1. Field of the Invention
The invention is directed to an improved geared feed pump particularly useful in conjunction with a fuel injection system of an internal combustion engine.
2. Description of the Prior Art
One geared feed pump of the type with which this invention is concerned is known from German Patent Disclosure DE 19638332 A1. This geared feed pump has a housing in which a pump chamber is formed, in which chamber a rotationally driven pair of gear wheels meshing with one another is disposed, which gear wheels pump a pumping medium out of a suction chamber that communicates with a supply tank, along feed conduits, formed between the circumferential surface of the gear wheels and the circumferential walls of the pump chamber, into a pressure chamber. The geared feed pump furthermore has a drive shaft, which is connected in a rotationally engaged manner with one of the gear wheels via a coupling member disposed inside the housing in a coupling chamber. The coupling member has no lubrication and under some circumstances is therefore subject to severe wear.
The geared feed pump of the invention has the advantage over the prior art that lubrication of the coupling member is accomplished by the pumping medium, and wear is thus reduced.
Various embodiments and advantageous features and refinements of the geared feed pump of the invention are disclosed. One embodiment assures that only a slight portion of the quantity pumped by the geared feed pump is diverted to the coupling chamber for lubrication. Another refinement assures that the quantity pumped by the geared feed pump is not reduced when the pumping is started, and that none of the pumped quantity is diverted into the coupling chamber for lubrication until an adequate pumping pressure is achieved. Other embodiments make a simple embodiment of the pressure valve possible.
Three exemplary embodiments of the invention are described in further detail in the ensuing description, taken in conjunction with the drawings, in which:
A geared feed pump shown in
The geared feed pump moreover has a drive shaft 30, which is rotatably supported in the housing part 10 and/or in the cap part 12. The drive shaft 30 is disposed at least approximately coaxially to the bearing journal 24, and the bearing journal 24 has a blind bore 32 into which the end of the drive shaft 30 protrudes. The cap part 12 has a bore 34 through which the drive shaft 30 passes, and a shaft sealing ring 36 is built in between the bore 34 and the drive shaft 30 in order to seal off the housing. A sealing ring 38 is also built in between the housing part 10 and the cap part 12.
The bearing journal 24 ends with an axial spacing from the cap part 12, and a coupling member 40 disposed between the face end of the bearing journal 24 and the cap part 12 is joined to the drive shaft 30. The coupling member 40 is connected by positive engagement in the direction of rotation to the drive shaft 30. The connection of the coupling member 40 to the drive shaft 30 can be made for instance by means of a non-circular cross section of the drive shaft 30, which can be accomplished for instance by means of one or more flat faces on the circumference of the drive shaft 30. The coupling member 40 has an opening with a correspondingly shaped cross section. In the gear wheel 16, which is supported on the bearing journal 24, its bore 17 is embodied in the axial direction approximately at the revel of the bearing journal 24. Toward its side toward the cap part 12, the gear wheel 16 has an opening 42, which is embodied as noncircular in cross section and which is engaged by the coupling member 40. The outside cross section of the coupling member 40 and the inside cross section of the opening 42 are complementary to one another in such a way that there is a connection in a rotationally engaged manner between the coupling member 40 and the gear wheel 16. For example, the cross sections of the coupling member 40 and of the opening 42 may be polygonal, or they may have radial protrusions and corresponding radial recesses that are engaged by the protrusions. The region in the axial extension between the bearing journal 24 and the cap part 12, in which cap part the coupling member 40 is disposed, forms a coupling chamber 41 which communicates with the blind bore 32.
In operation of the geared feed pump, the gear wheel 16 is driven to rotate via the drive shaft 30 and transmits this rotary motion, via a spur gear, to the gear wheel 18 which meshes with the gear wheel 16 and is likewise provided with a spur gear. The gear wheels 16, 18, by the meshing of their teeth, divide the pump chamber 14 into two portions, of which a first portion forms a suction chamber 44 and a second portion forms a pressure chamber 46. The suction chamber 44 communicates with the pressure chamber 46 via one feed conduit 48 each, formed between the tooth slots on the circumferential surfaces of the gear wheels 16, 18 and the upper and lower circumferential walls of the pump chamber 14. The suction chamber 44 and the pressure chamber 46 each have one connection opening in the wall of the housing part 10 or of the cap part 12, by way of which opening the suction chamber 44 communicates with a suction line, not shown, from the supply tank, and the pressure chamber 46 communicates, via a feed line, also not shown, with the suction chamber of the fuel injection pump. The connection opening into the suction chamber 44 forms an inlet opening 50, and the connection opening into the pressure chamber 46 forms an outlet opening 52.
In
The geared feed pump of the invention functions as follows. In operation of the geared feed pump, the drive shaft 30 is driven preferably in proportion to the rpm of the internal combustion engine to be supplied. The drive shaft 30 transmits the rotary motion via the coupling member 40 to the gear wheel 16, which in turn drives the gear wheel 18 meshing with it to rotate. As a result of the rotary motion of the meshing gear wheels 16, 18, the fuel is pumped out of the suction chamber 44 along the feed conduits 48 into the pressure chamber 46. This creates a negative pressure in the suction chamber 44 that is sufficient to aspirate further fuel from the supply tank via the suction line. The fuel pressure built up in the pressure chamber 46 brings about fuel pumping via the outlet opening 52 into the supply line to the fuel injection pump.
From the pressure chamber 46, fuel under pressure flows through the bore segments 54, 56 into the blind bore 32 and from it into the coupling chamber 41. By means of the fuel, lubrication of the coupling member 40 in the coupling chamber 41 is attained; both the contact points between the coupling member 40 and the drive shaft 30 and the contact points between the coupling member 40 and the gear wheel 16 are lubricated. Diesel fuel has a viscosity that enables lubrication. The throttle restriction 58 into the bore segment 54, 56, or their embodiment with a small cross section, assures that only a slight quantity of fuel for lubrication is diverted from the pressure chamber 46 into the coupling chamber 41, correspondingly reducing the pumping quantity of the geared pump. The coupling chamber 41 can additionally have a connection with the suction chamber 44, through which connection fuel can flow out of the coupling chamber 41 back into the suction chamber 44.
In
In
The foregoing relates to preferred exemplary embodiment of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.
This application is a 35 USC 371 application of PCT/DE 01/01166 filed on Mar. 27, 2001.
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/DE01/01166 | 3/27/2001 | WO | 00 | 6/2/2003 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO02/07746 | 10/3/2002 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
3063378 | Hart | Nov 1962 | A |
3170409 | McLeod et al. | Feb 1965 | A |
3306225 | Smith | Feb 1967 | A |
4501536 | Middlekauff | Feb 1985 | A |
4770617 | Hertell | Sep 1988 | A |
5167496 | Jacobsson et al. | Dec 1992 | A |
6071105 | Bodzak et al. | Jun 2000 | A |
6123531 | Blume et al. | Sep 2000 | A |
Number | Date | Country |
---|---|---|
196 38 332 | Mar 1998 | DE |
199 422 221 | Mar 2001 | DE |
2 056 567 | Mar 1981 | GB |
09-4570 | Jul 1997 | JP |
Number | Date | Country | |
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20030180160 A1 | Sep 2003 | US |