The arc spring (also known as - bow spring,curved spring, circular spring or "banana" spring) is a special form of coil spring which was originally developed for use in the dual-mass flywheel of internal combustion engine drive trains. The term "arc spring" is used to describe pre-curved or arc-shaped helical compression springs. They have an arc-shaped coil axis. [1]
Like other technical springs, arc springs are based on the fundamental principle of storing mechanical work in the form of potential energy and the ability to release this energy again. The force is applied through the ends of the spring. A torque can be transmitted around an axis via the force directed along this helical axis and the lever arm to the system center point . The wire of the arc spring is mainly subjected to torsional stress. [3] [4]
An arc spring requires suitable support to transmit torque. The support is usually provided from the outside in the form of an arcuate channel (sliding shell) or radially shaped support plates. This prevents buckling of the arc spring. Another result of this support is a hysteresis between the loading and unloading curves in the characteristic curve. This results from the friction of the spring on the radial support and is an intended effect to achieve damping in the system. [5]
As with compression springs, spring systems can also be used for arc springs. The main designs are series and parallel connection. With these, single-stage or multi-stage spring characteristics can be achieved. In order to make optimum use of the available space, systems consisting of inner and outer arc springs are often used.
In addition, the spring characteristic can be influenced by other parameters such as the cross-sectional geometry of the wire, the coil diameter or the number of coils. CAD configurators, which generate a CAD model after entering certain parameters, can contribute to optimal design. [6]
The arc spring is suitable for static and quasi-static as well as dynamic applications. Examples include:
In principle, the spring steels used for ordinary coil springs can also be used for arc springs. These are:
| Term | Definition |
|---|---|
| wire diameter [mm] | |
| mean coil diameter [mm] | |
| e | outer coil diameter [mm] |
| spring active radius [°] | |
| 0 | free angle [°] |
| c | solid angle [°]; angle of the arc-spring at which the coils have contact |
| active coils | |
| t | total coils |
| spring rate [Nmm/°] |
The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-called compression-ignition engine. This contrasts with engines using spark plug-ignition of the air-fuel mixture, such as a petrol engine or a gas engine.
A gyroscope is a device used for measuring or maintaining orientation and angular velocity. It is a spinning wheel or disc in which the axis of rotation is free to assume any orientation by itself. When rotating, the orientation of this axis is unaffected by tilting or rotation of the mounting, according to the conservation of angular momentum.
A flywheel is a mechanical device which uses the conservation of angular momentum to store rotational energy; a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed. In particular, assuming the flywheel's moment of inertia is constant then the stored (rotational) energy is directly associated with the square of its rotational speed.
An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire wound into a coil. A current through the wire creates a magnetic field which is concentrated in the hole, denoting the center of the coil. The magnetic field disappears when the current is turned off. The wire turns are often wound around a magnetic core made from a ferromagnetic or ferrimagnetic material such as iron; the magnetic core concentrates the magnetic flux and makes a more powerful magnet.
A stepper motor, also known as step motor or stepping motor, is a brushless DC electric motor that divides a full rotation into a number of equal steps. The motor's position can be commanded to move and hold at one of these steps without any position sensor for feedback, as long as the motor is correctly sized to the application in respect to torque and speed.
A solenoid is a type of electromagnet formed by a helical coil of wire whose length is substantially greater than its diameter, which generates a controlled magnetic field. The coil can produce a uniform magnetic field in a volume of space when an electric current is passed through it. The term solenoid was coined in 1823 by André-Marie Ampère.
In mathematics and physics, the right-hand rule is a common mnemonic for understanding orientation of axes in three-dimensional space.
A coil spring is a mechanical device which is typically used to store energy and subsequently release it, to absorb shock, or to maintain a force between contacting surfaces. They are made of an elastic material formed into the shape of a helix which returns to its natural length when unloaded.
A torsion spring is a spring that works by twisting its end along its axis; that is, a flexible elastic object that stores mechanical energy when it is twisted. When it is twisted, it exerts a torque in the opposite direction, proportional to the amount (angle) it is twisted. There are various types:
A DC motor is any of a class of rotary electrical motors that converts direct current (DC) electrical energy into mechanical energy. The most common types rely on the forces produced by magnetic fields. Nearly all types of DC motors have some internal mechanism, either electromechanical or electronic, to periodically change the direction of current in part of the motor.
Rolling is a type of motion that combines rotation and translation of that object with respect to a surface, such that, if ideal conditions exist, the two are in contact with each other without sliding.
A balance spring, or hairspring, is a spring attached to the balance wheel in mechanical timepieces. It causes the balance wheel to oscillate with a resonant frequency when the timepiece is running, which controls the speed at which the wheels of the timepiece turn, thus the rate of movement of the hands. A regulator lever is often fitted, which can be used to alter the free length of the spring and thereby adjust the rate of the timepiece.
Rotation around a fixed axis is a special case of rotational motion. The fixed-axis hypothesis excludes the possibility of an axis changing its orientation and cannot describe such phenomena as wobbling or precession. According to Euler's rotation theorem, simultaneous rotation along a number of stationary axes at the same time is impossible; if two rotations are forced at the same time, a new axis of rotation will appear.
The rotor is a moving component of an electromagnetic system in the electric motor, electric generator, or alternator. Its rotation is due to the interaction between the windings and magnetic fields which produces a torque around the rotor's axis.
A brushed DC electric motor is an internally commutated electric motor designed to be run from a direct current power source and utilizing an electric brush for contact.
Flywheel energy storage (FES) works by accelerating a rotor (flywheel) to a very high speed and maintaining the energy in the system as rotational energy. When energy is extracted from the system, the flywheel's rotational speed is reduced as a consequence of the principle of conservation of energy; adding energy to the system correspondingly results in an increase in the speed of the flywheel.
Attitude control is the process of controlling the orientation of an aerospace vehicle with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc.
Magnetic levitation (maglev) or magnetic suspension is a method by which an object is suspended with no support other than magnetic fields. Magnetic force is used to counteract the effects of the gravitational force and any other forces.
Electromagnetic clutches and brakes operate electrically, but transmit torque mechanically. This is why they used to be referred to as electro-mechanical clutches or brakes. Over the years, EM became known as electromagnetic versus electro mechanical, referring more about their actuation method versus physical operation. Since the clutches started becoming popular over 60 years ago, the variety of applications and brake and clutch designs has increased dramatically, but the basic operation remains the same.
A dual-mass flywheel is a rotating mechanical device that is used to provide continuous energy in systems where the energy source is not continuous, the same way as a conventional flywheel acts, but damping any violent variation of torque or revolutions that could cause an unwanted vibration. The vibration reduction is achieved by accumulating stored energy in the two flywheel half masses over a period of time but damped by arc springs, doing that at a rate that is compatible with the energy source, and then releasing that energy at a much higher rate over a relatively short time. A compact dual-mass flywheel often includes the whole clutch, including the pressure plate and the friction disc.
{{cite web}}: CS1 maint: url-status (link)