JP2007154793A - Solenoid valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solenoid valve which enables easy control and reduction in size. <P>SOLUTION: A solenoid valve contains a valve 87 having a valve stem 88 and reciprocating along a direction in which the valve stem 88 extends, a disk 74 which is a magnetic member moving in conjunction with the valve 87, a first electromagnet for attracting the disk 74 to hold the disk in a valve closing position and a lower spring which is a first elastic member for adding to a magnetic member a force separating the disk 74 from the first electromagnet directed toward a neutral position from the valve closing position. The first electromagnet includes an electromagnet coil 82 and a magnetic core 78. An elastic constant of the lower spring 86 is lower when the disk 74 is in a second position where the magnetic member is closer to the neutral position than a first position as compared with the case in a first position. A coil spring with unequal pitches and a multiple spring formed by combining a plurality of coil springs can be utilized as the lower spring 86, for instance. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electromagnetically driven valve, and particularly to an electromagnetically driven valve used as an intake valve or an exhaust valve of an internal combustion engine.

  With respect to a conventional electromagnetically driven valve of an internal combustion engine, for example, Japanese Patent Laid-Open No. 2003-314232 (Patent Document 1) discloses that an excitation current is alternately supplied to upper and lower electromagnetic coils during initial driving, and a vibration amplitude of valve displacement from a neutral position. Is disclosed in which the armature is attracted to the electromagnet by gradually increasing.

In this example, in the initial state where no current flows through the coil, the valve is in a neutral position, and when the current flows, the movable plate having the narrower gap between the electromagnet and the movable plate is slightly attracted by the electromagnet. Once the current is interrupted, the valve is pushed by the valve spring in the opposite direction (for example, from the fully closed state toward the fully open state) and moves past the neutral position by inertial force. When the current is supplied again at this time, the amplitude of the movable plate is increased by the electromagnetic force, and this operation is repeated several times, so that the movable plate is finally attracted to the electromagnet and the valve open or closed state is maintained.
JP 2003-314232 A

  The electromagnetically driven valve having such a configuration can be used in combination with the elastic force of the spring and the electromagnetic force of the electromagnet to make the device more energy efficient and smaller in size than the control using only the electromagnet.

  On the other hand, in recent years, in order to simplify the power supply system, it has been studied to lower the drive voltage of the electromagnet of the electromagnetically driven valve from 42V to 12V. It is known that when the driving voltage of the electromagnet is lowered, the control response of the electromagnet current is deteriorated.

  Usually, the elastic force of the spring is proportional to the displacement of the movable plate from the neutral position, while the electromagnetic force of the electromagnet is inversely proportional to the square of the distance between the movable plate and the electromagnet. Therefore, if the electromagnet is designed to overcome the spring elastic force at all displacements, the physique of the electromagnet increases, the control responsiveness of the current flowing through the electromagnet decreases due to the increase in the number of turns of the electromagnet, There is a problem that energy efficiency deteriorates due to the increase.

  An object of the present invention is to provide an electromagnetically driven valve that is easy to control and small in size.

  In summary, the present invention is an electromagnetically driven valve that has a valve shaft and reciprocates along the direction in which the valve shaft extends, a magnetic member that moves in conjunction with the valve, and a suction member that attracts the magnetic member. A first electromagnet that is held in a predetermined position of either one of the valve opening and the valve closing; a first elastic member that applies a force to the magnetic member to move the magnetic member away from the first electromagnet from the predetermined position toward the neutral position; Is provided. The elastic constant of the first elastic member is smaller when the magnetic member is in the second position closer to the neutral position than the first position than when the magnetic member is in the first position.

Preferably, the first elastic member is an unequal pitch coil spring.
Preferably, the first elastic member is a multiple spring in which the first coil spring and the second coil spring are combined.

  Preferably, the electromagnetically driven valve causes the first electromagnet to flow to the first electromagnet so that the attraction force of the first electromagnet is larger than the elastic force of the elastic member in order to move the magnetic member from the neutral position toward the predetermined position. A control device for controlling the suction current is further provided.

  Preferably, the predetermined position is a valve opening position, and the electromagnetically driven valve applies a resilient force to the valve shaft and a second electromagnet that attracts the magnetic member and holds it in the valve closing position. And a second elastic member for applying a force to the magnetic member to separate the second electromagnet from the second electromagnet toward the neutral position.

  More preferably, the first electromagnet includes a first coil. The second electromagnet includes a second coil connected to the first coil. An equal current flows through the first and second coils.

  More preferably, the electromagnetically driven valve has a holding current required for holding the current flowing in the first and second coils as a suction current having a predetermined current value required for suction to the predetermined position and then holding the current at the predetermined position. And a control device that performs control to reduce the above.

  According to the present invention, an electromagnetically driven valve with reduced power consumption can be realized.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

FIG. 1 is a diagram showing a schematic configuration of an electromagnetically driven valve according to an embodiment of the present invention.
An engine that is an internal combustion engine includes a cylinder block, a cylinder head, a piston that moves up and down in the cylinder, an electromagnetically driven intake valve that is provided at an intake port of each cylinder, and an electromagnetically driven exhaust valve that is provided at an exhaust port of each cylinder. including. For example, two intake valves and two exhaust valves are provided for each cylinder. In FIG. 1, one electromagnetically driven valve is typically shown.

FIG. 2 is a block diagram showing a configuration related to driving and control of the electromagnetically driven valve.
Referring to FIGS. 1 and 2, a crank angle sensor 6 for detecting the engine speed is attached to a cylinder block of the engine. Various sensor outputs such as the crank angle sensor 6 are input to an electronic control unit (ECU) 30. The ECU 30 controls the injection timing and injection amount of the fuel injection valve, the ignition timing of the spark plug, and an electromagnetic drive unit ( EDU) 32 is instructed to open the intake valve or the exhaust valve.

  A power supply voltage is supplied from the DC power supply 11 to the EDU 32. Examples of the DC power supply 11 include an alternator that outputs a power supply voltage of 14 V, a 12 V battery, and the like.

  The electromagnetically driven valve of the present embodiment has a valve shaft 88, a valve 87 that reciprocates along the direction in which the valve shaft 88 extends, a disk 74 that is a magnetic member that moves in conjunction with the valve 87, and a disk 74. A first electromagnet that attracts and holds the disc 74 at the valve open position, and a lower spring 86 that is a first elastic member that applies a force to the magnetic member to move the disc 74 away from the first electromagnet from the valve open position toward the neutral position. Including. The first electromagnet includes an electromagnetic coil 82 and an electromagnetic core 78.

  As will be described in detail later, the elastic constant of the lower spring 86 is smaller when the magnetic member is in the second position closer to the neutral position than in the first position than when the disk 74 is in the first position.

  As the lower spring 86, for example, a coil spring having an unequal pitch, which will be described later, or a multiple spring in which a plurality of coil springs are combined can be used.

  The electromagnetically driven valve further directs the disk 74 from the second electromagnet to the neutral position by applying an elastic force to the valve shaft 88 and a second electromagnet that attracts the disk 74 and holds it in the closed position. And a torsion bar 68 as a second elastic member for applying a separating force to the disk 74. The second electromagnet includes an electromagnetic coil 80 and an electromagnetic core 72. The coil 80 and the coil 82 are connected, and an equal current flows through the coil 80 and the coil 82.

  The disc 74 is a swinging member that is supported at one end by the housing 62 so as to be swingable, and at the other end is provided with an action part for reciprocating the valve shaft along the direction in which the valve shaft extends.

  The electronic control unit (ECU) 30 includes a memory 31. The memory 31 stores an energization pattern corresponding to the output of the crank angle sensor 6 as a map.

  In order to move the disk 74 in the direction from the neutral position toward the valve opening position, the ECU 30 generates an attraction current flowing through the valve opening electromagnet so that the attraction force of the valve opening electromagnet is larger than the elastic force of the lower spring 86. Control. That is, the map stored in the memory 31 reflects the nonlinear elastic constant of the lower spring 86.

  The ECU 30 performs control to reduce the current flowing through the coils 80 and 82 to a holding current necessary for holding the valve at the valve opening position after the current flowing through the coils 80 and 82 is set to a predetermined current value necessary for the valve opening position during the initial driving. Do.

  The valve 87 moves up and down to open and close an intake port or an exhaust port provided in the cylinder head 10. An intermediate stem 76 is provided on the upper portion of the valve shaft 88 extending upward from the valve 87. A cam follower pin is attached to the upper end of the intermediate stem 76. The cam follower pin abuts against the acting portion at the other end opposite to the one end that is swingably supported by the housing 62 of the disk 74. As the disk 74 swings, the valve 87 reciprocates along the direction in which the valve shaft 88 extends.

  A stroke ball bearing 89 is provided between the valve shaft 88 and the cylinder head 10, and the valve shaft 88 is supported movably in the vertical direction. A retainer 84 is provided below the intermediate stem 76. A lower spring 86 is disposed between the retainer 84 and the cylinder head 10 around the valve shaft 88.

  The electromagnetic actuator for reciprocating the intermediate stem 76 includes a valve opening electromagnet and a valve closing electromagnet fixed to the housing 62. The valve opening electromagnet includes a valve opening electromagnetic core 78 and a coil 82. The valve closing electromagnet includes a valve closing electromagnetic core 72 and a coil 80. The coil 80 and the coil 82 have a monocoil structure that is connected and shared. In addition, you may control the electric current of the coil 80 and the coil 82 by EDU32 separately without using a monocoil structure. The disk 74 is alternately adsorbed by these opening and closing electromagnets.

  The disk 74 applies a downward force, that is, a valve opening direction force to the intermediate stem 76 by the elastic force of the torsion bar 68 that is an upper spring that forms a pair with the lower spring 86. The other end of the disk 74 abuts on a cam follower pin fixed to the upper end of the intermediate stem 76, and applies a downward force, that is, a valve opening direction force to the intermediate stem 76.

  On the contrary, the lower spring 86 pushes up the retainer 84 to apply an upward force, that is, a valve closing direction force to the intermediate stem 76.

  As a resultant force of the torsion bar 68 and the lower spring 86, a force is generated in the opening direction when the valve 87 is fully closed, and conversely, a force is generated in the closing direction when the valve 87 is fully opened. When the distance between the disk 74 and the coil of the electromagnet to be attracted is large and the electromagnetic force to attract the disk 74 is weak, the size of the electromagnet can be reduced by using the elastic force of this spring.

FIG. 3 is a view showing an example of the lower spring 86 of FIG.
Referring to FIG. 3, the lower spring 86 is a coil spring through which the valve shaft 88 passes through the center, and has one end in contact with the retainer 84 and the other end in contact with the cylinder head 10.

  The retainer 84 is fixed to the valve shaft 88 with a valve cotter. When the disc 74 is attracted by the valve opening electromagnet and the valve shaft 88 is displaced from the neutral position toward the valve opening position, the lower spring 86 is compressed and generates an elastic force that pushes up the valve shaft.

  Here, the lower spring 86 is an unequal pitch spring, and has a portion where the pitch is P1 and a portion where the pitch is P2 smaller than P1.

  FIG. 4 is a diagram showing the relationship between the elastic force of the lower spring 86 and the electromagnetic force of the valve opening electromagnet.

  Referring to FIG. 4, the horizontal axis indicates the lift amount D (mm), and the vertical axis indicates the force F (N). Further, the spring force Fs0 when a normal spring is used is indicated by a broken line, and the spring force Fs1 of an unequal pitch spring as shown in FIG. 3 is indicated by a solid line. Moreover, the electromagnetic force Fm by the electromagnet for valve opening is shown by the thick line.

When the lift amount is in the neutral position, the spring forces Fs0 and Fs1 are both zero.
First, the elastic constant of a normal spring is uniform, and the spring force Fs0 is proportional to the lift amount D, that is, the displacement from the neutral position.

  On the other hand, the electromagnetic force Fm is not zero at the neutral position. The electromagnetic force is inversely proportional to the square of the distance of the disk from the electromagnet. Since the distance of the disk from the electromagnet decreases as the lift amount D increases, the gradient of increase of the electromagnetic force Fm is smaller than the gradient of the spring force Fs0 near the neutral point, but when the lift amount D increases, the electromagnetic force Fm increases. The inclination is larger than the inclination of the electromagnetic force Fs0.

  When the electromagnetic force Fm and the spring force Fs0 are in the relationship shown in FIG. 4, the spring force Fs0 is larger than the electromagnetic force Fm in the range of lift amounts D1 to D3, so that the valve is stationary at the neutral position. It is difficult to move the valve from the present state to the open state at once. For this reason, it is necessary to vibrate the valve to pass the range of the lift amounts D1 to D3 by the inertial force, and the control of the initial driving operation becomes complicated.

  Further, if the electromagnetic force Fm is to be made larger than the spring force Fs0 even in the range of the lift amounts D1 to D3, it is necessary to improve the performance of the electromagnet. When the electromagnet is designed so that Fm> Fs0 at all lift amounts D, the control response of the current flowing through the electromagnet becomes worse due to the increase in the size of the electromagnet or the increase in the number of turns of the electromagnet. Problem arises.

  On the other hand, the lower spring 86 used in the present embodiment has characteristics as indicated by the spring force Fs1. The lower spring 86 is a coil spring. When the coil spring receives a compressive force, the wire rod is twisted at each portion and contracts as a whole. If the wire rod is uniform from the neutral position to the lift amount D2, the lower-pitch spring 86 having an unequal pitch causes the wire rod to be twisted as a whole and contracts. However, if the portion of the narrow pitch P2 is contracted to some extent, the pitch becomes zero first and cannot be further contracted. Then, the part which can be shrunk | reduced according to the force which acts is only a part of wide pitch P1. Accordingly, when the lower spring 86 is viewed as a whole, if the applied force is increased when the lift amount is greater than D2, the change in displacement is reduced, and the elastic constant of the spring is increased.

  That is, the elastic constant of the lower spring 86 is such that the magnetic member is closer to the neutral position than the first position (lift amount D1) than when the disk 74 is in the first position (lift amount D3). It is smaller when there is. In other words, in the lower spring 86, the elastic constant from the neutral position to the lift amount D2 is smaller than the elastic constant in the region of the lift amount D2 or more.

  Therefore, the attractive force of the valve opening electromagnet can be made larger than the elastic force of the lower spring 86 from the neutral position to the valve opening position without specially increasing the performance of the electromagnet. Thus, since the spring force is reduced in the region of the lift amount where the electromagnetic force in the vicinity indicated by the arrow A1 is small, the electromagnetically driven valve of the present embodiment is caused to vibrate in order to give the valve an inertial force. It is possible to perform initial driving without requiring complicated control.

  As an example of an unequal pitch spring, FIG. 3 shows an example of a spring whose pitch is changed in two stages of P1 and P2, but the change in pitch is changed in three stages, four stages or even continuously. In this way, an unequal pitch spring that further conforms to the attraction characteristics of the electromagnet that is inversely proportional to the square of the distance may be used.

FIG. 5 is a diagram for explaining the initial drive control current of the electromagnetically driven valve according to the present embodiment.
Referring to FIG. 5, at time t0 to t1, coil current Ic is increased to an initial drive current that does not exceed the allowable current. Between times t1 and t2, the lift amount D gradually approaches the valve opening position from the neutral position. From time t2 to t3, the value of the coil current Ic is reduced from the initial drive current to the holding current so that the valve does not sit violently at the valve opening position.

  After time t3, a holding current for holding the valve open state where the valve is stationary at the valve opening position is applied to the valve opening electromagnet as the coil current Ic.

FIG. 6 is a view for explaining another example of the lower spring 86.
Referring to FIG. 6, the lower spring 86 b is a coil spring through which the valve shaft 88 passes through the center, and has one end in contact with the retainer 84 and the other end in contact with the cylinder head 10. Unlike the case of FIG. 4, the lower spring 86 b is a spring having an equal pitch.

  The retainer 84 is fixed to the valve shaft 88 with a valve cotter. When the disc 74 is attracted by the valve opening electromagnet and the valve shaft 88 is displaced from the neutral position toward the valve opening position, the lower spring 86 is compressed and generates an elastic force that pushes up the valve shaft.

  Here, the lower spring 86c is disposed inside the lower spring 86b. The length of the lower spring 86c is shorter than the length of the lower spring 86b. The lower spring 86c and the lower spring 86b constitute a multiple spring. Such a spring is also called a double spring or a double row spring.

  Such a multiple spring has a small elastic constant while the retainer 84 is not in contact with the lower spring 86c, and has a larger elastic constant when the lower spring 86b is compressed so that the retainer 84 is in contact with the lower spring 86c. Become.

  Even with such a multiple spring, the characteristics of the spring force Fs1 shown in FIG. 4 can be realized, so that an electromagnetically driven valve having a small physique can be controlled as easily as the unequal pitch spring shown in FIG. Can be realized.

FIG. 7 is a view for explaining another electromagnetically driven valve to which the present invention can be applied.
The electromagnetically driven valve shown in FIG. 7 includes a disk 174 that is a swingable magnetic member, a valve closing electromagnet including a coil 180 and an electromagnetic core 172, and a valve opening electromagnet including a coil 182 and an electromagnetic core 178. Including.

  A valve shaft is attached to the working end of the disk 174 opposite to the swing center side. Retainers 185 and 184 are provided above and below the attachment portion. An upper spring 189 is provided between the retainer 185 and the cylinder head, and a lower spring 188 is provided between the retainer 184 and the cylinder head.

  In the electromagnetically driven valve having such a configuration, an unequal pitch spring or multiple springs are applied to the lower spring 188 and the upper spring 189. By doing so, the characteristics of the spring can be matched with the attraction characteristics of the electromagnet not only on the valve opening side but also on the valve closing side.

  FIG. 8 is a view for explaining still another electromagnetically driven valve to which the present invention can be applied.

  The electromagnetically driven valve shown in FIG. 8 includes a disk 274 that is a swingable magnetic member, a valve closing electromagnet including a coil 280 and an electromagnetic core 272, and a valve opening electromagnet including a coil 282 and an electromagnetic core 278. Including.

  A valve shaft is attached to the center of the disk 174. The valve shaft passes through holes provided in the central portions of the electromagnetic cores 272 and 278. A retainer 285 is attached to a portion of the valve shaft that protrudes from the electromagnetic core 272, and a retainer 284 is attached to a portion of the valve shaft that protrudes from the electromagnetic core 278.

  An upper spring 289 is provided between the retainer 285 and the cylinder head, and a lower spring 288 is provided between the retainer 284 and the cylinder head.

  In the electromagnetically driven valve having such a configuration, an unequal pitch spring or multiple springs are applied to the lower spring 288 and the upper spring 289. By doing so, the characteristics of the spring can be matched with the attraction characteristics of the electromagnet not only on the valve opening side but also on the valve closing side.

  As described above, according to the present embodiment, the elastic constant of the spring is changed so as to conform to the characteristics of the electromagnetic force of the electromagnet with respect to the displacement of the disk 74. In addition, the size of the electromagnet can be small even during normal operation. In addition, power consumption can be reduced.

  Further, the present invention is not limited to the monocoil type or swing type electromagnetically driven valve, but can be applied to other types of electromagnetically driven valves. However, in the case of a monocoil type electromagnetically driven valve, the valve opening electromagnet and the valve closing electromagnet cannot be controlled independently, and the number of turns that determines the L component of the coil depends on the valve opening electromagnet and the valve closing valve. The effect is particularly expected in the case of a monocoil type electromagnetically driven valve because it is the sum of the coils of the electromagnet and because it is affected by the attractive force on the valve closing electromagnet side when the disc is attracted by the valve opening electromagnet. it can.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure which shows schematic structure of the electromagnetically driven valve which concerns on embodiment of this invention. It is the block diagram which showed the structure regarding the drive and control of an electromagnetically driven valve. It is the figure which showed an example of the lower spring 86 of FIG. It is the figure which showed the relationship between the elastic force of the lower spring 86, and the electromagnetic force of the electromagnet for valve opening. It is a figure for demonstrating the initial stage drive control current of the electromagnetically driven valve of this Embodiment. FIG. 10 is a diagram for explaining another example of the lower spring 86. It is a figure for demonstrating the other electromagnetically driven valve which can apply this invention. It is a figure for demonstrating the other electromagnetically driven valve which can apply this invention.

Explanation of symbols

  6 Crank angle sensor, 10 Cylinder head, 11 DC power supply, 31 Memory, 62 Housing, 68 Torsion bar, 72, 78, 172, 178, 272, 278 Electromagnetic core, 74, 174, 274 Disc, 76 Intermediate stem, 80, 82, 180, 182, 280, 282 Coil, 84, 184, 185, 284, 285 Retainer, 86, 86b, 86c, 188, 288 Lower spring, 87 Valve, 88 Valve shaft, 89 Stroke ball bearing, 189, 289 Upper spring.

Claims (7)

A valve having a valve shaft and reciprocating along a direction in which the valve shaft extends;
A magnetic member that moves in conjunction with the valve;
A first electromagnet that attracts the magnetic member and holds it in a predetermined position of either one of valve opening and valve closing;
A first elastic member that applies a force to the magnetic member to separate the magnetic member from the first electromagnet from the predetermined position toward the neutral position;
The elastic constant of the first elastic member is smaller when the magnetic member is in the second position closer to the neutral position than the first position than when the magnetic member is in the first position. , Electromagnetically driven valve.   The electromagnetically driven valve according to claim 1, wherein the first elastic member is a coil spring having an unequal pitch.   2. The electromagnetically driven valve according to claim 1, wherein the first elastic member is a multiple spring in which a first coil spring and a second coil spring are combined.   In order to move the magnetic member in a direction from the neutral position toward the predetermined position, an attractive current that flows through the first electromagnet so that an attractive force of the first electromagnet is larger than an elastic force of the elastic member. The electromagnetically driven valve according to any one of claims 1 to 3, further comprising a control device that controls the motor. The predetermined position is a valve opening position,
A second electromagnet that attracts the magnetic member and holds it in a closed position;
And a second elastic member that applies a force to the magnetic member to separate the magnetic member from the second electromagnet toward the neutral position by applying an elastic force to the valve shaft. The electromagnetically driven valve described in 1. The first electromagnet is:
Including a first coil;
The second electromagnet is:
Including a second coil connected to the first coil;
The electromagnetically driven valve according to claim 5, wherein an equal current flows through the first and second coils.   Control for reducing the current flowing through the first and second coils from a suction current having a predetermined current value required for suction to the predetermined position to a holding current necessary for holding the current at the predetermined position. The electromagnetically driven valve according to claim 6, further comprising a device.

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