KR102598559B1 - Control method for power-off downshift of hybrid electric vehicle - Google Patents

Abstract

The present invention provides a shift control method for a hybrid vehicle that can generate a desired vehicle deceleration without generating a sense of acceleration of the vehicle during a power-off downshift, and can achieve shortened shift time and improved drivability. The main purpose is to provide. In order to achieve the above-mentioned purpose, the hydraulic braking device is controlled during the shift process of power-off downshifting to generate hydraulic braking force, and at the same time, the transmission input torque, which is the motor, is based on the actual hydraulic braking torque estimate, which is an estimate of the hydraulic braking torque. A shift control method for a hybrid vehicle characterized by controlling torque is disclosed.

Description

{Control method for power-off downshift of hybrid electric vehicle}

The present invention relates to a method for controlling gear shifts in a hybrid vehicle, and more specifically, to a method for controlling gear shifts in a hybrid vehicle when a power-off downshift is requested by manipulating the shift lever of the driver while the hybrid vehicle is coasting.

A hybrid vehicle refers to a vehicle that uses two or more different types of drive sources, and generally refers to a vehicle driven by an internal combustion engine (ICE) and an electric motor.

Hybrid vehicles can output optimal torque and maximize fuel efficiency depending on how the engine and motor operate harmoniously during the driving process.

Hybrid vehicles can have a drivetrain with various structures. The TMED (Transmission Mounted Electric Device) hybrid system, which connects the engine and motor through an engine clutch and connects a transmission to the motor output side, is known.

Figure 1 is a diagram illustrating the power train configuration of a hybrid vehicle, illustrating the configuration of a TMED hybrid system in which a motor 3 and a transmission 4 are connected.

As shown, in the TMED hybrid system, the transmission (4) is mounted on the output side of the vehicle driving motor (3) and the motor output shaft is connected to the transmission input shaft, so the motor speed is equal to the transmission input shaft rotation speed (i.e., transmission input speed). do.

Looking at the configuration, the TMED hybrid system consists of the engine (1) and motor (3), which are the driving sources for driving the vehicle, the engine clutch (2) interposed between the engine (1) and motor (3), and the output side of the motor (3). It includes a transmission 4 connected to a transmission 4, an inverter 5 for driving the motor 3, and a battery 6 connected to the motor 3 through the inverter 5 so that it can be charged and discharged.

In this configuration, the engine clutch 2 selectively engages or disengages to connect or disconnect the engine 1 and the motor 3 to enable power transmission.

In order to drive the motor 3, the inverter 5 converts the direct current from the battery 6 into three-phase alternating current and applies it to the motor 3.

In addition, the transmission 4 shifts the rotational power of the motor 3 or the combined rotational power of the engine 1 and the motor 3 and transmits it to the drive wheel through the drive shaft. The transmission 4 is an automatic transmission. , AT) or a dual clutch transmission (DCT) may be used.

In addition, the TMED hybrid system may include a hybrid starter and generator (HSG) 7, which is a motor that is connected to the engine 1 to transmit power and starts the engine or generates power using rotational force transmitted from the engine.

The HSG (7) operates as a motor or as a generator, and is connected to the engine to enable constant power transmission, so it can be used to control engine speed.

Hybrid vehicles equipped with the above system run in EV (Electric Vehicle) mode, which is a pure electric vehicle mode that runs using only the power of the motor (3), or by using the power of the engine (1) and the power of the motor (3) in combination. It can be driven in HEV (Hybrid Electric Vehicle) mode.

In addition, when the vehicle is braking or coasting due to inertia, a regenerative mode is performed in which the vehicle's kinetic energy is recovered through the motor 3 to charge the battery 6.

In the regenerative mode, the motor 3 receives the vehicle's kinetic energy through the vehicle wheels, and at this time, the motor 3 operates as a generator and charges the battery 6 through the inverter 5.

Meanwhile, in vehicles equipped with an automatic transmission (AT) or dual clutch transmission (DCT), a power-off downshift occurs when the vehicle does not drive on its own, but rather when the driver does not press the brake or accelerator pedals. During coasting, which is driving by inertia (accelerator pedal tip-out and brake off), the vehicle's gear shift is lowered by the driver's operation of the shift lever (e.g., 2nd → 1st gear) ).

This power-off downshift is a different concept from a near-stop downshift that occurs beyond the lowest downshift line preset in the shift pattern.

Power-off downshifting is often done to obtain an engine braking effect without the driver pressing the brake pedal, and can occur when the driver operates the shift lever to a low gear to apply the engine brake while the vehicle is coasting.

As such, power-off downshifting is a case where the driver intentionally wants to slow down the vehicle, so quick shifting and creating a sufficient sense of deceleration are essential in a power-off downshifting situation.

Therefore, when a power-off downshift is performed in a hybrid vehicle, a negative torque is applied to the transmission input shaft by performing coast regeneration by the motor to simulate a situation similar to the engine braking of a conventional internal combustion engine vehicle. Authorize.

Figure 2 is a diagram showing motor speed and torque states during a power-off downshift shift process according to the prior art.

Figure 2 shows two diagrams with diagrams shown on the upper and lower sides, respectively. In the upper diagram, the vertical axis represents speed (ω) and the horizontal axis represents time, and in the lower diagram, the vertical axis represents torque (TQ) and the horizontal axis represents time. represents.

Additionally, in the lower diagram, based on the horizontal axis (TQ = 0 Nm), the area below represents the negative (-) torque area, and the area above represents the positive (+) torque area.

In addition, in the diagram of FIG. 2, N _Mj represents the target stage transmission input shaft synchronous speed, and N _M represents the transmission input shaft rotation speed (transmission input speed). In the TMED hybrid system, the transmission input shaft rotation speed (N _M ) is the motor speed and same.

The target stage refers to the shift range to be reached after power-off downshifting, that is, the target shift range after shifting. In the following description, the shift ranges before and after downshifting will be referred to as the previous stage and the target stage, respectively.

In addition, in the following description, the release element and engagement element refer to the clutch in the transmission, and in the diagram of FIG. 2, T _R represents the transmission torque of the transmission release element (release clutch), and TC _R represents the clutch torque of the transmission release element. indicates.

T _A represents the transmission torque of the transmission coupling element (engagement clutch), TC _A represents the clutch torque of the transmission coupling element, T _o represents the transmission output torque (i.e. transmission output shaft torque), and T _i represents the transmission input torque ( That is, it represents the transmission input shaft torque).

In the TEMD hybrid system, the transmission input torque becomes the motor torque.

Transmission torque (T _R , T _A ) may refer to the output torque at the rear end of the clutch transmitted through the relevant clutch (releasing element, engaging element), and clutch torque (TC _R , TC _A ) may refer to the clutch torque applied to the relevant clutch. It may mean shear input torque.

In addition, in the shifting process, the release element of the previous stage is released to be in a power disconnection state (clutch release) and then the engagement element of the target stage is fastened to be in a power connection state (clutch engagement), so in the following description, the release element and the engagement element are can be understood to mean the elements (clutch) of the previous stage and the target stage.

Therefore, the transmission torque (clutch rear-stage output torque) transmitted through the clutch in the previous stage before and after shifting refers to the transmission torque (T _R ) of the release element (release clutch), and the transmission torque transmitted through the clutch in the target stage Can be understood to mean the transmission torque (T _A ) of the coupling element (coupling clutch).

Of course, when the transmission torque (T _R ,T _A ) is output and transmitted through the rear end of each clutch, the torque applied and input to the front end of the clutch is the clutch torque (TC _R ,TC _A ).

During a conventional power-off downshift, as shown in FIG. 2, the transmission control unit (TCU) quickly releases the release clutch (release element) after point A (reduces T _R to 0), and the torque increases. is required to be requested.

This torque increase request causes the Hybrid Control Unit (HCU) and the Motor Control Unit to perform cooperative control, increasing the transmission input torque (motor torque) (T _i ) and rotating the transmission input shaft. Increase the speed (motor speed) (N _M ) to approach the target gearbox input shaft synchronous speed (N _Mj ).

The above torque increase control uses a method of requesting an increase in a predetermined amount of torque or monitoring the motor speed to provide feedback, which is caused by the difference in transmission torque before and after shifting (|T _A -T _R |) when applying a large amount of clutch torque. The purpose is to avoid shock.

In addition, the transmission output torque (T _o ) after the power-off downshift (after points C and D) falls (i.e. decreases) compared to the transmission output torque before the power-off downshift (before point A).

That is, when the transmission output torque (T _o ) is a negative torque, when comparing before and after shifting, the transmission output torque (T _o ) decreases (reduces) in the negative torque region of FIG. 2. This means that after shifting, the absolute value of the transmission output torque (T _o ) increases compared to before shifting.

However, looking more closely at the transmission output torque (T _o ) shown as negative (-) torque in FIG. 2, as shown in the circle in FIG. 2, the transmission within the negative (-) torque region from point A to point B is The output torque (T _o ) rises to 0 (the absolute value of the transmission output torque decreases), and then falls again from point B to before point C (the absolute value of the transmission output torque increases).

According to the prior art, the transmission torque (T _R ) of the release element (release clutch) is released quickly, so the synchronization with the previous stage is released, and the vehicle deceleration expected from the engine brake is not achieved, but rather the vehicle acceleration temporarily increases. The problem exists.

At this time, even if the transmission torque (T _A ) of the coupling clutch is applied, it is difficult to avoid a decrease in vehicle deceleration, and in severe cases, as shown in the diagram in Figure 2, it fails to secure a constant sense of deceleration, causing the car to jump forward and then back after operating the driver's shift lever. A pulling feeling (a feeling caused by a sudden rise and then fall of T _o ) may occur.

In the end, when the driver receives the feeling of the vehicle suddenly jumping forward (i.e., a feeling of acceleration) as described above, even though the transmission input torque is very low due to regenerative braking when decelerating the vehicle, and the driver wants to obtain the effect of engine braking during deceleration, it can be extremely difficult. It can be accepted as a dangerous situation.

In addition, if the shift controller fails to actively request a torque increase due to the above-mentioned reasons, or if the torque of the coupling clutch is not used significantly to prevent the occurrence of shock due to a large difference in transmission torque before and after shift synchronization, the shift time is shortened. As delays occur, drivability deteriorates.

Accordingly, the present invention was created to solve the above problems, and it is possible to generate the desired vehicle deceleration without generating a sense of acceleration of the vehicle during the power-off downshift shift process, and achieves shortened shift time and improved drivability. The purpose is to provide a shift control method for hybrid vehicles that can be used.

In order to achieve the above object, according to an embodiment of the present invention, when the controller determines that there is a shift request for power-off downshift according to the driver's downshift operation while the vehicle is coasting, the motor torque is adjusted to negative (-). Performing a transmission input torque release control to release the transmission input torque by reducing it based on an absolute value in the torque range of ); When release of the transmission input torque is completed, controlling the release clutch of the transmission to be released by the controller; In a state in which the release clutch of the transmission is released, the controller controls the motor speed so that the rotational speed of the transmission input shaft reaches the set target stage synchronous speed of the target stage after shifting; When the transmission input shaft rotation speed reaches the target stage synchronous speed, controlling the coupling clutch of the transmission to be engaged by the controller; And a step of the controller performing a transmission input torque return control in which the transmission input torque is reapplied by increasing the motor torque in the negative torque region based on the absolute value, wherein the controller performs the steps when the steps are performed. Power-off downshift of a hybrid vehicle, characterized in that it generates hydraulic braking force by controlling the hydraulic braking device while simultaneously controlling the motor torque, which is the transmission input torque, based on the actual hydraulic braking torque estimate, which is an estimate of the hydraulic braking torque. Provides a control method.

Accordingly, according to the power-off downshift control method of a hybrid vehicle according to the present invention, a desired vehicle deceleration can be generated without generating a sense of acceleration of the vehicle during the power-off downshift shift process, shortening shift time and improving drivability. can be achieved.

Figure 1 is a diagram schematically showing the power train configuration of a typical hybrid vehicle.
Figure 2 is a diagram illustrating a power-off downshift control state according to the prior art.
Figure 3 is a system configuration diagram of a hybrid vehicle to which the power-off downshift control method of the present invention is applied.
Figure 4 is a block diagram showing the main functions performed by each controller in a plurality of vehicles in the present invention.
Figure 5 is a flowchart showing the power-off downshift control process of a hybrid vehicle according to an embodiment of the present invention.
Figure 6 is a diagram showing an example of power-off downshift control of a hybrid vehicle according to an embodiment of the present invention.
Figure 7 is a diagram illustrating a torque state during cooperative control for releasing transmission input torque during the power-off downshift control process of a hybrid vehicle according to an embodiment of the present invention.

Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms.

When a part in the entire specification is said to “include” a certain element, this means that it may further include other elements rather than excluding other elements, unless specifically stated to the contrary.

The present invention is a shift control of a hybrid vehicle that can generate a desired vehicle deceleration without generating a sense of acceleration of the vehicle during the shift process of power-off downshift, and can achieve shortened shift time and improved drivability. The goal is to provide a method.

To this end, an improved method of performing simultaneous cooperative control such as speed control and torque control for the motor that drives the vehicle during power-off downshifting, control of release elements and engagement elements in the transmission, and hydraulic brake control is disclosed. do.

In the present invention, power-off downshifting is performed during coasting (accelerator pedal tip-out and brake off) in which the vehicle is driven by inertia in an idling state without the driver pressing the brake pedal and accelerator pedal, rather than driving on its own. This is a shift that occurs due to the driver's downshift operation (e.g., operating the shift lever from 2nd gear to 1st gear), and is a shift in which the vehicle's gear shift is lowered.

The power-off downshift control method of the present invention can be applied to hybrid vehicles in which regenerative braking and hydraulic braking are implemented. For example, it can be applied to TMED hybrid vehicles, and can also be applied to automatic transmission (AT) or dual clutch transmission (DCT). ) can be applied to vehicles equipped with

In addition, the power-off downshift control process of the present invention can be performed using known in-vehicle controllers, such as a hybrid controller (Hybrid Control Unit, HCU), transmission control unit (TCU), and motor controller (Motor Control Unit, MCU). , it can be performed through cooperative control by a plurality of controllers, such as a brake controller (Brake Control Unit, BCU), or it can be performed by one controller having the integrated functions of these controllers.

Hereinafter, the power-off downshift control method of a hybrid vehicle according to an embodiment of the present invention will be described in detail with reference to FIGS. 3 to 7.

Figure 3 is a system configuration diagram of a hybrid vehicle to which the power-off downshift control of the present invention is applied, showing the system configuration of a TMED hybrid vehicle.

As shown, a hybrid vehicle includes an engine 90 and a motor 110 that are driving sources for driving the vehicle, an engine clutch 100 interposed between the engine 90 and the motor 110, and an output side of the motor 110. It includes a transmission 120 connected to.

In addition, hybrid vehicles are equipped with a hybrid controller (HCU) 20, which is a higher-level controller that controls overall vehicle operation, and are equipped with various other controllers that control various devices of the vehicle.

For example, status information of the engine controller (ECU) 30 that controls the operation of the engine 90, the transmission controller (TCU) 40 that controls the operation of the transmission 120, and the battery 70 are collected and A battery controller (BMS) 50 that utilizes, provides, and performs control for battery management, a motor controller 60 for driving and controlling the motor 110, and a brake controller (BCU) that performs braking control of the vehicle ( 80) etc. are provided.

Here, the brake controller 80 may be an electronic control unit of an active hydraulic booster (AHB), known as a regenerative braking device for eco-friendly vehicles that performs regenerative braking and hydraulic braking control.

Additionally, the battery 70 is connected to the motor 110 through an inverter (not shown) of the motor controller 60 to enable charging and discharging.

In FIG. 3, reference numeral 130 represents a hydraulic circuit that generates brake hydraulic pressure, and reference numeral 131 represents a wheel brake installed on the vehicle wheel 9 to generate hydraulic braking force (i.e., friction braking force).

The hybrid vehicle is equipped with a hydraulic braking device (friction braking device), and the hydraulic braking device is installed on a hydraulic circuit 130 that generates brake hydraulic pressure and the vehicle wheel 9 to apply brake hydraulic pressure generated in the hydraulic circuit 10. It includes a wheel brake 131 that generates braking force (friction braking force).

The brake controller 80 controls the operation of the hydraulic braking device. It controls the operation of hydraulic actuators and valves, not shown, in the hydraulic circuit 130 to control the brake hydraulic pressure applied to the wheel cylinder of the wheel brake 131. do.

In addition, the hybrid controller 20 and each controller perform cooperative control of devices in the vehicle while exchanging information with each other through CAN communication. The upper controller collects various information from the lower controllers and sends control commands to the lower controllers. Deliver.

The driving information detection unit indicated by reference numeral 10 in FIG. 3 is for detecting vehicle driving information, and the vehicle driving information may include driving input information and vehicle status information.

The driving input information may include the driver's brake pedal operation status, accelerator pedal operation status, and shift lever operation status, and vehicle status information may include vehicle speed and motor speed.

The driving information detection unit 10 includes an accelerator pedal sensor (APS), which outputs a signal according to the driver's operation of the accelerator pedal, and a brake pedal sensor (Brake Pedal Sensor, BPS), which outputs a signal according to the driver's operation of the brake pedal. , may include a shift detection unit for detecting the position of the shift lever, a vehicle speed detection unit for detecting vehicle speed, and a motor speed detection unit for detecting the motor speed, and these include a hybrid controller 20 and a shift controller 40, and the in-vehicle controller It can be connected to allow input of detection values.

Figure 4 is a block diagram showing the main functions performed by the in-vehicle controllers in the present invention. To describe the controllers involved in the control method of the present invention in more detail, the shift controller 40 is connected to the driving information detection unit 10. It is determined whether there is a request for a power-off downshift from the vehicle driving information detected by the vehicle.

The shift controller 40 determines from the vehicle driving information detected by the driving information detection unit 10 that, while the vehicle is coasting without the driver stepping on the accelerator pedal, the driver operates the shift lever to a lower range to enable shifting. (That is, when there is a downshift operation by the driver), it can be determined that there is a request for power-off downshifting.

In addition, the shift controller 40 receives a signal from the hybrid controller 20 during the power-off downshift shift process and controls the engagement and release of the clutch in the transmission 120, disengaging the transmission input torque for shifting. At this point, the release clutch is released, and after speed control for the transmission input shaft rotation speed is completed, control is performed to engage the engagement clutch.

The hybrid controller 20 sets the transmission input shaft rotation speed ( _N ) based on the target stage transmission input shaft synchronous speed (N _M ) (which is the speed of the vehicle drive source) is controlled.

In the TMED hybrid system, the transmission input shaft rotation speed (N _M ) is the same as the speed of the vehicle drive source connected to the transmission input side, that is, the speed of the motor, and the transmission input shaft rotation speed (N _M ) and the target stage transmission input shaft are synchronized. In order to match the speed (N _Mj ), the motor speed is increased during the speed change section so that the transmission input shaft rotation speed (N _M ) is equal to the target stage transmission input shaft synchronous speed (N _Mj ) (hereinafter abbreviated as 'target stage synchronous speed'). Control so that the speed is the same.

In addition, _the hybrid controller 20 transmits the target regenerative braking execution amount to the brake controller 80 and performs motor torque feedback control ( (Motor torque compensation control described later) is performed.

This motor speed control and motor torque feedback control is cooperative control between the hybrid controller (HCU) (20), transmission controller (TCU) (40), motor controller (MCU) (60), and brake controller (BCU) (80). It can be performed through

That is, the motor controller 60 controls the motor speed and motor torque according to commands from the hybrid controller 20, and the brake controller 80 controls the brake hydraulic pressure based on the target regenerative braking execution amount.

As described above, the control process according to the embodiment of the present invention can be performed by cooperative control between a plurality of controllers. Hereinafter, the plurality of controllers are divided according to function, and the divided plurality of controllers perform cooperative control. A description will be given of performing a control process according to an embodiment of the invention.

However, not only can a plurality of controllers be collectively described as one controller, but furthermore, one integrated controller can actually perform the control process according to an embodiment of the present invention.

FIG. 5 is a flowchart showing a power-off downshift control process of a hybrid vehicle according to an embodiment of the present invention, and FIG. 6 is a diagram showing an example of power-off downshift control of a hybrid vehicle according to an embodiment of the present invention. It shows the motor speed and torque status during the power-off downshift shift process.

In addition, Figure 7 is a diagram illustrating a torque state during cooperative control for releasing transmission input torque during the power-off downshift control process of a hybrid vehicle according to an embodiment of the present invention.

First, briefly explaining the drawings, FIG. 5 shows the main process of cooperative control performed by the hybrid controller (HCU) 20, the transmission controller (TCU) 40, and the brake controller (BCU) 80.

In addition, Figure 6 is a diagram in contrast to Figure 2 illustrating the prior art, and like Figure 2, two diagrams are shown on the upper and lower sides, respectively.

In the upper diagram of FIG. 6, the vertical axis represents speed (ω) and the horizontal axis represents time, and in the lower diagram, the vertical axis represents torque (TQ) and the horizontal axis represents time.

Additionally, in the lower diagram of FIG. 6, the area below the horizontal axis (TQ = 0 Nm) represents a negative (-) torque area, and the area above represents a positive (+) torque area.

In the diagram of FIG. 6, N _Mj represents the target stage synchronous speed, N _M represents the transmission input shaft rotation speed (transmission input speed), and in the TMED hybrid system, the transmission input shaft rotation speed is the same as the motor speed.

Here, the target range refers to the shift range to be reached after power-off downshifting, that is, the target shift range after shifting.

In the following description, the previous stage refers to the shift stage before downshifting, and the shift stages before and after downshifting are referred to as the previous stage and the target stage, respectively (e.g., in the case of shifting from 2nd to 1st gear, the previous stage is 2nd stage, Target stage 1).

In addition, in the following description, the release element and engagement element refer to the clutch in the transmission 120, and in the diagram of FIG. 6, T _R represents the transmission torque of the transmission release element (release clutch), and TC _R represents the transmission torque of the transmission release element. Indicates clutch torque.

In the diagram of FIG. 6, T _A represents the transmission torque of the transmission coupling element (coupling clutch), TC _A represents the clutch torque of the transmission coupling element, T _o represents the transmission output torque (i.e. transmission output shaft torque), and T _i represents the transmission input torque (i.e. transmission input shaft torque).

The transmission torque (T _R , T _A ) may mean the output torque at the rear end of the clutch transmitted through the corresponding clutch (releasing element, engaging element), and the clutch torque (TC _R , TC _A ) is the torque applied to the corresponding clutch. This may mean the clutch shear input torque.

That is, when the torque applied and input through the front end of each clutch is the clutch torque (TC _R , TC _A ), the torque output and transmitted through the rear end of each clutch is the transmission torque (T _R , T _A ).

In addition, during the shifting process, the release element of the previous stage is released so that the power is disconnected (clutch release), and then the engagement element of the target stage is fastened so that the power is connected (clutch engagement), so in the following description, the release element and the engagement element are used. can be understood to mean the clutches of the previous stage and the target stage, respectively.

That is, the release element (release clutch) refers to the previous stage clutch of the transmission 120 that is released during the shift process in the engaged state, and the engagement element (engagement clutch) refers to the transmission 120 that is engaged during the shift process in the released state. refers to the target stage clutch.

In addition, the transmission torque transmitted through the clutch at the previous stage (clutch rear-end output torque) is the transmission torque (T _R ) of the release element (release clutch), and the transmission torque transmitted through the clutch at the target stage is the transmission torque of the engagement element (engagement clutch). ) means the transmission torque (T _A ).

And, in Figure 6, (T _i ) _dmd represents the required torque based on the transmission input shaft, i _R represents the gear ratio of the previous stage of the transmission, and i _A represents the gear ratio of the transmission target stage.

At this time, the previous stage clutch (releasing element) transmission torque (T _R ) before shifting can be calculated as 'T _R = i _R × (T _i ) _dmd ', and the target stage clutch (engaging element) transmission torque (T _A ) can be calculated as 'T _A = i _A × (T _i ) _dmd '.

In addition, in FIG. 6, (T _i ) _{T_brk} represents the target regenerative braking execution amount, and T _B represents the actual hydraulic braking torque _estimate , which is an estimate of the actual hydraulic braking torque amount.

In addition, in FIG. 6, the transmission input torque T _i is a torque value controlled by the control of the controller or cooperative control of the controllers, and in the TMED hybrid system, the transmission input torque becomes the motor torque.

In the present invention, even if the driver does not operate the brake pedal, when a power-off downshift is requested, hydraulic braking torque (hydraulic braking force) is generated to simulate engine braking, and this hydraulic braking torque is also controlled by cooperative control of controllers. The torque becomes

Regarding the hydraulic braking torque, the actual hydraulic braking torque estimate (T _B ) is shown in the diagram of FIG. 6, and the actual hydraulic braking torque estimate (T _B ) is used as a variable in motor torque compensation control during the cooperative control process of the AB section. do.

In addition, the clutch torque (TC _R , TC _A ) values, that is, the clutch torque (TC _R ) value of the previous stage release element and the clutch torque (TC _A ) value of the target stage engagement element, are the clutch release output from the shift controller 40. It can be a command value for coupling (torque value to be applied to the clutch).

Referring to the diagram of FIG. 6, the clutch torque (TC _R ) of the release element is controlled to a value of 0 from point B entering the speed change section, and the clutch torque (TC _A ) is approved.

In the present invention, the torque controlled according to the command value is the clutch torque of the release element TC _R , the clutch torque of the coupling element TC _A , the transmission input torque T _i , etc., the transmission torque T _A and T _R , and the transmission output torque T _o etc. is the torque that appears as a result of control.

In addition, the torque values in FIG. 6 are all torque values based on the transmission output shaft, except for the transmission input torque T _i , the required torque based on the transmission input shaft (T _i ) _dmd , and the target regenerative braking execution amount (T _i ) _{T_brk} . .

That is, all of the transmission torques T _{R and} T _A , including the transmission output torque T o, and the clutch torques TC _{A and} TC _R are the transmission output shaft reference torque, and these torques are the gear stage (previous stage and target stage) of the transmission 120. However, it can be said to be the equivalent torque converted and converted to the torque value at the transmission output shaft considering the gear ratio corresponding to).

In addition, the transmission output shaft reference torque, in addition to the converted equivalent torque, may be a torque directly obtained or estimated and calculated based on the transmission output shaft. For example, the actual hydraulic braking torque amount is estimated based on the transmission output shaft. One value, the actual hydraulic braking torque estimate T _B, is also the torque based on the transmission output shaft.

However, in the diagram of FIG. 6, the target regenerative braking execution amount (T _i ) _{T_ brk,} which is the target regenerative braking torque value, and its maximum value '(i _A -i _R )/i _R ×|(T _i ) _dmd |' is the torque based on the transmission input shaft, similar to the transmission input torque (T _i ) and the required torque ((T _i ) _dmd ).

Hereinafter, the power-off downshift control process according to an embodiment of the present invention will be described step by step with reference to FIGS. 5 to 7. First, the shift controller 40 determines the current vehicle detected by the driving information detector 10. A power-off downshift shift request is detected from driving information.

In other words, the shift controller 40 determines whether there is a power-off downshift request based on current vehicle driving information.

Here, if there is a downshift operation by the driver while the vehicle is coasting, and if the shift range selected by the downshift operation is shiftable, the shift controller 40 is a situation in which a power-off downshift request is performed. It can be set to judge that it is.

That is, when the shift controller 40 determines the vehicle driving information detected by the driving information detection unit 10 while the vehicle is coasting without the driver pressing the brake pedal or accelerator pedal, the driver operates the shift lever to a low range. If the selected gear range is a gear range that can currently be shifted to, it is determined that there is a shift request for power-off downshifting.

Once it is determined that there is a request for power-off downshifting, shift control for power-off downshifting begins at point A in FIG. 6, and then the transmission input torque (T _i ) is changed from point A to point B. A cooperative control process is performed to release the transmission input torque until it reaches 0 (zero) torque.

In short, the entry condition for cooperative control to release the transmission input torque is a situation where there is a current power-off downshift shift request. At point A, the vehicle is coasting, and the driver presses the seat lever during coasting. If the operation is performed to a lower gear than before (driver downshift operation), and the gear range selected by operating the shift lever can be shifted, it is determined that there is a shift request for power-off downshift, and cooperative control is entered to release the transmission input torque. do.

During coasting, which is a vehicle driving condition in which a power-off downshift is performed, the engine 90 is in the off state and the engine clutch 100 is in the released state, so the transmission input torque (T _i ) becomes the motor torque.

This control from point A to point B (A-B section) is controlled by cooperative control of the transmission controller (TCU) 40, hybrid controller (HCU) 20, and brake controller (BCU) 80, as shown in FIG. is carried out by

In addition, although not shown in FIG. 5, since the motor torque must be controlled according to the torque command output by the hybrid controller 20 to release the transmission input torque and control the motor torque compensation, as will be described later, the motor controller 60 is also A-B Involved in cooperative control of sections.

To further explain the transmission input torque release control performed during the AB section with reference to FIG. 6, FIG. 6 is an example of brake non-application in which the driver does not operate the brake pedal, and the required torque based on the transmission input shaft ((T _i ) _dmd ) represents a certain example.

During the control process of the A-B section, the required torque is determined according to the vehicle driving state at point A, that is, the vehicle driving state at the time of entering the transmission input torque release control, and this required torque is used as the total braking torque of the braking force distribution method as described later. do.

Here, the vehicle driving state information may include vehicle speed, and the required torque may be a value determined according to the vehicle speed at point A.

In addition, during the control process of the AB section, the required torque used as the total braking torque may be the required torque based on the transmission input shaft ((T _i ) _dmd ) or the required torque based on the transmission output shaft ('i _A × (T _i ) _dmd '). there is.

In addition, the transmission input torque (T _i ) matches the required torque ((T _i ) _dmd ) based on the transmission input shaft before shifting until point A, but after point A when the power-off downshift control begins, the transmission input torque (T _i ) Transmission input torque release control is performed to reduce the absolute value and release it to a value of 0 until point B.

In the diagram of FIG. 6, the transmission input torque (T _i ) in the AB section is shown as negative (-) torque, so the absolute value of the transmission input torque in the AB section decreases, which means that the transmission input torque is negative (-). This means that the torque rises (increases) until it reaches a value of 0.

In the present invention, during the power-off downshift shift process, the transmission output torque (T _o ) increases significantly and then decreases as in the prior art (if the transmission output torque is expressed as a negative torque as shown in FIG. 2, it is It prevents the absolute value from greatly decreasing and then increasing), and generates hydraulic braking force while lowering the transmission output torque (T _o ) at a constant slope in the AB section of FIG. 6.

That is, in the process of power-off downshifting, even if the driver does not step on the brake pedal, hydraulic braking force is applied by controlling the operation of the hydraulic braking device (i.e. friction braking device) including the hydraulic circuit 130 and the wheel brake 131. (Friction braking force) is generated, and in order to generate this hydraulic braking force, cooperative control must be performed between the hybrid controller 20 and the brake controller 80.

At this time, in order to achieve cooperative control between the two controllers 20 and 80 and generate hydraulic braking force by the hydraulic braking device, the hybrid controller 20 determines and transmits the target regenerative braking amount to the brake controller 80. and the target regenerative braking execution amount (torque value) and hydraulic braking torque must satisfy the total braking torque.

Equation (1) below is the braking force distribution equation applied in eco-friendly vehicles in which regenerative braking is performed. As is known, braking force distribution is essential in cooperative control of regenerative braking and hydraulic braking.

Total braking torque = target regenerative braking performance + target hydraulic braking torque (1)

In the braking force distribution equation, each torque may be a torque determined by a value based on the transmission input shaft, or each torque may be a torque determined by a value based on the transmission output shaft.

When the driver presses the brake pedal, as when shifting gears before stopping, the brake controller 80 calculates the total braking torque according to the brake pedal value (BPS value) and then calculates the target regenerative braking amount (torque) from the hybrid controller 20. value) is received, and the target hydraulic braking torque (= friction braking torque) that satisfies Equation (1) above is determined.

However, in the present invention, the hybrid controller 20 and the brake controller 80 are cooperatively controlled even when the driver does not press the brake pedal, thereby generating hydraulic braking torque that satisfies the total braking torque.

That is, in the shift process of the power-off downshift of the present invention, even if the driver does not press the brake pedal, the hybrid controller 20 determines the target regenerative braking amount (torque value) and transmits it to the brake controller 80.

In addition, the brake controller 80 determines a target hydraulic braking torque (= friction braking torque) that satisfies Equation (1), which is a braking force distribution equation, from the target regenerative braking execution amount transmitted from the hybrid controller 20, and then determines the target hydraulic braking torque (= friction braking torque) The hydraulic braking device is controlled according to the hydraulic braking torque to generate the hydraulic braking force required during gear shifting.

At this time, the hybrid controller 20 sets the target regenerative braking execution amount ((T _i ) _{T_brk} ) transmitted to the brake controller 80 from the time of entering the transmission input torque release control until the time the transmission input torque release is completed. If possible, a value that increases at a constant slope over time is determined and transmitted.

Referring to FIG. 6, when the vehicle is coasting, up to point A, that is, up to the point of entering the transmission input torque release control, the required torque, that is, the required torque based on the transmission input shaft ((T _i ) _dmd ) and the target regenerative braking execution amount ((T _i ) _{T_brk} ) is consistent, but after entering the transmission input torque release control, the target regenerative braking execution amount ((T _i ) _{T_brk} ) can be seen to be determined as a value increased by a certain slope from the required torque ((T _i ) _dmd ). .

In equation (1) above, the hydraulic braking torque is the target value of the hydraulic braking torque to be generated during the power-off downshift shift process, that is, the target hydraulic braking torque. This target hydraulic braking torque may be the transmission input shaft reference torque. , It may be the transmission output shaft reference torque converted based on the transmission output shaft, and the target hydraulic braking torque based on this transmission output shaft is indicated as (T _B ) _T in FIG. 7.

In addition, in the present invention, the total braking torque must be determined to generate hydraulic braking torque even if the driver does not step on the brake pedal. In the present invention, the value of the total braking torque calculated by the brake controller 80 is used to determine the total braking torque of the hybrid controller 20. It is used by applying the required torque.

That is, the sum of the target regenerative braking execution amount and the target hydraulic braking torque satisfies the required torque, and here, the required torque may be the required torque ((T _i ) _dmd ) based on the transmission input shaft, as described above.

In addition, if the required torque based on the transmission input shaft is (T _i ) _dmd , the torque converted based on the transmission output shaft, that is, the required torque based on the transmission output shaft can be calculated as 'i _A × (T _i ) _dmd '.

During the power-off downshift shift process, the required torque ((T _i ) _dmd ) of the hybrid controller 20 is the regenerative torque during coasting, which is negative torque, that is, the torque of non-eco-friendly vehicles such as internal combustion engine vehicles. It is a negative torque that simulates the powertrain load during coasting.

The reason why the target regenerative braking amount is calculated in the A-B section during the power-off downshift shift process according to the present invention is because it is essential for cooperative control with the brake controller 80.

Since cooperative control of regenerative braking and hydraulic braking is performed even without brake pedal operation during the power-off downshift shift process according to the present invention, in order to use the braking force distribution equation such as Equation (1), the target regenerative braking amount is calculated. This is needed.

In addition, conventionally, all terms in the braking force distribution equation of 'total braking torque = target regenerative braking amount + hydraulic braking torque' were negative values, but in the present invention, the hydraulic braking torque is greater than the total braking torque. In order to obtain a value, the target regenerative braking amount in the A-B section is increased to reach a set positive (+) value.

That is, in FIG. 6, the maximum value of the target regenerative braking amount ((T _i ) _{T_brk} ), that is, the maximum target regenerative braking amount, is set to a positive (+) value.

Referring to FIG. 6, the target regenerative braking amount ((T _i ) _{T_brk} ) is the maximum positive value '(i _A -i _R )/i _R ×|(T _i ) _dmd at point B when the transmission input torque release is completed. After reaching '|', it can be seen that the above maximum value continues to be maintained until point D, which is the point of entering the transmission input torque return control, through the BC and CD sections described later.

As described above, in the present invention, the required torque ((T _i ) _dmd ) transmitted from the hybrid controller 20 to the shift controller 40 is used as the value of the total braking torque, which is used during the shift process as shown in FIG. 6. Assuming that it remains the same without change, in order to ensure that the transmission output torque (T _o ) falls at a constant slope in the AB section, the maximum value of the target regenerative braking amount in the above braking force distribution equation is set to a positive (+) value, and the hydraulic pressure Ensure that the absolute value of the braking torque is greater than the absolute value of the total braking torque.

In addition, the hybrid controller 20 ensures that the transmission output torque (T _o ) step before and after shifting occurs in the AB section for a quick sense of deceleration, and to this end, calculates the maximum target regenerative braking amount as in Equation (2) below and brakes. It is sent to the controller (80).

max((T _i ) _{T_ brk＠TMout} ) = (i _A -i _R )×|(T _i ) _dmd | (2)

Here, max((T _i ) _{T_ brk ＠TMout} ) represents the maximum target regenerative braking execution amount based on the transmission output shaft, i _A is the target stage gear ratio, i _R is the previous stage gear ratio, and (T _i ) _dmd is the required torque. represents | | is a symbol that represents an absolute value (in the description below, | | is an absolute value symbol in all cases).

Additionally, in equation (2) above, (T _i ) _{T_brk@TMout} represents the target regenerative braking execution amount based on the transmission output shaft.

In the present invention, the hybrid controller 20 may calculate the target regenerative braking execution amount and its maximum value based on the transmission input shaft and transmit it to the brake controller 80. However, as shown in FIG. 5, the hybrid controller 20 calculates the target regenerative braking execution amount and its maximum value based on the transmission output shaft. The target regenerative braking execution amount and its maximum value may be calculated and transmitted to the brake controller 80.

If the target regenerative braking amount based on the transmission output shaft is (T _i ) _{T_brk＠TMout} and the target regenerative braking amount based on the transmission input shaft is (T _i ) _{T_brk} , the two values are '(T _i ) _{T_brk＠TMout} = i _R ×(T _i ) There is a relationship of _{T_brk} '.

The maximum target regenerative braking amount is a value corresponding to the difference in transmission output torque (T _o ) before and after shifting, that is, the amount of decrease in transmission output torque (T _o ) in the AB section, and the previous gear ratio as in equation (2). It can be obtained from (i _R ), target gear ratio (i _A ), and required torque ((T _i ) _dmd ).

Since the time point A is before shifting, only the transmission torque (T _R ) of the release element (release clutch) is applied. This means that when the required torque is (T _i ) _dmd and the previous gear ratio is i _R , the transmission torque (T _R ) can be expressed in the formula 'T _R = i _R × (T _i ) _dmd '.

At point B, the torque transmission of the release element (release clutch) ends and only the transmission torque (T _A ) of the engagement element (engagement clutch) acts. Therefore, when the target stage gear ratio is i _A , the transmission torque of the engagement element (T _A ) can be expressed as 'T _A = i _A × (T _i ) _dmd '.

At this time, the transmission output torque drop amount (|T _A - T _R |) is '|T _A - T _R | _{= |} ( _{i A} -i _R ) The absolute value of the difference between T _A ) (|T _A - T _R |), so it is a positive value.

In addition, since it is a downshift, i _A > i _R is satisfied, so the transmission output torque drop amount (|T _A - T _R |) is '|T _A -T _R | = (i _A -i _R )×|(T _i ) _dmd |'.

To summarize, the transmission torque (T _R ) of the release element before shifting is 'T _R = i _R × (T _i ) _dmd ', and the transmission torque (T _A ) of the coupling element after shifting is 'T _A = i _A × (T _i ) _dmd ', and the transmission output torque (T _o ) drop amount (|T _A -T _R |) is '|T _A -T _R | = (i _A -i _R )×|(T _i ) _dmd |'.

When comparing before and after shifting in the diagram of FIG. 6, the transmission output torque (T _o ) is negative (-) torque, so it decreases (decreases), but when based on the absolute value, it increases.

The transmission output torque drop amount in the above equation is based on the transmission output shaft, and if this is converted into torque based on the transmission input shaft, since the shift gear at this time is the previous gear, the transmission output torque (T _o ) drop amount converted based on the transmission input shaft is '(i _A -i _R )/i _R ×|(T _i ) _dmd |'.

In the present invention, the transmission output torque (T _o ) reduction amount (a positive value) converted based on the transmission input shaft is set to the maximum target regenerative braking amount based on the transmission input shaft. Therefore, the maximum target regenerative braking amount based on the transmission input shaft is as follows. It can be expressed as equation (3).

max((T _i ) _{T_ brk} ) = (i _A -i _R )/i _R ×|(T _i ) _dmd | (3)

Here, max((T _i ) _{T_ brk} ) represents the maximum target regenerative braking amount based on the transmission input shaft, and (T _i ) _{T_ brk} represents the target regenerative braking amount based on the transmission input shaft.

In the diagram of FIG. 6, the target regenerative braking execution amount (T _i ) _{T_brk} based on the transmission input shaft in the AB section increases from a negative (-) value to 0 Nm at a certain slope (decreases based on absolute value) and continues to positive (+). ) (increases based on absolute value), showing that it reaches the maximum target regenerative braking amount (max((T _i ) _{T_ brk} ) based on the transmission input shaft at point B.

In addition, in the AB section of the power-off downshift shift process according to the present invention, a hydraulic braking device is used to generate hydraulic braking torque to simulate engine braking. At this time, the actual hydraulic braking torque is estimated, and the estimated value is the actual hydraulic braking torque. Motor torque feedback control is performed based on the hydraulic braking torque estimate (T _B ).

In this process, the estimated actual hydraulic braking torque (T _B ) and the target hydraulic braking torque ((T _B ) _T ) are similar based on the transmission input shaft, so that the motor torque can compensate for the difference between the two torques.

That is, after the brake controller 80 receives the target regenerative braking amount ((T _i ) _{T_ brk} ) from the hybrid controller 20, the required torque ((T _i ) _dmd ) is calculated according to Equation (1), which is a braking force distribution equation. Determine the hydraulic braking torque ((T _B ) _T ) from the target regenerative braking execution amount ((T _i ) _{T_ brk} ), and use the determined hydraulic braking torque ((T _B ) _T ) as the target value to control the hydraulic braking system. Controls brake hydraulic pressure.

Referring to FIG. 7, the target hydraulic braking torque (hereinafter referred to as 'target hydraulic braking torque') ((T _B ) _T ) is shown as a dotted line, and the actual hydraulic braking controlled to follow this target hydraulic braking torque. The estimated value of the torque amount, that is, the actual hydraulic braking torque estimated amount (T _B ), is shown.

As can be seen in FIG. 7, the control followability of the brake hydraulic pressure is poor, so a difference occurs between the actual hydraulic braking torque estimate (T _B ) and the target hydraulic braking torque ((T _B ) _T ), and in the present invention, this difference is used by the motor. Compensate with torque.

That is, when the brake controller 80 controls the brake hydraulic pressure, it controls to produce the target hydraulic braking torque, but since the control followability of the brake hydraulic pressure is not good, the actual hydraulic braking torque does not come out as much as the target hydraulic braking torque.

Therefore, the error in hydraulic braking is compensated through motor regenerative braking torque control with excellent control accuracy, and the target regenerative braking torque is corrected using the difference between the two torque errors, that is, the target hydraulic braking torque and the estimated actual hydraulic braking torque. After that, motor regenerative braking is controlled using the corrected regenerative braking torque.

Regarding the control for compensating for the difference between the target hydraulic braking torque and the estimated actual hydraulic braking torque as described above with the motor, Patent Application No. 10-2018-0019815 (2018.2.20.) filed by the present applicant, and Please refer to Patent Application No. 10-2017-0177711 (December 22, 2017).

For example, the transmission input torque value such that the sum of the transmission input torque (T _i ) and the estimated actual hydraulic braking torque satisfies the required torque, is used as the target regenerative braking torque (motor regenerative braking execution amount) to generate motor torque (i.e., motor regenerative braking). to control braking torque.

Here, the required torque is the required torque ((T _i ) _dmd ) based on the transmission input shaft, and the actual hydraulic braking torque estimate is the value based on the transmission input shaft.

That is, the actual hydraulic braking torque estimate (T _B@TMin ) based on the transmission input shaft is used, which can be calculated from the actual hydraulic braking torque estimate (T _B ) based on the transmission output shaft.

In FIG. 7, the left side of the vertical axis (y-axis) is the torque based on the transmission input shaft, and the right side is the torque based on the transmission output shaft, with the target hydraulic braking torque ((T _B ) _T ) shown as a dotted line and the actual hydraulic braking shown as a solid line. The torque estimate is the hydraulic braking torque value based on the transmission output shaft.

In other words, when control progresses from point A to point B according to time on the horizontal axis (x-axis), the target hydraulic braking torque ((T _B ) _T ) based on the transmission output axis is a dotted line, and the actual hydraulic braking torque (estimated amount) ( T _B ) is a solid line, and when compensating for the error between the two torques with the motor torque (T _i ), the motor torque command is a command based on the transmission input shaft, so the actual hydraulic braking torque estimate should be considered by comparing it to the transmission input shaft reference torque.

If the sum of the estimated actual hydraulic braking torque based on the transmission input shaft and the motor torque (= transmission input torque, T _i ) is controlled to satisfy the required torque ((T _i ) _{dmd )} based on the transmission input shaft, the control error of the brake hydraulic pressure It is also possible to control it to obtain the desired deceleration feeling.

As described above, at point B, the torque transmission of the release element (release clutch) is terminated and only the transmission torque (T _A ) of the engagement element (engagement clutch) acts. When the target stage gear ratio is i _A , the engagement element The transmission torque (T _A ) can be expressed as 'T _A = i _A × (T _i ) _dmd '.

As can be seen in Figure 7, the actual hydraulic braking torque estimate (T _B ) and the target hydraulic braking torque ((T _B ) _T ) were both 0 Nm up to point A, and then both torques, expressed as negative torques, were AB During the section, it decreases ₍ decreases), that is, increases based on the absolute value, and at this _{time ,} both torques increase to 'T _A = i _A (See T _B and (T _B ) _T in FIG. 6, it decreases as a negative torque and descends in the drawing).

At this time, the target hydraulic braking torque ((T _B ) _T ) linearly decreases at a constant slope up to the transmission torque (T _A ) of the coupling element in the AB section, 'T _A = i _A × (T _i ) _dmd ', However, when controlling the hydraulic braking system during descent, the actual hydraulic braking torque (estimated amount, T _B ) differs from the target hydraulic braking torque ((T _B ) _T ).

_{Here ,} the transmission torque of _{the coupling} element _{, '} T _A = i _A If the actual hydraulic braking torque estimate (T _B ) is converted to the transmission input shaft standard using the required torque ((T _i ) _dmd ) based on the transmission input shaft, it can be similar to T _B@TMin in FIG. 7.

If this is expressed in a formula, '(T _i ) _dmd : T _B@TMin = i _A ×(T _i ) _dmd : T _B ', so 'T _B@TMin = T _B /i _A '.

Here, T _B@TMin is the actual hydraulic braking torque estimate converted based on the transmission input shaft.

Since the brake torque is fully responsible for the braking force that was responsible for the regenerative braking torque by the motor 110, taking this into consideration, the transmission input torque (T _i ), which becomes the motor torque, is 'T _i = (T _i ) _dmd - T _B@TMin = (T _i ) _dmd - T _B /i _A '.

Ultimately, the hybrid controller 20 generates and outputs a torque command corresponding to the motor torque T _i value, and the motor controller 60 controls the motor torque according to the torque command received from the hybrid controller 20.

In addition, the brake controller 80 performs control to increase hydraulic braking torque as the target regenerative braking execution amount decreases, and the shift controller 40 maintains the previous stage clutch state (maintains TC _R ).

Next, the BC section is a speed change section, and is a section in which the transmission input shaft rotation speed (= motor speed, N _M ) is increased to approach the target stage synchronous speed (N _Mj ).

As a condition for entering the speed change section, the absolute value (|T _i |) of the transmission input torque (i.e., motor torque, T _i ) is a smaller value than the predetermined first set torque (|T _i | ≤ first set torque). If the condition of maintaining for a certain period of time is satisfied, the speed change section is entered, where the first set torque can be set to a small value close to 0.

In the example of FIG. 6, the point when the absolute value (|T _i |) of the transmission input torque (T _i ) approaches 0 and satisfies the condition of maintaining the state below the first set torque for a certain period of time is indicated as time point B, At point B when the above conditions are satisfied, the release of the input torque can be considered completed.

Ultimately, as shown in FIG. 5, when the release of the input torque is completed (i.e., the above conditions are completed) and the speed change section (BC section) is entered, the shift controller 40 releases the release element (release clutch) ( Controlled to TC _R = 0), the transmission 120 is converted to a neutral state. Since the coupling element (coupling clutch) is not engaged from point B to point C, the neutral state of the transmission is maintained. You can.

In addition, when entering the speed change section (BC section), the transmission input torque (i.e., motor torque, T _i ) is 0 Nm, so even if the release element is released at once, there is no change in the transmission output torque, making it possible to enter a neutral state. do.

At the same time, the hybrid controller 20 controls the motor speed so that the transmission input shaft rotation speed (N _M ) follows the target stage synchronous speed (N _Mj ) regardless of the required torque ((T _i ) _dmd ).

At this time, the transmission output torque (T _o ) is determined by the hydraulic braking torque, and regardless of this, the motor 110, which is the driving source of the vehicle, can be driven in a neutral state so that the speed changes up to the target stage synchronous speed within a short time.

In addition, since it is in a neutral state, no load torque at the rear end of the transmission 120 is applied at the front end of the transmission 120, so faster control is possible compared to speed control when the clutch transmission torque is applied.

In addition, for cooperative control with the brake controller 80, the hybrid controller 20 sets the target regenerative braking amount to the amount based on the transmission output shaft to satisfy the relationship of 'total braking torque = target regenerative braking amount + hydraulic braking torque'. It is calculated and transmitted with the value of (i _A - i _R )×|(T _i ) _dmd |.

Accordingly, the brake controller 80 generates hydraulic braking torque by performing brake hydraulic control that satisfies the total braking torque based on the target regenerative braking execution amount received from the hybrid controller 20.

Here, the required torque is used as the total braking torque.

Next, the CD section is a synchronization section in which synchronization occurs when the motor speed (N _M ) reaches the target stage synchronous speed (N _Mj ).

As a condition for entering the synchronous section, the absolute value (|N _{Mj - N M |) of the difference between the target stage synchronous speed (N Mj )} and the motor speed (N _M ) is less than or equal to the predetermined set speed (| _{N Mj -} N _M | If the condition of maintaining a small value of (≤ set speed) is satisfied for a certain period of time, it enters the synchronous section, where the set speed can be set to a small value close to 0.

In the example of FIG. 6, the point at which the motor speed (N _M ) approaches the target stage synchronous speed (N _Mj ) satisfies the condition of maintaining the speed difference (|N _Mj - N _M |) below the set speed for a certain period of time. is shown at point C.

When entering the synchronous section, the shift controller 40 controls the engagement of the coupling element (coupling clutch) in the transmission 120 (clutch torque TC _A applied in FIG. 6). At this time, the transmission input torque, which is the motor torque (i.e. Since the transmission input shaft torque (T _i ) is maintained at 0 torque (0 Nm), even if the coupling elements are fastened at once, there is no change in the transmission output torque (transmission output shaft torque) and no sense of acceleration of the transmission output shaft.

At this time, as the coupling element (coupling clutch) is fastened (clutch torque TC _A applied in FIG. 6) as described above, the transmission torque of the coupling element becomes T _A , and this T _A becomes the transmission output torque (T _o ).

In addition, even in the synchronous section, the hybrid controller 20 calculates and transmits the target regenerative braking execution amount as the value of (i _A - i _R ) × | (T _i ) _dmd |, which is the execution amount based on the transmission output shaft, for cooperative control. .

Accordingly, the brake controller 80 generates hydraulic braking torque by performing brake hydraulic control that satisfies the total braking torque based on the target regenerative braking execution amount received from the hybrid controller 20.

Here, the required torque is used as the total braking torque.

Next, the D-E section is a section where cooperative control is performed to restore the transmission input torque after speed synchronization is achieved.

In other words, after the engagement clutch is engaged in the C-D section and speed synchronization is completed, transmission input torque return control is performed from time D, and time E is the time when all shifting is completed.

As an entry condition, if the condition that a set time has elapsed from point C is satisfied, the D-E section is entered, and the set time here can be said to be a waiting time to ensure clutch engagement.

And, as described above, cooperative control is performed to restore the transmission input torque from point D after the predetermined waiting time has elapsed, and at this time, the transmission input torque (T _i ), which is the motor torque, is reduced to the negative torque region ( Performs transmission input torque return control to reapply and restore the torque (increased based on absolute value).

In addition, when the transmission input torque (T _i ) reaches the required torque ((T _i ) _dmd ) based on the transmission input shaft again through cooperative control, the input torque has returned to the required torque level, and the shifting process ends at point E.

Here, as an end condition, the absolute value (|T _i - (T _i ) _dmd |) of the difference between the transmission input torque (T _i ) and the transmission input shaft reference required torque ((T _i ) _dmd ) is a predetermined second set torque. If the condition of maintaining a small value of (|T _i - (T _i ) _dmd | ≤ second set torque) for a certain period of time is satisfied, the transmission input torque return control and shift process are all terminated, where the second set torque can be set to a small value close to 0.

In the example of FIG. 6, the transmission input torque (T _i ) is close to the transmission input shaft reference required torque ((T _i ) _dmd ), and the torque difference (|T _i - (T _i ) _dmd |) is less than or equal to the second set torque. The point in time when satisfies the condition of being maintained for a certain period of time is indicated as point E, which is the end point of shifting.

In the transmission input torque return control section, the shift controller 40 maintains the clutch state in the target stage (maintaining TC _A and T _A states), and the hybrid controller 20 controls the transmission input torque (contrary to the transmission input torque release control section). Motor torque, T _i ) is lowered (increased based on absolute value) to the required torque ((T _i ) _dmd ) based on the transmission input shaft.

In addition, the transmission input torque return control section is different from the transmission input torque release control section in that it is the reverse control, that is, it is a control that lowers the transmission input torque (motor torque, T _i ) to the required torque based on the transmission input shaft. However, there is no difference in the methodological aspect of the cooperative control process performed by the controllers compared to the transmission input torque release control section.

That is, in the D-E section, reverse control of the A-B section is performed, and the hybrid controller 20 calculates the target regenerative braking amount and transmits it to the brake controller 80.

In addition, the hybrid controller 20 makes the actual hydraulic braking torque estimate (T _B ) and the target hydraulic braking torque ((T _B ) _T )) similar to each other based on the transmission input shaft, and the motor torque can compensate for the difference between the two torques. make it possible

At this time, the hybrid controller 20 generates and outputs a torque command for compensation, and the motor controller 60 controls the motor torque according to the torque command output by the hybrid controller 20.

Additionally, the brake controller 80 generates hydraulic braking torque by performing brake hydraulic control that satisfies the total braking torque based on the target regenerative braking execution amount received from the hybrid controller 20.

In summary, as illustrated in FIG. 6, during the transmission input torque return control (see DE section), the motor torque, which is the transmission input torque (T _i ), is changed to a demand determined according to the vehicle driving state (e.g., vehicle speed). Increase based on the absolute value until the torque ((T _i ) _dmd ) is reached.

In addition, during the transmission input torque return control performed when the vehicle is coasting, the hydraulic braking device is controlled to generate hydraulic braking force, and at the same time, the actual hydraulic braking torque estimate (T _B or T _B@TMin ), which is an estimated value of the hydraulic braking torque, is Based on this, the motor torque, which is the transmission input torque (T _i ), is controlled.

In addition, in the process of generating hydraulic braking force as described above, after entering the transmission input torque return control, the target regenerative braking execution amount ((T _i ) _{T_brk} ) is determined, and the vehicle driving state is determined by the total braking torque of the braking force distribution type. Using the required torque determined according to the target hydraulic braking torque such that the sum of the target regenerative braking execution amount and the target hydraulic braking torque satisfies the required torque, the hydraulic braking device is controlled according to the target hydraulic braking torque. This generates hydraulic braking force.

Here, the required torque may be a required torque ((T _i ) _dmd ) based on the transmission input shaft, and both the target regenerative braking amount and the target hydraulic braking torque may be torques determined as values based on the transmission input shaft.

Alternatively _{, the} required torque may be a required torque based on the transmission output shaft ('i _A .

In addition, during the transmission input torque return control, the motor torque is controlled by setting the transmission input torque value as the target value such that the sum of the actual hydraulic braking torque estimate, which is an estimated value of the actual hydraulic braking torque, and the transmission input torque satisfies the required torque. do.

Here, the hydraulic braking torque estimate may be the actual hydraulic braking torque estimate (T _B@TMin ) based on the transmission input shaft.

In addition, the target regenerative braking execution amount ((T _i ) _{T_brk} ) from the time of entering the transmission input torque return control to the completion of the transmission input torque return is determined as a value decreased at a constant slope over time until the required torque is reached. do.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements can be made by those skilled in the art using the basic concept of the present invention as defined in the following patent claims. It is also included in the scope of rights of the present invention.

9: Vehicle wheel 10: Driving information detection unit
20: Hybrid controller (HCU) 30: Engine controller (ECU)
40: Transmission controller (TCU) 50: Battery controller (BMS)
60: Motor controller (MCU) 70: Battery
80: Brake controller (BCU) 90: Engine
100: engine clutch 110: motor
120: Transmission 130: Hydraulic circuit
131: wheel brake

Claims (17)

If the controller determines that there is a request for power-off downshifting due to the driver's downshift operation while the vehicle is coasting, the transmission input torque is released by reducing the motor torque to an absolute value in the negative torque region. performing transmission input torque release control;
When release of the transmission input torque is completed, controlling the release clutch of the transmission to be released by the controller;
In a state in which the release clutch of the transmission is released, the motor speed is controlled by the controller so that the rotation speed of the transmission input shaft reaches the set target stage synchronous speed of the target stage after shifting;
When the transmission input shaft rotation speed reaches the target stage synchronous speed, controlling the coupling clutch of the transmission to be engaged by the controller; and
The controller performing a transmission input torque return control in which the motor torque is increased from a negative torque region to an absolute value and the transmission input torque is reapplied;
It includes, wherein the controller controls the hydraulic braking device to generate hydraulic braking force while the steps are performed, and at the same time controls the motor torque, which is the transmission input torque, based on the actual hydraulic braking torque estimate, which is an estimate of the hydraulic braking torque. A power-off downshift control method for a hybrid vehicle, characterized in that.
In claim 1,
During the transmission input torque release control, the controller reduces the motor torque, which is the transmission input torque, based on an absolute value until it reaches 0 torque.
In claim 1,
In the process of generating the hydraulic braking force,
The controller is,
Determine the target regenerative braking amount, use the required torque determined according to the vehicle driving condition as the total braking torque of the braking force distribution method, and ensure that the sum of the target regenerative braking amount and the target hydraulic braking torque satisfies the required torque. A power-off downshift control method for a hybrid vehicle, comprising determining a target hydraulic braking torque and then controlling a hydraulic braking device according to the target hydraulic braking torque to generate hydraulic braking force.
In claim 3,
The required torque is a required torque based on the transmission input shaft, and both the target regenerative braking amount and the target hydraulic braking torque are torques determined as values based on the transmission input shaft. A power-off downshift control method for a hybrid vehicle, characterized in that.
In claim 3,
The required torque is a required torque based on the transmission output shaft, and both the target regenerative braking amount and the target hydraulic braking torque are torques determined as values based on the transmission output shaft. A power-off downshift control method for a hybrid vehicle, characterized in that.
In claim 1,
During the transmission input torque release control, the controller sets the transmission input torque value to a target value such that the sum of the actual hydraulic braking torque estimate, which is an estimated value of the actual hydraulic braking torque, and the transmission input torque satisfies the required torque determined according to the vehicle driving state. A power-off downshift control method for a hybrid vehicle, characterized in that the motor torque is controlled by.
In claim 6,
A power-off downshift control method for a hybrid vehicle, wherein the required torque is a required torque based on the transmission input shaft, and the hydraulic braking torque estimate is an actual hydraulic braking torque estimate based on the transmission input shaft.
In claim 7,
The actual hydraulic braking torque estimate based on the transmission input shaft is calculated using the actual hydraulic braking torque estimate based on the transmission output shaft and the transmission gear ratio of the target stage after shifting, using the equation 'T _B@TMin = T _B /i _A ' (where T _B@ Power-off of a hybrid vehicle, which is calculated from _(TMin is the actual hydraulic braking torque estimate based on the transmission input shaft, T _B is the actual hydraulic braking torque estimate based on the transmission output shaft, and i _A is the transmission gear ratio in the target stage after shifting) Downshift control method.
In claim 1,
When the vehicle is coasting, a target regenerative braking execution amount is determined by the controller as a required torque determined according to the vehicle driving state until the transmission input torque release control is entered,
The power of a hybrid vehicle, characterized in that the target regenerative braking execution amount is determined by the controller as a value increased by a constant slope over time from the required torque from the time the transmission input torque release control is entered until the transmission input torque release is completed. Off downshift control method.
In claim 9,
The _{controller sets} the target regenerative braking execution amount to the positive maximum value '(i _A -i _R )/i _R (where i _R is the transmission gear ratio of the previous stage before shifting, i _A is the transmission gear ratio of the target stage after shifting, and (T _i ) _dmd is the required torque based on the transmission input shaft) A hybrid vehicle characterized in that it is determined by increasing the value. Power-off downshift control method.
In claim 10,
The power-off downshift control method of a hybrid vehicle, wherein the controller maintains the target regenerative braking execution amount at the maximum positive value from the time when transmission input torque release is completed to the time when transmission input torque return control is entered.
In claim 1,
A power-off downshift control method for a hybrid vehicle, wherein in the step where the engagement clutch of the transmission is controlled to engage, the motor torque, which is the transmission input torque, is maintained at 0 torque by the controller.
In claim 1,
During the transmission input torque return control, the controller increases the motor torque, which is the transmission input torque, on an absolute value basis until it reaches the required torque based on the transmission input shaft determined according to the vehicle driving state. Shift control method.
In claim 1,
During the transmission input torque return control, the controller sets the transmission input torque value to a target value such that the sum of the actual hydraulic braking torque estimate, which is an estimated value of the actual hydraulic braking torque, and the transmission input torque satisfies the required torque determined according to the vehicle driving condition. A power-off downshift control method for a hybrid vehicle, characterized in that the motor torque is controlled by.
In claim 14,
A power-off downshift control method for a hybrid vehicle, wherein the required torque is a required torque based on the transmission input shaft, and the hydraulic braking torque estimate is an actual hydraulic braking torque estimate based on the transmission input shaft.
In claim 15,
The actual hydraulic braking torque estimate based on the transmission input shaft is calculated using the actual hydraulic braking torque estimate based on the transmission output shaft and the transmission gear ratio of the target stage after shifting, using the equation 'T _B@TMin = T _B /i _A ' (where T _B@ Power-off of a hybrid vehicle, which is calculated from _(TMin is the actual hydraulic braking torque estimate based on the transmission input shaft, T _B is the actual hydraulic braking torque estimate based on the transmission output shaft, and i _A is the transmission gear ratio in the target stage after shifting) Downshift control method.
In claim 1,
Characterized in that the target regenerative braking execution amount is determined by the controller from the time the transmission input torque return control is entered until the transmission input torque return is completed as a value reduced by a constant slope over time from the required torque determined according to the vehicle driving state. Power-off downshift control method of hybrid vehicle.

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