JPS6326639B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a load drive device suitable for application to, for example, an automatic window glass lifting control device for automobiles, which is usually called a one-touch power window.

Conventionally, in this type of device, for example, a window glass automatic lift control device, once the operating switch is operated, a self-holding circuit is activated and the window glass continues to operate even if the operating switch is released, and when the operating switch is fully closed or fully opened, the window glass is self-holding. The circuit seems to be released. Various methods for detecting fully closed and fully opened states have been known. An example of this is to incorporate a pulse generator into the motor that generates pulses proportional to the motor rotation speed and take advantage of the fact that no pulses are generated when the motor is fully closed or fully open, or the motor current includes ripples while the motor is rotating. A method is known that takes advantage of the fact that ripples disappear when the lock is fully closed or fully open.

However, with conventional methods, it is necessary to incorporate a pulse generator into the motor or use a transformer to extract only the ripples of the motor current, which poses a major obstacle to reducing the size and weight of control devices. was.

Therefore, in the present invention, the window glass is fully closed and fully opened,
Focusing on the fact that when the motor is locked, a lock current that is several times as large as when it is in operation flows through the motor, and this is detected to make a lock (overload) determination. However, when such a lock detection method is used, the following problems may occur.
Suppose the operating current of the motor is 5A and the lock current is
Assuming that the current is 30A and the set current for releasing the self-holding circuit is 10A, the control device will operate for the time being. However, since the motor current and the motor output shaft torque are generally in a proportional relationship, the above settings
Even though the motor is capable of producing shaft torque equivalent to 30A, it can only utilize shaft torque equivalent to 10A. However, the set current value is close to 30A.
If it is set to 25A, if the environmental temperature or power supply voltage fluctuates, the lock current may fluctuate and fall below the set current value of 25A, making it impossible to release the self-holding circuit. For this reason, in the present invention, even if there are fluctuations in the surrounding environmental temperature and power supply voltage, the motor lock is determined based on the load current, and the self-holding of energization to the DC motor is reliably and stably released. The object of the present invention is to provide a load drive device for a vehicle that can accurately automatically stop a motor, effectively utilize the shaft torque of the motor, and prevent burnout of the motor due to overcurrent when the motor is locked. shall be.

The details of the present invention will be explained below using an embodiment shown in the drawings. In the attached diagram, 1 is an operation switch, which has a neutral point N shown by a solid line, and operation positions of up U, down D, up hold UH, and down hold DH,
Normally, the structure is such that it self-returns to the neutral point N shown in the figure. Reference numeral 2 denotes a two-brush type DC motor that raises and lowers a window glass (not shown) as a load using gears, a crank mechanism, etc., and includes a normally closed bimetal switch 2a and a motor body 2b. 3 is a window glass automatic lift control device according to the present invention. 4 is an on-vehicle DC power supply.

In the control device 3, RL ₁ and RL ₂ are for rising, respectively.
This is a descending relay. Transistors Tr ₁ , Tr ₂ and resistors R ₈ , R ₉ , R ₁₀ , R ₁₄ , R ₁₅ constitute a self-holding circuit on the rising side; transistors Tr ₃ , Tr ₄ and resistors R ₁₁ , R ₁₂ ,
R ₁₃ , R ₁₆ , and R ₁₇ constitute a descending side self-holding circuit.

Resistor R ₂₀ is a microresistance for current detection, IC ₁ and IC ₂ are comparators, and the output stage has an open collector transistor structure with a grounded emitter. Further, both comparators IC ₁ and IC ₂ constitute a window comparator, and the output becomes the ground level when the input voltage is lower than the lower reference voltage VL or higher than the upper reference voltage VH.

Resistors R ₂ , R ₃ , R ₄ , R ₅ , diode D ₂ , and Zener diode D ₃ constitute a reference voltage generation circuit. This reference voltage changes depending on temperature and DC power supply. In other words, by utilizing the fact that the forward voltage of diode D ₂ changes with temperature, the reference voltages VL and VH become low when the temperature is high, and when the power supply is high through Zener diode D ₃ and resistor R ₃ , the reference voltage becomes high. It's starting to happen. These reference voltage setting elements are matched with the temperature and voltage characteristics of the motor lock current, and in any case the upper reference voltage VH is smaller than the voltage drop that the motor lock current is converted by the microresistance _R20 . It's becoming like that. Resistance R ₇ ,
The diode _D1 constitutes a constant voltage circuit, and a bias current is passed through the diode _D2 through a resistor _R1 .

The diodes D ₄ and D ₅ have a wraparound prevention function so that when one self-holding circuit is activated, the other self-holding circuit is not activated. Capacitor C ₂ ,
_C3 is for preventing the self-holding circuit from malfunctioning due to noise or the like. diode
For D ₆ and D ₉ , press operation switch 1 to raise U or lower D
This is to prevent wraparound, so that when only relays RL ₁ and RL ₂ are activated when the self-holding circuit is operated, only relays RL ₁ and RL ₂ are activated and the self-holding circuit is not activated. The diodes D ₇ and D ₈ are for absorbing the surge current of the relays RL ₁ and RL ₂ and protecting the semiconductor elements. The resistances R ₁₈ and R ₁₉ are
Hold operation switch 1 up (UH) or down (hold down)
If the voltage at the power terminal of the operating switch 1 becomes higher than the power terminal of the control device 3 due to a voltage drop on the wiring when operated to DH, the transistor Tr ₁ ,
This is for the current side limit that protects Tr ₂ from overcurrent.

The capacitor C ₁ and the resistor R ₆ form a filter circuit that removes high frequency components from the voltage drop that occurs across the detection resistor R ₂₀ due to the load current flowing through the motor 2. The connection point between the capacitor C ₁ and the resistor R ₆ A voltage stably corresponding to the load current flowing through the motor 2 is generated.

In the above configuration, the operation is controlled by the switch 1.
The following describes the operations.

(1) Raising operation, lowering operation When operating switch 1 is moved to the raising position U,
Relay RL ₁ is energized and motor 2 is operated upward by the current shown by arrow Iu, and when operation switch 1 is released, relay RL ₁ is deenergized and motor 2 is stopped. The lowering operation is also the same, and operation switch 1
One of the relays RL ₁ and RL ₂ is energized only while the window is being operated to the raised position U or the lowered position D, and during that time the window glass is raised or lowered by the motor rotation.

(2) Up hold operation, down hold operation When operation switch 1 is operated to the up hold position UH, relay RL ₁ is energized and motor 2 begins to operate in the up direction by the current shown by arrow Iu, and the motor current decreases to several Become A. Therefore, the comparison input voltage V _I of window comparators IC ₁ and IC ₂ is the reference voltage V _L
Since the output voltage V _A is larger, the output voltage V A is in an open state, so the self-holding circuit on the rising side is activated and the transistors Tr ₁ and Tr ₂ are turned on, so even if the operating switch 1 is released, the relay RL ₁ remains The motor 2 continues to be energized and continues to rotate in the upward direction. However, when the window glass is fully closed, the load resistance increases rapidly, so a lock current flows through motor 2, and the comparison input voltage of the window comparator increases.
Since V _I is larger than the reference voltage V _H and therefore the output voltage V _A is at ground level, the transistor
The bias of Tr ₂ is cut off and the self-holding circuit is released. Therefore, relay RL ₁ is deenergized and motor 2
Power supply to is stopped. The operation when the operation switch 1 is set to the lower holding position DH is the same as above, and the energization of the relay RL ₂ is maintained by turning on the transistors Tr ₁ and Tr ₂ until the window glass is fully opened. .

(3) Stop during rising holding operation or falling holding operation, as mentioned in (2) above, during rising holding operation, the output voltage V _A of the window comparator is in the open state, the rising side self-holding circuit is activated, and relay RL ₁
is in an energized state, and the motor 2 is rotating in the direction of raising the window glass. At this time, when the operation switch 1 is operated for a short time to the lowering side, the lowering side relay RL ₂ is also energized, both brushes of the motor 2 are short-circuited, and the power supply is stopped, and the motor is stopped at this point. At this time, the motor current becomes 0, so after an extremely short period of time determined by the time constants of the filter circuits C ₁ and R ₆ , the output voltage of the window comparator V _A becomes the ground level, and the self-holding circuit on the rising side is released. , only relay RL ₁ is de-energized. Therefore, the motor 2 attempts to rotate instantaneously in the downward direction, but the operator releases the control switch 1 within a short period of time.
Relay RL ₂ on the lowering side is also deenergized, power supply to motor 2 is stopped, and the window glass is stopped at that position.
Stopping during the downward hold operation is also the same as above.

In the above-described embodiment, the temperature characteristic of the forward voltage of the diode was used as a method of imparting temperature characteristics to the set current value, but it is also possible to use other temperature sensing elements such as a thermistor. Furthermore, when using a voltage comparison circuit such as the comparators Ic ₁ and Ic ₂ , the temperature characteristics and voltage characteristics are made to act on the comparison input voltage _VI instead of the reference voltages V _L and V _H , and the relative relationship between the two voltages is determined. Temperature characteristics and voltage characteristics may be added to the voltage characteristics. Furthermore, the present invention is applicable not only to a window glass automatic lift control device but also to a sump opening/closing control device and the like.

As described above, the present invention detects the lock current of the motor to release the self-holding state, and there is no need to incorporate a special device into the motor to detect whether or not the motor is rotating. A motor can be used and the control device can be made small and lightweight. In addition, either the detection signal corresponding to the load current or the setting signal corresponding to the load current (lock current) when the motor is locked,
Since it is compensated by voltage, even if the surrounding environment temperature and power supply voltage fluctuate and the load current changes when the motor locks, the DC motor may be stopped before the motor locks, or after the motor locks. This also prevents problems that would occur if the DC motor is energized, makes it possible to effectively utilize the shaft torque that the DC motor can generate, and prevents burnout of the DC motor due to overcurrent after the motor locks.

[Brief explanation of the drawing]

The accompanying drawings are electrical circuit diagrams showing one embodiment of the present invention. 1... Operation switch as a command means, 2...
DC motor, 3...Window glass automatic lift control device,
4... Vehicle-mounted DC power supply, IC ₁ , IC ₂ ... Comparators forming a window comparator as voltage response means, Tr ₁ , Tr ₂ , RL ₁ and Tr ₃ , Tr ₄ , RL ₂ ... Window glass rising side, respectively. Transistors Tr ₁ to _{Tr 4} and relay RL ₁ which form the main parts of the self-holding circuit on the falling side,
RL ₂ , R ₂ , R ₃ , R ₄ , R ₅ , D ₂ , D ₃ ...Resistors R ₂ to R ₅ forming a reference voltage generation circuit as voltage generation means
and diode D ₂ and Zener diode D ₃ , R ₂₀ …
...Resistor that serves as resistance means for current detection.

Claims (1)

[Scope of Claims] 1. An on-vehicle DC power supply, a DC motor that drives an on-vehicle device and whose load current changes according to the load resistance of the on-vehicle device, a command means for instructing the drive of this DC motor, and a command for this command means. an electrical holding means for forming and holding a power supply path from the in-vehicle DC power supply to the DC motor; a detection means provided in the power supply path of the DC motor and outputting a detection signal according to the load current of the DC motor; a setting means for outputting a setting signal corresponding to a load current corresponding to a motor lock of the DC motor; comparing the detection signal and the setting signal; and when the detection signal exceeds the setting signal, the electrical holding is performed; a release means for canceling the holding action of the power supply path by the means to stop power supply to the DC motor; temperature compensation means for correcting either the detection signal or the setting signal according to the temperature compensation means; and a temperature compensation means for correcting either the detection signal or the setting signal according to 1. A load driving device for a vehicle, comprising voltage compensating means for correcting either the detection signal or the setting signal according to the voltage of the vehicle.