JP6692698B2 - Pressure sensor - Google Patents

Description

  The present invention relates to a pressure sensor, and more particularly to a pressure sensor for improving the reliability of a sensor suitable for detecting a rail pressure in a common rail fuel injection control device.

In a so-called common rail fuel injection control device, rail pressure is one of the important factors that affect the quality of fuel injection control, and its detection requires high stability and reliability. It is well known that various techniques have been proposed and put to practical use not only in itself but also in a processing method of a detection signal and the like (see, for example, Patent Document 1).
As a sensor used for detecting the rail pressure of the common rail fuel injection control device, a sensor configured to output one detection signal is usually used.

JP, 2009-168616, A

  However, if the output is abnormal due to a sensor failure or wire breakage with only one detection signal, it may be difficult to immediately determine whether the detection signal is normal, or a reliable suboptimal measure. However, it is difficult to say that the reliability and safety against failures are always satisfactory.

  The present invention has been made in view of the above circumstances, and provides a pressure sensor with further improved reliability against sensor failure.

In order to achieve the above object of the present invention, the pressure sensor according to the present invention,
A first sensor element, an insulating layer, and a second sensor element are sequentially laminated on a surface opposite to one surface of the diaphragm that receives a pressure from the object to be measured, and the first and second sensor elements are stacked. Uses a strain gauge,
The first and second sensor elements are each configured to be able to output a voltage change corresponding to the deformation of the diaphragm.

  According to the present invention, the voltage change corresponding to the deformation of the diaphragm is detected by the two sensor elements, and the two sensor elements can separately output the voltage change, whereby the reliability can be remarkably improved by duplicating the sensor. The effect is that it can be done.

It is a longitudinal cross-sectional view of the pressure sensor module in the embodiment of the present invention. It is the whole perspective view including a partial longitudinal section of a pressure sensor in an embodiment of the invention. It is a top view which showed typically the pressure sensor element assembly which comprises the pressure sensor in embodiment of this invention. It is the equivalent circuit schematic diagram showing the equivalent circuit of the pressure sensor in embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4.
The members, arrangements, etc. described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.
First, a schematic overall configuration of the pressure sensor according to the embodiment of the present invention will be described with reference to FIG.
The pressure sensor module 50 according to the embodiment of the present invention is used to detect a rail pressure used for fuel injection control or the like in a common rail fuel injection control device.

The pressure sensor 2 according to the embodiment of the present invention is housed in a casing 1 for attachment to a common rail (not shown), and constitutes a pressure sensor module 50 together with the casing 1.
The pressure sensor module 50 according to the embodiment of the present invention is roughly divided into a casing 1 and a pressure sensor 2.
The casing 1 has a columnar screw connection portion 3, a plate member 4 attached to the screw connection portion 3 so that the pressure sensor 2 is provided therein, and a PCB circuit board arranged on the plate member 4. 5, a metal housing 6 provided so as to cover the PCB circuit board 5, and a connector housing 7 provided so as to fix the metal housing 6 to each other. ..

The screw connection portion 3 is formed in a hollow cylindrical shape, and a screw portion 3a screwed to a pressure sensor mounting portion of a common rail (not shown) is formed on the outer peripheral surface thereof.
Fuel from a common rail (not shown) flows into a hollow portion 3b formed inside the screw connection portion 3 and reaches the inside of a pressure sensor 2 described later.

A flange 3c is formed on the top side of the screw connection portion 3, that is, on the peripheral edge portion on the side opposite to the portion screwed into the common rail (not shown), and a plate member 4 described later is formed on the flange 3c. It is supposed to be placed.
Further, the opening of the hollow portion 3b on the top side of the screw connection portion 3 is formed so as to project so that the end portion of the pressure sensor 2 is fitted.

The plate member 4 formed in a substantially disc shape has a hollow cylindrical sensor storage portion 4a formed in the central portion thereof, and the pressure sensor 2 is positioned in the sensor storage portion 4a.
The diameter of the sensor housing portion 4a is set to an appropriate size so that it can maintain an appropriate distance from the pressure sensor 2 and does not exceed the outer edge portion of the flange 3c.
Then, in the plate member 4, the peripheral portion of the sensor housing portion 4a is joined to the flange 3c on the surface on the screw connection portion 3 side.

The pressure sensor 2 has two sensor elements 31 and 32 as described later to enable detection of fuel pressure (details will be described later). The vicinity of the top of the pressure sensor 2 is from the sensor storage portion 4a of the plate member 4. It is designed to be exposed in the direction opposite to the screw connection part 3.
A PCB circuit board 5 is provided on the surface of the plate member 4 on the side where the vicinity of the top of the pressure sensor 2 is exposed.

In this PCB circuit board 5, a communication hole 5a is formed in a portion of the plate member 4 located in the sensor housing portion 4a so that the top of the pressure sensor 2 can be exposed to the connector housing 7 side. And the PCB circuit board 5 can be electrically connected. The PCB circuit board 5 is appropriately provided with, for example, a voltage stabilizing circuit, a waveform shaping circuit, and the like required for the pressure sensor 2.
The metal housing 6 is formed in a lid shape and is integrally attached to a lid body portion 7a formed in the connector housing 7, and covers the PCB circuit board 5 together with the lid body portion 7a of the connector housing 7. , The PCB circuit board 5 is fixed to the plate member 4 so as to define a storage portion 8 which is a space for storing the PCB circuit board 5.

The connector housing 7 is a portion to which a connection cable (not shown) for electrical connection with an electronic control unit (not shown) that controls the operation of the vehicle is connected, and is formed in a substantially cylindrical shape. It is roughly divided into a portion 7b and a lid portion 7a formed in a lid shape.
As described above, the lid portion 7a serves to secure the housing portion 8 for the PCB circuit board 5 together with the metal housing 6 and has a plurality of connecting pins 9 made of a conductive member embedded therein. Has become.

  The electrical connection between the PCB circuit board 5 and the pressure sensor 2 is made through a plurality of bonding wires 10, while between the PCB circuit board 5 and the receiving portion 9a of the connection pin 9. An S-shaped spring 11 made of a conductive member is arranged, and the PCB circuit board 5 and the connection pin 9 are electrically connected via the S-shaped spring 11.

    The connection portion 7b is fitted with a connection connector (not shown) provided at an end portion of a connection cable (not shown), and a connection plug (not shown) provided inside the connection connector is connected to a connection pin of the connection portion 7b. When 9 is inserted, electrical connection with an electronic control unit (not shown) not shown is possible.

Next, a more specific configuration of the pressure sensor 2 will be described with reference to FIGS. 2 and 3.
The pressure sensor 2 in the embodiment of the present invention is roughly divided into a diaphragm forming body 20 and a sensor element assembly 30 (see FIG. 2).
The diaphragm forming body 20 has a roughly hollow cylindrical shape with a bottom, and a diaphragm 21 is formed in a central portion on the side opposite to the opening portion. The diaphragm forming body 20 is biased by the pressure of fuel flowing from the opening side. It is possible to transfer.
A sensor element assembly 30 is provided on the diaphragm 21, that is, on the surface of the diaphragm forming body 20 opposite to the opening, as described below.

The sensor element assembly 30 according to the embodiment of the present invention is configured to include the first and second sensor elements 31 and 32 and the insulating mask 33 (see FIG. 3). Note that in FIG. 3, the first sensor element 31 is entirely shaded and the second sensor element 32 is shown in white for the sake of easy understanding and easy understanding.
The first and second sensor elements 31, 32 and the insulating mask 33 are configured by laminating the first sensor element 31, the insulating mask 33, and the second sensor element 32 in this order from the diaphragm 21 side. Has become.
These are not based on the manufacturing technology unique to the present invention, but can be manufactured by using conventionally well-known methods such as vacuum deposition and sputtering in the semiconductor manufacturing technology.
The entire sensor element assembly 30 is covered with a gel member 12 having electrical insulation for protection thereof (see FIG. 1).

  The specific configuration will be described below. First, the first and second sensor elements 31 and 32 basically have the same configuration. Hereinafter, the configuration of the first sensor element 31 will be described. Will be replaced with the description of the second sensor element 32, and the reference numerals of the corresponding constituent elements of the second sensor element 32 will be shown in parentheses after the reference numerals of the constituent elements of the first sensor element 31. To do.

  The first sensor element 31 is a so-called strain gauge including first to fourth resistor bodies 41a to 41d for the first sensor element (first to fourth resistor bodies 42a to 42d for the second sensor element). Is. Here, as is well known, the first to fourth resistor bodies 41a to 41d for the first sensor element (the first to fourth resistor bodies 42a to 42d for the second sensor element) are made of, for example, Cr. It is composed of a so-called metal film such as a (chrome) -N (nitrogen) thin film.

  Each of the first to fourth resistor bodies 41a to 41d for the first sensor element (the first to fourth resistor bodies 42a to 42d for the second sensor element) is a strip-shaped first resistor serving as a basic constituent element. The sensor basic metal film 43A (second sensor basic metal film 43B) is alternately folded back at each end and formed into a so-called zigzag shape, which has a well-known configuration. There is.

  FIG. 3 is a plan view of the sensor element assembly 30 as seen from above on the apex side of the diaphragm 21, that is, on the side opposite to the surface in contact with the fuel. The to the fourth resistors 41a to 41d (the first to the fourth resistors 42a to 42d for the second sensor element) are arranged as described below in the plan view.

First, the first and second resistor bodies 41a and 41b for the first sensor element are so arranged that their longitudinal axes are located in the left-right direction of FIG. It is located in.
On the other hand, the third and fourth resistor bodies 41c and 41d for the first sensor element are arranged such that their longitudinal axis directions are the upper and lower sides of FIG. 3 between the first and second resistor bodies 41a and 41b for the first sensor element. They are arranged so as to be parallel to each other with an appropriate interval therebetween so as to be positioned in the direction.

  The first to fourth resistor bodies 41a to 41d for the first sensor element and the first to fourth resistor bodies 42a to 42d for the second sensor element are the first to fourth resistor bodies for the first sensor element. The first to fourth resistor bodies 42a to 42d for the second sensor element are located inside 41a to 41d, and the first sensor constituting the first to fourth resistor bodies 41a to 41d for the first sensor element. The second sensor basic metal film 43B forming the first to fourth resistor elements 42a to 42d for the second sensor element is arranged so as to be located between the basic metal film 43A for sensors. There is.

  The first to fourth resistor bodies 41a to 41d for the first sensor element (the first to fourth resistor bodies 42a to 42d for the second sensor element) are connected in series so as to form a so-called bridge circuit, and At the mutual connection points, first sensor first to fourth connection electrodes 45a to 45d (second sensor first to first sensors) formed in a rectangular shape via connection wirings 44 as described below. 4 connection electrodes 46a to 46d) are connected and arranged as described below.

  First, the first connection electrode 45a for the first sensor element (the first connection electrode 46a for the second sensor element) is the first resistor 41a for the first sensor element (the second connection element for the second sensor element). The first resistor 42a) is connected to the connection point of the first sensor element third resistor 41c (second element third resistor 42c).

  In addition, the second connection electrode 45b for the first sensor element (the second connection electrode 46b for the second sensor element) is the first resistor 41a for the first sensor element (the second connection element for the second sensor element). The first resistor 42a) is connected to the connection point of the first sensor element fourth resistor 41d (second element fourth resistor 42d).

  Furthermore, the third connection electrode 45c for the first sensor element (the third connection electrode 46c for the second sensor element) is connected to the second resistor 41b for the first sensor element (the second connection element for the second sensor element). The second resistor 42b) is connected to the connection point of the first sensor element fourth resistor 41d (second element fourth resistor 42d).

  Furthermore, the fourth connection electrode 45d for the first sensor element (the fourth connection electrode 46d for the second sensor element) is the second resistor 41b for the first sensor element (for the second sensor element). It is connected to a connection point between the second resistor 42b) and the first sensor element third resistor 41c (second element third resistor 42c).

Then, in the arrangement example shown in FIG. 3, the first to fourth connection electrodes 45a to 45d for the first sensor element and the first to fourth connection electrodes 46a to 46d for the second sensor are It is arranged as described below.
That is, first, the first to fourth connection terminals 46a to 46d for the second sensor element are arranged so as to be located at the four corners of the rectangle in the vicinity of the periphery of the first and second sensor elements 31 and 32. It has been set up.

  In this example, the first and fourth connection electrodes 46a and 46d for the second sensor element have their longitudinal axes on the left side (the left side of the drawing in FIG. 3) of the first and second sensor elements 31 and 32, respectively. The first and fourth connection electrodes 45a for the first sensor element are arranged along the left-right direction of the paper and in parallel with each other at an appropriate interval. , 45d are similarly arranged.

  In addition, the second and third connection electrodes 46b and 46c for the second sensor element are arranged on the right side of the first and second sensor elements 31 and 32 (right side of the drawing in FIG. 3), and their longitudinal axes are in the left-right direction of the drawing. And the first and second connection electrodes 45b and 45c for the first sensor element are arranged in parallel with each other and in parallel with each other at an appropriate interval. It is arranged in the same manner.

  FIG. 4 shows an electrically equivalent circuit of the first sensor element 31, which will be described below. Since the equivalent circuit of the second sensor element 32 is basically the same, in FIG. 4, the reference numeral of the constituent element of the first sensor element 31 corresponds to that of the second sensor element 32. The reference numerals of the constituent elements are shown in parentheses, and the equivalent circuit of the first sensor element 31 will be described instead of the equivalent circuit of the second sensor element 32.

The electrical equivalent circuit of the first sensor element 31 is a so-called bridge circuit as in the conventional case.
The first to fourth connection electrodes 45a to 45d for the first sensor element are used for applying a power supply voltage and outputting a voltage change corresponding to strain, and which terminal is used and how is used. For example, a predetermined power supply voltage Vcc is applied from the outside to the first connection electrode 45a for the first sensor element, and the third connection electrode 45c for the first sensor element is connected to the ground (GND). On the other hand, a usage example is conceivable in which the second and fourth connection electrodes 45b and 45d for the first sensor element are used as output terminals for obtaining the voltage output ΔV.

The outputs of the first and second sensor elements 31 and 32 are input to an electronic control unit (not shown) that performs fuel injection control and the like of the engine and are used for fuel injection control and the like.
Since the pressure sensor module 50 according to the embodiment of the present invention can obtain two outputs as described above, it can be used in the electronic control unit (not shown) as described below, and the common rail type can be used. Further reliability and stability of operation control such as fuel injection control in the fuel injection control device can be ensured.

  For example, in an electronic control unit (not shown), it is preferable to use one of the two outputs obtained by the pressure sensor module 50 for fuel injection control and the like, while using the other output for failure detection. .. In this case, in the failure detection, for example, two outputs are compared, and the output used for fuel injection control or the like has a small change or is stagnant although the output for the failure detection is changed. If the sensor element on the side used for fuel injection control or the like is defective, the pressure sensor module is provisionally provided with the output of the sensor element for failure detection. The stability of the operation can be secured without causing instability of the control operation in the fuel injection control or the like due to the failure of 50.

  It can be applied to a pressure sensor for which further improvement in reliability is desired as compared with the conventional one.

2 ... Pressure sensor 20 ... Diaphragm formation body 21 ... Diaphragm 30 ... Sensor element assembly 31 ... First sensor element 32 ... Second sensor element

Claims (1)

A pressure sensor attached to a common rail of a common rail fuel injection control device for use in detecting rail pressure, comprising:
Comprising a first sensor element and a second sensor element arranged on the opposite side of the surface as the one surface of the diaphragm for receiving the rail pressure, the first sensor element and the second sensor element, strain Using a gauge,
The first sensor element has a zigzag-shaped resistor including a first resistor, a second resistor, a third resistor, and a fourth resistor,
The second sensor element has a zigzag-shaped resistor including a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor,
Wherein on the surface of the diaphragm the first sensor element and the insulating layer and the second sensor element are stacked in this order, and wherein the first resistor and the fifth resistor, and the second resistor second 6 resistors, said 3rd resistor and said 7th resistor, said 4th resistor and said 8th resistor are each extended in the same direction,
It said first sensor element and the second sensor element is a pressure sensor characterized by comprising a voltage change corresponding to the deformation of the diaphragm is capable of outputting each configured.

Images