JPS5920645Y2 - Intake air amount detection device for internal combustion engines - Google Patents

Description

[Detailed Description of the Invention] The present invention mainly relates to an intake air amount detection device for an internal combustion engine that detects the intake air amount of an internal combustion engine equipped with an electronically controlled fuel injection device.

Maintaining the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine at a certain constant air-fuel ratio is an extremely effective means for cleaning exhaust gas discharged from the engine.

Therefore, it is necessary to accurately detect the engine intake air amount and supply the engine with the amount of fuel corresponding to this air amount. However, in conventional detection devices of this type, the engine speed and intake negative pressure or the engine rotation A method was used to indirectly detect the volumetric intake air amount from the number and throttle valve opening.

In this conventional method, the amount of intake air from the intake pipe is indirectly measured, so variations in engine production,
Measurement errors become large due to the effects of engine deterioration, poor adjustment of the engine's intake valve and exhaust valve gaps, aging of the air cleaner, etc.Also, since measurement is performed using volume flow, absolute pressure correction must be performed, which may cause problems with the equipment. It has the disadvantage of being complicated and increasing cost.

The present invention is an attempt to solve the above-mentioned problems.A branch pipe having two passages is provided in the intake pipe of the engine, and a first and second temperature detection element is provided in each passage of the branch pipe. Furthermore, an electric heater is installed upstream of the first temperature detection element, and the heat generated by the electric heater generates a certain temperature difference between the two passages of the branch pipe, and this temperature difference is applied to the first and second passages. When the voltage applied to the electric heater, that is, the amount of heat generated, is controlled to keep this temperature difference constant, this voltage becomes a value related to the intake air amount, and the voltage is expressed as a weight flow rate of the intake air amount. This is done so that a signal corresponding to the current condition can be obtained.

In this way, the present invention accurately measures the amount of intake air that directly passes through the intake pipe in terms of weight flow rate, but when using this device in an actual vehicle, it is difficult to measure engine vibrations and vehicle vibrations that occur during vehicle operation. Sufficient durability is also required.

Therefore, in the present invention, a buffer protection tube is provided in the passage of the branch pipe, and the electric heater and the temperature detection element are supported through the buffer protection tube.

Therefore, it is an object of the present invention to provide an intake air amount detection device that can prevent the electric heater and temperature detection element from being damaged or disconnected due to vibrations, etc., and can serve as a heat insulating layer to ensure proper operation at all times. It is a purpose.

An embodiment of the device of the present invention shown in the drawings will be described below.

1 and 2, 1 is an intake pipe of an internal combustion engine (not shown), 2 is a throttle valve provided in the intake pipe 1, and 4 is a throttle valve provided in the intake pipe 1.
1 shows a rectifying section in which the inlet section of the intake pipe 1 is processed into a bell mouth shape.

Reference numeral 3 denotes an intake air amount detecting device according to the present invention, which is installed in the intake pipe 1 immediately downstream of the rectifying section 4.

Reference numeral 5 denotes a gasket which is interposed between the device 3 of the present invention and the intake pipe 1, and this gasket 5 is made of a soft material such as rubber and has the function of absorbing vibrations.

6 is a branch pipe provided in the intake pipe 1 and has two passages 6a,
6b and is made of a heat insulating material such as glass wool.

10 is a first temperature detection element provided in one passage 6a in the branch pipe 6, 11 is a second temperature detection element provided in the other passage 6b of the branch pipe 6, and both temperature detection elements 10 ．．
No. 11 has the same resistance temperature characteristics.

In this embodiment, a platinum resistance wire having a positive temperature-resistance coefficient is used as the temperature detection element.

Reference numeral 12 denotes an electric heater provided upstream of the temperature detection element 10, and a platinum resistance wire is used in this embodiment.

Fig. 3 a, l) shows the structure of the first temperature detection element, and as explained below in Fig. 3 a, l), 10 a
is an annular insulating substrate made of glass epoxy, paper epoxy, ceramic, etc.

10b is a platinum resistance wire stretched in a grid pattern on the insulating substrate 10a, and IOC is an electrode bonded to the surface of the insulating substrate 10a, which is made of copper, gold, or silver.
Each platinum resistance wire 10b is connected in series.

10d is a lead wire connected to the electrodes at both ends.

Although not shown, the second temperature detection element 11 and the electric heater 12 also have a similar structure.

FIG. 4 is a longitudinal sectional view showing one passage 6a of the branch pipe 6.
The mounting state of the first temperature detection element 10 and the electric heater 12 is shown.

Here, a stepped portion is formed in the branch pipe 6, and a buffer protection tube 8 is fitted into this stepped portion.

This buffer protection tube 8 is made of a buffer material such as rubber or soft resin, and has the function of absorbing vibrations.

Then, inside this buffer protection tube 8, a first
The temperature detection element 10 and the electric heater 12 are connected to the branch pipe 6.
It is fixed by an annular plate 13.14 forming part of the.

Note that the passage 6b also has a similar structure.

Next, to explain the operation of the device of the present invention, a certain amount of air determined by the opening degree of the throttle valve 2 is taken in from an air cleaner (not shown), passes through the intake pipe 1, and passes through the intake pipe 1 (not shown). Inhaled into internal combustion engines.

At this time, since the intake air taken into the intake pipe 1 is rectified by the bellmouth-shaped rectifier 4, a certain proportion of the total intake air is always transferred into the branch pipe 6 having the two passages 6a and 6b. In one passage 6a of the branch pipe 6, due to heat generation from the electric heater 12, the intake air passing there reaches the first temperature detection device 1 with a certain temperature rise AT.
0 and is sucked into the internal combustion engine.

In the other passage 6b, intake air passes through the second temperature detection element 11 and is drawn into the internal combustion engine.

As a result, there is an electric heater 1 between both temperature detection elements 10 and 11.
Temperature difference related to the amount of intake air caused by heat generation in step 2 △
T occurs as a voltage change.

In this way, a voltage difference is obtained by the resistance change of the first and second temperature resistance elements 10.11 caused by this temperature difference ΔT, and this voltage difference is detected by the lead wire.

Here, since the temperature difference △T detected as a voltage difference changes depending on the amount of intake air, a control circuit (not shown) is used to keep this temperature difference △T constant. If you control the electric heater 1
The control voltage No. 2 has a value related to the amount of intake air, and thus a signal related to the amount of intake air is obtained.

Furthermore, as a result of being mounted on an actual vehicle, the device 3 of the present invention is subject to engine vibrations and vehicle vibrations.
．． 11 and the electric heater 12 are held in the passages 6a and 6br"Jl of the branch pipe 6 by the buffer protection tube 8, respectively, so they will not be damaged or disconnected due to vibration etc., and will always operate properly and prevent erroneous signals. This never occurs.

As explained above, in the present invention, by holding both temperature detection elements and the electric heater in the branch pipe with a buffer protection tube, both temperature detection elements and the electric heater are prevented from being damaged or disconnected due to vibrations of the engine or vehicle. It is possible to prevent this, and it is also thermally isolated, so that sufficient durability, proper operation and accuracy can be obtained, and the function of detecting the amount of intake air can be fully demonstrated.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram showing one embodiment of the device of the present invention;
The figure is an enlarged front view of the branch pipe shown in Fig. 1, and Fig. 3 is an enlarged front view of the branch pipe shown in Fig. 2.
The temperature detection element shown in the figure is shown in an enlarged scale, with Figure 3a being a front view thereof, Figure 3A being a longitudinal sectional view thereof, and Figure 4 being a longitudinal sectional view of the branch pipe shown in Figure 1. It is. 1... Intake pipe, 6... Branch pipe, 8...
...Buffer protection tube, 10...First temperature detection element, 11...Second temperature detection element, 12...
...Electric heater.

Claims (1)

[Scope of utility model registration request] A measurement tube provided in the intake pipe of an internal combustion engine, a plurality of substrates made of an insulating material, and a temperature-dependent resistor whose resistance value changes depending on the temperature supported by each substrate. A held intake air amount detection section,
An annular plate that is provided before and after the plurality of substrates, fixes the plurality of substrates in the front-back direction, and forms a part of the measurement tube, and between the plurality of substrates, the annular plate, and the measurement tube. An intake air amount detection device for an internal combustion engine, further comprising: a buffer protection layer made of a sheet of buffer material interposed in an annular shape so as to enclose the plurality of substrates and the annular plate.