VOLVO工程機械用柴油發(fā)動機電子控制技術

由于柴油機具備高扭矩、高壽命、低油耗、低排放等特點 ,柴油機成為解決汽車及工程機械能源問題最現實和最可靠的手段。因此柴油機的使用范圍越來越廣 ,數量越來越多。同時對柴油機的動力性能、經濟性能、控制廢氣排放和噪聲污染的要求也越來越高。依靠傳統(tǒng)的機械控制噴油系統(tǒng)已無法滿足上述要求 ,也難以實現噴油量、噴油壓力和噴射正時完全按最佳工況運轉的要求。近年來 ,隨著計算機技術、傳感器技術及信息技術的迅速發(fā)展 ,使電子產品的可靠性、成本、體積等各方面都能滿足柴油機進行電子控制的要求 ,并且電子控制燃油噴射很容易實現。

1：沃爾沃柴油機電子控制技術的要求

1.1沃爾沃柴油機高的噴射壓力

為滿足排放法規(guī)的要求 ,柴油噴射壓力從 10MPa提高到 200MPa。如此高的噴射壓力可明顯改善柴油和空氣的混合質量 ,縮短著火延遲期 ,使燃燒更迅速、更徹底 ,并且控制燃燒溫度,從而降低廢氣排放。

1.2沃爾沃柴油機獨立的噴射壓力控制

1.3改善沃爾沃柴油機燃油經濟性

用戶對柴油機的燃油消耗率非常關注。高噴射壓力、獨立的噴射壓力控制、小噴孔、高平均噴油壓力等措施都能降低燃油消耗率 ,從而提高了柴油機的燃油使用經濟性。

1.4沃爾沃柴油機獨立的燃油噴射正時控制

噴射正時直接影響到柴油機活塞上止點前噴入汽缸的油量,決定著汽缸的峰值爆發(fā)壓力和最高溫度。高的汽缸壓力和溫度可以改善燃油使用經濟性 ,但導致 NOX增加。而不依賴于轉速和負荷的噴射正時控制能力 ,是在燃油消耗率和排放之間實現最佳平衡的關鍵措施。

1.5沃爾沃柴油機可變的預噴射控制能力

預噴射可以降低顆粒排放 ,又不增加 NOX排放 ,還可改善柴油機冷啟動性能、降低冷態(tài)工況下白煙的排放 ,降低噪聲 ,改

善低速扭矩。但是預噴射量、預噴射與主噴射之間的時間間隔在不同工況下的要求是不一樣的。因此 ,具有可變的預噴射控制能力對柴油機的性能和排放十分有利。

1.6沃爾沃柴油機最小油量的控制能力

供油系統(tǒng)具有高噴射壓力的能力與柴油機怠速所需要的小油量控制能力發(fā)生矛盾。當供油系統(tǒng)具有預噴射能力后將會使控制小油量的能力進一步降低。由于工程機械用柴油機的工況很復雜 ,怠速工況經常出現 ,而電噴柴油機容易實現最小油量控制。

1.7沃爾沃柴油機快速斷油能力

噴射結束時必須快速斷油 ,如果不能快速斷油 ,在低壓力下噴射的柴油就會因燃燒不充分而冒黑煙 ,增加 HC排放。電噴柴油機噴油器上采用的高速電磁開關閥很容易實現快速斷油。

1.8降低驅動扭矩沖擊載荷

燃油噴射系統(tǒng)在很高的壓力下工作 ,既增加了驅動系統(tǒng)所需要的平均扭矩 ,也加大了沖擊載荷。燃油噴射系統(tǒng)對驅動系統(tǒng)平穩(wěn)加載和卸載的能力 ,是一種衡量噴射系統(tǒng)的標準。而電噴柴油機技術中的高壓共軌技術則大大降低了驅動扭矩沖擊載荷。

2：VOLVO沃爾沃柴油機組成

VOLVO工程機械用柴油發(fā)動機電子控制系統(tǒng)組成

傳感器、電控單元、執(zhí)行器。傳感器是用來監(jiān)控發(fā)動機上各部件及各系統(tǒng)的運行狀況 ,并將數據傳輸給 ECU。

( 1)增壓壓力與溫度 ;根據檢測到進氣壓力與溫度計算進氣量為 ECU提供計算噴油量的數據。

( 2)燃油溫度 :燃油溫度的升高會影響發(fā)動機性能 ,溫度高會降低柴油黏度 ,增加泄漏量需要加大供油量。

( 3)冷卻液溫度 :檢測發(fā)動機溫度提供為 ECU噴油正時修正的數據 ,并且為駕駛員提供發(fā)動機運行狀況。

( 4)冷卻液液位 :監(jiān)測水箱水位變化。

( 5)發(fā)動機凸輪軸速度 :為 ECU提供點火正時信號。

( 6)發(fā)動機曲軸速度 :也稱為發(fā)動機轉速傳感器 ,提供發(fā)動機轉速信號。

( 7)機油壓力 :監(jiān)測發(fā)動機潤滑系統(tǒng)運行狀況 ,為駕駛員提供發(fā)動機信息。

執(zhí)行器根據電控單元所傳輸過來的電壓信號來控制噴油正時與噴油量 ,在外部環(huán)境變化的情況下 ,E-ECU通過一系列傳感器采集到的信息 ,經過計算對比分析 ,然后通過對噴油器電磁閥 其工作原理為 :發(fā)動機凸輪作用于單體泵挺桿 ,ECU將收集通電時間的長短和早晚來調整噴油量與噴油正時。 VOLVO工程的傳感器信號分析處理后發(fā)出指令。使高速電磁鐵控制閥閉合、機械用柴油發(fā)動機的執(zhí)行器主要是有電磁閥的單體泵。結構和開啟 ,在單體泵內形成高壓 ,通過噴油器定時、定量將最佳霧化驅動方式。

其工作過程為 :當某缸需要噴油時 ,ECU向電磁閥提供 3.7V的電壓 (注:當起動時電壓可達 90V左右普通萬用表無法測量 ),使電磁閥移動將進油道堵死使內部形成密閉空間 ,此時柱塞在凸輪軸的推動下向上移動 ,建立油壓直至達到 220kg將噴油器打開向汽缸內噴射經霧化的燃油 ,工作完成。

另外 ,VOLVO工程機械用電控柴油機還包括對廢氣再循環(huán)閥、預熱塞等執(zhí)行機構進行控制 ,使柴油機運行狀態(tài)達到最佳。

VOLVO engineering machinery diesel engine electronic control technology
As the characteristics of the diesel engine with high torque, high life expectancy, low fuel consumption, low emissions, the diesel engine automotive and construction machinery, energy issues are the most realistic and the most reliable means. Therefore, the use of diesel engines range more widely, more and more quantity. Diesel power performance, economic performance, control emissions and noise pollution are increasingly high requirements. Rely on traditional mechanical control fuel injection system has been unable to meet the above requirements, it is difficult to achieve the fuel injection quantity, injection pressure and injection timing requirements fully functioning best conditions. In recent years, with the rapid development of computer technology, sensor technology and information technology, reliability, cost, size, and other aspects of the electronic products can meet diesel requirements for electronic control, electronically controlled fuel injection and are easy to implement.
 
1: Volvo diesel engine electronic control technology requirements
1.1 Volvo diesel engine high injection pressure
To meet emission regulations, diesel fuel injection pressure increased from 10MPa to 200MPa. Such a high injection pressure can be significantly improved the mix quality of the diesel fuel and air, to shorten the ignition delay period, so that combustion is more rapid, more thorough, and controlling the combustion temperature, thereby reducing exhaust emissions.
1.2 Volvo diesel engine independent injection pressure control
1.3 improve Volvo diesel engine fuel economy
The user is very concerned about the fuel consumption of the diesel engine. The high injection pressure, independent of the injection pressure control, small spray holes, high average Injection Pressure and other measures can reduce the fuel consumption rate, thereby improving the economy of the use of diesel fuel.
1.4 Volvo independent diesel engine fuel injection timing control
Injection timing directly affect the amount of oil sprayed into the cylinder of the diesel engine piston top dead point before, determines the peak cylinder pressure and the maximum temperature. The high cylinder pressure and temperature can improve fuel economy, but the NOX increase. Rather than rely on speed and load injection timing control capability is the key measures to achieve the best balance between the rate of fuel consumption and emissions.
The 1.5 Volvo diesel Variable pre-injection control capability
Pre-injection can reduce particulate emissions, without increasing NOX emissions, but also to improve the diesel engine cold start performance, reduce cold conditions white smoke emissions, reduce noise, change
Good low-speed torque. However, the interval between the pre-injection amount, the pre-injection and main injection is not the same in different conditions requirements. Therefore, having a variable pre-injection control capability of the diesel engine performance and emissions are very favorable.
1.6 Volvo diesel engine control capability of the minimum amount of oil
The small amount of oil needed by the fuel supply system with a high injection pressure diesel engine idling control capabilities in contradiction. Further reduce the ability to make the control of a small amount of oil when the oil supply system will have the ability to pre-injection. Idling condition is often very complex construction machinery diesel engine conditions, EFI diesel engine is easy to achieve a minimum fuel control.
1.7 Volvo diesel engine is quick off the oil capacity
Injection end must be fast off oil, and can not quickly off the oil, is injected at a low pressure of the diesel will be due to inadequate combustion smoky, increase in HC emissions. EFI diesel injector using high-speed solenoid switch valve is very easy to implement quick off the oil.
1.8 lower drive torque impact load
The fuel injection system working in a high pressure, both to increase the average torque of the drive system, and also to increase the impact load. Fuel injection system for smooth drive system's ability to load and unload, is a measure of the standard of the injection system. EFI diesel technology in high-pressure common rail technology greatly reduces the impact load of the drive torque.
2: VOLVO Volvo diesel engine composition
VOLVO engineering machinery diesel engine electronic control system components
 
Sensors, electronic control units, actuators. The sensor is used to monitor the operating conditions of the engine components and systems, and data transmission to the ECU.
(1) The supercharging pressure and temperature; intake air amount calculated according to the detected intake air pressure and temperature, the ECU provides the data of the calculated fuel injection quantity.
(2) Fuel temperature: the fuel temperature rise will affect the engine performance, the high temperature will reduce the viscosity of diesel to increase the amount of leakage need to increase the amount of oil.
(3) The coolant temperature: detection engine temperature ECU fuel injection timing correction of data, and provide the driver with the engine operating conditions.
(4) The coolant level: monitoring the tank water level changes.
(5) Engine the camshaft speed: for the ECU to provide an ignition timing signal.
(6) the engine crankshaft speed: also referred to as the engine speed sensor, the engine speed signal.
(7) Oil pressure: monitoring engine lubrication system operating conditions, for the driver to provide engine information.
 
The actuator according to the transmission over the voltage signal by the electronic control unit to control injector timing and fuel injection quantity in the case of the external environment changes, E-ECU collected by a series of sensors to the information, after calculation of comparative analysis, and then through injector solenoid valve works: the engine cam acting on single pump tappet ECU will collect the energized length of time, and sooner or later to adjust the fuel injection quantity and injection timing. VOLVO engineering sensor signal analysis and processing to give instructions. High-speed solenoid control valve is closed, the machinery diesel engine actuator solenoid valve single pump. Structure and open, in a high-pressure unit pump, injector timing, the best atomization driven quantitative way.
 
The course of their work: when a cylinder needs fuel injection ECU to the solenoid valve 3.7V voltage (Note: When starting voltage up to 90V so ordinary multimeter can not measure), the solenoid valve moving Inlet Road blocked so formed inside the confined space, the plunger moves upward in the camshaft driven the establishment of hydraulic until it reaches 220kg open the injector jet by the atomization of fuel into the cylinder, the work is completed.
VOLVO Construction Machinery Diesel Engine and also includes exhaust gas recirculation valves, glow plugs and other implementing agencies to control the engine running state to achieve the best.