Air cooled gear housing

A spur-gear mechanism, especially a bevel spur-gear mechanism, having one or more transmission stages is provided. The transmission stages are accommodated in a gear mechanism housing having two side surfaces and two base surfaces. Guided out of the gear mechanism housing is a drive shaft on which is fixedly secured, beyond a housing, an axial fan wheel. A spacer flange for connection to a motor spacer is formed on the gear mechanism housing. The spacer flange is provided with central openings in an extension of the base surfaces and with lateral openings in an extension of the side surfaces.

BACKGROUND OF THE INVENTION

The present invention relates to a spur-gear mechanism, especially a bevel spur-gear mechanism, having one or more transmission stages.

Gear mechanisms having a bevel gear stage are a generally known structural approach in order, in addition to the important mechanical values of speed and torque, to also alter the spatial position between the drive shaft and the output shaft. The axes of the drive shaft and the output shaft are customarily offset relative to one another by an angle of 90°. Particularly economical is the use of the bevel gear set as the first stage in a generally multi-staged gear mechanism. In particular for drives of conveyor belt units, bevel spur-gear mechanisms enable the parallel alignment of drive and conveyor belt unit.

With a minimal number of individual components, a universal gear mechanism series can be produced that encompasses many structural sizes. The individual components are technically designed in an optimum characteristic curve. Due to the high reproducing frequency of individual components in various variations, this concept additionally has special economical advantages.

There exists for a plurality of comparable gear mechanism series according to the mechanical assembly technique a program that includes not only spur-gear mechanisms but also bevel spur-gear mechanisms. The gear mechanisms are available for all conceivable installation positions and with different types of constructions of the drive and output shafts. Characteristic is the use of an extensively unaltered base housing not only for the spur-gear mechanism but also for the bevel spur-gear mechanism. Alternatively, further auxiliary components, such as block or return lockings and brakes are also available.

Derived from the existing program are product programs that are adapted for special branch strong points and that utilize the advantages of the existing universal structural series, and which at the same time are limited to the assembly of branch-conventional variants. For conveyor belt drives, essentially two-stage and three-stage bevel spur-gear mechanisms are used. For three-stage bevel spur-gear mechanisms, a special variant having a surface of the gear mechanism housing that is enlarged by cooling ribs is also provided.

The drawback of the concept of a universal mechanical assembly gear mechanism is, for branch-specific applications, the prevailing use of identical components. This includes, in particular, the gear mechanism housing. In addition to the mechanical stress, the thermal limiting output is a determinative design criterion for conveyor belt drives. Since in general in surface working or mining, or similar applications, no cooling water is available for the conveyance of loose material, and the use of other cooling and lubricating means, such as oleo or oil/air coolers, is not possible for various reasons, the entire gear mechanism heat must be given off to the air via convection. In addition, the raw environmental conditions that exist at the use site in question, and which have a high occurrence of dust, make the maintenance of the heat withdrawal more difficult, since dust layers that are deposited on the gear mechanism housing have an insulating effect. Known in this connection are bevel spur-gear mechanisms having a housing surface that is enlarged by cooling ribs, and having an axial fan wheel disposed on the drive shaft.

It is an object of the present invention to alter the bevel spur-gear mechanism of the aforementioned general type for use as a conveyor belt drive in such a way that under specific optimization of the housing form, the quantity of heat that is carried off by convection can be permanently increased.

SUMMARY OF THE INVENTION

The spur-gear mechanism of the present application comprises a gear mechanism housing that surrounds the transmission stages and is provided with two side surfaces and two base surfaces, wherein cooling ribs are disposed on the side surfaces and the base surfaces; an axial fan wheel fixedly disposed on a drive shaft externally of the gear mechanism housing; and a spacer flange for connection to a motor spacer, wherein the spacer flange is formed on the gear mechanism housing, and wherein the spacer flange is provided with central openings in an extension of the base surfaces and with lateral openings in an extension of the side surfaces.

Further specific features of the present application will be described in detail subsequently.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Referring now to the drawings in detail, illustrated inFIG. 1is a spur-gear mechanism that is embodied as a bevel spur-gear mechanism1. The bevel spur-gear mechanism1is provided with an upper housing portion2and a lower housing portion3, which have a symmetrical configuration and can be cast in the same mold. The engagement of the drive is, in the illustrated embodiment, effected by the connection of the output shaft4to a non-illustrated unit, which is preferably a conveyor belt unit for conveying loose or bulk material. The output shaft4is embodied as a solid shaft, and is connected via a non-illustrated flange coupling to a work machine of the unit. Alternatively, where a hollow shaft is used, the drive is embodied as an extension or insertion means. The drive power passes into the gear mechanism from a non-illustrated drive motor via a drive shaft5.

The drive shaft5is a part of the bevel gear stage of the gear mechanism. Due to the low mechanical stressing that occurs in the first transmission stage, the relatively expensive to manufacture bevel gear toothing is provided at the input side. The drive shaft5projects out of the end face of the gear mechanism housing, and is supported in a housing core6that is connected with the gear mechanism housing. Disposed on the housing core6, in the direction of the shaft input, is a spacer flange7for the connection of a motor flange; the spacer flange will be described in greater detail subsequently. Reinforcing ribs8are secured in a vertical plane to the upper and lower side of the housing collar6. The reinforcing ribs8are provided with pivot or wrist or knuckle points9for the connection of a pivotable torque support means.

Mounted on both sides of a horizontal parting line10are housing collars11,12that extend about the upper housing portion2and the lower housing portion3. The housing collars11,12form flange-like projections that serve for receiving housing screws13, via which the upper housing portion2and the lower housing portion3are bolted to one another.

Disposed in the side surfaces16,17of the upper housing portion2and of the lower housing portion3are bosses or hubs for receiving the shafts of the transmission stages and the output shaft. As do the housing collars11,12, these hubs project out of the side surfaces16,17and offer the required installation space for further housing screws between the transmission stages. The hubs are closed off by a closed housing cover14, while the hub of the output shaft4is covered by an open housing cover15.

Alternatively, the closed housing cover14can be replaced by an open housing cover in order to be able to use extended shafts of the intermediate stages. Possible auxiliary units, such as, for example, an auxiliary drive, a back stop or a speed monitor, can then be connected thereto.

Cooling ribs18,19are disposed on the side surfaces16,17of the upper housing portion2and of the lower housing portion3; these cooling ribs extend parallel to one another over the entire length of the gear mechanism housing. The cooling ribs18,19increase the surface of the housing and improve the thermal transfer from the gear mechanism to the environment.

On the sides opposite the parting line10, the upper housing portion2is closed off by a base surface20, and the lower housing portion3is closed off by a base surface21. Provided on the base surfaces20,21are feet22that during the manufacture serve as alignment surfaces, and during transport and assembly serve as housing feet. For a gear mechanism having feet, there are located at these location the receiving points of the base screws.

The spatial illustration of the bevel spur-gear mechanism1ofFIG. 2clearly shows the inventively improved air stream guidance. The base of the spacer flange7is provided with lateral openings23and central openings24, which pass through the spacer flange7on both sides of a horizontal central plane in the longitudinal direction of the gear mechanism. The inner edge of each of the lateral openings23is disposed in the extension of the side surfaces16,17, and the inner edges of each of the central openings24are disposed in the extension of the base surfaces20,21of the gear mechanism housing. Only with the procedural engineering control of the casting technology of expensive components having very different material distribution in this considerable spatial extension is the direct, positive connection of the spacer flange7to the housing collar6of the bevel spur-gear mechanism1made possible. By forming the spacer flange7on the housing collar6, the latter, together with the upper housing portion2and the lower housing portion3, respectively form one component and thus represent a portion of the gear mechanism housing. As a consequence of this advantageous configuration, the gear mechanism is shorter.

Via the openings23,24the air flows out of the motor spacer connected to the spacer flange along all sides (side surfaces16,17, base surfaces20,21) of the bevel spur-gear mechanism1. To achieve an adequate rigidity of the construction of the spacer flange7, two reinforcing ribs8are mounted between the lateral openings23and the central opening24. At the same time, the reinforcing ribs8form a flow channel25(seeFIG. 3) that conveys the air along the base surfaces20and21.

The upper base surface20and the lower base surface21are advantageously inclined in a direction toward the central openings24in the spacer flange7, as a consequence of which slopes26result that represent the continuation of the flow channel25. Mounted on the base surfaces20,21are cooling ribs27to improve the thermal transfer. Even for the situation where the gear mechanism, having a foot configuration, rests directly on the ground, the slope26permits the guidance of air through below the gear mechanism.

Not only does air flow through the central openings24, but it also flows through the lateral openings23along the cooling ribs18,19of the side surfaces16,17. The cooling ribs18,19extend via a slight bend toward the lateral openings23of the spacer flange7, and are thereby adapted to the air flow in the direction of the housing collar6. By means of this slight bend, the air stream is conveyed to the end of the overall side surfaces16,17of the gear mechanism housing.

The continuous air stream guidance without abrupt jumps or transitions at all delimiting or outer surfaces (side surfaces6,17,20,21) leads to a distinctly improved thermal transfer to the air of the environment or atmosphere due to forced convection. In addition, the guided air stream prevents the dust that is always present in the surrounding air from being deposited on the gear mechanism housing and forming insulating dirt nests or pockets.

In contrast to the inventive gear mechanism housing, the housing molds of the known universal gear mechanisms for a conveyor belt drive must also take into consideration the requirements of other applications. This compromise leads to a poor heat balance, which in this application leads to an uneconomical over-dimensioning of the drive.

The illustration of the further embodiment inFIG. 3shows the overall drive train of a conveyor belt drive using a bevel spur-gear mechanism1. The gear mechanism housing is supported on a base or a machine frame via a torque support means28, which engages in the wrist or knuckle points9of the reinforcing ribs8.

The drive shaft5of the bevel spur-gear mechanism1is connected via a brake32and a fluid coupling33with the output shaft of an electric motor34that serves as a drive means. The electric motor34is flanged to the gear mechanism housing via a motor spacer31and the spacer flange7. The motor spacer31is designed for the connection of the electric motor34, which is embodied as a flange motor. Since the motor spacer31must transfer considerable weight forces to the drive bearing at the output shaft4, here also, via the spacer flange7that is cast on the housing collar6of the gear mechanism housing, a shortened connection of gear mechanism housing and electric motor34is an advantageous structural approach.

Directly following the spacer flange7, an axial fan wheel29is fixedly secured directly to the drive shaft5of the bevel spur-gear mechanism1. The motor spacer31is provided with adequately large air inlet openings35. For operational reliability, these air inlet openings35are provided with here not illustrated components to protect against engagement or access, or with dust-deflecting hoods. The axial fan wheel29which is mounted directly on the drive shaft5rotates with the high motor speed. As a result, the conveyance of a large air stream is ensured in every operating state. This air stream passes through the openings23,24in the spacer flange7, and is guided along the cooling ribs18,19,27at the side surfaces16,17, and the base surfaces20,21.

The effect of the air flow can be further increased by the use of an air-conducting hood30, which surrounds the housing collar6following the spacer flange7. The inner diameter of the air-conducting hood30is slightly greater than the radially greatest dimensions of the openings23,24in the spacer flange7. Thus, the overall air flow, in an annular channel between housing collar6and air-conducting hood30, is guided directly and with little loss to the warmest locations at the side surfaces16,17and base surfaces20,21.

The specification incorporates by reference the disclosure of German priority document 10 2004 030 180.8 filed Jun. 22, 2004.