Abstract: In a regulating device for positive-displacement pumps, in particular vane cell and roller cell pumps, a pressure chamber of the pump can be connected with an outlet duct (14) via a bore (13), in which a regulating piston (17) is displaceable against the force of a spring (16). A flow control valve (11) is arranged for regulating a useful flow. In the area of the bore (13) containing the regulating piston (17), the pressure chamber is in continuous connection with a spring chamber (15) of the regulating piston (17) via a bypass duct (18). As a function of the delivery flow of the positive-displacement pump, the regulating piston (17) controls the open cross-sectional surface of a throttle duct (12), which connects the spring chamber (15) with the outlet duct (14). The regulating piston (17) has a control edge (19), by of which the open cross-sectional surface of the throttle duct (12) is reduced during a movement of the regulating piston (17) in the direction toward the spring chamber (15).

Abstract: A variable flow control apparatus for a pump, including a discharge passage communicating with the pump, a variable flow control valve operative to vary a flow of fluid passing through the discharge passage and disposed within the discharge passage, and a flow control circuit cooperative with the discharge passage to permit a predetermined flow of the fluid. A drain valve within the flow control circuit is actuatable in response to a difference between pressures upstream and downstream of the variable flow control valve. The variable flow control valve includes a spool bore communicating with the discharge side of the pump, a spool moveably disposed in the spool bore and a spring unit biasing the spool to increase the opening area of the discharge passage. The spring unit includes first and second springs arranged in series.

Abstract: A vane cell pump with a flow regulating valve (13), upon whose regulating piston (17) the outlet pressure and a spring force act on one side. Between a pressure chamber (1) and an outlet channel (19), an orifice (14) is provided in the control plate (7), the orifice having a frustum protruding into the pressure chamber. The frustum brings about a flow rate dependent on the pump rpm, which flow in the outlet channel (19) acts upon the face end of the regulating piston (17).

Abstract: The invention relates to a displacement pump, e.g. a vane cell pump, with a flow control valve (13) on the control piston (22) which acts on the pump pressure on the one hand and the consumer pressure taken via a choke device on the other. The control piston (22) acts as a pressure controller in which the pressure difference as the pump speed rises acts as a measure of the adjusted quantity conveyed. The choke device for setting the pressure difference contains a throttle piston (17) movable against the force of a spring (16) in a piston bore (15), which closes off an aperture (14) on the pressure side in a control plate (7) in the basic position. According to the invention, the piston bore (15) has a by-pass channel (18) which continuously connects the pump with a spring chamber (15A) in the throttle piston (17).