Temperature control for blast wheel housing

Abstract

The temperature of the chamber housing a shot wheel of a shot blaster is controlled by positioning a fan exterior to the chamber that creates air flow across a mounting plate defining the chamber. The air flow created by the fan may also pass around the bearing surrounding the drive shaft that turns the shot wheel.

Claims

1. A shot blaster comprising: a. a plenum coupled to a first end of a vacuum tube and comprising a hopper and a blast wheel housing, said blast wheel housing defining an interior chamber, said blast wheel housing comprising a mounting plate, at least one wall, and a first direct vent extending through said at least one wall providing a direct airflow path from the interior chamber to the outside of the shot blaster, said mounting plate comprising an interior surface facing the interior chamber, an exterior surface, and a drive shaft orifice, said at least one wall comprising an interior surface facing the interior chamber and an outer surface external to the shot blaster; b. a blast wheel coupled to a drive shaft, said blast wheel positioned within the interior chamber of the blast wheel housing and said drive shaft extending from the blast wheel through the drive shaft orifice; c. a bearing mounted to the exterior surface of the mounting plate, surrounding a portion of the drive shaft, and closing the drive shaft orifice; d. a first motor coupled to the drive shaft; e. a second wall extending away from said blast wheel housing from the exterior surface of the mounting plate, a vent extending through said second wall, said vent adapted to provide airflow to dissipate heat conducted through the mounting plate from the interior chamber; and f. a liner adapted to isolate said first direct vent from shot flying off the blast wheel to prevent shot from exiting the housing through said first direct vent.

2. The shot blaster of claim 1 further comprising a fan adapted to provide airflow across the exterior surface of the mounting plate and around the bearing.

3. The shot blaster of claim 1 further comprising a fan adapted to provide airflow through said vent.

4. The shot blaster of claim 1 further comprising a fan adapted to provide airflow through said direct vent.

5. A shot blaster comprising: a. a plenum coupled to a first end of a vacuum tube and comprising a hopper and a blast wheel housing, said blast wheel housing defining an interior chamber, said blast wheel housing comprising a mounting plate, and at least one wall, and a first direct vent extending through said at least one wall providing a direct airflow path from the interior chamber to the outside of the shot blaster, said mounting plate comprising an interior surface facing the interior chamber, an exterior surface, and a drive shaft orifice, said at least one wall comprising an interior surface facing the interior chamber and an outer surface external to the shot blaster; b. a blast wheel coupled to a drive shaft, said blast wheel positioned within the interior chamber of the blast wheel housing and said drive shaft extending from the blast wheel through the drive shaft orifice; c. a bearing mounted to the exterior surface of the mounting plate, surrounding a portion of the drive shaft, and closing the drive shaft orifice; d. a first motor coupled to the drive shaft; and e. a liner adapted to isolate said first direct vent from shot flying off the blast wheel to prevent shot from exiting the housing through said first direct vent.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, especially when considered in conjunction with the accompanying drawings in which like numerals in the several views refer to corresponding parts:

(2) FIG. 1 is a side view of a shot blaster;

(3) FIG. 2 is a cross-sectional view showing the blast wheel within a housing and an embodiment of the temperature control mechanism of the present invention;

(4) FIG. 3 is an alterative view of the temperature control mechanism of FIG. 2; and

(5) FIG. 4 is a cross-sectional view of an alternative embodiment showing the blast wheel housing directly vented with a fan inside.

DESCRIPTION OF THE PREFERRED EMBODIMENT

(6) This description of the preferred embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. In the description, relative terms such as “lower”, “upper”, “horizontal”, “vertical”, “above”, “below”, “up”, “down”, “top” and “bottom” as well as derivatives thereof (e.g., “horizontally”, “downwardly”, “upwardly”, etc.) should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms such as “connected”, “connecting”, “attached”, “attaching”, “join” and “joining” are used interchangeably and refer to one structure or surface being secured to another structure or surface or integrally fabricated in one piece, unless expressively described otherwise.

(7) A self-propelled shot blasting machine 1 is shown in FIG. 1. The machine 1 sits on a pair of rear wheels 10 and a front drive wheel 12.

(8) Machine 1 is driven by an electric motor 11 coupled to drive wheel 12. The machine 1 has a second motor 13 that drives a blast wheel 14.

(9) The machine 1 also has a plenum 20 incorporating a hopper 22 and a housing 23 surrounding the blast wheel 14. The plenum 20 is coupled to one end of a vacuum tube 24 by a fitting (or port) 25. The other end of the vacuum tube 24 is coupled to a vacuum (not shown).

(10) Hopper 22 is filled with shot prior to use. The vacuum is then energized to create air flow through the vacuum tube 24 and plenum 20. The motors 11 and 13 are then energized. Energizing motor 13 causes the blast wheel 14 to spin. Shot is metered from hopper 22 through a valve into the housing 23 where the blast wheel 14 is located. The blast wheel 14 accelerates the shot toward a spout opening 28 at the base of the housing 23 adjacent the floor and in an area contained by a suction head 26. As the shot impacts the floor's surface roughening the surface, the shot, together with floor debris and dust, are carried through the plenum 20 by the air flow. The dust and debris are carried to the vacuum. The shot is deposited back into the hopper and recycled.

(11) Operation of the two motors 11 and 13 and the speed and direction of the machine are controlled by ergonomic controller 30.

(12) The housing 23 has an interior chamber 52 in communication with spout opening 28. The housing 23 comprises a mounting plate 54 having an interior surface 56 facing the interior chamber 52, an exterior surface 58, and a drive shaft orifice 60.

(13) A blast wheel 14 is coupled to a drive shaft 62 and positioned within the interior chamber 52 of the housing 23. The drive shaft 62 extends from the blast wheel 14 through the drive shaft orifice 60. A bearing 64 is mounted to exterior surface 58 of the mounting plate 54. The bearing 64 surrounds a portion of the drive shaft 62 and encloses the drive shaft orifice 60. Motor 13 is coupled to the drive shaft 62. Various elements may be employed to couple the drive shaft 62 to the motor 13, for example a chain and a pair of sprockets, or a belt and a pair of pullies. In any case, the motor 13 turns the drive shaft 62 which, in turn, drives the blast wheel 14.

(14) A fan 70 is mounted outside of the interior chamber 52. The fan is 70 directed to create airflow across the exterior surface 58 of the mounting plate 54 and around the bearing 64. This fan dissipates heat from the interior chamber 52. More specifically, the air passing over the exterior surface 58 of the mounting plate 54 and around the bearing 64 draws heat away from these structures creating a greater temperature differential that causes heat from inside of the interior chamber 52 to be transmitted to the outside through the mounting plate 54 and bearing 64.

(15) In some embodiments, the housing has at least one wall 72 extending at an angle from the mounting plate 54 adjacent the bearing 64. Such a wall may be present for various reasons, for example to reinforce the shot blaster assembly generally or to support specific structures of the assembly. In some cases, the wall 72 will be positioned between the motor 13 and the bearing 64. When so positioned, the wall 72 directs heat generated by the motor 13 away from the area of the immediately adjacent the interior chamber 52 of the housing 23. The wall 72, no matter where positioned, may include one or more vents 74/75 that cooperate with the fan 70.

(16) The fan 70 has a suction side and a discharge side. The location of the wall 72 will dictate whether the suction side or discharge side of the fan 70 should face the vent(s) 74. When the suction side faces toward the vent(s) 74, air passes through the vents 74 before reaching the fan 70 and being blown by the fan 70 across the mounting plate 54 and around the bearing 64. This arrangement may be preferred when the wall is not between the motor and the bearing. When the wall 72 is between the motor 13 and the bearing 64, it may be preferable to position the discharge side of the fan 70 toward the vent(s) 74.

(17) The fan 70 includes a blade 76 and some means to rotate the blade to create airflow. In most cases, the fan 70 will comprise a blade driven by an additional motor. However, the blade could also be driven by motor 13 without deviating from the invention. For example, the fan 70 could be mounted to the drive shaft 62 to which the blast wheel 14 is mounted or to a separate drive shaft also driven by the motor 13. For safety reasons the fan blade will typically reside in an enclosure 77 that does not unduly impede air flow generated with the fan.

(18) FIG. 4 shows an alternative embodiment of the present invention. This embodiment includes modifications to the blast wheel housing 23. Specifically, vents 80 and 81 have been added to the exterior walls of the blast wheel housing to provide air flow through the interior chamber 52 of the blast wheel housing 23. The blast wheel housing has been further modified to include a liner 84 between the blast wheel 14 and the vents 80 and 81.

(19) The liner 84 may be an imperforate metal sheet. When this is the case, only the region of the interior chamber 52 of blast wheel housing 23 between the liner 84 and the vents 80/81 is directly vented. Heat generated in other parts of the interior chamber 52 is dissipated via conduction through the liner 84 and then carried out of the housing 23 by air flow through vents 80/61. This airflow may be enhanced by employing a fan 82. Fan 82 is shown positioned within the interior chamber 52 of blast wheel housing 23 adjacent vent 81. The liner 84 separates the fan 82 from the blast wheel 14. As such, the liner 84 isolates and protects the fan 82 (and the vents 80/81) from shot flying off the blast wheel 14. The fan 82 could also be mounted outside of the housing 23 adjacent one of the vents 80/81 to make assembly easier.

(20) For even greater air flow through the housing 23, the liner 84 may be semi-permeable. Specifically, the liner 84 may be formed as a mesh with pores large enough to permit air to pass through the liner 84 and small enough to prevent shot or other particles flying off the blast wheel from passing through the liner 84.

(21) As noted above and shown in FIG. 1, the blast wheel housing 23 is part of (or at least in fluid communication with) the plenum 20. The plenum 20 is coupled to a vacuum tube 24 which is attached to a vacuum (not shown). When the vents 80/81 are provided, the liner is semi-permeable and the vacuum is energized, the vacuum will draw air in through the vents 80/81, the liner 84, and the rest of the interior chamber 52. This air will exit the interior chamber 52 through the spout opening 28. The fan 81 may again be provided to enhance such air flow through the interior chamber and out the spout opening 28.

(22) The embodiments shown in FIGS. 2 and 4 may, of course, be combined to enhance cooling and heat dissipation from the interior chamber.

(23) In such cases, direct vents such as 80/81 are provided and indirect vents such as 74/75 are provided. As used herein, a “direct vent” is a vent that provides a flow path for air between the exterior of blast wheel housing 23 and the interior chamber 52; and an “indirect vent” is a vent that provides a flow path for air across exterior walls of the blast wheel housing 22 or other exterior structures associated with housing 23 that will conduct heat from the interior chamber 52 of blast wheel housing 23. Fans such as 82 may be provided to enhance air flow through the direct vents 80/81 and fans such as 70 may be provided to enhance air flow through the indirect vents 74/75.

(24) This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use embodiments of the example as required. However, it is to be understood that the invention can be carried out by specifically different devices and that various modifications can be accomplished without departing from the scope of the invention itself.