is a predetermined value (the voltage value Va across the sub power supply 22 is less than the lower limit threshold value Vath2), the application of assist force to the steering system is stopped. Good.

  In the present embodiment, at least the initial rapid steering may be detected based on an input of a steering speed (vθ) that is equal to or greater than the initial predetermined value (threshold value vθth).

  In the present embodiment, at least the first rapid steering may be detected based on the detection of an obstacle.

  Note that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted based on the content described in this specification.

DESCRIPTION OF SYMBOLS 10 ... Electric steering device 12 ... Motor 14 ... Motor drive circuit 16 ... Rear wheel 18 ... Actuator 20 ... Current source 22 ... Sub power supply 24 ... Rapid steering discrimination | determination part 26 ... Control part 27 ... Main power supply 36 ... Electric power supply path 44 ... Current Limit instruction unit 46 ... Supply current calculation unit 48 ... Charge / discharge instruction unit 50 ... Operation stop instruction unit

Claims (5)

An electric steering device that applies assist force to a rear toe control of a vehicle using a motor as a drive source,
A current source having a boosting function capable of limiting the output current value to a predetermined value and boosting the power supply voltage for output in the middle of the power supply path between the main power supply and the drive circuit for supplying drive power to the motor When,
A sub-power supply capable of storing the output power of the current source and supplying the output power to the drive circuit ;
And means for detecting a rapid steering by luck rolling person,
A control unit ,
The current source is constituted by a DC-DC converter including a capacitor,
When the next rapid steering is detected within a predetermined time after the first rapid steering by the driver is detected, the control unit determines the drive power in the first rapid steering and the next rapid steering. An electric steering apparatus that controls the current source and the sub-power supply so that the drive power is as equal as possible . The electric steering device according to claim 1,
Based on the detection of the rapid steering of the first, and the assist amount of the first with respect to the rear toe control, based on the detection of the next rapid steering, the next assist amount for the rear toe control and wherein the equivalent absolute value Electric steering device. The electric steering device according to claim 1 or 2,
The electric steering apparatus according to claim 1, wherein when the charging state of the sub power source is equal to or less than a predetermined value, the application of assist force to the rear toe control is stopped. The electric steering apparatus according to any one of claims 1 to 3,
The means for detecting the rapid steering detects the rapid steering when the steering speed of the vehicle steering is equal to or higher than a preset threshold value, and detects the rapid steering detected after the predetermined time has passed. An electric steering apparatus characterized by detecting as steering. The electric steering apparatus according to any one of claims 1 to 3,
The electric steering apparatus according to claim 1, wherein at least the first rapid steering detection by the means for detecting the rapid steering is performed based on an obstacle detection.

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