Internal combustion engines in cars may be on their way out, but experts agree it will take a few decades before electric-powered vehicles become dominant. Meanwhile, the existing gas and diesel engines can be made more efficient and less polluting. With a $9 million grant from the U.S. Department of Energy, a U.S.-based company is using an old technological concept to build a power train that is 50 percent more fuel-efficient and just as powerful as conventional engines.
This little engine looks like it has only three pistons, but in fact, it has six, sharing only three cylinders.
With the help of modern technology California-based Achates Power has given new life to the concept of the opposed-piston engine, mostly abandoned after the second World War.
“With the opposed-piston engine, you're able to achieve the efficiency of a much larger engine in a much smaller package," said Fabien Redon of Achates Power.
An opposed-piston engine is a two-stroke engine with separate oil flow. It has no cylinder heads and no valves, both sources of considerable loss of heat and power in conventional combustion engines.
Two pistons move against each other in the cylinder, compressing a fuel-air mixture, which self-ignites, pushing the pistons apart, generating power.
Exhaust gases escape through ports in the cylinder walls.
Stripped of many conventional engine parts, the opposed-piston engine is inexpensive and simple to manufacture.
“We make sure that we do not over scavenge and achieve a very good combustion efficiency, so that hydro nitro-carbons and the emissions are reduced to a great extent," said Redon.
Larger opposed-piston engines have long been used for military and other applications. But developing them for consumer vehicles was not easy.
“This combustion strategy has some difficulties and weaknesses at low loads, because it needs a certain level of temperature inside the combustion chamber to make sure that the gasoline gets ignited," said Redon.
Achates Power, together with Argonne National Laboratory and Delphi Automotive, say they are sure they will overcome the obstacles, and by 2018 will have a 50 percent more efficient three-liter three-cylinder engine that will be suitable for passenger cars and trucks.
北师大版英语七下《Unit 8 Seasons and Clothes》(Lesson 29)ppt课件(2)
2016春北师大版英语八下Unit 6《Lesson 18 The Mystery Writer》(第2课时)ppt课件
北师大版英语七下《Unit 2 On the Weekend》mp3听力原文
北师大版英语七下《Unit 9 People》(Lesson 33)ppt课件
北师大版英语七下《Unit 8 Seasons and Clothes》(Lesson 29)ppt课件(5)
北师大版七年级英语下学期 unit 20 sports
北师大版英语七下《Unit 10 In the Past》(lesson37)ppt课件
北师大版英语七下《Unit 12 China》(Lesson 47)ppt课件(1)
北师大版英语七下《Unit 1-5》ppt单元复习课件
北师大版英语七下《Lesson 2 A Dangerous Job》ppt课件
北师大版英语七下《Unit 1 Daily Life》mp3听力原文
北师大版英语七下《Unit 8 Seasons and Clothes》(Lesson 31)ppt课件
北师大版英语七下《Unit 8 Seasons and Clothes》(Lesson 32)ppt课件
2015春北师大版英语七下Unit 1《Lesson 2 A Dangerous Job》ppt课件
北师大版英语七下《Unit 12 China》(Lesson 47)ppt课件(2)
北师大版英语七下《Unit 11 Vacations》(Lesson 44)ppt课件
北师大版英语七下《Lesson 9 Food for Sport》ppt课件
2015春北师大版英语七下Unit 1《Lesson 1 After School》ppt第1课时教学课件
北师大版英语七下《Unit 12 China》(Lesson 45)ppt课件(2)
2016春北师大版英语八下Unit 6《Lesson 18 The Mystery Writer》(第1课时)ppt课件
北师大版英语七下《Unit 8 Seasons and Clothes》(Lesson 29)ppt课件(3)
2015春北师大版英语七下Unit 1《Lesson 1 After School》ppt第2课时教学课件
北师大版英语七下《Unit 8 Seasons and Clothes》(Lesson 32)ppt课件(1)
北师大版英语七下《Lesson 4 Helping at Home1》ppt课件
北师大版英语七下《Lesson 16 My Favourite Animal》ppt课件
北师大版英语七下《Unit 9 People》(Lesson 33)ppt课件(1)
北师大版英语七下《Unit 12 China》(Lesson 45)ppt课件(1)
北师大版英语七下《Unit 11 Vacations》(Lesson 42)ppt课件
北师大版英语七下《Unit 4 Seasons and Weather》mp3听力原文
北师大版英语七下《Lesson 6 Going Out》ppt课件
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |