Electricity: motive power systems – Limitation of motor load – current – torque or force
Reexamination Certificate
1994-12-13
2001-08-28
Wysocki, Jonathan (Department: 2837)
Electricity: motive power systems
Limitation of motor load, current, torque or force
Reexamination Certificate
active
06281648
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for controlling the drive of a power window. The device makes it possible to control a means both for maintaining the state of a switch operated for raising or lowering a door glass by a driving source such as a motor and for continuing the raising or lowering of the door glass.
2. Description of the Related Art
In a power window apparatus, a motor is usually used for raising and lowering a door glass. When a switch provided in a vehicle compartment (for example, on a door trim) is operated, the motor is driven until the door glass is completely closed or is completely opened.
The switch is designed for two-step operation. When a passenger releases the switch after holding the switch at a position for the first step, the switch is automatically turned off. When the passenger moves the switch to a position for the second step, an iron core having a coil produces magnetic force so that the switch is held in the second step by the magnetic force (magnet type switch). Accordingly, even after the passenger releases the switch, the door glass continues its upward or downward movement until the door glass is completely closed or is completely opened.
In a conventional power window apparatus, a motor current is detected using a resistor having a very small resistance (a shunt resistor) to stop the generation of magnetic force from the iron core (i.e., to shut off the current supplied to the coil) when the door glass is brought into a locked state, which occurs when the door glass is completely closed or is completely opened. As a result, the switch is returned to its off-position by an urging means.
When the switch cannot be returned by the urging means due to mechanical trouble, the supply of power to the motor is continued so that the motor abnormally heats up, which becomes a cause of breakdown. Accordingly, the conventional apparatus is provided with not only a mechanism for shutting off the supply of electricity by stopping the magnetic force but also a bimetallic switch interposed in a power supplying line connected to the motor. When heat is abnormally generated, the supply of electricity is shut off by the bimetallic switch.
However, since the mechanism for shutting off the electricity supplied to the motor must be independently provided for canceling the automatic operation and for preventing the motor from abnormally heating, the number of parts increases, resulting in decreased efficiency of assembly work. Also, since the bimetallic switch has poor reliability, periodic checks are needed, thereby decreasing the efficiency of maintenance work.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an improved apparatus for driving and controlling a power window in which the reliability of a mechanism for shutting off electricity supplied to a driving source such as a motor is increased.
Another object of the present invention is to provide an improved apparatus for driving and controlling a power window in which a mechanism for shutting off electricity can be formed by the same parts regardless of the causes of malfunctions.
Other objects of the present invention will become clear from the following description.
The present invention provides a device for control of driving a power window. The device includes continuation means adapted, once a switch is operated for raising or lowering a door glass by a driving force of a driving source, for automatically holding the operated state of the switch, so as to continuously raise or lower the door glass, and a thermistor disposed in the vicinity of the driving source and to be heated by a driving source locking current which flows through the thermistor upon complete closure or complete opening of the door glass, or to be heated by heat radiated from the driving source itself, so as to shut off electricity supplied to the driving source.
According to the present invention, the thermistor is inserted into the power supplying line. When a locking current of the driving source such as a motor locking current flows through the thermistor, the thermistor heats up and shuts off the current flowing therethrough so as to cancel the self-holding of the switch in the operated state. Accordingly, it is possible to shut off electricity supplied to the driving source with performance comparable to the conventional case in which a locking current is detected using a resistor having a very small resistance.
Also, the thermistor is disposed in the vicinity of the driving source. Hence, the thermistor can shut off the flow of current between both ends of the thermistor when the thermistor is heated by heat from the outside. In the case in which an on-state of the switch is maintained due to mechanical trouble even after the door glass is completely closed or is completely opened, the drive source itself heats up and radiates heat. Due to the radiation of heat, the thermistor is heated to shut off the flow of current between both ends thereof. Accordingly, the supply of electricity to the driving source can reliably be stopped even when any malfunction of the switch occurs.
As described above, since both of detection of ordinary locking current and detection of overheating of the motor can be effected using a single thermistor, the number of parts can be reduced and further the reliability of the apparatus can be increased.
In addition to the thermistor, a timer may be provided to compulsorily stop the supply of electricity after a predetermined period of time has elapsed.
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Iwata Hitoshi
Kinoshita Ken-ichi
Nishibe Yasushi
Cole Thomas W.
Kabushiki Kaisha Tokai-Rika-Denki-Seisakusho
Nixon & Peabody LLP
Wysocki Jonathan
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