JP2004304921A - Electromagnetic actuator-controlling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic actuator-controlling device that can prevent a magnetic circuit of an electromagnetic actuator from being magnetized, and that can prevent the sticking of a moving core that is caused to occur by a ferromagnetic foreign material attracted to a magnetized magnetic circuit. <P>SOLUTION: An ECU 4 performs self-demagnetization of gradually reducing a current value given to a coil 17, while giving currents of different polarity to the coil 17 alternately, when an ignition switch is in an OFF state. Then, magnetic force generated in the magnetic circuit gradually decreases and fades out while alternating the magnetic poles. Because this self-demagnetization prevents the magnetization of the magnetic circuit of the electromagnetic actuator 13, sticking of the moving core 15 can be prevented that is caused to occur by the ferromagnetic foreign material attracted to the magnetized magnetic circuit. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for an electromagnetic actuator.
[0002]
[Prior art]
2. Description of the Related Art There is known a device that varies the valve timing of an engine by continuously varying the position of a spool (valve element) of an oil flow control valve by controlling the operation of an electromagnetic actuator.
The electromagnetic actuator used in the variable valve timing device continuously changes the position of the spool in accordance with the amount of current supplied to the coil, and the amount of current supplied to the coil is controlled by a controller (for example, see Patent Reference 1).
[0003]
[Patent Document 1]
JP-A-10-280919
[Problems to be solved by the invention]
Although not particularly described in Patent Literature 1, usually, the amount of current supplied to the coil is continuously varied by duty ratio control, so that the direction of current supplied to the coil is always constant.
When a current in a certain direction always flows through the coil, the magnetic circuit (ferromagnetic material) is gradually magnetized in the electromagnetic actuator.
[0005]
When the magnetic circuit is magnetized, ferromagnetic foreign substances (wear powder, cutting powder, and the like) are attracted to the magnetized magnetic circuit, and thus there is a possibility that the ferromagnetic foreign substance will not adhere to the magnetized magnetic circuit or will be laminated. . If foreign matter does not adhere to the moving core or members around the moving core, or the like, the moving core may be fixed.
[0006]
[Object of the invention]
The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent a magnetic circuit of an electromagnetic actuator from being magnetized, so that a ferromagnetic foreign substance is attracted to a magnetized magnetic circuit. An object of the present invention is to provide an electromagnetic actuator control device that can prevent the moving core from sticking.
[0007]
[Means for Solving the Problems]
[Means of claim 1]
The control device for an electromagnetic actuator according to claim 1 gradually increases the current value to be applied to the coil while alternately applying currents having different polarities to the coil when the electromagnetic actuator is started or stopped, or while the electromagnetic actuator is stopped. Self-demagnetization for reducing the size is performed.
As a result, since the magnetization of the magnetic circuit of the electromagnetic actuator is prevented, it is possible to prevent the moving core from sticking due to the attraction of the ferromagnetic foreign matter to the magnetized magnetic circuit.
[0008]
It is preferable that the self-demagnetization be performed when the electromagnetic actuator is stopped. By performing the self-demagnetization when the electromagnetic actuator is stopped, the influence of hydraulic pulsation due to the demagnetizing current can be avoided.
[0009]
[Means of Claim 2]
A control device for an electromagnetic actuator employing the means of claim 2 is used for controlling an electromagnetic control valve that displaces the position of a valve body (movable element) of a valve by the electromagnetic actuator.
As described above, by using the present invention to control the electromagnetic control valve, the reliability of the electromagnetic control valve can be improved.
[0010]
[Means of Claim 3]
A control device for an electromagnetic actuator adopting the means of claim 3 is combined with a variable valve timing mechanism to control the hydraulic pressure generated by the hydraulic pressure source during operation of the internal combustion engine relative to the advance chamber and the retard chamber. It is used for controlling an oil flow control valve for supplying and discharging.
[0011]
As described above, by using the present invention to control the oil flow control valve that controls the hydraulic pressure of the variable valve timing mechanism, the reliability of the oil flow control valve can be improved.
Therefore, the reliability of the variable valve timing device (VVT) including the variable valve timing mechanism (VCT) and the hydraulic circuit using the oil flow control valve can be improved.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described using examples and modifications.
〔Example〕
An embodiment will be described with reference to FIGS.
First, the variable valve timing device will be described with reference to FIG.
[0013]
The variable valve timing device shown in this embodiment is attached to a camshaft (any one of an intake valve, an exhaust valve, and an intake / exhaust camshaft) of an internal combustion engine (hereinafter referred to as an engine). Can be continuously varied.
The variable valve timing device (VVT) includes a variable valve timing mechanism 1 (VCT), a hydraulic circuit 3 having an oil flow control valve 2, and an ECU 4 for controlling the oil flow control valve 2 (abbreviation of engine control unit: control). (Equivalent to a device).
[0014]
(Explanation of the variable valve timing mechanism 1)
The variable valve timing mechanism 1 is provided so as to be rotatable relative to the shoe housing 5 (corresponding to a rotary driver) that is driven to rotate in synchronization with the crankshaft of the engine, and is integrated with the camshaft. A vane rotor 6 (corresponding to a rotation follower) that rotates relative to the shoe housing 5 by a hydraulic actuator configured in the shoe housing 5 to rotate the vane rotor 6 relative to the shoe housing 5. Is changed to the advance side or the retard side.
[0015]
The shoe housing 5 is coupled to a sprocket that is driven to rotate by a crankshaft of the engine via a timing belt, a timing chain, or the like, by a bolt or the like, and rotates integrally with the sprocket. As shown in FIG. 4, a plurality of (three in this embodiment) substantially fan-shaped recesses 7 are formed inside the shoe housing 5. Note that the shoe housing 5 rotates clockwise in FIG. 4, and this rotation direction is the advance direction.
On the other hand, the vane rotor 6 is positioned at the end of the camshaft by a positioning pin or the like, and is fixed to the end of the camshaft by a bolt or the like, and rotates integrally with the camshaft.
[0016]
The vane rotor 6 includes a vane 6a that partitions the inside of the recess 7 of the shoe housing 5 into an advance chamber 7a and a retard chamber 7b. The vane rotor 6 is provided rotatably within a predetermined angle with respect to the shoe housing 5. Have been.
The advancing chamber 7a is a hydraulic chamber for driving the vane 6a to the advancing side by hydraulic pressure, and is formed in the concave portion 7 on the anti-rotation direction side of the vane 6a. Is a hydraulic chamber for driving the vane 6a to the retard side by hydraulic pressure. The liquid tightness in each of the chambers 7a and 7b is maintained by the seal member 8 and the like.
[0017]
(Description of hydraulic circuit 3)
The hydraulic circuit 3 supplies and discharges oil to the advance chamber 7a and the retard chamber 7b, and generates a hydraulic pressure difference between the advance chamber 7a and the retard chamber 7b to rotate the vane rotor 6 relative to the shoe housing 5. An oil pump 9 driven by a crankshaft or the like, and an oil flow control valve 2 for switchingly supplying oil pumped by the oil pump 9 to the advance chamber 7a or the retard chamber 7b. .
[0018]
The oil flow control valve 2 will be described with reference to FIG.
The oil flow control valve 2 includes a spool valve 10 including a sleeve 11 and a spool 12, and an electromagnetic actuator 13 that drives the spool 12 in the axial direction.
The sleeve 11 has a substantially cylindrical shape, and has a plurality of input / output ports. Specifically, the sleeve 11 of the present embodiment communicates with the insertion hole 11a that supports the spool 12 slidably in the axial direction, the hydraulic supply port 11b that communicates with the oil discharge port of the oil pump 9, and the advance chamber 7a. An advance chamber communication port 11c, a retard chamber communication port 11d communicating with the retard chamber 7b, and a drain port 11e for returning oil into the oil pan 9a are formed.
[0019]
The hydraulic pressure supply port 11b, the advance chamber communication port 11c, and the retard chamber communication port 11d are holes formed on the side surface of the sleeve 11, and extend from the left side (opposite the coil side) to the right side (coil side) in FIG. , A drain port 11e, an advance chamber communication port 11c, a hydraulic pressure supply port 11b, a retard chamber communication port 11d, and a drain port 11e.
[0020]
The spool 12 includes four large-diameter portions 12a (lands) for blocking ports having outer diameters substantially matching the inner diameter of the sleeve 11 (diameter of the insertion hole 11a).
Between the large-diameter portions 12a, a small-diameter portion 12b for advancing chamber drain and a small-diameter portion 12c for hydraulic pressure supply, which change the communication state of a plurality of input / output ports (11b to 11e) according to the axial position of the spool 12. , A small diameter portion 12d for the retard chamber drain is formed.
The advance chamber drain small diameter portion 12b is for draining the hydraulic pressure of the advance chamber 7a when the hydraulic pressure is supplied to the retard chamber 7b, and the hydraulic supply small diameter portion 12c is provided for the advance chamber 7a or the retard chamber. The hydraulic pressure is supplied to one of the angular chambers 7b, and the small diameter portion 12d for draining the retard chamber is for draining the hydraulic pressure of the retard chamber 7b when the hydraulic pressure is supplied to the advance chamber 7a. is there.
[0021]
The spool 12 is integrally provided with a small-diameter shaft 12e extending inside a coil 17 described later. The shaft 12e is connected to a moving core 15 described later by press fitting or the like.
On the other hand, a spring 14 (biasing means) for biasing the spool 12 toward the coil (right side in FIG. 1) is disposed on the opposite side of the spool 12 from the coil (left side in FIG. 1).
[0022]
The electromagnetic actuator 13 includes a moving core 15, a stator 16, a coil 17, a yoke 18, and a connector 19.
The moving core 15 is formed of a magnetic metal (for example, iron: a ferromagnetic material forming a magnetic circuit) that is magnetically attracted to the stator 16, and is fixed to the end of the shaft 12e by press fitting or the like. It is something. Therefore, the moving core 15 moves in the axial direction integrally with the spool 12.
[0023]
The stator 16 is a magnetic metal (for example, a disc-shaped portion 16a sandwiched between the sleeve 11 and the coil 17) and a cylindrical portion 16b that guides the magnetic flux of the disc 16a to the vicinity of the moving core 15. , Iron: a ferromagnetic material constituting a magnetic circuit), and a main gap MG (magnetic attraction gap) is formed between the moving core 15 and the cylindrical portion 16b.
At the end of the cylindrical portion 16b, a concave portion 16c is formed, into which the end of the moving core 15 is inserted without contact, and when the moving core 15 enters into the concave portion 16c, the moving core 15 is fixed to the stator 16b. The moving core 15 and a part of the stator 16 are provided so as to intersect in the axial direction when sucked into the end of the moving core 15. The end of the cylindrical portion 16b is formed with a taper 16d so that the magnetic attraction does not change with respect to the stroke of the moving core 15.
[0024]
The coil 17 is a magnetic force generating means for generating a magnetic force when energized and causing the moving core 15 to be magnetically attracted to the stator 16, and is formed by winding a number of enamel wires around a resin bobbin 17 a.
The yoke 18 is a magnetic metal (for example, iron: a ferromagnetic material forming a magnetic circuit) including an inner cylindrical portion 18a covering the periphery of the moving core 15 and an outer cylindrical portion 18b covering the periphery of the coil 17. The claw portion 18c formed on the left side is connected to the sleeve 11 by caulking. The inner cylinder portion 18a transfers the magnetic flux to and from the moving core 15, and a side gap SG (magnetic flux transfer gap) is formed between the moving core 15 and the inner cylinder portion 18a.
The connector 19 is a connection means for making an electrical connection to the ECU 4 via a connection line, and has terminals 19 a connected to both ends of the coil 17 therein.
[0025]
When the coil 17 is turned off, the spool 12 and the moving core 15 are displaced toward the coil (the right side in FIG. 1) by the biasing force of the spring 14 and stop when the coil 17 is turned off.
In this stopped state, the maximum gap of the main gap MG is determined, and the positioning of the spool 12 with respect to the sleeve 11 is performed. In the oil flow control valve 2 of the present embodiment, the spool 12 and the moving core 15 are displaced toward the coil side by the contact between the ring-shaped collar 20 mounted inside the stator 16 and the step 12f formed on the spool 12. A stopper is formed when the operation is performed (when the coil 17 is turned off).
Reference numeral 21 shown in FIG. 1 is an O-ring for sealing, and reference numeral 22 is a cup for preventing oil leakage.
[0026]
(Description of ECU 4)
The ECU 4 linearly controls the axial position of the spool 12 by controlling the amount of current supplied to the coil 17 of the electromagnetic actuator 13, and reduces the operating oil pressure according to the operating state of the engine to the advance chamber 7 a and the retarding chamber 7. It is generated in the angular chamber 7b to control the advance phase of the camshaft. The details of the ECU 4 will be described later.
[0027]
(Explanation of the operation of the variable valve timing device)
When the ECU 4 advances the camshaft according to the driving state of the vehicle, the ECU 4 increases the amount of current supplied to the coil 17. Then, the magnetic force generated by the coil 17 increases, and the moving core 15 and the spool 12 move to the opposite side of the coil (the left side in FIG. 1: the advance side). Then, the communication ratio between the hydraulic pressure supply port 11b and the advance chamber communication port 11c increases, and the communication ratio between the retard chamber communication port 11d and the drain port 11e increases. As a result, the oil pressure in the advance chamber 7a increases, and conversely, the oil pressure in the retard chamber 7b decreases, and the vane rotor 6 is displaced relatively to the shoe housing 5 to advance the camshaft. I do.
[0028]
Conversely, when the ECU 4 retards the camshaft according to the driving state of the vehicle, the ECU 4 decreases the amount of current supplied to the coil 17. Then, the magnetic force generated by the coil 17 decreases, and the moving core 15 and the spool 12 move to the coil side (the right side in FIG. 1: the retard side). Then, the communication ratio between the hydraulic pressure supply port 11b and the retard chamber communication port 11d increases, and the communication ratio between the advance chamber communication port 11c and the drain port 11e increases. As a result, the oil pressure in the retard chamber 7b increases, and conversely, the oil pressure in the advance chamber 7a decreases, the vane rotor 6 is displaced toward the retard side relative to the shoe housing 5, and the camshaft is retarded. I do.
[0029]
[Features of the embodiment according to the present invention]
The ECU 4 controls the amount of current supplied to the coil 17 of the electromagnetic actuator 13 (hereinafter, supplied current amount) by duty ratio control, and includes a computer control unit, a driver (EDU), and the like. Note that the duty ratio control is to variably control the supply current amount by changing the ratio of the ON time and the OFF time per cycle at the control frequency (PWM frequency).
[0030]
The computer control unit includes a CPU, a storage device (RAM, ROM, and the like), an I / O port (DAC, ADC), and the like, and includes a crank angle, an engine rotation speed, and an accelerator detected by various sensors (not shown). The supply current amount is obtained by calculation in accordance with the operation state of the engine such as the opening degree, and the duty ratio (the ratio of the ON time to the OFF time per cycle) is determined in accordance with the obtained supply current amount.
The driver performs ON / OFF control of the coil 17 of the electromagnetic actuator 13 based on a duty ratio control signal (command signal) output from the computer control unit.
[0031]
The amount of current supplied to the coil 17 is continuously varied by duty ratio control. During the control of the electromagnetic actuator 13, the flow direction of the current supplied to the coil 17 is always constant.
When a current always flows in a fixed direction in the coil 17 as described above, a magnetic circuit (ferromagnetic material: moving core 15, stator 16, yoke 18, etc.) provided with a magnetic force by the coil 17 as described in the related art section. Are gradually magnetized.
When the magnetic circuit is magnetized in this way, the ferromagnetic foreign matter (wear powder, cutting powder, etc.) is attracted to the magnetized magnetic circuit, so that there is a possibility that the ferromagnetic foreign matter may not adhere to the magnetic circuit or may be laminated. This causes the moving core 15 to adhere.
[0032]
Therefore, when the electromagnetic actuator 13 is stopped (when the variable valve timing device is stopped, specifically, when the ignition switch is turned off), the ECU 4 of this embodiment supplies currents having different polarities as shown in FIG. Self-demagnetization is performed in which the current value applied to the coil 17 is gradually reduced while being alternately applied to the coil 17. That is, a gradually decreasing alternating current is applied to the coil 17.
[0033]
Then, as shown in FIG. 3, the magnetic force generated in the magnetic circuit gradually decreases and disappears while alternating the magnetic poles. The horizontal axis H in FIG. 3 indicates the strength of the magnetic field, and the vertical axis B indicates the strength of the magnetization.
This self-demagnetization prevents the magnetization of the magnetic circuit of the electromagnetic actuator 13. Therefore, it is possible to prevent the moving core 15 from sticking due to the attraction of the ferromagnetic foreign matter to the magnetized magnetic circuit.
As described above, since the moving core 15 is prevented from being fixed due to the magnetization of the magnetic circuit, the reliability of the oil flow control valve 2 is improved, and the reliability of the variable valve timing device (VVT) can be improved.
[0034]
(Modification)
In the above-described embodiment, an example in which the self-demagnetization is performed when the electromagnetic actuator 13 is stopped has been described. (For example, when a predetermined time has elapsed after the stop), self-demagnetization may be performed.
[0035]
The variable valve timing mechanism 1 shown in the above embodiment is an example for explaining the embodiment, and any other structure may be used as long as the advance angle can be adjusted by a hydraulic actuator inside the variable valve timing mechanism 1. good.
For example, in the above-described embodiment, an example in which three concave portions 7 are formed in the shoe housing 5 and three vanes 6a are provided on the outer peripheral portion of the vane rotor 6 has been described, but the number of concave portions 7 and the number of vanes 6a are The number of the concave portions 7 and the number of the vanes 6a may be other numbers as long as the number is one or more in terms of the configuration.
Also, an example has been shown in which the shoe housing 5 rotates synchronously with the crankshaft and the vane rotor 6 rotates integrally with the camshaft, but the vane rotor 6 is rotated synchronously with the crankshaft so that the shoe housing 5 rotates integrally with the camshaft. You may comprise.
[0036]
In the above-described embodiment, an example in which the spool 12 having the large-diameter portion 12a and the small-diameter portions 12b to 12d is used has been described. However, the structure of the spool 12 is not limited. May be.
In the above embodiment, an example is shown in which a hole is formed in the side surface of the sleeve 11 to provide input / output ports (in the embodiment, a hydraulic supply port 11b, an advance chamber communication port 11c, a retard chamber communication port 11d, and the like). However, the structure of the sleeve 11 is not limited. For example, a plurality of input / output ports may be formed by forming a through hole in the diameter direction of the sleeve 11.
[0037]
The structure of the electromagnetic actuator 13 shown in the above embodiment is an example for describing the embodiment, and another structure may be used. For example, the moving core 15 may be arranged outside the coil 17 in the axial direction.
In the above-described embodiment, the example in which the spool 12 is displaced to the opposite side of the coil when the coil 17 is turned on is described. However, the spool 12 may be displaced to the side of the coil when the coil 17 is turned on.
[0038]
In the above embodiment, the present invention is applied to the control of the oil flow control valve 2 combined with the variable valve timing mechanism 1. However, the present invention is also applied to the control of all the oil flow control valves 2 that switch the oil flow and the oil flow direction. Applicable.
Further, the present invention is not limited to the control of the oil flow control valve 2, but can be applied to the control of an electromagnetic actuator 13 that drives a valve body of the valve.
Further, the present invention is not limited to the control of the electromagnetic actuator 13 that drives the valve element, but can be applied to the control of the electromagnetic actuator 13 that drives a mover other than the valve element.
[Brief description of the drawings]
FIG. 1 is a sectional view along an axial direction of an oil flow control valve.
FIG. 2 is a graph showing a change in an alternating current applied to a coil.
FIG. 3 is a graph showing a change in magnetic force of a magnetic circuit.
FIG. 4 is a schematic view of a variable valve timing device.
[Explanation of symbols]
1 variable valve timing mechanism 2 oil flow control valve 3 hydraulic circuit 4 ECU (control device)
5 Shoe housing (rotary drive)
6 Vane rotor (rotary follower)
7a advance chamber 7b retard chamber 12 spool (valve element)
13 Electromagnetic actuator 15 Moving core (component of magnetic circuit)
16 Stator (component of magnetic circuit)
17 coil 18 yoke (component of magnetic circuit)

Claims (3)

A coil that generates a magnetic force when energized, an electromagnetic actuator including a moving core that is magnetically attracted to the coil,
A control device that controls a displacement amount of the moving core by controlling a supply current amount to the coil,
This control device self-demagnetizes when the electromagnetic actuator is started or stopped, or while the electromagnetic actuator is stopped, while alternately applying currents having different polarities to the coil, and gradually reducing the current value applied to the coil. A control device for an electromagnetic actuator. The control device for an electromagnetic actuator according to claim 1,
The electromagnetic actuator control device, wherein the electromagnetic actuator displaces a position of a valve body in a valve according to a supplied current amount. The control device for an electromagnetic actuator according to claim 2,
The valve is
A rotary drive body that is driven to rotate in synchronization with the crankshaft of the internal combustion engine,
A rotation follower that is provided so as to be relatively rotatable with respect to the rotary driving body and rotates integrally with a camshaft of the internal combustion engine;
By supplying hydraulic pressure to an advance chamber formed between the rotary driving body and the rotation driven body, the camshaft is displaced to the advance side together with the rotation driven body with respect to the rotation driving body, Valve timing for displacing the camshaft to the retard side with the rotary driven body with respect to the rotary drive by supplying hydraulic pressure to a retard chamber formed between the rotary driven body and the rotary driven body. Combined with the variable mechanism,
A control device for an electromagnetic actuator, characterized in that the control device is an oil flow control valve that supplies and discharges a hydraulic pressure generated by a hydraulic pressure source to the advance chamber and the retard chamber during operation of the internal combustion engine.

Images