KR20020054012A - Variable valve timing device for engine - Google Patents

Abstract

PURPOSE: A variable valve timing device of an engine is provided to vary valve timing by rotating a housing according to the motion of a piston and varying a phase of a cam shaft. CONSTITUTION: A variable valve timing device of an engine has an operating unit(60) coupled to a sprocket(22) of a cam shaft(20) and controlling the variable timing of a valve. The operating unit(60) includes a housing(61) integrally coupled to the sprocket(22), a cylinder(62) rotatably connected to the housing(61) and having an advance chamber(64) and a retard chamber(65) communicated with an oil passage(63), a piston(66) for reciprocating in the center of the cylinder(62), and a connection pin(67) for rotating the housing(61) according to the motion of the piston(66).

Description

VARIABLE VALVE TIMING DEVICE FOR ENGINE

The present invention relates to a variable valve timing apparatus of an engine, and more particularly, by using a piston-type operating means, as the piston moves from side to side, the housing rotates in the circumferential direction to change the phase of the camshaft so that the valve timing is simple. It relates to a variable valve timing apparatus of an engine capable of varying.

In general, the valve opening and closing timing of the engine, that is, valve timing (Valve Timing), is to open and close the valve before or after the top dead center or the bottom dead center without opening and closing the valve exactly at the top dead center or the bottom dead center. That is, the intake valve of the engine opens before top dead center and closes after bottom dead center, while the exhaust valve opens before bottom dead center and closes after top dead center. This is to effectively use the inertia of the gas flow because the air or the mixer which is sucked in and discharged into the combustion chamber has inertia. Therefore, in recent years, the application of the continuous variable valve timing apparatus which can change valve timing suitably according to the change of the phase angle of a crankshaft is expanded.

The variable valve timing apparatus of the engine according to the conventional embodiment illustrates a helical spline form and a vane form, as shown in FIGS. 1 and 2. Among these, the use of vane type is increasing.

In Fig. 1, in the conventional variable valve timing apparatus in the form of a helical spline, a pulley 3 is coupled to one side of a cam shaft 2 on which cams 2a of the same number as the number of valves 1 of the engine are arranged. The pulley 3 is connected to the pulley 6a of the oil pump 6 by the timing belt 7. Here, the inner and outer helical splines 4 and 5 having teeth in opposite directions are coupled to the pulley 3 of the camshaft 2. The inner spline 4 is fixed to the camshaft 2 by fitting an internal gear (not shown), and the outer spline 5 is fixed to the pulley 3 by fitting an external gear 5a. Although not shown between the inner gear and the outer gear 5a, a hydraulic chamber is provided before and after the operating piston and the hydraulic pressure of the hydraulic chamber is applied to the camshaft 2 as the operating piston moves forward and backward. The valve timing is varied as the relative phase of the fitted internal gears changes.

In FIG. 2, in the conventional variable valve timing device having a vane shape, a pulley 12 in which the rotation angle of the crankshaft 16 is dominated is coupled to one side of the camshaft 11. The outer housing 12a of the camshaft pulley 12 is used as a housing of an actuator, which is an operating means of a variable device, and a drive gear 13 is fixedly coupled to the outer housing 12a. On the other hand, inside the pulley housing 12a, three to four vanes 14 are provided in the circumferential direction, and the vanes 14 are fixed to the camshaft 11. In this case, each of the sealing members 15 is coupled to the vanes 14. Between the housing 12a and the vane 14, an advance hydraulic chamber and a tectonic hydraulic chamber (not shown) are provided. The variable valve timing device is a variable structure in which the phase of the vanes 14 is changed by adjusting the oil flow rates to the advance hydraulic chamber and the late hydraulic chamber, not shown, so that the phase of the cam shaft 11 connected to the vanes 14 is changed. Is taking.

However, the structure of the helical spline type uses expensive helical gears, which contributes to the cost increase, and the torque required to drive the internal and external splines 4 and 5 becomes too high, thereby increasing the friction loss. have.

In addition, the vane structure is usually used three to four vanes 14, for example, when using three vanes 14, each of the advance and the crust hydraulic chamber is required six, each four In this case, since eight hydraulic chambers are required, not only the structure is complicated, but there is a problem that too many sealing members 15 are required for each airtight chamber.

Therefore, the present invention was created to solve the above-described problems, and an object of the present invention is to change the timing of the valve in a simple structure by changing the phase of the camshaft by rotating the housing in the circumferential direction as the piston moves from side to side. It is to provide a variable valve timing device of the engine.

1 and 2 are a perspective view showing a variable valve timing apparatus of an engine according to a conventional embodiment, Figure 1 is a helical spline form, Figure 2 is a vane form.

3 is a perspective view showing a variable valve timing apparatus of an engine according to an embodiment of the present invention.

4 is an enlarged cross-sectional view of the main portion of FIG. 3;

(A) (b) (c) is an operating state diagram of a variable valve timing apparatus of an engine according to an embodiment of the present invention, where (a) is an advance, (b) is neutral, and (c) is a perception.

※ Explanation of codes for main parts of drawing

10, 20: camshaft 12, 22: camshaft sprocket

30: timing chain 42: intake valve

44 exhaust valve 60 operating means

61 housing 62 cylinder

63: oil passage 64: shell chamber

65: crust chamber 66: piston

67: connecting pin 68: sealing member

In the variable valve timing apparatus of an engine according to the present invention for achieving the above object, in the variable valve timing apparatus of an engine having an operating means coupled to adjust a variable timing of a valve on a sprocket of a camshaft, said operating means Is a housing integrally coupled to a camshaft sprocket, a cylinder having a chamber and a crust chamber rotatably connected in the same phase as the camshaft in the housing, and in communication with an oil passage; And a connecting pin which is hinged to rotate the housing at a predetermined angle according to the movement of the piston between the piston and the housing.

Both ends of the piston are preferably interposed with a sealing member that can prevent the mixing of the oil in the shell chamber and the shell chamber.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

3 is a perspective view illustrating a variable valve timing apparatus of an engine according to an exemplary embodiment of the present invention, and FIG. 4 is an enlarged cross-sectional view illustrating main parts of FIG. 3.

In this figure, the sprockets 12 and 22 are coupled to one side of the intake and exhaust valve side camshafts 10 and 20, and the timing chain 30 is wound between each sprocket 12 and 22. As shown in FIG. On the camshaft 10, 20, the cams 14, 24 have different phases and are in contact with the upper ends of the intake and exhaust valves 42, 44. The camshaft position sensor 50 for checking the rotational angle of the camshaft is mounted around the camshaft 10, 20.

Reference numeral 60 denotes an operation means, which is an actuator coupled to the camshaft sprocket 22 on the exhaust valve 44 side to adjust the variable timing of the intake and exhaust valves 42 and 44.

That is, looking at the detailed configuration of the operating means 60, the housing 61 is integrally coupled on the camshaft sprocket 22, the cylinder 62 is the same as the camshaft 20 in the housing 61; It is connected integrally rotatably in phase. Inside the cylinder 62 is provided a shell chamber 64 and a crust chamber 65 in communication with the oil passage (63) receiving oil from an oil pump (not shown). A piston 66 is positioned at the inner center of the cylinder 62, and the piston 66 reciprocates left and right toward the advance chamber 64 or the perception chamber 65. A connecting pin 67 is hinged between the piston 66 and the housing 61 so as to rotate the housing 61 at a predetermined angle (true, perceptual) as the piston 66 moves. An oil control valve (OCV) 70 is provided near the oil passage 63 to control the oil supply of the advance chamber 64 and the perception chamber 65 by the ECU 80.

Furthermore, when the sealing member 68 such as an O-ring is inserted at both ends of the piston 66, oil mixing between the shell chamber 64 and the crust chamber 65 is prevented in the cylinder 62. It is preferable to prevent it.

The operation of the variable valve timing apparatus of the engine according to the exemplary embodiment of the present invention provided as described above will be described with reference to FIGS. 5 (a) (b) (c).

When the engine is driven, the camshaft position sensor 50 detects the phase of the rotation angle of the camshaft 10 and 20 and sends it to the ECU 80. The ECU 80 analyzes the integrated information with various information of other sensors. After the command to control the oil amount through the oil control valve (OCV) 70 to maintain the proper valve opening and closing angle.

First, when it is necessary to maintain the true angle as shown in Figure 5 (a), when the oil is supplied to the true chamber 64 of the cylinder 62 through the oil passage 63, the piston 66 is perceived by the oil pressure It is horizontally moved toward the chamber 65. At this time, the housing 61 hinged by the piston 66 and the connecting pin 67 is rotated in the clockwise direction. Therefore, the intake and exhaust valves are adjusted to advance the valve timing so that they can be opened before the top dead center.

5 (b) is neutral, so the oil pressures of the chamber chamber 64 and the shell chamber 65 are in balance with each other, so that the piston 66 is positioned in the middle of both chambers 64 and 65. At this time, since the housing 61 does not move, the valve timing coincides.

When the crust is to be maintained as shown in FIG. 5C, when oil is supplied toward the crust chamber 65 of the cylinder 62, the piston 66 is horizontally moved toward the advance chamber 64 by oil pressure. At this time, the housing 61 hinged by the piston 66 and the connecting pin 67 is rotated in the counterclockwise direction. Therefore, the intake and exhaust valves are adjusted so that the valve timing is delayed to open after the top dead center.

According to the present invention described above, since the shape of the component is simple and the friction element is smaller than the conventional one, there is an advantage that the required driving hydraulic pressure is small. In addition, the cost can be reduced by requiring only two sealing members required up to eight in the form of vanes.

Claims (2)

In a variable valve timing apparatus of an engine having an actuating means coupled to adjust a variable timing of a valve on a sprocket of a camshaft, The actuating means includes a housing integrally coupled to the camshaft sprocket, A cylinder which is rotatably connected in the same phase as the camshaft in the housing, and has a chamber and a chamber for communicating with an oil passage; A piston positioned at an inner center of the cylinder and reciprocating left and right toward the advance chamber and the perception chamber, And a connecting pin hingedly coupled to rotate the housing at a predetermined angle according to the movement of the piston between the piston and the housing. The method of claim 1, The variable valve timing apparatus of the engine, characterized in that the sealing member which is inserted in both ends of the piston to prevent the mixing of oil in the chamber and the perception chamber is inserted.