JP2000130201A - Compression ratio improving device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve fuel consumption rate and to clean up exhaust gas due to complete combustion by changing the compression ratio of an internal combustion engine according to a driving situation in order to always keep mean effective pressure high from low load to high load and improve indicated thermal efficiency. SOLUTION: A compression ratio improving device 1 has a structure wherein a plunger 8 and a rack gear shaft 7 are driven according to a load by a hydraulic cylinder 9 to rotate a gear 6 meshing therewith, thereby rotating an upper middle back plate A and a lower middle back plate B which are integrally formed with the gear 6. The upper and lower middle bearing metals A, B move a shaft center position of main bearing metals 4, 5 and crank journal 10 at the time of rotating because of an eccentric structure thereof, thereby changing a top dead center position and a bottom dead center position of a piston. At the time of low load, a space capacity is made to be small by moving up the top dead center position of piston, which causes a high compression ratio state. And at the time of rated road, the space capacity is made to be large by moving down the top dead center position, which decreases the compression ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0101]

BACKGROUND OF THE INVENTION The present invention realizes complete combustion from a low load range to a high load range for an internal combustion engine in general, particularly a vehicle engine in the field of industrial machinery, and increases the average effective pressure to improve the indicated thermal efficiency. The goal is to provide improved fuel economy and reduced emissions.

[0092]

2. Description of the Related Art Conventionally, as a method of improving the illustrated thermal efficiency in an internal combustion engine, a method of changing the shape of a piston top to generate a vortex, increasing the number of intake / exhaust valves to increase intake efficiency, and directly injecting fuel have been known. is there.

In the conventional method, the improvement of the indicated thermal efficiency is remarkable at the rated load and the rated speed of the engine. The absolute amount of intake is small and the compression pressure does not increase at the end of the compression stroke. Accordingly, a sufficient compression temperature cannot be obtained and the cylinder wall temperature is low, so that a part of the combustion chamber does not reach the ignition temperature, causing incomplete combustion and causing a marked decrease in the indicated thermal efficiency.

In an exhaust turbine supercharged engine, if the supercharging ratio is set high in order to obtain high efficiency in the rated load range, the filling amount of the combustible air-fuel mixture in the cylinder increases in the high load range, and the maximum pressure in the cylinder (hereinafter referred to as Pmax) Therefore, it is necessary to keep the compression ratio low for safety. But,
When the compression ratio is set low, the supercharging effect of the exhaust turbine is low in a low load range, so that the filling amount in the cylinder is small and sufficient compression pressure and temperature cannot be obtained at the end of the compression stroke, and Pmax also decreases. Therefore, the indicated thermal efficiency is reduced and the performance at low load is deteriorated.

An object of the present invention is to provide a device capable of appropriately improving a compression ratio in an internal combustion engine in order to maintain Pmax, which is remarkable for improving the indicated thermal efficiency, high even at low load and low rotation. That is, when the load is low, the compression ratio is set high, the compression pressure and compression temperature are increased, Pmax is improved, the average effective pressure is improved, and the indicated thermal efficiency is improved.

[0056]

The structure of the compression ratio improving device (1) of the present invention has an eccentric circular structure in which the cross section of the main bearing of the internal combustion engine is divided into upper and lower parts and a part of the outer periphery has a gear (6). Upper middle backing (A) and lower middle backing (B), upper backing (2) and lower backing (3) for supporting the upper and lower middle backing (A) (B), and lower backing (3) And a rack gear (7) meshed with the gear (6) of the upper and lower intermediate backing plates (A) and (B), a hydraulic cylinder (8) for driving the rack gear, and a plunger (9). And

[0086]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to FIGS. FIG. 1 is a sectional view of a compression ratio improving device (1). FIG. 2 is an axial sectional view of a compression ratio improving device (1).
FIG. 3 is a schematic configuration diagram showing a state where the present apparatus has shifted to a high compression ratio side. FIG. 4 is a schematic configuration diagram showing a state where the present apparatus has shifted to a low compression ratio side.

The configuration of each part of the compression ratio improving device (1) of the present invention will be described. As shown in FIGS. 1 and 2, the upper intermediate back metal (A) and the lower intermediate back metal (B) are vertically divided into two parts in cross section, and at the same time, the gear (6) is also divided into two parts. The upper and lower middle backing metal (A) and (B) are tightened from below by the tightening bolt (13). A bolt insertion hole is provided and the tightening bolt is a reamer bolt.

In an engine having a lubricating hole in the crank bearing body and forcibly lubricating the crankpin bearing and the piston pin bearing, an oil groove and an oil hole are provided inside and outside the upper and lower intermediate backing plates (A) and (B). To make it smooth.

The gap (a) between the upper and lower intermediate backing metal (A) and (B) and the upper and lower backing metal (2) and (3) is minimized as long as the gear can rotate. The upper / lower intermediate backing metal (A) (B) holds the main bearing metal (4) (5) inside.

The upper back metal (2) and the lower back metal (3) support the upper and lower middle back metals (A) and (B), and the lower back metal (3)
Is provided with a rack gear chamber (12) capable of accurately supporting a rack gear shaft (7) for driving the gear (6).

[0111]

Next, an embodiment of a compression ratio improving apparatus will be described.
Main bearing metal (4) on crank journal (10)
(5) The upper intermediate backing metal (A and the lower intermediate backing (B)) are firmly tightened with the mounting bolts (13). At this time, the gap (b) is an appropriate one that can provide sufficient oil lubrication when the journal rotates at high speed. And

Gears (6) of upper and lower intermediate backing metal (A) (B)
Into the upper back metal (2). With the rack gear (7) inserted into the rack gear chamber (12) of the lower back metal (3), the lower back metal (3) is attached to the upper back metal (2) and fixed with tightening bolts. At this time, upper and lower back metal (2) (3)
It is confirmed that the upper and lower intermediate back metals (A) and (B) can rotate together with the gear (6) by moving the rack gear (7).

The positional relationship between the gear (6) and the rack gear (7) is such that when the upper and lower intermediate backing plates (A) and (B) rotate and the crank journal (10) is at the apex of the eccentric circle, the piston moves up to this position. Position.

As another embodiment, as a method of driving the gear (6), there is a method of driving the worm gear shaft by rotating the shaft with a meshing motor or the like.

[0151]

The compression ratio improving device of the present invention is a device which can change the compression ratio of the internal combustion engine during operation.
That is, when the load is low, a high compression ratio operation is performed and Pmax is increased to increase the indicated thermal efficiency. At a rated load, the state is set to a low compression ratio state and the indicated thermal efficiency at the rated engine speed can be set as high as possible. Therefore, when obtaining the same output, the engine can be made smaller and lighter than before, and the economic efficiency can be greatly increased in addition to the downsizing of the accessory equipment. Further, maintaining Pmax high in an engine having a large load variation means complete combustion of the combustible air-fuel mixture in the cylinder, and the exhaust gas can be cleaned at the time of generation.

[Brief description of the drawings]

FIG. 1 is a sectional view of a compression ratio improving device (1) of the present invention.

FIG. 2 is an axial sectional view of the compression ratio improving device (1) of the present invention.

FIG. 3 is a schematic configuration diagram illustrating a state where the present apparatus has shifted to a high compression ratio side.

FIG. 4 is a schematic configuration diagram showing a state where the present apparatus has shifted to a low compression ratio side.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Compression ratio improvement apparatus 2 Upper back metal 3 Lower back metal A Upper middle back metal B Lower middle back metal 4 Main bearing metal 5 Main bearing metal 6 Gear 7 Rack gear shaft 8 Plunger 9 Hydraulic cylinder 10 Crank journal 11 Gear groove 12 Rack gear chamber 13 Tightening bolt P Piston Z Top clearance X Cylinder head lower cr Connecting rod a Upper / lower back metal 2.3 and upper / lower middle back metal A ・
Gap of B b Gap between main bearing metals 4 and 5 and crank journal 10 Zh Piston gap volume in high compression ratio state Ph Piston height in high compression ratio state Ch Centerline of crankshaft in high compression ratio state ZL Low compression ratio state Piston gap volume PL Piston height in low compression ratio state CL Crankshaft center line in low compression ratio state

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) F16C 27/02 F16C 27/02 Z

Claims (1)

[Claims] 1. A cross section of a main bearing portion of an internal combustion engine, which is located between an upper back metal (2) and a lower back metal (3) and holds the main bearing metal (4) (5) inside, is an eccentric circle. A rack gear (7) held by the upper middle back metal (A), the lower middle back metal (B), and the lower back metal (3) and meshing with the gear (6), and a hydraulic cylinder for driving the rack gear (8) A variable compression ratio device comprising a plunger (9).