JPH073174B2 - Engine intake control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Field of Industrial Application The present invention provides two intake valve openings for one cylinder in an engine body, and each intake valve opening has a valve operating valve. The present invention relates to an intake control device for an engine in which intake valves that are opened and closed by a mechanism are provided.

(2) Conventional Technology Conventionally, such a device is known, for example, from Japanese Patent Laid-Open No. 56-56942.

(3) Problems to be Solved by the Invention In the above-described conventional art, the torque is improved by changing the number of actuations of the intake valve, the valve opening timing, and the lift amount according to the operating state of the engine. There is.

By the way, in the intake stroke of a 4-cycle engine, the air column in the intake passage is accelerated by the difference between the negative pressure and the atmospheric pressure generated in the cylinder, and the air column is inertial even if the piston passes through the bottom dead center in the cylinder. Due to this, the pressure flows into the cylinder, and the head changes to increase the suppression pressure each time, and the filling amount in the cylinder increases. This is well known as the inertia effect of the intake passage, and by setting the length of the intake passage in accordance with the operating characteristics of the intake valve, it is possible to increase the charging efficiency of the engine and thus the torque. Let's do it.

It is also known that swirl can be generated in the combustion chamber to improve the combustibility by allowing intake air to flow from only one of the pair of intake valve openings in the low speed operation range.

The present invention has been made in view of such circumstances, and it is possible to change the operating characteristic of the intake valve and the intake passage length according to the operating state of the engine, and to obtain the swirl effect in the low speed operation range. It is an object of the present invention to provide an intake control device having a simple structure that enables intake control adapted to a wide range from a low speed to a high speed operation range.

B. Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention has two cylinders.
In an intake control device for an engine, one intake valve opening is provided in the engine body, and each intake valve opening is provided with an intake valve that is driven to open and close by a valve operating mechanism. An intake passage is connected to the second intake valve port, and a high-speed intake passage is connected to the second intake valve port. In the low-speed operating range of the engine, the intake valve of the first intake valve port is opened and closed with operating characteristics corresponding to the low-speed operating range. , A valve operation change in which the intake valve of the second intake valve opening is stopped in a closed state, and the intake valves of the both intake valve openings are opened and closed with operating characteristics corresponding to the high speed operating range in the high speed operating range of the engine. A mechanism is provided in the valve mechanism, and the low-speed intake passage is provided with passage length changing means for changing the length thereof in the low-speed operation region to be long and in the high-speed operation region to be short.

(2) Action In the low speed operation range of the engine, the intake valve at the second intake valve opening state is deactivated and the intake air from the high speed intake passage is blocked, so that intake is possible only from the low speed intake passage,
Moreover, the length of the low-speed intake passage is set to be long so as to match the operating characteristics corresponding to the low-speed operation range of the intake valve that opens and closes the first intake valve opening, which improves the combustibility by the optimized swirl. At the same time, the low speed torque is increased.

On the other hand, in the high-speed operating range of the engine, the overall cross-sectional area of the intake passage is increased by the low-speed intake passage corresponding to the high-speed operating range and the high-speed intake passage corresponding to the high-speed operating range. Inhalation will be performed, and the first
Also, the operating characteristics of each intake valve of the second intake valve port are adapted to the high speed operation range, and the torque is increased in the high speed operation range.

(3) Embodiment Hereinafter, one embodiment of the present invention will be described with reference to the drawings. First, in FIG. 1 and FIG. 2, this engine is a fuel injection type multi-cylinder engine, and an engine body 1
For each cylinder CL, the first intake valve port H1 is connected to the first
An intake port P1 and a second intake port P2 connected to the second intake valve opening H2 are respectively provided, a first intake valve V1 is provided at the first intake valve opening H1, and a second intake valve opening H2 is provided at the second intake valve opening H2. A second intake valve V2 that also functions as an intake air cutoff unit is provided. Further, the engine body 1 is provided with a pair of exhaust ports (not shown) for each cylinder CL, and an exhaust valve is provided corresponding to each exhaust port. It operates similarly to the first and second intake valves V1 and V2, and hereinafter, only the intake system of the engine will be described in detail, and the detailed description of the exhaust system including the exhaust valve will be omitted.

Referring also to FIG. 3, the first and second intake valves V1 and V2 of each cylinder CL are spring-biased in the valve closing direction, that is, upward, and are pressed downward by the valve mechanism 2. Open the valve.

The valve mechanism 2 is a low speed cam C1 and a high speed cam C3 that are integrally provided on a cam shaft 3 that is rotationally driven at a speed reduction ratio of 1/2 according to the rotation of the engine. The first and second rotatably supported by a ridge C2 provided on the cam shaft 3 on the side opposite to the working cam C1 and a rocker shaft 4 fixedly arranged in parallel with the cam shaft 3.
And third rocker arms A1, A2, A3.

The low speed cam C1 is integrally provided on the cam shaft 3 at a position corresponding to the first intake valve V1, and the raised portion C2 is integrally provided on the cam shaft 3 at a position corresponding to the second intake valve V2.
Also, the high speed cam C3 is between the low speed cam C1 and the ridge C2,
That is, it is integrally provided on the camshaft 3 at a position corresponding to between the first and second intake valves V1, V2. Moreover, the low-speed cam C1 has a high portion with a relatively small amount of outward projection along the radial direction of the camshaft 3, and the bulge portion C2 is formed in a perfect circle concentric with the camshaft 3 for high speed. Cam C3 for
The camshaft 3 has a high-level portion in which the amount of protrusion outward in the radial direction and the center angle range are larger than the high-level portion of the low-speed cam C1.

The first and second rocker arms A1 and A2 are basically formed in the same shape, and swingably supported by the rocker shaft 4 so as to abut the upper ends of the first and second intake valves V1 and V2.
The third rocker arm A3 is the first and second rocker arm A.
The rocker shaft 4 is pivotally supported between 1 and A2. Moreover, the third rocker arm A3 is biased upward by a spring (not shown) so as to be constantly in sliding contact with the high speed cam C3.

When the operating oil pressure is supplied to such a valve mechanism 2 through an oil passage 5 provided in the rocker shaft 4, the first
-Valve operation changing mechanism 6 configured to integrally connect the third rocker arms A1 to A3 and enable relative angular displacement of the first to third rocker arms A1 to A3 when the operating oil pressure is released.
Is attached. When the valve operation changing mechanism 6 integrally connects the first to third rocker arms A1 to A3,
As the third rocker arm A3 swings by the high speed cam C3, the first and second rocker arms A1 and A2 swing,
The first and second intake valves V1, V2 are opened and closed at the timing and lift amount according to the shape of the high speed cam 3. Further, when the valve operation changing mechanism 6 is in a state in which the relative angular displacement of the rocker arms A1 to A3 shown in FIGS.
The first rocker arm A1 swings in response to the rotation of C1, and the first intake valve V1 opens and closes at the timing and lift amount corresponding to the shape of the low speed cam C1. At this time, the second rocker arm A2
Remains in sliding contact with the raised portion C2 and does not swing, and the second intake valve V2 remains closed until it is closed.

In the middle of the pipe line 8 connecting the oil passage 5 and the hydraulic pressure supply source 7,
An electromagnetic switching valve 9 is provided for switching between a state in which the operating oil pressure from the oil pressure supply source 7 is supplied to the valve operation changing mechanism 6 and a state in which the oil pressure in the valve operation changing mechanism 6 is released. This solenoid operated directional control valve 9 has a state in which the hydraulic pressure of the valve operation changing mechanism 6 is released when the engine speed is in a low speed operation range below a predetermined first set speed N1 and the engine speed is the first set speed. It is possible to switch between a state in which the operating oil pressure is supplied to the valve operation changing mechanism 6 in the high-speed operation range exceeding several N1.

The pair of exhaust valves of each cylinder CL are also provided with the same valve operating mechanism 2 and valve operation changing mechanism 6 associated with both intake valves V1 and V2.

Therefore, when the engine is in the low speed operation range below the first set speed N1, only the first intake valve V1 and one exhaust valve are opened and closed, and in the high speed operation range where the first set speed N1 is exceeded, both intake valves V1 , V2 and both exhaust valves open and close. Moreover, the opening and closing timings of the intake valves V1, V2 and the exhaust valve and the lift amount are different between the low speed operation range and the high speed operation range, and the shapes of the low speed cam C1 and the high speed cam C3 that regulate the timing and the lift amount are different for each operation. Each is set to improve the torque in the range.

The first intake port P1 of each cylinder CL in the engine body 1 is connected to a first intake pipe 10 for forming a low speed intake passage WL in cooperation with the intake port P1 and a second intake port P2. A second intake pipe 11 for forming a high-speed intake passage WH in cooperation with the intake port P2 is connected to each. Moreover, the first and second intake pipes 10 and 11 of each cylinder CL are
It is commonly connected to an air chamber 12 extending long in the cylinder arrangement direction of the engine body 1.

A plurality of connection ports 13 are provided in the lower side surface of the air chamber 12 on the engine body 1 side, and a second intake pipe corresponding to each cylinder CL is provided.
11 are connected to the connection ports 13, respectively. Also, the first intake pipe 10
Is an intake pipe portion 14 formed integrally with the second intake pipe 11,
The air chamber 12 and an intake pipe portion 15 which are integrally provided are connected to each other. One of the intake pipe portions 15 is arranged so that the connection port 17 is located below the connection port 13 from the outlet 16 which is opened on the side surface of the air chamber 12 opposite to the engine body 1 and through the bottom of the air chamber 12. The intake pipe portion 14 is formed and is connected to the connection port 17.

Referring also to FIG. 4, at the bottom of the air chamber 12,
Opening so that it can communicate with one of the intake pipe parts 15
18 are provided. In the low speed intake passage WL, the length from the opening 18 to the first intake port P1 via the intake pipe portion 14 is from the connection port 13 to the second intake pipe 11 to the second intake port P2. It is set to be almost the same as the length of the high-speed intake passage WH.

In the middle of the low speed intake passage WL, that is, in the middle of the intake pipe portion 15 of the first intake pipe 10, only the opening 18 is provided in the first intake port.
The state where it communicates with P1 and only the outlet 16 is the first intake port
Passage length changing means 19 is provided for changing the length of the low speed intake passage WL by switching between the state of communicating with P1.
This passage length changing means 19 is provided with an opening 18 in the middle of the suction pipe 15.
And the switching valve 20 arranged at the position corresponding to
And an actuator 21 for driving the.

In FIG. 5, the switching valve 20 is configured by connecting a plurality of valve bodies 22 arranged corresponding to the respective openings 18 with a common drive rod 23. The valve body 22 includes a pair of circular plates 24, 24 that closes the edges of the circular plates 24, 24.
The cross section of the closing plate 25 is formed in a half moon shape. Each valve body 22 is rotatably supported by arcuate support portions 27 formed on the upper and lower surfaces of the intake pipe portion 15 at positions corresponding to the openings 18, and the closing plate 26 covers the openings 18 in FIG. It is possible to close the valve body 22 by 90 degrees from that state, and to close the outlet 16 side of the intake pipe portion 15 as shown in FIG.

The actuator 21 is, for example, a rotary solenoid, and the drive rod 23 is connected to the actuator 21. Moreover, the actuator 21 has a second engine speed N2 (for example, N2 <N) in which the engine speed is different from the first engine speed N1.
1) When in the low speed operation range below
In the high-speed operation range in which it operates so as to block the second set speed N2, the opening 18 is opened to open the outlet as shown in FIG.
It operates so as to close the 16 side with the valve body 22.

Therefore, the length of the low-speed intake passage WL is
When in the low speed operation range below the set speed N2, the outlet 16
From the opening 18 to the first intake port P1 when the engine enters the high speed operation range where the engine speed exceeds the second set speed N2. And the length is almost the same.

A fuel injection valve VF is disposed in the middle of the intake pipe portion 14 of each first intake pipe 10 toward the first intake port P1, and the fuel injection valve VF is connected to the first intake port corresponding to the operating state of the engine.
Fuel is injected into P1.

Next, the operation of this embodiment will be described. First, when the engine is in the low speed operation range of the second set rotational speed N2 or less, the length of the low speed intake passage WL is increased by the passage length changing means 19, so The torque is improved by increasing the inertia effect. In addition, the engine has a first set speed different from the second set speed N2.
When in the low speed operation range equal to or lower than the set rotational speed N1, the valve operation changing mechanism 6 suspends the operation of the second intake valve V2, and only the first intake valve V1 is opened and closed. At this time, the torque is further improved by setting the opening / closing timing of the first intake valve V1 and the lift amount so as to correspond to the low speed operation range.
Moreover, the swirl can be effectively generated in the combustion chamber by the intake air from only the first intake valve port H1, and the combustibility can be improved. That is, in the low speed operation range, the time from the end of the intake stroke to the compression and combustion stroke is longer than in the high speed operation range, and it is necessary to effectively generate swirl for a relatively long time. Intake valve
The length of the low speed intake passage WL connected to H1 is the passage length changing means 19
Since it has been changed for a long time to correspond to the low speed operation range,
The swirl can be effectively generated in the combustion chamber.

When the engine enters the high speed operation range exceeding the second set speed N2, the passage length changing means 19 causes the low speed intake passage WL to operate.
The length of is shortened to almost the same length as the high-speed intake passage WH, and its length is set to an appropriate length corresponding to the high-speed operating range. The torque can be improved. Furthermore, the engine is the first
When entering a high speed operation range exceeding the set speed N1, the rocker arms A1 to A3 are connected by the valve operation changing mechanism 6 and both the first and second intake valves V1 and V2 correspond to the shape of the high speed cam C3. A high output can be obtained by opening and closing at the timing and lift amount.

The output P and torque T of the engine due to such an action
FIG. 7 shows the effect on the graph. In FIG. 7, AT, BT, CT show torque characteristics, AP, BP,
CP indicates the output characteristic.

As is apparent from FIG. 7, the output P is the second
The output characteristics are switched depending on the set rotational speed N2 and the first set rotational speed N1, and the output can be improved especially in a high-speed operation range exceeding the first set rotational speed N1. Further, regarding the torque T, the operating range below the second set speed N2, the second set speed N2
Over the first set speed N1 or less and the operating range over the first set speed N1 to have respective peaks and control the drop of the torque T as much as possible to operate from the low speed range to the high speed range. The torque can be improved in a wide driving range over a range.

In the above embodiment, the first set speed N1> the second set speed N1.
Although N2 is set, it may be set such that the second set rotation speed N2> the first set rotation speed N1.

C. Effects of the Invention As described above, according to the present invention, in the low speed operation range of the engine, intake air from the high speed intake passage is blocked by the intake valve of the second intake valve opening connected to the high speed intake passage. Intake is performed only from the low-speed intake passage, and the operation characteristics of the intake valve of the first intake valve opening connected to the low-speed intake passage correspond to the low-speed operating range, and the low-speed intake passage conforms to the low-speed operating range. Since it is as long as possible, it is possible to effectively generate swirl in the combustion chamber to improve the combustibility and increase the low speed torque.

On the other hand, in the high-speed operating range of the engine, the overall cross-sectional area of the intake passage is increased by the low-speed intake passage corresponding to the high-speed operating range and the high-speed intake passage corresponding to the high-speed operating range. Inhalation will be performed, and the first
In addition to the fact that the operating characteristics of each intake valve of the second intake valve opening are adapted to the high speed operation range, it is possible to increase the torque in the high speed operation range. It is possible to increase the torque over a wide operating range.

[Brief description of drawings]

The drawings show an embodiment of the present invention. Fig. 1 is a plan view of a main part, Fig. 2 is a sectional view taken along the line II-II of Fig. 1, and Fig. 3 is an enlarged view of an arrow III of Fig. 2. Fig. 4 is a sectional view taken along the line IV-IV in Fig. 1, Fig. 5 is a perspective view of a switching valve, and Fig. 6 is a sectional view corresponding to Fig. 2 for showing a state in which a passage length changing means is operated. Figure,
FIG. 7 is an engine output characteristic diagram. 1 ... Engine body, 2 ... Valve mechanism, 6 ... Valve operation changing mechanism, 19 ... Passage length changing means, CL ... Cylinder, H1 ... First intake valve port, H2 ... Second intake valve Mouth, V1, V2 ... Intake valve, W
H: High speed intake passage, WL: Low speed intake passage

Claims (2)

[Claims] Claims: 1. Two intake valve openings (H) for one cylinder (CL)
1, H2) is provided in the engine body (1), and intake valves (V1, V2) that are driven to open and close by the valve operating mechanism (2) are provided at the intake valve openings (H1, H2), respectively. In the engine intake control device, a low speed intake passage (WL) is connected to the first intake valve opening (H1), and a high speed intake passage (WH) is connected to the second intake valve opening (H2). In the low speed operation range, the intake valve (V1) of the first intake valve opening (H1) is opened and closed with operating characteristics corresponding to the low speed operation range, while the intake valve (V2) of the second intake valve opening (H2) is opened and closed. Shuts down the valve in the closed state, and changes the valve operation to open and close the intake valves (V1, V2) of both intake valve ports (H1, H2) in the high speed operation range of the engine with the operation characteristics corresponding to the high speed operation range. The mechanism (6) is the valve mechanism (2).
The intake passage for low speed (WL) is provided with passage length changing means (19) for changing the length of the low speed intake passage (WL) to be long in the low speed operation range and short in the high speed operation range. Control device. 2. A first engine speed set to operate the valve operation changing mechanism (6) and a second engine speed set to operate the passage length changing means (19) mutually. The intake control device for the engine according to claim (1), wherein the intake control device is set differently.