EP0625631B1 - Improved rotary valve - Google Patents

Abstract

The present invention relates to a substantially cylindrical rotary spool (valve) intended for the inlet of a fluid into a combustion chamber of an internal combustion engine, including at least one elbowed internal duct (1, 1') for the flow of the said fluid, each duct having an inlet orifice (2, 2') situated on the lateral flank of the said spool, an outlet orifice (3, 3') belonging to the cylindrical surface of the said spool, and an elbow (20, 20') intended to hold back the heaviest elements of the fluid under the effect of centrifugal force, the thickness (21, 21') of the wall of the spool between the outer face of the duct and the outside of the spool being relatively slight in the region of the said elbow (20, 20'). According to the invention, at least one of the outlet orifices (3, 3') of at least one of the said ducts and at least one of the said elbows (20, 20') belong to one and the same transverse section of the spool. <IMAGE>

Description

The present invention relates to a rotary valve for transferring a fluid between a fluid source and a combustion chamber of an internal combustion engine, comprising at least one substantially cylindrical surface and a lateral flank.

The present invention relates more particularly to a rotary valve for controlling the admission of gas, in particular of an air-fuel mixture into a combustion chamber of an engine, comprising an intrinsic sealing system.

The present invention applies to two-stroke or four-stroke internal combustion engines having one or more cylinders supplied by a gas, in particular an air-fuel mixture.

The distribution of a fuel mixture into the combustion chamber can be carried out, in a known manner, by parts driven by a reciprocating movement such as valves. The applicant has protected, in French patent application FR-2,655,653 a system of this type.

However, the performance of the engine can be limited by the injection systems with valves, in particular with regard to the control of the beginning and the end of the injection and the section of passage of the carburetted air (oscillation problems ).

In addition, these systems must be mounted in relatively large cylinder heads. An improvement consists in using rotary plugs for the control and the distribution of a fuel mixture.

Thus, in French patent application FR-2,662,214, provision is made for the use of rotary plugs for controlling the pneumatic injection of fuel in a two-stroke engine.

The bushels thus disclosed have an axis of rotation situated in a plane perpendicular to the axis of the cylinder, are pierced with a transverse channel for communicating the intake duct and the combustion chamber and are connected to means d drive allowing them to rotate as a function of the rotation speed of the engine crankshaft.

Vis-à-vis the valves, such plugs can therefore operate at higher speed and allow greater flexibility in adjusting the injection.

However, there remain sealing problems in particular at the inlet of the plug.

Sealing devices are sometimes provided for this purpose, either upstream or downstream of each plug, or in both places.

Patent application FR-2,559,208 relates to a plug for controlling the exhaust and / or the admission of gas from and / or to a combustion chamber to which one or more sealing members is applied. The improvement envisaged in this prior art consists of lubrication and cooling of the contact surface between the sealing member (s) and the plug.

Due to its sophistication, it is not certain that this system is perfectly reliable, particularly in terms of sealing.

It is also known, from patent application FR-2,679,960 filed in the name of the applicant, a rotary plug for which the sealing at the inlet is ensured by the shape and the very arrangement of a channel drilled in the bushel.

More specifically, this plug comprises at least one flow channel of said fluid having an inlet orifice and an outlet orifice, the inlet orifice belongs to said lateral surface of the plug and is placed at a non-zero distance from l the axis of rotation of the plug while the outlet orifice belongs to the cylindrical surface of said plug and is offset radially relative to the inlet orifice.

The flow channel disclosed by this prior art comprises an intrinsic fuel trapping means consisting of an elbow formed by said channel and capable of retaining said fuel under the effect of the centrifugal force created by the rotation of the plug.

The present invention relates to an improvement made to the latter type of plug.

In fact, the present invention relates to a rotary plug with intrinsic sealing which also allows better heat exchange with the surrounding elements.

In particular, it has been found that the plug with intrinsic tightness according to the prior art has hot zones in which thermal stresses develop which can cause deformations of the plug.

The optimization of the heat exchange obtained according to the invention therefore not only makes it possible to reduce the thermal stresses but also to take advantage of the heating of certain zones to heat the fuel present near the zone (s) hot. This heating, by creating a vaporization of the fuel, allows a better preparation of the fuel mixture. This mixture is thus partially homogenized before it is introduced into the combustion chamber.

The advantages and improvements which have just been stated are notably obtained by a substantially cylindrical rotary plug intended for the admission of a fluid into a combustion chamber of an internal combustion engine, comprising at least one internal channel bent by flow of said fluid, each channel having an inlet orifice situated on the lateral flank of said plug and an outlet orifice belonging to the cylindrical surface of said plug, the thickness of the wall of the plug between the external face of the channel and the outside bushel being very weak at the elbow.

According to the invention, at least one of the outlet orifices of at least one of said internal channels and at least one elbow belong to the same cross section of the plug.

Advantageously, at least one of said elbows of at least one of said channels is placed in such a way that its upper surface faces the inlet opening of the cylinder head during the combustion phase.

According to the invention, the profile of the channel is such that the mixture first crosses the plug substantially longitudinally to exit in a substantially radial direction.

According to one embodiment, the channel successively has two bends, the first to reverse the direction of the substantially longitudinal flow, the second bend intended to have a radial flow at the outlet.

Preferably, the rotary plug has two channels arranged symmetrically with respect to an axial plane.

The zone of the channel located near the entrance of the channel has at least one strongly inclined face in order to effectively direct the mixture inside the bushel.

• la figure 1 est une perspective éclatée montrant un mode de réalisation de l'invention,
• les figures 2, 3, 4, et 5 sont des coupes transversales selon respectivement A, B, C et D de la figure 1,
• la figure 6 est une perspective montrant la géométrie des canaux selon un autre mode de réalisation de l'invention, et
• les figures 7, 8, 9 et 10 sont des coupes transversales selon A', B', C' et D' de la figure 6.

Other advantages and particular features of the invention will appear better on reading the description which follows, given by way of illustration and in no way limiting, with reference to the appended drawings in which:

• FIG. 1 is an exploded perspective showing an embodiment of the invention,
• FIGS. 2, 3, 4, and 5 are cross sections according to A, B, C and D respectively in FIG. 1,
• FIG. 6 is a perspective showing the geometry of the channels according to another embodiment of the invention, and
• Figures 7, 8, 9 and 10 are cross sections along A ', B', C 'and D' of Figure 6.

Figure 1 shows an exploded perspective example of a rotary valve according to the invention.

In this figure, only an internal channel 1 is shown, essentially for the sake of clarity of the figure. Preferably, the plug according to the invention comprises two identical channels, arranged symmetrically with respect to an axial plane of the plug.

Each channel may comprise, in known manner, an inlet orifice 2 of the mixture, belonging to the lateral surface and an outlet orifice 3 forming part of the cylindrical surface of the plug.

Near the inlet orifice 2, the channel is substantially oriented parallel to the longitudinal axis. Near the outlet orifice 3, the channel is preferably oriented radially.

Each channel advantageously has at least one bend 4, the thickness of the wall at the bend being relatively small.

The elbow has a concavity turned towards the outside of the plug so as to form, under the effect of centrifugal force, a retention pocket 20 for the component (s) heavier (s) of the mixture .

This feature can be obtained with the channel geometry shown in FIG. 1, and detailed by the sections in FIGS. 2 to 5.

In FIG. 2, which illustrates a section located near the inlet of the plug, two channels 1 and 1 ′ appear in the form of a portion of the crown and arranged symmetrically with respect to the axial plane δ ₂ .

FIG. 3 is a section little different from that of FIG. 2. The plane of symmetry a3 has turned slightly with respect to the plane of symmetry δ2. Each channel is therefore twisted between these two cuts. One of the faces 11, 11 'of each channel has not changed orientation while the other face 12, 12' defines a smaller opening angle. Therefore, between sections A and B, the area of each defined channel by faces 12 and 12 'is strongly inclined. This characteristic makes it possible to better direct the fluid inside each channel.

It is also noted that between sections A and B, the thickness of the wall between the external face of each channel 1, 1 'and the external surface of the plug, has clearly decreased.

In Figure 4, appear, for each channel 1, 1 ', a retention pocket 20, 20', an intermediate zone 30, 30 'and an outlet zone of the mixture 40, 40'.

Figure 5, which corresponds to a section close to the bottom of each channel, looks like Figure 4. The following comments are valid for each of these figures.

In Figures 4 and 5, it appears in particular that the wall 21 near the retention pocket 20 is very thin. This allows, as has already been said, to promote heat exchange between the outside of the plug and the fuel present inside the pocket. Thus, it is preferable to choose to pass the bag 20 in front of the combustion chamber inlet orifice at the time of combustion, that is to say at the hottest time of the cycle. This makes it possible to heat the fuel present near the walls of the pocket 20.

In addition, this heat exchange cools the wall 21.

The intermediate zone 30, 30 'of each channel consists of a narrowing of the pocket 20, 20' to lead to the zone 40, 40 'of substantially tubular outlet. The axis of the tubular zone 40, 40 'is preferably radial in order to promote the speed of the fluid leaving.

The flow of the fluid through the channel according to the invention is therefore the following. The fluid enters each channel through the inlet orifice 2 located on the lateral flank of the plug, and thanks to the inclination mentioned above, it is rapidly directed towards the interior of the channel; the fluid then travels along a path substantially parallel to the longitudinal axis of the plug, the thickness of the wall of the channel becoming smaller as the penetration into the plug.

Then the fluid meets a semi-spherical background which gives it a first change of direction almost at 180 °. This first change in direction is followed by a second change created by the wall of the canal. This second change of direction gives a quasi-radial orientation at the channel at its outlet 3 towards the combustion chamber.

The quasi-radial orientation of the outlet zone of the channel 40, 40 'allows good injection into the combustion chamber.

In addition, the fact that the outlet zone 40, 40 'of the channel and the retention pocket 20, 20' are preferably located longitudinally at the same level of the plug, allows the retention pocket to face a certain phase. of the operating cycle, at the inlet, that is to say at the combustion chamber.

The direction of rotation as shown in FIGS. 1 to 5 is an example according to which the outlet orifice 3 of a channel comes first opposite the inlet orifice of the combustion chamber, then the pocket 20 of the same channel passes in front of this same orifice in the direction of rotation indicated in FIGS. 1 to 5.

Thus, according to this example, the fuel mixture is first injected into the combustion chamber (intake phase), then a few degrees crankshaft later, the pocket 20 comes opposite the intake orifice. At this time combustion takes place (or has just occurred) so that a large mass of energy is released from the combustion chamber. Part of this energy can therefore be transmitted to the pocket 20; the transmission is all the more important as the wall thickness of the plug is thin in this zone.

Consequently, the fuel (for example) which is trapped in this pocket 20 under the effect of centrifugal force, is heated as it passes opposite the intake orifice. This heat exchange is favorable for vaporization of the fuel in the air, that is to say an improvement in the preparation of the mixture before it is introduced into the combustion chamber.

In addition, the therms are thus advantageously captured by the fuel so that the wall 21 of the plug is never subjected to overheating liable to degrade it.

Of course, each channel 1, 1 ′ passing successively in front of the intake orifice, what has just been stated relative to one channel is also true for the other channel.

In another example not shown, the plug rotates in the opposite direction to that indicated in FIGS. 1 to 5. In this case, after injection into the cylinder through an outlet orifice 3 of a channel 1, the pocket 20 'of the other channel 1' comes opposite the intake orifice during combustion. This other implementation of the invention allows more time to introduce the fuel into the plug if one wishes to benefit from the preheating effect of the fuel, the aid for vaporization of the fuel and the cooling of the wall. .

Another embodiment of the invention, illustrated by FIGS. 6 to 9 also makes it possible to obtain the characteristics set out above.

FIG. 6 schematically represents the geometry of the channels 1, 1 ′ and their positioning in a plug according to another embodiment of the invention.

For each channel considered, the following preferential elements are common with the previous embodiment of the invention:

A retention pocket 20, 20 'and an outlet 3, 3' located substantially in the same transverse plane; a small wall thickness 21, 21 ′ at the level of the pocket; a profiled channel inlet to promote the penetration of the fluid; an exit zone 40, 40 'oriented substantially radially.

The sections of Figures 7, 8, 9 and 10 allow a better understanding of the geometry of each channel. As in the previous embodiment, two channels are provided, symmetrical with respect to an axial plane.

The differences with respect to the previous embodiment of the invention lie essentially at the bottom of each channel which here describes a bend 25 in the form of a hairpin which creates a change in the direction of circulation of the fluid. A connection zone 35 is also provided between the elbow 25 and the radial outlet zone 40.

The flow of the fluid in each channel 1 is first substantially longitudinal, then a reversal of direction takes place before the radially oriented outlet.

Figures 7 and 8 show the change in geometry from input A 'to level B' in Figure 6. This change will not be further discussed since already explained for the previous embodiment.

Figure 9 shows a cross section along C 'of Figure 6. It appears that the pocket 20, the radial outlet area 40 and the outlet orifice 3 belong to the same cross section.

Finally, FIG. 10, concerning the section D ′ rather shows the bottom 25, 25 ′ of each channel, bottom in the form of a hairpin.

This geometry will preferably be adopted when better aerodynamics of the internal channel and / or better flow are sought.

Claims (6)

1. Essentially cylindrical rotary valve designed for the admission of a fluid into a combustion chamber of an internal combustion engine, having at least one bent internal flow passage (1, 1') for the fluid, each passage having an inlet orifice (2, 2') located on the side wall of the said valve, an outlet orifice (3, 3') arranged in the cylindrical surface of the said valve, and a bend (20, 20) designed to retain the heaviest elements of the fluid under the effect of centrifugal force, the thickness (21, 21') of the wall of the valve between the external face of the passage and the exterior of the valve being relatively thin at the level of the bend (20, 20'), characterised in that at least one of the outlet orifices (3, 3') of at least one of the said passages and at least one of the said bends (20, 20') are in a same transversal section of the valve.
2. Rotary valve as claimed in claim 1, characterised in that at least one of the said bends (20, 20') of at least one of the said passages is located such that its upper surface faces the inlet orifice of the cylinder head during the combustion phase.
3. Rotary valve as claimed in one of claims 1 or 2, characterised in that the profile of each passage (1, 1') is such that the fluid initially moves through the valve substantially longitudinally before being discharged in a substantially radial direction.
4. Rotary valve as claimed in any one of the previous claims, characterised in that each passage has two bends (25, 35) in succession, the first (25) to reverse the essentially longitudinal direction of flow, the second bend (35) designed to produce a substantially radial flow at the outlet.
5. Rotary valve as claimed in any one of the previous claims, characterised in that the rotary valve has two passages (1, 1') arranged symmetrically relative to an axial plane.
6. Rotary valve as claimed in any one of the previous claims, characterised in that the zone of the passage located close to the inlet (3) of the passage has at least one face that is sharply inclined in order to direct the mixture efficiently towards the interior of the valve.

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