JP2889586B2 - Valve timing control device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing control device that variably controls the opening / closing timing of intake / exhaust valves of an internal combustion engine in accordance with the operating state of the engine.

2. Description of the Related Art A known valve timing control device of this type is disclosed in, for example, Japanese Utility Model Laid-Open No. 62-16706.

In brief, a timing pulley, which is a driven body, is relatively rotated via a phase setting mechanism including a cylindrical gear and a pressure chamber on a camshaft having a cam for opening and closing an intake / exhaust valve of a DOHC type internal combustion engine. The cylindrical gear of the phase setting mechanism is freely rotatably supported, and is moved in the axial direction by hydraulic pressure supplied to the pressure chamber by a driving mechanism or spring force of a spring. The drive mechanism is formed in the inner axial direction of the camshaft and communicates with the oil main gallery on the way, and is disposed at an end of the camshaft opposite to the upper phase setting mechanism and supplied to the pressure chamber. A flow control valve for controlling the amount of oil to be supplied, and an electromagnetic actuator fixed to the cylinder for driving the flow control valve to open and close according to the operating state of the engine.

When the electromagnetic actuator is not energized, the flow control valve opens a relief passage by the spring force of the spring, discharges oil in the hydraulic circuit into the cylinder head and shuts off supply to the pressure chamber. When the actuator is energized, the plunger of the electromagnetic actuator presses the valve body of the flow control valve to close the relief passage, guides hydraulic pressure to the pressure chamber, moves the cylindrical gear in a predetermined axial direction, and moves the camshaft. By changing the relative angular phase with respect to the timing pulley, the opening / closing timing of the intake / exhaust valve is variably controlled.

However, in the conventional device, the sleeve fixed to the inner peripheral surface of the timing pulley and the outer peripheral surface of the camshaft are screwed to fit the sleeve. Since the inserted extension shaft is movable in the axial direction, the one end edge of the sleeve and the inner end surface of the flange portion of the extension shaft facing the one end edge may be vibrated while both are being driven. There is a possibility that a collision hitting sound may be generated.

Means for Solving the Problems The present invention has been devised in view of the above-described conventional problems, and has a rotating body driven by an engine and an intake / exhaust valve which is rotated by a rotating force transmitted from the rotating body. A camshaft having a cam to be opened, an end plate fixed to an end of the camshaft, and closing one end opening of an outer cylinder of the rotating body;
A valve timing control device that is interposed between the rotating body and the camshaft and includes a phase setting mechanism that converts a relative rotation phase between the rotating body and the camshaft as the shaft moves. Between the axial end surface of the outer cylinder of the rotating body and the outer peripheral side inner surface of the end plate axially opposed to the end surface,
It is characterized by providing a buffer mechanism.

According to the present invention having the above-described configuration, the vibration in the axial direction caused during the driving of the rotating body and the camshaft due to, for example, fluctuation in the rotational torque of the camshaft is effectively absorbed by the buffer mechanism. It is possible to prevent the hitting sound between the outer cylinder of the body and the end plate.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. This embodiment also shows an example applied to a DOHC type internal combustion engine as in the above-described conventional example.

That is, reference numeral 1 denotes a cam shaft which is supported by a cam bearing 2a of a cylinder head 2, and 3 denotes one end 1a of the cam shaft 1.
A cylindrical support member 5 fixed by bolts 4 inserted in the axial direction on the side is disposed on the outer periphery of the support member 3, and a sprocket as a driven body to which a driving force is transmitted by a timing chain from a crank shaft (not shown). The sprocket 5 has inner teeth formed on the inner periphery of the front side of the outer cylinder 6.

The support member 3 has a large-diameter base portion 3a fitted to the flange portion 1b of the camshaft one end portion 1a, and a stepped small-diameter cylindrical front end portion 3b having outer teeth on the outer periphery. The front end portion extends in the axial direction from the cylinder 6.
An annular space 7 is formed between 3b and the outer cylinder 6.

The sprocket 5 has a sprocket gear-side inner peripheral surface of the outer cylinder 6 fitted and supported on an outer peripheral surface of the base 3a of the support member 3, and a front end connected to one end of the space portion 7 via a buffer mechanism 8. An annular end plate 9 which is closed in a liquid-tight manner is provided. The inner peripheral edge of the end plate 9 is the front end of the support member 3.
3b is fixed by caulking to the tip edge 3c, and a phase setting mechanism 10 is disposed in the space 7.

As shown in FIG. 4, the cushioning mechanism 8 includes a seal ring 8a having a substantially rectangular cross section and abutting against the front end of the sprocket outer cylinder 6.
And the elastic O-ring 8b abutting on the inner peripheral edge of the end plate 9 so as to ensure double sealing.

The phase setting mechanism 10 includes an axially movable cylindrical gear 11 composed of two gear components 11a and 11b formed by cutting and dividing a long gear in a direction perpendicular to the axis, and a front gear component. 11
a and the rear gear structure 11b
And a connecting pin 13 for connecting the two. Further, on the inner and outer circumferences of the respective gear components 11a and 11b, there are formed internal teeth and external teeth of both helical teeth, respectively. The outer teeth of 3b are spirally meshed. Further, the front gear structure
The front end 11a has a front end outer edge abutting against a support portion 9a provided on the inner surface of the end plate 9 so that the movement in the maximum front direction (left direction in the figure) is restricted. It can be moved rearward (rightward in the figure) by the oil pressure in the annular first pressure chamber 15 formed in the above. On the other hand, the rear gear structure 11b abuts on the inner end face 3d of the base 3a of the rear end support member 3 so that the maximum rearward movement of the cylindrical gear 11 is restricted.

The cylindrical gear 11 is driven by a driving mechanism. This drive mechanism is provided in the first pressure chamber.
A hydraulic circuit 16 for supplying and discharging hydraulic pressure to and from a compression spring 17 mounted between the rear gear structure 11b and the base 3a of the support member 3 to urge the cylindrical gear 11 forward. A flow control valve 18 provided on the cylinder head 2 for controlling the flow rate of hydraulic oil flowing through the hydraulic circuit 16, and a hydraulic switching valve 19 disposed in a front end 3 b of the support member 3 are provided. I have.

The hydraulic circuit 16 has an oil supply passage 21 whose upstream end communicates with the oil pump 40, penetrates through the cylinder head 2 and the cam bearing 2a, and opens into an annular passage 20 on the outer periphery of the camshaft 1.
One end 22 a of the bolt 4 is formed to penetrate in the inner axial direction and is bent, and has an oil passage 22 opened to the annular passage 20. The other end 22b of the large diameter of the oil passage 22 is open to a second pressure chamber 23 defined between the head 4a of the bolt 4 and a valve body 28 of the hydraulic pressure switching valve 19, which will be described later. A plurality of communication holes 24 communicating with the first pressure chamber 15 are formed in the front peripheral wall of the front end 3b of the support member 3 in the radial direction. Further, an annular member 25 is provided on a front inner peripheral surface of the front end portion 3b of the support member 3 via a support ring 26.
An oil discharge hole 27 is formed in the center of the hole.

The hydraulic switching valve 19 has a front end 3b as shown in FIG.
The valve body 28 slidably accommodated in the axial direction therein, and a valve spring mounted between the valve body 28 and the annular member 25 for urging the valve body 28 toward the second pressure chamber 23. 29.
The valve body 28 has a substantially cylindrical shape with a bottom, and the outer peripheral edge of the disc-shaped bottom wall 28a contacts the stopper ring 30 fitted on the inner periphery of the front end 3b, and the second pressure chamber 23 side (right side in the drawing) Direction) is restricted. A plurality of passage holes 32 communicating with the communication hole 24 via the annular groove 31 at the maximum rightward position are formed in the peripheral wall 28b rising from the peripheral edge of the bottom wall 28a in the radial direction.

The flow control valve 18 is disposed at a downstream end of a relief passage 33 branched from the hydraulic supply passage 21, and is connected to the relief passage 33.
A valve body 34 for opening and closing the valve body, and an electromagnetic actuator 35 for opening and closing the valve body 34.
Is a controller that detects the operating state of the engine based on output signals from a crank angle sensor, an air flow meter, etc.
The drive is controlled by 36.

Hereinafter, the operation of this embodiment will be described. First, when an OFF signal (non-energized) is output from the controller 36 to the electromagnetic actuator 35 at a low engine load, for example, the valve body 34 of the flow control valve 18 moves backward as shown in FIG. Open 33. Therefore, the oil supply passage 21 from the oil pump through the oil main gallery 40
Most of the hydraulic oil supplied to the oil passage 22 is discharged from the relief passage 33 to the outside, and the amount of oil supplied to the oil passage 22 decreases. Therefore, the valve body 28 of the hydraulic pressure switching valve 19 is pressed by the spring force of the valve spring 29 toward the second pressure chamber 23 until it hits the stopper ring 30 as shown in FIGS.
24 and the passage hole 32 communicate with each other. Therefore, the hydraulic oil in the first pressure chamber 15 is quickly discharged from the oil discharge hole 27 to the outside through the communication hole 24 through the passage hole 32 and the inside of the front end 3b as shown by the arrow,
The first pressure chamber 15 enters a low pressure state. Therefore, the cylindrical gear
11 is urged to the leftmost position by the spring force of the spring 17,
Sprocket 5 and camshaft 1 determined at this position
The opening / closing timing of the intake / exhaust valve is controlled with good responsiveness in accordance with the relative rotational phase of the intake / exhaust valve.

On the other hand, when the engine operation state changes, for example, from a low load range to a high load range and an ON signal is output to the electromagnetic actuator 35, the valve element 34 of the flow control valve 18 closes the relief passage 33 as shown in FIG. Close. Therefore, the hydraulic oil supplied to the hydraulic pressure supply passage 21 flows through the oil passage 22 from the other end 22b into the second pressure chamber 23, and the pressure in the second pressure chamber 23 is increased. Therefore, the valve body 28 of the hydraulic pressure switching valve 19 is pressed and slid in the direction of the arrow in the drawing against the spring force of the valve spring 29, thereby blocking the communication between the communication hole 24 and the passage hole 32 and increasing the volume at the same time. The communication between the second pressure chamber 23 and the first pressure chamber 15 is established by the communication hole 24. Accordingly, the hydraulic oil in the second pressure chamber 23 quickly flows into the first pressure chamber 15 as shown by an arrow, and the first pressure chamber 15 becomes high pressure, and the entire cylindrical gear 11 is spring-loaded.
Move to the right in the figure against the spring force of 17. For this reason, the camshaft 1 rotates relative to the sprocket 5 by a predetermined angle, and the opening / closing timing of the intake / exhaust valve is changed with high responsiveness.

Further, since the flow control valve 18 is provided not at one end of the camshaft but at the cylinder head 2 as in the conventional case, the overall length of the camshaft 1 can be substantially shortened. Further, since the rotational friction between the flow control valve 18 and the camshaft 1 as in the prior art is completely avoided,
Wear of 18 can be prevented beforehand.

Moreover, since the first pressure chamber 15 and the outside can be double-sealed by the buffer mechanism 8, the sealing performance can be improved, and the outer cylinder 6 and the end plate 9 can be sealed by the O-ring 8b. Since these are buffered, it is possible to effectively prevent a collision sound caused by the vibration of both 6, 9 and the like.

Note that the electromagnetic actuator 35 may have a variable stroke according to the magnitude of the applied current, and the present invention is not limited to the phase setting mechanism 10 and the driving mechanism in the above embodiment.

Advantageous Effects of the Invention As apparent from the above description, according to the present invention, the vibration in the axial direction between the outer cylinder of the rotating body and the end plate can be effectively absorbed by the buffering action of the buffering mechanism. , Can be prevented from being hit.

[Brief description of the drawings]

1 and 2 are cross-sectional views of an essential part showing an embodiment of the present invention, FIG. 3 is an enlarged sectional view of an essential part of the present invention, and FIG. 4 is an enlarged view of a part A of FIG. DESCRIPTION OF SYMBOLS 1 ... Camshaft, 2 ... Cylinder head (engine body), 5 ... Sprocket (rotating body), 8 ... Bumper mechanism, 10 ... Phase setting mechanism, 16 ... Hydraulic circuit, 17 ... Compression spring, 18… Flow control valve, 19… Hydraulic switching valve.

Claims (1)

(57) [Claims] A camshaft having a rotating body driven by an engine, a cam for opening and closing an intake / exhaust valve by a rotating force transmitted from the rotating body, and fixed to an end of the camshaft; An end plate that closes one end opening of the outer cylinder of the rotator, and a rotary shaft and a camshaft are interposed between the rotator and the camshaft to change the relative rotation phase between the rotator and the camshaft as the shaft moves. A valve timing control device provided with a phase setting mechanism, wherein a cushioning mechanism is provided between an axial end surface of an outer cylinder of the rotating body and an outer peripheral inner surface of an end plate axially facing the end surface. A valve timing control device for an internal combustion engine, comprising: