WO2007129792A1

WO2007129792A1 - Power conversion device for internal combustion engine

Info

Publication number: WO2007129792A1
Application number: PCT/KR2006/003544
Authority: WO
Inventors: Jin Euk Choi
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-05-08
Filing date: 2006-09-06
Publication date: 2007-11-15
Anticipated expiration: 2008-11-08

Abstract

Disclosed herein is a power conversion device for an internal combustion engine, which eliminates piston side knock and friction occurring in a cylinder, thus minimizing the loss of power and realizing high durability, therefore improving output performance. According to the present invention, a pair of connecting rods is coupled to a piston to face each other and be symmetrically arranged with respect to the central axis of the piston, thus the pair of connecting rods distributes and transmits force when the piston rectilinearly reciprocates, therefore eliminating side thrust occurring between a cylinder and the piston during vertical movement of the piston, and preventing piston side knock. Thereby, the loss of power is reduced, and durability is increased, so that output performance is improved.

Description

[DESCRIPTION] [INVENTION TITLE]

POWER CONVERSION DEVICE FOR INTERNAL COMBUSTION ENGINE [TECHNICAL FIELD] The present invention relates, in general, to a power conversion device which converts intermittent explosive power into rotary motion and, more particularly, to a power conversion device for an internal combustion engine, which eliminates piston side knock and friction, which occur as a piston rectilinearly reciprocates in a cylinder, thus minimizing the loss of power and realizing high durability, therefore improving output performance. [BACKGROUND ART]

Generally, an internal combustion engine explodes fuel in a combustion chamber having a cylinder, a cylinder head, and a piston, thus providing rectilinear moving force to the piston. While the piston rectilinearly reciprocates in the cylinder, rotating force is transferred to a crank shaft. That is, in order to convert intermittent explosive power generated in the combustion chamber into continuous rotary motion, as shown in FIG 1, a conventional internal combustion engine includes a piston 22 that is provided in a combustion chamber 20 and reciprocates in a cylinder 21, a connecting rod 23 connected to the piston 22, and a crank shaft 24 connected to the connecting rod 23. The internal combustion engine uses the components to transmit force from the piston 22 through the connecting rod 23 to the crank shaft 24, in addition to converting the force into rotating force.

However, such an internal combustion engine is problematic in that friction and piston side knock are caused by side thrust resulting from the operation of the connecting rod 23 and the crank shaft 24, so that a lot of power is consumed, and it is not easy to manufacture an internal combustion engine having sufficient durability to bear the side thrust of the piston, which reciprocates in the cylinder. [DISCLOSURE] [TECHNICAL PROBLEM]

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a power conversion device for an internal combustion engine, which eliminates side thrust resulting from the operation of a connecting rod and a crank shaft, thus eliminating friction and side knock of a piston that rectilinearly reciprocates in a cylinder, therefore minimizing the loss of power and ensuring high durability. [ADVANTAGEOUS EFFECT]

The present invention provides a power conversion device for an internal combustion engine, in which a pair of connecting rods is disposed to face each other and be symmetrically arranged with respect to the central axis of a piston, thus the pair of connecting rods distributes and transmits force when the piston rectilinearly reciprocates, therefore eliminating side thrust occurring between a cylinder and the piston during vertical movement of the piston, and preventing piston side knock. Thereby, the loss of power is reduced, and durability is increased, so that output performance is improved. [DESCRIPTION OF DRAWINGS]

FIG 1 is a view schematically showing the construction of a general internal combustion engine;

FIG 2 is a view schematically showing the construction of a power conversion device for an internal combustion engine, according to the present invention;

FIG 3 is a view schematically showing the construction of FIG 2 at bottom dead center; and FIG. 4 is a view schematically showing the construction of FIG. 2 at top dead center. [BEST MODE]

In order to accomplish the object, the present invention provides a power conversion device for an internal combustion engine, which converts reciprocating motion of a piston performed in a cylinder into rotary motion of a crank shaft via a connecting rod, wherein the connecting rod comprises a pair of connecting rods that face each other and are symmetrically arranged with respect to a central axis of the piston, and the crank shaft comprises a pair of crank shafts that face each other and are symmetrically arranged with respect to the central axis of tiie piston, and force resulting from the rectilinear reciprocating motion of the piston is distributed by the pair of connecting rods and is symmetrically transmitted, so that side thrust of the piston is eliminated by the connecting rods.

According to an aspect of this invention, the pjston includes a head, a skirt contacting a sidewall in the cylinder, and a pair of bosses coupled to the connecting rods, a distance between the head and an end of a skirt being shorter than a distance between the head and the bosses, so that the piston is stepped inwards. According to another aspect of the invention, the piston has a T-shaped cross-section.

According to a further aspect of the invention, the pair of crank shafts includes gears operated in conjunction with the crank shafts, the gears engaging with each other and rotating in opposite directions as the pair of crank shafts rotates.

[MODE FOR INVENTION] Hereinafter, the preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG 2 is a view schematically showing the construction of a power conversion device for an internal combustion engine, according to the present invention, FIG 3 is a view schematically showing the construction of FIG 2 at bottom dead center, and FIG 4 is a view schematically showing the construction of FIG 2 at top dead center. As shown in FIGS.2 to 4, a power conversion device for an internal combustion engine, according to the present invention, includes a cylinder 11, a piston 12, a pair of connecting rods 13 and 13-1, a pair of crank shafts H and 14-1, and a pair of gears 15 and 15-1.

The cylinder 11 is hollow and is open at a bottom thereof. The piston 12 is inserted into the cylinder 11 and rectilinearly reciprocates in the longitudinal direction of the cylinder 11.

The piston 12 has a cylindrical shape. A compression ring is provided at an upper end of the piston 12 and is in close contact with the inner wall of the cylinder 11 to prevent the leakage of gas mixture. An oil ring is provided on the outer surface of the piston 12 to scrape oil from the inner wall of the cylinder 11. As such, the piston may be embodied as a cylindrical piston. However, according to the present invention, the piston preferably comprises a T-shaped piston 12. The T-shaped piston 12 includes a head 12a defining the upper surface of the piston, a skirt 12b which is in contact with the inner wall of the cylinder 11 , and a pair of bosses 12c coupled to the connecting rods 13 and 13-1. Particularly, the T-shaped piston 12 is formed such that the length between the head 12a and the end of the skirt 12b is smaller than the length between the head 12a and the boss 12c.

Further, the T-shaped piston 12 has on a lower portion thereof a pair of bosses which are symmetrically arranged around a central axis, so that the piston is connected to the pair of connecting rods 13 and 13-1. The pair of connecting rods 13 and 13-1 functions to transmit reciprocating motion of the T-shaped piston 12 to the pair of crank shafts 14 and 14-1. One end of each of the connecting rods 13 and 13-1 is connected to the corresponding boss provided on the T-shaped piston 12, while the other end of each of the connecting rods 13 and 13-1 is connected to a respective crank shaft 14 and 14-1. In this case, the connecting rods 13 and 13 - 1 are mounted to face each other while being symmetrically arranged around the central axis of the T-shaped piston 12. Such a construction allows the rectilinear reciprocating motion of the T-shaped piston 12 to be evenly distributed and transmitted without being concentrated on one side.

Like the connecting rods 13 and 13-1, the crank shafts 14 and 14-1 comprise a pair of crank shafts. The crank shafts 14 and 14-1 function to convert reciprocating motion, transmitted through the connecting rods 13 and 13-1, into rotary motion.

Further, the gears 15 and 15-1 are coupled to the corresponding crank shafts 14 and 14- 1 to be operated in conjunction with the crank shafts 14 and 14-1. Thus, as the crank shafts 14 and 14-1 rotate, the gears 15 and 15-1 having the same size engage with each other and rotate in opposite directions. Thereby, side thrust caused by the rotation of the crank shafts 14 and 14-1 is evenly transmitted through the connecting rods 13 and 13-1, which are symmetrically mounted to face each other, to both sides of the T-shaped piston 12. As a result, the side thrust, transmitted to both sides of the piston, cancels itself out.

When the power conversion device for the internal combustion engine of the present invention constructed as described above is driven, as shown in FIG 2, the vertical reciprocating motion of the T-shaped piston 12 is transmitted through the connecting rods 13 and 13-1 to the crank shafts 14 and 14-1. Thereby, the crank shafts 14 and 14- 1 are rotated.

In a detailed description, as shown in FIG 2, in the expansion stroke, the reciprocating motion of the T-shaped piston 12 is distributed by the pair of connecting rods 13 and 13-1, prior to being transmitted to the crank shafts 14 and 14-1. Thus, side thrust generated by the connecting rods 13 and 13-1 cancels itself out. Consequently, side thrust transmitted to the inner wall of the cylinder 11 is eliminated, so that piston side knock and the loss of power are reduced.

In a conventional power conversion device for an internal combustion engine, the skirt of a piston is long so as to dissipate side thrust and transmit it to a cylinder, thus being capable of withstanding side thrust generated during the rectilinear reciprocating motion of the piston. Thus, the cylinder in which the piston reciprocates is also long. However, according to the present invention, the pair of crank shafts 14 and 14-1, arranged symmetrically with respect to the central axis of the T-shaped piston 12, are coupled to the lower portion of the T- shaped piston 12, thus eliminating side thrust. Thus, the piston may use skirts having various lengths. As a result, the piston skirt of the invention may be shorter than the conventional piston skirt, so that the length of the cylinder 11 is reduced.

Further, as shown in FIGS. 3 and 4, A° is larger than B°. Thus, when the piston moves from bottom dead center to top dead center, the rotation angle of the crank shafts 14 and 14-1 is equal to (180 + (A⁰ - B° )/2)°. Thus, the angle is larger than 180°, as in a conventional internal combustion engine, so that an explosion stroke period is increased, thus mitigating the discontinuity of engine torque. Moreover, an intake stroke period is increased, thus improving intake efficiency.

As described above, the present invention provides a power conversion device for an internal combustion engine, in which a pair of connecting rods is disposed to face each other and be symmetrically arranged with respect to the central axis of a piston, thus the pair of connecting rods distributes and transmits force when the piston rectilinearly reciprocates, therefore eliminating side thrust occurring between a cylinder and the piston during vertical movement of the piston, and preventing piston side knock. Thereby, the loss of power is reduced, and durability is increased, so that output performance is improved.

Although the preferred embodiment of the present invention has been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

[CLAIMS]

1. A power conversion device for an internal combustion engine, which converts reciprocating motion of a piston performed in a cylinder into rotary motion of a crank shaft via a connecting rod, wherein the connecting rod consists of a pair of connecting rods that face each other and are symmetrically arranged with respect to a central axis of the piston, and the crank shaft consists of a pair of crank shafts that face each other and are symmetrically arranged with respect to the central axis of the piston, and force resulting from the rectilinear reciprocating motion of the piston is distributed by the pair of connecting rods and is symmetrically transmitted, so that side thrust of the piston is eliminated by the connecting rods.

2. The power conversion device according to claim 1, wherein the piston comprises a head, a skirt contacting a sidewall in the cylinder, and a pair of bosses coupled to the connecting rods, a distance between the head and an end of a skirt being shorter than a distance between the head and the bosses, so that the piston is stepped inwards.

3. The power conversion device according to claim 2, wherein the piston has a T-shaped cross-section.

4. The power conversion device according to claim 1, wherein the pair of crank shafts comprises gears operated in conjunction with the crank shafts, the gears engaging with each other and rotating in opposite directions as the pair of crank shafts rotates.