JP2612686B2 - Engine intake system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a throttle valve is provided in each of a primary intake passage and a secondary intake passage communicating with a cylinder independently of each other when viewed from one cylinder. The present invention relates to an improvement in an intake system of an engine in which a secondary throttle valve is opened following an operation of a primary throttle valve and a shutter valve is provided in a secondary intake passage to open and close according to an engine operating state.

A typical example of an engine having a primary intake passage and a secondary intake passage that communicate with each other independently of one cylinder is a Wankel rotary engine.

In this case, conventionally, a well-known two-stage carburetor is installed in a primary intake passage that communicates with a cylinder on the primary side, and in a secondary intake passage that communicates the secondary side with the same cylinder, and a secondary throttle valve responds to a Venturi negative pressure. Generally, the air is opened and closed by an actuator that changes the air supply. The air-fuel mixture is always supplied from the primary air intake passage at the time of high output by using the secondary air intake passage together. It promotes atomization of qi.

However, in recent years, electronically controlled fuel injection devices have also been employed in rotary engines. In this case, one of the advantages is that a venturi, which is an intake resistance, is not required, and how to open and close the secondary throttle valve is a problem. Become.

To cope with this, a technique disclosed in Japanese Patent Application Laid-Open No. 58-72616 has been proposed. In this technique, a throttle valve is provided in each of a primary intake passage and a secondary intake passage, and a set opening degree of the primary throttle valve is determined. A secondary throttle valve is opened following the primary throttle valve, and a shutter valve is provided upstream of the secondary throttle valve in the secondary intake passage in response to the intake pipe negative pressure and closed at a low load. Is provided with a delay means for slowing down the opening operation.

In the above configuration, a shutter valve is not required for the purpose of simply increasing the output control accuracy under a low load.
Generally, it is a premixed spark ignition engine that controls the output by the intake throttle, so it is obvious that fuel must be supplied to the primary intake passage that is always used, and the original purpose of this prior art is: It is an object of the present invention to obtain a high-speed airflow in an always-used primary intake passage at a low engine speed and atomize supplied fuel.

By the way, the delay means is configured to delay in time, and when the degree of acceleration of the engine matches the delay opening operation of the shutter valve, the delay means operates effectively while obtaining a high-speed airflow in the primary intake passage.

However, with this configuration, when the vehicle is running on an uphill road where the engine speed does not easily increase, the shutter valve is opened during low rotation. When the primary throttle valve has a high opening degree, the secondary throttle valve is also opened in conjunction therewith, so that a high-speed airflow cannot be obtained in the primary intake passage at the time of low engine rotation, so that atomization of fuel cannot be promoted. Accordingly, the properties of the air-fuel mixture are deteriorated, the ignition / combustibility is reduced, and both the acceleration performance and the fuel consumption performance are deteriorated. In addition, there may be a drawback that the delay means deteriorates output responsiveness.

Therefore, this intake device becomes a low-speed intake device when the shutter valve is closed, and becomes a high-speed intake device when the shutter valve is opened, so that the output abruptly changes in the operation state of the output equilibrium point in both operating states. It is considered that the above-described problem can be solved by using a two-stage variable intake device that switches the operation state without performing the operation.

However, if this intake device attempts to do this, the engine operating state at the output equilibrium point where no sudden change in output occurs generally causes a pressure drop in the intake passage downstream of the primary throttle valve and the secondary throttle valve when the shutter valve is closed. Since the rotational speed starts, the operation state in which the shutter valve can be opened without a sudden change in output is shifted to a lower rotational speed as the secondary throttle valve opening is smaller. This goes against the demand for obtaining a high-speed airflow in the primary intake passage at low engine speed.

Therefore, if the shutter valve can be opened at the highest possible rotation speed without the above-mentioned problem, the intake air can be supplied only from the primary intake passage to the highest possible rotation speed, and a high-speed airflow can be obtained. This is advantageous in terms of formation, and can improve engine performance. However, in the case of such a two-stage variable intake device, in order to obtain smooth running characteristics, it is necessary to consider that the valley of the torque curve near the switching point is made as small as possible.

The present invention has been made to effectively cope with the above-mentioned demands.Specifically, when one cylinder is viewed, a throttle valve is provided in each of a primary intake passage and a secondary intake passage that communicate with each other independently of each other. In the intake system for an engine, the secondary throttle valve is opened in accordance with the primary throttle valve in accordance with the primary throttle valve from the set opening degree of the primary throttle valve, and a shutter valve that opens and closes in accordance with an engine operating state is provided in a secondary intake passage. A two-stage variable intake device in which the engine operating state of an output equilibrium point at which the shutter valve can be opened without a sudden change in output is on the high rotation side as much as possible, and in which the torque drop is as small as possible. It is an object of the present invention to obtain a suitable intake device for an engine.

An embodiment in which the present invention is applied to a two-cylinder engine will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a throttle body, and two cylinders 22a and 22b have primary intake ports 23 respectively.
a, 23b and secondary intake ports 24a, 24b are opened, and these are connected by intake pipes (details not shown), and a bifurcated primary intake passage 2 is connected to the primary intake ports 23a, 23b of each cylinder.
And two or branched secondary intake passages 3 to the secondary intake ports 24a and 24b of each cylinder, and form a primary intake passage 2 and a secondary intake passage 3 that communicate with the cylinder independently of each other. doing. 25, 25 are the primary intake ports 23a, 23 of the respective cylinders 22a, 22b.
This is an injector that injects fuel into b.

A primary throttle valve 4 is provided at a portion of the throttle body 1 of the primary intake passage 2, and a secondary throttle valve 5 is provided at the same portion of the secondary intake passage 3.
Is provided. Reference numeral 6 denotes a primary throttle valve lever having a central portion fixed to a primary throttle valve shaft 7, one end of which is linked to the accelerator pedal so that the primary throttle valve 4 opens in response to depression of the accelerator pedal, and the other end has an arc-shaped slit. 8 are provided. A central portion of a secondary throttle valve lever 10 is fixed to the secondary throttle valve shaft 9, one end of the lever is connected to an arc-shaped slit 8 by a rod 11, and the primary throttle valve 4 reaches a set opening. Then, one end of the rod 11 comes into contact with the end of the arc-shaped slit 8, and the secondary throttle valve 5 starts to open. When the primary throttle valve 4 is fully opened, the secondary throttle valve 5 is also fully opened. Reference numeral 12 denotes a primary intake passage 2 downstream of the primary throttle valve 4 and the secondary throttle valve 5.
And the secondary intake passage 3. A shutter valve 13 is provided downstream of the communication passage 12 of the secondary intake passage 3, and a shutter valve opening restriction lever 15 center portion is rotatably attached to the shutter valve shaft 14 with respect to the shutter valve shaft 14. One end of the shutter valve opening restriction lever 15 and the other end of the secondary throttle valve lever 10 are connected by a rod 16 so that the rotation angles of the secondary throttle valve lever 10 and the shutter valve opening restriction lever 15 are the same. Are linked.
The shutter valve shaft 17 has a shutter valve lever 17
Is fixed, and the end of the shutter valve lever 17 is
It is bent to the near side in the figure so as to contact the other end of the shutter valve opening limit lever 15.

According to the above configuration, the secondary throttle valve 5 opens following the primary throttle valve 4 in conjunction with the primary throttle valve 4 from the set opening degree of the primary throttle valve 4, and the primary throttle valve 4 is connected to the primary throttle valve 4 through the secondary throttle valve lever 10. In conjunction with the opening and closing direction of the primary throttle valve 4, the shutter valve 13
Is limited so as to change the opening degree when is opened. That is, as the opening degree of the primary throttle valve 4 increases, the opening degree when the shutter valve 13 is opened increases. In the present embodiment, the opening when the shutter valve 13 is opened is limited, similarly to the opening of the secondary throttle valve 5.

Next, a method of setting an operation state for opening and closing the shutter valve 13 of the intake device of the engine will be described. The engine output shaft is set for each small division opening from the opening at which the secondary throttle valve 5 of the primary throttle valve 4 starts to open. Variable load (dynamometer) directly connected to
, The shaft torque in the entire engine speed range when the shutter valve 13 is fully closed and when the shutter valve 13 is opened to the opening restricted by the shutter valve opening restriction lever 15 is measured. In the case of an engine with a turbocharger, the measurement is performed such that the turbocharger is in a static operation state instead of a transient state.

Based on the measured data, the engine torque is the same as the shaft torque when the shutter valve 13 for each opening of the primary throttle valve 4 is fully opened and when the opening is limited to the opening limited by the shutter valve opening limiting lever 15. To create a curve as shown in FIG.

The operating state in which the shaft torques when the shutter valve 13 is opened and closed is equal is generally a shaft torque curve that is reduced due to an increase in suction resistance caused by supplying intake air only from the primary intake passage 2 when the shutter valve 13 is closed, and a shutter valve. When 13 is opened, it becomes a low-speed airflow and becomes the intersection with the shaft torque curve that is decreasing due to the decrease in the mixture forming ability. Strictly, a change in the dynamic result (pulsation / inertial effect) of the air column vibration due to the opening and closing of the shutter valve 13 and the like are also added. However, the change is inherent in the shape and size of the intake passage. Is also taken into account.

Next, the opening / closing control of the shutter valve 13 will be briefly described. The engine speed for each predetermined opening degree of the primary throttle valve 4 is read from the curve in FIG. 2 and read in advance in a read-only memory of the control unit (computer) 18. (ROM), and inputs a signal from a primary throttle valve opening sensor 19 mounted on the side opposite to the primary throttle valve lever 6 to the control unit 18 during actual engine operation. Then, the engine speed stored in the adjacent predetermined primary throttle valve 4 opening is called, and the engine speed for the intermediate value of the primary throttle valve 4 opening is calculated by interpolation. Alternatively, a function calculation of a curve approximating the curve of FIG. 2 may be used. Then, the engine speed from the signal input to the control unit 18 from the engine speed sensor 20 is compared with the calculated engine speed, and in a higher speed range than the calculated engine speed, the shutter of the shutter valve shaft 14 is closed. The energization and energization of the rotary solenoid 21 directly connected to the end opposite to the valve opening restriction lever 15 urges the shutter valve 13 in the opening direction, and the opening is restricted by the shutterable opening restriction lever 15. Controlled. Although not described later, the secondary throttle valve 5 is biased by a spring (not shown) in the closing direction so as not to be opened by the rotational force of the rotary solenoid 21. That is, the shutter valve opening limit lever 15 connected by the rod 16 is not pushed or moved by the rotational force of the rotary solenoid 21. On the other hand, in the rotation speed range lower than the calculated engine rotation speed, the rotary valve 21 is not energized and the shutter valve 13 is fully opened. As described above, the rotation angle control of the rotary solenoid 21 is not required, and only the opening / closing operation is required.

In this manner, the shutter valve 13 is opened in the operating range indicated by the hatched portion in FIG. 2, and closed in the other operating ranges. And
When the shutter valve 13 enters the operating range from the closed operating range to the open operating range, the shutter valve 13 is opened from a fully closed state to a limited opening degree at a boundary curve. In the opposite case, the reverse operation is performed. At this time, since the operating state of the boundary curve is an output equilibrium point where the shaft torques during the opening and closing operations of the shutter valve 13 are equal, a sudden change in output does not occur.

If it is assumed that there is no communication passage 12, when the shutter valve 13 is closed and the shutter valve 13 is opened / closed at a rotational speed at which a pressure drop starts to occur in the primary throttle valve 4 and the intake passage downstream of the shutter valve 13 when the shutter valve 13 is closed. As in the prior art, the smaller the opening degree of the secondary throttle valve 5 is, the lower the rotation speed is, as in the prior art.

However, if the communication passage 12 is provided, the intake air that has passed through the secondary throttle valve 5 when the shutter valve 13 is closed flows from the communication passage 12 into the primary intake passage 2 so as to compensate for the amount reduced by the primary throttle valve 4, When the valve 13 is opened, the intake air that has passed through the secondary throttle valve 5 is supplied from the secondary intake passage 3. Therefore, when the shutter valve 13 is closed, the intake resistance mainly due to the intake ports 23 a and 23 b of the primary intake passage 2 starts to increase. There are several engine speeds where the shaft torques when the shutter valve 13 is opened and closed are equal, and as shown in FIG. 2, the smaller the opening degree of the secondary throttle valve 5 is, the higher the rotation speed is. ing.

Considering the case where the mechanism for restricting the opening degree of the shutter valve 13 is not fully provided and only the full opening is performed, when the secondary throttle valve 5 is partially opened when the shutter valve 13 is opened, the primary throttle valve 4 is opened more than that. Therefore, the intake air flows in the reverse direction from the primary intake passage 2 having a small throttle resistance to the secondary intake passage 3 having a large throttle resistance through the communication passage 12, and the primary intake passage 2 has a small throttle resistance. Since the decrease in the flow velocity increases and the air-fuel mixture forming ability decreases, the operating state when the shutter valve 13 is closed, which balances the output, is where the suction resistance increases and the torque drops, so the shutter valve 13 is opened. The drop in the torque curve near the operating state of the output equilibrium point is large. Therefore, the opening of the shutter valve 13 is limited to suppress the inflow in the reverse direction, and resistance is given to the shutter valve 13. Therefore, the drop of the torque curve near the engine rotations at the output equilibrium point at the time of opening and closing is reduced.

As described above, setting the engine speed at which the shutter valve 3 opens and closes in accordance with the opening degree of the throttle valve, when applied to an automobile engine, is almost impossible in normal running because the throttle operation is almost performed. The significance is great.

The shutter valve opening limit lever 15 may be moved directly from the primary throttle valve lever 6 without passing through the secondary throttle valve lever 10.

If necessary, the limit opening of the shutter valve 13 does not have to be the same as the opening of the secondary throttle valve 5.

As described above, according to the present invention, when one cylinder is viewed, a throttle valve is provided in each of the primary intake passage and the secondary intake passage communicating with the cylinder independently of each other, and the set opening degree of the primary throttle valve is provided. In the intake system for an engine, the secondary throttle valve is opened following the primary throttle valve in conjunction with the primary throttle valve, and the secondary intake passage is provided with a shutter valve that opens and closes according to the engine operating state. A communication path communicating downstream is provided, and the shutter valve is provided downstream of the communication, and cooperates with the primary throttle valve to coincide with the opening / closing direction of the primary throttle valve to change the opening when the shutter valve is opened. The engine operating state in which the shutter valve can be opened without a sudden change in output is as high as possible, and a torque car near the operating state is provided. Can be obtained slump is as small as possible two-stage variable intake apparatus, the intake system of the preferred engine and.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part showing an embodiment of an intake device for an engine of the present invention, and FIG. 2 shows an operating state in which an opening / closing operation area of a shutter bubble and an opening / closing operation of the engine with an intake device of the embodiment of the present invention. It is a graph. 1 ... Throttle body, 2 ... Primary intake passage, 3 ...
Secondary intake passage, 4 ... Primary throttle valve, 5 ... Secondary throttle valve,
6 Primary throttle valve lever, 7 Primary throttle valve shaft, 8
Arc-shaped slit, 9 secondary throttle valve shaft, 10 secondary throttle valve lever, 11 rod, 12 communication passage, 13 shutter valve, 14 shutter valve shaft, 15 shutter Valve opening limit lever, 16 Rod, 17 Shutter valve lever, 18 Control unit, 19 Primary throttle valve opening sensor, 20 Engine speed sensor, 21
… Rotary solenoid, 22a, 22b …… Cylinder, 23a, 23b…
Primary intake port, 24a, 24b ... Secondary intake port, 25 ...
Injector

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location F02M 35/108 F02M 35/10 301B

Claims (1)

(57) [Claims] When viewed from one cylinder, a throttle valve is provided in each of a primary intake passage and a secondary intake passage communicating with the cylinder independently of each other, and the throttle valve is interlocked with the primary throttle valve based on a set opening degree of the primary throttle valve. Subsequently, the secondary throttle valve is opened, and a shutter valve that opens and closes in accordance with an engine operating state is provided in the secondary intake passage. In an intake device for an engine, a communication passage communicating each intake passage downstream of each throttle valve is provided. A shutter valve is provided downstream of the communication path, and a mechanism is provided for interlocking with a primary throttle valve and for restricting the opening degree of the shutter valve to be changed in accordance with the opening / closing direction of the primary throttle valve. An intake device for an engine.