Suction Jet Pump

Abstract

The invention relates to a suction jet pump (8), consisting of a driving jet nozzle (10), a mixing tube (11), an intake opening (12), a working-fluid line (7) connected to the driving jet nozzle (10), and a valve (9) which is arranged with the working-fluid line (7) and whose housing (13) has an inlet (14) and an outlet (15). A throughflow opening (17) with a valve body (18) on both sides of the throughflow opening (17) is arranged in the housing (13) in such a way that the throughflow opening (17) can be closed on both the inlet side and the outlet side, and that at least one spring (25, 27, 28) is arranged inside the housing (13) in such a way that it holds the valve body (18) in a position closing the throughflow opening (17) on the outlet side until the system pressure is reached.

Description

The subject matter of the invention is a suction jet pump, comprising a driving jet nozzle, a mixing tube, an intake opening, a working-fluid line connected to the driving jet nozzle and a valve which is arranged in the working-fluid line. Suction jet pumps are used in fuel tanks of motor vehicles.

Such suction jet pumps are used in fuel tanks in order to supply fuel from various regions of the fuel tank to a feed unit, which feed unit feeds fuel from the fuel tank to an internal combustion engine of the motor vehicle. In order to drive the suction jet pump, a portion of the fuel fed by the fuel pump is branched off and supplied via the working-fluid line of the suction jet pump. When starting the internal combustion engine, the fuel pump should feed fuel in a sufficient quantity to the internal combustion engine as fast as possible. To this end, a valve is arranged in the working-fluid line, which valve only opens when the system pressure is reached so that, particularly in the event of a starting process, all the fed fuel is first supplied to the internal combustion engine.

In order to improve the starting behavior of the motor vehicle, it is known to increase the pressure in the feed line for a short time. To this end, the flow rate of the fuel pump is increased for a short time during the starting process. However, the effect of the valve in the working-fluid line is thus cancelled out, which valve is supposed to release the working-fluid line only when the system pressure is reached. This has the disadvantage that, as a result of the increase in pressure, the valve opens, which valve is supposed to separate the suction jet pump from the fuel supply for the starting process. A portion of the fuel thus reaches the suction jet pump and is not available for the internal combustion engine. In order to nevertheless ensure a sufficient supply of the internal combustion engine with fuel during a starting process, the fuel pump must be dimensioned such that it, as well as the increased demand on the internal combustion engine, also supplies the increased feed quantity for the suction jet pump as a result of the opened valve. These two increased feed quantities lead to an overdimensioning of the fuel pump. Such fuel pumps require significantly more space and are more costly.

The object of the invention is therefore to create a suction jet pump which only operates when the fuel supply system operates with system pressure.

According to the invention, the object is achieved in that a throughflow opening is arranged in the housing, that a valve body is arranged on both sides of the throughflow opening such that the throughflow opening can be closed both on the inlet side and on the outlet side, and that at least one spring is arranged within the housing such that it holds the valve body in a position closing the throughflow opening on the outlet side until the system pressure is reached.

The valve arranged in the working-fluid line of the suction jet pump is closed in the depressurized state in that the spring holds the valve body on the outlet side in a position closing the throughflow opening. As soon as the fuel pump reaches system pressure, the force acting on the valve body is larger than the spring force, as a result of which the valve body is moved out of the position closing the throughflow opening on the outlet side. The valve is thus open and fuel can reach the suction jet pump. If the pressure rises above the system pressure during a starting process, the valve body is moved further counter to the spring force until it reaches a position closing the throughflow opening on the inlet side, as a result of which the valve closes. The valve according to the invention allows operation of the suction jet pump in a presettable pressure range, wherein the suction jet pump is switched off above and below this pressure range. This means that the suction jet pump operates only under normal conditions, while, in critical situations in which the supply of the internal combustion engine with fuel is supposed to be ensured, the fuel fed by the fuel pump only reaches the internal combustion engine. The fuel pump can thus be of smaller dimensions since the flow rate of the fuel pump is only determined by the internal combustion engine and the suction jet pump in the case of system pressure, while in the case of operation of the fuel pump above the system pressure the flow rate is exclusively determined by the internal combustion engine as a result of the switching off of the suction jet pump.

The throughflow opening is of a particularly simple configuration if it is embodied as a diaphragm.

A reliable sealing off is achieved according to another advantageous configuration in that the valve body possesses two sealing elements which interact on the inlet side and the outlet side with a sealing seat at the throughflow opening.

The sealing elements of the valve body respectively comprise in a simple and thus low-cost formation an annular disk, which annular disks are arranged on the valve body.

The structure of the valve body is simplified according to another configuration if the sealing elements are arranged on both sides of the diaphragm relative to the direction of flow such that they surround the throughflow opening.

A defined position of the valve body in the open position in the case of system pressure is achieved in a further configuration in that a second spring is arranged relative to the first spring, wherein the first spring is designed with respect to the opening pressure and the second spring allows a further movement of the valve body only above the system pressure. In this manner, a movement of the valve body is prevented in the case of a system pressure in the open position.

The springs used can be both pressure springs and tension springs, wherein the springs are arranged between the housing and the valve body.

Insofar as pressure springs are used, these can also be arranged in a different configuration between the valve body and the throughflow opening. For improved guidance and receiving of the pressure springs, a shoulder is formed on the valve body in a further configuration.

The invention is described in greater detail with reference to several exemplary embodiments. In the drawings

FIG. 1: shows a schematic representation of a fuel tank with a feed unit and a suction jet pump according to the invention,

FIGS. 2 to 4: show a schematic representation of the valve of the suction jet pump from FIG. 1 in various positions and

FIGS. 5 to 7: show further embodiments of the valve according to FIG. 2.

FIG. 1 shows schematically a fuel tank 1 of a motor vehicle with a feed unit 2 arranged therein for feeding fuel to an internal combustion engine 3. Feed unit 2 has a fuel pump 5 driven by an electric motor 4 and is connected via a feed line 6 to internal combustion engine 3. A working-fluid line 7 leads from feed line 6 to a suction jet pump 8 which feeds fuel to feed unit 2. As well as working-fluid line 7, suction jet pump 8 comprises a valve 9 arranged in working-fluid line 7, a driving jet nozzle 10 connected to working-fluid line 7, a mixing tube 11 and an intake opening 12, by means of which fuel is sucked into mixing tube 11 by the fuel escaping from driving jet nozzle 10.

FIG. 2 shows schematically a first embodiment of valve 9 from FIG. 1. The direction of flow is marked by an arrow. Valve 9 comprises a valve housing 13 with an inlet 14 and an outlet 15. A diaphragm 16 is arranged in valve housing 13, which diaphragm 16 has a throughflow opening 17. Valve 9 possesses a valve body 18 with two disk-like regions 19, 20 which are connected to one another via a central part penetrating through throughflow opening 17 such that disk-shaped regions 19, 20 are arranged on the inlet side and outlet side of throughflow opening 17. Both regions 19, 20 have disk-shaped sealing elements 21, 22 which interact with sealing seats 23, 24 of diaphragm 16. A pressure spring 25 is arranged on the outlet side, which pressure spring 25 moves valve body 18 counter to the direction of flow. The representation shows the depressurized state in which no fuel flows through valve 9. As a result of the spring force, valve body 18 lies on the outlet side against diaphragm 16, wherein sealing element 21 interacts with sealing seat 23 and thus closes throughflow opening 17.

FIG. 3 shows valve 9 in the case of system pressure. The fuel flowing in with system pressure via inlet 14 generates a force acting in the direction of flow, which force opposes the spring force. Pressure spring 25 is therein designed such that in the case of system pressure valve body 18 is moved so far in the direction of flow that both sealing elements 21, 22 are not in contact with sealing seats 23, 24. Throughflow opening 17 is thus free and the fuel can flow through valve 9 to outlet 15 and further to the suction jet pump.

FIG. 4 shows valve 9 during a starting process of the internal combustion engine. Herein, the fuel pump is actuated such that the pressure in the feed line is increased for a short time. The increased pressure thus also acts in the working-fluid line and in inlet 14 of valve 9. Since the spring force generated by pressure spring 25 is smaller than the force acting on valve body 18 as a result of the increased pressure, valve body 18 is moved further in the direction of flow until sealing element 22 of region 20 lies against inlet-side sealing seat 24 of diaphragm 16. Throughflow opening 17 is thus closed so that no fuel reaches the suction jet pump during the starting process.

Valve 9 shown in FIG. 5 differs from the valve according to FIG. 2 in the arrangement of pressure spring 25. Pressure spring 25 is supported between diaphragm 16 and region 20 of valve body 18. Region 20 possesses a shoulder 26 for this purpose. Shoulder 26 is used on the one hand as a guide for pressure spring 25 and ensures on the other hand sufficient space in the axial extension if pressure spring 25 is compressed.

FIG. 6 shows valve 9 with a tension spring 27 which is fastened on the inlet side between housing 13 and valve body 18 and moves valve body 18 in the depressurized state counter to the direction of flow such that sealing element 21 interacts with sealing seat 23 of diaphragm 16 such that valve 9 is closed.

In a further configuration, FIG. 7 shows valve 9 in the case of system pressure. Herein, two pressure springs 25, 28 are arranged on the outlet side. Pressure spring 25 behaves in accordance with its design as in FIGS. 2 to 4. Pressure spring 28 is harder and is designed with a shorter length, wherein the length and the spring rigidity of pressure spring 28 are selected such that, in the case of system pressure, valve body 18 is moved in the direction of flow as a result of the force acting on it until it lies against pressure spring 28 without pressure spring 28 being compressed. Valve 9 in an open position is located in this position. In this manner, a defined position is created for valve body 18 in the case of system pressure. In the case of a further pressure increase in the event of a starting process, the force acting on valve body 18 is larger than the spring forces of pressure springs 25, 28 such that the valve behaves as in FIG. 4.

Claims

1.-10. (canceled)

11. A suction jet pump, the suction jet comprising: a driving jet nozzle;a mixing tube arranged downstream of the driving jet nozzle;an intake opening arranged between the mixing tube and the driving jet nozzle;a working-fluid line coupled to the driving jet nozzle; anda valve arranged in the working-fluid line, the valve comprising: a valve housing, having an inlet and an outlet,a throughflow opening arranged in the housing between the inlet and the outlet;a valve body arranged on both sides of the throughflow opening, the valve body adapted to close the throughflow opening on an inlet side and on an outlet side; andat least one spring arranged within the housing and coupled to the valve body,wherein the at least one spring is adapted to hold the valve body in a position closing the throughflow opening until the system pressure is reached.

12. The suction jet pump according to claim 11, wherein the throughflow opening is a diaphragm.

13. The suction jet pump according to claim 11, wherein the valve body comprises: a first sealing element; anda second sealing element,wherein the first sealing element and the second sealing element are adapted to cooperate with a respective inlet sealing seat and output sealing seat on the inlet side and the outlet side of the throughflow opening.

14. The suction jet pump according to claim 13, wherein the first sealing element and the second sealing element are annular disks.

15. The suction jet pump according to claim 12, wherein a first sealing element and a second sealing element are arranged on both sides of the diaphragm relative to the direction of flow such that the first sealing element and the second sealing element surround the throughflow opening

16. The suction jet pump according to claim 11, further comprising a second spring arranged within the housing and coupled to the valve body, wherein the first spring is designed with respect to the opening pressure of the valve and the second spring allows a further movement of the valve body only above the system pressure.

17. The suction jet pump according to claim 11, wherein the at least one spring is a pressure spring.

18. The suction jet pump according to claim 11, wherein the at least one spring is a tension spring.

19. The suction jet pump according to claim 17, wherein the at least one spring is arranged between the housing and the valve body.

20. The suction jet pump according to claim 17, wherein the at least one spring is arranged between the valve body and the throughflow opening.

21. The suction jet pump according to claim 11, further comprising a shoulder formed on the valve body for receiving the at least one spring.

22. The suction jet pump according to claim 11, wherein the at least one spring is adapted to hold the valve body in a position closing the throughflow opening on the outlet side until the system pressure is reached.

23. The suction jet pump according to claim 18, wherein the at least one spring is arranged between the housing and the valve body.

24. The suction jet pump according to claim 11, wherein the at least one spring is adapted to hold the valve body in a position closing the throughflow opening on the inlet side until the system pressure is reached.

25. A suction jet pump, the suction jet comprising: a driving jet nozzle;a mixing tube arranged downstream of the driving jet nozzle;an intake opening arranged between the mixing tube and the driving jet nozzle; anda valve coupled to the driving jet nozzle in the working-fluid line, the valve comprising: a valve housing having an inlet and an outlet,a throughflow opening arranged in the housing between the inlet and the outlet, the throughflow opening having an inlet sealing seat on an inlet side and an output sealing seat and an outlet side of the throughflow opening;a valve body having a first sealing element arranged on the first side of the throughflow opening and a second sealing element arranged on the second side of the throughflow opening, the first sealing element and the second sealing element are adapted to cooperate with the respective inlet sealing seat and output sealing seat to close the throughflow opening on one of the inlet side and the outlet side of the throughflow opening; andat least one spring arranged within the housing and coupled to the valve body,wherein the at least one spring adapted to hold the valve body in a position closing the throughflow opening until the system pressure is reached.

26. The suction jet pump according to claim 25, wherein the at least one spring adapted to hold the valve body in a position closing the throughflow opening on the outlet side until the system pressure is reached.

27. The suction jet pump according to claim 25, wherein the at least one spring adapted to hold the valve body in a position closing the throughflow opening on the inlet side until the system pressure is reached.