US20140154118A1

US20140154118A1 - Power Tool with Peristaltic Pump

Info

Publication number: US20140154118A1
Application number: US13/690,200
Authority: US
Inventors: Eric Hendrickson
Original assignee: Robert Bosch GmbH; Robert Bosch Tool Corp
Current assignee: Robert Bosch GmbH; Robert Bosch Tool Corp
Priority date: 2012-11-30
Filing date: 2012-11-30
Publication date: 2014-06-05

Abstract

The present invention in one embodiment is a power tool including a housing, a main power shaft located within the housing, a peristaltic pump assembly positioned within the housing and operably connected to the main power shaft, and an outlet conduit operably connected to the peristaltic pump assembly and extending between the peristaltic pump assembly and an outlet port in the housing such that fluid is forced by the peristaltic pump assembly through the outlet conduit to a location outside of the housing.

Description

FIELD OF THE INVENTION

The present invention relates to power tools and more particularly to power tools which generate dust or debris during normal operation of the power tool.

BACKGROUND

Power tools are commonly used in various applications which generate significant amounts of dust or debris. By way of example, power tools are used to shape work pieces such as wood, drywall, etc. In many cases, a user marks the work piece so as to guide shaping of the work pieces. Thus, a line may be used to indicate where the work piece is to be cut. In some instances, the mark is only used to initially align the work piece with the power tool. Thereafter, the power tool is operated in a constrained manner such that the desired cut is almost automatically made. For example, a mark may initially be aligned with a blade on a table saw and thereafter a guide is used to precisely maneuver the work piece into contact with the blade.
In the forgoing example, once the work piece makes contact with the blade, the guide mark may be obscured by saw dust generated by the blade. In such cases, obscuration of the guide mark by saw dust may not be overly problematic. Nonetheless, many users still desire to see the guide mark as the cut is being made, if only to give a sense of security that the work piece has not become misaligned.
In other instances, a user actively modifies the alignment during a shaping operation. By way of example, jig saws and saber saws are commonly used to make curved cuts in a work piece. Accordingly, the user is constantly modifying the alignment of the power tool with respect to the work piece to follow the curved guide mark. In this type of scenario, obscuration of a guide mark by saw dust may result in a poor cut thereby requiring additional shaping operations or even ruining the work piece.
In some systems, removal of saw dust from an area that is being shaped is accomplished either by reliance upon air movement resulting from movement of the shaping component, such as a saw blade, or by a motor fan that is attached directly to the main power shaft of the tool and configured such that some of the air from the motor fan is directed toward a work piece. Such approaches may be unsatisfactory for a number of reasons. In some instances, the shaping component simply does not generate sufficient airflow to clear the saw dust. In tools including a motor fan, the motor fan is primarily configured to cool the motor. Accordingly, configuring the motor fan to further clear saw dust and debris severely limits the design of the tool.
Various alternatives are available to remove debris formed by the shaping operation in addition to those discussed above. Some power tools employ vacuum systems connected to the tool to remove cutting debris. The use of a vacuum system, however, often makes control of the tool more cumbersome, and the vacuum system itself can greatly increase the cost and complexity of a power tool. In other systems, a bellows is used to generate bursts of air which can be directed at the work piece. While such systems can be effective, the pulsed air flow can be distracting. Additionally, the reciprocating nature of the bellows activation mechanism may introduce undesired vibrations into the power tool.
Accordingly, there is a need for a power tool that allows increased visibility at the point of a shaping operation. A power tool that allows increased visibility at the point of a shaping operation without a reciprocating activation mechanism would be further beneficial.

SUMMARY

The present invention in one embodiment is a power tool including a housing, a main power shaft located within the housing, a peristaltic pump assembly positioned within the housing and operably connected to the main power shaft, and an outlet conduit operably connected to the peristaltic pump assembly and extending between the peristaltic pump assembly and an outlet port in the housing such that fluid is forced by the peristaltic pump assembly through the outlet conduit to a location outside of the housing.
In a further embodiment, a power tool includes a housing, a main power shaft at least partially located within the housing, a peristaltic pump assembly operably connected to the main power shaft, and an outlet conduit operably connected to the peristaltic pump assembly and extending between the peristaltic pump assembly and an outlet portion of the outlet conduit, the outlet portion configured to direct fluid toward a predetermined location.
These and other advantages and features of the present invention may be discerned from reviewing the accompanying drawings and the detailed description of a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may take form in various system and method components and arrangement of system and method components. The drawings are only for purposes of illustrating exemplary embodiments and are not to be construed as limiting the invention.

FIG. 1 depicts a simplified side cross-sectional view of a hand power tool incorporating features of the present invention with a peristaltic pump assembly operably connected to an end portion of a main power shaft opposite to the end portion of the main power shaft which is used to drive a shaping component;

FIG. 2 depicts a top cross-sectional view of the peristaltic pump assembly of FIG. 1;

FIG. 3 depicts a simplified side cross-sectional view of a hand power tool incorporating features of the present invention with a peristaltic pump assembly operably connected to the same end portion of a main power shaft which is used to drive a shaping component;

FIG. 4 depicts a side cross-sectional view of a diaphragm check valve in a closed position;

FIG. 5 depicts a side cross-sectional view of the diaphragm check valve of FIG. 4 in an open position;

FIG. 6 depicts a top cross-sectional view of a peristaltic pump assembly incorporating four of the check valves of FIG. 4 arranged to force fluid out of an outlet conduit regardless of the direction of rotation of the peristaltic pump assembly with the check valves in the positions resulting from a clockwise rotation of the pump shaft; and

FIG. 7 depicts a top cross-sectional view of the peristaltic pump assembly of FIG. 6 with the check valves in the positions resulting from a counter-clockwise rotation of the pump shaft.

DESCRIPTION

A hand power tool generally designated 100 is shown in FIG. 1. In the embodiment of FIG. 1, the power tool 100 includes a main housing portion 102. The main housing portion 102 houses a motor 104 and control electronics 106 for control of the power tool 100. The main housing portion 102 in one embodiment includes a battery receptacle for receiving a rechargeable battery pack (not shown). In one embodiment, the rechargeable battery pack (not shown) comprises a lithium-ion battery. The power tool 100 in other embodiments is powered by an external power source such as an external battery or a power cord.
The motor 104 is configured to selectively cause a main power shaft 108 to rotate. The main power shaft 108 in the embodiment of FIG. 1 is located completely within the housing 102. In other embodiments, a portion of the main power shaft 108 extends outwardly of the housing. A motor fan 110 is fixedly attached to the main power shaft 108 and configured to force cooling air against the motor 104 during operation of the power tool 100.
A shaping component 112, which in this embodiment is a circular blade, is operably connected to the main power shaft 108 by a shaping component gear 114 which is enmeshed with an end portion 116 of the main power shaft 108. The shaping component gear 114 is fixedly attached to a shaping component drive shaft 118 to which the shaping component 112 is removably attached by a bolt 120 and clamping assembly 122. In the embodiment of FIG. 1, the power tool 100 is configured for operably driving the shaping component 112 such that the shaping component 112 rotates about the shaping component drive shaft 118. In other embodiments, the power tool is configured to oscillate the shaping component which may be formed as a straight saw blade, for example.
The housing portion 102 includes an outlet port 124 located proximate to the location at which the shaping component drive shaft 118 extends outwardly of the housing 102. An end portion 126 of an outlet conduit 128 extends through the outlet port 124 and is directed generally along the shaping component 112. End portion 126 in some embodiments is a directional component that stops close to the housing or a flexible hose or tubing piece. The outlet conduit 128 extends along and within the housing 102 to a peristaltic pump assembly 140. The outlet conduit 128 is in fluid communication with the peristaltic pump assembly 140 which is described with additional reference to FIG. 2.
The peristaltic pump assembly 140 includes a pump gear 142 which is enmeshed with an end portion 144 of the main power shaft 108. The pump gear 142 is fixedly attached to a pump shaft 146 which is fixedly attached to a rotor 148. Two rollers 150/152 are rotatably supported by the rotor 148 through axles 154/156, respectively. The rollers 150/152 are configured to extend outwardly from the rotor 148 so as to contact an elastomeric tube 160. The elastomeric tube 160 includes an inlet portion 162 and an outlet portion 164. The elastomeric tube 160 extends about an arcuate pump casing 166 which in this embodiment is formed on the inner surface of the housing 102.
In operation, a user activates the power tool 100 such as by use of a power switch (not shown) and the control electronics 106 causes power to be applied to the motor 104. The motor 104 then causes the main power shaft 108 to rotate. In the embodiment of FIG. 1, the left side of the main power shaft 108, as depicted in FIG. 1, rotates out of the page while the right side of the power shaft 108 rotates into the page.
Rotation of the main power shaft 108 causes the shaping component gear 114 to rotate in an opposite direction. Thus, the right side of the shaping component gear 114, as depicted in FIG. 1, rotates out of the page while the left side of the shaping component gear 114 rotates into the page. Since the shaping component drive shaft 118 is fixedly attached to the shaping component gear 114, the shaping component drive shaft 118 rotates in the same manner as the shaping component gear 114. Similarly, since the shaping component 112 is attached to the shaping component drive shaft 118, the shaping component 112 also rotates in the same manner as the shaping component gear 114.
Rotation of the main power shaft 108 further causes the pump gear 142 to rotate in an opposite direction. Thus, the right side of the pump gear 142, as depicted in FIG. 1, rotates out of the page while the left side of the pump gear 142 rotates into the page. Since the pump shaft 146 is fixedly attached to the pump gear 142, the pump shaft 146 rotates in the same manner as the pump gear 114. Similarly, since the rotor 148 is fixedly attached to the pump shaft 146, the rotor 148 also rotates in the same manner as the pump gear 142. This results in a clockwise rotation of the rotor 148 as viewed in FIG.2, as indicated by the arrow 180.
As the rotor 148 rotates in the direction indicated by the arrow 180, the rollers 150 and 152 are forced in the direction of the arrows 182 and 184, respectively. The rollers 150 and 152 extend outwardly of the rotor 148 and are in contact with the elastomeric tube 160. Accordingly, as the rollers 150/152 are forced in the direction of the arrows 182 and 184, the rollers “roll” along the stationary elastomeric tube 160 and squeeze the elastomeric tube 160 against the arcuate pump casing 166. In the embodiment of FIG. 1, the rollers 150/152, rotor 148, elastomeric tube 160 and arcuate pump casing 166 are sized such that the elastomeric tube 160 is totally occluded at locations directly between the rollers 150/152 and the arcuate pump casing 166 (see FIG. 1). In other embodiments, the components are sized to provide only partial occlusion.
As the roller 150 moves toward the tube outlet 164 from the location depicted in FIG. 2, fluid within the elastomeric tube 160 between the roller 150 and the tube outlet 164 is forced through the elastomeric tube 160 and out of the tube outlet 164 as indicated by the arrow 186. The fluid is then forced into the outlet conduit 128 which is in fluid communication with the tube outlet 164. In one embodiment, the outlet conduit 128 is integrally formed with the elastomeric tube 160.
The fluid that is forced into the outlet conduit 128 flows out of the end portion 126 as indicated by the arrow 188 of FIG. 1. In the embodiment of FIG.1, the end portion 126 is located adjacent to the shaping component 112. In some embodiments wherein the fluid that is pumped is air, the end portion 126 is oriented such that the air flow will impact the area of a work piece that is being shaped by the shaping component 112, taking into account the effect of the movement of the shaping component 112. In embodiments wherein the fluid that is pumped is a liquid, the end portion 126 may be oriented such that the liquid contacts the shaping component 112, thereby cooling the shaping component 112.
Returning to FIG. 2, as the roller 150 forces fluid out of the tube outlet 164, the roller 152 forces fluid within the elastomeric tube 160 between the roller 150 and the roller 152 in the direction of the arrow 190. Accordingly, when the roller 150 moves past the tube outlet 164, the fluid between the roller 150 and the roller 152 is forced out of the tube outlet 164. Because the rollers 150/152 are located generally opposite to one another on the rotor 148, a substantially continuous stream of fluid is forced out of the tube outlet 164. In embodiments where a substantially continuous stream of fluid is not desired, a single roller may be used. In single roller embodiments, the distance between the inlet and the outlet portions of the tube along the arcuate pump casing may be modified to provide the desired interruption in the effluent stream. In embodiments with more than two rollers, the rollers are preferably equally spaced about the rotor.
Continuing with FIG. 2, the elastomeric tube 160 is made of a material which regains its shape once the pressure applied by the rollers 150/152 is removed at a particular location. Some commonly used elastomers include silicone, PVC, EPDM+polypropylene (as in SANTOPRENE), polyurethane and NEOPRENE. Extruded fluoropolymer tubes such as FKM (Viton, Fluorel, etc.) may also be used. Accordingly, as the roller 152 moves away from the tube inlet 162, the elastomeric tube 160 regains its shape, thus creating a vacuum which allows additional fluid to be forced into the elastomeric tube 160 through the tube inlet 162 behind the roller 152 as indicated by the arrow 192.
The elastomeric tube 160 is thus refilled with fluid until the roller 152 collapses the elastomeric tube 160 at a location adjacent to the tube inlet 162. In some embodiments, a filter (not shown) is used to filter fluid which comes through the tube inlet 162. The tube inlet 162 may be configured to take a suction within the housing 102 or from outside of the housing 102. By positioning the tube inlet 162 next to the motor 104, the effectiveness of the motor fan 110 may be increased. In embodiments wherein the fluid is a liquid, the tube inlet 162 may be immersed within a liquid reservoir.
While the invention is shown in one configuration in the embodiment of FIG. 1, the invention may be modified in a number of ways to support different designs. By way of example, FIG. 3 depicts a tool 200 which includes a main housing portion 202. The main housing portion 202 houses a motor 204 and control electronics 206 for control of the power tool 200. The motor 204 is configured to selectively cause a main power shaft 208 to rotate. A shaping component 212 is operably connected to the main power shaft 208 by a shaping component gear 214 which is enmeshed with an end portion 216 of the main power shaft 208.
The housing portion 202 includes an outlet port 224 located proximate to the location at which a shaping component drive shaft 218 extends outwardly of the housing 202. An end portion 226 of an outlet conduit 228 extends through the outlet port 224 and is directed generally along the shaping component 212. The outlet conduit 228 extends within the housing 202 to a peristaltic pump assembly 240.
The outlet conduit 228 is in fluid communication with the peristaltic pump assembly 240 which is substantially the same as the peristaltic pump assembly 140 of FIG. 2. The main difference is that the pump gear 242 is enmeshed with the end portion 216 of the main power shaft 208 at a location substantially opposite to the side of the main power shaft 208 whereat the shaping component gear 214 is enmeshed with the main power shaft 208.
In addition to modification of the physical location of the peristaltic pump assembly within or outside of the housing of a power tool, the function of the peristaltic pump assembly may be modified. As discussed above, in some embodiments the tube inlet to the peristaltic pump assembly is positioned to increase the effectiveness of a motor fan. In other embodiments, the tube outlet or outlet conduit is positioned to provide cooling directly to the motor of the power tool. In these embodiments, the tube inlet is typically not positioned to also take suction from the motor location.
While the embodiments of FIGS. 1 and 3 are power tools which rotatably drive a shaping component in only a single direction, in some embodiments, the main power shaft rotatably drives a shaping component in alternate directions. In embodiments wherein the main power shaft can be rotated in different directions, the peristaltic pump assembly is generally configured to produce the same flow of air through an outlet conduit. One such embodiment incorporates diaphragm check valves such as the check valve 250 depicted in FIGS. 4 and 5.
With initial reference to FIG. 4, the check valve 250 includes a seat portion 252 which is sealingly engaged with the inner wall 254 of a tube 256. A resilient diaphragm 258 is positioned in the seat 252 and configured such that in the absence of any pressure from fluid within the tube 256 acting upon the diaphragm 258, the diaphragm 258 is seated firmly against the seat 252. Accordingly, if pressure is applied to the diaphragm 258 in the direction of the arrow 260, the diaphragm 258 is more firmly seated against the seat 252 and no fluid is allowed to pass.
When pressure is applied in the direction of the arrow 262 of FIG. 5, however, the pressure resiliently deforms the diaphragm 258 forcing the diaphragm 258 away from the seat 252 as depicted in FIG. 5. Accordingly, the fluid providing the pressure is free to move past the seat 252 as indicated by the arrows 264/266.
With reference now to FIG. 6, a peristaltic pump assembly 280 includes a pump shaft 282 which is fixedly attached to a rotor 284. Two rollers 286/288 are rotatably supported by the rotor 284 through axles 290/292, respectively. An elastomeric tube 294 includes a first end portion 296 and a second end portion 298. The elastomeric tube 294 extends about an arcuate pump casing 300.
An inlet 302 is in interruptible fluid communication with the first end portion 296 through a check valve 304. The inlet 302 is also in interruptible fluid communication with the second end portion 298 through a check valve 306. An outlet conduit 310 is in interruptible fluid communication with the first end portion 296 through a check valve 312. The outlet conduit 310 is also in interruptible fluid communication with the second end portion 298 through a check valve 314.
The peristaltic pump assembly 280 is configured to provide fluid flow outwardly through the outlet conduit 310 regardless of the direction in which a main power shaft (not shown) operably connected to the pump shaft 282 is turning. By way of example, if the main power shaft (not shown) is rotated such that the pump shaft 282 turns in the direction of the arrow 316 of FIG. 6, the roller 288 will force fluid out of the second end portion 298. The check valve 306 is arranged such that an increase in pressure at the second end portion 298 causes the check valve 306 to be fully shut. Accordingly, no fluid passes through the check valve 306. The check valve 314, however, is arranged such that an increase in pressure at the second end portion 298 causes the check valve 314 to open. Accordingly, fluid passes through the check valve 314, resulting in a higher pressure at the outlet conduit 310.
At the same time that the roller 288 is forcing fluid out of the second end portion 298, the elastomeric tube 294 is regaining its normal shape as the roller 286 moves away from the first end portion 296, thereby creating a low pressure area at the first end portion 296. The resultant pressure drop from the higher pressure generated in the outlet conduit 310 as described above, along with the low pressure at the first end portion 296 causes the check valve 312 to be firmly seated. Additionally, the low pressure at the first end portion 296 causes fluid from the inlet 302 to move through the check valve 304 to the first end portion 296.
Consequently, rotation of the pump shaft 282 in the direction of the arrow 316 causes suction at the inlet 302 through the check valve 304 while fluid is emitted through the outlet conduit 310 by way of the check valve 314.
If the rotation of the pump shaft is reversed, the pump shaft 282 turns in the direction of the arrow 318 of FIG. 7, and the roller 286 will force fluid out of the first end portion 296. The check valve 304 is arranged such that an increase in pressure at the first end portion 296 causes the check valve 304 to be fully shut. Accordingly, no fluid passes through the check valve 304. The check valve 312, however, is arranged such that an increase in pressure at the first end portion 296 causes the check valve 312 to open. Accordingly, fluid passes through the check valve 312, resulting in a higher pressure at the outlet conduit 310.
At the same time that the roller 286 is forcing fluid out of the first end portion 296, the elastomeric tube 294 is regaining its normal shape as the roller 288 moves away from the second end portion 298, thereby creating a low pressure area at the second end portion 298. The resultant pressure drop from the higher pressure generated in the outlet conduit 310 as described above, along with the low pressure at the second end portion 298 causes the check valve 314 to be firmly seated. Additionally, the low pressure at the second end portion 298 causes fluid from the inlet 302 to move through the check valve 306 to the second end portion 298.
Consequently, rotation of the pump shaft 282 in the direction of the arrow 318 causes suction at the inlet 302 through the check valve 306 while fluid is emitted through the outlet conduit 310 by way of the check valve 312.
Therefore, by the addition of check valves, a peristaltic pump assembly can be configured to provide a stream of effluent through an outlet conduit regardless of the direction of rotation of a pump shaft. Thus, the peristaltic pump assembly may be used with power tools which allow for the direction of shaft rotation to be reversed.
While the present invention has been illustrated by the description of exemplary processes and system components, and while the various processes and components have been described in considerable detail, applicant does not intend to restrict or in any limit the scope of the appended claims to such detail. Additional advantages and modifications will also readily appear to those skilled in the art. The invention in its broadest aspects is therefore not limited to the specific details, implementations, or illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant's general inventive concept.

Claims

1. A power tool comprising:

a housing;

a main power shaft located within the housing;

a peristaltic pump assembly positioned within the housing and operably connected to the main power shaft; and

an outlet conduit operably connected to the peristaltic pump assembly and extending between the peristaltic pump assembly and an outlet port in the housing such that fluid is forced by the peristaltic pump assembly through the outlet conduit to a location outside of the housing.

2. The power tool of claim 1, wherein the peristaltic pump assembly comprises:

an arcuate pump casing;

a tube positioned along the arcuate pump casing;

a rotor and an eccentric shaft operably connected to the main power shaft; and

at least one roller rotatably supported by the rotor.

3. The power tool of claim 2, wherein the peristaltic pump assembly further comprises:

a pump shaft fixedly connected to the rotor; and

a pump gear meshed with the main power shaft.

4. The power tool of claim 3, wherein the at least one roller comprises:

a first roller extending outwardly from the rotor; and

a second roller extending outwardly from the rotor, the second roller extending outwardly from the first roller at a location generally opposite from the location at which the first roller extends outwardly from the rotor.

5. The power tool of claim 3, wherein:

the pump gear is meshed with a first end portion of the main power shaft; and

a second end portion of the main power shaft is configured for operably driving a shaping component.

6. The power tool of claim 5, wherein the power tool is configured to rotatably drive a shaping component.

7. The power tool of claim 3, wherein the outlet conduit extends outwardly of the outlet port.

8. The power tool of claim 7, wherein the outlet conduit and the elastomeric tube are integrally formed.

9. The power tool of claim 2, wherein the arcuate pump casing comprises a portion of the housing.

10. The power tool of claim 2, further comprising;

a check valve positioned between the outlet conduit and a first end portion of the elastomeric tube.

11. A power tool comprising:

a housing;

a main power shaft at least partially located within the housing;

a peristaltic pump assembly operably connected to the main power shaft; and

an outlet conduit operably connected to the peristaltic pump assembly and extending between the peristaltic pump assembly and an outlet portion of the outlet conduit, the outlet portion configured to direct fluid toward a predetermined location.

12. The power tool of claim 11, wherein the peristaltic pump assembly comprises:

an arcuate pump casing;

an elastomeric tube positioned along the arcuate pump casing;

a rotor operably connected to the main power shaft; and

at least one roller rotatably supported by the rotor.

13. The power tool of claim 12, wherein the peristaltic pump assembly further comprises:

a pump shaft fixedly connected to the rotor; and

a pump gear meshed with the main power shaft.

14. The power tool of claim 12, wherein the at least one roller comprises:

a first roller extending outwardly from the rotor; and

15. The power tool of claim 12, wherein:

the pump gear is meshed with a first end portion of the main power shaft; and

16. The power tool of claim 15, wherein the power tool is configured to rotatably drive the shaping component.

17. The power tool of claim 12, wherein:

the arcuate pump casing comprises a portion of a housing; and

at least a portion of the main power shaft is located within the housing.

18. The power tool of claim 12, wherein the outlet conduit and the elastomeric tube are integrally formed.

19. The power tool of claim 12, further comprising;

a first check valve positioned between the outlet conduit and a first end portion of the elastomeric tube; and

a second check valve positioned between the outlet conduit and a second end portion of the elastomeric tube.