FR2753747A1 - ELECTRICALLY CONTROLLED VALVE WITH CONTINUOUS OPENING IN OPERATION, FOR REGENERATION OF A FUEL VAPOR COLLECTOR - Google Patents

Abstract

The valve has its valve (18) linked in movement to the core (20) of a solenoid, the coil (21) of which is supplied with modulated average current to modulate the distance between the valve (8) and a seat (17). Downstream of the seat (17), the valve communicates with an engine intake duct via a calibrator (16) with a constant flow section. Upstream of the seat (17), the valve is in communication with the canister. Modulating the force applied to the valve (18) makes it possible to modulate the pressure drop at the valve (18), and therefore the control pressure between the seat (17) and the calibrator (16), so as to modulate the flow bleed through this calibrator (16). Application of the electrically controlled valve with continuous opening in operation to the modulation of the continuous flow rate for purging the canisters of internal combustion engines.

Description

The invention relates to an electrically operated and opening valve.

  continuous in operation, for a circuit

  regeneration of a canister associated with a combustion engine

  internal tion, supplied with air or carburetted air by at least one intake duct, in which the flow rate is controlled by a throttling member, for example of the rotary type

commonly known as a butterfly.

  More specifically, the invention relates to a valve whose purge flow of the canister is continuous and modulated by an electrical signal, for the regeneration of a canister associated with an internal combustion engine including the fuel supply installation. can either include a carburetor, whose rotary throttle member, or throttle valve, controls the flow of air-fuel mixture, or be of the type called "injection" and include a throttle body, whose member throttling

  rotary controls the intake air flow to the engine.

  The canister is a receptacle collecting fuel vapors from various organs containing or traversed by fuel, in the circuit followed by the fuel in the vehicle and its engine, and in particular in the fuel tank, as well as the engine, and injection tubing and injector (s), or, if applicable

if applicable, from the carburetor.

  The canister, in which these fuel vapors are collected to avoid their rejection in the ambient air, is provided with a vent in communication with the atmosphere, so that the fuel tank is put in the open air through of the canister. To prevent fuel from being released into the open air through the canister vent, when the canister is saturated, the canister is cyclically regenerated by a circuit

  of regeneration including a valve mounted on a canali-

  station connecting the canister to the intake duct, downstream of the throttle member. When the valve is open, the vacuum downstream of the throttle member in the intake duct causes, in the pipe and in the canister, an aspiration of ambient air through the canister vent. This aspirated ambient air purges the canister of the fuel it contains and mixes with this fuel to be sucked with it into the intake duct. The arrival of this carburetted air in the engine modifies the richness of the air-fuel mixture prepared by the carburetor or the injector (s), depending on the case, which receives (s) orders from

  control developed from signals from different

  sensors for operating parameters of the engine, and in particular a probe measuring the oxygen level in

engine exhaust.

  To avoid this richness disturbance, it is known to use as a regeneration valve an electrically controlled valve ensuring a modulation of the canister purge flow, this flow being difficult to know because the load of fuel collected in the canisters is not not precisely known and depends on many parameters, such as the ambient temperature, the temperature and the conditions of filling the fuel tank, some of these parameters being able to be influenced by the

  engine running or not running.

  The electrically operated valves usually used for this purpose are solenoid valves comprising a calibrator with constant passage section and a check valve.

  flow control, linked in motion to a nucleus of a solenoid

  of, the coil of which is supplied with electric current with rectangular slots with variable opening cyclic ratio, that is to say that the opening time, for a constant period, corresponds to a variable fraction of this period, corresponding to the length of the niche of

current used.

  The variation of the flow rate is thus obtained by modulating the cross section of the calibration, subjected to the vacuum of the motor, this modulation being ensured by the valve of the solenoid valve. Given the frequencies, between 5 and Hz, at which these solenoid valves are energized, this results in an unbalanced supply of the different cylinders of the engine with fuel vapors from the purge of the canister, due to the opening frequency of the purge solenoid valve, which is completely asynchronous by

compared to the engine.

  To overcome this drawback, an electrically controlled valve has already been proposed in FR 2 699 603 making it possible to spread the regeneration flow so that all the engine cylinders receive substantially the same fraction of the canister purge fuel, this valve ensuring a continuous but modulated flow and slaved to an electrical set point signal, so as to obtain a flow valve proportional to this set point. This modulation of the canister purge flow is ensured by passing this flow through a calibrator with a constant passage section, but

  subjected to a modulated depression, unlike electro-

  previously used valves, in which the cross section of the calibration subjected to the engine vacuum is modulated. According to FR 2 699 603, the electrically controlled valve for a canister regeneration circuit of the type presented above, comprising a pipe connecting the canister to the intake duct, downstream of the throttle member, and on which is mounted the valve which includes a calibrator with constant passage section, a flow control valve in the pipeline and which is linked in movement to a core of a solenoid whose coil is supplied by an electric current to control

  the force on the valve, is such that the valve is soli-

  Daire in movement of a flexible membrane, which delimits, in a case, two chambers of which a first is maintained at

  a pressure close to or equal to atmospheric pressure

  that, and whose second chamber is modulated vacuum, contains the valve and placed in communication, by an inlet orifice, with the canister by means of the calibrator, and by an outlet orifice with the intake duct, the membrane thus subjected to a depression close to or equal to that which acts on the calibrator also being subjected to the opposing efforts of elastic means, which tend to close the valve on the outlet orifice, and of the solenoid,

  the coil of which develops a force having the effect of spreading

  ter the valve of the outlet orifice to open the latter, when it is traversed by a variable average current constituting an electrical reference signal fixing the force

on the valve.

  In operation, the membrane is in equilibrium under the combined actions of elastic means, which tend to recall the valve in the closed position, of the magnetic force due to the solenoid, and therefore of the current flowing through its coil, and finally of the vacuum. , which determines the flow rate, this depression being the differential pressure between atmospheric pressure or a pressure close to the latter and prevailing in the first chamber, and the control pressure in the second chamber. A relationship is thus established between this depression, and therefore the flow rate, on the one hand, and, on the other hand, the average electric current in the solenoid coil. This valve thus makes it possible to modulate the regeneration flow continuously by means of a variable vacuum determined at

  using an average control current.

  However, this valve has the disadvantage that at full opening, very large forces are exerted on the diaphragm, due to the high vacuum to which this diaphragm is then subjected (and which can reach kPa when the engine is running at idle) . The solenoid of this valve must therefore be capable of developing significant magnetic forces, at the cost of a significant

current consumption.

  By the present invention, it is proposed to remedy this drawback by means of a valve with continuous opening in operation, making it possible to avoid an unbalanced supply of the engine cylinders with fuel purged from the canister by a regeneration flow modulated in function of an electrical control signal, which is of a simpler and more economical structure, for mounting as for use, than the valve known by FR 2 699 603, and in particular which is satisfied with a solenoid weak

  dimensions, power and power consumption.

  For this purpose, the valve according to the invention, of a type known by FR 2 699 603, and which comprises a calibrator with constant passage section and a box delimiting a chamber placed in communication by an inlet with the canister and by a outlet with the intake duct, and in which a valve for controlling the canister purge flow rate is mounted movable relative to a seat which can be closed by the valve, which is linked in movement to a core of a solenoid whose coil is powered by a variable average electric current to control the force on the valve and its spacing from the seat in the valve open position, is characterized in that the outlet of the chamber is connected to the intake duct via of the calibrator so that the pressure downstream of the calibrator is

  the pressure in the duct downstream of the choke member-

  ment, while the inlet of the chamber is directly connected to the canister by the pipe, so that the upstream of the seat is at atmospheric pressure or at a pressure close to the latter, and the purge flow rate passing through the calibrator is continuously modulated by modulating the pressure difference at the valve resulting from

  the modulation of the force applied to the valve by the modula-

  tion of the variable mean current in the coil.

  As such a valve does not have a membrane and the section of its valve can be small, it is understood that a solenoid of small dimensions, low power and low consumption may be sufficient to control the valve valve, the structure of which can so be simpler

and more economical.

  Advantageously, in order to guarantee the closing of the valve when the engine is stopped, and to avoid any self-ignition phenomenon, the valve may further comprise elastic return means urging the valve towards its closed position against the seat, the power supply to the solenoid coil developing a magnetic force urging the valve against the elastic means by

seat open position.

  But it is also possible that the valve does not include elastic return means, and, in this case, when the engine is stopped, the solenoid coil is supplied by an electric current such that the valve is subjected to a magnetic force. applying it against his seat

  in the valve closed position.

  Such a valve is advantageously supplied with variable mean current obtained by supplying the coil of the

  solenoid by rectangular electrical current slots

  variable duty cycle areas. In addition, the variable mean current can be controlled by a control member sensitive to at least one signal from at least one sensor of an operating parameter of the engine, such as a richness sensor of the air-fuel mixture, and / or a pressure sensor in the downstream intake duct

of the throttling organ.

  Other advantages and characteristics of the invention

  tion will emerge from the description given below, at

  non-limiting title, of an exemplary embodiment described with reference to the accompanying drawings in which: - Figure 1 schematically shows a canister regeneration circuit, equipped with a valve according to the invention, and mounted between a canister and a conduit intake of a carburetor or throttle body of an internal combustion engine, and - Figure 2 is a schematic sectional view

  longitudinal view of an example valve.

  In FIG. 1, the canister 1 contains an absorbent or adsorbent material 2, for example activated carbon, which takes charge of the fuel vapors coming in particular from the fuel tank R, and which are brought to the canister 1 by the recovery line. 3. The canister 1, which can thus contain for example 100 g of fuel, is provided with a vent 4 connecting it to the atmosphere, and is also connected to the intake duct 5 of a carburetor body or a throttle body of an internal combustion engine M. A throttle or throttle member 6 is rotatably mounted in the duct 5, and the angular position of the throttle 6 in the duct 5 is controlled to regulate the intake flow d 'air, in the case of a throttle body, or carburetted air,

in the case of a carburetor.

  The connection of the canister 1 to the intake duct, downstream of the butterfly 6, is ensured by a circuit 7 for regenerating the canister 1. This circuit 7 comprises a regeneration line 8, which opens, at its entry, into the canister 1 , and, at its outlet, in the intake duct 5, as well as an electrically controlled valve 9, connected between the upstream 8a and downstream 8b branches of the

pipeline 8.

  The valve 9, an exemplary embodiment of which is shown in FIG. 2, is a gate valve whose position is controlled by a solenoid receiving a current

  electric control of a schematic control device

  only shown in 10, and which is an electronic engine control control unit, comprising a computer comprising at least one microprocessor or microcontroller,

  and in particular ensuring the control and command of the ignition

  mage and injection, in the case of an injection engine, from information received from several sensors

  engine operating parameters.

  When the valve 9 is open, the vacuum prevailing in the intake duct 5 downstream of the butterfly valve causes, through the pipe 8 and the canister 1, an aspiration of ambient air by the vent 4, and this air sucked entrained, passing through the material 2, the fuel previously retained in the latter, to introduce it into

the intake duct 5.

  In the example of FIG. 2, the valve 9 comprises a body or housing 11, of generally cylindrical shape, delimiting an internal chamber 12, which has an orifice

  inlet 13, connected to the upstream part 8a of the pipe-

  tion 8 of regeneration of the canister 1, as well as an outlet orifice 14, connected to the downstream part 8b of the pipeline 8 by a tubular end piece 15 containing a calibrator 16 or restriction, with a constant passage section. The periphery of the inlet orifice 13 constitutes a seat 17 for a valve 18. This valve 18 is in one piece, by a rod 19, with the core 20, substantially cylindrical, of a solenoid comprising a coil d excitation 21 fixed in the chamber 12 of the body 11, and in which are axially

engaged the core 20 and the rod 19.

  To avoid any phenomenon of auto-ignition by the untimely arrival of fuel coming from the canister 1

  in the engine M which is still warm, after stopping its function

  valve, the valve 9 is normally closed when the engine M stops. This closing is ensured, in this example, by a helical return spring 22, bearing on the valve 18 and on a support of the coil 21, and surrounding the part of the rod 19 located between the coil 21 and the valve 18, to push the valve 18 towards its seat 17, so as to close the inlet orifice 13 when the coil 21 is not supplied. The one-piece valve 18-stem 19-core assembly, the coil 21, the inlet port 13 and the seat 17 as well as optionally the outlet port 14 are, to ensure

  better mechanical behavior of the valve assembly

  core 20, preferably coaxial with the longitudinal axis of the

housing 11 and its chamber.

  In operation, the coil 21 is traversed by an average electric control current, which results from the supply of rectangular slots of current with variable duty cycle. The valve 18-core assembly 20 is then subjected to an electromagnetic force Fm, which separates the valve 18 from its seat 17 and from the inlet orifice 13, against the spring 22 exerting a restoring force Fr. The chamber 12 is then in communication with the upstream pipe 8a and the canister 1 via the inlet 13 and through the outlet 14 with the intake duct 5, through the calibrator 16. The pressure in the chamber 12 is a pressure of control or command Pc which is then intermediate between

  the pressure of the canister Pcan, upstream of the inlet 13, it

  even close to atmospheric pressure Pa, and the pressure downstream of calibrator 16, which is the pressure at the intake manifold of engine M, that is to say the prevailing pressure

  in the intake duct 5, downstream of the butterfly 6.

  The regeneration rate Q passing through the calibrator 16 is a function of Sc, p. Pc and Pcol according to a formula F1 (Sc, p. Pc, Pcol) which is tabulated in the control unit 10, and o Sc is the constant passage section of the calibrator 16, p the density of the air-fuel mixture coming from of the canister 1, and Pcol and Pc are respectively the manifold pressure, in the duct 5 downstream of the butterfly 6, and the control pressure in the chamber 12, the manifold pressure being known by the installation, since it is transmitted to the unit control unit 10 by a

  pressure 23, detecting the pressure in the inlet duct

sion 5 downstream of the butterfly 6.

  The control pressure Pc is equal to the pressure

  prevailing in the upstream part 8a of the pipe 8, that is

  & - say the pressure Pcan of the canister 1 or the pressure Pr of the tank R, minus the pressure difference or pressure drop at the level of the valve 18, which can be written by the formula (2): (2) Pc = Pcan - Ap,

  o Ap expresses the pressure drop due to valve 18.

  We know that the pressure Pcan at canister 1 is

  equal to or little different from atmospheric pressure Pa.

  We can therefore replace Pcan by Pa in formula (2).

  Furthermore, it is known that the pressure drop Ap at the level of the valve 18 is equal to the force applied to the valve 18, divided by the section s of the valve 18. As the force which urges the valve 18 is the difference between the magnetic force Fm, exerted on the core 20 by the current supply of the coil 21 of the solenoid, and the restoring force Fr exerted by the spring 22 on the valve 18, we obtain

  that the pressure drop Ap is given by formula (3) above

below: (3) Ap = Fm - Fr s

  where s is the section, which may be small, of the valve 18.

  In addition, the magnetic force Fm is a direct function of the average current flowing through the coil 21 of the solenoid. This magnetic force is therefore expressed by a function of this current I according to formula (4): (4) Fm = f (I) By replacing Fm by f (I) in formula (3), then by replacing Ap in formula (2) as a function of formula (3), and finally by replacing Pc in formula (F1)

  depending on its value given by formula (2), we obtain

  holds that the purge flow is expressed by the formula (5): (5) Q = F1 (Sc, p, Pcol, Pa, f (I) - Fr so Sc and s are constants, p is assimilated to a constant , Fr is known by construction of the spring 22, Pcol is known thanks to the measurement provided by the pressure sensor 23, and the atmospheric pressure Pa is also known, and can be measured as being the pressure in the intake duct 5, when the engine M stops, and therefore

  measured using the pressure sensor 23 before starting

engine rage.

  it can be seen that the flow rate Q is a function of the average current I flowing through the solenoid coil 21, the relation of formula (4) being a known characteristic

solenoid 20-21.

  As a result, the relationship between the purge flow rate Q and the average current I flowing in the coil 21 can be calculated or tabulated in memory in the unit of

control 10.

  The average current I applied to the coil 21 is obtained by a variable duty cycle control, at a

  sufficiently high frequency, around 100 Hz for example.

  It is thus possible to control a continuous purge flow rate Q, by acting on the duty cycle of the electrical supply of the

valve solenoid 9.

  The operating principle is therefore based on the regulation of the pressure drop or pressure difference at the level of the valve 18, and not of a variable section, to modulate the purge flow according to the needs, and taking particular account of the pressure Pcol at the intake manifold of the engine M. The purge flow Q of the canister 1, delivered by the valve 9, is continuous and modulated by the modulation of the electromagnetic force Fm, itself a function of the average control current I of the coil 21. The valve 9 is thus at flow

  continuous and modulated by the electric control current.

  So that this valve 9 is relatively insensitive to the vibrations of the motor M, a threshold spring 22 is chosen.

  low effort, but sufficient for this purpose.

  As a variant, the valve 9 can be without spring 22, in which case the coil 21 remains supplied, after the engine has stopped, for a sufficient time and in a direction suitable for maintaining the valve 18 against the seat by magnetic force. 17 in the closed position of the inlet 13 of the body 11. In a variant also, the valve 18 can cooperate with a seat 17 formed around the outlet orifice 14 of the chamber 12, in which case the control pressure Pc considered is the pressure in the

  tubular section 15 between the calibrator 16 and the outlet 14.

  It is also possible that the valve 18 is not directly integral in movement with the core 20, as is ensured by making a single piece of the valve 18 with the core 20 by the rod 19, and the valve 18 can be linked in motion at the core 20 by means of reduction of the amplitude of displacement of the valve 18

  relative to the amplitude of displacement of the core 20.

  In all these embodiments, a valve is obtained which makes it possible to modulate the regeneration flow continuously, by modulating the pressure drop at the level

  of the valve, this modulation being determined by the modula-

  tion of the spacing between the valve 18 and the seat 17, this spacing being itself modulated by the modulation of the average electric current applied to the coil 21. In addition, as the section of the valve 18 can be small, the solenoid can be small, low power and low power consumption, therefore inexpensive, in a valve

simple and economical structure.

  This electric current is supplied for example by a control computer of a carburetor or a computer of an engine control system, integrated into the control unit 10, and this current can be produced from information coming, in particular , a richness probe 24, of the lambda probe type detecting the oxygen content in the exhaust gases of the engine passing through the exhaust manifold 25, as well as of the pressure sensor 23, as

explained above.

Claims (10)

  1. Electrically controlled valve with continuous opening in operation, for the regeneration of a canister (1) associated with an internal combustion engine (M) supplied with air or carburetted air by at least one intake duct (5) wherein the flow is controlled by a movable throttle member (6), the canister (1) in which fuel vapors are collected being, on the one hand, provided with a vent (4) in communication with the atmosphere and, on the other hand, connected to the intake duct (5) downstream of the throttle member (6) by a pipe (8) on which is mounted said valve (9), which comprises a calibrator ( 16) with a constant passage section and a housing (11) delimiting a chamber (12) placed in communication by an inlet (13) with the canister (1) and by an outlet (14) with the intake duct (5) , and in which a valve (18) for controlling the purge flow rate of the canister (1) is mounted movable relative to a seat (17) closable by the valve   (18), which is linked in movement to a core (20) of a sol-   noid whose coil (21) is supplied by a variable average electric current (I) to control the force on the valve (18) and its spacing from the seat (17) in the valve open position (9), characterized in that the outlet (14) from the chamber (12) is connected to the intake duct (5) via the calibrator (16) so that the pressure downstream of the calibrator (16) is the pressure in the conduit (5) downstream of the throttle member (6), while the inlet (13) of the chamber   (12) is directly connected to the canister (1) by the pipe-   tion (8), so that the upstream of the seat (17) is at atmospheric pressure or at a pressure close to the latter, and the purge flow passing through the calibrator (16) is continuously modulated by modulating the difference   pressure at the valve (18) resulting from the modula-   tion of the force applied to the valve (18) by the modulation   variable mean current (I) in the coil (21).   2. Valve according to claim 1, characterized in that it further comprises elastic means (22) for biasing the valve (18) towards its closed position against the seat (17), and in that the supply electric coil (21) of the solenoid develops a magnetic force (Fm) biasing the valve (18) against the elastic means (22) in the open position of the seat (17). 3. Valve according to claim 1, characterized in that when the engine is stopped (M), the coil (21) of the solenoid is supplied by an electric current such that the valve (18) is subjected to a magnetic force l applying against   its seat (17) in the closed position of the valve (9).   4. Valve according to any one of the claims   1 to 3, characterized in that the variable mean current (I) is obtained by supplying the solenoid coil (21) with rectangular electrical current slots with ratio variable cyclic.   5. Valve according to any one of the claims   1 to 4, characterized in that the variable mean current (I) is controlled by a control member (10) sensitive to at least one signal from at least one sensor of an engine operating parameter (M), such as a richness sensor (24) of the air-fuel mixture, and / or a pressure sensor (23) in the intake duct (5) in   downstream of the throttle member (6).   6. Valve according to any one of the claims   1 to 5, characterized in that the seat (17) is arranged   around the entrance (13) of the room (12).   7. Valve according to any one of the claims   1 to 6, characterized in that the valve (18) is directly secured in movement to the core (20) which is housed with the coil (21) of the solenoid in the chamber (12) of the valve (9).   8. Valve according to claim 7, characterized in that the chamber (12) is delimited in a housing (11) of substantially cylindrical shape, and the valve (18), the seat (17), the inlet (13) of the chamber (12), the core (20) and the coil (21) of the solenoid and, optionally, the outlet (14) of the chamber (12), are substantially coaxial with the axis longitudinal of the housing (11).   9. Valve according to any one of the claims   7 and 8, characterized in that the valve (18) is in one piece with the core (20) by a rod (19) at least partially engaged axially with the core (20) in the solenoid coil (21).   10. Valve according to claim 9, as attached to claim 3, characterized in that the elastic return means comprise at least one helical spring (22) housed in the chamber (12) between the valve (18) and a support of the coil (21) in the chamber (12) of the valve (9).