Control device for positive displacement pumps
A control device for a positive displacement pump includes a throttle device and a flow control valve. The flow control valve includes a flow control piston and is configured to regulate an unrequired excess flow of the pump at an increased speed. The throttle device is configured to produce a speed-related pressure differential in a bore section, the pressure differential being responsible for the displacement of the flow control valve and the throttle device. The throttle device is arranged in the pressure outlet (bore section) of the pump and includes a regulating pin connected to the flow control piston, having a control contour configured so that a modifiable through cross-section is created in association with a throttle bore. The control pin has a wider section in an axial displacement area of the throttle device, the area not being involved in control of the volume flow, whereby a minimum obturating section arises in the displacement area. This may result in accelerated movement of the flow control piston, which may result in quicker reaction of the control mechanism, thereby preventing an overshoot and overincrease in the flow capacity.
1. A control device for a positive displacement pump, comprising:
a throttle device configured to connect a pressure space of the pump to an outlet connected to a consumer; and
a flow control piston displaceably arranged in a housing bore, the flow control piston including a first end face connected to the pressure space and a second end face configured to delimit a space connected to the outlet, the flow control piston configured to open a connection from the pressure space to an inlet duct of the pump in accordance with a differential pressure acting on the first end face and the second end face;
wherein the throttle device is arranged in a pressure output of the pump and includes a control pin, having a control contour configured to cooperate with a throttling bore to define a modifiable passage cross-section, a first one of the control pin and the throttling bore connected to the flow control piston, a second one of the control pin and the throttling bore fixed in relation to the housing; and
wherein the throttle device includes an axial displacement region not used for volume flow control having a thickened portion so that a minimal aperture cross-section is arranged in the axial displacement region.
2. The control device according to claim 1 , wherein the positive displacement pump includes a vane cell pump.
3. The control device according to claim 1 , wherein the control pin is connected to the flow control piston, the throttling bore fixed in relation to the housing.
4. The control device according to claim 3 , wherein the thickened portion of the control pin includes a cylindrical contour and is arranged on the first end face of the flow control piston.
5. The control device according to claim 3 , wherein the thickened portion of the control pin includes a frustoconical contour, a larger diameter of a cone frustum arranged on the first end face of the flow control piston.