JP2009264199A - Variable valve gear - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow smooth coupling by preventing the coupling pin from being caught when coupling a pair of rocker arms in a variable valve mechanism with a coupling pin. <P>SOLUTION: Pin holes 44a, 45a are respectively formed in a pair of rocker arms 33, 34 arranged so as to be adjacent to each other to drive engine valves 16 to a valve opening direction. By slidably fitting a coupling pin 47 of a switching mechanism 41 to the pin holes 44a, 45a, a pair of rocker arms 33, 34 are coupled to and separated from each other to change valve lift and valve timing of the engine valve 16. A plurality of convex parts 42c are formed on a circumferential surface of a cam 42 abutting on at least one of a pair of rocker arms 33, 34 so that the coupling pin 47 can be surely fitted into the pin hole 44a by forcing the rocker arm 33 to abut on the convex part 42c to be vibrated even though axial lines of the pin holes 44a, 45a in a pair of rocker arms 33, 34 do not perfectly coincide with each other. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention contacts an engine valve that opens and closes a combustion chamber of an internal combustion engine, a pair of rocker arms that are arranged adjacent to each other and drives the engine valve in a valve opening direction, and the pair of rocker arms, respectively. A camshaft having a plurality of cams, and a switching mechanism for connecting and separating the pair of rocker arms by slidably fitting a connection pin to a pin hole formed in the pair of rocker arms. The present invention relates to a variable valve gear provided.

  Such a variable valve operating device is known, for example, from Patent Document 1 below.

In this variable valve operating apparatus, a pair of juxtaposed rocker arms are brought into contact with a low-speed intake cam and a high-speed intake cam of a camshaft, respectively, and the pair of rocker arms are connected and separated from each other inside the rocker arm. This is achieved by a connecting pin that is slidably fitted into a pin hole formed in the above.
JP 2007-92726 A

  By the way, the pair of rocker arms is coupled by the coupling pin by moving the coupling pin housed in the pin hole of one rocker arm by hydraulic pressure or a spring and fitting it in the pin hole of the other rocker arm. In this case, the tip of the connecting pin is caught in the opening of the pin hole of the other rocker arm, and the pair of rocker arms may not be connected smoothly.

  The present invention has been made in view of the above circumstances, and when connecting a pair of rocker arms of a variable valve operating apparatus with a connection pin, the connection pin is prevented from being caught and a smooth connection is made possible. Objective.

  In order to achieve the above object, according to the first aspect of the present invention, the engine valve that opens and closes the combustion chamber of the internal combustion engine and the engine valve disposed adjacent to each other are driven in the valve opening direction. And a pair of rocker arms, a camshaft formed with a plurality of cams that respectively contact the pair of rocker arms, and a pin hole formed in the pair of rocker arms to slidably fit a connecting pin. Thus, in the variable valve operating apparatus including the switching mechanism for connecting and separating the pair of rocker arms, a convex portion or a concave portion is formed on the circumferential surface of the cam that contacts at least one of the pair of rocker arms. A variable valve gear characterized by the above is proposed.

  According to a second aspect of the present invention, in addition to the configuration of the first aspect, the convex portion or the concave portion is formed on a peripheral surface of a base circle portion of the cam. A valve device is proposed.

  According to the invention described in claim 3, in addition to the configuration of claim 2, the convex portion or the concave portion is used for measuring the tappet clearance inserted between the base circle portion of the cam and the rocker arm. A variable valve operating device is proposed which is formed so as not to interfere with the gap gauge.

  The intake valve 16 of the embodiment corresponds to the engine valve of the present invention, the intake camshaft 24 of the embodiment corresponds to the camshaft of the present invention, and the low-speed intake rocker arm 33 and the high-speed intake rocker arm 33 of the embodiment. The intake rocker arm 34 corresponds to the rocker arm of the present invention, the low-speed intake cam 42 and the high-speed intake cam 43 of the embodiment correspond to the cam of the present invention, and the first and second connecting pins 46 of the embodiment. 47 correspond to the connecting pins of the present invention.

  According to the configuration of the first aspect, the pin holes are respectively formed in the pair of rocker arms that are arranged adjacent to each other and drive the engine valve in the valve opening direction, and the connection pins of the switching mechanism are provided in these pin holes. By slidably fitting, a pair of rocker arms can be connected and separated to change the valve lift and valve timing of the engine valve. At this time, since the convex portion or the concave portion is formed on the circumferential surface of the cam that abuts at least one of the pair of rocker arms, the rocker arms are not affected by the above-mentioned even if the axis of the pin holes of the pair of rocker arms are not completely aligned. The contact pin can be securely fitted into the pin hole by vibrating in contact with the convex portion or the concave portion.

  According to the second aspect of the present invention, since the convex portion or concave portion of the cam is formed on the peripheral surface of the base circle portion of the cam, the function of the convex portion or concave portion is effectively performed at a position where the phases of the pair of rocker arms are easily aligned. This makes it possible to more smoothly fit the connecting pin into the pin hole.

  According to the third aspect of the present invention, the convex portion or the concave portion formed on the peripheral surface of the base circle portion of the cam does not interfere with the gap gauge for measuring the tappet clearance inserted between the peripheral surface and the rocker arm. Therefore, it is possible to avoid a situation where the gap gauge interferes with the convex portion or the concave portion and measurement of the tappet clearance becomes impossible.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1 to 9 show a first embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a cylinder head portion of an engine, FIG. 2 is a view taken along line 2-2 in FIG. 1, and FIG. 2 is a sectional view taken along line 3-3 in FIG. 2, FIG. 4 is a sectional view taken along line 4-4 in FIG. 2, FIG. 5 is a sectional view taken along line 5-5 in FIG. 7 is an operation explanatory diagram corresponding to FIG. 6, FIG. 8 is an operation explanatory diagram at the time of switching the valve lift, and FIG. 9 is an operation explanatory diagram at the time of measuring the tappet clearance.

  As shown in FIGS. 1 and 2, a cylinder head 12 is coupled to the top surface of a cylinder block 11 of an internal combustion engine, and a piston 14 is slidably fitted to a cylinder 13 provided in the cylinder block 11. Two intake valve holes 12a, 12a and exhaust valve holes 12b, 12b are opened in the combustion chamber 15 formed on the lower surface of the cylinder head 12 so as to face the top surface of the piston 14, and the intake valve holes 12a, An intake port 12c connected to 12a and an exhaust port 12d connected to exhaust valve holes 12b and 12b are formed inside the cylinder head 12.

  A pair of intake valves 16, 16 that open and close the intake valve holes 12 a, 12 a are slidably supported by valve guides 17, 17 provided in the cylinder head 12, and are urged in a valve closing direction by intake valve springs 18, 18. The A pair of exhaust valves 19 and 19 for opening and closing the exhaust valve holes 12b and 12b are slidably supported by valve guides 20 and 20 provided in the cylinder head 12, and are urged in the valve closing direction by the exhaust valve springs 21 and 21, respectively. Is done.

  An intake camshaft 24 and an exhaust camshaft 25 are rotatably supported between a camshaft holder 22 and a camshaft cap 23 coupled to the top surface of the cylinder head 12. A timing chain 28 is connected to an intake sprocket 26 provided at the shaft end of the intake camshaft 24, an exhaust sprocket 27 provided at the shaft end of the exhaust camshaft 25, and a crank sprocket (not shown) provided at the shaft end of the crankshaft. Are wound, and the intake camshaft 24 and the exhaust camshaft 25 rotate in the same direction at a half rotation number of the crankshaft.

  An intake rocker shaft 30 and an exhaust rocker shaft 31 are fixed to the camshaft holder 22. The intake rocker shaft 30 positioned below the intake camshaft 24 is provided with a low-speed intake rocker arm 33 having an adjustment screw 32, 32 abutting against the stem end of the intake valves 16, 16 at the tip, and the low-speed rocker arm 33. And a high-speed intake high-speed rocker arm 34 adjacent to the oscillating member are swingably supported.

  An exhaust rocker arm 36 having adjustment screws 35 and 35 that abut the stem ends of the exhaust valves 19 and 19 is swingably supported on the exhaust rocker shaft 31 positioned below the exhaust camshaft 25, so that the exhaust When the exhaust cam 37 provided on the camshaft 25 contacts the slipper surface 36a provided on the exhaust rocker arm 36, the exhaust valves 19 and 19 are driven to open and close with the same valve lift and valve timing.

  Next, the structure of the switching mechanism 41 that changes the valve lift and valve timing of the intake valves 16, 16 will be described with reference to FIGS.

  The intake camshaft 24 includes a low-speed intake cam 42 having a low height of a lift portion 42b protruding from the base circle portion 42a, and a high-speed intake cam 43 having a high height of a lift portion 43b protruding from the base circle portion 43a. The low-speed intake cam 42 contacts the slipper surface 33a of the low-speed intake rocker arm 33, and the high-speed intake cam 43 contacts the slipper surface 34a of the high-speed intake rocker arm 34. The tip of the low-speed intake rocker arm 33 is bifurcated, and the pair of adjusting screws 32 and 32 that come into contact with the stem ends of the pair of intake valves 16 and 16 are provided there.

  Collars 44 and 45 are press-fitted into the low-speed intake rocker arm 33 and the high-speed intake rocker arm 34, respectively, and pin holes 44a and 45a that can be aligned coaxially and with the same diameter are formed therein. A cup-shaped first connection pin 46 is slidably fitted into the pin hole 44a on the low-speed intake rocker arm 33 side, and a solid second connection is connected to the pin hole 45a on the high-speed intake rocker arm 34 side. The pin 47 is slidably fitted. A coil spring 48 is contracted between the bottom wall 33 b of the pin hole 44 a of the low-speed intake rocker arm 33 and the first connecting pin 46, and the elastic force of the coil spring 48 causes the first connecting pin 46 to pass through. The second connecting pin 47 biased in contact with the bottom wall 34 b of the high-speed intake rocker arm 34.

  An air vent hole 33 c is formed in the bottom wall 33 b of the low speed intake rocker arm 33, and an oil chamber 49 is formed on the bottom wall 34 b side of the high speed intake rocker arm 34. An oil passage 30a and an oil hole 30b formed inside the intake rocker shaft 30 communicate with the oil chamber 49 via an oil groove 34c and an oil hole 34d formed inside the high-speed intake rocker arm 34.

  A spring seat 34e provided on the lower surface of the high-speed intake rocker arm 34 is urged upward by a lost motion spring 50 provided on the cylinder head 12. The elastic force of the lost motion spring 50 causes the high-speed intake rocker arm 34 to The slipper surface 34 a is pressed against the high-speed intake cam 43.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  As shown in FIGS. 5 and 6, when the oil pressure is not applied to the oil chamber 49 of the high speed intake rocker arm 34, the first connecting pin is caused by the elastic force of the coil spring 48 provided in the low speed intake rocker arm 33. 46 is pressed to the high-speed intake rocker arm 34 side, and the second connecting pin 47 is detached from the pin hole 44a of the low-speed intake rocker arm 33 and retracts into the pin hole 45a of the high-speed intake rocker arm 34. The connection between the low-speed intake rocker arm 33 and the high-speed intake rocker arm 34 is released.

  When the intake camshaft 24 rotates in this state, the low-speed intake rocker arm 33, whose slipper surface 33a is pressed by the low-speed intake cam 42, swings around the intake rocker shaft 30, and a pair of tips provided at the distal ends thereof. By pressing the stem ends of the pair of intake valves 16, 16 with the adjusting screws 32, 32, the pair of intake valves 16, 16 opens and closes at a lift portion 42 b of the low speed intake cam 42 with a low lift amount corresponding to the height. Driven.

  At this time, the high-speed intake rocker arm 34 whose slipper surface 34a is pressed by the high-speed intake cam 43 of the intake camshaft 24 swings around the intake rocker shaft 30 while expanding and contracting the lost motion spring 50. Since the intake rocker arm 34 is separated from the low-speed intake rocker arm 33, the swing of the high-speed intake rocker arm 34 does not affect the opening and closing of the intake valves 16, 16.

  When hydraulic pressure is supplied from the oil passage 30a and the oil hole 30b of the intake rocker shaft 30 to the oil chamber 49 via the oil groove 34c and the oil hole 34d of the high-speed intake rocker arm 34, the first and The second connecting pins 46 and 47 slide toward the low-speed intake rocker arm 33, and the low-speed intake rocker arm is moved by the second connecting pin 47 straddling the two pin holes 44a and 45a as shown in FIG. 33 and the high-speed intake rocker arm 34 are coupled together.

  In this state, the rocking of the high-speed intake rocker arm 34, whose slipper surface 34a is pressed by the high-speed intake cam 43 having a high lift portion 42b, is connected to the low-speed intake rocker arm via the second connecting pin 47. Therefore, the pair of intake valves 16, 16 connected to the low-speed intake rocker arm 33 is driven to open and close by a lift portion 43 b of the high-speed intake cam 43 with a high lift amount corresponding to the height. At this time, the low lift portion 42 b of the low speed intake cam 42 moves away from the slipper surface 33 a of the low speed intake rocker arm 33.

  The base circle portion 42a of the low speed intake cam 42 abuts on the slipper surface 33a of the low speed intake rocker arm 33, and the base circle portion 43a of the high speed intake cam 43 is in contact with the slipper surface 34a of the high speed intake rocker arm 34. When abutting, the pin hole 44a of the low speed intake rocker arm 33 and the pin hole 45a of the high speed intake rocker arm 34 are aligned coaxially, so that oil pressure is supplied to the oil chamber 49 and the second connecting pin 47 is attached. By energizing the low-speed intake rocker arm 33, the tip of the second connecting pin 47 can be fitted from the pin hole 45a of the high-speed intake rocker arm 34 to the pin hole 44a of the low-speed intake rocker arm 33. it can.

  However, in reality, the dimensional error of the base circle portion 42a of the low-speed intake cam 42 and the base circle portion 43a of the high-speed intake cam 43, the low-speed intake rocker arm 33, the high-speed intake rocker arm 34, and their pin holes Due to the dimensional error of 44a and 45a, the tip of the second connecting pin 47 is caught by the open end of the pin hole 44a of the low-speed intake rocker arm 33, and the low-speed intake rocker arm 33 and the high-speed intake rocker arm 34 May not be connected smoothly.

  In order to solve this problem, in the present embodiment, a plurality of convex portions 42c (see FIG. 3) are formed on the base circle portion 42a of the low speed intake cam 42, so that the base circle portion 42a of the low speed intake cam 42 has The low-speed intake rocker arm 33 with which the slipper surface 33a abuts is vibrated by contact with the convex portion 42c, and the tip of the second connection pin 47 that is hooked is inserted into the pin hole 44a of the low-speed intake rocker arm 33. The low-speed intake rocker arm 33 and the high-speed intake rocker arm 34 can be securely fitted to the open end and coupled without delay.

  The tappet clearance when the adjusting screws 32 and 32 are used is generally set to about 10 μm to 200 μm, but the height of the convex portions 42 c... Of the low-speed intake cam 42 should be set smaller than the tappet clearance. Thus, it is possible to prevent the intake valves 16 and 16 from performing an unnecessary lift by the convex portions 42c.

  FIG. 8 shows the operation when the intake valves 16, 16 are switched from the low lift amount state to the high lift amount state. In the area A, the second connecting pin 47 which is going to move toward the connecting position is caught at the position a, and is pushed back to the non-connecting position so that the connection fails. In the subsequent region B, the second connecting pin 47 is once hooked at the position b, but is successfully coupled at the position c by the vibration of the low-speed intake rocker arm 33 by the convex portions 42c. As described above, according to the present embodiment, the second connecting pin 47 is reliably prevented from being continuously hooked, and switching from the low lift amount state to the high lift amount state is prevented. It can be done without delay.

  FIG. 9 explains the action when adjusting the tappet clearance.

  To adjust the tappet clearance, the base circle 42a of the low-speed intake cam 42 faces the slipper surface 33a of the low-speed intake rocker arm 33, and a predetermined thickness is provided between the base circle 42a and the slipper surface 33a. Insert the gap gauge G. Subsequently, the adjusting screws 32 and 32 are tightened and fixed so that the intake valves 16 and 16 are not lifted to a position where the gap gauge G is sandwiched between the base circle portion 42a and the slipper surface 33a. At this time, if the convex portion 42c of the low-speed intake cam 42 comes into contact with the gap gauge G, the tappet clearance cannot be adjusted. Therefore, the interval between the two adjacent convex portions 42c, 42c is set to be somewhat wide, Only the base circle part 42a between the parts 42c and 42c needs to abut the gap gauge G.

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

  In the first embodiment, the low-speed intake cam 42 is provided with the convex portions 42c, while in the second embodiment, the low-speed intake cam 42 is provided with the concave portions 42d. The functions of the concave portions 42d are the same as the functions of the convex portions 42c, and the second connecting pins 47 can be smoothly fitted by applying vibration to the low-speed intake rocker arm 33.

  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 embodiment, the low-speed intake cam 42 is provided with the convex portions 42c... Or the concave portions 42d. However, both the convex portions 42c.

  In the embodiment, the three convex portions 42c... Or the three concave portions 42d... Are provided, but any number including one can be selected as the number of the convex portions 42c. However, the number of the convex portions 42c... Or the concave portions 42d.

  In the embodiment, the convex portion 42c... Or the concave portion 42d... Is provided on the base circular portion 42a of the low speed intake cam 42. However, the lift portion 42b may be provided with the convex portion 42c.

  Further, the structure of the switching mechanism 41 is not limited to that of the embodiment. Therefore, the cam provided with the convex portions 42c... Or the concave portions 42d is not limited to the low speed intake cam 42. The intake cams 42, 43 can be provided with convex portions 42c... Or concave portions 42d.

  In the embodiment, the second connecting pin 47 is fitted into the pin hole 44a by hydraulic pressure, but may be fitted by the spring force of the spring instead of the hydraulic pressure.

  Moreover, it may replace with the adjustment screws 32 and 32 of embodiment, and may provide a hydraulic tappet.

  In the embodiment, the switching mechanism 41 for the intake valves 16 and 16 has been exemplified. However, the present invention can also be applied to the switching mechanism for the exhaust valves 19 and 19.

Longitudinal sectional view of engine cylinder head 2-2 line view of FIG. 3-3 sectional view of FIG. Sectional view along line 4-4 in FIG. Sectional view along line 5-5 in FIG. Sectional view taken along line 6-6 in FIG. Action explanatory diagram corresponding to FIG. Action diagram when switching valve lift Action explanation diagram when measuring tappet clearance The figure corresponding to the said FIG. 3 based on 2nd Embodiment.

Explanation of symbols

15 Combustion chamber 16 Intake valve (engine valve)
24 Intake camshaft (camshaft)
33 Low-speed intake rocker arm (rocker arm)
34 High-speed intake rocker arm (rocker arm)
41 Switching mechanism 42 Low speed intake cam (cam)
42a Base circle part 42c Convex part 42d Concave part 43 High speed intake cam (cam)
44a Pin hole 45a Pin hole 46 First connection pin (connection pin)
47 Second connection pin (connection pin)
G Clearance gauge

Claims (3)

An engine valve (16) for opening and closing the combustion chamber (15) of the internal combustion engine;
A pair of rocker arms (33, 34) arranged adjacent to each other and driving the engine valve (16) in the valve opening direction;
A camshaft (24) formed with a plurality of cams (42, 43) respectively contacting the pair of rocker arms (33, 34);
A pair of rocker arms (33, 34) is slidably fitted into pin holes (44a, 45a) formed in the pair of rocker arms (33, 34). A switching mechanism (41) for connecting and disconnecting;
In a variable valve operating apparatus comprising:
A variable valve operating device characterized in that a convex portion (42c) or a concave portion (42d) is formed on a peripheral surface of the cam (42) contacting at least one of the pair of rocker arms (33, 34).   2. The variable valve operating apparatus according to claim 1, wherein the convex portion (42 c) or the concave portion (42 d) is formed on a peripheral surface of a base circle portion (42 a) of the cam (42).   The convex part (42c) or the concave part (42d) interferes with a gap gauge (G) for measuring a tappet clearance inserted between a base circle part (42a) of the cam (42) and the rocker arm (33). The variable valve operating device according to claim 2, wherein the variable valve operating device is formed so as not to occur.

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