JPH08135467A - Mounting structure of position sensor - Google Patents

Abstract

PURPOSE: To improve position accuracy without causing deterioration of connection strength by making the ratio of the pad length to the terminal length in the moving direction of a member to be detected smaller than the ratio of the pad length to the terminal length in the direction crossing the detecting direction. CONSTITUTION: When the terminal 50a of a position sensor is fixed on a pad 52 formed in a pattern on a substrate 51 by soldering, the ratio A/a of the longitudinal length A of the pad 52 to the longitudinal length 'a' of the terminal 50a in the moving direction 'x' of the member to be detected is set smaller than the ratio B/b of the transversal length B of the pad 52 and the transversal length 'b' of the terminal 50a in the orthogonal direction to the detecting direction. Thus divergency of the soldering position can be prevented while avoiding deterioration of the soldered strength.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure of a position sensor for detecting a moving position of a member to be detected which moves linearly. The present invention is suitable, for example, when a position sensor that detects the opening degree of a direct-acting piston valve of a carburetor is mounted on a substrate. Therefore, the case of this carburetor will be described below as an example.

[0002]

2. Description of the Related Art For example, an engine of a motorcycle is equipped with an ignition timing control device for detecting an engine speed and a throttle opening and controlling an ignition timing to an ignition timing corresponding to these detected values. There is. When detecting the throttle opening in such ignition timing control, conventionally, in a carburetor equipped with a direct-acting piston valve, the axial movement amount of the piston valve is converted into a rotation angle via a rotation mechanism, and this is converted into a rotation angle. The method of detecting with a potentiometer is generally adopted.

However, in the above-mentioned conventional piston valve type carburetor opening degree detecting device, it is necessary to additionally provide a rotating mechanism for converting the moving amount of the piston valve into a rotating angle, and therefore the structure becomes complicated and the size becomes large. With
There is a problem that the cost increases due to an increase in the number of parts, and there is a problem that the detection accuracy is low due to the structure of converting the linear movement amount of the piston valve into a rotation angle.

Therefore, the applicant of the present invention first examined a detection mechanism capable of directly detecting the axial position of a direct-acting piston valve, provided a magnet on the piston valve, and arranged a magnet for the axial movement of the valve. An opening detection device has been developed in which a plurality of magnetic sensors for extracting changes in magnetic field strength are soldered and connected to a substrate, and the substrate is fixed to a partition wall of the cab body facing the magnet (for example, Japanese Patent Application No. 6- 115251).

According to the opening degree detecting device according to the above development, since the detecting mechanism is composed of the magnet and the magnetic sensor, the structure can be simplified and the size can be reduced as compared with the case where the conventional rotating mechanism is provided. The number of parts can be reduced and the cost can be reduced. Further, since the axial movement position of the piston valve is directly detected, the detection accuracy can be improved as compared with the conventional one in which the axial movement amount is converted into the rotation angle.

[0006]

On the other hand, in order to accurately detect the opening degree of the piston valve, it is necessary to increase the positional accuracy of each magnetic sensor in the moving direction of the valve. Therefore, in the detection device according to the above development, each magnetic sensor is positioned on the substrate so as to have a pitch corresponding to the opening degree, and is fixed by soldering in this state.

By the way, when the magnetic sensor is soldered and fixed on a substrate, cream solder is applied to a pad having a pattern formed on the substrate, and the sensor terminals are placed on the solder application surface and heated in a reflow oven. It is generally welded. In this case, in order to secure the connection strength of the magnetic sensor to the substrate, it is required to set the area of the pad as large as possible.

However, in the above soldering and fixing structure, the magnetic sensor may be displaced due to molten solder during reflow, and as a result, desired pitch accuracy may not be obtained. It is effective to reduce the pad area in order to prevent such misalignment, but this reduces the connection strength.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a mounting structure of a position sensor that can secure position accuracy without causing a decrease in connection strength.

[0010]

SUMMARY OF THE INVENTION The present invention provides a position sensor mounting structure in which a terminal of a position sensor for detecting a moving position of a member to be detected is fixed by soldering on a pad formed on a pattern of a substrate. The ratio A / a between the pad length A and the terminal length a in the moving direction is set smaller than the ratio B / b between the pad length B and the terminal length b in the direction orthogonal to the moving direction. I am trying.

Here, in the present invention, the ratio A / a is changed to the ratio B /
To be smaller than b means that the pad length A in the moving direction is substantially the same as the terminal length a to minimize the amount of solder to the terminal, and the pad length B in the direction perpendicular to the moving direction is the terminal length b. This means that the amount is made larger and the amount of solder for the terminals is made sufficient.

10 and 11 are views for explaining the mounting structure of the present invention more specifically.
11A and 11B are a plan view and a side view, respectively, showing a case where the position sensor is mounted horizontally, and FIG. 11 is a plan view showing a case where the position sensor is mounted vertically. In the figure, 50 is a position sensor, 50a is an external terminal of the sensor, 51 is a substrate,
52 is a pad formed by patterning on the substrate.

In the figure, in the present invention, the ratio A / a of the vertical length A of the pad 52 and the vertical length a of the terminal 50a of the position sensor 50 in the moving direction x of the detected member is a direction orthogonal to the moving direction x. It is configured to be smaller than the ratio B / b of the horizontal length B of the pad 52 and the horizontal length b of the terminal 50a in. That is, the vertical length A of the pad 52 in the direction in which positional accuracy is required is narrowed to be substantially the same as the vertical length a of the terminal 50a, thereby suppressing the amount of solder in the moving direction. Further, the lateral length B of the pad 52, which does not require so much precision, is set to be wider than the lateral length b of the terminal 50a, whereby a sufficient amount of solder is secured.

[0014]

According to the mounting structure of the position sensor according to the present invention, the A / a ratio of the pad length A and the terminal length a in the moving direction of the member to be detected is calculated as the pad length in the direction orthogonal to the detecting direction. Since it is smaller than the B / b ratio of B to the terminal length b, the amount of solder that causes the terminal to float during reflow soldering is minimized in the detection direction of the detected member that requires higher positioning accuracy. So
Positional displacement of the position sensor can be suppressed, and the position accuracy can be improved accordingly. Further, since the pad length is increased and the amount of solder is increased in the orthogonal direction where accuracy is not required so much, sufficient soldering strength can be secured.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to 9 are views for explaining a mounting structure of a position sensor according to an embodiment of the present invention.
1 is a side view of a carburetor to which the structure of this embodiment is applied, FIG. 2 is a sectional view taken along line II-II of FIG. 1, FIG. 3 is a sectional view showing a detection main part of an opening degree detection device, and FIG. IV-IV line sectional view, FIG. 5 is a plan view showing a main part of detection of the apparatus of the above-mentioned embodiment, FIG. 6 is a plan view showing a sensor unit to which the structure of the above-mentioned embodiment is applied, FIG. 7 is a side view of the sensor unit, FIG. 8 is a plan view of the magnetic sensor,
FIG. 9 is a circuit diagram of the magnetic sensor. In this embodiment, a case where the invention is applied to an opening degree detection device for a carburetor having a direct-acting piston valve will be described as an example.

In the figure, reference numeral 1 is a VM type carburetor to which the apparatus of this embodiment is applied. A float chamber 3 is bolted to an opening on the lower surface of a cab body 2 of the carburetor. Is provided with a wax type auto choke mechanism 4 that opens and closes a starter passage 6a that bypasses the venturi passage 6. A float 5 is vertically swingably arranged in the float chamber 3. The float 5 moves up and down in accordance with the change in the liquid level of the fuel in the chamber 3 to open and close a fuel introduction port (not shown), thereby keeping the liquid level of the fuel in the float chamber 3 constant.

The cab body 2 is made of zinc die-cast, and has a cylindrical main body portion 2a having a venturi passage 6 through which intake air (see mark a in FIG. 1) flows.
Cylinder portion 2b having a valve chamber 7 extending vertically upward from the main body portion 2a and opening into the venturi passage 6
And the body portion 2 so as to be coaxial with the cylinder portion 2b.
Fuel introduction part 2 extending from a into the float chamber 3
and c are integrally formed.

A lid 8 is attached to the upper end opening of the cylinder portion 2b, and a bottomed cylindrical piston valve 9 is axially slidably inserted into the valve chamber 7 of the cylinder portion 2b. There is. The piston valve 9 is made of brass or aluminum alloy, and a pressing plate 11 is inserted in the piston valve 9, and the valve 9 is biased in the closing direction between the pressing plate 11 and the lid 8. A spring 10 is provided.

Further, the pressing plate 11 has a piston valve 9
E-ring 2 for vertical positioning of the jet needle 21 inserted into the above-mentioned fuel introduction portion 2c through the bottom portion 9b of the
1a is pressed and fixed to the bottom of the piston valve 9.

One end of a throttle cable 16 is locked to the bottom portion 9b of the piston valve 9, and the extension end of the cable 16 is connected to the lid 8 by a guide pipe 17
It is connected to an accelerator grip (not shown) through the inside. By operating the accelerator grip, the piston valve 9 is moved in the vertical direction to change the passage area of the venturi passage 6 between fully closed and fully opened. In addition, 9d is a slit for inserting the throttle cable 16 in the piston valve 9 in a state of being locked to the bottom portion 9b.

A needle jet 20a is inserted in the upper portion of the fuel introduction portion 2c, and it opens below the piston valve 9 in the venturi passage 6.
Further, the main jet 20 is provided at the lower end of the fuel introducing section 2c.
b is screwed in and opens into the fuel. Within the needle jet 20a, the jet needle 2
1 is inserted so that the piston valve 9 can be moved forward and backward.
As the jet needle 21 moves up and down, the effective opening area of the upper end opening of the needle jet 20a is changed, whereby the amount of fuel sucked into the venturi passage 6 is adjusted.

A throttle screw 18 for adjusting the idling speed is screwed into a portion of the main body portion 2a which faces the lower end portion of the piston valve 9, and the venturi passage 6 is lubricated in the upper portion thereof. An oil supply port 19 for supplying oil is connected and formed. The lubricating oil supplied from the oil supply port 19 flows down through the groove 9a formed on the side surface of the piston valve 9 and is supplied to the venturi passage 6. Further, an air vent passage 15 is formed in the cab body 2 to connect the space above the float chamber 3 and the outside (see FIG. 1), and the air vent passage 15 keeps the inside of the float chamber 3 at atmospheric pressure. It has become.

When viewed in the piston valve moving direction, the detection main part of the opening degree detecting device of this embodiment is orthogonal to the intake flow a flowing in the venturi passage 6 as shown in FIG. It is arranged on a straight line b passing through the center of the valve 9. The detection main part is a permanent magnet 25 located at the upper edge of the piston valve 9, and two magnetic sensors 28a, 28 fixed to the outer surface of the partition wall 2d of the cylinder part 2b.
b and.

The outer end surface of the permanent magnet 25 is located slightly inside the outer peripheral surface of the piston valve 9, so that there is a slight gap with respect to the inner surface of the partition wall 2d of the cylinder portion 2b. Furthermore, the inner end surface of the permanent magnet 25 projects slightly inward from the inner peripheral surface of the piston valve 9.

The permanent magnet 25 is formed by insert molding directly on the side wall of the piston valve 9 and integrally connected, and is magnetized after this molding. The magnetizing direction is the same as the moving direction of the piston valve 9. Further, the magnetic sensors 28a, 28b of the permanent magnet 25 are also provided.
A convex pointed portion 25a is formed on the outer end surface facing to (see FIG. 3), and the pointed portion 25a is pointed in the direction perpendicular to the moving direction of the piston valve 9 and in the vertical direction of the permanent magnet 25. It is located approximately in the center. By making the magnetic flux density distribution steep by this, the magnetic sensors 28a, 28
The hysteresis width of the detection sensitivity of b can be reduced, and the detection accuracy can be improved.

On the outer surface of the partition wall 2d of the cylinder portion 2b, a sensor chamber 30 that opens to the side is integrally formed, and a sensor unit 26 is accommodated in the sensor chamber 30. A resin sealing layer 35 is formed in the sensor chamber 30, and a potting agent made of a room temperature curing epoxy resin or heat conductive silicon is injected and filled in the sensor chamber 30 and dried and solidified. The sensor unit 26 is resin-sealed.

The sensor unit 26 is constructed by soldering and fixing the two magnetic sensors 28a and 28b on the inner surface of the substrate 27 made of glass epoxy resin or the like, which is located on the partition wall 2d side. As shown in FIG. 4, the base plate 27 has a positioning pin 31 in the sensor chamber 30, and a part of the base plate 27 protrudes into the sensor chamber 30 so that the metal pin 3 is press-fitted.
2 is inserted into each positioning hole 27a of the base plate 27, and a push nut 33 is fitted to the metal pin 32 so that the metal pin 32 is positioned and fixed on the partition wall 2d in the sensor chamber 30.

Each of the magnetic sensors 28a and 28b accommodates a detection element composed of an alternating Hall IC or the like and an amplifier circuit board in a package, and a grounding ground terminal 40a and input / output terminals 40b and 40c from the package. The sensor S of the sensor is configured to project, and is offset from the center C of the package to the ground terminal 40a side (see FIG. 8).

On the substrate 27, each magnetic sensor 28a,
Pad 41 to which terminals 40a-40c of 28b are connected,
And a land 42 to which the external lead wire 29 is connected is formed in a pattern, and the pad 41 and the land 42 are connected to each other via a circuit wiring (not shown). For these circuit wirings, a copper foil film is formed on the surface of the substrate 27 by plating or the like, and the pads 41 and the lands 4 are formed on the copper foil film.
2. A photoresist film is formed according to the wiring pattern, and is then subjected to etching treatment. The terminals 40a to 40c and the lead wires 29 are formed by applying cream solder to the pads 41 and the lands 42,
It is connected by reflow soldering by heating it in a reflow furnace.

Further, as shown in FIG. 8, the vertical length A of the pad 41 in the moving direction x of the piston valve 9 and by extension of the permanent magnet 25 is the same as the vertical length a of each of the terminals 40a to 40c, or slightly longer than a. It is set large. Further, each pad 4 in the direction perpendicular to the moving direction x
The horizontal length B of 1 is set larger than the horizontal length b of each of the terminals 40a to 40c. As a result, the ratio A / a of the lengths of the pads and terminals in the moving direction is smaller than the ratio B / b in the direction of right angle, whereby the amount of solder in the moving direction is smaller than the terminal size, and In the direction, the amount of solder is larger than the terminal size.

Further, each magnetic sensor 28 on the substrate 27 is
A PTC thermistor 43 showing a positive temperature characteristic is disposed as a heating element near a and 28b. The temperature near the magnetic sensors 28a and 28b is kept at 0 to 60 ° C. by the thermistor 43, thereby avoiding a decrease in detection sensitivity due to a change in ambient temperature. In addition,
The PTC thermistor 43 is a magnetic sensor 28 on the substrate 27.
It may be disposed on the side opposite to a and 28b, or another heating element may be used.

The detecting portion S of each of the magnetic sensors 28a and 28b is arranged on a straight line parallel to the moving direction x of the permanent magnet 25, as shown in FIGS. in this case,
In the upper magnetic sensor 28b, the offset side of the detection unit S of the upper magnetic sensor 28b is the moving direction x and the lower magnetic sensor 28a.
It is arranged to face to the side. Further, the lower magnetic sensor 28a is arranged such that the offset side of the detection unit S thereof is oriented in the direction orthogonal to the moving direction x. By arranging in this way, the pitch of the detection units S can be narrowed compared to the case where the sensors are oriented in the same direction. The positions of the two magnetic sensors 28a and 28b are the permanent magnets 2 when the throttle opening is the first opening slightly opened from the idling opening and the second opening further opened from this.
5 is set to face the detection unit S of each sensor.

Here, the permanent magnet 25 and the magnetic sensors 28a and 28b are arranged on the straight line b which is orthogonal to the axis of the venturi passage 6, that is, the flow direction a of the intake air and which passes through the center of the piston valve 9 as described above. It is located in. As a result, the vibration of the piston valve 9 causes the permanent magnet 25 to move.
The change in the gap between the magnetic sensors 28a and 28b is avoided. That is, the piston valve 9 easily vibrates in the flow direction of intake air due to the influence of intake pulsation. Therefore, when the permanent magnet 25 and the magnetic sensors 28a, 28b are arranged on the axis of the venturi passage 6, that is, so as to face each other in the vibration direction, the gap between the two 25, 28a, 28b may change. The result detection accuracy may be reduced.

In addition, the piston valve axial mounting position of the base plate 27 is such that the permanent magnet 25 faces the lower magnetic sensor 28a when the piston valve 9 reaches the first opening slightly raised from the idling position. To adjust. This is because in the state where the opening degree of the piston valve 9 is small, the intake amount largely changes due to a slight change in the opening degree of the piston valve 9, but does not change so much when the opening degree increases. Therefore, it is necessary to detect the small opening position of the piston valve 9 with higher accuracy, and by prioritizing the opposing of the permanent magnet 25 and the magnetic sensor 28a, the detection accuracy of the small opening position can be improved.

Further, each lead wire 29 is connected to a throttle opening discriminating circuit (not shown). This determination circuit is used for the permanent magnet 2 accompanying the axial movement of the piston valve 9.
When the magnetic field strength of No. 5 is equal to or higher than a predetermined threshold value, it is determined that the axial position of the permanent magnet 25 matches any one of the magnetic sensors 28a and 28b, and the throttle opening is determined accordingly. ing.

Next, the function and effect of this embodiment will be described. According to the opening degree detection device of the present embodiment, when the piston valve 9 rises from the idling position to the slightly opened first opening degree, the permanent magnet 25 faces the lower magnetic sensor 28a, and from the magnetic sensor 28a. Output exceeds the predetermined threshold value, whereby the throttle opening is determined to be the first opening. When the piston valve 9 further rises to the second opening, the permanent magnet 25 faces the upper magnetic sensor 28b, and the output from the magnetic sensor 28b exceeds the threshold value, whereby the throttle opening becomes the second opening.
The opening is determined.

In this embodiment which operates in this manner, when soldering and fixing the magnetic sensors 28a and 28b on the substrate 27, the ratio A of the pad length A to the terminal length a in the moving direction x of the permanent magnet 25 is A. Since / a is made smaller than the ratio B / w of the pad length B and the terminal length b in the direction orthogonal to the moving direction x, the pad length A in the moving direction x is substantially the same as the terminal length a. Therefore, the amount of solder is smaller than the terminal size, and therefore, the magnetic sensors 28a and 28b can be prevented from being displaced in the movement direction x during reflow soldering, and the positional accuracy can be improved. Further, since the pad length B is set to be larger than the terminal length b in the orthogonal direction where positional accuracy is not so required, a sufficient amount of solder can be secured and a sufficient soldering strength can be secured.

In the above embodiment, the case where the present invention is applied to a carburetor having a direct acting piston valve has been described as an example, but the application of the present invention is not limited to this, and a position requiring positional accuracy is used. It can be applied to any case where the sensor is mounted on the board by soldering.

[0039]

As described above, according to the mounting structure of the position sensor of the present invention, the ratio of the pad length to the terminal length in the moving direction of the member to be detected is defined as the pad length to the terminal in the direction orthogonal to the detecting direction. Since it is made smaller than the ratio with respect to the length, there is an effect that it is possible to prevent positional deviation during soldering while avoiding a decrease in soldering strength and improve the positional accuracy.

[Brief description of drawings]

FIG. 1 is a side view showing a carburetor opening detection device to which a position sensor mounting structure according to an embodiment of the present invention is applied.

FIG. 2 is a cross-sectional view of the apparatus of the above embodiment.

FIG. 3 is a cross-sectional view showing a main part of detection of the apparatus of the above embodiment.

FIG. 4 is a cross-sectional view showing a fixed portion of a substrate of the apparatus of the above embodiment.

FIG. 5 is a plan view showing a main part of detection of the apparatus according to the embodiment.

FIG. 6 is a plan view showing a substrate having the above-mentioned embodiment structure.

FIG. 7 is a side view of the substrate having the above-described embodiment structure.

FIG. 8 is a plan view showing a magnetic sensor having the above-described embodiment structure.

FIG. 9 is a circuit diagram of the apparatus of the above embodiment.

FIG. 10 is a diagram for explaining the configuration of the present invention.

FIG. 11 is a diagram for explaining the configuration of the present invention.

[Explanation of symbols]

27,51 substrate 28a-28c, 50 magnetic sensor (position sensor) 40a-40c, 50a terminal 41,52 pad x moving direction of detected member A pad length in moving direction B pad length in orthogonal direction a moving direction Terminal length b Terminal length in orthogonal direction

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G01B 7/30 B // F02D 9/00 A

Claims (1)

[Claims] 1. In a mounting structure of a position sensor, wherein a terminal of a position sensor for detecting a moving position of a member to be detected is fixed by soldering on a pad formed on a substrate by patterning, a pad length A in the moving direction is set. The position sensor mounting structure is characterized in that the ratio A / a between the terminal length a and the terminal length a is smaller than the ratio B / b between the pad length B and the terminal length b in the direction orthogonal to the moving direction.