JPH0633779A - Intake device for diesel engine - Google Patents

Abstract

PURPOSE:To promote the mixing of fuel with air so as to prevent black smoke by providing control means for fully closing the first opening/closing valve and fully opening the second opening/closing valve in a low load region, opening both the first/second opening/closing valves to a half opening or more in an intermediate load region and for fully opening the first opening/closing valve and opening the second opening/closing valve less than the half opening in a high load region. CONSTITUTION:By performing control of fully closing the first intake port 21 and fully opening the second intake port 22 in a low load region, a low swirl is generated. By performing control of opening both the intake ports 21, 22 to a half opening or more in an intermediate load region, an intermediate swirl is generated. By performing control of fully opening the first intake port 21 and opening the second intake port 22 less than the half opening in a high load region, a high swirl is generated. In this way, in the intermediate and low swirls, a necessary intake charge amount can be ensured to improve fuel consumption, and in the high swirl, mixing fuel with air is promoted to improve combustion efficiency, so that an output is improved to prevent generation of black smoke.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine intake device, and more particularly to a helical intake port,
The present invention relates to an intake device for a diesel engine having a tangential intake port.

[0002]

2. Description of the Related Art Conventionally, in a diesel engine in which fuel is injected into a cylinder whose temperature is high by compression and spontaneously ignites, an intake port is a helical port, and a swirl of intake air generated by the helical port causes injection fuel and intake air to be mixed with each other. Is promoted to improve the combustion efficiency, improve the output, and prevent the generation and emission of black smoke to purify the exhaust.

For example, in Japanese Utility Model Laid-Open No. 3-65823, a tangential second branch branched from a manifold common to the first intake port is provided on the swirl downstream side of the helically formed first intake port. It is shown that an intake port is provided, and the first intake port is provided with a control valve that is closed at low load and opened at high load. With this configuration, at the time of high load, the first intake port is opened and a strong swirl is formed, but the air flow from the second intake port weakens this and proper mixing can be performed.

[0004]

However, in the above-mentioned conventional device, only the opening and closing valve is provided in the first intake port formed in a helical shape, and all of high load, medium load and low load are provided. In the above operating range, it is difficult to form a good swirl, and there is a problem that the intake resistance increases and the air charge decreases as the on-off valve opens and closes.

Therefore, the present invention has been made in order to solve the problems of the prior art, and it is possible to secure the intake charge amount by reducing the intake resistance and to form a good swirl according to the load. It is an object of the present invention to provide an intake device for a diesel engine that can be used.

[0006]

In order to achieve the above object, the present invention provides a helical shape in which the axis of the opening extends in the tangential direction of the cylinder and enhances the swirl of the horizontal component orthogonal to the axis of the cylinder. A tangential second intake in which the axial center of the first intake port and the opening extends in the same direction as the first intake port and is directed in the cylinder axial direction from the first intake port to strengthen the swirl of the cylinder axial center component. In a diesel engine intake device having a port,
A first opening / closing valve provided in the first intake port, a second opening / closing valve provided in the second intake port, the first opening / closing valve being fully closed in a low load region, and the second opening / closing valve. Is fully opened, both the first on-off valve and the second on-off valve are half-opened or more in the medium load range, and the first on-off valve is fully opened and the second on-off valve is less than half-open in the high load range. And are characterized by having.

In the present invention thus constructed,
In the low load region (C), only the tangential second intake port having a small intake resistance is fully opened to generate a low swirl. Therefore, since the intake resistance is reduced, the required intake charge amount can be secured, and the low swirl can improve the fuel consumption by increasing the combustion speed without leaning the fuel spray. In the medium load range, the intake resistance is reduced because the first and second on-off valves provided in the first and second intake ports are at least half-opened or more. Therefore, the required intake charge amount can be secured. In addition, a moderate swirl improves fuel efficiency, resulting in
It is possible to prevent the fuel temperature from rising and suppress the generation of nitrogen oxides. In the high load range, the first helical port shape
By fully opening only the intake port, a high swirl with a large swirl ratio is generated. Therefore, while ensuring an appropriate intake charge amount, high swirl promotes mixing of fuel and air to increase combustion efficiency (air utilization rate),
The output can be improved and the generation of black smoke can be suppressed.

Further, according to the present invention, the helical first intake port for reinforcing the swirl of the horizontal component in which the axis of the opening extends in the tangential direction of the cylinder and is orthogonal to the axis of the cylinder, and the axis of the opening are An intake device for a diesel engine, comprising: a tangential second intake port extending in the same direction as the first intake port and directed in the cylinder axis direction from the first intake port to strengthen the swirl of the cylinder axis component, The first provided on the first intake port
The on-off valve, the second on-off valve provided in the second intake port, and the first on-off valve are fully closed in the low load and low rotation range, and the second on-off valve is fully opened, so that the medium load range is low. In the high load high rotation range and the high load high rotation range, both the first opening / closing valve and the second opening / closing valve are half open or more, and in the high load low rotation range the first
And a control means for fully opening the on-off valve and setting the second on-off valve to less than half open.

In the present invention thus constructed,
The first and second on-off valves provided in the first and second intake ports are controlled so as to form a medium swirl region in the high rotation region. That is, in the high rotation range,
By setting both the first and second on-off valves to half open or more, a medium swirl having a medium swirl ratio is generated.
In the high speed region, the swirl tends to be high because the speed of the intake air introduced into the cylinder is high. Therefore, even if the on-off valve is controlled so as to generate the medium swirl, the high swirl can be generated as a result. Further, in the high engine speed range, the intake valve opening time per engine revolution is short, but
By setting both the intake ports of the above to half open or more, the intake charge amount can be secured. This makes it possible to generate a moderately high swirl that avoids overswirl, so that it is possible to improve the output and suppress the generation of black smoke (smoke).

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 is an overall configuration diagram showing an intake device of a direct injection diesel engine, FIG. 2 is a vertical sectional view showing an engine to which an embodiment of the present invention is applied, and FIG. 3 is a plan view showing intake ports and exhaust ports of FIG. It is a figure.

As shown in FIG. 1, the engine 1 has four cylinders 2, and each cylinder 2 has two intake valves and two exhaust valves. Reference numeral 3 is an intake passage, and 4 is an exhaust passage. Reference numeral 5 denotes a high supercharging turbocharger. The high supercharging turbocharger 5 is composed of a compressor 6 arranged in the intake passage 3 and a turbine 7 arranged in the exhaust passage 4.

As shown in FIG. 2, in the engine 1, the center line CL of the cylinder head of the cylinder head 12 corresponding to the opening of the cylinder 2 in the direction orthogonal to the cylinder row arrangement direction.
The two intake ports (the first intake port 21 and the second intake port 22) are arranged on one side and the exhaust ports 31, 32 are arranged on the other side so as to be adjacent to each other with the boundary (see FIG. 3) as the opening. There is. That is, the opening positions of the intake ports 21, 22 and the exhaust ports 31, 32 to the cylinder 2 are arranged substantially symmetrically with the center line CL orthogonal to the cylinder row arrangement direction sandwiched therebetween.

A recess is formed at the center of the top of the piston 16 fitted in the cylinder 2. When the piston 16 is located near the top dead center, the recess and the lower surface of the cylinder head 12 form a combustion chamber 15. Is forming. Intake port 21,
22 is independently communicated with one side surface of the cylinder head 12 orthogonal to the cylinder row arrangement direction via port passages 21A and 22A, respectively, and the exhaust ports 31 and 32 are
The intake ports 21 and 22 are communicated with the side surface of the cylinder head 12 opposite to the communication side via port passages 31A and 32A.

The intake ports 21 and 22 are connected to the port passage 21.
The first intake port 21 on the side closer to the side surface of the cylinder head 12 that is communicated by A and 22A is a helical port in which an opening (port portion 21B) toward the cylinder 2 side is formed in a spiral shape, and the other one The opening portion (port portion 21B) of the 2nd intake port 22 toward the cylinder 2 side is not formed in a spiral shape but is formed by a smooth curve, and the port passage 22A is formed.
Are arranged in a tangential direction of an arc centered on the cylinder center in the opening so as to generate a weak swirl flow along the inner peripheral surface of the cylinder 2 in the same direction as the swirl rotation direction generated by the first intake port 21. It is a tangential port that was created. That is, the first intake port 21 is a port that reinforces the swirl of the horizontal component orthogonal to the cylinder axis, and the other second intake port 22 is oriented in the cylinder axis direction from the first intake port and is oriented toward the cylinder axis. It is a port that strengthens the swirl of the ingredient. Further, the port passage 22A of the second intake port 22 is formed substantially horizontally so as to overlap with the upper side of the port portion 21B of the first intake port 21, and is formed substantially vertically from the port passage 22A via the port portion 22B. It is formed so as to open. Due to the overlapping arrangement configuration of the port passages 21A and 22A, the port passages 21A and 22A can be arranged compactly.

As described above, due to the shape and arrangement of the intake ports 21, 22, the intake air from the first intake port 21 is 21S in FIG. 3 due to its spiral port portion 21B.
A swirl with a small radius is generated, and the second intake port 2
The intake air from 2 causes a swirl with a large radius along the inner peripheral surface of the cylinder head 11 indicated by 22S in FIG. 3 due to the arrangement of the port passage 22A, although the port portion 22B is not spiral, and this swirl , A tumble flow cylinder (swirl of axial center component) which is a vertical swirling flow of the cylinder 2 for flowing into the cylinder through the substantially vertical port portion 22B. Due to the generation of the tumble flow, the second intake port 22 functions as a swirl damping port. As a result, the strongest swirl (high swirl) is generated when the first intake port 21 alone performs the intake, and the second intake port 22 when the intake is simultaneously performed from both the intake ports 21 and 22. The tumble flow generated by ## EQU1 ## weakens the swirl flow generated by the first intake port 21 to generate a medium swirl (medium swirl). Further, when the second intake port 22 is used alone to intake air, the weakest swirl (low swirl) is generated.

Port portion 21 of each intake port 21, 22
Poppet valves 61 and 62, which are open / close valves for opening and closing these intake ports 21 and 22, are arranged at the opening portions of B and 22B to the cylinder 2, and these poppet valves 61 and 62 are provided with push rods. A rocker arm 14, which is oscillated in synchronism with the rotation of the crankshaft of the engine 1 by 13 is pressed to open and close the intake ports 21 and 22.

Cylinder head 1 of intake ports 21, 22
The manifold passages 71, 72 of the intake manifold 70A formed integrally with the surge tank 70 are connected to the side opening of the second side passage 2. The passages 71, 72 are opened and closed in the manifold passages 71, 72, respectively. Openable on-off valves 81, 82 are provided. These on-off valves 81 and 82 are respectively connected to diaphragms 83 and 83 which are actuators, and these diaphragms 83 and 83 are connected to a vacuum pump 84 rotatably driven by a crankshaft of an engine to a solenoid valve 8 respectively.
Negative pressure is supplied via negative pressure supply passages 86, 86 having 5,85. The opening / closing valves 81, 82 are opened / closed depending on whether negative pressure is supplied to the diaphragms 83, 83 by the opening / closing operations of the solenoid valves 85, 85.

The solenoid valves 85, 85 are drive-controlled by a control device 90 as a control means, so that the on-off valves 81, 82 are controlled by the control device 90 for opening / closing operations. On the other hand, at the position corresponding to the center of the cylinder 2 of the cylinder head 12, that is, the center of the combustion chamber 15, a unit injector 91, which is a pressure-accumulation injector having a pressure accumulation tank, has its injection nozzle 91A in the cylinder 2 (combustion chamber 15). The fuel injection pump 92 supplies high-pressure fuel to the unit injector 91.

Fuel injection pump 92
Is for distributing and pumping a predetermined amount of fuel to each cylinder according to the load, and is provided with a rotating member connected to rotate in synchronization with a crankshaft (not shown) of the engine 1, and further, an accelerator pedal It is operated by the AP via a governor (not shown). That is, the fuel injection pump 92 rotates the engine 1 (rotates the crankshaft).
The fuel is pressurized and distributed to each cylinder by a rotating member that rotates in synchronization with, and the injection amount is adjusted by using the operation amount of the accelerator pedal AP as load information.

Further, 93 is a pressure sensor, and this pressure sensor 93 detects the intake pressure in the surge tank 70. If the intake pressure detected by the pressure sensor 93 is equal to or higher than the atmospheric pressure, the high supercharging turbocharger 5 is operating, that is, the supercharging region, and if it is equal to or lower than the atmospheric pressure, the non-supercharging region. The control device 90 receives information on the number of revolutions of the engine 1 from the fuel injection pump 92, information on the operation amount of the accelerator pedal AP, and the pressure sensor 9.
3 obtains information on the operation of the high supercharging turbocharger 5, and based on these information, the intake ports 21, 2
The on-off valves 81, 82 provided in the manifold passages 71, 72 connected to the second valve are controlled to be opened and closed. That is, the fuel injection pump 92 serves as the engine load detecting means and the engine speed detecting means, and the pressure sensor 93 serves as the supercharging area determining means.

The contents of the opening / closing control of the opening / closing valves 81 and 82 according to the embodiment of the present invention will be described below with reference to FIGS. 4 and 5. FIG. 4 is a diagram showing the control contents of the on-off valve in each operating range indicated by the swirl ratio and the engine speed according to the embodiment of the present invention. FIG. 5 is a diagram showing the control contents of the on-off valve in each operating range indicated by the engine load and the engine speed according to the embodiment of the present invention.

First, the contents of FIG. 4 will be described. Here, the swirl ratio is a ratio between the angular velocity of the swirl flow and the engine rotation speed, and the larger the swirl ratio, the stronger the swirl is generated. The average effective passage area is both intake ports 21 and 2.
It is represented by the sum of two average effective passage areas. In FIG.
Point a shows the case where only the first intake port 21 that is a helical port is fully opened, point b shows the case that only the second intake port 22 that is a tangential port is fully opened, and point c shows both intake ports 21. , 22 are both fully opened. Point d shows the case where the first intake port 21 is fully opened and the second intake port 22 is half opened, and point e shows the case where both intake ports 21 and 22 are both half opened, and f
The points indicate the case where the first intake port 21 is half-open and the second intake port 22 is fully open. That is, the line from point b to point d to point c is the first helical port.
The case where the intake port 21 is fully opened is shown, and the line from point a to point f to point c shows the case where the second intake port 22, which is a tangential port, is fully opened, and points c, d, Region (g) surrounded by points e and f shows the case where both intake ports 21 and 22 are both half-open or more. In the embodiment of the present invention, opening / closing control of the intake ports 21 and 22 is performed so as to obtain a predetermined swirl ratio in each operation range (see FIGS. 5 and 6).

As shown in FIG. 5, in the embodiment of the present invention, the opening / closing control of each intake port 21, 22 is performed so that a predetermined swirl ratio can be obtained in each operation range. In the low load region (C), the first intake port 21 which is a helical port is fully closed and the second intake port 22 which is a tangential port is fully opened, that is, the on-off valve control at point a in FIG. By doing, a low swirl with a small swirl ratio is generated. In the medium load range (B), on-off valve control is performed so that both intake ports 21 and 22 are half open or more, that is, the on-off valve is in the (g) region surrounded by points c, d, e and f in FIG. By performing the control, a medium swirl having a medium swirl ratio is generated. In the high load region (A), opening / closing valve control is performed in which the first intake port 2 which is a helical port is fully opened and the second intake port 22 which is a tangential port is less than half open, that is, from point b to point d in FIG. A high swirl with a large swirl ratio is generated by performing on-off valve control at a predetermined point on the line.

Thus, in the low load range (C),
Only the second intake port 22, which is a tangential port having a small intake resistance, is fully opened to generate a low swirl. Therefore, since the intake resistance is reduced, the required intake charge amount can be secured, and the low swirl can improve the fuel consumption by increasing the combustion speed without leaning the fuel spray.

In the medium load range (B), since the on-off valves provided in both intake ports 21 and 22 are set to at least half open, intake resistance becomes small. Therefore, the required intake charge amount can be secured. Further, the moderate swirl improves the fuel property, and as a result, it is possible to prevent the fuel temperature from becoming high and to suppress the generation of nitrogen oxides. High load area (A)
In the first intake port 21 which is a helical port
High swirl with a large swirl ratio is generated by fully opening only. Therefore, while ensuring an appropriate intake charge amount, high swirl promotes mixing of fuel and air to improve combustion efficiency (air utilization rate), improve output, and generate black smoke (smoke). Can be suppressed.

As described above, according to this embodiment, it is possible to effectively reduce the intake resistance in the low-to-medium load region which is the practical operation region, and thereby to secure the required intake charge amount. Next, another embodiment of the present invention will be described with reference to FIG. In this embodiment, the on-off valves provided in the intake ports 21 and 22 are controlled so as to form the medium swirl region in the high engine speed region regardless of the load. That is, in the high speed region, both intake ports 2
Open / close valve control to make both 1 and 22 half open or more, that is, FIG.
By performing on-off valve control in the region (g) surrounded by the points c, d, e, and f, the medium swirl with a medium swirl ratio is generated.

In the high speed region, the swirl tends to be high because the speed of the intake air introduced into the cylinder is high. Therefore, in the present embodiment, even if the opening / closing valve control is performed so as to generate the medium swirl as described above, the high swirl can be generated as a result. Furthermore, in the high engine speed range, the intake valve opening time per engine revolution is short, but in the present embodiment, both intake ports 21, 22 are made half open or more to secure the intake charge amount. I have to.

According to this embodiment, an appropriate high swirl that avoids overswirl can be generated, so that the output can be improved and the generation of black smoke (smoke) can be suppressed. Further, in this embodiment, at the time of free accelerator or acceleration, as shown in FIG. 6, the high swirl region (A) is expanded to the medium load region to form the high swirl region (A ₁ ). That is, at the time of a free accelerator in which the accelerator is depressed in the neutral state (so-called idling of the accelerator) and at the time of acceleration, a rapid rise in rotation causes a rapid increase in rotation, thereby reducing intake air introduced into the cylinder. As a result, the fuel injection amount becomes extremely large relative to the intake air amount, and black smoke (smoke) is generated. Therefore, in this embodiment, by expanding the high swirl area (A) to the medium load area and forming the high swirl area (A ₁ ), the mixing of fuel and air is promoted, and black smoke (smoke) is generated. Is suppressed.

Similarly, even if the supercharging pressure has not risen to a predetermined value due to turbo lag during acceleration, the amount of fuel injection is extremely large relative to the amount of intake air, and black smoke (smoke) is generated. Also in this case, as shown in FIG. 6, the high swirl area (A) is expanded to the medium load area and the high swirl area (A ₁ )
By forming the, the same effect can be achieved.

In the present invention, the open / close valve 8 is used.
When the opening / closing control of 1, 82 is performed, the opening operation may be performed fast and the closing operation may be delayed, and the closing operation may be corrected so that the fuel injection amount is increased. The reason why the opening operation of the on-off valve is made faster is to improve the responsiveness. The reason why the closing operation of the on-off valve is delayed and the correction is performed so as to increase the fuel injection amount for the closing operation is as follows. That is, if the closing operation is performed quickly, the inside of the cylinder becomes a negative pressure, and it becomes difficult for the engine to rotate. In order to prevent this, the closing operation of the on-off valve is delayed,
Further, by increasing the fuel injection amount, the combustion pressure is increased, the engine speed is increased, and the negative pressure in the cylinder is offset.

[0031]

As described above, according to the intake system for a diesel engine of the present invention, it is possible to secure the intake charge amount by reducing the intake resistance and to form a good swirl according to the load. It is possible to suppress the generation of black smoke (smoke) by promoting the mixing of air with air.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an intake device of a direct injection diesel engine.

FIG. 2 is a vertical sectional view showing an engine to which an embodiment of the present invention is applied.

FIG. 3 is a plan view showing an intake port and an exhaust port of FIG.

FIG. 4 is a diagram showing the control contents of the on-off valve in each operating range indicated by the swirl ratio and the engine speed according to the embodiment of the present invention.

FIG. 5 is a diagram showing the control contents of the on-off valve in each operation range indicated by the engine load and the engine speed according to the embodiment of the present invention.

FIG. 6 is a diagram showing the control contents of the on-off valve in each operating range indicated by the engine load and the engine speed according to another embodiment of the present invention.

[Explanation of symbols]

 1 Engine 2 Cylinder 15 Combustion Chamber 16 Piston 21 First Intake Port 22 Second Intake Port 81 Opening / Closing Valve 82 Opening / Closing Valve 90 Controller 91 Unit Injector 92 Fuel Injection Pump

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mitsunori Kondo 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Motor Corporation

Claims (2)

[Claims] 1. A helically-shaped first intake port having an opening whose axial center extends in a tangential direction of the cylinder to strengthen a swirl of a horizontal component orthogonal to the cylinder axial center, and the axial center of the opening is the above-mentioned first intake port. A second intake port of a diesel engine having a tangential second intake port extending in the same direction as the port and directed in the cylinder axis direction from the first intake port to strengthen the swirl of the cylinder axial center component. A first on-off valve provided on the port, a second on-off valve provided on the second intake port, and a low-load region in which the first on-off valve is fully closed and the second on-off valve is fully open, In the medium load range, both the first and second open / close valves are half open or more, and in the high load range the first open / close valve is
An intake device for a diesel engine, comprising: a control unit that fully opens the on-off valve and sets the second on-off valve to less than half open. 2. A helically-shaped first intake port, in which the axial center of the opening extends in the tangential direction of the cylinder and strengthens the swirl of the horizontal component orthogonal to the cylinder axial center, and the axial center of the opening is the first intake port. A second intake port of a diesel engine having a tangential second intake port extending in the same direction as the port and directed in the cylinder axis direction from the first intake port to strengthen the swirl of the cylinder axial center component. A first opening / closing valve provided in the port, a second opening / closing valve provided in the second intake port, and a fully closed first opening / closing valve in the low load / low speed region. In the medium load range, the low load high rotation range, and the high load high rotation range, both the first opening / closing valve and the second opening / closing valve are half-opened or more, and in the high load low rotation range, the first opening / closing valve is fully opened. Second above An intake device for a diesel engine, comprising: a control means for opening and closing the valve to less than half open.