Good to know
Rotary solenoids - long service life
Our rotary solenoids have a rotation angle of up to 95° (depending on size) and a starting torque of up to 13Nm. The robust design allows the use for applications with a high life expectancy of up to 50 million cycles. The design of these rotary solenoids is based on a 3 ball construction. By mechanically incorporating an inclined plane, a linear motion is converted into a rotary motion. Three uniform spiral grooves (called "ball races") are stamped into the housing and armature. The ball races convert the linear motion into a rotary motion and at the same time form the bearing system for the rotary motion. For optimal installation, the rotary solenoids are available with many options e.g. shaft end on both sides, integrated spring return, dust cover or armature plates with thread.
1. Design and Features
The rotary solenoid's design starts from a standard flat face push-pull solenoid. The rotary solenoid then incorporates the mechanical design principle of an inclined plane to convert linear motion to rotary motion. There are three uniform inclined planes (spiral grooves) that are stamped into both the case and the armature, called "ball races. The "ball races" provide both a means of converting linear motion to rotary motion and a secondary bearing system to support this rotary motion. The ball races are specially designed and provide a constant torque output over the complete angle of rotation at 25% duty cycle. The rotary solenoid uses an enclosed coil and therefore provides maximum magnetic efficiency. The magnetic circuit is very short, so high efficiencies in terms of torque output can be obtained, and energization/response times are very quick.
2. Starting Torque
The starting torque shown in the catalog is the gross value output at 20°C. With the addition of the return spring, the solenoid's net output is the gross starting torque minus the return spring torque.
3. Rotation Angle Direction of Rotation
A) Use of an External Stopper
The angle and direction of rotation are predetermined (and fixed) by the manufacturing process of the three ball races that are in the case and armature. The degree of rotation can be reduced (example: a 35 deg RH rotation solenoid reduced to 30 deg RH rotation) by the use of an external stopper. However, to assure that the solenoid operates properly, it is imperative that the solenoid armature always be allowed to return to 0 deg. or unenergized position.
B) Direction of Rotation
The normally accepted convention to describe the rotation of the rotary solenoid is that the direction of rotation is viewed from the armature plate (top) of the solenoid. Clockwise rotation is right-hand (RH) rotation, and counterclockwise rotation is left-hand (LH) rotation.
C) Rotation Angle Available
The rotation angles are available as follows: 25°, 35°, 45°, 67.5° and 95°
4. Axial Travel
In this design of the rotary solenoid the rotary motion is created by converting linear motion into rotary motion. The use of the inclined plane (ball races) also generates a small axial stroke (about 0.7 to 2.6mm depending upon the amount of rotation and the size of the solenoid).
5. Standard Available Accessories
The standard rotary solenoid is available with different accessories to meet your application requirements.
- Shaft extension on the armature plate
- Shaft extension on the base side
- Dust cover over armature plate
- Return spring provided
- Dust cover over armature plate
6. Operational Considerations
The coil data of rotary solenoids shows the values at ambient temperature 20°C and with a standard heat sink. When a solenoid is used at the ratings mentioned in the coil data, it is designed so that the coil temperature rises and reaches equilibrium at approximately 85°C. In applications where the ambient temperature is higher than 20°C or the heat sink is smaller than indicated in the catalog, possible thermal damage can occur. Temperature rise tests should be performed by the customer to assure that the coil does not reach 120°C. Coils can be constructed to operate at temperatures higher than 120°C without thermal damage. Please consult the factory for details.
B) Shaft Modifications
It is not recommended that the customer modify the shaft, as the shafts are fabricated before assembly Any special configurations can be supplied. Please consult the factory for details.
C) How to Use The "T" (tapped armature plate) Feature
As noted above, the rotary solenoid does have axial movement in the armature plate position during energization and de-energization. When directly attaching a mechanism to the armature plate, the load must allow for free movement in the axial direction. Also, the attaching screws cannot be longer than the thickness of the armature plate or interference in the rotary motion will occur.
7. General Characteristics
Insulation class: Class E (120°C), Lead wire class A (105o)
Dielectric strength: AC 1000V 50/60 Hz 1 min. (at normal temperature and normal humidity)
Insulation resistance: More than 100 Megohm at DC 500 V megger (At normal temperature and normal humidity)
Expected life: Standard life 2 million cycles, Extended life 10 million cycles, Long life 50 million cycles (Solenoid cycle life is very dependent upon side load, frequency of use, and environmental conditions. Cycle life tests should be performed by the customer.)
8. How to Select a Rotary Solenoid
Before selecting a rotary solenoid, the following information must be determined.
The actual torque required in the application should be increased using a safety factor multiplier of 1.5 to arrive at the torque value that should be used in your specification.
B) Duty Cycle
Use the aforementioned formula to calculate duty cycle. Also note the maximum on time.
C) Rotation Angle
Rotation angle is determined by application requirements.
D) Rotation Direction
Rotation direction is determined by application requirements (note direction of armature plate).
E) Operating Voltage
Operating DC voltage is determined by the application and voltage available. After determining these specifications, one can find the correct size solenoid for the application, using the torque characteristics tables. The coil data is also shown for different sizes of magnet wire. If the exact operating voltage is not in the coil data table, use the nearest voltage shown in the table. NOTE: When the operating voltage falls between 2 coil sizes, always us the higher AWG numbered coil so as to prevent potential thermal damage.
9. Ordering Information
When ordering a rotary solenoid, the correct part number needs to be determined from the following combination of characteristic (1-5):
(1) M-Metric Thread, F-SAE Thread
(2) Solenoid Size (example - 490)
(3) Coil Wire Size (AWG no.)
(4) Angle of rotation, direction of rotation and accessories
(5) Life time: R - Standard Life Bearing, RE - Extended Life Bearing, RL - Long Life Bearing
10. Accessories Definition Table
When ordering a rotary solenoid, the correct number for the angle of rotation, direction and accessories needs to be determined from the table.
|Rotary angle 25°, starting torque
|Rotary angle 35°, starting torque
|Rotary angle 45°, starting torque
|Rotary angle 67.5°, starting torque
|Rotary angle 95°, starting torque