JPH0811935B2 - Intake control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Field of Industrial Application The present invention relates to a valve gear having a valve operating characteristic switching means capable of switching the operating characteristic of an engine valve, and mainly to a low speed rotation of an engine. The present invention relates to an intake control device for an internal combustion engine, comprising: a control means for controlling the operation of the valve operation characteristic switching means for switching control of the valve operation characteristic of an engine valve between a control range and a high speed rotation range of an engine.

(2) Conventional Technology Conventionally, such an internal combustion engine is disclosed in, for example, Japanese Patent Laid-Open No. 61-19926.
It is known from Japanese Patent Publication No.

(3) Problems to be Solved by the Invention By the way, in the above-mentioned conventional one, an operating characteristic capable of reducing fuel consumption mainly in the low speed rotation range of the engine, and an operating characteristic capable of achieving high output mainly in the high speed rotation range of the engine. In order to open and close the engine valve, the valve operating characteristic switching means switches the operating characteristic of the engine valve. However, at the time of switching to the valve operating characteristic, switching shock occurs due to the difference in the output torque of the engine. Therefore, in order to absorb the shock, retard control of ignition timing is performed, but fuel consumption is deteriorated by that amount.

On the other hand, an internal combustion engine for a vehicle uses resonance supercharging in the low speed rotation range of the engine and inertial supercharging in the high speed rotation range to output torque characteristics having output peaks in the low speed rotation range and the high speed rotation range, respectively. It is common to have
If the air chamber is branched from the intake passage between the air cleaner and the throttle valve, the resonance effect of the air chamber causes the output peak due to resonance supercharging, which occurs when the air chamber is not provided, to be slower. It is known to be divided into an output peak on the side of the engine and an output peak on the side of higher speeds.If the air chamber is connected to the intake passage only in the medium speed range of the engine, the output torque in the medium speed range It is possible to avoid depression. Moreover, since there is a valley between the above-mentioned two output peaks, when the valve operating characteristic switching means is switched to operate at the portion corresponding to the valley, the difference in output torque due to the switching can be reduced.

The present invention has been made in view of such circumstances,
The torque step at the time of switching the valve operating characteristics by the valve operating characteristic switching means is minimized by utilizing the resonance effect of the branch air chamber,
An object of the present invention is to provide an intake control device for an internal combustion engine that can suppress an increase in fuel consumption due to ignition timing retard.

B. Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, according to the present invention, the control means closes the control valve in the low speed rotation range of the engine, The output torque difference between the engine before and after switching the valve operating characteristics is controlled when the valve is opened in the speed range and closed in the high speed range of the engine so that the valve is switched from the low speed range to the medium speed range. In order to reduce the switching shock caused by, the valve operating characteristic switching means is switched and controlled after the valve opening operation of the control valve and during the valve opening period until the engine speed reaches a predetermined value.

(2) Operation According to the above configuration, in the medium speed range of the engine, the output torque of the engine can be increased by the resonance effect of the air chamber when the control valve is opened.

Moreover, the output torque in the medium speed range obtained based on the special provision of the air chamber (opening of the control valve) is after the opening operation of the control valve accompanying the transition from the low speed range of the engine to the medium speed range. Since the engine speed is relatively low during the valve opening period until the engine speed reaches a predetermined value, the output torque step due to the switching is minimized by switching the valve operating characteristics of the engine valve during the valve opening period. It becomes possible.

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

1 to 3 show an embodiment of the present invention. FIG. 1 is an overall configuration diagram, FIG. 2 is a partially cutaway plan view taken along line II-II of FIG. 1, and FIG. The figure is an output torque characteristic diagram.

First, in FIG. 1, a cylinder head 2 is connected to an upper surface of a cylinder block 1 and upper surfaces of a plurality of cylinders 3 provided in the cylinder block 1 are formed so as to constitute a main part of an engine body in a 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, and both intake valve openings 6 are located on one side surface of the cylinder head 2. Is connected to a single intake port 8 that is open to the outside, and both exhaust valve ports 7 are connected to a single exhaust port 9 that opens to the other side surface of the cylinder head 2.
Connected to. Further, the intake valves V _I1 and V _I2 as a pair of engine valves capable of individually opening and closing both intake valve ports 6 are slidably fitted to a pair of guide cylinders 10 arranged in the cylinder head 2. Each intake valve V _I1 , V protruding from each guide cylinder 10.
Coil-shaped valve springs 13 surrounding the intake valves V _I1 and V _I2 are provided between the retainer 12 fixed to the upper end of _I2 and the cylinder head 2, respectively. 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 ports 7 are slidably fitted to a pair of guide cylinders 11 arranged on the cylinder head 2, respectively. Between the retainer 14 fixed to the upper ends of the exhaust valves V _E1 and V _E2 protruding from the cylinder 11 and the cylinder head 2, there are coiled valve springs 15 surrounding the exhaust valves V _E1 and V _E2. The exhaust valves V _E1 , V _E1 ,
V _E2 is biased upward, that is, in the valve closing direction.

Referring also to FIG. ₂ , a valve train 16 is connected to both intake valves V _I1 and V _I2 and both exhaust valves V _E1 and V _E2 . This valve operating device 16 operates by rotating a single camshaft 17 linked with a crankshaft (not shown) at a speed reduction ratio of 1/2 and rotating the camshaft 17 to open and close both intake valves V _I1 and V _I2 . First and second intake-side rocker arms 18, 19 for conversion into
And the rotational movement of the camshaft 17 is controlled by both exhaust valves V _E1 , V _E2
And the first and second exhaust side rocker arms 20 and 21 for converting into the opening and closing movements of the.

The camshaft 17 includes a cylinder head 2 and holders 22 respectively coupled to the cylinder head 2 on both sides of the cylinder 3 along the axis of the crankshaft, and has a horizontal axis perpendicular to the axis of the cylinder 3. While being rotatably supported.

The camshaft 17 includes an intake side cam 23 and the intake side cam 23.
The raised portion 24 adjacently disposed on one side of the 23 is integrally provided, and the exhaust side cams 25, 25 are integrally provided on both sides of the intake side cam 23 and the raised portion 24. The raised portion 24 basically has a circular outer surface centered on the axis of the camshaft 19 so that one of the intake valves V _I1 and V _I2 , V _I2, is substantially at rest in the low speed operation region of the engine. Although it is formed so as to have, a slightly protruding projection is provided at a position corresponding to the high position of the intake cam 23. Moreover, the camshaft
The width of the raised portion 24 in the direction along the axis of 17 is set to be relatively narrow.

First intake-side rocker arm 18 in one of the intake valves V _I1 is linked, coupled, on the other intake valve V _I2 is the second intake-side rocker arm 19 interlocked, are connected, the intake-side rocker arms 18, 1
9 is a position diagonally above the camshaft 17
An intake side rocker shaft 26 fixedly supported by a holder 22 while having an axis parallel to 7 is swingably supported.
Both exhaust side rocker arms 20 and 21 are individually interlocked and connected to both exhaust valves V _E1 and V _E2 , and are arranged in a holder 22 in a position diagonally above the cam shaft 17 in parallel with the intake side rocker shaft 26. Exhaust rocker shaft 27 fixedly supported
It is rockably supported by.

A roller 28, which is in sliding contact with the intake cam 23, is pivotally supported at one end of the first intake rocker arm 18, and a second intake rocker arm is provided.
A slide contact portion 29, which is in sliding contact with the raised portion 24, is provided at one end of the 19 while narrowing the width corresponding to the raised portion 24. A roller 30 slidably contacting the exhaust side cams 25, 25 is pivotally supported at one end of each of the exhaust side rocker arms 20, 21.

The other end of each of the first and second intake-side rocker arms 18 and 19 is provided with a tappet screw 31 that comes into contact with the upper ends of both 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 18 and 19. Also, both exhaust side rocker arms 20,21
A tappet screw 32 that abuts on the upper ends of the exhaust valves V _E1 and V _E2 is screwed to the other end of the exhaust valve V _E1 and V _{E2 so that} the exhaust valves V _E1 and V _E2 can move back and forth. V _E1,, V
_E2 will open and close.

In order to switch the operating characteristics of both 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, the intake side rocker arms 18 and 19 are provided on both intake side rocker arms 18 and 19. Connected state, both intake side rocker arm 18,
A valve operating characteristic switching means 35 capable of switching the connection release state of 19 is provided.

This valve operating characteristic switching means 35 is provided on both intake side rocker arms.
Connection piston 36 that can connect 18, 19 and connection piston 36
And a return spring 38 for urging the connecting piston 36 and the restricting member 37 toward the decoupling side.

The connecting piston 36 is slidable on the first intake-side rocker arm 18 while defining a hydraulic chamber 39 between one end thereof and the first intake-side rocker arm 18 so as to be movable in the axial direction parallel to the intake-side rocker shaft 26. 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 18, and the communication passage 40, that is, the communication passage 40, is formed in the intake-side rocker shaft 26 regardless of the swinging state of the first intake-side rocker arm 18. An oil passage 41 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 19.
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 19 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 actuation characteristic switching means 35, the solenoid valve 42 for switching connection is mainly used to control the hydraulic chamber when the engine is operating at a low speed.
The hydraulic pressure of 39 is released, and the spring force of the return spring 38 causes the contact surfaces of the connecting piston 36 and the regulating member 37 to be located between the first and second intake-side rocker arms 18 and 19. Therefore, both intake side rocker arms 18 and 19 are in a state in which they can be displaced relative to each other, and the rotation operation of the cam shaft 17 causes the first intake side rocker arm 18 to swing in accordance with the sliding contact with the intake side cam 23. Intake valve V _I1 of intake side cam 23
It opens and closes at the timing and lift according to the shape of. In addition, the second intake side rocker arm 19 slidingly contacting the raised portion 24
Becomes substantially inactive, and the other intake valve V _I2 can be substantially inactive. Moreover, the intake valve V _I2 does not completely rest, but when one intake valve V _I1 opens, it operates slightly in the opening direction, so the intake valve V _I2 that occurs when the valve is completely closed. Can be prevented from sticking to the valve seat and fuel can be prevented from staying. Further exhaust valve V _E1 ,
V _E2 opens and closes at the timing and lift amount according to the shape of the intake side cams 25, 25.

Mainly for high speed operation of the engine Electromagnetic control valve for connection switching
42 is opened, and high hydraulic pressure is applied to the hydraulic chamber 39. This causes the connecting piston 36 to resist the spring force of the return spring 38 and
When the axes of the connecting piston 36 and the regulating member 37 are aligned, that is, when both intake side rocker arms 18 and 19 enter the stationary state, the connecting piston 36 moves toward the second intake side. It fits on the rocker arm 19,
Both intake-side rocker arms 18 and 19 are in a connected state, and the second intake-side rocker arm 19 swings together with the first intake-side rocker arm 18 that is in sliding contact with the intake-side cam 23, so that both intake valves V _I1 , V
_I2 is opened / closed at a timing and a lift amount according to the shape of the intake side cam 23. Further, the quantity exhaust side rocker arms 20 and 21 have both exhaust valves V _E1 and V _E2 at the timing and lift amount according to the shape of the exhaust side cams 25 and 25 as in the low speed operation.
Open and close.

The cylinder head 2 has rocker arms 20 and 21 on both exhaust sides.
A plug cylinder portion 44 is provided so as to incline sideways as it goes upward between them, and the ignition plug 45 inserted from this plug cylinder portion 44 faces the center of the upper portion of the combustion chamber 5 in the cylinder head 2. Mounted.

An air cleaner 49 is connected to the intake port 8 via an intake manifold 46 and a throttle body 48 having a throttle valve 47. The intake manifold 46 and the throttle are connected between the air cleaner 49 and the intake port 8. An intake passage 50 is formed in the body 48. Thus, in the intake passage 50, a bypass passage 51 and a fast idle passage 52 are connected in parallel bypassing the throttle valve 47, and the bypass passage 51 is provided with a bypass electromagnetic control valve 53. The first idle passage 52 is provided with a wax valve 54 which operates according to the temperature of the cooling water of the engine body.

At the end of the intake manifold 46 on the cylinder head 2 side, a fuel injection valve 55 is attached from the intake port 8 toward both intake valve openings 6, and a fuel supply source 56 is attached to the fuel injection valve 55.
Is connected.

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 type 59 and the idle adjusting screw 60.

From the intake passage 50 between the throttle valve 47 and the air cleaner 49, a branch passage 62 having a control valve 61 that can be opened and closed is branched, and the branch passage 62 is connected to a resonance box 64 forming an air chamber 63. A negative pressure type actuator 65 for opening the control valve 61 when a negative pressure is applied is connected to the control valve 61, and the negative pressure type actuator 65 is connected to the intake passage downstream of the throttle valve 47. 50 is connected via a control valve switching electromagnetic control valve 66.

By the way, the branch path 62 and the air chamber 63 as described above are
Since the resonance effect of the air chamber 63 is exhibited when the control valve 61 is opened, it is provided in order to increase the filling efficiency due to the resonance effect. On the other hand, the intake path 50
Uses resonance supercharging in the low speed revolution range of the engine and utilizes inertial supercharging in the high speed revolution range of the engine to obtain output torque characteristics having peaks in the low speed range and high speed range of the engine. The output torque can be increased by the resonance effect of the air chamber 63 only between the two peaks of the output torque, that is, in the medium speed rotation range of the engine, and the other rotation speeds In the region, it is counterproductive to cause the air chamber 63 to exhibit a resonance effect.

Electromagnetic control valve 42 for switching the connection, electromagnetic control valve for bypass
The operation of the fuel injection valve 53, the fuel injection valve 55, the electromagnetic air amount control valve 59, and the control valve switching electromagnetic control valve 66 is controlled by a control means 67 composed of a computer. The intake pressure P _B detected by the sensor 68, the cooling water temperature T _W detected by the engine cooling water temperature sensor 69, and the engine speed N _E detected by the rotation speed sensor 90 are input.

Thus, the control means 67 controls the engine to operate in the low speed rotation range (for example,
650 to 2400 rpm), the control valve 61 is closed, when the engine is in the medium speed range (for example, 2400 to 3400 rpm), the control valve 61 is opened, and the engine is in the high speed range (for example, 3400 rpm).
The operation of the control valve switching electromagnetic control valve 66 is controlled so that the control valve 61 is closed when the speed is within the rpm range. Also control means
When the engine is mainly in the low speed rotation range, 67 decouples both intake side rocker arms 18 and 19 so as to substantially stop one of the intake valves V _I1 and V _I2 V _I2 , and the engine mainly rotates at high speed. Intake valves V _I1 , V _I2 when in range
In order to open and close the intake side cam 23 by the intake side cam 23, the operation of the valve operation characteristic switching means 35 is controlled so that both intake side rocker arms 18, 19 are connected, and the control valve 61 is opened. The valve operating characteristic switching means 35 is set to perform the switching operation in the rotation range, that is, the medium speed rotation range.

Next, the operation of this embodiment will be described with reference to FIG. 3. With the control valve 61 closed, the valve operating characteristic switching means 35 of the valve operating device 16 causes the operating characteristics of both intake valves V _I1 and V _I2 . When is switched, as shown by the broken line in FIG.
A relatively large torque step d ₁ occurs in the medium speed range of the engine,
As a result, a comparatively large switching shock occurs.

However, the intake valve V _I1 , V
_When the operating characteristic of _I2 is set mainly for the high speed rotation range, and the control valve 61 is controlled in the order of closing, opening and closing as the engine speed increases, it is shown by the chain line in FIG. As described above, the output peak can be generated in the medium speed rotation range in which the control valve 61 is opened. Thus the control valve
Until the engine speed increases by a predetermined value after switching 61 from the valve closed state to the valve open state, the output torque becomes lower than the output torque when the branched air chamber 63 is not provided. Both intake valves by means of valve operating characteristic switching means 35
By switching the operating characteristics of V _I1 and V _I2 , the output torque as a whole can be made to be as shown by the solid line in FIG. 3, and the torque step during the switching operation of the valve operating characteristic switching means 35 can be changed.
It is possible to keep d ₂ relatively small. Therefore, the switching shock can be suppressed to a small value, the retard of the ignition timing for absorbing the switching shock is unnecessary, or the retard value can be reduced, and the increase in fuel consumption due to the retard can be suppressed.

4 and 5 show a modified example of the valve operating device, and the same reference numerals are given to the portions corresponding to the above-described embodiments.

The valve operating device 16 'includes a camshaft 17' and first, second and third intake side rocker arms for converting rotational movement of the camshaft 17 'into opening / closing movements of both intake valves V _I1 , V _I2.
71, 72, 73 and first and second for converting the rotational movement of the camshaft 17 'into the opening / closing movement of the exhaust valves V _E1 , V _E2 .
Exhaust side rocker arms 20 and 21 are provided.

On the camshaft 17 ', a first intake side cam 74 having a shape corresponding to the low speed operation of the engine and a first intake side cam 74 having a shape corresponding to the high speed operation of the engine are disposed adjacent to one side of the first intake side cam 74. The second intake cam 75 and the raised portion 76 adjacent to one side of the second intake cam 75 are integrally provided, and
Exhaust side cams 25, 25 on both sides of intake side cam 74 and ridge 76
Are provided integrally.

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 26.
It is rockably supported by. Also, the first and second exhaust side rocker arms that are linked and connected to both exhaust valves V _E1 and V _E2 individually
20, 21 are swingably supported by the exhaust side rocker shaft 27.

A first intake side cam is provided at one end of the first intake side rocker arm 71.
A roller 77 slidingly contacting the 74 is pivotally supported, one end of the third intake side rocker arm 73 is slidably contacting the raised portion 76, and the second intake side rocker arm 72 is slidably contacting the second intake side cam 75. A roller 30 slidably contacting the exhaust side cams 25, 25 is pivotally supported at one end of each of the exhaust side rocker arms 20, 21.

By the way, a support plate 78 is fixedly provided on the upper end of the holder 22, and the support plate 78 is elastically moved in a direction in which the second intake-side rocker arm 72 is slidably contacted with the second intake-side cam 75 of the camshaft 17 '. A lost motion mechanism 79 for urging and urging is arranged.

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, A restricting member 84 that restricts the movement of the connecting pin 83, and a return spring that biases the connecting piston 82, the connecting pin 83, and the restricting member 84 toward the disconnecting side.
With 85.

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 26, 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 26 is defined. A connecting pin 83, one end of which abuts against the other end of the connecting piston 22, 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 26. Further, a 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 arm 26, and a return 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 73. Therefore, the rocker arms 71 to 73 are in a state in which they can be angularly displaced relative to each other, and when the camshaft 17 'is rotated, the first
The intake-side rocker arm 71 swings in response to the sliding contact with the first intake-side cam 74, and one intake valve V _I1 opens and closes at the timing and lift amount corresponding to the shape of the first intake-side cam 74.
Further, the third intake-side rocker arm 73 is brought into a substantially rest state by slidingly contacting the raised portion 76, and the other intake valve V _I2 can be substantially _rested . In addition, the second intake side rocker arm
Although 72 swings in accordance with the sliding contact with the second intake side cam 75, the swinging action is performed by the first and third intake side rocker arms 71, 73.
It has no effect on. 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 cams 20 and 21.

When a high hydraulic pressure is applied to the hydraulic chamber 86 mainly in the high-speed rotation region 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, 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 to 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 second sliding contact with the second intake side cam 75
The first and third intake-side rocker arms 71 and 73 swing together with the intake-side rocker arm 72, and both intake valves V _I1 and V _I2 are opened and closed at the timing and lift amount according to the shape of the second intake-side cam 75. . Also, both exhaust side rocker arms 20,21
Opens and closes both exhaust valves V _E1 and V _E2 at the timing and lift amount according to the shape of the exhaust side cams 25, 25 as in the low speed operation range.

Even in an internal combustion engine equipped with such a valve operating device 16 ', the torque during switching operation by the valve operating characteristic switching means 35' is performed by performing intake control similar to that of the embodiment shown in FIGS. It is possible to reduce the step and suppress the switching shock due to the torque step.

Also in FIGS. 4 and 5, the camshaft 17 '
A cam having a shape corresponding to the low speed operation of the engine may be provided instead of the raised portion 76 provided in.

C. Effects of the Invention As described above, according to the present invention, the control means closes the control valve in the low speed rotation range of the engine, opens it in the medium speed rotation range of the engine, and closes it in the high speed rotation range of the engine. Since the switching control is performed as much as possible, the output torque can be increased in the middle rotation range of the engine due to the resonance effect of the air chamber when the control valve is opened.

In addition, the output torque in the medium speed range obtained based on the special provision of this air chamber (opening of the control valve) causes the output torque in the middle speed range to change from the low speed range to the middle speed range after the control valve opens. In addition, in view of the fact that the engine speed is relatively low during opening of the engine until the engine speed reaches the prescribed value, when the engine shifts from the low speed rotation range to the medium speed rotation range, the valve operation characteristic switching is performed during the period. Since the means is switched and controlled, the output torque step of the engine accompanying the switching of the valve operating characteristics can be minimized, and the switching shock can be reduced.
Since it is not necessary to significantly retard the ignition timing in order to reduce the switching shock, fuel consumption can be reduced.

[Brief description of drawings]

1 to 3 show an embodiment of the present invention. FIG. 1 is an overall configuration diagram, FIG. 2 is a partially cutaway plan view taken along line II-II of FIG. 1, and FIG. The figure shows the output torque characteristic diagram,
4 and 5 show a modified example of the valve train, and FIG. 4 is a vertical sectional side view taken along the line IV-IV in FIG.
The drawing is a sectional view taken along line VV of FIG. 16,16 ′ …… Valve device, 35,35 ′ …… Valve operating characteristic switching means, 47 …… Throttle valve, 49 …… Air cleaner, 50 ……
Intake passage, 61 ... Control valve, 63 ... Air chamber, 67 ... Control means, V _I1 , V _I2 ... Intake valve as engine valve

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location F02D 43/00 301 Z (72) Inventor Tomoya Abe 1-4-1 Chuo, Wako, Saitama Stock Incorporated in Honda R & D Co., Ltd. (72) Inventor Kazutoshi Nishizawa 1-4-1 Chuo, Wako-shi, Saitama Incorporated in Honda R & D Co., Ltd. (56) Reference JP 1-182525 (JP, A) Showa 59-148438 (JP, U) Jikkouhei 3-20496 (JP, Y2)

Claims (1)

[Claims] 1. A valve train (1) having valve operating characteristic switching means (35, 35 ') capable of switching operating characteristics of engine valves (V _I1 , V _I2 ).
6, 16 '), and the operation of the valve operation characteristic switching means (35, 35') is controlled to switch and control the valve operation characteristics of the engine valve mainly between the low speed rotation range of the engine and the high speed rotation range of the engine. In an internal combustion engine including a control means (67), an air chamber (63) is branched from an intake passage (50) between an air cleaner (49) and a throttle valve (47) via a control valve (61) that can be opened and closed, The control means (67) controls the switching of the control valve (61) such that the control valve (61) is closed in a low speed rotation range of the engine, opened in a middle speed rotation range of the engine, and closed in a high speed rotation range of the engine. When the engine shifts from the low speed rotation range to the medium speed range, after the opening operation of the control valve (61) and to reduce the switching shock due to the output torque difference of the engine before and after the switching of the valve operating characteristics, The valve operating characteristic switching means during the valve opening period until the engine speed reaches a predetermined value. Characterized by switching control 35, 35 '), the intake control device of an internal combustion engine.