New technology leads construction machinery to new development

In recent years, with the successive introduction of the Tier4 emission standard in the United States, the European IIIB emission standard, and the China National 4 emission standard, how should construction machinery be used as a large emitter to achieve the goal of energy conservation and emission reduction? The promotion of new power sources will surely bring new changes and opportunities to the construction machinery industry along with the general trend of environmental protection.

New technologies help diesel engine energy-saving and emission-reduction diesel engines have been widely used in various types of construction machinery and equipment because of their low-speed high-torque and near-perfect engine performance curve. However, with the recent global energy shortage and environmental protection awareness, traditional The low utilization, high emission, and loud noise of diesel engines have begun to attract the attention of the industry and society. In response to the new development trend, various new technologies and new products for the energy saving and emission reduction of diesel engines have also emerged one after another. For example, now the project Common diesel common rail, EFI, and EGR (exhaust gas recirculation) on mechanical diesel engines.

Diesel common rail is the most common "sign" in environmentally friendly engines

Diesel common rails provide ultra-high pressure diesel fuel to injectors (pressure up to 100MP or more) under the influence of new high-pressure pumps, engine control units and various types of sensors. At the same time, high-pressure common rails act as fuel for the injectors. The role of force. Therefore, diesel engines with high-pressure common rails are better atomized than conventional diesel engines to provide stable pressure diesel, so that more efficient combustion can be used to increase the efficiency of diesel use.

Because diesel common rails have the function of holding pressure and pressure, the requirements for system sealing are extremely strict. Once the pressure leaks in the system, the engine will not work.

The EFI injector injects the EFI injector into the combustion chamber more precisely. Under the control of the electrical unit, the fuel can be supplied and shut off in time and accurately according to the set marking to achieve the best injection time and fuel injection quantity. control. The traditional fuel injector is a mechanical type. When the high-pressure pump supplies fuel to the cylinder, the fuel injection is stopped and the fuel injection is stopped. Therefore, the use of the electronic fuel injection system will save more diesel than the traditional fuel injector.

Although the EFI injector can accurately perform diesel injection, compared with the direct injection injectors in the past, the structure is complicated, the cost is relatively high, and the quality of diesel oil is demanding, and the domestic diesel tagging is relatively low compared to the developed countries. In particular, the diesel produced by some small refineries is difficult to meet the requirements of the EFI injectors. Therefore, the EFI injectors are often damaged due to diesel during their use in the country. In addition, the electronic control methods also increase the probability of failure and Maintenance difficulty.

EGR system assists diesel engine in energy saving and emission reduction upgrading The EGR system (exhaust gas recirculation) is a common additional device in construction machinery. It can capture a part of the exhaust gas after combustion, and it can be used under the action of original components such as coolers and electronic control valves. The mixed gas which is not fully utilized in the first combustion is sent to the cylinder for combustion together with the fresh air, and since the exhaust gas contains a large amount of CO2, the CO2 cannot burn but absorbs a large amount of heat, so that the mixture in the cylinder is combusted The temperature decreases, which reduces the amount of nitrogen oxides produced. Increased fuel utilization while significantly reducing harmful gas emissions.

Therefore, under the “help” of new technologies, diesel engines not only achieved the goal of saving fuel and reducing emissions, but also met the new standards for emissions, and were recognized by major host manufacturers.

"New Power" is promising for the construction machinery market in the future. At the 2013 CTO Forum, Cao Donghui, president of the Sanyueji Research Institute, stated in the report on energy saving and emission reduction technology of excavators that "With the rapid development of the economy, the problem of energy shortage has become increasingly prominent. The research on energy-saving technologies for excavators with large energy consumption is urgently needed. According to the “Statistical Communiqué of the People’s Republic of China on National Economic and Social Development in 2011”, the single displacement of construction machinery is 4-8 times that of cars, and the annual fuel consumption of construction machinery is The total amount is about 90% of the civilian cars (49.62 million units).At present, major excavator manufacturers at home and abroad have invested a lot of energy in the research of energy-saving technologies. The power components include hybrid and new energy (electric and natural gas power). )".

At present, the commonly used hybrid power of construction machinery can be roughly divided into:

Oil-electric mixing (electric slewing motor instead of hydraulic slewing motor), oil mixing (recovering and storing hydraulic energy and other forms of energy, for auxiliary mechanical action) and oil-electro-hydraulic mixing.

Because hybrid power can reduce the degree of machinery's "dependence" on diesel engines and optimize the overall performance of the machinery, hybrid power has great potential for development in the future, but on the one hand, hybrid power is difficult to develop and covers a wide range of characteristics. On the other hand, due to the fact that its related supporting technologies are still not perfect and the market lacks trust, the hybrid power has experienced many years of development, but its market sales are still at a relatively early stage.

The “world pattern” of hybrid technology is still dominated by foreign brands, such as the Liebherr (European Department) Liebherr exhibited at the German BMW 2013 exhibition; In 2012, the company released the first hybrid excavator Cat336E H at the Industrial Design Center in Mossville; (Japan) Komatsu sold HB205, HB215 hybrid power for the Chinese market, and some domestic From host manufacturers such as SWE230S Hybrid, Zoomlion (ZE205E-H1), and SY215C Hybrid, they also exhibited their own new hybrid excavator products as early as around 2010 ( Mainly oil and electricity, but domestic companies are still difficult to achieve mass production and sales due to their own research and development capabilities and market environment.

The new energy aspects of construction machinery are mainly electric and LNG (liquefied natural gas).

The electric drive is replaced by a large electric motor instead of an engine drive, and is used in large-scale mechanical products, such as Hitachi's EX3600 (with a bucket weight of 21-23 cubic meters with a full weight of 360t) and EX5500 (with a total bucket weight of 550 tons with a weight of 27 cubic meters). EX8000 (800t full-load bucket capacity 40 cubic meters) hydraulic excavators are used in electric drive. Its advantages are cost-effective, non-emission, and the use of hydraulic systems common to engine-driven excavators, as well as the same hydraulic walking and front-end working devices, and fully inherited the advantages of high efficiency, mobility and other advantages of engine-type hydraulic excavators. , but less used in small and medium-sized construction machinery.

Natural gas engines use natural gas (mainly composed of methane) as the power source. Currently, there are two types of gas supply methods: liquefied natural gas (LNG) and compressed natural gas (CNG). LNG is superior to CNG in terms of power, safety, endurance and maintenance costs. Therefore, LNG is more suitable for use on excavators than CNG.

And there are several advantages in the use of natural gas engines: 1. Small changes 2. Low cost of use (35% - 40% savings compared to diesel) 3. Wide range of product tonnage 4. Less than diesel engine failure rate (statistics Data), Lower maintenance costs 5. Exhaust gas is cleaner than diesel engines.

However, natural gas engines also have some problems that need to be solved. For example: 1. LNG engines have a gap in power performance compared with diesel engines of the same grade. 2. Fuels show inaccurate accuracy 3. Limitations of unsuitable confined spaces (volatility problems in confined environments 4. The natural gas filling equipment needs special design. It is difficult for LNG to fill the site at the present time. This restricts the large-scale promotion of LNG to a certain extent, but natural gas is a clean energy that can replace petroleum in the future. One of them has broad application prospects, and there are a lot of natural gas resources in China. It is believed that with the upgrading of related supporting technologies and the popularization of natural gas energy, the future LNG products will have a vast market space and use space.

LNG loaders or heavy-duty trucks or cars that will lead the energy-saving and environmentally-friendly environment of China's engineering machinery and are powered by natural gas are no stranger to many people, and LNG loaders are very different from heavy trucks and automobiles, similar to heavy trucks. The equipment is mainly driven by the road surface. Its load during the work process is relatively stable, and not only does the loader have a lot of walking during the working process, but at the same time, the hydraulic working device at the front end also frequently performs various load carrying operations, so the load of the loader It is always changing, especially when a large number of hydraulic systems are used (hydraulic fluctuation characteristics are sharp), so the loader requires the LNG engine to be able to transform from high speed to low speed and high torque in the shortest time. It also needs to be based on The characteristics of LNG are specially designed and considered, such as the design of gas circuit, the design of the location of the tank, and the design of safety, so there are more technical problems for the enterprises that produce LNG loaders that need to be tackled.

Although the LNG loader is still in a relatively elementary stage, the current LNG loader can be mass-produced and sold, demonstrating the feasibility of the promotion and application of LNG power in earth-moving construction machinery, and passing an independent innovation to Chinese construction machinery companies. Positive energy, such as the XCMG LNG loader in the world's first application and the first batch sales, (Xugong launched the world's first LNG loader at BICES 2011, and in 2012 to achieve LW600K-LNG, LW800K-LNG The two new models are off-line and mass sales. LOVOL adopts reliable, complete, comfortable and economical LNG loader products (50 series: FL956F-ETX).

In addition, LNG has also been well applied in concrete machinery. Zoomlion, Sany Heavy Industry and CIMC Lingyu have also introduced a variety of mature concrete mixers, such as Zoomlion ZLJ5256GJB3 Three Bridge 12F Dongfeng. The LNG chassis mixer truck, Sany Heavy Industry SY310 C-6W 3Bridge 10-party mixer truck and Lingyu mixer truck use the 6x4 drive chassis model DFL5250GJBA6 with optional 10 and 12-square tanks.

The continuous efforts and achievements made by Chinese branded host companies in the development of LNG products have not only inspired Chinese construction machinery companies to continue to advance on the road of independent innovation, but also showed that Chinese construction machinery companies have real innovation capabilities. From this we believe that China's engineering machinery companies will pass the test of time and practice and will gain more achievements in the field of diesel engine cutting-edge technology and new energy technology, leading China's construction machinery to a broader “blue sky”.