Abstract:
A power tool has a housing and the housing includes a handle portion on which a starting switch for controlling the turning-on and turning-off of the power tool is mounted. A locking switch device adapted to selectively inhibit movement of the starting switch is mounted in the housing and includes first and second buttons respectively extending out from the two sides of the handle portion and positioned adjacent to the starting switch. A locking mechanism is arranged between the starting switch and the locking switch device and includes a linkage mechanism that is arranged between the first and second buttons. In this manner, upon one of the first and second button being pressed down, the linkage mechanism functions to cause the other one of the first and second buttons to be automatically moved to a position that corresponds to a pressed down state. The power tool with such a locking switch device is suitable for left-handed and right-handed operators and eliminates any uncomfortable feelings of handling the handle.

Description:
RELATED APPLICATION INFORMATION 
       [0001]    This application claims the benefit of CN 200920233046.2, filed on Jul. 13, 2009, the disclosure of which is incorporated herein by reference in its entirety. 
       BACKGROUND 
       [0002]    The subject disclosure generally relates to power tools and, more particularly, relates to a locking switch device for a power tool. 
         [0003]    There are a variety of power tools, which generally comprise a housing, a motor located in the housing, a power supply for supplying electricity to the motor and a cutting tool driven by the motor. The housing includes a handle portion. The power supply can be a DC power supply or an AC power supply. A starting switch for controlling the motor is mounted to the handle portion and, thereby, the user can contact the starting switch by his finger and operate the power tool conveniently when handling the handle portion. For safety, the power tool generally further comprises a locking switch device which can be designed to only have a lock-on function or a lock-off function or be designed to have the two functions simultaneously. The locking switch device having the two functions simultaneously is generally referred to as self-locking or anti self-locking switch device. The locking switch device with lock-on function can lock the starting switch in the switch-on position, that is to say, once the user presses down the starting switch and then presses down the button for locking the switch device, the starting switch can be kept in the switch-on position. The locking switch device with lock-off function can lock the starting switch in the switch-off position, that is to say, the starting switch can be pressed down only when the button for locking the switch device is pressed down, thereby effectively avoiding undesired operations resulting from the starting switch being pressed down accidentally by the user. 
         [0004]    In order to be adapted to left-handed operators and right-handed operators, the locking switch devices of some power tools comprise two buttons which are respectively arranged on the two sides of the handle portion and located as close as possible to the starting switch. In this manner, when any user handles the handle portion his thumb will be located adjacent to one of the two buttons while his other fingers will be located adjacent to the starting switch thus allowing any user to operate the locking switch device and starting switch and control the power tool simultaneously by one hand. 
         [0005]    In the above existing power tools, the locking switch device is designed to be located as closely as possible to the starting switch. This arrangement, however, also has a deficiency, that is, when the user presses down one locking switch button and the starting switch to operate the power tool, the other locking switch button is under the state of being not pressed down, and projects from the housing and usually leans against the palm of the user, which causes an uncomfortable feeling of handling. This may cause fatigue and abrade the hand of a user. 
       SUMMARY 
       [0006]    The subject disclosure is directed to an improved power tool having a locking switch device that is convenient for operation, conforms to the principle of human engineering, and improves the comfort of handling. To this end, the subject disclosure describes a power tool having a housing and a power supply. The housing has a handle portion on which is arranged a starting switch for controlling the turning-on and turning-off of the power tool. A locking switch device is arranged in the housing and a locking mechanism is arranged between the starting switch and the locking switch device. The locking switch device comprises a first button and a second button respectively extending out from the two sides of the handle portion and positioned adjacent to the starting switch. A linkage mechanism is arranged between the first button and the second button so that, once one of the first button and the second button is in the state of being pressed down, the other one of the first button and the second button is pressed down automatically. 
         [0007]    With the linkage mechanism between the first button and the second button, once one button is pressed down, the other one moves automatically towards the housing and then reaches the state of being pressed down. Thus, when the user handles the device, his palm can snugly contact the surface of the handle portion without having the uncomfortable feeling of an extended switch and the user can operate the power tool more easily. The arrangement disclosed hereinafter thus inherits the advantages in the prior art, i.e., the positional designs of the locking switch device and the starting switch which is convenient for the user to operate by one hand, while eliminating the disadvantage in the prior art, i.e., the uncomfortable feeling of dual switch handling. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The present invention will be further described with reference to the accompanying drawings, in which: 
           [0009]      FIG. 1  is an illustrative view of a power tool in the exemplary form of a reciprocating saw constructed according to the description that follows; 
           [0010]      FIG. 2  is a top view of the reciprocating saw of  FIG. 1 ; 
           [0011]      FIG. 3  is an explosive view of the locking switch device of  FIG. 1 ; 
           [0012]      FIG. 4  is an assembly view of the locking switch device and the starting switch of  FIG. 3 , wherein the shaft sleeve is removed; 
           [0013]      FIG. 5  is an illustrative view of the first button component of the locking switch device of  FIG. 3 ; 
           [0014]      FIG. 6  is an illustrative view of the second button component of the locking switch device of  FIG. 3 ; 
           [0015]      FIG. 7  is an illustrative view of the starting switch of  FIG. 3 ; 
           [0016]      FIG. 8  is a view illustrating the assembled state of the locking switch device of  FIG. 3  and the housing; 
           [0017]      FIG. 9  is an illustrative view of a further exemplary locking switch device constructed according to the description that follows; and 
           [0018]      FIG. 10  is a view illustrating the assembled state of the locking switch device of  FIG. 9  and the housing. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Referring to  FIG. 1 , the following describes a power tool in the exemplary form of a reciprocating saw having a locking switch device. It will be understood, however, that the described locking switch device can be used with other power tools, such as angle grinders, sanders, drills, etc. without limitation. 
         [0020]    As shown in  FIG. 1 , the reciprocating saw  10  comprises a housing  1 , a supporting frame  3 , and a power supply portion  5  carrying a power supply. A motor (not shown) is arranged in the housing  1 , and the supporting frame  3  and the power supply portion  5  are respectively arranged on the front end  11  and the rear end  12  of the housing  1 . In the present embodiment, the power supply carried by the power supply portion  5  is a battery pack, and in other embodiments, the power supply portion  5  may comprise an electrical connecting mechanism for receiving AC power supply or DC power supply. In operation, the supporting frame  3  contacts the material to be cut. The battery pack portion  5  is used for supplying electricity to the motor. A saw blade clamping device  7  is arranged on the front end  11  of the housing  1  for clamping a saw blade (not shown). The saw blade extends towards the exterior of the housing  1  through the supporting frame  3  and is driven by the motor to perform a linear reciprocating movement so as to saw or cut the material. 
         [0021]    The housing  1  is formed with a handle portion  13  at a position closer to the rear end  12  of the housing  1 . The radial dimension of the handle portion  13  is relative small to allow the handle portion  13  to be handled by a user. The handle portion  13  is provided with a starting switch  2  at a lower end thereof for controlling the turning-on and turning-off of the motor and the whole reciprocating saw. A locking switch device  4  is mounted in the handle portion  13 , and a locking mechanism is arranged between the locking switch device  4  and the starting switch  2 . In the present embodiment it is only after the locking switch device  4  is operated that the starting switch  2  can be pressed down to start the motor. Thus, the locking switch device  4  is a lock-off locking switch device. In other embodiments, the locking switch device can be designed as a lock-on locking switch device, or a locking switch device having lock-on and lock-off functions simultaneously. 
         [0022]    As shown in  FIG. 3 , the starting switch  2  is a trigger comprising a rotating shaft  21  and a restricting block  22  that are arranged on the two ends of the trigger respectively. The rotating shaft  21  has an axis  210 . The starting switch  2  is pivotally mounted on the handle portion  13  by the rotating shaft  21  as shown in  FIG. 8 . Referring to  FIGS. 3 and 4 , the locking switch device  4  is mounted above the starting switch  2  and comprises a first button component  41  and a second button component  42 . The locking mechanism that is interposed between the locking switch device  4  and the starting switch  2  comprises a first abutting portion  411  and a second abutting portion  421 , and a first block  23  and a second block  24  formed on the starting switch  2 , as shown in  FIGS. 5-7 . The first and second abutting portion  411 ,  421  are respectively formed on the lower ends of the first and second button component  41 ,  42 , and have a generally inverted “L” shape, and are respectively locked and clamped to the first and second block  23 ,  24 , thereby locking the starting switch  2  in the switch-off position. In the switch-off state shown in  FIG. 4 , the pivoting movement of the starting switch  2  about the axis  210  is stopped by the first and second button component  41 ,  42  because of the clamping connection between the first and second abutting portion  411 ,  421  and the first and second blocks  23 ,  24 . In this case, the starting switch  2  cannot be pressed down, thus it avoids operation of the device resulting from a pressing down of the starting switch  2  accidentally by the user. When the locking switch device  4  is operated, the first and second abutting portions  411 ,  421  move to disengage from the first and second blocks  23 ,  24 , whereupon the starting switch  2  can be pressed down. At this moment, the starting switch  2  can be pivoted about the axis  210  towards the interior of the housing  1  so as to start the motor. 
         [0023]    As shown in  FIGS. 1 and 2 , the first and second button components  41 ,  42  are formed with a first button  410  and a second button  420  respectively. As shown in  FIG. 2 , the first and second buttons  410  and  420  project outwardly from the two sides of the handle portion  13  at the position adjacent to the lower end and are close to the starting switch  2 . When the user handles the handle portion  13 , his thumb is able to be positioned on the first button  410  or the second button  420  with his other fingers being able to be on the starting switch  2 . As will be appreciated, such an arrangement enables both left-handed and the right-handed operators to operate and control the reciprocating saw very easily. 
         [0024]    As shown in  FIGS. 3-6 , a linkage mechanism is arranged between the first button  410  and the second button  420 . The linkage mechanism functions such that, once one of the first and second buttons  410 ,  420  is pressed down, the other of the buttons is caused to retract, i.e., move inwardly towards the housing, automatically so as to also achieve a pressed down state. This mechanism thus eliminates the uncomfortable feeling of handling that was found in the prior art. More particularly, the linkage mechanism comprises a first spring  43 , a second spring  44  and two gear-rack transmission pairs. In other embodiments, the first and second springs  43 ,  44  may take the form of other suitable resilient members. The first and second springs  43 ,  44  act between the first and second buttons  410 ,  420 , so that the first and second buttons  410 ,  420  tend to move oppositely. The two gear-rack transmission pairs comprise a gear  45  and two racks which are the first and second racks  412 ,  422  respectively formed on the first and second buttons  41 ,  42 . 
         [0025]    The first and second button components  41  and  42  comprise a first component body  413  and a second component body  423  respectively. The first and second buttons  410 ,  420  and a first and second installation projection  414 ,  424  are arranged on the two ends of the first and second component bodies  413 ,  423  respectively. The first and second component bodies  413 ,  423  have a first through-hole  415  and a second through-hole  425  respectively which are generally rectangular holes. The first and second racks  412 ,  422  are arranged in the lower side of the first through-hole  415  and the upper side of the second through-hole  425  respectively, and the gear teeth face oppositely. The gear  45  engages with the first and second racks  412 ,  422  simultaneously. 
         [0026]    As shown in  FIGS. 3 ,  4  and  8 , in the assembled state, the gear  45  traverses through the first and second through-holes  415  and  425 , and engages with the first and second racks  412 ,  422  simultaneously. The gear  45  has a gear shaft  450  with two ends mounted into a first and second shaft sleeves  46  and  47 . The locking switch device  4  is supported in the housing  1  by the first and second shaft sleeves  46  and  47 . 
         [0027]    The first and second buttons  410 ,  420  have a hollow housing shape and are provided with a first groove  416  and a second groove  426  respectively. The two grooves are respectively shown in  FIGS. 5 and 6 . In the assembled state, the first spring  43  is mounted between the first groove  416  and the second installation projection  424 , and the second spring  44  is mounted between the second groove  426  and the first installation projection  414 . Thus, under the action of the biased pressure of the first and second springs  43 ,  44 , the first and second button components  41 ,  42  tend to move towards the opposite directions. When there is no outer force acting on the first and second buttons  410 ,  420 , the two buttons are urged to extend out of the handle portion  13 . 
         [0028]    As shown in  FIG. 4 , when the user overcomes the biased pressure of the first spring  43  to press down the first button  410 , the first rack  412  moves towards the interior of the housing  1  in the direction A and causes the gear  45  to rotate in a counter-clockwise direction. Since the gear  45  engages with the second rack  422  at the same time, the gear  45  then causes the second rack  422  to move automatically towards the interior of the housing  1  in the direction B by overcoming the biased pressure of the second spring  44 . In contrast, when the user overcomes the biased pressure of the second spring  44  to press down the second button  420 , the second rack moves towards the interior of the housing  1  in the direction B and causes the gear  45  to rotate in a counter-clockwise direction. Since the gear  45  engages with the first rack  412  at the same time, the gear  45  then causes the first rack  412  to move automatically towards the interior of the housing  1  in the direction A by overcoming the biased pressure of the first spring  43 . 
         [0029]    Consequently, no matter which one of the first and second buttons  410 ,  420  is pressed down by the user, the other one of the first and second button  410 ,  420  will move automatically towards the interior of the housing  1  to reach a position corresponding to a state of being pressed down. When the user releases the first button  410  or the second button  420  of the locking switch device  4 , the restoring forces of the first and second spring  43 ,  44  bring the first and second buttons  410 ,  420  to automatically restore the buttons to the un-pressed state. This arrangement enables both the left-handed and the right-handed operators to manipulate the locking switch device very easily. Another advantage of this structure is that, when the user handles the handle portion  13  with his thumb located on one of the first and second buttons  410 ,  420  whereby the other one of the first and second buttons  410 ,  420  will be located in a position corresponding to the palm of the user, when the user presses down one button, the other one will move automatically towards the interior of the housing to reach the position of being pressed down, thus eliminating the uncomfortable feeling of handling the handle and conforming to the principles of the human engineering much better. 
         [0030]      FIGS. 9 and 10  illustrate the further exemplary embodiment of a locking mechanism. In this embodiment, the linkage mechanism between the first and second buttons  410 ,  420  takes the form of a link mechanism. The link mechanism comprises a first link  81 , a second link  82 , and a sliding block  83 . The first link  81  is pivotally connected to the first button  410  and the sliding block  83 , and the second link  82  is pivotally connected between the second button  420  and the sliding block  83 . The sliding block  83  can move upwards and downwards. A restoring member such as a spring  84  acts between the first and second buttons  410  and  420  and causes the first and second buttons  410  and  420  to tend to move oppositely. When there is no outer force acting on the first and second buttons  410  and  420 , the two buttons are urged to extend out of the handle portion  13 . 
         [0031]    When the first button  410  is pressed down in the direction C, the first link  81  connected thereto moves and thus causes the sliding block  83  to move upwards and the sliding block  83  then causes the second link  82  connected thereto to move in the direction D, thereby the angle between the first and second links  81 ,  82  is reduced, and the second button  420  moves towards the housing to reach the position corresponding to a state of being pressed down under the movement of the second link  82 . If the user presses down the second button  420 , the first button will move automatically towards the housing to reach the position corresponding to the state of being pressed down under the action of the link mechanism. Thus, when the user presses down one button of the locking switch device, the other one will move automatically to reach the position of the state of being pressed down. 
         [0032]    The power tool disclosed in the present invention is not limited to the structures shown in the drawings and the above contents. For example, the handle portion of the power tool may be formed onto the housing as a part of the housing, or may be a separate member connected to the housing by a connecting mechanism, and the locking mechanism between the locking switch device and the starting switch may use other structures. The linkage mechanism between the first and second buttons is also not limited to the gear-rack mechanism and link mechanism mentioned above, and other mechanisms, which enable one button to move automatically to be pressed down once the other one is pressed down, may also be used. It will be apparent to those skilled in the art that some changes, substitutes and modifications may be made in the shapes and positions of other members, which are still within the scope of this invention.