Throttle valve installation and maintenance should pay attention to the following matters: The valve often requires operation, it should be installed in a convenient and convenient location.
When installing, pay attention to the direction of the media and the direction of the arrow marked by the valve body.
First, the source of throttle body deposits is relatively complex, but can be summarized as the following categories:
1. Mechanical contaminants in the oil, or colloids, asphalt, carbon slag, and other contaminants deposited by oxidation accumulate at the throttling gap.
2. Due to the aging of the oil or the extrusion of charged polarized molecules, there is a potential difference on the metal surface of the throttling gap, so the polarized molecules are adsorbed to the surface of the gap, forming a strong boundary adsorption layer, the thickness of the adsorption layer It is generally 5 to 8 microns, which affects the size of the throttle gap. When the above deposits and adsorbates grow to a certain thickness, they will be washed away by the liquid flow and then reattached to the valve port. In this way, the pulsation of traffic is formed.
3, valve port pressure is greater, due to the valve port temperature is high, the liquid squeezed to enhance the degree of metal surface is also more susceptible to friction and the formation of potential difference, so the pressure is large, easy to produce blocking phenomenon.
4. PCV exhaust gas source: The combustible mixture in the combustion chamber enters the crankcase through the gap between the pistons and is mixed with oil vapor to form a mixed gas. To avoid diluting and contaminating the oil, the mixture is drawn into the intake passage by a positive crankcase ventilation system (PCV) for secondary combustion. After this part of the exhaust gas enters the intake port, it will condense to form a liquid phase state due to a decrease in temperature, and the “unstable component” therein will oxidatively condense at a high temperature to form grease deposits on the surface of the throttle valve.
5. Lubricating oil of turbocharged compressors: For turbocharged engines, the exhaust gas driving method is widely used at present, that is, the high-pressure exhaust gas generated by the exhaust passage drives the turbine, and the compressed air vanes in the intake port are driven by the coaxial shaft. The formation of the inlet air flow pressurization. However, under long-term and harsh working conditions, coaxial bearings are prone to oil penetration and volatilization, and the addition of aeration efficiency increases exponentially, making it easier to form heavy oil stains to increase the adhesion of throttle body deposits.
6. Fuel steam discharged from the canister: In the fuel steam absorbed by the engine canister, it is easy to form the throttle deposit as long as it is cyclopentadiene, which can be oxidized and condensed to form colloidal grease at a constant high temperature.
Second, throttle valve maintenance and cleaning
When the throttle valve (ie, the butterfly valve) is obstructed by deposits, the value of the throttle opening value is disordered, the engine cannot stably and precisely control its opening, and the opening value is too low to cause start-up difficulties, unstable idling, or abnormal flameout. When the engine accelerates or decelerates, the throttle valve cannot respond in time and it will cause acceleration delay or sudden speed increase.