| abstract |
A coffee maker having a heating device for heating water to the temperature necessary for producing a coffee drink. The coffee maker is equipped with an electrically powered pump for the delivery of water, with a bore being provided in the pump casing. Within the bore, a working piston reciprocates, its stroke determining a working chamber. The coffee maker is provided with a suction valve and a discharge valve, each including a valve closure body spring-loaded in the closing direction. The suction valve is opened by pressure below atmospheric and the discharge valve by pressure above atmospheric in the working chamber. The preparation of the coffee drink is accomplished by the pump drawing water through the suction valve and delivering it under pressure through the discharge valve to a brewing chamber adapted to be filled with coffee grinds from which it escapes following extraction. The pump draws hot water which is already preheated by the heating device to the temperature suitable for preparing the brew, with the suction valve being configured as a poppet valve. As a result, brewing water heated to a practically constant temperature is supplied to the material, irrespective of the firmness to which the coffee grinds are compressed and the fineness of the grind, and also irrespective of the quantity of coffee or espresso to be made, with the hot water being pumped to the brewing chamber without an appreciable drop in pump capacity occurring. |