JPH0672537B2 - Engine intake system - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an intake device that performs intake using pressure waves generated in an intake passage.

(Prior Art) Conventionally, an engine has been proposed in which dynamic effects of intake air, such as intake inertia and resonance effect, are utilized to improve the charging efficiency and thereby secure a high output.

However, when the effect of the pressure wave of the intake air is used to improve the charging efficiency, there are the following problems. When the engine speed decreases, the lowering speed of the piston decreases, and thus the negative pressure wave generated decreases, and the effect of improving the filling rate also decreases. In addition, the propagation of the pressure wave occurs at a constant velocity called sonic velocity, whereas the timing imitation, which is desired to have the effect of pushing the intake air by the pressure wave, changes according to the engine speed, so the pressure wave is generated in a wide rotational speed range. It is difficult to obtain the effect of improving the filling efficiency.

In view of such circumstances, JP-A-55-107018 discloses that
A valve plate provided in an intake passage upstream of the intake valve and in an intake passage communicating with the cylinder and the intake passage, and rotating at the same speed as or half the rotational speed of the crankshaft. And a charge control valve having a control valve for controlling the communication between the cylinder and the charge reservoir according to the rotation speed of the crankshaft by the control valve, thereby increasing the filling rate by the pressure wave of intake air in a wide range of rotation speeds. An engine intake structure adapted to be obtained is disclosed.

(Problems to be Solved by the Invention) In the above-mentioned Japanese Patent Laid-Open No. 55-107018, an intake negative pressure wave generated on the downstream side in a charge reservoir having a certain volume provided in the intake passage is inverted into a positive pressure wave. The inversion positive pressure wave is used to improve the filling efficiency. However, in the type in which the volume is provided in the intake passage to form the reversing portion, the intake device becomes large, and a layout problem occurs in the engine room with a limited space. Further, it is possible to incorporate the supercharger into the intake device that utilizes such pressure oscillation of the intake air, but in this case, the reversing volume section must be provided separately from the supercharger. However, the above layout problem becomes more serious.

(Means for Solving the Problems) The present invention is configured to solve the above problems, and an intake device of the present invention includes an intake port opened and closed in synchronization with rotation of an engine, A control valve which is provided in the intake passage upstream of the intake port and controls the intake passage to be opened after the opening timing of the intake port and after the intake top dead center to delay the intake start timing, at least at low rotation and high load. And a positive displacement supercharger provided in the intake passage upstream of the control valve. The supercharger has a timing synchronized with the intake start timing so that the pressure wave generated in the intake system at the start of intake and the pressure wave generated in the intake system due to the operation of the supercharger interfere with each other in a reversed phase relationship. It can be operated with.

The intake system of the present invention includes a positive displacement supercharger upstream of the control valve. The supercharger of the present invention is a positive displacement supercharger, and the intake air discharged into the intake passage due to its operation is accompanied by a constant pressure fluctuation. As the supercharger applicable to the present invention, various positive displacement superchargers such as a vane type, a roots type and a piston type can be mentioned. Further, the control valve of the present invention is designed to be opened later than the intake top dead center, that is, TDC, at least during low rotation and high load operation, and the control valve is opened in the intake system. When the intake is started, a large negative pressure wave is generated, and this negative pressure wave propagates through the intake passage to the upstream side. According to the present invention, due to the operation of the supercharger, the pressure wave generated in the intake system and the pressure wave generated when the control valve is opened interfere with each other in a mutually reversed phase relationship in the intake passage. The operation of the feeder determines the timing. Due to this interference, the negative pressure wave generated when the control valve is opened is inverted and becomes a positive pressure wave, which is introduced into the combustion chamber at the end of the intake stroke.

In this case, the opening timing of the control valve should be changed stepwise or continuously according to changes in engine speed and load even if there is a certain deviation from the opening timing of the intake valve. Is also good.

In a preferred aspect of the present invention, the delay control of the intake start timing by the control valve is released during low load and high rotation. This releasing means sets, for example, the opening timing of the control valve to be equal to or more than the intake valve,
When the load is low and the rotation is high, the advance mechanism may be used to match the valve opening timing of the control valve with the intake valve. Further, a bypass passage for bypassing the control valve provided for each cylinder may be provided, a bypass valve for opening and closing the bypass passage may be provided, and the bypass valve may be opened during low load and high rotation. Further, a bypass passage is provided to connect the independent intake passages for the respective cylinders on the downstream side of the control valve to each other, and a bypass valve is installed in the passage, and this valve is opened at low load and high rotation to intake the other cylinders. The intake air may be introduced through the passage.

(Effect of the present invention) According to the present invention, the pressure wave generated in the intake passage due to the operation of the supercharger and the pressure wave generated in the intake passage due to the opening operation of the control valve are mutually in phase. They are trying to interfere with each other in a reversed relationship. As a result, the negative pressure wave generated when the control valve is opened is reversed and becomes a reflected positive pressure wave, which returns to the combustion chamber and brings about the effect of pushing the intake air. Thereby, a high filling rate can be secured and the output can be improved. Therefore, according to the present invention, it is not necessary to provide a special volume portion for inverting the negative pressure wave in the intake system, and the device can be made compact, which is extremely advantageous in layout.

In addition, the engine speed (hereinafter referred to as the tuning speed) that generally provides the effect of increasing the filling rate due to the pressure wave generated in the intake system
Is represented by the following relational expression.

Here, N: tuning rotation speed (rpm), θ _e : effective valve opening period (d
eg), ν: Natural frequency of intake system during intake valve opening period (H
z).

The effective valve opening period does not mean the valve opening period of the intake valve, but is a period during which intake air is actually introduced into the cylinder.

In the present invention, controlling by the control valve so as to delay the intake introduction start timing means performing control for changing the effective valve opening period θ _e in the equation (1). As a result, according to the control of the present invention, it is possible to obtain a tuned rotation speed in a wide rotation speed range, and it is possible to obtain a desired effect of increasing the charging efficiency by the pressure wave in each of different rotation ranges. Further, in a preferred aspect of the present invention, at the time of high rotation, the delay control by the control valve is controlled so as to cancel the delay control by the control valve in view of the fact that the delay control is rather harmful as a result of increasing the passage resistance. This extends the effective valve opening period, that is, the above (1)
In the equation, θ _e becomes large, the passage resistance is reduced, a large amount of intake air can be introduced, and the intake system is designed to have a natural frequency such that the rotational speed of the pressure wave can be tuned in such an operating region. With the configuration, the dynamic effect of intake air can be obtained together, and the charging efficiency can be further improved.

Further, since pumping loss at low load increases and fuel consumption is adversely affected, it is desirable to cancel the delay control in the same manner. By controlling the control valve in this manner, it is possible to secure a sufficient intake air amount at the time of high rotation, and it is also possible to prevent a decrease in fuel consumption at the time of low load.

(Description of Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1 and FIG. 2, the engine 1 of this example is
It is a four-cylinder engine, and four cylinder bores 3 are formed in the cylinder block 2, and a piston 4 is reciprocally arranged in each cylinder bore 3. A cylinder head 5 is coupled above the cylinder block 2, and a space formed by a space above the piston of the cylinder bore 3 and a lower recess of the cylinder head 5 constitutes a combustion chamber 6. An intake port 7 and an exhaust port 8 are opened in the combustion chamber 6, and an intake passage 9 and an exhaust passage 10 are formed in the cylinder head 5 so as to communicate with the intake port 7 and the exhaust port 8. An intake valve 11 is associated with the intake port 7, and an exhaust valve 12 is associated with the exhaust port 8. Further, a spark plug 12a is arranged on the cylinder head 5 so that its tip portion projects into the combustion chamber. A manifold is connected to the intake passage 9 of each cylinder, a fuel injection nozzle 12b is attached near this connection portion, and each intake passage 9 is connected.
Merging upstream, a main intake passage 13 is formed and extends further upstream. An air cleaner 14 is provided at the upstream end of the main intake passage 13.
Is installed, and an air flow meter 15 for measuring the intake air flow rate is provided downstream of the air cleaner 14.

The intake system of the present example includes a positive displacement supercharger 16 on the downstream side of the air flow meter 15 and connects the upstream and downstream of the supercharger 16. It has a relief passage 33. A relief valve 34 for adjusting the relief amount of the supercharger is provided in this relief passage. A pulley 35 is attached to a drive shaft 16a for driving the air pump of the supercharger 16, and this pulley 35 is driven by a drive pulley 25 attached to the end of the crankshaft 24 via a timing belt 26. It is designed to be driven. Further, a throttle valve 17 is arranged in the main intake passage 13, and a cylindrical rotary valve as shown in FIG. 3 is provided at a branch portion downstream of the throttle valve.
18 is rotatably arranged. The intake passages 9 to the respective cylinders downstream of the branch portion are communicated with each other by a bypass passage 19, and a bypass valve 20 is attached to a connection portion between the bypass passage 19 and each intake passage 9. The upstream side of the bypass passage 19 is connected between the branch portion of the main intake passage 13 and the throttle valve 17. An opening 21 that communicates with the intake passage 9 of each cylinder at a predetermined rotation position is provided on the peripheral wall of the rotary valve 18 for each cylinder.
In this example, since ignition is performed in the order of 1-3-4-2,
In order to avoid mutual interference of intake air, the opening positions for the first and fourth cylinders and the opening positions for the second and third cylinders are formed in the same orientation.
As shown in FIG. 1, the rotary shaft 18a of the rotary valve 18
Are connected to a pulley 23 via an advance mechanism 22. The pulley 23 is connected to the drive pulley 25 of the crankshaft 24 via a timing belt 26. In this example, the pulley 23 and the pulley 25 have the same diameter, so that they rotate at the same speed. The advance mechanism 22 includes a helical gear 27 attached to the end of the rotary shaft 23a of the pulley 23.
A helical gear 28 that is attached to the end of the rotary shaft 18a of the rotary valve 18 and that faces the helical gear 27 on the pulley 23 side; and an adjustment piece 29 that meshes with both helical gears 27, 28. ing. The adjusting piece 29 is a helical gear 27 and
The meshing position with 28 can be changed in the rotation axis direction of the rotary valve 18, and when the adjusting piece 29 moves in the axial direction and the meshing position changes, the relative rotation position with the helical gears 27, 28 changes. By this, the amount of advance angle is changed. An actuator 30 is provided to adjust the axial position of the adjustment piece 29, and the actuator is preferably operated by a command signal from a control unit 31 including a microcomputer. There is. In this example, a signal indicating the engine speed is input to the control unit 31, and the control unit 31 determines the advance amount according to the speed signal, and advances it via the actuator 30. Drives the angular mechanism 22. Further, the control unit 31 is also adapted to receive an engine load signal, and the control unit 31 controls the actuator 20a of the bypass valve 20 to bypass in a predetermined operating region in accordance with the rotation speed and the load value. A command signal is output to open the valve 20.

In the above structure, in this example, the rotary valve 18 rotates at the same speed as the crankshaft 24 by transmitting the engine power from the pulley 25 to the pulley 23 via the timing belt 26. Further, since the timing belt 26 is wound around the drive pulley 35 of the supercharger 16, the drive shaft of the air pump is driven by the timing belt 26 like the rotary valve. Therefore, when the opening 21 of the rotary valve 18 communicates with the intake passage 9 of each cylinder, that is, the opening period of the rotary valve 18, the intake valve 11 of each cylinder is opened.
The operation of the supercharger occurs in synchronization with the valve opening period of. In this example, intake air is actually introduced into the combustion chamber 6 during the period when the intake valve 11 is open and the rotary valve 18 is open. Therefore, this period is the effective valve opening period. Referring to FIG. 4 together, the opening period of the rotary valve 18 is adapted to be changed according to the engine speed, and as the speed increases, the rotary valve 18 is changed as shown by the broken line in the figure. The valve opening timing of is set so as to approach the valve opening timing of the intake valve 11. On the other hand, when the engine speed is low, the valve opening timing of the rotary valve 18 is shifted to the delay side by the operation of the advance mechanism 22 as shown by the solid line in the figure. The intake air is actually introduced into the combustion chamber 6 when the rotary valve 18 is opened, but at the time of opening this valve, a negative pressure wave of the intake air is generated on the downstream side of the rotary valve 18, and this negative pressure wave is Propagate upstream through the intake passage 13. On the other hand, in the supercharger 16, the operation thereof causes the intake air to be discharged into the intake passage 13 with a constant pressure fluctuation.
A pressure wave resulting from the operation of the supercharger 16 is generated toward the downstream side of the intake passage 13. In the intake device of this example, the pressure wave based on the opening operation of the rotary valve 18 and the pressure wave based on the operation of the supercharger 16 are both generated in a certain relationship with the rotation of the crankshaft. The intake system is configured so that the two pressure waves interfere with each other in a mutually reversed phase relationship in the intake passage. As a result, the negative pressure wave generated due to the opening operation of the rotary valve 18 is inverted and becomes a positive pressure wave, which propagates in the intake passage 13 to the downstream side and finally reaches the combustion chamber 6.
To reach.

In this example, the intake system is configured so that the positive pressure wave reaches the combustion chamber 6 at the end of the intake stroke, and thus the intake pressure pushing effect of the positive pressure wave is utilized to achieve high intake efficiency. Trying to get. Then, in consideration of the fact that the larger the amplitude of the negative pressure wave generated when the rotary valve 18 is opened, the larger the reversal positive pressure wave is generated, and as a result, the larger effect of increasing the charging efficiency is obtained, the piston speed is slower in the present example, and therefore, the resulting The configuration is such that, at the time of low rotation in which the negative pressure wave tends to be small, the valve opening timing of the rotary valve 18 is delayed compared with the time of high rotation, and a larger negative pressure wave is formed. Further, the engine speed at which the effect of increasing the filling rate by the pressure wave is obtained, that is, the tuning speed N (rpm)
Is expressed as N = θ _e · ν / 6 as a function of the effective valve opening period θ _e (deg) and the natural frequency ν (Hz) of the intake system. In the device of this example, the advance mechanism 22 is Since the effective valve opening period θ _e is changed according to the rotation speed change, the tuning rotation speed can be obtained over a wide rotation speed range, and as a result, a wide rotation speed range from low rotation speed to middle rotation speed can be obtained. Thus, the effect of increasing the filling rate can be obtained.

In the high engine speed region, when the control for shifting the rotary valve to the delay side is performed as described above, the passage resistance increases, which may adversely affect the securing of the high filling amount. Therefore, in this example, when the rotation speed is high, the actuator 20a is operated to open the bypass valve 20,
The intake air is also introduced from the bypass passage 19.
As a result, it is possible to solve the problem that intake air shortage occurs at high rotation speeds. Further, when the control is performed such that the opening timing of the rotary valve 18 is delayed at a relatively low engine speed and a low load, the pumping loss increases, and the deterioration of fuel efficiency becomes remarkable. Similarly, the bypass valve 20 is opened, and the intake air is also introduced from the bypass passage 19 to substantially cancel the delay control of the rotary valve 18.

As described above, in the structure of the present example, the supercharger can be provided with the function of reversing the intake negative pressure wave generated at the opening timing of the rotary valve 18 without impairing its function. It is not necessary to provide a special volume part of, and the intake system can be configured compactly.

In addition, FIG. 5 shows another embodiment of the present invention. In this embodiment, between the drive shaft of the air pump and the drive pulley 35, the same advance mechanism as the rotary valve 18 in the preceding example is provided. The rotary valve controls the intake timing of the air pump.
A discharge timing variable mechanism 36 for precisely matching the valve opening timing of 18 is provided. In addition, the intake passage 13
Downstream of the supercharger 16 of the
Forming a 6 '. This makes it possible to adjust the negative pressure wave generated by the valve opening operation of the rotary valve and the pressure wave caused by the supercharger operation so that they interfere with each other in an exactly reversed relationship, and also effectively reverse the negative pressure wave. A phenomenon can occur.

In addition, in the above embodiments, the example in which the present invention is applied to the reciprocating engine has been described, but the present invention can also be applied to the rotary piston engine in the same manner.

[Brief description of drawings]

1 is a schematic view of an engine according to an embodiment of the present invention, FIG. 2 is a partial sectional view of the engine of FIG. 1, FIG. 3 is a perspective view of a rotary valve, and FIG. FIG. 5 is a graph showing the valve opening timing of the valve, and FIG. 5 is a schematic view of an engine according to another embodiment of the present invention. 1 ... Engine, 2 ... Cylinder block, 3 ... Cylinder bore, 4 ... Piston, 5 ... Cylinder head, 6 ... Combustion chamber, 9 ... Intake passage, 10 ... Exhaust passage, 13 ... Main intake Passage, 14 ... Air cleaner, 15 ... Air flow meter, 16 ... Supercharger, 17 ... Throttle valve, 18 ... Rotary valve, 19 ... Bypass passage, 20 ... Bypass valve, 22 ... Advance mechanism , 31 …… Control unit.

Front page continuation (72) Inventor Junzo Sasaki No. 3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Inventor Kazunori Tominaga No. 3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd.

Claims (1)

[Claims] 1. An intake port that is opened and closed in synchronization with the rotation of an engine, and an intake port that is provided in an intake passage upstream of the intake port and that opens the intake passage after the opening timing of the intake port at least at low rotation and high load. A control valve that opens after intake top dead center and delays the intake start timing, and a positive displacement supercharger that is provided in the intake passage upstream of the control valve. In order that the pressure wave generated in the intake system and the pressure wave generated in the intake system due to the operation of the supercharger interfere with each other in a reversed phase relationship, it was possible to operate at a timing synchronized with the intake start timing. Characteristic engine intake device.