JPH0783013A - Variable valve system of internal combustion engine - Google Patents

Abstract

PURPOSE:To change the opening/closing time of a valve and draw out the performance of an engine effectively by making oil pressure to a valve side piston openable by connecting to the window of a sleeve an oil hole provided at a cam side piston, inclining the window edges of the sleeve in a turning direction, and changing the intercepting position of a relief hole provided at the piston by means of inclination. CONSTITUTION:The lift of a cam 22 is transmitted to a cam side piston 27 by means of a rocker arm 25. A sleeve 30 provided with a window 35 is turned by means of a pinion 37 by driving a rack bar 38, and the position of the window 35 is changed. In the left direction of the drawing from an axial window edge 50, an upper part window edge 51 is formed into downward inclination and a lower part window edge 52 is formed into upward inclination. As for the oil hole 33 and the relief hole 34 of the cam side piston 27, at the initial position, the relief hole 34 communicates with the window 35, and the oil hole 33 is made to be at a position to be intercepted, and at a descending position, the oil hole 33 communicates with the window 35, and the relief hole 34 is made to be intercepted. Meanwhile, the interception positions of the relief hole 34 and the oil hole 33 are changed by the turning movement of the sleeve 30. Thus, performance improvements at the times of engine idling and high rotation can be compatible with each other.

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 system for an internal combustion engine which controls the valve lift of an intake valve or an exhaust valve via hydraulic pressure.

[0002]

2. Description of the Related Art As a variable valve operating device of this type, as disclosed in, for example, Japanese Patent Application Laid-Open No. 1-134013,
An intake valve that includes a cam that is driven to rotate synchronously with the engine, a cam-side piston that reciprocates following the cam, and a valve-side piston that interlocks with the cam-side piston via hydraulic pressure Alternatively, there is one that opens and closes an exhaust valve.

This is because the valve is closed by opening the hydraulic pressure release valve during the opening and closing operation of the valve to release the hydraulic pressure acting on the valve side piston from the cam side piston, and the opening timing of the hydraulic pressure release valve is controlled. Thus, the valve lift amount is adjusted.

One of the hydraulic release valves uses a rotary sleeve valve as shown in FIG. The operation of the cam 1 is transmitted to the cam side piston 3 via the rocker arm 2, and the window 5 is provided in the rotary sleeve 4 covering the outside of the cam side piston 3.

During the reciprocating motion of the cam side piston 3, the oil hole 6 provided in the cam side piston 3 communicates with the window of the rotary sleeve 4, whereby the hydraulic pressure to the valve side piston (not shown) is released, and the valve is opened. Is closed by the valve spring. The window 5 of the rotary sleeve 4 is formed in a triangular shape, and by rotating the rotary sleeve 4 by driving the rack bar 7, the oil hole 6 of the cam side piston 3 and the window 5 of the rotary sleeve 4 communicate with each other. The timing is changed and the valve lift amount is adjusted.

The rocker arm 2 and the cam side piston 3
A rotation stopping mechanism 8 for the cam-side piston 3 is provided between and.

[0007]

However, in the conventional variable valve actuating device having such a rotary sleeve valve, even if the valve lift amount and the valve closing timing are changed, as shown in FIG. You cannot change the timing of opening the valve.

For this reason, for example, when it is used for an intake valve, if the valve opening timing is set so as to obtain the required opening characteristic at high engine speed, the valve opening timing will be early and the valve overlap will become large during idling. , Idle stability becomes difficult to obtain. Therefore, it is difficult to achieve both the stability at the time of idling and the securing of the output at the time of high rotation, and there is a problem that the performance of the internal combustion engine cannot be effectively brought out.

Although there is a system in which the valve opening timing is changed by changing the cam driving timing, it is inevitable that the device becomes complicated.

The present invention aims to solve such problems.

[0011]

SUMMARY OF THE INVENTION The present invention is directed to a cam which is rotationally driven in synchronization with an engine, a cam side piston which reciprocates following the cam, and a valve side which is interlocked with the cam side piston via hydraulic pressure. Equipped with a piston and an intake valve or an exhaust valve that opens and closes following the piston on the valve side,
A window is provided in a freely rotatable sleeve that covers the cam side piston,
In the variable valve operating device of the internal combustion engine, which is capable of releasing the oil pressure to the valve-side piston during the lift by connecting the oil hole provided in the cam-side piston with the window of the sleeve along with the lift of the cam, An escape hole that can communicate with the window of the sleeve is provided within the small lift area of the cam, and the window edge of the sleeve is formed so as to be inclined in the rotating direction so that the blocking position of this escape hole can be changed by the rotating position of the sleeve. To do.

Further, the relief hole is shaped so as to gradually reduce the communication area with the window of the sleeve when the cam side piston is shut off in accordance with the operation of the cam side piston.

[0013]

[Operation] The cam side piston starts operating due to the lift of the cam. At this time, while the clearance hole of the cam side piston communicates with the window of the sleeve, the hydraulic pressure between the cam side piston and the valve side piston is released. Therefore, the valve does not move, and when the clearance hole is blocked by the window edge of the sleeve in accordance with the operation of the cam side piston, the hydraulic pressure acts on the valve side piston from the cam side piston and the valve starts to open.

Since the window edge of the sleeve is inclined, by turning the sleeve, the blocking position of the escape hole can be changed and the valve opening timing can be changed.

Further, if the relief hole is formed so as to be blocked while gradually reducing the area of communication with the sleeve, a smooth rise of the valve lift can be obtained.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIGS. 1 to 4, 20 is a cylinder head of an engine, 21 is an intake valve or an exhaust valve, 2
Reference numeral 2 is a cam that is driven to rotate in synchronization with the engine, and 23 is a housing provided on the cylinder head 20.

The cam 22 is in contact with a roller follower 26 of a rocker arm 25 whose base end is supported by a pivot end 24, and the tip end of the rocker arm 25 is a cam side piston 27.
Abutted against.

The lift of the cam 22 is transmitted to the cam side piston 27 via the rocker arm 25, and the cam side consisting of the groove 28 and the projection 29 engaging with the groove 28 is provided between the rocker arm 25 and the cam side piston 27. A rotation stopping mechanism for the piston 27 is provided.

The cam-side piston 27 is slidably fitted in a sleeve 30 housed in the housing 23, and the hydraulic chamber 31 side of the housing 23 is formed into a cylindrical portion.
A cam spring 32 for urging the cam side piston 27 toward the rocker arm 25 is provided in the inside of 1.

An oil hole 33 and a relief hole 34 are provided at predetermined positions on the cylindrical portion of the cam side piston 27.

The sleeve 30 is rotatably housed in the housing 23, and a window 35 is opened at a predetermined position on the circumferential surface. A lid 36 is attached to the housing 23 so that the sleeve 30 does not move in the axial direction.

A pinion 3 is provided at the end of the circumferential surface of the sleeve 30.
7 is formed, and the rack bar 38 inserted into the housing 23 is engaged with the pinion 37. The rack bar 38 is connected to an actuator (not shown). When the rack bar 38 is driven by the actuator, the sleeve 30 is rotated and the position of the window 35 is changed.

A predetermined hydraulic oil is supplied from a hydraulic pump (not shown) to the oil passage 39 opened in the window 35 of the sleeve 30 via a check valve 40. An accumulator 41 is provided in the oil passage 39, and is connected to the hydraulic chamber 31 via a check valve 42.

A second hydraulic chamber 45, which is connected via an oil passage 43, is formed immediately below the hydraulic chamber 31, and a valve-side piston that abuts the end of the stem 46 of the valve 21 in the second hydraulic chamber 45. 47 is slidably accommodated.

On the opening side of the second hydraulic chamber 45 of the oil guide path 43, a step portion 54 is formed in which the tip end portion of the valve side piston 47 enters and is seated.

A guide hole 44 for guiding the hydraulic oil from the oil guide passage 43 to the second hydraulic chamber 45 is formed at the tip of the valve side piston 47, and a check valve 48 is provided in the middle of the guide hole 44.

The guide hole 44 communicates with the second hydraulic chamber 45 in front of the check valve 48 via the orifice passage 55.

The valve 21 is biased in the valve closing direction by a valve spring 49.

Here, the window 35 of the sleeve 30 is formed in a triangular shape as shown in FIGS. 3 and 4, and the window edge 5 in the axial direction is formed.
From 0 to the left in the figure, the upper window edge 51 is formed with a predetermined downward inclination, and the lower window edge 52 is formed with a predetermined upward inclination.

Oil hole 33 and escape hole 3 of cam side piston 27
4 is a position where the escape hole 34 communicates with the window 35 of the sleeve 30 when the cam side piston 27 is in the initial position as shown in FIGS. 3 and 4 (position close to the window edge 52 of the lower portion of the sleeve 30). In addition, the oil hole 33 is provided at a position to be blocked.

As the cam side piston 27 descends from the illustrated position, the escape hole 34 is blocked by the window edge 52 at the lower portion of the sleeve 30, and when the cam side piston 27 further descends, the oil hole 33 is formed in the sleeve 30. While exposed from the upper window edge 51 and communicated with the window 35, the cutoff position of the escape hole 34 (within the small lift area of the cam 22) and the communication position of the oil hole 33 are changed by the rotational position of the sleeve 30. It is like this.

Further, the escape hole 34 is formed in a shape in which the opening area is gradually reduced in the direction opposite to the window edge 52 at the bottom of the sleeve 30, and the window 35 is formed as the cam side piston 27 descends.
The area of communication with and is gradually reduced while being blocked.

With such a structure, when the cam side piston 27 is in the initial position in the non-lifting area of the cam 22, the hydraulic chamber 31 moves from the escape hole 34 of the cam side piston 27 to the oil through the window 35 of the sleeve 30. It communicates with the passage 39.

From this state, when the cam side piston 27 is pushed down as the cam 22 is lifted, the hydraulic pressure generated in the hydraulic chamber 31 is maintained in the accumulator of the oil passage 39 while the clearance hole 34 communicates with the window 35 of the sleeve 30. When the relief hole 34 is stored in 41, and the escape hole 34 is blocked by the window edge 52 at the lower portion of the sleeve 30, the hydraulic pressure in the hydraulic chamber 31 rises, and the hydraulic pressure is applied to the oil guide passage 43 and the check valve 4 of the valve side piston 47.
By opening 8 and flowing into the second hydraulic chamber 45 from the guide hole 44, the valve side piston 47 is pushed down and the valve 21 starts to open.

The blocking position of the escape hole 34 is changed by the rotating position of the sleeve 30, and the sleeve 30 is rotated rightward in FIGS. 3 and 4 via a rack bar 38 connected to an actuator (not shown). Then, the escape hole 34 is blocked early, and the valve opening timing of the valve 21 is advanced. When the sleeve 30 is rotated leftward in FIGS. 3 and 4, the escape hole 34 is blocked late. As a result, the opening of the valve 21 is delayed.

At this time, when the valve-side piston 47 makes a small stroke and the tip end thereof deviates from the step portion 54 of the oil guide passage 43, the oil pressure is directly introduced from the oil guide passage 43 into the second hydraulic chamber 45, and the valve 21 is opened.

When the cam side piston 27 is further pushed down, the oil hole 33 of the cam side piston 27 is communicated with the window 35 of the sleeve 30 and acts on the hydraulic pressure of the hydraulic chamber 31 and the valve side piston 47. The hydraulic pressure in the hydraulic chamber 45 is released, and the valve 21 is closed by the spring 49.

The communicating position of the oil hole 33 is changed to the relief hole 34 by the turning position of the sleeve 30 as well.
When 0 is rotated to the right in FIGS. 3 and 4, the oil hole 33 is communicated at a later time, the valve closing timing of the valve 21 is delayed, and the sleeve 30 moves to the left in FIGS. 3 and 4. When rotated, the oil hole 33 is communicated at an early stage, and the valve 21 is closed earlier.

At this time, the hydraulic oil in the second hydraulic chamber 45 is first returned from the oil guide passage 43, and immediately before the valve 21 is closed, the tip of the valve side piston 47 enters the step 54 of the oil guide passage 43. As a result, it is returned from the orifice passage 55. Therefore, the speed of the valve 21 is moderated immediately before it is closed, and the valve 21 is smoothly closed.

When the cam side piston 27 is returned and the oil hole 33 is shut off, the hydraulic pressure in the accumulator 41 is returned to the hydraulic chamber 31 via the check valve 42, and the opening / closing operation is completed.

Since the valve 21 is opened and closed in this way, the valve opening timing of the valve 21 can be advanced or delayed as shown in FIG. Therefore, when the valve opening timing is late, the valve lift is small, and when the valve opening timing is early, the valve lift is large.

Therefore, when applied to the intake valve, by delaying the valve opening timing when the engine is idle to reduce the valve overlap, good idle stability can be ensured, and when the engine is running at high engine speed. By increasing the valve opening timing and increasing the charging efficiency, higher output can be achieved and engine performance is improved.

Further, since the relief hole 22 which is closed by the lowering of the cam side piston 27 is shaped so as to be closed while gradually decreasing the area of communication of the sleeve 30 with the window 35, the hydraulic pressure rises sharply when the valve 21 is opened. Therefore, it is possible to obtain a smooth opening operation of the valve 21 without moving up.
Generation of sound, vibration, etc. can be suppressed.

[0045]

As described above, according to the present invention, the cam that is rotationally driven in synchronization with the engine, the cam side piston that reciprocates following the cam, and the valve side that interlocks with the cam side piston via hydraulic pressure are provided. The oil provided on the cam side piston is provided with a piston and an intake valve or an exhaust valve that opens and closes following the valve side piston. In the variable valve operating system of the internal combustion engine, which allows the hydraulic pressure to be released to the valve side piston during lifting by allowing the hole to communicate with the window of the sleeve, the cam side piston is connected to the sleeve window within the small lift range of the cam. Since a relief hole that can communicate is provided and the window edge of the sleeve is formed to be inclined in the rotation direction so that the blocking position of this relief hole is changed by the rotation position of the sleeve, the valve opening timing Can be changed by the rotation of the sleeve, during idling of the engine, it is possible to achieve both improved performance at high rotation.

The valve can be smoothly opened by forming the relief hole so as to block the communication area with the window of the sleeve while gradually decreasing the area.

[Brief description of drawings]

FIG. 1 is a sectional view of an example.

FIG. 2 is a partial cross-sectional view.

FIG. 3 is a partial perspective view.

FIG. 4 is a front view of a window of the sleeve, an escape hole, and an oil hole.

FIG. 5 is an open characteristic diagram of a valve.

FIG. 6 is a partial perspective view of a conventional example.

FIG. 7 is an open characteristic diagram of a conventional example.

[Explanation of symbols]

 21 valve 22 cam 25 rocker arm 27 cam side piston 30 sleeve 31 hydraulic chamber 32 cam spring 33 oil hole 34 escape hole 35 window 38 rack bar 39 oil passage 40 check valve 41 accumulator 42 check valve 43 oil conduit 44 guide hole 45 Second hydraulic chamber 47 Valve side piston 48 Check valve 49 Valve spring 51 Window edge 52 Window edge 54 Step portion 55 Orifice passage

Claims (2)

[Claims] 1. A cam which is rotationally driven in synchronization with an engine,
A cam side piston that reciprocates following the cam, and a valve side piston that interlocks with the cam side piston via hydraulic pressure,
Equipped with an intake valve or an exhaust valve that opens and closes following the valve side piston, a window is provided in a freely rotatable sleeve that covers the cam side piston, and the oil hole provided in the cam side piston as the cam lifts By connecting to the window of
In a variable valve operating system for an internal combustion engine capable of releasing hydraulic pressure to a valve side piston during a lift, the cam side piston is provided with an escape hole that can communicate with a window of a sleeve within a small lift area of the cam, and this escape A variable valve operating device for an internal combustion engine, wherein a window edge of the sleeve is formed to be inclined in a rotation direction so that a blocking position of the hole is changed depending on a rotation position of the sleeve. 2. The variable motion of the internal combustion engine according to claim 1, wherein the relief hole has a shape in which a communication area with the window of the sleeve is gradually reduced when the cam side is shut off in accordance with the operation of the cam side piston. Valve device.