400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-5760 Web: www.sae.orgSAE TECHNICAL PAPER SERIES 2004-01-0643 Development of New Generation Hybrid System (THS II)– Development of Toyota Coolant Heat Storage System – Yasuhiro Kuze, Hideo Kobayashi, Hiroki Ichinose and Takayuki Otsuka TOYOTA Motor Corporation Reprinted From: General Emissions 2004 (SP-1863) 2004 SAE World Congress Detroit, Michigan March 8-11, 2004Downloaded from SAE International by University of New South Wales, Sunday, August 19, 2018All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise,without the prior written permission of SAE. For permission and licensing requests contact: SAE Permissions 400 Commonwealth DriveWarrendale, PA 15096-0001-USAEmail: [email protected]: 724-772-4891Tel: 724-772-4028 For multiple print copies contact: SAE Customer ServiceTel: 877-606-7323 (inside USA and Canada)Tel: 724-776-4970 (outside USA)Fax: 724-776-1615Email: Customer [email protected] ISBN 0-7680-1319-4Copyright © 2004 SAE International Positions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE. The author is solely responsible for the content of the paper. A process is available by which discussions will be printed with the pap er if it is publishe d in SAE Transactions. Persons wishing to submit papers to be considered for presentation or publication by SAE should send themanuscript or a 300 word abstract of a proposed manuscript to: Secretary, Engineering Meetings Board, SAE. Printed in USADownloaded from SAE International by University of New South Wales, Sunday, August 19, 20182004-01-0643 Development of New Generation Hybrid System (THS II) TOYOTA Motor Corporation Copyright © 2004 SAE International ABSTRACT As the interest in global environmental protection increases, so do the worldwide social requirements of annually decreasing fuel consumption and producing cleanerexhaust gas. In Califor nia, a new special category of emissions standard, PZEV was implemented, as the most stringent emissions standard in the world. To meet thisstandard, it is crucial to decrease ex haust gas unburned hydrocarbon emissions, especially in cold start conditions. Toyota has sought a new approach to decrease these emissions and developed the Toyota Coolant Heat Storage System (CHSS). This system recovers hot engine coolant, in a heat- insulated reservoir, used for the next cold start, during and / or after engine operation and stores it in a reservoir during the engine-off soak period. During a cold start, the reserved hot coolant is directed to the cylinder head to rapidly warm the intake ports, and reduce enrichment, resulting in much lower HC emissions in cold conditions, This system is adopted on Prius with THS II(Toyota Hybrid System II), launched in August 2003, complying with California’s ATPZEV, one of cleanest carcategor ies in the world. INTRODUCTION Fig. 1 illustrates a generic vehicle heat balance showing that as much as two- fifths of the fuel energy is wasted as lost heat energy in both the exhaust gas and coolant heat transfer to the environment. After much research to determine the most useful heat to recover, Toyota has developed a system that recovers and utilizes the wasted heat energy from the engine coolant heat. Exhaust gas heat is high temperature and low density but needs to be converted to be utilized, a process involving many losses.For example, convert it to coolant heat with a heatexchanger or to electric energy with a thermoelectric element. Because the coolant heat is relatively low temperature and high density, it is much easier to recover and use, so it was decided to recover this wasted coolant heat energy. Methods were then explored to store the recovered heat. There are two primary methods. One