Cliquez pour modifier les styles du texte du masque Deuxième niveau Troisième niveau

Transcription

1 Quatrième «Pneumatic-Combustion niveau Hybrid Engine: Cinquième A study of the niveau effect of the valve-train sophistication on pneumatic modes.» P. Brejaud, A. Charlet, Y. Chamaillard, A. Ivanco, P. Higelin

2 Summary 2 1. Introduction. 2. Cliquez Idealized pour cycles. modifier les styles du 3. Kinematic Model of the charging valve. 4. Quasi dimensional Engine model. 5. Simulations Results. 6. Conclusion.

3 3 Deuxième 1 - INTRODUCTION niveau

4 1 - Introduction 4 Air tank Intake Quatrième New thermodynamic cycles niveau : PNEUMATIC PUMP MODE (*) PNEUMATIC MOTOR MODE (*) UNDER-CHARGED CONVENTIONAL MODE SUPER-CHARGED CONVENTIONAL MODE Exhaust

5 Pneumatic Hybrid Concept 5

6 Valve train technologies 6 Intake Air tank 2-Stroke PUMP and MOTOR Exhaust 4-Stroke PUMP and MOTOR 4-Stroke PUMP with Exhaust Off 4 Stroke MOTOR with Inlet Off

7 7 Deuxième 2 - IDEALIZED niveau CYCLES

8 2-STROKE PNEUMATIC MOTOR 8

9 4-STROKE PNEUMATIC MOTOR 9

10 4-STROKE PNEUMATIC MOTOR INLET OFF 10

11 2-STROKE PUMP CYCLE 11

12 4-STROKE PUMP CYCLE 12

13 4-STROKE PUMP CYCLE EXHAUST OFF 13 1/9/2009

14 All idealized cycles presented suppose an instantaneous opening and closure of the valves, thus an Infinite acceleration 14

15 KINEMATIC MODEL OF THE CHARGING VALVE

16 Kinematic Model Of The Charging Valve γ = γ θ 2.ω 16 +γ max -γ max +V max -V max l max Δθe Δθe Ө (rad) Cliquez Δθe pour Δθe modifier les styles du 2 Δθe lmax = γ max. texte du Δθmasque ω lmax lmax Δθ 4. ω Δθ < 4. ω γ max γ max Ө (rad) Δθ c 0 Δθ c = 0 the valve reaches the desired lift l max Δθc Δθ Ө (rad) l Δθe = ω γ max max v max Δθe = γ max. ω the valve does NOT reach the desired lift l max l effective Δθe = = γ max 4 Δθ. 4. ω 2

17 Kinematic Model Of The Charging Valve Desired max lift is l = 5mm 17 Δθ= 20 with Δθe=5 (max duration available) ω=3000 RPM => γ = m/s². Today s actuator cannot produce such a high acceleration (γ =3 000 m/s²) Comparison : a traditional camshaft for N=7000 RPM produces : γ = m/s²

18 QUASI DIMENSIONAL ENGINE MODEL.

19 Quasi Dimensional Engine Model Barré Saint Venant Equation 19 Inlet pipe Air tank Exhaust pipe Cliquez pour modifier δqw : Standard les WOSCHNI styles modeldu Qw δqc : Standard WIEBE model texte du Qc masque du δw + δq c + δq w + hi dm i + du = m cv dt + cv T dm δw + δqc + δqw + hi dmi + ho dmo cv T Quatrième dtniveau.. = m cv = h o dm o T dm, = dt i dm o ( 5 majors chemical species : O 2 N 2 C x H y CO 2 H 2 O ) dm m r T V P =

20 20 5 SIMULATIONS RESULTS

21 Simulated Engine Single Cylinder 21 5 valves including one Charging valve Cylinder volume around 400 cm3 Charging valve diameter is around 15 mm

22 Air Tank Pressure : 5 bar Engine speed : 1500 RPM Pneumatic PUMP Mode 22 Valve acceleration : m/s² have been optimized. CRITERION : Maximize the air sent to the tank. 4-Stroke 4-Stroke 2-Stroke full Exhaust Off variable (*) Inlet Open Inlet Close Charging Open For each mode, the opening and closure timings of the charging valve Charging Close Exhaust Open 530 x x 19/05/2008 Exhaust Close 10 x x 1

23 23 Pressure [Pa] 8 x IO CC CO Pneumatic Pump Mode 3 3 IO 2 2 Cliquez ICpour modifier les IC styles du 1 1 EO Volume [m 3 ] x 10-4 Volume [m 3 ] x 10-4 Volume [m 3 ] 4 Stroke Pump 4 Stroke Pump Exhaust Off 4-stroke 4-stroke Exhaust Off Indicated Work J Cinquième Wi ( ) cycle niveau (J/cycle) J EC 4 stoke pump Inlet Open Inlet Close Charging open Charging close Exhaust open Exhaust close SPC () g = m air. tan k g ( ) cycle Pressure [Pa] 8 x CC IO CO 4 stoke pump -Exhaust off Inlet Open Inlet Close Charging Open Charging Close x 10-4 Pressure [Pa] 8 x CC CO 2-Stroke Pump Inlet Open Inlet Close Charging Open Charging Close 2 Stroke Full Variable 2-stroke full variable Pumped Air mass (g/cycle) S.P.C. (J/g) IC

24 Impact of the Valve-train sophistication on the performance of the pneumatic PUMP mode 24 Pumped Air Mass [g/cycle] Troisième 0.05 niveau Quatrième niveau Enine Speed[rpm] N < 1000 RPM => No significant effect 4 Stroke Pump m/s² 4 Stroke Pump m/s² 4 Stroke Pump m/s² N > 1000 RPM => Serious impact of the acceleration on performance

25 25 Pneumatic MOTOR Mode Air Tank Pressure : 10 bar Engine speed : 1500 RPM Valve acceleration : m/s² have been optimized. CRITERION : Maximize the Pneumatic Motor Efficiency J Wi( ) J cycle PME() = g g m k ( ) cycle air.tan 4-stroke 4-stroke Inlet 2-stroke full Off variable Inlet Open -10 x x For each mode, the opening and closure timings of the charging valve Inlet Close 190 x x Charging Open Charging Close Exhaust Open /05/2008 Exhaust Close

26 26 Pressure [Pa] x 105 IO CO CC 4-Strokes Motor Inlet Open Inlet Close Charging Open Charging Close Exhaust Open Exhaust Close Pneumatic MOTOR Mode 4 4 Cliquez pour EO 2 modifier les styles du CO EO 2 EC EC IC EC Volume [m 3 ] x 10-4 Volume [m 3 ] x 10-4 Volume [m 3 ] 4-stroke 4-stroke Inlet Off Quatrième Indicated niveau Work (J/cycle) J Wi Consumed Air Cinquième ( ) J cycle niveau PME () g = m air.tan k g ( ) cycle Pressure [Pa] 10 x CC mass (g/cycle) P.M.E. (J/g) 4-Strokes Pneumatic motor Inlet Off Charging Open Charging Close Exhaust Open Exhaust Close x 10-4 Pressure [Pa] 10 x CO CC 2-Strokes Pneumatic Motor Charging Open Charging Close Exhaust Open Exhaust Close 2-stroke full variable EO

27 Impact of the Valve-train sophistication on the performance of the pneumatic MOTOR mode 27 Indicated Work [J/cycle] Stk. Pneu. Mot. In. Off-1000 m/s² 4Stk. Pneu. Mot. In. Off-3000 m/s² 4Stk. Pneu. Mot. In. Off-5000 m/s² Troisième 20 niveau Quatrième niveau Important loss of Indicated Work for any value of acceleration, as soon as N = 1500 RPM => Pneumatic motor should be used to start and drive the vehicle at low speed.

28 28 6 CONCLUSION

29 CONCLUSION The valve train acceleration is the key to best performance for pneumatic cycles, especially for the pump mode. For higher maximum valve accelerations, the range where pneumatic modes can be used with high efficiency is extended. showed, that a benefit exists in using a disengagable Exhaust camshaft 2. In the case of 4-Stroke modes (motor and pump), it has been disengagable inlet camshaft. Conversely, no benefit has been founded with a disengagable 3. In the case of 2-Stroke fully variable modes, simulations have shown a slight benefit of using them. But the technical complications and the cost generated leave the question of the viability of these solutions open.