1、Switches and Sensors For integrated control systems氣動技術雙語電子教案 吳洪明 Chapter 8 SensorWUHAN UNIVERSITY OF TECHNOLOGY LOGISTICS ENG. DEPT. 武漢理工大學 物流工程學院第1頁第1頁ContentsClick the section to advance directly to itMagnetic cylindersReed switch principleSensor principleQM/45/* rangeQM/33,34,134 rangeM/40,41,42

2、 rangeInductive proximity sensorsVacuum electric switchVacuum electronic switchCable capacitanceIntroduction氣動技術雙語電子教案 吳洪明 Chapter 8 Sensor第2頁第2頁IntroductionTypical electro-pneumatic systems consist of:magnetic cylinders and solenoid valves for dynamic powerreed switches and sensors for feedbackelec

3、tronic logic for controlReed switches and solid state magnetic sensors are fitted to cylinders to feedback particular positions of the pistonSolid state proximity sensors can be used to replace limit switches, for detecting the position of mechanisms or other moving partsReed switches and solid stat

4、e sensors are small, fast, easy to fit and adjust. They simplify installation on to the machine application氣動技術雙語電子教案 吳洪明 Chapter 8 Sensor第3頁第3頁Magnetic cylindersMagnetic cylinders have a band of magnetic material inset around the circumference of the pistonThe polarity is in parallel with the axis

5、of the cylinderThe barrel is made of non ferrous materialBy placing reed switches along the outside of the cylinder, signals can be given at the extreme and intermediate positions of strokeClick the illustration to start and stop animation氣動技術雙語電子教案 吳洪明 Chapter 8 Sensor第4頁第4頁Reed switch principleA b

6、asic reed switch consists of a small glass tube containing soft iron contact reeds normally sprung open When a magnetic field is in range the reeds will become magnetic The ends will be of opposite polarity and pull themselves togetherClick the illustration to start and stop animation氣動技術雙語電子教案 吳洪明

7、Chapter 8 Sensor第5頁第5頁Magnetic sensor principleIn the presence of a magnetic field the magnetoresistive sensor has a lower resistance. This causes current to be drawn from the base of the transistor turning it onThe circuit incorporates l.e.d., reverse polarity protection diodes and suppression diod

8、e for an inductive loadsensorNSload+V0V氣動技術雙語電子教案 吳洪明 Chapter 8 Sensor第6頁第6頁Reed switches and sensorSlim cylindrical housingPVC cable in 2 or 5 metre lengthsOptional very flexible polyurethane cableWith or without l.e.d. indicatorRange of four reed switches and one solid state sensor氣動技術雙語電子教案 吳洪明 C

9、hapter 8 Sensor第7頁第7頁Reed switchesBasic reed switchShown connected to a relay or solenoid coil with diode suppression for d.c. application10 to 30V a.c./d.c.Maximum switching power 10 W/VABrownBlue+ V0 VCoilProtection diodefor d.c. onlyQM/45/RAP氣動技術雙語電子教案 吳洪明 Chapter 8 Sensor第8頁第8頁Reed switchesReed

10、switch with l.e.d. indicatorThree wires emulating p.n.p. sensorCurrent sourced on the black wire to the coilResistor protects l.e.d. from over voltageBlueCoilBlack0 VBrown+ V0 VQM/45/LAPProtection diode氣動技術雙語電子教案 吳洪明 Chapter 8 Sensor第9頁第9頁Reed switchesReed switch with l.e.d. indicator and two wires

11、onlyCurrent sourced on the black wire to the coilZener diode provides small voltage drop to turn on l.e.d.10 to 240V a.c./170V d.c. 10 W/VA maximumShown with VDR for suppression a.c. or d.c.BlueCoil0 VVoltage dependant resistor (VDR)Brown+ VQM/45/LAP氣動技術雙語電子教案 吳洪明 Chapter 8 Sensor第10頁第10頁Reed switch

12、esReed switch with l.e.d. indicatorThree wires emulating n.p.n. sensorCurrent sunk on the blue wire from the load to 0VResistor protects l.e.d. from over voltageBrownBlackLoadProtection diode+ VBlue0 V+ VQM/45/LAN氣動技術雙語電子教案 吳洪明 Chapter 8 Sensor第11頁第11頁Solid state switchesSolid state magnetically ope

13、rated p.n.p. outputUsed for applications where vibration levels are unsuitable for reed switchesMagnetoresistive sensor elementSensor on l.e.d. indicator10 to 30 V d.c. 200mA maximumbrownblue black pnp+V 0V 0V coilprotection diodeQM/45/EAP氣動技術雙語電子教案 吳洪明 Chapter 8 Sensor第12頁第12頁Reed switches and sens

14、orsNeat cylindrical housing with fixed or plug-in cableStraight or 90o plug-in connector cablesOptional: very flexible polyurethane cable or high temperature (150oC) silicon cableWith or without l.e.d. indicatorWide range of reed switches and solid state sensors氣動技術雙語電子教案 吳洪明 Chapter 8 Sensor第13頁第13

15、頁Reed switchesPlain reed switchPlain change-over reed switchThree wire reed switch with l.e.d., emulating p.n.p. sensor and plug-in cableThree wire reed switch with l.e.d., emulating n.p.n. sensorTwo wire reed switch with l.e.d.bluebrown +VLoad0V brown +Vblue black0V 0V LoadLoadbrown +Vblue 0V Load+

16、V black brown +VblueLoad0V QM/33QM/33/CQM/34/PQM/34/NQM/34/Sbrown +Vblue 0V Load0V black氣動技術雙語電子教案 吳洪明 Chapter 8 Sensor第14頁第14頁Solid state sensorsOutput p.n.p. fixed cableOutput p.n.p. plug-in cableOutput n.p.n. fixed cableOutput n.p.n. plug-in cablePulse stretcher. Output p.n.p. fixed cable. When o

17、perated and released output will remain on for a further 30 ms approximately. Suitable for part stroke position on fast operating cylinders brown +Vblue 0V blackpnpLoad0V 134pnpbrown +Vblue 0V blackLoad0V 1 brown +VblacknpnLoad+V blue 0V 34npnbrown +VblackLoad+V blue 0V blackLoad0V brown +Vblue 0V Q

18、M/134QM/134/PQM/134/NQM/134/N/PQM/134/X氣動技術雙語電子教案 吳洪明 Chapter 8 Sensor第15頁第15頁Reed switches and sensorsLow profile with dove tail slide for cylinders with integral track in extruded bodyScrew tighteningFixed cable or plug-in connector cables straight or 90oWith or without l.e.d.氣動技術雙語電子教案 吳洪明 Chapte

19、r 8 Sensor第16頁第16頁Reed switches and sensorsLow profile with dove tail slide for cylinders with integral track in extruded bodyScrew tighteningFixed cable or plug-in connector cables straight or 90oWith or without l.e.d.氣動技術雙語電子教案 吳洪明 Chapter 8 Sensor第17頁第17頁Reed switchesTwo wire with l.e.d. 10 to 24

20、0V a.c./170V d.c.With high temperature cable With very flexible polyurethane cableTwo wire with l.e.d. and plug in cable 10 to 60V a.c./74 d.c.Change-over contacts without l.e.d. +VblueLoad0Vbrownbrownblue black0V0VLoadLoad+VM/40M/40/PM/40/C brownblueLoad0V +VTM/40M/40/*/PU氣動技術雙語電子教案 吳洪明 Chapter 8 S

21、ensor第18頁第18頁Solid state magnetic switchesOutput n.p.n. 10 to 30V d.c. 200 mA maximumOutput p.n.p. 10 to 30V d.c. 200 mA maximumOutput p.n.p. with very flexible polyurethane cableOutput p.n.p. with plug-in cable brown +Vblue 0V blackpnpLoad0V brown +VblacknpnLoad+V blue 0V M/41M/42 134pnpbrown +Vblu

22、e 0V blackLoad0V M/42/*/PUM/42/P氣動技術雙語電子教案 吳洪明 Chapter 8 Sensor第19頁第19頁Inductive proximity sensorsSense the presence of metal near the tipUsed as a limit switch for mechanical partsDepending on type:Range 0.8 to 2 mmSwitching frequency 500 to HzWith or without l.e.d.10 to 30 or 6 to 30 V d.c.Normall

23、y closed or normally open p.n.p. outputoutput brownblueblackpnpLoad0V +V brownblueblackpnpLoad0V +VM/P28473M/P70104/1&2M/P70104/3&4M/P70104/5&6M/P70104/7&8M/P70104/9氣動技術雙語電子教案 吳洪明 Chapter 8 Sensor第20頁第20頁Cable capacitanceLong leads above the standard cable length become a long thin capacitor (equivalent circuit)Closing the switch shorts the capacitor, the instant high current overloads and damages the switch contactsFit an inductor (470H) close to the switch. This damps the surge but has a low steady state resistance+ V0 VL+ V0 VLoad+ V0 VEx