1. Field of the Invention
The present invention relates to a fastener driving tool for fastening a fastener such as a nail, rivet, or staple to a member to be fastened.
2. Description of the Related Art
In the related art, spring-driven type fastener driving tools employing electric motors are well-known. This type of spring-driven type fastener driving tool uses the drive power of an electric motor to push up a plunger urged by a spring in a direction from a lower dead point to an upper dead point in a fastening direction in resistance to urging force of the spring. The fastener such as a nail is then accelerated in a direction from the upper dead point to the lower dead point by a plunger as a result of the plunger that has been pushed up being released and the fastener is fastened to a member to be fastened.
An electric motor built into a spring-driven type fastener driving tool of the related art drives the plunger from an upper dead point side to an end a position while compressing a spring in resistance to the urging force of the spring using a reduction mechanism provided at a rotation output axis side.
With spring-driven fastener driving tools, in a state of transition after fastening a fastener, the spring is compressed by rotation inertia of a reduction mechanism unit that includes the rotor of a motor and a reduction gear even after a voltage is no longer applied to the electric motor. This means that a mechanism is also required to prevent movement of the plunger in a direction for fastening the fastener as a result of the compressed force of the spring and for preventing movement in the opposite direction to the direction of fastening. Typically, a one-way clutch (reverse rotation prevention mechanism) is provided that prohibits reverse rotation of the rotation output axis of the reduction mechanism unit using urging force (compression force) of the spring when rotation of the motor is stopped.
However, when a spring-driven type fastener driving tool that fastens, for example, larger nails of a length of, for example, 65 millimeters is designed, it is necessary to supply substantial striking power (driving power) to the plunger. It is therefore necessary to make the coil diameter in the spring steel wire diameter of the coil spring large and it is necessary to make urging force (spring force) of the spring with respect to the plunger substantial. However, when the spring force is made large, the drive time taken to move the plunger to the upper dead point becomes substantial. In this event, for example, a time difference occurs between a switch operation time of a trigger switch etc. that permits the firing of a fastening nail and a fastening firing time with a fastener that carries out firing operation that fires a nail every time a nose (push switch) is pressed against a member to be fastened while pulling the trigger switch. This presents a problem that the fastening feeling in response to the fastening switch operation is poor.
In order to resolve this problem, a reduction mechanism unit that reduces high-speed rotation at the motor is connected and a one-way clutch is provided for the reduced rotation output. However, when reverse rotation with respect to the reduction rotation axis is prevented by the urging force of a spring, it is necessary to increase the required allowable torque at the one-way clutch resisting the spring force. This means that a one-way clutch that becomes larger as the spring becomes larger is required. The dimensions and weight of the one-way clutch therefore increase as do the manufacturing costs.
In order to resolve the above situation, it is an object of the present invention to provide a fastener driving tool that can be both small and lightweight because it is not necessary to increase the allowable torque at the one-way clutch.
In order to achieve the above object, a fastener driving tool of the present invention comprises a motor having a first rotation output shaft, a magazine that supplies fasteners, a plunger, provided to move up and down between an upper dead point and a lower dead point, and having a blade for driving in the fasteners, a spring that urges the plunger downwards, and that is capable of being compressed upwards, a spring compression mechanism unit having a rotating body that moves the plunger in a direction of compressing the spring based on the rotation of the first rotation output shaft of the motor in one direction, a reduction mechanism unit provided between the first rotation output shaft of the motor and the rotating body, having a first rotating input shaft that an output of the first rotation output shaft is transmitted to and a second rotation output shaft connected to the rotating body, that reduces the rotation speed of the first rotating input shaft for outputting to the second rotation output shaft, and a one-way clutch provided between the first rotation output shaft of the motor and the first rotating input shaft of the reduction mechanism unit, that permits rotation of the motor in said one direction that compresses the spring, and prohibits rotation of the motor in an opposite direction.
The reduction mechanism unit reduces the rotational speed of the rotating body to the rotational speed of the first rotation output shaft of the motor or less.
The one-way clutch is connected to the first rotation output shaft of the motor, and the first rotating input shaft of the reduction mechanism unit is connected to the first rotation output shaft of the motor.
The one-way clutch is connected to one end of the first rotation output shaft of the motor, and the first rotating input shaft of the reduction mechanism unit is connected to another end the first rotation output shaft of the motor.
The one-way clutch comprises an inner ring rotation unit connected to the first rotation output shaft of the motor, an outer periphery fixing unit provided at an outer periphery of the inner ring rotation unit, and an engaging member engaging between the inner ring rotation unit and the outer periphery fixing unit, that permits rotation of the inner ring rotation unit in one direction, and prohibits rotation in an opposite direction.
The one-way clutch may be a roller-type one-way clutch.
The one-way clutch may be a ratchet-type one-way clutch.
The allowable torque of the one-way clutch may be set to a range of 5.4 Nm or less.
According to the present invention, it is possible to set allowable torque of a one-way clutch to be small, and it is possible for a fastener driving tool to be both small and lightweight.
These objects and other objects and advantages of the present invention will become more apparent upon reading of the following detailed description and the accompanying drawings in which:
The following is an explanation with reference to the drawings of the embodiments to which the spring-driven type fastener driving tool of the present invention is applied. In all of the drawings illustrating the embodiments, portions having the same function are given the same numerals and are not repeatedly described. In the following explanation of the fastener driving tool of the present invention, for ease of explanation, the direction in which the fastener is driven is referred to as “downwards” and in the opposite direction to this direction is referred to as “upwards”. These expressions of direction are in no way limiting with regards to special embodiments or intentions. The same form expression is also possible when the direction in which the fastener is driven is the vertical direction on the present invention is not in any way limited whatever the direction of driving the fastener is.
The fastener driving tool 1 includes a fuselage housing unit 2, a handle housing unit 3, a battery pack (storage battery) 4, a nose (ejection section) 5, and a magazine 6. The handle housing unit 3 can be provided so as to branch off from the fuselage housing unit 2. The battery pack 4 is detachably installed at an end of the handle housing unit 3 and is electrically connected to an electric motor 7 (refer to
A plunger 8, a coil spring (compression spring) 9, the motor 7, a reduction mechanism unit 80 (refer to
As shown in
As shown in
A push switch 55 can be provided at the tip of the nose 5. The push switch 55 then detects that the tip of the nose 5 is substantially in contact with the member to be fastened. The push switch 55 also functions as an operation switch for controlling driving of the motor at the motor control circuit device 50 of the motor 7 with the trigger switch 10 and inputs a control signal that is off or on to the motor control circuit device 50 of the motor 7.
As shown in
As shown in
As shown in
As shown in
When it is intended to rotate the inner ring rotation unit 26 in the reverse rotation direction (anti-clockwise direction) B as shown in
This is to say that in cases where it is necessary to make the spring force (spring energy) large in order to drive in long or thick nails, it is necessary to make the contact surface area large in order to make the allowable torque large. In order to achieve this, measures can be adopted such as making the shaft length L (refer to
On the other hand, when it is intended to rotate the inner ring rotation unit 26 in the forward rotation direction (clockwise direction) A in
According to this embodiment, it is therefore possible to adopt a roller-type one-way clutch with a small allowable torque. The loss torque can therefore be made small by adopting a roller-type one-way clutch.
As shown in
The wire 16 is constructed by binding a plurality of metal wiring material so as to combine both flexibility and strength. The surface of the wire 16 is coated with resin so as to prevent wear at a drum groove 13b (trough) making contact with the wire 16. The outer peripheral section of the cylindrical section of the drum hook 22 is press-fitted into a center hole of the drum 13 and the drum hook 22 and the drum 13 are formed integrally. A bearing (for example, a ball bearing) 22b is press-fitted at an inner peripheral surface of the cylindrical section of the drum hook 22 and the bearing 22b is installed at the rotation output shaft 19. This means that the drum 13 and the drum hook 22 both become integral and are supported so as to be rotatable with respect to the rotation output shaft 19.
The power transmission pin 17 has a pin slide section (groove) 17a and a pin hooking section 17b. The pin slide section 17a engages with the pin support slide section 21a in the possession of the pin support plate 21 so as to be slidable. The pin hooking section 17b engages with a hook section 22a of the drum hook 22. The power transmission pin 17 is arranged so that its side end surface makes contact with a wall section within a guide channel 18a of the guide plate 18. The direction and extent of movement of the power transmission pin 17 is controlled by the plane shape of the guide channel 18a. The pin hooking section 17b that is the other end surface of the power transmission pin 17 is installed at the same height as the height of the hook section 22a in the axial direction of the rotation output shaft 19. When the power transmission pin 17 rotates in synchronization with the pin support plate 21, the pin hooking section 17b engages with the hook section 22a. The pin support plate 21 has a key groove 21b, with a key 20 provided at the rotation output shaft 19 engaging with the key groove 21b. The rotation output shaft 19, the pin support plate 21, and the power transmission pin 17 are therefore configured so as to always rotate in synchronization with each other.
As a result of the above configuration, the plunger 8 urged by the spring 9 is pushed upwards to a prescribed position on the upper dead point side (upper dead point position) as a result of the action of the motor 7, the reduction mechanism unit 80, and the spring compression mechanism unit 81, while resisting the urging force (firing power) of the spring 9. The spring 9 compressed to the prescribed upper dead point position by the spring compression mechanism unit 81 is then released. The urging force (firing force) obtained at the time of release then acts on the blade 8a fitted to the plunger 8 so as to provide an impact force from the blade 8a to the nail 23 loaded in the magazine 6. The nail 23 can therefore be driven in the direction of the member to be fastened from the nose 5. Next, the operation of driving in the nail 23 is explained together with the operation of the spring compression mechanism unit 81 with reference to
When the plunger 8 is in an initial state where the plunger 8 is stopped at the lower dead point (refer to
When an operator grasps the handle housing unit 3 of the fastener driving tool 1, pulls back the trigger switch 10, and presses the push switch (contact switch) 55 provided at the tip of the nose 5 against the member to be fastened, electrical power is supplied from the battery pack 4 to the motor 7 by the function of the motor control circuit device 50. The motor 7 (refer to
As shown in
A side end of the power transmission pin 17 comes into contact with a guide projection 18b that defines an inner wall section of a guide channel 18a in accordance with the pin support plate 21 being rotated from this state of being rotating through 135 degrees as shown in
For example, when the pin support plate 21 enters a state of rotation of approximately 270 degrees (
When the connection between the power transmission pin 17 and the hook section 22a is released in a state of rotation through approximately 270 degrees as shown in
When the drum 13 is rotated in reverse in the direction B by the force released from the compressed spring 9 so that the plunger 8 reaches the lower dead point, the blade 8a fitted to the end of the plunger 8 passes through the ejection section path 5a of the nose 5 and can therefore drive the nail 23 towards the member to be fastened. In this event, when the spring 9 is released and the plunger 8 reaches the lower dead point, a drum damper engaging section 13a of the drum 13 engages with a drum damper 13c shown in
When the drum 13 returns to the initial state, the drum damper engaging section 13a engages with the drum damper 13c fixed within the fuselage housing unit 2, and the drum 13 and the drum hook 22 are fixed in the initial position (reverse rotation stop position).
After the nail 23 is driven in, the power transmission pin 17 and the hook section 22a are re-engaged at the reverse rotation stop position of the drum 13, and the drum 13 again rotates forwards in the direction A so that the wire 16 is wound in. This means that the plunger 8 is pulled and the spring 9 is compressed again. The supply of electrical power from the battery pack 4 to the motor 7 by the circuit function of the motor control circuit device 50 is therefore stopped and rotation of the motor 7 is stopped.
It is preferable for the stopping of the motor 7 to take place after a prescribed time elapses from the detection of the time of driving by the motor stopping switch 56 (refer to
Energy of the rotational inertia of the rotor of the motor 7, the first pulley 14, the second pulley 15, the planetary gear unit 11, and the rotation output shaft 19 etc. is converted to energy for compressing the spring 9. However, as the rotational inertia energy approaches zero, when rotation of the drum 13 in the forward direction A falls to zero, on this occasion, the urging force of the spring 9 attempts to cause the drum 13 to rotate in the reverse rotation direction B and the rotor of the motor 7, the planetary gear unit 11, and the rotation output shaft 19 also attempt to rotate together with the drum 13.
When the released spring 9 then becomes extended to a certain extent, the reverse torque due to the urging force of the spring 9 becomes smaller than the loss torque of sliding sections and rotating axes etc. of the motor 7, the planetary gear unit 11, the rotation output shaft 19, and the plunger 8. The drum 13 therefore does not rotate in reverse. However, in a state where the plunger 8 is pushed up, and the spring 9 is compressed to a certain extent, the torque due to the urging force of the spring 9 is larger. This means that the drum 13 fitted to the rotation output shaft 19 rotates in reverse.
At this time, the reverse rotation prevention member such as the roller 28 of the one-way clutch 24 provided at one end of the rotation output shaft 7a of the motor 7 resists the reverse rotation force so as to engage with the fitting section 2b of the fuselage housing unit 2 via the outer ring fixing unit 25 of the one-way clutch 24. This means that reverse rotation of the rotor of the motor 7, the first pulley 14, the second pulley 15, the planetary gear unit 11, the rotation output shaft 19, and the drum 13 is prevented. When the plunger 8 is in a state of being pulled to a certain extent in resistance to the urging force of the spring 9, the plunger 8 is stopped at a position at a prescribed height from the lower dead point. It is therefore possible to obtain the following effects as a result of the installation of a one-way clutch in accordance with the present invention.
(1) According to the above embodiment, the one-way clutch 24 is installed between the rotation input shaft 15a of the reduction mechanism unit 80 and the rotation output shaft 7a of the motor 7. This means that it is possible to make the allowable torque in order to prevent reverse rotation of the drum 13 small. The structure of the one-way clutch 24 can also be made small and lightweight. Namely, the torque applied at the rotation output shaft 19 with the drum 13 in a stopped state is the product of the urging force of the spring 9 and a winding radius of the wire 16 of the drum 13, for example, 10 to 40 Nm. At this time, the torque (torque in the reverse rotation direction) occurring at the rotation output shaft 7a of the motor 7 is reduced by the pulley ratio of the first pulley 14 and the second pulley 15 and the reduction ratio of the planetary gear unit 11 and therefore becomes smaller than the torque of the rotation output shaft 19. It is therefore possible to make the allowable torque (torque preventing reverse rotation) of the one-way clutch 24 coupled to the rotation output shaft 7a of the motor 7 small. The reverse rotation prevention member constituting the one-way clutch 24 can therefore be made small, as can the whole of the one-way clutch 24. As described above, a reduction ratio at the reduction mechanism unit 80 is 150 to 300. The torque at the rotation output shaft 7a of the motor 7 at this time therefore becomes, for example, 0.033 to 0.27 Nm, which is extremely small compared to the torque of 10 to 40 Nm of the drum 13. However, it is preferable to put in place a safety factor of a maximum restricted torque used of 20 times in order to take into consideration the prevention of damage to the one-way clutch due to impact torque. For example, in the above embodiment, it is therefore preferable to use a one-way clutch having an allowable torque of up to 5.4 Nm that is 20 times the maximum restricted torque use of 0.27 Nm.
(2) It is possible for the stop position of the plunger 8 to be moved by 5 to 30 millimeters from the upper dead point by the one-way clutch 24. It is therefore possible to make the drive time from the start of operation activated by using a driving switch such as a trigger switch or a push switch etc. until driving short. As a result, it is possible to increase working efficiency, and it is possible to improve the so-called driving feeling by driving nails at the same time as operating the driving switch.
(3) It is possible to use a one-way clutch 24 with a small allowable torque. It is therefore possible to reduce loss torque of the one-way clutch 24 when the drum 13 is rotated in the forward rotation direction A. As a result, it is possible for inertial energy of the drum 13 after driving the nail 23 to continue to be used as compression energy of the spring 9 for driving the nails. It is therefore possible to achieve improved efficiency for the battery pack 4 and the number of nails that can be driven per one charging of the battery pack 4 can therefore be increased. In this event, and in particular, if a roller type of one-way clutch is used, it is possible to further reduce the loss when driving in the nails and the driving efficiency of the battery pack can therefore be further improved.
When the one-way clutch 24 is installed at the rotation output shaft 7a of the motor 7, the inner ring rotation unit 26 of the one-way clutch is connected to the rotation output shaft 7a of the motor 7. It is therefore possible to make the allowable rotational speed of the motor high and a high output can be obtained as a result.
(4) By installing the one-way clutch 24, when the plunger 8 is stopped, the tip of the blade 8a fitted to the plunger 8 can be positioned more closer to the side of the upper dead point than the head of the nail 23 loaded in the ejection section path 5a of the nose 5. If the rotation output shaft 19 then rotates in reverse more than is necessary, it is possible that the nail 23 will be pushed by the blade 8a so as to be ejected or released from the ejection section path 5a of the nose 5. It is therefore possible to stop the plunger 8 at a more appropriate position by installing the one-way clutch 24 and the unnecessary ejection or release of nails 23 can be prevented.
As becomes clear from the above description of the embodiment, according to the present invention, by providing a one-way clutch between an input side rotating shaft of a reduction mechanism unit and a rotation output shaft of a motor, it is possible to prevent reverse rotation of a rotating drum due to urging force in a downward direction of the spring using a one-way clutch with a small allowable torque. A stop position of the rotating drum can therefore be set to a desired position. It is therefore possible for the fastener driving tool to be made both small and lightweight, and for both working efficiency and driving feeling to be improved.
After the plunger 8 moves to the lower dead point, the power transmission pin 17 again engages with the plunger hook 8c and rotation of the motor 7 is stopped. In this case, because the one-way clutch 24 is provided, unnecessary reverse rotation of the motor 7 after stopping due to the urging force of the spring 9 can be prevented. The one-way clutch 24 is connected to one end (the lower end) of the rotation output shaft 7a of the motor 7. It is therefore possible to adopt a small one-way clutch, and the effects of the present invention can be obtained as with the embodiment shown above in
In the above embodiment, an explanation is given of the case where the one-way clutch 24 is a roller type clutch. However, the present invention can also use a ratchet type clutch as the one-way clutch.
Various embodiments and changes may be made thereunto without departing from the broad spirit and scope of the invention. The above-described embodiments are intended to illustrate the present invention, not to limit the scope of the present invention. The scope of the present invention is shown by the attached claims rather than the embodiments. Various modifications made within the meaning of an equivalent of the claims of the invention and within the claims are to be regarded to be in the scope of the present invention.
This application is based on Japanese Patent Application No. 2008-005465 filed on Jan. 15, 2008 and including specification, claims, drawings and summary. The disclosure of the above Japanese Patent Application is incorporated herein by reference in its entirety.
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