Window Driving Mechanism

The present invention relates to a mechanism for opening and closing a window. This is of particular benefit for windows in vehicles. Mechanisms for opening and closing windows are well known. They generally fall into two categories, manually operated and electrically operated types. The present invention relates to the electrically operated type. Electrically operated window opening and closing mechanisms are well known, but can experience a number of problems. One particular problem relates to the mechanism jamming during opening or closing of the window. This is a particular problem for larger windows which are more likely to shift their angular position relative to the sides of their frame during opening and closing. It is also a particular problem for windows which do not have parallel sides and/or are formed in a non-regular shape such that their mechanical opening mechanism is complex and therefore more likely to jam. Windows with single point regulators that cannot be located on the window's centre of gravity are also at increased risk of jamming. The problem of a jamming window is made worse for large and complex-shaped windows in that, in many circumstances, the manufacturing tolerances of the surrounds of such windows are not particularly high, leading to gaps and poor support which enable a window to move out of alignment very easily and therefore jam very easily.

The present invention seeks to overcome the problems associated with prior art automated window opening and closing mechanisms whilst still providing a mechanism which is of low cost and which is simple to install during a manufacturing process. It also seeks to provide a mechanism which is capable of providing complex opening and closing operations, such as predetermined opening to a particular position other than fully open or prevention of pinching of an obstruction during closing.

The present invention also seeks to provide designers of window systems with greater design flexibility to incorporate more complex shapes of windows and a more cost-effective, lighter weight and compact drive system than is currently available. According to the present invention there is provided a window driving mechanism, the mechanism comprising first and second driving motors, the first motor being arranged to drive, in use, a first side edge of the window, and the second motor being arranged, in use, to drive the other side edge of the window; and control means arranged to provide, in use, electrical synchronisation of the motors so that they can be driven to operate as if they were mechanically geared to one another. The present

invention has no limit to the type of electric motor used and is therefore open to a range of applications where different loads or size limitations require the use of a specific motor type. Such motor types include, but are not limited to: DC, AC, stepper, linear, and variants of these. The control means may use positional feedback for controlling first and second said motors, which may be arranged to provide a proportional, integral and differential (PID) control signal to the first motor and a phase-locked loop (PLL) control component to the second motor, the input of the phased locked loop component being a function of the position of the window edge being driven by the first motor. The positional feedback and control means enables the motors to track one another and keep the window balanced and in an optimum trajectory during opening and closing. This addresses the imbalances that could arise in a single point regulator system where the load on one side of the window could be greater than that on the other, due to friction or an offset centre of gravity. Positional feedback also allows for a more sophisticated trap detection system to be employed since the absolute position and velocity of the window is known at all times. If there is a sudden drop in velocity whilst closing and the window is not within a specified distance of its closed position, a trap can be assumed and appropriate action taken. Positional feedback also allows detection of when the window reaches its open and closed physical stops thus allowing the control means to stop driving the motors shortly after to avoid overheating and damage.

The control means may be further arranged to perform a realignment of the window through appropriate control of the driving of the motors. In such a circumstance the realignment may be performed by first driving one of the motors whilst stopping movement of the other motor until the window rotates to a first extreme position where it can move no further, following by driving of the said one motor in the opposite direction to rotate the window in an opposite direction to another extreme position in which it will move no further, the control means further comprising means for detecting a mid-point between the two extreme positions and driving the motors to position the window and the mid point before further driving of the window. The points at which the window can move no further can be detected by monitoring motor current which increases noticeably when the motor stalls, or by positional feedback which shows a decrease in velocity down to zero. By monitoring motor current during normal operation and a complete jam (motor stall), a suitable threshold can be set for trap detection. With the invention the threshold can be set for each individual installation

by running the window through a series of operating cycles and induced trap conditions such that the controller "learns" the particular characteristics of a specific installation. Thus, in the event of an actual trap condition, the load on the window increases rapidly resulting in a rise in motor current which, when exceeding the set threshold, enables the appropriate action to be taken by the controller.

The mechanism of the present invention may further comprise additional sensors for detecting the extreme open and closed positions of the window and may have a control means arranged to receive such inputs. The control means may further be arranged to receive inputs from motor load sensors or other sensors detecting the location of an unwanted object in the closing path of the window to provide additional driving signals based thereon to the motors.

The mechanism of the present invention may have a number of preset programmable positions so that an end user may install it such that it has a specific operation, such as slightly open for venting, child-safe half open position, auto down, auto up, etc.

A further advantage of the present invention is that it employs two motors rather than one. This means that each motor can be smaller and therefore, in many circumstances, it is easier to install the arrangement of the present invention as more positions are available within a door or its installation. One example of the present invention will now be described with reference to the accompanying drawings, in which:

Figure 1 is a schematic diagram of an example mechanism according to the present invention;

Figure 2 is a schematic diagram of the control components of the system of figure 1 ;

Figure 3 is a schematic block diagram of the control components of the present invention shown in figures 1 and 2;

Figure 4 is a schematic diagram showing a misalignment correction procedure performed by the invention of figures 1 to 3; Figure 5 is a diagram showing the operation of the invention of figures 1 to 3 on a window of non-uniform shape; and

Figure 6 is a schematic block diagram of the control components of the invention of figure 1 for complex window movements.

Referring to Figure 1 , the window mechanism of the present invention has first and second drive mechanisms 1 ,2 which engage with either edge of a window 3 to

drive it between a position in which it is fully down and a position in which it is fully up.

In Figure 1 , the fully up position is detected by one or more sensors 6 and the fully down position is detected by one or more sensors 5, respectively. The sensor may be a photo-sensor, resolver, potentionmeter, Hall effect, or back EMF, for example, but it will be appreciated, however, that alternative arrangements may be used for position detectors, such as a position encoder arrangement as described below.

Each of the drive mechanisms 1 , 2 comprises an independently controllable motor 7, 8 and associated linkage mechanism 9, 10. The specific arrangement of the motor 7, 8 and linkage mechanisms 9, 10, and the manner in which they contact with the window 3, will be dependent upon the particular application, and will be one of many alternatives, some of which might be well known to a person skilled in the art.

In this example, the linkage mechanisms engage the side edges of the window though may, in other examples, engage the window at positions adjacent to these edges so as to be able to drive them.

Figure 2 shows some of the key components of the drive mechanism. A microcontroller 20 receives input from control key "up" and "down" switches 21 , 22. Based on these inputs and direction signals from fully open and fully closed position switches 6,5, drive outputs are provided to the motors 7,8 via drive circuitry (such as an H- bridge) 23, 24. Encoders 25, 26 associated with each motor 7,8 provide feedback to a micro-controller 20. It is not essential for the micro-controller 20 to be used to provide the appropriate control mechanism, but as will be discussed below, this does provide benefits in terms of providing additional operations by simple appropriate programming of the micro-controller 20. In addition, whilst it is not essential to provide fully closed and fully open detection in the form of the sensors 5, 6, doing so provides benefits in terms of giving the micro-controller the ability, in conjunction with the feedback from the encoders 25, 26, to know the exact position of the window at all times.

Upon input from the "up" and "down" switches 21 , 22, the micro-controller 20 determines the location for the window 3 and works out a position and velocity profile for its movement. Such a profile involves acceleration of the window 3 from its starting position to a set velocity, and deceleration when the user input has gone away or where the window 3 is nearing either of its up or down limits. Based on this, an appropriate input is provided to a control loop, the key components of which, together with its structure, is shown in Figure 3. In Figure 3 it is shown that a required position

30 is fed to a proportional, integral and differential (PID) control component 31 and on via a pulse width modulated (PWM) drive 32 to the first of the two drive circuitry components 23 and its associated motor 7. In this example an additional gear box 33 is shown which feeds the output of the motors to the engaging mechanism (not shown) associated with one side of the window 3. Feedback from the encoder 25 is passed back to the PID control component 31 and is also fed to a phase-locked loop (PLL) configuration, the output from the PLL component 34 being fed to a second PWM drive 35 and the second of the two drive circuitry components 24 to the second motor 8. Again, in this example, a further gear box 36 is shown associated with the drive mechanism (not shown) at the right hand side of the window 3. The second encoder 26 passes an output back to the PLL component 34. It will be appreciated that the control mechanism could be arranged so that the PLL component 34 acts on either the left or right hand drive mechanism with the PID control component 31 acting on the other drive mechanism, respectively. The operation of this control mechanism provides a simple and effective gearing between the left and right hand sides of the drives for the window 3. This means that the two motors 7, 8 are effectively geared to operate together in use, even though there is no mechanical connection. By providing electric gearing, as opposed to a mechanical mechanism, the two motors 7, 8 can be driven to provide balanced raising and lowering of the window 3 without introducing a high level of complexity into the drive mechanism which would increase its cost, reduce its reliability, and also make it far more difficulty to install.

Another possible arrangement is to use two independent PID control loops as shown in Figure 6. This provides independent control of each motor drive and allows for more complex electronic gearing and window movements. The gearing relationship between the two motor drives is determined by the position translation block 38. The required window position is fed into 38 which translates this into appropriate signals to drive the two PID loops. The translations can be based on either formulae or lookup tables and will take into account variable parameters associated with calibration.

Benefits of the present invention are set out below with reference to Figures 4 and 5.

As discussed above, if the window 3 is large, not centred, imbalanced and/or if the retaining mechanism (not shown) for the window 3 does not have strict manufacturing tolerances, it is possible for the window 3 to move out of alignment so that its side edges do not pass up or down in a direction which is actually parallel to the mechanisms 1 , 2. This can lead to jamming if the misalignment becomes so great

that the window 3 engages with components to one or the other sides of it, such that it cannot move either upwards or downwards. The types of positions where this occurs are shown in steps B and C of Figure 4. Alternatively, as shown in Figure 5, such jamming can occur with a window of non-uniform shape simply because of its position within a retaining mechanism and the complexity of its shape and the relative movement of the window within the retaining mechanism.

Figure 4 (step A) shows a situation where the window 3 has jammed by slight misalignment and engagement with a supporting edge 40 of the frame surrounding the window 3. Such a situation was most likely to occur during upward motion of the window 3, but regardless or whether or the not the window 3 is moving upward or downward a jam occurs and is detected by the micro-controller 20 through monitoring of the load on the motors 7, 8 and/or the output of the encoders 25, 26. The microcontroller 20 is then arranged to control the motors 7, 8 to firstly drive, in this example, the second motor 8 to urge the window 3 upward whilst stopping the first motor 7. This leads to the position shown in Figure 4 (step B), where the window 3 is rotated anticlockwise as far as it can be moved. The micro-controller 20 then drives the second motor 8 in the opposite direction whilst maintaining the first motor 7 in a stopped mode such that the window moves clockwise until it reaches a further extreme position shown in Figure 4 (step C). The extreme positions can be detected by, again, monitoring the load on the second motor 8, and/or encoder 26 output. The exact positions when the two extremes are reached are detected by use of the outputs of the encoders 25, 26. Following this information the micro-controller 20 can determine a mid-point between the two extremes and drive the second motor 8 to move the window 3 to that mid point. Alignment is then determined, as shown in Figure 4 (step D) and the first motor 7 can then be driven, geared with the second motor 8, as re-alignment has been performed. This arrangement has particular advantages in that it provides a self-alignment procedure that can be performed when the window is first installed, without complex measurement or manipulation by an installing operator. It also ensures that, even though the life time of the use of the window, variations in the shape of the frame can be compensated for.

Figure 5 shows a similar-alignment that can occur if a window of irregular shape is being moved by the system of the present invention. Although the misalignment of the window 3 may occur for different reasons, the micro-controller 20 can, similar to the process described in Figure 4, operate to self-align the system to remove the jam. With an irregular window of the type shown in Figure 5 it is possible to structure the

control processes performed by the microprocessor 20 such that the relative gearing of the motors 7,8 can vary during the upward and downward motion of the window 3 to compensate for its unusual shape and its relative position with respect to the frame work which retains it. This can be achieved simply without the need to provide complex mechanical arrangements to adjust alignment during the motion of the window to compensate for its irregular shape. Figure 5 (step A) shows a window alignment before calibration, wherein the window is slightly skewed. Figure 5 (step B) shows first calibration step, which is to drive the right-side of the window down until the encoder increments stops. Figure 5 (step C) shows the second calibration step wherein if the encoder count from optimum window position to jam condition is known by design, the right side of the window can be driven up by this known count to put the window in its optimum position.

Figure 6 shows a system for complex window movements. In this configuration the required window position is translated into separate left and right drive positions, which can be complex for more demanding applications, for example, when the left and right sides may be required to follow different profiles as the window opens and closes. The required position 30 is fed to a motor drive position translation component 38 which then feeds the individual control signal, for each side of the window, into a pair of proportional, integral and differential (PID) controllers 31 , 37 and on via pulse width modulated (PWM) drives 32, 35 to the respective drive circuitry components 23, 24 and its associated motor 7, 8. In this example, additional gearboxes 33, 36 are shown which feed the output of the motors to the engaging mechanism (not shown) associated with the respective sides of the window 3.

With any of the arrangements of the present invention the control operations can be adjusted by simple re-programming of the micro-controller 20. This means that additional features in the mechanism can be included simply and effectively. Examples of additional procedures include something such as simple "shaking" motion to attempt to release the window 3 if it has become jammed in the closed position (perhaps through ice freezing it shut). Other possibilities include the ability of the micro- controller 2 to incorporate input from further sensors, or monitor motor loads to detect an object becoming trapped in the window during closing and prevent further movement of the window to avoid potential injury to a passenger or damage to an object being trapped. It will be appreciated that other control mechanisms can be used for motor control . For example, the semiconductor manufacturer Microchip has numerous application notes in this field relating to the use of its micro controllers. The

key aspects of motor control are the parameters of the motor that are to be controlled based on the inputs to the control system. Such parameters include: position, speed, direction and/or torque. The control means relies upon feedback from the motor or associated sensors to control these parameters. Such feedback may include: motor back MEF, motor current, rotary encoder, and/or torque sensor.