JPS5914174B2 - Internal combustion engine intake air amount measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake air amount measuring device for an internal combustion engine that utilizes a Karman vortex generated by a vortex generating column provided in an intake air passage.

The fuel injection system of an internal combustion engine requires momentary measurement of the amount of intake air.

In addition, the so-called vortex flow meter, which measures the air flow rate by arranging a vortex generating column in the air passage and measuring the Karman vortices generated on the downstream side, has low pressure loss, a wide measurement range, and vibration resistance. It has the advantage of being highly flexible, making it suitable as a flow meter for the intake air of internal combustion engines. By the way, the intake air of an internal combustion engine does not flow uniformly but pulsates. In particular, when the throttle valve is close to fully open, the intake manifold negative pressure is as small as approximately 50m1V or less.
Also, there is significant pulsation during low speed rotation. The vortex flow meter has the disadvantage that when the flow velocity is very small, that is, when the Reynolds number, whose representative length is the width of the vortex generation column, is less than 500, the vortex generation 15 becomes unstable and causes errors. . Therefore, in order to use a vortex flow meter to measure the intake air amount of an internal combustion engine, it is necessary to suppress the pulsation of the intake air and maintain the Reynolds number so that it does not fall below 500 even when the pulsation slows down the flow velocity. ■0 Required to do so. In response to the above-mentioned requirements, the present invention provides an intake air amount measuring device that suppresses the pulsation of intake air of an internal combustion engine and maintains the lower limit of its flow velocity within the effective measurement range of a vortex flow meter. There are 25 items aimed at.

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

In FIG. 1 showing one embodiment, reference numeral 1 denotes an intake air passage that guides intake air to an internal combustion engine (not shown), and a throttle 90 valve 2 for controlling the amount of intake air is provided in this passage 1. Reference numeral 3 denotes a vortex generating column provided upstream of the throttle valve 2 in the intake air passage 1, and this vortex generating column 3 is installed so as to be substantially perpendicular to the flow direction of the intake air.

4 is an ultrasonic oscillator that emits ultrasonic waves to the Cull-35 Mann vortex of intake air generated downstream of the vortex generating column 3;
This oscillator 4 is driven by an ultrasonic generator 4a.

Reference numeral 5 denotes an ultrasonic receiver that receives the ultrasonic waves from the ultrasonic oscillator 4 modulated by the Karman vortices, and the output of this receiver 5 is demodulated by the processing circuit 5a to determine the frequency. One voltage is converted to obtain an electrical output corresponding to the number (frequency) of Karman vortices, and these constitute a vortex detector that detects the number of Karman vortices.

Reference numeral 6 denotes a rotary impeller provided downstream of the vortex generating column 1 and upstream of the throttle valve 2 in the intake air passage 1, and the rotary impeller 6 is rotatable about an axis provided parallel to the intake air flow. ing.

Next, the operation of the intake air amount measuring device configured as above will be explained.

The air sucked into the intake air passage 1 creates a number of Karman vortices corresponding to the air flow rate on the downstream side of the vortex generation column 3, passes through them while rotating the rotary impeller 6, and then passes through the throttle valve 2. It is drawn into the combustion chamber through the intake valve of the internal combustion engine.

The vortex generated by the vortex generating column 3 mixes a frequency signal corresponding to the vortex into the ultrasonic wave from the ultrasonic oscillator 4, which is received by the receiver 5 and sent to the processing circuit 5a. It is then converted into a voltage output corresponding to the air flow rate. now,
When the throttle valve is close to fully open and the pulsation of the intake air becomes intense, that is, when the flow velocity of the intake air begins to increase or decrease, the rotation of the rotary impeller 6 becomes similar to that of a windmill when the flow velocity is about to increase. It accelerates, but due to inertia, it cannot accelerate suddenly and accumulates energy. Next, when the flow rate is about to slow down, it releases the previously accumulated energy due to inertia and continues to rotate, acting as a proa to increase the flow rate. That is, the rotor 6 is
When the flow velocity pulsation of the intake air is accelerated, it acts as a brake, and when the pulsation is decelerated, it acts as an acceleration, and the pulsation is suppressed and leveled out as a whole. Further, FIG. 2 shows another embodiment, in which a communication hole 8 provided in the peripheral wall between the rotary impeller 6 of the intake air passage 1 and the throttle valve 2 allows
An intake air passage 1 communicates with an air chamber 7. With the above-described structure, the action of the rotary impeller 6 to suppress flow velocity pulsations of the intake air is promoted, making it even more effective. In other words, when the flow velocity of the pulsating intake air becomes faster, it is when a strong suction force acts in the direction of the combustion chamber of the internal combustion engine, so the air in the air chamber 7 flows from the communication hole 8 to the intake air passage 1.
When the flow velocity decreases, the amount of air flowing into the combustion chamber decreases, so the rotating impeller 6 acts as a propeller and the accelerating air is sucked into the combustion chamber of the internal combustion engine. 8 into the air chamber 7, the load on the rotor wheel 6 is reduced, and the air can be easily accelerated.
Note that in the embodiment shown in FIG. 2, the configuration and operation other than those described above are the same as those shown in FIG. 1, so explanations thereof will be omitted. FIG. 3 shows yet another embodiment, in which a driving electric motor 9 is connected to the rotary impeller 6, and this electric motor 9 is energized from a power source 11 via a switch 10. There is. The switch 10 is engaged with the throttle valve 2 by an interlocking mechanism 12, and the throttle valve 2
It is closed only when fully open and in the vicinity. In the embodiment shown in FIG. 3, the configuration other than those described above is the same as that shown in FIG. 1, so a description thereof will be omitted. Next, the third
To explain the operation of the embodiment shown in the figure, the intake air passage 1
As in the embodiment shown in FIG. 1, the pulsation of the intake air inside is suppressed by the inertia of the rotary impeller 6, and the amount of air is measured without error by the vortex generating column 3 and the vortex detector. It is.

When the rotary impeller 6 rotates, the velocity energy of the intake air is lost by the friction loss of its bearing, resulting in a pressure loss passing through the rotary impeller, so when operating with the throttle valve 2 fully open or close to it. The intake air amount of the engine decreases, and the output of the internal combustion engine decreases, but this phenomenon is caused by
This can be avoided by energizing at 1. That is, the switch 10 is closed in conjunction with the throttle valve 2 by the interlocking mechanism 12, the electric motor 9 is energized from the power source 11, and its drive transfers energy equivalent to the friction loss of the bearing to the rotor 6. is supplied and the rotary impeller 6 is rotated, so that no pressure loss occurs in the impeller 6. Note that the effect of the energy supply described above occurs only when the throttle valve is fully open or when operating near it, so even if a boost switch is used that operates the motor switch when the intake manifold negative pressure is low, , an objective similar to that of FIG. 3 is achieved.

Further, as long as some energy loss is allowed, there is no problem even if the rotor is driven all the time, so the interlocking mechanism 12 and the boost switch can be omitted.

Furthermore, since the suppression of intake air pulsation, which is the object of this invention, is necessary only when the throttle valve is fully open or when the intake manifold negative pressure in the vicinity is small, restraint can be used instead of the rotor drive device. The device may be used to release the restraint of the rotary impeller and rotate the rotary impeller only when necessary as described above by detecting the opening of the throttle valve or the negative pressure of the intake manifold. This will reduce wear on the bearings of the rotor and can be expected to extend their lifespan.

In this invention, the number of rotary impellers is not limited to one, and a plurality of rotary impellers may be provided.

As explained above, according to the present invention, the pulsation of the intake air of an internal combustion engine is suppressed, and the lower limit of the flow velocity can be maintained within the effective measurement range of the vortex flowmeter. It is possible to provide an engine intake air amount measuring device and eliminate measurement errors.

[Brief explanation of the drawing]

FIG. 1 is a side sectional configuration diagram showing one embodiment of the present invention, and FIG.
The figure is a side sectional configuration diagram showing another embodiment, and FIG. 3 is a side sectional configuration diagram showing still another embodiment. 1... Intake air passage, 2... Throttle valve, 3... Vortex generating column, 4... Ultrasonic oscillator, 5...・Receiver, 6...Rotor wheel, 7...Air chamber, 8...Communication hole, 9
...... Drive motor, 10... Switch, 11... Power supply, 12... Interlocking mechanism.

Claims (1)

[Claims] 1. A vortex generating column arranged in an intake air passage of an internal combustion engine so as to be substantially orthogonal to the flow direction of the intake air, and a vortex of the intake air generated by the vortex generating column. 1. An intake air amount measuring device for an internal combustion engine, comprising: a vortex detector for detecting the number of vortices; and one or more rotary impellers installed downstream of the vortex generating column. 2. The intake air amount measuring device for an internal combustion engine according to claim 1, wherein the rotary impeller has a drive device thereof. 3. The intake air amount measuring device for an internal combustion engine according to claim 2, wherein the drive device responds to the opening degree of a throttle valve or the negative pressure of an intake manifold. 4. An intake air amount measuring device for an internal combustion engine according to claim 1, wherein the rotor has a restraining device that is opened in response to the opening of a throttle valve or negative pressure in an intake manifold.