JPS6282228A - Suction device for multicylinder engine - Google Patents

Abstract

PURPOSE:To improve the turnover effect of a pressure wave and make it into high output, by installing an on-off valve, which is synchronized with an engine and variable in its on-off timing, in an independent suction passage, and setting the upstream of this on-off valve converge on at each cylinder in the relation that phase of each cylinder is reversed. CONSTITUTION:A rotary on-off valve 18 is installed in a suction passage independent from each cylinder, driven by a crankshaft 24 via a phase changing device 29, and synchronized with an engine speed, while its on-off timing is controlled by a control unit 31 according to engine load and speed. The suction passage at the upstream of the on-off valve 18 is joined with each suction passage 9 at every cylinder in the relation that phase of each cylinder is reverse. With this constitution, a pressure wave of suction pulsation at the time of a hole 21 of the on-off valve 18 being opened receives pressure of the suction passage of other cylinders when it turns over at this converging part, thus a sufficient turnover effect is secured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in an intake device that performs intake using pressure waves generated within an intake passage.

(Prior Art) Engines have been proposed that utilize dynamic effects of intake air, such as intake inertia and resonance effects, to increase charging efficiency and thereby ensure high output.

However, when attempting to improve filling efficiency by utilizing the effect of pressure waves of intake air, the following problems arise. When the engine speed decreases, the piston machining speed decreases, and therefore the generated negative pressure wave decreases, and the resulting filling rate improvement effect also decreases. In addition, while pressure waves propagate at a constant speed, the speed of sound, the desired timing for the pressure wave to push the intake air changes depending on the engine rotational speed. It is difficult to obtain the effect of improving filling efficiency.

In view of these circumstances, Japanese Patent Application Laid-Open No. 55-107018
The publication describes an air supply section provided in the intake passage upstream of the intake valve, and an air supply section provided in the intake passage communicating the cylinder and the air supply section, and at a speed equal to or half the rotational speed of the crankshaft. The control valve is equipped with an air supply control valve having a rotating valve plate, and the control valve controls communication between the cylinder and the air supply section according to the rotational speed of the crankshaft. An intake structure for an engine that achieves the effect of increasing the filling rate is disclosed.

(Problems to be Solved by the Invention) In the above-mentioned Japanese Patent Application Laid-Open No. 55-107018, an intake negative pressure wave generated on the downstream side of an air supply section provided in the middle of an intake passage and having a constant volume is reversed into a positive pressure wave. The filling efficiency is improved by this inverted positive pressure wave. However, in such a type in which a volume portion is provided in the intake passage to constitute an inverted portion, the intake device becomes large, and problems arise in terms of layout in an engine room with limited space.

In addition, the negative pressure waves generated in the intake system propagate upstream through the intake passage, are reversed at the air supply section, and the reflected waves propagate downstream and are guided into the combustion chamber. propagate to. This adversely affects the operation of the air flow meter disposed upstream of the air supply section, causing measurement errors.

(Means for solving the above problems) The present invention is configured to solve the above problems, and the intake device of the present invention includes an intake port that opens and closes in synchronization with the rotation of the engine, and an intake port that opens and closes in synchronization with engine rotation. a control valve that is provided in an intake passage upstream of the intake boat and controls the intake passage to open after the intake port opening timing and after suction top dead center to delay the intake start timing, at least under low rotational load; ,
an inversion section provided in the intake passage upstream of the control valve and for inverting an intake negative pressure wave generated downstream of the control valve when the control valve is opened; It is characterized in that the intake passages are connected so that the intake negative pressure waves whose phases are opposite to each other interfere with each other on the side.

The control valve of the present invention opens later than the intake top dead center, that is, TDC, at least during low-speed, high-load operation, thereby generating a large pressure wave and providing a pushing effect on intake air at the end of the intake stroke. It has become. In this case, the opening timing of the control valve may be constant, or may be changed stepwise or continuously in accordance with changes in engine speed and load.

The intake device of the present invention includes, upstream of the control valve, an inversion section that inverts a negative pressure wave of intake air generated downstream when the control valve is opened. This inversion section connects the intake pipes of the cylinders, in which the phases of the generated negative pressure waves are shifted by half a wavelength, to face each other on the upstream side of the control valve, so that the phase relationship of the intake negative pressure waves is reversed. configured to interfere. In the present invention, preferably, the connection portion between the intake pipes is expanded to have a constant volume. In addition, on the upstream side of this reversal part, there is a certain volume that is directly connected to the intake passage or branched from the intake passage to prevent pressure waves from propagating upstream or to enhance the reversal effect. It is desirable to provide a reflective section. In a preferred embodiment of the present invention, the delay control of the intake start timing by the control valve is canceled when the load is low and the engine speed is high. This release means, for example, sets the valve opening period of the control valve to be longer than the intake valve, and uses an advance mechanism to adjust the opening period of the control valve to the intake valve during low load and high rotation. You can configure it to match. Also,
A bypass passage that bypasses a control valve provided for each cylinder may be provided, and a bypass valve that opens and closes this bypass passage may be provided, and the bypass valve may be opened during low load and high rotation. Furthermore, a bypass passage is provided that communicates the independent intake passages for each cylinder on the downstream side of the control valve, and a bypass valve is installed in the passage, and this valve is opened at low loads and high rotations to allow intake air from other cylinders to flow through the intake passages. Intake air may be introduced through the passage.

(Effects of the Present Invention) According to the present invention, the inversion section that inverts the negative pressure waves generated in the intake system is configured by connecting the intake passages so that the intake negative pressure waves interfere with each other in a reversed phase relationship. The structure of the present invention allows the intake system to be made more compact than a structure in which an inversion part is essentially provided with a volume part, and is advantageous in terms of layout. Furthermore, since the inverting section according to the present invention is constructed by interfering negative pressure waves with reversed phases, this interference generates an inverted positive pressure wave, and the negative pressure waves themselves cancel each other out due to the interference. Pressure fluctuations on the side are effectively damped. Therefore, the adverse effect on the metering operation of the air flow meter disposed upstream of the reversing section can be extremely suppressed.

Further, according to the present invention, at least during low rotation and high load operation, the control valve is controlled to open later than suction top dead center, and a large negative pressure wave is generated downstream of the control valve in the intake passage. The pressure wave propagates upstream in the intake passage and is reversed at the reversal section to become a positive pressure wave. This positive pressure wave propagates downstream as a reflected wave and exerts the effect of pushing intake air into the combustion chamber at the end of the intake stroke. Due to this effect, the engine according to the present invention can ensure high charging efficiency, and therefore can improve output.

In general, the engine rotational speed (hereinafter referred to as the tuned rotational speed) at which the effect of increasing the filling rate due to the pressure waves generated in the intake system is obtained is expressed by the following relational expression.

Here, N: tuned rotational speed (rpm), θe: effective valve opening period (deg), and C: natural frequency (Hz) of the intake system during the intake valve opening period.

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

In the present invention, performing control using the control valve to delay the intake air introduction start timing means performing control to change the effective valve opening period θe in equation (1). As a result, the control of the present invention makes it possible to obtain a synchronized rotational speed in a wide rotational speed range, and to obtain a desired filling efficiency increasing effect by pressure waves in each of different rotational speed ranges.

Furthermore, in a preferred embodiment of the present invention, in view of the fact that at high rotation speeds, the delay control by the control valve increases passage resistance, which is rather harmful, the control is controlled to cancel the delay control by the control valve. . This expands the effective valve opening period, that is, θ in equation (1) above.
The intake system should be configured so that e increases, passage resistance decreases, a large amount of intake air can be introduced, and the intake system has a natural frequency that allows pressure wave synchronization rotation speed to be obtained in such an operating region. Therefore, the dynamic effect of intake air can also be obtained, and the filling efficiency can be further improved.

Furthermore, since the pumping loss increases at low loads and has an adverse effect on fuel efficiency, the delay control is similarly canceled. Therefore, according to the present invention, it is possible to ensure a sufficient amount of intake air at high rotation speeds, and
It is also possible to prevent a decrease in fuel efficiency at low loads.

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

Referring to FIGS. 1 and 2, the engine 1 of this example is as follows:
It is a four-cylinder engine, and four cylinder bores 3 are formed in a cylinder block 2, and a piston 4 is arranged in each cylinder bore 3 so as to be able to reciprocate. A cylinder head 5 is connected above the cylinder block 2 , and a space formed by the space above the piston of the cylinder bore 3 and the lower recess of the cylinder head 5 constitutes a combustion chamber 6 .

An intake boat 7 and an exhaust port 8 are open in the combustion chamber 6, and an independent intake passage 9 and an exhaust passage 10 are provided in the cylinder head 5 to communicate with the intake boat 7 and the exhaust boat 8.
is formed. The intake boat 7 has an intake valve 11.
However, each exhaust port 8 is associated with an exhaust valve 12. Further, a spark plug 12a is arranged in the cylinder head 5 so that its tip protrudes into the combustion chamber. A manifold is connected to the independent intake passage 9 of each cylinder, and a fuel injection nozzle 12b is attached near this connection. The independent intake passages 9 of each cylinder are connected to a rotary valve 18 arranged on the upstream side so as to communicate each intake passage 9, and the rotary valve 18 has a cylindrical structure as shown in FIG. The peripheral wall communicates with the intake passage 9 of each cylinder at a predetermined timing. In this manner, an opening 21 that communicates the upstream and downstream sides of the independent intake passage 9 is provided at a position corresponding to each cylinder so as to pass through the low-replacement valve 18. In this example, ignition is performed in the order 1-3-4-2, so 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 adjusted. are formed with the same orientation. On the downstream side of the rotary valve, each independent intake passage 9 has a bypass passage 1
9, and the bypass passage 19
Bypass valves 20 are respectively attached to the connection portions between the intake passages 9 and the intake passages 9.

In the structure of this example, first, the first,
The independent intake passages 9 of the fourth cylinder, and the second and third cylinders merge on the upstream side of the rotary valve 18 to form a common intake passage 9a, and further upstream, the two common intake passages 9a merge. A main intake passage 13 is formed.

An air cleaner 14 is installed at the upstream end of the main intake passage 13, and an air flow meter 15 is installed downstream of the air cleaner 14 to measure the intake air flow rate.

Further, a throttle valve 17 is arranged in each common intake passage 9a.

As shown in FIG. 11, the rotation shaft 1 of the rotary valve 18
8a is connected to a pulley 23 via an advance mechanism 22. The pulley 23 is connected via a belt 26 to a drive pulley 25 attached to the end of the crankshaft 24. In this example, if the open state of the rotary valve 18 can be obtained every half rotation, the diameter is twice that of the pulley 25.
Therefore, the pulley 23 rotates at half the speed of the pulley 25. The advance mechanism 22 includes a pulley 23
A helical gear 27 attached to the end of the rotating shaft 23a of
, a helical gear 28 attached to the end of the rotating shaft 18a of the rotary valve 18 and disposed opposite the helical gear 27 on the pulley 23 side, and a helical gear 27.
and an adjustment piece 29 that meshes with 28. Adjustment piece 29
The meshing position with the helical gears 27 and 28 can be changed in the direction of the rotation axis of the rotary valve 18,
When the adjusting piece 29 moves in the axial direction and the meshing position changes, the relative rotational position with the helical gears 27 and 28 changes,
This causes the amount of advance angle to change. An actuator 30 is provided to adjust the axial position of the adjustment piece 29, and this actuator is preferably operated by a command signal from a control unit 31 incorporating a microcomputer. There is. In this example, the control unit 31 includes:
A signal representing the engine rotational speed is input, and the control unit 31 determines the amount of advance according to this rotational speed signal, and drives the advance angle mechanism 22 via the actuator 30. Mata, control unit 3
1 is designed so that the engine load signal is also input,
The control unit 31 outputs a command signal to the actuator 20a of the bypass valve 20 to open the bypass valve 20 in a predetermined operating range according to the rotation speed and the load value.

In the above structure, the rotary valve 18 rotates at half the speed of the crankshaft 24 in this example. Therefore, the timing at which 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, corresponds to the opening period of the intake valve 11 of each cylinder.

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, and therefore, this period becomes the effective valve opening period. Referring to FIG. 4 in conjunction with FIG. 4, the opening period of the rotary valve 180 is changed according to the engine speed, and as the speed increases, the rotary valve 180 opens as shown by the broken line in the figure. The opening timing of the intake valve 11 is set to approach the opening timing of the intake valve 11. On the other hand, when the engine is running at low speed, the opening timing of the rotary valve 18 is shifted to the delayed side by the operation of the advance mechanism 22, as shown by the solid line in the figure. When the low-resolution valve 18 opens, intake air is actually introduced into the combustion chamber 6, but when the low-resolution valve 18 opens, a negative pressure wave of the intake air is generated on the downstream side of the low-resolution valve 18.

This negative pressure wave propagates upstream in the intake passage 13 and reaches the confluence point 9b of the common intake passage 9a.

In this configuration, the confluence point 9b of the two common intake passages 9a
, the first and second components whose phases are shifted by half a wavelength from each other
The negative pressure waves of the cylinder and the third and fourth cylinders will interfere with each other. As a result, the interfering negative pressure waves cancel each other out and are reversed to generate a positive pressure wave, as shown in FIG.

Therefore, when the intake passages 9 of cylinders in which the generated negative pressure waves have a phase relationship reversed to each other are connected to face each other, the confluence point 9b constitutes an inversion part that inverts the negative pressure waves. The positive pressure wave reversed at this junction propagates downstream within the intake passage 9a19 and finally reaches the combustion chamber 6.

In this example, the intake system is configured so that this positive pressure wave reaches the combustion chamber 6 at the end of the intake stroke, and thereby, by utilizing the pushing effect of the intake air due to the positive pressure wave, high filling efficiency of the intake air is achieved. can be obtained. Considering that the larger the amplitude of the negative pressure wave generated when the rotary valve 18 is opened, the larger the reverse positive pressure wave will be generated, resulting in a larger filling efficiency increasing effect, in this example, the piston speed is slow, and therefore , the opening timing of the rotary valve 18 is set to TDC at low rotation speeds when the generated negative pressure waves tend to be small.
It is configured to delay the wave and form a larger negative pressure wave. Furthermore, the engine rotational speed at which the filling rate increasing effect due to the pressure waves can be obtained, that is, the tuned rotational speed N (rpm
) is expressed as N=θe·ν/6 as a function of the effective valve opening period θe (deg) and the natural frequency ν()lz) of the intake system. In the device of this example, the advance angle mechanism 22 is Since the effective valve opening period θe is changed according to the change in rotation speed, it is possible to obtain a synchronized rotation speed over a wide rotation speed range. The effect of increasing the filling rate can be obtained. In this example, since the negative pressure waves cancel each other out at the reversal section, pressure fluctuations do not propagate to the upstream side.

In addition, in a high engine speed range, if the low-return valve is controlled to the lag side as described above, the passage resistance increases, which may actually have an adverse effect on ensuring a high filling amount. Therefore, in this example, when the engine speed is high, the actuator 20a is operated to open the bypass valve 20 and intake air is also introduced from the bypass passage 19.

This makes it possible to solve the problem of insufficient air intake at high engine speeds. Furthermore, if the above-mentioned control is performed to delay the opening timing of the low-return valve 18 when the engine is running at relatively low speeds and under low load, pumping loss will increase and the deterioration of fuel efficiency will become noticeable. By opening the bypass valve 20 and introducing intake air from the bypass passage 19, the bypass valve 20 is substantially opened.
8 delay control is canceled.

Referring to FIGS. 6 and 7, another embodiment of the invention is shown. Engine 1 in this example is 1-3 similar to the previous example.
It is a four-cylinder engine with a firing order of -4-2. In the intake device of this example, the first,
The independent intake passages of the fourth cylinder and the second and third cylinders are connected to form two common intake passages 9a', and these common intake passages 9a' are connected upstream to the main intake passage 13. . In this example, the common intake passage 9
A cylindrical rotary valve 18' is arranged at each branch point from a+ to the independent intake passage 9. In the structure of this example, an auxiliary reflection section 16 is provided upstream of the throttle valve in the main intake passage 13 to attenuate pressure waves propagated upstream. This effectively suppresses pressure fluctuations from propagating further upstream beyond this auxiliary reflection section 16,
Furthermore, the air flow meter 15 disposed on the upstream side is not adversely affected.

Referring to FIG. 8, yet another embodiment of the present invention is shown. The engine in this example is 1-2-3-4-5
It is a cylinder engine with -6 firing order. In this example, cylinders whose intake strokes do not interfere with each other are divided into two groups of three. That is, the 11th, 3rd,
The fifth cylinder is included in the first group 32, and the second, fourth, and sixth cylinders are included in the second group 33. and,
A common intake passage 9a'' is provided for each group 32, 33, and the independent intake passages 9 belonging to the group are connected to the common intake passage 9a'', and the independent intake passages 9a'' are connected to the common intake passage 9a''. A rotary valve 18'' is arranged at each branch point to 9. 2
The two common intake passages 9a" merge into the main intake passage 13 at the upstream side. Further, in the structure of this example, the two common intake passages 9a" are located downstream of the merging point 9b'' to the main intake passage 13. A communication passage 34 that communicates the two with each other is formed, and an on-off valve 35 that opens and closes the passage 34 is provided in the communication passage 34. This on-off valve 35 is opened and closed by a command signal from the control unit 31. The control unit 31 outputs a command signal to open the on-off valve 35 in a relatively low engine speed range. This is performed at the timing shown in FIG. The intake negative pressure waves generated in each intake stroke are 2 in reverse phase relation.
It propagates upstream in the two common intake passages 9a'', and the on-off valve 3
5 are open in the communication path 34, and when closed, they interfere and invert at the confluence point 9b'' to form a positive pressure wave. Therefore, in the structure of this example, the vibration system of the pressure wave is Since the switching is possible, the natural frequency ν can be changed in the relational expression N=θe·ν/6.As a result, the intake system of this example can control the effective valve opening period θe. Combined with this, it is possible to obtain a tuned rotation speed over a wider rotation speed range.

In addition, the structure of this example includes an auxiliary reflection section 16'' branched from the main intake passage 13 and having a certain volume on the upstream side of the throttle valve 17. This makes it possible to further enhance the reversal effect and to Furthermore, it is possible to effectively suppress the propagation of pressure fluctuations in the intake air to the upstream side.

In the above embodiments, an example in which the present invention is applied to a reciprocating engine has been described, but the present invention can be similarly applied to a rotary piston engine.

[Brief explanation of drawings]

FIG. 1 is an overall schematic diagram of an engine according to an embodiment of the present invention, FIG. 2 is a partial sectional view of the engine in FIG. 1, and FIG.
FIG. 4 is a graph showing the valve opening timing, FIG. 5 is a graph showing the interference state of negative pressure waves, and FIG. 6 is a perspective view of the rotary valve. 7 is a partial sectional view of the engine shown in FIG. 6, FIG. 8 is a schematic view of an engine showing still another embodiment of the invention, and FIG. 9 is a partial sectional view of the engine shown in FIG. 3 is a graph showing valve timing of the engine shown in FIG. 1... Engine, 2... Cylinder block, 3... Cylinder bore, 4...
... Piston, 5 ... Cylinder head,
6...Combustion chamber, 9...Independent intake passage, 9 as 9 a', 9 a''...Common intake passage, 10...Exhaust passage, 13...
・Main intake passage, 14... Air cleaner, 15... Air flow meter, 16.16"
...Auxiliary reflector, 17...Throttle valve, 18.18', 18"...Lower valve, 19...Bypass passage, 20...・
Bypass valve, 22... Advance angle mechanism, 31. Old control unit, 34... Communication passage, 35... Open/close valve. Figure 1 Figure 2 Figure 3 Figure 4 Figure 7

Claims (1)

[Claims] An intake port that opens and closes in synchronization with the rotation of the engine, and an intake port provided in an intake passage upstream of the intake port, at least at low rotation speeds and high loads, the intake passage is opened after the opening timing of the intake port and at suction top dead center. a control valve that opens later to delay the intake start timing; and an inversion section that is provided in an intake passage upstream of the control valve and that reverses an intake negative pressure wave that occurs downstream of the control valve when the control valve is opened. The reversing section includes:
1. An intake system for a multi-cylinder engine, characterized in that intake passages are connected upstream of a control valve so that the intake negative pressure waves having mutually reversed phases interfere with each other.