Evaluation of DC motors for clamping force mechanism in an electro-mechanical continuously variable transmission

Continuously variable transmission (CVT) uses a metal pushing V-belt and pulley system to vary its ratio between the transmission’s input and output. Conventionally, the ratio and the belt’s clamping force are adjusted using a hydraulic system. However, during operation, continuous hydraulic pressure is required to ensure that the belt’s clamping force is always sufficient, resulting in a rather significant losses in the CVT. Thus, an electro-mechanical CVT (EM CVT) is proposed, where the hydraulic system is replaced with a power screw system actuated by a DC motor. As a result, the aforementioned losses can be eliminated since the clamping force can be maintained using the self-lock capability of the power screw system. In this paper, the performance of various DC motors are evaluated, in terms of rated torque, size and weight, so that the most suitable one can be determined for application in the EM CVT. Based on the evaluation process, DC motor type D5BLD450-24A-30S from DMKE Motor Co. is selected since it has a rated torque of 1.4Nm (ranked 2nd highest, the highest at 1.8Nm), relatively small size with a length of 107mm (ranked the smallest) and a weight of 3.2kg (ranked 2nd lowest, the lowest at 3.0kg)

PID control of an electro-mechanical friction clutch system

The main contribution of control technology in automotive powertrain system is that, it enables the whole powertrain system to be precisely controlled; thereby, improving the overall vehicle powertrain performance and sustainability. This paper describes a proportional-integral-derivative (PID) controller development for an electro-mechanical friction clutch (EMFC) system for automotive applications especially, those using continuously variable transmission (CVT). Initially, a simulation study was carried out to determine the PID preliminary parameters values derived using the Astrom and Hagglund tuning method with Ziegler-Nichols formula; then, they are manually being fine- tuned experimentally to improve the clutch engagement and disengagement control performance until satisfying engagement and disengagement process are achieved. The results of this work show that the application of Astrom-Hagglund method and Ziegler-Nichols formula is capable of providing a practical solution for obtaining initial parameters of the PD controllers of engagement and disengagement control of the EMFC system. Through optimizing of P and D parameters, the system indicated excellent performances with improvement in terms of percentage overshoot, settling time and a very small steady state error for clutch engagement and disengagement processes

Application of disc spring in clamping force mechanism for electro-mechanical continuously variable transmission

Pulley-based continuously variable transmission (CVT) with metal pushing V-belt (V-belt) offers tremendous potentials in the fuel economy of the car due to its wide and continuous ratio coverage. Nevertheless, the existing pulley-based CVTs in automotive markets use electro-hydro-mechanical (EHM) actuation system to vary its ratio and to provide sufficient clamping force on the V-belt. This, unfortunately, leads to a significant high power consumption from the engine of the car which eventually worsens the car’s fuel economy. To address this issue, researchers introduce electro-mechanical CVT (EM CVT) in which the application of the EHM actuation system is replaced by an electro-mechanical (EM) actuation system. This paper discusses the application of disc spring in clamping force mechanism of EM CVT. The selected disc spring is analyzed and evaluated to prove its workability for CVT’s application. The analysis results indicate that the application of disc spring in clamping force mechanism of EM CVT is possible and it also offers some benefits particularly in term of its compact design

Clamping force adjustment system for a continuously variable transmission

Continuously variable transmission (CVT) with a metal pushing V-belt (MPVB) is a type of transmission that is widely used for automotive application. In this type of CVT, engine torque is transferred to the vehicle’s wheels using the traction between MPVB and the CVT’s pulleys. Therefore, sufficient clamping force from the pulleys to MPVB is required. Conventionally, the clamping force is generated by extracting some of the engine power through an oil pump in a hydraulic actuation system. The oil pump converts the engine power into hydraulic pressure exerted on the CVT pulleys so that MPVB can be clamped accordingly. This process, nevertheless, causes inefficiency in the vehicle’s powertrain system since less power is transmitted to the wheels. To address this issue, this paper describes a design of clamping force adjustment system using screw-thread mechanism

Review of the Methods to Optimize Power Flow in Electric Vehicle Powertrains for Efficiency and Driving Performance

Electric vehicles (EV) are quickly gaining a foothold in global markets due to their zero tailpipe emissions and increasing practicality in terms of battery technologies. However, even though EV powertrains emit zero emissions during driving, their efficiency has not been fully optimized, particularly due the commonly used single-speed transmission. Hence, this paper provides an extensive review on the latest works carried out to optimize the power flow in EV powertrains using multispeed discrete transmission, continuously variable transmission and multi-motor configurations. The relevant literatures were shortlisted using a keyword search related to EV powertrain in the ScienceDirect and Scopus databases. The review focused on the related literatures published from 2018 onwards. The publications were reviewed in terms of the methodologies applied to optimize the powertrain for efficiency and driving performance. Next, the significant findings from these literatures were discussed and compared. Finally, based on the review, several future key research areas in EV powertrain efficiency and performance are highlighted