JP2005180402A - Driving device of valve lift variable mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving device of a valve lift variable mechanism capable of providing high maintainability without complicating an engine structure. <P>SOLUTION: This driving device 25 rotatingly drives a control shaft (a crankshaft part 14) of a valve lift variable mechanism 1 arranged between a cam 2 and a rocker arm 4 for transmitting a cam lift to an intake valve 3. The driving device has a torque generating actuator (an electric motor 26) and a motive power converting mechanism 27 for converting torque of the actuator into rotational force of the control shaft, and a casing 28 incorporated with the motive power converting mechanism and joining the actuator to an outside surface. One end of the control shaft projects outward from one side of an engine body, The casing is installed on one side of the engine body (a cylinder head 23) via a freely repetitively attachable-detachable fixing means (a bolt 24). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a drive device for driving a variable valve lift mechanism that is capable of continuously and continuously changing a lift amount of an intake valve provided in a combustion chamber.

  The present applicant has already proposed a valve operating mechanism for an internal combustion engine provided with a variable valve lift that continuously and continuously changes the lift amount (valve opening degree) of the intake valve.

According to the technique disclosed in this document, for example, a fan-shaped worm wheel is rotationally driven by a worm that is rotationally driven by an electric motor, and a lever directly connected to the worm wheel is rotated to change the transmission rate of the cam lift to the intake valve. It is supposed to let you. Drive mechanisms such as worms and worm wheels are directly incorporated in the cylinder head or cylinder block.
JP 2002-364317 A

  According to the technique described in Patent Document 1, since the main part of the drive mechanism is built in the engine body, the structure of the engine becomes complicated, and if the drive mechanism is to be maintained / maintained, the engine body However, there was a drawback that it had to be decomposed to some extent.

  In order to solve such a problem and to provide a drive device for a variable valve lift mechanism that can achieve high maintenance and maintainability without complicating the engine structure, claim 1 of the present invention provides a cam ( 2) and a drive device for rotationally driving the control shaft (crankshaft portion 14) of the variable valve lift mechanism (1) provided between the rocker arm (4) for transmitting the cam lift to the intake valve (3). 25), an actuator for generating a rotational force (electric motor 26), a power conversion mechanism (27) for converting the rotational force of the actuator into the rotational force of the control shaft, and a built-in power conversion mechanism and coupling the actuator to the outer surface The control shaft has one end projecting outward from one side of the engine body, and can be repeatedly attached and detached. Was assumed that (bolts 24) via characterized by comprising to attach the casing on one side of the engine body (cylinder head 23).

  According to a second aspect of the present invention, in addition to the above configuration, an oil sump (34) is provided in a portion surrounding the control shaft in the cylinder head, and the portion of the control shaft submerged in oil communicates with the inside of the casing. An oil passage (axial hole 37 and radial holes 38a and 38b) is provided.

  According to such a configuration of claim 1 of the present invention, since the drive device configured independently is attached to the outside of the engine body, it is not necessary to make the engine body complicated, and only the drive device with respect to the engine body is provided. Can be removed, which can contribute to the improvement of maintenance and maintainability.

  In addition, when mounting a drive unit with a single configuration outside the engine body, an oil passage is provided in the joint surface between the cylinder head and the drive unit for supplying lubricating oil, or casting or machine in the cylinder head is provided. It is common to provide a dedicated oil passage for processing, but this method is cumbersome for processing to form the oil passage, and increases the capacity of the oil pump against the increase in oil amount In addition, an increase in pump friction due to an increase in back pressure in the lubricating oil supply path leads to an engine output loss. According to the configuration of claim 2 of the present invention, the lubricating oil scattered in the head cover and the oil leaking from the bearing portion of the camshaft are collected and supplied by gravity. No energy is required and no power loss is caused by them. Moreover, for example, it is only necessary to form an oil sump in a part of the camshaft holder, and the oil passage can be formed only by a relatively simple drilling process, so that an increase in manufacturing cost can be minimized.

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

  1 and 2 show a basic configuration of a variable valve lift mechanism of an internal combustion engine to which the present invention is applied. The variable valve lift mechanism 1 has one rocker arm 4 that transmits the lift of one intake cam 2 to two intake valves 3 at the same time, and an upper pin 6 and a roller follower 5 at the top of the rocker arm 4. An upper link member 7 and a lower link member 9 having one end connected to a lower portion of the rocker arm 4 with a lower pin 8 are provided.

  The other end of the upper link member 7 is pivotally attached to a rocker arm support shaft 10 supported by a camshaft holder 21 (FIG. 4) fixed on the cylinder head, and the other end of the lower link member 9 is a crank of the crank member 11. It is pivotally attached to the pin portion 12.

  Both ends of the crankshaft portion 14 (control shaft) connected to the crankpin portion 12 of the crank member 11 via the crank web portions 13a and 13b are pivotally attached to bearing holes 15 formed in the camshaft holder 21. . The intermediate portion of the crankshaft portion 14 connects the pair of crank web portions 13a and 13b sandwiching the connecting portion between the lower link member 9 and the lower portion of the rocker arm 4 in the variable valve lift device 1 on each cylinder in series. And extending in the cylinder row direction. In FIG. 2, in order to clearly indicate the connecting portion between the lower portion of the rocker arm 4 and the lower link member 9, some concepts such as dividing the crank pin portion 12 and biasing one crank web portion 13 a to the right side. The expression is typical.

  The intake cam 2 is integrally formed with a cam shaft 16 that rotates in synchronization with the crankshaft of the internal combustion engine, and two tappet screws 17 provided at the free ends of the rocker arm 4 abut against the stem ends of the two intake valves 3, With respect to the point that the intake cam 2 presses the roller follower 5 pivotally attached to the rocker arm 4 by the rotation of 16 and thereby the two intake valves 3 are driven to open at the same time, this is different from the known valve operating mechanism of the internal combustion engine. There is no place. The two intake valves 3 are normally urged to be closed by valve springs, but a description of these structures is omitted.

  As shown in FIGS. 3 to 5, the end of the crankshaft portion 14 protruding from the bearing hole 15 of the camshaft holder 21 and passing through the head cover 22 is fixed to the end face in the crankshaft direction of the cylinder head 23 with bolts 24. A driving force is applied from the driving device 25.

  The drive device 25 includes an electric motor 26 (actuator), a power conversion mechanism 27 that converts the rotational force of the electric motor 26 into the rotational force of the crankshaft portion 14, and a casing 28 that incorporates the power conversion mechanism 27 and is coupled to the electric motor 26. It is made up of. The end surface in the crankshaft direction of the casing 28 is open and is liquid-tightly closed by a lid member 29 that can be repeatedly attached and detached.

  The power conversion mechanism 27 incorporated in the casing 28 includes a screw shaft 31 that is rotationally driven by the electric motor 26, a nut member 32 that is screwed to the screw shaft 31, and a connection link 33 that is pin-connected to the nut member 32 at one end. The connecting link 33 is composed of a control arm 34 whose lower end is pin-coupled to the other end of the connecting link 33, and the crankshaft portion 14 that penetrates the bottom wall of the casing 29 into the casing 29 at the upper end of the control arm 34. The terminals are firmly connected. A rotation angle detector 35 is connected to the control arm 34.

  An oil sump 36 that surrounds the crankshaft portion 14 protruding from the bearing hole 15 is formed on the axial end surface of the camshaft holder 21 that is bolted to the upper surface of the cylinder head 22.

  The crankshaft portion 14 is formed with an oil passage composed of an axial hole 37 and radial holes 38a and 38b, whereby the oil sump 36 and the casing 28 of the drive unit 25 are communicated with each other. Yes.

  As a result, the lubricating oil splashed into the head cover 22 or the lubricating oil leaked from the bearing portion of the camshaft 16 is accumulated in the oil reservoir 36, and the crankshaft portion 14 is immersed under the oil surface, so that it flows from the radial hole 38a. The lubricated oil is dropped into the casing 28 of the driving device 25 through the axial hole 37 and the radial hole 38b, and this lubricates the screwed portion between the screw shaft 31 and the nut member 32. The lubricating oil that has fallen into the casing 28 is returned to the cylinder head 23 through a drain hole 39 formed in the bottom of the casing 28.

  The power conversion mechanism 27 is not limited to the above type. For example, a rack gear may be formed on the upper surface of the nut member 32, and the sector gear meshing with the rack gear may be replaced with the control arm 34. If a backlash removal mechanism that applies this scissor gear is provided, high-precision control without rattling can be expected. Further, if a known ball nut is adopted as the nut member 32, further smoothing and high accuracy of operation can be expected. Moreover, since the direction of the force applied to the tooth surface of the rack gear is constant, it is easier to design the power and torsional strength required for the rotation of the crankshaft portion 14 than a link mechanism in which the magnitude and direction of the force changes depending on the rotation angle. is there.

  Although a worm gear mechanism can be used, the worm gear is disadvantageous in terms of operating resistance and manufacturability. Therefore, if it is not necessary to consider the self-holding function during reverse driving, there are few merits to adopt the worm gear mechanism.

  Next, the operating procedure of this apparatus will be described.

  The crankshaft portion 14 of the crank member 11 is closed when the base circle portion of the intake cam 2 is in sliding contact with the roller follower 5 and the two rocker arms 4 are in the raised position (state shown in FIG. 1), that is, the two intake valves 3 are closed. When in the valve state, it is located coaxially with the lower pin 8 pivotally attached to the lower part of the rocker arm 4.

  When the electric motor 26 is driven from this state, the nut member 32 moves linearly by the rotation of the screw shaft 31, and the control arm 34 connected to the nut member 32 via the connecting link 33 swings. As a result, the crank member 11 swings about the crankshaft portion 14, and the crankpin portion 12 moves on the arc A centering on the crankshaft portion 14, so that the crankpin portion 12 is displaced in the vertical direction. Is given.

  When the motor 26 is driven to retract the nut member 32 from the forward position shown in FIG. 3 and the control arm 34 is swung counterclockwise in FIG. 3, the crank member 11 connected to the control arm 34 is counterclockwise. The crankpin portion 12 of the crank member 11 is displaced upward as shown in FIG. Thereby, the shape of the four-bar link connecting the rocker arm support shaft 10, the upper pin 6, the lower pin 8, and the crank pin portion 12 becomes a substantially triangular shape having a vertex on the rocker arm support shaft 10 side. When the intake cam 2 presses the roller follower 5 in this state, the four-bar link is deformed, and the rocker arm 4 swings greatly from the position indicated by the imaginary line to the position indicated by the solid line, and the tappet screw 17 is moved to the stem of the intake valve 3. The end is pressed and opened with a high valve lift HL.

  When the motor 26 is driven to return the nut member 32 to the forward position shown in FIG. 3, the crank member 11 connected to the control arm 34 rotates clockwise, as shown in FIG. 6B. 11 crankpin portions 12 are displaced downward. As a result, the shape of the four-bar link connecting the rocker arm support shaft 10, the upper pin 6, the lower pin 8, and the crankpin portion 12 becomes a substantially triangular shape having a vertex on the tappet screw 17 side. When the intake cam 2 presses the roller follower 5 in this state, the four-bar link is deformed and the rocker arm 4 is slightly swung from the position indicated by the imaginary line to the position indicated by the solid line, and the tappet screw 17 is connected to the intake valve 3. The stem end is pressed and opened with a low valve lift LL.

  In this way, according to the variable valve lift mechanism 1 according to the present invention, the position of the other end (crank pin portion 12) of the lower link member 9 is moved continuously and continuously, as shown in FIG. Between the lift amount at the time of high lift (corresponding to FIG. 6a) and the lift amount at the time of low lift (corresponding to FIG. 6b), the valve timing remains constant and only the lift amount is steplessly Can be changed continuously.

FIG. 5 is a side view showing a part of the variable valve lift mechanism. It is a perspective view which cuts and shows a part of valve lift variable mechanism. It is a front view of a drive device. It is an axial direction end view which shows a camshaft holder partly cut away. It is sectional drawing which follows the VV line in FIG. It is operation | movement explanatory drawing of a valve lift variable mechanism. It is a characteristic line figure of a valve lift.

Explanation of symbols

1 Valve lift variable mechanism
2 Cam 3 Intake valve 4 Rocker arm 14 Crankshaft (control shaft)
23 Cylinder head (engine body)
24 bolts (fixing means that can be repeatedly attached and detached)
25 Drive device 26 Electric motor (actuator for generating rotational force)
27 Power conversion mechanism 28 Casing 34 Oil sump 37 Axial holes 38a and 38b Radial holes

Claims (2)

A drive device for rotationally driving a control shaft of a variable valve lift mechanism provided between a cam and a rocker arm that transmits a cam lift to an intake valve,
An actuator for generating a rotational force, a power conversion mechanism for converting the rotational force of the actuator into the rotational force of the control shaft, and a casing in which the power conversion mechanism is incorporated and the actuator is coupled to an outer surface,
One end of the control shaft protrudes outward from one side of the engine body,
A drive device for a variable valve lift mechanism, wherein the casing is attached to one side of the engine body through a fixing means that can be repeatedly attached and detached.   The oil sump is provided in a portion of the cylinder head that surrounds the control shaft, and an oil passage communicating with the inside of the casing is provided in a portion of the control shaft that is submerged in oil. Drive device for variable valve lift.

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