JP6040637B2 - Pressure sensor - Google Patents

Description

  The present invention relates to a pressure sensor in which a port portion in which a pressure introduction hole is formed is assembled to a case, and a pressure detection element is provided in a pressure detection chamber formed between the case and the port portion.

  Conventionally, a pressure detection element that assembles a port portion in which a plurality of pressure introduction holes are formed in a case and outputs a sensor signal corresponding to the pressure of a measurement medium to a pressure detection chamber configured between the case and the port portion Has been proposed (see, for example, Patent Document 1).

  Specifically, in such a pressure sensor, the port portion is configured with a chamber whose wall surface is tapered by widening the end portion on the case side of each pressure introducing hole. Including a pressure detection chamber.

  According to such a pressure sensor, when water droplets are generated in the pressure detection chamber due to condensation, the water droplets slide down the wall surface of the tapered room and are discharged to the outside from each pressure introducing hole. That is, the amount of water droplets passing through each pressure introduction hole is reduced, and the pressure introduction hole can be prevented from being blocked.

JP 2008-292268 A

  However, although the pressure sensor can prevent the pressure introduction holes from being blocked, it is difficult to completely prevent the pressure introduction holes from being blocked. And even if a pressure introduction hole is obstruct | occluded, a pressure detection element continues outputting the signal according to the pressure of the obstruct | occluded space.

  For this reason, for example, when a pressure sensor is mounted on a vehicle and used to measure the intake pressure in the intake manifold, the intake pressure cannot be measured accurately, which may cause a reduction in fuel consumption. There is a problem of having sex.

  An object of this invention is to provide the pressure sensor which can judge whether the pressure introduction hole was obstruct | occluded in view of the said point.

  In order to achieve the above object, according to the first aspect of the present invention, a case (10) having a recess (11) formed on one surface and a pressure mounted on the recess and outputting a sensor signal corresponding to the pressure of the measurement medium. A pressure detection chamber (80) is formed between the detection element (30) and one end (22) side of the case, and a pressure introduction hole (introducing a measurement medium into the pressure detection chamber). 21) formed with a port portion (20), a heat generation means (90) provided in the pressure detection chamber, and a diagnosis means (40) for diagnosing blockage of the pressure introduction hole based on the sensor signal, The diagnostic means is characterized in that when the heat generating means is generating heat, a self-diagnosis is performed to determine that the pressure introducing hole is closed when the sensor signal becomes a signal proportional to the heat generated by the heat generating means.

  In such a pressure sensor, when the pressure introduction hole is closed, the pressure detection chamber becomes a sealed space. For this reason, it is possible to determine whether or not the pressure introducing hole is closed by performing a self-diagnosis to determine whether or not the sensor signal becomes a signal proportional to the heat generating means.

  For example, as in the second aspect of the present invention, the diagnostic means can determine that the pressure introduction hole is closed when the sensor signal is proportional to the heat generation period of the heat generation means.

Further, as in the third aspect of the invention, the diagnostic means can determine that the pressure introduction hole is closed when the sensor signal is proportional to the temperature of the pressure detection chamber .

  And like invention of Claim 7, a pressure detection element shall be comprised using the sensor chip (30a) formed in the state in which the gauge resistance which has temperature dependence comprises a bridge circuit. be able to.

  According to this, the responsiveness (reactivity) of the sensor signal with respect to temperature can be increased, and the accuracy of self-diagnosis can be improved.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a figure which shows the cross-sectional structure of the pressure sensor in 1st Embodiment of this invention. It is a figure which shows the cross-sectional structure of the pressure sensor in 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings. Note that the pressure sensor of this embodiment is preferably applied to an intake pressure sensor that is attached to an intake manifold of a vehicle and measures the pressure in the intake manifold.

  As shown in FIG. 1, the pressure sensor of this embodiment is configured by assembling a port portion 20 to a case 10, and the port portion 20 is formed with a pressure introduction hole 21 for introducing a measurement medium. Yes.

  The case 10 is manufactured, for example, by molding a resin such as PPS (polyphenylene sulfide) or PBT (polybutylene terephthalate), and the recess 11 is formed on one surface.

  The case 10 includes a plurality of terminals 12 (only one is shown in FIG. 1) connected to the outside. Each terminal 12 is held in the case 10 by being integrally formed by insert molding.

  Specifically, the plurality of terminals 12 are provided in the case 10 such that one end is exposed in the recess 11 and the other end is exposed (projected) in the opening 13. The portion of the terminal 12 exposed in the opening 13 can be connected to an external device (external wiring member or the like) not shown.

  Such a terminal 12 is made of a conductive material such as copper, and a portion exposed in the recess 11 is gold-plated to function as a bonding pad.

  In the recess 11 formed in the case 10, a pressure detection element 30 for detecting the pressure of the measurement medium and a circuit chip 40 for performing predetermined signal processing are mounted via an adhesive (not shown).

  The pressure detection element 30 includes a sensor chip 30a and a pedestal 30b. Specifically, the sensor chip 30a is formed with a diaphragm (thin wall portion) formed by forming a recess from the back surface, and a gauge resistor is formed on the diaphragm so as to form a bridge circuit. That is, in the sensor chip 30a of the present embodiment, when pressure is applied to the diaphragm, the resistance value of the gauge resistance changes, the voltage of the bridge circuit changes, and the semiconductor diaphragm outputs a sensor signal corresponding to the change in voltage. Of the formula.

  Note that the gauge resistance of the present embodiment is a resistance having a temperature dependency in which the resistance value changes according to the temperature, and is configured by, for example, a P-type diffusion resistance.

  And the pressure detection element 30 is comprised by anodically joining the base 30b to the back surface of such a sensor chip 30a. Note that a reference chamber is formed between the sensor chip 30a (diaphragm) and the pedestal 30b. However, the reference chamber may be set to a vacuum pressure or an atmospheric pressure.

  The circuit chip 40 is formed with various circuits for generating a drive signal for the pressure detecting element 30 and correcting a temperature characteristic of the sensor signal. In the present embodiment, the circuit chip 40 is also provided with a drive circuit for generating heat, which will be described later, and a control circuit for determining whether or not the pressure introducing hole 21 is closed from the sensor signal. Yes. In the present embodiment, this control circuit corresponds to the diagnostic means of the present invention.

  The pressure detecting element 30 and the circuit chip 40 are electrically connected by a wire 51, and the circuit chip 40 and the terminal 12 are electrically connected by a wire 52. For the wires 51 and 52, for example, gold or aluminum is used.

  Further, the recess 11 of the case 10 is filled with a protective member 60 made of fluorine gel, fluorine rubber or the like having excellent electrical insulation and chemical resistance. 12, the pressure detection element 30, the circuit chip 40, and the wires 51 and 52 are sealed and protected.

  In the present embodiment, the protective member 60 has a two-layer protective structure including a fluorine-based rubber material 60a having a relatively high Young's modulus and a fluorine-based gel material 60b having a relatively low Young's modulus. A fluorine-based rubber material 60 a or the like is disposed on the bottom surface side of the recess 11.

  The port portion 20 is produced by molding a resin such as PPS (polyphenylene sulfide) or PBT (polybutylene terephthalate), as in the case 10, and guides the measurement medium to the pressure detection element 30. It is.

  And the port part 20 is connected with the case 10 by the adhesive 70 etc. which are excellent in chemical resistance, such as a hard epoxy resin, and are highly elastic so that the one surface of the case 10 may be covered. As a result, a pressure detection chamber 80 is configured between the case 10 and the port portion 20.

  Further, the port portion 20 has the other end 23 projecting in a direction opposite to the case 10, and a pressure introduction hole 21 communicating with the pressure detection chamber 80 from the other end 23 in the projecting direction is formed therein. . The measurement medium is introduced into the pressure detection chamber 80 via the pressure introduction hole 21.

  Furthermore, a chamber 24 having a tapered wall surface is formed in the port portion 20 by widening the end portion of the pressure introduction hole 21 on the case 10 side. That is, the pressure detection chamber 80 is configured between the chamber 24 and the case 10.

  In the pressure detection chamber 80, a heating element 90 corresponding to the heating means of the present invention that generates heat when energized, such as a resistor or a diode, is disposed. In the present embodiment, the heating element 90 is disposed on the wall surface constituting the room 24 and is electrically connected to the circuit chip 40 via a wire or the like (not shown). That is, heat can be appropriately generated according to the drive signal from the circuit chip 40.

  Moreover, the O-ring 100 is provided in the outer peripheral part by the side of the other end 23 among the port parts 20, and the pressure sensor of this embodiment can ensure the airtightness between a to-be-attached member and the port part 20. FIG. It can be done.

  The above is the configuration of the pressure sensor in the present embodiment. Next, the operation of the pressure sensor will be described.

  The pressure sensor is used, for example, even when attached to an intake manifold of a vehicle. When the measurement medium (air mixture in the intake manifold) is introduced into the pressure detection chamber 80 via the pressure introduction hole 21, a sensor signal corresponding to the pressure of the measurement medium is output from the pressure detection element 30.

  Therefore, the circuit chip 40 generates a calculation signal obtained by performing temperature characteristic correction, amplification processing, and the like on the sensor signal, and outputs this calculation signal to an external circuit. Thereby, the external circuit measures the pressure of the measurement medium based on the calculation signal.

  Further, the circuit chip 40 outputs a drive signal for causing the heating element 90 to generate heat at a predetermined period by the drive circuit, and a sensor signal (before performing the temperature characteristic correction) when the heating element 90 is generated by the control circuit. The self-diagnosis is performed to determine whether or not the pressure introduction hole 21 is closed from the signal (1).

  That is, when the pressure introduction hole 21 is closed, the pressure detection chamber 80 is a sealed space. Therefore, when the heating element 90 is heated with the pressure introduction hole 21 closed, assuming that the pressure is P, the volume is V, the number of moles is n, the gas constant is R, and the gas temperature is T, PV = nRT According to (Boyle-Charle's law), the pressure of the measurement medium increases in proportion to the heat generation of the heating element 90. That is, for example, the first pressure when the heating element 90 starts to generate heat is proportional to the second pressure after the heating element 90 has generated heat for a predetermined period.

  Therefore, the circuit chip 40 (control circuit) determines that the pressure introduction hole 21 is closed when the sensor signal is proportional to the heat generated by the heat generating body 90 when the heat generating body 90 is generating heat, and the external A signal indicating that the pressure introduction hole 21 is blocked in the circuit is output to the external circuit. Thereby, when a pressure sensor is mounted and used in a vehicle, the passenger | crew can detect the malfunction of a pressure sensor.

When the pressure sensor is mounted on a vehicle and used, the pressure of the measurement medium hardly changes when the accelerator is off (stopped), but when the accelerator is on (running),
Even when the pressure introduction hole 21 is not closed, the pressure of the measurement medium changes in proportion to the heat generation of the heating element 90 by chance when the heating element 90 is heated to perform self-diagnosis. There is.

For this reason, when performing a self-diagnosis when the accelerator is on, for example, when the heating element 90 generates heat a plurality of times and the sensor signal becomes a signal proportional to each heat generation of the heating element 90, the pressure introduction hole 21 is blocked. You may make it determine with it. By performing self-diagnosis when the accelerator is turned on in this way, it is unlikely that the pressure of the measurement medium changes simultaneously with the heat generation of the heating element 90, so that erroneous determination can be suppressed.

As described above, the pressure sensor according to the present embodiment includes the heating element 90 in the pressure detection chamber 80 and causes the heating element 90 to generate heat, so that the circuit chip 40 (control circuit) performs self-diagnosis. For this reason, it can be determined whether or not the pressure introduction hole 21 is closed. For example, in the case where the pressure introduction hole 21 is mounted on a vehicle and used, the occupant can detect a malfunction of the pressure sensor.

  In the present embodiment, the gauge resistance is a temperature-dependent resistance. For this reason, the responsiveness (reactivity) of the sensor signal with respect to temperature can be increased, and the accuracy of self-diagnosis can be improved.

(Second Embodiment)
A second embodiment of the present invention will be described. In the present embodiment, the heating element 90 is formed on the circuit chip 40 with respect to the first embodiment, and the other parts are the same as those in the first embodiment, and thus the description thereof is omitted here.

  As shown in FIG. 2, in the pressure sensor of this embodiment, the heating element 90 is not disposed in the pressure detection chamber 80, and the heating element 90 is formed on the circuit chip 40. That is, a resistor, a diode, or the like that generates heat when energized in the circuit chip 40 is formed.

  According to this, since it is not necessary to prepare the heating element 90 separately from the circuit chip 40, the assembly process can be simplified.

(Other embodiments)
In the first embodiment, the example in which the circuit chip 40 is disposed in the pressure detection chamber 80 has been described. However, the circuit chip 40 may be disposed outside the pressure detection chamber 80. Further, for example, when used by being mounted on a vehicle, the vehicle ECU may have the same function as the circuit chip 40.

  In each of the above embodiments, the pressure detection element 30 and the circuit chip 40 may be integrally formed. That is, in the first embodiment, various circuits that exhibit the same function as the circuit chip 40 may be formed in the sensor chip 30a. In the second embodiment, various circuits that exhibit the functions of the circuit chip 40 and the heating element 90 may be formed in the sensor chip 30a.

  Further, in each of the above-described embodiments, the gauge resistance formed on the sensor chip 30a has a temperature dependence, but the gauge resistance may not have a temperature dependence.

  In addition, a pressure detection hole is closed by disposing a temperature detection element in the pressure detection chamber 80 and determining whether or not the pressure of the measurement medium increases in proportion to the temperature detected by the temperature detection element. You may make it determine whether it is.

DESCRIPTION OF SYMBOLS 10 Case 20 Port part 21 Pressure introduction hole 30 Pressure detection element 40 Circuit chip (diagnosis means)
80 Pressure detection chamber 90 Heating element

Claims (7)

A case (10) having a recess (11) formed on one surface;
A pressure detecting element (30) mounted in the recess and outputting a sensor signal corresponding to the pressure of the measurement medium;
A pressure detection chamber (80) is formed between the one end (22) side and the one surface of the case by being connected to the case, and a pressure introduction hole (21) for introducing the measurement medium into the pressure detection chamber. A formed port portion (20);
Heating means (90) provided in the pressure detection chamber;
Diagnostic means (40) for diagnosing blockage of the pressure introduction hole based on the sensor signal,
The diagnostic means performs a self-diagnosis that determines that the pressure introducing hole is closed when the sensor signal becomes a signal proportional to the heat generated by the heat generating means when the heat generating means is generating heat. A featured pressure sensor.   The pressure sensor according to claim 1, wherein the diagnosis unit determines that the pressure introducing hole is closed when the sensor signal is proportional to a heat generation period of the heat generation unit. The pressure sensor according to claim 1, wherein the diagnosis unit determines that the pressure introducing hole is closed when the sensor signal is proportional to the temperature of the pressure detection chamber . The pressure detection chamber includes a temperature detection element that detects the temperature of the pressure detection chamber,
The pressure sensor according to claim 3, wherein the diagnosis unit performs self-diagnosis based on a temperature detected by the temperature detection element. 5. The pressure sensor according to claim 1, wherein the heat generation unit and the diagnosis unit are provided in a circuit chip disposed in the pressure detection chamber .   The pressure sensor according to claim 1, wherein the heat generation unit and the diagnosis unit are provided in the pressure detection element.   The pressure detection element is configured by using a sensor chip (30a) formed in a state in which a gauge resistance having temperature dependency forms a bridge circuit. The pressure sensor described in 1.

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