JP2003129809A - Electromagnetic drive unit of engine valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a striking sound and generation of friction in the intermediate region of close/open stroke by suppressing a rapid action in the end region for close/open stroke of an engine valve. SOLUTION: An armature for a close/open stroke of a suction valve 23, an electromagnet for a close/open valve, a spring for a valve opening side, and a spring for a valve closing side, are provided. Inside a follower member 45 provided at an armature rod 38, a control cam 46 having a first and second follower plane 50 and 51 up and down which come in contact with a first and second follower plane 45a and 45b is provided in oscillation and universally. A return cam 47 and a sleeve 55 are integrally provided at the side of control cam 46. When an adding means 48 strikes in contact with the outer periphery face of the sleeve, a gap is formed between the adding means and the central position 54a of the cam face 54 of return cam.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic drive device which opens and closes an engine valve such as an intake valve or an exhaust valve of an internal combustion engine for an automobile mainly by electromagnetic force.

[0002]

2. Description of the Related Art As a conventional electromagnetic drive device of this type,
For example, those described in JP-A-8-21220 are known.

The outline will be described with reference to FIG. 10. An intake valve 2 slidably provided on a cylinder head 1 of an engine.
And an electromagnetic drive mechanism 3 for opening and closing the intake valve 2.

The intake valve 2 has a cap portion 2a for opening and closing the open end of the intake port 4, and a valve stem 2b integrally provided at the upper end of the cap portion 2a.

The electromagnetic drive mechanism 3 includes a cylinder head 1
A disc-shaped armature 6 is fixed to the upper end of a valve stem 2b inserted into a casing 5 fixed above, and the intake valve 2 is sucked by sucking the armature 6 in the upper and lower positions inside the casing 5. A valve closing electromagnet 7 and a valve opening electromagnet 8 that are opened and closed are arranged.

A valve opening side spring 9 for biasing the intake valve 2 in the opening direction is elastically held between the upper wall of the casing 5 and the upper surface of the armature 6, while the seat groove on the upper surface of the cylinder head 1 is held. Between the bottom surface and the bottom surface of the armature 6,
A valve-closing spring 10 that biases the intake valve 2 in the closing direction is elastically held. Further, each of the electromagnets 7 and 8 is configured to output a control current from the electronic control unit 12 to the respective coil via the amplifier 11.

The electronic control unit 12 controls the energization amount of both electromagnets 7 and 8 based on detection signals from the engine speed sensor 13 and the temperature detection sensor 14 of the valve closing electromagnet 7. In the figure, 15 is a power source.

Then, by the spring force of the two springs 9 and 10 and the attraction force of the two electromagnets 7 and 8,
The intake valves 2 are driven to open and close by accumulating the respective springs 9 and 10 as potential energy and holding them as potential energy, and alternately repeating opening and closing of electromagnetic force.

[0009]

However, in the above-mentioned conventional electromagnetic drive device, the electromagnetic attraction force of the electromagnets 7 and 8 when the intake valve 2 is opened and closed causes the springs 9 and 10 to oppose the attraction force. Therefore, when the valve is closed, the umbrella portion 2a violently collides with the valve seat 4a.
Further, when the valve is opened, the armature 6 may collide with the valve opening electromagnet 8.

That is, the principle of increasing the attractive force of the electromagnets 7 and 8 will be described with reference to FIGS. 11A and 11B.
Electromagnetic attraction force characteristics when opening and closing intake valve 2 and springs 9 and 10
The spring force characteristic of the armature 6 is first attracted upward by the attraction force of the valve closing electromagnet 7 when the valve is closed. Therefore, when the intake valve 2 slides upward, the valve closing side spring 10 is expanded, while the valve opening side spring 9 is compressed to increase the spring force, and the spring force is stored.

Next, when the valve is opened, the electromagnet 7 for closing the valve is OF
While the F signal (non-energization signal) is output, the ON signal (energization signal) is output to the valve opening electromagnet 8, and the armature 6
Is sucked downward and the intake valve 2 slides downward, the valve opening side spring 9 is extended while the valve closing side spring 1
0 is compressed, the spring force increases, and the spring force is stored.

Therefore, at the time of valve closing and valve opening, the sliding speed of the intake valve 2 is reduced by the increased spring force of the coil springs 9 and 10 on the valve opening side and valve closing side. At times, in addition to the compressed and expanded spring reaction force, the attraction force of the electromagnets 7, 8 on the attraction side suddenly increases. That is, the electromagnetic attraction force of each electromagnet 7, 8 is equal to the armature 6
And the respective fixed cores 7a and 8a of the electromagnets 7 and 8 increase in inverse proportion to the square of the distance. Therefore, the increased suction force causes the armature 6 to move abruptly upward or downward without overcoming the combined spring force on the compression and extension sides of the springs 9 and 10 and sufficiently decelerating the armature 6.

Therefore, as shown in FIG. 11A, the intake valve 2 undergoes a rapid lift-down change during maximum opening and closing, and as a result, the umbrella portion 2a collides with the valve seat 4a during closing and the armature during opening. 6 may collide with the valve-opening electromagnet 8 to generate a large hitting sound, and wear and damage of the armature 6 and the valve seat 4a may occur.

[0014]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned problems of the conventional apparatus. The invention according to claim 1 is directed to an armature associated with an engine valve and a suction of the armature. A valve-opening and valve-closing electromagnet that opens and closes the engine valve, and a valve-opening and valve-closing spring member that biases the engine valve in the closing direction and the opening direction to maintain the neutral position. And an electromagnetic drive device for an engine valve, which comprises a braking mechanism that brakes the opening / closing speed in the terminal region of the opening / closing operation of the engine valve, wherein the braking mechanism is linked to the armature,
And a follower member having a pair of follower surfaces, and a braking cam having a pair of cam surfaces for rolling the opening / closing speed in the end region of the opening / closing operation of the engine valve by rollingly contacting each of the follower surfaces as the armature moves up and down. A return cam integrally provided on a side portion of the braking cam and a cam face of the return cam are elastically contacted with each other, and when the braking cam rotates, the braking cam is substantially neutral in the rotating direction via the return cam. And a biasing means for biasing the position.

Therefore, according to the present invention, when the armature is attracted by the valve opening electromagnet when the engine is started, and the armature is lowered by the spring force of the valve opening side spring member and the follower member presses the braking cam downward, While the first ramp portion of the cam surface is rollingly contacting the first follower surface, the first lift portion of the first cam surface presses, for example, the valve stem of the intake valve to lower, that is, open the valve.

On the other hand, when the intake valve is closed, the valve-opening electromagnet is de-energized, the valve-closing electromagnet is energized, and the armature is attracted to the valve-closing electromagnet. Ascends in the valve closing direction.

When the intake valve is opened and closed,
As the follower member moves up and down, the cam surfaces of the braking cam roll on the opposing follower surfaces, and in the end region of the intake valve opening / closing operation, the contact position of one cam surface with respect to one follower surface is When the ramp portion rolls from the base portion side to the lift portion side, the contact position of the other cam surface with respect to the other follower surface is transferred from the lift portion side of the ramp portion to the base portion side. Therefore, the moment around the rotation center of the braking cam, which is generated by the spring force of the on-off valve spring member being transmitted to the braking cam via the valve stem, approaches zero. Therefore, the braking cam gradually decreases in rotation speed and stops. Along with this, the speed of the armature becomes as small as possible at its stroke end,
Similarly, the intake valve can prevent the generation of a loud collision noise at the end of its stroke.

Moreover, when the brake cam is rotated in the maximum vertical direction in the terminal region of the opening / closing operation of the intake valve, the biasing means is provided above or below the cam face of the return cam which rotates in synchronization with the brake cam. Press the side to urge the braking cam to return to the neutral position. Therefore, a strong return torque can be applied near the maximum swing position of the braking cam,
This results in a more effective braking action of the intake valve.

Further, as described above, since the urging force of the urging means is not directly applied to the braking cam but to the return cam, the shape of the cam face of the return cam is arbitrarily set. Then, on the side of the central portion, by setting the shape such that the biasing force of the biasing means is not applied greatly, except the stroke end region of the armature,
That is, a smooth opening / closing stroke is obtained without applying unnecessary braking torque in the intermediate stroke area between the opening / closing end areas of the intake valve.

According to a second aspect of the present invention, the cam face of the return cam is formed in a substantially dogleg shape.
The urging means is elastically contacted with the cam face in a direction substantially perpendicular to the axis.

The invention according to claim 3 is characterized in that a gap is formed between the cam face of the return cam and the urging means at a substantially neutral position in the rotating direction of the braking cam.

According to a fourth aspect of the present invention, a sleeve having a larger radius of curvature than the central portion of the cam face is provided so as to be rotatable relative to the return cam, and the urging means is provided on the outer peripheral surface of the cam face and the sleeve. When the biasing means elastically contacts the outer peripheral surface of the sleeve, a gap is formed between the biasing means and the central portion of the return cam.

According to a fifth aspect of the present invention, the urging means is provided in a casing accommodating the armature and the electromagnet via a bracket, and is movably provided in the cam face direction of the return cam. And a spring member for urging the plunger toward the outer side surface.

[0024]

1 shows an embodiment in which an electromagnetic drive device for an engine valve according to the present invention is applied to an intake side, and an intake valve 23 for opening and closing an opening end of an intake port 22 formed in a cylinder head 21. And an electromagnetic drive mechanism 24 for opening and closing the intake valve 23 and a braking mechanism 25 interposed between the intake valve 23 and the electromagnetic drive mechanism 24.

The intake valve 23 is provided with an umbrella portion 23a for opening and closing the opening and closing of an annular valve seat 22a attached to the opening end of the intake port 22 facing the combustion chamber, and the umbrella portion 2a.
3a, a valve stem 23b that is integrally provided at the center of the upper surface of the cylinder 3a and slides in the cylinder head 21 via a valve guide (not shown). The intake valve 23 is a spring member elastically mounted between a retainer 23c provided on the outer periphery of a cotter fixed to the stem end 23d of the valve stem 23b and a bottom surface of a holding hole 27 formed in the cylinder head 21. The spring force of the valve closing side spring 28 is urging in the closing direction.

The electromagnetic drive mechanism 24 is accommodated in a base plate 29 provided on the cylinder head 21, a cylindrical casing 34 provided on the base plate 29, and a vertically movable housing in the casing 34. A disk-shaped armature 30, an upper valve-closing electromagnet 31 and a lower valve-opening electromagnet 32 which are fixed in a vertical position with the armature 30 in a casing 34, and an intake valve through the armature 30 and the like. A valve opening side spring 33, which is a spring member that biases 23 in the opening direction, is provided.

As shown in FIG. 1, the casing 34 has a metallic cylindrical main body 34a fixed on the base plate 29 with four screws 335, and a fixed screw on one side of the upper end of the main body 34a. And a cylindrical non-magnetic material cover 34b, and a cylindrical holder (not shown) made of non-magnetic material is arranged on the inner peripheral surface of the cover 34b. Further, in this cylindrical holder, a stepped diameter non-magnetic material lid part 36 holding a valve closing electromagnet 31 is fixed to the upper end of the opening, and a bottom wall holding a valve opening electromagnet 32 to the lower end. 37 is provided.

The upper and lower surfaces of the armature 30 are arranged to face both electromagnets 31 and 32, and the upper end 38a of the armature rod 38 extending downward is fixed to the center by a nut 39, and the armature rod 38 is also provided. The follower member 4 of the braking mechanism 25, which will be described later,
5 are integrally provided. The armature rod 3
8 is slidably supported in the vertical direction via a tubular guide portion 26 that is fitted and fixed in a tubular wall provided at the center of the bottom wall 37, and its axis X is the valve stem 23 of the intake valve 23.
It is arranged coaxially with the axis Y of b, and its lower end portion 38b
The lower end edge of the abutment contacts the stem end 23d.

The on-off valve electromagnets 31 and 32 each have a fixed core formed in a substantially U-shaped cross section, and the armatures 3 are connected to each other.
Electromagnetic coils 31a and 32a are wound inside the fixed core so as to be opposed to each other with a predetermined gap S therebetween. An energization / de-energization signal from an electronic control unit 40, which will be described later, is output to the electromagnetic coils 31a and 32a, so that the armature 30 is attracted upward or downward or released.

The valve opening side spring 33 is elastically mounted between the center of the upper surface of the armature 30 and the lower surface of the lid portion 37, and when the spring force is demagnetized by the electromagnets 31 and 32, the valve closing side spring 28. The armature 30 is held in a substantially neutral position between the electromagnets 31 and 32 in balance with the spring force of the intake valve 23. In that state, the intake valve 23 is located at an intermediate position between the closed position and the maximum open position. Retained.

The electronic control unit 40 includes an engine crank angle sensor 41, an engine speed sensor 42, a temperature detection sensor 43 for detecting the temperature of the valve closing electromagnet 31, and an air flow meter 44 for detecting the engine load. Based on the detected value, energization / de-energization by the pulse signal is relatively repeatedly output to the valve closing and valve opening electromagnets 31, 32.

The rotation angle detection value from the crank angle sensor 42 is used to control the opening / closing timing of the intake valve 23 in synchronization with the rotation of the crankshaft, and the detection value from the engine speed detection sensor 43. That is, the detected value of the rotation speed of the crankshaft is used to deal with the allowable suction time of the electromagnets 31 and 32 which changes depending on the rotational speed. This is for coping with an increase in energization resistance of the electromagnetic coil 31b of the use electromagnet 31. The engine load detection value obtained by the air flow meter 44 is used together with the engine rotation speed detection value to optimally control the opening / closing timing of the intake valve 23.

The braking mechanism 25 has the structure shown in FIGS.
As shown in FIG.
b, a follower member 45 provided integrally with b, a brake cam 46 rotatably held inside the follower member 45, a return cam 47 provided integrally with the brake cam 46, and a return cam Brake cam 4 by energizing cam 47
Biasing means 4 for applying torque to return 6 to the neutral position
8 and mainly.

As shown in FIG. 2, the follower member 45 is formed in a substantially square shape on the front surface. The lower surface of the upper end wall and the flat upper surface of the lower end wall which face each other are the first follower surface 45a and the second follower surface, respectively. It is configured as 45b.

As shown in FIGS. 2 and 6, the braking cam 46 has a cam support shaft 49 fixed to the lower end of a bracket 81 fixed to a lower surface of a base plate 29 by a bolt 80 through a central hole 46a. And is rotatably supported. As shown in FIGS. 2 and 4, the braking cam 46 has a substantially fan-shaped front surface, has a substantially flat outer surface 52 on the side opposite to the main part (base circle part), and has an upper half. Is configured as an inclined first cam surface 50 on the valve opening side that is in rolling contact with the first follower surface 45a, and the entire lower surface of the lower half is in an inclined shape on the valve closing side that is in rolling contact with the second follower surface 45b. It is configured as the second cam surface 51.

Then, the first and second cam surfaces 50, 51
Are formed in the same profile as shown in FIG.
First and second base circular portions 50a and 51, which are base portions, respectively.
The first and second ramp portions 50b and 51b on the a side are formed in gentle arcuate surfaces, and the first and second lift portions 50c and 51c on the tip end side include the first and second ramp portions 50b and 51b.
b is formed in an arcuate surface having a curvature larger than that of the first and second lift portions 50c and 51c, and the third and fourth ramp portions 50d. 51d is formed. Therefore, the lift curve of the follower member 45 with respect to the rotation angle θ of the braking cam 46 is set so as to have an S-shaped curve characteristic as shown in FIG. 5, and the third and fourth ramp portions 50d. 5
Due to the presence of 1d, the sliding switching of the cam surfaces 50 and 51 can be smoothly performed when the vertical movement of the armature 30 is switched.

Further, the braking cam 46 includes the cam surfaces 50,
The base circle portions 50a and 51a of the 51 are the follower surfaces 45a and 4a.
5b between the upper and lower surfaces of the armature 30 and the upper and lower surfaces of the electromagnets 31 and 32 facing each other, respectively.
The outer diameters of the base circle portions 50a and 51a are set so as to form the minute gaps G1 and G2 as shown in FIG.

The return cam 47 is shown in FIGS.
As shown in FIG. 7, it is integrally provided on the braking cam 46 via a cylindrical connecting portion 53 that is connected to the hole edge of the central hole of the braking cam 46, and the center portion of the connecting portion 53 is continuous with the internal insertion hole. The support shaft 49 inserted into the support hole 47a is rotatably supported together with the braking cam 46. The return cam 47 is formed in a crescent shape extending in the vertical direction as a whole, and the upper and lower end portions 47b and 47c are set to be sufficiently larger than the vertical width of the braking cam 46 and the braking cam 47 is also formed. A cam face 54 is formed on the outer surface 52 side of 46. The cam face 54 is formed in a substantially V shape along the outer side surface 52, and is formed so as to be inclined downward in the vertical direction from the arc-shaped central portion 54a.

Also, the connecting portion 53 of the return cam 47.
A sleeve 55, which is rotatably supported by the support shaft 49, is disposed in contact with the side portion on the opposite side. This sleeve 5
In No. 5, the insertion hole 55a through which the support shaft 49 is inserted is formed in the center, and the outer diameter D of the outer peripheral surface 55b is set to be larger than the radius of curvature of the central portion 54a of the cam face 54. Further, a large-diameter washer 56 is provided on the side portion of the sleeve 55, and the braking cam 46, the return cam 47, the sleeve and the C-ring 57 fitted to the outer end portion of the support shaft 49 are provided by the washer 56. Inadvertent removal of 55 from the support shaft 49 is prevented.

The biasing means 48 is shown in FIG. 2, FIG. 3, and FIG.
As also shown, the bracket 83 is fixed to the lower surface of the base plate 29 by a bolt 82 and is provided at a lower end portion 83a of the bracket 83. The lower end portion 83a is bored toward the return cam 47 and the sleeve 55. Sliding hole 58,
A plunger 59 slidably provided in the sliding hole 58.
Between the pressing contact portion 60 that is integrally formed at the tip of the plunger 59 and is long in the up-down direction, the closing plate 61 that closes the opening bottom of the sliding hole 58, and the bottom surface of the inner recess of the plunger 59. Mounted on the return cam 47.
And a coil spring 62 that is a spring member that urges the support shaft 49 in the axial direction.

As shown in FIG. 2, FIG. 3 and FIG. 7, the plunger 59 is arranged so that the pressing portion 60 at the tip end thereof faces the return cam 47 and the sleeve 55 so as to face each other, and its front surface 60a. Comes into sliding contact with the rotated cam face 54 of the return cam 47 as the braking cam 46 rotates,
In the neutral position of the braking cam 46, that is, in the state where the central portion 54a of the return cam 47 faces the pressing portion 60,
The front surface 60a of the pressing portion 60 is the outer peripheral surface 55 of the sleeve 55.
A gap C having a constant width is formed between the central portion 54a region and the front surface 60a by coming into contact with b, and the central portion 54a is brought into a non-contact state.

The operation of this embodiment will be described below. First, when the engine is stopped, the energization signal is not output from the electronic control unit 40 to the electromagnetic coils 31b and 32b of the electromagnets 31 and 32, and the deenergized state is set. ing. For this reason, the armature 30, as shown in FIG.
The relative spring force of 33 holds the substantially neutral position in the gap S, and therefore the intake valve 23 is also in a neutral position slightly apart from the valve seat 22a. As shown in FIG. 1, the braking cam 46 at this point of time causes the second lift portion 51c of the second cam surface 51 to move to the follower surface 45 due to its own weight.
It is in contact with b.

When the engine is started, the electronic control unit 40
When an energization signal is output from the electromagnetic coil 32b of the valve opening electromagnet 32 to the armature 30, the armature 30 is attracted by the electromagnet 32 and is lowered by the spring force of the valve opening side spring 33. Therefore, the follower member 45 also descends via the armature rod 38, and the stem end 2 moves at the lower end 38b.
Press 3d downward. As a result, the intake valve 23
It moves downward against the spring force of the valve-closing spring 28, that is, in the direction of maximum valve opening.

On the other hand, when the intake valve 23 is closed, the energization of the valve opening electromagnet 32 is cut off, and the electromagnetic coil 31b of the valve closing electromagnet 31 is energized. The follower member 45 is raised against the spring force of the valve opening side spring 33 by the spring force of the valve side spring 28. As a result, the intake valve 23 is lifted by the spring force of the valve closing side spring 28 and is lifted.
d seats on the valve seat 22a and closes the valve.

When the intake valve 23 is opened and closed, the braking cam 46 presses the upper and lower parts of the cam face 54 of the return cam 47 against the pressing portion 60 of the plunger 59 as the follower member 45 moves up and down. While each cam surface 50, 51 is rollingly contacted with each follower surface 45a, 45b while rotating, it rotates clockwise or counterclockwise around the cam support shaft 49, so that the intake valve 23 is opened and closed as shown in FIG. 9A. In the end region (circle of broken line), effective cushioning braking action is obtained.

That is, when the intake valve 23 is closed, the urging force of the opening / closing valve side springs 33, 28 in the opening / closing direction with respect to the braking cam 46 is in the end region of the opening / closing stroke of the intake valve 23. , Respectively, close to zero.

That is, for example, when the intake valve 23 is closed, as the valve stem 23b rises due to the electromagnetic attraction force and the spring force of the valve-closing spring 28, the braking cam 4 increases.
The contact point P with the 6 is the second ramp portion 51 as shown in FIG.
It is transferred from b to the base circle portion 51a side. Therefore, the moment when the spring force of the valve-closing spring 28 is transmitted to the braking cam 46 approaches zero, so that the spring force of the valve-closing spring 28 that is transmitted from the braking cam 46 to the armature rod 38 and the armature 30 is reduced. It will approach zero. In particular, when the valve is closed, the spring reaction force of the biasing means 48 acts on the armature 30 via the return cam 47 in addition to the spring force of the valve opening side spring 33, and the resultant force increases. The intake valve 23 is effectively braked in the closing stroke end region.

The unique action also occurs when the valve is opened. Therefore, basically, the first and second brake cams 46 are
It is possible to mechanically suppress the rapid movement of the armature 30 from the ramp portions 50b and 51b to the base circle portions 50a and 51a, and as a result, the intake valve 23 opens and closes as shown in FIG. 9A (dotted line circle). A gentle operating characteristic can be obtained in the end region of the stroke. In short, the braking cam 46 swings by the attraction force of the open / close side springs 33, 28 and the electromagnets 31, 32, and the rotational moment acts to increase the braking force, and a cushioning action is obtained.

Moreover, as described above, both springs 28,
33 and the spring resultant force acting on the armature of the spring 62 of the urging means 48 have characteristics (a, b) that sharply increase from around the upper and lower limits of the armature 30, respectively, as shown on the lower side of the alternate long and short dash line in FIG. 9B. This increasing characteristic effectively acts as the braking force in the terminal region when the intake valve 23 is opened and closed.

Therefore, as shown in FIGS. 9A and 9B, the intake valve 23 can obtain a stable cushioning action during the opening / closing operation.
As a result, a violent collision between the umbrella portion 23a, the valve seat 22a, the armature 30, and the on-off valve electromagnets 32 and 33 is avoided, and the occurrence of tapping noise, wear, or damage is prevented.

Further, in this embodiment, the armature 3 is used.
At the maximum ascent and descent of 0, since a positive minute gap is formed between the upper and lower surfaces of the armature 30 and the facing surfaces of the electromagnets 31, 32 by the braking cam 46, the armature 30 and the electromagnets 31, 32 are It is possible to more reliably avoid the collision.

As described above, the intake valve 23
For example, when the braking cam 46 tries to swing up and down to the maximum in the end region of the closing operation, the plunger 59 uses the spring force of the coil spring 62 to generate the cam face 54 of the return cam 47 as shown in FIG. The lower side is pressed to urge the braking cam 46 to return to the neutral position. Therefore, a strong return torque is applied to the braking cam 46 in the direction of the neutral position in the vicinity of the maximum upward rotation position. This provides a more effective braking action on the armature 30.

On the other hand, even in the end region when the intake valve 23 is opened, the plunger 59 pushes the upper side of the cam face 54 of the return cam 47 and urges the braking cam 46 to return to the neutral position. Therefore, a strong return torque is applied to the braking cam 46 in the direction of the neutral position in the vicinity of the maximum upward rotation position. This provides a more effective braking action on the armature 30.

Further, in this embodiment, as described above, when the intake valve 23 is slightly opened and the braking cam 46 is in the substantially neutral position, as shown in FIG. The front surface 60a is the outer peripheral surface 55 of the sleeve 55.
Since a gap C is formed between the front surface 60a and the outer peripheral surface 54a of the central portion 54 of the return cam 47 by elastically contacting a, the areas C (FIG. 9B) are not in contact with each other.
The friction between the return cam 47 (braking cam 46) in the area c below the alternate long and short dash line) does not occur, and only a small amount occurs between the return cam 47 and the sleeve 55 side. Can be significantly reduced. Therefore, the armature 30 and the intake valve 23 in this intermediate region are prevented from lowering the operating speed during the opening / closing stroke, and a smooth operation is obtained.

Further, since the braking cam 46 is supported by both the cam support shaft 49 and the return cam 47 on both sides of the plunger 59, the supporting rigidity of the braking cam 46 becomes high and its swinging motion. It is stable and reliable. As a result, the upper and lower surfaces of the armature 30 and the electromagnets 31, 3 are
The fluctuation of the minute gap formed between the two opposing surfaces is suppressed, and the collision between the respective members as described above can be reliably avoided.

Further, the biasing means 48 in this embodiment
Is not provided directly on the braking cam 46 but is provided on the casing main body 34a, so that an increase in inertial force of the armature 30 can be suppressed and durability can be improved.

The present invention can be applied not only to the intake valve side but also to the exhaust valve side. When it is applied to the exhaust valve side, the rapid movement of the exhaust valve at the time of opening can be regulated so that combustion can be performed. Rapid discharge of gas is suppressed, and as a result, exhaust noise can be reduced. In addition, the braking mechanism 25
The return cam 47 can have the shape of its cam face 54 arbitrarily set so as to promote the reduction of the braking force and the braking torque at the intermediate position, and the biasing means 4
The spring force of the coil spring 62 of No. 8 can also be freely set in consideration of the braking force and the like.

Further, at the neutral position in the rotating direction of the braking cam 46, the cam face 5 of the return cam 47 is provided.
When a gap is formed between the plunger 4 and the plunger pressing portion 60, the maximum advance position of the plunger 59 can be restricted by a predetermined stopper or the like to avoid contact with the cam face 54. become.

[0059]

As is apparent from the above description, claim 1
According to the invention described in (1), since the sudden opening / closing operation in the opening / closing end region of the engine valve can be sufficiently braked by the braking cam, a violent collision between the umbrella portion and the valve seat or between the armature and the opening / closing valve electromagnet is mitigated. . As a result, it is possible to prevent the occurrence of a violent impact hammering sound and the occurrence of wear or damage.

Moreover, when the braking cam swings to the maximum in the vertical direction in the end region of the opening / closing operation of the engine valve, the biasing means presses the upper side or the lower side of the cam face of the return cam to neutralize the braking cam. To urge it back into position,
A strong return torque can be applied near the maximum swing of the braking cam. This provides a more effective braking action.

Further, when the braking cam is in the substantially neutral position as described above, the biasing means greatly reduces the friction between the return cam and the central portion of the cam face due to the cam face shape of the return cam. be able to. Therefore, the armature and the engine valve in this intermediate region are prevented from lowering the operating speed during the opening / closing stroke, and a smooth operation is obtained.

According to the second aspect of the invention, since the cam face of the return cam has a substantially V-shaped smooth shape, the action of the braking cam in the terminal region of the opening / closing operation of the engine valve is as described above. In addition to this, it is possible to further enhance the braking effect, and it is possible to effectively suppress the occurrence of friction by the biasing means in the region of the neutral position of the braking cam.

According to the third and fourth aspects of the invention, the gap can more effectively prevent the friction between the braking cam and the urging means from occurring therebetween. Therefore, it is possible to further prevent a decrease in the operating speed of the armature or the engine valve.

According to the fifth aspect of the present invention, since the biasing means is provided separately from the movable member such as the braking cam, an increase in the inertial mass of the armature is suppressed, and the actuation response of the armature is suppressed. It can prevent the deterioration.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the present embodiment.

FIG. 3 is a plan view of a main part of this embodiment.

FIG. 4 is a front view showing a braking cam used in the present embodiment.

FIG. 5 is a characteristic diagram showing the rotation angle of the braking cam with respect to the vertical stroke of the armature.

FIG. 6 is an exploded perspective view showing some components of the braking mechanism used in the present embodiment.

7 is a cross-sectional view taken along the line AA of FIG.

FIG. 8 is an operation explanatory view of the present embodiment.

9A is a buffer characteristic diagram when the intake valve is opened and closed, and B is a characteristic diagram of attraction force of each electromagnet and spring force of each spring.

FIG. 10 is a vertical sectional view showing a conventional device.

FIG. 11A is a characteristic diagram of opening / closing timing of an intake valve, and B is a characteristic diagram of attraction force of each electromagnet and spring force of each spring.

[Explanation of symbols]

21 ... Cylinder head 23 ... Intake valve 25 ... Braking mechanism 28 ... Valve closing spring 30 ... Armature 31 ... Electromagnet for valve closing 32 ... Electromagnet for opening valve 33 ... Valve opening side spring 38 ... Armature rod 45 ... Follower member 46 ... Braking cam 47 ... Return cam 48 ... Biasing means 49 ... Support shaft 50 ... 1st cam surface 51 ... Second cam surface 54 ... Cam face

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akira Onuki             1370 Onna, Atsugi, Kanagawa             Nissia Jex (72) Inventor Shingo Yoshizawa             1370 Onna, Atsugi, Kanagawa             Nissia Jex F term (reference) 3G016 AA02 AA05 BA34 BA35 BA36                       BA37 BA44 CA08 CA09 CA10                       CA25 CA45 CA46 DA01 DA23                       GA04                 3G018 AB08 AB09 AB16 BA02 BA38                       CA11 CA12 DA34 DA36 DA43                       DA70 DA83 DA85 FA01 FA06                       FA07 GA02 GA23 GA27

Claims (5)

[Claims] 1. An armature linked to an engine valve, valve-opening and valve-closing electromagnets for sucking the armature to open and close the engine valve, and closing and opening the engine valve. In an electromagnetic drive device for an engine valve, which is provided with a spring member for opening and closing the valve member that is biased and held in a neutral position, and a braking mechanism that brakes the opening / closing speed in the terminal region of the opening / closing operation of the engine valve, The braking mechanism is a follower member that is linked to the armature and has a pair of follower surfaces, and rolls on each follower surface as the armature moves up and down to brake the opening / closing speed in the terminal region of the opening / closing operation of the engine valve. Braking cam having a pair of cam surfaces, a return cam integrally provided on a side portion of the braking cam, and a cam face of the return cam elastically contacting the retarding cam when the braking cam rotates. Electromagnetic drive device of the engine valve, characterized in that a biasing means for biasing the brake cam via a cam substantially neutral position in the rotational direction. 2. The cam face of the return cam is formed in a substantially dogleg shape, and the biasing means is elastically contacted with the cam face in a direction substantially perpendicular to the axis. An electromagnetic drive device for an engine valve according to. 3. A gap is formed between the cam face of the return cam and the urging means at a substantially neutral position in the turning direction of the braking cam.
Alternatively, the electromagnetic drive device of the engine valve according to the item 2. 4. A sleeve having a larger radius of curvature than the central portion of the cam face is provided so as to be rotatable relative to the return cam, and the biasing means is elastically contacted over the cam face and the outer peripheral surface of the sleeve. The gap is formed between the biasing means and the central portion of the return cam when the biasing means elastically contacts the outer peripheral surface of the sleeve. Electromagnetic drive for engine valves. 5. The plunger is provided in a casing accommodating the armature and an electromagnet via a bracket, and the biasing means is provided so as to be movable back and forth in the cam face direction of the return cam, and the plunger is provided on the outer surface. An electromagnetic drive device for an engine valve according to any one of claims 1 to 4, wherein the electromagnetic drive device comprises a spring member that biases in a direction.