KR20070009094A - Variable valve lift system for engine - Google Patents

Abstract

A variable valve lift system for an engine is provided to prevent damage of a cam knob or a tappet by preventing striking noise generated between metals. A variable valve lift system for an engine, comprises a cam(12), a tappet housing(13), a lost motion shaft(14), a shaft locking pin(15), a return spring(16), a connecting rod(17), and a lost motion spring(18). The cam rotates by power of an engine so as to open/close a valve(11) in accordance with combustion timing. The tappet housing directly contacts the cam so as to receive pressure force of the cam, and has a chamber(C) for storing components, and an oil supply hole(13a) for introduction of oil into the chamber from the engine. The lost motion shaft is arranged beneath the tappet housing so that the lost motion shaft moves in a vertical direction within the chamber. The lost motion shaft serves as a rotor for direct contact between the valve and a tappet during lost motion. The shaft locking pin is arranged on the lost motion shaft in the chamber so as to prevent rotation of the lost motion shaft. The return spring is interposed between the lost motion shaft and the shaft locking pin so as to return the shaft locking pin to its original position. The connecting rod is arranged beneath the lost motion shaft so as to allow for continuous contact between the lost motion shaft and the valve. The lost motion spring is arranged on a center of the lost motion shaft so that force is constantly applied to a lower portion of the lost motion shaft.

Description

VARIABLE VALVE LIFT SYSTEM FOR ENGINE

1 is a view schematically showing the configuration of a variable valve lift apparatus of an engine according to the present invention.

Figure 2 is a schematic diagram showing sequentially the operation when the variable valve lift apparatus of the engine according to the present invention is a low lift.

Figure 3 is a schematic diagram showing sequentially the operation when the variable valve lift apparatus of the engine according to the present invention is a high lift.

<Description of the symbols for the main parts of the drawings>

11.Intake valve

12. Cam

13. Tappet Housing

13b. Home

14. Shaft for Lost Motion

14a. Pin groove

15. Shaft Locking Pin

16. Return Spring

17. Conload

18. Spring for Lost Motion

19. Shaft Bearing

21. Cylinder head

21a. Oil supply

The present invention relates to a variable valve lift apparatus of an engine, and more particularly, to a variable valve lift apparatus of an engine improved to have a function of maintaining a direct contact between a tappet and a valve at all times while having a spring for lost motion. It is about.

Many variable valve lift systems (VVLs) have been proposed to realize excellent fuel efficiency in low speed and low load sections. For example, Korean Patent Laid-Open Publication No. 2005-0010438 (January 27, 2005) and 2005-0010437 (January 27, 2005) disclose a variable valve lift apparatus for an engine speed sensitive vehicle, respectively.

However, the proposed techniques are always in high lift, so the tip of the cam knob is almost in contact with the tappet, which works the same as in the current engine.

In the case of low lift, as the cam rotates while the upper end of the cam knob and the tappet are separated by a predetermined distance, the tip of the cam knob presses the tappet to implement low lift.

However, the biggest problem in the prior art can arise when operated with low lift. In the case of the high lift, the knob of the cam and the top of the tappet remain almost in contact with each other so that the cam can operate without any sound when the tappet is pressed downwards.

However, in the case of the low lift, the upper end of the tappet is kept away from the cam by a certain distance, and the valve is pressed when the knob of the cam approaches and hits the tappet. have.

This phenomenon is that the faster the engine speed, the greater the strength of the hit, and the greater the impact force, thereby damaging the knob of the cam or the top of the tappet and eventually damaging the entire engine.

The present invention was created in order to solve the above problems, provided with a spring for the lost motion to maintain a direct contact between the tappet and the valve at all times to provide a variable valve lift apparatus of the engine to prevent the occurrence of sounding. There is this.

Variable valve lift apparatus of the engine of the present invention for achieving the above object, the cam is rotated by receiving the engine power to open and close the valve in accordance with the combustion timing; A tappet housing in which an oil supply hole is formed at one side thereof so as to directly contact the cam so as to receive a pressing force by the cam, and an empty space for forming other mechanisms therein; ; A shaft for lost motion installed on one side of the bottom of the tappet housing to move up and down within the chamber, and for a direct contact between the valve and the tappet during lost motion; A shaft locking pin installed at an upper portion of the shaft for the lost motion in the chamber and entering to prevent rotation of the shaft for the lost motion; A return spring disposed between the shaft for the lost motion and the shaft locking pin to return the shaft locking pin to its original position; A conrod mounted to the bottom of the shaft for lost motion for continuous contact between the shaft for the lost motion and the valve; Roast motion spring is installed on the center upper portion of the shaft for the lost motion so that the force is always applied downward to the shaft for the lost motion; characterized in that it comprises a.

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

1 is a block diagram schematically showing the configuration of a variable valve lift apparatus of an engine according to the present invention.

Referring to the drawings, the variable valve lift apparatus of the engine according to the present invention includes, for example, a cam 12 which is rotated by receiving engine power to open and close the intake valve 11 according to the combustion timing, and the cam 12. A chamber C is formed to be in contact with the cam 12 so as to directly receive a pressing force, and an empty space is formed therein so that other mechanisms described later are embedded therein and oil from the oil supply portion 21a formed in the cylinder head 21 of the engine. An oil supply hole 13a is installed at one side thereof and an oil supply hole 13a is installed at one side of the bottom part of the tappet housing 13 so as to flow into the chamber C. The oil supply hole 13a is operated to elevate the inside of the chamber C. Lost motion shaft 14, a rotor for direct contact between valve 11 and tappet during lost motion, and lost motion shaft 14 in chamber C of tappet housing 13. Of the shaft for lost motion 14 And a shaft locking pin 15 which is entered to prevent rotation.

In addition, the variable valve lift apparatus of the engine according to the present invention includes a return spring provided between the shaft 14 for lost motion and the shaft locking pin 15 to return the shaft locking pin 15 to its original position. 16, the con rod 17 provided at the bottom of the lost motion shaft 14 for continuous contact between the lost motion shaft 14 and the valve 11, and the lost motion shaft 14 Lost motion springs 18 are provided at the upper center so that the force for the lost motion shaft 14 is always applied downward.

In addition, the oil supply hole 13a is formed on the upper sidewall of the tappet housing 13 so as not to rotate the shaft 14 for the lost motion during the high lift.

In addition, a shaft bearing seating groove 13b is formed in one sidewall of the tappet housing 13 so that the shaft bearing 19 installed at both ends of the shaft 14 for lost motion is seated. In addition, a pin groove 14a is formed on the upper surface of the shaft 14 for the lost motion so that the shaft locking pin 15 is inserted during the lifting operation of the shaft 14 for the lost motion.

And the upper surface of the inside of the tappet housing 13 is formed with a receiving groove (13c) for accommodating the lost motion spring (18) when compressing the lost motion spring (18). In addition, in order to limit the operation of the shaft locking pin 15, an internal operating part 13e formed of at least one protrusion 13d is formed inside the tappet housing 13.

Meanwhile, reference numeral 22 not illustrated in FIG. 1 represents a snap ring.

Referring to the operation of the variable valve lift apparatus of the engine according to the present invention having the configuration as described above are as follows.

As described above, in order to solve the sounding caused by the metal-to-metal collision, which is a problem of the prior art, the structure of the inside of the tappet housing 13 should be provided with a lost motion spring 18, and the lost motion spring 18 The tappet housing 13 and the valve 11 should operate while maintaining direct contact when the c) is operated.

Therefore, in the variable valve lift apparatus of the engine according to the present invention, the tappet housing 13 and the valve 11 have a function of always maintaining direct contact with the spring 18 for the lost motion based on this concept. It was.

As shown in FIG. 2, the tappet housing 13 is in direct contact with the cam 12 and other instruments are installed. The oil supply hole 13a formed therein does not rotate the shaft 14 for the lost motion during high lift. It is an entrance and exit of oil supplied from the oil supply portion 21a of the cylinder head 21 of the engine in order to prevent it.

In addition, the seating groove 13b on which the shaft bearing is seated is formed such that the shaft bearings 19 installed at both ends of the shaft 14 for the lost motion for the lost motion are seated, and the shaft locking pin 15 is the lost motion. It is used to enter to prevent rotation of the dragon shaft 14.

In addition, the return spring 16 is for returning the shaft locking pin 15 to its original position. The shaft 14 for the lost motion is used for direct contact between the valve 11 and the tappet during the lost motion. Overall, the conrod 17 is a component for continuous contact of the shaft 14 for the lost motion with the valve 11. And the lost motion spring 18 is used to force the lost motion shaft 14 downwards at all times.

This will be described in more detail.

First, FIGS. 2 and 3 are respectively shown an operation diagram showing the operating state of the variable valve lift apparatus of the engine according to the present invention.

First, FIG. 2 is an operation diagram for implementing a low lift required at a low speed low load, in which part (a) is when the cam 12 has not yet operated the tappet, and (b) and (c) Continually shows the situation in which the cam 12 presses down on the tappet housing 13. In particular, (b) of FIG. 2 shows the last moment of the lost motion when the cam 12 presses down on the tappet housing 13. When the tappet housing 13 is pressed down, the valve 11 is completely Only the relative distance between the tappet housing 13 and the lost motion shaft 14 is completely reduced without opening.

In FIG. 2C, when the tappet housing 13 is further rotated, the lost motion of the lost motion shaft 14 in the tappet housing 13 is completed so that the tappet and the valve 11 are one rigid. Like the body (Rigid Body) is pressed down to show a slight opening of the valve 11 is implemented.

In this way, during the low lift, the tappet and the valve 11 continue to contact each other by the rotation of the lost motion shaft 14 corresponding to the lost motion, so that no metal-to-metal friction noise occurs.

3 is an operation diagram during high lift, and FIGS. 3A, 3B, and 3C show continuous operation of the cam 12, the tappet and the valve 11 during the high lift. . As shown in (a) of FIG. 3, when the cam 12 has not yet pressed the tappet housing 13, when a command of a high lift is transmitted from the ECU, a high pressure is supplied through the oil supply hole 13a. The engine oil is supplied, and this high-pressure engine oil lowers the shaft locking pin 15 to fix the shaft 14 for the lost motion so that the shaft 14 for the lost motion cannot be rotated.

3 (b) shows when the cam 12 is further rotated to lower the tappet housing 13 further downward. The shaft 14 for the lost motion is prevented by the shaft locking pin 15. Since it is already fixed, the tappet, the shaft for the lost motion 14, and the valve 11 become one rigid body, and the valve 11 is opened to a large extent. This can be compared with (b) of FIG. 2 described above.

3 (c) of FIG. 3 shows a state in which the cam 12 is rotated by 90 degrees and the tappet is completely lowered. At this time, the lift of the valve 11 is maximized.

On the other hand, in Figs. 2 and 3, dotted lines at regular intervals are shown in the background to numerically view the amount of lift of the valve 11 at the time of low and high lift, respectively.

As described above, the variable valve lift apparatus of the engine according to the present invention has the following effects.

Although the cam is rotated by the non-contact amount of a considerable distance between the cam at the time of low lift and the upper end of the tappet housing, which is the biggest disadvantage of the prior art, the impact sound occurs when the cam is in contact with the tappet housing. The main structure of the shaft and the conduit for lost motion, which allows continuous tappet and valve contact, can be completely solved while maintaining the function of the variable valve lift device of the general engine. have.

Therefore, the occurrence of sounding due to the collision of metal and metal is prevented, so that damage to the cam knob or tappet does not occur, thereby improving the performance of the engine.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent embodiments are possible. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

Claims (6)

A cam rotated by receiving engine power to open and close the valve according to the combustion timing; A tappet housing in which an oil supply hole is formed at one side thereof so as to directly contact the cam so as to receive a pressing force by the cam, and an empty space for forming other mechanisms therein; ; A shaft for lost motion installed on one side of the bottom of the tappet housing to move up and down within the chamber, and for a direct contact between the valve and the tappet during lost motion; A shaft locking pin installed at an upper portion of the shaft for the lost motion in the chamber and entering to prevent rotation of the shaft for the lost motion; A return spring disposed between the shaft for the lost motion and the shaft locking pin to return the shaft locking pin to its original position; A conrod mounted to the bottom of the shaft for lost motion for continuous contact between the shaft for the lost motion and the valve; And a lost motion spring installed at a center upper portion of the shaft for the lost motion such that a force is always applied downward to the shaft for the lost motion. The method of claim 1, The oil supply hole, the variable valve lift apparatus of the engine, characterized in that formed in the upper side wall of the tappet housing to prevent the rotation of the shaft for the lost motion during high lift. The method of claim 1, A variable valve lift apparatus for an engine, characterized in that a seating groove is formed on one sidewall of the tappet housing for mounting a shaft bearing installed at both ends of the shaft for lost motion for lost motion. The method of claim 1, The upper surface of the shaft for the lost motion variable valve lift apparatus of the engine, characterized in that the pin groove for inserting the shaft locking pin is inserted during the lifting operation of the shaft for the lost motion. The method of claim 1, The upper surface of the inside of the tappet housing variable valve lift apparatus of the engine, characterized in that the receiving groove for receiving the spring for the lost motion when the compression for the spring for the lost motion is formed. The method of claim 1, The variable valve lift apparatus of the engine, characterized in that an operating part consisting of at least one protrusion is formed inside the tappet housing to limit the operation of the pin for locking the shaft.

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