Internal combustion engine of the fuel injection type having means for reducing the emission of unburned products with the exhaust gases

Abstract

For an internal combustion engine of the fuel injection type, improved means are disclosed, aiming at reducing the emission of an unburned fraction in the exhaust gases, so as to diminish the causes of pollution of the atmosphere. According to the improvement, fuel feed cut-off means and air feed cut-off means are provided to cut off both the fuel feed and the air feed when the conventional fuel feed regulating means and air throttling means are in "idling" position and the engine speed is higher than the idling speed.

Parent Case Text

RELATED APPLICATION

This is a continuation in part application of my earlier application Ser. No. 191,453, now abandoned, filed Oct. 21, 1971.

Description

BACKGROUND OF THE INVENTION

One of the most significant factors contributing towards air pollution and, more particularly in inhabited areas, is the emission, by internal combustion engines of motor vehicles, of exhaust gases which contain a not negligible fraction of unburned products.

It has been shown that a significant fraction of the unburned products is emitted by an engine when the latter is driven to rotation by the transmission unit, thus giving a negative torque: this phenomenon occurs, in actual practice, whenever the driver releases the accelerator pedal, thus closing the throttle and the engine, as connected to the vehicle wheels, is driven to rotation at a rate which exceeds the one attendant to it as a function of the air gasoline mixture drawn into the engine; the resultant braking action is resorted to for decelerating the vehicle run, or to prevent it from accelerating, as it occurs when the vehicle is descending a slope.

It is known that in an engine which is driven at a comparatively high speed when the accelerator pedal is released, carburation difficulties are experienced, due to the high negative pressure obtaining downstream of the throttle and of the small rates of flow of both air and gasoline concerned: in addition, combustion difficulties are also originated inasmuch as the comparative rarefaction of the mixture encourages the phenomenon of extinction of the flame in the neighborhood of the combustion chamber walls. These phenomena, along with others, are responsible for a considerable percentage of unburned fractions in the exhaust gases.

In order to limit the emission of unburned fractions, in internal combustion engines of the fuel injection type, it has been suggested to adopt devices which cut off the fuel injection to the engine when the latter is driven by the vehicle wheels: this approach has the defect that the gases coming from the oil sump, which is connected to the air suction duct, do not burn and thus soil the interior of the cylinders and are discharged into the atmosphere: a further, but not less serious drawback is that the air drawn into and exhausted from the cylinder, if no combustion takes place, cools the cylinder walls, with the result being difficulties in the combustion and an increase of the emission of unburned fractions whenever the released accelerator pedal is depressed again.

OBJECTS AND SUMMARY OF THE INVENTION

An object of the present invention is to reduce the emission of unburned fractions in the exhaust gases of an internal combustion engine of the fuel injection type which is driven to rotation at a rather high rate and with the throttle placed in the idling position.

An additional object of this invention is to render particularly high the braking torque supplied by the engine when the accelerator pedal is released.

According to the invention, an internal combustion engine of the fuel injection type is provided, which comprises a combustion chamber, an intake duct leading to said chamber, fuel injecting means located in said intake duct, fuel feed means connected to said fuel injecting means, regulating means coupled to said fuel feed means to regulate the fuel feed, air feed means introducing air in the intake duct upstream to the fuel injecting means, throttling means coupled to said air feed means to regulate the air feed concurrently with the operation of said regulating means, fuel feed cut-off means, air feed cut-off means and control means responsive to the concurrent operation of said regulating means and said throttling means and to the engine speed to actuate the fuel feed and air feed cut-off means to cut-off the fuel feed and the air feed when said regulating means and said throttling means are arranged to regulate the fuel feed and the air feed at the idling values and the engine speed is higher than the idling speed.

Otherwise stated, according to the present invention both the fuel feed and the air feed are cut off when the engine is driven by the vehicle wheels, so that the above mentioned drawbacks encountered in the fuel injection engines which are only provided with fuel feed cut-off means are thus eliminated and a relevant reduction of unburned fractions in the exhaust gases is obtained.

In order that the present invention may be better understood, two exemplary embodiments thereof will now be described and diagrammatically shown in the accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatical view, partly in section, of an exemplary embodiment of the invention, and

FIG. 2 is a view, similar to FIG. 1, of an alternative exemplary embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

As appears in FIG. 1, an internal combustion engine of the fuel injection type has a combustion chamber 14, an exhaust duct 15 and an intake duct 13, which communicates with a manifold 12, where other intake ducts of every cylinder may open, according to a well known diagram. An air intake pipe, generally shown at 1, is flanged onto the manifold and to an air filter 51 communicating with the atmosphere. A main internal duct 26 of the pipe 1 is throttled by a throttle 2, whose arbor 3 is rotatably and controllably supported by the pipe walls and is operatively connected to the accelerator pedal (not shown) of the vehicle. An auxiliary idling duct 4 by-passes the throttle 2 and opens downstream of the throttle in registry with a calibrated bore 5. The duct 4 is equipped with an intercepting member consisting of an obturator or valve member 7 which, by an axial movement, can have its portion 6 resting against a corresponding seat 9, thus closing the duct. The obturator 7 is driven by a solenoid 8 which, as it is energized, drives the valve member to contact the seat 9, against the bias of resilient means, not shown, which bring it back to the at rest position shown in the drawing, when the solenoid is not energized. The solenoid has a terminal 11 connected to ground and a terminal 10 connected, through a line 31, to a pole of a current generator 29, whose other pole is connected to ground: on the line 31 there are, serially connected, two switches 32 and 33, respectively. The switch 32 is mechanically ganged with the throttle 2 in the sense that it is closed when the throttle closes the duct 26; the switch 33 is controlled by a device 28, which is conventional per se and, which receives, through a line 30, a signal which is a function of the rotational speed of the engine; as said speed exceeds a predetermined threshold value, above the idling value, the device causes the switch 33 to be closed; when the speed is below said threshold value, the switch is driven to opening.

As shown in FIG. 1, a fuel injecting means 43 is located within the intake duct 13 and has a fuel feed means 44 connected thereto. A regulating means 45 is coupled to the fuel feed means 44 to regulate the fuel feed between minimum and maximum values depending on the position of the accelerator pedal of the vehicle and on the running speed of the engine. More precisely, the regulating means 45 is connected to the throttle 2 so as to regulate the fuel feed at the minimum or idling value when the throttle is closed. A fuel feed cut-off means 41 is also coupled to the fuel feed means 44 to cut off the fuel feed when electrically energized. An electrical lead 42 connects the fuel feed cut-off means 41 to the energizing line 31.

In operation, when the accelerator pedal is released, i.e. the throttle 2 is closed and the regulating means regulates the fuel feed at the minimum of idling value, and the engine rotates at the idling speed, the switch 32 is closed but the switch 33 is open, so that the solenoid 8 is de-energized and the auxiliary duct 4 is open and keeps the air feed at a minimum or idling value; the fuel feed cut-off means 41 also is de-energized. In such a case, if the engine is accelerated, the switch 33 is closed, but the line 31 is nevertheless cut off by the opening of the switch 32 and the solenoid 8 is still de-energized.

Conversely, when the accelerator pedal is released but the engine rotates at a speed higher than the idling speed, the switches 32, 33 are simultaneously closed, so that the solenoid 8 is energized and the 7 closes the duct 4, thus cutting off the air feed. The fuel feed cut-off means 41 also are energized and entirely cut off the fuel feed, so that neither fuel nor air are introduced into the combustion chamber 14 and the exhaust duct 15 discharges only negligible amounts of gases, such as may seep through an imperfect tightness of the throttle 2 and valve member 7. It is to be noted that the switches 32 and 33 of the embodiment shown in FIG. 1 could be actuated by the same actuating means used in the regulating means 45 to regulate the fuel feed as a function of the position of the accelerator pedal and the engine speed.

An additional exemplary embodiment of the invention is shown in FIG. 2 and parts thereof which correspond to those of the embodiment of FIG. 1 have been indicated by similar reference numerals and will not be explained in detail.

In this second embodiment, the bore 5 can be placed alternatingly in communication either with the duct 4 or a duct 17, according to whether a valve member 21 rests against a seat 20 or, against a seat 16, respectively.

The duct 17 is connected by a duct 19 to the exhaust duct 15 through a filter 27, for example of the cyclone type, and in any case, a filter capable of separating both solid and liquid particles from the gas flowing therethrough.

The valve member 21 is controlled, with the intermediary of a stem 22, by a solenoid 23 which, as it is energized, brings the valve member back to the seat 16 against the bias of resilient means (not shown) which urges the valve member to contact the seat 20 when the solenoid 23 is not fed. A terminal 24 of the solenoid is connected to ground and a terminal 25 is connected, through a line 38, to a pole of the current generator 29, whose other pole is also connected to ground. On the line 38 there are, serially connected, two switches 39 and 40: the switch 40 is connected to the throttle 2 in the sense of being closed as the throttle is closed, while the switch 39 is connected to a diaphragm 35 which can be deformed against the bias of a compression spring 34 and which closes the chamber 36 which communicates, through a duct 37, with the manifold 12. The fuel feed cut-off means 41 also is connected to the energizing line 38 via the line 42.

In operation, when the accelerator pedal is released (or, anyhow, the throttle 2 is closed and the regulating means 45 keeps the fuel feed at the minimum or idling value) and the engine is driven at the idling speed, the switch 40 is closed but the negative pressure in the manifold 12 is not sufficient to overcome the bias of the spring 34 on the diaphragm 35, so that the switch 39 remains open and the solenoid 23 is not energized. The valve member 21 thus remains in the position of FIG. 2, so that the recycling duct 19, 27, 17 is closed and the minimum or idling duct 4, 5 is open. The fuel feed cut-off means 41 also is de-energized.

As the engine is accelerated by depressing the acccelerator pedal, the switch 40 is opened and the operation of the assembly is conventional.

When, conversely, the accelerator pedal is released but the engine is driven at a comparatively high speed of rotation, the negative pressure in the manifold 12 is increased until overcoming the bias of the spring 34, so that the switch 39 is closed and the fuel feed cut-off means 41 and the solenoid 23 are energized to cut off the fuel feed and to move the valve member 21 towards the seat 16 to cut off the idling duct 4,5.

This movement of the valve member 21 causes also the recycling duct 19, 27, 17 to be opened, so that the exhaust gases are recirculated from the exhaust duct 15 to the intake duct 13 and prevent the negative pressure in the intake duct from attaining too high a value, such as to give rise to excessive seepings through the throttle 2 and valve member 21. The recycling duct thus attains the result to improve the cut-off action of the fuel feed and air feed cut-off means 41 and 21. Of course, the bore 5 should have an adequate size so as to prevent an excessive flow of recycled gas, which could lower the magnitude of the negative pressure in the manifold 12 to a value not sufficient to maintain the switch 39 closed. It is also important to notice that the recycling of hot exhaust gases allows a flow of gas in the engine, when no combustion occurs, without experiencing too intensive a cooling of the combustion chamber, whose consequence would be the emission of unburned fractions as the engine resumes its normal operation.

The embodiments shown in the drawings are, as outlined above, mere examples and many modifications can be provided for without thereby departing from the scope of the present invention. More particularly, the control circuits for the solenoid as illustrated can be indifferently applied to either embodiment described herein.

Claims

What is claimed is:

1. An internal combustion engine of the fuel injection type, comprising a combustion chamber, an intake duct leading to said chamber, fuel injecting means located in said intake duct, fuel feed means connected to said fuel injecting means, regulating means coupled to said fuel feed means to regulate the fuel feed, air feed means for introducing air in the intake duct upstream to the fuel injecting means, throttling means coupled to said air feed means to regulate the air feed concurrently with the operation of said regulating means, fuel feed cut-off means, air feed cut-off means and control means responsive to the concurrent operation of said regulating means and said throttling means and to the engine speed to actuate the fuel feed and air feed cut-off means to cut off the fuel feed and the air feed when said regulating means and said throttling means are arranged to regulate the fuel feed and the air feed at the idling values and the engine speed is higher than the idling speed, the air feed means comprising a main duct in which said throttling means is arranged and an auxiliary duct in parallel therewith, said air feed cut-off means being defined by a valve member which is actuated to close said auxiliary duct when the throttling means closes said main duct and the engine speed is higher than the idling speed, and wherein the combustion chamber is provided with an exhaust duct which is connected to the intake duct via a recycling duct provided with gas recycling cut-off means which normally closes said recycling duct and which is controlled to open said recycling duct when said air feed cut-off means is actuated.

2. The internal combustion engine as claimed in claim 1, in which said valve member is controlled by an electromagnet so as to be moved to the closing position when the electromagnet is energized.

3. The internal combustion engine as claimed in claim 2, in which said electromagnet is fed by a current generator through a line on which there are, serially arranged, a first switch and a second switch, the first switch being connected to the throttling means so as to be closed when the throttling means close said main duct, and the second switch being controlled by a device sensitive to the engine speed so as to be closed when said speed exceeds the idling value.