JP2000186969A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent dew condensate in a pressure detecting chamber from flowing into a pressure introducing pipe, in a pressure sensor provided with the pressure detecting chamber for storing a sensor element for detecting pressure, and a connecting tube for introducing pressure from a measured medium into the pressure detecting chamber. SOLUTION: This pressure sensor 100 is provided with an air chamber 7 as a pressure detecting chamber for storing an element part 2 for detecting a pressure signal, and a connecting tube 3a extended to the downside of the air chamber 7 while communicating with an opening hole 7a provided in the bottom of the chamber 7. A cylindrical protrusion 3c projected upwards from the bottom of the air chamber 7 is formed along the entire circumference of the hole 7a in the bottom of the chamber 7, and the protrusion 3c functions as a weir part for damming dew condensate generated in the air chamber 7 in the periphery of the hole 7a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sensor having a pressure detection chamber containing a sensor element for detecting pressure, and a pressure introducing pipe for introducing pressure from a medium to be measured into the pressure detection chamber.

[0002]

2. Description of the Related Art Conventionally, as this kind of pressure sensor, there is a pressure sensor mounted on a vehicle or the like for measuring an air amount of an internal combustion engine, such as an intake air amount sensor. This pressure sensor is shown in FIG. A pressure detection chamber J4 is defined by a case J1 for partitioning the sensor main body and a cover J3 provided below the case J1 and provided with a pressure introducing pipe J2, and a pressure signal is detected in the pressure detection chamber J4. Element part J6 provided with a sensor chip J5 for storing. Further, as the sensor chip J5, for example, one formed from a semiconductor having a silicon diaphragm can be used.

One end of the pressure introducing pipe J2 has a pressure detecting chamber J.
4 communicates with the pressure detection chamber J4 via a hole J7 provided on the lower wall surface (that is, the upper surface of the cover J3), and the other end extends below the pressure detection chamber J4. Then, the pressure from the medium to be measured (for example, the intake air of the internal combustion engine) introduced from the other end side is introduced from the hole J7 into the pressure detection chamber J4. Then, a pressure change in the pressure detection chamber J4 is detected as a signal output from the sensor chip J5.

[0004]

However, when this type of pressure sensor is used in winter or in a cold region (when used at low temperatures), moisture in the air entering the pressure detection chamber J4 is condensed, and condensed water is removed. If the pressure introduction pipe J2 enters the pressure introduction pipe J2 through the hole J7 and is blocked, in the worst case, the dew condensation water freezes and the pressure introduction pipe J
In some cases, cracks occurred in No. 2 and the predetermined amount of intake air could not be measured. Therefore, for example, there has been a problem that the internal combustion engine becomes malfunctioning or cannot be started.

In view of the above problems, the present invention provides a pressure sensor having a pressure detection chamber containing a sensor element for detecting pressure, and a pressure introduction pipe for introducing pressure from a medium to be measured into the pressure detection chamber. An object of the present invention is to prevent moisture condensed in a pressure detection chamber from entering a pressure introduction pipe.

[0006]

In order to achieve the above object, according to the first aspect of the present invention, a pressure detecting chamber (7) accommodating a pressure signal detecting element (2) is provided. And a pressure introducing pipe (3a) extending below the pressure detection chamber while communicating with a hole (7a) provided on the bottom surface of the pressure detection chamber, and water condensed in the pressure detection chamber on the bottom surface of the pressure detection chamber. A dam portion (3c) for damping around the hole.

[0007] With this configuration, even if water condensed in the pressure detection chamber drops at a low temperature, the water is blocked around the hole, so that it can be prevented from entering the pressure introducing pipe. For this reason, it is possible to prevent the pressure introduction pipe from being clogged or cracked due to icing. Further, the dam section may be constituted by a convex section (3c) projecting upward from the bottom surface of the pressure detection chamber (7).

Further, the invention according to claim 3 is characterized in that the pressure introducing pipe (3a) has a tapered shape whose inner diameter increases from the upper side to the lower side. Even if water enters the pressure introducing pipe or dew forms in the pressure introducing pipe, the condensed water easily falls down due to the tapered shape, so that it can be prevented from remaining in the pressure introducing pipe.

The above-mentioned reference numerals in parentheses are examples showing the correspondence with specific means described in the embodiment described later.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. In the present embodiment, the pressure sensor of the present invention will be described as being applied to measurement of an intake air amount of an engine (internal combustion engine) mounted in an engine room of a vehicle.
The application is not limited to this. FIG. 1 is a cross-sectional view of a pressure sensor 100 according to the present embodiment, and FIG. 2 is a transparent plan view (a transparent view as viewed from the direction indicated by the arrow A in FIG. 1) showing connection of the sensors.

Reference numeral 1 denotes a resin case that partitions the pressure sensor body. The case 1 has a connector 1a for leading out a pressure signal generated in the element section (pressure sensor chip) 2 to the outside.
Are insert-molded in the main body of the case 1. The case 1 has a concave portion 1c for accommodating the element portion 2, a convex portion 1d for fixing the cover 3 with an adhesive 4, and a pressure sensor main body mounted in an engine room of an internal combustion engine (not shown). Mounting stay 1e is formed.

The element portion (pressure sensor chip) 2 is provided with a concave portion 2a for fixing a chip 5 for detecting a pressure signal, and is provided with an amplifier circuit for amplifying a signal of the chip 5. The chip, that is, the amplifier circuit section 6 is integrally formed. Reference numeral 2b denotes a lead frame for taking out signals in the element section 2, which is fixed to the terminal 1b by welding. The chip 5 is connected to the lead frame 2b by a connection line 5a such as a wire bond.

Here, for the chip 5, for example, a Si diaphragm type element in which a reference pressure chamber and a silicon (Si) diaphragm are formed on a semiconductor substrate can be used.
Note that, as shown in FIG. 2, the chip 5 and the amplifier circuit unit 6
Although separate chips are integrally formed by molding with resin or the like, the chip 5 and the amplifier circuit unit 6 may be integrated into one chip (for example, the chip 5).

A cover 3 attached below the case 1
Is a pressure-introducing pipe (a pressure-introducing pipe in the present invention) 3a having a pressure-introducing hole 3b, and a convex portion 1 of the case 1.
d has a concave portion 3 d for fixing with an adhesive 4. The case 1 and the cover 3 are fixed with an adhesive 4, and an air chamber (a pressure detection chamber in the present invention) 7 is defined by the recess 1 c of the case 1 and the upper surface of the cover 3.

The element portion 2 which is welded and fixed to the terminal 1b and accommodated in the concave portion 1c of the case 1 is in a state accommodated in the air chamber 7. A pressure introduction pipe 3a is provided on the upper surface of the cover 3, that is, on the bottom surface of the air chamber 7.
An opening hole (a hole portion in the present invention) 7a is formed as a part of the introduction hole 3b. That is, the pressure introducing pipe 3a communicates with the air chamber 7 through the opening hole 7a.

As shown in FIG. 1, the pressure introducing pipe 3a extends downward from the air chamber 7, and a hose or the like is connected to a tip of the pressure introducing pipe 3a. The pressure from the measurement medium) is introduced into the air chamber 7 through the opening hole 7a. In addition, the introduction hole 3b, that is, the inner diameter portion of the pressure introduction pipe 3a has a tapered shape in which the diameter increases from the upper side to the lower side, and the dew condensation water attached to the introduction hole 3b easily drops downward. 3b is prevented from being blocked.

A cylindrical projection (a dam portion in the present invention) 3c projecting upward from the bottom surface of the air chamber 7 is provided all around the opening hole 7a in the bottom surface of the air chamber 7. . The height of the convex portion 3c is set such that moisture condensed in the air chamber 7 is blocked around the opening hole 7a (that is, the outer peripheral portion of the convex portion 3c). Even if dew condensation occurs and the condensed water attached to the inner wall drops on the bottom surface, the introduction hole 3
b can be prevented.

A taper 3e is formed on the bottom surface of the air chamber 7, that is, on the upper surface of the cover 3 so as to decrease from the periphery of the projection 3c toward the projection 3c, thereby reducing the volume of the air chamber 7. The amount of dew water is reduced so that the dew water easily accumulates on the outer peripheral portion of the projection 3c. Also,
As shown in FIGS. 1 and 2, the position of the opening hole 7 a on the bottom surface of the air chamber 7 and the position of the concave portion 2 a of the element section 2 are offset, and the measurement pressure (air) is directly applied to the connection line 5 a of the chip 5. The connection line (wire bond) 5a is prevented from tilting due to a change in the measurement pressure so as not to be applied.

In the pressure sensor 100 having such a configuration, the pressure from the intake air of the engine (not shown) is introduced into the air chamber 7 from the introduction hole 3b of the pressure introduction pipe 3a through the opening hole 7a. The introduced pressure is transmitted to the Si diaphragm of the chip 5 to generate a signal output (resistance change), which is amplified by the amplifier circuit section 6 and guided to the terminal 1b. Then, a pressure signal is derived from the connector 1a to the outside, and the pressure is obtained by performing signal processing in an external circuit.

According to the present embodiment, the pressure sensor 100 is used in winter or in a cold region (use at low temperatures).
In this case, even if moisture condensed in the air chamber 7 drops, the moisture is blocked around the opening 7a by the projection 3c, so that it is possible to prevent the moisture from entering the introduction hole 3b of the pressure introduction pipe 3a. Therefore, the pressure introduction pipe 3a is closed, or dew condensation freezes inside the introduction hole 3b and the pressure introduction pipe J2
This eliminates cracks in the engine, makes it possible to measure the intake air amount of the engine satisfactorily, and eliminates the problem that the internal combustion engine malfunctions or cannot be started.

As shown in FIG. 3, in the conventional cover J3, a pressure introducing pipe (pressure introducing pipe) J2
For example, when the cover J3 is made of resin, the introduction hole J2a of
There was a certain amount of odor, and it was almost straight from top to bottom. For this reason, when dew condensation water enters the pressure introduction pipe or when dew condensation occurs in the pressure introduction pipe, it is difficult for water to fall down, and problems such as blockage are likely to occur.

On the other hand, in the present embodiment, the introduction hole 3b is tapered so that the diameter of the introduction hole 3b is increased from the upper side to the lower side so that the dew condensation water can easily fall downward. Can be prevented, even if dew condensation occurs inside the introduction hole 3b or condensation occurs in the introduction hole 3b. (Other Embodiments) The opening hole 7 in the bottom of the air chamber 7
A groove may be formed on the entire circumference of the portion a instead of the convex portion 3c, and the dewed water may accumulate in the groove to block the groove, and the groove may function as a dam similarly to the convex portion 3c. .

Further, since the main part of this embodiment is provided on the cover 3, it is needless to say that the other parts may be appropriately designed and changed. In short, the present invention relates to a pressure detection chamber in which an element unit for detecting a pressure signal is housed, and a hole which is provided in a bottom surface of the pressure detection chamber and extends below the pressure detection chamber so as to be measured. The present invention is applicable to a pressure sensor including a pressure introduction pipe for introducing pressure from a medium from the hole into the pressure detection chamber.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a cross-sectional configuration of a pressure sensor according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing connection of the pressure sensor shown in FIG.

FIG. 3 is an explanatory diagram showing a cross-sectional configuration of a conventional pressure sensor.

[Explanation of symbols]

2 ... Element part, 3a ... Pressure introduction pipe, 3c ... Convex part, 7 ...
Air chamber, 7a ... opening hole.

Claims (3)

[Claims] 1. An element section for detecting a pressure signal (2).
And extends below the pressure detection chamber while communicating with a hole (7a) provided on the bottom surface of the pressure detection chamber, and communicates pressure from the medium to be measured with the hole. A pressure introduction pipe (3a) for introducing water from the pressure detection chamber into the pressure detection chamber, and a weir (3c) on the bottom surface of the pressure detection chamber for damping moisture condensed in the pressure detection chamber around the hole. The pressure sensor characterized by being provided with. 2. The pressure sensor according to claim 1, wherein the weir portion is constituted by a projection (3c) projecting upward from a bottom surface of the pressure detection chamber. 3. The pressure sensor according to claim 1, wherein the pressure introducing pipe has a tapered shape whose inner diameter increases from above to below.