WO2005068806A1

WO2005068806A1 - Cam and hump track type engine

Info

Publication number: WO2005068806A1
Application number: PCT/KR2005/000113
Authority: WO
Inventors: Yong Suk Kim
Original assignee: Mission Foundation Of The Family Federation For World Peace And Unification
Priority date: 2004-01-19
Filing date: 2005-01-13
Publication date: 2005-07-28

Abstract

The present invention relates to a cam and hump track type engine comprising: a casing radially disposed with a plurality of cylinders about a cam case or a hump track case; pistons reciprocating within the cylinders; a cam or a hump track part mounted on an output shaft disposed at a center of the cam case or the hump track part; a main roller (a first roller) and an auxiliary roller (a second roller) rotatably mounted at the piston for riding and rolling along the cam or the hump track part, wherein the auxiliary roller rides along the track groove of the hump track part to raise or lower the piston, such that an output shaft can smoothly rotate to promote a greater yield in a compact light-weight small engine.

Description

CAM AND HUMP TRACK TYPE ENGINE

FIELD OF THE INVENTION

The present invention relates to a cam and hump track type engine and, more

particularly, to a cam and hump track type engine having a roller mounted at a piston.

BACKGROUND OF THE INVENTION

Gasoline and diesel engines according to the prior arts have a piston-

crankshaft mechanism. The piston-crankshaft mechanism converts the linear motion

of the piston into rotational motion through the connecting rod. A four-stroke-cycle

engine makes one explosion while a four-stroke-cycle of intake, compression,

expansion and exhaust is carried out during a crankshaft effecting two times of rotation

while a piston moves back and forth two times.

There is a disadvantage in obtaining a large output in the engine thus described because one time of explosion is effected while a piston is reciprocated two times.

There is another disadvantage in that the inertia force of a connecting rod is effected on the piston as lateral pressure in addition to the reaction force of an output torque, to enhance a maximum value of the lateral pressure and friction and impact to a cylinder wall. There is still another disadvantage in that forces of respectively different directions are continuously applied to a connecting portion between the connecting rod,

the piston and the crankshaft such that a material of high strength, rigidity and yielding

point is required and the manufacturing cost cannot be reduced.

There is still a further disadvantage in that since the connecting rod and

crankshaft are used, the engine cannot be miniaturized in size and lightened in weight.

As a way of overcoming the disadvantages of the reciprocating engine thus

described, there is disclosed a conventional cam type engine by Japanese Patent

Publication No. Hei-08-004550.

Referring to FIGS. 1 and 2, Japanese Patent Publication No. Hei-08-004550

includes a casing (1) integrally formed with two cylinders (4) each radially opposingly

facing at 180 degrees interval around a cam case (2), an output axis (6) so mounted as

to be extended into the cam case (2), a cam (8) having even numbers of cam crests (8a, 8b) each disposed at an equidistance and also having a rim (8c) along a cam curvature to be mounted inside the cam case (2), a piston (16) slidably mounted inside the cylinders (4) and rotatably supporting a main roller (10) and auxiliary rollers (12,14) each internally and externally contacting a rim (8c) of the cam (8), and suction/exhaust means (18, 20) and ignition means (22) respectively mounted at each cylinder (4).

In the cam having a curved surface in the conventional cam type engine disclosed in Japanese Patent Publication No.Hei-08-004550, the main roller (10) and the auxiliary rollers (12, 14) each radially located in a different distance from the center of the cam form dissimilar tracking curvature lines of the centers of the rollers

whereas two tracking curvatures may overlap in some regions. Accordingly, there is

a drawback in that the main roller (10) and the auxiliary rollers (12, 14) being mounted

on a central axial line of the piston (16) and the rim (8c) of the cam being interposed

between the rollers cause the cam to be jammed and the output shaft inoperable for

rotation, thereby rendering the engine inoperable.

SUMMARY OF THE INVENTION

The present invention is disclosed to address the problem of the conventional

cam type engine, and the object of the present invention is to provide a cam and hump

track type engine configured to allow an output shaft fixed with a cam to be smoothly

rotated in a cam type engine with a main roller and auxiliary rollers being disposed at a

piston. In accordance with one embodiment of the invention, there is provided a cam and hump track type engine comprising; a casing radially disposed with a plurality of cylinders about a cam case; pistons reciprocating within said cylinders, a cam mounted on an output shaft disposed at a center of said cam case; a main roller externally contacting said cam and rotatably mounted at each said piston; and auxiliary rollers disposed at said piston for lowering said piston and for preventing said main roller from being drailed from a peripheral surface of said cam, wherein said output shaft

mounted with said cam has a hump track part formed with a track groove along where

said auxiliary rollers ride.

In accordance with another embodiment of the invention, there is provided a

cam and hump track type engine comprising: a casing radially disposed with a

plurality of cylinders about a cam case; pistons reciprocating within said cylinders; a

cam provided on an output shaft disposed at a center of said cam case; two rollers

externally contacting said cam and rotatably mounted at each said piston; and a ball

rod disposed at said piston for lowering said piston and for preventing said rollers from i being derailed from a peripheral surface of said cam, wherein said cam is formed at

both sides thereof with track surfaces where said two rollers respectively externally

contact and roll along, and said cam is centrally formed with a hump track part having

a track groove into which a ball part of said ball rod is slidingly inserted.

In accordance with still another embodiment of the present invention, there is provided a cam and hump track type engine comprising: a casing radially disposed with a plurality of cylinders about a cam case; pistons reciprocating within said cylinders; a cam provided on an output shaft disposed at a center of said cam case; a main roller externally contacting said cam and rotatably mounted at each said piston; and auxiliary rollers disposed at said piston for lowering said piston and for preventing said main roller from being derailed from a peripheral surface of said cam, wherein said cam is provided with a hump track part formed with a track groove along where

said auxiliary rollers ride and roll, and said main roller and said auxiliary rollers are

arranged along the same axis.

In accordance with a further embodiment of the present invention, there is

provided a cam and hump track type engine comprising: a casing radially disposed

with a plurality of cylinders about a hump track case; pistons reciprocating within said

cylinders; a first and a second hump track part each spaced a predetermined distance

apart from an output shaft disposed at a center of said hump track case and said first

and second hump track part each formed at an inner surface thereof with a track

groove; a first roller coupled to a lower portion of said piston for riding and rolling

along said track groove of said first hump track part so as to raise and lower the piston;

and a second roller coupled to the other lower portion of said piston for rolling and

riding along said track groove of said second hump track part so as to raise and lower

said piston.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the nature and objects of the present invention, reference should be made to the following detailed description with the accompanying drawings, in which: FIG. 1 is a schematic front elevational sectional view of a conventional cam

type engine;

FIG. 2 is a schematic side elevational sectional view of the cam type engine of

FIG.1; FIG. 3 is a schematic front elevational sectional view of a cam and hump track

type engine according to a first embodiment of the present invention;

FIG. 4 is a schematic side elevational sectional view of a cam and hump track

type engine according to the first embodiment of the present invention;

FIG. 5 is a schematic view of a track surface of a cam along where a main

roller of a cam and hump track type engine rides and moves, and a track groove of a

hump track part along where an auxiliary roller rides and moves according to the

present invention;

FIG 6 is a schematic front elevational sectional view for illustrating an operation of a cam and hump track type engine according to the first embodiment of the present invention;

FIG. 7 is a schematic view for illustrating an operation of a cam and hump track type engine according to the present invention;

FIG. 8 is a schematic front elevational sectional view of a cam and hump track type engine according to a second embodiment of the present invention; FIG. 9 is a schematic side elevational sectional view of a cam and hump track type engine according to a second embodiment of the present invention;

FIG. 10 is a schematic front elevational sectional view of a cam and hump

track type engine according to a third embodiment of the present invention;

FIG. 11 is a schematic side elevational sectional view of the cam and hump

track type engine of FIG. 10;

FIG. 12 is a schematic view of a track surface of a cam along where a roller of

a cam and hump track type engine rides and moves, and a track groove of a hump track

part along where a ball part of a ball rod slides according to the third embodiment of

the present invention; FIG. 13 is a schematic front elevational sectional view for illustrating an

operation of a cam and hump track type engine according to the third embodiment of

the present invention;

FIG. 14 is a schematic front elevational sectional view of a cam and hump

track type engine according to a fourth embodiment of the present invention; FIG. 15 is a schematic side elevational sectional view of the cam and hump track type engine of FIG. 14;

FIG. 16 is a schematic front elevational sectional view for illustrating an operation of the cam and hump track engine according to the fourth embodiment of the present invention; FIG. 17 is a schematic front elevational sectional view of a hump track type engine according to a fifth embodiment of the present invention;

FIG. 18 is a schematic side elevational sectional view of the hump type engine

of FIG. 17; and;

FIG. 19 is a schematic front elevational sectional view for illustrating an

operation of the fifth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiments of the present invention will now be described in

detail with reference to the annexed drawings, where the present embodiments are not

limiting the scope of the present invention but is given only as an illustrative purpose.

Referring to FIGS. 3 and 4, the cam and hump track type engine according to

the first embodiment of the present invention includes a casing (30) radially and

integrally disposed with four cylinders (34) at every 90 degrees about a cam case (32),

pistons (36) reciprocating within the cylinders (34). A cam (40) is fixed by a key (42)

on an output shaft (38) disposed at a center of the cam case (32). A main roller (44) externally contacting a track surface (peripheral surface: 40a) of the cam (40) is

rotatably mounted at the piston (36). Auxiliary rollers (46, 48) are disposed at the piston (36) for pulling down the piston (36) and for preventing the main roller (44) from being derailed from a track surface (peripheral surface) of the cam (40). Furthermore, the cam (40) is disposed at both axial sides thereof with hump

track parts (50, 52) having track grooves (50a, 52a) along where the auxiliary roller

(46) rides and rolls, and where the hump track parts (50, 52) are fixed by the key (42)

on the output shaft (38) and fixed to a lateral surface of the cam (40) by a bolt (not

shown). The cam (40) and the hump track parts (50, 52) may be integrally formed.

Each cylinder (34) is mounted with suction/exhaust means having

suction/exhaust valves (56, 58) and ignition means having an ignition plug (60). The

cylinder (34) in a diesel engine is disposed with suction/exhaust means and fuel

injection means. The^'output shaft (38) is rotatably supported at the cam case (32) by

a bearing (62).

The piston (36) is centrally concaved at its bottom portion and both sides of

the bottom portion are formed with flanges (36a, 36b). The main roller (44) is

rotatably mounted between the flanges (36a, 36b) by a first pin (64). Both the flanges (36a, 36b) are disposed thereunder with the auxiliary rollers (46, 48) rotatably mounted

by second pins (66, 68). The auxiliary rollers (46, 48) are coupled to an external surface of the flanges (36a, 36b), and the track grooves (50a, 50b) are formed at an inner surface of the hump track parts (50, 52). Preferably, the main roller (44) and the auxiliary rollers (46, 48) are rotatably coupled by roller bearings inserted outside of the first pin (64) and the second pins (66, 68). The cam (40) is formed with four cam crests, each spaced at 90 degrees apart, and is laterally formed with a projection (40b) closely contacting the hump track parts

(50, 52). The number of cam crests may vary and the shapes thereof may be variably

manufactured. The number of cylinders may also vary.

Referring to FIG. 5, the track surface (40a) where the main roller (44)

externally contacts, rides and moves, and the track grooves (50a, 52a) along where the

auxiliary rollers (46, 48) ride and roll, are not alike but may be overlapped at some

regions thereof. The track surface (40a) and the track grooves (50a, 52a) become

dissimilar according to the cam curvatures, sizes of the main roller and auxiliary rollers,

and distances from the center of the output shaft to the bottom dead center of the piston

and from the center of the output shaft to the upper dead center of the piston.

The operation of the cam and hump track type engine thus described according

to the first embodiment of the present invention will now be explained.

When the piston (36) at an upper side as shown in Fig. 3, is referred to as a first piston, other pistons are referred to as a second, a third and a fourth piston in counterclockwise order. The pistons are operated in the same manner as shown in FIG. 7.

When the output shaft (38) is rotated, and the cam (40) and hump track parts

(50, 52) are rotated counterclockwise, the piston (36) is lowered along the cam crest by the main roller (44) rolling along the track surface (40a) of the cam (40) and the auxiliary rollers (46, 48) riding on the track grooves (50a, 52a) of the hump track parts (50, 52), as in FIG. 3, to open the suction valve (56), thus, allowing air-fuel mixture to

be infused into the cylinder (34) and reach the bottom dead center of FIG. 6. The cam

(40) and the hump track parts (50, 52) are further rotated to raise the piston (36) and to

compress the air-fuel mixture in the cylinder (34), and the mixture is ignited by the

ignition plug (60) at the upper dead center to explode and expand.

The piston (36) is again lowered to arrive at the bottom dead center, and rises

again to allow the exhaust gas in the cylinder (34) to be exhausted via the exhaust

valve (58) as depicted in FIG. 3. While the cam (40) and the hump track parts (50,

52) are rotated one time as mentioned above, four pistons (36) make two

reciprocations to effect a four-stroke cycle of suction, compression, expansion and

exhaust.

Referring now to FIGS. 8 and 9, a cam and hump track type engine according

to the second embodiment of the present invention includes a casing (130) radially and

integrally disposed with four cylinders (134) at every 90 degrees about a cam case

(132), and pistons (136) reciprocating within the cylinders (134). A cam (140) is fixed by a key (142) on an output shaft (138) disposed at a center of the cam case (132). A main roller (144) making an external contact with a track surface (peripheral surface: 140a) of the cam (140) is rotatably mounted at the piston (136). Auxiliary rollers (146, 148) are disposed at the piston (136) for pulling down the piston (136) and for preventing the main roller (144) from being derailed from a track surface (peripheral surface) of the cam (140).

Furthermore, the hump track parts (150., 152) having track grooves (150a,

152a) where the auxiliary roller (146) rolls are integrally formed at both axial sides of

the cam (140). The hump track parts (150, 152) may be separated from the cam (140)

to be fixed to the output shaft (138) by a key, or may be fixed to a lateral surface of the

cam (140) by a bolt.

Each cylinder (134) is mounted with suction/exhaust means having

suction/exhaust valves (156, 158) and ignition means having an ignition plug (160).

In case of a diesel engine, the cylinder (134) is disposed with suction/exhaust means

and fuel injection means. The output shaft (138) is rotatably supported in the cam

case (132) by a bearing (162).

The piston (136) is centrally concaved at the bottom thereof and both sides of

the bottom side are formed with flanges (136a, 136b). The main roller (144) is

rotatably mounted between the flanges (136a, 136b) by a first pin (164). Both the

flanges (136a, 136b) are disposed thereunder with the auxiliary rollers (146, 148) rotatably mounted by second pins (166, 168). The auxiliary rollers (146, 148) are coupled to an internal surface of the flanges (136a, 136b), and the track grooves (150a,

150b) are formed at an external surface of the hump track parts (150, 152).

Preferably, the main roller (144) and the auxiliary rollers (146, 148) are rotatably coupled by roller bearings to be intserted outside of the first pin (164) and the second pins (166, 168).

The cam (140) is formed with four cam crests, each spaced at 90 degrees apart,

and the number of cam crests may very and the shapes thereof may be variably

manufactured. The number of cylinders may also vary. Traces of the track surface (140a) of the cam and the track grooves (150a,

152a) of the hump track parts are the same as shown in FIG. 5. The operation of the

cam and hump track type engine according to the second embodiment of the present

invention is the same as that of the first embodiment such that an explanation thereto

will be omitted. In the cam and hump track type engine according to the first and second

embodiments of the present invention, one explosion occurs in the respective four

cylinders while the cam (40, 140) and the hump track parts (50, 52, 150, 152) are

rotated one time to enable to lighten the weight of the engine and produce an enhanced output. Furthermore, the cams (40, 140) and the hump track parts (50, 52, 150, 152) are rotated one time with respect to two times of reciprocation for each piston (36, 136) such that the output shafts (38, 138) are decreased in rotations thereof, thereby restraining the output rotation number and generation of heat and vibrations, and increasing the energy conversion efficiency. Referring now to FIGS. 10 and 11, a cam and hump track type engine according to the third embodiment of the present invention includes a casing (230)

radially and integrally disposed with four cylinders (234) at every 90 degrees about a

cam case (232), and pistons (236) reciprocating within the cylinders (234). A cam

(240) fixed by a key (242) on an output shaft (238) is disposed at a center of the cam

case (232). Two rollers (244, 245) externally contacting a track surface (peripheral

surface) of the cam (240) is rotatably mounted at the piston (236). A ball rod (246) is

disposed at the piston (136) for pulling down the piston (236) and for preventing the

rollers from being derailed from a track surface (peripheral surface) of the cam (240).

The cam (240) is formed at both axial sides thereof with track surfaces (248,

250) where the two rollers (244, 245) can externally contact and roll along, and is

centrally (between both track surfaces) formed with a hump track part (252) having a

track groove (252a) where a ball part (described later) of the ball rod (246) insertedly

slides.

Each cylinder (234) is mounted with suction/exhaust means having suction/exhaust valves (256, 258) and ignition means having an ignition plug (260).

In case of a diesel engine, the cylinder (234) is disposed with suction/exhaust means and fuel injection means. The output shaft (238) is rotatably supported at the cam case (232) by a bearing (262).

The piston (236) is concaved at its bottom portion and both sides of the bottom portion are formed with flanges (236a, 236b). The rollers (244, 245) are rotatably mounted between the flanges (136a, 136b) by pins (264, 264). The piston (236) is

centrally and insertedly disposed with the ball rod (246). Preferably, the rollers (244,

245) are rotatably coupled by roller bearings to be externally inserted to the pins (264,

264). The cam (240) is formed with four cam crests, each spaced at 90 degrees apart,

and the number of cam crests may vary and the shapes thereof may be variably

manufactured. The number of cylinders may also vary.

The ball rod (246) is formed at a distal end thereof with a head part (246a)

hitched by being inserted into the piston (236), and is also formed at the other distal

end thereof with a rod formed with a ball part (246b) slidably hitched by being inserted

into the track groove (252a). The ball part (246b) is protruded far lower than a lower

peripheral surface of the rollers (244, 245).

Referring to FIG. 12, the traces of the track surfaces (248, 250) where the

rollers (244, 245) externally contact, ride and move along, and traces of the track

grooves (252a) where the ball part (246b) of the ball rod (246) rides and slides, are not alike but may be overlapped at some regions thereof. The track surfaces (248, 250) and the track grooves (252a) become dissimilar according to the cam curvatures, sizes of the rollers and ball rod, and distances from the center of the output shaft to the bottom dead center of the piston and from the center of the output shaft to the upper dead center of the piston. The operation of the cam and hump track type engine thus described according

to the third embodiment of the present invention will now be explained.

Referring to FIG. 10, when the piston (236) at an upper side is referred to as a

first piston, other pistons are referred to as a second, a third and a fourth piston in

counterclockwise order. The pistons are operated in the same manner as shown in

FIG. 7.

When the output shaft (238) is rotated to rotate the cam (240) in the

counterclockwise direction, the piston (236) is lowered along the cam crest by the

rollers (244, 245) for tightly rolling along the track surface (248, 250) of the cam (240)

and by the ball part (246b) for riding along the track groove (252a) of the hump track

part (252), as in FIG. 10, to open the suction valve (256), thus allowing air-fuel mixture

to be sucked into the cylinder (234) and reach the bottom dead center of FIG. 13. The

cam (240) is further rotated to raise the piston (236) and to compress the air-fuel

mixture in the cylinder (234), and ignition is effected by the ignition plug (260) at the

upper dead center to explode and expand.

The piston (236) is again lowered to arrive at the bottom dead center, and rises again to allow the exhaust gas in the cylinder (234) to be exhausted via the exhaust valve (258), and is positioned to a state as shown in FIG.10. While the cam (240) is rotated one time as mentioned above, four pistons (236) make two reciprocations to effect a four-stroke cycle of suction, compression, expansion and exhaust. In the cam and hump track type engine according to the third embodiment of

the present invention, one explosion occurs in the respective four cylinders while the

cam (240) is rotated one time to enable to lighten the weight of the engine and obtain

an enhanced output. Furthermore, the cam (240) is rotated one time against two times of

reciprocation for each piston (236) such that the rotation of the output shaft (238) is

reduced, thereby restraining the output rotation number and generation of heat and

vibrations and thereby increasing energy conversion efficiency.

Referring now to FIGS. 14 and 15, a cam and hump track type engine

according to the fourth embodiment of the present invention includes a casing (330)

radially and integrally disposed with four cylinders (334) at every 90 degrees about a

cam case (332), and a piston (336) reciprocating within the cylinders (334) A cam

(340) is fixed by a key (342) on an output shaft (338) disposed at a center of the cam case (332). A main roller (344) externally contacting a track surface (peripheral surface: 340a) of the cam (340) is rotatably mounted at the piston (336). An auxiliary roller (346) is disposed at the piston (336) for pulling down the piston (336) and for preventing the main roller (344) from being derailed from a track surface (peripheral surface) of the cam (340).

The cam (340) is formed with a hump track (350) formed with track grooves (350a, 350b) where the auxiliary roller (346) slidably rolls, and the main roller (344) and the auxiliary roller (346) are disposed on the same axis. The cam (340) is

centrally formed with a projection to form a hump track (350), and the projection is

formed at both axial sides thereof with a track surface (340a) externally contacted by

the main roller (344). The projection is formed at both lateral surfaces thereof with

the track grooves (350a, 350b) along where the auxiliary roller (346) slidably rolls.

Thus, the fourth embodiment of the present invention is respectively disposed with the

main roller (344) and the auxiliary roller (346). The hump track part (350) may be

separated from the cam (340) to be fixed to the output shaft (338) by a key, or may be

fixed to a lateral surface of the cam (340) by a bolt. Each cylinder (334) is mounted with suction/exhaust means having

suction/ exhaust valves (356, 358) and ignition means having an ignition plug (360).

The cylinder (334) in a diesel engine is disposed with suction/exhaust means and fuel

injection means. The output shaft (338) is rotatably supported at the cam case (332)

by a bearing (362). The piston (336) having a concaved bottom portion and is formed with flanges

(336a, 336b) at both sides of the bottom portion, and the flanges (336a, 336b) are respectively disposed with pins (364). Both ends of the pins (364) are rotatably mounted with the main roller (344) and the auxiliary roller (346). Preferably, the main roller (344) and the auxiliary roller (346) are rotatably coupled by a roller bearing externally inserted to the pins (364). The cam (340) is formed with four cam crests, each spaced at 90 degrees apart,

and the number of cam crests may vary and the shapes thereof may be variably

manufactured. The number of cylinders may also vary.

The operation of the cam and hump track type engine thus described according

to the fourth embodiment of the present invention will now be explained.

Referring to FIG. 14, when the piston (336) at an upper side is reffered to as a

first piston, other pistons are referred to as a second, a third and a fourth piston in the

counterclockwise direction. The pistons are operated in the same manner as shown in

FIG 7. When the output shaft (338) is- rotated to rotate the cam (340) and the hump

track part (350) in the counterclockwise direction, the piston (336) is lowered along the

cam crest by the main roller (344) tightly rolling along the track surface (340a) of the

cam (340) and the auxiliary roller (346) riding along the track grooves (350a, 350b) of

the hump track part (350), as in FIG. 14, to open the suction valve (356), thus allowing

air-fuel mixture to be sucked into the cylinder (334) and reach the bottom dead center of FIG. 16. The cam (340) and the hump track part (350) are further rotated to raise

the piston (336) and to compress the air-fuel mixture in the cylinder (334), and ignition is effected by the ignition plug (360) at the upper dead center to explode and expand.

The piston (336) is again lowered to arrive at the bottom dead center, and rises again to allow the exhaust gas in the cylinder (334) to be exhausted via the exhaust valve (358), and is positioned to a state in Fig. 14. While the cam (340) and the

hump track part (350) are rotated one time as mentioned above, four pistons (336)

make two reciprocations to effect a four-stroke cycle of suction, compression,

expansion and exhaust. In the cam and hump track type engine according to the fourth embodiment of

cam (340) and the hump track part (350) are rotated one time to enable to lighten the

weight of the engine and obtain an enhanced yield.

Furthermore, the cam (340) and the hump track part (350) are rotated one time

with respect to two times of reciprocation for each piston (336) such that the output

shaft (338) is decreased in rotation thereof, thereby restraining the output rotation

number and generation of heat and vibrations, and increasing the energy conversion efficiency.

Referring now to FIGS. 17 and 18, a cam and hump track type engine according to the fifth embodiment of the present invention includes a casing (430) radially and integrally disposed with four cylinders (434) at .every 90 degrees about a hump track case (432) and a piston (436) reciprocating within the cylinder (434).

The engine further includes first and second hump parts (440, 442) each spaced a predetermined distance apart on an output shaft (438) centrally disposed at the hump track case (432) and formed at an inner surface thereof with track grooves (440a, 442a), a first roller (446) rotatably coupled at a lower end of the piston (436) for

raising and lowering the piston by slidably rolling along the track groove (440a) of the

first hump track part (440), and a second roller (448) rotatably coupled at the other

lower end of the piston (436) for rasing and lowering the piston by slidably rolling

along the track groove (442a) of the second hump track part (442).

The first and second rollers (446, 448) are coupled to both ends of a pin (454),

the pin (454) is inserted into a connecting member (452), and the connecting member

(452) is fixed by a fixation pin (450) by being inserted into a lower side of the piston

(436). Preferably, the first and second rollers (446, 448) are rotatably coupled by a

roller bearing to be externally inserted to the pin (454).

Meanwhile, the piston (436) may be extensively formed thereunder with a

flange, and the flange may be coupled with the first and second rollers by a pin. The

output shaft (438) is formed with hitching jaws (438a, 438b) where the first and

second hump track parts (440, 442) are inserted and hitched, and the first and second

hump track parts (440, 442) inserted into the output shaft (438) are tightly fixed by a

key (456). The output shaft (438) is rotatably supported by the bearing (458) at the hump track case (432).

The first and second hump track parts (440, 442) are plates tightly coupled by a coupling member (462) comprising a bolt and a nut with a spacer (460) being interposed therebetween. Each cylinder (434) is mounted with suction/exhaust means having

suction/exhaust valves (464, 466) and ignition means having an ignition plug (468).

injection means. The track grooves (440a, 442a) of the first and second hump track parts (440,

442) are alternatively formed with four crests and valleys each spaced at every 90

degrees apart. The number of crests and valleys may vary, and the shapes thereof

may be variably manufactured. The number of cylinders may also vary. The shapes

of the track grooves vary according to the size of the rollers, distances from the center

of the output shaft to a bottom dead center of the piston and from the center of the

output shaft to an upper dead center of the piston.

The operation of the cam and hump track type engine thus described according

to the fifth embodiment of the present invention will now be explained.

When the piston (436) at an upper side in FIG. 17 is referred to as a first piston,

other pistons are referred to as a second, a third and a fourth piston in the

FIG. 7.

When the output shaft (438) is rotated to rotate the first and second hump track parts (440, 442) in the counterclockwise direction, the piston (36) is lowered along the cam crest by the first and second rollers (446,448) rolling along the track grooves (440a, 442a) of the first and second hump track parts (440, 442), as in FIG. 17, to open

the suction valve (464), thus allowing air-fuel mixture to be sucked into the cylinder

(434) and reach the bottom dead center of FIG 19. The hump track parts (440, 442)

are further rotated to raise the piston (436) and to compress the air-fuel mixture of

gasoline and air in the cylinder (434), and the air-fuel mixture is ignited by the ignition

plug (468) at the upper dead center of the piston. Then, the air-fuel mixture is

exploded and expanded. The piston (436) is again lowered to arrive at the bottom

dead center, and rises again to allow the exhaust gas in the cylinder (434) to be

exhausted via the exhaust valve (466) as depicted in FIG. 17. While the hump track

parts (440, 442) are rotated one time as mentioned above, four pistons (436) make two

exhaust.

In the cam and hump track type engine according to the fifth embodiment of

hump track parts (440, 442) are rotated one time to enable to lighten the weight of the engine and obtain an enhanced output. Furthermore, the hump track parts (440, 442) are rotated one time with respect to two times of reciprocation for each piston (436) such that the output shaft (438) is decreased in rotation thereof, thereby restraining the output rotation number and generation of heat and vibrations, and increasing the energy conversion efficiency. The foregoing description of the preferred embodiments of the present

invention has been presented for the purpose of illustration and description. It is not

intended to be exhaustive or to limit the invention to the precise form disclosed, and

modifications and variations are possible in light of the above teachings or may be

acquired from practice of the invention. It is intended that the scope of the invention

be defined by the claims appended hereto, and their equivalents.

As apparent from the foregoing, there is an advantage in the cam and hump

track type engine thus described according to the embodiments of the present invention

in that the cam and/or hump track parts are rotated one time while one time of

explosion occurs at each cylinder, enabling the engine to be compact and light-weight

for an enhanced yield.

There is another advantage in that the cam and/or the hump track parts are

rotated once while each piston reciprocates twice to thereby enable to reduce the

revolution of the output shaft and to restrain the output rotation number and generation of heat and vibrations for increased energy conversion efficiency.

Claims

WHAT IS CLAIMED IS:

1. A cam and hump track type engine comprising: a casing radially disposed with a plurality of cylinders about a cam case, pistons reciprocating within said cylinders, a cam mounted on an output shaft disposed at a center of said cam case, a main roller externally contacting said cam and rotatably mounted at each

said piston, and auxiliary rollers disposed at said piston for lowering said piston and for

preventing said main roller from being derailed from a peripheral surface of said cam, wherein said output shaft mounted with said cam has a hump track part formed with a track groove along where said auxiliary rollers ride.

2. The engine as defined in claim 1, wherein said piston is centrally concaved at a bottom portion thereof and both sides of said bottom portion are formed with flanges, said main roller is rotatably mounted between said flanges by a first pin, said auxiliary rollers are rotatably mounted at a lower portion of said flanges by second pins, and said cam is provided at both sides thereof with said hump track part, and said track grooves are formed at an inner surface of said hump track part.

3. The engine as defined in claim 1, wherein said piston is centrally concaved at a

bottom portion thereof and both sides of said bottom portion are formed with flanges, said main roller is rotatably mounted between said flanges by a first pin, said auxiliary rollers are rotatably mounted at a lower portion of said flanges

by second pins, and said cam is provided at both sides thereof with said hump track part and said

track grooves are formed at an external surface of said hump track part.

4. A cam and hump track type engine comprising: a casing radially disposed with a plurality of cylinders about a cam case, pistons reciprocating within said cylinders, a cam disposed on an output shaft disposed at a center of said cam case, two rollers externally contacting said cam and rotatably mounted at each said

piston, and a ball rod disposed at said piston for lowering said piston and for preventing said rollers from being derailed from a peripheral surface of said cam, wherein said cam is formed at both sides thereof with track surfaces where said two rollers respectively externally contact and roll along, and said cam is centrally formed with a hump track part having a track groove into which a ball part of said ball rod is slidingly inserted.

5. A cam and hump track type engine comprising: a casing radially disposed with a plurality of cylinders about a cam case, pistons reciprocating within said cylinders, a cam provided on an output shaft disposed at a center of said cam case, a main roller externally contacting said cam and rotatably mounted at each

preventing said main roller from being derailed from a peripheral surface of said cam, wherein said cam is provided with a hump track part formed with a track

groove along where said auxiliary rollers ride and roll, and said main roller and said auxiliary rollers are arranged along the same axis.

6. The engine as defined in claim 5, wherein said cam is centrally formed with a projection to form a hump track, a track surface externally contacting said main roller is formed at both sides of said projection along a direction of said output shaft, and said projection is formed at both lateral surfaces thereof with said track grooves along where said auxiliary rollers ride and roll.

7. A cam and hump track type engine comprising: a casing radially disposed with a plurality of cylinders about a hump track case, pistons reciprocating within said cylinders, a first and a second hump track part each spaced a predetermined distance

and second hump track part each formed at an inner surface thereof with a track groove, a first roller coupled to a lower portion of said piston for riding and rolling

along said track groove of said first hump track part so as to raise and lower the piston,

said piston.