JP2008095600A - Valve gear for multiple cylinder internal combustion engine, and assembling method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniformize a valve lift of each engine valve by each rocking cam by reducing an inclination amount of a rocking camshaft in one cylinder, and also to uniformize a valve lift difference between cylinders by adjusting the inclination amount of each rocking camshaft between cylinders. <P>SOLUTION: This valve gear is provided with: a drive shaft 13 rotatively driven by a crankshaft and having a drive cam 15 at its periphery; a rocking cam component 17 having the rocking camshaft 18 journalled to the periphery of the drive shaft through an insertion hole 18a at a predetermined clearance and a pair of rocking cams 19a, 19b per one cylinder provided at the peripheries at both axial ends of the rocking camshaft, and two inlet valves 2a, 2b operated in opening and closing by rocking the pair of rocking cams. The rocking camshaft is selectively assembled per cylinder based on the inside diameter of the insertion hole so that the lift difference between the inlet valves accompanied by the radial inclination of the rocking camshaft to the drive shaft is adjusted between the cylinders. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a valve operating apparatus for a multi-cylinder internal combustion engine capable of controlling the operating state such as the valve lift amount and the operating angle of an engine valve such as an intake valve or an exhaust valve according to the operating state of the engine. Of a multi-cylinder internal combustion engine and an assembly thereof for reducing the variation between cylinders in the amount of tilting of the swing cam shaft having a plurality of swing cams and making the valve lift amount of the engine valve between the cylinders substantially uniform Regarding the method.

  Various conventional valve operating devices for a multi-cylinder internal combustion engine are provided, and one of them is, for example, one described in Patent Document 1 below.

  The valve operating device includes a drive cam provided on an outer periphery, to which a rotational force of a crankshaft is transmitted, a transmission mechanism that converts the rotational force transmitted from the drive cam into a swinging motion, and the transmission mechanism A pair of swing cams that swings by the rocker arm and opens and closes two intake valves per cylinder via each valve lifter, and the valve lift amount and operating angle of the intake valve are variable according to the engine operating state And a variable lift mechanism.

  In this variable lift mechanism, a control cam is provided for each cylinder on the outer periphery of one control shaft whose rotation is controlled by the control mechanism, and the posture of the transmission mechanism such as the rocker arm is controlled by controlling the rotation of each control cam. By changing it, the valve lift characteristic of each intake valve is changed via each said rocking cam.

Each of the swing cams is integrally provided at both ends in the axial direction of a cylindrical swing cam shaft that is rotatably inserted in the outer periphery of the drive shaft through an internal insertion hole. A cam surface on the lower surface slides on the upper surface of the valve lifter to open and close each intake valve.
JP 2004-60635 A

  By the way, in the valve operating apparatus, the engine performance can be sufficiently enhanced by variably controlling the valve lift amount of the intake valve by the lift variable mechanism. Due to variations in the clearance between the inner peripheral surface of the insertion hole of the swing cam shaft and the outer peripheral surface of the drive shaft, the swing cam shaft may operate in an inclined state on the drive shaft. When operated with such a swing cam shaft tilted, the cam lift amount of each swing cam relative to each valve lifter changes, and the valve lift amount of each intake valve tends to vary. Furthermore, the engine performance deteriorates because the amount of tilting of the swing cam shaft varies between cylinders.

  In particular, during the small valve lift control, the variation in the valve lift amount greatly affects the engine performance.

  The present invention has been devised in view of the technical problem of the conventional valve operating device for a multi-cylinder internal combustion engine. In order to reduce the variation in the tilting amount of the swing camshaft between the cylinders, To provide a valve operating apparatus for a multi-cylinder internal combustion engine and an assembling method thereof capable of making the valve lift difference between two valves of each cylinder uniform by matching the amount of camshaft tilting between the cylinders and preventing deterioration in engine performance. It is aimed.

  The present invention has been devised in view of the actual state of the conventional valve operating device for a multi-cylinder internal combustion engine, and the invention according to claim 1 is a valve operating device for a multi-cylinder internal combustion engine, wherein the crank of the engine A drive shaft that is rotationally driven by a shaft and provided with a drive cam on the outer periphery, and is supported on the outer periphery of the support shaft through a through hole with a predetermined clearance so as to be swingable. A swing cam shaft provided with two swing cams, a pair of engine valves that are opened and closed by swinging the pair of swing cams through the swing cam shaft, and the swing cam A transmission mechanism linked to one end of the shaft in the axial direction and converting the rotational motion of the drive cam into a swing motion and transmitting it to the swing cam; and the tilting of the swing cam shaft relative to the support shaft in the radial direction The difference in lift between the pair of engine valves is made uniform between the cylinders. Is characterized in selectively assembled that the rocking cam shaft for each of the cylinders on the basis of the inner diameter of at least the insertion hole.

  According to the present invention, the tilting amount of the swing cam shaft can be made substantially uniform between the engine valves, thereby reducing the variation between the cylinders in the valve lift difference of the pair of engine valves. Therefore, engine performance and stability can be improved.

  The invention according to claim 2 is a method for assembling a valve operating apparatus for a multi-cylinder internal combustion engine, and in particular, a step of measuring an outer diameter of a support shaft and an inner diameter of an insertion hole of the swing cam shaft; Based on the inner diameter dimension of the insertion hole measured in the measurement step so that the lift difference of each engine valve caused by the tilting of the swing cam shaft with respect to the support shaft is equalized between the cylinders, And an assembling step of selectively assembling the swing cam shaft with respect to the support shaft.

  According to the present invention, the same effect as that attained by the 1st aspect can be attained.

The invention according to claim 3 also relates to an assembling method, and in particular, the step of measuring the outer diameter of the support shaft and the inner diameter of the insertion hole of the swing cam shaft, and the swing cam shaft with respect to the support shaft. Based on the inner diameter dimension of the insertion hole measured in the measurement step, the transmission mechanisms having different lengths are swung so that the lift difference between the pair of engine valves accompanying the tilting in the radial direction of each cylinder is made uniform between the cylinders. An assembly process for selectively assembling to the dynamic camshaft;
It is characterized by having.

  According to a fourth aspect of the present invention, in the method for assembling the valve operating device for the multi-cylinder internal combustion engine according to the third aspect, the tilting between the cylinders of the swing cam shafts is adjusted after the assembling step. Adjusting the lift amount of the engine valve to a predetermined value by the lift adjusting means included in the transmission mechanism, the lift amount of one of the pair of engine valves or the average lift amount or lift position of the lift amount of the pair of engine valves And is further provided.

  According to this invention, the problem that the average lift deviates from the target when the swing cam shaft is selected and the lift difference is adjusted after the average lift amount is first adjusted by the lift adjusting means is eliminated.

  Embodiments of a valve operating apparatus for a multi-cylinder internal combustion engine and an assembling method thereof according to the present invention will be described below in detail with reference to the drawings.

  In this embodiment, the valve operating device is applied to the intake side of a V-type 6-cylinder internal combustion engine, and FIGS. 1 and 2 show a case where it is applied to three cylinders on one bank side. The foremost end) is the first cylinder (NO. 1), the center is the second cylinder (NO. 2), and the left (the last end) is the third cylinder (NO. 3).

  That is, as shown in FIGS. 1, 2, 5, and 6, the valve operating device is slidably provided on the cylinder head 1 via a valve guide (not shown) and is closed by valve springs 3a and 3b. Two intake valves 2a, 2b per cylinder urged in the direction, a variable mechanism 4 for variably controlling the valve lift amount and the operating angle of each intake valve 2a, 2b, and the operating position of the variable mechanism 4 are controlled. A control mechanism 5 for rotating the control mechanism 5 and an actuator 6 for rotationally driving the control mechanism 5.

  The variable mechanism 4 includes a hollow drive shaft 13 rotatably supported by a bearing 14 provided on the upper portion of the cylinder head 1, and one drive cam per cylinder fixed to the drive shaft 13 by a fixing pin. 15 and is supported by the outer peripheral surface of the drive shaft 13 so as to be swingable. The intake valves 2a and 2b are slidably brought into contact with the upper surfaces of the valve lifters 16a and 16b disposed at the upper ends of the intake valves 2a and 2b. The swing cam constituting body 17 that is opened, and a transmission mechanism that is linked between the drive cam 15 and the swing cam constituting body 17 and transmits the rotational force of the drive cam 15 as the swing force of the swing cam constituting body 17. And.

  The drive shaft 13 is formed in a hollow shape inside the engine and is disposed along the longitudinal direction of the engine, and the crankshaft of the engine via a timing chain or the like wound around a driven sprocket 7 provided at one end. The rotational force is transmitted from, and this rotational direction is set in the direction of the arrow in FIG.

  Further, the drive shaft 13 is formed with an oil passage 13a in which lubricating oil is supplied from a main oil gallery (not shown) in the direction of the internal axis.

  As shown in FIG. 5A, the bearing 14 is disposed on the cylinder 1, and a main bracket 14 a that rotatably supports the drive shaft 13 via a swing cam shaft 18 described later, and an upper end portion of the main bracket 14 a. And a sub bracket 14b that rotatably supports a control shaft 32, which will be described later, and both brackets 14a and 14b are fastened together by a pair of bolts 14c and 14c from above.

  In the drive cam 15, the axis Y of the annular cam body is offset from the axis X of the drive shaft 13 in the radial direction by a predetermined amount.

  As shown in FIGS. 1 to 4, the rocking cam structure 17 includes a cylindrical rocking cam shaft 18 that is rotatably inserted and arranged on an outer peripheral surface 13 a of the drive shaft 13 as a support shaft. The swing cam shaft 18 includes a pair of first and second swing cams 19 a and 19 b that are integrally provided at both ends of the swing cam shaft 18 in the axial direction. The drive shaft 13 is swingably supported.

  The swing cam shaft 18 has an insertion hole 18a through which the drive shaft 13 is inserted, and is rotatably supported by the main bracket 14a at a substantially central position in the axial direction of the outer peripheral surface. The journal portion 18b is integrally formed.

  The insertion hole 18a has a first annular groove 20a formed at a substantially central position in the axial direction of the inner peripheral surface, and a pair of second annular grooves 20b on both sides of the first annular groove 20a at a predetermined interval. , 20b are formed.

  The first annular groove 20a has a relatively small width in the axial direction, and is set smaller than the widths of the second annular grooves 20b and 20b. On the other hand, each of the second annular grooves 20b, 20b is formed at a left-right symmetrical position about the axial center line Q of the swing cam shaft 18.

  A pair of first bearing surfaces 21a and 21a are formed on both sides of the inner circumferential surface of the insertion hole 18a with the first annular groove 20a interposed therebetween, and left and right outer sides of the second annular grooves 20b and 20b. That is, a pair of second bearing surfaces 21b and 21b are formed at both axial ends of the insertion hole 18a, respectively, and the second annular groove 20b extends across the first bearing surfaces 21a and 21a. The journal portion 18b is formed at a position avoiding 20b.

  The first and second swing cams 19a and 19b are each formed in the shape of raindrops and have a cam nose portion extending to the tip, and cam surfaces 22a and 22b are formed on the respective lower surfaces.

  The cam surfaces 22a and 22b include a base circle surface on the swing cam shaft 18 side and a lift surface extending in an arc shape from the base circle surface to the cam nose portion, and the lift surfaces are ramps on the base circle surface side. And a head portion connected to the top surface of the maximum lift from the ramp portion to the tip side of the cam nose portion.

  Further, the first swing cam 19a is formed with a pin hole 19c through which a pin 28 for connecting to the other end portion 25b of the link rod 25 described later is inserted on the cam nose portion side of the tip portion. In the front-rear direction of the upper surface, it is formed more firmly than the second swing cam 19b in order to ensure rigidity to receive a large load from the swing force from the link rod 25, the spring force of the valve spring 3, and the like.

  The transmission mechanism includes a rocker arm 23 that is disposed above the drive shaft 13 for each cylinder, a link arm 24 that links each end portion 23a of each rocker arm 23 and each drive cam 15, and a rocker arm 23. The other end 23b of the first and second rocking cams 19a are linked to each other.

  The rocker arm 23 is rotatably supported by a control cam 33 which will be described later through a support hole 23c formed in a cylindrical base portion at the center. Further, a pin 26 protrudes from the one end 23a projecting in one direction from the cylindrical base, while a link is provided to the other end 23b projecting in the other direction of the cylindrical base. A pin hole into which a pin 27 connected to one end of the rod 25 is inserted is formed.

  The link arm 24 includes an annular base 24a having a relatively large diameter and a projecting end 24b projecting at a predetermined position on the outer peripheral surface of the base 24a. The drive cam 15 is located at the center of the base 24a. On the other hand, a fitting hole through which the cam body is rotatably fitted is formed, and a pin hole through which the pin 26 is rotatably inserted is formed in the protruding end 24b.

  The link rod 25 is formed in a substantially square shape having a concave shape on the rocker arm 23 side, and is inserted into each pin hole of the other end portion 23b of the rocker arm 23 and the cam nose portion of the first swing cam 19a at both end portions 25a and 25b. Pin insertion holes through which end portions of the respective pins 27 and 28 are rotatably inserted are formed.

  The control mechanism 5 is provided integrally with the control shaft 32 rotatably supported by the same bearing 14 at the upper position of the drive shaft 13 and the outer peripheral surface of the control shaft 32, and serves as a rocking fulcrum of the rocker arm 23. And a control cam 33.

  The control shaft 32 is disposed in the longitudinal direction of the engine in parallel with the drive shaft 13, and a journal portion at a predetermined position is rotatably supported between the main bracket 14a and the sub bracket 14b of the bearing 14. Yes.

  The control cam 33 is provided for each cylinder, that is, for each rocker arm 23, is formed in a substantially eccentric annular shape, and the position of the axis P2 is deviated from the axis P1 of the control shaft 32 by a predetermined amount. .

  As shown in FIG. 1, the drive mechanism 6 is provided in a housing (not shown) fixed to the rear end of the cylinder head 1, an electric motor 35 fixed to one end of the housing, and the housing. And a ball screw transmission mechanism 36 that transmits the rotational driving force of the electric motor 35 to the control shaft 32.

  The electric motor 35 is constituted by a proportional type DC motor and is driven by a control signal from a control unit 38 for detecting the driving state of the engine.

  The control unit 38 feeds back detection signals from various sensors such as a crank angle sensor 39, an air flow meter 40, a water temperature sensor 41, and a potentiometer 42 for detecting the rotational position of the control shaft 32 to feed the current engine operation. The state is detected by calculation or the like, and a control current is output to the electric motor 35.

  The ball screw transmission mechanism 36 includes a ball screw shaft 43 disposed coaxially with the drive shaft of the electric motor 35 in the housing, and a ball nut 44 that is a moving nut screwed onto the outer periphery of the ball screw shaft 43. The connecting arm 45 is connected to one end of the control shaft 32 along the diametrical direction, and the link member 46 connects the connecting arm 45 and the ball nut 44.

  The ball nut 44 is applied with a moving force in the axial direction while being converted into a linear motion by the rotational motion of the ball screw shaft 43 via each ball.

  Hereinafter, the operation of the present embodiment will be briefly described. First, in the low-rotation operation region including, for example, the idling operation of the engine, the electric motor 35 causes the ball screw shaft 43 to be integrated by the control current from the control unit 38. When rotationally driven in the direction, each ball moves the ball nut 44 linearly in one direction while rolling between the ball circulation groove and the guide groove.

  As a result, as shown in FIGS. 5A and 5B, the control shaft 32 is rotationally driven counterclockwise by the link member 46 and the linkage arm 45, so that the control cam 33 has the same radius around the axis P1 of the control shaft 32. And the thick portion moves away from the drive shaft 13 upward. As a result, the other end 23b of the rocker arm 23 and the pivot point of the link rod 25 move upward with respect to the drive shaft 13, so that the swing cams 19a, 19b are connected to the cam nose via the link rod 25. The part side is forcibly pulled up and the whole is rotated clockwise.

  Therefore, when the drive cam 15 rotates and pushes up the one end portion 23a of the rocker arm 23 via the link arm 24, the lift amount is transmitted to the swing cams 19 and the valve lifters 16a and 16b via the link rod 25. However, the lift amount L1 is sufficiently small.

  Therefore, in the low rotation region of such an engine, the valve lift amount becomes the smallest, so that the opening timing of each intake valve 2 is delayed, and the valve overlap with the exhaust valve is reduced. For this reason, improvement in fuel consumption and stable rotation of the engine can be obtained.

  In addition, when the engine has shifted to the high engine speed range, the electric motor 36 rotates in reverse by a control signal from the control unit 38 to rotate the ball screw shaft 43 in the same direction, so that the ball nut 44 passes through each ball. Move straight in the other direction.

  As a result, the control shaft 32 rotates the control cam 33 clockwise from the position shown in FIGS. 5A and 5B, and rotates the axis P2 downward as shown in FIGS. 6A and 6B. For this reason, the rocker arm 23 is now moved toward the drive shaft 13 and the other end 23b presses the cam nose portion of the swing cam 19a downward via the link rod 25 so that each swing cam The whole 19a, 19b is rotated counterclockwise by a predetermined amount.

  Therefore, when the drive cam 15 rotates and pushes up the one end portion 23a of the rocker arm 23 via the link arm 24, the lift amount is increased via the link rod 25 to the first and second swing cams 19a and 19b and the valve lifter 16a. , 16b, the lift amount is increased.

  Therefore, in such a high rotation region, the valve lift amount L2 of each intake valve 2 is maximized, the opening timing of each intake valve 2 is advanced, and the closing timing is delayed. As a result, the intake charging efficiency is improved and a sufficient output can be secured.

  By the way, during the above-described engine driving, the swing cam shaft 18 is inclined in the radial direction with respect to the drive shaft 13 due to the spring force of the valve springs 3a and 3b and the pressing force of the link rod 25. As a result, there is a problem that a difference occurs in the lift amount of each intake valve 2a, 2b.

  Hereinafter, the cause of the inclination of the swing cam shaft 18 will be described with reference to FIGS. First, the tilting of the swing cam shaft 18 in the low engine speed range will be described with reference to FIG. 3. The link rod 25 is connected to one end of the swing cam shaft 18 via the cam nose portion of the first swing cam 19a. When pushed down by the force of the load FL, the swing cams 19a, 19b open the intake valves 2a, 2b via the valve lifters 16a, 16b. On the other hand, spring loads FS1 and FS2 of the valve springs 3a and 3b simultaneously act on the swing cams 19a and 19b via the valve lifters 16a and 16b.

  The load vector FS1 of the valve spring 3a acting on the first swing cam 19a acts as an upward load substantially along the axial direction of the link rod 25. Therefore, since it overlaps in the direction of the load FL acting from the link rod 25 side, a tilting moment hardly acts on the swing cam shaft 18 by this.

  On the other hand, the spring load FS2 of the valve spring 3b is similarly applied to the second swing cam 19b, but the second swing cam 19b is larger than this because it is separated from the first swing cam 19a by a long distance L. The tilting moment FS2 × L acts counterclockwise.

  Here, the relationship between the valve lift Y1 of the intake valve 2a on one side (link rod side) and the valve lift Y2 of the intake valve 2b on the other side is Y1> Y2, and ΔY = Y1-Y2. This means that the lift ΔY of the intake valve 2a on one side is larger.

  The tilt angle of the swing cam shaft 18 is determined by the clearance ΔD between the inner diameter E (inner peripheral surface) of the insertion hole 18 a of the swing cam shaft 18 and the outer diameter F (outer peripheral surface) of the drive shaft 13. . That is, when the bearing width of the swing cam shaft 18 is S, ΔY≈ΔD × L / S.

  Here, since the inner diameter E of the insertion hole 18a and the outer diameter F of the drive shaft 13 have variations during the manufacturing process, this ΔD varies among the cylinders, and thus ΔY varies among the cylinders. Become. Accordingly, the flow of the air-fuel mixture varies from cylinder to cylinder, and as a result, the combustion state varies, the intake charge efficiency varies from cylinder to cylinder, the engine performance deteriorates, and the rotation becomes unstable.

  Next, the tilting of the swing cam shaft 18 in the engine high rotation range will be described with reference to FIG. 4. In this high rotation range, the spring loads of the valve springs 3a and 3b are applied as loads acting on the swing cams 19a and 19b. The influence of the inertial force FI of the swing cams 19a and 19b is greater than that of FS.

  That is, the swing cam inertia load FI1 acting on the first swing cam 19a acts, and the spring load FS1 of the one side valve spring 3a acts similarly to the case of low rotation. Therefore, although the load of FI1-FS1 acts in a downward direction substantially along the axial direction of the link rod 25, a tilting moment hardly occurs in the swing cam shaft 18.

  On the other hand, the swing cam inertia load FI2 similarly acts on the second swing cam 19b, and the spring load FS2 of the valve spring 3b also acts in the opposite direction.

  Therefore, since the load of FI2-FS2 acts downward and the point of action is separated by a length L, the second swing cam 19b receives a large tilt moment {(FI2-FS2) × L}. . The moment direction is a clockwise direction opposite to that shown in FIG.

  As a result, the swing cam shaft 18 is tilted clockwise, and a lift difference ΔZ between the two intake valves 2a and 2b is generated. Here, the tilt angle is determined by the clearance ΔD between the inner diameter E of the insertion hole 18 a of the swing cam shaft 18 and the outer diameter F of the drive shaft 13. That is, when the bearing width of the swing cam shaft 18 is S, ΔZ≈ΔD × L / S.

  Here, as described above, ΔD is determined by the clearance ΔD between the insertion hole 18a inner diameter E of the swing cam shaft 18 and the outer diameter F of the drive shaft, but the inner diameter E and the outer diameter F have variations in manufacturing processes. This ΔD varies between the cylinders, whereby ΔY in the low rotation range and ΔZ in the high rotation vary between the cylinders. Therefore, similarly, the flow of the air-fuel mixture varies from cylinder to cylinder, combustion varies, and the intake charge efficiency varies from cylinder to cylinder, thereby inviting deterioration in engine performance and unstable rotation.

  Therefore, in this embodiment, the technical problem due to the variation in the lift amount between the intake valves 2a and 2b due to the inclination of the swing cam shaft 18 is solved as follows.

  FIG. 7 shows the lift characteristics of the intake valves 2a and 2b in the first to third cylinders (NO. 1 to NO. 3) of the one side bank, and the bar on the left side in the figure indicates the one side swing cam 19a. The valve lift amount of the intake valve 2a on the side and the bar line on the right side indicate the valve lift amount of the intake valve 2b on the second swing cam 19b side. Further, the upper half of FIG. 7 shows the case in the low engine speed range, and the lower half shows the case in the high engine speed range. In these examples, the rocking cam structure 17 on the third cylinder side is selected. Shows when to do.

  First, an example in which the inclination of the swing cam shaft 18 is large will be described. For example, the clearance E1-F1 at the first cylinder ΔD (ΔD1) is 25 μm, and the second cylinder ΔD (ΔD2) is the clearance. When E2-F2 is 22 μm, the clearance difference between the two is small. The lift difference ΔY between the two intake valves 2a, 2b in the engine low rotation range due to these is, for example, ΔY1 of the first cylinder is 19 μm and ΔY2 of the second cylinder is 17 μm from the equation: ΔY≈ΔD × L / S.

  However, if ΔD3 on the third cylinder side has a clearance E3-F3 of 50 μm and a large clearance, ΔY3 in this case is 38 μm, which is larger than the other cylinders. Therefore, only the third cylinder side has a different combustion state, and when viewed in a multi-cylinder engine, there is a possibility that the engine performance is lowered or the rotation becomes unstable.

  Therefore, when the inner diameter E of the insertion hole 18a of the swing cam shaft 18 is selectively reassembled to the swing cam structural body 17, that is, ΔD1 and ΔD2 are the same and ΔD3 ′, that is, ( When E3′−F3) is reconfigured to be 24 μm (the location of the upper third cylinder in FIG. 7), ΔY3 ′ becomes 18 μm, and the lift amount is substantially equivalent to that of ΔY1 and ΔY2.

  As a result, the variation in lift difference between the intake valves 2a and 2b between the cylinders can be suppressed. As a result, the performance of the multi-cylinder internal combustion engine can be improved and the rotation can be stabilized.

  Next, considering the lift difference between the two valves in the high rotation range, in this high rotation range, as described above, the influence of the inertial force due to the IP of the cam nose portions of the swing cams 19a and 19a is affected by the valve springs 3a and 3b. Therefore, the tilting direction of the swing cam shaft 18 is reversed (see FIG. 4).

  That is, as shown in the position of the first cylinder in FIG. 7, a lift difference ΔZ1 (19 μm) between the intake valves 2a and 2b is generated by ΔD1, which is the difference E1-F1 in the inner and outer diameters on the first cylinder side. The lift of the intake valve 2a on the side of the 1 swing cam 19a is lower. As described above, ΔD2 (22 μm), which is the inner / outer diameter difference E2-F2 on the second cylinder side, is close to ΔD1 (25 μm), which is the innermost / outer diameter difference E1-F1 on the cylinder side. The lift difference ΔZ2 (17 μm) between 2a and 2b is a close value.

  On the third cylinder side, the difference between the inner and outer diameters E3-F3 is excessively large as ΔD3 (50 μm), so the lift difference ΔZ3 between the two valves (intake valves 2a, 2b) is as large as 38 μm.

  Therefore, here, by selectively assembling the rocking cam structure 17 as described above, the lift difference ΔZ3 ′ becomes 18 μm, which is substantially the same lift difference as the first and second cylinders.

  Therefore, if the rocking cam structure 17 (rocking cam shaft 18) is selectively assembled, the lift difference between the two valves can be made uniform between the cylinders in both the low engine speed range and the high engine speed range. .

  Next, considering the engine middle speed range, for example, when the rotational speed is decreased from the high speed range, the inertial force of the cam nose portion decreases. Therefore, as shown in FIG. Receives a moment in the clockwise direction, and gradually rises away from the state where it hits the outer peripheral surface of the drive shaft 13 at the upper right end. That is, as the rotational speed decreases, the swing cam shaft 18 gradually tilts counterclockwise and the tilt angle decreases.

  When the rotation is medium, the swing cam shaft 18 is hardly tilted and becomes almost parallel to the drive shaft 13, and when the rotation speed is further decreased, the camshaft 18 is tilted in the opposite direction. Finally, the state shown in FIG. The swing cam shaft 18 receives a moment in the counterclockwise direction and hits the edge of the outer peripheral surface of the drive shaft 13 at the upper left end.

  Even in this case, if the difference ΔD between the outer diameter F of the drive shaft 13 and the inner diameter E of the insertion hole 18a in each cylinder is the same regardless of the rotation speed, the lift difference between the intake valves 2a and 2b is large between the cylinders. The difference can be suppressed.

  As described above, when configured as in this embodiment, the difference in lift between the intake valves 2a and 2b can be suppressed regardless of the engine speed, and the combustion of a multi-cylinder internal combustion engine can be stabilized. , Engine performance is improved.

  Here, it is conceivable that the target of selective assembly is the drive shaft 13 instead of the rocking cam component 17, but since this is a single shaft, the shaft diameter (outer diameter) F is 3 cylinders. Since the values are relatively stable at the three insertion positions of each swing cam shaft 18, the necessity for selective assembly is low. However, the inner diameter E of the insertion holes 18a of the three swing cam shafts 18 is measured so that the shaft diameters F of the drive shafts 13 at the three insertion positions are respectively equal to ΔD (ΔD1, ΔD2, ΔD3) for the three cylinders. (E1, E2, E3) may be selected.

  In the first annular groove 20a and the second annular grooves 20b, 20b, the lubricating oil that has flowed into the oil passage hole 13a in the drive shaft 13 is formed in an oil hole (not shown) formed in the radial direction of the drive shaft 13. It comes to be supplied through. Therefore, the space (clearance) between the outer peripheral surface of the drive shaft 13 and the inner peripheral surfaces of the bearing portions 21a, 21b, 21b is sufficiently lubricated. Therefore, the irregular behavior of the swing cam shaft 18 due to the friction of the inner peripheral surface hardly occurs, and the lift difference between the two valves is stabilized also in that sense.

  FIG. 8 shows a second embodiment, in which a lift adjusting mechanism 30 is provided in the transmission mechanism in addition to the selective assembly of the rocking cam structure 17 (the rocking cam shaft 18) of the first embodiment. The lift adjusting mechanism 30 has the same structure as that described in Japanese Patent Application Laid-Open No. 2006-105082 previously filed by the present applicant.

  Briefly, the lift adjusting mechanism 30 includes a substantially rectangular block-like linkage portion 31 integrally provided at the tip of the other end portion 23b of the rocker arm 23, and an inner surface from the upper surface in the gravity direction of the linkage portion 31. A fixing female screw hole into which the fixing screw member 32 is screwed from above, and a pin through which the support pin 33 is inserted from both side surfaces of the linkage portion 31 in a direction perpendicular to the female screw hole. An insertion hole, and a shim insertion hole 35 that is formed in the direction perpendicular to the female screw hole and the pin insertion hole in the axial direction of the rocker arm 23 from the front surface side of the linkage portion 31 and in which the adjustment shim 34 is inserted. It is equipped with.

  The length of the adjustment shim 34 is set to be larger than the depth of the shim insertion hole 35, and the adjustment shim 34 is formed so that the front end protruding from the shim insertion hole 35 can be gripped to be easily inserted and removed. . Note that a plurality of adjustment shims 34 having different arc surface depths are prepared in advance.

  In order to adjust the valve lift amount of the intake valves 2 and 2 when assembling each constituent member, first, the optimum adjustment shim 34 is selected and inserted into the shim insertion hole 35 and the support pin 33 and this Then, the fixing screw member 32 is inserted into the fixing female screw hole from the upper side in the direction of gravity and fastened. That is, when the support pin 33 is sandwiched between the adjustment shim and the fixing screw member 32, the position of the shaft fulcrum of the link rod 25 is substantially changed so that the lift amount of each intake valve 2a, 2b can be adjusted. It has become.

  Therefore, according to this embodiment, first, as in the first embodiment, the lift cam component 17 is selectively assembled between the cylinders, and the lift difference between the intake valves 2a, 2b between the cylinders. After the adjustment, the adjustment shim 34 and the like are adjusted so that the average lift Ya in the low rotation range of both the intake valves 2a and 2b in the same cylinder is made uniform among the cylinders. That is, according to the description in FIG. 7, the lift adjustment mechanism 30 first adjusts the average lift values Ya1 and Ya2 of the intake valves 2a and 2b of the second cylinder, and then the average lift value Ya3 ′ of the third cylinder. Adjust to match. The average lift to be combined may be the average lift Ya in the low rotation range or the average lift Za in the high rotation range. That is, the average lift Ya in the low rotation range is a small value because the force by which the link rod 25 is compressed by the spring load of the valve springs 3a and 3b is small, and the average lift Za in the high rotation range is the link rod 25 and the like. However, since the force extended by the inertia load of each cam nose part of rocking cam 19a, 19b is large, it becomes a large value, but either may be used as a reference.

  FIG. 9 is a flowchart showing the procedure of lift adjustment work when assembling each component of this embodiment. First, in step 1, the inner diameter of the insertion hole 18a of the swing cam shaft 18 of each cylinder is shown. The clearance ΔD is measured using a measuring instrument such as a caliper from the equation of the outer diameter F of the E-drive shaft 13.

  Next, in step 2, it is determined whether or not the difference between the cylinders in the clearance ΔD is greater than or equal to a predetermined value. If it is equal to or smaller than the predetermined value, the process proceeds to step 4. .

  In this step 3, in order to adjust the clearance ΔD between the cylinders, at least one cylinder is different in the inner diameter E of the rocking cam structure 17, that is, the insertion hole 18a of the rocking cam shaft 18 as described above. Select and assemble. This reduces the variation between cylinders in the lift difference between the intake valves 2a, 2b.

  Next, in step 4, the average lift Ya of both intake valves 2a, 2b in each cylinder is measured, and in step 5, whether or not the difference (variation) between the cylinders in the average lift Ya is greater than or equal to a predetermined value. Determine.

  Here, if the variation of the average lift Ya among the cylinders is less than or equal to a predetermined value, the engine valve lift on the link rod 25 side substantially matches the engine valve lift on the link rod 25 side in all cylinders. Therefore, the process returns as it is, but if it is determined that the value is equal to or greater than the predetermined value, the process proceeds to step 6.

  In step 6, the lift adjustment mechanism 30 adjusts the average lift of each intake valve 2a, 2b in the specific cylinder where the average lift Ya is large or the specific cylinder where the average lift Ya is small, and the lift amount between all the cylinders is adjusted. End with the absolute value of.

  Therefore, in this embodiment, the absolute value of the average lift Ya between the two valves by the lift adjusting mechanism 30 in addition to the selective assembly of the swing cam constituting body 17, that is, in addition to adjusting the lift difference between the two valves between the cylinders. Since it is possible to match between the cylinders, it is possible to further reduce variations in combustion and intake charge efficiency between the cylinders. In addition, as a lift adjustment means, it is also possible to selectively assemble one having a different distance between the two holes of the link rod 25 without using the lift adjustment mechanism 30.

  FIG. 10 shows a third embodiment. By selectively assembling the oscillating cam structure 17 in the first embodiment, the clearance ΔD between the cylinders is adjusted and the link rod 25 side is intentionally moved. Only the lift amount of one swing cam 19a is increased.

  That is, as described in the lower diagram of FIG. 7, a lift difference between the intake valves 2a and 2b due to the tilting of the swing cam shaft 18 occurs in the high engine speed range, thereby causing the mixture to be mixed in the intake stroke. A swirl is generated, whereby the efficiency of filling fresh air is reduced, or knocking is likely to occur, and the output tends to decrease.

  Therefore, in the present embodiment, the outer shape of the first swing cam 19a in which the lift amount is reduced due to the tilt of the swing cam shaft 18 in the high rotation range is formed large, and the intake valve 2a on one side corresponding thereto is formed. The lift amount is set to be large. Then, as shown in the lower diagram of FIG. 10, in the high rotation range, the difference between the lift due to the clockwise tilt of the swing cam shaft 18 and the increase in the cam lift of the first swing cam 19a causes a gap between the intake valves 2a and 2b. The lift difference is almost eliminated. Accordingly, the generation of the intake swirl in such a high rotation range is sufficiently suppressed, and the above-described technical problem can be eliminated.

  On the other hand, in the engine low speed region, as described above, the tilt of the swing cam shaft 18 is reversed, so that the lift amount increases due to the shape of the first swing cam 19a as shown in the upper diagram of FIG. Then, the lift difference between the two intake valves 2a, 2b becomes large due to the lift difference between the two intake valves 2a, 2b due to the tilting of the swing cam shaft 18 in the counterclockwise direction.

  Therefore, sufficient intake swirl is generated, combustion can be further improved, and fuel consumption and exhaust emission performance can be improved.

  FIG. 11 shows a fourth embodiment. As a measure for slightly increasing the lift amount on the first swing cam 19a side as in the third embodiment, the cam surface 22a of the first swing cam 19a and the first valve are shown. The cam clearance ΔC1 between the upper surface of the lifter 16a is set smaller than the cam clearance ΔC2 between the cam surface 22b of the second swing cam 19b and the upper surface of the second valve lifter 16b.

  Therefore, according to this embodiment, even when the cam profiles of the cam surfaces 22a and 22b of the swing cams 19a and 19b are set to be the same, the valve lift amount on the first swing cam 19a side is slightly increased. It becomes possible to do. Therefore, the same effect as the third embodiment can be obtained.

  FIG. 12 shows a fifth embodiment, in which a lassia adjuster 40 for adjusting the cam clearance between the cam surfaces 22a and 22b of the swing cams 19a and 19b and the valve lifters 16a and 16b to zero is provided. .

  That is, as described in the first to third embodiments, even if the swing cam shaft 18 is tilted between the cylinders, the swing cams 19a and 19b and the valve lifters 16a and 16b If the cam clearance varies, the lift difference between the intake valves 2a, 2b and the average lift vary.

  Therefore, as shown in FIG. 12 (see, for example, JP-A-2003-172113), the cams between the swing cams 19a and 19b and the valve lifters 16a and 16b are provided inside the valve lifters 16a and 16b. A lassia adjuster 35 for adjusting the clearance to zero is provided.

  This eliminates variations in cam clearance between the swing cams 19a, 19b and the valve lifters 16a, 16b. Therefore, the lift difference and average lift accuracy in the first to third embodiments can be reduced. It becomes possible to improve. Thereby, the variation between the cylinders due to the lift difference between the pair of intake valves 2a and 2b can be further reduced.

  The lassia adjuster 35 is provided inside a pivot disposed on one end side of a swing arm interposed between the swing cams 19a and 19b and the stem ends of the intake valves 2a and 2b, for example. It may be a thing. For example, the structure described in Japanese Patent Application Laid-Open No. 2003-155906 may be used.

  As a sixth embodiment, the clearance ΔD between the outer diameter F of the drive shaft 13 and the inner diameter of the insertion hole 18a of the swing cam shaft 18, the cam surfaces 22a and 22b of the swing cams 19a and 19b, and the valve lifters. When the cam clearance (ΔC) between the upper surfaces of 16a and 16b is assumed to be zero, the lift difference (ΔY) between the intake valves 2a and 2b becomes substantially constant regardless of the rotation angle of the control shaft 32. Thus, the cam profiles of the cam surfaces 22a and 22b of the swing cams 19a and 19b were set.

  FIG. 13 shows typical valve lift characteristics of the intake valves 2a and 2b by the swing cams 19a and 19b when the cam profile is set as described above, and the solid line shows the theoretical lift characteristics by the first swing cam 19a. The broken line is the theoretical lift characteristic by the second rocking cam 19b. Here, the theoretical lift characteristic is a theoretical valve lift characteristic based on each cam profile when ΔD and ΔC are assumed to be 0 as described above. The cam profile is set so that the theoretical lift differences Δ1, Δ2 and Δ3 in the respective peak lift regions are substantially the same in any of the minimum lift, the intermediate lift and the maximum lift. .

  Therefore, according to this embodiment, the lift difference between the two intake valves 2a and 2b is substantially constant at Δ1≈Δ2≈Δ3. For this reason, even when the lift amount when ΔD and ΔC are considered, the lift difference between the pair of intake valves 2a and 2b can be maintained regardless of the control lift amount when the control shaft 32 is twisted. A good combustion state can be obtained in any engine operating state.

  FIG. 14 is a diagram illustrating the horizontal axis as the angle of the control shaft 32 and the vertical axis as the valve lift amount. When the control lift is changed by twisting the control shaft 32, the upper solid line indicates the change in the theoretical lift on the link rod 25 side, and the lower broken line indicates the change in the theoretical lift on the anti-link rod 25 side. Here, if Δ1≈Δ2≈Δ3, the same lift difference can be maintained regardless of the control lift amount.

  Further, the cam profiles of the swing cams 19a and 19b are changed so that the peak lift difference Δ1 at the minimum lift is maximized, and the peak lift differences Δ2 and Δ3 at the intermediate lift and the maximum lift are substantially the same. (Δ1> Δ2≈Δ3) can be set, and if set in this way, a sufficient swirl is generated in the low rotation range, combustion is improved, and fuel consumption and exhaust emission performance are improved. When such Δ1 is expressed as Δ1 ′, the one-dot chain line in FIG. 14 corresponds to this.

  Furthermore, if the cam profile is changed so as to satisfy the relationship of Δ1> Δ2> Δ3, swirl can be sufficiently generated even in a steady operation region that is an intermediate lift, and combustion can be improved. is there.

  The present invention is not limited to the configuration of each of the embodiments described above, and the configuration can be arbitrarily changed without changing the technical idea of the invention.

  Furthermore, the present invention can be applied to the exhaust valve side or both valve sides in addition to the intake valve side. Furthermore, the variable mechanism is not necessarily limited to that of the above embodiment. The follower for opening and closing the engine valve may be a bucket type as illustrated or a swing arm type. Of course, the number of cylinders of the internal combustion engine can be applied to multi-cylinders such as four cylinders and in-line six cylinders.

The technical ideas other than the invention described in the claims, as grasped from the embodiment, will be described below.
(A) A valve operating apparatus for a multi-cylinder internal combustion engine according to claim 1, wherein the transmission mechanism is provided with lift adjusting means for simultaneously adjusting the lift amounts of the pair of engine valves.

According to the present invention, the lift difference of the pair of engine valves can be adjusted between the cylinders by selecting the swing cam shaft, and the average lift of the pair of engine valves can be adjusted between the cylinders by the lift adjusting means. it can. Therefore, it is possible to further reduce variations in combustion between cylinders and intake charging efficiency.
(B) After selectively assembling the swing cam shaft and adjusting the tilt of the swing cam shaft in the radial direction between the cylinders to a predetermined value, at least one of the lift amounts of the pair of engine valves 2. A valve operating apparatus for a multi-cylinder internal combustion engine according to claim 1, further comprising a lift adjusting mechanism for adjusting a lift amount or a lift position of the engine valve.
(C) The valve operating apparatus for a multi-cylinder internal combustion engine according to claim 1, wherein the cam lift amount on one side of the pair of swing cams is larger than the cam lift amount on the other side.

According to the present invention, in addition to being able to match the lift difference between the pair of engine valves between the cylinders, the lift difference between the pair of engine valves is increased in the low engine speed range to enhance the swirl flow of the air-fuel mixture. The combustion level itself can be improved, and in the high rotation range, the lift difference between the pair of engine valves can be reduced to reduce the swirl flow of the air-fuel mixture, thereby improving the output.
(D) The valve operating apparatus for a multi-cylinder internal combustion engine according to claim 1, wherein the cam clearance amount on one side of the pair of swing cams is made smaller than the cam clearance amount on the other side.

According to the present invention, as described in (C) above, the valve lift of the engine valve on one end side can be increased without providing a cam lift difference between the pair of swing cams.
(E) A multi-cylinder internal combustion engine according to claim 1, wherein a lash adjuster for adjusting a cam clearance to zero is provided between the pair of swing cams and the pair of engine valves corresponding thereto. Engine valve gear.

The lift difference between the pair of engine valves varies depending on the variation of the cam clearances. However, if a lash adjuster is used, these can be maintained at a constant value or zero. It is possible to further reduce the variation between cylinders due to the above.
(F) The valve operating apparatus for a multi-cylinder internal combustion engine according to claim 1, wherein a support shaft that supports the swing cam shaft so as to be swingable is the drive shaft.

By using the support shaft as the drive shaft, the rotation of the drive shaft stabilizes the lubrication state between this outer peripheral surface and the inner peripheral surface of the insertion hole of the swing cam shaft. The falling behavior is stable. Therefore, the lift difference between the pair of engine valves is stabilized, and variations between the cylinders are reduced.
(G) The operation of the multi-cylinder internal combustion engine according to claim 1, further comprising a control shaft that changes the lift of the pair of engine valves by changing the attitude of the transmission mechanism by rotating. Valve device.

By rotating the control shaft, it is possible to perform variable control of the valve lift amount according to the engine operating state, so that the lift difference between the pair of engine valves is stabilized. As a result, various performances of the engine can be improved and stabilized.
(H) Lift of the pair of engine valves when the clearance between the outer peripheral surface of the support shaft and the inner peripheral surface of the insertion hole of the swing cam shaft and the cam clearance of the swing cam are assumed to be zero, respectively. The multi-cylinder internal combustion engine according to (g), wherein the cam profile of the pair of swing cams is set so that the difference in amount is within a predetermined range regardless of the rotation angle of the control shaft. Valve operating device.

  According to the present invention, the lift difference between the pair of engine valves is maintained within a predetermined range regardless of any controlled lift amount of each engine valve, so that a good combustion state can be obtained.

1 is a perspective view of a main part of a valve operating apparatus for a multi-cylinder internal combustion engine provided in a first embodiment of the present invention. It is a top view which shows the principal part of the valve operating apparatus by the side bank 3 cylinder side. It is sectional drawing which shows the fall state of the rocking cam structure in a low rotation area. It is sectional drawing which shows the fall state of the rocking cam structure in a high rotation area. 1A is a view as viewed from an arrow A in FIG. 1 showing a valve closing action at the time of minimum lift control in the valve operating apparatus, and B is a view as seen from an arrow A of FIG. 1A is a view as viewed in the direction of an arrow A in FIG. 1 showing the valve closing action at the time of the maximum lift control in the valve operating apparatus, and B is a view taken in the direction of the arrow A in FIG. It is a lift characteristic view of each intake valve of each cylinder in a low rotation range and a high rotation range. It is a principal part perspective view which shows the valve operating apparatus provided to 2nd Example. It is a flowchart figure which shows the assembly | attachment procedure of each component in a present Example. It is a valve lift characteristic view of each intake valve of a low rotation range and a high rotation range based on the lift difference of each rocking cam in the 3rd example. It is a principal part side view of the valve operating apparatus which shows the cam clearance between each rocking cam and each valve lifter in 4th Example. It is principal part sectional drawing of the valve operating apparatus in 5th Example. It is a valve lift characteristic figure in a 6th example. It is a correlation diagram of the rotation angle of the control shaft and the valve lift amount in the sixth embodiment.

Explanation of symbols

2a, 2b ... Intake valve (engine valve)
3a, 3b ... Valve spring 4 ... Variable mechanism 5 ... Control mechanism 6 ... Drive mechanism 13 ... Drive shaft 15 ... Drive cam 16a / 16b ... Valve lifter 17 ... Swing cam component 18 ... Swing cam shaft 18a ... Insertion hole 19a 19b: first and second swing cams E: inner diameter of insertion hole F: outer diameter of drive shaft

Claims (4)

A drive shaft that is rotationally driven by the crankshaft of the engine and provided with a drive cam on the outer periphery;
A swing cam shaft that is pivotally supported on the outer periphery of the support shaft through an insertion hole with a predetermined clearance, and that has a pair of swing cams per cylinder on the outer periphery on both ends in the axial direction;
Two engine valves that are opened and closed by the rocking motion of the pair of rocking cams via the rocking cam shaft;
A transmission mechanism that is linked to one axial end portion of the swing cam shaft and converts the rotational motion of the drive cam into a swing motion and transmits the swing cam to the swing cam;
The rocking camshaft for each cylinder based on at least the inner diameter of the insertion hole so that the lift difference between the pair of engine valves caused by the tilting of the rocking camshaft with respect to the support shaft is equalized between the cylinders. A valve operating apparatus for a multi-cylinder internal combustion engine, characterized by being assembled selectively. A drive shaft that is rotationally driven by the crankshaft of the engine and provided with a drive cam on the outer periphery;
A swing cam shaft that is pivotally supported on the outer periphery of the support shaft through an insertion hole with a predetermined clearance, and that has a pair of swing cams per cylinder on the outer periphery on both ends in the axial direction;
Two engine valves that are opened and closed by the rocking motion of the pair of rocking cams via the rocking cam shaft;
A transmission mechanism that is linked to one axial end portion of the swing cam shaft and converts the rotational motion of the drive cam into a swing motion and transmits the swing cam to the swing cam;
A method for assembling a valve operating apparatus for a multi-cylinder internal combustion engine comprising:
Measuring the outer diameter of the support shaft and the inner diameter of the insertion hole of the swing cam shaft;
Based on the inner diameter dimension of the insertion hole measured in the measurement step so that the lift difference between the pair of engine valves accompanying the tilting of the swing cam shaft with respect to the support shaft is equalized between the cylinders. An assembly step of selectively assembling the swing cam shaft with respect to the support shaft every time;
A method of assembling a valve operating apparatus for a multi-cylinder internal combustion engine. A drive shaft that is rotationally driven by the crankshaft of the engine and provided with a drive cam on the outer periphery;
An oscillating cam shaft that is pivotally supported on the outer periphery of the support shaft through an insertion hole with a predetermined clearance, and that has two oscillating cams per cylinder on the outer periphery on both ends in the axial direction;
Two engine valves that are opened and closed by the rocking motion of the pair of rocking cams via the rocking cam shaft;
A transmission mechanism that is linked to one axial end portion of the swing cam shaft and converts the rotational motion of the drive cam into a swing motion and transmits the swing cam to the swing cam;
A method for assembling a valve operating apparatus for a multi-cylinder internal combustion engine comprising:
Measuring the outer diameter of the support shaft and the inner diameter of the insertion hole of the swing cam shaft;
Based on the inner diameter dimension of the insertion hole measured in the measurement step so that the lift difference of each engine valve caused by the tilting of the swing cam shaft relative to the support shaft is equalized between the cylinders. An assembling step of selectively assembling the different transmission mechanisms to the swing cam shaft;
A method of assembling a valve operating apparatus for a multi-cylinder internal combustion engine. In the assembly method of the valve operating apparatus of the multi-cylinder internal combustion engine according to claim 3,
After adjusting the inclination between the cylinders of the swing cam shafts in the assembling step, the lift amount of the pair of engine valves is set to one lift amount of the pair of engine valves or one of the pair of engine valves by the lift adjusting means provided in the transmission mechanism. An adjustment process for adjusting the average lift amount or lift position of the engine valve to a predetermined value;
An assembly method of a valve operating apparatus for a multi-cylinder internal combustion engine, further comprising:

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