JP3387372B2 - Flow sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor for detecting the flow rate of fluid passing through a flow path.

[0002]

2. Description of the Related Art A flow rate sensor of a type which detects a flow rate from a thermal equilibrium state of a bridge including an element such as a heat sensitive resistor disposed in a fluid such as gas or liquid is disclosed in, for example, Japanese Patent Laid-Open No. 4-29.
It is known from Japanese Patent No. 1117. 7 and 8 are configuration diagrams showing a configuration of a conventional device of a heat-sensitive flow sensor for measuring an intake air amount of an engine. FIG. 7 is a partial cross-sectional perspective view of the conventional device, and FIG. It is sectional drawing seen from the inflow direction. In the figure, 100 is a housing that forms a flow path of intake air flowing in the direction of arrow A, 101 is a measurement pipe line for measuring the intake air amount, and 102 is a resistance value change due to heat taken by the intake air. Heat sensitive resistor, 10
3 is a temperature compensating resistor for measuring the temperature of the intake air, 104 is a hollow supporting member for supporting the measuring conduit 101 inside the housing, and a holder 105 for holding the heat sensitive resistor 102 is housed in the hollow portion. There is. Reference numeral 106 denotes an adhesive, and the holder 105 is made of the adhesive 106 to support the supporting member 104.
Permanently attached to. 107 is a control circuit for controlling the thermal resistor 102, and 108 is the support member 104 and the holder 10.
The sealing material that fills the gap between the control circuit 107 and the control circuit 107 ensures the airtightness of the space.

[0003]

In the conventional flow rate sensor, the holder 105 is housed inside the supporting member 104, so that the outer shape of the supporting member 104 becomes large and the ventilation resistance of the intake air becomes large.

Further, an adhesive 106 is required to fix the holder 105, and since this adhesive 106 is made of a thermosetting resin, it takes a long curing time to make it difficult to improve productivity.

The present invention solves the above problems and provides a flow rate sensor capable of reducing the flow resistance of a fluid and improving productivity.

The present invention also provides a flow sensor which is easy to assemble.

The present invention also provides a flow rate sensor capable of reducing the drift of the fluid.

Further, the present invention provides a flow rate sensor capable of improving the productivity as well as the measurement accuracy.

[0009]

[0010]

A flow rate sensor according to the present invention includes a housing forming a flow path through which a fluid passes, a measuring pipe for measuring a flow rate passing through the housing, and the measuring pipe. A support member for supporting the inside of the housing and a flow rate measuring means for measuring the flow rate at one end are held, and the one end is press-fitted into an insertion hole provided in the measurement conduit and the other end is fixed to the housing. And a fitting member provided on at least one of the insertion hole and one end of the holder member, and the supporting member is a fluid flow member.
The cross-sectional area in the insertion direction is approximately equal to the cross-sectional area of the holder member
Or less, and the supporting member and the holder part
The material divides the cross-sectional area of the flow channel into substantially equal parts .

Further, in the flow rate sensor according to the present invention, the fitting member is a convex portion.

[0012]

Further, the flow rate sensor according to the present invention has a guide member for defining the installation angle of the holder member with respect to the inflow direction of the fluid.

[0014]

[0015]

DETAILED DESCRIPTION OF THE INVENTION

Embodiment 1. 1 and 2 are configuration diagrams showing the first embodiment, FIG. 1 is a cross-sectional view orthogonal to the fluid flow direction, and FIG. 2 is a cross-sectional view parallel to the fluid flow direction. In the figure, 1 is a substantially cylindrical housing that forms a flow path through which intake air as a fluid passes, and 2 is a substantially horn that is formed so that its cross-sectional shape when viewed from the flow direction of the intake air is concentric with the housing 1. The measuring pipe line 3 is formed of thin film platinum or the like, and is a heat-sensitive resistor as a flow rate measuring means whose resistance value changes when heat is taken by the intake air. The measuring pipe line 3 projects in the direction of the center of the measuring pipe line 2. . Reference numeral 4 is a temperature compensating resistor for measuring the intake air temperature in order to correct the measurement result by the heat sensitive resistor 3 with the intake air temperature.

Reference numeral 5 denotes a holder as a holder member for holding the thermosensitive resistor 3 with a predetermined positional relationship at the end of one end, and one end is press-fitted into an insertion hole formed in the measurement conduit 2 and the other. The ends are fixed to the housing 1. Reference numeral 6 denotes a support member that supports the measurement conduit 2 inside the housing, and has a flat plate shape whose cross-sectional shape in the flow direction is substantially streamlined so as not to hinder the flow of air. In order to clarify the holder 5 and the support member 6 in FIG.
Is shaded. As shown by the broken line in FIG. 1, the cross-sectional area of the support member 6 is equivalent to or is within the projected cross-sectional area of the holder 5 in the flow direction. That is,
Since the support member 6 does not include the holder 5, the cross-sectional area of the support member 6 can be minimized, and the flow resistance of intake air can be reduced. Further, the holder 5 and the support member 6 are arranged so as to divide the cross-sectional area of the flow channel into substantially equal parts, and in FIG. 1, the cross-sectional area of the flow channel is divided into two substantially equal areas.

Reference numeral 7 is a control circuit for controlling the thermal resistor 3 to measure the intake air flow rate, 8 is a case for accommodating the control circuit 7, and 9 is a seal filled in the gap between the holder 5 and the case 8. The material ensures the airtightness of the control circuit 8 and permanently fixes the holder 5.

Therefore, according to the first embodiment, the support member 6
Since it is not necessary to incorporate the holder 5, it is possible to reduce the cross-sectional area of the intake air in the flow direction and reduce the flow resistance. Moreover, since it is not necessary to incorporate the holder 5, the degree of freedom in designing the support member 6 can be improved.

Further, since the support member 6 is arranged to be equivalent to or within the projected cross-sectional area of the holder 5 with respect to the flow direction, the flow resistance of the intake air can be reduced.

Further, since the holder 5 and the supporting member 6 are arranged so as to divide the cross-sectional area of the flow passage into substantially equal parts, it is possible to reduce the drift of the intake air.

3 and 4 are enlarged cross-sectional views of the essential parts of the first embodiment, and FIG. 3 is a cross-sectional view parallel to the fluid flow direction,
FIG. 4 is a plan sectional view of FIG. In the figure, 10 is an insertion hole provided in the measurement conduit 2, and 11 is a convex portion as a fitting member extending so as to face each other along the inner wall of the insertion hole 10. The facing distance of the convex portion 11 is the holder. 5 is slightly smaller than the outer dimensions. Reference numeral 12 is a guide as a guide member extending along the inner wall of the insertion hole 10.
The holder 5 is provided so as to be arranged at a predetermined angle with respect to the intake air flowing in from the direction of the arrow A, and as a result, the thermal resistor 3 is provided with respect to the intake air. It is arranged with a predetermined angle.

FIGS. 5 and 6 are enlarged views of the essential parts of the first embodiment, which correspond to FIGS. 3 and 4, respectively. In the figure, the holder 5 has its angle defined by the guide 13 with respect to the flow direction of the intake air, and is pressed into the insertion hole 10 while crushing the protrusion 11. In other words, the angle at which the holder 5 is assembled is defined by the guide 12, so that the angle of the heat-sensitive resistor 3 with respect to the flow direction of the intake air is defined.

Therefore, according to the first embodiment, it is possible to prevent variations in the assembly angle when the holder 5 is inserted, and it is possible to improve the flow rate measurement accuracy.

Further, since it is assembled by press fitting, no adhesive is required, and the step of thermosetting is also unnecessary. Further, since the assembly is performed by press fitting, the measurement pipe line 2 and the holder 5 are firmly engaged with each other, and sufficient vibration resistance and impact resistance can be obtained.

Further, since the convex portion 11 is adopted as the fitting member, the convex portion is crushed at the time of press-fitting so that it can be easily press-fitted.

Although the convex portion 11 is provided on the insertion hole 10 side in the first embodiment, it may be provided on the holder 5 side.

In the first embodiment, the support member 6 supports the measuring conduit 2 in the housing 1, but the holder 5
Alternatively, a supporting function may be added so that the holder 5 and the supporting member 6 support the measuring conduit 2.

The above embodiment is merely one embodiment of the present invention, and various embodiments can be taken within the scope of the spirit of the present invention.

[0029]

As described above, according to the flow rate sensor of the present invention, the flow resistance of the fluid can be reduced and the productivity can be improved.

Further, according to the flow rate sensor of the present invention, it is easy to assemble and the productivity can be improved.

Further, according to the flow rate sensor of the present invention, the drift of the fluid can be reduced and the measurement accuracy can be improved.

Further, according to the flow rate sensor of the present invention, it is possible to improve productivity and measurement accuracy.

[0033]

[Brief description of drawings]

FIG. 1 is a cross-sectional view orthogonal to a fluid flow direction.

FIG. 2 is a cross-sectional view parallel to a fluid flow direction.

FIG. 3 is an enlarged cross-sectional view of an essential part parallel to the fluid flow direction.

FIG. 4 is a plan sectional view of FIG.

FIG. 5 is an enlarged assembly view of a main part of the first embodiment.

FIG. 6 is an enlarged assembly view of a main part of the first embodiment.

FIG. 7 is a partial cross-sectional perspective view of a conventional device.

FIG. 8 is a cross-sectional view orthogonal to the fluid flow direction of the conventional device.

[Explanation of symbols]

1 housing, 2 measuring lines, 3 heat sensitive resistors, 4
Temperature compensation resistor, 5 holder, 6 supporting member, 7 control circuit, 8 case, 9 sealing material, 10 insertion hole, 11
Convex part, 12 guide, 100 housing, 101
Measuring pipe line, 102 heat sensitive resistor, 103 temperature compensation resistor, 104 supporting member, 105 holder, 106 adhesive, 107 control circuit, 108 sealing material

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01F 1/00-9/02

Claims (3)

(57) [Claims] 1. A housing forming a flow passage through which a fluid passes, a measuring pipe for measuring a flow rate passing through the housing, a support member for supporting the measuring pipe in the housing, and one end portion. A holder member that holds flow rate measuring means for measuring the flow rate, and has one end press-fitted into an insertion hole provided in the measurement conduit and the other end fixed to the housing; A hole or a fitting member provided on at least one of the one ends of the holder member, and the supporting member has a cross-sectional area with respect to a fluid inflow direction.
Is approximately equal to or less than the sectional area of the holder member
The support member and the holder member are
A flow sensor, wherein the area is divided into substantially equal parts . 2. The flow sensor according to claim 1, wherein the fitting member is a convex portion. 3. The flow rate sensor according to claim 1, further comprising a guide member that defines an installation angle of the holder member with respect to the inflow direction of the fluid.