JPS5824231B2 - internal combustion tools - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention operates a main piston in a main cylinder built into a tool body by the combustion pressure of a mixed gas, thereby rapidly moving a driver as an impact member connected to the piston. This invention relates to an internal combustion type tool, such as an internal combustion type automatic nailer, which is capable of performing nail driving work by driving the nails one by one from within a nose protruding from the tool body.

For example, a combustion chamber is filled with a mixture of flammable gas such as LPG and air, and the high combustion gas pressure obtained by igniting and burning this mixture is applied to the upper chamber of the piston in the cylinder, causing the piston to move. When trying to obtain working power by driving, it is necessary to install a fluid circuit related to fuel supply to supply pressurized air and LPG into the combustion chamber at a low cost and at an appropriate ratio, and to increase combustion efficiency. A fluid control circuit for applying combustion pressure to the piston, a fluid control circuit for scavenging and exhausting residual combustion gas, and a fluid control circuit for controlling the supply of fuel, ignition and combustion, introduction to the upper chamber of the piston, and reciprocation of the piston. -Various circuits such as a fluid control circuit are required to automatically and continuously perform strokes such as piston return and combustion chamber cleaning/exhaust in sequence, and these circuit configurations are not compatible with other various types of tools. It constitutes the tool body together with the structural members and is incorporated into the housing.

Therefore, the complicated configuration of these circuits inevitably leads to a complicated structure of the tool itself.

Further, in order to improve workability, it is necessary that one working stroke of the tool be carried out in a short time.

In addition, it is also necessary to minimize the consumption of pressurized air, which is used to create an air-fuel mixture and as a means of transmitting various signals, in order to perform highly economical operations.

The present invention has been proposed in view of these various circumstances.

That is, an object of the present invention is to simplify the circuit configuration in an internal combustion engine, improve cycle performance, and reduce the consumption of air and the like.

Another object of the present invention is to simplify the structure of the tool so that it can be easily manufactured and processed, and also to reduce the weight of the tool as a whole, and to make the tool smaller. It is.

Therefore, in order to achieve the above object, the present invention unifies the opening and closing of the scavenging air conduit and the blowback air (i.e. piston return air) conduit, which were conventionally performed by two independent valves. This can be done automatically and at efficient timing using two valves.

A main cylinder, a main piston slidably and tightly fitted into the main cylinder, a driver integrally connected to the main piston, a combustion chamber, and an opening/closing operation between the combustion chamber and the piston upper chamber of the cylinder. a head valve that communicates with a lower piston chamber of the cylinder; a blowback chamber that selectively disconnects or conducts between the combustion chamber and the air chamber; and selectively disconnects or conducts between the air chamber and the blowback chamber. Scavenging to
a return air cut valve; an exhaust valve that selectively blocks or connects the combustion chamber and the exhaust port opening to the atmosphere; a first position that connects the upper chamber of the head valve to the air chamber; and the air chamber. It has a second position that conducts between the scavenging/return air cut valve and the exhaust valve, and takes the above-mentioned first position during normal times, and switches to the second position in response to combustion chamber pressure during combustion. and a timing chamber in which air for return driving of the release valve is stored via the scavenging/return cut valve, and the scavenging/air cut valve has first and second openings communicating with the air chamber. A third opening communicating with the blowback chamber, a fourth opening communicating with the combustion chamber, and fifth and sixth openings communicating with the timing chamber are opened in the peripheral wall, and the opening is connected to the air chamber via a release valve at one end. Seventh selectively communicated
A main valve stem consisting of a large diameter part and a small diameter part is slidably and tightly fitted into the cylinder, and an opening is provided at one end of the main valve stem. A sub-valve cylinder is bored into the sub-valve cylinder, and a sub-valve stem consisting of a large diameter part and a small diameter part is slidably and tightly fitted into this sub-valve cylinder, and a constricted part is provided in the middle of the sub-valve stem. A through-axial hole is bored through the valve stem, and each of the valve stems is normally located toward one end, and is located between the air chamber and the blowback chamber, between the air chamber and the combustion chamber, and between the air chamber and the combustion chamber. When air pressure is introduced from the seventh opening, both the main valve stem and the sub-valve stem are switched to the other end side, and the timing chamber is in the first position in which the connection with the timing chamber is cut off. A second position is adopted in which the air chamber and the blowback chamber, the combustion chamber, and the timing chamber are in a conductive state, and the air pressure acting on the upper surface of the large diameter portion of the sub-valve stem through the inside of the above-mentioned through-axis direction causes the above-mentioned From the second position, only the sub-valve stem is switched in one end direction to take a third position in which only the third opening communicating with the blowback chamber is blocked from the first and second openings, and the seventh When the supply of air to the opening is cut off, it returns to the first position, and the conduction air pressure at the second position of the scavenging/return air cut valve is applied to the release valve via the timing chamber. The release valve in the second position is switched to the first position by switching the release valve from the second position to the first position.

Next, an embodiment of the present invention shown in the drawings will be described.

Note that FIG. 1 is a schematic cross-sectional view of a tool to which the present invention is applied, and FIGS. 2 and 3 are schematic cross-sectional views of main parts sequentially explaining various operating states according to strokes.

In each of these figures, 1 is a housing forming a tool body.

2 is a main cylinder, into which a main piston 3 is slidably and tightly fitted.

This piston 3 has a driver 4 as a nail driving impact member.
are connected.

The driver 4 faces from the tip 4a side into a nose 5, which is a nail ejecting part, which is protruded from the main body, and is capable of powerfully hitting nails (not shown) that are supplied and loaded one by one into the nose 5 in advance. There is.

Reference numeral 6 denotes a bumper, which is disposed at the lower end of the cylinder 2 and serves as a lower seat at the bottom dead center of the main piston 3.

A combustion chamber 7 is formed above and outside the main cylinder 2, and has a spark plug 8 as an ignition means.

This plug 8 can ignite within the combustion chamber 7 by actuating the piezoelectric element 9 using an operating member such as a trigger (not shown).

Reference numeral 10 denotes a head valve, which is slidably and tightly fitted into the head valve cylinder 11 so as to enable communication or isolation between the piston upper chamber of the main cylinder 2 and the combustion chamber 7.

Reference numeral 12 denotes a blowback chamber, which communicates with the lower piston chamber of the main cylinder 2 through a port 13 .

14 is an air chamber, which is communicated with an air source 15 such as a compressor.

16 is an LPG source such as a cylinder.

17 is a fuel supply valve, which connects the air chamber 14 and LP.
It is interposed between the G source 16, the combustion chamber I, a needle valve 18 and an exhaust valve 1□9, which will be described later.

That is, in this fuel supply valve 17, a valve stem is slidably and tightly fitted into a valve cylinder.

Further, the valve stem has an operating projection projecting outward from the main body at the upper end in the figure.

Note that the needle valve 18 has a knob 18a protruding outward from the housing 1 so that the amount of throttling can be adjusted from the outside.

Further, the exhaust valve 19 is interposed between the combustion chamber 7 and an opening 20 to the atmosphere, and is constructed by fitting a valve stem slidably tightly into a valve cylinder.

Reference numeral 21 denotes a scavenging/return air cut valve, which is interposed between the air chamber 14, the combustion chamber 7, and a timing chamber 22, which will be described later, and the details of its construction will be explained below in FIG. 2.

That is, as is clear from these figures, the valve cylinder 211 of the scavenging/return air cut valve 21 has a large diameter portion 211a at the left end in the figure and a small diameter portion 211b at the remaining right end in the figure. A first opening 212 communicating with the blowback chamber 12 and second and third openings 21 communicating with the air chamber 14 are provided in the peripheral wall of the narrow diameter portion 211b.
3° 214 and a fourth communicating with the timing chamber 22.
A fifth opening 215, 216 and a sixth opening 217 communicating with the combustion chamber 7 are opened.

Note that among the above-mentioned openings, the fifth opening 216 communicating with the timing chamber 22 has an orifice 216a interposed therein.

Further, a seventh opening 218 to the atmosphere is provided at one end of the cylinder 211, and a release valve 218 is provided at the other end.
4, which selectively communicates with the air chamber 14 via the eighth
An opening 219 is opened.

A main valve stem 220 is slidably and tightly fitted into the cylinder 211.

This main valve stem 220 has a thick shaft portion 220a that is loosely fitted into the large diameter portion 211a of the cylinder 211 on the left end side in the drawing, and the remaining right end portion in the drawing is attached to the cylinder 211. The thin shaft portion 220b is slidably and tightly fitted into the thin diameter portion 211b of the thin shaft portion 220b.

On the outer periphery of the thin shaft portion 220b, from the left to the right in the figure, a 10th ring 221a, a 20th ring 221b, a 30th ring 221c, and a 40th ring 221 are arranged in order.
d and the fiftieth ring 221e are fitted.

Further, a first through hole 221b and a second through hole 221g are opened in this thin shaft portion 220b.

Furthermore, this main valve stem 220 has a sub-valve cylinder 222 as an axial hole that opens at the right end in the figure.
A large diameter portion 222a is formed at the farthest end of the sub-valve cylinder 222, which is the left end in the figure, and a small diameter portion 222b is formed at the remaining right end in the figure. .

A sub-valve stem 223 is slidably and tightly fitted into this sub-valve cylinder 222.

That is, this sub-valve stem 223 has a thick shaft portion 223a that is slidably and tightly fitted into the large diameter portion 222a at the left end in the figure, and the remaining right end portion in the figure is as follows: A thin shaft portion 223b that is slidably and tightly fitted into the thin diameter portion 222b.
Therefore, the 60th ring 2 is attached to the outer periphery of the thick shaft portion 223a.
24a, and a 70th one on the outer periphery of the thin shaft portion 223b.
A ring 224b, an 80th ring 224c, and a 90th ring 224d are fitted.

This sub-valve stem 223 is provided with an axial through hole 225 that continues from one end to the other end.
An orifice 226 is provided in the middle of the hole 5.

In addition, 227 corresponds to the main valve stem 220,
This is a spring that constantly applies an elastic force to the right in the diagram.

Therefore, the scavenging/return air cut valve 21 is in the state shown in FIG. 2 under the force of the spring 227 during normal times, that is, when pressurized air is not introduced through the eighth opening 219.

In the state shown in FIG. 2, each of the second and third openings 213,
214 is blocked, and therefore air from the air chamber 14 is blocked from blowback chamber 12, timing chamber 22, and combustion chamber 7.

Next, when the release valve 24 is switched and pressurized air from the air chamber 14 is introduced into the main valve cylinder 211 through the eighth opening 219, the valve 21 is switched to the state shown in FIG.

That is, both the main valve stem 220 and the sub-valve stem 223 are pushed to the left in the figure.

In the state shown in FIG. 3, the second opening 213 connected to the air chamber 14 is connected to the first, fourth, and fifth openings 212, 215, and 216, and further connected to the air chamber 14. The third opening 214 is the sixth opening 217
, thereby communicating with the blowback chamber 12,
Pressurized air is introduced into both the timing chamber 22 and the combustion chamber 7.

By the way, in the state shown in FIG. 3, the orifice 22
The pressurized air introduced into the left chamber side in the figure in the sub-valve cylinder 222 through the through hole 225 while being throttled by 6 and delayed eventually pushes the sub-valve stem 223 back to the right in the figure.

That is, since the left end surface of the sub-valve stem 223 in the drawing has a larger area than the right end surface in the drawing, this area difference causes the sub-valve stem 223 to be returned to the right in the drawing by pressurized air, and the sub-valve stem 223 is returned to the right in the drawing. Switch to the state shown in Figure 4.

When the state shown in FIG. 4 is reached, the first opening 212
is shut off, and the passage to the blowback chamber 12 is closed.

However, the second opening 213 and each of the fourth and fifth openings 21
5, 216, and the third opening 214 and the sixth opening 21
Therefore, even if the introduction of air into the blowback chamber 12 is cut off, the introduction of air into the timing chamber 22 and the combustion chamber 7 will continue.

Then, from the state shown in FIG. 4 above, when the release valve 24 is switched and the pressurized air to the eighth opening 219 is cut off,
The state shown in FIG. 2 is restored, and the valve 21 is switched to the shut-off state.

Here, to explain again referring to FIG. 1, the timing chamber 22, together with the orifice 25', is for delaying a signal from the scavenging/return air cut valve 21 and transmitting the signal to a release valve 24, which will be described later.

Further, the release valve 24 is formed by fitting a valve stem 242 into a half cylinder 241 in a slidable manner.

In addition, O in the figure is an O-ring, and Ll, L2゜L3
......I-'20 all indicate conduction paths.

Therefore, the operating state of the above configuration will be explained below.

First, the state before operation is the state shown in FIG. 19. That is, in the state shown in FIG.
2 to the upper chamber of the head valve 10, the head valve 10 is closed (pressed down to bottom dead center), and the combustion chamber 7 is opened.
and the upper chamber of the piston of the main cylinder 2.

Further, the exhaust valve 19 is in an open state, and the conduction path L
The combustion chamber 7 is opened to the atmosphere through the opening 20 by 3°L4.

Incidentally, in the state shown in FIG. 1, nails are previously supplied and loaded into the nose 5 from a magazine (not shown) or the like.

Further, in the state shown in FIG. 1, the scavenging/return air cut valve 21 is in the state shown in FIG.

Next, the fuel supply valve 17 in the state shown in FIG.
Switching is performed by pushing down the operating protrusion so that the stem moves to the bottom dead center.

Then, the conductive paths L5 and L6 and L7 and L8 are communicated with each other, and the combustible gas from the LPG source 16 and the air from the air chamber 14 are guided to the premixing chamber 180.

At this time, a needle valve 18 is provided between the conduit L8 and the premixing chamber 180, and the mixing ratio can be changed by adjusting the air flow rate.

Further, the premixing chamber 180 is in communication with the combustion chamber 7, and the mixed gas is supplied and filled into the combustion chamber 7.

Note that, prior to this, when the stem of the fuel supply valve 17 is pushed down, air from the air chamber 14 passes through the conduction paths Lg and Llo and acts on the left side chamber in the figure of the large diameter shaft of the stem of the exhaust pulp 19. , the stem is moved to the right in the figure due to the diameter difference, closing the gap between the conductive paths L3 and L4, and closing the combustion chamber 7 from the outside air.

In this way, the combustion chamber 7 is filled with air-fuel mixture.

The mixed gas introduced into the combustion chamber 7 from the premixing chamber 180 increases the pressure within the combustion chamber 7, and this pressure is pushed upward through the conduit Lll to the lower end surface of the stem of the fuel supply valve 17. On the other hand, this fuel supply valve 17 is pushed downward in the figure due to the diameter difference between the large diameter shaft part and the small diameter shaft part in the upper part of the stem, and the pressure inside the combustion chamber 7 is When the force pushing the stem of the supply valve 17 upward is greater than the force due to the diameter difference in the upper part of the valve stem, the valve stem is pushed upward in the figure and switched, and the valve stem is switched between the conductive paths L5 and L6. And the connection between L7 and 58 is cut off, and the fuel supply ends.

Therefore, in this state, when the piezoelectric element 9 energizes the spark plug 8, the mixed gas stored in the combustion chamber 7 is ignited, the pressure in the combustion chamber 7 increases rapidly, and the pressure below the stem of the release valve 24 is ignited. The force applied to the end face in the upward direction in the figure is caused by spring 2
When the pressure inside the combustion chamber 7 increases until it overcomes the force of 7,
The stem of the release valve 24 is pushed upward in the figure to switch.

Note that when the stem 242 of the release valve 24 is lifted even a little, the air from the air chamber 14 applies pressure to the lower surface of the large diameter shaft of the release valve 240 through the conduit L1, and the force due to this pressure is applied to the lower surface of the large diameter shaft of the release valve 240. Even after the pressure in the combustion chamber 7 drops, the stem 242 of the release valve 24 is self-held while moving to the top dead center.

Next, as the stem 242 of the release valve 24 moves upward in the figure as described above, the conduction path L2 communicating with the upper chamber of the head valve 10 and the conduction path L1 communicating with the air chamber 14 are connected. The space between the conductive paths L2 and the conductive path L1□ communicating with the atmosphere is communicated with each other.

Therefore, the upper chamber of the head valve 10 becomes atmospheric pressure, and the pressure inside the combustion chamber 7 moves the head valve 10 upward in the figure.

As a result, the combustion chamber 7 and the upper chamber of the piston in the main cylinder 2 become electrically connected, and the high-pressure combustion gas in the combustion chamber 7 flows into the upper chamber of the main piston, rapidly pushing down the main piston 3 and connecting it to the piston 3. A driver 4 is used to drive the nail that has been loaded into the nose 5 in advance.

Note that as the stem 242 of the release valve 24 has been moved upward in the figure as described above, the conduction path L13 is cut off from the atmosphere, and the air pressure from the air chamber 14 is transferred to the conduction path '
i, 15 Li2 is applied to the right end surfaces of the scavenging/return air cut valve 21 and the exhaust pulp 19 in the figure, and the stems 220, 192 of these valves 2L19 are moved to the left in the figure, but the conduit L14 and each valve 21 , 19, and after the stem 242 of the release valve 24 moves upward in the figure, the exhaust valve 19 and the scavenging/return air cut valve 21 are switched with a time delay. Accordingly, the orifice 29 is set so that the exhaust valve 19 and the scavenging/return air cut valve 21 are moved after the main piston 3 and the driver 4 have finished driving the nail.

The stem of the exhaust valve 19 moves without any load from a position where the conductive paths L4 and L3 are cut off to a position where the conductive paths L4 and L3 are opened and communicated with each other.

Combustion chamber 7 opens to the atmosphere.

In addition, as shown in FIG. 3, the scavenging/return air cut valve 21 allows combustion to flow from the air chamber 14 through the conduit path L15t''16 by moving the main valve stem 220 and the sub-node valve stem 223 to the left in the figure. Room 7
Air is blown into the combustion chamber 7 to clean the gas after combustion, and the gas is exhausted through the conduction paths L3 and L4.

Furthermore, air is also blown into the blowback chamber 12 from the conduction path L17 through the conduction path L19, blowing up the main piston 3 at the bottom dead center toward the top dead center.

At this time, when the valve 21 is delayed and eventually switches to the state shown in FIG. 4, air to the blowback chamber 12 is cut off, thereby preventing blowback near loss.

Incidentally, at the same time as the main piston 3 blows up, air also flows into the timing chamber 22 from the conduit path L1□ through the conduit path L18 and the orifice 25'.

By the way, since this air passes through the orifice 25', it gradually accumulates in the timing chamber 22, and this pressure passes through the conduit path L20 to the stem 24 of the release valve 24.
It rests on the upper surface of the large diameter shaft of No.2.

When the sum of the force due to this pressure and the force of the spring 270 becomes greater than the upward force applied to the lower surface of the large diameter shaft of the stem 242 of the release valve 24, the stem of the release valve 24 is pushed down in the figure and switched. The state returns to the state shown in FIG.

The diameter of the orifice 25' and the volume of the timing chamber 22 are adjusted so that the release valve 24 is pushed back downward in the figure after the main piston 3 returns and the combustion chamber 7 is properly scavenged. Just set it.

Then, when the stem 242 of the release valve 24 falls to the bottom dead center as shown in FIG.
Pressure is applied to the upper chamber of the head valve 10 through L2, and the head valve 10 lowers to the bottom dead center, cutting off the combustion chamber 7 and the upper chamber of the piston in the main cylinder 2.

At the same time, the right end faces of the scavenging/return air cut valve 21 and the exhaust valve 19 in the drawings become atmospheric pressure through the conduction path L13゜L1□, and the scavenging/return air cut valve 21 becomes atmospheric pressure.
The main stem 220 of No. 1 is moved rightward in the figure by the pressure of the spring 227 and returns to the state shown in FIG. 2.

Due to this switching of the scavenging/return air cut valve 21, the air in the timing chamber 22 is released to the atmosphere through the bypass conduit A, 7, and returns to the state before operation as shown in FIG. 1 - the cycle ends. .

Note that the present invention is not limited to the above embodiments,
Furthermore, various other modifications are possible.

As is clear from the above, in the present invention, air can be used efficiently and the intended purpose can be fully achieved.

[Brief explanation of the drawing]

The drawings are cross-sectional views schematically showing an embodiment of the present invention, and FIG. 1 shows a state before operation - a normal state. Figures 2 to 4 are longitudinal cross-sectional views of essential parts of the scavenging/return air cut valve, with Figure 2 showing the normal-cutoff state, Figure 3 showing the conducting state, and Figure 4 showing the blow-off state. Only the back air is blocked. 1... Housing, 2... Main cylinder, 3... Main piston, 7...
Combustion chamber, 10...Head valve, 12...
... Blowback chamber, 14 ... Air chamber, 15 ... Air source, 16 ... LP
G source, 17... Combustion supply valve, 18...
... Needle valve, 180 ... Premixing chamber, 1
9...exhaust valve, 21...-scavenging/return air cut valve, 22...timing chamber, 24...M removal valve, 25/, 29
...orifice.

Claims (1)

[Claims] 1. A main cylinder, a main piston slidably and tightly fitted into the main cylinder, a driver integrally connected to the main piston, a combustion chamber, and an opening/closing mechanism between the combustion chamber and the piston upper chamber of the cylinder. A head valve to be operated, a blowback chamber communicating with the lower piston chamber of the cylinder, selectively blocking or conducting between the combustion chamber and the air chamber, and selectively blocking or conducting between the air chamber and the blowback chamber. a scavenging air/return air cut valve for electrical conduction; an exhaust valve for selectively blocking or electrical continuity between the combustion chamber and the exhaust port opening to the atmosphere; and a first position for electrically conducting between the upper chamber of the head valve and the air chamber. and a second air chamber that communicates between the air chamber, the scavenging/return air cut valve, and the exhaust valve.
a release valve which takes the first position in normal times and switches to the second position in response to combustion chamber pressure during combustion, and the return driving air for the release valve is connected to the scavenging/return air. a timing chamber in which scavenging air is stored through a cut valve, and the scavenging/return air cut valve has first and second openings that communicate with the air chamber, a third opening that communicates with the blowback chamber, and a timing chamber that communicates with the combustion chamber. a valve cylinder having a fourth opening in communication with the timing chamber, fifth and sixth openings in communication with the timing chamber, each having a release valve at one end thereof and a seventh opening in selective communication with the air chamber; A main valve stem consisting of a large diameter part and a small diameter part is slidably and tightly fitted into this cylinder, and a sub-valve cylinder that opens at one end of the stem is bored in this main valve stem. A sub-valve stem consisting of a large-diameter part and a small-diameter part is slidably and tightly fitted into the sub-valve cylinder, and the sub-valve stem has a through-axial hole with a constricted part in the middle. Each of the valve stems is normally located toward one end, and is located between the air chamber and the blowback chamber, between the air chamber and the combustion chamber, and between the air chamber and the timing chamber. takes the first position where it is in a cutoff state, and when air pressure is introduced from the seventh opening, each of the main valve stem and sub-valve stem switches to the other end side and blowbacks with the air chamber. The chamber, the combustion chamber, and the timing chamber are brought into contact with each other at a second position, and the valve stem is moved from the second position by air pressure acting on the upper surface of the large diameter portion of the sub-valve stem through the inside of the through-axis direction. Only the sub-valve stem is switched in one direction so that only the third opening communicating with the blowback chamber is connected to the first opening.
and a third position blocking the second opening;
When the supply of air to the opening of the valve is cut off, the scavenging/return air cut valve returns to the first position, and conductive air pressure at the second position of the scavenging/return air cut valve is introduced into the timing chamber through the constriction part. An internal combustion type device characterized in that the release valve in the second position is switched to the first position by causing air in the timing chamber to act on the release valve.