Fluent material handling – with receiver or receiver coacting mea – Dribble or reduced flow at end of cycle
Reexamination Certificate
2000-07-18
2001-09-18
Douglas, Steven O. (Department: 3751)
Fluent material handling, with receiver or receiver coacting mea
Dribble or reduced flow at end of cycle
C141S301000, C141S286000, C220S086200
Reexamination Certificate
active
06289947
ABSTRACT:
The invention relates to a fuel tank system, particularly for motor vehicles, and a method of controlling and monitoring the system. Tank system refers to a mobile or stationary tank, particularly a fuel tank for a vehicle, that can be filled and emptied.
In such tank systems for fuel or other volatile liquids, emissions of fuel or liquid vapors should usually be avoided. In tank systems for motor vehicles, emissions that arise during operation and during fueling are avoided through the connection of the gas area that is present above the liquid level in the container, and forms a variable equalizing volume as a function of the fullness level, to an adsorption filter, such as an active-charcoal filter via at least one vent conduit. Currently, tank systems that employ various sensors to monitor the fueling process are being used in increasing numbers. For example, U.S. Pat. No. 5,197,442 describes a tank system for a motor vehicle, in which a sensor determines the internal pressure of the tank, and the opening state of the vent line is controlled as a function of the internal tank pressure. It is also known to detect further parameters for controlling and monitoring the fueling process. For example, US Re35,054 describes a tank system for a motor vehicle, in which the fuel temperature and fullness level are detected in addition to the internal tank pressure. While the monitoring devices of the known container systems prevent excessive fuel vapors or fuel via the vent lines, they do not, however, satisfactorily take into consideration fueling via the filling tube or conduit itself, and the associated problems, such as the overflow of fuel via the fuel conduit due to excessive internal tank pressure, or overfilling.
It is the object of the invention to provide a tank system that is improved in this regard, as well as a method of monitoring and controlling the system.
With respect to the method, this object is accomplished by the features of claim
1
. Accordingly, a sensor detects the fuel flow entering the tank, which is used as a parameter for monitoring and controlling the tank system. This sensor can determine, for example, whether a gas nozzle or nozzle hose is shut off at a given fuel level in the fuel tank. Hence, the tank-monitoring system can detect a nozzle malfunction and initiate corresponding actions, for example, protecting the adsorption filter from being flooded with liquid fuel. Furthermore, the proposed sensor can be used to determine whether, for example, the operator is attempting to continue filling the tank with fuel after the nozzle has shut off, for example, to round off the liter number or the price of the fuel.
In a preferred variation of the method, in the presence of a fuel flow in the filling tube, the gas area of the tank is connected to the adsorption filter via an additional vent conduit. Normally, in the tank systems discussed here, operational ventilation is effected by a vent conduit having a smaller flow cross section. When the fuel tank is filled, significantly-larger quantities of gas must be supplied to the adsorption filter. This is assured by the connection of an additional vent conduit having a larger flow cross section. In the system known from U.S. Pat. No. 5,197,442, the additional vent line is enabled when the fuel door is open. The drawback of this system is that the fueling ventilation is also active when the fuel door has been inadvertently left open during normal operation. Furthermore, the criterion of “fuel door open or closed” can scarcely be utilized in further control and monitoring functions, for example those relating to fueling. This is not the case in the proposed method.
For example, in a further preferred variation of the method, when a first fuel level is attained, the flow of fuel into the tank is reduced. Because of a throttling or a brief, possibly repeated, closure of the filling conduit, the fuel rapidly climbs to the nozzle or is swirled up to it. Consequently, the nozzle is shut off. The operator is thus informed that the tank system has been filled to a first fullness level, or a nominal volume, or is basically “full.” The filling conduit is only throttled or completely closed for a predetermined time. Afterward, the fuel can flow into the tank when the filling conduit is open. The flow sensor informs the system whether the performed measure has actually led to the shutoff of the nozzle hose; in the event of a shutoff of the nozzle and after the fuel has flowed off from the filling conduit, the sensor generates a corresponding signal. The flow sensor thus provides the monitoring system with continuous acknowledgement of whether a measure aimed at shutting off the nozzle has been successful.
If a gas nozzle has not been shut off, due to a structural stipulation or because of a malfunction, or if the operator is continuing the fueling process to “top off” the tank, the risk exists that fuel will reach the adsorption filter by way of the vent line. To prevent this, in a further variation of the method, all of the connections between the tank and the adsorption filter are broken when a second, maximum fullness level is reached, and the flow opening of the filling conduit is closed. This prevents the adsorption filter from being flooded with fuel. Immediately after the filling conduit has been closed, fuel travels upward, which either shuts off the properly-functioning nozzle hose or, if this is not the case due to a malfunction, fuel flows out of the filling opening of the filling conduit. In the extreme case discussed here, it is advantageous if not only all of the connections to the adsorption filter, that is, including the operational ventilation, are broken, but the ventilation conduit that assures the service ventilation connects with the atmosphere. Additional fuel can then flow off by way of this connection.
A problem occurring in methods or tank systems of the aforementioned type is that, during fueling, the fuel-air mixture—referred to hereinafter as vent gas—can reach the outside by way of the filling conduit. In some systems, an elastic collar that tightly surrounds the nozzle hose of a gas nozzle inserted into the filling conduit prevents this from happening. In other systems, the annular gap between the outer circumference of the nozzle hose and the wall of the filling conduit is kept as small as possible. This seal, referred to as a “liquid seal,” operates according to the sucking jet pump principle. When fuel is pumped, a vacuum is created on the tank side of the annular gap, which effects an inward-oriented air current through the annular gap. The drawback of the permanent seal is that it prevents the exit of fuel in the above-described extreme situation. The drawback of the seal operating according to the vacuum or Venturi principle is that it only operates satisfactorily if fuel is pumped at a relatively-high flow rate. In a proposed variation of the method, the aforementioned annular gap between the nozzle hose and the edge of the filling conduit is sealed during the fueling phase, and is re-opened after fueling is completed, or when the first or second fullness level is attained. This assures a hermetic seal during fueling, even if fuel pumping is interrupted in the process, or if fuel is compelled to flow out in the event of overfilling. A suitable sensor is required for the latter situation.
With respect to the fuel tank system, the object is accomplished by the features of claim
10
. Accordingly, in a fuel tank having a filling tube and an adsorption filter that is connected to the gas area of the tank, a flow sensor is disposed in the filling tube, which detects the presence or absence of a fuel flow. The flow sensor can be configured to indicate the magnitude of the fuel flow. It can do this by using a baffle plate that projects into the flow cross section of the filling conduit and shifts its inclination more or less, depending on the magnitude of the impacting fuel flow. Preferably, however, a capacitive flow sensor is used, because the magnitude of the fuel flow need not necessarily be
Auernhammer Helmut
Conrad Thomas
Duermeier Ewald
Ediger Bertold
Heimbrodt Klaus J.
Daimler-Chrysler AG
Douglas Steven O.
Venable
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