Device for pressing orbiting scroll member in scroll type fluid machine

Abstract

A scroll type fluid machine having two scroll members each having an end plate and a spiral wrap formed on the end plate, the scroll members being coupled to each other such that the wraps thereof mate with each other. One of two scroll members being adapted to make an orbitary movement with respect to the other scroll member while being prevented from rotating around its own axis, so as to form at least one working chamber of different pressures between two scroll members. At least two pressing force imparting chambers are formed on the opposite side of the orbitary scroll member to the wrap. The pressing force imparting chambers includes a first chamber which is communicated through a communication passage with at least one of the working chambers which is not materially communicating with a low pressure port and is not at all communicating with a high pressure port of the machine, and a second chamber which is communicated with the high pressure port through a communication passage, so that fluid pressures of different levels are applied to the first and second pressing force imparting chambers so as to produce a force which presses the orbitary scroll member to the other scroll member.