Patent ID: 7134528
Filing Date: 2006-11-14
Classification: B66B,Y02B

Abstract:
1. A hydraulic elevator, comprising: a hydraulic drive for moving a car; a pressure accumulator; a pressure switch connected for detecting pressure in said pressure accumulator; a pump connected to said pressure accumulator by an accumulator line and connected to said hydraulic drive by a cylinder line for producing a flow of hydraulic fluid between said hydraulic drive and said pressure accumulator for moving the car; a motor connected to said pump and driven by a power regulating unit for driving said pump; a control/automatic regulation unit generating a signal for controlling said power regulating unit; a tank holding a hydraulic fluid; a charging pump driving by an electric motor for charging said pressure accumulator with hydraulic fluid from said tank in response to said pressure switch; a cylinder line stop valve comprising an electrically switchable on-off valve connected between said cylinder line and said pump; an accumulator line stop valve comprising an electrically switchable on-off valve connected between said accumulator line and said pump; a first pressure sensor for detecting a pressure in said cylinder line; and means for varying pressure between said pump and said cylinder line stop valve and between said pump and said accumulator line stop valve when said elevator car is at a standstill such that pressure differences at said accumulator line stop valve and said cylinder line stop valve are substantially eliminatable before opening said cylinder line stop valve and said accumulator line stop valve.