FR2706182A1 - Lubricant recycling device in an internal combustion engine. - Google Patents

Abstract

- The invention relates to a device for recycling a lubricant accumulated in a capacity (11) of an internal combustion engine with pneumatic fuel injection, the capacity connecting the pump housing (8) of said engine to an intake passage fuel mixture under pressure in the combustion chamber (1), the passage being equipped with an intermittent shutter element (6) and the capacity (11) comprising a non-return valve (12). - According to the invention, there is provided at least one calibrated passage (14) passing through the partition wall between said capacity (11) and said pump casing (8). Further, the end of the passage (14) through which the lubricant leaves the capacity (11) is located at the lowest point of the capacity (11).

Description

The present invention relates to the field of internal combustion engines

  in two stages in which an injection

  fuel pneumatic is performed.

  In this type of engine, the pressure source necessary for the pneumatic fuel injection can be external to the engine, or it can be internal: in the latter case, the pressure source can be constituted by the cylinder crankcase in which the injection takes place either by the cylinder itself or by a

  another pump housing or by another cylinder.

  It is also known to use the exhaust pressure to perform a pneumatic injection: the document FR-2,621,648

discloses such an engine.

  Document FR-2.575.523 shows an internal combustion engine which in fact combines two sources of pressure: the pump housing

  and exhaust to improve pneumatic injection.

  For the engines to which the invention applies, the outside air admitted into the pump housing by any means known per se is therefore put under pressure in the pump housing itself by the movement

descending from the piston.

  This air can leave the pump housing by two types of ducts: In the first type of so-called "transfer" ducts, air is conveyed from the pump housing to the combustion chamber. This non-carburetted air is introduced before the admission of air used for pneumatic injection, in order to carry out a scanning of the

combustion chamber.

  Another part of the air contained in the pump casing escapes through one or more conduits connected in addition to the

  combustion. These conduits are generally fitted with a check valve.

  return. 3 O So when the pressure of the pump crankcase is higher than a certain value, the non-return valve opens a line (or capacity) connecting the pump crankcase to the fuel mixture intake passage in the combustion chamber. Since the valve closes when the pressure in the pump casing becomes lower than the pressure in the line, the latter can be considered as a pressure storage capacity since the fluid which passes through it is at a pressure greater than or equal to the maximum pressure prevailing in the pump housing. In fact, the air from the pump housing contains a certain amount of lubricant. This lubricant is first introduced with the air admitted into the pump housing to lubricate the moving parts

bearings, piston, sleeve ...

  The air which then passes through the tank remains charged with lubricant. When the air thus charged crosses the capacity, part of this lubricant can be deposited on the walls, in layers and then it can

  for example, accumulate in the lower capacity area.

  The problem encountered in such engines results from the accumulation of lubricant in the bottom of the tank. In fact, this very densified lubricant is driven, for example when the vehicle is started, directly towards the intake orifice used for the pneumatic injection of fuel mixture into the cylinder, so that it is injected in a very densified in the combustion chamber. This disrupts combustion and creates emissions of

exhaust fumes.

  A similar problem has already been mentioned in the prior art, for example in document US-4,280,456 which provides porous seals around the intake ports, seals intended to absorb the lubricating oil discharged from the lower part of the cylinder. . Drains start from the joints and extend into the pump housing

  in order to recycle the oil thus recovered.

  US Pat. No. 4,962,745 discloses another way of solving this problem: this document teaches placing oil separators on a compressed air line necessary for injection under pressure. These additional means can be designed in different ways. They are usually connected to a pipe which brings back the oil

-in the pump housing.

  The present invention provides a simple solution which is easy to implement and which responds well to the problem created by the accumulation of lubricant in a pressurized gas line.

  participating in pneumatic injection.

  The present invention is particularly well suited to two-stroke engines whose pneumatic injection line is

connected to a pump housing.

  The invention relates to a device intended for recycling a lubricant accumulated in a capacity of an internal combustion engine with pneumatic fuel injection, the capacity connecting the crankcase of said engine to an inlet for admitting fuel under pressure. in the combustion chamber, the intake port being equipped with an intermittent shutter element and the

  capacity including a non-return valve.

  The device according to the invention is characterized in that it comprises at least one calibrated passage passing through the partition wall between said capacity and said pump housing, and in that the end of the passage through which the lubricant leaves the capacity is located at the point

the lowest of said capacity.

  1 O More specifically, the cross section of the passage (s),

  side of said capacity, can be between 0.5 mm2 and 10 mm2.

  According to one embodiment of the invention, the passage or passages

  may have a constant section over their entire length.

  According to another embodiment of the invention, the passage or passages may have a non-constant section over their entire length. Other characteristics, details and advantages of the invention

  will appear better on reading the description which follows, made at

  illustrative title and in no way limitative with reference to the single figure

2 0 attached.

  This figure shows a longitudinal section through a motor

to which the invention applies.

  The engine may comprise, in a known manner, at least one cylinder

  1 in which slides a piston 2 moved by a connecting rod system

  crank 3, an exhaust duct 4, an ignition element 5, such as a spark plug, an intermittent shutter element of the intake such as a valve 6, at least one transfer duct 7 intended to bring the air from sweeping from a pump housing 8 into the

combustion chamber 1.

  3 O An inlet 9 provided with an adjustment element 10 allows

  to admit outside air into the pump housing 8.

  Most of this outside air passes through the transfer duct (s) 7 in order to sweep the

  combustion as explained at the beginning of the description.

  Another part of the air present in the pump housing 8 is expelled, at certain times in the combustion cycle, to a duct

  11 connecting the pump housing 8 to the combustion chamber 1.

  As explained above, the conduit 11 is in fact a pressure storage capacity since it is provided with a non-return valve 12

  preferably placed near the pump housing 8.

  An injector 13, known per se, is placed near the other end of the tank 11 in order to introduce fuel into the stream of pressurized air. The injector 13 being placed just upstream of the valve 6, a fuel mixture is formed in this zone located near the intake orifice (not referenced) which, of course, is injected into the combustion chamber when the

  valve is far from its seat.

  As has already been said when mentioning the problem underlying the present invention, lubricant can accumulate in particular

at the bottom of capacity 11.

  In order to remedy this drawback, it is proposed to provide

  1 5 minus a calibrated passage 14 at the bottom of the capacity 11.

  The calibrated passage 14 preferably provides a

  communication between the capacity 11 and the pump housing 8.

  According to the preferred embodiment illustrated by the single appended figure, the calibrated passage 14 has a substantially vertical axis (not referenced); the axis of the engine cylinders being inclined by about 20 in the example of this figure. Vertical orientation

  facilitates the downward flow, that is to say towards the pump housing.

  Thus, as already explained, the oil (or any other lubricating element) which accumulates by gravity at the bottom of the capacity 11

can flow through passage 14.

  The passage 14 must be of small section so as not to generate a pressure drop in the capacity 11. The cross section of the

  passage 14 may or may not be constant over its entire length.

  Tests have been made with a passage having a section

  constant of 1 mm2. They gave complete satisfaction.

  Preferably, only one passage is planned. In some cases, it may be necessary to provide several passages. In any case, the section of the passage or the cumulative section of the passages, on the capacity side,

  is between 0.5 mm2 and 10 mm2.

  According to the invention, the oil is therefore returned directly to the pump housing 8 where it is sprayed by the positive pressure difference prevailing between the capacity 11 and the pump housing 8 during the major part of the engine rotation cycle. The oil can thus, by

  this recycling, again contribute to the lubrication of the engine.

  Of course, other modifications and / or additions can be imagined by those skilled in the art to the device which has just been described, without departing from the scope of the present invention.

Claims (4)

  1.- Device intended to recycle a lubricant accumulated in a capacity (11) of an internal combustion engine with pneumatic fuel injection, the capacity connecting a crankcase (8) of said engine to a fuel mixture intake orifice under pressure in the combustion chamber (1), the orifice being equipped with an intermittent closure element (6) and the capacity (11) 1 0 comprising a non-return valve (12), characterized in that it comprises at least one calibrated passage (14) passing through the partition wall between said capacity (11) and said pump housing (8), and in that the end of said passage (14) through which the lubricant leaves said   capacity (11) is located at the lowest point of capacity (11).   2.- Device according to claim 1, characterized in that the cross section of the passage (s) (14), on the side of said   capacity (11), is between 0.5 mm2 and 10 mm2.   3. - Device according to any one of claims   previous, characterized in that the passage (s) (14) have   a constant section over their entire length.   4. - Device according to any one of claims 1 or 2,   characterized in that the passage (s) (14) have a cross section   not constant over their entire length.   - Device according to any one of the claims   previous characterized in that the calibrated passage (s) (14)   have a longitudinal axis oriented vertically.