Shaft engine

A shaft engine including a piston moved in a cylinder to reciprocate at least one cylinder shaft causing it to turn a crank shaft, the at least one cylinder shaft having a respective longitudinal air passage linked to either raised air chamber on the cylinder through a respective extension tube on either raised air chamber for sending exhaust gas out of the cylinder.

BACKGROUND OF THE INVENTION 
The present invention relates to a shaft engine having cylinder shafts 
reciprocated by the piston thereof to move a crank shaft for power output, 
wherein the cylinder shafts comprise air passages for guiding a fuel gas 
into the cylinder and for sending exhaust gas out of the cylinder 
respectively. 
The engine of a motor vehicle is generally comprised of a cylinder having a 
piston or pistons reciprocated, by means of the burning of a fuel gas in 
the cylinder, to turn a crank shaft. This structure of engine further 
comprises an exhaust piping system, intake and exhaust valves, and an 
exhaust cam. Therefore, this structure of engine is complicated and 
difficult to maintain. Because of a complicated structure, the 
manufacturing cost and weight of this engine are relatively increased. 
Further, in a two stroke engine, the exhaust and intake strokes are 
simultaneously performed when the piston is moved to the lower limit, and 
therefore the problem of low combustion efficiency and high exhaust 
emissions cannot be eliminated. 
SUMMARY OF THE INVENTION 
The present invention eliminates the aforesaid drawbacks. It is one object 
of the present invention to provide a shaft engine which is simple in 
structure, lightweight, and inexpensive to manufacture. It is another 
object of the present invention to provide a shaft engine which is easy to 
maintain, and durable in use. It is still another object of the present 
invention to provide a shaft engine which is efficient in operation. It is 
still another object of the present invention to provide a shaft engine 
which greatly saves the consumption of fuel gas. It is still another 
object of the present invention to provide a shaft engine which greatly 
reduces exhaust emissions. 
According to one embodiment of the present invention, the shaft engine 
comprises a piston moved in a cylinder to reciprocate a plurality of 
cylinder shafts causing them to turn a crank shaft, wherein the cylinder 
shafts have a respective longitudinal air passage linked to either raised 
air chamber on the cylinder through a respective extension tube on either 
raised air chamber for sending exhaust gas out of the cylinder and guiding 
a fuel gas into the cylinder respectively.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIGS. 1 and 2, a shaft engine in accordance with the present 
invention is generally comprised of a piston 10 made to slide in a 
cylinder 40, a first pair of shafts 20;200 and a second pair of shafts 
30;300 symmetrically fastened to the piston 10, a plurality of piston 
rings 11;12 mounted around the periphery of the piston 10 and closely 
touching the inside wall 41 of the cylinder 40. The first pair of shafts 
20;200 are identical in shape, each having two I/O (input/output) air 
holes 21 or 24 at two opposite ends. Seal rings 22;23 or 25;26 are 
respectively mounted within the I/O air hole 21 or 24 of either shaft 20 
or 200. The cylinder 40 comprises air chambers 44;45;46;47 at two opposite 
sides 42;43 thereof, two upper extension tubes 440;460 and two lower 
extension tubes 450;470 respectively extended outwards from the air 
chambers 44;45;46;47 which receive the shafts 20;200. The upper extension 
tubes 440;460 at the top side are linked by a transverse tube 48. The 
first shafts 20;200 extend out of the lower extension tubes 450;470, and 
are connected to a crank shaft 49 (see FIG. 7). An intake pipe 400 is 
connected to the cylinder 40. When the piston 10 is moved to the upper 
limit (see FIG. 1), it is disposed at a slightly higher elevation above 
the intake pipe 400. Two spark plugs 50;60 are mounted on the cylinder 40 
at the top and bottom sides. The extension tubes 440;450;460;470 comprise 
a respective through hole 441;451;461;471 in communication with either air 
chamber 44;45;46;47. 
Referring to FIG. 3 and FIG. 1 again, one shaft 30 of the second pair of 
shafts has a longitudinal oil passage 31 through its upper part disposed 
in communication with the inside space 13 of the piston 10 through a hole 
14 on the piston 10; the other shaft 300 of the second pair of shafts has 
a longitudinal oil passage 301 through its lower part disposed in 
communication with the inside space 13 of the piston 10 through a hole 15 
on the piston 10 to provide a passage way for oil cooling. Seal rings 
32;33;302;303 are respectively mounted around the shafts 30;300 and 
closely touching the inside wall of either extension tube 440 or 470. 
Referring to FIG. 4, therein illustrated is an alternate form of the piston 
10 in which the piston 20 is comprised of two symmetrical parts 107;109 
separated by a space communicated between the longitudinal oil passages 
31;301. 
Referring to FIGS. 5 and 6, when the piston is moved to the upper limit, a 
fuel gas is guided from the intake pipe 400 into the inside space of the 
cylinder 40. When the piston is moved downwards, the fuel gas inside the 
cylinder 40 is compressed and burnt by the spark plug 60 at the bottom to 
induce an explosion stroke. 
Referring to FIG. 7, when the piston 10 is moved to the lower limit, the 
air holes 21 of the first pair of shafts 20;200 are respectively 
communicated with the through holes 441;461 of the upper extension tubes 
440;460 for permitting exhaust gas to escape out of the cylinder 40 
through the first pair of shafts 20;300 and the transverse tube 48. At the 
same time, a flow of the fuel gas is guided into the cylinder 40 from the 
intake pipe 400. When the piston 10 is moved upwards to compress the fuel 
gas, another stroke is performed, and power is sent out through the crank 
shaft 49. 
Referring to FIG. 8, therein illustrated is an alternate form of the 
present invention, in which one shaft 20 is made to guide the fuel gas 
into the cylinder; another shaft 200 is made to guide exhaust gas out of 
the cylinder. This arrangement eliminates the installation of the intake 
pipe. According to this alternate form, the shaft 20 or 200 has an upper 
air hole 210 or 201 near the top in the radial direction and a lower air 
hole 250 or 202 in the middle. When the piston 100 is moved to the upper 
limit, the fuel gas is guided into the cylinder; when the piston 100 moves 
downwards, the fuel gas in the cylinder is compressed; when the piston 100 
is moved to the lower limit, the upper air holes 210;201 are opened for 
letting the fuel gas to enter the cylinder and exhaust gas to escape out 
of the cylinder; when the piston 100 moves upwards, the fuel gas is 
compressed again. 
Referring to FIG. 9, therein illustrated is still another alternate form of 
the present invention arranged to use a conventional top-mounted spark 
plug; the shafts 207;209 of the piston 101 have radial holes at two 
opposite ends respectively fastened with seal rings. This arrangement 
allows the cylinder to take in the fuel gas and release exhaust gas. 
Referring to FIG. 10, therein illustrated is still another alternate form 
of the present invention, in which a conventional piston 101 is used; the 
cylinder has an intake pipe at one side through which the fuel gas is sent 
into the cylinder; the two shafts 206;208 which are reciprocated by the 
piston 101 are linked by a transverse tube 480 for sending exhaust gas out 
of the cylinder. 
In the embodiments shown in FIGS. 1 through 8, an output of power is 
produced upon each down or up stroke. The embodiments shown in FIGS. 9 and 
10 are two stroke engines. Either embodiment of the present invention 
eliminates the installation of crank shaft, intake and exhaust air valves, 
and the related linking mechanism.