JPH086570B2 - Internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Objects of the Invention (1) Field of Industrial Application The present invention is mainly for opening and closing one of a pair of intake valves in an intake stroke in a low speed operation range of an engine. The valve operating device having a cam shaft provided with a plurality of cams including the opening / closing operation cam, and the minute operation cam for opening the other intake valve by a minute amount to a substantially rest state, A valve operating characteristic switching means that can switch the operating characteristics of both intake valves according to the operating state of the engine is provided, and a fuel injection valve that injects fuel in an intake stroke to an intake system connected to the pair of intake valves is provided. It relates to an internal combustion engine.

(2) Conventional Technology In the related art, one of a pair of intake valves is lifted by a small amount in the engine low speed operation range to prevent an increase in fuel consumption in the engine low speed operation range and to substantially prevent intake air from being closed. An internal combustion engine which avoids fuel retention in a port and stabilizes fuel is disclosed in, for example, Japanese Utility Model Laid-Open No. 60-195913.

(3) Problems to be Solved by the Invention Like the above-mentioned conventional one, the intake valve is slightly opened and closed so that one intake valve is opened and closed mainly in the low speed operation range of the engine, and the other intake valve is substantially closed. When opened, the air-fuel mixture practically flows from only one intake valve side into the combustion chamber to form a swirl in the combustion chamber to improve combustibility and to the intake port on the other intake valve side. It is possible to avoid the fuel accumulation and the sticking of the other intake valve to the valve seat.

However, depending on the timing of opening the other intake valve slightly, there is a risk that swirl generation due to air-fuel mixture inflow from one intake valve side may be hindered, and depending on the opening timing of the fuel injection valve, the other intake valve It may not be possible to achieve a good stratified charge due to the slight opening of the intake valve, so that it is necessary to appropriately select the timing of slightly opening the other intake valve and the timing of opening the fuel injection valve.

Further, when switching the valve operating characteristics by the valve operating characteristic switching means, the switching may fail, and when switching from the state in which the other intake valve is substantially inactive to the opening / closing driving by the opening / closing operation cam. When switching fails in
It is possible to prevent the intake valve from colliding with the valve seat by impact by restricting the operation of the intake valve in the valve closing direction by the minute operation cam, but depending on the opening angle of the minute operation cam,
When the switching fails, the magnetic valve may reverse from the middle of operating in the valve opening direction up to a comparatively high lift and may operate in the valve closing direction to collide with the valve seat.

The present invention has been made in view of such circumstances,
The timing of opening the intake valve by the minute actuation cam so that the swirl generation from one intake valve is not hindered as much as possible and the impact of the intake valve can be mitigated when the valve operation characteristic switching means fails to switch. And to provide an internal combustion engine in which the fuel injection end timing of the fuel injection valve is determined such that good stratified charge can be achieved and the torque fluctuation can be effectively suppressed even by a slight opening operation of the intake valve. With the goal.

B. Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, according to the invention described in claim 1, the minute actuation cam mainly opens and closes in a low speed operation range of the engine. The intake cam has an opening center time on the side of the opening angle of the opening lift curve of one intake valve, and an ending time near the end of the buffer curve portion along the crank angle of the opening lift curve. The intake valve is formed to open the other intake valve with a small lift curve, and the fuel injection end timing of the fuel injection valve is set in the first half of the intake stroke in the operating state in which only the one intake valve is substantially opened and closed. .

According to the invention of claim 2, in addition to the configuration of the invention of claim 1, the maximum lift portion of the minute lift curve by the minute operation cam is the maximum lift of the valve opening lift curve by the opening / closing operation cam. According to the invention of claim 1, further to the configuration of the invention of claim 1 or 2, in addition to the configuration of the invention of claim 1 or 2, A plurality of valve drive members provided adjacent to each other between the pair of intake valves are provided, and the valve operating characteristic switching means is configured to be able to switch connection and disconnection between the adjacent valve drive members.

(2) Operation According to the configuration of the invention of the above-mentioned claim 1, the other intake valve is driven by the minute cam later than the one intake valve which is driven to be opened / closed by the opening / closing cam mainly in the intake stroke in the low speed operation range of the engine. Can be opened slightly, and the adverse effect on swirl generation due to the slight opening of the other intake valve can be avoided as much as possible, and when the valve operation characteristic switching by the valve operation characteristic switching means fails, the other After the intake valve is opened to a relatively high lift, direct collision with the valve seat is avoided by regulating the minute actuation cam.

Moreover, by setting the fuel injection end timing in the first half of the intake stroke in which the other intake valve is almost not opened,
Good stratified air supply is achieved, and torque fluctuations can be suppressed as much as possible.

Further, in particular, according to the configuration of the invention of claim 2, the maximum lift portion of the minute lift curve by the minute operation cam is set to the rear side along the crank angle with respect to the maximum lift portion of the valve opening lift curve by the opening / closing operation cam. By doing so, the action of the invention of claim 1 is further promoted.

(3) Examples Hereinafter, examples of the present invention will be described with reference to the drawings.

1 to 7 show an embodiment of the present invention. FIG. 1 is an overall configuration diagram, FIG. 2 is an enlarged plan view of a partial notch along line II-II of FIG. FIG. 3 is a diagram showing the relationship between the intake valve operating state and fuel injection timing, and FIG. 4 is a graph showing experimental results of the effect of fuel injection timing on fuel stability.
FIG. 5 is a graph showing the experimental result of the influence of the fuel injection end timing on the torque fluctuation rate, and FIG. 6 is the experimental result of the influence on the combustion limit due to the difference in the opening angle center timing of the intake valve in the substantially idle state. The graph shown in FIG. 7 is a graph showing the experimental results of the influence on the torque fluctuation rate, the fuel consumption, and the exhaust gas property due to the difference in the center timing of the opening angle of the intake valve in the substantially resting state.

First, in FIG. 1, a cylinder head 2 is coupled to an upper surface of a cylinder block 1 and upper surfaces of a plurality of cylinders 3 provided in the cylinder block 1 so as to constitute a main part of an engine body in an SOHC type multi-cylinder internal combustion engine. Pistons 4 each having a recess 4a are slidably fitted therein, and combustion chambers 5 are formed between the upper surfaces of the pistons 4 and the cylinder head 2.

A pair of intake valve openings 6 and a pair of exhaust valve openings 7 are provided in the cylinder head 2 so as to open to the ceiling surface of the combustion chamber 5. Further, the cylinder head 2 has a pair of intake ports 8 branching from a single intake opening end 9 opening on one side surface thereof and continuously connected to the pair of intake valve openings 6, and a pair of exhaust valve openings 7. A pair of exhaust ports 10 that are individually connected and that are commonly connected to a single exhaust opening end 11 that is opened on the other side surface of the cylinder head 2 are provided. A pair of intake valves V _I1 and V _I2 that can open and close both intake valve openings 6 individually are slidably fitted to a pair of guide cylinders 12 arranged on the cylinder head 2, respectively. From each intake valve V _I1 ,
Between the retainer 13 fixed to the upper end of V _I2 and the cylinder head 2, coiled valve springs 14 surrounding the intake valves V _I1 and V _I2 are provided, respectively.
As a result, the intake valves V _I1 and V _I2 are urged upward, that is, in the valve closing direction. Further, a pair of exhaust valves V _E1 and V _E2 capable of individually opening and closing both exhaust valve openings 7 are slidably fitted to a pair of guide cylinders 15 arranged on the cylinder head 2, respectively. Between the retainer 16 fixed to the upper ends of the exhaust valves V _E1 and V _E2 protruding from the cylinder 15 and the cylinder head 2, there are coiled valve springs 17 surrounding the exhaust valves V _E1 and V _E2. Each exhaust valve V is installed by its respective valve spring 17.
_E1 and V _E2 are urged upward, that is, in the valve closing direction.

Referring also to FIG. ₂ , a valve train 18 is connected to both intake valves V _I1 and V _I2 and both exhaust valves V _E1 and V _E2 . The valve operating device 18 rotates a single camshaft 19 linked to a crankshaft (not shown) at a speed reduction ratio of 1/2 and rotational movement of the camshaft 19 to open and close both intake valves V _I1 and V _I2 . The first and second intake-side rocker arms 20 and 21 as valve drive members for converting to and the first and second rotational motions of the camshaft 19 to the opening and closing motions of both exhaust valves V _E1 and V _E2. The second exhaust-side rocker arms 22 and 23 are provided.

The camshaft 19 includes a cylinder head 2 and holders 24 that are respectively coupled to the cylinder head 2 on both sides of the cylinder 3 along the axis of the crankshaft 19 and have a horizontal axis perpendicular to the axis of the cylinder 3. While being rotatably supported.

The cam shaft 19 is integrally provided with an intake side opening / closing operation cam 25 and a minute operation cam 26 adjacent to one side of the cam 25. The intake side opening / closing operation cam 25 and the minute operation cam are also provided. Exhaust side opening / closing operation cams 27,2 on both sides of cam 26
7 are provided integrally. The micro-actuating cam 26 is basically a circle centered on the axis of the camshaft 19 so that one of the intake valves V _I1 and V _I2 , V _I2, is substantially in a resting state mainly in the low speed operation region of the engine. Although it is formed so as to have an outer surface, a slightly protruding projection is provided at a position corresponding to the high position of the intake side opening / closing operation cam 25. Moreover, the width of the micro-actuation cam 26 in the direction along the axis of the cam shaft 19 is set to be relatively narrow.

The one of the intake valves V _I1 is the first intake-side rocker arm 20 interlocking is connected, the other intake valve V _I2 second intake-side rocker arm 21 is linked, coupled, the intake-side rocker arm 20, 2
1 is a position diagonally above the camshaft 19
An intake side rocker shaft 28 fixedly supported by a holder 24 while having an axis parallel to 9 is swingably supported.
Both exhaust side rocker arms 22 and 23 are individually interlocked and connected to both exhaust valves V _E1 and V _E2 , and are arranged in a holder 24 in a position diagonally above the cam shaft 19 in parallel with the intake side rocker shaft 28. Exhaust rocker shaft 29 fixedly supported
It is rockably supported by.

A roller 30 adjacent to the intake side opening / closing operation cam 25 is pivotally supported at one end of the first intake side rocker arm 20, and a sliding contact portion 31 slidingly contacting the minute operation cam 26 is provided at one end of the second intake side rocker arm 21. It is provided with a narrow width corresponding to the minute actuation cam 26. Further, rollers 32, which are in sliding contact with the exhaust side opening / closing operation cams 27, 27, are axially supported at one ends of both the exhaust side rocker arms 22, 23, respectively.

The other end of each of the first and second intake-side rocker arms 20 and 21 has a tappet screw 33 that abuts the upper ends of the intake valves V _I1 and V _I2.
Are respectively screwed so that they can move back and forth, and the intake valves V _I1 and V _I2 are opened and closed according to the swinging operation of both intake side rocker arms 20 and 21. Also, both exhaust side rocker arms 22, 23
A tappet screw 34, which abuts on the upper ends of the exhaust valves V _E1 and V _E2 , is screwed into the other end of the exhaust valve V _E1 and V _{E2 so} as to move back and forth. V _E1,, V
_E2 will open and close.

The intake-side rocker arms 20 and 21 have two intake-side rocker arms 20 and 21 in order to switch the operating characteristics of the intake valves V _I1 and V _I2 mainly between the low-speed rotation range of the engine and the high-speed rotation range of the engine. Connected state, both intake side rocker arm 20,
A valve operating characteristic switching means 35 capable of switching the connection release state of 21 is provided.

This valve operating characteristic switching means 35 is provided on both intake side rocker arms.
Connection piston 36 that can connect 20, 21 and connection piston 36
And a return spring 38 that urges the connecting piston 36 and the restricting member 37 toward the disconnection side.

The connecting piston 36 is slidable on the first intake-side rocker arm 20 while defining a hydraulic chamber 39 between one end thereof and the first intake-side rocker arm 20 so as to be movable in the axial direction parallel to the intake-side rocker shaft 28. It is possible to be fitted. A communication passage 40 communicating with the hydraulic chamber 39 is formed in the first intake-side rocker arm 20, and the communication passage 40, that is, the communication passage 40, is formed in the intake-side rocker shaft 28 regardless of the swinging state of the first intake-side rocker arm 20. An oil passage 41 (see FIG. 1) that is in constant communication with the hydraulic chamber 39 is provided. As shown in FIG. 1, the oil passage 41 is connected to a hydraulic pressure source 43 via a connection switching electromagnetic control valve 42.

The connecting piston 36 is attached to the second intake-side rocker arm 21.
A closed-end cylindrical regulation member 37 whose closed end is in contact with the other end of the is fitted slidably. Further, the return spring 38 is contracted between the second intake side rocker arm 21 and the regulating member 37, and the connecting piston 36 and the regulating member 37, which are brought into contact with each other by the spring force of the return spring 38, move toward the hydraulic chamber 39 side. Be energized.

In the valve operating characteristic switching means 35, the hydraulic chamber is controlled by the connection switching electromagnetic control valve 42 mainly in the low speed operation range of the engine.
The hydraulic pressure of 39 is released, and the contact surface of the connecting piston 36 and the regulating member 37 is located at a position corresponding to between the first and second intake-side rocker arms 20 and 21 due to the spring force of the return spring 38. Therefore, both intake side rocker arms 20 and 21 are in a state where they can be displaced relative to each other, and the rotation of the cam shaft 19 causes the first intake side rocker arm 20 to swing in accordance with the sliding contact with the intake side opening / closing operation cam 25. Then, one intake valve V _I1 opens and closes at the timing and lift amount according to the shape of the intake cam 25. Further, the second intake-side rocker arm 21 that is in sliding contact with the minute actuation cam 26 is substantially in a resting state, and the other intake valve V _I2 can be substantially resting. Moreover, the intake valve V _I2 does not completely rest, but one intake valve V _{I2
When I1} opens, the valve slightly operates in the opening direction, so that it is possible to prevent the intake valve V _{I2 from} sticking to the valve seat and accumulating fuel, which occurs when the valve is completely closed. Further, the exhaust valves V _E1 and V _E2 are connected to the exhaust side opening / closing operation cams 27 and 27.
It opens and closes at the timing and lift according to the shape of.

By the way, the intake valve V _I1
In contrast to the valve opening lift curve C ₁ of Fig. 3, the minute lift curve C ₂ of the intake valve V _I2 by the cam for minute operation 26 is set as shown in Fig. 3 (a). That is, the opening angle center timing θ _C2 of the minute lift curve C ₂ is set on the retard side along the crank angle with respect to the opening angle center timing θ _C1 of the valve opening lift curve C ₁ , and desirably,
The maximum lift portion C _2M of the small lift curve C ₂ is the valve opening lift curve C
It is set to the retard side along the crank angle than the _first maximum lift portion C _1M. Moreover, the terminal timing θ _VC of the minute lift curve C ₂ is
Buffer curve section at the end along the crank angle of the valve opening lift curve C ₁
It is set near C _1S .

Further, mainly during high-speed operation of the engine, the connection switching electromagnetic control valve 42 is opened, and the high hydraulic pressure in the hydraulic chamber 39 is applied. As a result, the connecting piston 36 tries to move in the direction of increasing the volume of the hydraulic chamber 39 against the spring force of the return spring 38, and when the axes of the connecting piston 36 and the regulating member 37 coincide, that is, both intake side rocker arms 20. , 21 enters the stationary state, the connecting piston 36 fits into the second intake-side rocker arm 21, both intake-side rocker arms 20, 21 are in a connected state, and are in sliding contact with the intake-side opening / closing operation cam 25. The first intake-side rocker arm 20 swings together with the first intake-side rocker arm 20,
Both intake valves V _I1 and V _I2 are opened / closed at a timing and a lift amount (a profile shown by a valve opening lift curve C ₁ in FIG. 3A) according to the shape of the intake side opening / closing operation cam 25. Further, both exhaust side rocker arms 22 and 23 open and close both exhaust valves V _E1 and V _E2 at the timing and lift amount according to the shape of the exhaust side opening / closing operation cams 27 and 27 as in the low speed operation range.

The cylinder head 2 has rocker arms 22 and 23 on both exhaust sides.
A plug tube portion 44 is provided so as to incline sideways as it goes upward between them, and an ignition plug 45 inserted from this plug tube portion 44 has a cylinder head 2 at a substantially central portion of the ceiling surface of the combustion chamber 5. Mounted on.

Referring again to FIG. 1, an air cleaner 49 is connected to the intake opening end 9 of the cylinder head 2 via an intake manifold 46 and a throttle body 48 having a throttle valve 47. An intake passage 50 is formed in the throttle body 48 and the intake manifold 46 between the air cleaner 49 and the intake opening end 9, and the intake passage 50 has a bypass passage 51 and a first idle passage 52. Throttle valve 47
A bypass electromagnetic control valve 53 is provided in the bypass passage 51, and a wax valve 54 that operates according to the cooling water temperature of the engine body is provided in the first idle passage 52. It

At the end of the intake manifold 46 on the cylinder head 2 side, an intake system connected to the intake valves V _I1 and V _I2 , specifically, from the intake opening end 9 toward both intake ports 8 is evenly provided in the intake stroke. A fuel injection valve 55 is attached to inject fuel, and a fuel supply source 56 is connected to the fuel injection valve 55.

The fuel injection valve 55 is configured to be able to controllably inject the fuel supplied from the fuel supply source 56 and to inject assist air for atomizing the injected fuel. A passage 57 for supplying the assist air is connected to the fuel injection valve 55. Thus the passage
57 is connected to the air header 58 common to each cylinder,
The air header 58 is connected to the intake passage 50 on the upstream side of the throttle valve 47 via the electromagnetic air amount control valve 59 and the idle adjusting screw 60.

A catalytic converter 62 is connected to the intake opening end 11 of the cylinder head 2 via an exhaust manifold 61.

Electromagnetic control valve 42 for switching the connection, electromagnetic control valve for bypass
The operations of the fuel injection valve 53, the fuel injection valve 55, and the electromagnetic air amount control valve 59 are controlled by a control means 67 composed of a computer, and the control means 67 includes an intake pressure P detected by an intake pressure sensor 64. _B , the cooling water temperature T _W detected by the engine cooling water temperature sensor 65, and the engine speed N _E detected by the rotation speed sensor 66 are input.

And Thus, the control unit 67, a decoupling state the intake side rocker arm 20, 21 so as to substantially pause one V _I2 of the intake valves V _I1, V _I2 when the engine is in the low rotational speed range mainly In addition, when the engine is mainly in the high speed rotation range, the valve operating characteristic switching means is set so that both intake side rocker arms 20 and 21 are connected so that both intake valves V _I1 and V _I2 are opened and closed by the intake side opening and closing operation cam 25. While controlling the operation of 35, when the engine is mainly in the low speed rotation range, that is, when one of the intake valves V _I1 and V _I2 , V _I2, is substantially in the idle state, the fuel injection timing of the fuel injection valve 55 is set to As shown in FIG. 3B, the fuel injection end timing θ _FE is controlled so as to fall within the range of 50 to 90 degrees from the first half of the intake stroke, for example, the intake stroke start TDC.

Next, the operation of this embodiment will be described. When the engine is mainly in the high speed rotation range, the control means 67 connects both intake side rocker arms 20, 21 by the valve operating characteristic switching means 35, and the valve operating device 18 operates both The intake valves V _I1 and V _I2 are opened / closed at the timing and lift determined by the intake side opening / closing cam 25.

Further, when the engine is mainly in the low speed rotation range, the valve operating characteristic switching means 35 is switched by the control means 67 to a state where the connection between the intake side rocker arms 20 and 21 is released. Thus, one VV _I2 of the intake valves V _I1, V _I2 is substantially become dormant, only the other intake valve V _I1 is made to opened and closed with a timing and a lift amount determined by the intake-side opening and closing cam 25 To be

As a result, in the combustion chamber 5, substantially both intake valve ports 6
The air-fuel mixture will flow in from only one side of the combustion chamber 5
A swirl will be formed inside. Moreover, as shown in FIG. 3B, the fuel injection end timing θ _FE by the fuel injection valve 55 at the time of the swirl generation is set in the first half of the intake stroke, preferably in the range of 50 to 90 degrees from the intake stroke start TDC. Therefore, it becomes possible to introduce the injected fuel into the fuel chamber 5 sequentially from the intake valve port 6 corresponding to the intake valve V _I1 which is opening and closing, and achieve the axial stratified charge. Combustibility can be improved as shown in FIG. 4 showing the experimental result, and the torque fluctuation rate can be suppressed to be small as shown in FIG. 5 showing the experimental result of the present inventor.

Further, as shown in FIG. 3 (a), the opening angle center timing θ _C2 of the intake valve V _I2 which is slightly opened by the minute actuation cam 26 is in the intake stroke and is preferably in the latter half of the intake stroke.
It is set in the range of 130 to 180 degrees from TDC, and the maximum lift portion C _2M of the minute lift curve C ₂ is the valve opening lift curve C ₁
It is set on the retard side along the crank angle with respect to the maximum lift section C _1M . With such a setting, it becomes possible to suppress the occurrence of swirl turbulence due to the slight opening of the intake valve V _I2 . Fig. 6 shows the combustion limit for the open angle center timing θ _{C2 as} an experimental result. The open angle center timing θ _C2 is in the intake stroke, and the latter half of the intake stroke is desirable.
It is clear that the lean burn limit is improved by setting the range from 130 to 180 degrees from TDC. Also, the center angle of opening angle θ _C2
Fig. 7 shows the results of experiments conducted by the present inventor regarding the influence of the difference on the torque fluctuation, fuel consumption and exhaust gas properties. The results obtained when the opening angle central timing θ _C2 is set at the center of the intake stroke are shown in Fig. 7. When the open-angle center timing θ _C2 is set to the latter half of the intake stroke when the curve is shown by the broken line, it becomes the curve shown by the solid line, which makes it possible to suppress the torque fluctuation rate and fuel consumption to a low level and to improve the exhaust gas properties. can do.

In such an internal heat engine, a recess 4a is provided on the upper surface of the piston 4 facing the combustion chamber 5, and the recess 4a enables the combustion chamber 5 to be made compact. Further, the valve gear 18 is provided with a single camshaft 19 which is common to both the intake valves V _I1 , V _I2 and the surface exhaust valves V _E1 , V _E2 , and is provided at a substantially central portion of the ceiling surface of the combustion chamber 5. Is provided with a spark plug 45, so that both intake valves V _I1 ,
It is possible to narrow the angle formed by the axes of the two exhaust valves V _E1 and V _{E2 by} V _I2 , which also allows the combustion chamber 5 to be made compact. By making the combustion chamber 5 compact in this way, the swirl speed generated in the combustion chamber 5 can be increased and the combustibility can be further improved.

Further, when the injected fuel is atomized by the assist air in the combustion injection valve 55, the lean burnability is further improved.

Further, by slightly opening the intake valve V _I2 to bring it into a substantially resting state, the fuel injected from the fuel injection valve 55 is prevented from staying in the intake port 8 corresponding to the intake valve V _I2 , and the air-fuel ratio It is possible to avoid fluctuations.

By the way, when the operating region of the engine changes from a state mainly in the low speed rotation range to a state mainly in the high speed rotation range, the valve actuation characteristic switching means 35 causes both intake side rocker arms 20, 21 to be in the connection state from the connection release state to the connection state. At the time of switching to, the connection piston 36 of the valve operating characteristic switching means 35 is slightly fitted into the second intake side rocker arm 21, and the first intake side rocker arm 20 is hit by the intake side cam 25, so that The mated state may be lost and the switching may fail.
Thus, when the switching failure occurs during the operation of the intake valve V _{I1 in} the valve opening direction, the second intake side rocker arm 21 moves together with the first intake side rocker arm 20 while swinging in the valve opening direction. 1 The connection with the rocker arm 20 on the intake side is released, and the intake valve V _I2 opens the valve spring 14 during the opening operation.
This causes reversal operation in the valve closing direction, and when the reversal operation in the valve closing direction occurs at a relatively high lift position, the intake valve V _I2 may be impacted and seated on the valve seat.
However, the camshaft 19 is provided with a minute actuation cam 26 corresponding to the second intake-side rocker arm 21, and the intake valve V _I2 is slightly opened by the minute actuation cam 26.
The opening angle center timing θ _C2 is in the latter half of the intake stroke and the valve closing timing θ _VC is the intake valve opening / closing operation cam 25 intake valve V
It is set at a time corresponding to the vicinity of the buffer curve portion C _1S of the valve opening lift curve C ₁ of _I1 . That is, in the intake stroke after the intake valve V _I1 has been lifted to a relatively high position, when the first and second intake side rocker arms 20, 21 are disconnected, the second intake side rocker arm 21 and the intake valve V _I2 The operation is regulated by the minute operation cam 26. Therefore, even if the intake valve V _I2 reverses from the relatively high lift position to the valve closing direction due to the failure of the valve operation characteristic switching means 35 to switch from the low speed rotation range to the high speed rotation range, the second intake side rocker arm 21
By restricting the valve closing direction operation of the intake valve by the minute operation cam 26, it is possible to prevent the intake valve V _I2 from being seated by shock,
It is possible to prevent the generation of impact noise.

Further, when the engine is mainly in the low speed rotation range, the valve operating characteristic switching means 35 is switched by the control means 67 to a state where the connection between the intake side rocker arms 20 and 21 is released. Thus, one V _I2 of the intake valves V _I1, V _I2 is substantially become dormant, only the other intake valve V _I1 is made to opened and closed with a timing and a lift amount determined by the intake cam 25.

FIG. 8, FIG. 9 and FIG. 10 show another embodiment of the present invention, and the portions corresponding to the above-mentioned embodiment are designated by the same reference numerals.

This valve operating device 18 'includes a cam shaft 19', and first, second, and first valve drive members for converting rotational movements of the cam shaft 19 'into opening / closing movements of both intake valves V _I1 , V _I2 . Three
The intake side rocker arms 71, 72, 73 and the camshaft 19 '
And the first and second exhaust side rocker arms 22 and 23 for converting the rotational movement of the above into the opening and closing movements of both exhaust valves V _E1 and V _E2 .

The camshaft 19 'includes a first intake side opening / closing operation cam 74 having a shape corresponding to the low speed operation of the engine and a first intake side opening / closing operation cam 74 having a shape corresponding to the high speed operation of the engine. Second intake side opening / closing operation cam adjacent to the side
75 and a minute operation cam 76 adjacent to one side of the second intake side opening / closing operation cam 75 are integrally provided, and exhaust is provided on both sides of the first intake side opening / closing operation cam 74 and the minute operation cam 76. Side opening / closing operation cams 27, 27 are integrally provided.

The one of the intake valves V _I1 interlocked first intake-side rocker arm 71, is connected, the third intake-side rocker arm 73 is linked, is coupled to the other intake valve V _I2, with respect to the intake valves V _I1, V _I2 A second intake-side rocker arm 72, which can be free, is arranged between the first and third intake-side rocker arms 71, 73. Thus, the intake-side rocker arms 71 to 73 are the intake-side rocker shafts 28.
It is rockably supported by. In addition, the first and second exhaust side rocker arms that are individually interlocked and connected to both exhaust valves V _E1 and V _E2
22 and 23 are swingably supported on the exhaust side rocker shaft 29.

One end of the first intake side rocker arm 71 is in sliding contact with the first intake side opening / closing operation cam 74, one end of the third intake side rocker arm 73 is in sliding contact with the minute operation cam 76, and the second intake side rocker arm 72 is 2 Sliding contact with the intake side opening / closing operation cam 75. Further, one ends of both the exhaust side rocker arms 22 and 23 are in sliding contact with the exhaust side opening / closing operation cams 27 and 27, respectively.

By the way, a support plate 78 is fixedly provided on the upper end of the holder 24, and the second intake side rocker arm 72 is slidably brought into contact with the second intake side opening / closing operation cam 75 of the cam shaft 19 '. A lost motion mechanism 79 that elastically urges in the direction is provided.

Each intake side rocker arm 71-73 has a valve operating characteristic switching means.
35 'is provided, and this valve operating characteristic switching means 35' is provided.
Is a connecting piston 82 capable of connecting the first intake-side rocker arm 71 and the second intake-side rocker arm 72, a connecting pin 83 capable of connecting the second intake-side rocker arm 72 and the third intake-side rocker arm 73, a connecting piston 82, The regulating member 84 for regulating the movement of the connecting pin 83 and the connecting piston 8
2. A return spring 85 for urging the connecting pin 83 and the regulating member 84 toward the connection release side.

The connecting piston 82 is slidably fitted to the first intake-side rocker arm 71 so as to be movable in the axial direction parallel to the intake-side rocker shaft 28, and is disposed between one end of the connecting piston 82 and the first intake-side rocker arm 71. On the intake side rocker shaft
A hydraulic chamber 86 communicating with the oil passage 41 in 28 is defined. A connecting pin 83, one end of which abuts against the other end of the connecting piston 82, is fitted to the second intake-side rocker arm 72 so as to be slidable in the axial direction parallel to the intake-side rocker shaft 28. Further, a cylindrical bottomed cylindrical regulating member 84 that abuts the other end of the connecting pin 83 is fitted to the third intake side rocker arm 73 so as to be slidable in the axial direction parallel to the intake side rocker shaft 28, and then returned. Spring 85
Is contracted between the restricting member 84 and the third intake-side rocker arm 73.

In the valve operating characteristic switching means 35 ', when the hydraulic pressure in the hydraulic chamber 86 is released mainly in the low speed rotation range of the engine, the return spring 85
Due to the spring force of the connecting piston 82 and the connecting pin 83, the contact surfaces of the connecting pin 82 and the regulating member 84 are in contact with each other between the first intake side rocker arm 71 and the second intake side rocker arm 72. It is located at a position corresponding to between the second intake-side rocker arm 72 and the third intake-side rocker arm 72. Therefore, the rocker arms 71 to 73 are in a state of being capable of relative angular displacement with respect to each other, and the first rotation of the camshaft 19 'causes
The intake-side rocker arm 71 swings in response to the sliding contact with the first intake-side opening / closing operation cam 74, and one intake valve V _I1 has the timing and lift amount according to the shape of the first intake-side opening / closing operation cam 74. Open and close with. Further, the third intake-side rocker arm 73 which is in sliding contact with the minute actuation cam 76 is substantially in a rest state,
The other intake valve V _I2 can be substantially deactivated.
Further, the second intake side rocker arm 72 swings in response to the sliding contact with the second intake side opening / closing operation cam 75, but the swinging operation has no influence on the first and third intake side rocker arms 71, 73. Does not reach. Further, the exhaust valves V _E1 and V _E2 are opened / closed at timings and lift amounts according to the shapes of the exhaust side opening / closing actuating cams 27, 27.

By the way, as shown in FIG. 10, the opening angle center timing θ _C2 of the minute lift curve C ₂ of the intake valve V _I2 by the minute operation cam 76 is determined by the intake valve V _I by the first intake side opening / closing operation cam 74.
The intake stroke on the retard side along the crank angle with respect to the opening angle central timing θ _C1 ′ in the valve opening lift curve C ₁ ′ of _I1 is set, preferably in the range of 130 to 180 degrees from the intake stroke start TDC. Moreover, the closing timing θ _VC of the intake valve V _I2 slightly opened by the minute actuation cam 76 is determined by the crank angle in the valve opening lift curve C ₁ ′ of the intake valve V _I1 by the first intake side opening / closing actuation cam 74. It is set at a portion corresponding to the buffer curve portion C _1S ′ at the end portion along the line.

When a high hydraulic pressure is applied to the hydraulic chamber 86 mainly in the high-speed rotation range of the engine, the connecting piston 82 moves in a direction of increasing the volume of the hydraulic chamber 86 against the spring force of the return spring 85 while pressing the connecting pin 83. When the axes of the connecting piston 82, the connecting pin 83, and the regulating member 84 are aligned with each other, that is, when the intake-side rocker arms 71 to 73 enter the stationary state, the connecting piston 82 is fitted to the second intake-side rocker arm 72. Then, the connecting pin 33 is fitted into the first intake-side rocker arm 73 accordingly, whereby the intake-side rocker arms 71 to 73 are brought into a connected state. Therefore, the first and third intake-side rocker arms 71 and 73 swing together with the second intake-side rocker arm 72 that is in sliding contact with the second intake-side opening / closing operation cam 75, and both intake valves V _I1 and V _I2
Is a timing and a lift amount according to the shape of the second intake side opening / closing operation cam 75, and is opened / closed as shown by the valve opening lift curve C ₃ in FIG. Both exhaust side rocker arms 22 and 23 are connected to the exhaust side opening / closing operation cam 2 as in the low speed operation range.
Both exhaust valves V _E1 and V _E2 are opened and closed at the timing and lift amount according to the shape of 7,27.

Even in an internal combustion engine equipped with such a valve operating device 18 ', the same effects as those of the above-described embodiment can be obtained by performing the same control as that of the embodiment shown in FIGS. 1 to 7.

C. Effects of the Invention As described above, according to the inventions of the claims, in the intake stroke mainly in the low-speed operation range of the engine, the minute cam is used to delay the local movement of the intake valve which is opened and closed by the opening / closing operation cam. Since the intake valve is slightly opened, the adverse effect of swirl generation caused by a slight opening operation of the local intake valve on the swirl generation can be eliminated and the combustibility can be improved. Even if the valve operation characteristic switching means fails to switch the valve operation characteristic and the other intake valve operates in the valve opening direction up to a relatively high lift and then reverses in the valve closing direction, the intake valve is controlled by the minute operation cam. It is possible to effectively prevent the impact sound from being generated by avoiding the direct collision with the valve seat.

Moreover, since the fuel injection end timing is set to the first half of the intake stroke in which the other intake valve is almost not opened, the other intake valve is operated in a favorable manner in spite of the slight opening operation as described above. Stratified air supply is achieved, and torque fluctuations can be suppressed.

Further, according to the invention of claim 2, the maximum lift portion of the minute lift curve by the cam for minute operation is set to the rear side along the crank angle with respect to the maximum lift portion of the valve lift curve by the cam for opening / closing operation. It becomes possible to more effectively avoid the swirl generation inhibition when the other intake valve is slightly opened.

[Brief description of drawings]

1 to 7 show an embodiment of the present invention. FIG. 1 is an overall configuration diagram, FIG. 2 is an enlarged plan view of a partial notch along line II-II of FIG. FIG. 3 is a diagram showing the relationship between the intake valve operating state and the fuel injection timing, FIG. 4 is a graph showing the experimental results of the influence of the fuel injection timing on the combustion stability, and FIG. 5 is the torque fluctuation at the fuel injection end timing. Fig. 6 is a graph showing the experimental result of the effect on the combustion rate, Fig. 6 is a graph showing the experimental result of the effect on the combustion limit due to the difference in the opening angle center timing of the intake valve in the substantially resting state, and Fig. 7 is the substantially resting state. FIG. 8 to FIG. 10 are graphs showing the experimental results of the influences on the torque fluctuation rate, the fuel consumption, and the exhaust gas properties due to the difference in the opening center timing of a certain intake valve, and FIGS. 8 to 10 show another embodiment of the present invention. FIG. 8 is a vertical cross-sectional view of the valve gear, which is a cross-sectional view taken along the line VIII-VIII in FIG. Figure 9 sectional view taken along line IX-IX of Figure 8, Figure 10 is a diagram showing the relationship between the intake valve operating state and the fuel injection timing. 18,18 ′ …… Valve operating device, 19,19 ′ …… Camshaft, 20,2
1; 71,72,73 …… Intake side rocker arm as valve drive member, 25,74,75 …… Cam for opening / closing operation, 26,76 …… Cam for minute operation, 35,35 ′ …… Switching valve operation characteristics means, 55 ...... fuel injection valve, C _1, C ₁ '...... opening lift curve, C _1M, C _2M ...... maximum lift unit, C _1S, C _1S' ...... buffer curve portion, C ₂ ...... minute Lift curve, V _I1 , V _I2 …… Intake valve, θ _C1 , θ _C1 ′, θ _C2 …… Open angle center timing, θ _FE …… Fuel injection end timing, θ _VC …… End timing

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location F02D 41/34 F 9247-3G (56) References JP-A-63-124817 (JP, A) Special features Kai 62-288305 (JP, A) JP 64-80735 (JP, A)

Claims (3)

[Claims] Claims: 1. An opening / closing actuating cam (25, 25) for opening and closing one intake valve (V _I1 ) of a pair of intake valves (V _I1 , V ₁₂ ) mainly in an intake stroke in a low speed operation range of an engine. 74), as well as a plurality of cams (25,26; 74,75) including a micro-actuating cam (26,76) for opening the other intake valve (V _I2 ) by a minute amount to put it into a substantially resting state. , 76) provided with a camshaft (19, 19 '), the operating characteristics of both intake valves (V _I1 , V _I2 ) depend on the operating condition of the engine. A switchable valve operating characteristic switching means (35, 35 ') is provided, and a fuel injection valve (55) for injecting fuel in an intake stroke to an intake system connected to the pair of intake valves (V _I1 , V _I2 ) is provided. In the internal combustion engine, the minute actuation cams (26, 76) are used to open and close one intake valve (V _I1 ) mainly by the opening / closing actuation cams (25, 74) in the low speed operation range of the engine. Open angle center timing (θ _C2 ) on the retard side of the lift curve (C ₁ , C ₁ ′) open angle central timing (θ _C1 , θ _C1 ′)
And a minute lift curve (C ₂ ) having an end time (θ _VC ) in the vicinity of a buffer curve part (C _1S , C _1S ′) at the end along the crank angle of the valve opening lift curve (C ₁ , C ₁ ′). ) Is formed to open the other intake valve (V _I2 ), and the fuel injection of the fuel injection valve (55) is completed in the operating state in which only the one intake valve (V _I1 ) is substantially opened and closed. An internal combustion engine characterized in that the timing (θ _EF ) is set in the first half of the intake stroke. _2. The maximum lift portion (C _2M ) of the minute lift curve (C ₂ ) formed by the minute operation cams (26, 76) is the valve opening lift curve (C ₁ , 'maximum lift portion (C _1M, C _1M) of') an internal combustion engine as in claim claim, wherein the set to the rear side along the crank angle than C _1. 3. The valve operating device (18, 18 ') includes a camshaft (1
9,19 ') cams (25,26; 74,75,76) and a plurality of valve drive members (20,21;) provided adjacent to each other between the pair of intake valves (V _I1 , V _I2 ). 71, 72, 73), and the valve operating characteristic switching means (35, 35 ') is provided with the adjacent valve driving members (20, 21; 71, 72, 7).
3) The internal combustion engine according to claim 1 or 2, which is configured to be switchable between mutual connection and disconnection.