GB2158652A - Hollow casing with a plate provided with air outlet openings - Google Patents

Abstract

A hollow casing, supporting a rotor, comprises an air circulation cooling circuit and a cross or end plate (4) provided with openings (5) separated one from the others by radial arms (15), through which openings the cooling air flows out of the casing, each arm having a profiled straight section in the form of an aircraft wing and directed in such a manner as to minimise the aerodynamic turbulence of the air exhaust. An application is the construction of a silent alternator for motor vehicles. <IMAGE>

Description

SPECIFICATION Hollow casing with a plate provided with air outlet openings Some rotary electric motors, such as alternators fitted on cars, have a hollow casing, supporting a rotor at least partly contained in said casing, comprising an air circulation cooling circuit, and a cross plate provided with openings separated one from the others by substantially radial rams, through which the cooling air flows out of the casing, each arm having a profiled straight section and directed in such a manner as to minimize the aerodynamic turbulence of the air exhaust.

In a machine of this type, the outflow of air is opposed by the arms of the casing end plate which connect said plate to the remainder of the casing.

At present, substantial turbulences are produced in the area of said arms, and the result is the production of a substantial sound level.

It is particularly with a view to reducing the operation noise of the above-mentioned motors that, according to the invention, each arm has a straight section in the form of an aircraft wing.

The principal advantage resulting from the adoption of the provisions in conformity with the invention is the obtaining of a substantial noise reduction, sought in particular in the applications made in automobile construction.

The invention will be better understood, and secondary characteristics and their advantages will become clear in the course of the description of an embodiment given below as an example.

It is understood that the description and drawings are given only indicatively and non limitatively.

Reference will be made to the attached drawings in which: Figure 1 is a simplified axial section of an alternator embodying the invention; Figure 2 is a view along ll-ll of Figure 1; and Figure 3 is a section along Ill-Ill of Figure 2.

The motor vehicle alternator represented in Figure 1 comprises: - a casing 1 comprising one rear cross plate 2 provided with air inflow openings 3 and a front cross plate 4 provided with air outifow openings 5; - a stator 6, comprising in particular a stack of magnetic sheets, fixed relative to casing 1; - a rotating shaft 7, mounted so as to rotate relative to the casing 1 by means of rear 8 and front 9 roller bearings; - a rotor 10, solid in rotation with shaft 7 and disposed inside the casing 1; - a fan wheel 11, fixed on a part of shaft 7 which projects outside the casing 1 in the vicinity of the front plate 4; - a pulley 12 which is fixed on the end of said part of shaft 7, by means of a washer 13 and a screw and nut assembly 14, and is adapted, by co-operating with a driving belt, to effect the rotational drive of the shaft 7, of the rotor 10 and of the fan wheel 11.

The front plate 4 has several arms 15 which extend substantially radially and separate the various openings 5 one from the others. These arms 15 have a profiled form, in the shape of an aircraft wing (Fig.3) and are so directed relative to the axis of rotation of the rotor 10 that their section is substantially parallel with the direction D of the air outflow through the openings 5.

When the rotor 10 of the alternator is driven in rotation, the fan wheel 11 creates at the front a depression which exhausts air and forces it to go through the inside of the casing 1 from the rear forward. The air flow issuing from the casing through the openings 5 moves along the arms 15 without impact and without turbulence, so that the corresponding noise is low and reduced relative to previous arrangements.

The invention is not limited to the embodiment shown, but, on the contrary, covers all alternatives that may be introduced into it without departing from its framework, or its concept.

1. A hollow casing, supporting a rotor at least partly contained in said casing, comprising an air circulation cooling circuit, and a cross plate provided with openings separate done from the others by substantially radial arms through which the cooling air flows out of the casing, each arm having a profiled straight section and being directed in such a manner as to minimize the aerodynamic turbulence of the air exhaust, characterised in that each arm has a straight section in the form of an aircraft wing.

2. A hollow casing supporting a rotor at least partly contained in said casing, comprising an air circulation cooling circuit, and a cross plate provided with openings separated one from the others by substantially radial arms, through which the cooling air flows out of the casing, each arm having a profiled straight section and being directed in such a manner as to minimize the aerodynamic turbulence of the air exhaust, characterised by the form and the direction of the straight section of each arm such as described and represented on the drawings.

3. A hollow casing substantially as described herein with reference to the accompanying drawings.

4. An alternator comprising a rotor disposed within a hollow casing in accordance with any preceding claim.

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

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Hollow casing with a plate provided with air outlet openings Some rotary electric motors, such as alternators fitted on cars, have a hollow casing, supporting a rotor at least partly contained in said casing, comprising an air circulation cooling circuit, and a cross plate provided with openings separated one from the others by substantially radial rams, through which the cooling air flows out of the casing, each arm having a profiled straight section and directed in such a manner as to minimize the aerodynamic turbulence of the air exhaust. In a machine of this type, the outflow of air is opposed by the arms of the casing end plate which connect said plate to the remainder of the casing. At present, substantial turbulences are produced in the area of said arms, and the result is the production of a substantial sound level. It is particularly with a view to reducing the operation noise of the above-mentioned motors that, according to the invention, each arm has a straight section in the form of an aircraft wing. The principal advantage resulting from the adoption of the provisions in conformity with the invention is the obtaining of a substantial noise reduction, sought in particular in the applications made in automobile construction. The invention will be better understood, and secondary characteristics and their advantages will become clear in the course of the description of an embodiment given below as an example. It is understood that the description and drawings are given only indicatively and non limitatively. Reference will be made to the attached drawings in which: Figure 1 is a simplified axial section of an alternator embodying the invention; Figure 2 is a view along ll-ll of Figure 1; and Figure 3 is a section along Ill-Ill of Figure 2. The motor vehicle alternator represented in Figure 1 comprises: - a casing 1 comprising one rear cross plate 2 provided with air inflow openings 3 and a front cross plate 4 provided with air outifow openings 5; - a stator 6, comprising in particular a stack of magnetic sheets, fixed relative to casing 1; - a rotating shaft 7, mounted so as to rotate relative to the casing 1 by means of rear 8 and front 9 roller bearings; - a rotor 10, solid in rotation with shaft 7 and disposed inside the casing 1; - a fan wheel 11, fixed on a part of shaft 7 which projects outside the casing 1 in the vicinity of the front plate 4; - a pulley 12 which is fixed on the end of said part of shaft 7, by means of a washer 13 and a screw and nut assembly 14, and is adapted, by co-operating with a driving belt, to effect the rotational drive of the shaft 7, of the rotor 10 and of the fan wheel 11. The front plate 4 has several arms 15 which extend substantially radially and separate the various openings 5 one from the others. These arms 15 have a profiled form, in the shape of an aircraft wing (Fig.3) and are so directed relative to the axis of rotation of the rotor 10 that their section is substantially parallel with the direction D of the air outflow through the openings 5. When the rotor 10 of the alternator is driven in rotation, the fan wheel 11 creates at the front a depression which exhausts air and forces it to go through the inside of the casing 1 from the rear forward. The air flow issuing from the casing through the openings 5 moves along the arms 15 without impact and without turbulence, so that the corresponding noise is low and reduced relative to previous arrangements. The invention is not limited to the embodiment shown, but, on the contrary, covers all alternatives that may be introduced into it without departing from its framework, or its concept. CLAIMS

1. A hollow casing, supporting a rotor at least partly contained in said casing, comprising an air circulation cooling circuit, and a cross plate provided with openings separate done from the others by substantially radial arms through which the cooling air flows out of the casing, each arm having a profiled straight section and being directed in such a manner as to minimize the aerodynamic turbulence of the air exhaust, characterised in that each arm has a straight section in the form of an aircraft wing.

2. A hollow casing supporting a rotor at least partly contained in said casing, comprising an air circulation cooling circuit, and a cross plate provided with openings separated one from the others by substantially radial arms, through which the cooling air flows out of the casing, each arm having a profiled straight section and being directed in such a manner as to minimize the aerodynamic turbulence of the air exhaust, characterised by the form and the direction of the straight section of each arm such as described and represented on the drawings.

3. A hollow casing substantially as described herein with reference to the accompanying drawings.

4. An alternator comprising a rotor disposed within a hollow casing in accordance with any preceding claim.