GB2199963A

GB2199963A - Control circuit for electrically operated windows

Info

Publication number: GB2199963A
Application number: GB8711645A
Authority: GB
Inventors: Gary Chris Fulks
Original assignee: Delco Chassis Overseas Corp
Current assignee: Delco Chassis Overseas Corp
Priority date: 1987-01-17
Filing date: 1987-05-18
Publication date: 1988-07-20
Anticipated expiration: 2007-05-18
Also published as: GB2199963B; GB8700970D0; GB8711645D0

Abstract

A control circuit for an electrically opeated vehicle window or sun roof includes a manually actuated switch 3,4 associated with each window or sunroof, relays 5 for setting the direction of rotation of the associated electric motors 2, a resistor 6 connected between the relays 5 and ground potential; and CPU 7. The CPU actuates the relays 5 and motors 2 in accordance with the switched command, and monitors the current through the resistor 6. From this it calculates and continuously updates a memory with data representing the current flow through the resistor 6 when the windows/sunroof are moving without meeting an obstruction and derives a peak valve for the current from this stored value 16 the current drawn exceeds the calculated peak value, the electric motor is stopped or reversed. The horn may also be sounded. A main sensor may cause closure of the windows/sunroof. <IMAGE>

Description

CONTROL CIRCUIT FOR ELECTRICALLY OPERATED WINDOWS This invention relates to a control circuit for an electric motor for an electrically operated window of, for example, a motor vehicle.

In particular, this invention relates to such a control circuit having a safety feature which stops or reverses the electric motor should an object (such as a childs hand) prevent full closure of the window.

Control circuits for electrically operated windows having this type of safety feature, and which use current sensing techniques for operation of the safety feature, are known.

Such known arrangements are disclosed, for example, in published GB patent application nos 2010957A, 2020928A and 2053513A, and in US patent no 3815005.

All of these known arrangements have the disadvantage that the point at which the safety feature is brought into effect (that is, when the force exerted by the window on the object) has to be set at a high level in order to prevent other parameters (such as the friction between the window and its side seals) accidentally triggering the safety feature. This high level of setting is also needed to allow for changes in these parameters during the life of the motor vehicle, and for changes in these parameters when a control circuit is manufactured for use on different motor vehicles.

It is an object of the present invention to provide a control circuit which overcomes the above disadvantages.

To this end, a control circuit in accordance with the present invention comprises a manually actuated switch; a relay for setting the direction of rotation of the electric motor; a resistor connected between the relay and ground potential; and computing means for actuating the relay and the electric motor in a accordance with the switched command, for monitoring the current through the resistor, calculating the rate of change of current through the resistor at predetermined time intervals, continuously updating and storing the rate of change data in a memory in the computing means for unobstructed opening and closing of the window, continuously updating and storing a peak current level trip based on the stored rate of change data, comparing the previously stored rate of change data with the presently calculated rate of change such that when the peak current level trip is exceeded, the computing means actuates the electric motor to stop or reverse the direction thereof.

The predetermined time interval is preferably 10 milliseconds. Preferably during the first 25 readings of current through the resistor the computing means actuates a self-testing routine, in order to avoid start-up errors.

With the arrangement of the present invention, the control circuit is self-calibrating in that the rate of change data stored in the computing means is continuously updated for unobstructed operation of the window. Consequently changes in parameters associated with movement of the window or initial installation can be compensated for, allowing the safety feature to be set at a lower (or higher) level than for previously known arrangements. For example, the safety feature can be set to be triggered in the present invention when the force exerted by the window on an object reaches 75N, as compared with the normally specified level of 100N in previously known arrangements. In the present invention, the force level is adjustable and controllable.

Preferably the control circuit includes a switch associated with the electric motor which sends a signal to the computing means when the window reaches the upper or lower limit of its travel, to prevent reversal of the electric motor, and, when the window is closing, to ensure an optimum force is applied by the window for sealing.

The control circuit of the present invention can be used to operate any number of electric motors and windows. In this case, the manually actuated switches are preferably mounted in a multiplexed switch bank comprising resistors connected in series and parallel. This arrangement has the advantages that the number of wires needed to connect the manually actuated switches can be reduced, and that it is a passive arrangement (resistors only) which causes no radio frequency interference. Further, the control circuit preferably comprises multiplexed power switching allowing a reduction in the number of connections to the electric motors, and in the number of relays, over previously known arrangements.

Further, in this case, only a single resistor is required for current monitoring for all the electric motors.

Preferably the control circuit is such that a single control stroke of less than a predetermined time of the manually actuated switch will fully open or close the window, unless the manually actuated switch is reactuated. If the control stroke is greater than the predetermined time (for example 0.25s), the window is actuated only whilst the manually actuated switch is actuated.

Where the motor vehicle has central door locking and a horn, preferably the computing means monitors the central door locking circuit, and on locking of the doors actuates the electric motor or motors to close the window or windows.

Alternatively the computing means may actuate the window or windows to leave a small gap, for example 2.5 cm. If the safety feature is actuated, the computing means preferably sounds the horn and then, after a suitable delay, attempts to close the obstructed window.

Preferably the control circuit includes a rain sensor which, on sensing rain, sends a signal to the computing means which then closes the window or windows. Preferably the rain sensor is a capacitive sensor.

This invention is further described, by way of example, with reference to the accompanying drawing in which the sole figure is a circuit diagram of a preferred embodiment of a control circuit in accordance with the present invention.

Referring to the drawing, the control circuit 1 is used to control the operation of five reversible electric motors 2, one each for the four side windows and the sunroof of a motor vehicle.

The control circuit 1 includes manually actuated switches 3,4 for actuation of the electric motors 2; relays 5 for setting the direction of rotation of the electric motors; a resistor 6 of 0.02 ohms; and computing means in the form of a microcomputer having a central processing unit 7. The control circuit 1 is powered by the vehicle battery which supplies a voltage B+.

The manually actuated switches 3 for the windows are mounted in a multiplexed switch bank 8 with resistors 9,10 which are interconnected as shown and also have the ratio of values as shown.

This arrangement requires only four output lines 11, as opposed to twelve on previously known arrangements.

The control circuit 1 also has multiplexed power switching in which the relays 5 are interconnected in such a way t.;dt only seven are required for reversible operation of the electric motors 2.

Switches 12 are mounted on the electric motors 2 and send signals to the central processing unit 7 via lines 13 when the windows are fully open or fully closed.

The central processing unit 7 has an input 14 from the ignition switch of the motor vehicle. The central processing unit 7 actuates the relays 5 via line 15 in accordance with the switched commands from the manually actuated switches 3,4, to actuate the electric motors 2.

The central processing unit 7 also monitors the current through the resistor 6 and calculates the rate of change of current through the resistor at predetermined time intervals of 10 milliseconds.

This rate of change data is stored and continuously updated in a memory in the central processing unit 7 for unobstructed opening and closing of each window and the sunroof. Based on the rate of change data, a peak current level trip is also stored and continuously updated. When the level of current which passes through the resistor 6 exceeds this peak current level trip due to an obstructed window, the safety feature is brought into effect, and the direction of movement of the obstructed window is reversed. The peak current level trip is set such that the obstructed window's direction is reversed when the force exerted thereby exceeds 75N.

The central processing unit 7 has a switched input 16 from a central door locking circuit of the motor vehicle. On locking the vehicle doors, the central processing unit 7 automatically closes the windows, unless a ventilation switch 17 is closed, in which case the windows are left slightly open. If a window is obstructed during this operation, the central processing unit 7 actuates the horn 18 of the motor vehicle. After a suitable delay, the central processing unit 7 then reattempts to close the obstructed window.

The control circuit 1 includes a capacitive rain sensor 19 which is connected via line 20 to the central processing unit 7. On sensing rain, the central processing unit fully closes the windows and sunroof, or moves the windows to a position in which they are left slightly open.

Claims

Claims:

1. A control circuit for an electric motor for an electrically operated window comprising a manually actuated switch associated with the window; a relay for setting the direction of rotation of the electric motor; a resistor connected between the relay and ground potential; and computing means for actuating the relay and the electric motor in accordance with the switched command, for monitoring the current through the resistor, calculating the rate of change of current through the resistor at predetermined time intervals, continuously updating and storing the rate of change data in a memory in the computing means for unobstructed opening and closing of the window, continuously updating and storing a peak current level trip based on the stored rate of change data, comparing the previously stored rate of change data with the presently calculated rate of change such that when the peak current level trip is exceeded, the computing means actuates the electric motor to stop or reverse the direction thereof.

2. A control circuit as claimed in Claim 1 wherein the predetermined time limit is 10 milliseconds.

3. A control circuit as claimed in Claim 1 or Claim 2 wherein the computing means actuates a self testing routine during the first 25 readings of current through the resistor.

4. A control circuit as claimed in any one of Claims 1 to 3 including a switch associated with the electric motor which sends a signal to the computing means when the window reaches the upper or lower limit of its travel.

5. A control circuit as claimed in any one of Claims 1 to 4 for a plurality of electric motors each associated with an electrically operable window, wherein the manually actuated switches are mounted in a multiplexed switch bank.

6. A control circuit as claimed in Claim 5 comprising multiplexed power switching and a single resistor for current monitoring for all the electric motors.

7. A control circuit as claimed in any one of Claims 1 to 6 wherein a single control stroke of less than a predetermined time interval of the or each manually actuated switch will fully open or close the associated window.

8. A control circuit as claimed in any one of Claims 1 to 7 for use in a motor vehicle having central door locking and a horn, wherein the computing means monitors the central door locking circuit and, on locking of the doors, actuates the or each electric motor to close the or each window.

9. A control circuit as claimed in Claim 8 wherein if the or each electric motor is actuated to close the or each window, and if the peak current level is exceeded, the computing means actuates the or each electric motor to stop or reverse the direction thereof, and sounds the horn.

10. A control circuit as claimed in any one of Claims 1 to 9 including a rain sensor which, on sensing rain, sends a signal to the computing means which then closes the or each window.

11. A control circuit as claimed in Claim 10 wherein the rain sensor is a capacitive sensor.

12. Control circuit substantially as hereinbefore described with reference to and as shown in the accompanying drawing.