A hydraulic flow divider/synchronizing motor, as the name suggests, has two core functions:
Flow Dividing: It precisely divides one input oil flow into two or more equal output flows, driving multiple actuators (cylinders or motors) to move synchronously.
Flow Combining: During reverse operation, it combines multiple input oil flows into a single output.
Its essence lies in being a rigidly linked set of gear motors. Its synchronization is not achieved through electronic sensors or complex valve control but is ensured by purely mechanical,compulsory gear meshing. Hence, it is also known as a gear-type flow divider.
1. Working Principle
(1) Basic Structure
Imagine a closed housing containing two (or more) identical gear pairs (gears and shafts). These are rigidly connected via a shared linkage gear or direct meshing, ensuring all shafts rotate at the exact same speed. Each gear pair constitutes an independent metering motor unit, with its own inlet/outlet.
(2) Diverting Process (Synchronous Extension)
① Pressure Oil Input:
Pressure oil (flow rate Q) supplied by the hydraulic pump enters the diverting motor housing through the common inlet (P port).
② Drive Gear Rotation:
Pressure oil fills the meshing space of the gears, driving all gear pairs to rotate. Since all gear shafts are rigidly connected, they must rotate together at the exact same speed (RPM).
③ Equal Flow Diversion:
Each gear pair is a precise metering unit. The volume of oil discharged from its outlet is constant for each gear rotation (determined by its gear parameters). Because all gear pairs are identical and rotate at absolutely synchronized speeds, the flow rates (Q1, Q2) discharged from each outlet are necessarily equal.
④ Drive actuators:
These two equal flow streams are respectively delivered to two hydraulic cylinders (or motors), pushing them to extend or rotate at the same speed, thereby achieving synchronous movement.
(3) Flow Combination Process (Synchronous Retraction)
When the actuator needs to retract, the process is exactly the opposite:
① Oil Input:
Under load, the two cylinders retract, and the discharged oil (flow rates Q1′ and Q2′ respectively) enters the two outlets of the flow divider motor (which then act as inlets).
② Drive Gear Rotation:
The oil drives the gear pair to rotate. Due to the rigid connection, all gears maintain synchronous speed.
③ Equal Flow Combination:
The oil flow rate drawn into each gear pair is forced to be consistent. The two flows converge and flow out from the common outlet (P port).
④ Return to Tank:
The merged oil flows back to the tank or hydraulic system.Key Point: Regardless of whether in flow division or flow combination mode, the speed of all output shafts/gears is forced to be equal, thus ensuring the average distribution or convergence of flow.
2. Characteristics and Advantages/Disadvantages Analysis
(1) Advantages:
① True speed synchronization:
The rigid mechanical connection ensures extremely high synchronization accuracy (typically ±1% ~ ±3%), unaffected by changes in load pressure. Even if the loads on the two cylinders are different (F1 ≠ F2), their movement speeds remain consistent.
② High reliability:
Purely mechanical structure, requiring no electronic sensors, controllers, or complex hydraulic valves; strong resistance to contamination, suitable for harsh environments.
③ Compact structure:
Small size, easy installation.
④ Cost-effective:
For multi-branch synchronization systems, it is generally less expensive than solutions using multiple servo valves or proportional valves.
(2) Disadvantages and Precautions:
① Synchronization accuracy will decrease:
Although speed is synchronized, position synchronization accuracy will accumulate errors over time. Because internal leakage is unavoidable, even small leakage differences will cause deviations in the final stopping position of the actuator. Therefore, mechanical limit switches or hydraulic locks are usually required to ensure final position synchronization.
② Limited load tolerance:
Excessive load differences will manifest as pressure differences. Branches with lower loads have lower pressure, while branches with higher loads have higher pressure. However, the total operating pressure of the system must meet the demand of the branch with the highest load. In extreme cases, branches with lower loads may need to overflow due to excessive pressure.
③ Requirements for oil cleanliness:
Precision gear pairs are susceptible to contamination. Poor oil cleanliness will lead to accelerated wear, increased internal leakage, and decreased synchronization accuracy.
④ Pressure loss:
Oil flowing through the gear pair will cause a certain pressure drop.