JPS6287611A - Suction device for engine - Google Patents

Abstract

PURPOSE:To aim at improvement in suction efficiency and stabilization in combustion, by installing a rotary on-off valve in a suction passage, synchronizing it with an engine speed, and making its on-off timing variable, while installing a suction turnover part at the upstream of the on-off valve, and also installing a swirl forming port in addition. CONSTITUTION:A rotary on-off valve 18 is installed in a converging part at the upstream of an independent suction passage of each cylinder 3, rotating it by a crankshaft 24 of an engine via a belt 26. An on-off timing adjuster 22 is installed in this driving system, whereby the suction passage is made so as to be opened by a control unit 31 at the specified timing after opening a suction valve 7 according to engine load and speed. At the time of opening, suction pulsation pressure is turned over at a part of an expansion chamber 16 at the upstream of the valve 18, thus charging efficiency is improved. A suction flow velocity at that time is speedy, making it into a high swirl by a swirl port form, and thereby combustion is stabilized. At the time of driving when neutralizing a function of the on-off valve 18, a valve 20 in a bypass passage 19 is opened.

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 the filling efficiency by utilizing the effect of pressure waves of intake air, the following problems arise. When the engine speed decreases, the downward speed of the piston decreases, and therefore the generated negative pressure wave decreases, and the effect of improving the filling rate also decreases. In addition, while the propagation of pressure waves occurs 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 January male to obtain the direction effect of filling efficiency.

In view of these circumstances, Japanese Patent Application Laid-Open No. 55-107018 discloses an intake air reservoir provided in the intake passage upstream of the intake valve, and an intake passage that communicates the cylinder with the intake air reservoir, an air supply control valve having a valve plate that rotates at the same speed as the rotational speed of the crankshaft or one-half the rotational speed of the crankshaft, and the cylinder and the air supply reservoir are communicated with each other according to the rotational speed of the crankshaft through the control valve. An intake structure for an engine has been disclosed in which a large intake pressure fluctuation is caused by controlling the intake air pressure, and an effect of increasing the filling rate due to the pressure wave of the intake air is obtained.

(Problems to be Solved by the Invention) The device disclosed in the above-mentioned Japanese Patent Application Laid-open No. 55-107018 controls the opening timing of the intake control valve to be delayed at low engine speeds, thereby generating a large negative pressure wave. , which is reversed in the charge reservoir and introduces a large reflected positive pressure wave into the combustion chamber, thereby
The filling efficiency is increased at low rotation speeds. However, there is a problem in that knob kinging is likely to occur at low rotation speeds, especially during high load operation, and the device disclosed above does not take countermeasures against knob kinging. It is impossible to achieve the intended purpose.

(Means for solving the above problem) The present invention is configured to solve the above problem, and the intake device of the present invention includes at least one intake port that opens and closes in synchronization with the rotation of the engine. , a control valve that is provided in the intake passage upstream of the intake port and controls the intake passage to open after the intake port opening timing and after the suction dead center to delay the intake start timing; and at least during low load operation. a canceling unit for canceling the delay control of the control valve; and an inversion unit provided in the intake passage upstream of the control valve and inverting an intake negative pressure wave generated downstream of the control valve when the control valve is opened. We are prepared.

The intake port of the device of the present invention is configured as a so-called swirl port, which introduces intake air substantially tangentially to the wall surface of the combustion chamber so as to generate a swirl within the combustion chamber.

The control valve of the present invention opens later than the intake top dead center, that is, TDC, during low-speed, high-load operation, etc., thereby generating a large pressure wave and exerting a pushing effect on intake air at the end of the intake stroke. There is.

In this case, intake air is introduced through the swirl port substantially tangentially to the wall surface of the combustion chamber. Further, the opening timing of the control valve may be controlled to have a certain deviation from the opening timing of the intake valve, or may be controlled in stages or in accordance with changes in engine speed and load. It may be changed continuously. 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 is, for example,
:'r i Set the valve opening period of the control valve to be longer than the intake valve, and use the advance mechanism to match the opening period of the control valve to the intake valve at low loads and high rotations. It should be configured as follows. Additionally, a bypass passage that bypasses the 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 at times of low load, high rotation, etc. . moreover,
A bypass passage is provided to communicate the independent intake passages for each cylinder downstream of the control valve, and a bypass valve is installed in the passage.
This valve may be opened at times of low load, high rotation, etc., and intake air may be introduced through the intake passages of other cylinders. Also,
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 reversal section may be constructed by forming a container section having a constant volume in the intake passage common to each cylinder, or may be constructed by forming a container section having a fixed volume in the intake passage common to each cylinder, or may be constructed by forming a cylinder section in which the phase of the generated negative pressure wave is shifted by half a wavelength. It is also possible to connect the tubes so that they face each other.

(Effects of the present invention) According to the present invention, during medium-high load operation at low and medium rotation speeds, the control valve is controlled to open later than the suction top dead center, and a large A negative pressure wave is generated, and this negative pressure wave propagates upstream in the intake passage, reverses at the reversal section, and becomes a positive pressure wave. This positive pressure wave propagates downstream as a reflected wave, pushing intake air into the combustion chamber at the end of the intake stroke. give effect. Due to this effect, the engine according to the present invention can ensure high charging efficiency, and therefore can improve output.

In this case, the intake air is introduced into the combustion chamber at a high flow rate because the introduction timing is delayed and because there is a pushing effect due to the positive pressure wave.

In the present invention, this intake air is tangentially introduced into the combustion chamber through the swirl port, so that the intake air has a high flow rate and there are
A powerful swirl is formed.

As a result, the ignitability of the intake air is improved, and it is possible to eliminate interpressure such as knocking, especially at low rotation speeds and high loads.
It is possible to ensure a high filling rate and effectively improve output.

In a preferred embodiment of the present invention, when the intake air is introduced through the swirl port at high rotation speeds, the air passage resistance increases, the swirl becomes too strong, and in diesel engines, etc., noise problems occur. Taking these circumstances into consideration, the delay control of the intake air introduction start timing by the control valve is canceled.

Furthermore, since the pumping loss increases at low loads and has a negative impact on fuel efficiency, it is desirable to cancel the delay control as well.

In addition, the engine rotation speed (hereinafter referred to as the tuned rotation speed) at which the filling rate can be increased by the pressure waves that generally occur in the intake system.
is expressed by the following relational expression.

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

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 ring.

In the present invention, controlling the intake air introduction start timing to be delayed by the control valve means performing control to change the effective valve opening period θe in equation ( ). Therefore, by determining the structure of the intake system so that a synchronized rotation speed can be obtained in a desired rotation speed range, it is possible to obtain the filling efficiency increasing effect by pressure waves over a wide rotation speed range in each of different rotation speed ranges. .

<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 port 7 and an exhaust port 8 are open 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 exhaust port 8. The intake port 7 in this example is configured as a so-called swirl port that introduces intake air tangentially to the wall surface of the combustion chamber 6. An intake valve 11 is associated with the intake port 7, and an exhaust valve 12 is associated with the exhaust port 8. Further, the cylinder head 5 has a spark plug 12.
a is arranged so that its tip protrudes into the combustion chamber. A manifold is connected to the intake passage 9 of each cylinder, and a fuel injection nozzle 12b is attached near this connection, and the intake passages 9 join upstream to form a main intake passage 13, which extends further upstream. An air cleaner 14 is installed at the upstream end of the main intake passage 13.
An air flow meter 15 for measuring the intake flow rate is provided downstream of the air flow meter 15, and a volume section 1 having a certain capacity for reversing the negative pressure wave generated in the intake system is provided downstream of the air flow meter 15.
6 is provided. Further, a throttle valve 17 is disposed in the main intake passage 13, and a cylindrical rotary valve 18 as shown in FIG. 3 is rotatably disposed at a branch portion downstream of the throttle valve. The intake passages 9 to each cylinder downstream of the branching portion are communicated with each other by a bypass passage 19, and a bypass valve 20 is installed at the connection portion between the bypass passage 19 and each intake passage 9. . In addition, the upstream side of the air pass passage 19 is the main intake passage 1.
3) and the throttle valve 17. Openings 21 communicating with the intake passages 9 of each cylinder at predetermined rotational positions are recessed in the peripheral wall of the low clear XI/shib 18, corresponding to each cylinder. In this example, the ignition is 1
-3-4-2, so in order to avoid interference of each other's intake air, the opening positions for the first and fourth cylinders,
The opening positions for the second and third cylinders are formed in the same orientation.

As shown in FIG.
3a is connected to the pulley 23 via the advance mechanism 22 by 13K. 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, pulley 23 and pulley 25 have the same diameter, and therefore both rotate at the same speed.

The advance mechanism 22 includes a helical gear 27 (attached to the end of the rotating shaft 23a of the pulley 23) and a rotary valve 18.
The helical gear 2 is attached to the end of the rotating shaft 18a and is arranged opposite to the helical gear 27 on the manual pulley 23 side.
8, and an adjustment piece 29 that meshes with both helical gears 27 and 28.
It is equipped with

The adjustment piece 29 can change the meshing position with the helical gears 27 and 28 in the direction of the rotation axis of the rotary valve 18, and when the adjustment piece 29 moves in the direction of the two axes and the meshing position changes, the helical gear The relative rotational position with respect to 27 and 28 changes, and the amount of advance angle changes accordingly. In order to adjust the axial position of the adjustment piece 29,
An actuator 30 is provided, and this actuator is preferably operated by a command signal from a control unit 31 incorporating a microcomputer. In this example, a signal representing the engine rotation speed is input to the control unit 31, and the control unit 31 determines the amount of advance according to this rotation speed signal, and controls the actuator 30.
The advance angle mechanism 22 is driven via. In addition, the control unit 31 is configured such that the engine load signal is also input manually, and the control unit 31 receives the engine load signal manually.
Depending on the load value, the actuator 20 of the bypass valve 20
In a predetermined operating range for a, a command signal is output to open the bypass valve 20.

In the above structure, in this example, the low revalve 18:
It rotates at the same speed as the crankshaft 24.

Therefore, the timing when the opening 21 of the rotary valve 18 communicates with the intake passage 9 of each cylinder, that is, the rotary valve 18
The valve opening period corresponds to the valve 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. If you refer to Fig. 4, the low revalve 1
The opening period of the valve 8 is changed according to the engine speed, and as the engine speed increases, the opening period of the low-return valve 18 changes to the opening period of the intake valve 11, as shown by the broken line in the figure. set to approach. On the other hand, when the engine is running at low speed, the opening timing of the low-return 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, and 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 through the intake passage 13 and reaches the volume portion 16 . In the volume portion 16, the negative pressure wave is reversed and becomes a positive pressure wave, which propagates downstream within the intake passage 13 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. I'm trying to get it. In view of the fact that the greater the amplitude of the negative pressure wave that occurs when the low-pressure valve 18 is opened, the larger the reverse positive pressure wave is generated, resulting in a greater filling efficiency increasing effect (1), in this example, the piston speed is slow; , the opening timing of the valve 18 is delayed to form a larger negative pressure wave at low rotation speeds when the generated negative pressure wave tends to be smaller. The filling rate increasing effect due to il
The engine rotational speed, 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 (Hz) of the intake system. In the device of this example, the advance angle mechanism 22 is used. 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, and as a result, filling is possible over a wide rotation speed range from low to medium rotation speeds The effect of increasing the rate can be obtained.

In this case, in the structure of this example, intake air is introduced through the intake port 7 in a tangential direction to the wall surface of the combustion chamber. In an operating range in which the valve opening timing is delayed and the effective valve opening period is controlled by the low-return valve 18, the intake air flow rate increases, so that the intake air introduced into the combustion chamber generates a strong swirl. As a result, abnormal combustion such as knocking can be prevented, and output can be effectively improved with a commercial efficiency of f4F.

In addition, in the high speed range of the engine, especially if the control is carried out by shifting the low-return valve to the lag side (especially in the case of an intake structure with a swirl port), the increase in passage resistance becomes noticeable. On the contrary, there is a risk that it will be detrimental to securing business funding.

Therefore, in this example, during high rotation, the actuator 20
a to open the bypass valve 20 and introduce intake air from the bypass passage 19 as well.

ing. This solves the problem of insufficient air intake at high rotation speeds.3゜Furthermore,
When the engine speed is relatively low and the load is low, if control is performed to delay the opening timing of the low-return valve 18 as described above, the pumping loss will increase and the deterioration of fuel efficiency will become noticeable. Open the valve 20,
Intake air is also introduced from the bypass passage 11 to substantially cancel the delay control of the low-return valve 18.

Further, referring to FIG. 5, another embodiment of the present invention is shown, in which the intake port 7 is arranged close to the peripheral wall of the combustion chamber 6, and the intake passage 9 is arranged close to the peripheral wall of the combustion chamber 6. It is provided so as to communicate with this intake port 7 along. In this structure as well, the intake air is introduced tangentially to the wall surface, creating a strong swirl.

In the above description, an example having a single intake port has been described, but as shown in FIG. 6, the present invention can also be applied to an engine having a plurality of intake ports. In this example, a large-diameter primary port that introduces intake air in all operating ranges is used. (a) and a small diameter secondary port (7b) that functions only during high-load operation.

In this case, swirl is mainly generated when intake air is introduced from the primary port.

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 low reciprocating 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 cross-sectional view of the engine of FIG. FIG. 5 is a plan view of an engine according to an embodiment of the pond according to the present invention, and FIG. 6 is a plan view of an engine according to a further example of the pond according to the present invention. 1... Engine 2... Cylinder block 3... Cylinder bore 4...
・Piston 5...Cylinder head 6...
...Combustion chamber 9°°°゛'' intake ventilation! i'6 10
...Exhaust passage 13...Main intake passage
14... Air cleaner 15... Air flow meter 16... Volume h4 part 17...
...Throttle valve 18...Lower valve 19...Bypass passage 20...Bypass valve 22...Advance mechanism 31...Control unit TDCBDC crank angle

Claims (1)

[Claims] At least one intake port that opens and closes in synchronization with the rotation of the engine, and the intake passage is provided in an intake passage upstream of the intake port, and opens the intake passage after the intake top dead center after the opening timing of the intake port. a control valve that delays the start timing; a release means that releases the delay control of the control valve at least during low load operation; and a release means that is provided in the intake passage upstream of the control valve and downstream of the control valve when the control valve is opened. and an inversion part that inverts an intake negative pressure wave generated at the side, and the intake port is configured to generate a swirl in the combustion chamber at least in an operating state where the intake start timing is delayed by the control valve. The intake system of the engine.