JP2641878B2 - How to fix the diaphragm - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for holding and fixing a diaphragm between two resin members.

<Conventional technology> A venturi area is variably controlled by a sliding throttle valve connected to a diaphragm forming a negative pressure chamber, and the negative pressure chamber is selectively communicated with the atmosphere and a negative pressure downstream of the sliding throttle valve. A carburetor using a sliding throttle valve that controls the pressure in the negative pressure chamber by operating a switching valve that operates is described in, for example, Japanese Patent Publication No.
No. 00 or JP-B-58-48965. In the manufacture of these vaporizers, caulking and bonding are generally performed to fix the diaphragm, but depending on the conventional method, all of the workability, mechanical strength and sealing characteristics must be satisfied. Was difficult.

<Problems to be Solved by the Invention> In view of the problems of the related art, a main object of the present invention is to provide a method for fixing a diaphragm that can satisfy all of workability, mechanical strength, and sealing performance. To provide.

<Means for Solving the Problems> According to the present invention, such an object is provided at an inner peripheral edge of a center hole of a diaphragm between two resin members to which an axially movable member is mounted at the center thereof. A method of fixing a diaphragm in which said two resin members are welded to each other by using an ultrasonic horn after sandwiching the obtained bead. An annular body having a central depression is formed to form a surface at one end surface in the axial direction, and a soft elastic member is disposed in the central depression, and the resin member holding the bead, This is attained by providing a method for fixing a diaphragm, wherein the ultrasonic horn is pressed against the annular surface so as to be positioned inside a bead.

<Operation> In this manner, by positioning the annular surface of the ultrasonic horn inside the inner diameter of the bead of the diaphragm,
It is possible to eliminate the possibility that the diaphragm is welded to any one of the two resin members, even if locally. In addition, by disposing a soft elastic member in the central depression of the ultrasonic horn, a movable member attached to the center of the resin member such as a switching valve is moved by this, and the movable member is moved to the resin member. Welding can be avoided.

<Embodiment> Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a sliding throttle valve type carburetor to which the present invention is applied. This carburetor has a carburetor body 1 defining an intake passage 2 extending in the left-right direction, and a carburetor cover 3 closing an upper end opening thereof. A generally cylindrical sliding throttle valve 4 is supported at an intermediate portion of the intake passage 2 so as to be able to protrude and retract, and a jet needle 5 protruding from the tip of the throttle valve 4 projects into the needle jet 6. The two parts cooperate with each other to supply an appropriate amount of fuel into the intake passage 2 according to the flow rate of intake air flowing through the variable venturi formed by the sliding throttle valve 4.

The sliding throttle valve 4 is slidably supported in the axial direction by a sleeve 7 provided in the body so as to be orthogonal to the intake path 2, and has a suction side on its downstream side. A hole 8 for introducing a negative pressure is provided, and an intake negative pressure is always introduced into a first valve chamber 9 formed inside the sliding throttle valve 4. At the base end of the sliding throttle valve 4, a switching valve holder 10 is provided.
The slide throttle valve 4 is retained by a convex portion 16 provided on the inner periphery thereof. Also, an O-ring 16 is provided between these two parts.
a is provided to ensure airtightness of the first valve chamber 9.
A compression coil spring 15 is interposed between the lower end of the switching valve holder 10 and the enlarged diameter head 5a of the jet needle 5, and this compression coil spring resiliently holds the jet needle 5 at a predetermined position. ing. At the upper end of the switching valve holder 10, a holding member
11 is fitted, from the hole 25 provided in the center,
The upper end 24 of the valve element 14 received in the switching holder 10 protrudes. Also, between the holding member 11 and the switching valve holding body 10,
A bead 12a on the inner peripheral edge of the diaphragm 12 is clamped, while a bead on the outer peripheral edge of the diaphragm 12 is clamped between the body 1 and the cover 3.

Thus, a negative pressure chamber 3a is defined between the diaphragm 12 and the cover 3, and an atmosphere chamber 1a communicating with the atmosphere via the passage 1b is defined between the body 1 and the diaphragm 12. . An arm 24 that tilts in conjunction with the throttle grip of a motorcycle is provided on the upper end 24 of the valve body 14.
Thirteen free ends are in contact. 2, the valve element 14 has a flange 20 at the center thereof, and is sandwiched between the flange and the upward shoulder 10a of the inner periphery of the switching holder 10. It is constantly urged upward by a conical compression coil spring 21.

The second valve chamber 26 formed inside the switching valve holder 10 includes:
Negative pressure chamber 3a is always provided through communication passage 27 provided in holding member 11.
Is in communication with When the valve element 14 is at the upper position shown in FIG. 2, the lower end of the valve element 14 is
The second valve chamber 26 is guided by the axial rib 19 provided on the inner peripheral surface of the bottom of the switching valve holder.
It also communicates with the first valve chamber 9 via an axial passage 17 provided at the lower end of 10. However, when the valve element 14 is pushed down by the lever 13 against the spring force of the compression coil spring 21, a conical portion 18 provided at the lower end of the valve element 14 is provided at the open end of the passage 17. The communication with the passage 17 is cut off by cooperating with the valve seat 17a. Further, a conical valve seat is provided at the inner open end of the center hole 25 of the holding member 11.
23 is formed, and the valve seat has a flange 20
The conical portion 22 provided adjacent to the
Close contact with 21 forces. The conical surface forming the valve seat 23 is provided with open ends of passages 29 and 30 formed in the lateral direction through the switching valve holder 10 and the holding member 11. Therefore, when the valve element 14 is in the upper position shown in the figure, the conical portion 22 closes the open end of the passage 30, but when the upper end 24 of the valve element 14 is pushed down as described above, The second valve chamber 26 communicates with the atmosphere chamber 1a via the passages 29 and 30. An end of the communication passage 27 on the side of the second valve chamber 26 is opened by a cutout 28 provided in the valve seat 23.

 Next, the operation of this embodiment will be described.

As shown in FIG. 1, when the valve body 14 is pushed down to a lower position by the arm 13 against the spring force of the compression coil spring 21, the passages 29 and 30 and the second valve chamber 26 And passage 27
, The negative pressure chamber 3a and the atmosphere chamber 1a communicate with each other, so that the sliding throttle valve 4 does not receive any upward force, and is held at the illustrated Venturi fully closed position. Next, the arm
When the valve body 14 rises due to the spring force of the compression coil spring 21, the conical portion 22 of the valve body 14 abuts the valve seat 23 to shut off the passage 30 and the lower end of the valve body 14. Is separated from the valve seat 17a, the intake negative pressure on the downstream side of the throttle valve 4 is reduced through the passage 27, the second valve chamber 26, the passage 17, the first valve chamber 9 and the hole 8. The sliding throttle valve 4 is introduced into the negative pressure chamber 3a and is driven upward by the action of the diaphragm 12. The upward movement is such that the upper end 24 of the valve body 14 is pushed down by the arm 13, the conical portion 22 separates from the valve seat 23 against the spring force of the spring 21, and the atmosphere is introduced into the negative pressure chamber 3 a. Continue until you do.

Thus, the sliding throttle valve 4 moves up and down according to the tilt position of the arm 13. In this case, the movement of the main body 14 of the switching valve is performed lightly without relatively resistance, and the passage through which the intake air and the atmosphere flow is linear, short, and simple. You will exercise well.

Next, the procedure for clamping the bead 12a on the inner peripheral edge of the diaphragm 12 between the switching valve holder 10 and the clamping member 11 will be described.

As shown in FIG. 3 and FIG. 4, the holding member 11 and the switching valve holder 10 are cylindrical inner and outer peripheral surfaces 32, 33.
Are in sliding contact with each other through
Annular tapered surfaces 34 and 39 formed above and below 30 are provided on the valve holder 10 side, respectively, and are welded to annular corners 35 and 40. As described above, since the inner and outer peripheral surfaces 32 and 33 are welded over a relatively wide axial length, it is possible to sufficiently secure the strength of connection between the two members in the falling direction. In this case, the required sealing characteristics are ensured by the welded connection formed at the abutting portion between the tapered surfaces 34, 39 and the corners 35, 40. Further, the outer peripheral surface of the holding member 11 where the passage 30 is opened
At 36, axial ribs 38 are protruded at regular intervals, and the ridges of these ribs 38 correspond to the corresponding switching valve holders 10.
Because it is in contact with the inner peripheral surface 37 of Leakage of air along the circumferential direction between both surfaces can be suppressed.

On the other hand, in order to realize such welding, as shown by the imaginary line in FIG.
The ultrasonic horn 50 having an annular end face formed by providing the same is used. In this welding process, first, the compression coil spring 21 and the valve element 14 are set in the switching valve holder 10, and the bead 12a of the diaphragm 12 is placed on the upper surface of the switching valve holder 10. Further, the holding member 11 is positioned by a jig or the like so that the center position of the switching valve holding member 10 does not deviate from each other, and the outlet of the hole 25 is placed so that the center hole of the holding member 11 does not contact the valve body 14. Slightly enlarged part 25a at the end
A metal ring 53 as shown by an imaginary line is mounted between the valve body 14 and the outer periphery of the upper end 24 of the valve body 14. In this state, the horn 50 is concentrically mounted on the upper surface of the holding member 11.
Press.

Then, the holding members 11 descend while the mutually contacting surfaces of the cylindrical inner and outer peripheral surfaces 32 and 33 melt, and the annular tapered surface.
It descends until 34 and 39 contact the annular corners 35 and 40 of the switching valve holder 10. This descending height is set from the interference of the diaphragm 12.

Here, the outer diameter of the ultrasonic horn 50 is
It is set smaller than the inner diameter of the center hole surrounded by the twelve beads 12a. By doing so, it is possible to prevent the portion near the bead 12a from being welded to the holding member 11 and the switching valve holder 10 to prevent the diaphragm 12 from being pulled or the flexibility of the diaphragm 12 from being impaired. .

Further, a soft elastic resin material 52 such as a urethane foam material is provided in a central depression 51 on the end face of the horn 50. As a result, the valve element 14 is pushed downward, and the tapered portion 22 of the valve element 14 is kept in non-contact with the valve seat 23 of the holding member 11, so that even the same portion is prevented from being welded. Further, since the center position of the valve body 14 is accurately held by the metal ring 53, it is possible to make every effort to prevent welding.

In the above embodiment, the corners 35, 40 provided on the switching valve holder 10 side are brought into contact with and welded to the annular tapered surfaces 34, 39 provided on the holding member 11 side. Thus, a welded portion having excellent sealing properties is formed, but a tapered surface may be provided on the side of the switching valve holder, and a corresponding corner may be provided on the side of the holding member 11. Further, instead of using a tapered surface, an end surface or a shoulder surface facing the axial direction may be abutted against each other to form a welded portion in the same portion.

<Effects of the Invention> In this way, a diaphragm fixing method that enables good workability, high bonding strength, and excellent sealing performance is provided, and a great effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a sliding throttle valve carburetor to which the present invention is applied, with a part thereof being omitted. FIG. 2 is an enlarged longitudinal sectional view showing a main part of FIG. FIG. 3 is an enlarged bottom view of the holding member shown in FIG. 1 and FIG. FIG. 4 is an enlarged sectional view taken along line IV-IV of FIG. 10: switching valve holder, 11: clamping member 12: diaphragm, 12a: bead 50: ultrasonic horn, 51: central hollow 52: elastic resin material, 53: ring

Claims (1)

(57) [Claims] 1. A bead provided at the inner peripheral edge of a center hole of a diaphragm is sandwiched between two resin members to which an axially movable member is mounted at the center thereof, and the ultrasonic horn is used. A method of fixing a diaphragm that welds two resin members, wherein the ultrasonic horn has an annular body having a central recess to form an annular surface having an outer diameter smaller than the inner diameter of the bead at one axial end surface. A soft elastic member is disposed in the central depression, and the ultrasonic horn is arranged on the resin member holding the bead so that the annular surface is located inside the bead. And fixing the diaphragm.