JP2007332886A - Variable valve gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To widely control valve characteristics in response to an operating condition of an internal combustion engine by switching between both-valve variable control and single valve rest control. <P>SOLUTION: Valve lift quantities of valves 8A, 8B are successively changed by driving a slider with a control shaft 17 and changing relative phase differences of an input arm 14 and output arms 15A, 15B. The slider is divided into two to secure a first slide member 16A which meshes with the input arm 14 and output arm 15A and a second slide member 16B which meshes with the output arm 15B. The first slide member 16A is provided with a clutch key 26. A clutch groove 27 is formed in the second slide member 16B. The slide members 16A, 16B are relatively turnably separated from each other in a low-speed rotation range of an engine, and integrally turnably coupled to each other in a high-speed rotation range. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a variable valve mechanism that changes a valve lift amount of an internal combustion engine.

  Conventionally, in a gasoline engine for automobiles, a variable valve mechanism has been proposed in which the valve lift amount is changed according to the engine speed in order to improve fuel efficiency at low speed and low load and increase output at high speed and high load. ing. For example, Patent Document 1 describes a variable valve mechanism as shown in FIGS.

  The variable valve mechanism 51 includes one input arm 54 and two output arms 55 per cylinder on a support pipe 53, and the input arm 54 is swung by a cam 56 on a camshaft 52, and the output arm 55 Open and close the two valves 58 separately via the rocker arm 57. The input arm 54 and the output arm 55 are engaged with the slider 59 through the splines 60 and 61, the splines 60 and 61 are twisted in opposite directions, and the input arm 54 and the output arm 55 are moved in opposite directions as the slider 59 moves. Swing.

The slider 59 is connected to the control shaft 62 by a connecting pin 63, and one end of the control shaft 62 is connected to the actuator 64. Then, the slider 59 is driven by the control shaft 62, the relative phase difference between the input arm 54 and the output arm 55 is changed by the slider 59, and the lift amount of the two valves 58 is continuously changed according to the engine speed. Control to change (both valves continuous variable control) is performed.
JP 2001-263015 A

  However, according to the conventional variable valve mechanism 51, since the two output arms 55 are engaged with the slider 59 which is an integral part, both the output arms 55 are always the same as the input arm 54 as the slider 59 moves. Swings while maintaining the phase difference. For this reason, the control by the variable valve mechanism 51 is limited only to the two-valve continuous variable control, and it is not possible to perform the control (one-valve stop control) for stopping one of the valves when the internal combustion engine rotates at a low speed.

  An object of the present invention is to provide a variable valve mechanism capable of solving the above-described problems, switching between both-valve continuous variable control and single-valve stop control, and widely controlling valve characteristics according to the operating state of the internal combustion engine. There is.

  In order to solve the above problems, the variable valve mechanism according to the present invention includes an input arm driven by a cam on a camshaft, two output arms that open and close two valves per cylinder, and an output. In a variable valve mechanism that includes a slider that meshes with an arm and an input arm, and a control shaft that drives the slider, and that changes the relative phase difference between the input arm and the output arm with the slider to change the valve lift amount, the slider is controlled by the control shaft. A first slide member that meshes with the input arm and one output arm, and a second slide member that meshes with the other output arm, and transmits power from the first slide member to the second slide member. And a clutch means for intermittently connecting and disconnecting.

  Here, the clutch means intermittently transmits power from the first slide member to the second slide member at a predetermined timing when the rotational speed of the internal combustion engine is switched from the low speed range to the high speed range. Specifically, the clutch means separates the first and second slide members so that they can rotate relative to each other in the low-speed rotation range of the internal combustion engine (the low-speed side stroke section of the control shaft). The first and second slide members are coupled so as to be integrally rotatable in the high-speed stroke section.

  According to the variable valve mechanism of the present invention, since the slider is divided into two slide members, the two slide members are coupled by the clutch means, and the lift amount of the two valves can be controlled at the same time. It is also possible to disconnect one of the valves and deactivate one of the valves. Therefore, the two-valve continuous variable control and the one-valve pause control can be switched at an arbitrary timing, and the amount of air in the cylinder and the mixed airflow can be changed in various ways according to the operating state of the internal combustion engine, and the control range of the valve characteristics Can be expanded more than before.

  In particular, the clutch means separates the slide member in the low-speed rotation range of the internal combustion engine and connects the slide member in the high-speed rotation range, so one-valve pause control is performed during low-speed rotation, generating a swirl in the cylinder and improving fuel economy performance In addition, it is possible to perform continuous variable control of both valves during high-speed rotation, increase the amount of air in the cylinder, and generate high output.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As illustrated in FIGS. 2 and 3, the variable valve mechanism 1 of this embodiment separately opens and closes an input arm 14 driven by a cam 9 on a camshaft 5 and two valves 8 per cylinder. Two output arms 15, a slider 16 that meshes with the output arm 15 and the input arm 14, and a control shaft 17 that drives the slider 16. The slider 16 changes the relative phase difference between the input arm 14 and the output arm 15. The lift amount, the operating angle, and the opening / closing timing of the valve 8 are continuously changed.

  The slider 16 is divided into two in the axial direction of the control shaft 17, and includes a first slide member 16 </ b> A that meshes with the input arm 14 and one output arm 15, and a second slide member 16 </ b> B that meshes with the other output arm 15. Yes. Clutch portions 26 and 27 (see FIG. 7) are provided at relative portions of the first slide member 16A and the second slide member 16B, and the power from the first slide member 16A to the second slide member 16B is provided by the clutch portions 26 and 27. Clutch means for interrupting transmission is configured. The clutch means separates the two slide members 16A and 16B so as to be relatively rotatable in the low speed rotation region of the internal combustion engine, and couples the two slide members 16A and 16B so as to be integrally rotatable in the high speed rotation region. ing.

  Next, an embodiment in which the present invention is embodied in a variable valve mechanism of a four-cylinder gasoline engine for automobiles will be described with reference to FIGS. As shown in FIG. 1, the variable valve mechanism 1 of this embodiment includes a housing 3 above four cylinders 2. A plurality of bearing walls 4 are erected on the housing 3, and an intake camshaft 5, an exhaust camshaft 6, and a support pipe 7 are supported on the bearing wall 4 in parallel. An intake cam 9 for driving the intake valve 8 is provided on the intake camshaft 5, and an exhaust cam 11 for driving the exhaust valve 10 is provided on the exhaust camshaft 6. An arm assembly 12 that transmits the power of the intake cam 9 to the intake valve 8 is provided on the support pipe 7.

  As shown in FIGS. 2 and 3, the arm assembly 12 has two input arms 14 that are swung by the intake cam 9 and two intake valves 8 per cylinder that are opened and closed separately via the rocker arm 13. It comprises an output arm 15 and a slider 16 that meshes with each arm 14, 15. A control shaft 17 is inserted inside the support pipe 7, and a slider 16 is connected to the control shaft 17 via a connecting pin 16. One end of the control shaft 17 is connected to an electric or hydraulic actuator 19 (see FIG. 1), and the actuator 19 reciprocates the control shaft 17 and the slider 16 in the axial direction with a stroke corresponding to the engine speed. The relative phase difference between the input arm 14 and the output arm 15 can be changed according to the position of the slider 16.

  As shown in FIGS. 4 and 5, the slider 16 is divided into two in the axial direction of the control shaft 17, and a cylindrical first slide member 16A shown on the left side of the figure and a cup-shaped second slide member 16B shown on the right side. It consists of and. The first slide member 16A is provided with a spline 20 that meshes with the input arm 14, a spline 21 that meshes with the left output arm 15A, and a sleeve 22 that protrudes toward the second slide member 16B. The second slide member 16 </ b> B is provided with a spline 23 that meshes with the right output arm 15 </ b> B and a fitting hole 24 that fits into the sleeve 22. A spring 25 is interposed between the second slide member 16B and the right output arm 15B, and the second slide member 16B is urged toward the first slide member 16A by the spring force of the spring 25.

  A clutch key 26 protrudes from the sleeve 22 of the first slide member 16A, and a clutch groove 27 that engages with the clutch key 26 is formed in the fitting hole 24 of the second slide member 16B. The first slide member 16A and the second slide member 16B are combined at a predetermined phase around the control shaft 17, and the clutch key 26 and the clutch groove 27 are aligned at the timing when the engine speed is switched from the low speed range to the high speed range. . In the low speed rotation range, as shown in FIGS. 5 and 6B, the clutch key 26 is disengaged from the clutch groove 27, and the power of the intake cam 9 is transmitted from the first slide member 16A to the second slide member 16B. First, the two slide members 16A and 16B are separated so as to be relatively rotatable. On the other hand, in the high-speed rotation region, as shown in FIGS. 7 and 8B, the clutch key 26 is engaged with the clutch groove 27, and the power of the intake cam 9 is transmitted from the first slide member 16A to the second slide member 16B. The two slide members 16A and 16B are coupled so as to be integrally rotatable.

  In the variable valve mechanism 1 having the above-described configuration, when the control shaft 17 moves in the stroke section on the low speed side, as shown in FIGS. 5 and 6A, the input arm 14 depends on the position of the first slide member 16A. And the relative phase difference between the output arm 15A vary within a relatively narrow range. As the intake cam 9 rotates, the lift amount (Low) of the intake valve 8A continuously changes in the low lift range. At this time, the second slide member 16B is pushed by the end face of the clutch key 26 and moves with the same stroke as the first slide member 16A. However, as shown in FIG. 6B, since the clutch groove 27 is disengaged from the clutch key 26, the second slide member 16B rotates idly at an angle corresponding to the twist angle of the spline 23. For this reason, both the output arm 15B and the rocker arm 13 are stationary, and the intake valve 8B is held in a resting state. Therefore, one-valve stop control is performed during low-speed rotation of the engine, swirl can be generated in the cylinder, and fuel efficiency can be improved.

  On the other hand, when the control shaft 17 reaches the boundary position between the low speed section and the high speed section, as shown in FIGS. 7 and 8B, the clutch groove 27 is moved to the clutch key 26 as the second slide member 16B rotates. To match. The second slide member 16B is moved to the first slide member 16A by the urging force of the spring 25, and the clutch groove 27 is engaged with the clutch key 26. In this state, when the control shaft 17 moves in the high-speed stroke section, as shown in FIGS. 8A and 8B, the input arm 14 and the output arms 15A and 15B according to the positions of the slide members 16A and 16B. The relative phase difference between and changes greatly. Therefore, as the intake cam 9 rotates, the two output arms 15A and 15B swing at a large angle, and the lift amounts of the two intake valves 8A and 8B continuously change in the high lift range. Accordingly, the double-valve continuous variable control can be performed during high-speed rotation of the engine, and high output suitable for high-speed rotation can be generated.

  In this embodiment, as shown in FIG. 8, in order to equalize the lift amount (High) and the maximum lift amount (Max) when the clutch key 26 and the clutch groove 27 are engaged with each other in the high speed rotation range of the engine. The cam surface 15b of the output arm 15B on the delayed side is formed with a profile different from the cam surface 15b of the output arm 15A on the preceding side. However, under the design conditions that do not require the lift amounts of the two intake valves 8A and 8B to be equal, the profiles of the cam surfaces 15a and 15b are made equal, and the assembly phase of the output arm 15B is set to the one-valve pause control section. The operation can be carried out with a corresponding angle delayed from the output arm 15A. In addition, the configuration and shape of each part can be changed as appropriate without departing from the spirit of the present invention.

It is a top view of the variable valve mechanism which shows one Example of this invention. It is an elevation view of the variable valve mechanism. It is a perspective view which shows the arm assembly of this variable valve mechanism. It is a perspective view which shows the division | segmentation structure of the slider of this arm assembly. It is sectional drawing which shows the operation state of the arm assembly at the time of low speed rotation. It is operation | movement explanatory drawing of the variable valve mechanism at the time of low speed rotation. It is sectional drawing which shows the operation state of the arm assembly at the time of high speed rotation. It is operation | movement explanatory drawing of the variable valve mechanism at the time of high speed rotation. It is an elevational view showing a conventional variable valve mechanism. It is sectional drawing of this variable valve mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Variable valve mechanism 5 Intake cam shaft 8 Intake valve 9 Intake cam 14 Input arm 15 Output arm 16 Slider 16A First position slide member 16B Second slide member 17 Control shaft 19 Actuator 26 Clutch key 27 Clutch groove

Claims (2)

An input arm driven by a cam on a camshaft, two output arms that individually open and close two valves per cylinder, a slider that meshes with the output arm and the input arm, and a control shaft that drives the slider , In the variable valve mechanism that changes the lift amount of the valve by changing the relative phase difference between the input arm and the output arm with a slider,
The slider is divided in the axial direction of the control shaft, and a first slide member that meshes with the input arm and one output arm and a second slide member that meshes with the other output arm are provided. A variable valve mechanism comprising clutch means for intermittently transmitting power to a member.   The clutch means separates the first and second slide members so as to be relatively rotatable in a low speed rotation region of the internal combustion engine, and couples the first and second slide members so as to be integrally rotatable in a high speed rotation region of the internal combustion engine. The variable valve mechanism according to claim 1.

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