A method for shift control without power interruption for a p4 configuration hybrid vehicle

Abstract

The application provides a power interruption-free gear shifting control method for a P4 configuration hybrid vehicle, aiming at overcoming the power interruption problem in the gear shifting process of a P4 hybrid power system. The control method comprises the following steps: S1, selecting a power interruption-free gear shifting control permitted working mode; S2, performing power interruption-free gear shifting control condition judgment; S3, calculating a motor torque compensation amount in the gear shifting process; and S4, determining a motor torque compensation change amount limiting threshold. The application can effectively eliminate the system power interruption phenomenon in the gear shifting process of the P4 hybrid vehicle, and further improve the smoothness and power performance of the vehicle in driving. The method promotes the vehicle to further rely on the motor for power driving and compensation in the driving process, thereby ensuring that the power battery has more energy storage space for the potential next brake recovery, fully utilizing the power redundancy driving characteristics of the P4 hybrid vehicle, and improving the comprehensive quality of the P4 hybrid vehicle.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hybrid vehicle control, in particular to a no-power interruption shift control method for P4 configuration hybrid vehicle. BACKGROUND

[0002] The driving condition of traditional commercial vehicles is complex, and the vehicle mass changes greatly. In order to improve the passability and power performance of the vehicle on bad roads such as mountain muddy roads, wet and slippery roads and ice and snow roads, most commercial vehicles use all-wheel drive. However, the parasitic power generated by all-wheel drive will reduce the economy of the vehicle. P4 hybrid vehicles usually use engine and motor to drive one axle separately, which has the characteristics of power redundancy driving, can realize timely all-wheel drive, and can realize brake energy recovery. It not only can meet the power performance and passability demand of the vehicle in low adhesion condition, but also can improve the economy of the vehicle. However, during the shift process of P4 hybrid vehicle, power interruption similar to traditional fuel vehicle will occur, which not only affects the power demand, but also produces impact feeling. Therefore, it is necessary to develop a no-power interruption shift control method for P4 hybrid vehicle.

[0003] At present, there are few invention patents related to no-power interruption shift control of P4 configuration hybrid power system in the prior art. For example, the invention patent with publication number CN111120644A disclosed on May 8, 2020, a no-power interruption shift control method and system for hybrid vehicle, the invention patent proposes a method for dynamic coordination control during the shift process of hybrid vehicle, which realizes no-power interruption shift by controlling the output torque of the motor. However, this method is not suitable for P4 hybrid vehicle with power redundancy characteristics, and does not involve torque compensation limit threshold, which cannot guarantee that torque mutation does not occur during torque compensation process, thereby affecting the smoothness of driving process, and the actual application value is poor. Another invention patent with publication number CN112145634A disclosed on December 29, 2020, no-power interruption shift of pure electric two-gear transmission, the invention patent realizes no-power interruption shift by optimizing the structure of the transmission, which can save space layout and improve the smoothness of the vehicle. However, the application transplantation is poor, and cannot solve the vehicle object involved in the present invention patent. Therefore, the no-power interruption shift process realized by the above invention patents does not have reference value for P4 hybrid vehicle research object. SUMMARY

[0004] To address the shortcomings of existing technologies, this invention presents a power-interruption-free shift control method for P4 hybrid vehicles. This method fully utilizes the multiple power sources, power-ground coupling characteristics, and rapid motor response of P4 hybrid vehicles to effectively eliminate significant power interruptions during shifting, improving vehicle dynamics and smoothness. Furthermore, the method encourages the vehicle to rely more on the motor for power drive and compensation during driving, thereby ensuring that the power battery has more energy storage space for potential regenerative braking. This fully leverages the power redundancy of P4 hybrid vehicles, enhancing their overall quality.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] 1. A method for power-interruption-free gear shift control in a P4 configuration hybrid vehicle, characterized by comprising the following steps:

[0007] Step 1: Determine the permissible operating mode for gear shifting without power interruption coordination control.

[0008] For a P4 hybrid vehicle, the front axle is driven by an engine and the rear axle is driven by an electric motor. The engine power is transmitted to the front axle and the middle axle through a multi-speed automatic transmission. When the P4 hybrid vehicle is working in three driving modes, namely engine direct drive, vehicle charging, and combined drive, there is a power interruption during the shifting process of the middle axle transmission mechanism. When the P4 hybrid vehicle is working in the vehicle charging mode, the torque demand response of the drive motor is negative. In order to avoid the positive and negative jump of the working torque of the drive motor, the working modes that allow for shifting control without power interruption are selected as engine direct drive and combined drive.

[0009] Step two: Determine the conditions for coordinated control of power interruption during gear shifting.

[0010] P4 hybrid vehicles perform uninterrupted shift control when all of the following conditions are met: the vehicle controller receives a hard-wired signal indicating that the pure fuel mode switch is disabled; the vehicle speed is higher than the minimum stable speed for engine start-up; the state of charge (SOC) signal value of the power battery is higher than the permissible uninterrupted shift coordination control lower limit value of the power battery SOC; and the feedback signal from the central axle transmission control unit indicating that the central axle transmission mechanism is in the shifting process is valid. Otherwise, uninterrupted shift coordination control is not performed or is discontinued.

[0011] Step 3: Calculate the torque compensation amount of the drive motor during the gear shifting process.

[0012] In the unpowered interrupt shift control allowable working mode, a part of the engine output energy meets the power demand of the vehicle running, a part of the engine output energy provides energy for the fan, water pump and other vehicle related accessories, and the engine itself must also maintain an idle state. If only the actual engine torque T eng_real is used as the engine output torque T eng , the motor compensation torque T Com will be too small or even negative. To avoid this, the method uses the actual engine torque T eng_real and the engine requested torque T eng_ask to calculate the motor compensation torque T Com in the shift process, as shown in equation (2).

[0013] T com = T ask -T eng ....................................................(1)

[0014] T eng = δ·T eng_real +(1-δ)·T eng_ask .....................................(2)

[0015] In the equation, T ask is the total demand torque of the vehicle running, δ is the power regulation proportionality coefficient of the engine in the shift process, and the value of δ continuously changes in the duration of the entering shift process, which is determined according to the calibration test.

[0016] Step four, calibrate the amplitude threshold of the driving motor torque compensation change amount,

[0017] According to step three, the motor torque compensation amount T Com in the shift process is solved. To prevent the deterioration of the running smoothness in the compensation process, the method limits the change rate of the compensation amount to prevent torque mutation in the compensation process, and introduces the current actual torque T mot_real of the motor feedback to calculate the demand motor torque compensation change amount ΔT com of each step, as shown in equation (3).

[0018] ΔT com = T com -T mot_real ................................................(3)

[0019] If ΔT comToo large, the P4 hybrid vehicle generates strong longitudinal impact, poor ride, if ΔT com Too small, the power interruption phenomenon of the shift process still can not be completely eliminated, therefore the motor torque compensation change is limited, ΔT com The maximum compensation amount ΔT max And the minimum compensation amount ΔT min Within the range, as shown in equation (4),

[0020] ΔT min ≤ΔT com ≤ΔT max ..............................................(4)

[0021] In the formula, ΔT max , ΔT min The specific value is determined according to the actual calibration test.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] 1. The P4 hybrid vehicle shift control method without power interruption can effectively eliminate the phenomenon of obvious system power interruption during the shift process, thereby improving the power and smoothness of the vehicle driving, and at the same time ensuring that the vehicle power output meets the driving requirements of the driver;

[0024] 2. The P4 hybrid vehicle shift control method without power interruption can realize that the motor is preferentially used for power driving and compensation during vehicle driving, thereby ensuring that the power battery has more energy storage space for potential brake energy recovery, and improving the fuel economy of the vehicle; BRIEF DESCRIPTION OF DRAWINGS

[0025] The description of the embodiments will become easy to understand in combination with the drawings, in which:

[0026] Figure 1 The P4 hybrid vehicle power system structure according to the embodiment of the present application;

[0027] Figure 2 The P4 hybrid vehicle shift without power interruption coordination control flowchart according to the embodiment of the present application.

[0028] Figure 1The winning number explanation: 1- front axle steering wheel, 2- power domain controller, 3- middle axle drive wheel, 4- rear axle drive wheel, 5- drive motor, 6- rear axle two-speed automatic transmission, 7- main reducer and differential assembly, 8- power battery, 9- main reducer and differential assembly, 10- universal joint, 11- middle axle twelve-speed transmission, 12- engine. DETAILED DESCRIPTION

[0029] The embodiments of the present application are described in detail below with reference to the accompanying drawings, wherein the same or similar components are denoted by the same or similar reference numerals throughout. The embodiments described below by reference to the accompanying drawings are exemplary and are for the purpose of explanation only, and are not to be understood as limiting the present application.

[0030] A hub hydraulic hybrid vehicle shift power interruption coordination control method is described below with reference to the accompanying drawings, but the present application is not limited to these embodiments. With reference to the accompanying drawings, Figure 2 , the present application includes the following four key steps:

[0031] Step one, shift power interruption coordination control permission mode judgment,

[0032] With reference to the accompanying Figure 1 , a P4 configuration oriented hybrid vehicle, the front axle of the vehicle is driven by an engine, and the rear axle is driven by an electric motor. The engine power is transmitted to the front axle and the middle axle through a multi-speed automatic transmission. When the P4 hybrid vehicle is driven in engine direct drive, driving charging and combined drive modes, there is a power interruption during the shift process of the middle axle transmission mechanism. When the P4 hybrid vehicle is working in the driving charging mode, the response of the drive motor demand torque is negative. In order to avoid the positive and negative jump of the drive motor working torque, the selected power interruption free shift control permission working mode is engine direct drive and combined drive;

[0033] Step two, shift power interruption coordination control condition judgment,

[0034] The P4 hybrid vehicle performs power interruption free shift control when all the following conditions are met: the vehicle controller receives a hard-wired signal that the pure fuel mode switch is not enabled, the vehicle speed is higher than the minimum stable vehicle speed for engine starting, the power battery state of charge SOC signal value is higher than the allowable power interruption coordination control power battery state of charge SOC lower limit value, and the middle axle transmission mechanism control unit feedback that the middle axle transmission mechanism is in the shift process. The flag signal is valid; otherwise, do not perform or exit the shift power interruption coordination control;

[0035] Step three, calculate the drive motor torque compensation amount during the shift process,

[0036] In the unpowered interrupt shift control allowable working mode, a part of the engine output energy meets the power demand of the vehicle running, a part of the engine output energy provides energy for the fan, water pump and other vehicle related accessories, and the engine itself must also maintain an idle state. If only the actual engine torque T eng_real As the engine output torque T eng , the motor compensation torque amount T Com will be too small or even negative. To avoid this situation, the method combines the actual engine torque T eng_real and the engine requested torque T eng_ask to calculate the motor compensation torque T Com in the shift process, as shown in equation (2).

[0037] T com = T ask -T eng ......................................................(1)

[0038] T eng = δ·T eng_real +(1-δ)·T eng_ask .....................................(2)

[0039] In the equation, T ask is the total demand torque of the vehicle running, δ is the power regulation proportionality coefficient of the engine in the shift process, and the value of δ continuously changes in the duration step after entering the shift process and is determined according to the calibration test.

[0040] Step four, calibrate the amplitude threshold of the driving motor torque compensation change amount,

[0041] According to step three, the motor torque compensation amount T Com in the shift process is solved. To prevent the driving smoothness from deteriorating in the compensation process, the method limits the change rate of the compensation amount to prevent torque mutation in the compensation process. The current actual torque T mot_real of the motor is introduced to calculate the demand motor torque compensation change amount ΔT com of each step, as shown in equation (3).

[0042] ΔT com = T com -T mot_real ...............................................(3)

[0043] If ΔT comToo large, resulting in P4 hybrid vehicle generates strong longitudinal impact, poor ride, if ΔT com Too small, power interruption phenomenon still can not completely eliminate the shift process, so the motor torque compensation change limit processing, ΔT com Located in the maximum compensation ΔT max And the minimum compensation ΔT min The range, as shown in equation (4),

[0044] ΔT min ≤ΔT com ≤ΔT max ..............................................(4)

[0045] In the formula, ΔT max , ΔT min The specific value is determined according to the actual calibration test.

Claims

1. A P4 configuration oriented hybrid vehicle shift control method without power interruption, characterized by, The method comprises the following steps: Step one, judging the working mode of the shift power interruption coordination control, For a P4 configuration hybrid vehicle, the front axle is driven by an engine, and the rear axle is driven by an electric motor. The engine power is transmitted to the front axle and the middle axle through a multi-gear automatic transmission. When the P4 hybrid vehicle works in engine direct drive, driving charging and joint drive modes, there is power interruption during the shifting process of the middle axle transmission mechanism. When the P4 hybrid vehicle works in the driving charging mode, the response of the driving motor demand torque is negative. In order to avoid the positive and negative jump of the working torque of the driving motor, the working mode of the shift power interruption control permission is selected as the engine direct drive and the joint drive. Step two, judging the shift power interruption coordination control condition, When the P4 hybrid vehicle meets all the following conditions, the shift power interruption control is performed: the vehicle controller receives the hard-wired signal that the pure fuel mode switch is not enabled, the driving speed is higher than the minimum stable speed of the engine starting driving, the power battery state of charge SOC signal value is higher than the allowable power battery state of charge SOC lower limit value, and the middle axle transmission mechanism control unit feedbacks that the middle axle transmission mechanism is in the shifting process; otherwise, the shift power interruption coordination control is not performed or exited. Step three, calculating the driving motor torque compensation amount during the shifting process, In the no-power interrupt shift control allowable working mode, a part of the engine output energy meets the power requirement of the vehicle running, a part of the engine output energy provides energy for the vehicle related accessories, and at the same time, the idle state of the engine itself must be maintained. If only the actual engine torque T eng_real is used as the engine output torque T eng , the motor compensation torque T Com in the shift process will be too small or even negative. In order to avoid this situation, the method combines the actual engine torque T eng_real with the engine requested torque T eng_ask to calculate the motor compensation torque T Com in the shift process, as shown in formula (2). （1） （2） In the formula, T ask is the total demand torque of the vehicle, is the power regulation proportion coefficient of the engine during the shift process, the value of the number continuously changes in the duration step after entering the shift process, and is determined according to calibration test; Step four, limiting the amplitude threshold of the driving motor torque compensation change amount, According to step three, the motor torque compensation amount T is solved Com To prevent the ride comfort from deteriorating during the compensation process, the method limits the change rate of the compensation amount to prevent torque from suddenly changing during the compensation process, and introduces the motor to feed back the current actual torque T mot_real The motor torque compensation change amount ΔT is calculated for each step com As shown in equation (3), （3） The motor torque compensation change amount is limited, ΔT com located within the maximum compensation amount ΔT max and the minimum compensation amount ΔT min range, as shown in equation (4), （4） where ΔT max , ΔT min The specific values are determined by actual calibration tests.

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