并联式混合动力汽车模式切换控制策略研究

并联式混合动力汽车模式切换时离合器会介入传动系统,容易引起较明显的冲击感,是影响整车驾驶舒适性的主要因素。为此,提出了基于离合器双模糊和电机转矩协调的模式切换控制策略。首先建立混合动力汽车模式切换过程的动力学模型,以减小离合器滑磨功为目标,对模式切换时的离合器接合过程进行划分;其次,结合混合动力汽车模式切换的基本要求和驾驶意图,制定离合器双模糊控制策略,分别对滑摩阶段的接合时长和转矩同步阶段的压力变化率进行控制;然后以离合器滑磨功和整车冲击度为优化目标,采用二次型最优控制算法对滑摩阶段的接合压力进行优化,从而获取模式切换过程中离合器的最优接合压力轨迹;在此基础上,通过实时计算离合器传递转矩,根据电机转矩响应快的特点,制定电机转矩协调控制策略;最后,基于某混合动力试验样车,在底盘测功机上分别进行缓加速、中等加速和急加速下的模式切换试验,对所提出的控制策略进行验证。试验结果表明：该策略能较好地反映驾驶人驾驶意图,保证离合器的使用寿命,所产生的整车冲击度均处于合理范围之内,改善了整车模式切换过程中的驾驶舒适性。     

Multi-state control strategy of starting for a wet friction clutch via a fuzzy logic algorithm

Wet multi-plate friction clutches are used in automotive drivelines to transfer torque, change gears, and prevent motion by locking-up components in the transmission. The control strategy of starting is a crucial technology for the application of a wet multi-plate friction clutch in the automotive industry. In this paper, a multi-state fuzzy control strategy for starting is presented and applied to a continuously variably transmission (CVT) powertrain for the validation of this strategy. The operation of the clutch was divided into four states: parking, starting, riding and emergency. The starting state was investigated in detail. A fuzzy algorithm was employed to control the pressure of the hydraulic cylinder acting on the clutch. A distinguishing feature is that the pressure does not increase but decreases to implement smooth starting during the initial period of starting. The rapid-control prototype (RCP) of the wet friction clutch was developed to validate the new control strategy onboard a test vehicle. Based on the experimental results, the multi-state control strategy for a wet friction clutch is a viable candidate for engineering applications.     

P2混动自动变速器的离合器自适应控制

为了解决混合动力系统动力耦合的响应性和舒适性问题，建立混动离合器C0起动发动机过程和并联动力输出模式下的功率流模型。对C0起动发动机的控制过程进行仿真分析，针对C0的起动扭矩和电机的输出扭矩在时间和空间上的匹配问题，提出以换挡离合器的滑摩控制来进行缓冲的策略。为了实现稳定精确的发动机起动控制，消除各自的扭矩控制、液压系统特性的误差，提出C0离合器起动发动机的自适应控制和B1离合器滑摩自适应控制，以换挡离合器滑差和发动机转速的超调量为监控对象，对C0离合器各阶段压力控制参数进行自适应调整，以优化发动机起动过程。研究结果表明：通过换挡离合器的滑摩控制可以很好地解决C0离合器扭矩和电机扭矩的匹配问题，即使在换挡过程中对发动机起动也能保证良好的舒适性，并控制过程时间在1.5 s内；在整车试验过程中，通过对C0压力的自适应调整，发动机转速的超调和起动冲击问题均可以得到有效解决。     

汽车起步过程离合器传递转矩精确计算分析

在分析汽车起步时电控机械式自动变速器的离合器转矩传递过程的基础上,建立了汽车起步时离合器传递转矩、滑磨功和压盘表面温升的精确计算模型;推导出以离合器主、从动盘相对转速和离合器片表面温度为主要影响因素的离合器片摩擦因数的公式;以某一轿车为实例,对其起步时离合器转矩传递特性进行仿真计算。     

Wet Single Clutch Engagement Behaviors in the Dual-Clutch Transmission System

A frictional torque was generated by a lubricated slip contact between a wet clutch pad and a steel separator during a wet clutch engagement. It is necessary to understand the generation of frictional torque to improve the performance of the frictional torque transfer and the durability of the wet clutch system. The analytical modeling of wet clutch torque transfer considers the effects of surface roughness, permeability, the elastic modulus of the frictional material, lubricant viscosity, temperature, etc. Experimental apparatus for wet clutch engagement was designed for the measurement of frictional torque transfer during wet clutch engagement. The experimental results were compared with the analytical results under various operational conditions for the verification of the theoretical analysis to evaluate the performance of the wet clutch system. Some correlations were investigated between the experimental and analytical results. We found that computation by analytical modeling can predict the effects of oil temperature, applied force, and slip speed, as well as engagement period and frictional torque transfer shapes.     

Method for precise controlling of the at shift control system

The shift comfort and efficiency of Automatic Transmission in vehicle are highly influenced by the pressure of the clutch shift control system, especially by the electro-hydraulic clutch subsystem. In this paper, the new design principles of electro-hydraulic clutch systems developed and modeled in detail, the clutch-to-clutch control system is analyzed in three time intervals: oil filled phase, changing phase of clutch torque and synchronous phase of clutch speed. The demand pressures for the engaged clutches calculated in each phase and is precisely built up by using fuzzy slide mode control, the time of hydraulic pressure building-up is very sensitive to the dither current in simulation. All control parameters are optimized by Cosimulation between software Simulink and SimulationX. Finally, the optimal algorithm of the clutch shift control is written into the transmission control unit of a testing vehicle. The testing results show that the suggested control strategy is effective.     

Analysis of the shifting behavior of a novel clutchless geared smart transmission

Conventional geared transmissions use some kinds of clutches to control the power flow from an internal combustion engine to the driveline while shifting gears. However, the shifting performance is seriously affected by the clutch engagement and an unavoidable drop in the torque may occur when the clutch is disconnected. Moreover, wear of the clutch, the need for hydraulic equipment, and the load limit may together aggravate the limits of the clutch system. For this reason, as a novel transmission without a clutch, the clutchless geared smart transmission (henceforth CGST) is proposed by our research team. The CGST controls the power flow in a multiple-input gear-train by controlling the electric motor attached to the planetary gear system. However, no CGST has been realized in an actual vehicle thus far, and the performance has been predicted only theoretically. In this research, we analyzed the achievable performance based on a developed CGST dynamic model with a typical CGST structure. In addition, a CGST gear-shifting algorithm is proposed for use with the dynamic model. From the simulation results, the CGST does not show an abrupt drop in its torque or oscillation while shifting gears due to the absence of a discontinuous power flow. The developed dynamic model can serve as a performance reference for the CGST. Moreover, it can be used as a simulation tool for developing a gear-shifting control logic scheme.     

Engine clutch torque estimation for parallel-type hybrid electric vehicles

This paper mainly focuses on the accurate estimation of the torque transferred through the engine clutch installed between the engine and the drive motor in parallel-type hybrid electric vehicles. The estimation of the engine clutch torque primarily relies on the forward-direction observer which uses the nominal engine net torque information. To overcome the limitation of using the nominal engine torque information that it may not be accurate during the transient states or due to the influence of external disturbance such as the road condition and wind, the forward-direction observer is supplemented by the use of reverse-direction observer which uses the driveline model and wheel speed measurements. In addition, the drive motor torque information is used to calibrate the nominal engine torque during the idle charging state, so that the driveline characteristic unique to parallel-type hybrid electric vehicle can be utilized to increase the estimation accuracy. Finally, the estimation performance of the designed observer is tested via simulation and experiments based on a real vehicle.     

基于扩展状态观测器和滑模控制的双离合器自动变速器起步自适应控制

双离合器自动变速器（Dual Clutch Transmission,DCT）随着服役时间的增加离合器性态会发生变化导致起步性能下降,为降低离合器性态变化对起步性能的影响,提出一种基于扩展状态观测器和滑模控制的DCT起步自适应控制方法。首先,建立DCT起步动力学模型、发动机模型和液压控制系统模型;将DCT起步问题转化为参考轨迹跟踪问题,通过工况识别并利用极小值原理获得了不同起步工况的参考轨迹;在DCT起步动力学模型中将与离合器性态变化相关的项定义为不确定项,设计扩展状态观测器对不确定项进行估计,同时结合自适应滑模控制器,获得了起步发动机转矩和离合器油压的自适应控制率;为了跟踪发动机转矩和离合器油压的自适应控制率,设计了发动机转矩跟踪控制器,同时对液压系统采用了PID闭环控制;通过MATLAB/Simulink平台仿真以及台架试验验证所提出的DCT起步控制方法对离合器性态变化的自适应效果。研究结果表明：所提出的起步自适应控制方法能够有效避免由离合器性态变化导致的起步延时,同时1挡缓起步和急起步的仿真冲击分别减小了53.11%和43.42%,试验起步冲击分别减小了35.66%和30.31%。     

P2结构混合动力系统协同控制

为了提高混合动力各系统的控制效率和响应性,针对P2结构混合动力系统控制对象的特点和整车的功能需求,提出了P2结构混合动力控制系统的构架和所有有效的工作模式,并从整车运行工况和模式转换效率的角度总结了所有有效的工作模式转换真值矩阵。为了满足各节点单元的协同控制要求,提出了P2混合动力控制系统的协同控制构架,约束了各控制单元的主要功能和接口定义,并对多个控制单元之间的复合控制过程进行描述。分析了2种不同动力源在液压控制的混合动力离合器的耦合过程以及混合动力离合器与换挡离合器控制过程重叠时所带来的动力迟滞,对离合器的压力控制和发动机的启动过程时序进行了优化。在不同的控制阶段定义了关键的控制目标,建立发动机扭矩、电机扭矩、混合动力离合器控制压力三者之间的关联。结果表明：发动机、电机、变速器之间通过HCU的协同控制方法能够高效地完成混动工作模式之间的转换。整车试验验证了各系统的系统控制效果,整个模式转换过程的时间为1.5 s,换挡品质和动力响应性满足驾驶需求。     

Observer-based clutch disengagement control during gear shift process of automated manual transmission

A clutch disengagement strategy is proposed for the shift control of automated manual transmissions. The control strategy is based on a drive shaft torque observer. With the estimated drive shaft torque, the clutch can be disengaged as fast as possible without large driveline oscillations, which contributes to the reduction of total shift time and shift shock. The proposed control strategy is tested on a complete powertrain simulation model. It is verified that the system is robust to the variations of driving conditions, such as vehicle mass and road grade. It is also demonstrated that the revised system with switched gain can provide satisfactory performance even under large estimation error of the engine torque.     

Combustion stability analysis during engine stop and restart in a hybrid powertrain

A cycle-resolved analysis system was designed with the specified measurement instruments to investigate the characteristics of combustion stability in a mild gasoline hybrid powertrain. A Fast Response Flame Ionization Detector (FFID), cylinder pressure transducer and engine torque transducer were used to observe both the engine-out THC emissions and engine performance during a brief moment of engine restart. This research aimed to improve combustion stability and was performed by varying the battery State Of Charge (SOC), injection duration and ignition timing. The results indicate that engine combustion tends to be more stable with longer fuel injection durations and advanced ignition timing, while the effect of the battery SOC is negligible. Also, peculiar differences in the catalyst conversion efficiency at the front and rear of the catalyst during engine restart and deceleration were revealed, with the degree of HC oxidation being the suspected cause. This study not only analyzed the engine control and engine-out total hydrocarbon (THC) emission characteristics, but also implemented control strategies that allowed for combustion stability during engine stop and restart operation.     

大功率自动变速器换挡离合器调压控制研究

为了改善大功率自动变速器换挡过程中换挡离合器（含湿式制动器和湿式离合器）油压的调控水平,提高车辆的换挡品质,从结构上在换挡离合器中设计平衡活塞来补偿离合器旋转离心的影响,并在排油回路中增加背压阀以消除活塞腔内空气造成的不确定性。通过对换挡执行系统结构进行分析,分别针对离合器活塞、电液调压过程及离合器滑摩过程进行模型计算,在此基础上,将惯性相的充油调压控制进行拆解,即在转矩相结束时刻初始常量的基础上叠加一阶控制过程,针对换挡过程中系统存在非线性干扰和参数不确定性的特点,结合系统特性的分阶段试验标定,制定了换挡离合器调压过程的滑模控制策略,并基于MATLAB环境对控制策略的正确性和有效性进行仿真分析,最后进行实车试验验证。研究结果表明：无论是制动器充油还是旋转离合器充油,控制策略均能将惯性相持续时间、换挡冲击和滑摩功率损失等控制在合理范围;控制策略具有良好的性能,旋转离合器和制动器都能实现稳健的惯性相调压控制。     

基于扭矩控制的AMT换挡控制策略研究

提出在车辆起步和换挡过程中通过CAN动力网络控制发动机的输出扭矩来改善AMT换挡品质的新方法,制定扭矩控制与离合器接合控制策略,并在装有AMT的某重型商用车上进行试验。试验结果表明,换挡过程中通过控制发动机的输出扭矩并与离合器的接合过程相协调,可显著提高AMT的换挡品质。     

汽车自动变速器锁止离合器控制策略

分析了锁止离合器的典型结构和锁止点的选取，以及采用车速和发动机节气门开度为主要参数，辅之以其他参数，共同确定液力变矩器锁止的控制策略。     

汽车湿式离合器模糊控制

提出一种新的控制湿式离合器传递转矩的方法。通过建立湿式离合器的数学模型并利用该模型控制蓄压器活塞的移动速度来控制油缸压力,进而控制离合器的传递转矩。同时借助模糊控制器设计,利用模糊控制系统实现离合器平稳结合或分离的目的。台架试验及仿真表明该方法可以使离合器油缸的压力以任意速率升高或下降。     

温度对离合器性能影响的分析

离合器作为整车传动系统中不可或缺的零件之一,其故障模式表现形式主要有整车分离不彻底和挂挡困难。文章以某轻型商用车用离合器总成为研究对象,分别在不同温度下(常温、100℃、150℃、200℃、250℃)对其压盘总成及从动盘总成进行检测,分析温度对其性能的影响。通过统计学中的威布尔分布分析法,分析"试验样件"的性能参数,从而找出其故障产生的原因,为后续零件优化提供了依据。     

Computation of surface temperatures and energy dissipation in dry friction clutches for varying torque with time

This paper describes an investigation of the energy dissipated and the surface temperature at any instant of dry friction clutch assuming torque being a function of time during the slipping. The equations of the thermal loads, total energy dissipated and relative velocity between contact surfaces are presented. Two-dimensional axisymmetric heat conduction problem of dry friction clutch is modeled mathematically and solved numerically using the finite element method to determine the temperature distribution during a single engagement assuming uniform wear between the contact surfaces. The comparison is made between temperature field assuming the torque varying with time and when it’s constant with time. Moreover, the effects of slipping time and dimensionless thickness of the pressure plate λ are to be investigated as well.     

具有双离合器的液力变矩器的结构设计

将液力变矩器与机械式自动变速器合理匹配可组成一种新型自动变速系统，其性能接近自动变速器，但成本降低。为该系统设计了具有双离合器(闭锁离合器，换档离合器)的液力变矩器。阐述了该液力变矩器的结构、工作原理及特点。试验结果表明，所设计液力变矩器可支持新型自动变速系统成为现实。     

Quasi-steady-state linearisation of the racing vehicle acceleration envelope: a limited slip differential example

In the motorsport environment, passive limited slip differentials are a well-established means of improving the traction limitation imposed by the open differential. Torque sensing types are highly adjustable, and can alter both the stability and agility of the vehicle in the various cornering phases of a typical manoeuvre. In this paper, an adjustable clutch plate or ‘Salisbury’ differential model is presented, which can significantly alter its torque bias characteristics through adjustments in the drive/coast ramp angle, the number of friction faces and preload. To allow robust evaluation of differential parameter changes on ultimate vehicle performance and handling balance, a unified acceleration or ‘GG’ diagram framework is then described. This builds on traditional GG diagram approaches, by using nonlinear constrained optimisation to define both the vehicle acceleration limits and a ‘feasibility’ region within the performance envelope. By linearising a seven degrees of freedom vehicle model at multiple operating points, eigenvalue and yaw rate response analysis is then used to establish contours of stability and agility throughout the GG envelope. This brings new insights into the way in which handling balance changes below and up to the vehicle's acceleration limits.