GB2433480A

GB2433480A - Cabriolet roof control linked to vehicle speed

Info

Publication number: GB2433480A
Application number: GB0526286A
Authority: GB
Inventors: Simon Breen
Original assignee: Nissan Motor Manufacturing UK Ltd; Nissan Technical Centre Europe Ltd
Current assignee: Nissan Motor Manufacturing UK Ltd
Priority date: 2005-12-23
Filing date: 2005-12-23
Publication date: 2007-06-27
Anticipated expiration: 2025-12-23
Also published as: WO2007071627A1; GB0526286D0; GB2433480B

Abstract

A cabriolet roof movement controller 22 receives a user command input and data representing at least one vehicle operating parameter. The controller 22 comprises a processor programmed to determine vehicle speed and roof movement responses appropriate to the command and the data. It provides outputs for vehicle speed limitation and/or for roof movement control, when appropriate as determined by the processor. Speed control signals may be sent to an engine management system 26 or to a braking system. Override means 22a may be provided so that kicking on an accelerator pedal 34 prevents the folded roof (10 see fig 2) from opening, whilst allowing the vehicle to exceed a first speed limit. The controller reduces the risks of roof damage and vehicle instability.

Description

FOLDING ROOF CONTROLLER

Field of the invention

The present invention relates to the field of folding roof structures for vehicles. In particular, the invention relates to a controller for a roof structure and a method of operating a controller for a roof structure.

Background to the invention

Vehicles, particularly automobiles, having retractable or folding roof structures are well known and are commonly referred to as convertibles' or cabriolets'. The latter term will be used herein for brevity. There are two main types of cabriolet: the soft-top' cabriolet and the hard-top' cabriolet.

The more common type of cabriolet is the soft-top cabriolet which has a roof structure comprising a flexible fabric material stretched over a folding frame. The frame is collapsible or extendable between folded and unfolded states of the roof, the flexible material folding or creasing as the frame collapses into the folded state. The folded roof structure is stored in a roof storage compartment behind the seats of the vehicle, most commonly ahead of or above a luggage compartment in front-engine vehicles. The roof storage compartment may then be closed by a rigid movable cover or by a soft cover removably attachable over the folded roof structure.

The hard-top cabriolet is rapidly gaining in popularity due to its superior insulation, safety and security characteristics. Hard-top cabriolets include a so-called retractable hard-top' (RHT), this being a roof structure formed of two or more rigid panels that are connected together for relative movement. Linkages, such as pivots or parallelogram linkages, support the panels and permit movement of the panels between a first, unfolded state of the roof structure and a second, folded state.

In the unfolded state, the RHT roof structure covers the passenger compartment or cabin of a hard-top cabriolet giving the appearance of a conventional fixed-roof vehicle. In the folded state, the roof structure is folded such that the panels lie beside each another as compactly as possible. During movement between the unfolded and folded states, each panel moves relative to each other about the linkages between them, often in a clam-shell' pivoting movement.

Again, the folded RHT roof structure is stored behind the seats of the vehicle in a roof storage compartment. Most commonly in front-engine vehicles, that compartment is an upper region of a luggage compartment whose lid, hatch, door or tailgate is arranged to open to permit access of the folded roof structure thereto. Such hard-top cabriolet vehicles are well known: an example of a vehicle having a RHT, and the operation thereof, is described in US Patent No. 6,299,234.

Substantially all hard-top cabriolets and many soft-top cabriolets employ actuators such as hydraulic rams to cycle the roof between the folded and unfolded states and to move associated vehicle panels during that movement of the roof, such as a roof storage compartment cover. A roof control system responds to user input to co-ordinate the numerous actions necessary to fold or to unfold the roof and to latch the roof in the desired state. For example, the roof control system may be operated by a driver pressing a roof-up or roof-down switch located in the vehicle cabin, or on a remote-control key fob.

When partially unfolded during operation, a folding roof is vulnerable to wind damage due to vehicle motion if the vehicle accelerates to excessive speeds. A partially unfolded roof may also adversely affect handling characteristics by raising the centre of gravity of the vehicle or by damaging its aerodynamics. Consequently, roof control systems routinely include a deactivation or warning means that prevents roof motion or that gives a warning such as sounding a buzzer when the vehicle is moving, or when the vehicle speed exceeds a predetermined threshold of up to say 50 kph. The deactivation or warning means may be directly responsive to vehicle speed or motion, for example by acting on information from the vehicle transmission, speedometer or engine management system. Alternatively, the deactivation or warning means may simply respond to whether or not the vehicle is capable of motion, for example if an attempt is made to move the roof when the parking brake is off or when a gear has been selected in the vehicle transmission.

So, present roof control systems either stop roof motion or notify the vehicle user in some manner (e.g. by sounding a buzzer) that operation of the roof is inappropriate.

Unfortunately if roof motion is stopped in mid-transit while a vehicle is moving, that perpetuates the reason for stopping the roof, i.e. the possibility of roof damage and vehicle instability. Moreover, paradoxically, it does so when the roof and the vehicle may be at their most vulnerable to those threats. Also, the vehicle occupants may be soaked by a sudden downpour of rain if the roof movement stops before the roof is fully unfolded and closed.

If the driver chooses to accelerate despite the roof being partially unfolded, the roof could be damaged and the vehicle may become unstable. However, there may be instances where the driver has to accelerate for safety reasons or simply because traffic flow makes it undesirable for the vehicle to remain stationary, or below a deactivation threshold speed, while waiting for the roof to complete its movement.

It is an object of the present invention to provide a folding roof control arrangement that substantially overcomes or mitigates the above mentioned problems.

According to a first aspect of the present invention, there is provided a cabriolet roof controller, the controller comprising inputs for receiving a user command and data representing at least one vehicle operating parameter; a processor programmed to determine vehicle speed and roof movement responses appropriate to said command and data; and outputs for outputting a vehicle speed control signal and a roof movement control signal as determined by the processor.

The present invention provides a roof controller that is in communication with the roof structure drive means (i.e. the roof structure drive mechanism that raises and lowers the roof structure between a first, unfolded position in which the roof covers the passenger compartment and a second, folded position in which the roof structure is stored) and also with a means for limiting the speed of the vehicle.

In use, the roof controller receives a user initiated request (the user command) to either raise or lower the roof structure. The controller first determines at least one vehicle operating parameter and then, based on this parameter, outputs a vehicle speed control signal to control the speed of the vehicle and a roof movement control signal to the roof structure drive means to control the movement of the roof.

The vehicle speed control signal may conveniently be output to an engine management system to limit vehicle speed by restricting the speed or power output of the engine.

Alternatively, however, the vehicle speed control signal may be output to the transmission system of the vehicle or to its braking system in order to control the speed of the vehicle.

The present invention therefore acts to modif' or limit the speed of the vehicle in order to allow the roof structure to operate. This system is in contrast to prior art arrangements which seek to prevent roof movement above certain speeds.

Conveniently, the vehicle speed control signal is a signal to limit the speed of the vehicle.

Conveniently, the vehicle operating parameter can either be the vehicle speed or the vehicle's acceleration as may, for example, be determined by sensing the vehicle's accelerator pedal position.

Preferably, if the vehicle operating parameter is below a first threshold value, then the vehicle speed control signal is a signal to limit the speed of the vehicle to the first speed threshold value. Conveniently, the controller may additionally output a roof movement control signal to raise or lower the roof structure.

This feature defines the conditions under which the roof can safely be raised and lowered without risk of damage to either the roof structure or the vehicle. If the vehicle is operating below a certain threshold then the roof will be activated and the vehicle speed will be limited until the roof structure has completed its transition.

In the case where the vehicle operating parameter is the speed of the vehicle, then the roof controller will determine the speed of the vehicle and, if the speed is below a certain value, it will output a vehicle speed control signal to limit the vehicle speed to a first speed threshold value. The controller may also additionally output a roof movement control signal to raise/lower the roof. Alternatively, the roof movement control signal may be delayed until the vehicle speed is within the first speed threshold value. In this case, the first threshold value of the vehicle operating parameter is preferably equal to the first speed threshold value.

In the case where the vehicle operating parameter is the acceleration of the vehicle, then the roof controller will determine the acceleration of the vehicle and, if the acceleration is below a certain threshold value, it will output a vehicle speed control signal to limit the vehicle speed to a first speed threshold value and will output a roof control signal to raise/lower the roof.

As a further alternative, the roof controller may determine both the speed of the vehicle and the acceleration of the vehicle. If the roof controller determines that the vehicle speed is below the first speed threshold value but that, at the current speed and acceleration of the vehicle, there will be insufficient time to complete a roof transition, it may output a roof movement control signal to prevent roof movement.

If the vehicle user attempts to operate the roof structure above the first threshold value, then, preferably, the roof controller sends a vehicle speed control signal to limit the speed of the vehicle to a second speed threshold. The controller may also output a roof movement control signal depending on the position of the roof structure. For example, if the roof is in a fully raised or lowered position then the roof movement control signal is a signal to stop movement of the roof structure. However, if the roof structure is midway in its transition from open to closed (or vice versa) then it may be preferable to complete the roof movement. The controller may therefore send a first roof movement control signal to complete the roof transition and then a further control signal to prevent further roof movement.

As described above, the roof controller of the present invention acts to limit the speed of the vehicle (to either a first or second speed threshold value) in order to allow the roof to operate or to prevent significant damage to the roof structure or vehicle.

It may be the case, however, that a user wishes to override the speed limitation commands output from the roof movement controller. This could be because the vehicle is in an inconvenient or dangerous position and needs to exceed one or more of the speed threshold values to manoeuvre out of that position or to keep up with traffic flow.

Preferably, therefore, the roof controller further comprises override means arranged in use to override the vehicle speed control signals. Such an override means could, conveniently, be operated by a dedicated control switch or lever or, more preferably, could be linked to the position of the vehicle's accelerator pedal such that a kick-down action on the pedal activates the override means.

Conveniently, the override means will be arranged to allow the vehicle speed to exceed each of the first and second speed threshold values in turn.

Although the vehicle operating parameter threshold values and the speed threshold values can be fixed, they can conveniently be dependent on the position of the roof structure between the first and second roof positions.

Conveniently, the roof controller further comprises means for determining the at least one vehicle operating parameter. For example, an engine management system could provide data relating to the vehicle operating parameters to the roof controller or, alternatively, the roof controller could receive data input from the vehicle transmission, braking system, wheels or speedometer. The vehicle operating parameter could also be provided from an extra-vehicular positioning system such as a GPS system.

Conveniently, the roof controller further comprises means for activating a roof transition. For example, the user may operate a button or switch within the car or on a remote-controlling key fob to effect operation of the roof structure. Alternatively, roof activation could be voice activated.

As noted above, both the position of the roof structure and also the vehicle speed affect whether the roof may be operated safely. Preferably, a look-up table may be used to store information relating to the operation of the roof as a function of vehicle speed and roof position.

The present invention may also be expressed as a method of operating a cabriolet roof, the method comprising receiving a request from a user to move the roof and determining at least one vehicle operating parameter; outputting a vehicle speed control signal to control the speed of the vehicle in dependence upon the at least one vehicle operating parameter; and signalling a roof structure drive means to control movement of the roof structure in dependence upon the at least one vehicle operating parameter..

It is noted that preferred features relating to the method of the present invention are described above in relation to the first aspect of the invention The invention extends to a cabriolet roof comprising a folding roof structure and a roof controller according to the first aspect of the invention, and to a cabriolet vehicle having such a roof The invention may also be expressed as a data carrier comprising a computer program to implement the method of the present invention.

Brief description of drawings

The present invention will now be described, by way of example only, with reference to the following figures in which: Figure 1 illustrates a known folding roof structure for a vehicle in its unfolded position; Figure 2 shows the roof structure of Figure 1 in its folded position; Figure 3 illustrates a roof control system incorporating a roof controller according to an embodiment of the present invention; Figure 4 is a flow chart illustrating the operation of the system and roof controller of Figures 3; and Figure 5 is a graph according to a further embodiment of the present invention illustrating how the operation of the roof controller varies in dependence upon the speed of the vehicle and the roof position.

Detailed description of the preferred embodiments of the invention It is noted that throughout the drawings like numerals have been used to denote like features.

Referring firstly to Figures 1 and 2, a known folding roof structure for a vehicle is shown generally at 10. Figures 1 and 2 depict a hard-top cabriolet in which the roof structure is formed of two main parts, a roof part 12 and a rear-window part 14. In a first, closed or unfolded position of the roof structure 10, as illustrated in Figure 1, the roof part 12 is oriented generally horizontally and a front edge region 13 thereof engages with a frame 15 of the vehicle windscreen. In this position, the rear-window part 14 and the roof part 12 cover the cabin or passenger compartment 6 of the vehicle.

In the case of the hard-top cabriolet shown in Figure 1, both the first and second parts 12, 14 are substantially rigid and are generally formed from metal, glass or similarly rigid materials so as to give the appearance, when in the first, unfolded position, that the vehicle is a conventional fixed-roof vehicle and not a cabriolet.

In the case of a soft-top cabriolet, not shown in Figure 1, the roof structure is formed from a flexible fabric material mounted on substantially rigid but foldable frame members.

The roof structure 10 is arranged to be moved or folded from the first unfolded position shown in Figure 1 to a second, open or folded position illustrated in Figure 2. A linkage (not shown) is provided which allows the rear-window part 14 to pivot in a rearward direction (clockwise in the drawings) about a pivot point 17 over an arc of approximately 900. This pivoting movement is achieved by a positive drive mechanism (not shown) drivingly connected to the linkage.

As the rear-window part 14 pivots upon folding the roof structure 10, it carries with it the roof part 12. The nature of the linkage and the pivoting connection between the two parts 12, 14 means that the roof part 12 remains substantially horizontal throughout the rearward folding movement of the roof structure 10. The folding movement of the roof structure 10 is such that when the rear-window part 14 has pivoted through its full range of movement, the entire passenger compartment 6 is uncovered, as illustrated in Figure 2.

The roof structure 10 is stored in its second, folded position within a roof storage compartment 1 8a behind the passenger compartment 6 of the vehicle. In front-engined vehicles such as that illustrated, the roof storage compartment 1 8a is typically an upper part of the luggage compartment 1 8b of the vehicle, and is not separated or divided therefrom or otherwise compartmentalized. A path for movement of the folded roof structure 10 into the roof storage compartment 1 8a is cleared by opening a rearwardly-hinged trunk lid or tailgate 19 which provides access to the roof storage compartment 1 8a.

On folding, the folded roof structure 10 is moved into the roof storage compartment 1 8a by the aforementioned positive drive mechanism. Such roof structures, and the construction and operation thereof, are well known and are described, for example, in US Patent No. 6,299,234 as aforesaid. As such, further details of roof structures of this type are not included herein but will be well understood by those skilled in the art.

In order to avoid damage to the components of the roof structure 10, a roof controller (not shown in Figures 1 and 2) controls the operation of the folding roof based on the vehicle speed. In general, the folding roof will function only when the vehicle is stationary or moving at a low speed. A few vehicles will allow roof operation up to vehicle speeds of around 50 kph. However, most folding roofs will not operate if the vehicle exceeds a slow walking pace and many folding roof systems require the vehicle to be stationary or incapable of movement before the folding roof can function.

The above described prior art roof control mechanism suffers from a number of disadvantages which have already been described in the background section above. In particular, during transition of a folding roof from open to closed, or vice versa, the roof will be susceptible to wind damage caused by the vehicle's movement. Also, in the event that the vehicle exceeds the maximum allowed speed for roof transition, the roof may be held in a partially openedlclosed state which may adversely affect vehicle handling characteristics and will further increase the risk of damage to the roof.

In response to these and other disadvantages of the prior art folding roof systems, the Applicant has developed an improved system which alleviates or reduces some or all of these problems.

Referring to Figure 3, a roof retraction system incorporating a roof controller according to an embodiment of the present invention is shown generally at 20. The system comprises a roof controller 22 which is operably connected to a roof drive mechanism 24 that is used to raise and lower the roof 10 between the first, unfolded position shown in Figure 1 (roof up or closed position) and the second, folded position shown in Figure 2 (roof down or open position).

The roof controller 22 is also operably connected to an engine management system 26 and a user-operable roof control switch 28. The roof controller 22 is also connected to a visual display device 30 (e.g. a light or series of lights or alternatively a message display screen) and an audible notification device (e.g. a sounder such as a buzzer) 32.

Accelerator position 34 and vehicle speed 36 are input into the engine management system 26, from which that information may be derived by the roof controller 22.

In use, the roof controller 22 receives a command input 38 from a user via the control switch 28 to either raise the roof 10 (if the roof is currently in its folded position as shown in Figure 2) or to lower the roof 10 (if the roof is currently in its unfolded position as shown in Figure 1). The speed of the vehicle is input (40a, 40b) to the controller 22 via the engine management system 26.

If the vehicle is stationary or its speed is low enough (i.e. it is below a first threshold value) that the roof can be raised or lowered without any damage to the roof or other significant harmful effect on the vehicle, the roof controller 22 sends a first roof control signal 42 to the roof drive mechanism 24 to either raise or lower the roof as appropriate.

The roof controller 22 additionally sends a first engine control signal 44 to the engine management system 26 to limit the vehicle speed to the first speed threshold value.

The roof 10 is then raisedllowered and the position of the roof during its transition from open to closed (or vice versa) is communicated 46 by the roof drive mechanism 24 to the roof controller 22.

During the transition, the engine management system 26 limits the vehicle speed to a first speed threshold value. This ensures that the driver of the vehicle cannot inadvertently accelerate to a speed that would cause wind damage to the roof mechanism/roof structure (24/10) or significantly affect vehicle performance.

The roof controller 22 may additionally output a notification (48, 50) to the vehicle user that the vehicle speed has been, or will be, limited by means of the visual display device and/or by means of the sounder 32. Visual notification may involve a changing light display or a message displayed on a screen on, for example, the instrument display of the vehicle.

If the vehicle speed is above the first speed threshold value when the vehicle user operates the control switch 28, then the roof controller 22 will prevent the roof 10 from opening/closing, i.e. no signal or a no action required' signal will be sent to the roof drive mechanism 24. In this event, the roof controller 22 may send an appropriate notification message to the user either via the sounder 32 or the display device 30 or via a combination of both.

It may be the case that, having initiated a roof transition below the first speed threshold value, the vehicle user decides that he needs or wishes to exceed the threshold speed.

This could be for various reasons. For example, the roof transition may be initiated while the vehicle is stationary at traffic signals. If the signals change such that traffic flow resumes before the roof transition is complete, the user may decide to exceed the first speed threshold value in order not to impede traffic flow. The roof control system is therefore optionally provided with override means 22a to allow the vehicle user to override the speed limit imposed by the controller/engine management system such that the vehicle speed may exceed the first threshold value.

The override means 22a may be controlled by the control switch 28. However, more conveniently, the override means 22a is linked to the accelerator pedal position 34. In that case, to override the first speed threshold value, the vehicle user may kick down' on the accelerator pedal (e.g. by depressing the accelerator pedal past a certain threshold such as 33% of the maximum accelerator position). This override action is communicated (52a, 52b) via the engine management system 26 to the roof controller 22.

Once an override of the system has been initiated by the user, the roof controller 22 sends a second roof control signal 54 to the roof motor mechanism 24 to stop the roof transition (e.g. to stop the roof transition partway between the open and closed positions). The roof controller 22 additionally sends a second engine control signal 56 to the engine management system 26 to allow the vehicle speed to exceed the first speed threshold value.

The roof controller 22 may allow the user to operate the vehicle/engine without limitation at this stage or more preferably the second engine control signal 56 sent to the engine management system 26 may instruct the management system to limit the vehicle speed to a second speed threshold value. Upon receipt of this second signal 56, the engine management system will either limit the vehicle speed to the second threshold value or allow the engine to operate without limitation depending on the requirements of the roof retraction system.

The second speed threshold value is set at a value which allows the vehicle to move, with the roof in a fixed position between the open and closed positions but with minimal risk of adverse effects to the vehicle or its handling characteristics.

The roof controller may once again send notification (48, 50) to the vehicle user of the second speed threshold value by means of one or both of the visual display means 30 and sounder 32.

If the vehicle speed is above the second speed threshold value when the vehicle user operates the control switch 28 then the roof controller 22 will prevent the roof 10 from opening/closing, i.e. no signal or a no action required' signal will be sent to the roof drive mechanism 24. In this event, the roof controller 22 will send an appropriate notification message to the user either via the sounder 32 or display device 30 or a combination of both.

Again, it may be case that, having exceeded the first speed threshold value, the vehicle user needs or wishes to exceed the second speed threshold value. Exceeding the second speed threshold value will likely cause damage to the roof mechanism 24, roof structure and also the vehicle and so it is envisaged that exceeding the second speed threshold will only occur in extreme circumstances (e.g. if the vehicle is in a position of danger).

The roof retraction system 20 (and the override means 22a) may therefore allow the vehicle user to override the speed limitation for a second time. This second override may be provided once again by means of a kick-down action on the accelerator pedal 34 distinct from the action that overrides the first speed threshold (e.g. by depressing the accelerator past 66% of its maximum position, or by depressing it to the end of its range of travel).

Once a second override of the system has been initiated by the user, the roof controller 22 sends a third roof control signal 60 to the roof drive mechanism 24 to ensure that the roof transition remains stopped. The roof controller 22 additionally sends a third engine control signal 62 to the engine management system 26 to allow the vehicle speed to exceed the second speed threshold value. Upon receipt of this third roof control signal 62, the engine management system 26 will allow the engine to operate without limitation.

The transition from the second speed threshold operating condition to the unlimited operating condition may be notified 48, 50 to the user by the roof controller 22 via the visual display means 30 or sounder 32.

Referring to Figure 4, a flow diagram is shown depicting the processesdescribed above in relation to Figure 3.

Roof movement is initially requested 70 by the user, by operating the control switch 28.

Assuming the vehicle speed is below the first speed threshold value, then the roof controller 22 will open the roof 10 and signal the engine management system 26 to limit the vehicle speed to the first threshold value (Stage 1).

If the vehicle speed is greater than the first speed threshold value when the user requests a roof transition or if alternatively the user overrides the speed limitation imposed in Stage 1 (e.g. by depressing the accelerator past 33% of its full acceleration position), then the system moves 72 to Stage 2 in which the vehicle is limited to a second speed threshold value and the roof transition is preferably stopped or prevented. Additionally a warning is notified to the user by either the sounder 32 or the visual display device 30 (or alternatively by both devices).

If the vehicle speed is greater than the second speed threshold value when the user requests a roof transition or alternatively if the user overrides the speed limitation imposed in Stage 2 (e.g. by depressing the accelerator past 66% of its full acceleration position), then the system moves 74 to Stage 3 in which vehicle speed is not limited. In Stage 3, roof movement is preferably prevented and a second level of warning is notified to the user.

If the system is in Stage 3 and the accelerator position 34 drops below the threshold value that initiates the second override or alternatively if the vehicle speed drops below the second speed threshold then the roof retraction system 20 returns 76 to Stage 2.

If the system is in Stage 2 and the accelerator position 34 drops below the threshold value that initiates the first override or alternatively if the vehicle speed drops below the first speed threshold then the roof retraction system returns 78 to Stage 1.

Although the first and second speed threshold values can be fixed, it is noted that varying values are possible for the two thresholds dependent upon the position of the roof and the vehicle speed. If the roof is near either end of its range of movement and so close to being fully open or closed, a higher speed may be safely permissible than when the roof is near the middle of its range of movement and so is relatively upright where it will catch the airflow particularly badly and may upset the balance of the vehicle.

Table 1 below shows an example according to a further embodiment of the present invention of the dependence of the threshold values on the speed of the vehicle and the roof position.

Position of Roof 10 First Speed Threshold Second Speed Threshold (and Roof Trunk lid 19) Value (kph) Value (kph) 1) Roof down, trunk lid No speed restriction No speed restriction down (i.e. roof in position necessary necessary shown in Fig 2) 2) Roof in folded position, 20 40 trunk lid open 3) Trunk lid open, Roof 10 25 1/3d through transition 4) Trunk lid open, Roof 5 20 2/3d through transition 5) Trunk lid open, Roof in 20 40 engagement with frame 15 6) Roof up (i.e. roof in No speed restriction No speed restriction position shown in Fig 1) necessary necessary

Table 1

Table 1 is represented graphically in Figure 5. The maximum vehicle speed depicted is kph although this is only for illustration purposes.

In the region 80 below the first speed threshold line, the roof controller will allow roof movement. The vehicle speed will be limited to the value indicated by the first speed threshold line for the roof position at any given time.

In the region 82 between the first speed threshold line and the second speed threshold line, the roof controller 22 will prevent roof movement. Vehicle speed will be limited to the speed value indicated by the second speed threshold line for whatever position the roof is in.

In the region 84 above the second speed threshold line, the vehicle/engine speed is not limited in any way.

It will be understood that the embodiments described above are given by way of example only and are not intended to limit the invention, the scope of which is defined in the appended claims. It will also be understood that the embodiments described may be used individually or in combination.

As an example of variants within the broadest concept of the invention, it is preferred that roof movement is stopped or prevented when the vehicle speed exceeds one of the aforesaid thresholds, but this is not essential. For example, there may be advantages in permitting roof movement to continue once the driver has chosen to exceed a vehicle speed threshold with knowledge of the risks involved. This may apply particularly if the roof has already moved past its most vulnerable position such that continued movement would have the effect of decreasing rather than increasing the risks arising from vehicle movement while the roof is in transition The preceding description of preferred embodiments requires that vehicle speed is known to and derived from the engine management system. However it is possible to deduce vehicle speed by other means, such as from sensors associated with the vehicle transmission, braking system, wheels or speedometer. It is even possible to deduce vehicle speed from extra-vehicular positioning systems such as satellite-based global positioning systems or roadside beacons. Any such means of speed measurement is contemplated within the broad inventive concept.

Similarly, whilst it is preferred to use the engine management system to limit vehicle speed by restricting the speed or power output of the engine, this is not essential to the invention in its broadest sense. For example, speed may be limited by the transmission system of the vehicle or by its braking system.

Claims

Claims 1. A cabriolet roof movement controller, the controller

comprising inputs for receiving a user command and data representing at least one vehicle operating parameter; a processor programmed to determine vehicle speed and roof movement responses appropriate to said command and data; and outputs for outputting a vehicle speed control signal andlor a roof movement control signal as determined by the processor.

2. A roof controller as claimed in Claim 1, wherein the vehicle speed control signal is a signal to limit the speed of the vehicle.

3. A roof controller as claimed in Claim 1 or Claim 2, wherein the vehicle operating parameter is the speed of the vehicle.

4. A roof controller as claimed in Claim 1 or 2, wherein the vehicle operating parameter is the vehicle acceleration requested by the driver.

5. A roof controller as claimed in any preceding Claim wherein, if the vehicle operating parameter is below a first threshold value then the vehicle speed control signal is a signal to limit the speed of the vehicle to the first speed threshold value and the roof control signal is a signal to raise or lower the roof structure.

6. A roof controller as claimed in claim 5, wherein the controller additionally outputs a roof movement control signal to raise or lower the roof structure.

7. A roof controller as claimed in either of Claims 3 or 4 wherein, if the vehicle operating parameter is above a first threshold value and below a second threshold value, then the vehicle speed control signal is a signal to limit the speed of the vehicle to the second speed threshold value.

8. A roof controller as claimed in claim 7, wherein the controller additionally outputs a roof movement control signal to stop movement of the roof structure.

9. A roof controller as claimed in claim 7, wherein the controller is arranged to output a first roof movement control signal to complete movement of the roof structure to its raised or lowered position and a second roof movement control signal to prevent further roof movement.

10. A roof controller as claimed in any of Claims 2 to 9, further comprising override means arranged in use to override the vehicle speed control signal 11. A roof controller as claimed in Claim 10 when dependent on Claim 5, wherein the override means is arranged to allow a vehicle user to exceed the first speed threshold and to limit the speed of the vehicle to the second speed threshold.

12. A roof controller as claimed in Claim 10 when dependent on any of Claims 7 to 9, wherein the override means is arranged to allow a vehicle user to exceed the second speed threshold value.

13. A roof controller as claimed in any of claims 10 to 12, wherein the controller is operably connected to a user operable control switch within the vehicle such that in use the control switch activates the override means.

14. A roof controller as claimed in any of claims 10 to 12, wherein vehicle accelerator pedal position is input into the controller such that in use a kickdown action on the accelerator pedal activates the override means.

15. A roof controller as claimed in any of claims 5 to 14, wherein the speed threshold values are dependent on the position of the roof structure between the first and second roof positions.

16. A roof controller as claimed in any preceding Claim, wherein the data representing at least one vehicle operating parameter is input to the controller from an engine management system.

17. A roof controller as claimed in any of claims 1 to 15, wherein the data representing at least one vehicle operating parameter is input to the controller from a sensor associated with one or more of the following: vehicle transmission; vehicle braking system; vehicle wheels; vehicle speedometer.

18. A roof controller as claimed in any of claims 1 to 15, wherein the data representing at least one vehicle operating parameter is input to the controller from an extra-vehicular positioning system.

19. A roof controller as claimed in any preceding Claim, wherein the user command is input to the controller from a user operable control switch within the vehicle.

20. A roof controller as claimed in Claim 4, wherein, the vehicle acceleration requested by the driver is determined from the accelerator pedal position.

21. A roof controller as claimed in any preceding Claim, further comprising a look-up table for storing roof actions as a function of roof structure position and vehicle operating parameter.

22. A method of operating a cabriolet roof movement controller comprising receiving a request from a user to move the roof and determining at least one vehicle operating parameter; outputting a vehicle speed control signal to control the speed of the vehicle in dependence upon the at least one vehicle operating parameter; andlor signalling a roof structure drive means to control movement of the roof structure in dependence upon the at least one vehicle operating parameter.

23. A cabriolet roof comprising a folding roof structure and a roof controller according to any of claims Ito 21.

24. A vehicle comprising a folding roof structure and a roof controller according to any of claims 1 to 21.

25. A method of operating a cabriolet roof structure for a vehicle comprising receiving a request from a user to move the roof and determining at least one vehicle operating parameter; controlling the speed of the vehicle in dependence upon the at least one vehicle operating parameter; and/or controlling the movement of the roof structure in dependence upon the at least one vehicle operating parameter.

26. A data carrier comprising a computer program arranged to configure a roof controller to implement the method according to claim 22.

27. A data carrier comprising a computer program arranged to configure a roof to implement the method according to claim 25.

28. A cabriolet roof controller substantially as hereinbefore described with reference to any one of Figures 3 to 5 of the accompanying drawings.