KR20080055396A - Variable valve lift system - Google Patents

Abstract

A variable valve lift apparatus is provided to simplify structure of the valve lift apparatus such that the valve lift apparatus is easily manufactured and the mounting cost thereof is reduced. A variable valve lift apparatus comprises a valve lift adjusting device(30) installed between a cam(10) and a valve(20) to diversely adjust valve lifts. The valve lift adjusting device includes a valve lift adjusting block(31) having a triangle shape and a hydraulic position adjusting device to adjust horizontal positions of the valve lift adjusting block. The valve lift adjusting block allows a cam to make contact with an inclined surface having a triangle shape between the cam and the valve and varies the valve lift while cam contacting position being adjusted at the inclined surface according to the horizontal position of the valve lift adjusting block.

Description

Variable valve lift system

1 is a view showing the structure of a switchable bucket type tappet according to the prior art;

2 is a view showing a high lift and a low lift state in the structure of a switchable bucket type tappet according to the prior art;

3 is a view showing a valve profile in the structure of a switchable bucket type tappet according to the prior art;

4 is a block diagram showing a CVVL system according to the prior art,

5 shows the minimum valve lift state (left) and the maximum valve lift state (right) of the CVVL system shown in FIG. 4;

Figure 6 is an installation state of the valve lift control block in the variable valve lift apparatus of the present invention,

7 is a view illustrating a valve lift adjustment state according to the operating state of the valve lift adjustment mechanism in the variable valve lift apparatus of the present invention;

8 is an exploded perspective view of a valve lift adjusting mechanism including a valve lift adjusting block in the variable valve lift apparatus of the present invention;

9 is an assembled perspective view of the valve lift adjustment mechanism shown in FIG. 8;

10 is a view for explaining the principle of movement of the valve lift control block by the hydraulic pressure in the present invention.

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

10 cam 20 valve

30: valve lift adjusting mechanism 31: valve lift adjusting block

32: piston 33: hydraulic positioning mechanism

34 cylinder 35 cover

36: piston hole 37, 38: doorway

The present invention relates to a variable valve lift apparatus, and more particularly, having a triangular shape, the cam lift valve is positioned between the cam and the valve so as to contact the inclined surface of the triangular shape. The present invention relates to a variable valve lift apparatus having a valve lift adjustment mechanism capable of controlling the valve lift in various ways.

In general, the engine, in the combustion chamber formed between the cylinder and the cylinder head, and the piston reciprocating in the cylinder, transmits the explosive force generated by burning the fuel through the connecting rod connected to the piston to rotate the crankshaft, thereby It is a device that converts mechanical energy.

As described above, the cylinder head of the engine is provided with a combustion chamber in which fuel is combusted to generate power, and the combustion chamber is equipped with an intake valve for providing a mixer containing fuel to be combusted and an exhaust valve for discharging the combusted gas. As such, these intake valves and exhaust valves are configured to open and close the combustion chamber by a valve opening and closing mechanism connected to the crankshaft.

The valve opening and closing mechanism converts the rotational movement of the camshaft into the linear movement of the valve. In general, the opening and closing timing or lift of each valve varies according to the change in the curve of the cam profile surface, thereby affecting the performance of the engine.

Since the number of revolutions typically varies from about 500 RPM to 6000 RPM in an automobile engine, the flow of air or mixer that is sucked into the engine is greatly changed, and the flow rate of air or mixer and exhaust gas is controlled by opening and closing the intake valve and exhaust valve. .

In order to obtain high output at high speed in the engine, it is necessary to increase the charging efficiency by lengthening the open time of the intake valve, but when the open time of the intake valve is increased, the overlap with the exhaust valve becomes large, which is a low speed operation. Since the rotational state of the engine becomes poor at the time, the overlap must be kept within a certain range.

Normal opening and closing of the valve by the valve opening and closing mechanism is made by the cam formed on the cam shaft pushes the end of the valve, the cam shaft is rotated by receiving the driving force of the crankshaft through the timing belt or chain, etc. The contact surface is arcuate in order to reduce friction or wear with the valve.

In this case, the intake valve and the exhaust valve of the engine are opened and closed by the cam, the timing of opening and closing the valve and the amount of opening are determined by the shape of the cam, and the camshaft is driven by the crankshaft, The section in which the valve is opened and closed at a certain point in time and the valve is opened is also made constant based on the crank angle.

That is, the valve is opened and closed at a predetermined time based on the crank angle, which has a fixed value for each engine and has a constant value regardless of the engine speed and the load.

However, since the time the valve is open (actual time, not the crank angle) decreases in inverse proportion to the engine speed, it is difficult to smoothly supply air into the cylinder due to the inertia effect of the air at high speed.

In particular, the conventional valve opening and closing mechanism is a valve having a constant profile, the valve is opened and closed while always forming a constant lift, the valve lift is the maximum height of the cam and the camshaft center, rocker shaft center, the distance between the valve guide The height of the cam and the distance between the parts are fixed, so that the valve lift has a certain characteristic.

According to the valve opening and closing mechanism as described above, since the opening / closing time of the intake / exhaust valve is always fixed at a constant state, it is not possible to control the amount of intake or exhaust air, and thus, There is a problem that does not implement the optimal state.

For example, when the intake / exhaust valve is set on the basis of the high speed operating region, there is a problem that the engine does not exhibit optimal performance in the low speed operating region.

In order to overcome this problem, the industry is actively applying variable valve lift devices, such as Honda's VTEC, Toyota's VVTL-i, Mitsubishi's MIVEC, BMW's Valvetronics and Porsche's Vario system ( Vario System).

The Honda, Toyota, and Mitsubishi systems make the cam in double structure and apply different cam profiles at high speed and low speed while switching between these two cams using hydraulic mechanisms. The system consists of a high speed cam and switches between the low speed cam and the high speed cam by using a dual tappet. BMW's Valvetronics is a device that can continuously change the valve lift and the valve opening section. It consists of a cam.

1 illustrates a structure of a switchable bucket type tappet (used by Porsche and Subaru) according to the prior art, and FIG. 2 illustrates a high lift and low lift state in the structure of a switchable bucket type tappet. 3 is a view showing the valve profile in the structure of the switchable bucket type tappet.

In such a switchable bucket type tappet structure, the oil can be injected into the oil hole 1 to move the pin 2 to select the tappet, and the cam profile is changed according to the tappet selection.

However, the problem with this mechanism is that it can only adjust the valve lift in two steps as shown in Fig. 3, and the mechanism is simple but has the disadvantage of not having various valve lifts.

Figure 4 is a block diagram showing a CVVL (Continuous Variable Valve Lift) system according to the prior art, Figure 5 shows the minimum valve lift state (left) and the maximum valve lift state (right) of the CVVL system shown in FIG. Drawing.

Since the conventional valve opening and closing mechanism (valvetronics) cannot change the valve lift, fuel economy and output cannot be optimized, and a variable valve lift device as shown in FIG. 4 has been developed, which is the first representative CVVL system. .

However, in the CVVL system as shown, there is a disadvantage that the middle lever 3 is relatively large and there is a separation point on the side of the inertia mass, and the eccentric shaft 4 is higher and the height is higher than the cam 5.

In addition, since the intermediate lever 3 is a structure floating between the eccentric shaft 4 and the swing arm 6, there is a possibility of malfunction.

Accordingly, the present invention has been invented to solve the above problems, it is possible to change a variety of valve lift compared to the conventional switchable bucket type tappet, it is possible to operate stably while mounting height is higher than the valvetronic structure The purpose of the present invention is to provide a variable valve lift device having a reduced advantage and having a relatively simple structure, which is easy to manufacture as compared to a conventional variable valve lift device and can reduce installation costs.

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

In order to achieve the above object, the present invention, in the variable valve lift apparatus of a vehicle engine,

Installed between the cam and the valve is provided with a valve lift adjustment mechanism for controlling the valve lift in a variety of ways,

The valve lift adjustment mechanism,

A valve lift adjusting block having a triangular shape so that the cam is in contact with the triangular inclined surface between the cam and the valve, and the valve lift control block changing the valve lift while the cam contact position on the inclined surface is adjusted according to the front and rear positions;

A hydraulic position adjusting mechanism for adjusting the front and rear positions of the valve lift adjusting block;

It provides a variable valve lift apparatus comprising a.

Here, the hydraulic position adjustment mechanism,

Assembled on both sides of the valve lift control block, so that the hydraulic pressure is applied to the front and rear surfaces of the piston inserted therein, while the pistons integrally formed on both sides of the valve lift control block are respectively inserted into the inner space. It characterized in that it comprises a cylinder for controlling the front and rear positions of the entire valve lift control block via the piston.

In addition, the cylinder, characterized in that the front and rear ends, based on the piston inserted therein, the oil inlet through which the oil of the hydraulic mechanism is supplied and discharged is formed.

In addition, the hydraulic position adjustment mechanism,

It is interposed between the inner surface of each cylinder and each side of the valve lift control block, further comprising a cylinder cover formed with a piston hole so that the piston of the valve lift control block inserted into the cylinder while sealing the inner surface of the cylinder; It is characterized by.

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

The present invention relates to a variable valve lift apparatus configured to obtain a CVVL (Continuous Variable Valve Lift) effect by using a concept of a switchable bucket type tappet. As shown in FIG. The valve lift control block 31 is positioned between the cam 10 and the valve 20 in a triangle-shaped valve lift control block 31 and the cam 10 is in contact with the upper inclined surface of the valve lift control block 31. By moving the position of the 31 back and forth by the hydraulic pressure is configured to be able to variously adjust the lift of the valve (20).

In Fig. 6, reference numeral 21 denotes a valve spring.

7 is a view illustrating a valve lift adjustment state according to the operation state of the valve lift adjustment mechanism in the variable valve lift apparatus of the present invention, (a) is a state in which the valve is closed, and (b) is a minimum valve lift. The state, (c) shows the intermediate valve lift state, and (d) shows the maximum valve lift state.

As shown in the drawing, the valve lift adjustment mechanism 30 of the present invention is provided in a triangular shape so that the cam 10 is in contact with the inclined surface of the upper side, and the valve can be moved back and forth (left and right in the figure) by hydraulic pressure. Lift control block 31 is included.

7 shows that the valve lift may be variously changed as the front and rear positions of the valve lift adjusting block 31 to which the cam 10 is in contact with the bar 10 may move the valve lift adjusting block 31. This is similar to the principle of operating a hydraulic CVVT.

Attached FIG. 8 is an exploded perspective view of a valve lift adjustment mechanism including a valve lift control block in the variable valve lift apparatus of the present invention, FIG. 9 is an assembled perspective view of the valve lift adjustment mechanism shown in FIG. 8, and FIG. 10. Is a view for explaining the operating state of the valve lift control block by hydraulic pressure.

As shown, the valve lift adjustment mechanism 30 used in the variable valve lift apparatus of the present invention is provided in a triangular shape as described above, the valve lift adjustment block is in contact with the surface of the upper cam 10 to the inclined surface And a hydraulic position adjusting mechanism 33 for moving and controlling the front and rear positions of the valve lift adjusting block 31.

The hydraulic position adjusting mechanism 33 is assembled on both sides of the valve lift control block 31 and the piston 32 integrally formed on both sides of the valve lift control block 31 is inserted into the internal space, respectively. By acting hydraulic pressure on the front and rear surfaces of the piston 32 inserted in the inside is configured to control the position of the valve lift control block 31 via the piston (32).

The hydraulic position adjusting mechanism 33 is assembled to both sides of the valve lift control block 31, respectively, the cylinders 34 to which the pistons 32 of the valve lift control block 31 are inserted, and each of the cylinders. The piston hole 36 is interposed between the inner surface of the valve lift control block 31 and each side of the valve lift control block 31 to seal the inner surface of the cylinder 34 so that the piston 32 of the valve lift control block 31 penetrates. The cylinder cover 35 in which () is formed is made into a basic structure.

Here, the cylinder cover 35 is interposed to prevent the leakage of oil, it is possible to reinforce the oil sealing by making a stage between the cylinder cover 35 and the inner surface of the cylinder 34.

The piston 32 of the valve lift control block 31 is supplied through selected oil inlets 37 and 38 respectively formed at the front and rear ends of each cylinder 34 in a state of being inserted into the cylinder 34. The oil is under pressure.

That is, the piston 32 is pressurized and moved by the hydraulic pressure of the oil supply side while the oil is supplied to one of the two oil entrances 37 and 38 formed at the front and rear ends and the oil is discharged to the opposite side. When the valve 32 is moved by hydraulic pressure, the entire valve lift control block 31 is moved back and forth together with the cylinder cover 35, and thus the oil supply and discharge into the cylinder 34 are controlled and the cylinder 34 is moved. As the front and rear positions of the piston 32 in the) is controlled, the front and rear positions of the valve lift control block 31 are controlled.

As shown in FIG. 7, when the front and rear positions of the valve lift adjusting block 31 are continuously controlled, the valve lift may be continuously controlled while the cam 10 contact position of the inclined surface is changed.

The control of oil supplied to the cylinder 34 before and after the piston 32, that is, the control of oil supply and discharge through the front and rear entrances 37 and 38 of the cylinder 34, is performed by the front and rear entrances 37 and 38. This is possible by means of a conventional hydraulic system which can selectively supply oil through), which is the same principle as operating hydraulic CVVT.

In this way, the variable valve lift apparatus according to the present invention is provided in a triangular shape and the valve lift adjusting block 31 and the valve lift so that the cam 10 is in contact with the upper inclined surface, the valve lift can be adjusted By providing a valve lift adjustment mechanism 30 including a hydraulic position adjustment mechanism 33 for moving the control block 31, by using the hydraulic position adjustment mechanism 33 to control the position of the valve lift adjustment block 31 Various valve lifts can be adjusted.

As described above, the variable valve lift apparatus according to the present invention has a triangular shape between the cam and the valve so that the cam is in contact with the inclined surface of the triangular shape, the position of the valve lift control block installed by the hydraulic position adjustment mechanism It is provided with a valve lift adjustment mechanism that can control the valve lift by a variety of control, according to the variable valve lift apparatus of the present invention, various changes in the valve lift is possible compared to the conventional switchable bucket type tappet, Compared with the valvetronics structure, the mounting height is reduced, and since the structure is relatively simple, it is easy to manufacture compared to the existing variable valve lift device and has an advantage of reducing the mounting cost.

Claims (4)

In the variable valve lift apparatus of a vehicle engine, Installed between the cam and the valve is provided with a valve lift adjustment mechanism for controlling the valve lift in a variety of ways, The valve lift adjustment mechanism, A valve lift adjusting block having a triangular shape so that the cam is in contact with the triangular inclined surface between the cam and the valve, and the valve lift control block changing the valve lift while the cam contact position on the inclined surface is adjusted according to the front and rear positions; A hydraulic position adjusting mechanism for adjusting the front and rear positions of the valve lift adjusting block; Variable valve lift apparatus comprising a. The method according to claim 1, The hydraulic position adjustment mechanism, Assembled on both sides of the valve lift control block, so that the hydraulic pressure is applied to the front and rear surfaces of the piston inserted therein, while the pistons integrally formed on both sides of the valve lift control block are respectively inserted into the inner space. Variable valve lift device characterized in that it comprises a cylinder for controlling the front and rear positions of the entire valve lift control block via the piston. The method according to claim 2, The cylinder is a variable valve lift apparatus, characterized in that the front and rear ends of the cylinder is inserted into the oil outlet for supplying and discharging the oil of the hydraulic mechanism is formed. The method according to claim 2, The hydraulic position adjustment mechanism, It is interposed between the inner surface of each cylinder and each side of the valve lift control block, further comprising a cylinder cover formed with a piston hole so that the piston of the valve lift control block inserted into the cylinder while sealing the inner surface of the cylinder; Variable valve lift apparatus, characterized in that.

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