A control device for controlling a vehicle engine

Abstract

A control device for controlling an engine of a vehicle, the control device comprising a control device configured to: to switch off the engine's power generation while the vehicle is moving, depending on whether at least one criterion is met; initiate a restart of power generation by the engine in response to at least one input signal indicating a need for the engine to restart in order to provide a required power output; to receive a target engine speed value as a function of a current drive shaft speed; to cause the motor to maintain a speed no greater than a target motor speed during a period after receipt of the at least one input signal and until a further signal is received indicating that reconnection of the motor to a drive shaft has occurred, the target motor speed being dependent on the target motor speed value; and after receiving the further signal, to allow the engine to exceed the target engine speed, wherein the controller is configured to determine a target engine speed dependent on the idle speed of the engine depending on whether the drive shaft speed is at or below a threshold.

Description

FIELD OF TECHNOLOGY

[0001] The present disclosure relates to a control device for controlling an engine of a vehicle. In particular, but not exclusively, it relates to a control device for controlling an engine of a passenger car.

[0002] Aspects of the invention relate to a control device, a control system, a vehicle and a method. STATE OF THE ART

[0003] To improve fuel economy and reduce emissions, vehicles have recently been equipped with systems that open the powertrain and shut down the engine while the vehicle is moving when the driver has either no or very light throttle requests. When the driver requests an engine restart by pressing the accelerator pedal, or when a system-induced restart occurs (for example, in response to a request to restart the engine for battery charging or HVAC (heating, ventilation, and air conditioning)), the transmission will sometimes not engage because slippage across the engage clutch becomes too great. This can occur when a second torque request is received from the engine control system while the transmission is attempting to close the clutch, or because engine speed increases too rapidly for the transmission to reach the running clutch and fully engage.The state of the art are: DE 102 21 701 A1, GB 2 492 066 A, DE 10 2005 049 842 A1, DE 10 2013 208 201 A1, DE 10 2011 079 079 A1, DE 10 2012 209 067 A1.

[0004] The present invention aims to solve this problem of non-engagement of the transmission. SUMMARY OF THE INVENTION

[0005] Aspects and embodiments of the invention provide a control device, a control system, a vehicle and a method according to the appended claims.

[0006] According to one aspect of the invention, a control device for controlling an engine of a vehicle is provided, the control device comprising a controller configured to cause the power generation of the engine to be switched off during movement of the vehicle in dependence on at least one criterion being met; to cause the power generation by the engine to be restarted in dependence on at least one input signal indicating a need to restart the engine to provide a required power output; to receive a desired engine speed value in dependence on a current drive shaft speed;causes the motor to maintain a speed no greater than a desired motor speed for a period after receiving the at least one input signal and indicates that reconnection of the motor to a drive shaft has been established until receiving a further signal, the desired motor speed being dependent on the desired motor speed value; and allows the motor speed to exceed the desired motor speed after receiving the further signal;

[0007] This offers the advantage of keeping the engine speed sufficiently low to prevent a degree of clutch slippage that could otherwise result in the transmission not being engaged. Furthermore, if the input signal is provided by a system control device, such as a battery charging system or a heating system, it allows the engine to be reconnected without subjecting the vehicle's occupants to an unpleasant sudden increase in acceleration.

[0008] It should be noted that the target engine speed value depends on the current drive shaft speed, but the target engine speed value does not have to be determined from the current drive shaft speed. For example, the current drive shaft speed can be determined indirectly from another speed, such as the wheel speed measured by an ABS (anti-lock braking system).

[0009] In some embodiments, the target engine speed is independent of the required power indicated by the at least one input signal. This provides the advantage that, even if the input signal(s) request power that requires the engine to run at a relatively high speed, the target engine speed is not affected by the required amount of power.

[0010] In some embodiments, the target engine speed value depends on the current drive shaft speed and the ratio of a gear to be engaged.

[0011] In some embodiments, the controller is configured to determine the target engine speed from the target engine speed value and the ratio of a gear to be engaged.

[0012] In some embodiments, an expected engine speed may be derived from the gear ratio of the gear to be engaged and a vehicle speed or the current drive shaft speed; and the target engine speed is arranged to be within a predefined difference from the expected engine speed. The predefined difference may comprise a difference between 0 and 60 revolutions per minute.

[0013] In some embodiments, the controller is configured to continuously receive signals from a transmission control module, the signals including a desired engine speed value dependent on a current drive shaft speed, the transmission control module being configured to cause the engine to reconnect to the drive shaft when the engine speed is at or below the desired engine speed.

[0014] In some embodiments, the controller is configured to determine a target engine speed dependent on the engine idle speed, depending on the drive shaft speed being at or below a threshold. The target engine speed may be within a predefined range of the engine idle speed.

[0015] In some embodiments, the controller is configured to increase the engine speed above the target engine speed and decrease to the target engine speed before reconnecting the drive shaft to the engine. This provides the advantage of allowing the engine speed to be increased to the target engine speed more quickly.

[0016] In some embodiments, the at least one input signal indicating a need to restart the engine to provide a required power output comprises an input signal generated in response to a user input.

[0017] In some embodiments, the at least one input signal indicating a need to restart the engine to provide a required power output includes an input signal indicating that a brake pressure has been reduced below a threshold.

[0018] In some embodiments, the at least one input signal indicating a need to restart the engine to provide a required power output includes an input signal indicating a user request to accelerate the vehicle.

[0019] In some embodiments, the at least one input signal indicating a need to restart the engine to provide a required power output includes an input signal indicating a user request for a gear change.

[0020] In some embodiments, the controller is configured to restart power generation by the motor and increase the motor speed at a rate dependent on the at least one input signal before reconnecting the motor to the drive shaft. This provides the advantage of allowing the motor speed to be increased to the target engine speed more quickly, if needed.

[0021] In some embodiments, the at least one input indicating a need to restart power generation by the engine includes a request for power from a system of the vehicle that requires power to perform a function. The function may include at least one of the following group: battery charging; heating; ventilation; and air conditioning.

[0022] In some embodiments, the at least one criterion comprises at least one of the vehicle speed falling below a first threshold and a brake pressure exceeding a second threshold.

[0023] According to a further aspect of the invention, a control device is provided, comprising: an electronic processor having an electrical input for receiving at least one input signal and another signal; and an electronic storage device electrically coupled to the electronic processor and containing instructions stored therein, the instructions configured to cause the electronic processor to cause the shutdown of power generation by the engine during movement of the vehicle in response to at least one criterion being met; to cause power generation by the engine to be restarted in response to at least one input signal indicating a need to restart the engine to provide a required power output; to receive a desired engine speed value in response to a current drive shaft speed;causing the motor to maintain a speed no greater than a desired motor speed for a period after receiving the at least one input signal and until a further signal is received indicating that reconnection of the motor to a drive shaft has been established, wherein the desired motor speed is dependent on the desired motor speed value; and allowing the motor speed to exceed the desired motor speed after receiving the further signal;

[0024] According to a further aspect of the invention, a control system is provided for controlling an engine of a vehicle and for controlling the connection and disconnection of the engine to / from a drive shaft, wherein the control system is configured to enable the disconnection of the engine from the drive shaft and the shutdown of the engine's power generation during movement of the vehicle; and responsive to at least one input indicating a need to restart the engine to provide a required power output, to cause the engine's power generation to restart and the engine's power generation to reconnect to the drive shaft, wherein the control system is configured to limit the engine speed so that it does not exceed a desired engine speed when the engine is reconnected to the drive shaft, and wherein the desired engine speed is dependent on a current drive shaft speed.

[0025] This offers the advantage of keeping the engine speed sufficiently low to prevent a degree of clutch slippage that could otherwise cause the transmission to fail to engage. Furthermore, if the input signal is provided by a system control device, such as a battery charging system or a heating system, it allows the engine to be reconnected without subjecting the vehicle's occupants to an unpleasant sudden increase in acceleration.

[0026] In some embodiments, the desired engine speed is independent of the input indicating the required power output.

[0027] In some embodiments, the target engine speed depends on the current drive shaft speed and the ratio of a gear to be engaged.

[0028] In some embodiments, the control system is configured to determine the desired engine speed as a function of the engine idle speed in response to the drive shaft speed being at or below a threshold.

[0029] In some embodiments, the at least one input signal indicating a need to restart the engine to provide a required power output comprises an input signal generated in response to a user request.

[0030] In some embodiments, the at least one input indicating a need to restart power generation by the engine includes a request for power from a system of the vehicle that requires power to perform a function.

[0031] In some embodiments, the control system includes a controller as described in any of the preceding paragraphs and a transmission control module, wherein the transmission control module is configured to continuously provide signals to the controller, the signals being dependent on a current drive shaft speed, and to cause the reconnection of the engine to the drive shaft when the engine speed is at or below the desired engine speed.

[0032] According to a further aspect of the invention, a vehicle is provided which comprises a control system according to any one of the preceding paragraphs.

[0033] According to yet another aspect of the invention, a method for controlling an engine of a vehicle is provided, the method comprising: causing the engine's power generation to be turned off during movement of the vehicle in response to at least one criterion being met; causing the engine's power generation to be restarted in response to receiving at least one input signal indicating a need to restart the engine to provide a required power output; receiving a desired engine speed value dependent on a current drive shaft speed;Causing the motor to maintain a speed no greater than a target motor speed for a period after receiving the at least one input signal and until another signal is received indicating that reconnection of the motor to a drive shaft has been established, the target motor speed being dependent on the target motor speed value; and allowing the motor speed to exceed the target motor speed after reconnecting the motor to the drive shaft.

[0034] According to yet another aspect of the invention, there is provided a non-volatile storage medium having stored therein a program that, when run on a processor, causes the processor to: cause the engine's power generation to be turned off during movement of the vehicle in response to at least one criterion being met; cause the engine's power generation to be restarted in response to receiving at least one input signal indicating a need to restart the engine to provide a required power output; receive a desired engine speed value that is dependent on a current drive shaft speed;Causing the motor to maintain a speed no greater than a target motor speed for a period after receiving the at least one input signal and until another signal is received indicating that reconnection of the motor to a drive shaft has been established, wherein the target motor speed is dependent on the target motor speed value; and allowing the motor speed to exceed the target motor speed after reconnection of the motor to the drive shaft.;

[0035] According to yet another aspect of the invention, there is provided a method of controlling an engine and a transmission of a vehicle, the method comprising: enabling the engine to be disconnected from a drive shaft and power generation by the engine to be turned off during movement of the vehicle; and responsive to at least one input indicating a need to restart the engine to provide a required power output, causing the engine to restart power generation and reconnect the engine to the drive shaft, wherein the speed of the engine is limited so as not to exceed a desired engine speed when the engine is reconnected to the drive shaft, and wherein the desired engine speed is dependent on a current drive shaft speed.

[0036] According to yet another aspect of the invention, a control system is provided, comprising: an electronic processor having an electrical input for receiving at least one input signal and another signal; and an electronic storage device electrically coupled to the electronic processor and containing instructions stored therein, the instructions configured to cause the electronic processor to enable the motor to be disconnected from the drive shaft and to shut down power generation by the motor during movement of the vehicle;and responsive to at least one input indicating a need to restart the engine to provide a required power output, causing the engine to restart power generation and reconnect the engine to the drive shaft, wherein the control system is configured to limit the engine speed so that it does not exceed a desired engine speed when the engine is reconnected to the drive shaft, and wherein the desired engine speed is dependent on a current drive shaft speed;

[0037] Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples, and alternatives presented in the preceding paragraphs, in the claims, and / or in the following description and drawings, and in particular their individual features, may be considered independently of one another or in any combination. This means that all embodiments and / or features of any embodiment may be combined in any manner and / or in any combination, provided these features are not incompatible. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] 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. Figure 1 schematically shows a vehicle 103 comprising an engine 102 and a control system 101 for controlling the power output of the engine 102; Fig. 2 shows a flowchart outlining a method 200 that may be performed by the control system 101; Fig. 3 shows a flowchart showing an example of the processes that occur within the process of block 205 of Fig. 2 may be included; Fig. Fig. 4 schematically shows a vehicle 103 comprising an engine 102 and a control device 125 for controlling the power output of the engine 102; Fig. 5 shows a flowchart outlining an example of a method 500 that may be performed by the controller 125; Fig. 6 shows a flowchart showing an example of the processes that occur within block 504 of Fig. 5 can be carried out; Fig. 7 shows a graph illustrating an example of the operation of the control device 125 during process blocks 502 to 505 of Fig. 5 represents; Fig. 8 shows a second graph illustrating a second example of the operation of the control device 125 during process blocks 502 to 505 of Fig. 5 represents; Fig. 9 shows a third graph illustrating a third example of the operation of the control device 125 during process blocks 502 to 505 of Fig. 5 represents; Fig. 10 schematically shows an example of the control system 101 of Fig. 1 shows; and Fig. 11 schematically shows an example of the control device 125 of Fig. 4 shows. DETAILED DESCRIPTION

[0039] The figures illustrate a control system 101 for controlling an engine 102 of a vehicle 103 and for controlling the connection and disconnection of the engine 102 to / from a drive shaft 104, wherein the control system 101 is configured to enable the disconnection of the engine 102 from the drive shaft 104 and the shutdown of the power generation of the engine 102 during movement of the vehicle 103; and responsive to at least one input indicating a need to restart the engine 102 to provide a required power output, causing the engine 102 to restart power generation and the engine 102 to reconnect to the drive shaft 104, wherein the control system 101 is configured to limit the speed of the engine 102 to not exceed a desired engine speed when the engine 102 is reconnected to the drive shaft 104, and wherein the desired engine speed is dependent on a current drive shaft speed.

[0040] In some embodiments, the control system includes a controller 125 and a transmission control module 126, wherein the transmission control module 126 is configured to continuously provide signals to the controller 125, the signals dependent upon a current input shaft speed, and to cause the reconnection of the engine 102 to the input shaft 104 when the engine speed is at or below the desired engine speed.

[0041] The figures also illustrate a control device 125 for controlling an engine 102 of a vehicle 103, wherein the control device 125 is configured to cause the shutdown of power generation by the engine 102 during movement of the vehicle 103 in response to at least one criterion being met; to cause the restart of power generation by the engine 102 in response to at least one input signal indicating a need to restart the engine 102 to provide a required power output; to receive a target engine speed value in response to a current drive shaft speed;to cause the motor 102 to maintain a speed no greater than a desired motor speed for a period after receiving the at least one input signal and until receiving a further signal indicating that reconnection of the motor 102 to a drive shaft 104 has been achieved, the desired motor speed being dependent on the desired motor speed value; and to allow the motor speed to exceed the desired motor speed after receiving the further signal;

[0042] A vehicle 103 comprising an engine 102 and a control system 101 for controlling the power output of the engine 102 is shown in Fig. 1. The engine 102 comprises an internal combustion engine and may form a hybrid engine, for example, having an integrated starter generator 121, such as a belt-driven integrated starter generator. The starter generator 121 is arranged to generate electrical energy during operation of the engine 102 and to rotate the engine 102 to restart it. Alternatively, the engine 102 may be provided with a separate starter motor and an alternator for generating electrical energy.

[0043] In the present example, the engine 102 has an output shaft 105 connected to a torque converter 107 of an automatic transmission 123. The torque converter has an output shaft 122 connected to a clutch mechanism 106 of a transmission 108. The clutch mechanism 106 is arranged to open and close in response to instructions received from the control system 101 to engage and disengage gears within the transmission 108. When closed, the clutch mechanism 106 allows the torque provided by the engine 102, via the torque converter 107 and the transmission 108, to provide torque to a drive shaft 104 of a powertrain 124. When open, the clutch mechanism 106 disconnects the engine 102 from the drive shaft 104.

[0044] The drive shaft 104 is arranged to provide torque to the rear wheels 109A via a differential 110 and rear axles 113. In the present example, the vehicle 103 is a rear-wheel drive vehicle, and therefore only the rear wheels 109A are driven by the engine 102. However, it should be understood that in an alternative embodiment, the vehicle 103 may be a front-wheel drive vehicle, with only the front wheels 109B driven by the engine 102 via separate drive shafts (or half-shafts). Similarly, in another alternative embodiment, the vehicle 103 may be an all-wheel drive vehicle, with the rear wheels 109A driven via a first drive shaft and the front wheels 109B driven by a second drive shaft.

[0045] The vehicle 103 may also include an ABS (anti-lock braking system) of a known type, including an ABS controller 111 and sensors 112 on both the rear axles 113 and the front axles 114. The sensors 112 may be arranged to provide the ABS controller 111 with signals indicative of the rotational speed of each wheel 109A, 109B and / or the applied brake pressure. The ABS controller 111 may be arranged to provide the control system 101 with information indicative of the brake pressure and vehicle speed.

[0046] The vehicle 103 may also include various other electronic control units (ECUs) for control systems within the vehicle 103 that are not directly related to the control of the engine 102 or the transmission of power to the wheels 109A. These other electronic control units are shown in Fig. 1 as system control devices 115. The system control devices 115 may be arranged to control functions performed by various systems of the vehicle 103, such as controlling battery recharging or controlling the heating, air conditioning, and / or ventilation. Power required by the systems to perform the functions may be generated by the engine 102.

[0047] The vehicle 103 also includes a plurality of input devices 116 that enable the control system 101 to provide inputs for controlling the speed of the vehicle 103. The input devices 116 may include manual input devices, such as: a foot pedal for increasing engine torque (which may be referred to as an "accelerator pedal" or "throttle"); a brake pedal; a paddle shift actuator to allow a driver of the vehicle 103 to force a gear change in an automatic vehicle; and a mode selection device, such as a button or switch, to enable the control system 101 to change the driving mode, for example, to change from a power saving mode (or "ECO mode") to a "sport mode."

[0048] The ABS control device 111, the system control devices 115 and the input devices 116 may be arranged to communicate with the control system 101 via one or more communication buses 117.

[0049] The control system 101 may comprise a single electronic control unit or it may, as described below with reference to Fig. 4, may comprise several electronic control units, and the required processing and control functions may be distributed among the various ECUs.

[0050] An example of the control system 101, which includes an electronic control unit (ECU), is shown schematically in Fig. 10. The electronic control unit 101 includes a control device, which may include an electronic processor 1002 and an electronic storage device 1003 electrically coupled to the electronic processor 1002 and storing program instructions 1004 that, when executed by the processor 1002, configure it to perform the method described below.

[0051] The ECU 101 may include a transceiver 1005 to enable communication over the bus 117. The ECU 101 may include additional input and output interfaces 1006 to enable signals to be received from sensors such as sensors 118 and 119 and provide signals to the engine 102 and / or the starter generator 121 for starting the engine and controlling the power output and engine speed.

[0052] The instructions 1004 may be provided to the electronic storage device 1003 via a computer-readable storage medium 1007, such as a CD-ROM on which the instructions 1004 are stored.

[0053] Returning to Fig. 1, the control system 101 is configured to control the power output of the engine 102, for example, by controlling the amount of fuel injected. The control system 101 is also configured to control the clutch mechanism 106 to enable the connection and disconnection of the engine 102 to the drive shaft 104 and to select appropriate gears of the transmission 108.

[0054] To enable fuel conservation, the control system 101 is configured to enable the engine 102 to be disconnected from the drive shaft 104 and to shut down the power generation of the engine 102 when the vehicle 103 is stationary, and also during the movement of the vehicle 103 when one or more criteria are met indicating that the vehicle 103 is being brought to a stop. For example, the criteria may include the brakes being applied and the speed of the vehicle 103 being below a threshold speed, and both of these criteria may need to be met to enable the engine 102 to be disconnected and shut down.

[0055] Additionally, the control system 101 is configured to restart power generation by the motor 102 and reconnect the motor 102 to the drive shaft 104 in response to at least one input indicating a need to restart the motor 102 to provide a required power output.For example, if the engine 102 was previously disconnected from the driveshaft 104 and turned off, the control system 101 may receive an input signal from an input device 116, such as an accelerator pedal, a paddle shift actuator, or a mode selector switch, indicating that an increase in vehicle speed is required, or an input signal from the ABS control device 111 indicating that braking is no longer being applied or the vehicle speed is no longer below a threshold, or an input signal from one or more of the system control devices 115 indicating that power is required to perform a function controlled by it.

[0056] The control system 101 is configured to limit the speed of the motor 102 to no more than a target engine speed when the motor 102 is reconnected to the drive shaft 104. The target engine speed is determined by the control system 101 and is dependent on a current drive shaft speed, i.e., the speed of the drive shaft 104. This enables the smooth reconnection of the motor 102 to the drive shaft 104 and minimizes vehicle noise, vibration, and harshness (NVH) caused by the reconnection. This prevents, for example, occupants of the vehicle 103 from experiencing a sudden acceleration of the vehicle 103 at the moment of reconnection.

[0057] An overview of a method 200 that may be performed by the control system 101 is shown in the flowchart of Fig. 2. Method 200 may be performed while vehicle 103 is moving, i.e., while the vehicle speed relative to the ground / road is not zero. At block 201 of method 200, it is determined whether all criteria for shutting down power generation by engine 102 have been met. The criteria may include one or more of the following criteria: (i) the vehicle speed, i.e. the speed of the vehicle relative to the ground / road, is less than a threshold speed, for example 5 kilometres per hour, 10 kilometres per hour, 20 kilometres per hour or another value; (ii) a measured brake pressure is greater than a threshold pressure; (iii) reverse gear is not engaged; (iv) a user-selectable mode that prevents the engine from shutting down power generation has not been selected; and (v) the accelerator pedal input is lower than a threshold value.

[0058] In one embodiment, all criteria (i) through (v) must be met to enable shutdown of power generation by the engine 102 during vehicle motion.

[0059] If the required criteria are met at block 201 of method 200, at block 202, the control system 101 enables the engine 102 to be disconnected from the drive shaft 104 by disengaging the clutch mechanism 106 and shutting down power generation by the engine 102 even while the vehicle 103 is moving. When the vehicle 103 is moving with the engine 102 off and in the disconnected state, the control system 101 repeatedly determines at block 203 whether an input signal has been received indicating a need to restart the engine 102 to provide a required power output. When such an input signal is received, the control system 101 causes the motor 102 to restart at block 204, and at block 205, the speed of the motor 102 is limited to no more than a desired motor speed that is dependent on a current drive shaft speed during reconnection of the motor 102 to the drive shaft 104.

[0060] The target engine speed may be independent of the input signal indicating the required power output. That is, the target engine speed may be independent of the power output required by the system or device that provided the input signal.

[0061] The engine speed, i.e., the speed of the output shaft 105 of the engine 102, can be determined from a signal received by a sensor 118 provided on the output shaft 105 of the engine 102. The current drive shaft speed can be determined in a similar manner from a signal received by a sensor 119 configured to measure the speed of the drive shaft 104. Alternatively, the drive shaft speed can be determined from the vehicle speed, the road wheel radius, and the gear ratio provided by the differential 110. The vehicle speed can be obtained, for example, from signals provided by the ABS controller 111 or, alternatively, from a global navigation satellite system (GNSS) unit, such as a GPS (Global Positioning System) unit (not shown), installed in the vehicle 103.

[0062] The control system 101 may be configured to set the desired engine speed to be dependent on the idle speed of the engine 102 when the drive shaft speed is at or below a threshold. That is, when the speed of the drive shaft 104 is very low or zero, the control system 101 may be arranged to set the desired engine speed to the idle speed of the engine 102 or within a predetermined speed of the idle speed. If the drive shaft speed is above a threshold, the desired engine speed may be determined from the drive shaft speed. For example, the desired engine speed may be determined to be within a predefined difference of an expected engine speed, which may be derived from the current drive shaft speed and the ratio of a gear to be engaged when the engine 102 is reconnected via the clutch mechanism 106.That is, the target engine speed may be determined to be within a predefined difference from the speed that the engine 102 would have at the current speed of the drive shaft 104 if the engine 102 were connected to the drive shaft 104 (and without clutch slip). The predefined difference may be between 0 and 60 revolutions per minute.

[0063] Therefore, the target engine speed may be selected such that, when the engine 102 is operating at the target engine speed, it would cause the input side of the clutch mechanism 106 to rotate at the same speed or within a predefined difference of an output side of the clutch mechanism 106. The speed difference may depend on whether the clutch mechanism 106 is configured to allow clutch slippage during re-engagement.

[0064] Examples of the processes that may be included in the process of block 205 are shown in the flowchart of Fig. 3. At block 301, it may be determined whether the drive shaft speed is below a threshold, and if so, the desired engine speed at block 302 may be caused to depend on the idle speed of the engine 102. Alternatively, if it is determined at block 301 that the drive shaft speed is not below a threshold, a desired engine speed may be determined from a measured speed value, such as the current drive shaft speed or the vehicle speed, and the ratio of a gear to be engaged at block 303. If the desired engine speed is determined from the vehicle speed, the determination may also take into account the gear ratio provided by the differential 110.

[0065] At block 304, the control system 101 causes the engine 102 to reach a speed no greater than the desired engine speed and causes the clutch mechanism 106 to close to reconnect the engine 102 to the input shaft 104 when the engine speed is no greater than the desired engine speed. As described in more detail below, the engine 102 may reach a speed greater than the desired engine speed before reconnection is enabled, but the control system 101 ensures that the engine speed is at or below the desired engine speed at the time reconnection occurs.

[0066] As in Fig. 1, the control system 101 may be embodied in a single electronic control unit having a plurality of different software modules, each associated with a corresponding function. Thus, the control system 101 may include a controller 125 or a powertrain control module (PCM) 125 arranged to control the operation of the engine 101, and a transmission control module (TCM) 126 arranged to control the operation of the clutch mechanism 106 and the gear selection in the transmission 108. As shown in Fig. 4, the control device 125 and the TCM 126 may alternatively each be provided in a respective electronic control unit arranged to communicate via the communication bus 117. All other features of the vehicle 103 of Fig. 4 can be the same as for vehicle 103 of Fig. 1, and therefore the features have been given the same reference numerals.

[0067] An example of the control device 125 of Fig. 4 is schematically shown in Fig. 11. The control device 125 of Fig. 11 includes an electronic control unit (ECU) 125 having a controller that may include an electronic processor 1102 and an electronic storage device 1103 electrically coupled to the electronic processor 1102 and having program instructions 1104 stored therein that, when executed by the processor 1102, configure it to perform the method described below.

[0068] The ECU 125 may include a transceiver 1105 to enable communication over the bus 117. The ECU 125 may include additional input and output interfaces 1106 to enable signals from sensors such as sensor 118 to be received and provide signals to the engine 102 and / or the starter generator 121 to start the engine and control the power output and engine speed.

[0069] The instructions 1104 may be provided to the electronic storage device 1103 via a computer-readable storage medium 1107, such as a CD-ROM on which the instructions 1104 are stored.

[0070] In relation to Fig. 1 and Fig. 4, the controller 125 may be configured to receive input signals from the ABS controller 111 relating to the applied brake pressure and the current speed of the vehicle 103; from the system controllers 115 indicating whether power is required from the engine 102; from the input devices 116 indicating whether the respective criteria are met, for example, whether the accelerator pedal input is less than a threshold; from the sensor 118 indicating the current engine speed; and from the TCM 126.

[0071] In one embodiment, when the engine 102 has been shut down during movement of the vehicle 103, signals are continuously provided from the TCM 126 to the controller 125, including a desired engine speed value indicating an engine speed required to re-engage the clutch mechanism. ("Continuously provided signals" means that the signals are provided continuously or repeatedly frequently.)

[0072] The target engine speed value may be the actual target engine speed that the engine 102 must reach for the clutch mechanism to reengage. In this case, the TCM 126 performs the determination of the target engine speed from, for example, the input shaft speed and the gear ratio to be used when reconnecting occurs, or the vehicle speed, the radius of the road wheels 109A, and the gear ratios provided by the transmission 123 and the differential 110. Alternatively, the target engine speed value provided to the controller 125 may indicate a speed, such as the input shaft speed, that may be provided along with the gear ratio to be used when reconnecting occurs, and the controller 125 is then arranged to determine the target engine speed from the information received from the TCM 126.

[0073] The TCM 126 may also be configured to provide signals to the controller 125 indicating the status of the clutch mechanism 106, i.e., whether the clutch mechanism is engaged or disengaged.

[0074] The controller 125 is configured to provide output signals to the engine 102 to start it and to control the engine speed. For example, if the engine 102 is a hybrid engine, it can be started via its integrated starter generator 121. The controller 125 is also configured to provide signals to the TCM 126 indicating that disengagement of the clutch mechanism 106 is required when the engine 102 is to be shut down.

[0075] An example of a method 500 that may be performed by controller 125 is outlined in the flowchart of Figure 5. At block 501, engine 102 is caused to shut down power generation during movement of vehicle 103 depending on whether at least one criterion is met. The at least one criterion may be any of the criteria labeled (i) through (v) described above. Before shutting down engine 102, controller 125 may provide a signal to TCM 126 instructing it to cause disengagement of clutch mechanism 106. Controller 125 may then await confirmation from TCM 126 that the clutch mechanism is disengaged before shutting down engine 102.

[0076] When the engine 102 is off, the engine 102 is started at block 502 in response to the receipt of at least one input signal indicating a need to restart the engine 102 and provide a required power output. This may be accomplished by providing signals to the integrated starter generator 121 and to the fuel injection system of the engine 102.

[0077] At block 503, a desired engine speed value is received, for example, from the TCM 126, which is dependent on the current input shaft speed. It should be noted that although block 503 is depicted after block 502, the process of block 503 may be performed before block 502.

[0078] At block 504, the engine 102 is caused to maintain a speed of no more than a desired engine speed for a period of time after receiving the at least one input signal and until another signal is received, for example, from the TCM 126, indicating that reconnection of the drive shaft 104 to the engine 102 has been established. The desired engine speed depends on the desired engine speed value received in block 503, and in one embodiment, the desired engine speed value may actually be the desired engine speed. However, the desired engine speed value may be another speed, such as a drive shaft speed or a vehicle speed, and the desired engine speed may be determined from the desired engine speed value, for example, using the ratio of the gear to be engaged.

[0079] After block 504, in which the reconnection is confirmed by receiving the additional signal, the engine speed may exceed the target engine speed in block 505. The speed of the engine 102 may be varied as requested by the input devices 116.

[0080] An example of the processes described in block 504 of Fig. 5 can be executed is shown in a flow chart in Fig. 6. At block 601, the speed of the engine 102 is increased to a desired engine speed at a rate dependent on the at least one input signal. For example, if an input signal is received from an accelerator pedal indicating that rapid acceleration of the vehicle is required, the engine speed may be increased at a higher rate than if an input signal is received from the accelerator pedal indicating that a relatively slower acceleration is required.

[0081] At block 602, the engine 102 is caused to maintain a speed no greater than the desired engine speed for a period of time after receiving the at least one input signal and until the further signal is received indicating that reconnection of the drive shaft 104 to the engine 102 has been established.

[0082] Fig. Figure 7 shows a graph illustrating an example of the operation of the controller 125 during process blocks 502 to 505 of Fig. 5 in response to receiving an input signal from a user-operated input device 116, such as an accelerator pedal. A first line 701 represents the expected engine speed given the current speed of the vehicle 103 and the currently selected gear. That is, the first line 701 represents the speed that the engine 102 would have at the current speed of the vehicle 103 if the engine 102 were connected to the input shaft 104 (and with no clutch slip). A second line 702 represents the actual engine speed, for example, measured by the sensor 118 on the output shaft 105 of the engine 102. A third line 703 represents the desired engine speed value provided by the TCM 126 to the controller 125.

[0083] In the present example and the examples of Fig. 8 and Fig. 9, the desired engine speed value provided by the TCM 126 is set to zero when no control of the engine speed is required with respect to reconnecting the engine to the drive shaft, and the controller 125 is configured to interpret the zero value accordingly.

[0084] To simplify the description, it is also assumed that in the present example, when engine speed control is required, the target engine speed value is equal to the desired engine speed. (i.e., no additional processing of the target engine speed value by controller 125 is required to determine the desired engine speed.)

[0085] In a first period 704, the engine 102 is in a stopped state, and therefore, line 702 shows that the engine speed is zero. Line 701 shows that the expected engine speed is positive because the vehicle is moving. Line 703 is zero because no reconnection of the engine 102 to the drive shaft 104 occurs during the first period 704. At the end of the first period 704, at time t1, an input signal is received from a user-operated input device 116, such as an accelerator pedal, causing the desired engine speed value (line 703) to increase to a new value. In the present example, the transmission of the vehicle 103 does not have the opportunity to slip the clutch mechanism 106, so the desired engine speed equals the expected engine speed (line 701).In response to receiving the input signal from input device 116 at time t1, engine 102 is started in a second period 705, for example, by integrated starter generator 121. Therefore, the engine speed (line 702) increases during second period 705.

[0086] When the engine starts at time t2, the speed of the engine 102 begins to increase more rapidly during a third period 706. However, the controller 125 only allows the engine speed (line 702) to increase until it equals the desired engine speed (line 703). When the engine speed is approximately equal to, but not more than, the desired engine speed, a fourth period 707 begins at time t3, during which reconnection occurs. At time t3, the controller 125 may provide a signal to the TCM 126 indicating that closing of the clutch mechanism 106 may begin. During this fourth period 707, the engine speed is maintained at or below the desired engine speed, and the clutch mechanism 106 is closed to reconnect the engine 102 to the input shaft 104.

[0087] When reconnection is complete, the TCM 126 may send another signal to the controller 125 at time t4 to confirm that reconnection by the clutch mechanism 106 is complete, and the desired engine speed value again indicates that no control of the engine speed by the TCM 126 is required with respect to reconnecting the engine to the drive shaft. Consequently, the controller 125 may then increase the engine speed (and the vehicle speed) as requested by the input signal from the user input device 116 in a fifth period 708.

[0088] Fig. Figure 8 shows a second graph illustrating a second example of the operation of the control device 125 during method blocks 502 to 505 of Fig. 5 in response to receiving an input signal from a user-operated input device 116, such as an accelerator pedal. A first line 801 represents the expected engine speed given the current speed of the vehicle 103 and the currently selected gear. A second line 802 represents the engine speed, for example, as measured by sensor 118 on the output shaft 105 of the engine 102. A third line 803 represents the desired engine speed value provided by the TCM 126 to the controller 125.

[0089] In this example, the engine 102 is off during a first period 804, and therefore line 802 shows that the engine speed is zero. Line 801 shows that the expected engine speed is positive because the vehicle 103 is moving. Line 803 is zero because no reconnection of the engine 102 to the drive shaft 104 occurs during the first period 804. At the end of the first period 804, at time t1, an input signal is received from a user-operated input device 116, such as an accelerator pedal, causing the desired engine speed value (line 803) to increase to a new value. In the present example, the clutch mechanism 106 may be slipping, and the user input indicates that acceleration is required. Consequently, in a second period 805 after time t1, the target engine speed value (line 803) is set to be above the expected engine speed (line 801).This allows the motor 102 to achieve a higher speed and torque, which subsequently allows the clutch mechanism 106 to slip to deliver torque to the idler wheels 109B ( . Fig. 1 and Fig. 4) to be created.

[0090] During the second period 805, the engine 102 is started, for example, by the integrated starter generator 121, and therefore the engine speed increases (line 802). At time t2, when the engine 102 starts, a third period 806 begins, during which the engine speed (line 802) increases more rapidly toward the target engine speed (line 803). However, the controller 125 only allows the engine speed (line 802) to increase to approximately the same level as the target engine speed (line 803) and does not exceed the target engine speed.

[0091] When the engine speed (line 802) is approximately equal to the target engine speed (line 803), but not more than the target engine speed, a fourth period 807 begins at time t3, during which reconnection occurs. During the fourth period 807, the engine speed (line 802) is maintained at or below the target engine speed (line 803), and the clutch mechanism 106 is closed to reconnect the engine 102 to the drive shaft 104. However, during closing, the clutch mechanism 106 slips to allow some engine torque to be applied to the road wheels 109A, and consequently, the speed of the vehicle 103 may increase during this period.During the fourth period 807, the desired engine speed (line 803) is continuously updated, and therefore increasing the vehicle speed results in an increase in the desired engine speed (line 803), which in turn allows a corresponding increase in the engine speed (line 802) while maintaining it at or below the desired engine speed.

[0092] The fourth period ends at time t4 when the reconnection of the motor 102 to the input shaft 104 is complete, and the TCM 126 sets the desired engine speed value to indicate that control of the engine speed for reconnection is no longer required, and another signal may be provided from the TCM 126 to the controller 125 to confirm that the clutch mechanism 106 is engaged.

[0093] Consequently, after time t4, the controller 125 may increase the engine speed (and the vehicle speed) as requested by the input signal from the user input device 116.

[0094] Fig. 9 shows a third graph illustrating a third example of the operation of the control device 125 during method blocks 502 to 505 of Fig. 5 in response to receiving an input signal from a system controller 115, such as the ECU arranged to control battery charging. A first line 901 represents the expected engine speed given the current speed of the vehicle 103 and the currently selected gear. A second line 902 represents the engine speed, for example, measured by sensor 118 on the output shaft 105 of the engine 102. A third line 903 represents the desired engine speed value provided by the TCM 126 to the controller 125.

[0095] In this example, the engine 102 is turned off in a first period 904, and therefore line 902 shows that the engine speed is zero. Line 901 shows that the expected engine speed is positive because the vehicle is moving. Line 903 is zero because no reconnection of the engine 102 to the drive shaft 104 occurs in the first period 904. At the end of the first period 904, at time t1, an input signal is received from a system controller 115, for example, an ECU arranged to control battery charging, which causes the target engine speed value (line 903) to increase to a new value. In a second period 905, after time t1, the target engine speed value (line 903) is adjusted to be equal to the expected engine speed (line 901).

[0096] During the second period 905, the engine 102 is started and therefore the engine speed increases (line 902). At time t2, when the engine 102 starts, a third period 906 begins in which the engine speed (line 902) increases toward the target engine speed (line 903). In the present example, the controller 125 causes the engine speed (line 902) to increase more quickly than in previous examples and may exceed the target engine speed (line 903). However, the engine speed is reduced to equal the target engine speed (line 903) before a fourth period 907 begins at time t3, in which the clutch mechanism 106 is re-engaged to reconnect the engine 102 to the input shaft 104.

[0097] Allowing the engine speed (line 902) to exceed the desired engine speed (line 903) may also be permitted when the engine restart is caused by an input signal received from an input device 116. This may allow the engine speed to reach the desired engine speed more quickly, which may be necessary, for example, to cause rapid acceleration of the vehicle 103. However, the engine speed is controlled to be reduced to a value no higher than the desired engine speed before the connection of the engine 102 to the drive shaft 104 begins.

[0098] In the fourth period 907 of the graph of Fig. 9, the engine speed (line 902) is maintained at the same level as the expected engine speed (line 901), and consequently the occupants of the vehicle 103 do not experience any acceleration upon reconnection.

[0099] The fourth period ends at time t4, at which time the reconnection of the motor 102 to the input shaft 104 is completed, the TCM 126 sets the desired engine speed value to zero, indicating that control of the engine speed for reconnection is no longer required, and another signal may be provided from the TCM 126 to the controller 125 to confirm that the clutch mechanism 106 is engaged.

[0100] In a fifth period 908 after reconnection is completed at time t4, the engine speed may be controlled by user inputs received from the input devices 116.

[0101] For the purposes of this disclosure, it is understood that the control device(s) described herein may each comprise a control unit or a computing device having one or more electronic processors. A vehicle and / or a system thereof may comprise a single control unit or electronic control device, or alternatively, different functions of the control device(s) may be implemented or hosted in different control units or control devices. A set of instructions could be provided that, when executed, cause the control device(s) or control unit(s) to implement the control techniques (including the described methods) described herein.The set of instructions may be embedded in one or more electronic processors, or alternatively, the set of instructions may be provided as software to be executed by one or more electronic processors. For example, a first control device may be implemented in software running on one or more electronic processors, and one or more other control devices may also be implemented in software running on one or more electronic processors, optionally the same processor(s) as the first control device. However, it is to be understood that other arrangements are also usable and the present disclosure is therefore not limited to any particular arrangement. In any event, the set of instructions described above may be embodied in a computer-readable storage medium (e.g.,a non-volatile storage medium) which may include a mechanism for storing information in a form readable by a machine or electronic processor / computing device, including, but not limited to: a magnetic storage medium (e.g., floppy disk); 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 media for storing such information / instructions.

[0102] The Fig. 2, Fig. 3, Fig. 5 and Fig.The blocks illustrated in Figure 6 may represent steps in a method and / or portions of code in computer program 1004. The depiction of a particular order for the blocks does not necessarily imply a required or preferred order for the blocks, and the order and arrangement of the blocks may be varied. Furthermore, some steps may be omitted.

[0103] Although the embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be understood that changes may be made to the examples shown without departing from the scope of the invention as claimed in the appended claims.

[0104] Features described in the preceding description may be used in combinations that differ from the explicitly described combinations.

[0105] Although functions have been described with reference to certain features, those functions can be performed by other features, whether or not they have been described.

[0106] Although features have been described with reference to particular embodiments, these features may also be present in other embodiments, whether described or not.

[0107] Although the applicant has endeavoured in the foregoing description to draw attention to those features of the invention to which he considers particular importance, it is to be understood that he claims protection in respect of any patentable feature or combination of features referred to above and / or shown in the drawings, whether or not particular importance has been attached to it.

Claims

[1] A control device for controlling an engine of a vehicle, the control device comprising a control device configured to: to switch off the engine's power generation while the vehicle is moving, depending on whether at least one criterion is met; initiate a restart of power generation by the engine in response to at least one input signal indicating a need for the engine to restart in order to provide a required power output; to receive a target engine speed value as a function of a current drive shaft speed; to cause the motor to maintain a speed no greater than a target motor speed during a period after receipt of the at least one input signal and until a further signal is received indicating that reconnection of the motor to a drive shaft has occurred, the target motor speed being dependent on the target motor speed value; and after receiving the further signal, to allow the engine to exceed the target engine speed, wherein the controller is configured to determine a target engine speed dependent on the idle speed of the engine depending on whether the drive shaft speed is at or below a threshold. [2] The control device according to claim 1, wherein the target engine speed is within a predefined speed of the idle speed of the engine. [3] A control device according to any one of the preceding claims, wherein the control device is configured to allow the engine speed to rise above the target engine speed and fall to the target engine speed before the drive shaft is reconnected to the engine. [4] Control device according to one of the preceding claims, wherein the desired engine speed is independent of the required power indicated by the at least one input signal. [5] Control device according to one of the preceding claims, wherein the target engine speed value is dependent on the current drive shaft speed and the ratio of a gear to be engaged. [6] Control device according to one of claims 1 to 4, wherein the control device is configured to determine the target engine speed from the target engine speed value and the gear ratio of a gear to be engaged. [7] A control device according to any one of the preceding claims, wherein: an expected engine speed can be derived from the ratio of the gear to be engaged and a speed of the vehicle or the current drive shaft speed; and the desired engine speed is arranged to be within a predefined difference of the expected engine speed. [8] Control device according to claim 7, wherein the predefined difference comprises a difference between 0 and 60 revolutions per minute. [9] A control device according to any one of the preceding claims, wherein the control device is configured to continuously receive signals from a transmission control module, the signals comprising a desired engine speed value dependent on a current drive shaft speed, the transmission control module being configured to cause the engine to reconnect to the drive shaft when the engine speed is at or below the desired engine speed. [10] The control device of any one of claims 1 to 9, wherein the at least one input signal indicating a need to restart the engine to provide a required power output comprises an input signal generated in response to a user input. [11] A control device according to any one of claims 1 to 10, wherein the at least one input signal indicating a need to restart the engine to provide a required power output comprises an input signal indicating that a brake pressure has been reduced below a threshold. [12] A control device according to any one of claims 1 to 11, wherein the at least one input signal indicating a need to restart the engine to provide a required power output comprises an input signal indicating a user request to accelerate the vehicle. [13] A control device according to any one of claims 1 to 12, wherein the at least one input signal indicating a need to restart the engine to provide a required power output comprises an input signal indicating a user request for a gear change. [14] The control device of any one of claims 1 to 13, wherein the control device is configured to cause the restart of power generation by the motor and to increase the motor speed at a rate dependent on the at least one input signal prior to reconnecting the motor to the drive shaft. [15] A control device according to any one of the preceding claims 1 to 14, wherein the at least one input indicating a need to restart power generation by the engine comprises a request for power from a system control device of the vehicle requiring power to perform a function. [16] The control device of claim 15, wherein the function comprises at least one of the group comprising battery charging; heating; ventilation; and air conditioning. [17] Control device according to one of claims 1 to 16, wherein the at least one criterion comprises at least one of the following: the vehicle speed falling below a first threshold value; a brake pressure exceeding a second threshold value. [18] A control device comprising an electronic processor having an electrical input for receiving at least one input signal and one further signal; and an electronic storage device electrically coupled to the electronic processor and having instructions stored therein, the instructions configured to cause the electronic processor to: to switch off the engine's power generation while the vehicle is moving, depending on whether at least one criterion is met; initiate a restart of power generation by the engine in response to at least one input signal indicating a need for the engine to restart in order to provide a required power output; to receive a target engine speed value as a function of a current drive shaft speed; to cause the motor to maintain a speed no greater than a target motor speed during a period after receipt of the at least one input signal and until a further signal is received indicating that reconnection of the motor to a drive shaft has occurred, the target motor speed being dependent on the target motor speed value; and after receiving the further signal, to allow the engine to exceed the target engine speed, wherein the controller is configured to determine a target engine speed dependent on the idle speed of the engine depending on whether the drive shaft speed is at or below a threshold. [19] A control system for controlling an engine of a vehicle and for controlling the connection and disconnection of the engine to / from a drive shaft, the control system being configured to to enable the engine to be disconnected from the drive shaft and to switch off the engine's power generation while the vehicle is moving; and in response to at least one input indicating a need to restart the engine to provide a required power output, to cause the engine to restart power generation and to reconnect the engine to the drive shaft, wherein the control system is configured to limit the speed of the engine such that it is no more than a target engine speed upon reconnecting the engine to the drive shaft, and wherein the target engine speed is dependent on a current drive shaft speed, wherein the control system is configured to determine a desired engine speed dependent on the idle speed of the engine depending on whether the drive shaft speed is at or below a threshold. [20] A control system according to claim 19, wherein the desired engine speed is independent of the input indicating the required power output. [21] A control system according to claim 19 or claim 20, wherein the desired engine speed is dependent on the current drive shaft speed and the ratio of a gear to be engaged. [22] A control system according to any one of claims 19 to 21, wherein the at least one input signal indicating a need to restart the engine to provide a required power output comprises an input signal generated in response to a user input. [23] A control system according to any one of claims 19 to 22, wherein the at least one input indicating a need to restart power generation by the engine comprises a request for power from a system of the vehicle that requires power to perform a function. [24] A control system according to claim 19, comprising a control device according to any one of claims 1 to 18 and a transmission control module, wherein the transmission control module is configured to continuously provide signals to the control device, the signals being dependent on a current drive shaft speed, and to cause the reconnection of the engine to the drive shaft when the engine speed reaches or falls below the desired engine speed. [25] A vehicle comprising a control system according to any one of claims 19 to 24. [26] A method for controlling an engine of a vehicle, the method comprising: Initiating the shutdown of the engine's power generation while the vehicle is moving, depending on at least one criterion being met; causing the engine to restart power generation in response to receiving at least one input signal indicating a need to restart the engine to provide a required power output; Receiving a desired engine speed value that is dependent on a current drive shaft speed; causing the motor to maintain a speed no greater than a target motor speed for a period after receipt of the at least one input signal and until a further signal is received indicating that reconnection of the motor to a drive shaft has been established, the target motor speed being dependent on the target motor speed value; and Allow the engine speed to exceed the target engine speed after reconnecting the engine to the drive shaft, wherein, depending on whether the drive shaft speed is at or below a threshold value, a target engine speed is determined as a function of the idle speed of the engine.

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