JPS58117318A - Suction device for engine - Google Patents

Abstract

PURPOSE:To prevent a crosscurrent to atmospheric air by providing the downstream side of the control valve of a suction reflux path with an expansion chamber and temporarily collecting a suction flowed back from a cylinder into the expansion chamber. CONSTITUTION:When the engine is operated under high load, the cylinder C is supplied with suction air through a suction path 10 and a suction port 1 because an opening and closing valve 15 is closed. When the engine is operated under low load, the opening and clsoing valve 15 is opened, and a cam 6 opens and closes a suction reflux valve 9 while delaying only by predetermined phase from a suction valve 7. The suction reflux valve 9 is opened for a fixed time even in the compression process of the engine E. One part of suction air in the cylinder C is flowed back into the suction path 10 through a suction reflux port 3 and the suction reflux path 14 at the same time. Most of suction air flowed back are introduced into the expansion chamber 16, and expanded temporarily and collected, thus resulting in no crosscurrent to atmospheric air.

Description

[Detailed description of the invention] The present invention relates to an engine intake device.

In an Otsuto cycle engine, it is not possible to extract all of the heat energy generated in the engine as shaft output, and a portion of it is lost as various losses such as heat loss and mechanical loss, which becomes an obstacle to improving fuel efficiency. ing. One of these mechanical losses is the pump loss during the suction and exhaust strokes, and this pump loss is larger at low loads than at high loads. This is hindering improvements in fuel efficiency. On the other hand, it is known that fuel efficiency improves when a pump with a small stroke volume is mounted on the same vehicle, but this means that the engine operates at a relatively high load, which reduces pump loss. This is thought to be one of the major reasons. Therefore,
If the engine performs the same function as a small stroke volume engine only at low loads, pump loss at low loads can be reduced and fuel efficiency can be improved without compromising the engine's required characteristics at high output. It is thought that it can be done.

In other words, in order to reduce the pump loss at low loads, it is necessary to reduce the throttling loss due to the increase in suction negative pressure due to the opening of the small throttle valve during the suction stroke and the compression loss during the compression stroke. good. As a means of this failure, for example, Tokukaisho! As described in No. 2-/39g/9, in addition to the normal intake passage, an auxiliary intake passage is provided to allow part of the intake air to leak during the compression stroke, and an auxiliary intake valve is arranged in this auxiliary intake passage. However, there is a known device in which the closing timing of this auxiliary intake valve is set to be later than the closing timing of the normal intake valve, and the auxiliary intake valve is opened and closed only when the engine is at low load, that is, at partial load. ing. That is, the intake device of the engine is connected to an intake passage that supplies intake air from the atmosphere into the cylinder during the intake stroke of the engine, and the middle of the intake passage communicates with the cylinder, so that the intake air inside the cylinder during the compression stroke of the engine is connected. The intake air recirculation passage is composed of an intake recirculation passage that recirculates a part of the intake air to the intake passage, and a control valve that opens and closes this intake air recirculation passage. The amount of air filling is controlled.

The intake system of this engine reduces pump loss at low loads, and from this point of view it is thought that fuel efficiency will be greatly improved. There is a particular problem in that some of the K flows back into the atmosphere together with the fuel when it is exhausted from the cylinder during the compression stroke, and this can increase intake noise and pose a risk of fire due to fuel release. there were.

SUMMARY OF THE INVENTION Therefore, the present invention provides an engine intake system with reduced pumping loss of the type described above, which has a structure that prevents recirculated intake air from inside the cylinder during the compression stroke from flowing back into the atmosphere.
The purpose of this invention is to provide an intake device for the following.

The present invention provides an intake passage that supplies intake air from the atmosphere into the cylinder during the intake stroke of the engine, and a midway of the intake passage and the cylinder, so that the intake air in the cylinder is supplied during the compression stroke of the engine. It has an intake air recirculation passage that partially returns to the intake passage, and a control valve that opens and closes the intake air recirculation passage, and controls the opening and closing of the control valve to adjust the amount of intake air recirculation. The intake system for an engine is characterized in that an expansion chamber is provided in the intake air recirculation passage downstream of the control valve in the recirculation direction.

According to the engine intake system of the present invention, since the expansion chamber is provided on the downstream side of the control valve E in the intake air recirculation passage, the intake air recirculated from inside the cylinder is temporarily stored in this expansion chamber, thereby Backflow to the atmosphere is prevented, thereby substantially eliminating the increase in intake noise and the risk of fire caused by venting intake air to the atmosphere.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An engine intake system according to a preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing an intake system of an engine according to an embodiment of the present invention. In this figure, the symbol E designates an engine, and this engine E has a cylinder C as a cylinder and a cylinder C as a cylinder. It has a fitted piston P. In addition to the normal intake port 1 and exhaust port 2, an intake recirculation port 3, which is a third port, is provided at the top of the cylinder C. Intake port 1, exhaust port 2
In the intake recirculation port 3, an intake valve 7, an exhaust valve 8, and an intake recirculation valve 9 whose opening and closing are controlled by first, third cams 4.5 and 6, respectively, are arranged.

Inhalation? - An intake passage 10 is connected to the port 1, and an exhaust passage 11 is connected to the exhaust port 2. A carburetor 12 is provided in the intake passage 10. On the downstream side of the carburetor 12, there is a carburetor 12 that is fully open during normal operation.
A valve 13 is provided that closes the intake passage 10 during startup and deceleration. The downstream side of the valve 13 of the intake passage 10 and the intake recirculation port 3 are communicated by an intake recirculation passage 14 that recirculates the intake air from the cylinder C to the intake passage 10 via the intake recirculation port 3 during the compression stroke. ing. An on-off valve 15 interposed in the intake air recirculation passage 14 is interposed in conjunction with an accelerator pedal (not shown). This on-off valve 15 is
It is configured to be fully closed at full load, and open at low load with an opening degree commensurate with the load. The intake air recirculation passage 14 is located downstream of the on-off valve 15 of the intake air recirculation passage 14 in the intake air recirculation direction.
An expansion chamber 16 is provided for storing the intake air that is recirculated. Note that it is desirable that the intake recirculation passage portion 14a connecting the expansion chamber 16 and the intake passage 10 be made somewhat thinner than the other portions to have a slight throttling effect.

The on-off valve 15 and the intake air recirculation valve 9 constitute a control valve that adjusts the intake air recirculation amount.

Next, the operation of the engine intake system with the structure explained above is as follows.
This will be explained with reference to the valve operation timing chart shown in FIG.

First, when operating under high load when the accelerator pedal is depressed, the on-off valve 15 is closed, so intake air is supplied to the cylinder C via the intake passage 10 and the intake port 1, and from the cylinder C. Since the intake air is not recirculated through the intake recirculation port 3, the engine E
is operated under the same conditions as a normal engine.

Next, explaining the case of low-load operation, the on-off valve 15 is opened in conjunction with the release of the accelerator pedal. The cam 6 closes the intake recirculation valve 9 to the second position.
As shown in the figure, the intake valve 7 is configured to open and close with a certain phase delay, that is, the intake recirculation valve 9
is opened for a certain period of time during the compression stroke of the engine E, and during this period, the intake recirculation port 3 and the intake recirculation passage 14 are opened.
A part of the intake air in the cylinder C is recirculated toward the intake passage 10 through the cylinder C. This recirculation amount is substantially adjusted by the relationship between the opening degree of the on-off valve 15 and the closing timing of the intake recirculation valve 9, and is set to increase as the load decreases. Most of the recirculated intake air is
Since the air is introduced into the expansion chamber 16, temporarily expanded and stored there, the air recirculated through the port 3 and the intake air recirculation passage 14 in the compression stroke of the M/S/E as described above is at atmospheric pressure. There is no backflow.

In the above embodiment, the opening/closing operation of the intake recirculation valve 9 is fixed, and the intake recirculation amount is controlled by adjusting the opening of the opening/closing valve 15.
The above-mentioned control valve can also be omitted by making the closing timing of the intake air recirculation valve 9 variable and controlling the intake air recirculation amount. In this case, for example, a cam whose cam profile changes in the cam shaft direction is used as the cam 6, and by moving the cam in the cam shaft direction according to the work/no/load, the opening performance of the intake recirculation valve 9 can be adjusted. need to change.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an engine intake system according to an embodiment of the present invention, and FIG. 1 is an opening/closing timing chart showing the opening/closing characteristics of the valves of the intake system shown in FIG. E...Engine, C...Cylinder as a cylinder, P
... Piston, 1... Intake port, 2... Exhaust port, 3... Intake recirculation port, 7... Intake valve,
8...Exhaust valve, 9...Intake recirculation valve, 10.
...Intake passage, 11...Exhaust passage, 14...Intake recirculation passage, 15...Opening/closing valve, 16...Expansion chamber. Percentage Applicant Toyo Kogyo Co., Ltd. Figure 1 Figure 2 Crank Rotation Town

Claims (1)

[Claims] An intake passage that supplies intake air from the atmosphere into the cylinder during the intake stroke of the engine, and a part of the intake passage communicates with the front cylinder, so that a part of the intake air in the cylinder is supplied during the compression stroke of the engine. The intake air recirculation passage includes an intake air recirculation passage that recirculates the air to the intake passage, and a control valve that opens and closes the intake air recirculation passage, and controls the filling amount of intake air by controlling the opening and closing of the control valve to adjust the intake air recirculation density. An intake system for an engine as described above, characterized in that an expansion chamber is provided in the intake air recirculation passage on the downstream side of the side-inverted J valve in the intake air recirculation direction.