Inclination sensors Inductive sensors Pressure sensors
System description Selection chart
Inclination sensors
Inductive sensors
Sensors with CAN interface Analogue sensors / switches
Inductive efectormsensors
Pressure sensors
Pressure sensors for mobile hydraulic applications
102 - 107 108 - 109
110 - 111 112 - 113
114 - 117
118 - 119
Visit our website: www.ifm.com The 2-axis inclination sensor with CANopen interface enables levelling and
angular position detection of mobile machines.
Typical applications are for example angle detection of access platforms, levelling of mobile cranes or the set-up of mobile machines working on uneven ground.
This is a group of sensors of which the analogue measured value is evalu-ated, standardised and converted into a CANopen message in the sensor electronics. The structure of the transmitted data is defined via a CANopen profile, like for the I/O modules. Under the profile number 410, inclinometer, all important parameters and the transmission of the user data are defined.
102
Inclination sensors
In automation sensors are the “nerves” of the control system. Sensors are also used in mobile machines and installations. In contrast to the units for industrial automation, however, sensors for mobile applications have to meet considerably higher demands. As they are mounted in exposed posi-tions they have to meet special requirements. The protection rating and the mechanical resistance are important features. The electrical requirements can be compared to those of the controllers, I/O modules and dialogue modules – due to their compact design they are a challenge as regards the circuit development.
Sensors are generally differentiated between units with a built-in CANopen interface and sensors with binary or analogue output stages which are con-nected directly to controllers or I/O modules.
Inclination sensors with a built-in interface
The measuring cells function according to the conductometric principle. The change of conductivity of a liquid is evaluated. Depending on the sensor inclination the electrodes in the liquid are exposed to different degrees of wetness.
This leads to characteristics comparable to that of a potentiometer. Ar-ranging the electrodes crosswise results in the signed values for the two axes. The inclination sensor CR2102 additionally has two analogue outputs.
For this unit the measured values are additionally indicated as current values 4...20 mA.
System description Sensors for
mobile applications Inclination sensors
Principle of incli-nation sensors with a built-in CANopen inter-face.
analogue values
parameter data
interface
measured values
micro-processor
Angle of inclina-tion depending on the sensor axis of CR2101.
Y
transverse inclination
mounting surface
+15% –15% X
longitudinal inclination
+15% –15%
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Visit our website: www.ifm.com Analogue inclination sensors
This sensor type is based on a capacitive acceleration sensor which functions like a capacitor. Depending on the inclination of the sensor a micromass changes the capacitance of the plate capacitor. This generates a sinusoidal output signal. This robust unit is for example suitable for the position detec-tion of loading platforms.
Digital tilt sensors
The mercury-free tilt sensor has one inclination-dependent switch point. In a small switching element there are two electrodes which are shorted by the conductive alcoholic liquid if the sensor is tilted. The output stage amplifies the output signal. The switching signal can then be used for direct triggering of controller inputs or loads.
ifm offers sensors for a wide range of mobile applications.
Inclination sensors
Rotation axis of the inclination sensor.
–45° 0° +45°
Function of the digital tilt sensor.
output stage
Design of a sensor cell.
R
R
C1
C2
U0
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104
Inductive sensors take advantage of the physical effect of a change in the qua-lity factor of a resonant circuit caused by eddy current losses in conductive materials. This is how it works: An LC tuned circuit generates a high-fre-quency electromagnetic field. This field is emitted from the active face of the sensor. If a conductive material passes through this field, eddy currents are formed in accordance with the law of inductance which take energy away from the oscillator. This reduces the oscillation amplitude. This change is converted into a switching signal. The operating principle permits detection of all metals irrespective of whether they are moving or not. Important: The high-frequency field causes no measurable heat in the object nor is there any magnetic interference. So the sensors operate without interaction. The distance to the active face at which an electrically conductive material leads to a signal change in the sensor is called sensing range. The sensing range of an inductive sensor is defined by means of a target made of mild steel. If the sensor is damped by other metals, e.g. aluminium or copper, it changes. By means of correction factors which exist for every kind of metal the user can calculate the sensing range expected.
Inductive sensors
In all automated processes sensors are absolutely necessary to provide the plc with information. They supply the necessary signals on positions, limits or serve as pulse pick-ups for counting tasks or for monitoring rotational speed. In comparison with mechanical switches they offer almost ideal con-ditions: operation without contact and wear as well as high switching fre-quencies and accuracy. In addition, they are not affected by vibration, dust and moisture. Inductive proximity switches detect all metals without contact.
Operating principle of inductive sensors
A special series of inductive sensors are the application sensors which are called “efectorm”– The “m” stands for modular technology. It is based on a new mechanical concept, new assembly methods and an innovative sealing system. It is based on an O ring (made of Viton / EPDM) which is in the front cap and in the plug area. In addition, these areas are sealed using a special cast resin. The reinforced housing provides additional mechanical stability. A high degree of automation is reached in manufacturing. This new produc-tion technology provides high quality sensors. During producproduc-tion all compo-nents and the individual production steps are subjected to a continuous function check. This severe quality testing guarantees permanent reliable operation even under extreme conditions. The common feature of these sensors is an increased sensing range. It permits use where standard units meet their limit.
Modular sensors
Quick set-up:
The set-up LED helps to send the optimum sensing range.
High-frequency electromagnetic field: The inductive sensor detects all metals.
An inductive sensor serves for position monito-ring in a hydraulic system.
Cable drum of a mobile crane: An inductive sensor type M18 moni-tors and signals the end of the cable.
standard setting in practice
adjustment with setting LED
sensing range [%]
80 100
standard sensing range increased Snsafe setting range increased Snunsafe setting range
In practice that means sensing ranges more than 2.4 times greater than using standard sensors.
System description Sensors for
mobile applications Inductive sensors
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Visit our website: www.ifm.com All units have a lasered type label which cannot be lost. The units can be
clearly identified even after many years. No sensor leaves the production without a functional test. Furthermore each unit is tested for full sealing.
This philosophy is specially rewarding for applications in wet areas. A univer-sal connection technology has been developed so that the user can react to his customers and markets quickly and easily. The switches can be used as 3-wire or 2-wire units. One unit provides two connection variants.
The application sensor for mobile applications is also distinguished by this new mechanical concept and the innovative sealing system. Sensor compo-nents like front cap or housing material are adapted to the harsh application conditions. The units are designed to ensure highest shock and vibration resistance. Corrosion-resistant M12 connectors with gold-plated contacts increase the life of the unit. An outstanding advantage for safe detection is the increased sensing range. Due to the high sensing range larger fluctua-tions in the detection area, caused by mechanical tolerances in the vehicles for example, can be better compensated for. This helps to prevent the sen-sor from being damaged. The increased sensing range is of course valid over the complete temperature range of -40...85 °C and the units are insensitive to quick temperature changes.
A voltage range of 10...60 V for mobile sensors ensures that large fluctua-tions of the on-board supply do not impair the function. To meet the in-creasing EMC requirements in the mobile area the efectormunits have an increased EMC resistance of 100 V/m.
Inductive sensors
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106
The most important element of the sensor is the ceramic pressure measuring cell made of aluminium oxide (Al203). It has a disk made of aluminium oxide with a layer of gold resinate (thick layer paste) at the inside. This gold layer forms a measuring electrode and a reference electrode on the aluminium oxide disk. The counterpart is a second disk of aluminium oxide to which another gold layer is applied. This layer forms a second measuring electrode.
Aluminium oxide is used in view of its excellent chemical resistance to high strain and its high resistance to pressure peaks. The two disks are connected by means of a glass frit with the electrode layers being opposite each other.
The distance is approximately 10 μm. After assembly the structure of the ceramic cell is similar to a plate capacitor. The capacitance is invertly propor-tional to the distance between the electrodes. If this distance changes by a small value I because the pressure applied to the cell rises, the capacitance is changed by C.
C+C= 1/ I+I
This shows that the ratio between pressure changes and capacitance (C) is linear if the pressure is proportional to the distance (I). The distance between the electrodes is determined with a constant loading process. The capacitor is loaded by a current source over a certain period of time. The current differ-ence at the beginning and at the end of the loading process is a measure of the deflection of the diaphragm. To compensate for interference and to improve the ratio signal / interference, the signal difference is determined on the basis of the measuring and reference electrodes. This signal is then pro-cessed by a microprocessor.
Pressure sensors
The ifm pressure sensors have been developed for monitoring the system pressure in hydraulic and pneumatic applications. Mobile applications can-not be imagined without pressure sensors either. ifm offers a series of differ-ent types for the differdiffer-ent applications. All units have one thing in common:
They have a one-piece housing and need no moving parts such as pistons or springs. The result: The sensors are robust against mechanical influence and work completely without wear and tear or fatigue.
The sensor has a ceramic measuring cell. The advantage of this material: It is resistant to corrosion and absolutely long-term stable. In the long run this guarantees a continuous accuracy of the measured values. ifm sensors are also resistant to dynamic pressure peaks and have a high overload resis-tance.They are resistant to pressure peaks which typically occur on fast closing valves. In view of the resistance to impact and vibration the electronic sensor components are mounted on a flexible film instead of on a rigid printed circuit board.
Pressure sensors on a valve unit.
The ceramic measuring cell:
In case of overload the diaphragm is supported by the base. This provides security in case of extreme strain.
pressure measuring cell
diaphragm electrodes
ceramics
Operating principle
System description Sensors for
mobile applications Pressure sensors
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Visit our website: www.ifm.com Easy set-up
For sensors with switching output the switch-on point and the switch-off point can be set to any value within the operating range independent of each other before the sensor is mounted. With this feature – called adjust-able hysteresis – one single sensor can for example monitor two pressure values and give a signal if the current value is above or below the preset value at one of the two switching outputs. Damping and delay times can be freely selected by the user. After programming of the switch points the user can lock the sensors electronically against unauthorised access.
PP-series:
Separate display / programming
unit.
In mobile hydraulic applications abruptly switching valves can lead to pres-sure spikes which are much higher than the operating prespres-sure. In particular load monitoring requires the highest reliability. Quick and precise response of the sensor is as indispensable for the protection of the process as clear and easy setting of the sensor. The highly resistant measuring cell can with-stand extremely harsh operating conditions. The electronics allow quick and precise conversion of the sensor signal into switch points.
The new PP75 units of the mobile series are specially adapted to this use.
A special feature of the pressure switches is the e1 type approval by the Kraftfahrt Bundesamt (German Federal Office for Motor Traffic). The sensor is designed to have a high EMC and shock resistance.
The pressure sensors often have to be mounted at places which are difficult to access in the vehicle or machine. Programming and reading of the values on site are difficult. The solution: Sensors of the PP series with EPS interface.
Pressure sensor and control monitor are located in the sensor housing on site. Programming is performed using the programming unit (PP2000) which is connected to the sensor by a cable. The sensors can be set by Teach button directly at the measuring point with medium pressure being applied.
The current medium pressure applied is stored as measured switch point.
As feedback for the successfully terminated operation the pressure switch gives an output signal which is confirmed by the LED lighting on the Teach button. This easy type of setting can also be activated or made by a remote button in a central operating panel or even automated by a plc. In addition, PP2000 can also be used as remote display. An electronic lock protects against unauthorised access to the configuration.
Pressure switches for mobile hydraulic applications
Pressure sensors
Selection chart Sensors for
mobile applications
Inclination sensors Inductive sensors Pressure sensors
108
+/- 15˚
Inclinometer
Inclination sensor
110
– – • M12 plug
+/- 45˚ – • • M12 plug 110
+/- 90˚ – • – cable 112
+/- 90˚ – • – cable 112
Inclination sensor, pigtail M12
Standard series
4...22 mm
(UB= 10...36 V) • – – cable or connector 116
Standard series
4 mm
(UB= 10...36 V) • – – cable 116
High-end series
4...22 mm
(UB= 10...60 V) • – – cable or connector 114
Tilt switch
2,5...5˚ • – – cable 112
Inclination sensors
Inductive sensors
Type Operating range Output signal Connection Page
analogue
digital CAN bus
+/- 20˚ – • – pigtail with M12 plug 112
+/- 90˚ – • – pigtail with M12 plug 112
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Inclination sensors Inductive sensors Pressure sensors
Type Operating range Output signal Connection Page
analogue
digital CAN bus
0...400 bar type PP75..
118
• – – M12 connector
Pressure sensors
Pressure transmitter
0...600 bar – 1 x
4...20 mA – M12 connector
type PA30..
118
0...600 bar – 1 x
0...10 V – M12 connector
type PA90..
118
Inclinometers
2-axis inclination sensor
The automation of vehicles and mobile machines can no longer be imagined without controller electronics and sensors. Often the horizontal alignment of machines or machine parts is an important requirement for reliable operation. Typical examples are mobile cranes or access platforms.
The inclinometer detects precisely the deviations of the two measurement axes (X and Y direction). As the sen-sor must often be mounted at difficult positions in the vehicle, special attention has been given to the mecha-nical and electrical properties of the sensor during deve-lopment. The high accuracy is achieved with measuring cells which operate to the conductometric principle. The change in conductivity of a liquid is determined. Depen-ding on the sensor inclination the electrodes are sur-rounded by a different level of liquid. This results in a behaviour comparable to that of a potentiometer. Due to a suitable arrangement of the electrodes the signed values for the two axes are obtained.