Method and system for shift control of a hybrid vehicle

Abstract

Method for switching control of a hybrid vehicle, comprising: (a) detecting an internal combustion engine torque; (b) determining a drive torque of an engine clutch based on the engine torque; (c) comparing the determined drive torque and a predetermined permissible transmission torque of the internal combustion engine clutch; and (d) increasing an instantaneous shift time of the engine clutch by a predetermined value when the determined drive torque is greater than the allowable transmission torque, and using the increased shift time.

Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to Korean Patent Application No. 10-2013-0095813, filed on August 13, 2013, the entire contents of which are incorporated herein for all purposes by this reference. BACKGROUND OF THE INVENTIONField of the invention

[0002] The present invention relates to a method and system for shift control of a hybrid vehicle. In particular, the present invention relates to a method and system for shift control of a hybrid vehicle that prevent engine clutch slippage from occurring by controlling a shift time when, under adverse driving conditions, a transmission torque of an engine clutch is greater than a permissible transmission torque. Description of related technology

[0003] As is well known in the art, a hybrid vehicle uses a combined internal combustion engine and a battery power supply. This means that the hybrid vehicle efficiently combines the power of the internal combustion engine and the power of a traction motor for use.

[0004] As in Fig. 1, the hybrid vehicle may include, for example, an engine 10, a drive motor 20, an engine clutch 30 for interrupting power between the engine 10 and the drive motor 20, a transmission 40, a differential gear device 50, a battery 60, an integrated starter generator 70 for starting the engine 10 or generating electric power by rotational force of the engine 10, and vehicle wheels 80.

[0005] In addition, the hybrid vehicle may include a hybrid control unit (HCU) 200 for controlling an overall operation of the hybrid vehicle, an engine control unit (ECU) 110 for controlling an operation of the engine 10, a motor control unit (MCU) 120 for controlling an operation of the drive motor 20, a transmission control unit (TCU) 140 for controlling an operation of the transmission 40, and a battery control unit (BCU) 160 for controlling and managing the battery 60.

[0006] The battery control device 160 may be called a battery management system (BMS). The integrated starter generator 70 may be called an integrated starter & generator (ISG) or a hybrid starter & generator (HSG).

[0007] The hybrid vehicle can be driven in a drive mode such as an electric vehicle (EV) mode, which is a pure electric vehicle mode that uses only the power of the drive motor 20, a hybrid vehicle (HEV) mode, which uses the rotational power of the internal combustion engine 10 as the main drive and uses the rotational power of the drive motor 20 as the auxiliary drive, and a regenerative braking (RB) mode for collecting braking and inertia energy during travel by deceleration or inertia of the vehicle using power generation of the drive motor 20 to charge the battery 60.

[0008] The hybrid vehicle may utilize a dry-type engine clutch, and the dry-type engine clutch should be kept fully engaged during gear shifting. Therefore, the allowable transmission torque of the dry-type engine clutch can be determined by the engine, the rotational inertia of the engine, the angular acceleration, and the engine torque.

[0009] However, engine clutch slippage may occur when the hybrid vehicle is operating under adverse driving conditions because the transmission torque is greater than the allowable transmission torque. For example, engine clutch slippage may occur when the hybrid vehicle is operating at an extremely low temperature or when the hybrid vehicle shifts gears in response to additional engine torque.

[0010] This means that when the hybrid vehicle is operated under adverse conditions, engine clutch slippage may occur during gear shifting due to a difference in rotational inertia between the motor and the engine, which is generated when the transmission torque is greater than the allowable transmission torque. When such engine clutch slippage occurs, the hybrid vehicle is negatively affected in terms of gear shifting reliability, vehicle vibration, and fuel consumption.

[0011] In order to avoid the above problem, the allowable transmission torque of the engine clutch is increased, but the dimension of the engine clutch and an installation space for its installation must be increased.

[0012] DE 690 18 417 T2 and DE 10 2005 033 077 A1 each disclose a method for shift control of a hybrid vehicle, comprising: (a) detecting an internal combustion engine torque; (b) determining a drive torque of an internal combustion engine clutch based on the internal combustion engine torque; and (c) comparing the determined drive torque and a predetermined permissible transmission torque of the internal combustion engine clutch. US 2012 / 0 053 801 A1 discloses a method for a pure internal combustion engine vehicle in which a shift time is increased. SUMMARY

[0013] The object of the present invention is to provide a method and system for shift control of a hybrid vehicle, which have the advantages of preventing, by controlling a shift time, an internal combustion engine clutch slippage which is generated when, under unfavorable driving conditions, a transmission torque of an internal combustion engine clutch is greater than a permissible transmission torque.

[0014] This object is achieved by a method for controlling the shifting of a hybrid vehicle according to claim 1, as well as by a system for controlling the shifting of a hybrid vehicle. Further developments are the subject of the dependent claims.

[0015] According to one aspect of the present invention, a method for shift control of a hybrid vehicle may comprise: (a) detecting an engine torque, (b) determining a drive torque of an engine clutch based on the engine torque, (c) comparing the determined drive torque and a predetermined allowable transmission torque of the engine clutch, and (d) increasing a current shift time by a predetermined value when the determined drive torque is greater than the allowable transmission torque, and using the increased shift time.

[0016] The method may further comprise: (e) comparing the predetermined allowable transmission torque and the drive torque recalculated after using the shift time increased by the predetermined value, wherein steps (d) and (e) are repeatedly performed when the drive torque recalculated after using the shift time increased by the predetermined value is greater than the predetermined allowable transmission torque.

[0017] The drive torque is given by the equation T An = T E + (I Antrieb * a) determined, and T An is the drive torque, T E is the combustion engine torque, I Antrieb is the driving inertia or rotational inertia of an internal combustion engine, and a is the angular acceleration.

[0018] The drive torque is determined by multiplying the predetermined permissible transmission torque by a predetermined safety coefficient.

[0019] The switching time is increased by a predetermined ratio.

[0020] According to another aspect of the present invention, a shift control system of a hybrid vehicle may include: a dry-type engine clutch configured to control the transmission of power between an engine and a motor, an engine control unit (ECU) configured to control the engine, an engine control unit (MCU) configured to control the motor, a transmission control unit (TCU) configured to control a transmission, a hybrid control unit (HCU) configured to control an entire operation of the hybrid vehicle, and a shift control unit configured to increase a shift time by a predetermined value when a drive torque of the engine clutch determined based on an engine torque,a drive inertia and an angular acceleration, is greater than a predetermined permissible transmission torque of the internal combustion engine clutch, wherein the shift control device is operated by a predetermined program for carrying out the preceding method.

[0021] As described above, according to an exemplary embodiment of the present invention, the present invention prevents engine clutch slippage that occurs when a transmission torque of an engine clutch is larger than an allowable transmission torque under adverse driving conditions by controlling a shift timing, so that the shifting reliability and fuel consumption of the hybrid vehicle are improved.

[0022] The methods and apparatus of the present invention have other features and advantages which will be apparent from, or set forth in more detail in, the accompanying drawings incorporated herein and the following detailed description, which together serve to explain certain principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic block diagram of a typical hybrid vehicle. Fig. 2 is a schematic block diagram of a system for shift control of a hybrid vehicle according to an exemplary embodiment of the present invention. Fig. 3 is a flowchart showing a method for shift control of a hybrid vehicle according to an exemplary embodiment of the present invention. Fig. 4 is a diagram for describing an operation of a method and system for shift control of a hybrid vehicle according to an exemplary embodiment of the present invention.

[0023] It should be understood that the attached drawings are not necessarily to scale and present a somewhat simplified representation of various features illustrating the basic principles of the invention. The specific design features of the present invention, including, for example, specific dimensions, orientations, positions, and shapes disclosed herein, will be determined in part by the particular intended application and usage environment.

[0024] In the figures, reference numerals refer to the same or equivalent parts of the present invention throughout the individual figures of the drawing. DETAILED DESCRIPTION

[0025] Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) have been described in connection with exemplary embodiments, it should be understood that the present description is not intended to limit the invention(s) to these exemplary embodiments. On the contrary, the invention(s) are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, and other embodiments which may be included within the scope of the invention as defined by the appended claims.

[0026] The present invention will be described more fully below with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art would appreciate, the described embodiments could be modified in various other ways without departing from the spirit or scope of the present invention.

[0027] Throughout this specification, unless expressly stated otherwise, "comprising" any components is to be understood as including other components rather than excluding any other components.

[0028] Throughout the description, identical components are given identical reference numerals.

[0029] Fig. 2 is a schematic block diagram of a system for shift control of a hybrid vehicle according to an exemplary embodiment of the present invention.

[0030] The shift control system of the hybrid vehicle according to an exemplary embodiment of the present invention controls a shift timing when a drive torque of an engine clutch of the hybrid vehicle is greater than a predetermined allowable transmission torque.

[0031] The system for controlling the hybrid vehicle according to an exemplary embodiment of the present invention may include an engine clutch 30 for controlling transmission of power between an engine 10 and a motor 20, an engine control unit (ECU) 110 for controlling the engine 10, an engine control unit (MCU) 120 for controlling the motor 20, a transmission control unit (TCU) 140 for controlling a transmission 40, and a control unit 300 for increasing a shift time by a predetermined value when a drive torque of the engine clutch 30, which is calculated based on an engine torque, a drive inertia, and an angular acceleration, is greater than a predetermined allowable transmission torque of the engine clutch 30.

[0032] The internal combustion engine 10, the motor 20, the transmission 40, the internal combustion engine control device 110, the motor control device 120 and the transmission control device 140 may be installed in a conventional hybrid vehicle, as in Fig. 1 is shown.

[0033] The engine clutch 30 according to an exemplary embodiment of the present invention may preferably be a dry type engine clutch.

[0034] The control device 300 may be implemented with one or more microprocessors operated by a predetermined program or hardware including the microprocessor, and the predetermined program includes a series of instructions for performing a method for shift control of a hybrid vehicle according to an exemplary embodiment of the present invention, which will be described below.

[0035] The control device 300 according to an exemplary embodiment of the present invention may preferably have a function of a hybrid control unit (HCU) 200 as shown in Fig. 1. That is, the control device 300 may include the hybrid control device 200 or be incorporated into the hybrid control device 200.

[0036] Hereinafter, the method for shift control of the vehicle according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

[0037] Fig. 3 is a flowchart showing a method for shift control of a hybrid vehicle according to an exemplary embodiment of the present invention.

[0038] As in Fig. As shown in Figure 3, in step S110, the controller 300 detects engine torque while the hybrid vehicle is operating. For example, the controller 300 may utilize the engine torque detected by the engine control unit ECU 110. The fact that the engine control unit ECU 110 detects engine torque is well known, so a detailed description thereof is omitted from the present specification.

[0039] Once the engine torque is detected, the controller 300 calculates the drive torque of the engine clutch 30 in step S120. The controller 300 may use the engine torque while calculating the drive torque. For example, the controller 300 may calculate the drive torque using the following equation. TAn=TE+(IDrive*a) (T An , drive torque, TE , combustion engine torque, I Antrieb , drive inertia or rotational inertia of the combustion engine, a, angular acceleration)

[0040] The controller 300 may calculate the drive torque according to the above equation, but it should be understood that the present invention is not limited thereto. The controller 300 may calculate the drive torque by any method well known in the art. Likewise, the controller 300 may calculate the drive torque by multiplying an allowable transmission torque of the engine clutch 30, which will be described later, by a predetermined safety coefficient (for example, 0.8).

[0041] The driving inertia and the angular acceleration of the engine clutch 30 in the above equations are calculated or detected in the art, so a detailed description thereof is omitted from the present specification.

[0042] The drive inertia of the internal combustion engine clutch 30 may be the rotational inertia of the internal combustion engine.

[0043] When the drive torque is calculated, the controller 300 compares the drive torque and a predetermined allowable transmission torque in step S130.

[0044] The allowable transmission torque may be a predetermined value found using an available value of the engine clutch 30.

[0045] After comparing the drive torque and the allowable transmission torque in step S130, if the drive torque is greater than the allowable transmission torque, the controller 300 increases a current shift time (for example, by 0.3 seconds) in step S140.

[0046] For example, when the drive torque is greater than the allowable transmission torque, the controller 300 may increase the instantaneous shift time from 0.3 seconds to 0.7 seconds, as shown in Fig. 4 is shown.

[0047] Previously, the switching time was set as the short 0.3 seconds, as in Fig. As shown in Figure 4(A), when the drive torque was greater than the allowable transmission torque, slippage of the engine clutch 30 occurred because the variation of the engine speed and / or the motor speed was 3000 (rpm) / s. That is, previously, the shift time was kept short when the drive torque was greater than the allowable transmission torque. Therefore, due to the difference in rotational inertia of the engine 10 and the motor 20, the engine speed did not follow the deceleration of the engine speed due to the shifting, so slippage of the engine clutch 30 occurred.

[0048] In contrast, according to an exemplary embodiment of the present invention, the controller 300 may increase the switching time by a predetermined value, for example, to 0.7 seconds, as shown in Fig.4(B) when the drive torque is greater than the allowable transmission torque, so that the control device 300 can prevent the slippage of the engine clutch 20 that occurred earlier.

[0049] That is, when the shift time is extended to 0.7 seconds when the drive torque is larger than the allowable transmission torque, the variation of the engine speed and / or the motor speed is 1740 (rpm) / s, and the newly calculated drive torque (S150) is reduced accordingly, so that the slip of the engine clutch 30 does not occur because the engine speed is almost equal to the motor speed.

[0050] If the case occurs as described above that the drive torque is greater than the allowable transmission torque when the hybrid vehicle is operated under unfavorable drive conditions, for example, at less than -40 degrees C, the control device 300 can perform the method according to an exemplary embodiment of the present invention only under predetermined drive conditions, but it is understood that the present invention is not limited thereto.

[0051] If the drive torque recalculated in step S150 based on the increased shift time in S140 is still greater than the allowable transmission torque (S160), the controller 300 repeatedly performs the steps after S140 to try to reduce the drive torque by increasing the shift time.

[0052] The switching time is increased in step S140 by a predetermined ratio, for example from 100 to 250 percent of the current switching time.

[0053] If the drive torque is less than or equal to the allowable transmission torque in steps S130 and / or S160, the controller 300 uses each corresponding shift time for shifting in step S170.

[0054] Thereby, according to an exemplary embodiment of the present invention, the problem that engine clutch slippage occurs can be solved by controlling the shift time without increasing the size of the engine clutch.

[0055] For ease of explanation and precise definition in the appended claims, the terms "top," "bottom," "inside," and "outside" are used to describe features of the exemplary embodiments with reference to the positions of such features as shown in the figures.

[0056] The foregoing descriptions of the specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and use various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the claims appended hereto.

Claims

[1] A method for controlling the shifting of a hybrid vehicle, comprising: (a) detecting an internal combustion engine torque; (b) determining a drive torque of an engine clutch based on the engine torque; (c) comparing the determined drive torque and a predetermined permissible transmission torque of the internal combustion engine clutch; and (d) increasing an instantaneous shift time of the engine clutch by a predetermined value when the determined drive torque is greater than the allowable transmission torque, and using the increased shift time. [2] The method of claim 1, further comprising: (e) comparing the predetermined allowable transmission torque and the drive torque recalculated after using the shift time increased by the predetermined value, wherein steps (d) and (e) are repeatedly performed when the drive torque recalculated after using the shift time increased by the predetermined value is greater than the predetermined allowable transmission torque. [3] Method according to claim 1, where the drive torque is given by the equation T An = T E + (I Antrieb * a) is determined, and where T An is the drive torque, T E is the combustion engine torque, I Antrieb is the driving inertia or rotational inertia of an internal combustion engine, and a is the angular acceleration. [4] A method according to claim 1, wherein the drive torque is determined by multiplying the predetermined allowable transmission torque by a predetermined safety coefficient. [5] The method of claim 1, wherein the switching time is increased by a predetermined ratio. [6] System for controlling the gear shift of a hybrid vehicle, comprising: a dry-type internal combustion engine clutch configured to control the transmission of power between an internal combustion engine and a motor; an engine control unit (ECU) configured to control the engine; a motor control unit (MCU) configured to control the motor; a transmission control unit (TCU) configured to control a transmission; a hybrid control unit (HCU) configured to control an overall operation of the hybrid vehicle; and a shift control device configured to increase a shift time of the engine clutch by a predetermined value when a drive torque of the engine clutch, which is determined on the basis of an engine torque, a drive inertia, and an angular acceleration, is greater than a predetermined allowable transmission torque of the engine clutch, wherein the switching control device is operated by a predetermined program for carrying out the method according to claim 1.

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