Abstract:
A compact drilling system capable of improving working efficiency. The drilling system includes a drilling machine and a compressor. A control circuit controls performances of a drill motor in the drilling machine and an air compression motor in the compressor based on the detection result of a pressure sensor that detects a pressure within an air tank provided in the compressor. When one of the motors is activated, the other motor is not allowed to be operated and only when the drill motor is activated, compressed air is supplied from the air tank to the drilling machine. An electrical socket is provided in the compressor. A power cord extending from the drilling machine can be connected to the socket.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to a drilling system including a drilling machine and a compressor to be connected to the drilling machine. The present invention also relates to a compressor used for a power tool such as the drilling machine. 
   A drilling machine for drilling holes into a structure such as a concrete wall or the like is known as disclosed in Laid-open Japanese Utility Model Application Publication No. S62-201642. The drilling machine disclosed in the JP publication includes a main body and a drill bit extending from the main body. The drill bit has a discharge port and an air passageway connected to the discharge port. The main body is also formed with an air passageway connected to the air passageway of the drill bit. The discharge port is formed in the vicinity of a cutting edge for ejecting compressed air from the cutting edge. The air passageway in the main body of the drill machine is connected to an air outlet port of a compressor, so that the compressed air is discharged into the main body and is ejected out of the discharge port of the drill bit. Accordingly, the drill bit as well as the drilled target are cooled, and cut-out concrete dust can be discharged out of a drilled hole. 
   In the conventional drilling system, the rotation of a motor for rotating the drill bit and delivery of the compressed air from the compressor are not linked with each other. Therefore, an operator of the machine must adjust an air-valve provided at the main body or at the compressor in order to deliver the compressed air. Thus complicating operation results. Further, compressed air may be discharged from the discharge port even under the condition that the drilling machine has not been started up. Thus, the compressed air has been consumed uselessly. To this effect, a large capacity compressor capable of generating greater amount of compressed air must be required taking the excessive consumption of the compressed air into consideration. 
   Further, in a construction site or the like in which the drilling machine is frequently used, a temporary power source is set up for allowing electric tools to be used. Since the electric power supplied from the temporary power source is lower than that supplied from a permanent power source, a frequent use of electric tools and the like that consume a large electric power may cause an overcurrent protector to be activated to render the temporary power source inoperative. 
   In the drilling system, each of the drilling machine and the compressor provides a driving unit requiring great amount of electric power. Thus, a simultaneous use of the drilling machine and compressor may cause the overcurrent protector to be activated to stop the supply of the power during drilling work. Further, if two driving units are operated at the same time, operational sound becomes noisy. 
   Further, in the case where the drilling system is used to drill holes for curtain wall anchors, holes are pierced in a sequential manner while the operator moves along the wall surface of a building. In such a case, the drilling system must also be moved. A large-sized compressor involves additional work when the compressor needs to be moved to lower workability. 
   Furthermore, if the drilling machine and the compressor are respectively connected to the temporary power source by means of respective power cords, a workable area is reduced to the length of the shorter power cord. Accordingly, the operator can work only the area dependent on the shorter power cord. In order to enlarge the workable area, a position of the temporary power source needs to be frequently changed. When the longer power cords are used, a workable area centered on one power source can be enlarged. However, cable handling becomes difficult to lower workability. 
   SUMMARY OF THE INVENTION 
   It is therefore, an object of the present invention to provide a compact drilling system capable of providing an improved working efficiency. 
   This and other objects of the present invention will be attained by an improved drilling system including a drilling machine, a compressor, a drill motor drive detection unit, and a control unit. The drilling machine includes an outer frame, a rotation shaft, and a drill motor. The outer frame defines a fluid chamber section and has a compressed fluid inlet section in communication with the fluid chamber section. The rotation shaft is rotatably supported by the outer frame and is formed with a fluid passageway in communication with the fluid chamber section. The rotation shaft has a front end to which a drilling tool is detachably attachable. The fluid passageway is opened at the front end. The drill motor is disposed in the outer frame and is drivingly connected to the rotation shaft for rotating the rotation shaft about its axis. The drilling tool has a front end provided with a cutting edge and is formed with a compressed fluid passage having one end opened to the front end for serving as a fluid ejection port and another end in communication with the fluid passageway when the drilling tool is attached to the rotation shaft. The compressor includes a compression unit, and a connection section. The compression unit generates and stores a compressed fluid. The connection section connects the compression unit to the fluid inlet section for introducing the generated compressed fluid into the rotation shaft. The drill motor drive detection unit detects a driving state of the drill motor. The control unit controls an amount of compressed fluid to be discharged from the compression unit based on the driving state of the drill motor detected by the drill motor drive detection unit. 
   In another aspect of the invention, there is provided a compressor including a fluid compression motor, a compressed fluid tank, a pressure detection unit, a fluid compression motor control unit, a discharge port section, and a socket. The fluid compression motor generates a compressed air. The compressed fluid tank accumulates therein the compressed fluid generated by the fluid compression motor. The pressure detection unit detects a pressure of compressed fluid accumulated in the compressed fluid tank. The fluid compression motor control unit controls the fluid compression motor based on the detection result of the pressure detection unit. The discharge port section discharges generated compressed fluid to outside. A power cord of an external power tool is electrically connectable to the socket for supplying an electric power to the power tool. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings; 
       FIG. 1  is a perspective view showing an arrangement of a drilling system according to a first embodiment of the present invention; 
       FIG. 2  is a cross-sectional view showing a drilling machine of the drilling system according to the embodiment; 
       FIG. 3  is a block diagram showing a control system of the drilling system according to the embodiment; 
       FIG. 4  is a flowchart showing an operational routine in the drilling system according to the embodiment; and 
       FIG. 5  is a flowchart showing another operational routine in a drilling system according to a second embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A drilling system according to a first embodiment of the present invention will be described with reference to  FIGS. 1 through 4 . A drilling system  1  shown in  FIG. 1  mainly includes a drilling machine  2  and a compressor  30 . The drilling system  1  is used for drilling shallow holes in a concrete body or the like to which screws and the like are secured. Throughout the specification, a drilling direction will be referred to as a front direction. 
   The drilling machine  2  shown in  FIG. 2  has a housing  3  serving as an outer frame. A drill bit  22  extends from a front end of the housing  3 . A motor  4  serving as an engine for the drilling machine  2  is accommodated in the housing  3 . An output shaft  5  extends in the front direction from the motor  4 . A fan  6  for cooling the motor  4  is fixed to the output shaft  5 . A handle  7  integrally extends from a lower portion of a rear end of the housing  3 . The handle  7  is provided with a trigger  8 , and a switching circuit  9  connected to the trigger  8  is disposed within the handle  7  for controlling the rotation of the motor  4  in response to the operation of the trigger  8 . A power cord  10  connected to the switching circuit  9  extends from a lower end of the handle  7 . 
   A first wall  11  is positioned in front of the motor  4  and within the housing  3  to rotatably support the output shaft  5 . A second wall  12  is positioned in front of the first wall  11  and within the housing  3 . A rotation shaft  15  extends through the second wall  12  and is rotatably supported by the second wall  12  through a bearing. The second wall  12  and the bearing maintain air-tight arrangement between front and rear sides of the second wall  12 . 
   A first gear  13 A, an intermediate gear  13 B and a second gear  14  are disposed between the first and second walls  11  and  12 . More specifically, an intermediate shaft  25  is rotatably supported by the first and second walls  11  and  12 , and the first gear  13 A and the second gear are concentrically fixed to the intermediate gear. The first gear  13 A is meshedly engaged with the output shaft  5 . The second gear  14  is concentrically fixed to the rear end portion of the rotation shaft  15 , and is meshedly engaged with the intermediate gear  13 B. 
   A third wall  18  is provided at the front end of the housing  3 , and a front end portion of the rotation shaft  15  frontwardly extends through the third wall  18 . The rotation shaft  15  is rotatably supported by the third wall  18  through a bearing. An airtight state is maintained between the front and rear sides of the third wall  18  and the bearing. 
   An air chamber  19  is defined by the housing  3 , second wall  12 , third wall  18  and output shaft  15 . An air passageway  16  is coaxially extends through a front end portion of the rotation shaft  15 , and is open at a front end face of the rotation shaft  15 . A male screw is formed at an outer peripheral surface of the front end portion of the rotation shaft  15 . An air hole  17  radially extends through the rotation shaft  15  for communication between an air chamber  19  and the air passageway  16 . Thus, the air chamber  19  is in communication with the atmosphere only through the air hole  17  and air passageway  16 . 
   A compressed air suction plug  20  is connected to the housing  3  at a position between the second wall  12  and third wall  18  to communicate with the air chamber  19 . An air hose  21  is attached to the compressed air suction plug  20  for supplying a compressed air. Thus, the compressed air supplied via the air hose  21  is passed through the compressed air suction plug  20  and supplied into the air chamber  19 . Then, the compressed air is passed through the air hole  17  and air passageway  16  and finally discharged to the atmosphere. The air hose  21  has a length shorter than that of the power cord  10 . 
   The drill bit  22  has a front end provided with a diamond cutting edge, and has a rear end portion formed with a female screw threadably engagable with the male screw of the rotation shaft  15 . An air passageway  24  is concentrically extends along an entire length of the drill bit  22 . The front end of the air passageway  24  serves as a discharge port  23 , and the rear end of the air passageway  24  is in communication with the air passageway  16  formed in the rotation shaft  15 . Thus, the compressed air supplied from the air passageway  16  is ejected out of the discharge port  23 . 
   The compressor  30  mainly includes a main body  31  and an air tank  32 . The main body  31  accommodates therein a control circuit  33  including a microcomputer shown in  FIG. 3 . The air tank  32  stores compressed air. The compressor  30  can be easily hand-carried from one site to another in terms of its size and weight. The main body  31  includes a drill socket  37  to which the power cord  10  is connectable, a power switch  44  for the drilling machine  2 , and a compressor power cord  43 . An air discharge port  40  is formed at the main body  31 . The air hose  21  is to be coupled to the air discharge port  40 . An electromagnetic valve  38  ( FIG. 3 ) is provided in the main body  31  to serve as a valve for the air discharge port  40 . Further, an air compression motor  39  ( FIG. 3 ) is disposed in the main body  31  for generating compressed air to be stored in the air tank  32 . 
   As shown in  FIG. 3 , the air tank  32  is provided with a pressure sensor  41  for detecting a pneumatic pressure within the tank. The drill socket  37  is provided with a current detector  42  that detects a current. The above detection results are output to the control circuit  33 . 
   The main body  31  further includes a drill relay  34 , a valve relay  35  and an air compression relay  36 , those connected to the control circuit  33 . Thus, these relays  34 ,  35 ,  36  are controlled by the control circuit  33 . The drill relay  34  is adapted to turn ON/OFF of the power supply to the drill motor  4  via the drill socket  37 . The valve relay  35  is adapted to turn ON/OFF of the power supply to the electromagnetic valve  38 . The air compression relay  36  is adapted to turn ON/OFF of the power supply to the air compression motor  39 . 
   In operation, the drilling operation is started with the condition shown in  FIG. 1 . That is, the power cord  10  of the drilling machine  2  is connected to the drill socket  37  of the compressor  30 . The air hose  21  extending from the air discharge port  40  of the compressor  30  is connected to the compressed air suction plug  20  of the drilling machine  2 . The compressor power cord  43  of the compressor  30  is connected to a power source (not shown). In this state, an operator can perform the drilling operation within an imaginary circle centered on a power source (not shown) and having a radius corresponding to the length of the compressor power cord  43  without a need of changing the power source. In addition, the operator can perform the drilling operation within an imaginary circle centered on the compressor  30  and having a radius corresponding to the length of the air hose  21  without moving the compressor  30 . As a result, since the compressor  30  can be easily moved as described above, the operator can perform the drilling operation within a circle centered on the power source (not shown) and having a combined radius obtained by the length of the compressor power cord  43  plus the length of the air hose  21  without a need of changing the position of the power source. 
   The power switch  44  is turned ON in the state where the above-described connections are maintained. In this state, determination cannot be made whether compressed air has been stored in the air tank  32 , so that determination whether the drilling operation that requires the compressed air is possible or not also cannot be made. Therefore, in the initial state, the drill relay  34 , valve relay  35 , and air compression relay  36  are all in OFF state so as to disable all works and operations. 
   A pressure within the air tank  32  is then detected by the pressure sensor  41 . When the detected pressure is higher than a predetermined pressure, the drill relay  34  is turned ON. When the trigger  8  of the drilling machine  2  is pulled in this state, the drilling machine  2  can be activated. On the other hand, if the detected pressure is lower than the predetermined pressure, the air compression relay  36  is turned ON to activate the air compression motor  39 . A pressure within the air tank  32  is detected by the pressure sensor  41  at predetermined time intervals even in the state where the air compression motor  39  is activated. When the detected pressure becomes higher than the predetermined pressure, the air compression relay  36  is turned OFF to stop the sion relay  36  is turned OFF to stop the air compression motor  39 . Thereafter, the drill relay  34  is turned ON to allow the drilling machine  2  to be activated when the trigger  8  of the drilling machine  2  is pulled. 
   If the trigger  8  is pulled under the condition that the air compression relay  36  is in OFF state and the drill relay  34  is in ON state, the switching circuit  9  is turned ON to allow a current to flow into the drill motor  4 , thereby activating the drilling machine  2 . At this time, a current flow is detected by the current detector  42  provided at the drill socket  37 . Based on the detection result, the control circuit  33  turns the valve relay  35  ON to allow a current to flow into the electromagnetic valve  38  to open the air discharge port  40 . Thus, the compressed air in the air tank  32  is delivered to the air hose  21 , so that the air can be discharged out of the discharge port  23  through air passageways  16  and  24 . 
   A current flowing through the drill socket  37  is detected by the current detector  42  at predetermined time intervals even in the state where the drill motor  4  is activated. When the drill motor  4  is stopped and the current detector  42  detects that a current does not flow through the drill socket  37 , the control circuit  33  turns the valve relay  35  OFF to stop the discharge of compressed air. Thereafter, a pressure within the air tank  32  is again detected by the pressure sensor  41 . When the detected pressure is not greater than the predetermined pressure, the air compression relay  36  is turned ON after the drill relay  34  has been turned OFF, so that compressed air is stored in the air tank  32  by the air compression motor  39 . At the time when a pressure within the air tank  32  becomes higher than the predetermined pressure, the air compression relay  36  is turned OFF. The drill relay  34  is then turned ON to start the drilling operation. By repeating the above process, the drilling operation can be performed continuously. 
   The above process will be described based on a flowchart shown in  FIG. 4 . Firstly, the power switch  44  is turned ON as a starting condition. The routine then advances to S 01 . In S 01 , initial setting is performed, that is, confirmation is made that the drill relay  34 , valve relay  35 , and air compression relay  36  are all in OFF state. After the confirmation, the routine proceeds into S 02  where a pressure within the air tank  32  is detected. 
   Based on the detection result in S 02 , determination is made in S 03  whether the pressure within the air tank  32  is higher than the predetermined pressure. When it has been determined that the pressure is not more than the predetermined pressure (S 03 :No), the routine advances to S 04 . In S 04 , the drill relay  34  is turned OFF. At the start time, since all the relays have been turned OFF in S 01 , the drill relay  34  is maintained in OFF state without change. The air compression relay  36  is then turned ON in S 05  to activate the air compression motor  39 , thereby storing compressed air in the air tank  32 . Thereafter, the routine returns to S 02 , where a pressure within the air tank  32  is again detected. A flow A including S 02  to S 05  is repeated until a pressure within the air tank  32  has become higher than the predetermined pressure. 
   In S 03 , when the pressure within the air tank  32  is determined to be higher than the predetermined pressure (S 03 :Yes), the routine advances to S 06  where the air compression relay  36  is turned OFF to stop the air compression motor  39 . After that, the routine advances to S 07  where the drill relay  34  is turned ON to make the drill motor  4  ready for operation. 
   At the time when the drill motor  4  is in ready condition, the routine advances to S 08 , where a current flowing through the drill socket  37  is detected. Based on the detection result, determination is made in S 09  whether a current flows or not, in other words, determination whether the drilling operation of the drilling machine  2  is being performed by the operator or not is made. When it has been determined that the drilling operation is being performed (S 09 :Yes), the routine advances to S 11  where the valve relay  35  is turned ON to open the electromagnetic valve  38 , so that the compressed air is discharged from the air discharge port  40  into the drilling machine  2 . Thereafter, the routine returns to S 08  where a current flowing through the drill socket  37  is again detected. While the drilling machine  2  is operated, a flow C including S 08 , S 09 , and S 11  is repeated. 
   When the determination is made in S 09  that the drilling operation is not being performed, that is, a current does not flow through the drill socket  37  (S 09 :No), the routine advances to S 10  where the valve relay  35  is turned OFF. Thereafter, the routine returns to S 02 . In S 02 , a pressure within the air tank  32  is again detected. In S 03 , when the pressure within the air tank  32  is determined to be not greater than the predetermined pressure, the routine advances to S 04 , where the air compression relay  36  is turned ON after the drill relay  34  has been turned OFF. After that, the routine returns to S 02 . While the drilling machine  2  is not operated, a flow B including S 02 , S 03 , and S 06  to S 10  is repeated. 
   A drilling system according to a second embodiment of the present invention will be described with reference to a flowchart shown in  FIG. 5 . The second embodiment is similar to the first embodiment in terms of a mechanical arrangement. An operational routine S 1  through S 11  is the same as that of S 101  to S 111  of the second embodiment. However, the second embodiment further includes steps S 111  through S 115  because of the following reason. Since deep hole drilling is not assumed in the drilling system  1  according to the above embodiment, the case where a pressure within the air tank  32  falls below the predetermined pressure during drilling operation is not paid attention to. Thus, as a modification to the first embodiment, the flowchart shown in  FIG. 5  includes the case where a pressure within the air tank  32  falls below the predetermined pressure during drilling operation. In the flowchart of  FIG. 5 , since the routine from S 101  to S 111  is the same as the routine from S 01  to S 11  in the flowchart of  FIG. 4 , the description thereof will be omitted. 
   After the valve relay  35  has been turned ON in S 111 , a pressure within the air tank  32  is detected in S 112 . Based on the detection result, determination is made in S 113  whether the pressure within the air tank  32  is greater than a specified value that is sufficient for cooling the drill bit  2 . When the pressure within the air tank  32  is determined to be higher than the specified value (S 113 :Yes), the routine returns to S 108 . When the pressure within the air tank  32  is determined to be not greater than the specified value (S 113 :No), the routine advances to S 114 , where the drill relay  34  is turned OFF. After that, the routine advances to S 115  where the air compression relay  36  is turned OFF to end the operation. If the drilling system  1  is to be operated again, the routine will be started from S 101 . 
   According to the above-described embodiments, compressed fluid can automatically be supplied from the compressor  30  to the drilling machine  2  only at the time when the drilling machine  2  is operated, and an amount of the compressed fluid to be supplied can be adjusted depending on the operational state of the drilling machine  2 . 
   Further, since the drill motor  4  and air compression motor  39 , which are the driving units that consume the most electric power, are not operated simultaneously, maximum electric power consumption can be reduced, and reduced noise generation can result. 
   Further, the compressed air is not wastefully consumed in the compressor  30 , a satisfactory cooling effect can be expected in spite of an employment of a compact compressor. 
   While the invention has been described in detail and with reference to specific embodiments thereof, it would be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention. For example, in the above-described embodiments, whether the drilling machine  2  is running or not is confirmed by detection to the current flowing through the drill socket  37 . Alternatively, however, the operation of the drilling machine  2  may be confirmed based on a voltage change, vibration of the drilling machine  2 , noise or the like.