JP2000303809A - Electromagnetic driven valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power required for opening an exhaust valve in an electromagnetic driven valve, which has a valve element functioning as the exhaust valve of an internal combustion engine. SOLUTION: In an electromagnetic driven valve, a zero-rush adjuster 40 is arranged between an exhaust valve 12 and an armature shaft 42. The zero- rush adjuster 40 is extended by supplying hydraulic pressure in the case that the electromagnetic driving valve 10 is closed, for preventing generation of a clearance between the exhaust valve 12 and the armature shaft 42. The neutral position of an armature 56 is shifted to the side of a lower core 64, by reducing the hydraulic pressure supplied to the zero-rush adjuster 40 according to increase of inner cylinder pressure Pc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electromagnetically driven valve, and more particularly, to an electromagnetically driven valve suitable for driving an exhaust valve of an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Laid-Open No. 7-33204
The electromagnetically driven valve disclosed in Japanese Patent Publication No. 4 is known. The electromagnetically driven valve has a valve body that functions as an intake valve or an exhaust valve of an internal combustion engine, an armature that works with the valve body, and a pair of electromagnetic force that applies electromagnetic force in the valve opening direction and the valve closing direction of the valve body to the armature. And an electromagnet. Therefore, according to the above-mentioned conventional electromagnetically driven valve, the valve element can be opened and closed by exciting each electromagnet alternately.

[0003]

By the way, the exhaust valve of the internal combustion engine is opened when the in-cylinder pressure near the end of the combustion stroke is large. For this reason, when the exhaust valve is driven by the above-described conventional electromagnetically driven valve, it is necessary to open the exhaust valve against such a large in-cylinder pressure, and the power required to open the exhaust valve increases.

[0004] The present invention has been made in view of the above points, and an object of the present invention is to provide an electromagnetically driven valve capable of reducing the power consumption required to open an exhaust valve.

[0005]

The above object is achieved by the present invention.
As described in the above, a valve body that functions as an exhaust valve of an internal combustion engine, an armature that cooperates with the valve body, an electromagnet that attracts the armature at least in a valve opening direction, and an interposition between the valve body and the armature. A zero-rush adjuster that is mounted and extended by following a change in the distance between the valve element and the armature by applying hydraulic pressure, and a cylinder for detecting or estimating the in-cylinder pressure of the internal combustion engine. This is achieved by an electromagnetically driven valve that includes an internal pressure detection and estimation unit and a hydraulic pressure changing unit that changes a hydraulic pressure applied to the zero lash adjuster based on the in-cylinder pressure.

According to the first aspect of the present invention, the zero lash adjuster is extended by following the change in the distance between the valve body and the armature when hydraulic pressure is applied. Therefore, when the hydraulic pressure applied to the zero lash adjuster is insufficient, the zero lash adjuster does not extend sufficiently. In this case, as the neutral position of the armature shifts to the valve opening side, the distance between the armature and the electromagnet that attracts the armature in the valve opening direction decreases, and the electromagnetic force acting on the armature in the valve opening direction increases. I do. Incidentally, when the exhaust valve is opened, a high in-cylinder pressure of the internal combustion engine acts in a direction that hinders displacement in the valve opening direction. Therefore, according to the present invention, by changing the hydraulic pressure applied to the zero-lash adjuster based on the in-cylinder pressure, the exhaust valve can be opened against the in-cylinder pressure without increasing the amount of electricity to the electromagnet. Can be.

[0007]

FIG. 1 shows the configuration of an electromagnetically driven valve 10 according to an embodiment of the present invention. As shown in FIG. 1, the electromagnetically driven valve 10 includes a valve body that functions as an exhaust valve 12 or an intake valve 13 of an internal combustion engine. Exhaust valve 12 and intake valve 13
Is disposed on the lower head 16 so as to be exposed inside the combustion chamber 14 of the internal combustion engine. An exhaust port 18 and an intake port 19 are formed in the lower head 16. Valve seats 20 for the exhaust valve 12 and the intake valve 13 are formed at openings of the exhaust port 18 and the intake port 19 to the combustion chamber 14, respectively. The exhaust port 18 and the intake port 19 are respectively connected to the exhaust valve 12 and the intake valve 13 by the valve seat 2.
By communicating with the combustion chamber 14 by being away from 0,
The exhaust valve 12 and the intake valve 13 are shut off from the combustion chamber 14 by sitting on the valve seat 20.

A cylinder head spacer 24 is disposed above the lower head 16 via a heat insulating plate 22. The heat insulating plate 22 is a sheet-like member made of a heat insulating material such as bakelite, for example.
4 has a function of suppressing transmission of high heat generated from the lower head 16 to the cylinder head spacer 24. Above the cylinder head spacer 24, an upper head 25 is fixed. The electromagnetically driven valve 10 that drives the exhaust valve 12 and the electromagnetically driven valve 10 that drives the intake valve 13 have the same configuration. In the following,
The electromagnetically driven valve 10 corresponding to the exhaust valve 12 will be described.

As shown in FIG. 1, the exhaust valve 12 is integrally provided with a valve shaft 26 extending upward. The valve shaft 26 is held by a valve guide 28 so as to be slidable in the axial direction. The valve guide 28 is held by the lower head 16. A spring holding space 30 formed in a cylindrical shape is provided in a portion surrounding substantially the upper half of the valve shaft 26 of the lower head 16. The upper end of the valve guide 28 is exposed inside the spring holding space 30. A valve stem seal 31 is mounted around the upper end of the valve guide 28 in the spring holding space 30. A cotter 32 is mounted near the upper end of the valve shaft 26. Cotter 3
A lower retainer 34 is fitted around the outer periphery of the second member 2.

A spring seat 36 is provided on the bottom surface of the spring holding space 30. Spring seat 3
Between the lower retainer 6 and the lower retainer 34, a lower spring 38 that generates an urging force in a direction for separating the lower retainer 34 and the lower retainer 34 is disposed. The lower spring 38 urges the exhaust valve 12 upward through the lower retainer 34, that is, in a direction toward the valve seat 20.

An armature shaft 42 is provided above the valve shaft 26 with a zero lash adjuster 40 therebetween.
And are arranged coaxially. Zero lash adjuster 40
Will be described later in detail. A cotter 44 is mounted on the upper end of the armature shaft 42.
An applicator 46 is fitted around the cotter 44. The lower end of an upper spring 48 is in contact with the upper surface of the upper retainer 46. Upper spring 4
A cylindrical upper case 50 is provided around the periphery of the upper case 8. An adjuster bolt 5 is provided on the upper part of the upper case 50.
2 is screwed. The upper end of the upper spring 48 is in contact with the adjuster bolt 52 via a spring guide 54. The upper spring 48 urges the armature shaft 42 downward through the upper retainer 46.

An armature 56 is joined to an outer periphery of a central portion of the armature shaft 42 in the axial direction. The armature 56 is a disk-shaped member made of a soft magnetic material. Above the armature 56, an upper coil 58 and an upper core 60 are provided. Also, armature 56
The lower coil 62 and the lower core 64 are disposed below the lower side. The upper coil 58 and the lower coil 62 are accommodated in annular grooves 60a and 64a formed in the upper core 60 and the lower core 64, respectively.

The upper coil 58 and the lower coil 62 are electrically connected to a drive circuit 65. Drive circuit 65
Supplies a command signal corresponding to a control signal provided from the ECU 11 to the upper coil 58 and the lower coil 62, respectively. The upper core 60 and the lower core 64 are respectively
It has through holes 60b and 64b penetrating the central part. An upper bush 66 is provided at the upper end of the through hole 60b of the upper core 60. Further, a lower bush 68 is disposed at a lower end of the through hole 64b of the lower core 64. The armature shaft 42 is held by an upper bush 66 and a lower bush 68 so as to be slidable in the axial direction. Further, the upper end of the upper core 60 and the lower core 6
4 have flange portions 60c and 64, respectively.
c is provided.

The cylinder head spacer 24 has a cylindrical lash adjuster holding space 24 penetrating therethrough.
a is formed coaxially with the spring holding space 30. Inside the lash adjuster holding space 24a,
The above-mentioned zero lash adjuster 40 is held. A protruding portion 24b that protrudes upward is provided near the opening of the lash adjuster holding space 24a on the upper surface of the cylinder head spacer 24.

In the upper head 25, a cylindrical core holding space 25a penetrating the upper and lower portions thereof is formed coaxially with the spring holding space 30 and the lash adjuster holding space 24a. The upper core 60 has its flange 6
The lower core 64 is inserted into the core holding space 25a such that the lower core 64 abuts the upper head 25 from below through the shim 70, and the flange portion 64c abuts the upper head 25 from below. The flange portion 60c of the upper core 60 is sandwiched between the upper head 25 and a flange portion 50a formed at the lower end of the upper case 50. Also, the flange portion 64 of the lower core 64
c is sandwiched between the upper head 25 and the lower bracket 72. By fixing the upper case 50 and the lower bracket 72 to the upper head 25 with fixing bolts 74 and 76, the upper core 60 and the lower core 64 are fixed at a predetermined interval.

The cylinder head spacer 24 is provided with oil supply passages 80 and 82 which communicate with each other. The oil supply passage 82 opens at a predetermined position on the inner wall surface of the lash adjuster holding space 24a. A hydraulic pump 86 is connected to the oil supply path 80 via a hydraulic pipe 87. In this embodiment, the hydraulic pump 86 is configured as an electric pump. A regulator 88 is provided in the hydraulic pipe 87. The regulator 88 adjusts the pressure of the oil pumped from the oil tank 89 by the hydraulic pump 86 to a hydraulic pressure according to a control signal supplied from the ECU 11 and controls the oil supply path 8.
0, 82. Hereinafter, the oil pressure supplied to the oil supply paths 80 and 82 is referred to as a supply oil pressure Pe. A hydraulic pressure sensor 91 is provided downstream of the regulator 88 of the hydraulic pressure pipe 87. The oil pressure sensor 91 outputs an electric signal corresponding to the supply oil pressure Pe to the ECU 11. The ECU 11 detects the supply oil pressure Pe based on the output signal of the oil pressure sensor 91. In the present embodiment, the above-described hydraulic supply system includes:
The electromagnetically driven valve 10 that drives the exhaust valve 12 and the electromagnetically driven valve 10 that drives the intake valve 13 are provided independently of each other.

The cylinder head spacer 24 further includes
An oil recovery hole 90 is provided. The oil recovery hole 90 vertically penetrates the cylinder head spacer 24 so that the upper end is opened near the raised portion 24 b of the cylinder head 24 and the lower end is opened into the spring holding space 30. The oil recovery hole 90 collects oil leaking upward from the zero lash adjuster 40 and flows the oil into the spring holding space 30, and this oil is supplied to the armature shaft 42 and the valve shaft 26.
It has the role of serving as a lubricating oil. Since the upper portion of the oil recovery hole 90 is formed by the processing holes 90a and 90b, a large opening area of the oil recovery hole 90 on the upper surface of the cylinder head spacer 24 is ensured.

An intake passage 92 is connected to the intake port 19. A throttle valve 93 is provided in the intake passage 92. Air is drawn into the intake passage 92 in an amount corresponding to the opening of the throttle valve 93. An intake pressure sensor 94 is provided downstream of the throttle valve 93 in the intake passage 92. The intake pressure sensor 94 outputs an electric signal corresponding to the pressure in the intake passage 92 (hereinafter, referred to as intake pressure PM) to the ECU.
Output to 11. The ECU 11 controls the intake pressure sensor 9
4, the intake pressure PM is detected.

On the other hand, the exhaust port 18 has an exhaust passage 96.
Is connected. Exhaust gas discharged from the combustion chamber 14 in the exhaust stroke of the internal combustion engine is discharged from the exhaust passage 96 to the outside through a catalyst and a muffler (not shown). ECU 11
Is also electrically connected to a rotation speed sensor 98. The rotation speed sensor 98 outputs an electric signal corresponding to the rotation speed of the internal combustion engine (hereinafter, referred to as engine rotation speed NE) to the ECU 11. The ECU 11 detects the engine speed NE based on the output signal of the speed sensor 98.

Next, the operation of the electromagnetically driven valve 10 will be described. When a current is supplied to the upper coil 58, an electromagnetic force in a direction toward the upper core 60 acts on the armature 56 by the magnetic flux generated by the upper coil 58. Therefore, as shown in FIG. 1, the armature 56 is displaced until it comes into contact with the upper core 60 against the urging force of the upper spring 48. Hereinafter, the position where the armature 56 contacts the upper core 60 will be referred to as the armature 56 or the exhaust valve 1.
2 is referred to as a fully closed position. In this state, the exhaust valve 12 is seated on the valve seat 20, and the exhaust valve 12 is closed.

When the supply of current to the upper coil 58 is stopped in the state where the exhaust valve 12 is closed,
The electromagnetic force required to hold the armature 56 in the fully closed position disappears. Therefore, when the supply of the current to the upper coil 58 is stopped, the armature 56 is urged by the upper spring 48 together with the exhaust valve 12 to start a single-vibration movement downward. Therefore, the exhaust valve 1
When the valve 2 is separated from the valve seat 20, the exhaust valve 12 is opened. When the exciting current is supplied to the lower coil 62 when the displacement amount of the armature 56 reaches a predetermined value, the armature 5
An electromagnetic force for driving the motor 6 toward the lower core 64 is generated.

When the above-mentioned electromagnetic force acts on the armature 56, the kinetic energy lost by friction is compensated,
The armature 56 is displaced against the urging force generated by the lower spring 38 until it contacts the lower core 64. Hereinafter, the position where the armature 56 contacts the lower core 64 is referred to as the armature 56 or the fully opened position of the exhaust valve 12. In this state, when the supply of the exciting current to the lower coil 62 is stopped, the electromagnetic force required to hold the armature 56 at the fully open position disappears. Therefore, the exhaust valve 12 and the armature 56 start a single-vibration motion upward by the urging force generated by the lower spring 38. When an exciting current is supplied to the upper coil 58 when these displacement amounts reach a predetermined value, the kinetic energy lost due to friction is compensated by the electromagnetic force generated by the upper coil 58, and the armature 5
6 is displaced until it comes into contact with the upper core 60. When the armature 56 is in contact with the upper core 60, the exhaust valve 1
When 2 is seated on the valve seat 20, the exhaust valve 12 is closed again.

As described above, according to the present embodiment, the current is alternately supplied to the upper coil 58 and the lower coil 62 at an appropriate timing, so that the armature 56 and the exhaust valve 12 are switched between the fully closed position and the fully open position. Can be reciprocated repeatedly. In a state where neither the upper coil 58 nor the lower coil 62 is energized, the armature 56 is held at an intermediate position between the upper core 60 and the lower core 64 by the upper spring 48 and the lower coil 38. Hereinafter, the position of the armature 56 in such a state is referred to as a neutral position of the armature 56.

In the present embodiment, the above-mentioned zero lash adjuster 40 is provided between the exhaust valve 12 and the armature shaft due to the difference in thermal expansion between the exhaust valve 12 and the lower head 16 and the wear of the seating surface between the exhaust valve 12 and the valve seat 20. It has a function of preventing a gap from being formed between both members by absorbing the relative displacement with respect to. Hereinafter, the configuration and operation of the zero lash adjuster 40 will be described.

FIG. 2 is an enlarged sectional view showing the zero lash adjuster 40 and its peripheral portion. In addition, FIG.
This shows a state realized under a situation where the armature 56 and the exhaust valve 12 are in the fully closed position. As shown in FIG. 2, the zero lash adjuster 40 includes a plunger body 100. The plunger body 100 is slidably disposed in the lash adjuster holding space 24a in the axial direction. The plunger body 100 is a substantially cylindrical member whose one end (the lower end in FIG. 2) is closed. The plunger body 100 includes a spring holding portion 100a provided at a lower end thereof, and a plunger holding portion 100b having a larger diameter than the spring holding portion 100a.

A plunger 102 is provided on the plunger holding portion 100b of the plunger body 100 so as to be slidable in the axial direction. A hydraulic chamber 104 is defined between the lower bottom surface of the plunger 102 in FIG. 2 and the lower bottom surface of the spring holding portion 100a. Plunger 102
Has a large-diameter portion 102a that slides on the outer peripheral surface of the plunger holding portion 100b and a small-diameter portion 102b provided at the upper end in FIG. on the other hand,
A stopper ring 106 is press-fitted into the upper end of the inner peripheral surface of the plunger accommodating portion 100b. Stopper ring 10
6 has an inner diameter smaller than the outer diameter of the large diameter portion 102a of the plunger 102. Therefore, the plunger 102
The upward displacement inside the plunger holding portion 100b is caused by a step between the large diameter portion 102a and the small diameter portion 102b,
It is regulated by contact with the stopper ring 106. The plunger 102 also has a reservoir chamber 108 that opens upward, and the reservoir chamber 108 and the hydraulic chamber 1
The communication passage 110 communicates with the communication passage 04.

In the hydraulic chamber 104, a retainer 112 and a plunger spring 114 are provided. The plunger spring 114 urges the plunger 102 upward via the retainer 112. A check ball 116 and a check ball spring 118 are provided inside the retainer 112. The check ball spring 118 urges the check ball 116 toward the opening of the communication passage 110. The check ball 116 and the check ball spring 118 function as a check valve that opens only when the pressure in the hydraulic chamber 104 becomes lower than that in the reservoir chamber 108.

The zero lash adjuster 40 also has a reservoir cap 120. The reservoir cap 120 is a cylindrical member having one end (the lower end in FIG. 2) closed. The reservoir cap 120 is slidably disposed in the lash adjuster holding space 24a such that the outer bottom surface is in contact with the upper end surface of the plunger 102. On the lower bottom surface of the reservoir cap 120, an overflow recess 122, which is partially cut away, is provided. The overflow recess 122 is located in the reservoir 1
08 is always in communication.

The lower end surface of the armature shaft 42 is in contact with the inner bottom surface of the reservoir cap 120. on the other hand,
The upper end surface of the valve shaft 26 is in contact with the outer bottom surface of the plunger body 100. In addition, the oil supply passage 82 has an inner peripheral surface of the lash adjuster holding space 24a that communicates with the overflow recess 122 in a state shown in FIG. 2 (that is, a state in which the armature 56 and the exhaust valve 12 are in the fully closed position). It is open to.

In the state shown in FIG.
When the power supply to the armature shaft 42 is cut off, the urging force in the valve opening direction acts on the armature shaft 42 as described above. The force in the valve opening direction is applied from the reservoir cap 120 to the plunger 102.
Is transmitted to When the force transmitted to the plunger 102 exceeds the urging force of the plunger spring 114, the plunger 102 is pressed downward, so that the oil in the hydraulic chamber 104 is pressurized. Therefore, the hydraulic pressure in the hydraulic chamber 104 becomes higher than the hydraulic pressure in the reservoir chamber 108, and the communication passage 11
0 is closed by the check ball 116. Communication passage 1
10 is closed, the hydraulic chamber 104 and the reservoir chamber 108
The transfer of oil between is prohibited. Therefore, the driving force transmitted to the plunger 102 is transmitted to the plunger body 100 via the hydraulic chamber 104, and the zero lash adjuster 40 is displaced in the valve opening direction together with the armature shaft 42 and the exhaust valve 12. When the zero lash adjuster 40 is displaced in the valve opening direction, the oil in the hydraulic chamber 104 is pressurized, so that the plunger 102 and the plunger body 1 are displaced.
The oil gradually leaks from the hydraulic chamber 104 through the sliding surface with the hydraulic fluid 00, and the lash adjuster 40 contracts by a small amount corresponding to the amount of the leaked oil.

After the armature 56 has been displaced until it comes into contact with the lower core 64, when the energization of the lower coil 62 is stopped, the armature 56 starts to be displaced in the valve closing direction. When the exhaust valve 12 is seated on the valve seat 20, the urging force of the lower spring 38 does not act on the plunger body 100. On the other hand, even after the exhaust valve 12 is seated on the valve seat 20, the armature 56 is further displaced in the valve closing direction by a minute amount corresponding to the contraction of the lash adjuster 40 in the process of displacing the exhaust valve 12 in the valve opening direction. I do. In this case, the plunger 102 tries to slide upward with respect to the plunger body 100 following the reservoir cap 120 by the urging force of the plunger spring 114, and the hydraulic pressure in the hydraulic chamber 104 decreases. When the pressure in the hydraulic chamber 104 becomes lower than the pressure in the reservoir chamber 108, the check ball 116 moves away from the opening of the communication passage 110, so that the hydraulic chamber 104 and the reservoir chamber 108 communicate with each other. As described above, when the exhaust valve 12 is seated on the valve seat 20, the oil supply path 82 and the overflow recess 122 communicate with each other. Therefore, when the hydraulic chamber 104 and the reservoir chamber 108 communicate with each other, the oil of the supply hydraulic pressure Pe supplied to the oil supply path 80 flows into the hydraulic chamber 104 from the oil supply path 82 through the reservoir chamber 108, and the plunger The reference numeral 102 slides upward while maintaining the state in which it is in contact with the reservoir cap 120.

As described above, when the exhaust valve 12 reaches the fully closed position, the oil of the supply hydraulic pressure Pe is supplied to the zero lash adjuster 40, so that the zero lash adjuster 40
Of the exhaust valve 12 and the armature shaft 4
2, that is, a tappet clearance is prevented from occurring. Further, the change in the thermal expansion between the exhaust valve 12 and the lower head 16 and the change in the interval between the valve shaft 26 and the armature shaft 42 caused by the wear of the seating surface between the exhaust valve 12 and the valve seat 20 are gradual with time. The amount of change in the interval that occurs when the exhaust valve 12 makes one reciprocation between the fully closed position and the fully open position is extremely small. For this reason,
Such an interval change is absorbed in a process in which the zero lash adjuster 40 contracted while the exhaust valve 12 is open extends when the exhaust valve 12 is closed.

The state in which the zero lash adjuster 40 is extended until the tappet clearance is no longer generated,
Hereinafter, it is referred to as a zero rush state. The neutral position of the armature 56 in the zero rush state is hereinafter referred to as a neutral reference position. By the way, the exhaust valve 12 is opened near the bottom dead center where the combustion stroke ends. In the combustion stroke, combustion chamber 1
In FIG. 4, a large in-cylinder pressure Pc is generated due to combustion. Therefore, when the exhaust valve 12 is opened, the large in-cylinder pressure Pc
A force corresponding to the pressure difference between the pressure at the exhaust port 18 and the pressure at the exhaust port 18 (hereinafter, referred to as the valve opening pressure Po) acts in a direction to hinder the displacement of the exhaust valve 12. That is, in order to open the exhaust valve 12, it is necessary to apply a large electromagnetic force to the armature 56 to oppose the valve opening pressure Po.

On the other hand, as described above, the zero lash adjuster 40 extends when the oil of the supply oil pressure Pe is supplied from the oil supply passage 82 when the exhaust valve 12 reaches the vicinity of the fully closed position, so that the tappet clearance is increased. Is a mechanism for preventing the occurrence of Therefore, if the supply hydraulic pressure Pe is insufficient, even if the exhaust valve 12 reaches the fully closed position, the zero lash adjuster 40 may not be able to extend until the zero rush state is formed. In this case, the neutral position of the armature 56 is displaced from the neutral reference position toward the lower core 64 as the supply oil pressure Pe decreases. The amount of displacement of the neutral position of the armature 56 from the neutral reference position toward the lower core 64 is hereinafter referred to as a neutral shift amount L.

FIG. 3 shows the relationship between the position of the armature 56 and the electromagnetic attraction acting between the lower core 64 and the armature 56 when a constant exciting current is supplied to the lower coil 62. As shown in FIG. 3, when a constant exciting current is supplied to the lower coil 62, the electromagnetic attraction force acting between the armature 56 and the lower core 64 is
Becomes larger as the position moves toward the lower core 64 side. That is, the lower the supply oil pressure Pe, that is, the neutral shift amount L
When the constant current is supplied to the lower coil 62, the electromagnetic force acting on the armature 56 in the valve-opening direction increases as the current value increases.

The displacement of the armature 56 from the neutral position to the lower core side 64 is caused by the zero lash adjuster 40 not extending sufficiently. Therefore,
The exhaust valve 12 is displaced in the valve closing direction by the same amount as the neutral shift amount L symmetrically with the armature 56 with the zero lash adjuster 40 interposed therebetween. In this case, the exhaust valve 12
The amount of contraction deformation of the lower spring 38 when the armature reaches the fully opened position is reduced, so that the armature 5
The spring force acting on the valve 6 in the valve closing direction is also reduced. Therefore, the larger the neutral shift amount L is, the smaller the electromagnetic force to be applied to the armature 56 to hold the exhaust valve 12 at the fully open position.

As described above, as the neutral shift amount L increases, the electromagnetic force for attracting the armature 56 toward the fully closed position increases, and the electromagnetic force required to hold the exhaust valve 12 at the fully open position decreases. I do. Therefore, in the present embodiment, the valve opening pressure Po of the electromagnetically driven valve 10 for driving the exhaust valve 12 is set.
The neutral position of the armature 56 is displaced from the neutral reference position toward the lower core 64 by decreasing the supply hydraulic pressure Pe in accordance with As a result, the exhaust valve 12 can be reliably displaced to the fully open position against the valve opening pressure Po without increasing the exciting current supplied to the lower coil 62.

FIG. 4 is a flowchart of a routine executed by the ECU 11 to realize the above functions in the present embodiment. The routine shown in FIG. 4 is started at predetermined time intervals for the electromagnetically driven valve 10 that drives the exhaust valve 12. When the routine shown in FIG. 4 is started, first, the process of step 200 is executed. In step 200, the cylinder pressure Pc is estimated. In general, as the engine speed NE increases and the intake pressure PM increases, the in-cylinder pressure Pc increases. Therefore, in the present embodiment, as shown in FIG. 5, the relationship between the engine speed NE and the intake pressure PM and the in-cylinder pressure Pc is experimentally obtained in advance and stored as a map.
In step 200, the in-cylinder pressure P is determined based on the engine speed NE and the intake pressure PM by referring to the map.
Estimate c. The pressure inside the intake port 18 is always maintained at a pressure substantially equal to the atmospheric pressure. Therefore, step 2
The in-cylinder pressure Pc estimated at 00 is used as the valve opening pressure Po in the subsequent steps.

In step 202, a neutral shift amount L is determined based on the valve opening pressure Po so that the exhaust valve 12 can be driven to the fully open position without increasing the exciting current to the lower coil 62. As described above, the electromagnetic force in the valve opening direction to be applied to the armature 56 when the exhaust valve 12 is opened increases as the valve opening pressure Po increases. On the other hand, as the supply oil pressure Pe is smaller (that is, as the neutral shift amount L is larger), the electromagnetic force in the valve opening direction acting on the armature 56 when a constant exciting current is supplied to the lower coil 62 increases.
The electromagnetic force required to hold the exhaust valve 12 in the fully open position is reduced. Therefore, in the present embodiment, as shown in FIG. 6, the relationship between the valve opening pressure Po and the supply oil pressure Pe is experimentally obtained in advance and stored as a map. In step 202, the map is referred to. , The neutral shift amount L is determined.

In step 204, the supply oil pressure Pe is changed based on the control signal to the regulator 88 so that the neutral position of the armature 56 is displaced toward the lower core 64 by the neutral shift amount L determined in step 202. Can be In step 206, according to the neutral shift amount L, the upper coil 58
And the value of the exciting current supplied to the lower coil 62 (that is,
Processing is performed to change the value of a suction current for sucking the armature 56 to the fully closed position or the fully open position, and a value of a holding current for holding the armature 56 at the fully closed position or the fully open position.

The neutral position of the armature 56 is the lower core 64
When it is displaced to the side, the distance between the armature 56 and the upper core 60 increases. Therefore, as the neutral shift amount L increases, the electromagnetic force in the valve closing direction applied to the armature 56 decreases. On the other hand, when the exhaust valve 12 is closed, that is, in the vicinity of the top dead center at which the exhaust stroke ends, the in-cylinder pressure Pc has decreased to substantially the atmospheric pressure. Therefore, there is no generation of a force for driving the exhaust valve 12 in the valve closing direction or holding the exhaust valve 12 in the fully closed position by the in-cylinder pressure Pc. Therefore, as the neutral shift amount L increases, the exciting current to be supplied to the upper coil 58 increases.

The supply oil pressure Pe is changed by the processing of steps 200 to 204 so that the exhaust valve 12 can be opened without increasing the excitation current to the lower coil 62. Pe
Is not always easy to control to an optimal value such that the exciting current to the lower coil 62 is kept constant. Therefore, it may be necessary to change the exciting current to be supplied to the lower coil 62 in accordance with a decrease in the supplied oil pressure Pe.

In step 206, in consideration of these points, the exciting current to the upper coil 58 and the lower coil 62 is changed according to the supply oil pressure Pe. When the process of step 206 ends, the current routine ends. As described above, in the present embodiment, the supply oil pressure Pe is reduced in accordance with the increase in the valve opening pressure Po, so that the exhaust valve is opposed to the valve opening pressure Po without increasing the exciting current to be supplied to the lower coil 62. 12 can be reliably displaced to the fully open position. Therefore, according to the present embodiment, it is possible to reduce the electric power required to open the exhaust valve 12, thereby achieving power saving and low heat generation of the electromagnetically driven valve 10.

Further, in this embodiment, the supply hydraulic pressure Pe decreases as the in-cylinder pressure Pc increases, so that the hydraulic pump 86
Is also reduced. Therefore, according to the present embodiment, power saving of the hydraulic pump 86 can be achieved. When the supply oil pressure Pe decreases, a large tappet clearance is generated in accordance with the decrease, and the operation noise of the electromagnetically driven valve 10 increases. However, the valve opening pressure Po increases when the internal combustion engine is operating at a high speed or a high load. In such a state, the operating noise of the internal combustion engine is also high. For this reason, even if the operation sound of the electromagnetically driven valve 10 increases due to a decrease in the supply oil pressure Pe, the operation sound is hardly noticeable. Therefore,
According to the present embodiment, by setting the relationship between the valve opening pressure Po and the supply oil pressure Pe, the state where the priority is given to the reduction of the operating noise of the electromagnetically driven valve 10 and the state where the power saving of the electromagnetically driven valve 10 is prioritized. It can be realized by appropriately selecting according to the operation state.

When the supply oil pressure Pe is constant, the longer the time during which the exhaust valve 12 is held at the fully closed position (that is, the time during which the oil pressure is applied to the zero lash adjuster 40), the longer the zero lash adjuster. 40
Extend, the neutral shift amount L decreases. Exhaust valve 1
2 is held in the fully closed position, the engine speed NE
The smaller is the longer. Therefore, the neutral shift amount L can be set more accurately by correcting the supply oil pressure Pe so as to decrease as the engine speed NE increases.

In the above embodiment, the supply oil pressure Pe is continuously changed in accordance with the valve opening pressure Po. However, the present invention is not limited to this.
May be controlled by the ECU 11. That is, when the valve opening pressure Po is equal to or less than a predetermined value,
When the hydraulic pump 86 is operated, a sufficient supply oil pressure Pe for realizing the zero rush state is secured, and when the valve opening pressure Po exceeds a predetermined value, the hydraulic pump 86 is stopped to supply the oil pressure to the zero lash adjuster 40. May be stopped.

Further, in the above embodiment, the cylinder pressure Pc is estimated based on the engine speed NE and the intake pressure PM. However, the invention is not limited to this, and the cylinder pressure sensor is provided in the cylinder of the internal combustion engine. The internal pressure Pc may be directly detected. In the first embodiment, the lower coil 62
The lower core 64 corresponds to the “electromagnet” described in the claims, the armature 56 and the armature shaft 42 correspond to the “armature” described in the claims, and the ECU 11 performs the steps of the routine shown in FIG. The "in-cylinder pressure detection / estimation means" described in the claims by executing the processing in step 200 and the hydraulic pressure described in the claims by executing the processing in steps 202 and 204 of the routine shown in FIG. Means of change "
Each has been realized.

[0048]

According to the first aspect of the present invention, the electric power required to open the exhaust valve can be reduced.

[Brief description of the drawings]

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

FIG. 2 is an enlarged cross-sectional view of a zero lash adjuster included in the electromagnetically driven valve of the present embodiment and a peripheral portion thereof.

FIG. 3 is a diagram showing a relationship between a neutral position of the armature and an electromagnetic force acting between the armature and the lower core.

FIG. 4 is a flowchart of a routine executed by an ECU in the embodiment.

FIG. 5 shows an engine speed NE in the routine shown in FIG. 4;
EC to estimate in-cylinder pressure Pc based on pressure and intake pressure PM
This is a map referred to by U.

FIG. 6 is a map referred to by the ECU for determining the supply oil pressure Pe based on the valve opening pressure Po in the routine shown in FIG. 4;

[Explanation of symbols]

 Reference Signs List 10 electromagnetically driven valve 11 electronic control unit (ECU) 12 exhaust valve 40 zero lash adjuster 42 armature shaft 56 armature 62 lower coil 64 lower core

Continued on the front page (72) Inventor Isao Matsumoto 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Shoji Katsama 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Invention Person Masaaki Tanaka 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Keiji Yoeda 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation F term (reference) 3G016 AA05 AA18 CA11 CA27 CA33 CA48 CA59 DA16 DA22 EA11 EA21 3G092 AA11 DA01 DA02 DA07 DF04 DF05 DF10 DG02 DG05 DG09 EA13 EA14 FA24 FA49 HA05Z HC01Z HE00Z HE01Z 3H106 DA07 DA25 DB02 DB13 DB26 DB32 DC02 DC17 DD06 EE12 FB11 GC33

Claims (1)

[Claims] 1. A valve body functioning as an exhaust valve of an internal combustion engine, an armature interlocked with the valve body, an electromagnet for attracting the armature at least in a valve opening direction, and an interposition between the valve body and the armature. And a zero lash adjuster that extends by following a change in the distance between the valve body and the armature when hydraulic pressure is applied, wherein the cylinder detects or estimates the in-cylinder pressure of the internal combustion engine. An electromagnetically driven valve, comprising: an internal pressure detection estimating unit; and a hydraulic pressure changing unit that changes a hydraulic pressure applied to the zero lash adjuster based on the in-cylinder pressure.