JPH02127935A - Coupling method for each hollow cylindrical body and valve body of solenoid valve manufactured by its coupling method - Google Patents

Abstract

PURPOSE:To improve the assembly accuracy of each hollow cylindrical body by coupling each cylindrical body by using a plastic flow by local pressure, and constraining and supporting one of the hollow cylindrical bodies by two parts of a plastic flow of the other and a taper. CONSTITUTION:One end outside periphery of the other hollow cylindrical body (guide ring) 8B is fitted to one end inside periphery of one metallic hollow cylindrical body (plunger) 7A. Subsequently, the vicinity of the fitting part of the hollow cylindrical body 7A is pressurized 7a locally and brought to plastic flow 7b, and both the hollow cylindrical bodies 7A, 8B are coupled to each other by autofrettage force. Also, in a part of the inside periphery of the hollow cylindrical body 7A, a taper 7C is formed in advance, and this taper 7C surface receives the end face of the hollow cylindrical body 8B in a press-contacting state under the coupling state of both the hollow cylindrical bodies 7A, 8B. In such a way, the assembly accuracy of each hollow cylindrical body can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of joining hollow cylindrical bodies such as pipe materials, ring materials, etc. that fit together, and a method of manufacturing using this joining method. Regarding the valve body of a solenoid valve.

[Conventional technology]

Conventionally, press-fitting methods, press-fitting methods, and the like have been widely adopted as techniques for joining cylindrical bodies. Among these, the press-fitting method is evaluated as having a higher bonding strength than the press-fitting method and the like.

An example of the press-fitting method is Japanese Patent Publication No. 11071/1983.

As disclosed in Japanese Unexamined Patent Application Publication No. 135661/1983, it is used in a technology for connecting a plunger (movable core) of an electromagnetic fuel injection valve and a two-dollar valve. In this method, for example, a groove or a protrusion is formed on one end of the outer periphery of the needle valve, one end of the outer periphery of the needle valve is fitted to the inner periphery of a hollow cylindrical plunger, and then the outer periphery of the plunger is press-fitted. The plunger is plastically deformed so that the inner circumference of the plunger bites into a groove on the outer circumference of the needle valve or is caulked onto a protrusion.

By the way, in this press-fitting method, grooves, protrusions, etc. are processed on the outer periphery of one of the objects to be connected (the needle valve in the above example). In the case of a hollow cylindrical body such as a ring member, it is difficult to process grooves or protrusions. That is, if a groove is cut in a thin tube material, there is a risk that the groove will be cut during press fitting, and it is impossible to form the protrusion itself due to the shape characteristics.

Therefore, recently, when connecting hollow cylindrical bodies such as when one of the hollow cylinders is thin, a joining method using plastic flow generated by localized pressure has been proposed instead of the press-fitting method. In this method, one end of the outer periphery of the other hollow cylindrical body B (for example, a thin one) is fitted to one end of the inner periphery of one hollow cylindrical body A, and after this fitting, the end surface on the side of the hollow cylindrical body A is fitted. A local pressing force is applied near the part to generate plastic flow around the pressed part, and the self-tensioning force (residual compressive stress) caused by this plastic flow connects the hollow cylinders.

In addition, as an example of coupling between hollow cylinders, for example,
As disclosed in Japanese Patent No. 3-111280, there is an example of a coupling between a plunger and a guide ring that constitute a part of a valve body (movable valve) of an electromagnetic fuel injection valve. The wall thickness of the guide ring in this case is extremely thin, for example, about 0.4 μm.

This joining technology that utilizes plastic flow caused by localized pressure does not require the provision of grooves or protrusions on one hollow cylindrical body unlike the press-fitting method, and moreover, it only applies pressure locally to the end face of the hollow cylindrical body. , there is no deformation other than the local press marks left on the pressurized part, so there is no overall deformation after the joining process like in the press fitting method, and the positional accuracy is maintained even after the joining process, so accuracy can be maintained. It has the advantage of not requiring any post-processing.

[Problem to be solved by the invention]

By the way, in the conventional joining technology of hollow cylindrical bodies that utilizes plastic flow due to localized pressure, the outer periphery of the other hollow cylindrical body B that is fitted onto the inner periphery of one hollow cylindrical body A is only at the part where the plastic flow occurs. This is a so-called one-point support structure. In such a one-point support structure, when a lateral load is applied to the hollow cylinder B,
The supporting strength is not necessarily sufficient, and the hollow cylinder is likely to be tilted or damaged. Note that lateral loads are likely to be applied from the outside, for example, during product assembly or secondary work performed after the hollow cylinders are joined together.

The present invention has been made in view of the above points, and its purpose is to improve the strength against lateral loads even when hollow cylindrical bodies are connected using plastic flow due to local pressurization. Moreover, it is an object of the present invention to provide a method for connecting hollow cylindrical bodies with each other that can improve assembly accuracy, and a valve body of a solenoid valve manufactured using this method.

[Means to solve the problem]

The above purpose is to fit the outer periphery of one end of the other hollow cylindrical body B to the inner periphery of one end of one metal hollow cylindrical body A to be joined, and to fit the outer periphery of one end of the other hollow cylindrical body B to the inner periphery of one end of the metal hollow cylindrical body A to be coupled, and to fit the outer periphery of one end of the hollow cylindrical body B to the inner periphery of one end of the hollow cylindrical body is locally pressurized to cause plastic flow, and the self-tightening force around the pressurized part generated by this plastic flow connects hollow cylinders A and B, and a part of the inner circumference of hollow cylinder A is previously formed with a taper. This is achieved by making this tapered surface press against the end surface of the hollow cylinder B under the state in which the hollow cylinders A and B are connected.

[Effect]

In order to facilitate understanding, the operation of the present invention will be explained with reference to the drawing of the embodiment shown in FIG.

The embodiment shown in FIG. 1 shows a combination of a plunger 7 of a solenoid valve (for example, a fuel injection valve) and a guide ring 8, and the plunger 7 will be described as a hollow cylinder A and the guide ring 8 as a hollow cylinder B.

Reference numeral 7a indicates a press mark after locally pressurizing the end surface of the hollow cylinder A in the vicinity of the fitting part of the cylinder, and 7b indicates a plastic flow part produced by this. In addition, 7c is a hollow cylinder A
This is a taper formed on a part of the inner periphery.

In the present invention, the self-tightening force of the plastic flow (
Residual compressive stress) acts on the outer periphery of the hollow cylindrical body B, and the hollow cylindrical bodies are bonded to each other.

In addition, the taper 7c receives the outer periphery of one end of the hollow cylindrical body B in a press-contact state. When the taper 7c receives the outer periphery of one end of the hollow cylindrical body B, the force of the plastic flow 7b generated during the joining process acts downward in the drawing, and this force acts on the outer periphery of the hollow cylindrical body B. As a result, the outer periphery of one end of the hollow cylindrical body B comes into extremely strong pressure contact with the taper 7c, and as a result, sufficient compressive stress acts from the taper 7c on the press-contact location of the hollow cylindrical body B.

The compressive stress from this taper 7c acts like a self-tightening force.

G is a gap between the hollow cylinders A and B that is generated when the hollow cylinder B is deformed by the force of plastic flow.

According to the present invention, even if a gap G occurs, the outer periphery of the hollow cylindrical body B is fixedly supported by the plastic flow portion 7b and the taper 7c at the inner periphery on the hollow cylindrical body A side, and the connection Increase strength. Moreover, since the plastic flow portion 7b and the taper 7c can adopt a two-point support structure with a gap between them at the fitting location,
The strength of the hollow cylindrical body B against bending moments due to lateral loads can be increased.

The members of the hollow cylindrical bodies A and B are preferably those whose linear expansion coefficients are the same or close to each other in order to maintain the self-tensioning force of plastic flow and pressure support of the taper. That is, by using materials with the same or similar linear expansion coefficients, it is possible to maintain the invariance of the strength for one bending moment of the joint strength even if the ambient temperature changes.

Further, according to the present invention, since the taper 7c functions to center the hollow cylinder B, the hollow cylinder B and the hollow cylinder A
It is possible to improve coaxiality with

〔Example〕

Embodiments of the present invention will be described based on the drawings.

1 and 4 to 6 show one embodiment of the present invention, and exemplify an electromagnetic fuel injection valve as an application target.

FIG. 1 is a partially enlarged sectional view showing the coupled state of the guide ring 8 and plunger 7, which constitute a part of the valve body of the fuel injection valve, FIG. 4 is an overall sectional view of the fuel injection valve, and FIG. FIG. 6, which is a partial cross-sectional view of the valve body, is an explanatory diagram showing a part of the manufacturing process of the valve body.

First, an overview of the fuel injection valve will be explained based on Fig. 4.
1 is a cylindrical yoke that becomes the injection valve body, 2 is a fixed core,
3 is an electromagnetic coil wound around an insulating bobbin 4; 5 is a valve body (
(movable valve). The valve body 5 is formed by integrally assembling a ball 6, a plunger 7, a guide ring 8, etc., which serve as a valve part.

In this valve body 5, a plunger 7 is formed by integrally molding a hollow cylindrical portion 7-1 and a rod portion 7-2, and a ball 6 is welded to one end of the rond portion 7-2. Further, a hollow cylindrical guide ring 8 is coupled to the inner periphery of the hollow cylindrical portion 7-1 by plastic flow. This plastic flow coupling will be described later.

The fixed core 2 and the electromagnetic coil 3 are fixedly arranged concentrically within the yoke 1. Further, a valve body 5 is installed in a fuel passage 9 formed at the center of the lower part of the yoke 1 so as to be able to reciprocate in the axial direction of the yoke 1, with a plunger facing one end of the core 2. A part of the guide ring 8 of the valve body 5 is fitted in a guide hole 10 provided at the center of the lower end of the core 2 so as to be able to reciprocate. A return spring 12 is inserted between the adjusting rod 11 and the guide ring 8 and interposed therebetween.

Reference numeral 13 denotes a nozzle having an injection port 13a, which is attached to the lower end of the yoke 1. A valve seat 14 is formed inside the nozzle 13 to correspond to the ball 6, and a fuel swirler 15 having a valve guide hole 15a at an upstream position of the valve seat 14 is connected to the nozzle 13.
are arranged concentrically.

In such an electromagnetic fuel injection valve, when a current is applied to the electromagnetic coil 3 via the connector 16, the yoke 1. Core 2. The plunger 7 and the coil 3 form a magnetic circuit, and the plunger 7 and thus the valve body 5 are magnetically attracted to the core 2 side against the force of the spring 12. As a result, the ball 6 separates from the valve seat 14, and at this time, fuel from the fuel supply hole 1a formed in the yoke 2 passes through the fuel passage formed between the bobbin 4 and the yoke 1, and enters the fuel swirler 15. A swirling motion is given by the plurality of swirl grooves formed, and fuel is injected between the ball 6 and the valve seat 14 and through the injection port 13a.

Further, when the current in the coil 3 is cut off, the force of the return spring 12 returns the valve body 5 in the closing direction.

Such reciprocating motion of the valve body 5 when opening and closing the valve is performed while the guide ring 8 is guided by the inner periphery of the guide hole 10 on the core 2 side, and the ball 6 is guided by the inner periphery 15a of the fuel swirler 15. In this way, the valve body 5 reciprocates while being guided at both ends, but when this method is adopted, the overall guide length is shorter than when the valve body is guided only at one end (one side). This has the advantage that the accuracy of the reciprocating operation can be maintained well even in cases where the valve body can be made smaller.

In addition, in the figure, 2a is a relief hole provided on the side surface of the core 2,
Reference numeral 7d denotes relief holes provided in the cylindrical portion 7-1 of the plunger 7, and these relief holes allow the fuel liquid between the inner periphery of the plunger 7 and the guide hole 10 of the core 2 to escape when the valve body 5 reciprocates. This is to prevent compression.

Here, the connection between the plunger of the valve body 5 and the guide ring 8 will be explained.

The reference numeral 78 shown in FIGS. 1 and 5 is a punch mark that was locally pressurized. plastic flow 7 near the pressurizing part 7a.
b is generated, and one end of the outer periphery of the guide ring 8 is pressed from the entire circumferential direction by the self-tightening force of the plastic flow portion 7b. Further, 7c is a taper formed on the inner periphery of the plunger 7, and is in pressure contact with the outer periphery 8a of the end face of the guide ring 8. G is a gap generated when the plunger 7 is locally pressurized, and this gap G is generated between the plastic flow portion 7b and the taper 7c.

The taper 7c receives the outer periphery of one end of the guide ring 8 in a press-contact state, but when the taper 7c receives the outer periphery of the guide ring 8, the force of the plastic flow 7b acts on the lower side of the diagram, this force is transmitted to the guide ring 8, and the outer periphery of the guide ring 8 is pressed against the outer periphery of the guide ring 8. As a result, the outer periphery comes into extremely strong pressure contact with the taper 7c.

Sufficient compressive stress acts from the taper 7c to the pressure-welded portion of the guide ring 8. The compressive stress from this taper 7c acts as a self-tightening force.

As a result, due to the plastic flow part 7b and the taper 7c,
The guide ring 8 is fixedly supported, increasing the bonding strength. In addition, the plastic flow portion 7b is located at the fitting location.
Since the taper 7c can adopt a two-point support structure, the strength against the bending moment caused by the lateral load of the guide ring 8 can be increased.

In order to maintain the self-tensioning force of plastic flow and pressure support of the taper, it is preferable that the members of the Blanjawa and guide ring 8 have the same or similar linear expansion coefficients.

Specifically, in this embodiment, the plunger 7 and the guide ring 8 are made of the same type of stainless steel material.

Further, in order to apply an effective compressive stress from the taper to the outer periphery of the ring end face, the taper angle θ is preferably 60 degrees or less, in other words, the slope angle of the taper θ with respect to the inner periphery of the branjava is preferably 30 degrees or less.

Figures 2 and 3 show that the guide ring 8 (hollow cylindrical body B) and the Blanjawa (hollow cylindrical body) A
It is a combination of

In the connection example shown in Fig. 2, the inner periphery of the branjava is originally straight, and the ring 8 receives the pressing force of the plastic flow 7b.
When the ring 8 is deformed, the ring 8 separates from the inner periphery of the plunger, creating a gap G1. Further, in the coupling example shown in FIG. 3, a stepped portion 7e is provided on the inner periphery of the plunger 8, and in this case as well, a gap G2 similar to that shown in FIG. 2 is generated. Depending on the step portion 7e, the action of the self-tightening force of the taper 7c as in this embodiment cannot be expected.

That is, in the examples shown in FIGS. 2 and 3, the guide ring 8 is restrained and supported at one location (one point), and the ability to withstand lateral loads is weaker than in this embodiment.

FIG. 7 is a measurement diagram showing the displacement when a lateral load P is applied to the guide ring 8 as in this embodiment, where 25 is a chuck, 26 is a holding jig, and 27 is a lateral load applied to the guide ring 8. 28 is a dial gauge, and the dial gauge 28 shows the sum of the displacement due to the lateral load and the deformation of the ring 8.

The measurement example in Figure 7 is the guide ring outer diameter φ4■, inner diameter φ3
．． 2mm, ring length 4.5m, pressure force to produce local plastic flow of 500 to 600kg, and taper slope angle θ/2 to the inner circumference of the plunger between 5 and 10 degrees. FIG. 8 shows the displacement with respect to the lateral load applied to the guide ring 8 at this time.

In FIG. 8, solid lines indicate the combination example of the present invention shown in FIG.
The dotted line shows a conventional connection example using only local plastic flow as shown in Figs. 2 and 3.
While the displacement of the conventional product is 0.12m, the displacement of the inventive product is 0.08m, and the breaking strength of the conventional product is 25kg.
f, whereas the strength of the present invention was as high as 32 kgf.

FIG. 6 shows an example of the work of joining the branjawa and the guide ring 8 of this embodiment.

In Fig. 6, 20 is an upper punch and 21 is a lower punch.

22 is a knockout that is biased by a spring 23.

When connecting, first set the plunger of the valve body 5 between the upper and lower punches 20 and 21, and while fitting the guide ring 8 to the inner periphery of the plunger 7, place one end of the guide ring 8 to the inner periphery of the lower punch 21. insert.

Note that the fitting gap between the bran jaw and the guide ring 8 when set is, for example, 10 μm to 15 μm.

In addition, the guide ring 8 is connected to the knockout 2 via the spring 23.
3 in the axial direction to press the ring end surface 8a against the taper 7c on the inner periphery of the plunger 7. After this process, when the plunger 7 is pressurized with the upper punch 20, the lower punch 2
The annular protrusion 21a provided at 1 is locally embedded in the vicinity of the guide ring fitting portion of the end face of the plunger 7, causing plastic flow in the plunger. As a result, the guide ring 8 is deformed and a gap G is created between the plastic flow part 7b and the taper 7c, but the plastic flow part 7b and the taper 7c strongly tighten the guide ring 8 with their own self-tensioning force (compressive stress). Support restraint.

According to this work process, the work of pressing the guide ring 8 against the taper 7c and punching the branjawa are performed at the same time, so that the work can be streamlined.

According to this embodiment, the coupling between the plunger 7 and the guide ring 8 is strengthened, and the strength against lateral loads is improved. In addition, since the pressing force applied to the plunger 7 is local, the appearance of the plunger 7 does not change after punching, and since the taper 7c acts to center the guide ring 8, good positioning accuracy is achieved. Since there is no need for post-processing to correct the positional accuracy after joining as in conventional press fitting, assembly accuracy can be improved and the production process can be streamlined. Furthermore,
Since clearance can be provided between the guide ring and the plunger during the joining work, the joining work is easy.

Furthermore, in this embodiment, even if the guide ring 8 is fitted halfway into the inner periphery of the plunger, it can be firmly fixed by the plastic flow portion 7b and the taper 7c, so there is an advantage that the relief hole 7d can be easily secured.

〔Effect of the invention〕

As described above, according to the present invention, even when hollow cylindrical bodies are connected using plastic flow caused by local pressurization, one of the hollow cylindrical bodies can be connected to at least one of the plastic flow and taper of the other hollow cylindrical body. Since it is firmly restrained and supported in two places, the strength against lateral loads is improved, and since the taper centers one hollow cylinder, the coaxiality of the hollow cylinders is maintained well, improving assembly accuracy. Can be done.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged sectional view showing one embodiment of the present invention, and FIG.
3 and 3 are partially enlarged sectional views showing other examples of coupling between cylindrical members, FIG. 4 is a vertical sectional view of an electromagnetic fuel injection valve to which an embodiment of the present invention is applied, and FIG. 5 6 is a partial cross-sectional view of the valve body used in the electromagnetic fuel injection valve, FIG. 6 is an explanatory diagram showing one step of the assembly process of the valve body, and FIG. FIG. 8 is a diagram showing the displacement measurement when a load is applied, and shows the displacement when a lateral load is applied to the guide ring of the valve body in comparison with a conventional product. 3... Electromagnetic coil, 4... Fixed core, 5... Valve body, 6... Valve part (ball), 7 (A)... Plunger (hollow cylindrical body), 7a... Machining Pressure part, 7b... Plastic flow part, 7C... Taper, 8(B)... Guide ring (hollow cylindrical part), 8a... Ring end surface, 12... Return spring, 20.21. ··punch. Takafu 2 figure 3 figure 5 --- Ichinakagi 6 --- Wl≧1 (E-le) 1 --- Plunger 8-m-zuidrinf' 1z-11 skin Shibu Umejima-11 bread now

Claims (1)

[Claims] 1. Fit the outer periphery of one end of the other hollow cylindrical body B to the inner periphery of one end of one hollow cylindrical body A to be joined, and The vicinity of the fitting part is locally pressurized to cause plastic flow, and the hollow cylinders A and B are joined together by the self-tightening force around the pressurized part generated by this plastic flow, and the inner circumference of the hollow cylinder A is A method for joining hollow cylindrical bodies, characterized in that a taper is formed in advance in the part, and this tapered surface receives the end face of the hollow cylindrical body B in a pressed state while the hollow cylindrical bodies A and B are in a joined state. . 2. Fitting the outer periphery of one end of the other hollow cylindrical body B to the inner periphery of one end of one metal hollow cylindrical body A to be joined, and forming a taper in advance on a part of the inner periphery of the hollow cylindrical body A. and applying an axial force to the hollow cylinder B during the cylinder fitting process,
The step of pressing one end of the hollow cylinder B against the tapered surface, and punching the end surface of the hollow cylinder A in the vicinity of the cylinder fitting part while pressing the one end of the hollow cylinder B against the tapered surface. A method for joining hollow cylindrical bodies that includes a process of locally applying pressure via a mechanism to generate plastic flow around the pressurized part. 3. The method of joining hollow cylinders according to claim 1 or 2, wherein the hollow cylinders A and B are metal members having the same or similar coefficients of linear expansion. 4. A method for joining hollow cylinders according to any one of claims 1 to 3, wherein the angle of inclination of the taper with respect to the inner periphery of the hollow cylinder A is set to 30 degrees or less. 5. A valve body that performs reciprocating motion to open and close the valve using the attraction force of the electromagnetic coil built into the solenoid valve body and the force of the return spring.
The valve body is an assembly that integrates a valve portion, a hollow cylindrical plunger, a hollow cylindrical guide ring, etc., wherein the outer periphery of one end of the guide ring fits into the inner periphery of one end of the plunger, At this fitting location, the plunger and the guide ring are coupled using plastic flow generated by applying a local pressing force to the end face of the plunger,
The end face of the guide ring on the fitting side is brought into pressure contact with a taper provided on a part of the inner circumference of the plunger, and the valve guide is supported at at least a plurality of locations including the taper and the plastic flow location. Valve body of a solenoid valve.