EP1254311A1

EP1254311A1 - Fuel supply system for internal combustion engines allowing for an improved filling of the fuel line

Info

Publication number: EP1254311A1
Application number: EP01919120A
Authority: EP
Inventors: Peter Schueler; Thomas Droege
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2000-01-28
Filing date: 2001-01-26
Publication date: 2002-11-06
Anticipated expiration: 2021-01-26
Also published as: WO2001055582A1; US20030159681A1; EP1254311B1; DE10003748A1; JP4488156B2; US6997168B2; DE50111004D1; JP2003521617A; ES2272454T3

Abstract

The invention relates to a fuel supply system for internal combustion engines which comprises a fuel tank (1) and a baffle pot (5) disposed therein. The fuel supply system is further provided with a fuel pump (11) that drives one or more fluid entrainment pumps (13) via a supply line (21) each and that fills the baffle pot (5) with fuel from the fuel tank (1). A fuel line (7) hydraulically links the baffle pot (5) with the internal combustion engine. When the internal combustion engine is started, the fuel pump (11) delivers fuel to the fuel line (7), thereby improving the starting behavior of the internal combustion engine.

Description

Fuel supply system for internal combustion engines with improved filling of the fuel line

State of the art

The invention is based on one

Fuel supply system for internal combustion engines with a fuel tank and a baffle arranged therein and means for filling the baffle with fuel from the fuel tank and with a fuel line hydraulically connecting the baffle to the internal combustion engine.

Such fuel supply systems are known. The swirl pot has the task of ensuring that the fuel line which is in the

The fuel supply system sticks out as long as possible and does not draw in air. This is particularly important when the tank is almost empty and / or when the motor vehicle is exposed to high lateral accelerations, so that the content of the fuel tank is pushed aside. This effect is achieved in that the swirl pot has a relatively small footprint and a height corresponding approximately to the overall height of the fuel tank, so that for

Filling the swirl pot requires only a relatively small volume of fuel. This Fuel volume is conveyed into the swirl pot by one or more fuel pumps, which draw in at the low point or the low points of the fuel tank. In order to save costs, it is customary to provide an electric fuel pump in the swirl pot which drives one or more jet pumps arranged at the low point (s) of the fuel tank, the jet pumps delivering fuel into the swirl pot. This arrangement avoids having to provide an electric fuel pump at every low point in the fuel tank, which would be expensive and prone to failure.

In many internal combustion engines, the fuel is supplied via a fuel line which is in _. a fuel supply system. The fuel is fed through a fuel feed pump that is directly coupled to the internal combustion engine. This means that at low engine speeds, the delivery rate of the fuel delivery pump is very low. As a result, the fuel delivery pump does not draw fuel from the fuel supply system or only to a small extent, which has a disadvantageous effect on the starting behavior of the internal combustion engine. In addition, starter and starter battery are heavily loaded. This operating behavior is particularly problematic when the fuel tank has been run empty, when the motor vehicle is initially filled with fuel in the manufacturer's plant or at low outside temperatures when the performance of the starter battery is reduced.

The invention has for its object to provide a fuel supply system for internal combustion engines, which improves the starting behavior of the internal combustion engine even under unfavorable circumstances and thus to relieve the starter battery and of the starter.

This object is achieved according to the invention by a fuel supply system for internal combustion engines with a fuel tank and one arranged therein

Baffle, with means for filling the baffle with fuel from the fuel tank and with a fuel line hydraulically connecting the baffle to the internal combustion engine, the means for filling the baffle at least temporarily delivering fuel into the fuel line.

Advantages of the invention

This measure ensures that the supply to the internal combustion engine does not only depend on the delivery rate of the fuel delivery pump of the internal combustion engine, but also, in particular when the internal combustion engine is started, that the means for filling the swirl pot are also used to deliver fuel into the fuel line. This ensures that fuel reaches the internal combustion engine through the fuel line within a very short time and that its starting behavior is thus improved. The fact that essentially existing means of the fuel supply system are used means that the costs for this measure are very low, which is particularly important for large-series vehicles.

In addition to the invention, it is provided that a connecting line is provided between the means for filling the baffle and the fuel line, so that the fuel quantity fed by the means for filling the baffle is fed into the

Fuel line can take place regardless of location and thus an adaptation to the structural conditions is possible.

In a variant of the invention it is provided that a pressure-maintaining valve is present between the means for filling the swirl pot and the fuel line, so that the working pressure of the jet pumps is always guaranteed. This also ensures that the swirl pot is always filled with fuel from the fuel tank. In addition, the pressure control valve at least partially prevents the fuel line from running dry during idle times of the internal combustion engine.

In addition to the invention, it is provided that a throttle is present between the means for filling the swirl pot and the fuel line, so that a defined distribution of the fuel flow delivered by the fuel pump to the jet pumps and the fuel line is made possible.

In another advantageous embodiment of the invention, a throttle and a check valve are provided between the means for filling the swirl pot and the fuel line, so that, on the one hand, a defined distribution of the fuel flow conveyed by the fuel pump is possible and prevents the fuel line from running dry during idle times of the internal combustion engine becomes.

In a further variant of the invention it is provided that a 3/2-way valve is present between the means for filling the baffle and the fuel line, that the directional valve connects the means for filling the baffle with the fuel line in its first switching position and that the third / 2-way valve in its second switching position connects the means for filling the baffle with the jet pump or pumps, see above that, if necessary, the entire delivery capacity of the fuel pump is available for filling the fuel line, which brings about a further improvement in the starting behavior of the internal combustion engine. On the other hand, the total funding is

Fuel pump can also be used to fill the baffle.

In a further addition to the invention, it is provided that a 3/3 directional control valve is present between the means for filling the surge chamber and the fuel line, and that the 3/3 directional control valve connects the means for filling the surge chamber with the fuel line in its first switching position. that the 3/3 directional control valve connects the means for filling the baffle with the fuel line and the jet pump or pumps in its second switching position and that the 3/3 directional control valve connects the means for filling the baffle with the jet pump or pumps in its third switching position , In this embodiment, the rapid filling is the

Fuel line ensured by the fuel pump; on the other hand, the jet pumps in the fuel tank are also driven as soon as the second switching position is reached, so that a decrease in the fuel level in the surge pot is prevented.

In a further addition to the invention it is provided that the 2/3-way valve or the 3/3-way valve is spring-loaded into its first switching position and that the 2/3-way valve or the 3/3-way valve is against a spring force using Fuel is moved from the means for filling the surge pot into the second and, if necessary, third switching position. This arrangement ensures that after each shutdown of the internal combustion engine and thus also the fuel pump in the fuel supply system, the 2/3 way valve or the 3/3-way valve is brought into its first switching position so that the fuel line is filled immediately when the fuel pump begins to deliver. Due to the fact that the fuel pumped by the fuel pump actuates the directional control valves, depending on the pressure level of the fuel pumped by the fuel pump, the spring force and a possible throttle, they reach the second and possibly the third switching position after a certain time. This ensures that the jet pumps are driven by the fuel pump a short time after the start of fuel delivery and thus the surge pot is also filled.

In a further embodiment of the invention, it is provided that the fill level of the swirl pot is kept at least at the fill level of the tank independently of the means for filling the swirl pot, so that the fuel line and the fuel pump never suck in air and, on the other hand, continuous operation of the fuel pump can be avoided. As a result, the fuel pump can be designed for a shorter service life, which contributes to saving costs and reducing the need for drive energy for the fuel pump.

In a further addition to the invention, it is provided that the means for filling the baffle include an electric fuel pump, so that the means for filling the baffle are inexpensive and can be controlled easily.

In a further addition to the invention, it is provided that the fuel pump drives at least one jet pump arranged in the installation position in the vicinity of the low point (s) of the fuel tank and that the jet pump or the jet pumps fuel into the swirl pot promote so that all the fuel in the fuel tank is easily conveyed into the baffle.

In a further embodiment of the invention, the fuel line has a check valve, so that the fuel line is prevented from running dry while the internal combustion engine is at a standstill.

Further advantages and advantageous embodiments of the invention can be found in the following drawing, its description and the patent claims.

drawing

Show it:

1 shows a first exemplary embodiment of a fuel supply system according to the invention with a pressure holding valve;

2 shows a second exemplary embodiment of a fuel supply system according to the invention with a throttle;

3 shows a third exemplary embodiment of a fuel supply system according to the invention with a throttle and a check valve;

Fig. 4 shows a fourth embodiment of a fuel supply system according to the invention with a 3/3-way valve in a first switching position;

Fig. 5 shows the embodiment of FIG. 4 in a second switch position;

6 shows the exemplary embodiment according to FIG. 4 in a third switching position; and

7 shows the characteristic curves of the exemplary embodiments according to FIGS. 1 to 3.

Description of the embodiments

The same numbers are assigned to the components that match in the following figures, and what has been explained with reference to one figure applies accordingly to the other figures.

Fig. 1 shows a first embodiment of a fuel supply system according to the invention with a pressure maintaining valve in a schematic representation. A fuel tank 1, the upper half of which is not shown in FIG. 1, has two low points 3 in the installed position. A surge pot 5 is arranged in the fuel tank 1 and is open at the top.

The internal combustion engine, not shown, or the fuel feed pump belonging to it, delivers fuel from the surge pot 5 to the internal combustion engine through a fuel line 7 projecting into the surge pot 5. In order to prevent the fuel line 7 from running dry, a first check valve 9 is provided at its end.

The swirl pot 5 has the task of ensuring, even with a low fuel level in the fuel tank 1, that fuel and not air is drawn in through the fuel line 7 as long as possible. The surge pot 5 has a very large amount compared to the base of the tank 1 smaller footprint, and its wall has approximately the height of the fuel tank 1. This makes it possible to achieve a high level in the swirl pot 5 with a small amount of fuel and thus to ensure that the fuel line 7 draws fuel as long as possible.

The baffle 5 is filled with means for filling the baffle. These means essentially consist of a fuel pump 11 and one each

Jet pump 13 in each low point 3 of the fuel tank 1. One of the jet pumps 13 feeds fuel into the baffle 5 in the lower region thereof and has a second check valve 15, which prevents fuel from flowing back into the tank 1 from the baffle 5. When the fuel pump 11 is switched off, the surge pot 5 is filled via the check valve 15, as a result of which the fill level in the surge pot 5 is at least approximated to that in fuel 1. The other jet pump 13 delivers over the upper edge of the surge pot 5 into the latter, so that no check valve is required.

A fuel return 17 opens into the fuel tank 1 and discharges excess fuel into the fuel 1. The fuel pump 11 draws fuel from the swirl pot 5 via a prefilter 19 and conveys it via supply lines 21 to the jet pumps 13 and via a connecting line 23 into the fuel line 7. In order to ensure the pressure required for the jet pumps 13, there is in the connecting line 23 an overflow valve 25 is provided, which is dimensioned such that it only opens when the required working pressure of the jet pumps 13 has been reached. As soon as the overflow valve 25 is opened, part of the fuel delivered by the fuel pump 11 is passed through the Connection line 23 promoted in the fuel line 7. The first check valve 9 in the fuel line 7 also prevents the fuel from the connection line 23 from getting back into the swirl pot 5. This arrangement ensures that the fuel line 7 is filled with fuel within a very short time and thus enables the internal combustion engine to be started.

7 is the characteristic of this invention

Embodiment shown in a diagram. The pressure difference is plotted in bar on the abscissa 27, while the ordinate 29 indicates the flow rate in liters per hour. The characteristic curve of the first exemplary embodiment is provided with the marking 31. The result of this is that the overflow valve 25 opens only when a pressure difference of 0.3 bar is reached, and the flow, beginning at zero, increases linearly with increasing pressure difference.

FIG. 2 shows a second exemplary embodiment of a fuel supply system according to the invention, which has a throttle 33 in the connecting line 23 instead of a pressure holding valve. This results in a changed characteristic curve compared to the first embodiment. 7 shows the characteristic curves 35 and 37 for two different throttle cross sections. It follows from this that even with a very small pressure difference, fuel is already conveyed into the connecting line 27, so that the fuel line 7 is filled more quickly. Under unfavorable circumstances, the pressure which arises on the pressure side of the fuel pump 11 may be too low to ensure the function of the jet pumps 13.

To prevent this, in one embodiment 3, a throttle 33 combined with a third check valve 39. 7 shows the characteristic curve 41 of the check valve 39. It can be seen from this illustration that when a certain pressure difference, here about 0.16 bar, is reached, the third check valve 39 opens and the flow increases very sharply with an increasing pressure difference. The combination of the characteristic curves of the third check valve 39 and the throttle 33 is shown in FIG. 7 as a characteristic curve 43. From this characteristic curve it follows that in this exemplary embodiment a certain pressure difference is built up before fuel is delivered from the feed pump 11 into the fuel line 7. This improves the working conditions for the jet pumps 13, and the third check valve 39 also ensures that when the internal combustion engine is at a standstill, no fuel flows back from the fuel line 7 into the surge pot 5 via the connecting line 23. This ensures that the fuel line 7 cannot run empty when the internal combustion engine is at a standstill. This also contributes to the improved starting behavior of the internal combustion engine.

It goes without saying that the characteristic curves 31, 35, 37, 41 and 43 from FIG. 7 are only exemplary for a specific combination of fuel pump 11, connecting line 23, overflow valve 25, throttle 33 and / or check valve 39. By changing individual or several of the components mentioned, the quantitative course of the characteristics mentioned can be varied within wide limits; however, the qualitative course of the characteristic curves is retained.

4, 5 and 6, a fourth embodiment is shown in different operating states. The fuel line 7 has a fuel filter 45 and a fuel feed pump 47. The control of the by The fuel pump 11 of fuel delivered from the surge pot 5 is carried out by a 3/3-way valve 49, which is shown in a first switching position. The 3/3-way valve 49 has a first connection 51, which connects the fuel pump 11 to the 3/3-way valve 49. A second connection of the 3/3-way valve 49 is connected to the connecting line 23, while the third connection is connected to the supply line 21.

The 3/3-way valve has a piston 53. This piston 53 has a connecting bore with throttle 55, which connects a first space 57 of the 3/3-way valve 49 with a second space 59. A spring 63 is arranged in a third space 61, which always brings the 3/3 directional control valve into the first switching position shown in FIG. 4 when the fuel pump 11 is out of operation.

As soon as the fuel pump 11 is put into operation, it pumps into the first space 57 of the 3/3 directional control valve. Since the connecting line 23 is in this switching position in connection with the first space 57, the fuel pump 11 feeds into the fuel line 7. A part of the flow of the fuel pump 11 passes through the connecting bore with throttle 55 in the piston 53 into the second space 59 and leads to it that the piston 53 moves against the force of the spring 63 in the direction of the spring 63.

5, the fourth embodiment is shown in a second switching position. The piston 53 is positioned such that the space 57 is hydraulically connected to both the connecting line 23 and the supply line 21. In this position, both the fuel line 7 and the jet pumps 13 are supplied with fuel by the fuel pump 11. 6 shows the third switching position of the 3/3 directional control valve 49. In this switching position, the fuel pump 11 delivers exclusively into the supply line 21 and not into the connecting line 23. This means that the entire delivery flow of the power flow pump 11 benefits the jet pumps 13.

In this fourth embodiment, the

Fuel line 7 filled as quickly as possible and at the same time driven the jet pumps 13 as soon as possible. in the

As a result, this leads to a very good starting behavior of the internal combustion engine, not shown, and it is possible to dimension the fuel pump 11 small, since it has to supply only the jet pumps 13 in continuous operation. Optionally, a throttle 65 can be provided in the connecting line 23, which leads to the fuel flow in the connecting line 23 being reduced and thus a larger part of the fuel flow conveyed by the fuel pump 11 flowing through the connecting bore 55 into the second space 59.

This increases the speed at which the piston 53 moves from the first to the third switching position.

All in the drawing, the description and the

Features represented in the claims can be essential to the invention both individually and in any combination.

Claims

Expectations

1. Fuel supply system for internal combustion engines with a fuel tank (1) and a baffle (5) arranged therein, with means (11, 13, 21) for filling the baffle (5) with fuel from the fuel tank (1) and with one, the baffle (5) hydraulically connecting to the internal combustion engine,

Fuel line (7), characterized in that the means (11, 13, 21) for filling the swirl pot (5) at least temporarily deliver fuel into the fuel line (7).

2. Fuel supply system according to claim 1, characterized in that a connecting line (23) is present between the means (11, 13, 21) for filling the swirl pot (5) and the fuel line (7).

3. Fuel supply system according to claim 1 or 2, characterized in that an overflow valve (25) is present between the means (11, 13, 21) for filling the swirl pot (5) and the fuel line (7).

4th Fuel supply system according to one of the preceding claims, characterized in that between the means (11, 13, 21) for filling the swirl pot (5) and the fuel line (7) is a throttle

(33) is present.

5. Fuel supply system according to one of the preceding claims, characterized in that a throttle (33) and a check valve (39) are present between the means (11, 13, 21) for filling the swirl pot (5) and the fuel line (7).

₆ . Fuel supply system according to one of claims 1 or 2, characterized in that a 3/2-way valve is present between the means (11, 13, 21) for filling the surge pot (5) and the fuel line (7), that the _{_3/2} -Way valve in its first switching position connects the means (11, ₁ 3, 21) for filling the baffle () to the fuel line (7), that the 3/2-way valve connects the means (11, 13, 21) in its second switching position for filling the surge pot (5) with the jet pump (s) (13).

₇ . Fuel supply system according to one of claims 1 or 2, characterized in that between the means (11, 13, 21) for filling the swirl pot (5) and the fuel line (7) there is a 3/3-way valve (49) that the 3/3 -way valve (49) in its first switch position, the means (11, 13, 21) connects to fill the _S chwalltopfs (5) with the fuel line (7) such that the 3/3 -way valve (49) in its second

Shift position, the means (11, 13, 21) for filling the surge pot (5) with the fuel line (7) and the or connecting the jet pump (13), and that the 3/3 _W egeventil ₍₄ 9) third in its switch position connects the means ( ₁₁ , ₁₃ , 2 ₁ ) for filling the swirl pot ⁽ 5 ⁾ with the jet pump (s) (13).

8. Fuel supply system according to one of claims 6 or 7, characterized in that the 2/3 or the 3/3-way valve _. (49) is spring-loaded in its first switching position and that the 2/3 or 3/3 directional control valve (49) against a spring force with fuel from the means (11, 13, 21) for filling the baffle (5) as

Working medium in the second and if necessary. third switch position is moved.

9. Fuel supply system according to one of the preceding claims, characterized in that the fill level of the swirl pot (5) is kept independent of the means (11, 13, 21) for filling the swirl pot (5) at least on the fill level of the fuel tank (1).

10. Fuel supply system according to one of the preceding claims, characterized in that the means (11, 13, 21) for filling the swirl pot (5) comprise an electric fuel pump (11).

11. The fuel supply system according to claim 10, characterized in that the fuel pump (11) drives at least one jet pump (13) arranged in the installed position in the vicinity of the low point (s) (3) of the fuel tank (1), and that the jet pump (13) or the jet pumps (13) deliver fuel into the baffle (5).

12. Fuel supply system according to one of the preceding claims, characterized in that the fuel line (7) has a check valve (9).