Hydraulic pumps are used to store and transfer energy from a higher pressure area to a lower pressure area by means of a liquid PCTE. Hydraulic pumps can be used in a variety of applications ranging from manufacturing processes, automotive and ships, among many others. There are two main categories of hydraulic pump control, namely: variable displacement pumps and constant speed pumps.
Variable displacement pumps are hydraulic pumps in which the speed of flow and the output pressure can be adjusted either by controlling the displacement of the pump or by varying the applied pressure. This type of pump is often referred to as a ‘fluid torque converter’ and uses the mechanical principles of a conventional torque converter system to regulate the speed and pressure of the pump. Variable displacement pumps are typically used in situations where a precise level of control is required, such as in aircraft and automotive applications.
The most common type of variable displacement pump is the VAR-3 pump. This pump utilizes a three-way valve to control the displacement. The valve is operated by a solenoid, and when activated, the solenoid moves the valve from a sealed position to one that allows fluid to flow freely. The amount of fluid allowed to flow is dependent on the displacement setting, which is set manually.
The constant speed pump is used for applications where the flow rate is constant and does not require variable control. This type of pump is typically found in applications where the priority is to efficiently transfer fluid, such as in hydraulic systems for construction machines or oil refineries.
The constant speed pump consists of a fixed plunger which acts as a pressure regulator, and a constant-speed hydraulic motor driving the pump. The motor is connected to a rotor which drives the plunger in a reciprocating motion in order to maintain the constant output pressure. The plunger also acts as a pressure regulator, reducing the pressure as the output flow rate increases. The constant speed pump is better suited for applications where energy transfer efficiency is priority and variable speed control is not required.
Variable speed pumps and constant speed pumps are the two main categories of hydraulic pump control. As such, they each have their own advantages and disadvantages, depending on the application. Variable displacement pumps offer improved accuracy and precise control over the flow rate, but may have lower efficiency in terms of energy transfer. Constant speed pumps may be more efficient in terms of energy transfer but are not suitable for applications where variable control of the pressure or speed is required.
