JP2014070589A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve power transmission efficiency of a piston to a crank shaft.SOLUTION: Reciprocation of a piston 1 is converted into a rotary motion of a crank shaft 6 through a connecting rod 5. The connecting rod 5 has structure in which a first part 5a and a second part 5b are connected together by a knot pin 8. The connecting rod 5 extends straight and a crank arm has a rotation angle of about 90 degrees in a state in which combustion pressure is maximum. Thus, force of the piston 1 can be efficiently transmitted to a crank shaft 6. In an ascending stroke of the piston 1, the connecting rod 5 is bent to prevent the piston 1 from being tensed.

Description

  The present invention relates to a reciprocating internal combustion engine in which reciprocation of a piston is converted into rotation of a crankshaft.

  In a reciprocating internal combustion engine, the power transmission efficiency is best when the crank arm is pushed in a state where it is rotated about 90 degrees, but in general, when the crank pin is at top dead center, the rotation angle of the crank arm is 0 degrees. On the other hand, the combustion pressure becomes maximum at the initial stage when the piston descends from the top dead center during the explosion stroke, and there is a problem that the optimum power conversion efficiency cannot be realized.

  In this regard, in Patent Document 1, the connecting rod is formed in a bent shape, and the crankshaft is shifted slightly from the axial center of the cylinder bore by moving the crankshaft slightly from the top dead center. As described, changing the phase of the crankpin and the phase of the crank arm is described.

JP 2003-172101 A

  In Patent Document 1, it can be said that the function of converting the power of the crankpin into the rotation of the crank arm is somewhat superior because the axis of the crankshaft is greatly deviated from the axis of the cylinder bore. Since the angle of the crank arm is not so different from the conventional one in the state where the most explosive force acts, it is doubtful whether the power conversion efficiency can be improved. In addition, if the crankshaft axis is greatly decentered from the cylinder bore axis, the crankpin and the cylinder bore are in a single contact state, which may promote wear of the crankpin and the crank arm.

  The present invention has been made to improve the current situation.

  The invention of claim 1 has a piston that reciprocates through a cylinder bore, and a crankshaft provided with a crankpin through a crank arm, and the reciprocating motion of the crankpin is connected to the piston and crankpin. In a configuration that is connected by a connecting rod that converts to rotation of the shaft, the connecting rod can be extended and contracted so that the crank arm has a rotation angle exceeding the top dead center when the piston is located at the top dead center. It has become.

  A second aspect of the present invention embodies the invention according to the first aspect. In the present invention, the connecting rod is a link type composed of a first portion and a second portion that are connected so as to be bendable. Adjusting means for automatically changing the degree of bending of the first portion and the second portion in conjunction with the rotation of the first portion and the second portion.

  In the present invention, since the connecting rod moves and expands and contracts, the crank arm can be rotated at a rotation angle of about 90 degrees in the state where the largest explosive force acts on the piston (the combustion chamber is at the maximum pressure). The explosive force acting on the can be efficiently converted into the rotation of the crankshaft. Thereby, output and fuel consumption can be improved.

  In addition, since a large moment can be applied to the crank arm when the combustion pressure is maximum, the crank arm rotation speed and the piston lowering speed can be made faster than before. , Knocking can also be prevented or significantly suppressed.

  Furthermore, since the connecting rod moves while expanding and contracting, it is not necessary to take a measure that greatly shifts the axis of the crankshaft from the axis of the cylinder bore. For this reason, the phenomenon that the piston and the cylinder bore hit each other is prevented or suppressed. Piston and cylinder bore wear can also be suppressed.

  If a link type that automatically expands and contracts by the adjusting means is employed as the connecting rod expansion and contraction means, the structure can be simplified, which is preferable.

It is the schematic for demonstrating a structure and a motion. It is a figure for demonstrating an expansion-contraction mechanism, (A) is a front view which shows the relationship between a crank arm and 1st part, (B) is BB sectional drawing of (A), (C) is 1st part. The front view which shows the connection relation between and 2nd part, (D) is DD sectional view taken on the line of (C).

  Next, an embodiment of the present invention will be described with reference to the drawings. The basic configuration of the internal combustion engine is the same as that of the prior art. A cylinder block 3 having a cylinder bore 2 in which a piston 1 is slidably fitted, a cylinder head 4 fixed to the upper surface of the cylinder block 3, and a connecting rod 5 are used. And a crankshaft 6 for converting the reciprocating motion of the piston 1 into a rotational motion.

  The crankshaft 6 includes a center shaft 6a rotatably held by a journal, a pair of crank arms 6b projecting radially outward from the center shaft 6a, and a crank pin 6c attached to the distal ends of the pair of crank arms 6b. have.

  The connecting rod 5 has a first portion 5a connected to the piston 1 by a piston pin 7 and a second portion 5b connected to the crank pin 6c, both of which are flexibly connected by a knot pin 8. ing. Therefore, the connecting rod 5 is a link system.

  First, the movement will be described. As shown in FIG. 1A, when the piston 1 is at the top dead center, the crank arm 6b is at an angle of about 45 degrees, for example, and the connecting rod 5 is fully extended in this state. As shown in FIG. 1 (B), the crank arm 6b is at an angle of about 90 degrees with the piston 1 lowered to such an extent that the combustion pressure in the combustion chamber is maximized. Efficiency can be secured.

  The connecting rod 5 is in a state of extending linearly until the piston 1 reaches the bottom dead center (see FIG. 1C), and as shown in FIG. 1D, the piston 1 moves upward from the bottom dead center. The connecting rod 5 is bent greatly immediately before the piston 1 rises to the vicinity of the top dead center, and the bending angle of the first portion 5a and the second portion 5b gradually increases in the ascending stroke. It rises while increasing, and at the same time as the piston 1 exceeds the top dead center, the linear state shown in FIG.

  FIG. 2B shows a specific configuration of the adjusting means that automatically bends and stretches. First, in the relationship between the crank arm 6b and the second portion 5b, the second portion 5b rotatably holds the first gear 9 concentric with the crank pin 6c, and meshes with the first gear 9 in the crank arm 6b. The second gear 10 is fixed. Thereby, the relative attitude | position of the said crank arm 6b and the 2nd part 5b is forcedly changed by rotation of the crank arm 6b.

  Next, in the relationship between the first portion 5a and the second portion 5b, as shown in FIGS. 2C and 2D, the first stopper that restricts the relative posture of the second portion 5b to the first portion 5a. 12 and the second stopper 13 are provided to restrict the bending range of both. The second stopper 13 holds the first portion 5a and the second portion 5b in a state of extending linearly.

  Then, by supporting the spring (wire spring or leaf spring) 14 provided in the first portion 5a with the spring receiving stopper 15 provided in the first portion 5a, both are biased so as to shift to a bent posture. ing. Thereby, when the piston 1 shifts to the ascending stroke, the connecting rod 5 becomes bent and the connecting rod 5 is prevented from being stretched.

  Other configurations can be adopted as means for automatically bending and stretching the connecting rod. In addition, the connecting rod may be configured to be telescopic so as to expand and contract according to the rotation of the crankshaft.

  The present invention can be embodied in an internal combustion engine. Therefore, it can be used industrially.

DESCRIPTION OF SYMBOLS 1 Piston 2 Cylinder bore 3 Cylinder block 5 Connecting rod 5a 1st part 5b 2nd part 6 Crankshaft 6a Center axis 6b Crank arm 6c Crankpin 6c 7 Piston pin 8 Knotting pin

Claims (2)

A connecting rod that has a piston that reciprocates through a cylinder bore and a crankshaft provided with a crankpin via a crank arm, and that converts the piston and crankpin into revolving motion of the crankpin into rotation of the crankshaft It is the composition connected with,
The connecting rod can be expanded and contracted so that the crank arm has a rotation angle exceeding the top dead center when the piston is located at the top dead center.
Internal combustion engine. The connecting rod is a link type composed of a first part and a second part that are connected so as to be bendable, and automatically adjusts the degree of bending of the first part and the second part in conjunction with the rotation of the crankshaft. With adjustment means to change
The internal combustion engine according to claim 1.

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