Future development trend of energy-saving control technology for hydraulic excavators
From the perspective of domestic and international development, the energy-saving control of hydraulic excavators has the following development trends:
1) Electro-hydraulic proportional control intelligent
Electro-hydraulic proportional control began to be applied to construction machinery in the early 1980s and has been widely used in hydraulic excavators. The electro-hydraulic proportional technology is used in construction machinery, which can eliminate complicated and huge hydraulic signal transmission pipelines, and transmit hydraulic parameters by electric signals, which not only can accelerate the system response, but also make the control of the entire excavator power system more convenient and flexible. After entering the 1990s, with the development of computer technology, electro-hydraulic proportional control has become more "intelligent", and the application of electro-hydraulic proportional pumps and proportional valves has increased, resulting in the emergence of "smart hydraulic excavators."
This kind of intelligence is mainly reflected in the following aspects. First, the computer can automatically monitor the operating parameters of the hydraulic system and the diesel engine, such as pressure, diesel engine speed, etc., and can automatically control the entire excavator power system to operate in an energy-efficient state based on these parameters. Secondly, it can complete some semi-automatic operations, such as leveling, slope trimming, etc., the driver's proficiency requirements are reduced, but the quality of work can be greatly improved. Third, it is possible to perform fault diagnosis based on the monitored operating parameters to facilitate the maintenance of the excavator. The emergence of these functions has greatly improved the performance of the excavator.
2) Diesel electromechanical spray control
In the traditional mechanical speed control diesel engine, the circulating oil supply amount and the fuel injection advance angle of the fuel injection pump are all affected by the rotational speed, which makes it difficult to further improve the performance of the diesel engine. After the application of the EFI control on the diesel engine, the circulating fuel supply and the fuel injection advance angle of the pump can no longer be affected by the rotational speed, so that the excavator can always work at an optimum state and accelerate the response speed. The development of diesel electromechanical spray controller is an important part of improving the energy saving of excavators.
3) Load sensing control will continue to develop
Load sensing control began in the 1970s, and various engineering machinery hydraulic parts manufacturers have launched a series of related products. This system has good energy efficiency and maneuverability, and even unskilled drivers can adapt quickly. The emergence of proportional flow distribution valves further promoted the application of load sensing technology on excavators, further improving the maneuverability of excavators and solving the problems caused by the lack of skilled drivers in Western countries. Therefore, the demand for load sensing control excavators in developed countries will further increase.
4) Six-way multi-way valve continues to exist
Although load sensing systems with four-way valves provide precise operation, not all operations require precise operation, and skilled drivers can perform precise operations with non-load sensing system excavators. More importantly, the higher price of the load sensing system limits its application in developing countries. At present, many famous excavator manufacturers in the world include load-sensing excavators using four-way valves and excavators using six-way valve hydraulic systems such as positive flow and negative flow control. Proven manufacturing technology and low prices will continue to make the six-way multi-way valve work.
5) Further improve valve control and energy saving control
In the hydraulic system using the six-way multi-way valve, there are still many areas that can be improved, such as maneuverability, energy saving, etc., and various excavator production plants are still under study.
6) Multi-functional combination
In order to improve the performance of excavators, the combination of various energy-saving measures will be more extensive. In the past systems, a variety of functions have been integrated on the hydraulic pump, but due to various conditions, generally no more than three. For example, in hydraulic pumps, pressure cut-off, positive flow control and power limiting functions are integrated. Currently, various hydraulic pump schematics on the market are integrated with various functions. With the development of hydraulic technology, it is possible to integrate more functions on the pump.
7) Variable parameter control
In order to make the excavator better adapt to the load requirements under various working conditions, the setting parameters of some control components inside the power system will no longer be fixed values, but can change with the specific working conditions of the excavator. For example, on the EX series excavators produced by Hitachi Construction Machinery, the pressure difference of the pressure compensator on the load sensing valve can be changed with the working conditions, which enhances the adaptability of the excavator during operation. It can be predicted that in the future excavator power system, more control parameters will be adjusted, which makes the excavator work more efficiently and easier to operate.
8) Pump-engine matching control will be further "intelligent"
With the help of computer control technology, the matching control between the pump and the engine will further realize “intelligenceâ€, and the combination between the two will be closer and achieve integrated control. In this kind of control, the controller can automatically adjust the hydraulic pump and the engine according to the change of the working condition, and the fuel consumption is minimized while ensuring that the output power meets the working needs.
9) Fieldbus technology and embedded systems will be widely used
As the degree of "intelligence" of hydraulic excavators increases, various sensors and controllers will spread throughout the excavator, which will cause the interior of the excavator to be filled with various wires and joints, which complicates the control system and reduces reliability. The solution to this problem is to use a fieldbus to connect all the sensors, controllers and actuators with a single serial line, while ensuring the system's powerful features, while having a simple structure and high reliability. At present, in the field of mobile machinery, there is such a field bus, called CAN bus, but it has not been widely used on excavators. The development of electronic technology makes the control chip smaller and more powerful. It has almost no space on the excavator and can be completely embedded in various parts. This is also the development direction of the excavator control system in the future.
The outer Spherical Ball Bearing is what we usually call the outer Spherical Bearing. The reason why it is called ball bearing is that it belongs to Deep Groove Ball Bearing, and the rolling element in it is steel ball.
Deep groove ball bearing outer spherical ball bearing is convenient to use the main characteristics of simple for loading and unloading, self-aligning ball bearings, standard tolerances for internal and external diameter reduction, adding tolerances to ensure the shaft with the light; each set of ball bearings are not alone to use and he must match to bearing inside the whole machine, the outer spherical bearing are of various shapes so the overall fit for various structural position after use. The ball bearing of the outer sphere can be divided into three categories according to the way of matching with the axis.
Outer spherical ball bearing with top wire
Its code is: UC200 series (light series), UC300 series (heavy duty Series), and deformation products UB (SB) 200 series. If the environmental load is small, UC200 series should be selected generally, otherwise UC300 series should be selected. Generally, there are two top threads on the outer spherical ball bearing, the angle between them is 120 degrees. The characteristic is that when the shaft fits with the shaft, the top wire is applied to the shaft to play a fixed role, but the environmental requirements for its matching must have a small vibration range. This kind of spherical ball bearing is widely used in textile machinery, ceramic machinery and other manufacturing industries.
Spherical spherical ball bearing with taper
Its name is: UK200 series, UK300 series. The inner diameter of the outer spherical ball bearing is the taper hole with a ratio of 1:12. When used, it must be combined with the tight sleeve. The characteristics of this kind of outer spherical bearing are: it can bear more load than the outer ball bearing with top wire. Because the diameter matched with the locking set the same model than with the top wire outer spherical ball bearing small, such as with the top wire outer spherical ball bearing UC209 inner diameter is 45mm, and is matched with the diameter of the shaft is 45mm, and if if change into a tapered outer spherical ball bearing, can only choose 45mm diameter sleeve, and 45mm adapter sleeve with taper outer spherical ball bearing is UK210 (of course, if the load is higher then you can choose the UK310). As a result, the load on UK210 is much larger than that of UC209.
Spherical spherical ball bearing with eccentric sleeve
Its name is: UEL200 series, UEL300 series, SA200 series. The main characteristic of this kind of spherical ball bearing is that there is a certain eccentricity on the upper end of the bearing, and the eccentric sleeve with the same eccentricity is cooperated with it. These bearings can also be said to be a special bearing, because it is mainly in agricultural machinery (harvester, straw machine, threshing machine etc.) on the use of this kind of outer spherical ball bearing is mainly used to beat hard structure, combined with the eccentric structure can effectively reduce the dynamic jump violently.
Double layer seal
The outer spherical ball bearings than other ordinary bearings is a double seal, because the outer spherical ball bearing the use of environmental conditions are harsh, especially agricultural bearing even more, and the double sealing to ensure the dust is not easy to enter the channel within the last two years, some companies developed the outer spherical bearing three lip seal the more greatly enhance dustproof ability, prolonging the service life of the bearing.
Spherical Bearing
Spherical Bearing,Small Spherical Bearing,Mini Spherical Bearing,Spherical Roller Thrust Bearing
LUOYANG AUTO BEARING CO.,LTD , http://www.lyautobearing.com