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A rotating oscillating hydraulic cylinder, also known as a rotating oscillating hydraulic motor, utilizes hydraulic pressure to generate very high torque in a very small space. It is an actuator that outputs torque and achieves reciprocating motion, capable of reciprocating swinging motion within a range of less than 360 degrees.
01. Vane type rotating oscillating hydraulic cylinder
Oscillating hydraulic cylinders typically come in two structural types: vane-type and screw-type. Vane-type oscillating hydraulic cylinders are characterized by a fixed internal device called a vane. One vane segment is securely fastened to the outer casing, while the piston is securely fastened to the drive shaft. Vane-type oscillating hydraulic cylinders are extremely compact, with a maximum rotation angle of 270 degrees.
Oscillating hydraulic cylinder operating principle: When pressurized oil flows into one port of the hydraulic cylinder and returns to the other, the vane oscillates in one direction under the pressure of the oil, driving the shaft to deflect by a certain angle, less than 360 degrees. When the inlet and return ports are swapped, the motor reverses.
Vane swing rotating oscillating hydraulic cylinders are divided into single-vane and dual-vane rotating oscillating hydraulic cylinders. The single-vane rotating oscillating hydraulic cylinder consists primarily of a stator block 1, cylinder body 2, swing shaft 3, vanes 4, left and right support plates, and left and right cover plates. The stator block is fixed to the cylinder body, while the vanes and swing shaft are rigidly connected. When pressurized oil is supplied to both oil ports, the vanes drive the swing shaft to reciprocate.
The swing angle of a single-vane oscillating hydraulic cylinder generally does not exceed 280 degrees. A dual-vane oscillating cylinder has a smaller swing angle, reaching 150 degrees. When the input pressure and flow remain unchanged, the output torque of the oscillating shaft of a dual-vane oscillating hydraulic cylinder is twice that of a single-vane oscillating cylinder with the same parameters, while the oscillation angular velocity is half that of a single-vane oscillating cylinder.
1. Cylinder; 2.Blade shaft; 3.Positioning block; 4. Blade; Dual-blade rotating oscillating hydraulic cylinder
02.Spiral rotating oscillating hydraulic cylinder
Currently, most oscillating hydraulic cylinders are of the helical type, which can be categorized into single-helix and double-helix types, with double-helix types being more commonly used.
A helical oscillating hydraulic cylinder utilizes a helical pair with a large helix angle to achieve rotational motion. The helical rod on the output shaft is fixed to the cylinder body by bearings, providing two degrees of freedom. The helical teeth on the inner surface of the piston mesh with those on the helical rod, and the surface shape of the helical rod on the output shaft matches the outer surface of the piston.
The operating principle is that, under the action of hydraulic pressure within the rotating sleeve, the piston moves both linearly and rotationally along the helical rod, causing the helical rod with the output shaft to rotate simultaneously, thus achieving oscillating motion.
The spiral rotating oscillating hydraulic cylinder has the advantages of compact structure, precise swing angle, high reliability, extremely smooth operation and the ability to achieve extremely low speed.The disadvantages are that it is difficult to process and the cost is high.
03. Characteristics and applications of rotating oscillating hydraulic cylinder
The rotating oscillating hydraulic cylinder has the characteristics of compact structure and large output torque, but it is difficult to seal and is generally only used in low and medium pressure systems for reciprocating swing, indexing or intermittent motion.
Swing rotating oscillating cylinders generally require no maintenance. Every year, open the drain plug and refill with an appropriate amount of lubricant. After extended use, if working medium is detected leaking after opening the drain plug, connect a return line to the drain port to direct the leaked oil back to the tank. Continue operating the cylinder until the output torque no longer meets operational requirements, then replace the seal and perform repairs.
Rotating oscillating hydraulic cylinders have been successfully applied in nearly all applications requiring limited rotational motion and high torque, such as tilting cylinders for steel mill tundishes, swinging cylinders for slewing arms in high-speed wire rod plants, swing reduction cylinders for warships, swing cylinders for road sweepers, and swing cylinders for valve opening. They are also used in the pharmaceutical and food processing industries, where high cleanliness and hygiene are crucial. They are also suitable for extremely harsh working conditions, such as underground and below 2,000 meters above sea level.
1. Vane-Type rotating oscillating Cylinder
Vane-type rotating oscillating cylinders offer low moment of inertia, agile movement, and uniform rotation with minimal pulsation. However, their greatest weaknesses are significant leakage, an inability to operate at very low speeds, and a rapid decrease in speed as the load increases. Furthermore, the large contact area of the dynamic seal results in significant frictional resistance losses and low output efficiency. Consequently, their application is limited, and they are generally used only in applications where mounting locations are restricted, such as fixture rotation, valve opening and closing, and worktable indexing.
2. Screw-Type Oscillating Hydraulic Cylinder
Screw-type oscillating hydraulic cylinders feature a large helix angle and a compact structure, achieving high torque output, high load capacity, shock resistance, zero leakage, and flexible installation.
Spiral rotating oscillating hydraulic cylinders are often used in the following fields: swinging of the working frame of aerial work platform vehicles; swinging and positioning of the drill arm of mining equipment; tire or track steering of agricultural equipment and road equipment; swinging of actuators such as road sweepers and forklifts; flipping of garbage bins on garbage trucks, etc. They are particularly suitable for structural applications with limited installation space to achieve swinging of actuators.
