JPH0445820Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a head valve drive device for a nailing machine operated by air pressure.

(Prior Art) An example of the conventional art is Japanese Utility Model Application Publication No. 12576/1983.

(Problems to be solved by the invention) In the case of the nailing machine disclosed in the above publication, the fifth
As shown in the figure, the head valve v is pressurized based on the difference between the pressurizing area where the compressed air in the variable pressure chamber h pressurizes the head valve v and the pressurizing area where the compressed air in the pressurizing chamber k pressurizes the head valve v. Since the head valve v moves upward due to the pressure difference and operates by overcoming the negative pressurizing force, there are problems in that the operating speed of the head valve v is slowed down and it is necessary to form a pressurizing surface with a large area on the head valve v. As a result, there were problems such as an increase in storage space for the head valve drive mechanism and an increase in air consumption.

SUMMARY OF THE INVENTION An object of the present invention is to provide a head valve driving device for a nailing machine that can solve the above-mentioned problems, increase the operating speed of the head valve, and reduce the amount of air consumed for driving the air valve.

(Means for solving the problem) In the head valve driving device of the present invention, a piston that divides the inside of the cylinder into an upper cylinder chamber and a lower cylinder chamber is tightly fitted in a cylinder fixed in a housing so that it can slide up and down. In this type of nailing machine, near the upper end of the housing, there is provided an annular slide groove in which a variable pressure chamber is formed, which is communicated with a compressed air chamber via a trigger valve mechanism, and a ring-shaped slide groove is arranged below the slide groove. A head valve is installed near the upper end of the housing, the upper part of which is tightly fitted into a slide groove so as to be able to slide vertically and is biased upward by a spring, concentrically with the cylinder. The head valve has an intermediate seal surface that approaches and separates from the lower seal portion, a seal surface that has a diameter approximately equal to the diameter of the intermediate seal surface and circumscribes near the upper end of the cylinder, and a seal surface that connects the upper cylinder chamber to the outside air or the It has a configuration in which a valve hole communicating with the compressed air chamber and a pressure receiving surface that receives air pressure in the compressed air chamber when the intermediate seal surface moves below the lower seal portion are formed.

(Operation) When compressed air is sent into the variable pressure chamber in the slide groove in which the upper part of the head valve installed near the upper end of the housing is tightly fitted, the head valve is moved downward by the compressed air in the variable pressure chamber. When the intermediate seal surface of the head valve moves below the lower seal part of the housing, the upper cylinder chamber in the cylinder and the compressed air chamber are communicated with each other, and the pressure receiving surface of the head valve is exposed to the air pressure in the compressed air chamber. When pressed down, the head valve rapidly moves downward to the bottom dead center, and the piston is moved downward by the compressed air flowing into the upper cylinder chamber. When the piston moves down to the bottom dead center and the inside of the housing is in an equilibrium state, the head valve is moved up to the top dead center by the spring that urges the head valve upward, thereby communicating the upper cylinder chamber with the outside air. , the piston and lower cylinder move upward to top dead center due to the air pressure in the room.

(Example) Next, an example of the present invention will be described with reference to the drawings.

The housing 1 of the nailer main body H includes a cylinder storage part 2 in which a cylindrical cylinder 4 is vertically installed,
A grip portion 3 extending horizontally is formed on the rear side of the cylinder storage portion 2, and a driver guide 5 having a nail path for driving nails is attached to the lower end of the cylinder storage portion 2. A compressed air chamber 6 for supplying compressed air into the cylinder storage portion 2 is formed in the grip portion 3.

A piston 7 is tightly fitted into the cylinder 4 so as to be vertically slidable, and an upper cylinder chamber 8A and a lower cylinder chamber 8B are formed above and below the piston 7 inside the cylinder 4, and the piston 7
A driver 9 for driving a nail downward from the driver guide 5 is attached in a hanging manner at the center of the nail.

The top cap 10 is mounted on the upper end of the cylinder housing part 2, and a slide groove 10a which is open downward is formed in an annular shape in the upper part of the inner surface of the top cap 10, and a variable pressure chamber 11 is formed in the slide groove 10a.
An exhaust hole 12 is provided through a part of the recessed part 10b that is recessed in a circumferential manner on the inner surface near the center thereof,
Further, a slide groove 10 is provided below the concave portion 10b.
Upper seal part 1 having a sealing surface with the same diameter as the outer wall surface of a
3 and a lower seal part 14 having a seal surface whose diameter is larger than that of the upper seal part 13 are connected in a vertically stepped manner.

The head valve 15 is formed into a stepped cylindrical shape whose upper part is slightly smaller than the lower part, and the cylinder 4
It is urged upward by a spring 16 externally fitted on the upper part of the cylinder 4, and its upper end is tightly fitted into the slide groove 10a of the top cap 10 so that it can slide vertically, and its lower end is fitted near the upper end of the outer peripheral surface of the cylinder 4. The head valve 15 is tightly fitted in a vertically slidable manner, and is tightly fitted into the lower seal portion 14 of the top cap 10 when the head valve 15 moves upward slightly below the top dead center on the outer peripheral surface near the center of the head valve 15. Intermediate seal surface 1 disposed so as to separate from the lower seal part 14 during the downward movement of the head valve 15 to open and close the lower seal part 14.
7 is vertical and circumferentially formed. Furthermore, an upper pressure receiving surface 18A connected to the upper end of the intermediate sealing surface 17 is provided above and below the intermediate sealing surface 17 to receive air pressure that assists the downward movement of the head valve 15.
and a lower pressure receiving surface 18B arranged in parallel below the upper pressure receiving surface 18A to receive the air pressure that assists the upward movement of the head valve 15 are formed in a horizontal annular shape. Nearby, there is a hole that connects the upper cylinder chamber 8A and the compressed air chamber 6 during the downward movement of the head valve 15, and connects the upper cylinder chamber 8A and the exhaust hole 12 of the top cap 10 when the head valve 15 moves upward to the top dead center. A valve hole 19 for communication is provided therethrough. In order to reduce the pressure difference of the compressed air to the head valve 15, the diameter of the intermediate seal surface 17 of the head valve 15, that is, the diameter of the seal surface of the lower seal portion 14, and the seal surface 15b where the vicinity of the lower end of the head valve 15 is circumscribed. , that is, the diameter of the outer circumferential surface of the cylinder 4, is set to be approximately equal to the diameter of the outer circumferential surface of the cylinder 4.

A valve case 20 of the trigger valve mechanism T is attached to the lower end of the base end of the grip portion 3, and this valve case 20 has an inflow hole 20a provided at the lower end of the compressed air chamber 6, and an inflow hole 20a disposed at the lower end of the compressed air chamber 6. An outflow hole 20b provided below is provided through the outflow hole 20b.
b is a supply/discharge pipe 21 whose upper end communicates with the pressure transformation chamber 11;
is connected to the bottom edge of the

Valve stem 2 for opening and closing the inflow hole 20a
2 is tightly fitted into the valve case 20 so as to be vertically slidable with its lower end exposed, and is biased downward by a spring 24.

A trigger 25 provided opposite to the valve stem 22 for vertically operating the valve stem 22 is pivotably supported on the upper end of the safety lever 26 so as to be tiltable in the vertical direction. An idler 27 for pushing up is tiltably pinned, and when the trigger 25 is pulled up and the idler 27 pushes up the valve stem 22, the inflow hole 20a is opened and compressed air in the compressed air chamber 6 flows into the inflow hole. 20a, the outflow hole 20b, and the supply/discharge pipe 21 into the variable pressure chamber 11. Then, the head valve 15 is moved downward by the compressed air sent into the variable pressure chamber 11, and immediately after the start of this downward movement, the upper sealing surface 15a of the head valve 15 is attached to the upper seal portion 13.
After the exhaust hole 12 is closed by the head valve 15, the intermediate seal surface 17 is tightly fitted and the exhaust hole 12 is closed by the head valve 15.
The upper pressure receiving surface 18A is separated from the lower sealing portion 14, and the upper cylinder chamber 8A and the compressed air chamber 6 are communicated with each other, so that the upper pressure receiving surface 18A is separated from the compressed air chamber 6. The head valve 15 is pressurized downward by the compressed air flowing in from the variable pressure chamber 11 (see Fig. 2), and the head valve 15 is connected to the air pressure in the variable pressure chamber 11 and the upper pressure receiving surface 18.
The piston 7 moves downward rapidly as it is pushed down by the pressure combined with the air pressure that pressurizes the piston 7.
The nail is pressed downward by the compressed air flowing into A and moves downward together with the driver 9, and the nail is driven downward from the driver guide 5.

Further, the head valve 15 that has moved downward to the bottom dead center is inside the compressed air chamber 6, inside the variable pressure chamber 11, and in the upper cylinder chamber 8A.
Since the air pressure inside the supply/discharge pipe 21 is in an equilibrium state (see Fig. 3), even when the trigger 25 is pulled up, the spring 16 returns to a position slightly below the top dead center due to the elastic force of the spring 16. (See FIG. 4) In this state, the air remaining in the variable pressure chamber 11 is discharged from the supply/discharge pipe 21 to the outside air by the trigger release operation, and the head valve 15 returns to the top dead center. When the head valve 15 returns, the lower pressure receiving surface 18B is pressurized upward by the air pressure in the upper cylinder chamber 8A, and the head valve 15 is subjected to a combined force of the elastic force of the spring 16 and the air pressure applied to the lower pressure receiving surface 18B. The head valve 15 is moved upward by the pressure, and the return speed of the head valve 15 to the top dead center is accelerated, and the discharge of the compressed air in the upper cylinder 8A is accelerated. When the head valve 15 returns to the top dead center and the upper cylinder chamber 8A communicates with the outside air, the piston 7 moves from the return chamber 28 to the lower cylinder chamber 8B.
The compressed air flowing inside pressurizes it upward and moves it up to top dead center.

Next, the functions and effects of the embodiment having the above configuration will be explained.

In this example, in a nailing machine, a piston 7 is tightly fitted into a cylinder 4 fixed in a housing 1 so as to be able to slide vertically to partition the inside of the cylinder 4 into an upper cylinder chamber 8A and a lower cylinder chamber 8B. Near the upper end of 1, there is an annular slide groove 10a in which a variable pressure chamber 11, which is communicated with the compressed air chamber 6 via a trigger valve mechanism, is formed. 1
A lower seal part 14 having an inner diameter larger than the diameter of the outer circumferential surface of the housing 1 is formed, and the upper part is tightly fitted into the slide groove 10a near the upper end of the housing 1 so as to be vertically slidable, and the upper part is sealed upwardly by a spring 16. A head valve 15 which is biased toward the cylinder 4 is installed concentrically with the cylinder 4, and the head valve 15 has an intermediate seal surface 17 that approaches and separates from the lower seal portion 14, and a diameter that is approximately equal to the diameter of this intermediate seal surface 17. , a sealing surface 15b circumscribing near the upper end of the cylinder 4
, a valve hole 19 that unilaterally communicates the upper cylinder chamber 8A with the outside air or the compressed air chamber 6, and a valve hole 19 that unilaterally communicates the upper cylinder chamber 8A with the outside air or the compressed air chamber 6; A lower pressure receiving surface 18B is formed to receive the pressure.

Therefore, it is possible to speed up the downward movement speed of the head valve 15 so that the head valve 15 can be rapidly moved downward after the trigger operation, and the piston 7 and the driver 9 can also be rapidly moved downward. In addition to shortening the time, since the head valve 15 is assisted by the air pressure flowing from the compressed air chamber 6 and moves downward, fluctuations in the speed of the downward movement of the head valve 15 are reduced and the operating state of the head valve 15 is stabilized. This has the effect of suppressing variations in the nailing speed due to differences in the pulling angle of the trigger 25.

Furthermore, the returning speed of the head valve 15 to the top dead center can be increased to shorten the return time of the piston 7 and the driver 9.
This has the effect of significantly shortening the time required for each nailing operation.

In particular, the head valve 15 is provided with a negative pressure that prevents the operation of the head valve 15 when the head valve 15 is operated.
Since the air pressure that presses the head valve 15 in the counteracting direction based on the pressure area difference is not pressurized, the pressurizing area required to move the head valve 15 downward is reduced and the volume of the variable pressure chamber 11 is made as much as possible. This reduces the air consumption required for the downward movement of the head valve 15.
5 moves upward to near the top dead center by the elastic force of the spring 16, and the amount of air remaining in the variable pressure chamber 11 in this state becomes the air consumption required for the return of the head valve 15, which is necessary for the nail driving operation. This has the effect of significantly reducing air consumption.

Furthermore, the volume of the variable pressure chamber 11 is reduced to
Since the diameter of the outer wall surface of 1 can be shortened,
The shape of the top cap 10 can be made compact and the weight of the top cap 10 can be reduced.

Note that the elastic force of the spring 16 may be increased so that the head valve 15 is returned to the top dead center only by the elastic force of the spring 16.

(Effects of the invention) Since the present invention is configured as described above, it is possible to increase the downward movement speed of the head valve to increase the response speed when the piston starts downward movement, and also to increase the response speed when the piston starts downward movement. The supply state of compressed air into the upper cylinder chamber can be stabilized.

Furthermore, since the direction of movement of the piston is switched by moving the head valve, which has a length significantly shorter than the length of the cylinder, with the cylinder fixed, the driving force required to switch the direction of movement of the piston can be reduced. At the same time, the amount of air consumed to drive the head valve is only the amount of air discharged from the variable pressure chamber when the head valve moves upward, so the amount of air consumed to drive the head valve can be reduced. The drive mechanism can be made more compact.

In particular, since the diameter of the intermediate seal surface and the diameter of the seal surface circumscribing the cylinder are set to be approximately equal, the air pressure applied to the bottom of the head valve from both directions is approximately equal and cancels out. As a result, the pressure receiving area required to move the head valve downward can be reduced and the head valve can be made more compact.

[Brief explanation of the drawing]

Figures 1 to 4 show an embodiment of the present invention, with Figure 1 being a vertical sectional view of the main parts, Figures 2 and 3,
FIG. 4 is a vertical cross-sectional view of the main parts for explaining the operation of the head valve, and FIG. 5 is a vertical cross-sectional view showing the head valve mechanism of a conventional nail gun. DESCRIPTION OF SYMBOLS 1... Housing, 4... Cylinder, 6... Compressed air chamber, 10a... Slide groove, 11... Transformation chamber, 14... Lower seal portion, 15... Head valve, 17... Intermediate seal surface, 18A... ...Top pressure receiving surface, T...Trigger valve mechanism.

Claims (1)

[Scope of utility model registration request] In a nailer, a piston is tightly fitted in a cylinder fixed in a housing so as to be able to slide up and down, dividing the inside of the cylinder into an upper cylinder chamber and a lower cylinder chamber, and a trigger valve mechanism is installed near the upper end of the housing. An annular slide groove in which a variable pressure chamber is formed, which communicates with the compressed air chamber through the housing, and a lower seal portion disposed below the slide groove. A head valve whose upper portion is tightly fitted into the slide groove so as to be vertically slidable and is biased upward by a spring is installed concentrically with the cylinder, and the head valve has an intermediate seal surface that approaches and separates from the lower seal portion; a sealing surface having a diameter substantially equal to the diameter of the intermediate sealing surface and circumscribing the vicinity of the upper end of the cylinder; a valve hole that communicates the upper cylinder chamber with the outside air or the compressed air chamber; A head valve driving device comprising a pressure receiving surface that receives air pressure in the compressed air chamber when moving below the lower seal portion.