GB2095330A

GB2095330A - Air-compressor unit

Info

Publication number: GB2095330A
Application number: GB8207873A
Authority: GB
Original assignee: MAN Maschinenfabrik Augsburg Nuernberg AG
Current assignee: MAN AG
Priority date: 1981-03-21
Filing date: 1982-03-18
Publication date: 1982-09-29
Also published as: DE3111258A1; GB2095330B; CH655977A5; FR2502371A3; IT8219883A0; FR2502371B3; BE892250A; IT1149782B

Abstract

The unit comprises a housing 1, 14 accommodating a compressor 2 of e.g. the screw type, and an electric motor 3, which is air-cooled internally by a fan 4. The housing includes separate openings 5, (8), Fig. 2 (not shown), for compressor feed air and motor cooling air the compressor feed air respectively being conducted through a sound-damped channel (6) containing a filter (7) and producing at least one deflection of the air stream through 180 DEG , and the motor cooling air being inducted by the fan 4. The surplus air at the compressor is discharged together with the exhaust cooling air through a silencer or sound damper 11, which deflects the air stream through 180 DEG . Transmission of vibrations from the compressor and motor to the housing is reduced by "dampers" 15. <IMAGE>

Description

SPECIFICATION Compressor Unit The present invention relates to a sounddamped compressor unit, and has particular reference to a unit comprising a housing in which an internally cooled electric drive motor and a compressor with ancillary equipment are arranged.

Compressor units are known, which comprise a housing containing a compressor with oil injection and drive motor, a fan wheel being arranged between the compressor and motor. The fan wheel, as the main noise generator, is in that case arranged within the housing of the unit between an inlet and an outlet opening in about the middle of the flow path of the cooling air, so as to provide the longest possible damping path for the sound waves.

In these sound-damped units, the sound level is already reduced through construction of the compressor to be cooled by oil injection.

However, compressor units of this kind with a dry-running compressor cause a noise level which can exceed the permissible limit.

There is accordingly a need for improvement in the sound damping of housed compressor units with compressor and drive motor, without complication of the mode of construction at the same time. The noise output should preferably lie appreciably below legally prescribed limits, so that an appreciable improvement in ergonomic conditions results.

According to the present invention there is provided a sound-damped compressor unit comprising a compressor, an electric motor drivingly coupled to the compressor and provided with an internal cooling fan and with a silencer for exhausted cooling air, a housing enclosing the compressor and motor and being provided with respective inlets for air to be compressed by the compressor and for cooling air inducted by the fan, sound-insulating inlet duct means for conducting air to the compressor from the respective inlet, the inlet duct means being arranged to deflect the conducted air at least once through substantially 1 BOO and incorporating an air filter, outlet duct means for conducting compressed air from the compressor into the silencer, the outlet duct means being arranged to deflect the conducted compressed air through substantially 1 800, and insulating means for insulating the housing against transmission thereto of sound generated by the compressor and the motor.

In a preferred embodiment, separate openings for compressor and motor feed air are arranged in the housing, and the air conduction is so arranged that the compressor air is conducted through a sound-insulating channel with integrated filter and with at least one deflection through 1800 and the motor feed air is inducted by the internal fan of the motor. The relief air of the compressor is conducted away with a deflection through 1 800 in the same direction as the motor exhaust air through the sound damper of silencer of the motor, and the housing, in the form of a sound box consisting of a basic frame and cladding, is insulated against sound conduction from the compressor and motor.

The outlet duct means from the compressor is preferably conducted through a deflecting member in the form of an inflow pipe and two arcuate outflow pipes. The relief air of the compressor can then be fed to the motor exhaust air silencer or sound damper in the same direction as the exhaust air. In this manner, the report following relief of the compressor is damped to the largest extent and an additional sound damper can thus be dispensed with.

The construction of the common exhaust air conduction has the advantage that the motor exhaust air is entrained in the manner of an injector by the deflected compressor relief air, whereby the internal fan of the motor in its turn is relieved.

The internal fan of the motor can be further relieved by dimensioning the feed and exhaust air channels to be relatively large in order to keep the flow resistance small.

The housing of the compressor unit preferably comprises sound-absorbing material and is composed of individual elements so that only selected ones of these elements need be tilted away or removed for repair and maintenance operations.

An embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which Fig. 1 is a schematic longitudinal sectional view of a sound-damped compressor unit according to the said embodiment; and Fig. 2 is a plan view of the unit of Fig. 1.

Referring now to the drawings, there is shown a compressor unit comprising a screw compressor 2 and an electric drive motor 3 arranged one behind the other on a basic frame 14 in an elongate housing, which is rectangular in cross-section and comprises sound-absorbing material. The drive motor may be a commercially available motor with an internal fan 4.

Feed air for the compressor 2 is inducted through an opening 5 in an end face of the housing. This air passes through a sound-damped channel 6 and is deflected twice through 1 800 on its way to the compressor. Incorporated behind the first 1800 deflection is a feed air filter 7, which after folding up of the appropriate housing element is readily accessible and easily exchangeable, even during operation.

The feed air, i.e. cooling air, for the motor 3 is drawn by the internal fan 4 through two feed air openings 8 and through sound damping channels (not shown) into the housing.

This feed air can, if desired, be cleaned by a filter (not shown in this embodiment).

The compressor relief air is conducted through a duct 9 and a deflecting member 10 with deflection through 1 800 , into an exhaust air duct of the motor and then is conducted in the same direction over the shortest path with the motor exhaust air through a silencer or sound damper 11 and through two exhaust pipes 12 into the open.

A switch box 13 is mounted in a region of the housing 1 where it will not be subjected to warm air.

The drive motor 3 and compressor 2 are decoupled by oscillation dampers 15 from the housing, which is in the form of a sound box consisting of a basic frame 14 and housing cladding 1. Of course, means are provided to effect an oscillation decoupling between the housing and the feed and exhaust air ducts.

By dispensing with an externally disposed fan for the cooling of the drive motor, and through the described formation of the feed and exhaust air channels, together with the provided insulation against conducted sound, an optimum noise damping of the compressor unit takes place. The pulsating suction noises of the compressor i.e. the sound passage to the air induction opening in the housing, are largely absorbed by the sound damping channel provided with at least one deflection.

Claims

1. A sound-damped compressor unit comprising a compressor, an electric motor drivingly coupled to the compressor and provided with an internal cooling fan and with a silencer for exhausted cooling air, a housing enclosing the compressor and motor and being provided with respective inlets for air to be compressed by the compressor and for cooling air inducted by the fan, soundinsulating inlet duct means for conducting air to the compressor from the respective inlet, the inlet duct means being arranged to deflect the conducted air at least once through substantially 1 800 and incorporating an air filter, outlet duct means for conducting compressed air from the cdmpressor into the silencer, the outlet duct means being arranged to deflect the conducted compressed air through substantially 1 800, and insulating means for insulating the housing against transmission thereto of sound generated by the compressor and the motor.

2. A compressor unit as claimed in claim 1, wherein the housing comprises a basic frame provided with cladding to form a sound box.

3. A compressor unit as claimed in either claim 1 or claim 2, the outlet duct means comprising a duct section leading into the silencer and two curved outflow duct sections connected to the first-mentioned duct section to guide the compressed air out into the silencer.

4. A compressor unit substantially as hereinbefore described with reference to the accompanying drawings.