JPS59147221A - Semiconductor type flow rate detecting apparatus - Google Patents

Abstract

PURPOSE:To contrive to enhance the durability and response of the titled apparatus, by supporting a first semiconductor chip to which a temp. detecting element is formed and a second semiconductor chip having a heater and a temp. detecting element formed thereto in close vicinity to a casing. CONSTITUTION:For example, four projected support parts 24 are formed to the notch part of a substrate 23 and chips 21, 22 are exposed to an air stream at this part. The substrate 23 is supported in a state received in a casing 112 which is, in turn, constituted of a projected upper casing 25A and a recessed lower casing 25B. The inflow port 112A of the casing 112 is formed into a bell mouth shape so as to allow the air stream to flow into a passage 111 without disturbing the flow thereof into said passage 111. The inner surface X of the upper casing 25A is formed into a structure protruded to a semiconductor chip side so as to obliquely blow the air stream to the chip 22. By this mechanism, a flow rate can be detected with high accuracy without applying the influence of the upstream side chip 21 to the downstream side chip 22.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor flow rate detection device useful, for example, for measuring the intake air flow rate of an engine.

Conventionally, flow needles using platinum resistance wire, such as Thomas meters or hot wire flowmeters, have been known, but since the measuring element exposed to the fluid is a wire, the wires are prone to breakage due to vibrations, shocks, etc. There's a problem.

In addition, a flow needle with a structure in which a resistor film is deposited or printed on an insulator such as a ceramic substrate has been proposed.This is because the measuring element is a film, so C is strong against vibrations, etc. Since the resistor film is formed by vapor deposition or printing, fine WX processing is not possible, and the shape of the measuring element must be enlarged, which increases heat capacity and deteriorates responsiveness. There is.

The present invention has been made in order to eliminate the drawbacks of the prior art described in -1- above, and an object of the present invention is to provide a flow rate detection device that has excellent durability and responsiveness to vibrations, etc.

This purpose, according to the present invention, is to bring the first semiconductor depth in which the temperature detection element is formed and the second one-conductor depth in which the heater and the temperature detection element are formed into close proximity to each other for gauging.
This is achieved by using a configuration that supports ζ.

Hereinafter, embodiments of the present invention shown in the drawings will be described.

FIG. 1 shows an example of a fuel injection spark ignition engine equipped with a semiconductor flow rate detection device according to the present invention. The engine 1 sucks combustion air into the combustion chamber 5 through the air cleaner 2 and the intake conduit 3 when the intake valve 4 is opened. Fuel is injected and supplied from an electromagnetic fuel injection valve 6 installed in the intake conduit 3. The intake air flow rate is controlled by opening and closing the throttle valve 7 provided in the intake conduit 3, and the fuel injection amount is basically controlled by changing the opening time of the injection valve 6 using the electronic control unit 8. The amount is controlled to match the flow rate, with corrections added as necessary.

A rectifying grid 9 is provided immediately downstream of the air cleaner 2. This grid 9 serves to rectify the flow of intake air and improve the accuracy of flow rate measurement by the flow rate detection device.

In the intake system of the engine 1, a semiconductor flow rate detection device 10 is installed in the intake conduit 3 between the slot I-lube 7 and the rectifier grid 9.
1 measures the intake air flow rate of the engine I and inputs an electric signal corresponding to the intake air flow rate to the control unit 8. It consists of a hinge section 11 and a circuit section 12, and the center section 11 is connected to the intake conduit 3.
It is located within ′ζ.

Next, the detection device IO will be explained with reference to FIG. 2, which shows a state in which the detection device IO is attached to the suction conduit 2. Sensor section 11 and circuit section 12
The semiconductor flow rate detector 10 consists of screws lO1 to 104.
is fixed to the suction conduit 3 by.

The sensor section 11 has a fluid passageway Ill in parallel with the flow of fluid in the housing, and a semiconductor dip for detecting the flow rate is installed at the central position of the fluid passage Ill.

The sensor section 11 has a dual inline package type casing 112 having two rows of pins, and the sensor section 11 has two rows of bins 114 that output semiconductor chip signals after being evaluated and sorted by an IC tester or the like. III
It is inserted into the socket 121 and fixed with adhesive so that it will not come off due to vibration or the like.

The circuit section 12 processes the output signal of the semiconductor chip and outputs a signal representing the flow rate from the connector 11.3.

The socket 121 is located in the suction conduit 3 so that the flow passing through the flow path 111 of the sensor section 11 can represent the flow rate of the suction conduit 3 without being affected by the boundary layer on the wall of the suction conduit 3. It stands out. In addition, in order to prevent flow disturbance and increase in pressure loss, the tip of the socket 121 in the flow direction is made at an acute angle.

In the FF13 diagram showing the structure of the sensor section 11, 21 is the semiconductor depth of FF51 installed on the upstream side, in which a temperature detection element is formed on a silicon substrate, and 12 is a semiconductor depth in which a heater element and a temperature detection element are formed on a silicon substrate. This is a second semiconductor depth, which is fabricated, and which is installed downstream and adjacent to the first depth 21.

Reference numeral 23 designates a ceramic substrate, on which a conductive paste is printed and fired to electrically connect the lead pins 114 and the depths 21.22.
2 is soldered using the Furinobutsu bump method.

Note that the substrate 23 has four protruding support portions 24 formed in its cutout portion, and these portions support the depth 21.2.
2 is placed so as to be exposed to the air flow. This results in
The structure is such that only the portion of the ceramic substrate 23 that is necessary for fixing the semiconductor depth and extracting the signal is located in the fluid passage 11, and the amount of heat from the heater of the second semiconductor depth 22 that is taken away by the ceramic substrate 21, Reduces the amount of heat transferred from the ceramic substrate to the gas, and reduces the amount of heat transferred from the ceramic substrate to the gas
I! It uses less electricity. The substrate 23 is made of, for example, P
It is housed and supported in a casing 112 made of PS, and the casing 112 is composed of a convex two-part casing 258 and a concave lower casing 25B.

The inlet 112A of the casing 112 has a bellmouth shape so that the flow can flow into the passage 111 without disturbance.

In addition, in order to prevent the flow of m2 to the unit 1' conductor depth 22 from stagnation due to the boundary layer due to the influence of the first 11 conductor depth 21, the inner surface X (iffl
The -E section of the channel 111 is structured to protrude toward the semiconductor depth so that the flow hits the chip 22 obliquely. With this structure, the flow rate can be accurately detected without the downstream chip 22 being affected by the upstream depth 21.

Next, the configuration of the semiconductor depths 21 and 22 will be explained.

As a semiconductor temperature detection element, a diode or a transistor is formed, and its forward voltage is 2.0 with respect to temperature.
There are two types: one that detects temperature by utilizing the linear characteristic of ~2.5mV/'C, and the other that detects temperature by utilizing the fact that the resistance value of the diffused resistor formed by the diffusion method changes with temperature. Although any method can be considered, in this embodiment, the temperature detection element is formed by a diode. In FIG. 4 showing the upstream semiconductor chip 21, the shaded area is the aluminum electrode. Reference numeral 31 denotes a temperature detection element, which is a diode formed by diffusing N-type impurities and P-type impurities into a silicon substrate 30 and then depositing an aluminum electrode.
It has a high sensitivity of ~12.5 mV/°C.

32 to 3° 5 is a portion of the flip dip bump, which is filled with solder and is fixed in contact with the ceramic substrate 23 at four points. Note that since the chip fixing method using the flip-dip method involves four point contacts, the heat capacity of the base plate can be reduced compared to the alloy method normally used for semiconductors.

In FIG. 5 showing the downstream semiconductor depth 22, numeral 41 is a temperature sensing element, which is composed of five diodes formed on a silicon substrate 40 in the same manner as the element 31. 42 is a heater made of a diffused resistor.

By constructing the heater 42 with a diffused resistor on the silicon substrate 40, the degree of freedom in the shape of the heat generating portion can be increased. 43 to 46 are flip chip bump portions.

Next, the detailed circuit of the circuit section I2 will be explained with reference to FIG. The circuit section 12 processes the detection signal of the sensor section 11 and outputs an output signal representing the flow rate.
A, a power supply circuit 12B, a differential amplifier circuit 1201 output circuit 121, and an offset circuit 12E.

The buffer circuit 12A includes variable resistors 51.52 for adjusting variations in the temperature coefficient of the temperature detection element 31.41.
and a voltage follower operational amplifier (hereinafter referred to as OP amplifier) 53 for detecting the potential of the elements 31 and 41.
Consists of 54.

The power supply circuit 12B generates a stabilized voltage from the battery voltage vB, and includes a leg plate 56 and a capacitor 5.
Consists of 7.58.

The differential amplifier circuit 12c includes resistors 61 to 64 and a capacitor 6.
5.66, OP amplifier 67 and power transistor 6
Diode 3 consisting of 8.69 and dependent on the temperature of the air
The voltage (current) applied to the heater 42 is controlled by differentially amplifying the potential of 1.41 and driving the transistors 68 and 69 accordingly. Note that the capacitor 65 is provided to provide a predetermined time constant in the feedback system.

The output circuit 12D includes a current detection resistor 7o, a resistor 71, an output level adjustment variable resistor 72, and a voltage follower OP.
An amplifier 73 outputs a voltage corresponding to the current flowing through the heater 42 from an OUT terminal.

The offset circuit 12E includes a resistor 75.76, a variable resistor 77, an OP amplifier 78, and a transistor 79, and applies an offset voltage set by the resistor 75.77 to the connection point between the resistor 61 and the resistor 62. That is, the voltage applied to the inverting gate of the OP amplifier 67 is reduced by the offset voltage.

In the above configuration, when power is consumed by the heater 42 of the second semiconductor depth 22 on the downstream side, the heat is transferred to the casing 1.
The gas flowing through the 12 passages 111 is transmitted to the silicon substrate and the ceramic substrate 2 of the second semiconductor depth 22 at the same time.
3, transmitted to the first semiconductor depth 21; Here, compared to the case where a silicon substrate with good thermal conductivity is used and a temperature detection element, a heater, and a temperature detection element are arranged on one chip,
When divided into depths, the heat of the heater 42 is transmitted to the first semiconductor depth 21 through the point contact portion of the flip depth bump and the ceramic substrate with poor heat conduction, so that the temperature of the first semiconductor depth 11 on the upstream side increases. The temperature at the detection element 31 is close to that of the flowing gas, and the temperature at the temperature detection element 31 is close to that of the flowing gas.
A large temperature difference can be obtained between and 41.

In addition, the temperature detection element and heater are solid and not made of cotton (wire), so there is no problem with disconnection, and since they can be manufactured using normal semiconductor manufacturing technology, microfabrication is possible. Smaller size improves responsiveness.

Therefore, the amount of heat generated by the heater 42 is controlled by the circuit section 12 so that the potential difference between the input point and the point B of the diodes 31 and 41 becomes equal to the offset voltage.
The temperature difference is controlled to a predetermined value. When controlled in this way, the power consumed by the heater 42 has a predetermined functional relationship with the flow rate, and increases according to a certain curve with respect to the flow rate.

On the other hand, since the power consumption of the heater 42 is output as a voltage at point C, a signal corresponding to the flow rate is output from the OUT terminal.

Next, a second embodiment of the present invention will be described with reference to FIG. Second
In the embodiment, two ceramic substrates 23Δ, 23B are prepared, and first and second semiconductor depths 21, 22 are formed on each substrate 23A, 23B. By using two ceramic substrates in this way, the temperature of the first and second semiconductor depths 21 and 22 is closer to that of the flowing gas, and the power consumption of the reheater can be reduced compared to the first embodiment. .

Figures 8 and 9 show a third embodiment, in which a hybrid IC circuit is placed on a ceramic substrate that holds a sensor chip, and the detection device including the circuit is miniaturized. . The ceramic substrate 23 has a first semiconductor chip 21 and a second semiconductor chip attached to the hollow part.
In order to insulate the circuit portion I2 from the 4th step 22, the cutout 23 is
1, and the opposite end of the sensor section is a connector 113. This ceramic substrate 23 has housings 112Δ, 11 made of metal such as aluminum or heat-resistant resin.
Insert a piece of rubber or other material between 2B and make holes 232-2.
It is screwed on at part 35.

As described above, the present invention has the effect of being excellent in terms of durability and responsiveness.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an engine equipped with a device according to the present invention, FIG. 2 is a cross-sectional perspective view of the main parts of the device shown in FIG.
FIG. 3 is a partial cross-sectional perspective view of the sensor section shown in FIG. 2;
FIG. 4 is a plan view showing the first semiconductor depth, FIG. 5 is a plan view showing the second semiconductor chip, FIG. 6 is an electric circuit diagram showing the circuit section used in the present invention, and FIG. 7 is a plan view showing the second semiconductor chip. 1 is a partially sectional perspective view showing a second embodiment of the invention, FIG. 8 is a front view showing a third embodiment of the invention, and FIG. 9 is a sectional view taken along the line I--■ in FIG. 12...Circuit section, 21...First semiconductor depth, 2
2...Second semiconductor depth, 23.23A, 23B.
...Ceramic substrate, 31.41...Temperature detection element. 42... Heater, 112... Casing, 121.
··socket. Representative Patent Attorney Takashi Okabe Figure 6 1 1 Figure 9 1'lJ

Claims (8)

[Claims] (1) a casing installed in a flow path, a first semiconductor chip provided in the casing and on which a temperature detection element is formed, and a first semiconductor chip provided in the casing in a position close to the first semiconductor chip; 1. A semiconductor flow rate detection device comprising a heater element and a second semiconductor depth formed with a temperature detection element. (2) The semiconductor flow rate detection device according to claim ff11, wherein the temperature detection element comprises a plurality of diodes connected in series. (3) The semiconductor flow rate detection device according to claim 1, wherein the casing has a dual inline package shape. (4) Said No. Lfl'! A 212-conductor type flow rate detection device according to claim 1, wherein two semiconductor depths are arranged on one ceramic substrate-1 substantially along the flow direction. (5) The mi and second semiconductor depths are respectively arranged on separate ceramic substrates.
Semiconductor type flow rate detection device as described in . (6) The semiconductor flow rate detection device according to claim 4, wherein a circuit section for processing signals from the first and second cliff conductor chips is disposed on the helical substrate -1-. (7) The semiconductor flow rate detection device according to claim 4 or 5, wherein the first and second semiconductor chips are arranged in a notch portion of the ceramic substrate. (8) The semiconductor flow rate detection device according to claim 1, wherein the casing is inserted and fixed into a socket that protrudes into the flow path.