JP5549867B2 - Combustion screw tightening machine - Google Patents

Description

  The present invention relates to a combustion screw tightening machine.

  Patent Literature 1 discloses a screw tightening machine that tightens a screw using a combustion pressure of combustible gas as a power source. In Patent Document 1, a piston thrust by combustion pressure is used as a power source for lowering the screw until it contacts the workpiece, and an electric motor is used as a power source on the rotation side of the screw. In the screw tightening machine shown in this Patent Document 1, in order to tighten the screw, after the piston reaches the bottom dead center, the piston is locked at the bottom dead center side position by a solenoid, and the bit is rotated by an electric motor. Screw tightening. That is, by locking the piston with a solenoid, the screw can be held in a tightenable state. After completion of screw tightening, the lock was released and the piston was returned to top dead center with a spring.

  Moreover, there exists a combustion type nailing machine shown by patent document 2 as an apparatus using the combustion pressure of combustible gas. In Patent Document 2, the rotational speed of the combustible gas stirring fan is variable, and the rotational speed of the fan is changed according to the nail length and the hardness of the material to be driven to change the combustion energy output, that is, the nail driving force. Specifically, the fan rotation speed is set to a certain value set by the nail length or the like over the whole process from nailing to piston return / scavenging.

WO2008 / 085465 Japanese Patent No. 3651988

  In the configuration shown in Patent Document 1, it is possible to secure a state in which the screw can be tightened for a long time. In addition to the power source of the combustion pressure, the screw rotating electric motor and the screw are disposed on the bottom dead center side. The need for a solenoid that locks into position has increased the number of screw tightening components. In addition, the power for driving the solenoid is required, and the battery becomes large, resulting in an increase in the size of the screwing machine. In the combustion type nailer shown in Patent Document 2, when the fan rotational speed is lowered, the fan rotational speed is low during intake and scavenging, and the scavenging performance is also deteriorated.

  Accordingly, an object of the present invention is to provide a combustion type screw tightening machine that suitably secures a state in which a screw can be tightened and is downsized.

  In order to solve the above problems, the present invention provides a screw tightening machine including an impact mechanism that applies impact force to a screw, and a rotation addition mechanism that applies rotational force to the screw. A cylinder in which a cylinder chamber having an opening is formed, a combustion chamber frame provided in the cylinder and defining a combustion chamber into which fuel is injected together with the opening side of the cylinder, and a cylinder chamber disposed in the cylinder chamber A piston provided with a bit driven by the combustion of the fuel in the combustion chamber and striking the screw and rotating together with the screw, and a position facing the opening of the cylinder, is in contact with the combustion chamber frame A cylinder head that can define the combustion chamber, a fan that is provided in the cylinder head and faces the combustion chamber and is rotatable, and a drive control device that controls rotational driving of the fan, The drive control device The fan is rotated at the time of intake and exhaust into the room, and the rotation speed of the fan is set at the time of intake and at the time of turbulent flow at the time of air-fuel mixture formation in the combustion chamber and combustion in the combustion chamber. Provided is a combustion screw tightening machine that can be lowered or stopped as compared with exhaust.

  According to such a configuration, the combustion speed of the fuel injected into the combustion chamber decreases due to the decrease or stop of the rotation speed of the fan. Along with the decrease in the combustion speed, the pressure increase in the combustion chamber becomes moderate, and the state in which the pressure in the combustion chamber is higher than the atmospheric pressure can be maintained for a long time. Since the piston operates due to the pressure difference between the atmospheric pressure and the pressure in the combustion chamber, the bit provided on the piston is operated by striking the screw and energizing it by keeping the high pressure for a long time. State) can be maintained for a long time. In addition, since the fan normally rotates during intake and exhaust, the intake and exhaust performance does not deteriorate. Therefore, occurrence of incomplete combustion or the like is suppressed, and the injected fuel can be suitably burned.

  In the combustion screw tightening machine having the above configuration. The striking mechanism preferably has an ignition device that faces the combustion chamber and ignites the fuel, and the ignition device preferably operates before the rotation addition mechanism.

  According to such a configuration, a rotational force can be applied to the screw in a state where the screw is urged by the bit, so that the rotation adding mechanism is prevented from operating wastefully.

The rotation addition mechanism includes a motion conversion mechanism that engages with the bit, a rotation-side cylinder having a rotation-side cylinder chamber having an opening, and a rotation-side cylinder provided on the rotation-side cylinder. A rotation-side combustion chamber frame capable of defining a rotation-side combustion chamber into which fuel is injected, and the rotation-side cylinder chamber, which is driven by the combustion of the fuel in the rotation-side combustion chamber, and the motion A rotation side piston having a rod that engages with the conversion mechanism, and a rotation side that is disposed at a position facing the opening of the rotation side cylinder and that can contact the rotation side combustion chamber frame to define the rotation side combustion chamber A cylinder head, a rotation-side fan that is provided in the cylinder head and faces the rotation-side combustion chamber and is rotatable, a rotation-side drive device that rotates the fan, and a rotation that ignites fuel in the rotation-side combustion chamber With side ignition device Preferably it includes a.

  According to such a configuration, since the rotation addition mechanism can be operated by the same power source (fuel) as the striking mechanism, the power source can be unified, the number of components is reduced, and the increase in size is suppressed. be able to.

  According to the combustion type screw tightening machine of the present invention, it is possible to suitably secure a state in which the screw can be tightened and to reduce the size.

The side sectional view (state which has stopped) of the combustion type screw fastening machine concerning a first embodiment of the present invention. The block diagram of the control apparatus which concerns on 1st embodiment of this invention. Sectional drawing which shows the motion conversion mechanism of the combustion type screwing machine which concerns on 1st embodiment of invention. 1 is a side cross-sectional view of a combustion screw tightening machine according to a first embodiment of the present invention (a state at the moment when rotation of a bit starts). 1 is a side cross-sectional view of a combustion screw tightening machine according to a first embodiment of the present invention (a state in which a screw is screwed). The time chart of the combustion type screwing machine which concerns on 1st embodiment of this invention. The graph which shows the relationship between a pressure change in a combustion chamber, and operation | movement of a bit. The block diagram of the control apparatus which concerns on 2nd embodiment of this invention. The time chart of the combustion type screwing machine which concerns on 2nd embodiment of this invention.

  A driving machine 1 according to a first embodiment of the present invention will be described with reference to FIGS. The driving machine 1 mainly includes a housing 2, a handle 3, a magazine 4, a nose portion 5, and a motion conversion mechanism 6. The vertical direction is defined with the direction from the handle 3 toward the magazine 4 as the downward direction, and the horizontal direction is defined with the direction in which the handle 3 and the magazine 4 are extended from the housing 2 in the direction perpendicular to the vertical direction as the right direction. .

  The housing 2 includes a first housing 21, a second housing 22, a cylinder housing portion 23, a first head cover 24, and a second head cover 25. Among the above-described components, the configuration relating to the first housing 21 and the first head cover 24 constitutes a striking mechanism, and the configuration relating to the second housing 22 and the second head cover 25 constitutes a rotational force adding mechanism.

  A first cylinder 7, a first combustion chamber frame 12, a bit 9, a first fan 10, a first fan motor 11, and a first cylinder head 27 are provided in the first housing 21. Yes.

  The first cylinder 7 is formed in a cylindrical shape with an upper opening, and a first cylinder chamber 71a is defined in the cylinder. The first cylinder 7 is accommodated in the first housing 21 so that the axial direction of the cylinder is parallel to the vertical direction. Has been. A seal portion 7 </ b> A that comes into contact with the first combustion chamber frame 12 is provided at the opening peripheral portion of the first cylinder chamber 71 a located on the upper side in the first cylinder 7. In the lower wall portion of the first cylinder 7, a hole 7 a that penetrates the inside and outside of the first cylinder chamber 71 a and through which the bit 9 is inserted is formed. A spring (not shown) for biasing a first combustion chamber frame 12 (described later) downward is provided below the first cylinder 7.

  An exhaust hole 7 b that communicates with an exhaust port (not shown) formed in the first housing 21 and penetrates the inside and outside of the first cylinder chamber 71 a is formed in the lower portion of the first cylinder 7. The exhaust hole 7b is provided with an exhaust check valve (not shown) that allows exhaust to flow only in one direction from the inside of the first cylinder chamber 71a to the outside. Further, an exhaust cover (not shown) is provided on the outer periphery of the first cylinder 7 so as to cover the exhaust hole 7b.

  A first piston 71 and a bumper 72 are accommodated in the first cylinder chamber 71a. The first piston 71 has a substantially disk-shaped cross section perpendicular to the vertical direction. The first piston 71 is in contact with the inner peripheral surface of the first cylinder 7 via a plurality of sealing materials, and the first cylinder chamber 71a is defined as an upper chamber. It is divided into a lower chamber. The position shown in FIG. 1 is the top dead center of the first piston 71, and the upper surface of the first piston 71 is substantially the same as the upper surface of the first cylinder 7. The lower surface of the first piston 71 has a boss shape protruding downward, and a pin 73A extending downward is provided on this boss portion. A substantially cylindrical sleeve 73B extending downward is mounted on the pin 73A.

  The bit 9 has a polygonal cross section (in the present embodiment, a regular hexagon), and the tip (lower end) is shaped so as to be engageable with a screw and penetrates the hole 7a to the outside of the first cylinder chamber 71a. It is extended. The bit 9 is mounted at the rear end (upper end) in the cylinder of the sleeve 73B so as to be rotatable about the axis of the bit 9.

  The bumper 72 is disposed at a lower end portion below the first piston 71 in the first cylinder chamber 71a. Therefore, even when the first piston 71 moves downward, the bumper 72 prevents the first piston 71 and the first cylinder chamber 71a from coming into direct contact with each other. The bumper 72 absorbs the impact of the first piston 71 when a screw 41 described later is driven. The position of the first piston 71 where the bumper 72 and the first piston 71 abut is the bottom dead center of the first piston 71.

  The first combustion chamber frame 12 is configured in a cylindrical shape with upper and lower ends opened, and is arranged to be movable up and down with respect to the first cylinder 7 in a state where the first cylinder 7 is arranged in the cylinder. . A first connecting member (not shown) connected to a push lever 51 described later is integrally connected to the lower portion of the first combustion chamber frame 12. Therefore, the first combustion chamber frame 12 can move up and down relative to the first cylinder 7 integrally with the push lever 51. The inner surface of the first combustion chamber frame 12 is configured to contact the seal portion 7A over the entire inner peripheral surface when the first combustion chamber frame 12 rises against the biasing force of a spring (not shown). Has been. When the first combustion chamber frame 12 is raised, the inner peripheral surface of the first combustion chamber frame 12 and the seal portion 7A are in close contact with each other.

  The first cylinder head 27 is located above the first combustion chamber frame 12 and fixed to the first housing 21. The lower surface portion of the first cylinder head 27 is provided with a seal portion 27A that comes into contact with the upper end portion of the first combustion chamber frame 12, and the seal portion 27A and the inner peripheral surface of the upper end portion of the first combustion chamber frame 12 are in close contact with each other. Thus, the first combustion chamber 21a is formed. Specifically, when the first combustion chamber frame 12 moves upward and the inner peripheral surface of the upper end portion of the first combustion chamber frame 12 and the seal portion 27A are in close contact with each other, the upper surface of the first piston 71 and the first cylinder 7 A first combustion chamber 21 a is defined by the upper surface, the first combustion chamber frame 12, and the lower surface of the first cylinder head 27. The first combustion chamber 21 a is kept airtight by close contact between the seal portion 27 </ b> A and the inner peripheral surface of the upper end portion of the first combustion chamber frame 12 and close contact between the seal portion 7 </ b> A and the first combustion chamber frame 12.

  The first cylinder head 27 is provided with a first fan motor 11 and a first spark plug 29. The first fan motor 11 is disposed so that the rotary shaft 11A is parallel to the vertical direction and the tip of the first fan motor 11 protrudes into the first combustion chamber 21a, and is held by the first cylinder head 27. In the first housing 21, a head switch 37A (FIG. 2) is provided for detecting that a push lever 51 described later is pressed against a workpiece (not shown) and the first combustion chamber frame 12 is at the upper end of the stroke. It has been. The head switch 37A is turned on when the first combustion chamber frame 12 is raised to a predetermined position, and at this time, rotation of the first fan motor 11 and a second fan motor 31 described later is started.

  A first fan 10 is provided below the rotating shaft 11A of the first fan motor 11, and the first fan 10 is disposed in the first combustion chamber 21a.

  The first ignition plug 29 is disposed at the upper part of the first combustion chamber 21a, and can ignite the combustible gas supplied into the first combustion chamber 21a. Further, in the first cylinder head 27, a first fuel passage 27a for introducing a combustible gas supplied from a gas cylinder (not shown) into the first combustion chamber 21a is formed.

  In the second housing 22, a second cylinder 8, a second combustion chamber frame 13, a second fan 32, a second fan motor 31, and a second cylinder head 28 are provided. In addition, since the structure in the 2nd housing 22 is as substantially the same as the structure in the 1st housing 21, the same part is demonstrated easily.

  The second cylinder 8 has a cylindrical shape with an opening on the right side, a second cylinder chamber 81a is defined in the cylinder, and is accommodated in the second housing 22 so that the axial direction of the cylinder is parallel to the left-right direction. Has been. A hole 8 a is formed in the left end portion of the second cylinder 8, and a seal portion 8 </ b> A that contacts the second combustion chamber frame 13 is provided on the outer peripheral surface of the right end portion. An exhaust port 8b is formed in the second cylinder 8, and an exhaust check valve (not shown) is provided. A second piston 81 including a rod 14 and a bumper 82 are accommodated in the second cylinder chamber 81a. The second piston 81 is movable in the left-right direction within the second cylinder chamber 81a. The rod 14 is coaxially connected to the second piston 81 at the right end, and a rack 14A is provided at a predetermined length at the left end portion, and the rack 14A meshes with the motion conversion mechanism 6. The right end portion of the rod 14 is coaxially fixed to the second piston 81. The bumper 82 is provided at the left end portion of the second cylinder chamber 81a in order to reduce the impact of the second piston 81 during operation.

  The second combustion chamber frame 13 is arranged so as to be movable in the left-right direction with respect to the second cylinder 8, and a second connection member (not shown) connected to a push lever 51 described later is integrally connected to the left end portion thereof. ing. The second combustion chamber frame 13 moves in the left-right direction via a connecting member (not shown) in conjunction with the vertical movement of the push lever 51. The second combustion chamber frame 13 is urged to the left side with respect to the second cylinder 8 by a spring (not shown). The second combustion chamber frame 13 and the second cylinder 8 are in close contact with each other by a seal portion 8A.

  The second cylinder head 28 is provided on the right side of the second combustion chamber frame 13, and a seal portion 28A is provided on the left side thereof. The second combustion chamber 22a is defined by the close contact between the seal portion 28A and the second combustion chamber frame 13 and the close contact between the second cylinder 8 and the second combustion chamber frame 13, and the airtightness thereof is maintained.

  The second cylinder head 28 is provided with a second fan motor 31 and a second spark plug 33. Further, the second cylinder head 28 is formed with a second fuel flow path 28a for introducing a combustible gas.

  The cylinder housing part 23 is provided along the vertical direction on the side part of the first housing 21, and has a gas cylinder 80 inside thereof. The gas cylinder 80 stores a combustible gas therein, can eject a certain amount of combustible gas, and moves the first combustion chamber frame 12 and the second combustion chamber frame 13 (movement of a push lever 51 described later). Accordingly, it is configured to incline toward the first cylinder head 27. A gas cylinder (not shown) has its tip connected to the first fuel flow path 27a and the second fuel flow path 28b, and jets combustible gas into the first fuel flow path 27a and the second fuel flow path 28a. Can do.

  The first head cover 24 is provided above the first housing 21 and has a plurality of intake holes 24a. As the first fan 10 rotates, fresh air can be taken into the first combustion chamber 21a from the intake hole 24a.

  The second head cover 25 is provided on the right side of the second housing 22 and has a plurality of intake holes 25a. As the second fan 32 rotates, fresh air can be taken into the second combustion chamber 22a from the intake hole 25a.

  A trigger 36 is provided at a portion where the handle 3 is connected to the cylinder accommodating portion 23, and the trigger 36 operates a trigger switch 36A. A battery 35 is detachably inserted into the handle 3.

  The magazine 4 is provided below the handle 3 and at substantially the same position as the second housing 22 in the vertical direction. A plurality of screws 41 are loaded therein, and the screws 41 are supplied to a nose portion 5 described later by a spring (not shown). A control device 37 is provided inside the magazine 4. The control device 37 is connected to the trigger switch 36A, the head switch 37A, the first spark plug 29, the second spark plug 33, the first fan 10, and the second fan 32, and performs the control related to the striking mechanism. It has the control part 38 and the rotation side control part 39 which performs control which concerns on a rotational force addition mechanism. As shown in FIG. 2, the striking-side control unit 38 includes a first fan drive circuit 38A, a first fan timer 38B, and a first spark drive circuit 38C. A second fan drive circuit 39A, a second fan timer 39B, a second spark drive circuit 39C, and an ignition timer 39D are included.

  The first fan drive circuit 38A is connected to the first fan motor 11 and applies drive power to the first fan motor 11 based on a signal from the first fan timer 38B. The first fan timer 38B detects signals from the head switch 37A and the trigger switch 36A, and the first fan drive circuit 38A for a certain period of time from when all signals from the head switch 37A and the trigger switch 36A are not detected. Is outputting a signal. The first spark drive circuit 38C outputs a signal to the first spark plug 29 and applies drive power when detecting signals from both the head switch 37A and the trigger switch 36A.

  The second fan drive circuit 39A is connected to the second fan motor 31 and outputs a signal to the second fan motor 31 based on a signal from the second fan timer 39B or a signal from at least one of the head switch 37A and the trigger switch 36A. Then, driving power is applied. The second fan timer 39B detects the signals from the head switch 37A and the trigger switch 36A, and the second fan drive circuit 39A for a certain time from when all the signals from the head switch 37A and the trigger switch 36A are not detected. Is outputting a signal. The second spark drive circuit 39C detects signals from both the head switch 37A and the trigger switch 36A, and outputs a signal to the second spark plug 33 to apply drive power when detecting a signal from the ignition timer 39D. ing. The ignition timer 39D detects the signal output from the first spark drive circuit 38C, and then outputs a signal to the second spark drive circuit 39C after a predetermined time t13 (about 15 ms) has elapsed.

  Below the first cylinder 7, a nose portion 5 facing the workpiece P is provided. The nose portion 5 is provided with a push lever 51 that is formed with a guide injection port 5a for a bit 9 and a screw 41 and is movable in the vertical direction. The push lever 51 is connected to a connecting member (not shown). A spring (not shown) is interposed between the push lever 51 and the first first cylinder 7, and the push lever 51 is urged downward with respect to the first cylinder 7 by the spring (not shown).

  The motion conversion mechanism 6 is located between the nose portion 5 and the first cylinder 7 and is composed of a pinion 61, a first gear 62, and a second gear 63 as shown in FIG. . The pinion 61 is always meshed with the rack 14A of the rod 14 and has a shaft 61A that is rotatably supported by the nose portion 5 (FIG. 1). The first gear 62 is coaxially fixed to the shaft 61 </ b> A, rotates coaxially with the pinion 61, and meshes with the second gear 63. The second gear 63 has a hexagonal insertion hole 63a formed at the rotational center position, and the bit 9 is inserted into the insertion hole 63a in a gap fitting state. Therefore, the bit 9 and the second gear 63 rotate coaxially with each other, but the bit 9 can move in the penetration direction (vertical direction) to the insertion hole 63a with respect to the second gear 63.

  As the rod 14 moves in the left-right direction, the pinion 61 meshing with the rack 14A rotates and converts linear motion into rotational motion. The rotational force of the pinion 61 is transmitted to the coaxial first gear 62 via the shaft 61 </ b> A, and is transmitted to the second gear 63 meshing with the first gear 62. Thereby, the rotational force is transmitted to the bit 9 inserted through the insertion hole 63a of the second gear 63. As described above, since the rod 14 and the pinion 61 are always meshed and the bit 9 is inserted into the insertion hole 63a of the second gear 63, the operation amount of the rod 14 is proportional to the rotation amount of the bit 9. . Since the amount of movement of the rod 14 is the amount of movement of the second piston 81, the amount of movement of the second piston 81 and the amount of rotation of the bit 9 are in a proportional relationship. Further, since the second piston 81 can move only from the top dead center to the bottom dead center, the second gear 63 (bits) while the second piston 81 is moving from the top dead center to the bottom dead center. 9) During the rotation.

  The process of driving the screw 41 into the workpiece P with the driving machine 1 having the above-described configuration will be described mainly based on the block diagram of FIG. 2 and the time charts of FIGS. 6 and 7. In the state shown in FIG. 1 in the driving machine 1, since the push lever 51 and the trigger 36 are not operated, the head switch 37A, the trigger switch 36A, the fuel injection, the first fan motor 11, the first spark plug 29, The second fan motor 31 and the second spark plug 33 are both in an off state and are not operating. The first combustion chamber 21a and the second combustion chamber 22a are both open, and the first piston 71 and the second piston 81 are both located at the top dead center.

From the state shown in FIG. 1, at time T0 shown in FIG. 6, the push lever 51 is pushed against the nose portion 5 by pressing the driving machine 1 against the workpiece P as shown in FIG. 4. Move upward. With this movement, the first combustion chamber frame 12 moves upward with respect to the first cylinder 7, closes the first combustion chamber 21a, and turns on the head switch 37A (FIG. 2). Simultaneously with the movement of the first combustion chamber frame 12, the second combustion chamber frame 13 moves to the right with respect to the second cylinder 8, and the second combustion chamber 22a is closed. Since the head switch 37A is turned on, a signal is output from the head switch 37A, which is detected by the second fan drive circuit 39A, the second fan motor 31 is turned on, and the second fan 32 is rotated at about 12000 min ⁻¹ . Let

  Further, in accordance with the operation of the push lever 51, combustible gas as fuel is ejected from the gas cylinder 80 into the first fuel flow path 27a and is also ejected into the second fuel flow path 28a and is closed. The fuel is guided into the inside and the second combustion chamber 22a. Since the second fan 32 is rotating in the second combustion chamber 22a, oxygen (air) and fuel in the second combustion chamber 22a are agitated and mixed in advance, and an air-fuel mixture is suitably formed. On the other hand, in the first combustion chamber 21a, since the first fan 10 has not yet been rotated, oxygen (air) and fuel are not stirred and mixed.

  Next, at time T1, the trigger 36 is pulled and the trigger switch 36A is turned on. At this time, since signals are output from both the trigger switch 36A and the head switch 37A, a signal is output from the first spark drive circuit 38C to the first spark plug 29 based on both signals, and the first Sparks are generated by the first spark plug 29 in the combustion chamber 21a. Simultaneously with the occurrence of the spark, the air-fuel mixture in the first combustion chamber 21a is ignited and the fuel starts to combust. At time T2, the first piston 71 starts moving from the top dead center toward the bottom dead center.

  Further, when a signal is output from the first spark drive circuit 38C, the ignition timer 39D operates, and at time T3 after a predetermined time t13 (about 15 ms) has elapsed from time T1, the second spark drive circuit 38C causes the trigger switch 36A. And the signal from both the head switch 37A and the signal from the ignition timer 39D are detected and the signal is output to the second spark plug 33. Based on this signal, a spark is generated by the second spark plug 33 in the second combustion chamber 22a. Simultaneously with the occurrence of the spark, the air-fuel mixture in the second combustion chamber 22a is ignited and the air-fuel mixture starts to combust, and the second piston 81 moves from the top dead center toward the bottom dead center at time T4 as shown in FIG. Begin to.

  After that, as shown in FIG. 4 at time T5, the bit 9 brings the nail 41 into contact with the driven material P, and at time T6, the first piston 71 and the second piston 81 are brought into contact with each other as shown in FIG. It reaches the bottom dead center almost at the same time.

  Combustion in the first combustion chamber 21a from time T1 is combustion in a state where the air-fuel mixture is not suitably formed, and therefore the combustion speed is slow, so that rapid volume expansion does not occur. Therefore, as shown in the graph (a) of FIG. 7, a rapid increase in the combustion pressure does not occur, and the pressure gradually increases from time T1, and the maximum value of the combustion pressure is excessively increased. It does not become high pressure. Therefore, as shown in the graph (b), the time (t26: about 20 ms) from the top dead center to the bottom dead center of the bit 9 becomes long.

  On the other hand, since the combustion in the second combustion chamber 22a from time T3 is combustion in a state in which a suitable air-fuel mixture is formed, the combustion speed is fast and rapid volume expansion occurs. Therefore, as shown in the graph (a) of FIG. 7, the combustion pressure suddenly rises, and the maximum value is higher than that of the first combustion chamber 21a. Therefore, the movement from the top dead center to the bottom dead center of the second piston 81 is faster than the movement from the top dead center to the bottom dead center of the first piston 71. Therefore, even if the time required for the movement from the top dead center to the bottom dead center of the second piston 81 is t46 (about 10 ms) and the movement start time T4 is later than the movement start time T2 of the first piston 71, the same time T6 Can be moved to the bottom dead center. Since the ignition time at the second spark plug 33, which is the basis for the movement of the second piston 81, can be changed by setting the ignition timer 39D, the first piston 71 and the second piston are determined by calculating the optimum value in advance through experiments. It is easy to set 81 to move to the bottom dead center at the same time.

  Generally, in the case of screw tightening, since the workpiece penetrates by the biting of the helical thread by the rotation of the screw, the urging force (thrust) from the bit 9 to the screw 41 is the force of the screw head of the bit 9 and the screw 41. A small load that does not disengage the cross hole is sufficient. Therefore, even if the maximum value of the combustion pressure is small in the first combustion chamber 21a as described above, the contact of the bit 9 with the screw 41 is preferably performed.

  In addition, it is necessary to lower the screw 41 to a position where it comes into contact with the workpiece P before the rotation starts. However, as described above, the ignition timing is shifted and the first piston 71 is moved before the rotation of the bit 9. Therefore, the screw 41 urged by the bit 9 can be brought into contact with the driven material P at time T5 when the second piston 81 starts to move and the amount of rotation of the bit 9 starts to increase.

  After the screw 41 comes into contact with the workpiece P, the screw 41 penetrates into the workpiece P by further rotation. The penetration of the screw 41 advances in the axial direction due to the rotation, but due to the inertial resistance of the gears of the motion conversion mechanism 6, the time required for the penetration of the screw 41 is, for example, from the penetration of the nail by the nailing machine only by the reciprocation of the piston take time. For this, as described above, the combustion pressure in the second combustion chamber 22a is increased to increase the moving speed of the second piston 81 (the rotational speed of the bit 9) and the combustion in the first combustion chamber 21a. The pressure is lowered to lower the moving speed of the first piston 71 (moving speed of the bit 9). As a result, it is possible to earn time to continue to urge the screw 41 with the bit 9 after the screw 41 comes into contact with the workpiece P, so that while the screw 41 is inserted, that is, until the bit 9 is completely turned. While the second piston 81 moves from the top dead center to the bottom dead center, the screw 41 can be continuously urged by the bit 9.

  After the first piston 71 comes into contact with the bumper 72 (after the penetration of the screw 41), the combustion gas is discharged to the outside of the first cylinder 7 through the exhaust hole 7b. When the combustion gas is released to the outside of the first cylinder 7 and the inside of the first cylinder chamber 71a and the inside of the first combustion chamber 21a become atmospheric pressure, the check valve (not shown) of the exhaust hole 7b is closed. Similarly, in the second combustion chamber, the combustion gas is discharged to the outside of the second cylinder 8 through the exhaust port 8b, and is illustrated when the inside of the second cylinder chamber 81a and the inside of the second combustion chamber 22a become atmospheric pressure. The check valve is closed.

  The combustion gas remaining in the first cylinder chamber 71a, the second cylinder chamber 81a, the first combustion chamber 21a, and the second combustion chamber 22a is at a high temperature because it is after combustion, and the combustion heat is the first cylinder 7. And it absorbs from the wall of the 2nd cylinder 8, the 1st combustion chamber frame 12, and the 2nd combustion chamber frame 13, and the 1st cylinder 7, the 2nd cylinder 8, etc. become high temperature. The absorbed heat is dissipated into the atmosphere from the first cylinder 7 and the second cylinder 8 and the outer surfaces of the first combustion chamber frame 12 and the second combustion chamber frame 13.

  The first cylinder 7 absorbs the combustion heat of the combustion gas, so that the combustion gas is rapidly cooled, the volume of the combustion gas is reduced, the pressure in the upper chamber of the first piston 71 is lowered, and a thermal vacuum that becomes below atmospheric pressure. The first piston 71 is pulled back to the initial top dead center position. Similarly, in the second combustion chamber 22a, a thermal vacuum state is established, and the second piston 81 is pulled back to the top dead center position.

  Thereafter, at time T7, pulling of the trigger 36 is stopped and the trigger switch 36A is turned off. When the screw tightening machine 1 is further lifted at time T8 and the push lever 51 is separated from the workpiece P, the push lever 51, the first combustion chamber frame 12 and the second combustion chamber frame 13 are energized by a spring (not shown). To return to the initial position shown in FIG. When the first combustion chamber frame 12 returns to this initial position, the head switch 37A is also turned off. Based on the off signal of the trigger switch 36A and the off signal of the head switch 37A, the first fan timer 38B and the second fan timer 39B operate for a predetermined time (t89: about 10 s) and output signals.

By detecting the outputs from the first fan timer 38B and the second fan timer 39B by the first fan drive circuit 38A and the second fan drive circuit 39A, the first fan 10 and the second fan 32 rotate for the predetermined time. Continue to rotate at a number (about 12000 min ⁻¹ ). At this time, an air flow is generated by the first fan 10 and the second fan 32 through the first vent hole 21b above the first combustion chamber frame 12 and the third vent hole 22b on the right side of the second combustion chamber frame 13. Thus, clean air is taken in (intake air) from the intake holes 24a and 25a provided in the first head cover 24 and the second head cover 25, respectively, and air after combustion is discharged from an exhaust port (not shown) of the housing 2 (exhaust gas). ). Thereafter, when a predetermined time elapses at time T9, the first fan 10 and the second fan 32 are stopped to be in an initial stationary state. After the stationary state, the screw 41 can be driven again by repeating the above process again.

  Next, a second embodiment of the present invention will be described with reference to FIGS. Since the screw tightening machine according to the second embodiment is the same as the screw tightening machine 1 according to the first embodiment except for the configuration related to the control device 137, the description thereof is omitted.

  The control device 137 is connected to the trigger switch 36A, the head switch 37A, the first spark plug 29, the second spark plug 33, the first fan 10, and the second fan 32 as shown in FIG. A striking-side control unit 138 that performs the control according to the above, and a rotation-side control unit 139 that performs control according to the rotational force addition mechanism.

  The striking-side control unit 138 includes a first fan drive circuit 138A, a first fan timer 138B, a first spark drive circuit 138C, and a voltage conversion circuit 138D. The rotation-side control unit 139 includes a second fan drive circuit 139A, a second fan timer 139B, a second spark drive circuit 139C, and an ignition timer 139D. The rotation-side control according to the first embodiment. Since the configuration is the same as that of the unit 39, the description is omitted.

The first fan drive circuit 138A is connected to the first fan motor 11 and based on a signal from the voltage conversion circuit 138D, the first fan motor 11 is supplied with a voltage of low speed rotation (about 600 min ⁻¹ ) and high speed rotation (about 12000 min ⁻¹ ). The voltage is applied. The first fan timer 138B detects signals from the head switch 37A and the trigger switch 36A, and also outputs a signal to the voltage conversion circuit 138D for a certain period of time after all signals from the head switch 37A and the trigger switch 36A are not detected. Is output. The first spark drive circuit 138C outputs a signal to the first spark plug 29 and applies drive power when detecting signals from both the head switch 37A and the trigger switch 36A. The voltage conversion circuit 138D outputs a first voltage and signal to the first fan drive circuit 138A based on a signal from at least one of the head switch 37A and the trigger switch 36A, and based on a signal from the first fan timer 138B. The second voltage and signal are output to the first fan drive circuit 138A. Here, the first voltage is a signal at which the first fan motor 11 rotates at a low speed, and the second signal is a voltage at which the first fan motor 11 can rotate at a high speed.

  The process of driving the screw 41 into the workpiece P by the control device 137 will be described based on the block diagram of FIG. 8 and the time chart of FIG. Since the operation of the screw driving machine at each time (T0 to T9) is substantially the same as the operation at each time of the screw driving machine 1 according to the first embodiment, differences will be mainly described.

As shown in FIG. 9, at time T0, fuel is injected into the first combustion chamber 21a and the second combustion chamber 22a and the head switch 37A is turned on, so that a signal is output from the head switch 37A. Is detected by the second fan drive circuit 139A, the second fan motor 31 is turned on, and the second fan 32 is rotated at about 12000 min ⁻¹ . Similarly, the signal of the head switch 37A is detected by the voltage conversion circuit 138D. Based on the detection result, the voltage conversion circuit 138D outputs the first voltage and signal to the first fan drive circuit 138A. Rotate at low speed. Due to the rotation of the second fan motor 31, a suitable air-fuel mixture is formed in the second combustion chamber 22a. On the other hand, since the first fan motor 11 rotates at a low speed in the first combustion chamber 21a, a suitable air-fuel mixture is not formed.

  Next, at time T1, the trigger 36 is pulled and the trigger switch 36A is turned on. At this time, since signals are output from both the trigger switch 36A and the head switch 37A, a signal is output from the first spark drive circuit 138C to the first spark plug 29 based on both signals, and the first Sparks are generated by the first spark plug 29 in the combustion chamber 21a. Simultaneously with the occurrence of the spark, the air-fuel mixture in the first combustion chamber 21a is ignited and the fuel starts to combust. At time T2, the first piston 71 starts moving from the top dead center toward the bottom dead center.

  Combustion in the first combustion chamber 21a from time T1 is combustion in a state in which the air-fuel mixture is not suitably formed. Therefore, the combustion speed is slow as in the first embodiment, and the top dead center of the bit 9 is reached. The time from the point to the bottom dead center, in particular, the time from when the screw 41 contacts the workpiece P to the bottom dead center becomes longer. Thereby, a biasing force can be applied to the screw 41 from the bit 9 for a long time.

  At time T8 when both the trigger switch 36A and the head switch 37A are turned off, a signal detected by the voltage conversion circuit 138D is a signal from one of the trigger switch 36A and the head switch 37A, and a signal from the first fan timer 138B. Switch to. When the signal from the first fan timer 138B is detected by the voltage conversion circuit 138D, the voltage conversion circuit 138D outputs the second voltage and signal to the first fan drive circuit 138A, and the first fan motor 11 is driven at high speed. Rotate. As the first fan motor 11 rotates at high speed, the exhaust and intake air in the first combustion chamber 21a can be suitably performed between the time T8 and the time T9 to prepare for the next driving operation.

In the first embodiment, the first fan 10 is not rotated during the periods T0 to T8, and the first fan 10 is rotated during the periods T8 to T9. In this case, the combustion speed in the first combustion chamber 21a in the periods T0 to T8 is slow, but the combustible gas is burned with little mixing with the air in the first combustion chamber 21a, so the periods T8 to T9. In this case, a part of the combustible gas may be exhausted as unburned gas. On the other hand, in the second embodiment, since the first fan 10 is rotated at a low speed (approximately 600 min ⁻¹ ) in the periods T0 to T8, the combustion gas and air are mixed to some extent. Thereby, combustion performance improves from 1st embodiment and it is suppressed that unburned gas is generated. In the second embodiment, the low-speed rotation is performed in the periods T0 to T8. However, the rotation is not limited to this. For example, from the period T1 to T8 (from when the first ignition plug 29 is ignited to before intake and exhaust are performed) ), The first fan 10 may be rotated at a low speed, and conversely, the first fan 10 may be rotated at a low speed only during the period T0 to T1 (from when the combustion gas is injected until the first spark plug 29 is ignited). You may let them.

In the second embodiment, although the low speed (600 min ^-1) with respect to high-speed rotation (12000min ^-1), not limited to this, the shape of the screw driver, the type of screw to be symmetrical like It can be changed as appropriate.

1 .... Driver 2 .... Housing 3 .... Handle 4 .... Magazine 5 .... Nose part 5a ... Guide injection port 6 .... Motion conversion mechanism 7 .... First cylinder 7A ... Seal part 7a ... 7b..Exhaust hole 8..Second cylinder 8A..Seal 8a..Hole 8b..Exhaust port 9..Bit 10..First fan 11..First fan motor 11A..Rotating shaft 12 .... First combustion chamber frame 13 ··· Second combustion chamber frame 14 ··· Rod 14A · · Rack 21 · · First housing 21a · · First combustion chamber 22 · · Second housing 22a · · Second combustion chamber 23 ··· Cylinder housing part 24 .. First head cover 24 a ..Intake hole 25 ..Second head cover 25 a ..Intake hole 27 ..First cylinder head 27 A..Seal part 27 a .. First fuel flow path 28. Cylinder head 28A ... 28a, second fuel flow path 28b, second fuel flow path 29, first spark plug 31, second fan motor 32, second fan 33, second spark plug 35, Battery 36 ·· Trigger 36A · · Trigger switch 37 · · Control device 37A · · Head switch 38 · · Strike side control unit 38A · · First fan drive circuit 38B · · First fan timer 38C · · First spark drive circuit 39..Rotation side control unit 39A..Second fan drive circuit 39B..Second fan timer 39C..Second spark drive circuit 39D..Ignition timer 41..Screw 51..Push lever 61..Pinion 61A. · Shaft 62 · · First gear 63 · · Second gear 63a · · Insertion hole 71 · · First piston 71a · · First cylinder chamber 72 · · Bumper 73A · · Pin 73B · · Sleeve 80 · Gas cylinder 81 .. The second piston 81a ... second cylinder chamber 82 ... bumper

Claims (3)

A striking mechanism that adds striking force to the screw;
A screwing machine comprising a rotation adding mechanism for applying a rotational force to the screw,
The striking mechanism includes a cylinder in which a cylinder chamber having an opening is formed;
A combustion chamber frame provided in the cylinder and capable of defining a combustion chamber into which fuel is injected together with the opening side of the cylinder;
A piston disposed in the cylinder chamber and driven by the combustion of the fuel in the combustion chamber and having a bit that strikes the screw and rotates together with the screw;
A cylinder head disposed at a position facing the opening of the cylinder and capable of defining the combustion chamber in contact with the combustion chamber frame;
A fan provided in the cylinder head and facing the combustion chamber and rotatable;
A drive control device for controlling the rotational drive of the fan,
The drive control device rotates the fan at the time of intake and exhaust to the combustion chamber, and sets the rotation speed of the fan at the time of air-fuel mixture formation in the combustion chamber and combustion in the combustion chamber. Combustion type screw tightening machine characterized in that it is lowered or stopped as compared to the time of exhaust and exhaust. The striking mechanism has an ignition device that faces the combustion chamber and ignites the fuel,
The combustion type screw tightening machine according to claim 1, wherein the ignition device operates prior to the rotation adding mechanism. The rotation adding mechanism includes a motion conversion mechanism that engages with the bit;
A rotation-side cylinder in which a rotation-side cylinder chamber having an opening is formed;
A rotation-side combustion chamber frame that is provided in the rotation-side cylinder and that can define a rotation-side combustion chamber in which fuel is injected together with the opening side of the rotation-side cylinder;
A rotation-side piston that is disposed in the rotation-side cylinder chamber and is driven by combustion of the fuel in the rotation-side combustion chamber and includes a rod that engages with the motion conversion mechanism;
A rotation-side cylinder head that is disposed at a position facing the opening of the rotation-side cylinder and is capable of defining the rotation-side combustion chamber in contact with the rotation-side combustion chamber frame;
A rotation-side fan that is provided in the cylinder head and faces the rotation-side combustion chamber and is rotatable;
A rotation side driving device for rotating the fan;
The combustion screw tightening machine according to claim 1, further comprising: a rotation side ignition device that ignites fuel in the rotation side combustion chamber.

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