US3687360A

US3687360A - Noise suppressing baffle discharge exit

Info

Publication number: US3687360A
Application number: US877888A
Authority: US
Inventors: Stanley R Prew; Llewelyn E Clark
Original assignee: Beloit Corp
Current assignee: Beloit Corp
Priority date: 1969-11-19
Filing date: 1969-11-19
Publication date: 1972-08-29
Anticipated expiration: 1989-08-29
Also published as: CA921834A; JPS519404B1

Abstract

A baffle, which is used in a discharge duct which removes material tangentially from a device with rotating blades such as a vertical shaft refiner or centrifuge, suppresses noise of the device and limits the product buildup on the walls of the duct. The baffle has a portion blocking part of the opening between the device and the duct with a second portion extending along the duct providing a change in the cross-section of the duct adjacent the opening. Due to the change in the cross-section caused by the baffle, material being discharged into the duct expands with a corresponding decrease in its velocity of travel to eliminate or reduce the tendency of the material to stick to the side wall of the duct to cause a product buildup.

Description

United States Patent Prew et al.

[4 1 Aug. 29, 1972 [54] NOISE SUPPRESSING BAFFLE DISCHARGE EXIT [73] Assignee: Beloit Corporation, Beloit, Wis.

[22] Filed: Nov. 19, 1969 21 Appl. No: 877,888

[52] US. Cl. ..233/46, 415/204, 138/39 [51] Int. Cl. ..B04b 11/00 [58] Field of Search .233/1, 16, 27, 28, 46, 47 R;

[56] References Cited UNITED STATES PATENTS 2,956,736 10/1960 Mayer et a1 ..4l5/204 3,034,702 5/1962 Larsson et a1 ..415/204 X FOREIGN PATENTS OR APPLICATIONS 603,418 10/1934 Germany ..415/207 Primary ExaminerJordan Franklin Assistant Examiner--George H. Krizmanich Att0meyHill, Sherman, Meroni, Gross & Simpson [5 7 ABSTRACT A baffle, which is used in a discharge duct which removes material tangentially from a device with rotating blades such as a vertical shaft refiner or centrifuge, suppresses noise of the device and limits the product buildup on the walls of the duct. The bnflle has a portion blocking part of the opening between the device and the duct with a second portion extending along the duct providing a change in the cross-section of the duct adjacent the opening. Due to the change in the cross-section caused by the baffle, material being discharged into the duct expands with a corresponding decrease in itsvelocity of travel to eliminate or reduce the tendency of the material to stick to the side wall of the duct to cause a product buildup.

5 Claims, 3 Drawing Figures BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention pertains to a baffle for a discharge duct and particularly for a baffle for a discharge duct of a tangential outlet for a machine havin g rotating members.

2. Prior Art When handling a material which is either moist or in a slurry, the material tends to accumulate in a product buildup at any point at which a change of direction of the flow of material occurs or at a point at which the flow of material is directed against a surface of the passageway. In a refiner having rotating blades or a centrifuge, the outlet duct is arranged to remove material from the refiner or device in a tangential direction. However, the size of the opening of the outlet duct enables a certain portion of the material being expelled therethrough to travel in a path which is not parallel to the axis of the duct. This results in an accumulation or product buildup of materials on the trailing wall surface of the duct which product buildup eventually chokes off or blocks the flow of materials through the duct.

Another difficulty experienced in tangential discharge ducts of a device having rotating members including blades is that due to the size of the duct opening, the trailing edge or trailing wall provides a surface which approaches a parallel relationship to the radius of the rotating members. Such an arrangement causes excessive noise in the device due to the blades rotating past a surface which is substantially radial with respect to the axis of rotation.

SUMMARY OF THE INVENTION The present invention is directed to a baffle device for an outlet duct which device reduces the noise level of the machine and reduces the buildup or accumulation on a surface of products being removed through the duct. In the preferred embodiment, the baffle device includes a portion which reduces the size of the outlet opening of the duct and which changes the crosssection of the duct adjacent to the opening into the machine.

Accordingly it is an object of the present invention to provide a baffle in a discharge duct which suppresses noise of the machine.

Another object of the present invention is to provide a baffle in the discharge duct of a machine having tangential removal of material which reduces the accumulation of material on the walls of the discharge duct.

Other objects, features and advantages of this invention will be readily apparent from the following description of the preferred embodiment taken together in conjunction with the accompanying drawings although variations and modifications may be effected without departing from the scope and spirit of the novel concepts of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a plan elevational view of a duct utilizing the baffles of the present invention;

FIG. 2 is a cross-section taken along lines II-II of FIG. 1; and

FIG. 3 is a view taken along the lines III--III with portions in elevation for purposes of illustration.

DESCRIPTION OF THE PREFERRED EMBODIMENT Although the principles of the present invention are of utility for preventing product buildup and reducing noise for any discharge duct, the principles are particularly useful when incorporated in a tangential discharge duct for a machine having rotating members which duct is illustrated in FIG. 2 and generally indicated at 10.

The duct 10 is illustrated as being mounted on a housing 11 of a device having a substantially cylindrical inner peripheral surface 12 defining a cylindrical chamber for receiving rotating members with blades (not illustrated). The rotating members in the housing I 1 rotate in a direction of the arrow 13 and the duct has a leading wall 14 which extends tangentially to the periphery of the inner cylindrical surface 12 of the housing 11. The duct 10 is substantially rectangular in cross-section and has a trailing wall 15 which is substantially parallel to the wall 14 and a pair of

parallel side walls

16 and 17 which walls forming with the housing 11 having an opening 18 having a trailing edge 24 which leads from location 25 back to location 19.

Since the trailing wall 15 is parallel to the leading wall 14, the trailing wall 15 at location 19 is not in a tangential relationship to the cylindrical surface 12 or to the flow of material discharged adjacent location 19. Thus, material being discharged tangentially to the cylindrical wall 12 at a point midway between the leading wall 14 and the trailing edge or wall 15 is projected at an angle to the axis of the duct 10 and against the trailing wall 15 and this material tends to accumulate on the surface of the wall 15.

Since the trailing wall 15 is parallel and spaced from the leading wall 14, the trailing wall 15 forms an acute angle. As mentioned above, in usual structures heretofore available, the blade on the rotational member disposed in the chamber had a substantial parallel relationship to an axially extending edge positioned at location 19 and this relationship increased the noise level of the machine or device.

The present invention provides a baffle means generally indicated at 21 disposed in the interior of the duct 10 adjacent to the trailing wall 15. As illustrated, the baffle means 21 comprises a pair of

plate members

22 and 23 with the plate member 22 being triangular in configuration and having a curvature which is substantially the same as the curvature of the cylindrical surface 12 of the housing 11. The plate 22 extends from the trailing location 19 of the opening 18 and blocks or closes a portion of the opening 18 to form an effective opening. The plate 22 has a leading edge 24 to which the second plate member 23 is joined. As illustrated, the second plate member 23 extends from the leading edge 24 of the curved plate member 22 and extends at an angle to an axis of the duct 10 to merge or be attached to the trailing wall 15 and a side wall 16 of the duct 10. The position of the plate member 23 in the duct 10 causes a reduction in the cross-sectional area of the duct 10 adjacent the opening 18 and the amount of the reduction of cross-sectional area gradually decreases as the distance along the duct 10 from the opening 18 decreases. The position and the configuration of the baffle means 21 restricts the size of an opening 18 and causes a gradual change of the cross-sectional area of the duct adjacent the opening 18. Thus materials expelled through the opening 18 into the duct 10 gradually expands with a decrease in the velocity which is beneficial and removes one of the causes for a buildup or accumulation of the product on the walls of the duct. Also, the configuration and position of the plate member 23 decreases the angle of incidence which material discharged tangentially to the opening into the duct 10 strikes a surface of the duct and reduces the tendency for the material to stick or adhere to the wall surfaces. The position of the plate 22 also changes the efiective relationship of the trailing wall surface to the passing blades of the rotating member and causes a reduction or suppression in the noise level of the device.

In the preferred embodiment and best illustrated in FIG. 3, the baffle means 21 is disposed with the leading edge 24 of the plate member 22 extending across the opening 18 at an acute angle to the plane which is perpendicular to the axis of rotation of the rotating members and blades in the housing 11 and to the axis of the cylindrical inner peripheral surface 12 which planes are substantially parallel to

walls

16 and 17. Due to this disposition, the effective opening formed by the plate 22 in the opening 13 has its maximum size adjacent to the leading wall 14, which forms a leading edge of the opening and is gradually reduced starting at point as the arcuate distance from the wall 14 toward the trailing edge 19 increases. In other words, the leading edge 24 of the plate member 22 may also be called the trailing edge of the effective opening of the housing with respect to the direction (arrow 13) of movement of the rotating blade member. Thus, the plate 22 reduces the amount of material being discharged tangentially from the chamber formed by the cylindrical surface 12 as the blades move past point 25. Such a reduction of material causes a reduction in the amount of material which tends to be deposited on the wall surface 15. As illustrated, the member 23 is triangular in configuration and has a leading edge attached to the leading edge 24 of the member 22 and the remaining two edges attached to the side wall 16 and trailing wall 15 respectively. The plate member 23 preferably fiat or planar and the remaining two edges define a point 26 which is disposed in a corner 27 between the

walls

15 and 16.

As mentioned hereinabove, the noise level increases in the machine when the blades and the trailing edge wall of a duct approaches a parallel configuration. With the addition of the baffle means 21, the angle of the trailing wall surface or its effective configuration caused by the plate 23 is closer to a tangential relationship with the blade as the blade moves across the opening towards the trailing edge 19. Thus, the baffle 21 removes the relationship of the trailing edge wall and the blades which causes the excessive noise in the system and provide a relationship between the trailing wall surface and blades that promote noise suppression.

As illustrated, the duct 10 has a substantially rectangular cross-section and the provisions of the baffle means 21 changes the effective shape of the opening 18 of the duct into the chamber formed by the cylindrical surface 12 to be substantially trapezoidal. A baffle means similar to means 21 could be utilized with a duct having a circular cross-section with appropriate changes in the configuration or shape of the plate 22 to provide for closing a portion of the substantially circular opening and in the plate 23 for attachment of the upper edge to a curved surface of the circular duct.

The baffle means 21 reduces the tendency of product buildup on the walls of the duct by changing the configuration of the opening, by providing a gradual increase in the cross-sectional area of the duct with a corresponding decrease in the velocity of the product being discharged through the duct 10, and by changing the angle of incidence of material striking a surface of the duct as the material travels tangentially through the opening 18 to reduce the tendency of sticking to a surface of the duct. The baffle means 21 also suppresses noise in the device by changing'the configuration and relationship of the trailing surface of the duct that the blades move past.

Although minor modifications might be suggested by those versed in the art, it should be understood that we wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of our contribution to the art.

We claim as our invention:

1. In a device having a housing with a substantially cylindrical inner periphery for receiving a rotating member and a tangential discharge duct forming a discharge opening for said housing, the improvement comprising means reducing the buildup of products removed through said duct on the wall surfaces thereof and reducing the noise of the operation of said device, said means including a baffle member disposed in said opening to block a portion thereof, said baffle member including a first surface closing a portion of the opening forming an effective opening and a second surface extending from said first surface along said duct, said second surface extending from a leading edge, of the first surface at an angle to the axis of the duct and merging with the wall of said duct forming a cross-sectional area of the duct which increases along the duct from said effective opening, the leading edge of said second surface forming an acute angle with a plane extending perpendicular to the axis of the cylindrical inner periphery of the housing.

2. In a device constructed in accordance with claim 1 wherein said discharge duct is rectangular in shape and wherein said second surface is triangular in shape and is disposed in a corner of said duct at said discharge opening with its leading edge causing the effective opening to be trapezoidal in shape.

3. In a device constructed in accordance with claim 1 wherein said first and second surfaces are formed by plates mounted in the discharge opening.

4. in a device constructed in accordance with claim 1 wherein the cross-sectional area of the discharge duct increases outwardly of the opening with the direction of the increase in the area extending toward one side of the housing.

5. in a device constructed in accordance with claim 1 wherein said surfaces are formed by plates with the plate forming the first surface having a curvature substantially the same as the curvature of the cylindrical inner periphery of the housing.

Claims

1. In a device having a housing with a substantially cylindrical inner periphery for receiving a rotating member and a tangential discharge duct forming a discharge opening for said housing, the improvement comprising means reducing the buildup of products removed through said duct on the wall surfaces thereof and reducing the noise of the operation of said device, said means including a baffle member disposed in said opening to block a portion thereof, said baffle member including a first surface closing a portion of the opening forming an effective opening and a second surface extending from said first surface along said duct, said second surface extending from a leading edge of the first surface at an angle to the axis of the duct and merging with the wall of said duct forming a cross-sectional area of the duct which increases along the duct from said effective opening, the leading edge of said second surface forming an acute angle with a plane extending perpendicular to the axis of the cylindrical inner periphery of the housing.