A method and device for realizing alternating control of positive and negative pressure of fuel tank

Abstract

The invention discloses a device for generating alternating air positive and negative pressures with specified curves, which includes parallel positive pressure tanks and negative pressure tanks, one end of the positive pressure tank is connected with an air compressor, the other end is connected with a fuel tank sample, and the negative pressure tank is connected with a negative pressure tank. One end of the pressure tank is connected to the vacuum pump, and the other end is connected to the fuel tank sample; a first proportional valve is connected in series between the positive pressure tank and the air compressor, and a first servo throttle valve is connected in series between the positive pressure tank and the fuel tank sample; A second proportional valve is connected in series between the pressure tank and the vacuum pump, a second servo throttle valve is connected in series between the negative pressure tank and the fuel tank sample; a first pneumatic shut-off valve is connected in series between the positive pressure tank and the first proportional valve, and the positive There is a second pneumatic stop valve in series between the pressure tank and the first servo throttle valve, a third pneumatic stop valve in series between the negative pressure tank and the second proportional valve, and a series connection between the negative pressure tank and the second servo throttle valve. There is a fourth pneumatic shut-off valve. The invention has the advantages of simple structure and convenient use, and effectively realizes the fast switching between the positive and negative pressures of the fuel tank.

Description

technical field [0001] The invention relates to a device for generating positive and negative pressures, belonging to the technical field of fuel tank detection, in particular to a device and method for generating alternating air positive and negative pressures with specified curves. Background technique [0002] In order to ensure that the pressure inside the fuel tank is balanced with the atmospheric pressure during the normal working process of the automobile, when the fuel in the fuel tank is heated and expands or when refueling is added to the fuel tank, the oil level rises and the pressure in the fuel tank increases. When the external pressure reaches a certain level, the valve opens; when the fuel in the fuel tank is cooled and shrinks or the fuel is pumped outward, the oil level drops and the pressure in the fuel tank decreases. When the pressure is lower than the external pressure to a certain level, the valve should also open. The normal working state of the fuel ...

AI Technical Summary

Problems solved by technology

This device also has the problem that when the fuel tank sample is pressurized directly through the positive and negative pressure source through the proportional valve, due to the large capacity of the fuel tank, the power required at the moment of positive and negative pressure alternating is extremely large, while the power of the air compressor and vacuum pump is limited. , can not reach the pressure-boosting rate required by the test, so that the fast switching between the positive and negative pressure of the fuel tank cannot be realized

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