GB1561426A

GB1561426A - Rotary fuel-pumps

Info

Publication number: GB1561426A
Application number: GB4064377A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1976-10-02
Filing date: 1977-09-30
Publication date: 1980-02-20
Also published as: DE2644704A1; JPS5348207A

Description

(54) IMPROVEMENTS IN ROTARY FUEL-PUMPS (71) We, ROBERT Bonsai G.m.b.H., 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 rotary fuel pump.

During mixed friction or dry running, which sometimes occurs, known fuel pumps tend to suffer intense wear of the track upon which pumping elements, guided by a rotor, rub. Such wear causes a sharp increase in the current consumption of the electric drive motor and a reduction in the speed, the delivered fuel quantity and the pressure of the system, this finally leading to failure in supplying fuel to the internal-combustion engine.

A rotary fuel pump of the sliding, or roller, vane type according to the invention, comprises an intermediate plate which is clamped between fixed end plates and has a circular aperture into which a circular ring made of a plastics material is pressed, and sliding, or roller, vanes supported so as to be movable into contact with the inner wall of said ring by a rotor situated within the aperture and extending between the end plates.

During mixed friction or even dry running of such a pump, wear which would result in failure of the pump is not so likely to occur between the pump body and track.

A further advantage is the relatively slight increase in the current consumption after a long period of operation. Reliable operation and low energy consumption are, however, a fundamental significance for such a fuel pump.

It is particularly advantageous to prevent the plastics ring from rotating since such a ring may work loose as a consequence of relaxation and this might cause the pump to break down. This can be achieved by providing radially inwardly projecting teeth in the aperture to bite into the plastics ring.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a longitudinal section through a fuel feed unit having a pump according to the invention; Fig. 2 is an end view of an intermediate plate of the pump, and Fig. 3 is a section through a plastics ring in the pump.

A fuel feed unit comprises a rotary fuel pump 1 of the sliding, or roller, vane type and an electric motor 2. The pump and motor are accommodated in a barrel-shaped housing 3 which comprises, at one end, a suction connection 4 for a fuel hose (not shown) and which is sealed at the other end by a cover 5 upon which a pressure connection pipe 6 and a relief valve 7, serving as a pressure valve, are disposed. A seal 8 is disposed between the housing 3 and the cover 5. The cover 5 is secured to the housing by a flange 9 at the open end of the housing 3.

Viewed from the suction end to the pressure end, first the pump 1 and then the electric motor 2 are disposed in the housing 3, whereby fuel conveyed under pressure by the pump 1 flows through the electric motor 2 so as to cool the motor also.

The pump 1 comprises a fixed outer end or base plate 11 and a fixed shaft 12 is pressed into the central bore of this plate.

An intermediate plate 13 and a fixed inner end or supporting plate 14 are disposed axially adjacent to the base plate 11. The base plate, the intermediate plate and the supporting plate are clamped together by screws 16 and accommodate therebetween a pump rotor 17 which is mounted on the shaft 12 by means of a bearing 18. The pump 1 is connected at its suction side to the chamber 19 by way of ports (not shown), the chamber being defined by the base of the housing 3 and by the base plate 11.

However, the pressure side of the pump 1 is connected to a chamber 20 which in fact is the interior of the electric motor 2 and leads to the pressure pipe 6. The base plate 11 has an aperture which communicates with the chamber 20 and which is controlled by a pressure control valve 21 and leads to the chamber 19. The connections leading from pump 1 to the chambers 19 and 20 are merely ports which are controlled by the pump rotor, but which are preferably open passages. The electric motor 2 comprises a motor rotor 23, a commutator 24 and a magnetic part 25.

The motor rotor 23 is mounted on the axle 12 by way of bearing bushes 27. The bearing bushes are disposed in a supporting tube 28 upon which a stack of laminations 29, a bundle of armature windings 30 and a commutator 31 are mounted. Mounting is effected partly by means of a pressing-on process and partly by means of plastics filler parts which also ensure a good rotational and axial connection because of injectionmoulding around the individual elements.

Such a filler part is a bush 32 which is disposed on the supporting tube 28 at the end facing the pump and includes at least one carrier pin 33 which engages in an appropriate recess 34 in the pump rotor 17 to form a rotary coupling.

Brushes 35, which are disposed in cages 36, slide on the commutator 31. The cages 36 are connected to terminals which are disposed outside the housing 3 and are not shown.

The magnetic part 25 of the electric motor 2 comprises a permanent magnet 38 which is disposed in a tubular sheath 39 made of a magnetically conductive material.

Disposed between the plate 13 and the pump rotor 17 is a plastics material bear nag ring 40 which is pressed into the inner aperture 41 of the intermediate plate 13 and which is preferably made of polyimide. Sliding, or roller, vanes 42 guided in the pump rotor 17 slide on this bearing ring 40 and are urged against the bearing ring 40 by centrifugal force. The intermediate plate 13 is eccentrically disposed relative to the axis of rotation of the rotor 17 so that a crescentshaped chamber which is sub-divided by the pump elements 42 is produced between the pump rotor and the intermediate plate 13.

Fig. 2 is a view of the intermediate plate 13 with the pressed-in bearing ring 40. Disposed in the inner aperture 41 of the intermediate plate 13 are teeth 44 which engage in the outer surface of the plastics ring 40, whereby relative rotation between the bearing ring 40 and the intermediate plate 13 is prevented. This bearing ring 40 is, as stated, pressed axially into the inner aperture 41 of the intermediate plate 13, and during the pressing process, the teeth 44 make appropriate grooves in the outer surface of the bearing ring 40.

In order to avoid tilting whilst the bearing ring 40 is being pressed in, one outer edge of the bearing ring 40 is provided with a chamfer 43, as shown in Fig. 3. Any number of teeth 44 may be provided in the inner aperture 41 of the intermediate plate 13, and in order to simplify the pressing-in process, the teeth 44 may have sharp edges in the axial direction.

Because the bearing ring is secured in this way, it can no longer work loose through a relaxation of stress, for it is clamped, when installed, axially between the base plate 11 and the supporting plate 14 and effectively splined into the intermediate plate by the teeth 44. This simple type of positive connection is particularly advantageous because of the removal of material when the ring is being pressed in.

WHAT WE CLAIM IS: 1. A rotary fuel pump of the sliding, or roller, vane type and comprising an intermediate plate which is clamped between fixed end plates and has a circular aperture into which a circular ring made of a plastics material is pressed, and sliding, or roller, vanes supported so as to be movable into contact with the inner wall of said ring by a rotor situated within the aperture and extending between the end plates.

2. A rotary fuel pump as claimed in claim 1, in which the ring is made of polyimide.

3. A rotary fuel pump as claimed in claim 1 or 2, in which radially inwardly projecting teeth are disposed in the aperture and engage the ring to positively prevent rotation thereof.

4. A rotary fuel pump is claimed in any preceding claim, in which the ring can be pressed in axially.

5. A rotary fuel pump as claimed in claim 4, in which the ring is bevelled on one outer edge to facilitate insertion.

6. A rotary fuel pump as claimed in claim 4 or 5 when dependent from claim 3 in which the teeth have sharp edges in the axial direction.

7. A rotary fuel pump as claimed in any preceding claim which forms part of a fuel unit including an electric motor.

8. A rotary fuel pump constructed substantially as herein described with reference to and as illustrated in the accompanying drawings.

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

Claims

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

11 has an aperture which communicates with the chamber 20 and which is controlled by a pressure control valve 21 and leads to the chamber 19. The connections leading from pump 1 to the chambers 19 and 20 are merely ports which are controlled by the pump rotor, but which are preferably open passages. The electric motor 2 comprises a motor rotor 23, a commutator 24 and a magnetic part 25.

The motor rotor 23 is mounted on the axle 12 by way of bearing bushes 27. The bearing bushes are disposed in a supporting tube 28 upon which a stack of laminations 29, a bundle of armature windings 30 and a commutator 31 are mounted. Mounting is effected partly by means of a pressing-on process and partly by means of plastics filler parts which also ensure a good rotational and axial connection because of injectionmoulding around the individual elements.

Such a filler part is a bush 32 which is disposed on the supporting tube 28 at the end facing the pump and includes at least one carrier pin 33 which engages in an appropriate recess 34 in the pump rotor 17 to form a rotary coupling.

Brushes 35, which are disposed in cages 36, slide on the commutator 31. The cages 36 are connected to terminals which are disposed outside the housing 3 and are not shown.

The magnetic part 25 of the electric motor 2 comprises a permanent magnet 38 which is disposed in a tubular sheath 39 made of a magnetically conductive material.

Disposed between the plate 13 and the pump rotor 17 is a plastics material bear nag ring 40 which is pressed into the inner aperture 41 of the intermediate plate 13 and which is preferably made of polyimide. Sliding, or roller, vanes 42 guided in the pump rotor 17 slide on this bearing ring 40 and are urged against the bearing ring 40 by centrifugal force. The intermediate plate 13 is eccentrically disposed relative to the axis of rotation of the rotor 17 so that a crescentshaped chamber which is sub-divided by the pump elements 42 is produced between the pump rotor and the intermediate plate 13.

Fig. 2 is a view of the intermediate plate 13 with the pressed-in bearing ring 40. Disposed in the inner aperture 41 of the intermediate plate 13 are teeth 44 which engage in the outer surface of the plastics ring 40, whereby relative rotation between the bearing ring 40 and the intermediate plate 13 is prevented. This bearing ring 40 is, as stated, pressed axially into the inner aperture 41 of the intermediate plate 13, and during the pressing process, the teeth 44 make appropriate grooves in the outer surface of the bearing ring 40.

In order to avoid tilting whilst the bearing ring 40 is being pressed in, one outer edge of the bearing ring 40 is provided with a chamfer 43, as shown in Fig. 3. Any number of teeth 44 may be provided in the inner aperture 41 of the intermediate plate 13, and in order to simplify the pressing-in process, the teeth 44 may have sharp edges in the axial direction.

Because the bearing ring is secured in this way, it can no longer work loose through a relaxation of stress, for it is clamped, when installed, axially between the base plate 11 and the supporting plate 14 and effectively splined into the intermediate plate by the teeth 44. This simple type of positive connection is particularly advantageous because of the removal of material when the ring is being pressed in.

WHAT WE CLAIM IS: 1. A rotary fuel pump of the sliding, or roller, vane type and comprising an intermediate plate which is clamped between fixed end plates and has a circular aperture into which a circular ring made of a plastics material is pressed, and sliding, or roller, vanes supported so as to be movable into contact with the inner wall of said ring by a rotor situated within the aperture and extending between the end plates.
2. A rotary fuel pump as claimed in claim 1, in which the ring is made of polyimide.
3. A rotary fuel pump as claimed in claim 1 or 2, in which radially inwardly projecting teeth are disposed in the aperture and engage the ring to positively prevent rotation thereof.
4. A rotary fuel pump is claimed in any preceding claim, in which the ring can be pressed in axially.
5. A rotary fuel pump as claimed in claim 4, in which the ring is bevelled on one outer edge to facilitate insertion.
6. A rotary fuel pump as claimed in claim 4 or 5 when dependent from claim 3 in which the teeth have sharp edges in the axial direction.
7. A rotary fuel pump as claimed in any preceding claim which forms part of a fuel unit including an electric motor.
8. A rotary fuel pump constructed substantially as herein described with reference to and as illustrated in the accompanying drawings.