JPS5846654B2 - Boost pressure control device for supercharged engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a supercharged engine, particularly a supercharged engine in which a supercharger provided in an intake passage is driven by an exhaust turbine provided in an exhaust passage. This invention relates to a pressure control device.

Conventionally, in the above type of supercharged engine, in order to control the supercharging pressure, a bypass passage that bypasses the exhaust turbine is provided in the exhaust system, and when the intake pressure downstream of the supercharger exceeds a predetermined value, A so-called wastegate system is employed in which the bypass passage is opened to divert part of the exhaust gas from the exhaust turbine to reduce the driving force applied to the supercharger.

One method is to provide a pressure-responsive valve in the bypass passage, connect its pressure chamber to an intake passage located downstream of the supercharger, and open and close the pressure-responsive valve using the pressure in the intake passage to pass through the bypass passage. There is a method of adjusting the displacement (see Japanese Patent Laid-Open No. 50-65712).

However, since the intake pressure repeats small fluctuations even during steady state, in the above method, the pressure-responsive valve also fluctuates in accordance with the fluctuations in the intake pressure, and the pressure-responsive valve opens and closes frequently, causing damage. However, it also has the disadvantage that the rotational speed of the exhaust turbine changes and the intake pressure tends to become unstable.

As a result of various studies on this point, the inventor of the present invention found that if a restriction is provided in the pressure passage connecting the pressure chamber of the pressure-responsive valve and the intake passage, the minute pressure fluctuations will be alleviated by the restriction, and the pressure-responsive valve We focused on the fact that it can prevent frequent opening and closing.

However, if the above-mentioned method is used, the responsiveness of the pressure-responsive valve deteriorates, so the pressure-responsive valve cannot be activated quickly during engine transients, and if the engine speed drops below a predetermined value, the bypass will be bypassed for a while. The opening of the passage does not change,
The problem is that the exhaust turbine rotates at high speed due to inertia, and the intake pressure in the intake passage increases beyond a predetermined value.

The present invention has been made to solve the above-mentioned problems, and includes a first pressure passage having a throttle and a second pressure passage that bypasses the throttle. A supercharger equipped with a control valve that opens when the intake pressure fluctuates significantly (when the intake pressure fluctuates significantly) so that the intake pressure immediately acts on the pressure-responsive valve from the second pressure passage during engine transients to vary the bypass flow rate. The purpose of the present invention is to provide a supercharging pressure control device for an engine with an engine.

Next, the present invention will be explained according to the drawings which are examples.

In FIG. 1, 1 is an engine, 2 is an intake passage, and 3 is an exhaust passage.
An exhaust turbine 5 for driving the supercharger 4 is provided.

6 is a bypass passage, and this bypass passage 6 is provided in the exhaust passage 3 so as to bypass the exhaust turbine 5, and a pressure-responsive valve 7 is provided in the middle thereof.

The pressure responsive valve 7 includes a spring 8 and a diaphragm 9, and the diaphragm 9 has a valve body 11 for opening and closing the bypass passage 6, and the pressure chamber 10 is connected to the intake passage 2.
A first pressure passage 1 having a throttle 13 downstream from the supercharger 4 of
Connected with 2.

Further, the first pressure passage 12 is provided with a second pressure passage 14 that bypasses the throttle 13, and this passage 14 is provided with a second pressure passage 14 that detects when the pressure fluctuation in the intake passage 2 exceeds a predetermined value. A control valve 15 is provided which is operated to open.

Note that 16 is a throttle valve. Since the present invention has the above configuration, during steady operation, the intake pressure acts on the pressure chamber 10 of the pressure responsive valve 7 via the first pressure passage 12, and in relation to the repulsive force of the spring 8, the intake pressure acts on the pressure chamber 10 of the pressure responsive valve 7. The body 11 has an opening degree corresponding to this, and a predetermined amount of exhaust gas is bypassed from the bypass passage 6.

Also, during this period, the intake pressure fluctuates slightly, but this pressure fluctuation is alleviated by the presence of the throttle 13 and transmitted to the pressure chamber 10, so the valve body 11 hardly operates.

On the other hand, when the intake pressure fluctuates with a differential pressure greater than a predetermined value, for example, when changing gears from second to third, the engine speed will temporarily drop significantly, but the exhaust turbine 5 will continue to rotate at high speed due to inertia. As a result, the intake pressure increases rapidly.

Therefore, the control valve 15 will open.

That is, the intake pressure is transferred from the second intake passage 14 to the pressure chamber 10.
The valve body 11 opens the bypass passage 6, reduces the driving force of the exhaust turbine 5, and immediately optimizes the intake pressure.

Note that the control valve 15 is then closed, and thereafter the valve body 11 is controlled by the intake pressure of the first pressure passage 12 as described above.

In FIG. 2, the control valve 15 is composed of a ball valve 17, and when the pressure in the intake passage 2 suddenly increases, the pressure causes the ball 17a to retreat against the repulsive force of the spring 17b. The suction pressure is immediately applied to the pressure chamber 10.

Note that the inner diameter d1 of the throttle 13 portion is set smaller than the inner diameter d2 of the second pressure passage 14.

In FIG. 3, the control valve 15 is constructed with an acceleration sensor 18, and is composed of a diaphragm 19, a spring 20, and a valve body 25, and a third pressure passage 23 branched from the first pressure passage 12 is connected to the pressure The chamber 21 is connected to a pressure chamber 22 via a throttle 24.

Therefore, as described above, if the intake pressure suddenly increases due to acceleration, the pressure in the pressure chamber 21 will immediately become higher than the pressure in the pressure chamber 22 due to the presence of the throttle 24, so the valve body 25 will be moved to the second pressure passage. 14, thereby opening the valve body 11.
will open the bypass passage 6.

In addition, in the case of FIGS. 2 and 3 as well, after a predetermined period of time has elapsed, the pressure chamber 21.
The pressure difference between the two valves disappears, and the ball 17a1 valve body 25
The pressure passage 14 will be closed.

In addition, in the embodiment, the pressure passage that communicates the intake passage 2 and the pressure chamber 10 is shown as being dispersed in the middle.
The first and second pressure passages 12, 14 may be connected to the intake passage 2 and the pressure chamber 10 independently of each other.

Further, in the above description, the case where the intake pressure increases is described, but it is clear that the present invention can be applied to the opposite case by just slightly changing the configuration.

As is clear from the above description, according to the present invention, the intake pressure in the steady state of the engine acts on the pressure-responsive valve that opens and closes the bypass passage while being relaxed by the restriction of the first pressure passage. , minute pressure fluctuations in intake pressure do not directly act on the pressure chamber of the pressure-responsive valve, and the valve body does not open and close frequently.

Moreover, during engine transients, the control valve opens immediately and the intake pressure acts on the pressure chamber, greatly opening and closing the bypass passage to vary the exhaust turbine driving force, so the boost pressure is always maintained at the desired level. can be controlled stably at the value of
Conventional drawbacks can be completely avoided.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing one embodiment of the boost pressure control device of the present invention, and FIGS. 2 and 3 are partial schematic diagrams showing other embodiments. 1...Engine, 2...Intake passage, 3
...Exhaust passage, 4...Supercharger, 5...
...Exhaust turbine, 6...Bypass passage,
7... Pressure responsive valve, 11... Valve body, 12... First pressure passage, 13... Throttle, 4...... First 2 pressure passages, 15.17, 18... control valve.

Claims (1)

[Claims] 1. A supercharger is provided in the intake passage, an exhaust turbine for driving the supercharger is provided in the exhaust passage, and a bypass passage is provided to bypass the exhaust turbine, and the bypass passage is opened by the pressure of the intake passage. In a supercharged engine equipped with a pressure-responsive valve that controls opening and closing, the pressure chamber of the pressure-responsive valve is connected downstream of the supercharger by a first pressure passage having a throttle and a second pressure passage that bypasses the throttle. The second pressure passage is connected to the intake passage, and the second pressure passage is connected to the second pressure passage during engine transients.
A supercharging pressure control device for a supercharged engine, characterized by being provided with a control valve that opens a pressure passage.