GB1582297A - Internal-combustion engine fuel feed appliances - Google Patents

Description

(54) IMPROVEMENTS IN INTERNAL-COMBUSTION ENGINE FUEL FEED APPLIANCES (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: This invention relates to a fuel feed appliance for an internal combustion engine.

A complaint made about known electric motor driven rotary fuel feed pumps is that they make too much noise during operation.

The generation of noise in these fuel pumps is due to the pressure fluctuations which occur both at the suction side and at the pressure side of the pump. In the case of a motor vehicle for example, the pressure fluctuations at the pressure side of the pump are transmitted to the body of the vehicle as sounds conducted through solids, and those at the suction side are transmitted to the tank.

A feature of the present invention is that it provides a fuel appliance in which the pressure fluctuations are largely absorbed, thus greatly reducing the generation and propagation of noise.

According to the present invention there is provided a fuel feed appliance for an internal combustion engine, having a suction chamber and a pressure chamber and having a device of elastic volume (as hereinafter defined) associated with one of said chambers and arranged to absorb pressure fluctuations in fuel passing through said one chamber.

A device of elastic volume is an hydraulic accumulator or equivalent device which can temporarily yield resiliently to store hydraulic fluid or effectively increase the volume of the said one chamber.

In a preferred embodiment of the invention the fuel feed appliance includes a pump lying between the suction chamber and the pressure chamber, the pump being drivable by an electric motor mounted in the pressure chamber.

The device of elastic volume may be either a member of moulded foam material, or an air cushion such as a closed flexible tube, made from fuel resistant material. In another embodiment the housing of the fuel feed appliance itself has yieldable regions for absorbing pressure fluctuations.

The invention will further be described, by way of example, with reference to the accompanying drawings.

A rotary fuel feed pump 1 and an electric motor 2 are combined to form the illustrated internal combustion engine fuel feed appliance. The pump and the motor are accommodated in a cup-shaped housing 3 whose bottom end has a suction connection 4 for a flexible fuel pipe, the housing being sealed by means of a cover 5 on which are arranged a pressure connection piece 6 and a non-return valve 7 acting as a pressure valve. A seal 8 is arranged between the housing 3 and the cover 5. The cover 5 is secured to the housing by means of a flange 9 on the open end of the housing 3.

The pump 1 and the electric motor 2 are disposed in the housing 3 in this order viewed from the suction end towards the pressure end, wherein the fuel fed under pressure by the pump 1 also flows around the electric motor 2 for the purpose of cooling it.

The pump 1 has a base plate 11 into the central bore of which is pressed a fixed axle 12. An intermediate plate 13 and a support 14 are arranged axially adjacent to the base plate 11. The base plate, the intermediate plate and the support plate are clamped together by means of screws 16 and accommodate the pump rotor 17 therebetween, the pump rotor 17 further being mounted on the spindle 12 by means of a bearing 18. The suction side of the pump 1 communicates with the suction chamber 19 by way of openings (not illustrated), the chamber 19 being defined by the bottom of the housing 3 and by the base plate 11.On the other hand, the pressure side of the pump 1 communicates with a pressure chamber 20 which housing the electric motor 2, leads to the pressure connection piece 6, and has an opening which leads to the suction chamber 19 and which is controlled by means of a pressure controlled relief valve 21. The pump 1 communicates with the chambers 19 and 20 by way of passages which are only 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 member 25.

The motor rotor 23 is mounted on the spindle 12 by way of bearing bushes 27.

The bearing bushes are arranged in a support tube 28 to which the stack 29 of plates, the armature winding 30 and the commutator bush 31 are secured partially by press fitting and partially by plastics filling members which, by injection-moulding them around the individual elements, also ensure a satisfactory non-rotatable and axial connection. A bush 32 of this type is arranged on that end of the support tube 28 which faces the pump, and, acting as a rotary coupling, has at least one tang 33 which engages into a complementary recess 34 in the pump rotor 17.

The commutator brushes 35 are arranged in cages 36 and slide on the commutator bush 31. The cages 36 are connected to connection terminals (not illustrated) arranged outside the housing 3.

The magnetic member 25 of the electric motor 2 comprises a permanent magnet 38 arranged in a tubular plate 39 made from magnetically permeable material.

A reservoir 41 filled with air is arranged in the suction chamber 19 of the fuel feed unit and yields resiliently when pressure fluctuations occur. As soon as the pressure in the suction chamber drops below a specific inlet pressure, the reservoir 41 expands and thus prevent pressure fluctuations from being propagated by way of the line or the mechanical suspension of the pump to parts of the motor vehicle which are capable of resonance, such as the fuel tank.

A second resilient container 42 of this type is arranged in the pressure chamber 20 of the fuel feed unit. This resilient container 42 yields when pressure fluctuations occur in the pressure chamber 20 and thereby damps them so that pressure waves can not be propagated to resonant bodies, such as the fuel tank by, for example, the pressure line of the fuel feed unit. By way of example, a resonant body of this type may also be the body of the motor vehicle.

The elastic bodies 41 and 42 can be made from a wide variety of materials and in a wide variety of shapes. The essential thing is that they damp pressure fluctuations and thus prevent undesirable and avoidable development of sound. Thus, for example, the damping bodies 41, 42 can be made from foam material having closed pores, or they may be in the form of air cushions or, alternatively, in the form of flexible tubes.

They may be of circular or elongate configuration so as to be adaptable to the available space.

It is also conceivable, although this is not shown, for portions of the housing 3 to have outwardly yielding soft locations for the purpose of undertaking the resilient damping, the ambient air acting as the damping volume.

WHAT WE CLAIM IS: 1. A fuel feed appliance for an internalcombustion engine, a suction chamber and a pressure chamber and having a device of elastic volume (as hereinbefore defined) associated with one of said chambers and arranged to absorb pressure fluctuations in fuel passing through said one chamber.

2. A fuel feed appliance as claimed in claim 1, in which a pump separates the suction chamber from the pressure chamber and is arranged to be driven by an electric motor.

3. A fuel feed appliance as claimed in claim 2, in which the electric motor is mounted in the pressure chamber.

4. A fuel feed appliance as claimed in claims 1 to 3, in which the device is a moulded member made from foam material having closed pores.

5. A fuel feed appliance as claimed in claims 1 to 3, in which the device is an air cushion made from fuel-resistant material.

6. A fuel feed appliance as claimed in claim 5, in which the air cushion is a flexible tube which is closed at both ends.

7. A fuel feed appliance as claimed in claims 1 to 3, in which the housing of the pump is of elastic construction and acts as the device.

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

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. bearing 18. The suction side of the pump 1 communicates with the suction chamber 19 by way of openings (not illustrated), the chamber 19 being defined by the bottom of the housing 3 and by the base plate 11. On the other hand, the pressure side of the pump 1 communicates with a pressure chamber 20 which housing the electric motor 2, leads to the pressure connection piece 6, and has an opening which leads to the suction chamber 19 and which is controlled by means of a pressure controlled relief valve 21. The pump 1 communicates with the chambers 19 and 20 by way of passages which are only 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 member 25. The motor rotor 23 is mounted on the spindle 12 by way of bearing bushes 27. The bearing bushes are arranged in a support tube 28 to which the stack 29 of plates, the armature winding 30 and the commutator bush 31 are secured partially by press fitting and partially by plastics filling members which, by injection-moulding them around the individual elements, also ensure a satisfactory non-rotatable and axial connection. A bush 32 of this type is arranged on that end of the support tube 28 which faces the pump, and, acting as a rotary coupling, has at least one tang 33 which engages into a complementary recess 34 in the pump rotor 17. The commutator brushes 35 are arranged in cages 36 and slide on the commutator bush 31. The cages 36 are connected to connection terminals (not illustrated) arranged outside the housing 3. The magnetic member 25 of the electric motor 2 comprises a permanent magnet 38 arranged in a tubular plate 39 made from magnetically permeable material. A reservoir 41 filled with air is arranged in the suction chamber 19 of the fuel feed unit and yields resiliently when pressure fluctuations occur. As soon as the pressure in the suction chamber drops below a specific inlet pressure, the reservoir 41 expands and thus prevent pressure fluctuations from being propagated by way of the line or the mechanical suspension of the pump to parts of the motor vehicle which are capable of resonance, such as the fuel tank. A second resilient container 42 of this type is arranged in the pressure chamber 20 of the fuel feed unit. This resilient container 42 yields when pressure fluctuations occur in the pressure chamber 20 and thereby damps them so that pressure waves can not be propagated to resonant bodies, such as the fuel tank by, for example, the pressure line of the fuel feed unit. By way of example, a resonant body of this type may also be the body of the motor vehicle. The elastic bodies 41 and 42 can be made from a wide variety of materials and in a wide variety of shapes. The essential thing is that they damp pressure fluctuations and thus prevent undesirable and avoidable development of sound. Thus, for example, the damping bodies 41, 42 can be made from foam material having closed pores, or they may be in the form of air cushions or, alternatively, in the form of flexible tubes. They may be of circular or elongate configuration so as to be adaptable to the available space. It is also conceivable, although this is not shown, for portions of the housing 3 to have outwardly yielding soft locations for the purpose of undertaking the resilient damping, the ambient air acting as the damping volume. WHAT WE CLAIM IS:

1. A fuel feed appliance for an internalcombustion engine, a suction chamber and a pressure chamber and having a device of elastic volume (as hereinbefore defined) associated with one of said chambers and arranged to absorb pressure fluctuations in fuel passing through said one chamber.

2. A fuel feed appliance as claimed in claim 1, in which a pump separates the suction chamber from the pressure chamber and is arranged to be driven by an electric motor.

3. A fuel feed appliance as claimed in claim 2, in which the electric motor is mounted in the pressure chamber.

4. A fuel feed appliance as claimed in claims 1 to 3, in which the device is a moulded member made from foam material having closed pores.

5. A fuel feed appliance as claimed in claims 1 to 3, in which the device is an air cushion made from fuel-resistant material.

6. A fuel feed appliance as claimed in claim 5, in which the air cushion is a flexible tube which is closed at both ends.

7. A fuel feed appliance as claimed in claims 1 to 3, in which the housing of the pump is of elastic construction and acts as the device.

8. An internal-combustion engine fuel

feed appliance constructed and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.