FR2699603A1 - Electrically controlled canister regeneration circuit valve. - Google Patents

Abstract

The valve has its valve (19) linked in movement to the plunger (20) of a valve opening solenoid (21), and to the diaphragm (12) pushed by a return spring (22) towards the closure of the valve on the outlet (18), connected to the engine intake duct. The chamber (14) of the valve (19) is connected to the canister through the fixed sizer (17). The chamber (13) on the other side of the membrane (12) is at atmospheric pressure or canister pressure. The vacuum which acts on the calibrator (17) is applied to the membrane (12) also subjected to the forces of the spring (22) and of the solenoid (20-21). The canister regeneration rate is thus modulated continuously through the calibrator (17) by a variable depression controlled by the modulation of the average control current of the solenoid. Application of the proportional valve with continuous flow for the regeneration of internal combustion engine canisters.

Description

i

  "ELECTRICALLY CONTROLLED CIRCUIT CONTROL VALVE

REGENERATION OF CANISTER "

  The invention relates to a canister regeneration circuit electrical control valve for an internal combustion engine fed with air or with air fueled by at least one intake duct in which the flow rate is

  controlled by a shutter, for example of the rotary type.

  More specifically, the invention relates to a proportional valve with a continuous flow rate, slaved to an electric command signal, for a regeneration circuit of the canister associated with an internal combustion engine, whose fuel supply system can either include a carburetor, whose rotary shutter, or throttle valve, controls the flow of carbureted air or fuel-air mixture, or be of the type called "injection" and comprise a throttle body, including the rotary shutter

  controls the intake air flow.

  In order for motor vehicles to comply with current anti-pollution standards for fuel or fuel vapor emissions,

  internal combustion of which they are equipped either

  or stopped, it is known to collect in a receptacle called canister fuel vapors from various organs containing or traveled by fuel, in the circuit followed by the latter in the vehicle and its engine On vehicles equipped with an injection fuel supply plant, fuel vapors come in particular from the fuel tank But generally, fuel vapors, can also come from the engine, injection pipes and injectors, or , the

where appropriate, the carburetor.

  To avoid their rejection in the ambient air, these fuel vapors are collected by a recovery line, which leads them to the canister, made in the form of a receptacle containing means for absorbing these fuel vapors, for example a charge of activated charcoal, fulfilling the role of a sponge and a filter vis-à-vis the fuel vapor that reaches the canister The latter is provided with a vent in communication with the atmosphere, so that the fuel tank

  is vented through the canister.

  To prevent the canister from rejecting fuel

  in the open air by its vent, when it is saturated with

  it is known to regenerate it cyclically. For this purpose, it is known to use a regeneration circuit of the

  canister, which purges from time to time the latter of the

  it has absorbed, and transmits this fuel to the engine.

  The canister regeneration circuit includes a channel

  connecting the canister to the intake duct, downstream of the rotary shutter, and a valve mounted on this duct When the valve is open, the negative pressure prevailing downstream of the rotary shutter in the intake duct ducting and in the canister a suction of ambient air by the canister vent, and this ambient air sucked thus purges the canister of the fuel that it contains and mixes with this fuel to be sucked with it downstream of the shutter rotating in the intake duct We understand that the arrival of

  this carbureted air modifies the richness of the air-

  fuel prepared by appropriate engine components (carburetor or injector as appropriate) receiving orders

  using signals from different

  motor operating parameters, and in particular a so-called X probe, or probe measuring the

  of oxygen in the exhaust gas.

  In order to eliminate this disturbance of wealth,

  it has already been proposed that the valve of the regeneration circuit

  an electrically controlled valve for modulating the regeneration flow of the canister, which

  flow is difficult to know because the fuel

  ble collected in the canisters can not be known precisely and depends on many parameters, such as ambient temperature, resulting or not from the operation of the engine, the temperature and the conditions of filling of the fuel tank, etc. For this purpose, the electrically operated valves

  usually used are valves comprising a cali-

  a constant flow cross section, and a flow control valve in the regeneration pipe, the valve being connected in motion to a solenoid core, the coil of which is supplied with an electric current of

control of the position of the valve.

  In these valves of traditional type, the variation of the flow is obtained by modulating the effective section of the calibration subjected to the depression of the motor, this modulation

  being provided by the valve which is that of an electromagnetic

  no, that is to say an electromagnetic valve operating in all-but, whose solenoid coil is fed with electric power with rectangular slots with cyclic ratio of variable opening that is to say that the time of d opening, for a constant period, corresponds to a variable fraction of that period, corresponding to the

  length of the current niche used.

  For an engine running at 3000 rpm, for example, a

half turn is covered in 10 ms.

  In the embodiments of the state of the art, low-frequency solenoid valves excited at constant frequencies ranging from 5 to 20 Hz have been used. They correspond to these frequencies of constant periods ranging from 200 to 50 ms. If the opening duty cycle is 10%, this results in a corresponding rectangular length of the current slot, and therefore substantially a duration of opening of the valve from 20 to 5 ms It follows that the opening time of the solenoid valve, and therefore the suction time of the canister regeneration fuel in the intake duct, ranges from about a quarter to about three

  The consequence is that this fuel

  tible regeneration can not be allowed in all

engine cylinders.

  The use of low frequency solenoid valves for the regeneration of canisters therefore has the drawback

  cause an imbalance in the feeding of the cylinders

engine.

  To overcome this drawback, it has been envisaged to use high frequency solenoid valves, but their rapid wear related to their high frequency of operation,

  and their high cost made them stand aside.

  By the invention, it is proposed to overcome these disadvantages, and an object of the invention is to provide an electrically controlled valve for spreading the regeneration flow so that all the engine cylinders receive substantially the same fraction fuel

regeneration of the canister.

  Another object of the invention is to propose an electrically controlled valve making it possible to provide a regeneration flow rate of the canister which is continuous, but modulated and slaved to an electrical reference signal, so as to

  obtain a proportional flow valve at this setpoint.

  The idea behind the invention is to modulate the regeneration rate of the canister by passing this flow through a calibrator constant passage section, but which is subjected to a modulated depression, unlike the solenoid valves of the canister. state of the art, in which the cross-section of the calibration is modulated

subjected to engine depression.

  For this purpose, the electric control valve according to the invention, for a canister regeneration circuit of the type presented above, comprising a pipe connecting the canister to the intake duct, downstream of the shutter, and on which is mounted the valve which comprises a calibrator of constant flow section, a flow control valve in the pipe and which is linked in motion to a core of a solenoid whose coil is powered by an electric current to control the effort on the valve, is characterized in that the valve is integral in motion with a flexible membrane, which delimits in a housing two chambers, a first is maintained at a pressure close to or equal to atmospheric pressure, and the second is a modulated vacuum chamber, enclosing the valve and placed in communication, through an inlet port, with the canister via said calibrator, and through an outlet port with a the inlet duct, the membrane thus subjected to a depression close to or equal to that acting on the calibrator being also subjected to the opposing forces of elastic means, which tend to close the valve on the outlet orifice, and the solenoid , whose coil creates a force having the effect of moving the valve out of the outlet orifice to open the latter, when it is traversed by a variable average current constituting a signal of

  electrical setpoint fixing the force on the valve.

  It is understood that in operation, the membrane is in equilibrium under the combined actions of the depression, which determines the flow rate, elastic means, which tend to return the valve in the closed position, and the force

  due to the solenoid, and therefore the current flowing through its coil.

  We thus establish a relationship between depression, and therefore

  flow, on the one hand, and, on the other hand, the electric current

  that means that travels the solenoid coil This valve allows to modulate the regeneration flow continuously via a variable vacuum

  determined using an average control current.

  Advantageously, the variable average control current is obtained by supplying the solenoid coil with square-wave rectangular electric current slots.

cyclical variable.

  For a motor powered by a carburettor controlled by a computer, or powered by an injection system controlled by an engine control system, the average variable control current will be advantageously controlled by a control member responsive 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, this control member being the carburettor control computer or the engine control unit.

engine control system.

  The valve can be linked in motion to the solenoid core by means of reducing the amplitude of the displacement of the valve relative to the amplitude of the displacement of the core, in order to best adapt each of these displacements to the practical needs. to reduce the cost of realization of the valve and its size, it is advantageous that, in a simplified structure, the valve is directly integral in movement of the solenoid core, the valve and the core being arranged on the side and

other of the membrane.

  In a preferred embodiment, the valve is in one piece with the core, which extends partially

  in the first chamber, and the elastic means comprise

  at least one return spring, housed in this first chamber, and made in the form of a helical spring partially surrounding, and preferably substantially coaxially the core. Thus, a better guiding of the valve-core assembly in its displacements is obtained. along its longitudinal axis, which is also that of the helical spring and advantageously of the coil of the solenoid,

  as well as more balanced solicitations from the membra-

born.

  The first chamber can be maintained at atmospheric pressure or canister pressure,

  which is little different from the atmospheric pressure.

  In this second case, the first chamber is in communication with the canister via an inlet port and has an outlet port in communication with the inlet port

  of the second chamber via the calibrator.

  A continuous flow valve is thus obtained and modulated by modulating the average control current flowing through the coil of the solenoid, the valve being compact and easy to mount, since it is sufficient to connect the inlet orifice of its first chamber to the canister and the outlet port of its second chamber to the intake duct, and ensure the power supply of the solenoid by the control current.

  Other advantages and features of the invention

  will be apparent from the description given below,

  By way of non-limiting example, examples of embodiments described with reference to the accompanying drawings, in which: FIG. 1 schematically represents a canister regeneration circuit, comprising the valve according to the invention, and mounted between a canister and an intake duct; carburetor or throttle body of an internal combustion engine, FIG. 2 is a diagrammatic sectional view of a first example of a valve, and FIG. 3 is a view similar to FIG.

a second example of a valve.

  In FIG. 1, the canister 1, with an internal volume generally substantially equal to the displacement of the engine, contains an absorbent or adsorbent filler 2, for example activated carbon, which is charged with fuel vapors, in particular coming from the fuel tank. of fuel, and which are brought to the canister 1 by the recovery line 3 The canister 1 can thus contain for example 100 g of

  It is equipped with a vent 4 connecting it to the atmosphere.

  and is also connected to the intake duct 5 of a carburetor body or throttle body of an internal combustion engine, downstream of the rotary valve or throttle valve 6, whose angular position in the pipe

  5 is controlled to regulate the flow rate of

  air intake, in the case of a throttle body, or carbureted air in the case of a carburetor This connection of the canister 1 to the intake duct 5 is provided by a regeneration circuit 7 of the canister 1, this circuit 7 comprising a regeneration pipe 8 opening, at its inlet, into the canister 1 and, at its outlet, into the inlet duct 5, and a valve 9 with electrical control, connected between the upstream branches 8a 8 and downstream of the pipe 8 The valve 9, two embodiments of which are shown in Figures 2 and 3, is a valve gate whose position is controlled by a solenoid receiving its control electric current of a

  control device schematically represented at 10.

  When the valve 9 is open, the depression prevailing in the intake duct 5 downstream of the throttle valve 6 causes, at the

  through Line 8 and Canister 1, an aspira-

  ambient air through the vent 4, and this air sucked through the load 2 drives the fuel retained by

  the latter in the intake duct.

  In the example of FIG. 2, the valve 9 comprises a body or casing 11 whose interior is subdivided by a flexible and deformable waterproof membrane 12 into two chambers 13 and 14, the first of which 13 is maintained at atmospheric pressure. second chamber 14 has an inlet 15 connected to the upstream portion 8a of the regeneration pipe 8 of the canister 1 by a tubular nozzle 16 enclosing a calibrator 17 or restriction, constant passage section The second chamber 14 also has a outlet orifice 18 connected to the downstream part 8b of the regeneration pipe 8, and the periphery of the outlet orifice 18 constitutes a seat for the conical head of a valve 19 This valve 19, with a cylindrical body,

  is in one piece with the core 20, also cylindrical,

  that of a solenoid comprising an excitation coil 21 mounted on the body 11, outside the first chamber 13, on the opposite side to the outlet orifice 18 The one-piece assembly of the valve 19 and the core 20 is secured to the membrane 12, which it crosses with sealing the central portion The valve 19 is thus supported by the membrane 12 in the second chamber 14, while the core 20, on the other side of the membrane 12, extends partly in the first chamber 13 and partly outside thereof, in the coil 21 The part of the core 20 located in the chamber 13 is surrounded by a helical return spring 22 bearing on the housing 11 and on the membrane 12 to tend to push it in the direction applying the valve 19 to its seat, so as to close the outlet orifice 18 when the coil 21 is not energized.

  housing 11, the membrane 12, the one-piece valve assembly 19-

  core 20, the coil 21 and the outlet orifice 18 are, to ensure better mechanical behavior of the assembly

  19-core valve 20, preferably coaxial with the longitudinal axis

dinal of this set.

  In operation, the coil 21 is traversed by an average control electric current, which results from the supply of rectangular current pulses with a variable duty cycle. The 19-core valve assembly 20 is then subjected to an electromagnetic force Fm which moves the valve 19 of the outlet orifice 18, against the spring 22 The chamber 14 is then in communication with the outlet 18 with the inlet duct 5 and, through the calibrator 17, with the upstream pipe 8 a and the canister 1 The control pressure Pc in the chamber 14 is then intermediate between the pressure of the Pcan canister, upstream

  calibrator 17, itself close to the atmospheric pressure

  Pa in the chamber 13, and the pressure in the intake duct 5, downstream of the throttle valve 6 For a given average control current, and therefore a given position of the membrane 12, the valve 19 and the core 20, understands that if the butterfly 6 is moved in the closing direction, the depression in the intake duct 5 increases downstream of the butterfly 6 The control pressure Pc tends to decrease, and the differential pressure acting on the membrane 12 increases, so that the valve 19 is brought closer to the outlet orifice 18 The passage section decreasing, the control pressure Pc downstream of the calibrator 17 increases, so that the differential pressure exerted on the membrane 12 tends to return to its initial value, and recall the membrane 12, the valve 19 and the core 20 in their initial given position The operation is similar when the butterfly 6 is operated in the opening direction The valve thus functions as a regulator

Auto correction.

  In operation, the membrane 12 is subjected to the return force Fr of the spring 22, which tends to close the valve 19 on the outlet 18, an electromagnetic force Fm exerted on the core 20 by the field created by the coil 21, and to the force resulting from the application, on the effective surface S of the membrane 12, of the differential pressure between the atmospheric pressure Pa in the chamber 13 and the

  control pressure Pc in the chamber 14 In operation

  the membrane 12 is in equilibrium under the action of these three forces, according to the following formula (1) (1) S (Pa Pc) = Fm Fr Simultaneously, the regeneration flow rate Q passing through

  by the calibrator 17 is given by the known formula (2)

  below: 0.5 (2) Q = Sc x 1 2 p (Pc Pc) 1 where Sc is the constant flow section of the calibrator 17, p the density of the air-fuel mixture from canister 1, and Pcan and Pc are respectively the pressure in the canister or upstream of the calibrator 17, and the control pressure in

the room 14.

  Since Pa and Pcan are close to each other, we can, in formula (2), replace Pcan Pc by the value

  of Pa Pc in the formula (1), namely Fm Fr.

  If it is obtained that the flow rate Q is given by the formula (3): (3) Q = Sc x 1 2 p (Fm Fr) 1 0.5 s We note that the regeneration flow rate Q is independent of Pcan, continuous and modulated by the modulation of the electromagnetic force Fm, itself a function of the average control current of the coil 21 The valve is thus a continuous and proportional flow rate, controlled by an electrical current setpoint For this valve to be relatively insensitive to vibrations of the motor, we choose a spring

  22 at low effort threshold but sufficient for this purpose.

  The valve example of Figure 3 does not stand out

  essentially that of Figure 2 than by the different

  following: the housing 11 'has a lateral passage 23, connecting the two chambers 13 and 14 to each other, and in which the calibrator 17 is mounted. The upstream portion 8 a of the regeneration pipe is no longer connected to the chamber 14 through the calibrator 17, but to an inlet 24 of the chamber 13, having an outlet 25 in communication with the inlet 15 of the chamber 14 via the calibrator Thus, the chamber 13 is no longer maintained at atmospheric pressure but directly at the pressure of the Pcan canister. For the remainder, there is the solenoid coil 21 and plunger 20 integral with the valve 19 and integral in motion of the membrane 12 biased in the direction of closing the valve 19 on the outlet orifice 18 of the chamber 14 by the

return spring 22.

  In this example, the differential pressure or depression Pcan Pc acting on the calibrator 17 is applied directly to the membrane 12, also subject to

  spring forces Fr and solenoid Fm, as defined above.

  above The formulas (1) to (3) given above apply

  by replacing Pa by Pcan in formula (1) This valve thus provides the same advantages as that of FIG. 2 and makes it possible to modulate the regeneration flow rate continuously, via a vacuum

  variable, determined by the modulation of an electric current

than control means.

  This electric current is provided for example by a carburettor control computer or a computer of an engine control system, and developed from information derived in particular from a wealth probe, of the probe type y, detecting the oxygen content in the gases

engine exhaust.

Claims (1)

1 electric control valve circuit (7) of canister regeneration (1), for internal combustion engine powered by air or carbureted air by at least one intake duct (5) in which the flow is controlled by a shutter (6), the canister (1) containing means (2) for absorbing fuel vapors fed into the canister by a recovery line (3) and being provided with a vent (4) in communication with the atmosphere, and the regeneration circuit (7) of the canister (1) comprising a pipe (8) connecting the canister (1) to the intake duct (5), downstream of the shutter (6), and the valve ( 9) mounted on the pipe (8), said valve comprising a calibrator (17) with a constant flow section, a valve (19) for controlling the flow in the pipe (8), and which is connected in movement to a core ( 20) of a solenoid whose coil (21) is powered by an electric current to control the force on the valve, characterized in that said valve (19) is integral in motion with a flexible membrane (12), which delimits in a housing (11, 11 ') two chambers (13, 14), one of which ( 13) is maintained at a pressure close to or equal to atmospheric pressure, and the second (14) is a modulated vacuum chamber, enclosing the valve (19) and placed in communication, by an inlet (15) , with the canister (1) via said calibrator (17), and by an outlet (18) with the intake duct (5), the membrane (12) thus subjected to a depression close to or equal to the one acting on the calibrator (17) being also subjected to the opposing forces of elastic means (22), which tend to close the valve (19) on the outlet orifice (18), and the solenoid (20-21) , whose coil (21) creates a force having the effect of moving the valve (19) away from the outlet orifice (18) to open the latter deny, when it is traversed by a variable average current constituting an electrical setpoint signal setting the force on the valve (19). 2 valve according to claim 1, characterized in that the valve (19) is connected in motion to the core (20) of the solenoid by means of reduction of the amplitude of the displacement of the valve relative to the amplitude of displacement of said core . 3 valve according to claim 1, characterized in that said valve (19) is directly integral in motion of said core (20) of the solenoid, the valve and the core being disposed on either side of the membrane (12). 4 valve according to claim 3, characterized in that said valve (19) is in one piece with said core (20), which extends at least partially in said first chamber (13). Valve according to any one of claims 1 to 4, characterized in that said elastic means comprise at least one return spring (22) housed in said first chamber (13). 6 valve according to claim 5, as attached to claim 4, characterized in that said return spring (22) is a helical spring which partially and substantially coaxially surrounds said core (20). Valve according to any one of claims 1 to 6, characterized in that said first chamber (13) is maintained at atmospheric pressure. 8 valve according to any one of claims 1 to 6, characterized in that said first chamber (13) is held at the pressure of the canister (1), with which it is in communication through an inlet port (24), and has an outlet (25) in communication with the inlet (15) of the second chamber (14) via said calibrator (17). 9 valve according to any one of claims 1 to 8, characterized in that said variable average current is obtained by supplying the coil (20) of the solenoid by rectangular electric current slots variable duty cycle. Valve according to any one of the claims   1 to 9, characterized in that said variable average current is controlled by a control member (10) responsive to at least one signal originating from at least one sensor of an operating parameter of the motor, such as a sensor of   richness of the air-fuel mixture.