JPH0686813B2 - Engine intake system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an engine intake device, and more particularly to an improvement of an engine intake device for improving combustibility in a low load region and reducing pumping loss.

(Prior Art) Conventionally, as an intake system for an engine of this type, as disclosed in, for example, Japanese Patent Laid-Open No. 58-23245, a shutter valve that opens at an accelerator pedal opening of a predetermined opening or more is provided in an intake passage. Placed in the bypass passage of the minor diameter that bypasses the shutter valve, 1/2 of the rotation of the cam shaft
A rotary valve that serves as a timing valve that rotates at a rotational speed ratio of 3 is arranged, and in a low load range where the accelerator pedal opening is less than a predetermined opening, the intake valve is closed by the closing operation of the shutter valve to supply intake air only from the bypass passage. By increasing the flow velocity of intake air to generate swirl of intake air to improve combustibility, the rotary valve is closed in the middle of the intake stroke to reduce pumping loss and improve fuel efficiency. It is known to have been made. Further, in the above-mentioned one, when the accelerator pedal is depressed from the low load range to a predetermined opening or more at a high load, the shutter valve is opened to open the intake passage, so that the intake air is also supplied from the bypass passage together with the bypass passage. It is supplied and the output is improved.

(Problems to be Solved by the Invention) In an intake system for an engine equipped with a shutter valve and a rotary valve as described above, when the shutter valve is opened at a predetermined accelerator pedal opening, the intake stroke of the rotary valve is midway during a low load. Although the pumping loss is reduced by the so-called Miller cycle due to the closing of the valve, when the accelerator pedal opening reaches a predetermined opening by opening the shutter valve by depressing the accelerator pedal, the intake air is supplied from the intake passage. The intake end timing suddenly changes from the middle of the intake stroke to the end of the normal intake stroke, and the Miller cycle is rapidly switched to the normal cycle (Otto cycle), resulting in torque shock and a smooth increase in engine output. The drawback is that it does not exist.

The present invention has been made in view of such a point, and its object is to delay the valve closing timing of a timing valve such as a rotary valve in accordance with an increase in the accelerator pedal opening so as to approach the end of the intake stroke. The purpose is to switch from the mirror cycle to the auto cycle as smoothly as possible with the opening operation of the shutter valve to prevent the occurrence of torque shock in the engine and to obtain a smooth increase characteristic of the engine output. .

By the way, according to such an intake device, when accelerating by depressing the accelerator pedal in the low load region, the closing timing of the timing valve is delayed in accordance with the increase of the accelerator pedal opening, so that the intake air supplied from the bypass passage is Although the amount of air apparently increases, the timing valve such as a rotary valve temporarily stops the flow of intake air due to its structure, so the intake air amount does not immediately increase due to the passage resistance of this timing valve, so it is sufficient. Acceleration response is not obtained.

Therefore, a further object of the present invention is to improve the responsiveness of the intake air amount by supplying intake air also from the intake passage during acceleration in the low load region.

(Means for Solving the Problem) In order to achieve the above object, a solution means of the present invention is a shutter valve which is arranged in an intake passage and opens and closes the intake passage,
A timing valve that is arranged in a bypass passage that bypasses the shutter valve and that opens and closes the bypass passage, and closes the shutter valve in a low load range where the accelerator pedal opening is less than a predetermined opening and also uses the timing valve to perform an intake stroke. It is assumed that the engine intake system is closed halfway. Then, a timing valve control means for delaying the closing timing of the timing valve in the low load range according to an increase in the accelerator pedal opening, an acceleration detection means for detecting the acceleration time in the low load range, and an acceleration detection means of the acceleration detection means. An acceleration correction means for receiving the output and opening the shutter valve at the time of acceleration in a low load region is provided.

(Operation) According to the present invention, in the present invention, in the low load region below the predetermined accelerator pedal opening, the shutter valve is closed and the intake air is supplied only from the bypass passage, so the intake flow velocity becomes faster, The swirl is generated to improve the combustibility, and the timing valve is closed in the middle of the intake stroke to form a Miller cycle, so that pumping loss is effectively reduced and fuel efficiency is improved.

Further, when the accelerator pedal opening is increased, the intake air amount is gradually increased in the low load region due to the gradual delay of the valve closing timing of the timing valve, and at the predetermined accelerator pedal opening, the valve closing timing approaches the end of the intake stroke, Since the shutter valve starts to open at this point, the switch from the Miller cycle to the Otto cycle is performed as smoothly as possible, intake air is also supplied from the intake passage to increase the intake air amount, and as a result, The engine output will increase smoothly without torque shock.

Further, at the time of acceleration in the low load region, the shutter valve is forcibly opened and the intake air is smoothly supplied from the intake passage having a small passage resistance, so that the acceleration response is improved.

(Example) Hereinafter, the Example of this invention is described based on drawing.

1 and 2 show an embodiment applied to an intake device of a 4-cylinder 4-cycle engine. In the figure, 1 is the first
An engine 2 having fourth cylinders 1a to 1d is a combustion chamber formed in each cylinder 1a to 1d of the engine 1, and an intake port 3 and an exhaust port 4 are opened in each combustion chamber 2, An intake valve 5 is provided at the opening of the intake port 3 to the combustion chamber 2, and an exhaust valve 6 is provided at the opening of the exhaust port 4 to the combustion chamber 2.

Further, 10a to 10d are intake passages, one end of which communicates with the atmosphere through an air cleaner 14 and the other end of which opens into each combustion chamber 2 through an intake port 3 to supply intake air to each cylinder 1a to 1d of the engine 1. In the vicinity of the intake port 3 of each of the intake passages 10a to 10d, there is a shutter valve 11a for opening and closing the intake passages 10a to 10d.
~ 11d is located. The shutter valves 11a to 11d
Are connected to a valve shaft 12 arranged in the cylinder column direction so as to be interlocked in series. Further, fuel injection valves 13a to 13d are respectively arranged immediately downstream of the shutter valves 11a to 11d of the intake passages 10a to 10d to inject and supply fuel.

In each of the intake passages 10a to 10d, the first to fourth bypass passages 15a for connecting the upstream side of the shutter valves 11a to 11d of the intake passages 10a to 10d and the intake port 3 by bypassing the shutter valves 11a to 11d. ~ 15d is provided. Each of the bypass passages 15a to 15d has a cross sectional area of the intake passages 10a to 1d.
It is set smaller than 0d, and its downstream end opening is open in the circumferential direction of the combustion chamber 2, and the intake air is sucked into the combustion chamber 2 through the bypass passages 15a to 15d. It is designed to generate an intake swirl that swirls along the circumferential direction.

Then, in the middle of each of the bypass passages 15a to 15d, one rotary valve 18 as a timing valve rotatably arranged via a sleeve 17 in a cylindrical member 16 arranged in the cylinder column direction is commonly interposed. It is set up. The rotary valve 18 is composed of a hollow body having an opening on the side of the fourth cylinder 1d, and its end on the side of the fourth cylinder 1d is closed by a closing member 19, so that a bag-shaped intake air supply passage 20 is provided inside. A portion corresponding to the opening period of the intake valve 5 is notched in the circumferential direction in the angular range corresponding to the intake stroke of the corresponding cylinders 1a to 1d in the outer peripheral portion that is formed and faces the bypass passages 15a to 15d. An opening 18a is formed. Then, when the rotary valve 18 rotates, each opening 18a on the outer periphery of the rotary valve 18 communicates with the bypass passages 15a to 15d on the downstream side of the rotary valve 18, and the intake air is bypassed according to the open / close state of the intake valve 5. It can be supplied to the combustion chamber 2 through the passages 15a to 15d.

The end of the rotary valve 18 on the first cylinder 1a side is
It is connected via a helical gear mechanism 23 to a pulley 24 for rotationally driving the rotary valve 18 so as to be relatively displaceable. The pulley 24 has a belt between it and a pulley 26 of the same diameter, which is provided at an end of a cam shaft 25 arranged in the cylinder row direction above the combustion chamber 2.
27 is wound, and the rotary valve 18 is rotationally driven by the rotation of the cam shaft 25. Further, each opening 18a of the rotary valve 18 has a bypass passage 15a to 15d at an initial position when the accelerator pedal is not depressed.
Are pre-positioned so as to be closed at a predetermined time during each intake stroke.

Further, on the valve shaft 12 of the shutter valves 11a to 11d, the shutter valves 11a to 11d are provided at their end portions on the first cylinder 1a side.
An actuator 30 for rotatively displacing the rotary valve 18 is provided, and the helical gear mechanism 23 operates the helical gear mechanism 23 to change the relative rotational position between each opening 18a of the rotary valve 18 and its driving pulley 24. An actuator 31 for changing is provided. Both actuators 30,3
The operation of 1 is controlled by a controller 32 including a CPU and the like.

The controller 32 includes a crank angle sensor 33 for detecting a crank angle, an air flow sensor 34 for detecting an intake air amount immediately downstream of the air cleaner 14, and a negative air pressure sensor for detecting an intake negative pressure downstream of the rotary valve 18 in the bypass passage 15a. Pressure sensor 35 and water temperature sensor 36 for detecting engine cooling water temperature
And detection signals of the accelerator pedal opening sensor 37 for detecting the accelerator pedal opening.

Next, the operation of the controller 32 will be described based on the flowchart of FIG. First, after starting, in step S ₁ , the accelerator pedal opening θ is read from the accelerator pedal opening sensor 37, and in the next step S ₂ , the accelerator pedal opening θ is the boundary between the low load region and the high load region. Is smaller than the accelerator pedal opening intermediate value θ _A corresponding to.

Then, when it is determined YES in step S ₂ that θ ≦ θ _A, it is determined to be in the low load region, and next step S ₃
The process advances, or the rate of change of the accelerator pedal opening in step S _3, the _{Δθ = (θ 1 -θ 2)} / (dt 1 -dt 2), larger than the set value kθ corresponding to the change speed during acceleration Whether or not to compare is determined. Then, in this step S ₃ , Δθ <k
If NO is determined as θ, it is determined that it is not during acceleration, and as shown in FIG. ₄ , the shutter valves 11a to 11d are closed so as to close the shutter valves 11a to 11d in step S4.
Controls the actuator 30 of the rotary valve
The valve closing timing of 18 is gradually delayed according to the increase of the accelerator pedal opening, and at a predetermined accelerator pedal opening θ _A , the valve closing timing coincides with the end of the intake stroke, and the opening period of the rotary valve 18 is changed to the intake valve 5 opening period. After controlling the actuator 31 of the rotary valve 18 so as to substantially overlap the valve opening period, the process returns to step S ₁ .

On the other hand, when it is judged NO in the above step S ₂ that θ> θ _A, it is judged to be in the high load region, and as shown in FIG. 4, the closing timing of the rotary valve 18 is set to the accelerator pedal in step S ₅ . shutter valve to increase in response to opening of the shutter valve 11a~11d the increase in the accelerator pedal opening to control the actuator 31 of the rotary valve 18 so as to kept the closing timing of opening theta _a 11a to After controlling the actuator 30 of 11d, the process returns to step S ₁ .

On the other hand, when it is determined YES in step S ₃ that Δθ ≧ kθ, it is determined that the acceleration is in the low load region, and in step S ₆ , the opening timing of the rotary valve 18 is set to the low value in step S ₄ . The shutter is controlled in the same manner as the control in the load range, and as shown by the broken line in FIG. 4, the shutter valves 11a to 11d are opened simultaneously with acceleration, and the shutter opening is increased in accordance with the increase of the accelerator pedal opening. After controlling the actuator 30 of the valves 11a to 11d, the process returns to step S ₁ .

In the above flow, at low load region constitutes a timing valve control means 40 for delaying according to closing timing of the rotary valve 18 to increase the accelerator pedal opening in step S _4, low in steps S ₂ and Step S ₃ with constituting the acceleration detecting means 38 for detecting the time of acceleration in the load region, constitute the acceleration correction means 39 for opening operation of the shutter valve 11a~11d during acceleration in the low load region in step S _6.

In FIG. 1, reference numeral 41 denotes an assist air passage for supplying assist air to the vicinity of the injection port 13a of each fuel injection valve 13, and one end of the assist air passage 41 is a collection portion of the intake passages 10a to 10d. It communicates with the air cleaner 14 arranged upstream, and the other end communicates with the vicinity of the nozzle 13k of the fuel injection valve 13 through a large number of small holes 42a provided in the cap 42 crowned at the tip of the fuel injection valve 13. is doing. Then, when the intake air is supplied only from the bypass passages 15a to 15d, that is, when there is no intake air flow around the fuel injection valve 13, the fuel from the fuel injection valve 13 is finely divided by the assist air from the assist air passage 41. The combustion of the air-fuel mixture in the combustion chamber 2 is favorably performed. Further, a control valve 43 for adjusting the amount of assist air is provided in the middle of the assist air passage 41, and the operation of the control valve 43 is controlled by the controller 32.

Therefore, in the above embodiment, the shutter valve 11
At a low load when a to 11d are in the closed state, intake air is supplied to the combustion chamber 2 only from the bypass passages 15a to 15d, so that the intake flow velocity becomes faster and swirl is generated in the intake air to improve combustibility. . Further, since the rotary valve 18 sets the intake end timing in the middle of the intake stroke,
Pumping loss is reduced, and as a result, fuel efficiency is improved. Moreover, at that time, although the effective compression ratio in the next compression stroke decreases with the end of intake in the middle of the intake stroke, the combustion temperature of the air-fuel mixture decreases, but swirl is generated in the intake air. Therefore, the flammability is ensured satisfactorily.

Further, when the accelerator pedal is depressed, the closing timing of the rotary valve 18 is controlled to be delayed according to the increase of the accelerator pedal opening, and the intake air amount gradually increases, and thereafter, at the predetermined accelerator pedal opening θ _A , the rotary valve 18 is rotated. When the closing timing of the valve 18 coincides with the end of the intake stroke and the opening period of the rotary valve 18 substantially overlaps the opening timing of the intake valve 5, the opening of the shutter valves 11a to 11d starts from this point. The intake air amount is gradually increased and the engine output is improved because the increase control is gradually performed in accordance with the increase in the engine speed.

At that time, the opening of the shutter valves 11a to 11d is started when the closing timing of the rotary valve 18 coincides with the end of the intake stroke at the position of the predetermined accelerator pedal opening θ _A.
The so-called Miller cycle can be smoothly switched to the Otto cycle to prevent torque shock, and thus a smooth increase in engine output can be ensured.

Further, at the time of acceleration in the low load region, the shutter valves 11a to 11d are forcibly opened simultaneously with the acceleration, so that in addition to the supply of intake air from the rotary valve 18, a large amount of intake air is also supplied from the intake passages 10a to 10d having a small passage resistance. Is smoothly supplied, the response of the intake air amount is enhanced, and the acceleration response can be improved.

Further, since the rotary valve 18 rotates 1: 1 with respect to the cam shaft 25, the rotary valve 18 is opened compared to the conventional one that rotates at a rotational speed ratio of 1/2 with respect to the cam shaft 25. The effective opening area of the bypass passages 15a to 15d during the period is increased, and the intake air amount can be increased. Moreover, as the rotary valve 18 rotates 1: 1 with respect to the camshaft 25, the positions of the openings 18a of the rotary valve 18 are determined by a predetermined cylinder (for example, the first cylinder 1a) and a cylinder delayed by two strokes (the fourth cylinder 1d). ), The opening 18a corresponding to a predetermined cylinder (for example, the first cylinder 1a) communicates with the first bypass passage 15a on the downstream side of the rotary valve 18. Sometimes 2 for the first cylinder 1a
The opening 18a corresponding to the fourth cylinder 1d whose stroke is delayed communicates with the fourth bypass passage 15d on the upstream side of the rotary valve 18, and the intake air passes from the fourth bypass passage 15d through the intake air supply passage 20 in the rotary valve 18 to the first bypass passage 15d. Since it is supplied to the first bypass passage 15a, it is possible to simplify the structure by eliminating the need for other piping.

(Effects of the Invention) As described above, according to the intake system for an engine of the present invention, in the low load range, intake swirl is generated by the supply of intake air only from the bypass passage to improve the combustibility and the timing. While reducing the pumping loss by closing the valve during the intake stroke of the valve, when the accelerator pedal is depressed, the intake air amount is increased to the delay control of the closing timing of the timing valve to change from the Miller cycle to the Otto cycle. Since switching is performed smoothly, torque shock can be prevented and a smooth increase in engine output can be secured.Moreover, when accelerating in the low load range, the shutter valve is forcibly opened to move from the intake passage. Since it also supplies intake air, it is possible to improve the response of the intake air amount and improve the acceleration response of the engine. It is capable of

[Brief description of drawings]

1 shows an embodiment of the present invention, FIG. 1 is an overall configuration diagram when applied to an intake device of a 4-cylinder engine, FIG. 2 is a transverse sectional view, and FIG. 3 is a flow chart diagram for explaining the operation of a controller. FIG. 4 is a diagram showing opening characteristics of the rotary valve and the shutter valve with respect to an increase in accelerator pedal opening. 1 ... Engine, 2 ... Combustion chamber, 5 ... Intake valve, 10a-1
0d ... intake passage, 11a-11d ... shutter valve, 15a-1
5d ... Bypass passage, 18 ... Rotary valve, 20 ... Intake supply passage, 32 ... Controller, 33 ... Crank angle sensor, 34 ... Negative pressure sensor, 38 ... Acceleration detection means, 39 ...
... acceleration correction means, 40 ... timing valve control means.

Claims (1)

[Claims] 1. A shutter valve which is arranged in an intake passage and opens and closes the intake passage, and a timing valve which is arranged in a bypass passage bypassing the shutter valve and opens and closes the bypass passage. In an intake system of an engine in which the shutter valve is closed in a low load range less than the opening degree and the timing valve is closed in the middle of the intake stroke, the closing timing of the timing valve is set to the accelerator pedal opening degree in the low load range. Timing valve control means for delaying in accordance with an increase, acceleration detection means for detecting acceleration time in a low load range, and acceleration correction means for receiving the output of the acceleration detection means and opening the shutter valve during acceleration in a low load range. An intake system for an engine, which is characterized by being equipped with.