JP4986058B2 - Fuel filter replacement time determination device - Google Patents

Description

  The present invention relates to a fuel filter interposed in a fuel supply system of an internal combustion engine (for example, a diesel engine). More specifically, the present invention relates to a technique for determining when to replace a fuel filter.

The replacement timing when the fuel filter is replaced is determined based on the actual travel distance or the pressure loss in the fuel filter.
FIG. 7 shows the characteristics of the travel distance (horizontal axis) in the fuel filter of an automobile engine and the pressure loss in the fuel filter (difference between the pressure at the filter inlet and the pressure at the outlet: vertical axis).
7, reference numeral [Delta] P _max represents a pressure loss corresponding to the use limitation of the filter, reference numeral P _C denotes the replacement timing of the filter (the pressure loss at the time of exchange).

A characteristic curve L1 in FIG. 7 shows a fuel filter according to a normal product. For normal products, the travel distance K1 is the replacement time, and if there is no variation in quality between products (fuel filters), the travel distance K1 may be designated as the fuel filter replacement timing.
However, there is a case where the pressure loss does not increase with respect to the travel distance as in the characteristic curve L2 in FIG. In this case, the filter medium (filter paper) and the seal mechanism of the filter are damaged, or the filter mesh is large, so that dust to be repaired by the fuel filter passes through the filter, so that the pressure loss in the fuel filter does not increase. . In addition, dust that has not been repaired by the fuel filter flows into the engine, the fuel pump, or the like, which may cause damage or failure of these devices.

In the case of the characteristic curve L3 in FIG. 7, the pressure loss rapidly decreases at the time of the travel distance K3. Such a characteristic (characteristic of L3) is caused by, for example, the filter medium and the seal mechanism of the filter being damaged and the pressure loss being rapidly reduced at the travel distance K3.
Even in the case of the characteristic curve L3, the dust passes through the fuel filter and flows into the engine, the fuel pump, etc., which may cause damage or failure of these devices.

The filtering efficiency and quality of the filter required from the engine are required at a high level. The so-called genuine products and the filters specified by the manufacturer satisfy such a high level of filtration efficiency and quality. Therefore, the characteristic curves L2 and L3 described above hardly occur.
However, in the case of using a fuel filter that is not a genuine product or a filter designated by the manufacturer, in particular, an inexpensive fuel filter, there is a high possibility that cases such as the characteristic curves L2 and L3 described above will occur.

On the other hand, the conventional fuel filter life determination device is configured such that the warning light is turned on (or flashes) when the pressure loss reaches a specified value (P _max or P _C ). Therefore, in the case of the characteristic curves L2 and L3 described above, an abnormality cannot be detected. Therefore, it was impossible to detect the breakage of the filter.

As another conventional technique, the PM deposition amount is obtained from the differential pressure across the DPF for repairing the PM discharged from the engine body, and based on whether the PM deposition amount is consistent with the calculated value or the theoretical value, A technique for determining an abnormality has been proposed (see Patent Document 1).
However, the related art (Patent Document 1) is a technique related to PM repair in the exhaust system, and does not contribute to solving the above-described problem in the fuel supply system.
JP-A-2005-344619

  The present invention has been proposed in view of the above-described problems of the prior art, and provides a fuel filter replacement time determination device that can detect when a filter is damaged and pressure loss does not increase. It is aimed.

The fuel filter replacement timing determination device (100) of the present invention includes a first pressure sensor (6) for detecting the inflow side pressure of the fuel filter (4) and a second pressure for detecting the discharge side pressure of the fuel filter (4). Pressure sensor (7) and a control device (calculation unit 10), the control device (10) measures the measurement result of the first pressure sensor (6) and the measurement of the second pressure sensor (7). From the result, the differential pressure (P _A -P _B ) between the inflow side pressure (P _A ) and the discharge side pressure (P _B ) of the fuel filter (4) is obtained, and the differential pressure (P _A -P _B ) and filter replacement It has a function of determining whether or not the fuel filter (4) should be replaced based on the travel distance after (if it is a so-called “new car”, after delivery), and the control device (10) further includes the difference The basic characteristics of the pressure (P _A -P _B ) and the travel distance are stored, and the differential pressure ( When P _A -P _B ) is lower than the first threshold (α) with respect to the differential pressure “Lb (β)” of the same travel distance in the basic characteristics (P _A −P _B <β−α) Has a function of determining that an abnormality has occurred in the fuel filter (4) and giving a warning (for example, turning on the warning lamp 20).

  Here, it is preferable that the first pressure sensor (6) and the second pressure sensor (7) measure the pressure during the idling operation of the engine (1).

The fuel filter replacement time determination device (101) of the present invention detects a differential pressure (P _A -P _B ) between the inflow side pressure (P _A ) and the discharge side pressure (P _B ) of the fuel filter (4). It has a differential pressure sensor (8) and a control device (calculation unit 10), and the control device (10) is used for the differential pressure measured by the differential pressure sensor (8) and after the filter replacement (so-called “new car”). If so, it is preferable to have a function of determining whether or not the fuel filter (4) should be replaced based on the travel distance after delivery.

  Here, it is preferable that the differential pressure sensor (8) measures pressure during idling operation of the engine (1).

Furthermore, in the present invention, the control device (10) causes the fuel filter (4) to operate when the differential pressure (ΔP _n ) becomes larger than a third threshold value (use limit ΔP _max ) corresponding to the filter use limit. It is preferable to have a function of determining that the replacement time has come and giving a warning (for example, turning on the warning lamp 20).

According to the present invention having the above-described configuration, not only the differential pressure between the inflow side pressure and the discharge side pressure of the fuel filter (4), but also the travel after the filter replacement (after delivery for a so-called “new car”). Since it is determined whether or not the fuel filter (4) should be replaced in consideration of the distance, the difference depends on the filter part (filter material part 4f) in the fuel filter (4), the seal part, or other factors. Even if the pressure does not increase, it is possible to determine that the fuel filter (4) has failed.
Therefore, even if the filter part (filter material part 4f) or the seal part is damaged, the differential pressure does not increase, so that the situation where the fuel filter (4) is not replaced is surely prevented.
As a result, it is also possible to prevent foreign matter from entering from the damaged part of the filter part (filter material part 4f) or the seal part and damaging the equipment arranged on the downstream side of the fuel supply system.

More specifically, in the present invention, when the differential pressure (P _A -P _B ) is lower than the first threshold (α) with respect to the differential pressure (β) of the same travel distance in the basic characteristics ( If it is configured to determine that an abnormality has occurred in the fuel filter (4) in P _A -P _B <β-α (Claim 5), the fuel filter is originally damaged and the difference immediately after replacement is different. When the pressure does not increase (characteristic curve Lc in FIG. 2), the differential pressure (P _A -P _B ) immediately becomes the first threshold value (β) with respect to the differential pressure (β) of the same travel distance in the basic characteristics. Since the pressure is lower than α) (P _A −P _B <β−α), it is determined as abnormal and a warning is issued.

In the present invention, when the difference (ΔP _n −ΔP _{n + 1} ) from the differential pressure (ΔP _{n + 1} ) in the control cycle immediately after measuring the differential pressure (ΔP _n ) is smaller than a second threshold (for example, 0) ( If it is configured to determine that ΔP _n −ΔP _{n + 1} <0) is abnormal in the fuel filter (4) (Claim 6), the filter of the fuel filter (4) that has been operating normally until then When the portion (4f) or the seal portion is damaged, the differential pressure (ΔP _{n + 1} ) in the control cycle immediately after the failure is more surely reduced than the differential pressure (ΔP _n ) immediately before the failure. Then, it is reliably determined that an abnormality has occurred in the fuel filter (4), and a warning is issued.

Embodiments of the present invention will be described below with reference to the attached documents.
First, a first embodiment of the present invention will be described with reference to FIGS.
In FIG. 1, a fuel filter replacement time determination device 100 is a calculation that is a filter 4, a fuel supply line L1, a first pressure sensor 6, a second pressure sensor 7, a fuel flow sensor 9, and a control device. Unit 10.

  Inside the filter (filter case including the filter medium part) 4 is incorporated a filter part (filter medium part, for example, filter paper) 4f. The fuel supply line L1 includes a first line L11 that communicates the fuel tank 3 and the fuel filter 4, and a second line L12 that communicates the fuel filter 4 and the fuel injection device 2 of the engine 1. . Here, the fuel return line indicated by the symbol L2 communicates the fuel injection device 2 and the fuel tank 3.

The inlet near the filter 4 in the first line L11, the first pressure sensor 6 is interposed, which detects the pressure P _A of the fuel flowing into the filter 4. Then, the discharge opening neighborhood of the filter 4 in the second line L12, a second pressure sensor 7 is interposed, which detects the pressure P _A of the fuel to be discharged from the filter 4.
Further, in the second line L12, a flow rate sensor 9 for detecting the flow rate of the fuel is interposed in a region between the second pressure sensor 7 and the fuel injection device 2.

The fuel filter replacement time determination device 100 includes a vehicle speed sensor 51, an engine rotation sensor 52, an engine load sensor 53, a fuel temperature sensor 54, and a warning light 20 as warning means.
The calculation unit 10 includes a first pressure sensor 6, a second pressure sensor 7, a flow rate sensor 9, a vehicle speed sensor 51, an engine rotation sensor 52, an engine load sensor 53, a fuel temperature sensor 54, via an input signal line Si. The mileage meter 30 is connected. The calculation unit 10 and the warning lamp 20 are connected via a control signal line So.

Here, the first pressure sensor 6 and the second pressure sensor 7 are configured to measure pressure during idling operation of the engine. This is because the pressure fluctuation is large except during the idling operation, and it is difficult to accurately obtain the pressure difference between the first pressure sensor 6 and the second pressure sensor 7.
The first pressure sensor 6 and the second pressure sensor 7 are configured to measure pressure when the fuel temperature is a predetermined value (for example, 50 ° C.) or less. This is because when the fuel temperature is low, the viscosity value of the fuel increases and the pressure loss increases.

The calculation unit 10 stores a relationship between the travel distance K and the pressure loss ΔP, for example, characteristic curves Lb (β) and La (β−α) in FIG.
A characteristic curve Lb (β) is a characteristic curve (basic characteristic) serving as a base for the travel distance K and the pressure loss ΔP, and shows typical characteristics of the travel distance and the pressure loss ΔP in the filter 4.
The pressure loss at an arbitrary travel distance in the characteristic curve La (β-α) is a characteristic curve that is lower than the pressure loss at the same travel distance in the characteristic curve Lb (β) by a predetermined ratio. In other words, the characteristic curve La (β-α) is a characteristic curve that anticipates variations in quality in the fuel filter. For example, if the filter 4 has passed the inspection, unless it is an extremely abnormal use mode, A plot of an arbitrary travel distance and pressure loss ΔP in FIG. 2 always exists in a region above the characteristic curve La (β−α).
In other words, when the plot of the arbitrary travel distance and the pressure loss ΔP in FIG. 2 exists in a region below the characteristic curve La, the fuel filter 4 has a filter medium breakage or a sealing mechanism. The characteristic curve La (β−α) is a characteristic curve in which there is always a problem such as breakage.

In the first embodiment, in FIG. 2, a warning is issued when the pressure loss ΔP reaches the limit line L _max and when the pressure loss ΔP becomes a region below the characteristic curve La (β-α). It is configured.
In FIG. 2, the characteristic curve Lc is lower than the characteristic curve La (β-α) at the initial stage of use, so that a warning is issued at the initial stage of use. Although not shown, of course, it initially exceeds the characteristic curve La (β-α), but if the pressure loss falls below the characteristic curve La (β-α) as the mileage increases, it will fall below the characteristic curve La (β-α). A warning is issued at that time.
The characteristic curve Ld is smaller than the characteristic curve Lb (β) based on the pressure loss, but always exceeds the characteristic curve La (β−α). Therefore, the fuel filter having the characteristics shown by the characteristic curve Ld is within the allowable range of product variations. In the characteristic curve Ld, when the pressure loss ΔP reaches the limit line ΔP _max (a line parallel to the horizontal axis where the pressure loss is ΔP _max ) (travel distance Kx), a warning that the replacement time has come is issued. To emit.

Here, the warning content (for example, flashing length and interval) is different between the warning issued when the characteristic curve La (β−α) falls below and the warning when the limit line _Lmax is reached. It is desirable to configure.

Next, control for determining the replacement time of the fuel filter according to the first embodiment will be described based on the flowchart of FIG.
In step S1 of FIG. 3, the pressure P _A of the inflow side of the filter 4 is measured by the first pressure sensor 6, the second pressure sensor 7 measures the pressure P _B in the discharge side of the filter 4.
In the next step S2, the calculation unit 10 obtains the pressure difference between the pressure P _B of the pressure P _A of the inflow-side discharge side (pressure loss "P _A -P _B = [Delta] P"), the differential pressure Figure 2 It is determined whether or not the region is below the characteristic curve La (β−α). For simplification of illustration, in step S2 of FIG. 3, “P _A −P _B <β−α?” Is simply displayed, but this means that the pressure difference (pressure loss “P _A −P _B = ΔP ”) is a region below the characteristic curve La (β−α) in FIG.

If the area under the differential pressure (pressure loss "= ΔP _P A -P _B") of the characteristic curve La FIG 2 (beta-alpha) (step S2 is YES), the process proceeds to step S3, the fuel filter 4 A warning is given by blinking the warning lamp 20 as a warning means.
Differential pressure determined that (pressure loss _"P A -P _B = _ΔP") if the characteristic curve La (beta-alpha) over the region of FIG. 2 (Step S2 is NO), the fuel filter 4 is no abnormality Then, it returns to step S1 and repeats step S1 and subsequent steps.
Although not explicitly shown in FIG. 3, when a differential pressure “P _A -P _B ” reaches a limit value ΔP _max at an arbitrary travel distance, a warning is issued and the fact that the fuel filter replacement time has been reached is reached. It is configured to let you know.

According to the first embodiment having the above-described configuration, not only the differential pressure between the inflow side pressure and the discharge side pressure of the fuel filter 4 but also the travel distance after filter replacement (after delivery for a so-called “new car”). Therefore, it is determined whether or not the fuel filter 4 should be replaced. Therefore, the difference is caused by the filter part (filter material part) 4f in the fuel filter 4, the seal part, or other factors. Even when the pressure does not increase, it is possible to determine that the fuel filter 4 has failed.
Therefore, even if the filter part 4f is damaged or the seal part is damaged, the differential pressure does not increase, so that the fuel filter 4 is not replaced.
As a result, it is also possible to prevent foreign matter from entering from the damaged portion of the filter medium portion 4f and the seal portion and damaging the device arranged on the downstream side of the fuel supply system.

Next, a second embodiment will be described with reference to FIGS. 4 and 5.
The configuration of the second embodiment is the same as that of the first embodiment, but the mode of control is different from that of the first embodiment.
In the second embodiment shown in FIGS. 4 and 5, the pressure loss (differential pressure) is obtained every time a predetermined control timing, for example, a predetermined travel distance (k: 10 km, for example) is traveled, and the measured value of the current differential pressure is measured. However, if it falls below the previous measured value (differential pressure), it is determined that a failure has occurred in the filter 4 and a warning is issued.

4 represents that a situation similar to that shown by the characteristic curve line L3 in FIG. 7 has occurred in a characteristic diagram similar to FIG.
As is apparent from the plot of the characteristic curve indicated by the dotted line in FIG. 4, the pressure loss is measured every predetermined travel distance “k”. Assuming that the pressure loss (differential pressure) at the travel distance “n” is ΔP _n and the pressure loss at the next travel distance “n + 1” is ΔP _{n + 1} , the pressure loss is compared with ΔP _n. ΔP _{n + 1} decreases rapidly.

If the filter is in a normal state, the pressure loss (differential pressure) increases as the travel distance increases. It is unlikely that the pressure loss (differential pressure) decreases as the travel distance increases.
Therefore, in the second embodiment, when the measured value (ΔP _{n + 1} ) at the current time (travel time “n + 1”) is lower than the previous measured value (ΔP _n ) at the travel time “n”, It is determined that a problem has occurred in the filter, and a warning is issued. That is, a warning is issued when ΔP _n −ΔP _{n + 1} > 0.
A characteristic curve Lb (β) in FIG. 4 is a characteristic curve serving as a base, as described with reference to FIG.

Hereinafter, with reference to the flowchart of FIG. 5, control for determining the replacement time of the filter according to the second embodiment will be described.
In step S11 of FIG. 5, the pressure P _An on the inflow side and the pressure P _Bn on the discharge side at an arbitrary time point (hereinafter referred to as “previous”) of the filter 4 are measured. In step S12, the process waits until the predetermined timing elapses, that is, until the vehicle travels a predetermined distance (k) after the previous measurement (NO loop in step S12). If the vehicle travels a predetermined distance (k) (step S12). Is YES), the process proceeds to step S13. In step S13, the inflow side pressure P _{An + 1} and the discharge side pressure P _{Bn + 1} at a time point (hereinafter referred to as “this time”) traveled a predetermined distance (k) from an arbitrary time point are measured.

In step S14, a differential pressure ΔP _n (= P _An −P _Bn ) at the previous measurement and a differential pressure ΔP _{n + 1} (= P _{An + 1} −P _{Bn + 1} ) at the current measurement are obtained, and the differential pressure ΔP is determined from the differential pressure ΔP _{n. It} is determined whether or not a value obtained by subtracting _{n + 1} is smaller than zero.
As described above, if the fuel filter is in a normal state, the pressure loss (differential pressure) increases as the travel distance increases. Therefore, in a fuel filter in a normal state, ΔP _n −ΔP _{n + 1} ≦ 0.
Then, for example, when the fuel filter is broken, such as “n” and “n + 1” in the characteristic curve indicated by the dotted line in FIG. 4, ΔP _n −ΔP _{n + 1} > 0.

Therefore, if ΔP _n −ΔP _{n + 1} > 0 (YES in step S14), it is determined that an abnormality has occurred in the fuel filter, the process proceeds to step S15, and a warning is issued.
On the other hand, if ΔP _n −ΔP _{n + 1} ≦ 0 (NO in step S14), it is determined that the fuel filter is in a normal state, the process returns to step S11, and step S11 and subsequent steps are repeated.
Also in the second embodiment described with reference to FIGS. 4 and 5, when the differential pressure “P _A −P _B ” reaches the limit value ΔP _max at an arbitrary travel distance, the replacement timing of the fuel filter is changed. Issue a warning that it has arrived.

According to the second embodiment of FIGS. 4 and 5, the difference (ΔP _n −ΔP _{n + 1} ) from the differential pressure ΔP _{n + 1} in the control cycle immediately after measuring the differential pressure ΔP _n is greater than the second threshold (for example, 0). Is smaller, that is, when ΔP _n −ΔP _{n + 1} <0, it is determined that an abnormality has occurred in the fuel filter 4. Therefore, when the filter portion 4f or the seal portion of the fuel filter 4 that has been operating normally up to a certain point (travel distance) is suddenly damaged, the differential pressure ΔP _{n + 1} in the control cycle immediately after the failure is the differential pressure immediately before the failure. reliably determined by that steps down than [Delta] P _n, it can be alert.

Note that “0” is selected as the threshold value of ΔP _n −ΔP _{n + 1} in the second embodiment of FIGS. 4 and 5. That is, if ΔP _n −ΔP _{n + 1} <0, it is determined that an abnormality has occurred in the fuel filter 4.
However, the threshold value of ΔP _n −ΔP _{n + 1} is not limited to “0”. It can be set on a case-by-case basis according to various conditions.
Also, the “timing” between control cycles, that is, the travel distance (predetermined distance k) corresponding to the time between the previous control cycle and the current control cycle can be set as appropriate according to various conditions.

Next, a third embodiment will be described with reference to FIG.
The first embodiment of FIGS. 1 to 3 is equipped with two pressure sensors, a first pressure sensor (filter inflow side sensor) 6 and a second pressure sensor (filter outflow side sensor) 7.
On the other hand, as shown in FIG. 6, the filter replacement time determination device 101 according to the third embodiment provides one differential pressure sensor 8 across the line L11 and the line L12. The differential pressure between the inflow side pressure and the discharge side pressure can be measured.
The replacement time determination in the third embodiment of FIG. 6 can be performed according to the control flowchart of FIG. 3, or can be performed according to the control flowchart of FIG.
Other configurations and operational effects in the third embodiment of FIG. 6 are the same as those of the embodiment of FIGS.

  The illustrated embodiment is merely an example, and is not intended to limit the technical scope of the present invention. That is, it is possible to determine the replacement time of the fuel filter by combining the first embodiment and the second embodiment. Similarly, in the third embodiment of FIG. 6, the control shown in the flowchart of FIG. 3 and the control shown in the flowchart of FIG. 5 can be combined.

The block diagram of 1st Embodiment of this invention. FIG. 5 is a travel distance-pressure loss characteristic diagram illustrating the principle of filter replacement time determination in the first embodiment of the present invention. The flowchart which shows the control in 1st Embodiment of this invention. The characteristic figure of the mileage-pressure loss explaining the principle of filter replacement time determination in 2nd Embodiment of this invention. The flowchart which shows the control in 2nd Embodiment of this invention. The block diagram of 3rd Embodiment of this invention. The characteristic figure of the mileage-pressure loss explaining the principle of filter replacement time determination in a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Fuel-injection apparatus 3 ... Fuel tank 4 ... Fuel filter (case)
4 ... Filter (filter paper)
5 ... feed pump 6 ... first pressure sensor 7 ... second pressure sensor 8 ... differential pressure sensor 9 ... flow rate sensor 10 ... control device / calculation unit 20 ... Warning means / warning lamp 100 ... Fuel filter life determination device

Claims (1)

A first pressure sensor (6) for detecting the inflow side pressure of the fuel filter; a second pressure sensor (7) for detecting the discharge side pressure of the fuel filter (4); and a control device (10). The control device (10) determines the inflow side pressure (P _A ) and the discharge side pressure of the fuel filter (4) from the measurement result of the first pressure sensor (6) and the measurement result of the second pressure sensor (7). obtains a differential pressure _(P a -P _B) between _{(P B),} and a said differential pressure _(P a -P _B) and the travel distance after filter replacement, whether to replace the fuel filter (4) Further, the control device (10) stores basic characteristics of the differential pressure (P _A -P _B ) and the travel distance, and the differential pressure (P _A -P _B ) Is lower than the first threshold (α) with respect to the differential pressure “Lb (β)” of the same travel distance in the basic characteristics The case fuel filter replacement timing determination device and having a function of warning is determined that the abnormality in the fuel filter (4) has occurred.

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