The Problem of Single Cylinder Diesel Engine With National III Standard

Nowadays, the huge limit for the National III standard emission of the whole machine of agricultural machinery is approaching. After the practice test in one production season of this year, the main engine plants’ and users’ confidence is largely improved, which is so true for mating of the multi-cylinder engine only.

However, how is the single cylinder engine’s preparation? It seems that rare people focus on this. In fact, the single cylinder diesel engine is confronted with more problems in upgrade compared with the multi-cylinder diesel engine. So far, any product of the single cylinder diesel engine with the power lower than 8kW has not passed the type approval for National III standard emission and all air-cooled and mechanical pump single cylinder engines have not passed the type approval.

Therefore, for the single cylinder diesel engine with the bad industrial situation originally, the National III standard upgrade is even an ordeal which is not inferior to the death ordeal. In the meantime, the downstream industries involved, such as mini-tiller and rice transplanter etc. will be faced with terrible blow thereby.

So, what kinds of difficulties that the multi-cylinder engine does not have will the single cylinder engine be confronted with? What kinds of influences will have?

More severe problems in upgrade compared with the multi-cylinder engine

1. High technical route requirements of the type approval for National III standard emission

The validation test must be carried out when the competent department for type approval thinks that there is the technical route scheme that may not reach the standard. From the perspective of application process specified by the Ministry of Environmental Protection and the audit situation, the mechanical pump diesel engine also shall complete the validation test even though its emission allowance is large enough, besides the 750-hour durability test. The validation test also needs to be carried out on the electronic controlled diesel engines with the technical route which is not universally adopted in the industry.

Due to the structure and product market positioning, single cylinder engines mainly adopt the mechanical pump and the electronic unit pump as the technical route, which makes validation test need to be carried out on most single cylinder engines.

In the meantime, the endurance test shall be carried out for follow-up remaining time only after all indexes are qualified according to the test time interval and the emission test carried out after completion of 300-hour durability bench test. For the 0-hour emission test of the validation test of the mechanical pump diesel engine adding the post-processing equipment, it is required to be completed without the post-processing equipment so as to verify the actual effect of the in-engine purification measures for the diesel engine.

2. Low passing rate of type approval for National III standard emission

It is understood that only water-cooled electronic unit pump has passed the type approval for the National III standard emission, had the power above 8kW and had the relatively mature technology for the single cylinder engine so far. In all water-cooled electronic unit pumps passing the type approval for the National III standard emission, their domestic manufacturers include Changchai, Changfa Group, Jiangdong Group, Shandong Huayuan Laidong Engine Co., Ltd. and Shandong Clean etc.

Any product of the single cylinder diesel engine with the power lower than 8kW has not passed the type approval for National III standard emission and all air-cooled and mechanical pump single cylinder engines have not passed the type approval.

Air-cooled single cylinder engine: the air-cooled electronic unit pump has large difficulties in passing the type approval for National III standard emission according to the current technical route; the duration of the endurance test is 750 hours and the last emission value exceeds the limiting value, the reason of which mainly is that the air-cooled heat value is higher than the water-cooled heat value and thus the temperature of the engine oil is slightly high, the tight fit forms and the fatigue occurs.

At present, the final emission test is being carried out by the existing enterprises of the air-cooled common-rail single-cylinder diesel engine and it seems to be successful in sight. However, only rare models including 186/188/192 etc. have the power above 5.5kW, but they cannot cover the power section lower than 5.5kW. In the meantime, the common rail places extremely high requirements on the oil quality. But, it is difficult to guarantee domestic oil quality and rural habit of using oil.

Mechanical pump single cylinder engine: some foreign enterprises such as Kubota and Yanmar etc. have passed the type approval for National III standard emission. But, all domestic manufacturers of the mechanical pump diesel engine including multi-cylinder engine have not passed the type approval for National III standard emission so far. According to the current technical route, the endurance test of the mechanical pump single cylinder engine needs to spend 750 hours. But enterprises reflect that deviation of some parameters such as power and torque etc. will occur after 300～350 hours and the manufacturing accuracy of oil limiter (oil regulator) is very high, but there is a deviation of the repeated accuracy on maximum torque point.

3. Large increase of cost

Water-cooled single cylinder diesel engine: at present, the minimum power of the water-cooled electronic controlled single cylinder diesel engine passing the type approval for National III standard emission is 8.8kW, which conforms to the ministry-level power requirements popularized and appraised for the walking tractor. In the absence of the post-processing equipment, each cost of it is 1000 yuan more than that of the water-cooled electronic controlled single cylinder diesel engine passing the type approval for original National II standard emission. In addition, each cost will increase by 500～800 yuan after batching, thus the cost increases by about 50%.

Air-cooled single cylinder diesel engine: cost of the Nation II standard air-cooled single cylinder diesel engine is only 1500～2000 yuan/set. At present, only common-rail single cylinder diesel engine is promising to pass the type approval for National III standard emission for air-cooled single cylinder diesel engines. But the cost of air-cooled common-rail single cylinder diesel engine is 3000 yuan/set at least and is double in terms of cost. In addition, high oil quality is proposed for the electronic controlled and common-rail air-cooled single cylinder diesel engine and the mechanical use cost of the electronic controlled and common-rail air-cooled single cylinder diesel engine increases largely.

The mating of single cylinder engine mainly adopts the small-sized agricultural machinery. For the small-sized agricultural machinery, its products have a lower unit price and its power section cost is the most, thus, increase of power cost has extremely large influences on the cost of the whole engine. However, the mechanical pump single cylinder engine with lower increase of cost does not pass the type approval for National III standard emission.

4. Difficult supervision of auxiliary products of the single cylinder engine

In contrast, there are announcement management of the Ministry of Industry and Information Technology of the People's Republic of China or license plate management of the Ministry of Transport in other industries, so other industries have the high threshold and are relatively standard. While, emission supervision for the agricultural machinery is the most difficult, reasons of which are as follows: firstly, the rural areas are vast. Especially, the supervision scope is difficult to touch the remote mountain areas; secondly, the peasants’ awareness of environmental protection is weak, the reason of which is that the peasants have the weak purchasing capacity, thus purchasing the products with cheap price, good service performance and convenient maintenance becomes the absolute truth for them and thus the environmental protection is ignored.

From the perspective of the monthly sales statistics report of diesel engines of August in this year, the decreasing extent is obvious compared with the first half year. From August, the diesel engines are difficult to sell basically in domestic market, thus the decreasing extent of the whole year is enlarged.

Due to influences of the allowance for purchasing agricultural machinery and influences of hysteretic nature of the production and manufacturing, inventory digestion and the situation that the sale of the agricultural machinery keeps up with farming season etc., the main engine plant has dared not to purchase and assemble the diesel engines with the National II standard emission since July and August.

It can be seen that in the condition that there is not the allowance for the diesel engine, the agricultural machinery departments do not check the condition. But the main allowance market is still the main engine market and all sets of engines are checked. Thus, the allowance policy for purchasing agricultural machinery is the true trump card for implementation of National III standard emission.

However, in terms of the mini-tiller — main auxiliary product of the single cylinder engine, there is the allowance for it, but the amount is low. In the meantime, at present, there has not been a qualified auxiliary product of the diesel engines with the National III standard emission, so the supervision difficulty is very large.

Industry of the single cylinder engines and its auxiliary products will experience the heavy blow

Main auxiliary products of the single cylinder engines with the power lower than 8kW are mini-tiller and one-wheel ride type rice transplanter, in which quantities of the mini-tillers for the single cylinder engines account for 70% of the total quantities.

So far, all products of the air-cooled single cylinder diesel engines have not passed the National III standard type approval, so mini-tillers and one-wheel ride type rice transplanters etc. matching for the diesel engines will not enjoy the national allowance after December 1.

For the single cylinder engine and the mini-tiller, they will be confronted with problems covering five aspects after National III standard upgrade under the condition that the diesel engine is still the main mating power of the mini-tiller.

Firstly, affect usage of state allowance. Especially in some provinces in south of China, the allowance is abundant originally and the allowance for the mini-tillers for the diesel engine account for major part. Thus if there is not the product allowance application meeting the requirements, more remaining allowance will occur. 

Secondly, remain vigilant against the situation that the market is full of “three-without goods”. If there is not the allowance, there will not be the important guarantee of supervision. But the supervision difficulty is very large if relying on the manufacturing and circulating links. So it can be predicted that people will be flocking to buy the mini-tillers and matched single cylinder diesel engines for the “three-without goods”.

Thirdly, the situation that bad money drives out good money will occur. There is the strict management for the financial incomes and expenses of the large enterprises, otherwise, the risks of tax evasion will exist and the price is too large if the large enterprises are investigated due to violation; while, the small enterprises may make no scruple, which is a kind of impact for the standard enterprises. It is estimated that the standard manufacturing plants for single cylinder diesel engines and mini-tillers will also provide non-national III standard “accessories” for the market to make the dealers and users “assemble” by themselves, but the profit will be extremely low.

Fourthly, there will be large impact for industry. If the market is full of “three-without goods” with the worse safety performance, the gradual standardization result in recent years of the mini-tiller industry will be fall short of success for want of a final effort and the purchasing desire of the peasants who do not enjoy the allowance will be very low. Thus, the mini-tiller industry will suffer from adverse impact whether in the aspect of industrial standardization or the market demands etc. For domestic market of the single cylinder engines with the power lower than 8kW, it will also suffer from the heavy blow. If there are not the foreign markets and supplement of multi-cylinder engines and the gasoline engines, the industry will be difficult to survive if only relying on manufacture of single cylinder engines.

Fifthly, the enterprises’ popularization, authentication and allowance application will be affected. Because the National III standard emission type approval certificate for the matched diesel engines cannot be submitted, the popularization and authentication application cannot be handled. According to the requirement that the extension application of the popularization and authentication certificate shall be made six months before the expiration of the certificate, the extension will not be made in time and the application will not be made as per the first authentication, thus the time cost caused will not be retrieved.