JPH03225004A - Internal combustion engine valve timing control device - Google Patents

Abstract

PURPOSE:To arbitrarily set the shift position of a cylindrical gear in the axial direction by installing a hydraulic control mechanism for controlling the hydraulic pressure in a pressure chamber according to the engine operation state in a hydraulic circuit. CONSTITUTION:A cylindrical gear 13 which determines the relative turning phase between a sprocket 5, which is driven by an engine,and a camshaft 1 is shifted in the axial direction by a driving mechanism through a hydraulic pressure introduced into a pressure chamber 16 by a hydraulic circuit 17. A hydraulic control mechanism 25 for controlling the hydraulic pressure in the pressure chamber 16 according to the engine operation state is installed in the hydraulic circuit 17. Accordingly, the shift position in the axial direction of the cylindrical gear 13 can be set arbitrarily by properly controlling the hydraulic pressure in the pressure chamber 16 by the hydraulic control mechanism 25. Accordingly, the relative turning position between the camshaft 1 and the sprocket 5 can be finely controlled according to the engine operation state.

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 operating conditions.

BACKGROUND OF THE INVENTION Various conventional valve timing control devices of this type have been provided, such as U.S. Pat. No. 4,535.
, No. 731 is known.

Briefly, a camshaft that controls the opening and closing of intake and exhaust valves has external teeth formed on the outer periphery of its front end.

On the other hand, the outer cylinder, which is placed and supported on the outside of the front end of the camshaft, is equipped with a sprocket on its outer periphery through which the rotational force of the engine is transmitted via a timing chain, and internal teeth are formed on its inner periphery. . A cylindrical gear in which at least one of the teeth on the inner and outer peripheries is helical is meshed between the inner teeth and the outer teeth of the camshaft. By moving the camshaft in the axial direction using the hydraulic pressure of the hydraulic circuit and the spring force of the compression spring according to the engine operating condition, the camshaft is rotated relative to the sprocket to control the opening and closing timing of the intake and exhaust valves. It is supposed to be done.

Problems to be Solved by the Invention However, in the conventional valve timing control device, the hydraulic pressure in the pressure chamber is controlled by high hydraulic pressure to move the cylindrical gear in one direction against the spring force of the compression spring. There is only a two-step ON-OFF switching control: and low oil pressure control for moving the cylindrical gear in the other direction by the spring force of the compression spring. Therefore, there are only two relative rotational positions between the camshaft and the sprocket, the maximum forward and reverse rotational positions, and therefore the valve timing cannot be accurately controlled depending on the engine operating state.

Means for Solving the Problems The present invention was devised in view of the above-mentioned conventional situation, and
In particular, it is characterized in that the hydraulic circuit is provided with a hydraulic control mechanism that controls the hydraulic pressure in the pressure chamber according to the engine operating state.

Effects According to the present invention having the above configuration, the hydraulic pressure in the pressure chamber can be appropriately controlled by the hydraulic control mechanism to arbitrarily set the axial movement position of the cylindrical gear to a predetermined position. It becomes possible to finely control the relative rotational position with respect to the engine operating state.

EXAMPLE Hereinafter, an example of the present invention will be described in detail with reference to FIGS. 1 and 2. Note that this embodiment also uses DOHC as in the conventional example.
This figure shows what is applied to a type internal combustion engine.

That is, 1 in FIG. 2 is the cam bearing 2 of the cylinder head 2.
3 is a cylindrical support member fixed by a bolt 4 inserted in the axial direction to one end la side of the camshaft l; 5 is a cylindrical support member disposed on the outer periphery of the support member 3; A sprocket is a driven force body to which driving force is transmitted from the crankshaft of a timing chain,
This sprocket 5 has inner teeth formed on the front inner periphery of an outer cylinder 6.

The support member 3 has a base portion 3a that is connected to the camshaft and an end portion 1a.
The cylindrical front end 3b having outer teeth on the outer periphery is shorter than the outer cylinder 6 of the sprocket 5.

The sprocket 5 consists of the outer cylinder 6 and a gear part 8 connected to the outer cylinder 6 via a fixing bolt 7, and is rotated by one end 1a of the camshaft 1 through a central hole 8a of the gear part 8. freely supported.

The outer cylinder 6 has an annular portion 9 caulked and fixed to the inner periphery of the front end side, and a step-shaped substantially disc-shaped holding member 10 is fixed to the front end surface of the annular portion 9 with bolts 12 via an O-ring 11. has been done.

Furthermore, a cylindrical gear 13 that is movable in the axial direction is arranged between the support member 3 and the outer cylinder 6.

This cylindrical gear 13 has two gear components 13a formed by cutting and dividing a long gear in the direction perpendicular to the axis.

13b, and both gear components 13a, 13b are connected by a spring 14 mounted in the front gear component 13a and a connecting pin I5.

In addition, internal and external teeth, both of which are helical teeth, are formed on the inner and outer peripheries of each gear component 13a, 13b, respectively, and the inner teeth of the outer cylinder 6 and the front end of the support member are formed on these external teeth. The outer teeth of portion 3b are spirally engaged.

Further, the front gear component 13a has an annular portion 9 at the outer edge of the front end.
The gear component 13b on the rear side hits the inner end surface of the annular projection 8b of the gear portion 8, and its movement in the maximum forward direction (to the left in the figure) is restricted. The movement of the cylindrical gear 13 in the maximum backward direction (rightward in the figure) is restricted.

Further, the cylindrical gear 13 is moved in the longitudinal axial direction by a drive mechanism. This drive mechanism has an annular portion 9
A pressure chamber 16 is formed on the inner end face of the front gear component 13a to move the cylindrical gear I3 backward by internal hydraulic pressure, and a hydraulic circuit 17 introduces hydraulic pressure into the pressure chamber 16. 7. A compression spring 18 is provided between the rear gear component 13b and the gear part 8 to bias the cylindrical gear 13 forward.

The hydraulic circuit 17 has an oil supply passage 2 whose upstream end communicates with an oil pump 19 and which passes through the cylinder head 2 and the cam bearing 2a and opens into the radial passage 20 of the cam shirt 1.
1, and an oil passage 22 formed through the bolt 4 in an axial direction.

The oil supply passage 21 is provided with an electromagnetic switching valve 24 that switches the passage of pressure oil fed from the oil pump 19 to either the oil supply passage 21 or the discharge passage 23 depending on the engine operating state. Further, the oil passage 22 has one end 22a open to the radial passage 20, and the bolt head 4a.
The other stepped end 22b of the support member 3 communicates with the pressure chamber 16 through the hollow interior 3c of the support member 3.

Furthermore, a hydraulic control mechanism 25 for controlling the hydraulic pressure within the pressure chamber 16 is provided on the outer end side of the support member 3 . This hydraulic control mechanism 25 includes a cylindrical valve body 26 that is disposed in a bottomed cylindrical portion 10a in the center of the holding member IO so as to be able to move forward and backward.
, a spherical control valve 27 disposed inside the valve body 26 , and an electromagnetic actuator 28 that presses the valve body 26 .

As shown in FIG. 1, the valve body 26 has one end 26a.
A communication hole 1 is formed in the outer circumferential wall of the cylindrical portion 10a in the radial direction.
0b to the hollow interior 3c and the passage section 26 inside itself.
A pressure oil discharge port 26d is formed on the outer periphery near the covered tip 26c to communicate the passage 26b with the outside. In addition, valve body 2
6 and the bottom of the bottomed cylindrical portion 10a, the fill spring 29 is biased in a direction to open the communication hole 10b.

The control valve 27 is configured to sit on and off an arc-shaped seat portion 30a at the end of the cylindrical passage forming portion 3o provided inside one end side of the valve body 26, and to control the amount of opening of the passage portion 26b. , and the inner end of the tip portion 26c, the control spring 31 is biased in a direction to close the passage portion 26b. The spring force of this control spring 31 is
It is arbitrarily set depending on the relative relationship with the oil pressure in the passage portion 26c.

The electromagnetic actuator 28 is controlled by an ON-OFF signal from a controller 32 having a built-in computer, and when the ON signal is turned on, the drive port 28a closes to the valve body 26.
Press the tip end 26c of the connecting hole 10b with one end 26a.
In other words, the valve body 26 is moved in the closing direction. The controller 32 detects the current engine operating state based on information signals from a crank sensor, an air flow meter, etc. (not shown), and also controls the electromagnetic switching valve 24 to turn ON/OFF based on the detection signal. There is.

The operation of this embodiment will be explained below. First, when the controller 32 outputs an OFF signal to the electromagnetic switching valve 24 and the electromagnetic actuator 28, respectively, when the engine load is low, the oil pump 19 and the discharge passage 23 communicate with each other, and the oil supply passage 21 is closed. Meanwhile, as shown in the figure, the valve body 26 advances leftward in the figure by the spring force of the fill spring 29 to open the communication hole 10b. Therefore, the pressure oil pumped from the oil pump 19 is discharged from the discharge passage 23 and is not supplied into the pressure chamber 16, so that the pressure inside the pressure chamber 16 becomes low. Therefore, the cylindrical gear I3 is
The sprocket 5 is moved forward by the spring force of the compression spring 18 until it hits the annular portion 9, and the sprocket 5 is determined at this position.
For example, the closing time of the intake valve is controlled to be delayed depending on the relative rotational phase between the intake valve and the camshaft 1. Note that most of the pressure oil in the pressure chamber 16 is retained within the pressure chamber 16 because the passage portion 26b is closed by the control valve 27.

On the other hand, when the engine operating state shifts from, for example, a low load region to, for example, a medium load region, an ON signal is output to the electromagnetic switching valve 24, and the pressure oil from the oil pump 19 flows only into the oil supply passage 21 side. The oil is introduced from the oil passage 22 through the hollow interior 3c into the pressure chamber 16, where the oil pressure increases. Therefore, the cylindrical gear 13 moves backward (to the right in the figure) against the spring force of the compression spring 18, and also moves against the spring force of the compression spring 18.
The spring load of will also increase. Therefore, when the camshaft 1 and sprocket 5 reach a predetermined target relative rotation position as the cylindrical gear 13 moves backward, the oil pressure in the pressure chamber 16 increases due to the relative pressure with the spring force of the compression spring 18. The control valve 27 is pushed open against the spring force of the control spring 31 through the hollow interior 3c, the communication hole 10b1 and the passage portion 26b, and a part of the pressure oil is discharged to the outside from the pressure oil discharge port 26d.
The oil pressure within the pressure chamber 16 is maintained constant. As a result, the camshaft 1 and the sprocket 5 are maintained at the target relative rotational positions, and desired valve timing control becomes possible.

Furthermore, when the load shifts to a high load range, an ON signal is also output to the electromagnetic actuator 28, and the valve body 26 is pushed by the drive rod 28a against the spring force of the coil spring 29 to open the communication hole lOb. Obstruction. Therefore, the oil pressure in the pressure chamber 16 further increases, and the cylindrical gear 13
is further moved in the rearward direction against the spring force of the compression spring 18. As a result, the camshaft 1 and the sprocket 5 are further rotated relative to each other, so that, for example, the closing timing of the intake valve is controlled to be advanced.

In this embodiment, the forward movement of the cylindrical gear 13 is performed by the compression spring 18, but the present invention is not limited to this, and a separate pressure chamber may be provided at the location where the compression spring 18 is disposed to reduce the hydraulic pressure in the pressure chamber. It is also possible to do this by

In this case, it is also possible to provide a hydraulic control mechanism similar to that described above in the hydraulic circuit that introduces hydraulic pressure into the pressure chamber. In this way, it becomes possible to more precisely control the movement position of the cylindrical gear 13 in both the forward and backward directions.

Further, the electromagnetic switching valve 24 and the discharge passage 23 can also be eliminated.

Effects of the Invention As is clear from the above explanation, according to the present invention, the hydraulic circuit is provided with a hydraulic control mechanism that controls the hydraulic pressure in the pressure chamber according to the engine operating state, so that the movement of the cylindrical gear in the axial direction is prevented. The position can be set arbitrarily. As a result, the relative rotational position between the camshaft and the rotated body can be maintained at a desired position, and the valve timing can be controlled with high precision according to the engine operating state.

[Brief explanation of drawings]

FIG. 1 is an enlarged view of part A in FIG. 2, and FIG. 2 is a sectional view showing an embodiment of a valve timing control device according to the present invention. 1... Kamunyabuto, 5... Sprocket (rotated body), 13... Cylindrical gear, 16... Pressure chamber, 17...
- Hydraulic circuit, 25... Hydraulic control mechanism.

Claims (1)

[Claims] (1) A cylindrical gear that determines the relative rotational phase between the rotated body driven by the engine and the camshaft, and the cylindrical gear is moved in the axial direction via hydraulic pressure introduced into the pressure chamber by a hydraulic circuit. What is claimed is: 1. A valve timing control device for an internal combustion engine, characterized in that the hydraulic circuit is provided with a hydraulic control mechanism for controlling the hydraulic pressure in the pressure chamber in accordance with the operating state of the engine.