GB1598537A

GB1598537A - Feed pumps

Info

Publication number: GB1598537A
Application number: GB2514978A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1977-10-12
Filing date: 1978-05-31
Publication date: 1981-09-23
Also published as: DE2745800A1; JPS5464704A

Description

N (54) IMPROVEMENTS IN AND RELATING TO FEED PUMPS (71) We, ROBERT BOSCH GMBH, a German company of Postfach 50, 7 Stuttgart 1, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following state ment: This invention relates to a method for the feeding of fuel or other liquid under pressure and to a feed pump assembly.

Owing to the deteriorating fuel quality, functional disturbances increasingly occur during fuel feeding at elevated temperatures in the usual roller-vane type feed pumps. These can be prevented by supplying fuel under a slight pressure, whereby failure caused by an extreme increase of vapour formation can be avoided. The generation of the supply pressure can be assumed by a hydrodynamic pump with a degassing facility, which is either connected in series as a separate electric fuel pump or, as in the present invention, which is integrated as a preliminary stage into the region of a main pump stage.

Fuel feed pump assemblies which comprise a pumping system containing a preliminary feed pump and a main feed pump effectively connected in series and jointly driven by a common electric motor, have been proposed before. In the case of the integrated two-stage pump, where all the components are arranged in a common housing with the electric motor, the torque transmission from the motor rotor to the rotary parts of the individual pumping stages is of importance, since it is desirable that there should be no excessive mutual influencing of the individual pumping stages in their mobility. Moreover the necessarily good sealing of the pumping stages with re-spect to one another in the region of the support of the rotating parts, and thus a sealing between high pressure and intermediate pressure chamber, is also very important.

In accordance with this invention there is provided a method for feeding a liquid by means of a pumping system arranged in a common housing with an electric motor, the pumping system having a preliminary feed stage and a main feed stage, the rotary parts of which are both driven by the electric motor, in which method the liquid flowing to or from the preliminary feed stage, which directly adjoins the electric motor, flows through the electric motor, the region thereof thereby forming a suction chamber or an intermediate pressure chamber of the pumping system.

Also in accordance with this invention there is provided a feed pump assembly for a liquid, comprising a pumping system arranged in a common housing with a driving electric motor, the pumping system having a preliminary feed pump and a main feed pump, the two being hydraulically connected in series and their respective rotors being driven by the electric motor, the preliminary pump being arranged directly adjoining the electric motor so that the region of the electric motor constitutes a suction chamber or an intermediate pressure chamber of the pumping system, whereby liquid flowing to or from the preliminary feed pump flows through the electric motor.

The method and the feed pump assembly in accordance with the invention, overcome these difficulties and have an advantage over the known methods and assemblies in that, on rotary driving of the two rotary parts of the pumping stages, few difficulties arise.

This is because the pumping stages are mechanically separated, and because a pressuretight, positive connection, of the rotary part of the preliminary feed pump with the motor rotor, is possible resulting with very good sealing of the pump stages.

The invention is further described hereinafter, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a longitudinal section through a first embodiment of a fuel feed pump, in accordance with this invention, two pumping stages being combined in a common block; and, Figure 2 is a second embodiment of a fuel feed pump, in which the two pumping stages are arranged on either side of a driving electric motor.

The feed pump represented in the two figures of the drawing, comprises a pumping region, 1 or rather ib and la in the second embodiment, containing the two pumping stages and an electric motor 2 which drives the two pumping stages. The two pumping stages, namely a side channel pump 3, 3a chosen as a preliminary pump and a roller-vane pump 4, 4a operating as the main feed pump, together with the electric motor 2 are accommodated in a tubular housing 5. The housing is closed at one end by a cover 45 against which rests a radially inwardly extending circular flange 5a of the housing and at its other end by a cover 8 which is held by a flanging 6. There is thus achieved a compression on components arranged one after the other inside the housing.

It is understood, however, that the housing 5 could be pot-shaped and that the suction or pressure connections required could thereby be integral regions of the end walls of the housing. The assembly is provided on the righthand side in the plane of the drawing with a suction connection 7 onto which can be fitted a connection hose (not shown). The suction connection 7 is an integral part of the cover 8 retained by the flanging 6 which also supports the terminal connections 9a, 9b for the supply of electric energy to the electric motor. Inside the housing, in axial sequence from the suction side to the pressure side are thus arranged first the preliminary pump 3, 3a and then the main feed pump 4, 4a.The electric motor 2 is located either upstream of the two pumping stages which consequently form a common block, as shown in the embodiment of Figure 1, or it is arranged between the two pumping stages, as in Figure 2. In either case the fuel being pumped flows through its components, so that the motor is cooled.

The embodiments of Figure 1 and 2 also have in common the electric motor 2 which comprises a rotor 12 and a magnetic status part 13. The rotor 12 is journalled via suitable bearings, for example bearing bushes 14, on a stationary shaft 15, which shaft is firmly pressed into a stationary supporting part in the housing region on the high pressure side. In the embodiment shown in Figure 1, the rotary pump 4, representing the main feed pump, has a rear base plate 16 with a central bore 17 which is formed in an axially projecting central boss 18 of the supporting plate 16. One end of the shaft 15 is pressed into this bore 17 and the other end of the shaft is located in a bore 20 of the cover 8.

The magnetic status part 13 of the electric motor 2 comprises two permanent magnets 25 which are arranged in a tubular or cylindrical holding part 26 made of a magnetically permeable material. The holding part 26 serves at the same time for transmitting the clamping pressure between the individual components of the pump, exerted by the end flanges closing the housing 5, since a clamping pressure, which is brought about by the flanging 6, is exerted on the holding part 26, possibly via the brush carrier plate or other intermediate elements.

In the embodiment shown, the preliminary feed pump directly adjoining the electric motor consists of a side channel pump 3, whilst the main feed pump is a roller-vane pump 4 which is connected effectively downstream of the side channel pump so that it receives the fuel to be fed under a slight intermediate pressure.

It is understood, however, that the type and construction of these pumps is in principle, optional; hence each pump may be any kind of liquid pump, e.g. a centrifugal pump, a side channel pump, a gear pump, a rotary vane pump or any other type of pump, taking into consideration that, in the case of series connection of two positive displacement pumps without the self-regulating effect of the hydrodynamic pumps a pressure control element has to be interposed. It is important that in between the respective movable parts of each pump, for example, the pump rotors or, as applied to the present embodiment, between the impeller 30, 30a of the side channel pump 3, 3a, the slotted disc 31, 3 la of the roller-vane pump 4, 4a and the rotor 12 of the electric motor, a rotary drive is effected which excludes any adverse mechanical influences between the pumping stages.

In the embodiment represented in Figure 1, the arrangement is such that the side channel pump 3 is situated on the side of the electric motor 2 remote from the commutator region 24, and hence also from the suction connection 7. The impeller 30 of the side channel pump is fitted firmly on an extension 32 of the motor rotor 12, and in this way is rotatably journalled by means of the supporting tube 21 and the bearing bushes 14.. The extension 32 is in the form of a sleeve-like cylinder and may, for example, be injection-moulded around part of the supporting tube 21. Parts of the sleevelike, injection-moulded extension 32 may also reach as far as the lamination stack 22 of the rotor 12.In the embodiment shown, the extension 32 forms part of a pressed-on plastics driver fixed by the winding which is in a positive connection for rotary driving with the injection-moulded encasing of the laminations. The extension 32 supporting the impeller 30 may be integral with or separate from the motor rotor 12. The impeller 30, may be placed onto the extension 32 and/or is press-fitted onto same in an immovable manner. The status or base plate 33 of the side channel pump 3 on the suction side is stationarily supported within the holding part 26 of the motor and is also rotationally fixed .by the holding part 26. The attachment of the base plate 33 of the side channel pump may take place in any desired manner; thus, for example, luglike projections 34 on the periphery of the flange-like base plate 33 may engage in notches 35 of the holding part 26.

The base plate 33 of the side channel pump 3 is further supported on projections or annular flange regions 36 of a supporting plate 37 on the downstream rotary pump 4. The extension 32 from the rotor 12 passes with clearance through a central opening 38 of the base plate 33 and supports the impeller 30 between the base plate 33 and the supporting plate 37. The supporting plate 37, the intermediate plate 39 and the rear supporting plate 16 which as a stationary supporting element supports the shaft 15, are held together by means of clamping bolts 40 which, preferably distributed around the periphery, connect the block of supporting plate 37, intermediate plate 39 and base plate 16 to the closure cover flange 45 of the housing 5.The port of the suction groove of the roller-vane pump 4 is designated by numeral 41; the supporting plate 37, the intermediate plate 39 and the base plate 16 accommodate between them the slotted disc 31 of the roller-vane pump mentioned previously. The slotted disc 31 is also driven from the motor rotor 12, via the extension 32 which already supports the impeller 30. Onto the extension is moulded a driving projection or dog 42 which loosely engages in a driving groove 43 of the slotted disc 31. The slotted disc 31 itself is journalled on the shaft 15 by way of a bearing bush 44, which may, for example, be a carbon bearing bush.

In the fuel feed pump assembly shown in Figure 1 the direction of flow of the fuel is therefore from the commutator region of the electric motor and through the latter up to the preliminary feed pump, so that the entire space from the suction connection 7 up to the base plate 33 of the side channel pump is the suction chamber. In between the side channel pump and the roller-vane pump is the intermediate pressure chamber, which is sealed with respect to a high pressure chamber beyond the main feed pump, since here the seal is governed only by the slight axial clearance of the slotted disc 31. The high pressure chamber is formed between the rear supporting plate 16 of the roller-vane pump and the cover closure flange 45 of the housing which carries integrally the pressure connection 10 with a check valve 46 therein.

The supporting tube 21 and hence the motor rotor 12 and the impeller 30 are secured against axial displacement by safety rings 48 engaging into grooves 47 of the shaft 15 as well as an appropriate number of shims for the axial locking with defined play.

The embodiment of Figure 2 differs from the fuel feed pump of Figure 1 in that the preliminary pump, also in the form of a side channel pump, is spatially separated from the roller-vane pump 4a and is arranged adjoining the commutator region 24 of the electric motor 2; however, the 'reverse' direction of flow of the fuel to be delivered is retained.

The impeller 30a of the side channel pump 3a is, in this embodiment, preferably pushed-on, shrunk-on or injection-moulded close to the commutator region 24 of the electric motor 2 connected directly positively to the rotor 12, i.e. to a tapering partial region of the same.

Upstream of the impeller 30a, the base plate 50 of the side channel pump is supported stationarily, once more with the help of the holding element 26, with projections 51 of the base plate engaging in corresponding notches of the holding element 26. It is advantageous in the two embodiments of Figure 1 and Figure 2 that, owing to the spatial separation from the rotary pump of Figure 2, or to the special arrangement in the embodiment of Figure 1, the radial dimensions of the side channel pump can be relatively large, since no space for clamping bolts is required, as in the case where both pumping stages are held together by such bolts as a block. Hence a relatively good efficiency of the side channel pump can be achieved, even at the average speeds which are most suitable for the rotary pump.In the embodiment of Figure 2 the suction chamber extends from the suction connection 7 substantially only up to the commutator region 24 of the electric motor, whilst the intermediate pressure chamber is formed by the region of the electric motor and extends from behind the impeller 30a up to the supporting plate 16 of the roller-vane pump 4a. Only the supporting plate 37a of the rollervane pump 4a is different from that of Figure 1 in that it is in the form of a plain disc adjoining the motor rotor 12 and requires no projections 36 for the supportiag of the base plate 50 of the side channel pump. The components of the roller-vane pump are held together once more by means of bolts 40 and jointed to the closure cover flange 45 of the housing 5.The driving of the slotted disc 3 la of the roller-vane pump takes place via a driver element or dog 42a from a sleevelike driver member 52 which is arranged on the supporting tube 21.

WHAT WE CLAIM IS: 1. A method of feeding a liquid by means of a pumping system arranged in a common housing with an electric motor, the pumping system having a preliminary feed stage and a main feed stage, the rotary parts of which are both driven by the electric motor, in which method the liquid flowing to or from the preliminary feed stage, which directly adjoins the electric motor, flows through the electric motor, the region thereof thereby forming a suction chamber or an intermediate pressure chamber of the pumping system.

2. A feed pump assembly for a liquid, comprising a pumping system arranged in a common housing with a driving electric motor, the pumping system having a preliminary feed pump and a main feed pump, the two being hydraulically connected in series and their respective rotors being driven by the electric motor, the preliminary pump being arranged directly adjoining the electric motor so that

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. 37 on the downstream rotary pump 4. The extension 32 from the rotor 12 passes with clearance through a central opening 38 of the base plate 33 and supports the impeller 30 between the base plate 33 and the supporting plate 37. The supporting plate 37, the intermediate plate 39 and the rear supporting plate 16 which as a stationary supporting element supports the shaft 15, are held together by means of clamping bolts 40 which, preferably distributed around the periphery, connect the block of supporting plate 37, intermediate plate 39 and base plate 16 to the closure cover flange 45 of the housing 5.The port of the suction groove of the roller-vane pump 4 is designated by numeral 41; the supporting plate 37, the intermediate plate 39 and the base plate 16 accommodate between them the slotted disc 31 of the roller-vane pump mentioned previously. The slotted disc 31 is also driven from the motor rotor 12, via the extension 32 which already supports the impeller 30. Onto the extension is moulded a driving projection or dog 42 which loosely engages in a driving groove 43 of the slotted disc 31. The slotted disc 31 itself is journalled on the shaft 15 by way of a bearing bush 44, which may, for example, be a carbon bearing bush. In the fuel feed pump assembly shown in Figure 1 the direction of flow of the fuel is therefore from the commutator region of the electric motor and through the latter up to the preliminary feed pump, so that the entire space from the suction connection 7 up to the base plate 33 of the side channel pump is the suction chamber. In between the side channel pump and the roller-vane pump is the intermediate pressure chamber, which is sealed with respect to a high pressure chamber beyond the main feed pump, since here the seal is governed only by the slight axial clearance of the slotted disc 31. The high pressure chamber is formed between the rear supporting plate 16 of the roller-vane pump and the cover closure flange 45 of the housing which carries integrally the pressure connection 10 with a check valve 46 therein. The supporting tube 21 and hence the motor rotor 12 and the impeller 30 are secured against axial displacement by safety rings 48 engaging into grooves 47 of the shaft 15 as well as an appropriate number of shims for the axial locking with defined play. The embodiment of Figure 2 differs from the fuel feed pump of Figure 1 in that the preliminary pump, also in the form of a side channel pump, is spatially separated from the roller-vane pump 4a and is arranged adjoining the commutator region 24 of the electric motor 2; however, the 'reverse' direction of flow of the fuel to be delivered is retained. The impeller 30a of the side channel pump 3a is, in this embodiment, preferably pushed-on, shrunk-on or injection-moulded close to the commutator region 24 of the electric motor 2 connected directly positively to the rotor 12, i.e. to a tapering partial region of the same. Upstream of the impeller 30a, the base plate 50 of the side channel pump is supported stationarily, once more with the help of the holding element 26, with projections 51 of the base plate engaging in corresponding notches of the holding element 26. It is advantageous in the two embodiments of Figure 1 and Figure 2 that, owing to the spatial separation from the rotary pump of Figure 2, or to the special arrangement in the embodiment of Figure 1, the radial dimensions of the side channel pump can be relatively large, since no space for clamping bolts is required, as in the case where both pumping stages are held together by such bolts as a block. Hence a relatively good efficiency of the side channel pump can be achieved, even at the average speeds which are most suitable for the rotary pump.In the embodiment of Figure 2 the suction chamber extends from the suction connection 7 substantially only up to the commutator region 24 of the electric motor, whilst the intermediate pressure chamber is formed by the region of the electric motor and extends from behind the impeller 30a up to the supporting plate 16 of the roller-vane pump 4a. Only the supporting plate 37a of the rollervane pump 4a is different from that of Figure

1 in that it is in the form of a plain disc adjoining the motor rotor 12 and requires no projections 36 for the supportiag of the base plate 50 of the side channel pump. The components of the roller-vane pump are held together once more by means of bolts 40 and jointed to the closure cover flange 45 of the housing 5.The driving of the slotted disc 3 la of the roller-vane pump takes place via a driver element or dog 42a from a sleevelike driver member 52 which is arranged on the supporting tube 21.

the region of the electric motor constitutes a suction chamber or an intermediate pressure chamber of the pumping system, whereby liquid flowing to or from the preliminary feed pump flows through the electric motor.

3. A feed pump assembly as claimed in Claim 2, in which the preliminary feed pump and the main feed pump are arranged as a joint pumping block at the end of the motor remote from a commutator region thereof the region surrounding the commutator and motor rotor forming the suction chamber of the feed pump assembly.

4, A feed pump assembly as claimed in Claim 2, in which the preliminary feed pump and the main feed pump are arranged spatially separated, one at each end of the rotor of the electric motor, the rotor of the preliminary feed pump being arranged directly on the motor rotor, and the region of the motor forming the intermediate pressure chamber of the feed pump assembly.

5. A feed pump assembly as claimed in any of claims 2 to 4, in which the main feed pump is a positive displacement pump.

6. A feed pump assembly as claimed in Claim 5, in which the main feed pump comprises a roller vane pump.

7. A feed pump assembly as claimed in any of claims 2 to 6, in which the preliminary feed pump comprises a hydrodynamic pump.

8. A feed pump as claimed in Claim 7, in which the preliminary feed pump comprises a side channel pump.

9. A feed pump assembly as claimed in Claim 8, in which the rotor or impeller of the side channel pump and the rotor of the main feed pump are drivingly coupled to the rotor of the electric motor, in that the impeller of the side channel pump is press-fitted on a sleeve-like extension of the motor rotor in a fixed manner and the extension has a driving dog which projects into the rotor of the main feed pump.

10. A feed pump as claimed in Claim 9, in which the extension supporting the impeller passes through a stator or base plate of the side channel pump, which base plate is supported in a holding part which completes the magnetic flux path of the electric motor and is subjected to a clamping pressure originating from a flanging of a cover on the housing of the pump.

11. A feed pump as claimed in Claim 9 or 10, when dependent on Claim 6, in which peripheral, annular flange projections on a base plate of the roller-vane pump rest against the base plate of the side channel pump.

12. A feed pump as claimed in Claim 11, in which the base plate, an intermediate plate and a supporting plate of the roller-vane pump are clamped together by bolts, which bolts are further screwed into a flange-like closure cover part of the housing, said cover part being retained, at least indirectly, by the holding part.

13. A feed pump as claimed in Claim 8, in which the side channel pump has a base plate which is retained at the upstream side of the rotor of the side channel pump by means of a holding part.

14. A'feed pump constructed substantially as hereinbefore described with reference to and as illustrated in Figure 1 of the accompanying drawings.

15. A feed pump constructed substantially as hereinbefore described with reference to and as illustrated in Figure 2 of the accompanying drawings.