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Lighter Spring Pressure Brakes For Mobile Devices

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Lighter Spring Pressure Brakes For Mobile Devices
Lighter Spring Pressure Brakes For Mobile Devices

Video: Lighter Spring Pressure Brakes For Mobile Devices

Отличия серверных жестких дисков от десктопных
Video: Hydraulic Brakes 2023, February
Anonim

Anyone who has ever operated a hand-held circular saw knows that the saw decelerates quickly from the movement and must stop safely when it is at a standstill. For this reason, electromagnetic spring-applied brakes are used as safety brakes. It is also pleasant if the circular saw is also small and light.

They are usually installed on the B bearing side of an electric motor. In the de-energized state, springs press against the armature plate of the brake. The friction linings of the rotor, which is connected to the motor shaft via a toothing, are clamped between this armature disk and the mounting surface of the brake on the back of the motor. When the brake coil is energized, a magnetic field builds up, which attracts the armature disk and thus releases the rotor with the friction linings. The brake releases. The brake is therefore closed in the de-energized state. This principle makes spring-applied brakes fail-safe, even in the event of a power failure or damage to the brake.

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New principle offers better performance

These brakes have been in use for decades and follow a similar design principle (see box text). Kendrion has developed a new, patented concept in which the brake is housed in a plastic housing. This design is intended to provide the user with a holding brake with improved electromagnetic performance. According to the manufacturer, the new spring-applied brakes are up to 10% smaller in diameter and length than comparable products on the market and up to 60% lighter than them.

The magnet housing is constructed in such a way that only the cross sections required for the magnetic flux consist of magnetically conductive material. The rest of the contour consists of a plastic, which should enable an optimal magnetic design. Due to the smaller iron cross-sections, a comparatively lower coil power is required to achieve the required magnetic flux. No wastage has to be compensated. Another advantage of this design is short switching times.

The construction of the one-piece rotor should also contribute to optimization. It consists of a pressable friction lining mass without a carrier body with a polygonal inner profile. It is connected to the motor shaft via a sintered hub with a corresponding outer profile (polygon). The one-piece construction of the rotor has a smaller mass moment of inertia, which ensures quick start-up behavior and offers advantages at high motor speeds.

be compensated. Another advantage of this design is short switching times.

Additional information on conventional technology and its limits

Spring brakes are available in many designs. They have been following a comparable design principle for decades: The parts relevant to the magnetic circuit are made of a metallic turned, cast, deep-drawn or cold-extruded part. There are also bushings, flanges, disks and screws with which the massive brakes are attached to the other drive components. The brakes are considered robust and offer good thermal conductivity so that they can be easily installed directly in the motor housing.

However, there are also disadvantages: The brakes are too heavy, too big or too expensive for some applications. Smaller electric motors in mobile applications such as battery-operated tools require light, small brakes that offer a good price / performance ratio in series applications. Light brakes are also in demand in other applications, from stair lifts to lightweight robots, where they can replace mechanical parking brakes.

Modular design simplifies assembly

The brakes are modular and are delivered pre-assembled. The magnet housing and the brake flange to which the brake is attached are overmolded with a plastic. The brake should be easy to install thanks to the two housing halves. There is no need to press sleeves and flanges into the magnet housing. The plastic brakes are available with braking torques of 0.5 Nm to 2 Nm and are therefore suitable for applications that require small and light brakes. Due to the good price / performance ratio, they also offer themselves as an electrically switchable replacement for mechanical parking brakes. (kj)

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