SIGNAL SWITCHES FOR POWER TOOLS

Abstract

A signal switch (200) for a power tool, comprising: a lower housing assembly (230) having: a plurality of side walls connected to collectively define an interior space; a bottom wall (232) attached to a lower portion of the plurality of side walls and covering a lower portion of the interior space, the bottom wall (232) defining at least one opening (236); an actuator (240) pivotally supported within the interior space, the actuator (240) having a first end (246) and a second end (248); an upper housing assembly (228) having: a top wall attached to an upper portion of the plurality of side walls and covering the upper portion of the interior space, the top wall defining an opening; a paddle (226) extending through the opening and having an arm (256) located within the interior space;a tilting mechanism (252) configured to allow the paddle (226) to pivot between an ON position and an OFF position; and a spring-loaded pressing member (260) at one end of the arm (256); and a microswitch circuit board (242) comprising: a circuit board attached to the bottom wall (232), the circuit board defining at least two slots (244) through which the at least two fixed terminals (234) extend; at least one microswitch (238) on an inner side of the circuit board positioned to extend through the at least one opening (236) in the bottom wall (232) and into the interior space; an electrical connector (262) on an outer side of the circuit board, the electrical connector (262) configured to connect to an electrical cable (272);andconductive traces (264) electrically connected to the microswitches (238) and the electrical connector (262),wherein, when the paddle (226) is in the ON position, the arm (256) is positioned such that the pressing member (260) presses the second end (248) of the actuating member (240) into engagement with the at least one microswitch (238) projecting into the interior space, andwherein, when the paddle (226) is in the OFF position, the arm (256) is positioned such that the pressing member (260) presses the first end (246) of the actuating member (240) downward, thereby moving the second end (248) of the actuating member (240) away from the at least one microswitch (238);

Description

CROSS-REFERENCE TO RELATED APPLICATIONS TECHNICAL FIELD

[0001] This application relates generally to power tools and, in particular, to power switches for power tools. BACKGROUND

[0002] Some power tools and other types of devices have specific requirements for the power switch or on / off switch. For example, with power tools such as table saws, the user should not be able to accidentally turn the power tool on. The switch should be able to be turned off blindly, meaning the user does not need to see the switch to turn it off, and should be able to be turned off with the user's hand, knee, or other body part.

[0003] Generally, two types of switches are used for table saws and similar types of power tools. One type of switch is a toggle switch with a large paddle lever, as in the Fig. 5 and Fig. 6. Another type of switch is a push button switch with two buttons (ON / OFF) provided on a large pad, as shown in Fig. 7. A problem faced by power tool circuit breakers is the accumulation of oxidation on exposed conductors, which can shorten their service life. Power tool electrical switches that receive power from an AC outlet are less prone to oxidation due to the high AC voltage and high current flowing through the switch contacts, which prevents oxidation from accumulating. However, battery-operated power tools typically have very low DC voltage and current flowing through the contacts, which may not be enough to prevent oxidation from accumulating. Harsh environments, such as high temperature and humidity, can exacerbate this problem.

[0004] Contact oxidation and harsh environments have a greater impact on battery-powered tools. Battery-powered tools often use microswitches that can handle DC voltage and current and are IP-rated, protecting them from harsh environments. However, it is difficult to use microswitches in power tools, such as table saws, which are configured to be operated blindly by bumping the switch with a hand, knee, or other body part. For example, typical table saw switches can generate a high amount of kinetic energy, which is transferred to the contacts by the trigger when the switch is closed. Microswitches could easily be damaged if operated in this way.

[0005] Document WO 2015 / 036 911 A1 discloses a switch control device comprising: a key secured to a housing structure; at least one actuating element connected to the key at a first end and thus moving integrally therewith; a base adapted to fit into a lower part of the housing, to which an electrical circuit including at least one microswitch is mechanically secured.

[0006] The document US 2012 / 0 217 144 A1 discloses a switching device comprising a pivotable actuating body held in a housing, a driving body held in the housing and made pivotable by the actuating body, and a switching element pressed by the driving body.

[0007] Document EP 2 743 953 A1 discloses a switching device comprising: a knob rotatable about a first shaft; a cam rotatable about a second shaft and rotated from a reference position in a predetermined direction; a first switching element that is switched on when the cam is rotated in one direction about the second shaft; and a second switching element that is switched on when the cam is rotated in the other direction about the second shaft.

[0008] A switch configuration is required that allows the use of microswitches in power switches for power tools, such as table saws, while still permitting blind actuation by the hand, knee, or other body part, and that is not susceptible to oxidation and harsh environments. SUMMARY

[0009] The invention provides a signal switch for a power tool having the features of claim 1 and a power tool having the features of claim 3.

[0010] A signal switch for a power tool is provided, including a lower housing assembly having a plurality of side walls joined to collectively define an interior space, and a bottom wall attached to a lower portion of the plurality of side walls and covering a lower portion of the interior space, the bottom wall defining at least one opening. An actuator having a first end and a second end is pivotally supported within the interior space. The signal switch further includes an upper housing assembly having a top wall attached to an upper portion of the plurality of side walls and covering the top portion of the interior space. A paddle extends through an opening in the top wall. The paddle has an arm located within the interior space. A tilting mechanism is configured to allow the paddle to pivot between an ON position and an OFF position.A spring-loaded pressing member is provided at one end of the arm. The signal switch further includes a microswitch circuit board attached to the bottom wall. At least one microswitch is provided on an inner side of the circuit board in a position such that it extends through the at least one opening in the bottom wall and protrudes into the interior space. At least two microswitches may be used to meet safety requirements. An electrical connector is provided on an outer side of the circuit board and is configured for connection to an electrical cable. Conductive traces on the circuit board are electrically connected to the microswitches and the electrical connector. When the paddle is in the ON position, the arm is positioned such that the pressing member presses the second end of the actuating member into engagement with the at least one microswitch protruding into the interior space.When the paddle is in the OFF position, the arm is positioned so that the pressing member presses the first end of the actuator downward, thereby moving the second end of the actuator away from the at least one microswitch. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a table saw having a signal switch according to the present disclosure. Fig. 2 is an exploded view of certain components of the table saw of Fig. 1. Fig. 3 is a schematic diagram of the electrical system of the table saw of Fig. 1. Fig. 4 is a partial perspective view showing the power switch of the table saw of Fig. 1 shows. Fig. 5-7 show embodiments of power switches according to the prior art. Fig. 8 is a side view of a signal switch according to the present disclosure. Fig. 9 is a bottom perspective view of the signal switch of Fig. 8. Fig. 10 is a perspective view of the microswitch circuit board of the signal switch of Fig. 8. Fig. 11 is a schematic cross-sectional view of the signal switch of Fig. 8, which shows the switch in the OFF position. Fig. 12 is a schematic cross-sectional view of the signal switch of Fig. 8, which shows the switch in the ON position. Fig. 13 is a perspective view of the microswitch circuit board of a signal switch according to another embodiment. Fig. 14 is a schematic cross-sectional view of a signal switch of another embodiment having fixed terminals. DETAILED DESCRIPTION

[0011] For a better understanding of the principles of the device described herein, reference is now made to the embodiment(s) illustrated in the figures and described in the following written description. It is understood that this is not intended to limit the scope of the device. Furthermore, it is understood that the device includes any changes and modifications to the illustrated embodiment(s) and further includes other applications of the principles of the device that would normally be apparent to one of ordinary skill in the art to which this device relates.

[0012] The present disclosure is directed to a power switch for a power tool, such as a table saw, that allows microswitches to be used as an ON / OFF power switch for the power tool while still allowing easy / blind actuation with a user's hand, knee, or other body part, and that is not susceptible to oxidation and harsh environments. As discussed below, the power switch has a toggle switch configuration with microswitches extending into the switch for actuation by the toggle lever. The microswitches are provided on a circuit board mounted on the bottom side of the switch. The circuit board has conductive traces that connect the microswitches to a connector provided on the circuit board.The connector enables the use of a cable, such as a ribbon cable, to provide a signal from the switch to the signal panel and from the signal panel to the power tool's main board. The interior of the switch housing is sealed from the external environment, shielding the switch's mechanical components from the environment.

[0013] In the embodiment described here, the power tool comprises a table saw, although the power switch can be used with any type of power tool of the device. With reference to Fig. 1, the table saw assembly 100 includes a base 104 and a table top 102. As shown in the Fig. 1 and Fig. 2, a power tool in the form of a table saw 100 includes a blade assembly 101, a table structure 102, and a base 104. The table 102 includes an opening or slot 106 through which an upper portion of the blade assembly 101 extends. The table 102 has a generally planar upper surface, which may be referred to as a work surface. The frame 104 is connected to a lower portion of the table 102 and is configured to define an interior space 105 in which the lower portion of the blade assembly 101 is positioned. In the embodiment of Fig. 1, the table structure 102 and frame 104 may be formed from sheet metal, plastic, aluminum, composite materials, or the like. The table 102 and frame 104 may include handles, such as handle 108, that allow a user to conveniently carry the table saw 100.

[0014] In certain embodiments, the blade assembly 101 has a fixed position along the longitudinal axis L of the table 102 or along the length of the slot 106. In other embodiments, the blade assembly 101 may be mounted on a sliding assembly (not shown) that allows the blade assembly to move longitudinally relative to the table 102, commonly referred to as an underfloor saw.

[0015] The blade assembly 101 of the table saw 100 includes an adjustment mechanism 110 for adjusting the angular and vertical position of the blade. The mechanism 110 is configured to allow rotation of the blade assembly 101 about the longitudinal axis L so that the blade can make an angled cut in the workpiece. The mechanism may also be configured to raise and lower the saw blade relative to the table 102 to adjust the depth of the cut into the workpiece.

[0016] As in Fig. 2, the blade assembly 101 generally includes a blade 120, an electric motor assembly 122, and a carriage assembly 124 with a cover assembly 126. The carriage assembly 124 includes a pivot mount 125 pivotally mounted on the underside of the table 102 to permit pivoting of the blade assembly, and thus the blade 120, about the longitudinal axis L ( Fig. 1). The motor assembly 122 is supported in a channel 128 in the carriage assembly, which is configured to allow the motor assembly, and therefore the blade 120, to move up and down relative to the table 102 and the slot 106. The blade 120 may be configured for rotary and reciprocating motion depending on the nature of the table saw 100, and the motor assembly 122 is configured to drive the blade in rotary motion.

[0017] The adjustment mechanism 110 includes a mechanism for controlled pivoting of the carriage assembly 124 relative to the table 102 and for controlled up-and-down movement of the motor assembly 122 relative to the table, ultimately providing controlled positioning of the saw blade 120. It should be understood that a variety of adjustment mechanisms may be used to provide the angle and up-down adjustments for the blade 120. For example, a lead screw mechanism may be provided to move the motor assembly 122, and thus the blade 120, up and down relative to the carriage assembly 124 and thus relative to the table 102 and the work surface. The angle adjustment mechanism may include a shaft 112 that engages a curved slot 113 in a side wall 114 of the frame 104.Shaft 112 may form part of a gear mechanism for driving a height-adjustment lead screw. Other mechanisms are contemplated, as long as they are at least capable of adjusting the angle of blade 120 relative to table 102 and slot 106.

[0018] A signal switch 200 according to the present disclosure is provided on a front portion of the table saw 100 where it is easily accessible to a user during operation of the table saw. The power signal is preferably a low-voltage signal, although any voltage and / or current level may be used for the power signal. The power signal is used to signal the control system when the table saw should be activated and deactivated and is not used to supply power to the control system.

[0019] With reference to Fig. 4, the signal switch 200 includes a housing 220 that is attached to the power tool housing 222. The switch housing 220 is secured to the power tool housing by fasteners 224, such as screws. The switch 200 includes a paddle 226 that is used to open and close a circuit that supplies the power signal to the control system. The circuit can receive power from the interface circuit power distribution system or apply the signal to the control system.

[0020] An embodiment of an electrical system is shown in Fig. 3. The electrical system includes a control system 202, a safety system 204, and a power distribution system 206. The control system 202 includes the components used to control the table saw, such as a processor, memory, and the like. The control system 202 may be implemented on a printed circuit board (PCB). The safety system 204 includes electrical components and circuitry configured to detect operating conditions that could result in damage to the saw or injury to an operator of the tool, and to implement strategies to prevent such damage or injury, such as stopping the blade, interrupting the power supply, etc. The safety system 204 may be implemented on the same PCB or a separate PCB from that of the control system.The power distribution system 206 includes the components and circuitry that supply power to the drive system of the power tool.

[0021] The power is provided by a power supply 210. The power supply may be an AC outlet or a battery. In the embodiments described here, the power tool is a battery-operated table saw, whereby the Fig. 3 is a battery. The signal switch 200 is configured to manually open and close the signal circuit to indicate to the control system 202 when power should be applied or removed from the various systems of the power tool.

[0022] Fig. 8-12 show an embodiment of the signal switch 200 in more detail. The signal switch 200 includes an upper housing assembly 228 and a lower housing assembly 230. The lower housing assembly 230 includes a plurality of side walls surrounding and defining an interior space. The upper housing assembly 228 is mounted on top of the lower housing assembly 230 and closes the upper portion of the interior space. The lower housing assembly 230 includes a bottom wall 232 ( Fig. 11), which closes the lower part of the interior.

[0023] As in the Fig. 11 and Fig. 12, the bottom wall 232 defines openings through which the microswitches 238 for the signal switch 200 extend into the interior. The number of microswitch openings 236 depends on the number of microswitches 238 used. As shown, two microswitches 238 are used, thereby providing two openings in the bottom wall 232. An actuator 240 for actuating the microswitches 238 is provided in the interior of the lower housing assembly 230. The microswitch circuit board 242 is mounted on the bottom wall 232 on the lower housing assembly 230. The microswitch circuit board 242 may be implemented as a printed circuit board assembly (PCBA) and may be mounted to the lower housing assembly 230 in any suitable manner.

[0024] The microswitches 238 are provided on the upper side of the circuit board 242 in such positions that they extend through the corresponding openings 236 provided in the lower wall 232 of the lower housing assembly 230. In the embodiment of the Fig. 8-12, two microswitches 238 are used, although any suitable number of microswitches may be used. The microswitches 238 extend into the interior of the lower housing assembly 230 to a suitable extent to allow actuation by the actuator 240. In one embodiment, the microswitches 238 are configured to extend into the interior such that only the trigger buttons on top of the switches 238 protrude above the inner surface of the bottom wall 232, as shown in FIGS. Fig. 11 and Fig. 12 can be seen.

[0025] The actuating member 240 is pivotally supported in a position for actuating the microswitches 238, for example, by pressing the buttons on top of the microswitches 238. The actuating member 240 has a first end 246 and a second end 248. The actuating member 240 is pivotally supported by a pivot assembly 250 in a position on the bottom wall in which one end, for example, the second end 248, of the actuating member 240 can be pivoted into and out of engagement with the microswitches 238. In particular, the actuating member 240 is configured to pivot between a first position and a second position. In the first position, the second end 248 of the actuating member 240 is spaced from the microswitches 238 such that the microswitches 238 are not actuated, as shown in Fig. 11. This corresponds to the OFF position for the signal switch. To pivot the actuator to the second position, the second end of the actuator 240 is pivoted downward into contact with the microswitches 238, as shown in Fig. 12. This corresponds to the ON position for the signal switch.

[0026] The upper housing assembly 228 includes the paddle 226, a tilt mechanism 252, and a spring assembly 254. The paddle 226 is manually moved by the user to turn the table saw on and off. The paddle 226 includes a large actuating portion to facilitate user contact. The actuating portion may also include markings such as arrows, alphanumeric characters, and symbols to indicate the ON and OFF positions, directions of travel, or any other information to assist and guide a user.

[0027] The paddle 226 is pivotable by the tilting mechanism 252, which allows the paddle 226 to move between an OFF position ( Fig. 11) and an ON position ( Fig. 12) is attached to the upper housing assembly 228. The toggle mechanism 252 may be configured in the same manner as a toggle switch, as are known in the art. In the OFF position, the paddle 226 is directed downward and positioned close to the side of the power tool. The position and orientation of the paddle 226 in the OFF position is selected to prevent and / or reduce the likelihood of inadvertent contact of the paddle with the switch that moves the paddle to the ON position.

[0028] The paddle 226 is swung from the side of the power tool to turn on the power tool. With reference to Fig. 12, in the ON position, the paddle 226 extends outwardly from the power tool to a location that is easily accessible during operation. The paddle 226 can then be easily moved to the OFF position by touching the paddle with a hand, knee, or other body part without the paddle being visible. The paddle 226 has an arm portion 256 that extends into the interior. A spring arrangement is provided on the arm. For example, in one embodiment, the arm 256 comprises a hollow tube in which a pressing member 260, such as a ball or plunger, is retained. A spring (not shown) is provided in the arm 256 to bias the pressing member to an extended position in which the pressing member projects from the end of the arm so that it can resiliently engage the actuating member 240.

[0029] When the paddle 226 is in the Fig. 12, the pressing member 260 is moved into engagement with the second end 248 of the actuating member 240, causing the actuating member 240 to pivot into engagement with the microswitches 238, thereby actuating the microswitches. When the paddle 226 is moved to the Fig. 11, the pressing member 260 is moved into engagement with the first end 246 of the actuating member 240, causing the actuating member 240 to pivot into the non-actuating position in which the second end 248 of the actuating member 240 is spaced from the microswitches 238.

[0030] The microswitch circuit board 242 has an electrical connector 262 and conductive traces 264. The conductive traces 264 are electrically connected to the microswitches 238 and the electrical connector 262. The conductive traces 264 are used to conduct a signal from the microswitches 238 to the electrical connector 262. Although this is not shown in the Fig. 8-12, other electrical components may be provided on the microswitch circuit board 242 as necessary to enable the handling and routing of the signal through the microswitch circuit board 242.

[0031] The electrical connector 262 is configured for connection to a complementarily configured connector 270 on a cable 272, such as a ribbon cable or other suitable type of cable. As is known in the art, ribbon cables comprise a plurality of separate insulated conductors arranged in a flat, parallel manner. Connectors with a predetermined configuration are provided at each end of the cable. The ribbon cable extends from the microswitch circuit board and is connected by the other end of the cable to the signal board of the table saw's main circuit board. Thus, the cable forms part of the signal circuit for the table saw and allows the signal to be smoothly and easily routed from the switch to the power tool's systems.

[0032] The interior of the power switch is sealed from the external environment through the use of gaskets and sealing material at appropriate locations within the switch. For example, the signal switch 200 includes a gasket 266 at the point where the paddle extends through the upper housing assembly 228 into the interior. Furthermore, a sealant 268 is provided to seal the interface between the microswitch circuit board 242 and the lower housing assembly 230. Thus, the interior is sealed from the environment, protecting the mechanical components of the switch, such as the actuator 240 and the buttons of the microswitches 238, from dust and contamination.

[0033] With reference to the Fig. 13 and Fig. 14, a signal switch 200 can be implemented by adding the circuit board and microswitches to a toggle switch, whereby the toggle assembly of the switch can be used to actuate the microswitches. As shown in Fig. As can be seen in Figure 14, the power switch may have fixed terminals mounted on the lower surface of the bottom wall 232, which would have been used to connect the switch to a power circuit. The fixed terminals 234 may be used for the precise positioning of the microswitch circuit board. As best shown in Fig. 13, the microswitch circuit board 242 may include openings or slots 244 through which the fixed terminals 234 extend for precise positioning when the microswitch circuit board 242 is mounted to the lower housing assembly 230.

[0034] Although the disclosure has been fully illustrated and described in the drawings and the foregoing description, it should be considered as illustrative and not restrictive in nature. It is understood that only the preferred embodiments have been presented, and that all changes, modifications, and other applications that fall within the scope of the disclosure are intended to be protected.

Claims

[1] Signal switch (200) for a power tool, comprising: a lower housing assembly (230) comprising: several side walls connected to define an interior space; a lower wall (232) attached to a lower portion of the plurality of side walls and covering a lower portion of the interior space, the lower wall (232) defining at least one opening (236); an actuator (240) pivotally supported in the interior space, the actuator (240) having a first (246) and a second end (248); an upper housing assembly (228) comprising: a top wall attached to an upper portion of the plurality of side walls and covering the upper portion of the interior space, the top wall defining an opening; a paddle (226) extending through the opening and having an arm (256) located in the interior; a tilting mechanism (252) configured to allow the paddle (226) to be pivoted between an ON position and an OFF position; and a spring-loaded pressing member (260) at one end of the arm (256); and a microswitch circuit board (242) comprising: a circuit board attached to the bottom wall (232), the circuit board defining at least two slots (244) through which the at least two fixed terminals (234) extend; at least one microswitch (238) on an inner side of the circuit board, positioned to extend through the at least one opening (236) in the bottom wall (232) and into the interior; an electrical connector (262) on an outer side of the circuit board, the electrical connector (262) being configured to connect to an electrical cable (272); and Conductor tracks (264) electrically connected to the microswitches (238) and the electrical connector (262), wherein, when the paddle (226) is in the ON position, the arm (256) is positioned such that the pressing member (260) presses the second end (248) of the actuating member (240) into engagement with the at least one microswitch (238) projecting into the interior, and wherein, when the paddle (226) is in the OFF position, the arm (256) is positioned such that the pressing member (260) presses the first end (246) of the actuating member (240) downward, thereby moving the second end (248) of the actuating member (240) away from the at least one microswitch (238). [2] Signal switch (200) according to claim 1, wherein the interior is sealed from an external environment. [3] Power tool comprising: a tool member configured to perform work; a drive system configured to drive the tool member; a power source configured to provide power to the propulsion system; a power circuit that supplies power from the power source to the drive system; a signal switch (200) electrically connected to the power circuit, the signal switch (200) comprising: a lower housing assembly (230) comprising: several side walls connected to define an interior space; a lower wall (232) attached to a lower portion of the plurality of side walls and covering a lower portion of the interior space, the lower wall (232) defining at least one opening (236); an actuator (240) pivotally supported in the interior space, the actuator (240) having a first (246) and a second end (248); an upper housing assembly (228) comprising: a top wall attached to an upper portion of the plurality of side walls and covering an upper portion of the interior space, the top wall defining an opening; a paddle (226) extending through the opening and having an arm (256) located in the interior; a tilting mechanism (252) configured to allow the paddle (226) to be pivoted between an ON position and an OFF position; and a spring-loaded pressing member (260) at one end of the arm (256); and a microswitch circuit board (242) comprising: a circuit board attached to the bottom wall (232); at least one microswitch (238) on an inner side of the circuit board, positioned to extend through the at least one opening (236) in the bottom wall (232) and into the interior; an electrical connector (262) on an outer side of the circuit board, the electrical connector (262) being configured to connect to an electrical cable (272); and Conductor tracks (264) electrically connected to the microswitches (238) and the electrical connector (262), an electrical cable (272) having a first connection end connected to the electrical connector (262) and a second connection end connected to a signal board of a main board of the power tool, wherein, when the paddle (226) is in the ON position, the arm (256) is positioned such that the pressing member (260) presses the second end (248) of the actuating member (240) into engagement with the at least one microswitch (238) projecting into the interior, and wherein, when the paddle (226) is in the OFF position, the arm (256) is positioned such that the pressing member (260) presses the first end (246) of the actuating member (240) downward, thereby moving the second end (248) of the actuating member (240) away from the at least one microswitch (238). [4] Power tool according to claim 3, wherein the interior of the signal lock holder (200) is sealed against an external environment. [5] The power tool of claim 3, wherein the electrical cable (272) comprises a ribbon cable. [6] Power tool according to claim 3, wherein the power tool is a table saw (100).

Images