EP1310672B1 - Fuel pump for a fuel system of an internal combustion engine and fuel system - Google Patents

Description

The invention initially relates to a fuel pump device for a fuel system of an internal combustion engine, in particular with direct injection, with a fuel pump and a drive motor connected thereto.

Such a fuel pump device known from EP 0 725 212 A2. In this, a fuel system is described in which a first fuel pump device promotes fuel from a fuel tank to a second fuel pumping device and from there via a high-pressure region to injectors. Both fuel pumping devices each comprise a fuel pump and an electric drive motor connected to the fuel pump. The delivery rate of both fuel pumping devices can be changed and adjusted via the rotational speed of the electric drive motor. The non-prepublished DE 101 11 837 A1 discloses an axial piston pump and an electric drive motor, which are housed in an outwardly sealed housing.

The disadvantage of the known fuel pumping device is that its handling and integration into the fuel system is difficult and therefore makes the structure of the fuel system expensive. Also, the pump power does not correspond to the operating points of the Internal combustion engine meets the requirements.

It is therefore an object of the present invention to develop a fuel pump device of the type mentioned so that it is easier to build and that the corresponding fuel system can be manufactured inexpensively. It should also be able to provide the high injection pressure, in particular in internal combustion engines with direct injection, at all operating points of the internal combustion engine.

This object is achieved in a fuel pump device of the type mentioned above in that the fuel pump is a radial piston pump and the drive motor and the fuel pump form a unit with a common fluid-tight housing.

The design of the fuel pump as a radial piston pump allows the generation of high pressures, as required in modern fuel systems for internal combustion engines with gasoline direct injection. The fact that the drive motor and the fuel pump form a unit, handling in the construction of the fuel system is greatly facilitated. Thus, the unit consisting of the drive motor and the fuel pump can be preassembled, so that in the construction of the fuel system, for example in a motor vehicle, only one common part and not two separate parts are to be handled.

The accommodation of the drive motor and the fuel pump in a common fluid-tight housing further improves the handling of the thus designed fuel pump device. In this case, such a fluid-tight housing is already required for the fuel pump so that this does not or hardly leads to additional costs. By also the drive motor in the fluid-tight housing, it is ensured that the drive motor is protected against contamination from the outside. Thus, less pollution-tolerant, but powerful electric motors can be used, which once again benefits the performance of the fuel pumping device. The service life of the fuel pump device is improved by this measure.

The efficiency of the fuel pump device according to the invention is also improved by the fact that the otherwise required shaft seal can be omitted from the fuel pump to the drive motor. Such a shaft seal is always associated with some friction and leakage, both of which reduce the efficiency of the fuel pump. The omission of the shaft seal also reduces costs.

Advantageous developments of the fuel pump device according to the invention are specified in subclaims.

For example, it is proposed that the fuel pump comprises a drive shaft with at least one bearing, which is at the same time a rotor shaft of the drive motor. Such a designed fuel pump device is very compact, since it is dispensed with separate waves on the one hand for the fuel pump and on the other hand for the drive motor. Also, less bearings are required for storage of the drive shaft or the rotor shaft, resulting in smaller dimensions and lower production costs of the fuel pump device.

It is particularly preferred if a, preferably fluid-tight, cover is present, through which the Warehouse is protected from particles coming from the drive motor. As a result, the life of the bearing is increased and the camp must be designed to be less robust overall, which again reduces the overall dimensions and costs of the fuel pump device.

In a particularly preferred embodiment of the fuel pump device according to the invention, the interior of the housing of the unit formed by the fuel pump and the drive motor is flowed through by the fuel at least in the region of the drive motor. This has the advantage that the drive motor is cooled by the fuel, which improves its efficiency.

It is particularly preferred if the flow guide is formed in the interior of the housing of the unit formed from the fuel pump and the drive motor so that the fuel first flows through the drive motor at least partially and then passes to the fuel pump, and that in the flow path between the drive motor and fuel pump, a filter device , in particular a sieve, is present.

In this fuel pump device, the drive motor is optimally cooled, which has an advantageous effect on its efficiency and what overall improves the delivery rate of the fuel pump device. This prevents blockages in the flow channels of the fuel pump or at their valve devices. These could be caused by parts which detach, for example, from the magnets of the drive motor made of a brittle material. In this development of the fuel pump device according to the invention, the high efficiency is thus present over the entire service life of the device.

Also particularly compact builds that development in which the drive shaft of the fuel pump has an Exzenderabschnitt and arranged around the Exzenderabschnitt around cam ring and for each piston connected to the piston and the cam ring abutting slide, wherein in the radially outer peripheral surface of the cam ring circumferential groove and in the shoe and in the piston, a radially extending channel are present. The groove and the channels can be introduced in a simple and inexpensive manner. Through the groove and the channels of the fuel can be performed with less flow resistance. The introduction of complex holes, for example, in a cylinder head of the radial piston pump thus eliminated. As a result, the costs are additionally kept low.

In the same direction aims that fuel pumping device in which the fuel pump comprises a suction valve disposed in the piston. This measure also reduces the dimensions of the fuel pumping device and the cost of their manufacture.

It is also proposed that at least the valve element of the suction valve is made of a ceramic material. Such a ceramic valve element builds relatively easily, which has advantages in terms of valve dynamics. Further, such a valve element is insensitive to wear, so that the life of the thus configured fuel pumping device is high.

In a further particularly preferred embodiment of the fuel pump device according to the invention, this comprises an electronic control part, which controls the drive motor, with a control part housing which on the housing of the fuel pump and the drive motor formed unit is attached with at least one fastening means. An electronic control is required for most types of drive motors anyway to provide the required signals for the drive in the desired manner. The fact that the electronics are housed in a separate control part, it can be optimally pre-assembled. In particular, in the pre-assembly such mounting conditions can be met, which are required for the correct functioning of the control electronics. Subsequently, the control part housing of the control part can be fixed to the housing of the unit formed by the fuel pump and the drive motor. If this occurs before the engine is mounted on it, the assembly work on the internal combustion engine is simplified.

In this case, it is again preferred for the fastening means to penetrate the wall of the housing of the unit formed by the fuel pump and the drive motor, and for the fastening means to be sealed off from the housing of the unit formed by the fuel pump and the drive motor by a sealing means. Characterized in that the fastening means penetrates the wall of the housing of the unit formed from the fuel pump and the drive motor, a particularly secure and stable attachment of the control part housing is made possible. At the same time, the sealing means provided according to the invention ensures that fuel which is present in the housing can not escape from it to the control part.

In this case, it is further preferred if electrical lines, which lead from the control part to the drive motor, are connected to the fastening means. The connection of the control electronics with the drive motor is easily possible in this way. In this case, the lines, for example be cast in the fastener or welded or soldered to this, so that the tightness between the control part housing and the housing of the drive motor and the fuel pump is ensured.

Furthermore, it is advantageous if the fastening means, preferably between the control part housing and the housing of the unit formed by the fuel pump and the drive motor, a degassing channel leads to the outside. This ensures that, when fuel gases, which pass the sealant past or through it from the interior of the housing of the drive motor and the fuel pump to the outside, kept away from the sensitive control electronics and be discharged into the environment instead.

The assembly of the fuel pump device is further simplified in that the housing of the unit formed by the fuel pump and the drive motor comprises at least two parts which are fluid-tightly interconnected, wherein on the one hand the fuel pump and a rotor connected to the drive shaft and the other Part of the stator belongs. Both parts can thus be pre-assembled independently in possibly different production facilities. The final assembly is still very simple.

The invention also relates to a fuel system for a direct injection internal combustion engine having a first fuel pump which delivers fuel to a fuel pumping device comprising a second fuel pump and an electric drive motor connected thereto and a high pressure region into which the second fuel pump delivers and is connected to the at least one fuel injection device.

In order to simplify the structure of the fuel system, to make the assembly of the components of the fuel system safer and cheaper and to increase the performance of the fuel system, it is proposed that the second fuel pump is a radial piston pump and the drive motor and the second fuel pump unit with a common fluid-tight Form housing.

drawing

Figur 1

eine schematische Darstellung eines Kraftstoffsystems einer Brennkraftmaschine mit Direkteinspritzung, welche eine KraftstoffPumpeinrichtung umfasst; und

Figur 2

eine teilweise geschnittene Darstellung durch die Kraftstoff-Pumpeinrichtung von Figur 1.

Hereinafter, a particularly preferred embodiment of the invention with reference to the accompanying drawings will be explained in detail. In the drawing show:

FIG. 1

a schematic representation of a fuel system of a direct injection internal combustion engine, which comprises a fuel pumping device; and

FIG. 2

a partially sectioned view through the fuel pumping device of Figure 1.

Description of the embodiment

In FIG. 1, a fuel system for an internal combustion engine as a whole carries the reference numeral 10. The internal combustion engine is shown only in part in FIG. 1 and bears the reference numeral 12.

The fuel system 10 includes a fuel tank 14 from which a fuel pump 16 delivers the fuel. This is driven by an electric drive motor 18. The fuel pump 16 conveys the fuel through a filter 19 to a fuel pumping device 20. This includes a housing 22 in which an electric Drive motor 24 and a radial piston pump 26 are housed. On the housing 22, an electronic control part 28 is attached. The detailed structure of the fuel pumping device 20 will be discussed in detail below.

The fuel pumping device 20 delivers the fuel under very high pressure into a fuel rail 30 ("rail") associated with a high-pressure region in which the fuel is stored under very high pressure. To this several fuel injectors 32 are connected. These inject the fuel directly into corresponding combustion chambers 34 of the internal combustion engine 12. The pressure in the fuel rail 30 is detected by a pressure sensor 36. It supplies corresponding signals to a control and regulating device 38. From this, in turn, control lines lead to the electronic control part 28 of the fuel pump device 20 and to the electric drive motor 18, which drives the fuel pump 16.

The fuel pump device 20 is constructed as follows (Figure 2): The housing 22 is in two parts with a left in Figure 2 part 40 and a right in Figure 2 part 42. The left housing part 40 is executed block-like and has substantially circular cylindrical, disc-like Shape. Coaxial with its longitudinal axis 44, a blind hole 45 is introduced from the right into the left housing part 40 in FIG. In this open several, distributed over the circumference, radially extending and outwardly open blind holes 46. In these are the cylinders of the radial piston pump 26. In the sectional plane of Figure 2, only such a cylinder is visible. The blind holes 46 running in the radial direction are in each case fluidically connected to the electric drive motor 24 through an opening 47. In the openings 47 a strainer insert 49 is present in each case.

In the blind hole 45, two roller bearings 48 and 50 are used, through which a drive shaft 52 relative to the left housing part 40 is mounted friction. At the stationary part of the right rolling bearing 50, a cover ring 53 is attached to the electric drive motor 24. By this, the rolling bearing 50 is protected from particles which may result from the electric drive motor 24 during operation. The drive shaft 52 has an eccentric portion 54 lying in the installed position at the level of the blind hole 46. In turn, a lifting ring 56 is placed on these. In the region of a cylinder, the outer circumferential surface of the cam ring 56 is flattened in each case.

In the radially extending blind hole 46 of a cylinder, a bushing 58 is inserted. In this turn, a piston 60 is slidably received in the radial direction. At the radially inner end of the piston 60, a shoe 62 is attached. This is acted upon by a compression spring 64, which is supported on the bushing 58, against the cam ring 56. In the outer, partially flattened lateral surface of the cam ring 56, a continuous groove 66 is present. With this is a bore 68 in the shoe 62 and a coaxially extending in the piston 60 bore 70 in connection.

The bore 70 in the piston 60 has a larger diameter in its radially outer region than in the radially inner region. In the transition between these two areas an oblique transition surface (without reference numeral) is present, which forms a valve seat for a valve ball 72 of a suction valve 74. The valve ball 72 is made of a ceramic material and is acted upon by a compression spring (no reference numeral) against the valve seat. Between the piston 60 and the blind hole 46 radially outwardly closing cylinder head 76, a working space 78 is present. About as a flat seat valve trained pressure valve 80, the working space 78 can be connected to an outlet channel 82 present in the left housing part 40. This leads to the fuel manifold 30th

The drive shaft 52 of the radial piston pump 26 is in Figure 2 to the right over the interface of the left housing part 40 and forms here a rotor shaft 84 of a rotor 86 of the electric drive motor 24. The rotor 86 is fixed to the rotor shaft 84 by a screw 88 and opposite this secured against rotation by a locking disc 90. The rotor 86 has a cup shape. On its radially outer surface magnets 92 are applied.

The right housing part 42 is also cup-shaped. It is sealed relative to the left housing part 40 via an O-ring 93. Windings 94 of the drive motor 24 are attached to its radially inner circumferential surface. The interior of the right housing part 42 is connected via an inlet, not shown, with the first fuel pump 16.

In Figure 2 right of the right housing part 42 is the electrical control part 28. This includes a housing 96 in which electronic components 98 are housed, which are required for the control of the windings 94 of the electric drive motor 24 of the radial piston pump 26. The electronic components 98 are in turn driven by the control and regulating device 38. The control part housing 96 is fixed to the right housing part 42 by a bolt 100. This is guided in two sleeves 102 and 104, between which an O-ring 106 is pressed in the installed position. The length of the sleeves 102 and 104 is chosen so that the O-ring 106 is still in the region of the right housing part 42. The interior of the right housing part 42 is thus fluid-tight completed.

In the bolt 100, power lines 108 are routed from the windings 94 to the electronic components 98. The power lines 108 are possibly welded or soldered to the bolt 100. Between the control part housing 96 and the right housing part 42 leads from the bolt 100 in the form of a groove outside on the housing part 42 a degassing channel 110 radially outward. As a result of this, gases which pass from the right-hand housing part 42 through the O-ring 106 are kept away from the electronic components 98 and discharged radially outward.

In operation, the fuel from the first fuel pump 16 is compressed to approximately 4 to 6 bar. He passes with this pressure in the interior of the right housing part 42. About the electronic components of the electric drive motor 18 is offset by the control and regulating unit 38 in rotation, whereby the drive shaft 52 in a rotary motion, the cam ring 56 in a circumferential stroke and the Pistons 60 are placed in a reciprocating motion. The fuel flows through the interior of the right housing part 42, thereby cooling the components of the drive motor 24 and those of the power electronics 98, and then passes through the openings 47, the groove 66 in the cam 56, and the bores 68 and 70 in the shoe 62 and in the Piston 60 in the working space 78. By the sieves 49 in the openings 47 contamination are kept away from the working space 78. From the working space 78, the fuel continues to flow via the outlet channel 82 to the fuel manifold 30.

The fuel pump device 20 is mounted as follows: First, the left housing part 40 is pre-assembled with the components of the radial piston pump 26. The rotor 86 of the electric drive motor 24 is already mounted on the rotor shaft 84. At the same time, if necessary, in another assembly plant, the right housing part 42 can be pre-assembled with the windings 94. The assembly of the control sub-housing 96 and the connection of the windings 94 with the electronic components 98 in the control sub-housing 96 is possible here.

Then the final assembly takes place, in which the right housing part 42 is pushed with the windings 94 on the rotor 86 and attached to the left housing part 40. In this way, an integral and compact unit, which comprises the radial piston pump 26 for generating very high delivery pressures, the associated electric drive motor 24 for generating high speeds, and the electrical control part 28 for controlling the electric drive motor 24.

Claims (14)

1. Fuel pumping device (20) for a fuel system (10) of an internal combustion engine (12), in particular with direct injection, with a fuel pump (26) and an electric drive motor (24) connected to the latter, characterized in that the fuel pump is a radial piston pump (26), and the drive motor (24) and the fuel pump (26) form a unit with a common fluid-tight housing (22).
2. Fuel pumping device (20) according to Claim 1, characterized in that the fuel pump (26) comprises a drive shaft (52) with at least one bearing (48, 50), the said drive shaft at the same time forming a rotor shaft (84) of the drive motor (24).
3. Fuel pumping device (20) according to Claim 2, characterized in that a preferably fluid-tight cover (53) is present, by means of which the bearing (50) is protected from particles which come from the drive motor (24).
4. Fuel pumping device (20) according to one of the preceding claims, characterized in that the fuel flows, at least in the region of the drive motor (24), through the inner space of the housing (24) of the unit formed from the fuel pump (26) and the drive motor (24).
5. Fuel pumping device (20) according to Claim 4,
   characterized in that the flow routing in the inner space of the housing (22) of the unit formed from the fuel pump (26) and the drive motor (24) is designed such that the fuel first flows through the drive motor (24), at least in regions, and then arrives at the fuel pump (26), and in that a filter device, in particular a sieve (49), is present in the flow path between the drive motor (24) and fuel pump (26).
6. Fuel pumping device (20) according to one of the preceding claims, characterized in that the drive shaft (52) of the fuel pump (26) has an eccentric portion (54), and a stroke ring (56) arranged around the eccentric portion (54) and, for each piston (60), a sliding shoe (62) connected to the piston (60) and bearing against the stroke ring (56) is present, a continuous groove (66) being present in the radially outer circumferential surface of the stroke ring (56), and a radially running duct (68, 70) being present in the sliding shoe (62) and in the piston (60).
7. Fuel pumping device (20) according to one of the preceding claims, characterized in that the fuel pump (26) comprises a suction valve (74) arranged in the piston (60).
8. Fuel pumping device (20) according to Claim 7, characterized in that at least the valve element (72) of the suction valve (74) is produced from a ceramic material.
9. Fuel pumping device (20) according to one of the preceding claims, characterized in that it comprises an electronic control part (28) which activates the drive motor (24), with a control-part housing (96) which is fastened by at least one fastening means (100) to the housing (22) of the unit formed from the fuel pump (26) and the drive motor (24).
10. Fuel pumping device (20) according to Claim 9, characterized in that the fastening means (100) penetrates the wall of the housing (22) of the unit formed from the fuel pump (26) and the drive motor (24), and in that the fastening means (100) is sealed off by a sealing means (106) with respect to the housing (22) of the unit formed from the fuel pump (26) and the drive motor (24).
11. Fuel pumping device (20) according to Claim 10, characterized in that electrical lines (108) which lead from the control part (28) to the drive motor (24) are connected to the fastening means (100).
12. Fuel pumping device (20) according to either one of Claims 10 and 11, characterized in that a degassing duct (110) leads outwards from the fastening means (100), preferably between the control-part housing (96) and the housing (22) of the unit formed from the fuel pump (26) and the drive motor (24).
13. Fuel pumping device (20) according to one of the preceding claims, characterized in that the housing (22) of the unit formed from the fuel pump (26) and the drive motor (24) comprises at least two parts (40, 42) which are connected to one another in a fluid-tight manner, the fuel pump (26) and a rotor (86) connected to the drive shaft (42) belonging to one part (40), and the stator (94) belonging to the other part (42).
14. Fuel system (10) for an internal combustion engine (12), in particular with direct injection, with a first fuel pump (16) which conveys fuel to a fuel pumping device (20) which comprises a second fuel pump (26) and an electric drive motor (24) connected to the latter, and with a high-pressure region (30) into which the second fuel pump (26) conveys and to which at least one fuel injection device (32) is connected, characterized in that the second fuel pump is a radial piston pump (26), and the drive motor (24) and the second fuel pump (26) form a unit with a common fluid-tight housing (22).

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