JPS5945801B2 - Low-speed output compensation device for supercharged internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low-speed output compensation device for an internal combustion engine with an exhaust turbine supercharger.

As is well known, in an internal combustion engine equipped with an exhaust turbine supercharger, a supercharger is driven by exhaust pressure, and intake air is pressurized by the supercharger and fed into the engine to increase output.

However, when the engine rotates at low speed, the exhaust pressure is low, so the supercharger cannot be driven sufficiently, and conversely, the turbofan of the supercharger acts as suction resistance, resulting in a lack of intake air and a lack of output.

As a result, the torque curve of the engine becomes unfavorable for use in a vehicle, and the starting and acceleration performance is particularly poor on slopes and rough terrain.

The present invention has been devised in view of the above-mentioned drawbacks, and is equipped with a supercharger that bypasses the supercharger in the intake passage to suck in intake air during low speed rotation, thereby increasing the output at that time. It is an object of the present invention to provide an output compensation device for an internal combustion engine.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In the embodiment shown in FIG. 1, 1 is an air filter, 2 is an intake passage, 3 is an intake manifold, 4 is an exhaust turbine supercharger, and 5 is a part of the intake passage 2 before and after the supercharger 4. A bypass passage 6 is an on-off valve interposed at the outlet of the bypass passage 5.

This on-off valve 6 has one end of the valve body pivoted freely on a support shaft a, and is normally elastically moved in the direction of closing the outlet of the bypass passage 5 by a spring 7 disposed inside the bypass passage 5. It is energized and the bypass passage 5 is closed.

When the negative suction pressure in the intake passage 2 on the downstream side of the supercharger 4 increases, the valve body is attracted and rotated counterclockwise in the figure, and at this time it functions to open the Nonoi pass passage 5. .

Therefore, during low-speed rotation when turbocharging has no effect and the suction negative pressure in the intake passage 2 downstream of the supercharger 4 increases, the valve body is attracted against the elastic force of the spring 7 due to the suction negative pressure. The opening/closing valve 6 is opened by being rotated counterclockwise in the middle, and intake air is sucked in through the bypass passage 5, thereby compensating for the lack of intake air amount caused by the supercharger 4 acting as intake resistance. Since the amount of fuel injection can be increased in accordance with the increase in the amount of intake air, the output can be improved.

On the other hand, during high-speed rotation, the negative pressure is canceled by the discharge pressure of the supercharger 4, so the on-off valve 6 closes the bypass passage 5 by the force of the spring 7.

Therefore, supercharging by the supercharger 4 is performed as in the conventional case.

Therefore, the torque curve of the engine is improved as shown by the solid line in FIG.

Note that the broken line indicates a conventional torque curve.

Furthermore, during engine operation, the pressure in the intake passage 2 downstream of the supercharger 4 is mostly high, and there are few low-speed rotation periods during which the intake passage 2 is under negative pressure.

Therefore, by configuring the spring 7 to extend during the low-speed rotation period, the time required for the spring 7 to extend is reduced, deterioration of the spring 7 is suppressed, and durability is improved.

Furthermore, since the on-off valve 6, which is normally closed, is opened due to the generation of suction negative pressure, the on-off valve 6 is already in the closed state when supercharging pressure is generated, so that no discharge from the supercharger 4 occurs. There is no possibility that a part of the supercharged air will flow into the bypass passage 5 side.

Furthermore, since the spring 7 is arranged on the bypass passage 5 side rather than on the intake passage 2 side, there is an advantage that the spring 7 does not act as resistance to supercharging air.

As described above, when the engine speed is low, which is a problem in an internal combustion engine with an exhaust turbine supercharger, the present invention opens a passage that bypasses the supercharger to compensate for the lack of intake air amount, thereby improving the output. As a result, starting and acceleration performance on the slopes and uneven terrain described above can be improved, and exhaust gas conditions are also improved.

Furthermore, it goes without saying that the supercharging effect can be maintained during high speed rotation.

Furthermore, since the spring expands only at low speeds and little force is applied to the spring during most of the engine operation or when the engine is stopped, the spring has good durability.

In addition, since the on-off valve is closed when supercharging pressure is generated, there is no risk of supercharging air flowing back into the bypass passage, and since the spring is placed in the bypass passage instead of the intake passage, The spring does not create suction resistance during supercharging, allowing efficient supercharging.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of an embodiment of the device according to the present invention, and FIG.
The figure is a diagram showing a torque curve according to the invention. 2...Intake passage, 4...Supercharger, 5...
...Bypass passage, 6...Opening/closing valve, I.
·····spring.

Claims (1)

[Claims] 1. A bypass passage is provided that connects the front and rear of the turbocharger in the intake passage by bypassing the turbocharger, and at the exit of the bypass passage that connects to the intake passage on the downstream side of the turbocharger, it is normally placed in the bypass passage. An internal combustion engine with a supercharger is provided with an on-off valve that is held closed by the elastic force of a spring and opens against the elastic force of the spring in response to negative suction pressure in the intake passage when the engine is running at low speed. output compensation device.