Open roof assembly and method for operating the same

Abstract

An open roof assembly in a roof of a vehicle, comprising a movable arrangement of closure members for selectively covering or at least partially exposing an opening in the roof, an electric motor operatively coupled to the closure members by a mechanical drive assembly for moving the closure members, an electric drive unit for providing a supply signal to the electric motor, and a control unit operatively coupled to the electric drive unit for controlling operation of the electric motor. The electric drive unit comprises four switching devices in a bridge configuration and the control unit is configured to control movement of the closure members by controlling operation of the switching devices, and to cause a safety stop by immediately reversing the polarity of the supply signal during movement of the closure members.

Description

TECHNICAL FIELD

[0001] The present invention relates to an open roof assembly in a roof of a vehicle. BACKGROUND

[0002] It is known to provide an open roof assembly in a roof of a vehicle. In particular, in known open roof assemblies a movably arranged closure member is provided for selectively covering an opening in the roof or at least partially exposing this opening. An electric motor can be provided and is operatively coupled to the closure member by a mechanical drive assembly for moving the closure member between a closed position in which the opening is covered and an open position in which the opening is at least partially exposed. Further, an electrical drive unit for providing a supply signal to the electric motor and a control unit operatively coupled to the electrical drive unit for controlling the operation of the electric motor, and thus the position and movement of the closure member can be provided.

[0003] Under normal operating conditions, the control unit is configured to control the electric motor and thus the closure member. The control unit is configured to switch the electric motor on or off depending on, for example, a user command. The electric motor is operatively coupled to the closure member by a mechanical drive assembly such that when the electric motor is switched on, the closure member moves.

[0004] However, the mechanical drive assembly typically has a certain play, due to which the movement of the closure member can slightly lag behind the operation of the electric motor. Under normal operating conditions, this lag is not a problem. Under abnormal conditions, in particular when an object can be pinched between the moving closure member and the edge of the opening, the play in the mechanical drive assembly causes the closure member to further move due to, for example, inertia even when the electric motor has been switched off and has stopped. This overshoot can result in an increased force exerted by the closure member on the object. It is of course desirable to reduce this force. SUMMARY

[0005] It is an object of the present invention to provide a reliable, simple and cost-effective open roof assembly with reduced overshoot in case of a safe stop and a corresponding method of operation.

[0006] In a first aspect, the object is achieved in an open roof assembly in a roof of a vehicle according to the present application. The open roof assembly comprises a moveable arranged closing member for selectively covering or at least partially exposing an opening in the roof, an electric motor operatively coupled to the closing member by a mechanical drive assembly for moving the closing member, an electric drive unit for providing a supply signal to the electric motor and a control unit operatively coupled to the electric drive unit for controlling operation of the electric motor, wherein the electric drive unit comprises four switching devices in a bridge configuration and wherein the control unit is configured to control movement of the closing member by controlling operation of the switching devices and, during movement of the closing member, to cause a safe stop by immediately inverting a polarity of the supply signal.

[0007] The use of at least four switching devices in a bridge configuration in the electric drive unit provides more electric drive modes compared to two switching devices that typically only provide two electric drive modes, i.e. forward and reverse. To stop the electric motor, both switching devices are closed, which enables the electric motor to rotate with movement of the closing member due to inertia. The bridge configuration of the four switching devices further provides a brake mode in which the supply terminals of the electric motor are short-circuited. As is known in the art, a short-circuit on the supply terminals effectively brakes the rotation of the electric motor. Such active braking is known to be used for safe stopping. However, the active brake mode does not solve the overshoot problem due to play in the mechanical drive assembly. Therefore, in the open roof assembly according to the present application, the electric drive assembly is controlled by the control unit such that, for safe stopping, the electric motor is immediately switched to the opposite direction.

[0008] While the above described prior art safe stopping allows the closing member to gradually reduce speed based on mechanical resistance in the electric motor and the mechanical drive assembly, thereby absorbing play in the mechanical drive assembly, the safe stopping according to the present application absorbs the play by reversal of the electric motor. Therefore, overshoot of the closing member is effectively reduced.

[0009] In one embodiment, the reversal of polarity is maintained for at least a first reversal time period, wherein the first reversal time period is selected based on an amount of backlash in the mechanical drive assembly, such that in the first reversal time period, the backlash in the mechanical drive assembly is at least partially absorbed by the reversal of the electric motor, and the movement of the closure member is stopped. In the first reversal time period, the closure member is stopped as quickly and efficiently as possible for the purpose of reducing a safety stop overshoot, i.e. an amount of travel after the trigger of a safety stop is needed. For example, the first reversal time period can be configured as the time period needed for the closure member to reach a speed equal to zero in the original direction of movement, i.e. in the direction in which the closure member was moving at the time of the trigger for a safety stop. Due to the inertia of the electric motor and other components, the closure member can subsequently even move in the opposite direction after the electric motor has been turned off.

[0010] In another embodiment, the control unit can be configured to continue with a second reversal time period after the first reversal time period. In such an embodiment, the movement of the closure member is stopped during the first reversal time period, and during the second reversal time period, the closure member is controlled to move in the opposite direction, e.g. to release a pressed or jammed object. Only in the second reversal time period, the closure member actually moves in the opposite direction, whereas in the first reversal time period, the speed of the closure member is reduced and eventually stopped. It is noted that, as used herein, the opposite direction refers to the direction opposite to the direction of movement of the closure member prior to the safety stop.

[0011] The second reversal time period can be suitably selected by the person skilled in the art. For example, the second reversal time period can be relatively short to only move the closure member a small distance to release a jammed object. In another example, the second reversal time period can be selected such that the closure member is moved to a predetermined position, e.g. a fully open position or a specific partially open position. The present application is not limited to any particular duration or selection of the second reversal time period.

[0012] In one embodiment, the switching device is a solid state switching device, in particular a transistor, and more particularly a MOSFET transistor. The bridging electric drive assembly can comprise a relay, but preferably, the switching device is a solid state device with a short switching time, thereby further reducing a safety stop overshoot.

[0013] Furthermore, in a particular embodiment, the control unit is configured to control the movement of the closure member by applying a pulse width modulation (PWM) control method. For example, using a solid state switching device, such as a FET transistor, the control unit can perform a pulse width modulation control, which is known per se in the art, enabling to adjust the speed of the electric motor. Using such PWM control and adjusting the speed of the electric motor, the control unit can be configured to determine the actual position of the closure member and to apply a closed loop control method using the determined actual position of the closure member. In closed loop control, the speed of the electric motor can be adjusted and controlled based on the determined actual position. For example, the determined actual position can be compared to a desired position and the supply signal to the electric motor can be adapted in response to any deviation between the desired position and the actual position. Furthermore, for a predetermined stop, the speed of the electric motor can even be reduced before reaching the desired position, enabling to position the closure member exactly at the desired position. Such closed loop control is known per se from the prior art and is believed to be obvious to the person skilled in the art. Therefore, the closed loop control method is not further elucidated herein.

[0014] In one embodiment, the control unit is configured to cause a predetermined stop of the movement of the closure member by short-circuiting the electric motor. As used herein, a predetermined stop refers to an intended stop position known beforehand by the control unit during the movement of the closure member. Therefore, the control unit can be configured to take into account an overshoot and to stop the electric motor in time such that the closure member reaches the intended position after the overshoot, wherein a certain amount of inaccuracy in the positioning can be considered acceptable. Therefore, the control unit can be configured to apply a different stopping procedure when stopping at a predetermined intended position than when stopping at an unexpected position and at an unexpected time for safety reasons.

[0015] It is noted that such control unit configured for different stopping procedures depending on the type of stop required can also be used appropriately and advantageously with other types of electrically driven assemblies and is not specifically limited to the open roof assembly according to the present application. For example, in the present application, the reversal of the electric motor for absorbing play in the mechanical drive assembly prevents a gradual deceleration of the closure member. Therefore, a relatively hard stop is performed. Therefore, the inertia of the closure member will be absorbed by the mechanical drive assembly, such as the drive cable and / or the gears. Depending on a number of parameters, the resulting high force can be too high such that a part of the mechanical drive assembly is damaged. For example, the drive cable can be stretched. Therefore, such stopping method can not be preferred unless required for safety reasons. In such a case, another stopping method can be applied in case of an intended stop.

[0016] In one embodiment, the control unit is configured to detect an obstacle in the travel path of the closure member in motion and to cause the safety stop upon detection of such obstacle. While a separate sensor system can be provided to detect obstacles, e.g. by object, the control unit can be configured to detect such obstacles. For example, based on input from a common Hall sensor operably coupled to the electric motor and the current consumed by the electric motor, the control unit can be configured to detect changing conditions and determine that a foreign object has been crushed. Further, based on similar considerations and possibly one or more additional mathematical models, the control unit can be configured to derive the position of the closure member without a specific or dedicated position sensor. Thus, in the above embodiment with closed loop control, the control unit can be configured to derive the actual position without applying a dedicated sensor.

[0017] In one aspect, the present application further provides a method of operating an open roof assembly. The open roof assembly comprises a movable arrangement of closure members for selectively covering or at least partially exposing an opening in the roof, an electric motor operably coupled to the closure members by a mechanical drive assembly for moving the closure members, an electric drive unit for providing a supply signal to the electric motor, and a control unit operably coupled to the electric drive unit for controlling operation of the electric motor. The electric drive unit comprises four switching devices in a bridge configuration. The method comprises the control unit performing the steps of controlling movement of the closure members by controlling operation of the switching devices, and causing a safety stop by immediately reversing a polarity of the supply signal during movement of the closure members.

[0018] In one embodiment of the method, the step of reversing the polarity is maintained for at least a first reversal time period, wherein the first reversal time period is selected based on an amount of play in the mechanical drive assembly, such that in the first reversal time period the play in the mechanical drive assembly is at least partially absorbed by the reversal of the electric motor, and the movement of the closure members is stopped.

[0019] In another aspect, the present application provides a computer software product comprising computer readable and executable instructions for instructing a computer processor to perform the method steps according to the present application. In particular, such a computer processor can be comprised in a control unit of an open roof assembly. BRIEF DESCRIPTION OF DRAWINGS

[0020] Further areas of applicability of the present application will become apparent from the detailed description given below. However, it should be understood that the detailed description and specific examples, while indicating embodiments of the application, are given by way of illustration only, since various changes and modifications within the scope of the application will become apparent to those skilled in the art from this detailed description, which follows, taken in conjunction with the accompanying drawings in which:

[0021] FIG. 1A perspective view of a roof with an open roof assembly;

[0022] FIG. 1B perspective view of an open roof assembly FIG. 1A

[0023] FIG. 2 top view of an embodiment of an open roof assembly with a movable closing member and a corresponding drive assembly; and

[0024] FIG. 3A diagram showing an electric drive unit as used in the present application;

[0025] FIG. 3B diagram showing an embodiment of a control unit applying a closed loop control method;

[0026] FIG. 4A diagram showing overshoot of a closing member;

[0027] FIG. 4B diagram showing motor speed and closing member speed according to prior art embodiments;

[0028] FIG. 4C diagram showing motor speed and closing member speed according to embodiments according to the present application;

[0029] FIG. 5 diagram showing control signals according to a comparative example of the prior art;

[0030] FIG. 6A diagram showing a first embodiment of a method according to the present application; and

[0031] FIG. 6B diagram showing a second embodiment of a method according to the present application. DETAILED DESCRIPTION

[0032] The present application will now be described with reference to the drawings, wherein like reference numerals have been used to identify like elements throughout the several views.

[0033] FIG. 1A ​A roof 1 with an open roof assembly disposed therein is shown. The open roof assembly includes a movable panel 2a and a fixed panel 2b. The movable panel 2a is also referred to as a closing member because it is movable above a first roof opening 3a, thereby enabling the first roof opening 3a to be opened and closed. A vent 4 is disposed at the front side of the first roof opening 3a.

[0034] In the illustrated embodiment, the movable panel 2a can be in a closed position, which is the position in which the movable panel 2a is arranged above and closes the first roof opening 3a, and is therefore generally arranged in the plane of the roof 1. Furthermore, the movable panel 2a can be in an inclined position, which is the position in which the rear end RE of the movable panel 2a is raised while the front end FE of the movable panel 2a remains in the closed position compared to the closed position. Additionally, the movable panel 2a can be in an open position, which is the position in which the movable panel 2a slides open and the first roof opening 3a is partially or completely exposed.

[0035] It should be noted that the roof 1 shown corresponds to a passenger vehicle. However, the invention is not limited to passenger vehicles. It is also conceivable that any other type of vehicle may be equipped with a movable panel.

[0036] FIG. 1B Showing with FIG. 1A The roof shown has the same panels 2a and 2b. Specifically, although FIG. 1A The open roof assembly is shown in the open position, but FIG. 1B This is an exploded view of the open roof assembly in the closed position. Furthermore, in FIG. 1B The exploded view shows the presence of a second roof opening 3b. The first roof opening 3a and the second roof opening 3b are disposed within the frame 5 of the open roof assembly. The edge 5a of the frame 5 defines the first roof opening 3a.

[0037] The second roof opening 3b is arranged below the fixed panel 2b, allowing light to enter the vehicle interior space through the fixed panel 2b, which is assumed to be a glass panel or a similarly transparent panel, for example, made of plastic or any other suitable material. The second roof opening 3b with a transparent or translucent fixed panel 2b is optional and may be omitted in another embodiment of the open roof assembly.

[0038] The air guide plate 4 is typically made of a flexible material, such as a woven or nonwoven fabric, web, or mesh with through-holes arranged therein. The flexible material is supported by a support structure 4a (e.g., a rod-like or tubular structure), which is directly or indirectly hinged to the frame 5 at a hinge joint 4b.

[0039] The deflector 4 is arranged in front of the first roof opening 3a and regulates the air flow when the movable panel 2a is in the open position. In its raised position, the deflector 4 reduces the inconvenient noise due to the air flow during driving. When the movable panel 2a is in the closed position or in the tilted position, the deflector 4 is pressed underneath the front end FE of the movable panel 2a.

[0040] Generally, when the movable panel 2a is slid to the open position, the deflector 4 is raised by spring force, and when the movable panel 2a is slid back to its closed position, the deflector 4 is pushed down by the movable panel 2a. In FIG. 1A In Fig. 2, the movable panel 2a is shown in the open position, and the deflector 4 is shown in the raised position. In FIG. 1B In Fig. 3, the movable panel 2a is shown in the closed position, and the deflector 4 is accordingly shown in its pressed-down position.

[0041] FIG. 1B Further shown is a drive assembly with a first guide assembly 6a, a second guide assembly 6b, a first drive cable 7, and a second drive cable 8. The first guide assembly 6a and the second guide assembly 6b are arranged on respective side ends SE of the movable panel 2a and can each comprise a guide and a mechanism. The guide is coupled to the frame 5, while the mechanism comprises a movable part and is slidable in the guide. The first drive cable 7 and the second drive cable 8 are provided between the mechanism of the respective guide assembly 6a, 6b and the electric motor 9.

[0042] The drive cables 7, 8 couple the electric motor 9 to the mechanism of the respective guide assembly 6a, 6b such that upon operating the electric motor 9, the mechanism starts to move. In particular, the core of the drive cables 7, 8 is moved by the electric motor 9, thereby pushing or pulling the mechanism of the respective guide 6a, 6b. Such a drive assembly is well-known in the art and is therefore not further elucidated herein. Further, any other suitable drive assembly can also be employed without departing from the scope of the present invention. Moreover, in a particular embodiment, the electric motor can be operably arranged between the respective guide and the respective mechanism of the guide assembly 6a, 6b, and in such an embodiment, the drive assembly can be completely omitted.

[0043] In the illustrated embodiment, the guide assemblies 6a, 6b can start moving as the rear end RE of the movable panel 2a is raised, thereby bringing the movable panel 2a into the tilted position. Then, the guide assemblies 6a, 6b can start sliding to bring the movable panel 2a from the tilted position into the open position. However, the present application is not limited to such an embodiment. For example, in another embodiment, the movable panel 2a can not be movable to the tilted position by raising the rear end RE, but by first lowering the rear end RE and then sliding the movable panel 2a under the fixed panel 2b or any other structure or element provided behind the rear end RE of the movable panel 2a to reach the open position. In a further exemplary embodiment, the movable panel 2a can be movable only between the closed position and the tilted position or only between the closed position and the open position.

[0044] In the illustrated embodiment, the electric motor 9 is mounted near or under the front end FE of the movable panel 2a at the recess 10. In another embodiment, the electric motor 9 can be positioned at any other suitable position or location. For example, the electric motor 9 can be arranged near or under the rear end RE of the movable panel 2a or under the fixed panel 2b.

[0045] The control unit 11 is schematically shown and operably coupled to the electric motor 9. The control unit 11 can be any type of processing unit, i.e. a software-controlled processing unit or a dedicated processing unit, like an ASIC, as is well known to the skilled person. The control unit 11 can be a stand-alone control unit, or it can be operably connected to another control unit, like a multi-purpose, general vehicle control unit. In yet another embodiment, the control unit 11 can be embedded in or part of such a general vehicle control unit. Basically, the control unit 11 can be embodied by any control unit suitable, capable and configured for performing the operation of the electric motor 9 and thus of the movable roof assembly.

[0046] FIG. 2 An open roof assembly with a mechanical drive assembly is schematically shown. The open roof assembly comprises a movable closure member 2a for closing a first roof opening 3a, a fixed panel 2b and a support frame 12. The support frame 12 is arranged and configured to mount and support the open roof assembly on a body frame of a vehicle. In FIG. 2 The movable closure member 2a is schematically coupled to the drive cable 16 by a coupling element 14. In practice and as FIG. 1A and FIG. 1BAs shown, the movable closing member 2a is arranged on the support frame 12 by means of guide assemblies 6a, 6b, and each guide assembly 6a, 6b is operated by means of an associated drive cable 16. In the shown embodiment, the drive cable 16 can be moved by means of an electric motor through an effective mechanical coupling with a suitable gear 18. The drive cable 16 and the gear 18 are comprised in a mechanical drive assembly which is operatively coupled to the electric motor 9 and to the closing member 2a.

[0047] The gear 18 is mechanically coupled to the electric motor 9 which is operatively coupled to a control unit 11. The control unit 11 can comprise an electronic control circuit, possibly including a computer processor. Moreover, the control unit 11 can be operatively coupled to one or more sensors. For example, Hall sensors and typically two Hall sensors are arranged in the vicinity of the electric motor 9 so that an alternating signal from the Hall sensors is received by the control unit 11, based on which the control unit 11 is able to derive the speed of the electric motor and the amount of displacement of the closing member. Other sensors can also be provided and coupled to the control unit 11.

[0048] In particular when closing the closing member 2a, also when opening, objects can be squeezed and become stuck between the front edge of the closing member 2a and the support frame 12. In order to prevent damage to the objects and to the convertible roof assembly, the convertible roof assembly can be provided with means for detecting such squeezing and possible sticking, wherein such means can comprise dedicated sensors and model-based methods, for example embedded in software. Such methods and means are known in the art and are not further elucidated herein, with the remark that the present invention is not limited to any particular method or means for such squeezing and sticking detection. According to the present invention, upon detection of squeezing or entrainment, a safety stop is caused, which can deviate from the normal stop.

[0049] FIG. 3A A bridge configuration of four switching devices S1, S2, S3 and S4 comprised in the electric drive unit 20 is shown. A voltage source 22 is coupled to the supply terminals of the electric drive unit 20, and an electric motor M is coupled to the output terminals of the electric drive unit 20. The four switching devices S1-S4 are operatively coupled to the control unit 11 so that the control unit 11 is able to switch the switching devices S1-S4 between an on (conducting) state and an off (non-conducting) state.

[0050] It is known that the switching devices S1-S4 can be any type of switching device, but in a practical embodiment the switching devices S1-S4 are MOSFET transistors with parallel intrinsic diodes. Such embodiments are well known and are not further elucidated herein.

[0051] Furthermore, as is known in the art, the electric motor M can be driven in multiple modes by appropriately controlling the four switching devices S1-S4. In forward mode, only switching devices S1 and S4 are in the conducting state, and current flows through the electric motor M, driving it in the forward direction. In backward mode, only switching devices S2 and S3 are switched on, allowing current to flow through the electric motor M in the opposite direction, driving it in the backward direction. In active braking mode, only switching devices S1 and S2 are turned on, or only switching devices S3 and S4 are turned on, thus short-circuiting the electric motor M, effectively braking it.

[0052] Furthermore, regenerative braking mode is known. When the electric motor M operates in forward or backward mode and all switches are switched to non-conducting mode, the operating electric motor M moves due to inertia and begins to act as a generator, thereby generating current to charge voltage source 20. It should be noted that current can then be forced through intrinsic diodes, causing the transistors to dissipate a relatively large amount of energy and generate a significant amount of heat. To prevent overheating, the switches can be switched so that the electric motor switches from the forward direction to the backward direction, for example, switching the transistors carrying the generated conductive current, thereby reducing energy dissipation in these transistors and thus generating less heat in the transistors.

[0053] As described above, regenerative braking is known for stopping the electric motor M while charging the voltage source 20. In this invention, regenerative braking is used to stop the closing member 2a. Due to the backlash in the mechanical drive assembly, the closing member 2a can still move due to inertia when the electric motor M stops. Therefore, maintaining the regenerative braking mode preferably until the closing member 2a stops effectively means that the electric motor M stops and reverses, thereby absorbing at least a portion of the backlash in the mechanical drive assembly, thus reducing the overshoot of the closing member 2a. This is in FIG. 4A to FIG. 4C More details are shown and about FIG. 4A to FIG. 4C Describe it.

[0054] FIG. 3B It shows that it can be used with FIG. 3A A simplified diagram of a closed-loop control system used in conjunction with an electric drive unit 20. In the illustrated closed-loop control system, a set position 30 is provided as a starting point. A proportional controller 32 (e.g., a PID controller) uses the deviation between the actual position and the set position as input and determines the setting for the electric motor. The setting for the electric motor is output to a motor control unit 34, which drives switching devices S1-S4 (… FIG. 3A) to drive the electric motor. By high frequency switching at least one of the switching devices (e.g. switching device S1 in forward mode or switching device S2 in backward mode) with a suitable duty cycle (pulse width), the speed of the electric motor can be controlled. This pulse width modulation (PWM) method is well known and will not be further elucidated herein.

[0055] In the shown embodiment, the motor control unit 34 is further configured to make a decision based on suitable motor parameters and sensor signals (e.g. the current flowing through the electric motor and / or the Hall sensor signal as described above) to determine the actual position of the closure member 2a. This actual position is fed back to determine a deviation between the actual position and the set position 30, based on which the proportional controller can adjust the settings for the electric motor. Of course, in another embodiment, a direct (or other indirect) position sensor can be used instead.

[0056] FIG. 4A to FIG. 4C The results are based on a model-based simulation of a representative electric motor, a representative mechanical drive assembly and a closure member, wherein the mass of the closure member 2a is 10 kg.

[0057] FIG. 4A A graph showing the overshoot of the closure member 2a is shown. The horizontal axis represents time in seconds and the vertical axis represents the overshoot in millimeters, wherein the overshoot is defined as the distance travelled after the safety stop is initiated. In the shown simulation example, the safety stop is initiated at time to (1 on the horizontal axis). Hence, any movement of the closure member 2a in the original direction of movement after to is considered as overshoot.

[0058] Two braking methods are illustrated. The solid line represents the overshoot when a prior art active braking is applied by short-circuiting, which is referred to as active braking mode in the above. The dashed line represents the braking method according to the present application, wherein a regenerative braking mode is initiated and maintained until the closure member 2a actually stops.

[0059] As shown by the solid line, the active braking mode is initiated at time to and the overshoot gradually increases to about 3.3 mm after about 120 ms. Then, the closure member 2a stops and the overshoot remains constant. The regenerative braking mode (dashed line) is initiated at the same time to and the overshoot gradually increases similarly to the active braking mode until about 1.8 mm at time ti. At time ti, the overshoot starts to decrease to reach a value of about 0.5 mm after about 120 ms. Hence, while the active braking mode results in an overshoot of about 3.3 mm, the safety stop according to the present application results in a maximum overshoot of about 1.8 mm, thereby reducing the overshoot by about 1.5 mm. This is a significant reduction.

[0060] FIG. 4B and FIG. 4C The motion of the closing member 2a relative to the electric motor is shown in more detail. In both graphs, the horizontal axis represents time in seconds, and the vertical axis represents speed in meters per second. Furthermore, in both graphs, the solid line represents the motor speed, and the dashed line represents the speed of the closing member (glass panel). FIG. 4B and FIG. 4C The result corresponds to FIG. 4A The result.

[0061] FIG. 4B The results for the active braking mode as a safety stop method are shown. At time t0, the safety stop is initiated, and after a short period for switching the device (which may be as short as 0.4 ms if a MOSFET is used), the motor speed decreases from almost 0.1 m / s (shown in the opposite direction in the figure: -0.1 m / s) to approximately 0 m / s. However, the speed of the closing member decreases very slowly. Although the motor speed drops to zero after approximately 20 ms, it takes approximately 120 ms for the closing member to reach a speed of approximately 0 m / s. During the period when the motor speed is approximately 0 m / s, although the speed of the closing member gradually decreases, the closing member is able to maintain its movement due to the backlash in the mechanical drive assembly.

[0062] exist FIG. 4C The diagram illustrates a safe stopping method according to the present invention. At time t0, a regenerative braking mode is initiated after the aforementioned short period used for switching. FIG. 4B Compared to the active braking mode, the motor speed decreased from -0.1 m / s to 0 m / s at approximately 10 milliseconds to approximately 0.1 m / s at time t1, approximately 30 milliseconds later. Correspondingly, the speed of the closing member decreased even faster. At time t1, approximately 30 milliseconds later, the speed of the closing member decreased to 0 m / s.

[0063] From the moment the motor speed changes direction (at 0 m / s), the electric motor begins to move in the opposite direction, thereby beginning to absorb at least a portion of the clearance in the mechanical drive components.

[0064] At the moment when the speed of the closing member decreases to 0 m / s, the motor speed is approximately 0.1 m / s, and the electric motor can be shut off. The electric motor continues to move further in the opposite direction before coming to a complete stop. During the period when the electric motor stops, the closing member moves in the opposite direction to finally stop after approximately 120 milliseconds.

[0065] FIG. 5 The four-switch mechanism is shown as measured on a commercially available open roof assembly (see [reference]). FIG. 3A The four actual control signals S S1, S S2 , S S3 and S S4 . Thus, FIG. 5 a safety stop method as employed in a commercially available open roof assembly is shown as a comparison example.

[0066] With reference to FIG. 3A and FIG. 5 both, a first control signal S S1 controls a first switching device S1, a second control signal S S2 controls a second switching device S2, a third control signal S S3 controls a third switching device S3 and a fourth control signal S S4 controls a fourth switching device S4.

[0067] In FIG. 5 the horizontal axis represents time in seconds and the vertical axis represents voltage in volts. At about 0 V, the control signal is low and the corresponding switching device is off, i.e. in a non-conductive state. In the illustrated embodiment, at a higher level of e.g. 1 V or higher, the signal is high and the corresponding switching device is on, i.e. in a conductive state.

[0068] In the graph of FIG. 5 three phases are notable and indicated. In a first phase, the electric motor is driven in a normal drive mode, i.e. in a forward mode or in a reverse mode. In a second phase, the electric motor is driven in an active braking mode. In a third phase, the electric motor is driven in a regenerative braking mode, indicated by "reverse". In the first phase, the first switching device S1 is driven by a high frequency control signal S S1 switching between an on state and an off state. As is evident from the high state of the fourth control signal S S4 , the fourth switching device S4 is switched to a conductive state. Both the second control signal S S2 and the third control signal S S3 are low to about 0 V, indicating that the second switching device S2 and the third switching device S3 are in a non-conductive, off state. Thus, the electric motor is driven in a forward mode using pulse width modulation to control the speed of the electric motor.

[0069] At a time t 0,CMP , a safety stop is initiated. The safety stop is started with activation of the active braking mode. The first switching device S1 is switched to non-conductive, as indicated by the first control signal S S1 dropping to a low value of about 0 V, while the third control signal S S3 rises to a high value of about 1 V, switching the third switching device S3 to conductive and short-circuiting the electric motor.

[0070] After a time period of about 13 milliseconds, i.e. at time t 1,CMP , the active braking mode is terminated and a third phase is started. The second switching device (second control signal S S2 is high) is switched on and the third switching device (third control signal S S3 is high). Thus, the reverse mode is started. If the electric motor is still moving in the original forward direction (in the first phase) at the start of the third phase, the third phase starts in the regenerative braking mode. In any case, as soon as the electric motor is stopped, the reverse mode drives the electric motor in the reverse direction to start the movement of the closure member in the opposite direction. Based on the simulation as shown in FIG. 4B and the behavior of the motor speed and the time instances, it can be assumed that in FIG. 5 , the time instance of the second phase and the time instance of the start of the third phase (t 1,CMP ) are intended to stop the electric motor essentially in the second phase before the reversal in the third phase is started. Thus, the third phase is not about stopping the closure member, but about reversing the closure member to release a jammed object, if any.

[0071] Practical tests have shown that the prior art method of the comparative example indeed has a greater overshoot than the method according to the present application. Specifically, in the practical example, the overshoot using the active braking mode amounts to about 2.2 mm, whereas the method according to the present application using the regenerative braking mode results in an overshoot of about 1.1 mm.

[0072] It is noted that the effect of the present application can be different for the original direction of movement. The play in the mechanical drive assembly and specifically in the drive cable can be different depending on whether the mechanical drive assembly is used to push the closure member or to pull the closure member. However, in both cases, the present application provides a reduced overshoot.

[0073] FIG. 6A A method according to the present application is shown. The method starts with a first step S11 in which the closure member is moved in a normal mode, i.e. either forward mode or reverse mode. Then, in a second step, it is determined that a safety stop needs to be initiated. In response and according to the present application, the control unit changes the drive mode of the electric motor from the original mode to a reversal mode, which starts as a regenerative braking mode and automatically changes to a reversal drive mode so that the electric motor is able to absorb at least a part of the play in the mechanical drive assembly. Not earlier than the closure member has actually stopped moving in the original direction of the first step S11, the electric motor is stopped in a fourth step S14.

[0074] FIG. 6B A specific embodiment is shown, in which the first step S11, the second step S12 and the third step S13 are identical to the steps S1, S2 and S3 of the method according to the prior art.FIG. 6A The same applies to the embodiment of Fig. 6. In this embodiment, the next step, i.e. the fifth step S15, comprises determining whether the closure member needs to be reversed after stopping. If it is determined that the closure member does not need to be reversed, the electric motor is stopped after a first reversal time period in a sixth step S16. The first reversal time period corresponds to the time period needed to stop the closure member and is indicated in Fig. 6 as the first reversal time period TR1. This time period can be a predetermined time period or can be determined on the spot based on the movement of the closure member or the speed of the closure member. Note that after the first reversal time period TR1, the closure member can move in the opposite direction due to inertia, as indicated in Fig. 6. Due to this reverse movement, it can not be necessary to actively reverse the closure member. FIG. 4A FIG. 4C However, if it is determined in the fifth step S15 that the closure member needs to move in the opposite direction, a seventh step S17 is started in which the closure member is actively moved in the opposite direction after a first reversal time period TR1 followed by a second reversal time period. This reverse movement can just be a short movement to make sure that an object that can be stuck is released, after which the closure member can stop or the closure member can move further in the opposite direction.

[0075] However, if it is determined in the fifth step S15 that the closure member needs to move in the opposite direction, a seventh step S17 is started in which the closure member is actively moved in the opposite direction after a first reversal time period TR1 followed by a second reversal time period. This reverse movement can just be a short movement to make sure that an object that can be stuck is released, after which the closure member can stop or the closure member can move further in the opposite direction.

[0076] Of course, also embodiments of the application can be adopted in which the fourth step is performed for a time period that is longer than the first reversal time period, such that the closure member is always reversed after the safe stop. FIG. 6A Detailed embodiments of the application are disclosed herein; however, it is to be understood that the embodiments disclosed are merely exemplary of the application which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present application in virtually any appropriately detailed structure. In particular, features described and depicted in the various dependent claims are applicable in combination with any of the features described and depicted in the independent claims, and thus any advantageous combination of the claims is disclosed.

[0077] Furthermore, it is contemplated that the structural elements can be generated by applying three-dimensional (3D) printing technology. Therefore, any reference to a structural element is intended to encompass any computer executable instructions instructing a computer to generate such a structural element by three-dimensional printing technology or similar computer controlled manufacturing technology. Furthermore, any such reference to a structural element is also intended to encompass a computer readable medium carrying such computer executable instructions.

[0078]

[0079] ​​Furthermore, the terms and phrases used herein are not intended to be limiting, but rather to provide an understandable description of the application. The term "a" or "an" is defined as one or more unless indicated otherwise by context. The term "another" is defined as at least a second or more. The terms including and / or having, including their derivatives, are defined as comprising (i.e., open language). The term coupled is defined as connected, although not necessarily directly, although not necessarily directly connected.

[0080] This application having been thus described, it will be obvious that the same can be varied in many ways. Such changes will be considered as falling within the spirit and scope of the application and all such modifications are intended to be included within the scope of the following claims.

Claims

1. An open roof assembly for a vehicle roof, the open roof assembly comprising a movable closure member for selectively covering or at least partially exposing an opening in the roof, an electric motor operably coupled to the closure member via a mechanical drive assembly for moving the closure member, an electric drive unit for providing a supply signal to the electric motor, and a control unit operably coupled to the electric drive unit for controlling the operation of the electric motor, wherein the electric drive unit includes four switching devices in a bridged configuration and wherein the control unit is configured to a. The movement of the closing member is controlled by controlling the operation of the switching device, and b. During the movement of the closing member, a safe stop is caused by immediately reversing the polarity of the supply signal. The control unit is configured to cause a predetermined stop to the movement of the closing member by short-circuiting the electric motor.

2. The open roof assembly of claim 1, wherein the polarity reversal is maintained for at least a first reversal time period, wherein the first reversal time period is selected based on the amount of clearance in the mechanical drive assembly, such that during the first reversal time period, the clearance in the mechanical drive assembly is at least partially absorbed by the reversal of the electric motor, and the movement of the closing member ceases.

3. The open roof assembly of claim 2, wherein the control unit is configured to continue a second reversal period after the first reversal period, wherein during the first reversal period, the movement of the closing member stops, and wherein during the second reversal period, the closing member is controlled to move in the opposite direction.

4. The open roof assembly according to claim 1, wherein the switching device is a solid-state switching device.

5. The open roof assembly according to claim 4, wherein, The solid-state switching device is a transistor.

6. The open roof assembly according to claim 4, wherein, The solid-state switching device is a MOSFET transistor.

7. The open roof assembly according to any one of claims 4-6, wherein the control unit is configured to control the movement of the closing member by applying a pulse width modulation (PWM) control method.

8. The open roof assembly of claim 7, wherein the control unit is configured to determine the actual position of the closing member, and wherein the control unit is configured to apply a closed-loop control method using the determined actual position of the closing member.

9. The open roof assembly of claim 1, wherein the control unit is configured to detect an obstacle in the travel path of the closing member during movement, and to cause the safety stop upon detection of such an obstacle.

10. A method of operating an open roof assembly, the open roof assembly comprising a movable closure member for selectively covering or at least partially exposing an opening in the roof, an electric motor operably coupled to the closure member via a mechanical drive assembly for moving the closure member, an electric drive unit for providing a supply signal to the electric motor, and a control unit operably coupled to the electric drive unit for controlling the operation of the electric motor, wherein the electric drive unit includes four switching devices in a bridged configuration, the method comprising causing the control unit to perform the following steps a. The movement of the closing member is controlled by controlling the operation of the switching device, and b. During the movement of the closing member, a safe stop is caused by immediately reversing the polarity of the supply signal. The control unit is configured to cause a predetermined stop to the movement of the closing member by short-circuiting the electric motor.

11. The method of claim 10, wherein the polarity reversal step is maintained for at least a first reversal time period, wherein the first reversal time period is selected based on the amount of clearance in the mechanical drive assembly, such that during the first reversal time period, the clearance in the mechanical drive assembly is at least partially absorbed by the reversal of the electric motor, and the movement of the closing member stops.

12. A computer software product comprising computer-readable and executable instructions for instructing a computer processor to perform method steps according to any one of claims 10 to 11.

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