JP2007292185A - Magnetic flux detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic flux detecting device for actualizing precise torque control, having a reduced size while reducing cost for an electromagnetic actuator without using a search coil. <P>SOLUTION: The magnetic flux detecting device is provided for an electromagnetic clutch which consists of a core and an armature opposed to each other via an air gap, a switching means, an exciting coil connected directly to the switching means for generating a magnetic flux in the core, the armature and the air gap, and a multiple disc clutch to be fastened thereto in accordance with the magnetic flux generated in the air gap. It comprises a current detecting means for detecting a current value for a current flowing in the exciting coil, an energization control means for turning the switching means on to increase applied voltage on the exciting coil, an induced voltage calculating means for calculating induced voltage generated in the exciting coil in accordance with the applied voltage, a resistance value relating to a passage in which a current flows, and a current value during an increase in the applied voltage detected by the current detecting means, and a magnetic flux calculating means for calculating the magnetic flux of the exciting coil with the time integration of the induced voltage. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a core and an armature that face each other through an air gap, an exciting coil that generates a magnetic flux in the core, the armature, and the air gap, a voltage applying unit that applies a voltage to the exciting coil, and a magnetic flux that is generated in the air gap. The present invention relates to a magnetic flux detection device for an electromagnetic clutch having a multi-plate clutch fastened based on the clutch. For example, the present invention relates to a magnetic flux detection device for 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 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 voltage 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 clutch, and brake torque is generated by the frictional force generated in the multi-plate clutch. The torque of the axle connected to the multi-plate clutch is controlled by this brake torque.

  The ECU equipped with the microcomputer calculates the target current value to be passed to the left and right electromagnetic solenoids in order to generate the braking torque according to the running state such as the turning direction of the vehicle and the steering force or the steering angle. 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.

  A target current value to be passed through the exciting coil corresponding to the brake torque corresponding to the running state 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 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 flowing through the exciting coil is controlled. 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 changes due to wear due to the frictional force of the multi-plate clutch, and the thrust increases when the air gap becomes narrower. 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 voltage generated in the search coil due to a change in magnetic flux generated in the magnetic path of the magnetic circuit is disclosed. It is described 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, there is a problem that the cost of parts related to the search coil increases. Further, the electromotive voltage generated in the search coil cannot output large magnetic energy because the number of turns of the search coil is smaller than the number of turns of the exciting coil. For this reason, the electromotive voltage generated in the search coil varies under the influence of spike noise caused by radio waves from a radio or mobile phone used in the vehicle, and when the output electromotive voltage of the search coil is integrated, the spike in the electromotive voltage is integrated. There is a problem that noise values and the like are also integrated, and the value of magnetic flux calculated from the integrated value changes, resulting in an error in the estimated thrust value.

  Accordingly, an object of the present invention is to provide a magnetic flux detection device that can eliminate the search coil, reduce the cost of the electromagnetic clutch, reduce the size of the device, and perform accurate torque control.

  According to the first aspect of the present invention, the core and the armature that face each other through the air gap, the exciting coil that generates magnetic flux in the core, the armature, and the air gap, and the voltage applying means that applies a voltage to the exciting coil And an electromagnetic clutch non-engagement detection device for detecting whether or not the electromagnetic clutch is in a non-engaged state, wherein the electromagnetic clutch has a multi-plate clutch that is fastened based on a magnetic flux generated in the air gap. And when the electromagnetic clutch non-engagement detecting means detects the non-engagement state of the electromagnetic clutch, the first energization control means for controlling the voltage applying means to increase the applied voltage of the exciting coil, Current detection means for detecting a current value of a current flowing through the exciting coil, the applied voltage, a resistance value associated with a path through which the current flows, and the current First induced electromotive voltage calculation means for calculating an induced electromotive voltage when the applied voltage generated in the exciting coil is increased based on the current value when the applied voltage is increased detected by the detecting means; and the voltage application Second energization control means for controlling the means to reduce the applied voltage of the exciting coil, and when the applied voltage, the resistance value associated with the path through which the current flows, and the applied voltage detected by the current detecting means are reduced. Second induced electromotive voltage calculation means for calculating an induced electromotive voltage when the applied voltage generated in the exciting coil is decreased based on the current value of the excitation coil, and when the applied voltage is increased and when the applied voltage is decreased, And a magnetic flux calculating means for integrating the induced electromotive voltages with respect to time and calculating magnetic flux of the exciting coil based on a difference value between integrated values when the applied voltage is increased and when the applied voltage is decreased. Out apparatus is provided.

  According to a second aspect of the present invention, in the first aspect of the present invention, the temperature detecting means for detecting the temperature of the exciting coil, and the resistance value is corrected based on the temperature of the exciting coil detected by the temperature detecting means. And a temperature correction unit that performs the calculation, and the induced electromotive force calculation unit calculates the induced electromotive voltage based on the resistance value corrected by the temperature correction unit. .

  According to the first aspect of the present invention, the induced electromotive voltage generated when the applied voltage is increased in the exciting coil is calculated based on the applied voltage, the resistance value related to the path through which the current flows, and the current value when the applied voltage is increased. Based on the resistance value of the path through which the current flows and the current value when the applied voltage is decreased, the induced electromotive force is generated when the applied voltage is decreased, and the magnetic flux is calculated based on the difference value between the integrated values when the applied voltage is increased and when the applied voltage is decreased. Therefore, since the magnetic flux of the exciting coil is calculated, a search coil is not necessary, and the cost of the magnetic flux detecting device can be reduced and the size of the device can be reduced. Further, the influence of the drift induced electromotive voltage can be removed, and the magnetic flux can be detected accurately.

  According to the second aspect of the present invention, since the induced electromotive voltage is calculated by detecting the temperature of the exciting coil and correcting the resistance value, the induced electromotive voltage can be calculated accurately, and the accuracy of the detected magnetic flux is increased. Can be improved.

  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 an electromagnetic actuator as a pair of electromagnetic clutches for controlling the fastening of a multi-plate brake mechanism (multi-plate clutch mechanism). Each rear wheel is driven by controlling the actuator to transmit power to the left and right rear wheel drive shafts 24 and 26.

  FIG. 2 is a cross-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 (electromagnetic clutch) 51 includes a multi-plate brake 52 and an electromagnetic actuator 56 that operates the multi-plate brake 52.

  The brake plate of the 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 a voltage is applied to the excitation coil 60, an excitation current flows through the excitation coil 60. The armature 62 is attracted to the core 58 by the magnetic flux generated in the air gap by the exciting current flowing through the exciting coil 60 to generate thrust. Due to this thrust, the piston 64 integrally connected to the armature 62 presses the multi-plate brake 52 (the electromagnetic clutch 51 is fastened), 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 a directly connected state or with the speed increasing device 10, and torque is arbitrarily applied to the left and right rear axles 24, 26. It can be distributed, and optimal turning control can be realized.

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

  The switch means (voltage applying means) 80 is a switch for turning on / off a voltage (applied voltage) applied from the battery power source 90 to the exciting coil 60 in order to apply a voltage to the exciting coil 60, and is applied to the control electrode. This switch is turned on / off in accordance with the high level / low level of the PWM drive signal. The switch means 80 and the exciting coil 60 are connected in series between a battery power source (for example, 12V power source) 90 and the ground. For example, the switch means 80 has, for example, one electrode connected to a 12V battery power supply 90 and the other electrode connected to one end (hereinafter referred to as a first end) of the exciting coil 60. A PWM drive signal is applied to the control electrode. The voltage application means includes a circuit for gradually increasing or decreasing the applied voltage of the exciting coil 60 described later.

  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 becomes high level, the switch means 80 is turned on, the excitation current increases in the excitation coil 60, and when the PWM drive signal becomes low level, the switch means 80 is turned off and the excitation corresponding to the duty ratio. Current flows. When the PWM drive signal is at a low level, the switch unit 80 is turned off, an induced electromotive voltage is generated at both ends of the exciting coil 60, and a current flows from the exciting coil 60 to the ground.

  The excitation coil 60 has a first end connected to the other electrode of the switch unit 80 and the other end (second end) connected to the ground through a resistor 260 provided in a current detection unit 122 described later. A current flows from the battery power source 90 to the ground through the switch means 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. For example, the ECU 13 executes a program for realizing 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 of the vehicle. And a peripheral circuit for detecting the current flowing through the exciting coil 60.

  FIG. 4 is a 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 a magnetic flux detection 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, and a PWM drive. A signal generation unit 120 and a current detection unit 122 are included.

  5 and 6 are diagrams showing the principle of detecting the magnetic flux Φ of the exciting coil 60. FIG. In FIG. 5, a resistance R is a circuit resistance related to a path through which a current flows from the battery power supply 90 to the ground through the electromagnetic solenoid 70, and includes a resistance of the exciting coil 60 and the like. In FIG. 6, V is a power supply voltage of the battery power supply 90, V 'is a voltage between one end of the exciting coil 60 and the ground (referred to as an applied voltage of the electromagnetic solenoid 70), I is a current flowing through the exciting coil 60, and e is an exciting coil. 60 shows the induced electromotive voltage generated at both ends of 60. In the steady state where the switch means 80 is turned on, the applied voltage V ′ becomes equal to a predetermined voltage, for example, the voltage V of the battery power supply 90, and the current I flows through the exciting coil 60. Note that the voltage application means may be controlled to gradually increase or decrease the applied voltage V ′ instead of stepwise, thereby gradually increasing or decreasing the excitation current I.

  The number of turns of the exciting coil 60 is N, the magnetic flux per turn of the exciting coil 60 is φ, the self-inductance of the exciting coil 60 is L, the magnetic flux of N turns is Φ (= Nφ), and the time derivative of the magnetic flux Φ is dΦ / dt, The time derivative of the current I is dI / dt, and the voltage of the battery power supply 90 is V.

  From Φ = Nφ = LI, Expression (1) is established.

dΦ = L × dI (1)
When the applied voltage V ′ changes, the excitation current I changes, the magnetic flux Φ changes, and the circuit shown in FIG.

V ′ = (dΦ / dt) + R × I (2)
The induced electromotive voltage e is calculated from the equation (3).

e = − (dΦ / dt) = R × IV ′ (3)
As for the magnetic flux φ, when the induced electromotive voltage of the exciting coil 60 is e, Expression (4) is established.

φ = − (1 / N) ∫edt (4)
The integration time of the induced electromotive voltage e is such that the applied voltage V ′ is constant (zero) from the time when the exciting current I is the first constant current (including zero) and the magnetic flux Φ is the first constant magnetic flux (including zero). The time until the magnetic flux Φ becomes the second constant magnetic flux (including zero). The applied voltage V ′ may be changed from zero to a predetermined voltage, for example, the power supply voltage V, or may be changed from a predetermined voltage, for example, the power supply voltage V to zero. The change may change instantaneously as in step application or may gradually change linearly.

(A) When the applied voltage V ′ is increased from zero to a predetermined voltage, for example, the power supply voltage V (applied voltage increase) In step application, a predetermined voltage, for example, the power supply voltage V is applied from the battery power supply 90 to the exciting coil 60. And the circuit shown in FIG.

V = (dΦ / dt) + R × I (5)
From the expressions (1) and (5), the expression (6) is established.

V = L × (dI / dt) + R × I (6)
Solving equation (6), equation (7) holds because the initial value of current I is zero when the applied voltage is increased.

I = V / R (1-exp (−R / L) × t) (7)
The induced electromotive force e is calculated from the equation (8).

e = − (dΦ / dt) = R × I−V (8)
As for the magnetic flux φ, when the induced electromotive voltage of the exciting coil 60 is e, Expression (9) is established.

φ = − (1 / N) ∫edt (9)
Thus, the magnetic flux φ per turn can be calculated by time-integrating the induced electromotive voltage e calculated by the equation (8) according to the equation (9). However, the integration time of the induced electromotive voltage e is such that the applied voltage V ′ when the current I is zero and the magnetic flux Φ is zero is a constant voltage from the time t1 when the applied voltage V ′ rises from zero to a predetermined voltage, for example, the power supply voltage V. (V / R) and the time until an arbitrary time t2 at which the magnetic flux Φ becomes substantially constant. The integration time (t2-t1) is calculated in advance based on the time constant L / R as shown in the equation (7). For example, as shown in FIG. 6, the absolute value (area) of the integral value S1 is the magnetic flux Φ. The integrated value of the induced electromotive voltage e is called an integrated value at the time of voltage increase.

  In the case where the applied voltage other than the step application is gradually increased, the applied voltages V ′ until the applied voltage V ′ rises to a predetermined voltage, for example, the power supply voltage V, are taken into consideration in the equations (2) and (3). Based on this, the induced electromotive voltage e is calculated from the start to the end of the increase in the applied voltage V ′. When the predetermined voltage is different from the power supply voltage V, the predetermined voltage may be substituted for V in the equations (5) to (8).

(B) When the applied voltage V ′ is reduced from a predetermined voltage, for example, the power supply voltage V to 0 (decreased applied voltage) In step application, the battery power supply 90 is not applied to the exciting coil 60 and the circuit shown in FIG. Equation (10) holds.

0 = (dΦ / dt) + R × I (10)
From equations (1) and (10), equation (11) is established.

0 = L × (dI / dt) + R × I (11)
When equation (11) is solved, when the applied voltage is decreased, equation (12) is established because the initial value of current I is V / R.

I = V / R (exp (−R / L) × t) (12)
The induced electromotive force e is calculated from the equation (13).

e = − (dΦ / dt) = R × I (13)
As for the magnetic flux φ, when the induced electromotive voltage of the exciting coil 60 is e, Expression (14) is established.

φ = − (1 / N) ∫edt (14)
Thereby, the magnetic flux φ per turn can be calculated by time-integrating the induced electromotive voltage e calculated by the equation (13) according to the equation (14). However, the integration time of the induced electromotive force e is substantially zero from time t3 when the applied voltage V ′, where the current I is constant at V / R and the magnetic flux Φ is constant, falls from V to zero, and the magnetic flux Φ. Is a time until an arbitrary time t4 when becomes substantially zero. The integration time (t4-t3) is calculated in advance based on the time constant L / R as shown in the equation (12). For example, as shown in FIG. 6, the absolute value of the area indicated by the integral value S2 is the magnetic flux Φ. The integrated value of the induced electromotive voltage e is called an integrated value at the time of voltage decrease.

  In cases other than step application, the induced voltage is generated based on the equations (2) and (3) in consideration of the applied voltage V ′ until the applied voltage V ′ falls to zero from the power supply voltage V. The voltage e is calculated. When the predetermined voltage is different from the power supply voltage V, the predetermined voltage may be substituted for V in Expression (12).

First Embodiment FIG. 7 is a functional block diagram of magnetic flux detection means 110 according to the first embodiment of the present invention. As shown in FIG. 7, the magnetic flux detection means 110 includes an energization control means 150, an actual voltage calculation means 152, an induced electromotive voltage calculation means 154, and a magnetic flux calculation means 1546.

  The energization control means 150 is a predetermined state in which the vehicle travels from the turning direction, the steering angle, the throttle opening, the vehicle speed, etc., that is, the non-engaged state of the electromagnetic clutch 51 in which the driving force distribution is not performed by the electromagnetic clutch 51, for example, Detecting whether or not the vehicle is stopped (when the wheel rotation speed is 0, the shift lever not shown is operated to P (parking) or N (neutral)) (electromagnetic clutch non-engagement detecting means) ).

  When the non-engaged state of the electromagnetic clutch 51 is detected, in order to detect the magnetic flux φ, the switch means 80 is turned off, the applied voltage V ′ is made zero, and the energization to the electromagnetic solenoid 70 is stopped. The switch means 80 is turned on and the applied voltage V ′ becomes a predetermined voltage, for example, the power supply voltage V. After the applied voltage V is applied for a certain time, the switch means 80 is turned off and the applied voltage V ′ is made zero. The PWM drive signal generation means 120 is instructed through the selection means 118 so that the energization of the electromagnetic solenoid 70 is stopped.

  The fixed time is a time until the exciting current I becomes substantially constant (= V / R), and is calculated based on the time constant L / R. Here, the high level of the PWM drive signal only needs to be a certain time or longer, and the duty ratio does not matter. The reason why the air gap measurement is performed when the electromagnetic clutch 51 is not engaged is that the current needs to flow through the exciting coil 50 for air gap measurement, which generates a magnetic flux, and thus the electromagnetic clutch 51 is engaged. Because there is a fear.

  The actual voltage calculation means 152 is the excitation detected by the current detection means 122 for the time from the time when the applied voltage V ′ starts to increase, for example, from the time t1 when the switch means 80 is turned on to the time t2 when a certain time has elapsed. The product R × I of the current I and the resistance R is calculated as an actual voltage. The resistance R is measured in advance and stored in the memory of the ECU 13.

  The induced electromotive voltage calculating means 154 calculates the induced electromotive voltage e from the expression (8) from time t1 to time t2 from the voltage V of the battery power supply 90 and the actual voltage R × I calculated by the actual voltage calculating means 152. calculate. The magnetic flux calculating means 156 integrates the induced electromotive voltage e calculated by the electromotive voltage calculating means 154 from time t1 to time t2, and calculates the magnetic flux φ from the integrated value at the time of voltage increase according to the equation (9).

  FIG. 8 is a flowchart showing an example of the magnetic flux detection method. FIG. 9 is a time chart showing an example of a magnetic flux detection method. In step S2, the switch means 80 is turned off to stop energization of the electromagnetic solenoid 70. In step S4, the switch means 80 is turned on to apply a predetermined voltage, for example, the power supply voltage V, to the electromagnetic solenoid 70. For example, as shown in FIG. 9, it is assumed that the switch means 80 is turned on at time t1. When the switch unit 80 is turned on, a current I flows from the battery power source 90 through the switch unit 80 and the exciting coil 60 to the ground.

  In step S6, the product R × I of the current I and the resistance R detected by the actual current detecting means 122 is calculated as an actual voltage. In step S8, the induced electromotive voltage e is calculated from the difference between the actual voltage R × I and the applied voltage V according to the equation (8). In step S10, the induced electromotive force e is integrated from time t1 to time t2. For example, as shown in FIG. 9, when the induced electromotive voltage e is integrated from time t1 to time t2, the integrated value indicated by reference sign S1 shown in FIG. 9 is the voltage increase integrated value. From this integrated value, the magnetic flux φ0 is calculated according to the equation (9). Thereby, the magnetic flux φ0 when the current I is a predetermined voltage / R, for example, V / R is calculated.

  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.

  The target control current value calculation means 114 searches, for example, a table storing the relationship between the magnetic flux of the excitation coil 60 and the air gap, and the magnetic flux detection means 110 causes the excitation current to be a predetermined voltage / R, for example, the power supply voltage V / R. The air gap corresponding to the magnetic flux φ0 is estimated, and the excitation current corresponding to the target transmission torque in the air gap estimated from the map storing the relationship between each transmission torque and the excitation current in each air gap is calculated. Calculated as the target control current value.

  The PID calculation means 116 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 control current value. That is, according to the difference between the actual current detected by the current detection unit 122 and the target control current value, if the target control current value is larger than the actual current, the target control current value is set so that the actual current increases. If the current is smaller than the actual current, the duty ratio is determined so that the actual current decreases, and if the target control current value matches the actual current, the actual current is maintained.

  The selection unit 118 selects one output of the magnetic flux detection unit 110 and the PID calculation unit 116 and outputs the selected output to the PWM drive signal generation unit 120. The PWM drive signal generation means 120 controls the switch means 80 based on the ON / OFF instruction of the switch means 80 from the magnetic flux detection means 110 output through the selection means 118 or the duty ratio from the PID calculation means 116. Output to electrode.

  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.

  As described above, in this embodiment, the induced electromotive voltage e is calculated from the applied voltage, current I, and resistance R when the applied voltage V ′ increases from zero to a predetermined voltage (power supply voltage V), and this is integrated. By doing so, since the magnetic flux is calculated, a search coil is not required, and it is possible to reduce the cost and size of the magnetic flux detection device and improve the accuracy of magnetic flux detection. In cases other than step application, an induced voltage is generated based on the equations (2) and (3) in consideration of the applied voltage V ′ until the applied voltage V ′ rises from zero to a predetermined voltage, for example, the power supply voltage V. e is calculated.

Second Embodiment FIG. 10 is a block diagram of a magnetic flux detection means 300 according to a second embodiment of the present invention. Components substantially the same as those in FIG. 7 are denoted by the same reference numerals. The magnetic flux detection means 300 of this embodiment calculates a magnetic flux when the applied voltage V ′ of the electromagnetic solenoid 70 is decreased from a predetermined voltage, for example, the power supply voltage V to 0. The induced electromotive voltage calculating means 302 calculates the induced electromotive voltage e from the equation (13) from time t3 to time t4 from the actual voltage R × I calculated by the actual voltage calculating means 152.

  FIG. 11 is a flowchart showing an example of a magnetic flux detection method. FIG. 12 is a time chart showing an example of a magnetic flux detection method. In step S50, the switch means 80 is turned off to stop energization of the electromagnetic solenoid 70. In step S52, the switch unit 80 is turned on to apply a predetermined voltage, for example, the power supply voltage V, to the electromagnetic solenoid 70. For example, as shown in FIG. 12, it is assumed that the switch unit 80 is turned on at time t1. When the switch unit 80 is turned on, a current I flows from the battery power source 90 through the switch unit 80 and the exciting coil 50 to the ground. After a certain time has elapsed from time t1, the current I becomes equal to V / R. In step S54, the switch means 80 is turned off to stop energization of the electromagnetic solenoid 70. For example, as shown in FIG. 12, it is assumed that energization of the electromagnetic solenoid 70 is stopped at time t3.

  In step S56, the product R × I of the current I and the resistance R detected by the actual current detecting means 122 is calculated as an actual voltage. In step S58, the induced electromotive force e is calculated from the difference between the actual voltage R × I and the applied voltage V ′ = 0 according to the equation (13). In step S60, the induced electromotive force e is integrated from time t3 to time t4. For example, as shown in FIG. 12, when the induced electromotive voltage e is integrated from time t3 to time t4, the integrated value indicated by reference sign S2 shown in FIG. The magnetic flux φ0 is calculated from the integrated value at the time of voltage reduction according to the equation (14). Thereby, the magnetic flux φ0 when the current I is a predetermined voltage / R, for example, V / R is calculated.

  As described above, in the present embodiment, the induced electromotive force e is calculated from the current I and the resistance value R when the applied voltage V ′ is decreased from V to zero, and the resultant is integrated to calculate the magnetic flux. This eliminates the need for a search coil, thereby reducing the cost and size of the magnetic flux detection device and improving the accuracy of magnetic flux detection. In cases other than step application, the induced voltage is generated based on the equations (2) and (3) in consideration of the applied voltage V ′ until the applied voltage V ′ falls to zero from the power supply voltage V. The voltage e is calculated.

Third Embodiment FIG. 13 is a block diagram of magnetic flux detection means 350 according to a third embodiment of the present invention. Components that are substantially the same as those in FIG. 7 are given the same reference numerals. The magnetic flux detection means 350 of the present embodiment uses an induced electromotive voltage when the applied voltage V ′ is increased from zero to a predetermined voltage, for example, the power supply voltage V, and the applied voltage V ′ from a predetermined voltage, for example, the power supply voltage V. The magnetic flux is calculated by combining with the induced electromotive voltage when it is reduced to zero. The induced electromotive force calculation means 352 makes the current I constant from time t1 when the applied voltage V ′ is changed from zero to a predetermined voltage, for example, the power supply voltage V, based on the actual voltage R × I calculated by the actual voltage calculation means 152. Until the time t2, the induced electromotive voltage e is calculated from the equation (8), and the applied voltage V ′ is set to a predetermined voltage, for example, from the power supply voltage V to the time t3 to the time t4 when the current becomes zero, The induced electromotive voltage e is calculated from the equation (13). The magnetic flux calculating means 354 calculates an average value of the absolute value of the integrated value at the time of voltage increase of the induced electromotive voltage e from time t1 to time t2 and the absolute value of the integrated value at the time of voltage decrease of the induced electromotive voltage e from time t3 to time t4. Is a magnetic flux Φ.

  FIG. 14 is a flowchart showing an example of a magnetic flux detection method. FIG. 15 is a time chart showing an example of a magnetic flux detection method. In step S80, the switch means 80 is turned off to stop energization of the electromagnetic solenoid 70. In step S82, the switch means 80 is turned on to apply a predetermined voltage, for example, the power supply voltage V, to the electromagnetic solenoid 70. For example, as shown in FIG. 15, it is assumed that the switch unit 80 is turned on at time t1. And after applying a predetermined voltage for a fixed time, the switch means 80 is turned off. For example, as shown in FIG. 15, it is assumed that energization of the electromagnetic solenoid 70 is stopped at time t3.

  In step S84, the product R × I of the current I and the resistance R detected by the actual current detecting means 122 is calculated as an actual voltage. In step S86, the induced electromotive voltage e is calculated from the difference between the actual voltage R × I and the applied voltage V according to the equation (8). In step S88, the induced electromotive force e is integrated from time t1 to time t2. For example, as shown in FIG. 15, when the induced electromotive voltage e is integrated from time t1 to time t2, the integrated value indicated by reference numeral S1 shown in FIG.

  In step S90, the induced electromotive voltage e is calculated from the difference between the actual voltage R × I and the applied voltage V ′ = 0 according to the equation (13). In step S92, the induced electromotive voltage e is integrated from time t3 to time t4. For example, as shown in FIG. 15, when the induced electromotive voltage e is integrated from time t3 to time t4, the integrated value indicated by reference numeral S2 shown in FIG. In step S94, the magnetic flux φ0 is calculated from the average value of the absolute value of the integrated value at the time of voltage increase and the absolute value of the integrated value at the time of voltage decrease.

  As described above, according to this embodiment, the same effects as those of the first and second embodiments can be obtained by combining the first and second embodiments.

Fourth Embodiment FIG. 16 is a functional block diagram of an electromagnetic actuator control means 400 according to a fourth embodiment of the present invention. Components substantially the same as those in FIG. 4 are given the same reference numerals. . The temperature detection unit 402 detects the temperature of the resistor R, for example, the temperature of the exciting coil 60. The temperature of the exciting coil 60 is determined by detecting the temperature of the lubricating oil of the electromagnetic actuator 56, for example.

  FIG. 17 is a block diagram of the magnetic flux detection means 404. Components that are substantially the same as those in FIG. 7 are denoted by the same reference numerals. The actual voltage temperature correction means 406 calculates the actual voltage R × I after correcting the temperature of the resistor R. For the temperature correction of the resistance R, for example, the resistance value R may be calculated according to the relational expression from the reference resistance value at a predetermined temperature from the temperature detected by the temperature detecting means 402, or the relationship between each temperature and the resistance value. May be stored in a table and a resistance value corresponding to the temperature may be searched for. When the resistance R includes a resistance other than the exciting coil 60, the temperature is also detected, the resistance value is corrected for temperature, and the resistance value corrected for each temperature is added.

  FIG. 18 is a flowchart showing an example of a magnetic flux detection method. In step S100, the switch means 80 is turned off to stop energization of the electromagnetic solenoid 70. In step S102, the switch means 80 is turned on to apply the voltage V to the electromagnetic solenoid 70. In step S104, the temperature of the electromagnetic solenoid 70 is measured. In step S106, the resistance value R is corrected according to the temperature of the electromagnetic solenoid 70, and the product R × I of the current I detected by the actual current detecting means 122 and the temperature-corrected resistance value R is calculated as an actual voltage. In step S108, the induced electromotive voltage e is calculated from the difference between the actual voltage R × I and the applied voltage V according to the equation (8). In step S110, the induced electromotive voltage e is integrated from time t1 to time t2. The magnetic flux φ0 is calculated from the integrated value at the time of voltage increase according to the equation (9).

  As described above, according to the present embodiment, the same effect as that of the first embodiment is obtained, and the resistance value is temperature-corrected. Therefore, the induced electromotive voltage e can be calculated more accurately, and the magnetic flux calculation can be performed. Accuracy can be improved.

Fifth Embodiment FIG. 19 is a block diagram of the magnetic flux detection means 450. Components that are substantially the same as those in FIG. 7 are given the same reference numerals. The magnetic flux detection means 450 calculates the actual voltage R × I described in the second embodiment after correcting the temperature of the resistor R. The temperature correction of the actual voltage is the same as in the fourth embodiment.

  FIG. 20 is a flowchart showing an example of a magnetic flux detection method. In step S150, the switch means 80 is turned off to stop energization of the electromagnetic solenoid 70. In step S152, the switch means 80 is turned on to apply the voltage V to the electromagnetic solenoid 70. In step S154, the switch means 80 is turned off to stop energization of the electromagnetic solenoid 70. In step S156, the temperature of the electromagnetic solenoid 70 is measured. In step S158, the resistance value R is corrected according to the temperature of the electromagnetic solenoid 70, and the product R × I of the current I detected by the actual current detecting means 122 and the temperature-corrected resistance value R is calculated as an actual voltage. In step S160, the induced electromotive voltage e is calculated from the difference between the actual voltage R × I and the applied voltage V ′ = 0 according to the equation (13). In step S162, the induced electromotive voltage e is integrated from time t3 to time t4. The magnetic flux φ0 is calculated from the integrated value at the time of voltage reduction according to the equation (14).

  As described above, according to the present embodiment, the same effect as that of the second embodiment is obtained, and the resistance value is temperature-corrected. Therefore, the induced electromotive voltage e can be calculated more accurately, and the magnetic flux calculation can be performed. Accuracy can be improved.

Sixth Embodiment FIG. 21 is a block diagram of the magnetic flux detection means 500, in which components that are substantially the same as those in FIG. 7 are given the same reference numerals. The magnetic flux detection means 500 calculates the actual voltage R × I described in the third embodiment after correcting the temperature of the resistor R. The temperature correction of the actual voltage is the same as in the fourth embodiment.

  FIG. 22 is a flowchart showing an example of a magnetic flux detection method. In step S200, the switch means 80 is turned off to stop energization of the electromagnetic solenoid 70. In step S202, the switch unit 80 is turned on to apply a predetermined voltage, for example, the power supply voltage V, to the electromagnetic solenoid 70. And after applying a predetermined voltage for a fixed time, the switch means 80 is turned off. In step S204, the temperature of the electromagnetic solenoid 70 is measured.

  In step S206, the resistance value R is temperature-corrected according to the temperature of the electromagnetic solenoid 70, and the product R × I of the current I detected by the actual current detecting means 122 and the temperature-corrected resistance value R is calculated as an actual voltage. In step S208, the induced electromotive voltage e is calculated from the difference between the actual voltage R × I and the applied voltage V according to the equation (8). In step S210, the induced electromotive force e is integrated from time t1 to time t2 to calculate an integrated value at the time of voltage increase.

  In step S212, the induced electromotive voltage e is calculated from the difference (R × I) between the temperature-corrected actual voltage R × I and the applied voltage V ′ = 0 according to the equation (13). In step S214, the induced electromotive force e is integrated from time t3 to time t4 to calculate an integrated value at the time of voltage decrease. In step S216, the magnetic flux φ0 is calculated from the absolute value of the integrated value at the time of voltage increase and the average value of the integrated value at the time of voltage decrease. The absolute value / 2 of (integral value at the time of voltage decrease−integral value at the time of voltage increase) is the same as the average value.

  By the way, when the excitation current I is zero, the applied voltage is unstable. For example, the induced electromotive voltage of the exciting coil 60 does not become zero, and an induced electromotive voltage (drift electromotive voltage) ed due to drift exists. Sometimes. This drift electromotive voltage ed can be regarded as substantially constant and is included in the induced electromotive voltage e, so that e = e0 + ed. e0 is a true induced electromotive force.

  For the induced electromotive voltage e, an integrated voltage increase value from time t1 to time t2 when the applied voltage is increased is S1. The integrated value (true voltage increase integrated value) of the true induced electromotive force e0 is S0 (<0). The integrated value (drift component) of the drift electromotive force ed is Sd ′ = ed × (t2−t1). Therefore, Expression (15) is established.

S1 = S0 + Sd ′ (15)
For example, as shown in FIG. 24, S1 = S2 + S3, Sd ′ = S4 + S3, and S0 = S2-S4. However, S2 is the integral value in the range of e <0 (<0), S3 is the integral value in the range of e ≧ 0 (> 0), and S4 is the decrease in the true integral value due to the drift electromotive force ed (> 0). (> 0).

  On the other hand, when the applied voltage V ′ is decreased, the voltage decrease integrated value from time t3 to t4 when the applied voltage is decreased is set to S11 for the induced electromotive voltage e. The integrated value (true voltage decrease integrated value) of the true induced electromotive force e0 is defined as S10. The integrated value (drift component) of the drift electromotive force ed is Sd ″ = ed × (t4−t3). Therefore, Expression (16) is established.

S11 = S10 + Sd ″ (16)
Here, if the integration time (t2-t1) at the time of voltage increase is equal to the integration time (t4-t3) at the time of voltage decrease, the drift component Sd ′ = Sd ″, and the equations (16) to (15) are obtained. When subtracted, Expression (17) is established.

S11−S1 = S10−S0 (17)
Since S10 and S1 have the same absolute value, the true integrated value from which the drift components Sd ′ and Sd ″ are removed is calculated by (integration value at the time of voltage decrease−integral value at the time of voltage increase) / 2. 22, the integration time (t2-t1) and (t4-t3) are made equal in steps S210 and S220 to calculate the magnetic flux φ based on the true induced electromotive voltage e0 from which the drift component has been removed. The true integrated value is also calculated by calculating the average value of the absolute value of the integrated value at the time of voltage increase and the absolute value of the integrated value at the time of voltage decrease.

  As described above, according to the present embodiment, the same effect as that of the third embodiment is obtained, and the resistance value is temperature-corrected. Therefore, the induced electromotive voltage e can be calculated more accurately, and the magnetic flux The calculation accuracy can be improved. Furthermore, it is possible to detect a magnetic flux with high accuracy based on the induced electromotive voltage from which the drift component has been removed.

  In the first to third embodiments, the resistance R is a fixed value. However, the resistance R is measured in consideration of the dependence of the resistance R on temperature, and the induced electromotive voltage is measured based on the measured resistance R. It is also possible to calculate e. When a predetermined voltage is applied to the exciting coil 60 for a predetermined time, for example, with the power supply voltage V as the applied voltage V ′, the exciting current I becomes a predetermined voltage / R, for example, V / R. Thereby, the resistance R becomes a predetermined voltage / I, for example, V / I. By substituting this resistance R into the equation (8) or the equation (13), the induced electromotive voltage e can be calculated.

  The resistor R applies a predetermined voltage to the exciting coil 60 for a predetermined time, for example, the power supply voltage V for a predetermined time before applying the voltage V ′ shown in FIG. 6 or the like to calculate the induced electromotive voltage e. Or the applied voltage V ′ for calculating the induced electromotive voltage e becomes a predetermined voltage, for example, the power supply voltage V, and is calculated from the current I when the voltage becomes constant. This resistance R is stored in a memory and used when calculating the induced electromotive voltage e. Since the power supply voltage V may fluctuate, the resistance R may be calculated after measuring the power supply voltage V or the like. In addition, when the applied voltage V ′ increases or decreases, the current I is measured, the applied voltage V ′ is measured, and the measured applied voltage V ′ and current I are substituted into the expression (3) to induce the induced voltage. e may be calculated, and the magnetic flux φ may be calculated based on Equation (4). At this time, the induced electromotive force e may be calculated by substituting the resistance R measured as described above into the equation (3).

  Moreover, although the magnetic flux detection apparatus used for an electromagnetic brake was demonstrated to the example in this embodiment, it is applicable if it is an electromagnetic clutch by which engagement of a clutch is controlled based on the magnetic flux by an exciting current.

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 principle of magnetic flux detection. It is a figure which shows the principle of magnetic flux detection. It is a functional block diagram of the magnetic flux detection means by 1st Embodiment of this invention. It is a flowchart which shows the magnetic flux detection method by 1st Embodiment of this invention. It is a time chart which shows the magnetic flux detection method by 1st Embodiment of this invention. It is a functional block diagram of the magnetic flux detection means by 2nd Embodiment of this invention. It is a flowchart which shows the magnetic flux detection method by 2nd Embodiment of this invention. It is a time chart which shows the magnetic flux detection method by 2nd Embodiment of this invention. It is a functional block diagram of the magnetic flux detection means by 3rd Embodiment of this invention. It is a flowchart which shows the magnetic flux detection method by 3rd Embodiment of this invention. It is a time chart which shows the magnetic flux detection method by 3rd Embodiment of this invention. It is a functional block diagram of an electromagnetic actuator control means. It is a functional block diagram of the magnetic flux detection means by 4th Embodiment of this invention. It is a flowchart which shows the magnetic flux detection method by 4th Embodiment of this invention. It is a functional block diagram of the magnetic flux detection means by 5th Embodiment of this invention. It is a flowchart which shows the magnetic flux detection method by 5th Embodiment of this invention. It is a functional block diagram of the magnetic flux detection means by 6th Embodiment of this invention. It is a flowchart which shows the magnetic flux detection method by 6th Embodiment of this invention. It is a time chart which shows a drift induced electromotive voltage.

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 Multi-plate brake 56 Electromagnetic actuator 58 Core (yoke)
60 Excitation coil 62 Armature 70 Electromagnetic solenoid 80 Switch means 100, 400 Electromagnetic actuator control means 110, 300, 404, 450, 500 Magnetic flux detection means 114 Target control current value calculation means 116 PID calculation means 122 Current detection means 150 Current supply means 152 Actual Voltage calculation means 154, 302, 352 Induction voltage calculation means 156, 354 Magnetic flux calculation means 402 Temperature detection means 406 Actual voltage temperature correction means

Claims (2)

A core and an armature facing each other through an air gap, an excitation coil for generating a magnetic flux in the core, the armature and the air gap, a voltage applying means for applying a voltage to the excitation coil, and a magnetic flux generated in the air gap A magnetic flux detection device for an electromagnetic clutch having a multi-plate clutch fastened based on
Electromagnetic clutch non-engagement detecting means for detecting whether or not the electromagnetic clutch is in a non-engaged state;
First energization control means for controlling the voltage application means to increase the applied voltage of the excitation coil when the electromagnetic clutch non-engagement detection means detects the non-engagement state of the electromagnetic clutch;
Current detecting means for detecting a current value of a current flowing through the exciting coil;
Based on the applied voltage, a resistance value related to a path through which the current flows, and the current value when the applied voltage is increased detected by the current detection unit, an induced electromotive voltage when the applied voltage is generated in the exciting coil is increased. First induced electromotive force calculation means for calculating
Second energization control means for controlling the voltage application means to reduce the applied voltage of the exciting coil;
Based on the applied voltage, a resistance value associated with a path through which the current flows, and the current value when the applied voltage is decreased detected by the current detection unit, an induced electromotive voltage when the applied voltage is reduced in the exciting coil. Second induced electromotive force calculation means for calculating
The induced electromotive voltage when the applied voltage is increased and when the applied voltage is decreased is time-integrated, and the magnetic flux of the exciting coil is calculated based on the difference value between the integrated values when the applied voltage is increased and when the applied voltage is decreased. Magnetic flux calculating means for
A magnetic flux detection device comprising:   The temperature detecting means for detecting the temperature of the exciting coil, and the temperature correcting means for correcting the resistance value based on the temperature of the exciting coil detected by the temperature detecting means, the induced electromotive voltage calculating means, 2. The magnetic flux detecting device according to claim 1, wherein the induced electromotive voltage is calculated based on the resistance value corrected by the temperature correcting means.

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