Vehicle control system and procedures

Abstract

Control system (140, 240) for a hybrid vehicle (100) with an engine (121, 221) and at least one electric machine (123C), each configured to cause torque to be applied to an input shaft (124IN) of a transmission (124), wherein the control system (140, 240) is configured to: to cause a negative net drive torque to be applied to the input shaft (124IN) of the gearbox (124) in a direction opposite to the direction of travel of the vehicle (100), using the motor (121, 221) and the electric machine (123C), in order to brake; to determine when a gear change is imminent that requires the application of a non-negative torque to the input shaft (124IN) of the transmission (124); and, If a negative net drive torque is applied to the input shaft (124IN) of the transmission (124) and it is determined that a gear change is imminent which requires the application of a non-negative torque, a non-negative net drive torque is temporarily applied to the input shaft (124IN) by causing the electric machine (123C) to apply a positive torque to the input shaft (124IN) of the transmission (124) sufficient to compensate for the negative torque applied by the motor (121, 221), and braking force is applied to one or more wheels (111, 112, 114, 115) of the vehicle (100) by a second braking device to compensate for the reduction of the negative drive torque applied to the input shaft (124IN) of the transmission (124) during the gear change.

Description

ADMISSION BY REFERENCE

[0001] The entire contents of the concurrently pending UK patent application GB2499252 and UK patents GB2492748, GB2492655, GB2325716, GB2308415, GB2341430, GB2382158, GB2381597 and GB2483371 are expressly incorporated herein by reference. The contents of US patent application US2003 / 0200016 are also hereby incorporated by reference. TECHNICAL AREA

[0002] The present invention relates to a control system for a vehicle, preferably, but not exclusively, for a hybrid electric vehicle. Embodiments of the present invention provide a control system for a vehicle, a vehicle, a method for controlling a vehicle, a non-transient computer-readable carrier medium with a computer-readable code, a computer program product executable on a processor, a computer-readable medium, and a processor. STATE OF THE ART

[0003] Parallel hybrid electric vehicles are known to be equipped with an internal combustion engine and an electric drive motor, each capable of providing drive torque to propel the vehicle. In some known configurations, the internal combustion engine and the electric drive motor can provide drive torque alone or in combination.

[0004] The drive motor is powered by a traction battery. In some so-called "mild hybrid" vehicles, the drive motor is configured to provide torque amplification, supplementing the drive torque generated by the engine. The drive motor can also be configured to act as a generator, applying negative drive torque to the drive system to create regenerative braking. The battery can be recharged when the motor is operating as a generator.

[0005] In manchen bekannten Fahrzeugen kann das Fahrzeug in einem Elektrofahrzeug-(EV-)Modus betrieben werden, wobei der Motor abgeschaltet ist und der elektrische Antriebsmotor für Antriebsmoment sorgt, um das Fahrzeug nach Bedarf zu fahren. Das Fahrzeug kann auch in einem Parallelmodus betrieben werden, wobei der Motor eingeschaltet ist und der elektrische Antriebsmotor betriebsfähig ist, um entweder Antriebsmoment zusätzlich zu dem Motor in einem parallelen Verstärkungsmodus zu liefern oder um elektrische Ladung zu erzeugen, um die Antriebsbatterie in einem parallelen Lademodus aufzuladen. Ein Fahrzeugsteuersystem bestimmt, wann der Verbrennungsmotor ein- oder auszuschalten ist und wann eine Kupplung Ko zwischen Motor und Getriebe zu öffnen oder zu schließen ist. In manchen Fahrzeugen ist der elektrische Antriebsmotor in das Getriebe integriert.

[0006] US 2010 0 280 695 A1 relates to a braking procedure for a hybrid vehicle comprising a powertrain controlled by a powertrain computer and a hydraulic braking system controlled by a brake computer.

[0007] EP 2 474 434 A1 relates to a vehicle propulsion system comprising an internal combustion engine and an electric motor.

[0008] US 6,126,251 A relates to a brake control device for an electric vehicle, in particular a device for reducing the vehicle speed using the regenerative braking of an electric motor and the friction braking force of a friction brake.

[0009] US5399000A relates to a braking system in an electric vehicle with a trailing wheel that can be hydraulically braked by actuating a brake actuating element, and a drive wheel that is connected to a motor that uses a battery as an energy source and can be hydraulically and regeneratively braked by actuating the brake actuating element.

[0010] US 2012 0 265 382 A1 concerns the area of ​​powertrains for hybrid vehicles and, in particular, the modulation of torque in a powertrain for hybrid vehicles during a gear ratio change that occurs during regenerative braking.

[0011] The applicant of the present invention identified a problem when attempting to use certain transmissions in known hybrid electric vehicle powertrains. Certain gear changes require a non-negative drive torque to be applied to the transmission input shaft during the gear change. It should be noted that if the hybrid vehicle has an electric motor that, in addition to the motor, applies negative drive torque to the transmission input shaft to effect regenerative braking, the amount of negative drive torque at the input shaft can be large compared to the amount when braking force is applied directly to the wheels by a braking system instead of via the transmission input shaft.

[0012] Embodiments of the present invention attempt to mitigate this problem in order to provide an electric or hybrid electric vehicle capable of regenerative braking without unduly impairing vehicle performance. BRIEF SUMMARY OF THE INVENTION

[0013] Embodiments of the inventions are to be understood with reference to the attached claims.

[0014] Aspects of the present invention provide a control system, a vehicle and a method.

[0015] In one aspect of the invention for which protection is claimed, a control system is provided for a vehicle with at least one electric machine configured to cause torque to be applied to an input shaft of a transmission, wherein the control system is configured to: to cause a negative net drive torque to be applied to the input shaft of the transmission in a direction opposite to the direction of travel of the vehicle, at least partially by means of the electric machine, in order to brake; to determine when a gear change is imminent that requires the application of a non-negative torque to the transmission's input shaft; and, If a negative net drive torque is applied to the input shaft of the transmission and it is determined that a gear change is imminent which requires the application of a non-negative torque, to temporarily cause a non-negative drive torque to be applied to the input shaft and to cause braking force to be applied to one or more wheels of the vehicle by a second braking device in order to compensate for the reduction of the negative drive torque applied to the input shaft of the transmission while the gear change is taking place.

[0016] The vehicle can be a purely electric vehicle or a hybrid vehicle with a motor, whereby the negative net drive torque is caused by at least one of the motor and the electric machine.

[0017] Embodiments of the present invention have the advantage that an electric or hybrid electric vehicle can be provided that is capable of regenerative braking and easier gear changes in transmissions that require a non-negative drive torque at the input shaft thereof while certain gear changes take place.

[0018] It should be noted that the braking force can be applied to one or more wheels by a secondary braking device comprising a friction-based service braking system and / or any other suitable braking device. Such a braking device may include an electric machine located downstream of the transmission along a torque path from the transmission to one or more wheels. For example, such an electric machine may be located on an axle of the vehicle, such as a rear axle, as in an electric rear-wheel drive (ERAD) arrangement, or by means of wheel-hub-mounted electric machines, or the like.

[0019] If applicable, the system is configured to receive a drive request signal indicating an amount of required drive torque from a vehicle drivetrain, and the system is configured to cause negative drive torque to be exerted at least partially by the electric machine in at least partial dependence on the drive request signal.

[0020] It should be noted that the drive request signal can indicate the position of an accelerator pedal control unit, such as an accelerator pedal. If the vehicle is moving and the drive request signal indicates that the accelerator pedal control unit is in a substantially fully released state, the control system may determine that the electric machine should operate in a coasting state, in which the electric machine applies negative torque to the drive system to simulate engine coasting, also known as compression braking. It should be noted that if the engine remains coupled to the drive system when the accelerator pedal control unit is in the released state, the engine can provide coasting braking in addition to that provided by the electric machine. It should also be noted that, in the case of an accelerator pedal, the transition of the pedal from a depressed to a released state may be referred to as "tipping."

[0021] In some embodiments, the control system may be arranged to cause the electric machine to exert an amount of negative torque simulating engine braking sufficient for the net amount of engine braking to be equivalent to that of a motor of a size comparable to that required to deliver the combined maximum amount of positive torque that the electric machine and the motor can produce, i.e., an amount greater than that of the vehicle's built-in motor alone.In some alternative embodiments, the control system may be arranged to cause the electric machine to apply an amount of negative torque such that the net amount of applied negative torque is greater than that which would be supplied by a motor of a size comparable to that which would be required to supply the combined maximum amount of positive torque that the electric machine and the motor can produce.

[0022] Optionally, the system is configured to receive a brake force request signal indicating an amount of brake force required, and the system is configured to cause negative drive torque to be exerted at least partially by the electric machine in at least partial dependence on the brake force request signal.

[0023] It is understood that the braking force request signal can be generated, for example, by a user pressing a brake pedal or by a speed control system such as adaptive cruise control. The amount of negative torque exerted by the electric motor providing regenerative braking can therefore be increased in response to this signal. By exerting negative torque, the electric motor can generate electrical energy, thereby effecting regenerative braking.

[0024] Alternatively or additionally, the second braking device can respond to braking torque requests via the brake force request signal.

[0025] In a hybrid vehicle, the system may be configured to cause a non-negative net drive torque to be applied at least partially to the transmission input shaft by causing the engine to apply a positive drive torque to the transmission input shaft.

[0026] If necessary, the system is configured to cause a non-negative net drive torque to be applied at least partially to the input shaft of the gearbox by causing the electric machine to apply a positive drive torque to the input shaft of the gearbox.

[0027] If necessary, the system is configured to command the application of braking torque by the second braking device to compensate for the reduction in negative drive torque applied to the transmission input shaft within a specified period before a transmission gear change takes place.

[0028] This feature has the advantage that any delay in the application of braking torque by the second braking device after commands to apply braking torque by the second braking device can be compensated for by commanding the application of braking torque before the gear change takes place.

[0029] Optionally, the system includes an electronic processor with an electrical input for receiving a signal indicating that a gear change is imminent, requiring that a non-negative torque be applied to the input shaft of the transmission, and an electronic storage device electrically coupled to the electronic processor with instructions stored therein. wherein the processor is configured to access the memory device and execute the instructions stored therein, so that it is operational to determine, based on the received signal, when a gear change is imminent that requires the application of a non-negative torque to the transmission input shaft, and, if a negative net drive torque is applied to the transmission input shaft and it is determined that a gear change is imminent that requires the application of a non-negative torque, to temporarily cause a non-negative net drive torque to be applied to the input shaft, and to cause braking force to be applied to one or more wheels of the vehicle by a second braking device to compensate for the reduction of the negative drive torque applied to the transmission input shaft while the transmission gear change is taking place.

[0030] In another aspect of the invention for which protection is claimed, a motor vehicle is provided which includes a control system according to another aspect.

[0031] In one aspect of the invention for which protection is claimed, a method for controlling a vehicle with at least one electric machine configured to cause torque to be applied to an input shaft of a transmission is provided, wherein the method is implemented by a control system and comprises the following: To cause a negative net drive torque to be applied to the input shaft of the transmission in a direction opposite to the direction of travel of the vehicle, at least partially by means of the electric machine, in order to brake; Determine when a gear change is imminent that requires the application of a non-negative torque to the transmission's input shaft; and, If a negative net drive torque is applied to the input shaft of the transmission and it is determined that a gear change is imminent which requires the application of a non-negative torque, temporarily cause a non-negative drive torque to be applied to the input shaft and cause braking force to be applied to one or more wheels of the vehicle by a second braking device to compensate for the reduction of the negative drive torque applied to the input shaft of the transmission while the gear change is taking place.

[0032] The vehicle can be a purely electric vehicle or a hybrid vehicle with a motor, whereby the negative net drive torque is caused by at least one of the motor and the electric machine.

[0033] If necessary, the procedure may include commanding the application of braking torque by the second braking device to compensate for the reduction in negative drive torque applied to the input shaft of the transmission within a specified period before a transmission gear change takes place.

[0034] The procedure may include determining when the gear change will take place, at least partially dependent on information indicating an immediate speed of the transmission and information indicating a speed of the transmission at which a gear change will take place.

[0035] In one aspect of the invention for which protection is claimed, a non-transient computer-readable carrier medium is provided which contains a computer-readable code for controlling a vehicle in order to carry out the method according to another aspect.

[0036] In another aspect of the invention for which protection is claimed, a computer program product executable on a processor is provided to execute the method according to another aspect.

[0037] In one aspect of the invention for which protection is claimed, a computer-readable medium loaded with the computer program product of another aspect is provided.

[0038] In another aspect of the invention for which protection is claimed, a processor is provided which is arranged to execute the method or the computer program product according to another aspect.

[0039] In another aspect of the invention, a control system for a hybrid electric vehicle is provided, comprising a motor and at least one electric machine, each configured to cause torque to be applied to an input shaft of a transmission, wherein the control system is configured to: to cause a negative net drive torque to be applied to the input shaft of the transmission in a direction opposite to the direction of travel of the vehicle, at least partially by means of the electric machine, in order to brake; to determine when a gear change is imminent that requires the application of a non-negative torque to the transmission's input shaft; and If a negative net drive torque is applied to the input shaft of the transmission and it is determined that a gear change is imminent which requires the application of a non-negative torque, to temporarily arrange for a non-negative drive torque to be applied to the input shaft by at least one of the motor and electric machine, and to arrange for braking force to be applied to one or more wheels of the vehicle by a second braking device in order to compensate for the reduction of the negative drive torque applied to the input shaft of the transmission while the transmission gear change is taking place.

[0040] In another aspect of the invention, a method for controlling a hybrid electric vehicle with a motor and at least one electric machine, each configured to cause torque to be applied to an input shaft of a transmission, is provided, the method being executed by a control system and comprising the following: To cause a negative net drive torque to be applied to the input shaft of the transmission in a direction opposite to the direction of travel of the vehicle, at least partially by means of the electric machine, in order to brake; Determine when a gear change is imminent that requires the application of a non-negative torque to the transmission's input shaft; and, If a negative net drive torque is applied to the input shaft of the transmission and it is determined that a gear change is imminent which requires the application of a non-negative torque, to temporarily arrange for a non-negative drive torque to be applied to the input shaft by at least one of the motor and electric machine, and to arrange for braking force to be applied to one or more wheels of the vehicle by a second braking device in order to compensate for the reduction of the negative drive torque applied to the input shaft of the transmission while the transmission gear change is taking place.

[0041] It should be noted that the control unit(s) described herein may each comprise a control unit or a computing device with one or more electronic processors. The system may comprise a single control unit or a single electronic control device, or alternatively, different functions of the control unit may be performed or contained in different control units or devices. The term "control unit," as used herein, is to be understood as including both a single control unit or device and a plurality of control units or devices working together to provide the required control function. A set of instructions may be provided which, when executed, cause the control unit to implement the control techniques described herein. The instructions may be embedded in the one or more processors.Alternatively, the instructions can be provided as software to be executed on the computing device. The speed controller can be implemented in software running on one or more processors. One or more other control devices can be implemented in software running on one or more electronic processors, optionally on the same or more processors as the speed controller. Other arrangements may also be suitable.

[0042] 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 way and / or in any combination, provided that these features are not incompatible.The applicant reserves the right to amend any originally filed patent claim or to file any new patent claim accordingly, including the right to amend any originally filed patent claim to depend on and / or incorporate any feature of any other patent claim, even if it was not previously claimed in this manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Embodiments of the invention will now be described with reference to the accompanying drawings, which show: Fig. 1 a schematic representation of a hybrid electric vehicle according to an embodiment of the present invention; Fig. 2 a schematic representation of a control system according to an embodiment of the present invention; and Fig. 3 a graphical representation of a method according to an embodiment of the invention, wherein the horizontal (x) axis represents the vehicle speed, which increases from left to right (while time increases from right to left), and the vertical (y) axis shows the rate of change of speed (acceleration); and Fig. 4 a schematic representation of a hybrid electric vehicle according to a further embodiment of the present invention. DETAILED DESCRIPTION

[0044] In one embodiment of the present invention, a hybrid electric vehicle 100 is provided, as shown in Fig. 1 shown. The vehicle 100 has an engine 121 and a dedicated starter 121S which is operational to start the engine 121 when it needs to be started.

[0045] The engine 121, in turn, is coupled to a crankshaft-integrated motor / generator (CIMG) 123C by means of a crankshaft 121C and clutch 122. The clutch 122 can also be referred to as a co-coupling 122. The CIMG 123C is also capable of starting the engine 121 as needed.

[0046] The CIMG 123C is integrated into the housing of a transmission 124, which in turn is coupled to a drive system 130 of the vehicle 100 to drive a pair of front wheels 111, 112 and a pair of rear wheels 114, 115 of the vehicle 100. The drive system 130, in combination with the transmission 124, the CIMG 123C, the clutch 122, and the motor 121, can be considered part of a drivetrain 131 of the vehicle 100. The wheels 111, 112, 114, 115, which are arranged to be driven by the drive system 130, can also be considered part of the drivetrain 131. The transmission 124 is controlled by a transmission control unit 141T.

[0047] It should be noted that other arrangements are also expedient. For example, the drive system 130 can be arranged to drive only the pair of front wheels 111, 112 or only the pair of rear wheels 114, 115, or to be switchable between a two-wheel drive mode, in which only the front or rear wheels are driven, and a four-wheel drive mode, in which both the front and rear wheels are driven.

[0048] The CIMG 123C is electrically coupled to a charging storage module 150 (which can also be referred to as an energy storage module 150) containing a battery and an inverter. The module 150 is capable of supplying the CIMG 123C with electrical energy when it is operated as a drive motor. Likewise, the module 150 can receive and store electrical energy generated by the CIMG 123C when it is operated as an electric generator.

[0049] The vehicle 100 has a vehicle control unit 140, which is operational to command a powertrain control unit 141PT to control the motor 121, to switch it on or off, and to generate a required amount of torque. The vehicle control unit 140 is also operational to command the CIMG 123C to apply a required value of positive or negative torque (when operating as a drive motor or as a generator) to the drive system 130 via the transmission 124.

[0050] The vehicle has an accelerator pedal 171 and a brake pedal 172. The accelerator pedal 171 provides an output signal to the vehicle control unit 140, indicating the pedal's travel. The vehicle control unit 140 is configured to determine the amount of torque requested by the driver based on the accelerator pedal position and one or more other vehicle parameters, including the engine speed W. In some embodiments, the powertrain control unit 141PT is configured to receive the accelerator pedal position signal and calculate the amount of torque requested by the driver.

[0051] The vehicle 100 from Fig. 1 is operational in an electric vehicle (EV) mode via the vehicle control unit 140, in which the clutch 122 is open and the crankshaft 121C is essentially stationary. In EV mode, the CIMG 123C is operational to apply positive or negative torque to the drive system 130 via the transmission 124. Negative torque can be applied, for example, when regenerative braking is required under the control of a brake actuator 142B.

[0052] The powertrain 131 is capable of operating in one of a variety of parallel modes, in which the engine 121 is engaged and the clutch 122 is engaged. The parallel modes include a "parallel boost" mode, in which the CIMG 123C operates as a motor to provide drive torque to the drive system 130 in addition to the torque supplied by the engine 121. In the present embodiment, the powertrain 131 operates in the parallel boost configuration when the amount of torque requested by the driver exceeds the maximum torque available from the engine 121. The amount of additional torque available from the CIMG 123C can be determined depending on the vehicle configuration, as described in more detail below. It should be noted that the torque boost feature increases the available drive torque beyond that available from the engine 121 alone.

[0053] The parallel operating modes also include a parallel torque-fill mode and a parallel torque-assist mode. The parallel torque-fill mode is a mode in which the CIMG 123C supplies drive torque to the drive unit 130 in addition to the motor 121, in order to meet the driver's torque demand more quickly than if the motor 121 alone were supplying drive torque. Torque filling offers the advantage of allowing the driver's torque demand to be met more quickly, which improves the vehicle's responsiveness to an increase in torque demand, as the CIMG 123C is typically able to respond to torque demands more quickly than the motor 121.

[0054] In the present embodiment, torque filling occurs when the rate of increase of the torque demand from the driver exceeds a prescribed value relative to the amount of torque supplied by the engine 121. Once the torque demand from the driver has been met, the amount of torque supplied by the CIMG 123C decreases, while the amount of torque supplied by the engine 121 increases to substantially fully satisfy the driver's demand without requiring any additional torque from the CIMG 123C.

[0055] In parallel torque support mode, the CIMG 123C provides stationary drive torque in addition to the motor 121 to relieve the motor 121. This can contribute to reduced fuel consumption. Torque support can be understood as distinct from "torque filling," the latter being used temporarily when an increase in drive torque is required.

[0056] The drive train 131 can alternatively be operated in a parallel charging mode, in which the CIMG 123C is driven as a generator by the motor 121 to charge the charging storage module 150.

[0057] Vehicle 100 has a hybrid mode selector 145 in the form of a rotary dial. The selector 145 is functional to select one of three hybrid modes: an EV mode, a hybrid mode, and a hybrid lock mode.

[0058] In EV mode, the control unit 140 instructs the motor 121 to remain switched off, while drive torque is supplied as needed only by means of the CIMG 123C. As soon as the charge level of the charging storage module 150 falls below a predetermined value, for example below 10% of a maximum usable charging capacity, the control unit 140 instructs the motor 121 to switch on again and the powertrain 131 to assume the parallel charging mode until the charge level exceeds a predetermined value, for example 25% of a maximum usable charging capacity.

[0059] In hybrid mode, the control unit 140 directs the powertrain 131 to adopt a parallel mode or EV mode, depending on an energy management methodology (also referred to as a strategy) executed by the control unit 140. Further details of the energy management methodology can be found in GB2483371. The control unit 140 attempts to balance the use of the charge stored in the charge storage module 150 to operate the CIMG 123C as a drive motor and the combustion of fuel by the engine 121 to reduce the emission of greenhouse gases such as carbon dioxide. In some embodiments, other energy management methodologies may be appropriate.

[0060] In hybrid locking mode, the control unit 140 locks the motor 121 in the switched-on state and the co-clutch 122 in the closed state, causing the motor 121 to drive the transmission 124 essentially continuously while the transmission 124 is in a driving mode in which drive torque can be supplied from the transmission 124 to the wheels 111, 112, 114, 115.

[0061] Brake control 142B is operational to initiate a friction-based service brake system, causing each of the wheels 111, 112, 114, and 115 to brake. Brake control 142B is also operational to command the powertrain control unit 141PT to cause the CIMG 123C to act as a generator and apply negative torque to the drive system 130 to initiate braking. This can be referred to as regenerative braking, since the charge generated by the CIMG 123C during braking can be stored in the charge storage module 150.

[0062] The transmission 124 is configured such that, when a gear change occurs between certain gears—in the present embodiment, a gear change from forward gear 8 to a lower forward gear such as forward gear 7, or a change from gear 5 to gear 4—a non-negative net amount of torque must be present at the input shaft of the transmission 124. That is, the amount of torque must be essentially zero or positive. This is because an engaging clutch, similar to a dog clutch, must be engaged as part of the gear change.

[0063] In conventional non-HEV vehicles that do not employ regenerative braking, or in vehicles where regenerative braking occurs at a point in the drivetrain downstream of the transmission 124 with respect to a torque transmission path from the motor 121 to the wheels 111, 112, 114, 115, the motor 121 is the only drive unit coupled to the input shaft of the transmission 124. The amount of negative torque exerted on the transmission 124 by the motor 121 when the accelerator pedal is released and the vehicle 100 decelerates from a speed higher than the creep speed is small enough to cause the motor 121 to exert non-negative torque relatively quickly and temporarily from the powertrain control unit 141PT on the transmission 124 while the gear change takes place.This can be achieved, for example, by automatically providing temporary fuel to the engine and starting the temporary fuel supply immediately before the gear change takes place.

[0064] In contrast, in embodiments of the present invention, the amount of negative torque exerted on the transmission 124 by the motor 121, in combination with that exerted by the CIMG 123C during regenerative braking, is relatively large. Temporarily removing this negative torque, which would result in a non-negative amount of torque being exerted on the transmission 124, would cause an unacceptably strong jolt to the vehicle 100.

[0065] For example, the amount of engine braking torque developed by the 121 engine upon releasing the accelerator pedal can be relatively low, around -20 Nm in some vehicles. When a gear change occurs in a non-hybrid vehicle with such a transmission, the 121 engine may be temporarily caused to develop an additional 20 Nm of torque, resulting in the net torque of the engine output shaft essentially dropping to zero. Such a torque increase is relatively small and typically does not cause an unacceptable jerk in the 100. However, it is desirable to operate the CIMG 123C in such a way that a negative torque level of approximately -70 to -80 Nm is exerted after the accelerator pedal is released. Reducing this amount of torque to essentially zero within a relatively short period would result in an unacceptable jerk intensity, i.e., rate of change of acceleration.

[0066] To facilitate the provision of a non-negative amount of torque at the input to the transmission input shaft 124IN during a gear change requiring a non-negative amount of torque, the control unit 140 is configured to detect when such a gear change is imminent. The control unit 140 then causes the CIMG 123C to generate an amount of positive torque (instead of negative torque) sufficient to compensate for the negative torque exerted by the motor 121, such that the net torque exerted on the transmission input shaft 124IN is essentially zero. In some embodiments, the control unit causes the amount of torque exerted by the CIMG 123C to be high enough so that the net torque exerted on the transmission input shaft 124IN is substantially greater than zero.In some embodiments, the amount of torque exerted by the CIMG 123C is essentially reduced to zero, and the fuel supply to the engine 121 is sufficient to also essentially reduce the amount of overrun braking torque to zero.

[0067] Control unit 140 also instructs brake control unit 142B to command the service brake system to apply braking force to wheels 111, 112, 114, and 115 in order to compensate for the reduction in the negative torque applied to the transmission input shaft 124IN. Brake control unit 142B attempts to ensure that the braking torque is applied in such a way that the vehicle 100 continues to decelerate at essentially the same rate as before the gear change, with the driver experiencing little or no jerk due to the change in net torque at input shaft 124IN. Thus, it should be noted that the service brake system is used to compensate for the reduction in the amount of negative torque applied by CIMG 123C.

[0068] Fig. Figure 2 is a schematic representation of how the vehicle control unit 140 controls the powertrain control unit 141PT and the brake control unit 142B to achieve this.

[0069] The vehicle control unit 140 receives the following signals: (a) Accelerator pedal position signal 1; (b) Vehicle reference speed signal 2, corresponding to the vehicle speed over ground; (c) CIMG 123C Speed ​​signal 3; (d) Gearbox output shaft speed signal 4; (e) Transmission output shaft shift point signal 5, corresponding to the transmission output speed at which a gear change is triggered; (f) An actual gear position signal 6 indicating the gear in which the transmission 124 is currently operating; (g) A target gear position signal 7 indicating the gear into which the transmission 124 should shift; (h) A gear change status signal 9 indicating whether a gear change is currently taking place.

[0070] In some embodiments, the control unit 140 also receives a drive system ratio signal 8 indicating the currently selected drive system ratio; in the present embodiment, this ratio is fixed, since a switchable drive system gearbox with high / low ratio is not provided and this signal is not supplied. Thus, section A of Fig. 2 (described below) is not provided in the present embodiment.

[0071] It should be noted that methods for calculating the vehicle reference speed signal 2 are well known in the art and include, for example, setting the reference speed signal 2 to the speed of the second slowest rotating wheel. In some embodiments, other methods for generating a vehicle reference speed signal 2 may be advantageous.

[0072] The control unit 140 implements computer code that performs various functions. For the sake of clarity, these functions are described as "function blocks." Referring to the functions as "blocks" should in no way be interpreted as restricting the manner in which the functionality is executed. In some embodiments, one or more functions can be implemented analogously by separate components instead of using computer code.

[0073] With reference to Fig. Function block B101 receives the accelerator pedal position signal 1 and applies the signal 1 to a torque request diagram to obtain a drivetrain torque value corresponding to the signal 1. In some embodiments, block B101 can take into account one or more additional parameters, such as engine speed, for example, based on an engine speed signal or CIMG speed signal 3, which is essentially equal to the engine speed when the clutch Ko is engaged. Block B101 outputs the drivetrain torque value to a summing function block S101.

[0074] Function block B103 applies an accelerator pedal scaling function to the accelerator pedal position signal 1 and generates a scaled accelerator pedal position signal 1S. The scaled pedal signal 1S is applied to a multiplier function block M101.

[0075] The vehicle reference speed signal 2 and the CIMG speed signal 3 are applied to an overrun torque calculation function block B105, which is computer code that calculates a base value of required overrun torque, Base_Overrun_Tq, based on a target deceleration value as a function of vehicle speed when the accelerator pedal is in a fully released position. Overrun torque refers to the amount of negative torque exerted on the transmission input shaft 124IN by the motor 121 and CIMG 123C in combination. The value of Base_Overrun_Tq is applied to a multiplier function block M103.

[0076] The transmission output speed signal 4, the transmission output shaft shift point signal 5, the actual gear position signal 6, indicating the gear in which the transmission 124 is currently operating, the target gear position signal 7, indicating the gear into which the transmission 124 is to shift, and the gear shift status signal 9 are applied to a dog clutch shift detection function block B107. Function block B107 is configured to determine when a "torque-critical" gear shift involving the operation of a dog clutch of the transmission 124 is to take place, requiring non-negative drive torque to be applied to the input shaft 124IN of the transmission 124. Function block B107 sets an output signal to "TRUE" at a predetermined time before the start of the gear shift.In the present embodiment, the specified period is 350 ms, although other periods such as 250 ms, 500 ms, or any other suitable value may be expedient in some embodiments. The output signal is transmitted to a brake release factor function block B109.

[0077] It should be noted that function block B107 calculates the time before a torque-critical gear change is likely to occur, based on the rate of change of the transmission output shaft speed, which is calculated from the transmission output shaft speed signal 4 and the transmission output shaft shift point signal 5. Function block B107 determines the time that will likely elapse before the transmission output shaft speed becomes substantially equal to the speed at which the gear change will occur. Function block B107 then sets its output to TRUE during the period in which the duration of this time is less than or equal to 350 ms, as noted above.Once the output of function block B107 is set to TRUE, the brake release begins, with the brake release factor function block B109 outputting a signal that transitions from 0 to 1 in steps of 0.1 over the predetermined time period, which in this embodiment is 350 ms, as noted above. Thus, the signal transitions in 35 ms steps at a rate of 1 step every 0.1 s.

[0078] In some alternative embodiments, the transmission control unit 141T can be configured to predict when a torque-critical gear change will occur and transmit a signal to the powertrain control unit 141PT indicating that such a gear change will occur within a predetermined time interval, essentially from the moment the signal is transmitted. The predetermined time interval can be any suitable interval, such as 250 ms, 350 ms, 500 ms, or any other suitable interval. The control unit 140 can initiate the transition to the application of non-negative drive torque at the transmission input shaft 124IN and the corresponding application of compensating service braking when the transmission control unit 141T transmits the signal to the powertrain control unit 141PT indicating that such a torque-critical gear change will occur within the predetermined time interval.

[0079] In further embodiments, the transmission control unit 141T can be configured to output a probability signal indicating when a torque-critical gear change will occur. The probability signal can indicate the probability of shifting from essentially zero at a predetermined time before the shift begins, changing to indicate a probability of shifting from essentially 1 as the shift point approaches. The transition to the application of non-negative torque to the transmission input shaft 124IN, with corresponding application of compensating service braking, can occur while the probability signal changes from 0 to 1 analogously to that at which the transition occurs in response to the output of the brake release factor function block B109 in the present embodiment.

[0080] In some embodiments, other arrangements may be expedient.

[0081] With reference to Fig. 2. The summing function block S103 receives the output of the brake release factor function block B109 at a subtraction input thereof and a corresponding '1' signal at a summing input thereof. The summing function block S103 outputs a signal to the multiplier function block M103 that corresponds to the difference between the input signals at the summing and subtraction inputs. The multiplier function block M103, in turn, multiplies the input signals and outputs the product of the signals to the multiplier function block M101. The multiplier function block M101, in turn, multiplies the input signals and outputs the product of the signals to the summing function block S101. In some embodiments where the vehicle 100 is equipped with a high / low ratio transmission in addition to the transmission 124, section A from Fig. 2. That is, the output signal of the multiplier function block M101 is provided to a crankshaft torque conversion function block B111, which also receives a signal 8 indicating the currently selected gear ratio of the high / low transmission. The output of the crankshaft torque conversion function block B111 depends on signal 8 as well as on the signal received from multiplier function block M101 and enables the control unit 140 to compensate for changes in wheel torque for a given transmission output shaft torque due to the high / low transmission setting.

[0082] The summing function block S101 receives the output signal generated by function block B101 at a summing input and the output signal generated by multiplier function block M101 at a subtraction input. The output of summing function block S101, which corresponds to the difference between the input signals, is fed to a temporary powertrain torque shaping function block B113, which outputs a powertrain torque request signal 10 to the powertrain control unit 140PT.

[0083] It should be noted that the control unit 140 is configured such that blocks S103, M103 and M105 are arranged to cause the powertrain overrun torque to be hidden and braking torque supplied by the service brake system to be shown, while the output of the brake release factor function block B109 changes from 0 to 1.

[0084] The output of multiplier function block M105, together with that of function block B103, is fed to multiplier function block M107. The product of the signals is then fed to the temporary brake torque shaping function block B115, whose output is forwarded to the brake control unit 142B in the form of a brake torque request signal 12.

[0085] The temporary powertrain torque function block B113 and the temporary brake torque shaping function block B115 are arranged to compensate for the various temporary responses of the powertrain (which supplies torque through the motor 121 and CIMG 123C) and the braking system. Blocks B113 and B115 ensure that the net amount of torque delivered to the driven wheels 111, 112, 114, and 115 remains substantially unchanged during the brake release period.

[0086] Once the gear change has occurred, the output of function block B107 is set to FALSE and the brake release factor function block B109 generates an output signal that changes from '1' to '0' over a predetermined period, 350 ms in the present embodiment. During this period, the amount of braking force generated by the braking system is reduced, while the amount of negative torque generated by the drivetrain is increased to essentially restore regenerative braking to the state it was in before the gear change began.

[0087] In the present embodiment, the completion of a gear change is detected depending on a signal generated by the transmission control unit 140T, which indicates that the gear change has been completed.

[0088] In some embodiments, the powertrain control unit 140PT monitors the "torque high" intervention (i.e., the change in powertrain output torque to prevent negative drive torque from being applied to the transmission input shaft 124IN) and determines that the gear change is complete when "speed high" is removed. The powertrain control unit 140PT can output a signal indicating that the "torque high" intervention has ended, allowing one or more functions that need to be aware of this to respond accordingly.

[0089] Fig. Figure 3 graphically illustrates aspects of the operation of the control unit 140 described above. The horizontal (x-)axis consists of Fig. Figure 3 represents the vehicle speed, which increases from left to right. Since the present invention relates to the vehicle control unit during braking, it should be noted that the sequence of the steps shown in Figure 3 is not the same as the sequence shown in Figure 3. Fig. The three events depicted (from left to right) take place while the vehicle speed decreases, i.e., time passes from right to left. Fig. 3, as indicated by the "time" arrow below the x-axis. The vertical (y-)axis shows the rate of change of velocity (acceleration) from top to bottom in the diagram. Fig. 3 becomes increasingly negative.

[0090] Line T1 shows the rate of change of the speed traversed by vehicle 100 (which is negative in the figure because vehicle 100 is decelerating) during the deceleration of vehicle 100 when a gear change occurs, requiring a non-negative drive torque at the transmission input shaft 124IN. It can be seen that the rate of deceleration is essentially constant during the braking period, including the time during which the gear change takes place. The speed range (and thus the relative time) in which the gear change occurs in the illustrated example is shown by line T2, where the gear change begins at time 11 and ends at time t2, with respect to an arbitrary time axis that is not necessarily linear in the figure (which is linear with speed, but the rate of deceleration of vehicle 100 fluctuates, as shown by line T1).

[0091] In contrast, line T3 shows the rate of change of speed that the vehicle would go through at 100 if the control unit 140 were not configured to apply the service braking system to compensate for the decrease in the rate of deceleration (to less negative values ​​of the rate of change of speed, possibly essentially to zero or positive values ​​of the rate of change of speed, i.e., positive acceleration) when a "torque up" intervention occurs. A significant decrease in the rate of deceleration can be observed immediately before the gear change when the "torque up" operation takes place.

[0092] Line T4 schematically illustrates how the amount of negative torque generated by the engine 121 and CIMG 123C is reduced by the control unit 140 by transmitting appropriate signals to the powertrain control unit 141PT before the gear change, with the vertical (y) axis representing the amount of torque (which becomes increasingly negative from top to bottom in the direction of arrow A). Line T5 schematically illustrates how the amount of negative torque generated by the braking system is caused to increase before the gear change, with the vertical (y) axis representing the amount of braking torque, which becomes increasingly negative from top to bottom in the direction of arrow B.It can be seen that the amount of braking torque exerted by the braking system is increased ("ramped up"), while the amount of negative drive torque exerted by the engine 121 and CIMG 123C is reduced (dash T4). This brake torque and negative drive torque separation is carried out to ensure that the deceleration rate of the vehicle 100 remains essentially constant during gear changes, as shown by dash T1.

[0093] In some alternative embodiments, the vehicle may have a belt-driven starter / generator (BISG) instead of a CIMG 123C. Fig. Figure 4 shows a "mild" hybrid electric vehicle 200 according to an embodiment with a BISG 223B instead of a CIMG 123C. The embodiment has the same features as shown in Figure 4. Fig. 4 such as those of the embodiment from Fig. 1 are shown with the same reference symbols, increased by 100.

[0094] In the embodiment from Fig. 4. The vehicle control unit 240 controls the vehicle 200 in a similar way to the control unit 140. Fig. 1, except that the BISG 223B is substantially permanently coupled to and rotates with the motor 221 and is configured to apply positive, negative, or substantially zero torque to the motor 221 under the control of the powertrain control unit 241PT. The powertrain control unit 241PT, in turn, is controlled at least partially by the vehicle control unit 240. The powertrain control unit 241PT is configured so that the motor 221 and the BISG 223B can provide coasting braking, such that the BISG 223B provides regenerative braking to discharge the charge storage module 250 in a manner similar to that used in the vehicle 100. Fig. 1 to recharge.

[0095] Embodiments of the present invention enable the implementation of a regenerative coasting braking function, wherein an electric machine is arranged to provide coasting braking when an accelerator pedal is released, even in vehicles with a transmission that requires non-negative torque at one of its inputs during certain gear changes. This is because vehicles according to embodiments of the present invention compensate for the need for non-negative torque by providing non-negative torque at the transmission input during certain gear changes, while compensating for the associated change in drivetrain torque by applying braking torque, such that a substantially constant amount of negative drivetrain torque is provided during the period immediately before, during, and immediately after the gear change.As noted above, the braking torque can be provided by a friction-based service braking system or any other suitable braking device, such as an electric machine, downstream of the transmission in a torque path from the transmission to one or more wheels. Such an electric machine may, for example, be encompassed by an axle of the vehicle, such as a rear axle, as in an electric rear-wheel drive (ERAD) arrangement, or by means of wheel-hub-mounted electric machines, or the like. In some embodiments, other arrangements may be advantageous.

[0096] Although certain embodiments of the invention have been described above in the form of a hybrid electric vehicle, it should be noted that the techniques described herein are equally applicable to a pure electric vehicle that does not use a motor but relies solely on electric motors to provide torque.

[0097] Throughout the description and claims of this patent specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "includes", mean "including but not limited to" and are not intended to exclude (and do not exclude) any other units, additives, components, integers or steps.

[0098] Throughout the entire description and the claims of these patent applications, the singular includes the plural unless the context requires otherwise. In particular, where the indefinite article is used, the patent specification should be understood to include both plurality and singularity unless the context requires otherwise.

[0099] Features, integers, characteristics, compounds, chemical components or groups described in connection with a particular aspect, embodiment or example of the invention are to be understood as applicable to any other aspect, embodiment or example described herein, provided they are not incompatible with it.

Claims

[1] Control system (140, 240) for a hybrid vehicle (100) with an engine (121, 221) and at least one electric machine (123C), each configured to cause torque to be applied to an input shaft (124IN) of a transmission (124), wherein the control system (140, 240) is configured to: to cause a negative net drive torque to be applied to the input shaft (124IN) of the gearbox (124) in a direction opposite to the direction of travel of the vehicle (100), using the motor (121, 221) and the electric machine (123C), in order to brake; to determine when a gear change is imminent that requires the application of a non-negative torque to the input shaft (124IN) of the transmission (124); and, If a negative net drive torque is applied to the input shaft (124IN) of the transmission (124) and it is determined that a gear change is imminent which requires the application of a non-negative torque, a non-negative net drive torque is temporarily applied to the input shaft (124IN) by causing the electric machine (123C) to apply a positive torque to the input shaft (124IN) of the transmission (124) sufficient to compensate for the negative torque applied by the motor (121, 221), and braking force is applied to one or more wheels (111, 112, 114, 115) of the vehicle (100) by a second braking device to compensate for the reduction of the negative drive torque applied to the input shaft (124IN) of the transmission (124) during the gear change. [2] System (140, 240) according to claim 1, which is configured to receive a drive request signal indicating an amount of required drive torque of a drive train (131) of the vehicle (100), wherein the system (140, 240) is configured to cause negative drive torque to be exerted at least partially by the electric machine (123C) in at least partial dependence on the drive request signal. [3] System (140, 240) according to one of the preceding claims, which is configured to receive a brake force request signal indicating an amount of brake force required, wherein the system (140, 240) is configured to cause negative drive torque to be exerted at least partially by the electric machine (123C) in at least partial dependence on the brake force request signal. [4] System (140, 240) according to one of the preceding claims, which is configured to command the application of braking torque by the second braking device to compensate for the reduction in negative drive torque applied to the input shaft (124IN) of the transmission (124) in a predetermined period of time before a transmission gear change takes place. [5] System (140, 240) according to one of the preceding claims, comprising an electronic processor with an electrical input for receiving a signal indicating that a gear change is imminent which requires that a non-negative torque be applied to the input shaft (124IN) of the transmission (124), and an electronic storage device electrically coupled to the electronic processor with instructions stored therein, wherein the processor is configured to access the storage device and execute the instructions stored therein, such that it is operational to determine, based on the received signal, when a gear change is imminent which requires the application of a non-negative torque to the input shaft (124IN) of the transmission (124), and, when a negative net drive torque is applied to the input shaft (124IN) of the transmission (124) and is detected,that a gear change is imminent which requires the application of a non-negative torque, to temporarily cause a non-negative net drive torque to be applied to the input shaft (124IN) by causing the electric machine (123C) to apply a positive drive torque to the input shaft (124IN) of the transmission (124) sufficient to compensate for the negative torque applied by the motor (121, 221), and to cause braking force to be applied to one or more wheels (111, 112, 114, 115) of the vehicle (100) by a second braking device to compensate for the reduction of the negative drive torque applied to the input shaft (124IN) of the transmission (124) while the gear change is taking place. [6] Hybrid motor vehicle (100) comprising a control system (140, 240) according to any of the preceding claims. [7] Method for controlling a hybrid vehicle (100) with an engine (121, 221) and at least one electric machine (123C), each configured to cause torque to be applied to an input shaft (124IN) of a transmission (124), wherein the method is performed by a control system (140, 240) and comprises: To cause a negative net drive torque to be applied to the input shaft (124IN) of the gearbox (124) in a direction opposite to the direction of travel of the vehicle (100), using the motor (121, 221) and the electric machine (123C), in order to brake; Determine when a gear change is imminent that requires the application of a non-negative torque to the input shaft (124IN) of the transmission (124); and, If a negative net drive torque is applied to the input shaft (124IN) of the transmission (124) and it is determined that a gear change is imminent which requires the application of a non-negative torque, to temporarily cause a non-negative drive torque to be applied to the input shaft (124IN) by causing the electric machine (123C) to apply positive torque to the input shaft (124IN) of the transmission (124), and to cause braking force to be applied to one or more wheels (111, 112, 114, 115) of the vehicle (100) by a second braking device to compensate for the reduction of the negative drive torque applied to the input shaft (124IN) of the transmission (124) while the transmission gear change is taking place. [8] Method according to claim 7, which includes commanding the application of braking torque by the second braking device to compensate for the reduction in negative drive torque applied to the input shaft (124IN) of the transmission (124) in a predetermined period of time before a transmission gear change takes place. [9] Method according to claim 8, which comprises determining when the gear change will take place, at least partially depending on information indicating an immediate speed of the transmission (124) and information indicating a speed of the transmission (124) at which a gear change will take place. [10] Non-transient computer-readable carrier medium containing a computer-readable code for controlling a vehicle (100) to perform the method according to any one of claims 7 to 9. [11] A computer program product executable on a processor for performing the method according to any one of claims 7 to 9. [12] Computer-readable medium loaded with the computer program product according to claim 11. [13] Processor arranged to execute the method according to any one of claims 7 to 9 or the computer program product according to claim 12.

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