JPH0422808Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a filter diagnostic device for diagnosing blockage or damage to a filter provided in a lubricating oil system, fuel supply system, etc. of an internal combustion engine.

<Prior Art> Conventionally, for example, the lubricating oil system of a diesel engine is provided with a filter for filtering the lubricating oil, and in order to check for clogging of the filter or damage to the filter due to filtered sludge, the filters are installed before and after the filter. A differential pressure gauge is provided to detect the pressure difference in lubricating oil. During patrol monitoring and periodic inspections, the driver reads the pressure difference indicated by the pointer of the differential pressure gauge and determines whether the filter is clogged or damaged by referring to the accumulated usage time of the filter. .

<Problems to be solved by the invention> However, since the conventional filter diagnosis method described above only displays the pressure difference before and after the filter using the pointer of a differential pressure gauge, it is difficult to accurately discover abnormalities in the filter. , the judgment must be made by a skilled driver with many years of experience and know-how. Therefore,
Conventional diesel engines have the disadvantage that they require a skilled operator to frequently check the differential pressure gauge, making it impossible to save labor and manpower for engine operation. In addition, the conventional filter abnormality diagnosis method described above relies on the driver's visual observation and judgment based on experience, so it is inevitable that abnormalities will be overlooked due to misidentification, and the filter differential pressure will be determined appropriately according to the cumulative usage time. It is also difficult to accurately judge whether this is the case. There is also the possibility that such misidentification or oversight of a slight abnormality may lead to serious failure or damage to the engine due to poor lubrication.

Therefore, the purpose of the present invention is to quickly and accurately identify abnormalities such as filter blockage or damage based on the pressure difference before and after the filter by providing a new discrimination method based on conventional experience and experimental data. It is an object of the present invention to provide a filter diagnostic device that can output the determination results as information, thereby contributing to labor saving and efficiency in engine operation and maintenance.

<Means for solving the problem> In order to achieve the above object, the filter diagnostic device of the present invention uses a differential pressure sensor that detects the pressure difference between the liquid before and after the filter installed in the lubricating oil system of an internal combustion engine. , a maximum value holding means for holding the maximum value of the detection signal detected by the differential pressure sensor during a period up to a certain time period from the time of determination; differential pressure determining means for determining whether or not the filter differential pressure is excessive; warm-up operation determining means for determining whether the filter differential pressure is excessive; The present invention is characterized in that it is diagnosed that the filter is clogged or is likely to be clogged.

<Operation> The differential pressure sensor detects the differential pressure of lubricating oil before and after a filter provided in the lubricating oil system of an internal combustion engine, for example, and outputs a detection signal to the maximum value holding means and the filter differential pressure determining means. The maximum value holding means holds the maximum value of the detection signal inputted before the judgment, while the filter differential pressure determining means compares the detection signal at the judgment and the maximum value, and determines the maximum value at the judgment. It is determined whether or not the filter differential pressure is excessive. When the filter differential pressure determining means determines that the filter differential pressure is excessive, the warm-up operation determining means determines whether or not the internal combustion engine is being warmed up. As a result, if the filter differential pressure is excessive even though the engine is not being warmed up, it is diagnosed that the filter is clogged or is likely to be clogged.

<Example> Hereinafter, the present invention will be explained in detail with reference to the illustrated example.

Figure 1 is a schematic diagram of the lubricating oil system of a diesel engine equipped with the filter diagnostic device of the present invention.
is a tank that stores lubricating oil, 2 is a pump that pumps the lubricating oil from tank 1, 3 is an oil cooler that cools the pumped lubricating oil with water, and 4 is the amount of oil that bypasses this oil cooler 3 and the oil that flows through it. Automatically adjusts the amount ratio,
A temperature control valve that maintains the temperature of the lubricating oil being pumped at a set temperature; 5 a filter that filters the lubricating oil that has passed through the temperature control valve 4; and 6 a differential pressure sensor that detects the pressure difference between the lubricating oil before and after the filter 5. , 7 is provided with a maximum value holding means, a differential pressure determining means, a warm-up operation determining means, and a filter replacement determining means, which will be described later, and is a diagnostic for diagnosing an abnormality in the filter 5 based on a detection signal inputted from the differential pressure sensor 6. A computer 8 is a display device that displays the diagnostic results output from the computer 7.

Further, 9 is a pressure regulating valve that adjusts the pressure of the lubricating oil that has passed through the filter 5 to an appropriate supply pressure, and 10 is a pressure regulating valve 9 that is connected to each piston 1 of the diesel engine.
1 is a piston oil supply pipe that sends lubricating oil, and 12 is a pipe that connects the pressure regulating valve 9 to the crankshaft 13 of the diesel engine.
14 is a filter interposed in the bearing oil supply pipe 12, and 15 is a return pipe for collecting the lubricating oil accumulated in the oil pan 16 of the diesel engine into the tank 1. be.

FIG. 2 is a diagram showing an example of a change over time in the filter differential pressure ΔP detected by the differential pressure sensor 6 of the filter 5. As shown in FIG. After the filter differential pressure ΔP gradually decreases from a high pressure state (not shown) in which a sudden change in pressure occurs in the lubricating oil during warm-up operation immediately after the start of engine operation,
During steady operation, it changes as shown by the curve in Figure 2. Filter differential pressure reference value ΔPn indicated by the broken line in the figure
indicates the average value of filter differential pressure during steady operation,
The upper limit value ΔPad shown by the two-dot chain line in the figure is the difference between the design pressure Pd on the inflow side of the filter 5 and the alarm pressure Pa on the outflow side when the filter is closed, and indicates the filter differential pressure when the filter is closed. The maximum value holding means of the computer 7 is a time series of a detection signal representing the filter differential pressure detected by the differential pressure sensor 6 and input from a certain time a before the designated judgment time ti shown in FIG. The maximum value ΔPmax and minimum value ΔPmin of the data ΔPj are detected and held (see step S2 in FIG. 3).

The differential pressure determination means of the computer 7 uses the detection signal ΔPi of ti at the time of the above judgment and the value k(t)·ΔPmax obtained by multiplying the maximum value ΔPmax by a constant k(t) corresponding to the occlusion of the filter over time. It is determined whether or not the filter differential pressure ΔPi at the time of judgment is excessive (see step S3 in FIG. 3). When it is determined that the filter differential pressure ΔPi is not excessive, this filter differential pressure ΔPi and the filter differential pressure reference value ΔPn are compared and determined (see step S8 in FIG. 3). Next, when it is determined that ΔPi<ΔPn, the magnitude of the filter differential pressure ΔPi and the minimum value ΔPmin is compared and determined, and when it is determined that ΔPi≦ΔPmini, it is determined whether or not the diesel engine is stopped. (See steps S9 and S10 in FIG. 3). And even though the engine is running, the filter differential pressure ΔPi
are filter differential pressure reference value ΔPn and minimum value ΔPmin
When it is determined that the filter differential pressure is lower than ).

The warm-up operation determining means of the computer 7 determines that when the differential pressure determining means determines that the filter differential pressure ΔPi is excessive (ΔPi≧k(t)・ΔPmax), the diesel engine It determines whether or not warm-up operation is in progress, and when it determines that it is not in warm-up operation, it determines that the increase in filter differential pressure is large even though the viscosity of the lubricating oil is low. ” (3rd
(See steps S4 and S5 in the figure). Also, when it is determined that the warm-up operation is in progress, the above filter differential pressure ΔPi
is the filter differential pressure reference value ΔPn ₀ during warm-up operation
It is determined whether or not it is larger than the lower limit value k ₀ ΔPn ₀ multiplied by a constant k ₀ (k ₀ <1), and when it is determined that it is not, it is determined that there is no predetermined increase in the filter differential pressure. , information regarding the determination result and the cause of the abnormality "filter damage, sensor abnormality" is output (see steps S6 and S7 in FIG. 3).

Further, the filter replacement determining means of the computer 7 determines whether the filter differential pressure ΔPi is the filter differential pressure reference value ΔPn or the minimum value ΔPmin by the differential pressure determining means.
When it is determined that the filter differential pressure ΔPi is larger than the filter differential pressure reference value ΔPn, the deviation of the filter differential pressure ΔPi from the filter differential pressure reference value ΔPn is calculated, and it is determined whether or not this deviation is excessive. That is, as shown in step S11 of FIG. 3 and FIG.
ΔPi)/(ΔPad−ΔPn) is used as an index to indicate the filter clogging tendency, and whether or not the filter is clogged is determined by whether or not this ratio becomes smaller than a certain value k ^* based on experience (for example, k ^* = 0.5). do. and,
When it is determined that (ΔPad−ΔPi)/(ΔPad−ΔPn)≦k ^* , the cumulative usage time τ of the filter is calculated from the cumulative total engine operating time, and this cumulative usage time τ reaches the predetermined maintenance time τ ₀ . If it is determined that τ≧τ ₀ , it will provide information indicating that the filter needs to be cleaned or replaced, and if it is determined that τ<τ ₀ , it will provide information that indicates that the filter may be clogged. The information shown is output to the display device 8 (see steps S13 to S16 in FIG. 3).

The diagnostic processing of the computer 7 having the above configuration will now be described with reference to the flowchart of FIG.

S1 Computer 7 contains, prior to diagnosis,
Constant data includes constants k(t), k ^* , k ₀ , filter differential pressure reference value ΔPn during steady and warm-up operation,
ΔPn ₀ and the upper limit value ΔPad of the filter differential pressure are input,
When the diesel engine starts, time series data ΔPj of a detection signal representing the filter differential pressure is input from the differential pressure sensor 6 provided in the lubricating oil filter 5.

S2 The maximum value holding means detects the maximum value ΔPmax and minimum value ΔPmin based on the time-series data ΔPj input from a time before the judgment time ti, and holds these ΔPmax and ΔPmin.

S3 The differential pressure determination means subtracts the filter differential pressure ΔPi at the time of the above determination from the product k(t)・ΔPmax of the maximum value ΔPmax and the constant k(t), determines whether the subtraction result is positive or negative, and determines whether the subtraction result is negative. Or if 0, step S4
If the subtraction result is positive, the process advances to step S8.

S4 Since the filter differential pressure ΔPi was determined to be excessive in the previous step, the warm-up operation determining means determines whether or not the diesel engine is warming up, based on, for example, the time elapsed since the engine was started, and warms up the diesel engine. If it is determined that the filter is in operation, the process proceeds to step S6, whereas if not, it is determined that the filter differential pressure is high even though it is in steady operation, and in step S5 diagnostic information indicating "large increase in filter differential pressure, filter blockage" is provided. Output.

S6 The warm-up operation determining means that determined that the warm-up operation is in progress in the previous step subtracts the product of the filter differential pressure reference value ΔPn ₀ during warm-up operation and the constant k ₀ from the filter differential pressure ΔPi, and calculates the sign of the subtraction result. Determine. and,
If the subtraction result is positive, it is determined that the filter differential pressure ΔPi is appropriate, and the routine returns to step S1 to continue, while if the subtraction result is negative or 0, it is determined that the filter differential pressure is low despite the warm-up operation. Then, in step S7, diagnostic information indicating "no rise in filter differential pressure, filter damage, sensor abnormality" is output.

S8 The differential pressure determining means that determined that the filter differential pressure ΔPi is not excessive in the previous step S3 subtracts the filter differential pressure reference value ΔPn during steady operation from the filter differential pressure ΔPi, determines whether the subtraction result is positive or negative, and performs the subtraction. If the result is positive or 0, it is assumed that ΔPi is not too small and the process proceeds to step S11. If the result of the subtraction is negative, the process proceeds to step S9 for the next determination.

S9 Differential pressure determination means uses the filter differential pressure ΔPi
The minimum value ΔPmin held in step S2 is subtracted from the subtraction result, and whether the subtraction result is positive or negative is determined. If the subtraction result is positive, it is determined that ΔPi is not too small, and the process proceeds to step S11. If the subtraction result is negative or 0, ΔPi is too small, and the process proceeds to step S10, in which it is determined whether the diesel engine is stopped or not. Determine. Then, if it is determined that it is stopped,
Even if ΔPi is too small, it is not abnormal, so step S11
If it is determined that the engine is not stopped, it is determined that ΔPi is too small even though it is in operation, and in step S12, diagnostic information indicating "no rise in filter differential pressure, filter damage" is output.

S11 Since it was determined in the previous step that the filter differential pressure ΔPi is not too small, the filter replacement determining means determines whether or not the filter is clogged due to use over time, from a different perspective from the excessive determination made by the differential pressure determining means in step S3. Discern. That is, the filter replacement determining means calculates an index (ΔPad−ΔPi)/(ΔPad−ΔPn) indicating the filter clogging tendency from the filter differential pressure ΔPi at the time of determination, the upper limit value ΔPad of the filter differential pressure, and the filter differential pressure reference value ΔPn. Then, compare and determine the magnitude of this calculated value and the constant k ^* . When the calculated value is larger than k ^* , it is determined that the filter is not blocked and the process proceeds to step S17.
When the above calculated value is smaller than k ^* , step S
Proceed to step 13.

S13 The filter replacement determination means calculates the cumulative usage time τ of the filter, and in the following step S14,
It is determined whether this cumulative usage time τ is equal to or greater than the maintenance time τ ₀ . and τ≧τ ₀
If it is determined that τ < τ 0, the process proceeds to step S15 and outputs information indicating that "the filter needs to be cleaned or replaced." On the other hand, if it is determined that τ<τ ₀ , the information indicating that the filter needs to be replaced is "filter clogged". Outputs the information "Possible."

S17 Finally, the computer 7 determines whether or not to continue the above-described diagnostic routine based on a command signal input from the outside. If it continues, the process returns to step S1; otherwise, the process ends.

In this way, in the above embodiment, the computer 7
The maximum value holding means detects and holds the minimum value ΔPmin of the filter differential pressure, and the differential pressure determining means determines whether the filter differential pressure ΔPi at the time of judgment is larger than the filter differential pressure reference value ΔPn and the minimum value ΔPmin. Also, it is determined whether the engine is stopped or not, and the warm-up operation determination means uses the filter differential pressure ΔPi.
In addition to determining whether or not ΔPn 0 is greater than the lower limit value k ₀ · ΔPn ₀ during warm-up operation, the filter replacement determination means can grasp the tendency of filter clogging due to use over time, making it possible to diagnose filter abnormalities in a variety of ways and in detail. This makes it possible to accurately and easily detect filter abnormalities throughout the entire period of use without the need of a skilled operator, which saves labor and improves the efficiency of engine operation and maintenance. Serious breakdowns and damage to diesel engines due to poor lubrication can be prevented. Also,
Since all diagnostic results are displayed on the display device 8,
The driver's effort in monitoring the engine can be reduced, and failures in the filter to be overlooked are also reduced.

Note that the processing methods of the maximum value holding means, differential pressure determining means, and warm-up operation determining means of the filter diagnostic device of the present invention are not limited to the processing methods of the above embodiments.
It goes without saying that the filter diagnostic device of the present invention can also be applied to filters in the fuel supply system of internal combustion engines.

<Effects of the invention> As is clear from the above explanation, the filter diagnosis device of the invention uses a differential pressure sensor to detect the pressure difference between the fluid before and after the filter installed in the lubricating oil system of an internal combustion engine, and makes a judgment. The maximum value of the detection signal detected by the differential pressure sensor during a period up to a certain time before the current time is held in the maximum value holding means, while the detection signal at the time of judgment and the maximum value are compared by the differential pressure discrimination means. In addition, when it is determined that the filter differential pressure is excessive, the warm-up operation determination means determines whether the internal combustion engine is being warmed up. , when it is determined that the filter differential pressure is excessive and the filter is not being warmed up, it is diagnosed that the filter is clogged, so it does not require a skilled operator to automatically detect an abnormality in the filter differential pressure. It is possible to quickly and reliably diagnose filter blockage or damage and output it as information, allowing filter abnormalities to be detected accurately and easily, greatly contributing to labor savings and efficiency in engine operation and maintenance.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the lubricating oil system of a diesel engine equipped with the filter diagnostic device of the present invention, and Figure 2 shows the change over time in the filter differential pressure detected by the differential pressure sensor installed on the filter in Figure 1. A diagram showing an example,
FIG. 3 is a flowchart showing the flow of diagnostic processing of the computer shown in FIG. 1...Tank, 2...Pump, 5...Filter, 6...Differential pressure sensor, 7...Computer, 8
... Display device, 10 ... Piston oil supply pipe, 11 ...
... Piston, 12 ... Bearing oil supply pipe, 13 ... Crankshaft, 15 ... Return pipe, 16 ... Oil pan.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A filter diagnostic device for diagnosing blockage or damage to a filter installed in the lubricating oil system or fuel supply system of an internal combustion engine, which detects the pressure difference between the liquid before and after the filter. a differential pressure sensor for detecting; a maximum value holding means for holding the maximum value of the detection signal detected by the differential pressure sensor during a period up to a certain time before the time of determination;
differential pressure determining means for determining whether the filter differential pressure at the time of determination is excessive by comparing the detection signal at the time of the determination with the maximum value; and a warm-up operation determining means for determining whether or not the internal combustion engine is in warm-up operation, the differential pressure determining means determining that the filter differential pressure is excessive;
A filter diagnostic device characterized in that, when the warm-up operation determination means determines that the warm-up operation is not in progress, the filter is diagnosed as being clogged or being slightly clogged. (2) In the filter diagnostic device according to claim 1 of the above utility model registration claim, when the filter differential pressure determining means determines that the filter differential pressure is not excessive, the filter difference indicated by the detection signal at the time of the determination is determined. The deviation between the pressure and a predetermined filter differential pressure reference value is calculated, and it is determined whether or not this deviation is excessive. When the deviation is determined to be excessive, the cumulative usage time of the filter is determined by the predetermined maintenance. A filter diagnostic device characterized by comprising a filter replacement determining means for determining whether filter replacement is necessary or not by comparing with time.