GB1602237A

GB1602237A - Fuel feed pump assembly

Info

Publication number: GB1602237A
Application number: GB2196978A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1977-10-12
Filing date: 1978-05-24
Publication date: 1981-11-11
Also published as: DE2745760A1

Description

(54) FUEL FEED PUMP ASSEMBLY (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 statement: The present invention relates to a fuel feed pump assembly in which the pump system comprises two separate operatively connected pump stages arranged in series, both of which are driven by an electric motor.

Fuel feed pump assemblies comprising two separate operatively connected, serially arranged pump stages, both of which are driven by a common electric motor, are already known. The arrangement of two pump stages, a first of which operates as a primary feed pump and the second of which operates as a main feed pump, is advantage- ous since, owing to deterioration in fuel quality, faults in the operation of a rollercell pump which is generally used as the main feed pump may occur to an increasing extent in the feeding of petrol at high temperatures. This can be prevented by feeding the fuel at a pressure slightly above atmospheric pressure, whereby a substantial mcrease m vapour tormation may be eliminated as a cause of failure.Generation of the primary pressure is then effected by the primary feed stage in the form of a hydrodynamic pump having a venting arrangement, which may be either connected upstream as a separate electrical fuel pump or be integrated as a primary stage in the region of the main feed pump, which is generally a roller-cell pump. In such an integrated two-stage pump difficulties may arise in coupling the two pump rotors, if these, as is usual, are to be driven by a common electric motor. It is necessary in particular to avoid mechanical interference between the rotors of the two pump stages, and it is also necessary to separate the high-pressure chamber from the intermediate pressure chamber by sealing the pump stages with respect to each other.A further difficulty when the dimensions of the housing for accommodating the pump stages and the electric driving motor are predetermined, is that the roller-cell pump generally used as the main feed stage must be driven at a moderate speed, while a side-channel pump, in the form of a primary feed pump, is able to generate only a small pressure at such speeds, although, on the other hand, the size of the side-channel pump, in its conventional arrangement in which the two pumps are combined to form a common pump unit fitted in front of the electric motor, is restricted substantially owing to the screws which hold the pump components together.

Because of these clamping screws the primary feed stage cannot, so far as its radial dimensions are concerned, fully utilise the space available in the housing.

In accordance with this invention, a fuel feed pump assembly comprises a primary feed pump, a main feed pump and an electric driving motor, the two pumps and the driving motor being arranged in a common housing with the motor disposed between the pumps and respectively coupled thereto, such that fuel drawn in through a suction opening at one end of the housing by the primary feed pump flows from the outlet of the primary feed pump, through the electric motor and to the inlet of the main feed pump and is delivered by the latter to a pressure outlet opening at the other end of the housing.

In contrast with the known pumps an advantage of a fuel feed pump assembly in accordance with this invention is that the rotors of the two pump stages used can be accurately driven by the electric motor without mutual interference or interaction, that assembly and adjustment of the two pump stages can be effected independently of each other, and that, particularly in the case of an upstream-connected primary side-channel pump, its size, and thus also its efficiency at a predetermined speed, may be increased substantially.

A further advantage of the invention is that the complete fuel feed pump assembly is of relatively simple construction and can be accurately adjusted.

The invention is further described hereinafter, by way of example only, with reference to the accompanying drawing in which a partial longitudmal section through a fuel feed pump assembly in accordance with this invention is illustrated.

In the fuel feed pump assembly shown in the drawing, the pump system comprises two pump stages, namely, a primary feed pump 1 and a main feed pump 2, which are accommodated separately in a cup-shaped housing 5, and which include between them the region of the electric motor 3. The cupshaped housing 5 is provided on its base with a suction connection 6, to which a fuel hose (not shown) may be connected. At its opposite end the housing is sealed by means of a cover 7, on which a pressure-connecting nipple 8 and a non-return valve 9 are arranged. A seal is arranged between the housing 5 and the cover 7; the cover 7 is attached to the open end of the housing 5 by means of a flanged rim 11; the flanged rim serves at the same time to clamp all the internal components of the assembly rigidly together, as explained hereinafter.

Inside the housing, when viewed from the suction side in a direction towards the compression side, are first the primary feed pump 1, next to it the electric motor 3, and then the main feed pump 2, the slightly pressurised fuel delivered by the primary feed pump 1 and fed to the suction side of the main feed pump flowing also through the electric motor 2 and its components in order to cool them.

The electric driving motor is discussed hereinafter only in so far as this is essential to understanding the invention; it comprises a motor rotor 12 and a magnetic stator 13.

The motor rotor 12 is supported on suitable bearings, such as bearing bushes 14, on a stationary shaft 15, which is a rigid press-fit in stationary supporting members in the inlet and outlet regions of the housing, whereby it is rigidly supported. In the embodiment of the invention shown, the primary feed pump, which is a side-channel pump, has a front baseplate 16 having a central bore 17, in which the shaft 15 is a pressfit. The other end of the shaft is press-fitted into a central bore 18 of a rear baseplate 19 of the second pump stage.

The bushes 14 supporting the motor rotor 12 on the shaft 15 are arranged in a supporting tube 20, upon which an armature core 21 and an armature winding 22 are arranged. Furthermore, a commutator 24 is attached, for example by press-fitting, to the supporting tube 20.

carbon brushes 25, arranged in cages 26, slide on the commutator 24. The cages 26 are electrically connected to terminals 23 arranged in the cover. The magnetic stator 13 of the electric motor 3 comprises two permanent magnets 27 arranged in a tubular or cylindrical retaining member 28 made of magnetically permeable material. This tubular retaining member 28 serves at the same time to clamp the front baseplate 16 of the primary-stage pump, a corresponding clamping force being exerted upon the retaining member 28, possibly via further intervening components, by the cover 7 which is retained by the flanged rim 11. The two pump stages are driven simultaneously by the electric motor.In the embodiment of the invention shown, the first pump stage, or primary feed pump 1, next to the suction connection 6, comprises a side-channel pump, while the main feed pump, which receives the fuel delivered by the latter at a pressure slightly above atmospheric pressure, is in the form of a roller-cell pump.

Basically, however, these pumps may be of any desired type or construction; each stage may thus be considered generally as a hydraulic pump, namely, a centrifugal pump, a side-channel pump, a gear pump, a rollercell pump, or any other type of rotary pump, although, if two positive-displacement pumps are serially coupled, owing to the absence of the self-regulating effect of hydrodynamic pumps it is necessary to include a pressure-regulating element between them.

The baseplate 16 of the side-channel pump 1 is in abutment via a chamfered annular mating surface 30 with a corresponding annular frustum-shaped surface 31 of the housing and is accurately supported thereby. As already mentioned, the baseplate 1 is retained in this position by means of the retaining member 8, which engages with a shoulder 32 on the baseplate. The baseplate may thus be a clearance fit; alternatively, however, it may be a press-fit in a corresponding fitting bore in the housing.

The side of the rotor 33 adjacent to the baseplate 16 forms the stationary member of the side-channel pump ieratively con nectable to the rotor 33; it is unnecessary to discus here in detail the construction and method of operation of the two types of pump used, since such hydraulic pumps are basically kro'vn.

In the embodiri1eilt of t invention shown ifl the drawing, the rçtsr 33 is main tained central and at tihe desired axial distance from tlie baseplate 1 bv means of a boss-like supporting merlibe} 34 which is preferably formed integral with the rotor 33 or may be inJectioll-rnou1ded on The latter, and which extends along the supporting tube 2C lbeo veen the latter and The armature winding 22. In order to clamp this support Ing member 34 rigidly, it may be enlarged in the region of the motor rotor 12 and embrace the armature core 21.

Alternatively, the supporting member 34 may be injection-moulded integrally with the plastics-material insulation of the armature core. In order to prevent its axial displacement, the motor rotor 12, or, more precisely, the supporting tube 20 upon which it is supported, is locked by means of locking rings 56 which engage in grooves 55 in the axle 15, whereby the axial position of the rotor 33 and its fixed alignment with respect to the baseplate 16 are ensured. The essential feature here is that the shaft 15 is retained owing to its being a press-fit in the central bore 17 of the baseplate 16.

Alternatively, however, it is possible to support the rotor 33 rotatably via a bearing bush (not shown) on the shaft 15 and to drive the rotor 33 via a driver element which engages in a corresponding recess in the rotor 33. The supporting member 34 is preferably a suitable moulding of plastics material. Such a construction and arrangement of the side-channel pump. without the clamping screws and other mechanical coupling means which would be necessary if the side-channel pump were to lie proximate to the second pump stage permits an otherwise impossible increase in the radial dimension of the side-channel pump so that the latter may have a substantially increased diameter. Improved performance of the pump at a given speed is then also achieved, so that any loss of pressure which may occur between this primary feed pump and the main feed pump is amply compensated.

To the right in the plane of the drawing, the retaining member 28 first abuts the brush support plate 35, which is in abutment with the baseplate 36 of the roller-cell pump 2. There then follow the intermediate plate 37 and the rear baseplate 19 or support plate of the roller-cell pump, which baseplate has a salient boss-like extension 38, extending in a direction towards the pressure connection 8, and, as already mentioned, supporting the other end of the shaft 15 which is a press-fit in its central bore 18.

The baseplate 36 and the support plate 19 together with the intermediate plate 37 of the roller-cell pump include between them the slotted disc 39 of the roller-cell pump, which is seated via a bearing bush 40 on the shaft 15 and is driven by the rotor 12 of the electric motor 3 by means of a driver element 41. The driver element 41 may be any sleeve-type member, preferably a plastics element which is fastened to the supporting tube 20 in the region of or adjacent to the commiutator 24 and which engages via a driving dog 43 in a co:responding receiving slot 44 in the slotted disc 39 in order to couple the roller-cd pump to the motor.

The cover 7 is provided with a wide axialflange 5f) one side of which abuts the support plate 19 of the roller-cell pump 2, so that. as from this point, the complete internal assembly of the fuel feed pump assembly is held under a clamping force, and on whose other side an annular groove 51 receives the flanged rim 11 on the end of the housing. Thus, the high-pressure chamber of the main feed pump is formed between the cover 7 and the support plate 19. The construction elements of the main feed pump or roller-cell pump are held together and adjusted relative to one another prior to assembly by means of screws 52, which are arranged in the region of the electrical connecting terminals and are clamped by means of nuts 53.The shanks of the screws extend as far as the brush support plate 35, so that the brush support plate, the construction elements of the roller-cell pump, and the cover 7, together form a unitary assembly.

The screw 2 extends through tubular plas- tics insulating members 54 and 55, which extend via aligned bores in the baseplate 36, the intermediate plate 37, and the support plate 19, at one end of the screw, and via the cover 7 at its other end. A further seal 56, encircling the screw 52, is provided for sealing between the support plate 19 and the cover 7.

WHAT WE CLAIM IS: 1. A fuel feed pump assembly comprising a primary feed pump, a main feed pump and an electric driving motor, the two pumps and the driving motor being arranged in a common housing with the motor disposed between the pumps and respectively coupled thereto, such that fuel drawn in through a suction opening at one end of the housing by the primary feed pump flows from the outlet of the primary feed pump, through the electric motor and to the inlet of the main feed pump and is delivered by the latter to a pressure outlet opening at the other end of the housing.

2. A fuel feed pump assembly as claimed in claim 1, in which the rotor of the primary feed pump is supported by the motor rotor via a boss-like supporting member.

3. A fuel feed pump as claimed in claim 2, in which the supporting member is made of plastics material, formed by injection moulding on the rotor of the primary feed pump, and extends in the form of a sleeve between the supporting tube and an anna- ture winding of the electric motor.

4. A fuel feed pump assembly as claimed in any of claims 1 to 3, in which a front baseplate pertaining to the primary feed pump is a press-fit or is a clearance fit in e housing and is retained lby means o a retaining member pertaining to a magnetic element of the electric motor, upon which retaining member a darripiug force is exertable, via at least some of the components of the main feed sump, by a cover which is sealed in the housing by a flanged rim

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. may be injection-moulded integrally with the plastics-material insulation of the armature core. In order to prevent its axial displacement, the motor rotor 12, or, more precisely, the supporting tube 20 upon which it is supported, is locked by means of locking rings 56 which engage in grooves 55 in the axle 15, whereby the axial position of the rotor 33 and its fixed alignment with respect to the baseplate 16 are ensured. The essential feature here is that the shaft 15 is retained owing to its being a press-fit in the central bore 17 of the baseplate 16. Alternatively, however, it is possible to support the rotor 33 rotatably via a bearing bush (not shown) on the shaft 15 and to drive the rotor 33 via a driver element which engages in a corresponding recess in the rotor 33. The supporting member 34 is preferably a suitable moulding of plastics material. Such a construction and arrangement of the side-channel pump. without the clamping screws and other mechanical coupling means which would be necessary if the side-channel pump were to lie proximate to the second pump stage permits an otherwise impossible increase in the radial dimension of the side-channel pump so that the latter may have a substantially increased diameter. Improved performance of the pump at a given speed is then also achieved, so that any loss of pressure which may occur between this primary feed pump and the main feed pump is amply compensated. To the right in the plane of the drawing, the retaining member 28 first abuts the brush support plate 35, which is in abutment with the baseplate 36 of the roller-cell pump 2. There then follow the intermediate plate 37 and the rear baseplate 19 or support plate of the roller-cell pump, which baseplate has a salient boss-like extension 38, extending in a direction towards the pressure connection 8, and, as already mentioned, supporting the other end of the shaft 15 which is a press-fit in its central bore 18. The baseplate 36 and the support plate 19 together with the intermediate plate 37 of the roller-cell pump include between them the slotted disc 39 of the roller-cell pump, which is seated via a bearing bush 40 on the shaft 15 and is driven by the rotor 12 of the electric motor 3 by means of a driver element 41. The driver element 41 may be any sleeve-type member, preferably a plastics element which is fastened to the supporting tube 20 in the region of or adjacent to the commiutator 24 and which engages via a driving dog 43 in a co:responding receiving slot 44 in the slotted disc 39 in order to couple the roller-cd pump to the motor. The cover 7 is provided with a wide axialflange 5f) one side of which abuts the support plate 19 of the roller-cell pump 2, so that. as from this point, the complete internal assembly of the fuel feed pump assembly is held under a clamping force, and on whose other side an annular groove 51 receives the flanged rim 11 on the end of the housing. Thus, the high-pressure chamber of the main feed pump is formed between the cover 7 and the support plate 19. The construction elements of the main feed pump or roller-cell pump are held together and adjusted relative to one another prior to assembly by means of screws 52, which are arranged in the region of the electrical connecting terminals and are clamped by means of nuts 53.The shanks of the screws extend as far as the brush support plate 35, so that the brush support plate, the construction elements of the roller-cell pump, and the cover 7, together form a unitary assembly. The screw 2 extends through tubular plas- tics insulating members 54 and 55, which extend via aligned bores in the baseplate 36, the intermediate plate 37, and the support plate 19, at one end of the screw, and via the cover 7 at its other end. A further seal 56, encircling the screw 52, is provided for sealing between the support plate 19 and the cover 7. WHAT WE CLAIM IS:

1. A fuel feed pump assembly comprising a primary feed pump, a main feed pump and an electric driving motor, the two pumps and the driving motor being arranged in a common housing with the motor disposed between the pumps and respectively coupled thereto, such that fuel drawn in through a suction opening at one end of the housing by the primary feed pump flows from the outlet of the primary feed pump, through the electric motor and to the inlet of the main feed pump and is delivered by the latter to a pressure outlet opening at the other end of the housing.

thereof.

5. A fuel feed pump assembly as claimed in any of claims 1 to 4, in which the motor rotor of the electric motor is supported via a supporting tube upon a stationary shaft whose two ends are a press-fit in respective bores of flange-like plates pertaining to components of the two pumps.

6. A fuel feed pump assembly as claimed in claim 5, in which the main feed pump has a rear support plate provided with a boss-like enlargement in whose central bore the stationary shaft is a press-fit, and in which the main feed pump also has a baseplate and a rotor which is retained between the rear support plate and said baseplate, the main feed pump rotor being driven via a driver element attached to the supporting tube at the side of the electric motor remote from the primary feed pump.

7. A fuel feed pump assembly as claimed in claim 6, in which the baseplate, an intermediate plate and the support plate of the main feed pump and the adjacent cover are clamped together by means of screws, which at the same time form electrical terminal connections for a brush support plate of the electric motor.

8. A fuel feed pump assembly as claimed in any preceding claim in which the primary feed pump comprises a sidechannel pump.

9. A fuel feed pump assembly as claimed in any preceding claim, in which the main feed pump comprises a roller-cell pump.

10. A fuel feed pump assembly con- structed and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.