The oil power pack is a stand-alone hydraulic device that converts initial (fuel) energy into the outlet pressure of the fluid flow.
The oil hydraulic power pack can be supplied with fuel energy of one or even more types:
- mechanical,
- electrical,
- chemical.
All depends on selection of a booster motor.
Main assemblies and components
A classical power pack of an oil pump has the following:
- A primary motor that can be operated electrically, hydraulically, pneumatically, by petrol (internal combustion engine), or by diesel fuel (internal combustion engine). Its target purpose is to convert energy of the relevant type into energy of load motion (translational or rotational).
- A hydraulic pump, which transforms translational or rotational kinetic energy into mechanical energy of the oil mixture. Based on the required output performances and structural design features of the system, gear, rotary-vane, or plunger types of hydraulic pumps can be used.
- A hydraulic tank, to store the liquid mixture. &mdash The tank is made of metal or plastic. It has a fuel filling neck with a removable filter.
- A pipeline. As is known, the oil moving under pressure gives energy to an actuating element and to the hydraulic motor. The oil flows under a high pump pressure through some fuel passages to the actuating element and flows back to the hydraulic tank through other fuel passages. The pipeline is assembled of steel pipes using assembly joints and parts. It connects all the elements of the system, including hydraulic automation equipment – distribution, control, and monitoring devices.
- A return filter, which purifies the oil mixture that returned to the service tank.
Considering the purpose, oil pump power packs can be supplemented by the structural elements as follows:
- a suction filter, which purifies the oil sucked under by the pump from the hydraulic tank,
- a pressure filter, through which the oil flows through the supply passage to the pump,
- pressure control valves in the pipeline and its circuit arms,
- oil flow control valves in the pipeline,
- directional valves for the work flows in the system and its circuits,
- a hydraulic accumulator (HA), which can be a weight-loaded, spring-loaded, or gas-charged one.
By accumulating the potential energy of a weight (weight-loaded HA), a compressed spring (spring-loaded HA), or compressed gas (gas-charged HA), the accumulator gives it away to the system without switching the pressure pump on. The accumulator keeps the system functional when accidents occur, compensates for leaks and suppresses surges and water hammers.
- a heat exchanger, which prevents the oil mixture from overheating; the oil cooler can operate on the water or air basis,
- a tubular heating element installed in the hydraulic tank; the tubular heating element heats the oil to the working temperature,
- a pointer or electronic pressure gauge, to record the head at control points of the hydraulic system,
- transducers, which measure the pressure, temperature, flow rates of the power fluid mixture in the hydraulic tank as well as filter contamination levels,
- electromechanical relays, to record the fluid level and pressure in the system—once these parameters reach the required values, a controller closes or opens the electric wiring, &mdash
- a mechanical or touch-screen control panel with devices and indicators; the control panel can be fastened on the power pack proper or be distanced from it, and
- a manual or foot-operated control panel connected to the power pack via a cable or a radio channel.
An angular impulse going from the initial motor is transferred via a shaft coupling to the hydraulic pump. The latter sucks the oil from the service tank and feeds it through the pipeline to a distribution zone from where the oil fluid under a high pressure and under hardware check goes to the actuating element to set it in motion. Upon completion of the direct cycle, the oil is drained back to the hydraulic tank.
Technical specifications to be paid attention to when selecting the equipment:
- rated pressure (MPa); it should be considered that only a high-pressure oil power pack can operate under a high load,
- standard pump fluid supply (L/min),
- payload capacity of the hydraulic tank (the maximum volume of oil in the tank) (L),
- power of hydraulic drive (booster) motor (kW or h.p.).
Classification of oil power packs based on main criteria
- By the structure type:
- a monobloc fixed plant supported by a housing frame or legs, e.g., an oil power pack for a press,
- a monobloc mobile power plant equipped with carrying handles, slinging eye bolts, skids, wheels, etc.,
- a stationary hydraulic pump module, which will be installed unit by unit in a dedicated room or mounted on the housing of the operating equipment,
- a self-propelled hydraulically driven device with a chassis.
- By the driving device of the booster motor: it can be driven hydraulically, electrically, pneumatically, by petrol (internal combustion engine), or by diesel fuel (internal combustion engine).
- By the standard pressure in the system and at the outlet: low (less than 16 MPa), medium (less than 40 MPa), high (less than 150 MPa), and ultra-high (above 150 MPa).