JPS5814592B2 - safety valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention can be used, for example, when a gas combustion chamber is to be filled with compressed air supplied from an air source and propane gas supplied from a combustible gas source such as a gas cylinder as a mixture. Concerning a useful safety valve.

Recently, attempts have been made to utilize combustion gas pressure for driving force in order to obtain large outputs for impact tools and the like.

For example, a mixture of propane gas and compressed air is combusted and exploded in a combustion chamber, and the resulting pressure is applied to a piston to drive the working end.

In that case, the combustion chamber must be filled with a mixture of combustible gas and air at a suitable mixing ratio.

If the above-mentioned combustible gas pressure or compressed air pressure fluctuates, it will not be possible to obtain a mixed gas with a suitable mixing ratio, resulting in mis-ignition or incomplete combustion, which will cause the internal combustion type tool mentioned above to become unable to drive or drive incorrectly. cause a situation.

In particular, the pressure of combustible gas changes depending on the temperature, and when the compressed air pressure becomes zero, only fuel will flow.

Therefore, in order to operate the combustion safely, the combustible gas and compressed air must be constantly maintained at the same pressure.

Therefore, the present invention works to supply two fluids such as the above-mentioned combustible gas and compressed air, but when the compressed air does not flow, the combustible gas does not flow, and the pressure of the combustible gas is significantly lower than that of the compressed air. The purpose of this invention is to provide a safety valve that acts to prevent flammable gas from flowing in the event of an accident.

That is, the safety valve of the present invention includes first and second fluid sources, mixing means for mixing the first and second fluids supplied from the fluid sources, and the first and second fluid sources and the mixing means. and a sub-valve stem that compares the fluid pressures of the first and second fluids, and a sub-valve stem that compares the fluid pressures of the first and second fluids. The main valve stem is characterized by having a main valve stem that shuts off communication between the second fluid source and the mixing means when a low pressure state is detected, and switches the communication between the second fluid source and the mixing means when a low pressure state is detected. It is configured to do so.

This will be explained below with reference to the drawings.

Note that the drawing is a schematic longitudinal sectional side view of a main part showing one embodiment of the present invention, and when attempting to obtain an air-fuel mixture by supplying compressed air as the first fluid and combustible gas as the second fluid. It is a safety valve.

In the figure, 1 is a housing constituting the main body of the internal combustion tool, and 2 is a valve cylinder built into the housing.

This cylinder 2 has an opening 2a to the atmosphere at the left end in the figure, and a communication port 2b at the right end in the figure.

Note that this communication port 2b communicates with a compressed air passage 3 bored in the housing 1.

The compressed air conduit 3 has a lower end 3a in the figure communicated with a compressed air source such as an air chamber (not shown), and an upper end 3b in the figure communicated with mixing means such as a mixing valve (not shown).

In addition, a first communication passage 4 communicating with a combustible gas source such as a gas cylinder (not shown) and a second communication passage 5 communicating with the mixing valve (not shown) are opened in the peripheral wall of the valve cylinder 2, and an opening to the atmosphere is provided. 6 is provided.

Furthermore, 7 is a main valve stem, which is tightly fitted into the cylinder 2 so as to be able to move left and right in the figure.

A sub-cylinder 70 that opens at the right end in the figure is coaxially bored in the main valve stem 7, and a protruding shaft that protrudes to the right in the figure is formed on the left end wall of the sub-cylinder 70 in the figure. 71 is provided.

Further, the main valve stem 7 has first, second, and third through holes 72, 73, and 74 that are connected to the sub cylinder 7.
Particularly, the first through hole 72 is formed in the peripheral wall 75 located on the outer periphery of the protruding shaft 71, the second through hole 73 is formed in the middle peripheral wall 75, and the third through hole 74 is formed in the peripheral wall 75 located on the outer periphery of the protruding shaft 71. It is positioned to the right of the second through hole 73 in the figure.

Note that 8 is a spring, which urges the main valve stem 7 to the right in the figure.

Next, 9 is a sub-valve stem, which is slidably and tightly fitted into a sub-cylinder 70 formed in the main valve stem 7.

On the outer periphery of this sub-valve stem 9, there are first, second and third O-rings 91, 9 which face from the left to the right in the figure.
2 and 93 are fitted in a dispersed manner, and a first reduced diameter portion 94 is provided between each of the first and second O-rings 91 and 92, and a second and third
A second reduced diameter portion 95 is formed between the O-rings 92 and 93, and a third reduced diameter portion 96 is formed to the right of the 30th ring 93.

Therefore, in the above configuration, the operation will be explained below.

First, the state shown in FIG. 1 is a case where no air flows into the compressed air guide path 3, or a normal state.

In the state shown in FIG. 1, both the main valve stem 7 and the sub-valve stem 9 are biased to the right in the figure by the elastic force of the spring 8.

Therefore, the communication between the first and second communication paths 4 and 5 is blocked, and the flow of combustible gas is prevented.

Next, Fig. 2 shows the situation when air is flowing into the compressed air conduit 3 and the air pressure in the passage 3 is slightly lower than or the same pressure as the combustible gas pressure. .

That is, the air pressure flowing in the compressed air conduit 3 is transferred from the communication path 2b to the stem right chamber 20 in the main valve cylinder 2.
a to press and move the main valve stem 7 to the left in the figure against the elastic force of the spring 8.

Then, the main valve stem 7 establishes communication between the first and second communication passages 4 and 5 via the left chamber 70a of the sub-valve stem 9 in the sub-cylinder 70 and the first communication hole 72. Switch to

Note that at this time, the sub-bulp stem 9 receives combustible gas pressure on the left side in the figure, that is, in the left chamber 70a, so the first
It is in the same position as in the figure.

Therefore, in the state shown in FIG. 2, air is supplied from the compressed air conduit passage 3 and combustible gas is supplied to the unillustrated mixing valve via the first and second communication passages 4 and 5, and the air-fuel mixture is can be obtained.

Next, FIG. 3 shows a case where after air and combustible gas are supplied simultaneously under the condition shown in FIG. 2, the combustible gas pressure becomes lower than the air pressure.

That is, as the combustible gas pressure decreases, the sub-valve stem 9, which was in the position shown in FIG. Pressed and moved to the center left.

Then, the first through hole 72 of the main valve stem 7 connects with each of the first and second O-rings 91 and 92 of the sub-valve stem 9.
The outer periphery of the first reduced diameter portion 94 between the first and second diameter portions is opposed and sealed.

Therefore, the communication between the first and second communication paths 4 and 5 is cut off, and the inflow of flammable gas can be stopped.

As mentioned above, the air pressure sent to the mixing means from the compressed air conduit 3 and the combustible gas pressure sent from the first communication path 4 to the mixing means through the second communication path 5 are applied to both sides of the sub-valp stem 9. The main valve stem 7 receives the air pressure and compares these pressures, and the main valve stem 7 switches in response to the above air pressure (see Figures 2 and 3).
As shown in the figure), the combustible gas flow path is turned on and off by compressed air pressure, and the combustible gas flow path is turned on and off by the differential pressure between the combustible gas pressure and the compressed air pressure.

Therefore, when a pressure difference occurs between the combustible gas and the air, the combustible gas is cut off, allowing safe combustion operation.

Therefore, in the valve of the present invention, since the main valve stem and the sub-valve stem can be constructed in the form of coaxial rear shafts, the entire device can be formed compactly, so that the valve has an advantageous design even when it is incorporated into the body of an internal combustion tool. becomes possible.

Note that the present invention is not limited to the above embodiments,
A first and second fluid source, a mixing means for mixing the first and second fluids supplied from the fluid sources, and a valve provided between the fluid sources and the mixing means. and a sub-valp stem for comparing the fluid pressures of the first and second fluids, and a sub-valp stem for detecting a state in which the first fluid pressure is higher than the first fluid pressure. Further, the present invention is characterized by having a main valve stem that sometimes cuts off the connection between the second fluid source and the mixing means and switches the communication between the second fluid source and the mixing means when a low pressure condition is detected. Various modifications are also possible.

[Brief explanation of drawings]

Each of the drawings is a schematic longitudinal sectional side view of a main part showing an embodiment of the present invention, and FIG. 1 shows a state in which neither air nor combustible gas is flowing, and FIG. 2 shows a state in which both air and combustible gas are flowing. Figure 3 shows a state where only air is flowing and no combustible gas is flowing. 2... Main valve cylinder, 3...
Compressed air conduction path, 4... First communication path, 5...
...Second communication passage, 7...Main valve stem, 8...Spring, 9...Sub valve stem.

Claims (1)

[Claims] 1. A first and second fluid source, a mixing means for mixing the first and second fluids supplied from the fluid sources, and a mixing means provided between the fluid sources and the mixing means. and a sub-valp stem that compares the fluid pressures of the first and second fluids, and the sub-valp stem detects a state in which the first fluid pressure is higher. 1. A safety valve characterized by having a main valve stem that cuts off communication between the second fluid source and the mixing means when a low pressure state is detected, and switches the main valve stem to communicate with the second fluid source when a low pressure state is detected.