9 - AHP Merkle GmbH
9 - AHP Merkle GmbH 9 - AHP Merkle GmbH
! 3.2 Magnetic field sensors 80 Magnetic fi eld sensors have a current fl owing through them, and can detect magnetic fi elds of a certain strength. If a magnet (magnetic fi eld) is brought to the sensor, it delivers an output voltage. For this purpose, a magnet is integrated into the piston; this magnet can then be detected from outside. This allows unproblematic fl exible, individual adjustment of the sensing points. However, when magnetic fi eld sensors are used the cylinder housing has to be non-magnetic so as not to infl uence the magnetic fi eld being detected. The operational limits of these simple position sensors are at 105 °C (221 °F). AHP Merkle also offers a solution that goes up to 130 °C (266 °F); this is implemented through the use of switches with displaced electronics. Here the evaluation electronics are not located directly on the sensor element, but rather at a distance of up to 0.5 m (1.64 ft) via a cable connection. Due to their measurement principle, magnetic fi eld sensors are especially vulnerable to electromagnetic interference pulses, such as those that may occur in industrial environments. Therefore it should be checked ahead of time whether this type of sensor is suitable for the specifi c application. As a basic rule, ferromagnetic components have a negative infl uence on the functionality of magnetic fi eld sensors, and should therefore not be placed closer than 30 mm (11.8 inches) from the sensor.
3.3 Mechanical switches The greatest advantages of mechanical position switches are their robust design and their high switching current carrying capacity. They are generally switched via a cam or a switching lug, which actuates the sensor plunger, which then closes the electric circuit. Thanks to their high operational temperature limits of about 80 °C (176 °F) (in special cases even up to 180 °C (356 °F), they are outstandingly suitable for particularly diffi cult environment conditions, for example foundries. For high operating frequencies it is necessary to check whether the associated mechanical wear will have any effects on functionality over the entire period of operation. 3.4 Linear position transducers Switches and sensor systems en Linear position transducers are superbly suited for closed-loop control processes. They are available in non-contact (magnetostrictive and inductive) and contact-type (potentiometer) options. The linear position transducers most frequently used in hydraulic cylinders are based on the magnetostrictive principle. Magnetostriction is the deformation of ferromagnetic materials due to the application of a magnetic fi eld. This causes the body to undergo an elastic change in length at a constant volume. A signifi cant advantage is that they can be connected directly to typical bus systems, such as CAN bus or Profi bus. Their maximum precision of 1 µm (39.37×10−6 inches) is superbly suited for very precise control of hydraulic cylinders. Their maximum possible measurement length is 4,000 mm (1,574.8 inches). 81
- Page 34 and 35: 2.7 Zentrierbund 2.8 Nut ! 30 Wird
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- Page 55 and 56: ahp informiert. 1 Basic information
- Page 57: 2.7 Centering collar . . . . . . .
- Page 60 and 61: 56 Circular block cylinder (RZ) Cir
- Page 62 and 63: 1.3 General calculations ! 58 Conve
- Page 64 and 65: 60 Buckling strength Proper dimensi
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- Page 68 and 69: 1.11 Effect of external forces ! 64
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- Page 72 and 73: 68 Leakage oil As a special design
- Page 74 and 75: 2 Cylinder parameters 2.1 Component
- Page 76 and 77: 2.4 Hydraulic cylinders with specia
- Page 78 and 79: 74 Multiposition cylinders Multipos
- Page 80 and 81: 2.7 Centering collar 76 If the cyli
- Page 82 and 83: Tip 2.10 Corrosion-resistant design
- Page 86 and 87: 4 Operating and maintenance instruc
- Page 88 and 89: ! 84 Installing the rod seal If the
- Page 90 and 91: ! Tip ! 86 Installing the guide rin
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- Page 94 and 95: 90 Adjustable inductive proximity s
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!<br />
3.2 Magnetic field sensors<br />
80<br />
Magnetic fi eld sensors have a current fl owing through them, and can detect magnetic fi elds of a certain strength.<br />
If a magnet (magnetic fi eld) is brought to the sensor, it delivers an output voltage. For this purpose, a magnet<br />
is integrated into the piston; this magnet can then be detected from outside. This allows unproblematic fl exible,<br />
individual adjustment of the sensing points. However, when magnetic fi eld sensors are used the cylinder housing<br />
has to be non-magnetic so as not to infl uence the magnetic fi eld being detected.<br />
The operational limits of these simple position sensors are at 105 °C (221 °F). <strong>AHP</strong> <strong>Merkle</strong> also offers a solution<br />
that goes up to 130 °C (266 °F); this is implemented through the use of switches with displaced electronics.<br />
Here the evaluation electronics are not located directly on the sensor element, but rather at a distance of up<br />
to 0.5 m (1.64 ft) via a cable connection.<br />
Due to their measurement principle, magnetic fi eld sensors are especially vulnerable to electromagnetic interference pulses,<br />
such as those that may occur in industrial environments. Therefore it should be checked ahead of time whether this type of<br />
sensor is suitable for the specifi c application.<br />
As a basic rule, ferromagnetic components have a negative infl uence on the functionality of magnetic fi eld sensors, and<br />
should therefore not be placed closer than 30 mm (11.8 inches) from the sensor.
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