JP2007146679A - Valve gear of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure a large change quantity of a valve lift of an engine valve by a hydraulic actuator of a small stroke. <P>SOLUTION: In this valve gear, a rocker arm 15 is composed of a first rocker arm 16 pivoted on a rocker shaft 18 and abutting on the engine valve 11, and a second rocker arm 17 pivoted on the rocker shaft 18 and abutting on a valve system cam 14. Since a relative angle of the first and second rocker arms 16 and 17 is changed by the hydraulic actuator 30, a lift changing quantity of the engine valve 11 can be sufficiently secured by the hydraulic actuator 30 of the small stroke. Moreover, since the hydraulic actuator 30 is arranged nearer to the rocker shaft 18 than a valve driving part 16a of the first rocker arm 16, rigidity of the rocker arm 15 is secured by arranging the hydraulic actuator 30 being a heavy load in the vicinity of the rocker shaft 18, and an internal combustion engine can be operated at a high speed by reducing the moment of inertia of the rocker arm 15. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a valve operating apparatus for an internal combustion engine that opens and closes an engine valve by swinging a rocker arm pivotally supported by a rocker shaft by a valve operating cam.

One end of a rocker arm pivotally supported on the rocker shaft in the longitudinal direction is brought into contact with the valve cam, and the other end is brought into contact with the stem end of the engine valve via a hydraulic actuator, Patent Document 1 below discloses that a hydraulic actuator can be extended and retracted to change the valve lift and valve timing of an engine valve steplessly.
JP 2004-44399 A

  However, since the hydraulic actuator for changing the valve lift and valve timing of the engine valve is provided at the end of the rocker arm, the stroke of the hydraulic actuator is substantially equal to the lift change amount of the engine valve as it is. Thus, there is a problem that it is difficult to secure a sufficient amount of change in lift of the engine valve.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to ensure a large amount of change in the valve lift of an engine valve with a small stroke hydraulic actuator.

  In order to achieve the above object, according to the first aspect of the present invention, in a valve operating apparatus for an internal combustion engine that opens and closes an engine valve by swinging a rocker arm pivotally supported by a rocker shaft by a valve operating cam, A first rocker arm that swings about the rocker shaft and contacts the engine valve; a second rocker arm that swings about the rocker shaft and contacts the valve cam; and the first and second rockers A hydraulic actuator provided between the arms and configured to change a relative angle between the first and second rocker arms; and a hydraulic control means for controlling a hydraulic pressure supplied to the hydraulic actuator, wherein the hydraulic actuator includes the first rocker Provided closer to the rocker shaft than the point where the arm contacts the engine valve or the point where the second rocker arm contacts the valve cam. A valve gear of an internal combustion engine, characterized in Rukoto is proposed.

  According to the invention described in claim 2, in addition to the structure of claim 1, the hydraulic control means is provided inside the rocker shaft. A valve gear is proposed.

  The control valve 46 in the embodiment corresponds to the hydraulic control means of the present invention.

  According to the first aspect of the present invention, the first rocker arm pivotally supported by the rocker shaft and abutting the engine valve and the second rocker arm pivotally supported by the rocker shaft and abutted by the valve cam are provided, Since the hydraulic actuator provided between the second rocker arms is expanded and contracted by the hydraulic control means to change the relative angle between the first and second rocker arms, the hydraulic actuator with a small stroke can sufficiently change the valve lift of the engine valve. Can be secured. In addition, since the hydraulic actuator is provided closer to the rocker shaft than the point where the first rocker arm abuts the engine valve or the point where the second rocker arm abuts the valve cam, the heavy hydraulic actuator is attached to the rocker shaft. It is possible to secure the rigidity of the rocker arm by arranging it in the vicinity, and to reduce the moment of inertia of the rocker arm, thereby enabling high speed operation of the internal combustion engine.

  According to the configuration of the second aspect, since the hydraulic control means is provided inside the rocker shaft, the oil passage connecting the hydraulic control means to the hydraulic actuator can be effectively shortened.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples of the present invention shown in the accompanying drawings.

  1 to 9 show an embodiment of the present invention. FIG. 1 is a plan view of a valve operating mechanism, FIG. 2 is a sectional view taken along line 2-2 of FIG. 1, and FIG. 4 is a sectional view taken along line 4-4 of FIG. 3, FIG. 5 is a perspective view of a rocker arm and a rocker shaft, FIG. 6 is a hydraulic circuit diagram for driving a hydraulic actuator, and FIG. FIG. 8 is an operation explanatory diagram corresponding to FIG. 2, and FIG. 9 is a diagram showing variable characteristics of valve lift and valve timing.

  1 to 3 show a valve mechanism 12 for opening and closing an engine valve 11 (intake valve or exhaust valve) of an internal combustion engine. Two engine valves 11 and 11 of a common cylinder are provided on a camshaft 13. The two valve cams 14 and 14 are driven to open and close via rocker arms 15 and 15, respectively. Since the valve mechanisms 12 of the two engine valves 11 and 11 have the same structure, one structure will be described below.

  As apparent from FIGS. 1 to 5, the rocker arm 15 includes a first rocker arm 16 and a second rocker arm 17, and the first rocker arm 16 is press-fitted into the rocker shaft 18, and the second rocker arm The bifurcated portion 17 is swingably supported by the rocker shaft 18 on both axial sides of the first rocker arm 16. The rocker shaft 18 is provided for each rocker arm 15, and two rocker shafts 18 corresponding to the two engine valves 11, 11 of the cylinder are arranged adjacent to each other on the same axis. That is, the first holder 20 and the first cap 21 are overlapped on the upper surface of the cylinder head 19 and fixed by the three bolts 22..., And the second holders 23 and 23 and the second caps 24 and 24 are disposed on both sides in the axial direction. They are overlapped and fixed with two bolts 25, 25 respectively. One rocker shaft 18 is installed between the first holder 20 and the first cap 21 and one second holder 23 and the second cap 24, and the other rocker shaft 18 is arranged between the first holder 20 and the first cap 21. And the other second holder 23 and the second cap 24. At this time, both ends of each rocker shaft 18 are sandwiched from above and below between the first holder 20 and the first cap 21 and between the second holder 23 and the second cap 24 and are rotatably supported.

  The first rocker arm 16 includes a valve drive portion 16a that abuts on the stem end 11a of the engine valve 11 urged in the valve closing direction by a valve spring 26, and an actuator cylinder 16b that is released at one end. The actuator piston 27 slidably fitted to the actuator is urged in the forward direction by a return spring 29 disposed in the working chamber 28 at the back thereof. The actuator cylinder 16b, the actuator piston 27, the working chamber 28, and the return spring 29 constitute a hydraulic actuator 30 that changes the relative angles of the first and second rocker arms 16 and 17. On the other hand, the second rocker arm 17 includes a roller 32 that is rotatably supported by a pin 31 and a piston abutting portion 17 a that abuts on an end surface of the actuator piston 27. When the position of the actuator piston 27 with respect to the actuator cylinder 16 b changes, the second rocker arm 17 swings relative to the first rocker arm 16 around the rocker shaft 18, so that the valve drive unit of the first rocker arm 16 The distance between 16a and the roller 32 of the second rocker arm 17 changes.

  A camshaft 13 connected to and driven by the crankshaft of the engine is rotatably supported on the upper surface of the cylinder head 19 by a first holder 20 and a first cap 21, and a valve cam provided on the camshaft 13. 14 contacts the roller 32 of the second rocker arm 17. Therefore, when the camshaft 13 rotates, the first rocker arm 16 swings about the rocker shaft 18 together with the second rocker arm 17 guided by the roller 32 to the valve cam 14, and the valve drive of the first rocker arm 16 is performed. The part 16a drives the engine valve 11 to open and close.

  As apparent from FIGS. 3, 4 and 6, a first cylinder hole 18a and a second cylinder hole 18b are formed inside the rocker shaft 18 with a partition wall 18c interposed therebetween. A communication hole 18d that allows the cylinder hole 18a and the second cylinder hole 18b to communicate with each other passes therethrough, the first cylinder hole 18a opens to one end side of the rocker shaft 18, and the second cylinder hole 18b opens to the other end side of the rocker shaft 18. The opening to be sealed is sealed with a blind plug 41.

  The accumulator 42 disposed in the first cylinder hole 18a of the rocker shaft 18 includes an accumulator piston 43 that is slidably fitted in the first cylinder hole 18a, and an accumulator that urges the accumulator piston 43 toward the partition wall 18c. A spring 44 and an accumulator chamber 45 formed on the front surface of the accumulator piston 43 are configured. The accumulator spring 44 and the accumulator chamber 45 are shared by the two accumulators 42 and 42 arranged in parallel.

  The control valve 46 disposed in the second cylinder hole 18b of the rocker shaft 18 is contracted between a piston-like valve body 47 that is slidably fitted in the second cylinder hole 18b and the blind plug 41. The return spring 48 biases the valve body 47 toward the partition wall 18 c, the valve chamber 49 defined between the valve body 47 and the partition wall 18 c, and the back chamber 50 at the back of the valve body 47. The valve chamber 49 communicates with the actuator cylinder 16 b via an oil hole 18 e that penetrates the rocker shaft 18 in the radial direction and an oil passage 16 c formed inside the first rocker arm 16. In addition, the valve body 47 is formed with an orifice 47a for communicating the inside and the outside.

  Since the working chamber 28 of the hydraulic actuator 30 and the back chamber 50 of the control valve 46 communicate with each other through an orifice 47a formed in the valve body 47, while substantially preventing the oil from flowing between the two chambers 28, 50, The pressures in the two chambers 28 and 50 can be matched.

  An electromagnetic valve 51 capable of controlling the opening degree steplessly is provided on the upper surface of the second cap 24. The electromagnetic valve 51 communicates with the back chamber 50 of the control valve 46 through the oil passage 24a of the second cap 24 and the oil passage 18f of the rocker shaft 18. When the electromagnetic valve 51 is opened, the back chamber 50 is connected to the cylinder head. 19 is open to the space inside. The electromagnetic valve 51 is controlled by an electronic control unit 53 to which a hydraulic sensor 52 that measures the hydraulic pressure of the back chamber 50 is connected.

  A first check valve 54 and a second check valve 55 are provided on both sides of the control valve 46 of the rocker shaft 18, and the inlet side of these first and second check valves 54, 55 is formed in the second holder 23. It is connected to the hydraulic pump 56 via an oil passage (not shown), oil passages 23 b and 24 c formed in the second cap 24, and oil passages 18 g and 18 h formed in the rocker shaft 18. The outlet side of the first check valve 54 is connected to the back chamber 50 of the control valve 46, and the outlet side of the second check valve 55 is connected to the rocker shaft 18 oil hole 18e.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  In FIG. 2, the engine valve 11 is urged in the valve closing direction by the elastic force of the valve spring 26, so that the rocker arm 15 whose valve drive unit 16 a is pressed against the stem end 11 a of the engine valve 11 is the rocker shaft 18. The roller 32 is urged counterclockwise and the roller 32 comes into contact with the valve cam 14. At this time, the actuator piston 27 is pressed by the piston contact portion 17a of the second rocker arm 17 and pushed into the actuator cylinder 16b, so that the hydraulic pressure generated in the working chamber 28 and the elastic force of the valve spring 26 are balanced. Then, the actuator piston 27 stops. The hydraulic pressure generated in the working chamber 28 is controlled by opening and closing the electromagnetic valve 51.

  In a state where the electromagnetic valve 51 is closed, the hydraulic actuator 30 working chamber 28 and the back chamber 50 of the control valve 46 communicate with each other via the orifice 47 a of the valve body 47, and the first and second rocker arms 16 and 17. The actuator piston 27 is locked in a state where the angle formed by is maintained at the maximum angle α. When the camshaft 13 rotates in this state and the valve cam 14 pushes the roller 32 of the second rocker arm 17, the hydraulic actuator 30 is locked, so the first and second rocker arms 16, 17 are integrated. The engine valve 11 is driven to open when the valve drive unit 16a of the first rocker arm 16 pushes down the stem end 11a. Thus, if the solenoid valve 51 is maintained in the closed state, the engine valve 11 is driven with the maximum lift and the maximum valve opening period (see solid lines in FIGS. 7 and 9).

  As apparent from FIG. 6, the valve cam 14 presses the roller 32 of the second rocker arm 17, and the piston contact portion 17 a of the second rocker arm 17 presses the actuator piston 27 of the first rocker arm 17. If the solenoid valve 51 is opened while the engine valve 11 is being lifted, the back chamber 50 of the control valve 46 is opened and the pressure is reduced. Therefore, the valve body of the control valve 46 is driven by the oil pushed out from the accumulator chamber 45. 47 retreats, the communication between the working chamber 28 and the back chamber 50 is cut off, and the working chamber 28 and the accumulator chamber 45 communicate with each other. As a result, the oil in the working chamber 28 flows into the accumulator chamber 45 while the actuator piston 27 pressed by the piston contact portion 17a of the second rocker arm 17 moves backward, and the hydraulic actuator 30 contracts. Thereby, since the angle formed by the first and second rocker arms 16 and 17 is reduced from α to β (see FIG. 8), the first rocker arm 16 cannot lift the engine valve 11 any more, Accordingly, the lift of the engine valve 11 can be delayed and the valve lift can be reduced.

  When the solenoid valve 51 is closed in the process in which the valve cam 14 presses the roller 32, the valve body 47 of the control valve 46 moves forward with oil supplied from the hydraulic pump 56 to the back chamber 50 via the first check valve 54. Then, the communication between the hydraulic actuator 30 and the accumulator 42 is cut off, so that the hydraulic actuator 30 is locked so as not to expand and contract. As a result, the first and second rocker arms 16 and 17 are integrated, and the engine valve 11 starts to lift.

  When the apex of the valve cam 14 moves over the roller 32, the piston contact portion 17a of the second rocker arm 17 does not press the actuator piston 27, so that the actuator piston 27 moves forward to the original position by the elastic force of the return spring 29. As a result, the angle formed by the first and second rocker arms 16 and 17 gradually increases, and the contact between the valve cam 14 and the roller 32 is ensured.

  Thus, the position of the actuator piston 27 is controlled steplessly by controlling the opening of the electromagnetic valve 51 steplessly, and the valve timing and valve lift of the engine valve 11 are controlled as shown by the broken line or the chain line in FIG. It can be controlled arbitrarily. The oil leaked through the orifice 47 a of the valve body 47 and the back chamber 50 while the electromagnetic valve 51 is opened is replenished from the hydraulic pump 56 via the second check valve 55.

  As described above, the rocker arm 15 is divided into the first and second rocker arms 16 and 17, and the angle formed by the first and second rocker arms 16 and 17 is changed by the hydraulic actuator 30. Since the relative positional relationship between the roller 32 that contacts the valve end 16a and the valve drive portion 16a that contacts the stem end 11a of the engine valve 11 is changed, the valve lift of the engine valve 11 can be increased even if the stroke of the hydraulic actuator 30 is set small. A large amount of change can be secured.

  Further, compared to the case where the hydraulic actuator 30 is provided at the tip of the rocker arm 15 (valve drive portion 16a) that contacts the stem end 11a of the engine valve 11, the heavy hydraulic actuator 30 can be disposed close to the rocker shaft 18. Therefore, it is possible to ensure the rigidity of the rocker arm 15 and to suppress the moment of inertia of the rocker arm 15 to be small and to operate the internal combustion engine at a high speed.

  In addition, since the control valve 46 and the accumulator 42 for controlling the hydraulic pressure of the hydraulic actuator 30 are provided inside the rocker shaft 18, the oil passage 16c connecting the control valve 46 and the accumulator 42 to the hydraulic actuator 30 is shortened, particularly at low temperatures. It is possible to improve the responsiveness by eliminating the influence of the oil viscosity.

  Although the embodiments of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.

  For example, although the hydraulic actuator 30 is provided on the first rocker arm 16 side in the embodiment, it may be provided on the second rocker arm 17 side.

Plan view of the valve mechanism 2-2 sectional view of FIG. 3-3 sectional view of FIG. Sectional view taken along line 4-4 in FIG. Perspective view of rocker arm and rocker shaft Hydraulic circuit diagram for driving the hydraulic actuator Action explanatory diagram corresponding to FIG. Action explanatory diagram corresponding to FIG. Diagram showing variable characteristics of valve lift and valve timing

Explanation of symbols

11 Engine valve 14 Valve cam 15 Rocker arm 16 First rocker arm 17 Second rocker arm 18 Rocker shaft 30 Hydraulic actuator 46 Control valve (hydraulic control means)

Claims (2)

In a valve operating apparatus for an internal combustion engine, which opens and closes an engine valve (11) by swinging a rocker arm (15) pivotally supported by a rocker shaft (18) by a valve operating cam (14),
A first rocker arm (16) that swings about the rocker shaft (18) and contacts the engine valve (11), and a valve cam (14) that swings about the rocker shaft (18). Hydraulic actuator provided between the abutting second rocker arm (17) and the first and second rocker arms (16, 17) and changing the relative angle of the first and second rocker arms (16, 17). (30) and hydraulic control means (46) for controlling the hydraulic pressure supplied to the hydraulic actuator (30),
The hydraulic actuator (30) is configured so that the first rocker arm (16) contacts the engine valve (11) or the second rocker arm (17) contacts the valve cam (14). Is also provided closer to the rocker shaft (18). 2. The valve operating apparatus for an internal combustion engine according to claim 1, wherein the hydraulic control means (46) is provided inside the rocker shaft (18).

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