Selection strategy for operating a hybrid engine to avoid noise problems

Abstract

Method for controlling a hybrid powertrain (100) comprising a power unit (14), an electric motor (56, 72) and a transmission (10) to avoid a problem of noise, vibration and roughness related to backlash in the transmission (10), which is referred to as growling, the method comprising: Monitoring the operation of the powertrain (100); wherein the conditions necessary for growling to occur include that the motor torque (420) of the electric motor (56, 72) is lower than a threshold motor torque (424, 422); that the torque (404; 804; 904; 1204) of the power machine (14) is greater than a threshold torque (430; 630) of the power machine (14); that the output speed of the transmission (10) is between an identified minimum speed of the output shaft (64) and an identified maximum speed of the output shaft (64); and that clutches (70, 62, 73, 75) in the transmission (10) are engaged in a clutch state that leads to growling (1104); wherein, in a domain of torque of the power engine (404; 504, 604; 704; 804; 904; 1204) to output torque (402; 502; 602; 702; 802; 902; 1202), the operating range (440; 540; 640, 642; 740, 742; 840, 842; 940, 942; 1240, 1242) of the drive train (100), in which growling is enabled, is determined on the basis of the threshold engine torque (424, 422) and is based on the threshold torque (430; 530) of the power engine (1106); when the conditions that can lead to growling are present and an initial operating point (805; 909) of the electric motor (56, 72) must be transitioned to a target operating point (809; 905), whereby the transition cannot be achieved by solely changing the operating point of the electric motor (56, 72) without passing through the range (840, 842; 940, 942) in which growling can occur, Controlling the powertrain (100) based on avoiding the operating range (840, 842; 940, 942) of the powertrain (100) in which growling is enabled, wherein controlling the powertrain (100) comprises: Monitoring an initial operating point (805; 909) of the powertrain (100); Monitoring a target operating point (809; 905) of the powertrain (100); Determining a transition point (843) to move the drive train (100) from the initial operating point (805; 909) to the target operating point (809; 905) while remaining outside the operating range (840, 842; 940, 942) of the drive train (100) in which growling is enabled; and Controlling a transition of the drive train (100) from the initial operating point (805; 909) to the target operating point (809; 905) on the basis of the transition point (843), wherein the torque of the power machine (14) during the transition falls below the threshold torque (430; 630) of the power machine (14) (1108).

Description

[0001] This disclosure concerns noise, vibration, and harshness issues in a hybrid drivetrain.

[0002] Powertrain systems may be configured to transfer torque originating from multiple torque-generating devices through a transmission device to an output member, which may be coupled to a driveline. Such powertrain systems include hybrid powertrain systems and electric vehicle powertrain systems. Control systems for operating such powertrain systems may operate the torque-generating devices and apply torque-transmitting components in the transmission to transfer torque in response to operator-commanded output torque requests, taking into account fuel economy, emissions, drivability, and other factors. Example torque-generating devices include internal combustion engines and non-combustion torque machines.The non-combustion torque machines may include electric machines that can operate as motors or generators to produce torque input to the transmission independent of torque input from the internal combustion engine. The torque machines may convert vehicle kinetic energy transferred through the vehicle driveline into electrical energy storable in an electrical energy storage device. A control system monitors various inputs from the vehicle and the operator and provides functional control of the powertrain, including controlling transmission operating state and gear shifting, controlling torque-producing devices, and regulating the exchange of electrical power between the electrical energy storage device and the electric machines to manage transmission outputs, including torque and speed.

[0003] DE 10 2010 026 982 A1 teaches a method for operating a hybrid powertrain system in conjunction with audible noise for a hybrid powertrain system. The method includes monitoring operation of the torque machine and limiting the engine torque output from the torque machine to a maximum allowable engine torque associated with an acceptable audible noise level when the engine speed of the torque machine is within an engine speed range associated with disturbing audible noise.

[0004] DE 11 2011 104 902 T5 discloses a drive control device for a hybrid vehicle driven via a powertrain using the power of an engine and the power of a motor that can be operated with power supplied by a battery. The drive control device is intended to prevent vehicle vibrations due to torque ripple at engine speeds close to zero. The drive control device includes a drive control function configured to correct an engine operating point target defined by an engine speed target and an engine torque target such that, when the engine speed comes within a prohibition range of engine operation, which is a predetermined range close to 0 rpm of the engine speed, while the vehicle is driven under control of operating conditions of the engine and the engine, the engine speed is outside the range.

[0005] A method for preventing transmission noise is known from DE 10 2007 000 331 A1. When a demand exists to start or stop an engine, it is determined whether the front drive torque is within a torque range that generates transmission noise. If it is determined that the front drive torque is within the torque range that generates transmission noise, the torque distribution between the front and rear wheels is changed so that the front drive torque is no longer within the torque range that generates transmission noise. Furthermore, the front drive torque is increased when the torque of a motor / generator is increased.Accordingly, generation of transmission noise due to the front drive torque becoming equal to or less than zero is prevented in a transmission mechanism regardless of a relatively large torque fluctuation when the engine is started or stopped.

[0006] DE 10 2007 055 727 A1 discloses a control device for a vehicle drive device having an engine and a motor. The control device suppresses the occurrence of engine noise and / or transmission noise when determining the engine operating point and the engine operating point. When the engine operating point, which is determined based on the system efficiency, is located in a noise-generating region, a noise-generating region avoidance device changes the engine operating point and the engine operating point so that the engine operating point avoids the noise-generating region. Therefore, it is possible to suppress the occurrence of noise that is noticeable at the specific engine operating point.

[0007] It is the object of the invention to provide an alternative method for controlling a hybrid powertrain comprising an engine, an electric motor and a transmission to avoid a problem of noise, vibration and harshness, referred to as growl, related to play in a transmission.

[0008] This object is achieved by a method having the features of claim 1.

[0009] Advantageous embodiments are specified in the dependent claims.

[0010] The invention is described below by way of example with reference to the drawings, in which Fig. 1 illustrates a powertrain system including an internal combustion engine, a multi-mode electromechanical transmission, a driveline, and a controller, according to the present disclosure; Fig.2 illustrates data from an exemplary powertrain illustrated in an engine torque to output torque domain, illustrating regions where output torque growl is possible and not possible, in accordance with the present disclosure; Fig. 3 illustrates data for an exemplary engine showing an acceptable relationship between engine speed and engine torque, wherein zero to peak torque oscillations generated from combustion at operating points are not large enough to cause growling, regardless of the operating points of the other torque-producing machines, in accordance with the present disclosure; Fig.4 illustrates data from an exemplary powertrain in a domain from engine torque to output torque, illustrating regions where near-zero output torque growl is and is not possible, including a maximum engine torque value below which growl is not possible, in accordance with the present disclosure; Fig. 5 illustrates data from an exemplary powertrain in a domain of engine torque to output torque, illustrating a defined allowable operating range where near-zero output torque growl is possible and not possible, and operation at an exemplary operating point with an engine operating alone to serve an accessory / cargo load, in accordance with the present disclosure; Fig. 6 the operating point of Fig.5, including the permissible operating range of Fig. 5 with an extended range of impermissible operation corresponding to the operating point, according to the present disclosure; Fig. 7 the auxiliary unit charging operation with the engine switched on, including the operating point of Fig. 5 illustrates engine-off operation and transitions therebetween in accordance with the present disclosure; Fig. 8 the auxiliary unit charging operation with the engine switched on, including the operating point of Fig. 5, and illustrates a transition to a second operating point at which the transmission transmits torque corresponding to an output torque, according to the present disclosure; Fig. 9 the transition from Fig. 8 in reverse gear according to the present disclosure; Fig.10 illustrates lines of constant battery power as they relate to operating points in an engine torque / output torque domain, according to the present disclosure; and Fig. 11 illustrates an exemplary process according to the present disclosure.

[0011] Fig. 1 illustrates a powertrain system including an internal combustion engine, an electromechanical multi-mode transmission, a final drive, and a controller. Fig.1 shows a multi-mode powertrain system 100 including an internal combustion engine (engine) 14, a multi-mode transmission (transmission) 10, a driveline 90, and a controller 5. The transmission 10 is mechanically coupled to the engine 14 and includes first and second torque machines 56 and 72, which in one embodiment are electric motor / generators. The engine 14 and the first and second torque machines 56 and 72 each generate torque that can be transferred to the driveline 90 via the transmission 10.

[0012] The exemplary engine 14 is a multi-cylinder internal combustion engine selectively operable in multiple states to transmit torque to the transmission 10 via an input member 12, and may be a spark-ignition or compression-ignition internal combustion engine. The engine 14 includes a crankshaft operatively coupled to the input member 12 of the transmission 10. A speed sensor 11 monitors the speed of the input member 12. Power output by the engine 14, i.e., engine speed and torque, may differ from the input speed and torque to the transmission 10 due to the placement of torque-consuming components on the input member 12 between the engine 14 and the transmission 10, e.g., a torque management device.

[0013] The illustrated transmission 10 is a two-mode, compound power-split electromechanical transmission including three planetary gear sets 24, 26, and 28 and four engageable torque-transmitting devices, i.e., clutches C1 70, C2 62, C3 73, and C4 75. Other multi-mode transmissions may be employed instead. As used herein, clutches refer to torque-transmitting devices that can be selectively engaged in response to a control signal and may be any suitable devices, including, for example, single or compound plate clutches or packs, one-way clutches, band clutches, and brakes. A hydraulic circuit 42 is configured to control clutch states of each of the clutches with pressurized hydraulic fluid supplied by an electrically powered hydraulic pump 17 operatively controlled by the controller 5.Clutches C2 62 and C4 75 are hydraulically engaged rotating friction clutches. Clutches C1 70 and C3 73 are hydraulically controlled braking devices that can be attached to a transmission case 68. Each of clutches C1 70, C2 62, C3 73, and C4 75 is hydraulically engaged using pressurized hydraulic fluid, which in this embodiment is supplied by hydraulic control circuit 42. Hydraulic circuit 42 is functionally controlled by controller 5 to activate and deactivate the aforementioned clutches, provide hydraulic fluid for cooling and lubricating components of the transmission, and provide hydraulic fluid for cooling the first and second torque machines 56 and 72. Hydraulic pressure in hydraulic circuit 42 can be determined by measurement using pressure sensor(s), by estimation using on-board routines, or using other suitable methods.

[0014] The first and second torque machines 56 and 72 are three-phase AC motor / generator machines, each including a stator and a rotor and respective resolvers 80 and 82. The motor stator for each machine is secured to an outer portion of the gear box 68 and includes a stator core with helical electrical windings extending therefrom. The rotor for the first torque machine 56 is supported on a hub plate gear operatively attached to shaft 60 via the second planetary gear set 26. The rotor for the second torque machine 72 is fixedly attached to a hollow shaft hub 66.Each of the resolvers 80 and 82 is signally and operatively connected to a geared power converter control module (TPIM) 19, and each senses and monitors the rotational position of the resolver rotor relative to the resolver stator, thereby monitoring the rotational position of the respective first and second torque machines 56 and 72. Additionally, the signals output by the resolvers 80 and 82 can be used to determine rotational speeds for the first and second torque machines 56 and 72.

[0015] The transmission 10 includes an output member 64, e.g. a shaft, which is rotatably connected to the final drive 90 to provide output power to the final drive 90, which is transmitted to vehicle wheels 93, one of which is in Fig.1. The output power at the output member 64 is characterized in terms of output speed and output torque. A transmission output speed sensor 84 monitors a speed and direction of rotation of the output member 64. Each of the vehicle wheels 93 is preferably equipped with a sensor 94 configured to monitor wheel speed and thus determine vehicle speed and absolute and relative wheel speeds for braking control, traction control, and vehicle acceleration management.

[0016] The input torque from the prime mover 14 and the motor torques from the first and second torque machines 56 and 72 are generated as a result of energy conversion from fuel or electrical potential stored in an electrical energy storage device (ESD) 74. The ESD 74 is high-voltage DC coupled to the TPIM 19 via DC transmission conductors 27. The transmission conductors 27 include a contactor switch 38. When the contactor switch 38 is closed, electrical current can flow between the ESD 74 and the TPIM 19 under normal operation. When the contactor switch 38 is open, electrical current flow between the ESD 74 and the TPIM 19 is interrupted.The TPIM 19 preferably includes a pair of power converters and respective motor control modules configured to receive torque commands and control converter states therefrom, thus providing motor drive or regenerative functionality to meet the motor torque commands. The power converters include complementary three-phase power electronics, and each includes a plurality of insulated-gate bipolar transistors for converting direct current from the ESD 74 into alternating current for driving a respective one of the first and second torque machines 56 and 72 by switching at high frequencies. The insulated-gate bipolar transistors form a switched-mode power supply configured to receive control commands. Each phase of each of the three-phase electric machines includes a pair of insulated-gate bipolar transistors.States of the insulated-gate bipolar transistors are controlled to provide mechanical motor drive power generation or electrical energy recuperation functionality. The three-phase power converters receive or supply DC electrical power via DC transmission conductors 27 and convert it to or from three-phase AC power, which is passed to or from the first and second torque machines 56 and 72 for operation as motors or generators via transmission conductors 29 and 31, respectively.

[0017] The TPIM 19 transfers electrical energy to and from the first and second torque machines 56 and 72 through the pair of power converters and respective motor control modules in response to the motor torque commands. Electrical power is transferred to and from the ESD 74 depending on whether the ESD 74 is charging or discharging.

[0018] The controller 5 is signally and functionally linked to various actuators and sensors in the powertrain system 100 via a communication link 15 to monitor and control the operation of the powertrain system 100, including synthesizing information and inputs and executing routines to control actuators to achieve control objectives related to fuel economy, emissions, performance, drivability, and protection of components, including batteries, ESD 74, and the first and second torque machines 56 and 72. The controller 5 is a subset of an overall control architecture of the vehicle and provides coordinated system control of the powertrain system 100.The controller 5 may comprise a distributed control module system including individual control modules including a supervisory control module, an engine control module, a transmission control module, a battery pack control module, and the TPIM 19. A user interface 13 is preferably signally connected to a plurality of devices through which a vehicle operator directs and commands the operation of the powertrain system 100. The devices preferably include an accelerator pedal 113, an operator brake pedal 112, a transmission range selector 114 (PRNDL), and a vehicle cruise control. The transmission range selector 114 may have a discrete number of operator-selectable positions including the direction of rotation of the output member 64 to enable a forward or reverse direction.The user interface 13 may comprise a single device, as shown, or may alternatively comprise a plurality of user interface devices directly connected to individual control modules.

[0019] The aforementioned control modules communicate with other control modules, sensors, and actuators via communication link 15, which enables structured communication between the various control modules. The particular communication protocol is application-specific. Communication link 15 and appropriate protocols provide robust messaging and interfacing for multiple control modules between the aforementioned control modules and other control modules that provide functionality including, for example, anti-lock braking, traction control, and vehicle stability. Multiple communication buses can be used to improve communication speed and provide a degree of signal redundancy and integrity, including direct connections and serial peripheral interface (SPI) buses.Communication between individual control modules can also be achieved using a wireless connection, e.g., a short-range wireless radio communication bus. Individual devices can also be connected directly.

[0020] Control module, module, control, controller, control unit, processor and similar terms mean any of, or various combinations of, one or more of an application-specific integrated circuit(s) (ASIC), an electronic circuit(s), a central processing unit(s) (preferably a microprocessor(s)) and associated memory and storage (read-only memory, programmable read-only memory, random access memory, hard disk storage, etc.).) that executes one or more software or firmware programs or routines, a combinational logic circuit(s), an input / output circuit and input / output devices, suitable signal conditioning and buffering circuitry, and other components to provide the described functionality. Software, firmware, programs, instructions, routines, code, algorithms, and similar terms mean any set of instructions, including calibrations and lookup tables. The control module has a set of control routines that execute to provide the desired functions.Routines are executed, such as by a central processing unit, and are operable to monitor inputs from sensing devices and other networked control modules, and to execute control and diagnostic routines to manage the operation of actuators. The routines may be executed at regular intervals, for example, every 3.125, 6.25, 12.5, 25, and 100 milliseconds, during ongoing engine and vehicle operation. Alternatively, routines may be executed in response to the occurrence of an event.

[0021] The powertrain system 100 is configured to operate in one of a plurality of states that can be described in terms of engine states including one of an engine-on (ON) state and an engine-off (OFF) state, and transmission ranges including fixed gear modes, variable speed modes (EVT), and neutral modes, as listed in Table 1. Table 1 Description Engine condition Transmission area Actuated clutches M1_Eng_Off OUT OF EVT Mode 1 C1 70 M1_Eng_On A EVT Mode 1 C1 70 G1 A Fixed gear ratio 1 C1 70 C4 75 G2 A Fixed gear ratio 2 C1 70 C2 62 M2_Eng_Off OUT OF EVT Mode 2 C2 62 M2_Eng_On A EVT Mode 2 C2 62 G3 A Fixed gear ratio 3 C2 62 C4 75 G4 A Fixed gear ratio 4 C2 62 C3 73 Neutral ON OFF Neutral -

[0022] The transmission ranges described in Table 1 indicate the specific applied clutch(es) C1 70, C2 62, C3 73, and C4 75 for each of the ranges. For purposes of this description, when the engine OFF state is, the engine input speed is equal to 0 rpm, meaning the engine crankshaft is not rotating. Fixed gear operation provides a fixed ratio of input speed to output speed operation of the transmission 10. In response to operator input via the accelerator pedal 113, the brake pedal 112, and the transmission range selector 114, as sensed by the user interface 13, the control module 5 determines torque commands to control the torque actuators, including the engine 14 and the first and second torque machines 56 and 72, to meet the output torque request at the output member 64 for transmission to the driveline 90.

[0023] Each of the illustrated clutches includes a pair of shafts capable of transmitting reactive torque through the shaft. An engaged clutch can transmit positive torque in a first direction or negative torque in a second direction opposite to the first direction. A condition known as backlash can occur when torque transmitted through the clutch changes from one direction to the other. Under some conditions, backlash is imperceptible to the vehicle's occupants. Under other conditions, backlash creates drivability problems, creating acceleration with noticeable vehicle judder or other drivability degradation or NVH (noise, vibration, and harshness) problems. A particular type of NVH problem related to backlash is known as growl.Under conditions that cause some form of growl, a noticeable rumble may be heard from the transmission. Growl may occur from a locked clutch experiencing backlash. Backlash and / or growl may also occur in gears, planetary gear sets, and any intermeshing metallic components that may have backlash or have components that slap against each other upon reversal of torque. Methods disclosed herein are applied to an exemplary condition involving a locked clutch. However, the examples provided are not intended to be limiting, and similar sets of parameters that allow for backlash in other driveline components may be similarly defined and controlled according to the methods disclosed herein to avoid backlash and associated undesirable driveline conditions, such as growl.

[0024] Through modeling, testing, and / or calibration, conditions that cause growling can be mapped, and ranges of relevant values ​​that lead to growling can be defined. In this way, growling can be reduced or eliminated by avoiding or minimizing operation in growling-inducing ranges.

[0025] Growling can occur in many operating scenarios. Under some conditions, it may not be noticeable or audible. Under other conditions, growling may be masked by high vehicle speeds and associated vehicle NVH conditions. In transmissions similar to the example configuration of Fig. 1, it can be identified that an exemplary growl condition occurs when all of the following five conditions occur simultaneously: 1) the output speed of the gearbox, shaft 64 of the exemplary gearbox of Fig.1) must exist between an identified minimum output shaft speed and an identified maximum output shaft speed; 2) engine speed must exist between an identified minimum engine speed and an identified maximum engine speed; 3) clutches must be engaged in a clutch state that results in growl; 4) engine torque must be above a minimum engine torque that results in growl; and 5) engine torque must fall within a threshold engine torque range, such as embodied by the condition TmMinGrowl < Tm < TmMaxGrowl. According to one embodiment, this range is calibrated to -10 Newton meters (N*m) < Tm < 10 N*m. In an exemplary transmission, growl will be more likely to occur when several of these conditions are present.Other conditions can be identified for other transmissions that may cause growling, and critical ranges of values ​​that lead to growling can be similarly identified for other transmissions.

[0026] Of the five exemplary areas, some of the control parameters can be controlled for the desired operation of the vehicle. For example, for a desired vehicle speed, the transmission and the use of the electric machines can be controlled by Fig.1 to control the engine speed. In this way, the engine speed can be controlled based on the desired operation of the vehicle and on the basis of avoiding the engine speed entering a region where growl is possible or more likely. Similarly, engine torque and motor torques, or torque contributions from each of the torque-generating devices, can be controlled based on avoiding regions where growl is possible or more likely. Other parameters cannot be controlled based on avoiding growl. The output speed is directly related to the vehicle speed. The output torque request is generated by the driver. Any scheme that prevents the vehicle from adopting the operator's desired speed is unlikely to be acceptable.A condition of the clutches in the transmission may or may not be subject to change based on avoiding growl.

[0027] Powertrain control methods allow a module controlling a hybrid powertrain to distribute torque production requests among various powertrain components based on an output torque requirement and powertrain control priorities. Transmission settings are similarly controlled based on the desired powertrain operation. The operation of a test or model powertrain through various parameter ranges may be modeled through experimentation, calibration, modeling, or other means designed to evaluate powertrain performance, and the distribution of torque production requests and transmission settings of a subsequent powertrain are controlled during operation based on the modeled operation.According to an exemplary control method, a control algorithm balances powertrain control priorities based on optimizing a control penalty function. Violations of different control priorities invoke penalties, and a control solution based on a least-penalty approach is chosen to control the powertrain. Penalty values ​​may be assigned to operation in growl-inducing regions, and powertrain operation in these growl-inducing regions may be minimized or eliminated based on the assigned penalty.

[0028] Fig.2 illustrates data from an example powertrain plotted in a domain from engine torque to output torque, illustrating regions where growl is possible and not possible at near-zero output torque. Horizontal axis 202 illustrates output torque, and vertical axis 204 illustrates engine torque. Line 220 illustrates a condition where engine torque is zero. Lines 222 and 240 define a region where engine torque and clutch reaction torque are within a lower threshold range, or an absolute value of the torque is lower than a threshold. Region 222 illustrates operation that should be avoided to stop growl from occurring. According to one embodiment, a value of + / -15 Newton meters from line 220 is used to define region 222.According to one embodiment, growling may be avoided by preventing operation of the vehicle from entering the illustrated region 222.

[0029] Fig. Figure 3 illustrates data for an exemplary engine showing an acceptable relationship between engine speed and engine torque based on a minimum drivability rating. Mapping the operation of a vehicle may, in one embodiment, be determined according to the impacts of various parameters on vehicle drivability. A correlation of engine speed and engine torque of an engine of a hybrid powertrain, where a motor of the powertrain has a low torque value, may be mapped, and a region or regions where engine speed and torque values ​​produce unacceptable NVH may be identified. Fig.Figure 3 illustrates engine speed on horizontal axis 302 and engine torque on vertical axis 304. Data graph 310 illustrates a gradation of NVH levels for the tested powertrain, with acceptable NVH in region 320. Region 330 illustrates a region where the zero-to-peak engine torque oscillations due to combustion are large enough for an audible growl to be observable when other components in the system are at growl-prone operating points. The intensity of the growl increases proportionally to engine torque and inversely to engine speed.

[0030] Fig.4 illustrates data from an example powertrain in a domain from engine torque to output torque, illustrating regions where near-zero output torque growl is possible and not possible, including a maximum value of engine torque dependent on engine speed, below which growl is not possible. The horizontal axis 402 illustrates output torque, and the vertical axis 404 illustrates engine torque. Line 420 illustrates a condition where engine torque is equal to zero. Lines 422 and 424 define a region where engine torque and reaction torque through the clutch are within a lower threshold range or an absolute value of the torque is less than a threshold.This region 440, defined by 422 and 424, is chosen based on the fact that growl is possible when engine torque is below a threshold, and region 440 illustrates operation that should be avoided to prevent growl from occurring. Line 430 illustrates a minimum engine torque at which growl may occur. Line 430 is influenced by operating parameters such as engine speed, with higher engine speed moving line 430 to a higher value on the vertical axis. Because both engine torque and motor torque must be within ranges that result in growl for growl to be possible, no restriction based on motor torque is required when engine operation is below the threshold engine torque defined by line 430.Region 410 illustrates a half-plane where operation cannot result in growling. Operation in a half-plane control strategy involves biasing one of the motors with positive torque or limiting the relevant torque operation of the motor to one-half of its full range. An extended half-plane involves adding the operating range allowed or illustrated below the prime mover's maximum torque line 430.

[0031] Fig.5 illustrates data from an exemplary powertrain in a domain from engine torque to output torque, illustrating a defined allowable operating range where near-zero output torque growl is possible and not possible, and operation at an example operating point with an engine operating alone to serve an accessory / cargo load outside of the allowable range. The horizontal axis 502 illustrates output torque, and the vertical axis 504 illustrates engine torque. Region 540 illustrates an operating region resulting in growl, similar to region 440 of Fig.4. Region 510 is illustrated, allowing powertrain operation without resulting in growl. Operating point 505 is illustrated at zero output torque and at any positive engine torque corresponding to an accessory / charging load. An accessory load includes torque required by the engine to power devices such as a motor / generator to charge the vehicle's batteries, a power steering pump, an air conditioning compressor, etc.

[0032] Point 505 lies outside of area 540, but, passing directly into area 510, can cause operation to enter area 540 and potentially cause growling to occur.

[0033] Fig. 6 illustrates the operating point of Fig. 5, including the permissible operating range of Fig.5 with an extended range of permissible operation corresponding to the operating point. The horizontal axis 602 illustrates the output torque, and the vertical axis 604 illustrates the torque of the prime mover. Region 640 illustrates an operating region that results in growling, similar to region 540 of Fig.5. Region 610 is illustrated, in which operation of the powertrain is permitted without resulting in growl. Operating point 605 is illustrated at zero output torque and at any positive engine torque corresponding to an accessory / cargo load. Point 605 lies outside of region 640. To permit a transition from point 605 to region 610, a region 612 encompassing point 605 and avoiding region 640 may be defined. To further avoid entry into region 640 and promote an orderly transition from point 605 to region 610, a disallowed region 642 may be defined. In the exemplary region 642 of Fig.6, a boundary between the permissible area 612 and the prohibited area 642 can be defined by creating a boundary 644 based on point 605 and the corner 643 of area 640. By allowing operation in areas 612 and 610, a transition can be controlled, avoiding areas that lead to growling.

[0034] Fig. Figure 7 illustrates the auxiliary unit charging operation with the engine switched on, including the operating point of Fig.5, operation with the engine off, and transitions therebetween. The horizontal axis 702 illustrates output torque, and the vertical axis 704 illustrates engine torque. Regions 740 and 742 illustrate regions that are prohibited due to growl. Region 740 and associated corner 743 are defined based on a zero engine torque line 720 intersecting point 707 where engine torque and output torque are equal to zero. The slope of line 720 ensures that corner 743 lies to the right of an output torque equal to a value of zero. Because corner 743 lies to the right of point 705, it can be shown that a transition between point 705 and point 707, where the engine is in a off state, remains outside of prohibited regions 740 and 742.If it can be shown that a transition from a point corresponding to an accessory / charging load to an engine-off point is outside of any prohibitive operating ranges, a control transition may be used whereby any transition to or from an accessory / charging state may be driven by an engine-off state to avoid growling.

[0035] Fig. Figure 8 illustrates the auxiliary unit charging operation with the engine switched on, including the operating point of Fig.5, and a transition to a second operating point at which the transmission transmits torque corresponding to an output torque. The horizontal axis 802 illustrates the output torque, and the vertical axis 804 illustrates the engine torque. By configuring a transition based on known boundaries of prohibitive operating regions, the transition from one point in one permissible region to a second point in another permissible region can be controlled. Once regions 840 and 842 are defined, corners 843 and 845 can be identified that illustrate transitions that can be controlled to avoid regions 840 and 842. A first portion 860 of a transition can be defined by defining a line segment from a first point 805 to a transition point 861 to the left of and below point 843.A second section 862 of the transition may be defined by defining a line segment from a first point 861 to a transition point 863 to the right and below point 845. An end section 864 of the transition may be defined by defining a line segment from 863 to a target operating point 809. The transition from . Fig. 8 is exemplary, and a number of transitions including curved segments, a single transition point, or three or more transition points to define further portions of the transition are contemplated, and the disclosure is not intended to be limited to the particular examples recited.

[0036] Fig. 9 illustrates the transition from Fig.8 into reverse gear. The horizontal axis 902 illustrates the output torque, and the vertical axis 904 illustrates the torque of the engine. Invalid areas 940 and 942 are illustrated. Based on a starting point 909 and a target point 905, the Fig. 8 may be performed in reverse to define a three-section transition 970.

[0037] Fig.10 illustrates lines of constant battery power as they relate to operating points in an engine torque / output torque domain. The horizontal axis 1202 illustrates output torque, and the vertical axis 1204 illustrates engine torque. Zone 1240 illustrates an operating region in which growl is enabled. Zone 1242 illustrates an operating region in which operation is prevented. Battery power lines 1210, 1211, 1212, 1213, 1214, and 1215 are illustrated, showing the increase in capacity of the battery and associated motor to enable operation. System operation is restricted above the respective lines. Line 1210 represents a battery condition where the powertrain cannot operate to transition from point 1205 around region 1240.Line 1215 illustrates a battery condition where the powertrain can easily operate to transition from point 1205 around region 1240. Battery power line 1213, which intersects the lower right corner of the growl region, represents the minimum battery required to operate at that point. When considering the evaluated operating point (represented by the star), an example method determines whether the required battery power will be available to complete the transition (taking into account battery power limits and accessory power). According to a method, if the transition is not enabled by the available battery power, engine speed may be increased to increase a minimum engine torque at which growl may occur, thereby moving a lower boundary of region 1240 higher on the vertical axis.

[0038] Fig.Figure 11 illustrates an exemplary process according to the disclosure. Table 2 is provided as a key to Fig. 11, where the blocks marked with numbers and the corresponding functions are as follows. Table 2 BLOCK BLOCK CONTENT 1102 start 1104 Are conditions present to allow growling, excluding engine torque and prime mover torque? 1106 Define an area of ​​improper drivetrain operation in which growling is possible 1108 Control the drivetrain based on avoiding the area 1110 End

[0039] The process starts at step 1102. At step 1104, a determination is made as to whether conditions necessary to enable growl are present, excluding engine torque having a particularly low range and prime mover torque being in a particular range. If the conditions are present, process 1100 transitions 1122 to step 1106. If conditions are not present, process 1100 transitions 1120 to step 1110. At step 1106, a prohibitive range is defined in which powertrain operation may enable growl. The ranges may be loaded from stored data or calculated in real-time based on operating parameters. According to one embodiment, battery power available to the powertrain may be evaluated at this step in the process to determine available transitions and thus avoid the range of prohibitive operation.At step 1108, the powertrain is controlled based on avoiding the defined area. At step 1110, process 1100 ends.

[0040] Growl can occur at a number of different locations in a powertrain. Each of the locations can exhibit different regions that lead to growl. The methods disclosed herein can be used to simultaneously prevent growl at each of the different locations. In one example, penalties in a control algorithm can be assigned to operation in any of the regions that lead to growl, thus preventing control of the powertrain from entering any of the regions where growl would be enabled.

[0041] Disclosed herein are transitions for moving from one powertrain operating point to another while avoiding a powertrain operating region where growl is enabled. Sometimes, rapid transitions in engine operation can enable a smooth transition or help avoid growl-enabled regions. Under some conditions, engine air or spark torque and engine speed can be used to quickly control the engine.

Claims

[1] A method of controlling a hybrid powertrain (100) comprising an engine (14), an electric motor (56, 72), and a transmission (10) to avoid a problem of noise, vibration, and harshness, referred to as growl, associated with play in the transmission (10), the method comprising: Monitoring the operation of the powertrain (100); wherein the conditions necessary for growling to occur include the motor torque (420) of the electric motor (56, 72) being less than a threshold motor torque (424, 422), the torque (404; 804; 904; 1204) of the prime mover (14) being greater than a threshold torque (430; 630) of the prime mover (14); an output speed of the transmission (10) being between an identified minimum speed of the output shaft (64) and an identified maximum speed of the output shaft (64); and clutches (70, 62, 73, 75) in the transmission (10) being engaged (1104) in a clutch condition resulting in growling; wherein, in a domain from engine torque (404; 504, 604; 704; 804; 904; 1204) to output torque (402; 502; 602; 702; 802; 902; 1202), the operating range (440; 540; 640, 642; 740, 742; 840, 842; 940, 942; 1240, 1242) of the powertrain (100) in which growl is enabled is determined based on the threshold engine torque (424, 422) and is based on the threshold engine torque (430; 530) (1106); when the conditions that can lead to growling are present and an initial operating point (805; 909) of the electric motor (56, 72) must be transferred to a target operating point (809; 905), wherein the transfer cannot be achieved by solely changing the operating point of the electric motor (56, 72) without passing through the region (840, 842; 940, 942) in which growling can occur, Controlling the powertrain (100) based on avoiding the operating range (840, 842; 940, 942) of the powertrain (100) in which the growling is enabled, wherein controlling the powertrain (100) comprises: Monitoring an initial operating point (805; 909) of the drive train (100); Monitoring a target operating point (809; 905) of the drive train (100); Determining a transition point (843) to transition the driveline (100) from the initial operating point (805; 909) to the target operating point (809; 905) while remaining outside the growl-enabled operating range (840, 842; 940, 942) of the driveline (100); and Controlling a transition of the powertrain (100) from the initial operating point (805; 909) to the target operating point (809; 905) based on the transition point (843), wherein the torque of the prime mover (14) falls below the threshold torque (430; 630) of the prime mover (14) during the transition (1108). [2] The method of claim 1, wherein controlling the powertrain (100) comprises: Assigning a control penalty to the operation that would be within the operating range of the powertrain (100) in which the growl is enabled; and Controlling the drive train (100) based on the control penalty. [3] The method of claim 1, wherein controlling the powertrain (100) further comprises: Determining a plurality of transition points (843, 845); and Controlling the transition of the powertrain (100) based on the transition points (843, 845).

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