JPH0214527B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a supercharged engine.

(Prior art) Some engines with superchargers are
There is a device that performs so-called partial supercharging as shown in Japanese Patent No. 69722. That is, some engines perform only natural intake until the middle of the intake stroke, and perform supercharging from the end of the intake stroke or from the beginning of the compression stroke to the middle of the compression stroke.

(Problems to be Solved by the Invention) Recently, devices have been considered that effectively utilize the intake inertia effect to improve the filling efficiency. When combining this inertia effect with partial supercharging, in the case of a reciprocating engine, in addition to the supercharging port opened and closed by the supercharging intake valve, there is also an auxiliary intake port opened and closed by the auxiliary intake valve in the combustion chamber of the engine. The port is opened, and the supercharging passage in which the turbocharger is installed is connected to this supercharging port, while the auxiliary passage that only performs natural intake is connected to the auxiliary port, thereby reducing the intake inertia effect due to natural intake. When the engine speed is low and the engine speed is small, suction is performed only through the supercharging passage (supercharging), and at high engine speeds where a large intake inertia effect can be expected, suction is performed from both the supercharging passage and the auxiliary passage. is possible.

By the way, if the suction from the auxiliary passage is selected and switched according to the engine speed as described above, the closing timing of the supercharging port will inevitably be the same as the closing timing of the auxiliary port due to partial supercharging. It will have to be much slower than that.

However, as mentioned above, if the closing timing of the supercharging port is later than the closing timing of the auxiliary port for partial supercharging, there is a problem that the charging efficiency is not sufficiently improved due to blowback at low engine speeds. will occur.

Therefore, an object of the present invention is to provide a supercharged engine that can effectively perform partial supercharging at high engine speeds while ensuring improved charging efficiency at low engine speeds. It is in.

(Means and effects for solving the problem) In order to achieve the above-mentioned object, in the present invention, the closing timing of the supercharging port is made variable according to the engine speed. In other words, at high engine speeds when it is necessary to effectively obtain partial supercharging, the closing timing of the supercharging port is set to be later than the closing timing of the auxiliary port, while at low engine speeds, the closing timing of the supercharging port is set to be later than the closing timing of the auxiliary port. The timing is set to be earlier than when the engine is running at high speed to ensure charging efficiency. Specifically, a supercharging port and an auxiliary port are opened in the combustion chamber of the engine, a supercharging passage in which a supercharger is arranged is connected to the supercharging port, and a natural suction port is connected to the auxiliary port. an auxiliary passage for performing the above-mentioned supercharging is connected, and a passage switching means is provided so that suction is carried out only through the supercharging passage when the engine is running at low speeds, and from both the supercharging auxiliary and the above when the engine is running at high speeds; a timing control means for setting the closing timing of the supercharging port to be earlier when the engine is running at low speeds than when it is at high speeds, and to be set to be later than the closing timing of the auxiliary port when the engine is at high speeds; The structure is such that the passage switching means and the timing control means are set to be switched in synchronization with each other.

(Example) Examples of the present invention will be described below with reference to the attached drawings.

In FIG. 1, reference numeral 1 denotes an engine body, and in this embodiment, the engine body 1 connects a crankshaft (not shown) as an engine output shaft via a connecting rod 4 by reciprocating movement of a piston 3 within a cylinder 2. It is a reciprocating type that is rotationally driven.

In the upper part of the combustion chamber 6 defined by the cylinder 2 and the piston 3, an auxiliary port 7, an exhaust port 8, and a supercharging port 9 are opened. The exhaust port 8 is opened and closed by an exhaust valve 11 at known timings via a timing cam (not shown) in synchronization with the rotation of the crankshaft. Also, supercharging port 9
are opened and closed by a supercharging intake valve 12, and the supercharging intake valve 12 is opened and closed in synchronization with the rotation of the crankshaft at a timing to be described later.

An auxiliary passage 13 is connected to the auxiliary port 7, and a supercharging passage 14 is connected to the supercharging port 9, and the upstream ends of these passages 13 and 14 are joined, and a common passageway upstream from this joining part is connected. The passage 5 is connected to an air cleaner 15, and an air flow meter 16 is connected in the middle thereof. This auxiliary passage 13
A shutter valve 17 for passage switching and an auxiliary throttle valve 18 are arranged in this order from the air flow meter 15 side. Further, in the supercharging passage 14, a turbo supercharger 1 is sequentially installed from the air flow meter 15 side.
A main throttle valve 20 that interlocks with the compressor wheel 19a of 9 and the sub-throttle valve 18 is provided.

On the other hand, an exhaust passage 21 connected to the exhaust port 8
, the turbine wheel 19 of the turbocharger 19
b is disposed, and when the turbine wheel 19b is rotated by the exhaust energy, the compressor wheel 19a is rotationally driven via the shaft 19c, and supercharging is performed. Also,
The exhaust passage 21 is provided with a bypass passage 22 that connects the turbine wheel 19b.
2, a waste gate valve 23 is disposed. This waste gate valve 23 is adapted to be driven by a pressure-operated actuator 24. That is, the actuator 24
is connected to the compressor wheel 1 via the passage 25.
Supercharger passage 1 between 9a and main throttle valve 20
4, and when the supercharging pressure reaches a predetermined value or more, the waste gate valve 23 is opened to prevent the supercharging pressure from rising to a predetermined value or more.

In the embodiment, the shutter valve 17 is opened and closed according to the exhaust pressure corresponding to the engine speed,
For this purpose, a pressure-operated actuator 26 is provided. This actuator 26 is connected to the exhaust passage 21 downstream of the bypass passage 22 via a passage 27, and opens the shutter valve 17 when the exhaust pressure exceeds a predetermined value, that is, when the engine speed exceeds a predetermined value. When the exhaust pressure is below a predetermined level, the shutter valve 17 is closed. Here, the opening/closing range of the shutter valve 17 is shown in FIG. 2, but in this embodiment, since it is controlled according to the exhaust pressure, not only the engine speed but also the engine load are taken into account. Therefore, the shutter valve 17 is opened at least when the engine speed is high and the load is high.

The supercharging intake valve 12 is driven to open and close by a crankshaft via a variable mechanism 28 serving as timing control means. The variable mechanism 28 changes the opening and closing timing of the supercharging intake valve 12, and is operated in conjunction with the opening and closing of the shutter valve 17. That is, the opening and closing of the shutter valve 17 is detected by the sensor 29, and the output signal from the sensor 29 operates the variable mechanism 28 (the actuator thereof), so that when the shutter valve 17 is open, it operates as shown by the broken line in FIG. The closing timing of the supercharging intake valve 12 is set later than the closing timing of the auxiliary intake valve 10. Conversely, when the shutter valve 17 is closed, the supercharging intake valve 12 closes at the third
As shown in the figure experiment, the shutter valve 17 is opened earlier than when it is opened. The closing timing of the supercharging intake valve 12 is set in the middle of the compression stroke when it is late, and it is set at a timing that almost coincides with the closing timing of the auxiliary intake valve 10 when it is early. The configuration of the variable mechanism 28 itself is known from Japanese Unexamined Patent Publication No. 59-65509, so detailed explanation thereof will be omitted.

In FIG. 1, 30 is a muffler, and fuel is supplied from a fuel injection valve (not shown) provided in only the supercharging passage 14 or in both the supercharging passage 14 and the auxiliary passage 13. There is.

Next, the operation of the above configuration will be explained.

First, in a high-speed, high-load range, the shutter valve 17 is opened, and suction is thereby performed through both the auxiliary passage 13 and the supercharging passage 14. At this time, the variable mechanism 28 performs partial supercharging in which the closing timing of the supercharging intake valve 12 is made later than the closing timing of the auxiliary intake valve 10. In other words, even after natural suction from the auxiliary passage 13 ends, supercharging air is further supplied from the supercharging passage 14, and charging efficiency is greatly improved, thereby ensuring a large engine torque. .

On the other hand, in operating ranges other than high speed and high load ranges, the shutter valve 17 is closed and suction is performed only through the supercharging passage 14. At this time, the supercharging intake valve 1
Since the closing timing of combustion chamber 2 is advanced, particularly in low speed and high load ranges, blowback of intake air from the combustion chamber 6 is suppressed, and charging efficiency is improved. Further, in a light load range, particularly in a low rotation and low load range, the closing timing of the supercharging intake valve 12 is advanced, thereby increasing the effective compression ratio and improving ignition performance.

In the above embodiment, the closing timing of the supercharging port 9 is controlled according to the engine speed using the variable mechanism 28 that changes the opening/closing timing of the supercharging intake valve 12. Instead, a timing valve rotationally driven by the crankshaft is provided in the supercharging passage 14 downstream of the turbocharger 19, and an advance mechanism is provided in the power transmission path between the timing valve and the crankshaft. By providing this, the closing timing of the supercharging passage 14, that is, the supercharging engine 9, may be variably controlled. In this case, the supercharging intake valve 12 simply functions as a shutoff valve. An example of the opening/closing timing of the supercharging port and the auxiliary port in this case is shown in FIG. Of course, the present invention can also be applied to other engines such as diesel engines.

(Effects of the Invention) As is clear from the above, the present invention has the following advantages:
While effectively obtaining partial supercharging, it is possible to improve ignition performance and charging efficiency, which are problems at low engine speeds, and ensure smooth engine operation and sufficient engine torque.

[Brief explanation of drawings]

FIG. 1 is an overall system diagram showing one embodiment of the present invention.
FIG. 2 is a graph showing the intake mode depending on the engine operating mode. 3 and 4 are graphs showing the closing timing of the auxiliary intake valve and the supercharging intake valve. 1: Engine body, 6: Combustion chamber, 7: Auxiliary port, 9: Supercharging port, 10: Auxiliary intake valve, 11:
Supercharging intake valve, 13: auxiliary passage, 14: supercharging passage, 17: shutter valve, 19: supercharger, 28: variable mechanism (timing control means).

Claims (1)

[Claims] 1. A supercharging port and an auxiliary port are opened in the combustion chamber of the engine, and a supercharging passage in which a supercharger is disposed is connected to the supercharging port, while the auxiliary port is connected to a supercharging passage in which a supercharger is disposed. An auxiliary passage for natural suction is connected, and passage switching allows suction to be performed only through the supercharging passage when the engine is running at low speeds, and from both the supercharging passage and the auxiliary passage when the engine is at high speeds. means for setting the closing timing of the supercharging port to be earlier when the engine is running at low speeds than when the engine is at high speeds, and setting the closing timing to be later than the closing timing of the auxiliary port when the engine is at high speeds; A supercharged engine comprising a control means, wherein switching between the passage switching means and the timing control means is set to be performed in synchronization with each other.