WO2010094574A1 - Device for restricting the throughflow quantity at a pump, and pump arrangement having a device of this type - Google Patents

Abstract

A device (2) for restricting the throughflow quantity at a pump (3), in particular at a suction-throttled delivery pump for fuel injection systems of air-compressing, self-igniting internal combustion engines, has a feed channel (4) on the suction side of the pump (3), which feed channel (4) is connected on an outlet side (8) to an inlet (9) of a pump (3), a cut-off channel (6) which can be connected on its inlet side (10) at least indirectly to an outlet (12) of the pump (3) and which opens on its outlet side (13) laterally at an opening point (14) into the feed channel (4), and a pressure control valve (7) which is arranged in the cut-off channel (6). Furthermore, a throttle (5) is provided which is arranged in the feed channel (4) between the opening point (14) and the outlet side (8) of the feed channel (4). A transverse flow is caused at the opening point (14) by a cut-off quantity which is discharged via the cut-off channel (6), which transverse flow is superimposed with a main flow through the feed channel (4). As a result, a lateral incident flow of the throttle (5) can be achieved, as a result of which the effective throttle diameter is reduced. A given pressure difference at the pump (3) can therefore be reduced. Furthermore, Furthermore, a pump arrangement (1) with the pump (3) and the device (2) for restricting the throughflow quantity is disclosed.

Description

description

title

Device for limiting the flow rate at a pump and

Pump assembly with such a device

State of the art

The invention relates to a device for

Flow limitation on a pump, in particular on a suction-throttled feed pump, and a pump assembly with such a device. Specifically, the invention relates to the field of fuel injection systems of air compressing, self-igniting internal combustion engines.

From DE 10 2004 028 999 Al a high-pressure pump for a fuel injection device of an internal combustion engine is known. The known high-pressure pump has at least one pump element, which has a driven in a lifting movement, in a cylinder bore of a pump housing part slidably guided pump piston which limits a pump working space in the cylinder bore. The pump working space can be filled with fuel via a suction valve during the suction stroke of the pump piston. In this case, the pump working chamber is connected via a running in the pump housing fuel inlet channel with a feed pump.

It is conceivable that the feed pump in the suction throttled Operation works. In this case, the flow rate and the adjusting pressure via a pressure regulating valve can be limited. However, there is the disadvantage that with large injection quantity requirement, the excess amount at the pressure control valve is small and thus the pressure for filling the feed pump low, while small injection quantity requirement, the excess amount at the pressure control valve is large and thus the pressure for filling the feed pump increases, although in In this case, an increase would not be required.

Disclosure of the invention

The inventive device for

Flow rate limitation with the features of claim 1 and the pump assembly according to the invention with the features of claim 11 have the advantage that an adapted to the needs flow rate limitation is ensured. Specifically, excessive pressure rise at the outlet of the pump can be prevented or at least reduced.

The measures listed in the dependent claims advantageous refinements of the device specified in claim 1 and the pump arrangement specified in claim 11 are possible.

It is advantageous that the throttle is oriented at least approximately on an axis of the inlet channel, along which the inlet channel extends at least between the outlet point and its outlet side. Furthermore, it is advantageous that an inlet of the throttle is arranged at least substantially in the region of the outlet point in the inlet channel. Due to the orientation of the throttle on the axis of the inlet channel, an optimal flow of the Throttle be enabled by the inlet channel. Via the diversion channel, which opens laterally into the inlet channel, a transverse flow can be generated, whereby a deliberate deterioration of the throttle coefficient of the throttle can be achieved. In this case, a flow separation within the throttle can be achieved due to the cross flow. The flow separation can increase advantageously with increasing Absteuermenge which is introduced via the Absteuerkanal at the confluence point in the inlet channel. Due to the arrangement of the throttle in the region of the discharge point, a particularly effective influencing of the throttle coefficient via the crossflow from the discharge channel is possible. In this particularly effective influencing of the throttle coefficient, a desired deterioration of the throttle coefficient can be achieved in a particularly effective manner. In this case, the throttle may be arranged at a suitable distance close to the discharge point of the diversion channel.

In an advantageous manner, a flow direction of the diversion channel at the outlet point is different from a flow direction of the inlet channel at the throttle. Here, it is also advantageous that the flow direction of the Absteuerkanals at the confluence with the

Flow direction of the inlet channel at the throttle at least approximately includes an angle, said angle is in a range of about 40 ° to about 90 °. Here is a geometry optimization by a

Flow simulation calculation or the like possible. As a result, a particularly effective influencing of the main flow through the crossflow can be achieved.

Advantageously, the overflow valve is designed as a pressure control valve. It is further advantageous that the pressure control valve controls a Absteuermenge through the Absteuerkanal in response to a pressure difference between the input side of the Absteuerkanals and the output side of the Absteuerkanals. With low volume requirements and thus relatively high pressure thus an increase in the Absteuermenge can be achieved via the diversion channel, which leads to a deterioration of the throttle coefficient due to the increase of the cross flow. Thus, the flow rate through the throttle and thus the pump reduces, which reduces the given pressure difference. As a result, an advantageous flow rate limitation can be created, with the service life and power loss being optimized.

It is advantageous that the diversion channel at its inlet and outlet sides and / or the inlet channel at the outlet point are designed such that hydraulic losses at the outlet point are avoided. As a result, in the sense of a low efficiency of the throttle can be achieved with a correspondingly large cross-flow, that even the lowest possible hydraulic losses are caused to generate the cross flow. It is also advantageous that the throttle is designed so that an increasing flow separation occurs within the throttle with increasing Absteuermenge, which flows through the Absteuerkanal in the inlet channel as a cross-flow. For example, the throttle may be configured in an advantageous manner as a cylindrical bore. The throttle can be integrated or installed in a suitable manner in the inlet channel, for example by drilling or pressing.

Brief description of the drawings Preferred embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawings, in which corresponding elements are provided with corresponding reference numerals. It shows:

1 shows a pump arrangement with a device for flow rate limitation in a schematic representation according to an embodiment of the invention in a state with a relatively low Absteuermenge and

Fig. 2, the pump assembly shown in Fig. 1 with the means for limiting the flow rate according to the embodiment of the invention in a state with a relatively large Absteuermenge.

Embodiments of the invention

1 shows a pump arrangement 1 with a device 2 for restricting the flow rate to a pump 3. The pump 3 is part of the pump arrangement 1, but no part of the device 2. The device 2 for

Flow rate limitation and the pump assembly 1 with this device 2 can be used in particular for a fuel injection system of air-compressing, self-igniting internal combustion engines. The pump 3 is configured as a suction-throttled feed pump. A preferred use of the pump assembly 1 and the device 2 is for a feed pump for supplying fuel to a high-pressure pump of a fuel injection system with a common rail that stores diesel fuel under high pressure. The inventive device 2 for However, flow rate limitation and the pump arrangement 1 according to the invention are also suitable for other applications.

The device 2 has an inlet channel 4 on the suction side of the pump 3, which has a throttle 5, and a discharge channel 6 also on the suction side of the pump 3, in which an overflow valve 7 is arranged, which is designed as a pressure control valve 7. The inlet channel 4 is connected at its output side 8 to an inlet 9 of the pump 3. The diversion channel 6 is connected at its input side 10 by means of a fuel line 11 to an outlet 12 of the pump 3. The Absteuerkanal 6 branches off from the fuel line, which leads, for example, to a high pressure pump of a fuel injection system. The discharge channel 6 opens at its outlet side 13 at an outlet point 14 laterally into the inlet channel 4. The throttle 5 is arranged between the discharge point 14 and the output side 8 of the inlet channel 4 in the inlet channel 4.

The inlet channel 4 has an axis 20. The inlet channel 4 extends along the axis 20. In particular, the inlet channel 4 extends between the outlet point 14 and its outlet side 8 along the axis 20. The throttle 5 is aligned with the axis 20 of the inlet channel 4. In this case, the throttle 5 is configured by a cylindrical bore. As a result, a flow direction 21 of the inlet channel 4 on the throttle 5 is parallel to the axis 20 of the inlet channel 4.

The diversion channel 6 has an axis 22 on its output side 13. A flow direction 23 of the diversion channel 6 at the point of discharge 14 is parallel to the axis 22 oriented. In this embodiment, the axis 22 of the Absteuerkanals 6 includes with the axis 20 of the inlet channel 4 at the discharge point 14 an angle 24 of about 90 °. The flow direction 23 of the diversion channel 6 at the point of discharge 14 is different from the flow direction 21 of the inlet channel 4 at the throttle 5.

An inlet 25 of the throttle 5 is located in the region of the discharge point 14 in the inlet channel. 4

Fuel flows in a main flow direction to the throttle 5 via the inlet channel 4. A transverse flow via the outlet channel 6 in the flow direction 23, which depends on the amount of fuel removed via the outlet channel 6 by the pressure regulating valve 7, is added to this main flow. In this case, a situation is shown in Fig. 1, in which no or only a relatively small Absteuermenge occurs. Thus results in the inlet channel 4 in front of the inlet 25 of the throttle 5, a flow

26, which is determined essentially by the main flow through the inlet channel 4. This results in an ideal throttle effect of the throttle 5. The throttle coefficient is therefore optimal.

Fig. 2 shows the pump assembly 1 shown in Fig. 1 with the means 2 for limiting the flow rate at the pump

3 in a state in which a relatively large Absteuermenge is diverted via the Absteuerkanal 6 and is returned to the inlet channel 4.

The pressure control valve 7 controls the Absteuermenge through the Absteuerkanal 6 in response to a pressure difference between the input side 10 of the Absteuerkanals 6 and the Output side 13 of the Absteuerkanals 6. In the situation shown in FIG. 2, the pressure difference at the pressure control valve 7 is relatively large. This can be caused by a consumer downstream of the pump arrangement 1, in particular a high-pressure pump, polling a relatively small quantity of fuel. This results in the output 12 of the pump 3 to a relatively large pressure, which thus also prevails on the input side 10 of the Absteuerkanals 6 and acts on the pressure control valve 7. However, this causes the Absteuerung a relatively large Absteuermenge via the Absteuerkanal 6, which flows on the output side 13 as a cross-flow in the inlet channel 4. This transverse flow is illustrated schematically in FIG. 2 by a flow pattern 27.

The diversion channel 6, in particular the outlet side 13 of the diversion channel 6, and the inlet channel 4, in particular the region of the inlet channel 4 at the outlet point 14, are designed so that hydraulic losses at the point of discharge 14 are avoided. The crossflow added via the outlet channel 6 of the main flow in the inlet channel 4 can thereby flow into the inlet channel 4 substantially without any loss. Due to the superimposition of the cross flow to the main flow, there is a flow separation in the throttle 5. The throttle 5 is designed so that with increasing cross flow, that is, with increasing Absteuermenge that flows through the discharge channel 6 in the inlet channel 4, an increasing

Flow separation within the throttle 5 occurs. Due to the flow separation within the throttle 5 of the wall decreases the effective throttle diameter. As a result, the throttle coefficient deteriorates, that is, the throttle effect of the throttle 5 increases. Thus reduced at a given pressure difference, the flow rate through the throttle 5. This has a reducing effect on the prevailing at the output 12 of the pump 3 and thus in the fuel line 11 pressure.

For example, the pump assembly 1 can be used for a high-pressure pump of a fuel injection system with a common rail, the pump 3 as a mechanical prefeed pump, such as external gear pump used. The pump 3 preferably operates largely in the suction-throttled operation in order to limit the delivery rate and thus the pressure which is established via the pressure regulating valve 7. For example, fuel can be conveyed out of a tank via the inlet channel 4, wherein the amount of diversion via the outlet channel 6 is likewise added to the inlet channel 4.

However, there is the problem that at large injection quantity requirement, the excess amount at the pressure control valve 7 is small and thus the pressure for filling a downstream consumer, in particular a pump working space is low, while at a small injection quantity requirement, the excess amount at the pressure control valve 7 becomes large, whereby the Pressure for filling a consumer, in particular a pump working space increases, although in this case, such an increase is not required.

In the case of the pump arrangement 1 of the exemplary embodiment, in the case of a small injection quantity requirement, the throttle coefficient of the throttle 5 serving as intake throttle is changed such that the throttle 5 represents a greater resistance, whereby the pressure increase upstream of the pressure control valve 7 on the pump 3 less fails.

This is achieved by a lateral flow of the throttle 5 of the flow, in which the main flow is superimposed by the inlet channel 4, a cross flow from the Absteuerkanal 6. In this case, the flow direction 23 of the diversion channel 6 differs from the flow direction 21 of the inlet channel 4. For example, the two flow directions 21, 23 may enclose an angle from a range of about 40 ° to about 90 °. The inlet via the inlet channel 4 is optimally carried out, since the throttle 5 is located on the axis 20 of the inlet channel 4 and is aligned with the axis 20. The inlet from the diversion channel 6, however, takes place under a flow direction 23 swung out of the flow direction 21.

In the case of a tight balance of quantities, which represents a boundary condition and in which a minimum amount of removal is achieved at the pressure regulating valve 7 according to the situation illustrated in FIG. 1, the maximum amount of fuel flows through the throttle 5.

In the case of a sufficient amount in which the Absteuermenge at the pressure control valve 7 is not minimal, the proportion of not optimally flowing to the throttle 5 amount, that is, the cross-flow increases, whereby the throttle coefficient of the throttle 5 deteriorates. Thus, the total amount flowing through the throttle 5 decreases until an equilibrium state is established. This case occurs, for example, at higher inlet pressures to the pump 3 or at a small decrease in volume, for example, in overrun operation of an internal combustion engine on. The reduced Absteuermengen lead according to the characteristic of the pressure control valve 7 to a reduced pressure on all components involved and thus to a reduced power loss and increased life. Furthermore, there is a reduced Absteuermengenvarianz and thus a reduced pressure variance. This can already be achieved by a favorable arrangement of the discharge point 14 in the run-up to the throttle or the like responsible for the throttling, which forms the throttle 5, a beneficial effect, whereby the pump assembly 1 can be designed inexpensively.

In order to achieve an advantageous flow against the throttle 5 via the diversion channel 6 with a correspondingly large cross flow, deflections, cross-sectional constrictions and the like within the Absteuerkanals 6 are to be avoided as possible.

During operation of the pump assembly 1, various situations may occur, with two possible situations being illustrated in FIGS. 1 and 2. During operation of the pump arrangement 1, the throttling coefficient of the throttle 5, which is impaired by the transverse flow, leads to a reduced throttle flow through the throttle 5, which in turn reduces the diversion amount through the bypass duct 6 via the pressure regulating valve 7 until an equilibrium is established between the two effects.

The invention is not limited to the described embodiments.

Claims

claims 1. Device (2) for limiting the flow rate at a pump (3), in particular at a suction-throttled feed pump for fuel injection systems of air-compressing, self-igniting internal combustion engines, with an inlet channel (4) on the suction side of the pump (3), the at one Output side (8) at least indirectly with an input (9) of the pump (3) is connected to a Absteuerkanal (6) at its input side (10) at least indirectly with an output (12) of the pump (3) is connectable and the on its output side (13) at an opening point (14) opens laterally into the inlet channel (4), a in the Absteuerkanal (6) arranged overflow valve (7) and a throttle (5) between the orifice (14) and the output side (8) of the inlet channel (4) in the inlet channel (4) is arranged. 2. Flow restriction device according to claim 1, characterized in that the throttle (5) at least approximately on an axis (20) of the inlet channel (4), along which the inlet channel (4) at least between the orifice point (14) and its Output side (8) extends, is aligned. 3. Flow restriction device according to claim 1 or 2, characterized in that an input (25) of the throttle (5) at least in Essentially in the area of the confluence point (14) in the Inlet channel (4) is arranged. 4. Device for limiting flow rate according to one of claims 1 to 3, characterized in that a flow direction (23) of the Absteuerkanals (6) at the discharge point (14) is different from a flow direction (21) of the inlet channel (4) on the throttle ( 5). 5. Device for flow rate limitation according to claim 4, characterized in that the flow direction (23) of the Absteuerkanals (6) at the discharge point (14) with the flow direction (21) of the inlet channel (4) on the throttle (5) at least approximately an angle (24) which is in a range of about 30 ° to about 100 °, in particular in a range of about 40 ° to about 90 °. 6. Device for flow rate limitation according to one of claims 1 to 5, characterized in that the overflow valve (7) is designed as a pressure control valve (7). 7. A flow rate limiting device according to claim 6, characterized in that the pressure control valve (7) a Absteuermenge through the Absteuerkanal (6) in response to a pressure difference between the input side (10) of the Absteuerkanals (6) and the output side (13) of the Absteuerkanals (6) controls. 8. Flow rate limiting device according to one of claims 1 to 7, characterized in that the diversion channel (6) at its inlet side (10) and / or at its outlet side (13) and / or the inlet channel (4) at the outlet point (14 ) are designed so that hydraulic losses at the discharge point (14) are minimized. 9. Device for limiting the flow rate according to one of claims 1 to 8, characterized in that the throttle (5) is designed so that with increasing Absteuermenge which flows via the Absteuerkanal (6) in the inlet channel (4), an increasing flow separation within the throttle (5) occurs. 10. Flow rate limiting device according to one of claims 1 to 9, characterized in that the throttle (5) is at least substantially configured as a cylindrical bore. 11. Pump arrangement (1), in particular for fuel injection systems of air-compressing, self-igniting internal combustion engines, with a pump (3) and a device (2) for limiting the flow rate according to one of claims 1 to 10, wherein the output side (8) of the inlet channel (4) at least is indirectly connected to the input (9) of the pump (3) and wherein the input side (10) of the Absteuerkanals (6) is at least indirectly connected to the output (12) of the pump (3).