JP2005086872A - Power window clipping prevention device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an improved power window clipping prevention device capable of limiting a motor current by quickly detecting an abnormal current of a motor with no erroneous recognition due to the pinching of a foreign substance. <P>SOLUTION: The power window clipping prevention device uses a constant current circuit for operation with a stabilized voltage Vcc. While no clipping is detected, a part of current component of a reference current Iref is shunted from the connection part between resistors R24 and R27 of a follow-up current limit circuit for less amount of current, and when clipping is detected, operation of the constant current circuit is stopped to increase the amount of current of the current component Iref-f of the reference current Iref, thus performing current control without affected by fluctuation of a power supply voltage. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a power window pinching prevention device that prevents a foreign object (for example, a human finger, a neck, etc.) from being pinched by a power window of a vehicle.

  A device for automatically opening and closing a window glass of a vehicle is generally called a power window, and opens and closes the window glass by a motor. In order to prevent jamming protection (that is, jamming protection) as a measure to prevent foreign objects from being caught by the wind glass, a power window pinching prevention device is adopted in the power window, but in a general power window pinching prevention device, When a foreign object is caught while the window glass is rising, the load applied to the caught foreign substance increases remarkably due to an increase in motor current, so the motor current is limited to suppress this increase in motor current. There was a need to do.

In view of the above circumstances, an improved power window pinching prevention device has been proposed (see, for example, Patent Document 1).
JP 2002-295129 A

  The power window pinching prevention device proposed in Patent Document 1 will be described in detail with reference to the accompanying drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

(Outline of power window pinching prevention device)
FIG. 3 is a block diagram of an example of a power window pinching prevention device proposed in Patent Document 1. In FIG. This power window pinching prevention device has an abnormal current detection circuit 2 due to pinching or the like, a power window motor 5 provided with a forward / reverse circuit, a pinching determination circuit 6, and a motor current limiting circuit 7. Yes. The power window motor 5 provided with the forward / reverse circuit may be considered as the forward / reverse circuit 5 including the power window motor. The three circuits of the current detection circuit 2, the normal rotation / inversion circuit 5, and the current limiting circuit 7 are connected in series to the electric wire 1 through which the motor current ID flows and are connected to the power supply device VB.

(Outline of abnormal current detection circuit 2 due to pinching, etc.)
The current detection circuit 2 detects an abnormal current due to the motor current ID being sandwiched or the like, and outputs an abnormal current detection signal to the current limiting circuit 7 via the signal line 9. The current detection circuit 2 includes a multi-source field effect transistor (FET) or a multi-resistance, a current tracking circuit 3, and a start circuit 4.

  The multi-source FET is composed of a main FET and a reference FET. The multi-resistor includes a shunt resistor and a reference resistor. The current sensing ratio (n: Current Sensing Ratio) of the multi-source FET or multi-resistor, that is, the ratio of the resistance component of the reference resistor to the main resistor, for example, is set to more than 1 and preferably 100 or more. The motor current ID is passed through the main FET or shunt resistor. Then, the reference current Iref is controlled so that the reference current Iref that satisfies the condition of ID = n * Iref flows through the reference FET or the reference resistor.

  When the main FET or shunt resistor is on the high side of the motor (High side: power supply side with respect to the motor), the source potential of the main FET or the motor side potential VSA of the shunt resistor and the source potential or reference resistance of the reference FET The ground side potential VSB needs to satisfy the condition of VSA = VSB in order to satisfy the condition of ID = n * Iref. When the motor is rotating normally, if the motor current ID changes due to fluctuations in the driving force of the window glass, the source potential such as the source potential of the main FET also changes, but the reference current Iref is controlled to maintain the condition of VSA = VSB. .

  Next, a method for detecting an abnormal current generated due to jamming or the like will be described.

  The reference current Iref is divided into two current components having different following speeds. The reference current Iref flows by being divided into a current component Iref-s having a slow following speed and a component Iref-f having a fast following speed. The slow current component Iref-s follows the change in the motor current ID when the motor is rotating normally, but cannot follow the sudden change in the motor current ID when pinching occurs. Set as follows. On the other hand, the current component Iref-f having a fast follow-up speed is set so that it can follow not only the current change when pinching occurs but also the pulsation component included in the motor current ID. The better the followability of the current component Iref-f with the fast following speed, the more stable the current component Iref-s with the slow following speed need not be changed. In order to satisfy such conditions, the following speed of the current component Iref-f having a fast following speed is set to a speed 800 to 1000 times that of the current component Iref-s having a slow following speed.

  With this setting, the current component Iref-f having a fast follow-up speed accurately reflects the change in the motor current ID except when the semiconductor switching element is turned on / off. A change in the motor current ID is converted into a voltage by flowing a current component Iref-f having a fast following speed through a resistor having a resistance value larger than that of the reference resistor. By this voltage conversion, it is possible to detect a change obtained by amplifying a minute change obtained by converting a change in the motor current ID into a voltage by the shunt resistor or the on-resistance of the main FET.

  When pinching occurs, the current component Iref-f having a fast following speed increases following the motor current ID, but the current component Iref-s having a slow following speed hardly changes. Therefore, there is a difference between the average value of the current component Iref-f having a fast following speed and the current component Iref-s having a slow following speed, resulting in a magnitude relationship of (average value of Iref-f)> (Iref-s). . If this difference exceeds a preset value, an abnormal current detection signal is generated and a multi-source FET on the high side of the motor or a current limiting circuit on the low side of the motor (low side: ground side) 7 semiconductor switching element (FET or bipolar transistor) is turned off.

  Thereafter, while the pinching occurs, the multi-source FET or the semiconductor switching element on the low side of the motor performs the operation of repeating the On / Off operation and the continuous On operation. As will be described below, the increase in the motor current ID can be limited by the operation of repeating the On / Off operation and the continuous On operation.

(Outline of current limiting circuit 7)
The current limiting circuit 7 receives the abnormal current detection signal and limits the motor current ID so as not to increase. This restriction is performed by the semiconductor switching element on the low side of the multi-source FET or the motor that alternately repeats the On / Off operation and the continuous On operation, and the signal of the operation that repeats the On / Off operation and the continuous On operation is a signal. It is output to the pinching determination circuit 6 via the line 10. The current limiting circuit 7 includes a semiconductor switching element such as an FET that can turn on / off the motor current ID, and a reference voltage circuit 8 that generates an On reference voltage and an Off reference voltage of the semiconductor switching element. Have.

  When the motor current ID enters an operation in which On / Off operation and continuous On are repeated, the motor current ID is current-limited, and its average value is sandwiched and maintained at a slightly larger value than immediately before the occurrence. Since the motor torque is proportional to the motor current, this keeps the motor torque slightly larger than the torque required to drive the window glass. By securing such a necessary minimum torque, it is possible to realize the minimum pinched load under the condition that even if there is an instantaneous fluctuation of the glass driving force due to a bad road or the like, it does not reverse in error. Become.

(Outline of the pinch detection circuit 6)
The pinch determination circuit 6 determines whether or not the pinch is pinched based on the input operation signal that repeats the On / Off operation and the continuous On operation. If it is determined that the pinch has occurred, a window down signal for opening the window glass is output to the normal rotation / inversion circuit 5 via the signal line 11.

  The determination of pinching utilizes the fact that the on / off operation period of the semiconductor switching element becomes longer and the continuous on operation period of the semiconductor switching element becomes shorter as the motor rotation speed decreases due to pinching. For example, when the period of the On / Off operation reaches a certain length, it is determined that the jamming has occurred. If it is determined that the pinch has occurred, the multi-source FET or the semiconductor switching element is cut off, the motor is stopped, and the motor 5 is driven in reverse after a predetermined time has elapsed. As a result, the window glass is opened, and the trapped foreign matter can be prevented from being caught.

(Outline of power window motor 5 with forward / reverse circuit)
The forward rotation / inversion circuit 5 rotates the motor in the direction to close the window glass by inputting the window up signal, and rotates the motor in the direction to open the window glass by inputting the window down signal. Further, when a window down signal is input via the signal line 11, the rotation of the motor is reversed from the direction of closing the window glass to the direction of opening. The normal rotation / inversion circuit 5 has an H bridge circuit or a relay circuit. When the H bridge circuit is used, four FETs constituting or connecting the H bridge circuit are used. Of the four FETs, the high-side transistor may be used to form the current detection circuit 2 and the current limiting circuit 7, or the high-side transistor may be used to form the current detection circuit 2 and the low-side transistor may be used. The current limiting circuit 7 may be configured.

  FIG. 4A to FIG. 4C show a modification of the block diagram of the power window pinching prevention device. In other words, the current detection circuit 2 is connected to a ground equivalent to the plus terminal or the minus terminal of the power supply device VB, and the order in which the motor current ID flows in the normal rotation / inversion circuit 5 and the current limiting circuit 7 may be arbitrary. Specifically, as shown in FIG. 4 (a), the current detection circuit 2 → the current limiting circuit 7 → the normal rotation / inversion circuit 6 and the current detection circuit 2 as shown in FIG. 4 (b). → forward / invert circuit 5 → order of current limiting circuit 7 (that is, the same order as shown in FIG. 1), forward / invert circuit 5 → current limiting circuit as shown in FIG. 4 (c) The order of 7 → current detection circuit 2 may be used, and it may be considered that the difference in the order and the like does not cause a great difference in the operation and effect of the power window pinching prevention device.

FIG. 5 shows an example of a circuit diagram of the power window pinching prevention device. The circuit configuration and circuit operation of the current detection circuit 2, the current limiting circuit 7, and the pinch determination circuit 5 in the power window pinch prevention device will be described in detail here.
1. Description of current detection circuit 2 1-1. Circuit Configuration of Current Detection Circuit 2 A circuit that detects an abnormal current by using a shunt resistor and a reference resistor and dividing the reference current Iref into two current components Iref-s and Iref-f having different following speeds will be described.

  The current detection circuit 2 of FIG. 5 includes a shunt resistor R1 and a reference resistor R20 connected to the plus terminal of the power supply device VB, a current tracking circuit 3 connected to the resistors R1 and R20, and a plus input terminal to the current tracking circuit 3. A comparator CMP2 connected to the negative input terminal and connected to the current limiting circuit 7 at the output terminal, and a resistor R25 connected between the 5V power source and the output terminal of CMP2.

  The current tracking circuit 3 has a positive input terminal connected to the reference resistor R20, a negative input terminal connected to the shunt resistor R1, a comparator CMP1 connected to the output terminal of CMP1, and a resistor C21 connected to the ground in series with the capacitor C1. The first charging / discharging circuit configured as described above, the second charging / discharging circuit configured by connecting the resistor R22 and the grounded capacitor C2 connected in series to the output terminal of CMP1, and between the capacitors C1 and C2 Connected to the resistor R28 to be connected, the nMOSFET (T21) whose drain terminal is connected to the positive input terminal of CMP1 and the gate terminal is connected to the capacitor C1, the source terminal of the FET (T21) and the positive input terminal of CMP2 A first source follower circuit composed of a resistor R23 whose other end is grounded, and a drain terminal of CMP1. The nMOSFET (T22) connected to the laser input terminal and the gate terminal connected to the capacitor C2, the diode D21 connected to the source terminal of the FET (T22), the anode, the cathode of the diode D21, and the negative input terminal of CMP2 A second source follower circuit including a resistor R24 connected and grounded at the other end.

Note that 910K added to the resistor R21 and the like in FIG. 5 indicates that the resistance value of the resistor R21 is 910 KΩ. Similarly, 0.1 uf attached to the capacitor C2 and the like indicates that the capacitance of the capacitor C2 is 0.1 μF.
1-2. Description of Operation of Current Detection Circuit 2 In FIG. 5, the shunt resistor R1, the forward / reverse relay circuit 5, and the semiconductor switching element (FET) T1 that performs the on / off operation are connected to the electric wire 1 through which the motor current ID flows. Are connected in series, and are connected to a positive terminal and a negative terminal of a power supply device (for example, battery) VB. The forward / reverse relay of the forward / reverse relay circuit 5 is driven by the transistors T2 and T3, and T2 is turned on for forward rotation (up operation) and T3 is turned on for inversion (down operation). . The multi resistor is composed of a shunt resistor R1 and a reference resistor R20. In the circuit example of FIG. 5, the resistance value of R1 is set to 34 mΩ, and the resistance value of R20 is set to 55Ω. The motor current ID flows through the shunt resistor Rl, and the reference current Iref flows through the reference resistor R20. For the sake of convenience, the resistance values and the capacitances of the resistor R1 and the capacitor C2 are denoted by the same R1 as the symbol R1 of the resistor R1. Therefore, the current ratio n when the condition of R1 * ID = R20 * Iref is satisfied is as shown in Equation 1.

n = m / Iref = R20 / R1 = 55 / 0.034 = 1618 ... Formula 1
The comparator CMP1 is composed of an operational amplifier. The motor side potential of the shunt resistor R1 is input to the minus input terminal of the CMP1, and the ground side potential of the reference resistor R20 is input to the plus input terminal of the CMP1. A first charge / discharge circuit in which a resistor R21 and a capacitor C1 are connected in series is connected between the output of CMP1 and the ground potential level (GND), and the capacitor C1 is charged / discharged through the resistor R21 by the output of CMP1. The non-grounded side of the capacitor C1 is connected to the gate terminal of the FET 21, the drain terminal of the FET T21 is connected to the reference resistor R20, and the source terminal of T21 is grounded through the resistor R23. Since the FET T21 and the resistor R23 constitute a first source follower circuit, a current proportional to the potential of the capacitor C1 flows through the FET T21 and the resistor R23. This current becomes a current component Iref-s having a slow following speed of the reference current Iref. On the other hand, a second charge / discharge circuit in which a resistor R22 and a capacitor C2 are connected in series is connected between the output of the comparator CMP1 and the ground potential level (GND). The capacitor C2 is charged / discharged via the resistor R22 by the output of CMP1. Is done. The non-ground side of the capacitor C2 is connected to the gate terminal of the FET T22 via the resistor R28, the drain terminal of the FET T22 is connected to the reference resistor R20, and the source terminal of the FET T22 is grounded through the diode D21 and the resistor R24. . Since the FET T22, the diode D21, and the resistor R24 form a second source follower circuit, a current proportional to the potential of the capacitor C2 flows through the FET T22, the diode D21, and the resistor R24. This becomes a current component Iref-f having a fast following speed in the reference current Iref. The non-grounded sides of the capacitors C1 and C2 are connected by a resistor R28, and the potentials of C1 and C2 are equal when the motor current ID does not change. That is, the output of the comparator CMP1 is connected in parallel with two charge / discharge circuits composed of capacitors C1 and C2 and resistors R21 and R22, and two source follower circuits for supplying a current proportional to the potentials of the capacitors C1 and C2 are provided. The reference resistor R20 and the ground are connected in parallel. The time constant of the first charge / discharge circuit is set larger than the time constant of the second charge / discharge circuit. In this circuit example, the time constant of the first charging / discharging circuit is expressed by Equation 2, the time constant of the second charging / discharging circuit is expressed by Equation 3, and the ratio is 1: 894.

(Time constant of the first charge / discharge circuit) = R21 * (R22 + R28) / (R21 + R22 + R28) * C1
= 910K * (5.1K + 910K) / (910K + 5.1K + 910K) * μf = 456 ms (2)
(Time constant of the second charge / discharge circuit) = R22 * C2 = 5.1K * 0.1 μf = 0.51 ms Equation 3
The sandwiching is detected by the comparator CMP2. The source potential of T21 is input to the plus input terminal of CMP2, and the potential that is lower than the source potential of the FET T22 by about 0.7V in the forward voltage drop of the diode D21 is input to the minus input terminal. Since the gate-source potentials of T21 and T22 are substantially equal, the detected value of the abnormal current that increases due to the voltage drop of D21 is sandwiched. When pinching occurs and Iref-f increases, the output of CMP2 (current limiting control signal CPOUT_B) changes from H level to L level. Then, the output of NOR1 of the current limiting circuit 7 becomes H level, the transistor T31 is turned on, and the transistor T1 that is a semiconductor switching element is turned off. Detection of abnormal current due to pinching at this time is performed as follows.

  (A) First, the reference current Iref is divided into a component Iref-s having a low following speed and a component Iref-f having a fast following speed as shown in FIG. The change in the motor current ID appears in Iref-f including the pulsating component and is accurately reflected in the source potential of the FET T22, that is, the minus input terminal voltage (Vins) of the CMP2. As a result, the source potential of T21 on the Iref-s side, that is, the positive input terminal voltage (Vc) of CMP2 is not affected by the fast fluctuation of the motor current ID, and only the long-term average value is reflected. For this reason, an ideal reference voltage can be realized by maintaining a substantially constant potential while the current is limited due to the pinching.

  (B) The component Iref-f having a fast following speed includes a fluctuation due to the pulsating component of the motor current. When the amplitude of the pulsating current is ΔID-rip and the pulsating component of Iref-f is ΔIref-f-rip, ΔIref-f-rip = ΔID-rip / n. The voltage fluctuation ΔVrip generated in the resistor R24 due to ΔIref-f-rip is 0.46 V when R24 = 1.5 kΩ and ΔID-rip = 0.5 A as shown in Equation 4.

△ Vrip = △ Iref-f-rip * R24
= △ ID-rip / n * R24 = 0.5A / 1618 * 1.5K = 0.46V Equation 4
That is, the negative input terminal voltage of CMP2 is oscillated with an amplitude of ± 0.23 V (± ΔVrip / 2) due to a pulsating component. Accordingly, when the average value of Iref-f increases by 0.47V (= 0.7V−0.23V), the output of CMP2 is inverted from the H level to the L level.

When this 0.47V is converted into motor current ID, 0.51A (= 0.47V / R24 * n =
0.47V / 1.5K * 1618). That is, in the circuit example of FIG. 5, when the average value of the motor current ID increases by 0.51 A due to the pinching, the output of CMP2 becomes L level, T31 is turned on, and T1 is turned off.

  (C) As shown in FIG. 6, before the output of CMP2 is inverted to the L level (before time t1), the motor current ID increases, so the output of CMP1 is at the H level. When T31 is turned on, the motor current ID begins to decrease with a delay by the time over which the overcharged charge on the gate of T1 is discharged. At this time, the output of CMP1 starts to transition from the H level to the L level, but because CMP1 is composed of an operational amplifier, a delay time occurs until the output changes from H to L due to the response delay of the operational amplifier. To do.

  Since C2 is charged during the time t1 from when the output of CMP2 is inverted to the L level until the CMPl output decreases from the H level and becomes equal to the potential of the capacitor C2, Iref-f increases, and CMP2 Negative input terminal voltage increases. Thereafter, when the output of CMP1 becomes lower than the C2 potential, C2 starts to be discharged, and after time t2 until the amount of charge charged during time t1 is completely discharged, the negative input terminal voltage of CMP2 is the original voltage, that is, CMP2 The voltage returns to the voltage when the output starts to transition from H to L. During this time, the positive input terminal voltage does not change.

  After the time t2, the CMP2 output is inverted to H level, and the FET T1 is turned on. That is, after the motor current ID increases and the output of CMP2 is inverted to the L level, the CMP2 output maintains the L level at the time t1 + t2. When the potential of C2 is between the H level and L level of the output of CMP1, the relationship of t1≈t2 is established. The time t1 + t2 is determined by the turn-off delay time of T1, the response speed of the operational amplifier, and the reduction speed of the motor current ID. However, since the turn-off delay time of T1 and the response speed of the operational amplifier are constant, the time t1 + t2 is a reduction of the motor current ID. Depending on the speed, it decreases as the rate of decrease decreases.

  When the CMP2 output changes from L to H again and T1 is turned on, the motor current ID starts to increase. Therefore, the output of CMP1 goes from L to H, but C2 continues to be discharged while the output of CMP1 is lower than the potential of C2. A time from when the output of CMP2 is inverted to H level until the output of CMP1 becomes equal to the potential of the capacitor C2 is defined as time t3. When the output of CMP1 exceeds the C2 potential, C2 begins to be charged. When a time t4 until the same amount of charge as that discharged at time t3 is charged, the output of CMP2 is inverted to L and T1 is turned off. That is, the output of CMP2 is maintained at the H level during the time t3 + t4. The time t3 + t4 is determined by the response speed of the operational amplifier and the increase speed of the motor current ID. However, since the response speed of the operational amplifier is constant, the time t1 + t2 depends on the increase speed of the motor current ID. Shorter.

  (D) The reason why the forward voltage drop of the diode D21 is used for setting the pinching detection value is to make the pinching detection value constant even when the motor current ID changes and the average value of Iref-f changes. . However, in this method, when it is necessary to change the pinching detection value, the forward voltage drop of the diode D21 cannot be changed. Therefore, the value of the resistor R24 is adjusted. As can be seen from the description of the above item (b), when the value of R24 is increased, the pinching detection value is decreased, and conversely, when the value of R24 is decreased, the pinching detection value is increased.

  (E) A child can be set by using a resistor instead of the die auto D21 for setting the pinching detection value. In this case, when the motor current ID increases, the pinching detection value increases in proportion to it.

2. 2. Description of current limiting circuit 7-1. Circuit Configuration of Current Limiting Circuit 7 The current limiting circuit 7 of FIG. 5 includes a NOR gate NOR1 whose input terminal is connected to the output terminal of CMP2, a comparator CMP3 whose output terminal is connected to the input terminal of NOR1, and a negative input terminal of CMP3. A reference voltage circuit 8 connected to the semiconductor switching element T1, a drain terminal connected to the positive input terminal of CMP3, a source terminal grounded, a variable resistor R32 connected to the gate terminal of the switching element T1, and a gate terminal Is connected to the output terminal of NOR1, the drain terminal is connected to the resistor R32, the source is grounded FET (T31), the resistor R31 connected between the plus terminal of the power supply device VB and the drain terminal of T31, A resistor R33 connected between the positive input terminal of CMP3 and the ground, and between the output terminal of CMP3 and the 5V power supply And a resistor R37 connected to the.

  The reference voltage circuit 8 is connected to a resistor R35 connected between the minus input terminal of CMP3 and the power supply device VB, a resistor R36 connected between the minus input terminal of CMP3 and the ground, and a minus input terminal of CMP3. A resistor R34, a diode D31 having an anode connected to the resistor R34, a drain terminal connected to the cathode of the diode D31, a source terminal grounded, and a gate terminal connected to the output terminal of CMP3 (T32); have.

2-2. Explanation of Operation of Current Limiting Circuit 7 The motor current ID is limited by combining the current detection circuit 2 and the current limiting circuit 7 of FIG.

First, the operation of the current limiting circuit 7 will be described. When the output of the comparator CMP2 of the current detection circuit 2 is H level, the output of the NOR gate NOR1 becomes L level, the transistor T31 is turned off, and the switching element (transistor) T1 is turned on. Next, the case where T1 is an FET will be described. At this time, the positive input terminal voltage of the comparator CMP3 is connected to the drain terminal of T1, and therefore the ground potential level is almost inputted. On the other hand, the negative input terminal voltage of CMP3 is determined by the reference voltage circuit 8 composed of R34, R35, R36, a diode D31 and a transistor T32. When R34 = 3.3KΩ, R35 = 10KΩ, and R36 = 24KΩ, the power supply voltage is set. When VB is 12.5V, it is 8.82V if T32 is off, and 3.03V if T32 is on. In any case, since it does not drop below 3.03 V, the CMP3 output becomes L level. Therefore, T32 is off. When pinching occurs and the output of the comparator CMP2 becomes L level, the output of NOR1 becomes H level, T31 is turned on, and T1 is turned off. The drain voltage VDS of T1 starts to rise from the ground potential level. Since T32 is off, the negative input terminal voltage of CMP3 is 8.82V. When the drain voltage VDS of T1 becomes 8.82V or more, the output of CMP3 is inverted to H level and the output of NOR1 is L level. , T31 is turned off and T1 is turned on. At this time, T32 is also turned on at the same time, so the negative input voltage of CMP3 drops to 3.03V. Accordingly, once T1 is turned on, the on state is maintained until the drain voltage VDS is lowered to 3.03 V or less. When the drain voltage VDS of T1 becomes 3.03V or less, the output of CMP3 becomes L level again, T1 turns off, T32 turns off at the same time, and the negative terminal input of CMP3 rises to 8.82V. T1 continues to turn off until the drain voltage VDS of T1 exceeds 8.82V. This is one cycle of the On / Off operation, and this state continues as long as the output of CMP2 is at L level.
● Invariance of motor current ID in On / Off operation Next, it will be described that when the On / Off operation is performed, the motor current ID hardly changes in one cycle of the On / Off operation. FIG. 7 shows a static characteristic curve to which a load line of the FET T1 is added. When the motor before the occurrence of pinching is rotating normally, T1 is operating at point A. When the motor load current ID changes, the operating point moves up and down between, for example, points A and B in the ohmic region. When pinching occurs, the motor load current ID increases, the operating point of T1 moves upward, and when B is reached, Tl is turned off. The current difference between point B and point A is the sandwiching detection value. When T1 is turned off, the drain-source voltage VDS increases, but the operating point of T1 at that time moves to the right on the horizontal line passing through the B point. In other words, the drain-source voltage VDS of T1 increases while the drain current ID (= motor load current) maintains the value when T1 is turned off. This is because when the drain-source voltage VDS of T1 is moving between the ground potential level and the power supply voltage, the gate-drain capacitance of Tl is apparently increased due to the Miller effect, and the gate-source voltage is increased. This is because the voltage VGS hardly changes.
FIG. 8 is an equivalent circuit diagram of the switching element T1. It is assumed that the gate-source voltage VGS has increased by a minute voltage ΔVGS due to charging by the gate driver. As a result, the motor current ID increases by ΔID, and the back electromotive force Ec (= L * dID / dt) is generated by the inductance L of the motor. The charge ΔQ charged in the gate-drain capacitance CGD is expressed by Equation 5.

ΔQ = CGD * (ΔVGS + ΔID * Ra + Ec) Equation 5
Here, Ra is an armature resistance. Further, the capacitance Cm of the CGD viewed from the gate terminal is expressed by Expression 6.

Cm = ΔQ / ΔVGS = CGD * (1 + ΔID * Ra / ΔVGS + Ec / ΔVGS) (Formula 6)
This is an apparent capacitance that occurs because the capacitance Cm is “Miller capacitance” and the voltage change across the capacitance CGD is much larger than ΔVGS. When the gate driver charges and discharges the gate charge of the FET through the gate resistor RG, the capacitance seen from the driver side is Cm instead of CGD. When the inductance L of the motor is large, the capacitance Cm becomes larger than CGD, and the gate-source voltage VGS hardly changes even when the gate driver charges and discharges the gate of T1 during the On / Off operation. However, the Miller effect is effective only when the drain potential VDS of the main FET (T1) is between the ground lightning level (GND) and the power supply voltage (VB) and can be freely changed. At this time, since T1 is in the pinch-off region, ID = Gm * VGS is established when the transfer conductance of T1 is Gm. From this equation, it can be seen that if VGS is substantially constant, the ID does not change and is substantially constant.

In FIG. 5, the negative input terminal voltages of the comparator CMP3 when the transistor T32 is on and off are VL and VH, respectively, in FIG. In this circuit example, VL = 3.03V and VH = 8.82V. When the operating point of T1 moves to the right on the horizontal line passing through point B in FIG. 7 and the drain voltage VDS becomes higher than the voltage VH, the output of CMP3 becomes H level and T1 is turned on. In an actual circuit, it is turned on after VH has been exceeded due to the delay of the circuit. In FIG. 7, the VDS is turned on at the point C where the voltage exceeds 10 V, and the VDS decreases toward the ground potential level. When VDS becomes lower than the voltage VL, the output of CMP3 becomes L level and T1 is turned off again. In this way, T1 continues the On / Off operation as long as the output of CMP2 is at the L level.
● Reduction of ID by On / Of Operation Next, it will be described that the drain current ID gradually decreases while the On / Of operation is continued. Since the drain voltage VDS of T1 is regulated by the reference voltages VL and VH when the On / Off operation is started, the operating point of T1 oscillates between the points C and D in FIG. At this time, the average value of VDS is G point, which is approximately the center between C point and D point. Point G is the DC operating point of T1. On the other hand, the line segment CD is an AC operating curve. In FIG. 7, a straight line a is a load straight line of T1 when the motor is stopped when the power supply device VB is 12.5V, and the gradient is determined by the armature resistance Ra. The straight lines b to g are parallel to the straight line a, and their projections on the horizontal axis can represent the amount of voltage drop when the drain current ID (= motor current) flows to the motor.

  First, let us consider the situation immediately before pinching occurs. The operating point of T1 at this time is point A. When the motor back electromotive force is Emotor-A and the drain-source voltage is VDSon, Equation 7 is established.

VB = VDSon + Ra * ID + Emotor-A (Formula 7)
Next, consider immediately after the occurrence of pinching and the start of the On / Off operation. The ID is composed of an AC component IDA that varies in synchronization with the On / Off operation and other DC component IDD. That is, ID has a relationship of ID = IDA + IDD. When IDD changes, back electromotive force Eonoff is generated by motor inductance L. Its size is obtained from Equation 8.

VB = VDScnoff + Ra * ID + Emotor-A + Eonoff (Formula 9)
By subtracting both sides of Equation 9 from both sides of Equation 7, Equation 10 can be obtained.

0 = VDSon-VDSonoff-Eonoff
Eonoff = VDSon−VDSonoff (Formula 10)
Here, VDSon is a drain-source voltage at the time of continuous on, and is about 0.3V. VDSonoff is a voltage at the point G and is approximately 6.5V. As a result, Eonoff becomes a negative value of −6.2 V from Equation 10. Since Eonoff becomes a negative value, it can be seen from Equation 8 that IDD decreases.
● Realization of minimum reversal load (preventing malfunction due to bad roads etc.) When DC component IDD of ID decreases from operating point G to operating point H while performing On / Off operation, Iref-f becomes IDD When the IDD reaches the H point in FIG. 7, the CMP2 is inverted from the L level to the H level, the operating point of the FET T1 moves from the H point to the F point, and T1 is in a continuous On state. become. In the continuous on state, ID increases, reaches point B via point A, and T1 enters the On / Off operation again. During this time, since Iref-s does not change, the positive input terminal voltage of CMP2 does not change, so point A is fixed and points B to F do not change accordingly. Therefore, the current value of the current ID is limited to a certain range while the on / off operation and the continuous on state are repeated.

  The average value of the current ID limited to the certain range is maintained at a value slightly larger than the current value of the ID immediately before entering the current limiting operation. This has two important implications.

  First, since the motor torque is proportional to the current, the motor torque can be limited to a certain range. Thereby, the pinching load can be limited.

Secondly, it is possible to prevent a malfunction that the vehicle reverses in spite of the occurrence of pinching by running on a rough road or the like. When operating the power window while driving on rough roads, the driving force of the wind glass changes due to the vertical movement of the vehicle body, the driving force increases instantaneously, and the motor rotation speed decreases accordingly, There is a possibility that ID increases, T1 is turned off, and the current limiting mode is entered. However, since the glass driving force immediately before the current limit mode is maintained, when the load increase due to the vertical movement is eliminated, the motor rotation speed can be recovered based on it to avoid erroneous reversal. However, it is assumed that the glass driving force does not change during this period. And this premise holds in most cases. With the above features, the minimum reversal load can be realized under the condition that no erroneous reversal occurs when the instantaneous driving force increases due to a rough road or the like.
● Changes in On / Off operation period and continuous On period due to decrease in motor rotation speed Next, let us consider the case where equations 7 and 9 are generalized. After a while, the motor speed decreases. Since the motor back electromotive force is proportional to the motor speed, assuming that the motor back electromotive force at that time is Emotor-B shown in FIG. 9, the relationship of Emotor-B <Emotor-A is established. With this reduced rotational speed, that is, the back electromotive force of the magnitude of Emotor-B, when T1 is in a continuous On state, the speed of increase in ID becomes faster than before, and the back electromotive force Eon is generated by the inductance L of the motor. To do. Eon = L * dID / dt. Eon has nothing in Eq. 7, and rewriting Eq. 7 using this formula gives Eq.

VB = VDSon + Ra * ID + Emotor-B + Eonoff (Formula 11)
The expression of On / Off operation corresponding to Expression 11 is expressed by Expression 12 by replacing Emotor-A of Expression 9 with Emotor-B, assuming that the motor speed does not change between continuous On and On / Off operations.

VB = VDSonoff + Ra * ID + Emotor-B + Eonoff (Formula 12)
Equation 13 is obtained from Equation 11 and Equation 12.

Eon-Eonoff = VSDonoff-VDSon = 6.5V-0.3V = 6.2V Equation 13
Since the sign of Eon is plus and the sign of Eonoff is minus, the meaning of Equation 13 is that the back electromotive force Eon at the time of continuous on and the back electromotive force Eonoff at the on / off operation have opposite signs and their absolute values. The sum is constant and is equal to the difference VDSonoff−VSDon of each VDS. The difference in VDS is constant regardless of the motor speed. As Emotor-B decreases as the motor speed decreases, the absolute value of Eonoff decreases and the absolute value of Eon increases. That is, it can be seen that when the motor rotation speed decreases, the ID decrease rate during On / Off operation decreases, and the ID increase rate during continuous On decreases.

Further, as can be seen from FIG. 7, Eonoff (point H) of Eonoff (point H) when exiting On / Off action (Eonoff-D in FIG. 7) immediately after entering On / Off action (point G). Eonoff-C) is smaller. This represents that the current decrease rate is gradually reduced during the On / Off operation period. In FIG. 7, the fact that Eon-E is smaller than Eon-F indicates that the rate of increase in current is gradually reduced during the continuous On period.
On / Off Operation Period When T31 is turned on, the gate charge of T1 is discharged through R32, and the gate-source voltage VGS of T1 starts to decrease. Since ID = Gm * VGS, the ID starts to decrease. Due to the decrease in ID, a counter electromotive force Ec is generated due to the inductance L of the motor, and the voltage drop due to the armature resistance Ra is also reduced slightly. That is, the voltage drop of the motor is reduced by the drop ΔVM (= Ec + Ra * ΔID). Here, ΔID represents a decrease in ID. The counter electromotive force Ec is obtained by Ec = L * ΔID / Δt. It is assumed that the motor speed does not change during one cycle of On / Off operation.

  The drain voltage VDS of T1 (which is equal to the drain-source voltage since the source is grounded) starts to increase due to the reduction ΔVM of the motor voltage drop. The gate-drain voltage of T1 is increased by ΔVM, and the gate-drain capacitance CGD is charged by ΔVM. Since the charge is supplied to the gate by this charge, the gate charge does not decrease even if the charge is discharged through R32. Therefore, the gate-source voltage VGS substantially does not decrease. This is the Miller effect.

  When the discharge through R32 continues, VDS increases. When the reference voltage VH is exceeded, T31 is turned off, a current flows from the power supply voltage VB to the gate of T1 via the resistors R31 and R32, and the gate starts to be charged. When the gate-source voltage VGS starts to increase due to the charging of the gate, the ID increases, and the gate charge is absorbed by the Miller effect as in the case of the gate charge discharge. For this reason, the gate-source voltage VGS hardly changes substantially. That is, the charge charged via R31 and R32 is canceled by the Miller effect. As the charging of the gate proceeds, VDS decreases, and when it falls below the reference voltage VL, the CMP3 output becomes L and T1 enters an OFF state.

  The amount of charge that supplies or cancels the charge to the gate of T1 by the Miller effect is determined by the reference voltages VL and VH, and is a constant amount. The time required for the gate circuit to charge and then discharge this amount of charge is one cycle of the On / Off operation. The gate charging time is determined by the power supply voltage and the gate resistance R31 + R32, and the discharging time is determined by the gate resistance R32. That is, the cycle of the On / Off operation is determined by the reference voltages VL and VH, the power supply voltage VB, and the gate resistors R31 and R32. Therefore, the cycle of the On / Off operation can be changed by changing the resistance R32 more specifically than the gate resistance.

3. 3. Description of the pinch detection circuit 6 3-1. Circuit Configuration of Pinching Judgment Circuit 6 The pinching judgment circuit 6 of FIG. 5 can be constituted by a 16-pulse counter whose input terminal is connected to the output terminal of CMP3 of the current limiting circuit 7 and resets unless counting for 80 μsec.

3-2, Description of Operation of Pinching Determination Circuit 6 The power window pinching prevention device detects pinching by the current detection circuit 2, limits the current by the current limiting circuit 7 and keeps the motor current ID within a certain range, and then determines whether the pinching has occurred. It is determined whether or not the circuit 6 is caught. The determination method will be described. When the motor rotation speed decreases due to the pinching, the On / Off operation period of T1 becomes longer and the continuous On period of T1 becomes shorter. Using this characteristic, it is determined whether or not the object is caught. There are the following three specific determination methods.

  (A) When the ratio between the continuous On period and the On / Off operation period is detected and reaches a certain value, it is determined that the jamming has occurred. The continuous On period and On / Off period can be determined by the CMP2 output. If the output of CMP2 is H level, it is continuous On, and if it is L level, it is an On / Off operation. Therefore, the target ratio can be detected by averaging the output of CMP2 as an analog signal.

  (B) The continuous On period or the On / Off operation period is timed, and when it reaches a certain value, it is determined that there is a pinch. The determination is made by measuring the H period or L period of the output of CMP2.

(C) Count the number of On / Off within the On / Off operation period, and when it reaches a certain value, it is determined that the jamming has occurred. As shown in FIG. 5, the number of rises of the output level of CMP3 is counted, and in the example of FIG. At this time, the counter is reset when the pulse is interrupted for a certain period so as not to be counted including the period of continuous On. In the example of FIG. 5, the counter is reset if the CMP3 output does not change for 80 μs. The rotation speed when it is determined that the jamming has occurred is set to a state in which the rotation speed is reduced by about 60% from the rotation speed before the jamming has occurred. This set value is a level at which a drop in the rotational speed due to a shock load fluctuation occurring on a rough road or the like does not occur.
● Setting method for pinching judgment value The setting method for pinching judgment value is summarized as follows.

  (I) A judgment value is set at a level that does not occur when the motor speed drops due to shock load fluctuations that occur on rough roads.

  (Ii) Since the duration of the On / Off operation depends on the OFF delay time of T1 and the responsiveness of the operational amplifier used for CMP1, the number of On / Off times corresponding to the above judgment value is set assuming the standard values of these characteristics. And set the counter value.

(Iii) When it is necessary to adjust the judgment value due to variations in the off delay time of T1 and the operational amplifier response, the on / off operation cycle is changed by changing the gate series resistance of T1 to reduce these variations. deal with. Even if the OFF delay time of T1 and the response of the operational amplifier vary, this makes it possible to fix the counter value.
● Change in motor rotation speed during On / Off operation It has been explained that the On / Off operation period becomes longer and the continuous On period becomes shorter due to a decrease in the motor rotation speed. That is, it is an assumption that the motor rotation speed hardly changes in one cycle of the On / Off operation. This is achieved by a method in which the motor keeps pressing the glass with a constant force even during the On / Off operation. Since the voltage between the motor terminals during the On / Off operation is VB-VDSonoff, Equation 14 is obtained when the motor output is Pm.

Pm = (VB-VDSonoff) * ID-Ra * ID2
= (VB-VDSonoff-Ra * ID2) * ID
= (Emotor-Eonoff) * ID ... Formula 14
From Equation 14, the following can be understood.

  (I) During the On / Off operation, the motor outputs a substantially constant output regardless of the rotational speed.

  (Ii) In the On / Off operation, the output decreases by VDSonoff * ID from the continuous On state.

  That is, the motor outputs a constant output and drives the window glass even during the On / Off operation. This means that the window glass is being pushed and the motor speed is always linked to the speed of the window glass. Since the movement of the wind glass is slow, it hardly changes in the On / Off cycle. Therefore, the motor rotation speed hardly changes in the On / Off1 cycle, and the assumption is valid.

Next, an example in which a part of the configuration of the power window pinching prevention device of the above example is changed will be described. FIG. 9 shows a circuit diagram of the device. Compared with the above example, the current following circuits 3 and 14 are different. The current follower circuit 14 removes the second charge / discharge circuits R22 and C2 from the current follower circuit 3, removes the resistor R28 that couples the non-grounded side of C1 and C2, and the first charging circuit is associated with this change. In order to maintain this time constant, the resistance value of the resistor R21 is changed. Further, the domain of the transistor T21 is directly connected to the power source VB, not the reference resistor R20, and further the resistor R26 connected to the positive input terminal of CMP1, the drain connected to the resistor R26, the source grounded, and the gate connected A transistor T23 connected to the output terminal of CMP2 is added.
● Description of Operation The motor current ID is converted into a voltage by the shunt resistor R1. Since CMP1 controls the positive input terminal voltage and the negative input terminal voltage to be always equal, the current Iref flowing through the reference resistor R20 is proportional to ID, and Iref * n = ID. Therefore, if the amount of change in Iref when the motor current ID changes by ΔID is ΔIref, ΔIref * n = ΔID.

  When pinching does not occur, the transistor T23 is on, so that the current component Iref-2 of Iref flows through R26 and T23. That is, Iref = Iref−f + Iref−2. Since Iref-2 cannot be changed, all Iref changes ΔIref are reflected in Iref-f, and a voltage change ΔVR24 expressed by Equation 15 occurs in the resistor R24 through which Iref-f flows.

ΔVR24 = ΔIref * R24 = (ΔID / n) * R24 Equation 15
When the ratio with the voltage change ΔVR1 (= ΔID * R1) generated in the shunt resistor R1 is taken, the voltage change at both ends of the shunt resistor R1 is amplified by 27.3 times as shown in Expression 16, and the resistance R24 It can be seen that occurs.

ΔVR24 / ΔVR1 = (R24 / R1) / n = (1.5 kΩ / 34 mΩ) /1618=27.3 Equation 16
On the other hand, there is a potential difference between the forward voltage drop of the diode D21 and the gate-source voltage of the FET T22 between the output voltage of CMP1 and the non-ground potential of R24, but this potential difference can be regarded as a constant value. Therefore, the output change of CMP1 is equal to the change of the non-ground side potential of R24. Accordingly, the change in the non-ground side potential of the capacitor C1 is obtained by averaging the change ΔVR24 in the non-ground side potential of R24 with the time constant R21 * C1. The non-grounded potential of the capacitor C1 is reflected on the source of the transistor T21, that is, the plus input terminal of CMP2 except for the difference in DC voltage. On the other hand, the non-ground side potential of R24 is input to the minus input terminal of CMP2. However, a DC potential difference of 0.7 V corresponding to the forward voltage drop of the diode D21 is applied between the positive input terminal and the negative input terminal.

  When the above is arranged, the ID change ΔID is converted into ΔVR1 by the voltage conversion by the shunt resistor R1. ΔVR1 is amplified by 27.3 times to become ΔVR24, and is applied to the CMP2 minus input terminal. The current → voltage conversion rate (ΔVR24 / ΔID) at that time is expressed by Expression 17.

ΔVR24 / ΔID = 27.3 * R1 * ΔID / ΔID = 27.3 * 34 mΩ = 928 mV / A Equation 17
The motor current ID includes a pulsating current component. Assuming that the total amplitude of the pulsating current is 0.5 A, ΔVR24 includes a voltage fluctuation of 928 mV * 0.5 A = 464 mV. That is, since there is a fluctuation of one-sided amplitude ± 232 mV, when a voltage increase of 0.7V−0.232V = 0.468V occurs, the CMP2 output is inverted from the H level to the L level. That is, 0.468V is the pinching detection value. When 0.468V is converted to ID, 0.5A (= 0.468V / R24 * n) is obtained. When the ID increases by 0.5 A, the CMP2 output is inverted.

  When the CMP2 output becomes L level, the transistor T23 is turned off, and the current Iref-2 flowing through R26 and T23 disappears. Since ID does not change at this time, the reference current Iref does not change. For this reason, Iref-f increases by Iref-2, which disappears. As a result, the voltage drop of R24 increases and the negative input terminal voltage of CMP2 rises. The amount of increase is Iref-2 * R24. When the CMP2 output becomes L level, an On / Off operation starts and ID decreases. When the amount of decrease in Iref due to the decrease in ID exceeds Iref-2, CMP2 is inverted again to the H level, and ID is continuously turned on and starts increasing. When the CMP2 output becomes H level, T23 is turned on and Iref-2 flows, Iref-f decreases accordingly, and the CMP2 minus terminal voltage decreases by Iref-2 * R24. When the amount of increase in Iref due to the increase in ID exceeds Iref-2, CMP2 is inverted to the L level. Since the FET T1 has an off-delay when the CMP2 output becomes L level, the ID increases during this delay. Therefore, the ID of the CMP2 output must be decreased during the L period, including not only Iref-2 but also an increase in ID due to delay.

  The maximum value of the motor current ID during the current limiting period in which On / Off operation and continuous On are repeated is the average ID value before sandwiching plus the sandwich detection value 0.5A (0.468V), and the minimum current value is Iref- Determined by the size of 2. Therefore, the average ID value during the current limiting operation can be arbitrarily set by adjusting the value of Iref-2.

The above is the operation of the circuit of FIG. 9, and the differences from the circuit of FIG. 5 are summarized below.
(I) Iref-f in FIG. 5 is not a change in ID itself. ΔIref-f * n ≠ ΔID. The potential difference generated at both ends of the resistor R22 indicates that there is a deviation between ID and Iref. Therefore, the voltage drop ΔVR24 generated in the resistor R24 due to ΔIref-f does not accurately represent ΔID. Δ Sometimes greater than ID, sometimes smaller. That is, the amplitude of ΔVR24 is larger than that corresponding to ΔID. For this reason, the pinching determination value is substantially reduced, and the On / Off operation is easily started. This means that the chance of malfunctioning increases due to shock load fluctuations due to bad roads and the like.

On the other hand, in FIG. 9, ΔVR24 accurately represents ΔID, and there is no influence due to deviation from ΔID.
(Ii) In the circuit of FIG. 5, during the On / Off operation, the fluctuation of the output of CMP1 becomes large and becomes saturated at the H level and the L level. The CMP2 minus input terminal voltage has a large deviation from ΔID, which is different from the change in ID. The CMP2 plus input terminal voltage does not change, and even if the minus input terminal voltage is controlled in comparison with the plus input terminal voltage, ΔID does not coincide with the CMP2 minus input terminal voltage. Will increase.

On the other hand, in FIG. 9, since the change in the motor current is reflected in the CMP2 minus terminal voltage, the peak value during current control is kept constant.
(Iii) In FIG. 5, the duration of the On / Off operation is determined by the OFF delay of T1, the response delay of CMP1, and the motor speed. Of these, the influence of the response delay time of CMP1 is large. Although control using Iref-2 as shown in FIG. 9 is possible, there is a sufficient On / Off operation period even if Iref-2 = 0A. If Iref-2 is used, the On / Off operation period becomes too long. Then, it is not preferable. That is, the On / Off operation time cannot be controlled from the outside.

On the other hand, in FIG. 9, the delay of T1 and the rotational speed of the motor are the factors that determine the On / Off operation period as in FIG. 5, but the response delay of CMP1 does not affect. Furthermore, by using Iref-2, the On / Off operation period can be practically controlled to an arbitrary value. Increasing Iref-2 lengthens the On / Off operation period, and therefore the minimum value of ID can be lowered. Since the maximum value of ID at the time of current limitation is kept constant and the minimum value can be controlled, the average current value of ID at the time of current limitation can be set to a desired value.
(Iv) In FIG. 5, Iref-s which is a part of Iref flows in conjunction with C1. When pinching occurs and ID increases, the potential of C1 hardly increases, but is still not zero. Iref-s increases corresponding to the increase amount of the C1 potential, and the increase amount of Iref-f decreases accordingly. That is, the detection sensitivity is reduced accordingly. On the other hand, in FIG. 9, the increase in the C1 potential when pinching occurs is the same, but the increase in C1 is not related to Iref, so the increase in Iref-f is not suppressed by the increase in C1. Accordingly, there is no decrease in detection sensitivity due to an increase in the C1 potential, and more accurate control can be realized. As can be seen from the above facts, the circuit of FIG. 9 is superior to the method of FIG.

  In the circuit shown in FIG. 9 in the power window pinching prevention device described above, when pinching is detected even for a moment (CMP2 output is “L”), the current Iref-2 is obtained by turning off T23 in response to the signal. The current Iref-2 is cut off, and the current Iref-2 is added to the current component Iref-f of the reference current Iref for easy detection, and the current amount of the current Iref-2 can be adjusted by the resistor R26. However, since the current Iref-2 flows more than necessary or does not flow because it directly receives fluctuations in the power supply voltage, it may be pinched and erroneously detected or pinned.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power window pinching prevention device that detects the pinching of foreign matter by window glass from a change in motor current. It is an object of the present invention to provide an improved power window pinching prevention device that limits a motor current by quickly detecting current without misidentification.

In order to achieve the above-described object, a power window pinching prevention device according to the present invention is a power window pinching prevention device that detects the pinching of a foreign object by a window glass from a change in motor current. ,
A current detection circuit for detecting an increase in a motor current flowing through the power window motor; and a predetermined current according to a current limit control signal output from the current detection circuit when the increase amount of the motor current exceeds a predetermined value. A current limiting circuit that decreases and increases in range, and a pinching determination circuit that determines pinching from the increase in the motor current and reverses the power window motor,
The current detection circuit is connected in series to the power window motor and the current limiting circuit, and one end is connected to the ground terminal of the power supply device, and the motor current flows, and n times the shunt resistance A reference resistor having a resistance value, one end connected to the ground terminal of the power supply device, and connected to the other end of the reference resistor and connected to the other end of the shunt resistor, the shunt resistor and the reference resistor A current follower circuit that causes a follower current to flow through the reference resistor so that the voltage applied to each is always equal,
In the power window pinching prevention device,
The current follower circuit controls a follower current flowing through the reference resistor to be 1 / n of the motor current, and a pulsating component of the motor current generated by the follower current control circuit. A first comparator including a first reference voltage applied to one terminal, the other input terminal of the first comparator, and a plus terminal of the power supply device; A capacitor that generates a second reference voltage indicating an average value by charging and discharging and applies it to the other input terminal of the first comparator, and a first current for charging the capacitor connected in parallel to the capacitor A first semiconductor switch connected to the first current source and performing an On / Off operation according to an output of the first comparator, and the first semiconductor switch A second current source for discharging the capacitor connected to the first current source via the H and connected between the first semiconductor switch and a ground terminal of the power supply device; And a charge / discharge circuit having
In the current detection circuit, a third reference voltage generated by the following current control circuit and having a predetermined voltage value higher than the first reference voltage is applied to one input terminal, and the second reference voltage is applied to the other A second comparator applied to the input terminal and outputting the current limit control signal from the output terminal; and
The circuit is connected between a circuit portion from which the third reference voltage is obtained and a ground terminal of the power supply device, and is fixed from the circuit portion from which the third reference voltage is obtained by stabilized voltage supply from the stabilized power supply device. Depending on the presence or absence of the current limiting control signal from the second comparator via the digital filter, a constant current circuit for flowing current, a digital filter for removing an instantaneous output change component from the output of the second comparator A second semiconductor switch that performs an On / Off operation and performs On / Off of the constant current circuit, and the second semiconductor switch is operated while the current limit control signal is not output from the second comparator. The constant current circuit is operated in an on state, and the second semiconductor switch is in an on state while the current limit control signal is output. Characterized by the Kijo current circuit in a stopped state.

  According to the first aspect of the present invention, when the current detection circuit is in a normal state where no pinching has occurred, the constant current circuit is operated to obtain the third reference voltage from the circuit portion toward the ground terminal of the power supply device. When a certain amount of current is shunted and pinching occurs, the motor current increases and the current limit control signal is output from the second comparator, the operation of the constant current circuit is stopped and the third reference voltage is Stop shunting from the resulting circuit portion. When the motor current increases due to pinching, the amount of current flowing through the circuit part where the third reference voltage is obtained decreases, so by stopping the shunting from the circuit part where the third reference voltage is obtained, Therefore, the amount of current flowing through the circuit portion where the third reference voltage can be obtained increases. Thereafter, when pinching does not occur, a certain amount of current is shunted from the circuit portion where the third reference voltage is obtained. Therefore, it is possible to change the amount of current flowing through the circuit portion from which the third reference voltage is obtained without being affected by fluctuations in the power supply voltage, and compared with a conventional circuit that is easily affected by fluctuations in the power supply voltage. It is possible to eliminate pinching erroneous detection and pinching detection failure.

  In addition, since a component such as noise that temporarily changes the output is removed from the output of the second comparator by the digital filter, it is possible to prevent erroneous detection by being sandwiched by an instantaneous increase in motor current. it can.

  The power window pinching prevention device according to claim 2 is the power window pinching prevention device according to claim 1, wherein the current detection circuit is provided between the positive terminal of the power supply device and the constant current circuit. A resistor and a constant voltage diode connected in series are further provided, and when the output of the power supply device becomes a high voltage, a current having a value adjusted by the resistor via the constant voltage diode is supplied to the constant current circuit. It is characterized by flowing.

  According to the second aspect of the present invention, when the output of the power supply device becomes a high voltage, the current detection circuit passes a current having a value adjusted by a resistor through the constant voltage diode to the constant current circuit. Since the amount of current flowing through the circuit portion where the third reference voltage is obtained at high voltage increases, pinching at high voltage can be reliably detected. That is, the load value can be reduced by being sandwiched.

  As described above, according to the present invention, when pinching is detected, the amount of the current component of the reference current flowing through the circuit portion where the third reference voltage is obtained is increased. Since the current source for reducing the current amount of the current component is made constant, the amount of current flowing through the circuit portion where the third reference voltage can be obtained is changed by a certain amount even if the power supply voltage fluctuates. Compared with the conventional circuit that is easily affected by fluctuations in the power supply voltage, it is possible to eliminate pinching and false detection or pinching detection failure.

  In addition, since the digital filter removes a component that instantaneously changes its output, such as noise, from the output of the second comparator, it is possible to prevent erroneous detection by being sandwiched by an instantaneous increase in motor current.

  Further, since the current component of the reference current flowing through the circuit portion where the third reference voltage can be obtained at high voltage is further increased, pinching can be detected in a short time, and pinching load at high voltage can be reduced. .

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments according to the invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a circuit diagram schematically showing a power window pinching prevention device according to a first embodiment of the present invention.

  The power window pinching prevention device of the present embodiment shown in FIG. 1 arranges the shunt resistor R1 and the reference resistor R20 of the current detection circuit 2 shown in FIG. 9 on the low side (that is, the ground side) of the power window motor 5, and this Accordingly, the circuit configuration of the current tracking circuit 14 of the current detection circuit 2 is changed, and a tracking current changing circuit that changes the value of the tracking current when the pinching is further detected by such a circuit and when it is not detected. 15 has been added. Details of the follow-up current changing circuit 15 will be described later.

  As shown in FIG. 1, the power window pinching prevention device of the present embodiment includes a current detection circuit 2 a that detects an increase in motor current ID flowing in a power window motor 5 having a normal rotation and inversion circuit, and a motor current ID. A current limiting circuit 7 that decreases and increases the motor current ID within a predetermined range according to the current limiting control signal CPOUT_B output from the current detection circuit 2a when the increase amount exceeds a predetermined value, and the current limiting circuit 7 and the power window And a pinching determination circuit 6 that is connected to the motor 5 and determines pinching from the increase of the motor current ID and reverses the power window motor 5. The configuration of the power window motor 5, the jamming determination circuit 6 and the current limiting circuit 7 is practically the same as the circuit configuration of the power window jamming prevention device of FIG.

  The current detection circuit 2a is connected in series to the power window motor 5 and the current limiting circuit 7, and has one end connected to the negative terminal (ground terminal; ground) of the power supply device VB and a shunt resistor R1 through which the motor current ID flows. The reference resistor R20 has a resistance value n times that of the shunt resistor R1, one end is connected to the negative terminal of the power supply device VB, and the other end of the reference resistor R20 is connected to the other end of the reference resistor R20. Is connected to the shunt resistor R1 and the reference resistor R20 so that the voltage applied to each of the reference resistor R20 is always equal to each other. A comparator whose output terminal is connected to NOR1 (see FIG. 9) of the current limiting circuit 7 A second comparator) CMP2, connected between the output terminal of the 5V power supply and CMP2 has a current limiting control signal CPOUT_B a pull up resistor R25, and.

  The current follower circuit 14a controls the follower current flowing through the reference resistor R20 to be 1 / n of the motor current ID (that is, the follower current so that the voltages applied to the shunt resistor R1 and the reference resistor R20 are always equal). (Following current to the reference resistor R20). The follow-up current limiting circuit includes a resistor R24 having one end connected to the electric wire 1, and a resistor R27 having one end connected to the other end of the resistor R24 and a plus input terminal of CMP2 connected to the connecting line to the resistor R24. A FET T22 provided between the resistor R27 and the reference resistor R20 so that the drain terminal is connected to the other end of the resistor R27 and the source terminal is connected to the other end of the reference resistor R20, and the source of the T22 An operational amplifier AMP1 having a positive input terminal connected to the terminal and an output terminal connected to the gate terminal of T22, one end connected to the negative input terminal of the operational amplifier AMP1, and the other end connected to the other end of the shunt resistor R1. A resistor R29, a resistor R23 having one end connected to the electric wire 1, and an emitter terminal connected to the other end of the resistor R23; A PNP bipolar transistor T23 whose collector terminal is connected to the source terminal of the FET T22, a negative input terminal connected to the emitter terminal of the T23, an output terminal connected to the base terminal of T23, and a positive input terminal CMP2 And an operational amplifier AMP2 connected to the negative input terminal.

  The operational amplifier AMP1 is appropriately connected from the output terminal to the gate terminal of the FET T22 so that the current component Iref-f of the reference current Iref flows from the FET T22 to the reference resistor R20 according to the increase or decrease of the motor current ID flowing through the shunt resistor R1. Control by applying voltage. In this control, when the motor current ID increases, the input terminal voltage of the AMP1 increases, so that the voltage applied from the AMP1 to the gate terminal of the FET T22 increases, and a large amount of current Iref-f flows. When ID decreases, the input terminal voltage of AMP1 decreases, so the voltage applied from AMP1 to the gate terminal of FET T22 decreases and current Iref-f decreases.

  The current tracking circuit 14a further includes a comparator (first comparator) in which the negative input terminal is connected to the positive input terminal of the operational amplifier AMP2 and the positive input terminal is connected to the drain terminal of the FET T22 (that is, the other end of the resistor R27). ) CMP1 and a charge / discharge circuit. The charging / discharging circuit includes a capacitor C1 having one end connected to the electric wire 1 and the other end connected to the negative input terminal of CMP1, a parallel connection with the capacitor C1, and a first input terminal connected to the electric wire 1. Current source AS1, a semiconductor switch SSW1 connected to the output side terminal of the current source AS1 and operating on / off according to the output of CMP1, an input side terminal connected to the semiconductor switch SSW1, and an output side terminal supplying power And a second current source AS2 connected to the negative terminal of the device VB.

  In the current tracking circuit 14a, the first reference voltage Vc2 that is the potential of the drain terminal of the FET T22 (that is, the other end of the resistor R27) is applied to the plus input terminal of the comparator CMP1. Further, the second reference voltage Vc is generated by charging / discharging of the capacitor C1 and controlled to be an average value of the first reference voltage Vc2, and is applied to the minus input terminal of CMP1 and the minus input terminal of CMP2. The third reference voltage Vins applied to the positive input terminal of CMP2 has a voltage value higher than Vc2 by the amount of the resistor R27.

  The operational amplifier AMP2 is obtained by dividing the voltage (that is, the differential voltage between the electric potential of the electric wire 1 and Vc) applied to both ends of the resistor R23 by the current value of the current component Iref-s of the reference current Iref by the resistance value of the resistor R23. Therefore, an appropriate voltage is applied from the output terminal to the base terminal of T23, and T23 is controlled so that the current Iref-s flows through the resistor R23. In this control, when the motor current ID increases, the input terminal voltage (Vc) of AMP2 decreases, so the voltage applied from AMP2 to the base terminal of T23 decreases, and a large amount of current Iref-f flows, and conversely When the current ID decreases, the input terminal voltage (Vc) of AMP2 increases, so the voltage applied from AMP2 to the base terminal of T23 increases and current Iref-f decreases.

  The reference resistor Iref flowing through the reference resistor R20 is the sum of the current component Iref-f flowing through the resistor R24 and the resistor R27 and the current component Iref-s flowing through the resistor R23, and is similar to the case of the circuit configuration of FIG. 5 or FIG. The current corresponds to several thousand to several ten thousandths of the motor current ID, and pulsates similarly to the motor current ID. The third reference voltage Vins indicates the potential between the resistor R24 and the resistor R27, and the potential dropped from the Vins by the resistor R27 by a certain value is Vc2, so that Vc2 also pulsates in the same manner as Vins. To do.

  In the power window pinching prevention device shown in FIG. 1, when pinching occurs and the motor current ID rapidly increases, the positive input terminal voltage of CMP2 (that is, the third reference voltage Vins) indicating the instantaneous value of the motor current ID and the capacitor C1 And the negative input voltage (Vc) of CMP2 generated by charging / discharging of CMP2 and the output (CPOUT_B) of CMP2 changes from H level to L level during this crossing. When CPOUT_B becomes the L level, the semiconductor switching element T1 (see FIG. 9) is turned on / off in the current limiting circuit 7, and the determination circuit 6 inserts the number of on / off times in the on / off operation period to determine the current. Counting is performed based on the number of rises in the output level of CMP3 (see FIG. 9) of the limiting circuit 7, and if it reaches a certain value (for example, 16 pulses), it is determined that it is pinched.

  The tracking current changing circuit 15 includes a digital filter FIL having an inverting input terminal connected to the output terminal of CMP2, a resistor R203 having one end connected to a plus terminal of a stabilized power supply device (not shown), a collector, and a base. An NPN transistor T30 commonly connected to the other end of the resistor R203, a resistor R204 having one end connected to the emitter of the transistor T30 and the other end connected to the negative terminal of the power supply device VB, and a collector connected to the resistor R24 An NPN-type transistor T31 connected to the connection portion with the resistor R27 and having a base connected to the base of the transistor T30, one end connected to the emitter of the transistor T31, and the other end connected to the negative terminal of the power supply device VB. The resistor R205 and the gate are connected to the output terminal of the digital filter FIL and Including in-is connected to the negative terminal of the transistor T30 and T31 more source power supply device VB is connected to the respective bases FETT32, the.

  The transistors T30 and T31 and the resistors R203 to R205 constitute a so-called current mirror constant current circuit, and a current having the same value as the current Iref-f2 flowing through this circuit is supplied from the connecting portion of the resistor R24 and the resistor R27 to the power supply device VB. It flows toward the negative terminal. That is, a current corresponding to the current Iref-f2 out of the current Iref-f flowing through the resistor R27 is shunted to the constant current circuit side. However, the condition is that the FET T32 is turned off.

  The FET T32 is turned on / off in accordance with the change in the output (F_CPOUT) level of the digital filter FIL. That is, at the normal time when pinching does not occur, the output of the comparator CMP2 is at the H level and the output of the digital filter FIL (F_CPOUT) is at the L level, so the FET T32 is in the off state. In this state, since the constant current circuit is in an operating state, a current corresponding to the current Iref-f2 is shunted from the connection portion of the resistor R24 and the resistor R27. On the other hand, when pinching occurs and the motor current ID increases, the comparator CMP2 changes from the H level to the L level, and the output (F_CPOUT) of the digital filter FIL changes to the H level accordingly, so that the FET T32 is turned on. In this state, since the bases of the transistors T30 and T31 of the constant current circuit are connected to the negative terminal of the power supply device VB, the constant current circuit is stopped, and thereby the current Iref-f2 is a resistance. It will flow to R27. That is, the current Iref-f2 serves as a hysteresis that changes the current amount of the current Iref-f by a certain amount depending on H / L of the output level of the digital filter FIL.

  In the conventional circuit shown in FIG. 9, the current amount of the current Iref-2 can be adjusted by adjusting the resistance value of the resistor R26. However, since the power supply is taken from the power supply device VB, As a result, current may flow more or less than necessary in the resistor R24, and it may be pinched and erroneously detected or pinned. In that respect, in the present invention, by using a constant current circuit, a constant amount of current can be flowed regardless of the power supply voltage, and therefore, there is no possibility of being pinched and erroneously detected or undetectable.

  Further, in the conventional circuit shown in FIG. 9, when the output of the comparator CMP2 becomes L level, the transistor I23 is turned off in response to the signal to cut off the current Iref-2. However, when the output of the comparator CMP2 becomes L level even for a moment, the transistor T23 is turned off, so that even the noise is detected. Sometimes. In that respect, in the present invention, the digital filter FIL removes the instantaneous change in output from the output of the comparator CMP2, so that it is not detected that it is pinched by something like noise.

  Thus, according to the first embodiment of the present invention, the amount of current component Iref-f of reference current Iref is increased when pinching is detected, and current component Iref-f otherwise. Since the current source for reducing the current amount is made constant so as not to be affected by fluctuations in the power supply voltage, and the instantaneous output change is removed from the output of the comparator CMP2, erroneous detection or It is possible to reliably detect pinching without being detected.

  Next, FIG. 2 is a configuration diagram of a constant current circuit of a power window pinching prevention device according to a second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the part which is common in the constant current circuit of FIG.

  The power window pinching prevention device of the present embodiment shown in FIG. 2 includes a resistor R206 and a constant voltage diode between the positive terminal of the power supply device VB and the bases of the transistors T30 and T31 in the constant current circuit of the first embodiment. The structure which connected D41 in series is taken. By inserting a resistor R206 and a constant voltage diode D41 connected in series to the relevant part of the constant current circuit, the constant voltage circuit is fixed when the output of the power supply device VB becomes high, that is, when the output voltage becomes high (eg, 14.5 V). A current Iref-f20 having a current value adjusted by the resistor R206 flows through the voltage diode D41 to the constant current circuit. As a result, a current Iref-f incremented by a current obtained by adding the currents Iref-f2 and Iref-f20 flows through the resistor R27. By increasing the hysteresis current in this manner, pinching can be detected in a short time, and the pinching load at high voltage can be reduced. In the conventional circuits of FIGS. 5 and 9, since the control method is not changed at the time of high voltage, the load is increased by being sandwiched at the time of high voltage. The present invention can solve this problem.

  In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably. In addition, the form, number, arrangement location, and the like, the numerical value, the waveform, and the like of each component in the above-described embodiment are arbitrary and are not limited as long as the present invention can be achieved.

It is a circuit diagram showing typically the power window pinching device which is the 1st embodiment concerning the present invention. It is a circuit diagram which shows the constant current circuit of the power window clamping apparatus which is 2nd Embodiment based on this invention. It is a block diagram of the conventional power window pinching prevention device. It is a block diagram for demonstrating the modification of the conventional power window pinching prevention apparatus. It is a circuit diagram of the conventional power window pinching prevention device. It is a figure for demonstrating the On / Off operation | movement of the current detection circuit of the conventional power window pinching prevention apparatus. It is the static characteristic figure which added the load line for demonstrating operation | movement of the semiconductor switching element of the current limiting circuit of the conventional power window pinching prevention device. It is an equivalent circuit diagram for demonstrating operation | movement of the semiconductor switching element of the current limiting circuit of the conventional power window pinching prevention apparatus. It is a block diagram of the other conventional power window pinching prevention apparatus.

Explanation of symbols

5: Power window motor ID: Motor current 2a: Current detection circuit CPOUT_B: Current limit control signal 7: Current limit circuit 6: Pinch determination circuit VB: Power supply device R1: Shunt resistor R20: Reference resistor 14a: Current tracking circuit 15 : Following current changing circuit Vc2: first reference voltage CMP1: first comparator Vc: second reference voltage C1: capacitor AS1: first current source SSW1: semiconductor switch AS2: second current source Vins: third reference voltage CMP2: second comparator FIL: digital filter R203 to R205: resistance T30, T31: transistor T32: FET

Claims (2)

A power window pinching prevention device that detects pinching of foreign matter by window glass from a change in motor current,
A current detection circuit for detecting an increase in a motor current flowing through the power window motor; and a predetermined current according to a current limit control signal output from the current detection circuit when the increase amount of the motor current exceeds a predetermined value. A current limiting circuit that decreases and increases in range, and a pinching determination circuit that determines pinching from the increase in the motor current and reverses the power window motor,
The current detection circuit is connected in series to the power window motor and the current limiting circuit, and one end is connected to the ground terminal of the power supply device, and the motor current flows, and n times the shunt resistance A reference resistor having a resistance value, one end connected to the ground terminal of the power supply device, and connected to the other end of the reference resistor and connected to the other end of the shunt resistor, the shunt resistor and the reference resistor A current follower circuit that causes a follower current to flow through the reference resistor so that the voltage applied to each is always equal,
In the power window pinching prevention device,
The current follower circuit controls a follower current flowing through the reference resistor to be 1 / n of the motor current, and a pulsating component of the motor current generated by the follower current control circuit. A first comparator including a first reference voltage applied to one terminal, the other input terminal of the first comparator, and a plus terminal of the power supply device; A capacitor that generates a second reference voltage indicating an average value by charging and discharging and applies it to the other input terminal of the first comparator, and a first current for charging the capacitor connected in parallel to the capacitor A first semiconductor switch connected to the first current source and performing an On / Off operation according to an output of the first comparator, and the first semiconductor switch A second current source for discharging the capacitor connected to the first current source via the H and connected between the first semiconductor switch and a ground terminal of the power supply device; And a charge / discharge circuit having
In the current detection circuit, a third reference voltage generated by the following current control circuit and having a predetermined voltage value higher than the first reference voltage is applied to one input terminal, and the second reference voltage is applied to the other A second comparator applied to the input terminal and outputting the current limit control signal from the output terminal; and
The circuit is connected between a circuit portion from which the third reference voltage is obtained and a ground terminal of the power supply device, and is fixed from the circuit portion from which the third reference voltage is obtained by stabilized voltage supply from the stabilized power supply device. Depending on the presence or absence of the current limiting control signal from the second comparator via the digital filter, a constant current circuit for flowing current, a digital filter for removing an instantaneous output change component from the output of the second comparator A second semiconductor switch that performs an On / Off operation and performs On / Off of the constant current circuit, and the second semiconductor switch is operated while the current limit control signal is not output from the second comparator. The constant current circuit is operated in an on state, and the second semiconductor switch is in an on state while the current limit control signal is output. Power window jamming preventing apparatus characterized by the Kijo current circuit in a stopped state. The current detection circuit further includes a resistor and a constant voltage diode connected in series between the positive terminal of the power supply device and the constant current circuit, and when the output of the power supply device becomes a high voltage, 2. The power window pinching prevention device according to claim 1, wherein a current having a value adjusted by the resistor is caused to flow through the constant current circuit through the constant voltage diode.

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