JPH0610634A - Intake and exhaust valve driving controller of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent crash noise, wear or the like from occuring in respective parts by a change in the rotational torque of a cam shaft, and driving load from being increased by shutting off the transmission of the change in the rotational torque onto a driving mechanism. CONSTITUTION:Between the flange part of a sleeve and the flange part of a cam shaft 22 connected to a driving shaft 21, a circular disc housing 34 is mounted so that it may oscillate smoothly. The center Y of a circular disc 29 and the center X of the driving shaft 21 are made eccentric to each other with the oscillation of a disc housing 34. The disc housing 34 is constituted so that its one end may be oscillatingly-supported to a supporting shaft 39 and the other end may be oscillated by screwing the male-threaded part 50 of a rotating member 42 in the female-threaded part 46 of a movable member 41.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake / exhaust valve drive control device for variably controlling the opening / closing timing of intake / exhaust valves according to the operating state of an internal combustion engine.

[0002]

2. Description of the Related Art Various conventional devices of this type have been provided, and one of them is, for example, Shoukai 57-198.
Those described in Japanese Patent No. 306, etc. are known.

The outline will be described with reference to FIGS. 10 and 11. Reference numeral 2 in the drawing is rotatably provided on the outer periphery of the camshaft 1 to open the intake valve 16 against the spring force of the valve spring 17. The cam 2 is a cam that is axially positioned by a cam bearing bracket 3 and a flange portion 5 fixed to the cam shaft 1 via a key 4. A flange portion 7 having a U-shaped groove 6 is formed on one side of the cam 2, and a U-shaped groove 8 is also formed on the flange portion 5 so as to form an annular shape between the flange portions 5 and 7. Disk 9 is inserted. This disc 9
Are provided with pins 10 and 11 that engage with the U-shaped grooves 6 and 8 at opposite positions on both sides, and the outer circumference is a control ring 1.
It is rotatably supported by 2. The control ring 12 has a support hole 13 on the cylinder head side through a protrusion 12a on the outer circumference.
The rocker arm 15 has an arcuate gear portion 12b which is swingably supported by the rocker arm 15 and is provided on the opposite side of the projection 12a.
Is meshed with a spur toothed gear ring 14a formed on the outer periphery of the rocker shaft 14 that axially supports.

The control ring 12 is oscillated in one direction or the other direction according to the engine operating state by a drive mechanism (not shown) via a gear ring 14a meshed with the gear portion 12b. That is, when the center P of the disc 9 is at the position shown in FIG. While rotating in synchronization with
The cam 2 rotates synchronously with the cam shaft 1 via the pin 10 and the U-shaped groove 6.

When the rocker shaft 14 is rotated by the hydraulic actuator of the drive mechanism as the engine operating condition changes, the control ring 12 swings around the projection 12a as a fulcrum via the gear ring 14a and the gear portion 12b. As a result, the center P of the disc 9 is eccentric with respect to the center of the camshaft 1 in the rotation direction. Therefore, the pins 10 and 11 move along the U-shaped grooves 6 and 8, respectively, and rotate the flange portions 5 and 7 in the eccentric direction about the cam shaft 1. Therefore, the rotational phase of the disk 9 changes with respect to the camshaft 1 and the rotational phase of the cam 2 also changes with respect to the disk 9 for each rotation of the camshaft 1. Therefore, the cam 2 rotates with respect to the camshaft 1 with a phase difference that is twice the phase difference of the disc 9 with respect to the camshaft 1. As a result, the valve timing can be changed according to the phase difference of the cam 2.

[0006]

However, in the above-mentioned conventional apparatus, the control ring 12 is swung by the meshing rotation of the arcuate gear portion 12b and the spur gear gear ring 14a. A comparison formed between the gear portion 12b and the gear ring 14a by the alternating load acting on the control ring 12 due to the positive and negative rotational torque fluctuations generated in the camshaft 1, that is, the repeated load in the forward and reverse rotation directions. A striking sound is generated between the two 12b and 14a due to the relatively large backlash clearance, and abrasion is generated between the both 12b and 14a over time, and the swinging action of the control ring 12 becomes unstable. . As a result, the variable control accuracy of the valve timing is reduced.

Moreover, since the gear portion 12b and the gear ring 14a serve as spur gears and simply transmit the rotary motion as they are, the camshaft 1
The rotational fluctuation torque generated in the gear part 12b and the gear ring 1
It is directly transmitted from the rocker shaft 14 to the hydraulic actuator via 4a. For this reason, the drive load of the hydraulic actuator becomes large, so that the drive capacity of the hydraulic actuator and the like must be increased, which inevitably leads to an increase in the size of the entire apparatus and a cost increase.

[0008]

The present invention has been devised in view of the above-mentioned problems of the prior art, and includes a camshaft having a cam for driving an intake / exhaust valve by a rotational force transmitted from an engine, An annular disc housing provided so as to be swingable in a substantially radial direction with respect to the axis of the cam shaft, and rotatably held on the inner peripheral surface of the disc housing while being linked to the cam shaft, An intake / exhaust system including a disc whose center is eccentric with the shaft center of the camshaft in accordance with the swing, and which obtains a change in the angular velocity of the camshaft with the eccentricity of the disc to variably control the operating angle of the intake / exhaust valve. In the valve drive control device, a movable member having a female screw hole formed along the tangential direction of the disc housing is provided on one end side of the disc housing, and the female member is provided on the outer periphery. Flip is characterized in that a forward and reverse rotation being controlled rotary member by the male screw portion screwed into hole is formed and a drive mechanism.

[0009]

When the center of the disk is aligned with the axial center of the camshaft, the angular velocity of the camshaft does not change and synchronizes with the engine.

On the other hand, when the rotating member is rotated in one direction by the drive mechanism as the operating condition of the engine changes, the movable member on the female screw portion linearly slides as the male screw portion rotates. In other words, the rotary motion is converted into a linear motion to swing the disc housing in one direction. Therefore, the disc is also swung so that the center of the disc is decentered from the axial center of the camshaft by a predetermined amount. Therefore, the angular velocity of the camshaft changes, and the rotational speed of the camshaft is partially increased or decreased, whereby the operating angles of the intake and exhaust valves are variably controlled.

Further, the disk housing is not a gear, but is oscillated by screwing movement of the female screw portion of the movable member with respect to the male screw portion of the rotating member, and there is almost no backlash gap between the female and male screw portions. Since it is not formed, even if an alternating load is generated on the disk housing due to fluctuations in the rotational torque of the camshaft, it is possible to prevent hammering noise between the female and male threaded parts and the occurrence of wear over time.

Moreover, since the fluctuation of the rotational torque transmitted to the disk housing is absorbed by the conversion of the movement between the female and male screw portions, the transmission of the fluctuation torque to the drive mechanism is interrupted and the increase of the driving load is prevented. it can.

[0013]

1 to 6 show a first embodiment of an intake / exhaust valve drive control device according to the present invention, in which reference numeral 21 denotes a rotational force transmitted from a crankshaft of an engine (not shown) via a sprocket. The drive shaft 22 is a hollow cam shaft which is arranged on the outer periphery of the drive shaft 21 with a constant gap and is coaxial with the center X of the drive shaft 21.
Is extended in the front-rear direction of the engine and is formed in an inner hollow shape in order to reduce the weight.

The cam shaft 22 is rotatably supported by a cam bearing (not shown) provided on the upper end of the cylinder head 20, and an intake valve 23 is provided at a predetermined position on the outer circumference as shown in FIGS. A plurality of cams 26 ... Which are opened against the spring force of the spring 24 via the valve lifter 25 are integrally provided. Also, the camshaft 2
2 is divided and formed from a direction perpendicular to the axis at a predetermined position in the longitudinal direction, and a flange portion 27 is provided on one divided end portion. In addition, the sleeve 2 is provided between the divided ends.
8 and an annular disc 29 are arranged. As shown in FIG. 4, the flange portion 27 is provided with an elongated rectangular engaging groove 30 extending from the hollow portion in the radial direction, and one side surface of the annular disc 29 in the circumferential direction of the outer peripheral surface thereof. The protrusion surface 27a that is slidably contacted with is integrally provided.

The sleeve 28 has a small diameter one end portion 28b.
Is rotatably inserted into the other end of the camshaft 22 on the other side, and is fixedly connected to the drive shaft 21 via a connecting shaft 31 penetrating diametrically at a substantially central position. Further, as shown in FIG. 5, the flange portion 32 provided at the other end of the sleeve 28 is provided with an elongated rectangular engaging groove 33 along the radial direction on the side opposite to the engaging groove 30. At the same time, the outer peripheral surface is integrally provided with a protruding surface 28a that is in sliding contact with the other side surface of the annular disk 29.

The annular disc 29 has a substantially toroidal plate shape, an inner diameter of which is substantially the same as the inner diameter of the cam shaft 22, and an annular gap S is formed between the annular disc 29 and the outer peripheral surface of the drive shaft 21. In addition, the outer peripheral portion 29a is rotatably supported by the inner peripheral surface 34a of the annular disc housing 34 via a metallic annular bearing 35. In addition, pin holes 29b and 29c formed at the opposite positions on the diameter line.
Has a pair of pins 36, which engage with the respective engagement grooves 30, 33.
37 is provided. The pins 36 and 37 project in opposite directions to each other in the axial direction of the cam shaft, the bases are rotatably supported in the pin holes 29b and 29c, and the pins 36 and 37 are provided on both side edges of the tip end in FIGS. As shown in FIG. 3, the facing inner surfaces 30a, 30b, 33a of the engaging grooves 30, 33,
33b, flat portions 36a, 36b, 3 having a width across flats,
7a and 37b are formed.

As shown in FIGS. 1 and 3, the disc housing 34 has a substantially annular shape, and a support hole 38 is formed through the boss member 34b at one end of the outer periphery in the axial direction of the camshaft 22. While it is swingably provided up and down in the figure with a support shaft 39 inserted into the support hole 38 as a fulcrum, a lever portion 40 is provided on the outer peripheral surface opposite to the boss portion 34b in the radial direction. It is projected integrally.
Then, at the substantially spherical tip portion 40a of the lever portion 40,
A movable member 41 that slides up and down is connected via a rotating member 42. A base portion of the support shaft 39 is press-fitted and fixed in a fixing hole 60a of a bracket 60 fixed to the upper surface of the cylinder head 20.

The movable member 41 has a substantially rectangular shape, and its length L in the vertical direction is set to be sufficiently long. Also,
The tip portion 40a of the lever portion 40 is slidably held in a substantially U-shaped holding groove 43 formed in one side portion, and the holding groove 43 is provided in a bolt hole 41a provided at the upper portion of the one side portion.
An adjustment bolt 44 for adjusting the clearance between the inner surface of the lever and the outer surface of the lever end 40a is screwed and fixed via a nut 45. Further, in the other side portion of the movable member 41, a female screw hole 47 having a spiral female screw portion 46 formed on the inner circumference is vertically formed so as to penetrate therethrough. Both sides of the movable member 41 are vertically slid and guided by the guide members 48 on the cylinder head 20.

The rotating member 42 has a bolt shape, a lower end 42a thereof is axially supported in a support groove 20a on the upper surface of the cylinder head 20, and an upper end 42b thereof is a bearing of a bracket 49 fixed to the cylinder head 20. The whole is rotatably supported in the hole 49a via a flange 42c. Further, a spiral male screw portion 50 that is screwed into the female screw portion 46 is formed on the entire outer peripheral surface from the flange portion 42c to the lower end portion 42a. In addition, the rotating member 42 has a driving mechanism 5 that is linked to the upper end portion 42b.
The forward and reverse rotation control is performed by 1.

As shown in FIGS. 1 and 2, the drive mechanism 51 includes a pair of bevel gears 52, 53 provided on the upper end portion 42b of the rotating member 42 and meshed with each other, and a bevel gear 53 having one end on one side. A control shaft 54 connected to the control shaft 54 and a rotary stepping motor 55 connected to the other end of the control shaft 54. The other side bevel gear 52
Is fixed to the upper end portion 42b of the rotating member 42. Further, the stepping motor 55 is configured to drive forward and reverse rotation based on a pulse control signal output from the control unit 56. The control unit 56 has a microcomputer incorporated therein for a crank angle sensor and an air flow. A current engine operating state is detected based on information signals from various sensors such as a meter and an engine cooling water temperature sensor, and a pulse signal is output.

The operation of this embodiment will be described below.
First, when the engine speed is low and the load is low, the control unit 5
When a predetermined pulse control signal is output from 6 and the stepping motor 55 rotates in one direction, both bevel gears 52 and 53 rotate while meshing via the control shaft 54. Therefore, the rotary member 42 to which the rotational force is transmitted rotates in one direction via the support groove 20a and the bearing hole 49a. That is, when the male screw portion 50 rotates, the movable member 41 moves downward by a predetermined length f via the female screw portion 46 as shown in FIG.
Only move linearly. Therefore, the disc housing 34 swings downward around the support shaft 39 via the lever portion 40, and the center Y of the annular disc 29 is set to the drive shaft 2.
1 (camshaft 22) is eccentrically moved from the center X by an amount of ε. Therefore, the engagement groove 33 and the pin 37 on the sleeve 28 side, and the engagement groove 30 and the pin 36 on the camshaft 21 side.
The sliding positions of and move with each rotation of the drive shaft 21, and the angular velocity of the annular disk 29 changes, resulting in unequal angular velocity rotation.

That is, when the sliding position of the locking groove 30 and the pin 36 approaches the center X of the drive shaft 21, the sliding position of the locking groove 33 and the pin 37 is separated from the center X. In this case, the annular disc 29 has a large angular velocity with respect to the drive shaft 21, and the angular velocity of the camshaft 22 also becomes large with respect to the annular disc 29. Therefore, the camshaft 22 is partially doubled in speed with respect to the drive shaft 21.

On the other hand, when the engine shifts to the high speed and high load region, the control unit 56 outputs a pulse control signal in the opposite direction to the above, the stepping motor 55 rotates in the reverse direction, and the control shaft 54, the bevel gear 52, The rotating member 42 also reversely rotates via 53. Therefore, the movable member 41
Is linearly slid upward by the screwing action of the male and female screw portions 46 and 50 and returns to the original position shown in FIG. Therefore, the disc housing 34 also swings to the original position, and the center Y of the annular disc 29 coincides with the center X of the drive shaft 21 (see FIG. 1). Therefore, in this case, a rotational phase does not occur between the annular disc 29 and the drive shaft 21, and the center of the camshaft 22 and the center Y of the annular disc 29 are also aligned, so that the space between the two 22 and 29 is the same. No rotational phase difference occurs. Therefore, as the drive shaft 21 rotates, the connecting shaft 3
1, the sleeve 28 rotates synchronously, and the cam shaft 22 also rotates synchronously via the engagement groove 33 on the sleeve side and the pin 37, the annular disc 29, the pin 36, and the engagement groove 30 on the cam shaft 22 side.

As a result, the rotational phase difference between the camshaft 22 and the cam 26 and the drive shaft 21 changes as shown in FIG. 7A based on the changes in the respective angular velocities, and the valve timing changes as shown in FIG. The valve lift changes according to the phase difference of the cam shaft 22 with the valve lift kept constant.

That is, when the angular velocity of the camshaft 22 is relatively high, the rotational phase with respect to the drive shaft 21 advances until both the speeds 21 and 22 become constant, and eventually when the angular velocity of the camshaft 22 relatively decreases. Phase is both 2
Delay until 1 and 22 become constant speed. Then, as shown in FIG. 7A, the same phase point (point P) exists in the middle of the maximum and minimum points of the rotational phase difference, and the change in the rotational phase shown by the broken line in FIG. The valve opening timing of 23 is delayed, the valve closing timing after point P is advanced, and the valve operating angle is reduced as shown by the broken line in FIG. 7B. Therefore, as described above, in the engine low speed and low load region, the valve timing of the intake valve 23 becomes smaller as shown by the broken line in FIG. 7B, the opening timing is slightly delayed, and the closing timing is advanced. As a result, the valve overlap of the intake and exhaust valves is reduced, the residual gas in the combustion chamber is reduced, and stable combustion improves fuel efficiency. Further, the early closing timing improves the intake charging efficiency and can increase the low speed torque.

On the other hand, in the high speed and high load region, the operating angle becomes large as shown by the solid line in FIG. 7B, and the closing timing becomes late as the operating timing becomes early, so that the intake charging efficiency utilizing the intake inertial force is improved. However, high output can be achieved. In the high speed and high load range, the movable member 41 is further moved upward to move the disk housing 34 and the annular disk 2 shown in FIG.
If 9 is further swung upward, the operating angle of the intake valve 23 becomes even larger as shown by the alternate long and short dash line in FIG. 7B, and it is possible to promote higher output.

As described above, in this embodiment, the valve timing can be variably controlled with high accuracy according to the change in engine operation, and the disk housing 34 can be moved by the movable member 41 without using gears as in the conventional case. The male and female screw portions 46 and 50 of the rotating member 42 and the rotating member 42 are used for swinging, and there is almost no backlash gap formed between the thread and the screw groove of the female and male screw portions 46 and 50. Even if an alternating load is generated in the disc housing 34 due to fluctuations in the rotational torque of the camshaft 22, the female and male threaded portions 46, 50
It is possible to prevent the tapping sound and the occurrence of wear over time.
In particular, since the length L of the movable member 41 in the vertical direction, that is, the length of the female screw hole 47 is set to be sufficiently long, the screw groove of the female screw portion 46 and the screw thread of the male screw portion 50 are different due to an error in the screw pitch or the like. The gap is further reduced, and the generation of tapping noise is effectively prevented.

Moreover, the alternating load transmitted from the disk housing 34 to the movable member 41 via the lever portion 40 is absorbed when the linear movement is converted into the rotational movement between the female and male screw portions 46 and 50. . Therefore, the transmission of the alternating load to the stepping motor 55 is reliably cut off, and an increase in the rotational driving load is prevented.

Further, the stepping motor 55 having a high control accuracy is rotationally driven and the male and female screw portions 46 and 50 having a small pitch are used.
Since the disc housing 34 is swung by utilizing the deceleration action of, the eccentric movement of the annular disc 29 with respect to the drive shaft 21 can be finely controlled. As a result, the valve timing control accuracy is improved.

Further, as described above, since both edges of the pins 36, 37 are formed on the flat portions 36a, 36b, 37a, 37b, the facing inner surfaces 30a of the locking grooves 30, 33,
It comes into contact with 30b, 33a and 33b in a surface contact state. Therefore, the flat surface portion 36 during rotation transmission from the drive shaft 21 to the camshaft 22 and in the eccentric state of the annular disk 29.
a, 36b, 37a, 37b and facing inner surfaces 30a, 30
When sliding with b, 33a and 33b, a concentrated load between them is prevented from being generated, and the surface pressure is reduced. As a result, the locking groove 3
0, 33 and the pins 36, 37 are prevented from being worn over time, and the tapping noise between the flange portions 27, 32 and the pins 36, 37 due to the fluctuation of the rotational torque of the camshaft 22 and the valve are prevented. It is possible to prevent a decrease in control accuracy due to a timing shift.

Further, since the pins 36 and 37 are rotatably supported by the pin holes 29b and 29c of the annular disc 29, the pins 3 and 37 can be rotated even when the annular disc 29 swings.
6 and 37 are rotated appropriately so that the flat portions 36a, 36b and 37
a, 37b and inner facing surfaces 30a, 30 of the locking grooves 30, 33
b, 33a and 33b are always in surface contact with each other. Therefore, the occurrence of wear between the both 30, 36, 33, 37 is more reliably prevented.

8 to 9 show a second embodiment of the present invention,
Instead of swingably supporting the disc housing 34 by a support shaft, the movable member 41 is integrally provided directly at the other end of the disc housing 34, and the movable member 41 linearly moves the disc housing 34 in the vertical direction. It was made to rock.

Therefore, according to this embodiment, the disk housing 34 moves up and down in parallel with the rotary member 42 via the movable member 41 as the rotary member 42 rotates forward and backward.
For this reason, it is possible to swing the disk housing 34 more than the amount of vertical movement of the movable member 41 in the first embodiment. That is, in the case of the first embodiment, since it is the fulcrum swing, in order to obtain the predetermined amount of eccentricity ε of the disk housing 34, the movable member 41 requires a movement amount f of more than that, but in the present embodiment In the example, the disk housing 34 moves in parallel (moves).
The movement amount e of 1 and the movement amount e of the disc housing 34 are the same. As a result, the moving amount of the movable member 41 can be reduced, and therefore the responsiveness of the operation angle conversion of the intake valve 23 is improved by shortening the moving time.

Further, in this way, the disc housing 34
Since the amount of movement of the intake valve 23 is the same as the amount of movement of the movable member 41, the swing amount of the disk housing 34 can be increased conversely. Therefore, the change range of the operating angle of the intake valve 23 should be increased. You can

In addition, in this embodiment, a support shaft and the like are not required, so that not only the number of parts and the cost can be reduced, but also the movable member 41 with respect to the drive shaft 21 is integrated by integrating the disc housing 34 and the movable member 41. Female screw hole 47
The positioning and so-called centering work of the disc housing 34 and the disc housing 34 become extremely easy.

It is also possible to use a DC motor, a hydraulic motor or the like other than the stepping motor 55 of the drive mechanism 51.

[0037]

As is apparent from the above description, according to the present invention, the eccentric swing of the disk housing with respect to the camshaft is not performed by a gear or the like as in the conventional case, but the back of the movable member and the rotating member is moved. Since it is performed by the screwing movement of the male and female screw parts with a small lash gap, the occurrence of hammering noise and wear due to the fluctuation of the rotational torque of the camshaft is prevented.

Moreover, since the alternating load of the disk housing due to the fluctuation of the rotating torque is effectively absorbed between the male and female screw portions, the transmission of the alternating load to the drive mechanism is interrupted and the increase of the driving load is prevented. As a result, the drive mechanism can be downsized, and the degree of freedom in layout is improved.

[Brief description of drawings]

FIG. 1 is a sectional view taken along line AA of FIG. 2 showing an embodiment of the present invention.

FIG. 2 is a plan view showing a main part of this embodiment.

3 is a sectional view taken along line BB of FIG.

FIG. 4 is a sectional view taken along the line CC of FIG.

5 is a cross-sectional view taken along line DD of FIG.

FIG. 6 is a sectional view taken along the line AA of FIG. 3 showing the operation of the present embodiment.

FIG. 7 is a characteristic diagram of a valve timing and a rotational phase difference between a drive shaft and a cam shaft according to the present embodiment.

FIG. 8 is a sectional view of a main part showing a second embodiment of the present invention.

FIG. 9 is a cross-sectional view of the main parts showing the operation of this embodiment.

FIG. 10 is a sectional view of a conventional intake / exhaust valve drive control device.

11 is a sectional view taken along line FF of FIG.

[Explanation of reference numerals] 21 ... Drive shaft 22 ... Cam shaft 23 ... Intake valve 29 ... Annular disc 34 ... Disc housing 34a ... Inner peripheral surface 41 ... Movable member 42 ... Rotating member 46 ... Female screw part 47 ... Female screw hole 50 ... Male screw Part 51 ... Drive mechanism

Claims (1)

[Claims] 1. A cam shaft having a cam for driving an intake / exhaust valve by a rotational force transmitted from an engine, and an annular disc provided so as to be swingable substantially in a radial direction with respect to the axis of the cam shaft. The disc includes a housing and a disc that is rotatably held on the inner peripheral surface of the disc housing while being linked to the camshaft, and the center of which is eccentric with the axial center of the camshaft as the disc housing swings. In an intake / exhaust valve drive control device that variably controls the operating angle of the intake / exhaust valve by obtaining a change in the angular velocity of the camshaft with eccentric movement, at one end side of the disc housing,
A movable member having a female screw hole formed along the tangential direction of the disc housing is provided inside, and a male screw portion that is screwed into the female screw hole is formed on the outer periphery, and a rotating member that is controlled to rotate forward and backward by a drive mechanism is provided. An intake / exhaust valve drive control device for an internal combustion engine, which is provided.