SWITCHED SUCTION JET PUMP

Abstract

The invention relates to a single-stage or multistage suction jet pump comprising a propelling nozzle (5), one or more suction nozzles (2), a diffuser (7), and a volume flow limiting valve in or directly in front of the propelling nozzle. The volume flow limiting valve has a valve element (4) in the overpressure region (1) of the suction jet pump, said valve element having an opening (8) with a cross-sectional area which is smaller than the cross-sectional area of the propelling nozzle (5). The valve element spans at least one additional gap opening (9) which first releases the cross-section of the gap opening (9) when the pressure difference between the overpressure region (1) and the suction region (2) increases and which switches in the event of a defined large pressure drop and the valve element (4) reduces or closes the cross-section of the gap opening (9) such that the volume flow flowing over the opening (8) is limited to a defined level even in the event of a further increasing pressure difference.

Claims

1. A single-stage or multistage suction jet pump, comprising a jet nozzle, one or more suction nozzles in an intake zone, and a diffuser, said suction jet pump has a valve body in or directly upstream from the jet nozzle in the overpressure zone of the suction jet pump, said valve body spanning at least one other gap, which when the pressure difference between the overpressure zone and the intake zone increases, at first opens the cross-section of the gap, but switches at a defined high pressure drop, and the valve body reduces the cross-section of or closes the gap in such a way that the volume flow through the opening is limited to a defined level even when the pressure difference increases further.

2. The suction jet pump according to claim 1, wherein said valve body comprises an opening whose cross-sectional area is smaller than the cross-sectional area of the jet nozzle.

3. The suction jet pump according to claim 1, characterized in that said valve body (4) is designed as a spring sheet attached under a bias by a downholder on the inlet of the suction jet pump.

4. (canceled)

5. A process for ventilating crankcases of an internal combustion engine, providing a single-stage or multistage suction jet pump, comprising a jet nozzle, one or more suction nozzles in an intake zone, and a diffuser, said suction jet pump has a valve body in or directly upstream from the jet nozzle in the overpressure zone of the suction jet pump, said valve body spanning at least one other gap, which when the pressure difference between the overpressure zone and the intake zone increases, at first opens the cross-section of the gap, but switches at a defined high pressure drop, and the valve body reduces the cross-section of or closes the gap in such a way that the volume flow through the opening is limited to a defined level even when the pressure difference increases further; and inserting the suction jet pump in an internal combustion engine.

Description

[0009] FIG. 1 shows the invention with a self-resilient valve body in a non-throttled switch position.

[0010] FIG. 2 shows the invention with a self-resilient valve body in a throttled switch position.

[0011] FIG. 3 shows a possible curve progression of the jet and suction stream as a function of the acting boost pressure.

[0012] In particular, the invention consists of a single-stage or multistage suction jet pump as shown in FIGS. 1 and 2, comprising a jet nozzle 5, a diffuser 7, and optionally further nozzles 6. Upstream from the jet nozzle 5, there is the overpressure zone (1), which may be the boost pressure of a turbo engine, for example. The overpressure accelerates the jet fluid through the jet nozzle 5, so that the maximum speed is observed behind the nozzle. The dynamic pressure is thereby increased in this zone. For reasons of energy preservation, the static pressure drops. Air is thereby sucked from the suction zone 2 and then flows with the jet air through the diffuser 7, where the flow is decelerated. This can be utilized, for example, to produce a negative pressure in a crankcase or in a tank. The overall flow 3 can then be returned to the intake air of the internal combustion engine (for example, upstream from the compressor).

[0013] According to the invention, it is particularly preferred if the device for limiting the jet stream (volume flow limiting valve) in the overpressure zone of the suction jet pump has a valve body 4, especially one comprising an opening 8 whose cross-sectional area is smaller than the cross-sectional area of the jet nozzle 5.

[0014] Because the limiting function is positioned upstream from or in the jet nozzle 5, almost the complete available boost pressure can be used to drive the suction jet pump. Further, the construction of the system is very compact. Also, the number of components is reduced.

[0015] The limitation of the jet stream according to the invention is preferably solved by a (resilient) valve body 4 that is mounted immediately upstream from the jet nozzle 5 of the suction jet pump.

[0016] The resilience is preferably realized by spring arms in the valve body 4. In this case, the valve body 4 rests, for example, on a support surface 11 in the body of the jet nozzle 5. Alternatively, however, a compression or tension spring may also be used. Further, the resilient element may be biased to set the switch point of the valve body 4. This can be realized, for example, by a downholder 10.

[0017] FIG. 1 shows that the valve body 4 in its original state has a distance to the jet nozzle 5, so that a gap 9 is formed between the valve body 4 and the body of the jet nozzle 5. The jet fluid flows through the valve body 4 in this state over the gap 9. Further, the fluid may flow through the opening in the valve body 4, if any. When the boost pressure increases, the jet stream increases, too (FIG. 2). Because of the jet stream and the Venturi effect, formation of the overall flow 3 takes place.

[0018] The present invention provides a mass flow control with a defined valve characteristic diagram and a small construction space. By means of the valve body 4, especially a spring sheet, the cross-section of the gap 9 through which the flow occurs is reduced between the overpressure zone 1 and the negative pressure zone, and thus the propellant mass flow is controlled.

[0019] Another advantage of the present invention resides in the fact that there is only one movable element, namely the valve body 4, especially a spring sheet.

[0020] The valve body 4 serves to control the cross-section through which the flow occurs, preferably in the form of a spring sheet. The spring sheet may be mounted, for example, in the overpressure zone 1 under a defined bias in order to give way for the gas flow through the gap 9. When the pressure drop increases because of a higher boost pressure, the valve body 4 will move towards the wall of the jet nozzle 5 up to the point in which the gap 9 is completely closed.

[0021] Depending on the jet stream, the valve body 4 produces a pressure loss. When this pressure loss exceeds the resilient force of the valve body, the latter will move towards the jet nozzle 5, slowly closing the gap 9. When the boost pressure increases, the jet stream is reduced. The same applies to the suction stream in the suction zone 2. At the end of the closing process, the valve body 4 creates an almost perfect seal on the body of the jet nozzle 5, so that the jet fluid can flow into the suction jet pump only through the opening in the jet nozzle 5, as shown in FIG. 2.

[0022] The smaller opening in the valve body 4 limits the jet stream. However, because of the increase of the density of the fluid at higher boost pressures, another increase, albeit flat, of the jet stream occurs. The suction stream also increases further.

[0023] Preferably, the valve body 4 is to be designed in a way that the pressure loss is low, in order that the complete boost pressure can be utilized for driving the suction jet pump, if possible.

[0024] Another embodiment of the present invention relates to the use of the device defined above for the crankcase ventilation of an internal combustion engine in a housing between a crank chamber of a crankcase and an intake tract or tank ventilation.

LIST OF REFERENCE SYMBOLS

[0025] 1 overpressure zone (for example, boost pressure)

[0026] 2 intake zone (for example, crankcase or tank ventilation)

[0027] 3 overall flow (for example, upstream from the compressor)

[0028] 4 valve body

[0029] 5 jet nozzle

[0030] 6 second nozzle (optional)

[0031] 7 diffuser

[0032] 8 opening in valve body

[0033] 9 gap below valve body

[0034] 10 downholder/pretensioner

[0035] 11 support for valve body (metal sheet variant)