Method and device for detecting fault of high-pressure oil pump incapable of establishing low rail pressure

Abstract

The invention discloses a method and a device for detecting a fault of a high-pressure oil pump incapable of establishing a low rail pressure. The method comprises the following steps: when a controlled practical fuel oil flow flowing into the high-pressure oil pump is the minimum flow, detecting a first practical rail pressure of a common-rail pipe; if the first practical rail pressure is constantly higher than a preset rail pressure and a theoretical oil supply volume is less than or equal to a minimum threshold value, detecting a practical current of an oil volume metering unit; if a difference value between the practical current and a preset current is out of a preset range, confirming a driving circuit or wire harness fault of the oil volume metering unit; if the difference value between the practical current and the preset current is within the preset range, controlling the oil volume metering unit so as to set duty cycle and operate, detecting a second practical rail pressure of the common-rail pipe, and setting the duty cycle as the maximum duty cycle adding a preset offset; if the range amplitude of the second practical rail pressure is not less than the preset threshold value, confirming the oil volume metering unit being in characteristic drifting fault; and if the range amplitude of the second practical rail pressure is less than the preset threshold value, confirming the high-pressure oil pump being in mechanical fault.

Description

technical field [0001] The invention relates to the technical field of detection, in particular to a fault detection method and device for a high-pressure oil pump unable to establish a low rail pressure. Background technique [0002] see figure 1 The schematic diagram of the high-pressure common-rail system is shown. The high-pressure common-rail system mainly includes: high-pressure oil pump, common-rail pipe, pressure limiting valve and fuel injector, etc. Its working principle is as follows. It is provided to the high-pressure oil pump for pressurization. When the fuel is pressurized to the required pressure, it is sent to the common rail pipe; the common rail pipe has two oil inlet joints, and the oil inlet joints are connected to the high-pressure oil pump through two high-pressure oil pipes. The high-pressure oil pump adopts a double-piston pump structure, and the two plunger pumps alternately supply oil to the common rail pipe according to certain rules. There are a...

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Problems solved by technology

[0004] In the prior art, when low rail pressure needs to be established and the figure 2 In the double-closed-loop rail pressure control system shown, if it is detected that the actual rail pressure is continuously greater than the set rail pressure, then determine whether the theoretical fuel supply into the high-pressure oil pump in the double-closed-loop rail pressure control system is less than or equal to the minimum value, if less than or equal, then this detection method can only confirm that the high-pressure oil pump cannot establish the low rail pressure, but cannot determine the cause of the fault that the low rail pressure cannot be established in this case

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