SEQUENTIAL VOLUMETRIC FLOWMETER

The sequential volumetric flowmeter includes a static measurement enclosure which is connected to a fluid inlet duct and a fluid outlet duct and in which a movable separator can move to form a variable input volume and a variable output volume, a mobile return spring tending to reduce the variable input volume, the minimum volume of which is fixed by a start-of-stroke static stop and a movable start-of-stroke stop; a bypass valve controlled by a valve actuator can put the variable input volume in communication with the variable output volume, and a displacement measurement unit informing a computer about the position of the movable separator.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a sequential volumetric flowmeter, particularly provided to precisely measure the volume and/or mass flow of a gas, over a large amplitude.

Description of the Related Art

Said flowmeter according to the present invention is particularly suitable for the implementation of the valve ignition pre-chamber which was the subject of patent No. FR 3,061,743 published on Aug. 16, 2019, said patent belonging to the applicant.

Said pre-chamber provides in particular that a pilot charge is injected into a stratification cavity by a stratification injector, said charge consisting of an easily flammable air-fuel mixture previously pressurized by compression means.

The invention according to patent FR 3,061,743 is particularly intended for the automotive market. However, said market is very sensitive to costs, weight and size of any equipment, which must remain as low as possible. The automotive market is also very demanding in terms of robustness, reliability, service life, and maintenance.

The valve ignition pre-chamber according to patent FR 3,061,743 relates to this context, said pre-chamber requiring both high flow metering precision of the air-fuel mixture which constitutes the pilot charge, and great control over the amount of pilot charge injected into the stratification cavity at each cycle.

To achieve said precision and control, it is necessary to know precisely the mass flow rate of air introduced into the stratification cavity by the stratification injector. This information is necessary for, firstly, adding to said air the quantity of fuel necessary in order to obtain the desired air/fuel ratio for the pilot charge, and secondly, to control the stratification injector so that the latter introduces effectively the quantity of mixture sought in the stratification cavity.

Implementing the valve ignition pre-chamber according to patent FR 3,061,743 therefore requires the availability of an air mass flowmeter meeting all the requirements associated with this application.

It is to be noted that many types of flowmeter exist, being either a flowmeter with depressogenic member, a Pitot tube, ludion, cup, propeller or turbine flowmeter, a vane, ionic, ultrasonic, electromagnetic flowmeter, a Coriolis effect, Karman vortex or vortex effect flowmeter, a hot wire or film flowmeter, or thermal mass flowmeter.

Among the embodiments of flowmeters known to those skilled in the art are also the volumetric flowmeters, which alternately fill and empty with the fluid to be measured, said flowmeters possibly having a reciprocating, rotary or oscillating piston, or else with a membrane, a paddle or gears.

In addition to meeting the various requirements of the automotive industry, the flowmeter necessary for the implementation of the valve ignition pre-chamber according to patent FR 3,061,743 must be capable of precisely measuring the mass flow rate of the passing air over a large flow amplitude, which may vary by a factor of one hundred and fifty or more, which only very few flowmeters allow.

In addition, the flowmeter necessary for the implementation of said pre-chamber must be capable to operate under a relatively high pressure, of the order of fifty bars, and at variable temperature ranging from minus thirty degrees Celsius to over one hundred fifty degrees Celsius.

Finally, said flowmeter must be capable of withstanding the vibrations produced by a reciprocating internal combustion engine without damaging the accuracy and durability of said flowmeter. As previously mentioned, despite this set of requirements, said flowmeter must remain compact, reliable, robust and inexpensive.

SUMMARY OF THE INVENTION

It is therefore primarily to implement the valve ignition pre-chamber according to patent FR 3,061,743 that, according to a particular embodiment, the sequential volumetric flowmeter according to the invention:offers high precision in volume and mass flow measurement;measures flow over a min/max range of one to one hundred and fifty or more;can operate over a wide temperature range, compatible with the requirements of automotive engines;is insensitive to vibrations produced by a reciprocating internal combustion engine, said vibrations not affecting the measurement accuracy of said flowmeter;has a durability, robustness and reliability compatible with the automotive industry;requires no special maintenance;is lightweight and compact.

It is to be understood that the sequential volumetric flowmeter according to the invention can be applied not only to the valve ignition pre-chamber according to patent FR 3,061,743, but also to any other application, whatever the type or field, which requires an accurate measurement of the volumetric and/or mass flow rate of a gas or a liquid.

The sequential volumetric flowmeter according to the present invention is provided for measuring the flow rate of a fluid, said flowmeter comprising:A static measurement enclosure connected, on the one hand, to a fluid inlet duct through which the fluid enters said enclosure, and, on the other hand, to a fluid outlet duct through which the fluid exits said enclosure;At least one movable separator which can move in a sealed manner inside the static measurement enclosure, one surface located on the input volume side of said separator forming with said enclosure a variable input volume connected to the fluid inlet duct, and one surface located on the output volume side of said separator forming with said enclosure a variable output volume connected to the fluid outlet duct;At least one mobile return spring which bears directly or indirectly in the static measurement enclosure to push or pull the movable separator in the direction of the variable input volume, said spring tending, on the one hand, to reduce the internal volume of the variable input volume and, on the other hand, to increase the pressure of the fluid contained in said volume;At least one start-of-stroke static stop fixed with respect to the static measurement enclosure, said stop being capable to come into contact with a movable start-of-stroke stop fixed with respect to the movable separator, the two stops defining the minimum volume of the variable input volume when they are in contact with one another;At least one bypass valve, the opening of which is controlled by a valve actuator, said valve putting directly or indirectly, when it is open, the variable input volume in communication with the variable output volume via a transfer channel;Displacement measurement means which provide information to a computer about the position of the movable separator relative to the static measurement enclosure.The sequential volumetric flowmeter according to the present invention comprises a movable separator which consists of a separating piston which moves in a separator cylinder which is formed by the inside of the static measurement enclosure, piston sealing means providing a seal between said piston and said cylinder.The sequential volumetric flowmeter according to the present invention comprises piston sealing means which consists of a flexible diaphragm.The sequential volumetric flowmeter according to the present invention comprises a movable separator which consists of a separation gaiter, one end of which being fixed in a sealed manner inside the static measurement enclosure, and the other end of which being sealed by a movable spring cup on which bears the mobile return spring.The sequential volumetric flowmeter according to the present invention comprises a bypass valve which includes a bypass flap which can rest in a sealed manner on a flap seat formed in the variable input volume and fixed with respect to the static measurement enclosure, said flap being capable to move away from said seat by moving towards the interior of the variable input volume, whereas, when said flap rests on said seat, its face oriented towards the variable input volume forms the start-of-stroke static stop.

The sequential volumetric flowmeter according to the present invention comprises a bypass flap which has a flap opening movable stop which is capable to come into contact with a flap opening fixed stop fixed with respect to the static measurement enclosure, the two stops determining, when they are in contact with each other, the maximum distance which can separate the bypass flap from the flap seat with which it cooperates.

The sequential volumetric flowmeter according to the present invention comprises a flap spring which tends to move the bypass flap away from the flap seat with which it cooperates, the force produced by said spring being less than the force exerted on the bypass flap by the pressure of the fluid contained in the variable input volume when, on the one hand, said flap rests on said seat, and that, on the other hand, said pressure is greater than that of the fluid contained in the variable output volume as a result of the force exerted by the mobile return spring on the movable separator.

The sequential volumetric flowmeter according to the present invention comprises a valve actuator which consists of a magnetizable metal member which is mechanically connected to the bypass flap, said member being capable of imparting movement to said flap when it is attracted by a magnetic field produced by an actuator coil when the latter is traversed by an electric current.

The sequential volumetric flowmeter according to the present invention comprises a valve actuator which consists of a lifting linkage mechanically connected to the movable separator, said linkage having at least one actuator lifting stop which, firstly, contacts a flap lift stop fixed with respect to the bypass flap when the variable input volume has reached a predetermined volume and which then moves said flap away from the flap seat with which it cooperates as a result of the movement of the movable separator.

The sequential volumetric flowmeter according to the present invention comprises a transfer channel which is closed by a retaining flap held in contact with a retaining seat by a retaining spring, the latter letting said flap move away from said seat and open said channel only as from a determined pressure, so that the fluid coming from the variable input volume circulates in said channel while, at the same time, a retaining nozzle allows said fluid to pass through said channel even when the retaining flap is in contact with the retaining seat.

The sequential volumetric flowmeter according to the present invention comprises displacement measurement means which consist of a measurement rack which is fixed with respect to the movable separator and which, when moving with said separator, rotatably drives a measurement pinion which in turn rotatably drives, directly or by means of a mechanical multiplier, an impulse wheel fitted on its periphery with regularly distributed impulse generators, said wheel cooperating with impulse sensing means fixed with respect to the static measurement enclosure and in front of which the impulse generators pass, said sensing means transforming the passage of each impulse generator into an electrical signal transmitted to the computer.

The sequential volumetric flowmeter according to the present invention comprises a measurement pinion which drives the impulse wheel via a freewheel.

The sequential volumetric flowmeter according to the present invention comprises an impulse wheel which is connected to the static measurement enclosure via a freewheel.

The sequential volumetric flowmeter according to the present invention comprises a measurement pinion which drives, in addition to the impulse wheel and by means of a balancing rack, a balancing mass in longitudinal translation opposite the direction of the movement of the movable separator which takes place simultaneously, the relative speed and weight of said mass and of said rack being calculated so that when said mass and said rack move, they produce inertia forces of the same intensity as those produced at the same time by said separator and the measurement rack with which it cooperates.

The sequential volumetric flowmeter according to the present invention comprises displacement measurement means consisting of an impulse spindle which is provided with impulse generators along its length, and which is fixed with respect to the movable separator so that when said spindle moves with said separator, the impulse generators passing in front of impulse capture means which are fixed with respect to the static measurement enclosure and which transform the passage of each impulse generator into an electrical signal transmitted to the computer.

The sequential volumetric flowmeter according to the present invention comprises displacement measurement means consisting of a separator end-of-stroke sensor which is fixed with respect to the static measurement enclosure or to the moveable separator, said sensor transmitting an electrical signal to the computer when the variable input volume reaches a predefined maximum magnitude.

The sequential volumetric flowmeter according to the present invention comprises a movable separator which is directly or indirectly connected to the static measurement enclosure by a separator damper.

The sequential volumetric flowmeter according to the present invention comprises a pressure sensor and/or a temperature sensor which directly or indirectly measures the pressure and/or temperature prevailing in the variable input volume and/or the variable output volume.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The sequential volumetric flowmeter1according to the invention, various details of its components, variants, and accessories are shown inFIGS. 1 to 10. Said flowmeter1is provided for measuring the flow rate of a fluid2.

As shown inFIGS. 1 to 10, the sequential volumetric flowmeter1according to the invention comprises a static measurement enclosure3connected, on the one hand, to a fluid inlet duct4through which the fluid2enters said enclosure3, and, on the other hand, to a fluid outlet duct5through which the fluid2leaves said enclosure3.

The sequential volumetric flowmeter1also comprises at least one movable separator6which can move in a sealed manner inside the static measurement enclosure3, a surface on the input volume side7of said separator6forming with said enclosure3a variable input volume8connected to the fluid inlet duct4, and a surface on the output volume side9of said separator6forms with said enclosure3a variable output volume10connected to the fluid outlet duct5.

It is to be noted that the movable separator6may in particular be a bladder, a bag or any other deformable container capable of storing fluid2.

FIGS. 1 to 10also show that the sequential volumetric flowmeter1according to the invention comprises at least one mobile return spring11which is directly or indirectly supported in the static measurement enclosure3to push or pull the movable separator6in the direction of the variable input volume8.

The mobile return spring11tends, on the one hand, to reduce the internal volume of the variable input volume8and, on the other hand, to increase the pressure of the fluid2contained in said volume8; said spring11can be helical, multi-turn corrugated, made up of a stack of elastic washers, or be of any type whatsoever known to those skilled in the art.

As can be seen inFIGS. 1 to 10, the sequential volumetric flowmeter1according to the invention further comprises at least one start-of-stroke static stop12fixed with respect to the static measurement enclosure3, said stop12being capable to contact a movable start-of-stroke stop13fixed with respect to the movable separator6, said two stops12,13defining the minimum volume of the variable input volume8when they are in contact with one another.

Said flowmeter1also comprises at least one bypass valve14whose opening is controlled by a valve actuator17, said valve14putting directly or indirectly, when it is open, the variable input volume8in communication with the output variable volume10via a transfer channel59.

It is to be noted that the valve actuator17can be mechanical, electrical, electromagnetic, pneumatic, hydro-mechanical, piezoelectric, and in general, of any type known to those skilled in the art.

InFIGS. 1 to 10, are also shown the displacement measurement means15that comprises the sequential volumetric flowmeter1according to the invention, said means15providing information to a computer16about the position of the movable separator6with respect to the static measurement enclosure3.

It should be noted that the displacement measurement means15may consist of any displacement, distance or position sensor, whether said sensor is of the absolute or incremental, resistive, potentiometric, capacitive, inductive, magneto-inductive type, eddy current type, laser-type optic or not, taut wire-type, and in general, of any type known to those skilled in the art.

It is also understood that the computer16can be more or less complex and that it can as such consist either of simple electrical components, or of sophisticated electronic and computer technologies, or of both.

It has been shown inFIGS. 1 to 6that according to a particular embodiment of the sequential volumetric flowmeter1according to the invention, the movable separator6may consist of a separating piston18which moves in a separator cylinder19that forms the inside of the static measurement enclosure3, piston sealing means20providing a seal between said piston18and said cylinder19.

As seen inFIGS. 4 to 6, the piston sealing means20may for example consist of at least one seal21made of one or more elastomer and/or metal parts.

InFIGS. 1 to 3, it has also been shown that the piston sealing means20may consist of a flexible diaphragm22like those included in automotive brake assist master cylinders.

FIGS. 7 to 10show that the movable separator6can consist of a separation gaiter23, a first end of which is fixed in a sealed manner inside the static measurement enclosure3, and the other end of which is sealed by a movable spring cup24on which the mobile return spring11bears.

It is to be noted that, as shown inFIGS. 7 to 10, one or more gaiter retaining rings25may be provided between the folds of the separation gaiter23, said rings25preventing the gaiter23from inflating excessively under the effect of pressure.

FIGS. 1 to 10show that according to an embodiment of the sequential volumetric flowmeter1according to the invention, the bypass valve14can include a bypass flap26which can sealingly bear on a flap seat27formed in the variable input volume8and fixed with respect to the static measurement enclosure3, said flap26being capable to move away from said seat27by moving towards the inside of the variable input volume8, whereas, when said flap26rests on said seat27, the face of said flap26facing towards the variable input volume8forms the start-of-stroke static stop12.

As a non-represented technological equivalent, it is to be noted that the bypass flap26can be fixed with respect to the movable separator6and rest in a sealed manner on a flap seat27fitted on the face located on the input volume side7, said flap26forming, in this case, the start-of-stroke movable stop13.

FIGS. 1 to 8 and 10show that the flap seat27can expose an elastomeric ring29on which the bypass flap26can rest without impact, and as tightly as possible.

As shown inFIGS. 1 to 10, the bypass flap26may advantageously have a flap opening movable stop35which is capable to come into contact with a flap opening fixed stop36fixed with respect to the static measurement enclosure3, the two stops35,36determining, when they are in contact with each other, the maximum distance that can separate the bypass flap26from the flap seat27with which it cooperates.

It is also to be noted inFIGS. 1 to 10that the sequential volumetric flowmeter1according to the invention may include a flap spring28which tends to move the bypass flap26away from the flap seat27with which it cooperates, the force produced by said spring28being less than the force exerted on the bypass flap26by the pressure of the fluid2contained in the variable input volume8when, on the one hand, said flap26rests on said seat27, and that, on the other hand, this pressure is higher than that of fluid2contained in the variable output volume10as a result of the force exerted by the mobile return spring11on the movable separator6.

As shown inFIGS. 1 to 3andFIGS. 7, 8 and 10, the valve actuator17may consist of a magnetisable metal member30which is mechanically connected to the bypass flap26, said member30being capable of imparting movement to said flap26when it is attracted by a magnetic field produced by an actuator coil31when the latter is traversed by an electric current controlled by the computer16.

FIGS. 4 to 6show another embodiment according to which the valve actuator17may consist of a lifting linkage32mechanically connected to the movable separator6, said linkage32having at least one actuator lifting stop33which, firstly, contacts a valve lifting stop34fixed with respect to the bypass flap26when the variable inlet volume8has reached a predetermined volume and which then moves said flap26away from the flap seat27with which it cooperates as a result of the movement of the movable separator6.

As illustrated inFIGS. 4 to 6, an unlocking spring50can advantageously be interposed between the actuator lifting stop33and the flap lift stop34, said spring50facilitating the detachment of the bypass flap26from the flap seat27with which it cooperates when said flap26is urged to open by the movable separator6.

As seen inFIGS. 4 to 6, the unlocking spring50can for example be configured as a spring washer known per se.

InFIGS. 4 to 6, it is also noted that the transfer channel59can be closed by a retaining flap51held in contact with a retaining seat52by a retaining spring53, the latter letting said flap51move away from said seat52and open said channel59only as from a determined pressure, so that the fluid2coming from the variable input volume8circulates in said channel59, while, at the same time, a retaining nozzle54allows said fluid2to pass through said channel59even when the retaining flap51is in contact with the retaining seat52.

As will be understood by examiningFIGS. 5 and 6, when the flap lift stop34begins to move the bypass flap26away from the flap seat27, the retaining flap51allows a rapid pressure rise of the fluid2downstream of the bypass flap26, which allows the flap spring28to detach said flap26from the flap seat27with which it cooperates.

When the start-of-stroke movable stop13presses again the bypass flap26on its flap seat27, the retaining nozzle54depressurizes the volume located immediately downstream of the bypass flap26so as to ensure maintaining said flap26on said seat27.

It is to be noted that if the valve actuator17is electric, pneumatic or of any type whatsoever, the retaining flap51prevents the bypass flap26from closing prematurely under the effect of the rapid movement of the fluid2in the transfer channel59when the movable separator6moves in the direction of the variable input volume8under the action of the mobile return spring11.

As a particular embodiment of the sequential volumetric flowmeter1according to the invention, it is to be noted inFIGS. 7 to 10that the displacement measurement means15may consist of a measurement rack37which is fixed with respect to the moveable separator6and which, when it moves with said separator6, rotatably drives a measurement pinion38which in turn rotatably drives, directly or by means of a mechanical multiplier44, an impulse wheel39fitted on its periphery with regularly distributed impulse generators40.

In this case, the impulse wheel39cooperates with impulse sensing means41fixed with respect to the static measurement enclosure3and in front of which the impulse generators40pass, said sensing means41transforming the passage of each impulse generator40into an electrical signal transmitted to the computer16.

It is to be noted that the impulse capture means41may for example consist of a light source received by a photosensitive sensor, the reception of light by said sensor being interrupted by the passage of the impulse generators40between said source and said sensor.

As a non-limiting embodiment shown inFIGS. 9 and 10, the impulse capture means41may consist of a “Hall” effect sensor42known per se, the impulse generators40being configured as impulse slots43which pass in front of said sensor.

It is to be noted that the measurement rack37and the measurement pinion38can be replaced by any other mechanical connection which can transform a linear movement into a rotational movement such as for example a cable which winds around a pulley, or a reversible wide-pitch screw which cooperates with a complementary internal thread, said screw and said internal thread being capable to come into contact with one another by means of circulating balls.

It is also to be noted that the mechanical multiplier44can consist of a succession of pinions as shown inFIGS. 7 to 10, of friction wheels, of one or more epicyclic gears, of a succession of toothed pulleys of different diameters connected by toothed belts, or any other type of mechanical multiplier44known to those skilled in the art.

Advantageously, the measurement pinion38and the pinion or pinions which may constitute the mechanical multiplier44may be provided with a play readjustment device known per se.

According to a particular embodiment of the sequential volumetric flowmeter1according to the invention, the measurement rack37, the measurement pinion38, the impulse wheel39, the accessories thereof, and all or part of the impulse capture means41may be housed within the variable output volume10, so that no sealed mobile connection is required between these various components37,38,39,41and the inside of the output variable volume10.

In this case, in order to partially occupy the empty space remaining in the variable output volume10and/or the variable input volume8, one or more incompressible polymorphic parts may be housed in said volume10,8which more or less accurately conform to said various components37,38,39,41by touching or not touching the latter and in any case, without interfering with the proper functioning of the latter.

As clearly shown inFIG. 7, it is to be noted that the measurement pinion38can drive the impulse wheel39via a freewheel45which allows the pinion38to drive the impulse wheel39when the variable input volume8increases due to the displacement of the movable separator6, but not when said volume8decreases.

According to this particular configuration, It may also be provided that the impulse wheel39is connected to the measurement static enclosure3by means of a freewheel45which allows the measurement wheel39to rotate in the direction of rotation imparted to it by the measurement pinion38, but which prevents said wheel39to turn in the opposite direction.

It is to be noted that, as an alternative, this freewheel45can be replaced by a non-represented brake, the latter may also be advantageously added to said wheel45to prevent the rotational inertia of the impulse wheel39from being unduly interpreted by the computer16as a continuity of fluid flow2through the volumetric flowmeter sequential1according to the invention, even though said flow would have suddenly dropped, or even would have suddenly stopped.

According to another embodiment, a flywheel can be associated with the impulse wheel39either by directly weighting the latter or by connecting it to the flywheel by any mechanical link whatsoever.

Another embodiment of the sequential volumetric flowmeter1according to the invention shown inFIGS. 7 to 10consists in the measurement pinion38driving, in addition to the impulse wheel39and by means of a balancing rack47, a balancing mass46in longitudinal translation opposite the direction of the movement of the movable separator6which takes place simultaneously, the relative speed and weight of said mass46and said rack47being calculated so that when said mass46and the rack47move, they produce inertia forces of the same intensity as those produced at the same time by said separator6and the measurement rack37with which it cooperates.

This particular configuration of the sequential volumetric flowmeter1according to the invention makes it possible to make said flowmeter1insensitive to vibrations, for example when the latter is secured to a thermal internal combustion engine.

Indeed, the balancing mass46prevents the movable separator6from inadvertently moving relative to the static measurement enclosure3under the effect of said vibrations, which would have the consequence of making the flow reading of fluid2by the computer16false, or even impossible.

FIGS. 1 to 3show that the displacement measurement means15can also consist of an impulse spindle55which is provided along its length with impulse generators40, and which is fixed with respect to the movable separator6, so that when said spindle55moves with said separator6, the impulse generators40passing in front of impulse capture means41which are fixed with respect to the static measurement enclosure3and which transform the passage of each impulse generator40into an electrical signal transmitted to the computer16.

As an alternative, the impulse spindle55may be fixed with respect to the static measurement enclosure3and the impulse capture means41be fixed with respect to the movable separator6.

InFIGS. 1 to 3, it has been shown that the displacement measurement means15can consist of a separator end-of-stroke sensor56which is fixed with respect to the static measurement enclosure3or the movable separator6, said sensor56transmitting an electrical signal to the computer16when the variable input volume8reaches a predefined maximum magnitude.

It is to be noted that the separator end-of-stroke sensor56can be a proximity sensor known per se, regardless of the type or principle of operation.

Still inFIGS. 1 to 3, it has also been shown that the movable separator6can be directly or indirectly connected to the static measurement enclosure3by a separator damper57which prevents said separator6from being subjected to large amplitude oscillations when the sequential volumetric flowmeter1according to the invention is subjected to vibrations, for example if said flowmeter1is fixedly secured to a reciprocating internal combustion engine70.

As shown inFIGS. 1 to 3and as a particular configuration of the sequential volumetric flowmeter1according to the invention, a pressure sensor48and/or a temperature sensor49can directly or indirectly measure the pressure and/or the temperature prevailing in the variable input volume8and/or the variable output volume10, said two sensors48,49allowing the computer16to determine the mass flow rate of the fluid2which passes through the sequential volumetric flowmeter1according to the invention from the information which is transmitted to said computer16by the displacement measurement means15, and taking into account the force exerted by the mobile return spring11on the movable separator6.

Operation of the Invention:

The operation of the sequential volumetric flowmeter1according to the invention is easily understood by studyingFIGS. 1 to 10, which show non-limiting embodiments of said flowmeter1.

To explain said operation and initially, reference is made here toFIGS. 1 to 3which show the sequential volumetric flowmeter1according to the invention as it can be used to implement the valve ignition pre-chamber77according to patent FR 3,061,743, on a reciprocating internal combustion engine70.

It is shown inFIGS. 1 to 3, and schematically, the reciprocating internal combustion engine70which receives said valve ignition pre-chamber77supplied with pilot charges73by a stratification injector80.

Said pilot charges73are, by way of non-limiting example, formed of an easily flammable gas mixture consisting of a proportion of fourteen grams of air78per gram of gasoline79.

This gas mixture is therefore slightly rich compared to stoichiometry, and is made in an air-gasoline74mixer fed, on the one hand, with gasoline79under a pressure of forty bars, from a fuel tank71via a fuel pump72, and, on the other hand, with atmospheric air78by an air compressor75via an air filter81, the inlet pressure of that compressor75being regulated by a throttle casing82.

The air-gasoline mixer74produces a homogeneous mixture of said air78and said gasoline79, the latter having to remain entirely in the gaseous state despite the pressure of forty bars to which it is subjected.

It should be noted that an air-gasoline mixer74fulfilling all the functions necessary to supply the pilot charge73of the valve ignition pre-chamber77according to the patent FR 3,061,743 was the subject-matter of patent application FR 2004269, filed on Apr. 29, 2020 by the Applicant, titled “Forced Recirculation Mixer”.

InFIGS. 1 to 3, can be noted the presence of a computer16in particular for controlling the stratification injector80, the different functions of the air-gasoline mixer74, and the throttle casing82.

The throttle casing82makes it possible to maintain the pressure of forty bars downstream of compressor75regardless of the speed and load of the reciprocating internal combustion engine70, and regardless of the amount of pilot charge73introduced by the stratification injector80into the valve ignition pre-chamber77at each thermodynamic cycle of said engine70.

FIGS. 1 to 3also show a pressure sensor48and a temperature sensor49which, respectively, transmit to computerl6the pressure and temperature of air78found at the inlet of the liquid inlet duct4of the sequential volumetric flowmeter1according to the invention.

According to the particular embodiment of this flowmeter1shown inFIGS. 1 to 3, the movable separator6consists of a separating piston18which moves in a separator cylinder19which is formed by the inside of the static measurement enclosure3.

FIGS. 1 to 3also show the mobile return spring11, which bears in the static measurement enclosure3so as to push the separating piston18in the direction of the variable input volume8, said spring11tending to increase the pressure of the fluid2contained in said volume8.

FIGS. 1 to 3show that the piston sealing means20which provide a seal between the separating piston18and the cylinder separator19consist of a flexible diaphragm22similar to those of the automotive brake assist master-cylinders.

InFIGS. 1 to 3, It is also to be noted that the separating piston18is connected to the static measurement enclosure3by a separator damper57which prevents said piston18from being subjected to parasitic oscillations capable of distorting the air flow measurement78by the sequential volumetric flowmeter1when the reciprocating internal combustion engine70transmits vibrations to it.

It can be seen inFIGS. 1 to 3that the displacement measurement means15consist in particular of an impulse spindle55provided over its length with impulse generators40. Said spindle55is fixed with respect to the separating piston18so that when the latter moves relative to the static measurement enclosure3, the impulse generators40pass one after the other in front of a “Hall” effect sensor42fixed with respect to said enclosure3, said sensor42transforming the passage of each impulse generator40into an electrical signal which is transmitted to the computer16.

In addition to said impulse spindle55, it can be seen inFIGS. 1 to 3that the displacement measurement means15includes a separator end-of-stroke sensor56fixed with respect to the static measurement enclosure3.

When the impulse spindle55approaches said sensor56at a distance, for example less than one millimeter, said sensor56provides the related information to the computer16by means of an electrical signal.

According to the particular embodiment of the sequential volumetric flowmeter1according to the invention shown inFIGS. 1 to 3, the bypass valve14comprises a bypass flap26which can sealingly rest on a flap seat27, the latter being arranged in the variable input volume8and fixed with respect to the static measurement enclosure3.

It is to be noted that the bypass flap26can move away from the flap seat27by moving towards the inside of the variable input volume8, and this as long as it is not stopped along its movement by the flap opening movable stop35which said flap26has.

It is to be noted that the flap opening movable stop35cooperates with a flap opening fixed stop36fixed with respect to the static measurement enclosure3, said two stops35,36determining, when they are in contact from each other, the maximum distance that can separate the bypass flap26from the flap seat27.

It is also to be noted that when the bypass flap26rests on the flap seat27, its face oriented towards the variable input volume8forms a start-of-stroke static stop12which cooperates with a start-of-stroke movable stop13fixed with respect to the separating piston18, said two stops12,13defining the minimum volume of the variable input volume8when they are in contact with one another.

It is to be noted that the lifting of the bypass flap26from the flap seat27on which it rests is done by means of a valve actuator17.

Said actuator17is here and as a non-imitative example consisting of a magnetisable metal member30which, inFIGS. 1 to 3, is configured as a magnetic pallet83mechanically connected to the bypass flap26.

The magnetic pallet83can thus lift the bypass flap26from the seat27on which it rests, which happens when said pallet83is attracted by the magnetic field produced by an actuator coil31when the latter is crossed by an electric current controlled by the computer16.

InFIG. 1is depicted the sequential volumetric flowmeter1according to the invention in the filling phase of the variable input volume filling8.

During this filling phase, the air78discharged from the air compressor75is introduced into the variable input volume8by the fluid inlet duct4.

Provided the bypass flap26rests on its flap seat27, the introduction of air78through the fluid inlet duct4causes the separating piston18to go back and the variable input volume8to increase.

At the same time, the variable output volume10decreases and expels the air78it contains through the fluid outlet duct5.

It should be noted that since the separating piston18is pushed in the direction of the variable input volume8by the mobile return spring11, the pressure prevailing in the variable input volume8is higher than that prevailing in the output variable volume10.

Due to the non-null stiffness of the mobile return spring11, the pressure difference between the variable input volume8and the variable output volume10is all the more important as said spring11is compressed.

We will assume here that the pressure difference is one hundred millibars at the beginning of the ascending stroke of the separating piston18, and two hundred millibars at the end of said stroke.

Throughout the ascending stroke of the separating piston18, the impulse generators40that the impulse spindle55has pass one after the other in front of the “Hall” effect sensor42, the latter transmitting the electrical signals corresponding to the computer16.

Knowing the time elapsed between two signals of passage of the impulse generator40, the computer16can calculate the volume flow rate of air78passing through the fluid inlet duct4, said flow rate being equal to the product of the section of separating piston18by the speed of said piston18.

To calculate the mass flow rate of air78passing through the fluid inlet duct4, the computer16takes into account the pressure and the temperature which are respectively transmitted to it by the pressure sensor48and the temperature sensor49. In fact, the mass flow rate of air78corresponds to the product of the volume flow rate of said air78by the density of said air78, the latter resulting from the product of the pressure of said air78by the temperature of said air78.

When the separating piston18reaches its top dead center, as shown inFIG. 2, the separator end-of-stroke sensor56sends an electrical signal to the computer16which triggers the opening of the bypass flap26by means of the actuator coil31.

It is to be noted that until now, the bypass flap26was kept pressed against the flap seat27with which it cooperates by the pressure prevailing in the variable input volume8which was always greater of one hundred to two hundred millibars than that prevailing in the variable output volume10.

In fact, said difference has hitherto applied over the entire surface included within the line of contact formed by the bypass flap26with the flap seat27, said difference exerting on said flap26a force greater than that exerted by the flap spring28which tends to move said flap26away from the flap seat27.

The separating piston18having reached its top dead center, when the bypass flap26is lifted and then moved away from its flap seat27by the actuator coil31, the pressure difference between the variable input volume8and the variable output volume10suddenly becomes small to the point that the flap spring28can hold the bypass flap26open throughout the descending stroke of the separating piston18.

When the separating piston18has reached its bottom dead center, as shown inFIG. 3, the movable start-of-stroke stop13which it has first came into contact with the start-of-stroke static stop12formed by the bypass flap26, then forced said flap26to return in contact with the flap seat27in a sealed manner.

The bypass flap26being again closed and sealed, a new cycle of measuring the volume flow of air78can resume, which leads again to the situation shown inFIG. 1.

It should be noted that the computer16can detect when the separating piston18has reached its bottom dead center, which occurs, on the one hand, after the triggering of the opening of the bypass flap26by said computer16by means of the actuator coil31, and, on the other hand, after the reception by the aforementioned computer16of temporally very close signals of the passage of the impulse generators40, said signals being sent to said computer16by the “Hall” effect sensor42.

The termination of these close signals may also coincide with the minimum pressure detected by the pressure sensor48. From this information, the computer16can exclude the descending stroke of the separating piston18from the air flow78calculation, and determine the average flow of the air78flowing through the sequential volumetric flowmeter1only from the signals40resulting of the passing of the impulse generators in front of the “Hall” sensor42, which are received during the ascending stroke of the separating piston18.

The exclusion of the descending stroke of the separating piston18from the calculation of the average flow of the air78by the computer16is always necessary regardless of the configuration of the sequential volumetric flowmeter1according to the invention, whether such exclusion is mechanical or performed by software.

It should be noted that this exclusion is easier to achieve when the measurement displacement means15consist, for example, of a potentiometric displacement sensor58as shown inFIGS. 4 to 6. Indeed, according to this particular configuration of the sequential volumetric flowmeter1according to the invention, the computer16is at any moment informed about the position of the separating piston18relative to that of the static measurement enclosure3.

FIGS. 4 to 6also show that the movable separator6is configured as a separating piston18which differs from that shown inFIGS. 1 to 3in that the piston sealing means20it has consist of a lip sealing gasket21, known per se. Said sealing gasket21, whether pre-lubricated or of the dry-operating type, induces in any cases friction losses due to its contact with the separator cylinder19and, as such, it fully or partly performs the function of separator damper57.

The particular embodiment of the sequential volumetric flowmeter1according to the invention shown inFIGS. 4 to 6further provides that the valve actuator17no longer consists of a magnetic pallet83attracted by an actuator coil31, but a lifting linkage32mechanically connected to the separating piston18.

The lifting linkage32has an actuator lifting stop33which initially comes into contact with a flap lift stop34fixed with respect to the bypass flap26when the separating piston18is close to its top dead center, and which, in a second time, moves said flap26away from the flap seat27with which it cooperates as a result of the displacement of the separating piston18up to its top dead center.

FIGS. 4 to 6also show the release spring50which is interposed between the actuator lifting stop33and the flap lift stop34and facilitates the detachment of the bypass flap26from the flap seat27when the flap26is caused to open by the separating piston18via said stops33,34.

FIGS. 4 to 6also show the retaining flap51located in the transfer channel59and kept in contact with a retaining seat52by a retaining spring53, the latter letting said flap51move away from said seat52and open said channel59only as from a determined pressure.

Thus, and as can be readily deduced fromFIGS. 5 and 6, when the valve lift stop34begins to move the bypass flap26away from the flap seat27, the flap51allows a rapid rise of the pressure of the air78located immediately downstream of the bypass flap26, which allows in any case the flap spring28to detach said flap26from the flap seat27with which it cooperates.

FIGS. 4 to 6also show that the retainer flap51is pierced so as to form a retainer nozzle54, which allows air78to pass through the transfer channel59even when the retainer flap51is in contact with the retainer seat52.

The retaining nozzle54makes it possible that when the start-of-stroke movable stop13presses again the bypass flap26on the flap seat27, the pressure in the volume immediately downstream of said flap26drops so that said flap26remains well pressed against the flap seat27when the separating piston18goes again in the ascending stroke.

Another embodiment of the sequential volumetric flowmeter1according to the invention is shown inFIGS. 7 to 10. In this embodiment, the movable separator6consists of a separation gaiter23, of which a first end is sealingly fixed inside the static measurement enclosure3, and the other end is sealingly closed by a mobile spring cup24on which the mobile return spring11bears.

According to the particular configuration shown inFIGS. 7 to 10, the displacement measurement means15consist of a measurement rack37which is fixed with respect to the movable spring cup24and which, when it moves with said cup24, rotatably drives a measurement pinion38which in turn rotatably drives and by means of a mechanical multiplier44an impulse wheel39provided at its periphery with regularly distributed impulse generators40.

As can be seen clearly on pages9and10, the impulse wheel39cooperates with a “Hall” effect sensor42which is fixed with respect to the static measurement enclosure3and in front of which the impulse generators40of said wheel39pass, said sensor42transforming the passage of each impulse generator40into an electrical signal transmitted to the computer16.

InFIG. 8, it can be clearly seen that the measurement pinion38drives the impulse wheel39via a freewheel45.

This first freewheel45allows on the one hand, the measurement pinion38to drive the impulse wheel39when the variable input volume8increases but not when said volume8decreases, and, on the other hand, to let the impulse wheel39continue to rotate on its momentum when the variable input volume8decreases rapidly following the opening of the bypass flap26.

InFIG. 8, it is to be noted that a second freewheel45connects the impulse wheel39to the static measurement enclosure3. Said second freewheel45allows the impulse wheel39to rotate in the direction of rotation that the measurement pinion38imparts on it, but prevents it from turning in the opposite direction.

The main advantage of the displacement measurement means15shown inFIGS. 7 to 10lies in the high precision in measuring the displacement of the movable separator6that they provide thanks to the mechanical multiplier44.

Indeed, said multiplier44and the freewheels45with which it cooperates allow the impulse wheel39to turn rapidly and to transmit to the “Hall” effect sensor42many impulses per unit of displacement of the movable separator6, and this without affecting the speed of return to bottom dead center of said separator6. Said high precision is obtained with simple and inexpensive mechanical and electronic means.

It is to be noted that regardless the embodiment used for the sequential volumetric flowmeter1according to the invention, its calibration can be carried out during its development, or apparatus by apparatus at the end of the process of manufacture, by means of a standard flowmeter. According to this method, it is possible to associate, with each effective flow rate recorded by the standard flowmeter, a behavior of the sequential volumetric flowmeter1according to the invention, and then to store the corresponding transfer rule in the computer16.

It should be noted that the examples of embodiments of the sequential volumetric flowmeter1according to the invention described above are not limitative.

It should also be noted that this flowmeter1according to the invention can be applied to fields other than that of internal combustion engines, such as chemistry, industrial processes or any apparatus in any field whatsoever that requires the measurement of the volume and/or mass flow rate of a fluid2, whatever is the nature of the fluid, and whatever is the liquid or gaseous state of the fluid.

The possibilities of the sequential volumetric flowmeter1according to the invention are not limited to the applications described above and it must be understood that the above description was given only as an example and that it does not limit the field in any way of said invention which would not be taken out by replacing the details of execution described by any other equivalent.