US 8,127,596 B2 · Method for verifying the tightness of a tank bleeding system without using a pressure sensor

Abstract

In a method for verifying the tightness of a tank bleeding system with a tank bleeding valve, a stop valve for air-tightly closing the tank bleeding system relative to an atmosphere prevailing outside the motor vehicle, and a bistable pressure switch whose switched condition indicates whether a predefined switching pressure is exceeded or not reached in the tank bleeding system, in order to be able to determine the tightness of the tank bleeding system without using a pressure sensor, the following steps are carried out: waiting until the vehicle speed drops below a certain threshold; opening the tank bleeding valve; closing the tank bleeding valve when a negative pressure has been attained which lies below the switching pressure; measuring the duration from the time an initial pressure lies below the switching pressure until the moment the switching pressure is exceeded again; and assessing the tightness is assessed based on the measured duration.

Claims20

Dependent claims

A method for verifying the tightness of a tank venting system of a motor vehicle, wherein the tank venting system comprises:

a tank venting valve in a regeneration line, which connects a storage container collecting fuel vapor from a fuel tank to an intake pipe of an internal combustion engine,
a stop valve for sealing the tank venting system so that it is air-tight against an atmosphere prevailing outside the vehicle and
a bistable pressure switch, the switching states of which indicate that the pressure in the tank venting system is above or below a predetermined switching pressure, the method comprising the steps:
waiting for the vehicle speed to drop below a threshold,
opening the tank venting valve,
controlling the stop valve such that the pressure in the tank venting system alternates from above the switching pressure to below the switching pressure, thereby toggling the bistable pressure switch,
closing the tank venting valve when a negative pressure has been attained that is below the switching pressure,
measuring the period from an initial pressure that is below the switching pressure until the next time the pressure exceeds the switching pressure,
assessing the tightness using the measured duration.

6 more elements

A system for verifying the tightness of a tank venting system of a motor vehicle, comprising:

a tank venting valve in a regeneration line, which connects a storage container collecting fuel vapor from a fuel tank to an intake pipe of an internal combustion engine,
a stop valve for sealing the tank venting system so that it is air-tight against an atmosphere prevailing outside the vehicle and
a bistable pressure switch, the switching states of which indicate that the pressure in the tank venting system is above or below a predetermined switching pressure,
wherein the system is operable to
wait for the vehicle speed to drop below a threshold,
open the tank venting valve,
control the stop valve such that the pressure in the tank venting system alternates from above the switching pressure to below the switching pressure, thereby toggling the bistable pressure switch,
close the tank venting valve when a negative pressure has been attained that is below the switching pressure,
measure the period from an initial pressure that is below the switching pressure until the next time the pressure exceeds the switching pressure, and to
assess the tightness using the measured duration.

7 more elements

Dependencies are inferred from the claim text.

Method for verifying the tightness of a tank bleeding system without using a pressure sensor

Life of this patent

Method for verifying the tightness of a tank bleeding system without using a pressure sensor

Life of this patent

Abstract

Claims20