JP2000314305A - Solenoid driven valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solenoid driven valve preventing a valve opening action of a valve element due to rebound of an amature during a valve closing drive, and preventing decrease of a valve closing force applied on the valve element. SOLUTION: In this solenoid driven valve, a shock absorbing mechanism 66 is provided between an armature shaft 36 and a valve shaft 26. The shock absorbing mechanism 66 comprises a shock absorbing spring 68 and a preset housing 70. The preset housing 70 restricts the length of the shock absorbing spring 68 contained inside in the axial direction to be a length L1 shorter than a natural length L0. A clearance C1 is formed between an outer edge part 78 of the bottom end of the armature shaft 36 and a top end of the shock absorbing spring 68, when a valve element 24 is fully closed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetically driven valve, and more particularly to an electromagnetically driven valve provided with an elastic body between a valve body and an armature shaft for preventing the valve body from rebounding during a valve closing operation.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Unexamined Patent Application Publication No.
As disclosed in No. 35, an electromagnetically driven valve is known.
The conventional electromagnetically driven valve includes a valve body functioning as an intake valve or an exhaust valve of the internal combustion engine, an armature shaft disposed coaxially with the valve body, and an armature fixed to the armature shaft. . The valve body and the armature shaft are provided apart from each other in the axial direction, and an elastic body made of a coil spring is interposed at the separated portion.

[0003] An upper coil and an upper core are disposed above the armature. A lower coil and a lower core are provided below the armature. Each of the upper coil and the lower coil generates an electromagnetic force for attracting the armature when an exciting current is supplied. According to the above-described conventional electromagnetically driven valve, by supplying an exciting current to the upper coil, the armature can be attracted to the upper coil and the valve body can be displaced in the valve closing direction. In this case, the valve body is fully closed by the armature abutting on the upper core. Further, by supplying an exciting current to the lower coil, the armature can be attracted to the lower coil to displace the valve body in the valve opening direction. In this case, when the armature contacts the lower core, the valve body is fully opened. Therefore, by supplying the exciting current to the upper coil and the lower coil at an appropriate timing, the exhaust valve or the intake valve can be repeatedly opened and closed between the fully open state and the fully closed state.

[0004] The armature that is attracted by the upper coil and is displaced upward may rebound when it comes into contact with the lower surface of the upper core. On the other hand, in the above conventional example, the rebound of the armature is buffered by the coil spring provided between the valve body and the armature shaft. Therefore, according to the above-described conventional electromagnetically driven valve, unnecessary valve opening operation of the valve element due to the rebound of the armature at the time of valve closing drive is prevented.

[0005]

In the above-described conventional electromagnetically driven valve, the coil spring provided between the armature shaft and the valve shaft has a natural function when the valve body is fully closed with the valve seated on the valve seat. It is kept slightly compressed than its length. As a result, the urging force of the coil spring is transmitted to the valve body as a force in the valve opening direction, so that the force for holding the valve body at the fully closed position (hereinafter, referred to as valve closing force) decreases. It becomes difficult to maintain the valve body in the fully closed state. In the above-mentioned conventional electromagnetically driven valve, in order to more reliably prevent the valve opening operation of the valve body due to the recoil of the armature at the time of valve closing drive, the larger the coil spring having a larger spring constant is applied, the larger the urging force is. Since it is provided in the direction, it becomes difficult to maintain the valve body in the fully closed state. If the valve body cannot be completely closed, a so-called gas blow-through phenomenon in which combustion gas unnecessarily blows from the combustion chamber to the exhaust port or the intake port occurs, and the combustion efficiency of the internal combustion engine decreases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and prevents a valve opening operation of a valve body due to a rebound of an armature at the time of valve closing drive, and also prevents a reduction in valve closing force on the valve body. It is an object of the present invention to provide an electromagnetically driven valve that can perform the operation.

[0007]

The above object is achieved by the present invention.
As described in the above, an armature driven by the cooperation of the electromagnetic force of the electromagnetic coil and the urging force of the urging member, an armature shaft extending in the axial direction of the armature, and coaxially spaced from the armature shaft And a resilient member interposed between the valve body and the armature shaft, wherein the armature is provided when the valve body is fully closed. This is achieved by an electromagnetically driven valve having regulating means for regulating the axial length of the elastic body to a predetermined length shorter than the natural length so that a predetermined clearance is formed between the shaft and the elastic body. You.

In such an electromagnetically driven valve, the elastic body prevents the valve body from opening due to the rebound of the armature during the valve closing drive. Further, when the valve body is closed, the length of the elastic body is regulated to a predetermined length shorter than the natural length by the regulating means, and a predetermined clearance is formed between the armature shaft and the elastic body. No urging force is applied to the valve body in the valve opening direction. Thus, according to the present invention,
It is possible to prevent the armature from bouncing off during the valve closing drive and to prevent a decrease in the force for maintaining the valve body in the fully closed position.

[0009]

FIG. 1 is an overall configuration diagram of an electromagnetically driven valve 10 according to one embodiment of the present invention. Electromagnetic drive valve 10
Constitutes an exhaust valve of the internal combustion engine 12. As shown in FIG. 1, the internal combustion engine 12 includes a lower head 14 and an upper head 16 fixed to an upper portion of the lower head 14. An exhaust port 18 is formed in the lower head 14. Further, a combustion chamber 20 is provided below the lower head 14.
Are formed. A valve seat 22 is formed at an open end of the exhaust port 18 on the combustion chamber 20 side.

The electromagnetically driven valve 10 has a valve element 24. The valve element 24 shuts off between the exhaust port 18 and the combustion chamber 20 by sitting on the valve seat 22, and conducts between the exhaust port 18 and the combustion chamber 20 by separating from the valve seat 22. The valve body 24 has a valve shaft 26. The valve shaft 26 is slidably held in the axial direction by a valve guide 28 fixed inside the lower head 14 of the internal combustion engine 12. A lower retainer 30 is fixed to an upper portion of the valve shaft 26. Lower head 1
Inside 4, the cylindrical portion 32 is formed around the valve shaft 26. A lower spring 34 is provided between the lower surface of the lower retainer 30 and the lower surface of the cylindrical portion 32. The lower spring 34 is connected to the valve body 2 via the lower retainer 30.
4 is urged upward in FIG.

The electromagnetically driven valve 10 includes an armature shaft 3
6 is provided. The armature shaft 36 is
It is arranged coaxially with and spaced apart upward. The armature shaft 36 is a rod-shaped member made of a non-magnetic material. An upper retainer 38 is fixed to an upper end of the armature shaft 36. The lower end of the upper spring 40 is in contact with the upper part of the upper retainer 38. The upper end of the upper spring 40 is in contact with the adjustment bolt 42. The upper spring 40 urges the armature shaft 36 via the retainer 38 downward in FIG.

A disk-shaped armature 44 is joined to the outer periphery of the armature shaft 36. Armature 44
Is a member made of a soft magnetic material. A cylindrical portion 46 is formed around the armature shaft 36 in the upper head 16. In the cylindrical portion 46, an upper coil 48 and an upper core 50 are disposed above the armature 44. Further, a lower coil 52 and a lower core 54 are disposed below the armature 44 in the cylindrical portion 46. The upper coil 4
8 and the energization of the lower coil 52 are controlled by an electronic control unit (hereinafter referred to as an ECU) 56.

The upper core 50 and the lower core 54 are
Both are members made of a magnetic material. Upper core 5
The lower core 54 and the lower core 54 have through holes 58 and 60, respectively, which penetrate the center. An upper bearing 62 is provided at an upper end of the through hole 58 provided in the upper core 50. Further, a lower bearing 64 is provided at a lower end of the through hole 60 provided in the lower core 54. Each of the upper bearing 62 and the lower bearing 64 is a sliding bearing made of a cylindrical metal member or a resin member. The above-described armature shaft 36 is held by an upper bearing 62 and a lower bearing 64 so as to be slidable in the axial direction.

The upper core 50 and the lower core 54 are
The upper head 16 is fitted in the cylindrical portion 46 so that a predetermined space is secured between the two. The above-described adjusting bolt 42 is in a state where the exciting current is not supplied to any of the upper coil 48 and the lower coil 52.
The armature 44 is adjusted by the upper spring 40 and the lower spring 34 and the like so as to be held at the center of the center between the upper core 50 and the lower core 54.

In the electromagnetically driven valve 10, the armature 44
Is in contact with the upper core 50, the valve body 24 is seated on the valve seat 22. In this state, the upper coil 4
8 is maintained by supplying the predetermined exciting current. Hereinafter, the state where the valve body 24 is seated on the valve seat 22 is referred to as a fully closed (valve closed) state, and the position of the valve body 24 at that time is referred to as a fully closed position. FIG. 1 shows the state of the electromagnetically driven valve 10 when the valve body 24 is fully closed.

Between the valve shaft 26 and the armature shaft 36, a buffer mechanism 66, which is a main part of the present embodiment, is provided. FIG. 2 is a cross-sectional view of the buffer mechanism 66 when the valve body 24 is fully closed. As shown in FIG.
6 comprises a buffer spring 68 and a cylindrical preset housing 70. Buffer spring 68
Is provided inside the preset housing 70. The valve shaft 2 is provided on both end surfaces of the preset housing 70.
6, and a through hole 72 having a diameter R2 slightly larger than the outer diameter R1 of the armature shaft 36 is formed. The inner diameter R3 of the buffer spring 68 is
2 is formed to be smaller than the diameter R2.
The preset housing 70 is configured such that the upper end and the lower end of the buffer spring 68 are locked to the end portion 74, thereby reducing the length of the buffer spring 68 by a predetermined length L shorter than the natural length L0.
It is regulated to 1.

Projections 76 and 77 are formed at the upper end of the valve shaft 26 and the lower end of the armature shaft 36, respectively. The protrusions 76 and 77 are provided with a buffer spring 68.
Has the role of preventing the position shift. The portions around the projections 76 and 77 on the upper end surface of the valve shaft 26 and the lower end surface of the armature shaft 36 are outer edge portions 78 and 79, respectively.
Is composed. When the valve body 24 is in the fully closed state, the inner edge of the lower end of the buffer spring 68 is in contact with the outer edge 78 formed at the upper end of the valve shaft 26. At this time, the buffer spring 6
8 and the outer edge 79 of the lower end of the armature shaft 36
, A minute clearance C1 is formed.

Next, the operation of the electromagnetically driven valve 10 will be described with reference to FIGS. First, when the exciting current supplied to the upper coil 48 is interrupted while the valve element 24 is maintained at the fully closed position shown in FIG.
The electromagnetic force acting on 4 disappears. When the electromagnetic force acting on the armature 44 disappears, the upper spring 4
By being urged to zero, the armature shaft 36 and the armature 44 are displaced downward in FIG. Then, when a suitable exciting current is supplied to the lower coil 52 at the time when the displacement amount of the armature 44 reaches a predetermined value, an attraction force for attracting the armature 44 to the lower core 54 side is generated. The armature 44
And the armature shaft 36 is further displaced downward.

When the amount of displacement reaches the clearance C1 while the armature shaft 36 is displaced downward,
The outer edge 79 at the lower end of the armature shaft 36 contacts the inner edge at the upper end of the buffer spring 68 in the buffer mechanism 66 shown in FIG. Then, the armature shaft 36 is displaced downward while pressing the buffer spring 68, and compresses the buffer spring 68 until the windings are brought into close contact.

FIG. 3 is a view showing a state of the buffer mechanism 66 when the buffer spring 68 is compressed by the armature shaft 36 until it comes into close contact. As shown in FIG. 3, when the buffer spring 68 is brought into close contact, a clearance C2 is formed between the projection 77 at the lower end of the armature shaft 36 and the projection 76 at the upper end of the valve shaft 26. When the buffer spring 68 comes into close contact, it cannot contract any further. Therefore, thereafter, the downward displacement of the armature shaft 36 is caused by the buffer spring 68
And transmitted directly to the valve shaft 26. As a result, the valve 2
4 is displaced downward in FIG. 1 with the displacement of the armature 44 and the armature shaft 36 against the urging force of the lower spring 34 while maintaining the clearance C2.

As described above, the lower end of the armature shaft 36 does not directly contact the upper end of the valve shaft 26 when the valve body 24 is driven to open the valve, and the valve shaft 26 maintains the clearance C2 between the valve shaft 24 and the armature shaft 36. The valve is displaced in the valve opening direction in a state where the valve is opened. Therefore, the electromagnetically driven valve 10 does not generate a collision sound due to the direct contact between the armature shaft 36 and the valve shaft 26. Therefore, according to the present embodiment, the electromagnetically driven valve 10
Operating noise is reduced.

The downward displacement of the valve element 24 is caused by the armature 4
4 is continued until it comes into contact with the lower core 54. When the armature 44 is in contact with the lower core 54, the valve 2
4 is located farthest from the valve seat 22. Hereinafter, the armature 44 comes into contact with the lower core 54 and the valve body 2
The state in which the valve 4 is farthest from the valve seat 22 is referred to as a fully open state, and the position of the valve body 24 at that time is referred to as a fully open position. This fully open state is maintained by supplying a predetermined exciting current to the lower coil 52.

When the exciting current supplied to the lower coil 52 is interrupted while the valve body 24 is maintained at the fully open position, the electromagnetic force acting on the armature 44 disappears. When the electromagnetic force acting on the armature 44 disappears, the valve body 24 is displaced upward in FIG. 1 by the urging force of the lower spring 34. At this time, the armature shaft 36 and the armature 44 are also
By being pressed by the valve shaft 26 via the valve shaft 8, it is displaced upward. Then, when an appropriate exciting current is supplied to the upper coil 48 when the displacement amount of the armature 44 reaches a predetermined value, an attractive force for attracting the armature 44 to the upper coil 48 side is generated.

When the above-mentioned suction force acts on the armature 44, the armature shaft 36 and the armature 44
Is further displaced upward in FIG. 1 against the biasing force of the upper spring 40. At this time, the upward displacement of the valve body 24 is continued until the valve body 24 is seated on the valve seat 22 to be in the fully closed state. After the valve body 24 is fully closed, the buffer spring 68 in the close contact state
Is gradually extended with the upward displacement of the armature shaft 36 until the length reaches the length L1 regulated by the preset housing 70. Even after the length of the buffer spring 68 becomes L1, the armature shaft 36 and the armature 44
Is further displaced upward, so that the armature shaft 36
A clearance is formed between the outer edge 79 at the lower end and the upper end of the buffer spring 68. This clearance is maintained until the armature 44 contacts the upper core 50 and the upward displacement of the armature shaft 36 and the armature 44 ends, that is, the clearance C shown in FIG.
Expand until it becomes 1.

As described above, according to the electromagnetically driven valve 10,
By supplying a predetermined excitation current to the upper coil 48, the valve element 24 can be displaced toward the fully closed position, and by supplying a predetermined excitation current to the lower coil 52, the valve element 24 can be fully opened. Can be displaced. Therefore, according to the electromagnetically driven valve 10, by supplying the exciting current to the upper coil 48 and the lower coil 52 alternately, the valve element 24 can be repeatedly reciprocated between the fully open position and the fully closed position. .

As described above, in the electromagnetically driven valve 10 of this embodiment, when the valve body 24 is fully closed, the outer edge 79 at the lower end of the armature shaft 36 and the upper end of the buffer spring 68 in the buffer mechanism 66 are connected. A minute clearance C1 is formed therebetween. For this reason, the buffer spring 68 is
No urging force in the valve opening direction is applied to the valve body 24, and only the urging force of the lower spring 34 is applied to the valve element 24, so that a decrease in the valve closing force is prevented. Therefore, according to the present embodiment, the valve element 2
4 is reliably maintained in the fully closed state.

In this embodiment, when the valve seat 22 is worn, the lower spring 34 displaces the valve shaft 26 upward, that is, in a direction in which the clearance C1 is reduced, in accordance with the amount of wear. Adhere.
Therefore, according to the present embodiment, even if the valve seat 22 is worn, the valve body 24 is reliably brought into the fully closed state. By the way, the armature 44 attracted by the upper coil 48 and displaced upward may rebound when abutting on the lower surface of the upper core 50. In the electromagnetically driven valve 10 of the present embodiment, the outer edge 79 at the lower end of the armature shaft 36
6 between the upper end of the buffer spring 68 and the clearance C
1 is formed, and if the displacement amount of the armature 44 at the time of rebound is less than C1, the armature shaft 36
Does not contact the buffer spring 68. Further, even if the amount of displacement at the time of rebound of the armature 44 is C1 or more, the rebound of the armature 44 is buffered by the buffer spring 68. For this reason, unnecessary opening operation of the valve element 24 due to the rebound of the armature 44 during the valve closing drive is prevented.

As described above, according to the present embodiment, the valve element 24 is reliably fully closed at the time of valve closing drive, and unnecessary valve opening operation of the valve element 24 is prevented. If necessary, the occurrence of the so-called gas blow-through phenomenon, which blows from the combustion chamber 20 to the exhaust port through the gap between the valve body 24 and the valve seat 22, is reliably prevented. Further, in the present embodiment, the armature shaft 36 and the valve shaft 26
8 and 8 indirectly contact each other. In particular, the valve element 2
4 when fully closed, the armature shaft 36 and the valve shaft 2
No. 6 is separated by the clearance C1 and becomes non-contact. Therefore, transmission of high heat generated due to combustion of the air-fuel mixture in the combustion chamber 20 from the valve body 24 side to the armature shaft 36 side is suppressed. Therefore, according to the present embodiment, the upper bearing 58 that slidably holds the armature shaft 36 and the lower bearing 64 are prevented from being damaged by high heat.

In the above embodiment, the upper coil 48 and the lower coil 52 correspond to the "electromagnetic coil" described in the claims, and the lower spring 34 and the upper spring 40 correspond to the "biasing member" described in the claims. The buffer spring 68 corresponds to the “elastic body” described in the claims. Also, the clearance C1 shown in FIG.
Corresponds to the "clearance" described in the claims,
The preset housing 70 corresponds to a “regulator” described in the claims.

[0030]

As described above, according to the first aspect of the present invention,
The elastic body prevents the valve body from opening due to the rebound of the armature during the valve closing drive. Further, in the present invention, since the predetermined clearance is formed between the armature shaft and the elastic body, the elastic body does not apply the urging force in the valve-opening direction to the valve body in the fully closed state, and the elastic body does not apply the urging force to the valve body. A decrease in valve closing force is prevented. Therefore, according to the present invention, the valve element can be reliably maintained in the fully closed state.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an electromagnetically driven valve according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the buffer mechanism 66 when the valve body 24 is in a fully closed state.

FIG. 3 shows the cushioning mechanism 6 when the cushioning spring 68 is compressed by the armature shaft 36 until the cushioning spring 68 comes into close contact.
FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Electromagnetic drive valve 12 Internal combustion engine 24 Valve element 26 Valve shaft 34 Lower spring 40 Upper spring 36 Armature shaft 44 Armature 48 Upper coil 50 Upper core 52 Lower coil 54 Lower core 56 ECU 66 Buffer mechanism 68 Buffer spring 70 Preset housing

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tatsuo Iida 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Hiroyuki Hattori 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F Term (reference) 3H106 DA07 DA25 DB02 DB12 DB26 DB32 DC02 DC17 DD07 EE19 EE20 GC10 KK17

Claims (1)

[Claims] An armature driven by cooperation of an electromagnetic force of an electromagnetic coil and an urging force of an urging member; an armature shaft extending in an axial direction of the armature;
An electromagnetically driven valve comprising: a valve body disposed coaxially spaced from the armature shaft; and an elastic body interposed in the space between the valve body and the armature shaft. When the body is fully closed, a predetermined clearance is formed between the armature shaft and the elastic body,
An electromagnetically driven valve having a regulating means for regulating an axial length of the elastic body to a predetermined length shorter than a natural length.