JP2004301233A - Manufacturing method for electric spool valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve problems wherein the number of parts increases when a yoke and a sleeve are separate parts and burr caused during manufacture is viscous because a soft iron material is used when the yoke and the sleeve are integrally provided, thereby making it difficult to remove burr. <P>SOLUTION: First, the sleeve 11 and the yoke 18 are integrally formed by the soft iron material, and then surface hardening treatment is applied. In this hardening treatment process, viscous burr is hardened and becomes fragile. In the following deburring process, it is enough to remove non-viscous fragile burr, which can be easily removed. The sleeve 11 and the yoke 18 are constituted by one integral part to reduce the number of parts, and burr which becomes a problem when integrating them can be easily removed. Since a surface of the sleeve 11 is hardened, durability of an oil flow control valve 2 can be increased. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing an electric spool valve in which a spool of a spool valve is operated by an electromagnetic actuator.
[0002]
[Prior art]
The structure of a conventional electric spool valve will be described with reference to FIG. The electric spool valve shown in FIG. 4 is an oil flow control valve used in a variable valve timing device.
The oil flow control valve J1 includes a sleeve J6 formed with input / output ports (in this figure, a hydraulic pressure supply port J2, an advance chamber communication port J3, a retard chamber communication port J4, and a drain port J5), and a sleeve J6. The spool J7 is configured to switch between the input / output ports J2 to J5 by being displaced in the axial direction inside the spool, and an electromagnetic actuator J8 for driving the spool J7 in the axial direction.
[0003]
The spool J7 and the moving core J11 are in contact with each other via a shaft J15. By adjusting the amount of current (conduction ratio) applied to the coil J12, the axial displacement of the spool J7 together with the moving core J11 is reduced. Adjusted. With this operation, the ratio of the hydraulic pressure applied to the advance chamber and the retard chamber is linearly varied, and the advance amount of the camshaft is linearly varied (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-10-280919
[Problems to be solved by the invention]
The oil flow control valve J1 disclosed in Patent Document 1 described above has a problem in that the number of components increases because the yoke J13 and the sleeve J6 that cover the periphery of the coil J12 are formed as separate components.
Therefore, as shown in FIG. 5, it is conceivable to provide the sleeve J6 and the yoke J13 integrally to reduce the number of parts. When the sleeve J6 and the yoke J13 are provided integrally, a soft iron material is used with priority given to the magnetic properties of the yoke J13.
[0006]
In a manufacturing process, if a hole is formed in a component made of a soft iron material, a burr B is generated by cutting. As a specific example, as shown in FIG. 5, when the through hole J14 for disposing the spool J7 is formed by a drill or the like, burrs B occur at intersections with other holes (such as input / output ports). For this reason, an operation for removing burrs B generated during the manufacturing process is required.
However, since the soft iron material is sticky, it is difficult to remove the burrs B generated on the parts.
[0007]
[Object of the invention]
The present invention has been made in view of the above circumstances, and has as its object to reduce the number of parts by forming the yoke and the sleeve as one integral part, and to easily remove burrs that are a problem at that time. Another object of the present invention is to provide a method of manufacturing an electric spool valve which can be removed.
[0008]
[Means for Solving the Problems]
[Means of claim 1]
In the method for manufacturing an electric spool valve according to the first aspect, a surface hardening treatment is performed after the sleeve and the yoke are integrally formed of a soft iron material. As a result, burrs generated in the forming step are also surface hardened. That is, the burrs that have been sticky before the curing treatment are also hardened by the surface curing treatment. Since the hardened burr is not sticky and brittle, the burr can be easily removed in the deburring step.
In addition, since the surface of the sleeve is hardened, wear due to sliding of the spool can be suppressed, and the durability of the spool valve is improved.
As described above, by adopting the method of manufacturing the electric spool valve according to the first aspect, the yoke and the sleeve can be configured as one integrated part, so that the number of parts can be reduced. Can be easily removed. Further, the wear resistance of the spool can be improved, and the durability of the spool valve can be improved.
[0009]
[Means of Claim 2]
According to a second aspect of the present invention, there is provided a method of manufacturing an electric spool valve in which the thickness of a hardened surface layer applied in a hardening process is suppressed to 0.1 mm or less.
As described above, since the thickness of the hardened surface layer is extremely thin, the effect of the hardened surface layer interposed in the magnetic transfer portion between the yoke and another member (for example, a stator or the like) can be substantially eliminated. In other words, it is possible to suppress deterioration of magnetic properties due to the surface hardened layer applied to the yoke.
[0010]
[Means of Claim 3]
A method of manufacturing an electric spool valve adopting the means of claim 3 is combined with a hydraulic actuator of a variable valve timing mechanism, and transfers a hydraulic pressure generated by a hydraulic pressure source during operation of an internal combustion engine to an advance chamber and a retard chamber. This is applied to an oil flow control valve that supplies and discharges relatively.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described using examples and modifications.
〔Example〕
First, the variable valve timing device will be described with reference to FIG.
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 (abbreviation of engine control unit) for controlling the oil flow control valve 2. It is composed of
[0012]
(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.
[0013]
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. 3, 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. 3, 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.
[0014]
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.
[0015]
(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. .
[0016]
The oil flow control valve 2 will be described with reference to FIG.
The oil flow control valve 2 corresponds to an electric spool valve, and includes a spool valve 10 including a sleeve 11 and a spool 12, and an electromagnetic actuator 13 that drives the spool 11 in an axial direction.
The sleeve 11 has a substantially cylindrical shape, and is provided integrally with the yoke 18 by iron (specifically, soft iron) having excellent magnetic properties as described later. The sleeve 11 has a plurality of input / output ports. Specifically, the sleeve 11 of the present embodiment includes a through hole 11a having no step in the axial direction for supporting the spool 12 slidably in the axial direction, a hydraulic supply port 11b communicating with the oil discharge port of the oil pump 9, An advance chamber communication port 11c communicating with the angular chamber 7a, 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.
[0017]
The hydraulic pressure supply port 11b, the advance chamber communication port 11c, and the retard chamber communication port 11d are holes that penetrate in the diameter direction of the sleeve 11, and extend from the left side (opposite the coil side) to the right side (coil side) of FIG. , A retard chamber communication port 11d, a hydraulic pressure supply port 11b, and an advance chamber communication port 11c.
Further, the drain port 11e is formed at the left end (opposite the coil side) of the sleeve 11 in FIG.
[0018]
The spool 12 is a pipe member (for example, a processed cylindrical pipe) having an outer diameter substantially matching the inner diameter (diameter of the through hole 11 a) of the sleeve 11, and is axially inside the through hole 11 a of the sleeve 11. It is slidably supported.
A hydraulic pressure switching groove 12a is formed around the entire periphery of the spool 12 substantially at the center. The hydraulic pressure switching groove 12a always communicates with the hydraulic pressure supply port 11b, and communicates with the retard chamber communication port 11d to supply hydraulic pressure to the retard chamber 7b as shown in FIG. In contrast, when the hydraulic pressure is supplied to the advance chamber 7a by communicating with the advance chamber communication port 11c, it is provided to be shut off from the retard chamber communication port 11d.
[0019]
Drain holes 12b are formed on both sides in the axial direction of the hydraulic pressure switching groove 12a, the inner and outer peripheries communicating with each other. The drain hole 12b communicates with the advance chamber communication port 11c when the communication between the hydraulic pressure supply port 11b and the advance chamber communication port 11c is interrupted as shown in FIG. Conversely, when the communication between the hydraulic pressure supply port 11b and the retard chamber communication port 11d is interrupted, the pressure is communicated with the retard chamber communication port 11d, and the hydraulic pressure in the retard chamber 7b is reduced. It is.
[0020]
The electromagnetic actuator 13 includes a moving core 14, a spring 15 (biasing means), a stator 16, a coil 17, a yoke 18, and a connector 19.
The moving core 14 is provided by a magnetic metal (for example, iron) that is magnetically attracted to the stator 16, and is press-fitted and fixed to the coil side (the right side in FIG. 1) of the spool 12. For this reason, the moving core 14 can move in the axial direction integrally with the spool 12.
The spring 15 is a compression coil spring disposed between the moving core 14 and the coil 17 and is a member that urges the spool 12 together with the moving core 14 toward the opposite side of the coil (left side in FIG. 1).
[0021]
The stator 16 is a magnetic metal (for example, iron) having a T-shaped cross section including a rod portion 16a disposed inside the coil 17 and a disk portion 16b on the right side of the rod portion 16a in FIG. ), A main gap MG (magnetic attraction gap) is formed between the moving core 14 and the rod-shaped portion 16a.
The coil 17 is a magnetic force generating means for generating a magnetic force when energized and magnetically attracting the moving core 14 to the stator 16, and is formed by winding a number of enamel wires around a resin bobbin 17a.
[0022]
The yoke 18 has a substantially cylindrical shape that covers the coil 17 and the moving core 14, and is provided integrally with the sleeve 11. A manufacturing method for integrally forming the sleeve 11 and the yoke 18 will be described later.
The yoke 18 is magnetically coupled to the disk portion 16b of the stator 16 on the right side of FIG. 1, and slidably covers the periphery of the moving core 14 in the axial direction on the left side of FIG. It is provided to deliver magnetism. That is, the side gap SG (magnetic flux transfer gap) is formed between the outer periphery of the moving core 14 and the yoke 18 covering the periphery.
The connector 19 is connection means for making an electrical connection to the ECU 4 via a connection line, and has terminals 19a connected to both ends of the coil 17 disposed therein.
[0023]
When the coil 17 is turned off, the spool 12 and the moving core 14 are displaced toward the opposite side of the coil (the left side in FIG. 1) by the urging force of the spring 15, and stop.
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 this embodiment, a ring-shaped collar 20 is arranged on the coil side (the right side in FIG. 1) of the sleeve 11, and the collar 20 and the opposite side of the moving core 14 on the coil side (the left side in FIG. 1). When the spool 12 and the moving core 14 are displaced toward the opposite side of the coil (when the coil 17 is turned off), the stopper is configured by the contact with the end surface.
Reference numeral 21 in FIG. 1 denotes an O-ring for sealing, which prevents oil in the oil flow control valve 2 from leaking to the outside.
[0024]
(Description of ECU 4)
The ECU 4 controls the amount of current (the energization ratio) supplied to the coil 17 of the electromagnetic actuator 13 in accordance with the operating state of the engine such as the crank angle, the engine rotation speed, and the accelerator opening detected by various sensors. The ECU 4 controls the axial position of the spool 12 to generate operating oil pressure in the advance chamber 7a and the retard chamber 7b according to the operating state of the engine. The ECU 4 supplies the hydraulic pressure to the coil 17 by PWM control or the like. The amount of current is controlled continuously.
[0025]
(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 14 and the spool 12 move to the coil side (the right 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 hole 12b 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.
[0026]
Conversely, when the ECU 4 retards the camshaft in accordance with the driving state of the vehicle, the ECU 4 reduces the amount of current supplied to the coil 17. Then, the magnetic force generated by the coil 17 decreases, and the moving core 14 and the spool 12 move to the opposite side of the coil (left side in FIG. 1: 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 hole 12b 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.
[0027]
[Features of the embodiment according to the present invention]
As described in the section of the prior art, as shown in FIG. 4, the conventional oil flow control valve J1 has a large number of parts because the sleeve J6 and the yoke J13 are formed as separate parts. Therefore, it is conceivable to provide the sleeve J6 and the yoke J13 integrally to reduce the number of parts.
In this case, the yoke J13 is manufactured using a soft iron material with priority given to the magnetic characteristics. However, when a hole or the like is formed, burrs B are generated by cutting as shown in FIG. For this reason, an operation for removing the burr B during the manufacturing process is required.
However, since the soft iron material is sticky, the burr B cannot be easily removed, and it has been difficult to remove the burr B.
[0028]
Therefore, in the present embodiment, the following manufacturing method is adopted in order to solve the above-mentioned problem.
(1) The sleeve 11 and the yoke 18 are integrally formed of a soft iron material (forming step).
(2) A hardening process is performed on the surfaces of the integrated sleeve 11 and yoke 18 formed in the forming process (hardening process).
(3) After the hardening process, the burrs B (reference numerals shown in FIG. 2) formed on the surfaces of the integrated sleeve 11 and yoke 18 are removed (burr removing process).
[0029]
The forming process is a process in which the sleeve 11 and the yoke 18 are provided with an integrated base component by a metal working technique such as forging, and the sleeve 11 and the yoke 18 are integrally formed by performing a working technique such as cutting.
In this forming step, as shown in FIG. 2, the through holes 11a are formed by using a boring apparatus such as a drill. When the through hole 11a is formed, burrs B occur at intersections between the through hole 11a and other holes.
[0030]
In the hardening process, a hardened layer is formed on the surface of the component (the sleeve 11 and the yoke 18 integrally formed) manufactured in the forming process by performing a surface hardening process such as a carburizing process, a nitriding process, and a boring process. It is a process.
Through this curing process, the burrs B generated in the forming process are also surface-hardened. That is, the burrs B that were sticky before the surface hardening treatment are also hardened by the surface hardening treatment, become less sticky and become brittle.
[0031]
In addition, it is desirable that the thickness of the surface hardened layer applied in the hardening process is suppressed to 0.1 mm or less. The reason is that the hardened surface layer impairs magnetic properties. Therefore, by suppressing the thickness of the surface hardened layer to 0.1 mm or less, the surface hardened portion interposed between the magnetic transfer portion between the yoke 18 and the stator 16 and the magnetic transfer portion (side gap SG) between the yoke 18 and the moving core 14. The influence of the layer can be almost eliminated, and the deterioration of the magnetic properties due to the surface hardened layer applied to the yoke 18 can be suppressed.
[0032]
The deburring step is a step of removing the burr B hardened in the hardening processing step. As described above, since the burr B is not sticky and brittle due to the curing process, the burr B can be easily removed.
For example, by performing high-pressure cleaning (a technique of spraying high-pressure water onto a component to wash the component) also as a deburring step, the burr B can be removed with high-pressure water at the same time as the cleaning. Instead of performing the deburring by high-pressure cleaning, the burr B may be removed by a technique such as rubbing a portion where the burr B occurs with a metal brush or the like.
[0033]
In the oil flow control valve 2 of this embodiment, as described above, since the sleeve 11 and the yoke 18 are formed as one integrated component, the number of components can be reduced.
Further, burrs B, which are a problem when the sleeve 11 and the yoke 18 are integrated, can be easily removed.
On the other hand, since the surface of the sleeve 11 is hardened, abrasion due to sliding of the spool 12 can be suppressed. For this reason, the durability of the spool valve 10 can be enhanced, and as a result, the durability of the oil flow control valve 2 can be enhanced, and the reliability of the variable valve timing device can be enhanced.
[0034]
(Modification)
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.
[0035]
In the above embodiment, an example in which the cylindrical spool 12 is used has been described. However, the structure of the spool 12 is not limited. For example, as in the related art, a shaft portion and a plurality of lands (large-diameter portions) are used. May be used.
In the above embodiment, a plurality of input / output ports (in the embodiment, the hydraulic supply port 11b, the advance chamber communication port 11c, the retard chamber communication port 11d, etc.) are provided by forming a radial through hole in the sleeve 11. Although the above example has been described, the structure of the sleeve 11 is not limited. For example, a plurality of input / output ports may be formed by forming a hole that does not penetrate the sleeve 11 as in the related art.
[0036]
In the above-described embodiment, an example in which the outer diameter of the moving core 14 is provided to be substantially the same as the outer diameter of the coil 17 has been described, but the outer diameter of the moving core 14 is provided smaller than the outer diameter of the coil 17. Is also good.
In the above-described embodiment, an example in which the spring 15 is disposed between the moving core 14 and the coil 17 has been described. However, the spring 15 may be disposed at another position such as between the moving core 14 and the stator 16. Is also good.
In the above embodiment, the spool 12 is displaced to the coil side when the coil 17 is turned on. However, the spool 12 may be displaced to the opposite coil side when the coil 17 is turned on.
[0037]
In the above-described embodiment, an example in which the oil flow control valve 2 to which the present invention is applied is combined with the variable valve timing mechanism 1 is shown. The present invention is applicable.
Further, in the above-described embodiment, an example in which the present invention is applied to the oil flow control valve 2 has been described. However, all the electric spool valves for switching the intermittent flow and the flow direction of another fluid (liquid, gas, etc.) instead of oil are described. The present invention may be applied to
[Brief description of the drawings]
FIG. 1 is a cross-sectional view along an axial direction of an oil flow control valve (embodiment).
FIG. 2 is a cross-sectional view of a sleeve showing a burr generation site (Example).
FIG. 3 is a schematic view of a variable valve timing device (Example).
FIG. 4 is a cross-sectional view along the axial direction of an oil flow control valve (conventional example).
FIG. 5 is a sectional view of a sleeve showing a burr generation site (conventional example).
[Explanation of symbols]
1 Variable valve timing mechanism 2 Oil flow control valve (electric spool valve)
5 Shoe housing (rotary drive)
6 Vane rotor (rotary follower)
7a advance chamber 7b retard chamber 10 spool valve 11 sleeve 11b hydraulic supply port (input / output port)
11c Leading chamber communication port (input / output port)
11d Delay chamber communication port (input / output port)
11e drain port (input / output port)
12 Spool 13 Electromagnetic actuator 14 Moving core 17 Coil 18 Yoke B Bali

Claims (3)

A sleeve in which an input / output port is formed, a spool valve including a spool that switches the input / output port by being displaced in an axial direction inside the sleeve,
A coil that generates a magnetomotive force when energized, a moving core coupled to the spool and driven by the magnetic force generated by the coil, an electromagnetic actuator including a yoke that covers the coil;
A method for manufacturing an electric spool valve comprising:
Forming the sleeve and the yoke integrally from a soft iron material;
A curing treatment step of performing a curing treatment on the surfaces of the integrated sleeve and yoke formed in this forming step,
A deburring step of removing burrs formed on the integrated sleeve and yoke after the curing step;
A method for manufacturing an electric spool valve, comprising: The method for manufacturing an electric spool valve according to claim 1,
A method of manufacturing an electric spool valve, wherein a thickness of a surface hardened layer applied in the hardening process is suppressed to 0.1 mm or less. The method for manufacturing an electric spool valve according to claim 1 or 2,
The electric spool valve,
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 driver and the rotary driven member, the camshaft is displaced to the advanced side together with the rotary driven member with respect to the rotary driver, 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 a variable mechanism hydraulic actuator,
A method of manufacturing an electric spool valve, comprising: 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.

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