Coil of joy
The Coil of Joy (དགའ་འཁྱིལ་, Wyl. dga' khyil) is a disc divided into three or four sections by arcs of different colours and joining in the centre. The Tibetan term dga' means joy, delight or pleasure, while 'khyil means to circle or spin. The coil of joy is usually drawn in the central hub of wheels of dharma. The three or four swirls can represent the Three Jewels and victory over the three poisons, or the Four Noble Truths and the four cardinal directions. In Dzogchen its three swirls of the symbolize the gorund, path, and fruition.
Robert Beer, The Handbook of Tibetan Buddhist Symbols (2003) p.209.