JPH0742408U - Intake device for multi-valve engine - Google Patents

Abstract

(57) [Summary] [Purpose] In a system equipped with an intake port for tumble and an ordinary intake valve, a strong tumble flow is appropriately generated and maintained at a low load. [Configuration] At least normal intake ports 11a and 11b
To form the tumble intake port 13 by branching, and the normal intake valves 14a and 14b and the tumble intake valve 15 are opened and closed by the normal intake ports 11a and 11b and the tumble intake port 13, respectively. To set up. The tumble intake port 13 has a small port diameter and a small inclination. Further, the valve operating mechanism 20 causes the intake cam 37 to rotate so that the normal intake valves 14a, 14b
And the tumble intake valve 15 are respectively lifted, and the normal intake valves 14a, 14b are provided at the time of low load.
The valve stopping device 40 is provided so as to stop only the lift of the valve.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an intake device for a multi-valve engine in which four intake and exhaust ports and one tumble intake port are provided in the combustion chamber of one cylinder, and a valve is provided at each port. The arrangement of the tumble intake port and the valve operating mechanism of these three intake valves are described.

[0002]

[Prior art]

 It is effective to promote combustion in order to improve fuel efficiency and output during engine operation. As a method of promoting this combustion, when various swirling flows are generated in the cylinder during the intake stroke, this swirling flow promotes the mixing of fuel and air, or produces turbulent flow during combustion, which is highly effective. Here, when a transverse swirl flow that swirls in the circumferential direction in the cylinder is generated as the swirling flow, it is effective in homogenizing the air-fuel mixture, but the effect of turbulent flow in the combustion chamber is low. On the other hand, if a tumble flow (vertical swirl) that swirls in the axial direction in the cylinder is generated, it will be greatly disturbed when the tumble collapses in the latter half of the compression stroke, creating a strong turbulent flow in the combustion chamber, which directly contributes to combustion promotion. Expected to do. Therefore, it is desirable to improve the intake system of the engine to generate a tumble flow in the combustion chamber during intake at low speed and low load.

Various methods of generating a tumble flow have been proposed here. One of them is to add a tumble intake port and an intake valve to a 4-valve engine to form a 5-valve multi-valve engine. According to this method, it is necessary to arrange the intake port for tumble, the valve operating mechanism of the intake valve, and the like so that the tumble flow can be optimally generated under the operating condition of low load.

Conventionally, as for the intake device of the multi-valve engine, there is a prior art disclosed in, for example, Japanese Patent Application Laid-Open No. 2-30921. In this prior art, the tumble intake port located at the center of the three intake ports is formed so that the inclination angle with respect to the piston upper surface is closer to the vertical direction than the other intake ports, and the tumble intake port is formed. It has been shown to open the valve earlier than other intake valves.

[0005]

[Problems to be solved by the device]

 By the way, in the above-mentioned prior art, since the tumble intake port is formed close to the vertical direction, the intake flow from that port flows into the cylinder along its approximate axis and immediately after the piston head As it collides with the and decreases the flow velocity and splits into left and right, it is difficult to generate a strong tumble flow that swirls in the cylinder axis direction. Even if a tumble flow is generated at the beginning of the intake stroke because the opening timing of the tumble intake valve is early, a large amount of the intake flow will flow in the latter half of the cycle, and the tumble flow will disappear due to this intake flow. I will end up. Therefore, there is a problem in that the tumble flow cannot be maintained even if the valve opening timing changes.

In view of such a point, the present invention aims to generate and sustain a properly strong tumble flow at a low load by using a tumble intake port and an intake valve.

[0007]

[Means for Solving the Problems]

 In order to achieve this object, the present invention is formed by branching the tumble intake port from at least the normal intake port, and the normal intake valve and the tumble intake valve are provided in the normal intake port and the tumble intake port. In an intake system for a multi-valve engine that is opened and closed by a valve mechanism, the tumble intake port has a small port diameter and is formed with a small inclination, and the valve mechanism is a tumble valve that can be tumbled with a normal intake valve by rotating an intake cam. Each intake valve is designed to be lifted, and a valve stop device is provided to stop only the normal lift of the intake valve when the load is low.

[0008]

[Action]

 According to the present invention having the above-described structure, at a low load during engine operation, the valve intake device of the valve mechanism stops the normal intake valve and only the tumble intake valve opens and closes. Then, when the tumble intake valve opens during the intake stroke, the intake flow enters the radial direction inside the cylinder at a high velocity due to the shape of the tumble intake port, which causes a strong tumble flow that swirls in the cylinder axial direction up to the compression stroke. It occurs continuously and promotes combustion. At medium and high loads, the normal intake valve also opens and closes, and a large amount of air is taken in at once by the normal intake port and the tumble intake port, and the engine output increases due to high filling efficiency.

[0009]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. An outline of a multi-valve engine will be described with reference to FIGS. 1 to 3. Reference numeral 1 denotes an engine body. A piston 4 is reciprocally inserted into a cylinder 3 of a cylinder block 2, and a combustion chamber 6 is provided at the top of the cylinder 3 in a cylinder head 5. The combustion chamber 6 is a roof type, and an ignition plug (not shown) is attached to the center of the top between the pent roof 7 on the intake side and the exhaust side.

In the intake system, two normal intake ports 1 1 a and 11 b are branched from one intake manifold 10 by a branch wall 12 in a bifurcated manner, and these normal intake ports 1 1 a and 11 b are connected to the combustion chamber 6. Connected to one side. Further, as a tumble generating means, one tumble intake port 13 is branched and attached to a lower portion between the two normal intake ports 11a and 11b. The tumble intake port 13 is formed in a state in which the port diameter is small and the inclination is small as shown in FIG. 4, and an intake flow having a high flow velocity can be introduced in the radial direction of the cylinder 3.

These two ordinary intake ports 11a, 11b are respectively provided with ordinary intake valves 14a, 14b which can be opened and closed, and one tumble intake port 13 has a tumble intake valve 15 similarly. It is installed so that it can be opened and closed. Further, two bifurcated exhaust ports 16a, 16b are connected to the other side of the combustion chamber 6, and exhaust valves 17a, 17b are also installed in the exhaust ports 16a, 16b so as to be openable and closable, and a multi-valve of 5 valves is provided. Composed into an engine. Further, an injector 18 is arranged in the intake manifold 10 so as to direct fuel to the tumble intake port 13 which is always open at least.

A valve operating mechanism of five valves will be described with reference to FIGS. 1, 2, and 5. On the exhaust valve side of the valve mechanism 20, the retainer 21 of the exhaust valves 17a and 17b is urged in the direction in which the valve spring 22 is closed, and the rocker arm that is cantilevered by the rocker shaft 23 at the stem end of the exhaust valves 17a and 17b. 24 is abutted via the adjusting screw 28. An exhaust cam 27 of a cam shaft 26 is arranged on a roller 25 in the middle of the rocker arm 24 so as to lift the valve by its rotation.

On the intake valve side, the valve spring 31 is similarly biased to the retainer 30 of the normal intake valves 14a and 14b. It also has a rotatable rocker shaft 32, and two levers 33a, 33b integral with the rocker shaft 32 are attached to the stem ends of two ordinary intake valves 14a, 14b via adjusting screws 38, respectively. Contacted. A rocker arm 35 including a roller 34 and a valve stopping device 40 is rotatably provided on the rocker shaft 32, and an intake cam 37 of a cam shaft 36 is arranged immediately above the roller 34.

As shown in FIG. 6, the valve stopping device 40 has a piston 41 movably inserted in a radial direction inside the rocker shaft 32 and the rocker arm 35, with a return spring 42, so that An oil hole 43 is formed inside the piston 41. The oil passage 44 on the oil pump side communicates with the oil hole 43 via the switching valve 45. Further, it has a control unit 46 for judging the engine operating state by various sensor signals, and the signal of this control unit 46 causes the switching valve 45 to operate on the drain side at a low load to stop the valve, and for a medium or high load. It is configured to operate on the refueling side and lift the valve.

A valve spring 51 is also urged to the tumble intake valve 15 via a retainer 50. A rocker arm 53 having a roller 52 between the two levers 33a and 33b has one end supported by a holder 54 on the cylinder head side by a pivot 54, and the other end abutting on the stem end of the tumble intake valve 15. It is mounted in close contact. An intake cam 37 of the cam shaft 36 is arranged immediately above the roller 52 so that the intake cam 37 always lifts the valve due to its rotation. Here, the two rollers 34 and 52 are arranged with a predetermined phase difference in the rotational direction of the intake cam 37 so that the opening angle becomes relatively wide when the valve is opened by the two rollers 34 and 52. Composed.

Next, the operation of this embodiment will be described. First, when the engine is operating and the load is low including idling, the control unit 46 causes the switching valve 45 to move to the drain side to drain the oil hole 43 of the valve pausing device 40. Then, the piston 41 is retracted by the return spring 42 so that the rocker shaft 32 and the rocker arm 35 are separated, so that the rocker arm 35 simply idles despite the rotation of the intake cam 37. For this reason, the two ordinary intake valves 14a and 14b are closed and held by the valve spring 31 to be stopped. On the other hand, in the tumble intake valve 15, the rocker arm 53 swings via the roller 52 by the rotation of the intake cam 37, so that only the tumble intake valve 15 has a narrow opening angle as shown in FIG. 7A during the intake stroke. Lift to open.

Then, when the tumble intake valve 15 is opened, the intake negative pressure generated by the downward movement of the piston 4 is sucked by the intake port 13. Further, when the fuel is injected by the injector 18 during the intake stroke when the load is low, the fuel is mixed with the air and sucked together, so that the air-fuel mixture flows into the cylinder 3.

Here, since the tumble intake port 13 has a small port diameter and a small inclination, the intake flow A of the air-fuel mixture flows in the inside of the cylinder 3 at a high flow velocity as shown in FIG. Therefore, the high-speed intake air flow A is directed downwardly along the wall surface of the cylinder 3 opposite to the normal intake ports 11a and 11b, and then is turned to the intake port side via the head of the piston 4 to reach the wall surface. A strong tumble flow C that flows upwards along the cylinder axis and that swirls in the cylinder axis direction is effectively generated and continues.

In addition, in the compression stroke, the intake flow A in the cylinder 3 is compressed by the movement of the piston 4, so that the tumble flow C also collapses, but when the tumble flow collapses in the latter half of the compression stroke, the flow of the intake flow A changes. The turbulence causes turbulence in the combustion chamber 6. When ignited by an ignition plug (not shown) in the combustion chamber 6, the air-fuel mixture burns at a high combustion speed due to turbulent flow, thus substantially promoting combustion under low load.

At medium and high loads, the control unit 46 causes the switching valve 45 to operate on the oil supply side so that the oil pressure in the oil passage 44 is introduced into the oil hole 43. Then, the piston 41 moves forward by hydraulic pressure, and the rocker shaft 32 and the rocker arm 35 are integrally connected. Therefore, this time, the rotation of the intake cam 37 causes the rocker arm 35, the rocker shaft 32, and the two levers 33a and 33b to swing together via the roller 34, thereby opening and closing the two normal intake valves 14a and 14b. Come to do. Therefore, in this operating region, the three intake valves 14a, 14b, 15 are opened in the intake stroke, and in this case, the two ordinary intake valves 14a, 14b and the one tumble intake valve 15 are used to open the entire valve. The corner lifts and opens with a wide opening angle as shown in Fig. 7 (b). Therefore, a large amount of air flows into the cylinder 3 at a time, and the filling rate increases, which improves the engine output characteristics.

Although the embodiment of the present invention has been described above, the present invention can be applied to a valve operating mechanism other than the rocker arm type.

[0022]

[Effect of device]

 As described above, according to the present invention, in the intake system for a multi-valve engine that includes an intake port for tumble and an intake valve, the intake port for tumble has a small port diameter and a small inclination to form a valve operating valve. The mechanism is configured to lift each of the normal intake valve and the tumble intake valve by the rotation of the intake cam, and is also provided with a valve pausing device so that only the normal intake valve lift is stopped when the load is low. Therefore, when the load is low, the intake flow can flow in the cylinder radial direction at a high flow rate only by the tumble intake port, and a strong tumble flow can be appropriately generated. At medium and high loads, the normal intake valve opens at a wide opening angle and is taken in by the normal intake port and the tumble intake port, increasing the engine output.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of an intake system for a multi-valve engine according to the present invention.

FIG. 2 is a development view of the main part.

FIG. 3 is a horizontal sectional view of the same.

FIG. 4 is a sectional view of an intake port.

FIG. 5 is a perspective view of a valve mechanism on the intake valve side.

FIG. 6 is a configuration diagram showing a partial cross section of a valve pausing device.

FIG. 7 is a characteristic diagram of a valve lift.

[Explanation of symbols]

 11a, 11b Normal intake port 13 Tumble intake port 14a, 14b Normal intake valve 15 Tumble intake valve 20 Valve mechanism 37 Intake cam 40 Valve rest device

Claims (2)

[Scope of utility model registration request] 1. A tumble intake port is formed by branching from at least a normal intake port, and a normal intake valve and a tumble intake valve are opened and closed by the normal intake port and the tumble intake port, respectively. In a multi-valve engine intake device installed like this, the tumble intake port has a small port diameter and a small inclination, and the valve mechanism lifts the normal intake valve and the tumble intake valve by the rotation of the intake cam. An intake device for a multi-valve engine, which is configured as described above, and is provided with a valve pausing device for pausing only the lift of a normal intake valve when the load is low. 2. A normal intake port is two intake ports formed in a bifurcated shape, and one tumble intake port is branched and formed at a lower part between the two intake ports, 2. The intake device for a multi-valve engine according to claim 1, wherein the valve mechanism is arranged such that two sliding contact portions of the intake cam, the normal intake valve, and the tumble intake valve are out of phase with each other.