JP2005140026A - Engine valve system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine valve system with a roller movably supported on a rocker arm for abutting on a cam, preventing the generation of noises due to the movement of a rotating shaft of the roller apart from the rocker arm. <P>SOLUTION: In the engine valve system, the roller 17 supported on the rocker arm 15 rocking with a rocker arm shaft 13 as a supporting point for abutting on the cam 16 is moved via first and second links 18, 20 along the longitudinal direction of the rocker arm 15 with the driving force of an actuator 21 to change a valve lift and a valve timing. At this time, the rotating shaft 17a of the roller 17 is guided to a guide groove 15a of the rocker arm 15, therefore suppressing noises while preventing the movement of the rotating shaft 17a of the roller 17 apart from the guide groove 15a even during high speed operation of an engine. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention includes a camshaft, a cam provided on the camshaft, a rocker arm that opens and closes a valve, a roller that is supported by the rocker arm and abuts against the cam, and moves the roller along the longitudinal direction of the rocker arm. The present invention relates to a valve operating apparatus for an engine including an actuator to be operated.

Such a valve operating apparatus for an engine is known from Patent Document 1 below. According to this valve operating apparatus, the valve lift and the valve timing can be made variable by moving the roller in contact with the cam along the longitudinal direction of the rocker arm.
JP 2001-164911 A

  However, the one described in Patent Document 1 is such that the rotation axis of the roller is guided along an arc-shaped slipper surface provided on the rocker arm. Jumps off the slipper surface of the rocker arm, and there is a possibility of generating noise when the rotation shaft collides with the slipper surface.

  The present invention has been made in view of the above circumstances, and in a valve operating apparatus for an engine in which a roller abutting on a cam is movably supported by a rocker arm, the rotation shaft of the roller is separated from the rocker arm and generates noise. The purpose is to prevent this.

  To achieve the above object, according to the first aspect of the present invention, a camshaft, a cam provided on the camshaft, a rocker arm for opening and closing a valve, and a cam supported by the rocker arm. In a valve operating apparatus for an engine having a roller that abuts and an actuator that moves the roller along the longitudinal direction of the rocker arm, a guide groove that guides the movement of the rotating shaft that supports the roller is formed in the rocker arm. An engine valve mechanism characterized by the above is proposed.

  According to the invention described in claim 2, in addition to the structure of claim 1, there is proposed an engine valve operating device in which the actuator changes the position of the roller in accordance with the phase of the cam. The

  According to the third aspect of the invention, in addition to the configuration of the first or second aspect, the cam is separated from the roller when the rotation shaft of the roller is at a predetermined position of the guide groove of the rocker arm. An engine valve mechanism characterized by the above is proposed.

  According to the configuration of the first aspect, the valve lift and the valve timing can be changed by moving the roller supported by the rocker arm and contacting the cam along the longitudinal direction of the rocker arm by the actuator. At this time, since the rotating shaft that supports the roller is guided by the guide groove formed in the rocker arm, the rotating shaft of the roller is prevented from being separated from the guide groove even during high-speed operation of the engine, thereby suppressing noise. it can.

  According to the configuration of the second aspect, since the actuator changes the position of the roller in accordance with the phase of the cam, it is possible to change the valve total opening angle in addition to the valve lift and the valve timing. .

  According to the third aspect of the present invention, when the rotation shaft of the roller is moved to a predetermined position of the guide groove of the rocker arm, the cam is separated from the roller, so that the valve pause can be realized.

  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 5 show a first embodiment of the present invention. FIG. 1 is a front view of a valve operating apparatus for an engine, FIG. 2 is a perspective view of the valve operating apparatus for an engine, and FIG. FIG. 4 is a diagram for explaining the action, FIG. 4 is a diagram for explaining the action at the time of the minimum valve lift, and FIG.

  As shown in FIG. 1 and FIG. 2, a valve operating device that is provided in a cylinder head of a four-cycle DOHC engine and opens and closes a valve 11 (including both an intake valve and an exhaust valve) is driven by the engine crankshaft. A camshaft 12 that is rotationally driven via a chain or a timing belt; a rocker arm 15 that is pivotally supported at one end by a rocker arm shaft 13 and is provided with an adjusting bolt 14 that abuts against the stem end 11a of the valve 11 at the other end; A roller 17 that is movably provided at an intermediate portion of the rocker arm 15 and that abuts against the cam 16 of the camshaft 12; Grooves 15a, 15a and one end fixed to rocker arm shaft 13 A pair of first links 18, 18, and a pair of second links 20, one end of which is pivotally supported by a pin 19 at the other end of the first links 18, 18 and the other end of which supports the rotating shaft 17 a of the roller 17. 20 and an actuator 21 made of, for example, an electric motor for rotating the rocker arm shaft 13 forward and backward. The valve 11 is urged upward (in the valve closing direction) by a valve spring 23 whose upper end is in contact with a retainer 22 fixed to the stem end 11a. Due to the upward biasing force of the valve spring 23, the rocker arm 15 is biased in the direction in which the roller 17 contacts the cam 16.

  The shape of the guide grooves 15a, 15a of the rocker arm 15 is an arc shape, and when the base circle portion 16a of the cam 16 is in contact with the roller 17, the center of the arc coincides with the axis L1 of the cam shaft 12. When the rocker arm shaft 13 is rotated counterclockwise around the axis L2 by the actuator 21, the axis L3 of the pin 19 at the other end of the first links 18, 18 moves to the left in FIG. 1 on an arc centered on the axis L2. Then, the axis L4 of the rotating shaft 17a of the roller 17 supported on the other end of the second links 20, 20 moves in the guide grooves 15a, 15a to the left in FIG.

  As a result, as shown in FIG. 3, even if the axis L4 of the rotating shaft 17a of the roller 17 approaches the axis L2 of the rocker arm shaft 13 and the height of the lift portion 16b of the cam 16 is the same, the rocker arm 15 As the swing angle increases, the valve lift increases.

  On the other hand, when the rocker arm shaft 13 is rotated clockwise around the axis L2 by the actuator 21, the axis L3 of the pin 19 at the other end of the first links 18, 18 is on the right side in FIG. The axis L4 of the rotating shaft 17a of the roller 17 supported by the other ends of the second links 20 and 20 moves in the guide grooves 15a and 15a to the right in FIG.

  As a result, as shown in FIG. 4, even if the axis L4 of the rotating shaft 17a of the roller 17 is separated from the axis L2 of the rocker arm shaft 13 and the height of the lift portion 16b of the cam 16 is the same, the rocker arm 15 And the valve lift is reduced.

  FIG. 5 shows the lift curve of the valve 11 when the camshaft 12 rotates in the direction of the arrow R. The largest valve lift corresponds to the position of the roller 17 in FIG. 3, and the smallest valve lift. Corresponds to the position of the roller 17 in FIG. Since the buffer curve exists even when the valve lift is reduced, there is no possibility that seating noise of the valve 11 will occur. Since the profile of the cam 16 is constant, the valve opening angle α is constant even when the valve lift changes. However, when the roller 17 moves in the direction in which the valve lift decreases (rightward in FIG. 1), the timing at which the cam 16 rotating in the direction of the arrow R contacts the roller 17 is gradually delayed, so that the valve lift decreases. The valve timing changes in the delay direction. Moreover, since the guide grooves 15a and 15a are formed in an arc shape, the distance between the axis L1 of the camshaft 12 and the axis L4 of the roller 17 is constant, and the tappet clearance does not change.

  If the rotation direction of the cam 16 is set in the direction opposite to the arrow R direction, the cam 16 rotates in the direction opposite to the arrow R direction when the roller 17 moves in the direction in which the valve lift decreases (the right direction in FIG. 1). As the valve lift decreases, the valve timing changes in the advancing direction. Therefore, the valve overlap amount of the intake valve and the exhaust valve can be easily controlled by changing the valve timing.

  As described above, the cam 21 is selectively used with a simple structure in which the rocker arm shaft 13 is rotated by the actuator 21 and the position of the roller 17 is moved along the guide grooves 15a and 15a of the rocker arm 15. Without changing the cam profile, the valve lift and valve timing can be changed to obtain an appropriate valve characteristic according to the operating state of the engine.

  Further, since the rotating shaft 17a of the roller 17 is fitted and guided in the guide grooves 15a and 15a of the rocker arm 15, the rotating shaft 17a of the roller 17 does not lift from the rocker arm 15 even during high speed operation of the engine. Therefore, it is possible to prevent the generation of noise due to the collision between the rotating shaft 17a of the roller 17 and the rocker arm 15.

  Next, a second embodiment of the present invention will be described with reference to FIG.

  In the first embodiment, the actuator 21 is driven only when the valve characteristic is changed, and the position of the roller 17 is moved along the guide grooves 15a and 15a of the rocker arm 15. However, in the second embodiment, the rotation of the camshaft 12 is performed. The valve lift curve is changed in various ways by periodically driving the actuator 21 in synchronization with the above. The structure of the valve operating apparatus itself of the second embodiment is the same as that of the first embodiment.

  FIG. 6A shows a case where the valve opening angle is decreased, and the valve lift curve shown by a solid line shows a state where the valve lift of FIG. 1 is medium. Then, by driving the actuator 21 from the position where the valve lift becomes maximum and moving the roller 17 in the reverse direction with respect to the cam 16, the state is changed to the high valve lift state (see the broken line) shown in FIG. . When the roller 17 is moved in the opposite direction with respect to the cam 16, the cam 16 rotating in the direction of arrow R in FIG. 1 moves from the left to the right with respect to the roller 17, whereas the roller 17 is moved to the rocker arm shaft 13. It means to move from right to left so as to approach. As a result, the total opening angle can be reduced by advancing the valve closing timing while keeping the valve lift constant.

  FIG. 6B shows a case where the valve opening angle is increased, and the valve lift curve shown by a solid line shows a state where the valve lift of FIG. 1 is medium. Then, by driving the actuator 21 from the position where the valve lift becomes maximum and moving the roller 17 in the same direction with respect to the cam 16, the state is changed to the low valve lift state (see the broken line) shown in FIG. . Moving the roller 17 in the same direction with respect to the cam 16 means that the cam 16 rotating in the direction of arrow R in FIG. 1 moves from the left to the right with respect to the roller 17, whereas the roller 17 is moved to the rocker arm shaft 13. It means moving from left to right so as to move away from the camera. As a result, the total opening angle can be increased by delaying the valve closing timing while keeping the valve lift constant.

  FIG. 6C shows a case where the valve opening angle is increased while changing the valve lift stepwise, and the valve lift curve shown by a solid line shows a state where the valve lift of FIG. 1 is medium. Then, the actuator 21 is driven from a position where the valve lift is decreasing, and the roller 17 is moved in the same direction with respect to the cam 16, thereby changing to the low valve lift state (see broken line) shown in FIG. is there. As a result, it is possible to increase the total opening angle by delaying the valve closing timing while reducing the valve lift stepwise.

  Next, a third embodiment of the present invention will be described with reference to FIG.

  In the third embodiment, the shape of the guide grooves 15a, 15a of the rocker arm 15 is different from that of the first embodiment, and other structures are the same as those of the first embodiment. That is, the guide grooves 15a, 15a of the third embodiment are curved in the opposite direction (the direction away from the axis L1 of the camshaft 12) at the end close to the adjusting bolt 14. Therefore, when the rocker arm shaft 13 is rotated clockwise by the actuator 21 and the roller 17 is moved from the state of FIG. 7A to the state of FIG. 7B to the right end of the guide grooves 15a and 15a, the cam As the distance from the axis L1 of the shaft 12 to the axis L4 of the roller 17 increases, the lift portion 16a of the cam 16 does not reach the roller 17. Thereby, the valve 11 can be maintained in the closed state, and the valve pause control can be realized with a simple structure. In addition, since the cam 16 is completely idled when the valve is stopped, the friction can be greatly reduced and fuel consumption can be saved.

  If the actuator 21 is periodically driven in synchronization with the rotation of the camshaft 12 to open the intake valve 11 twice during the intake stroke, the amount of intake air is increased without increasing the pumping loss, And the output of the engine E can be increased by lowering the in-cylinder temperature and increasing the knocking toughness.

  Specifically, after the valve 11 is opened in the first half of the upward inclined portion of the lift portion 16b of the cam 16, the roller 17 is decreased in the second half of the upward inclined portion (the direction in which the valve lift is moved away from the rocker arm shaft 13). ) And the valve lift is forcibly set to 0 at the peak position of the lift portion 16 b of the cam 16, thereby realizing the first opening and closing of the valve 11. Subsequently, after opening the valve 11 by moving the roller 17 to the original position in the first half of the downward slope portion of the lift portion 16b of the cam 16, the valve 11 is closed in the second half of the downward slope portion. Thus, the second opening and closing of the valve 11 can be realized.

  Next, a fourth embodiment of the present invention will be described with reference to FIG.

  In the first to third embodiments, the valve operating device for the DOHC engine has been described. In the fourth embodiment, the present invention is applied to driving the intake valve 11 in the valve operating device for the SOHC engine. That is, an intake cam 16 and an exhaust cam 16 'are provided on the camshaft 12 disposed at the center of the cylinder head, and the exhaust cam 16' drives an exhaust valve via a normal rocker arm 15 '.

  On the other hand, in order to drive the intake valve 11, the rocker arm 15 pivotally supported by the rocker arm shaft 13 is guided in a guide groove 15a, 15a formed at one end thereof so that the rotary shaft 17a of the roller 17 is movable. The adjustment bolt 14 provided at the other end contacts the stem end 11 a of the intake valve 11. One end of the pair of second links 20, 20 is pivotally supported by a pin 19 on the other end of the pair of first links 18, 18 having one end fixed to the rocker arm shaft 13. A roller 17 having a rotating shaft 17 a supported at the other end contacts the intake cam 16. The shape of the guide grooves 15a, 15a of the rocker arm 15 is an arc shape centered on the axis L1 of the camshaft 12 when the roller 17 is in contact with the base circle portion of the cam 16. The rocker arm shaft 13 is connected to the actuator 21 and is driven forward and backward.

  Therefore, as shown in FIG. 8A, when the roller 17 is in the middle of the guide grooves 15a and 15a, the distance between the roller 17 and the rocker arm shaft 13 is medium, so that the valve lift is also medium. As shown in FIG. 8B, when the rocker arm shaft 13 is rotated counterclockwise and the roller 17 is moved to the left end of the guide grooves 15a, 15a, the distance between the roller 17 and the rocker arm shaft 13 is increased. When the maximum value is reached, the valve lift becomes minimum. As shown in FIG. 8C, when the rocker arm shaft 13 is rotated clockwise to move the roller 17 to the right end of the guide grooves 15a and 15a, the roller 17 The valve lift is maximized by minimizing the distance between the rocker arm shaft 13 and the rocker arm shaft 13.

  At this time, when the camshaft 12 rotates in the direction of the arrow R, the valve timing changes in the delay direction as the valve lift decreases, and when the camshaft 12 rotates in the direction of the arrow R ′, As the valve lift decreases, the valve timing changes in the advance direction.

  Therefore, the fourth embodiment can achieve the same operation and effect as the first embodiment described above.

  Moreover, the conventional VTC (phase variable device) can be applied only to a DOHC engine in which the intake valve and the exhaust valve are driven by separate camshafts. According to the fourth embodiment, the intake valve is an SOHC engine. Since the valve timing of the exhaust valve can be controlled independently, the valve overlap amount can be easily adjusted.

  Next, a fifth embodiment related to the third embodiment capable of stopping the valve described in FIG. 7 will be described with reference to FIG.

  Prior to that, a time chart of normal four-cycle operation without valve stop will be described with reference to FIG. A first stroke indicated by a circled number indicates a combustion stroke, a second stroke indicates an exhaust stroke, a third stroke indicates an intake stroke, and a fourth stroke indicates a compression stroke. The stroke with the underlined circled number indicates the combustion stroke.

  In the 6-cycle operation shown in FIG. 9, the intake valve repeats two times of opening and one stop, and the exhaust valve repeats two times of opening and one stop. In the first stroke to the sixth stroke, the third stroke is the intake stroke, the fourth stroke is the compression stroke, the fifth stroke is the combustion stroke, the sixth stroke is the exhaust stroke, and the first stroke to the sixth stroke of the subsequent cycle. Then, the first stroke is an intake stroke, the second stroke is a compression stroke, the third stroke is a combustion stroke, and the fourth stroke is an exhaust stroke. The two types of cycles are repeated alternately. As described above, since the cycle in which the fifth stroke becomes the combustion stroke and the cycle in which the third stroke becomes the combustion stroke are alternately repeated, the explosion intervals become unequal intervals.

  This 6-cycle operation is equivalent to performing an empty 4-cycle operation once in which both the intake valve and the exhaust valve are stopped after performing a normal 4-cycle operation twice.

  According to the fifth embodiment, the in-cylinder temperature is lowered because the combustion interval is increased by the amount of idling, and toughness against knocking can be improved.

  The sixth embodiment shown in FIG. 11 relates to an 8-cycle operation using a valve pause.

  In this 8-cycle operation, both the intake valve and the exhaust valve are stopped every other time, and the normal 4-cycle operation and the idle 4-cycle operation in which both the intake valve and the exhaust valve are stopped are alternately performed. The first stroke is the combustion stroke, the second stroke is the exhaust stroke, the third stroke is the intake stroke, and the fourth stroke is the compression stroke.

  Various modifications can be considered for the sixth embodiment. In the embodiment of FIG. 11, the first stroke immediately before the exhaust stroke (second stroke) is the combustion stroke, but the fifth stroke or the seventh stroke not immediately before the exhaust stroke (second stroke) may be the combustion stroke. it can. Two combustion strokes can be provided in one cycle. Specifically, both the fifth stroke and the first stroke before the exhaust stroke (second stroke) are set as the combustion stroke, both the seventh stroke and the first stroke are set as the combustion stroke, the fifth stroke and the first stroke are performed. Both of the seven strokes can be used as a combustion stroke.

  In this way, by setting the stroke not immediately before the exhaust stroke (second stroke) as the combustion stroke, the time during which the exhaust gas stays in the cylinder is lengthened and the high temperature state is maintained, and the HC in the exhaust gas is reduced. Can contribute. When combustion is not performed in the fifth stroke, the air-fuel mixture sucked in the suction stroke (third stroke) is compressed twice in the fourth and eighth strokes, so that the mixture state of the air-fuel mixture is made uniform. This can improve the stability of combustion.

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

  For example, in the second embodiment of FIG. 6, three examples of changing the valve lift and the valve opening angle are shown, but by changing the direction and timing of moving the roller 17 in various ways, the valve lift and the valve opening angle are changed. Various combinations can be changed.

  In the first to third embodiments, the valve operating apparatus of the present invention can be applied only to the intake valve, only the exhaust valve, or both the intake valve and the exhaust valve.

  In the fourth embodiment, the valve gear of the present invention is applied to the intake valve, but it can be applied only to the exhaust valve or to both the intake valve and the exhaust valve.

The front view of the valve operating apparatus of the engine which concerns on 1st Example Perspective view of engine valve gear Action diagram at maximum valve lift Action diagram for minimum valve lift Diagram showing valve lift curve The figure which shows the lift curve of the valve | bulb of the valve operating apparatus of the engine which concerns on 2nd Example. Front view of a valve operating apparatus for an engine according to a third embodiment Front view of the valve gear of the engine according to the fourth embodiment The figure which shows the time chart of 6 cycle operation based on 5th Example The figure which shows the time chart of 8 cycle operation based on 6th Example The figure which shows the time chart of the conventional 4 cycle operation

Explanation of symbols

11 Valve 12 Camshaft 15 Rocker arm 15a Guide groove 16 Cam 17 Roller 17a Rotating shaft 21 Actuator

Claims (3)

A camshaft (12);
A cam (16) provided on the camshaft (12);
A rocker arm (15) for opening and closing the valve (11);
A roller (17) supported by the rocker arm (15) and contacting the cam (16);
An actuator (21) for moving the roller (17) along the longitudinal direction of the rocker arm (15);
In a valve operating system for an engine equipped with
A valve operating apparatus for an engine, wherein a guide groove (15a) for guiding the movement of a rotating shaft (17a) supporting a roller (17) is formed in a rocker arm (15).   The valve operating apparatus for an engine according to claim 1, wherein the actuator (21) changes the position of the roller (17) according to the phase of the cam (16). The cam (16) is separated from the roller (17) when the rotating shaft (17a) of the roller (17) is at a predetermined position of the guide groove (15a) of the rocker arm (15). Or the valve operating apparatus of the engine of Claim 2.

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