PISTON FOR COMPRESSOR, COMPRESSOR AND HEAT PUMP UNIT

PROBLEM TO BE SOLVED: To provide a piston for compressor, a compressor and a heat pump unit, capable of reducing a re-expansion gas amount in a compressor to improve re-expansion and re-compression loss, and also suppressing deterioration of heat insulation efficiency.SOLUTION: A piston for compressor related to at least one embodiment, includes a piston body part having a top surface, which forms a compression chamber configured to compress gas together with a cylinder; and a projection provided so as to project from the top surface along an axis direction of the piston body part. The projection is formed so that a dimension in a direction orthogonal to the axis direction becomes smaller toward the tip of the projection, wherein a cross section along the direction orthogonal to the axis direction is formed into a circular shape. A connection part to the top surface in the projection has a diameter gradually contracting from the top surface toward the tip of the projection, and has a cross section along the axial direction turned into a concave curve.SELECTED DRAWING: Figure 5 【課題】圧縮機の再膨張ガス分を減少させ再膨張・再圧縮損失が改善しつつ断熱効率の低下を抑制できる圧縮機用ピストン、圧縮機及びヒートポンプユニットを提供する。【解決手段】少なくとも一実施形態に係る圧縮機用ピストンは、シリンダとともに気体を圧縮する圧縮室を形成する頂面を有するピストン本体部と、前記ピストン本体部の軸方向に沿って前記頂面から突出するように設けられる突部と、を備え、前記突部は、前記軸方向と直交する方向の寸法が前記突部の先端に向かうにつれて小さくなるように形成され、前記軸方向と直交する方向に沿った断面形状が円形であり、前記突部のうち前記頂面への接続部は、前記頂面から前記突部の先端に向かって徐々に縮径して前記軸方向に沿った断面が凹状の曲面となる。【選択図】図５