JPH01113569A - Blinding detecting device for air cleaner for internal combustion engine - Google Patents

Abstract

PURPOSE:To accurately detect blinding by comparing blinding limit differential pressure according to the intake air quantity obtained from the absolute pressure on the upstream side of an air cleaner with a difference in pressure between the upstream and downstream sides of the main cleaner, and detecting blinding from the comparison result to give a warning. CONSTITUTION:Pressure introducing pipes 7a, 7b are respectively extended from the upstream and downstream sides of an air cleaner 5 and connected to a pressure detecting portion 1. The pressure detecting portion 1 comprises a pressure sensitive rubber 2 as a differential pressure detector, the peripheral edge of which is clamped by the inner peripheral wall of a housing 11 and a pressure sensitive rubber 3 as an absolute pressure detector disposed in a circular recess portion 21 formed at the central portion of an end surface of the pressure sensitive rubber, that confronts with an upstream negative pressure chamber 13. Output signals of the pressuresensitive rubbers 2, 3 are input to a blinding detecting circuit 4, and on setting a blinding limit differential pressure according to the intake air quantity obtained from an absolute pressure detected value, the limit differential pressure and a detected differential pressure are compared. When the limit differential pressure N smaller then the detected differential pressure, the occurrence of blinding is decided to operate warning means 9.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a clogging detection device for detecting clogging of an air cleaner for an internal combustion engine by a decrease in the pressure inside the intake pipe, and particularly to a clogging detection device that detects clogging of an air cleaner for an internal combustion engine by a decrease in pressure inside the intake pipe. The present invention relates to a clogging detection device that can accurately detect clogging without causing any damage.

[Prior Art] In an internal combustion engine such as a vehicle engine, an air cleaner is usually provided in the middle of the engine intake pipe to remove dust from the air being taken in and prevent wear of the piston and cylinder.

Conventionally, such a clogging detection device for an air cleaner for an internal combustion engine has generally utilized the fact that the negative pressure in the intake pipe increases as the clogging of the air cleaner element progresses.

For example, in the device disclosed in Japanese Utility Model Application Publication No. 60-72969,
Clogging is indicated by the amount of deformation of the pressure receiving diaphragm that receives negative pressure in the intake pipe. Further, Japanese Utility Model Publication No. 59-36688 discloses a device that issues a clogging alarm when the amount of deformation of a pressure-receiving bellows exceeds a predetermined value, and Japanese Utility Model Publication No. 62-57768 discloses a device that issues a clogging alarm when the amount of deformation of a pressure-receiving diaphragm exceeds a predetermined value. A clogging detection device is disclosed in which a piezoelectric rubber plate converts the signal into an electric signal and activates an alarm.

[Problems to be Solved by the Invention] Incidentally, the negative pressure in the engine intake pipe varies depending on the intake air amount of the engine, in addition to the clogging state of the air cleaner, and when the airflow resistance of the air cleaner element is constant, As the intake air amount of the engine increases, that is, the engine speed increases, the negative pressure in the intake pipe increases.

However, the conventional clogging detection device described above is a mechanism that issues an alarm when the negative pressure inside the intake pipe exceeds a certain set pressure, so differences in intake air amount are not taken into account, and clogging cannot be detected accurately. I can't say that there is. - For example, in Fig. 6, 11 indicates the flow rate-pressure curve downstream of a new air cleaner that is not clogged, and g2 indicates the flow rate-pressure curve downstream of the air cleaner that has been used to the limit of clogging. Clogging limit PA (L point)
If the flow rate is Ql smaller than QO, the alarm will not be activated until the clogging limit (N point) is exceeded and an increased resistance of ΔP occurs. This is the same even when taking into account the negative pressure in the pipe upstream of the air cleaner.If the set pressure is the difference between gl and ρ2 of 300 mmAq at the rated air flow rate QO, the flow ff1Q1 will exceed the clogging limit (N point) and reach 5 points. The alarm will not be activated until this point is reached, which will have a negative impact on fuel efficiency and engine output. Furthermore, if the intake air amount is larger than QO, a false alarm may occur before the clogging limit is reached.

In view of the above problems, the present invention aims to provide a clogging detection device for an air cleaner for an internal combustion engine that has a simple structure and can accurately detect clogging of the air cleaner without being affected by the amount of intake air. There are things you can do for yourself.

[Means for Solving the Problems] To explain the configuration of the present invention using the drawings, the clogging detection device detects the clogging in the intake pipe 6 for an internal combustion engine provided with the air cleaner 5 (FIG. 2).
A differential pressure detector 2 (Fig. 1) that detects the differential pressure between the upstream side and the downstream side of the air cleaner 5, an absolute pressure detector 3 that detects the absolute pressure on the upstream side of the air cleaner 5, and the pressure detected by this detector 3. a clogging limit differential pressure setting means R2 that determines the amount of intake air flowing through the intake pipe from the upstream absolute pressure detected and sets a clogging limit differential pressure corresponding to the amount of intake air; Comparing means C (Fig. 4) that compares the limit differential pressures and issues a clogging signal when the former becomes larger than the latter; and an alarm means 9 that is activated by the output of the comparing means C to warn of clogging of the air cleaner. (Fig. 4).

[Function] When the negative pressure in the intake pipe upstream and downstream of the air cleaner is introduced into the differential pressure detector 2, a signal corresponding to these differential pressures is generated from the differential pressure detector 2 and inputted to the comparison means C. Ru. On the other hand, when the absolute pressure upstream of the air cleaner is introduced into the absolute pressure detector 3, the clogging limit differential pressure setting means R2 sets a corresponding clogging limit differential pressure, and the signal is transmitted to the comparing means C
is input. Comparison means C compares the input differential pressure with the clogging limit differential pressure, and issues a clogging signal when the former is greater than the latter. When the clogging signal is issued, the alarm means 9 is activated to warn of clogging of the air cleaner.

[Effects of the Invention] According to the present invention, the absolute pressure upstream of the air cleaner is detected at the same time as the differential pressure upstream and downstream of the air cleaner, and the clogging limit differential pressure at which an alarm is issued is determined each time according to the absolute pressure. Since this change has been made, it is possible to eliminate the influence of the amount of intake air, and it is possible to accurately detect clogging of the air cleaner with a simple structure.

[Embodiment] In FIG. 2, an air cleaner 5 is provided in an intake pipe 6 leading to an internal combustion engine 8, and pressure introduction pipes 7a are connected from the intake pipe 6 to the upstream and downstream sides of the air cleaner 5, respectively.
, 7b extend to reach the pressure detection section 1. A clogging detection circuit 4 is connected to the pressure detection section 1, and the detection circuit 4 is connected to a clogging warning light 9 made of a light emitting diode.

Details of the pressure detection section 1 are shown in FIG. 1. The main body housing 11 of the detection unit 1 is a hollow cylinder.
Joint pipes 12a and 12b are formed protruding from the inner end surface to connect the pressure introduction pipes 7a and 7b, respectively. A disc-shaped pressure sensitive rubber 2 for detecting differential pressure is provided in the center of the housing 11 as a differential pressure detecting body with its peripheral edge sandwiched between the inner circumferential wall. The air cleaner 5 is divided into a negative pressure chamber 13 on the upstream side and a negative pressure chamber 14 on the downstream side.

The details of the pressure sensitive rubber 2 for differential pressure detection will be explained with reference to FIG. 3. The pressure sensitive rubber 2 is provided with four circular parts 21 at the center of its end face facing the negative pressure chamber 13 on the downstream side. 21 is provided with a pressure-sensitive rubber 3 for absolute pressure detection as an absolute pressure detector, which has approximately the same diameter as this.

The surface of the pressure sensitive rubber 3 except for the end face facing the negative pressure chamber 13 on the upstream side is held by a holding member 31 made of an insulating material. This is to prevent interference with the pressure sensitive rubber 3 for use.

Each of the above pressure sensitive rubbers 2.3 is a rubber whose resistance value changes linearly according to the applied pressure. The resistance changes depending on the contact area when the conductive rubber is displaced under pressure and comes into contact with the conductive plate. These include things whose values change.

Lead wires 22 and 32 extend from the pressure sensitive rubber 2 for differential pressure detection and the pressure sensitive rubber 3 for absolute pressure detection, respectively.
These outputs are input to the clogging detection circuit 4. The clogging detection circuit 4 includes a comparator circuit C as a comparison means.
A transistor T is provided which is activated by the comparator output and lights up a clogging warning light as an alarm means.

As shown in FIG. 4, resistors R1 and R2 are connected in series to the pressure sensitive rubber 2 for differential pressure detection and the pressure sensitive rubber 3 for absolute pressure detection, respectively. R1
, R2 constitute a bridge circuit. A method for adjusting the resistor R2 in the bridge circuit will be described below. In FIG. 5, when the rated air RQO of the internal combustion engine 8 is reached, the absolute pressure on the upstream side of the air cleaner 5 is detected by the pressure sensitive rubber 3 for absolute pressure detection, and the output voltage A (point A on the flow rate-pressure curve 91) is detected. get. On the other hand, when the air cleaner 5 has reached its clogging limit, the differential pressure between the upstream side and the downstream side of the air cleaner 5 at rated air HQO is detected by the differential pressure sensitive rubber 2, and the output voltage C (
0 point on the meteor-pressure curve g2) is obtained. Then, the resistor R2 as a clogging limit differential pressure setting means is adjusted so that the output voltage A of the pressure-sensitive rubber 3 for absolute pressure detection coincides with the output voltage C indicating the clogging limit. Thus, air cleaner 5
A pseudo-clogging limit curve fJ3 is obtained by changing the slope of 91 indicating the relationship between the absolute pressure on the upstream side and the intake air amount, and the comparator circuit C always includes the pressure-sensitive rubber 3 for absolute pressure detection and the resistor R2.
The divided voltage is input as a clogging limit differential pressure signal corresponding to the intake air amount at that time.

In FIG. 5, the flow rate-pressure curve ρ2 is an actually measured clogging limit curve of the air cleaner 5.

In the above configuration, when the internal combustion engine is operating, the negative pressure on the upstream and downstream sides of the air cleaner 5 of the intake pipe 6 is applied to the pressure introduction pipe 7a.
, 7b into the pressure detection unit housing 11,
Negative pressure is applied to both sides of the pressure sensitive rubber 2 for differential pressure detection. Then, the resistance of the pressure sensitive rubber 2 changes according to the difference in the applied negative pressure, and the output corresponding to this changes from the comparator circuit C.
to go into.

On the other hand, the absolute pressure on the upstream side of the air cleaner 5 is applied to the pressure sensitive rubber 3 for absolute pressure detection, the resistance changes, and a signal indicating the clogging limit at the absolute pressure is outputted and inputted to the comparator circuit C. Ru.

When the air cleaner 5 starts to be used, the output of the pressure sensitive rubber 2 for detecting the differential pressure is the flow rate-pressure curve, l! As indicated by the point above 4, as the clogging progresses, the slope of 14 increases and moves in the direction of the arrow in FIG. The above comparator circuit C is
When the output of the pressure sensitive rubber 2 becomes greater than the output of the pressure sensitive rubber 3 for absolute pressure detection, a "1" level output is generated, and when clogging progresses and exceeds the clogging limit. The comparator circuit C operates and the clogging warning light 9 lights up.

In this way, in the present invention, an absolute pressure detector made of pressure-sensitive rubber is provided, and the clogging limit differential pressure is set according to the output of the absolute pressure detector, and the differential pressure detector made of pressure-sensitive rubber is used for detection. Since clogging is detected by comparing the differential pressure obtained with the clogging limit differential pressure, the clogging limit can be accurately detected almost unaffected by the amount of intake air.

In the above embodiment, since the differential pressure detector and the absolute pressure detector are provided integrally, it is compact and easy to install. In addition, since clogging can be detected with a simple structure without requiring a complicated circuit, it is possible to reduce the size and weight.

In the above embodiment, the clogging detection circuit is provided separately from the pressure detection section, but the clogging detection circuit may be provided within the pressure detection section. Furthermore, the absolute pressure detector does not need to be integrated with the differential pressure detector, and may be provided anywhere as long as it is located at a position where the upstream absolute pressure can be detected.

Further, the differential pressure detector and the absolute pressure detector do not need to be made of pressure-sensitive rubber, and a conventional diaphragm type can also be used. In addition to the clogging warning light, a chime, a buzzer, etc. may be used as the warning means.

In the above embodiment, the setting of the clogging limit differential pressure, the comparison of this with the measured differential pressure, etc. were realized using a hardware circuit, but it is also possible to perform the processing using computer software.

[Brief explanation of the drawing]

1 to 5 show an embodiment of the clogging detection device of the present invention, FIG. 1 is an overall sectional view of the pressure detection section, and FIG. 2 is an internal combustion engine equipped with the clogging detection device of the present invention. A system diagram of the air cleaner, Fig. 3 is an exploded perspective view of the pressure detector, Fig. 4 is a circuit diagram of the clogging detection circuit, Fig. 5 is a diagram showing the operation of the clogging detection circuit, and Fig. 6 is a conventional FIG. 3 is a diagram showing the operation of the clogging detection device. 13.14...Negative pressure chamber (pressure chamber) 2...Pressure sensitive rubber for differential pressure detection (differential pressure detector) 3...Pressure sensitive rubber for absolute pressure detection (absolute pressure detector) 31...・Holding member 5...Air cleaner 6...Intake pipe for internal combustion engine 9...Clogged warning light (warning means) C...Comparator circuit (comparison means) R2...Resistance (clogging limit Differential pressure setting means) vJ1 diagram Figure 3

Claims (3)

[Claims] (1) In an intake pipe for an internal combustion engine equipped with an air cleaner, a differential pressure detector detects the differential pressure between the upstream side and the downstream side of the air cleaner, and an absolute pressure detector detects the absolute pressure upstream of the air cleaner. clogging limit differential pressure setting means for determining the amount of intake air flowing through the intake pipe from the upstream absolute pressure detected, and setting a clogging limit differential pressure corresponding to the amount of intake air; An internal combustion engine comprising a comparison means that compares differential pressures and issues a clogging signal when the former is greater than the latter, and an alarm means that is activated by the clogging signal of the comparison means to warn of clogging of the air cleaner. Air cleaner clogging detection device. (2) The differential pressure detector and the absolute pressure detector are made of pressure-sensitive rubber that deforms under pressure and changes its resistance, and the pressure-sensitive rubber for differential pressure detection is used for negative pressure on the upstream and downstream sides of the air cleaner. The pressure sensitive rubber for detecting absolute pressure is provided integrally with the pressure sensitive rubber for detecting differential pressure so as to face the pressure chamber for introducing negative pressure on the upstream side. , and the pressure-sensitive rubber for detecting absolute pressure is covered with a holding member made of an electrically insulating material that does not deform under pressure, except for the surface facing the pressure chamber into which the upstream negative pressure is introduced. The clogging detection device for an air cleaner for an internal combustion engine according to item 1. (3) The clogging limit differential pressure setting means has a resistor with a constant resistance value connected in series to the pressure sensitive rubber for absolute pressure detection, and uses these divided voltages as a clogging limit differential pressure signal. The output signal is output to a comparator constituting the comparison means, and the comparator is set to compare the output signal of the pressure-sensitive rubber for differential pressure detection with a clogging limit differential pressure signal and issue a clogging signal. A clogging detection device for an internal combustion engine air cleaner according to scope 2.