Title of Invention

ELECTROMAGNETIC FLUID CONTROL VALVE

Abstract

An electromagnetic fluid control valve includes: a solenoid portion for generating electromagnetic attraction disposed inside an intake air pipe through which air flows; and a valve portion disposed integrally with the solenoid portion, the valve portion having a valve head that is placed in contact with and separated from a seat portion by the electromagnetic attraction, the seat portion being formed on an inner wall surface of the intake air pipe.

Full Text

ELECTROMAGNETIC FLUID CONTROL VALVE BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic fluid control valve in which a valve portion is operated by electromagnetic attraction generated in a solenoid portion to control flow rate of a fluid. 2. Description of the Related Art Conventionally, commonly-known examples of electromagnetic fluid control valves for controlling flow rate of air supplied to an engine include electronically-controlled throttle valves generally performing flow control using a disk-shaped butterfly valve. These throttle valves are driven by an electric motor via internal reduction gears, but their construction is complicated, the number of parts is large, and the product is also large. Since the actuation of the butterfly valve is via internal reduction gears, there has also been a limit to response time for maintaining a predetermined air flow rate relative to the rotational frequency of the engine and load fluctuations. In the past, these throttle valves were adopted only in medium-sized and larger vehicles, but recently consideration is also being given to mounting them to light vehicles and motorcycles, etc., having a small displacement, thereby increasing the demand for reductions in product size and for increased responsiveness. Idle speed control valves (hereinafter "ISC valves") for controlling idle rotational frequency of an engine are also known that are used together with throttle valves having a butterfly valve mechanically pulled in connection with accelerator operation, and are disposed in a bypass flow channel configured separately from the airflow channel controlled by the throttle valve. These ISC valves are flow rate control valves of an electromagnetic valve type in which a valve head is actuated directly by electromagnetic attraction, an amount of valve head lift for obtaining a supplied air flow rate required to maintain idling being controlled by a value of an electric current exciting the electromagnetic valve. (See Patent Literature 1, for example.) Patent Literature. Japanese Patent No. 3531334 (Gazette) However, since the above-mentioned ISC valves must be disposed in a bypass passage and a solenoid portion for generating electromagnetic attraction disposed outside piping, there is an L-shaped or U-shaped bend section in the pipelines before or after the valve head, and because the pressure loss there is large, one problem has been that it is difficult to increase the amount of through flow. Normally, in order to increase the flow rate, it is necessary to increase the amount of valve head lift or increase a diameter of a seat portion of the valve head to increase aperture surface area at the valve head, but if these must be unavoidably increased due to the above-mentioned problems of pressure loss in the piping, one resulting problem has been that it is necessary for the valve head also to be increased in size, increasing the size of the apparatus. Since pressure differences resulting from speed differences due to differences in the pathway length between a radially-inner side and a radially-outer side at the valve head are generated due to bends in the pipelines before and after the valve head, other problems have been that unintentional fluid dynamic forces act on the valve head, thereby making valve head action during lifting unstable, and accurate flow control becomes difficult if differences arise between the required amount of valve head lift and the actual amount of lift. SUMMARY OF THE INVENTION The present invention aims to solve the above problems and an object of the present invention is to provide an electromagnetic fluid control valve enabling more accurate flow control by eliminating a need for bends in piping before and after a valve head, thereby reducing pressure loss in the piping and stabilizing valve head action during lifting. In order to achieve the above object, according to one aspect of the present invention, there is provided an electromagnetic fluid control valve including: a solenoid portion for generating electromagnetic attraction disposed inside piping through which a fluid flows; and a valve portion disposed integrally with the solenoid portion, the valve portion having a valve head that is placed in contact with and separated from a seat portion by the electromagnetic attraction, the seat portion being formed on an inner wall surface of the piping. Using an electromagnetic fluid control valve according to the present invention, more accurate flow control is made possible by eliminating a need for bends in piping before and after a valve head, thereby reducing pressure loss in the piping and stabilizing valve action during lifting. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross section showing an electromagnetic fluid control valve according to Embodiment 1 of the present invention; Figure 2 is a cross section taken along line II - II in Figure 1 viewed in the direction of the arrows; Figure 3 is a cross section showing an electromagnetic fluid control valve according to Embodiment 2 of the present invention; Figure 4 is a cross section showing an electromagnetic fluid control valve according to Embodiment 3 of the present invention; and Figure 5 is a cross section taken along line V - V in Figure 4 viewed in the direction of the arrows. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be explained based on drawings, and identical or corresponding members and portions will be given identical numbering. Embodiment 1 Figure 1 is a cross section showing an electromagnetic fluid control valve (hereinafter "electromagnetic valve") according to Embodiment 1 of the present invention, and Figure 2 is a cross section taken along line II - II in Figure 1 viewed in the direction of the arrows. This electromagnetic valve includes: a solenoid portion 1 for generating electromagnetic attraction; and a valve portion 2 driven by this electromagnetic attraction. The solenoid portion 1 and the valve portion 2 are enveloped by a body 3 functioning as an intake air pipe. The body 3 constitutes a portion of an intake air pipe constituting piping, an upstream body portion 3a and a downstream body portion 3b being integrated by four bolts 21 with a gasket 17 and a plate 15 (described below) interposed. The body 3 is mounted coaxially to an intake air pipe partway along the intake air pipe to an engine (not shown). In the solenoid portion 1, a cylindrical core 4 is disposed so as to be coaxial with a central axis of the intake air pipe. A solenoid coil 5 is installed on an outer periphery of the core 4 by means of a bobbin 22. The solenoid coil 5 enveloped by a yoke 6. A cylindrical plunger 7 is disposed in an interior portion at a downstream end of the core 4 so as to be slidable in an axial direction. A penetrating aperture into which an adjusting screw 19 is screwed is formed at an upstream end of the core 4. This adjusting screw 19 is able to move forward and backward along the axis of the core 4 by rotation. The bobbin 22 is integrated with a connector 24 having terminals 23 using a resin. A radially-projecting flange portion 8 is formed on an end portion of the core 4 that is at a downstream end when the core is inserted into a penetrating aperture of the bobbin 22 and fixed. The yoke 6 and the core 4 are integrated simply by crimping an edge portion at an open end of the yoke 6 onto an outer peripheral edge portion of this flange portion 8. In the valve portion 2, a pipe 9 having communicating apertures 11 is fitted into and fixed to a penetrating aperture in the plunger 7. A valve head 10 having conducting apertures 13 is fixed to an end portion of the pipe 9 at a downstream end. A bellows 12 formed using a low-rigidity resin material and having a volume chamber in an interior portion is fixed to an upstream outer peripheral edge portion of the valve head 10. This bellows 12 has an axially-expandable concertina portion 25. A flange 27 is formed on an upstream end portion of the bellows 12, and this flange 27 is held between the flange portion 8 of the core 4 and a ring 26 press-fitted into a stepped portion at a downstream end of the flange portion 8. The volume chamber of the bellows 12 and interior portions of the core 4 and the plunger 7 all communicate with a negative pressure side of the engine via the conducting apertures 13 of the valve head 10 and the communicating aperture 11 of the pipe 9, making pressure generally equal at an upstream end surface and a downstream end surface of the plunger 7, and also making pressure generally equal on upstream surfaces and downstream surfaces of the valve head 10, thereby preventing actuation of the plunger 7 and the valve head 10 by pressure differences. An inner peripheral edge portion of a ring-shaped plate 15 having a plurality of passage apertures 16 having a total aperture surface area sufficiently larger than an aperture surface area of the valve head 10 is held between the flange portion 8 of the core 4 and the bobbin 22. An outer peripheral edge portion of this plate 15 is held between the upstream body portion 3a and the downstream body portion 3b. In an electromagnetic valve having the above configuration, peripheral edge portions of the plate 15 are held between the upstream body portion 3a and the downstream body portion 3b with the gasket 17 interposed with the solenoid portion 1, the valve portion 2, the bellows 12, and the plate 15 integrated with each other. At this time, the valve head 10 contacts a seat portion 18 formed on an inner wall surface of the downstream body portion 3b. Next, the valve head 10 is set to so as to obtain a predetermined amount of lift relative to the seat portion 18 by rotating the adjusting screw 19 to move the adjusting screw 19 forward or backward relative to the core 4 to adjust elastic force in a spring 20 disposed between the adjusting screw 19 and the pipe 9. Next, action of an electromagnetic valve of the above configuration will be explained. Until an electric current is passed through the solenoid coil 5, the valve head 10 is placed in contact with the seat portion 18 by the combined force of the spring 20 and the bellows 12. When an electric current is passed through the solenoid coil 5 via an electronic control unit (not shown), magnetic lines of force flow along a magnetic circuit constituted by the core 4, the yoke 6, and the plunger 7, generating a force in the core 4 proportional to the electric current value that attracts the plunger 7 away from the seat portion 18. Because of this, the plunger 7 is magnetically attracted to the core 4, the valve head 10 is lifted to a position of balance between the magnetic attraction and reaction due to the combined force of the spring 20 and the bellows 12, the pipe 9 and the valve head 10 integrated with the plunger 7 move in an axial direction, and as a result the valve head 10 is separated from the seat portion 18. At the same time, a pressure difference arises inside the intake air pipe due to negative pressure suction from the engine generated by operation of cylinders (not shown), and air inside the intake air pipe flows around the upstream body portion 3a and the yoke 6, around the passage apertures 16 of the plate 15 and the bellows 12, and through an outflow aperture 28 toward the engine. Here, because a proportional solenoid coil is used for the solenoid coil 5, the air flow rate through the outflow aperture 28 toward the engine is adjustable by controlling the electric current applied to the solenoid coil 5. The required air flow rate is determined by the degree of accelerator opening, rotational frequency of the engine, torque, etc. In an electromagnetic valve according to this embodiment, since the flow rate control valve for air supplied to an engine is a flow rate control valve using a valve head direct actuating construction based on electromagnetic attraction in contrast to conventional throttle valves dependent upon motors and speed reduction mechanisms, the construction thereof is simplified significantly, and the responsiveness of actuation of the valve head 10 is also improved. By disposing the solenoid portion 1 inside a pipeline so as to be coaxial with the flow, bends in the pipeline before and after the valve head 10 are eliminated, reducing pressure loss in the pipeline. For this reason, flow rate increases can be achieved compared to when there are bends in the pipeline, and the action of unstable fluid dynamic forces on the valve head 10 is reduced. In addition, because the solenoid portion 1 is disposed so as to be coaxial with the central axis of the intake air pipe, uniform fluid dynamic forces act on the valve head 10 in a circumferential direction, stabilizing actuation of the valve head 10. The solenoid portion 1 and the valve portion 2 integrated with the solenoid portion 1 are supported by the body 3 with the plate 15 interposed, and are positioned and fixed inside the intake air pipe by a simple construction. In addition, because air flows over outer peripheral surfaces of the yoke 6, there is a cooling effect due to forced-convection of the air that counters heat generated by the solenoid coil 5, enabling temperature increases in the solenoid coil 5 to be suppressed. Since the construction is such that the entire electromagnetic valve can be inserted into a portion of an intake air pipe by installing the solenoid portion 1 inside a pipeline, it is possible to achieve significant reductions in size, and mounting becomes possible comparatively easily even for different layouts such as mounting to other types of engine, etc. Since the valve head 10 is moved directly by electromagnetic attraction arising in the solenoid portion 1, responsiveness to control signals is good, and valve opening time is also short, and by disposing an electromagnetic valve according to this embodiment for each cylinder of an engine having a plurality of cylinders, for example, it is also possible to accurately control the amount of intake air sucked into each cylinder. Embodiment 2 Figure 3 is a cross section showing an electromagnetic fluid control valve according to Embodiment 2 of the present invention. In this embodiment, a guide portion 30 for guiding air toward inner wall surfaces of a body 3 is fixed to an upstream surface of a yoke 6. The rest of the configuration is similar to that of Embodiment 1. In this embodiment, air flowing toward the electromagnetic valve is guided toward the inner wall surfaces of the body 3 by the guide portion 30 and flows through the body 3 smoothly. Embodiment 3 Figure 4 is a cross section showing an electromagnetic fluid control valve according to Embodiment 3 of the present invention, and Figure 5 is a cross section taken along line V - V in Figure 4 viewed in the direction of the arrows. In this embodiment, a plate 32 having a guide portion 31 for guiding air toward inner wall surfaces of a body 3 and having a plurality of passage apertures 16 having a total aperture surface area sufficiently larger than an aperture surface area of a seat portion 18 is fixed to an upstream surface of a yoke 6. An outer peripheral edge portion of the plate 32 is held between an upstream body portion 3a and a downstream body portion 3b with a gasket 17 interposed. The rest of the configuration is similar to that of Embodiment 1. In this embodiment, air flowing toward the electromagnetic valve is guided toward the inner wall surfaces of the body 3 by the guide portion 31 of the plate 32 and flows through the body 3 smoothly. Moreover, in each of the above embodiments, an electromagnetic valve is disposed so as to be coaxial with an intake air pipe, but of course this electromagnetic valve can also be used as an ISC valve. In each of the above embodiments, cases in which the present invention is mounted such that the airflow direction is from the solenoid portion 1 toward the valve head 10 have been explained, but the present invention may also be mounted such that the airflow direction is reversed, flowing from the valve head 10 toward the solenoid portion 1. Here, the former case has an advantage in that if the wires of the solenoid coil 5 break, the valve head 10 is reliably closed by the elastic forces of the spring 20 and the bellows 12 and fluid dynamic forces, and the latter case has an advantage in that incompletely-combusted substances from the engine can be prevented from passing through the conducting apertures 13 and flowing into interior portions of the bellows 12, and which one to select can be determined according to the service conditions. In each of the above embodiments, an electromagnetic valve is disposed inside a body 3 constituting a portion of an intake air pipe functioning as piping, but this electromagnetic valve can also be mounted inside an air discharge pipe, for example, functioning as piping, and used as an exhaust gas recycling valve (EGR valve). WHAT IS CLAIMED IS: 1. An electromagnetic fluid control valve comprising: a solenoid portion for generating electromagnetic attraction disposed inside piping through which a fluid flows; and a valve portion disposed integrally with said solenoid portion, said valve portion having a valve head that is placed in contact with and separated from a seat portion by said electromagnetic attraction, said seat portion being formed on an inner wall surface of said piping. 2. The electromagnetic fluid control valve according to Claim 1, wherein: said solenoid portion and said valve portion are disposed on a central axis of said piping. 3. The electromagnetic fluid control valve according to either of Claims 1 or 2, wherein: said solenoid portion and said valve portion are supported in said piping by means of a plate having a passage aperture penetrating through in a plate thickness direction through which said fluid passes. 4. The electromagnetic fluid control valve according to any one of Claims 1 to 3, wherein: said solenoid portion has: a core; a solenoid coil disposed outside said core; and a cup-shaped yoke covering said solenoid coil; said valve portion has a plunger integrated with said valve head so as to be slidable relative to said core; and said yoke and said core are integrated by crimping an open end portion of said yoke onto an outer peripheral edge portion of said core. 5. The electromagnetic fluid control valve according to any one of Claims 1 to 4, wherein: a guide portion for guiding said fluid toward an inner wall surface of said piping is fixed to an upstream surface of said yoke. 6. The electromagnetic fluid control valve according to either of Claims 3 or 4, wherein: said plate has a guide portion for guiding said fluid toward an inner wall surface of said piping, and is fixed to an upstream surface of said yoke. 7. The electromagnetic fluid control valve according to any one of Claims 1 to 6, wherein: said fluid is air; and said piping is an intake air pipe for directing said air to an engine. 8. The electromagnetic fluid control valve according to Claim 7, wherein: a plurality of said electromagnetic fluid control valves are disposed on said engine. 9. The electromagnetic fluid control valve according to Claim 7, wherein: one electromagnetic fluid control valve is disposed for each cylinder of said engine.

Documents:

0922-che-2005-abstract.pdf

0922-che-2005-claims.pdf

0922-che-2005-correspondnece-others.pdf

0922-che-2005-description(complete).pdf

0922-che-2005-drawings.pdf

0922-che-2005-form 1.pdf

0922-che-2005-form 3.pdf

0922-che-2005-form 5.pdf

0922-che-2005-others.pdf

922-CHE-2005 EXAMINATION REPORT REPLY RECEIVED 08-03-2012.pdf

922-CHE-2005 FORM-3 08-03-2012.pdf

922-CHE-2005 AMENDED CLAIMS 08-03-2012.pdf

922-CHE-2005 CORRESPONDENCE OTHERS.pdf

922-CHE-2005 CORRESPONDENCE PO.pdf