What is a Rotary Damper?
A rotary damper is a device designed to decelerate the movement of an object, whether rotary or linear. These dampers can generate substantial resistance or torque, effectively controlling motion in mechanical systems.
How Does a Rotary Damper Work?
A rotary damper slows down movement by rotating around a single axis. It utilizes viscous fluid, typically silicone oil, to create a resistance force against the object's movement.
Different Types of Rotary Dampers and How They Work
Rotary dampers can be classified into two main categories: bidirectional rotary dampers and unidirectional rotary dampers.
Bidirectional Rotary Dampers:
- Barrel Damper
- Disk Damper
Continuous rotation dampers are characterized by having no limited opening angle, allowing them to exert torque endlessly. When combined with rack gears, a continuous rotation damper enables linear motion to be buffered at a constant speed.
Unidirectional Rotary Dampers
Unidirectional rotary dampers are categorized into two types:
1. Limited Angle Damper (Vane Damper)
2. Infinite Angle Damper (With One-Way Clutch)
The primary distinction between these types lies in their force curve: limited-angle dampers have torque that varies at different angles, while infinite-angle dampers maintain consistent torque across all angles.
Limited Angle Damper
Limited angle dampers feature two vanes attached to the rotation shaft, functioning as a valve. As the damper operates, the shaft drives the vanes, creating resistance in one direction only. When the shaft rotates, silicone oil flows gradually through a one-way valve, generating rotational torque. Due to their design, limited-angle dampers have a maximum working angle of 110°.
Infinite Angle Damper
On the other hand, infinite-angle dampers, such as gear or disk dampers with a one-way clutch, allow continuous rotation in one direction while providing resistance. This is achieved by engaging the clutch to control motion in the desired direction and disengaging it for smooth movement in the opposite direction. This design is essential for applications requiring controlled motion over an unlimited range of rotation in one direction.
Tips for Determining Rotary Damper Torque
1. Oil Viscosity:
Thicker oil creates more resistance as it flows through the damper's pathways, resulting in higher torque values. Conversely, thinner oil offers less resistance, leading to lower torque. By adjusting the oil viscosity, you can tailor the damping effects to meet specific application needs.
2. Space Between the Rotor and Outer Casing:
The space between the rotor and the outer casing affects oil flow, which in turn influences the damper's resistance level.
3. Size of the Damper:
A larger oil chamber allows for better fluid flow control, resulting in varied torque capabilities.
4. Material Used for the Damper:
High-torque dampers commonly utilize zinc alloy and steel, while low-torque dampers may be made from plastics like PBT, PA, or POM. Incorporating glass fiber into plastics can enhance their strength.
In addition to these factors, the viscosity of the oil inside the damper affects its torque and varies with temperature—higher temperatures generally result in lower torque, while cooler temperatures yield higher torque. Furthermore, the damper's torque increases with rotation speed.
Engineers designing a damper must consider the application's working temperature and required torque to customize the damper's performance effectively. This ensures the damper provides the appropriate resistance for its specific use, efficiently dissipating kinetic energy as heat.
Rotary Damper Selection Guide
When selecting a rotary damper for a customer, engineers should consider the following key factors:
1. Torque Range or Damping Time:
Match the resistance level to the application needs. For example, a washing machine lid may require a soft-close time of 3-8 seconds.
2. Movement Type:
After determining the optimal torque, select the rotary damper based on the operational movement, such as horizontal or vertical motion.
3. Mounting Dimensions:
TEAO offers over 400 models, ranging from large high-torque dampers to small rotary dampers. Consult directly with an engineer to find the most suitable model.
4. Material and Durability:
TEAO’s rotary dampers are designed for lifecycles of 30,000 to 50,000 cycles, with variations among models. High-torque dampers exceeding 3 N·m use zinc alloy for enhanced durability, while lower torque dampers typically use PBT for its strength. For extended lifecycles, components may incorporate wear-resistant or high-temperature-resistant materials.
5. Special Features:
If customers have specific movement requirements, such as the ability for a lid to stop at any angle and softly close from 15° to 0°, we can customize an optimization plan.
6. Application Requirements:
Consider the specific use and environmental temperature.
These factors assist in selecting a damper that aligns with the functional and performance criteria of the project.
Rotary Damper Applications
Rotary dampers are easy to integrate and are applicable to a wide variety of products.
TEAO offers an extensive range of over 400 models, including rotary dampers, soft-close hinges, friction hinges, friction dampers, gear dampers, disk dampers, and more. This diverse product lineup serves numerous applications across multiple sectors, including automotive, home appliances, and furniture, demonstrating TEAO’s capability to meet a broad spectrum of customer needs.
Applications Include:
- Sanitary: Toilet seats and covers, shower door hinges
- Home Appliances: Refrigerators, washers/dryers, ranges, coffee machines, soda machines
- Automotive: Handles, fuel doors, glass holders, cup holders, EV chargers
- Furniture: Kitchen cabinets, shutters
- Other Uses: Piano covers, vending machine flaps, air filter covers, printers
Common Materials Used in Rotary Dampers
Rotary dampers are typically constructed from robust plastics or metals, with oil viscosity and precise design playing crucial roles in their performance.
Material selection is essential for specific applications, such as toilet seats, where resistance to detergents is vital. In such cases, PBT and zinc alloy are preferred for their durability and strength.
When choosing materials, it’s important to consider the operating environment, cost, and anticipated product lifespan. This ensures the damper functions effectively across a range of applications, from electronics to heavy machinery.
