WO2023066766A1

WO2023066766A1 - Releasing a park pawl of a vehicle

Info

Publication number: WO2023066766A1
Application number: PCT/EP2022/078438
Authority: WO
Inventors: Octavian Radulescu
Original assignee: Jaguar Land Rover Limited
Priority date: 2021-10-22
Filing date: 2022-10-12
Publication date: 2023-04-27
Also published as: GB202115176D0; GB2612100A

Abstract

There is provided a control system (300), a vehicle (1), a method (400), and computer software (308), for releasing a park pawl (107) of a vehicle (1) for vehicle service or recovery. The control system comprises one or more controllers (301). The control system is configured to determine (402) that an entry condition for releasing the park pawl is satisfied. The entry condition determination comprises: determining whether an accelerator pedal (114) of the vehicle is depressed for a first time while the vehicle is substantially stationary and while a brake pedal (116) of the vehicle is depressed and while a torque source (102) for outputting torque based on depression of the accelerator pedal is in a non-activated state; and determining whether the accelerator pedal of the vehicle is depressed for a second time while the vehicle is substantially stationary and while the brake pedal is depressed and while the torque source is in the non-activated state.

Description

RELEASING A PARK PAWL OF A VEHICLE

TECHNICAL FIELD

The present disclosure relates to releasing a park pawl of a vehicle. In particular it relates to a user actuation sequence for releasing the park pawl.

BACKGROUND

It is known for vehicles to comprise a park pawl, usually as part of a transmission of the vehicle. The purpose of a park pawl is to lock up the transmission when in an engaged position, to prevent unintended vehicle movement. The park pawl is moved to the engaged position when a gear selector is placed into a ‘P’ position.

Some park pawls are not disengageable via the gear selector if the vehicle is broken down, for instance if the engine will not start. Therefore, some vehicles are fitted with a manual park pawl release mechanism in an engine bay. However, a manual mechanism adds weight and needs to be inaccessible to unauthorised individuals.

Software solutions for moving the park pawl for vehicle service or recovery have been devised. The entry condition for such ‘service modes’ can comprise several steps to prevent unintended activation of the service mode, but the steps can be too complex requiring too much coordination and time. The entry conditions may become specific to individual vehicle models, model years, powertrains or communication buses.

SUMMARY OF THE INVENTION

It is an aim of the present invention to address one or more of the disadvantages associated with the prior art.

Aspects and embodiments of the invention provide a control system, a vehicle, a method, and computer software as claimed in the appended claims.

According to an aspect of the invention there is provided a control system for releasing a park pawl of a vehicle for vehicle service or recovery, the control system comprising one or more controllers, the control system configured to determine that an entry condition for releasing the park pawl is satisfied, the entry condition determination comprising: determining whether an accelerator pedal of the vehicle is depressed for a first time while the vehicle is substantially stationary and while a brake pedal of the vehicle is depressed and while a torque source for outputting torque based on depression of the accelerator pedal is in a non-activated state; and determining whether the accelerator pedal of the vehicle is depressed for a second time while the vehicle is substantially stationary and while the brake pedal is depressed and while the torque source is in the non-activated state.

An advantage is an improved activation sequence. This is because the sequence is fast, is unlikely to be input unintentionally, and uses controls that are used in the widest variety of different vehicle models, model years, powertrains or communication buses.

Optionally, the entry condition determination requires that the depression of the accelerator pedal for the first time and/or for the second time is above a depression threshold.

Optionally, the entry condition determination requires that the brake pedal is continuously depressed between both depressions of the accelerator pedal.

Optionally, the entry condition determination requires that depression of the accelerator pedal between the first time and the second time is below the depression threshold.

Optionally, the entry condition determination requires that the depression of the accelerator pedal for the second time is performed for at least a threshold duration.

Optionally, determining that the brake pedal is depressed requires an indication that the brake pedal of the vehicle is depressed above a threshold and/or requires an indication that brake pressure is above a threshold.

Optionally, the entry condition determination requires an indication that an electric charging port of the vehicle is not connected to a charging cable.

Optionally, the control system is configured to, in dependence on satisfaction of the entry condition, request operation of at least one actuator to enable release of the park pawl. Optionally, the requested operation is enabled even if a gear selector selection is a Park selection.

Optionally, the actuator comprises a fluid pump.

Optionally, the requested operation comprises operation of an electric motor (108).

Optionally, the control system is configured to, in dependence on satisfaction of the entry condition, enable the torque source, the torque source being an internal combustion engine, to be cranked to provide energy for the operation of the actuator.

Optionally, if the cranking successfully starts the internal combustion engine, the control system is configured to not request the operation of the actuator to release the park pawl, and instead to enable release of the park pawl via user-initiated gear selection.

Optionally, the control system is configured to, in dependence on satisfaction of the entry condition, cause rendering of user feedback prompting the user to provide one or more user inputs to enable release of the park pawl.

Optionally, the one or more user inputs comprise a first user input for causing engine cranking, and a second user input comprising brake pedal depression.

Optionally, causing release of the park pawl requires the first user input and the second user input to be performed concurrently.

Optionally, the control system is configured to determine a gear selector selection, and if the gear selector selection is a Park selection, cause rendering of transmission state feedback to the user when the park pawl is released to indicate that a transmission of the vehicle is not in a Park state.

According to another aspect of the invention there is provided a vehicle comprising the control system. According to a further aspect of the invention there is provided a method of releasing a park pawl of a vehicle for vehicle service or recovery, the method comprising determining that an entry condition for releasing the park pawl is satisfied, the entry condition determination comprising: determining whether an accelerator pedal of the vehicle is depressed for a first time while the vehicle is substantially stationary and while a brake pedal of the vehicle is depressed and while a torque source for outputting torque based on depression of the accelerator pedal is in a non-activated state; and determining whether the accelerator pedal of the vehicle is depressed for a second time while the vehicle is substantially stationary and while the brake pedal is depressed and while the torque source is in the non-activated state.

According to a further aspect of the invention there is provided computer software that, when executed, is arranged to perform any one or more of the methods described herein. According to a further aspect of the invention there is provided a non-transitory computer readable medium comprising computer readable instructions that, when executed by a processor, cause performance of any one or more of the methods described herein.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination that falls within the scope of the appended claims. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination that falls within the scope of the appended claims, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 illustrates an example of a vehicle;

FIG. 2 illustrates an example of a system; FIGS. 3A, 3B illustrate an example of a control system and of a non-transitory computer- readable storage medium respectively;

FIG. 4 illustrates an example of a method; and

FIG. 5 illustrates an example timing diagram.

DETAILED DESCRIPTION

FIG. 1 illustrates an example of a vehicle 1 in which embodiments of the invention can be implemented. In some, but not necessarily all examples, the vehicle 1 is a passenger vehicle, also referred to as a passenger car or as an automobile. In other examples, embodiments of the invention can be implemented for other applications, such as commercial vehicles.

FIG. 2 illustrates an example system 2 for the vehicle 1 .

The system 2 comprises a torque source 102 for outputting drive torque for driving road wheels of the vehicle 1. In the illustrated example, the torque source 102 comprises an internal combustion engine 102 (‘engine’). In some implementations, the vehicle 1 is a hybrid electric vehicle comprising the engine 102 and an electric machine such as an electric drive unit. In other examples, the torque source 102 is a different type of torque source.

The system 2 comprises an optional transmission 104 operably coupled to the torque source 102. The transmission 104 comprises a geartrain for providing a gear reduction between the torque source 102 and road wheels of the vehicle 1. In at least some examples, the transmission 104 is an automatic transmission or a semi-automatic transmission.

The system 2 comprises a park pawl mechanism for locking up the transmission 104, drivetrain and/or powertrain. The park pawl mechanism comprises a park pawl actuator 106 and the park pawl 107. The park pawl 107 is actuatable between an interference position (engaged position) that locks up the transmission 104 and a non-interference position (nonengaged position) that does not lock up the transmission 104.

In some examples, the park pawl actuator 106 comprises a hydraulic park pawl actuator. The hydraulic park pawl actuator 106 may be controllable by a control system 300 based on a gear selector selection of the illustrated gear selector 110. The hydraulic park pawl actuator 106 may be actuated by transmission fluid. The transmission fluid may first need to be pressurised by an actuator 108 such as a fluid pump. The fluid pump 108 may comprise a transmission fluid pump.

In a first, hydraulic implementation, the engine 102 is configured to provide energy for the operation of the fluid pump 108. For example, the fluid pump 108 may be coupled to an output shaft from the engine 102 via gears and/or a belt and/or a chain.

In a second, electro-hydraulic implementation, the fluid pump 108 comprises an electric motor so that the transmission fluid can be pressurised without requiring cranking or running of the engine 102. For example, an electric motor may be coupled to a pump unit via any appropriate drive such as a planetary drive.

In other examples, the park pawl could be actuated via a different means than hydraulic or electro-hydraulic actuation. In examples, the different means comprises an electric park pawl (electric motor for the park pawl), wherein no pressure is required to lift/engage the park pawl.

The gear selector 110 can be any appropriate type, not necessarily limited to the illustrated lever. In some examples, the gear selector 110 is a ‘shift-by-wire’ gear selector 110 that is not mechanically coupled to the transmission 104. The gear selector 110 is any appropriate human-machine interface(s) that enable at least the following user selections:

- a Park (‘P’) selection for causing the park pawl 107 to be in the engaged position and causing the geartrain to be in neutral and in some cases causing an electronic parking brake to be automatically applied;

- a Neutral (‘N’) selection for causing the park pawl 107 to be in the non-engaged position and causing the geartrain to be in neutral and in some cases causing the electronic parking brake to be released; and

- one or more Drive (‘D’)/Reverse (‘R’) selections for causing the park pawl 107 to be in the non-engaged position and causing the geartrain to be in-gear for driving the vehicle 1 and in some cases causing the electronic parking brake to be released.

In some implementations, if the gear selector 110 is set to a ‘P’ (Park) selection, the park pawl 107 may be temporarily actuatable away from the engaged position for vehicle service or recovery, however, continuous energy may need to be supplied or the park pawl 107 will drop back into the engaged position. For example, a magnetic holding mechanism (not shown) can hold the park pawl 107 in the non-engaged position for some time but constant electrical power may be needed from an electrical energy source such as a battery. To keep the park pawl 107 lifted, the gear selector 110 would normally need to stay in Neutral (‘N’). In examples, when the herein described activation sequence causes the park pawl 107 to be temporarily actuated away from the engaged position, the park selector 110 may no longer show Park (‘P’) in the usual manner. This feeds back to the driver that the vehicle 1 is no longer in a secured state.

In other implementations, the park pawl 107 can be actuated away from the engaged position for vehicle service or recovery in a persistent manner that does not require continuous energy supply.

The system 2 further comprises an output device 112 or an input/output device controllable to render information to the user. In some examples, the output device 112 comprises a display or a touchscreen display. In some examples, the output device 112 is located at a dashboard of the vehicle 1. Additionally, or alternatively, an output device 112 can comprise a loudspeaker or any other appropriate rendering device.

The system 2 further comprises an accelerator pedal 114. The accelerator pedal 114 may be a foot pedal. The accelerator pedal 114 can be depressed to control output torque from the torque source 102, if the torque source is in an activated state.

The system 2 further comprises a brake pedal 116. The brake pedal 116 may be another foot pedal. The brake pedal 116 can be depressed to control friction braking, such as engagement of brake pads with brake rotors. The brake pedal 116 may be coupled to a hydraulic brake system.

The system 2 further comprises an engine start user control 118 for transitioning the torque source 102 between its non-activated state and its activated state. For example, the engine start user control 118 can comprise a ‘Start’ button or a key barrel or any other appropriate engine start user control 118. An activated state of the torque source 102 is a state in which the torque source 102 is able to produce output torque for driving the vehicle 1 in response to accelerator pedal depression. In some examples, normal activation of the torque source 102 may further require concurrent pressing of the brake pedal 116 when the engine start user control 118 is actuated, otherwise the vehicle 1 may only enter or stay in an ‘ignition ON’ state without activating the torque source 102. The system 2 further includes a control system 300 operably coupled to various ones of the elements described above. The control system 300 may be configured, among other things, to release the park pawl 107 of the transmission 104 for vehicle service or recovery. In an implementation, the control system 300 comprises a Transmission Control Module (TCM) or a Vehicle Supervisory Controller (VSC) module.

As shown in FIG. 3A, the control system 300 can comprise at least one controller 301. The controller 301 of FIG. 3A includes at least one processor 304; and at least one memory device 306 electrically coupled to the electronic processor 304 and having instructions 308 (e.g. a computer program) stored therein, the at least one memory device 306 and the instructions 308 configured to, with the at least one processor 304, cause any one or more of the methods described herein to be performed. The processor 304 may have an interface 302 such as an electrical input/output I/O or electrical input for receiving information and interacting with external components. FIG. 3B illustrates a non-transitory computer-readable storage medium 330 comprising the instructions 308 (computer software).

FIGS. 4 and 5 illustrate a method 400 and a timing diagram, respectively, setting out how the invention could be implemented in various examples. The method 400 may be implemented by the control system 300 described above.

The method 400 is for releasing the park pawl 107 of the vehicle 1 for vehicle service or recovery, for example for enabling the vehicle 1 to be loaded onto a tow truck or moved a short distance. This can be referred to as a ‘Service Mode’ of the control system 300, such as a ‘Service Mode’ of the control system 300. In an example use case, the park pawl 107 cannot be moved to the non-engaged position because the torque source 102 has failed to start or because some other feature for enabling lifting the park pawl 107 is inoperative.

The method 400 starts at operation 402, comprising determining that an entry condition for releasing the park pawl 107 is satisfied. At operation 404, the Service Mode has been entered and the user is prompted to provide further ‘confirmatory’ user inputs to initiate pawl release. At operation 406, the further user inputs are received. At operation 408, release of the park pawl 107 is requested. The timing diagram of FIG. 5 comprises several graphs illustrating, at times t1-t4, steps for satisfying the entry condition. Times t5-t6 illustrate the prompts and the further ‘confirmatory’ inputs and the pawl release.

Graph 502 refers to a ‘power mode’ of the torque source 102, i.e., whether the torque source 102 is in its non-activated state (‘0’) or in a state (‘1) able to provide energy for the fluid pump 108. If the torque source 102 is an engine 102, the engine 102 may be able to provide energy for the fluid pump 108 while the engine 102 is being cranked by a starter motor or other electric machine, even if the engine 102 cannot or will not start (fire).

In examples in which the torque source 102 does not need to be cranked to provide energy for releasing the park pawl 107, torque source activation/cranking may be omitted.

Graphs 504 and 506 refer to a brake pedal status and an accelerator pedal status, respectively, indicating whether said pedal is not depressed (‘0’) or depressed (T).

Graphs 508 and 510 refer to messages rendered to the user operating the pedals, wherein ‘0’ means they are not rendered and T means they are rendered.

Graph 512 refers to the status of the park pawl 107, indicating whether the park pawl 107 is in the engaged position (T) or in the non-engaged position (‘0’).

The operations of FIG. 4 are now referred to in more detail, with reference to FIG. 5.

Operation 402 comprises determining that the entry condition is satisfied. The requirements are set out below. In summary, the requirements comprise double-actuation of the accelerator pedal 114 while the brake pedal 116 is held to secure the vehicle 1 in a stationary condition, and while the torque source 102 is in the non-activated state.

As shown in graph 504 of FIG. 5 at time t1 , the entry condition requires that the brake pedal 116 is depressed. In some examples, the brake pedal 116 is treated as ‘depressed’ when its position is beyond a threshold brake pedal position, and/or when brake fluid pressure is above a threshold pressure. The thresholds described above may depend on calibration. For example, the threshold pressure can be a value greater than 5bar or greater than 10bar or equivalent units. The threshold brake pedal position can be a value greater than or equal to 5% of its travel range. A reasonably low value of the threshold (e.g., <40% max pressure/travel) is comfortable for the user in examples where the brake pedal 116 needs to be held for a long time.

As shown in graph 506 of FIG. 5 at times t2-t4, the entry condition requires the accelerator pedal 114 to be depressed twice in sequence, while the brake pedal 116 is required to be continuously depressed. In some examples, the accelerator pedal 114 is treated as ‘depressed’ when its position is beyond a depression threshold.

The depression threshold of the accelerator pedal 114 can depend on calibration. For example, the depression threshold can comprise a kickdown threshold or another similar value close to 100% depression, such as a value greater than 70% or greater than 80% or greater than 90%. The depression threshold is set high so that accidental actuation is less likely.

Time t2 shows the first depression of the accelerator pedal 114, time t3 shows release of the accelerator pedal 114, and time t4 shows the second depression of the accelerator pedal 114 for the second time. If the brake pedal 116 is released at any point during times t2, t3 and t4, the entry condition is not satisfied and the user may have to start the pedal sequence again. The double-actuation requirement ensures that the Service Mode is unlikely to be activated unintentionally.

The release of the accelerator pedal 114 at time t3 may require the accelerator pedal 114 to be fully released so that its position is substantially at 0%, or may merely require the accelerator pedal 114 to be partially released so that its position falls below a threshold equal to or lower than the depression threshold.

In some examples, the entry condition requires the depression of the accelerator pedal 114 for the second time to be performed for at least a threshold duration. For example, the depression may need to be above the depression threshold continuously for at least this minimum threshold duration. The threshold duration can be in the order of seconds and less than ten seconds. The threshold duration can be less than five seconds, for example. The threshold duration can be longer than, for example, 1.5 seconds, to reduce the chance of unintended activation of Service Mode. The rationale for a threshold duration for the second depression of the accelerator pedal 114 is that this is the last action for initiating Service Mode, therefore as soon as the threshold duration has elapsed a confirmatory message may be rendered to the user to confirm that Service Mode has been entered. This feedback gives the user confidence that they can now release the accelerator pedal 114.

By extension, the first depression of the accelerator pedal 114 may have no minimum threshold duration because there is no feedback to confirm when the user can release the accelerator pedal 114. Likewise, there may be no minimum threshold duration for which the accelerator pedal 114 is to be released between the first and second actuations. Alternatively, instead of no threshold duration, a relatively short threshold duration could be implemented (no longer than 1 second).

The entry condition also comprises further requirements to be continuously satisfied at least during the pedal sequence or thereafter.

The entry condition requires that the vehicle 1 is substantially stationary and remains stationary for the duration of the pedal sequence. This can be verified by detecting wheel speed and/or shaft speed in a drivetrain.

The entry condition requires that the torque source 102 is in the non-activated state for the duration of the pedal sequence. The entry condition can require that the speed of the torque source(s) is substantially zero.

If the vehicle 1 is a hybrid electric or all-electric vehicle, the entry condition can require an indication that an electric charging port 117 of the vehicle 1 is not connected to a charging cable. This ensures that if the vehicle 1 moves unintentionally after the park pawl 107 is lifted, the charging cable is not dragged.

The entry condition determination can require an indication that the vehicle 1 is not positioned on an excessive incline, in case the vehicle 1 moves unintentionally after the park pawl 107 is lifted. An inertial measurement sensor/accelerometer can provide this indication. The entry condition determination can require an indication that transmission fluid temperature is not outside a threshold or range. A temperature sensor can provide this indication. If the temperature is too cold or too hot, the fluid pump 108 and/or park pawl mechanism may be inoperable.

At least some of the above further requirements can be implemented as exit conditions for exiting Service Mode, if they cease to be satisfied at any time while Service Mode is active. Therefore, in effect, at least some of the above further requirements must be satisfied continuously during Service Mode.

At operation 404, the Service Mode is now active due to satisfaction of the entry condition.

In response to satisfaction of the entry condition and the Service Mode being entered, operation 404 comprises causing rendering of user feedback, for example via the output device 112. The user feedback may inform the user that the pedal sequence was performed successfully. As shown by graph 508 of FIG. 5 at time t5, the user feedback may be rendered in response to the threshold duration being reached, so the user knows to release their foot from the accelerator pedal 114.

In some examples, entering the Service Mode is necessary but not sufficient to cause release of the park pawl 107. The user feedback may prompt the user to provide one or more further user inputs to enable release of the park pawl 107. The further user inputs act as a further confirmation of intention, and ensure that the vehicle 1 is held on the friction brakes when the park pawl 107 is released.

In some, but not necessarily all examples, the further user inputs comprise a first user input (graph 502) for causing engine cranking (if the fluid pump 108 is engine-driven), and a second user input (graph 504) comprising brake pedal depression for securing the vehicle 1 in the stationary position. The first user input can comprise user actuation of the engine start user control 118 of FIG. 2. The brake pedal depression may comprise a threshold similar to that described in relation to operation 402.

The prompt can comprise the message “Gearbox in service mode. Press Start button while pressing the brake pedal 116 to release from Park” or similar. Therefore, the user does not need to refer to an owner’s manual or technician’s manual and is instructed on specifically what they need to do. This is useful for example if the vehicle 1 needs to be moved quickly.

If the energy for the park pawl is from an electric motor, engine cranking may not be required so the first user input may instead comprise selecting Neutral (‘N’) while pressing the brake pedal 116.

The method 400 may require both the first and second user inputs to be performed concurrently. If the user releases the brake pedal 116 before engine cranking or before the park pawl 107 has been released, Service Mode may exit. This continuous braking requirement ensures vehicle rollaway is prevented and ensures that the rest of the method 400 is performed by the same user in the driver’s seat. In some examples, the brake pedal 116 must be depressed continuously from time t1 to t6.

Operation 406 of the method 400 of FIG. 4 comprises receiving the first and second user inputs as described above. In response, operation 408 comprises requesting operation of the fluid pump 108 and the park pawl actuator 106 during engine cranking. This corresponds to time t6 in FIG. 5.

The method 400 may crank the engine 102 (graph 502) for as long as the engine start user control 118 is pressed, to build up fluid pressure, operate the fluid pump 108, and then cause the park pawl actuator 106 to automatically move the park pawl 107 to the non-engaged position (graph 512) even if the gear selector 110 has Park (‘P’) selected. In this use case, the engine 102 may not start (fire) because it is assumed that the engine 102 cannot start due to an underlying fault.

However, if the engine 102 does start and is able to run, the method 400 may abort Service Mode and return to normal shift-by-wire operation. That is, the method 400 may ensure that the park pawl 107 is at whatever position is required by the gear selector 110. For instance, if Park (‘P’) is selected, the park pawl 107 may be left in the engaged position or moved back to the engaged position. With the engine 102 running, the user may be able to engage any of Park, Neutral, Drive, and Reverse. By contrast, in the Service Mode, Park and Neutral are available but not Drive or Reverse. After the park pawl 107 has been moved to the non-engaged position, the method 400 may enable the brake pedal 116 to be released.

The method 400 up to this point has not required the user to move the gear selector 110 from whatever position it was in before time t1. However, during engine cranking or once the park pawl 107 has been lifted, the user may be free to select Neutral (‘N’) to disengage the electronic parking brake to enable the vehicle 1 to be transported, despite the fact that the torque source 102 is not running. This distinguishes from normal operation in which the gear selector 110 is limited to Park (‘P’) if the torque source 102 is not running.

If the user is still depressing the accelerator pedal 114 at the time of engine cranking, they may be prompted to release the accelerator pedal 114, for instance if an engine start inhibit function would normally prevent engine start due to accelerator pedal depression during cranking. Alternatively, the user’s depression of the accelerator pedal 114 may be ignored.

Graph 510 of FIG. 5 comprises, at time t6, rendering transmission state feedback to the user when the park pawl 107 has been released or is about to be released, if Park (‘P’) is selected, to indicate that the vehicle 1 is not in a Park state. This mismatch between gear selector position and transmission position can occur because the gear selector 110 is shift-by-wire. For instance, the output device 112 may render the transmission state feedback message “Gearbox not in Park”. This informs the user to not infer the state of the park pawl 107 based on the gear selector 110 despite Park (‘P’) being selected. The gear selector 110 may still indicate Park (‘P’) despite the park pawl 107 no longer being in the engaged position.

Additionally, or alternatively, output devices integral with the gear selector 110, such as a set of lights, may be operated differently than normal to provide this transmission state feedback. For instance, an ‘N’ light or ‘P’ light may flash (instead of solid illumination) to indicate that the transmission 104 is not in a Park state despite Park (‘P’) being initially selected. This could occur concurrently to rendering the message.

If Neutral (‘N’) is selected, the transmission state feedback may stop being rendered.

The Service Mode/method 400 may remain active for a period of time, to hold the park pawl 107 at the non-engaged position for vehicle service or recovery. Various example exit conditions for exiting the Service Mode are described below. If the user selects Park (‘P’), the method 400 may move the park pawl 107 to the engaged position and exit Service Mode, returning to normal shift-by-wire operation. The transmission state feedback may stop being rendered.

If the engine 102 is able to run, the method 400 may exit Service Mode and go back to normal shift-by-wire operation. The “Gearbox not in Park” message may continue to be rendered until any gear range is selected.

If the vehicle 1 is shut down to a low energy state power mode, the method 400 may exit Service Mode.

In some examples, Service Mode is exited if a calibratable time limit expires such as 10 minutes or some other value between 3 minutes and 30 minutes. This moves the park pawl 107 automatically back to the engaged position once the period of time has elapsed, provided that the vehicle 1 is substantially stationary (e.g., <0.5kph).

For purposes of this disclosure, it is to be understood that the controller(s) described herein can each comprise a control unit or computational device having one or more electronic processors. A vehicle 1 and/or a system thereof may comprise a single control unit or electronic controller or alternatively different functions of the controller(s) may be embodied in, or hosted in, different control units or controllers. A set of instructions could be provided which, when executed, cause said controller(s) or control unit(s) to implement the control techniques described herein (including the described method(s)). The set of instructions may be embedded in one or more electronic processors, or alternatively, the set of instructions could be provided as software to be executed by one or more electronic processor(s). For example, a first controller may be implemented in software run on one or more electronic processors, and one or more other controllers may also be implemented in software run on one or more electronic processors, optionally the same one or more processors as the first controller. It will be appreciated, however, that other arrangements are also useful, and therefore, the present disclosure is not intended to be limited to any particular arrangement. In any event, the set of instructions described above may be embedded in a computer- readable storage medium (e.g., a non-transitory computer-readable storage medium) that may comprise any mechanism for storing information in a form readable by a machine or electronic processors/computational device, including, without limitation: a magnetic storage medium (e.g., floppy diskette); optical storage medium (e.g., CD-ROM); magneto optical storage medium; read only memory (ROM); random access memory (RAM); erasable programmable memory (e.g., EPROM and EEPROM); flash memory; or electrical or other types of medium for storing such information/instructions.

It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

The blocks illustrated in FIGS. 4 and 5 may represent steps in a method and/or sections of code in the computer program 308. The illustration of a particular order to the blocks does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block may be varied. Furthermore, it may be possible for some steps to be omitted.

Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed.

Features described in the preceding description may be used in combinations other than the combinations explicitly described.

Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

1. A control system for releasing a park pawl of a vehicle for vehicle service or recovery, the control system comprising one or more controllers, the control system configured to determine that an entry condition for releasing the park pawl is satisfied, the entry condition determination comprising: determining whether an accelerator pedal of the vehicle is depressed for a first time while the vehicle is substantially stationary and while a brake pedal of the vehicle is depressed and while a torque source for outputting torque based on depression of the accelerator pedal is in a non-activated state; and determining whether the accelerator pedal of the vehicle is depressed for a second time while the vehicle is substantially stationary and while the brake pedal is depressed and while the torque source is in the non-activated state.

2. The control system of claim 1 , wherein the entry condition determination requires that the depression of the accelerator pedal for the first time and/or for the second time is above a depression threshold.

3. The control system of claim 1 or 2, wherein the entry condition determination requires that the brake pedal is continuously depressed between both depressions of the accelerator pedal.

4. The control system of claim 1 , 2 or 3, wherein the entry condition determination requires that depression of the accelerator pedal between the first time and the second time is below the depression threshold.

5. The control system of any preceding claim, wherein the entry condition determination requires that the depression of the accelerator pedal for the second time is performed for at least a threshold duration.

6. The control system of any preceding claim, wherein determining that the brake pedal is depressed requires an indication that the brake pedal of the vehicle is depressed above a threshold and/or requires an indication that brake pressure is above a threshold.

7. The control system of any preceding claim, wherein the entry condition determination requires an indication that an electric charging port of the vehicle is not connected to a charging cable.

8. The control system of any preceding claim configured to, in dependence on satisfaction of the entry condition, request operation of at least one actuator to enable release of the park pawl.

9. The control system of claim 8, wherein the requested operation is enabled even if a gear selector selection is a Park selection.

10. The control system of claim 8 or 9, wherein the actuator comprises a fluid pump.

11. The control system of claim 8, 9 or 10, wherein the requested operation comprises operation of an electric motor.

12. The control system of claim 8, 9 or 10 configured to, in dependence on satisfaction of the entry condition, enable the torque source, the torque source being an internal combustion engine, to be cranked to provide energy for the operation of the actuator.

13. The control system of claim 12, wherein if the cranking successfully starts the internal combustion engine, the control system is configured to not request the operation of the actuator to release the park pawl, and instead to enable release of the park pawl via user- initiated gear selection.

14. The control system of any preceding claim configured to, in dependence on satisfaction of the entry condition, cause rendering of user feedback prompting the user to provide one or more user inputs to enable release of the park pawl.

15. The control system of claim 14, wherein the one or more user inputs comprise a first user input for causing engine cranking, and a second user input comprising brake pedal depression.

16. The control system of claim 15, wherein causing release of the park pawl requires the first user input and the second user input to be performed concurrently.

17. The control system of any preceding claim configured to determine a gear selector selection, and if the gear selector selection is a Park selection, cause rendering of transmission state feedback to the user when the park pawl is released to indicate that a transmission of the vehicle is not in a Park state.

18. A transmission comprising a park pawl and a control system as claimed in any preceding claim.

19. A powertrain comprising a park pawl and a control system as claimed in any one of claims 1 to 17.

20. A vehicle comprising: the control system of any one of claims 1 to 17; a transmission as claimed in claim 18; or a powertrain as claimed in claim 19.

21 . A method of releasing a park pawl of a vehicle for vehicle service or recovery, the method comprising determining that an entry condition for releasing the park pawl is satisfied, the entry condition determination comprising: determining whether an accelerator pedal of the vehicle is depressed for a first time while the vehicle is substantially stationary and while a brake pedal of the vehicle is depressed and while a torque source for outputting torque based on depression of the accelerator pedal is in a non-activated state; and determining whether the accelerator pedal of the vehicle is depressed for a second time while the vehicle is substantially stationary and while the brake pedal is depressed and while the torque source is in the non-activated state.

22. Computer software that, when executed, is arranged to perform a method according to claim 21.

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