Electricity: motive power systems – Limitation of motor load – current – torque or force
Reexamination Certificate
1999-09-24
2001-01-30
Martin, David (Department: 2837)
Electricity: motive power systems
Limitation of motor load, current, torque or force
C318S468000, C049S028000, C049S140000, C049S340000
Reexamination Certificate
active
06181094
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a power actuator for a motor-vehicle panel. More particularly this invention concerns such an actuator used to open and close the trunk lid, hatch back, or similar part of a motor vehicle.
BACKGROUND OF THE INVENTION
A standard power feature of a motor vehicle is a power opener/closer for the trunk lid, hatch back, or similar panel. The panel in question is normally mounted generally pivotally, typically by means of curved arms, for movement between a closed position sitting flush in its opening and an open position giving access to the opening. The mechanism can normally be actuated for opening by means of the vehicle's remote controller that also unlocks the passenger and driver doors. It is normally set to close when pushed down into a partially closed position. Thus the user can pop the trunk remotely, making it easy to load without having to put down whatever is going into the trunk to have hands free for operating the trunk latch, and easy to close in that the user need merely push it down somewhat, whereupon the power operator will take over and pull the panel to and latch it.
In a typical such system as described in U.S. Pat. No. 4,851,742 of Chapman the panel, here a trunk lid, is urged into the open position by a spring strong enough to raise the lid all the way up. A motor has a drive wheel or pulley around which is secured a cable whose outer end is attached to the door offset from the hinge so that when the cable is payed out the spring opens the panel and when the cable is wound up the door is pulled down against the force of the spring.
The problem with such a system is that it is fairly common for something, for instance the objects loaded into the trunk, to block full closing of the door. In this case the door will stop in a partially closed position. To prevent the motor from burning out, as the motor is normally shut off by automatic actuation of a switch as the panel reaches its fully closed position, a current-monitoring system is connected to the operator's controller. Thus, when the controller senses excess current consumption indicating that the motor is operating against too great a load, the motor is shut off and a warning signal is emitted.
This system is relatively complex. The motor has to be very powerful since it serves to operate against the spring on closing, although it only acts as a brake on opening. The opening movement is wholly the responsibility of the spring which must be very powerful. Finally the system is subject to damage if the panel is moved forcibly during an opening or closing cycle, if for instance a person tries to stop or raise the lid as it is closing.
Another system described in U.S. Pat. No. 2,850,140 of Compeau has a releasable coupling device which decouples the operator from the drive when closing of the door is impeded or some force operates opposite the closing force. While this system effectively protects the operator motor without the complexity of a current-monitoring system, once it decouples it leaves the power-closing feature inoperative. Recoupling the operator is a relatively complex job normally only undertaken by trained service personnel.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide an improved power operator for a motor-vehicle trunk lid or the like.
Another object is the provision of such an improved power operator for a motor-vehicle trunk lid or the like which overcomes the above-given disadvantages, that is which surely opens and closes the lid or panel in question, that is of simple construction, and that can be jammed or overridden with no damage to its parts and no requirement to reset it afterward.
SUMMARY OF THE INVENTION
A power operator for opening and closing a pivotal panel of a motor vehicle has according to the invention a spring engaged between the vehicle and the panel for urging the panel from a closed position into an open position, a rod having an outer end connected to the door and an inner end, and a clutch rotatable about a clutch axis and having an output member connected to the rod inner end and an input member. A drive motor connected to the input member is energizable for rotating the clutch elements and thereby displacing the rod and door. Another spring in the clutch rotationally decouples the clutch elements from each other only when a torque applied to the input element exceeds a predetermined limit. A controller energizes the motor for a predetermined amount of time.
This system has the advantage of extreme simplicity. If anything interferes with the opening or closing of the panel, e.g. a trunk lid or hatch back, the clutch will slip harmlessly, thereby preventing any of the operator parts from being damaged while protecting anything the panel is engaging from being damaged. There is no need to reset the system after something has happened that has caused the clutch to slip, merely to restart it in either direction. Similarly the slippage is even employed at the ends of the opening and closing strokes, eliminating the need for end-limit switches that start or stop these cycles. The system according to the invention even allows the panel to be opened manually in case of a power outage without damage to the operator. What is more, the operator completely opens the trunk, does not merely set it ajar, so that a person with his or her arms full can press the appropriate button on the remote to open the trunk fully so that the load can be set directly inside.
The output member carries offset from the axis a connection on which the rod inner end is pivoted. In addition the biasing means includes a spring biasing the clutch elements axially into engagement with each other. This spring includes at least one spring washer. The clutch elements are formed as clutch disks formed with axially projecting and interengaging teeth that have inclined flanks. More particularly the teeth of each disk are separated by intervening notches. The notches of one of the disks are angularly substantially longer than the teeth of the other of the disks. Thus there is some slip in the clutch at all times, whenever it changes direction, for smoothest possible action.
The drive includes a stepdown transmission having an input connected to the motor and an output gear fixed to one of the disks. Furthermore the clutch is provided with a housing containing the clutch elements and biasing means and formed with an arcuate slot centered on the clutch axis. The output member has a connection projecting axially through the slot.
REFERENCES:
patent: Re. 36267 (1999-08-01), Moore et al.
patent: 2850140 (1958-09-01), Compeau
patent: 4173845 (1979-11-01), Heesch
patent: 4851742 (1989-07-01), Chapman
patent: 4862640 (1989-09-01), Boyko et al.
patent: 5063760 (1991-11-01), Horita et al.
patent: 5069000 (1991-12-01), Zukerman
patent: 5189839 (1993-03-01), DeLand et al.
patent: 5239779 (1993-08-01), DeLand et al.
patent: 5319880 (1994-06-01), Kuhlman
patent: 5448856 (1995-09-01), Moore et al.
patent: 5531498 (1996-07-01), Kowall
patent: 5535553 (1996-07-01), Staser et al.
patent: 5636814 (1997-06-01), Rollert
Dubno Herbert
Kiekert AG
Martin David
Wilford Andrew
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