JP2006253400A - Electromagnetic actuator controller and controller of vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic actuator controller which can correctly estimate an air gap by eliminating a search coil from an electromagnetic actuator. <P>SOLUTION: The electromagnetic actuator controller is provided with a current detecting means for detecting exciting current flowing in an exciting coil; a first control means for applying a PWM driving signal of a first duty ratio to a first switch means for first prescribed time, and applying a PWM driving signal for turning off a first switch to the first switch means; a current integration value calculating means for integrating exciting current detected by the current detecting means, and calculating a current integration value until second prescribed time elapses after the first switch is turned off; an air gap conversion map storing a corresponding relation of the respective current integration values and air gap length; and an air gap conversion means for converting the air gap into air gap length corresponding to the current integration value calculated by the current integration value calculating means by referring to the air gap conversion map. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an air gap length estimation of an electromagnetic actuator used in a torque transmission mechanism of an electronically controlled four-wheel drive vehicle or the like.

  For example, a torque transmission mechanism or the like such as an electronically controlled four-wheel drive vehicle includes a pair of left and right planetary gear sets and a pair of brake mechanisms for variably controlling the torque of a sun gear connected to each planetary gear set. Each brake mechanism includes a wet multi-plate brake and an electromagnetic actuator that operates the multi-plate brake.

  The electromagnetic actuator is provided in a cylindrical inner space, and is arranged such that a core (yoke) made of a magnetic material and a core and a cylindrical inner space are opposed to each other with a predetermined air gap in the axial direction. The armature is made of a material, an exciting coil inserted into an annular space between the core and the armature, a piston connected to the armature, and the like.

  When a current is applied to the exciting coil, a magnetic path is formed in the magnetic circuit composed of the core, the armature, and the air gap, and an electromagnetic force is generated in the air gap between the core and the armature. This electromagnetic force attracts the armature to the core to generate thrust. Due to this thrust, the piston integrally connected to the armature presses the multi-plate brake, and brake torque is generated by the frictional force generated in the multi-plate brake. The torque of the axle connected to the multi-plate brake is controlled by this brake torque.

  The ECU equipped with the microcomputer calculates the target current value to be passed through the left and right electromagnetic solenoids in order to generate the braking torque corresponding to the running state such as the turning direction and steering force or steering angle of the vehicle. Is controlled so that the exciting currents flowing through the respective target current values match each other, and the output torque to the left and right rear axles is variably controlled.

  In order to converge the excitation current value flowing through the excitation coil to the target current value at high speed, a target current value corresponding to the brake torque corresponding to the running state of the vehicle is calculated by the ECU. The ECU performs PWM control according to the difference between the target current value and the actual current flowing through the exciting coil, and supplies the PWM drive signal to the control terminal of the switching element.

  The switching element is provided in series with the exciting coil between the battery power source and the ground, and is turned on / off according to the high / low of the PWM drive signal applied to the control terminal, and the current is controlled by the exciting coil.

  A current return diode (flywheel diode) is provided in parallel with the excitation coil. When the switching element is turned off, the current return diode is turned on by the counter electromotive force generated in the excitation coil, and current reflux is passed through the excitation coil. To smooth.

  The actual current flowing through the exciting coil is detected, the actual current is compared with the target current by the PID calculation means, and PWM control is performed so that the actual current matches the target current value.

  In this way, the pulse width of the PWM drive signal applied to the switching element is controlled so that the current value of the exciting coil converges to the target current value at high speed.

  On the other hand, the air gap between the core and the armature fluctuates due to wear due to the frictional force of the multi-plate brake, and the thrust increases when the air gap narrows. As described above, a magnetic flux is generated in the magnetic flux circuit when a current flows through the exciting coil. Since the thrust applied to the air gap is determined by the magnetic flux, it is necessary to accurately control this thrust.

There exists patent document 1 as a prior art document for controlling thrust accurately. In Patent Document 1, a search coil is disposed in a magnetic path through which a magnetic flux passes, an actual current having a pulse waveform is caused to flow through an exciting coil, and an electromotive force generated in the search coil due to a change in the magnetic flux generated in the magnetic path of the magnetic circuit. It is disclosed that measurement is performed, magnetic flux is calculated, and thrust is calculated based on the magnetic flux of the calculation result, the air gap cross-sectional area, and the permeability of the core and the like.
JP 2002-303660 A

  However, in Patent Document 1, since the magnetic flux is detected using the search coil as described above, there is a problem that the cost of parts related to the search coil increases. In addition, since the electromotive force generated in the search coil has a small number of turns with respect to the exciting coil, a large magnetic energy cannot be output.

  As a result, the electromotive force generated in the search coil varies due to the influence of spike noise caused by radio waves from a radio or mobile phone used in the vehicle. When the search coil output electromotive force is integrated, the spike noise value etc. in the electromotive force are also integrated, so that the magnetic flux value calculated from the integrated value changes greatly, resulting in a large error in the estimated thrust value. there were.

  In addition, the formation of magnetic flux in the exciting coil has variations due to variations in the shapes of the yoke and the armature constituting the magnetic flux circuit. Furthermore, when the air gap length changes, the magnetic resistance related to the air gap of the magnetic circuit changes and the magnetic flux formation of the magnetic circuit also changes greatly, and the search coil cannot be made the optimal layout for magnetic flux detection. There was a point.

  As described above, the method of estimating the thrust by calculating the magnetic flux of the magnetic circuit has a problem that the estimation error becomes large.

  Therefore, an object of the present invention is to reduce the cost of the electromagnetic actuator by eliminating the search coil, and to perform an accurate torque control by estimating the air gap instead of detecting the magnetic flux. And a vehicle control device.

  According to the first aspect of the present invention, the core and the armature that face each other through the air gap, the first switch means that is turned on / off based on the PWM drive signal, the first switch means are connected in series, and An exciting coil for generating magnetic flux in the core and the armature, and connected in parallel with the exciting coil, and when the first switch means is turned off, it is turned on by electromotive force generated at both ends of the exciting coil, and the first An electromagnetic actuator control apparatus for controlling an electromagnetic actuator having a second switch means that is turned off when the switch means is on, a current detection means for detecting a current flowing through the exciting coil, and a first duty ratio After applying a PWM drive signal to the first switch means for a first fixed time, the first switch means is turned off. First control means for applying a PWM drive signal to the first switch means and detected by the current detection means until a second fixed time has elapsed after the first switch means is turned off. Referring to the air gap conversion map, the current integrated value calculating means for calculating the current integrated value by integrating the current, the air gap conversion map storing the correspondence relationship between each current integrated value and the air gap length, and the current gap There is provided an electromagnetic actuator control device comprising air gap conversion means for converting to an air gap length corresponding to the current integral value calculated by the integral value calculation means.

  According to the electromagnetic actuator control device of the first aspect, each current integrated value is calculated based on the one-to-one correspondence between the air gap and the current integrated value due to the fact that the current integrated value increases as the air gap length decreases. The correspondence relationship of the air gap length is stored in the air gap conversion map.

  When a PWM drive signal for turning off the first switch means is applied after the PWM drive signal having the first duty ratio is applied to the first switch means for a first fixed time, an electromotive force is applied to the exciting coil. Occurs, the second switch means is turned on, and a return current flows through the exciting coil.

  The current integrated value calculating means integrates the reflux current detected by the current detecting means to calculate a current integrated value. The air gap converting means converts the air gap length corresponding to the current integrated value calculated by the current integrated value calculating means with reference to the air gap conversion map. Thus, the air gap can be estimated based on the current integration value without detecting the magnetic flux by the search coil.

  According to a second aspect of the present invention, the apparatus further comprises temperature detecting means for detecting the temperature of the exciting coil, and the air gap conversion map includes the current integrated value and the air gap length at each temperature of the exciting coil. The air gap converting means corresponds to the temperature detected by the temperature detecting means and the current integrated value calculated by the current integrated value calculating means with reference to the air gap conversion map. The electromagnetic actuator control device according to claim 1, wherein the electromagnetic actuator control device converts the air gap length.

  According to the electromagnetic actuator control apparatus of the second aspect, since the current integral value depends on the temperature of the exciting coil, the temperature detecting means detects the temperature of the exciting coil, and the air gap converting means Referring to the temperature detected by the temperature detecting means and the air gap corresponding to the current integrated value calculated by the current integrated value calculating means.

  According to a third aspect of the invention, there is provided the second control means for applying the PWM drive signal having the second duty ratio to the first switch means for a third fixed time, and the temperature detecting means A resistance value of the exciting coil is detected based on the exciting current detected by the current detecting means when the third constant time has elapsed and the second duty ratio, and the exciting value is determined based on the resistance value. The electromagnetic actuator control device according to claim 2, wherein the temperature of the coil is detected.

  According to the electromagnetic actuator control device of the third aspect, the temperature of the exciting coil is detected from the relationship between the temperature of the exciting coil and the resistance.

  According to a fourth aspect of the present invention, the second constant time includes a current flowing through the excitation coil at all assumed air gaps and temperatures of the excitation coil when the second constant time has elapsed. 3. The electromagnetic actuator control device according to claim 1, wherein the time is zero.

  According to the electromagnetic actuator of the fourth aspect, when the second constant time has elapsed, the current of the exciting coil is 0, so that the current integrated value becomes large.

  According to the fifth aspect of the present invention, the core and the armature that are opposed via the air gap, the first switch means that is turned on / off based on the PWM drive signal, and the first switch means are connected in series, An exciting coil for generating magnetic flux in the core and the armature, and connected in parallel with the exciting coil, and when the first switch means is turned off, it is turned on by electromotive force generated at both ends of the exciting coil, and the first A control apparatus for a vehicle including an electromagnetic actuator having a second switch means that is turned off when one switch means is on, a current detection means for detecting a current flowing through the exciting coil, and a first duty ratio A PWM drive for turning off the first switch means after applying a PWM drive signal to the first switch means for a first fixed time. A first control means for applying a signal to the first switch means, and integrating the current detected by the current detection means until a second fixed time has elapsed since the first switch means was turned off. Current integrated value calculating means for calculating the current integrated value, an air gap conversion map for storing the correspondence between each current integrated value and the air gap length, and the current integrated value calculating means with reference to the air gap conversion map. An air gap conversion means for converting to an air gap length corresponding to the current integrated value calculated by the above, a target control current conversion map for storing a correspondence relationship between each air gap length and each driving torque and the target control current value, and Referring to the target control current conversion map, the target corresponding to the driving torque according to the running state of the vehicle and the air gap length converted by the air gap converting means A target control current value calculating means for calculating a control current value; and a PID calculating means for controlling the duty ratio of the PWM drive signal so that the current detected by the current detecting means matches the target control current value. There is provided a vehicle control apparatus characterized by the above.

  According to the vehicle control device of claim 5, the search coil is removed from the electromagnetic actuator, the air gap is estimated based on the current integrated value, and the target control current value corresponding to the target transmission torque is calculated from the air gap estimated value. Is calculated.

  According to the first aspect of the invention, since the search coil is eliminated from the electromagnetic actuator, the cost of the electromagnetic actuator is reduced. Further, since the current flowing through the exciting coil having a large number of turns and a large magnetic energy is integrated, the integrated current value is hardly affected by noise, and the air gap can be estimated accurately.

  According to the second aspect of the present invention, since the current integrated value depends on the temperature of the exciting coil, the temperature of the exciting coil is detected, and the air gap length is estimated based on the temperature of the exciting coil and the current integrated value. The air gap can be estimated more accurately.

  According to the third aspect of the present invention, since the temperature of the exciting coil is detected from the resistance value of the exciting coil, the temperature of the exciting coil can be detected without any extra cost.

  According to the fourth aspect of the present invention, when the second fixed time has elapsed, the current of the exciting coil is 0, so that the current integrated value becomes large, and the difference in the current integrated value due to the difference in the air gap is The air gap can be accurately estimated.

  According to the invention described in claim 5, since the search coil is eliminated from the electromagnetic actuator, the cost of the electromagnetic actuator is reduced. Further, since the current flowing through the exciting coil having a large number of turns and a large magnetic energy is integrated, the integrated current value is hardly affected by noise, and the air gap can be estimated with high accuracy. As a result, the drive torque can be accurately controlled.

  FIG. 1 is a diagram showing a schematic diagram of a power transmission device for a four-wheel drive vehicle based on a front engine / front drive (FF) vehicle to which the magnetic flux detection device of the present invention can be applied.

  As shown in FIG. 1, the power transmission system includes a front differential device 6 in which power from an engine 2 disposed in front of the vehicle is transmitted from an output shaft 4a of a transmission 4, and power from the front differential device 6 is propeller shaft. 8 mainly includes a speed increasing device (transmission device) 10 transmitted through 8, a rear differential device 12 to which power from the speed increasing device 10 is transmitted, and an ECU 13 for performing vehicle running control and the like.

  The front differential device 6 has a conventionally known structure, and the power from the output shaft 4a of the transmission 4 is transmitted to the left and right front wheel drive shafts 20 and 22 via the plurality of gears 14 and the output shafts 16 and 18 in the differential case 6a. By transmitting, each front wheel is driven.

  As will be described later, the rear differential device 12 includes a pair of planetary gear sets and a pair of electromagnetic actuators for controlling the fastening of a multi-plate brake mechanism (multi-plate clutch mechanism), and controls the electromagnetic actuator. By transmitting power to the left and right rear wheel drive shafts 24 and 26, the rear wheels are driven.

  FIG. 2 is a sectional view of the speed increasing device (transmission device) 10 and the rear differential device 12 disposed on the downstream side of the speed increasing device 10. The speed increasing device 10 includes an input shaft 30 rotatably mounted in a casing 28 and an output shaft (hypoid pinion shaft) 32.

  The speed increasing device 10 further includes an oil pump subassembly 34, a planetary carrier subassembly 38, a direct coupling clutch subassembly 40, and a speed change brake 42.

  The rear differential device 12 provided on the downstream side of the speed increasing device 10 has a hypoid pinion gear 44 formed at the tip of the hypoid pinion shaft 32.

  The hypoid pinion gear 44 meshes with the hypoid ring gear 48, and the power from the hypoid ring gear 48 is input to the ring gears of the planetary gear sets 50A and 50B provided on the left and right.

  The sun gears of the planetary gear sets 50A and 50B are rotatably mounted around the left rear axle 24 and the right rear axle 26. The planetary carriers of the planetary gear sets 50A and 50B are fixed to the left rear axle 24 and the right rear axle 26. A planet gear carried on the planetary carrier meshes with the sun gear and the ring gear.

  The left and right planetary gear sets 50A and 50B are coupled to a brake mechanism 51 provided for variably controlling the torque of the sun gear. The brake mechanism 51 includes a wet multi-plate brake 52 and an electromagnetic actuator 56 that operates the multi-plate brake 52.

  The brake plate of the wet multi-plate brake 52 is fixed to the casing 54, and the brake disc is fixed to the sun gears of the planetary gear sets 50A and 50B.

  The electromagnetic actuator 56 has a ring-shaped core (yoke) 58 made of a magnetic material having an annular groove, an annular excitation coil 60 inserted into the annular groove of the ring-shaped core 58, and a predetermined gap in the ring-shaped core 58. A ring-shaped armature 62 made of a magnetic material facing each other and an annular piston 64 connected to the armature 62 are configured.

  When an exciting current is passed through the exciting coil 60, the armature 62 is attracted to the core 58 by the magnetic flux generated in the magnetic circuit by the exciting current flowing through the exciting coil 60, thereby generating a thrust. Due to this thrust, the piston 64 integrally connected to the armature 62 presses the multi-plate brake 52, thereby generating a brake torque.

  As a result, the sun gears of the planetary gear sets 50A and 50B are fixed to the casing 54, respectively, and the driving force of the hypoid pinion shaft 32 passes through the ring gear, planet gear, and planet carrier of the planetary gear sets 50A and 50B. 26.

  In this way, by controlling the exciting current flowing through the exciting coil 60, the driving force of the input shaft 30 is increased in the directly connected state or with the speed increasing device 10, and is arbitrarily distributed to the left and right rear axles 24, 26. And optimal turning control can be realized.

  FIG. 3 is an excitation coil 60 and peripheral circuit diagram for controlling the excitation current flowing in the excitation coil 60 of the electromagnetic actuator 56 in FIG. As shown in FIG. 3, the electromagnetic solenoid 70 includes a switch means (first switch means) 80, a flywheel diode (second switch means) 82, and an exciting coil 60.

  The first switch means 80 is a switch for turning on / off the supply of current from the battery power supply 90 to the exciting coil 60, and according to the high level / low level of the PWM drive signal applied to the control electrode. On / off, for example, an N-channel FET (hereinafter abbreviated as FET).

  The FET 80 and the exciting coil 60 are connected in series between the battery power supply 90 and the ground. For example, the FET 80 has a drain connected to a battery power supply 90 having a predetermined positive voltage, for example, 12V, and a source connected to one end (hereinafter referred to as a first end) of the exciting coil 60. A PWM drive signal is applied to the gate.

  The flywheel diode 82 is connected in parallel with the exciting coil 60. For example, the diode 82 has an anode connected to the ground and a cathode connected to the first end of the exciting coil 60.

  When the FET 80 is turned off, the flywheel diode 82 is forward-biased by the back electromotive force generated at both ends of the exciting coil 60 and is turned on to flow a reflux current a through the exciting coil 60 as shown in FIG. The flywheel diode 82 is reverse biased and turned off when the FET 80 is turned on.

  The ratio of the high level time of the PWM drive signal to a certain clock cycle is called the duty ratio. When the PWM drive signal is at a high level, the FET 80 is turned on, an exciting current flows through the exciting coil 60, and the exciting current corresponding to the duty ratio% increases. Further, when the PWM drive signal is at a low level, the FET 80 is turned off, back electromotive force is generated at both ends of the exciting coil 60, and the return current a flows. On the other hand, when the duty ratio becomes 0, it decreases until the return current a becomes 0.

  The exciting coil 60 has a first end connected to the source of the FET 80 and the other end (hereinafter referred to as a second end) connected to the ground via a resistor 260 provided in a current detecting means 122 described later. A current flows from the battery power supply 90 to the ground through the FET 80, the exciting coil 60 and the resistor 260. Thus, the search coil is eliminated from the electromagnetic actuator 56.

  The ECU 13 performs control for torque distribution according to the traveling state of the vehicle such as the turning direction, the steering angle, the throttle opening degree, and the vehicle speed. The ECU 13 executes a program that functions as the electromagnetic actuator control means 100 that controls the electromagnetic actuator 56 so that the brake torque generated by the electromagnetic actuator 56 is optimized in accordance with the traveling state.

  FIG. 4 is a functional block diagram of the electromagnetic actuator control means 100 according to the embodiment of the present invention. As shown in FIG. 4, the electromagnetic actuator control means 100 includes an air gap length estimation means 110, a target transmission torque calculation means 112, a target control current value calculation means 114, a PID calculation means 116, a selection means 118, PWM drive signal generation means 120 and current detection means 122 are provided.

  FIG. 5 is a diagram showing the relationship between the return current and the air gap, and shows the return current in each air gap when the temperature of the exciting coil 60 is constant. Here, as an example, the return current in the air gap lengths AG1, AG2, AG3 (AG1> AG2> AG3) is shown.

  As shown in FIG. 5, as the air gap becomes smaller, the magnetic resistance of the magnetic circuit becomes smaller and the formed magnetic flux becomes larger. Therefore, the back electromotive force generated at both ends of the exciting coil 60 also increases, the return current increases, and the time until the return current becomes 0 becomes longer. As a result, the return current after the FET 80 is turned off is increased. The integrated value (current integrated value) of the reflux current increases until becomes zero.

  For example, for each air gap AGi (i = 1, 2, 3), the return current becomes 0 from the time when the PWM drive signal becomes low level, for example, from time t0 when a pulse with a predetermined duty becomes low level. The time (ti-t0) (i = 1, 2, 3) until time t1, t2, t3 becomes (t1-t0) <(t2-t0) <(t3-t0), and the current integrated value Si (i = 1, 2, 3) is S1 <S2 <S3. Thereby, it turns out that there is a one-to-one relationship between the air gap and the current integration value.

  FIG. 6 is a diagram showing the relationship between the return current and the temperature of the excitation coil 60, and shows the return current at each temperature of the excitation coil 60 when the air gap is constant. Here, the reflux current is shown when the temperature of the exciting coil 60 is low and when the temperature of the exciting coil 60 is high.

  As shown in FIG. 6, when the temperature of the exciting coil 60 is lowered, the resistance of the exciting coil 60 is decreased and a large amount of current flows. Conversely, when the temperature of the exciting coil 60 is increased, the resistance of the exciting coil 60 is increased. Less current flows. Thus, it can be seen that the current integration value depends on the temperature of the exciting coil 60.

  Therefore, when the temperature and current integration value of the exciting coil 60 are known, the air gap length in the exciting coil 60 can be estimated. That is, the current integrated value at each air gap is obtained in advance by experiment at each temperature of the exciting coil 60, and the air gap that matches the known current integrated value at the known temperature of the exciting coil 60 is obtained. The air gap length can be estimated by obtaining the length.

  The air gap length estimation means 110 is a means for estimating the air gap length from the temperature of the exciting coil 60 and the current integrated value.

  FIG. 7 is a functional block diagram of the air gap length estimation means 110 in FIG. As shown in FIG. 7, the air gap length estimation unit 110 includes a main control unit 150, a resistance detection unit 152, a current integral value calculation unit 154, an air gap length calculation unit 156, and a storage unit 158.

  The main control means 150 performs the following control for estimating the air gap length.

  (1) It is determined whether or not the air gap estimation is currently possible according to the traveling state of the vehicle. The case where the air gap estimation is possible is a case where it is determined that the control of the electromagnetic actuator 56 is not necessary based on the traveling state of the vehicle.

  (2) If the air gap estimation is feasible, control for calculating the resistance for detecting the temperature of the exciting coil 60, that is, a PWM drive signal having a constant duty ratio (second duty ratio) is supplied to the FET 80. After the excitation current is stabilized by the PWM drive signal and the excitation current is stabilized, for example, after a certain time (third constant time) has elapsed since the output of the PWM drive signal is started, the resistance detection unit An instruction to detect resistance is given to 152.

  At this time, if the duty ratio is large, the excitation current becomes large, and a large brake torque is generated in the electromagnetic actuator 56. It is dangerous to operate incorrectly when the vehicle is running, so a small value is good. Further, if the duty ratio is too small, for example, if it is 5% or less, the excitation current value and the duty ratio are not linear and cannot be used. Therefore, in this embodiment, the duty value is set to 25% as an example.

  (3) When the resistance detection unit 152 finishes detecting the temperature, after performing control for calculating the current integral value, that is, as described later, the level of the PWM drive signal is set to the low level, and the current integral value calculation unit Instruct 154 to calculate the current integral value.

  (4) When the current integration unit 154 finishes calculating the current integration value, it instructs the air gap length calculation unit 156 to calculate the air gap length.

  The main control means 150 may be controlled so that the current integrated value is calculated independently of the resistance detection. That is, control is performed so that a PWM drive signal having the same or different duty ratio (first duty ratio) as that of the PWM drive signal for resistance detection is output for a certain time (first time), and then to the resistance detection means 152. It is also possible to control so as to calculate the current integral value by skipping the resistance detection instruction.

  FIG. 8 is a time chart showing resistance detection. When the resistance detection unit 152 receives a resistance detection instruction from the main control unit 150, the resistance detection unit 152 calculates the resistance of the excitation coil 60 from the excitation current flowing in the excitation coil 60.

  As shown in FIG. 8, when a PWM drive pulse with a duty ratio of 25% is applied to the gate of the FET 80 and a predetermined time Tr elapses, the excitation current is stabilized. At this time, assuming that the power supply voltage VB of the battery power supply 90, the voltage VC applied to both ends of the exciting coil 60, and the duty ratio D of the PWM drive signal D = (25%), the voltage VC is estimated by the following equation (1). .

Voltage VC = VB × D / 100 (1)
Here, it is assumed that other resistances related to the excitation current, such as the on-resistance of the FET 80, are sufficiently smaller than the resistance value of the excitation coil 60.

  From this, the resistance R of the exciting coil 60 is calculated | required by following Formula (2).

Resistance R = Voltage VC / Excitation current I (2)
Even after the excitation current is stabilized, the excitation current value I in the equation (2) fluctuates up and down around the average value due to the PWM drive signal. As shown in FIG. The current is averaged.

  When the current integrated value calculating means 154 receives an instruction for calculating the current integrated value from the main control means 150, the current integrated value calculating means 154 integrates the return current detected by the current detecting means 122 for a certain period of time, and stores the current integrated value in the storage means 158. .

  FIG. 9 is a time chart showing calculation of the current integral value. Since the time until the return current becomes 0 differs for each air gap (AGi (i = 1, 2, 3)), as shown in FIG. 9, the fixed time (second fixed time) is assumed. The time Ts when the return current becomes 0 at all air gaps and temperatures.

  Time t0 is the time when the PWM drive signal becomes low level, and time t1 is the time when Ts = (t1−t0). As a result, when the second constant time Ts has elapsed, since the return current is 0, the current integrated value is increased.

  Further, as described above, the excitation current at time t0 may not be based on the PWM drive signal at the time of resistance measurement. The current value to be integrated may be averaged by the current detection unit 122 as in the present embodiment, or may be a current value before being averaged.

  The air gap length calculation unit 156 includes a temperature conversion map 200, a temperature conversion unit 202, an air gap conversion map 204, and an air gap conversion unit 206.

  FIG. 10 is a diagram showing the relationship between temperature and resistance, with the horizontal axis representing the resistance R of the exciting coil 60 and the vertical axis representing the temperature of the exciting coil 60. As shown in FIG. 10, as the temperature increases, for example, the resistance R under the same conditions as the resistance detection described above increases. The temperature conversion map 200 is calculated by applying the excitation current of the excitation coil 60 measured at each temperature of the excitation coil 60 to the equations (1) and (2) in an arbitrary air gap length by an experiment of the electromagnetic actuator 56. The correspondence relationship between the resistance value and the temperature is stored in advance.

  The temperature conversion unit 202 searches the temperature conversion map 200 from the resistance R of the exciting coil 60 detected by the resistance detection unit 152, converts it to a corresponding temperature, and stores this temperature in the storage unit 158. The resistance detection unit 152, the temperature conversion map 200, and the temperature conversion unit 202 constitute a temperature detection unit that detects the temperature of the exciting coil 60.

  The temperature detecting means does not detect the temperature from the exciting current but detects the oil temperature supplied to the electromagnetic brake for cooling, so that the oil temperature substantially coincides with the temperature of the exciting coil 60. The oil temperature may be estimated and the temperature of the exciting coil 60 may be used.

  In the air gap conversion map 204, the corresponding air gap length is stored in advance for the combination of the current integrated value and the temperature. The air gap conversion map 204 forms each air gap by an experiment of the electromagnetic actuator 56, for example, an annular shim having a thickness corresponding to the air gap is sandwiched between the core 58 of the electromagnetic actuator 56 and the armature 62. The exciting coil 60 is set to each temperature, and the same condition as in the case of the current integration calculation described above, that is, a PWM drive signal with a constant duty ratio (first duty ratio) is applied to the FET 80 for a fixed time (first fixed time). The current integration value is calculated by integrating the current for a second fixed time after the voltage is applied.

  The air gap conversion means 206 obtains the air gap length corresponding to the combination of the temperature and current integral values from the temperature and current integral values stored in the storage means 158 with reference to the air gap conversion map 204, and the storage means Store in 158.

  4 is output from a turning direction, a steering angle output from a steering angle sensor (not shown), a throttle opening output from a throttle opening sensor (not shown), a vehicle speed sensor (not shown), and the like. A target transmission torque to be distributed to the left and right rear wheel axles 24 and 26 is calculated according to the running state of the vehicle.

  FIG. 11 is a functional block diagram of the target control current value calculation means 114. As shown in FIG. 11, the target control current value calculation unit 114 includes a target control current conversion map 250 and a target control current conversion unit 252. In the target control current conversion map 250, target control current values corresponding to combinations of target transmission torques and air gaps are stored in advance. This map 250 is created by obtaining the brake torque (target transmission torque) by the thrust with respect to the target control current value in each air gap by the experiment of the electromagnetic actuator 56.

  The target control current conversion unit 252 responds by referring to the target control current conversion map 250 from the combination of the air gap length stored in the storage unit 158 and the target transmission torque calculated by the target transmission torque calculation unit 112. Convert to target control current value.

  4 determines the duty ratio of the PWM drive signal so that the actual current value detected by the current detection means 122 converges to the target current value. That is, according to the difference between the actual current detected by the current detection means 122 and the target current value, if the target value is larger than the actual current, the target value is smaller than the actual current so that the actual current increases. If so, the duty ratio is determined so that the actual current is maintained if the target value matches the actual current so that the actual current decreases.

  The selection unit 118 selects one of the effective duty ratios output from the air gap length estimation unit 110 and the PID calculation unit 116 and outputs the selected duty ratio to the PWM drive signal generation unit 120.

  The PWM drive signal generation unit 120 outputs the PWM drive signal with the duty ratio output from the selection unit 118 to the electromagnetic solenoid 70.

  As illustrated in FIG. 3, the current detection unit 122 includes a resistor 260, an operational amplifier 262, an averaging unit 264, and an A / D converter 266. One end of the resistor 260 is connected to the exciting coil 60 and the negative terminal of the operational amplifier 262, and the other end is grounded and connected to the positive terminal of the operational amplifier 262.

  The operational amplifier 262 detects the value of the current flowing through the exciting coil 60 by calculating the voltage across the resistor 260. The averaging means 264 averages the current value (analog) output from the operational amplifier 262 using, for example, a CR filter. The A / D converter 266 converts the analog voltage value output from the averaging means 264 into a digital voltage value at a constant sampling period.

  FIG. 12 is a flowchart showing a driving torque control method. FIG. 13 is a flowchart of resistance estimation in FIG. FIG. 14 is a flowchart of current integration in FIG. FIG. 15 is a flowchart of air gap estimation in FIG. FIG. 16 is a flowchart of the normal control in FIG. Hereinafter, the drive torque control method will be described with reference to these drawings.

  In step S2 in FIG. 12, the main control means 150 determines whether or not normal control is necessary based on the running state of the vehicle. If normal control is not required, the process proceeds to step S4. If normal control is necessary, the process proceeds to step S20.

  In step S4, it is determined whether or not the resistance estimation is finished. If the resistance estimation is not completed, the process proceeds to step S6. If the resistance estimation has been completed, the process proceeds to step S8.

  In step S6, resistance estimation shown in FIG. 13 is performed. In step S50 in FIG. 13, the main control means 150 applies a PWM drive signal with a resistance detection duty ratio of 25% to the FET 80 through the selection means 118 and the PWM drive signal generation means 120 as shown in FIG.

  In step S52, the main control means 150 determines whether or not a predetermined time Tr has elapsed since the output of the PWM drive signal for resistance estimation was started. If the predetermined time Tr has elapsed, the process proceeds to step S54. If the predetermined time has not elapsed, step S52 is repeatedly executed.

  In step S <b> 54, the resistance detection unit 152 reads the averaged excitation current output from the current detection unit 122. At this time, since the constant time Tr has elapsed, the excitation current is stabilized, and the average value I thereof is a constant current value.

  In step S <b> 56, the resistance detection unit 152 acquires the battery voltage VB of the battery power supply 90. In step S58, the resistance detection means 152 calculates the resistance R of the excitation coil 60 by substituting VB, resistance calculation duty D (25%), and excitation current I into equations (1) and (2). 12 proceeds to step S8.

  In step S8, the main control means 150 determines whether or not the current integration has been completed. If current integration has not ended, the process proceeds to step S10. If the current integration has been completed, the process proceeds to step S12. In step S10, the process proceeds to step S100 in FIG.

  In step S100, the main control means 150 determines whether or not the current I of the exciting coil 60 is zero. If the current I of the exciting coil 60 is 0, the current integration is performed independently of the resistance detection, and the process proceeds to step S102. If the current I of the exciting coil 60 is not 0, the current integration immediately after resistance detection is performed, and therefore the process proceeds to step S106.

  In step S102, the main control means 150 controls to apply the PWM drive signal for calculating the current integral value to the FET 80 as shown in FIG. In step S104, the main control means 150 determines whether or not a certain time (first certain time) has elapsed for the excitation current I to stabilize. If the fixed time has elapsed, the process proceeds to step S106. If the predetermined time has not elapsed, step S104 is looped.

  In step S106, the current integrated value calculation means 154 stores the initial value 0 in the current integrated value storage area. In step S108, the current integration value calculation unit 154 determines whether or not a fixed time (second fixed time) Ts has elapsed since the start of integration.

  If the predetermined time Ts has not elapsed, the process proceeds to step S110. If the fixed time Ts has elapsed, the process ends and returns to step S14. In step S110, the current integration value calculation unit 154 performs, for example, current integration from the integration value stored in the storage area of the current output by the current detection unit 122, the sampling period, and the current integration value to the current time. Thereafter, the process proceeds to step S108.

  In step S14, air gap estimation shown in FIG. 15 is performed. In step S150 in FIG. 15, the temperature conversion means 202 calculates a corresponding temperature by referring to the temperature conversion map 200 from the resistance value calculated in step S6.

  In step S152, the air gap conversion means 206 calculates a corresponding air gap length from the current integrated value calculated in step S10 and the temperature calculated in step S150 with reference to the air gap conversion map 204.

  In step S20, the control current shown in FIG. 16 is calculated. In step S200 in FIG. 16, the target transmission torque calculating means 112 calculates the target transmission torque to be distributed to the left and right rear axles 24 and 26 according to the running state of the vehicle. Then, the target control current conversion means 252 in the target control current value calculation means 114 is a target control current value calculation means based on the air gap length calculated in step S14 and the target transmission torque calculated by the target transmission torque calculation means 112. The target control current is calculated with reference to the target control current conversion map 250 in 114. The PID calculation unit 116 performs PWM control so that the excitation current detected by the current detection unit 122 matches the target control current. Thereby, a target transmission torque is generated.

  As described above, according to the present embodiment, since the search coil is eliminated from the electromagnetic solenoid 70, the search coil and the circuit for detecting the electromotive force of the search coil are not required, and the cost of the electromagnetic actuator 56 is reduced. .

  Further, since the current flowing through the exciting coil 60 having a large number of turns and a large magnetic energy is integrated, the integrated current value is hardly affected by noise, and the air gap can be estimated accurately.

  Further, since the current integration value depends on the temperature of the exciting coil 60, the temperature of the exciting coil is detected, and the air gap length is estimated based on the temperature of the exciting coil 60 and the current integrated value. The gap can be estimated.

  Moreover, since the temperature of the exciting coil 60 is detected from the resistance value of the exciting coil 60, the temperature of the exciting coil can be detected without extra cost. Furthermore, since the current integration value is integrated with respect to the assumed temperature and air gap until the time when the current integration value becomes 0, the current integration value increases, and the air gap can be estimated more accurately.

It is the schematic which shows the power transmission system of a four-wheel drive vehicle. It is sectional drawing of a speed increasing apparatus (transmission apparatus) and a rear differential apparatus. It is a figure which shows an electromagnetic solenoid and a peripheral circuit. It is a functional block diagram of an electromagnetic actuator control means. It is a figure which shows the relationship between a recirculation | reflux current and an air gap. It is a figure which shows the relationship between a reflux current and the temperature of an exciting coil. It is a functional block diagram of the air gap length estimation means in FIG. It is a time chart which shows resistance detection. It is a time chart which shows electric current integral value calculation. It is a figure which shows the relationship between temperature and resistance. FIG. 5 is a functional block diagram of a target control current value calculation unit in FIG. 4. It is a flowchart which shows a drive torque control method. It is a flowchart which shows resistance estimation. It is a flowchart which shows an electric current integration. It is a flowchart which shows air gap estimation. It is a flowchart which shows normal control.

Explanation of symbols

10 Speed increaser (transmission)
12 Rear differential devices 24, 26 Rear axle 30 Input shaft 32 Output shaft 50A, 50B Planetary gear set 51 Brake mechanism 52 Wet multi-plate brake 56 Electromagnetic actuator 58 Core (yoke)
60 Exciting coil 62 Armature 70 Electromagnetic solenoid 80 First switch means 82 Second switch means 100 Electromagnetic actuator control means 110 Air gap length estimation means 114 Target control current value calculation means 116 PID calculation means 122 Current detection means

Claims (5)

A core and an armature that face each other through an air gap, a first switch unit that is turned on / off based on a PWM drive signal, and a first switch unit that are connected in series to generate magnetic flux in the core and the armature An excitation coil that is connected in parallel with the excitation coil, and is turned on by an electromotive force generated at both ends of the excitation coil when the first switch means is turned off, and is turned off when the first switch means is turned on. An electromagnetic actuator control device for controlling an electromagnetic actuator having a second switch means,
Current detecting means for detecting a current flowing in the exciting coil;
After a PWM drive signal having a first duty ratio is applied to the first switch means for a first fixed time, a PWM drive signal for turning off the first switch means is applied to the first switch means. First control means to apply,
Current integrated value calculating means for calculating a current integrated value by integrating the current detected by the current detecting means until a second fixed time elapses after the first switch means is turned off;
An air gap conversion map that stores the correspondence between each current integral value and the air gap length;
Referring to the air gap conversion map, air gap conversion means for converting into an air gap length corresponding to the current integrated value calculated by the current integrated value calculation means;
An electromagnetic actuator control device comprising:   The air gap conversion map further stores a correspondence relationship between the current integration value and the air gap length at each temperature of the excitation coil, and further includes temperature detection means for detecting the temperature of the excitation coil. The gap converting means converts the air gap length corresponding to the temperature detected by the temperature detecting means and the current integrated value calculated by the current integrated value calculating means with reference to the air gap conversion map. The electromagnetic actuator control device according to claim 1.   A second control unit configured to apply a PWM drive signal having a second duty ratio to the first switch unit for a third fixed time, and the temperature detection unit detects when the third fixed time has elapsed. The resistance value of the exciting coil is detected based on the exciting current detected by the current detecting means and the second duty ratio, and the temperature of the exciting coil is detected based on the resistance value. The electromagnetic actuator control device according to claim 2.   The second constant time is a time when the current flowing through the exciting coil becomes 0 at all assumed air gaps and temperatures of the exciting coil when the second constant time has elapsed. The electromagnetic actuator control device according to claim 1 or 2. A core and an armature that face each other through an air gap, a first switch unit that is turned on / off based on a PWM drive signal, and the first switch unit are connected in series to generate a magnetic flux in the core and the armature An excitation coil that is connected in parallel with the excitation coil, and is turned on by an electromotive force generated at both ends of the excitation coil when the first switch means is turned off, and is turned off when the first switch means is turned on. A control apparatus for a vehicle including an electromagnetic actuator having a second switch means,
Current detecting means for detecting a current flowing in the exciting coil;
After a PWM drive signal having a first duty ratio is applied to the first switch means for a first fixed time, a PWM drive signal for turning off the first switch means is applied to the first switch means. First control means to apply,
Current integrated value calculating means for calculating a current integrated value by integrating the current detected by the current detecting means until a second fixed time elapses after the first switch means is turned off;
An air gap conversion map that stores the correspondence between each current integral value and the air gap length;
Referring to the air gap conversion map, air gap conversion means for converting into an air gap length corresponding to the current integrated value calculated by the current integrated value calculation means;
A target control current conversion map for storing a correspondence relationship between each air gap length and each driving torque and a target control current value;
A target control current value calculating means for calculating a target control current value corresponding to the driving torque according to the running state of the vehicle and the air gap length converted by the air gap converting means with reference to the target control current conversion map; ,
PID calculation means for controlling the duty ratio of the PWM drive signal so that the current detected by the current detection means matches the target control current value;
A vehicle control apparatus comprising:

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