Family of R744 control valves and suggestions for efficient testing

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1 Family of R744 control valves and suggestions for efficient testing Norbert Stulgies, Axel Müller, Horst Kappler, Timo Greeb, Wilhelm Tegethoff, Sven Försterling, Jürgen Köhler 1

2 Contents 1. Motivation 2. Fundamentals 3. Prototype valves 4. Test rigs 6. Conclusion 2

3 Contents 1. Motivation 2. Fundamentals 3. Prototype valves 4. Test rigs 6. Conclusion 3

4 1. Motivation Possible field of application proportional expansion valve source: Behr 4 proportional compressor control valve

5 1. Motivation Usage of control valves designed for R744-compressors reduce fuel consumption Design and development of proportional valves experimental analysis with CO 2 and air as reference medium Goal: Production with end of line inspection 5

6 Contents 1. Motivation 2. Fundamentals 3. Prototype valves 4. Test rigs 6. Conclusion 6

7 2. Fundamentals Proportional solenoid coil armature pressure resistant tube pole yoke disc housing cross section of proportional solenoid magnetic hysteresis curve 7

8 Contents 1. Motivation 2. Fundamentals 3. Prototype valves 4. Test rigs 6. Conclusion 8

9 3. Prototype valves Prototype valve for compressor control Voltage 12 V DC PWM 400 Hz Current controlled 2 valve types with one solenoid - normally closed - normally opened Fluid outlet Fluid inlet normally closed normally opened solenoid 9

10 3. Prototype valves Prototype valve for compressor control Voltage 12 V DC PWM 400 Hz Current controlled sealing element direction of magnetic force normally closed normally opened solenoid 10

11 Contents 1. Motivation 2. Fundamentals 3. Prototype valves 4. Test rigs 6. Conclusion 11

12 4. Test rigs R744-refrigerant cycle gas cooler CO -cycle 2 T P ṁ bypass T P expansionvalve P test-valve T compressor T P evaporator P P dp sensor controller T 12

13 4. Test rigs R744-refrigerant cycle Principle of mass flow rate acquisition: Pressure drop over orifice fast response on variation of pressure difference (0-100%: 6ms) gas cooler T P ṁ CO -cycle 2 bypass T P Inlet conditions: p = 47 bar (-1.5 bar) ϑ = 50 C (±1K) Oil ratio < 4% expansionvalve T P evaporator P test-valve T P P dp sensor controller compressor T 13

14 4. Test rigs Air test rig Inlet conditions: p = 6 bar ϑ = 26.5 C (±1.5K) compressed air pressure control valve flow meter pressure sensor p test valve ambient pressure 14

15 Contents 1. Motivation 2. Fundamentals 3. Prototype valves 4. Test rigs 6. Conclusion 15

16 5.1 Step response on mass flow rate 5.2 Valve characteristic 5.3 Influence of mounting orientation 5.4 Hysteresis 16

17 5.1 Step response on mass flow rate Goal: Measurement of valve response time due to change of control current Identifying differences between increasing and decreasing control current 17

18 5.1 Step response on mass flow rate Valve type: normally opened 1.0 current [-] mass flow rate [-] time [s] time [s] 18

19 5.1 Step response on mass flow rate Valve type: normally opened 1.0 a) b) current [-] mass flow rate [-] time [s] time [s] 19

20 5.1 Step response on mass flow rate Valve type: normally opened a) steady state after approx. 0.1 s b) steady state after approx. 0.4 s ms 10 ms mass flow rate [-], current rent [-] current mass flow rate mass flow rate [-], current rent [-] current mass flow rate time [s] time [s] 20

21 5.2 Valve characteristic (current ramp) Increase of current steady state decrease of current Current ramp: 50 ma/s normally closed normally opened 21

22 5.2 Valve characteristic (current ramp) 22

23 5.2 Valve characteristic (current ramp) 23

24 5.2 Valve characteristic (current ramp) 24

25 5.2 Valve characteristic (current ramp) 25

26 5.3 Influence of mounting orientation (current ramp) g 26

27 5.3 Influence of mounting orientation (current ramp) g 27

28 5.3 Influence of mounting orientation (current ramp) g 28

29 5.4 Hysteresis (current ramp) 29

30 5.4 Hysteresis (current ramp) 30

31 5.4 Hysteresis (current ramp) 31

32 5.4 Hysteresis (current ramp) 32

33 Contents 1. Motivation 2. Fundamentals 3. Prototype valves 4. Test rigs 6. Conclusion 33

34 6. Conclusion Short response time of prototype valves R744-valves can be characterised by air as reference medium Influence of mounting orientation is negligible Hysteresis of R744 and air is similar 34

35 Thanks for your attention! 35