JPS6322506Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake pipe pressure detection device that detects the intake pipe pressure of an engine using a pressure sensor.

Information regarding intake pipe pressure is used in the electronically controlled fuel injection system, the display on the driver's cab instrument panel, and the fuel supply amount control in the carburetor.
Pressure sensors are used as a means to generate electrical signals representative of intake pipe pressure. In the intake pipe pressure detection device, the intake pipe pressure is guided from the intake branch pipe to the diaphragm of the pressure sensor by a rubber pipe, etc., and is conducted by a filter made of metal mesh, non-woven fabric, etc. provided at the intake pipe pressure take-out port. , particles as inclusions in oil, gasoline, and exhaust gases are removed. However, these filters are manufactured using IC pressure sensors, in which a part of a semiconductor single crystal is processed into a thin diaphragm, and a resistance is formed on the diaphragm by impurity diffusion. It was selected to prevent foreign matter from adhering to the rubber diaphragm and metal diaphragm, which are considerably larger than the pressure sensor's diaphragm (2 to 3 mm square), and to avoid delays in pressure propagation. Only large particles larger than 10 μm can be removed.
Therefore, when introducing the intake pipe pressure to the small-area diaphragm of an IC-based pressure sensor, foreign matter that adheres to the diaphragm and causes fluctuations in output characteristics may pass through the filter, causing the IC-based pressure sensor to This has become an impediment to the adoption of

An object of the present invention is to provide an intake pipe pressure detection device that can be applied to an IC pressure sensor and can effectively prevent foreign matter from adhering to the diaphragm of the pressure sensor.

To achieve this object, the present invention provides intake pipe pressure detection by guiding the intake pipe pressure to the diaphragm of the pressure sensor through the intake pipe pressure passage and obtaining an electrical signal related to the intake pipe pressure as the output of the pressure sensor. In the device, the intake pipe pressure passage has a bending range extending in a bent manner, and a predetermined portion is coaxially connected to the intake system side portion at a joining point between the intake system side portion and the pressure sensor side portion in the bending range. A length of closed conduit is provided.

In this way, when the intake pipe pressure is introduced into the diaphragm of the pressure sensor, and when the particles move back and forth as foreign objects in the intake pipe pressure passage due to the pulsation of the intake pipe pressure, the particles are moved by inertia into the closed pipe passage. It collides with the closed part and becomes sticky. Near the closed part, the flow of gas that collides with the closed part causes a reverse flow, which reduces the gas flow velocity.As a result, particles adhering to the closed part are affected by the high-velocity airflow. Particles are prevented from being dispersed from the closed part, and particles once attached to the closed part can be reliably captured by the closed part. Therefore, particles are prevented from being introduced as foreign matter to the diaphragm of the pressure sensor, and foreign matter is prevented from adhering to the diaphragm and causing fluctuations in the output of the pressure sensor.

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the structure of a pressure-sensitive diaphragm 1 of an IC pressure sensor. A substrate crystal 2 of Si (silicon) is hollowed out by etching to a diameter of about 3 mm on the back side to form a predetermined hole 3 to form a thin diaphragm, and on the front side a diffusion lead portion 4 is formed by diffusion of impurities. A sensing part (gauge) 5 is formed in the center of the diffusion lead part 4, and the diffusion lead part 4 is made of Al (aluminum) at the peripheral end.
It is connected to an electrode 6 and further covered with a low melting point glass 7. The substrate crystal 2 is strained in relation to the pressure, and this strain is detected as a resistance change in the sensing section 5.

In FIG. 2, the IC-based pressure sensor 10 includes a pressure-sensitive diaphragm 1, a pedestal 12 on which the pressure-sensitive diaphragm 1 is mounted and which partitions a predetermined pressure chamber 11, an inlet pipe 13 communicating with the pressure chamber 11, and a pressure-sensitive diaphragm 1. 1 and the pedestal 12 from the outside to form a vacuum chamber 1.
4 is provided. The rubber tube 19 is connected at one end to an intake branch pipe (not shown), and a T-shaped tube 20 is provided between the rubber tube 19 and the inlet tube 13 of the IC pressure sensor 10. T-shaped tube 2
0 has a straight part 21 and a branch part 22 that branches vertically upward from approximately the center in the axial direction of the straight part 21, and the straight part 21 is connected to the rubber tube 19 at one end 23, and the other end 24. It was closed in
The branch part 22 is connected to the inlet pipe 13, and the branch part 22
An O-ring 25 for sealing is installed between the and the inlet pipe 13.
is provided. The T-shaped pipe 20 forms a bending range where the intake pipe pressure passage bends and extends, and a branch part 2 serves as an IC pressure sensor side portion in the bending range.
The portions of the straight portion 21 divided by 2 are coaxially connected to the intake system side portion 26 at the intake system side portion 26 in the bending range, and at the connection point between the intake system side portion 26 and the branch portion 22, respectively. predetermined length l
This becomes a closed pipe line 27.

Intake pipe pressure is determined by rubber pipe 1 as an intake pipe pressure passage.
9 and a T-shaped pipe to the pressure-sensitive diaphragm 1 of the IC pressure sensor. oil, gasoline,
Fine particles as foreign substances such as exhaust gas pass through the filter of the intake pipe pressure takeout port and enter the rubber pipe 19.
However, when passing through the T-shaped pipe 20 as a bending range, it cannot turn from the intake system side part 26 to the branch part 22 due to inertia, and the closed end pipe 27 remains as it is.
It advances to collide with the wall of the other closed end 24 and adheres due to viscosity. In the vicinity of the wall surface of the closed other end 24, which is the closed portion of the T-shaped pipe 20, the flow of gas that collides with the wall surface causes a reverse flow, so that the flow velocity of the gas decreases. The fine particles adhering to the wall surface are prevented from being dispersed from the wall surface by the high-velocity airflow, and the fine particles once adhering to the wall surface of the other closed end 24 can be almost reliably captured by the wall surface. This prevents fine particles that have entered the T-shaped pipe 20 from entering the branch pipe 22. Further, when the fine particles reciprocate within the straight portion 21 of the T-shaped pipe 20 due to the pulsation of the intake pipe pressure, the fine particles collide with the wall of the other closed end 24 and adhere thereto. In this case as well, the other end 24 is closed.
Since the flow velocity of the gas near the wall surface is low as described above, the fine particles once attached to the wall surface of the other closed end 24 can almost certainly be captured by the wall surface. Therefore, adhesion of foreign matter to the pressure sensitive diaphragm 1 is prevented. The material of the wall of the other closed end 24 has a surface roughness and material selected to improve the capture of particulates,
For example, a sintered metal material with a large surface area is preferred.

As described above, according to the present invention, the intake pipe pressure passage that guides the intake pressure to the diaphragm of the pressure sensor has a bending range that extends in a bent manner, and the closing pipe line is connected to this bending range. Fine particles as foreign matter that have entered the closed pipe line due to pressure introduction or pulsation of the intake pipe pressure are captured by the closed part of the closed pipe line, and are prevented from entering or adhering to the diaphragm of the pressure sensor.

[Brief explanation of the drawing]

FIG. 1 is a sectional view illustrating a pressure-sensitive diaphragm of an IC-based pressure sensor, and FIG. 2 is a sectional view illustrating an embodiment of the present invention. 1... Pressure sensitive diaphragm, 10... IC pressure sensor, 20... T-shaped pipe, 22... Branch, 26
...Intake system side part, 27...Closed pipe line.

Claims (1)

[Scope of utility model claims] In an intake pipe pressure detection device that guides intake pipe pressure to a diaphragm of a pressure sensor via an intake pipe pressure passage and obtains an electrical signal related to the intake pipe pressure as an output of the pressure sensor, the intake pipe pressure passage extends in a bent manner. It has a bending range, and is characterized in that a closed pipe line of a predetermined length is provided coaxially to the intake system side part at the joining point of the intake system side part and the pressure sensor side part in the bending range. Intake pipe pressure detection device.