Fuel injection pump

Abstract

The present invention relates to a fuel injection pump for internal combustion engines, having a pump housing, in which a feed device is accommodated, whose operation is controlled with the aid of a control unit that is accommodated in a control-unit housing mounted to the pump housing.

Description

BACKGROUND INFORMATION

[0001] The present invention relates to a fuel injection pump for internal combustion engines, having a pump housing, in which a feed device is accommodated, whose operation is controlled with the aid of a control unit that is accommodated in a control-unit housing mounted to the pump housing.

[0002] Such an injection pump is known from DE OS 34 03 073 A1. In the known injection pump, the fuel to be delivered is directed through the control-unit housing for cooling purposes. Practical use has shown the heating of electrical components in the control-unit housing to be problematic.

[0003] The object of the present invention is to ensure sufficient cooling of the control-unit housing, without fuel flowing around electronic components contained in the interior of the control-unit housing.

[0004] This object is achieved by a fuel injection pump for internal combustion engines, having a pump housing, in which a feed device is accommodated, whose operation is controlled with the aid of a control unit that is accommodated in a control-unit housing mounted to the pump housing; in that

[0005] a cavity, into which a fuel inlet empties and from which a connecting line to the feed device originates, is formed between the upper side of the pump housing and the lower side of the control-unit housing; and in that

[0006] a filler piece having at least one diverter channel is situated in the cavity, the delivered fuel being directed from the fuel inlet to the lower side of the control-unit housing, via the diverter channel.

SUMMARY OF THE INVENTION

[0007] In this manner, the lower side of the control-unit housing is continuously wetted with fuel during operation, which results in a considerably improved cooling effect.

[0008] A particular embodiment of the present invention is characterized in that a mask is formed on the filler piece, the mask surrounding the fuel inlet in the pump housing when the filler piece is installed. The mask ensures that the fuel from the fuel inlet reaches the diverter channel. The mask prevents the fuel from taking a direct, short-circuit-flow path from the fuel inlet to the connecting line.

[0009] Another particular embodiment of the present invention is characterized in that the diverter channel starts out from a tab, which is formed on the filler piece and, in the installed state of the filler piece, is accommodated in a pocket that is taken out in the pump housing, in the region of the fuel inlet. This first of all improves the effect of the mask. Secondly, the tabs received in the pockets are used to hold the filler piece in position, in the installed state.

[0010] Another particular embodiment of the present invention is characterized in that an inlet tulip is formed in the upper surface of the filler piece facing the control-unit housing, the inlet tulip being connected to the connecting line in the pump housing, when the filler piece is installed. The inlet tulip acts as a funnel and ensures that the fuel is sucked in from above, and that the formation of air bubbles is prevented. Air still present in the cavity is dispersed in very small units in the aspirated fuel, using the filler piece of the present invention.

[0011] A further, particular embodiment of the present invention is characterized in that all of the fuel channels provided in the filler piece are designed to have a low resistance to flow. This ensures that the pressure drop across the filler piece is kept as low as possible.

[0012] Another particular embodiment of the present invention is characterized in that the inlet of the connecting line in the pump housing is funnel-shaped. This keeps the pressure drop low.

[0013] Another particular embodiment of the present invention is characterized in that two diverter channels are provided on opposite sides of the filler piece. This has the advantage of the filler piece being able to be attached on two opposite sides of the pump housing.

[0014] A further particular embodiment of the present invention is characterized in that, a plurality of chambers open from below are formed in the filler-piece surface that faces the pump housing in the installed state of the filler piece. The subdivision of the lower side of the filler piece into several chambers reduces the volume of air possibly trapped in the cavity to a safe value.

[0015] Additional advantages, features, and details of the present invention result from the subsequent description, in which an exemplary embodiment of the present invention is explained in detail with reference to the drawing. In this context, the features mentioned in the claims and the Specification may each be essential to the present invention, either alone or in arbitrary combination.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The figures in the drawing show:

[0017] FIG. 1 a perspective view of a filler piece according to the present invention;

[0018] FIG. 2 a rear view of the filler piece from FIG. 1; and

[0019] FIG. 3 a bottom view of the filler piece from FIG. 1.

[0020] The filler piece shown in perspective in FIG. 1 is accommodated in a cavity, which is formed between the upper side of the pump housing and the lower side of the control-unit housing of an injection pump according to the present invention. Emptying into the cavity is a fuel inlet, through which fuel from a fuel tank reaches the cavity. The fuel may either be transported in the cavity with the aid of a presupply pump, or drawn in by the feed pump of the injection pump alone. A connecting line leads from the cavity to the feed device of the injection pump. The opening for the connecting line is situated in the cavity, above the opening for the fuel inlet. This causes the cavity to constantly be filled with fuel to a certain level. In addition, a certain amount of air in the cavity cannot be avoided during operation. The cavity is delimited from below by the pump housing of the injection pump. The cavity is delimited-from above by the lower side of a control-unit housing. The control-unit housing is used to accommodate electronic components, which heat up during operation.

[0021] In the installed state, the filler piece represented in FIG. 1 is accommodated in the cavity in such a manner, that its upper side 1 is turned towards the lower side of the control-unit housing. As a rule, upper side 1 of the filler piece is horizontally positioned, in the installed state. Eight planar side faces 2 through 9 extend in an essentially vertical direction, from upper side 1 of the filler piece. A diverter channel 11 is removed from planar side face 9 of the filler piece. A diverter channel 12 is removed from planar side face 5 of the filler piece. Diverter channel 11 extends from a tab 13, which is used to position the filler piece, to upper side 1 of the filler piece. Diverter channel 12 likewise extends from a tab 14 to upper side 1 of the filler piece. A mask 15, which, in the installed state, surrounds the intake port of the fuel inlet in the cavity, is formed on tab 13. A corresponding mask is formed on tab 14. The fuel entering into the cavity is directed through diverter channels 11 and 12, to upper side 1 of the filler piece. In this manner, it is ensured that the lower side of the control-unit housing is wetted with fuel. The positioning of the diverter channel is selected so that a certain mass flow rate of fuel strikes the control-unit surface, over which the electronic module having the greatest heat loss is situated. The heat is dissipated, using correction.

[0022] An inlet tulip 18 is formed in the center of upper side 1 of the filler piece. Inlet tulip 18 is connected to fuel outlet 20 via connecting tube 19. In the installed state of the filler piece, fuel outlet 20 is situated near the inlet of the connecting line leading to the feed device of the injection pump. Fuel outlet 20 is situated on a beveled surface 21 of the filler piece. The positioning of the inlet tulip on the top allows the air accumulated on top to be continuously removed and thus ensures that the lower side of the control-unit housing remains wetted with fuel. The funnel-shaped design of the inlet tulip also produces a lower resistance to the flow of fuel.

[0023] Two guide pins 25 and 26, which are slotted on the end, project outwards from the lower side of the filler piece. In the installed state, guide pins 25 and 26 are used to lock the filler piece in position in the cavity.

[0024] In the bottom view represented in FIG. 3, one can see that the filler piece is subdivided into several block-shaped chambers 30, 31, which are open from below. Chambers 30, 31 are formed by vertical partitions, which are positioned perpendicularly to each other.

[0025] The filler piece of the present invention ensures that the fuel is directed on, between the pump housing and the control-unit housing. This minimizes the pressure drop. In addition, the filler-piece design according to the present invention ensures that air is continuously exhausted from the cavity.

[0026] In the installed state of the filler piece, fuel flows from the fuel inlet into the space formed between the lower side of the control-unit housing and the upper side of the filler piece. The cooling action of the fuel takes place in this space. The fuel travels from the space, through inlet tulip 18 and connecting tube 19, to the connecting line (not shown) leading to the feed device of the injection pump. The design of the filler piece of the present invention to allow the fuel to be drawn off through the highest point, using an inlet tulip, or to be at least drawn off through the inlet tulip, or to only drain off through the inlet tulip, ensures that the cavity is at least filled up to upper side 1 of the filler piece.

Claims

1. A fuel injection pump for internal combustion engines, having a pump housing, in which a feed device is accommodated, whose operation is controlled with the aid of a control unit that is accommodated in a control-unit housing mounted to the pump housing, wherein a cavity, into which a fuel inlet empties and from which a connecting line leading to the feed device originates, is formed between the upper side of the pump housing and the lower side of the control-unit housing; and a filler piece having at least one diverter channel (11) is situated in the cavity, the delivered fuel being directed from the fuel inlet, through the diverter channel, to the lower side of the control-unit housing.

2. The fuel injection pump as recited in claim 1, wherein a mask 15, which surrounds the fuel inlet in the pump housing when the filler piece is installed, is formed on the filler piece.

3. The fuel-injection pump as recited in one of the preceding claims, wherein the diverter channel (11) originates at a tab (13), which is formed on the filler piece and, in the installed state of the filler piece, is accommodated in a pocket that is taken out in the pump housing, in the region of the fuel inlet.

4. The fuel injection pump as recited in one of the preceding claims, wherein an inlet tulip (18) is formed in the upper surface (1) of the filler piece facing the control-unit housing, the inlet tulip being connected to the connecting line in the pump housing, when the filler piece is installed.

5. The fuel-injection pump as recited in one of the preceding claims, wherein all of the fuel channels (11, 12, 19) provided in the filler piece are designed to have a low resistance to flow.

6. The fuel-injection pump as recited in one of the preceding claims, wherein the inlet of the connecting line in the pump housing is formed in the shape of a funnel.

7. The fuel-injection pump as recited in one of the preceding claims, wherein two diverter channels (11, 12) are provided on opposite sides of the filler piece.

8. The fuel-injection pump as recited in one of the preceding claims, wherein, in the installed state of the filler piece, a plurality of chambers (30, 31) open in the downward direction are formed in the filler-piece surface that faces the pump housing.