JP2009264200A - 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 formed in a first and second rocker arms 33, 34 respectively driven by a corresponding first and second cams 42, 43. By slidably fitting a coupling pin 47 into the pin holes 44a, 45a, the valve lift and valve timing of an engine valve 16 connected to the first rocker arm 33 can be changed. In this case, the first rocker arm 33 is always brought into intimate contact with the first cam 42 by a hydraulic lash adjuster 29. However, the second rocker arm 34 has play by a clearance β with a lost motion spring 50. Thus, a positional error between the pin holes 44a, 45a is absorbed by the play to fit the coupling pin 47 into the pin holes 44a, 45a when coupling the first and second rocker arms 33, 34 with the coupling pin 47. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention has a first rocker arm that abuts on the engine valve and is urged by a hydro lash adjuster in a direction to abut on the first cam provided on the camshaft, and is disposed adjacent to the first rocker arm. The connecting pin is slid into a second rocker arm urged by a lost motion spring in a direction in contact with the second cam provided on the camshaft, and a pin hole formed in the first and second rocker arms. The present invention relates to a variable valve operating apparatus including a switching mechanism that connects and separates the pair of rocker arms by being movably fitted.

The pair of juxtaposed rocker arms are brought into contact with the low-speed intake cam and the high-speed intake cam of the camshaft, respectively, and the connection and separation of the pair of rocker arms are slid into a pin hole formed inside the rocker arm. A variable valve operating device that changes the valve lift and valve timing of an engine valve by achieving it with a connecting pin that is movably fitted is known from Patent Document 1 below.
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.

  At this time, if one of the rocker arms is in contact with the engine valve via the adjustment bolt, the rocker arm can freely swing within the range of the tappet clearance. Even if it is biased toward the cam by the generated force and cannot swing, it is possible to fit the connecting pins by matching the positions of the pin holes of both rocker arms.

  However, when a hydro lash adjuster is used for one rocker arm instead of the adjustment bolt, the one rocker arm is also urged toward the cam by the resilience of the hydro lash adjuster and the tappet clearance disappears. For this reason, there is no play for matching the positions of the pin holes of both rocker arms, and it may be difficult to fit the connecting pins.

  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 first abutting on the engine valve and the abutting on the first cam provided on the camshaft by the hydro lash adjuster. A first rocker arm, a second rocker arm that is disposed adjacent to the first rocker arm, and is biased by a lost motion spring in a direction in contact with a second cam provided on the camshaft; In the variable valve operating apparatus provided with a switching mechanism for connecting and separating the pair of rocker arms by slidably fitting a connecting pin to a pin hole formed in the second rocker arm. The rocker arm has a predetermined gap between the rocker arm and the lost motion spring when contacting the base circle of the second cam. Variable valve system is proposed to.

  According to the invention described in claim 2, in addition to the configuration of claim 1, the radius of the base circle portion of the first cam is set larger than the radius of the base circle portion of the second cam. There is proposed a variable valve gear characterized by this.

  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 first and second rocker arms of the present invention, respectively, and the low speed intake cam 42 and the high speed intake cam 43 of the embodiment correspond to the first and second cams of the present invention, respectively. The first and second connection pins 46 and 47 in the embodiment correspond to the connection pins of the present invention.

  According to the configuration of the first aspect, the pin holes are formed in the first and second rocker arms which are arranged so as to be adjacent to each other and are respectively driven by the corresponding first and second cams. By slidably fitting the connecting pin of the switching mechanism, the first and second rocker arms can be connected and separated, and the valve lift and valve timing of the engine valve connected to the first rocker arm can be changed. it can. At this time, the first rocker arm is always in close contact with the first cam by the hydro lash adjuster, but the second rocker arm has play due to a gap formed between the lost motion spring and the first pin is connected by the connecting pin. When connecting the 1st and 2nd rocker arms, the position error of those pin holes can be absorbed by the play, and the connecting pins can be smoothly fitted into the pin holes.

  According to the second aspect of the present invention, since the radius of the base circle portion of the first cam is set larger than the radius of the base circle portion of the second cam, the second rocker arm that contacts the second cam on the small diameter side is The first rocker arm that is in contact with the first cam on the large-diameter side is displaced toward the camshaft side. From this state, the second rocker arm is moved to the opposite camshaft side (lost motion spring side) by the gap. While displacing, the pin holes of the first and second rocker arms are matched so that the connecting pin can be reliably fitted into the pin hole.

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

  1 to 8 show an 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. 4 is a sectional view taken along line 4-4 of FIG. 2, FIG. 5 is a sectional view taken along line 5-5 of FIG. 1, FIG. 6 is a sectional view taken along line 6-6 of FIG. FIG. 8 is an operation explanatory diagram corresponding to FIG. 6, and FIG.

  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 includes a low-speed intake rocker arm 33 having a hydro lash adjuster 29, 29 at the tip which contacts the stem ends of the intake valves 16, 16, and the low-speed rocker arm. A high-speed intake high-speed rocker arm 34 adjacent to 33 is 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 hydro lash adjusters 29 and 29 that abut 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.

  As is apparent from FIG. 6, the radius R1 of the base circle portion 42a of the low speed intake cam 42 is set larger than the radius R2 of the base circle portion 43a of the high speed intake cam 43 by α. α is a minute amount of about 0.1 mm to 0.2 mm, for example. With the slipper surface 34a of the high speed intake rocker arm 34 in contact with the base circle 43a of the high speed intake cam 43, there is a gap between the spring seat 34e of the high speed intake rocker arm 34 and the upper end of the lost motion spring 50. A gap β is formed. β is larger than α, and is a minute amount of about 0.2 mm to 0.4 mm, for example. The lost motion spring 50 is accommodated in a cylindrical holder 12e provided in the cylinder head 12, and the upper end of the lost motion spring 50 is locked by locking claws 12f and 12f provided at the upper end of the holder 12e. Thus, the gap β can be kept constant even when the free length of the lost motion spring 50 varies.

  When the low-speed intake rocker arm 33 and the high-speed intake rocker arm 34 are separated, the slipper surface 34a of the high-speed intake rocker arm 34 is not necessarily in contact with the base circle 43a of the high-speed intake cam 43. Floating so as to be movable within the gap β. At this time, if the gap β is large, it causes noise and wear, but if it is about 0.2 mm to 0.4 mm, there is no possibility of causing noise and wear.

  As is apparent from FIG. 3, the hydro lash adjuster 29 includes a plunger 51 slidably fitted into a cylinder hole 33d formed at the tip of the low-speed intake rocker arm 33, and protrudes from the cylinder hole 33d. The lower end of the plunger 51 contacts the stem end of the intake valve 16. An oil chamber 52 is defined between the bottom of the cylinder hole 33d and the upper end of the plunger 51, and the oil chamber 52 and the lower end of the plunger 51 are connected by an oil passage 51a. Inside the oil chamber 52, there are provided a coil spring 53 that urges the plunger 51 in the protruding direction, and a check valve 54 that allows only hydraulic oil to flow from the oil passage 51a side to the oil chamber 52 side.

  As is apparent from FIGS. 3 and 5, the oil passage 30c and the oil hole 30d formed in the intake rocker shaft 30 are connected to the oil passage of the plunger 51 via the oil groove 33e and the oil passage 33f of the low-speed intake rocker arm 33. It communicates with 51a.

  Thus, when a gap is generated between the stem end of the intake valve 16 and the lower end of the plunger 51, the plunger 51 protrudes to extinguish the gap by the elastic force of the coil spring 53, and the check valve 54 opens accordingly. Then, hydraulic oil is supplied to the oil chamber 52. After the plunger 51 thus protrudes and the gap is eliminated, even if a load from the intake valve 16 side tries to retract the plunger 51, the check valve 54 is closed and the plunger 51 is prevented from retracting. The Thus, the tap lash clearance can be maintained almost zero by the hydro lash adjuster 29.

  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 hydro lash adjusters 29, 29, the pair of intake valves 16, 16 has a low lift amount corresponding to the height of the lift portion 42 b of the low speed intake cam 42. It is opened and closed.

  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.

  FIG. 8A shows the case where the radius R1 of the base circle portion 42a of the low-speed intake cam 42 is matched with the radius R2 of the base circle portion 43a of the high-speed intake cam 43, and the gap β is set to zero. Is shown. In this case, the slipper surface 33a of the low-speed intake rocker arm 33 contacts the base circle portion 42a of the low-speed intake cam 42 by the urging force of the hydro lash adjuster 29, and the slipper surface 34a of the high-speed intake rocker arm 34 is lost motion spring. The urging force of 50 is in contact with the base circle 43a of the high speed intake cam 43.

  Therefore, if it is assumed that there is no dimensional error of each component, 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, and the second connecting pin 47 The low-speed intake rocker arm 33 and the high-speed intake rocker arm 34 should be connected without any problem. However, in reality, since there is a dimensional error in each part, 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 misaligned, and the low-speed intake by the second connecting pin 47 It may be difficult to connect the rocker arm 33 and the high-speed intake rocker arm 34.

  In FIG. 8B, the radius R1 of the base circle portion 42a of the low-speed intake cam 42 is set smaller than the radius R2 of the base circle portion 43a of the high-speed intake cam 43 (the dimensions opposite to those in the present embodiment). Relationship), and the gap β is formed. In this case, the high-speed intake rocker arm 34 can move in the direction away from the high-speed intake cam 43 within the range of the gap β, but the pin hole 44a of the low-speed intake rocker arm 33 and the high-speed intake rocker arm are moved by the movement. Since the pin hole 45a of the 34 is further displaced, the low speed intake rocker arm 33 and the high speed intake rocker arm 34 cannot be connected by the second connection pin 47.

  FIG. 8C corresponds to this embodiment, and the radius R1 of the base circle portion 42a of the low speed intake cam 42 is set larger than the radius R2 of the base circle portion 43a of the high speed intake cam 43. And the case where the said clearance gap (beta) is formed is shown. In this case, the high-speed intake rocker arm 34 can move in a direction away from the high-speed intake cam 43 within the range of the gap β, and the pin hole 44a of the low-speed intake rocker arm 33 and the high-speed intake rocker in the course of the movement. Since the pin hole 45a of the arm 34 always matches, the low speed intake rocker arm 33 and the high speed intake rocker arm 34 can be connected by the second connection pin 47.

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

  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 explanatory diagram when connecting rocker arms

Explanation of symbols

16 Intake valve (engine valve)
24 Intake camshaft (camshaft)
29 Hydro Rush Adjuster 33 Low-speed intake rocker arm (first rocker arm)
34 High-speed intake rocker arm (second rocker arm)
41 Switching mechanism 42 Low speed intake cam (first cam)
42a Base circle 43 High speed intake cam (second cam)
43a Base circle 44a Pin hole 45a Pin hole 46 First connection pin (connection pin)
47 Second connection pin (connection pin)
50 Lost motion spring R1 Radius R2 of the base circle of the first cam Radius β of the base circle of the second cam Gap

Claims (2)

A first rocker arm (33) that abuts against the engine valve (16) and is urged by a hydro lash adjuster (29) in a direction to abut against a first cam (42) provided on the camshaft (24);
The second rocker arm is disposed adjacent to the first rocker arm (33) and is urged by a lost motion spring (50) in a direction to contact a second cam (43) provided on the camshaft (24). A rocker arm (34);
A pair of rocker arms (33) is slidably fitted into pin holes (44a, 45a) formed in the first and second rocker arms (33, 34). , 34) and a switching mechanism (41) for connecting and separating;
In a variable valve operating apparatus comprising:
The second rocker arm (34) has a predetermined gap (β) between the second rocker arm (34) and the lost motion spring (50) when contacting the base circle (43a) of the second cam (43). A variable valve operating device.   The radius (R1) of the base circle portion (42a) of the first cam (42) is set larger than the radius (R2) of the base circle portion (43a) of the second cam (43). The variable valve operating apparatus according to claim 1.

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