JP2001200712A - Oil change time detecting device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil change time detecting device for diesel engine, capable of relatively easily detecting the appropriate time for replacement of the engine oil. SOLUTION: An electronic control device (ECU) 26 computes the soot containing quantity during the prescribed computing period on the basis of the engine speed, fuel injection quantity, air-fuel ratio and fuel injection time of a diesel engine 10, and computes the soot quantity included in the engine oil while integrating results of the computing. When the computed soot quantity exceeds the prescribed limit value, time for replacement of the engine oil is detected, and an indicator 27 is lighted to be notified of this.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine oil change timing detecting device for detecting a timing of changing engine oil based on a calculation result of a suit amount in engine oil.

[0002]

2. Description of the Related Art In a diesel engine, sooted unburned fuel (suit) is mixed into engine oil and adversely affects the lubricity. Therefore, it is necessary to change the engine oil when the amount of the suit in the engine oil exceeds a predetermined amount.

[0003] Conventionally, in vehicles equipped with a diesel engine, the oil change timing is generally determined using the mileage of the vehicle as an index. However, it is difficult to say that the traveling distance strictly reflects the amount of the suit mixed into the engine oil, which may cause inappropriate oil change.

Therefore, as a detection device for detecting a more appropriate oil change timing, for example, an oil change timing detection device described in Japanese Patent Publication No. 58-20916 is known.
In this oil change timing detection device, the total amount of the suit in the engine oil is calculated by sequentially calculating the amount of the suit mixed into the engine oil during a predetermined calculation period based on the operating state of the engine, and integrating the calculation results. Like that. Then, when the calculated total amount of the suit in the engine oil exceeds a predetermined limit value, the oil change timing is detected.

[0005] In the detection device described in the above publication, the suit mixing amount Tst in a predetermined calculation period is calculated based on the following equation (a) obtained in advance through experiments.

Tst = k1 · F1 ｛n, L｝ · V · (k2 · e + k3) · k4 (a) where “k1” to “k3” are predetermined constants determined by the engine model and the like, and “k4” "" Indicates the carbon weight ratio in the suit, "n" indicates the engine rotation speed, "L" indicates the fuel injection amount (engine load), and "e" indicates the EGR rate (the ratio of EGR gas to the intake air amount). , “V” respectively indicate the intake air amount calculated as a function of the engine rotation speed n. Further, the function F1 {n, L} is a function indicating the degree of generation of a suit by combustion.

That is, in this detection device, the amount of soot mixed into the engine oil during the predetermined calculation period is mainly determined by the engine speed n and the fuel injection amount L (for a diesel engine introducing EGR gas, the EGR rate e ). Then, the oil change timing is detected when the calculated suit mixing amount exceeds a predetermined limit value.

[0008]

As described above, the above equation (a)
, The engine speed n, the fuel injection amount L and the EGR
If the above-mentioned suit mixing amount is calculated based on the rate e, it is possible to detect an appropriate oil change time.

However, more strictly speaking, in addition to the engine rotation speed n, the fuel injection amount L and the EGR rate e, factors such as the air-fuel ratio and the fuel injection timing, which will be described later, are also deeply involved in the suit mixing amount. Because of these three parameters, it is not possible to directly determine the suit mixing amount. Therefore, in order to accurately obtain the suit mixing amount from the above equation (a), the correspondence (function F1 {n, L}) between the engine rotation speed n, the fuel injection amount L, and the suit mixing amount is determined in advance. It is necessary to keep track of the entire operating range of the engine. In addition, since the correspondences differ depending on the engine model, it is necessary to confirm the correspondences in advance by experiments or simulations for each of the applicable models.

Particularly in recent years, even in diesel engines, engine control has become complicated due to demands for improved emission and improved fuel efficiency, such as fine control of intake air amount, and the correspondence between them has been grasped in advance. It is becoming increasingly difficult to do so. In addition, with such complicated engine control, it is often the case that not all the factors affecting the suit mixing amount can be uniquely determined from the engine rotation speed n and the fuel injection amount L. Simply based on the injection amount L and the EGR rate e, it is not always possible to accurately determine the engine oil replacement time.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a diesel engine oil change timing detecting device capable of relatively easily detecting a proper engine oil change timing. Is to do.

[0012]

The means for achieving the above object and the effects thereof will be described below. According to a first aspect of the present invention, there is provided a diesel engine oil replacement timing detecting apparatus for detecting a replacement timing of an engine oil based on a calculation result of a suit amount in the engine oil of the diesel engine. The suit amount in the engine oil is calculated based on the rotation speed, the fuel injection amount, and the air-fuel ratio.

The amount of soot produced in the engine increases as the amount of fuel burned increases, and it is needless to say that the amount of suit generation is largely proportional to the amount of fuel injected, but is also greatly affected by the combustion state of the fuel. . For example, in a situation where there is a sufficient amount of air (oxygen) in the combustion chamber and most of the injected fuel is completely burned, less suits are generated and the injected fuel is air ( Insufficient oxygen will result in the production of large amounts of suits due to incomplete combustion. Therefore, the generation amount of the suit and the degree of mixing of the suit into the engine oil greatly depend on the amount of air with respect to the injected fuel, that is, the air-fuel ratio.

Therefore, in the configuration according to the first aspect,
The suit amount in the engine oil is calculated based on the engine speed, the fuel injection amount, and the air-fuel ratio.
To grasp the total amount of injected fuel from the engine speed and the fuel injection amount, and from the air-fuel ratio to know the proportion of the injected fuel that will be converted into a suit after combustion (suit conversion rate). Can be. Therefore, based on the engine rotation speed, the fuel injection amount, and the air-fuel ratio, it is possible to accurately determine the suit generation amount in the engine and, consequently, the suit amount in the engine oil. As a result, the degree of deterioration of the engine oil can be accurately grasped, and the appropriate oil change time can be accurately detected.

Further, the suit mixing amount can be accurately obtained without having to grasp in advance the correspondence between the engine rotational speed, the fuel injection amount, and the like and the suit mixing amount over the entire operation range of the engine. The application of the detection device is relatively easy. Therefore, according to the first aspect of the present invention, it is possible to relatively easily detect an appropriate engine oil replacement time.

The above-mentioned amount of EGR gas (EGR rate)
In addition, since the fuel injection timing described later also affects the degree of mixing of the suit into the engine oil, it is preferable to calculate the suit amount in consideration of these factors. However, if the effects are sufficiently small and negligible, by using the engine speed, the fuel injection amount and the air-fuel ratio in the calculation of the suit mixing amount as in the above configuration, a sufficiently appropriate engine The time to change the oil can be easily detected.

According to a second aspect of the present invention, there is provided a diesel engine oil change timing detecting means for detecting a timing of changing the engine oil based on a calculation result of a suit amount in the engine oil of the diesel engine. In the apparatus, a suit amount in the engine oil is calculated based on an engine rotation speed, a fuel injection amount, and a fuel injection timing.

In a diesel engine, the timing of fuel injection sometimes affects the degree of mixing of a suit into engine oil. In particular, in a direct injection type diesel engine in which fuel is directly injected into a cylinder, as described below, the fuel injection timing may greatly influence the degree of mixing of a suit into engine oil.

In general, in a direct injection diesel engine, as shown in FIG. 1, an injector 5 disposed above a combustion chamber 6 of a cylinder 1 enters a concave cavity 4 formed on a top surface 3 of a piston 2. Fuel is injected toward it. At this time, most of the fuel injected when the piston 2 is located near the top of the cylinder 1 (near top dead center), as shown in FIG. .

However, as shown in FIG. 2B, the fuel injected when the piston 2 is located below cannot be contained in the cavity 4 and a part thereof is
Scatters on the top surface 3 of the cylinder 1 and jumps on the peripheral wall of the cylinder 1 while burning. As a result, the suit generated by the combustion of the fuel is directly mixed into the engine oil on the peripheral wall of the cylinder 1, so that the amount of the suit mixed in the engine oil greatly increases.

The amount of fuel overflowing from the cavity 4 and splashing on the peripheral wall of the cylinder 1 is determined by the relative positional relationship between the fuel spray and the piston 2, and can be obtained from the fuel injection amount (time) and the fuel injection timing. it can. Therefore, the amount of the mixture of the suit increased by the splash of the fuel to the peripheral wall of the cylinder 1 can be obtained from the fuel injection amount and the fuel injection timing.

Therefore, in the configuration according to the second aspect,
The suit amount in the engine oil is calculated based on the engine speed, the fuel injection amount, and the fuel injection timing.

By determining the suit amount in consideration of the fuel injection timing in this way, it is possible to accurately calculate the suit mixing amount that is increased by the splash of the injected fuel to the cylinder peripheral wall as described above. Become. Therefore,
This makes it possible to more accurately grasp the amount of the suit in the engine oil, and thus to accurately detect the appropriate oil change timing.

Incidentally, even in diesel engines other than the direct injection type, the fuel injection timing may affect the combustion state of the injected fuel and the like, and may affect the degree of mixing of the suit into the engine oil. Therefore, for diesel engines other than the direct injection type, the engine speed,
Even when the oil change timing detecting device for a diesel engine configured to calculate the suit amount in engine oil based on the fuel injection amount and the fuel injection timing is applied, it is still possible to improve the detection accuracy of the oil change timing. become able to.

Further, in the above configuration, the suit amount can be accurately obtained without having to grasp in advance the correspondence between the engine rotational speed, the fuel injection amount, and the like and the suit mixing amount over the entire operation range of the engine. Therefore, application of the detection device is relatively easy. Therefore, according to the second aspect of the present invention, it is possible to relatively easily detect an appropriate engine oil replacement time.

Since the air-fuel ratio and the amount of EGR gas to be introduced (EGR rate) also influence the degree of mixing of the suit, it is preferable to calculate the suit amount in consideration of these factors. However, if these effects are sufficiently small and negligible, by using only the engine speed, the fuel injection amount, and the fuel injection timing for the calculation of the suit amount as in the above configuration, a sufficiently appropriate value can be obtained. The timing for changing the engine oil can be easily detected.

According to a third aspect of the present invention, there is provided the diesel engine oil replacement timing detecting device according to the second aspect, further comprising calculating a soot amount in the engine oil based on the air-fuel ratio. It is like that.

As described above, the degree of mixing of the suit into the engine oil largely depends on the engine rotation speed and the fuel injection amount, but the effects of the air-fuel ratio and the fuel injection timing are hard to ignore. .

In this regard, in the configuration according to the third aspect,
The suit amount is calculated in consideration of the influence of the air-fuel ratio and the fuel injection timing. Therefore, according to the third aspect of the present invention, it is possible to more accurately detect an appropriate engine oil replacement time.

According to a fourth aspect of the present invention, there is provided an oil exchange system for a diesel engine which detects a time to change the engine oil based on a calculation result of a suit amount contained in the engine oil of the diesel engine. In the timing detection device, the amount of the suit dissolved into the engine oil from the combustion gas is calculated based on the fuel injection amount and the air-fuel ratio, and is directly mixed into the engine oil by the scattering of the injected fuel on the piston top surface. The amount of the suit to be calculated is calculated based on the amount of fuel injected after the piston is located at the predetermined position, and the amount of the suit contained in the engine oil is calculated from both the calculated amounts of the suit. It is.

The suit is mixed into the engine oil in two ways, namely, the dissolution of the suit generated in the combustion gas and the direct mixing due to the scattering of the injected fuel on the piston top surface. The suit amount mixed in the former mode is
As described above, it depends on the amount of soot generated in the combustion gas and is affected by the fuel injection amount and the air-fuel ratio. The amount of the soot mixed in the latter mode depends on the amount of the scattered injected fuel, which can be obtained from the amount of fuel injected after the piston is located at the predetermined position. Therefore, in the above configuration, the amount of the suit mixed in both modes can be accurately obtained, so that the amount of the suit in the engine oil can be accurately grasped, and the timing for replacing the engine oil can be accurately detected.

[0032]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a diesel engine oil change timing detecting apparatus according to the present invention;

The diesel engine to which the oil change timing detecting device of the present embodiment is applied is a direct injection type vehicle-mounted diesel engine that directly injects fuel into a cylinder, and uses a common rail (accumulation type) system as the fuel injection device. Is adopted.

FIG. 2 shows a schematic configuration of an oil change timing detection device and a diesel engine to which the oil exchange timing detection device is applied, a hydraulic circuit configuration of a lubrication system of the engine, and the like. First, the configuration of the diesel engine will be described with reference to FIG.

As shown in FIG. 2, the diesel engine 10 includes an intake passage 11, an exhaust passage 12, a combustion chamber 16, and the like. A piston 14 is disposed in each cylinder 13 of the diesel engine 10 so as to be able to move up and down. At the center of the top surface 14a of the piston 14, a "hollow" (cavity) constituting the combustion chamber 16 is provided.
15 are formed. An injector 17 for injecting fuel is provided above the combustion chamber 16.

The common rail system includes a common rail 18 and the like, which is a fuel pressure accumulating chamber common to each cylinder 13, in addition to the injector 17. In the operation of the diesel engine 10, first, fuel stored in the fuel tank 18a is pumped out by the fuel pump 18b, pressurized to a high pressure, and stored in the common rail 18. The pressure of the fuel thus accumulated is applied to the injector 17 of each cylinder 13 connected to the common rail 18. A nozzle (not shown) that opens when the pressure behind the injector 17 reaches a predetermined high pressure and injects fuel is provided at the tip end of the injector 17. The start and end of fuel injection are determined by controlling the pressure behind the nozzle by an electromagnetic solenoid (not shown) provided inside the injector 17. Therefore, in such a common rail system, highly accurate fuel injection control independent of the rotation speed of the diesel engine 10 can be performed.

On the other hand, an intake throttle valve 22, which is opened and closed by a step motor 23 to vary the flow passage area of the intake passage 11, is provided upstream of the intake passage 11. Further upstream, an air flow meter 2 for detecting the amount of intake air flowing through the intake passage 11 is provided.
1, and an air cleaner 20 for purifying intake air are provided.

Now, this diesel engine 10 includes:
There is a lubricating portion 32 that requires lubrication of a bearing (not shown) such as a crankshaft or a camshaft, and a sliding surface between the cylinder 13 and the piston 14. As shown in FIG. 2, the lubricating engine oil supplied to the lubrication section 32 is stored in an oil pan 30 provided below the cylinder 13 in the diesel engine 10. Then, the engine oil in the oil pan 30 is pumped out by the oil pump 31 and sent out to each lubrication unit 32. The engine oil sent to each lubrication unit 32 is returned to the oil pan 30 again and circulated.

As the engine oil circulates in the diesel engine 10 in this manner, the suit generated with the combustion of the fuel is gradually mixed and deteriorated every time the engine oil is circulated,
Replacement is required. Therefore, the diesel engine 10 employs an oil change timing detection device for determining the degree of deterioration of engine oil and detecting the oil change timing. In addition, an instrument panel (not shown) at the driver's seat of the vehicle equipped with the engine 10 notifies a driver or the like that it is time to change the oil based on the detection result of the oil change time detecting device. An indicator 27 for instructing oil change is provided.

On the other hand, in such a diesel engine 10 and its oil change timing detecting device, the outputs of various sensors such as the air flow meter 21 are controlled by an electronic control unit which serves as a control system of the engine 10 and a diagnostic system thereof. (“ECU”) 26. The ECU 26 includes a step motor 23 for opening and closing the intake throttle valve 22 and an injector 1 for performing fuel injection.
In addition to controlling the driving of the indicator 7 and the like, a process relating to the detection of the oil change timing is executed, and the indicator 27 is turned on / off.

The ECU 26 includes, in addition to the air flow meter 21, the NE sensor 24 for detecting the rotational phase of the crankshaft 24a, which is the output shaft of the diesel engine 10, and the rotational speed of the crankshaft 24a.
Outputs of various sensors for detecting the operating state of the diesel engine 10, such as an accelerator sensor 25 for detecting the amount of depression of 5a and a fuel pressure sensor 19 for detecting the pressure of the fuel stored in the common rail 18, are input. And ECU
26 grasps the operating state of the diesel engine 10 based on the output results of these sensors,
Various controls of the engine 10 are executed by driving and controlling various actuators including the step motor 23 and the like.

As part of such engine control, the ECU
26 controls the fuel injection amount and the fuel injection timing based on the drive control of the injector 17. Next, such fuel injection amount and fuel injection timing control will be described.

First, the ECU 26 calculates the fuel injection amount and the fuel injection timing (start timing of fuel injection) according to the operation state of the diesel engine 10 based on the output results of various sensors such as the NE sensor 24 and the accelerator sensor 25. I do. Further, the fuel injection time during which fuel can be injected in accordance with the calculated fuel injection amount, that is, the injector 17
Is calculated based on the engine speed at that time detected by the NE sensor 24 and the fuel pressure sensor 19 and the fuel pressure in the common rail 18.

The ECU 26 calculates the timing of starting the fuel injection from the injector 17 (rotational phase of the crankshaft) and the timing of terminating the injection from these calculation results, and sets the injector 17 according to the timing. Drive control. Thus, an appropriate amount of fuel is injected from the injector 17 at an appropriate time according to the operating state of the diesel engine 10.

In this diesel engine 10,
By adopting the above common rail system and performing fine fuel injection control, and also performing intake air flow control,
The aim is to improve emissions and fuel efficiency. For this purpose, the intake passage 11 is provided with an intake throttle valve 22 driven by a step motor (23) capable of finely adjusting the opening degree as described above, and the amount of intake air is detected by the air flow meter 21. And ECU
26 is a step motor 22 according to the engine operating state.
Is driven to finely control the amount of intake air.

On the other hand, the ECU 26 determines the air-fuel ratio in the combustion chamber 16 based on the fuel injection amount calculated for controlling the driving of the injector 17 and the intake air amount detected by the air flow meter 21. It is calculated.

In this embodiment, as described above, the EC
U26 executes a process related to the detection of the engine oil replacement timing in addition to the process related to the engine control such as the fuel injection control. Subsequently, a process related to the detection of the oil replacement time will be described with reference to FIGS.

In this oil change timing detecting device, the oil is mixed into the engine oil for a predetermined calculation period (for example, one second) based on the operating state of the diesel engine such as the engine speed, the fuel injection amount, the air-fuel ratio, and the fuel injection timing. The amount of the suit in the engine oil is obtained by calculating the amount of the suit to be performed (the mixed amount of the suit) as needed, and integrating the calculation results. Then, when the amount of the suit determined in this way exceeds a predetermined limit value, the engine oil replacement time is detected.

First, the details of the method of calculating the mixed amount of the suit during the predetermined calculation period in the present embodiment will be described. The manner in which the suit is mixed into the engine oil is roughly classified into the following two aspects. One is that a part of the suit generated by burning the fuel is mixed into the engine oil such as the peripheral wall of the cylinder 13, and the other is that the suit overflows from the cavity 15 at the time of injection and burns while burning. This is a mixture in a mode of being sprayed into the engine oil on the 13th peripheral wall.

The amount of the suit mixed in the former embodiment is proportional to the amount of the suit generated during combustion. This suit generation amount is determined by the amount of fuel to be burned, that is, the fuel injection amount, and the suit conversion rate of the fuel during combustion. In this case, the smaller the ratio of the air in the combustion chamber 16 to the injected fuel, that is, the richer the air-fuel ratio, the more incomplete combustion of the fuel occurs, and the more the suit is generated.

Therefore, the suit mixing amount in the former mixing mode can be determined based on the fuel injection amount and the air-fuel ratio. In the present embodiment, the suit mixing amount S1 in the engine oil in the engine oil in the predetermined calculation period (1 second) is calculated by the following equation (b).

S 1 = Gfin · f {ABYF} · NE · CY / 2 (Equation (b)) Here, “Gfin” represents the fuel injection amount, “NE” represents the engine rotation speed [every second], and “CY” represents “CY”. The number of cylinders of the diesel engine 10 is shown. Also, "f
“{ABYF}” is a function of the air-fuel ratio ABYF, and its value is proportional to the fuel conversion rate at the time of combustion by the air-fuel ratio ABYF. The value of the function f {ABYF} increases as the air-fuel ratio ABYF becomes richer.

FIG. 3 shows the relationship between the suit mixing amount S1 and the air-fuel ratio ABYF in such a mixing mode. FIG. 3
As shown in the figure, the suit mixing amount S1 in this mixing mode is
As the air-fuel ratio ABYF becomes richer (smaller value), it increases. By the way, when the suit is mixed only in such an aspect, the generated suit is mostly discharged together with the exhaust gas, so that the mixed amount of the suit is relatively small.

On the other hand, the latter mode, that is, cavity 1
The mixed amount of the suit due to the overflow of the injected fuel from No. 5 changes according to the position of the piston 14 during the fuel injection period. For example, as shown in FIG. 1A, if fuel injection is performed during a period in which the piston 14 is located upward, most of the injected fuel remains in the cavity 15 of the piston 14.
Suit mixing in such a manner as to be directly sprayed on the peripheral wall of the cylinder 13 hardly occurs.

However, when the fuel injection timing (injection start timing) is retarded or the fuel injection amount (injection time) is increased,
As shown in FIG. 1B, if fuel injection is performed even after the piston 14 has moved downward to some extent, the injected fuel will not be able to fit in the cavity 15. Part of the fuel injected from the injector 17 scatters or is directly sprayed on the top surface 14a of the piston 14, and directly mixes into the engine oil on the peripheral wall of the cylinder 13 while burning. .

As shown in FIG. 1B, the amount of the suit mixed in this manner is such that the injected fuel is
The fuel injection amount can be grasped from the fuel injection amount until the injection is completed after the overflow from 5 is reached.

In the present embodiment, the amount S2 of the suit mixed into the engine oil in the latter calculation mode during the predetermined calculation period (1 second) is calculated by the following equation (c). S2 = β · Gfin · (Te−α) / (Te−Ts) · NE · CY / 2 [However, S2> 0] Expression (c) Here, “Te” represents the injection end timing [° CA]. , "T
“s” indicates the injection start timing [° CA].
Further, “α” is a timing at which the fuel injected from the injector 17 overflows from the cavity 15 [° C.
A]. Further, “β” is a predetermined constant indicating a ratio of the amount of the suit mixed into the engine oil in the latter mode with respect to the amount of the fuel overflowing from the cavity 15.

By the way, in the diesel engine 10 to which the present embodiment is applied, when the injection end time Te is after “20 ° CA” from the top dead center of the corresponding cylinder, the injected fuel overflows from the cavity 15. The constant “α” is set to “20 ° CA”.

FIG. 4 shows the relationship between the suit mixing amount S2 and the injection end timing Te in such a mixing mode. As shown in FIG. 4, the suit mixing amount S2 in this mixing mode
Increases as the amount of fuel injected after “α ° CA” increases after the injection end timing Te is retarded.

FIG. 5 is a flowchart showing a "suit amount calculation routine" used in the present embodiment. This calculation routine is periodically executed by the ECU 26 (FIG. 1) every predetermined calculation period (one second).

Now, when the processing shifts to this routine, E
First, in step 110, the CU 26 calculates the expression (b)
Accordingly, the suit mixing amount S1 in the former mixing mode during the predetermined calculation period is calculated based on the engine speed NE, the fuel injection amount Gfin, and the air-fuel ratio ABYF.

In the following step 120, according to the above equation (c), the suit mixing amount S2 in the latter mixing mode during the predetermined calculation period is determined by the engine rotation speed NE,
The calculation is performed based on the fuel injection amount Gfin and the fuel injection timing (the injection start timing Ts and the injection end timing Te).

Then, in the following step 130,
The calculated suit mixing amounts S1 and S2 are converted to the suit amount S
Add to T. In this way, in this routine, the suit mixing amounts S1 and S2 in each of the above-described mixing modes are calculated as needed at each predetermined calculation period, and the calculation results are integrated to calculate the suit amount ST in the engine oil. ing. The suit amount ST is cleared to “0” by operating the reset switch when the engine oil is changed.

Further, in the present embodiment, the degree of deterioration of the engine oil is determined based on the so calculated amount of the suit, and the oil replacement time is detected. FIG.
5 is a flowchart showing an “oil change timing detection routine” adopted in the present embodiment. This detection routine is executed by the ECU 26 (FIG. 1) for a predetermined time (1
Every second).

When the processing shifts to this routine, E
First, at step 200, the CU 26 determines whether or not the suit amount ST in the engine oil calculated by the processing according to the above “suit amount calculation routine” is less than a predetermined value γ1 that is slightly smaller than a predetermined limit value γ2 that requires oil change. Judge. If the suit amount ST is less than the predetermined value γ1 (step 200: YES), the process once exits this routine. On the other hand, if the suit amount ST in the engine oil is equal to or more than the predetermined value γ1 (step 200: NO), the process proceeds to step 210, and whether the suit amount ST in the engine oil is less than the predetermined limit value γ2. Determine whether or not.

If the suit amount exceeds the predetermined limit value γ2 (step 210: YES), the indicator 27 is turned on in step 220 to notify the driver or the like that the oil change time has come. On the other hand, if the suit amount ST is less than the predetermined limit value γ2 (γ1 <= ST <γ2) (step 210: YES), the indicator 27 is flashed in step 230 to notify that the oil change time is approaching. .

As described above, in the present embodiment, the timing of changing the engine oil is detected based on the calculation result of the suit amount ST contained in the engine oil, and the indicator 27 lights or blinks to notify the driver or the like. To notify.

According to the above-described apparatus for detecting oil change timing of a diesel engine according to the present embodiment, the following effects can be obtained. (1) In the above embodiment, the suit amount in the engine oil is calculated based on the engine rotation speed, the fuel injection amount, and the air-fuel ratio, and the timing of changing the engine oil is detected based on the calculation result. . Therefore, the amount of the suit in the engine oil can be obtained in consideration of the influence of the air-fuel ratio on the combustion mode of the injected fuel, so that the time for changing the oil can be more appropriately detected.

(2) In the above embodiment, the suit amount in the engine oil is calculated based on the engine speed, the fuel injection amount, and the fuel injection timing, and the engine oil replacement timing is detected based on the calculation result. I am trying to do it. Therefore, the amount of the suit in the engine oil can be obtained in consideration of the influence of the fuel injection timing, so that the oil replacement timing can be accurately detected.

(3) In the above embodiment, in the direct injection type diesel engine in which the degree of mixing of the suit into the engine oil changes greatly depending on the position of the piston during the fuel injection period, the engine speed, the fuel injection amount and the fuel The suit amount in the engine oil is calculated based on the injection timing. Therefore, even in such a direct injection type diesel engine, it is possible to detect an appropriate oil change timing in consideration of a change in the degree of suit mixing as described above.

(4) In the above embodiment, the suit amount in the engine oil can be accurately determined without previously obtaining the correspondence between the engine operating state and the degree of mixing of the suit in the entire operation range of the diesel engine 10. You can ask. Therefore, it is possible to relatively easily detect an appropriate engine oil replacement time.

(Other Embodiments) In the above embodiment, the amount of soot mixed into the engine oil during the predetermined calculation period is calculated using the above equations (b) and (c), and the calculation result is calculated. Although the suit amount was obtained by integrating, the suit amount calculation mode is arbitrary, and the point is that one or both of the air-fuel ratio and the fuel injection timing,
If the calculation is performed based on the engine speed and the fuel injection amount, it is possible to detect an appropriate oil change timing in consideration of the influence of the air-fuel ratio and the fuel injection timing on the degree of mixing of the suit.

Further, when parameters other than the engine speed, the fuel injection amount, the air-fuel ratio, and the fuel injection timing, such as the EGR rate, have a nonnegligible effect on the degree of mixing of the suit, the parameters are further added. By calculating the above-mentioned suit amount in consideration of the above, a more accurate suit amount in the oil can be predicted.

Next, a description will be given of a modification of the manner of calculating the suit amount. In the above-described embodiment, the suit amount S1 in which a part of the suit generated by combustion is mixed into the engine oil such as the peripheral wall of the cylinder 13 is calculated based on the above equation (b). In this equation (b), the suit amount S1 is calculated by multiplying the total amount of fuel injection per predetermined time by the fuel suit conversion rate calculated according to the air-fuel ratio. Further, the total amount of fuel injection per predetermined time is obtained from the engine speed and the fuel injection amount.

As described above, the influence of the air-fuel ratio is basically the dominant factor in determining the suit amount S1 in the mixing mode, but the influence of other factors cannot be neglected in some cases. Sometimes.

For example, it has been confirmed by the inventors that the fuel injection end timing has a considerable effect on the suit conversion rate. Therefore, in this case, f {ABYF} in the above equation (b) is a function including the injection end timing in addition to the air-fuel ratio, so that the influence of the injection end timing is also reflected. That is, here, the value of f {ABYF} of the above equation (b) is obtained using the calculation map of the air-fuel ratio and the injection end timing illustrated in FIG. As shown in the figure, f {ABYF} is set to a larger value as the injection end timing is more retarded or the air-fuel ratio is richer. The correlation between the air-fuel ratio, the injection end timing, and f {ABYF} can be obtained by an experiment, a simulation using a physical model, or the like.

Furthermore, when other factors such as the EGR rate have a non-negligible effect on the fuel conversion rate, the above f {ABYF} is made to be a function including these factors, and thus, such a factor is obtained. The influence can be reflected on the suit amount S1.

On the other hand, in the above-described embodiment, the soot amount S2 which overflows from the inside of the cavity 15 at the time of injection and is sprayed into the engine oil on the peripheral wall of the cylinder 13 while burning is calculated based on the above equation (c). are doing. Here, the suit amount S2 is obtained from a value obtained by multiplying the amount of fuel injected after the time α at which overflow from the cavity occurs by a predetermined constant β indicating the suit conversion rate of such fuel. That is, in the above-described embodiment, the suit amount S2 in such a mixing mode is obtained on the premise that it is proportional to the amount of fuel injected after the timing α.

Thus, the suit amount S can be accurately determined to some extent.
2 can be predicted, but strictly speaking, various factors have a complicated influence on the suit amount S2, and there is a limit in improving the prediction accuracy based on the simple proportional relationship as described above.

For example, even after the predetermined time α,
Piston top surface 1 according to the position of piston 14 at the time of injection
The ratio of the fuel reflected at 4a and adhering to the peripheral wall of the cylinder 13 changes. In addition, depending on the combustion state in the combustion chamber 16 at the time of injection, the soot conversion rate of the fuel attached to the peripheral wall of the cylinder 13 also changes.

Therefore, here, the coefficient β in the above equation (c) is not taken as a constant, but the coefficient β is obtained as a function of the injection end timing, so that such an effect is reflected in the suit amount S2. That is, here, the coefficient β is obtained using the calculation map of the injection end timing as exemplified in FIG. Here, the correlation between the injection end timing and the coefficient β can also be obtained by an experiment, a simulation using a physical model, or the like. Thus, the suit amount S2 can be obtained more accurately.

If other factors have a non-negligible effect, the effect of such factors can be reflected in the suit quantity S2 by setting the coefficient β as a function including those factors.

The present invention described above can be further modified and implemented as follows. In the above-described embodiment, the suit amount in the engine oil is calculated based on the air-fuel ratio and the fuel injection timing in addition to the engine speed and the fuel injection amount, but the influence of the fuel injection timing on the degree of mixing of the suit. Is small enough,
If it is within a negligible range, the engine oil replacement time can be properly detected even if the suit amount is calculated based only on the engine speed, the fuel injection amount, and the air-fuel ratio.

If the effect of the air-fuel ratio on the suit amount in the engine oil is sufficiently small and within the negligible range, the suit amount is calculated based only on the engine speed, fuel injection amount and fuel injection timing. In this case, the engine oil replacement time can be properly detected.

In the above embodiment, the diesel engine 10 having the common rail system as the fuel injection device
Although the case where the oil change timing detecting device according to the present invention is applied to the present invention has been described, the same detecting device as in the above embodiment can be applied to a diesel engine having a fuel injection device other than the common rail system.
In this case, the same effect as in the above embodiment can be obtained.

In the above embodiment, the case where the oil replacement timing detecting device according to the present invention is applied to a direct injection type diesel engine has been described. However, the present embodiment is also applicable to other diesel engines. By applying a detection device according to the above, it is possible to obtain an effect similar to or similar to that of the above embodiment.

Next, technical ideas other than those described in the claims which can be understood from the above embodiment will be listed below. (A) In the oil change timing detection device for a diesel engine according to claim 1, when calculating the suit amount in the engine oil, the engine in a predetermined calculation period based on the engine rotation speed, the fuel injection amount, and the air-fuel ratio. An oil change timing detection device for a diesel engine, wherein a suit mixing amount in oil is sequentially calculated, and the calculation result is integrated to calculate a suit amount in the engine oil.

In the above configuration, the suit mixing amount is sequentially calculated based on the engine rotation speed, the fuel injection amount, and the air-fuel ratio for each predetermined calculation period, and the calculation result is integrated to calculate the suit amount in the engine oil. I have to. Therefore, a change in the degree of mixing of the suit according to the engine operating state can be more accurately reflected.

(B) In the diesel engine oil change timing detecting device according to claim 2, when calculating the amount of the suit in the engine oil, a predetermined amount is determined based on the engine speed, the fuel injection amount and the fuel injection timing. An oil change timing detecting device for a diesel engine, wherein a suit mixing amount in engine oil during a calculation period is sequentially calculated, and the calculation result is integrated to calculate a suit amount in the engine oil. .

In the above configuration, the suit mixing amount is sequentially calculated based on the engine speed, the fuel injection amount, and the fuel injection timing for each predetermined calculation period, and the calculation result is integrated to calculate the suit amount in the engine oil. Like that. Therefore, a change in the degree of mixing of the suit according to the engine operating state can be more accurately reflected.

(C) In the diesel engine oil change timing detecting device according to claim 3, when calculating the amount of the suit in the engine oil, the engine speed, the fuel injection amount, the fuel injection timing, and the air-fuel ratio are calculated. And calculating the amount of the suit in the engine oil by sequentially calculating the amount of the mixture in the engine oil during the predetermined calculation period based on the calculated amount. Replacement time detector.

In the above configuration, the suit mixing amount is sequentially calculated based on the engine speed, the fuel injection amount, the air-fuel ratio, and the fuel injection timing for each predetermined calculation period, and the calculation result is integrated to integrate the suit amount in the engine oil. Is calculated. Therefore, a change in the degree of mixing of the suit according to the engine operating state can be more accurately reflected.

(D) In the diesel engine oil change timing detecting device according to claim 2 or 3, or (b) or (d), the diesel engine employs a direct injection system for directly injecting fuel into a cylinder. An oil change timing detection device for a diesel engine, which is a diesel engine.

As described above, in the direct injection type diesel engine, the position of the piston during the fuel injection period may greatly affect the degree of mixing of the suit into the engine oil. In such a direct-injection diesel engine, by using the fuel injection amount and the fuel injection timing in calculating the amount of the suit in the engine oil, it is possible to detect an appropriate oil change timing in consideration of the above effects. Become.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a fuel injection mode in a direct injection type diesel engine.

FIG. 2 is a schematic diagram schematically showing an entire structure of an embodiment of a diesel engine oil change timing detection device according to the present invention.

FIG. 3 is a schematic diagram showing a relationship between an air-fuel ratio and a suit mixing amount in the embodiment.

FIG. 4 is a schematic diagram showing a relationship between an injection end time and a suit mixing amount in the embodiment.

FIG. 5 is a flowchart showing a procedure for calculating a suit amount in engine oil according to the embodiment;

FIG. 6 is an exemplary flowchart showing a processing procedure relating to detection of an oil replacement time according to the embodiment;

FIG. 7 is a schematic diagram illustrating an example of a calculation map according to another embodiment.

FIG. 8 is a schematic diagram illustrating an example of a calculation map according to another embodiment.

[Explanation of symbols]

10: diesel engine, 14: piston, 15: cavity, 16: combustion chamber, 17: injector, 21 ...
Air flow meter, 22 intake throttle valve, 23 step motor, 24 NE sensor, 26 electronic control unit (EC
U), 27 ... indicator.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsugu Yanaka 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Masao Kimura 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation ( 72) Inventor Hiroshi Iida 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Masaru Higashiya 1 Toyota Town Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Masao Miyazaki Aichi Prefecture 1 Toyota Town, Toyota City Toyota Motor Corporation (72) Inventor Yasuhide Itai 1 Toyota Town Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Yukio Yoshida 1 Toyota Town Toyota City, Aichi Prefecture Toyota Automobile Co., Ltd.

Claims (4)

[Claims] 1. A diesel engine oil replacement timing detecting device for detecting a replacement timing of an engine oil based on a calculation result of a suit amount contained in the engine oil of the diesel engine. An oil change timing detecting device for a diesel engine, wherein a suit amount in the engine oil is calculated based on a fuel ratio. 2. A diesel engine oil replacement timing detecting device for detecting a replacement timing of an engine oil based on a calculation result of a suit amount contained in the engine oil of the diesel engine. An oil change timing detecting device for a diesel engine, wherein a suit amount in the engine oil is calculated based on an injection timing. 3. The diesel engine oil change timing detecting device according to claim 2, wherein the amount of the suit in the engine oil is further calculated based on an air-fuel ratio. Replacement time detector. 4. A diesel engine oil replacement timing detecting device for detecting a replacement timing of an engine oil based on a calculation result of a suit amount contained in the engine oil of the diesel engine. While calculating the amount of melted suit based on the fuel injection amount and air-fuel ratio,
The amount of soot directly mixed into the engine oil due to the scattering of the injected fuel on the top surface of the piston is calculated based on the amount of fuel injected after the piston is located at a predetermined position. An oil change timing detecting device for a diesel engine, wherein a suit amount contained in the engine oil is calculated from the suit amount.