| 摘要 |
<p>A speed control device is provided for a pneumatic power tool which includes a housing with a pressure air inlet, an output spindle, and an air turbine with a turbine wheel drivingly connected to the output spindle. Nozzles are arranged for directing motive air onto the turbine wheel. The speed control device includes a valve unit for controlling pressure air flow through the nozzles in response to a speed responsive parameter. The plurality of nozzles are divided into n separate nozzle groups having individual air feed through individual air feed passages (n is an integer, n>1). The valve unit is capable of being actuated into n states for controlling air feed to the n nozzle groups, whereby for each subsequent state, x (1≦̸x≦̸n, x is an integer) air feed passages are connected to the pressure air inlet such that nozzle groups 1 to x are fed with air.</p> |
