# Patent

## Title
Power split tailgate system and method

## Abstract

A power split tailgate system is provided that allows each of an upper and a lower tailgate door to be simultaneously or independently driven between open and closed positions. The tailgate system may be operated in a chauffer mode where the lower tailgate door is opened to allow for the storage of luggage and other materials and in a manner that limits exposure of the passenger compartment.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. application Ser. No. 13/264,606 which is 371 National Stage entry of PCT/EP2010/054914, filed Apr. 14, 2010, which is a continuation of U.S. application Ser. No. 12/425,049, filed Apr. 16, 2009, now U.S. Pat. No. 8,174,146. The entire contents of these earlier applications are hereby incorporated by reference.


FIELD OF THE INVENTION
The present invention relates to a power split tailgate system and method of controlling the same.
BACKGROUND OF THE INVENTION
A five door vehicle, such as but not limited to a station wagon, sport utility vehicle (SUV), cross-over vehicle (XUV), van, etc., may include a tailgate at a rear of the vehicle. The tailgate gate may include one or more doors that open to provide access to a passenger compartment. When opening the tailgate, the passenger compartment may be exposed to the outside elements in a manner that can cause discomfort to the vehicle occupants, especially those sitting in the rear.
Exposing occupants to the outside conditions may be unfavourable, especially when the vehicle is used in hot or cold climate countries or ones that suffer from poor air quality. This situation may be considered to be especially unacceptable in a chauffer market sector where occupants are paying a chauffer to drive them to a particular destination. If the tailgate needs to be opened, such as to place into or remove items from the vehicle luggage space, occupants may be exposed to the elements, effecting the conditioned air environment inside the cabin.
SUMMARY OF THE INVENTION
It is an aim of the present invention to address the aforementioned issue. Other aims and advantages of the invention will become apparent from the following description, claims and drawings.
Aspects of the invention therefore provide a system, a method and a vehicle as claimed in the appended claims.
According to another aspect of the invention for which protection is sought, there is provided a power split tailgate system for use with a vehicle having a rear storage area accessible through a rearward opening, wherein the rear storage area is defined as a volume extending depthwise from a rear seat to the rearward opening, widthwise from one interior passenger door panel to an opposed interior passenger door panel, and heightwise from a ceiling to a floor, the system comprising:

    
    
        an upper tailgate having an electric motor to articulate an upper door relative to the rearward opening, wherein the upper door articulates between an upper open position and an upper closed position, the upper door covering an upper portion of the rearward opening in the upper closed position and providing access to an upper portion of the rear storage area in the upper open position;
        a lower tailgate having an electric motor to articulate a lower door relative to the rearward opening, wherein the lower door articulates between a lower open position and a lower closed position, the lower door covering a lower portion of the rearward opening in the lower closed position and providing access to a lower portion of the rear storage area in the lower open position; and
        a controller configured to independently control the electric motors of the upper and lower tailgates according to a chauffeur mode that permits full access to the lower portion of the rear storage area while at the same time limiting exposure of the upper portion of the rear storage area, the chauffer mode characterized as a sequence by which the upper door is partially articulated from the upper closed position toward the upper open position before the lower door begins to fully articulate from the lower closed position to the lower open position.
    
    


In an embodiment the system comprises a compartment cover extending approximately from the rear seat to the upper and lower doors, the compartment cover separating the rear storage area into the upper storage area and the lower storage area.
In an embodiment, the upper and lower doors are sized such that the partial articulation of the upper door in chauffeur mode does not require a bottom of the upper door to articulate above the compartment cover.
In an embodiment, the motor used to articulate the lower door is positioned within a watertight interior of the lower door.
In an embodiment, a partial angle of articulation required for partially articulating the upper door in the chauffeur mode is less than 25% of an angle of articulation required to fully articulate the upper door from the upper closed position to the upper open position.
In an embodiment, the controller is further configured to operate according to an upper mode where the upper door is articulated between the upper open and closed positions while the lower door remains in either one of the lower open and closed positions.
In an embodiment, the controller is further configured to operate according to a dual mode where the upper and lower doors are simultaneously articulated between open and closed positions.
The system may comprise an electric motor for retracting a compartment cover included within the rear storage area toward the rear seat while the upper and lower doors are simultaneously being articulated according to the dual mode.
The system may comprise a remote control configured to issue wireless signals to the controller that instruct the controller to open and close one or both of the upper and lower doors.
In an embodiment, door opening and closing executed by the controller in response to at least one of the wireless signals received from the remote control is determined from user input to a human machine interface (HMI) included within the vehicle.
In an embodiment, the remote control issues the same wireless signals to the controller regardless of the user input to the HMI.
According to another aspect of the invention for which protection is sought, there is provided a method of articulating a power, split tailgate system of a vehicle, wherein each of a upper tailgate door and a lower tailgate door are electrically movable between an open position and a closed position, the method comprising in the event both of the upper and lower tailgate doors are in the closed position and a chauffer mode command is received, automatically executing a chauffer mode door control sequence in which; (a) the upper tailgate door is moved a portion of a distance required to move to the open position, the distance being sufficient for a top of the lower tailgate to clear a bottom of the upper tailgate; and (b) the lower tailgate is moved to the open position after the top of the lower tailgate is clear of the bottom of the upper tailgate.
The method may comprise, in the event the lower tailgate door is in the open position and the upper tailgate door is in the closed position when an open upper command is received, automatically returning the lower tailgate door from the open position to the closed position.
The method may comprise, in the event the lower tailgate door was manually articulated to the open position when the open upper command is received, automatically moving the upper tailgate door to the open position without moving the lower tailgate door.
The method may comprise, in the event the lower tailgate door and the upper tailgate door are in the open position when the chauffer mode command is received, automatically closing the upper tailgate door without closing the lower tailgate door.
The method may comprise, determining a need to execute the chauffer mode door control sequence in place of a previously programmed door control sequence in the event that prior user interaction with a human machine interface (HMI) reprogrammed a controller to execute the chauffer mode door control sequence in place of the previously programmed command.
According to a further aspect of the invention for which protection is sought, there is provided a method of articulating a power, split tailgate system of a vehicle, wherein each of a upper tailgate door and a lower tailgate door are electrically movable between an open position and a closed position, the method comprising displaying a plurality of door control sequences within a human machine interface (HMI) of the vehicle, determining user selection of a first door control sequence from the plurality of displayed door control sequences, programming whether one or both of the upper and lower tailgate doors are to be articulated in response to wireless receipt of a door control message based on control parameters specified within the first door control sequence, and executing the first door control sequence upon receipt of the door control message.
The method may comprise, if the first door control sequence results in both of the upper and lower tailgate doors being moved from the closed position to the open position, initially moving the upper tailgate door toward the open position prior to moving the lower tailgate door toward the open position.
The method may comprise, upon subsequent user selection of a second door control sequence from the number of door control sequences, executing the second door control sequence in place of the first door control sequence upon subsequent receipt of the door control message.
The method may comprise associating the first door control sequence with a first user associated with a first remote control and associating the second door control sequence with a second user associated with a second remote control, configuring each of the first and second remote controls to issue an identifier with the door control message that indicates whether the first or second remote control is transmitting the door control message, and executing the first or second door control sequence depending on whether the identifier associated with the first or second remote control is received with the door control message.
Within the scope of this application it is envisaged that the various aspects, embodiments, examples, features and alternatives set out in the preceding paragraphs, in the claims and in the following description and drawings may be taken independently or in any combination thereof. Features described with reference to one embodiment are applicable to all disclosed embodiments, except where there is incompatibility of features.
The present invention will now be described, by way of example only, with reference to the accompanying drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a split tailgate system embodying one non-limiting aspect of the present invention;
FIG. 2 illustrates articulation of an upper tailgate door to an open position in the system of FIG. 1;
FIG. 3 illustrates articulation of both of an upper and lower tailgate door to an open position in the system of FIG. 1;
FIGS. 4a-4b illustrate articulation of a lower tailgate door to an open position in the system of FIG. 1;
FIG. 5 illustrates a flowchart of a method of controlling the split tailgate system wherein open tailgate doors are returned to a closed position in accordance with one non-limiting aspect of the present invention;
FIG. 6 illustrates a flowchart of a method of controlling the split tailgate system wherein tailgate door control sequences are determined according to whether any open doors were opened manually or electronically in accordance with one non-limiting aspect of the present invention; and
FIGS. 7A and 7B together comprise FIG. 7 which illustrates a flowchart of a method of controlling the tailgate system as a function of whether a tailgate door control command is intended to be an open command or a close command in accordance with one non-limiting aspect of the present invention.



DETAILED DESCRIPTION
FIG. 1 illustrates a vehicle 10 having a split tailgate system 12 embodying one non-limiting aspect of the present invention. The split tailgate system 12 may be an electrically driven system configured to articulate an upper tailgate door 14 and a lower tailgate door 16 between open and closed positions.
FIGS. 2-4b illustrate the automatic movement of one or both of the upper and lower tailgate doors 14, 16 between closed and open positions. As shown, the upper tailgate door 14 may be opened without opening the lower tailgate door 16 (see FIG. 2), both of the upper and lower tailgate doors 14, 16 may be opened at the same time (see FIG. 3), and the lower tailgate door 16 may be opened without opening, or fully opening, the upper tailgate door 14 (see FIGS. 4a-4b).
A controller 18 may be included within the vehicle 10 to control tailgate door opening and closing. The controller may be configured to independently control movements of the upper and lower tailgate doors 14, 16. This may include an upper mode control sequence shown in FIG. 2 where the upper door 14 is actuated to the open position while the lower door 16 remains closed. Another door control sequence may be a dual mode shown in FIG. 3 where both of the upper and lower doors 14, 16 are simultaneously articulating. Depending on the shape of the doors 14, 16, this may include articulating the upper door 14 slightly ahead of the lower door 16. Yet another door control sequence may be a chauffer mode shown in FIGS. 4a-4b where the lower door 16 is actuated while the upper door 14 remains closed.
Wireless messages from a remote control 20, such as but not limited to a fob, may be used to instruct the controller 18 to instigate tailgate door control. Wireline messages from buttons 24, 26, 28, 30, 32 included within a dashboard 34 or a rear of the vehicle 10 may similarly be used to instruct the controller to open and close one or both of the tailgate doors 14, 16. The controller 18 may control operations of an upper electric motor 40 and a lower electric motor 42 in order to respectively control upper and lower tailgate door 14, 16 positioning. While the motors 40, 42 may be positioned anywhere within the vehicle 10, they are shown for exemplary purposes to be disposed within a drain channel 46 around an outer perimeter of the upper tailgate door 14 and within a enclosure of the lower tailgate door 16 that may or may not be watertight.
Because the motors 40, 42 can be controlled to independently articulate the tailgate doors 14, 16, the present invention is able to sequence tailgate door 14, 16 movement in any suitable manner. One of the door control sequences may include limiting occupant exposure to the environment by automatically opening only the lower tailgate door 16. In the past, it was extremely difficult for a user to only open the lower tailgate door 16 since the user was required to partially open the upper tailgate door 14 first. By automatically sequencing movement of the upper and lower tailgate doors 14, 16, the controller 18 is able to automatically open the lower tailgate door 16 in an easier manner and without overly exposing the passenger compartment.
As shown in more detail in FIG. 3, a compartment cover 50 may be included with a storage area 52 to extend rearwardly from a rear seat 54 to the tailgate doors 14, 16. The compartment cover 50 may be positioned above a bottom 56 of the upper tailgate door 14 when closed and below a top 58 of the rear seat 54 in order to separate the storage area 52 into upper and lower storage portions. The coverage of the compartment cover 50 may be adjusted manually by pushing or pulling a leading edge 60, or optionally, with related control of a compartment cover motor 62. When executing door control sequences according to the chauffer mode, the upper tailgate door 14 may maintain a position below a horizontal plane P defined by the compartment cover 50 while the lower tailgate door 16 is being opened in order to limit exposure of the upper storage area and the rest of the passenger compartment to the outside elements.
FIGS. 4a and 4b illustrate a sequence of door movements that maybe coordinated by the controller 18 when opening the lower tailgate door 16 according to the chauffer mode sequence of door controls. As shown in FIG. 2, the bottom portion 56 of the upper tailgate door 14 includes a lock 66 that mates with a latch 68 included on a lip 70 of the lower tailgate door 16. A ledge 72 is positioned below the latch 68 to cover the bottom 56 of the upper tailgate door 14 so that an exterior portion 74 of the upper door 14 is flush with an exterior portion 76 of the lower door 16 when both are closed (see FIG. 1). To open the lower tailgate door 16, the upper tailgate door 14 may be partially opened, at least until the lip 70 is able to articulate past the bottom 56 of the upper tailgate door 14 (see FIG. 4a), and then the lower tailgate door 16 may be articulated to its open position (see FIG. 4b). Depending on the size and shape of the upper and lower tailgate doors 14, 16, an angle of articulation θ of the upper door may be from approximately 10° to approximately 25° or, alternatively, as much as 25% of the total angle θ. Optionally, once the lower tailgate door 16 is clear of the upper tailgate door 14, the upper tailgate door 14 may be automatically articulated back to its closed position or it may remain in the partially open position.
As noted above, the door controls contemplated by the present invention to manage articulation of the upper and lower tailgate doors 14, 16 may be instigated upon receipt of a message sent from the fob 20 or buttons 24, 26, 28, 30, 32 included on the vehicle 10. One of the vehicle buttons 28 may be included on the outside portion 76 of the upper tailgate 14 to control opening and closing of the upper tailgate door 14. Another vehicle button 30 having the same functionality of the button 28 may be included on the bottom side 56 of the upper tailgate door 14 to provide easy button access when the upper tailgate door 14 is open. Another button 32 to control open and closing of the lower tailgate door 16 may be included on the ledge 72 such that it is concealed from view when the upper door 14 is closed, which may be helpful in providing a more uniform rearward appearance for the vehicle 10 than including the button on the exterior portion 74 of the lower tailgate door 16.
With reference to FIG. 1, one of the buttons 24 may be an upper door button included on the dashboard 34 that instructs the controller 18 to open or close the upper tailgate door 14. This button 24 may be ‘fixed’ in that is pre-programmed to control the upper tailgate door 14 at the time of manufacturing. Another button 26 included in the dashboard 34 may be a “programmable” button in that it can be programmed by a vehicle occupant to selectively execute an available door control. For example, a programming selection menu having a number of available door control sequences may be displayed within a display or other human machine interface (HMI) 80 such that user selection of one of the door control sequences controls whether the button 26 controls both doors 14, 16 (dual mode), only the lower door 16 (chauffer mode), or some other operation, such as but not limited to vehicle illumination, e.g., the interior/exterior of the vehicle 10, including the doors 14, 16, may be illuminated. The illumination mode may be “fixed” in vehicles having a single tailgate door or split tailgate doors where the lower tailgate door 16 is powered.
Buttons 84, 86 included on the fob 20 may mimic the functionality provided by the buttons 24, 26 included within the dashboard 34. The fob 20 may include the same “fixed” assignment of an upper door button 84 and the same “programmable” assignment of a programmable button 86. The fob 20 may also include buttons 88, 90, 92 to instruct the controller 18 to execute the vehicle controls, such as but not limited to a door unlock button 90, door lock button 88, and panic button 92, which are commonly employed with remote keyless entry (RKE) related systems. The fob 20 may also perform other operations, such as but not limited to passive entry (PE), including passively supporting tailgate door control sequences. Depression of the fob buttons 84, 86, 88, 90, 92 may instruct the fob 20 to issue a specific message depending on the depressed button. Optionally, the message transmitted from the programmable key 86 may be the same regardless of the operation to be controlled by the controller 18 in response to receipt of the message.
If multiple fobs 20 are authorized to control the vehicle 10, each fob 20 may be configured to issue the same message upon actuation of the same fob button 84, 86, 88, 90, 92. In this manner, the controller 18 need not interpret the messages differently depending on the fob 20 transmitting the message or throughout changes in programming of the programmable button 86. Optionally, while the messages transmitted may be the same for each fob 20, identifiers of the fob 20 transmitting the message may be included. If user specific control is desired, the controller 18 can use the identifiers to lookup an associated user in order to execute user specific operations. In this manner, a first user can program the controller 18 to execute a different tailgate door control sequence than a second user associated with another fob 20 even though both fobs 20 transmit the same message upon actuation of the programmable button 86.
FIG. 5 illustrates a flowchart 100 of a method of controlling the power, split tailgate system 12 in accordance with one non-limiting aspect of the present invention. The method may be executed with the assistance of the controller 18 executing operations for controlling upper and lower tailgate doors 14, 16 according to instructions included within a computer-readable medium. The method may be executed with respect to the system 12 described above or with respect to other systems having arrangements suitable to executing the operations contemplated by the present invention. For exemplary purposes, the method is described with respect to articulating upper and lower tailgate doors 14, 16 about a vehicle body. The present invention, however, is not intended to be limited to any particular direction of articulation or to articulating only upper and lower tailgate doors 14, 16.
Block 102 relates to determining a tailgate door command. The tailgate door command may relate to a command issued to open or close one or more of the upper and/or lower tailgate doors 14, 16. The command may be determined from user interaction with the remote control 20 or a suitable one of the vehicle buttons 24, 26, 28, 30, 32. Block 104 relates to assessing whether the command was triggered by one of the “fixed” buttons 24, 28, 30, 32, 84 or “programmable” buttons 26, 86. For exemplary purposes, the control sequence associated with a fixed button is assumed to be an upper command that indicates a desire to open or close the upper tailgate door 14. Optionally, the described programming may be limited to that completed by a vehicle owner after purchasing the vehicle, as opposed to at the time of manufacturing.
Block 106 is reached if the command is triggered by one of the programmable buttons. Block 106 includes reviewing a memory or other database accessible to the controller 18 to determine the control sequence associated with the actuated button. As noted above, user interaction with the HMI 80 may be used to assign a control sequence to the programmable button 26, 86. The assigned control sequence may be the same for the program button 86 on the fob 20 and the vehicle button 26, or the control sequence may be different for one or the other. In some cases, if different control sequences are assigned to the program button 86 of multiple fobs 20, Block 106 may include interrogating the related message in order to identify the transmitting fob.
Block 110 relates to determining whether the desired control sequence relates to a chauffer mode where only the lower tailgate door 16 is desired to be opened. If chauffer mode is determined in Block 110, an assessment as to whether either one of the upper or lower tailgate doors 14, 16 is currently in the open position is made in Block 112. If either door 14, 16 is open, any open tailgate door 14, 16 is automatically driven to its closed position in Block 114. The assumption to close any open door in response to button actuation is a selectable design 5 parameter. Another assumption could be made to open the lower tailgate door 16 even if the upper tailgate door 14 is open. If neither one of the tailgate doors 14, 16 are open, the lower tailgate door 16 is opened in Block 116.
If the chauffer mode is not determined in Block 110, an assessment is made in Block 118 as to whether the desired control sequence relates to a dual mode where both of the upper and lower tailgate doors 14, 16 are to be simultaneously controlled. If dual mode is determined, an assessment is made in Block 120 as to whether either one of the upper or lower tailgate doors 14, 16 is currently in the open position. If either door 14, 16 is open, any open tailgate door 14, 16 is automatically driven to its closed position in Block 122, and if both doors 14, 16 are closed, both of an upper and lower tailgate doors 14, 16 are opened in Block 124.
Block 126 relates to executing another control when the programmable button has not yet been associated with controlling either one of the upper or lower tailgate doors 14, 16. For exemplary purposes, this other control is shown with respect to vehicle illumination where one or more of the interior or exterior vehicle lights are temporarily illuminated instead of articulating a tailgate door 14, 16. The present invention, however, is not intended to be so limited and fully contemplates executing any other type of control.
Returning to Block 104, if the desired door control is associated with one of the fixed buttons 24, 84, an assessment as to whether either one of the upper or lower tailgate doors 14, 16 is currently in an open position is made in Block 128. If either door is open 14, 16, any open tailgate door 14, 16 is automatically driven to its closed position in Block 130, and if both doors 14, 16 are closed, the upper tailgate door 14 is opened in Block 132. While the fixed button 24, 84 operations executed above are assigned at the time of manufacturing, the present invention fully contemplates reprogramming the fixed buttons 24, 84 in a manner similar to that used with respect to programming the programmable buttons 26, 86. In this way, the present invention may allow a user to assign door control sequences to each of the two door control buttons 84, 86 included on the fob 20 or each of the two door control buttons 24, 26 provided on the dashboard 34.
FIG. 6 illustrates a flowchart 150 of a method of controlling a power, split tailgate 12 in accordance with one non-limiting aspect of the present invention. This method takes into consideration whether an open door was opened manually or electronically before deciding the door control sequence. Block 152 relates to determining a tailgate door command. While the method is described without regard to whether the tailgate door command relates to a programmable or fixed command, such an inquiry can optionally be included in a manner similar to that described above.
Block 154 relates to assessing whether any tailgate door 14, 16 is open if Block 156 determines the tailgate door command to be a control both doors command. If neither door 14, 16 is currently opened, both doors 14, 16 are opened automatically in Block 158. If at least one of the doors 14, 16 is open, Block 160 determines whether the open door 14, 16 was opened manually or electronically. If opened electronically, any open door 14, 16 is closed in Block 162, and if opened manually, an assessment as to whether the both doors 14, 16 were opened manually is made in Block 164. If both doors 14, 16 were opened manually, then both doors 14, 16 are closed in Block 166, and if one door 14, 16 was opened manually, then the unopened door 14, 16 is opened in Block 168.
Block 172 relates to assessing whether any tailgate door 14, 16 is open if Block 170 determines the tailgate door command to be a control lower command. If neither door 14, 16 is currently opened, the lower tailgate door 16 is opened automatically in Block 174. If at least one of the doors 14, 16 is open, Block 176 determines whether the open door 14, 16 was opened manually or electronically. If opened electronically, any open door 14, 16 is closed in Block 178, and if opened manually, an assessment as to whether the upper tailgate door 14 was opened manually is made in Block 180. If the upper tailgate door 14 was not opened manually, then only the lower tailgate door 16 must have been opened manually, resulting in the automatic closing of the lower door 16 in Block 182. If the upper tailgate door 14 was opened manually, then an assessment as to whether the lower tailgate door 16 was also opened manually is made in Block 184. If both doors 14, 16 were opened manually, then both doors 14, 16 are closed in Block 178, and if only the upper door 14 was opened manually, then the lower door 16 is opened in Block 186.
Block 190 relates to assessing whether any tailgate door 14, 16 is open if Block 188 determines the tailgate door command to be a control upper door command. If neither door 14, 16 is currently opened, the upper tailgate door 14 is opened automatically in Block 192. If at least one of the doors 14, 16 is open, Block 194 determines whether the open door 14, 16 was opened manually or electronically. If opened electronically, any open door 14, 16 is closed in Block 196, and if opened manually, an assessment as to whether the lower tailgate door 16 was opened manually is made in Block 198. If the lower tailgate door 16 was not opened manually, then only the upper tailgate door 14 must have been opened manually, resulting in the automatic closing of the upper door 14 in Block 200. If the lower tailgate door 16 was opened manually, then an assessment as to whether the upper tailgate door 14 was also opened manually is made in Block 202. If the both doors 14, 16 were opened manually, then both doors 14, 16 are closed in Block 196, and if only the lower door 16 was opened manually, then the upper door 14 is opened in Block 204.
The first flowchart 100 describes a control method where the tailgate door control commands are executed on the assumption that any open tailgate door 14, 16 should be closed upon receipt of a subsequent door command. The second flowchart 150 described a control method where open tailgated doors 14, 16 are not necessarily closed upon receipt of a subsequent door control command, i.e., the doors 14, 16 may remain open if the open door(s) 14, 16 were opened in a manual operation, such as if a user physically moved the doors 14, 16. The assumptions made in both methods are design parameters and not intended, unless otherwise noted, to limit the scope and contemplation of the present invention. Other assumptions may be made without deviating from the scope and contemplation of the present invention.
For example, FIG. 7 illustrates a flowchart 220 of a method in which decisions to open or close the tailgate doors 14, 16 are made independently of a position of the tailgate doors 14, 16 at the time the door control command is received whether the tailgate doors 14, 16 were opened manually or electronically. Instead, the method assesses the desired door control sequence depending on whether the command was an open or close command. The method begins in Block 222 upon receipt of a tailgate door command message. Block 224 interrogates the door command to determine whether it is an open door command or a close door command. This decision may be based on information included with the door command message or from other information. For example, the fob 20 or vehicle 12 may include separate open and close buttons (not shown) for each of the tailgate doors 14, 16—like the fob 20 lock and unlock buttons 88, 90. Alternatively, an inquiry into the result of the last door control command can also be used to determine whether the current door control command is an open or closed command, i.e., if the last command result indoor 14, 16 opening, then it may be presumed that the next door command would result in door 14, 16 closing and vice versa.
Block 226 interrogates a command of the type intended to open one or more of the doors 14, 16 to determine whether it is an open both command in which both doors 14, 16 are to be opened. If it is an open both command, Block 228 assesses whether any door 14, 16 are currently open such that both doors 14, 16 are automatically opened in Block 230 if no doors are opened and any closed door is opened in Block 232 if at least one door is closed. If the door command was not an open both command, Block 234 interrogates the door command to determine whether it is an open upper command in which only the upper door 14 is to be opened.
If the open upper command is determined, an assessment of whether any door is open is made in Block 236. If no door 14, 16 is open, the upper door 14 is opened in Block 238, else an assessment is made in Block 240 as to whether both doors 14, 16 are open. If both doors are open, the lower door 16 is closed in Block 242, else an assessment is made in Block 244 as to whether the upper door 16 is open. Depending on whether the upper door 14 open, no action is taken in Block 246 or the upper door is opened and the lower door is closed in Block 248.
If the door command was not an open upper command, Block 250 interrogates the door command to determine whether it is an open lower command in which only the lower door 16 is to be opened. If the open lower command is determined, an assessment of whether any door is open is made in Block 252. If no door 14, 16 is open, the lower door 16 is opened in Block 254, else an assessment is made in Block 254 as to whether both doors 14, 16 are open. If both doors are open, the upper door 14 is closed in Block 258, else an assessment is made in Block 260 as to whether the upper door 14 is open. Depending on whether the upper door 14 open, no action is taken in Block 262 or the lower door is opened and the upper door is closed in Block 264.
If the door command was not an open command, and instead, was a close command, Block 268 assess whether the closed command was a close both command in which both of the upper and lower doors 14, 16 are to be closed. If any door is determined to be open in Block 270, the open doors are closed in Block 272, otherwise no action is taken in Block 274. A similar process is repeated in Blocks 276, 278, 280, and 282, as well as in Blocks 284, 286, 288, and 290, where the upper and lower doors 14, 16 are respectively closed if open at the time the corresponding close door command is received. The close door control sequence is described slightly different from the open door control sequence in that the door close operations are instigated with respect to only the commanded door 14, 16, whereas the open door sequence may include commanding a non-commanded door 14, 16.
In more detail, the open sequence may include closing an open door 14, 16 upon receipt of another open command, such as if an open lower command is received when both doors are open. This would require the additional command of closing the upper door 14. In contrast, a similar sequence for a close command would only require closing the lower door 16—the upper door 14 may remain open. The difference between the open and close command sequences are provided to describe the variability in the door control sequences contemplated by the present invention and is done for exemplary purposes, and unless otherwise noted, without intending to limit the scope and contemplation of the present invention.
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale, some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for the claims and/or as a representative basis for teaching one skilled in the art to variously employ the present invention. The features of various implementing embodiments may be combined to form further embodiments of the invention.
While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the scope of the invention.

## Claims

1. A power, split door system for a vehicle, comprising:
a first vehicle door arranged to articulate between a closed position and an open position;
a second vehicle door arranged to articulate between a closed position and an open position;
first and second drive means for moving the first and second doors, respectively, between the closed and open positions; and
a controller for controlling the first and second drive means so as to control movement of the first and second doors between the open and closed positions,
wherein the first and second doors are arranged such that the first door must be at least partially opened to allow opening or closing of the second door, and wherein the controller is arranged to independently control the first and second drive means such that the first and second vehicle doors do not attempt to occupy the same space at the same time.

2. A system as claimed in claim 1, wherein the control means is arranged to independently control the first and second drive means to cause the first vehicle door to at least partially articulate from the closed position toward the open position before the second vehicle door begins to articulate from the closed position to the open position.

3. A system as claimed in claim 1, wherein the controller is arranged to cause the first vehicle door to articulate from the at least partially open position to the closed position after the second vehicle door has articulated towards the open position by a predetermined amount.

4. A system as claimed in claim 1, wherein the drive means comprise at least one electric motor.

5. A system as claimed in claim 4, wherein the motor used to articulate the second vehicle door is positioned within a watertight interior of the second vehicle door.

6. A system as claimed in claim 2, wherein the controller is arranged to cause the first vehicle door to articulate through an angle that is less than or equal to approximately 25% of an angle of articulation required to fully articulate the first vehicle door from the closed position to the open position.

7. A system as claimed in claim 1, wherein the controller is arranged to cause the first vehicle door to articulate between the open and closed positions while the second vehicle door remains in either one of the open and closed positions.

8. A system as claimed in claim 1, wherein the controller is arranged to cause the first and second vehicle doors to be simultaneously articulated between the open and closed positions thereof.

9. A system as claimed in claim 1, wherein the system is a power, split tailgate system for a vehicle having a rear storage area.

10. A system as claimed in claim 9, wherein the first door is an upper tailgate door and the second door is a lower tailgate door.

11. A vehicle comprising a system as claimed in claim 9.

12. A method of articulating a power, split door system of a vehicle, wherein the system includes a first vehicle door arranged to articulate between a closed position and an open position;
a second vehicle door arranged to articulate between a closed position and an open position, the first and second doors being arranged such that the first door must be at least partially opened to allow opening or closing of the second door;
first and second drive means for moving the first and second doors, respectively, between the closed and open positions; and
a controller for controlling the first and second drive means so as to control movement of the first and second doors between the open and closed positions,
the method comprising controlling movement of the first and second doors in sequence such that they do not attempt to occupy the same space at the same time.

13. A method as claimed in claim 12, wherein the system is a power split tailgate system for a vehicle having a rear storage area, and wherein the first door is an upper tailgate door and the second door is a lower tailgate door.

14. A power, split door system for a vehicle, comprising:
a first vehicle door arranged to articulate between a closed position and an open position;
a second vehicle door arranged to articulate between a closed position and an open position;
first and second drive means for moving the first and second doors, respectively, between the closed and open positions; and
a controller for controlling the first and second drive means so as to control movement of the first and second doors between the open and closed positions,
wherein the first and second doors are arranged such that the first door must be at least partially opened to allow opening or closing of the second door, and wherein the controller is arranged to independently control the first and second drive means such that movement of the first and second vehicle doors is sequenced in a suitable manner.

15. A system as claimed in claim 14, wherein the controller is arranged to independently control the first and second drive means to cause the first vehicle door to at least partially articulate from the closed position toward the open position before the second vehicle door begins to articulate from the closed position to the open position.

16. A system as claimed in claim 14, wherein the controller is arranged to cause the first vehicle door to articulate from the at least partially open position to the closed position after the second vehicle door has articulated towards the open position by a predetermined amount.

17. A system as claimed in claim 14, wherein the drive means comprise at least one electric motor.

18. A system as claimed in claim 15, wherein the controller is arranged to cause the first vehicle door to articulate through an angle that is less than or equal to approximately 25% of an angle of articulation required to fully articulate the first vehicle door from the closed position to the open position.

19. A system as claimed in claim 14, wherein the controller is arranged to cause the first vehicle door to articulate between the open and closed positions while the second vehicle door remains in either one of the open and closed positions.

20. A system as claimed in claim 14, wherein the controller is arranged to cause the first and second vehicle doors to be simultaneously articulated between the open and closed positions thereof.