JP3198762B2 - Variable valve train for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable valve operating apparatus for an internal combustion engine, and more particularly to a variable valve operating apparatus for an internal combustion engine which is provided with a valve stop mechanism for a tappet and performs a switching operation by hydraulic pressure.

[0002]

2. Description of the Related Art In an internal combustion engine, a camshaft is rotatably supported by a cylinder head, the camshaft is interlocked with a crankshaft by a transmission means such as a chain, and intake / exhaust is performed by a camshaft cam through a rocker arm. The valve is pushed down against the urging force of the valve spring to open and close the intake and exhaust valves that open to the combustion chamber. The opening / closing timing of the intake / exhaust valve is determined by the shape of the cam.

[0003] Further, there is a direct-acting type valve operating device for an internal combustion engine in which the upper portion of a tappet is brought into contact with a cam and a valve stem of a valve is connected to the tappet.

[0004] As a variable valve device for the internal combustion engine, there is one disclosed in Japanese Patent Publication No. 3-12208. The valve operating mechanism of an internal combustion engine disclosed in this publication applies a fluid pressure directly or indirectly to a spring means having a predetermined spring constant, so that a spring load of the spring means at a predetermined valve lift time is increased. In order to increase the spring load in the high-speed operation range, at least the spring load in the low-speed operation range,
The fluid pressure of the fluid pressurizing device acting on the spring means is increased in the high-speed operation range.

[0005] Another example is disclosed in Japanese Patent Application Laid-Open No. 5-52105. A variable valve timing lift device for an internal combustion engine disclosed in this publication is a variable valve timing lift device that switches between a low speed cam and a high speed cam of a camshaft by a variable mechanism, and is fitted to an upper portion of a lifter body that abuts an intake valve. A groove is provided, and a low-speed lifter that slides on the low-speed cam is provided, and a projection that fits into and disengages from the fitting groove is formed on the lower surface of the high-speed lifter that is vertically movable inside the low-speed lifter, A conversion means for rotating the lifter body in accordance with the engine operating state is provided, the valve lift / valve timing characteristics at the time of the engine low speed and the high speed are made variable, the switching response between the low speed side and the high speed side is improved, and the valve Prevents hammering and damage.

[0006]

In a conventional valve gear for an internal combustion engine, a rocker arm is formed by a first main body contacting a cam and a second main body connected to an intake / exhaust valve. There is a valve rest mechanism for a valve in which the first and second main bodies are connected by a detachable pin.

There is also a variable lift structure in which transmission of driving force from two cams is switched by using the same rocker arm.

However, in order to connect or separate the rocker arms divided into the first and second main bodies by inserting and removing the pins during high-speed operation of the engine, a large clearance is required between the pin insertion holes and the pins. This is necessary, and the valve lift timing during operation slightly deviates from the design value, which is disadvantageous in practical use.

In consideration of the durability of the rocker arm divided into the first and second body portions, the rocker arm must be increased in size, cannot be designed in a compact layout, and has a large weight. There is a problem,
Improvement was desired.

[0010]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention provides a method in which the upper portion of the tappet is brought into contact with a cam, and the valve stem of the valve is connected to the tappet via a rocker arm to swing the rocker arm. In a valve operating device for an internal combustion engine that opens and closes a valve, two cams having different lift functions for an intake valve or an exhaust valve are provided as a pair, and two tappets are arranged in contact with these cams. A rocker arm disposed between a tappet and a valve stem, a hydraulic passage connected to a piston of each tappet and controlling hydraulic pressure applied to the piston to control the amount of movement transmitted from the cam to the rocker arm. A suspension mechanism is configured.

A valve operating mechanism for an internal combustion engine in which an upper portion of a tappet is brought into contact with a cam and a valve stem of a valve is connected to the tappet via a rocker arm to swing the rocker arm to open and close the valve. A high-speed tappet and a low-speed tappet having a valve stop mechanism are provided as a pair for an intake valve or an exhaust valve, and these high-speed tappets and low-speed tappets are arranged in accordance with the number of cylinders. A first hydraulic passage communicating with the piston, a second hydraulic passage communicating with at least one of the low-speed tappet pistons, and a third hydraulic passage communicating with the remaining low-speed tappet pistons; First to third opening / closing valves are respectively provided in the middle of the third hydraulic passage, and the first to third opening / closing valves are opened / closed to operate the pin. By controlling the hydraulic pressure applied to the ton, characterized in that a control unit for controlling so as to any cylinder and combustion dormant controls the amount of movement transmitted to the rocker arm from the cam.

[0012]

According to the invention described above, when the tappet is operated, the piston is operated by hydraulic pressure to release the engagement state between the ball and the concave portion, and the coupling between the upper body and the lower body is released to bring into a rest state. At the same time, when the valve rest mechanism operates, the hydraulic pressure applied to the piston is controlled to control the amount of movement transmitted from the cam to the rocker arm.

During control by the control unit, the opening and closing operations of the first to third opening and closing valves are controlled to control the amount of movement transmitted from the cam to the rocker arm by controlling the hydraulic pressure applied to the piston. It is controlled so as to be in the combustion stop state.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIGS. 1 to 10 show a first embodiment of the present invention. In FIG. 1, 2 is a tappet.

The tappet 2 has an upper portion in contact with a cam (not shown) and a lower portion connected to a valve stem of a valve (not shown) through a rocker arm (not shown) to swing the rocker arm to open and close the valve. It is used for dynamic valve systems.

The tappet 2 includes an upper body 4, a lower body 6 that engages with the upper body 4,
A piston 8 that moves in the axial direction in the upper body 4 by hydraulic pressure, a ball 10 disposed around the outer periphery of the piston 8,
When the ball 10 is engaged, the upper body 4 and the lower body 6 are joined and integrated, and when the engagement state of the ball 10 is released by the operation of the piston 8, the upper body 4 and the lower body 6 And a recess 12 formed in the lower body 6 to release the connection and suspend the function, and constitutes a valve rest mechanism 14.

More specifically, the upper body 4 is configured as shown in FIG.
As shown in FIG. 1, a shim 16 which is formed in a closed cylindrical shape and is in contact with a cam (not shown) is provided at an upper portion, and a first shim 16 is provided inside.
A hydraulic passage 18 is formed.

An upper side cylindrical portion 20 protruding toward the lower body 6 is formed inside the upper body 4, and a holding portion 2 for movably holding the piston 8 in the cylindrical portion 20.
2 is attached.

A flange portion 24 is formed on the outer side of the lower body 6 which is formed as a bottomed cylindrical shape to prevent the lower body 6 from falling off when mounted, and a lower side cylindrical portion 26 projecting toward the upper body 4 is formed on the inner side. , Upper body 4 and lower body 6
Is engaged, the outer periphery of the connection portion is covered with a cover portion 28, and the outer periphery of the upper-side tubular portion 20 is attached to the lower-side tubular portion 26.
Are engaged.

The holding portion 22 for movably holding the piston 8 has first and second space portions 30 and 32 formed by a flange portion 8f formed on the piston 8 and an inner peripheral surface of the holding portion 22.
And a first spring 34 is provided in the first space 30. The first spring 34 is provided to reduce the second space 32 by the urging force, that is, to make the piston 8 protrude toward the lower body 6 side. Have been.

A second hydraulic passage 36 communicating with the first hydraulic passage 18 is provided between the upper cylindrical portion 20 and the holding portion 22.
And the end of the second hydraulic passage 36 is connected to the second space 3.
2 to make the second space 32 function as a hydraulic chamber.

The upper cylindrical portion 20 and the lower cylindrical portion 2
Due to the engagement with 6, a third space portion 38 is formed outside and a fourth space portion 40 is formed inside.

In the third space 38, there is provided a second urging member for urging the upper body 4 and the lower body 6 in a direction in which they are separated from each other.
A spring 42 is provided, and in the fourth space 40,
The tip 8a of the piston 8 is made to protrude, and a ball 10 is disposed around the outer periphery of the piston 8.
Is prevented by the fall prevention member 44.

The concave portion 12 with which the ball 10 engages
It is formed in the lower body 6, that is, on the inner peripheral surface of the lower cylindrical portion 26.

The tip 8a of the piston 8 has a tip 8a
From the side, a small diameter portion 8-1, a slope portion 8-2, and a large diameter portion 8-3 are sequentially formed.

The first and second hydraulic passages 1 independent of the piston 8 of the tappet 2
8 and 36, and controls the hydraulic pressure applied to the piston 8 to control the amount of movement transmitted from the cam to the rocker arm.

The valve train of the internal combustion engine having the valve stop mechanism 14 will be described with reference to FIGS. 5 to 10. If the tappet 2 is hydraulically switched, two types of valve lifts corresponding to the lift function of the cam will be described. The valve operating mechanism 52 is configured to bring the valve into a state and also to bring the valve into a rest state.

That is, as shown in FIG.
An intake port 60 and an exhaust port 62 communicating with the combustion chamber 58 of the cylinder head 56 are provided, and two intake valves 64-open and close the downstream end of the intake port 60.
1, 64-2 and two exhaust valves 66-1, 66-2 for opening and closing the upstream end of the exhaust port 62.
Is provided.

As shown in FIG. 5, two tappets 72 are connected to the valve stems 68-1 and 68-2 of the intake valves 64-1 and 64-2 through one Y-shaped intake side rocker arm 70. -1, 72-2 are provided, and the tappet 72-
Cams 74-1 and 74-2 are in contact with the upper portions of 1 and 72-2.

The valve stems 76-1 and 76-2 of the exhaust valves 66-1 and 66-2 have a Y-shaped exhaust side rocker arm 7 as shown in FIGS.
8, two tappets 80-1 and 80-2 are disposed, and a cam 82-
1, 82-2 are in contact.

Reference numeral 84a denotes an adjuster screw for adjusting the distance between the intake side rocker arm 70 and the intake valves 64-1 and 64-2, 84b denotes a nut, and 86 denotes an exhaust side rocker arm 78.
A lash adjuster 88 for adjusting the distance between the valve and the exhaust valves 66-1 and 66-2 is a shim for adjusting the distance.

Then, for example, a valve operating mechanism 52 for causing a stop state of the valve is provided on the exhaust side. This valve train 5
As shown in FIGS. 8 to 10, two cams 82-2 having different lift functions, that is, two cams 82-2 for high speed and low speed.
1, 82-2 are provided as a pair, and these cams 82-2 are provided.
1, 82-2 to be in contact with the valve deactivating mechanism 90-1, 9
Tappets 80-1 and 80-2 having 0-2, respectively, and two tappets 80-1, 80-2 and 2
Valve stem 76 of the individual exhaust valves 66-1 and 66-2.
A single Y-shaped exhaust side rocker arm 78 is disposed between the tappets 80-1 and 76-2, and the tappets 80-1 and 80-2 are switched by hydraulic pressure for the lift function of the cams 82-1 and 82-2. According to the configuration, two types of valve lift states are provided, and the exhaust valves 66-1 and 66-2 are also brought into a rest state.

In the cylinder head 56, hydraulic passages 92-1 and 92-2 are formed, respectively, and two tappets 80-1, 8-2 are formed from the hydraulic passages 92-1 and 92-2.
Oil is supplied to 0-2.

Next, the operation will be described.

First, the operation of the valve rest mechanism 14 will be described. When no hydraulic pressure is supplied to the second space 32, as shown in FIG.
The piston 8 is projected into the fourth space 40 of the lower body 6 by the biasing force of 4, and the ball 10 is pushed outward by the large-diameter portion 8-3 of the piston 8, so that the ball 10 is engaged with the concave portion 12, and The body 4 and the lower body 6 are locked and integrated.

At this time, when the driving force from the cam (not shown) is transmitted to the shim 16 of the upper body 4, the integrated tappet 2 transmits the driving force to the valve stem of the valve (not shown) to open and close the valve. ing.

When hydraulic pressure from a hydraulic pressure source (not shown) is supplied to the second space 32 through the first and second hydraulic passages 18 and 36, the first spring 34 as shown in FIGS. The hydraulic pressure expands the second space 32 against the biasing force of
0 is located at the outer peripheral portion of the small diameter portion 8-1 of the piston 8, and the locked state between the upper body 4 and the lower body 6 is released,
It becomes free state.

Therefore, when the driving force from the cam (not shown) is transmitted to the shim 16 of the upper body 4, the tappet 2 is opposed to the urging force of the second spring 42 as shown in FIG.
The upper body 4 and the lower body 6 are deeply engaged with each other, the tappet 2 is compressed from the vertical direction to shorten the overall length, and the driving force is not transmitted to the valve stem (not shown), so that the valve cannot be opened and closed. It is.

When the cam is not in contact with the cam, the engagement between the upper body 4 and the lower body 6 becomes normal by the urging force of the second spring 42 disposed in the third space 38, and The full length of the tappet 2 returns.

In this free state, the tappet 2
The contracting operation shown in FIG. 3 and the extending operation shown in FIG. 4 are repeated according to the movement of the cam.

At this time, if the supply of the hydraulic pressure is stopped, the tappet 2 can be locked, and if the supply of the hydraulic pressure is continued, the tappet 2 is unlocked,
That is, the free state is continued.

As a result, the free state can be reliably established by the tappet 2 which is switched by hydraulic pressure.
Compared to the conventional one, there is no possibility that the valve lift timing during operation is shifted, which is practically advantageous.

Further, by switching the tappet 2 by hydraulic pressure, it is not necessary to consider the durability of the rocker arm, the rocker arm does not increase in size, the layout can be made compact, and the weight can be reduced. There are no major problems.

The operation of the valve mechanism 52 will now be described. In the high-speed lift state, as shown in FIG. 8, oil is supplied to the tappet 80-2 via the hydraulic passage 92-2, 80-1 is locked, and the tappet 80-2 is in the unlocked free state, and the driving force from the high speed cam 82-1 is transmitted to the exhaust side rocker arm 78 via the tappet 80-1. The exhaust valve 6 is controlled by the exhaust side rocker arm 78.
6-1 and 66-2 are opened and closed.

At this time, the tappet 80-2 is in a free state, and the driving force from the low speed cam 82-2 is not transmitted.

When the vehicle is in the low-speed lift state, FIG.
As shown in the figure, the tappet 80-
1 is supplied with oil, the tappet 80-2 is locked, and the tappet 80-1 is free.
The driving force from the low speed cam 82-2 is transmitted to the exhaust side rocker arm 78 via the tappet 80-2, and the exhaust side rocker arm 78 causes the exhaust valves 66-1, 66-.
2 is opened and closed. At this time, tappet 80-1
Is in a free state, and the driving force from the high-speed cam 82-1 is not transmitted.

Further, when the valve is in the stop state, the operation shown in FIG.
As shown in FIG. 5, oil is supplied to the tappets 80-1 and 80-2 via the hydraulic passages 92-1 and 92-2, respectively, so that the tappets 80-1 and 80-2 are in the free state, respectively. -1 and the driving force from the low-speed cam 82-2 are absorbed by the expansion and contraction operations of the tappets 80-1 and 80-2 and are not transmitted to the exhaust side rocker arm 78, and the exhaust valves 66-1 and 66-2 are It does not open and close. If this switching operation is applied only to a specific cylinder, a variable cylinder engine can be provided.

The tappets 80-1 and 80-2, which are switched by hydraulic pressure, can reliably switch between a high-speed lift state, a low-speed lift state, and a free state. There is no fear that the valve lift timing will shift, which is practically advantageous.

Further, by switching the tappets 80-1 and 80-2 by hydraulic pressure, there is no need to consider the durability of the rocker arm, so that the rocker arm does not become large and has a compact layout. And there is no problem that the weight becomes large.

FIGS. 11 and 12 show a second embodiment of the present invention. In the second embodiment, the first
Parts that perform the same functions as in the embodiment will be described with the same reference numerals.

The feature of the second embodiment is that the first to third opening / closing valves 112, 114 and 116 are opened and closed to control the hydraulic pressure applied to the pistons to control the amount of movement transmitted from the cam to the rocker arm. In addition, a control unit 100 for controlling an arbitrary cylinder to be in a combustion stop state, that is, a variable cylinder is provided.

That is, the high-speed tappet 102 having the valve stop mechanism and the low-speed tappet 104 having the valve stop mechanism described in the first embodiment are provided as a pair for an intake valve or an exhaust valve.
02 and the low-speed tappet 104 are arranged in accordance with the number of cylinders, for example, four cylinders, and a first hydraulic passage 106 is provided to communicate with the piston of the high-speed tappet 102. At least one of the pistons of the low-speed tappet 104 is provided. , For example, second,
A second hydraulic passage 108 communicating with the fourth low-speed tappets 104-2 and 104-4 is provided, and the remaining first and third low-speed tappets 104-1 and 104-1 as low-speed tappets are provided.
A third hydraulic passage 110 communicating with the piston 4-3 is provided, and first to third opening / closing valves 112, 114, 116 are provided in the middle of the first to third hydraulic passages 106, 108, 110, respectively. Third open / close valve 112, 114, 11
6 is controlled by the control unit 100.

Then, the first to third opening / closing valves 112, 114, 116 are opened and closed by the control section 100,
By controlling the amount of movement transmitted from the cam to the rocker arm by controlling the hydraulic pressure applied to the piston, as shown in FIG. 12, it is possible to control switching between a high-speed mode, a low-speed mode, and a two- or four-cylinder deactivation mode. It is.

That is, by closing the first opening / closing valve (V1) 112 and opening the second opening / closing valve (V2) 114 and the third opening / closing valve (V3) 116, the high-speed mode can be achieved. When the opening and closing valve 112 is opened and the second and third opening and closing valves 114 and 116 are closed, a low-speed mode is set, and the first and second opening and closing valves 11 and 11 are opened.
2 and 114 are opened, and the third opening / closing valve 116 is opened.
Is closed, a two- or four-cylinder deactivation mode can be set.

When the engine is started, since the first to third opening / closing valves 112, 114, 116 are closed, oil is not supplied to the tappets 102, 104, and both tappets 102, 104 are locked. The tappet is about to be locked, and the tappets are sequentially locked according to the rotation of the cam at the time of starting.

The first to third opening / closing valves 112, 1
Predetermined on-off valves in 14, 116 are opened, and
For a few seconds during startup until oil is supplied to the tappet by a predetermined hydraulic passage in the third hydraulic passages 106, 108, 110, the opening / closing valve is opened / closed by a cam with a large lift.

Then, the control unit 100 controls the first
By opening and closing the third opening / closing valves 112, 114, and 116 to control the amount of movement transmitted from the cam to the rocker arm by controlling the hydraulic pressure applied to the piston, the high-speed mode and the low-speed mode are controlled by the hydraulic pressure. It is possible to smoothly control the switching to the stop mode, and there is no possibility that the valve lift timing during operation is shifted as compared with the conventional one, which is practically advantageous.

The first to third opening / closing valves 112,
By controlling the opening and closing operations of the 114 and 116 by the control unit 100, there is no need to consider the durability of the rocker arm, the rocker arm does not increase in size, the layout can be made compact, and the weight can be reduced. There are no major problems.

[0060]

As described above in detail, according to the present invention, an internal combustion engine in which the upper portion of the tappet is brought into contact with the cam, the valve stem of the valve is connected to the tappet via the rocker arm, and the rocker arm is swung to open and close the valve. In a valve train of an engine, two cams having different lift functions for an intake valve or an exhaust valve are provided as a pair, and a tappet is arranged in contact with these cams.
One rocker arm is arranged between each tappet and the valve stem, and an independent hydraulic passage is connected to the piston of each tappet to control the hydraulic pressure applied to the piston to control the amount of movement transmitted from the cam to the rocker arm. Because the mechanism is configured, the amount of movement transmitted from the cam to the rocker arm can be controlled by a valve pause mechanism that controls hydraulic pressure applied to the piston, and a high-speed lift state, a low-speed lift state, and a free state by a tappet that switches by hydraulic pressure The valve lift timing during operation is not at all likely to be deviated as compared with the conventional one, which is practically advantageous.

Further, a valve operating mechanism for an internal combustion engine that opens and closes a valve by bringing the upper portion of the tappet into contact with a cam and connecting the valve stem of the valve to the tappet via a rocker arm to swing the rocker arm is provided. A high-speed tappet and a low-speed tappet having a valve stop mechanism are provided as a pair for an intake valve or an exhaust valve, and these high-speed tappets and low-speed tappets are arranged in accordance with the number of cylinders. A first hydraulic passage communicating with the piston, a second hydraulic passage communicating with at least one of the low-speed tappet pistons, and a third hydraulic passage communicating with the remaining low-speed tappet pistons; First to third on-off valves are respectively provided in the middle of the third hydraulic passage, and the first to third on-off valves are opened and closed to fix A control unit is provided to control the amount of movement transmitted from the cam to the rocker arm by controlling the hydraulic pressure applied to the cylinder, and to control the arbitrary cylinder to be in a combustion stop state. It can control the amount of movement transmitted from the cam to the rocker arm by operating and controlling the hydraulic pressure applied to the piston, and can smoothly switch between high-speed mode, low-speed mode, and two- or four-cylinder deactivated mode by hydraulic pressure. There is no fear that the valve lift timing during operation is shifted compared to
It is practically advantageous.

[Brief description of the drawings]

FIG. 1 is a sectional view of a tappet showing a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a cross-sectional view showing a contracted state of the tappet in a free state.

FIG. 4 is a cross-sectional view showing an extended state of the tappet in a free state.

FIG. 5 is a schematic diagram of an engine.

FIG. 6 is a schematic plan view of an intake rocker arm.

FIG. 7 is a schematic view from the direction of a white arrow in FIG. 5;

FIG. 8 is a schematic diagram showing a high-speed lift state.

FIG. 9 is a schematic view showing a low-speed lift state.

FIG. 10 is a schematic diagram showing a free state.

FIG. 11 is a schematic configuration diagram for controlling a variable cylinder according to a second embodiment of the present invention.

FIG. 12 is a diagram showing a relationship between an opening / closing valve and each mode.

[Explanation of symbols]

 2 Tappet 4 Upper body 6 Lower body 8 Piston 8a Tip 8f Flange part 8-1 Small diameter part 8-2 Slope part 8-3 Large diameter part 10 Ball 12 Concave part 14 Valve stop mechanism 16 Shim 18 First hydraulic passage 20 Upper cylindrical part Part 22 Holding part 24 Flange part 26 Lower side cylindrical part 28 Cover part 30 First space part 32 Second space part 34 First spring 36 Second hydraulic passage 38 Third space part 40 Fourth space part 42 Second spring 44 Fall prevention member 52 Valve train

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01L 13/00 302 F01L 13/00 301 F01L 1/24

Claims (2)

(57) [Claims] 1. A valve operating system for an internal combustion engine for opening and closing the valve to oscillate the rocker arm to contact the valve stem of the valve through the rocker arm to the tappet with contacting the tappet top to the cam, an intake valve or an exhaust
It provided two cams of different lift function for the gas valve as a pair, in contact with these cams disposed one rocker arm between two tappet and the valve stem with respectively disposed tappet, each Independent oil for tappet piston
By connecting the pressure passage and controlling the hydraulic pressure applied to the piston,
A bar that controls the amount of movement transmitted from the cam to the rocker arm.
A variable valve train for an internal combustion engine, comprising a lubrication stop mechanism. 2. A valve operating system for an internal combustion engine for opening and closing the valve to oscillate the rocker arm to contact the valve stem of the valve through the rocker arm to the tappet with contacting the tappet top to the cam, having a valve resting mechanism A high-speed tappet and a low-speed tappet having a valve stop mechanism are provided as a pair for an intake valve or an exhaust valve, and the high-speed tappet and the low-speed tappet are arranged in accordance with the number of cylinders. A first hydraulic passage communicating with the piston of the high-speed tappet , a second hydraulic passage communicating with at least one of the low-speed tappet pistons, and a second hydraulic passage communicating with the remaining low-speed tappet pistons . 3 hydraulic passage is provided, the first to third on-off valve provided respectively in the middle first to third hydraulic passage, said by opening and closing these first to third on-off valve Wherein by controlling the hydraulic pressure applied to the piston cam
A variable valve train for an internal combustion engine, comprising: a control unit that controls the amount of movement transmitted from the engine to the rocker arm and controls an arbitrary cylinder to be in a combustion stop state.