JPS6217107B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an air unbalance start flap valve located upstream of the delivery opening of the device for supplying the main air-fuel mixture and includes a throttle member that can be controlled by the operator. a control cam in a position corresponding to a predetermined minimum opening of the flap valve, the angular position of which can be adjusted by the operator and which is constantly pressed in the closing direction by an elastic return device; an air motor arranged to move the valve in the opening direction and energized by a pressure drop occurring during operation in a portion of the inlet passage located downstream of the throttle member when the throttle member is in the rest position; and in which the cam has a first portion controlling said predetermined minimum opening.

This type of carburetor is provided with a linkage which slightly opens the throttle member when the starting flap valve is closed, thereby converting the pressure drop generated by the engine connected to the carburetor into the main mixture supply. Convey to the opening of the device. The engine is then able to draw in the rich fuel-air mixture necessary for cold starting.

As soon as the engine self-starts, the concentration of the mixture must be reduced quickly or the engine will shut down and stop. An air motor operated by the pressure drop created in the intake manifold downstream of the main throttle member as the engine rotates is intended to perform this function.

Unfortunately, in most existing carburetors of the type described above, the air motor only performs the opening action when the flap valve is initially closed or slightly open. In all cases the air motor is
If the operating stroke is sufficient to operate the flap valve immediately after starting, there is a risk that the mixture will be too thin and the engine will stall when the flap valve is initially closed.

Moreover, in most conventional systems, the cam provides virtually constant concentration regardless of engine operating conditions. Correct operation now requires, for example, varying concentrations during idle operation and steady load on the one hand and during acceleration on the other hand. The cam provides too high a concentration for dry running and steady-state operation, which causes high fuel consumption and pollution risks, and provides too low a concentration for acceleration, which is not fully satisfactory in practice, so it is considered a compromise. Designed.

The present invention aims to eliminate the disadvantages of conventional vaporizers as mentioned above and to provide a simple and convenient form of the vaporizer.

According to the invention, a carburetor of the type described above is provided, in which the cam constitutes a stopper device for limiting the range of movement of the air motor from its rest position and has a second part for adjusting the minimum opening of the flap valve by the air motor. , and a third portion constituting a further stop that prevents the flap valve from opening by the air flow beyond a predetermined minimum opening depending on the position of the cam.

The invention will be better understood from the following description of its embodiment, given by way of example, of a vaporizer.

Referring to the drawings, the illustrated carburetor has air intake 2.
and a main air-fuel mixing supply device opening into the bench lily 3. The feeding device (not shown) is conventional.

The vaporizer throttle member 6 is mounted for rotation on the pin 7 and is formed as a butterfly valve arranged downstream of the opening of the feed device. The throttle member 6 can be moved by an operator-actuated acceleration control (not shown) which, when released, forces the throttle member 6 into the rest position shown in FIGS. 1-3. . The rest position of the throttle member 6 is the position in which the throttle member is held slightly open by a mechanical device when the operator is not pressing the accelerator pedal.
Although the mechanical device is not directly related to the present invention and will not be described, the mechanical device is configured to slightly change the rest position of the throttle member depending on whether the air unbalance starting flap valve 4 is in the closed position or not. ing.

The cold start device of the carburetor consists of an eccentric air unbalance start flap valve 4 mounted on a transverse pin 5 upstream of the delivery opening of the main air-fuel mixture supply.
has. The flap valve 4 is connected to a lever 8 carrying a pin 10 on which a roller 9 can rotate freely. It also includes a cam 11 mounted to rotate around a pin 15 fixed to the carburetor body.
, the position of which is controlled by a cable T terminating in a knob placed within reach of the operator. Before starting the engine at low temperature, the knob is moved sufficiently in the direction shown by the arrow in FIG.
Take the position shown in the figure and FIG.

The spring 12 is connected at one end to a peg 13 fixed to the lever 8 and at the other end to a peg 14 on the cam 11. The spring 12 moves the roller 9 forming the first stop device to the cam 1.
It serves to maintain rolling contact with the first portion 11a of 1. When the cable T is fully tensioned, the air flap valve 4 is urged by the spring 12 into the fully closed position. On the contrary, when the cable is moved sufficiently to the left, the flap valve 4 is pushed via the first part 11a, the roller 9 and the lever 8 into the fully open position.

The starter further includes an air motor 24 which partially opens the air flap valve as soon as the engine is in self-operation. The air motor 24 has a diaphragm 26 that divides the interior of the stationary casing into two chambers 27,28. The chamber 27 is exposed to atmospheric pressure, while the chamber 28, called the working chamber, is exposed to the throttle member 6.
A duct 29 is installed in the part of the introduction path 1 located downstream of the
is combined with

The air motor is operatively coupled to the flap valve 4 through a bell crank lever 20 which rotates freely about pin 5. The lever 20 is provided with a contact finger 21 adapted to cooperate with the part 8a of the lever 8, so that when the lever 20 is rotated clockwise and into contact engagement with the lever 8, continuing to move the lever 20 causes the lever 8 to move in the same direction. direction around pin 5. The lever 20 further carries a roller 22 which is adapted to rotate freely around the pin 23 and to come into contact with the second portion 11b of the cam 11 when the lever 20 moves clockwise. The lever 20 is connected by a rod 25 to the movable part of the air motor 24, so that when the chamber 28 receives a pressure drop sufficient to overcome the force of a return spring 30 placed within this working chamber 28, the diaphragm 26 in the clockwise direction.

The cam 11 has a third portion 11c, on which
The flap valve 4 is moved by the air motor 24 and rotatably receives the roller 9 when the flap valve 4 is about to open beyond the position determined by the contact of the roller 22 on the portion 11b. In the illustrated embodiment, portions 11a, 11c are formed by parallel sides of an elongated opening formed in cam 11.

The device operates as follows.

Before starting the engine at low temperatures, the operator fully pulls the cable T. The cam 11 then assumes the position shown in FIG. Spring 12 connects roller 9 to cam 11
is maintained in contact with the first portion 11a of. Flap valve 4 is in its fully closed position. The concentration is at its maximum when the engine is driven by the starting motor.

Immediately after starting the engine, the high pressure drop that appears in the inlet 1 downstream of the throttle element 6 is transmitted by the duct 29 to the chamber 28 of the air motor 24 and moves the rod 25 to the right in the figure. The lever 20 rotates clockwise around the pin 5 and its contact finger 21 moves the lever 8 against the force of the spring 12 until the roller 22 contacts the part 11b of the cam 11 and drives the lever 8. The operably connected flap valve 4 is partially opened so that the engine receives the required thin mixture. The other elements are in the positions shown in FIG.

As the temperature of the engine increases, the operator pushes in the cable T one after the other, which results in the intermediate position shown in FIG. 3, for example. The roller 22 is in motion when the cam 11
11b of the air motor 2, which causes a high pressure drop in the intake manifold to
4 to overcome the force of the spring 30. The contour of the portion 11b of the cam 11 is chosen such that during the movement of the cam 11 to reach the intermediate position, the lever 20 rotates further clockwise, thus forcing the flap 4 to assume a more open position.

Up to now, it has been assumed that the engine is running idle and the throttle member 6 is in its minimum open or rest position.

If the engine is loaded by opening the throttle member 6 as shown in FIG.
The pressure drop delivered by the air motor 24 to the air motor 24 will be insufficient to balance the forces of the springs 30 and 12. The rod 25 is pushed back to the left and the lever 20
rotates counterclockwise until the roller 9 contacts the first portion 11a of the cam.

It will be seen that the opening of the throttle member 6 then causes a closing movement of the flap valve 4, which provides the engine with the rich mixture it requires during its under-load operating conditions.

This effect causes the opening of the duct 29 in the inlet 1 to pass from the downstream side to the upstream side of the throttle element 6 as soon as the throttle element 6 opens from its rest position corresponding to the closing of the flap valve 4. Increased by placement.

As a result, during engine acceleration, flap valve 4
It is achieved that the mixture continues to thicken until it again assumes a more open position corresponding to a balance between the aerodynamic forces acting on the air imbalance starting flap valve and the action of the spring 12. In the illustrated embodiment, the new position of the flap valve is such that the roller 9 is positioned against the cam portion 11c as the flap valve attempts to open further.
cannot go beyond the position corresponding to the contact. In the portion 11c, the roller 22 is the second part of the cam 11.
It is designed so as not to prevent it from coming onto the portion 11b.

When operating engines supplied with a carburetor with a manually operated starting flap valve in cold operation, for each position of the manually operated cam there is a maximum opening (during cold or stable operation of the engine) on the one hand and a small opening during acceleration on the other hand. An aperture is obtained. The mixture supplied to the engine will be leaner immediately after start-up, unless the cam is set to operate at normal engine operating temperatures and the moving parts of air motor 24 are in full motion.

The present invention therefore overcomes the limitations of the prior art in uniformly using a mixture of the same concentration, which is often insufficient during acceleration at temperature during dry run.

[Brief explanation of the drawing]

1 is a simplified side view, partially in section, showing the elements of the carburetor of the present invention with the engine stopped and the start cam control knob in the cold start position; FIG. Figure 1 is similar to Figure 1, but the engine is started and running idle, and the cam occupies the same position as Figure 1. Figure 3 is also similar to Figure 1, but the engine is running idle. Fig. 4 is similar to Fig. 1, but the cam position corresponds to Fig. 3, but the diaphragm member is partially open. showing something. DESCRIPTION OF SYMBOLS 1... Introduction path, 2... Air intake port, 3... Bench lily, 4... Flap valve, 5... Pin, 6... Throttle member,
7... Pin, 8... Lever, 8a... Part, 9... Roller, 10... Pin, 11... Cam, 11a, b, c...
Part, 12...Spring, 13, 14...Peg, 15...Pin, 20...Lever, 21...Finger portion, 22...Roller, 23...Pin, 24...Air motor, 25...
Rod, 26...Diaphragm, 27, 28...Chamber, 29
...Duct, 30...Spring.

Claims (1)

Claims: 1. An inlet channel provided with an air unbalance starting flap valve located upstream of the delivery opening of the device for supplying the main air-fuel mixture and provided with a throttle member 6 which can be controlled by the operator. 1, a control cam 11 in a position corresponding to a predetermined minimum opening of the flap valve, the angular position of which can be adjusted by the operator and which is constantly pressed in the closing direction by an elastic return device 12; Air which is arranged to move the flap valve in the opening direction and which is energized by the pressure drop that occurs during operation in the part of the inlet passage which is arranged downstream of the throttle member when the throttle member is in the rest position. a motor 24, the cam 11 having a first portion 11a for controlling the predetermined minimum opening, the cam 11 having a stopper device for limiting the range of movement of the air motor from a rest position; a second portion 11b comprising and adjusting the maximum opening of the flap valve by the air motor; and another stopper for preventing the flap valve from opening by the air flow beyond a predetermined maximum opening depending on the position of the cam. A vaporizer characterized by having a third portion 11c. 2. A carburetor according to claim 1, wherein said cam is operatively connected to said flap valve by a resilient device, said resilient device being a member with said flap valve to said first portion of said cam. 9. A carburetor, characterized in that the flap valve is pushed towards a minimum open position determined by the contact of 9. 3. A carburetor according to claim 2, wherein the air motor 24 contacts a second lever 8 which is arranged to rotate about the axis of rotation of the flap valve and is drivingly connected to the flap valve. A carburetor characterized in that it is drivingly connected to a first lever 20 provided with a contact finger for driving the second lever and the flap valve in the opening direction. 4. In the carburetor according to claim 3, the second lever 8 supports the member 9 arranged to cooperate with both the first part and the third part of the cam. A vaporizer featuring: