Random orbit sander having air directing baffle

Abstract: An air directing baffle for a random orbit sander 10 includes a main body portion 58 forming an annular opening 60, a pair of neck portions 62 extending approximately circumferentially opposite from one another, and a pair of recessed portions 64 formed in each of the neck portions. The neck portions extend into airflow registration with a plurality of exhaust slots 32 formed in a shroud 18 rotatably disposed at a lower portion 16 of a housing 12 of the sander. The annular opening is adapted to fit over a boss 68 portion protruding from a lower face surface 70 of the housing of the sander to thus permit the baffle to be rotated freely relative to the housing. The recessed portions in each of the neck portions of the baffle inwardly engage with a pair of inwardly protruding shoulder portions 66 formed in an interior area of the shroud. The interengagement of the baffle with the shroud permits the neck portions of the baffle to be maintained in alignment with the exhaust slots in the shroud as the shroud is rotated by a user during operation of the sander. Thus, the baffle is free to rotate relative to the housing but not relative to the shroud itself. The baffle serves to more effectively direct a cooling airflow drawn in by a fan 40 through inlet slots 21 in a top member 14 associated with the housing 12 such that the airflow is more directly exhausted from the interior area of the shroud. The design of the baffle further does not complicate the assembly of the sander 10 or otherwise add significantly to the overall cost of the sander.

Description: This invention relates to power sanders, and more particularly to a random orbit sander having an air directing baffle disposed therein for helping to exhaust a cooling airflow flowing through an interior area of the sander, to thus help better cool a motor disposed therein. Random orbit sanders are used in a wide variety of applications such as woodworking and auto body repair work. Such sanders typically employ a housing, a motor disposed within the housing, a shaft operably coupled to the motor, a shroud coupled to the housing for supporting and communicating with a dust bag (attached thereto), and a fan operably coupled to the motor shaft for drawing a cooling airflow in through openings in the housing and exhausting the cooling air flow through openings in the shroud to help cool the motor. GB-A-2,191,429 relates to a random orbit sander having a double sided fan with a first set of fan blades on the underside of the fan generating a dust extraction air flow and a second set of fan blades on the upper side of the fan generating a motor cooling airflow. Both airflows circulate within the part of the housing of the sander surrounding the fan and exit the housing of the sander through an outlet in the housing of the sander. With random orbit sanders such as described above, however, the cooling airflow drawn in through the openings in the housing is not most efficiently exhausted out of the openings in the shroud due to a lack of some structure within the shroud for directing the air flow out of the shroud. Thus, the cooling airflow is typically allowed to circulate within the shroud somewhat before being exhausted through the shroud openings. Moreover, the lack of structure more closely defining an airflow path out of the openings in the shroud somewhat degrades the strength of the suction force generated by the fan, and therefore the airflow that is drawn in through the openings in the housing. The shroud is preferably rotatably coupled to the housing to enable the dust bag thereof to be rotated out of the way by the user to enable convenient use of the sander. EP-A-659 522, which is relevant as prior art under Articles 54(3) EPC, relates to a random orbit sander having a double sided fan for dust extraction and motor cooling and a rotatable shroud. The shroud comprises at least one outlet for the motor cooling airflow and an exhaust outlet for the dust extraction airflow. A dust bag connectable to the exhaust outlet can thus be rotated to a convenient position during use. However, EP-A-659,522 does not address the problem of efficiently and effectively exhausting the motor cooling airflow taking into account the movement of the air outlets for the motor cooling airflow. It is therefore a principal object of the present invention to provide a baffle for a random orbit sander which serves to more efficiently and effectively exhaust a cooling airflow drawn in through the openings in an upper area of a housing thereof out of a shroud of such a sander, to thereby more effectively help to cool a motor disposed within the sander. The present invention provides a random orbit sander comprising: a housing having a member with an airflow inlet; a rotatable shroud positioned at a lower end of the housing and having an airflow outlet; a motor disposed within the housing; and a fan coupled to the motor for drawing a cooling airflow in through the inlet, around the motor, and into an interior area of the shroud; characterized by: a baffle disposed within said shroud for directing said cooling airflow entering said shroud outwardly through said outlet in said shroud and including means for engaging said shroud such that rotational movement of said shroud causes a corresponding rotational movement of said baffle. Preferably, the baffle comprises a generally annular opening fitted over a housing boss and a top surface engaged with a lower face of the housing for facilitating rotation of the baffle relative to the housing. Preferably the baffle may further comprise at least one neck portion registering with the shroud outlet which neck portions include means for engaging the shroud and causing conjoint rotational movement of the shroud and baffle. The engaging means preferably comprises a recess formed in the neck portion for engaging an inwardly protruding shoulder portion of the shroud. The interengagement of the neck portion with the inwardly protruding shoulder portion of the shroud prevents rotational movement of the baffle relative to the shroud itself. In this manner the shroud may be rotated by the user of the sander as needed to enable convenient operation without disrupting the alignment of the baffle relative to the shroud. The baffle of the present invention provides a more clearly defined airflow exhaust path through which air drawn in through the inlet in the top member by the fan may be easily exhausted through the outlets in the shroud. The better defined airflow exhaust path enables the cooling air flow to more efficiently cool the motor. Without the baffle, air drawn into the shroud is free to circulate to some degree within the interior area defined by the shroud, thus somewhat impeding the exhaust of the airflow and thereby reducing the effectiveness of the cooling airflow in helping to cool the motor. The various advantages of the present invention will become apparent to one skilled in the art by reading the following specification and subjoined claims and by referencing the following drawings in which: Figure 1 is an elevational perspective view of a random orbit sander with which the baffle of the present invention is used; Figure 2 is a partial cross sectional side view of the sander of Figure 1 in accordance with section line 2-2 in Figure 1 showing a preferred embodiment of a baffle in accordance with the present invention; Figure 3 is a bottom view of the baffle of Figure 2; Figure 4 is an elevational side view of the baffle shown in Figure 2; and Figure 5 is a plan view of the baffle of Figures 2-4 in assembly relation with the shroud of the sander in accordance with section line 5-5 in Figure 2, understanding that the platen has not been illustrated in Figure 5. Referring to Figure 1, there is shown a random orbit sander 10 with which a preferred embodiment of the present invention may be used. The sander 10 generally includes a housing 12 having a two-piece clam shell construction, with the two-pieces thereof held together when assembled by a single-piece top member 14. The housing 12 further includes a lower portion 16 having a two-piece shroud 18 rotatable relative to the housing 12 and secured thereto. The sander 10 further includes a platen 20 driven in a random orbital fashion by a motor (not shown) disposed within the housing 12, and a fan (not shown) driven by the motor. The top member 14 of the housing 12 includes a series of inlets 21 through which a cooling ambient airflow may be drawn into an interior area of the housing 12, an on/off power button 22 and a neck portion 24 through which a power cord 26 coupled to the motor may extend to supply electrical current to the motor. The shroud 18 is removably coupled to a neck portion 28 of a dust bag 30. The shroud 18 further includes a plurality of diametrically opposed outlet (i.e., exhaust) slots 32 (only one being shown) through which the cooling ambient airflow drawn in through the inlets 21 into an interior area of the shroud 18 by the fan may be exhausted from the shroud 18. The sander 10 is operated by grasping the top member 14 with a hand, and typically with the palm of a hand, and turning on the motor via the on/off switch 22. The dust bag 30 may be rotated with the other hand into a position so that the sander 10 can be conveniently used on a work surface. Once turned on, the motor within the sander 10 drives the platen 20 in a random orbital fashion. Referring now to Figure 2, the motor can be seen and is denoted by reference numeral 34. An armature 36 of the motor is operably coupled to a shaft 38, which is in turn fixedly secured to the fan, denoted by reference numeral 40, in part by a threaded screw 42. The platen 20 is also operably secured to the shaft 38 via a plurality of threaded screws 44 (only one being shown) extending through a corresponding plurality of openings 45 in the platen 20 and an eccentrically disposed bearing 46. The bearing 46 causes a random orbital movement of the platen 20 in response to driving rotation of the shaft 38. A second bearing 48 helps maintain the shaft 38 in longitudinal alignment with the axial center of the housing 34 in spite of the forces created by driving the platen 20 eccentrically relative to the shaft 38. Rotation of the shroud 18 is enabled by engagement of a lip 18a of the shroud 18 within a channel 16a formed in the lower end portion 16 of the housing 12. With further reference to Figure 2, the fan 40 includes a downwardly projecting plurality of blades 50 and an upwardly projecting plurality of blades 52. The downwardly projecting plurality of blades 50 enable the fan 40 to create a suction force when the motor 34 is operated which causes air to be drawn in through openings 54 in the platen 20 and into the dust bag 30 (Figure 1). In this manner the fan 40 helps to pick up sanding dust off of the work surface. The upwardly projecting fan blades 52 of the fan 40 create a suction force to draw a cooling ambient airflow in through the inlets 21 in the top member 14, down around the motor 34, through the interior of the housing 12, into the interior area of the shroud 18, and outwardly through the outlet slots 32 in the shroud 18. In this manner, the upwardly projecting fan blades 52 operate to generate a cooling airflow when the motor 34 is turned on to help maintain the motor 34 relatively cool during operation of the sander 10. Referring now to Figures 2-4, an airflow means constituted by a baffle 56 in accordance with a preferred embodiment of the present invention will now be described. With initial reference to Figures 3 and 4, the baffle 56 includes a main body portion 58 which forms an annular opening 60. The main body portion 58 further includes a generally planar top surface 59, a downwardly depending wall portion 61 for at least partially enclosing the fan 40, and a pair of diametrically opposed neck portions 62. Each of the neck portions 62 has a width approximately equal to the width of each of the outlet slots 32 and further includes a recessed portion 64, the function of which will be described momentarily. With brief reference to Figures 2 and 5, the shroud 18 further includes a pair of inwardly projecting shoulder portions 66 which are diametrically opposed from one another, and approximately centered over each of the openings 32 in the shroud 18. The lower portion 16 of the housing 12 further includes a generally circular boss portion 68 and a generally planar lower face surface 70. The baffle 56 is coupled to the housing 12 during assembly by placing it over the generally circular boss portion 68 such that the boss portion 68 extends through the annular opening 60 (shown in Figure 3). When assembled, the top surface 59 is in abutting contact with the lower face surface 70. The baffle 56 is thus free to rotate about the boss portion 68 of the housing 12. With further reference to Figures 2-5, the recessed portions 64 in the neck portions 62 of the baffle 56 interengage with the inwardly protruding shoulder portions 66 of the shroud 18 to prevent rotational movement of the baffle 56 relative to the shroud 18, as shown particularly well in Figures 2 and 5. Accordingly, the baffle 56 is caused to rotate in accordance with rotational movement of the shroud 18 relative to the housing 12 but is not free to rotate relative to the shroud 18. In this manner the neck portions 62 are always maintained in alignment with the outlet slots 32 of the shroud 18. With further reference to Figures 2-4, the baffle 56 helps to provide a better-defined airflow exhaust path for ambient cooling airflow that is drawn in through the inlets 21 in the top member 14. The baffle 56 enables the cooling air flow to be effectively exhausted from the interior area of the shroud 18, to thus help to better cool the motor 34. Since ambient air drawn in through the inlets 21 is not free to circulate within the complete interior area of the shroud 18, the suction force generated by the fan 40 is increased, thus further helping to cool the motor 34. Additionally, since the baffle 56 is not free to rotate relative to the shroud 18, but is rather interengaged with the shroud 18 such that the neck portions 62 are always aligned with the outlet slots 32 in the shroud 18, the shroud 18 may be rotated by the user to a convenient position when using the sander 10 without affecting the alignment of the baffle 56 relative to the shroud 18. Thus, the baffle 56 does not adversely affect convenient operation of the sander 10 by the user. The baffle 56 may be constructed from a wide variety of methods, but is preferably injection molded from a suitably strong plastic. In this manner the baffle 56 is advantageously formed as a relatively inexpensive, single piece component. The uniquely simple but effective design of the baffle 56 further allows it to be assembled with the sander 10 during assembly of the sander 10 without significantly complicating the assembly process or otherwise adding appreciably to the overall cost of the sander 10. It will be appreciated, however, that the baffle of the present invention could alternatively be integrally formed within the interior of the shroud 18, if so desired. At present, however, it is expected that manufacturing of the baffle 56 as an independent component will be more cost effective than manufacturing it as an integral part of the shroud 18. Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular embodiments thereof, modifications and variations will become apparent to the skilled practitioner, the scope of protection being determined by the attached claims.

Claims: A random orbit sander (10) comprising: a housing (12) having a member (14) with an airflow inlet (21), a rotatable shroud(18) positioned at a lower end (16) of the housing (12) and having an airflow outlet (32), a motor (34) disposed within the housing, and a fan (40) coupled to the motor for drawing a cooling airflow in through the inlet, around the motor, and into an interior area of the shroud, characterized by: a baffle (56) disposed within said shroud for directing said cooling airflow entering said shroud outwardly through said outlet in said shroud and including means (64) for engaging said shroud such that rotational movement of said shroud causes a corresponding rotational movement of said baffle. A sander according to claim 1, characterised in that said baffle comprises at least one neck portion (62) extending to register with said outlet in said shroud. A sander according to claim 2, characterised in that said means for engaging said shroud comprises a recess (64) formed in said neck portion for engaging a shoulder portion (66) protruding inwardly from an interior of said shroud. A sander according to any one of the preceding claims, characterised in that the baffle comprises a sidewall portion (61) adapted to partially circumscribe said fan. A sander according to claim 1, characterised in that said baffle further comprises: a generally annular opening (60) fitted over a protruding boss portion (68) on the lower end of the housing; and a generally planar top surface (59) engaging a lower face surface (70) of the lower end portion of the housing. A sander according to any one of the preceding claims, characterised in that the baffle is integrally formed within the interior of the shroud. A sander according to claim 1 characterised in that the baffle (56) comprises: an annular main body portion (58); first and second neck portions (62) protruding outwardly of said main body portion approximately circumferentially opposite one another; each neck portion including a recess (64) for engaging with a protruding shoulder portion (66) on an inner wall of the shroud to thereby cause the baffle to engage the shroud such that the shroud and baffle are conjointly rotatable and the rotational movement of the baffle relative to the shroud is prevented; a generally flat top surface (59) engaging a lower face (70) of a lower end portion of the housing; and an annular opening (60) formed in the flat top surface and rotatably supported on a generally circular lower boss portion (68) of the housing. A sander according to claim 7 characterised in that the main body portion (58) includes a downwardly depending wall portion (61) for at least partially enclosing the fan and for helping direct the airflow generated by the fan out of the shroud through the exhaust outlets in the shrouds.

Inventors: HOWARD THOMAS J JR, SUTTON DAVID L, HOWARD, THOMAS J., JR., SUTTON, DAVID L.
Applicants: BLACK & DECKER INC, BLACK & DECKER INC.
Application year: 1995
Main classification: B25F5
IPC codes: B24B55, B25F5