WO2012110261A1 - High-pressure pump for a fuel injection device - Google Patents

Abstract

A high-pressure pump for a fuel injection device of an internal combustion engine, having a pump housing 6 with a pump interior 5 into which an inlet 4 for fuel opens out, and having a metering unit 12 for metering fuel into a pump working chamber 11, wherein the metering unit 12 is connected to the pump interior 5. According to the invention, a high-pressure pump for a fuel injection device is provided which realizes an increase in efficiency through a reduction in pressure losses. This is achieved in that a flow connection which directly connects the pump interior 5 to the metering unit 12 is formed into the pump housing 6.

Description

 Description Title:

High pressure pump for a fuel injection device

The invention relates to a high-pressure pump for a fuel injection device of an internal combustion engine, comprising a high-pressure pump housing with a Pumpeninnen nenraum into which opens a feed for fuel, and a metering unit for metering fuel into a pump working space, wherein the metering unit is connected to the pump interior.

State of the art

Such a high-pressure pump is known from DE 10 2008 043 444 A1. This high-pressure pump is designed in particular for a common-rail injection system and has a prefeed pump designed as a piston pump. The provision of the prefeed pump as a piston pump allows a significant cost advantage in terms of manufacturing costs compared to gear pumps or vane pumps, since a piston pump is comparatively simple in construction and easy to manufacture. A metering unit for metering fuel into two pump working spaces is connected to the pump interior via a space connection.

Another high-pressure pump is known from DE 10 2009 001 560 A1. This high-pressure pump has a pump housing which has an inlet and a drain for fuel in the region of a cylinder head. The inlet is connected via a supply line with a metering unit, wherein the supply line opens radially into the metering unit. The metering unit is further arranged directly above a pump working space and connected with this via a channel with an inserted Saufventil.

The invention has for its object to provide a high-pressure pump for a fuel ei n- injection device, which has an increase in pressure by reducing pressure loss. Disclosure of the Invention Advantages of the Invention

This object is achieved in that in the high-pressure pump housing a the pump interior directly connected to the metering unit flow connection is recessed. This embodiment has the advantage that previous complicated and different deflections having connection holes can be avoided. These previous connection bores cause a considerable pressure loss or throttling effect due to different flow deflections. The fact that now a flow connection is created without deflections, the pressure loss is minimized, which allows better efficiency, better filling and higher delivery of the high-pressure pump. Furthermore, a cost reduction in the production of the high-pressure pump is achieved by the direct flow connection.

In a further development of the invention, the flow connection is a bore which, in a further embodiment, in turn connects the pump interior directly to an inlet in the metering unit. The bore is thus arranged so that the inlet is connected to the metering unit without any impairment by, for example, a deflection with the pump interior. The pump interior is fuel-filled at the high-pressure pump, wherein the fuel is supplied via an inlet, which is connected to a fuel low-pressure system. In addition, the location of the bore makes it possible to ensure better mixing of the fuel introduced into the interior of the pump, since the inlet and a drain are not directly adjacent to one another. As a result, short-circuit currents of fuel are avoided. This embodiment ensures better cooling of the high pressure pump, which also contributes to an increase in efficiency.

In a further embodiment of the invention, the bore is arranged in extension of a receiving recess for the metering unit in the high-pressure pump housing. This embodiment provides in a particularly simple form the direct flow connection between the metering unit and the pump interior.

In a further development of the invention, the diameter of the bore corresponds at least approximately to the diameter of the inlet in the metering unit. By this configuration, throttling points, which in turn lead to pressure losses avoided. In a further embodiment of the invention, the bore opens axially into the inlet of the metering unit. This embodiment also avoids any pressure losses due to deflections.

In a further development of the invention, the inlet of the metering unit is connected via a metering valve with a Zumessauslass and the axial inlet flow is deflected into a radial outlet flow. This embodiment ensures that the pressure losses in the metering unit are reduced to a minimum value. In this case, the Zumessauslass can be formed as an annular space around the metering unit, whereby possible losses are reduced as much as possible.

In development of the invention the Zumessauslass is connected via a suction valve on a direct route to the pump working space. This embodiment also reduces the pressure loss and achieves better filling of the pump working space with fuel.

Further advantageous embodiments of the invention can be found in the drawing description in which an embodiment of the invention shown in the figures is described in more detail.

Brief description of the drawings

Show it:

Fig. 1 is a schematic circuit diagram of a fuel injection device with

High pressure pump,

2 is a detailed sectional view of Figure 1 of the pump interior directly connected to the metering unit flow connection,

3 shows a side view of a pump housing with an illustration of an inlet and a drain for fuel in the pump interior, a receiving recess for a metering unit and a bore for connecting the receiving recess to the pump interior, and FIG

, 4 is a plan view of the high-pressure pump according to FIG. 3. Embodiment of the invention

As shown in FIG. 1, a common rail fuel injection device for an internal combustion engine to a fuel tank 1, is sucked from the fuel by an electric fuel pump see 2 and is passed through a filter 3 and an inlet 4 in the pump interior 5 of a high-pressure pump. The high-pressure pump has a pump housing 6 enclosing the pump interior 5, in which a pump camshaft 7 is rotatably mounted. Cams 8a, 8b of the pump camshaft 7 are arranged in the pump interior 5 and cooperate with roller tappets 9 of two high-pressure pump elements 10. The high-pressure pump elements 10 each have a cooperating with the roller tappet 9 pump plunger, which is moved in a rotational movement of the pump camshaft 7 translationally up and down. The respective pump plunger defines a pump working space 11 to which fuel is supplied via a metering unit 12 and a suction valve 24 shown in FIG. The fuel is supplied to the metering unit 12 from the pump interior 5 via a filter, wherein the supply in the illustration of FIG. 1 for drawing technical reasons is not done directly. Parallel to the metering unit, an overflow valve 13 is also connected via a filter to the pump interior 5, via which fuel not forwarded by the metering unit 12 into the pump working spaces 11 is returned to the fuel tank 1 through a return line. This return line is further connected to a housing bearing 14 and a flange bearing 15 of the high-pressure pump, wherein the housing bearing 14 and the flange bearing 15 represent the storage of the pump camshaft 7. The housing bearing 14 and the flange bearing 15 are fuel lubricated, with the amount of fuel necessary for lubrication after the flow through the housing bearing

14 and the flange valve 15 is derived in the return line.

The two pump work chambers 11 are connected via check valves 16 to a high pressure accumulator 17, in which the fuel is fed under a pressure of about 3,000 bar. The high-pressure accumulator 17 is connected to a pressure control valve 8, via which the pressure in the high-pressure accumulator 17 is maintained at a permissible maximum pressure. The high-pressure accumulator 17 is connected to fuel injectors 19 corresponding to the number of cylinders of the internal combustion engine, wherein the fuel! injectors 19 controlled to inject fuel into the working chambers of the internal combustion engine.

Fig. 2 shows in addition to the parts taken from Fig. 1 components, the direct flow connection between the pump interior 5 and an inlet 20 in the Metering unit 12 by a recessed into the pump housing 6 bore 21, which is shown in this figure for drawing technical reasons as an external channel. The bore 21 produces an axial flow of the inlet 20 of the metering unit 12, wherein the axial flow is deflected by a metering valve 22 of the metering unit 12 in a radial outflow through a Zumessauslass 23. The metering outlet 23 can be formed by a plurality of openings in the metering unit 12, wherein the openings open into an annular space surrounding the metering unit 12 in this area, which in turn are connected directly to the suction valves 24 of the high-pressure pump elements 10 or their pump working spaces 11 ,

Figures 3 and 4 show in two views the pump housing 6 in the unmounted state, wherein the inlet 4 and a drain 26 for fuel in the pump interior 5 is shown. Furthermore, a receiving recess 25 for mounting the metering unit 12 is shown, wherein the receiving recess 25 is connected via a arranged in extension of the receiving recess 25 bore 21 with the pump interior 5. Furthermore, the sequence 26 is connected to the arranged in the interior of the high pressure pump spill valve 13, while outside the pump housing 6, the external return line is connected to the tank 1. In particular, in the plan view of Fig. 4, the exact position of the inlet 4, the drain 26, the receiving recess 25 and the receiving recess 25 with the pump interior 5 connecting bore 21 can be seen. Furthermore, a Wnkel of 90 ° enclosing receiving openings 27 for the two high-pressure pump elements 10 can be seen.

Claims

claims A high-pressure pump for a fuel injection device of an internal combustion engine, comprising a pump housing (6) with a pump interior (5) into which a feed (4) opens for fuel, and a metering unit (12) for metering fuel into a pump working space (11), wherein the metering unit (12) is connected to the pump interior (5),  characterized in that in the pump housing (6) is a pump interior (5) with the metering unit (12) directly connected flow connection is inserted. 2. High-pressure pump according to claim 1,  characterized in that the flow connection is a bore (21). 3. High-pressure pump according to claim 2,  characterized in that the bore (21) connects the pump interior (5) with an inlet (20) directly into the metering unit (12). 4. High-pressure pump according to claim 2 or 3,  characterized in that the bore (21) is arranged in extension of a receiving recess (25) for the metering unit (12). 5. High-pressure pump according to one of claims 2 to 4,  characterized in that the diameter of the bore (21) at least approximately corresponds to the diameter of the inlet (20) in the metering unit (12). 6. High-pressure pump according to one of claims 2 to 5,  characterized in that the bore (21) opens axially into the inlet (20) of the metering unit (12). High-pressure pump according to one of claims 2 to 6, characterized in that the inlet (20) of the metering unit (12) via a metering valve (22) with a Zumessauslass (23) is connected and that the axial inlet flow is deflected into a radial outlet flow. 8. High-pressure pump according to one of claims 2 to 7,  characterized in that the Zumessauslass (23) via a suction valve (24) on a direct path with the pump working space (1 1) is connected.