JPH0340238B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-intake valve type internal combustion engine having two intake valves for each cylinder, and particularly to an intake system thereof.

A two-intake valve internal combustion engine has two intake valves for each cylinder's combustion chamber.
Both intake valves are connected to a surge tank through respective intake passages.
On one side of the intake passage, there is an intake control valve that closes when the amount of intake air is small (during partial load or high load and low speed) and opens when the amount of intake air is large (during high load and high speed). is provided, which improves output torque at partial loads, high loads, and low rotational speeds (increases combustion speed by increasing intake air flow velocity and increases volumetric efficiency by utilizing the intake inertia effect), and improves output torque at high loads and high rotational speeds. This simultaneously improves the volumetric efficiency of intake air.

In other words, in such a two-intake valve type internal combustion engine, when the control valve is opened during high-load, high-speed operation, the rotation speed that generates the maximum torque is on the extremely high rotation speed side, but when the control valve is closed, This causes the rotational speed that generates maximum torque to shift toward the middle speed range. It has been found that this change in the torque characteristic curve due to the opening and closing of the control valve occurs only when the intake passages are interconnected in the vicinity of the intake valve. That is, when the intake passages are completely independent and separated from each other, the torque characteristics do not change even if the control valve is opened or closed. For this purpose, a merging section is usually provided in the intake passage near the intake valve.

It is known that torque in the middle and low speed ranges can be recovered by controlling the intake air by controlling the opening and closing of the intake control valve in this manner.

On the other hand, as a means to achieve stable lean combustion in the partial load range, the combustion chamber is stratified by generating an intake swirl and then injecting fuel into the intake port in the latter half of the intake stroke. There are known ways to do this.

Until now, there has been no two-intake valve internal combustion engine designed to recover torque in the low-speed range under high loads (full load) as described above, and in fact, there has been no one that incorporates the concept of stable lean combustion in the partial load range. It was not possible to satisfy both demands.

The present invention uses a special intake control valve device developed by the present invention in a two-intake valve type internal combustion engine, which has the original purpose of improving torque at low speeds under high loads by using a special intake control valve device. Therefore, it is an object of the present invention to provide an intake system that can meet the requirements for stable lean combustion in a partial load range.

This will be explained below with reference to the attached drawings.

In FIG. 1, a combustion chamber 15 formed in a cylinder head 8 is provided with two intake valves 3a, 3b and two exhaust valves 10a, 10b. Each intake valve 3a, 3b is connected to a respective intake passage 2 of the intake pipe 14.
It is connected to a surge tank (not shown) via a and 2b. The intake passages 2a and 2b are separated by a partition wall 6, but there is a confluence part 5 near the intake valve.
communication is established. The fuel injection valve 4 is attached to the intake pipe 14 so that its injection direction is directed toward the center of both intake valves at the merging portion.

Note that 11 represents a spark plug, and 13 represents an exhaust pipe.

An intake control valve 27 is provided in one of the intake passages, for example 2b. This intake control valve 27 constitutes the intake control valve device of the present invention, but before explaining the special control mode of the present invention, the general control mode and function of the intake control valve 27 will be explained.

The control valve 27 is generally closed when the amount of intake air is small, such as during high load or low rotation (corresponding to the second position shown in Figure 1b), and increases the intake flow velocity by narrowing the intake passage area. This increases the combustion speed and improves the shaft torque at low and medium speeds due to the intake inertia effect. On the other hand, the control valve 27 is opened when the amount of intake air is large, such as when the load is high and the rotation speed is high (corresponding to the third position shown in FIG. 1c) to maximize the area of the intake passage and increase the volumetric efficiency. .

Figure 7 shows engine speed N and shaft torque (output) Te
FIG. 2 is a general torque characteristic diagram showing the relationship between
When the control valve 27 is fully opened, generally A ₁ in Fig. 7
The shaft torque shown in is obtained. As shown by _A1 , the shaft torque takes a maximum value when the rotational speed N is _N0 (N= _N0 ), but generally _N0 is a large value of 5000 rpm or more. When two intake valves 3a and 3b are provided as shown in Fig. 1, the maximum shaft torque value is also considerably large, resulting in a so-called "fast-running engine," but on the other hand, the shaft torque in the middle and low rotation ranges is In fact, it becomes even lower than when there is only one intake valve, which is even less desirable during normal driving. Therefore, in such a state, control valve 2
7 to the second position to narrow down the intake passage area, it has been found that the torque characteristic curve becomes as shown by _A2 in FIG. That is, N that gives the maximum shaft torque shifts from N ₀ to N ₁ on the low rotation speed side. This is because the equivalent length of the intake pipe is increased by controlling the intake control valve 27 to the second position.

Therefore, by controlling the opening/closing of the intake control valve 27 so as to close it at a predetermined rotational speed N _S , the mid-speed or low-speed shaft torque under full load can be recovered and improved.

In the conventional two-intake valve type internal combustion engine as described above, the present invention further aims to enable good lean burn or high-volume EGR at partial load (corresponding to the area indicated by A ₃ in Figure 7). It is something to do. In conventional technologies that do not have the purpose of achieving lean burn during such partial loads, the intake control valve 27 is generally disposed on the upstream side of the merging section 5 (the side far from the combustion chamber), and is fully closed and fully open. It only occupies two valve positions. In contrast, in the present invention, the intake control valve 27 occupies three valve positions. That is, a first position (corresponding to FIG. 1a) in which the air-fuel mixture is introduced into the combustion chamber only from the first intake valve 3a by blocking the intake passage from the merging portion 5 to one of the intake valves, for example, the second intake valve 3b. ), the second intake passage 2b is closed and the second intake valve 3 is opened from the confluence part 5.
Open the intake passage leading to b and open the first and second intake valves 3.
A second position (corresponding to FIG. 1 b) where the mixture is introduced from both the first and second intake valves 3a and 3b, and a second position where the mixture is introduced from both the first and second intake valves 3a and 3b by opening the second intake passage. Three types of positions can be taken: the third position (corresponding to FIG. 1c). The second position and the third position correspond to the conventional intake control valve fully closed position and fully open position, respectively. Therefore, it can be said that the present invention has a first position control mode added to the prior art. Furthermore, in the three positions mentioned above, in the first position, the function of the second intake valve is disabled and the function of the second intake passage is effective, and in the second position, the function of the second intake passage is disabled and the function of the second intake passage is valid. The function of the 2nd intake valve is effective, and in the 3rd position, the 2nd intake valve,
In other words, the second intake passages are both effective. Note that the first intake valve and the first intake passage are always effective.

As mentioned above, the intake control valve 27 is set to the third position during high load and high rotation, and to the second position during high load and low rotation.
This position ensures high output torque during high loads, and at the same time, it assumes the first position during partial loads to ensure lean burn or mass EGR. In the first position, air from the second intake vent 2b is introduced into the combustion chamber from the first intake valve 3a via the confluence section 5, but its direction is bent when passing through the confluence section 5. Therefore, the injected fuel 12 from the fuel injection valve 4 is bent as shown in FIG.
A strong swirl is applied to the air-fuel mixture sucked into the combustion chamber 15 from the first intake valve 3a as shown by the arrow. Apart from this, it is also possible to make the first intake passage 2a a helical port in order to generate intake swirl more actively. In this way, the generation of intake swirl, which is a prerequisite for lean burn due to stratification of the air-fuel mixture, is ensured. Furthermore, in order to cause stratification of the air-fuel mixture, the fuel injection start timing may be controlled in accordance with the engine speed and load so that all of the injected fuel is drawn into the combustion chamber in the latter half of the intake stroke. It is known that by controlling in this way, the area around the spark plug 11 becomes rich and the area around the piston (not shown) becomes lean, thereby stratifying the air-fuel mixture. Due to this stratification, as shown in FIG. 8, the lean limit air-fuel ratio A/F for combustion is higher than that in the conventional case (indicated by a broken line) when fuel is injected at the same time as ignition (indicated by a broken line). It is possible to achieve a lean value of 3 to 5 and obtain good fuel efficiency and exhaust emissions.

Various arrangements for allowing the intake control valve 27 to assume the above-mentioned three positions are shown in FIGS. 1 to 6. In each figure, a indicates the first position, b the second position, and c the third position, respectively. Also, in any of the figures, part reference numbers are shown only in figure a,
Figures b and c are omitted for clarity. Common parts in each figure are indicated by the same numbers and explanations will be omitted.

In FIG. 1, a support shaft 26 that rotatably supports the control valve 27 is provided approximately at the center of the merging portion 5 and at the center of the second intake passage 2b. In the first position, the control valve 27 has its upper end edge in contact with the partition wall 6 downstream of the merging portion, and its lower end wall in contact with the inner wall of the intake pipe on the second intake passage side a. Also, in the second position, the control valve 2
The upper edge of 7 contacts the inner wall of the intake pipe on the second intake passage side, and the lower edge of 7 contacts the partition wall 6 upstream of the merging portion.

In FIG. 2, the support shaft 26 is provided on the inner wall of the intake pipe 14 on the second intake passage side at a position corresponding to approximately the center of the merging portion 5, and the control valve 27 is a single-open valve plate.

In FIG. 3, the control valve device is composed of two first and second control valves 27a and 27b, one of which 27a is connected to the second intake passage 2 downstream of the confluence section 5.
b, and the other control valve 27b is provided in the confluence part 5.
It is provided in the second intake passage 2b upstream of the intake passage 2b. When the second intake control valve 27b is in its first position (FIG. 3a), almost the same effect can be obtained even when it is in the closed position as shown by the imaginary line. This is because the intake swirl itself is generated due to the shape of the combustion chamber itself even if only the intake air is from the first intake passage 2a.

Also in FIG. 4, two intake control valves 27a, 2
7b is provided, the support shaft 26a of the first control valve 27a is attached to the end of the partition wall 6 on the upstream side of the confluence section 5, and the support shaft 26b of the second control valve 27b is attached to the end of the partition wall 6 on the upstream side of the confluence section 5. 2 is provided in the intake passage 2b.
Further, in FIG. 4, the fuel injection valve 4 is provided in the first intake passage 2a near the merging portion 5. Of course, in carrying out the present invention, it is possible to arrange the fuel injection valve 4 in this way, but it is inferior to the arrangement shown in Figs. 1 to 3, especially in terms of uniform mixing of the air-fuel mixture in the third position. Would.

FIG. 5 is almost the same as the embodiment shown in FIG. 4, but
The second control valve 27b is connected to a second control valve downstream of the merging section 5.
The only difference from FIG. 4 is that it is disposed within the intake passage.

FIG. 6 shows an embodiment in which the first and second control valves 27a and 27b are attached to a common support shaft 26 provided at the end of the partition wall 6 on the upstream side of the confluence section. The second control valve 27b is in charge of opening and closing control of the second intake passage 2b.

It will be easily understood that in each of the embodiments described above, each control valve device can selectively assume any of the three positions described above.

It will also be understood that the same effect can be obtained even if the control valve device is provided on the first intake passage side, contrary to the illustrated embodiments.

FIG. 9 is a cross-sectional illustrative view showing an example of the actuator of the control valve 27, taking the embodiment of FIG. 1 as an example.

The intake control valve 27 is fixed to the valve lever 34 via the support shaft 26. The valve lever 34 is connected to the rod 35 through an elongated hole 36, and rotates together with the support shaft 26 around the support shaft 26 as the rod 35 moves in the longitudinal direction. It is rotated in a clockwise direction, thus controlling the three states a, b, and c in FIG. 1. The rod 35 is secured to a first diaphragm 41 of a diaphragm device 40. Diaphragm chambers 47, 48 partitioned by second diaphragm 42 are selectively connected to the atmosphere or a negative pressure region via respective negative pressure switching valves (VSV) 44, 45.
VSV44, 45 are each electrical control unit ECU50
Turns on and off according to the engine speed signal S _N and load signal _L input to the ECU 50 by a control signal from
Controlled off. S _N and S _L can each be detected by a known sensor (actually, for example, an intake negative pressure signal is used for S _L ).

First, when occupying the first position during partial load, the first VSV 44 is switched to the atmosphere side, and the second VSV 45 is switched to the negative pressure side. As a result, atmospheric air acts on the first diaphragm chamber (auxiliary diaphragm chamber) 47, negative pressure acts on the second diaphragm chamber (main diaphragm chamber) 48, and the rod 35 is moved by the second diaphragm 42 to the right side in FIG. The control valve 27 is pulled a full stroke in the direction shown in FIG. In this case, negative pressure may be applied to the first diaphragm chamber 47.

Then, during full load and low rotation, the first VSV44,
The second VSV 45 are both brought into communication with the atmosphere, so that the rod 35 is pushed back to the left in FIG. 9 by the first spring 43, bringing the control valve 27 into the second position of FIG. 1b.

At full load and high rotation, the 1st VSV44 is on the negative pressure side,
The second VSVs 45 are respectively communicated with the atmosphere. As a result, negative pressure acts on the first diaphragm chamber 47 and the atmosphere acts on the second diaphragm chamber 48, and the rod 35 is pulled to the right by the effective stroke G in the sub-diaphragm chamber 47, and the control valve 2
7 to the third position in FIG. 1c.

As described above, according to the present invention, it is possible to improve combustion by improving the intake swirl at partial load while improving the output torque throughout the high rotation range, middle and low rotation range at full load. Stable lean combustion can be achieved by stratifying the intake air indoors.

[Brief explanation of the drawing]

Figures 1a, b, and c are cross-sectional illustrative views showing the intake control valve of the intake device according to the present invention in three different positions;
Figures 2 a, b, c to 6 a, b, c are views similar to Figure 1 a, b, c showing five different embodiments from Figure 1 a, b, c; Fig. 7 is a torque characteristic diagram for a general two-intake valve type internal combustion engine, Fig. 8 is an air-fuel ratio diagram showing the lean burn effect of the present invention in comparison with the conventional technology, and Fig. 9 is a diagram of Fig. 1a. , b, and c are main part sectional illustrations showing an example of the actuator of the intake control valve. 2a, 2b...Intake passage, 3a, 3b...Intake valve, 4...Fuel injection valve, 5...Merge portion, 27...
Intake control valve.

Claims (1)

[Claims] 1. Each cylinder has two intake valves (first and second intake valves) and two independent intake passages (first and second intake passages) communicating with these intake valves. However, in a two-intake valve type internal combustion engine, these first and second intake passages are communicated with each other by a confluence section formed near the intake valve, and a fuel injection valve is provided at or near the confluence section. In the second intake passage, the air-fuel mixture is introduced only from the first intake valve by closing the second intake passage and blocking the intake passage from the merging part to the second intake valve, depending on the engine speed and load. the first position where the second intake passage is closed and the intake passage from the merging portion to the second intake valve is opened and the first and second intake passages are closed.
a second position for introducing the air-fuel mixture from both sides of the intake valve;
An intake control valve device is provided that selectively occupies a third position in which the second intake passage is opened and air-fuel mixture is introduced from both the first and second intake passages through both the first and second intake valves. An intake system for a two-intake valve internal combustion engine, characterized in that: 2. Claim 1, wherein the intake control valve device is constituted by a single control valve that is rotatable around a support shaft located at the center of the second intake passage near the center of the merging portion. Intake device as described in section. 3. Claim 1, wherein the intake control valve device is constituted by a single control valve that is rotatable around a support shaft attached to the inner circumferential wall of the second intake passage near the center of the merging portion. Intake device as described in section. 4. The intake valve control device includes a first control valve that is rotatable about a support shaft located downstream of the merging portion and located at the center of the second intake passage, and a first control valve that is rotatable about a support shaft that is located at the center of the second intake passage upstream of the merging portion. 2. The intake device according to claim 1, further comprising a second control valve rotatable about a support shaft. 5 The above-mentioned intake valve control device includes a first control valve that is rotatable about a support shaft disposed within the confluence section at the upstream end of the confluence section, and a second control valve that is rotatable about a support shaft disposed in the confluence section at the upstream end of the confluence section.
2. The intake device according to claim 1, further comprising a second control valve rotatable about a support shaft disposed at the center of the intake passage. 6 The above-mentioned intake valve control device includes a first control valve that is rotatable about a support shaft disposed within the confluence section at the upstream end of the confluence section, and a second control valve that is rotatable about a support shaft disposed in the confluence section at the upstream end of the confluence section.
2. The intake device according to claim 1, further comprising a second control valve rotatable about a support shaft disposed at the center of the intake passage. 7. The above-mentioned intake control valve device is constituted by first and second control valves that are rotatable about a common support shaft disposed within the merging portion at an upstream end of the merging portion. The intake device according to scope 1.