JP7028010B2 - Internal combustion engine valve train - Google Patents

Description

The present disclosure relates to a valve train of an internal combustion engine, and more particularly to a valve train for opening and closing an intake valve or an exhaust valve (collectively referred to as an engine valve) of an internal combustion engine.

In such a valve operating device, the camshaft is rotationally driven by the crankshaft, and the cam provided on the camshaft opens the engine valve against the urging force of the valve spring.

When opening and closing the engine valve, the camshaft has a valve opening torque (this is called positive torque) that tries to push the camshaft back in the opposite direction of rotation, that is, in the reverse direction, by the urging force of the valve spring, and the camshaft. Is alternately generated with a valve closing torque (this is referred to as a negative torque) that tries to push forward in the rotation direction, that is, in the forward rotation direction. Due to this torque fluctuation, the rotation fluctuation of the camshaft occurs, and due to this rotation fluctuation, for example, a gear provided on the camshaft and a gear meshed with the gear to transmit the rotational driving force from the crankshaft. There is a problem that a rattle sound (striking sound) is generated between the and.

Therefore, conventionally, the camshaft is provided with a cancel cam for generating a cancel torque having an opposite phase so as to cancel the fluctuation torque (see, for example, Patent Documents 1-3).

Japanese Unexamined Patent Publication No. 2010-84526 Japanese Unexamined Patent Publication No. 7-332026 Japanese Unexamined Patent Publication No. 6-42314

However, if a variable mechanism that makes the valve timing of the engine valve variable is provided, the phase of the fluctuating torque generated on the camshaft changes, so the torque canceling effect is not always satisfactory when the phase of the cancel cam is constant. I can't get it.

Therefore, the present disclosure was devised in view of the above circumstances, and the purpose of the present disclosure is to obtain a sufficient torque canceling effect even when a variable mechanism for changing the valve timing of the engine valve is provided. Is to provide.

According to one aspect of the present disclosure.
A camshaft that is rotationally driven by the crankshaft of an internal combustion engine and has a cam that opens the engine valve against the urging force of the valve spring.
A first variable mechanism configured to make the valve timing of the engine valve variable with respect to the crank phase,
A cancel cam provided on the camshaft and generating a cancel torque on the camshaft that cancels the fluctuation torque generated on the camshaft by opening and closing the engine valve.
A second variable mechanism configured to make the phase of the cancel cam variable with respect to the crank phase,
A valve train for an internal combustion engine is provided.

Preferably, a plurality of the cancel cams are provided.

Preferably, the camshaft comprises an outer camshaft and an inner camshaft that is rotatably and coaxially inserted into the outer camshaft.
The cam is fixed to one of the outer camshaft and the inner camshaft, and the cancel cam is fixed to the other.
The second variable mechanism includes the outer camshaft and the inner camshaft.

Preferably, the first variable mechanism includes a plurality of the cams having different profiles and a switchable rocker arm that selectively connects a part of the plurality of the cams to the engine valve.

Preferably, the valve operating device is configured to control the first variable mechanism and the second variable mechanism, and a control unit that changes the phase of the cancel cam in response to a change in valve timing of the engine valve. Further prepare.

According to the present disclosure, a sufficient torque canceling effect can be obtained even when a variable mechanism for making the valve timing of the engine valve variable is provided.

It is a schematic vertical sectional view of a valve train. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. It is a schematic plan view of a valve train. It is a valve lift diagram which shows the state of the change of the valve timing. It is a figure which shows the profile of the cancellation cam. It is a cam lift diagram of a cancel cam. It is a graph which shows the fluctuation torque and the total torque for each cylinder. It is a graph which shows the cancel torque and the total cancel torque for each cancel cam. It is a graph which shows the total torque when there is no cancel cam, and the total torque when there is a cancel cam. It is a graph which shows the cam lift amount of each cylinder, and the total torque at the time of the 1st variable mechanism in the 1st state. It is a graph which shows the cam lift amount of each cylinder, and the total torque in the 2nd state of the 1st variable mechanism. It is a graph comparing the total torque when the first variable mechanism is in the first state and the second state. It is a graph which shows the total torque when the 1st variable mechanism is in the 1st state, the total cancel torque of the phase position which is most suitable for canceling this, and the total torque which added these. It is a graph which shows the total torque when the optimum total cancel torque is given in the 2nd state in the 1st state. It is a graph which shows the total torque in the 2nd state, the optimum total cancel torque generated by this embodiment in the 2nd state, and the total torque which added these.

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

1 to 3 show the valve operating device of this embodiment. FIG. 1 is a schematic vertical sectional view of the valve operating device, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 is a schematic plan view of the valve operating device.

The internal combustion engine (engine) of the present embodiment is a multi-cylinder diesel engine mounted on a large vehicle such as a truck or a bus, and specifically, an in-line 6-cylinder diesel engine. However, the uses and types of vehicles and engines are not limited and are arbitrary.

The rotational driving force from the crankshaft (not shown) is transmitted to the camshaft 1 through a power transmission mechanism (not shown) including a gear mechanism. The engine of the present embodiment is a DOHC (Double OverHead Camshaft) engine, and the camshaft 1 is an intake camshaft for opening and closing an intake valve. However, additionally or alternatively, the present disclosure may be applied to an exhaust camshaft for driving an exhaust valve (not shown). Intake valves and exhaust valves are collectively called engine valves.

For convenience, one end side (left side in FIG. 1) in the direction (axial direction) of the central axis C1 of the camshaft 1 is referred to as front, and the other end side (right side in FIG. 1) is referred to as rear. These front-rear directions coincide with the front-rear directions of the engine and the vehicle (the engine is placed vertically). However, they do not necessarily have to match.

The valve operating device is such that the camshaft 1 having cams 4A, 4B, 4C that opens the intake valve 3 against the urging force of the valve spring 2 and the valve timing of the intake valve 3 with respect to the crank phase are variable. The configured first variable mechanism 5 and the cancel cams 6A and 6B provided on the camshaft 1 and generating a cancel torque on the camshaft 1 that cancels the fluctuation torque generated on the camshaft 1 by opening and closing the intake valve 3. A second variable mechanism 7 configured to make the phases of the cancel cams 6A and 6B variable with respect to the crank phase is provided.

Two intake valves 3 are provided for each cylinder, and these two intake valves 3 are opened and closed at the same time by the valve bridge 8. When the intake valve 3 is opened, a part of the three cams 4A, 4B, 4C and the rocker arm 9 causes the valve bridge 8 to move downward against the urging force of the valve spring 2 (the back side in the paper thickness direction in FIG. 3). It is pushed down in the direction toward). On the other hand, when the intake valve 3 is closed, on the contrary, the valve bridge 8 is pushed upward (in the direction toward the front side in the paper thickness direction in FIG. 3) by the urging force of the valve spring 2.

The camshaft 1 has a hollow tubular outer camshaft 10 and an inner camshaft 11 that is rotatably and coaxially inserted into the outer camshaft 10. The inner camshaft 11 is solid, but may be hollow. The camshaft 1 is sandwiched between the lower cam carrier 12 and the upper cylinder head 13 and is rotatably supported in the radial direction. The outer camshaft 10 is provided with flanges 14 and 15 that sandwich the cam carrier 12 and the cylinder head 13 in the axial direction and position the camshaft 1 in the thrust direction.

At the rear end of the camshaft 1 located behind the cam carrier 12 and the cylinder head 13, the outer camshaft 10 is provided with an input gear 17 to which the final gear 16 of the power transmission mechanism described above is engaged. The outer camshaft 10 receives a rotational driving force from the crankshaft through the input gear 16.

In the present embodiment, the cam that opens the intake valve 3 includes three cams per cylinder, that is, the first cam 4A, the second cam 4B, and the third cam 4C. These three cams 4A, 4B, and 4C form a first variable mechanism 5, and both the valve timing and the working angle of the intake valve 3 are switched in three stages. The cams 4A, 4B, 4C are fixed to the outer camshaft 10.

Further, the first variable mechanism 5 includes a rocker arm 9, and the rocker arm 9 has three rocker arms per cylinder corresponding to the three cams 4A, 4B, and 4C, that is, the first rocker arm 9A and the second rocker arm. Includes 9B and 3rd rocker arm 9C. These rocker arms 9A, 9B, and 9C are adjacent to each other in the front-rear direction and are rotatably supported by a common rocker shaft 18. C2 indicates the central axis of the rocker shaft 18. The arrangement order of these cams and rocker arms in the axial direction is arbitrary, but in the present embodiment, the second, first, and third are in order from the rear.

A rocker roller 19 is rotatably provided on the rocker arms 9A, 9B, 9C, and the rocker roller 19 is constantly in contact with the cams 4A, 4B, 4C. Further, only the first rocker arm 9A is provided with an extending portion 20 that is engaged with the upper surface portion of the valve bridge 8. By switching the connection state of the second and third rocker arms 9B and 9C with respect to the first rocker arm 9A, the valve timing and the like can be switched in three stages.

Inside the rocker arms 9A, 9B, 9C, four pins 21Aa, 21Ab, 21B, 21C for switching these connected states are provided so as to be movable in the axial direction. Further, inside the second rocker arm 9B, a spring 22 that can collectively urge the four pins 21Aa, 21Ab, 21B, and 21C to the front is provided. The positions of the pins 21Aa, 21Ab, 21B, 21C are controlled by supplying and discharging hydraulic pressure to the first and third hydraulic passages 23A, 23C provided inside the first and third rocker arms 9A, 9C, respectively. Will be done.

The first variable mechanism 5 sets both the valve timing and the working angle of the intake valve 3 to one of three states as shown in FIG. 4, that is, the first state S1, the second state S2, and the third state S3. It is configured to switch to the target. Here, the valve timing includes both the opening timing at which the engine valve starts valve opening and the closing timing at which the engine valve ends the valve closing. The working angle means a crank phase period or a cam phase period in which the engine valve is open (that is, the valve lift amount VL is larger than zero).

In the present embodiment, the maximum valve lift period (the period in which the valve lift amount VL is the maximum valve lift amount VLmax) is gradually extended to the retard side from the first state S1 to the third state S3. , The first to third states S1 to S2 are set. The valve lift curve from the open timing α1 to the maximum valve lift amount start timing α2 is the same in all states. After the maximum valve lift amount start timing α2, the valve closing is started immediately in the first state S1, and the valve closing is started after the maximum valve lift amount VLmax is maintained for the second predetermined period Δα2 in the second state S2. In the three state S3, the valve closing is started after the maximum valve lift amount VLmax is maintained for a longer third predetermined period Δα3. The closing timing of the first state S1 is set to α3, the closing timing of the second state S2 is set to the later α4, and the closing timing of the third state S3 is set to the later α5. The working angle of the first state S1 is a period from α1 to α3, the working angle of the second state S2 is a longer period of α1 to α4, and the working angle of the third state S3 is a longer period of α1 to α5. .. Therefore, in the present embodiment, the opening timing is fixed, while the closing timing and the working angle are changed in three stages.

The outer shapes of the first to third rocker arms 9A, 9B, and 9C are the same. On the other hand, the cam profiles of the first to third cams 4A, 4B, and 4C are set to different cam profiles corresponding to the first to third states S1, S2, and S3, respectively.

When the intake valve 2 is driven in the first state S1, hydraulic pressure is supplied to the first hydraulic pressure passage 23A, and hydraulic pressure is discharged from the third hydraulic pressure passage 23C. Then, the pins 21Aa and 21Ab are moved in the front-rear direction so as to be separated from each other, the pin 21B is pressed backward against the urging force of the spring 22, and the pin 21C is pressed forward. Then, the rear end surface of the pin 21Aa and the front end surface of the pin 21Ab are arranged flush with the rear end surface and the front end surface of the first rocker arm 9A, and the front end surface of the pin 21B faces the front end surface of the second rocker arm 9B. Arranged in one, the rear end surface of the pin 21C is arranged flush with the rear end surface of the third rocker arm 9C. As a result, the first rocker arm 9A is not connected to the second rocker arm 9B and the third rocker arm 9C, and only the operation of the first cam 4A is transmitted to the intake valve 2 through the first rocker arm 9A. Then, the other second and third rocker arms 9B and 9C simply follow the movements of the second and third cams 4B and 4C and perform a missed motion (lost motion).

Next, when the intake valve 2 is driven in the second state S2, hydraulic pressure is discharged from the first hydraulic passage 23A and the third hydraulic passage 23C. Then, the pin 21B is pushed forward by the spring 22 and inserted into the first rocker arm 9A, and the second rocker arm 9B is connected to the first rocker arm 9A (state in FIG. 3). On the other hand, the remaining pins 21Aa, 21Ab, 21C are pushed forward by the pins 21B, and the pins 21Ab and the pins 21C are positioned at the same positions as in the first state S1. As a result, the first rocker arm 9A and the third rocker arm 9C are in a non-connected state. Therefore, the intake valve 2 is substantially opened and closed by the second cam 4B via the integrated first and second rocker arms 9A and 9B.

Next, when the intake valve 2 is driven in the third state S3, hydraulic pressure is supplied to the third hydraulic pressure passage 23C, and the hydraulic pressure is discharged from the first hydraulic pressure passage 23A. Then, the pin 21C is pushed backward by hydraulic pressure and inserted into the first rocker arm 9A, and the third rocker arm 9C is connected to the first rocker arm 9A. On the other hand, the remaining pins 21Aa, 21Ab, 21B are pushed backward by the pins 21C against the urging force of the spring 22, and the pins 21Aa and the pins 21B are positioned at the same positions as in the first state S1. As a result, the first rocker arm 9A and the second rocker arm 9B are in a non-connected state. Therefore, the intake valve 2 is substantially opened and closed by the third cam 4C via the integrated first and third rocker arms 9A and 9C.

In the present embodiment, a plurality of cancel cams are provided, specifically, two cancel cams, that is, a first cancel cam 6A on the rear side and a second cancel cam 6B on the front side are provided. The first and second cancel cams 6A and 6B are fitted to the outer peripheral portion of the outer camshaft 10 so as to be relatively rotatable, and are fixed to the inner camshaft 11 by a press-fit pin 24. The penetrating portion of the press-fit pin 24 on the outer camshaft 10 is an elongated hole extending in the circumferential direction.

Similar to the cams 4A, 4B and 4C, these cancel cams 6A and 6B also have rocker arms 25A and 25B and valve bridges 26A and 26B for canceling when the camshaft 1 (specifically, the inner camshaft 11) rotates. By pushing down the springs 27A and 27B via the camshaft 1, a cancel torque is generated with respect to the camshaft 1. The torque canceling mechanism is configured in substantially the same manner as the above-mentioned intake valve drive mechanism, and the only difference is that there is no intake valve 2. Therefore, the torque canceling mechanism can be manufactured at low cost by diverting the parts of the intake valve drive mechanism.

The canceling first and second rocker arms 25A and 25B are configured in the same manner as the first rocker arm 9A described above, have a rocker roller 19 and an extending portion 20, and are rotatably supported by a common rocker shaft 18. Will be done. These rocker arms 25A and 25B are not connected to each other and operate individually. Two cancellation first and second springs 27A and 27B are provided for each of the cancellation cams 6A and 6B, respectively. These springs 27A and 27B are sandwiched and installed between the canceling first and second valve bridges 26A and 26B and the upper surface portion of the cam carrier 12. The outer dimensions of the springs 27A and 27B are substantially the same as the outer dimensions of the valve spring 2, and the valve bridges 26A and 26B are the same as the valve bridge 8 described above. Therefore, it is possible to reduce costs by standardizing parts. When the cancel cams 6A and 6B compress the springs 27A and 27B and are pushed back by the springs 27A and 27B, a positive torque is applied to the camshaft 1, and the cancel cams 6A and 6B extend the springs 27A and 27B to extend the springs 27A and 27B. A negative torque is applied to the camshaft 1 when it is pushed forward by 27B.

In the case of this embodiment, # 1 cylinders to # 6 cylinders are arranged in order from the front, and the camshaft 1 corresponds to the opening and closing of the intake valve 2 of each cylinder per one engine cycle (= 720 ° crank phase). Six times (= N times, N is the number of cylinders) periodic fluctuation torque is generated. Since it is sufficient to generate the anti-phase cancel torque that cancels this fluctuation torque six times, in principle, one cancel cam having six (N) cam lob portions may be provided on the camshaft 1.

However, in this case, since it is necessary to process as many as 6 cam lob portions on the entire circumference of the short cancel cam, there is a problem that the processing of the cam lob portions is difficult or practically impossible. Therefore, in the present embodiment, a plurality of cancel cams, specifically two (n = 2), are provided for one camshaft 1, and cancellation torque is generated three times (= N / n times) for each cancel cam. I am trying to make it. As a result, the number of cam lob portions to be processed into one cancel cam can be reduced to half (3 = N / n), and the processing of the cam lob portions can be facilitated.

FIG. 5 shows the cam profile of the first cancel cam 6A. Further, FIG. 6 shows a cam lift diagram of the first cancel cam 6A. The first cancel cam 6A has three cam lob portions 29 having the same shape at equal intervals in the circumferential direction (120 ° = 360 / (N / 2) ° cam phase interval) protruding outward in the radial direction from the base circle 28. Have. The first cancel cam 6A generates a positive cancel torque each time the spring 27A is pushed down by these cam lob portions 29. The second cancel cam 6B also has the same cam profile as the first cancel cam 6A. The first cancel cam 6A and the second cancel cam 6B are fixed to the inner camshaft 11 in a state where they are 60 ° (= 360 / (N / 2) / 2 °) out of phase with each other by 60 ° (= 360 / (N / 2) / 2 °). It produces a cancellation torque of 60 ° cam phase spacing, i.e. 120 ° crank phase spacing.

By the way, in the present embodiment, the second variable mechanism 7 for making the phases of the cancel cams 6A and 6B variable with respect to the crank phase is provided. Hereinafter, the configuration of the second variable mechanism 7 will be described.

As shown in FIGS. 1 and 2, the second variable mechanism 7 is formed at the rear end of the outer camshaft 10 and the rear end of the inner camshaft 11 and rotates relative to each other in the housing 30. It has a rotor 31 that can be accommodated.

As shown in FIG. 2, a plurality of (four) housing vanes 32 protruding inward in the radial direction are formed in the housing 30 at equal intervals in the circumferential direction, and a hydraulic chamber 33 is formed between the housing vanes 32. On the other hand, a plurality (four) rotor vanes 34 protruding outward in the radial direction are formed in the rotor 31 at equal intervals in the circumferential direction, and these rotor vanes 34 partition each hydraulic chamber 33 in front of and behind the camshaft rotation direction R. Of the partitioned hydraulic chambers 33, the advance angle chamber 35 is located rearward in the rotation direction, and the retard angle chamber 36 is located forward in the rotation direction.

When the hydraulic pressure of the advance chamber 35 becomes higher than the hydraulic pressure of the retard chamber 36, the rotor 31 is advanced with respect to the housing 30, and the phases of the cancel cams 6A and 6B with respect to the crank phase are advanced. On the other hand, when the hydraulic pressure of the retard chamber 36 becomes higher than the hydraulic pressure of the advance chamber 35, the rotor 31 is retarded with respect to the housing 30, and the phases of the cancel cams 6A and 6B with respect to the crank phase are retarded.

When the hydraulic pressure of the advance chamber 35 and the hydraulic pressure of the retard chamber 36 are held equally, the rotor 31 is held in a fixed position without rotating relative to the housing 30. Therefore, the phases of the cancel cams 6A and 6B with respect to the crank phase are also kept constant.

Inside the inner camshaft 11, an advance angle oil passage 37 communicated with the advance angle chamber 35 and a retard angle oil passage 38 communicated with the retard angle chamber 36 are formed. Inside the cylinder head 13, an advance angle oil supply hole 39 for communicating the advance angle oil passage 37 with the oil gallery 41 is formed. Inside the cam carrier 12, a retarding oil supply hole 40 for communicating the retarding oil passage 38 with the oil gallery 41 is formed. The oil gallery 41 is a space formed inside the cylinder block to store high-pressure oil.

The high-pressure oil in the oil gallery 41 is selectively supplied to the advance angle oil supply hole 39 and the retard angle oil supply hole 40 via an oil control valve (OCV) 42. The OCV 42 is controlled by a control unit, a circuit element (circuitry), or an electronic control unit (referred to as an ECU) 100 as a controller. The ECU 100 controls the engine and includes a CPU, ROM, RAM, an input / output port, a storage device, and the like.

At the time of phase advance of the cancel cams 6A and 6B, the ECU 100 controls the OCV 42 so as to supply hydraulic pressure to the advance angle oil supply hole 39 and discharge the hydraulic pressure from the retard angle oil supply hole 40. On the other hand, when the cancel cams 6A and 6B are in phase retard, the ECU 100 controls the OCV 42 so as to supply hydraulic pressure to the retard oil supply hole 40 and discharge the hydraulic pressure from the advance oil supply hole 39.

When the phases of the cancel cams 6A and 6B are kept constant, the ECU 100 controls the OCV 42 to supply hydraulic pressure to both the advance angle oil supply hole 39 and the retard angle oil supply hole 40.

When switching between the first to third states S1, S2, and S3 described above, the hydraulic pressure supply / discharge to the first hydraulic passage 23A and the third hydraulic passage 23C can also be switched by controlling the switching valve (not shown) by the ECU 100. conduct.

Next, the operation of this embodiment will be described.

The variable torque generated in the camshaft 1 (outer camshaft 10) for each opening and closing of the intake valve of each cylinder from the # 1 cylinder to the # 6 cylinder is as shown by the line a in FIG. For each variable torque, when the cam 4A pushes down the intake valve 3 against the urging force of the valve spring 2 when the intake valve 3 is opened, it will be pushed back to the camshaft 1 (outer camshaft 10). A positive torque is generated in the direction opposite to the rotation direction R. Further, when the intake valve 3 is closed, the valve spring 2 conversely tries to push the cam 4A and the camshaft 1 (outer camshaft 10) in the rotation direction R, so that the camshaft 1 is in the same direction as the rotation direction R. Negative torque is generated.

When the variable torques for each cylinder are added together, the total torque as shown by line b in FIG. 7 is obtained. Here, as a premise, it is assumed that the first variable mechanism 5 is set to the first state S1.

On the other hand, the variable torque, that is, the cancel torque generated on the camshaft 1 (inner camshaft 11) by the first and second cancel cams 6A and 6B, respectively, is as shown by lines c and d in FIG. The positive and negative of the cancel torque are as described above. Further, when these cancel torques c and d are added together, a total cancel torque as shown by line e in FIG. 8 is obtained.

As can be seen by comparing FIGS. 7 and 8, the total cancel torque e has a crank phase shifted by 60 ° from the total torque b and is in the opposite phase. Therefore, the total torque b can be canceled by the total cancel torque e, and the torque fluctuation of the camshaft 1 due to the opening and closing of the intake valve 3 can be suppressed.

FIG. 9 shows the total torque b when the cancel cams 6A and 6B are not present. Further, FIG. 9 shows the total torque when the cancel cams 6A and 6B are present, that is, the total torque f as a result of adding the total torque b and the total cancel torque e. As can be seen from this figure, the torque fluctuation of the camshaft 1 can be significantly suppressed.

By suppressing the torque fluctuation of the camshaft 1 in this way, the rotational fluctuation of the camshaft 1 can be suppressed. Then, it is possible to reduce the rattle sound (teeth tapping sound) generated between the input gear 17 provided on the camshaft 1 and the final gear 16 meshed with the input gear 17. Generally, a scissors gear may be provided to reduce the rattle noise, but in the present embodiment, the scissors gear can also be omitted, so that the manufacturing cost can be reduced.

By the way, when the state of the first variable mechanism 5 changes, the valve timing and the working angle change, and the phase position of the fluctuating torque changes. Therefore, when the phase positions of the cancel cams 6A and 6B are fixed at a fixed position, a satisfactory torque canceling effect cannot always be obtained in all the states of the first variable mechanism 5.

Therefore, in the present embodiment, the second variable mechanism 7 is provided so that the phase positions of the cancel cams 6A and 6B can be changed. As a result, the phase positions of the cancel cams 6A and 6B can be changed according to the state change of the first variable mechanism 5, and a sufficient torque canceling effect can be obtained.

This point will be described in detail below. FIG. 10 shows the camlift amount g of each cylinder (# 1 to # 6 cylinders) when the first variable mechanism 5 is in the first state S1, and the total torque h of the camshaft 1 caused only by opening and closing the intake valve. .. Here, the total torque h does not include the cancel torque.

Similarly, FIG. 11 shows the camlift amount i of each cylinder (# 1 to # 6 cylinders) when the first variable mechanism 5 is in the second state S2, and the total torque j of the camshaft 1 caused only by opening and closing the intake valve. Is shown.

The former total torque h and the latter total torque j can be summarized in FIG. 12 as shown in FIG. From the figure, it can be seen that the total torque j in the second state S2 is slightly shifted to the advance angle side from the total torque h in the first state S1.

FIG. 13 shows the total torque h in the first state S1 shown in FIG. 10, the total cancel torque k at the optimum phase position for canceling the total torque h, and the total torque l obtained by adding these. As can be seen, the total torque h changes to the total torque l, and the torque fluctuation is greatly suppressed. In this case, the second variable mechanism 7 is controlled by the ECU 100 so that the total cancel torque k at the phase position as shown in the figure can be obtained.

However, if the optimum total cancel torque k for the first state S1 is given in the second state S2, the torque fluctuation may worsen as shown in FIG. FIG. 14 shows the total cancel torque k, the total torque j in the second state S2 shown in FIG. 11, and the total torque m obtained by adding these. As can be seen, the total torque j changes to the total torque m, and it can be seen that the torque fluctuation is significantly increased.

Therefore, in the present embodiment, the second variable mechanism 7 is controlled by the ECU 100 so that the optimum total cancel torque is generated in the second state S2.

FIG. 15 shows the total torque j in the second state S2, the total cancel torque n generated by the present embodiment in the second state S2, and the total torque o obtained by adding these. As can be seen, the total cancel torque n having the opposite phase shifted by 60 ° from the total torque j is generated. Then, the total torque j changes to the total torque o, and the torque fluctuation is greatly suppressed. In this case, the second variable mechanism 7 is controlled by the ECU 100 so that the total cancel torque n at the phase position as shown in the figure can be obtained.

As described above, according to the present embodiment, a sufficient torque canceling effect can be obtained even when the first variable mechanism 5 for making the valve timing of the intake valve 3 variable is provided.

Although only the cases of the first state S1 and the second state S2 have been described here, the same applies to the case of the third state S3.

By the way, when a torque fluctuation based on the opening and closing of the intake valve occurs in the camshaft 1 (outer camshaft 10), the hydraulic pressure of the advance chamber 35 fluctuates due to this, and the hydraulic pulsation in the same phase as the torque fluctuation becomes an oil gallery. It occurs in the passage on the OCV42 side from 41. Then, this hydraulic pulsation is transmitted to another oil supply unit 43 (see FIG. 1) connected to the oil gallery 41 via the oil gallery 41, and may affect the oil supply unit 43.

However, according to the present embodiment, since the torque fluctuation due to the opening and closing of the intake valve can be suppressed in any state of the first variable mechanism 5, such hydraulic pulsation is suppressed and the influence on another oil supply unit 43 is reduced. It is possible to do.

As can be understood from the above description, the second variable mechanism 7 includes an outer camshaft 10 and an inner camshaft 11. The first variable mechanism 5 selectively connects a plurality of cams 4A, 4B, 4C fixed to the outer camshaft 10 and different profiles, and a part of the plurality of cams 4A, 4B, 4C to the intake valve 3. Includes a switchable rocker arm 9. The ECU 100 is configured to control the first variable mechanism 5 and the second variable mechanism 7, and changes the phases of the cancel cams 6A and 6B in response to a change in the valve timing of the intake valve 3.

Although the embodiments of the present disclosure have been described in detail above, the present disclosure can also be implemented by other embodiments and modifications.

(1) In the above embodiment, the first variable mechanism 5 is switchable in three stages, but it may be switchable in two stages, four stages or more, or steplessly. Further, the configuration of the first variable mechanism 5 can be arbitrarily changed, and may be an electromagnetically driven type or a pneumatic type.

(2) In the above embodiment, there are two cancel cams 6A immediately before the rearmost cams 4A, 4B, 4C of the # 6 cylinder, or between the cams 4A, 4B, 4C of the # 5 cylinder and the # 6 cylinder. , 6B were provided. However, the number of cancel cams is arbitrary, and if there are no restrictions such as that the cam lob can be processed without any problem, one cancel cam may be used. Conversely, the number of cancel cams may be three or more. Further, the cancel cam should have a total number of camlobs equal to the number of cylinders of the camshaft provided with the cancel cam. For example, in the case of a V-type DOHC 6-cylinder engine, 3 (= N / 2) camlobs per camshaft. It is better to have. The installation position of the cancel cam is also arbitrary.

(3) In the above embodiment, a torque canceling mechanism including a rocker arm 25A, 25B, a valve bridge 26A, 26B, and a spring 27A, 27B is used in order to generate a cancel torque by the cancel cams 6A, 6B. However, the mechanism can be changed as appropriate.

(4) In the above embodiment, the second variable mechanism 7 that can be switched steplessly independently of the switching of the first variable mechanism 5 is provided. However, the second variable mechanism may be switchable in conjunction with the switching of the first variable mechanism, or may be shared with the first variable mechanism. Further, the second variable mechanism may be switchable in stages.

(5) In the above embodiment, the closing timing of the engine valve (intake valve 3) is variable, but it is possible to make the opening timing variable or both the opening timing and the closing timing variable. At this time, the working angle may be variable or constant.

(6) The relationship between the outer and inner camshafts 10 and 11 and the cams 4A, 4B, 4C and the cancel cams 6A, 6B may be reversed. That is, the cams 4A, 4B, 4C may be fixed to the inner camshaft 11, and the cancel cams 6A, 6B may be fixed to the outer camshaft 10. In this case, the input gear 16 may be provided on the inner camshaft 11.

The embodiments of the present disclosure are not limited to the above-described embodiments, and all modifications, applications, and equivalents included in the ideas of the present disclosure defined by the scope of claims are included in the present disclosure. Therefore, this disclosure should not be construed in a limited way and may be applied to any other technique that falls within the scope of the ideas of this disclosure.

1 Camshaft 2 Valve spring 3 Intake valve 4A, 4B, 4C Cam 5 1st variable mechanism 6A, 6B Cancel cam 7 2nd variable mechanism 9 Rocker arm 10 Outer camshaft 11 Inner camshaft 100 Electronic control unit

Claims (5)

A camshaft that is rotationally driven by the crankshaft of an internal combustion engine and has a cam that opens the engine valve against the urging force of the valve spring.
A first variable mechanism configured to make the valve timing of the engine valve variable with respect to the crank phase,
A cancel cam provided on the camshaft and generating a cancel torque on the camshaft that cancels the fluctuation torque generated on the camshaft by opening and closing the engine valve.
A second variable mechanism configured to make the phase of the cancel cam variable with respect to the crank phase,
A valve train for an internal combustion engine, characterized by being equipped with. The valve operating device for an internal combustion engine according to claim 1, wherein a plurality of cancellation cams are provided. The camshaft comprises an outer camshaft and an inner camshaft that is rotatably and coaxially inserted into the outer camshaft.
The cam is fixed to one of the outer camshaft and the inner camshaft, and the cancel cam is fixed to the other.
The valve operating device for an internal combustion engine according to claim 1 or 2, wherein the second variable mechanism includes the outer camshaft and the inner camshaft. The first variable mechanism includes a plurality of the cams having different profiles and a switchable rocker arm in which a part of the plurality of cams is selectively connected to the engine valve. The valve operating device for an internal combustion engine according to any one of the following items. Any of claims 1 to 4, further comprising a control unit configured to control the first variable mechanism and the second variable mechanism and changing the phase of the cancel cam in response to a change in valve timing of the engine valve. The valve engine of the internal combustion engine according to item 1.

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