JPH02227507A - Valve timing control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To shorten a cam shaft by forming a driving mechanism of a phase setting mechanism located between a body to be driven and the cam shaft by a flow control valve and an oil pressure change-over valve provided adjacent to the phase setting mechanism. CONSTITUTION:A cylindrical supporting member 3 is fixed to one end part of a rotatably journalled cam shaft 1 with a bolt 4, and a sprocket 5 is arranged on the outer periphery of the supporting member 3. A phase setting mechanism 10 consisting of two gear components 11a, 11b and having a cylindrical gear 11 axially moved by a driving mechanism, a spring 12 and a connecting pin 13 connecting both the components 11a, 11b, is arranged in a space part defined in the sprocket 5. An inner gear tooth on the inner periphery of an external cylinder 6 and an outer gear tooth of front end part 3b of the supporting member are mated with helical gears formed on the inner and outer peripheries of each component 11a, 11b. The driving mechanism is composed of a hydraulic circuit 16 provided with a flow control valve 18, and an oil pressure change-over valve 19 arranged in the front end part 3b of the supporting member, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a valve timing control device that variably controls the opening and closing timing of intake and exhaust valves of an internal combustion engine in accordance with engine operating conditions.

2. Description of the Related Art A conventional valve timing control device of this type is known, for example, as disclosed in Japanese Utility Model Application Laid-open No. 16706/1983.

To explain the outline, a timing pulley, which is a driven body, is moved relative to a camshaft that has a cam that opens and closes the intake and exhaust valves of a Do) Ic type internal combustion engine via a phase setting mechanism consisting of a cylindrical gear, a pressure chamber, etc. The cylindrical gear of the phase setting mechanism is rotatably supported, and the cylindrical gear of the phase setting mechanism is moved in the axial direction by hydraulic pressure supplied to the pressure chamber by a drive mechanism and the spring force of a spring. The drive mechanism includes a hydraulic circuit that is formed through the camshaft in an axial direction and communicates with the oil main gear rally midway, and a hydraulic circuit that is disposed at the end of the camshaft opposite to the phase setting mechanism and supplies the pressure chamber. The engine is equipped with a flow control valve that controls the amount of oil that is supplied to the engine, and an electromagnetic actuator that is fixed to the cylinder and opens and closes the flow control valve in accordance with engine operating conditions.

When the electromagnetic actuator is de-energized, the flow control valve opens a relief passage using the force of the spring, drains the oil in the hydraulic circuit into the cylinder head, and cuts off the supply to the pressure chamber. When the actuator is energized, the plunge portion 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 angle phase of the valve to the timing boolean, the opening and closing timing of the intake and exhaust valves can be variably controlled.

Problems to be Solved by the Invention However, in the conventional device, the flow rate control valve is provided at the end of the camshaft opposite to the phase setting mechanism as described above, so the hydraulic path is long ( As the engine operating conditions change, the time required for the hydraulic pressure acting on the pressure chamber of the phase setting mechanism to be discharged from the flow control valve becomes longer.As a result, the operational response of the phase setting mechanism deteriorates and the valve timing cannot be controlled with high precision.

Moreover, as mentioned above, the flow control valve is located at the opposite end of the camshaft from the phase setting mechanism, so the length of the camshaft is essentially longer than that of a normal camshaft, which forces the overall length of the engine to be longer. .

Means for Solving the Problems The present invention has been devised in view of the above-mentioned conventional problems. In particular, the drive mechanism is provided at a predetermined location on the engine body,
It is characterized by comprising a flow control valve that opens and closes a hydraulic circuit depending on the engine operating state, and a hydraulic pressure switching valve that is provided near the phase setting mechanism and supplies and discharges hydraulic pressure to the phase setting mechanism. .

Effects According to the present invention having the above configuration, since the flow control valve is provided in the cylinder head of the engine, for example, instead of the camshaft as in the conventional case, it is of course possible to prevent the camshaft from becoming substantially longer. Since the hydraulic pressure switching valve is disposed near the phase setting mechanism, the hydraulic pressure can be rapidly supplied and discharged from the phase setting mechanism.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on FIGS. 1 to 3. It should be noted that this embodiment is also applied to a DOHC type internal combustion engine, similar to the conventional example.

That is, ■ is a camshaft supported by a cam bearing 2a of the cylinder head 2, and 3 is one end l of the camshaft l.
A cylindrical support member is fixed by a bolt 4 inserted in the axial direction on the side a, and 5 is a driven member arranged on the outer periphery of the support member 3, to which driving force is transmitted by a timing boon from a crankshaft (not shown). This sprocket 5 has inner teeth formed on the front inner periphery of an outer cylinder 6.

Further, the supporting member 3 has a large diameter base portion 3a fitted into the seven rung portion 1b of the one end portion 1a of the camshaft, and a stepped small diameter cylindrical front end portion 3b having outer teeth on the outer periphery of the sprocket 5. It extends further in the axial direction than the outer cylinder 6, and forms an annular space 7 between the front end portion 3b and the outer cylinder 6.

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

As shown in FIG. 4, the sealing mechanism 8 includes a seal ring 8a having a substantially rectangular cross section that abuts the front edge of the sprocket outer cylinder 6, and an elastic body 0 that abuts the inner peripheral edge of the end plate 9. The ring 8b is in close contact with the ring 8b, thereby ensuring double sealing performance.

The phase setting mechanism 10 includes two gear structures tia and llb formed by cutting and dividing a long gear in a direction perpendicular to the axis.
A cylindrical gear 11 that is movable in the axial direction, and a spring 12 and a connecting pin 13 that are fitted into the front gear structure 11a and connect the gear structure 11a and the rear gear structure 11b. ing. Moreover, each gear structure 11a,
Inner teeth and outer teeth, both of which are helical teeth, are formed on the inner and outer peripheries of llb, respectively, and the inner teeth of the outer cylinder 6 and the outer teeth of the support member front end 3b mesh with these inner and outer teeth in a spiral manner. ing. Furthermore, the outer edge of the front end of the front gear structure 11a abuts against the support portion 9a provided on the inner surface of the end plate 9, and movement in the maximum forward direction (to the left in the figure) is restricted, and the front end It is movable rearward (to the right in the figure) by the hydraulic pressure in an annular first pressure chamber 15 formed at the front end of the side, that is, the space 7 . On the other hand, the rear gear structure 1
1b abuts against the inner end surface 3d of the base 3a of the rear end support member 3, so that the maximum backward movement of the cylindrical gear 11 is restricted.

Moreover, the cylindrical gear 11 is driven by a drive mechanism. This drive mechanism is installed between a hydraulic circuit 16 that supplies and discharges hydraulic pressure to and from the first pressure chamber 15, the rear gear structure 11b, and the base 3a of the support member 3, and moves the cylindrical gear 11 forward. a compression spring 17 that biases the support member 3; a flow control valve 18 that is provided in the cylinder head 2 on the downstream side of the hydraulic circuit 16 to control the flow rate of hydraulic fluid flowing through the hydraulic circuit 16; and a front end of the support member 3. A hydraulic switching valve 19 is provided within the section 3b.

The hydraulic circuit 16 has an oil supply passage 2 whose upstream end communicates with an oil pump 40 and which passes through the cylinder head 2 and cam bearing 2a and opens into an annular passage 20 on the outer circumference of the camshaft l.
1, and an oil passage 22 formed through the bolt 4 in the internal axial direction and having a bent end 22a opening into the annular passage 20. Large diameter other end 22 of this oil passage 22
b opens into a second pressure chamber 23 defined between the bolt 4 head 4a and a valve body 28 of the hydraulic pressure switching valve 19, which will be described later. Further, in the front peripheral wall of the front end portion 3b of the support member 3, there are a plurality of communication holes 24 and 24, which communicate with the first pressure chamber 15.
... are drilled in the radial direction.

Further, an annular member 25 is provided on the front inner circumferential surface of the front end portion 3b of the support member 3 via a support ring 26, and an oil drain hole 27 is bored in the center of the annular member 25.

The hydraulic switching valve 19 has a front end portion 3 as shown in FIG.
the valve body 28 slidably housed in the axial direction in b;
The valve body 28 is installed between the valve body 28 and the annular member 25.
and a valve spring 29 that biases the pressure toward the second pressure chamber 23. The valve body 28 has a substantially cylindrical shape with a bottom,
The outer periphery of the disc-shaped bottom wall 28a comes into contact with the stopper ring 30 fitted to the inner periphery of the front end 3b, and the maximum movement toward the second pressure chamber 23 side (rightward in the figure) is restricted. There is.

Further, in the peripheral wall 28b rising from the peripheral edge of the bottom wall 28a, an annular groove 31 is formed in the communication hole 24 at the maximum rightward position.
A plurality of passage holes 32 are drilled in the radial direction and communicate with each other via.

The flow rate control valve 18 is disposed at the downstream end of a relief passage 33 branched from the hydraulic pressure supply passage 21, and includes a valve body 34 that opens and closes the relief passage 33, and an electromagnetic actuator 35 that opens and closes the valve body 34. The electromagnetic actuator 34 is driven and controlled by a controller 36 that detects the operating state of the engine based on output signals from a crank angle sensor, an air flow meter, and the like.

The operation of this embodiment will be explained below. First, when an OFF signal (de-energized) is output from the controller 36 to the electromagnetic actuator 35, for example when the engine is under low load, the valve body 3 of the flow control valve 18 as shown in FIG.
4 retreats to open the relief passage 33. For this reason,
Most of the hydraulic oil supplied from the oil pump to the oil pressure supply passage 21 through the oil main gear rally 40 is +71J.
- The oil is discharged from the oil passage 33 to the outside, and the amount of oil supplied to the oil passage 22 decreases. Therefore, the valve body 2 of the hydraulic switching valve 19
8, as shown in FIGS. 1 and 3, a stopper ring 30 is attached to the second pressure chamber 23 side by the spring force of the valve spring 29.
The communication hole 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 communication hole 24 through the passage hole 32 and the inside of the front end 3b to the outside from the oil discharge hole 27 as shown by the arrow.
The pressure chamber 15 enters a low pressure state. Therefore, the cylindrical gear I
t is biased to the leftmost position by the spring force of the spring 17, and the opening/closing timing of the intake and exhaust valves is controlled with good responsiveness according to the relative rotational phase between the sprocket 5 and the camshaft 1 determined at this position. Ru.

On the other hand, when the engine operating state changes from a low load range to a high load range, for example, and an ON signal is output to the electromagnetic actuator 35, the valve body 34 of the flow control valve 18 moves into the relief passage 33 as shown in FIG. Close.

Therefore, the hydraulic oil supplied to the oil pressure supply passage 21 flows into the second pressure chamber 23 from the other end 22b through the oil passage 22, and the pressure within the second pressure chamber 23 is increased. Therefore, the valve body 28 of the hydraulic switching valve 19 is pressed and slides in the direction shown in the figure against the spring force of the valve spring 29, and the communication between the communication hole 24 and the passage hole 32 is interrupted, and at the same time, the volume is expanded. The second pressure chamber 23 and the first pressure chamber 15 are communicated through a communication hole 24. Therefore, the hydraulic oil in the second pressure chamber 23 quickly flows into the first pressure chamber 15 as shown by the arrow, the first pressure chamber 15 becomes high pressure, and the entire cylindrical gear 11 is moved by the spring force of the spring 17. Move it to the right in the figure against the Therefore, the camshaft 1 rotates by a predetermined angle relative to the sprocket 5, and the opening/closing timing of the intake and exhaust valves is changed with good response.

Furthermore, since the flow control valve 18 is provided in the cylinder head 2 instead of at one end of the camshaft as in the conventional case, the overall length of the camshaft l can be substantially shortened. Furthermore, since rotational friction between the flow control valve 18 and the camshaft l as in the conventional case is completely avoided, wear of both 1 and 18 can be prevented.

Moreover, since the sealing mechanism 8 can provide a double seal between the first pressure chamber 15 and the outside, the sealing performance can of course be improved. Since the two parts are buffered, it is possible to effectively prevent collision noise caused by vibrations of the two parts 6 and 9.

The electromagnetic actuator 35 may have a stroke that is variable depending on the magnitude of the applied current, and the present invention is not limited to the phase setting mechanism 10 or drive mechanism in the above embodiment.

Effects of the Invention As is clear from the above explanation, according to the present invention, since the flow control valve is provided at a predetermined location on the engine body instead of on the camshaft, lengthening of the camshaft is prevented and the hydraulic path is The length can be shortened.

Moreover, since the hydraulic pressure switching valve is disposed near the phase setting mechanism, together with the shortening of the hydraulic path, the time for supplying and discharging hydraulic pressure to and from the phase setting mechanism is shortened, and operational responsiveness is improved. As a result, highly accurate control of valve timing becomes possible.

[Brief explanation of the drawing]

1 and 2 are sectional views of essential parts showing one embodiment of the present invention, FIG. 3 is an enlarged sectional view of essential parts of the invention, and FIG. 4 is an enlarged view of section A in FIG. 1. l...Camshaft, 2...Cylinder head (ll
(main body), 5... Sprocket (driven body), IO・
... Phase setting mechanism, 16... Hydraulic circuit, 17... Compression spring, 18... Flow rate control valve, 19... Hydraulic pressure switching valve. a Figure 4

Claims (1)

[Claims] (1) A phase setting mechanism that sets the relative angular phase between a driven body driven by an engine and a camshaft, and a drive mechanism that drives the phase setting mechanism via hydraulic pressure flowing through a hydraulic circuit. The drive mechanism includes a flow control valve that is provided at a predetermined location on the engine body and opens and closes the hydraulic circuit depending on the engine operating state, and a flow control valve that is provided near the phase setting mechanism to adjust the phase. A valve timing control device for an internal combustion engine, comprising a hydraulic pressure switching valve that supplies and discharges the hydraulic pressure to and from a setting mechanism.