Patent Description:
There is known a driving tool referred to as a nailing machine in which a driving piston is actuated by a driving mechanism using a fluid such as compressed air as a power source, and in which a driver coupled to the driving piston is driven to drive a fastener such as a nail supplied to a nose. In such a nailing machine, the driving mechanism is actuated by operations of two members to drive a nail, which are one operation of pulling a trigger provided on a handle and another operation of pressing a contact arm, which protrudes at a tip end of the nose and is provided so as to be reciprocally movable, against an object.

In the following description, a state where the trigger is pulled by the one operation is referred to as "ON of the trigger", and a state where the one operation is released and the trigger is not pulled is referred to as "OFF of the trigger". In addition, a state where the contact arm is pressed by the other operation is referred to as "ON of the contact arm", and a state where the other operation is released and the contact arm is not pressed is referred to as "OFF of the contact arm".

In the nailing machine, for example, after the contact arm is set ON, the trigger is set ON with the contact arm being in the ON state, so that the driving mechanism is actuated to perform nail driving.

The trigger and the contact arm are set OFF after the nail driving, and the trigger and the contact arm are set ON again as described above, so that the driving mechanism is actuated to perform a next nail driving. An operation in which the trigger and the contact arm are set ON for each nail driving after being set OFF to perform the next nail driving as described is referred to as "a single driving mode".

In contrast, there has been proposed a technique in which the contact arm is set OFF after the nail driving with the trigger being in an ON state, and the contact arm is set ON again with the trigger being in the ON state, so that the driving mechanism is actuated to perform the next nail driving. An operation in which continuous nail driving is performed by repeating ON and OFF of the contact arm with the trigger being in the ON state as described is referred to as "a continuous driving mode".

In the continuous driving mode, the nail driving can be continuously performed each time the contact arm is pressed against the object after a nail driving with the trigger being pulled, and thus it is suitable for quick work. On the other hand, in the single driving mode, the operations of the trigger and the contact arm are released after a nail driving, and the trigger is pulled again after the contact arm is pressed against the object so as to perform the next nail driving; it is not suitable for quick work although an effect of regulating undesired operation is presented. Therefore, there has been proposed a technique in which, a continuous nail driving operation for a certain period of time is made possible only by the operation of pressing the contact arm against the object, with the operation of the trigger not released after a first nail driving is performed by pressing the contact arm against the object and then pulling the trigger (see, for example, Patent Literature <NUM>).

<CIT>, <CIT>, and <CIT> relate to various examples of fluid dampers.

In a configuration in which continuous driving of nails or the like can be performed only by the operation of pressing the contact arm against the object without releasing the operation of the trigger, control that enables the continuous driving operation for a certain period of time is performed using an electric timer, so that clocking can be stably performed. However, a nailing machine driven by compressed air does not include a supply source of electricity. Therefore, in order to use an electric timer, a power supply and a circuit are required.

Alternatively, a configuration is conceivable in which a mechanical clocking mechanism is incorporated into the trigger. However, it is necessary to incorporate the mechanical clocking mechanism in a limited space, and it is difficult to stably perform clocking. If the clocking cannot be performed stably, a period of time during which the continuous driving operation is possible is not constant, and the operation feeling gets worse.

It is conceivable to use various types of dampers, such as an oil damper, as the mechanical clocking mechanism. The oil damper is a configuration of applying a load to movement of the piston by resistance of oil, in which if the piston is moved by a force of a spring, time required for the movement can be used for clocking, by reducing a moving speed of the piston with the force of the spring and keeping the moving speed of the piston constant.

In such an oil damper, the spring expands and contracts in accordance with a position of the piston, and a force corresponding to an expansion and contraction amount is applied to the piston. Therefore, in a state where the force applied to the piston by the spring is weak and a force exceeding the viscous resistance of the oil is not applied to the piston, the piston cannot be moved at a constant speed. In a driving tool to which such an oil damper is applied as a clocking mechanism, it is difficult to stably perform the clocking, and the period of time during which the continuous driving operation is possible is not constant.

On the other hand, it is conceivable to prevent a change in the force applied to the piston by using a long spring with respect to a stroke of the piston, but when the length of the spring is increased, a size of the oil damper increases. Further, the driving tool to which such an oil damper is applied as a clocking mechanism is also increased in size.

The present invention has been made to solve these problems, and an object thereof is to provide a fluid damper that is capable of controlling the moving speed of the piston appropriately in accordance with the change in the force applied to the piston by the spring, and a driving tool that is capable of stably switching between presence and absence of performing of the continuous driving operation by the operation of the contact arm, with a mechanical configuration using the fluid damper.

In order to solve the problems described above, the present invention provides a driving tool according to the independent claim.

In the present invention, the force applied to the piston by the biasing member changes in accordance with the position of the piston. By changing the resistance of the fluid at the time the piston moves in accordance with the change of the force applied to the piston by the biasing member, a load suitable for the force applied to the piston by the spring can be provided to the piston.

The driving tool includes a driving mechanism which is configured to drive a fastener supplied to a nose portion and which is configured to switch between presence and absence of actuation of the driving mechanism by using the fluid damper described above.

The present invention provides a driving tool including: a driving mechanism which is configured to drive a fastener supplied to a nose portion, a trigger which is configured to receive one operation for actuating the driving mechanism, a contact arm which is provided so as to be reciprocally movable and which is configured to receive another operation for actuating the driving mechanism, a contact lever which is provided so as to be capable of being actuated by operations of the trigger and the contact arm and which is configured to switch between presence and absence of actuation of the driving mechanism, and a fluid damper which is configured to control a moving speed of the contact lever, in which the fluid damper includes a cylinder tube portion which is filled with a fluid, a piston which is provided so as to be movable in an inner portion of the cylinder tube portion and whose moving speed is controlled with resistance of the fluid, and a biasing member which is configured to expand and contract in accordance with a position of the piston and which is configured to apply a force corresponding to an expansion and contraction amount to the piston, and the resistance of the fluid at time the piston moves is changed in accordance with the position of the piston.

In the fluid damper of the present invention, the force applied to the piston by the biasing member changes in accordance with the position of the piston. By changing the resistance of the fluid at the time the piston moves in accordance with the change of the force applied to the piston by the biasing member, a load suitable for the force applied to the piston by the biasing member can be provided to the piston. Accordingly, the moving speed of the moving member can be appropriately controlled with the load applied due to the resistance of the fluid, with a configuration of moving the moving member by the force of the biasing member.

In the fluid damper of the present invention, since a load suitable for the force applied to the piston by the biasing member can be provided to the piston, influence of the force applied to the piston by the biasing member can be eliminated, and the moving speed of the piston can be appropriately controlled.

In the driving tool of the present invention, since the fluid damper described above is provided, it is possible to stably perform the clocking with a mechanical clocking mechanism, and it is possible to switch between the presence and absence of the actuation of the driving mechanism at a predetermined timing.

Hereinafter, embodiments of an oil damper, which is an example of a fluid damper of the present invention, and a nailing machine, which is an example of a driving tool of the present invention, will be described with reference to the drawings.

<FIG> is a main part configuration diagram illustrating an example of a nailing machine according to a first embodiment. <FIG> is an overall configuration diagram illustrating the example of the nailing machine of the first embodiment.

A nailing machine 1A according to the first embodiment includes a driving cylinder <NUM> that is actuated with compressed air serving as a fluid, which is a power source, to perform a striking operation, and an air chamber <NUM> in which compressed air supplied from an external air compressor (not illustrated) is stored. In the nailing machine 1A, the driving cylinder <NUM> is provided in an inner portion of a housing <NUM> having a shape extending in one direction, and the air chamber <NUM> is provided in an inner portion of a handle <NUM> extending from the housing <NUM> in another direction. In addition, in the nailing machine 1A, a blowback chamber <NUM> is provided around a lower portion of the driving cylinder <NUM> at the inner portion of the housing <NUM>.

The driving cylinder <NUM>, which is an example of a driving mechanism, includes a driver <NUM> drives a nail or the like (not illustrated), and a driving piston <NUM> provided with the driver <NUM>. The driving piston <NUM> is slidably provided. In the driving cylinder <NUM>, the driving piston <NUM> is moved by being pushed with compressed air to drive the driver <NUM>.

The compressed air is supplied to the air chamber <NUM> from a compressed air source such as an air compressor through an air plug <NUM> provided at an end portion of the handle <NUM>. The blowback chamber <NUM> is supplied with compressed air to drive and return the driving piston <NUM> after a driving operation to an initial position.

The nailing machine 1A includes, at one end portion of the housing <NUM>, a nose <NUM> into which the driver <NUM> enters, and a magazine <NUM> that supplies a nail (not illustrated) to the nose <NUM>. The nose <NUM> extends along a moving direction of the driver <NUM>. In consideration of a use form of the nailing machine 1A, a side at which the nose <NUM> is provided is referred to as a lower direction.

The nailing machine 1A includes a main valve <NUM> that regulates inflow and outflow of compressed air in the air chamber <NUM> to cause the driving piston <NUM> to reciprocate, and a actuating valve <NUM> that actuates the main valve <NUM>. The main valve <NUM> switches between inflow of compressed air from the air chamber <NUM> into the driving cylinder <NUM> and discharge of the compressed air from inside the driving cylinder <NUM> to an outside, so that the driving piston <NUM> is caused to reciprocate. The actuating valve <NUM> includes a valve stem <NUM> that is provided so as to be reciprocally movable, and the valve stem <NUM> is moved by a predetermined amount to open a flow path <NUM> to actuate the main valve <NUM>.

The nailing machine 1A includes a trigger <NUM> that receives one operation for actuating the actuating valve <NUM>, a contact arm <NUM> that moves in response to another operation to be pressed against an object to which a nail is hit, and a contact lever <NUM>. The contact lever <NUM> is provided so as to be capable of being actuated by an operation of the trigger <NUM> having received the one operation and by an operation of the contact arm <NUM> having received the other operation, and switches between presence and absence of actuation of the actuating valve <NUM>. Further, the nailing machine 1A includes a regulating part <NUM> that regulates movement, a moving speed, or a movement amount of the contact lever <NUM> for a predetermined period of time, and that switches between presence and absence of actuation of the contact lever <NUM> depending on the contact arm <NUM>, according to presence or absence of engagement between the contact lever <NUM> and the contact arm <NUM> in this example.

The trigger <NUM> is provided on one side of the handle <NUM> which is a side where the nose <NUM> is provided. One end portion side of the trigger <NUM>, which is a side close to the housing <NUM>, is rotatably supported by a shaft <NUM>. Further, a side opposite the side supported by the shaft <NUM>, that is, the other end portion side of the trigger <NUM> which is a side far from the housing <NUM>, is biased by a spring <NUM> in a direction of moving toward a side where the nose <NUM> is provided, by a rotation operation using the shaft <NUM> as a fulcrum.

In this example, a moving range of the trigger <NUM> by the rotation operation using the shaft <NUM> as a fulcrum is regulated by bringing the trigger <NUM> abutting against an abutting portion formed in the housing <NUM> and the handle <NUM>.

The contact lever <NUM> includes, at one end portion thereof, an engaging portion <NUM> with which the contact arm <NUM> can engage, and the other end portion thereof is rotatably supported by a shaft <NUM> on the trigger <NUM>. A pushing portion <NUM> capable of pushing the valve stem <NUM> of the actuating valve <NUM> is provided between the engaging portion <NUM> and the shaft <NUM>. Further, a side opposite the side supported by the shaft <NUM>, that is, the one end portion side of the contact lever <NUM> where the engaging portion <NUM> is provided, is biased by a spring <NUM> such as a torsion coil spring in a direction of moving toward a side where the nose <NUM> is provided, by a rotation operation using the shaft <NUM> as a fulcrum.

The contact arm <NUM> is provided so as to be movable along an extension direction of the nose <NUM>, and includes an abutting portion <NUM> that abuts against an object at a tip end side of the nose <NUM>. In addition, the contact arm <NUM> includes a first pushing portion <NUM> that actuates the contact lever <NUM>, and a second pushing portion <NUM> that actuates the regulating part <NUM>. The contact arm <NUM> is biased by a spring <NUM> in a direction of protruding from the tip end side of the nose <NUM>.

In a state where an operation is released, the trigger <NUM> is biased by the spring <NUM> to move to an initial position thereof by the rotation operation using the shaft <NUM> as a fulcrum. The trigger <NUM> is moved, by the rotation operation using the shaft <NUM> as a fulcrum according to a pulling operation, from the initial position to an operating position thereof where the actuating valve <NUM> can be actuated by the contact lever <NUM>.

When pushed by the contact arm <NUM>, the contact lever <NUM> is moved, by the rotation operation using the shaft <NUM> as a fulcrum, from an initial position thereof to a position where the driving cylinder <NUM> can be actuated in accordance with the position of the trigger <NUM>, that is, to an actuation possible position in this example where the valve stem <NUM> can be pushed to actuate the actuating valve <NUM>.

When the abutting portion <NUM> is pushed by being abutted against the object, the contact arm <NUM> moves from an initial position thereof to an actuating position thereof where the contact lever <NUM> is actuated by the first pushing portion <NUM> and the regulating part <NUM> is actuated by the second pushing portion <NUM>.

When the first pushing portion <NUM> engages with the engaging portion <NUM> of the contact lever <NUM> by an operation of moving the contact arm <NUM> from the initial position thereof to the actuating position thereof, the contact lever <NUM> is actuated by the operation of the contact arm <NUM>, and the contact lever <NUM> is moved from the initial position thereof to the actuation possible position thereof. In addition, with respect to the contact arm <NUM>, the presence or absence of engagement between the engaging portion <NUM> of the contact lever <NUM> and the first pushing portion <NUM> of the contact arm <NUM> is switched in accordance with the position of the trigger <NUM> and the position of the contact lever <NUM>.

That is, when the trigger <NUM> is operated, the contact lever <NUM> moves together with the trigger <NUM> by the rotation operation of the trigger <NUM> using the shaft <NUM> as a fulcrum. Accordingly, the initial position and the actuation possible position of the contact lever <NUM> are relative positions that change in accordance with the position of the trigger <NUM>, and the positions of the engaging portion <NUM> and the pushing portion <NUM> of the contact lever <NUM> vary depending on whether the trigger <NUM> is in the initial position thereof or the operating position thereof.

In a state where the trigger <NUM> and the contact lever <NUM> are moved to respective initial positions, the pushing portion <NUM> of the contact lever <NUM> does not contact the valve stem <NUM> of the actuating valve <NUM>. In addition, in a state where the contact lever <NUM> is moved to the initial position thereof, the pushing portion <NUM> of the contact lever <NUM> does not contact the valve stem <NUM> of the actuating valve <NUM> even if the trigger <NUM> moves to the operating position thereof.

In contrast, when the contact arm <NUM> moves to the actuating position thereof in a state where the trigger <NUM> is moved to the initial position thereof, the first pushing portion <NUM> of the contact arm <NUM> engages with the engaging portion <NUM> of the contact lever <NUM>, and the contact lever <NUM> moves to the actuation possible position thereof. Accordingly, when the trigger <NUM> moves to the operating position thereof, the pushing portion <NUM> of the contact lever <NUM> can push the valve stem <NUM> of the actuating valve <NUM>, and the actuating valve <NUM> can be actuated by the contact lever <NUM>.

On the other hand, when the trigger <NUM> moves to the operating position thereof in a state where the contact arm <NUM> is moved to the initial position thereof, the first pushing portion <NUM> cannot engage with the engaging portion <NUM> of the contact lever <NUM> even if the contact arm <NUM> moves, and the pushing portion <NUM> of the contact lever <NUM> cannot push the valve stem <NUM> of the actuating valve <NUM> even if the trigger <NUM> moves to the operating position thereof.

Accordingly, even if the trigger <NUM> is operated first and the contact arm <NUM> is operated next, the actuating valve <NUM> cannot be actuated, and continuous driving by an operation of pushing the contact arm <NUM> against an object cannot be performed. In the present embodiment, since the regulating part <NUM> is provided, when the contact arm <NUM> is operated first and the trigger <NUM> is operated next, the continuous driving can be performed with the presence or absence of the operation of the contact arm <NUM> for a predetermined period of time.

The regulating part <NUM> includes a regulating member <NUM> that regulates a position of the contact lever <NUM> to an actuation standby position where the contact lever <NUM> can be actuated by the contact arm <NUM>. In addition, the regulating part <NUM> includes an oil damper <NUM> that maintains a state for a predetermined period of time where the contact lever <NUM> is in the actuation standby position.

The actuation standby position of the contact lever <NUM> is a position or a range where the contact lever <NUM> can engage with the contact arm <NUM>, and the contact lever <NUM> can be actuated by the contact arm <NUM> while the contact lever <NUM> is in this position or range. In the following description, the actuation standby position is referred to as an engagement possible position.

The regulating member <NUM> is provided so as to be movable along a moving direction of the contact arm <NUM>, and includes, at one end portion along the moving direction, a pushing portion 90a that pushes the contact lever <NUM>. The regulating member <NUM> is provided with the pushing portion 90a thereof adjacent to the first pushing portion <NUM> of the contact arm <NUM>. In addition, the regulating member <NUM> includes an engaged portion 90b that can engage with the oil damper <NUM>.

The regulating member <NUM> is biased by a spring 90c in a direction in which the pushing portion 90a approaches the contact lever <NUM>.

Further, the regulating member <NUM> moves from an initial position thereof where the pushing portion 90a does not contact the contact lever <NUM> to a return regulating position for regulating the position of the contact lever <NUM> to an engagement possible position where the contact lever <NUM> and the contact arm <NUM> can engage with each other. The return regulating position of the regulating member <NUM> is a position where, by an operation of that the regulating member <NUM> moves by being pushed by the spring 90c, the pushing portion 90a protrudes relative to the first pushing portion <NUM> and the pushing portion 90a can contact the engaging portion <NUM> of the contact lever <NUM> in a state where the contact arm <NUM> is moved to the initial position thereof.

The oil damper <NUM> includes a moving member <NUM> that moves the regulating member <NUM>, and controls movement, a moving speed, or a movement amount of the moving member <NUM>. In this example, the oil damper <NUM> controls the moving speed of the moving member <NUM>. The moving member <NUM> is provided so as to be movable along a moving direction of the regulating member <NUM>, and includes a pushed portion 92a that is pushed by the second pushing portion <NUM> of the contact arm <NUM> and an engaging portion 92b that engages with the engaged portion 90b of the regulating member <NUM>.

The oil damper <NUM> is provided with the pushed portion 92a of the moving member <NUM> in a moving path of the second pushing portion <NUM> of the contact arm <NUM> that moves from the initial position thereof to the actuating position thereof. The moving member <NUM> moves from an initial position thereof where the regulating member <NUM> is moved to the initial position thereof, to a clocking starting position for starting measuring a time period during which the movement of the contact lever <NUM> moved to the engagement possible position thereof after an operation of the contact arm <NUM> is released is regulated, that is, a time period until the regulating member <NUM>, which is moved to the return regulating position, moving to the initial position thereof in this example.

The regulating member <NUM> is provided with the engaged portion 90b in a moving path of the engaging portion 92b which is formed due to the movement of the moving member <NUM>. By an operation of moving the moving member <NUM> of the oil damper <NUM> from the initial position thereof to the clocking starting position thereof, the engagement between the engaging portion 92b of the moving member <NUM> and the engaged portion 90b of the regulating member <NUM> is released. Accordingly, the regulating member <NUM> is pushed by the spring 90c to move from the initial position thereof to the return regulating position thereof.

In addition, by an operation of moving the moving member <NUM> of the oil damper <NUM> from the clocking starting position thereof to the initial position thereof, the engaging portion 92b of the moving member <NUM> and the engaged portion 90b of the regulating member <NUM> engage with each other. Accordingly, the regulating member <NUM> moves from the return regulating position thereof to the initial position thereof.

<FIG> is a cross-sectional view of the oil damper according to the first embodiment. The oil damper <NUM> of the first embodiment includes a cylinder tube portion 93a that is filled with oil, a piston 93b that is provided so as to be movable in an inner portion of the cylinder tube portion 93a and whose moving speed is controlled with resistance due to viscosity or the like of oil, and a piston shaft portion 93c that transmits movement of the piston 93b to the moving member <NUM>.

The cylinder tube portion 93a is provided with a space that is defined in a substantially cylindrical shape and that is filled with oil. The piston 93b has a circular shape conforming to a shape of an inner circumferential surface of the cylinder tube portion 93a, and a hole portion 93d through which the oil passes is provided so as to penetrate both sides of the piston 93b. In this example, a plurality of hole portions 93d are provided along a circumferential direction of the piston 93b. One end portion of the piston shaft portion 93c is attached to the piston 93b, and the other end portion thereof protruding from the cylinder tube portion 93a is coupled to the moving member <NUM>.

The oil damper <NUM> includes a check valve 93e that switches a load in accordance with a direction, in which the piston 93b moves, by opening and closing the hole portions 93d in accordance with the direction in which the piston 93b moves. The check valve 93e is provided on one surface of the piston 93b which is a side where the piston shaft portion 93c protrudes in the piston 93b, and has a shape capable of blocking the hole portions 93d. The check valve 93e is movable in a direction of separating from the piston 93b along the moving direction of the piston 93b, and is biased by a valve opening and closing spring 93f in a direction to be pushed against the piston 93b.

In an operation of moving the piston 93b in a direction in which the moving member <NUM> moves from the initial position thereof toward the clocking starting position thereof, the oil flows from the other surface toward the one surface side of the piston 93b. Accordingly, the check valve 93e is pushed by the oil passing through the hole portions 93d, so that the check valve 93e is separated from the one surface of the piston 93b while compressing the valve opening and closing spring 93f and the hole portions 93d are opened.

In contrast, in an operation of moving the piston 93b in a direction in which the moving member <NUM> moves from the clocking starting position thereof toward the initial position thereof, the oil flows from the one surface toward the other surface side of the piston 93b. Accordingly, the check valve 93e is pushed against the piston 93b by being pushed by the valve opening and closing spring 93f and the oil, and the hole portions 93d are closed by the check valve 93e.

As described, by opening and closing the hole portions 93d of the piston 93b with the check valve 93e, area of a flow path through which the oil flows when the piston 93b moves is changed. When the hole portions 93d are opened, the area of the flow path through which the oil flows when the piston 93b moves is increased, and resistance at the time the oil flows decreases. In contrast, when the hole portions 93d are closed, the area of the flow path through which the oil flows when the piston 93b moves is reduced, and the resistance at the time the oil flows increases.

The oil damper <NUM> includes a spring <NUM> that expands and contracts in accordance with a position of the piston 93b and that applies a force corresponding to an expansion and contraction amount to the piston 93b. The spring <NUM> is an example of a biasing member, is configured with a coil spring, and is provided between a spring retainer <NUM> provided in the inner portion of the cylinder tube portion 93a and the other surface of the piston 93b.

In a state where the moving member <NUM> is moved to the initial position thereof, the spring <NUM> is compressed by a predetermined amount and biases the piston 93b in a direction in which the piston shaft portion 93c protrudes from the cylinder tube portion 93a. The direction in which the piston shaft portion 93c protrudes from the cylinder tube portion 93a is a direction in which the moving member <NUM> moves from the clocking starting position thereof toward the initial position thereof.

In the operation of moving the piston 93b in the direction in which the moving member <NUM> moves from the initial position thereof toward the clocking starting position thereof, the spring <NUM> is compressed between the spring retainer <NUM> and the piston 93b. With a force to extend of the compressed spring <NUM>, the piston 93b is pushed in the direction in which the moving member <NUM> moves from the clocking starting position thereof toward the initial position thereof.

The oil damper <NUM> includes a first bypass flow path 93ii and a second bypass flow path 93i<NUM> that reduce the load at the time the piston 93b moves. The first bypass flow path 93ii is an example of a flow path expanded portion, and is provided to face a position of the piston 93b that is in a state where the moving member <NUM> is moved to the vicinity of the initial position thereof, which is a terminal position of a movement range of the piston 93b that is moved by a force applied by the spring <NUM>. The first bypass flow path 93ii is formed by providing a recess on the inner circumferential surface of the cylinder tube portion 93a. In the cylinder tube portion 93a, an inner diameter thereof at a portion where the first bypass flow path 93ii is provided is larger than an inner diameter thereof at a portion where the first bypass flow path 93ii is not provided.

Accordingly, in a state where the piston 93b faces the first bypass flow path 93ii, a gap between an outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion 93a is increased, as compared with a case where the piston 93b faces the inner circumferential surface of the cylinder tube portion 93a at a portion where the first bypass flow path 93ii is not provided.

Therefore, when the moving member <NUM> moves between the initial position thereof and the clocking starting position and the piston 93b moves to a position that is not facing the first bypass flow path 93ii, the area of the flow path through which the oil flows when the piston 93b moves is reduced. Therefore, in an operation of moving the piston 93b, the resistance at the time the oil flows between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion 93a increases, and the load applied when the piston 93b moves increases.

In contrast, when the piston 93b is moved to a position facing the first bypass flow path 93ii by moving the moving member <NUM> to the vicinity of the initial position thereof, the area of the flow path through which the oil flows when the piston 93b moves is increased. Therefore, in an operation of moving the piston 93b, the resistance at the time the oil flows between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion 93a is reduced, and the load applied when the piston 93b moves is reduced.

The second bypass flow path 93i<NUM> is an example of a flow path expanded portion, and is provided to face a position of the piston 93b that is in a state where the moving member <NUM> is moved to the vicinity of the clocking starting position thereof. The second bypass flow path 93i<NUM> is formed by providing a recess on the inner circumferential surface of the cylinder tube portion 93a. In the cylinder tube portion 93a, an inner diameter thereof at a portion where the second bypass flow path 93i<NUM> is provided is larger than an inner diameter thereof at a portion where the second bypass flow path 93i<NUM> is not provided.

Accordingly, in a state where the piston 93b faces the second bypass flow path 93i<NUM>, a gap between an outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion 93a is widened, as compared with a case where the piston 93b faces the inner circumferential surface of the cylinder tube portion 93a at a portion where the second bypass flow path 93i<NUM> is not provided.

Therefore, when the piston 93b is moved to a position facing the second bypass flow path 93i<NUM> by moving the moving member <NUM> to the vicinity of the clocking starting position thereof, the area of the flow path through which the oil passes when the piston 93b moves is increased. Therefore, in the operation of moving the piston 93b, the resistance at the time the oil flows between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion 93a is reduced, and the load applied when the piston 93b moves is reduced.

The oil damper <NUM> includes a diaphragm 93j that keeps a volume in the cylinder tube portion 93a substantially constant regardless of the position of the piston 93b. The diaphragm 93j is configured with an elastically deformable member and is provided on the other end portion side of the cylinder tube portion 93a.

In the oil damper <NUM>, since a length of the piston shaft portion 93c protruding into the cylinder tube portion 93a changes in accordance with the position of the piston 93b, a volume of the piston shaft portion 93c and the volume in the cylinder tube portion 93a change. Accordingly, by deforming the diaphragm 93j in accordance with the length of the piston shaft portion 93c protruding into the cylinder tube portion 93a, the volume in the cylinder tube portion 93a is kept substantially constant, and the oil is prevented from being compressed.

In the oil damper <NUM> configured as described above, the moving member <NUM> moves from the clocking starting position thereof to the initial position thereof by the force to extend of the spring <NUM>, and the moving speed of the moving member <NUM> is controlled with the load applied when the piston 93b moves in the cylinder tube portion 93a due to the viscosity of the oil. In addition, when the moving member <NUM> moves to the vicinity of the initial position thereof by the force to extend of the spring <NUM>, the piston 93b moves to the position facing the first bypass flow path 93ii, the resistance at the time the oil flows between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion 93a is reduced, and the load applied to the piston 93b when the moving member <NUM> moves toward the initial position thereof is reduced.

Accordingly, a time period during which the moving member <NUM> moves from the clocking starting position thereof to the initial position thereof is controlled, and a time period during which the regulating member <NUM> moves from the return regulating position thereof to the initial position thereof is controlled. Therefore, with respect to the contact lever <NUM> having moved to the engagement possible position thereof by an operation of moving the contact arm <NUM> toward the initial position thereof, a time period until returning to the initial position thereof is controlled by operations of the regulating member <NUM> and the moving member <NUM>.

<FIG> are illustrative diagrams illustrating examples of operations of the nailing machine according to the first embodiment, and <FIG> are illustrative diagrams illustrating examples of operations of the oil damper according to the first embodiment. The operations of the nailing machine 1A according to the first embodiment will be described below with reference to the drawings.

In an initial state, as illustrated in <FIG>, the trigger <NUM> is not pulled and is in the initial position thereof, and the contact arm <NUM> is not pressed against the object and is in the initial position thereof. Therefore, the contact lever <NUM>, the regulating member <NUM>, and the moving member <NUM> are also in respective initial positions.

In an initial state where the trigger <NUM> is in the initial position thereof and the contact lever <NUM> is in the initial position thereof, the engaging portion <NUM> of the contact lever <NUM> is positioned in a moving path of the first pushing portion <NUM> of the contact arm <NUM>.

When the contact arm <NUM> moves from the initial position thereof to the actuating position thereof by being pressed against the object, starting from the initial state illustrated in <FIG>, the first pushing portion <NUM> of the contact arm <NUM> pushes the engaging portion <NUM> of the contact lever <NUM> as illustrated in <FIG>. Accordingly, by the rotation operation using the shaft <NUM> as a fulcrum, the contact lever <NUM> moves from the initial position thereof to the actuation possible position thereof where the valve stem <NUM> of the actuating valve <NUM> can be pushed to actuate the actuating valve <NUM>. Not that even if the contact lever <NUM> moves to the actuation possible position thereof, the valve stem <NUM> cannot be pushed by the contact lever <NUM> unless the trigger <NUM> moves to the operating position thereof.

When the contact arm <NUM> moves to the actuating position thereof, the second pushing portion <NUM> of the contact arm <NUM> pushes the pushed portion 92a of the moving member <NUM> of the oil damper <NUM>. Accordingly, the moving member <NUM> of the oil damper <NUM> moves from the initial position thereof to the clocking starting position thereof.

Further, when the moving member <NUM> moves to the clocking starting position thereof, the engagement between the engaging portion 92b of the moving member <NUM> and the engaged portion 90b of the regulating member <NUM> is released, and the regulating member <NUM> is pushed by the spring 90c to move from the initial position thereof to the return regulating position thereof.

In addition, when the moving member <NUM> is moved to the initial position thereof, the piston 93b faces the first bypass flow path 93ii in the oil damper <NUM>, as illustrated in <FIG>. Accordingly, while the moving member <NUM> is positioned in the vicinity of the initial position thereof in the operation of moving the piston 93b in the direction in which the moving member <NUM> moves from the initial position thereof toward the clocking starting position thereof as indicated by an arrow U, the resistance at the time the oil flows as indicated by an arrow O<NUM> between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion 93a is reduced and the load applied when the piston 93b moves is reduced.

Further, in the operation that the piston 93b moves in the direction in which the moving member <NUM> moves from the initial position thereof to the clocking starting position thereof, the oil flows from the other surface to the one surface side of the piston 93b.

Accordingly, the check valve 93e is pushed by the oil passing through the hole portions 93d, so that the check valve 93e is separated from the one surface of the piston 93b while compressing the valve opening and closing spring 93f and the hole portions 93d are opened.

When the piston 93b passes past the position facing the first bypass flow path 93ii as illustrated in <FIG> in the operation of moving the moving member <NUM> from the initial position thereof to the clocking starting position thereof, the gap between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion 93a is narrowed. On the other hand, when the hole portions 93d of the piston 93b are opened, the oil flows from the other surface, through the hole portions 93d, to the one surface side of the piston 93b as indicated by an arrow O<NUM>. Accordingly, the load applied when the piston 93b moves is reduced.

Since the piston 93b is pushed by the contact arm <NUM> via the moving member <NUM>, an operating load of the contact arm <NUM> is reduced when the load applied at the time the piston 93b moves is reduced.

In addition, when the moving member <NUM> moves to the vicinity of the clocking starting position thereof, the piston 93b faces the second bypass flow path 93i<NUM> as illustrated in <FIG>. Accordingly, in the operation of moving the piston 93b in the direction in which the moving member <NUM> moves from the initial position thereof to the clocking starting position thereof, the resistance at the time the oil flows between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion 93a is reduced and the load applied when the piston 93b moves is reduced.

In a state where the moving member <NUM> is moved to the vicinity of the clocking starting position thereof, a compression amount of the spring <NUM> is increased, and a reaction force thereof to return the piston 93b is increased. In this state, since the load applied when the piston 93b moves is reduced, the operating load of the contact arm <NUM> is reduced.

When the moving member <NUM> moves to the vicinity of the clocking starting position and stops, the check valve 93e is pushed against the piston 93b by being pushed by the valve opening and closing spring 93f, and the hole portions 93d are blocked by the check valve 93e.

When the trigger <NUM> is pulled to be moved from the initial position thereof to the operating position thereof after the contact arm <NUM> moves to the actuating position thereof by being pressed against the object from the initial state, as illustrated in <FIG>, the pushing portion <NUM> of the contact lever <NUM> in the actuation possible position thereof pushes the valve stem <NUM> of the actuating valve <NUM>. Accordingly, the main valve <NUM> is controlled to actuate the driving cylinder <NUM> with compressed air, the driving piston <NUM> moves in a direction in which a fastener (not illustrated), which is a nail in this example, is driven, and a driving operation of the nail (not illustrated) is performed with the driver <NUM>. In addition, a part of the air in the driving cylinder <NUM> is supplied to the blowback chamber <NUM>. After the driving operation, the compressed air is supplied from the blowback chamber <NUM> to the driving cylinder <NUM>, and the driving piston <NUM> moves in a direction in which the driver <NUM> is returned.

While the trigger <NUM> is at the operating position and in a pulled state after the driving operation, the contact arm <NUM> moves from the actuating position thereof to the initial position thereof by the force of the spring <NUM> as illustrated in <FIG>, by releasing a force of pressing the contact arm <NUM>.

When the contact arm <NUM> moves to the initial position thereof, the pushing against the contact lever <NUM> by the first pushing portion <NUM> is released, and the contact lever <NUM> starts moving in a direction of returning from the actuation possible position thereof toward the initial position thereof by the rotation operation using the shaft <NUM> as a fulcrum by a force of the spring <NUM>.

The regulating member <NUM> that is moved to the return regulating position regulates the movement of the contact lever <NUM> that moves in the direction of returning from the actuation possible position thereof toward the initial position thereof, with the pushing portion 90a positioned on a movement path of the contact lever <NUM>.

Accordingly, when the contact arm <NUM> moves to the initial position thereof, the contact lever <NUM> moves to come into contact with the pushing portion 90a of the regulating member <NUM> and stops at the engagement possible position thereof. Further, the contact lever <NUM> having moved to the engagement possible position thereof has the engaging portion <NUM> thereof positioned on a movement path of the first pushing portion <NUM> of the contact arm <NUM>.

In addition, when the contact arm <NUM> moves to the initial position thereof, the pushing against the moving member <NUM> of the oil damper <NUM> by the second pushing portion <NUM> of the contact arm <NUM> is released, so that, in the oil damper <NUM>, the piston 93b is pushed by the force to extend of the compressed spring <NUM> as illustrated in <FIG> and the moving member <NUM> starts moving in a direction of returning from the clocking starting position thereof toward the initial position thereof as indicated by an arrow D.

In the operation of moving the piston 93b in the direction in which the moving member <NUM> moves from the clocking starting position thereof to the initial position thereof, the oil flows from the one surface to the other surface side of the piston 93b. Accordingly, the check valve 93e is pushed against the piston 93b due to being pushed by the valve opening and closing spring 93f and the oil, and the state where the hole portions 93d are blocked by the check valve 93e is maintained.

In addition, when the piston 93b passes past the position facing the second bypass flow path 93i<NUM> in the operation of moving the moving member <NUM> from the clocking starting position thereof to the initial position thereof, the gap between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion 93a is narrowed.

Accordingly, in the operation of moving the piston 93b in the direction in which the moving member <NUM> moves from the clocking starting position thereof toward the initial position thereof, the oil cannot pass through the hole portions 93d of the piston 93b, the resistance at the time the oil flows between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion 93a is increased, and the load applied when the piston 93b moves is increased. Therefore, the moving speed of the piston 93b moved by the force to extend of the spring <NUM> is reduced, and becomes a constant one corresponding to magnitude of the load.

As described, the moving member <NUM> moves from the clocking starting position thereof toward the initial position thereof by the force of the spring <NUM>, but the moving speed of the moving member <NUM> is controlled by the oil damper <NUM>. Accordingly, the time period during which the moving member <NUM> moves from the clocking starting position thereof toward the initial position thereof is controlled, and while the engaging portion 92b of the moving member <NUM> and the engaged portion 90b of the regulating member <NUM> are in an unengaged state, the regulating member <NUM> stops at the return regulating position thereof as illustrated in <FIG>.

Therefore, the engaging portion <NUM> is positioned on the movement path of the first pushing portion <NUM> of the contact arm <NUM> during a predetermined period of time in which the moving member <NUM> moves from the clocking starting position thereof to the initial position thereof, that is, during a period of time in which the engaging portion 92b of the moving member <NUM> and the engaged portion 90b of the regulating member <NUM> are in an unengaged state.

Accordingly, when the contact arm <NUM> having moved to the initial position thereof moves from the initial position thereof to the actuating position thereof again by being pressed against the object before the predetermined period of time in which the moving member <NUM> moves from the clocking starting position thereof to the initial position thereof elapses, with the trigger <NUM> being in the operating position thereof and in a pulled state, the first pushing portion <NUM> of the contact arm <NUM> can push the engaging portion <NUM> of the contact lever <NUM>.

Therefore, when the contact arm <NUM> having moved to the initial position thereof is moved to the actuating position thereof again within the predetermined period of time, with the trigger <NUM> being in the operating position thereof and in a pulled state, the engaging portion <NUM> of the contact lever <NUM> is pushed by the first pushing portion <NUM> of the contact arm <NUM>, the contact lever <NUM> moves to the actuation possible position thereof, and the pushing portion <NUM> pushes the valve stem <NUM> of the actuating valve <NUM>, as illustrated in <FIG>.

Therefore, a continuous driving operation can be performed by an operation of pressing the contact arm <NUM> against the object during the predetermined period time, with the trigger <NUM> being in the operating position thereof and in a pulled state.

In contrast, when the predetermined period of time elapses since the contact arm <NUM> moves to the initial position thereof, with the trigger <NUM> being in the operating position thereof and in a pulled state, the moving member <NUM> moves to the initial position thereof due to the oil damper <NUM>.

When the moving member <NUM> moves to the vicinity of the initial position thereof, the piston 93b faces the first bypass flow path 93ii as illustrated in <FIG>. Accordingly, as indicated by the arrow D, in the operation of moving the piston 93b in the direction in which the moving member <NUM> moves from the clocking starting position thereof toward the initial position thereof, the resistance at the time the oil flows as indicated by an arrow O<NUM> between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion 93a is reduced and the load applied when the piston 93b moves is reduced.

In a state where the moving member <NUM> is moved to the vicinity of the initial position thereof, the compression amount of the spring <NUM> is reduced, and the reaction force to return the piston 93b is reduced. In this state, since the load applied when the piston 93b moves is reduced, the moving member <NUM> can be reliably moved to the initial position thereof by the force to extend of the spring <NUM>.

When the moving member <NUM> moves to the initial position thereof, as illustrated in <FIG>, the engaging portion 92b of the moving member <NUM> and the engaged portion 90b of the regulating member <NUM> are engaged. Accordingly, the regulating member <NUM> moves from the return regulating position thereof to the initial position thereof by being pressed by the moving member <NUM> that is moved by the oil damper <NUM>.

When the regulating member <NUM> moves to the initial position thereof, the contact lever <NUM> moves from the engagement possible position to the initial position thereof, by the rotation operation using the shaft <NUM> as a fulcrum by the spring <NUM>, in a case where the trigger <NUM> is in the operating position thereof. When the contact lever <NUM> moves to the initial position thereof with the trigger <NUM> in the operating position thereof, the engaging portion <NUM> of the contact lever <NUM> is retracted from the moving path of the first pushing portion <NUM> of the contact arm <NUM>.

Accordingly, when the predetermined period of time elapses since the contact arm <NUM> moves to the initial position thereof, with the trigger <NUM> being in the operating position thereof and in a pulled state, even when the contact arm <NUM> moves to the actuating position thereof by the operation of pressing the contact arm <NUM> against the object, the first pushing portion <NUM> of the contact arm <NUM> does not contact the engaging portion <NUM> of the contact lever <NUM> and the contact lever <NUM> is not pushed, as illustrated in <FIG>.

Therefore, the actuating valve <NUM> is not pushed by the contact lever <NUM>, and the driving operation is not performed. Therefore, the continuous driving operation by pressing the contact arm <NUM> against the object, with the trigger <NUM> being in the operating position thereof and in a pulled state, can be regulated by lapse of time using a mechanical configuration.

As described above, when the predetermined period of time elapses since the driving operation completes, the contact lever <NUM> moves to the initial position thereof. After the contact lever <NUM> moves to the initial position thereof, the contact arm <NUM> is moved to the initial position thereof by releasing the force of pressing the contact arm <NUM>. In addition, the trigger <NUM> moves to the initial position thereof by releasing the force of pulling the trigger <NUM>. Accordingly, the initial state as illustrated in <FIG> is recovered. In the initial state, the engaging portion <NUM> of the contact lever <NUM> moves to the moving path of the first pushing portion <NUM> of the contact arm <NUM>.

Accordingly, when the trigger <NUM> moves to the operating position there by being pulled as illustrated in <FIG> after the contact arm <NUM> moves to the actuating position thereof by the operation of being pressed against the object as illustrated in <FIG>, the valve stem <NUM> of the actuating valve <NUM> is pushed by the contact lever <NUM> that is moved to the actuation possible position thereof, and the driving operation is performed.

When the trigger <NUM> moves to the operating position thereof by being pulled before the contact arm <NUM> is pressed against the object from the initial state illustrated in <FIG>, the engaging portion <NUM> of the contact lever <NUM> is retracted from the moving path of the first pushing portion <NUM> of the contact arm <NUM>.

Accordingly, after the trigger <NUM> is in the operating position thereof and in a pulled state from the initial state, the first pushing portion <NUM> of the contact arm <NUM> does not contact the engaging portion <NUM> of the contact lever <NUM> and the contact lever <NUM> is not pushed, even when the contact arm <NUM> moves to the actuating position thereof by the operation of being pressed against the object.

Therefore, the valve stem <NUM> of the actuating valve <NUM> is not pushed by the contact lever <NUM>, and the driving operation is not performed. Therefore, it is possible to regulate a driving operation that is by an operation other than an operation of a normal procedure of pressing the contact arm <NUM> against the object before pulling the trigger <NUM>.

The oil damper <NUM> is provided to reduce the moving speed of the moving member <NUM> in the operation of moving from the clocking starting position thereof to the initial position thereof, and provides the load applied when the piston 93b moves with the viscosity of the oil. On the other hand, in the operation of moving the moving member <NUM> from the initial position thereof toward the clocking starting position thereof by pressing the contact arm <NUM> against the object, the viscosity of the oil acts as a load applied when the piston 93b moves, and the operating load of the contact arm <NUM> increases.

Therefore, the oil damper <NUM> is provided with the check valve 93e on the piston 93b. The hole portions 93d of the piston 93b are opened when the piston 93b moves in a direction in the operation of pressing the contact arm <NUM> against the object, thereby reducing the load applied when the piston 93b moves. Accordingly, the operating load of the contact arm <NUM> is reduced. In addition, when the piston 93b moves in a direction in the operation of moving the moving member <NUM> from the clocking starting position thereof to the initial position thereof, the hole portions 93d of the piston 93b are closed by the check valve 93e, so that the load required when the piston 93b moves can be applied.

Further, since the oil damper <NUM> is provided with the first bypass flow path 93ii, when the moving member <NUM> moves to the vicinity of the initial position thereof in the operation of moving the piston 93b in the direction in which the moving member <NUM> moves from the clocking starting position thereof toward the initial position thereof, the resistance at the time the oil flows between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion 93a is reduced and the load applied when the piston 93b moves is reduced.

When the load applied when the piston 93b moves is large in a state where the compression amount of the spring <NUM> is reduced and where the force to return the piston 93b is reduced, the force to return the piston 93b is small, there is a possibility that the moving member <NUM> cannot be moved to the initial position during the predetermined period of time. In such a case, a continuous driving operation may be possible by the operation of pressing the contact arm <NUM> against the object even if the predetermined period of time elapses, with the trigger <NUM> being in the operating position thereof and in a pulled state.

In contrast, in the state where the compression amount of the spring <NUM> is reduced and the force to return the piston 93b is reduced, the moving member <NUM> can be reliably moved to the initial position thereof during the predetermined period of time by the force to extend of the spring <NUM> since the load applied when the piston 93b moves is reduced. Therefore, it is possible to reliably control a period of time, during which the continuous driving operation can be performed, by the operation of pressing the contact arm <NUM> against the object with the trigger <NUM> being in the operating position thereof and in a pulled state.

Further, when the force applied to the piston 93b by the spring <NUM> is reduced by providing the first bypass flow path 93ii in accordance with a position of the piston 93b where the load is desired to be reduced, the resistance of the oil at the time the piston 93b moves can be reduced, and a configuration can be easily implemented in which the resistance of the oil at the time the piston 93b moves is changed in accordance with a change in the force applied to the piston 93b by the spring <NUM>.

Since the oil damper <NUM> is provided with the second bypass flow path 93i<NUM>, when the moving member <NUM> moves to the vicinity of the clocking starting position thereof in the operation of moving the piston 93b in the direction in which the moving member <NUM> moves from the initial position thereof toward the clocking starting position thereof, the resistance at the time the oil flows between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion 93a is reduced and the load applied when the piston 93b moves is reduced.

In a state where the compression amount of the spring <NUM> is increased and the reaction force to return the piston 93b is increased, the operating load of the contact arm <NUM> is reduced since the load applied when the piston 93b moves is reduced. Here, the second bypass flow path 93i<NUM> may not be provided.

<FIG> is a cross-sectional view illustrating an oil damper according to a second embodiment. The oil damper <NUM> of the second embodiment includes a cylinder tube portion <NUM> that is filled with oil, the piston 93b that is provided so as to be movable in an inner portion of the cylinder tube portion <NUM> and whose moving speed is controlled with viscosity of the oil, and the piston shaft portion 93c that transmits movement of the piston 93b to the moving member <NUM>.

The cylinder tube portion <NUM> is provided with a space that is defined in a substantially cylindrical shape and that is filled with oil. The piston 93b has a circular shape conforming to a shape of an inner circumferential surface of the cylinder tube portion <NUM>, and a plurality of hole portions 93d through which the oil passes are provided so as to penetrate both sides of the piston 93b. One end portion of the piston shaft portion 93c is attached to the piston 93b, and the other end portion thereof protruding from the cylinder tube portion 93a is coupled to the moving member <NUM>.

The oil damper <NUM> includes the check valve 93e that switches a load in accordance with a direction, in which the piston 93b moves, by opening and closing the hole portions 93d in accordance with the direction in which the piston 93b moves. The check valve 93e is movable in a direction of separating from the piston 93b along the moving direction of the piston 93b, and is biased by the valve opening and closing spring 93f in a direction to be pushed against the piston 93b.

In an operation of moving the piston 93b in a direction in which the moving member <NUM> moves from an initial position thereof to a clocking starting position thereof, the check valve 93e is pushed by the oil passing through the hole portions 93d, so that the check valve 93e is separated from one surface of the piston 93b while compressing the valve opening and closing spring 93f and the hole portions 93d are opened.

In contrast, in an operation of moving the piston 93b in a direction in which the moving member <NUM> moves from the clocking starting position thereof to the initial position thereof, the check valve 93e is pushed against the piston 93b by being pushed by the valve opening and closing spring 93f and the oil, and the hole portions 93d are blocked by the check valve 93e.

The oil damper <NUM> includes the spring <NUM> that presses the piston 93b. The spring <NUM> is an example of a biasing member, is configured with a coil spring, and is provided between the spring retainer <NUM> provided in the inner portion of the cylinder tube portion <NUM> and the other surface of the piston 93b.

The oil damper <NUM> includes a bypass flow path <NUM> that reduces a load applied when the piston 93b moves. The bypass flow path <NUM> is an example of a flow path expanded portion, and is provided to face a position of the piston 93b that is in a state where the moving member <NUM> is moved to the vicinity of the initial position thereof, which is a terminal position of a movement range of the piston 93b that is moved by a force applied by the spring <NUM>. The inner circumferential surface of the cylinder tube portion <NUM> is in a tapered shape such that an inner diameter gradually increases toward a portion facing the piston 93b in a state where the moving member <NUM> is moved to the vicinity of the initial position thereof, and an inner diameter of a portion where the bypass flow path <NUM> is provided is larger than an inner diameter of a portion where the bypass flow path <NUM> is not provided.

Accordingly, in the operation of moving the moving member <NUM> from the clocking starting position thereof toward the initial position thereof, a gap between an outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion <NUM> gradually widens, and area of a flow path through which the oil flows when the piston 93b moves gradually increases.

Therefore, when the piston 93b moves to the position facing the bypass flow path <NUM> by moving the moving member <NUM> to the vicinity of the initial position thereof, resistance at the time the oil flows between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion <NUM> is reduced and a load applied when the piston 93b moves is reduced, in the operation of moving the piston 93b.

The oil damper <NUM> includes a diaphragm 93j that keeps a volume in the cylinder tube portion <NUM> substantially constant regardless of the position of the piston 93b. The diaphragm 93j is configured with an elastically deformable member and is provided on the other end portion side of the cylinder tube portion <NUM>.

In the oil damper <NUM> configured as described above, the moving member <NUM> moves from the clocking starting position thereof to the initial position thereof by a force to extend of the spring <NUM>, and a moving speed of the moving member <NUM> is controlled with the load applied when the piston 93b moves in the cylinder tube portion <NUM> due to the viscosity of the oil. In addition, when the moving member <NUM> moves to the vicinity of the initial position thereof by the force to extend of the spring <NUM>, the piston 93b moves to the position facing the bypass flow path <NUM>, the resistance at the time the oil flows between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion <NUM> is reduced, and the load applied to the piston 93b when the moving member <NUM> moves toward the initial position thereof is reduced.

<FIG> are illustrative diagrams illustrating examples of operations of the oil damper according to the second embodiment, and among operations of the nailing machine 1A, the operations of the oil damper according to the second embodiment will be described.

When the moving member <NUM> is moved to the initial position thereof as illustrated in <FIG>, the piston 93b faces the bypass flow path <NUM> in the oil damper <NUM> as illustrated in <FIG>. Accordingly, while the moving member <NUM> is positioned in the vicinity of the initial position thereof in the operation of moving the piston 93b in the direction in which the moving member <NUM> moves from the initial position thereof toward the clocking starting position thereof as indicated by an arrow U, the resistance at the time the oil flows as indicated by an arrow O<NUM> between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion <NUM> is reduced and the load applied when the piston 93b moves is reduced.

Further, in the operation of moving the piston 93b moves in the direction in which the moving member <NUM> moves from the initial position thereof toward the clocking starting position thereof, the oil flows from the other surface to the one surface side of the piston 93b.

In the operation of moving the moving member <NUM> from the initial position thereof to the clocking starting position thereof, the gap between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion <NUM> gradually narrows as illustrated in <FIG>. On the other hand, when the hole portions 93d of the piston 93b open, the oil flows from the other surface, through the hole portions 93d, to the one surface side of the piston 93b as indicated by an arrow O<NUM>. Accordingly, the load applied when the piston 93b moves is reduced.

When the moving member <NUM> moves to the vicinity of the clocking starting position thereof and stops, the check valve 93e is pushed against the piston 93b by being pushed by the valve opening and closing spring 93f and the hole portions 93d are blocked by the check valve 93e, as illustrated in <FIG>.

When the contact arm <NUM> moves to the initial position thereof by releasing a force of pressing the contact arm <NUM> after a driving operation, the pushing against the moving member <NUM> of the oil damper <NUM> by the second pushing portion <NUM> of the contact arm <NUM> is released, so that, in the oil damper <NUM>, the piston 93b is pushed by the force to extend of the compressed spring <NUM> as illustrated in <FIG> and the moving member <NUM> starts moving in a direction of returning from the clocking starting position thereof toward the initial position thereof as indicated by an arrow D.

Accordingly, in the operation of moving the piston 93b in the direction in which the moving member <NUM> moves from the clocking starting position thereof toward the initial position thereof, the oil cannot pass through the hole portions 93d of the piston 93b, the resistance at the time the oil flows between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion <NUM> is increased, and the load applied when the piston 93b moves is increased. Therefore, the moving speed of the piston 93b moved by the extending force of the spring <NUM> is reduced, and becomes a constant one corresponding to magnitude of the load.

When the moving member <NUM> moves to the vicinity of the initial position thereof, the piston 93b faces the bypass flow path <NUM> as illustrated in <FIG> Accordingly, as indicated by the arrow D, in the operation of moving the piston 93b in the direction in which the moving member <NUM> moves from the clocking starting position thereof toward the initial position thereof, the resistance at the time the oil flows as indicated by an arrow O<NUM> between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion <NUM> is reduced and the load applied when the piston 93b moves is reduced.

In a state where the moving member <NUM> is moved to the vicinity of the initial position thereof, a compression amount of the spring <NUM> is reduced, and a force to return the piston 93b is reduced. In this state, since the load applied when the piston 93b moves is reduced, the moving member <NUM> can be reliably moved to the initial position thereof by the force to extend of the spring <NUM>. In addition, since the area of the flow path through which the oil flows when the piston 93b moves gradually increases in the operation of moving the moving member <NUM> from the clocking starting position thereof to the initial position thereof, it is possible to prevent an abrupt increase or decrease in resistance when the oil flows.

In the embodiments described above, it is disclosed that the area of the flow path through which the oil passes when the piston 93b moves changes. At the time of performing the clocking, since the hole portions 93d are blocked and do not function as a flow path, this "change in area of the flow path" can be rephrased as "change in cross-sectional area" between the outer circumferential surface of the piston 93b and the inner circumferential surface of the cylinder tube portion 93a.

In the embodiments described above, oil dampers using the resistance due to the viscosity of oil are described as examples of the fluid damper of the present invention, and the present invention is not limited thereto. The present invention is applicable to various types of cylinder dampers, for example, a damper obtained by filling and enclosing a liquid different from oil in a cylinder, a damper obtained by filling and enclosing a gas such as nitrogen gas in a cylinder instead of oil, or a damper having a configuration of controlling inflow of gas into a cylinder and outflow of the gas from inside the cylinder.

In the embodiments described above, a nailing machine that drives a nail is described as an example of the driving tool of the present invention, and the present invention is not limited thereto. The present invention is also applicable to, for example, a screw driving machine that drives a screw.

Claim 1:
A driving tool comprising:
a driving mechanism (<NUM>) which drives a fastener supplied to a nose portion;
a trigger (<NUM>) which receives one operation for actuating the driving mechanism (<NUM>);
a contact arm (<NUM>) which is provided so as to be reciprocally movable and which receives another operation for actuating the driving mechanism (<NUM>);
a contact lever (<NUM>) which is provided so as to be capable of being actuated by operations of the trigger and the contact arm (<NUM>) and which is configured to switch between presence and absence of actuation of the driving mechanism (<NUM>);
characterized in that
a fluid damper which is configured to control a moving speed of the contact lever (<NUM>), wherein
the fluid damper comprises:
a cylinder tube portion (93a, <NUM>) which is filled with a fluid;
a piston (93b) which is provided so as to be movable in an inner portion of the cylinder tube portion (93a, <NUM>) and whose moving speed is controlled with resistance of the fluid; and
a biasing member (<NUM>) which expands and contracts in accordance with a position of the piston (93b) and which applies a force corresponding to an expansion and contraction amount of the biasing member (<NUM>) to the piston (93b), wherein
the resistance of the fluid at a time the piston (93b) moves is changed in accordance with the position of the piston (93b).