JPH07270441A - Wind speed sensor - Google Patents

Abstract

PURPOSE:To provide a wind speed sensor with its smaller number of parts, thereby being capable of being miniaturized, and also being low in manufacturing cost, and having high precision. CONSTITUTION:Temperature sensitive resistors RH and RT are connected to electrodes 6a, 6b, 7a, and 7b conductive to the signal processing circuit, arranged on the board 1 of a hybrid IC (hybrid IC board) constituting a signal processing circuit. A hybrid IC board 1 is shaped so that the electrodes 6a, 6b, and 7a, 7b to which load wires 8a, 8b, 9a, and 9b are connected can be arranged at their opposite positions via a space 11, and the lead wires 8a, 8b, 9a, and 9b of the temperature sensitive resistors RH and RT are connected to the electrodes 6a, 6b, 7a, and 7b arranged at their opposite positions via the space 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wind speed sensor,
More specifically, the present invention relates to a wind velocity sensor that detects the wind velocity by utilizing the heat radiation of a heating element corresponding to the flow velocity of gas.

[0002]

2. Description of the Related Art As a wind speed sensor for detecting the flow velocity (wind speed) of a gas, a wind turbine type wind speed sensor for detecting the number of revolutions of a wind turbine (propeller) or a cup with a generator or tachometer, generation of Karman vortex There are a wind speed sensor that counts the number, a thermal wind speed sensor that uses the heat radiation phenomenon of a heating element, and the like.

Among the above wind speed sensors, the wind turbine type wind speed sensor is the most direct one and has been widely used from the past. However, mechanical stress such as rotation is always applied to the wind speed sensor, and the characteristic deterioration is rapid and maintenance is required. However, there is a problem in that it is difficult to miniaturize and is expensive.

Further, in the Karman vortex type wind velocity sensor, a device for counting the Karman vortex is relatively large in scale, and the cost and responsiveness are not always satisfactory.

On the other hand, there is a thermal type wind speed sensor for detecting the wind speed from the magnitude of the heat radiating action of the air flow on the resistor which heats the resistor.

[0006] This thermal wind speed sensor has been particularly attracting attention in recent years because it can realize high accuracy and high reliability at low cost, and an air flow sensor for an electronically controlled gasoline injection device of an automobile. It is widely used as an air quantity sensor for air conditioning systems.

FIG. 4 is a perspective view showing an example of a conventional thermal wind speed sensor. This wind speed sensor is a wind speed sensor in which a sensor unit and a signal processing electric circuit unit are integrated, and is provided with a heater resistor R _H and a temperature compensation resistor R _{T provided} on a substrate 54 made of epoxy resin or the like. A sensor main body 51 including a sensor section including a hybrid IC 52, a semi-fixed resistor 53, and the like, an upper case member 56a having a window 55, and a lower case. It is formed by being housed in a case 56 composed of a member 56b. Although not particularly shown, a wind speed sensor having a structure in which the sensor unit and the signal processing electric circuit unit are separated is also in practical use.

In this wind speed sensor (FIG. 4), the heater resistor R _H is arranged at a position hit by the wind,
The temperature compensating resistor R _T is used as a resistor for detecting the wind velocity by radiating heat corresponding to the wind velocity, and the temperature compensating resistor R _T has a role of canceling the influence of the ambient temperature of the heater resistor R _H.

As the resistors R _H and R _T ,
When resistors having the same performance are used and the ambient temperature changes, the heater resistor R _H and the temperature compensating resistor R _T have the same resistance value in accordance with the ambient temperature. Since the influence of the ambient temperature is canceled by the resistor R _T , the wind speed can be accurately detected from the heat radiation of the heater resistor R _H without being influenced by the ambient temperature.

FIG. 5 shows an example of the circuit configuration of the conventional thermal wind speed sensor. As shown in FIG. 5, the connection terminal on one side of the heater resistor R _H is connected to the ground side, and the connection terminal on the other side is connected in series with the resistor R ₁ to form the first resistance circuit 62. ing. The connection terminal of one side of the temperature compensation resistor R _T is connected to the ground, connecting terminal of the other side is connected a variable resistor VR ₁ and the series, further the variable resistor VR ₁ and the resistor R ₂ in series The second resistance circuit 63 is formed by being connected.

The output side of the first resistance circuit 62 serves as the first bridge output balancing terminal A, and the second resistance circuit 63
Is connected to the first bridge output balanced end A, and the resistor R ₃ is connected to the second bridge output balanced end B. A resistor bridge circuit is formed by connecting R ₄ and the variable resistor VR ₂ .

The first bridge output balanced end A is connected to the negative side input terminal 66 of the differential amplifier (operational amplifier) 64 functioning as a differential operation circuit, and the second bridge output balanced end B is connected to the differential amplifier 64. Is connected to the positive side input terminal 67 of. The differential amplifier 64 is connected to the transistor 65 for current amplification. The resistor R ₁ ,
As R ₂ , R ₃ and R ₄ , resistors having a resistance temperature coefficient (± 100 ppm / ° C.) smaller than that of the heater resistor R _H and the temperature compensation resistor R _T by one digit or more are used. Therefore, a well-balanced bridge circuit is formed by appropriately selecting the resistance values of the resistors R ₁ , R ₂ , R ₃ , and R ₄ . Therefore, when the ambient temperature changes, the influence of the ambient temperature is canceled by the heater resistor R _H and the temperature compensating resistor R _T , so that the temperature characteristics of the wind speed sensor can be made flat. The variable resistance VR ₁ in the second resistance circuit 63 is used for fine adjustment of the temperature characteristic, and the variable resistance VR ₂ connected to the second resistance circuit 63 changes the output level of the wind speed sensor. It is used to adjust.

In this wind velocity sensor, the temperature of the heater resistor R _H decreases as the velocity of the wind hitting the wind velocity sensor (wind velocity) increases. On the other hand, since the temperature compensating resistor R _T does not generate heat, the temperature does not change. Therefore, the potential at the point A decreases, but the potential at the point B does not change, the output terminal voltage V _out of the differential amplifier 64 increases, and a signal indicating an increase in wind speed is output. On the other hand, when the velocity of the wind hitting the wind velocity sensor (wind velocity) decreases, the temperature of the heater resistor R _H rises by the mechanism reverse to that when the velocity of the wind hitting the wind velocity sensor (wind velocity) increases and the point A As the potential rises, the output terminal voltage V _out of the differential amplifier 64 drops and a signal indicating a wind speed decrease is output.

[0014]

However, in the above-described conventional wind speed sensor, the heater resistor R _H and the temperature compensation resistor R _T are arranged on the substrate 54, and mechanical connection (mounting) is performed. In addition to the above), the heater resistor R _H and the temperature compensating resistor R _T are electrically connected to a wiring (not shown) on the substrate 54 to extract an electric signal, and are composed of the hybrid IC 52 and the like. It led to the signal processing circuit.

Therefore, the mechanical holding of the heater resistor R _H and the temperature compensating resistor R _T and the extraction of the electric signal are separate steps, which complicates the manufacturing process and increases the manufacturing cost. In the case of using a sensor, a sensor unit including at least a heater resistor R _H and a temperature compensating resistor R _T , a holding unit (substrate) thereof, a hybrid IC
However, there is a problem in that the size of the product is increased and the number of parts is increased to increase the manufacturing cost.

The present invention solves the above-mentioned problems, has a small number of parts, can be miniaturized, and has a low manufacturing cost, and further has these characteristics, and is highly accurate and reliable. An object of the present invention is to provide a wind speed sensor having excellent properties.

[0017]

In order to achieve the above object, the wind speed sensor of the present invention uses a signal processing circuit in a wind speed sensor that detects the wind speed by utilizing the heat radiation of a heating element corresponding to the flow velocity of gas. A hybrid IC which constitutes the hybrid IC; and at least one temperature-sensitive resistor which is arranged on a substrate of the hybrid IC (hybrid IC substrate) and which is connected to an electrode electrically connected to the signal processing circuit. To do.

Further, as the temperature sensitive resistor, a lead wire type temperature sensitive resistor having lead wires attached to the resistor body is used, and the shape of the hybrid IC substrate is connected to the lead wires of the temperature sensitive resistor. , A shape in which a pair of electrodes are arranged at positions facing each other through a space, and connecting the lead wire of the temperature sensitive resistor to the electrodes arranged at positions facing each other through the space. Thus, the temperature sensitive resistor is held on the substrate and electrically connected to the signal processing circuit.

Regarding the shape of the hybrid IC substrate, "a shape in which a pair of electrodes are arranged at positions facing each other through a space" means, for example, as shown in FIG. Two protrusions 1 on the upper end side of
a, 1b are provided, as shown in FIG. 2, a hole (substantially square hole) 12 is provided at a predetermined position of the hybrid IC substrate 1, or as shown in FIG. Two protrusions 1 on each of the upper and lower ends
It means various shapes such as a shape where a, 1b and 1c, 1d are provided, such that a portion (space) where the hybrid IC substrate does not exist is formed between the pair of electrodes 6a, 6b and 7a, 7b. However, a shape other than the above shapes can be used.

[0020]

[Function] Since the electrode for connecting the temperature sensitive resistor is arranged on the hybrid IC substrate and the temperature sensitive resistor is connected to this electrode, the mechanical connection (holding) of the temperature sensitive resistor is performed. It becomes possible to perform electrical connection at the same time, and a signal processing circuit including a hybrid IC after mechanical connection is made by holding the temperature sensitive resistor on another substrate like a conventional wind speed sensor. By introducing to, it becomes unnecessary to make a mechanical connection and an electrical connection (picking up an electric signal) separately.

Therefore, a separate substrate for holding the temperature sensitive resistor, wiring on the substrate, etc. are not required, the product can be downsized, and the number of parts can be reduced to reduce the manufacturing process. It is possible to simplify and reduce the manufacturing cost as a whole.

Further, the shape of the hybrid IC substrate is
By forming the electrodes to which the lead wires of the temperature sensitive resistor are connected so as to be opposed to each other through a space, and connecting the lead wires of the temperature sensitive resistor to the electrodes through the space. , If the temperature sensitive resistor is held on the substrate and electrically connected to the signal processing circuit, thermal isolation between the temperature sensitive resistor and the signal processing circuit, or as a temperature sensitive resistor , Heater resistor R _H and temperature compensation resistor R _T
In the case of using, the thermal resistance of the heater resistor R _H , the temperature compensation resistor R _T, and the signal processing circuit can be surely thermally separated, and the small and highly accurate wind speed sensor can be used. It will be possible to obtain.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a wind speed sensor according to an embodiment of the present invention.

The wind speed sensor of this embodiment comprises a substrate (hybrid IC substrate) 1 made of alumina which constitutes a hybrid IC functioning as a signal processing circuit, an operational amplifier 2 arranged on the hybrid IC substrate 1, and an amplifier for current amplification. Transistor 3, temperature characteristic adjusting trimming resistor 4, offset adjusting trimming resistor 5, electrodes 6a, 6b, 7a, 7b electrically connected to the signal processing circuit, heater resistor R _H
And a temperature compensating resistor R _T.
It should be noted that signal extraction pins 10 are arranged on both left and right ends of the hybrid IC substrate 1.

In this embodiment, the heater resistor R _H
Is an axial lead type resistor (having a resistance value of 10 to 100) having a cylindrical shape and lead wires 8a and 8b on both end sides.
Ω), and as the temperature compensating resistor R _T , an axial lead type resistor (having a resistance value of 500 Ω to 10 kΩ) similarly having a cylindrical shape and having lead wires 9a and 9b at both ends is used. .

Further, the heater resistor R _H and the temperature compensating resistor R _T have the same shape and the same shape in order to minimize the temperature compensation delay as the wind speed sensor when the ambient temperature changes abruptly. It is dimensioned.

As the hybrid IC substrate 1, a substrate having a shape in which two projecting portions 1a and 1b are provided on the upper end portion is used, and the electrodes 6a, 6b and 7a, 7b have tips of the projecting portions 1a and 1b. It is arranged on the side. The heater resistor R _H and the temperature compensating resistor R _T are connected to the lead wires 8a, 8b and 9a, 9 respectively attached to both ends thereof.
b through the space 11 to the electrodes 6a, 6b and 7a, 7
It is mechanically held on the hybrid IC substrate 1 and electrically connected to the signal processing circuit by being connected to b by a method such as soldering.

In this embodiment, the heater resistor R is used.
_{Although H} is arranged on the upper side and the temperature compensating resistor R _T is arranged on the lower side, they may be arranged so that their positions are reversed.

Further, since the circuit configuration of the wind speed sensor described above is equivalent to the circuit configuration of the conventional wind speed sensor described above (FIG. 5), the description of the circuit configuration of the conventional wind speed sensor will be incorporated by reference. Omit it.

In the wind velocity sensor of this embodiment, the electrodes 6a, 6b and 7a, 7b to which the heater resistor R _H and the temperature compensation resistor R _T are connected are connected to the hybrid IC substrate 1.
The heater resistor R _H and the temperature compensating resistor R _T are arranged on the upper side.
The lead wires 8a, 8b and 9a, 9b of the electrodes 6a,
6b and 7a, 7b are connected,
It is possible to simultaneously perform the mechanical connection of the heater resistor R _H and the temperature compensation resistor R _T and the electrical connection to the signal processing circuit. Therefore, unlike the conventional wind speed sensor, it is not necessary to provide another substrate for holding the temperature sensitive resistor or wiring on the substrate, which makes it possible to downsize the product and reduce the number of components. The cost can be reduced. Further, since the manufacturing process can be simplified, the cost as a whole can be reduced.

Further, as the temperature sensitive resistor, an axial lead type heater resistor R _H and temperature compensation resistor R _T having lead wires 8a, 8b and 9a, 9b attached to both ends of the resistor body are used. , The shape of the hybrid IC substrate 1 is changed to an electrode 6a to which the lead wires 8a, 8b and 9a, 9b of the heater resistor R _H and the temperature compensation resistor R _T are connected.
6b and 7a, 7b are provided with protrusions 1a, 1b which can be arranged at positions facing each other through the space 11, and electrodes 6a which are arranged at positions facing each other through this space 11 , 6b, and 7a, 7b, heater resistor R
_H , lead wires 8a, 8b and 9 of the temperature compensating resistor R _T
By connecting a and 9b, the heater resistor R _H ,
It becomes possible to surely perform thermal isolation between the temperature compensating resistor R _T and the signal processing circuit.

That is, in the wind speed sensor of the above embodiment, the lead wires 8a, 8b and 9a, 9b of the heater resistor R _H and the temperature compensating resistor R _{T have} a diameter of 0.1-0.1.
The resistance for the heater that has generated heat by using a thin wire of about 0.3 mm, more preferably about 0.1 to 0.2 mm, or a metal wire with low thermal conductivity such as platinum wire or nickel wire. The heat of the body R _H can be suppressed from being transferred from the hybrid IC substrate 1 to the temperature compensating resistor R _T via the lead wires 8a and 8b. Further, it is possible to prevent the heat generated in the current amplification transistor 3 of the signal processing circuit from being transferred to the heater resistor R _H and the temperature compensation resistor R _T to cause an error.

This will be described below by using mathematical expressions. The heat quantity dQ passing through the minute cross-sectional area dA in a unit time is dQ = −λ (dθ / dx) dA (1) (where λ: thermal conductivity, dθ / dx: temperature gradient in the longitudinal direction) according to Fourier's law. ).

For example, in the wind speed sensor shown in Embodiment 1 (FIG. 1), the width W of the protrusions 1a and 1b is 3 mm, the thickness of the hybrid IC substrate 1 is 0.3 mm, and the lead wires 8a, 8b and 9a, 9b. Diameter of 0.2 mm; protrusions 1a, 1b
The cross-sectional area S ₁ of S ₁ = 0.3 mm (thickness) × 3 mm (width W) = 0.9 mm ² The cross-sectional area S ₂ of the lead wires 8 a, 8 b and 9 a, 9 b of R _H , R _T is S ₂ = _π becomes × 0.1mm ² = 0.031mm ^2. On the other hand, a hybrid IC substrate 1 made of alumina
Has a thermal conductivity of 20 W / m · ° C, lead wires 8a, 8b,
If the material used for 9a and 9a is a platinum wire, its thermal conductivity is 72 W / m · ° C.

Therefore, when the temperature gradient is constant, the amount of heat dQ ₁ transmitted through the hybrid IC substrate ₁ and the lead wire 8
The relationship between the heat quantities dQ ₂ transmitted through a, 8b and 9a, 9b is as follows. dQ ₁ / dQ ₂ = (20 × 0.9) / (72 × 0.031) = 8.06 (2)

That is, in this case, the heat conduction in the lead wires 8a, 8b and 9a, 9b per unit time is ⅛ or less as compared with that of the hybrid IC substrate 1.

Therefore, by adopting the structure of the above embodiment, a hybrid IC substrate made of alumina or the like can be used without using a substrate having a low thermal conductivity such as epoxy resin unlike the conventional wind velocity sensor. It is possible to form a temperature-sensitive resistor on each of them and thermally separate them at a level that does not hinder practical use.

In the above embodiment, the trimming resistor 4 for adjusting the temperature characteristic and the trimming resistor 5 for adjusting the offset of the wind speed sensor are made of a hybrid IC made of alumina.
The resistors printed on the substrate 1 are used. After all the components are mounted on the hybrid IC substrate 1, it is possible to perform trimming by a method such as laser trimming to perform final adjustment as a wind speed sensor. Therefore, compared to the conventional wind speed sensor that uses a trimmer resistor to adjust the resistance by rotating the shaft, the trimmer resistor is not required, which reduces costs, improves trimming work efficiency, and improves long-term stability of the resistor. Can be achieved.

In the above embodiment, the hybrid IC is used.
The substrate 1 has a shape in which two projecting portions 1a and 1b are provided at one end thereof, and electrodes 6a and 6b and 7a and 7b, which are opposed to each other with a space 11 in between, have a heater resistor R. _H , lead wires 8a, 8 on both ends of the temperature compensating resistor R _T
However, the shape of the hybrid IC substrate is not limited to the shape of the above embodiment, and for example, as shown in FIG. Electrodes (6a, 6b) and 7a, 7 which are formed in a shape having a hole (substantially square hole) 12 in the
The lead wires 8a, 8b and 9a, 9b on both ends of the heater resistor R _H and the temperature compensation resistor R _T are connected to b,
Alternatively, as shown in FIG. 3, two protrusions 1a, 1b and 1c, 1d are provided on both upper and lower ends of the hybrid IC substrate 1, and the heater resistor R _H and the temperature compensating resistor R _T are placed on the upper and lower sides. It is also possible to arrange them separately. 2 and 3, each reference numeral indicates the same or corresponding portion as in FIG. Also, hybrid I
The shape of the C substrate may be any other shape as long as it is possible to connect the lead wire of the temperature sensitive resistor to the electrodes arranged at the positions opposed to each other through the space.

Further, in the above embodiment, the case where the axial lead type temperature sensitive resistor is used has been described, but the wind velocity sensor of the present invention is not limited to the axial lead type temperature sensitive resistor, and so-called radial lead type. It is also possible to use a mold type temperature sensitive resistor.

In other respects, the present invention is not limited to the above-described embodiment, and the positions of the electrodes on the hybrid IC substrate, the thickness of the hybrid substrate and the thickness of the lead wire, the lead wire and the electrode With respect to the connection method, the material of the lead wire and the hybrid IC substrate, the configuration of the signal processing circuit, and the like, various applications and modifications can be made within the scope of the invention.

[0042]

As described above, in the wind speed sensor of the present invention, the temperature sensitive resistor is connected to the electrodes arranged on the substrate (hybrid IC substrate) of the hybrid IC that constitutes the signal processing circuit. Therefore, it becomes possible to perform mechanical connection (holding) and electrical connection of the temperature sensitive resistor at the same time, and another substrate for holding the temperature sensitive resistor or the same as the conventional wind velocity sensor can be used. Wiring on the board is unnecessary.

Therefore, the product can be downsized, the number of parts can be reduced, the manufacturing process can be simplified, and the manufacturing cost as a whole can be reduced.

Furthermore, the shape of the hybrid IC substrate is
By forming the electrodes to which the lead wires of the temperature sensitive resistor are connected to each other at positions facing each other through a space, and connecting the lead wires of the temperature sensitive resistor to the electrodes through the space. , When the temperature sensitive resistor is held on the substrate and electrically connected to the signal processing circuit, a resistor for the heater may be provided between the temperature sensitive resistor and the signal processing circuit or as a temperature sensitive resistor. When the body and the temperature compensating resistor are used, it becomes possible to thermally and reliably separate the heater resistor, the temperature compensating resistor and the signal processing circuit.
A small and highly accurate wind speed sensor can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a wind speed sensor according to an embodiment of the present invention.

FIG. 2 is a diagram showing a wind speed sensor according to another embodiment of the present invention.

FIG. 3 is a diagram showing a wind speed sensor according to still another embodiment of the present invention.

FIG. 4 is an exploded perspective view showing a conventional wind speed sensor.

FIG. 5 is a diagram showing a circuit configuration of a wind speed sensor.

[Explanation of Codes] 1 Substrate (Hybrid I
C substrate) 1a, 1b, 1c, 1d protruding portion 2 operational amplifier 3 current amplification transistor 4 temperature characteristic adjusting trimming resistor 5 offset adjusting trimming resistor 6a, 6b, 7a, 7b electrode 8a, 8b, 9a, 9b lead wire 10 Signal extraction pin 11 Space 12 hole _RH Heater resistor _RT Temperature compensating resistor

Claims (2)

[Claims] 1. A wind speed sensor for detecting a wind speed by utilizing heat radiation of a heating element corresponding to a gas flow velocity, a hybrid IC constituting a signal processing circuit, and a substrate of the hybrid IC (hybrid IC substrate).
A wind speed sensor, comprising: at least one temperature-sensitive resistor, which is connected to an electrode electrically connected to the signal processing circuit provided above. 2. The temperature sensitive resistor is a lead wire type temperature sensitive resistor having a lead wire attached to a resistor body, and the shape of the hybrid IC substrate is connected to the lead wire of the temperature sensitive resistor. , A shape such that a pair of electrodes are arranged at positions facing each other through a space, and connecting the lead wire of the temperature sensitive resistor to the electrodes arranged at positions facing each other through the space. The wind speed sensor according to claim 1, wherein the temperature sensitive resistor is held by the substrate and electrically connected to the signal processing circuit.