Fuel Feed Regulating Device

Abstract

An apparatus for regulating the feed of fuel to a mixture-compressing internal combustion engine having a throttle valve and a normally closed sensor flap located within the air intake line. A channel connects the air intake line between the throttle valve and sensor flap to the atmosphere, this channel being opened and closed by a closure flap which is coupled to the sensor flap and a vacuum capsule responsive to the vacuum in the air intake line between the engine and the throttle valve. Regardless of the adjustment of the throttle valve upon the starting of the engine, the apparatus feeds only the necessary amount of fuel to the engine so that errors on the part of the driver during starting do not have an effect on the regulating device permitting the engine to start reliably.

Description

BACKGROUND OF THE INVENTION

The present invention relates to means for regulating the feed of fuel in mixture-compressing internal combustion engines, in which a throttle valve which can be actuated at will is arranged in the air intake line and an idle air bypass is provided between the throttle valve and the internal combustion engine. There is furthermore provided in the air intake line on the side of the throttle valve facing away from the internal combustion engine an eccentrically supported sensor flap. The sensor flap is urged into closed position by a spring and is swingable against the action of the spring in the direction of the flow of the intake air, the sensor flap responding to the difference in pressure in the air intake line in front of and behind the sensor flap and controlling a device for metering the quantity of fuel to be fed to each internal combustion engine chamber in order to obtain an optimum fuel/air ratio for every operating condition of the internal combustion engine.

Means having such a sensor flap are known, control of the manner of operation of the sensor flap upon the starting of the internal combustion engine being either electromagnetic or pneumatic in order to permit an enriched fuel/air mixture to arrive at the individual internal combustion engine chambers upon starting.

SUMMARY OF THE INVENTION

An object of the present invention is to create a regulating device of the aforementioned type which, regardless of the adjustment of the throttle valve upon the starting of the internal combustion engine, provides assurance that the engine will be fed only the amount of fuel necessary so that errors on the part of the driver of a vehicle upon starting are without effect on the proper functioning of the regulating device and the latter therefore at all times permits the engine to start reliably.

This object is achieved in accordance with the invention by providing a channel connected on the one end with the outside air and discharging at the other end into the air intake line between the sensor flap and the throttle valve. The channel has at the place of discharge a closure flap which is urged by a spring into the open position and cooperates, via a first linkage means including a rod, with the sensor flap. When the closure flap is open, the sensor flap is in the closed position; when the sensor flap is moved out of the closed position, the closure flap is in the closed position, the sensor flap being held in closed position during the starting of the internal combustion engine by the sensor-flap closure spring and in addition by the closure-flap opening spring. Upon starting the engine with the throttle valve open, the sensor flap is movable against the action of the sensor flap and closure-flap springs from the closed position without opening of the air intake conduit but rather by closing the closure flap and adjusting the fuel quantity metering device for larger delivery. Furthermore, the closure flap, after starting of the internal combustion engine and upon the obtaining of a given vacuum in the air intake line between the internal combustion engine and the throttle valve, is swingable into closed position by a vacuum capsule acting through a second linkage means with displacement of the mechanism for the release of the sensor flap from the closure flap opening spring.

In this way, dependable starting of the internal combustion engine is assured in all cases, i.e., both with the throttle valve duly closed and with it open.

In the former case the air (which is necessary for the combustion of the fuel supplied by the fuel quantity metering device present in idling position in the engine chambers) is drawn in through the idle-air bypass by the internal combustion engine driven by the starter. The internal combustion engine starts and idles with the throttle valve still closed and the drawing in of the necessary combustion air through the idle air bypass. When a given vacuum is reached in the air intake line between the throttle valve and the internal combustion engine, the closure flap is moved into the closed position and the sensor flap is freed from the additional load by the closure flap opening spring so that it can carry out its normal control function.

In the second case, the required combustion air is drawn in by the internal combustion engine driven by the starter through the channel which bypasses the sensor flap which is held closed by the sensor flap closure spring and in addition by the closure flap opening spring. The two springs prevent displacement of the sensor flap out of the closed position and thus also the displacement of the fuel quantity metering device out of the idling position. The internal combustion engine starts up and when a given vacuum is reached in the air intake line between the throttle valve and the internal combustion engine, the closure flap moves into the closed position, while at the same time the sensor flap is freed from the additional load by the closure flap opening spring, so that it can fulfill its normal control function.

As a rule, the throttle valve is opened by the driver upon starting when the internal combustion engine, after repeated or lengthy startings with the throttle valve closed, has not started. A relatively large amount of fuel has then accumulated in the internal combustion engine chambers. If the internal combustion engine fires in this condition with the throttle valve open, it then races until the accumulated fuel has been consumed. In this connection, a vacuum is produced in the air intake line on the side of the closed sensor flap facing the internal combustion engine such that the sensor flap swings against the action of the sensor flap closure spring and the closure flap opening spring swings out of the closed position, so that the closure flap closes and the fuel quantity metering device is adjusted to a larger delivery. In this connection, the sensor flap does not open the air intake line.

Thus, the fuel/air mixture which passes into the engine chambers is prevented, because of the large quantity of air as compared with the quantity of fuel supplied by the fuel quantity metering device in the idle position thereof, which air passes through the channel bypassing the closed sensor flap into the air intake line, from being so impoverished after combustion of the fuel collected in the engine chambers that the internal combustion engine comes to a stop. Rather, the engine continued to operate. If the throttle valve is now closed, the engine idles, and the necessary combustion air is drawn in through the idle air bypass and the sensor flap is again in closed position, while the closure flap is again open. When a given vacuum is reached in the air intake line between throttle valve and engine, the closure flap is moved into closed position and the sensor flap is freed of the additional load by the closure flap opening spring, so that it can carry out its normal control function.

The closure flap is preferably connected via a lag mechanism with the vacuum capsule connected to the air intake line between engine and throttle valve, the lag mechanism being capable of being pushed together upon the starting of the engine with an open throttle valve by the sensor flap moving out of the closed position. In this connection, the lag mechanism between the closure flap and the vacuum capsule can advantageously consist of an arm acting on the closure flap or a lever arm thereof and a shaft, the arm being displaceably seated at the end remote from the flap on the shaft which is connected with the diaphragm of the capsule andhas an end stop. The arm and shaft have a total length such that when the diaphragm is arched away from the closure flap, the closure flap is closed.

The lag mechanism also prevents the closure flap from being urged in the opening direction upon a sudden opening of the throttle valve in the air intake line during the operation of the engine, the vacuum collapsing between the engine and throttle valve. The same purpose is served by the arrangement in accordance with the invention of a one-way choke which throttles in the direction towards the vacuum capsule in the line between the vacuum capsule and the air intake line.

The closure flap is preferably connected with a swingable curved cam piece on which a roller on the sensor flap travels. The travel surface of the cam piece when the closure flap is closed extends concentrically from the axis of swing of the sensor flap, and the cam piece when the closure flap is open is pressed against the roller by the spring which urges the closure flap into open position.

The sensor flap is advantageously connected via a cable with the tension spring for urging into the closed position, the cable extending over a pulley which is coaxial with the axis of swing of the sensor flap. In this way there is assured a linear dependence between the position of swing of the sensor flap and the spring loading thereof.

If the sensor flap cooperates via a swingable double-armed lever with the fuel quantity metering device, then, as an advantageous further development of the invention, the axis of swing of the lever is movable by means of a vacuum capsule which is connected to the air intake line between throttle valve and engine in such a manner that the lever swings around the point of connection with the sensor flap and brings the metering device into the zero-delivery position. In this manner, the conditions upon engine braking are taken into consideration. A considerable vacuum is then produced in the direction of flow of the intake air behind the throttle valve. When it reaches a given value, for instance a 7 m water column, the vacuum capsule swings the double-armed lever in such a manner that the fuel metering device does not feed any fuel to the internal combustion engine chambers.

In order to take the temperature of the intake air into account, a bimetallic element may be arranged between the sensor flap and an arm movable around its pivot, which arm is connected with the fuel metering device.

It has also proven advantageous for the initial tension of the spring which urges the sensor flap into closed position to be variable as a function of the vacuum in the air intake line between the throttle valve and the sensor flap.

The inner cross-section of the air intake line is preferably so developed in the region of swing of the sensor flap that upon the swinging of the sensor flap from the closed position, at first no change in the free cross-sectional area takes place, after which this free cross-sectional area increases in proportion to the angle of swing.

In accordance with a final characteristic feature of the invention, the sensor flap can rest in its closed position against an elastically resilient stop. In this way damage to the apparatus is avoided in case of a sudden increase in pressure in the air intake line between the throttle valve and the sensor flap.

BRIEF DESCRIPTION OF THE DRAWINGS

Two embodiments of the arrangement of the invention are described below by way of example with reference to the accompanying drawings in which:

FIG. 1 is a longitudinal section through that part of the air intake line of a mixture-compressing internal combustion engine in which the throttle valve and the device in accordance with the invention are provided;

FIG. 2 is a side view partially in axial section, corresponding to FIG. 1;

FIG. 3 is a part of the side view of FIG. 2, in which the control device is in a different position;

FIG. 4 shows a part of the longitudinal section of FIG. 1 through another embodiment of the invention;

FIG. 5 is a view of the section along the line V--V of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the air intake line 1 in which air can flow in the direction indicated by the arrow 2 from an air filter (not shown) to a mixture-compressing internal combustion engine (also not shown), there is provided a throttle valve 4 which is swingable about a horizontal pin 3 and can be adjusted as desired by the operator, this being generally done by means of a foot-actuated, so-called gas pedal. Between the throttle valve 4 and the internal combustion engine (not shown), there is provided the ordinary idle air bypass 4' via which the required quantity of combustion air passes into the air intake line 1 when the engine is idling, the throttle valve 4 being closed.

Furthermore, within the air intake line 1, in the direction indicated by the arrow 2, in front of the throttle valve 4, there is arranged a sensor flap 5 which is fastened to a shaft 6 rotatably supported inthe air intake line 1. On the shaft 6 there is keyed, outside the air intake line 1, a pulley 7 to which there is fastened at 8 a cable 9 which acts on a tension spring 10.

The end of the tension spring10 facing away spring 10 the cable 9 is fastened to the diaphragm of a vacuum capsule 11 which is connected via a line 12 with the air intake line 1 between the throttle valve 4 and the sensor flap 5. The initial tension of the tension spring 10 is in this way variable as a function of the vacuum in the air intake line 1 between the throttle valve 4 and the sensor flap 5.

The sensor flap 5 is swingable in the air intake line 1 around the longitudinal axis of the shaft 6 between the two positions shown in solid and in dashed line respectively in FIG. 1, namely in the direction of the arrow 2 against the action of the tension spring 10 as the result of a higher pressure in front of the sensor flap 5 and a lower pressure behind the sensor flap 5, the angle of swing of the sensor flap 5 from the position shown in solid line in FIG. 1 being proportional to the force exerted by the spring 10 on the sensor flap 5, and thus on the amound of said difference in pressure. This linear dependence is assured by the pulley 7 and the cable 9 between sensor flap 5 and spring 10.

In the wall of the air intake line 1 there is provided a channel 13 one end of which is in communication with the atmosphere, while the other end is provided at the place of discharge thereof into the air intake line between the sensor flap 5 and the throttle valve 4 with a closure flap 14. The latter is fastened to a shaft 15 rotatably supported in the air intake line 1 and can be swung between the position shown in solid line in FIG. 1 and the closed position shown in dashed line, in cooperation with the sensor flap 5 in such a manner that the sensor flap 5 is in closed position when the closure flap 14 is open and, conversely, the closure flap 14 is closed when the sensor flap 5 is moved out of the closed position, as shown in FIG. 1. In this connection the closure valve 14 is connected with a vacuum capsule 17 connected to the air intake line 1 via a line 16 behind the throttle valve 4, as seen in the direction of the arrow 2, the vacuum capsule serving to close the closure flap 14 and to release the sensor flap 5 from an additional load which is still to be described when the closure valve 14 is open, in case a given vacuum is reached in the air intake line 1 behind the throttle valve 4, as seen in the direction of flow.

As is particularly clear from FIGS. 2 and 3, a double-armed lever 18 is fastened to the shaft 15 outside the air intake line 1. A tension spring 19 fastened at 20 to the air intake line acts on the end of one of the lever arms. The spring 19 urges the closure flap 14 via the lever 18 and the shaft 15 into the open position shown in solid line in FIG. 1.

To the end of the other arm of lever 18 there is pivoted an arm 21 which is seated displaceably at the end remote from the flap on a shaft 24 which is connected with the diaphragm 22 of the vacuum capsule 17 and has an end stop 23. In this connection there is provided in the line 16 between the vacuum capsule 17 and the air intake line 1 a one-way throttle 25 which throttles in direction towards the vacuum capsule 17 and which, in accordance with FIG. 2, comprises a movable piston 26 which together with an opening in the throttle housing forms an annular throttle slot 27 the size of which can be varied by a setscrew 28 on which a pin-shaped extension of the piston 26 rests.

Between spring 19 and shaft 15 there is pivoted to the lever 18 a rod 29 which is pivotally connected at the other end to a curved cam piece 30. The cam piece 30 has a travel path 31 curved in the shape of a circular arc and is swingably supported around a shaft 32 on the outside of the air intake line 1.

With the cam piece 30 there cooperates a roller 33 moving on the cam path 31. The roller 33 is rotatably supported on the free end of an arm 34 which is fastened on the shaft 6 of the sensor flap 5 outside the air intake line 1. In the closed position of the sensor flap 5 shown in solid line in FIG. 1 the arm 34 assumes the position shown in FIG. 2, the roller 33 being pressed against a stop 35 which is swingable around a shaft 36 outside of the air intake line 1 and is pressed against a screw 39 by a tension spring 38 acting at 37 on the outside against the air intake line 1. The screw 39 can be turned in a lug 40 on the outside of the air suction line 1 to adjust the stop 35.

With the shaft 6 of the sensor flap 5 there is connected a cam disk 41 by means of which a device for metering the quantity of fuel to be fed to each chamber of the internal combustion engine (not shown) in order to obtain an optimum fuel/air mixture for every condition of operation of the internal combustion engine is controlled. For example, this device may be a rotary distributor for distributing the fuel, fed with constant pressure, to the individual chambers of a mixture-compressing injection internal combustion engine which has a cylindrical distributor rotor with an approximately triangular distribution groove in the cylindrical surface and a distributor stator which are displaceable axially with respect to each other in order to adjust the duration of the emergence of fuel at the individual places of delivery.

The cam disk 41 in the closed position of the sensor flap 5 which is shown in solid line in FIG. 1, the roller 33 being pressed against the stop 35, assumes the idle position shown in FIG. 2. Over the cam edge 44 of the cam 41 there moves a roller 45 arranged on one end of a double-armed lever 46 the other end of which acts on the setting member 47 of the aforementioned fuel metering device, which is not shown in detail.

The double-armed lever 46 is pivoted, swingable around a shaft 48, to another double-armed lever 49. The lever 49 is supported for rotation around a shaft 50 on the outside of the air intake line 1 and its second arm is connected via a rod 51 to a vacuum capsule 52. The latter is connected via a line 53 with the air intake line 1 between throttle valve 4 and the internal combustion engine (not shown). The pivot pin 48 of the lever 46 is movable by means of the vacuum capsule 52 in the manner that the lever 46 swings around the point of connection with the sensor flap 5, i.e., in the present case around the roller 45, and displaces the member 47.

The regulating device of the invention operates in the following manner. Before the start of the internal combustion engine (not shown in the drawings), the device is in the position shown in FIGS. 1 and 2. The sensor flap 5 is in this case held in closed position by the tension spring 10, the roller 33 of the sensor flap 5 resting against the stop 35. The curved cam piece 30 is swung by the spring 19 via the lever 18 and the rod 29 upwards so that the roller 33, and thus the sensor flap 5, are urged also by the spring 19 into closed position. The closure flap 14 is held open by the lever 18. The roller 45 of the double-armed lever 46 is pressed by a compression spring 54 against the cam edge 44 of the cam 41 connected with sensor flap 5, so that the adjustment member 47 is in idle position, and the internal combustion engine can be fed the quantity of fuel necessary for starting. The vacuum capsules 11, 17 and 52 are in neutral position since not acted on by any vacuum.

If the internal combustion engine is now started with the throttle valve 4 closed, as shown in solid lines in FIGS. 1 and 2, it then draws in the necessary quantity of combustion air via the idle air bypass 4' and after firing continues to idle with the throttle valve 4 closed. As soon as a given vacuum is reached in the air intake line 1 behind the throttle valve 4, as seen in the direction of the arrow 2, the vacuum capsule 17 becomes active and closes the closure flap 14, the cam curve 30 at the same time being swung into the position shown in FIG. 3 in which its cam path 31 is concentric to the pivot shaft 6 of the sensor flap 5 and the sensor flap 5 and its roller 33 are freed from the additional load by the spring 19, so that the sensor flap 5 is acted on only by the spring 10 and can exert the normal control function.

If instead of this the internal combustion engine is started with the throttle valve 4 open, as shown in dashed lines in FIGS. 1 and 2, then air flows into the air intake line 1 through the channel 13 which bypasses the closed sensor flap 5 and is opened by the closure flap 14. The sensor flap 5 remains held in closed position by spring 10 and in addition by the spring 19 via the cam curve 30, so that also the cam disk 41 remains in the position shown in FIG. 2 and furthermore the displacement member 47 remains in the idle position shown in FIG. 2.

As soon as there is reached in the air intake line 1 behind the throttle valve 4, as seen in the direction of the arrow 2, a given vacuum which acts via the line 16 with one-way throttle 25 on the vacuum capsule 17, the capsule via the shaft 24 with end stop 23 and via the arm 21 pulls the double-arm lever 18 against the action of the spring 19 into the position shown in FIG. 3, so that the closure flap 14 assumes the closed position shown in dashed line in FIG. 1 and the channel 13 is closed. Arm 21 and shaft 24 have such a total length that with the diaphragm 22 of the vacuum capsule 17 arched away from the closure flap 14, flap 14 is closed.

Furthermore, as can be noted from FIG. 3, the cam curve 30 is so swung via the rod 29 by lever 18 that the travel path 31 extends concentrically to the shaft 6 of the sensor flap 5. The additional loading of the roller 33 and thus of the sensor flap 5 by the spring 19 is therefore eliminated, and the sensor flap 5 can assume its normal control function, i.e., swing against the action alone of the tension spring 10 between the two positions shown in straight and dashed lines in FIG. 1, due to the difference resulting, upon operation of the internal combustion engine, between the originally static pressures and then dynamic pressures in front of and behind the sensor flap 5, the instantaneous position of swing of the sensor flap 5 being proportional to the instantaneous value of the pressure difference. The sensor flap 5 displaces the cam disk 41 in corresponding manner, so that the displacement member 47 of the fuel metering device (not shown in detail) is displaced via the double-arm lever 46. This can be noted from FIGS. 2 and 3 in which the position of the displacement member 47 is indicated in dot-dash lines in FIGS. 2 and 3.

As already mentioned, the arm 21 is displaceably guided on the shaft 24. In this way the following results are obtained. If upon repeated or lengthy unsuccessful attempts to start the internal combustion engine with the throttle valve closed, a certain supply of fuel collects in the internal combustion engine chambers and starting with open throttle valve is now attempted by the driver, the vehicle after firing races due to the supply of fuel and the air entering in ample quantity through the channel 13. In this way there is produced behind the feeler flap 5, as seen in the direction of the arrow 2, a vacuum which is sufficient to swing the sensor flap 5 in opposition to the action of the two springs 10 and 19 out of the closed position shown in solid line in FIG. 1. The cam curve 30, the rod 29 and the lever 18 are swung by the roller 33 of the arm 34 out of the position shown in FIG. 2 into the position shown in FIG. 3, so that the closure flap 14 assumes the closed position shown in dashed line in FIG. 1, and therefore no air can pass any longer through the channel 13 into the air intake line 1, and so that the displacement member 47 is set to a larger delivery of the metering device (not shown). In this way the fuel/air mixture fed to the internal combustion engine chambers after consumption of the supply of fuel in them cannot become so lean that the vehicle comes to a stop. Upon the swinging of the sensor flap 5, the latter does not release the air intake line 1, as will be explained below.

Furthermore, in case of an abrupt opening of the throttle valve during the operation of the internal combustion engine in connection with which all vacuum disappears behind the throttle valve 4, as seen in the direction of flow, and the diaphragm 22 of the vacuum capsule 17 moves from the position shown in FIG. 3 into the position shown in FIG. 2, the lag mechanism 21, 24 prevents the arm 21 from being carried along and the lever 18 from being swung, which would lead to an opening of the closure flap 14 and an actuation of the arm 34 with roller 33 via the cam curve 30. The desired behavior is supported by the one-way throttle 25 in the line 16 to the vacuum capsule 17 which in the case described provides assurance that the vacuum present previously in the vacuum capsule 17 will be only slowly destroyed and the diaphragm 22 moves correspondingly slowly from the position shown in FIG. 3 into the position shown in FIG. 2.

As explained above, the pivot pin 48 of the double-armed lever 46 is movable. Upon push operation of the internal combustion engine provided with the arrangement in accordance with FIGS. 1 to 3, i.e., upon downhill travel of the corresponding motor vehicle, for instance, the throttle flap 4 is closed, as shown in FIGS. 1 and 2. The internal combustion engine is driven from the vehicle and produces a relatively strong vacuum behind the throttle valve 4 in the direction of flow of the intake air. As soon as the vacuum assumes a given value, for instance exceeds 7 m water column, the vacuum capsule 52 responds and pulls the arm 51. The double-armed lever 49 swings around the shaft 50, so that the lever 46 swings to the right around the roller 45 resting against the cam disk 41 out of the position shown in FIG. 2 and brings the adjustment member 47 from the idle position into the zero-delivery position in which all feed of fuel to the internal combustion engine is interrupted by the fuel metering device (not shown).

The inner cross-section of the air intake line 1 is developed rectangularly in the region of swing of the sensor flap 5, as can be noted from FIG. 5. The shape of the sensor flap 5 is correspondingly rectangular so that in the closed position shown in solid line in FIG. 1 the inner cross-section of the air intake line 1 is closed. The rectangular inner cross-section of the air intake line 1 is furthermore so developed in the region of swing of the sensor flap 5 that upon swinging of the sensor flap 5 from the closed position at first no change in the free cross-sectional area takes place, whereafter this free cross-sectional area increases with an increase of swing of the sensor flap 5. This can be noted from FIG. 1. During a swinging of the sensor flap 5 from the position shown in solid line into the position 55 shown in dash-dot line, there is no change in the slow between the lower edge of the sensor flap 5 and the adjacent surface of the inner cross-section of the air intake line 1. Only after this does the slot increase with further swinging of the sensor flap 5 in such a manner that at every angle of swing of the sensor flap 5, the free area of the slot is proportional thereto.

The embodiment in accordance with FIGS. 4 and 5 corresponds in structure and operation to that of FIGS. 1 to 3, aside from the fact that in order to take into consideration the temperature of the air which is drawn in upon the displacement of the adjustment member 47 by the lever 46 and the cam disk 41, special measures are taken, namely a coil-spring-like bimetallic element 57 is inserted between the sensor flap 5 and a sensor arm 56 movable around the pivot axis thereof, the arm 56 being connected with the fuel metering device.

The shaft 6 on the sensor flap 5 on which the pulley 7 is keyed outside the air intake line 1 has within the air intake line 1 a larger outside diameter and a longitudinal bore 58. In said bore there is rotatably supported a shaft 59 to which the movable arm 56 is fastened. The shaft 59 extends out of the air intake line 1 and has at its free end the cam disk which is keyed on in fixed position. Pin 6 and shaft 59 are rotatably supported in the air intake line 1 and in addition turnable with respect to each other. The pin 6 therefore does not extend completely transversely through the air intake line 1, as can be noted particularly clearly from FIG. 5.

The bimetallic element 57 between the sensor flap 5 and the movable arm 56 expands to a greater or lesser extent depending on the temperature of the air drawn in so that the movable arm 56 is swung to a greater or lesser extent with respect to the sensor flap 5. The instantaneous position of rotation of the cam disk 41 thus corresponds at the same time to the instantaneous angular position of the sensor flap 5 in the air intake line 1 and the instantaneous angular position of the movable arm 56 with respect to the sensor flap 5.

Claims

What is claimed is:

1. In an apparatus for regulating the feed of fuel to a mixture-compressing internal combustion engine having an air intake line; a sensor flap; a first spring means coupled to said sensor flap for urging said sensor flap into its closed position; a throttle valve positioned within said air intake line, said throttle valve being interposed between the internal combustion engine and said sensor flap; and metering means coupled to said sensor flap for metering the quantity of fuel to be fed to each chamber of the internal combustion engine in order to obtain an optimum fuel air mixture for each operating condition for the internal combustion chamber; the improvement comprising

a. a closure flap positioned in a channel in the wall of said air intake line for opening and closing said channel, said channel having one end connected to the atmosphere and the other end discharging into said air intake line between said sensor flap and said throttle valve,

b. second spring means,

c. first linkage means coupling said second spring means to said closure flap and said sensor flap, said linkage and second spring means closing said sensor flap when said closure flap is open and closing said closure flap when said sensor flap is moved out of its closed position, said sensor flap being held during starting of the internal combustion engine in its closed position by said first and second spring means,

d. first vacuum means responsive to the vacuum in said air intake line between the internal combustion engine and said throttle valve, and

e. second linkage means coupling said first vacuum means to said closure flap and to said first linkage means, said closure flap being closed by operation of said first vacuum means through said second linkage means upon the reaching of a given vacuum in said air intake line and said sensor flap being disengaged from said second spring means by the operation of said first vacuum means through said first and second linkage means.

2. An apparatus as defined by claim 1 wherein said second linkage means comprises a shaft coupled to said first vacuum means and an arm displaceably mounted on said shaft, said arm being capable of displacement on said shaft when said sensor flap is moved out of the closed position.

3. An apparatus as defined by claim 2 wherein said first vacuum means comprises a capsule having a diaphragm secured to the shaft of said second linkage and wherein said shaft has an end stop for limiting the displacement of the arm of said second linkage, the shaft and arm of said second linkage means having a total length such that when the diaphragm of said capsule is curved away from said closure flap, said closure flap is closed.

4. An apparatus as defined by claim 1 wherein a one-way throttle is provided in a line coupling said first vacuum means to said air intake line between the internal combustion engine and said throttle valve, said one-way throttle throttling in the direction toward said first vacuum means.

5. An apparatus as defined by claim 1 wherein said first linkage means comprises a roller coupled to said sensor flap; a swingable curved cam piece on which said roller travels coupled to said closure flap and said second spring means, the travel path of the curved cam piece when the closure flap is closed extending concentrically to the pivot axis of said sensor flap, said cam piece being pressed against said roller by said second spring means when said closure flap is open.

6. An apparatus as defined by claim 1 wherein said sensor flap is pivotally mounted on a shaft and which further comprises a pulley mounted coaxial with said shaft and a cable passing over said pulley connecting said sensor flap to said first spring means.

7. An apparatus as defined by claim 1 which further comprises a second vacuum means responsive to the vacuum in said air intake line between the internal combustion engine and said throttle valve and wherein said metering means is coupled to said sensor flap by a swingable double-armed lever having a pivot shaft coupled to said second vacuum means, said lever swinging around the point of connection with said sensor flap to bring said metering means into position for zero delivery.

8. An apparatus as defined by claim 1 which further comprises a sensor arm movable around the pivot axis of said sensor flap and coupled to said metering means, and a bimetallic element positioned between said sensor flap and said sensor arm, said bimetallic element compensating for the temperature of the air drawn into said air intake line.

9. An apparatus as defined by claim 1 which further comprises third vacuum means responsive to the vacuum in said air intake line between said sensor flap and said throttle valve coupled to said first spring means, the initial tension of said first spring means being variable as a function of the vacuum in said air intake line between said sensor flap and said throttle valve.

10. An apparatus as defined by claim 1 wherein the inner cross-section of said air intake line in the region of swing of said sensor flap is so developed that upon the swinging of the said sensor flap out of the closed position there is no initial change in the free cross-sectional area, thereafter said free cross-sectional area increasing in proportion to the angular displacement of said sensor flap.

11. An apparatus as defined by claim 1 which further comprises an elastically resilient stop, said sensor flap in its closed position resting against said stop.