Patent Publication Number: US-11047174-B2

Title: Digging apparatus

Description:
This application is a National Stage Patent Application of PCT/CN2018/075276, filed on Feb. 5, 2018, which claims the benefit of priority to European Patent Application No. EP17162856.3, filed on Mar. 24, 2017, the disclosures of all of which are incorporated by reference herein in their entireties. 
     This invention relates to a digging apparatus, and in particular such a digging apparatus suitable, but not exclusively, for digging into soil. 
     Most commercially available digging apparatus include a motor driving a rotatable drilling bit. Some such apparatus only allow one-way drilling, i.e. rotation of the drilling hit in one direction only. They therefore do not allow for reverse rotation of the drilling hit, which is in fact a desirable feature as it helps the drilling bit out of the substrate being drilled or dug, e.g. soil. While some digging apparatus allow choice of drilling direction by pressing a button, it would mean that a user has to press a button every time he/she wants to change the drilling direction of the drilling bit. 
     in addition, most existing mechanisms allowing releasable engagement of drilling bits to a digging apparatus are complex to manufacture and operate, and may also require the use of other tools. Furthermore, most existing digging apparatus have a closed-loop handle. Such a kind of handle suffers from the drawback that, when kickback occurs, a hand or hands of a user may be easily hit by such a closed-loop handle. Moreover, kickback may occur in case of a sudden large torque faced by the drilling bit (and thus the motor), which may hurt the user. A system for preventing or at least mitigating the effect of kickback is thus required. 
     It is thus an object of the present invention to provide a digging apparatus and a digging tool for a digging apparatus in which the aforesaid shortcomings are mitigated, or at least to provide useful alternatives to the trade and public. 
     According to a first aspect of the present invention, there is provided a digging apparatus including a motor, and a digging tool drivenable by said motor, said digging tool having a longitudinal axis, wherein said motor is adapted to selectively drive said digging tool to rotate about said longitudinal axis in a first rotational direction and a second rotational direction which is opposite to said first rotational direction, further including a measuring device for measuring the angular velocity of said digging tool, and a controller for stopping operation of said motor in response to the angular velocity of said digging tool as measured by said measuring device exceeding threshold angular velocity value. 
     According to a second aspect of the present invention, there is provided a digging apparatus including a handle assembly, a motor, a switch member electrically connected with said motor, said switch member being movable between a first position in which operation of said motor is allowed and a second position in which operation of said motor is prevented, and a digging tool drivenable by said motor, said digging tool having a longitudinal axis, characterized in that, when said switch member is in said first position, said motor is adapted to drive said digging tool to rotate about said longitudinal axis in a first rotational direction in response to movement of said handle assembly in a first direction, and said motor is adapted to drive said digging tool to rotate about said longitudinal axis in a second rotational direction which is opposite to said first rotational direction in response to movement of said handle assembly in a second direction which is substantially opposite to said first direction. 
     According to a third aspect of the present invention, there is provided a digging tool for a digging apparatus, said digging tool including a body with a plurality of markings thereon for indicating a depth of penetration of said digging tool into a substrate. 
     According to a fourth aspect of the present invention, there is provided a digging tool for a digging apparatus, said digging tool including a first longitudinal end for penetrating into a substrate, an opposite second longitudinal end for releasable connection with a digging apparatus, and a hollow connection part adjacent said second longitudinal end, wherein said hollow connection part includes two through-holes with their central longitudinal axes aligned with each other. 
    
    
     
       Digging apparatus and a digging tool according to the present invention will now be described, by way of examples only, with reference to the accompany drawings, in which: 
         FIG. 1  is a perspective view of a main body of a digging apparatus according to a first embodiment of the present invention; 
         FIG. 2  is a top view of a handle assembly of the digging apparatus of  FIG. 1 , 
         FIG. 3  is an exploded view of the main body of the digging apparatus of  FIG. 1 ; 
         FIGS. 4A to 4D  show steps of assembling the main body of the digging apparatus of  FIG. 1 ; 
         FIG. 5  is an exploded view of a gear box of the main body of the digging apparatus of  FIG. 1 ; 
         FIG. 6A  is a perspective view of a main body of a digging apparatus according to a second embodiment of the present invention; 
         FIG. 6B  is a perspective view of an adaptor for use with the main body of  FIG. 6A ; 
         FIG. 6C  is a front view of a drilling bit for use with the adaptor of  FIG. 6B ; 
         FIG. 7A  is a side view of a further drilling bit for use with the digging apparatus of  FIG. 1 , and being shown as connected with a part of an engagement mechanism of the main body of the digging apparatus of  FIG. 1 ; 
         FIG. 7B  is an enlarged view of the encircled part marked A of  FIG. 7A , being a part of the drilling bit shown in  FIG. 7A ; 
         FIG. 7C  is a perspective view of an engagement mechanism of the main body of the digging apparatus of  FIG. 1 ; 
         FIG. 7D  is an enlarged view of the encircled part marked B of  FIG. 7A , showing the releasable connection between the drilling bit and the engagement mechanism of the main body of the digging apparatus of  FIG. 1 ; 
         FIG. 8  is a schematic electrical connection diagram of the digging apparatus of  FIG. 1 ; 
         FIG. 9  is a schematic diagram of an anti-kicking module in the electrical connection diagram of  FIG. 8 ; 
         FIG. 10  is a logic control diagram of the anti-kickback function of the schematic electrical connection diagram of  FIG. 8 ; and 
         FIG. 11  is a perspective view of a digging apparatus according to a second embodiment of the present invention. 
     
    
    
       FIG. 1  shows a perspective view of a main body  12  of a digging apparatus according to a first embodiment of the present invention, generally designated as  10 . The main body  12  includes a handle assembly  14  at one longitudinal end thereof and an output shaft  16  at an opposite longitudinal end thereof. As will be discussed below, one longitudinal end of the output shaft  16  is connected with a motor of the digging apparatus  10  and an opposite longitudinal end of the output shaft  16  is releasably connected with a digging tool, such as a drilling bit. The main body  12  has a central longitudinal axis L-L. 
       FIG. 2  shows a top view of the handle assembly  14  of the digging apparatus  10 . The handle assembly  14  is in a generally S-shape, and has two handle portions  18   a ,  18   b , each with a respective free end  20   a ,  20   b  pointing towards generally opposite directions. As mentioned above, most existing digging apparatus have a closed-loop handle, and such a kind of handle suffers from the drawback that, when kickback occurs, a hand of a user or hands may be easily hit by such a closed-loop handle. With the S-shaped handle assembly  14  of the present invention, however, in addition to be grasped easily, when kickback occurs, a user can easily let loose of the handle assembly  14  from the free ends  18   a ,  18   b , thus not having to withstand the kickback force, and reducing the risk of being hurt by the digging apparatus  10 . 
     A main switch  22  is provided on the handle portion  18   a , to be manually operable by a user. The main switch  22  may be moved between an “ON” position and an “OFF” position. When the main switch  22  is in the “OFF” position, the motor (to be discussed below) of the digging apparatus  10  is prevented from being operated. When the main switch  22  is in the “ON” position, the motor of the digging apparatus  10  may be operated upon activation of a switch mechanism to be discussed below. 
     As shown in  FIG. 3 , the handle assembly  14  of the main body  12  includes an upper handle part  24  and a lower handle part  26 , with the main switch  22  including a push button  28  operatively associated with a micro-switch  30  which is electrically connected with a motor  32 , such as a brushed motor. The motor  32  is connected with the output shaft  16  via a gear box  34 . The main body  12  includes a left body housing  36 , a right body housing  38 , a left outer housing  40 , a right outer housing  42 , springs  44 ,  46 , spring holders  48 ,  50 , a first slide switch  52 , and a second slide switch  54 . The motor  32 , the main switch  22  (including the micro-switch  30 ), the first slide switch  52  and the second slide switch  54  are all electrically connected with one another via an electric circuit. The first slide switch  52  and the second slide switch  54  form an auxiliary switch assembly  55 , which co-operates with the main switch  22  in operating the digging apparatus  10 . 
     As shown in  FIGS. 4A to 4D , to assemble the main body  12  of the digging apparatus  10 , the motor  32  and the gear box  34  are connected with each other, and are enclosed within a cavity between the left body housing  36  and the right body housing  38 , with a part of the gear box  34  and the output shaft  16  extending outside the left body housing  36  and the right body housing  38 . The thus assembled portion is then encased between the left outer housing  40  and the right outer housing  42 , again with a part of the gear box  34  and the output shaft  16  extending outside the left outer housing  40  and the right outer housing  42 . The upper handle part  24  and the lower handle  26  part, are then assembled on top of the thus assembled portion to form the main body  12 . 
     As shown in more detail in  FIG. 5 , the gear box  34  of the main body  12  of the digging apparatus  10  includes a pinion adaptor  56  coupled to a pinion  58 , a motor mount  60 , two gear box pins  62 ,  64 , a washer  66 , a first layer planetary gear  68 , a first layer planet carrier  70 , a second layer planetary gear  72 , a first ring gear  74 , a second layer planet carrier  76 , a third layer planetary gear  78 , a second ring gear  80 , a bearing  82 , a retaining ring  84 , and a gear box housing  86 . 
     According to the present invention, a drilling bit is releasably connected with and driven by the motor  32  via the output shaft  16  of the main body  12  to form the digging apparatus  10 . To operate the digging apparatus  10 , the main switch  22  is moved (e.g. by moving the push button  28 ) from the “OFF” position to and remain at the “ON” position to activate the micro-switch  30 . A user holding the handle assembly  14  of the digging apparatus  10  then moves (e.g. pushes) the handle assembly  14  in a direction parallel to the central longitudinal axis L-L of the digging apparatus  10  and from the handle assembly  14  towards the output shaft  16  (and thus towards the drilling bit), as shown by the arrow D in  FIG. 1 . When in use, e.g. when the drilling bit of the digging apparatus  10  abuts or penetrates a substrate to be dug (e.g. soil), as the central longitudinal axis L-L of the digging apparatus  10  extends generally vertically, this direction of movement of the handle assembly  14  is generally downward. Upon movement of the handle assembly  14  in this direction, the first slide switch  52  is activated to close the electric circuit in a configuration in which electricity is supplied to activate the motor  32  to drive the output shaft  16  to rotate in a clockwise direction (when seen from top) to cause the drilling bit to rotate in the same rotational direction, to dig and move downward into the substrate, thus also moving the digging apparatus  10  downward into the substrate. 
     If desired, the user may (while maintaining the main switch  22  in the “ON” position) move (e.g. pull) the handle assembly  14  in a direction opposite to that indicated by the arrow Din  FIG. 1  (i.e. parallel to the central longitudinal axis L-L of the digging apparatus  10  and from the output shaft  16  (or from the drilling bit) towards the handle assembly  14 ). When in use, e.g. when the drilling bit of the digging apparatus  10  penetrates a substrate to be dug (e.g. soil), as the central longitudinal axis L-L of the digging apparatus  10  extends generally vertically, this direction of movement of the handle assembly  14  is generally upward. Upon movement of the handle assembly  14  in this direction, the first slide switch  52  is deactivated, while the second slide switch  54  is activated to close the electric circuit in a different configuration in which electricity is supplied to activate the motor  32  to drive the output shaft  16  to rotate in an opposite, anti-clockwise direction (when seen from top) to cause the drilling bit to rotate in the same rotational direction, to move upward and away from the substrate, thus also moving the digging apparatus  10  upward and away from the substrate. More particularly, when the main switch  22  and the first slide switch  52  are activated, the first slide switch  52  closes the electric circuit in a configuration in which electricity is supplied to the motor  32  in a direction to cause the output shaft  16  of the motor  32  to rotate in the clockwise direction (when seen from top), and when the main switch  22  and the second slide switch  54  are activated, the second slide switch  54  closes the electric circuit in a different configuration in which electricity is supplied to the motor  32  in an opposite direction to cause the output shaft  16  of the motor  32  to rotate in the opposite, anti-clockwise direction (when seen from top). 
     By way of the aforesaid arrangement of the digging apparatus  10  according to the present invention, auto selection of forward/rearward movement of the digging apparatus  10  into and out of the substrate to be dug is allowed. This enables the user to finish the work quicker as there is no need to manually push any button to select the direction of rotation of the drilling bit (and thus the direction of movement of the digging apparatus  10 . Such an auto selection of forward/rearward movement of the digging apparatus  10  also fits in with human habit, as, normally, a user pushes the digging apparatus  10  downward if he/she wants to dig deeper, and the user pulls the digging apparatus  10  upward if he/she wants to retrieve the digging apparatus  10 . Such a feature also allows the user to cause the drilling bit to drill back and forth in the substrate more easily and conveniently, without having to push any button manually. 
     It should be noted that the motor  32  can only operate either when both the main switch  22  and the first slide switch  52  are simultaneously activated, or when both the main switch  22  and the second slide switch  54  are simultaneously activated. Such an arrangement enhances the safety in use of the digging apparatus  10 . Thus, in a way, the main switch  22  acts as a safety switch. 
       FIG. 6A  shows a main body  12   a  of a digging apparatus  10  according to second embodiment of the present invention. The structure of the main body  12   a  is highly similar to that of the main body  12  discussed above, the only difference being the detailed shape of the respective handle assembly  14 ,  14   a . An output shaft  16   a  of the main body  12   a  (with a central longitudinal axis T-T) is releasably connected with a drilling bit  88   a  with a central longitudinal axis P-P, as shown in  FIG. 6C , via an adaptor  90  with a central longitudinal axis S-S, as shown in  FIG. 6B . The adaptor  90  has an upper hollow cylindrical part  92  with two through holes  94  with their central longitudinal axes aligned with each other. The hollow cylindrical part  92  receives part of the output shaft  16   a  of the main body  12   a , and may be releasably connected with the output shaft  16   a  by a lock pin (not shown) going through the through holes  94  and correspondingly positioned through hole (not shown) through the output shaft  16   a . The adaptor  90  also has a lower hollow cylindrical part  96  with two pairs of through holes  98 ,  100 , with their respective pair of central longitudinal axes aligned with each other. An upper end of the  102   a  of the drilling bit  88   a  may be releasably connected with the lower hollow cylindrical part  96  of the adaptor  90  by bolts and nuts, and with possible length adjustment, depending on which pair of aligned holes  98 ,  100  are used. When the drilling bit  88   a  is thus releasably engaged with the main body  12   a , the central longitudinal axis T-T of the main body  12   a , the central longitudinal axis P-P of the drilling bit  88   a  and the central longitudinal axis S-S of the adaptor  90  are aligned with one another. 
       FIG. 7A  shows a drilling bit  88  for use with the digging apparatus  10 , in which the drilling bit  88  is shown as being connected with a part of an engagement mechanism  104  of the main body  12  of the digging apparatus  10 . The drilling bit  88  has a central longitudinal axis M-M which, when the drilling  88  is releasably connected with the engagement mechanism  104 , is aligned with the central longitudinal axis L-L of the main body  12  and of the connection mechanism  104 . To allow the user to easily know the depth to which the drilling bit  88  has penetrated into the substrate (e.g. soil), and as shown in  FIG. 7B , the drilling bit  88  has on its body  106  a number of markings  108  (which may be coloring and/or etchings) to show the distance of the respective markings  108  from a tip  110  of the drilling bit  88 , being one longitudinal end of the drilling bit  88 . 
     The upper end  102  (i.e. the longitudinal end opposite the tip  110 ) of the drilling bit  88  has a hollow connection part  112  with a cavity of a square cross-section sized and configured to receive a part of a male member  114  of the engagement mechanism  104 , which male member  114  also being of a square cross-section. The hollow connection part  112  of the drilling bit  88  has a pair of through holes with their central longitudinal axes aligned with each other. 
     The male member  114  includes two pins  116  with their central longitudinal axes aligned with each other. The pins  116  are movable towards each other to a compressed position and away from each other to an extended position. The pins  116  are biased towards the extended position by a spring  118 . When the drilling bit  88  is connected with the engagement mechanism  104 , in which the male member  114  is received within the hollow connection part  112  of the drilling bit  88 , the pins  116  are in the extended position and are partly received through the through-holes of the hollow connection part  112  of the drilling bit  88  to prevent disengagement of the drilling bit  88  from the engagement mechanism  104 . If desired, the pins  116  may be movable (e.g. by manually compressing the pins  116  towards each other, and against the biasing force of the spring  118 ) to the compressed position, in which the pins  116  are clear of the through holes of the hollow connection part  112  of the drilling bit  88 , to allow disengagement of the drilling bit  88  from the engagement mechanism  104 , thus allowing disconnection of the drilling bit  88  from the main body  12 . 
     Most existing drilling bit locking mechanism makes use of a pin and key. It is time consuming to change the drilling bit. Since the drilling bit is long, it is difficult to align the hole for insertion of the pin and key. There is also the risk of losing the pin or key. On the other hand, the arrangement discussed above allows for easy and convenient connection and disconnection of the drilling bit  88  with and from the main body  12  of the digging apparatus  10 , without requiring the use of any tool or accessory. 
     A schematic electrical connection diagram of the digging apparatus  10  is shown in  FIG. 8 . The digging apparatus  10  is powered by a battery  202 , such as a 18V lithium battery pack. The battery  202  is connected via the micro-switch  30  with a control module  204 , and the control module  204  is connected via the auxiliary switch assembly  55  (which acts as a forward/reverse switch, and including the first slide switch  52  and the second slide switch  54 ) with the motor  32 . Thus, when the micro-switch  30  is operated to close the circuit, the control module  204  is operable to control the operation of the motor  32 . As shown in  FIG. 8 , the control module  204  includes a printed circuit board assembly (PCBA) (i.e. a printed circuit board populated with various electronic components)  206  in electrical and/or data communication with a toggle switch  208  and a gyro sensor device  210 , 
       FIG. 9  is a schematic diagram of the control module  204  in the digging apparatus  10  whose electrical connection diagram is shown in  FIG. 8 , which provides the anti-kickback function. The gyro sensor device  210  measures the angular velocity (also called “palstance”) of the drilling bit  88 ,  88   a , and transmits the relevant measurement data to the PCBA  206 . The PCBA  206  also measures the magnitude of the electric current supplied to (or drawn by) the motor  30 . The toggle switch  208  also includes an LED  212  which acts as a visual indicator of the status of the anti-kickback function. 
       FIG. 10  is a logic control diagram of the anti-kickback function of the digging apparatus  10 . The toggle switch  208  may be moved between a “Switch up” position and a “Switch down” position. When the toggle switch  208  is in the “Switch up” position, the anti-kickback protection function is set at a “Low Level” protection mode in which the gyro sensor device  210  measures the angular velocity of the drilling bit  88 ,  88   a , and the LED  212  is off to visually indicate that the digging apparatus is in the “Low Level” protection mode. In this Low Level protection mode, the PCBA  206  will stop operation of the motor  302  if the electric current supplied to (or drawn by) the motor  30  exceeds a first threshold current value (e.g. 35 A) and the angular velocity of the drilling bit  88 ,  88   a  as measured by the gyro sensor device  210  exceeds a first threshold angular velocity value (e.g. 213° per second). If the toggle switch  208  is moved to the “Switch down” position, the anti-kickback protection function is set at a “High Level” protection mode in which the gyro sensor device  210  measures the angular velocity of the drilling bit  88 ,  88   a  and the LEI)  212  is continuously on to visually indicate that the digging apparatus is in the “High Level” protection mode. In this High Level protection mode, the PCBA  206  will stop operation of the motor  302  if the electric current supplied to (or drawn by) the motor  30  exceeds a second, lower threshold current value (e.g. 10 A) and the angular velocity of the drilling bit  88 ,  88   a  as measured by the gyro sensor device  210  exceeds a second, lower threshold angular velocity value (e.g. 122° per second). In any event, if the operation of the motor  30  is stopped by the PCBA  206  of the control module  204  in response to the angular velocity of the drilling bit  88 ,  88   a  as measured by the gyro sensor device  210  exceeding the currently set threshold angular velocity value and the electric current supplied to the motor  30  exceeding the currently set threshold current value, the LED  212  will flash to visually indicate activation of the protection function. 
     It can be seen that, in addition to providing anti-kickback protection function (by virtue of the operation of the motor  32  being stopped in response to a sudden large torque faced by the drilling bit  88 ,  88   a , as reflected by the high angular velocity and high electric current drawn), the digging apparatus  10  allows the user to set the protection at a High Level and a Low Level, by operating the toggle switch  208 , which effectively sets the threshold angular velocity and the threshold current value exceeding which the operation of the motor  30  will be stopped. 
     A digging apparatus according to a second embodiment of the present invention is shown in  FIG. 11 , and generally designated as  300 . Similar to the digging apparatus  10  discussed above, the digging apparatus  300  also includes a main body  312 , which houses a motor (not shown). To an upper end of the main body  312  is installed a handle assembly  314  and to a lower end of the main body  312  is releasably installed a digging tool, such as a drilling bit  388 . The drilling bit  388  is operatively associated with and driven by the motor. The handle assembly  314  includes two handle portions  318   a ,  318   b . Differences between the digging apparatus  300  and the digging apparatus  10  include:
         (a) in the digging apparatus  300 , free ends  320   a ,  320   b  of the respective handle portions  318   a ,  318   b  point in a same direction; and   (b) in the digging apparatus  300 , a main switch  322  to be operable manually by a user is provided on an underside of the handle portion  318   b , in the form of a pivot switch. As in the case of the switch  22  in the digging apparatus, the main switch  322  is also movable between an “ON” position and an “OFF” position for operating the motor. The switch  322  is biased (e.g. by one or more springs) towards the “OFF” position.       

     It should be understood that the above only illustrates and describes an example whereby the present invention may be carried out, and that modifications and/or alterations may be made thereto without departing from the spirit of the invention. 
     It should also be understood that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any appropriate sub-combinations.