JPS6246843Y2 - - Google Patents

Description

[Detailed description of the invention] This invention opens and closes the secondary side throttle valve of a dual carburetor installed downstream of the supercharger in an internal combustion engine equipped with a supercharger such as an exhaust turbo supercharger. This invention relates to a control device.

The secondary throttle valve in a dual carburetor is configured to open automatically when the primary throttle valve reaches a certain opening or increases in intake pressure. The supply of fuel to the secondary side of this dual carburetor does not start at the same time as the throttle valve on the secondary side opens, but when the throttle valve on the secondary side opens, a flow is generated on the secondary side. , the fuel supply on the secondary side starts from the moment the pressure in the ventilate part on the secondary side drops, so the fuel supply on the secondary side is delayed slightly from the opening of the secondary side throttle valve, and the fuel supply on the secondary side starts. A considerable amount of air will be sucked into the engine until the engine starts, and this tendency becomes more noticeable during acceleration when the throttle valve is opened rapidly.

On the other hand, recent supercharged internal combustion engines have adopted a system in which a carburetor is installed downstream of the supercharger. In the case of a double carburetor, the time when the secondary side throttle valve of the dual carburetor starts to open corresponds to when the supercharging pressure has increased to a certain extent, so the period until the start of fuel supply on the secondary side corresponds to the time when the secondary side throttle valve of the dual carburetor starts to open. The amount of air drawn into the engine is significantly greater than in a non-supercharged internal combustion engine. Therefore, when a dual carburetor is applied to a supercharged internal combustion engine, the intake air mixture to the engine becomes temporarily extremely lean when the secondary throttle valve begins to open during acceleration. This causes a so-called secondary shock in which the engine output temporarily decreases, resulting in a worsening of the acceleration feeling.

Therefore, Japanese Utility Model Application Publication No. 57-8329 as a prior art discloses that in a supercharged internal combustion engine, the secondary throttle valve in a dual carburetor installed downstream of the supercharger is connected to the downstream side of the primary throttle valve. In the diaphragm mechanism related to the intake pressure, which opens in response to the increase in the intake pressure, a throttle orifice is provided in the intake pressure transmission passage to the diaphragm mechanism to open the diaphragm mechanism in response to the increase in the intake pressure. By delaying the opening operation of the secondary throttle valve, the fuel supply on the secondary side follows the opening of the secondary throttle valve. Since the closure of the secondary throttle valve is delayed during deceleration and the engine braking effect is reduced, it is proposed that the intake pressure transmission passage be provided with a means for opening the diaphragm chamber of the diaphragm mechanism to the atmosphere during deceleration of the engine. are doing.

However, with this configuration, the secondary shock during engine acceleration can be avoided without impairing engine deceleration, and the acceleration feeling can be improved, but on the other hand, the delayed opening operation of the secondary throttle valve by the throttle orifice is , since acceleration is carried out until completion, the increase in engine output in the acceleration range is similarly delayed and acceleration performance deteriorates.
Furthermore, a means for opening the diaphragm chamber of the diaphragm mechanism to the atmosphere when the engine decelerates, that is, a means for detecting the deceleration state of the engine and a valve that switches the diaphragm chamber to the atmosphere based on this detection signal are required. This not only makes the structure extremely complicated, but also increases the installation space.

The present invention slows down the opening speed of the secondary throttle valve, which opens as boost pressure increases, so that when the engine decelerates, the secondary throttle valve closes without delay as boost pressure drops. By providing a delay means for only one direction, the structure is simplified and the space is reduced, while the delay of the opening operation of the secondary throttle valve is limited to the secondary shock area, and no secondary shock occurs. When the supercharging pressure rises to this range, the delay in the opening operation of the secondary throttle valve by the delay means is released, thereby reducing a drop in output when the engine accelerates.

The present invention will be explained below with reference to drawings of embodiments. In the drawings, 1 is an internal combustion engine equipped with an intake manifold 2 and an intake manifold 3, and 4 is an exhaust turbo supercharger directly connected to an exhaust turbine 5 and a blower compressor 6. In the intake passage 7 that connects the discharge side of the blower compressor 6 in the exhaust turbo supercharger 4 and the intake manifold 2, there is a surge tank 8 for eliminating pulsation and a dual carburetor 9. The surge tank 8 is provided on the upstream side, and the air cleaner 10 is connected to the suction side of the blower compressor 6.
Further, an exhaust passage 11 is provided on the inflow side of the exhaust turbine 5.
The exhaust manifold 3 and the exhaust pipe 12 to the atmosphere are connected to the outlet side of the exhaust turbine 5 through the exhaust manifold 3 and the exhaust turbine 5, respectively.

The primary side 13 of the dual carburetor 9 is equipped with a primary side throttle valve 14 which is opened by pressing an accelerator pedal (not shown), and the secondary side 15 is equipped with a secondary side throttle valve 16. We are prepared.

Reference numeral 17 denotes pressure response means for the secondary throttle valve 16, which employs a diaphragm mechanism in this embodiment.The pressure response means 17 includes a spring 18 that biases the secondary throttle valve 16 to normally close. On the other hand, the pressure in the intake passage 7 between the blower compressor 6 and the carburetor 9 or the intake passage 7 or the surge tank 8 on the downstream side of the carburetor 9 is transferred into the pressure chamber 19 through a first pressure transmission. By introducing the fluid through the passage 20, the secondary throttle valve 16 opens against the spring 18 when the pressure reaches a certain supercharging pressure equal to or higher than the atmospheric pressure. A throttle orifice 21 is provided in the first pressure transmission passage 20.
and a check valve 22 that opens only in the direction opposite to the direction of the intake passage 7 or the surge tank 8, that is, the direction to the pressure response means 17. A second pressure transmission passage 24 is provided in parallel with the pressure response means 17 and the intake passage 7 or the surge tank 8, and in the passage 24, the supercharging pressure from the blower compressor 6 is transmitted to the pressure response means 17 and the surge tank 8. A pressure opening/closing valve 25 is provided which opens the second pressure transmission passage 24 when the pressure reaches an appropriate level higher than the set value in the means 17.

In this configuration, in an operating range where the primary throttle valve 14 of the carburetor 9 is slightly opened, the amount of exhaust gas from the engine is small, and therefore the rotational speed of the supercharger 4 is low, and the pressure chamber 19 of the pressure response means 17 is The pressure acting on the pressure response means 17 does not exceed the set value, and the secondary throttle valve 16 is closed. However, when the opening degree of the primary throttle valve 14 is increased, the pressure response means 1
The pressure acting on the pressure chamber 19 of 7 gradually increases,
When the set value in the pressure responsive means 17 is exceeded, the secondary throttle valve 16 begins to open.

In this case, during normal acceleration when the primary throttle valve 14 is opened slowly, the pressure in the intake passage 7 or the surge tank 8 increases slowly, and the throttle orifice 21 in the first pressure transmission passage 20 Since the pressure is transmitted to the pressure response means 17 without being subject to delay restrictions due to During acceleration, the pressure rises rapidly, and the transmission of this sudden rise in pressure to the pressure response means 17 is delayed by regulation at the throttle orifice 21 in the delay means 23, so that the secondary throttle valve 16 is slower than the pressure rise speed. Since the secondary throttle valve 16 will be opened at
Due to the gradual opening operation of the secondary throttle valve 16, the fuel supply on the secondary side 15 can follow the opening operation of the secondary throttle valve 16. This makes it possible to reliably prevent the occurrence of secondary shocks.

When the opening degree of the secondary throttle valve 16 increases as the pressure increases and reaches a region where secondary shock does not occur, the pressure provided in parallel to the delay means 23 in the first pressure transmission passage 20 is increased. Since the on-off valve 25 opens to communicate with the second pressure transmission passage 24 and releases the delayed opening operation of the secondary throttle valve 16 caused by the restrictor orifice 21, the opening operation of the secondary throttle valve 16 will be performed thereafter. follows the pressure increase without delay, and a decrease in output due to the delayed opening operation of the secondary throttle valve 16 is prevented.

Furthermore, when the pressure in the intake passage 7 or the surge tank 8 drops during deceleration with the primary throttle valve 14 closed, this pressure drop causes the delay means 2 to
By opening the check valve 22 at 3, the drop in pressure is transmitted to the pressure response means 17 without delay,
Since the secondary throttle valve 16 closes quickly, it is possible to reliably prevent the engine braking effect from being diminished.

Note that even if the second pressure transmission passage is provided completely in parallel with the first pressure transmission passage, as shown by the dotted line in the figure, it may be provided so as to bypass only the delay means, as shown by the solid line. A similar effect can be obtained,
Moreover, the same effect can be obtained by a combination of the above two.

In summary, the present invention provides a supercharged internal combustion engine in which a dual carburetor is provided in the intake passage on the downstream side of a supercharger. A pressure responsive means for opening the throttle valve in response to an increase in pressure within the intake passage is provided, and a pressure response means is provided in a first pressure transmission passage connecting the pressure responsive means and the intake passage. A second pressure transmission passage is provided in parallel with the delay means to connect the pressure response means and the intake passage, and the pressure in the intake passage is maintained at a predetermined level in the passage. In this case, since a pressure opening/closing valve is provided to open the passage, it is possible to prevent secondary shock when the engine suddenly accelerates without impairing the effect of engine braking when the engine decelerates. Moreover, the delayed opening operation of the secondary throttle valve when the engine suddenly accelerates is
Only the area where secondary shock occurs, and when the area where secondary shock does not occur, the delayed opening operation of the secondary throttle valve is canceled, so the output when the engine accelerates is the same as the delayed opening operation of the secondary throttle valve. This is a significant improvement over the case where this is done over the entire acceleration range, and together with the absence of the secondary shock, the acceleration feeling can be improved.

Furthermore, the present invention does not require a means for detecting the deceleration state of the engine and a means for switching the diaphragm mechanism to communicate with the atmosphere based on this detection signal, unlike the prior art, so the structure is extremely simple. This has the effect of reducing the installation space, as well as being inexpensive and lightweight.

[Brief explanation of the drawing]

The drawings are diagrams showing embodiments of the present invention. 1...engine, 4...supercharger, 7...intake passage,
9...Dual carburetor, 13...Primary side, 15...
Secondary side, 14...Primary side throttle valve, 16...
Secondary throttle valve, 17...pressure responsive means, 2
0...first pressure transmission passage, 23...delay means,
21... Throttle orifice, 22... Check valve, 24
...Second pressure transmission passage, 25...Pressure opening/closing valve.

Claims (1)

[Scope of utility model registration request] In a supercharged internal combustion engine in which a dual carburetor is provided in an intake passage on the downstream side of a supercharger, a secondary throttle valve on the secondary side of the dual carburetor is connected to the pressure in the intake passage. A pressure response means is provided to open the throttle valve in accordance with the increase in pressure, and pressure is applied in a first pressure transmission passage connecting the pressure response means and the intake passage with a delay only in the direction of the pressure response means. A second pressure transmission passage is provided in parallel with the delay means to connect the pressure responsive means and the intake passage, and the passage is opened when the pressure in the intake passage exceeds a predetermined level. 1. A control device for a secondary throttle valve in a dual carburetor for a supercharged internal combustion engine, characterized in that it is provided with a pressure opening/closing valve that is activated.