JP2002174137A - Engine oil temperature estimating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate the temperature of an engine oil by utilizing an existing sensor in use for engine or transmission control without requiring a special engine oil temperature sensor. SOLUTION: This engine oil temperature estimating method comprises using engine speed detecting means for detecting an engine speed and vehicle speed detecting means for detecting a vehicle speed. A value obtained by multiplying a correcting coefficient to be changed depending on a value for an intake pipe pressure by an oil temperature map value found by the engine speed detected by the engine speed detecting means and the vehicle speed detected by the vehicle speed detecting means is set as a target oil temperature and the engine oil temperature is estimated from the target oil temperature. Otherwise, the engine oil estimating method comprises the engine speed detecting means for detecting the engine speed and gear position detecting means for detecting a gear position for a transmission. A value obtained by multiplying a correcting coefficient to be changed depending on a value for an intake pipe pressure by an oil temperature map value found by the engine speed detected by the engine speed detecting means and the vehicle speed detected by the gear position detecting means for the transmission is set as a target oil temperature and the engine oil temperature is estimated from the target oil temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for estimating an engine oil temperature, and particularly to a method for estimating an engine oil temperature by using an existing sensor used for engine or transmission control without specially providing an engine oil temperature sensor. And a method for estimating the engine oil temperature.

[0002]

2. Description of the Related Art In general, when controlling an engine or the like in a vehicle, there is a vehicle which measures an engine oil temperature or the like using a temperature sensor and performs control using the measured temperature as one piece of control information.

Until now, in addition to those having the above-mentioned temperature sensors, there are also those which do not use temperature sensors having a relatively high unit price and obtain numerical values by using an arithmetic measure.

[0004] As a method of estimating the engine oil temperature, there is a method disclosed in Japanese Patent Application Laid-Open No. 8-177599. The method and the apparatus for estimating the temperature of vehicle equipment disclosed in this publication include:
The slip loss of the torque converter is calculated by a neutral network operation using the intake air pressure of the engine, the rotation speed of the engine output shaft, and the turbine rotation speed of the torque converter as input variables, and the rotation speed of the engine output shaft and the shift position of the automatic transmission are calculated. Calculate the agitation loss of the automatic transmission by a neutral network calculation with the input variables as the input variables, and calculate the cooling amount of the automatic transmission by the neutral network calculation with the vehicle speed and the outside air temperature as the input variables.
Estimating the temperature of the shift control oil by neutral network calculation using slip loss, stirring loss and cooling amount as input variables,
At this time, the past temperature estimation value is added to the input variable, and the temperature of a tangible object (engine cooling water, shift control oil, catalyst, etc.) equipped in the vehicle is accurately estimated without the need for a temperature sensor.

[0005] Another example is disclosed in Japanese Patent Application Laid-Open No. 10-227235. The valve timing control device for an internal combustion engine disclosed in this publication provides a valve timing in accordance with an initial oil temperature replacing the cooling water temperature at the time of starting the internal combustion engine, the engine speed, and other loads representing the operating state of the internal combustion engine. The oil temperature of the hydraulic oil of the control mechanism is estimated and obtained by adding the initial oil temperature, the total calorific value by combustion in the cylinder, and the total frictional heat by the cylinder / piston, etc., and a hydraulic valve timing control mechanism is used. The oil temperature is accurately estimated without newly providing an oil temperature sensor or the like.

[0006] Furthermore, there is one disclosed in JP-A-2000-73794. The variable valve mechanism control device for an internal combustion engine disclosed in this publication discloses a valve timing and / or at least one of an intake valve and an exhaust valve of the internal combustion engine.
Or a variable valve mechanism that controls the lift amount by hydraulic pressure,
Abnormality determination means for determining the presence or absence of an abnormality in the variable valve mechanism based on the differential state of the variable valve mechanism; oil temperature determination means for determining the temperature of hydraulic oil for generating hydraulic pressure (hereinafter referred to as “oil temperature”); Erroneous determination prevention means for prohibiting abnormality determination of the variable valve mechanism by the abnormality determination means when the oil temperature determined by the oil temperature determination means is lower than a predetermined temperature, and lowering the oil temperature (viscosity increase of hydraulic oil) Erroneous determination of an operation delay of the variable valve timing mechanism as an abnormality of the variable valve timing mechanism is prevented.

[0007]

By the way, in the prior art, the oil pressure of the engine decreases as the engine oil temperature increases, and the oil pressure decreases.

In particular, when the engine is idling at a low engine speed, the oil pressure becomes too low, which causes a problem that the engine may be hindered or a warning lamp for warning of a decrease in the oil pressure may be turned on.

In order to avoid such a situation, there is a method of employing a pump having a large discharge amount of the engine oil pump.

[0010] However, when the size of the engine oil pump is increased, there is a disadvantage that the mechanical loss of the engine is increased and the fuel efficiency and output are deteriorated.

[0011] Further, in the case where the engine oil temperature is measured by a temperature sensor, the unit price of the temperature sensor is relatively high, which is economically disadvantageous, and there is a demand to minimize the use of the temperature sensor.

[0012]

SUMMARY OF THE INVENTION In order to eliminate the above-mentioned disadvantages, the present invention provides an engine oil temperature having engine speed detecting means for detecting engine speed and vehicle speed detecting means for detecting vehicle speed. In the estimating method, a correction coefficient that changes according to the value of the intake pipe pressure is added to an oil temperature map value obtained from the engine speed detected by the engine speed detecting means and the vehicle speed detected by the vehicle speed detecting means. The multiplied value is set as a target oil temperature, and the engine oil temperature is estimated from the target oil temperature.

Further, in an engine oil temperature estimating method comprising an engine speed detecting means for detecting an engine speed and a gear position detecting means for detecting a gear position of a transmission, the engine speed is detected by the engine speed detecting means. A target oil temperature is set as a value obtained by multiplying an oil temperature map value obtained from the engine speed and the vehicle speed detected by the gear position detecting means of the transmission by a correction coefficient that changes according to the value of the intake pipe pressure, The engine oil temperature is estimated from the target oil temperature.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION
When estimating the engine oil temperature, the oil temperature map value obtained from the engine speed detected by the engine speed detecting means and the vehicle speed detected by the vehicle speed detecting means changes according to the value of the intake pipe pressure. The value obtained by multiplying the target oil temperature is set as the target oil temperature, and the engine oil temperature is estimated from the target oil temperature.

Further, when estimating the engine oil temperature, an intake air temperature map value obtained from the engine speed detected by the engine speed detecting means and the vehicle speed detected by the gear position detecting means of the transmission is used as an intake air temperature. A value multiplied by a correction coefficient that changes according to the pipe pressure value is set as a target oil temperature, and an engine oil temperature is estimated from the target oil temperature.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 to FIG. 3 show a first embodiment of the present invention. In FIG. 2, 2 is an engine mounted on a vehicle (not shown), 4 is a cylinder block, 6 is a cylinder head, 8 is a head cover, 10 is a piston, 12 is a combustion chamber, 14 is an intake port, 16 is an exhaust port, and 18 is An intake valve 20 is an exhaust valve.

The engine 2 has an air intake passage 32 communicating with the intake port 14 by sequentially connecting an air cleaner 22, an intake pipe 24, a throttle body 26, a surge tank 28, and an intake manifold 30 as an intake system. A throttle valve 34 is provided in the intake passage 32 of the throttle body 26.

In the engine 2, an exhaust manifold 36, an exhaust pipe 38, and a catalytic converter 40 are sequentially connected as an exhaust system, and an exhaust passage 4 communicating with the exhaust port 16 is provided.
2 are provided. In the catalytic converter 40, a catalyst 44 is provided.
Is provided.

The engine 2 has a head cover 8 and a PC.
The PCV valve 46 is provided with a V valve 46 attached thereto.
A first blow-by gas passage 48 is provided for communicating the inside of the head cover 8 with the intake passage 32 of the surge tank 28 through the second passage, and a second blow-by gas is provided for communicating the inside of the head cover 8 with the intake passage 32 upstream of the throttle body 26. A passage 50 is provided.

Further, the engine 2 has a fuel injection valve 52 provided in the cylinder head 6 so as to be directed toward the combustion chamber 12. The fuel injection valve 52 is connected to a fuel tank 56 by a fuel supply passage 54. And the fuel tank 5
A fuel pump 58 for supplying fuel to the fuel supply passage 54 is provided in the inside 6. A fuel filter 60 and a pressure regulator 62 for adjusting the fuel pressure are provided in the fuel supply passage 54 in the fuel tank 56.

The fuel tank 56 has an evaporation passage 64
Is connected through a two-way check valve 66. The other end of the evaporation passage 64 communicates with the canister 68. One end of a purge passage 70 communicates with the canister 68. The other end of the purge passage 70 communicates with the intake passage 32 upstream of the throttle valve 34.

The engine 2 bypasses the throttle valve 34 and connects the intake passage 32 of the throttle body 26 and the intake passage 32 of the surge tank 28 to a bypass passage 72.
Is provided. A bypass air amount control valve (also referred to as an “ISC valve”) 74 for adjusting a bypass air amount is provided in the middle of the bypass passage 72.

The engine 2 is provided with an ignition coil 76 for causing a spark plug (not shown) to ignite, and a crank angle sensor 78 functioning as an engine speed detecting means for detecting a crank angle and an engine speed. A water temperature sensor 80 for detecting a water temperature is provided, a throttle sensor 82 for detecting a throttle opening of the throttle valve 34 is provided, and a pressure sensor 84 for detecting an intake pipe pressure of the intake passage 32 is connected to the surge tank 28.
And an air-fuel ratio detecting means for detecting an air-fuel ratio in the exhaust passage 42, for example, an O2 sensor 86 for detecting the oxygen concentration in the exhaust gas, and a vehicle speed sensor 88 as a vehicle speed detecting means for detecting the vehicle speed. A knock sensor 90 for detecting knocking of the engine 2 is provided, and a hydraulic pressure sensor 92 for detecting engine oil pressure is provided.

The fuel injection valve 52, fuel pump 58, bypass air amount control valve 74, ignition coil 76, crank angle sensor 78, water temperature sensor 80, throttle sensor 82, pressure sensor 84, O2 sensor 86, vehicle speed sensor 88, knock The sensor 90 and the oil pressure sensor 92
It is connected to control means 96 constituting a fuel injection control device 94 having an engine oil temperature estimation system. In addition,
Reference numeral 98 denotes a battery.

The control means 96 controls the oil speed obtained from the engine speed detected by the crank angle sensor 78 as the engine speed detecting means and the vehicle speed detected by the vehicle speed sensor 88 as the vehicle speed detecting means. It has a function of setting a value obtained by multiplying the temperature map value by a correction coefficient that changes according to the value of the intake pipe pressure as a target oil temperature, and estimating an engine oil temperature from the target oil temperature.

More specifically, the control for estimating the engine oil temperature by the control means 96 will be described. The starting conditions for the control for estimating the engine oil temperature are when the following two items are satisfied. (1) Complete explosion mode (2) Water temperature TWN ≧ predetermined water temperature KTWOILH (80 degrees)
[KTWOILHH (5 degrees)] KTWOILHH: Hysteresis component

The control contents of the control means 96 in the estimation control of the engine oil temperature will be described. As shown in FIG. 3, when the above-mentioned items (1) and (2) of the starting conditions are respectively satisfied, The estimated oil temperature THOIL is calculated for each TMTOIL # (1000 ms).

That is, the target oil temperature THOIL is obtained by the following equation: TTHOLIL = kthoinv · kthoild kthoinv: oil temperature map value kthoild: correction coefficient 1

At this time, the oil temperature map value kthoinv
Is obtained from an oil temperature map MAPHOIL (HNDATA / VSP) including the engine speed detected by the crank angle sensor 78 as the engine speed detecting means and the vehicle speed detected by the vehicle speed sensor 88 as the vehicle speed detecting means. .

Further, an intake pipe map TKOILL which changes the correction coefficient kthoild according to the value of the intake pipe pressure.
D (PMTP).

Then, the estimated oil temperature THOIL is calculated by the equation THOIL = toilold + (THOIL-toi
(old) · kdeltoil toilold: previous value kdeltoil: correction coefficient

The setting of the correction coefficient kdeltoil is performed as follows. (1) When TTHOLIL-toilold ≧ kdeltoil = KDELOILU # (0.05) (2) When TTHOLIL-toilold <kdeltoil = KDELOILD # (0.02)

The initial value of the estimated oil temperature THOIL is set to TOILH0 # (90 degrees).

Further, the estimated oil temperature THOIL is stored in a backup even after the ignition is turned off.

The condition for canceling the oil temperature estimation control is as follows: water temperature TWN <predetermined water temperature KTWOILL (70 degrees) [KT
WOILLH (5 degrees)] KTWOILLH: Set for hysteresis.

When the condition for canceling the oil temperature estimation control is satisfied, the estimated oil temperature THOIL is set to THOIL = TOILH0 # (90 degrees).

The control means 96 controls the estimated oil temperature THOIL
When the oil temperature is higher than a predetermined value (120 degrees) which is the set oil temperature, the idle speed is set high, for example, 1000 rpm. By setting the idling speed high, it is possible to secure a hydraulic pressure necessary for idling and a sufficient hydraulic pressure so that the hydraulic warning light does not light.

Here, the bypass air amount control valve (“I
Explaining the ISC control of the “SC valve” 74, the activation condition of the ISC control of the bypass air amount control valve 74 is “always”.

Then, the IS of the bypass air amount control valve 74 is
To describe the control contents in the C control, the lower limit value NSETMN of the ISC control is set as follows. NSETMN ≧ NSET0

The lower limit value NSETMN of the ISC control
Is controlled to rise or fall in the following situations. (1) Raising and lowering of lower limit value NSETTMN depending on load condition (Description is omitted because it is a known technology.) (2) Raising and lowering of lower limit value NSETMN by a CVT vehicle creep force determination idle-up request (known technology. Therefore, the description is omitted.) (3) The lower limit value NSETMN based on the estimated oil temperature THOIL rises and falls.

At this time, the lower limit value NSETMN based on the estimated oil temperature THOIL increases because the estimated oil temperature THOIL becomes THOIL ≧ THOILHI # (120 degrees) [THOI
LHIH (5 degrees)], NSET0 is set as the initial value and KNLIFTD3 #
(1000rpm), lower limit NSETMN to KTL
Increase by 12.5 rpm every FTUP3 # (10 ms).

The lower limit N based on the estimated oil temperature THOIL
The lowering of SETMN reduces the lower limit NSETN to the lower limit NS.
From ETMN to the initial value NSET0, KTLFTDN3
Decrease by 12.5 rpm every # (1000 ms).

Next, the operation will be described with reference to the control flowchart of FIG.

When the control program is started (102), the engine speed and the vehicle speed detected by the crank angle sensor 78, which is the engine speed detecting means, are controlled by the control means 96 for estimating the engine oil temperature. An oil temperature map value is obtained from an oil temperature map MAPHOIL (HNDATA / VSP) including the vehicle speed detected by the vehicle speed sensor 88 (104).

Then, the target oil temperature THOIL is obtained from the equation TTHOLIL = kthoinv · kthoild kthoinv: oil temperature map value kthoild: correction coefficient 1 (based on the intake pipe pressure value) (106), and the obtained target oil temperature is taken as the engine oil temperature. Estimation (108) is performed to obtain an estimated oil temperature THOIL.

Thereafter, the estimated oil temperature TH which is the engine oil temperature
It is determined (110) whether or not the OIL is equal to or more than a predetermined value (120 degrees).

If the determination (110) is YES, the idle speed is increased, for example, 1000 rpm.
Is set (112), and the process proceeds to the return (118) described later. If the determination (110) is NO,
The estimated oil temperature THOIL, which is the engine oil temperature, is a predetermined value (12
(0 degree) is determined (114).

When the determination (114) is NO, the process directly proceeds to the return (118), and when the determination (114) is YES, the idling speed is set to a low value, for example, 800 rpm (116). , Return (118).

Thus, the existing sensor used for engine or transmission control can be used without specially providing an engine oil temperature sensor.
This can contribute to system simplification and cost reduction.

When the estimated oil temperature THOIL is higher than a predetermined oil temperature (120 degrees), the control means 96 increases the idle speed by, for example, 100
By setting the rotation speed to 0 rpm, an oil pump that is smaller than the conventional one and has a smaller discharge rate can be used satisfactorily. By using a smaller oil pump, mechanical loss can be reduced, and fuel consumption and output can be improved. Can contribute to

FIGS. 4 and 5 show a second embodiment of the present invention.

In the second embodiment, the parts having the same functions as those in the first embodiment will be described with the same reference numerals.

A feature of the second embodiment is that a gear position detecting means (not shown) for detecting the engine speed detected by a crank angle sensor as the engine speed detecting means and a gear position of a transmission (not shown). ) Is provided with an oil temperature map including the vehicle speed detected in the step S).

That is, the control for estimating the engine oil temperature by the control means will be described. The starting conditions for the control for estimating the engine oil temperature are the same as those in the first embodiment.
This is a case where the following two items are satisfied respectively. (1) Complete explosion mode (2) Water temperature TWN ≧ predetermined water temperature KTWOILH (80 degrees)
[KTWOILHH (5 degrees)] KTWOILHH: Hysteresis component

The contents of the control in the control of the engine oil temperature by the control means will be described. As shown in FIG. 4, when the above-mentioned items (1) and (2) of the start-up conditions are respectively satisfied, TMTOIL The estimated oil temperature THOIL is calculated every # (1000 ms).

In other words, the target oil temperature THOIL is obtained by the expression THOIL = kthoinv · kthoild.

At this time, the oil temperature map value kthoinv
Is an oil temperature map MAPHOIL comprising an engine speed detected by a crank angle sensor as the engine speed detecting means and a vehicle speed detected by a gear position detecting means.
(HNDATA / GEAR).

Further, an intake pipe map TKOILL which changes the correction coefficient kthoild according to the value of the intake pipe pressure.
D (PMTP).

Then, a difference between two sampled latest and consecutive target oil temperatures is calculated, and the difference is multiplied by a correction coefficient kdeltoil determined according to the calculated difference to obtain a correction value. Is added to the target oil temperature to estimate the engine oil temperature.

That is, the estimated oil temperature THOIL is calculated by the equation THOIL = toilold + (THOIL-toi
(old) · kdeltoil toilold: previous value kdeltoil: correction coefficient

The setting of the correction coefficient kdeltoil is performed as follows. (1) In case of THOIL-toilold ≧ kdeltoil = KDELOILU # (0.05) (2) In case of TTHOLIL-toilold <kdeltoil = KDELOILD # (0.02)

The initial value of the estimated oil temperature THOIL is set to TOILH0 # (90 degrees).

Further, the estimated oil temperature THOIL is stored in a backup even after the ignition is turned off.

The condition for canceling the oil temperature estimation control is as follows: water temperature TWN <predetermined water temperature KTWOILL (70 degrees) [KT
WOILLH (5 degrees)]. KTWOILLH represents a hysteresis component.

When the condition for canceling the oil temperature estimation control is satisfied, the estimated oil temperature THOIL is set to THOIL = TOILH0 # (90 degrees).

Referring to the flowchart of FIG. 5, in the second embodiment, the oil comprising the engine speed detected by the crank angle sensor 78 and the vehicle speed detected by the vehicle speed sensor 88 in the first embodiment described above. Instead of the process (104) for obtaining the oil temperature map value from the temperature map MAPHOIL (HNDATA / VSP), as shown in FIG.
M), the oil temperature map M
A process (204) for obtaining an oil temperature map value from APTHOIL (HNDATA / GEAR) is performed.

In this case, the existing sensor used for controlling the engine or the transmission can be used without specially providing the engine oil temperature sensor, so that the system can be simplified and the cost can be reduced.

FIG. 6 shows a third embodiment of the present invention.

A feature of the third embodiment is that a difference between two sampled latest and consecutive target oil temperatures is calculated, and the difference is multiplied by a correction coefficient 2 determined in accordance with the calculated difference. A correction value is obtained by the calculation, and a value obtained by adding the obtained correction value to the target oil temperature is estimated as the engine oil temperature.

That is, instead of the processes (104) and (106) in the flowchart of FIG. 1 in the first embodiment of the present invention, as shown in FIG. 6, the engine speed detected by the crank angle sensor and the vehicle speed sensor are used. An oil temperature map value is obtained from an oil temperature map composed of the detected vehicle speed (or transmission gear position) (304), and the target oil temperature is calculated by the following equation: target oil temperature = oil temperature map value / correction coefficient 1 (intake pipe pressure) The target oil temperature is calculated by the following formula (305), and the target oil temperature is calculated by the following equation. Target oil temperature = Target oil temperature + Correction value Correction value: The difference between the two latest and consecutive sampled target oil temperatures and the correction coefficient 2 (According to the difference between the target oil temperatures) (306).

In this case, an existing sensor used for engine or transmission control can be used without specially providing an engine oil temperature sensor, which can contribute to simplification of the system and cost reduction. Since the target oil temperature was sampled twice and the target oil temperature was corrected using the value obtained from the difference, it was possible to estimate the engine oil temperature with higher accuracy, and the reliability in the estimation control of the engine oil temperature was improved. Can be improved.

The present invention is not limited to the above-described first to third embodiments, and various modifications can be made.

For example, in the first or second embodiment of the present invention, the oil temperature map composed of the engine speed and the vehicle speed (or the gear position of the transmission) is used. It is also possible to adopt a special configuration that takes into account information that changes according to the running conditions of the vehicle, such as the distance, running time, and catalyst temperature.

In this case, even if the engine oil temperature sensor is not specially provided, the use state of the existing sensor used for the engine or the transmission control is expanded, and the system can be simplified and the cost can be reduced. Can contribute.

In the first embodiment of the present invention,
When the estimated oil temperature is higher than a predetermined value which is the set oil temperature,
Although the idle speed is set high by the control means, a special configuration is adopted in which the elapsed time from the start of the engine is measured, and after the set time has elapsed, the idle speed is set high by the control means. It is also possible.

That is, the rise of the estimated oil temperature is estimated based on the elapsed time from the start of the engine.

In this case, an oil pump that is smaller than the conventional one and has a smaller discharge rate can be used satisfactorily. By using a small oil pump, mechanical loss can be reduced, and fuel efficiency and output can be improved. Can contribute to

[0079]

As described above in detail, according to the present invention, there is provided an engine oil temperature estimating method including an engine speed detecting means for detecting an engine speed and a vehicle speed detecting means for detecting a vehicle speed. The target oil temperature is a value obtained by multiplying an oil temperature map value obtained from the engine speed detected by the engine speed detecting means and the vehicle speed detected by the vehicle speed detecting means by a correction coefficient that changes according to the value of the intake pipe pressure. By estimating the engine oil temperature from this target oil temperature, it is possible to use the existing sensor used for engine or transmission control without specially installing an engine oil temperature sensor. It can contribute to simplification and cost reduction.

Further, in the engine oil temperature estimating method including the engine speed detecting means for detecting the engine speed and the gear position detecting means for detecting the gear position of the transmission, the engine speed detected by the engine speed detecting means is provided. A value obtained by multiplying an oil temperature map value obtained from the rotational speed and the vehicle speed detected by the gear position detecting means of the transmission by a correction coefficient that changes according to the value of the intake pipe pressure is set as a target oil temperature. By estimating the engine oil temperature from the oil temperature, existing sensors used for engine or transmission control can be used without specially installing an engine oil temperature sensor, thus simplifying the system and reducing costs. Can contribute to

[Brief description of the drawings]

FIG. 1 is a flowchart of engine oil temperature estimation control according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of an engine oil temperature estimation system.

FIG. 3 is a diagram showing control contents of an engine oil temperature estimation system.

FIG. 4 is a diagram showing control contents of an engine oil temperature estimation system according to a second embodiment of the present invention.

FIG. 5 is a flowchart showing only a main part of engine oil temperature estimation control according to a second embodiment of the present invention.

FIG. 6 is a flowchart showing only a main part of engine oil temperature estimation control according to a third embodiment of the present invention.

[Explanation of symbols]

2 Engine 22 Air cleaner 26 Throttle body 28 Surge tank 30 Intake manifold 32 Intake passage 34 Throttle valve 36 Exhaust manifold 38 Exhaust pipe 40 Catalytic converter 42 Exhaust passage 46 PCV valve 52 Fuel injection valve 56 Fuel tank 64 Evaporation passage 68 Canister 70 Purge passage 72 Bypass passage 74 Bypass air amount control valve (also called "ISC valve") 78 Crank angle sensor 80 Water temperature sensor 82 Throttle sensor 84 Pressure sensor 86 O2 sensor 88 Vehicle speed sensor 90 Knock sensor 92 Oil pressure sensor 94 Engine oil temperature estimation system 96 Control means

Claims (4)

[Claims] 1. An engine oil temperature estimating method comprising: engine speed detecting means for detecting an engine speed; and vehicle speed detecting means for detecting a vehicle speed. A value obtained by multiplying an oil temperature map value obtained from the vehicle speed detected by the vehicle speed detecting means by a correction coefficient that changes according to the value of the intake pipe pressure is set as a target oil temperature. A method for estimating an engine oil temperature, comprising estimating a temperature. 2. An engine oil temperature estimating method comprising an engine speed detecting means for detecting an engine speed and a gear position detecting means for detecting a gear position of a transmission, wherein the engine speed is detected by the engine speed detecting means. The oil temperature map value obtained from the engine speed and the vehicle speed detected by the gear position detecting means of the transmission,
An engine oil temperature estimating method, wherein a value obtained by multiplying a correction coefficient that changes in accordance with a value of an intake pipe pressure is set as a target oil temperature, and an engine oil temperature is estimated from the target oil temperature. 3. The most recent and consecutive 2 sampled
The difference between the two target oil temperatures is calculated, the difference is multiplied by a correction coefficient determined in accordance with the calculated difference to obtain a correction value, and a value obtained by adding the obtained correction value to the target oil temperature is estimated as the engine oil temperature. The method according to claim 1 or 2, wherein the engine oil temperature is estimated. 4. The idle speed is set high when the estimated oil temperature is higher than a set oil temperature.
The engine oil temperature estimation method according to any one of claims 1 to 3.