JPH02267320A - Intake device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve combustibility especially at the time of low speed operation in a device constructed in such a way as to have the varied action state of two intake valves according to high speed or low speed operation by providing it with a swirl creating intake port communicated with a first intake valve nozzle and an approximately rectilinear main intake port communicated with a second intake valve nozzle. CONSTITUTION:Each cylinder 2 is provided with a first and a second intake valves 12a, 12b for opening/closing a first and a second intake valve nozzles 6a, 6b, and at the time of low speed operation, only the first intake valve 12a is opened/closed by the rotation of a low speed cam 22 on a camshaft 2 through a first driving locker arm 26. At the time of high speed operation, however, both intake valves 12a, 12b are opened/closed by the rotation of a high speed cam 23 through the first and second driving locker arms 26, 28 integrally connected by a hydraulic connecting/switching means 29. A spiral swirl creating intake port 8 communicated with the first intake valve nozzle 6a and a rectilinear main intake port 9 communicated with the second intake valve nozzle 6b are further formed at a cylinder head 3.

Description

Detailed Description of the Invention A6 Object of the Invention (1) Industrial Field of Application The present invention provides first and second intake valve ports which are provided in an engine body facing a combustion chamber and which can be opened and closed. The present invention relates to an intake system for an internal combustion engine, in which an intake valve is disposed in an engine body, and a valve operating system that can change the operating state between low-speed operation and high-speed operation of the engine is connected to the first and second intake valves.

(2) Prior Art Conventionally, such a device has been disclosed in Japanese Patent Application Laid-Open No. 61-25283, for example.
It is publicly known from Publication No. 2 and the like.

(3) Problems to be Solved by the Invention By the way, in the above-mentioned conventional system, when the engine is operating at low speed, both intake valves are operated in an operating mode corresponding to low-speed operation, and the intake passage area is reduced by a swirl control valve to create a swirl effect. This reduces fuel consumption during low-speed operation, and when the engine is running at high speed, both intake valves are operated in a manner compatible with high-speed operation, and the area of the intake passage is enlarged with a swirl control valve to improve charging efficiency. We are trying to increase output.

However, in the above-mentioned conventional engine, during low-speed operation, the swirl control valve blocks the intake port leading to one intake valve port, and the air-fuel mixture is introduced into the combustion chamber only from the other intake valve port, thereby producing a swirl effect. However, the intake valve, which can open and close one intake valve port, opens and closes in an operating mode that corresponds to low-speed operation, and when one intake valve port leading to the combustion chamber opens and closes like that, it creates a swirl in the combustion chamber. will be disturbed. Moreover, since the one intake valve, which is not substantially involved in controlling the intake of the air-fuel mixture into the combustion chamber, is opened and closed, the driving force increases accordingly. Furthermore, in the above-mentioned conventional engine, it is necessary to provide a swirl control valve at the intake port, and during high-speed operation, the swirl control valve increases intake resistance, which becomes an impediment to improving output.

The present invention has been made in view of the above circumstances, and aims to reduce driving force while avoiding adverse effects on swirl generation in the combustion chamber during low-speed operation, and also makes it possible to reduce intake resistance during high-speed operation. The object of the present invention is to provide an intake system for an internal combustion engine.

B9 Structure of the Invention (1) Means for Solving the Problems According to the present invention, the engine body includes a spiral-shaped intake port for generating a swirl that communicates with the first intake valve port, and a substantially linear intake port that communicates with the first intake valve port. A main intake port communicating with the intake valve port is provided, and the valve operating device operates the first intake valve in an operating mode corresponding to low-speed operation while the second intake valve is at rest or almost at rest during low-speed engine operation. , when the engine is running at high speed
and a state in which the second intake valve is operated in an operating mode corresponding to high-speed operation.

(2) Effect According to the above configuration, when the engine is operating at low speed, the second intake valve is at rest or almost at rest, and the first intake valve is opened and closed in an operating mode corresponding to low speed operation, so that the swirl-generating intake port is The air-fuel mixture is introduced into the combustion chamber through the first intake valve port while swirling at a relatively high speed.At this time, since the second intake valve is almost at rest, there is no adverse effect on swirl generation in the combustion chamber. Instead, the driving force is reduced by the amount by which the second intake valve is deactivated. In addition, when the engine is operating at high speed, the first and second intake valves open and close in an operating mode that corresponds to high-speed operation. A large amount of air-fuel mixture is introduced, and there is nothing at each intake port that increases intake resistance.

(3) Example Hereinafter, an example of the present invention will be explained with reference to the drawings. First, in FIGS. 1 and 2, this vehicle-mounted D
In an OHC type multi-cylinder internal combustion engine, a plurality of cylinders 2 are arranged in series in a cylinder block 1, and the engine body E
A combustion chamber 5 is defined between a cylinder head 3 that is coupled to the upper end of the cylinder block 1 to constitute a combustion chamber, and a piston 4 that is slidably fitted into each cylinder 2.

Further, in the cylinder head 3, first and second intake valves 6a are provided in a portion forming the ceiling surface of each combustion chamber 5.

6b and first and second exhaust valve lowers a, 7b are provided. On the other hand, the cylinder head 3 is provided with a swirl-generating intake port 8 and a main intake port 9, both of which are opened on one side of the cylinder head 3 and have a common opening end. The port 8 is spirally curved and connected to the first intake valve 6a, and the main intake port 9 extends substantially linearly and connected to the second intake valve 6b. Further, the first and second exhaust valve lowers a, 7b are connected to a substantially straight exhaust port 10.11, and both exhaust ports 10.11
are commonly opened on the other side of the cylinder head 3.

In the part of the cylinder head 3 corresponding to each cylinder 2,
First and second intake valves 12a that can open and close the first and second intake valve ports 6a and 6b, respectively.

12b, and first and second exhaust valves 13a that can open and close the first and second exhaust valve lowers a and 7b, respectively.

13b, two sets of guide tubes 14 and 13b are provided.
... are fitted and fixed, respectively, and the intake valves 12a, 12 protrude upward from their guide tubes 14...
Valve springs 16 are contracted between the cylinder head 3 and the flange portions 15 provided at the upper ends of the exhaust valves 13a and 13b, respectively, and these valve springs 16... As a result, each intake valve 12a, 12b and each exhaust valve 13a, 13b are urged upward, that is, in the valve closing direction.

Each intake valve 12a, 12b is provided with an intake valve-side valve operating device 19 to be operated in an operating mode according to the operating state of the engine.
An exhaust valve side valve operating device 20 is connected to each exhaust valve 13a, 13b so as to be operated in an operating mode according to the operating state of the engine.

Referring to FIGS. 3 and 4 together, the intake valve side valve operating device 19 includes a camshaft 21 that is rotatably driven by a crankshaft (not shown) of the engine at a reduction ratio of 1/2, and a cam. A low speed cam 22 and a high speed cam 23 provided on the shaft 21
and a resting cam 24, a rocker shaft 25 fixedly arranged in parallel with the camshaft 21, a first drive rocker arm 26, a free rocker arm 27, and a second drive rocker arm 28, which are pivotally supported by the rocker shaft 25.
A hydraulic connection switching means 29 is provided between each rocker arm 26, 27, 28.

On the camshaft 21, a low speed cam 22 is located at a position corresponding to the first intake valve 12a, a stop cam 24 is located at a position corresponding to the second intake valve 12b, and a high speed cam 23 is located between both cams 22,24. Each is integrated. The low-speed cam 22 has a shape suitable for low-speed operation of the engine, and includes a base interior 22a and a high portion 22b protruding radially outward from the base interior 22a. Also, high speed cam 2
No. 3 has a shape suitable for high-speed operation of the engine, and includes a base interior 23a and a high portion 23b that protrudes from the base interior 23a with a larger protrusion amount and center angle range than the high portion 22b. Furthermore, pause cam 2
4 has a base interior 24a and a high portion 24b slightly protruding radially outward from the base interior 24a, and the high portion 24b can determine that the second intake valve 12b is substantially at rest. It protrudes from the inside of the base 24a at a position corresponding to the high part 22b of the low speed cam 22 and the high part 23b of the high speed cam 23, so as to have a protrusion amount and center angle range that slightly open the valve. be done.

On the other hand, the opening/linkage foot 25 is fixedly held on the cylinder head 3 at a position below the camshaft 21 and having an axis parallel to the camshaft 21. The rocker shaft 25 includes a first drive rocker arm 26 that is interlocked and connected to the first intake valve 12a, a second drive rocker arm 28 that is interlocked and connected to the second intake valve 12b, and first and second drive rocker arms. Free rocker arms 27 arranged between 26 and 28 are respectively pivoted adjacent to each other.

Tappet screws 31 are screwed into the first and second drive rocker arms 26, 28 so that they can move forward and backward, and these tappet screws 31 connect the corresponding intake valves 12a, 12b.
touches the top edge of the Therefore, both intake valves 12a, 12b
will operate in response to the rocking movement of the redrive rocker arm 26,28.

The free rocker arm 27 is resiliently biased in the direction of sliding contact with the high-speed cam 23 by resilient biasing means 30 (see FIG. 1) interposed between the free rocker arm 27 and the cylinder head 3.

The hydraulic connection switching means 29 connects the first driving Ronca arm 26
and a first switching pin 32 capable of connecting the free rocker arm 27, a second switching pin 33 capable of connecting the free rocker arm 27 and the second driving rocker arm 28, and movement of the first and second switching pins 32,33. It is provided with a regulation pin 34 for regulation and a return spring 35 for urging each pin 32 to 34 toward the disconnection side.

The first drive rocker arm 26 includes a free rocker arm 27.
A first guide hole 36 with a bottom and open to the side is bored parallel to the rocker shaft 25, and the first guide hole 36 is formed in a cylindrical shape.
The switching pin 32 is slidably fitted into the first guide hole 36, and a hydraulic chamber 37 is defined between one end of the first switching pin 32 and the closed end of the first guide hole 36. Furthermore, the first drive rocker arm 26 is provided with a passage 38 communicating with a hydraulic chamber 37, and the rocker shaft 25 is provided with an oil supply passage 39. The oil supply passage 39 is always in communication with the hydraulic chamber 37 via the passage 38 regardless of the swinging state of the first drive rocker arm 26. Moreover, the oil supply path 39 is connected to a hydraulic pressure supply source 41 via a control valve 40, and the control valve 40 is connected to a hydraulic pressure supply source 41 via a control valve 40.
The oil pressure from 1 can be switched between high and low levels and supplied to the oil supply path 39, that is, the oil pressure chamber 37.

A guide hole 42 corresponding to the first guide hole 36 is bored in the free rocker arm 27 in parallel with the rocker shaft 25 and extends between both sides, and one end is brought into contact with the other end of the first switching pin 32. The second switching pin 33 is connected to the guide hole 42
is slidably fitted to.

A bottomed second guide hole 43 corresponding to the guide hole 42 is provided in the free rocker arm 28 in the second drive rocker arm 28 .
A disc-shaped regulation pin 34, which is opened to the side and is bored parallel to the rocker shaft 25 and comes into contact with the other end of the second switching pin 33, is slidably fitted into the second guide hole 43. A cylindrical guide member 44 is inserted and fixed at the closed end of the second guide hole 43, and a rod 45 that is movably inserted into the guide member 44 is provided coaxially and integrally with the regulating pin 34. . Therefore, the return spring 35 is inserted into the second guide hole 43.
The pins 32, 33, and 34 that are in contact with each other are urged toward the hydraulic chamber 37 by the spring force of the return spring 35.

In such a hydraulic connection switching means 29, the first switching pin 32 moves into the guide hole 4 as the hydraulic pressure in the hydraulic chamber 37 increases.
2, the second switching pin 33 is fitted into the second guide hole 43, and the rocker arms 26, 27, 28 are connected. Further, when the oil pressure in the hydraulic chamber 37 becomes low, the spring force of the return spring 35 causes the first switching pin 32 to move to the second switching pin 3.
3 returns to the position where the abutment surface with the first drive rocker arm 26 and the free rocker arm 27 corresponds, and the second switching pin 33 moves the abutment surface with the regulation pin 34 between the free rocker arm 27 and the second drive rocker arm 28. Since each rocker arm 26, 27, 28 is returned to the corresponding position, the connection state of each rocker arm 26, 27, 28 is released.

Therefore, in the intake side valve operating device 19, when the hydraulic connection switching means 29 is in the disconnected state, the first intake valve 12a
curve L in FIG. 5 in a manner according to the shape of the low-speed cam 22.
The second intake valve 12b is opened and closed as shown by IA, and the second intake valve 12b is configured in a manner corresponding to the shape of the resting cam 24, that is, the resting cam 2
Curve L11 in FIG. 5 at a position corresponding to the high part 24b of No.
As shown in , it operates to the extent that it is essentially in a dormant state.

Further, when the hydraulic connecting means 29 is in the connected state, the first and second intake valves 12a, 12b are aligned with the curve H8 in FIG.
As shown, the opening and closing operations are performed in a manner according to the shape of the high-speed cam 23.

The exhaust side valve train 20 basically has almost the same configuration as the intake side valve train 19, but a low speed cam is used in place of the stop cam 24. Therefore, in the disconnected state, the re-exhaust valve 1
3a and 13b open and close according to the shape of the low-speed cam, and in the connected state, the re-exhaust valves 13a and 13b open and close according to the shape of the high-speed cam, as shown by curve H2 in FIG. do.

Next, the operation of this embodiment will be explained. When the engine is operated at low speed, the hydraulic connection switching means 29 is controlled by the control valve 40.
The oil pressure in the oil pressure chamber 37 is kept at a low pressure. In this state, the intake-side valve operating device 19 brings the second intake valve 12b into a substantially inactive state, and opens and closes the first intake valve 12a in a manner corresponding to the low-speed operation of the engine according to the shape of the low-speed cam 22. .

Therefore, when the first intake valve 12a is opened, the combustion chamber 5
The air-fuel mixture is drawn into the tank at a relatively high speed. Moreover, since the swirl-generating intake port 8 is spirally connected to the first intake valve 6a, the air-fuel mixture is introduced into the combustion chamber 5 at a relatively high speed while swirling. A powerful swirl occurs. Therefore, it is possible to improve combustibility in a fuel lean state at low engine speeds and to reduce fuel consumption.

Moreover, since the second intake valve 12b is almost in a resting state during this low-speed operation, it does not adversely affect the generation of swirl in the combustion chamber 5, and an increase in driving force due to opening/closing operations can be avoided.

However, the second intake valve 12b opens slightly when the first intake valve 12a opens due to the high portion 24b of the stop cam 24. This is to prevent fuel from accumulating in the main intake port 9 when the second intake valve 12b is completely stopped in the closed state. When the valve 12b is opened, it can be prevented from flowing into the combustion chamber 5 all at once and causing smoke generation and abnormal combustion. In addition, if the valve is completely stopped, there is a risk that the second intake valve 12b may stick to the seat portion of the second intake valve 6b, and there is also a risk that operational lubrication may deteriorate, but such concerns are eliminated. .

During high-speed operation of the engine, a high hydraulic pressure is applied to the hydraulic chamber 37 of the hydraulic connection switching means 29 by the control valve 40, thereby integrally connecting the rocker arms 26, 27, 28 of the intake side valve operating device 19. As a result, both intake valves 12a and 12b open and close in a manner that corresponds to the shape of the high-speed cam 23, and by improving the filling efficiency in the combustion chamber 5, high rotation and high output can be achieved.

Moreover, since there is nothing in the swirl-generating intake port 8 and the main intake port 9 that increases intake resistance, it is possible to improve the filling efficiency and increase the output compared to the conventional ones.

In the above embodiment, the second intake valve 12 is
Although b is almost at rest, it may be completely at rest.

Effects of the C0 Invention As described above, according to the present invention, the engine body has a spiral-shaped intake port for generating a swirl that communicates with the first intake valve port, and a main intake port that has a substantially linear shape and communicates with the second intake valve port. An intake port is provided, and the valve operating device operates in a state in which the first intake valve is operated in an operating mode corresponding to low-speed operation while the second intake valve is at rest or almost at rest during low-speed engine operation, and in a state in which the first intake valve is operated in an operating mode corresponding to low-speed operation. The 1st and 2nd 'a & air valves are made in an operating mode that supports high-speed operation! During low-speed operation, the first intake valve opens and closes in response to low-speed operation, causing the swirl-generating intake port to swirl the air-fuel mixture in the combustion chamber. At the same time, the second intake valve is brought into a resting or almost resting state to enhance the swirl effect, thereby reducing fuel consumption and driving force.

Furthermore, when the engine is operating at high speed, both intake valves are opened and closed in a manner compatible with the high speed operation, thereby reducing intake resistance at both intake ports and contributing to high rotation and high output.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a vertical sectional view of the main part of an internal combustion engine, FIG. 2 is a view taken along the line ■-■ in FIG. 1, and FIG.
Figure 3 is a sectional view taken along the ■-■ line in Figure 1, and Figure 4 is the r
FIG. 5, a sectional view taken along the line V-IV, is a diagram showing the opening/closing timing and lift amount of the intake valve and the exhaust valve. 5... Combustion chamber, 6a... First intake valve port, 6b...
Second intake valve port, 8...Intake port for swirl generation, 9
...Main intake port, 12a...First intake valve, 12b
...Second intake valve, 19...Valve train, E...Engine body

Claims (1)

[Claims] First and second intake valves are provided in the engine body facing the combustion chamber, and are capable of opening and closing first and second intake valves. In an intake system for an internal combustion engine connected to a valve train whose operating state can be changed between high-speed operation and high-speed operation, the engine body includes a swirl-generating intake port that is spirally connected to a first intake valve port, and a A main intake port that is straight and communicates with the second intake valve port is provided, and the valve gear is configured to connect the main intake port to the second intake valve port when the engine is running at low speed.
A state in which the first intake valve is operated in an operating mode compatible with low-speed operation while the intake valve is at rest or almost at rest, and a state in which the first and second intake valves are operated in an operating mode compatible with high-speed engine operation when the engine is running at high speed. An intake system for an internal combustion engine, characterized in that it is configured to be able to switch between.