JPH0443794Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an intake pipe pressure detection device that detects the intake pipe pressure of an engine using a pressure sensor.

[Conventional technology]

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 for generating 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 using a rubber pipe, etc.
Particles contained in oil, gasoline, and exhaust gas are removed by a filter made of metal, nonwoven fabric, etc., provided at the intake pipe pressure outlet port.

[Problem that the invention attempts to solve]

However, these filters are manufactured using IC pressure sensors, that is, ICs manufactured using IC technology, 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 diaphragm (2 to 3 mm square) of a pressure sensor, and to avoid delays in pressure propagation. Only large particles larger than 10 μm can be removed. Therefore, I.C.
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 passes through the filter, which is an impediment to the adoption of IC-based pressure sensors. It is becoming.

In view of the above points, it is an object of the present invention 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.

[Means for solving problems]

Therefore, in the present invention, the intake pipe pressure detection device guides the intake pipe pressure to the pressure sensor through the intake pipe pressure passage connected to the intake pipe of the internal combustion engine, and obtains an electrical signal related to the intake pipe pressure as the output of the pressure sensor. , connected to an intermediate portion of an intake pipe pressure passage leading from the intake pipe to the pressure sensor, and connected in a downward direction with respect to the intake pipe pressure passage, in a vertically upward direction towards the pressure sensor, and in an intake system of the intake pressure passage. Branch pipes branching into the intake pipe pressure passages in a coaxial direction with respect to the side portion, and piping directly connecting the passage branched in the downward direction and the passage branched in the coaxial direction are provided. It is characterized by

[Effect]

According to the present invention, when the intake pipe pressure is introduced to the diaphragm of the pressure sensor, the foreign matter such as oil or gasoline that has entered the intake pipe pressure passage due to the pulsation of the intake pipe pressure is reduced by the intake pipe pressure. The pulsations travel along the intake pipe pressure passage wall to the pressure sensor. However, most of this foreign material flows into a downwardly branched passage provided at an intermediate location.
The remaining foreign matter continues straight and flows into the coaxially branched passage. Foreign matter that has flowed into the downwardly branched passage and the coaxially branched passage flows into the piping that directly connects them.

Therefore, foreign matter is prevented from being introduced to the diaphragm of the pressure sensor, and foreign matter is prevented from adhering to the diaphragm and causing output fluctuations of the pressure sensor.

〔Example〕

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

FIG. 2 shows the structure of the pressure-sensitive diaphragm 1 of the IC-based 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 sensitive part (cage) 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. 1, reference numeral 10 denotes an IC-based pressure sensor including the pressure-sensitive diaphragm 1 shown in FIG. A rubber pipe 29, which is also connected to an intake pipe (not shown), is connected to a passage 45 provided in the horizontal direction of the cross pipe 41. The other two passages 46 and 47 provided in the cross tube 41 are connected to the rubber tube 43.
are directly connected to each other.

According to this example, the intake pressure guided by the rubber tube 29 passes from a passage 45 provided in the horizontal direction of the cross tube 41 to another passage 44 provided vertically upward, and then from the rubber tube 42 to the pressure sensor 10. guided by. Foreign substances such as oil and gasoline gradually move toward the pressure sensor along the wall of the rubber tube 29 due to intake pressure pulsations. Horizontal passage 4 of cross tube 41
Most of the foreign matter that has reached No. 5 falls from the passage 45 into a passage 46 provided vertically below, passes through the passage 46, reaches the rubber tube 43, and accumulates at the bottom b of the rubber tube 43.

Further, the remaining foreign matter advances from the passage 45 of the cross tube 41 to another passage 47 provided horizontally and coaxially, further enters the rubber tube 43 having a downwardly arcuate shape, and accumulates at the bottom b of the rubber tube 43.

As a result, foreign matter that has entered the rubber tube 29 due to pressure pulsations is always removed from the rubber tube 49, which has a downward arc shape.
This prevents foreign matter from entering the pressure sensitive diaphragm of the pressure sensor 10.

[Effect of idea]

As described above, according to the present invention, by the action of the first and second branch passages provided in the middle of the intake pipe pressure passage, foreign matter entering the passage is removed from the piping connected to both branch passages. This can effectively prevent foreign matter from adhering to the diaphragm of the pressure sensor.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the device of the present invention;
FIG. 2 is a sectional view showing the pressure sensitive diaphragm of the pressure sensor. 10...Pressure sensor, 20, 24...T-shaped pipe,
29, 30, 43...Rubber tube, 41...Cross tube.

Claims (1)

[Claim for Utility Model Registration] An intake pipe that guides intake pipe pressure to a pressure sensor through an intake pipe pressure passage connected to the intake pipe of an internal combustion engine, and obtains an electrical signal related to the intake pipe pressure as the output of the pressure sensor. In the pressure detection device, the pressure sensor is connected to a midway portion of an intake pipe pressure passage leading from the intake pipe to the pressure sensor, and is connected in a downward direction with respect to the intake pipe pressure passage, in a vertically upward direction toward the pressure sensor, and in a vertically upward direction toward the pressure sensor. a branch pipe that branches the intake pipe pressure passage in a coaxial direction with respect to an intake system side portion of the intake system, and a pipe that directly connects the passage branched in the downward direction and the passage branched in the coaxial direction. An intake pipe pressure detection device characterized by being provided.