KR101911102B1 - Variable valve timing apparatus - Google Patents

Abstract

The present invention relates to a valve timing device capable of adjusting the closing timing of an intake and exhaust valve of an engine. The valve timing device includes an actuator housing having an upper chamber and a lower chamber and a connecting chamber, And a second communication path including a first communication path and an on-off valve for communicating the first communication path and the lower chamber. The first communication path is opened / closed according to an elevating operation in the upper chamber, And a piston that opens and closes the lower end of the second communication passage in accordance with the lifting operation, whereby the oil circulation path can be selectively So that it is possible to adjust the timing at which the intake and exhaust valves are closed.

Description

[0001] The present invention relates to a variable valve timing apparatus,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a variable valve timing device capable of adjusting a closing timing of an intake and exhaust valve of an engine. More specifically, The present invention relates to a variable valve timing device capable of reducing the amount of harmful substances in the exhaust gas such as NOx as well as improving the output and efficiency of the engine.

2. Description of the Related Art In recent years, there has been an increasing demand for environmentally friendly high efficiency engines. Various engine performance improvements have been progressing, and control techniques have been actively developed as well as producing optimum parts for securing high efficiency of engines.

Especially, in order to improve the engine performance, since the optimum intake or exhaust conditions have a great influence, various techniques for optimizing the opening and closing timing of the intake valve or the exhaust valve in the engine through the adjustment of the valve timing, .

As described above, the technique of varying the opening and closing timings of the intake and exhaust valves to optimize the thermal efficiency and the output and improve the fuel economy is the variable valve timing of the engine in accordance with the conditions such as the operation speed and the load of the engine.

As a general technique related to the variable valve timing device, there is a device for changing the phase of the cam to advance the opening timing of the valve to advanced or retarded. In the conventional engine, The cam profile controls the opening and closing of the valve using the combustion drive system.

However, such a variable valve timing device can not change its timing during engine operation unless the cam is changed, and it is also possible to use a helical gear type, a torsional spline type, a vane type, or an electrohydraulic type at the front end portion of the camshaft And the cam phase changing mechanism is required to be provided, which has a problem in that the structure becomes very complicated and the size of the cylinder head portion becomes uneven.

As another example of the variable valve timing device, there is known a device which modifies the structure of the valve lift mechanism to change the open duration and the opening / closing timing of the valve. However, such a device is also structurally complicated and increases the volume of the cylinder head portion There were various problems.

Korean Patent Publication No. 10-2013-0031222 (March 31, 2013)

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide an actuator in which an upper chamber in which a push rod lifter is installed and a lower chamber in which a piston is installed are communicated with each other so that oil can be circulated, By selectively circulating the exhaust gas through the first and second communication paths, it is possible to adjust the closing timing of the intake and exhaust valves according to engine operating conditions, thereby providing a variable valve timing device capable of reducing harmful substances in exhaust gas such as NOx I would like to.

According to an aspect of the present invention, there is provided an actuator comprising: an actuator housing having an upper chamber, a lower chamber, and a connecting chamber connecting the upper chamber and the lower chamber; a first communication path communicating the side surfaces of the upper chamber and the lower chamber with each other; A second communication path connecting the first communication path and the lower side surface of the lower chamber with an on-off valve, and a second communication path provided in the upper chamber so as to be able to move up and down, And a return spring installed on the lower chamber to be able to move up and down on the lower side of the return spring, And a piston that opens and closes the lower end of the two communication paths and discharges the oil in the second communication path.

Wherein the push rod lifting portion is resiliently supported by a push rod lifter that is vertically installed in the upper chamber and opens and closes the first communication path and a spring provided below the push rod lifter, And a check valve for blocking movement to the lower chamber.

The piston further includes a main exhaust passage through which the oil in the lower chamber is discharged downward so as to supply oil to a piston rod connected to the lower side of the piston, and an auxiliary exhaust passage for discharging the oil of the second communication passage downwardly, Respectively.

The auxiliary discharge passage may include a circulation flow path having a predetermined depth formed in an annular shape along an outer circumferential surface of the piston, and a drain hole for discharging the oil introduced into the circulation flow path downward.

Meanwhile, it is preferable that a plurality of the drain holes are provided at equal intervals along the circulating flow path.

The second communication path includes an upper flow path, a lower flow path, and a connection flow path connecting the upper flow path and the lower flow path, and the opening / closing valve is slidably inserted into the connection flow path to block oil movement.

As described above, according to the present invention, it is possible to selectively change the circulation path of the oil to adjust the closing timing of the intake and exhaust valves according to the engine operation conditions, thereby improving the engine efficiency and the output, It is possible to reduce the environmental pollution by reducing the harmful substances such as the exhaust gas, and the degree of freedom in designing can be improved by adjusting the opening and closing timings of the intake and exhaust valves.

1 is a schematic diagram of a general intake and exhaust system equipped with a variable valve timing device of the present invention,
2 is a sectional view of the variable valve timing device of the present invention,
3 is a perspective view of a piston provided in the variable valve timing device of the present invention,
4 is an operational state of the variable valve timing device of the present invention when the intake and exhaust valves are opened;
5 is an operational state of the variable valve timing device of the present invention when the intake and exhaust valves are normally closed;
6 is an operational state diagram of the variable valve timing device of the present invention for advancing the closing timing of the intake and exhaust valves,
7 is a graph showing the valve profile analysis by the variable valve timing device of the present invention.

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

Fig. 1 is a schematic diagram of a general intake and exhaust system equipped with a variable valve timing device of the present invention.

As shown, the variable valve timing device 100 is provided to have a predetermined length and is disposed between the push rod 250 and the swing arm 220.

The swing arm 220 moves up and down in conjunction with the cam shaft 200 to move the piston rod 230 up and down to operate the variable valve timing device 100 of the present invention.

Therefore, the variable valve timing device 100 of the present invention changes the timing at which the push rod 250 is lowered after the push rod 250 is changed in transmitting the operation of the swing arm 220 to the push rod 250, So that the closing time can be changed.

Hereinafter, the variable valve timing device of the present invention will be described in detail with reference to FIGS. 2 and 3. FIG.

Here, FIG. 2 is a sectional view of the variable valve timing device of the present invention, and FIG. 3 is a perspective view of a piston of the variable valve timing device of the present invention.

The variable valve timing device 100 of the present invention includes the actuator housing 10, the first communication path 20, the second communication path 30, the push rod lifting portion 40, the return spring 50, , And a piston (60).

Here, the actuator housing 10 has an outer shape of a predetermined length, and an upper chamber 12, a lower chamber 13, and a connection chamber 15 are provided therein.

At this time, the connection chamber 15 has an inner diameter relatively smaller than that of the upper chamber 12 and the lower chamber 13 to connect the lower end of the upper chamber 12 and the upper end of the lower chamber 13, .

On the other hand, an oil inlet 16 for injecting engine oil is provided on one side of the actuator housing 10.

The oil inlet 16 is connected to the upper chamber 12 and the lower chamber 13 through a first communication path 20 to be described later and is connected to the upper chamber 12 and the lower chamber 13, And a check valve 17 is installed so that only the injection can be performed

Therefore, the upper chamber 12, the lower chamber 13, and the connection chamber 15 are maintained filled with oil.

Also, a push rod 250 (shown in FIG. 1) is inserted into the upper portion of the actuator housing 10 to be slidable in the upward and downward directions.

As shown in FIG. 2, the first communication path 20 may be formed in a 'C' shape so as to communicate the side surfaces of the upper chamber 12 and the lower chamber 13 with each other, And the upper portion is connected to the lower side of the upper chamber 12 and the oil inlet 16 and the lower portion is connected to the upper end side of the lower chamber 13. [

Therefore, the first communication passage 20 forms an oil passage in the other direction besides the connecting chamber 15, so that the upper chamber 12 and the lower chamber 13 communicate with each other in different directions.

On the other hand, the second communication path 30 serves to communicate the first communication path 20 with the lower side surface of the lower chamber 13, and an on-off valve 37 is provided to selectively open and close the first communication path 20 as required .

The second communication path 30 is provided with an upper flow path 31 connected to a lower portion of the first communication path 20 and a lower flow path 33 and a connection flow path 35 connected to the lower chamber 13.

The upper flow path 31 and the lower flow path 33 are vertically installed and the connection flow path 35 is installed horizontally to connect the upper flow path 31 and the lower flow path 33 with each other.

At this time, the on-off valve 37 is provided to open and close the connection passage 35.

As shown in FIG. 2, the on-off valve 37 is slidable horizontally and is provided to open and close the connection passage 35 by inserting the tip end portion into the connection passage 35 in the longitudinal direction.

At this time, the opening / closing valve 37 may be capable of sliding operation using compressed air.

On the other hand, a push rod lifting unit 40 is installed on the upper chamber 12 so as to be able to move up and down.

The push rod lifting section 40 is constituted by a push rod lifter 41, a spring 43 and a check valve 45 for pushing the push rod 250 upward to open the intake and exhaust valve 280 do.

The push rod lifter 41 functions to open and close the upper end of the first communication path 20 connected to the lower side of the upper chamber 12 in accordance with the lifting operation of the push rod lifter 41 .

At this time, as shown in the figure, the push rod lifter 41 is formed with a hemispherical push rod support member 42 at its upper portion, and a groove 47 having a predetermined depth in the form of an annulus is formed on the lower side.

The groove (47) is provided with a spring (43).

The spring 43 elastically supports the check valve 45 from above and presses the check valve 45 downward. The check valve 45 serves to open and close the upper end of the connection chamber 15.

The check valve 45 allows the oil to move only in the direction of the upper chamber 12 from the lower chamber 13. The check valve 45 has a circular shape formed obliquely along the outer circumferential surface so as to pressurize and seal the upper end of the connecting chamber 15. [ A pressing surface 46 is provided.

Thus, the oil can push the check valve 45 upward and move from the lower chamber 13 to the upper chamber 12, but the movement from the upper chamber 12 to the lower chamber 13 becomes impossible.

On the other hand, a return spring 50 and a piston 60 are installed in the lower chamber 13.

The return spring 50 serves to press the piston 60 downward to return the piston 60. The return spring 50 rests on the upper chamber 13 to elastically support the piston 60 from above.

Meanwhile, the piston 60 is mounted on the upper portion of the piston rod 230 connected to the swing arm 220 so as to closely contact the lower side thereof, thereby performing a lifting operation in conjunction with the operation of the swing arm 220.

At this time, the main discharge passage 62 is vertically penetrated through the center of the piston 60, and the piston rod supporting surface 63, which is in close contact with the upper end surface of the piston rod 230,

Here, the main discharge passage 62 is provided so that the oil filled in the lower chamber 13 is also supplied to the piston rod supporting surface 63 to lubricate.

On the other hand, an auxiliary discharge path (68) is provided on the outer peripheral surface of the piston (60).

At this time, the auxiliary discharge path (68) is constituted by the circulation flow path (65) and the drain hole (66).

The circulation flow path 65 is formed horizontally along the outer circumferential surface of the piston 60 and is formed in an annular groove shape having a predetermined depth so that the lower end of the second communication path 30 Lt; / RTI >

Accordingly, the piston 60 opens and closes the lower end of the second communication passage 30 in accordance with the lifting operation.

3, the drain hole 66 is provided to penetrate the circulation flow passage 65 in the vertical direction, and the circulation flow passage 65 (see FIG. 3) It is preferable to arrange a plurality of units at regular intervals.

The piston 60 moves up the push rod lifter 41 by moving the oil filled in the lower chamber 13 by using the movement of the piston rod 230 lifted by the swing arm 220, So that the exhaust valve 280 is opened and closed.

Hereinafter, the operation of the variable valve timing device according to the present invention will be described in detail with reference to FIGS.

FIG. 4 is a diagram showing an operational state of the variable valve timing device of the present invention when the intake and exhaust valves are opened, FIG. 5 is a diagram showing an operational state of the variable valve timing device during normal closing of the intake and exhaust valves, FIG. 7 is a graph showing an analysis of a valve profile by the variable valve timing device of the present invention. FIG. 7 is a graph showing an operating state of the variable valve timing device for advancing the closing timing of the exhaust valve.

First, Fig. 4 shows an operation process for opening the intake and exhaust valves. In this case, the on-off valve 37 keeps the flow path of the second communication path 30 closed.

Accordingly, as shown in FIG. 4, when the piston rod 230 (shown in FIG. 1) is moved upward by the operation of the swing arm 220 to raise the piston 60 as indicated by an arrow, The oil filled in the lower chamber 13 is pushed up and moved upward.

At this time, the oil in the lower chamber 13 presses the check valve 45 upward to move to the upper chamber 12, and then raises the push rod lifter 41 upward, The valve is opened.

5, since the oil in the upper chamber 12 can not move to the connection chamber 15, the piston 60 moves to the top dead center, Is moved to the lower chamber 13 along the one communication path 20, and the push rod lifter 41 also moves downward to correspondingly close the suction and exhaust valves.

Meanwhile, FIG. 6 shows an operation process according to the closing timing adjustment of the intake and exhaust valves according to engine operating conditions.

In the operating state shown in Fig. 6, the open / close valve 37 keeps the second communication path 30 in an opened state, so that the oil can be moved downward also through the second communication path 30. [

4, the piston 60 first rises and pushes up the oil filled in the lower chamber 13, and the oil lifts the push-rod lifter 41 to the intake and exhaust valve 280, .

The piston 60 is lifted and the push rod lifter 41 is raised. At this time, before the piston 60 reaches the top dead center, the second communication passage 30 is connected to the auxiliary discharge passage The oil in the upper chamber 12 sequentially flows through the first communication path 20 and the second communication path 30 as indicated by the arrow 350 and flows into the drain hole 66, respectively.

The push rod lifter 41 is in a state in which the piston 60 is lifted before the piston 60 reaches the top dead center because the oil in the upper chamber 12 first begins to be discharged through the second communication passage 30, The suction and exhaust valve 280 is closed earlier than normal by moving downward before reaching the top dead center.

Therefore, in the normal operation as shown in FIGS. 4 and 5, the piston 60 and the push rod lifter 41 start to rise at the same time and then descend simultaneously at the top dead center. In the variable valve timing operation The push rod lifter 41 is lowered faster than the piston 60, so that the closing timing of the intake / exhaust valve 280 is advanced earlier than normal.

Accordingly, the variable valve timing device 100 of the present invention can adjust the closing timing of the intake and exhaust valve 280, and it is possible to improve the efficiency of the engine by adjusting the optimum intake amount or exhaust timing according to the engine operating conditions, A reduction effect can be obtained.

The time when the suction and exhaust valve 280 is closed will be determined by the relative positions of the circulation flow path 65 and the second communication path 30 of the auxiliary discharge path 68 formed in the piston 60.

Generally, it is desirable that the engine optimize the intake or exhaust conditions to improve the fuel efficiency, as well as optimize the thermal efficiency and the output according to the conditions such as the operation speed and the load.

Therefore, conventionally, a variable valve timing device is used in which a cam profile is designed and manufactured in accordance with a high load condition of an engine, and then the valve opening timing is adjusted by changing the phase of the cam under a low load condition of the engine.

Meanwhile, according to the present invention, the cam profile is designed and manufactured in accordance with the low load condition of the engine, and then the variable valve timing (VVT) is not operated under the engine low load condition as shown in FIG. 7 off, so that a normal valve profile such as the 'a' graph is formed.

However, under the high load condition of the engine, the variable valve timing is activated (VVT on) to adjust the closing timing of the valve.

6, when the second communication passage 30 is opened so that the oil is also discharged through the second communication passage 30, the upper chamber 12 is opened before the piston 60 reaches the top dead center, The push rod lifter 41 is moved downward before the piston 60 reaches the top dead center so that the suction and exhaust valve 280 is moved to the normal And to close it earlier than the time.

For example, when the closing timing of the intake valve 280 is advanced, the second half of the graph 'a' in the normal operation moves as shown by an arrow 360, as shown in FIG. 7, So that the Miller Timing is realized, thereby providing the optimum valve timing to the operating conditions of the engine.

In the meantime, according to the present invention, the opening / closing valve 37 for opening / closing the second communication path 30 is connected to the main controller of the engine, so that it can be quickly adjusted according to the speed of the engine,

Therefore, according to the present invention, the oil is selectively circulated along two different first and second communication paths (20, 30), whereby the downward movement time of the push-rod lifter (41) It is possible to adjust the closing timing of the intake and exhaust valve 280 according to the engine speed, load conditions, and the like, thereby improving the efficiency and power of the engine and reducing the harmful substances in the exhaust gas such as NOx .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

Description of the Related Art [0002]
10: actuator housing 12: upper chamber
13: lower chamber 15: connecting chamber
16: Oil inlet 17,45: Check valve
20: first communication passage 30: second communication passage
31: upper flow path 33: lower flow path
35: connecting flow path 37: opening / closing valve
40: push rod lifting part 41: push rod lifter
42: push rod region 43: spring
45: Check valve 46: Pressure face
47: groove 50: return spring
60: piston 62: main exhaust passage
63: piston rod supporting surface 65: circulation flow path
66: Drain hole 68: Second exhaust path
100: variable valve timing device
200: camshaft 220: swing arm
230: Piston rod 250: Push rod
260: rocker arm 280: suction / exhaust valve

Claims (6)

An actuator housing having an upper chamber and a lower chamber and a connecting chamber connecting the upper chamber and the lower chamber;
A first communication path communicating the side surfaces of the upper chamber and the lower chamber with each other;
A second communication path connecting the first communication path and the lower side surface of the lower chamber with an opening / closing valve;
A push rod lifting unit installed in the upper chamber so as to be able to move up and down and to open and close the first communication path according to the lifting operation and to prevent the oil from moving to the lower chamber through the connection chamber;
A return spring installed in the lower chamber; And
A piston which is installed on the lower side of the return spring and opens and closes the lower end of the second communication path according to the lifting operation and discharges the oil of the second communication path;
And the variable valve timing device. The method according to claim 1,
The push rod lifting portion,
A push rod lifter installed in the upper chamber so as to be able to lift and lower the first communication path; And
A check valve elastically supported by a spring provided below the push rod lifter and coupled to an upper portion of the connecting chamber to block oil from moving to the lower chamber;
And the variable valve timing device. 3. The method of claim 2,
The piston has a main exhaust passage for downwardly discharging oil in the lower chamber so as to supply oil to the piston rod connected to the lower side, and an auxiliary exhaust passage for exhausting the oil of the second communication passage downwardly And the variable valve timing device. The method of claim 3,
Wherein the auxiliary discharge passage
A circulation channel having a predetermined depth formed in an annular shape along an outer circumferential surface of the piston; And
A drain hole for discharging the oil flowing into the circulation channel downward;
And the variable valve timing device. 5. The method of claim 4,
And a plurality of drain holes are provided at regular intervals along the circulation flow passage. 6. The method according to any one of claims 1 to 5,
Wherein the second communication path includes an upper flow path and a lower flow path, and a connection flow path connecting the upper flow path and the lower flow path, wherein the opening / closing valve is slidably inserted into the connection flow path to block the movement of the oil. Timing device.

Images