FR2496166A1 - TWO-STROKE ENGINE WITH SUCTION DISTRIBUTION BY TWO DISC VALVES - Google Patents

Abstract

The invention relates to a two-stroke engine with rotary disc valve control by means of two disc valves mounted on both sides of the crankshaft. To obtain an optimum volumetric efficiency of the engine, the valves are arranged in the crank case between the arms of the crankshaft and the main bearings of the crankshaft, more particularly at the outer side faces of the crankshaft arms. To provide good sealing, the rotary discs can be displaced to a limited extent in the direction of the axis of the shaft and are secured against independent rotation. The arms are connected to one another by means of grooved projections with claws, a screw and the inner ring of the big end bearing. The engine is simple to construct because special disc chambers and their seals are eliminated. The crankshaft is likewise simpler to manufacture.

Description

 The present invention relates to a two-stroke internal combustion engine with suction distribution using two rotating disc valves which are placed on both sides of the crankshaft.

 Two-stroke engines are known with suction distribution using a valve in the form of a rotating disc which is placed directly on 1% crankshaft and engines where the actuation of the disc valve is carried out directly by flanges of the crankshaft. In known embodiments, disc valves are usually placed at the end of the crankshaft and the valves move in a separate jacket. There is also known a case where the engine has two disc valves placed in separate jackets. For the engine comprising a single disc valve, an arrangement has been made in which the disc valve moves directly into the crankshaft chamber and is carried by a pin sliding in an auxiliary hole in the crankshaft arm.

 The disadvantage of all engines with a disc valve is the impossibility of efficient filling in order to obtain the maximum specific power.

In known arrangements comprising two disc valves placed at the ends of the engine, suction ducts are obtained which are excessively long and in addition the width of the engine is exaggeratedly increased. In the engine where the distribution element directly forms the crankshaft, the seal cannot be satisfactory due to thermal expansions and other effects.

 The above-mentioned drawbacks are eliminated using a two-stroke internal combustion engine with suction distribution by two disc valves in accordance with the present invention, the disc valves being placed in the volume defined by the crankshaft case between the crankshaft flanges and the main bearings of the latter. The two disc valves are fixed to the outer faces of the crankshaft flanges with the possibility of axial displacement, the flanges being mutually connected, using grooved projections associated with jaws and a screw and using a inner ring of the crankpin bearing.

This particular method of connecting the crankshaft flanges without using conventional connecting rod axes makes it possible to machine the outer faces of the two flanges so as to provide a space allowing the passage of a mixture of
combustion and to give an advantageous profile to the intake channel without any increase in the advantage of the diameter of the two disc valves, which would necessarily cause
also a lengthening of the connecting rod and an increase in the dimensions of the entire engine.

The advantage of the arrangement according to the invention
is that it is possible to ensure a filling
more efficient engine, which satisfies the condition
prerequisite to reach the maximum possible specific power and to obtain a favorable combustion of the fuel. Also for a two-engine
disc valves, engine construction is relatively simple due to the elimination of special liners
for the valves and their packing. The
design of a crankshaft without separate connecting rod axis is
also much simpler, from a manufacturing point of view,
than a crankshaft made in one piece and filling
the same function.

Other advantages and characteristics of the invention
will be highlighted in the following description,
given by way of nonlimiting example with reference to
single attached drawing which is a schematic vertical section
of the motor.

A cylinder 2 closed by a cylinder head 3 is fixed on the
casing 1 of an engine. Crankshaft 4 is rotatably mounted
in main bearings 5 which are placed in the
crankcase 1. The crankshaft 4 is formed of
two flanges 6 having projections 7 provided with jaws
front 8. The two flanges 6 are firmly applied against one another by a screw 9. The inner ring 10 of the bearing 11 of the crank pin 12 is fitted on the outer periphery of the projections 7 provided with the jaws 8.

Disc valves 15 are fixed on the outer faces 13 of the flanges 6 using carrier pins 14, said valves being able to execute a small axial movement.

A lining allows this displacement under the effect of an instantaneous overpressure or depression in the crankshaft volume. The disc valves 15 open and close through their openings, not shown in the figure, the intake pipes 16. Carburetors, not shown, are placed on the suction pipes 17 leading to the intake pipes.

Claims (2)

 l.Two-stroke internal combustion engine with suction distribution by two disc valves placed on both sides of the crankshaft, characterized in that the two disc valves (15) are placed in the volume of the crankshaft housing between flanges (6) of the crankshaft (4) and the main bearings (5) of the crankshaft (4).  2. Two-stroke internal combustion engine according to claim l, characterized in that the two disc valves (15) are fixed on the external faces (13) of the flanges (6) of the crankshaft (4) with possibility of axial displacement. , the flanges (6) being interconnected by means of projections (7) comprising front jaws (8), of a screw (9) and by means of an inner ring (10) of the bearing ( 11) connecting rod crankpin (12).