JP2005256639A - Solenoid-operated fuel injection valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively suppress operating sound while ensuring sufficient strength to obtain reliability of an electric connection part and attaining miniaturization in a solenoid-operated fuel injection valve provided with a resin molded part made of synthetic resin, embedding at least a part of a solenoid housing and integrally having an initial power receiving coupler with a receiving side connection terminal facing and connected to a coil of a coil assembly. <P>SOLUTION: The resin molded part 7 is formed of two layers which are a first resin molded layer 7a forming at least a part of the initial power receiving coupler 40 while covering at least the part of the solenoid housing 25, and a second resin molded layer 7b formed of material having a larger linear expansion coefficient than the first resin molded layer 7a and covering the first resin molded layer 7a. An air layer 44 is partially formed between the first and second resin molded layers 7a, 7b. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electromagnetic fuel injection valve, and in particular, a valve operating portion in which a valve body that is spring-biased in a direction of seating on the valve seat is housed in a valve housing having a valve seat at a front end, and the valve seat A coil assembly capable of exerting an electromagnetic force for driving the valve body on the side to be separated from the solenoid housing housed in a solenoid housing connected to the valve housing; and a power reception connected to the coil of the coil assembly The present invention relates to an electromagnetic fuel injection valve that includes a synthetic resin-made resin molding portion that integrally includes a power receiving coupler that faces a side connection terminal and that embeds at least a part of the solenoid housing.

In such an electromagnetic fuel injection valve, the entire fuel injection valve is covered with a rubber soundproof cover in order to suppress the generation of operation noise (see Patent Document 1), or a part of the solenoid housing. There is already known a structure in which a vibration isolator that covers the substrate is further covered with a resin molded part having a coupler (see Patent Document 2).
Japanese Patent Laid-Open No. 62-195542 JP-A-63-41658

  As disclosed in the above-mentioned Patent Document 1, if the entire injection valve is covered with a soundproof cover, the entire fuel injection valve is enlarged, and the arrangement space of the electromagnetic fuel injection valve is limited, for example, in a motorcycle. Is difficult to apply. Further, the one disclosed in Patent Document 2 has a two-layer structure of a vibration isolator and a resin molded part, but the coupler has a relatively high strength for improving the reliability of the electrical connection part. In general, the resin molded part is formed of a synthetic resin such as PA66 containing glass fiber. However, although PA66 has a low coefficient of linear expansion and a relatively high hardness, it is possible to increase the reliability of the electrical connection part, but the glass fiber in the resin molded part easily transmits sound. Even though the solenoid housing is partially covered with the two-layer structure of the vibration isolator and the resin molded portion, the effect of suppressing the operation noise is low.

  The present invention has been made in view of such circumstances, and effectively suppresses the generation of operating noise while ensuring sufficient strength to obtain the reliability of the electrical connection portion, and further enables downsizing. An object is to provide an electromagnetic fuel injection valve.

  In order to achieve the above object, the invention according to claim 1 is a valve actuating portion in which a valve body that is spring-biased in a direction of seating on the valve seat is accommodated in a valve housing having a valve seat at a front end. A coil assembly capable of exerting an electromagnetic force for driving the valve body on the side away from the valve seat is accommodated in a solenoid housing connected to the valve housing, and a coil of the coil assembly In the electromagnetic fuel injection valve, the resin molded portion includes a synthetic resin-made resin molded portion that integrally includes a power receiving coupler that faces a power receiving side connection terminal connected to the at least a portion of the solenoid housing. Is formed of a first resin molding layer that covers at least a part of the solenoid housing and constitutes a part of the power receiving coupler, and a material having a larger linear expansion coefficient than the first resin molding layer And the second resin molding layer covering the first resin molding layer is formed by two-layer molding, and an air layer is partially formed between the first and second resin molding layers. Fuel injection valve.

  In addition to the configuration of the invention described in claim 1, the second aspect of the invention is such that the second resin molding layer has a thick portion at the center and a thick portion that is thinner than the thick portion. The thin-walled portion is engaged with the first resin molding layer or the metal member in a concavo-convex manner.

  According to a third aspect of the present invention, in addition to the configuration of the second aspect of the invention, the outer surface of the first resin molding layer is formed to be rougher than other portions in the vicinity of the concave-convex engagement portion with the thin portion. It is characterized by being.

  The invention according to claim 4 is characterized in that, in addition to the configuration of the invention according to any one of claims 1 to 3, the first resin molding layer is formed of a liquid crystal polymer mixed with glass fibers. .

  Furthermore, in the invention according to claim 5, in addition to the structure according to any one of claims 1 to 4, the second resin molding layer is formed of a thermoplastic polyester elastomer from which glass fibers are not mixed. It is characterized by.

  According to the first aspect of the present invention, the resin molding portion has a two-layer structure including the first resin molding layer and the second resin molding layer, and the first resin molding layer is a synthetic resin having a relatively small linear expansion coefficient. Therefore, the connection portion of the coil assembly and the power receiving side connection terminal is covered with the first resin molding layer, and at least a part of the power receiving coupler is formed of the first resin molding layer. Since the second resin molding layer that covers the first resin molding layer is formed of a flexible synthetic resin having a relatively large linear expansion coefficient, the resin molding portion can have a strength that can ensure reliability. Due to the flexibility of the second resin molding layer, it is possible to effectively suppress the generation of operating noise, and an air layer is partially formed between the first and second resin molding layers, so that the operating noise can be transmitted. Further suppression can be achieved. And compared with what covers the whole fuel injection valve with a soundproof cover, the whole electromagnetic fuel injection valve can be made compact.

  According to the invention described in claim 2, by changing the thickness of the second resin molding layer depending on the part, the amount of shrinkage at the time of cooling immediately after molding is partially changed, and air is formed around the thick part. Layers can be formed automatically. That is, the thin-walled portion on the end side has a relatively high cooling rate, and the degree of adhesion to the first resin molding layer or the metal member is increased by the concave-convex engagement, so that the amount of shrinkage can be suppressed, and the thickness of the central portion Since the cooling rate of the meat portion is relatively slow and the amount of shrinkage is relatively large, the central portion of the second resin molding layer is gently lowered while suppressing the shrinkage on the terminal side of the second resin molding layer by the uneven engagement. It is possible to form the air layer by cooling it to a relatively large size and contracting.

  According to invention of Claim 3, the adhesiveness to the 1st resin molding layer of the terminal side of a 2nd resin molding layer can be improved, and shrinkage | contraction of the 2nd resin molding layer after two-layer molding is suppressed. The quality can be improved.

  According to the fourth aspect of the present invention, the liquid crystal polymer has a function of relatively suppressing the transmission of the operating sound and has a high rigidity, so that the strength for ensuring the reliability of the electrical connection portion is further increased. In addition, it is possible to more effectively suppress the generation of operating noise.

  Furthermore, according to the invention described in claim 5, the thermoplastic polyester elastomer from which glass fibers are not mixed has excellent elasticity, and it is possible to effectively suppress the generation of operating noise.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

  First, referring to FIG. 1, an electromagnetic fuel injection valve for injecting fuel into an engine (not shown) is a valve body which is spring-biased in a direction in which the valve seat 8 has a valve seat 13 at the front end thereof. And a solenoid housing in which a coil assembly 24 capable of exerting an electromagnetic force for driving the valve body 20 on the side separated from the valve seat 13 is connected to the valve housing 8. 25. The solenoid assembly 6 accommodated in the coil assembly 25 and the power receiving coupler 40 that faces the power receiving side connection terminals 38 connected to the coil 30 of the coil assembly 24 are integrated with at least the coil assembly 24 and the solenoid housing. And resin molding part 7 made of synthetic resin in which 25 is embedded.

  The valve housing 8 includes a magnetic cylinder 9 made of magnetic metal and a valve seat member 10 that is liquid-tightly coupled to the front end of the magnetic cylinder 9. The valve seat member 10 is welded to the magnetic cylinder 9 with its rear end fitted to the front end of the magnetic cylinder 9, and the valve seat member 10 opens to the front end surface thereof. A fuel outlet hole 12, a tapered valve seat 13 connected to the inner end of the fuel outlet hole 12, and a guide hole 14 connected to the rear end large diameter portion of the valve seat 13 are provided coaxially. A steel plate injector plate 16 having a plurality of fuel injection holes 15 leading to the fuel outlet hole 12 is welded to the front end of the valve seat member 10 in a liquid-tight manner.

  A movable core 18 constituting a part of the solenoid portion 6 is slidably fitted to the rear portion of the valve housing 8, and the valve seat is connected to the front end of the valve shaft 19 integrally connected to the movable core 18. A valve body 20 that can be seated on 13 and close the fuel outlet hole 12 is integrally formed. In the movable core 18, the valve shaft 19 and the valve body 20, a through hole 21 communicating with the inside of the valve housing 8 is formed coaxially with a bottomed shape with the front end closed.

  The solenoid unit 6 includes the movable core 18, a cylindrical fixed core 22 that faces the movable core 18, and a return spring 23 that exerts a spring force that biases the movable core 18 toward the side away from the fixed core 22. The coil is arranged so as to surround the rear portion of the valve housing 8 and the fixed core 22 while enabling to exert an electromagnetic force that attracts the movable core 18 toward the fixed core 22 against the spring force of the return spring 23. An assembly 24 and a solenoid housing 25 surrounding the coil assembly 24 so that the front end portion is connected to the valve housing 8 are provided.

  The rear end of the magnetic cylinder 9 in the valve housing 8 is coaxially coupled to the front end of the fixed core 22 via a nonmagnetic cylinder 26 formed of a nonmagnetic metal such as stainless steel. The rear end of the body 9 is butt welded to the front end of the nonmagnetic cylindrical body 26, and the rear end of the nonmagnetic cylindrical body 26 is fixed to the fixed core 22 with the front end of the fixed core 22 fitted to the nonmagnetic cylindrical body 26. Welded to.

  A cylindrical retainer 27 is coaxially fitted and fixed by caulking to the fixed core 22, and the return spring 23 is interposed between the retainer 27 and the movable core 18. A ring-shaped stopper 28 made of a non-magnetic material is provided from the rear end surface of the movable core 18 to the inner periphery of the rear end portion of the movable core 18 so as to avoid the movable core 18 from directly contacting the fixed core 22. It is fitted and fixed so that it protrudes slightly to the side. Further, the coil assembly 24 is formed by winding a coil 30 around a bobbin 29 surrounding the rear portion of the valve housing 8, the nonmagnetic cylindrical body 26 and the fixed core 22.

  The solenoid housing 25 has an annular end wall 31a facing the end of the coil assembly 24 on the side of the valve operating portion 5 at one end, and has a cylindrical shape surrounding the coil assembly 24 and is formed of a magnetic metal. 31 and a flange portion 22a projecting radially outward from the rear end portion of the fixed core 22 and facing the end portion of the coil assembly 24 opposite to the valve operating portion 5. 22 a is magnetically coupled to the other end of the magnetic frame 31. In addition, a fitting cylinder portion 31b for fitting the magnetic cylinder body 9 in the valve housing 8 is coaxially provided on the inner periphery of the end wall 31a of the magnetic frame 31, and the solenoid housing 25 is provided with the fitting cylinder portion. The valve housing 8 is connected to the valve housing 8 by fitting the valve housing 8 to 31b.

  A cylindrical inlet cylinder 33, which is a metal member, is integrally and coaxially connected to the rear end of the fixed core 22, and a fuel filter 34 is attached to the rear part of the inlet cylinder 33. Moreover, the inlet tube 33, the retainer 23, and the fixed core 22 are provided with a fuel passage 35 that communicates with the through hole 21 of the movable core 18 in a coaxial manner.

  The resin molding portion 7 fills not only the solenoid housing 25 and the coil assembly 24 but also a part of the valve housing 8 and most of the inlet cylinder 33 while filling the gap between the solenoid housing 25 and the coil assembly 24. In the magnetic frame 31 of the solenoid housing 25, a notch portion 36 for arranging an arm portion 29 a formed integrally with the bobbin 29 of the coil assembly 24 outside the solenoid housing 25 is formed. Provided.

  The resin molding portion 7 is integrally provided with a power receiving coupler 40 facing the power receiving side power receiving side connection terminals 38 connected to both ends of the coil 30 in the coil assembly 24, and the power receiving side connection terminal 38. Are embedded in the arm portion 29a, and the coil ends 30a of the coil 30 are welded to the power receiving side connection terminals 38.

  By the way, the resin molding part 7 covers at least a part of the solenoid housing 25 and forms a part of the power receiving coupler 40, and a second resin molding layer covering the first resin molding layer 7a. In this embodiment, the entire solenoid housing 25, the rear part of the valve housing 8 and a part of the inlet tube 33 are covered with the first resin molding layer 7a and a part of the power receiving coupler 40 is formed. It is formed with the first resin molding layer 7a.

  Moreover, the first resin molding layer 7a is formed of a material having a relatively high bending strength, for example, a liquid crystal polymer mixed with glass fibers, whereas the second resin molding layer 7b has a bending strength of the first resin molding. It is formed of a material smaller than the layer 7a, for example, a thermoplastic polyester elastomer that excludes the mixing of glass fibers, such as the trade name Hytrel (DuPont, USA).

  By the way, the relationship between the bending strength when the entire resin molded part 7 is formed of a liquid crystal polymer mixed with 35% glass fiber, for example, and the operating sound pressure peak generated from the resin molded part 7 is shown by a point A in FIG. The liquid crystal polymer has a function of relatively suppressing transmission of operating sound and is also highly rigid. On the other hand, when the entire resin molded part 7 is formed of a thermoplastic polyester elastomer that excludes glass fibers, the generation of operating noise can be effectively suppressed by the excellent flexibility of the thermoplastic polyester elastomer. As shown by the point B in FIG. 2, the operating sound pressure peak can be kept low although the bending strength is smaller than that of the liquid crystal polymer.

  The second resin molding layer 7b is composed of a thick portion 7ba at the center thereof and thin portions 7bb, 7bc, 7bd on the end side continuous with the thick portion as being thinner than the thick portion 7ba. 7bd is engaged with the first resin molding layer 7a or the inlet cylinder 33, which is a metal member, in an uneven manner.

  That is, the first resin molding layer 7a is not covered with the second resin molding layer 7b from the intermediate portion of the power receiving coupler 40 to the front end side, and is exposed to the outside, and the rear portion of the inlet cylinder 33 is the second resin molding layer. 7b is exposed to the outside without being covered with 7b, and a part of the first resin molding layer 7a is exposed to the outside without being covered with the second resin molding layer 7b at a portion corresponding to the rear portion of the valve housing 8. ing. Thus, the end portions of the thin portions 7bb and 7bd of the second resin molding layer 7b are engaged with the first resin molding layer 7a at the middle portion of the power receiving coupler 40 and the portion corresponding to the rear portion of the valve housing 8. Endless engagement grooves 41, 42 are formed, and an engagement protrusion 43 that engages with the inner surface of the thin portion 7 bc of the second resin molding layer 7 b is provided on the outer periphery of the intermediate portion of the inlet tube 33. In addition, the outer surface of the first resin molding layer 7a is formed to be rougher than the other portions by forming a wrinkle pattern, corrugated irregularity molding, or the like in the vicinity of the concave-convex engaging portion with the thin-walled portions 7bb, 7bd.

  Next, the operation of this embodiment will be described. The resin molding portion 7 includes a first resin molding layer 7a that covers at least a part of the solenoid housing 25 and constitutes a part of the power receiving coupler 40, and a first resin molding layer. A second resin molding layer 7b formed of a material having a larger linear expansion coefficient than 7a and covering the first resin molding layer 7a is formed in two layers.

  Therefore, the connection portion between the coil 30 and the power receiving side connection terminals 38 of the coil assembly 24 is covered with the first resin molding layer 7a, and the main portion of the power receiving coupler 40 is formed with the first resin molding layer 7a. The resin molding part 7 can be provided with a strength capable of ensuring the reliability of the part. Further, since the second resin molding layer 7b covering the first resin molding layer 7a is formed of a synthetic resin having a relatively large linear expansion coefficient, it is possible to effectively suppress the generation of operating noise. Since the air layer 44 is partially formed between the second resin molding layers 7a and 7b, the transmission of the operating sound can be further suppressed. In addition, the entire electromagnetic fuel injection valve can be made compact as compared with a case where the entire fuel injection valve is covered with a soundproof cover.

  Moreover, the first resin molding layer 7a is formed of a liquid crystal polymer mixed with glass fiber, and the liquid crystal polymer mixed with glass fiber has a function of relatively suppressing transmission of operating sound, and has high rigidity. However, it is possible to further increase the strength for ensuring the reliability of the electrical connection portion, and to more effectively suppress the generation of operating noise.

  The second resin molding layer 7b is formed of a thermoplastic polyester elastomer from which glass fibers are not mixed. Since the thermoplastic polyester elastomer from which glass fibers are not mixed has excellent elasticity, the operation sound Can be effectively suppressed.

  The second resin molding layer 7b is composed of a thick portion 7ba at the center thereof, and thin portions 7bb, 7bc, 7bd on the end side continuous with the thick portion 7ba as being thinner than the thick portion 7ba. , 7bd are engaged with the first resin molding layer 7a in a portion corresponding to the intermediate portion of the power receiving coupler 40 and the rear portion of the valve housing 8, and a thin portion is formed in the intermediate portion of the inlet tube 33 integral with the fixed core 22. Since 7bc is engaged with the concave and convex portions, by changing the thickness of the second resin molding layer 7b depending on the part, the amount of shrinkage during cooling immediately after molding is partially changed, and the peripheral portion of the thick part 7ba is The air layer 44 can be formed automatically.

  That is, the thin-walled portions 7bb-7bd on the end side have a relatively high cooling rate, and the degree of close contact with the first resin molding layer 7 or the inlet tube 33 is increased by the concave-convex engagement, so that the amount of shrinkage can be kept small. In addition, the central thick portion 7ba has a relatively slow cooling rate and a relatively large shrinkage amount. Therefore, the second resin can be prevented from contracting on the terminal side of the second resin molding layer 7b by the uneven engagement. The air layer 44 can be formed in the peripheral portion of the thick portion 7ba by slowly cooling the central portion of the molding layer 7b and contracting it relatively greatly.

  Moreover, since the outer surface of the first resin molding layer 7a is formed to be rougher than the other portions in the vicinity of the concave-convex engaging portions with the thin portions 7bc, 7bd, the first resin on the terminal side of the second resin molding layer 7b is formed. The adhesiveness to the molding layer 7a can be enhanced, and the quality can be improved by suppressing the shrinkage of the second resin molding layer 7b after the two-layer molding.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.

It is a longitudinal cross-sectional view of an electromagnetic fuel injection valve. It is a figure which shows the relationship between the linear expansion coefficient and the operating sound pressure peak of the liquid crystal polymer and thermoplastic polyester elastomer which mixed glass fiber.

Explanation of symbols

DESCRIPTION OF SYMBOLS 5 ... Valve operation part 6 ... Solenoid part 7 ... Resin molding part 7a ... 1st resin molding layer 7b ... 2nd resin molding layer 7ba ... Thick part 7bb, 7bc, 7bd ... Thin portion 8 ... Valve housing 13 ... Valve seat 20 ... Valve body 24 ... Coil assembly 25 ... Solenoid housing 30 ... Coil 38 ... Power receiving side connection terminal 40 ... Receiving coupler 44 ... Air layer

Claims (5)

  A valve operating part (5) in which a valve body (20) spring-biased in a direction of seating on the valve seat (13) is accommodated in a valve housing (8) having a valve seat (13) at the front end; In a solenoid housing (25) in which a coil assembly (24) capable of exerting electromagnetic force for driving the valve body (20) on the side to be separated from the valve seat (13) is connected to the valve housing (8). A solenoid unit (6) housed in the coil assembly and a power receiving coupler (40) facing the power receiving side connection terminal (38) connected to the coil (30) of the coil assembly (24). In the electromagnetic fuel injection valve comprising a synthetic resin resin molded part (7) for embedding a part of the housing (25), the resin molded part (7) is at least a part of the solenoid housing (25). Covering and receiving A first resin molding layer (7a) constituting a part of the coupler (40), and a first resin molding layer (7a) formed of a material having a larger linear expansion coefficient than the first resin molding layer (7a). A second resin molding layer (7b) to be covered is formed by two-layer molding, and an air layer (44) is partially formed between the first and second resin molding layers (7a, 7b). An electromagnetic fuel injection valve.   The second resin molding layer (7b) has a thick part (7ba) at the center thereof and a thin part (7bb, 7bc on the terminal side continuous to the thick part (7ba) as being thinner than the thick part (7ba). 7bd), and the thin-walled portion (7bb-7bd) is unevenly engaged with the first resin molding layer (7a) or the metal member (33). Injection valve.   The outer surface of said 1st resin molding layer (7a) is formed in a rough surface rather than another part in the uneven | corrugated engagement part vicinity with the said thin part (7bb, 7bd), The other surface is formed. Electromagnetic fuel injection valve.   The electromagnetic fuel injection valve according to any one of claims 1 to 3, wherein the first resin molding layer (7a) is formed of a liquid crystal polymer mixed with glass fibers.   The electromagnetic fuel injection valve according to any one of claims 1 to 4, wherein the second resin molding layer (7b) is formed of a thermoplastic polyester elastomer from which glass fibers are not mixed.

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