Development of a Novel Energy Efficient Magnetic Scroll Air Motor

涡旋空气马达，也被称为涡旋膨胀机，对于气动执行器来说是一个相对较新的概念。其独特的结构具有许多优点，与气缸、叶片式气动马达等传统气动执行器相比，具有更高的能量转换能力。涡旋技术目前主要在空调和制冷压缩机上广泛应用。小巧、安静、高度紧凑的设计符合制冷压缩机的设计要求。涡旋空气马达运行时，运动涡旋在固定涡旋内摆动，可相对于固定涡旋偏心旋转，形成多个密封的月牙室，电机连续周期性运行。最近，这一概念被重新发明，以制造涡旋空气马达(膨胀机)，由于涡旋空气马达的固有优势，涡旋空气马达立即被用于驱动发电机发电。这样的涡旋和发电机组合已经被Energetix Group Plc和Honda等多家公司成功地用于微型热电联产系统(Micro CHP)。微型热电联产用于在住宅供暖的同时发电，并将多余的电能转化为电网。据称，在家中使用热电联产系统，可利用高达95%的可用燃料能源，并可节省20%的燃气费和电费。在热电联产系统中，涡旋空气马达作为驱动力驱动发电机并使热能循环。另一方面，涡旋空气马达可以用于压缩空气储能系统，以解决与可再生能源电力相关的扩散和间歇问题。众所周知，气动马达的不稳定和漏风降低了涡旋的能效。从我们的研究中，我们观察到，在较低的压缩空气供应压力下，例如由排气压缩空气驱动，能源效率将显著降低。这一特性将影响和限制卷轴的许多应用，如回收废气能量、燃料电池和可再生能源发电的储能。在这项提案中，提出了一种提高涡旋能源效率的创造性方法--开发一种磁涡旋，它将使涡旋气动马达能够在较低和可变的气压下工作。该方法的主要特点是利用磁性材料制作螺旋涡旋。磁涡旋空气马达是由涡旋马达内部的永磁体制成的螺旋线组成的。每个涡旋在一个特定方向上被磁化，其方式是两个涡旋的磁场布置由于它们在涡旋空气马达内的位置而彼此相反。对于磁涡旋，提供压缩空气以产生涡旋运动的机械力，磁化的涡旋将在一定位置产生附加力，以驱动移动涡旋沿其设计的移动方向移动。从我们初步的模拟研究来看，提出的磁涡旋将具有以下优点：1)减少漏风；2)提高涡旋的能效；3)使涡旋能够在低压缩空气供应下工作。根据我们的初步分析，与目前的卷轴相比，总的节能幅度可能在20%左右。本文建议通过进一步的仿真研究和制作涡旋样机来实现这一设想。研究内容包括：涡旋的合适材料、涡旋成型材料的磁化方案、动定涡旋的组合、磁场沿涡旋运动轨迹的演化机理、涡旋平稳运行的控制策略、节能量化分析等。

A scroll air motor, also known as a scroll expander is a relatively new concept to pneumatic actuators. Its unique structure features it many advantages as well as higher ability of energy conversion than other conventional pneumatic actuators, such as cylinders, vane-type air motors, etc. The scroll technique is now mainly and widely implemented in air conditioner and refrigeration compressors. The small, quiet, and highly compact design matches the requirement arising from designing refrigeration compressors. When a scroll air motor is running, the moving scroll wobbles inside the fixed scroll and it can revolve eccentrically with respect to the fixed one to form several sealed crescent chambers, and the motor goes successively and periodically. Recently, the concept was re-invented to build scroll air motors (expanders), which are immediately adopted to drive generators for electric power generation because of the scroll's inherent advantages. Such a scroll and generator combination has been successfully used in Micro Combined Heat and Power systems (Micro CHP) by a number of companies, such as Energetix Group Plc and Honda. Micro CHP is used to generate electric power while heating a house and invert surplus electric power to grid. It is claimed that up to 95% of available fuel energy can be used and the people could save 20% of gas and electricity bills by using the CHP system at home. In a CHP system, the scroll air motor serves as a driving force to drive the generator and also circulate the heat energy. On the other hand, the scroll air motor may be used for compressed air energy storage system to solve the problems of diffusion and intermittence associated with renewable resource electricity . It is well noticed that the instability and air leakage of air motor reduces the energy efficiency of a scroll. From our research, we observed that the energy efficiency will be dramatically reduced at lower compressed air supply pressures, for example, driving by exhaust compressed air. This characteristic will affect and limit many applications of the scroll, such as, recycling exhaust energy, fuel cell, and energy storage for renewable power generation. In this proposal, an inventive approach is proposed for improvement of scroll energy efficiency - development of a Magnetic Scroll, which will allow a scroll air motor to work at lower and variable air pressures. The key feature of the proposed approach is to make scroll spirals using magnetic materials. The magnetic scroll air motor consists of spirals made from permanent magnet inside the scroll motor. Each scroll is magnetized in one particular direction in the way that magnetic field arrangements of both scrolls are opposite to each other for their location inside the scroll air motor. For the magnetic scroll, the compressed air is supplied to produce mechanical force for scroll motion and the magnetized scroll will generate extra force at certain positions to drive the moving scroll to moving along its designed moving direction. From our initial simulation study, the following advantages of the proposed magnetic scroll will have: 1) to reduce the air leakage; 2) to improve energy efficiency of the scroll; 3) to allow the scroll to be able to work at a low compressed air supply. The total energy saving compared with the current scroll could be about 20% from our initial analysis. This proposal is to implement the idea by further simulation study and making a prototype of the scroll. A number of issues will be explored in the proposed research, such as, the suitable materials for the scroll, the scheme for magnetizing the scroll shaped material, assembly of the moving and fixed scroll, the mechanism of the magnetic field evolving along the scroll motion trajectory, control strategy for the scroll to get smooth movement, the quantified analysis for energy saving.