DE4225993C1 - Fuel vapour recovery system for automobile fuel tank - uses absorption element within storage chamber coupled to electromagnetically operated valve supplying fuel vapour to air intake. - Google Patents

Abstract

The fuel vapour recovery system allows fuel vapour in free spaces above a surface of the fuel in a vehicle fuel tank to be collected and closed to an air intake line (3) for the vehicle ic engine (4). A vent line (6) coupling the fuel tank space to the atmosphere (5) has a storage chamber (7) with an absorption element for collecting the vapourised fuel. The storage chamber is coupled to the air intake line via an electromagnetically operated valve (10). The valve has a single inlet (11) and 2 outlets (12.1, 12.2) each associated with a non-return valve and coupled to the air intake line on opposite sides of a turbocharger. The valve has 2 valve seats in series, respectively associated with the 2 outlets, the first valve seat having an electrically operated drive (20) coupled to a diagnosis block (21). ADVANTAGE - Reduced fuel flow resistance within valve and improved removal of fuel vapour from absorption element.

Description

The invention relates to a device for temporary storage and dosed feeding of the volatile in the free space of a tank system Fuel components in the intake pipe of an internal combustion engine, includes a ventilation line that connects the free space with the atmosphere device in which a storage chamber is arranged with an absorption element is, as well as at least one the storage chamber with the intake pipe end the line ver by an electromagnetically actuated valve is closable, the valve at least one inlet opening and at least has an outlet opening and wherein between the inlet and the outlet opening tion at least one valve seat is provided, the valve with respect to a use of the device in an internal combustion engine, the is chargeable by a charger, has two outlet openings, one the outlet openings flow-conducting with the low pressure area of the La ders and the other outlet opening flow-conducting with the intake pipe is connected, wherein the first suction opening, a first check valve is assigned, which can only be flowed through in the direction of the intake pipe and a second check valve being assigned to the other outlet opening which can only be flowed through in the direction of the charger.

Such a device is known from DE-PS 41 39 946. The one with the La the connected outlet opening and the second check valve and the outlet opening connected to the intake pipe and the first check Valve are downstream of the valve seat in the direction of flow. At the Switching off the internal combustion engine prevents fuel vapors casually kept away from the loader, as the electromagnetically operated  The valve is then in the "closed" position. The second check valve can work with low closing forces, which means that the Enable valve and thereby feed the fuel components at low differential pressures in the internal combustion engine. Here, al However, it should be noted that the flow resistances in charging mode ver are equally high and therefore the disposal of the absorption element is undesirably hindered in this load state.

The invention has for its object a generic contraption to evolve in such a way that in the loading mode of combustion Engine significantly reduced from the volatile fuel components flow resistances within the valve must be overcome sen and thereby improves the disposal from the absorption element becomes.

This object is achieved by the characterizing features of claim 1 ge solves.

The subclaims refer to advantageous refinements.

To solve the problem it is provided that with the loader connected outlet opening and the second check valve the valve seat upstream in the direction of flow and the connected to the intake pipe Outlet opening and the first check valve in the valve seat Flow direction are downstream. The advantage here is that in the drawer operation when high throughputs of regeneration air are unproblematic for the Mixture composition of the internal combustion engine are only slight Flow resistances from volatile fuel components within the device must be overcome. The way through the ver equally higher flow losses take valve seat volatile fuel components only in suction mode, where higher anyway Differential pressures are present across the valve.

A compressor is closed under a charger in the sense of the present invention understand, for example, by an exhaust gas turbocharger, a mecha  nisch driven spiral loader or a Roots blower can be formed. The construction of the device according to the invention is low in parts and very simple. A complex switching of the device between suction and loading Operation is unnecessary, ensuring reliable operation during a lan conditions of use of the device. Switching from suction on charging is done by those prevailing within the device Pressure conditions automatically. The control of the electromagnetic be Actuable valve is carried out via an electronic engine control, which at for example to control the injection systems anyway ge application reaches. Such a motor control can provide a variety of information Make available, which are used to control the valve can.

The valve according to the invention is characterized by smaller dimensions from what is particularly cramped for using the device Space is an advantage.

With regard to an improved fine dosing in the area close to idling Suction mode and a simultaneous high flow in suction mode Full load and partial load can give the valve seat an auxiliary valve seat in a row scarf device downstream, which can be closed by a vacuum adjuster is, the vacuum adjuster can be actuated by a differential pressure. With such a configuration, it is advantageous if the first outlet opening after the valve seat and the second outlet opening after the auxiliary valve seat is switched.

The advantage here is that in the loading mode, if the combustion is well filled is required, higher regeneration quantities can be achieved easily with the mixture can be fed. Flow losses in the area of the lower pressure adjuster can then be avoided.

In addition to a very good fine metering of the volatile fuel components in the intake pipe in the area close to idling during suction operation is without construction  Liche change of the device also in suction at partial and full a good flow through the device.

For better performance during a long ge the auxiliary valve seat can be used by a vacuum adjuster elastomeric material can be closed, which has a support collar, where in the support collar on the one hand on a bellows-shaped control membrane and on the other hand rests on a compression spring. Due to the bellows-like shape The design of the control diaphragm will reduce the service life tensions inside the membrane during intended use casually avoided. The vacuum adjuster requires a particularly sensitive one Regulating the mass flow through the device and avoiding it additional control elements.

With regard to a simple structure and a good economical manufacture availability, the check valves can be actuated by differential pressure. The check valves advantageously have sealing bodies which are not differential pressure applied condition under elastic preload automatically arranged in the area of the outlet openings Sealing seat can be brought into engagement and close the outlet openings. The Check valves can, for example, by Elastomerplatten-Federsy be formed steme or by elastically deformable tongue or plates valves made of polymer material. For better adjustment of the opening and The tongue or plate valves, for example, can have a closing characteristic a reinforcement made of an elastic, non-creeping material have of the elastically deformable, polymeric material is enclosed. Depending on the shape of the reinforcement and the spring characteristic can use the device with relative properties simple means to the respective circumstances of the application be adjusted.

The valve seat can be operated with an electrically operated and electrical Connections may be provided, the connections advantageously with egg  are connected to a diagnostic block. The advantage here is that a ver casual monitoring of the device can be done. The diagnostic block, the for example form part of a map of an engine control can control the loading depending on various input variables actuation of the valve and thus the volumetric flow of volatile fuel components in the intake pipe of the internal combustion engine depending of the respective load condition. The electromagnetically actuated valve can for example clocked and there are, depending on the Tastver keep different dosing quantities free. Under the duty cycle the Relationship between the period of the open valve to Ge total period, i.e. the period of the open and the closed its valve, understood. Diagnostics can be used to monitor the system block, for example, be connected to a control instrument. At About an arbitrarily defined threshold value, which is the difference Describes the setpoint and actual value of the mass flow that has been implemented visual and / or acoustic signals to the operator of the internal combustion engine Draw attention to the error.

The input signals of the diagnostic block can, for example, by the Position of the throttle valve, the speed of the internal combustion engine, ver different temperatures and pressures inside and outside the combustion tion engine and the exhaust gas composition be formed.

Additional input and output variables are also conceivable. Several out Examples of management of the device according to the invention are shown below explained in more detail with reference to the accompanying drawings. It shows:

Fig. 1 is an overall view in which the ge for use long end parts are shown in a schematic representation;

Fig. 2 shows a first embodiment of the Ven shown in Fig. 1 TILs

Fig. 3 shows a third embodiment, the valve having a bypass valve seat in addition to a valve seat,

Fig. 4 is a diagram in which the flow is plotted both in loading operation and in suction operation over the corresponding differential pressure and

Fig. 5 is a diagram in which the flow is plotted against the differential pressure during charging, the curves within the diagram showing the effects of the arrangement of the second check valve according to the invention in contrast to the valve from the prior art.

The device shown in Fig. 1 comprises an internal combustion engine 4 , which can be charged by a charger 16 . A throttle valve 22 , shown enlarged, is arranged within the intake pipe 3 . The air filter of the internal combustion engine 4 is hen with reference numeral 23 verses. The electromagnetically actuated valve 10 is shown only schematically in Fig. 1 and in its outer outline. It has two outlet openings 12.1 , 12.2 and an inlet opening 11 , which is connected via a line 9 to the absorption element 8 of the storage chamber 7 . The volatile fuel components from the free space 1 of the tank system 2 reach the storage chamber 7 via a ventilation line 6 and are absorbed by the absorption element 8 . Depending on the suction or charging mode of the internal combustion engine 4 , the volatile fuel components get from the free space 1 and the absorption element 8 through the line 9 into the valve 10 .

In suction mode, the volatile fuel components flow through the first outlet opening 12.1 and are sucked in by the negative pressure in the intake pipe 3 of the internal combustion engine 4 . In this case, the volatile fuel components are fed in in the flow direction behind the throttle valve 22 . In charging mode, when there is a relative positive pressure within the intake pipe 3 , the first check valve 17 closes the first outlet opening 12.1 and the volatile fuel components pass the second check valve 18 of the second outlet opening 12.2 in the direction of the charger 16 . The volatile fuel components as well as the fuel-air mixture are conveyed with excess pressure into the combustion chambers of the internal combustion engine 4 . The diagnostic block 21 and the display instrument 24 serve to monitor and control the device according to the invention. Depending on input variables, such as the position of the throttle valve 22 , the speed of the internal combustion engine 4 and / or the exhaust gas composition, the passage of volatile fuel components into the internal combustion engine 4 is regulated.

In Fig. 2, a first embodiment of the valve 10 from the Vorrich device according to FIG. 1 is shown enlarged as a single part in a section. The valve 10 has a drive 20 which is connected in a signal-conducting manner to a diagnostic block, not shown here. The drive 20 regulates the flow, depending on parameters entered in the diagnostic block. Inside one of the two outlet openings 12.1 , 12.2 , a check valve 17 , 18 is arranged, the check valves 17 , 18 in this embodiment and in the following valves being formed by elastically deformable tongues. These can, for example, as shown here, be substantially disc-shaped or have a lenticular cross-section. According to another embodiment, not shown here, commercially available spring-loaded elastomer plate check valves, for example, can also be used as valves. The outlet opening 12.2 connected to the charger 16 and the second check valve 18 are connected upstream of the valve seat 13 in the flow direction in this exemplary embodiment. Regardless of the position of the valve 10 , the volatile fuel components flow directly from the inlet opening 11 past the second check valve 18 into the outlet inlet opening 12.2 . The advantage here is that the volatile fuel constituents are only opposed by low flow resistances, so that high throughputs and thus operating point for this engine operating point can be realized without problems high regenerations.

In Fig. 3, a valve 10 is shown, the valve seat 13 downstream in a series circuit of an auxiliary valve seat 14. The auxiliary valve seat 14 can be closed by a vacuum actuator 15 , wherein the vacuum actuator 15 can be actuated by a differential pressure.

The auxiliary valve seat 14 is conical in this embodiment and, if necessary, can be brought into engagement with a conical closure member made of elastomer material.

The first outlet opening 12.1 is connected downstream of the auxiliary valve seat 14 .

For the function of the exemplary embodiments according to FIGS. 2 and 3, the following is carried out in connection with the diagram from FIG. 4:

Is shown in Fig. 4 as well as in Fig. 5, applied a diagram in which the ordinate represents the mass flow rate on the abscissa and the pressure difference Ap is plotted. At the intersection of the two axes, the flow as well as the differential pressure Δp is zero. Starting from the zero point of the abscissa to the right, the pressure differences of the negative pressure during suction operation are shown, while starting from the origin to the left, the positive pressure differences, i.e. overpressure during charging, are shown.

In the illustrations in Figs. 4 and 5 is schemati cal representations of the relationships between the respective extended refinements of the valves to make it clear. Numerical values cannot be derived from the representations.

The abscissa to the right of the intersection of the two axes is divided into three areas 25 , 26 , 27 , which symbolize the operating states of the internal combustion engine. Area 25 is the idle area, loading area 26 is the partial load area and area 27 is the full load area in suction mode. Area 28 , which is shown on the abscissa to the left of the ordinate, shows the operating behavior of the valves 10 during charging.

The characteristic curves of the valve 10 shown in FIG. 2 are designated by the reference numbers 29 , 30 and 31 . The characteristic curves of the valve from the prior art have the reference numbers 32 , 33 and 34 .

The operating behavior of the valve shown in Fig. 3, which in addition to the valve seat 13 also has a secondary valve seat 14 , is described by the characteristic lines 35 , 36 and 37 .

The valve 10 shown in FIG. 2 is to be used in an internal combustion engine 4 which is to be operated without disposal of the absorption element 8 during idling 25 , that is to say without idling regeneration. Due to the design of the valve 10 , which was designed with regard to a maximum throughput both at full load 27 in suction and in loading mode 28 , the characteristic curve 29 results when the valve set 13 is completely open. In Fig. 4 it can be seen that the mass flow is higher at the same pressure difference Δp than in the valves 10 from the prior art and Fig. 3 (characteristic curves 32 and 35 ). To reduce the flow through the valve 10 , this can be controlled clocked, so as to close and open the valve seat 13 as needed. The comparatively large opening cross-section, which operated in Vollastbe 27 , 28 requires a high flow rate, on the other hand requires a relatively high flow rate (characteristic curve 30 ) through the valve 10 , so that it becomes a, in idle 25 and in the transition region from idle 25 to part load 26 Overfatting of the internal combustion engine can occur when volatile fuel components are fed into the area close to idling. Therefore, no idle regeneration is dispensed with in such a design and objective.

At idle 25 of the internal combustion engine 4 , the auxiliary valve seat 14 of the valve 10 according to FIG. 3 is almost closed by the vacuum adjuster 15 in order to limit the flow of volatile fuel components in the area between the throttle valve 22 and the internal combustion engine 4 . Under partial load 26, the feed of volatile fuel constituents is controlled in the intake pipe 3 through the vacuum actuator 15, the vacuum actuator 15 by ei be NEN differential pressure between the atmosphere and the interior of the valve 10 is tätigbar. In charging mode 28 , when the maximum possible supply of volatile fuel components from the absorption element 8 into the internal combustion engine 4 is required and excess pressure is present in the intake duct 3 , the first check valve 17 of the first outlet opening 12.1 closes automatically due to the pressure difference, so that a short circuit through the valve 10 is reliably avoided. In this case, the second outlet opening 12.2 is open and the volatile fuel components and the fuel / air mixture are conveyed into the combustion chambers of the internal combustion engine 4 with overpressure. The valve seat 13 is provided with an electrically actuable drive 20 , the drive 20 preferably being connected in a signal-conducting manner to a diagnostic block as shown in FIG. 1. The diagnostic block has signal inputs and signal outputs that are required for monitoring the proper functioning of the device. The input data can be formed, for example, by characteristic values which are available in any case for electronic engine management that is used. Irregularities within the device are displayed on a display instrument 24 in order to monitor the device when an arbitrarily defined threshold value, which describes the tolerance between the actual value and the desired value, is exceeded. By connecting valve seat 13 and auxiliary valve seat 14 , the characteristic curve provided with reference number 35 from FIG. 4 is established. Such a valve 10 can on the one hand ensure a sufficiently low flow rate to be able to feed the volatile fuel components even when idling without the risk of over-greasing in the internal combustion engine 4 and on the other hand provides a sufficiently large flow rate in suction operation during the partial load 26 and full load range 27 to disposal.

The valve 10 shown in Fig. 2 is characterized by a particularly compact design and by the use of a few individual parts, which is particularly economical in economic terms.

In the left part of the illustration of FIG. 4, the charging operation 28 is shown, since in this area the maximum passage cross section through the valve 10 is dimensional, a result is obtained which tends to correspond to the flow in the full load region 27 of the suction operation. The valve shown in Fig. 3 has the relatively largest flow (characteristic curve 31 ). The valve shown in FIG. 4 has a medium flow (characteristic curve 36 ) in charging mode 28 , while the valve shown in FIG. 3 has a comparatively lower flow rate (characteristic curve 34 ).

In FIG. 5, reference is made to the configuration of the valves according to FIG. 2 and the prior art.

Due to the particularly low flow resistance through the valve 10 from FIG. 2, a flow, which is represented by characteristic curve 37 , results in the charging mode 28 as a function of the excess pressure.

The comparatively higher flow resistances, which are opposed to the volatile fuel components within the valve 10 from the prior art, on the other hand reduce the flow compared to the flow through the valve from FIG. 2. The characteristic curve for the valve 10 shown in FIG. 3, in which the volatile fuel components must also flow through the valve seat 13 in the charging mode 28 , is represented by characteristic curve 38 .

The device according to the invention is characterized by a simple structure, few individual parts and economical manufacturability. It is also from added importance that with a slight change in the construction Usage properties can be achieved, which adapt particularly well to the respective Have the circumstances of the application adapted.

Claims (8)

1.Device for the temporary storage and metered feeding of the volatile fuel components located in the free space of a tank system into the intake pipe of an internal combustion engine, comprising a vent connecting the free space with the atmosphere, in which a storage chamber is arranged with an absorption element, and at least one the storage chamber with the intake pipe connecting line, which can be closed by an electromagnetically actuated valve, the valve having at least one inlet opening and at least one outlet opening and wherein at least one valve seat is provided between the inlet and the outlet opening, the valve with respect to use of the device in an internal combustion engine, which is chargeable by a charger, has two outlet openings, one of the outlet openings flow-conducting with the low-pressure region of the charger and the other outlet opening is conductively connected to the intake pipe, the first suction opening being assigned to a first check valve which can only be flowed through in the direction of the suction pipe and the other outlet opening being assigned a second check valve which can only be flowed through in the direction of the charger, characterized in that the outlet opening ( 12.2 ) connected to the loader ( 16 ) and the second check valve ( 18 ) upstream of the valve seat ( 13 ) in the direction of flow and the outlet opening ( 12.1 ) connected to the intake pipe ( 3 ) and the first check valve ( 17 ) to the valve seat ( 13 ) are connected downstream in the flow direction. 2. Device according to claim 1, characterized in that the Ven valve seat ( 13 ) has an auxiliary valve seat ( 14 ) connected in series, that the auxiliary valve seat ( 14 ) can be closed by a vacuum adjuster ( 15 ) and that the vacuum adjuster ( 15 ) can be actuated by a differential pressure. 3. Apparatus according to claim 2, characterized in that the first outlet opening ( 12.1 ) the valve seat ( 13 ) and the second outlet opening ( 12.2 ) is connected downstream of the auxiliary valve seat ( 14 ). 4. Device according to one of claims 2 and 3, characterized in that the auxiliary valve seat ( 14 ) by a vacuum adjuster ( 15 ) made of elastomeric material is closable and that the vacuum adjuster ( 15 ) has a support collar which on the one hand on a bellows-shaped control membrane and on the other hand rests on a compression spring ( 19 ). 5. Device according to one of claims 2 to 4, characterized in that the vacuum adjuster ( 15 ) is effective against the spring force of a pressure spring ( 19 ) arranged in the valve ( 10 ). 6. Device according to one of claims 1 to 5, characterized in that the check valves ( 17 , 18 ) can be actuated by differential pressure. 7. The device according to claim 6, characterized in that the return check valves ( 17 , 18 ) have sealing bodies which in the non-differential pressure state under elastic preload automatically with one in the region of the outlet openings ( 12.1 , 1 2.2) arranged sealing seat in engagement can be brought and close the outlet openings ( 12.1 , 12.2 ). 8. Device according to one of claims 1 to 7, characterized in that the valve seat ( 13 ) is provided with an electrically actuable drive ( 20 ), that the drive ( 20 ) is provided with electrical connections and that the connections conduct a signal with a diagnostic block ( 21 ) are connected.