JP4659583B2 - Variable valve mechanism - Google Patents

Description

  The present invention relates to a variable valve mechanism that controls valve characteristics in an internal combustion engine in which a plurality of cylinders are arranged.

  2. Description of the Related Art Conventionally, a variable valve mechanism that uses a link to control the lift amount, operating angle, and opening / closing timing of a valve is known. For example, the variable valve mechanism 100 of Patent Document 1 shown in FIG. 9 includes a camshaft 101 connected to a crankshaft of an internal combustion engine. A rotating cam 102 is fixed on the camshaft 101 so as to be integrally rotatable, and a swing cam 104 that opens and closes the valve 103 is supported so as to be relatively rotatable.

A swing arm 106 is supported via a variable cam 107 on a control shaft 105 parallel to the camshaft 101. The input end of the swing arm 106 is connected to the rotating cam 102 via a ring-shaped link 108, and the output end of the swing arm 106 is connected to the swing cam 104 via a rod-shaped link 109. The control shaft 105 is driven by an actuator, and the swing arm 106 is displaced by the eccentric rotation of the variable cam 107, so that the swing angle of the swing cam 104 is changed according to the operating state of the internal combustion engine. ing.
JP-A-11-324625

  However, according to the conventional variable valve mechanism 100, the swing cam 104 that opens and closes the valve 103 is supported on the rotating camshaft 101. Therefore, in order to swing the swing cam 104, the camshaft 101 and the swing cam 104 need to be connected by two long links 108 and 109. Further, in order to change the swing angle of the swing cam 104, the swing arm 106 is interposed between the two links 108 and 109, and the variable cam 107 is mounted on the control shaft 105 that supports the swing arm 106. It was also necessary to provide it.

  For this reason, there is a problem that the variable valve mechanism 100 is enlarged, the installation space is increased, the number of parts is increased, the configuration is complicated, and the valve characteristics are likely to become unstable due to an assembly error. In particular, in the case of a multi-cylinder internal combustion engine having a plurality of cylinders, for example, a gasoline engine having a two-bank structure, it is necessary to install the variable valve mechanisms 100 on the two camshafts 101 respectively. Due to the error of 100, there is a problem that variation in valve characteristics easily occurs between cylinders.

  An object of the present invention is to solve the above-described problems and provide a variable valve mechanism that can obtain stable valve characteristics with a small and simple configuration.

In order to solve the above-described problems, a variable valve mechanism according to the present invention includes a cam that opens and closes one of an intake valve and an exhaust valve provided in each cylinder in an internal combustion engine in which a plurality of cylinders are arranged. A camshaft, a drive means for swinging the camshaft around the axis of the shaft, and a variable means for changing the swing angle, which is the swing amount of the camshaft, according to the operating state of the internal combustion engine. A plurality of cams on the camshaft are equally provided on both sides at both ends of the swinging direction with respect to the shaft center of the shaft, and the driving means is rotated by the crankshaft of the internal combustion engine. A drive shaft, and a motion converting member that converts the rotational motion of the drive shaft into a swing motion of the camshaft, the drive shaft including the drive camshaft, and an intake valve on the drive camshaft. Or characterized in that a cam for opening and closing either other valve of the exhaust valve.
According to the configuration in which a plurality of cams are equally provided on both sides of both ends of the swinging direction with respect to the shaft center on the camshaft, the plurality of cams are respectively disposed on both sides of the shaft axis. There is an advantage that fluctuations in valve characteristics between cylinders can be suppressed by swinging at the same angle and controlling the swing angle evenly by the variable means.
According to the configuration in which the drive means for driving the camshaft includes a drive shaft that is rotated by the crankshaft of the internal combustion engine, and a motion conversion member that converts the rotational motion of the drive shaft into the swing motion of the camshaft. The camshaft can be swung using the power of
According to the configuration in which the drive shaft includes a drive camshaft and the cam for opening or closing the other valve of the intake valve or the exhaust valve is provided on the drive camshaft, the exhaust camshaft or the intake camshaft is used as the drive shaft. Therefore, there is an advantage that the entire variable valve mechanism can be laid out in the same manner as a normal type valve mechanism without a variable function.

In the variable valve mechanism, the following means can be preferably used .

(3) The motion converting member includes a link, one end of the link is connected to the drive shaft, and the other end of the link is connected to the camshaft. More preferably, one end of one link is connected to a position deviated from the axis of the drive shaft, and the other end of the link is connected to a position deviated from the axis of the camshaft. According to this structure, there exists an advantage which can convert the rotational motion of a drive shaft into the rocking motion of a camshaft using one link.

(4) The variable means includes a variable member that changes the amount of displacement of the link per half rotation of the drive shaft, and an actuator that drives the variable member. Examples of the variable member include a member that rotates and a member that linearly moves. Examples of the actuator include a hydraulic piston, a hydraulic motor, an electric motor, an electromagnetic solenoid, and a piezoelectric element. According to this configuration, there is an advantage that the forward movement stroke and the backward movement stroke of the link can be made equal and the swing angle of the camshaft in both directions can be changed uniformly.

(5) A variable member and an actuator are provided on either one of the camshaft and the drive shaft. According to this configuration, there is an advantage that the conventional control shaft can be eliminated, the installation space for the variable valve mechanism can be further reduced, and the swing angle of the camshaft can be accurately changed near the link.

(7) The cam provided on the camshaft is composed of a first cam assigned to one of the cylinders divided into two groups and a second cam assigned to the other group of cylinders. There is provided an actuator that reciprocally drives a cam shaft provided with a first pausing cam arranged side by side with the first cam and a second pausing cam arranged side by side with the second cam in the axial direction. According to this configuration, in a multi-cylinder internal combustion engine, valve characteristics such as switching a cam that opens and closes a valve and a stop cam that does not open and close the valve by an actuator, for example, operating half of the cylinders and stopping the remaining half of the cylinders, etc. There is an advantage that the internal combustion engine can be controlled more variously according to the operation state by adding a cylinder selection function to the variable function.

  According to the variable valve mechanism of the present invention, since the camshaft itself oscillates, parts for oscillating the cam on the camshaft become unnecessary. Therefore, the variable valve mechanism as a whole can be configured in a small and simple manner with a small number of parts, and an excellent effect is achieved in that the valve characteristics can be stabilized by reducing assembly errors.

  Hereinafter, embodiments of 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 an exhaust camshaft 5 and an intake air above a cylinder 3 in an internal combustion engine 2 in which a plurality of cylinders 3 are divided into two banks A and B. And a camshaft 7. The exhaust camshaft 5 is connected to the crankshaft 4 and functions as a drive shaft. An intake cam 15 that opens and closes a plurality of intake valves 17 provided in each cylinder 3 is provided on the intake cam shaft 7 symmetrically with respect to the axis of the intake cam shaft 7.

  As shown in FIG. 2, a single link 8 is interposed between the exhaust camshaft 5 and the intake camshaft 7, and one end of the link 8 is connected to a position deviated from the axis of the exhaust camshaft 5. The other end of the link 8 is connected to a position deviated from the axis of the intake camshaft 7. The exhaust camshaft 5 and the link 8 constitute drive means for swinging the intake camshaft 7 about its own axis. A variable member 23 that changes the amount of displacement of the link 8 per half rotation of the shaft 5 and an actuator 28 that drives the variable member 23 are built in the shaft end of the exhaust camshaft 5. The variable member 23 and the actuator 28 constitute a variable device 29 that changes the swing angle of the intake camshaft 7 according to the operating state of the internal combustion engine 2.

  1 to 6 show Embodiment 1 of the present invention. As shown in FIG. 1, the variable valve mechanism 1 is mounted on a two-bank automobile gasoline engine 2. The engine 2 includes four, six, or eight cylinders 3, of which half of the cylinders 3 are arranged in the first bank A on one side of the crankshaft 4 and the other half of the cylinders 3 are in the second bank B on the opposite side. Is arranged. The cylinders 3 of the first bank A and the cylinders 3 of the second bank B are arranged opposite to each other in a V-shaped posture or a horizontal posture on both sides of the crankshaft 4.

  The variable valve mechanisms 1 of the banks A and B each include an exhaust camshaft 5 above the cylinder 3. The exhaust camshaft 5 is fully rotated in one direction by a crankshaft 4 via a belt (or chain) 6 and functions as a drive shaft of the variable valve mechanism 1. Below the exhaust camshaft 5, an intake camshaft 7 is provided in parallel with the exhaust camshaft 5. The intake camshaft 7 is rocked by the exhaust camshaft 5 through a single link 8 and functions as a driven camshaft of the variable valve mechanism 1.

  As shown in FIGS. 1 and 2, a plurality of exhaust cams 10 are alternately fixed at an angle of 180 ° on the exhaust camshaft 5, and the exhaust valve of each cylinder 3 is rotated as the exhaust camshaft 5 rotates. 13 is opened and closed via the rocker arm 12 according to the cam profile of the exhaust cam 10. A plurality of intake cams 15 are fixed on the intake camshaft 7 symmetrically with respect to the axis of the intake camshaft 7, and the intake valve 17 of each cylinder 3 is connected to the intake cam 15 as the intake camshaft 7 swings. It is opened and closed via the rocker arm 16 according to the cam profile. The rocker arm 16 includes a roller 19 that is supported at the base end by a pivot 18 and engages with the intake cam 15 at an intermediate portion.

  As shown in FIGS. 2 and 3, a pulley 21 (or sprocket) that meshes with the belt 6 is fixed to one shaft end of the exhaust camshaft 5, and a cavity 22 is formed at an eccentric position of the pulley 21. A cup-shaped variable member 23 is rotatably accommodated in the cavity 22, and a pin 24 projects from an end surface of the variable member 23 so as to be positioned on a circumference C passing through the axis O of the exhaust camshaft 5. Yes. A shaft end member 25 is fixed to one end of the intake camshaft 7, and a pin 26 projects from an eccentric position of the shaft end member 25. The link 8 includes an input end 8a connected to the pin 24 on the exhaust camshaft 5 side and an output end 8b connected to the pin 26 on the intake camshaft 7 side, and the rotational motion of the exhaust camshaft 5 is controlled by the intake cam. This is converted into a swinging motion of the shaft 7.

  In the cavity 22, a piston 28 as an actuator is housed side by side with the variable member 23, and the variable member 23 and the piston 28 constitute a variable device 29. The cavity 22 is connected to a hydraulic controller (not shown) via an oil passage on the exhaust camshaft 5, and the stroke of the piston 28 is controlled by the hydraulic controller according to the operating state of the engine 2. The variable member 23 and the piston 28 are formed with inclined splines 23a and 28a, respectively, and the variable member 23 is rotated at an angle corresponding to the stroke of the piston 28 by the engagement of the splines 23a and 28a. The variable member 23 adjusts the position of the input end 8 a of the link 8 via the pin 24 to change the stroke of the link 8 per half rotation of the exhaust camshaft 5.

  Next, the operation of the variable valve mechanism 1 will be described with reference to FIGS. FIG. 3 shows a state when the exhaust cam 10 fully opens the exhaust valve 13 of the cylinder 3. At this time, the variable member 23 of the variable device 29 has the pin 24 arranged at a position coincident with the axis O of the exhaust camshaft 5. Therefore, even if the exhaust camshaft 5 rotates, the link 8 does not move, the intake camshaft 7 and the rocker arm 16 both stop, and the intake valve 17 is held in the closed position.

  FIG. 4 shows a state where the intake valve 17 is opened and closed with a small lift amount when the engine 2 rotates at a low speed. At this time, the variable device 29 rotates the variable member 23 at a small angle, and the pin 24 is disposed at a position slightly away from the axis O of the exhaust camshaft 5. In this state, as shown in FIG. 4A, when the exhaust camshaft 5 rotates halfway, the link 8 moves forward to the intake camshaft 7 side with a small stroke. Then, the intake camshaft 7 swings slightly in the clockwise direction, and the intake cam 15 on one side opens the intake valve 17 through the rocker arm 16 with a small lift amount.

  As shown in FIG. 4B, when the exhaust camshaft 5 continues to make a half rotation, the link 8 moves backward to the exhaust camshaft 5 side with the same stroke as that during forward movement. Then, the intake camshaft 7 slightly swings counterclockwise, and the intake cam 15 on the opposite side opens the intake valve 17 through the rocker arm 16 with a small lift amount. Therefore, as shown by the curve (A) in FIG. 6, both the lift amount and the operating angle of the intake valve 17 are reduced, and the opening timing is controlled late and the closing timing is controlled early. The curve (e) in FIG. 6 shows the lift amount and operating angle of the exhaust valve 13.

  FIG. 5 shows a state where the intake valve 17 is opened and closed with a large lift amount when the engine 2 rotates at high speed. Here, the variable device 29 rotates the variable member 23 at a large angle, and the pin 24 is arranged at a position far from the axis O of the exhaust camshaft 5. In this state, as shown in FIG. 5A, when the exhaust camshaft 5 rotates halfway, the link 8 moves forward with a large stroke. The intake camshaft 7 swings in a clockwise direction at a large angle, and the intake cam 15 on one side opens the intake valve 17 via the rocker arm 16 with a large lift amount.

  As shown in FIG. 5B, when the exhaust camshaft 5 continues to make a half rotation, the link 8 moves backward with the same stroke as that during forward movement. Then, the intake camshaft 7 swings counterclockwise at a large angle, and the intake cam 15 on the opposite side opens the intake valve 17 through the rocker arm 16 with a large lift amount. For this reason, as shown by the curve (b) in FIG. 6, both the lift amount and the operating angle of the intake valve 17 are increased, and the opening timing is controlled early and the closing timing is controlled late. Therefore, by changing the stroke of the link 8 by the variable device 29, the characteristics of the intake valve 17 can be accurately controlled to an arbitrary intermediate value as shown by the curves (c) and (d) of FIG. .

  7 and 8 show a second embodiment of the present invention. The variable valve mechanism 31 includes a pause cam on the intake camshaft 7 so that two groups of cylinders can be driven alternately in an in-line 3, 4-cylinder or V-6, 8-cylinder automotive gasoline engine. It is configured. The configuration of the exhaust camshaft 5, the configuration for swinging the intake camshaft 7, and the configuration for changing the swing angle of the intake camshaft 7 are the same as those in the first embodiment.

  In the cylinder arrangement example shown in FIG. 7, the intake cam 15 that opens and closes the intake valves 17 of the # 1 and # 3 cylinders and the intake cam that opens and closes the intake valves 17 of the # 2 and # 4 cylinders on the intake camshaft 7. 15 are arranged symmetrically with respect to the axial center of the intake camshaft 7. Two intake valves 17 are provided for each cylinder, and the rocker arm 16 is formed in a T shape so that the two intake valves 17 can be opened and closed simultaneously.

  Further, on the intake camshaft 7, the same number of circular idle cams 32a to 32d as the cylinders are fixed. Pause cams 32 a and 32 b for pausing # 1 cylinder and # 2 cylinder are arranged in parallel with intake cam 15 on one side in the axial direction of intake camshaft 7. Stop cams 32c and 32d for stopping the # 3 cylinder and the # 4 cylinder are arranged in parallel with the intake cam 15 on the opposite side of the intake cam shaft 7 in the axial direction. The shaft end member 25 of the intake camshaft 7 incorporates a hydraulic or electric actuator 33 that reciprocates the intake camshaft 7 in the axial direction.

  The actuator 33 is controlled by the controller of the engine 2 to execute one stroke per one rotation of the variable member 23 (one rotation of the exhaust camshaft 7), and the intake cam 15 and the pause cams 32a to 32d are alternately provided to the rocker arm 16. Position to. Therefore, as shown in FIG. 7 (a), when the intake camshaft 7 is driven in the direction of arrow F, the # 3 and # 4 cylinders are held in a rest state, and the intake valves of the # 1 and # 2 cylinders are held. 17 is opened and closed. Also, as shown in FIG. 7B, when the intake camshaft 7 is driven in the direction of arrow R, the # 1 and # 2 cylinders are held in a deactivated state, and the # 3 and # 4 cylinder intake valves 17 is opened and closed.

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) In the variable device 29 of FIG. 2, the variable member 23 and the piston 28 are built in the shaft end member 25 of the intake camshaft 7.
(2) The intake camshaft is used as a drive shaft, the exhaust camshaft is rocked by the intake camshaft via a link, and the rocking angle of the exhaust cam is changed according to the engine operating state by a variable device.

It is a general view of the variable valve mechanism which shows Example 1 of this invention. It is a perspective view which shows the structure of an exhaust camshaft and an intake camshaft in the variable valve mechanism of Example 1. FIG. It is a mechanism figure which shows an effect | action when opening and closing an exhaust valve in the variable valve mechanism of Example 1. FIG. It is a mechanism figure which shows an effect | action when opening and closing an intake valve by small lift amount in the variable valve mechanism of Example 1. FIG. It is a mechanism figure which shows an effect | action when opening and closing an intake valve with a big lift amount in the variable valve mechanism of Example 1. FIG. It is a characteristic view which shows the relationship between a valve lift amount and a working angle. It is a top view of the variable valve mechanism which shows Example 2 of this invention. It is a perspective view which shows the structure of an exhaust camshaft and an intake camshaft in the variable valve mechanism of Example 2. FIG. It is sectional drawing which shows the conventional variable valve mechanism.

Explanation of symbols

1 Variable valve mechanism (Example 1)
2 Engine 3 Cylinder 4 Crankshaft 5 Exhaust Camshaft 7 Intake Camshaft 8 Link 10 Exhaust Cam 13 Exhaust Valve 15 Intake Cam 17 Intake Valve 23 Variable Member 28 Piston 29 Variable Device 31 Variable Valve Mechanism (Embodiment 2)
32 Pause cam 33 Actuator

Claims (5)

In an internal combustion engine in which a plurality of cylinders are arranged, a camshaft having a cam that opens and closes either an intake valve or an exhaust valve provided in each cylinder, and the camshaft are swung around the axis of the shaft. Drive means for moving, and variable means for changing the swing angle, which is the swing amount of the camshaft, according to the operating state of the internal combustion engine,
A plurality of cams are equally provided on the camshaft so as to have the same swing angle on both sides of the swing direction with respect to the shaft center ,
The drive means includes a drive shaft that is rotated by a crankshaft of an internal combustion engine, and a motion conversion member that converts a rotational motion of the drive shaft into a swing motion of a camshaft,
A variable valve mechanism, wherein the drive shaft includes a drive camshaft, and a cam that opens and closes either the intake valve or the exhaust valve is provided on the drive camshaft.   The variable valve mechanism according to claim 1, wherein the motion conversion member includes a link, one end of the link is connected to a drive shaft, and the other end of the link is connected to a camshaft.   The variable valve mechanism according to claim 2, wherein the variable means includes a variable member that changes a displacement amount of the link per half rotation of the drive shaft, and an actuator that drives the variable member.   The variable valve mechanism according to claim 3, wherein the variable member and the actuator are provided at either one of a cam shaft and a drive shaft. The cams provided on the camshaft are a first cam assigned to one group of cylinders in which the plurality of cylinders are divided into two groups and a second cam assigned to the other group of cylinders. ,
The actuator which reciprocates and drives the said camshaft to an axial direction provided with the 1st pausing cam arranged in parallel with the said 1st cam and the 2nd pausing cam arranged in parallel with the said 2nd cam was provided. 5. The variable valve mechanism according to any one of 4 above.

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