Method and apparatus for calculating down time of engine of vehicle

Abstract

The method for determining the stop time of the vehicle engine comprises the following steps of: pre-calibrating a specific relationship between the stop time of the engine and a temperature value and a temperature attenuation value at a closing moment at a specific environment temperature; the method comprises the following steps of: pre-calibrating a correction coefficient of a relationship between engine shutdown time and a temperature value and a temperature attenuation value at a shutdown moment at different environment temperatures relative to a specific relationship, wherein the correction coefficient comprises the following steps of: obtaining a temperature value when an engine is shut down; acquiring a temperature value when the engine is restarted; calculating a temperature attenuation value based on the shutdown and restart time temperature values; basic downtime is calculated based on the shutdown moment temperature value, the temperature attenuation value and a specific relation; acquiring an environment temperature value during the shutdown period of the engine, and comparing the environment temperature value with each environment temperature value corresponding to the correction coefficient to acquire a corresponding basic correction coefficient; and calculating the final downtime based on the basic correction coefficient and the basic downtime. The invention also relates to an apparatus for determining the engine downtime and a non-transitory machine-readable storage medium.

Description

Technical Field

[0001] The present application relates to a method and device for calculating the downtime of a vehicle's engine, and particularly to a method and device for calculating the downtime of a diesel engine. Background Art

[0002] To meet the more stringent vehicle emission and On-Board Diagnostics (OBD) system regulatory requirements, more and more sensors are introduced into the ECU for emission control or OBD monitoring. If the output signals of these sensors are abnormal or unreasonable, it will inevitably have a negative impact on emission control and OBD monitoring, such as high emissions or incorrect diagnosis by the OBD system.

[0003] According to the current regulatory requirements, the ECU needs to have the ability to identify whether the output signal of the sensor is reasonable. For temperature sensors, the current common practice is to cross-compare between two or more temperature sensors. If a large difference is found between the signal of a certain sensor and the signals of other sensors, it is determined that the signal of this sensor is unreasonable, and the vehicle instrument panel will automatically activate the fault indicator light, requiring the driver to repair it as soon as possible.

[0004] When the engine is working, the temperature signals at different positions of the vehicle are very different. Moreover, the temperature signal itself has a hysteresis characteristic. These two factors greatly affect the accuracy of the cross-comparison judgment of the sensor signal. To reduce or eliminate these two influencing factors, we introduce the condition of the engine downtime. After the engine stops running, all temperature heat sources are cut off. As the continuous downtime extends, the values of all temperature points will infinitely approach the ambient temperature value. Then, the mutual comparison check between temperature sensors can be carried out, and the probability of misjudgment will be greatly reduced.

[0005] Therefore, in order to accurately diagnose the rationality of the temperature sensor, it is necessary to introduce the engine downtime.

[0006] The current common solution is: implant a timing chip inside the ECU and develop the corresponding ECU software module; require the vehicle wiring harness to set up a separate ECU power supply line to ensure that the ECU is still stably powered after the driver cuts off the vehicle power supply switch. This solution can meet the project requirements, but the negative problems brought are the additional vehicle wiring harness design and manufacturing costs and the vehicle battery energy consumption problems. And there is a possible OBD cheating risk, such as deliberately cutting off the separate power supply of the ECU artificially, resulting in the OBD system being unable to detect the rationality of the temperature sensor.

[0007] However, according to the national standards for hazardous chemical transportation vehicles, a physical switch for cutting off the total power is required for the vehicle. When the driver leaves the vehicle, the power supply of the vehicle battery and all electrical appliances is switched to ensure safety.

[0008] In view of the above problems, a new method for obtaining the engine shutdown time is needed to solve the above problems. Summary of the Invention

[0009] In view of the above problems, the present invention aims to provide a new method for obtaining the engine shutdown time. The engine shutdown time obtained by this method can be used as a basis for accurately diagnosing the rationality of the vehicle's temperature sensor.

[0010] According to one aspect of the present invention, there is provided a method for determining the shutdown time of an engine of a vehicle. The method includes pre-calibrating a specific relationship between the shutdown time of the engine of the vehicle, the temperature value at the moment of engine shutdown, and the temperature decay value of the engine at a specific ambient temperature, and pre-calibrating a correction coefficient of the relationship between the shutdown time of the engine of the vehicle, the temperature value at the moment of engine shutdown, and the temperature decay value of the engine at a plurality of different ambient temperatures relative to the specific relationship. The method at least includes the following steps: when the engine is turned off, obtaining the temperature value at the moment of engine shutdown; when the engine is restarted, obtaining the temperature value at the moment of engine restart; calculating the temperature decay value of the engine based on the temperature value at the moment of engine shutdown and the temperature value at the moment of engine restart; calculating the basic shutdown time of the engine based on the temperature value at the moment of engine shutdown, the temperature decay value, and the specific relationship; obtaining the ambient temperature value during the shutdown of the engine of the vehicle as the basic ambient temperature value; comparing the basic ambient temperature value with each ambient temperature value corresponding to the correction coefficient to determine the basic correction coefficient corresponding to the basic ambient temperature value; and calculating the final shutdown time of the engine based on the basic correction coefficient and the basic shutdown time.

[0011] According to another aspect of the present invention, there is provided a device for determining the shutdown time of an engine of a vehicle, including:

[0012] A storage module configured to pre-store a specific relationship between the engine shutdown time of the vehicle, the temperature value at the engine shutdown moment, and the temperature decay value of the engine, and correction coefficients of the relationships between the engine shutdown time of the vehicle, the temperature value at the engine shutdown moment, and the temperature decay value of the engine at multiple different ambient temperatures relative to the specific relationship; a first acquisition module configured to acquire the temperature value at the engine shutdown moment when the engine shuts down and acquire the temperature value at the engine restart moment when the engine restarts; a first calculation module configured to calculate the temperature decay value of the engine based on the temperature value at the engine shutdown moment and the temperature value at the engine restart moment; a second calculation module configured to calculate the basic shutdown time of the engine based on the temperature value at the engine shutdown moment, the temperature decay value, and the specific relationship; a second acquisition module configured to acquire the ambient temperature value during the engine shutdown of the vehicle as the basic ambient temperature value; a third calculation module configured to determine a basic correction coefficient corresponding to the basic ambient temperature value by comparing the basic ambient temperature value with the ambient temperature value corresponding to the correction coefficient; a fourth calculation module configured to calculate the final shutdown time of the engine based on the basic correction coefficient and the basic shutdown time.

[0013] According to another aspect of the present invention, there is provided a non-transitory machine-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the method according to the present invention.

[0014] The method according to the present invention can obtain a relatively reliable engine shutdown time at low cost, thereby being able to diagnose the rationality of the temperature sensor of the vehicle relatively accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Hereinafter, embodiments herein will be described in more detail with reference to the drawings, wherein:

[0016] Figure 1 Exemplarily shown is a schematic diagram of an engine temperature signal, an engine speed signal, and an engine switch signal from before engine shutdown to after restart according to an embodiment of the present invention.

[0017] Figure 2 Exemplarily shown is a block diagram of a method according to an embodiment of the present invention.

[0018] Figure 3 Exemplarily shown is a flowchart of a method for calculating an engine shutdown time according to an embodiment of the present invention.

[0019] According to the detailed description carried out below in conjunction with the accompanying drawings, other purposes and features of the embodiments of this invention will become apparent. However, it should be understood that the accompanying drawings are designed only for illustrative purposes and are not intended to limit the scope of the present invention. DETAILED DESCRIPTION

[0020] Figure 1 The diagram exemplarily shows an engine temperature signal, an engine speed signal and an engine switch signal before the engine is shut down and after the engine is restarted according to one embodiment of the present invention.

[0021] exist Figure 1 In FIG. 1 , CUV1 represents a temperature signal curve of a vehicle engine. The temperature of the engine is obtained, for example, by a temperature sensor for measuring the temperature of the engine coolant. CUV2 represents an engine speed signal. CUV3 represents a signal diagram of an engine key switch, where the signal is 1 when the engine is started and the signal is 0 when the engine is turned off.

[0022] Depend on Figure 1 It can be seen that at time point A, the engine key switch is turned off, the engine stops working, and its signal (CUV2) becomes zero. From time point A, there is no heat input to the engine, and the engine temperature signal begins to decay from 80°C.

[0023] At time point B, the engine key switch is turned on and the engine starts to work again. At this time, the engine temperature signal has dropped to 30°C. From time point B, the engine temperature signal starts to rise.

[0024] The attenuation relationship of the engine temperature signal is related to the engine specifications and ambient temperature. For a specific engine, at a specific ambient temperature, the temperature attenuation value of the engine is a function of the temperature value at the time when the engine is shut down and the engine downtime. In other words, the engine downtime is a function of the temperature value at the time when the engine is shut down and the temperature attenuation value of the engine, as expressed by the following formula (1).

[0025] T= f(W, Δ) (1)

[0026] Wherein, T represents the downtime of the engine; W represents the temperature value at the time when the engine is shut down; Δ represents the difference between the temperature value at the time when the engine is shut down and the temperature value at the time when the engine is restarted, that is, the temperature attenuation value.

[0027] The scheme for calculating the engine downtime of the present invention is described in detail below.

[0028] a) Pre-calibrate the specific relationship between the engine shutdown time of the vehicle and the engine shutdown moment temperature value at the time of engine shutdown and the engine temperature decay value at a specific ambient temperature. The specific ambient temperature can be arbitrarily selected according to the region where the vehicle will be used and can be any value, for example, from -30°C to +30°C. The desired calibration results can be made into a table. An exemplary table is shown in Table 1.

[0029] Table 1 Engine Shutdown Time Calibration Table

[0030] <![CDATA[W 1 > <![CDATA[W 2 > <![CDATA[W 3 > …… <![CDATA[W n > <![CDATA[Δ 1 > <![CDATA[T 11 > <![CDATA[T 12 > <![CDATA[T 13 > …… <![CDATA[T 1n > <![CDATA[Δ 2 > <![CDATA[T 21 > <![CDATA[T 22 > <![CDATA[T 23 > …… <![CDATA[T 2n > …… <![CDATA[Δ m > <![CDATA[T m1 > <![CDATA[T m2 > <![CDATA[T m3 > …… <![CDATA[T mn >

[0031] Where, T 11 represents the basic engine shutdown time when the engine shutdown moment temperature value is W 1 and the difference between the engine shutdown moment temperature value and the start moment temperature value at restart is Δ 1 . And so on, T mn represents the basic engine shutdown time when the engine shutdown moment temperature value is W n and the difference between the engine shutdown moment temperature value and the start moment temperature value at restart is Δ m .

[0032] The calibration process is preferably carried out during the R & D stage of the vehicle, or preferably before the vehicle leaves the factory. Of course, it is also possible to calibrate the basic engine shutdown time after the vehicle is manufactured. After calibration, the specific relationship is preferably stored in the reprogrammable read-only memory (RPROM) of the vehicle control unit (ECU).

[0033] b) Since at different ambient temperatures, the temperature decay rate of the engine after shutdown will vary. Therefore, according to the present invention, when calculating the engine shutdown time at other ambient temperatures different from the specific ambient temperature, a coefficient needs to be multiplied on this basic shutdown time.

[0034] Therefore, after pre-calibrating the specific relationship between the engine shutdown time of the vehicle and the engine shutdown moment temperature value at the time of engine shutdown and the engine temperature decay value at a specific ambient temperature, calibrate the corresponding correction coefficients of the relationship between the engine shutdown time of the vehicle and the engine shutdown moment temperature value at the time of engine shutdown and the engine temperature decay value at multiple different ambient temperatures relative to the specific relationship.

[0035] For example, assume that the specific ambient temperature for calibrating the specific relationship between the engine shutdown time, the temperature value at the engine shutdown moment when the engine is turned off, and the temperature decay value of the engine mentioned in a) is 25 °C. Then, when the ambient temperature is 25 °C, the correction factor is 1. When the ambient temperature is 0 °C, the correction factor is a value less than 1, such as 0.5. That is to say, if the temperature value at the engine shutdown moment is 80 °C and it takes 6 hours for the engine temperature value to drop to 25 °C when the ambient temperature is 25 °C, then when the ambient temperature is 0 °C, it takes 3 hours for the engine temperature value to drop to 25 °C.

[0036] The above is only an example, and the correction factor is related to the specifications and models of the engine. The calibration process is preferably carried out during the vehicle R & D stage, or preferably before the vehicle leaves the factory. Of course, it is also possible to calibrate the basic shutdown time of the engine after the vehicle is manufactured. After calibration, the correction factor is preferably stored in the reprogrammable read-only memory (RPROM) of the vehicle control unit (ECU).

[0037] Figure 2 A block diagram of a method according to an embodiment of the present invention is exemplarily shown.

[0038] In Figure 2 M a1 represents a first acquisition module configured to acquire the temperature value W at the shutdown moment of the engine when the engine is turned off s and the temperature value W at the restart moment of the engine when the engine is restarted. a .

[0039] M c1 represents a first calculation module configured to calculate, using the temperature value W at the engine shutdown moment s and the temperature value W at the engine restart moment, a the difference Δ s between W a and W sa , that is, the temperature decay value.

[0040] M C2 represents a second calculation module configured to calculate the basic shutdown time T s using W sa and Δ. s .

[0041] M a2 represents a second acquisition module configured to acquire the ambient temperature value during the engine shutdown as the basic ambient temperature value W ePreferably, the base ambient temperature value is obtained in the following manner: when the engine is turned off, the ambient temperature value at the moment of engine shutdown is acquired, and when the engine is started, the ambient temperature value at the moment of engine startup is obtained. The median value of the ambient temperature value at the moment of engine shutdown and the ambient temperature value at the moment of engine restart is used as the base ambient temperature value. Optionally, in regions and seasons where the temperature change is small, the ambient temperature value at the moment of engine shutdown or the ambient temperature value at the moment of engine restart can also be used as the base ambient temperature value.

[0042] M C3 represents the third calculation module, which is configured to determine the base correction coefficient α corresponding to the base ambient temperature value by comparing the base ambient temperature value with each ambient temperature value stored in the storage module corresponding to different correction coefficients. For example, the correction coefficient corresponding to the ambient temperature closest to the base ambient temperature in the storage module can be selected as the base correction coefficient. Optionally, the base correction coefficient α is determined by interpolation.

[0043] M C4 represents the fourth calculation module, which is configured to calculate the final shutdown time T of the engine based on the base correction coefficient α and the base shutdown time e .

[0044] The following will combine the attached Figure 3 to describe in detail the method steps according to an embodiment of the present invention. Figure 3 Exemplarily, a flowchart of a method for calculating the engine shutdown time according to an embodiment of the present invention is shown.

[0045] In step S100, the ambient temperature value at the moment of engine shutdown and the temperature value at the moment of engine shutdown are acquired;

[0046] In step S110, the ambient temperature value at the moment of engine restart and the temperature value at the moment of engine restart are acquired;

[0047] In step S120, the temperature decay value Δ of the engine is calculated based on the temperature value at the moment of engine shutdown and the temperature value at the moment of engine restart; sa ;

[0048] In step S130, based on the temperature value at the moment of shutdown and the temperature decay value Δ sa and the specific relationship stored in the RPROM, the base shutdown time T of the engine is calculated; s ;

[0049] In step S140, the ambient temperature value during engine shutdown is acquired as the base ambient temperature value W; ePreferably, the intermediate value of the ambient temperature value at the engine shutdown moment and the ambient temperature value at the engine startup moment is used as the base ambient temperature value. Optionally, in regions and seasons with little temperature change, the ambient temperature value at the engine shutdown moment or the ambient temperature value at the engine restart moment can also be used as the base ambient temperature value.

[0050] In step S150, based on the base ambient temperature value and the correction coefficient stored in the RPROM, a base correction coefficient α corresponding to the base ambient temperature value is determined. Preferably, the base correction coefficient α is determined by interpolation;

[0051] In step S160, based on the base correction coefficient α and the base shutdown time T s the final shutdown time T of the engine is calculated e .

[0052] The present invention also provides a non-transitory machine-readable storage medium having instructions stored thereon that can be run by a computer system to perform the steps of the method according to the present invention described above. The non-transitory machine-readable storage medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a material composition affecting a machine-readable propagation signal, or a combination of one or more of them.

[0053] Therefore, although the features of the embodiments herein have been described, it can be understood that those skilled in the art can make various omissions, substitutions, and changes to the form and details of the shown method and its operations, and the step order of the above method is only exemplary, and it is possible to adjust the steps of the method of the present invention on the premise of being able to achieve the functions of the present invention. For example, all combinations of method steps that perform substantially the same function in substantially the same manner to achieve the same result are equivalent.

Claims

1. A method for determining the engine shutdown time of a vehicle, the method comprising pre-calibrating a specific relationship between the engine shutdown time of the vehicle, the temperature value at the engine shutdown moment, and the engine temperature decay value at a specific ambient temperature, and pre-calibrating a correction coefficient for the relationship between the engine shutdown time of the vehicle, the temperature value at the engine shutdown moment, and the engine temperature decay value at a plurality of different ambient temperatures relative to the specific relationship, the method at least comprising the following steps: When the engine is turned off, obtain the temperature value at the moment of engine shutdown (W s ); When restarting the engine, obtain the restart moment temperature value (W) of the engine a ) Based on the shutdown moment temperature value (W s ) and the restart moment temperature value (W a ), calculate the temperature decay value of the engine; Based on the temperature value at the shutdown moment, the temperature decay value, and the specific relationship, calculate the basic shutdown time (T s ) of the engine; Obtain the ambient temperature value during the engine shutdown of the vehicle as the basic ambient temperature value (W e ); Compare the base ambient temperature value (W e ) with each ambient temperature value corresponding to the correction factor to determine the base correction factor (α) corresponding to the base ambient temperature value; Based on the said basic correction coefficient (α) and the said basic downtime (T s ), the final downtime (T e ) of the engine is calculated.

2. The method according to claim 1, wherein, By multiplying the base downtime (T s ) by the base correction factor (α), the final downtime (T e ) is obtained.

3. The method according to claim 1 or 2, wherein, The basic ambient temperature value is obtained in the following manner, namely: when the engine is turned off, the ambient temperature value at the moment of engine shutdown is obtained as the basic ambient temperature value (W e ); or when the engine is restarted, the ambient temperature value at the moment of engine restart is obtained as the basic ambient temperature value (W e ); when the engine is turned off, the ambient temperature value at the moment of engine shutdown is obtained, and when the engine is restarted, the ambient temperature value at the moment of engine restart is obtained, and the intermediate value between the ambient temperature value at the moment of engine shutdown and the ambient temperature value at the moment of engine restart is used as the basic ambient temperature value.

4. The method according to claim 1 or 2, wherein, the temperature value at the engine shutdown moment and the temperature value at the engine startup moment are obtained by a temperature sensor for measuring the engine coolant.

5. The method according to claim 1, wherein, the specific relationship and the correction coefficient are stored in a storage module of a vehicle control unit (ECU).

6. The method according to claim 1, wherein, the engine is a diesel engine.

7. An apparatus for determining the engine shutdown time of a vehicle, comprising: a storage module configured to pre-store a specific relationship between the engine shutdown time of the vehicle, the temperature value at the engine shutdown moment, and the engine temperature decay value, and a correction coefficient for the relationship between the engine shutdown time of the vehicle, the temperature value at the engine shutdown moment, and the engine temperature decay value at a plurality of different ambient temperatures relative to the specific relationship; A first acquisition module configured to acquire a shutdown moment temperature value of the engine when the engine is shut down (W s ), and acquire a restart moment temperature value of the engine when the engine is restarted (W a ); A first calculation module configured to calculate a temperature decay value of the engine based on the shutdown moment temperature value (W s ) and the restart moment temperature value (W a ) of the engine; The second calculation module calculates the basic engine shutdown time (T s ) based on the shutdown moment temperature value, the temperature decay value, and the specific relationship; A second acquisition module configured to acquire an ambient temperature value during the shutdown of the engine of the vehicle as a basic ambient temperature value (W e ); A third calculation module configured to determine a basic correction coefficient (α) corresponding to the basic ambient temperature value (W e ) by comparing the basic ambient temperature value (W e ) with the ambient temperature value corresponding to the correction coefficient; The fourth calculation module is configured to calculate the final shutdown time (T s ) of the engine based on the basic correction coefficient (α) and the basic shutdown time (T e ).

8. The apparatus according to claim 7, wherein, By multiplying the base downtime (T s ) by the base correction factor (α), the final downtime (T e ) is obtained.

9. The apparatus according to claim 7 or 8, wherein, The basic ambient temperature value is obtained in the following manner, i.e., when the engine is turned off, the ambient temperature value at the moment of engine shutdown is obtained as the basic ambient temperature value (W e ); or when the engine is restarted, the ambient temperature value at the moment of engine restart is obtained as the basic ambient temperature value (W e ); when the engine is turned off, the ambient temperature value at the moment of engine shutdown is obtained, and when the engine is restarted, the ambient temperature value at the moment of engine restart is obtained, and the intermediate value between the ambient temperature value at the moment of engine shutdown and the ambient temperature value at the moment of engine restart is used as the basic ambient temperature value.

10. A non-transitory machine-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the method according to any one of claims 1-6 of the present invention.

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