Overload protective device for an internal combustion engine acting as a drive motor of a main pump of a hydraulic pressure generator

摘要

An overload protection device for a drive motor of a pressure generator is provided including an auxiliary pump, flow resistance devices, and a pressure-controlled valve. The drive motor drives the main pump of the pressure generator, whose output flow rate is stabilized by a hydraulic regulating valve, which senses the pressure of the output flow of the main pump. The auxiliary pump is also driven by the drive motor and generates an output flow rate proportional to the rotational speed of the drive motor. An auxiliary hydraulic circuit, including the first and second flow resistance devices connected in series, connects the auxiliary pump to the tank of the hydraulic pressure generator. The pressure-controlled valve includes a control chamber connected with a tapping point in the auxiliary hydraulic circuit for sensing the output flow of the auxiliary pump. The pressure-controlled valve is connected with the regulating valve of the hydraulic pressure generator such that if the rotational speed of the drive motor falls below a threshold value, the regulating valve is relieved of a comparison pressure from the main hydraulic circuit connected to the main pump, which will cause the delivery volume of the main pump to be reduced to a minimum delivery level, preventing the drive motor from being stalled.