JP2006299916A - Variable valve mechanism for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately change over valve lift in three stages by a change over device of a small size/light weight simple structure change over device. <P>SOLUTION: The change over device 21 for a variable valve mechanism is provided with a first change over pin 22 connecting a first rocker arm 11 to a second rocker arm 12, a first spring 29 energizing the first change over pin 22 toward separation position, a second change over pin 23 connecting the second rocker arm 12 to a third rocker arm 13, and a second spring 32 energizing the second change over pin 23 toward a separation position by energizing force stronger than a first spring 29. An oil chamber 24 storing a first change over pin 22 is formed in the first rocker arm 11, and a piston 25 driving the second change over pin 23 is stored in a through hole of the first change over pin 22. A hydraulic circuit 34 selectively supplies low pressure oil or high pressure oil to the oil chamber 24 through an oil line 35 of the rocker shaft 4, the first change over pin 22 is driven to a connection position by low pressure oil and both of the change over pins 22, 23 are driven to the connection position by high pressure oil. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a variable valve mechanism for an internal combustion engine that switches a valve lift amount in three stages according to the operating state of the internal combustion engine.

  Conventionally, a variable motion equipped with a switching device that switches the intake valve opening and closing timing and lift amount to three stages for low speed, medium speed, and high speed by disconnecting or connecting the three rocker arms supported by the rocker shaft. A valve mechanism is known. For example, the variable valve mechanism described in Patent Document 1 includes a switching device 50 as shown in FIG. The switching device 50 includes a low-speed / medium-speed switching pin 54 that connects the first rocker arm 51 to the second rocker arm 52, a spring 55 that urges the switching pin 54 toward the separation position, and a second rocker arm 52. A medium speed / high speed switching pin 56 connected to the third rocker arm 53, a spring 57 that urges the switching pin 56 toward the separation position, and a hydraulic circuit that drives the two switching pins 54, 56 to the connection position. 58.

  During low-speed operation of the internal combustion engine, as shown in FIG. 10A, the hydraulic circuit 58 stops the supply of pressure oil, and the two switching pins 54 and 56 are held in the separated positions by the springs 55 and 57, The three rocker arms 51, 52, 53 are separated from each other. In this state, the low speed cam 60 on the camshaft 59 swings the first rocker arm 51, the pause cam 61 slightly swings the second rocker arm 52, and the high speed cam 62 swings the third rocker arm 53 idle. Then, the second rocker arm 52 holds one intake valve 63 in a resting state in which the lift amount R0 is substantially zero, and the first rocker arm 51 opens and closes the other intake valve 64 with a small lift amount R1. Performs lean combustion with low fuel consumption, and generates low-speed torque.

  During medium speed operation of the internal combustion engine, as shown in FIG. 10 (b), the pressure oil 65 passes through one oil passage 67 of the rocker shaft 66 and is supplied to one oil chamber 68 of the first rocker arm 51. Drive. The piston 69 drives the low speed / medium speed switching pin 54 to the coupling position, and the first rocker arm 51 is coupled to the second rocker arm 52 via the switching pin 54. No pressure oil is supplied to the other oil passage 70 of the rocker shaft 66, and the medium speed / high speed switching pin 56 is held in the disconnected position. Then, in a state where the third rocker arm 53 swings idle, the low speed cam 60 swings the first and second rocker arms 51 and 52 together, and the first rocker arm 51 opens and closes the intake valve 64 with a small lift amount R1. The second rocker arm 52 opens and closes the intake valve 63 with a small lift amount R1, and the internal combustion engine generates a medium speed torque.

  During high speed operation of the internal combustion engine, as shown in FIG. 10C, the pressure oil 65 is supplied to both the oil chambers 68 and 71 of the first rocker arm 51 through the two oil passages 67 and 70 of the rocker shaft 66. The two pistons 69 and 72 are driven. The piston 69 drives the low speed / medium speed switching pin 54 to the coupling position, and the piston 72 drives the medium speed / high speed switching pin 56 to the coupling position. As a result, the first rocker arm 51 is connected to the second rocker arm 52 via the switching pin 54, and the second rocker arm 52 is connected to the third rocker arm 53 via the switching pin 56. Then, the high-speed cam 62 swings the three rocker arms 51, 52 and 53 integrally, the first rocker arm 51 opens and closes the intake valve 64 with a large lift amount R2, and the second rocker arm 52 similarly increases the intake valve 63. The internal combustion engine generates high-speed torque by opening and closing with the lift amount R2.

Patent Document 2 describes a switching device in which a low speed / medium speed switching pin and a medium speed / high speed switching pin are arranged on the same axis in a variable valve mechanism that switches a valve lift amount in three stages. In this switching device, the hydraulic circuit that drives the switching pin to the coupling position has a first piston that drives the low / medium speed switching pin, a second piston that drives the medium / high speed switching pin, and each piston separately. It is comprised from the two oil chambers to accommodate, and the two oil paths which supply pressure oil separately to each oil chamber. The piston, the oil chamber, and the oil passage are provided on a pair of supports that support the rocker shaft.
JP 11-287139 A Japanese Patent Laid-Open No. 11-141322

  However, according to the switching device 50 of Patent Document 1, in order to switch the lift amount of the intake valves 63 and 64 in three stages, it is necessary to arrange the two switching pins 54 and 56 at two locations on the rocker arms 51, 52 and 53. There is a problem that the rocker arms 51, 52, 53 are enlarged and the mass is increased. Further, in order to supply the pressure oil 65 to the switching pins 54 and 56, it is necessary to provide the two oil passages 67 and 70 in the rocker shaft 66, and there is a problem that the configuration of the hydraulic circuit 58 becomes complicated. . The switching device of Patent Literature 2 can reduce the size and weight of the rocker arm by arranging two switching pins on the same axis. However, it is necessary to provide a piston, an oil chamber, and an oil passage that constitute the hydraulic circuit in the support, and there is a problem that the structure of the support is complicated and the processing cost is high.

  An object of the present invention is to enable an internal combustion engine that can solve the above-mentioned problems, reduce the installation space of the switching device, reduce the size and weight of the rocker arm, and simply configure the hydraulic circuit that drives the switching pin. It is to provide a variable valve mechanism.

  In order to solve the above-described problems, a variable valve mechanism for an internal combustion engine according to the present invention is a switching device that disconnects or connects three rocker arms supported by a rocker shaft and switches the lift amount of the valve in three stages. In the variable valve mechanism for an internal combustion engine, the switching device biases the first switching pin toward the disconnected position, and the first switching pin that detachably connects the first rocker arm to the second rocker arm. A first spring, a second switching pin that detachably connects the second rocker arm to the third rocker arm, a second spring that biases the second switching pin toward the separating position, a first switching pin, and a second A hydraulic circuit that drives the switching pin to the coupling position, and an oil chamber is formed in the first rocker arm, and a cylindrical first switching pin having a through hole is slidably received in the oil chamber, One changeover pin A piston for driving the second switching pin is slidably received in the through hole of the first hole, the biasing force of the second spring is set larger than the biasing force of the first spring, and the hydraulic circuit is attached to the first spring. Low pressure oil that drives the first switching pin against the force and high pressure oil that drives the first switching pin and the piston against the biasing force of the first and second springs It is configured to selectively supply the oil chamber through an oil passage.

Preferably, the variable valve mechanism can be combined with the following means.
(1) A storage chamber is formed in the second rocker arm, and a cylindrical pusher having a through hole is slidably received in the storage chamber, and the first switching pin is biased through the pusher. The first spring is mounted, and the second switching pin is slidably inserted into the through hole of the pusher.
(2) The second spring that forms a storage chamber in the third rocker arm, slidably stores a cylindrical pusher in the storage chamber, and biases the second switching pin through the pusher. Wear.
(3) The hydraulic circuit includes a hydraulic controller that switches the pressure of the pressure oil supplied from the pressure oil supply source between high and low levels.
(4) The three rocker arms are supported on the rocker shaft at one end, and a switching device is installed at an intermediate portion between the cam engaging portion and the rocker shaft of each rocker arm.
(5) A switching device is installed at one end of the three rocker arms, and each rocker arm is supported on the rocker shaft at an intermediate portion between the cam engaging portion and the switching device.

  According to the variable valve mechanism of the present invention, since the piston that drives the second switching pin is accommodated in the through hole of the first switching pin, the first switching pin and the second switching pin can be arranged on the same axis, and the switching device The installation space can be reduced and the three rocker arms can be made smaller and lighter. In addition, since the two switching pins are selectively controlled by low-pressure oil or high-pressure oil, the hydraulic circuit can be easily configured by one oil chamber and one oil passage, and the valve lift amount can be reduced by the hydraulic circuit. You can switch to the exact stage.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. As shown in FIG. 1, the variable valve mechanism 1 of this embodiment includes a switching device 21 driven by hydraulic pressure, and the switching device 21 supports three rocker arms 11, 12, 13 supported on a rocker shaft 4. The lift amount of the intake valves 8 and 9 is switched to three stages. As shown in FIG. 3, the switching device 21 includes a first switching pin 22 that detachably connects the first rocker arm 11 to the second rocker arm 12, and biases the first switching pin 22 toward the separation position. A first spring 29, a second switching pin 23 that detachably connects the second rocker arm 12 to the third rocker arm 13, and a second spring 32 that urges the second switching pin 23 toward the separating position. And a hydraulic circuit 34 for driving the first and second switching pins 22 and 23 to the coupling position.

  The urging force of the second spring 32 is set larger than the urging force of the first spring 29, and the two springs 23, 29 and the two switching pins 22, 23 are arranged on the same axis. The first rocker arm 11 is formed with one oil chamber 24 that houses the first switching pin 22, and a piston 25 that drives the second switching pin 23 is accommodated inside the first switching pin 22. The hydraulic circuit 34 includes a single oil passage 35 provided in the rocker shaft 4 and a hydraulic controller 40 that switches the pressure of the pressure oil supplied from the pressure oil supply source 37 in two steps, high and low, as shown in FIG. As described above, the low oil pressure 42 or the high oil pressure 43 is selectively supplied to the oil chamber 24 through the oil passage 35, and the first switching pin 22 is driven against the urging force of the first spring 29 by the low pressure oil 42. The first switching pin 22 and the piston 25 are driven against the urging force of the first and second springs 29 and 32 by the high-pressure oil 43.

  Next, Embodiment 1 of the present invention will be described with reference to FIGS. FIGS. 1 and 2 show a variable valve mechanism of a four-valve internal combustion engine for an automobile having two intake valves and two exhaust valves per cylinder. The number of cylinders of the internal combustion engine is not particularly limited, and a variable valve mechanism of a four-cylinder or six-cylinder internal combustion engine can be configured by arranging the necessary number of devices in the illustrated example. Although the illustrated example shows a variable valve mechanism for an intake valve, the same mechanism can be applied to an exhaust valve.

  The variable valve mechanism 1 according to the first embodiment includes a support 2 on a cylinder head (not shown) of an internal combustion engine. A camshaft 3 and a rocker shaft 4 are supported on the support 2 in parallel. The camshaft 3 is provided with a pause cam 5 having a substantially zero lift amount, a low speed cam 6 having a small lift amount, and a high speed cam 7 having a large lift amount. On the rocker shaft 4, three rocker arms 11, 12, and 13 driven by cams 5, 6, and 7 are arranged in that order and supported at each base end portion (one end portion in the longitudinal direction) so as to be swingable. Yes.

  The first rocker arm 11 is provided with a roller 14 that engages with the pause cam 5 at an intermediate portion, and a pressing portion that presses one intake valve 8 at a tip portion. The second rocker arm 12 is provided with a roller 15 that engages with the low-speed cam 6 at an intermediate portion, and a pressing portion that presses the other intake valve 9 at a tip portion. The third rocker arm 13 is provided with a roller 16 that engages with the high-speed cam 7 but is not provided with a pressing portion so that the intake valves 8 and 9 are not directly driven. The rollers 14, 15, and 16 are cam engaging portions of the rocker arms 11, 12, and 13. However, instead of the rollers 14, 15, and 16, a hard tip can be used for the cam engaging portion.

  Three rocker arms 11, 12, 13 at the intermediate portion between the rocker shaft 4 and the rollers 14, 15, 16 have three timings for opening and closing the intake valves 8, 9 and lift amounts for low speed, medium speed, and high speed. A switching device 21 for switching to a stage is installed. As shown in FIG. 3, the switching device 21 includes a low-speed / medium-speed switching pin (first switching pin) 22 that detachably connects the first rocker arm 11 to the second rocker arm 12, and the second rocker arm 12. A medium-speed / high-speed switching pin (second switching pin) 23 detachably connected to the three rocker arms 13 is provided on one axis A extending in parallel with the rocker shaft 4 (at the time of zero lift).

  The first rocker arm 11 is formed with a bottomed circular hole-shaped oil chamber 24 from the side facing the second rocker arm 12, and the oil chamber 24 has a smaller-diameter inlet formed in a stepped manner inside the accommodating chamber 24 a. It comprises an oil chamber 24b. The low-speed / medium-speed switching pin 22 is formed in a cylindrical shape having the same length as the accommodation chamber 24a and having an axial through hole, and is accommodated in the accommodation chamber 24a so as to be slidable in the axis A direction. A through-hole of the low-speed / medium-speed switching pin 22 accommodates a piston 25 that transmits hydraulic pressure, which will be described later, and drives the medium-speed / high-speed switching pin 23 so as to be slidable in the direction of the axis A. It is formed in a cylindrical shape having the same length as the pin 22. Thus, the low speed / medium speed switching pin 22 and the piston 25 have a concentric double structure.

  The second rocker arm 12 is formed with a bottomed circular hole-shaped storage chamber 27 from the side facing the first rocker arm 11. The diameter of the storage chamber 27 is the same as that of the storage chamber 24a, and the low speed / medium speed switching pin 22 can enter. A wall hole 26 is formed in the wall of the second rocker arm 12 facing the third rocker arm 13. A pusher 28 that contacts the end face of the low-speed / medium-speed switching pin 22 is accommodated in the accommodation chamber 27 so as to be slidable in the axis A direction. It is formed in a cylindrical shape. A first spring 29 is installed between the pusher 28 and the wall of the second rocker arm 12 to urge the low-speed / medium-speed switching pin 22 toward the separation position on the first rocker arm 11 side via the pusher 28. ing. A medium speed / high speed switching pin 23 is slidably inserted in the direction of the axis A through the through hole of the pusher 28 and the wall hole 26 of the second rocker arm 12. It is formed in a cylindrical shape having the same length and the same diameter as the piston 25. Thus, the medium speed / high speed switching pin 23 and the pusher 28 have a concentric double structure.

  The third rocker arm 13 is formed with a bottomed circular hole-shaped storage chamber 30 from the side facing the second rocker arm 12. The diameter of the storage chamber 30 is the same as that of the wall hole 26, and the medium speed / high speed switching pin 23 can be inserted. In the storage chamber 30, a pusher 31 that comes into contact with the end surface of the medium / high speed switching pin 23 is accommodated so as to be slidable in the direction of the axis A. . Between the pusher 31 and the wall of the third rocker arm 13, a second spring 32 that urges the medium speed / high speed switching pin 23 toward the separation position on the second rocker arm 12 side through the pusher 31 is mounted. ing. The urging force of the second spring 32 is set to be larger than the urging force of the first spring 29, and the low / medium speed switching pin 22 compresses the first spring 29 to connect the first rocker arm 11 and the second rocker arm 12. The medium-speed / high-speed switching pin 23 compresses the second spring 29 and slides to a connection position straddling the second rocker arm 12 and the third rocker arm 13.

  The switching device 21 is provided with a hydraulic circuit 34 that drives the two switching pins 22 and 23 to the coupling position. The hydraulic circuit 34 includes a single oil passage 35 formed in the rocker shaft 4, a communication passage 36 that connects the oil passage 35 to the oil chamber 24 of the first rocker arm 11, and the oil passage 35 is a pressure oil supply source. A pipe 38 connected to the pump 37 and a hydraulic controller 40 electrically connected to an automobile electronic control unit (ECU) 39 are provided. Then, the pressure of the oil discharged from the pump 37 is switched between two levels, high and low, by the hydraulic controller 40, and low pressure oil or high pressure oil is selectively supplied to the oil chamber 24 via the pipe 38, the oil path 35, and the communication path 36. Only the low speed / medium speed switching pin 22 is driven to the coupling position by oil, and both the low speed / medium speed switching pin 22 and the medium speed / high speed switching pin 23 are driven to the coupling position by high pressure oil.

  Next, the operation of the variable valve mechanism 1 configured as described above will be described. During low-speed operation of the internal combustion engine, as shown in FIG. 4A, in the switching device 21, the supply of pressure oil is stopped, and the two switching pins 22 and 23 are held in the separated positions by the springs 29 and 32. The three rocker arms 11, 12, 13 are separated from each other. In this state, the pause cam 5 slightly swings the first rocker arm 11, the low speed cam 6 swings the second rocker arm 12, and the high speed cam 7 swings the third rocker arm 13 idle. The first rocker arm 11 holds the lift amount R0 of one intake valve 8 substantially at zero, the second rocker arm 12 opens and closes the other intake valve 9 with a small lift amount R1, and the internal combustion engine consumes fuel. It performs lean combustion with a small amount of torque and generates torque suitable for low-speed operation.

  During medium speed operation of the internal combustion engine, as shown in FIG. 4B, the low pressure oil 42 is supplied to the oil chamber 24 of the first rocker arm 11 through the oil passage 35 and the communication passage 36, and the low speed / medium speed switching pin. 22 compresses the first spring 29 and is driven to the coupling position, and the first rocker arm 11 is coupled to the second rocker arm 12 via the switching pin 22. At this time, the second spring 32 stops the medium speed / high speed switching pin 23 at the separation position against the pressure of the low pressure oil 42, and holds the second rocker arm 12 and the third rocker arm 13 in the separated state. Then, the first rocker arm 11 and the second rocker arm 12 are integrally swung by the low speed cam 6 while the third rocker arm 13 is swung freely, and both the intake valves 8 and 9 are opened and closed with a small lift amount R1, The internal combustion engine generates torque suitable for medium speed operation.

  During high speed operation of the internal combustion engine, as shown in FIG. 4C, high pressure oil 43 is supplied to the oil chamber 24, and the low speed / medium speed switching pin 22 and the piston 25 are simultaneously driven by the high pressure oil 43. Then, the low speed / medium speed switching pin 22 slides to the connecting position to connect the first rocker arm 11 to the second rocker arm 12, and the medium speed / high speed switching pin 23 is driven by the piston 25 so that the second spring 32 is moved. The second rocker arm 12 is coupled to the third rocker arm 13 by compressing and sliding to the coupling position. Then, the three rocker arms 11, 12, and 13 are connected to each other and rocked together by the high-speed cam 7, and the intake valves 8 and 9 are both opened and closed with a large lift amount R2, so that the internal combustion engine can be operated at high speed. Generate suitable torque.

  According to the variable valve mechanism 1 of the first embodiment, since the piston 25 that drives the medium / high speed switching pin 23 is accommodated in the through hole of the low / medium speed switching pin 22, The medium-speed / high-speed switching pins 23 can be arranged on the same axis at one location of the rocker arms 11, 12, 13, and the installation space for the switching device 21 is reduced. For this reason, the three rocker arms 11, 12, and 13 can be manufactured in a smaller size than the conventional one, and the mass thereof can be reduced. Further, the pressure of the pressure oil is switched in two stages by the hydraulic controller 40, and the low pressure oil 42 or the high pressure oil 43 is selectively supplied to the oil chamber 24. Therefore, the oil path on the support 2 side is omitted and the oil path of the rocker shaft 4 is removed. The hydraulic circuit 34 can be configured easily and inexpensively by reducing the number 35 to one, and the hydraulic circuit 34 controls the two switching pins 22 and 23 to accurately adjust the lift amount of the intake valves 8 and 9 in three stages. You can switch to

  5 and 6 show a second embodiment of the present invention. The variable valve mechanism 45 has one intake valve 8 attached to the first rocker arm 11 and the other intake valve 9 attached to the third rocker arm 13, so that the intake valves 8, 9 are operated during low speed operation and medium speed operation. Is configured to open and close with a lift amount different from that of the first embodiment. The arrangement of the cams 5, 6 and 7 and the configuration of the switching device 21 are the same as those in the first embodiment.

  During low-speed operation of the internal combustion engine, as shown in FIG. 6A, the switching device 21 separates the three rocker arms 11, 12, and 13 from each other, and the first rocker arm 11 is slightly swung by the pause cam 5, The two rocker arms 12 are swung by the low speed cam 6, and the third rocker arm 13 is swung by the high speed cam 7. The first rocker arm 11 keeps the lift amount R0 of the intake valve 8 substantially zero, the third rocker arm 13 opens and closes the intake valve 9 with a large lift amount R2, and the internal combustion engine is larger than that in the first embodiment. Generate low speed torque.

  During medium speed operation of the internal combustion engine, the switching device 21 connects the first rocker arm 11 to the second rocker arm 12 and disconnects the third rocker arm 13 from the second rocker arm 12 as shown in FIG. Then, the first rocker arm 11 and the second rocker arm 12 are integrally swung by the low speed cam 6, the intake valve 8 is opened and closed with a small lift amount R 1, and the third rocker arm 13 is swung independently by the high speed cam 7. The valve 9 is opened and closed with a large lift amount R2, and the internal combustion engine generates a larger medium speed torque than in the first embodiment. During high-speed operation, as shown in FIG. 6C, a valve lift amount equivalent to that in the first embodiment is ensured.

  7 and 8 show Embodiment 3 of the present invention. In this variable valve mechanism 47, the two intake valves 8 and 9 are both attached to the T-shaped arm 48 of the first rocker arm 11, so that the valve lift amount can be switched to three stages: pause, low speed, and high speed. It is configured. The arrangement of the cams 5, 6 and 7 and the configuration of the switching device 21 are the same as those in the first embodiment.

  When a specific cylinder is deactivated in a multi-cylinder internal combustion engine, as shown in FIG. 8A, the switching device 21 separates the three rocker arms 11, 12, and 13 from each other, and the deactivation cam 5 serves as the first rocker arm. 11, the first rocker arm 11 holds the intake valves 8 and 9 in a resting state in which the lift amount R0 is substantially zero. During low speed operation of the internal combustion engine, as shown in FIG. 8B, the switching device 21 connects the first rocker arm 11 to the second rocker arm 12, and the low speed cam 6 swings both the rocker arms 11, 12 together. The first rocker arm 11 opens and closes the intake valves 8 and 9 with a small lift amount R1. During high-speed operation, as shown in FIG. 8C, the switching device 21 connects the three rocker arms 11, 12, 13 to each other, and the high-speed cam 7 swings the rocker arms 11, 12, 13 together. The first rocker arm 11 opens and closes the intake valves 8 and 9 with a large lift amount R2.

The present invention is not limited to the above-described embodiments. For example, as described below, the present invention can be appropriately modified and embodied without departing from the spirit of the invention.
(1) As shown in FIG. 9, a switching device 49 is installed at one longitudinal end of the three rocker arms 11, 12, 13, and each rocker arm 11, 12, 13 is connected to the rollers 14, 15, 16 and the switching device 49. You may support to the rocker shaft 4 in the intermediate part.
(2) The cam profile of the cams 5, 6 and 7 and the arrangement order thereof are changed, for example, by providing a cam with a nose portion on the camshaft 3 instead of the pause cam 5 shown in FIG.

It is a perspective view of the variable valve mechanism which shows Example 1 of this invention. It is a right view of FIG. It is the III-III sectional view taken on the line of FIG. 2 which shows a switching apparatus. It is operation | movement explanatory drawing of the variable valve mechanism of Example 1. FIG. It is a perspective view of the variable valve mechanism which shows Example 2 of this invention. It is operation | movement explanatory drawing of the variable valve mechanism of Example 2. FIG. It is a perspective view of the variable valve mechanism which shows Example 3 of this invention. It is operation | movement explanatory drawing of the variable valve mechanism of Example 3. FIG. It is a side view of the variable valve mechanism which shows another example of installation of a switching apparatus. It is operation | movement explanatory drawing of the conventional variable valve mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Variable valve mechanism 4 Rocker shaft 8 Intake valve 9 Intake valve 11 1st rocker arm 12 2nd rocker arm 13 3rd rocker arm 21 Switching device 22 Low speed / medium speed switching pin 23 Medium speed / High speed switching pin 24 Oil chamber 29 First spring 32 Second spring 34 Hydraulic circuit 35 Oil path 40 Hydraulic controller 42 Low pressure oil 43 High pressure oil 45 Variable valve mechanism 47 Variable valve mechanism 49 Switching device

Claims (3)

In a variable valve mechanism for an internal combustion engine having a switching device for switching the lift amount of a valve in three stages by disconnecting or connecting the three rocker arms supported by the rocker shaft to each other,
The switching device urges the first switching pin (22) to detachably connect the first rocker arm (11) to the second rocker arm (12) and the first switching pin (22) toward the separation position. The first spring (29), the second switching pin (23) for detachably connecting the second rocker arm (12) to the third rocker arm (13), and the second switching pin (23) in the disconnected position. A second spring (32) that urges toward the first and a hydraulic circuit that drives the first switching pin (22) and the second switching pin (23) to the coupling position;
An oil chamber (24) is formed in the first rocker arm (11), and a cylindrical first switching pin (22) having a through hole is slidably accommodated in the oil chamber (24). A piston (25) for driving the second switching pin (23) is slidably accommodated in the through hole of the pin (22),
The biasing force of the second spring (32) is set larger than the biasing force of the first spring (29);
The hydraulic circuit is against low pressure oil for driving the first switching pin (22) against the biasing force of the first spring (29) and against the biasing force of the first and second springs (29, 32). High pressure oil for driving the first switching pin (22) and the piston (25) is selectively supplied to the oil chamber (24) through a single oil passage (35) on the rocker shaft (4). A variable valve mechanism for an internal combustion engine, characterized in that:   A storage chamber (27) is formed in the second rocker arm (12), and a cylindrical pusher (28) having a through hole is slidably received in the storage chamber (27), and the pusher (28). The first spring (29) for urging the first switching pin (22) is mounted via the first switching pin (22), and the second switching pin (23) is slidably inserted into the through hole of the pusher (28). Item 6. A variable valve mechanism for an internal combustion engine according to Item 1.   A storage chamber (30) is formed in the third rocker arm (13), and a cylindrical pusher (31) is slidably received in the storage chamber (30), and the pusher (31) is used to The variable valve mechanism for an internal combustion engine according to claim 2, wherein the second spring (32) for biasing the second switching pin (23) is mounted.

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