WO2006083135A1

WO2006083135A1 - Assembly of piston and connecting rod

Info

Publication number: WO2006083135A1
Application number: PCT/KR2006/000412
Authority: WO
Inventors: Peter Hans Kolb
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-02-04
Filing date: 2006-02-04
Publication date: 2006-08-10
Anticipated expiration: 2007-08-04
Also published as: KR20060089679A; KR100735091B1

Abstract

The present invention is related to a piston and connecting rod assembly having a structure that can reduce the height of engine, increase a torque, and reduce a friction between cylinder and piston. The piston and connecting rod assembly according to the present invention comprises a piston block in which a spherical space is formed; a spherical body received rotatably in the spherical space of the piston block; and a connecting rod coupled to the spherical body through a first opening formed at one surface of the piston block to be communicated with the spherical space. The piston and connecting rod assembly according to the present invention further comprises an upper cover covering the spherical body exposed through a second opening, formed on an opposite surface to the surface of the piston block on which the first opening is formed, and communicated with the spherical space. The spherical body consists of upper and lower semispherical bodies, and the connecting rod is coupled to the lower semispherical body through a coupling means penetrating the through hole formed at a lower surface of the lower semispherical body. The connecting rod comprises a semi ring-shaped bearing block formed on an opposite portion of the connecting rod to a portion coupled to the spherical body, a ring shaped-bearing section mounted to an inner surface of the semi ring-shaped bearing block and a band fixed to the connecting rod in the state that the band is wrapped around the outer circumference of the bearing section.

Description

ASSEMBLY OF PISTON AND CONNECTING ROD

TECHNICAL FIELD

The present invention is related to a piston and connecting rod assembly, and particularly to a piston and connecting rod assembly having a structure that can reduce the height of engine, increase a torque, and reduce a friction between cylinder and piston.

BACKGROUND ART

hi general, a piston type compressor (hereinafter referred to as "engine") such as an engine for a vehicle is an apparatus for converting thermal energy into mechanical energy, and uses energy generated when combustion gas from combusting and exploding air-fuel mixture in a cylinder is expanded.

The engine as described above comprises a piston, a connecting rod and a crank shaft for converting thermal energy into mechanical energy. The piston of engine is reciprocated in the cylinder by an expansion force of combustion gas, and transmits the gas pressure of high temperature and high pressure to the connecting rod.

The connecting rod to connect the piston and the crank shaft is the member for converting a linear motion of the piston into a rotational motion, and transmitting the rotational motion to the crank shaft. The crank shaft transmits the transmitted rotational force to a power transmission means.

A typical example of the piston, the connecting rod, and the crank shaft having the structure and function as described above is shown in FIG. 1.

A piston 1 reciprocated in the cylinder has a plurality of piston rings 2 mounted on its outer circumference surface, and so the piston rings seal the cylinder, and scrape some oil on an inner circumference surface of the cylinder.

The piston 1 is connected to an upper end of a connecting rod 4 through a piston pin 3, and a connecting rod cap 5 is coupled with a lower end of the connecting rod 4. On the other hand, a connecting rod bearing (not shown) is located in the connecting rod cap 5 to connect the connecting rod to a crank shaft 6.

In the piston and connecting rod assembly as shown in FIG. 1, it is difficult to insert the circular piston ring 2 into a groove formed on the outer circumference of the piston 1. In order to solve the above problem, the piston ring is placed in the groove after a portion of the piston ring 2 is cut out. Accordingly, the piston ring 2 a portion of which is cut out cannot perform well its function. As a result, there are problems that oil is entered and burned in a combustion room, or combustion gas leaks out of the combustion room.

On the other hand, the length of the connecting rod 4 is a distance between the center-line of the piston pin coupled thereto and the center- line of the crank shaft 6, which is approximately 1.5 to 2.3 times a normal piston stroke.

In case the length of the connecting rod 4 is extended, lateral pressure of the piston 1 applied to the cylinder wall is reduced, and abrasion of the cylinder is decreased. This structure also has problems that such engine is disadvantageous in the strength or weight, and the engine's height is increased.

In the piston and connecting rod assembly as shown in FIG. 1 , however, the piston 1 and the connecting rod 4 are coupled to each other through the piston pin 3, and the length of the connecting rod 4 should be lengthened, and thus the height of the engine cannot but be increased. Also, the assembly has the structure that a low end portion of the connecting rod 4 and the connecting rod cap 5 are coupled at both sides, and a turning radius of the connecting rod 4 coupled to the crank shaft 6 is increased, and thus the size of the engine block also should be increased. Consequently, the weight of the connecting rod 4 having an extended length and the engine block with increased size is increased, resulting in a problem that the fuel consumption is rapidly increased.

DISCLOSURE OF INVENTION The present invention is to solve the problems of the conventional piston and connecting rod assembly as described above. Thus, an object of the present invention is to provide a piston and connecting rod assembly having a structure that can reduce the height of engine, increase a torque, and reduce a friction between cylinder and piston.

For achieving the above object, the piston and connecting rod assembly comprises a piston block in which a spherical space is formed; a spherical body received rotatably in the spherical space of the piston block; and a connecting rod coupled to the spherical body through a first opening formed at one surface of the piston block to be communicated with the spherical space.

The piston block consists of an upper block and a lower block, having spherical recesses on one surface thereof, and the recesses form the spherical space.

On the other hand, the piston and connecting rod assembly according to the present invention further comprises an upper cover covering the spherical body exposed through a second opening, formed on an opposite surface to the surface of the piston block on which the first opening is formed, and communicated with the spherical space, and the surface of the cover contacting with the spherical body is formed in the spherical shape to correspond to the surface of the spherical body.

The piston and connecting rod further comprises a first piston ring mounted between a protrusion structure formed on an outer circumference surface of the piston block and the upper cover, and it is preferable that the first ring is a compression ring which is spirally wound around the piston block several times in a spiral shape.

The piston and connecting rod assembly further comprises a lower cover covering the surface of the piston block on which the first opening is formed so that the connecting rod can penetrate the lower cover, and further comprises a second piston ring mounted between the protrusion structure formed on an outer circumference surface of the piston block and the lower cover. The second piston ring performs a function of an oil scraper ring, and the protrusion structure can be a third piston ring made of carbon fiber and wounded around the piston block.

On the other hand, the spherical body consists of upper and lower hollow semispherical bodies, and the connecting rod is coupled to the lower semispherical body through a coupling means penetrating the through hole formed at a lower surface of the lower semispherical body. The upper semispherical body and the lower semispherical body are coupled to each other through a hook piece and a protrusion piece formed inside, respectively. The spherical body has a plurality of through holes formed on an outer surface to discharge oil supplied through the penetrating flow passage formed in the coupling means and the oil flow passage formed in the connecting rod.

The piston and connecting rod assembly further comprises a ring shaped-bearing section mounted to an inner surface of the semi ring-shaped bearing block formed on an opposite portion of the connecting rod to a portion coupled to the spherical body, the bearing section consists of a first semi ring-shaped bearing and a second semi ring-shaped bearing.

On the other hand, a portion of circumference surface of the bearing section is a flat surface, and the bearing block of the connecting rod has a flat surface portion to correspond to the flat surface of the bearing section.

The piston and connecting rod assembly further comprises a band fixed to the connecting rod in the state that the band is wrapped around the outer circumference of the bearing section, the band is coupled such that the band is placed in the groove formed on an outer circumference of the connecting rod. hi particular, both end portions of the band are coupled to the connecting rod by a coupling means passing through the connecting rod.

EFFECT OFTHE INVENTION

Compared with the conventional piston and connecting rod assembly, the piston and connecting rod assembly according to the present invention can have the following advantages.

1. hi order to mount the piston rings on an outer circumference surface of the piston, that is, outer circumference surfaces of the upper block and the lower block, there is no need to cut out a portion of each piston ring. That is, in a state that each piston ring corresponds to each block, the piston ring is pushed along an outer circumference surface of the block so that each piston can be mounted to each block. Accordingly, an increased sealing effect can be obtained by employing the piston rings (compression rings). Also, exhaust pollutants can be reduced by preventing leakage of combustion gas to an outside through the cut portion in the conventional piston ring, and oil burning. 2. The distance between an upper side surface of the piston and the center line of the crank shaft (i.e., the central line of the bearing section) is remarkably decreased. If a location of the crank shaft and a location of the cylinder in the present assembly are same as in the conventional piston and connecting rod assembly, the volume of combustion room of the cylinder can be increased, whereby the amount of exhaust gas is increased, and the height of engine can be reduced significantly.

3. In addition, the present invention is applicable to the conventional engine block without much time and expense. In this case, the follow advantages can be obtained: a) The conventional gasoline engine can be converted into a diesel engine (or bio diesel engine) with an increased compression ratio. b) The present invention can be used in a lower RPM level, and so fuel consumption is decreased, and an optimum control against exhaust gas can be achieved.

4. The engine can be smaller by employing the present invention. Thus, the present invention is ideally applicable to a hybrid vehicle which has gained attention as new conceptual pollution- free vehicle. That is, in the present invention, the size of engine can be reduced remarkably, and so a marginal space can be secured and the weight of engine can be reduced. Also, in the present invention, the secured space can be used for disposing an electrical motor and related controller.

5. If the piston and connecting rod assembly according to the present invention is applied to the cylinder and crank shaft of the diesel engine having a cylinder with a relatively huge volume, the compression ratio is increased, and so the effect to enhance the efficiency of engine can be expected. 6. Further, due to the third piston ring mounted to an outer circumference surface of the upper and lower blocks of the piston, and made of carbon fiber or porous aluminum, the friction between an outer surface of the piston and an inner surface of the cylinder can be reduced, damage on the both members can be prevented, and noise is remarkably reduced by eliminating wobbling of the piston. Also, it is possible to optimally control free rotation of the piston and prevent wear of the piston. Thus, the expected life span of the piston, that is, engine, can be extended.

7. Compared with the conventional piston, the piston according to the present invention to which the upper cover made of stainless steel is fixed enables the engine to do rapid warming-up, whereby exhaust gas generated at a lower temperature state can be reduced.

BRIEF DESCRIPTION OF DRAWINGS

The above and other objects, features and advantages of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of the conventional piston and connecting rod assembly;

FIG. 2 is a sectional perspective view of the piston and connecting rod assembly according to the present invention for showing structural members;

FIG. 3 is a cross-sectional view of the state that the structural members are assembled;

FIG. 4 is a perspective view of the piston and connecting rod assembly according to the present invention; and FIG. 5 is a partially sectional view of the piston and connecting rod assembly according to the present invention having another structure.

BEST MODE FORCARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention is applicable to all piston types of combustion engines and compressors. However, the following descriptions are focused on only the piston and connecting rod, and crank shaft which are the gists of the present invention. FIG. 2 is a sectional perspective view of the piston and connecting rod assembly according to the present invention for showing structural members. FIG 3 is a cross- sectional view of the state that the structural members are assembled. The piston and a connecting rod assembly (hereinafter, referred to as "assembly" for convenience¹ sake) consists of a piston 100 moving upward and downward in a cylinder, and a connecting rod 200 whose upper side and lower side are coupled to the piston 100 and a crank shaft (not shown), respectively.

The structure of each member constituting the piston 100 and connecting rod 200 is described below.

Piston 100

The piston 100 comprises an upper block 20, a lower block 30 and a cover 10 coupled to an upper side of the upper block 20.

Each of the upper block 20 and the lower block 30 is a cylindrical member, and each of hemispherical recesses 21, 31 is formed in the upper block and lower block. On the other hand, a lower end and an upper end of each of the upper block 20 and the lower block 30 are open. Thus, a spherical recess formed by coupling the upper block 20 to the lower block 20 is communicated with the exterior through the open upper and lower ends. A plurality of through holes 22 and 32 are formed on outer portions of the upper block 20 and the lower block 30, and a plurality of through holes 12 are also formed on an outer portion of the cover 10 coupled to the upper block 30. Here, the cover 10 is made of stainless steel having excellent corrosion resistance.

On the other hand, a rim 23 having a certain width is formed on an outer circumference surface of an upper portion of the upper block 20, and another rim 33 having a certain width is formed on the entire outer circumference surface of a lower end portion of the upper block 30.

The piston 100 further comprises a hollow spherical body 40. This spherical body 40 consists of an upper semispherical body 41 and a lower semispherical body 42 having a size sufficient to be received in the semispherical recesses 21 and 31 formed on the upper block 20 and the lower block 30, respectively. A plurality of through holes 41-1 and 42-1 are formed on the upper semispherical body 41 and the lower semispherical body 42, respectively. In particular, a through hole 42-3 is formed on a central portion of a lower end of the lower semispherical body 42 for coupling the spherical body to a connecting rod 200 described below.

Here, as shown in FIG. 3, a hook piece 41-2 is formed on an inner surface of a lower end of the upper semispherical body 41 along the entire circumference surface, and a protrusion piece 42-2 is formed on an inner surface of an upper end of the lower semispherical body 42 along the entire circumference surface. On the other hand, the piston 100 comprises a first piston ring 51 mounted to an outer circumference surface of the upper block 20, a second piston ring 52 mounted to an outer circumference surface of the lower block 30, and a third piston ring 60 mounted to a border section between the upper block 20 and the lower block 30. The third piston ring 60 is made of carbon fiber or porous aluminum having excellent abrasion resistance, corrosion resistance and malleability.

The process for mounting the piston rings 51, 52 and 60 will be described later.

Connecting rod 200 The connecting rod 200 coupled to the piston 100 via an upper end and coupled to a crank shaft (not shown) through a lower end comprises a rod 210 with a certain length, a bearing section 220, and a steel band 230.

A coupling cavity 211 is formed at an upper end portion of the rod 210. A spiral is formed on an inner circumference surface of the coupling cavity. And, a semi ring- shaped bearing block 212 is integrated with the rod at a low portion of the rod. Grooves

213 with a certain depth are formed on outer surfaces of both sides of the bearing block

212, and a through hole 214 traversing the bearing block is formed at a border section between the rod 210 and the bearing block 212.

The bearing section 220 consists of semi ring-shaped first and second bearings 221 and 222 placed in the semi ring-shaped bearing block 212. The first and second bearings

221 and 222 are coupled to each other by the steel band 230 to form the ring-shaped bearing section. This bearing section 220 is mounted to an outer circumference surface of the crank shaft (not shown) to maintain smooth rotation of the crank shaft.

The steel band 230 is made of metal and has a curved shape, but both ends portions thereof are formed in the plate shape, having each coupling hole 231.

The process for coupling the piston 100 to the connecting rod 200 as constructed above, and function of each member are described with reference to the drawings.

First, the ring-shaped bearing section 220 is formed by enabling the semi ring- shaped first and second bearings 221 and 222 constituting the connecting rod 220 to correspond to each other. Then, the bearing section 220 is placed in the bearing block 212 formed at a lower side of the rod 210.

In the state that the steel band 230 wraps the lower bearing (the second bearing 222 in the drawing), both side portions of the steel band 230 are received in the grooves 213 formed on outer circumference surfaces of both sides of the bearing block 212. In the state, a bolt Bl of a coupling means is passed through the coupling holes 231 formed at both ends portions 230 and the through hole 214 formed at the bearing block 212, thereby completing assembling of the connecting rod 200.

Here, although FIG. 2 and FIG. 3 show the state that both plate-shaped end portions (on which the coupling holes 231 are formed) of the steel band 230 are placed on an outer side of the bearing block 212, but the locations of the plate shaped end portions of the steel band are not limited thereto.

That is, a space dividing the through hole 214 is formed at the bearing block 212, and an elastic member (on which a through hole communicated with the through holes 214 is formed) is placed in the space. Then, both plate-shaped end portions of the steel band 230 are made to correspond to both side surfaces of the elastic member, and the coupling bolt Bl is passed through the through holes of the steel band and the elastic member so that the two members can be coupled to each other.

In this structure, the diameter of the steel band can be adjusted by elasticity of the elastic member so that the steel band 230 can fix securely the first and second bearings 212 and 222 to the bearing block 212 even when the size of the first and second bearings 212 and 222 (that is, the diameter of the bearing section 200) is changed.

On the other hand, the first piston ring 51 is inserted on an outer circumference surface of the upper block 20, and then placed on the rim 23 of the upper block. The second piston ring 52 is also inserted on an outer circumference surface of the second block 30, and then placed on the rim 33 of the lower block.

Accordingly, when the first and second piston rings 51 and 52 are mounted, the first and second piston rings 51 and 52 can be pushed and moved along outer circumference surfaces of the upper block 20 and the lower block 30 with no need to cut out a portion of each piston ring, thereby effectively maintaining the sealing function of the first and second piston rings 51 and 52.

In the state, the lower semispherical body 42 is placed in the semispherical recess

31 of the lower block 30 of the piston 100, and then the coupling cavity 211 formed at the upper end of the rod 210 of the connecting rod 200 is placed to correspond to the through hole 42-3 formed at a central portion of lower end of the semispherical recess 31. In this state, a washer 43 is placed around the through hole 42-3, and a bolt 44 is passed through the through hole 42-3 and screwed into the coupling cavity 211 formed at the upper end of the rod 210. Then, the upper semispherical body 41 is coupled to the lower semispherical body 42.

In general, two compression rings 2 are mounted on an outer circumference surface of the piston 1 to maintain the airtight state and transmit heat of the piston to a cylinder block when air- fuel mixture is compressed and expanded, as shown in FIG. 1.

In the present invention, one multi-spiral shaped compression ring as the first piston ring 51 is mounted to perform the function of two compression rings.

Then, the upper block 20 is fixed to the lower block 30 on which the spherical body 40 is fixed, in the semispherical recess 31.

That is, as shown in the drawings, in the state that the cover 10 is placed on the upper block 20, and the cover 10, the upper block 20 and the lower block 30 correspond to each other, the bolt B is passed through the through holes 12, 22 and 32 corresponding to each other, to couple to the nut N, Thus, the cover 10, the upper block 20 and the lower block 30 can be integrated together.

Here, the means for coupling the upper block 20 to the lower block 30 is not limited to the bolts B and the nuts N. That is, various coupling means such as rivet and the like can be used for coupling the upper block 20 to the lower block 30.

A groove 111 having a certain width is formed on an outer circumference surface of a border section between the upper block 20 and the lower block 30 coupled to each other by the rims 23 and 33 formed on outer circumference surfaces of the upper block 20 and the lower block 30. The third piston ring 60 as mentioned above is received in this groove 111, to complete the process for assembling the piston 100 and the connecting rod 200 shown in FIG. 3.

Detailed functional characteristics of the piston and connecting rod assembly through the above processes are as follows.

1. Function for supplying oil

The connecting rod 200 which connects the piston 200 performing a linear motion and the crank shaft performing a rotational motion performs simultaneously an up-down motion and a rotational motion. Thus, the spherical body 40 fixed to an upper end of the connecting rod 200 is rotationally and regularly moved in a spherical space 21 and 31 formed by coupling the upper block 20 to the lower block 30. Then, a friction is generated between an outer surface of the spherical body 40 and an inner surface of the upper and lower blocks 20 and 30. This friction makes continuous movement of the spherical body 40 difficult.

In order to ensure smooth motion of the spherical body 40 in the upper block 20 and the lower block 30, the present invention adopts the structure that lubricating oil stored in the spherical body 40 can be discharged to the outside.

That is, a plurality of through holes 41-1 and 42-1 are formed on the upper semispherical body 41 and the lower semispherical body 42 constituting the spherical body

40, and so oil in the rotating spherical body 40 is discharged to the outside through the through holes 41-1 and 42-1. Discharged oil is flowed between an outer circumference surface of the spherical body 40 and an inner circumference surface of the upper and lower blocks 20 and 30 to reduce a friction between two members and make a smooth motion possible.

On the other hand, in order to supply oil to an inner space of the spherical body 40 formed by the upper semispherical body 41 and the lower semispherical body 42 coupled to each other, an oil flow passage 240 which is communicated in fluid with the coupling cavity 211 is formed in the rod 210 of the connecting rod 200, and an oil supplying port 240-1 communicated in fluid with the oil flow passage 240 is formed on one side of the rod 210.

Also, a penetrating flow passage 44-1 is formed in the bolt 44 coupling the lower semispherical body 42 to the rod 210. In this structure, if oil stored in the spherical body 40 is reduced to an optimum amount or less, once oil is poured through the oil supplying port 240-1 of the rod 210, oil is flowed into an inner space of the spherical body 40 through the oil flow passage 240 in the rod 210 and the penetrating flow passage 44-1 of the bolt 44.

In particular, the oil flow passage 240 formed in the rod 210 can be extended to the bearing block 212, and so supplied oil can reduce a friction between the crank shaft and the bearing section 220.

2. Function for preventing movement of the bearing section 200

In the present invention, as shown in FIG. 3, inner surfaces of both side end portions of the bearing block 212, and outer surfaces 221A and 222A of both side end portions of the first and second bearings 221 and 222 corresponding to the inner surfaces of both side end portions of the bearing block are formed in flat surface, not curved surface.

Due to this structure, even though the crank shaft is rotated in the bearing section

200, the bearing section 200 is not rotated to the bearing block 212. Consequently, the rotation center of the bearing section 200 is not deviated from an originally set location.

3. Function for preventing separation of the upper semispherical body 41 and the lower semispherical body 42

As described above, the hook piece 41-2 is formed on an inner surface of a lower end of the upper semispherical body 41 along the entire circumference surface, and the protrusion piece 42-2 is formed on an inner surface of upper end of the lower semispherical body 42 along the entire circumference surface.

Accordingly, when the upper semispherical body 41 and the lower semispherical body 42 are coupled to each other, the hook piece 41-2 formed on an inner surface of a lower end of the upper semispherical body 41 is combined with the protrusion piece 42-2 formed on an inner surface of an upper end of the lower semispherical body 42. Thus, perfect combination between the upper semispherical body 41 and the lower semispherical body 42 can be maintained although an external force (action force generated by the motion of the spherical body 40) is applied to the spherical body 40.

In addition to the above structure, the upper and lower semispherical bodies can be designed such that the outer diameter of some of a lower end portion of the upper semispherical body 41 is the same as the inner diameter of an upper end portion of the lower semispherical body 42. If so, when the upper semispherical body 41 and the lower semispherical body 42 are coupled to each other, some of lower end portion of the upper semispherical body 41 can be received in the lower semispherical body 42 to induce coupling of two semispherical bodies 41 and 42.

4. Function of each piston ring mounted to an outer circumference surface of the piston 100

As shown in FIG. 3, the third piston ring 60 is mounted on an outer circumference surface of a border section between the upper block 20 and the lower block 30 coupled to each other. The third piston ring 60 is made of carbon fiber, and remarkably reduces the friction force between an inner surface of the cylinder and an outer surface of the piston 100 (that is, the upper block 20 and the lower block) performing the up-and-down motion.

Also, the first piston ring 51 mounted on an outer circumference surface of the upper block 20 is a single multi-spiral shaped compression ring and performs the function of two compression rings. In addition, the second piston ring 52 mounted on an outer circumference surface of the lower block 30 scrapes oil existing on an inner wall of the cylinder. Accordingly, it is possible to prevent burning of residual oil existing on the inner wall of the cylinder.

5. Material used for manufacturing the cover 10 The cover 10 to which the heat and pressure of gas exploded in the cylinder are primarily transmitted should have corrosion resistance superior to other members. Accordingly, the cover 10 made of stainless steel is used in the present invention. On the other hand, in a case that the upper block 20 in which the upper semispherical body 41 of the spherical body 40 is received is made of stainless steel, and an upper side of the upper block is closed, the upper block 20 can perform the function of the cover, and so there is no need to couple the separate cover 10 to the upper block 20.

FIG. 5 is a partial sectional view of the piston and connecting rod assembly according to the present invention having another structure. For convenience' sake, the piston and only a portion of the connecting rod are shown in the drawing. On the other hand, the entire structure of the piston and connecting rod assembly shown in FIG. 5 is the same as that of the piston and connecting rod assembly shown in FIG. 2 to FIG. 4, and so the same descriptions are omitted and only characteristic parts will be described below.

The structural characteristics of the piston and connecting rod assembly shown in FIG. 5 lies in that an opening section formed at an upper end of an upper block 2OA is larger than that formed at a lower end of a lower block 30A, and the thickness of the upper block 2OA is less than that of the lower block 30A. If the spherical body 40 is received in an inner space formed by the upper block 2OA and the lower block 30A having the structure as described above, a portion of the upper semispherical body 41 is protruded on the surface of the upper block 2OA.

In a case that the piston and connecting rod assembly having the above structure is applied to the engine block in which the conventional piston and connecting rod assembly shown in FIG. 1 is employed, the height of piston used in the present invention is reduced, compared with the conventional piston, and so the displacement and compression ratio of engine can be enhanced remarkably. Accordingly, once the piston and connecting rod assembly of the present invention is used in the engine block of a gasoline engine, the gasoline engine can be converted into a diesel engine without drastically changing the design. As shown in FIG. 5, on the other hand, the first piston ring 51 and the second piston ring 52 can be mounted to the upper block 2OA and the lower block 30A, respectively, without forming the rims on the upper and lower blocks. That is, the upper block 2OA corresponds to the lower block 30A, the third piston ring 60 is mounted on a border section of two blocks, and then the first and second piston rings 51 and 52 are mounted on upper and lower portions of the third piston ring 60, respectively. In this state, an upper cover 1OA and a lower cover 1OB are fixed to an upper surface of the upper cover 2OA and a lower surface of the lower block 30A, respectively. Then, the secure mounting state of the first piston ring 51 and the second piston ring 52 can be maintained by the upper cover 1OA and the lower cover 1OB. As mentioned above, the bolt coupling or the rivet coupling is applicable to the process for coupling the upper cover 1OA and the lower cover 1OB to the upper block 2OA and the lower block 2OB.

INDUSTRIAL APPLICABILITY The above embodiment has been described as preferred embodiment of the present invention. However, the scope of the present invention is not limited by the specific embodiments. Further, it should be understood by those skilled in the art that various changes and modifications can be made thereto without departing from the scope and spirit of the present invention.

Claims

WHAT IS CLAIMED IS

1. A piston and connecting rod assembly comprising, a piston block in which a spherical space is formed; a spherical body received rotatably in the spherical space of the piston block; and a connecting rod coupled to the spherical body through a first opening formed at one surface of the piston block to be communicated with the spherical space.

2. The piston and connecting rod assembly according to Claim 1, wherein the piston block consists of an upper block and a lower block, having spherical recesses on one surface thereof, and the recesses form the spherical space.

3. The piston and connecting rod assembly according to Claim 1, further comprising an upper cover covering the spherical body exposed through a second opening, formed on an opposite surface to the surface of the piston block on which the first opening is formed, and communicated with the spherical space.

4. The piston and connecting rod assembly according to Claim 3, wherein the surface of the cover contacting with the spherical body is formed in the spherical shape to correspond to the surface of the spherical body.

5. The piston and connecting rod assembly according to Claim 3, wherein the upper cover is coupled to the piston block through bolts.

6. The piston and connecting rod assembly according to Claim 3, wherein the upper cover is coupled to the piston block by rivet-fixing through the through holes formed on the upper cover and the piston block.

7. The piston and connecting rod assembly according to Claim 3, further comprising a first piston ring mounted between a protrusion structure formed on an outer circumference surface of the piston block and the upper cover.

8. The piston and connecting rod assembly according to Claim 7, wherein the first ring is a compression ring which is spirally wound around the piston block several times in a spiral shape.

9. The piston and connecting rod assembly according to Claim 1, further comprising a lower cover covering the surface of the piston block on which the first opening is formed so that the connecting rod can penetrate the lower cover.

10. The piston and connecting rod assembly according to Claim 9, wherein the lower cover is coupled to the piston block through a bolt.

11. The piston and connecting rod assembly according to Claim 9, wherein the lower cover is coupled to the piston block by rivet-fixing through the through holes formed on the lower cover and the piston block.

12. The piston and connecting rod assembly according to Claim 9, further comprising a second piston ring mounted between the protrusion structure formed on an outer circumference surface of the piston block and the lower cover.

13. The piston and connecting rod assembly according to Claim 12, wherein the second piston ring is an oil scraper ring.

14. The piston and connecting rod assembly according to Claim 7 or Claim 12, wherein the protrusion structure is a third piston ring made of carbon fiber and wounded around the piston block.

15. The piston and connecting rod assembly according to Claim 1, wherein the spherical body consists of upper and lower hollow semispherical bodies, and wherein the connecting rod is coupled to the lower semispherical body through a coupling means penetrating the through hole formed at a lower surface of the lower semispherical body.

16. The piston and connecting rod assembly according to Claim 15, wherein the upper semispherical body and the lower semispherical body are coupled to each other through a hook piece and a protrusion piece formed inside, respectively.

17. The piston and connecting rod assembly according to Claim 15, wherein the coupling means is a bolt.

18. The piston and connecting rod assembly according to Claim 15, wherein the coupling means has a penetrating flow passage formed inside, and the connecting rod has an oil flow passage formed inside, and wherein the penetrating flow passage and the oil flow passage are communicated in fluid with each other to guide oil to the inside of the spherical body.

19. The piston and connecting rod assembly according to Claim 18, wherein the spherical body has a plurality of through holes formed on an outer surface to discharge oil supplied through the penetrating flow passage and the oil flow passage.

20. The piston and connecting rod assembly according to Claim 1, further comprising a ring shaped-bearing section mounted to an inner surface of the semi ring-shaped bearing block formed on an opposite portion of the connecting rod to a portion coupled to the spherical body.

21. The piston and connecting rod assembly according to Claim 20, wherein the bearing section consists of a first semi ring-shaped bearing and a second semi ring-shaped bearing.

22. The piston and connecting rod assembly according to Claim 20, wherein the bearing section has an outer circumference surface, a portion of which is a flat surface, and the bearing block of the connecting rod has a flat surface portion corresponding to the flat surface of the bearing section to fix the bearing section to the bearing block.

23. The piston and connecting rod assembly according to Claim 20, further comprising a band fixed to the connecting rod in the state that the band is wrapped around the outer circumference of the bearing section.

24. The piston and connecting rod assembly according to Claim 23, wherein the band is coupled such that the band is placed in the groove formed on an outer circumference of the connecting rod.

25. The piston and connecting rod assembly according to Claim 23, wherein both end portions of the band are coupled to the connecting rod by a coupling means passing through the connecting rod.