JPH0443780Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an improvement in an air flow meter device that is provided in an engine intake system and measures the amount of air taken into the combustion chamber of the engine.

(Prior Art) In an engine in which the amount of fuel supplied is controlled in accordance with the amount of air taken into a combustion chamber, an air flow meter device for detecting the amount of intake air is provided in the intake system. This air flow meter is often used with a butterfly valve type measuring plate, such as the one shown in Japanese Utility Model Application Publication No. 59-8117. A potentiometer that supports the plate so as to be swingable and electrically detects the amount of rotation of the measuring shaft, which is the center axis of the plate's swing (in the above publication, the amount of light received from the light emitting diode and the projection light projected from the diode) The measuring plate swings according to the air flow rate passing through the casing, and the air flow rate can be determined from the swing amount of the plate or the rotating amount of the measuring shaft. It was designed to be measured.

However, this air flow meter device is generally installed downstream of the air cleaner in the intake system of the engine, but in an automobile engine,
For example, water splashed up when passing through a puddle on the road may flow from the air cleaner into the casing of the air flow meter device. Especially if the air flow meter device is installed at a low location, this water may flow into the casing of the air flow meter device. will accumulate in the casing of the air flow meter device. When water accumulates inside the casing, this water enters the potentiometer section of the air flow meter, causing rust on the components of the potentiometer, resulting in malfunctions, disconnections in electrical circuits, etc. This causes problems. Note that the potentiometer is usually installed in the upper part of the casing, but even in this case, water that accumulates inside the casing due to pressure fluctuations or capillary action passes through the bearing part of the measuring shaft. This causes the particles to enter the potentiometer section and cause the above-mentioned problems.

(Purpose of the invention) The present invention is an air flow meter device installed in the intake system of an engine to measure the amount of intake air. This is to prevent water from entering the potentiometer by reliably removing the water that accumulates inside the casing, thereby preventing malfunctions due to rust in the potentiometer parts and damage to the electrical circuit. The purpose is to prevent wire breakage, etc.

(Structure of the invention) That is, the air flow meter device according to the invention has the following features:
A measuring plate is swingably supported within the casing via a measuring shaft, and a potentiometer is provided at the top of the casing to electrically detect the amount of rotation of the measuring shaft. In a configuration in which the measuring shafts are orthogonal to each other and the potentiometer is located at the top,
forming a concave water reservoir below the measuring shaft at the bottom of the casing;
A drain hole is provided in the water reservoir, and a drain valve is provided to open and close the drain hole. The drain valve is configured to open when the engine is stopped or when fuel supply is stopped, such as when the engine is in operation.

According to such a configuration, water flowing into the casing of the air flow meter device from the air cleaner side accumulates in the water reservoir provided at the bottom of the casing. When the drain valve is opened, this water is discharged to the outside from the drain hole of the water reservoir, thereby preventing it from entering the potentiometer section in the upper part of the casing. In this case, the water reservoir is provided below the measuring shaft, that is, below the center of swing of the measuring plate attached to the shaft, and away from the wing portion of the plate that receives the air flow. Therefore, the air flow never passes through the water reservoir without acting on the wing portion of the plate, and therefore the accuracy of measuring the air flow rate does not deteriorate. In addition, since the drain valve is opened when fuel supply is stopped and measurement of air flow rate is not required, there is no problem even if some air leaks from the drain hole when the drain valve is opened. .

(Effects of the invention) As described above, according to the invention, in the air flow meter device installed in the intake system of an engine and measuring the amount of air taken into the combustion chamber, there is no problem such as a decrease in the measurement accuracy of the device. This makes it possible to reliably drain water that has flowed into the casing.
Water is prevented from entering the potentiometer section provided in the device. As a result, rusting of the components of the potentiometer and associated problems such as malfunctions and disconnections can be prevented.

(Example) Examples of the present invention will be described below.

First, the intake system 2 of the engine 1 equipped with the air flow meter device according to the present embodiment will be described with reference to FIG. 1. The intake system 2 includes an air intake duct 3 whose upstream end is an air intake port 3a; An air cleaner 4 connected to the downstream end of the duct 3, a main intake passage 6 leading from the air cleaner 4 to the surge tank 5, and an intake branch passage 7 branching from the surge tank 5 and leading to each combustion chamber of the engine 1. It is configured. A throttle valve 8 is provided on the upstream side of the surge tank 5 in the main intake passage 6.
Each intake branch passage 7 is provided with a fuel injection nozzle (not shown), and an air flow meter device 10 is provided downstream of the air cleaner 4 in the main intake passage 6.

Next, the configuration of this air flow meter device 10 will be explained. As shown in FIG.
1b, and the casing 1
A measuring plate 1 in which a wing portion 12a is arranged between the inlet and outlet 11a, 11b in the measuring plate 1.
2, a measuring shaft 13 extending in the vertical direction that swingably supports the plate 12 on a bearing boss 11c provided on the casing 11, and a rotation amount of the measuring shaft 13 provided on the upper part of the casing 11. and a potentiometer 14 that electrically detects. Here, the measuring plate 12 and the measuring shaft 13 are fixed, and therefore the potentiometer 14 detects the amount of rocking of the measuring plate 12. In addition, since the wing portion 12a of the measuring plate 12 receives the airflow passing between the inlet and the outlet 11a, 11b of the casing 11 and swings according to the flow rate, this air flow rate affects the measuring shaft 13. It will be measured by potentiometer 14 via . Although not shown, the measuring plate 12 is provided with an auxiliary wing section that is substantially orthogonal to the wing section 12a.

However, a concave water reservoir 1 is located below the measuring shaft 13 on the bottom plate 15 of the casing 11, that is, below the boss portion 12b provided at the pivoting center of the measuring plate 12.
5a is formed, and this water pool portion 15
A drain pipe 16 is connected to a drain hole 15b opened in the bottom surface of a, and a drain valve 17 is installed in the pipe 16. The drain valve 17 is constituted by, for example, a solenoid valve.
When engine 1 is stopped and the engine 1
When the engine is decelerating and the fuel supply is stopped, the engine stop detection means A or the deceleration detection means B
The valve is opened in response to a signal from the

In this embodiment, the lower surface of the boss portion 12b of the measuring plate 12 is recessed upward, and the peripheral wall 12d of the recessed portion 12c surrounds the upper portion of the water reservoir portion 15a. Due to the provision of the recessed portion 12c, the lower end position of the measuring shaft 13 fitted into the boss portion 12b is located at a position considerably higher than the casing bottom plate 15.

According to the above configuration, if water flows into the intake system 2 from the intake port 3a of the air intake duct 3 at the upstream end of the intake system 2 when the vehicle runs over a puddle of water on the road surface, etc. Water flows into the casing 11 of the air flow meter device 10 through the air cleaner 4, and since a concave water pool 15a is formed in the bottom plate 15 of the casing 11, the water flows into this water pool. 15a
It will accumulate inside. When the fuel supply is stopped, such as when the engine 1 is stopped or decelerated, the drain valve 17 is opened when there is no need to measure the amount of intake air into the fuel chamber. The water is discharged to the outside from the drain hole 15b of the water reservoir 15a through the drain pipe 16. As a result, the water accumulated inside the casing 11 passes through the bearing part of the measuring shaft 13 and reaches the potentiometer 14 at the upper part of the casing 11.
This prevents rust from forming in each component of the potentiometer 14, as well as malfunctions and disconnections caused by this. In this case, since the boss portion 12b of the measuring plate 12 located above the water reservoir portion 15a is recessed from the lower end surface and the lower end position of the measuring shaft 13 is raised, the lower end position of the measuring shaft 13 is raised. Even if water overflows the reservoir 15a and accumulates, the water level will not reach the lower end of the measuring shaft 13. Therefore, even in such a case, the water will flow through the bearing of the measuring shaft 13 and reach the potentiometer 14. This prevents water from entering the storage compartment. Further, the water reservoir portion 15a is provided below the boss member 12b of the measuring plate 12, that is, at a position away from the wing portion 12a that receives the airflow of the plate 12, and
Since the boss portion 12b is surrounded by the recess peripheral wall 12d, the casing 11
The air flowing from the inlet 11a to the outlet 11b does not pass through the water reservoir 15a, but always acts on the wing 12a of the measuring plate 12. Therefore, the measurement accuracy of the air flow rate does not deteriorate due to the provision of the water reservoir portion 15a. Furthermore, since the drain valve 17 that communicates the water reservoir portion 15a with the outside is opened when there is no need to measure the air flow rate, even if some air leaks to the outside when the drain valve 17 is opened, the This eliminates problems such as flow rate measurement errors and resulting errors in the amount of fuel supplied.

In the above embodiment, the case 18 housing the potentiometer 14 is provided with an inlet 18a and an outlet 18b for ventilation air, and a ventilator is provided between the inlet 18a and the air cleaner 4, and between the outlet 18b and the ventilating air. A ventilation air introduction pipe 19 and a suction pipe 20 are connected to the intake branch passage 7 (which may be the surge tank 5), respectively, and the suction pipe 20 is configured with, for example, a solenoid valve. A ventilation valve 21 is installed that opens in response to a signal from deceleration detection means C (which may also be used as deceleration detection means B for opening the drain valve 17) when the engine 1 is decelerating. According to this configuration, when the ventilation valve 21 is opened, the negative pressure in the intake branch passage 7 causes air to flow from the air cleaner 4 through the case 18 of the potentiometer 14 to the branch passage 7. A flow of fresh air will be generated, and this air flow will discharge the water vapor filling the case 18, and even if water has entered the case 18, this water will not be vaporized. It will be discharged. Thereby, rusting of each part of the potentiometer 14 can be more reliably prevented.

Incidentally, when the ventilation valve 21 is opened, air flow whose flow rate is not measured by the air flow meter device 10 will occur, but the valve 21 is opened during deceleration operation of the engine 1 when it is not necessary to measure the air flow rate. Therefore, problems due to measurement errors will not occur.

[Brief explanation of the drawing]

FIG. 1 is an intake system diagram of an engine equipped with an air flow meter device according to the present invention, and FIG. 2 is a longitudinal sectional view of the air flow meter device showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Engine, 10...Air flow meter device, 11...Casing, 12...Measure ring plate, 13...Measure ring shaft, 14
... Potentiometer, 15a ... Water reservoir part, 1
5b...Drain hole, 17...Drain valve.

Claims (1)

[Scope of utility model registration request] A measuring plate is supported in a casing via a measuring shaft and swings according to the flow rate of air passing through the casing, and a measuring shaft is provided on the upper part of the casing to control the amount of swing of the measuring ring plate. an air flow meter device that measures the amount of air supplied to the engine, the air flow meter device having a potentiometer that electrically detects the amount of air supplied to the engine; and a potentiometer is provided at the top, a concave water reservoir is formed below the measuring shaft at the bottom of the casing, and a drain hole provided in the water reservoir is provided. An air flow meter device comprising a drain valve that is opened when fuel supply to an engine is stopped.