FR2516984A1 - ELECTRONICALLY CONTROLLED EXTERNAL INJECTION FUEL APPARATUS FOR INTERNAL COMBUSTION ENGINES - Google Patents

Abstract

THIS APPLIANCE FOR COMMANDING THE INTRODUCTION OF FUEL AND AIR IN AN INTERNAL COMBUSTION ENGINE IS OF THE TYPE HAVING A FUEL INJECTOR 5 DOWNSTREAM OF AN AIR THROTTLE 7, 11. THE INJECTOR 5 IS CONTROLLED BY AN ELECTRONIC SYSTEM INCLUDING SEVERAL SENSORS, SUCH AS AN INLET AIR FLOW SENSOR 29 AND A HIGH NEUTRAL SENSOR. TO SIMPLIFY THE PART OF THE CONTROL SYSTEM RELATING TO THE DETECTION OF THE INTAKE AIR FLOW, THE THROTTLE BODY CONSISTS OF A VARIABLE FLOW SONIC TYPE VALVE, INCLUDING A VENTURI TYPE 8 TUBE AND A CORE TRUNCONIC SHUTTER 11 WHICH IS AXIALLY MOBILE IN THE TUBE 8 AND IS OPERABLE BY THE ACCELERATOR PEDAL (CABLE 24) OF THE MOTOR. WITH SUCH A VALVE, THE AIR FLOW SENSOR MAY BE CONSTITUTED BY A SINGLE RESISTANCE POSITION SENSOR 29 ATTACHED TO CORE 11 OF THE VALVE.

Description

16984

  The present invention relates to an apparatus for controlling the introduction of fuel and air into an intake manifold

an internal combustion engine.

  One of the main problems facing the modern automobile industry is to optimize the relationships between fuel consumption, power supplied, emissions

  exhaust and manufacturing costs of combustion engines-

internal tion.

  Two types of carburetion apparatus are known and currently used on a large scale: the carburetor type and

  the type with external or indirect injection.

  Devices of the latter type have an organ

  throttle to adjust the air flow in the intake manifold

  at least one electronically controlled fuel injector installed downstream of the air throttle and a device

  electronic control unit to control the injector or injectors

  fuel teurs according to different quantities linked to the engine operating conditions, such as the intake air flow and the instantaneous rotation angle (of the crankshaft) of the engine> generally indicated by the arrival at the positions of top dead center, the control device comprising sensors for detecting the various quantities, among which may also include, for example, the speed of rotation of the motor and

  the engine coolant temperature.

  The device of the type with external injection has certain advantages with regard to fuel consumption, the power supplied and the exhaust emissions but it is more expensive to manufacture With regard to this last point, one of the components of the device playing an important role in the costs

  of manufacture is the air flow sensor with the corresponding part

  weight of the control device Such a sensor is however essential for the proper control of the air throttle (typically formed by a butterfly) if an optimal air / fuel ratio must be maintained in order to improve efficiency of

engine.

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  The invention aims to provide an improved carburetion device of the external injection type which, while retaining the safety characteristics, low fuel consumption and power supplied specific to this type of device, ie a cost price low and can be installed and maintained quickly

and simply.

  According to the invention, such an apparatus is essentially characterized in that the air throttling member is a valve of the sonic type with variable flow constituted by a nozzle of the kind

  Venturi with predetermined profile and by a truncated shutter core

  nique, also having a predetermined profile, which is arranged coaxially in the nozzle and is axially movable relative

  to the latter by the operation of the accelerating control member

  engine, the sensor for the intake air flow being a position sensor sensitive to the position of the core in the nozzle. Other characteristics and advantages of the invention

  will emerge more clearly from the following description of a

  nonlimiting exemplary embodiment, as well as the accompanying drawings, in which: FIG. 1 is an overall view of a carburetion apparatus according to the invention, partly in axial section and partly schematic; Figure 2 is an axial section on a larger scale of the nozzle body of the air intake valve visible in Figure 1; and Figure 3 is an axial section on a larger scale

of the obturator core of this valve.

  In the accompanying drawings, 1 denotes the cylinder head of an internal combustion engine. In this example, it is a four-cylinder in-line engine, but the carburetion apparatus according to

  the invention is also applicable to engines having a different number

  rent of cylinders, which can also be arranged in V or be opposite

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  Of course, in the latter two cases, it would be necessary to provide a separate carburation device for each row.

of cylinders.

  The cylinder head 1 of the example shown has interior

  Rely the intake ducts for the different cylinders, opening through a single intake manifold 2 When such an arrangement is not provided in the cylinder head itself, it can

  of course be carried out by external piping.

  On the intake manifold 2 is fixed a connection elbow.

  dement 3, having in its upper part a housing 4 for

  a fuel injector 5 of known type and shown diagrammatically

  only. At the other end of the elbow 3 is fixed, by bolts 6, an air throttling valve 38 of the sonic type and with variable flow rate. This valve has a cylindrical body 7 forming an axial nozzle 8 having the shape of a Venturi nozzle and whose dimensions are calculated to give optimal efficiency to the

  current of air having the flow rate provided for supplying the motor.

  The dimensions indicated below for the nozzle 8 apply to a specific embodiment; it goes without saying that the diameter of the nozzle must be changed only as a function of the maximum air flow rate that one wishes to obtain, depending on the type

of the engine in question.

  From the point of attachment to the elbow 3, the nozzle 8, see also FIG. 2, has a section of 12 ma of axial length with an angle of 97 7.5 'with the perpendicular to the axis of the nozzle 8, then a section of 10.5 mm at 95 26.47 '; a section of 12.5 m at 920 17.44 '; a section from 12.5 mm to 90; a section from 12.5 to 87 42.56 '; a section of 5 mm at 78 41.41 '; a

  section from 17 mm to 750 36.63 '; and a section of 3 min at 28 36.63 '.

  The total length of the nozzle 8 is therefore 85 mm.

  The diameter of the outer edge of the last section of axial length 3 mm has been calculated at 50 mm for an engine with a displacement of 903 cm

  and a maximum rotational speed of 5,600 rpm.

  In the first section opens a bore 9 which a pipe 10 connects to a pressure regulator controlled by the system

  of the fuel injector.

  A frustoconical core II forming a shutter is arranged coaxially in the nozzle 8, with its end of small diameter

  towards the connection elbow 3.

  The dimensions of the core 11 are also calculated with a view to obtaining optimal efficiency in combination with the

  Venturi nozzle profile 8 The shape and size

  ment of the core l I of the example shown, see in particular FIG. 3, are as follows The end of small diameter is formed by a cylindrical portion 15 mm long. To this extreme portion is connected a conical portion of a axial length of 90 mm, with a large diameter of 30 mm at the other end, including the generator

  contains an angle of 50 42.6 'with the axis of the core.

  Of course, these dimensions have also been calculated for a four-cylinder engine of the type indicated It goes without saying that, if the diameter of the nozzle 8 is changed, it will also be necessary to change the diameter of the core 11, so as to maintain at least

  roughly the proportions indicated.

  The core It has an axial hole 12 which extends over a considerable part of its length and by which it is slidably mounted on a spindle 13 This is mounted on the axis of the nozzle 8 and has a diameter substantially equal to the diameter of

hole 12 -

  The spindle 13 is screwed into a tapped hole 14 at the bottom of a cylindrical cap 15 fixed coaxially to the cylindrical body 7

  by a pin 16 and bolts 17.

  The core It can be moved on the spindle 13 by means of a rod 18 fixed at one end to a hollow cylindrical connecting piece 19 sliding on the spindle 13 and screwed into the large diameter end of the core The other end of the rod 18 protrudes outside through a hole in the cap 15 and is articulated to an arm 21 mounted itself oscillating on the cap 15 by an axis

  23 carried by the hat and passing through a slot 22 in the arm.

  The outer end of the arm 21 is attached to the accelerator cable 24 of the engine. Thus, when the driver presses the accelerator pedal, it produces a corresponding displacement.

  the obturator core 11 in the nozzle 8.

  To the connecting piece 19 is rigidly fixed a second rod 25, the other end of which projects outside through a hole 26 in the cap 15 and is rigidly attached to an arm 27 fixed

  to the actuating rod 28 of a resistance position sensor 29.

  This sensor provides a signal representative of the position of the core 11, therefore also of the air flow at the intake. The variation of the length.

  of the rod 25 makes it possible to adjust the position of the corresponding sensor 29

when setting the minimum.

  A pipe 31 in which a filter 32 is incorporated and which is used for the intake of air to the atmosphere is clamped on the cap.

15 around a light 30.

  The fuel injector 5 is controlled by an electronic system which comprises a certain number of sensors providing indications representative of the operating state of the engine and comprising in this example a temperature sensor 33, a top dead center sensor 37 intended to provide an indication of the instantaneous angle of rotation of the motor, a tone wheel sensor 42 intended to provide an indication of the speed of the motor, as well

  that the air flow sensor 29 combined with the air valve 38.

  The sensors are connected to a control unit

  electronic 40, of conventional type, which controls the function-

  operation of the injector in a known manner depending on the signals

delivered by the sensors.

  The injector 5 is also connected to the fuel system.

  fuel statement, comprising a fuel tank 53,

  a fuel filter 54 and a pump 55 arranged in series.

  Downstream of the pump 55 is a pressure regulator 56 which is connected to the tank for the return of excess fuel to it. The pressure regulator 56 is controlled by a signal coming through the electronic control unit 40 , from the position sensor 29 of the air throttle valve 38 to

variable flow.

  The main feature 6 of the air valve 38 is that it is a sonic type throttle valve, which means that at each section of the circular passage defined between the outer profile of the core 11 and the profile inside the body 7 corresponds to a determined air flow, at least within the normal operating range of the engine. This means that, in the device shown, the air flow can be determined at any time by a simple sensor. resistance position 29 coupled to the valve core 11 and permanently indicating the position of

this one.

Claims (4)

R E V E N D I C A T I O N S   1 Apparatus for controlling the introduction of fuel and air into an intake manifold of an internal combustion engine, in particular of an engine operating according to the Beau de Rochas cycle, apparatus which has a throttling member d air to regulate the air flow in the intake manifold, at least one electronically controlled fuel injector installed downstream of the air throttle and a control device   electronic to control the fuel injector (s)   according to different operating variables of the   engine, including intake air flow and rotation angle   instantaneous motor control, the electronic control device comprising sensors for detecting the different quantities, characterized in that the air throttle member is a valve (38) of the sonic type with variable flow rate constituted by a nozzle (8 ) of the Venturi type with a predetermined profile and by a frustoconical obturator core (11), also having a predetermined profile, which is arranged coaxially in the nozzle (8) and is axially displaceable relative to the latter by the operation of the member engine accelerator control, the sensor for the intake air flow being a sensitive position sensor (29)   at the position of the core (11) in the nozzle (8).   2 Apparatus according to claim 1, characterized in that the nozzle (8) of the Venturi type has a total length of 85 mm and has a first section of 12 mm in axial length with an angle of 97 7.5 'with the perpendicular to the axis of the nozzle (8), followed by a section of 10.5 mm at 95 26.47 '; a section of 12.5 mm at 92 17.44 '; a section from 12 e 5 mm to 90; a section of 12.5 mm at 87 42.56 '; a section of 5 mm at 78 41.41 '; a section   from 17 my to 73 36.631; and a section of 3 mm at 28 36.63 '.   3 Apparatus according to claim 2, characterized in that the frustoconical obturator core (11) has a total length of 105 mm, of which 15 mm are cylindrical and 90 e are conical, the generatrix of the conical portion making an angle of   5 42.6 'with the axis of the core (11).   I 4 Apparatus according to claim 3, characterized in that the diameter of the outer edge of the last 3 mm long section of the nozzle (8) is 50 mm and the diameter of the large end of the   conical portion of the core (11) is 30 mm.