JPH042765B2 - - Google Patents

Description

Detailed Description of the Invention A. Object of the Invention (1) Industrial Field of Application The present invention relates to a cylindrical rotating shaft connected to a camshaft; a timing wheel that is arranged coaxially with the rotating shaft and driven from the crankshaft to enable relative rotation of the rotating shaft; A piston biased by a spring toward one side in the axial direction; a phase adjustment mechanism that interlocks and connects the piston, timing wheel, and rotating shaft to change the rotational phase of the timing wheel and rotating shaft in accordance with the axial movement of the piston; The present invention relates to a valve train for an internal combustion engine, comprising: and;

(2) Conventional technology Conventionally, such a device is disclosed in, for example, Japanese Patent Application Laid-Open No.
It is known from the publication No. 268810.

(3) Problems to be Solved by the Invention This device changes the operating timing of the intake valve or exhaust valve of the engine by changing the phase between the timing wheel and the camshaft using a phase adjustment mechanism. In the conventional system described above, the piston moves between two positions: when hydraulic pressure is supplied to the hydraulic chamber and when hydraulic pressure is released, and the opening/closing timing of the intake valve or exhaust valve is advanced by a certain value. The only control available is whether to slow down the speed by a certain value or to slow it down by a certain value.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a valve operating system for an internal combustion engine that allows stepless control of opening/closing timing.

B. Structure of the Invention (1) Means for Solving Problems According to the present invention, a hydraulic chamber facing one axial end of the piston, a hydraulic pressure supply path, and a hydraulic release path are interlocked and connected to the piston. A servo valve is interposed, which includes a sleeve that is slidably fitted into the rotating shaft and a spool that is movable relative to the shaft and slidably fitted to the sleeve. The spool is configured to switch the communication state between the hydraulic chamber and the hydraulic pressure supply path or the hydraulic pressure release path by the axial movement of the spool to the disconnected state by the axial movement of the piston and sleeve that follow the axial movement of the spool. , an electric drive means is coupled.

(2) Effect According to the above configuration, the spool is driven in the axial direction by the electric drive means according to the operating state of the engine.
When the hydraulic chamber is communicated with the hydraulic pressure supply path or the hydraulic release path, the piston moves in the axial direction in response to the hydraulic pressure supply to the hydraulic chamber or the hydraulic pressure release, and the sleeve also moves in the axial direction, thereby causing the hydraulic pressure to flow into the hydraulic chamber. The communication state of the hydraulic pressure supply path or the hydraulic pressure release path of The phase can be controlled steplessly according to the amount of axial movement of the spool.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings. First, in FIG. 1, a camshaft 1 for opening and closing an intake valve or an exhaust valve (not shown) is rotatably supported by an engine body 2. A pulley 4 as a timing wheel around which a timing belt 3 for transmitting rotational power from a crankshaft (not shown) of the engine is wound, and the camshaft 1 are arranged so that the phase of the pulley 4 and the camshaft 1 is They are interlocked and connected via timing changing means 5 that allows the timing to be shifted.

The timing change means 5 includes a rotating shaft 6 coaxially connected to the camshaft 1 and a housing 7 that is integrally provided with the pulley 4 and coaxially surrounds the rotating shaft 6.
and a piston 8 that faces the hydraulic chamber 18 at one end in the axial direction and is disposed coaxially with the housing 7 and the rotating shaft 6 while being biased toward one side in the axial direction by a spring 32, and restricts the amount of movement of the piston 8. It includes a servo valve 9 and a phase adjustment mechanism 10 that interlocks and connects the piston 8, pulley 4, and rotating shaft 6 to change the rotational phase of the pulley 4 and rotating shaft 6 in accordance with the axial movement of the piston 8.

The rotating shaft 6 is formed into a cylindrical shape with a bottom integrally having a shaft portion 6a at its closed end, and by screwing a bolt 11 passing through the closed end to the camshaft 1, the shaft portion 6a is connected to the camshaft shaft. Coaxially connected to the end of 1. Pulley 4 is timing belt 3
An outer ring part 4a around which the inner ring part 4a is wound, and an inner ring part 4b coaxial with the outer ring part 4a are connected to each other by a connecting plate part 4c. Further, the housing 7 is coaxially and integrally connected to one end of the inner ring portion 4b of the pulley 4, and is formed in a cylindrical shape with a bottom. An annular plate-shaped end plate 12 that covers the outer edge of the closed end of the rotating shaft 6 is fixed to the other end of the inner ring portion 4b, and the inner circumference of this end portion 12 and the outer circumference of the shaft portion 6a of the rotating shaft 6 are fixed. A seal member 13 is interposed between them. Further, a bearing 14 is interposed between the inner surface of the inner ring portion 4b and the outer surface of the rotating shaft 6 at a portion near the end plate 12. This bearing 14 is interposed between the inner ring part 4b and the rotating shaft 6 such that one end of the outer ring engages with the inner ring part 4b and the other end of the inner ring engages with the rotating shaft 6, Therefore, the pulley 4 and the housing 7 are prevented from moving relative to the rotating shaft 6, that is, the camshaft 1 in the axial direction, but are allowed to rotate relative to the axis.

A through hole 15 is bored in the center of the closed end of the housing 7, and the piston 8 has a cylindrical portion 8a that slides on the inner surface of the through hole 15, a ring portion 8b that slides on the inner surface of the housing 7, and a dish-shaped portion. A sealing member 16 is fitted onto the outer surface of the cylindrical portion 8a to slide on the inner surface of the through hole 15, and a sealing member 17 that slides on the inner surface of the housing 7 is fitted on the outer surface of the ring portion 8b. is fitted. As a result, a hydraulic chamber 18 is defined between the housing 7 and one end of the piston 8 between the seal members 16 and 17, and when hydraulic pressure is supplied to the hydraulic chamber 18, the piston 8 is pushed toward the other side in the axial direction. Moreover, both seal members 1
6 and 17 are of a piston ring type having a cut in a part in the circumferential direction, and by using such type of seal members 16 and 17, it is possible to reduce the sliding resistance of the piston 8.

The piston 8 is integrally provided with a support cylinder part 8d extending from the ring part 8b toward the camshaft 1 to be inserted between the inner ring part 4b of the pulley 4, the housing 7, and the rotating shaft 6, This support cylinder portion 8d, the inner ring portion 4b of the pulley 4, and the rotating shaft 6 are interlocked and connected via a phase adjustment mechanism 10.

In FIGS. 2a and 2b, the phase adjustment mechanism 10
is a guide groove 19 provided on the outer surface of the rotating shaft 6;
a guide hole 20 provided in the inner ring portion 4b of the pulley 4 corresponding to the guide groove 19; a roller pin 21 pivotally supported by the support cylinder portion 8d to fit in the guide groove 19;
A roller pin 2 that is coaxial with the roller pin 21 and pivotally supported by the support cylinder portion 8d so as to fit into the guide hole 20.
It consists of 2. Moreover, the guide groove 19 and the guide hole 2
0 are formed so as to be inclined with respect to the axes of the rotating shaft 6 and the pulley 4 and intersect with each other. Accordingly, those roller pins 21 and 22 are inserted into the guide groove 19.
The rotating shaft 6 and the pulley 4 rotate in opposite directions by rolling in the guide hole 20. As a result, the phases of the rotating shaft 6, the camshaft 1, and the pulley 4 change. That is, when the piston 8 moves to the position closest to the camshaft 1, the relative circumferential position of the rotating shaft 6 and the pulley 4 becomes as shown in FIG. , the relative positions of the rotating shaft 6 and the pulley 4 in the circumferential direction are as shown in FIG. 2b. Moreover, such phase adjustment mechanisms 10 are arranged at a plurality of locations, for example, three locations, at equal intervals in the circumferential direction of the piston 8.

Referring again to FIG. 1, the guide hole 2 is provided on the outer periphery of the inner ring portion 4b of the pulley 4 near the housing 7.
A cylindrical cover 23 is fitted to prevent the roller pin 22 from falling off from the cover 2.
3 is fixed to the inner ring portion 4b. Moreover, seal members 25 and 26 are interposed between the inner ring portion 4b and the connecting plate portion 4c and the cover 23 on both sides of the guide hole 20. In addition, the rotating shaft 6 has an inner part inside the rotating shaft 6.
and a breath hole 24 communicating between the housing 7
is drilled.

The servo valve 9 includes a cylindrical sleeve 29 that is slidably fitted onto the rotating shaft 6, and a cylindrical spool 30 that is slidably fitted into the sleeve 29. Further, a spring 32 is compressed between the sleeve 29 and the closed end of the rotating shaft 6.
2, the sleeve 29 is biased in the direction in which one end of the sleeve 29 comes into contact with the connecting plate portion 8c of the piston 8, and the piston 8 is also biased toward one side in the axial direction against the hydraulic pressure of the hydraulic chamber 18. be done.

Further, a support member 27 is fixed to the engine body 2 so as to cover the timing change means 5, and an electric drive means 28 is fixed to the support member 27 coaxially with the timing change means 5. Twenty-eight drive shafts 31 are connected to the spool 30. Furthermore, a cap 33 that covers the through hole 15 is fixed to the closed end of the housing 7.
The drive shaft 31 passes through the center of the cap 33 so as to be freely movable in the axial direction, and a seal member 34 is interposed between the drive shaft 31 and the cap 33.

The electric drive means 28 operates the drive shaft 31 to an arbitrary position in the axial direction according to an input electric signal, and includes, for example, a DC or AC servo motor, a stepping motor, a linear motor,
An electric cylinder, a linear solenoid, a rotary solenoid, a piezoelectric motor, a laminated piezoelectric actuator, etc. are used.

The engine body 2 includes a first pump connected to the hydraulic pump 36.
A hydraulic pressure supply path 37 is formed in the camshaft 1, and an annular groove 38 communicating with the first hydraulic pressure supply path 37 is formed in the outer surface of the camshaft 1, and a second hydraulic pressure supply path 39 communicating with the annular groove 38 is formed in the camshaft 1. Further, the rotating shaft 6 is provided with a third hydraulic pressure supply path 40 that is always in communication with the second hydraulic pressure supply path 39, and the inner surface of the rotating shaft 6 is provided with an annular groove 41 that communicates with the third hydraulic pressure supply path 40. A pair of annular seal members 42 and 43 are interposed between the camshaft 1 and the engine body 2 with the annular groove 38 of the camshaft 1 interposed therebetween, and second and third hydraulic pressure supply paths are provided between the camshaft 1 and the rotating shaft 6. An annular seal member 44 is interposed to maintain the communication state between 39 and 40.

The sleeve 29 is provided with an oil hole 45 that is always in communication with the annular groove 41 regardless of its axial position with respect to the rotating shaft 6. An annular groove 46 is bored on the inner surface. Further, in the sleeve 29 and the connecting plate portion 8c in contact with the sleeve 29, an oil passage 47 is provided which communicates the annular groove 46 with the hydraulic chamber 18.
is drilled. Furthermore, the bolt 11 and the camshaft 1 are provided with a hydraulic release path 4 leading to the oil tank 48.
9 is drilled.

An annular groove 50 is bored on the outer surface of the spool 30, and the annular groove 50 extends along the axial direction of the spool 30.
The width of the annular groove 5 is between the oil hole 45 and the annular groove 46.
It is set to the extent that communication is possible with 0. This spool 30 has a blocking position where only the oil hole 45 communicates with the annular groove 50, a supply position where the oil hole 45 and the annular groove 46 communicate with each other via the annular groove 50, and a supply position where the oil hole 45 and the annular groove 46 communicate with each other via the annular groove 50.
It is movable between three axial relative positions with respect to a release position that communicates the hydraulic pressure release path 49 with the hydraulic pressure release path 49. Further, a stopper 51 projecting radially inward is integrally provided at the end of the sleeve 29 on the camshaft 1 side, and this stopper 51 comes into contact with the spool 30 to restrict relative movement in the axial direction.

Next, the operation of this embodiment will be explained. Rotational power transmitted from the engine crankshaft via the timing belt 3 is transmitted from the pulley 4 to the camshaft 1 via the timing change means 5.
In response to the rotation of the camshaft 1, an intake valve or an exhaust valve is driven to open or close.

In order to change the opening/closing timing of the intake valve or the exhaust valve, an electric signal is input to the electric drive means 28 to move the drive shaft 31 to a desired position. For example, in FIG. 1, the drive shaft 31 is in a state in which the drive shaft 31 is fully extended, the relative axial positions of the sleeve 29 and the spool 30 are in the blocking position where only the annular groove 50 communicates with the oil hole 45, and the phase adjustment mechanism 10 is in the state shown in FIG. 2a. Then, when the drive shaft 31 is contracted and the spool 30 is moved to one side in the axial direction (left side in FIG. 1), the annular groove 46 is brought to a release position communicating with the hydraulic release path 49. Therefore, the hydraulic pressure in the hydraulic chamber 18 is released, the sleeve 29 and the piston 8 are moved in one direction in the axial direction by the spring force of the spring 32, the rotation shaft 6 and the pulley 4 are rotated relative to each other by the phase adjustment mechanism 10, and the intake valve Or the opening/closing timing of the exhaust valve changes. Moreover, in response to the movement of the sleeve 29 in one direction in the axial direction,
The spool 30 moves relative to the other side in the axial direction with respect to the sleeve 29, and the relative positions of the spool 30 and the sleeve 29 in the axial direction become the blocking position. Therefore, the amount of movement of the piston 8 is determined according to the amount of movement of the spool 30 in the axial direction, and the amount of advance or delay of the opening/closing timing is determined accordingly. Stepless control is possible.

During such operation, since the seal members 16 and 17 fitted to the piston 8 are of the piston ring type, the sliding resistance is low, and therefore the operation of the piston 8, that is, the adjustment operation of the phase adjustment mechanism 10, is quickly performed. It can be done.

Further, when the servo valve 9 is in the cutoff position, when the drive shaft 31 is moved to the other side in the axial direction by the electric drive means 28 and the spool 30 is relatively operated from the cutoff position to the other side in the axial direction, the annular groove 50 is moved. The oil hole 45 and the annular groove 46 are in communication with each other at the supply position, and the hydraulic pressure from the hydraulic pump 36 is supplied to the hydraulic chamber 18.
As a result, the piston 8 is pushed and driven toward the other side in the axial direction against the spring force of the spring 32. As the piston 8 moves to the other side in the axial direction, the rotating shaft 6 and the pulley 4 rotate relative to each other due to the action of the phase adjustment mechanism 10, and the opening/closing timing of the intake valve or the exhaust valve changes. Furthermore, since the sleeve 29 also moves in accordance with the axial movement of the piston 8, the relative axial positions of the spool 30 and the sleeve 29 are at the blocking position. Therefore, spool 3
The amount of movement of the piston 8 is determined according to the amount of movement of 0, and the opening/closing timing is controlled steplessly. Moreover, due to the breath hole 35 provided in the rotating shaft 6,
The back pressure between the piston 8 and the rotating shaft 6 is quickly released, allowing the piston 8 to operate more quickly.

In this timing changing means 5, the housing 7 is integrally connected to the pulley 4 supported by the rotating shaft 6 via a bearing 14, and the phase adjustment mechanism 10 is also disposed at a portion corresponding to the pulley 4. Therefore, even though the housing 7 has a cantilever support structure, there is no need to support the closed end side, that is, the front end side of the housing 7 with the rotating shaft 6. Therefore, there is no need to provide a portion of the rotating shaft 6 that passes through the connecting plate portion 8c of the piston 8 and supports the tip of the housing 7, and the pressure receiving area of the piston 8 facing the hydraulic chamber 18 can be made relatively large. Therefore, the operation of the piston 8, that is, the operation of the phase adjustment mechanism 10 can be made quick.

In the above embodiment, the guide groove 1 provided on the rotating shaft 6
9. Although the phase adjustment mechanism 10 is configured by the guide hole 20 provided in the pulley 4 and the roller pins 21, 22, the same effect can be obtained even if the rotating shaft 6 and the piston 8 and the piston 8 and the pulley 4 are connected by helical splines, respectively. A phasing mechanism can be configured to function. Further, one of the rotating shaft 6 and the piston 8 and the piston 8 and the pulley 4 are connected with a structure that prevents relative rotation, and the other is connected with a structure that allows relative rotation according to the axial movement of the piston 8. You can also do this.

C. Effects of the Invention As described above, according to the present invention, the hydraulic chamber facing one end in the axial direction of the piston, the hydraulic pressure supply path, and the hydraulic pressure release path are interlocked and connected to the piston, and are connected within the rotating shaft. A servo valve is interposed, which includes a sleeve that is slidably fitted and a spool that is slidably fitted to the sleeve and capable of relative axial movement. The communication state between the hydraulic chamber and the hydraulic pressure supply path or the hydraulic release path is switched to a disconnected state by axial movement of a piston and a sleeve that follow the axial movement of the spool, and an electric drive means is connected to the spool. Therefore, by activating the electric drive means with an electric signal, the piston is moved by an amount corresponding to the amount of movement of the spool.
By steplessly adjusting the amount of relative rotation between the timing wheel and the camshaft, it is possible to steplessly control the opening/closing timing of the intake valve or the exhaust valve.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal sectional view, and FIG. 2 is an enlarged sectional view taken along the line -- in FIG. DESCRIPTION OF SYMBOLS 1... Camshaft, 4... Pulley as a timing wheel, 6... Rotating shaft, 8... Piston, 9... Servo valve, 10... Phase adjustment mechanism, 18... Hydraulic chamber, 28... Electric drive Means, 29...Sleeve,
30... Spool, 37, 39, 40... Hydraulic supply path, 49... Hydraulic release path.

Claims (1)

[Claims] 1. A cylindrical rotating shaft connected to the camshaft; an adjustable shaft that is disposed coaxially with the rotating shaft and is prevented from moving relative to the rotating shaft in the axial direction and allows relative rotation around the axis, and is driven from the crankshaft. a timing wheel; a piston that is disposed coaxially with the rotating shaft and the timing wheel, with a hydraulic chamber facing one end in the axial direction, and is biased by a spring toward one side in the axial direction; In a valve train for an internal combustion engine, the hydraulic chamber faces one end of the piston in the axial direction; , a sleeve interlocked and connected to the piston and slidably fitted into the rotating shaft, and a sleeve that is movable relative to the shaft and slidable on the sleeve between the hydraulic pressure supply path and the hydraulic release path. A servo valve consisting of a spool to be fitted is interposed, and the servo valve follows the axial movement of the spool to change the state of communication between the hydraulic chamber and the hydraulic pressure supply path or the hydraulic release path due to the axial movement of the spool. 1. A valve train for an internal combustion engine, which is configured to be switched to a shut-off state by axial movement of a piston and a sleeve, and characterized in that an electric drive means is connected to a spool.