JPH07102920A - Valve timing control device for engine - Google Patents

Abstract

PURPOSE:To supply proper air into a combustion chamber according to operating condition in an intake three valve type engine. CONSTITUTION:In an intake three valve type engine CE, second and third intake valves 2, 3 are closed at all times at the time of low speed, only a first intake valve 1 is driven with small lift amount, and strong swirl is generated by air which flows from a first intake port 4 into a combustion chamber 7 so as to improve ignition performance. At the time of intermediate speed, the first to third intake valves 1 to 3 are driven with a small lift amount so as to improve both swirl and filling efficiency, and improve ignition performance, and also enough engine output is ensured in an intermediate speed range. At the time of high speed, the first to third intake valves 1 to 3 are driven with a large lift amount so as to improve filling efficiency to much extent, and also generate high output in an engine. It is thus possible to supply air which is suitable in operating condition so as to improve various kinds of performances in the engine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine valve timing control device.

[0002]

2. Description of the Related Art Generally, an engine is provided with a valve operating mechanism that opens and closes valve operating valves (intake valve and exhaust valve) at a predetermined timing synchronized with rotation of a crankshaft. Then, in the engine provided with such a valve operating mechanism, the appropriate opening / closing timing of the intake valve or the valve lift amount changes according to the operating state of the engine, for example, the engine load, the engine speed, and the like. Therefore, in recent years, an engine provided with a valve timing control device capable of changing the valve opening / closing timing or the valve lift amount according to the operating state has been proposed.

Generally, in an engine, at high speed
It is required to improve the charging efficiency, that is, the engine output at the time of high rotation or at the time of high load, and to improve the ignitability / combustibility of the air-fuel mixture at the time of low speed (at the time of low rotation) or at the low load.

Therefore, for example, a valve timing control device is provided so that the valve lift amount of the intake valve can be switched between large and small levels, and at the time of high speed, the valve lift amount is increased so that air easily enters the combustion chamber. Then, while increasing the charging efficiency to improve the engine output, the valve lift amount is reduced at low speed to increase the flow velocity of the air flowing into the combustion chamber, and swirls are generated in the combustion chamber to stratify the air-fuel mixture, An engine has been proposed in which the ignitability and combustibility of an air-fuel mixture are enhanced (for example, Japanese Patent Laid-Open No. 63-11
7109).

More specifically, in an intake two-valve engine having two intake valves in each cylinder, the valve lifts of both intake valves can be integrally switched, and then the valves of both intake valves can be changed. It has been proposed that the lift amount be reduced at low speeds and increased at high speeds. In addition, in the intake two-valve engine, the valve lift amount of each intake valve can be individually switched, and then the first
Of the intake valve of the second intake valve is switched to 0 (normally closed) or a large lift amount, and the valve lift amount of the second intake valve is switched to a small lift amount or a large lift amount. The intake valve is always closed while the valve lift amount of the second intake valve is set to a small lift amount to strengthen the swirl, and at high speeds, the valve lift amount of both intake valves is set to a large lift amount to increase the filling efficiency. Things have been proposed.

[0006]

However, in the conventional engine equipped with such a valve timing control device, since the lift characteristics are only switched in two stages of low speed and high speed, the engine is not always changed. It is not possible to supply the air that is suitable for the operating conditions.
Further, only by switching the valve lift amount in this way, there are naturally limits to the effect of improving the charging efficiency at high speed and the effect of improving the ignitability / combustibility at low speed.

Therefore, an intake three-valve engine has been proposed in which each cylinder is provided with three intake ports which are opened and closed by an intake valve so that the charging efficiency can be effectively increased at high speed (for example, an actual engine). Kaisho 62-154210
(See Japanese Patent Publication). In such an intake three-valve engine,
In addition to the above-mentioned effect of improving the charging efficiency, the inflow characteristics of air into the combustion chamber can be finely changed by closing some intake valves at all times, so it is basically also effective for generating swirls. Is considered to be. Further, since each intake valve is lightened, there is an advantage that the engine rotation limit can be increased.

However, the intake three-valve engine equipped with a valve timing control device capable of switching the valve lift amount of the intake valve supplies more appropriate air than the conventional one according to the operating condition such as the engine speed. There is no specific control method or control means that can perform the above.

The present invention has been made to solve the above-mentioned conventional problems, and it is possible to supply air to the intake three-valve engine by the combustion chamber in a rational manner in accordance with the operating condition. An object is to provide a valve timing control device.

[0010]

In order to achieve the above object, a first invention is a valve timing control device for an intake three-valve engine in which first to third intake valves are provided in one cylinder. , One of a first lift characteristic that lifts the first intake valve to a first lift amount at the valve opening timing, and a second lift characteristic that lifts the first intake valve to a second lift amount at the valve opening timing. While driving the first intake valve driving means that can be driven and the second and third intake valves in synchronization with each other, both intake valves can be normally closed, and each of them can be opened at the opening timing. Second intake characteristic that can be driven by either one of the first lift characteristic that lifts up to the first lift amount and the second lift characteristic that lifts up to the respective second lift amount at the valve opening timing. The valve drive means and the second and third intake valves at low speed In the closed state, the first intake valve is driven with the first lift characteristic at the middle speed, the second and third intake valves are driven with the first lift characteristic, and the first intake valve and the second intake valve are driven at the high speed. In order to prevent at least one of the third intake valves from being driven by their respective second lift characteristics and the second and third intake valves from being in the normally closed state,
An intake valve control means for controlling a second intake valve drive means is provided, and a valve timing control device for an engine is provided.

According to a second aspect of the invention, in the engine valve timing control device according to the first aspect of the invention, in the first intake valve, the first lift amount is a small lift amount and the second lift amount is a large lift amount. A valve timing control device for an engine, characterized in that the first lift amount is a small lift amount and the second lift amount is a large lift amount in the second and third intake valves. I will provide a.

According to a third aspect of the invention, in the valve timing control device for an engine according to the first or second aspect, the first intake valve is disposed on the end side in a plan view when viewed in the intake valve arrangement direction. A valve timing control device for an engine is provided.

According to a fourth aspect of the present invention, in the engine valve timing control device according to the third aspect of the present invention, one of the second intake valve and the third intake valve which is located on the central side in the intake valve arrangement direction in plan view. A valve timing control device for an engine, wherein the first lift amount of the intake valve is larger than the first lift amount of the intake valve located on the end side.

[0014]

EXAMPLES Examples of the present invention will be specifically described below.
As shown in FIGS. 1 and 2, in one cylinder # 1 of an intake three-valve engine CE in which each cylinder (only one is shown) is provided with three intake valves and two exhaust valves, respectively. , Basically, when the first to third intake valves 1 to 3 are opened, the first
-The air-fuel mixture is sucked into the combustion chamber 7 through the third intake ports 4-6, and the air-fuel mixture is compressed by the piston (not shown) and then ignited and burned by the ignition plug 8 to generate the first and second air-fuel mixture.
Combustion gas (exhaust gas) is discharged to the first and second exhaust ports 11 and 12 when the exhaust valves 9 and 10 are opened.

Here, the first to third intake ports 4 to 6 and the first and second exhaust ports 11 and 12 are open to the ceiling of the combustion chamber 7, respectively. Then, in plan view, the openings (first to third intake valves 1 to 3) of the first to third intake ports 4 to 6 are the intake side half of the combustion chamber 7 (the right half in FIGS. 1 and 2). ),
The openings (first and second exhaust valves 9 and 10) of the first and second exhaust ports 11 and 12 are arranged in the exhaust side half of the combustion chamber 7 (the left half in FIGS. 1 and 2), and the ignition is performed. The plug 8 is arranged substantially in the center of the combustion chamber 7.

Hereinafter, the first to third intake valves 1 to 3 and the first,
A valve drive mechanism that drives the second exhaust valves 9 and 10 will be described. In the following, the intake valve and the exhaust valve may be collectively referred to as a valve. The first to third intake valves 1 to 3 are basically synchronized with the crankshaft (not shown) by the first to fourth intake cams 16 to 19 mounted on the intake camshaft 15 respectively. It is designed to be opened and closed at a predetermined timing. The intake camshaft 15 is rotatably supported by a plurality of intake bearings 20 (cylinder heads H). Here, the first to third intake valves 1 to
3 is the first to third return springs 21 to 23, respectively.
Is always urged in the valve closing direction (almost upward),
The first to third return springs 21 to 23 via the variable valve drive mechanism R by the predetermined intake side cams 16 to 19.
The valve is opened when the first to third intake valve stems 1a to 3a are pushed down against the biasing force of. The variable valve drive mechanism R is an assembly including the "first intake valve drive means" and the "second intake valve drive means" described in the claims.

On the other hand, the first and second exhaust valves 9 and 10 are respectively
The first and second exhaust side cams 26, 27 attached to the exhaust side cam shaft 25 are adapted to open and close at a predetermined timing synchronized with the crankshaft. In addition,
The exhaust side cam shaft 25 is rotatably supported by a plurality of exhaust side bearing portions 28 (cylinder heads H).
Here, the first and second exhaust valves 9 and 10 are normally urged in a valve closing direction (almost upward) by return springs (not shown), and are driven by predetermined exhaust side cams 26 and 27. Via the mechanism S, the valve is opened when the first and second exhaust valve stems 9a, 10a are pushed down against the urging force of the return spring.

Next, the variable valve drive mechanism R on the intake side and the valve drive mechanism S on the exhaust side will be described with reference to FIG. 3, but in the following, the direction A _{1 in} FIG. 3 is simply referred to as “front” for convenience. The A ₂ direction is simply referred to as “back”, the right direction in FIG. 3 is simply referred to as “right”, and the left direction in FIG. 3 is simply referred to as “left”. As shown in FIG. 3, the intake-side rocker arm shaft 31 is fixedly arranged in the intake-side half (right half) of the cylinder head H so that the axis of the intake-side rocker arm shaft 31 faces the front-rear direction (A ₁ , A ₂ directions). There is.

In the vicinity of cylinder # 1, the left end of the first intake rocker arm 32 is rotatably connected to the front portion of the intake rocker arm shaft 31, and the right end of the first intake rocker arm 32 is First intake valve stem 1a
Is always in contact with the upper end of the. Although not shown in detail, the middle portion of the first intake-side rocker arm 32 basically abuts on the cam surface of the second intake-side cam 17 and swings vertically by the second intake-side cam 17. It is supposed to be done. However, as will be described later, when the left end portion of the first link arm 34 is locked by the first lock member 35, the above contact does not occur, and the first intake side rocker arm 32 depends on the second intake side cam 17. I can't rock it. Here, the cam surface shape of the second intake-side cam 17 is such that when the second intake-side cam 17 pushes down the first intake-side rocker arm 32 as much as possible to open the first intake valve 1, The valve lift amount is set to be a predetermined small lift amount.

A first link arm 34 is arranged immediately in front of the first intake side rocker arm 32, and a right end portion of the first link arm 34 and a right end portion of the first intake side rocker arm 32 form a first connecting pin 33. Are linked together. The first intake-side rocker arm 32 and the first link arm 3
4 are rotatable around the first connecting pin 33, respectively. The left end of the first link arm 34 is connected to the first lock member 35. The first lock member 35 rotatably locks the left end portion of the first link arm 34 at a predetermined high position when hydraulic pressure is supplied from a hydraulic mechanism which will be described later, while when the hydraulic pressure is released. The left end portion is supported so as to be vertically movable.

The intermediate portion of the first link arm 34 is
Although not shown, the first intake side cam 16 is contacted to
The intake-side cam 16 is configured to swing in the vertical direction. Here, when the left end portion of the first link arm 34 is locked by the first lock member 35, the right end portion of the first link arm 34 swings in the vertical direction as the first intake cam 16 rotates. Then, along with this, the first intake-side rocker arm 32 swings up and down integrally with the first link arm 34. Here, the cam diameter of the first intake-side cam 16 is set larger than the cam diameter of the second intake-side cam 17, and the cam surface shape is the first
The intake side cam 16 swings the first link arm 34 downward to the maximum extent, and accordingly, the first intake side rocker arm 32
When the first intake valve 1 is opened by maximally rocking the valve, the valve lift amount of the first intake valve 1 is set to a predetermined large lift amount. That is, when hydraulic pressure is supplied to the first lock member 35 and the left end portion of the first link arm 34 is locked, the first intake valve 1 is opened and closed by the first intake side cam 16, and the valve lift amount thereof is large. Lift amount.

On the other hand, when the left end of the first link arm 34 is not locked by the first lock member 35,
As the first intake side cam 16 rotates, the first link arm 3
The left end of 4 swings up and down, and the right end does not particularly apply a force to the first intake side rocker arm 32 side. Therefore,
The first intake valve 1 is opened and closed by the second intake side cam 17,
The valve lift amount is a small lift amount.

In the vicinity of cylinder # 1, the left end of the second intake rocker arm 37 is rotatably connected to a portion of the intake rocker arm shaft 31 slightly rearward of the first intake rocker arm 32. The right end of the intake rocker arm 37 is always in contact with the upper end of the second intake valve stem 2a. The second intake-side rocker arm 37 cannot be vertically swung by any intake-side cam.

The second of the intake side rocker arm shaft 31
In the part slightly behind the intake side rocker arm 37, the third
The left end of the intake side rocker arm 38 is rotatably connected, and the right end of the third intake side rocker arm 38 is always in contact with the upper end of the third intake valve stem 3a. The third intake-side rocker arm 38 cannot be vertically swung by any intake-side cam.

The second link arm 40 is disposed immediately behind the third intake-side rocker arm 38, while the second link arm 40 is disposed on the second side.
Intake-side rocker arm 37 and third intake-side rocker arm 38
The third link arm 41 is arranged between the two. Here, the right end of the second intake side rocker arm 37, the right end of the third intake side rocker arm 38, and the second link arm 40.
And the right end of the third link arm 41 are connected to each other using the second connecting pin 39. It should be noted that all of these arms 37, 38, 40, 41 are rotatable around the second connecting pin 39.

The left end of the second link arm 40 is connected to the second lock member 42. The second lock member 42 is
Similar to the first lock member 35, when the hydraulic pressure is supplied, the left end of the second link arm 40 is locked, while when the hydraulic pressure is released, the left end is supported to be vertically movable. It has become. And the second
Although not shown, the intermediate portion of the link arm 40 abuts on the fourth intake-side cam 19 and is swingable in the vertical direction by the fourth intake-side cam 19. Here, when the left end portion of the second link arm 40 is locked, the right end portion of the second link arm 40 swings in the up-down direction as the fourth intake cam 19 rotates, and accordingly. The second and third intake-side rocker arms 37 and 38 swing vertically together with the second link arm 40.

Here, the cam surface shape of the fourth intake-side cam 19 causes the second link arm 40 to swing to the maximum downward, and accordingly, the second and third intake-side rocker arms 37,
38 by maximally oscillating downward so that the second and third intake valves 2, 3
When the valve is opened, the valve lift amounts of the second and third intake valves 2 and 3 are set to be a predetermined small lift amount. Therefore, when the hydraulic pressure is supplied to the second lock member 42 and the left end portion of the second link arm 40 is locked, the second and third intake valves 2, 3 are provided unless the third link arm 41 is locked. Is opened and closed by the fourth intake-side cam 19, and the valve lift amount becomes a small lift amount.

The left end of the third link arm 41 is connected to the third lock member 43. The third lock member 43 is
Similar to the second lock member 42, when the hydraulic pressure is supplied, the left end of the third link arm 41 is locked, and when the hydraulic pressure is released, the left end is supported so as to be vertically movable. It has become. And the third
Although not shown, the intermediate portion of the link arm 41 contacts the third intake-side cam 18 and is swingable in the vertical direction by the third intake-side cam 18. Here, when the left end portion of the third link arm 41 is locked, the right end portion of the third link arm 41 swings in the vertical direction as the third intake cam 18 rotates, and accordingly The second and third intake-side rocker arms 37 and 38 swing vertically together with the third link arm 41. In this case, the result does not change even if the left end portion of the second link arm 40 is locked by the second lock member 42.

Here, the cam diameter of the third intake-side cam 18 is set to be larger than the cam diameter of the fourth intake-side cam 19, and the cam surface shape is such that the third intake-side cam 18 is The 3rd link arm 41 is swung to the maximum downward, and accordingly, the 2nd and 3rd intake side rocker arms 37 and 38 are swung to the maximum downward to move the 2nd and 3rd intake valves 2 and 3. The valve lift amounts of the second and third intake valves 2 and 3 are set to a predetermined large lift amount when opened.

That is, when the hydraulic pressures of the second and third lock members 42 and 43 are released and the left end portions of the second and third link arms 40 and 41 are not locked, the second and third intake valves 2,
3 is normally closed, and when the hydraulic pressure is supplied only to the second lock member 42 and only the left end portion of the second link arm 40 is locked, the valve lift amounts of the second and third intake valves 2 and 3 are When the hydraulic pressure is supplied only to the third lock member 43 and only the left end portion of the third link arm 41 is locked, the valve lift amounts of the second and third intake valves 2 and 3 are large lift amounts. Becomes

On the other hand, an exhaust side rocker arm shaft 45 is fixedly arranged on the exhaust side half (left half) of the cylinder head H so that the axis of the rocker arm shaft 45 faces the front-rear direction (A ₁ , A ₂ direction). Then, in the vicinity of cylinder # 1, the right end portions of the first and second exhaust side rocker arms 46 and 47 are rotatably connected to the exhaust side rocker arm shaft 45, and the first and second exhaust side rocker arms 46 and 47, The left end of 47 is always in contact with the upper ends of the first and second exhaust valve stems 9a, 10a. Then, the first and second exhaust side rocker arms 46, 47
Although not shown in detail, the middle portion of the contact portion abuts on the cam surfaces of the first and second exhaust side cams 26 and 27 and is vertically swung by the first and second exhaust side cams 26 and 27. With this, the first and second exhaust valves 9 and 10 are opened and closed.

Hereinafter, the first to third locking members 35, 42, 4
A hydraulic mechanism that supplies and discharges hydraulic pressure to and from No. 3 will be described.
The first hydraulic passage 50 is connected to the first lock member 35,
A solenoid type hydraulic control valve 51 is provided in the first hydraulic passage 50.
Is installed. Here, the hydraulic control valve 51 controls supply and discharge of hydraulic pressure to and from the first lock member 35 in accordance with a control signal applied from a control unit C including a microcomputer.

A second hydraulic passage 52 is provided in the second lock member 42.
On the other hand, the third hydraulic passage 53 is connected to the third lock member 43. The upstream end of the second hydraulic passage 52 is connected to the first output port Y ₁ of the hydraulic switching device 54, and the upstream end of the third hydraulic passage 53 is connected to the second output port Y ₃ of the hydraulic switching device 54. There is. A hydraulic pressure supply passage 55 is connected to the input port Z of the hydraulic pressure switching device 54. Here, in the hydraulic pressure switching device 54, the downstream end of the switching oil passage 56, whose upstream end is always connected to the input port Z, is either the first output port Y ₁ , the stop port Y ₂ or the second output port Y ₃ . You can connect to the crab. Here, the hydraulic pressure switching device 54 is adapted to connect the downstream end of the switching oil passage 56 to any one of these ports in accordance with a control signal applied from the control unit C, and the downstream end is the first port. When connected to the output port Y ₁ , only the second lock member 42 is supplied with hydraulic pressure, and when connected to the second output port Y ₃ , the hydraulic pressure is the third.
Hydraulic pressure is supplied only to the lock member 43, and the stop port Y ₂
Is connected to the second and third locking members 42, 43.
Is not supplied with oil pressure.

In the hydraulic pressure switching device 54, the switching oil passage 5
Since the downstream end of 4 is connected to only one of the ports Y _{1 to} Y ₃ , there is no possibility that hydraulic pressure will be supplied to both the second lock member 42 and the third lock member 43. Therefore, the second lock member 42 and the third lock member 4
The state in which 3 and 3 are overlapped and locked, that is, a so-called double lock does not occur.

Incidentally, FIG. 4 shows another example of a hydraulic mechanism capable of preventing double lock. In FIG. 4, when the connecting pin 65 is fitted in the recess of the first locking member 66, the first locking member 66 is locked, and when the connecting pin 65 is fitted in the recess of the second locking member 67, the second locking member 66 is inserted. The lock member 67 is locked. The connecting pin 65 is connected to the piston 62 fitted in the cylinder 61. Here, when the hydraulic pressure is supplied from the first oil passage 64 side into the cylinder 61, the piston 62 and the connecting pin 65 move in the X ₁ direction to lock the first lock member 66. On the other hand, when hydraulic pressure is supplied from the second oil passage 63 into the cylinder 61,
The piston 62 and the connecting pin 65 move in the X ₂ direction to lock the second lock member 67. Even in such a configuration, the occurrence of double lock can be reliably prevented.

By the way, the control unit C is a comprehensive control device for the engine CE including the "intake valve control means" described in the claims, and various signals such as engine speed and throttle opening degree. Is used as control information to perform predetermined control of the engine CE. However, the engine CE by the control unit C
The general control of the present invention is well known, and the description thereof is omitted because such general control is not the subject of the present invention.
-Only the valve lift amount control which switches the valve lift amount of the 3rd intake valves 1-3 is explained.

(1) At a predetermined low speed or low load, hydraulic pressure is not supplied from the hydraulic control valve 51 to the first lock member 35, and the first intake valve 1 is driven by the second intake side cam 17. Thus, the valve lift amount of the first intake valve 1 is set to a small lift amount. On the other hand, in the hydraulic switching device 54,
The downstream end of the switching oil passage 56 is connected to the stop port Y ₂ , hydraulic pressure is not supplied to the second and third lock members 42 and 43, and the second and third intake valves 2 and 3 are always closed. To be done. In this case, air is supplied to the combustion chamber 7 only through the first intake port 4, but since the valve lift amount of the first intake valve 1 is set to a small lift amount, the opening portion of the first intake port 4 is opened. The passage cross section at is narrowed, and the flow velocity of the air flowing into the combustion chamber 7 is increased. Moreover, since the engine CE is of the intake three-valve type, the passage cross sections of the intake ports 4 to 6 are relatively narrow,
Therefore, the flow velocity of the air flowing into the combustion chamber 7 from the first intake port 4 is further increased. Also, the first intake port 4
Are arranged on the end side in a plan view as viewed in the arrangement direction of the intake ports 4 to 6 (first to third intake valves 1 to 3), so that the first intake port 4 is connected to the combustion chamber 7. The inflowing air is
It flows into the combustion chamber 7 in the cylinder circumferential direction. As described above, since the air having a high flow velocity flows into the combustion chamber 7 in the circumferential direction, a strong swirl is generated in the combustion chamber 7. Therefore, the air-fuel mixture is stratified around the spark plug 8,
The ignitability and combustibility of the air-fuel mixture are greatly improved.

(2) At a predetermined medium speed or medium load, the hydraulic pressure is not supplied from the hydraulic control valve 51 to the first lock member 35, and the first intake valve 1 is moved by the second intake side cam 17. When driven, the valve lift amount of the first intake valve 1 is set to a small lift amount. On the other hand, in the hydraulic switching device 54,
The downstream end of the switching oil passage 56 is connected to the first output port Y ₁ , and the hydraulic pressure is supplied only to the second lock member 42.
The third intake valves 2 and 3 are driven by the fourth intake-side cam 19, and the valve lift amounts of the second and third intake valves 2 and 3 are small lift amounts. In this case, air is supplied into the combustion chamber 7 from the first to third intake ports 4 to 6, that is, all the intake ports, but the valve lift amounts of the first to third intake valves 1 to 3 are all small lift amounts. Therefore, the flow velocity of the air flowing into the combustion chamber 7 from each of the intake ports 4 to 6 becomes high to some extent, and swirl is generated in the combustion chamber 7. Further, since air flows into the combustion chamber 7 from all the intake ports 4 to 6, sufficient filling efficiency is secured in the medium speed range even though the valve lift amount is small. Therefore, it is possible to secure sufficient engine output in the medium speed range while improving the ignitability and combustibility of the air-fuel mixture.

(3) At a predetermined high speed or high load, hydraulic pressure is supplied from the hydraulic control valve 51 to the first lock member 35, and the first intake valve 1 is driven by the first intake side cam 16. The valve lift amount of the first intake valve 1 is a large lift amount. On the other hand, in the hydraulic pressure switching device 54, the downstream end of the switching oil passage 56 is connected to the second output port Y ₃ , the hydraulic pressure is supplied only to the third lock member 43, and the second and third intake valves 2 and 3 are Driven by the third intake side cam 18, the valve lift amount of the second and third intake valves 2 and 3 is set to a large lift amount. In this case, air is supplied into the combustion chamber 7 from the first to third intake ports 4 to 6, that is, all intake ports, and the valve lift amounts of the first to third intake valves 1 to 3 are all large lift amounts. Therefore, it is possible to supply a large amount of air into the combustion chamber 7 by maximizing the advantage of the intake three-valve system. For this reason, the charging efficiency is significantly increased, and the engine output is significantly increased.

As described above, according to the present embodiment, in the intake three-valve engine, it is possible to perform a rational air supply suitable for each operating condition at any of low speed, medium speed and high speed. Various performances of the engine are greatly improved. Further, since it is only necessary to provide four intake side cams for each cylinder, the valve mechanism has a simple structure.

In this embodiment, the second intake valve 2 and the third intake valve 2
Although the valve lift amounts of the intake valves 3 are the same, of the second intake valve 2 and the third intake valve 3, a small lift of the second intake valve 2 located on the center side in the intake valve arrangement direction in plan view. Quantity,
It may be set to be larger than the small lift amount of the third intake valve 3 located on the end side. By doing so, the swirl generated in the combustion chamber 7 by the air flowing into the combustion chamber 7 from the first intake port 4 at the medium speed is changed by the air flowing into the combustion chamber 7 from the third intake port 6 by the air. It is prevented from being disturbed, swirl is further strengthened, and ignitability and combustibility are further enhanced.

[0042]

According to the first aspect of the invention, since the air is supplied to the combustion chamber from only one intake port at low speed, the flow velocity of the air flowing into the combustion chamber is increased and a strong swirl is generated. As a result, the air-fuel mixture is stratified, and the ignitability and combustibility of the air-fuel mixture are enhanced. Further, since air is supplied to the combustion chamber from the three intake ports at high speed, the charging efficiency is increased and the engine output is increased. Furthermore, if the first lift amount of each intake valve is set small and the second lift amount is set large, the swirl can be further strengthened at low speeds, and the ignitability / combustibility of the air-fuel mixture at medium speeds can be enhanced. It is possible to secure a sufficient engine output required at the middle speed while increasing it, and it is possible to significantly increase the filling efficiency at the high speed to increase the output of the engine.

According to the second invention, basically, the same operation and effect as those of the first invention can be obtained. Furthermore, since the first lift amount of each intake valve is a small lift amount and the second lift amount is a large lift amount, the swirl is significantly strengthened at low speeds, and the ignitability of the air-fuel mixture at medium speeds is increased. Combustibility is enhanced, and the required engine output at medium speed is sufficiently secured, and at high speed, the charging efficiency is significantly increased and the engine output is significantly increased.

According to the third invention, basically, the same action and effect as those of the first or second invention can be obtained. Further, since the first intake valve is arranged on the end side when viewed in the intake valve array direction in plan view, air flows in the cylinder circumferential direction from the first intake port into the combustion chamber, and swirl is generated. It will be further strengthened.

According to the fourth invention, basically, the same operation and effect as the third invention can be obtained. Furthermore, of the second intake valve and the third intake valve, the first lift amount of the intake valve located closer to the center in the intake valve arrangement direction in plan view is larger than the other lift amount. Therefore, the swirl generated by the air flowing into the combustion chamber from the first intake port is prevented from being disturbed by the air flowing into the combustion chamber from the third intake port, the swirl is strengthened, and the ignitability / combustibility is improved. Is further enhanced.

[Brief description of drawings]

FIG. 1 is an elevational cross-sectional explanatory view around a valve operating mechanism of an engine including a valve timing control device according to the present invention.

2 is a schematic plan view of an upper portion of a combustion chamber of the engine shown in FIG.

3 is a plan view of a valve mechanism on a cylinder head of the engine shown in FIG.

FIG. 4 is a schematic diagram of a hydraulic mechanism capable of preventing double lock of a lock member.

[Explanation of symbols]

 CE ... Engine C ... Control unit R ... Variable valve drive mechanism # 1 ... Cylinder 1-3 ... 1st-3rd intake valve 4-6 ... 1st-3rd intake port 7 ... Combustion chamber 15 ... Intake side camshaft 16 -19 ... First to fourth intake-side cams

Claims (4)

[Claims] 1. A valve timing control device for an intake three-valve engine in which first to third intake valves are provided in one cylinder, wherein the first intake valve is opened up to a first lift amount. A first intake valve driving means that can be driven by either one of a first lift characteristic for lifting and a second lift characteristic for lifting to a second lift amount at the valve opening timing; While the three intake valves are driven in synchronization with each other, both intake valves can be normally closed, and the first lift characteristic that lifts up to the respective first lift amount at the opening timing and the opening characteristic Second intake valve drive means that can be driven by any one of the second lift characteristics that lift up to the respective second lift amounts at the valve timing, and the second and third intake valves are normally closed at low speed. State, and at the medium speed, the first intake valve is And the second and third intake valves are driven with the first lift characteristic, and at a high speed, at least one of the first intake valve and the second and third intake valves has the second lift characteristic. In order not to be driven and the second and third intake valves are normally closed,
An valve timing control device for an engine, comprising: an intake valve control means for controlling first and second intake valve driving means. 2. The valve timing control device for an engine according to claim 1, wherein in the first intake valve, the first lift amount is a small lift amount and the second lift amount is a large lift amount. In the second and third intake valves, the valve timing control device for the engine is characterized in that the first lift amount is a small lift amount and the second lift amount is a large lift amount. 3. The valve timing control device for an engine according to claim 1 or 2, wherein the first intake valve is arranged on the end side when seen in the intake valve arrangement direction in plan view. Engine valve timing control device. 4. The valve timing control device for an engine according to claim 3, wherein, of the second intake valve and the third intake valve, the intake valve located closer to the center in the intake valve arrangement direction in plan view. Is larger than the first lift amount of the intake valve located on the end side, the valve timing control device for the engine.