Patent Application
20140223987
This application claims the benefit of Japanese Patent Application No. 2013-025824, filed Feb. 13, 2013 which is hereby incorporated by reference herein in its entirety.
1. Field of the Invention
The present invention relates to an apparatus for detecting an imbalance abnormality in the cylinder air-fuel ratio of a multi-cylinder internal combustion engine, and more particularly, to an apparatus that detects a major imbalance of the air-fuel ratio among cylinders in a multi-cylinder internal combustion engine.
2. Description of the Related Art
In an internal combustion engine equipped with an exhaust purification system that utilizes a catalyst, pollutants in exhaust are efficiently purified by the catalyst, and thus control of the mixing proportion between air and fuel in the air-fuel mixture that is burned in the internal combustion engine, or control of the air-fuel ratio, is essential. In order to perform such control of the air-fuel ratio, an air-fuel ratio sensor is provided in the exhaust passage of the internal combustion engine, and a feedback control is carried out to match a detected air-fuel ratio to a target air-fuel ratio.
Meanwhile, in a multi-cylinder internal combustion engine, since ordinarily the same control amount for all cylinders is used to conduct the air-fuel ratio control, the actual air-fuel ratio may become imbalanced across cylinders, even if the air-fuel ratio control is executed. If the degree of the imbalance at this point is small, it would be absorbable by the air-fuel ratio feedback control, and pollutants in the exhaust may still be purified by the catalyst. Thus, the imbalance does not affect exhaust emissions, and does not pose a particular problem.
However, if the air-fuel ratio among cylinders is greatly imbalanced due to factors such as a failure of the fuel injection system in some of the cylinders for example, the imbalance causes worsened exhaust emissions, and poses a problem. It is desirable to detect such large air-fuel ratio imbalances that worsen exhaust emissions as an abnormality. Particularly in the case of an internal combustion engine for an automobile, in order to prevent vehicle travel with worsened exhaust emissions from occurring, there is demand for onboard detection of cylinder air-fuel ratio imbalance abnormality, and recently there has also been movement to legally enforce such a feature.
In order to detect cylinder air-fuel ratio imbalance abnormality, the device described in Japanese Patent Laid-Open No. 2012-092803, for example, uses the output of an air-fuel ratio sensor placed in a junction part of an exhaust pipe. The device is configured to compare the value of a parameter correlated with the degree of fluctuation in the output of the air-fuel ratio sensor against a predetermined abnormality threshold value, and determine that an imbalance abnormality has occurred in the case of exceeding the abnormality threshold value.
Meanwhile, in a multi-cylinder internal combustion engine, if the atmospheric pressure changes, the degree of exhaust interference also changes, and the output of an air-fuel ratio sensor becomes different. Consequently, determining abnormality by comparing against a fixed abnormality threshold value makes precision of determination inconsistent. For this reason, in order to eliminate the influences of atmospheric pressure and improve the detection precision, the device in the Japanese Patent Laid-Open No. 2012-092803 is configured to correct, on the basis of the atmospheric pressure, at least one of either the value of the parameter correlated with the degree of fluctuation in the output of the air-fuel ratio sensor, or the abnormality threshold value.
However, the degree of exhaust interference among cylinders also changes depending on the load. For this reason, determining abnormality without taking exhaust interference into account makes precision of determination inconsistent.
Accordingly, the present invention was devised in light of the above circumstances, and an object thereof is to provide an apparatus for detecting a cylinder air-fuel ratio imbalance abnormality of a multi-cylinder internal combustion engine that may further improve precision of detection and prevent misdetections.
One mode of the present invention is an apparatus for detecting cylinder air-fuel ratio imbalance abnormality of a multi-cylinder internal combustion engine, provided with: one or multiple air-fuel ratio sensors installed in an exhaust passage of the multi-cylinder internal combustion engine;
an abnormality detecting unit that detects a cylinder air-fuel ratio imbalance abnormality by comparing a value of a parameter correlated with a degree of fluctuation in the air-fuel ratio sensor output to an abnormality threshold value; and
a correcting unit that corrects at least one of the value of the parameter or the abnormality threshold value on the basis of atmospheric pressure;
wherein an amount of correction performed by the correcting unit is modified according to a load of the multi-cylinder internal combustion engine.
In a preferred mode, the correcting unit corrects the value of the parameter, while the amount of correction is modified in a direction such that an absolute value of the degree of fluctuation increases as the load increases.
In another preferred mode, the correcting unit corrects the value of the abnormality threshold value, while the amount of correction is modified in a direction such that an absolute value of the degree of fluctuation decreases as the load increases.
In another preferred mode, multiple, mutually differing correcting units are provided, and the mutually differing correcting units are applied to one part and another part of a plurality of cylinders.
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).
Hereinafter, exemplary embodiments of the present invention will be described on the basis of the attached drawings.
In addition, an injector (fuel injection valve) 2 is provided for each cylinder. In other words, the injectors 2 inject fuel into the intake passage of a corresponding cylinder, and particularly into an intake port (not illustrated). Also, each cylinder is provided with a spark plug 13 for igniting the air-fuel mixture inside the cylinder.
The intake passage 7 for introducing intake air into each cylinder includes, besides the above intake ports, a surge tank 8 that acts as a junction part, an intake manifold 9 that joins the intake port of each cylinder to the surge tank 8, and an intake pipe 10 on the upstream side of the surge tank 8. The intake pipe 10 is provided with an airflow meter 11 and an electronically controlled throttle valve 12 in an order from the upstream side. The airflow meter 11 outputs a signal whose magnitude corresponds to the intake flow rate.
A right exhaust passage 14R is provided for the right bank BR, while a left exhaust passage 14L is provided for the left bank BL. The right and left exhaust passages 14R and 14L converge on the upstream side of a downstream catalyst 19. Since the configuration of the exhaust systems upstream to this convergence position is the same for both banks, herein only the right bank BR side will be explained, whereas the left bank BL side is labeled with the same signs in the drawing, and omitted from explanation.
The right exhaust passage 14R includes an exhaust port (not illustrated) for each of the cylinders #2, #4, #6, and #8, an exhaust manifold 16 that collects exhaust gas from these exhaust ports, and an exhaust pipe 17 installed on the downstream side of the exhaust manifold 16. In addition, an upstream catalyst 18 is provided in the exhaust pipe 17. On the upstream and downstream sides of the catalyst 18 (immediately before and immediately after), there are respectively installed a pre-catalyst sensor 20 and a post-catalyst sensor 21, which are air-fuel ratio sensors for detecting the air-fuel ratio of exhaust gas. In this way, one each of a shared upstream catalyst 18, pre-catalyst sensor 20, and post-catalyst sensor 21 are respectively provided for multiple cylinders (or a cylinder group) belonging to one of the banks. Note that it is also possible to not converge the right and left exhaust passages 14R and 14L, and provide individual downstream catalysts 19. Two or more air-fuel ratio sensors may also be provided for each of the exhaust passages 14R and 14L. Alternatively, one or multiple air-fuel ratio sensors may be provided on the downstream side of the convergence point of both exhaust passages 14R and 14L.
The engine 1 is additionally provided with an electronic control unit (hereinafter referred to as ECU) 100 that acts as a control unit and a detection unit. The ECU 100 is a commonly known microprocessor, and includes components such as a CPU, ROM, RAM, input/output ports, and a storage device, while none of which are illustrated. Besides the above airflow meter 11, pre-catalyst sensor 20, and post-catalyst sensor 21, various other sensors, such as a crank position sensor 22 for detecting the crank angle or a position in the rotary direction of the engine 1, an accelerator position sensor 23 for detecting the accelerator position, a water temperature sensor 24 for detecting the temperature of engine cooling water, and an atmospheric pressure sensor 25 which is positioned inside the case housing the ECU 100 and which detects the atmospheric pressure, are electrically connected to the ECU 100 via an A/D converter or the like (not illustrated). The ECU 100, on the basis of operating input from the driver and detected values from various sensors, controls the injectors 2, the spark plugs 13, and the throttle valve 12 to obtain a desired output, thereby controlling the fuel injection rate, the fuel injection timing, the ignition timing, the throttle position, and the like.
The throttle valve 12 is provided with a throttle position sensor (not illustrated), and a signal from the throttle position sensor is sent to the ECU 100. The ECU 100 ordinarily performs a feedback control to set the position of the throttle valve 12 (the throttle position) to a position determined according to the accelerator position.
Also, the ECU 100, on the basis of a signal from the airflow meter 11, detects the amount of intake airflow per unit time, or in other words, the intake airflow rate. The ECU 100 then detects the load on the engine 1 on the basis of at least one of the detected accelerator position, the throttle position, and the intake airflow rate.
The ECU 100, on the basis of a crank pulse signal from the crank position sensor 22, detects the crank itself while also detecting the rotation rate of the engine 1. Herein, “rotation rate” refers to the number of revolutions per unit time, and is synonymous with the rotational speed. In the present embodiment, “rotation rate” refers to the number of revolutions per minute, i.e. “rpm”.
The pre-catalyst sensor 20 is made up of what is called a wide-range air-fuel ratio sensor, and is capable of continuously detecting the air-fuel ratio over a comparatively wide range.
On the other hand, the post-catalyst sensor 21 is what is called an O2 sensor, and has the characteristic of its output value varying sharply about the stoichiometric value.
The upstream catalyst 18 and the downstream catalyst 19 are both made up of a three-way catalyst, and when the air-fuel ratio A/F of respectively inflowing exhaust gas is near-stoichiometric, simultaneously purify the pollutants NOx, HC, and CO in the exhaust. The air-fuel ratio window in which these three pollutants may be efficiently purified is comparatively narrow.
Accordingly, during ordinary engine operation, the ECU 100 executes an air-fuel ratio feedback control (stoichiometric control) in order to keep the air-fuel ratio of exhaust gas flowing into the upstream catalyst 18 near-stoichiometric. This air-fuel ratio feedback control is made up of a primary air-fuel ratio control (primary air-fuel ratio feedback control) that performs feedback control of the air-fuel ratio of the air-fuel mixture (specifically, the fuel injection rate) so that the exhaust air-fuel ratio detected by the pre-catalyst sensor 20 becomes stoichiometric at a predetermined target air-fuel ratio, and an auxiliary air-fuel ratio control (auxiliary air-fuel ratio feedback control) that performs feedback control of the air-fuel ratio of the air-fuel mixture (specifically, the fuel injection rate) so that the exhaust air-fuel ratio detected by the post-catalyst sensor 21 becomes stoichiometric.
In this way, in the present embodiment, the reference value of the air-fuel ratio is stoichiometric, and the fuel injection rate corresponding to stoichiometric (referred to as a stoichiometric-equivalent value) is the reference value for the fuel injection rate. However, the reference values for the air-fuel ratio and the fuel injection rate may also be set to other values.
The air-fuel ratio feedback control is conducted on a per-bank basis (in other words, for each bank). For example, the detected values from the pre-catalyst sensor 20 and the post-catalyst sensor 21 on the left bank BL side are used only for the air-fuel ratio feedback control of the cylinders #1, #3, #5, and #7 belonging to the left bank BL, and are not used for the air-fuel ratio feedback control of the cylinders #2, #4, #6, and #8 belonging to the right bank BR. The reverse is similar. The air-fuel ratio feedback control is executed as though there were two independent, straight 4-cylinder engines. Also, in the air-fuel ratio feedback control, the same control amount is uniformly used for each cylinder belonging to the same bank.
In addition, to give an example of the ignition sequence for an engine 1 equipped with the above cylinder array and a right-hand 2-plane crankshaft, the cylinder sequence is #1, #8, #7, #3, #6, #5, #4, #2, and the ignition interval is an equal interval every 90 degrees CA when viewing the engine as a whole.
However, when the right bank BR and the left bank BL are each viewed individually, the ignition intervals are both unequal intervals, and the intervals respectively differ for the right bank BR and the left bank BL. Herein, provided that 0 degrees is the point at which the cylinder #1 on the left bank BL is ignited, subsequently the cylinder #8 on the right bank BR is ignited after 90 degrees CA, and next the cylinder #7 on the left bank BL is ignited after 90 degrees CA, and then the cylinder #3 on the same left bank BL is ignited after 90 degrees CA. In this way, although ignition of each cylinder occurs every 90 degrees CA, the interval is not equal in the right bank BR and the left bank BL internally.
Now assume that a failure of the injector 2 or the like occurs, for example in some of the cylinders (particularly in one cylinder), and an air-fuel ratio imbalance occurs among the cylinders. For example, on the left bank BL, in some cases insufficient valve closure of an injector 2 may cause the fuel injection rate of the cylinder #1 to increase past the fuel injection rate of the other cylinders #3, #5, and #7, causing the air-fuel ratio of the cylinder #1 to shift farther to the rich side than the air-fuel ratio of the other cylinders #3, #5, and #7.
Even at this point, if a comparatively large correction value is applied by the above air-fuel ratio feedback control, in some cases it is possible to keep the air-fuel ratio of the total gas (the converged exhaust gas) supplied to the pre-catalyst sensor 20 at the stoichiometric rate. However, when viewed per-cylinder, the cylinder #1 is much richer than stoichiometric, while the cylinders #3, #5, and #7 are leaner than stoichiometric. Only the overall balance is stoichiometric, which is clearly not preferable from an emissions standpoint. Consequently, in the present embodiment, an apparatus that detects such a cylinder air-fuel ratio imbalance abnormality is provided.
As illustrated in
In addition, as illustrated for cylinder #3 only in
As the above description demonstrates, if an air-fuel ratio imbalance abnormality occurs, the fluctuation in the output of the pre-catalyst sensor 20 increases. Thus, by monitoring the degree of fluctuation, it is possible to detect an air-fuel ratio imbalance abnormality. In the present embodiment, there is calculated a fluctuation parameter, which is a parameter that is correlated with the degree of fluctuation in the output of the pre-catalyst sensor 20. This fluctuation parameter is compared against a predetermined abnormality determination value to detect an imbalance abnormality.
The method of calculating the fluctuation parameter will now be described.
As illustrated in
ΔA/Fn=A/Fn−A/Fn−1 (1)
This difference ΔA/Fn expresses the fluctuation of the pre-catalyst sensor output in the simplest way. As the degree of fluctuation increases, the absolute value of the slope of the air-fuel ratio chart increases, because the absolute value of the difference ΔA/Fn increases. Accordingly, it is also possible to treat the value of the difference ΔA/Fn at one predetermined timing as the fluctuation parameter.
However, in order to increase precision in the present embodiment, the average value of multiple differences ΔA/Fn are treated as the fluctuation parameter. In the present embodiment, within one engine cycle, differences ΔA/Fn at respective timings are totaled, and the final total value is divided by the number of samples N to calculate the average value of the difference ΔA/Fn within one engine cycle. Furthermore, average values of the difference ΔA/Fn are totaled for M engine cycles (where M=100, for example), and the final total value is divided by the number of cycles M to calculate the average value ΔA/FAV of the difference ΔA/Fn within M engine cycles, which is treated as the fluctuation parameter.
As the degree of fluctuation in the pre-catalyst sensor output increases, the absolute value of the average value of average values ΔA/FAV within M engine cycles also increases. Thus, if the absolute value of that average value ΔA/FAV is equal to or greater than a predetermined abnormality determination value, it is determined that there is an imbalance abnormality, where if that average value ΔA/FAV is less than the abnormality determination value, it is determined that there is no imbalance abnormality, or in other words, that the system is normal.
Note that since the pre-catalyst sensor output A/F increases in some cases and decreases in some cases, the above difference ΔA/Fn or their average value ΔA/FAV may be calculated for just one of these cases, and treated as the fluctuation parameter. Particularly in the case where only one cylinder is shifted to rich, the output when the pre-catalyst sensor receives exhaust gas corresponding to that one cylinder rapidly changes to the rich side (in other words, drops sharply), and thus it is possible to use decreasing values only for detecting rich shift (rich imbalance determination). In this case, only the region in the lower-right of the graph in
Also, any value that is correlated with the degree of fluctuation in the pre-catalyst sensor output may be treated as the fluctuation parameter. For example, it is also possible to calculate the fluctuation parameter on the basis of the difference between the maximum value and the minimum value (otherwise called the peak to peak) of the pre-catalyst sensor output within one engine cycle. This is because such a difference also increases as the degree of fluctuation in the pre-catalyst sensor output increases.
However, as discussed earlier, in a low-pressure environment, the change in the air-fuel ratio in the case in which the air-fuel ratio of only a specific cylinder is rich or lean (
In the correction coefficient map in
Next,
First, in step S101, it is determined whether or not a predetermined prerequisite suitable for conducting abnormality detection has been satisfied. This prerequisite is satisfied when all of the following conditions have been satisfied.
Of these, (6) indicates that the routine is based on the rich imbalance determination discussed earlier (the method that uses only decreasing values to detect rich shifts). The routine is ended in the case where the prerequisite is not satisfied. On the other hand, in the case where the prerequisite is satisfied, in step S102, the output A/Fn of the pre-catalyst sensor 20 (air-fuel ratio sensor) at the current timing is acquired, and in step S103, the output difference ΔA/Fn at the current timing is calculated with the earlier Eq. 1.
Next, in step S104, the atmospheric pressure Pn and the load KLn at the current timing are acquired. The atmospheric pressure Pn is acquired on the basis of a signal from the atmospheric pressure sensor 25. The atmospheric pressure Pn may also be acquired by an estimation calculation based on the throttle position and the airflow rate passing through the airflow meter. The load KLn is acquired on the basis of a signal from the accelerator position sensor 23, for example. The load KLn may also be acquired on the basis of another signal, such as a signal from the airflow meter 11, for example.
Next, in step S105, a correction coefficient Cn corresponding to the acquired atmospheric pressure Pn and the load KLn is calculated from the pre-created correction coefficient map (see
Next, in step S106, the output difference ΔA/Fn is corrected by multiplying the output difference ΔA/Fn at the current timing by the correction coefficient Cn at the current timing, and the corrected value ΔA/Fcn is calculated and stored in a predetermined storage area of the ECU 100.
Next, in step S107, it is determined whether the above process has finished 100 cycles. In the case of a negative determination, the above process is repeatedly executed until 100 cycles finish.
In the case in which 100 cycles have finished, in step S108, the average value ΔA/FAV of the corrected values ΔA/Fcn calculated up to this point is calculated by dividing the total value of the corrected values ΔA/Fcn by the number of samples N and the number of engine cycles M, for example.
Then, in step S109, it is determined whether or not the absolute value of the average value ΔA/FAV of the corrected values ΔA/Fcn is greater than a predetermined abnormality threshold value α. In the case where the absolute value ΔA/FAV of the corrected values is less than the abnormality threshold value α, the routine proceeds to step S110, it is determined that there is no imbalance abnormality, or in other words that the system is normal, and the routine ends.
On the other hand, in the case where the absolute value ΔA/FAV of the corrected values is equal to or greater than the abnormality threshold value α, the routine proceeds to step S111, it is determined that there is an imbalance abnormality, or in other words that there is a abnormality, and the routine ends. Note that, at the same time as determining abnormality, or in the case in which abnormality determination is successively returned for two trips (in other words, two consecutive trips, in which one trip lasts from engine start to stop), it is preferable to activate a warning device such as a check lamp to inform the user of the fact of the abnormality, and in addition, store the abnormality information in predetermined diagnosis memory in a form capable of being called by a maintenance worker.
As thus explained, in the present embodiment, the value of an average value ΔA/FAV, which is used as a fluctuation parameter correlated with the degree of fluctuation in the output of an air-fuel ratio sensor 20, is compared to an abnormality threshold value α, and in order to detect a cylinder air-fuel ratio imbalance abnormality, the value of the output difference ΔA/Fn used as the fluctuation parameter is corrected on the basis of the atmospheric pressure Pn, while an amount of correction (a correction coefficient Cn) is modified according to the load KLn. In this way, since the amount of correction is modified according to the load, the detection precision is improved while taking into account the influences of the load, and misdetections may be suppressed.
Next, a second exemplary embodiment of the present invention will be described. In the above first embodiment, a shared correction coefficient map is used for all cylinders, but instead of such a configuration, in the second embodiment, multiple types of mutually differing correction coefficient maps are used, and mutually differing types of correction coefficient maps are used for one part and another part of the multiple cylinders.
Particularly, in the second embodiment, individual correction coefficient maps are used for the multiple cylinders. In other words, a correction coefficient map as illustrated by example in
A cylinder air-fuel ratio imbalance abnormality detection routine according to the second embodiment will now be described using
The determination of whether or not a predetermined prerequisite is satisfied in step S201, the acquisition of the output A/Fn of the pre-catalyst sensor 20 (air-fuel ratio sensor) in step S202, the calculation of the output difference ΔA/Fn in step S203, and the acquisition of the atmospheric pressure Pn and the load KLn in step S204 are respectively similar to steps S101 to S104 in the foregoing first embodiment.
In step S204A, the cylinder whose exhaust gas corresponds to the currently detected air-fuel ratio is determined. This determination is conducted on the basis of a signal from the crank position sensor 22, while taking into account a predetermined delay time (for example, by adding a correction according to a signal from the airflow meter 11).
Next, in step S205, a correction coefficient Cn corresponding to the acquired atmospheric pressure Pn and the load KLn is calculated from a correction coefficient map corresponding to that cylinder. In other words, from among the multiple correction coefficient maps created in advance for each of the cylinders #1 to #8 and stored in the ROM of the ECU 100, the one corresponding to the cylinder determined in step S204A is selected and used, and a correction coefficient Cn is calculated thereby.
The processing in steps S206 to S211 is similar to the processing in steps S106 to S111 in the foregoing first embodiment.
As a result of the above process, in the second embodiment, the output difference ΔA/Fn used as a fluctuation parameter is corrected on the basis of the atmospheric pressure Pn, while an amount of correction (a correction coefficient Cn) is modified according to the load KLn. In this way, since the amount of correction is modified according to the load, the detection precision is improved while taking into account the influences of the load, and misdetections may be suppressed.
Also, given that the influences on the degree of exhaust interference due to changes in the load differs for each cylinder, in the second embodiment, multiple, mutually differing correction coefficient maps are provided, and mutually differing correction coefficient maps are applied to one part and another part of the multiple cylinders in order to determine an amount of correction. Consequently, since the amount of correction is determined by a different correction coefficient for each cylinder, the detection precision is improved, and misdetections may be suppressed.
Note that although a different correction coefficient map is used for each of the cylinders #1 to #8 in the second embodiment, the number of types of correction coefficient maps is not required to be the same number as the number of cylinders, as long as there are a plurality of types. For example, it is possible to use a shared correction coefficient map for a plurality of cylinders having a mutually similar geometrical shape or layout of the exhaust passage up to the air-fuel ratio sensor. Also, in the case in which the geometrical shape or layout of the exhaust passage is symmetric or approximately symmetric between multiple banks or cylinder groups, for the multiple cylinders in a symmetric relationship (for example, cylinders #1 and #2, #3 and #4, #5 and #6, and #7 and #8 in a V8 engine like in the second embodiment), respectively shared (that is, a total of four types of) correction coefficient maps may be used.
The above thus describes preferred embodiments of the present invention in detail, but various other embodiments of the present invention are also conceivable. For example, in the foregoing embodiments, a rich shift abnormality is detected by using only the decreasing (changing to the rich side) air-fuel ratio sensor output. However, a configuration that uses only the increasing (changing to the lean side) air-fuel ratio sensor output, or a configuration that uses both the decreasing and the increasing air-fuel ratio sensor output, is also possible. Also, it is possible to detect not only rich shift abnormality but also lean shift abnormality, and air-fuel ratio imbalance abnormality may also be broadly detected without distinguishing between rich shifts and lean shifts.
Also, although the foregoing embodiments correct the value of the fluctuation parameter, the abnormality threshold value α may also be corrected according to the atmospheric pressure P and the load KL. In the case of correcting the abnormality threshold value α, it is suitable to modify a correction coefficient by which to multiply the abnormality threshold value α in a direction such that the absolute value of the degree of fluctuation decreases as the atmospheric pressure P increases, and as the load KL increases. Furthermore, both the fluctuation parameter and the abnormality threshold value may also be corrected on the basis of the atmospheric pressure P and the load KL.
Also, in the foregoing embodiments, the example of detecting a rich shift abnormality was primarily described in order to ease understanding. However, the present invention is also applicable to the case of detecting a lean shift abnormality. The present invention is not limited to a V8 engine, and is also applicable to a V-type engine with a different cylinder count (such as 6-cylinder, 10-cylinder, or 12-cylinder, for example), an internal combustion engine having a plurality of cylinder groups such as a horizontally opposed engine, or an inline engine.
An embodiment of the present invention is not limited to the foregoing embodiments and their modifications, and all such modifications and applications or their equivalents that are encompassed by the ideas of the present invention as stipulated by the claims are to be included in the present invention. Consequently, the present invention is not to be interpreted in a limited manner, and is also applicable to other arbitrary technologies belonging within the scope of the ideas of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-025824 | Feb 2013 | JP | national |
