International
Japanese auto makers face tough new emission standards Patterned after U.S., ceilings are one tenth earlier limits for hydrocarbons and CO, half those for nitrogen oxides Michael K. McAbee C&EN, Tokyo Next week Japan's 1975 automotive emission standards come fully into ef fect. Patterned after the U.S. statutory standards that also originally were in tended for 1975 enforcement, the new Japanese emission ceilings are one tenth the previous limits for hydrocar bons and carbon monoxide and about half the earlier figure for nitrogen ox ides. The tighter standards have ap plied since April to any new models in troduced by Japanese auto makers, who don't make a rule of annual model changes. From Dec. 1, the 1975 limits will apply to virtually all passenger car output for the domestic market. Stric ter than current federal emission stan dards for hydrocarbons and CO in the U.S., the Japanese standards are some what easier on NO x . But 15 months down the road lies a further 25 to 50% reduction, depending on vehicle size, in the Japanese NO x limit. The response by Japan's nine auto makers has been far from uniform. As early as June 1973, Toyo Kogyo Co. had a rotary-engine Mazda in the showrooms that met the 1975 stan dards, and by that year's end both Toyo Kogyo and Honda Motor had in troduced reciprocating-engine models that met them as well. But the two majors -Toyota Motor and Nissan Motor, whose combined share of Ja pan's auto market last year was about 70%—waited until this fall to bring out most of their cleaner-engine models. By the time this year's Tokyo Motor Show got under way earlier this month, most of the industry's new range of autos were on display. Catalytic con verters, thermal reactors, and several lean-burn engines are being used to cope with the new emission limits. Some makers also claim success in off setting the drop in fuel economy that usually accompanies exhaust cleanup. And the new lines of four makers al ready meet the 1976 NO x limit. 14
C&EN Nov. 24. 1975
How stiff are Japan's new emission standards? The intent, when average permissible emission rates were set three years ago for 1975 enforcement, was that they should be as strict as the limits provided for the 1975 model year by the U.S. Clean Air Act amendments of 1970. The U.S. limits, except that for ΝΟχ, were later postponed to the 1977 model year, and now have been delayed even further. But the Japanese government resisted industry pressure to emulate the U.S. delay, citing Ja pan's greater traffic concentration and thus heavier automotive air pollution. (Some 12.8 million cars, trucks, and buses were registered in California in 1972. The figure for Japan, which is somewhat smaller than California, was 22 million.) Yet the 1975 Japanese emission stan dards that emerged are difficult to compare exactly with U.S. limits, be cause they are tied to different test procedures (C&EN, April 28, page 16). Both the U.S. Environmental Protec tion Agency and Japan's Ministry of Transport use a chassis dynamometer to simulate typical driving patterns statically. The U.S. procedure first runs a test car through a "trip" from a cold start, then after a short wait re peats the "trip" from a hot start. A weighted average is made of emissions from the two sequences, based on EPA's estimate of the ratio of hot to cold starts in a typical driver's day. The Japanese cold- and hot-start tests are not run in sequence, and the two "trips" follow different driving pat terns. Results are reported separately. To get a rough comparison of strin gency, EPA has run two U.S. autos—a compact and a standard-size car —through both the U.S. and Japanese test sequences. Though direct, such comparison isn't exact. For one thing, notes an automotive engineer in Tokyo, the Japanese test is intended for do mestic models. Some features, such as carburetor setting, that bear on emis sion levels, differ from those of U.S. cars or Japanese export models. Still, EPA's comparison indicates that the 1975 Japanese standards for hydrocar bons and CO are markedly stricter than current U.S. standards. A car that exactly meets the Japanese limits, EPA estimates, would register about 1 gram per mile of hydrocarbons by the U.S. test and about 8 grams per mile of CO. The U.S. limits are 1.5 and 15 grams per mile, respectively.
Most of auto industry's new offerings were on display at Tokyo Motor Show Such a car would show about 3.7 grams per mile of NO x in the U.S. test, EPA adds, or close to 20% above the U.S. limit. But Japan's upcoming 1976 NO x standard, which will apply to all auto production from March 1977, will cut the hot-start NO x limit in half for cars up to about 1 ton and by some 30% for heavier cars. The U.S. NO x limit is itself scheduled for a 35% re duction in 1977. Honda, whose Civics already meet the 1976 Japanese NO x standard, told EPA early this year that its stratified-charge engines, with some retuning, probably can meet the 1977 U.S. NO x limit too. Toyo Kogyo got a head start in emis sion cleanup since rotary engines pro duce markedly less NO x —the hardest to control among exhaust pollu tants—than do reciprocating engines. Toyo Kogyo, after developing practical rotaries from NSU-Wankel designs, has been building rotary-engine autos since 1967. In June, its rotary models were the first autos to meet the 1976 NO x standard in official testing. A thermal reactor removes hydrocarbons and CO from the exhaust of these rotaries. To meet the 1976 NO x limit, a power valve was adopted for the carburetor, making possible better control of the fuel/air ratio. In October, Toyo Kogyo also rolled out five lines of reciprocating-engine cars that meet the 1976 NO x standard in advance. These engines use thermal reactors and exhaust gas recirculation to the cylinders for emission control. Mitsubishi Motors, now a joint venture of Mitsubishi Heavy Industries and Chrysler, also is taking the thermal re actor route. A system of reactor, ex haust gas recirculation, and engine modifications enables Mitsubishi to meet the 1976 standard for its whole line of small- and medium-size autos. Their introduction began last month. Honda's Civic compacts, having met
the 1975 emission standards two years ago, were revamped to clear the 1976 ΝΟχ limit last August. The firm's CVCC (compound vortex controlled combustion) engines cut the amount of pollutants formed in the engine rather than removing them from the exhaust. Fuel is charged as a small amount of rich mixture to an ignition chamber and a larger amount of lean mixture to the cylinder itself. The rich mixture ig nites easily and expands into the cylin der. The lean mixture, once it's burn ing, affords slow, even combustion. Temperature of combustion and avail ability of air at all stages of the cycle promote complete burning of fuel and reduce CO and NO x formation. Another approach to lean-burn com bustion is taken by Fuji Heavy Indus tries. Its compact Subaru autos are fit ted with flat-four (two pairs of horizontally opposed cylinders) engines that, like Honda's CVCC, already are within the 1976 NO x limit. Instead of a separate ignition chamber, a suction valve draws extra air into the exhaust port as spent gases leave the cylinder and into the cylinder itself as the induc tion stroke begins. No exhaust treatment is needed. Subaru models fitted with this engine went on sale last month in Japan. Both Toyota and Nissan (maker of the Datsun line) have put their money on catalytic converters. So has Isuzu Motors, in which General Motors holds 34% equity. Toyota's new models, for example, meet the 1975 CO and hydro carbons limits handily. Average NO x emissions of these cars in the hot-start
test range from 1.05 to 1.9 grams per mile. (The 1975 limit is 1.93 grams per mile.) Toyota expects to market some models that meet the 1976 NO x limit in first-quarter 1976. Some will use catalytic converters, others a Toyota lean-burn engine. Nissan has catalytic converter-equipped models ready for government testing that are expected to meet the 1976 standard. The Japanese will be buying cars with cleaner engines, but at some pen alty in purchase price and fuel econo my. Nissan's autos, for instance, will be priced about 10% higher on average than equivalent models that did not meet the 1975 emission limits. Toyota's new Century—an 8-cylinder, 2-ton car —got 20 miles per gal in the Transport Ministry's standard fuel economy test. The previous Century got 21.2. But both old and new models of Toyota's 6-cylinder Crown 2000 got 29.4 miles per gal. Mitsubishi Motors last year fielded two models—Colt Galant and a Celeste —that met 1975 standards. But the exhaust cleanup system raised fuel consumption 10% for one, 5% for the other compared with the same models before changeover. Mitsubishi has met the 1976 NO x limit in its new models by raising the amount of exhaust gas recirculated to the engine. At the same time, a control system was added that adjusts recirculation rate to engine speed. This, the firm says, cuts fuel demand 5 to 7% compared with last year's Galant and Celeste. The sharpest recovery in fuel econo my has been in Toyo Kogyo's rotaries
(C&EN, Nov. 17, page 6), which, though clean, had been notoriously heavy on gas. New rotary models brought out last month get close to 40% better gas mileage than did the 1973 engine, because of better gas seal ing and other changes in the engine's combustion chamber, improved insula tion around the exhaust port, and pre heating of air injected into the after burner. As an incentive to both makers and buyers, there's a 40% cut in purchase tax for Japanese buyers who choose a model meeting the 1976 NO x limit. The deduction decreases after firstquarter 1976 and ends next August. The maker also gets a small reduction in commodity tax on such models. Toyo Kogyo's rotary-engine Cosmo, for example, sells in Tokyo for about $6100. The buyer saves about $270 on his purchase tax. A similar tax incen tive applied to models that met the 1975 standards earlier than required, but the consensus is that it wasn't a very effective inducement to buy cleaner cars. Indeed, Japanese auto output in recent months neared record levels as some makers built up inven tories before the required date of changeover to costlier models under 1975 emission standards. Makers who haven't anticipated the 1976 NO x limit now have a breathing space until March 1977, although any new models brought out after next April 1 must meet it. Japan's Environment Agency, meanwhile, still hopes to enforce an other lowering of the NO x ceiling, 60 to 70% in 1978. D
Auto makers use variety of cleanup systems to meet Japan's strict emission limits Maker
Model
Body type
RPM at which horse Horse power power* generated
Number of cylinders
Engine displace ment (cu in)
8 8 2-rotor 6
269 206 40 X 2 122
200 170 135 115
Weight (lb)
Emission control system
Miles per gal1
4800 5400 6000 5600
4125 4135 4080 3220
Catalyst Catalyst Thermal Catalyst
22.6° 20.0" 21.2C 34.1
Nissan Toyota Toyo Kogyo Nissan
President Century Roadpacer Cedric
4-door 4-door 4-door 4-door
Toyo Kogyo Toyota
Luce Wagon Crown
2-rotor 6
40X2 121
135 125
6000 6000
2780 3135
Thermal Catalyst
25.9
